1.1: Parable of the Surveyors
Our imagination is stretched to the utmost, not, as in fiction, to imagine things which are not really there, but just to comprehend those things which are there.
Richard P. Feynman
Disagree on northward and eastward separations and agree on distance
Daytime surveyor uses magnetic north
Once upon a time there was a Daytime surveyor 1 who measured off the king's lands. He took his directions of north and east from a magnetic compass needle. Eastward separations from the center of the town square he measured in meters. The northward direction was sacred. He measured northward separations from the town square in a different unit, in miles. His records were complete and accurate and were often consulted by other Daytimers.
Nighttime surveyor uses North-Star north
A second group, the Nighttimers 2 , used the services of another surveyor. Her north and east directions were based on a different standard of north: the direction of the North Star. She too measured separations eastward from the center of the town square in meters and sacred separations northward in miles. The records of the Nighttime surveyor were complete and accurate. Marked by a steel stake, every corner of a plot appeared in her book, along with its eastward and northward separations from the town square.
Daytimers and Nighttimers did not mix but lived mostly in peace with one another. However, the two groups often disputed the location of property boundaries. Why? Because a given corner of the typical plot of land showed up with different numbers in the two record books for its eastward separation from the town center, measured in meters (Figure \(\PageIndex{1}\)). Northward measurements in miles also did not agree between the two record books. The differences were small, but the most careful surveying did not succeed in eliminating them. No one knew what to do about this single source of friction between Daytimers and Nighttimers.
One fall a student of surveying turned up with novel open-mindedness. Unlike all previous students at the rival schools, he attended both. At Day School he learned from one expert his method of recording locations of gates of the town and corners of plots of land based on magnetic north. At Night School he learned the other method, based on North-Star north.
As days and nights passed, the student puzzled more and more in an attempt to find some harmonious relationship between rival ways of recording location. His attention was attracted to a particular plot of land, the subject of dispute between Daytimers and Nighttimers, and to the steel stakes driven into the ground to mark corners of this disputed plot. He carefully compared records of the two surveyors (Figure \(\PageIndex{1}\), Table \(\PageIndex{1}\)).
Student converts miles to meters
In defiance of tradition, the student took the daring and heretical step of converting northward measurements, previously expressed always in miles, into meters by multiplying with a constant conversion factor \(k\) 3 . He found the value of this conversion factor to be \(k=1609.344\) meters/mile. So, for example, a northward separation of \(3\) miles could be converted to \(k \times 3\) miles \(=1609.344\) meters \(/\) mile \(\times 3\) miles \(=4828.032\) meters. "At last we are treating both directions the same!" he exclaimed.
| Daytime surveyor's axes oriented to magnetic north | Nighttime surveyor's axes oriented to North-Star north | |||
|---|---|---|---|---|
|
Eastward
(meters) |
Northward
(miles) |
Eastward
(meters) |
Northward
(miles) |
|
| Town square | 0 | 0 | 0 | 0 |
| Stake A | 4010.1 | 1.8330 | 3950.0 | 1.8827 |
| Stake B | 5010.0 | 1.8268 | 4950.0 | 1.8890 |
| Stake C | 4000.0 | 1.2117 | 3960.0 | 1.2614 |
| Stake D | 5000.0 | 1.2054 | 4960.0 | 1.2676 |
Next the student compared Daytime and Nighttime measurements by trying various combinations of eastward and northward separation between a given stake and the center of the town square. Somewhere the student heard of the Pythagorean Theorem, that the sum of squares of the lengths of two perpendicular legs of a right triangle equals the square of the length of the hypotenuse. Applying this theorem, he discovered that the expression
\[\begin{array}{ccc}
& \textbf{Daytime} & \textbf{Daytime} \\
& \left[k \times\left(\begin{array}{c}
\text { northward } \\
\text { separation } \\
\text { (miles) }
\end{array}\right)\right]^{2} & +
~
\left[\begin{array}{c}
\text { eastward } \\
\text { separation } \\
\text { (meters) }
\end{array}\right]^{2}
\end{array} \nonumber\]
based on Daytime measurements of the position of steel stake \(C\) had exactly the same numerical value as the quantity
\[\begin{array}{ccc}
& \textbf{Nighttime} & \textbf{Nighttime} \\
& \left[k \times\left(\begin{array}{c}
\text { northward } \\
\text { separation } \\
\text { (miles) }
\end{array}\right)\right]^{2} & +
~
\left[\begin{array}{c}
\text { eastward } \\
\text { separation } \\
\text { (meters) }
\end{array}\right]^{2}
\end{array} \nonumber \]
computed from the readings of the Nighttime surveyor for stake \(C\) (Table \(\PageIndex{2}\)). He tried the same comparison on recorded positions of stakes \(A, B\) , and \(D\) and found agreement here too. The student's excitement grew as he checked his scheme of comparison for all stakes at the corners of disputed plots — and found everywhere agreement.
| Daytime measurements | Nighttime measurements | |
|---|---|---|
| Northward separation | 1.2117 miles | 1.2614 miles |
| Multiply by | k = 1609.344 meters/mile | k = 1609.344 meters/mile |
| to convert to meters: | 1950.0 meters | 2030.0 meters |
| Square the value | 3,802,500 (meters) 2 | 4,120,900 (meters) 2 |
| Eastward separation | 4000.0 meters | 3960.0 meters |
| Square the value and add | \(\underline{+16,000,000 \text { (meters)}^{2}}\) | \(\underline{+15,681,600 \text { (meters)}^{2}}\) |
| Sum of squares | \(=19,802,500 \text { (meters)}^{2}\) | \(=19,802,500 \text { (meters)}^{2}\) |
| Expressed as a number squared | = (4450 meters) 2 | = (4450 meters) 2 |
| This is the square of what measurement? | 4450 meters | 4450 meters |
Note that both daytime and nighttime measurements are the same.
Flushed with success, the student methodically converted all northward measurements to units of meters. Then the student realized that the quantity he had calculated, the numerical value of the above expressions, was not only the same for Daytime and and Nighttime measurements 4 . It was also the square of a length: (meters) 2 . He decided to give this length a name. He called it the distance from the center of town.
\[(\text { distance })^{2}=\left[\begin{array}{c} \text { northward } \\ \text { separation } \\ \text { (meters) } \end{array}\right]^{2}+\left[\begin{array}{c} \text { eastward } \\ \text { separation } \\ \text { (meters) } \end{array}\right]^{2} \nonumber\]
He said he had discovered the principle of invariance of distance ; he reckoned exactly the same value for distance from Daytime measurements as from Nighttime measurements, despite the fact that the two sets of surveyors' numbers differed significantly (Figure \(\PageIndex{2}\)).
After some initial confusion and resistance, Daytimers and Nighttimers welcomed the student's new idea. The invariance of distance, along with further results, made it possible to harmonize Daytime and Nighttime surveys, so everyone could agree on the location of each plot of land. In this way the last source of friction between Daytimers and Nighttimers was removed.
1 Daytime surveyor uses magnetic north
2 Nighttime surveyor uses North-Star north
3 Student converts miles to meters
4 Discovery: Invariance of distance


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bomb calorimeter
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device designed to measure the energy change for processes occurring under conditions of constant volume; commonly used for reactions involving solid and gaseous reactants or products
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calorie (cal)
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unit of heat or other energy; the amount of energy required to raise 1 gram of water by 1 degree Celsius; 1 cal is defined as 4.184 J
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calorimeter
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device used to measure the amount of heat absorbed or released in a chemical or physical process
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calorimetry
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process of measuring the amount of heat involved in a chemical or physical process
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chemical thermodynamics
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area of science that deals with the relationships between heat, work, and all forms of energy associated with chemical and physical processes
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endothermic process
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chemical reaction or physical change that absorbs heat
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energy
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capacity to supply heat or do work
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enthalpy (
H
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sum of a system’s internal energy and the mathematical product of its pressure and volume
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enthalpy change (Δ
H
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heat released or absorbed by a system under constant pressure during a chemical or physical process
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exothermic process
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chemical reaction or physical change that releases heat
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expansion work (pressure-volume work)
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work done as a system expands or contracts against external pressure
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first law of thermodynamics
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internal energy of a system changes due to heat flow in or out of the system or work done on or by the system
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heat (
q
)
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transfer of thermal energy between two bodies
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heat capacity (
C
)
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extensive property of a body of matter that represents the quantity of heat required to increase its temperature by 1 degree Celsius (or 1 kelvin)
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Hess’s law
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if a process can be represented as the sum of several steps, the enthalpy change of the process equals the sum of the enthalpy changes of the steps
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hydrocarbon
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compound composed only of hydrogen and carbon; the major component of fossil fuels
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internal energy (
U
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total of all possible kinds of energy present in a substance or substances
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joule (J)
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SI unit of energy; 1 joule is the kinetic energy of an object with a mass of 2 kilograms moving with a velocity of 1 meter per second, 1 J = 1 kg m
2
/s and 4.184 J = 1 cal
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kinetic energy
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energy of a moving body, in joules, equal to (where
m
= mass and
v
= velocity)
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nutritional calorie (Calorie)
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unit used for quantifying energy provided by digestion of foods, defined as 1000 cal or 1 kcal
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potential energy
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energy of a particle or system of particles derived from relative position, composition, or condition
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specific heat capacity (
c
)
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intensive property of a substance that represents the quantity of heat required to raise the temperature of 1 gram of the substance by 1 degree Celsius (or 1 kelvin)
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standard enthalpy of combustion
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heat released when one mole of a compound undergoes complete combustion under standard conditions
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standard enthalpy of formation
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enthalpy change of a chemical reaction in which 1 mole of a pure substance is formed from its elements in their most stable states under standard state conditions
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standard state
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set of physical conditions as accepted as common reference conditions for reporting thermodynamic properties; 1 bar of pressure, and solutions at 1 molar concentrations, usually at a temperature of 298.15 K
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state function
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property depending only on the state of a system, and not the path taken to reach that state
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surroundings
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all matter other than the system being studied
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system
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portion of matter undergoing a chemical or physical change being studied
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temperature
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intensive property of matter that is a quantitative measure of “hotness” and “coldness”
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thermal energy
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kinetic energy associated with the random motion of atoms and molecules
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thermochemistry
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study of measuring the amount of heat absorbed or released during a chemical reaction or a physical change
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work (
w
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energy transfer due to changes in external, macroscopic variables such as pressure and volume; or causing matter to move against an opposing force
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14.3: Precariousness as a Function of Policy and Industry Cultures
-
- Last updated
- Save as PDF
- John Banks & Stuart Cunningham
- University of California Press
In the overwhelmingly nonunionized games industry, advocacy for the sector is largely conducted by professional associations, and support is offered through state policies and programs. 29 This section considers the extent to which precariousness is a product of policy, advocacy, and industry self-governance.
A key feature of the games industry is that it is poorly understood by the political class. This is despite its size and growth rates globally dwarfing anything remotely comparable, and is an outstanding example of creative content and use driving technological innovation and take up, not the other way round, as is usually constructed in innovation policy and business strategy. It tends to fall between the three “stools” of cultural policy, industry and innovation policy, while its main interface with the political class and the wider populace is around social and educational policy concerns (violence, game-playing addiction, claims and counterclaims about educational benefits). Inconsistent or nonexistent policy support, particularly compared to other cultural industries, such as film and television, contributes to precariousness. Such policy inconsistency across different countries, as well as policy entrepreneurship or arbitrage between countries in bidding for the services of this high-skill component of the “creative class,” contributes to the hypermobility of games creatives.
In Australia, federal policy and programs supporting the industry had been piecemeal, 30 seeking to fit games into the established cultural template developed over decades for the arts, film, and television. They required developers to articulate game proposals as forms of storytelling to measure the cultural significance of the game. The long march toward a realistic balance between cultural and industry policy for the creative sector was accelerated by the industry transformations of the last five to seven years. Government accepted that very little original IP was being created; that Australian developers were locked into a fee-for-service system; that the country was no longer attractive to licensed IP; and that oversees competitive incentives were “luring” talent away from the country. A significant A$20 million package was developed, the Australian Interactive Games Fund, whose objectives were to promote industry growth and sustainability, support the development of new intellectual property, encourage skills retention and renewal, and maximize the creative opportunities of fast broadband. 31 With a change of government, however, the initiative was cancelled with only half the money spent.
At a state or provincial level, the policy rationale for support has been equally uneven, with an equal or perhaps even greater impact on precariousness for the labor force. The state of Victoria has been most consistent in its approach to games, which are recognized as a core component of the state’s industrial and employment base in its information and communication technology sector. Effective advocacy for the sector forestalled a cost-cutting attempt to close down support in 2012. Funding and programs in support of the sector are administered through a mainstream screen agency. The approach in Queensland was exclusively industrial and remained positive while the industry was generating jobs as midsize small businesses proliferated in the pre-GFC period. The collapse of several of the larger companies effectively eliminated games from a standard industry development policy logic as pursued within a department of state development and saw the policy focus narrow to a minor part of the screen agency’s remit. Government did little to arrest the collapse of the industry in the state, and has done little since. New South Wales, the most populous state and the one with the largest slice of GDP, had rarely focused policy and program attention on games, leading to the irregular doughnut shape of the industry’s geography. 32 The effect of such policy variability is clear—Victoria has seen strong 15–20 percent growth in each of the last few years, while Queensland has not grown strongly out of the downturn. The mobility and associated uncertainties faced by game workers are often forced on them by the volatility of an industry whose profile with government is equally volatile.
Policy fluctuation and failure contributes to precariousness; so does the industry’s reputation for poor management. Some of its notoriously poor working conditions can be attributed to the immaturity of the industry and the need for self-governance reform. The industry’s still overwhelmingly male-dominated production base needs to change if it is to attract the best talent, improve balance and sustainability, and capture value in a rapidly evolving consumption environment. Women and girls now account for 48 percent of all gamers. The high skew toward men and boys—more than 78 percent in the console core demographic—underlines that women are in the majority in the more casual gaming areas of the market. 33 GDAA survey data for 2014 suggests that, of the approximately eight hundred people now working in the industry, some 26 percent are women, and most of these are programmers and artists. This is beginning to align with the IGDA’s most recent survey results, which report 22 percent women employees globally in September 2014. 34
Management deficit is by no means confined to gender. Casey O’Donnell’s loving but forensic description of the “secret world of videogame creators” does not spare the industry. 35 Tacit knowledge has been poorly converted into transferable knowledge. This is a critical shortcoming because the daunting complexity of bringing together engineers, artists, designers, marketers, and managers in intense iteration can lead to crunches, “intense and extended periods of socially mandatory overtime, and a seemingly perpetual start-up environment for game development companies.” 36 There is little industry formalization and representation. Invoking the analytical work of Gina Neff and David Stark, O’Donnell asserts that the industry is in a state of “permanent beta.” Cross-disciplinary collaboration—which causes unremitting creative tension at the level of the firm and poses some of the most challenging project management tasks in contemporary industry practice—is absolutely necessary for the industry’s future. The tendency is for the industry, because of its closed opacity (and, as we have seen, because of its extreme volatility), to continually reinvent the wheel. O’Donnell stresses the great breakthrough by Unity when it made transparent authoring knowledge of great value, for example, for developing country industries. 37 All of these factors contribute to working cultures and conditions that see 50 percent leave with up to ten years exposure. 38 On the other hand, Australian industry, GDAA claims, is rare in the way it shares knowledge and resources among industry players now that the industry is composed overwhelmingly of indies. This is not typical of companies based in the United States, and was also not common when Australian developers were producing licensed IP, as a result of nondisclosure agreements.
A better articulation of the broader value of the industry to the society and economy can address precariousness. Antony Reed, an industry advocate, asserts that “this industry could make such a huge contribution if only it was understood better.” 39 Advocacy, he argues, should seek to raise awareness of, for example, the value of game design input into health and education; the transferability of games skills into mainstream IT or the burgeoning apps industry; and the highly skilled entrepreneurial games workforce, which any country should seek to retain as part of its creative class. This draws on evidence that uncertainty of work in games is mitigated to some extent by the capacity to work outside the sector (due to the high transferability of skills, particularly of programmers). There is also some evidence that companies and individuals manage precarious original IP development with sourcing licensed IP opportunities within the growing domestic apps industry, so-called serious (edutainment) games, and a small range of domestic purchasers of games products and services (sourcing licensed IP domestically can be more sustainable because it is not subject to currency fluctuation).


35.4: The Peripheral Nervous System
Skills to Develop
- Describe the organization and functions of the sympathetic and parasympathetic nervous systems
- Describe the organization and function of the sensory-somatic nervous system
The peripheral nervous system (PNS) is the connection between the central nervous system and the rest of the body. The CNS is like the power plant of the nervous system. It creates the signals that control the functions of the body. The PNS is like the wires that go to individual houses. Without those “wires,” the signals produced by the CNS could not control the body (and the CNS would not be able to receive sensory information from the body either).
The PNS can be broken down into the autonomic nervous system , which controls bodily functions without conscious control, and the sensory-somatic nervous system , which transmits sensory information from the skin, muscles, and sensory organs to the CNS and sends motor commands from the CNS to the muscles.
Autonomic Nervous System
Art Connection
Which of the following statements is false?
- The parasympathetic pathway is responsible for resting the body, while the sympathetic pathway is responsible for preparing for an emergency.
- Most preganglionic neurons in the sympathetic pathway originate in the spinal cord.
- Slowing of the heartbeat is a parasympathetic response.
- Parasympathetic neurons are responsible for releasing norepinephrine on the target organ, while sympathetic neurons are responsible for releasing acetylcholine.
The autonomic nervous system serves as the relay between the CNS and the internal organs. It controls the lungs, the heart, smooth muscle, and exocrine and endocrine glands. The autonomic nervous system controls these organs largely without conscious control; it can continuously monitor the conditions of these different systems and implement changes as needed. Signaling to the target tissue usually involves two synapses: a preganglionic neuron (originating in the CNS) synapses to a neuron in a ganglion that, in turn, synapses on the target organ, as illustrated in Figure \(\PageIndex{1}\). There are two divisions of the autonomic nervous system that often have opposing effects: the sympathetic nervous system and the parasympathetic nervous system.
Sympathetic Nervous System
The sympathetic nervous system is responsible for the “fight or flight” response that occurs when an animal encounters a dangerous situation. One way to remember this is to think of the surprise a person feels when encountering a snake (“snake” and “sympathetic” both begin with “s”). Examples of functions controlled by the sympathetic nervous system include an accelerated heart rate and inhibited digestion. These functions help prepare an organism’s body for the physical strain required to escape a potentially dangerous situation or to fend off a predator.
Most preganglionic neurons in the sympathetic nervous system originate in the spinal cord, as illustrated in Figure \(\PageIndex{2}\). The axons of these neurons release acetylcholine on postganglionic neurons within sympathetic ganglia (the sympathetic ganglia form a chain that extends alongside the spinal cord). The acetylcholine activates the postganglionic neurons. Postganglionic neurons then release norepinephrine onto target organs. As anyone who has ever felt a rush before a big test, speech, or athletic event can attest, the effects of the sympathetic nervous system are quite pervasive. This is both because one preganglionic neuron synapses on multiple postganglionic neurons, amplifying the effect of the original synapse, and because the adrenal gland also releases norepinephrine (and the closely related hormone epinephrine) into the blood stream. The physiological effects of this norepinephrine release include dilating the trachea and bronchi (making it easier for the animal to breathe), increasing heart rate, and moving blood from the skin to the heart, muscles, and brain (so the animal can think and run). The strength and speed of the sympathetic response helps an organism avoid danger, and scientists have found evidence that it may also increase LTP—allowing the animal to remember the dangerous situation and avoid it in the future.
Parasympathetic Nervous System
While the sympathetic nervous system is activated in stressful situations, the parasympathetic nervous system allows an animal to “rest and digest.” One way to remember this is to think that during a restful situation like a picnic, the parasympathetic nervous system is in control (“picnic” and “parasympathetic” both start with “p”). Parasympathetic preganglionic neurons have cell bodies located in the brainstem and in the sacral (toward the bottom) spinal cord, as shown in Figure \(\PageIndex{2}\). The axons of the preganglionic neurons release acetylcholine on the postganglionic neurons, which are generally located very near the target organs. Most postganglionic neurons release acetylcholine onto target organs, although some release nitric oxide.
The parasympathetic nervous system resets organ function after the sympathetic nervous system is activated (the common adrenaline dump you feel after a ‘fight-or-flight’ event). Effects of acetylcholine release on target organs include slowing of heart rate, lowered blood pressure, and stimulation of digestion.
Sensory-Somatic Nervous System
The sensory-somatic nervous system is made up of cranial and spinal nerves and contains both sensory and motor neurons. Sensory neurons transmit sensory information from the skin, skeletal muscle, and sensory organs to the CNS. Motor neurons transmit messages about desired movement from the CNS to the muscles to make them contract. Without its sensory-somatic nervous system, an animal would be unable to process any information about its environment (what it sees, feels, hears, and so on) and could not control motor movements. Unlike the autonomic nervous system, which has two synapses between the CNS and the target organ, sensory and motor neurons have only one synapse—one ending of the neuron is at the organ and the other directly contacts a CNS neuron. Acetylcholine is the main neurotransmitter released at these synapses.
Humans have 12 cranial nerves , nerves that emerge from or enter the skull (cranium), as opposed to the spinal nerves, which emerge from the vertebral column. Each cranial nerve is accorded a name, which are detailed in Figure \(\PageIndex{3}\). Some cranial nerves transmit only sensory information. For example, the olfactory nerve transmits information about smells from the nose to the brainstem. Other cranial nerves transmit almost solely motor information. For example, the oculomotor nerve controls the opening and closing of the eyelid and some eye movements. Other cranial nerves contain a mix of sensory and motor fibers. For example, the glossopharyngeal nerve has a role in both taste (sensory) and swallowing (motor).
Spinal nerves transmit sensory and motor information between the spinal cord and the rest of the body. Each of the 31 spinal nerves (in humans) contains both sensory and motor axons. The sensory neuron cell bodies are grouped in structures called dorsal root ganglia and are shown in Figure \(\PageIndex{4}\). Each sensory neuron has one projection—with a sensory receptor ending in skin, muscle, or sensory organs—and another that synapses with a neuron in the dorsal spinal cord. Motor neurons have cell bodies in the ventral gray matter of the spinal cord that project to muscle through the ventral root. These neurons are usually stimulated by interneurons within the spinal cord but are sometimes directly stimulated by sensory neurons.
Summary
The peripheral nervous system contains both the autonomic and sensory-somatic nervous systems. The autonomic nervous system provides unconscious control over visceral functions and has two divisions: the sympathetic and parasympathetic nervous systems. The sympathetic nervous system is activated in stressful situations to prepare the animal for a “fight or flight” response. The parasympathetic nervous system is active during restful periods. The sensory-somatic nervous system is made of cranial and spinal nerves that transmit sensory information from skin and muscle to the CNS and motor commands from the CNS to the muscles.
Art Connections
Figure \(\PageIndex{1}\): Which of the following statements is false?
- The parasympathetic pathway is responsible for relaxing the body, while the sympathetic pathway is responsible for preparing for an emergency.
- Most preganglionic neurons in the sympathetic pathway originate in the spinal cord.
- Slowing of the heartbeat is a parasympathetic response.
- Parasympathetic neurons are responsible for releasing norepinephrine on the target organ, while sympathetic neurons are responsible for releasing acetylcholine.
- Answer
-
D
Glossary
- acetylcholine
- neurotransmitter released by neurons in the central nervous system and peripheral nervous system
- autonomic nervous system
- part of the peripheral nervous system that controls bodily functions
- cranial nerve
- sensory and/or motor nerve that emanates from the brain
- norepinephrine
- neurotransmitter and hormone released by activation of the sympathetic nervous system
- parasympathetic nervous system
- division of autonomic nervous system that regulates visceral functions during rest and digestion
- sensory-somatic nervous system
- system of sensory and motor nerves
- spinal nerve
- nerve projecting between skin or muscle and spinal cord
- sympathetic nervous system
- division of autonomic nervous system activated during stressful “fight or flight” situations


<IP_ADDRESS>: Kitchen Cleaning Tasks
The kitchen should be cleaned after every use. Home Health Aides/Personal Care Aides should encourage family members to do the same.
Kitchen tasks :
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Wash dishes immediately after use
- Dishes should be washed in hot soapy water using dish detergent.
- Air dry washed dishes and pots rather than using a dishtowel to save time.
- If using a dishwasher, learn how to properly use it. Dishwashers can also be used to sterilize items. Some dishwashers require food to be scraped and plates to be rinsed before loading. Many items cannot be washed in a dishwasher, such as electrical appliances, china, crystal, and cast iron. Always check with the patient.
- Put dishes away after they have air dried.
- Clean the kitchen sink and faucet with a scouring or specialty cleaner once per day.
- Wipe and clean surfaces as you work and at least once per day.

- Sweep the kitchen floor daily and mop at least once per week, or more if needed. Ensure the floor is dry to prevent falls .
- Stove tops should be cleaned with hot soapy water, an all-purpose or a specialty cleaner. Find out the appropriate type of cleaner to use.
- Ovens are cleaned periodically. Some ovens are self-cleaning while others require direct cleaning with a specialty oven cleaner. Be cautious to use rubber gloves and to not inhale oven cleaner as fumes can be toxic. Ensure no children or pets are around when using oven cleaner as ingestion of the cleaner can be deadly .
- Clean out the refrigerator once per week. Discard items that are spoiled. Wipe surfaces of spills and crumbs. Ensure food is properly spaced in the refrigerator to allow good air circulation.
- Wipe the refrigerator door and any spills inside once per day.
- Defrost the freezer when necessary. When defrosting, all food should be removed and stored in a cooler to keep it cool and prevent spoilage. Follow the manufacturer’s instructions on how to defrost the specific unit a patient has.
- Clean inside cabinets, drawers, and cupboards once or twice per year, or as needed.
True or False
1. When using an oven cleaner, make sure you wear gloves and that no pets or children are around as the cleaner can be deadly if ingested. True or False? ______
Multiple Choice
2. How often should counter and stove tops be cleaned?
a). Once per week
b). Twice per week
c). Any time they are dirty and at least once per day
d). That’s not my job!
- Answer
-
1. True
2. C
FEEDBACK :
1. When using an oven cleaner gloves should always be worn. Oven cleaner should never be used when children or pets are around as the fumes and the cleaner may be toxic and could be fatal if ingested.
2. Counter and stove tops should be cleaned any time they are dirty and at least once per day. It is easier to remove spills as soon as they happen than to clean them once they have dried. This will help to save time.


31.6: Chapter Summary
TIC is a therapeutic approach that centers on the understanding that trauma can have long-lasting emotional, neurological, psychological, social, and biological effects. It acknowledges that ACEs can significantly impact present and future health. A TIC-informed approach uses six guiding principles to ensure every client interaction is mindful and places the client’s well-being first; the client is not harmed further or retraumatized by working on their past. A trauma-informed approach requires the nurse’s constant attention, caring awareness, and sensitivity.
The U.S. health care system is overburdened with the rise in mental health issues. Mental health services are insufficient to address clients’ needs.  As trusted advocates, nurses are uniquely positioned to recognize mental health concerns, provide compassion to clients, and help clients access treatment. Nurses must establish a therapeutic nurse-client relationship. Understanding who the client is, what is occurring in their life, what resources are available to them, and their individual beliefs, supports, and demeanor can help a nurse determine if a client is at risk for ineffective coping and possible progression to crisis.
Deaths from SUDs, particularly with opioid overdoses, have increased dramatically in recent years. The opioid epidemic has many causes including the notable increase in opioid prescriptions, rise in heroin use, and availability of illicitly manufactured fentanyl. This public health crisis spawns various socioeconomic and health consequences affecting all populations. Public health initiatives must address social determinants of health that cause systematic inequalities, barriers to health care access, and the promotion of stigma. A unified approach is needed to address associated mental disorders and SUDs. Nurses are poised to make a distinct difference in effecting change in vulnerable individuals, communities, and populations impacted by the opioid epidemic. Evidence-based strategies must include early identification, evidence-based interventions, harm-reduction programs, recovery services, and advocacy for policies to combat this public health epidemic.
Every year, millions of men, women, and children are trafficked worldwide. This often-hidden crime can happen in any community and to individuals of any age, race, gender, or nationality. Human trafficking is committed against a person’s will, and the economic sectors that profit the most include agriculture, restaurants, manufacturing, domestic work, entertainment, hospitality, and the commercial sex industry. Language barriers, fear of their traffickers, and/or fear of law enforcement frequently keep victims from seeking help. Health care encounters with nurses may be one of the only channels through which a victim is identified. The nurse’s ability to identify a victim and knowledge of the available resources to assist a victim can be lifesaving for some victims.
Refugees and asylum seekers have left their homes, fleeing persecution due to race, national origin, religion, political opinion, or membership in a particular social group. This population faces many risks and dangers, including disease, malnutrition, violence, labor exploitation, and trafficking. Poor living conditions and inadequate hygiene make refugees vulnerable to many health conditions. Overcrowding, poor water and sanitation conditions, lack of vaccinations, delayed diagnosis, and reduced access to treatment can lead to increased occurrence, severity, and case fatality of infectious diseases. Nurses treating this population should offer screening for infectious diseases and determine vaccination status. Some clients may need additional health education in an appropriate language to understand their options. Specialist client support organizations may also be able to assist.


1.1: Pharmacology, Interdisciplinary Teams, and Nursing Practice
By the end of this section, you should be able to:
- 1.1.1 Define pharmacology.
- 1.1.2 Identify key events in the history of pharmacology.
- 1.1.3 Discuss the interdisciplinary nature of pharmacology and client care.
- 1.1.4 Explain the importance of pharmacology in nursing practice.
History of Pharmacology
The word pharmacology (from two Greek words, pharmakon , which means “ drug ” or “medicine,” and logos , which means “study”) essentially means the study of medicine; it could also be described as the study of the biological effects of chemicals on the body. The history of pharmacology dates back thousands of years, most likely beginning with the use of medicinal plants and herbs to relieve symptoms of various diseases. Herbal medications have been used in medicine in most civilizations around the globe dating back to ancient times. One generation passed its knowledge to the next through oral tradition. Individuals might not know how a treatment worked, but they were able to observe its effects.
The word drug may originate from an old Dutch word, droog , which means dry, or an old French term, drogue . This may have referred to “dry barrels,” the method for preserving medicinal plants as dry matter or any substance, such as animal products or inorganic materials, used in the composition of medicines. The words drug and medication are used interchangeably throughout this text.
More than 2,000 years ago in China, Greece, and Egypt, poultices composed of moldy bread were used to treat open wounds. (Was it possible that this had antimicrobial effects?) This treatment was documented in the Ebers papyrus (see Figure 1.2), one of the world’s oldest preserved medical documents, in 1550 BCE. Medicinal soils were used at that time as well. An Anglo-Saxon recipe has been found that dates back 1,000 years ago, and it was recently discovered that it is helpful in the treatment of methicillin-resistant Staphylococcus aureus (Hutchings et al., 2019) .
It is true that although many treatments or remedies were simply ineffective, others unfortunately were poisonous. However, some treatments did contain substances that worked. Opium, from the poppy plant, has been used for centuries to relieve pain and for sedation by the Sumerians and the Greeks. However, the first authentic use was recorded by the Greek philosopher Theophrastus in the 3rd century BCE (Stefano et al., 2017).
The London Pharmacopoeia , first published in 1618, contained over 1,000 simple drugs and over 900 preparations and compounds. Progress in the use of pharmacological treatments continued to develop worldwide at differing rates, but in the late 1700s, several advances in Europe were made that remain significant today. William Withering in England developed digitalis, a derivative from the foxglove plant, which was and still is used in treating heart disease and rhythm disorders. Foxglove had been used for centuries in folk medicine, but Withering was able to use small amounts of the foxglove leaves for the treatment of dropsy (now known as heart failure). Another advancement occurred in 1796 when Edward Jenner developed the first vaccine against smallpox. His work established that infectious diseases could be controlled with the deliberate use of vaccination.
The era of modern pharmacology began approximately 200 years ago. Even in the early 1800s, chemists could isolate various chemicals from substances and mixtures. In 1804 or 1805, Fredrich Serturner isolated morphine from opium, which is still used for treating severe pain (Kumar, 2022). Once scientists could isolate the drugs from plants and other natural resources, they could better study their actions on the body. Most often, these experiments were conducted on animals, but occasionally the chemists would test the drug on themselves or on friends and family, sometimes with disastrous results. The first school of pharmacy was established in 1847 in the country of Estonia. The oldest pharmacology journal, Naunyn-Schmeideberg’s Archives of Pharmacology , was first published in 1873 and is still being published today (Hattori & Seifert, 2023).
Scientists in the 1890s developed aspirin from the bark of the willow tree, using it to treat fevers and mild discomfort. The link between diabetes mellitus and the pancreas was established in 1889 through the work of Joseph von Mering and Oskar Minkowski. Approximately 30 years later, in 1921, Frederick Banting and Charles Best formulated the first insulin preparation (Karamanou et al., 2016; Lee & Yoon, 2021). Paul Ehrlich introduced the first treatment for syphilis in 1909 by isolating a chemical compound that could be used against a microorganism (arsphenamine, or compound 606). Arsphenamine is a derivative of arsenic, and although it could successfully treat syphilis, it did have potentially fatal side effects, which caused it to fall out of use quickly. Shortly after that, in 1928, Alexander Fleming discovered that Penicillium notatum mold prevented the growth of Staphylococcus aureus and ushered in the era of antibiotic use. Millions of lives have been saved since then by using antibiotics to treat infectious diseases such as pneumonia, sepsis, gangrene, scarlet fever, syphilis, gonorrhea, meningitis, and tuberculosis.
Although plants and natural resources are still used today, they can be a finite resource. The development of new medicines has continued to evolve with the synthesis of drugs in the laboratory and the use of biomolecules or biologics . (Biologics will be discussed in further detail later in this chapter.) There have been tremendous strides in the development of medications that have revolutionized (and will continue to revolutionize) the treatment of disease and our understanding of the human body.
Interdisciplinary Nature of Pharmacology
The nurse administers medication as part of a team that includes other professions. The health care provider (physician, physician’s assistant, or nurse practitioner) orders the drug indicated to treat the client. (The term client is interchangeable with patient in some settings.) The pharmacist evaluates the client and their situation and verifies the appropriateness of the requested medication and its dose for the client. Then, the pharmacist may dispense the medication, recommend the appropriate time for administration, and complete teaching to the client. In the hospital setting, the nurse assesses the client and the potential effects of the medication and then administers the drug after determining the safety to the client. A social worker may become involved if issues of non-adherence to the medication regimen are found or if the client cannot afford the drug once discharged from the hospital. These are just a few of the health care roles involved in the pharmacological care of the client, and often these roles overlap in practice. Communication between professions is crucial in delivering the best care to the client. The concept of collaborative practice , also known as interprofessional (IP) collaboration , within health care professions is viewed as “best practice” because inadequate collaboration may adversely affect the delivery of health care and the safety of the client. More efficient use of resources also results from IP teamwork.
Health care providers should understand each other’s roles to prevent mistakes. Competence in interprofessional collaboration is crucial for effective teamwork among physicians, nurses, pharmacists, and others. Interprofessional teamwork improves the efficiency of client care, helps lower costs to the client and the institution, improves client outcomes, and enhances the delivery of holistic care. It also boosts job satisfaction and reduces staff burnout. Maintaining competency includes understanding team goals, having a shared identity, and committing to safe client care while relying on mutual respect and trust. Effective communication and decision-making involves active listening and embracing each discipline’s roles in client care.
Pharmacology and Clinical Nursing Practice
Knowledge about pharmacology and the various drugs prescribed and administered to clients is a major part of the nurse’s role. Even when not administering the medications directly to the client, it is crucial to the client’s care. Nurses must understand the pharmacotherapeutic effects of the drugs in their clinical practice. Drugs have intended or therapeutic effects —these are effects that are expected and desired from that particular medication. However, drugs may also have undesirable adverse effects or side effects .
There are thousands of drugs on the market. Although the nurse is usually responsible for a much smaller number of medications in a specialty area, it is still a significant task to be responsible for the consequences of administering several drugs to various clients with an assortment of diseases. A few of the nurse’s responsibilities as they relate to medication administration are listed here (also see Drug Administration for additional information):
- Incorporating the nursing process (assessment, nursing diagnoses, planning, implementation, and evaluation) and clinical judgment into medication administration
- Knowledge of the client and their disease process (or the prevention of disease)
- Knowledge of the drug’s name (both generic and brand [trade] names)
- Understanding the indication for the drug (why the client has been prescribed this drug)
- Appropriateness of the drug ordered by the provider
- Assessment of the client prior to administering the drug
- Determining which focused assessments show that the drug is safe for each client
- Understanding which abnormal lab values would prohibit this drug from being given to a specific client
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Special considerations:
- Life phase (e.g., pediatric , pregnancy , or geriatric populations)
- Body weight
- Nutritional status
- Pathophysiology of the disease process
- Race and ethnicity
- Determining the safety of the drug in the client
- Contraindications to the use of a drug in a particular client
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Administering the drug(s) using the seven “rights,” which are as follows:
- Right client
- Right medication
- Right indication
- Right dosage range and rate of administration (if appropriate)
- Right route
- Right time
- Right documentation
- Monitoring for potential drug interactions
- Assessment of the therapeutic and adverse effects of the drug
- Education of the client and family (or caregivers) about the disease process, drugs prescribed, and therapeutic and adverse effects
Follow-up with the client is critical to their safety and well-being. The nursing care plan will need to be modified if goals are not reached, and this may need to be done in collaboration with other health care team members. Communication between interprofessional team members is key to preventing adverse drug event s . The nurse should allow plenty of time to counsel the client about the prescribed drugs and speak clearly, using simple language that avoids medical jargon. It is helpful to have the client repeat the instructions back to the nurse to assess understanding.


13.4: Types of Outliers in Linear Regression
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In this section, we identify criteria for determining which outliers are important and influential. Outliers in regression are observations that fall far from the "cloud" of points. These points are especially important because they can have a strong influence on the least squares line.
Example \(\PageIndex{1}\)
There are six plots shown in Figure \(\PageIndex{1}\) along with the least squares line and residual plots. For each scatter plot and residual plot pair, identify any obvious outliers and note how they influence the least squares line. Recall that an outlier is any point that doesn't appear to belong with the vast majority of the other points.
- There is one outlier far from the other points, though it only appears to slightly influence the line.
- There is one outlier on the right, though it is quite close to the least squares line, which suggests it wasn't very influential.
- There is one point far away from the cloud, and this outlier appears to pull the least squares line up on the right; examine how the line around the primary cloud doesn't appear to t very well.
- There is a primary cloud and then a small secondary cloud of four outliers. The secondary cloud appears to be influencing the line somewhat strongly, making the least square line t poorly almost everywhere. There might be an interesting explanation for the dual clouds, which is something that could be investigated.
- There is no obvious trend in the main cloud of points and the outlier on the right appears to largely control the slope of the least squares line.
- There is one outlier far from the cloud, however, it falls quite close to the least squares line and does not appear to be very influential.
Examine the residual plots in Figure \(\PageIndex{1}\). You will probably nd that there is some trend in the main clouds of (3) and (4). In these cases, the outliers influenced the slope of the least squares lines. In (5), data with no clear trend were assigned a line with a large trend simply due to one outlier (!).
Definition: Leverage
Points that fall horizontally away from the center of the cloud tend to pull harder on the line, so we call them points with high leverage.
Points that fall horizontally far from the line are points of high leverage; these points can strongly influence the slope of the least squares line. If one of these high leverage points does appear to actually invoke its influence on the slope of the line (as in cases (3), (4), and (5) of Example \(\PageIndex{1}\)) then we call it an influential point . Usually we can say a point is influential if, had we plotted the line without it, the influential point would have been unusually far from the least squares line.
It is tempting to remove outliers. Do not do this without a very good reason. Models that ignore exceptional (and interesting) cases often perform poorly. For instance, if a financial firm ignored the largest market swings - the "outliers" - they would soon go bankrupt by making poorly thought-out investments.
Caution: Don't ignore outliers when fitting a final model
If there are outliers in the data, they should not be removed or ignored without a good reason. Whatever final model is fit to the data would not be very helpful if it ignores the most exceptional cases.
Caution: Outliers for a categorical predictor with two levels
Be cautious about using a categorical predictor when one of the levels has very few observations. When this happens, those few observations become inuential points.


4.1: Fundamentals I/O- handshake and buffering
Introduction
This section introduces the learner to the various strategies used in I/O interfaces and other operations possible on an interface
Activity details
The computer is useless without some kind of interface to to the outside world. There are many different devices which we can connect to the computer system; keyboards, VDUs and disk drives are some of the more familiar ones. Irrespective of the details of how such devices are connected we can say that all I/O is governed by three basic strategies.
- Programmed I/O
- Interruptdriven I/O
- Direct Memory Access (DMA)
In programmed I/O all data transfers between the computer system and external devices are completely controlled by the computer program. Part of the program will check to see if any external devices require attention and act accordingly. This process is known as polling. Programmed I/O is probably the most common I/O technique because it is very cheap and easy to implement, and in general does not introduce any unforeseen hazards.
Programmed I/O
Is a method of transferring data between the CPU and a peripheral, such as a network adapter or an ATA storage device. In general, programmed I/O happens when software running on the CPU uses instructions that access I/O address space to perform data transfers to or from an I/O device.
The PIO interface is grouped into different modes that correspond to different transfer rates. The electrical signaling among the different modes is similar — only the cycle time between transactions is reduced in order to achieve a higher transfer rate
The PIO modes require a great deal of CPU overhead to configure a data transaction and transfer the data. Because of this inefficiency, the DMA (and eventually UDMA) interface was created to increase performance. The simple digital logic required to implement a PIO transfer still makes this transfer method useful today, especially if high transfer rates are not required like in embedded systems, or with FPGA chips where PIO mode can be used without significant performance loss.
Interrupt driven I/O
Is a way of controlling input/output activity in which a peripheral or terminal that needs to make or receive a data transfer sends a signal that causes a program interrupt to be set. At a time appropriate to the priority level of the I/O interrupt, relative to the total interrupt system, the processor enters an interrupt service routine (ISR). The function of the routine will depend upon the system of interrupt levels and priorities that is implemented in the processor.
In a single-level single-priority system there is only a single I/O interrupt – the logical OR of all the connected I/O devices. The associated interrupt service routine polls the peripherals to find the one with the interrupt status set.
Handshaking
Handshaking is a I/O control method to synchronize I/O devices with the microprocessor. As many I/O devices accepts or release information at a much slower rate than the microprocessor, this method is used to control the microprocessor to work with a I/O device at the I/O devices data transfer rate.
Handshaking is an automated process of negotiation that dynamically sets parameters of a communications channel established between two entities before normal communication over the channel begins. It follows the physical establishment of the channel and precedes normal information transfer. The handshaking process usually takes place in order to establish rules for communication when a computer sets about communicating with a foreign device. When a computer communicates with another device like a modem, printer, or network server, it needs to handshake with it to establish a connection.
Handshaking can negotiate parameters that are acceptable to equipment and systems
at both ends of the communication channel, including information transfer rate, coding alphabet, parity, interrupt procedure, and other protocol or hardware features. Handshaking is a technique of communication between two entities. However, within TCP/IP RFCs, the term “handshake” is most commonly used to reference the TCP three-way handshake. For example, the term “handshake” is not present in RFCs covering FTP or SMTP. One exception is Transport Layer Security, TLS, setup, FTP RFC 4217. In place of the term “handshake”, FTP RFC 3659 substitutes the term “conversation” for the passing of commands.
A simple handshaking protocol might only involve the receiver sending a message meaning “I received your last message and I am ready for you to send me another one.” A more complex handshaking protocol might allow the sender to ask the receiver if it is ready to receive or for the receiver to reply with a negative acknowledgement meaning “I did not receive your last message correctly, please resend it” (e.g., if the data was corrupted en route).
Handshaking facilitates connecting relatively heterogeneous systems or equipment over a communication channel without the need for human intervention to set parameters.
Example: Supposing that we have a printer connected to a system. The printer can print 100 characters/second, but the microprocessor can send much more information to the printer at the same time. That’s why, just when the printer gets it enough data to print it places a logic
1 signal at its Busy pin, indicating that it is busy in printing. The microprocessor now tests the busy bit to decide if the printer is busy or not. When the printer will become free it will change the busy bit and the microprocessor will again send enough amounts of data to be printed. This process of interrogating the printer is called handshaking.
Buffering
Is the process of transferring data between a program and an external device, The process of optimizing I/O consists primarily of making the best possible use of the slowest part of the path between the program and the device. The slowest part is usually the physical channel, which is often slower than the CPU or a memory-to-memory data transfer. The time spent in I/O processing overhead can reduce the amount of time that a channel can be used, thereby reducing the effective transfer rate. The biggest factor in maximizing this channel speed is often the reduction of I/O processing overhead.
A buffer is a temporary storage location for data while the data is being transferred. A buffer is often used for the following purposes:
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Small I/O requests can be collected into a buffer, and the overhead of making many relatively expensive system calls can be greatly reduced.
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A collection buffer of this type can be sized and handled so that the actual physical I/O requests made to the operating system match the physical characteristics of the device being used.
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Many data file structures, such as the f77 and cos file structures, contain control words. During the write process, a buffer can be used as a work area where control words can be inserted into the data stream (a process called blocking). The blocked data is then written to the device. During the read process, the same buffer work area can be used to examine and remove these control words before passing the data on to the user (deblocking ).
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When data access is random, the same data may be requested many times. A cache is a buffer that keeps old requests in the buffer in case these requests are needed again. A cache that is sufficiently large and/or efficient can avoid a large part of the physical I/O by having the data ready in a buffer. When the data is often found in the cache buffer, it is referred to as having a high hit rate. For example, if the entire file fits in the cache and the file is present in the cache, no more physical requests are required to perform the I/O. In this case, the hit rate is 100%.
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Running the disks and the CPU in parallel often improves performance; therefore, it is useful to keep the CPU busy while data is being moved. To do this when writing, data can be transferred to the buffer at memory-to- memory copy speed and an asynchronous I/O request can be made. The control is then immediately returned to the program, which continues to execute as if the I/O were complete (a process called write-behind). A similar process can be used while reading; in this process, data is read into a buffer before the actual request is issued for it. When it is needed, it is already in the buffer and can be transferred to the user at very high speed. This is another form or use of a cache.
Conclusion
This section introduced the learner to the various ways, interfaces access and pass data. They include polling, interrupt and DMA. In them, speed between the different devices connected to the CPU are synchronized to be able to communicate effectively
Assessment
1. What is the difference between programmed-driven I/O and interrupt-driven I/O?
Programmed-driven I/O means the program is polling or checking some hardware item e.g. mouse within a loop.
For Interrupt driven I/O, the same mouse will trigger a signal to the program to process the mouse event.
2. What is one advantage and one disadvantage of each?
Advantage of Programmed Driven: easy to program and understand
Disadvantages: slow and inefficient
Advantage of Interrupt Driven: fast and efficient
Disadvantage: Can be tricky to write if you are using a low level language.
Can be tough to get the various pieces to work well together. Usually done by the hardware manufacturer or the OS maker e.g. Microsoft.


2.1.0: The Rectangular Coordinate Systems and Graphs (Exercises)
For the following exercises, find the \(x\) -intercept and the \(y\) -intercept without graphing.
1. \(4 x-3 y=12\)
2. \(2 y-4=3 x\)
For the following exercises, solve for \(y\) in terms of \(x\), putting the equation in slope-intercept form.
3. \(5 x=3 y-12\)
4. \(2 x-5 y=7\)
For the following exercises, find the distance between the two points.
5. (-2,5)(4,-1)
6. (-12,-3)(-1,5)
7. Find the distance between the two points (-71,432) and (511,218) using your calculator, and round your answer to the nearest thousandth.
For the following exercises, find the coordinates of the midpoint of the line segment that joins the two given points.
8. (-1,5) and (4,6)
9. (-13,5) and (17,18)
For the following exercises, construct a table and graph the equation by plotting at least three points.
10. \(y=\frac{1}{2} x+4\)
11. \(4 x-3 y=6\)


6.1: Event Horizons
One seemingly trivial way to generate solutions to the field equations in vacuum is simply to start with a flat Lorentzian spacetime and do a change of coordinates. This might seem pointless, since it would simply give a new description (and probably a less convenient and descriptive one) of the same old, boring, flat spacetime. It turns out, however, that some very interesting things can happen when we do this.
The Event Horizon of an Accelerated Observer
Consider the uniformly accelerated observer described in example 4 and example 19 . Recalling these earlier results, we have for the ship’s equation of motion in an inertial frame
\[x = \frac{1}{a} (\sqrt{1 + a^{2} t^{2}} - 1),\]
and for the metric in the ship’s frame
\[\begin{align} g'_{t' t'} &= (1 + ax')^{2} \\ g'_{x' x'} &= -1 \ldotp \end{align}\]
Since this metric was derived by a change of coordinates from a flat-space metric, and the Ricci curvature is an intrinsic property, we expect that this one also has zero Ricci curvature . This is straightforward to verify. The nonvanishing Christoffel symbols are
\[\Gamma^{t'}_{x' t'} = \frac{a}{1 + ax'} \]
and
\[\Gamma^{x'}_{t' t'} = a (1 + ax') \ldotp\]
The only elements of the Riemann tensor that look like they might be nonzero are \(R^{t'}_{t'x'x'}\) and \(R^{x'}_{t'x't'}\), but both of these in fact vanish.
Exercise \(\PageIndex{1}\)
Self-check: Verify these facts.
This seemingly routine exercise now leads us into some very interesting territory. Way back in section 1.1 , we conjectured that not all events could be time-ordered: that is, that there might exists events in spacetime 1 and 2 such that 1 cannot cause 2, but neither can 2 cause 1. We now have enough mathematical tools at our disposal to see that this is indeed the case.
We observe that x(t) approaches the asymptote \(x = \frac{t−1}{a}\). This asymptote has a slope of 1, so it can be interpreted as the world-line of a photon that chases the ship but never quite catches up to it. Any event to the left of this line can never have a causal relationship with any event on the ship’s world-line. Spacetime, as seen by an observer on the ship, has been divided by a curtain into two causally disconnected parts. This boundary is called an event horizon . Its existence is relative to the world-line of a particular observer. An observer who is not accelerating along with the ship does consider an event horizon to exist. Although this particular example of the indefinitely accelerating spaceship has some physically implausible features (e.g., the ship would have to run out of fuel someday), event horizons are real things. In particular, we will see in section 6.3 that black holes have event horizons.
Interpreting everything in the (t', x') coordinates tied to the ship, the metric’s component g' t't' vanishes at \(x' = − \frac{1}{a}\). An observer aboard the ship reasons as follows. If I start out with a head-start of \(\frac{1}{a}\) relative to some event, then the timelike part of the metric at that event vanishes. If the event marks the emission of a material particle, then there is no possible way for that particle’s world-line to have \(ds^2 > \)0. If I were to detect a particle emitted at that event, it would violate the laws of physics, since material particles must have \(ds^2 > 0\), so I conclude that I will never observe such a particle. Since all of this applies to any material particle, regardless of its mass m, it must also apply in the limit \(m → 0\), i.e., to photons and other massless particles. Therefore I can never receive a particle emitted from this event, and in fact it appears that there is no way for that event, or any other event behind the event horizon, to have any effect on me. In my frame of reference, it appears that light cones near the horizon are tipped over so far that their future light-cones lie entirely in the direction away from me.
We’ve already seen in Example 14 that a naive Newtonian argument suggests the existence of black holes; if a body is sufficiently compact, light cannot escape from it. In a relativistic treatment, this should be described as an event horizon .
Information Paradox
The existence of event horizons in general relativity has deep implications, and in particular it helps to explain why it is so difficult to reconcile general relativity with quantum mechanics, despite nearly a century of valiant attempts. Quantum mechanics has a property called unitarity. Mathematically, this says that if the state of a quantum mechanical system is given, at a certain time, in the form of a vector, then its state at some point in the future can be predicted by applying a unitary matrix to that vector. A unitary matrix is the generalization to complex numbers of the ordinary concept of an orthogonal matrix, and essentially it just represents a change of basis, in which the basis vectors have unit length and are perpendicular to one another.
To see what this means physically, consider the following nonexamples. The matrix
\[\begin{pmatrix} 1 & 0 \\ 0 & 0 \end{pmatrix}\]
is not unitary, because its rows and columns are not orthogonal vectors with unit lengths. If this matrix represented the time-evolution of a quantum mechanical system, then its meaning would be that any particle in state number 1 would be left alone, but any particle in state 2 would disappear. Any information carried by particles in state 2 is lost forever and can never be retrieved. This also violates the time-reversal symmetry of quantum mechanics.
Another nonunitary matrix is:
\[\begin{pmatrix} 1 & 0 \\ 0 & \sqrt{2} \end{pmatrix}\]
Here, any particle in state 2 is increased in amplitude by a factor of \(\sqrt{2}\), meaning that it is doubled in probability. That is, the particle is cloned. This is the opposite problem compared to the one posed by the first matrix, and it is equally problematic in terms of timereversal symmetry and conservation of information. Actually, if we could clone a particle in this way, it would violate the Heisenberg uncertainty principle. We could make two copies of the particle, and then measure the position of one copy and the momentum of the other, each with unlimited precision. This would violate the uncertainty principle, so we believe that it cannot be done. This is known as the no-cloning theorem. 1
Note
Ahn et al. have shown that the no-cloning theorem is violated in the presence of closed timelike curves: arxiv.org/abs/1008.0221v1
The existence of event horizons in general relativity violates unitarity, because it allows information to be destroyed. If a particle is thrown behind an event horizon, it can never be retrieved.
Radiation from Event Horizons
In interesting twist on the situation was introduced by Bill Unruh in 1976. Observer \(B\) aboard the accelerating spaceship believes in the equivalence principle, so she knows that the local properties of space at the event horizon would seem entirely normal and Lorentzian to a local observer \(A\). (The same applies to a black hole’s horizon.) In particular, \(B\) knows that \(A\) would see pairs of virtual particles being spontaneously created and destroyed in the local vacuum. This is simply a manifestation of the time-energy form of the uncertainty principle, \(\Delta E \Delta t \le h\). Now suppose that a pair of particles is created, but one is created in front of the horizon and one behind it. To \(A\), these are virtual particles that will have to be annihilated within the time \(\Delta\)t, but according to \(B\) the one created in front of the horizon will eventually catch up with the spaceship, and can be observed there, although it will be red-shifted. The amount of redshift is given by
\[\sqrt{g'_{t' t'}} = \sqrt{(1+ax')^{2}}.\]
Say the pair is created right near the horizon, at \(x' = − \frac{1}{a}\). By the uncertainty principle, each of the two particles is spread out over a region of space of size \(\Delta x'\). Since these are photons, which travel at the speed of light, the uncertainty in position is essentially the same as the uncertainty in time. The forward-going photon’s redshift comes out to be a\(\Delta\)x' = a\(\Delta\)t', which by the uncertainty principle should be at least \(\frac{ha}{E}\), so that when the photon is observed by B, its energy is
\[E(\frac{ha}{E}) = ha.\]
Now B sees a uniform background of photons, with energies of around ha, being emitted randomly from the horizon. They are being emitted from empty space, so it seems plausible to believe that they don’t encode any information at all; they are completely random. A surface emitting a completely random (i.e., maximum-entropy) hail of photons is a black-body radiator, so we expect that the photons will have a black-body spectrum, with its peak at an energy of about ha. This peak is related to the temperature of the black body by E ∼ kT, where k is Boltzmann’s constant. We conclude that the horizon acts like a black-body radiator with a temperature T ∼ \(\frac{ha}{k}\). The more careful treatment by Unruh shows that the exact relation is \(T = \frac{ha}{4 \pi^{2} k}\), or \(\frac{ha}{4 \pi^{2} kc}\) in SI units.
An important observation here is that not only do different observers disagree about the number of quanta that are present (which is true in the case of ordinary Doppler shifts), but about the number of quanta in the vacuum as well. B sees photons that according to A do not exist.
Let’s consider some real-world examples of large accelerations:
| acceleration (m/s 2 ) | temperature of horizon (K) | |
|---|---|---|
| bullet fired from a gun | 10 3 | 10 -17 |
| electron in a CRT | 10 7 | 10 -13 |
| plasmas produced by intense laser pulses | 10 21 | 10 |
| proton in a helium nucleus | 10 27 | 10 8 |
To detect Unruh radiation experimentally, we would ideally like to be able to accelerate a detector and let it detect the radiation. This is clearly impractical. The third line shows that it is possible to impart very large linear accelerations to subatomic particles, but then one can only hope to infer the effect of the Unruh radiation indirectly by its effect on the particles. As shown on the final line, examples of extremely large nonlinear accelerations are not hard to find, but the interpretation of Unruh radiation for nonlinear motion is unclear. A summary of the prospects for direct experimental detection of this effect is given by Rosu. 2 This type of experiment is clearly extremely difficult, but it is one of the few ways in which one could hope to get direct empirical insight, under controlled conditions, into the interface between gravity and quantum mechanics.


2.6: Discussion- Human Resource Strategy and Planning
When an organization looks at competitive differentiation, costs of doing business, they do SWOT and SOFT analyses, all as a part of determining the strategic direction of the business. As the leader of the organization’s human resources department, you will be developing your own strategy, which will provide direction to your group on how your team will support the overall goals of the company.
You work for a small-box retailer that’s a little late getting into the ecommerce space. Now, the company wants to move quickly from a “bricks-and-mortar” only approach to one that embraces omnichannel retailing. Why? Because the competition is eating their lunch!
Currently, the company’s website is barely a page or two. One page features an “about the company” area and a list of store locations. As an HR leader, you have a recruiting page on it and a link to your application system, but that’s about it. Ecommerce and omnichannel retailing seem light years away, but the company’s five-year plan calls for it to be up and running in short order.
Discussion Prompt
We know you’re not an ecommerce professional or a retail professional and, hey, you’ve only gotten into the second module of HR management. That aside, we still think you have what it takes to help save this company! You’re going to use what you know about human resources strategy planning—that is, attracting talent, building high performance work organizations and aligning people with the business—to support the company’s efforts to get into omnichannel retailing.
Write down at least three ideas and plans for each one of those strategic areas. Research other companies that are getting into or trying to get into the ecommerce space to support your ideas and try to anticipate issues for your company by understanding what others have experienced. Once you’ve completed your paper, share it with two classmates to get their thoughts. Offer your thoughts on the papers of two classmates as well.
Grading
Share your opinions below and respond to two of your classmates’ thoughts.
| Criteria | Not Evident | Developing | Exemplary | Points |
|---|---|---|---|---|
| Submit your initial response |
0 pts
No post made |
5 pts
Post is either late or off-topic |
10 pts
Post is made on time and is focused on the prompt |
10 pts |
| Respond to at least two peers’ presentations |
0 pts
No response to peers |
2
pts
Responded to only one peer |
5 pts
Responded to two peers |
5 pts |
| Total: | 15 pts |


20.1: Wound Care Introduction
- Assess tissue condition, wounds, drainage, and pressure injuries
- Cleanse and irrigate wounds
- Apply a variety of wound dressings
- Obtain a wound culture specimen
- Use appropriate aseptic or sterile technique
- Explain procedure to patient
- Adapt procedures to reflect variations across the life span
- Recognize and report significant deviations in wounds
- Document actions and observations
Wound healing is a complex physiological process that restores function to skin and tissue that have been injured. The healing process is affected by several external and internal factors that either promote or inhibit healing. When providing wound care to patients, nurses, in collaboration with other members of the health care team, assess and manage external and internal factors to provide an optimal healing environment. [1]
Complex wounds often require care by specialists. Certified wound care nurses assess, treat, and create care plans for patients with complex wounds, ostomies, and incontinence conditions. They act as educators and consultants to staff nurses and other healthcare professionals. This chapter will discuss wound care basics for entry-level nurses. Request a consultation by a certified wound care nurse when caring for patients with complex or nonhealing wounds.
- Cox, J. (2019). Wound care 101. Nursing , 49 (10). https://doi.org/10.1097/01.nurse.0000580632.58318.08 ↵


6.1: NAEYC Standards
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The following NAEYC Standard for Early Childhood Professional Preparation addressed in this chapter:
The following competencies are addressed in this chapter:
The following elements of the code are touched upon in this chapter:
Section I: Ethical Responsibilities to Children
Ideals: – I-1.1-, I-1.2, I-1.3, I-1.6, I-1.7, I-1.10
Principles: P-1.1, P-1.2, P-1.4, P-1.5, P-6, P-1.7,
Section II: Ethical Responsibilities to Families
Ideals: I-2.1, I-2.2, I-2.3, I-2.4, I-2.5, I-2.6, I-2.7, I-2.8
Principles: P-2.4, P-2.6, P-2.7, P-2.8, P-2.12, P-2.13
Ethical Responsibilities to Colleagues (Co-Workers and Employers)
Ideals: I-3A.3, I-3B.1
Section IV: Ethical Responsibilities to Community and Society
Ideals: I-4.1, I-4.2, I-4.5


7.3: Overview- Drafting and Writing a Paper
The next step in the writing journey is drafting and writing the paper. A draft is a complete version of a piece of writing, but it is not the final version . After you draft a paper, you will have the opportunity to revise it, and then to edit and proofread it (as detailed in Chapter 8 ). The first draft gives you a working version that you will later improve.
Basic elements of a first draft
The previous chapter taught you how to develop a topic outline to direct your writing. Here, you will learn what a first draft looks like, which will help you make the creative leap from the outline to the first draft. A first draft should include the following elements:
-
Introduction
- Piques the audience’s interest, conveys what the paper is about (i.e., the main idea), and motivates readers to keep reading.
- Provides the thesis statement, if one is applicable or required, to present the controlling idea of the entire piece of writing.
-
Body
- Includes several paragraphs with a topic sentence in each paragraph that states the main idea of the paragraph and connects the idea to the thesis statement or the main idea of the paper.
- Supporting sentences in each paragraph develop or explain the topic sentence. Depending on the type of writing (e.g., reflective, persuasive), these may be specific facts, examples, anecdotes, or other details that elaborate on the topic sentence.
-
Conclusion
- Reinforces the main idea or thesis statement and leaves the audience with a feeling of completion.
Student Tip
Index Card
You may want to note your purpose and audience on an index card that you clip to your paper (or keep next to your computer) as illustrated in Figure 7.1 . Write notes to yourself on the card – for example, what the audience might not know – so that you will remember to address those issues as you write.
Figure 7.1: Index card with purpose and audience
Activities: Check Your Understanding
The original version of this chapter contained H5P content. You may want to remove or replace this element.
The original version of this chapter contained H5P content. You may want to remove or replace this element.
Attribution statement
Content from this page was adapted with editorial changes from:
Writing for Success 1st Canadian Edition by Tara Horkoff is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted. Download for free at: opentextbc.ca/writingforsuccess/


36.3: Taste and Smell
Skills to Develop
- Explain in what way smell and taste stimuli differ from other sensory stimuli
- Identify the five primary tastes that can be distinguished by humans
- Explain in anatomical terms why a dog’s sense of smell is more acute than a human’s
Taste, also called gustation , and smell, also called olfaction , are the most interconnected senses in that both involve molecules of the stimulus entering the body and bonding to receptors. Smell lets an animal sense the presence of food or other animals—whether potential mates, predators, or prey—or other chemicals in the environment that can impact their survival. Similarly, the sense of taste allows animals to discriminate between types of foods. While the value of a sense of smell is obvious, what is the value of a sense of taste? Different tasting foods have different attributes, both helpful and harmful. For example, sweet-tasting substances tend to be highly caloric, which could be necessary for survival in lean times. Bitterness is associated with toxicity, and sourness is associated with spoiled food. Salty foods are valuable in maintaining homeostasis by helping the body retain water and by providing ions necessary for cells to function.
Tastes and Odors
Both taste and odor stimuli are molecules taken in from the environment. The primary tastes detected by humans are sweet, sour, bitter, salty and umami. The first four tastes need little explanation. The identification of umami as a fundamental taste occurred fairly recently—it was identified in 1908 by Japanese scientist Kikunae Ikeda while he worked with seaweed broth, but it was not widely accepted as a taste that could be physiologically distinguished until many years later. The taste of umami, also known as savoriness, is attributable to the taste of the amino acid L-glutamate. In fact, monosodium glutamate, or MSG, is often used in cooking to enhance the savory taste of certain foods. What is the adaptive value of being able to distinguish umami? Savory substances tend to be high in protein.
All odors that we perceive are molecules in the air we breathe. If a substance does not release molecules into the air from its surface, it has no smell. And if a human or other animal does not have a receptor that recognizes a specific molecule, then that molecule has no smell. Humans have about 350 olfactory receptor subtypes that work in various combinations to allow us to sense about 10,000 different odors. Compare that to mice, for example, which have about 1,300 olfactory receptor types, and therefore probably sense more odors. Both odors and tastes involve molecules that stimulate specific chemoreceptors. Although humans commonly distinguish taste as one sense and smell as another, they work together to create the perception of flavor. A person’s perception of flavor is reduced if he or she has congested nasal passages.
Reception and Transduction
Odorants (odor molecules) enter the nose and dissolve in the olfactory epithelium, the mucosa at the back of the nasal cavity (as illustrated in Figure \(\PageIndex{1}\)). The olfactory epithelium is a collection of specialized olfactory receptors in the back of the nasal cavity that spans an area about 5 cm 2 in humans. Recall that sensory cells are neurons. An olfactory receptor , which is a dendrite of a specialized neuron, responds when it binds certain molecules inhaled from the environment by sending impulses directly to the olfactory bulb of the brain. Humans have about 12 million olfactory receptors, distributed among hundreds of different receptor types that respond to different odors. Twelve million seems like a large number of receptors, but compare that to other animals: rabbits have about 100 million, most dogs have about 1 billion, and bloodhounds—dogs selectively bred for their sense of smell—have about 4 billion. The overall size of the olfactory epithelium also differs between species, with that of bloodhounds, for example, being many times larger than that of humans.
Olfactory neurons are bipolar neurons (neurons with two processes from the cell body). Each neuron has a single dendrite buried in the olfactory epithelium, and extending from this dendrite are 5 to 20 receptor-laden, hair-like cilia that trap odorant molecules. The sensory receptors on the cilia are proteins, and it is the variations in their amino acid chains that make the receptors sensitive to different odorants. Each olfactory sensory neuron has only one type of receptor on its cilia, and the receptors are specialized to detect specific odorants, so the bipolar neurons themselves are specialized. When an odorant binds with a receptor that recognizes it, the sensory neuron associated with the receptor is stimulated. Olfactory stimulation is the only sensory information that directly reaches the cerebral cortex, whereas other sensations are relayed through the thalamus.
Evolution Connection: Pheromones
A pheromone is a chemical released by an animal that affects the behavior or physiology of animals of the same species. Pheromonal signals can have profound effects on animals that inhale them, but pheromones apparently are not consciously perceived in the same way as other odors. There are several different types of pheromones, which are released in urine or as glandular secretions. Certain pheromones are attractants to potential mates, others are repellants to potential competitors of the same sex, and still others play roles in mother-infant attachment. Some pheromones can also influence the timing of puberty, modify reproductive cycles, and even prevent embryonic implantation. While the roles of pheromones in many nonhuman species are important, pheromones have become less important in human behavior over evolutionary time compared to their importance to organisms with more limited behavioral repertoires.
The vomeronasal organ (VNO, or Jacobson’s organ) is a tubular, fluid-filled, olfactory organ present in many vertebrate animals that sits adjacent to the nasal cavity. It is very sensitive to pheromones and is connected to the nasal cavity by a duct. When molecules dissolve in the mucosa of the nasal cavity, they then enter the VNO where the pheromone molecules among them bind with specialized pheromone receptors. Upon exposure to pheromones from their own species or others, many animals, including cats, may display the flehmen response (Figure \(\PageIndex{2}\)), a curling of the upper lip that helps pheromone molecules enter the VNO.
Pheromonal signals are sent, not to the main olfactory bulb, but to a different neural structure that projects directly to the amygdala (recall that the amygdala is a brain center important in emotional reactions, such as fear). The pheromonal signal then continues to areas of the hypothalamus that are key to reproductive physiology and behavior. While some scientists assert that the VNO is apparently functionally vestigial in humans, even though there is a similar structure located near human nasal cavities, others are researching it as a possible functional system that may, for example, contribute to synchronization of menstrual cycles in women living in close proximity.
Taste
Detecting a taste (gustation) is fairly similar to detecting an odor (olfaction), given that both taste and smell rely on chemical receptors being stimulated by certain molecules. The primary organ of taste is the taste bud. A taste bud is a cluster of gustatory receptors (taste cells) that are located within the bumps on the tongue called papillae (singular: papilla) (illustrated in Figure \(\PageIndex{3}\)). There are several structurally distinct papillae. Filiform papillae, which are located across the tongue, are tactile, providing friction that helps the tongue move substances, and contain no taste cells. In contrast, fungiform papillae, which are located mainly on the anterior two-thirds of the tongue, each contain one to eight taste buds and also have receptors for pressure and temperature. The large circumvallate papillae contain up to 100 taste buds and form a V near the posterior margin of the tongue.
In addition to those two types of chemically and mechanically sensitive papillae are foliate papillae—leaf-like papillae located in parallel folds along the edges and toward the back of the tongue, as seen in the micrograph. Foliate papillae contain about 1,300 taste buds within their folds. Finally, there are circumvallate papillae, which are wall-like papillae in the shape of an inverted “V” at the back of the tongue. Each of these papillae is surrounded by a groove and contains about 250 taste buds.
Each taste bud’s taste cells are replaced every 10 to 14 days. These are elongated cells with hair-like processes called microvilli at the tips that extend into the taste bud pore (illustrated in Figure \(\PageIndex{4}\)). Food molecules ( tastants ) are dissolved in saliva, and they bind with and stimulate the receptors on the microvilli. The receptors for tastants are located across the outer portion and front of the tongue, outside of the middle area where the filiform papillae are most prominent.
In humans, there are five primary tastes, and each taste has only one corresponding type of receptor. Thus, like olfaction, each receptor is specific to its stimulus (tastant). Transduction of the five tastes happens through different mechanisms that reflect the molecular composition of the tastant. A salty tastant (containing NaCl) provides the sodium ions (Na + ) that enter the taste neurons and excite them directly. Sour tastants are acids and belong to the thermoreceptor protein family. Binding of an acid or other sour-tasting molecule triggers a change in the ion channel and these increase hydrogen ion (H + ) concentrations in the taste neurons, thus depolarizing them. Sweet, bitter, and umami tastants require a G-protein coupled receptor. These tastants bind to their respective receptors, thereby exciting the specialized neurons associated with them.
Both tasting abilities and sense of smell change with age. In humans, the senses decline dramatically by age 50 and continue to decline. A child may find a food to be too spicy, whereas an elderly person may find the same food to be bland and unappetizing.
Link to Learning
View this animation that shows how the sense of taste works.
Smell and Taste in the Brain
Olfactory neurons project from the olfactory epithelium to the olfactory bulb as thin, unmyelinated axons. The olfactory bulb is composed of neural clusters called glomeruli , and each glomerulus receives signals from one type of olfactory receptor, so each glomerulus is specific to one odorant. From glomeruli, olfactory signals travel directly to the olfactory cortex and then to the frontal cortex and the thalamus. Recall that this is a different path from most other sensory information, which is sent directly to the thalamus before ending up in the cortex. Olfactory signals also travel directly to the amygdala, thereafter reaching the hypothalamus, thalamus, and frontal cortex. The last structure that olfactory signals directly travel to is a cortical center in the temporal lobe structure important in spatial, autobiographical, declarative, and episodic memories. Olfaction is finally processed by areas of the brain that deal with memory, emotions, reproduction, and thought.
Taste neurons project from taste cells in the tongue, esophagus, and palate to the medulla, in the brainstem. From the medulla, taste signals travel to the thalamus and then to the primary gustatory cortex. Information from different regions of the tongue is segregated in the medulla, thalamus, and cortex.
Summary
There are five primary tastes in humans: sweet, sour, bitter, salty, and umami. Each taste has its own receptor type that responds only to that taste. Tastants enter the body and are dissolved in saliva. Taste cells are located within taste buds, which are found on three of the four types of papillae in the mouth.
Regarding olfaction, there are many thousands of odorants, but humans detect only about 10,000. Like taste receptors, olfactory receptors are each responsive to only one odorant. Odorants dissolve in nasal mucosa, where they excite their corresponding olfactory sensory cells. When these cells detect an odorant, they send their signals to the main olfactory bulb and then to other locations in the brain, including the olfactory cortex.
Glossary
- bipolar neuron
- neuron with two processes from the cell body, typically in opposite directions
- glomerulus
- in the olfactory bulb, one of the two neural clusters that receives signals from one type of olfactory receptor
- gustation
- sense of taste
- odorant
- airborne molecule that stimulates an olfactory receptor
- olfaction
- sense of smell
- olfactory bulb
- neural structure in the vertebrate brain that receives signals from olfactory receptors
- olfactory epithelium
- specialized tissue in the nasal cavity where olfactory receptors are located
- olfactory receptor
- dendrite of a specialized neuron
- papilla
- one of the small bump-like projections from the tongue
- pheromone
- substance released by an animal that can affect the physiology or behavior of other animals
- tastant
- food molecule that stimulates gustatory receptors
- taste bud
- clusters of taste cells
- umami
- one of the five basic tastes, which is described as “savory” and which may be largely the taste of L-glutamate


8.5: Sanitation and Personal Hygiene
-
- Last updated
- Save as PDF
- BC Cook Articulation Committee
- BCcampus
Maintaining a clean work environment is critical in preventing foodborne illness. Bacteria can grow on unsanitary surfaces and then contaminate food. Just because a work surface looks clean does not mean that it is sanitary. Always ensure that you clean and sanitize a work area before starting to prepare food.
Cleaning Procedures and Schedules
Cleaning with soap and other detergents is just one step of the cleaning procedure. It is also necessary to sanitize. Cleaning will remove any dirt or grease, but will not necessarily kill any bacteria or other pathogens.
Developing a cleaning plan can help prevent the spread of foodborne pathogens and prevent an outbeak. Cleaning surfaces regulary will ensure a safe cooking environment. It is important to remember that just because it looks clean does not mean that it is free of harmful bacteria that could cause illness. Sanitizing of counter tops and cooking utensils is an important step in the cleaning process.
Routine Equipment Maintenance
All equipment must be routinely cleaned and inspected. Older equipment may have nooks and crannies where dirt and bacteria can hide, which can be difficult to clean effectively. Proper cleaning procedures must be established and followed at all times with regular review to ensure that procedures are working. If equipment is replaced or cleaning materials change, the process may have to be adjusted. Regular cleaning of equipment is also a good time to assess the equipment for any damage or wear and tear such as frayed cords, missing pieces, or broken parts. Keeping equipment clean and safe to use will prevent both illness and injury.
Importance of Personal Hygiene
It is imperative for safe food-handling outcomes for all workers to be familiar with standard sanitation and hygiene practices. Figure 6 shows the cycles of transmission of micro-organisms. One of the basic principles is to break the cycle by avoiding cross-contamination, which can be achieved by ensuring personal hygiene practices are followed.
Proper personal hygiene is critical in any food service premise. Personal hygiene includes:
- Showering and bathing regularly
- Keeping hair clean and covered or tied back
- Keeping clean clothing and footwear that is used only at work
- Handwashing regularly
- Using clean utensils for tasting food
- Using separate cloths for cleaning and wiping plates
Handwashing
Proper and regular handwashing is a critical part of any food safety system. You must always wash your hands after:
- Sneezing, coughing, or touching your mouth or nose
- Using the bathroom
- Smoking or using toothpicks
- Handling raw foods
- Cleaning and wiping tables, food preparation surfaces, or equipment
- Handling soiled objects, garbage, or money
The steps for proper handwashing are as follows:
- Wet hands with clean, running water and apply soap.
- Lather your hands by rubbing them together with soap.
- Scrub your hands for at least 20 seconds.
- Rinse hands under running water.
- Dry hands using clean towel or air drying them.
Use of Hand Sanitizers
Alcohol based hand sanitizers may be used in certain circumstances and can play a role in proper hand hygiene and reduce the spread of disease. Please view the following CDC link for more information:


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homeostasis
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maintenance of equilibrium and stability necessary for human life
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nervous system
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system that includes the brain and spinal cord (the central nervous system) and an intricate network of nerves (the peripheral nervous system)
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neurons
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the basic units of the nervous system
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neurotransmission
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the transmission of electrochemical information between neurons
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neurotransmitter
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a chemical messenger that results in action, inaction, or inhibition of a neuron
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parasympathomimetic
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drugs that stimulate or mimic the parasympathetic nervous system (rest and digest)
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sympathomimetics
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drugs that stimulate or mimic the sympathetic nervous system (fight or flight)
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synapse
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the space between two neurons