3.15: Using the Active Voice
- Use active voice effectively
Use Active Voice
Just as we want to use active verbs in writing, it is also best to write in the active voice. The active voice emphasizes the person/thing doing the action in a sentence. For example, The outfielder throws the ball . The subject, “outfielder” actively performs the action of the verb “throw.” The passive voice emphasizes the recipient of the action. In other words, something is being done to something by somebody: The ball was thrown (by the outfielder). While the passive voice has a place, particularly in some subjects like the sciences and social sciences, its overuse can result in writing that is wordy, vague, and stuffy. When possible, use the active voice to convey who or what performs the action of the verb.
Active and Passive Voices
In the simplest terms, an active voice sentence is written in the form of “A does B.” (For example, “Carmen sings the song.”) A passive voice sentence is written in the form of “B is done by A.” (For example, “The song is sung by Carmen.”) Both constructions are grammatically correct, but active voice is a more powerful kind of sentence construction for most kinds of writing. Let’s look at a couple more examples of the passive voice:
- I have been hit!
- The car when it was struck from behind.
You may have noticed something unique about the previous two sentences: the subject of the sentence is not the person (or thing) performing the action. The passive voice “hides” who does the action. Despite these sentences being completely grammatically sound, we don’t know who hit “me” or what struck the car. If these sentences used an active voice, they could read:
- The paintball hit me in the arm!
- The aggressive truck hit the car from behind.
Let’s look at a few more examples.
- Passive: Changes in gun laws were made as a result of student protests in Florida.
- Active: The Parkland student protests created changes in Florida gun laws.
- Passive: Studying can improve your grades.
- Active: Students who study hard typically earn strong grades.
Let’s look at a few more examples.
Amy grabbed the zombie survival guide.
The zombie survival guide was grabbed by Amy.
Can you see how these sentences are different?
In the first sentence, the verb grabbed is active because its subject, Amy is the doer or agent. Amy did the grabbing.
In the second sentence, was grabbed is passive because it describes an action done to its subject, guide . The doer of the action, Amy, is now the object of the preposition by . Amy comes last here, almost as if she is an afterthought instead of the important doer of the grabbing or agent of the action.
We want to use active verbs whenever possible as they allow us to express ourselves clearly, succinctly, and strongly. Active verbs imply that we’re confident with what we’re saying; we believe in our words. Looking back at the two sentences, we can see that the first one uses fewer words and offers no ambiguity about who did the action. The latter sentence is wordy and does not directly address Amy.
Are the following sentences in the active or passive voice? How can you tell?
- The samples were prepared in a clean room before being sent out for further examination.
- Karen was dancing with Joshua when she suddenly realized she needed to leave.
- Carlos was a very serious scientist with unique interests.
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- This sentence uses the passive voice. The action ( prepared ) was done to the subject of the sentence ( samples ). If this sentence were written in the active it would be something like this: “[Actor] prepared the samples in a clean room before sending them out for further examination.” Since we do not know who prepared the samples, the active sentence is incomplete.
- This sentence uses the active voice. In this case was indicates that the sentence happened in the past; it does not indicate the passive voice.
- This sentence uses the active voice. In this case was is acting as a linking verb. It links Carlos with the phrase very serious scientist .
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Revise Weak Passive-Voice Sentences
As we’ve mentioned, the passive voice can be a shifty operator—it can cover up its source, that is, who’s doing the acting, as this example shows:
-
Passive: The taxes will be collected according to the local rules and regulations.
- Collected by whom though?
- Active: The town will collect the taxes according to the local rules and regulations.
It’s this ability to cover the actor or agent of the sentence that makes the passive voice a favorite of people in authority, such as politicians, who want to obscure their agency (as if the town wasn’t responsible for collecting the taxes). At any rate, you can see how the passive voice can cause wordiness, indirectness, and comprehension problems.
Note that passive voice is sometimes appropriate to use, particularly in the sciences when the doer of the task is unimportant. For example, in a science lab, the passive voice makes sense when writing:
- Photomicrographs were taken to facilitate easy comparison of the samples.
Don’t get the idea that the passive voice is always wrong and should never be used. It is a good writing technique when we don’t want to be bothered with an obvious or too-often-repeated subject and when we need to rearrange words in a sentence for emphasis. For most of your academic writing, however, your instructors will recommend the active voice.
| Passive | Question | Active |
|---|---|---|
| Your figures have been reanalyzed in order to determine the coefficient of error. The results will be announced when the situation is judged appropriate. | Who analyzes, and who will announce? | We have reanalyzed your figures in order to determine the range of error. We will announce the results when the time is right. |
| With the price of housing at such inflated levels, those loans cannot be paid off in any shorter period of time. | Who can’t pay the loans off? | With the price of housing at such inflated levels, homeowners cannot pay off those loans in any shorter period of time. |
| After the arm of the hand-held stapler is pushed down, the blade from the magazine is raised by the top-leaf spring, and the magazine and base. | Who pushes it down, and who or what raises it? | After you push down on the arm of the hand-held stapler, the top-leaf spring raises the blade from the magazine, and the magazine and base move apart. |
| However, market share is being lost by 5.25-inch diskettes as is shown in the graph in Figure 2. | Who or what is losing market share, who or what shows it? | However, 5.25-inch diskettes are losing market share as the graph in Figure 2 shows. |
| For many years, federal regulations concerning the use of wire-tapping have been ignored . Only recently have tighter restrictions been imposed on the circumstances that warrant it. | Who has ignored the regulations, and who is now imposing them? | For many years, government officials have ignored federal regulations concerning the use of wire-tapping. Only recently has the federal government imposed tighter restrictions on the circumstances that warrant it. |
Convert these passive voice sentences into the active voice. Why is the active voice a better choice for each of these sentences?
- The process, which was essential for the experiment’s success, was completed by Enzo.
- The cake that I worked on all day long is being eaten by Justin.
- After the pattern has been applied to the fabric, work on the embroidery can be started.
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Enzo completed the process, which was essential for the experiment’s success.
- In the passive sentence, the which -clause makes the subject of the sentence excessively long. By converting the sentence to the active voice, the clause is moved to the predicate, which makes the sentence easier to understand.
-
Justin is eating the cake that I worked on all day long.
- The active voice works better in this sentence for the same reasons as sentence one. It is also likely that you would want to put emphasis on Justin in this sentence. After all, he’s doing something that is (most likely) inconsiderate.
-
After you apply the pattern to the fabric, you can start working on the embroidery.
- This sentence is likely found in a set of instructions, which are usually written directly to the reader. Addressing “you” and avoiding the passive voice will make the instructions feel more natural and accessible.
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Contributors and Attributions
- Revision and Adaptation. Provided by : Lumen Learning. License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
- Practice Activities. Provided by : Lumen Learning. Located at : courses.lumenlearning.com/styleguide/chapter/practice-activities-active-and-passive-voice/. Project : Guide to Writing. License : CC BY: Attribution
- Modification, adaptation, and original content. Authored by : Audrey Fisch for Lumen Learning. Provided by : Lumen Learning. License : CC BY: Attribution
- The Passive versus Active Voice Dilemma. Authored by : Joe Schall. Provided by : The Pennsylvania State University. Located at : https://www.e-education.psu.edu/styleforstudents/c1_p11.html . License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
- Power-Revision Techniques: Sentence-Level Revision. Authored by : David McMurrey. Located at : https://www.prismnet.com/~hcexres/textbook/hirev2.html#passive . License : CC BY: Attribution
- Active Versus Passive Verbs. Authored by : Excelsior OWL. Located at : https://owl.excelsior.edu/grammar-essentials/parts-of-speech/verbs/active-versus-passive-verbs/ . License : CC BY: Attribution
- Image of cartoon bug. Authored by : Clker-Free-Vector-Images. Provided by : Pixabay. Located at : pixabay.com/vectors/head-paper-reading-bug-insect-46204/. License : Other . License Terms : pixabay.com/service/terms/#license
- Communicating with Precision. Authored by : Suzan Last. Located at : https://pressbooks.bccampus.ca/technicalwriting/chapter/communicatingprecision/#fig2.2.1 . Project : Technical Writing Essentials. License : CC BY: Attribution


9.7: Conductors and Applications of Electrostatics
Learning Objectives
- List the three properties of a conductor in electrostatic equilibrium.
- Explain why the electric field is zero inside a conductor in electrostatic equilibrium.
- Describe how a lightning rod works.
- Name several real-world applications of the study of electrostatics.
Conductors contain free charges that move easily. When excess charge is placed on a conductor or the conductor is put into a static electric field, charges in the conductor quickly respond to reach a steady state called electrostatic equilibrium .
Figure \(\PageIndex{1}\) shows the effect of an electric field on free charges in a conductor. The free charges move until the field is perpendicular to the conductor’s surface. There can be no component of the field parallel to the surface in electrostatic equilibrium, since, if there were, it would produce further movement of charge.
A conductor placed in an electric field will be polarized . Figure \(\PageIndex{2}\) shows the result of placing a neutral conductor in an originally uniform electric field. The field becomes stronger near the conductor but entirely disappears inside it.
MISCONCEPTION ALERT: ELECTRIC FIELD INSIDE A CONDUCTOR
Excess charges placed on a spherical conductor repel and move until they are evenly distributed, as shown in Figure \(\PageIndex{3}\). Excess charge is forced to the surface until the field inside the conductor is zero. Outside the conductor, the field is exactly the same as if the conductor were replaced by a point charge at its center equal to the excess charge.
PROPERTIES OF A CONDUCTOR IN ELECTROSTATIC EQUILIBRIUM
- The electric field is zero inside a conductor.
- Just outside a conductor, the electric field lines are perpendicular to its surface, ending or beginning on charges on the surface.
- Any excess charge resides entirely on the surface or surfaces of a conductor.
The properties of a conductor are consistent with the situations already discussed and can be used to analyze any conductor in electrostatic equilibrium. This can lead to some interesting new insights, such as described below.
How can a very uniform electric field be created? Consider a system of two metal plates with opposite charges on them, as shown in Figure \(\PageIndex{4}\). The properties of conductors in electrostatic equilibrium indicate that the electric field between the plates will be uniform in strength and direction. Except near the edges (which can be ignored when plates are close to each other), the excess charges distribute themselves uniformly, producing field lines that are uniformly spaced (hence uniform in strength) and perpendicular to the surfaces (hence uniform in direction, since the plates are flat).
In fact, this is a particular example of electric circuit elements called capacitors . This particular example is called a parallel-plate capacitor and can be used to analyze properties of capacitors in general, such as how many charges can be stored using two nearby conductors set at a certain electric potential difference (voltage) apart. Capacitors find wide use in electric circuits alongside the resistors and inductors that you will learn about later.
Electric Fields on Uneven Surfaces
So far we have considered excess charges on a smooth, symmetrical conductor surface. What happens if a conductor has sharp corners or is pointed? Excess charges on a nonuniform conductor become concentrated at the sharpest points. Additionally, excess charge may move on or off the conductor at the sharpest points. To see how and why this happens, consider the charged conductor in Figure \(\PageIndex{5}\). The electrostatic repulsion of like charges is most effective in moving them apart on the flattest surface, and so they become least concentrated there. The same effect is produced on a conductor by an externally applied electric field, as seen in Figure \(\PageIndex{5}\)(c). Since the field lines must be perpendicular to the surface, more of them are concentrated on the most curved parts.
Applications of Conductors
On a very sharply curved surface, such as shown in Figure \(\PageIndex{6}\), the charges are so concentrated at the point that the resulting electric field can be great enough to remove them from the surface. This can be useful.
Lightning rods work best when they are most pointed. The large charges created in storm clouds induce an opposite charge on a building that can result in a lightning bolt hitting the building. The induced charge is bled away continually by a lightning rod, preventing the more dramatic lightning strike.
Of course, we sometimes wish to prevent the transfer of charge rather than to facilitate it. In that case, the conductor should be very smooth and have as large a radius of curvature as possible (see Figure \(\PageIndex{7}\), which shows a Van de Graaff generator). Smooth surfaces are used on high-voltage transmission lines, for example, to avoid leakage of charge into the air.
Another device that makes use of some of these principles is a Faraday cage . This is a metal shield that encloses a volume. All electrical charges will reside on the outside surface of this shield, and there will be no electrical field inside. A Faraday cage is used to prohibit stray electrical fields in the environment from interfering with sensitive measurements, such as the electrical signals inside a nerve cell.
During electrical storms if you are driving a car, it is best to stay inside the car as its metal body acts as a Faraday cage with zero electrical field inside. If in the vicinity of a lightning strike, its effect is felt on the outside of the car and the inside is unaffected, provided you remain totally inside. This is also true if an active (“hot”) electrical wire was broken (in a storm or an accident) and fell on your car.
Below are additional applications of electrostatics , the study of electricity in electrostatic equilibrium, many of them using conductors for their properties just discussed above.
The Van de Graaff Generator
Van de Graaff generators (or Van de Graaffs) are not only spectacular devices used to demonstrate high voltage due to static electricity—they are also used for serious research. The first was built by Robert Van de Graaff in 1931 (based on original suggestions by Lord Kelvin) for use in nuclear physics research. Figure \(\PageIndex{8}\) shows a schematic of a large research version. Van de Graaffs utilize both smooth and pointed surfaces, and conductors and insulators to generate large static charges and, hence, large voltages.
A very large excess charge can be deposited on the sphere, because it moves quickly to the outer surface. Practical limits arise because the large electric fields polarize and eventually ionize surrounding materials, creating free charges that neutralize excess charge or allow it to escape. Nevertheless, voltages of 15 million volts are well within practical limits.
TAKE-HOME EXPERIMENT: ELECTROSTATICS AND HUMIDITY
Rub a comb through your hair and use it to lift pieces of paper. It may help to tear the pieces of paper rather than cut them neatly. Repeat the exercise in your bathroom after you have had a long shower and the air in the bathroom is moist. Is it easier to get electrostatic effects in dry or moist air? Why would torn paper be more attractive to the comb than cut paper? Explain your observations.
Xerography
Most copy machines use an electrostatic process called xerography —a word coined from the Greek words xeros for dry and graphos for writing. The heart of the process is shown in simplified form in Figure \(\PageIndex{9}\).
A selenium-coated aluminum drum is sprayed with positive charge from points on a device called a corotron. Selenium is a substance with an interesting property—it is a photoconductor . That is, selenium is an insulator when in the dark and a conductor when exposed to light.
In the first stage of the xerography process, the conducting aluminum drum is grounded so that a negative charge is induced under the thin layer of uniformly positively charged selenium. In the second stage, the surface of the drum is exposed to the image of whatever is to be copied. Where the image is light, the selenium becomes conducting, and the positive charge is neutralized. In dark areas, the positive charge remains, and so the image has been transferred to the drum.
The third stage takes a dry black powder, called toner, and sprays it with a negative charge so that it will be attracted to the positive regions of the drum. Next, a blank piece of paper is given a greater positive charge than on the drum so that it will pull the toner from the drum. Finally, the paper and electrostatically held toner are passed through heated pressure rollers, which melt and permanently adhere the toner within the fibers of the paper.
Laser Printers
Laser printers use the xerographic process to make high-quality images on paper, employing a laser to produce an image on the photoconducting drum as shown in Figure \(\PageIndex{10}\). In its most common application, the laser printer receives output from a computer, and it can achieve high-quality output because of the precision with which laser light can be controlled. Many laser printers do significant information processing, such as making sophisticated letters or fonts, and may contain a computer more powerful than the one giving them the raw data to be printed.
Ink Jet Printers and Electrostatic Painting
The ink jet printer , commonly used to print computer-generated text and graphics, also employs electrostatics. A nozzle makes a fine spray of tiny ink droplets, which are then given an electrostatic charge. (See Figure \(\PageIndex{11}\).)
Once charged, the droplets can be directed, using pairs of charged plates, with great precision to form letters and images on paper. Ink jet printers can produce color images by using a black jet and three other jets with primary colors, usually cyan, magenta, and yellow, much as a color television produces color. (This is more difficult with xerography, requiring multiple drums and toners.)
Electrostatic painting employs electrostatic charge to spray paint onto odd-shaped surfaces. Mutual repulsion of like charges causes the paint to fly away from its source. Surface tension forms drops, which are then attracted by unlike charges to the surface to be painted. Electrostatic painting can reach those hard-to-get at places, applying an even coat in a controlled manner. If the object is a conductor, the electric field is perpendicular to the surface, tending to bring the drops in perpendicularly. Corners and points on conductors will receive extra paint. Felt can similarly be applied.
Smoke Precipitators and Electrostatic Air Cleaning
Another important application of electrostatics is found in air cleaners, both large and small. The electrostatic part of the process places excess (usually positive) charge on smoke, dust, pollen, and other particles in the air and then passes the air through an oppositely charged grid that attracts and retains the charged particles. (See Figure \(\PageIndex{12}\).)
Large electrostatic precipitators are used industrially to remove over 99% of the particles from stack gas emissions associated with the burning of coal and oil. Home precipitators, often in conjunction with the home heating and air conditioning system, are very effective in removing polluting particles, irritants, and allergens.
Section Summary
- The electrical forces around a conductor will cause free charges to move around inside the conductor until static equilibrium is reached.
- Any excess charge will collect along the surface of a conductor.
- Conductors with sharp corners or points will collect more charge at those points.
- A lightning rod is a conductor with sharply pointed ends that collect excess charge on the building caused by an electrical storm and allow it to dissipate back into the air.

- In addition to research using equipment such as a Van de Graaff generator, many practical applications of electrostatics exist, including photocopiers, laser printers, ink-jet printers and electrostatic air filters.
Glossary
- conductor
- an object with properties that allow charges to move about freely within it
- free charge
- an electrical charge (either positive or negative) which can move about separately from its base molecule
- electrostatic equilibrium
- an electrostatically balanced state in which all free electrical charges have stopped moving about
- polarized
- a state in which the positive and negative charges within an object have collected in separate locations
- Faraday cage
- a metal shield which prevents electric charge from penetrating its surface
- capacitor
- an arrangement of conductors designed to store charge using voltage difference
- parallel-plate capacitor
- an example of capacitor using arrangement of two parallel conducting plates placed near each other
- Van de Graaff generator
- a machine that produces a large amount of excess charge, used for experiments with high voltage
- electrostatics
- the study of electricity in electrostatic equilibrium
- photoconductor
- a substance that is an insulator until it is exposed to light, when it becomes a conductor
- xerography
- a dry copying process based on electrostatics
- grounded
- connected to the ground with a conductor, so that charge flows freely to and from the Earth to the grounded object
- laser printer
- uses a laser to create a photoconductive image on a drum, which attracts dry ink particles that are then rolled onto a sheet of paper to print a high-quality copy of the image
- ink-jet printer
- small ink droplets sprayed with an electric charge are controlled by electrostatic plates to create images on paper
- electrostatic precipitators
- filters that apply charges to particles in the air, then attract those charges to a filter, removing them from the airstream


6.7: Waiting a While
Waiting a While for the Payoff: Insitutec
High-tech bootstrapping
Imagine trying to bootstrap a company that makes industrial positioning and measuring systems with nanoscale resolution. Sound tough? It’s exactly what Shane and Bethany Woody, co-founders of Charlotte-based InsituTec, Inc., have been doing since incorporating in 2001.
Shane, a University of North Carolina at Charlotte mechanical engineering PhD candidate, first started working on industrial measuring systems to meet a need articulated by Boeing. Shane studies and works at the Center for Precision Metrology at UNCC, which brings in corporations that have specific needs they want addressed by university researchers. Boeing’s military and commercial aircraft have millions of small rivet holes; at the time they contacted Shane they measured the holes by transferring samples to a metrology laboratory: a slow, expensive, and time-consuming process. Boeing needed a faster, cheaper way to measure the size and form of the holes in real time. Shane met the challenge, designing a prototype of a vector-based probe that would allow the measuring to take place within the manufacturing process itself, with comparable accuracy and at a lower cost. Timing was bad, however, as the economy went on a downswing—Boeing pulled out.
But the technology was too promising to leave behind. In 2001 Shane won Advanced E-Team funding from the NCIIA to optimize the probe and move toward commercialization, and the team officially incorporated as InsituTec, Inc. Bootstrapping began.
How have they done it? According to Shane, the most important factor in InsituTec’s high-tech bootstrapping success has been their incubator. The Office of Technology Transfer at UNCC provides high-tech startups with office space and access to laboratory equipment based on a fixed-fee agreement in which they pay based on what facilities and office space they use. Since both Bethany and Shane are graduate students they receive free office space; they’re charged only for InsituTec-related use of university equipment. And that equipment is extremely expensive.
“One of the instruments we use to test our devices costs about sixty to eighty thousand dollars,” says Shane. “That’s why without the incubator InsituTec wouldn’t really be possible.”
“If it wasn’t for the university incubator program we would have no hope of even having this company right now,” adds Bethany. “That we pay for the equipment on an hourly basis instead of having to buy it is absolutely invaluable.”
The second major factor in their bootstrapping success is salary. That is, the big salaries they don’t pay themselves. Shane pays himself far less than what the typical engineering graduate makes. “I make a tiny fraction of what I could be paying myself,” he says. “But we just have to do that right now.”
Bethany works for no pay. She has a second job that pays the bills and offers her services to InsituTec at no cost. “My time is free to the company,” she says.  We’re in this to build the company and be successful, so a little sacrifice now for success later is worth it to us.”
Another source of savings comes in the form of materials used in making the devices themselves. Says Bethany, “We spend every penny wisely. When we put together systems and devices we pinch every penny and do it cheaper and leaner than bigger companies. We watch everything we order. We look for the best deals. If we can get something two dollars cheaper elsewhere, we take it.”
If all goes well, they’ll be out of bootstrapping mode in a year. “Four months ago we received a Phase I SBIR grant,” says Shane. “We’re writing several proposals for other grants. We’re working on a development contract with a large industrial equipment company. We’re getting there.”
In the meantime Bethany offers some advice to young student inventors who may be facing years of tough bootstrapping: “If you have a company and you have a stake in it you should be willing to sacrifice early on. Don’t expect to pay yourself top dollar and succeed. If everything works out, you’ll get a big payoff later.”


11.4: Soil Profiles
Soil formation begins first with the break down of rock into regolith. Continued weathering and soil horizon development process leads to the development of a soil profile , the vertical display of soil horizons. Watch the typical progression of a soil profile then read the description below of a generic, fully developed soil.
O Horizon
At the top of the profile is the O horizon. The O horizon is primarily composed of organic matter. Fresh litter is found at the surface, while at depth all signs of vegetation structure has been destroyed by decomposition. The decomposed organic matter, or humus, enriches the soil with nutrients (nitrogen, potassium, etc.), aids soil structure (acts to bind particles), and enhances soil moisture retention.
A Horizon
Beneath the O horizon is the A horizon. The A horizon marks the beginning of the true mineral soil. In this horizon organic material mixes with inorganic products of weathering. The A horizon typically is dark colored horizon due to the presence organic matter. Eluviation , the removal of inorganic and organic substances from a horizon by leaching occurs in the A horizon. Eluviation is driven by the downward movement of soil water.
E Horizon
The E horizon generally is a light-colored horizon with eluviation being the dominant process. Leaching, or the removal of clay particles, organic matter, and/or oxides of iron and aluminum is active in this horizon. Under coniferous forests, the E horizon often has a high concentration of quartz giving the horizon an ashy-gray appearance.
B Horizon
Beneath the E horizon lies the B horizon. The B horizon is a zone of illuviation where downward moving, especially fine material, is accumulated. The accumulation of fine material leads to the creation of a dense layer in the soil. In some soils the B horizon is enriched with calcium carbonate in the form of nodules or as a layer. This occurs when the carbonate precipitates out of downward moving soil water or from capillary action. The diagram below illustrates the effect of climate on eluviation and illuviation. Eluviation is significant in humid climates where ample precipitation exists and a surplus in the water balance occurs. Illuvial layers are found low in the soil profile. Illuvial zones are found closer to the surface in semiarid and arid climates where precipitation is scarce. Capillary action brings cations like calcium and sodium dissolved in soil water upwards where they precipitate from the water.
C Horizon
The C horizon represents the soil parent material, either created in situ or transported into its present location. Beneath the C horizon lies bedrock.
The preceding paragraphs describe a generic soil profile, yet not all soils have each one of the horizons, nor are they all the same with respect to thickness composition and structure. Newly formed "immature" soils may only have an O-A-C sequence while older more "mature" soils display the full profile of horizons as described above. The particular compositional, structural and chemical composition of the soil depends on the various factors that influence soil formation.


8.3.1: Food Preparation
When selecting foods to plan a menu and foods to offer a patient , Home Health Aides / Personal Care Aides should use the basics of good nutrition and follow the ChooseMyPlate guidelines found at www . choosemyplate . org
- Choose a variety of foods to keep it interesting.
- Choose foods that are low in fat, low in saturated fat, and low in cholesterol
- Select lean meats, fish, and poultry. Avoid fatty cuts of meats. Remove the skin from poultry to reduce fat.
- Use sugar and salt in moderation.
- Herbs and spices can be used to help flavor food and according to the patient’s preferences.
- Choose plenty of fruit, vegetable, and grain products for snacks and meals.
- Avoid frying foods as this adds extra calories, fat, and cholesterol.
- Steam vegetables to maintain the most flavor and nutrition.
- Bake, broil, or microwave foods rather than frying or sautéing in butter or oil.
- Avoid convenience foods such as those that are pre-made or prepackaged. When foods are prepared fresh, you always know the ingredients and there will be less preservatives, sodium, fat, and calories.
1. Which method of food preparation is the least healthy?
a). Broiling
b). Steaming
c). Frying
d). Roasting
2. Skin can be removed from meat and poultry to reduce fat. True or False? ________
- Answer
-
1. C
2. True
FEEDBACK :
1. Frying foods is the least healthy option as this adds extra fat, cholesterol, and calories from using oils during the frying process. Broiling, steaming, and roasting methods of cooking do not add extra calories, as long as butter, margarine, and oils are not used.
2. To decrease the amount of fat and make healthier food choices, remove skin from meat and poultry, as this is where extra fat and cholesterol are. Lean cuts of meat can also be selected to decrease fat, cholesterol, and calories.
Patient Involvement
It is very important for Home Health Aides/Personal Care Aides to involve their patient in the planning and preparing of meals. Not only is the patient more likely to eat foods if they choose them, but it also helps to promote independence and self-determination . Working with a patient to plan meals and prepare foods can also help to strengthen the relationship. Share tasks of food preparation, keeping in mind any physical or cognitive limitations a patient may have.
Home Health Aides/Personal Care Aides should not allow their patient to perform unsafe tasks if they are unable to do so. For example, young children should not be allowed to use sharp knives and dangerous equipment. A person with dementia who may forget what they are doing should be closely supervised while using knives or the stove. If adaptive equipment is available, teach and encourage the patient to use it. If they can assist to provide their own care, this will help promote self-esteem and independence.
Getting involved in meal planning and preparation can also provide mental and physical stimulation, as well as relaxation and distraction. It can be a time where patients are encouraged to be creative and draw upon their strengths and talents, especially if they enjoy cooking. Many people enjoy food, either cooking or eating it. Home Health Aides/Personal Care Aides can make this time fun and relaxing by going through cookbooks and magazines with attractive pictures to help stimulate interests in food. Make a list of items that are on hand and Home Health Aides/Personal Care Aides can even make planning a meal with on-hand ingredients a fun game.
Available Cooking Equipment
While preparing food in a patient’s home, Home Health Aides/Personal Care Aides may only have access to the available equipment they have on hand. There may not be a lot of equipment to choose from. They may need to get creative in order to adequately meet their patient’s nutritional needs. Discuss ideas with a supervisor about how to best do this.


1.1: Defining Population Health
By the end of this section, you should be able to:
- Define population health.
- Explain the origin of the population health approach.
- Identify the components of population health.
- Discuss the global application of population health.
Population health is a comprehensive approach that spans the entire health care continuum, from public health prevention to disease management. Population health aims to support the health of people through diverse activities, including care coordination , health care research, population-level data analysis , and health programming. Activities carried out to improve population health generally support the health status and health outcomes of groups of people rather than one client at a time. Population health intervention s take a more holistic approach than those that are generally used in the care of individual clients. Population health considers the impact of public policy and law as well as environmental, social, behavioral, and other factors that might facilitate or hinder health for all people. The requisite knowledge of these disciplines and health areas comes together to address many factors that can influence health.
Consider tobacco use, which, as the leading cause of preventable death in the United States, kills an estimated 1,300 Americans each day. Individual counseling and interventions such as prescription medications and nicotine gum can help individuals quit smoking. While a population health approach to addressing tobacco smoking cessation would support the availability of individual tools, it would also consider the broader factors contributing to smoking rates and smoking uptake across the population. A population health approach to smoking cessation might include the following:
- Developing community-wide antismoking campaigns
- Advocating for schools, businesses, restaurants, and other public places to develop smoke-free policies
- Researching the reasons that community members start or do not quit smoking
- Analyzing population-level data to identify trends in smoking
- Passing legislation to increase taxes on tobacco products to discourage their purchase and fund population health programs focused on cessation
Overall, a population health approach that considers the multifaceted facilitators and deterrents of smoking can help reduce smoking rates, thereby improving the health of smokers and the population at large.
Drunk driving is another example of a serious public health problem. The National Highway Traffic Safety Administration estimates that in the United States, one person is killed due to drunk driving every 39 minutes. Drunk driving impacts not only the life of the victim but also the lives of their friends, family, and community, and those of the driver as well. Individual-level interventions that work to improve the health of drivers and of community members to whom a driver may pose a risk include individual counseling, installing breathalyzer car ignition devices, and levying fines or revoking driver’s licenses to hold drivers accountable and prevent future drunk driving occurrences. Population health interventions go beyond those aimed at specific drunk drivers. A population health approach to drunk driving reduction could include the following:
- Developing and implementing stricter laws and regulations regarding alcohol use and driving
- Leading campaigns to raise awareness about the dangers and penalties of drunk driving
- Collaborating with taxi companies and ride-share programs on weekends and holidays to offer free or reduced rides
- Training servers, bartenders, and liquor store employees on the responsible service and sale of alcohol
- Identifying high-risk areas for drunk driving accidents to increase signage and safety checks in these areas
In nursing, a population is a group of people that may receive care in various settings at the local, regional, national, and global levels (American Association of Colleges of Nursing [AACN], 2021). Examples of populations include all students at a specific college campus (local), all people who live or work in Northern California (regional), all residents of the United States (national), or all children with asthma across nations (global). The health care continuum encompasses public health, acute care, ambulatory care, and long-term care to collectively address a population’s diverse health needs. The health care continuum and the role of nurses will be discussed further later in the chapter.
Population health involves collaborative efforts among health care professionals, communities, industries, academia, and governmental organizations to improve health outcomes among a population (AACN, 2021). A myriad of efforts in population health can explain or address why some populations are healthier than others and help determine how resources might be allocated to have the greatest impact on improving health across the population. As the smoking cessation and drunk driving examples illustrate, population health approaches focus on implementing education, policy, and programming that provide optimal outcomes for the money, time, and other resources invested. Nurses working in many settings—such as hospitals, schools, homes, communities, industries, and businesses—not only support but also shape population health across the United States (Ariosto et al., 2018). Nurses are critical in advocating for policies, implementing interventions, and ensuring that diversity, equity, inclusion, justice, and ethics are prioritized to achieve population health goals focused on health promotion, disease prevention, risk reduction, and emergency preparedness (AACN, 2021).
There is no definitive history of exactly when population health emerged and evolved into what health care providers, teams, and organizations know it as today (Szreter, 2003). Scholars note several defining moments from the 18th century through the modern day, such as observations of differences in health conditions between the wealthy and the impoverished, among people employed in various industries, and between those with and without access to clean water (Bynum, 1983; LaBerge, 1993; Porter, 1991). These historical moments allowed for recognition of the relationship between a healthy human population and a healthy, functioning society. Although population health concepts and principles have been relevant to professional nursing practice for centuries, in the United States the passage of the Patient Protection and Affordable Care Act (ACA) in 2010 is credited with beginning to shift the focus of health care services from treating diseases in individual people to promoting health among populations (Ariosto et al., 2018). Emphasizing preventive efforts and proactively facilitating health instead of reactively treating diseases as they occur is a central tenet of population health. The shift is essential, as many recognize that a U.S. health care system that spends an estimated 75 to 90 percent of its resources addressing diseases and hospitalizations and invests very little in preventive efforts is a system that is failing (Raghupathi & Raghupathi, 2018; Shrank et al., 2019; Centers for Disease Control and Prevention [CDC], 2023). By shifting the focus from reactive disease treatment to proactive health promotion, population health offers a more positive path forward. Under a population health–focused system, health care professionals are encouraged to work collaboratively to promote early intervention, provide health education, empower clients, and effect social change to reduce the burden of disease for individuals and the health care system at large.
The Quintuple Aim
Population health can impact numerous specific conditions, diseases, and health risks through interventions that cross disciplines and support a great breadth and depth of positive health change. As a field of study and practice, population health works toward specific aims developed by the Institute for Healthcare Improvement (IHI). In 2007, the IHI developed a framework called the Triple Aim to support optimal performance of the health care system (Berwick et al., 2008). In 2014, the IHI updated the framework to the Quadruple Aim to acknowledge that the health of providers and other health care professionals must be supported to achieve population health goals (Bodenheimer & Sinsky, 2014). Today, the four aims consist of:
- improving the client experience of care (including quality and satisfaction),
- improving the health of populations,
- reducing the per capita cost of health care, and
- improving the well-being of health care professionals.
Recently, experts have suggested a revision to create the Quintuple Aim , which would include a fifth aim of advancing health equity. In both the fourth and suggested fifth aim expansions, experts have posited that improving population health, client experience, and health cost would be impossible without addressing provider health and burnout or health equity (Bodenheimer & Sinsky, 2014; Nundy et al., 2022). Concepts of the Quintuple Aim can guide evaluations of population health programs and initiatives. For example, telemedicine connects to the goals of improving the health of populations, improving the well-being of health care professionals, and advancing health equity. Its services offer several conveniences to clients and clinicians, such as the flexibility to dial in from home and save on commuting fees. These services also remove barriers to receiving care and increase equity in opportunity for clients to see primary care providers and specialists. This can help reduce inequities and disparities with regard to receiving screenings, diagnoses, and treatments for health conditions, which in turn can help improve population health. Telehealth is a growing initiative across health care globally; please see Care Transition and Coordination Across the Community for more information on telehealth. Recently, one research team determined that pediatric telehealth has advanced pediatric care in general so that it has become a better-performing, more equitable system (Cahan et al., 2020). Whether a population, community, or health system elects to use the version with three, four, or five aims, this framework encourages consideration of the interplay among the different aims and innovative approaches to improving health and health outcomes for the population.
Components of Population Health
Population health takes a comprehensive approach that accounts for the complex dynamics among differences in health status, community resources, personal characteristics, familial circumstances, and other factors that can trigger or aggravate health conditions. By recognizing the complex interplay of these numerous and wide-ranging factors, population health takes a holistic view to promote the well-being of all.
Regardless of the situation or specific factors, a guiding theme of population health is the importance and value of taking proactive rather than reactive approaches to improving health. An analogy to summarize population health involves an overflowing sink. Imagine a kitchen faucet is left running unattended, creating a giant puddle on the floor. Better get a mop! Without population health, much of health care focuses on “mopping the floor” instead of “turning off the faucet” (Kaminski, 2021). In other words, health care as a system largely deals with floods—that is, helping clients who are already sick—instead of turning off the water, or addressing the situations and circumstances that make clients sick in the first place. Health care providers, nurses, policymakers, and the health care system at large should focus on the causes of health problems to prevent them before they occur, instead of focusing primarily on treating diseases as they happen. Of course, clients, families, and communities need access to treatment for their health conditions—but what if there was a way to prevent the conditions from happening in the first place?
Four key health concepts have been essential in advancing population health: outcomes , disparities , determinants , and risk factors .
Outcomes are all possible results. Health outcomes are indicators or data points that reflect the degree to which health interventions, care, policies, and behaviors are effective in supporting the health status of populations. Examples of health outcomes include mortality rates, life expectancy, disability rates, birth rates, health care costs, and health-related quality of life measures. Outcomes may come from exposure to interventions that aim to prevent or treat a condition, or they may result from exposure to health risks or situations detrimental to health. For example, creating a policy that allows people under a certain income level to have free health insurance may produce a range of outcomes, including insuring a greater percentage of the population and increasing the number of people who attend wellness exams—and, consequently, increasing the number of people who smoke who may be offered smoking cessation resources. On the other hand, removing or relaxing policies that prohibit smoking in public places may produce quite a different range of outcomes, including making it more difficult for people to quit smoking, exposing more people to secondhand smoke, and increasing rates of children who start smoking.
Disparities are inequalities or differences. A related concept is health inequities , which are avoidable inequalities related to health that stem from a form of injustice (Kawachi et al., 2002; McCartney et al., 2019). For example, children attending the Lincoln School may have higher rates of asthma than children attending the Washington School. The children are all the same age and have the same racial and ethnic distribution, but the parents of children at the Washington School have a higher average income and donated money so that each classroom could have an air conditioner. There is a disparity in access to clean air, as well as in rates of asthma, between children at these two schools. Health Disparities covers this topic in greater detail.
Determinants are the innumerable factors that influence health and generally include nonmedical events, characteristics, or other entities that change a health condition or the level of a health problem (Kindig, 2007; Office of Disease Prevention and Health Promotion, 2022). Within population health, determinants of interest include medical care, public health interventions, income, education, employment, social support, culture, clean air and water, outdoor space, genetics, and behavior (Kindig, 2007). Determinants can interact with each other to bolster health or worsen a problem (Figure 1.2). For example, when a client is unable to finish high school, they may not qualify for a full-time job that pays a living wage and offers access to a health insurance plan. Such a situation would undoubtedly impact the client’s ability to seek care when needed and to engage in health promotion efforts.
Social determinants of health are additional factors that influence the health of populations, families, and individuals. Social determinants of health are conditions and social factors that affect outcomes and risk related to health, functioning, and quality of life. Conditions or factors in hospitals, clinics, workplaces, homes, towns and cities, schools, and beyond influence health outcomes for the population. Economic stability, education access and quality, health care access and quality, neighborhood and built environment, and social and community context are five domains that shape the social determinants of health (Office of Disease Prevention and Health Promotion, 2022). Please see Social Determinants Affecting Health Outcomes for a comprehensive discussion of social determinants of health.
Risk factors are aspects of personal behaviors, lifestyle choices, exposures, or attributes that generally increase the likelihood of acquiring or the severity of a health condition. Risk factors are similar to determinants but tend to be more specific. Consider respiratory disease determinants and risk factors. Air quality and environmental pollution are determinants of respiratory disease, while smoking is a risk factor for respiratory disease. Some determinants may be risk factors; however, other determinants may reduce health risk.
Healthy People 2030 developed 25 measurable objectives, one developmental objective, and one research objective to address tobacco use. Since creating these objectives , three targets have been met or exceeded: reducing cigarette smoking in adolescents, reducing the use of smokeless tobacco products among adolescents, and reducing the lung cancer death rate.
Social determinants affect how environments where people live, work, and play impact health and well-being for all. This video explains different social determinants of health in depth.
Watch the video, and then respond to the following questions.
- What is the greatest risk to economic stability in the community around your nursing school?
- How does your nursing school support educational access and quality?
- Do clients in the community by your nursing school have adequate access to health care?
- Can you identify three risks and three supports in the neighborhood and built environment around your nursing school?
- In your nursing school, what experiences do you participate in that contribute to the growth of the social community and context?
Additionally, population health focuses on upstream, midstream, and downstream approaches to improve health outcomes (Figure 1.3) (Salmond & Allread, 2019).
- Upstream interventions involve enacting policies that change regulations, increase access, or provide economic incentives to impact health across a population. Examples include policy changes regarding the fast food or tobacco industry, provision of universal health care, and compensation for hospitals with lower inpatient admission rates (Porter et al., 2022).
- Midstream approaches are those that happen within specific organizations. For example, a workplace may provide healthy lunches to employees each day (Porter et al., 2022).
- Downstream interventions focus on the behavior of individual people to modify the risk of disease, prevent illness, or manage chronic conditions (Brownson et al., 2010; Fornili, 2022). For example, a nurse might counsel a client with hypertension about consuming a low-salt diet.
These key components interact in complex and evolving ways as population health and the health status of the population change over time. By employing upstream interventions, such as policy changes and universal health care, population health addresses the societal factors that impact the health of the population on a broad scale and ultimately the health of individual clients. Midstream approaches can contribute to fostering healthier environments in diverse settings. Downstream interventions, such as those that focus on individual behavior to support health, are also important in a population health model, as members of the population will never be fully free of health conditions requiring treatment. Together, upstream, midstream, and downstream approaches offer a framework for population health programming and interventions that can create positive health outcomes.
Read the scenario, and then respond to the questions that follow.
Forty-year-old Christopher Lee has hypertension. Although he has not attended a health checkup in a few years, he feels that his blood pressure might be lower since he lost his job. Being unemployed has been stressful, but as a Korean American, he experienced anti-Asian sentiment and discrimination from his coworkers during the COVID-19 pandemic. The Lees’ 5-year-old daughter, Sunshine, just started kindergarten and has an EpiPen for a life-threatening nut allergy. She attended an after-school arts and crafts program twice a week but stopped going when Christopher lost his job. The Lees’ 2-year-old son, Woody, is generally healthy and attends the day care where Alexandra works. Christopher’s parents live in South Korea and will visit the United States in a few months to help when the Lees’ new baby is born.
- Based on what you now know about the Lee family, what are some possible health challenges they may face?
- What are some possible upstream factors influencing their actual or potential health challenges? Are there any midstream and downstream factors that might support or harm their health?
Global Population Health
The need to address the factors and components of population health is a global one, and given the interconnected nature of the health status of people around the world, nurses should prioritize and actively contribute to enhancing global population health in addition to advancing local and national population health programs, goals, and outcomes. Many people around the world face significant challenges to promoting their health, receiving treatments, and reducing health risks. Health outcomes, disparities, determinants, risk factors, and upstream, midstream, and downstream influences are all relevant and crucial to improving global population health. The health status of people as far away as a different continent on other side of the equator can impact the health of clients locally, and nurses have a responsibility to support efforts that advance population health worldwide (Hong & Lee, 2021; Wilson et al., 2016). Nurses have a duty to extend their care, genuine concern, empathy, and compassion to those in need beyond their immediate surroundings. To that end, a global advisory panel on the future of nursing proposed a definition of global nursing:
Global nursing is the use of evidence-based nursing processes to promote sustainable planetary health and equity for all people. Global nursing considers social determinants of health, [and] includes individual and population-level care, research, education, leadership, advocacy, and policy initiatives. Global nurses engage in ethical practice and demonstrate respect for human dignity, human rights, and cultural diversity. Global nurses engage in a spirit of deliberation and reflection in interdependent partnership with communities and other health care providers. (Wilson et al., 2016, p. 1537)
When nurses engage in global nursing, they can proactively contribute to bettering population health and reducing the global burden of disease, health conditions, disability, and disparities. By embodying a commitment to global nursing, nurses can positively impact and improve the lives of others and uphold the principles of the discipline. Almost any health issue, concern, condition, or topic can be a global population health problem needing solutions.
Climate Health
People living in the western United States may recall having “smoke days” off from school due to poor air quality from wildfire smoke, while those from the East Coast and Midwest may recall a few days in June 2023 when the skies were tinted orange and air quality was exceptionally poor due to wildfire smoke movement from Canada. That same summer, wildfires burning out of control across Greece caused the evacuation of 19,000 people (Smith & Chrisafis, 2023). Exposure to wildfire smoke and poor air quality impacts the health of humans and animals alike. It exacerbates respiratory conditions, may cause congenital anomalies, and can even contribute to lower academic performance for students (Amjad et al., 2021; Gan et al., 2020; Wen & Burke, 2022). Wildfires are one example of an extreme weather or climate event that causes significant harm to mental health and well-being and contributes to morbidity and mortality around the globe (Ebi et al., 2021).
In addition to causing wildfires, extreme weather—in the form of high temperatures, torrential rains, and prolonged drought—puts the health of the population at risk around the world. The levels of extreme heat that were experienced across Asia, Europe, and the United States during the summer of 2023 are enough to worsen existing respiratory conditions and cause heat stroke, a life-threatening emergency (CDC, n.d.). Heavy rains and flooding can contribute to the development of climate-sensitive infections like malaria, dengue, diarrheal diseases, and emerging infections, as disease-causing pathogens are able to thrive in the unusually wet conditions (Choisy et al., 2022). Global climate scientists are particularly concerned about the effects of climate change in Asia, where temperatures have been rising two times faster than in other parts of the world (Dabla-Norris et al., 2021). Climate health is truly a global health concern.
Supporting climate health is a key priority area in population health nursing; see Environmental Health. Participating in global nursing allows nurses to address the impact of extreme weather events on the health of the global population. Nurses can provide care that mitigates the health effects of climate events, promote policies that support global climate health, and collaborate to ensure equitable access to a healthy local and global climate.
Vaccines
In the United States, COVID-19 vaccines were available to health care workers and older adults living in long-term care facilities in late 2020 and to the general public in spring 2021. The global population of health care workers, clients, and families did not have the same timely access to vaccine s. High-income countries had purchased 54 percent of the world’s available vaccine doses by March 2021, but 81 percent of the global adult population lives in low- and middle-income countries (Stephenson, 2021). Disparities in vaccine access were detrimental to immediate and long-term global population health outcomes and contributed to avoidable deaths. Nurses addressing global population health can advocate for equitable worldwide vaccine distribution, provide education on the importance of vaccination to those who require vaccines and those who determine where vaccine clinics may be located, and provide timely access to vaccine administration (Figure 1.4).
Transportation
Access to health care can mean many things. Is there a provider or specialist in the client’s area who can adequately address the client’s health needs, and is that provider or specialist accepting new clients? Is a health care professional available who speaks the client’s native language to facilitate clarity during a health visit? Can the client physically get to a location providing health care services? Researchers recently determined that 8.9 percent of the global population is not able to access a health care provider within one hour by vehicle (Weiss et al., 2020). The time it takes a client or family to reach a health care facility can impact whether the client receives preventive health care, emergency services, and management of chronic conditions. For example, accessibility to emergency care services has a great impact on the health of people who are having a stroke, as certain medical interventions must be implemented during specific time frames from the onset of stroke symptoms (Lee et al., 2021). To support population health outcomes related to care access, nurses should contribute to developing innovative solutions for improving transportation options to ensure that people can reach facilities for care needs across the continuum. Global population health is also supported when nurses bring health care to homes and communities with low access.
In this video, Dr. Deboki Chakravarti, a science educator with the American Public Health Association, discusses global health. She addresses the major challenge in global health—helping people live the healthiest possible lives, regardless of where they live—and shares how some examples of global health problems, such as global disease eradication, food distribution, health access, and COVID-19 vaccine refrigeration, were solved via collaborative solutions.
Watch the video, and then respond to the questions that follow.
- Can you name one way in which global nursing approaches may have supported the global health topics Dr. Chakravarti shares in the video?
- What other global population health challenges are you aware of? What can nurses near to and far from the immediate health challenges do to address these problems?


1.2: Cell wall
The cell wall is initially deposited on the surface of the middle lamella. This primary cell wall occurs on the surface of all plant cells. It is substantially composed of cellulose molecules bundled together to form fibrils.
The primary cell wall is the only cell wall present in some cells. In other cells a secondary cell wall is deposited inside the primary cell wall. This secondary cell wall may contain lignin. Lignin makes the cell wall rigid and stronger. A cell membrane lies immediately adjacent to the cell wall, on the interior surface, and surrounds the contents of the cell.
To allow communication between cells there are membrane lined pores, or plasmodesmata , which run through the cell walls.


10.5: Chapter Resources
Summary
Air pollution can be thought of as gaseous and particulate contaminants that are present in the earth’s atmosphere. Chemicals discharged into the air that have a direct impact on the environment are called primary pollutants. These primary pollutants sometimes react with other chemicals in the air to produce secondary pollutants. The commonly found air pollutants, known as criteria pollutants, are particle pollution, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. These pollutants can harm health and the environment, and cause property damage. The historical record shows that the climate system varies naturally over a wide range of time scales. In general, climate changes prior to the Industrial Revolution in the 1700s can be explained by natural causes, such as changes in solar energy, volcanic eruptions, and natural changes in greenhouse gas concentrations. Recent climate changes, however, cannot be explained by natural causes alone. Natural causes are very unlikely to explain most observed warming, especially warming since the mid-20th century. Rather, human activities can explain most of that warming.
The primary human activity affecting the amount and rate of climate change is greenhouse gas emissions from the burning of fossil fuels. Greenhouse gas concentrations in the atmosphere will continue to increase unless the billions of tons of our annual emissions decrease substantially. Increased concentrations are expected to increase Earth’s average temperature, influence the patterns and amounts of precipitation, reduce ice and snow cover, as well as permafrost, raise sea level and increase the acidity of the oceans. These changes will impact our food supply, water resources, infrastructure, ecosystems, and even our own health. Acid rain is a term referring to a mixture of wet and dry deposition from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO 2 ) and nitrogen oxides (NOx) resulting from fossil fuel combustion. Acid rain causes acidification of lakes and streams, contributes to the damage of trees and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, contributes to the corrosion of metals and damages human health. The ozone depletion process begins when CFCs and other ozone-depleting substances (ODS) are emitted into the atmosphere. Reductions in stratospheric ozone levels lead to higher levels of UVB reaching the Earth’s surface. The sun’s output of UVB does not change; rather, less ozone means less protection, and hence more UVB reaches the Earth. Ozone layer depletion increases the amount of UVB tat lead to negative health and environmental effects.
Review Questions
-
Ground-level ozone…
- Protects us from radiation
- Is a primary pollutant
- Is a secondary pollutant
- Reduces visibility but is mostly harmless to human health
- Is emitted from motor vehicles
-
Secondary pollutants are pollutants…
- Emitted from non-point sources
- That are created from the reaction of primary pollutants and other chemicals
- That are less hazardous than primary pollutants
- That have reduced ability to stay aloft in the atmosphere
- Emitted by Class 2 polluters
-
Depletion of the stratospheric ozone layer occurs when molecules of ozone are destroyed by chemicals such as…
- CFC
- DDT
- O 3
- PCB
- CH 4
-
What is the function of the stratospheric ozone layer?
- Provides the biosphere with a source of elemental oxygen
- Protects against ultraviolet light
- Shields the Earth from high-energy cosmic rays
- Protects organisms from infrared radiation
- Creates UVB radiation for vitamin D synthesis
-
Anthropogenic causes of acid rain are primarily due to which one of the following?
- Destruction of the ozone layer
- Emissions of sulfur dioxide and nitrogen oxides from the combustion of fossil fuels
- Emissions of carbon dioxide from the combustion of fossil fuels
- Industrial emissions of acids
- Acids formed in the contrails of airplanes
-
The scientific consensus regarding global climate change is that these changes are…
- Caused by natural, Earth-based phenomena such as volcanoes
- Poorly understood and no scientific conclusions can be made at this time
- Primarily caused by human activities
- Caused by eccentricity in Earth’s orbit and by changes in solar intensity
- No greater or different than changes seen in the medieval times
-
Greenhouse gases are known to raise air temperatures by…
- absorbing infrared radiation
- creating heat through chemical reactions with atmospheric pollutants
- absorbing incoming visible light from the sun
- trapping high energy molecules and atomic particles
- releasing heat stored in high-altitude catalytic cycles
-
Changes in reflectivity of visible light affect how much energy enters Earth’s system. What term is used by scientists to describe the reflectivity of a surface?
- Contrastivity
- Libido
- Mirror-effect
- Alluvium
- Albedo
-
What is the primary cause of ocean acidification?
- Atmospheric CO2 dissolving in ocean water
- Increases in acid rain
- Increased erosion of acid-containing rocks
- Water draining into the ocean has a higher pH from industrial pollutants
- All of the above
-
Which one of the following is not a predicted consequence of global climate change?
- Spread of diseases carried by insects, such as malaria
- Rise in sea levels
- Increases in the global average air and ocean temperatures
- Intensity of precipitation events will likely increase on average.
- All of the above
See Appendix for answers
Attributions
CK12. (2015). Reducing ozone destruction . Accessed August 31, 2015 at http://www.ck12.org/book/CK-12-Earth...section/13.32/ . Available under Creative Commons Attribution License 3.0 (CC BY 3.0). Modified from Original.
EPA. (n.d.). Climate change. Accessed August 31, 2015 at http://www.epa.gov/climatechange/ . Modified from original.
University of California College Prep. (2012). AP environmental science. Retrieved from http://cnx.org/content/col10548/1.2/ . Available under Creative Commons Attribution 4.0 International License. (CC BY 4.0). Modified from original.
Page attribution: Essentials of Environmental Science by Kamala Doršner is licensed under CC BY 4.0 . Modified from the original by Matthew R. Fisher. “Review Questions” is licensed under CC BY 4.0 by Matthew R. Fisher.


3.6: Skills Checklist- Making an Occupied Bed
Bed making is a necessary skill for nursing assistants to keep the environment clean, prevent skin breakdown and the spread of infection, and respect the resident’s dignity by providing an orderly environment. Linens should be changed at least weekly or whenever they become soiled.
Follow these infection control guidelines when making beds:
- Never allow linens to touch your uniform.
- Do not transfer linens from one room to another.
- Do not place soiled linens on the floor.
- If clean linens touch the floor, they should be placed in the soiled laundry for cleaning and not used.
- Do not shake linens because it can spread airborne pathogens.
- Store clean linens in a closed closet or a covered cart.
Making an Occupied Bed Checklist
- Gather Supplies: Linens
- Routine Pre-Procedure Steps:
-
- Knock on the client’s door.
- Perform hand hygiene.
- Introduce yourself and identify the resident.
- Maintain respectful, courteous, and professional communication at all times.
- Provide for privacy.
- Explain the procedure to the client.
3. Procedure Steps:
-
- Place a clean barrier on a flat surface, flip linens over, and place them on the barrier so the fitted sheet is on top.
- Don gloves.
- Look for any personal belongings that may have been left in the bed and return them to their proper place.
- Put the side rail up.
- Move to the opposite side of the bed.
- Using the lift sheet, roll the resident towards the side rail.
- Begin rolling soiled linens to the middle of the bed and under the resident.
- Remove gloves.
- Perform hand hygiene.
- Place a fitted sheet on the half of the bed you are working on.
- Place the lift sheet and soaker pad in the same manner, fan folding them under the resident.
- Raise the side rail.
- Move to the opposite side of the bed.
- Put on gloves.
- Lower side rail on working side of the bed.
- Roll the resident to the opposite side.
- Remove the soiled linens and place them in a linen bag.
- Remove gloves.
- Perform hand hygiene.
- Pull through the fitted sheet, lift sheet, and soaker pad, ensuring there are no wrinkles.
- Assist the resident to a supine position.
- Keeping the resident covered, place a new flat sheet on top of them.
- Make mitered corners at the foot of the bed by doing the following:
-
-
- Tuck the entire end of the sheet under the foot of the bed.
- Facing the foot of the bed, create a 45-degree angle from the corner of the bed with the sheet.
- Place the angled sheet on top of the bed and tuck in anything hanging below the bed frame.
- Lower the angled sheet over the edge of the bed.
-
-
- Put a clean pillowcase on a new pillow and exchange it for the soiled pillow. Put the pillow at the head of the bed with the open end of the pillowcase faced away from the door. Repeat for multiple pillows.
- Repeat steps for any blankets or bedspreads.
- Make a toe pleat (i.e., a pleat in the sheet which allows an individual to move feet) to prevent pressure.
4. Post-Procedure Steps:
-
- Perform hand hygiene.
- Check on resident comfort and ask if anything else is needed.
- Ensure the bed is low and locked. Check the brakes.
- Place the call light or signaling device within reach of the resident.
- Open the door and privacy curtain.
- Perform hand hygiene.
- Report abnormal findings to the nurse.
View a YouTube video [1] of a nursing instructor demonstrating making an occupied bed:
- Chippewa Valley Technical College. (2022, December 3). Making an Occupied Bed. [Video]. YouTube. Video licensed under CC BY 4.0 . https://youtu.be/AN9pvC499P4 ↵


10.2: Deserts
Definition and Distribution
By definition, deserts are dry areas that receive less than 10 inches of rainfall per year. Although these conditions can occur at just about any geographic location, areas that are ~30° from the equator tend to be at least semiarid because this is where we have convection cells bringing dry air down from altitude. Deserts are also particularly likely to form in " rainshadow " areas in the downwind side of mountain ranges.
Processes and Deposits
In the geologic record, desert deposits can cover thousands of square kilometers and be many hundreds of meters thick. The Jurassic Navajo Sandstone and correlative units reach thicknesses of up to 700 m and widespread occurrences across Wyoming, Utah, Colorado, and Arizona represents under half of the original >340,000 mi 2 extent of the Navajo Sand Sea. And even this vast ancient desert is dwarfed by the modern Sahara Desert which covers >3.6 million mi 2 in northern Africa.
In terms of the origin of sediment within deserts, it may be derived from weathering of older (underlying) rock and sediment, fluvial transport or mass wasting from adjacent uplands, or moved by wind from other areas within the desert. The lack of water in these arid areas limits plant growth, which means that under normal conditions sediment transport is dominated by wind. Silt- and clay-sized particles can be suspended within the air and larger sand-sized particles can be temporarily suspended as well as moved by traction and saltation. Windblown sand can be organized into large sand dunes with variable morphologies; they can be up to tens of meters tall and are often preserved as very large, wedge-shaped sets of cross beds. Low-amplitude wind-ripples migrate across dune faces. When sand accumulations become oversteepened or disturbed, grain flow can happen down dune surfaces which causes inverse grading and cross-laminae that thicken downdip.
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Figure \(\PageIndex{7}\): Collection of videos showing common sediment transport processes in deserts. Clockwise from the top left they include suspension of silt and sand in a storm, saltation of sand grains, grainflow down the slipface of a dune, and movement of sediment into and across a desert by flash floods.
Interdune areas can record a variety of processes and are more sedimentologically complex. Common features in interdune areas include:
- Deflation lags (or desert pavements ) - accumulations of gravel that form when finer sediment is winnowed away leaving a gravel-armored surface behind.
- Ventifacts - faceted clasts that are created by wind erosion
- Playa lakes - temporary bodies of water that can leave behind evaporites, mud, and evidence of desiccation.
- Interdune vegetation - plants adapted to arid conditions can take root in the more stable substrate of interdune areas
- Fluvial systems - can be locally or seasonally present, especially where rivers are sourced from more distant or upland areas. Fluvial transport of sediment into deserts provides input for sediment that will eventually be reworded and transported by the wind.
Overview
Overall, desert deposits commonly consist of large, eolian cross-beds that can be much thicker than subaqueous cross-beds, low amplitude wind ripple cross laminae, deflation lags, evidence of ephemeral lakes and rivers, evaporite minerals in playas or paleosols.
Readings and Resources
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Laity, J.J., 2008, Deserts and Desert Environments, Wiley-Blackwell, 368 p., ISBN: 978-1-577-18033-3 .
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Brookfield, M. E., & Silvestro, S. (2010). Eolian systems. In N. P. James & R. W. Dalrymple (Eds.), Facies Models (4th ed., pp. 7–7). Geological Association of Canada.


9: Sequences, Probability, and Counting Theory
In this chapter, we will explore the mathematics behind situations involving probabilities and counting. We will take an in-depth look at annuities. We will also look at the branch of mathematics that would allow us to calculate the number of ways to choose lottery numbers and the probability of winning.
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- 9.1: Prelude to Sequences, Probability and Counting Theory
- A lottery winner has some big decisions to make regarding what to do with the winnings. Buy a villa in Saint Barthélemy? A luxury convertible? A cruise around the world? The likelihood of winning the lottery is slim, but we all love to fantasize about what we could buy with the winnings. One of the first things a lottery winner has to decide is whether to take the winnings in the form of a lump sum or as a series of regular payments, called an annuity, over the next 30 years or so.
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- 9.2: Sequences and Their Notations
- One way to describe an ordered list of numbers is as a sequence. A sequence is a function whose domain is a subset of the counting numbers. Listing all of the terms for a sequence can be cumbersome. For example, finding the number of hits on the website at the end of the month would require listing out as many as 31 terms. A more efficient way to determine a specific term is by writing a formula to define the sequence.
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- 9.3: Arithmetic Sequences
- In this section, we will consider specific kinds of sequences that will allow us to calculate depreciation. For example, companies often make large purchases, such as computers and vehicles, for business use. The book-value of these supplies decreases each year for tax purposes. This decrease in value is called depreciation. One method of calculating depreciation is straight-line depreciation, in which the value of the asset decreases by the same amount each year.
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- 9.5: Series and Their Notations
- The sum of the terms of a sequence is called a series. Summation notation is used to represent series. Summation notation is often known as sigma notation because it uses the Greek capital letter sigma, ∑, to represent the sum. Summation notation includes an explicit formula and specifies the first and last terms in the series. In this section, we will learn how to use series to address annuity problems.
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- 9.7: Binomial Theorem
- A polynomial with two terms is called a binomial. We have already learned to multiply binomials and to raise binomials to powers, but raising a binomial to a high power can be tedious and time-consuming. In this section, we will discuss a shortcut that will allow us to find \((x+y)^n\) without multiplying the binomial by itself \(n\) times.
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- 9.8: Probability
- Probability is always a number between 0 and 1, where 0 means an event is impossible and 1 means an event is certain. The probabilities in a probability model must sum to 1. See Example. When the outcomes of an experiment are all equally likely, we can find the probability of an event by dividing the number of outcomes in the event by the total number of outcomes in the sample space for the experiment.
Contributors
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Jay Abramson (Arizona State University) with contributing authors. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Download for free at https://openstax.org/details/books/precalculus .


14: Module 10- The Research Process—Finding and Evaluating Sources Last updated Save as PDF Page ID 58180 Lumen Learning Lumen Learning 14.1: Why It Matters- The Research Process—Finding and Evaluating Sources 14.2: Introduction to Research 14.3: What is Research? 14.4: The Research Process 14.5: Narrowing the Topic 14.6: Research Questions 14.7: Introduction to Finding Sources 14.8: Finding Sources 14.9: What are Scholarly Articles? 14.10: Reading and Using Scholarly Sources 14.11: Finding Scholarly Articles 14.12: Using Databases 14.13: Introduction to Source Analysis 14.14: Evaluating Sources 14.15: The CRAAP Method 14.16: Evaluating Websites Using the Four Moves 14.17: Annotated Bibliographies and Literature Reviews 14.18: Putting It Together- Finding and Evaluating Sources 14.19: Discussion- Narrowing the Research Topic 14.20: Discussion- Research Scavenger Hunt 14.21: Assignment- Evaluate a Source