5.9: Job Descriptions
- Identify the elements of a job description
- Differentiate among job analysis, job descriptions and job specifications
A job description is a written statement of what a position entails: what is done, how it’s done and under what conditions. Wright State University’s Human Resources department notes that “when well-written, [a job description] produces a realistic picture of a job and answers the question, “What does the person in this role actually do?” [1] In addition to describing the responsibilities of the position, a job description is the primary reference document for recruiting and evaluation. To that point, WSU notes it “sets the stage for optimum work performance by clarifying responsibilities, expected results, and evaluation of performance.” As is true of a job analysis, a job description should be “incumbent neutral;” that is, a classification of the position, without reference to a specific person in that position.
Elements of a Job Description
Although layouts vary, job descriptions generally include the following elements:
- Job Title. Job title and other reference information such as a job code.
- Reporting Relationships. Identification of the department the job is a part of, the position the role reports to and any supervisory responsibilities (i.e., number of staff supervised).
- Job Summary. A brief (1–2 sentence) overview of the role, including its purpose, level and scope of responsibility.
- Essential Functions. A representative description of the essential tasks, duties and responsibilities of the position. Although in templates this section is often titled “Job Duties and Responsibilities,” using the terminology “essential functions” reinforces the point that these are considered “must have” capabilities. That is, they are required for the successful performance of the job and cannot be modified. For fairness and legal defensibility, these should include all but only those specific skills or abilities that are necessary. Employers who do not have job descriptions with current, defensible essential functions may find themselves unable to defend against a claim of discrimination.
- Job Specifications. This section identifies the minimum acceptable qualifications for the job including education, experience, and specialized knowledge or skills, if applicable. If applicable, a job description may also list a few preferred qualifications, which may reflect a preference for additional education, experience, knowledge, skills or ability. For example, the job may specify a minimum of a bachelor’s degree but list a preference for a master’s degree or a Human Resource certification.
For a point of reference, refer to Workforce’s sample job description for a HR Manager. For perspective, CareerBuilder states that “the key to writing effective job descriptions is to find the perfect balance between providing enough detail so candidates understand the role and your company while keeping your description concise,” noting that job descriptions that range between 700 and 2,000 characters receive up to 30% more responses. [2] Potential shortcut: SHRM offers members free sample job description templates organized by title and function.
Job Analysis vs. Job Descriptions vs. Job Specifications
A job analysis is an internal document that serves as the basis for both job descriptions and job specifications. As discussed in the prior section, a job description summarizes key details of the job, including its purpose, essential functions and job specifications. Job specifications are a subset of the job description that detail the minimum acceptable qualifications for the job. For an illustration of this, refer to Table 1.
| Job Description | Job Specifications |
|---|---|
| Job Title | Qualifications |
| Job Location | Experience |
| Job Summary/Duties/Responsibilities | Training |
| Reporting to | Skills |
| Working conditions/Hazards | Emotional Characteristics |
A key distinction is that the details listed under job description are not personal; they are aspects of the job. That is, the job description is what is to be done. Job specifications reflect what’s required to complete the job and are personal in the sense that each candidate or employee will have a different job specification profile or combination of education, experience and expertise. Note that a job description may also feed back into the job analysis as a source document when a job is being reviewed or updated.
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"
Writing an Effective Job Description
." Wright State University. Accessed September 12, 2019. ↵
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How to Write a Job Description
." Indeed. Accessed September 12, 2019. ↵


2.2: Graphs of Linear Functions
When we are working with a new function, it is useful to know as much as we can about the function: its graph, where the function is zero, and any other special behaviors of the function. We will begin this exploration of linear functions with a look at graphs.
When graphing a linear function, there are three basic ways to graph it:
- By plotting points (at least 2) and drawing a line through the points
- Using the initial value (output when x = 0) and rate of change (slope)
- Using transformations of the identity function \(f(x)=x\)
Graph \(f(x)=5-\dfrac{2}{3} x\) by plotting points.
Solution
In general, we evaluate the function at two or more inputs to find at least two points on the graph. Usually it is best to pick input values that will “work nicely” in the equation. In this equation, multiples of 3 will work nicely due to the \(\dfrac{2}{3}\) in the equation, and of course using \(x = 0\) to get the vertical intercept. Evaluating \(f(x)\) at \(x = 0\), 3 and 6:
\[f(0) = 5 - \dfrac{2}{3} (0) = 5\nonumber \]
\[f(3) = 5 - \dfrac{2}{3} (3) = 3\nonumber \]
\[f(6) = 5 - \dfrac{2}{3} (6) = 1\nonumber \]
These evaluations tell us that the points (0,5), (3,3), and (6,1) lie on the graph of the line. Plotting these points and drawing a line through them gives us the graph.
When using the initial value and rate of change to graph, we need to consider the graphical interpretation of these values. Remember the initial value of the function is the output when the input is zero, so in the equation \(f(x)=b+mx\), the graph includes the point \((0, b)\). On the graph, this is the vertical intercept – the point where the graph crosses the vertical axis.
For the rate of change, it is helpful to recall that we calculated this value as
\[m = \dfrac{change\ of\ output}{change\ of\ input}\nonumber\]
From a graph of a line, this tells us that if we divide the vertical difference, or rise, of the function outputs by the horizontal difference, or run, of the inputs, we will obtain the rate of change, also called slope of the line.
\[m=\dfrac{change\ of \ output}{change\ of\ input} = \dfrac{rise}{run}\nonumber \]
Notice that this ratio is the same regardless of which two points we use.
Graphically, in the equation\(f(x)=b+mx\),
\(b\) is the vertical intercept of the graph and tells us we can start our graph at (0, b)
\(m\) is the slope of the line and tells us how far to rise & run to get to the next point
Once we have at least 2 points, we can extend the graph of the line to the left and right.
Graph \(f(x)=5-\dfrac{2}{3} x\) using the vertical intercept and slope.
Solution
The vertical intercept of the function is (0, 5), giving us a point on the graph of the line.
The slope is \(-\dfrac{2}{3}\). This tells us that for every 3 units the graph “runs” in the horizontal, the vertical “rise” decreases by 2 units.
In graphing, we can use this by first plotting our vertical intercept on the graph, then using the slope to find a second point. From the initial value (0, 5) the slope tells us that if we move to the right 3, we will move down 2, moving us to the point (3, 3). We can continue this again to find a third point at (6, 1). Finally, extend the line to the left and right, containing these points.
Consider that the slope \(-\dfrac{2}{3}\) could also be written as \(\dfrac{2}{-3}\). Using \(\dfrac{2}{-3}\), find another point on the graph that has a negative \(x\) value.
- Answer
-
\((-3,7)\) found by starting at the vertical intercept, going up \(2\) units and \(3\) in the negative horizontal direction. You could have also answered, \((-6, 9)\) or \((-9, 11)\) etc …
Another option for graphing is to use transformations of the identity function\(f(x)=x\).
In the equation\(f(x)=mx\), the m is acting as the vertical stretch of the identity function. When \(m\) is negative, there is also a vertical reflection of the graph. Looking at some examples:
In\(f(x)=mx+b\), the b acts as the vertical shift, moving the graph up and down without affecting the slope of the line. Some examples:
Using Vertical Stretches or Compressions along with Vertical Shifts is another way to look at identifying different types of linear functions. Although this may not be the easiest way for you to graph this type of function, make sure you practice each method.
Graph \(f(x)=-3+\dfrac{1}{2} x\) using transformations.
Solution
The equation is the graph of the identity function vertically compressed by ½ and vertically shifted down 3.
Vertical Compression combined with Vertical shift
Notice how this nicely compares to the other method where the vertical intercept is found at (0, -3) and to get to another point we rise (go up vertically) by 1 unit and run (go horizontally) by 2 units to get to the next point (2, -2), and the next one (4, -1). In these three points (0, -3), (2, -2), and (4, -1), the output values change by +1, and the \(x\) values change by +2, corresponding with the slope \(m = 1/2\).
Match each equation with one of the lines in the graph below
\[f(x) = 2x + 3\nonumber \]
\[g(x) = 2x - 3\nonumber \]
\[(h(x) = -2x = 3\nonumber \]
\[j(x) = \dfrac{1}{2} x + 3\nonumber \]
Solution
Only one graph has a vertical intercept of - 3, so we can immediately match that graph with \(g(x)\).
For the three graphs with a vertical intercept at 3, only one has a negative slope, so we can match that line with \(h(x)\). Of the other two, the steeper line would have a larger slope, so we can match that graph with equation \(f(x)\), and the flatter line with the equation \(j(x)\).
In addition to understanding the basic behavior of a linear function (increasing or decreasing, recognizing the slope and vertical intercept), it is often helpful to know the horizontal intercept of the function – where it crosses the horizontal axis.
The horizontal intercept of the function is where the graph crosses the horizontal axis. If a function has a horizontal intercept, you can always find it by solving \(f(x) = 0\).
Find the horizontal intercept of \(f(x)=-3+\dfrac{1}{2} x\)
Solution
Setting the function equal to zero to find what input will put us on the horizontal axis,
\[\begin{array} {rcl} {0} &= & {-3 + \dfrac{1}{2}x} \\ {3} &= & {\dfrac{1}{2} x} \\ {x} &= & {6} \end{array}\nonumber\]
The graph crosses the horizontal axis at (6,0)
There are two special cases of lines: a horizontal line and a vertical line. In a horizontal line like the one graphed to the right, notice that between any two points, the change in the outputs is 0. In the slope equation, the numerator will be 0, resulting in a slope of 0. Using a slope of 0 in the \(f(x)=b+mx\), the equation simplifies to \(f(x)=b\).
Notice a horizontal line has a vertical intercept, but no horizontal intercept (unless it’s the line \(f(x) = 0\)).
In the case of a vertical line, notice that between any two points, the change in the inputs is zero. In the slope equation, the denominator will be zero, and you may recall that we cannot divide by the zero; the slope of a vertical line is undefined. You might also notice that a vertical line is not a function. To write the equation of vertical line, we simply write input=value, like \(x = b\).
Notice a vertical line has a horizontal intercept, but no vertical intercept (unless it’s the line \(x = 0\)).
Horizontal lines have equations of the form \(f(x)=b\)
Vertical lines have equations of the form \(x = a\)
Write an equation for the horizontal line graphed above.
Solution
This line would have equation \(f(x)=2\)
Write an equation for the vertical line graphed above.
Solution
This line would have equation \(x=2\)
Describe the function \(f(x)=6-3x\) in terms of transformations of the identity function and find its horizontal intercept.
- Answer
-
Vertically stretched by a factor of 3, Vertically flipped (flipped over the \(x\) axis),
Vertically shifted up by 6 units.
Horizontal intercept: \(6 - 3x = 0\) when \(x=2\).
Parallel and Perpendicular Lines
When two lines are graphed together, the lines will be parallel if they are increasing at the same rate – if the rates of change are the same. In this case, the graphs will never cross (unless they’re the same line).
Two lines are parallel if the slopes are equal (or, if both lines are vertical).
In other words, given two linear equations \(f(x)=b+m_{1} x\) and \(g(x)=b+m_{2} x\), the lines will be parallel if \(m_{1} =m_{2}\).
Find a line parallel to \(f(x)=6+3x\) that passes through the point (3, 0).
Solution
We know the line we’re looking for will have the same slope as the given line, \(m = 3\). Using this and the given point, we can solve for the new line’s vertical intercept:
\[g(x) = b + 3x\nonumber\] then at (3, 0),
\[0 = b + 3(3)\nonumber \]
\[b = -9\nonumber \]
The line we’re looking for is \(g(x)=-9+3x\).
If two lines are not parallel, one other interesting possibility is that the lines are perpendicular, which means the lines form a right angle (90 degree angle – a square corner) where they meet. In this case, the slopes when multiplied together will equal -1. Solving for one slope leads us to the definition:
Given two linear equations \(f(x)=b+m_{1} x\) and \(g(x)=b+m_{2} x\)
The lines will be perpendicular if \(m_{1} m_{2} =-1\), and so \(m_{2} =\dfrac{-1}{m_{1} }\)
We often say the slope of a perpendicular line is the “negative reciprocal” of the other line’s slope.
Find the slope of a line perpendicular to a line with:
a) a slope of 2. b) a slope of -4. c) a slope of \(\dfrac{2}{3}\).
Solution
If the original line had slope 2, the perpendicular line’s slope would be \(m_{2} =\dfrac{-1}{2}\)
If the original line had slope -4, the perpendicular line’s slope would be \(m_{2} =\dfrac{-1}{-4} =\dfrac{1}{4}\)
If the original line had slope \(\dfrac{2}{3}\), the perpendicular line’s slope would be \(m_2 = \dfrac{-1}{2/3} = \dfrac{-3}{2}\)
Find the equation of a line perpendicular to \(f(x)=6+3x\) and passing through the point (3, 0).
Solution
The original line has slope m = 3. The perpendicular line will have slope \(m=\dfrac{-1}{3}\). Using this and the given point, we can find the equation for the line.
\[g(x)=b-\dfrac{1}{3} x\nonumber \] then at (3, 0),
\[0 = b - \dfrac{1}{3} (3)\nonumber \]
\[b = 1\nonumber \]
The line we’re looking for is \(g(x)=1-\dfrac{1}{3} x\).
Given the line \(h(t)=-4+2t\), find an equation for the line passing through (0, 0) that is:
- parallel to h(t) .
- perpendicular to h(t).
- Answer
-
Parallel: \(f(t)=2t\)
Perpendicular: \(g(t)=-\dfrac{1}{2} t\)
A line passes through the points (-2, 6) and (4, 5). Find the equation of a perpendicular line that passes through the point (4, 5).
Solution
From the two given points on the reference line, we can calculate the slope of that line:
\[m_1 = \dfrac{5-6}{4 - (-2)} = \dfrac{-1}{6}\nonumber \]
The perpendicular line will have slope
\[m_2 = \dfrac{-1}{-1/6} = 6\nonumber \]
We can then solve for the vertical intercept that makes the line pass through the desired point:
\[g(x) = b + 6x\nonumber \] then at (4, 5)
\[5 = b + 6(4)\nonumber \]
\[b = -19\nonumber \]
Giving the line \(g(x)=-19+6x\)
Intersections of Lines
The graphs of two lines will intersect if they are not parallel. They will intersect at the point that satisfies both equations. To find this point when the equations are given as functions, we can solve for an input value so that \(f(x)=g(x)\). In other words, we can set the formulas for the lines equal, and solve for the input that satisfies the equation.
Find the intersection of the lines \(h(t)=3t-4\) and \(j(t)=5-t\).
Solution
Setting \(h(t)=j(t)\),
\[\begin{array} {rcl} {3t - 4} &= & {5 - t} \\ {4t} &= & {9} \\ {t} &= & {\dfrac{9}{4}} \end{array}\nonumber \]
This tells us the lines intersect when the input is \(\dfrac{9}{4}\).
We can then find the output value of the intersection point by evaluating either function at this input
\[j(\dfrac{9}{4} )=5-\dfrac{9}{4} =\dfrac{11}{4}\nonumber \]
These lines intersect at the point \((\dfrac{9}{4} ,\dfrac{11}{4} )\). Looking at the graph, this result seems reasonable.
Two parallel lines can also intersect if they happen to be the same line. In that case, they intersect at every point on the lines.
Look at the graph in example 13 above and answer the following for the function \(h(t)\):
a. Vertical intercept coordinates
b. Horizontal intercepts coordinates
c. Slope
d. Is \(j(t)\) parallel or perpendicular to \(h(t)\) (or neither)
e. Is h(t) an Increasing or Decreasing function (or neither)
f. Write a transformation description from the identity toolkit function \(f(x) = x\)
- Answer
-
4. Given \(h(t)=3t-4\)
a. (0,-4)
b. \((\dfrac{4}{3} ,0)\)
c. Slope 3
d. Neither parallel nor perpendicular
e. Increasing function
f. Given the identity function, vertically stretch by 3 and shift down 4 units.
Finding the intersection allows us to answer other questions as well, such as discovering when one function is larger than another.
Using the functions from the previous example, for what values of t is \(h(t) > j(t)\).
Solution
To answer this question, it is helpful first to know where the functions are equal, since that is the point where \(h(t)\) could switch from being greater to smaller than \(j(t)\) or vice-versa. From the previous example, we know the functions are equal at \(t=\dfrac{9}{4}\).
By examining the graph, we can see that \(h(t)\), the function with positive slope, is going to be larger than the other function to the right of the intersection. So \(h(t) > j(t)\) when \(t > \dfrac{9}{4}\)
Important Topics of this Section
- Methods for graphing linear functions
- Another name for slope = rise/run
- Horizontal intercepts (a,0)
- Horizontal lines
- Vertical lines
- Parallel lines
- Perpendicular lines
- Intersecting lines


27.5A: Fourth Week of Development
The fourth week of gestation is characterized by the flexion of the superior portion of the neural tube to create the mesencephalon.
- Describe the fourth week of embryonic development
Key Points
- Neural tube flexion patterns determine neural development, including the positioning and differentiation of the prosencephalon and rhombencephalon, as well as the optical vesicle.
- Important changes occur to the embryonic heart as well, including development of the pharyngeal arches.
- At the end of the fourth week, the yolk sac presents the appearance of a small pear-shaped vesicle (the umbilical vesicle) that opens into the digestive tube by a long, narrow tube—the vitelline duct.
Key Terms
- mesencephalon : A part of the brain located rostral to the pons and caudal to the thalamus and the basal ganglia, composed of the tectum (dorsal portion) and the tegmentum (ventral portion).
- mandibular arch : The first pharyngeal arch, also called the mandibular arch, is the first of six aortic arches that develops in fetal life during the fourth week of development.
- optical vesicle : The eyes begin to develop as a pair of diverticula from the lateral aspects of the forebrain. These diverticula make their appearance before the closure of the anterior end of the neural tube; after the closure of the tube they are known as the optic vesicles.
Placentation
Trophoblast cells surrounding the embryonic cells proliferate and invade deeper into the uterine lining. They will eventually form the placenta and embryonic membranes. At the end of the fourth week the yolk sac presents the appearance of a small pear-shaped vesicle (the umbilical vesicle) opening into the digestive tube by a long narrow tube, the vitelline duct.
The chorion undergoes rapid proliferation and forms numerous processes. The chorionic villi, which invade and destroy the uterine decidua and at the same time absorb from it nutritive materials for the growth of the embryo. Until about the end of the second month of pregnancy the villi cover the entire chorion, and are almost uniform in size, but after this they develop unequally.
Mesencephalon Development
Late in the fourth week of gestation, the superior part of the neural tube flexes at the level of the future midbrain, the mesencephalon. Superior to the mesencephalon is the prosencephalon (future forebrain) and inferior to it is the rhombencephalon (future hindbrain). The optical vesicle (which will eventually become the optic nerve, retina, and iris) forms at the basal plate of the prosencephalon.
Embryo brain at four weeks : At four weeks the embryo’s brain can be differentiated into the proscephalon, mesencephalon, and rhombencephalon. A white circle represents the area of the optical vesicle.
Pharyngeal Arch Development
The embryonic heart attains functionality and starts beating at 22 days after conception (about five weeks after the last menstrual period). It can sometimes be seen as flickering in the embryonic chest by an ultrasound performed during the fourth week after conception.
During the fourth week of development, the first pharyngeal arch, also called the mandibular arch, is the first of six pharyngeal arches that begins to develop. It is located between the stomodeum and the first pharyngeal groove.
Developing fetus : A schematic of a developing fetus with the first, second, and third arches labeled.
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11.6: How Genes Are Regulated
By the end of this section, you will be able to do the following:
- Discuss why every cell does not express all of its genes
- Describe how prokaryotic gene expression occurs at the transcriptional level
- Understand that eukaryotic gene expression occurs at the epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels
For a cell to function properly, necessary proteins must be synthesized at the proper time. All organisms and cells control or regulate the transcription and translation of their DNA into protein. The process of turning on a gene to produce RNA and protein is called gene expression. Whether in a simple unicellular organism or in a complex multicellular organism, each cell controls when and how its genes are expressed. For this to occur, there must be a mechanism to control when a gene is expressed to make RNA and protein, how much of the protein is made, and when it is time to stop making that protein because it is no longer needed.
Cells in multicellular organisms are specialized; cells in different tissues look very different and perform different functions. For example, a muscle cell is very different from a liver cell, which is very different from a skin cell. These differences are a consequence of the expression of different sets of genes in each of these cells. All cells have certain basic functions they must perform for themselves, such as converting the energy in sugar molecules into energy in ATP. Each cell also has many genes that are not expressed, and expresses many that are not expressed by other cells, such that it can carry out its specialized functions. In addition, cells will turn on or off certain genes at different times in response to changes in the environment or at different times during the development of the organism. Unicellular organisms, both eukaryotic and prokaryotic, also turn on and off genes in response to the demands of their environment so that they can respond to special conditions.
The control of gene expression is extremely complex. Malfunctions in this process are detrimental to the cell and can lead to the development of many diseases, including cancer.
Prokaryotic versus Eukaryotic Gene Expression
To understand how gene expression is regulated, we must first understand how a gene becomes a functional protein in a cell. The process occurs in both prokaryotic and eukaryotic cells, just in slightly different fashions.
Because prokaryotic organisms lack a cell nucleus, the processes of transcription and translation occur almost simultaneously. When the protein is no longer needed, transcription stops. As a result, the primary method to control what type and how much protein is expressed in a prokaryotic cell is through the regulation of DNA transcription into RNA. All the subsequent steps happen automatically. When more protein is required, more transcription occurs. Therefore, in prokaryotic cells, the control of gene expression is almost entirely at the transcriptional level.
The first example of such control was discovered using E . coli in the 1950s and 1960s by French researchers and is called the lac operon. The lac operon is a stretch of DNA with three adjacent genes that code for proteins that participate in the absorption and metabolism of lactose, a food source for E . coli . When lactose is not present in the bacterium’s environment, the lac genes are transcribed in small amounts. When lactose is present, the genes are transcribed and the bacterium is able to use the lactose as a food source. The operon also contains a promoter sequence to which the RNA polymerase binds to begin transcription; between the promoter and the three genes is a region called the operator. When there is no lactose present, a protein known as a repressor binds to the operator and prevents RNA polymerase from binding to the promoter, except in rare cases. Thus very little of the protein products of the three genes is made. When lactose is present, an end product of lactose metabolism binds to the repressor protein and prevents it from binding to the operator. This allows RNA polymerase to bind to the promoter and freely transcribe the three genes, allowing the organism to metabolize the lactose.
Eukaryotic cells, in contrast, have intracellular organelles and are much more complex. Recall that in eukaryotic cells, the DNA is contained inside the cell’s nucleus and it is transcribed into mRNA there. The newly synthesized mRNA is then transported out of the nucleus into the cytoplasm, where ribosomes translate the mRNA into protein. The processes of transcription and translation are physically separated by the nuclear membrane; transcription occurs only within the nucleus, and translation only occurs outside the nucleus in the cytoplasm. The regulation of gene expression can occur at all stages of the process (Figure \(\PageIndex{1}\)). Regulation may occur when the DNA is uncoiled and loosened from nucleosomes to bind transcription factors (epigenetic level), when the RNA is transcribed (transcriptional level), when RNA is processed and exported to the cytoplasm after it is transcribed (post-transcriptional level), when the RNA is translated into protein (translational level), or after the protein has been made (post-translational level).
The differences in the regulation of gene expression between prokaryotes and eukaryotes are summarized in Table \(\PageIndex{1}\).
| Prokaryotic organisms | Eukaryotic organisms |
|---|---|
| Lack nucleus | Contain nucleus |
| RNA transcription and protein translation occur almost simultaneously |
|
| Gene expression is regulated primarily at the transcriptional level | Gene expression is regulated at many levels (epigenetic, transcriptional, post-transcriptional, translational, and post-translational) |
EVOLUTION IN ACTION: Alternative RNA Splicing
In the 1970s, genes were first observed that exhibited alternative RNA splicing. Alternative RNA splicing is a mechanism that allows different protein products to be produced from one gene when different combinations of introns (and sometimes exons) are removed from the transcript (Figure \(\PageIndex{2}\)). This alternative splicing can be haphazard, but more often it is controlled and acts as a mechanism of gene regulation, with the frequency of different splicing alternatives controlled by the cell as a way to control the production of different protein products in different cells, or at different stages of development. Alternative splicing is now understood to be a common mechanism of gene regulation in eukaryotes; according to one estimate, 70% of genes in humans are expressed as multiple proteins through alternative splicing.
How could alternative splicing evolve? Introns have a beginning and ending recognition sequence, and it is easy to imagine the failure of the splicing mechanism to identify the end of an intron and find the end of the next intron, thus removing two introns and the intervening exon. In fact, there are mechanisms in place to prevent such exon skipping, but mutations are likely to lead to their failure. Such “mistakes” would more than likely produce a nonfunctional protein. Indeed, the cause of many genetic diseases is alternative splicing rather than mutations in a sequence. However, alternative splicing would create a protein variant without the loss of the original protein, opening up possibilities for adaptation of the new variant to new functions. Gene duplication has played an important role in the evolution of new functions in a similar way—by providing genes that may evolve without eliminating the original functional protein.
Contributors and Attributions
Remixed and/or curated from the following works:
Fowler, S., Roush, R., & Wise, J. (2013). 9.5 How Genes Are Regulated . In Concepts of Biology . OpenStax (CC BY 4.0; Access for free at https://openstax.org/books/concepts-biology/pages/1-introduction ).


31.5: Refugees
By the end of this section, you should be able to:
- Differentiate between a refugee and an asylum seeker.
- Describe common health conditions affecting population health in refugee camps.
- Explain the unique health challenges for refugees and asylum seekers.
- Discuss why promoting the health of refugees is a matter of social justice.
- Explain the nurse’s role in addressing the refugee crisis to uphold nursing’s mission to society.
Refugee and asylum seeker both refer to people who have left their homes, and they are often used interchangeably. Although the two groups flee their homes for similar reasons, they use different means to reach the United States. The different designations have separate legal statuses with consequent legal obligations and protections.
According to the 1951 Convention Relating to the Status of Refugees, a refugee is “a person who, as a result of a well-founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group, or political opinion” has crossed an international border and cannot return to their home (United Nations [UN], 2023a). Recently, more people have been forced to flee their homes than at any time since World War II, with about 110 million individuals displaced worldwide (International Rescue Committee, 2023; UN Higher Commission for Refugees [UNHCR], 2023b). Child refugees face numerous risks and dangers, including disease, malnutrition, violence, labor exploitation, and trafficking.
The UN Higher Commission for Refugees (UNHCR, 2023b) defines forced displacement “as a result of persecution, conflict, generalized violence or human rights violations” and a stateless person (UNHCR, 2023a) as someone who is “not considered as a national by any state under the operation of its law.” Some stateless people are also refugees. However, not all refugees are stateless, and many people who are stateless have never crossed an international border (U.S. Department of State, n.d.).
Asylum is a form of legal protection that prevents individuals from being deported to a country where they might experience harm and may legally remain. An asylum seeker is someone who has fled persecution and serious human rights violations in their home country but who has not yet been legally recognized as a refugee or received a decision on their asylum claim. Seeking asylum is a human right (Amnesty International, 2023), and individuals can apply for asylum either at another country’s border or from within the country where they would like to resettle. An individual cannot seek asylum in the United States from their native country—individuals may file for asylum only if they are in the United States or at a port of entry.
International law protects refugees. Under the 1951 Refugee Convention (and its 1967 Protocol), refugees cannot be returned to their home country after fleeing and seeking asylum in another country. Before leaving their geographical home of legal affiliation (i.e., where they would hold a passport of issuance), they must apply for refugee status through the United Nations High Commission for Refugees (UNHCR; 2023c) and then be selected for resettlement. Refugees do not get to choose the country where they will be resettled; they are more likely to be resettled in the United States if they already have family members living there. Refugees are thoroughly vetted, with multiple background checks and medical screenings. Once they have passed all checks and are approved, they are flown to the United States, where a local resettlement agency helps them during a transition period when they first arrive. Table 31.3 presents definitions of the terms used to describe these populations.
| Term | Definition |
|---|---|
| Asylum seeker | Someone whose request for sanctuary has yet to be processed. Every year, around one million people seek asylum. |
| Immigrant | A person living in a country other than that of their birth. |
| Migrant | An umbrella term, not defined under international law, reflecting the common lay understanding of a person who moves away from their place of usual residence, whether within a country or across an international border, temporarily or permanently. |
| Refugee | Someone forced to flee their home because of war, violence, or persecution, often without warning. They cannot return home unless and until conditions there are safe for them again. |
Common Conditions Affecting Health in Refugee Camps
Many who flee their homes or are forcibly displaced find themselves in a refugee camp , a temporary settlement built to accommodate displaced people who have fled their home country; however, camps are also made for internally displaced people (Figure 31.7). Usually, refugees seek asylum after escaping war in their home countries, but some camps also house environmental and economic migrants. Refugee camps with over a hundred thousand people are common; however, the average-sized camp houses approximately 11,000 people (Daynes, 2016; USA for UNHCR, 2023). The Kutupalong-Balukhali refugee settlement in Bangladesh includes over 800,000 refugees, over half of them children, making it one of the largest such settlements in the world (USA for UNHCR, 2023).
Refugee camps are usually built and run by a government, the UN, international organizations (such as the International Committee of the Red Cross), or nongovernmental organizations (NGOs). Refugee camps generally develop impromptu to provide people with protection and assistance. Shelters include rental units, prefabricated containers, tents, plastic sheeting, and other materials based on available supplies (UNHCR, n.d.-a; n.d.-b). Space in the camps is often tight, so shelters are often crowded together. It is common for several families to live together in the same dwelling.
The quality and quantity of sanitation facilities vary among camps. While some may have communal toilet facilities and running water, others may rely on pit latrines dug by residents. Few or no sanitary facilities may be accessible for people with disabilities (CARE Staff, 2020). Poor drainage, seasonal flooding, and inadequate cleaning increase infectious disease risk. According to the UNHCR Emergency Handbook , each person should be allocated 15 liters (about 4 gallons) of water per day in an emergency situation and 20 liters (about 5.25 gallons) in a nonemergency situation for personal and domestic needs (UNHCR, n.d.-a). However, the UNHCR estimates that over half of existing camps lack the water to meet these guidelines (The Borgen Project, 2020).
Unique Health Challenges
Refugees and asylum seekers can have complex health needs. Overcrowding, poor water and sanitation conditions, lack of vaccinations, delayed diagnosis, and reduced access to treatment can increase the occurrence, severity, and case fatality of infectious diseases (Altare et al., 2019). For example, viral hepatitis A, B, and C (CDC, 2020; Taha et al., 2023), measles, diarrheal diseases, acute respiratory infection, and malaria account for 60 to 80 percent of all reported causes of death among refugees (Johns Hopkins Bloomberg School of Public Health, 2018). Cholera outbreaks may also occur because camps have ideal conditions for its spread: inadequate water treatment, poor sanitation, and inadequate hygiene (Bonyan Organization, 2023). For children, key priority infectious diseases among refugee populations include tuberculosis, hepatitis B, and vaccine-preventable and parasitic diseases (Shetty, 2019). COVID-19 took a devastating toll on refugee resettlement. In addition to exposure to infectious diseases, individuals may have preexisting or poorly controlled chronic conditions, such as diabetes, cardiovascular diseases, respiratory conditions, and cancer. Many have psychiatric illnesses like post-traumatic stress disorder and depression (Abbas, et al., 2018) as well as maternity care needs.
Holistic and person-centered care is essential to support resilience and help refugees and asylum seekers adapt to life in the United States. When a nurse treats a refugee or asylum seeker, they should screen for infectious diseases that are common in countries where these clients have spent time. The nurse may also identify symptoms of communicable diseases when clients present with other routine issues. In some countries, screening for infectious diseases, such as HIV and hepatitis, may not be easily accessible, or people may not seek testing due to fear of stigma or lack of treatment options. Nurses should discuss the possibility of receiving a positive result in advance with clients from countries with high rates of certain diseases. They should find out what vaccinations refugees and asylum seekers have received and offer missing vaccinations to children and adults based on the latest national immunization schedule. As with all clients, nurses should inform refugees and asylum seekers about any testing, treatment, or vaccinations offered to them. This may require extra care in explaining their rights to confidentiality. For example, a nurse may need to reassure a client that a positive test result will not negatively affect asylum applications. Some clients may need additional health education in an appropriate language to understand their options, which may require an interpreter, or it may be appropriate to give the client written information in their language to take away, depending on their literacy level. Specialist client support organizations may also be able to assist with educating and informing clients about their rights and health care options.
Women who have experienced female genital mutilation (FGM), and their female children if they are considered to be at risk of FGM, may require additional support. FGM can cause ongoing physical and mental health issues, including complications during pregnancy and childbirth, which should be planned for. It may also deter women from being screened for cervical cancer (United Nations Population Fund, 2022).
Although refugees and asylums seekers do not display mental health problems frequently (Gov.UK, 2017; Hynie, 2018), they can be at increased risk, particularly if they have experienced violence and trauma, including exploitation, torture, or sexual and gender-based violence. Issues can range from low to moderate levels of anxiety and depression to more severe mental disorders. People from different cultural backgrounds can have different conceptions and experiences of mental illness. For example, clients may complain about nonspecific pain, frequent headaches, and stomachaches rather than emotional distress. In such cases, the nurse should sensitively investigate their history, as well as current circumstances, to establish whether such complaints may be an expression of mental health or other social issues. This approach can help minimize unnecessary referrals for investigations and medication prescribing. It can be helpful to consider dialect, culture, gender, and sexual orientation when selecting a language interpreter. It may also be beneficial to link clients with support organizations with expertise in supporting refugees and asylum seekers.
Providing TIC for people who have experienced violence or persecution—particularly torture—can be challenging. Refugees and asylum seekers are also at risk of exploitation, trafficking, and modern slavery. According to the British Medical Association, “recent estimates suggest that on average 44 percent of asylum seekers have experienced torture, although this can vary significantly by country” (BMA, 2023). This can often involve experiences of mental, physical, and sexual violence. They may be unable to discuss their health problems openly or fear examination. They may also have difficulty trusting people in positions of authority, including doctors. Experiences of torture and other violence can cause deep-rooted feelings of shame, humiliation, and guilt, and many clients may be reluctant to disclose to a relative stranger. Nurses should respond compassionately and sensitively and be aware that building a relationship of trust and support to facilitate disclosure can take some time. If clients are willing to talk about what happened to them, the situation described can be disturbing for the nurse and the client. This is a time when the nurse can maximize their use of the TIC steps presented earlier in the chapter.
Promoting Social Justice
As a term, “social justice” must consider four principles: access, human rights, participation, and equity (Soken-Huberty, 2023; WHO, 2022b):
- Access: Countries that have signed the 1951 Convention are obliged to protect refugees on their territory and treat them according to internationally recognized standards. Subsequently, protecting refugees is the primary responsibility of states.
- Human rights : Refugees have human rights, the inalienable rights to which a person is entitled merely for being human. Refugees must respect the laws and regulations of the United States. Refugees should receive at least the same rights and basic help as any other foreigner who is a legal resident, including freedom of thought and movement and freedom from torture and degrading treatment.
- Participation: Refugees bring productivity to host countries, where they are integrated across communities. They enrich those communities, helping to nurture understanding and appreciation for social diversity.
- Equity : To fulfill physical protection minimum standards, refugees need to be provided with adequate food, sanitation, hygienic products, and any nonfood items that are needed in a specific context or emergency.
Nurses have a professional and ethical responsibility to advocate for social justice (ANA, 2015). Refugees are one of the most vulnerable populations in the United States, and they interact with nurses at all levels of the health care system. As nurses become increasingly educated and skilled in cultural competence, they can make the transition to immigration less chaotic and subsequently enhance well-being and promote healthy lifestyles.
The Nurse’s Role in Addressing the Refugee Crisis
It is a human right to seek asylum from persecution or safety from war or disaster, and in doing so, people should not be subjected to cruel, inhumane, or degrading treatment or circumstances. Nurses need to foster a healthy and adaptive environment in which people can thrive despite personal, political, emotional, physical, or social adversity. Nursing care is indispensable for the easing of human distress and for the promotion of comfort and coping. Nurses are essential in advocating for policies that will enhance immigrants’ access to health care and mental health services and address barriers irrespective of their status as migrants, refugees, or asylum seekers (Desmyth et al., 2021). At the macro level, based on the New York Declaration for Refugees and Migrants , signed by the United Nations (2016b), it is the obligation of a state not to hinder refugees seeking to enter it, nor to return them forcibly to the country they have fled (the principle of nonrefoulement), which is grounded in the natural duty not to harm the innocent.
At the more micro level, nurses need to understand the legal and systemic difference between an individual seeking asylum for fear of persecution and someone who has been granted refugee status and offered humanitarian protection. While health care entitlements between these groups remain inconsistent, the principle of access to equitable health care as a fundamental human right must be upheld (Desmyth et al., 2021). The codes of ethics of the ANA and the International Council of Nurses (ICN) mandate that all nurses work to advocate for social justice (ANA, 2015; ICN, 2012). Thus, nurses are expected to apply these ethical principles in practice.
Nursing care and advocacy must be in the context of justice and equity, which requires ongoing awareness of and involvement with the resources in communities. Nurses can collaborate with organizations to acknowledge and dismantle racism and sexism and foster human rights. Instead of giving a “voice” to migrants and refugees, nurses provide opportunities for them to tell their own stories as well as to identify their own health needs and the best ways to address those needs (Commodore-Mensah et al., 2021).
A focal point for the Healthy People 2030 initiative is Social Cohesion . Social cohesion has significant ramifications for health. For example, one study examined the link between four measures of social capital (perceived fairness, perceived helpfulness, group membership, and trust), income inequality, and mortality. The authors found that all four measures of social capital were associated with mortality. They also found that the relationship between income inequality and mortality may be partially explained by reductions in social capital as income inequality increases. Collective efficacy, an aspect of social capital and social cohesion, is grounded on mutual trust and describes a community’s ability to create change and exercise informal social control (i.e., influence behavior through social norms). Collective efficacy is associated with better self-rated health, lower rates of neighborhood violence, and better access to health-enhancing resources like medical care, healthy food options, and places to exercise. Social institutions like religion and the family are common sources of social capital and social control as well as social networks and social support.


3.1: Dealing with Test Anxiety- Managing Your Stress for Success
Learning Objectives
At the end of this section, the learning will:
- Describe how to manage anxiety related to exams.
- Evaluate the level of personal test anxiety.
- Identify where to locate resources to help with test anxiety.
The Dos and Don’ts of Managing Anxiety Related to Exams
The stress brought on by a major exam in a course can be extreme enough that it impairs the clear thinking needed for optimal performance. Consider the Dos and Don’ts lists below for managing anxiety related to exams.
DO…
- Do prepare for an exam using the “Five-Day Study Plan” in Chapter 3.3. Students who feel prepared will have less anxiety overall.

- Do plan to reward yourself with something relaxing or fun after the exam. Think about that when stressful thoughts may occur.
- Do relax the last hour before the exam to reduce tension and stressful thoughts.
- Do eat a moderate breakfast that includes both protein and healthy carbohydrates.
- Do periodically conduct checks on the tension in certain areas of your body and try to relax those areas. Breathing deeply and engaging in some positive imagery can also reduce tension quickly during an exam.
- Do survey the entire exam and plan carefully.
- Do ask questions of your professor if you are unsure about what to do on a particular question.
DON’T…
- Don’t cram for an exam. Underprepared students naturally have something to worry about.
- Don’t let negative thoughts or worrying get in the way of clear thinking. If you catch yourself worrying about what you do not know, stop yourself and replace it with positive affirmations and what you do know.
- Don’t spend time with classmates who might confuse you or generate stress about the exam on the day of the exam.
- Don’t stay up late the night before the exam. A good night’s sleep will improve your mental state and promote clearer thinking.
- Don’t drink a lot of caffeine before the exam. Arousal from caffeine can add to stress and make you jumpy.
- Don’t show up late for an exam. Feeling rushed to finish adds to the stress.
- Don’t panic if you “go blank” on a question. Go answer other questions and come back to it later. If all else fails, guess or write down what you do know.
- Don’t resort to looking at anyone else’s paper if you are unsure of your performance. Maintaining your integrity is far more important than the results of this exam.
If you feel that you are unable to manage your stress, please utilize the resources through the university listed in the appendix of this book. You don’t have to do this alone!
activity 4.1 – Test anxiety ASsessment
Test Anxiety Assessment
Do you experience test anxiety?
Rate yourself on these items.
| Usually | Sometimes | Not usually | |
| I am so nervous on tests that I don’t do my best, even when I have studied well and am prepared. | |||
| My stomach gets tight and upset before or during a test | |||
| My hands get cold and sweaty during a test. | |||
| I get headaches before or during a test. | |||
| I have trouble sleeping the night before a test. | |||
| I find my mind racing or becoming dull and “muddy” so that I can’t think clearly while taking a test. | |||
| During a test, I forget material I have studied and learned, only to remember it again after the test is over. | |||
| I “over-analyze” questions, see too many possibilities, choose complex answers, and overlook the simpler, correct answers. | |||
| I make careless errors on a test. |
The more checks you put in the “usually” or “sometimes” columns, the greater the likelihood that you may be experiencing test anxiety. This is a common issue, and there is help available. Please refer to the appendix for resources available.


10.2: Respiratory Basic Concepts
The main function of our respiratory system is to provide the body with a constant supply of oxygen and to remove carbon dioxide. To achieve these functions, muscles and structures of the thorax create the mechanical movement of air into and out of the lungs called ventilation . Respiration includes ventilation and gas exchange at the alveolar level where blood is oxygenated and carbon dioxide is removed. When completing a respiratory assessment, it is important for the nurse to understand the external and internal structures involved with respiration and ventilation. See Figure \(\PageIndex{1}\) [1] for an illustration of the upper and lower respiratory system structures. Notice the lobular division of the lung structures and the bronchial tree.
For more information on basic oxygenation concepts, visit the “ Oxygen Therapy ” chapter of this book.
For more information about applying the nursing process to patients experiencing decreased oxygenation, visit the “ Oxygenation ” chapter in Open RN Nursing Fundamentals .
For a detailed review of the respiratory system, common respiratory disorders, and related medications, visit the “ Respiratory ” chapter of the Open RN Nursing Pharmacology textbook. Specific sections of this chapter include the following:
Respiratory System Anatomy [2]
Respiratory System: Breathing Mechanics [3]
- “Respiratory_system_complete_en.png” by British Columbia Institute of Technology is licensed under CC BY 4.0 . Access for free at https://opentextbc.ca/clinicalskills/chapter/2-5-focussed-respiratory-assessment/ ↵
- Forciea, B. (2015, May 13). Respiratory system anatomy (v2.0) . [Video]. YouTube. All rights reserved. Video used with permission. https://youtu.be/aqTwrdMS6CE ↵
- Forciea, B. (2015, May 12). Anatomy and physiology: Respiratory system: Breathing mechanics (v2.0) . [Video]. YouTube. All rights reserved. Video used with permission. https://youtu.be/X-J5Xgg3l6s ↵


11.3: Production and Properties of Electromagnetic Waves
Learning Objectives
- Describe the electric and magnetic waves as they move out from a source, such as an AC generator.
- Describe the momentum carried by electromagnetic waves and its relationship to radiation pressure.
We can get a good understanding of electromagnetic waves (EM) by considering how they are produced. Whenever a current varies, associated electric and magnetic fields vary, moving out from the source like waves. Perhaps the easiest situation to visualize is a varying current in a long straight wire, produced by an AC generator at its center, as illustrated in Figure \(\PageIndex{1}\).
The electric field (\(\mathbf{E}\)) shown surrounding the wire is produced by the charge distribution on the wire. Both the \(\mathbf{E}\) and the charge distribution vary as the current changes. The changing field propagates outward at the speed of light.
There is an associated magnetic field (\(\mathbf{B}\)) which propagates outward as well (see Figure \(\PageIndex{2}\)). The electric and magnetic fields are closely related and propagate as an electromagnetic wave. This is what happens in broadcast antennae such as those in radio and TV stations.
Closer examination of the one complete cycle shown in Figure \(\PageIndex{1}\) reveals the periodic nature of the generator-driven charges oscillating up and down in the antenna and the electric field produced. At time \(t=0\), there is the maximum separation of charge, with negative charges at the top and positive charges at the bottom, producing the maximum magnitude of the electric field (or \(E\)-field) in the upward direction. One-fourth of a cycle later, there is no charge separation and the field next to the antenna is zero, while the maximum \(E\)-field has moved away at speed \(c\).
As the process continues, the charge separation reverses and the field reaches its maximum downward value, returns to zero, and rises to its maximum upward value at the end of one complete cycle. The outgoing wave has an amplitude proportional to the maximum separation of charge. Its wavelength (\(\lambda\)) is proportional to the period of the oscillation and, hence, is smaller for short periods or high frequencies. (As usual, wavelength and frequency (\(f\)) are inversely proportional.)
Electric and Magnetic Waves: Moving Together
Following Ampere’s law, current in the antenna produces a magnetic field, as shown in Figure \(\PageIndex{2}\). The relationship between \(\mathbf{E}\) and \(\mathbf{B}\) is shown at one instant in Figure \(\PageIndex{2}\)(a). As the current varies, the magnetic field varies in magnitude and direction.
The magnetic field lines also propagate away from the antenna at the speed of light, forming the other part of the electromagnetic wave, as seen in Figure \(\PageIndex{2}\)(b). The magnetic part of the wave has the same period and wavelength as the electric part, since they are both produced by the same movement and separation of charges in the antenna.
The electric and magnetic waves are shown together at one instant in time in Figure \(\PageIndex{3}\). The electric and magnetic fields produced by a long straight wire antenna are exactly in phase. Note that they are perpendicular to one another and to the direction of propagation, making this a transverse wave .
Electromagnetic waves generally propagate out from a source in all directions, sometimes forming a complex radiation pattern. A linear antenna like this one will not radiate parallel to its length, for example. The wave is shown in one direction from the antenna in Figure \(\PageIndex{3}\) to illustrate its basic characteristics.
Instead of the AC generator, the antenna can also be driven by an AC circuit. In fact, charges radiate whenever they are accelerated. But while a current in a circuit needs a complete path, an antenna has a varying charge distribution forming a standing wave , driven by the AC. The dimensions of the antenna are critical for determining the frequency of the radiated electromagnetic waves. This is a resonant phenomenon and when we tune radios or TV, we vary electrical properties to achieve appropriate resonant conditions in the antenna.
Receiving Electromagnetic Waves
Electromagnetic waves carry energy away from their source, similar to a sound wave carrying energy away from a standing wave on a guitar string. An antenna for receiving EM signals works in reverse. And like antennas that produce EM waves, receiver antennas are specially designed to resonate at particular frequencies.
An incoming electromagnetic wave accelerates electrons in the antenna, setting up a standing wave. If the radio or TV is switched on, electrical components pick up and amplify the signal formed by the accelerating electrons. The signal is then converted to audio and/or video format. Sometimes big receiver dishes are used to focus the signal onto an antenna.
In fact, charges radiate whenever they are accelerated. When designing circuits, we often assume that energy does not quickly escape AC circuits, and mostly this is true. A broadcast antenna is specially designed to enhance the rate of electromagnetic radiation, and shielding is necessary to keep the radiation close to zero. Some familiar phenomena are based on the production of electromagnetic waves by varying currents. Your microwave oven, for example, sends electromagnetic waves, called microwaves, from a concealed antenna that has an oscillating current imposed on it.
Momentum Carried by Electromagnetic Waves
As electromagnetic waves are received, as described above, the forces exerted on the charged particles (see [link] 1 for diagrams) do work on the particles and increase its energy. The energy that sunlight carries is a familiar part of every warm sunny day. A much less familiar feature of electromagnetic radiation is the extremely weak pressure that electromagnetic radiation produces by exerting a force in the direction of the wave. This force occurs because electromagnetic waves contain and transport momentum.
To understand the direction of the force for a very specific case, consider a plane electromagnetic wave incident on a metal. The electrons in the metal move with the velocity \(\boldsymbol{v}\) that is proportional to the force on it due to applied electric force (in opposite direction to \(\boldsymbol{E}\) because electron is negatively charged). There are other, frictional forces in the metal that make this motion happen (this is the origin of Ohm's law in electric circuits). Note that there is also a magnetic field in the electromagnetic wave ( Figure \(\PageIndex{4}\)). Using the right-hand rule (magnetic force is \(\boldsymbol{F}=q(\boldsymbol{v} \times \boldsymbol{B})\)), we can get the direction of force on the electron (remember that electron is negatively charged), which is shown in Figure \(\PageIndex{4}\). This force is in the same direction as the direction of wave propagation, and it represents a transfer of momentum carried by the electromagnetic wave from the wave to the electron. This momentum is directly proportional to the energy carried by the electromagnetic wave and is given by,
\[p=\frac{E}{c}, \nonumber \]
where \(p\) is the magnitude of momentum of electromagnetic wave, \(E\) is the energy of electromagnetic wave, and \(c\) is the speed of light.
Maxwell predicted that an electromagnetic wave carries momentum. An object absorbing an electromagnetic wave would experience a force in the direction of propagation of the wave. The force corresponds to radiation pressure exerted on the object by the wave. The force would be twice as great if the radiation were reflected rather than absorbed, because the change in the momentum of electromagnetic wave itself is twice as great (and we enforce momentum conservation of the system as a whole).
Maxwell’s prediction was confirmed in 1903 by Nichols and Hull by precisely measuring radiation pressures with a torsion balance. The schematic arrangement is shown in Figure \(\PageIndex{5}\). The mirrors suspended from a fiber were housed inside a glass container. Nichols and Hull were able to obtain a small measurable deflection of the mirrors from shining light on one of them. From the measured deflection, they could calculate the unbalanced force on the mirror, and obtained agreement with the predicted value of the force.
Radiation pressure plays a role in explaining many observed astronomical phenomena, including the appearance of comets . Comets are basically chunks of icy material in which frozen gases and particles of rock and dust are embedded. When a comet approaches the Sun, it warms up and its surface begins to evaporate. The coma of the comet is the hazy area around it from the gases and dust. Some of the gases and dust form tails when they leave the comet. Notice in Figure \(\PageIndex{6}\) that a comet has two tails. The ion tail (or gas tail in Figure \(\PageIndex{6}\)) is composed mainly of ionized gases. These ions interact electromagnetically with the solar wind, which is a continuous stream of charged particles emitted by the Sun. The force of the solar wind on the ionized gases is strong enough that the ion tail almost always points directly away from the Sun. The second tail is composed of dust particles. Because the dust tail is electrically neutral, it does not interact with the solar wind. However, this tail is affected by the radiation pressure produced by the light from the Sun. Although quite small, this pressure is strong enough to cause the dust tail to be displaced from the path of the comet.
After Maxwell showed that light carried momentum as well as energy, a novel idea eventually emerged, initially only as science fiction. Perhaps a spacecraft with a large reflecting solar sail could use radiation pressure for propulsion. Such a vehicle would not have to carry fuel. It would experience a constant but small force from solar radiation, instead of the short bursts from rocket propulsion. It would accelerate slowly, but by being accelerated continuously, it would eventually reach great speeds. A spacecraft with small total mass and a sail with a large area would be necessary to obtain a usable acceleration.
The latest accomplishment on this concept is represented by the IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) project by Japan Aerospace Exploration Agency (JAXA), which was launched in May 2010. IKAROS solar sail is currently traveling through the solar system. During its six-month journey to Venus, acceleration and attitude control using the solar sail, rather than thrusters, were successfully tested. Last update from the spacecraft was in May 2014, on a ten-month orbit around the Sun. A scale model of the spacecraft is shown in Figure \(\PageIndex{7}\).
Section Summary
- Electromagnetic waves are created by oscillating charges (which radiate whenever accelerated) and have the same frequency as the oscillation.
- Since the electric and magnetic fields in most electromagnetic waves are perpendicular to the direction in which the wave moves, it is ordinarily a transverse wave.
- Electromagnetic waves carry momentum and exert radiation pressure.
- The momentum of an electromagnetic wave is directly proportional to its energy.
Glossary
- electric field
- a vector quantity ( E ); the lines of electric force per unit charge, moving radially outward from a positive charge and in toward a negative charge
- electric field strength
- the magnitude of the electric field, denoted E -field
- magnetic field
- a vector quantity ( B ); can be used to determine the magnetic force on a moving charged particle
- magnetic field strength
- the magnitude of the magnetic field, denoted B -field
- transverse wave
- a wave, such as an electromagnetic wave, which oscillates perpendicular to the axis along the line of travel
- standing wave
- a wave that oscillates in place, with nodes where no motion happens
- wavelength
- the distance from one peak to the next in a wave
- amplitude
- the height, or magnitude, of an electromagnetic wave
- frequency
- the number of complete wave cycles (up-down-up) passing a given point within one second (cycles/second)
- resonant
- a system that displays enhanced oscillation when subjected to a periodic disturbance of the same frequency as its natural frequency
- oscillate
- to fluctuate back and forth in a steady beat
- radiation pressure
- pressure exerted by an electromagnetic wave on a surface
- solar sail
- a spacecraft that utilizes radiation pressure due to solar radiation in its propulsion
1 Section 16.2: Maxwell’s Equations and Electromagnetic Waves
University Physics II - Thermodynamics, Electricity, and Magnetism


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5.1: Types of Groups
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Groups largely define how we think of ourselves. There are two main types of groups: primary and secondary. As the names suggest, the primary group is the long-term, complex one. People use groups as standards of comparison to define themselves—both who they are and who they are not. Sometimes groups can be used to exclude people or as a tool that strengthens prejudice.
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5.2: The Psychology of Groups
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5.3: Group Dynamics
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5.4: Group Size and Structure
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The size and dynamic of a group greatly affects how members act. Primary groups rarely have formal leaders, although there can be informal leadership. Groups generally are considered large when there are too many members for a simultaneous discussion. In secondary groups there are two types of leadership functions, with expressive leaders focused on emotional health and wellness, and instrumental leaders more focused on results. Further, there are different leadership styles.
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5.5: Group Dynamics and Behavior
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Social scientists have studied how people behave in groups and how groups affect their behavior, attitudes, and perceptions. Their research underscores the importance of groups for social life, but it also points to the dangerous influences groups can sometimes have on their members.
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5.6: Formal Organizations
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Large organizations fall into three main categories: normative/voluntary, coercive, and utilitarian. We live in a time of contradiction: while the pace of change and technology are requiring people to be more nimble and less bureaucratic in their thinking, large bureaucracies like hospitals, schools, and governments are more hampered than ever by their organizational format. At the same time, the past few decades have seen the development of a trend to bureaucratize.
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5.7: Groups, Organizations, and Social Change
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As we consider ways to try to improve our society, the role of groups and organizations becomes very important. This section briefly considers this importance.
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5.8: Social Categorization and Stereotyping
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5.9: Ingroup Favoritism and Prejudice
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5.10: Social Comparison
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When athletes compete in a race, they are able to observe and compare their performance against those of their competitors. In the same way, all people naturally engage in mental comparisons with the people around them during the course of daily life. These evaluations can impact our motivation and feelings. In this module, you will learn about the process of social comparison: its definition, consequences, and the factors that affect it.


4: Intellectual Virtues and Vices
Michael Fitzpatrick contributed quite a bit to this chapter, so Chapter 4 should be seen as a collaboration between Lavin and Fitzpatrick.
Note for Instructors
Starting in edition 4, Chapter 4 on fallacies has been renamed and somewhat rewritten into a chapter on "Intellectual Virtues and Vices," incorporating material from the conclusion and the previous version of the chapter. Thinking about the traditional fallacies under a model of virtue epistemology seemed more in line with the values of this textbook, but they can still be taught as traditional fallacies if that is your preference.
The most significant change is that the "Fallacies of Induction," which was 4.3, have all been moved to the new 8.5, forming part of the chapter on inductive reasoning. This allows those fallacies to be taught in the context in which they are mistakes in reasoning, as teaching fallacies in the context of their positive counterparts seems more pedagogically useful.
Also, the fallacy of equivocation has been moved to 2.2 "Fallacy of Equivocation" , since it is most naturally taught alongside the discussion of the role of language in critical thinking.
All the other fallacies (Relevance and Presumption) remain here, described as intellectual vices.


2.5: Pretrial Procedures
After completing this section, you will be able to
- Understand the multiple procedures involved in the pretrial phase of patent litigation.
- Appreciate the costs involved and the ways they affect the ultimate trial outcome.
The first steps in the pretrial procedure are the filing by the parties of their “initial disclosures” and the holding of the preliminary pretrial conference. xxv Initial disclosures must provide preliminary information about each party’s positions in the case, and disclose the identity and location of witnesses and documents likely to be relevant to the issues in the case. xxvi These disclosures help frame the “discovery,” or information that the parties can request of each other, which is one of the hallmarks of litigation in the United States and one of the drivers of the expense of litigation. The concept is laudable—require each party to disclose the information it has relevant to the case to preclude a “trial by ambush.” But, in practice, discovery can become an endless game of cat and mouse, with costs escalating exponentially. We will talk more about discovery shortly.
The preliminary pretrial conference is usually the first time the parties appear in court before the judge, unless there has been a hearing on a pretrial motion (as discussed above). At this conference, the judge discusses with the parties the issues likely to arise in the case, the time that pretrial discovery is expected to take, and any issues that make the case unique (such as witnesses in foreign countries that require extraordinary means to obtain their testimony for trial). Each party is usually required to submit a report to the court in advance of this conference, proposing what the timeline for the case should be and identifying any unique issues. The court typically issues a scheduling order at, or shortly after, the pretrial conference, specifying dates by which certain activities must be concluded. This order often “splits the baby” between the plaintiff’s and defendant’s proposed schedules (the plaintiff usually seeks speed while the defendant usually seeks delay). The figure below shows a typical scheduling order.
The scheduling order will also usually specify a length of the trial (e.g., 8 trial days), subject to revision at the final pretrial conference. A typical patent trial is scheduled to last from 5 to 20 trial days, but some can take much longer. Let’s look at each step of this schedule to understand what is happening.
Protective Order
Before information is shared between the parties, they usually agree on a protective order, which they will ask the court to enter, that specifies who has access to the confidential information produced during discovery in the litigation. xxvii This is important to all parties, and even third parties that may be asked to produce information during discovery, because sensitive business, technical, and financial information is routinely requested by and produced to each party during the lawsuit. The protective order proscribes that the disclosure of confidential information during discovery is limited to lawyers involved in handling the case, outside experts retained by the lawyers to assist them, and court reporters (who record testimony during the case), videographers (who videotape deposition testimony, as is now common), and court personnel. It is also typical that certain employees of each party (usually in-house lawyers and/or business people directly involved in the oversight of the case) are also permitted to review certain materials, but not financial information of a competitor or future business plans, which are usually excluded from being disclosed to any party employees.
Everyone authorized to see confidential information is under court order to restrict use of the information to the pending lawsuit, not to disclose it to anyone not authorized by the protective order to see it, and requiring that all copies be returned or destroyed at the end of the case.
Discovery
After the preliminary pretrial conference, discovery begins, which results in the exchange of documents, written responses, and witness testimony. xxviii
A request for production allows a party to demand that another party turn over relevant documents and electronically stored information in its possession or control, as well as an inspection of property (such as a manufacturing facility) to take photographs, measurements, and the like. xxix Documents and other tangible items can also be requested from third parties (i.e., people and entities not named as a party in the lawsuit) via subpoena. xxx
Interrogatories are written questions that a party can ask of other parties in the litigation, but not of third parties. Such questions can request any nonprivileged information that is relevant to any party’s claim or defense—including the existence, description, nature, custody, condition, and location of any documents or other tangible things and the identity and location of persons who know of any discoverable information that may be relevant to the subject matter of the litigation. xxxi Interrogatories may also ask for opinions or the legal contentions of another party. The initial limit on the number of interrogatories is 25, including subparts. However, upon a showing of good cause, courts routinely permit additional interrogatories in patent litigation because the issues are usually complex. xxxii Answers to interrogatories are binding on the party providing them and may be used as admissions in the litigation, including at trial.
Depositions are interviews used to elicit testimony from witnesses having relevant knowledge. xxxiii This is similar to eliciting testimony during a trial, but occurs in a conference room with a court reporter present to record what is said. The judge is not present at depositions, but may intervene if a controversy arises. Testimony can also be requested by written questions to a witness, which the witness then answers and returns to the requesting party, called a deposition by written questions. xxxiv
Although in the United States, it is usually required that testimony at trial be presented live, with the opportunity for the opposing party to cross-examine the witness and for the jury and/or judge to assess each witness’s demeanor in person, testimony elicited via depositions during discovery may be used at trial under certain circumstances. xxxv For example, if a witness dies before trial, or is unavailable through no fault of the party seeking to use the deposition testimony, the deposition may be used as testimony at trial in lieu of live testimony from the witness. Also, the deposition testimony of an opposing party or an officer or manager of the opposing party corporation may be used at trial for any purpose. Usually, however, deposition testimony is used primarily to “impeach” a witness testifying live at trial—that is, to show that the witness at trial has changed prior testimony from when they gave the deposition. Videotaped deposition testimony is very effective to show to a judge or jury during trial that the witness has changed the testimony—such as from “No” to “Yes” or the equivalent!
The parties can also demand that another party admit, for purposes of the pending litigation only, the truth of any facts, opinions, or conclusions, or the genuineness of any documents relevant to any party’s claim or defense. Such demands are called requests for admission. xxxvi The responses to these demands are binding on the responding party and can be used to conclusively establish the matters admitted in the litigation, including at trial.
Amendments to the Pleadings
Once initial information is obtained via discovery, the parties may be permitted to amend or supplement their pleadings (i.e., the complaint, answer, counterclaim, etc.) to address information or issues uncovered during the initial discovery. xxxvii For example, the plaintiff may uncover information about other companies, products, or services involved in the infringement and seek to add them to the lawsuit. A defendant may uncover information about invalidity defenses not previously known to it and want to add those to its answer.
Close of Discovery
This is the date by which all requests for documents, information, and depositions must be complete. It is usually interpreted as requiring that all responses to requests for production, interrogatories, and requests for admissions be answered by the end date set by the court, which means that the actual requests must be made sufficiently in advance of this date (typically 31 days—because responses are due to most discovery requests within 30 days) to allow the responses to be due before the cutoff date. Any depositions must also be completed by the date for the close of discovery (although the parties usually agree to finish select depositions after this date in order to accommodate scheduling problems).
Claim Construction Briefing and Hearing
In virtually every patent case, a dispute arises over the meaning of certain language used in the asserted claims of the patents at issue. These are called “claim construction” disputes, and must be resolved by the judge before trial. The parties are permitted to provide their competing arguments in briefs to the court, usually after discovery is completed, and make an oral argument on their respective positions to the court at a claim construction hearing. These hearings are often called Markman hearings , after the name of the case that established that the judge, and not the jury, must decide the proper meaning of disputed claim language. xxxviii
This is a critical juncture in every patent case because the opposing parties try to craft an interpretation of the claim language that supports their respective positions. Most patent claims are drafted using a range of language, from specific to general, in an effort by the patentee (and lawyer) to cover as much territory for the claim as possible. The PTO interprets proposed claims in the broadest reasonable way possible, and then compares their scope with the prior art, before allowing them. The goal of the patentee in dealing with the PTO is to get allowed the broadest claims possible, in order to get the broadest patent coverage possible. But the use of broad, general language in claims permits the parties in later litigation to argue for different interpretations, depending on their interests at the time of litigation. Thus, a plaintiff seeks an interpretation that is broad enough to encompass the defendant’s products and services so that infringement can be proven. In contrast, the defendant proposes a narrow interpretation (or “construction”) that excludes its products and services.
The court resolves the dispute over the meaning of the contested claim terms by referring to the language of the claims, the language and drawings in the patent, and the history of the proceedings in the PTO that led to the issuance of the patent. The written record of that history is preserved in what is call a “file wrapper,” so named because all the written documents making up the history are contained in a three-part file folder, the two outer portions of which fold over and “wrap” the documents within it. The patentee is bound by what it told the PTO to secure allowance of the patent. The court interprets the language according to its ordinary meaning to someone of ordinary skill in the art to which the invention pertains, unless the patentee specially defined the language within the patent or its file wrapper.
Once the claim construction decision is made by the court, the scope of the patent(s) in the case is fixed, and the only remaining issue for trial is whether the claims of the patent(s) as interpreted by the court are broad enough to include the accused products and services of the defendant(s).
Summary Judgment Briefing and Hearing
Summary judgment is a procedure that obviates a trial where one of the parties can show that its opponent cannot win—as a matter of law. xxxix That is, if one party can show that the evidence is so clear that no fact dispute exists (i.e., no reasonable fact finder, whether judge or jury, could decide otherwise) and that the law requires the case be decided in favor of the party moving for summary judgment, the court can decide the case without holding a trial. The judge must decide such motions based only on the applicable law (which the judge determines), the evidence (i.e., documents, interrogatory answers, admissions, and deposition testimony) developed during discovery, and the court’s claim construction decision, giving the benefit of any doubt about the facts to the nonmoving party. If the court finds that a fact relevant to the outcome is in dispute, summary judgment must be denied and a trial held to resolve that factual dispute.
Understandably, these are hotly contested motions. The moving party hopes to avoid the need for a trial, and the uncertainty a jury introduces, by having the judge decide the case in its favor early on. The nonmoving party wants to go to trial, and hope that the fluid events that are the essence of a jury trial will convince the jury to decide the case in its favor.
In recent years, most patent cases are resolved on summary judgment and only a handful go to trial (about 100 per year throughout the country). The primary reason for this phenomenon is the advent of the claim construction (Markman) hearing and the decision by the court, before trial, about how the language of the asserted claims must be interpreted. The court’s claim construction decision resolves most of the uncertainty in a patent case, because what the accused products or services are, and how they operate, is rarely in dispute by the time discovery concludes.
The end result is that the case is often either settled after the claim construction decision, or decided in favor of one side or the other at the summary judgment stage. If summary judgment is granted, the losing party can appeal the decision to the United States Court of Appeals for the Federal Circuit, which is the appellate court to which all decisions in patent cases are appealed.
Final Pretrial Order and Conference
The final pretrial order is the document that sets forth the “ground rules” for the trial. xl It typically identifies all the positions of each party, every issue in dispute in the case that must be resolved by order of the court or at trial, all the documents the parties may seek to introduce into evidence at the trial, and each witness that is expected to be called to testify, either live or via their deposition. The judge issues the order based on a draft prepared by the parties and once issued, it defines the issues that may be raised at the trial. If there is to be a jury trial, the order can rarely be modified after the final pretrial conference. If the trial is before the judge only (referred to as a “bench trial”), the judge may be more lenient in allowing modifications to the final pretrial order because he is the person deciding the case and can adjust more readily than a jury.
Footnotes
- xxv See Rules 12, 16, and 26, Fed. R. Civ. P.
- xxvi See Rule 26(a), Fed. R. Civ. P.
- xxvii See Rule 26(c), Fed. R. Civ. P.
- xxviii See Rules 26-37, Fed. R. Civ. P.
- xxix See Rule 34, Fed. R. Civ. P.
- xxx See Rule 45, Fed. R. Civ. P.
- xxxi See Rules 26(b) and 33(a)(2), Fed. R. Civ. P.
- xxxii See Rule 33(a), Fed, R. Civ. P.
- xxxiii See Rules 27-30, Fed. R. Civ. P.
- xxxiv See Rule 31, Fed. R. Civ. P.
- xxxv See Rule 32, Fed. R. Civ. P.
- xxxvi See Rule 36, Fed. R. Civ. P.
- xxxvii See Rule 15, Fed. R. Civ. P.
- xxxviii Markman , et al. v. Westview Instruments, Inc. , 517 U.S. 370 (1996).
- xxxix See Rule 56, Fed. R. Civ. P.
- xl See Rule 16(e), Fed. R. Civ. P.