15.19D: Other Infectious Eye Diseases
Fungi and viruses such as herpes simplex can cause eye infections.
LEARNING OBJECTIVES
Summarize the various types of herpes simplex keratitis: dendritic ulcer (epithelial keratitis) and disciform keratitis (stromal keratitis)
KEY TAKEAWAYS
Key Points
- Improper hygiene is a major cause of fungal contamination of contact lenses.
- Herpetic simplex keratitis is a form of keratitis caused by recurrent herpes simplex virus in cornea.
- Primary infection most commonly manifests as blepharoconjunctivitis i.e. infection of lids and conjunctiva that heals without scarring.
Key Terms
- ulcer : An open sore of the skin, eyes, or mucous membrane, often caused by an initial abrasion and generally maintained by an inflammation and/or an infection.
- keratitis : Inflammation of the cornea.
- conjunctivitis : An inflammation of the conjunctiva often due to infection.
Microbial corneal infection is the most serious and “most common vision threatening” complication of wearing contact lenses, which is believed to be strongly associated with contact lens cases. Such infections “are being increasingly recognized as an important cause of morbidity and blindness” and “may even be life-threatening. ” While the cornea is believed to be the most common site for fungal eye infections, other parts of the eye such as the orbit, sclera, and eyelids may also be involved.
Fungal Infections of the Eye
Factors that contribute to fungal contamination of contact lenses include, but not limited to, hygiene negligence such as: improper sterilization and disinfection of contact lenses, use of contaminated lenses, contaminated contact lens case, contaminated contact lens solution, wearing of contact lenses during eye infections and introduction of micro-organisms from the environment.
Diagnosis is determined”by recognition of typical clinical features and through direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples. “Ultimately, cultures that are made from the samples isolated from patients is what “confirms diagnosis. ” Other tests that may also be used if needed include “histopathological, immunohistochemical, or DNA -based tests. Pathogenesis of the fungal contaminants includes a wide range of factors such as invasiveness, toxigenicity, and host factors. Once diagnosis is accessed, specific anti-fungal therapy can be administered. One of the most popular and common treatments used”for life-threatening and severe ophthalmic mycoses is amphotericin B which is a specific anti-fungal drug. For the treatment for filamentous fungal keratitis, “topical natamycin is usually the first choice. For the treatment of yeast keratitis, topical amphotericin B is usually the first choice. Current advances in further treatments include evaluations of triazoles such as itraconazole and fluconazole” as therapeutic options in ophthalmic mycoses.
Viral Infections of the Eye
Herpes Simplex Virus
Herpetic simplex keratitis is a form of keratitis caused by recurrent herpes simplex virus in cornea. Herpes simplex virus (HSV) infection is very common in humans. HSV is a double-stranded DNA virus that has icosahedral capsid. HSV-1 infections are found more commonly in the oral area and HSV-2 in the genital area. Primary infection most commonly manifests as blepharoconjunctivitis i.e. infection of lids and conjunctiva that heals without scarring. Lid vesicles and conjunctivitis are seen in primary infection. Corneal involvement is rarely seen in primary infection. Recurrent herpes of the eye in turn is caused by reactivation of the virus in a latently infected sensory ganglion, transport of the virus down the nerve axon to sensory nerve endings, and subsequent infection of ocular surface. The following classification of herpes simplex keratitis is important for understanding this disease:
Dendritic Ulcer (Epithelial Keratitis)
This classic herpetic lesion consists of a linear branching corneal ulcer (dendritic ulcer). During eye exam the defect is examined after staining with fluorescein dye. The underlying corneal has minimal inflammation. Patients with epithelial keratitis complain of foreign-body sensation, light sensitivity, redness, and blurred vision. Focal or diffuse reduction in corneal sensation develops following recurrent epithelial keratitis. In immune deficient patients or with the use of corticosteroids the ulcer may become large and in these cases it is called geographic ulcer.
Disciform Keratitis (Stromal Kieratitis)
Stromal keratitis manifests as a disc-shaped area of corneal edema. Longstanding corneal edema leads to permanent scarring. It is the major cause of decreased vision associated with HSV. Localized endotheliis (localized inflammation of corneal endothelial layer) is the cause of disciform keratitis.
Diagnostic testing is seldom needed because of its classic clinical features and is not useful in stromal keratitis as there is usually no live virus. Laboratory tests are indicated in complicated cases when the clinical diagnosis is uncertain and in all cases of suspected neonatal herpes infection. Corneal smears or impression cytology specimens can be analyzed by culture, antigen detection, or fluorescent antibody testing. Demonstration of HSV is possible with viral culture. Serologic tests in turn may show a rising antibody titer during primary infection but are of no diagnostic assistance during recurrent episodes.
Treatment of herpes of the eye is different based on its presentation. Epithelial keratitis is caused by live virus. Stromal disease is an immune response. Metaherpetic ulcer results from inability of the corneal epithelium to heal. Epithelial keratitis is treated with topical antivirals, which are very effective with low incidence of resistance. Acyclovir ophthalmic ointment and Trifluridine eye drops have similar effectiveness but are more effective than Idoxuridine and Vidarabine eye drops. Topical antiviral medications are not absorbed by the cornea through an intact epithelium, but orally administered acyclovir penetrates an intact cornea and anterior chamber.
Cytomegalovirus Retinitis
Cytomegalovirus retinitis, also known as CMV retinitis, is an inflammation of the retina of the eye that can lead to blindness. Caused by human cytomegalovirus, it occurs predominantly in people whose immune system has been compromised.
Parasitic Infections of the Eye
Acanthamoeba
Acanthamoeba is a microscopic, free-living ameba (single-celled living organism) commonly found in the environment that can cause rare, but severe, eye illness. Acanthamoeba causes three main types of illness involving the eye (Acanthamoeba keratitis), the brain and spinal cord (Granulomatous Encephalitis), and infections that can spread throughout the entire body (disseminated infection).
Toxoplasma gondii
A single-celled parasite called Toxoplasma gondii causes a disease known as toxoplasmosis. While the parasite is found throughout the world, more than 60 million people in the United States may be infected with the Toxoplasma parasite. Of those who are infected, very few have symptoms because a healthy person’s immune system usually keeps the parasite from causing illness.
Signs and symptoms of ocular toxoplasmosis can include reduced vision, blurred vision, pain (often with bright light), redness of the eye, and sometimes tearing. Ophthalmologists sometimes prescribe medicine to treat active disease. Whether or not medication is recommended depends on the size of the eye lesion, the location, and the characteristics of the lesion (acute active, versus chronic not progressing). An ophthalmologist will provide the best care for ocular toxoplasmosis.
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5.9E: Proton Reduction
- Outline the role of the proton motive force in metabolism
Proton Gradients in Reductive Metabolism
Biological energy is frequently stored and released by means of redox reactions, or the transfer of electrons. Reduction occurs when an oxidant gains an electron. Photosynthesis involves the reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen. The reverse reaction, respiration, oxidizes sugars (loses an electron) to produce carbon dioxide and water. As intermediate steps, the reduced carbon compounds are used to reduce nicotinamide adenine dinucleotide (NAD+), which then contributes to the creation of a proton gradient. This then drives the synthesis of adenosine triphosphate ( ATP ) and is maintained by the reduction of oxygen, or alternative receptors for anaerobic respiration. In animal cells, the mitochondria performs similar functions.
An electrochemical gradient represents one of the many interchangeable forms of potential energy through which energy may be conserved. In biological processes, the direction an ion moves by diffusion or active transport across a membrane is determined by the electrochemical gradient. In the mitochondria and chloroplasts, proton gradients are used to generate a chemiosmotic potential that is also known as a proton motive force. This potential energy is used for the synthesis of ATP by phosphorylation. An electrochemical gradient has two components. First, the electrical component is caused by a charge difference across the lipid membrane. Second, a chemical component is caused by a differential concentration of ions across the membrane. The combination of these two factors determines the thermodynamically favorable direction for an ion’s movement across a membrane. The electrochemical potential difference between the two sides of the membrane in mitochondria, chloroplasts, bacteria, and other membranous compartments that engage in active transport involving proton pumps, is at times called a chemiosmotic potential or proton motive force.
In respiring bacteria under physiological conditions, ATP synthase, in general, runs in the opposite direction, creating ATP while using the proton motive force created by the electron transport chain as a source of energy. The overall process of creating energy in this fashion is termed oxidative phosphorylation. The same process takes place in the mitochondria, where ATP synthase is located in the inner mitochondrial membrane, so that F1 part sticks into the mitochondrial matrix where ATP synthesis takes place.
Cellular respiration (both aerobic and anaerobic) utilizes highly reduced species such as NADH and FADH2 to establish an electrochemical gradient (often a proton gradient) across a membrane, resulting in an electrical potential or ion concentration difference across the membrane. The reduced species are oxidized by a series of respiratory integral membrane proteins with sequentially increasing reduction potentials, the final electron acceptor being oxygen (in aerobic respiration) or another species (in anaerobic respiration). The membrane in question is the inner mitochondrial membrane in eukaryotes and the cell membrane in prokaryotes. A proton motive force or pmf drives protons down the gradient (across the membrane) through the proton channel of ATP synthase. The resulting current drives ATP synthesis from ADP and inorganic phosphate.
Proton reduction is important for setting up electrochemical gradients for anaerobic respiration. For example, in denitrification, protons are transported across the membrane by the initial NADH reductase, quinones, and nitrous oxide reductase to produce the electrochemical gradient critical for respiration. In organisms that use hydrogen as an energy source, hydrogen is oxidized by a membrane-bound hydrogenase causing proton pumping via electron transfer to various quinones and cytochromes. Sulfur oxidation is a two step process that occurs because energetically sulfide is a better electron donor than inorganic sulfur or thiosulfate, allowing for a greater number of protons to be translocated across the membrane.
In contrast, fermentation does not utilize an electrochemical gradient. Instead, it only uses substrate-level phosphorylation to produce ATP. The electron acceptor NAD+ is regenerated from NADH formed in oxidative steps of the fermentation pathway by the reduction of oxidized compounds. These oxidized compounds are often formed during the fermentation pathway itself, but may also be external. For example, in homofermentative lactic acid bacteria, NADH formed during the oxidation of glyceraldehyde-3-phosphate is oxidized back to NAD+ by the reduction of pyruvate to lactic acid at a later stage in the pathway. In yeast, acetaldehyde is reduced to ethanol.
Key Points
- In denitrification, protons are transported across the membrane by the initial NADH reductase, quinones, and nitrous oxide reductase to produce the electrochemical gradient critical for respiration.
- An electrochemical gradient represents one of the many interchangeable forms of potential energy through which energy may be conserved. In biological processes, the direction an ion moves by diffusion or active transport across a membrane is determined by the electrochemical gradient.
- In mitochondria and chloroplasts, proton gradients are used to generate a chemiosmotic potential that is also known as a proton motive force.
Key Terms
- phosphorylation : The process of transferring a phosphate group from a donor to an acceptor; often catalysed by enzymes


 This is a risk now on many rivers and canal systems in Illinois and Missouri because of the presence of Asian carp. This fish—actually a group of species including the silver, black, grass, and big head carp—has been farmed and eaten in China for over 1,000 years. It is one of the most important aquaculture food resources worldwide. In the United States, however, Asian carp is considered a dangerous invasive species that disrupts ecological community structure to the point of threatening native species. The effects of invasive species (such as the Asian carp, kudzu vine, predatory snakehead fish, and zebra mussel) are just one aspect of what ecologists study to understand how populations interact within ecological communities, and what impact natural and human-induced disturbances have on the characteristics of communities.
Populations are dynamic entities. Their size and composition fluctuate in response to numerous factors, including seasonal and yearly changes in the environment, natural disasters such as forest fires and volcanic eruptions, and competition for resources between and within species. The study of populations is called demography.
Population Size and Density
Populations are characterized by their population size (total number of individuals) and their population density (number of individuals per unit area). A population may have a large number of individuals that are distributed densely, or sparsely. There are also populations with small numbers of individuals that may be dense or very sparsely distributed in a local area. Population size can affect potential for adaptation because it affects the amount of genetic variation present in the population. Density can have effects on interactions within a population such as competition for food and the ability of individuals to find a mate. Smaller organisms tend to be more densely distributed than larger organisms (Figure \(\PageIndex{1}\)).
Estimating Population Size
The most accurate way to determine population size is to count all of the individuals within the area. However, this method is usually not logistically or economically feasible, especially when studying large areas. Thus, scientists usually study populations by sampling a representative portion of each habitat and use this sample to make inferences about the population as a whole. The methods used to sample populations to determine their size and density are typically tailored to the characteristics of the organism being studied. For immobile organisms such as plants, or for very small and slow-moving organisms, a quadrat may be used. A quadrat is a square structure that is randomly located on the ground and used to count the number of individuals that lie within its boundaries. To obtain an accurate count using this method, the square must be placed at random locations within the habitat enough times to produce an accurate estimate.
For smaller mobile organisms, such as mammals, a technique called mark and recapture is often used. This method involves marking captured animals in and releasing them back into the environment to mix with the rest of the population. Later, a new sample is captured and scientists determine how many of the marked animals are in the new sample. This method assumes that the larger the population, the lower the percentage of marked organisms that will be recaptured since they will have mixed with more unmarked individuals. For example, if 80 field mice are captured, marked, and released into the forest, then a second trapping 100 field mice are captured and 20 of them are marked, the population size ( N ) can be determined using the following equation:
\[N = \frac{(\text{number marked first catch} \times \text{total number of second catch})}{\text{number marked second catch}}\]
Using our example, the equation would be:
\[\frac{(80 \times 100)}{20} = 400\]
These results give us an estimate of 400 total individuals in the original population. The true number usually will be a bit different from this because of chance errors and possible bias caused by the sampling methods.
Species Distribution
In addition to measuring size and density, further information about a population can be obtained by looking at the distribution of the individuals throughout their range. A species distribution pattern is the distribution of individuals within a habitat at a particular point in time—broad categories of patterns are used to describe them.
Individuals within a population can be distributed at random, in groups, or equally spaced apart (more or less). These are known as random, clumped, and uniform distribution patterns , respectively (Figure \(\PageIndex{2}\)). Different distributions reflect important aspects of the biology of the species. They also affect the mathematical methods required to estimate population sizes. An example of random distribution occurs with dandelion and other plants that have wind-dispersed seeds that germinate wherever they happen to fall in favorable environments. A clumped distribution, may be seen in plants that drop their seeds straight to the ground, such as oak trees; it can also be seen in animals that live in social groups (schools of fish or herds of elephants). Uniform distribution is observed in plants that secrete substances inhibiting the growth of nearby individuals (such as the release of toxic chemicals by sage plants). It is also seen in territorial animal species, such as penguins that maintain a defined territory for nesting. The territorial defensive behaviors of each individual create a regular pattern of distribution of similar-sized territories and individuals within those territories. Thus, the distribution of the individuals within a population provides more information about how they interact with each other than does a simple density measurement. Just as lower density species might have more difficulty finding a mate, solitary species with a random distribution might have a similar difficulty when compared to social species clumped together in groups.
Life tables provide important information about the life history of an organism and the life expectancy of individuals at each age. They are modeled after actuarial tables used by the insurance industry for estimating human life expectancy. Life tables may include the probability of each age group dying before their next birthday, the percentage of surviving individuals dying at a particular age interval (their mortality rate, and their life expectancy at each interval. An example of a life table is shown in Table 1 from a study of Dall mountain sheep, a species native to northwestern North America. Notice that the population is divided into age intervals (column A).
As can be seen from the mortality rate data (column D), a high death rate occurred when the sheep were between six months and a year old, and then increased even more from 8 to 12 years old, after which there were few survivors. The data indicate that if a sheep in this population were to survive to age one, it could be expected to live another 7.7 years on average, as shown by the life-expectancy numbers in column E.
| Age interval (years) | Number dying in age interval out of 1000 born | Number surviving at beginning of age interval out of 1000 born | Mortality rate per 1000 alive at beginning of age interval | Life expectancy or mean lifetime remaining to those attaining age interval |
|---|---|---|---|---|
| 0–0.5 | 54 | 1000 | 54.0 | 7.06 |
| 0.5–1 | 145 | 946 | 153.3 | — |
| 1–2 | 12 | 801 | 15.0 | 7.7 |
| 2–3 | 13 | 789 | 16.5 | 6.8 |
| 3–4 | 12 | 776 | 15.5 | 5.9 |
| 4–5 | 30 | 764 | 39.3 | 5.0 |
| 5–6 | 46 | 734 | 62.7 | 4.2 |
| 6–7 | 48 | 688 | 69.8 | 3.4 |
| 7–8 | 69 | 640 | 107.8 | 2.6 |
| 8–9 | 132 | 571 | 231.2 | 1.9 |
| 9–10 | 187 | 439 | 426.0 | 1.3 |
| 10–11 | 156 | 252 | 619.0 | 0.9 |
| 11–12 | 90 | 96 | 937.5 | 0.6 |
| 12–13 | 3 | 6 | 500.0 | 1.2 |
| 13–14 | 3 | 3 | 1000 | 0.7 |
Another tool used by population ecologists is a survivorship curve , which is a graph of the number of individuals surviving at each age interval versus time. These curves allow us to compare the life histories of different populations (Figure \(\PageIndex{3}\)). There are three types of survivorship curves. In a type I curve, mortality is low in the early and middle years and occurs mostly in older individuals. Organisms exhibiting a type I survivorship typically produce few offspring and provide good care to the offspring increasing the likelihood of their survival. Humans and most mammals exhibit a type I survivorship curve. In type II curves, mortality is relatively constant throughout the entire life span, and mortality is equally likely to occur at any point in the life span. Many bird populations provide examples of an intermediate or type II survivorship curve. In type III survivorship curves, early ages experience the highest mortality with much lower mortality rates for organisms that make it to advanced years. Type III organisms typically produce large numbers of offspring, but provide very little or no care for them. Trees and marine invertebrates exhibit a type III survivorship curve because very few of these organisms survive their younger years, but those that do make it to an old age are more likely to survive for a relatively long period of time.
Contributors and Attributions
- Population Demography by OpenStax is licensed under CC BY 4.0. Modified from the original by Matthew R. Fisher.


22.2: Online Labs
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Online (or virtual) labs simulate traditional settings, and sometimes take students beyond what can be done in a traditional lab. In general, there are two types of labs. One simulates real experiments, equipment, or procedures, while the other lets learners access and control real equipment from a remote location. These are different from software simulations that emulate real-world scenarios such as investing money, controlling power plants, and flying airplanes. An online lab is not created simply by transferring a lab workbook to a website, allowing students to access software from different campus or off-campus locations or enabling them to submit assignments via the Internet. In this chapter, the term “lab” is used generically for any setting where practical skills are taught, such as in labs, shops, and classrooms.
Some online labs let you simulate lab procedures or equipment. For example, using the computer’s mouse, students can get a beaker, put a precise amount of a specific chemical in it, and virtually carry out all of the needed procedural steps. This is useful for preparing students to carry out lab procedures efficiently in a reallife lab. One problem is that online labs are much more valuable if the learner can also see the results. It would be ideal to let learners virtually mix chemicals and to provide opportunities that would be too costly or dangerous to carry out in a real lab. However, as the number of variables increases, the complexity of online lab design and possibilities increase. Imagine all of the possibilities with all of the different chemicals mixed together in different volumes, concentrations, combinations, and sequences. You could theoretically state what would happen for each case but, for practical reasons, students would not be able to see a video clip or animation of each possibility.
Problems with Teaching Lab Skills in Traditional Way
There can be numerous problems when teaching practical skills in typical face-to-face labs:
- When a demonstration is done, some students, such as those in the back of the class, may not be able to clearly see what is being demonstrated.
- Many instructors will not show all of the possible demonstrations, due to time, cost, or equipment limitations.
- Dangerous, expensive, or unavailable equipment or materials may limit what learners can see or do.
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The costs of building and maintaining labs are high.
- Even if a lab can be built, funds are still needed to run labs. Staff, materials, and equipment replacement due to breakage as well as wear and tear are significant. Equipment upgrades are also a costly, important consideration.
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It may not be possible or practical to teach some skills.
- For example, one way to teach troubleshooting involves taking components out of functioning systems, breaking them, putting them back in, and letting students determine the problem. However, this is impractical because of the time it takes to remove, break, and install components, cost of later repairing the components, problem that this needs to be done to many components, and time required to have all of the students individually determine the problem for each broken component.
- In many cases, if a student misses a lab, they will not have the opportunity to do it later.
- Students are often not able to repeat a lab if something goes wrong. This is often due to time constraints.
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Existing media, needed to teach practical skills, may not be easily available.
- A common illustration of this is where a repair person may need to see a series of video clips or photographs while working on equipment.
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Some existing traditional teaching materials that are used in labs are not effective.
- In one case, a 20-minute videotape was created to train student mechanics how to disassemble and assemble an aircraft engine. However, the total disassembly and assembly requires approximately 200 steps. The videotape did not provide the details that the students needed.
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It may not be possible to offer live training.
- Logistical challenges can arise when experts do not have enough time to travel to reach learners or even to simply have the time to teach (i.e., there is no extra time in their full-time job).
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Learners may not be able to attend live training locations.
- This is an inherent problem in distance education. Many learners can learn the theory online or through other distance education solutions. However, they may not be able to learn the needed practical skills at a distance. Yet, these practical skills are often essential for enhancing learning.
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Costs to attend live training can be high.
- This can be seen when numerous participants are required to travel to a workshop.
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There may be a need for just-in-time learning.
- There are many times when a learner needs immediate training and cannot wait for a course or workshop to become available or be completed.
Given sound instructional design strategies, technology has solved these problems. For example, online labs can:
- show close-ups of procedures that all can see
- show extra demonstrations
- contain an individual’s expertise
- offer alternative instructional approaches
- eliminate the costs of travelling to face-to-face labs
- be available when and where a student wants
- show expensive or dangerous procedures as the procedures would only have to be done once for the recording session and would then be available as needed
- include media, especially short, step-by-step video clips to illustrate specific concepts or procedures such as disassembling and assembling an aircraft engine.
- provide “just-in-time” learning
Instructional Design for Online Labs
The general principles of instructional design apply to all educational materials. However, when designing online labs, there are other things to consider. These are discussed below.
Learning outcomes
Consider what the learner really needs to learn rather than what you want to teach or have traditionally taught. More specifically, for practical skills, determine what the learner actually needs to do. One way to do this is by imagining what skills the learner needs in the real world. To illustrate this, in some cases in the laboratory portion of chemistry, the learner does not really need to pour one chemical into another. The important skills relate to the observations, data analysis, and conclusions that are drawn. For teaching practical troubleshooting skills, the needed skill may be the ability to analyze the interrelationships between components of the system. Regardless, of the application, an online lab should simulate the actual practical skills needed to ensure that learning is authentic. In other words, online labs should focus on skills needed in the real world.
Note
Focus on what the learner really needs to learn. Previously taught skills may not be relevant.
Creating the instructional strategy
The instructional challenge is to ensure that the practical skills taught via the computer transfer to the real world. Evidence supports that, with solid instructional design, this can be done. The foundation for the instructional design is the learning outcomes. The learning outcomes, lead to the design of the instructional strategy—what needs to be done to ensure that the students will effectively and efficiently learn.
For the instructional strategy, determine how to ensure that most all learners will learn effectively. This is a particular challenge when students are on their own and cannot have their questions immediately answered. Think outside the box to guarantee learning. Consider simulation, discovery-learning techniques, and active experimentation. Page-turning activities will not suffice for learning many practical skills. Use the technology for its strengths rather than simply transferring content from one format to another.
Note
The key is to determine what needs to be done to ensure effective learning will occur.
Think about the limitations of teaching each skill online. You will have to realistically determine what level of skill you can achieve. For example, in an online biology lab, how would you teach a student to learn how to use a microscope? This is a limitation of using online technology. However, a lot can be done with visual media. You could show the coarse adjustment being used to focus an image, then show what would be seen inside the ocular lens, then show fine adjustments being made, and then what the learner would see inside the ocular lens. A practical activity could have the learner clicking on arrows to move the coarse and fine adjustments (clockwise and counter-clockwise) and see the corresponding image of what would be seen. The goal would be to find the clearest image. Video clips and activities can similarly be used for demonstrating other microscope components, such as the condenser lens. This would not be as good as what is done in a real lab, but would definitely give a sense of how a real microscope works.
Other activities could potentially lead to better results than a real lab. As a comparison, in a real lab, students see specimens and are then asked to draw what they see so that they can later study from their drawings. In an online lab, students will see full-colour video clips and photographs that they can later study for their lab test. One key in creating a successful online lab is getting as close as possible to reality (given constraints of time and money).
A part of the instructional strategy is to organize the information into small enough chunks for the students to successfully learn. A typical need for this is when a procedural skill has numerous steps. If so, consider teaching the entire process in logical groups of three to six steps. Many instructional resources provide too much information or too many steps for students to learn at one time.
Instructional strategies should include some content on the potential avenue for making mistakes. Ask the content expert about typical mistakes made after the content is taught in the traditional way. If one only teaches what is correct, the learner may never learn what can go wrong. Teaching what can go wrong is helpful in teaching students about safety in chemistry labs.
Note
Address potential mistakes that learners make in live labs.
Teaching practical skills via computer usually requires a variety of specific media to enhance learning as well as to test skills. It is often difficult to test practical skills with only text. Plan in advance to record photographs and video clips of skills done incorrectly. These become excellent resources for testing. One challenge will be in creating the media needed since live labs typically depend on some copyrighted material. It is not safe to assume that you can get copyright clearance from the originators, especially if you plan to sell the product.
Determine whether assessment is realistic as a true measure of performance. This is particularly important for practical skills. When testing, consider all difficulty levels. Many existing technology-based resources are weak in that they only address low-level thinking skills rather than the actual skills needed.
Make the program highly interactive throughout. Interactivity requires the learner to actively think while learning. Creating interactions in the virtual environment is easily done. You can have students drag and drop items, increase and decrease settings to observe results, make decisions and see consequences, and answer questions based on video clips and photographs showing correct and incorrect procedures or results. Remember to always provide detailed feedback, even when the answer is right. This is in case the student guessed the correct answer or answered correctly for the wrong reason(s).
Note
Ensure that you keep the learner engaged and thinking throughout.
Controlling Real Equipment
Virtually controlling real equipment can be challenging. One problem is enabling control across computer platforms. Although it is not trivial, it can be solved with web-based tools that are designed for interoperability and machine-to-machine interaction over a network. However, this is a major problem if the equipment is not designed for remote access. Virtual control may require a lab technician for some tasks such as preparing and loading samples. Will this need to be done 24 hours per day and seven days per week? It is hard to generalize whether the overall labour, materials, and facilities costs will be higher for live labs or virtual labs that enable remote control of real equipment.
There may be some logistical problems with allowing remote access to equipment. Imagine if 100 students signed up for a course that included remote access to equipment. Consider 1,000 virtual students. Can large numbers of virtual students be supported? What if “live” students also need to access the equipment? What happens if a virtual student wants to access equipment that another virtual student is using? How does a lab technician support more than one virtual student at a time? When will the equipment be available for virtual students? How many units will be available for remote control?
Note
Determine the logistics, benefits, and costs of virtually controlling real equipment before taking on such a project.
Handling Lab Tests
Lab tests can be done any way you want. You can:
- Have students come to campus to be tested in a live lab. However, this would prevent some students from being able to complete an online program.
- Require students to write paper-based exams. It may be that only a portion of the skills could be adequately tested in a paper-based format. Invigilation may need to be addressed.
- Have learners complete a computer-delivered test. The test could be wholly or partially based on learning objects, especially video clips and photographs, already used in the online lab. Invigilation may need to be addressed.
Articulation
Articulation may be an issue. Some people will simply be adverse to change, or assume that an online lab is inferior to a live lab. Other people will argue that you cannot replace the real thing, or that some things cannot be simulated online. (Sometimes the sense of touch and smell play important roles in learning.) Since most online labs only show the correct results, some will resist online labs because an advantage of actual labs is that significant learning takes place through mistakes that students make. (You can disarm that argument by addressing typical errors in your designs.) Yet others will need research confirmation of effective results before accepting the technology. The good news is that some are claiming that online labs can be rigorous enough to be equivalent to actual labs. An online lab you create might initially only be approved for a limited group of students (e.g., non-science majors).
You will need to gain the support of all stakeholders. You can foster initial acceptance by involving articulation committee members in the formative evaluation and later conducting a summative evaluation. With successful results in a summative evaluation, it is more likely that there will be approval for any student to learn via an online lab. Articulation is more fully discussed in Chapter 12, Articulation and Transfer of Online Courses.
Note
Do what you can to ensure you get the support of the articulation committee.
The Future of Online Labs
It is difficult to predict the future of online labs. However, the reality is that online labs will continue to be created. Some will be of minimal value while others will effectively meet the needs of distance learners and solve the previously mentioned problems of live labs. Some questions will need to be answered:
-
Can all labs, ranging from introductory to advanced, be delivered online?
- In some courses, all of the lab skills can be successfully delivered online, while in others the labs should only be offered live. There is a limit to how much can be conducted online. Would it be reasonable for a student to get a biology degree without ever working with real specimens and a real microscope and other lab equipment? It is likely that everyone would answer this question with a resounding “No”.
-
Will administrators of post-secondary institutes or the government require the use of online labs to save costs?
- Only time will tell. Already many institutions have opted to have labs every second week. The official rationale is that this enables students to be better prepared for labs. The reality is that it is to save costs. One option is to conduct every second lab online. This would accommodate a larger number of students when there are limited lab resources. Note that some governments have already applied pressure to eliminate some labs.
- Another option is to use online labs to speed up lab time. If students know exactly what procedures they will be doing online, they can spend less time in the live lab, thus freeing up room for more students.
Note
Be ready to answer questions about the effectiveness and economy of an online lab.


9.4: Collaboration
When each of us gives our best self to the group we are able to achieve incredible things. As a director it helps if you have experience in as many areas of theatre as possible. The more experience you have in various areas, the more you able to understand the artistry each contributor brings to the project and you are able to appreciate the effort it takes in order to produce each contribution.
I always used to think that students took my classes because of the information they were receiving. I am proud of the rigor of my curriculum and am constantly pushing my students to strive to be the best versions of themselves. Yet everytime I hear my students talk about why they love theater or keep coming back to the theater, the only answer I ever hear is the relationships they make while creating theater. I think that is why we all love theater, it is the place where we find that our ideas matter, that it is ok to take chances, that failure is an opportunity to learn and improve, and where we ultimately find our tribe. Theater is a collaborative art form and as the leader of a production always remember that the relationships we create during the process are more important than the quality of the production.


5.1A: What is Skin?
The skin is the soft outer covering of vertebrates that guards the underlying muscles, bones, ligaments, and internal organs.
LEARNING OBJECTIVE
Identify the layers of the skin
Key Takeaways
Key Points
- The outer layer of skin, the epidermis, provides waterproofing and serves as a barrier to infection.
- The middle layer of skin, the dermis, contains blood vessels, nerves, and glands that are important for our skin’s function. The inner layer of the skin, the subcutis, contains fat that protects us from trauma.
Key Terms
- epidermis : The outermost layer of the skin.
- subcutis : The inner layer of skin that is also called the hypodermis or subcutaneous layer.
- dermis : The middle layer of the skin.
- cutaneous membrane : The formal name for the skin.
The Cutaneous Membrane
The cutaneous membrane is the technical term for our skin. The skin’s primary role is to help protect the rest of the body’s tissues and organs from physical damage such as abrasions, chemical damage such as detergents, and biological damage from microorganisms. For example, while the skin harbors many permanent and transient bacteria, these bacteria are unable to enter the body when healthy, intact skin is present.
Our skin is made of three general layers. In order from most superficial to deepest they are the epidermis, dermis, and subcutaneous tissue.
The Epidermis
The epidermis is a thin layer of skin.  Functions of the epidermis include touch sensation and protection against microorganisms.
This skin is further divided into five, separate layers. In order from most superficial to deepest, they are the:
- Stratum Corneum
- Stratum Lucidum
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale
Stratum Corneum
This layer is composed of the many dead skin cells that you shed into the environment—as a result, these cells are found in dust throughout your home. This layer helps to repel water.
Stratum Lucidum
This layer is found only on the palms of the hands, fingertips, and the soles of the feet.
Stratum Granulosum
This is the layer where part of keratin production occurs. Keratin is a protein that is the main component of skin.
Stratum Spinosum
This layer gives the skin strength as well as flexibility.
Stratum Basale
This is where the skin’s most important cells, called keratinocytes, are formed before moving up to the surface of the epidermis and being shed into the environment as dead skin cells.
This layer also contains melanocytes, the cells that are largely responsible for determining the color of our skin and protecting our skin from the harmful effects of UV radiation. These harmful effects include burns in the short term and cancer in the long run.
The Dermis
Underneath the epidermis lies the dermis. The dermis contains:
- Blood vessels that nourish the skin with oxygen and nutrients. The blood vessels also allow immune system cells to come to the skin to fight an infection. These vessels also help carry away waste products.
- Nerves that help us relay signals coming from the skin. These signals include touch, temperature, pressure, pain, and itching.
- Various glands.
- Hair follicles.
- Collagen, a protein that is responsible for giving skin strength and a bit of elasticity.
The Subcutaneous Tissue
The deepest layer of the skin is called the subcutaneous layer, the subcutis, or the hypodermis. Like the dermis, the layer contains blood vessels and nerves for much the same reasons.
Importantly, the subcutis contains a layer of fat. This layer of fat works alongside the blood vessels to maintain an appropriate body temperature. The layer of fat here acts as a cushion against physical trauma to internal organs, muscles, and bones.
Additionally, the body will turn to this fat in times of starvation to provide power to its various processes, especially brain function.
Layers of cutaneous membranes (skin): This image details features of the epidermal and dermal layers of the skin.


2.9: Assignment- “What’s in My Computer?” Group Discussion Forum
Assignment Objective
Part A
Identify the hardware components in your own computer. If you don’t have a computer, use a friend’s, or one at work or in a computer lab. The following list shows the components you should identify and how to find the information on a Windows computer. If you have a Mac, your job is probably easier. Until recently, Macs were standard hardware models produced by Apple. You can look up the technical information for your model in your documentation, or on the Apple web site, or with the free downloadable Mactracker database.
- Input devices (include internal and external devices) – they usually have a model name and number somewhere on the device.
- Output devices (include internal and external devices) – they usually have a model name and number somewhere on the device.
- Storage devices (include internal and external devices, and how much data each can hold) – Open Windows Explorer and right click on a drive name to open its properties.
- Amount of RAM – Open System Properties in the Windows Control Panel.
- Type and speed of CPU – Open System Properties in the Windows Control Panel.
- Ports (number and type) – Look for jacks into which a connector can be plugged on the front, back and sides of the machine. Compare the jacks to pictures in your textbook.
- Write a list of the parts in your computer system for each category specified above.
 You only have access to your own group’s forum. If you don’t have access to any group forum, please contact me immediately.
- Open the group discussion board and post your response in the “What’s in my Computer” forum.
Part B
- Read the other postings in your group’s forum.
- Respond to at least two postings in your group other than your own. State whether you would make any recommendations, what you would recommend and why.
- Read the responses to your own report.
CC licensed content, Original
- Introduction to Computer Applications and Concepts Hardware Discussion Forum. Authored by : Jim Shannon. Provided by : Extended Learning Institute of Northern Virginia Community College. Located at : http://www.nvcc.edu/eli/index.html . License : CC BY: Attribution


<IP_ADDRESS>: Mortgages
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What’s on This Page
Mortgage Refinancing
Refinancing refers to satisfying a debt by making another loan on new terms. The most common consumer refinancing is for a home mortgage, which generally involves paying off your existing mortgage and taking out a new mortgage.
The following resources provide further information:
- A Consumer’s Guide to Mortgage Refinancings
- Buying Your Home: Settlement Costs Booklet (PDF, Download Adobe Reader )
- Interest Rate Reduction Refinancing Loans (IRRRL) – For Veterans
Making Home Affordable Program
The Making Home Affordable Program offers opportunities to modify or refinance your mortgage to make your monthly payments more affordable. It also includes the Home Affordable Foreclosure Alternatives Program for homeowners who are interested in a short sale or deed-in-lieu of foreclosure. Call 1-888-995-4673 for more information.
Please note: New Federal Reserve rules require mortgage companies to notify homeowners when their loans are transferred to another company. The company that takes over your loan must send you a notice within 30 days of acquiring it. Even with a new loan owner, the company that “services” or handles your loan might not change and you might continue to send your payments to the same address. If that loan servicer changes, you will receive a separate notice.
For more information about servicing companies, read the Federal Trade Commission’s publication “Mortgage Servicing: Making Sure Your Payments Count.”
Predatory Loans
Most mortgage professionals are trustworthy and provide a valuable service, helping you to buy or refinance your home. But dishonest or “predatory” lenders do exist and engage in practices that increase the chances of borrowers losing their homes to foreclosure. To avoid becoming a victim of predatory lending, you need to understand the process to buy a home and be a smart consumer.
What Is Predatory Lending?
Predatory lenders, appraisers, mortgage brokers and home improvement contractors could use any of these tactics to take away your home or investments:
- Sell properties for much more than they are worth using false appraisals
- Encourage borrowers to lie about their income, expenses, or cash available for down payments in order to get a loan
- Knowingly lend more money than a borrower can afford to repay
- Charge high interest rates to borrowers based on their race or national origin and not on their credit history
- Charge fees for unnecessary or nonexistent products and services
Avoid Predatory Loans by Being a Smart Consumer
Follow these guidelines to avoid becoming a victim of predatory lending:
- Before you buy a home, attend a homeownership education course offered by a U.S. Department of Housing and Urban Development (HUD)-approved, non-profit counseling agency.
- Interview several real estate professionals (agents), and ask for and check references before you select one to help you buy or sell a home.
- Get information about the prices of other homes in the neighborhood. Don’t be fooled into paying too much.
- Hire a qualified and licensed home inspector to carefully inspect the property before you are obligated to buy. Determine whether you or the seller will be responsible for paying for the repairs.
- Shop for a lender and compare costs. Be suspicious if anyone tries to steer you to just one lender.
The HUD Office of Housing Counseling has a list of federal, state, and local resources to protect you from predatory lending.
Reverse Mortgages
A reverse mortgage is a home loan that you do not have to pay back for as long as you live in your home. You only repay the loan when you die, sell your home, or permanently move away. Homeowners who are at least 62 years old are eligible. These mortgages allow older homeowners to convert part of the equity in their homes into cash without having to sell their homes or take on additional monthly bills.
Read more information about reverse mortgages .
Types of reverse mortgages include:
- Federally insured Reverse Mortgages – Known as Home Equity Conversion Mortgages (HECM)
- Proprietary Reverse Mortgages
- Single Purpose Reverse Mortgages
Be sure to watch for aggressive lending practices, advertisements that refer to the loan as “free money,” or those that fail to disclose fees or terms of the loan. To be a savvy consumer and help protect yourself, remember:
- Do not respond to unsolicited advertisements
- Be suspicious of anyone claiming that you can own a home with no down payment
- Seek out your own reverse mortgage counselor
- Never sign anything you do not fully understand
- Make sure the loan is federally insured
Reporting Fraud or Abuse
If you suspect fraud or abuse, let the counselor, lender, or loan servicer know. You may also file a complaint:
If you have questions, contact your local Homeownership Center for advice.
Contributors and Attributions
- Authored by : USA.gov. Located at : https://www.usa.gov/mortgages . License : Public Domain: No Known Copyright


1.14.7: Boundary
The term ‘boundary’ is encountered in several contexts in thermodynamics. Indeed the definition becomes more complicated as we concentrate on the thermodynamic properties of systems.
As a starting point, a boundary separates system and surroundings. A boundary is an infinitely thin surface separating system and surroundings such that the properties of system and surroundings change abruptly at the boundary. [1,2] In these terms a reaction vessel is part of the surroundings. We support this careful distinction by observing that if chemical reaction inside the system is exothermic, the liberated heat warms the reaction vessel. In this case, the boundary encloses the system. No molecules can either enter or leave the system. However heat is allowed to cross the boundary. Thus the whole universe is divided into system and surroundings [3], the only role of the boundary is to facilitate communication between system and surroundings. In these terms chemical substances, heat, and electric charge may cross a boundary between a system and surroundings.
In some cases the container (e.g. reaction vessel) may be considered part of the system. In many cases [4,5] it is correct to do so and so the boundary is again a hypothetical surface separating ‘reaction solution + reaction vessel’ and the surroundings.
In general terms, it is important to define the boundary for a given system. Another term for boundary is ‘envelope’ which indicates something which can be quite dynamic in terms of shape and volume rather than, for example, a glass vessel. Moreover the boundary may be selectively permeable to one or more chemical substances rather like the envelope of unit cells in living systems [6].
The term ‘boundary’ in the context of surface chemistry means a boundary phase (or, capillary phase) [7]. In such a phase there is a concentration gradient of one or more chemical substances across the boundary phase between system and surroundings. Indeed surface chemistry can be described as the chemistry of boundaries.
In summary we repeat the point that in a thermodynamic analysis of experimental results, a first requirement is that the system, boundary and surroundings are carefully defined. For the most part we assume that the boundary is an infinitely thin envelope separating system and surroundings.
Footnotes
[1] K. S. Pitzer, Thermodynamics, McGraw-Hill, New York,1995, 3rd. edn., page 6.
[2] G. N. Lewis and M. Randall, Thermodynamics, McGraw-Hill, New York, 1923, page 10.
[3] D. H. Everett, Chemical Thermodynamics, Longmans, London, 1959, page 8.
[4] M. L. McGlashan, Chemical Thermodynamics, Academic Press, London, 1979,page 1.
[5] E. B. Smith, Basic Chemical Thermodynamics, Clarendon Press, Oxford, 3rd. edn.,1982, page 2.
[6] S. E. Wood and R. Battino, Thermodynamics of Chemical Systems, Cambridge University Press, Cambridge, 1990, page 3.
[7] J. N. Bronsted, Physical Chemistry, Heinemann, London, 1937, page 359.


14.5: Afterbeats and Offbeats
14.5 Afterbeats and Offbeats
14.5.1 Afterbeats
The term “afterbeats” is from Fundamentals of Musical Composition by noted composer and pedagogue Arnold Schoenberg. “ Afterbeats ” are repeated chords (usually eighth notes, sometimes quarter notes) that occur after the downbeat.
In the next example, the afterbeats are not repeated chords but instead are passing-tone figures harmonized in thirds.
14.5.2 Offbeats
Offbeats are typically chords that occur regularly on upbeats, avoiding downbeats. While there are many styles of music that use chordal offbeats, in this section we will consider only polka and reggae styles.
<IP_ADDRESS> Polka
The polka, which originated in Bohemia, has connotations with Germary and Oktoberfest. The polka in the United States is often associated with Frankie Yankovic, who was known as the “Polka King.”
<IP_ADDRESS> Reggae
Reggae is associated with the island of Jamaica and, in terms of texture, is characterized by offbeats, often played on an electric guitar. Bob Marley is closely associated with reggae music.
By the late 1970s, British bands like The Police and UB40 were recording songs that used the reggae accompanimental style.
Reggae accompanimental texture is fairly common in the present day, as can be heard in the following examples.


1.38: Self-Assessment Modules 23–30
Self-Assessment Modules 23–30
© 2021 Philip S. Peek, CC BY 4.0 https://doi.org/ 10.11647/OBP.0264. 38
Rate yourself on a scale of 1 to 10, where 10 represents mastery and 1 its opposite. Answer each of the below thoughtfully. For any score less than a 7, review the material.
MEMORY
- Have I memorized all of the high-frequency vocabulary?
- Have I memorized all of the endings for noun ending sets 1–10?
- Have I memorized the verb endings for μι -verbs and for ω -verbs ?
- Have I memorized the verb forms for εἰμί , εἶμι , and οἶδα ?
- Have I memorized how the vowels combine in contract verbs?
- Have I memorized the personal pronouns?
- Have I memorized τίς , τί ; τις , τι ; and the common adjectives and pronouns?
APPLICATION AND CONCEPTS
- Can I define the 8 parts of speech and pick out the function of each in sentences in English and in Greek?
- Do I understand how endings create meaning?
- Can I apply the Case and Function Chart when reading and translating?
- Can I define and explain the following verb qualities: person, number, tense, aspect, mood, and voice?
- Can I define and explain deponent verbs?
- Can I define and explain transitive and intransitive verbs?
- Can I define an infinitive and explain how it functions in indirect statements and in result clauses?
- Can I define an infinitive and explain its function as a complementary infinitive, epexegetical infinitive, and objective infinitive or infinitive of dependence?
- Can I define and explain noun and adjective agreement?
- Can I define and explain substantive adjectives?
- Do I understand how word order creates meaning in attributive and predicate position?
- Do I understand how word order is important but not decisive in the way that noun and pronoun endings are decisive?
READING AND TRANSLATING
- Do I read the sentences in Greek one or more times before I start to translate?
- As I translate, am I able to identify endings and vocabulary with ease?
- Do I have a sense for how a sentence develops meaning from beginning to end?
- Do I check my translations with the answers?
- Do I read through the Greek sentences two or more times after I have an accurate understanding of each sentence’s meaning?
- Can I parse each word in a sentence?


10.5: Post-test
- True or False: Maintaining a clean home helps to prevent the spread of bacteria, viruses, and fungus, and helps promote good mental and physical health.
- True or False: Patient belongings should be carefully handled and care should be taken to put objects back where they were found. Furniture and belongings should not be rearranged unless the patient specifically asks.
-
When standing, you should have your feet about this many ____________ inches apart.
- 10 inches
- 20 inches
- 12 inches
- 5 inches
- True or False: Providing personal care and meeting patient needs are a priority for the HHA/PCA. However, proper planning and prioritizing tasks will allow the HHA/PCA to provide personal care and complete required household cleaning tasks.
-
Which of the following is the priority task?
- Laundry
- Preparing lunch for the patient
- Patient needs to be turned and positioned and offered the bed pan.
-
Which of the following demonstrate proper body mechanics?
Select
all
that
apply
.
- Turn your entire body instead of twisting your back when moving objects or people.
- Maintain good posture.
- Raise beds to working height and avoid leaning over patients to perform tasks.
- Keep feet hip width apart to provide a strong base of support.
- Bend at the hips and knees instead of the waist when lifting.
-
Abrasive cleaners are appropriate for which type of surface?
- Stainless steel sinks and stovetops
- Windows
- Wood floors
- Porcelain bath tubs
- True or False: It is okay to mix bleach or ammonia with other cleaners as the combined effects will make a very good disinfectant solution.
- True or False: To remove an electrical appliance such as a vacuum from an electrical outlet, you should remove it by holding the base of the plug and not the cord.
- True or False: Bleach can be used on any surface or type of clothing as a disinfectant.
- True or False: Bath mats, rugs, and towels should be picked up immediately after use to prevent falls.
-
Which of the following is the
priority
task
when performing household duties?
- Folding clean laundry
- Making the patient’s bed
- Closing off the kitchen area from use after it has just been mopped
- Vacuuming the living room
- Answer
-
1. True
2. True
3. C
4. True
5. C
6. All are proper body mechanics
7. A
8. False
9. True
10. False
11. True
12. C


2.6: Fairytale Relay
Serves: 15 Players
Cook Time: 20 min
Ingredients
10 - 20 Players
Instructions
- Players are broken into groups of 3 to 5
- Instructor stands/sits in middle of room evenly distant from each group that is stationed in the corners of the room/space.
- Instructor is holding cards with well known or reviewed fairytales.
- One player from each group runs up and looks at the card and begins ‘acting out’ the fairytale until their group guesses.
- Once a group guesses the fairytale the player runs back to the Instructor and grabs the card, returns to their group and a new player begins the whole process again.
Notes
Players cannot communicate in any other way other than physical, no mouthing words. Players must return to their group before acting out the fairytale, no stopping half way to group in order to eliminate distance to retrieve card from Instructor.