Questions to consider:
-
How should you manage passwords and online security?
-
What’s the best way to deal with identity theft?
-
How can you get help and avoid scams?
Identity theft is one of the fastest growing crimes in the United States, and the FBI estimates that more than 10 million new victims are harmed each year.
22
Among the problems contributing to this rapid increase in identity theft are the significant amount of data stored online and the poor security practices of both individuals and companies. In 2017, Equifax announced that their security had been breached and the data of every adult in the country was likely compromised.
23
Passwords and Security
The first line of defense to prevent identity theft is to create strong passwords and take other security measures with your online accounts. An important factor in the strength of a password is the length of the password.
24
This means a password of 12 characters or more is desirable. Consider using pass phrases, or short sentences, rather than passwords. You should vary your pass phrases for each site so a hacker that gets your password can only use it for a single site. Government agencies and security experts are recommending password management software such as LastPass to help with remembering all of these differing passwords.
Another important strategy is to implement two-factor authentication (TFA) on all your online accounts. TFA adds another method of identifying you in addition to your password. Many TFA systems use your cell phone and will text you a code to allow you to log in to your account. A criminal would then need both your password and access to your cell phone to log in. Check the settings on your email, bank website, and other accounts to see how to enable two-factor authentication.
Preventing and Dealing with Identity Theft
Setting strong passwords and enabling two-factor authentication will help keep criminals out of your online banking, email, and other important accounts. Many criminals use lower-tech methods of stealing your identity, however, including tricking or scaring you into giving out information or simply digging through your trash to find account statements.
Never Give Info to Someone Who Contacts You
Never provide a person with personal information unless you initiated the contact. If someone calls you asking for personal information, tell them you’ll call them back. Then ignore the phone number or website they give you, and instead look up the phone number for the organization on their official website. A legitimate company or government agency will never require you to stay on the line with them to solve the problem.
Shred Everything
You should also purchase an inexpensive cross-cut shredder and get in the habit of shredding all paperwork and mail before you throw it away. A good rule of thumb is that if the paper has your name on it, you should shred it before throwing it out.
Order Your Credit Report Annually
At least once per year, you should get your credit report from the credit reporting agencies through annualcreditreport.com, which is the only website approved by the Federal and State governments. The three major agencies -- Transunion, Equifax, and Experian -- all provide the legally mandated free report through this website. Learn how to read a credit report from one of these agencies.
Look for incorrect information or accounts you don’t recognize. If you see accounts you didn’t open on your credit report, file a report with the local police and the local FBI field office. You can also file a complaint with the Federal Trade Commission and Internet Crime Complaint Center.
ANALYSIS QUESTION
Think about your account passwords and your habits related to your identity security. Identify mistakes you have made in the past with your security. What can you start doing today to protect yourself from identity theft or financial fraud?
ACTIVITY
Credit Report Review
Using the sample credit reports below, write an analysis of the person’s credit and how they are managing and using debt. Go through the factors that affect credit, and determine how this person is doing with each factor. What in the report is beneficial, and what is harmful? Carefully review each page for accuracy. Pay particular attention to the personal information, negative credit, and any notes about the person or their credit activity.
Figure 12.13: A sample credit report. (Credit: Based on information from
Experian(opens in new window)
.)
Creating Strong Alliances: Getting Help and Avoiding Scams
As a college student, you are a prime target for predatory practices designed to make the adviser or company rich at your expense.
As you’ve read through this chapter, it may have dawned on you that this personal finance stuff is a lot more complicated than it seems. There are people who have devoted their entire educations and careers to mastering single areas of personal finance, such as taxes, investing, and estate planning. When you feel it’s time to get professional help, there are many qualified professionals who can assist you. Not everyone who calls themselves a financial adviser is actually looking out for your best interest, however.
The terms
financial adviser
,
financial planner
,
wealth manager
, and many other impressive-sounding job titles are not regulated by the government. Anyone can put these job titles on their business cards. You need to be able to differentiate between a qualified professional and those who are untrained product salespeople, predatory financial businesses, or outright scams.
Predatory Practices Aimed at College Students
As a college student, you are a prime target for predatory practices designed to make the adviser or company rich at your expense.
Annuities and Life Insurance
Annuities and life insurance products are often aggressively sold to college students. They are generally inappropriate for college students and even most college graduates because they have high fees and lower returns than many other investment options, and the benefits are rarely needed by young people.
25
Investment Schemes
Regulators identify specialized investments, such as promissory notes, real estate, oil and gas, and gold, as a major threat to investors. Investing systems, including stock picking and buying or selling strategies, are also a concern. Academic research has continually disproven these strategies.
26
If someone is pitching you on their special system or secret strategy, be extremely skeptical. Legitimate investments are regulated by government agencies and are therefore never a secret.
Table 12.6
|
Scam or Scheme
|
Characteristics or Promises
|
Issues and Reasons to Avoid
|
|
“Cash Value” Life Insurance
Often sold as “7702 Plans”
|
Cash value life insurance and similar programs promise that a certain amount of the insurance premiums are set aside as a fund that can be used for expenditures such as college.
|
If they are ever paid out, the consumer must pay taxes and may also pay fees up to 50 percent, losing much of the built-up value.
|
|
Investment Schemes
|
These highly optimistic “sure thing” / “can’t miss” opportunities are specifically geared toward quick rewards or paying for college. They are often specialized investments such as real estate, gold, or oil.
|
Sellers often rely on students’ lack of resources and experience to prevent them from thoroughly investigating the opportunity or properly evaluating the contract terms.
|
|
Advertising, Sales, or Data Entry Opportunities
“I make $40 an hour working from home. . . .”
|
Offers of high pay for what seems like little work are likely too good to be true. “Car wrap” opportunities (driving around with ads on your car), data entry, and online sales opportunities are typical examples.
|
The advertised salaries are often very difficult to achieve and come with significant conditions. Some “pay first” programs utilize fake checks to mislead students.
|
|
Financial Aid Services or Debt Consolidation
|
These services offer to find advantageous financial aid packages for a fee.
27
|
The offers usually do not return as beneficial a package as they promise, and most financial aid can be discovered without paying for it.
|
|
Phone Scams
“The IRS has detected tax fraud. . . .”
“This will be an attempt to avoid an initial appearance before a grand jury for a criminal offense. . . .”
|
Phone scammers use threatening, official-sounding messages to scare recipients. They often demand immediate return calls or request account or identifying information. These scams are not unique to college students.
|
As official as they sound, these are scams. The perpetrators will use any account information you provide to invade your privacy or steal your money.
|
|
Too-Good-to-Be-True Credit Cards
|
Credit cards with very low introductory interest rates, a promise of points, or other impressive-sounding benefits may be offered to students on college campuses, especially during events.
|
Low rates can explode into high rates or incur fees after a brief period or a single late payment. This is not technically fraudulent, but be very careful when reading the terms.
|
|
Freebie or Social Media Survey Scams
|
Many legitimate companies will offer free products or ask students to complete surveys, but high-risk offerings will ask for personal information or account information.
|
Free products or compensation may not arrive, and even if they do, they may not offset the risk of giving up account information.
|
|
Fake Universities or Degree Programs (Diploma Mills)
|
Offers may sound very legitimate and similar to real colleges. They often promise significant financial aid or degrees in just weeks or months.
28
|
A certificate from a school with no accreditation or a poor reputation is a waste of time and money. Be certain that any college or certificate program is formally accredited; review the credentials of current faculty, and determine the job placement of alumni.
|
Sources of Good Information and Help
With all the high-cost, predatory, and scam financial advice out there, it is important to know where to turn for help.
Personal Finance Classes
One option is to look for a personal finance class, which will take the concepts found in this chapter and expand on them for an entire semester. Your college may have a financial literacy, personal finance, or money management class available.
Be wary of personal finance or investing classes offered through other sources, however, as many include hidden sales agendas and aggressive pitches to buy a company’s financial products. Never make an investment decision, buy a product, or sign a contract at a class, and always seek advice from others on any opportunity.
Websites and Government Resources
There are a ridiculous number of websites available to the public to help with your personal finances. When choosing a website for help, lean toward sites run by a legitimate government agencies or nonprofit organizations.
The first place you should look for help with finances is the official website of related government agencies. If you have a question about insurance, look to your state’s insurance commissioner website. If you are having problems with your apartment, contact your city’s housing authority.
Government agencies not only have the authoritative word on any legal matter, but are also generally unbiased. The downside to government websites is that they can be hard to understand, with legal wording taken directly from the law. Some government agencies are also prohibited from giving advice to the public, leaving it up to you to apply the information they provide.
There are also many nonprofit organizations that have been established to assist the public with finances. Nonprofit organizations may have information that is easier to understand, and they may also be able to offer personal advice.
Official Government Websites
-
Personal Finance: Consumer Financial Protection Bureau, consumerfinance.gov
-
Taxes: Internal Revenue Service, irs.gov
-
Retirement: Social Security Administration, ssa.gov
-
Investing: Securities Exchange Commission, sec.gov
-
Investing: North American Securities Administrators Association, nasaa.org (state and provincial investment regulators)
Nonprofit Organization Websites
-
National Endowment for Financial Education, nefe.org
-
National Foundation for Credit Counseling, nfcc.org
-
Consumer Reports, consumerreports.org (national consumer advocacy organization)
-
Purposeful Finance, purposefulfinance.org (a nonprofit organization run by this chapter’s author)
Your College’s Financial Aid Office
The financial aid or student aid office of your college may also be a good place to look for financial help, especially surrounding student loans. It is important to realize, however, that a conflict of interest exists between you and the financial aid adviser. Your college’s financial aid office is charged with helping you find the money to go to college, but it isn’t charged with making sure you don’t take on too much student debt. It is possible to get good advice on getting money to pay for college that is also bad advice for your future finances.
College financial aid counselors are also generally not trained in other areas of finance and should not be relied on for advice on investing, taxes, noncollege debt, or other financial matters. To get help with these areas, consult a qualified professional who can guide you with fewer conflicts of interest, such as the professionals listed below.
ANALYSIS QUESTION
Talk with your parents or other family members about their experience with finances, including financial advisers, taxes, legal issues, and investing. When could they have used professional advice in their past? Did they have bad experiences with getting advice that wasn’t best for them? How has a lack of
good
advisers harmed your family financially (even if just because they could have had more money)?
Footnotes
-
archives.fbi.gov/archives/ne...ventidt_102104
-
purposefulfinance.org
[www.purposefulfinance.org]
-
Information Security Institute. “Password Security:Complexity Versus Length.” 2019.
resources.infosecinstitute.com
[resources.infosecinstitute.c...ity-vs-length]
-
North American Securities Administrators Association. Top Investor Threats.
nasaa.org
[nasaa.org]
/
-
Kadan, Maduriera, Wang and Zach. “Stock Picking, Industry Picking, and Market Timing in Sell-Side Research.” Singapore Management University. 2012.
-
Boswell, Brian. “Don’t Get Suckered By These College Savings Plans.” Forbes.com. 2019.
-
Creel, Wes. “How Cn I Tell if a Degree is Legitiamte or a Scam.” Abound/Finish College.


16.3: Eukaryotic Epigenetic Gene Regulation
Skills to Develop
- Explain the process of epigenetic regulation
- Describe how access to DNA is controlled by histone modification
Eukaryotic gene expression is more complex than prokaryotic gene expression because the processes of transcription and translation are physically separated. Unlike prokaryotic cells, eukaryotic cells can regulate gene expression at many different levels. Eukaryotic gene expression begins with control of access to the DNA. This form of regulation, called epigenetic regulation, occurs even before transcription is initiated.
Epigenetic Control: Regulating Access to Genes within the Chromosome
The human genome encodes over 20,000 genes; each of the 23 pairs of human chromosomes encodes thousands of genes. The DNA in the nucleus is precisely wound, folded, and compacted into chromosomes so that it will fit into the nucleus. It is also organized so that specific segments can be accessed as needed by a specific cell type.
The first level of organization, or packing, is the winding of DNA strands around histone proteins. Histones package and order DNA into structural units called nucleosome complexes, which can control the access of proteins to the DNA regions (Figure \(\PageIndex{1}\)a). Under the electron microscope, this winding of DNA around histone proteins to form nucleosomes looks like small beads on a string (Figure \(\PageIndex{1}\)b). These beads (histone proteins) can move along the string (DNA) and change the structure of the molecule.
If DNA encoding a specific gene is to be transcribed into RNA, the nucleosomes surrounding that region of DNA can slide down the DNA to open that specific chromosomal region and allow for the transcriptional machinery (RNA polymerase) to initiate transcription (Figure \(\PageIndex{2}\)). Nucleosomes can move to open the chromosome structure to expose a segment of DNA, but do so in a very controlled manner.
Art Connection
In females, one of the two X chromosomes is inactivated during embryonic development because of epigenetic changes to the chromatin. What impact do you think these changes would have on nucleosome packing?
How the histone proteins move is dependent on signals found on both the histone proteins and on the DNA. These signals are tags added to histone proteins and DNA that tell the histones if a chromosomal region should be open or closed (Figure \(\PageIndex{3}\)) depicts modifications to histone proteins and DNA). These tags are not permanent, but may be added or removed as needed. They are chemical modifications (phosphate, methyl, or acetyl groups) that are attached to specific amino acids in the protein or to the nucleotides of the DNA. The tags do not alter the DNA base sequence, but they do alter how tightly wound the DNA is around the histone proteins. DNA is a negatively charged molecule; therefore, changes in the charge of the histone will change how tightly wound the DNA molecule will be. When unmodified, the histone proteins have a large positive charge; by adding chemical modifications like acetyl groups, the charge becomes less positive.
The DNA molecule itself can also be modified. This occurs within very specific regions called CpG islands. These are stretches with a high frequency of cytosine and guanine dinucleotide DNA pairs (CG) found in the promoter regions of genes. When this configuration exists, the cytosine member of the pair can be methylated (a methyl group is added). This modification changes how the DNA interacts with proteins, including the histone proteins that control access to the region. Highly methylated (hypermethylated) DNA regions with deacetylated histones are tightly coiled and transcriptionally inactive.
This type of gene regulation is called epigenetic regulation. Epigenetic means “around genetics.” The changes that occur to the histone proteins and DNA do not alter the nucleotide sequence and are not permanent. Instead, these changes are temporary (although they often persist through multiple rounds of cell division) and alter the chromosomal structure (open or closed) as needed. A gene can be turned on or off depending upon the location and modifications to the histone proteins and DNA. If a gene is to be transcribed, the histone proteins and DNA are modified surrounding the chromosomal region encoding that gene. This opens the chromosomal region to allow access for RNA polymerase and other proteins, called transcription factors , to bind to the promoter region, located just upstream of the gene, and initiate transcription. If a gene is to remain turned off, or silenced, the histone proteins and DNA have different modifications that signal a closed chromosomal configuration. In this closed configuration, the RNA polymerase and transcription factors do not have access to the DNA and transcription cannot occur (Figure \(\PageIndex{3}\)).
Link to Learning
View this video that describes how epigenetic regulation controls gene expression.
Summary
In eukaryotic cells, the first stage of gene expression control occurs at the epigenetic level. Epigenetic mechanisms control access to the chromosomal region to allow genes to be turned on or off. These mechanisms control how DNA is packed into the nucleus by regulating how tightly the DNA is wound around histone proteins. The addition or removal of chemical modifications (or flags) to histone proteins or DNA signals to the cell to open or close a chromosomal region. Therefore, eukaryotic cells can control whether a gene is expressed by controlling accessibility to transcription factors and the binding of RNA polymerase to initiate transcription.
Art Connections
Figure \(\PageIndex{2}\): In females, one of the two X chromosomes is inactivated during embryonic development because of epigenetic changes to the chromatin. What impact do you think these changes would have on nucleosome packing?
- Answer
-
The nucleosomes would pack more tightly together.
Glossary
- transcription factor
- protein that binds to the DNA at the promoter or enhancer region and that influences transcription of a gene


2.4: Partial Derivatives
So far, we have focused on functions which take a single input. Functions can also take multiple inputs; for instance, a function \(f(x,y)\) maps two input numbers, \(x\) and \(y\) , and outputs a number. In general, the inputs are allowed to vary independently of one another. The partial derivative of such a function is its derivative with respect to one of its inputs, keeping the others fixed. For example,
\[f(x,y) = \sin(2x - 3 y^2)\]
has partial derivatives
\[\begin{align} \frac{\partial f}{\partial x} &= 2\cos(2x-3y^2), \\[4pt] \frac{\partial f}{\partial y} &= - 6\cos(2x-3y^2).\end{align}\]
Change of variables
We saw in Section 2.1 that single-variable functions obey a derivative composition rule,
\[\frac{d}{dx}\, f\big(g(x)\big) = g'(x) \, f'\big(g(x)\big).\] This composition rule has a important generalization for partial derivatives, which is related to the physical concept of a change of coordinates . Suppose a function \(f(x,y)\) takes two inputs \(x\) and \(y\) , and we wish to express them using a different coordinate system denoted by \(u\) and \(v\) . In general, each coordinate in the old system depends on both coordinates in the new system:
\[x = x(u,v), \quad y = y(u,v).\]
Expressed in the new coordinates, the function is
\[F(u,v) \equiv f\big(x(u,v), y(u,v)\big).\] It can be shown that the transformed function’s partial derivatives obey the composition rule
\[\begin{align} \frac{\partial F}{\partial u} &= \frac{\partial f}{\partial x} \frac{\partial x}{\partial u} + \frac{\partial f}{\partial y} \frac{\partial y}{\partial u}\\[4pt] \frac{\partial F}{\partial v} &= \frac{\partial f}{\partial x} \frac{\partial x}{\partial v} + \frac{\partial f}{\partial y} \frac{\partial y}{\partial v}.\end{align}\]
On the right-hand side of these equations, the partial derivatives are to be expressed in terms of the new coordinates \((u,v)\) . For example,
\[\frac{\partial f}{\partial x} = \left.\frac{\partial f}{\partial x}\right|_{x = x(u,v), \;y= y(u,v)}\]
The generalization of this rule to more than two inputs is straightforward. For a function \(f(x_1, \dots, x_N)\) , a change of coordinates \(x_i = x_i(u_1, \dots, u_N)\) involves the composition
\[F(u_1, \dots, u_N) = f\big(x_1(u_1,\dots,u_N\big), \dots), \quad \frac{\partial F}{\partial u_i} = \sum_{j=1}^N \frac{\partial x_j}{\partial u_i} \frac{\partial f}{\partial x_j}.\]
Example \(\PageIndex{1}\)
In two dimensions, Cartesian and polar coordinates are related by
\[x = r\cos\theta, \quad y = r\sin\theta.\] Given a function \(f(x,y)\) , we can re-write it in polar coordinates as \(F(r,\theta)\) . The partial derivatives are related by
\[\begin{align} \frac{\partial F}{\partial r} &= \frac{\partial f}{\partial x} \frac{\partial x}{\partial r} + \frac{\partial f}{\partial y} \frac{\partial y}{\partial r} = \frac{\partial f}{\partial x} \cos\theta + \frac{\partial f}{\partial y} \sin\theta. \\[4pt] \frac{\partial F}{\partial \theta} &= \frac{\partial f}{\partial x} \frac{\partial x}{\partial \theta} + \frac{\partial f}{\partial y} \frac{\partial y}{\partial \theta} = -\frac{\partial f}{\partial x} r\,\sin\theta + \frac{\partial f}{\partial y} r\cos\theta. \end{align}\]
Partial differential equations
A partial differential equation is a differential equation involving multiple partial derivatives (as opposed to an ordinary differential equation, which involves derivatives with respect to a single variable). An example of a partial differential equation encountered in physics is Laplace’s equation,
\[\frac{\partial^2 \Phi}{\partial x^2} + \frac{\partial^2 \Phi}{\partial y^2} + \frac{\partial^2 \Phi}{\partial z^2}= 0,\] which describes the electrostatic potential \(\Phi(x,y,z)\) at position \((x,y,z)\) , in the absence of any electric charges.
Partial differential equations are considerably harder to solve than ordinary differential equations. In particular, their boundary conditions are more complicated to specify: whereas each boundary condition for an ordinary differential equation consists of a single number (e.g., the value of \(f(x)\) at some point \(x = x_0\) ), each boundary condition for a partial differential equation consists of a function (e.g., the values of \(\Phi(x,y,z)\) along some curve \(g(x,y,z) = 0\) ).


9.1: Why It Matters- Academic Argument
Why learn to evaluate and construct academic arguments?
You may question why you need to study argument. After all, the internet often seems as though it is one big shouting match—arguing is everywhere! But academic argument is different from much of the arguing that happens in day-to-day life. Academic arguments value certain approaches and follow established strategies.
In this module, you will be introduced to methods for composing an effective academic argument, including constructing an arguable thesis, building common ground, avoiding logical fallacies, and refuting counterargument. These strategies will not only benefit you in your academic career but will also help you be more persuasive in your professional and personal life.
Contributors and Attributions
- Why It Matters: Academic Argument. Provided by : University of Mississippi. License : CC BY: Attribution
- Argument?. Authored by : Ayana T. Miller. Located at : www.flickr.com/photos/lomama72/10219973084/. License : CC BY-ND: Attribution-NoDerivatives


28.3: Embryonic Development
By the end of this section, you will be able to:
- Distinguish the stages of embryonic development that occur before implantation
- Describe the process of implantation
- List and describe four embryonic membranes
- Explain gastrulation
- Describe how the placenta is formed and identify its functions
- Explain how an embryo transforms from a flat disc of cells into a three-dimensional shape resembling a human
- Summarize the process of organogenesis
Throughout this chapter, we will express embryonic and fetal ages in terms of weeks from fertilization, commonly called conception. The period of time required for full development of a fetus in utero is referred to as gestation (gestare = “to carry” or “to bear”). It can be subdivided into distinct gestational periods. The first 2 weeks of prenatal development are referred to as the pre-embryonic stage. A developing human is referred to as an embryo during weeks 3–8, and a fetus from the ninth week of gestation until birth. In this section, we’ll cover the pre-embryonic and embryonic stages of development, which are characterized by cell division, migration, and differentiation. By the end of the embryonic period, all of the organ systems are structured in rudimentary form, although the organs themselves are either nonfunctional or only semi-functional.
Pre-implantation Embryonic Development
Following fertilization, the zygote and its associated membranes, together referred to as the conceptus , continue to be projected toward the uterus by peristalsis and beating cilia of the epithelial cells of the Fallopian tube. During its journey to the uterus, the zygote undergoes five or six rapid mitotic cell divisions. Although each cleavage results in more cells, it does not increase the total volume of the conceptus (Figure \(\PageIndex{1}\)). Each daughter cell produced by cleavage is called a blastomere (blastos = “germ,” in the sense of a seed or sprout).
Approximately 3 days after fertilization, a 16-cell conceptus reaches the uterus. The cells that had been loosely grouped are now compacted and look more like a solid mass. The name given to this structure is the morula (morula = “little mulberry”). Once inside the uterus, the conceptus floats freely for several more days. It continues to divide, creating a ball of approximately 100 cells, and consuming nutritive endometrial secretions called uterine milk while the uterine lining thickens. The ball of now tightly bound cells starts to secrete fluid and organize themselves around a fluid-filled cavity, the blastocoel . At this developmental stage, the conceptus is referred to as a blastocyst . Within this structure, a group of cells forms into an inner cell mass , which is fated to become the embryo. The cells that form the outer shell are called trophoblasts (trophe = “to feed” or “to nourish”). These cells will develop into the chorionic sac and the fetal portion of the placenta (the organ of nutrient, waste, and gas exchange between a pregnant person and the developing offspring).
The inner mass of embryonic cells is totipotent during this stage, meaning that each cell has the potential to differentiate into any cell type in the human body. Totipotency lasts for only a few days before the cells’ fates are set as being the precursors to a specific lineage of cells.
As the blastocyst forms, the trophoblast excretes enzymes that begin to degrade the zona pellucida. In a process called “hatching,” the conceptus breaks free of the zona pellucida in preparation for implantation.
Interactive Link
View this time-lapse movie of a conceptus starting at day 3. What is the first structure you see? At what point in the movie does the blastocoel first appear? What event occurs at the end of the movie?
Implantation
At the end of the first week, the blastocyst comes in contact with the uterine wall and adheres to it, embedding itself in the uterine lining via the trophoblast cells. Thus begins the process of implantation , which signals the end of the pre-embryonic stage of development (Figure \(\PageIndex{2}\)). Implantation can be accompanied by minor bleeding. The blastocyst typically implants in the fundus of the uterus or on the posterior wall. However, if the endometrium is not fully developed and ready to receive the blastocyst, the blastocyst will detach and find a better spot. A significant percentage (50–75 percent) of blastocysts fail to implant; when this occurs, the blastocyst is shed with the endometrium during menses. The high rate of implantation failure is one reason why pregnancy typically requires several ovulation cycles to achieve.
When implantation succeeds and the blastocyst adheres to the endometrium, the superficial cells of the trophoblast fuse with each other, forming the syncytiotrophoblast , a multinucleated body that digests endometrial cells to firmly secure the blastocyst to the uterine wall. In response, the uterine mucosa rebuilds itself and envelops the blastocyst (Figure \(\PageIndex{3}\)). The trophoblast secretes human chorionic gonadotropin (hCG) , a hormone that directs the corpus luteum to survive, enlarge, and continue producing progesterone and estrogen to suppress menses. These functions of hCG are necessary for creating an environment suitable for the developing embryo. As a result of this increased production, hCG accumulates in the maternal bloodstream and is excreted in the urine. Implantation is complete by the middle of the second week. Just a few days after implantation, the trophoblast has secreted enough hCG for an at-home urine pregnancy test to give a positive result.
Most of the time an embryo implants within the body of the uterus in a location that can support growth and development. However, in one to two percent of cases, the embryo implants either outside the uterus (an ectopic pregnancy ) or in a region of uterus that can create complications for the pregnancy. If the embryo implants in the inferior portion of the uterus, the placenta can potentially grow over the opening of the cervix, a condition call placenta previa .
Disorders of the...
Development of the Embryo
In the vast majority of ectopic pregnancies, the embryo does not complete its journey to the uterus and implants in the uterine tube, referred to as a tubal pregnancy. However, there are also ovarian ectopic pregnancies (in which the egg never left the ovary) and abdominal ectopic pregnancies (in which an egg was “lost” to the abdominal cavity during the transfer from ovary to uterine tube, or in which an embryo from a tubal pregnancy re-implanted in the abdomen). Once in the abdominal cavity, an embryo can implant into any well-vascularized structure—the rectouterine cavity (Douglas’ pouch), the mesentery of the intestines, and the greater omentum are some common sites.
Tubal pregnancies can be caused by scar tissue within the tube following a sexually transmitted bacterial infection. The scar tissue impedes the progress of the embryo into the uterus—in some cases “snagging” the embryo and, in other cases, blocking the tube completely. Approximately one half of tubal pregnancies resolve spontaneously. Implantation in a uterine tube causes bleeding, which appears to stimulate smooth muscle contractions and expulsion of the embryo. In the remaining cases, medical or surgical intervention is necessary. If an ectopic pregnancy is detected early, the embryo’s development can be arrested by the administration of the cytotoxic drug methotrexate, which inhibits the metabolism of folic acid. If diagnosis is late and the uterine tube is already ruptured, surgical repair is essential.
Even if the embryo has successfully found its way to the uterus, it does not always implant in an optimal location (the fundus or the posterior wall of the uterus). Placenta previa can result if an embryo implants close to the internal os of the uterus (the internal opening of the cervix). As the fetus grows, the placenta can partially or completely cover the opening of the cervix (Figure \(\PageIndex{4}\)). Although it occurs in only 0.5 percent of pregnancies, placenta previa is the leading cause of antepartum hemorrhage (profuse vaginal bleeding after week 24 of pregnancy but prior to childbirth).
Embryonic Membranes
During the second week of development, with the embryo implanted in the uterus, cells within the blastocyst start to organize into layers. Some grow to form the extra-embryonic membranes needed to support and protect the growing embryo: the amnion, the yolk sac, the allantois, and the chorion.
At the beginning of the second week, the cells of the inner cell mass form into a two-layered disc of embryonic cells, and a space—the amniotic cavity —opens up between it and the trophoblast (Figure \(\PageIndex{5}\)). Cells from the upper layer of the disc (the epiblast ) extend around the amniotic cavity, creating a membranous sac that forms into the amnion by the end of the second week. The amnion fills with amniotic fluid and eventually grows to surround the embryo. Early in development, amniotic fluid consists almost entirely of a filtrate of maternal plasma, but as the kidneys of the fetus begin to function at approximately the eighth week, they add urine to the volume of amniotic fluid. Floating within the amniotic fluid, the embryo—and later, the fetus—is protected from trauma and rapid temperature changes. It can move freely within the fluid and can prepare for swallowing and breathing out of the uterus.
On the ventral side of the embryonic disc, opposite the amnion, cells in the lower layer of the embryonic disk (the hypoblast ) extend into the blastocyst cavity and form a yolk sac . The yolk sac supplies some nutrients absorbed from the trophoblast and also provides primitive blood circulation to the developing embryo for the second and third week of development. When the placenta takes over nourishing the embryo at approximately week 4, the yolk sac has been greatly reduced in size and its main function is to serve as the source of blood cells and germ cells (cells that will give rise to gametes). During week 3, a finger-like outpocketing of the yolk sac develops into the allantois , a primitive excretory duct of the embryo that will become part of the urinary bladder. Together, the stalks of the yolk sac and allantois establish the outer structure of the umbilical cord.
The last of the extra-embryonic membranes is the chorion , which is the one membrane that surrounds all others. The development of the chorion will be discussed in more detail shortly, as it relates to the growth and development of the placenta.
Embryogenesis
As the third week of development begins, the two-layered disc of cells becomes a three-layered disc through the process of gastrulation , during which the cells transition from totipotency to multipotency. The embryo, which takes the shape of an oval-shaped disc, forms an indentation called the primitive streak along the dorsal surface of the epiblast. A node at the caudal or “tail” end of the primitive streak emits growth factors that direct cells to multiply and migrate. Cells migrate toward and through the primitive streak and then move laterally to create two new layers of cells. The first layer is the endoderm , a sheet of cells that displaces the hypoblast and lies adjacent to the yolk sac. The second layer of cells fills in as the middle layer, or mesoderm . The cells of the epiblast that remain (not having migrated through the primitive streak) become the ectoderm (Figure \(\PageIndex{6}\)).
Each of these germ layers will develop into specific structures in the embryo. Whereas the ectoderm and endoderm form tightly connected epithelial sheets, the mesodermal cells are less organized and exist as a loosely connected cell community. The ectoderm gives rise to cell lineages that differentiate to become the central and peripheral nervous systems, sensory organs, epidermis, hair, and nails. Mesodermal cells ultimately become the skeleton, muscles, connective tissue, heart, blood vessels, and kidneys. The endoderm goes on to form the epithelial lining of the gastrointestinal tract, liver, and pancreas, as well as the lungs (Figure \(\PageIndex{7}\)).
Development of the Placenta
During the first several weeks of development, the cells of the endometrium—referred to as decidual cells—nourish the nascent embryo. During prenatal weeks 4–12, the developing placenta gradually takes over the role of feeding the embryo, and the decidual cells are no longer needed. The mature placenta is composed of tissues derived from the embryo, as well as maternal tissues of the endometrium. The placenta connects to the conceptus via the umbilical cord , which carries deoxygenated blood and wastes from the fetus through two umbilical arteries; nutrients and oxygen are carried from the pregnant person to the fetus through the single umbilical vein. The umbilical cord is surrounded by the amnion, and the spaces within the cord around the blood vessels are filled with Wharton’s jelly, a mucous connective tissue.
The maternal portion of the placenta develops from the deepest layer of the endometrium, the decidua basalis. To form the embryonic portion of the placenta, the syncytiotrophoblast and the underlying cells of the trophoblast (cytotrophoblast cells) begin to proliferate along with a layer of extraembryonic mesoderm cells. These form the chorionic membrane , which envelops the entire conceptus as the chorion. The chorionic membrane forms finger-like structures called chorionic villi that burrow into the endometrium like tree roots, making up the fetal portion of the placenta. The cytotrophoblast cells perforate the chorionic villi, burrow farther into the endometrium, and remodel maternal blood vessels to augment maternal blood flow surrounding the villi. Meanwhile, fetal mesenchymal cells derived from the mesoderm fill the villi and differentiate into blood vessels, including the three umbilical blood vessels that connect the embryo to the developing placenta (Figure \(\PageIndex{8}\)).
The placenta develops throughout the embryonic period and during the first several weeks of the fetal period; placentation is complete by weeks 14–16. As a fully developed organ, the placenta provides nutrition and excretion, respiration, and endocrine function (Table \(\PageIndex{1}\) and Figure \(\PageIndex{10}\)). It receives blood from the fetus through the umbilical arteries. Capillaries in the chorionic villi filter fetal wastes out of the blood and return clean, oxygenated blood to the fetus through the umbilical vein. Nutrients and oxygen are transferred from maternal blood surrounding the villi through the capillaries and into the fetal bloodstream. Some substances move across the placenta by simple diffusion. Oxygen, carbon dioxide, and any other lipid-soluble substances take this route. Other substances move across by facilitated diffusion. This includes water-soluble glucose. The fetus has a high demand for amino acids and iron, and those substances are moved across the placenta by active transport.
Maternal and fetal blood does not commingle because blood cells cannot move across the placenta. This separation prevents the pregnant person's cytotoxic T cells from reaching and subsequently destroying the fetus, which bears “non-self” antigens. Further, it ensures the fetal red blood cells do not enter the pregnant person's circulation and trigger antibody development (if they carry “non-self” antigens)—at least until the final stages of pregnancy or birth. This is the reason that, even in the absence of preventive treatment, an Rh − person doesn’t develop antibodies that could cause hemolytic disease in their first Rh + fetus.
Although blood cells are not exchanged, the chorionic villi provide ample surface area for the two-way exchange of substances between maternal and fetal blood. The rate of exchange increases throughout gestation as the villi become thinner and increasingly branched. The placenta is permeable to lipid-soluble fetotoxic substances: alcohol, nicotine, barbiturates, antibiotics, certain pathogens, and many other substances that can be dangerous or fatal to the developing embryo or fetus. For these reasons, pregnant people should avoid fetotoxic substances. Alcohol consumption by pregnant people, for example, can result in a range of abnormalities referred to as fetal alcohol spectrum disorders (FASD). These include organ and facial malformations, as well as cognitive and behavioral disorders.
| Nutrition and digestion | Respiration | Endocrine function |
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Organogenesis
Following gastrulation, rudiments of the central nervous system develop from the ectoderm in the process of neurulation (Figure \(\PageIndex{11}\)). Specialized neuroectodermal tissues along the length of the embryo thicken into the neural plate . During the fourth week, tissues on either side of the plate fold upward into a neural fold . The two folds converge to form the neural tube . The tube lies atop a rod-shaped, mesoderm-derived notochord , which eventually becomes the nucleus pulposus of intervertebral discs. Block-like structures called somites form on either side of the tube, eventually differentiating into the axial skeleton, skeletal muscle, and dermis. During the fourth and fifth weeks, the anterior neural tube dilates and subdivides to form vesicles that will become the brain structures.
Folate, one of the B vitamins, is important to the healthy development of the neural tube. A deficiency of maternal folate in the first weeks of pregnancy can result in neural tube defects, including spina bifida—a birth defect in which spinal tissue protrudes through the newborn’s vertebral column, which has failed to completely close. A more severe neural tube defect is anencephaly, a partial or complete absence of brain tissue.
The embryo, which begins as a flat sheet of cells, begins to acquire a cylindrical shape through the process of embryonic folding (Figure \(\PageIndex{12}\)). The embryo folds laterally and again at either end, forming a C-shape with distinct head and tail ends. The embryo envelops a portion of the yolk sac, which protrudes with the umbilical cord from what will become the abdomen. The folding essentially creates a tube, called the primitive gut, that is lined by the endoderm. The amniotic sac, which was sitting on top of the flat embryo, envelops the embryo as it folds.
Within the first 8 weeks of gestation, a developing embryo establishes the rudimentary structures of all of its organs and tissues from the ectoderm, mesoderm, and endoderm. This process is called organogenesis .
Like the central nervous system, the heart also begins its development in the embryo as a tube-like structure, connected via capillaries to the chorionic villi. Cells of the primitive tube-shaped heart are capable of electrical conduction and contraction. The heart begins beating in the beginning of the fourth week, although it does not actually pump embryonic blood until a week later, when the oversized liver has begun producing red blood cells. (This is a temporary responsibility of the embryonic liver that the bone marrow will assume during fetal development.) During weeks 4–5, the eye pits form, limb buds become apparent, and the rudiments of the pulmonary system are formed.
During the sixth week, uncontrolled fetal limb movements begin to occur. The gastrointestinal system develops too rapidly for the embryonic abdomen to accommodate it, and the intestines temporarily loop into the umbilical cord. Paddle-shaped hands and feet develop fingers and toes by the process of apoptosis (programmed cell death), which causes the tissues between the fingers to disintegrate. By week 7, the facial structure is more complex and includes nostrils, outer ears, and lenses (Figure \(\PageIndex{13}\)). By the eighth week, the head is nearly as large as the rest of the embryo’s body, and all major brain structures are in place. The external genitalia are apparent, but at this point, male and female embryos are indistinguishable. Bone begins to replace cartilage in the embryonic skeleton through the process of ossification. By the end of the embryonic period, the embryo is approximately 3 cm (1.2 in) from crown to rump and weighs approximately 8 g (0.25 oz).
Interactive Link
Watch this video to view the process of embryogenesis from fertilization through pregnancy to birth. Can you identify when neurulation occurs in the embryo?


2.6: Library discovery tools
The ISU Library subscribes to thousands of electronic journals, scholarly indexes, e-books, and many other types of online resources. Traditionally, libraries depended on a finding tool called the library catalog, which told you what materials the library owned and where those materials were located in the library building. Much the same way that our library has a larger collection compared to other libraries you may have used in the past, library discovery tools help researchers find a wider range of resources beyond the items a library owns. Our library discovery tool is called Quick Search .
Quick Search basics
Quick Search is a powerful search tool that has two interfaces you’ll encounter. The first and most prominent interface is a simple search box which is accessed through the library’s homepage . Quick Search’s simple search is commonly used in the beginning of your research. There is also an advanced search interface, which gives you more control over your search from the start by introducing filters you can apply. We’ll discuss advanced search more in chapter 3.
Quick Search is particularly useful when you’re starting your search from a general topic or don’t have a specific source in mind. Try typing a few keywords or an author’s name into the simple search box and exploring what you find.
Quick Search not only incorporates the traditional functions of a library catalog by helping you find what we own, but also searches:
- Articles from some of the library’s online indexes and databases,
- E-books and book chapters,
- Digital films, art, and music,
- Digital content from the Special Collections and University Archives,
- Online course and research guides,
- Open access web resources such as books from Project Gutenberg or the Directory of Open Access Books,
- Other items that the library doesn’t have direct access to, but which you can request through Interlibrary Loan, and more.
Because Quick Search searches both the library’s physical collections and some indexes and databases, it can be a straightforward starting place for finding both books and articles. This is particularly true for interdisciplinary topics. Be aware that Quick Search does not find every article the ISU Library provides access to, just ones from indexes that are compatible with it.
Quick Search features
Quick Search has a lot of flexible and useful features. For example, Quick Search uses labels in your results list so you can instantly tell which items are books, which are DVDs or CDs, and so on. Another helpful feature generates citations for sources you’ve found. You can also email item descriptions from your search results to yourself or someone else. Additionally, you can log in with your NetID to access more features.
Strengths and weaknesses of Quick Search
Strengths
- It covers a wide range of topics and materials.
- It has an easy-to-use simple search interface.
- It can find books and other materials the library provides access to in addition to articles.
Weaknesses
- Because it covers a wide range of subjects and material types, you may get an unreasonable number of results.
- It has less extensive subject coverage when compared to subject-specific indexes.
- Unlike subject-specific indexes, it lacks highly specialized search tools for every subject area (e.g. searching by chemical formula, study methodology).


1.12.3: Cancer Screening and Symptoms
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Before learning about the various cancer symptoms, it is important to note that many cancers have no symptoms, rather they are asymptomatic. It is important to get annual checkups and screenings to detect cancer. For example, women should get pap tests annually and mammograms after 40 (or earlier if breast cancer runs in their family. Men and women should get a colonoscopy every 10 years starting at 45.
Early detection is key for cancer survival!
The acronym CAUTION is a helpful reminder of the most common symptoms of cancer that you should watch out for. If you see any of the following symptoms please make an appointment with your primary care physician.
Symptoms as related to type of cancer include:
Lung and bronchus
- Coughing that gets worse or doesn’t go away.
- Chest pain.
- Shortness of breath.
- Wheezing.
- Coughing up blood.
- Feeling very tired all the time.
- Weight loss with no known cause.
Breast (female)
- New lump in the breast or underarm (armpit).
- Thickening or swelling of part of the breast.
- Irritation or dimpling of breast skin.
- Redness or flaky skin in the nipple area or the breast.
- Pulling in of the nipple or pain in the nipple area.

- Any change in the size or the shape of the breast.
- Pain in any area of the breast.
Prostate
- Difficulty starting urination.
- Weak or interrupted flow of urine.
- Frequent urination, especially at night.
- Difficulty emptying the bladder completely.
- Pain or burning during urination.
- Blood in the urine or semen.
- Pain in the back, hips, or pelvis that doesn’t go away.
- Painful ejaculation.
Colorectal
- A change in bowel habits.
- Blood in or on your stool (bowel movement).
- Diarrhea, constipation, or feeling that the bowel does not empty all the way.
- Abdominal pain, aches, or cramps that don’t go away.
- Weight loss and you don’t know why.
Pancreas
- often asymptomatic
- jaundice
- Abdominal or back pain.
- nausea and vomiting.
- weight loss or poor appetite.
Liver
- Discomfort in the upper abdomen on the right side.
- A swollen abdomen.
- A hard lump on the right side just below the rib cage.
- Pain near the right shoulder blade or in the back.
- Jaundice (yellowing of the skin and whites of the eyes).
- Easy bruising or bleeding.
- Unusual tiredness.
- Nausea and vomiting.
- Loss of appetite.
- Weight loss for no known reason.
Ovary
- Vaginal bleeding (particularly if you are past menopause), or discharge from your vagina that is not normal for you.
- Pain or pressure in the pelvic area.
- Abdominal or back pain.
- Bloating.
- Feeling full too quickly, or difficulty eating.
- A change in your bathroom habits, such as more frequent or urgent need to urinate and/or constipation.
Leukemia
- Feeling tired (fatigue)
- Feeling weak
- Feeling cold
- Feeling dizzy or lightheaded
- Shortness of breath
- Paler skin
Non-Hodgkin lymphoma
- swollen lymph nodes, especially in the part of
- fever
- night sweats
- feeling tired
- weight loss.
Uterine
- Vaginal bleeding, or discharge from your vagina that is not normal for you.
- Pain or pressure in the pelvic area.
Brain and other nervous system
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Brain tumor symptoms can include:
- Morning headache or headache that goes away after vomiting
- Seizures
- Vision, hearing, and speech problems
- Loss of appetite
- Frequent nausea and vomiting
- Changes in personality, mood, ability to focus, or behavior
- Weakness, loss of balance, and trouble walking
- Unusual sleepiness
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Spinal cord tumor symptoms can include:
- Back pain or pain that spreads from the back towards the arms or legs
- A change in bowel habits or trouble urinating
- Weakness or numbness in the arms or legs
- Trouble walking
Urinary bladder
- Blood in the urine. This is the most common symptom.
- Having to urinate often.
- Pain while urinating.
- Back pain.
- Pelvic pain.
Esophagus
- Trouble swallowing
- Chest pain
- Weight loss
- Hoarseness
- Chronic cough
- Vomiting
- Bone pain (if cancer has spread to the bone)
Kidney and renal pelvis
- Blood in the urine.
- A lump or swelling in the kidney area or abdomen.

- Feeling tired often.
- Fever that keeps coming back.
- Not feeling like eating.
- Losing weight for no reason that you know of.
- Something blocking your bowels.
- A general feeling of poor health.
Myeloma
- Commonly asymptomatic
- Bone pain, especially in the back or ribs
- Bones that break easily
- Fever for no known reason;
- Frequent infections; bruising or bleeding easily
- Trouble breathing;
- Weakness of the arms or legs
- Feeling very tired.
Stomach
- Commonly asymptomatic
- Poor appetite
- Weight loss (without trying)
- Abdominal (belly) pain
- Vague discomfort in the abdomen, usually above the navel
- Feeling full after eating only a small meal
- Heartburn or indigestion
- Nausea
- Vomiting, with or without blood
- Swelling or fluid build-up in the abdomen
- Blood in the stool
- Feeling tired or weak, as a result of having too few red blood cells (anemia)
- Yellowing of the skin and eyes (jaundice), if the cancer spreads to the liver
Oral cavity and pharynx
- A white or red sore that does not heal on the gums, tongue, or lining of the mouth.
- Swelling in the jaw.
- Unusual bleeding or pain in the mouth.
- A lump or thickening.
- Problems with dentures.
- Trouble breathing or speaking.
- A lump or thickening.
- Trouble chewing or swallowing food.
- A feeling that something is caught in the throat.
- Pain in the throat that won’t go away.
- Pain or ringing in the ears or trouble hearing.
Cervix
- Vaginal bleeding, or discharge from your vagina that is not normal for you.
Melanoma of the skin
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A-B-C-D-Es of melanoma
- Asymmetrical: Does the mole or spot have an irregular shape with two parts that look very different?
- Border: Is the border irregular or jagged?
- Color: Is the color uneven?
- Diameter: Is the mole or spot larger than the size of a pea?
- Evolving: Has the mole or spot changed during the past few weeks or months?
Larynx
- Pain when swallowing.
- Ear pain.
Thyroid
- A lump or swelling on the side of the neck is the most common symptom.
- Having trouble breathing.
- Having trouble swallowing.
- Having a hoarse voice.
Testis
- A lump or enlargement in either testicle
- A feeling of heaviness in the scrotum
- A dull ache in the abdomen or groin
- A sudden collection of fluid in the scrotum
- Pain or discomfort in a testicle or the scrotum
- Enlargement or tenderness of the breasts
- Back pain


3.5.9: Even more Haplorhines (The Apes)
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Figure \(\PageIndex{1}\) - Distribution of gibbons, siamangs, and orangutans. Original blank map from http://d-maps.com/pays.php?num_pay=67&lang= en modified to show distibution of the Southeast Asian great apes.
Figure \(\PageIndex{2}\) - Distribution of chimpanzees and gorillas. Original blank map from http://d-maps.com/carte.php?num_car=728&lang= en modified to show the distribution of the African great apes.
Figure \(\PageIndex{3}\) - Chimpanzee (Pan troglodytes) female and offspring
All apes are members of the superfamily Hominoidea; sometimes they are called hominoids. Hominoids are divided into two families: Hylobatidae, the lesser apes, and Hominidae, the great apes. The Hominids are further divided into three subfamilies: Ponginae, Gorillinae, and Homininae, the latter of which is comprised of two tribes: Panini and Hominini. Which apes belong to each of the classifications will be discussed below.
Common Characteristics
Apes share some common characteristics; note these are in comparison to other primates (Jurmain et al. 2013: 142):
- Generally larger body size
- No tail
- Lower back is shorter and more stable
- Arms longer than legs (except for humans)
- Anatomical differences in shoulder joint that facilitate suspensory feeding and locomotion
- Generally more complex behavior
- More complex brain and enhanced cognitive abilities
- Increased period of infant development and dependency
Hylobatidae
Figure \(\PageIndex{4}\) - Siamang (Symphalangus syndactylus)
Figure \(\PageIndex{5}\) - Female and male white-browed gibbons (Hoolock hoolock)
There is one genera of hylobatids, Hylobates and four subgenera: 1) Bunopithecus , e.g., Western hoolock gibbon, 2) Hylobates , e.g., white-handed gibbon and Bornean white-bearded gibbon, 3) Symphalangus , i.e., siamang, and 4) Nomascus , e.g., black crested gibbon and yellow-cheeked gibbon, many of which are endangered or critically endangered. They are the smallest of the apes, which is why they are sometimes called the “lesser” apes. Hylobatids rarely spend time on the ground. Because they venture so infrequently to the ground they do not have to contend with predators. “Their lifestyle has enabled them to remain petite and agile” (Hamilton 2006 2 : 222). They are true brachiators. Their arms are much longer than their legs and the thumb is attached to the wrist instead of the palm. This enables them to use their hands as hooks as they swing through the trees. They can move quite fast as their arm span allows them to swing over nine feet in a single movement and they can leap up to almost 30 feet in a single bound (Hamilton 2006 2 ). While feeding, hylobatids will use quadrumanous, or four-footed, climbing.
Like some Old World monkeys, hylobatids have ischial callosities, which are for sitting while sleeping (if they do not sit while sleeping, they curl up on their side). They are the only non-human ape that does not build a nest for sleeping. They are well-known for their vocalizations. Monogamous pairs will sing in the morning and evening. The calls can travel over half-a-mile and are used “for territorial defense, maintenance of the pair bond, and general communication” (Paciulli and Neary 2006: 1079). Gibbons may call out 80 to 90% of the day while siamangs only vocalize about 30% of the day. Check out the hylobatids sound gallery from the Gibbons Research Gallery to listen to various vocalizations: http://www.gibbons.de/main/sound.html .
 They exhibit various colorations as well. For example, female white-browed gibbons ( H. hoolock ) are tan while the males are black; a condition referred to as sexual dichromatism, which means that males and females are different colors. Other species have various color fur, e.g., the silvery gibbon has a silver coat while the Kloss gibbon has a black coat and the Mueller’s Bornean gibbon is gray although there is no variation in color between males and females.
Hylobatids are frugivores, although they will eat leaves, flowers and small invertebrates as well. As mentioned previously, they are monogamous and live with their offspring, who may stay with their parents for up to ten years. At some point, offspring “bud off,” or take over part of their parents territory and start their own family groups. Families defend their territories, using vocalizations, chasing, and theatrics such as stick breaking and trashing vegetation; rarely are confrontations physical.
Hominidae
Figure \(\PageIndex{6}\) - Baby bonobo (Pan paniscus)
Orangutans, gorilla, chimpanzees, bonobos, and humans comprise the family Hominidae. Humans will not be covered in this section as Unit 3 is entirely about human evolution. The great apes are the largest primates, with the male eastern lowland gorilla weighing up to 450 pounds. There is extreme sexual dimorphism among orangutans and gorillas; less so in chimpanzees and bonobos. All are quadrupedal, although there are some differences in how quadrupedalism manifests itself. Orangutans exhibit quadrumanous scrambling when arboreal and fist-walking terrestrially while chimpanzees and gorillas are knuckle-walkers. Bonobos also exhibit frequent bipedalism.
Ponginae
Figure \(\PageIndex{7}\) - Bornean orangutan (Pongo pygmaeus)
Figure \(\PageIndex{8}\) - Sumatran orangutan (Pongo abelii)
Both species of pongids are critically endangered: Pongo pygmaeus , the Bornean orangutan, and Pongo abelii , the Sumatran orangutan with dark maroon hair and figure-eight-shaped, hairless faces. Bornean orangutans have ginger-colored hair with light hair on their elongated oval-shaped faces. Bornean orangutans are smaller and fatter than the Sumartran orangs. Second in size only to gorillas, orangutans exhibit sexual dimorphism with the adult males weighing up to 200 pounds with adult females about half that. Mature males have cheek flanges (the bigger the cheek flanges the better as females choose mates based on cheek flange size) and throat pouches with which they make booming calls that alert male rivals and females of their presence. They also have beards and mustaches (Sumatran orangs have longer facial hair than the Bornean orangs). Sexually mature (but not fully grown) males, and occasionally a flanged male, have been known to try to mate with unwilling females, a behavior human researchers have referred to as attempted rape. A study of Sumatran orangs suggests that this is a successful breeding strategy for the unflanged males who sired as many offspring as flanged males without the stress of competing with a fully mature flanged male in an overlapping home range.
Figure \(\PageIndex{9}\) - Fully mature male Bornean orangutan (Pongo pygmaeus)
Orangutans are solitary primates with males and females coming together only to mate. Females may temporarily socialize with other females, but generally live only with one or two of their offspring. Females usually have one offspring at a time with birth spacing of at least six years. Of the non-human apes, female orangs have the longest period of parental investment, lasting up to ten years. Primatologists suggest that this long period of childcare is so that the young have sufficient time to learn “the complexities of life in the rain forest” (Groves 2006: 1787). Like the hylobatids, orangs spend the majority of their time in trees. Since they weigh too much to walk across tree branches to get to another tree, they return to the ground and walk to the next tree. Sumatran orangutans spend less time on the ground than their Bornean counterparts because they are subject to predators such as tigers and cloud leopards whereas the Bornean orangs do not have the same concern.
Orangutans are frugivores, but also eat bird eggs, termites, caterpillars, ants, bark, sap, and a variety of other foods depending on the season. During mast fruiting (a period occurring every two to ten years when many trees fruit at the same time), orangutans gorge themselves with fruit. This allows the orangs to increase their fat stores. Orangutans spend the majority of their day eating, resting, and moving between trees, upwards to 95% of their day. They spend two to three hours in the morning feeding before resting. In late afternoon they travel before preparing their nest for the night.
One of the major differences between the Sumatran and Bornean orangutans has to do with culture. The former manufacture and use tools. They use leaves for multiple purposes, including umbrellas and “toilet paper.” They use branches as flyswatters and in display behavior. They have been observed modifying sticks so that they can be used to collect insects, open seedpods and large fruits, and dig holes. Stacks of leaves are used as padding when holding spiny fruits.
Gorillinae
Figure \(\PageIndex{10}\) - Western Gorilla (Gorilla gorilla gorilla)
The “gentle giant” of the great apes, there are two species of Gorilla : G. gorilla (Western lowland gorilla) and G. beringei (mountain gorilla) and four subspecies: G. g. gorilla , G. g. diehli , G. b. beringei , and G. b. graueri .
Figure \(\PageIndex{11}\) - Male silverback gorilla (G. beringei)
Both of the former are critically endangered while the latter is endangered. Gorillas are sexually dimorphic and typically live in single-male, multi-female groups with a dominant male, over twelve-years-old, who has a band of silver-gray hair on its back, thus is referred to as the silverback; however, there are some multi-male, multi-female groups. Both males and females migrate from their birth groups, although female mountain gorillas tend to migrate more than female lowland gorillas, which helps to avoid inbreeding. Also in the mountain gorillas, males may stay with their natal group. When this occurs, the male is subordinate to the silverback and is called a blackback male. If the silverback dies, one of the blackbacks has the opportunity to become the new silverback. For single-male, multi-female groups, when the silverback dies the females and their offspring may disperse to join other groups or they may stay together until a new silverback transfer. Without a silverback to protect the group, infanticide can occur. The silverback maintains bonds with his females through grooming and togetherness. Conflict between silverbacks involves vocalizations and threat displays, including chest beating; rarely is actual physical conflict involved.
Figure \(\PageIndex{12}\) - Mountain gorilla (G. b. beringei)
Group activity surrounds the silverback who makes all the decisions about when to travel, settling conflict, finding food resources, and defending the group. Blackbacks may assist the silverback with defense. These knuckle-walking primates, spend their days on the ground foraging for food. Females and juveniles sleep in trees, while the dominant male silverback sleeps on the ground. All gorillas are herbivores, although their food focus varies because of their habitats. Mountain gorillas ( G. b. beringei ) are folivores who favor bamboo. Eastern lowland gorillas ( G. b. graueri ) eat seasonally, focusing on fruit when available. They will also eat ants. Western lowland gorillas ( G. gorilla ) also focus on fruit, but also eat herbaceous vegetation, termites, and ants. Because of their diets, the home range of gorillas varies, with Western lowland gorillas having the largest range and mountain gorillas the smallest.
Females usually give birth to one offspring at a time. Infant mortality is high among mountain gorillas (up to 38%) so the mother’s care is particularly important. Males are involved in socialization of infants but do not provide care beyond protection. Infants are weaned after three or four years, providing a decent interval between births and increasing the infant’s chance of survival.
Homininae
Figure \(\PageIndex{13}\) - Adult female and infant wild chimpanzees (Pan troglodytes) feeding on Ficus sur ( figs )
There are two genera of extant hominins: Pan and Homo , with two species of Pan : 1) Pan troglodytes and 2) Pan paniscus , and one species of Homo : Homo sapiens .
The endangered Pan troglodytes , common chimpanzees, and Pan paniscus , bonobos are the apes most genetically similar to humans (98%+). Some researchers (Grove 2001 and Wildman et al. 2003) argue that chimpanzees are so closely related to humans that they should be genus Homo .
Figure \(\PageIndex{14}\) - Pan paniscus ( note the part in the hair )
Chimpanzees live in West and Central Africa, primarily in Gabon and the Democratic Republic of Congo. They inhabit a number of habitats, including, savannas and montane, swamp, and evergreen rainforests. Bonobos are found only in the Democratic Republic of Congo in closed-canopy rainforest.  Male bonobos weigh on average 86 pounds and females 63 pounds. Male chimps are slightly larger at an average of 88 to 132 pounds, and females between 70 and 104 pounds; they are sturdy and strong. As indicated by the average weights, chimpanzees are somewhat larger than bonobos. Chimpanzees have black hair and are born with pale faces that darken as they age. Males and females have beards and prominent ears.  While both species are quadrupedal knuckle-walkers, both can walk bipedally (although bonobos are better bipedal walkers) and bonobos also semi-brachiate.
Chimpanzees live in multi-male, multi-female groups, ranging anywhere from ten to over one hundred individuals. The core of the group is centered on an alpha male along with a small group of bonded males, although in West Africa, some groups appear to be oriented on females. The alpha male and his subordinates use physical force, display behavior, and aggression to control the community. They work together to defend the group’s territory, patrolling and chasing out unfamiliar males. The size of the group’s territory is dependent on the number of males in the group. Even though this small group of males works with the alpha, the dominant chimpanzee must constantly work to maintain his position of power.
Figure \(\PageIndex{15}\) - Mother chimpanzee (Pan troglodytes) and offspring
The strongest bond within chimpanzee social groups is between mothers and their offspring. Females generally have one baby at a time and give birth approximately every five to six years. Even though offspring are weaned by the time they are three-years old, juveniles may stay with their mother and siblings until age five through eight and help with childcare. Juvenile females leave the group at about ten-years-old, except for those groups that are centered on a core group of females. There is quite a bit of movement among group members who do not always spend the day together; they often break off into smaller groups of three to six individuals to forage.
Chimpanzees are omnivores, eating fruits, resin, bark, young leaves, tree seeds, and pith (Orcholl 2006). They incorporate over 300 species of plants in their diet. Some plants seem to be used only for medicinal purposes. Chimpanzees also incorporate animal protein in their diet, which comes from small mammals, including other primates like the colobus monkey, and insects such as termites. Male, and the occasional female, chimpanzees use cooperative techniques to hunt (watch this short video of chimps on the hunt: youtu.be/A1WBs74W4ik). At Mahale Mountain National Park, Tanzania, researchers have observed several occurrences of infanticide after failed hunts. Chimpanzees have been documented making and using spears to hunt and “fishing sticks” to acquire termites and honey (you can check out this short video about spear-wielding chimps: youtu.be/FyGxQq7jSA8). Chimpanzees have other cultural behaviors, including the hand-clasping grooming technique, using wadded up leaves as sponges, and hammers and anvils to break open nuts.
Figure \(\PageIndex{16}\) - Bonobos (Pan paniscus)
Bonobos are sometimes referred to as pygmy chimpanzees because they are slightly smaller and more slender than common chimpanzees, but the weight differences, as mentioned above, are not that great. There is less sexual dimorphism than chimps and about the same as in humans. Bonobos are efficient bipedal walkers and have been documented wading in streams while fishing, walking while carrying an armload of sugar cane, and with arms over each other’s shoulders (Orcholl 2006).
Figure \(\PageIndex{17}\) - Bonobo (Pan paniscus)
Bonobos live in fission-fusion social groups of over twenty individuals. Mother and son bonds are the strongest as sons use their mother’s rank in the social hierarchy as a means to garner favor with other high-ranking females. It is usually the highest-ranking female’s son who is alpha, but the alpha position is much different than that of the chimpanzee. The male and female alphas are almost equally dominant (Orcholl 2006). Unrelated females (juvenile females leave their natal group between ages seven to nine) work together to protect their offspring and secure resources at the expense of males. There is no core group of males that work together---after the alpha male, the hierarchy of males is murky. Also unlike chimpanzees, physical aggression is rarely used to dominate and intimidate.  Females wishing to join a group will use G-G rubbing with the alpha female and intercourse with the alpha male to gain admittance.  The fact that females leave their natal groups prevents incest. Females usually give birth to a single offspring; birth-spacing is from four to six years. Because males do not know which offspring belong to them they do not invest their time in infant care. Mothers are solely responsible for their offspring, which may help to explain why females band together.
Unlike chimpanzees, bonobos do not make and use tools, although captive bonobos have been observed using objects that are made available to them, such as tennis balls as water sponges. They do, however, exhibit emotions such as sympathy and empathy. They seem to respect other individuals’ privacy, never entering another bonobo’s sleeping nest. Like chimps, bonobos use at least one plant for medicinal purposes, specifically a leaf used when they have an intestinal parasite. Bonobos are omnivores, although about 57% of their diet is from fruit. They also eat leaves, flowers, bark, pith, roots, mushrooms, sprouts, and seeds. While bonobos do not hunt, they will opportunistically eat small mammals, insect larvae, earthworms, honey, eggs, and soil (Orcholl 2010 1 ). Finding a food source can set off a flurry of excitement and sexual interaction.
References
- Allen CJ, Evans AV, McDade MC, Schlager N, Mertz LA, Harris MS, et al., editors. Great Apes and Humans: Hominidae. In: Grzimek’s student animal life resource, Vol. 16: Mammals: Vol. 3. Detroit (MI): UXL; 2007. p. 563-577.
- Beckham EC, Cumberlidge N, Regenstein LG. Apes. In: Lerner KL, Lerner BW, editors. The Gale encyclopedia of science, 5th edition, Vol. 5. Farmington Hills (MI): Gale; 2014. p. 278-281.
- Birx HJ. Gorillas. In: Birx HJ, editor. Encyclopedia of anthropology, Vol. 3. Thousand Oaks (CA): SAGE Reference; 2006. p. 1102-1103.
- 1 Cawthon Lang KA. 2005. Primate Factsheets: Gorilla (Gorilla) Behavior. Primate InfoNet [Internet] [cited 2015 Jul 02]. Available from: http://pin.primate.wisc.edu/factsheets/entry/gorilla/behav
- 2 Cawthon Lang KA. 2005. Primate Factsheets: Gorilla (Gorilla) Taxonomy, Morphology, & Ecology. Primate InfoNet [Internet] [cited 2015 Jul 02]. Available from: http://pin.primate.wisc.edu/factsheets/entry/gorilla
- 3 Cawthon Lang KA. 2005. Primate Factsheets: Orangutan (Pongo) Behavior. Primate InfoNet [Internet] [cited 2015 Jul 02]. Available from: http://pin.primate.wisc.edu/factsheets/entry/orangutan/behav
- 4 Cawthon Lang KA. 2005. Primate Factsheets: Orangutan (Pongo) Taxonomy, Morphology, & Ecology. Primate InfoNet [Internet] [cited 2015 Jul 02]. Available from: http://pin.primate.wisc.edu/factsheets/entry/orangutan
- Cawthon Lang KA. 2006. Primate Factsheets: Chimpanzee (Pan troglodytes) Taxonomy, Morphology, & Ecology. Primate InfoNet [Internet] [cited 2015 Jul 02]. Available from: http://pin.primate.wisc.edu/factsheets/entry/chimpanzee
- 1 Cawthon Lang KA. 2010. Primate Factsheets: Bonobo (Pan paniscus) Behavior. Primate InfoNet [Internet] [cited 2015 Jul 02]. Available from: http://pin.primate.wisc.edu/factsheets/entry/bonobo/behav
- 2 Cawthon Lang KA. 2010. Primate Factsheets: Bonobo (Pan paniscus) Taxonomy, Morphology, & Ecology. Primate InfoNet [Internet] [cited 2015 Jul 02]. Available from: http://pin.primate.wisc.edu/factsheets/entry/bonobo/taxon
- Cumberlidge N. Gorillas. In: Lerner KL, Lerner BW, editors. The Gale encyclopedia of science, 5th edition, Vol. 4. Farmington Hills (MI): Gale; 2014. p. 2023-2024.
- Groves C. 2001. Primate taxonomy. Washington (DC): Smithsonian Institute Press.
- Groves C. Orangutans. In: Birx HJ, editor. Encyclopedia of anthropology, Vol. 4. Thousand Oaks (CA): SAGE Reference; 2006. p. 1785-1787.
- 1 Hamilton, GS. Apes, Lesser. In: Birx, HJ, editor. Encyclopedia of anthropology, Vol. 1. Thousand Oaks (CA): SAGE Reference; 2006. p. 220-221.
- 2 Hamilton, GS. Apes, Lesser. In: Birx, HJ, editor. Encyclopedia of anthropology, Vol. 1. Thousand Oaks (CA): SAGE Reference; 2006. p. 221-222.
- [ICUN] Internation Union for Conservation of Nature and Natural Resources [Internet]. 2015. The ICUN red list of threatened species [cited 2015 Jul 02]. Available from: www.icunredlist.org/
- Jurmain R, Kilgore L, Trevathan W. 2013. Essentials of physical anthropology, 4th edition. Belmont (CA): Wadsworth, Cengage Learning.
- O’Neill D. 1998-2014. Apes. Behavioral Sciences Department, Palomar College [Internet] [cited 2015 Jul 01]. Available from: anthro.palomar.edu/primate/prim_7.htm
- 1 Orcholl JL. Bonobos. In: Birx HJ, editor. Encyclopedia of anthropology, Vol. 3. Thousand Oaks (CA): SAGE Reference; 2006. p. 389-392.
- 2 Orcholl JL. Chimpanzees. In: Birx HJ, editor. Encyclopedia of anthropology, Vol. 3. Thousand Oaks (CA): SAGE Reference; 2006. p. 500-505.
- Paciulli LM, Neary JL. Gibbons. In: Birx HJ, editor. Encyclopedia of anthropology, Vol. 3. Thousand Oaks (CA): SAGE Reference; 2006. p. 1078-1079.
- Richman K. Chimpanzees. In: Lerner KL, Lerner BL, editors. The Gale encyclopedia of science, 5th edition, Vol. 2. Farmington Hills (MI): Gale; 2014. p. 905-910.
- Wildman DE, Uddin M, Guozhen L, Grossman LI, Goodman M. 2003. Implications of natural selection in shaping 99.4% nonsynonymous DNA identity between humans and chimpanzees: enlarging genus Homo.


2.6: Bibliography
Ainsworth, Shaaron E., Peter A. Bibby, and David J. Wood. “Information Technology and Multiple Representations: New Opportunities – New Problems.” Journal of Information Technology for Teacher Education 6, no. 1 (March 1, 1997): 93–105. https://doi.org/10.1080/14759399700200006 .
Chi, Michelene T. H., Nicholas De Leeuw, Mei-Hung Chiu, and Christian Lavancher. “Eliciting Self-Explanations Improves Understanding.” Cognitive Science 18, no. 3 (July 1, 1994): 439–77. doi.org/10.1016/0364-0213(94)90016-7 .
Davis, Elizabeth A. “Scaffolding Students’ Knowledge Integration: Prompts for Reflection in KIE.” International Journal of Science Education 22, no. 8 (August 1, 2000): 819–37. https://doi.org/10.1080/095006900412293 .
Harrison, Allan G., and David F. Treagust. “Modelling in Science Lessons: Are There Better Ways to Learn With Models?” School Science and Mathematics 98, no. 8 (1998): 420–29. https://doi.org/10.1111/j.1949-8594.1998.tb17434.x .
Hui Li1<EMAIL_ADDRESS>, and Gengsheng Xiao1. “An Empirical Study on Productive Vocabulary Acquisition Under Hypertext Reading.” International Journal of Emerging Technologies in Learning 13, no. 12 (December 2018): 109–22. https://doi.org/10.3991/ijet.v13i12.8846 .
“Intelligence, Dual Coding Theory, and the Brain | Elsevier Enhanced Reader.” Accessed June 16, 2019. https://doi.org/10.1016/j.intell.2014.09.002 .
Kozma, Robert B. “Learning with Media.” Review of Educational Research 61, no. 2 (June 1, 1991): 179–211. https://doi.org/10.3102/00346543061002179 .
Larkin, Jill H., and Herbert A. Simon. “Why a Diagram Is (Sometimes) Worth Ten Thousand Words.” Cognitive Science 11, no. 1 (January 1, 1987): 65–100. https://doi.org/10.1016/S0364-0213(87)80026-5 .
Mayer, Richard E. “Multimedia Learning.” In Psychology of Learning and Motivation , 41:85–139. Academic Press, 2002. https://doi.org/10.1016/S0079-7421(02)80005-6 .
“Multimedia Learning: Are We Asking the Right Questions?” Educational Psychologist 32, no. 1 (January 1, 1997): 1–19. https://doi.org/10.1207/s15326985ep3201_1 .
Michas, Irene C., and Dianne C. Berry. “Learning a Procedural Task: Effectiveness of Multimedia Presentations.” Applied Cognitive Psychology 14, no. 6 (2000): 555–75. https://doi.org/10.1002/1099-0720(200011/12)14:6<555::AID-ACP677>3.0.CO;2-4 .
Ng, Yee Fai, Kwan Kit Chan, Huey Lei, Phoebe Mok, and Shing Yu Leung. “Pedagogy and Innovation in Science Education: A Case Study of an Experiential Learning Science Undergraduate Course.” The European Journal of Social & Behavioural Sciences; Nicosia 25, no. 2 (April 2019): 2910–26. http://dx.doi.org/10.15405/ejsbs.254 .
Paivio, Allan. “Dual Coding Theory, Word Abstractness, and Emotion: A Critical Review of Kousta et Al. (2011).” Journal of Experimental Psychology: General 142, no. 1 (February 2013): 282–87. http://dx.doi.org/10.1037/a0027004 .
“Mental Imagery in Associative Learning and Memory.” Psychological Review 76, no. 3 (May 1969): 241–63. http://dx.doi.org/10.1037/h0027272 .
Reiser, Brian J. “Scaffolding Complex Learning: The Mechanisms of Structuring and Problematizing Student Work.” Journal of the Learning Sciences 13, no. 3 (July 1, 2004): 273–304. https://doi.org/10.1207/s15327809jls1303_2 .
Shorb, J. M.; Moore, J. W. The ChemPaths Student Portal: Making an Online Textbook More than a Book Online. In Enhancing Learning with Online Resources, Social Networking, and Digital Libraries ; ACS Symposium Series; American Chemical Society, 2010; Vol. 1060, pp 283–308. https://doi.org/10.1021/bk-2010-1060.ch015 .
Wu, Hsin-Kai, and Priti Shah. “Exploring Visuospatial Thinking in Chemistry Learning.” Science Education 88, no. 3 (2004): 465–92. https://doi.org/10.1002/sce.10126 .
Vörös, Zsofia, Jean-François Rouet, and Csaba Pléh. “Effect of High-Level Content Organizers on Hypertext Learning.” Computers in Human Behavior , 2009 Fifth International Conference on Intelligent Computing, 27, no. 5 (September 1, 2011): 2047–55. https://doi.org/10.1016/j.chb.2011.04.005 .
Yang, S. C. Synergy of Constructivism and Hypermedia from Three Constructivist Perspectives— Social, Semiotic, and Cognitive. Journal of Educational Computing Research 2001 , 24 (4), 321–361. https://doi.org/10.2190/JW76-7C6V-LUER-LCAQ .


23.9: Sample problems and solutions
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Exercise \(\PageIndex{1}\)
In the 1950s, the Royal Canadian Air Force developed a jet airplane called the Avro Arrow. This jet reached a speed of mach 1.9 ( \(652\text{ms}^{-1}\) ), and was considered one of the most advanced airplanes that existed at the time. Suppose that the Avro Arrow is traveling at a velocity of \(v = 652\text{ms}^{-1}\) above the Sout Pole through Earth’s vertical magnetic field, \(B = 5.2\times 10^{-5}\text{T}\) , as shown in Figure \(\PageIndex{1}\). If the Avro Arrow had a wingspan of \(l = 15\text{m}\) , determine the induced voltage across its wings.
- Answer
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This is identical to the motional emf that is generated by a bar moving in a magnetic field. As the airplane moves as illustrated (towards the left, in an upwards magnetic field), the electrons in the wing of the airplane will be pushed into the page. Eventually, the electric field from the electrons will prevent further electrons from accumulating at that side of the wing, and there will be a constant (Hall) voltage, \(\Delta V\) , across the wing tips. This will happen when the magnetic and electric force are equal and opposite:
\[\begin{aligned} qvB &= qE = q\frac{\Delta V}{L}\end{aligned}\]
where \(L\) is the wingspan of the airplane. The induced potential is thus given by:
\[\begin{aligned} \Delta V = BLv = (5.2\times 10^{-5}\text{T})(15\text{m})(652\text{ms}^{-1})=0.51\text{V}\end{aligned}\]
Exercise \(\PageIndex{2}\)
A generator is made of \(N\) circular loops of radius, \(R=0.3\text{m}\) , rotating at a frequency of \(f=60\text{Hz}\) , in a uniform magnetic field, \(B=0.1\text{T}\) . How many coils must the generator have in order for it to produce an alternating voltage with a maximum amplitude of \(\Delta V =110\text{V}\) .
- Answer
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The voltage produced by a generator is given by:
\[\begin{aligned} \Delta V&=NAB\omega\sin(\omega t)\end{aligned}\]
and the angular frequency is given by \(\omega = 2\pi f\) . The number of required coils is thus:
\[\begin{aligned} N=\frac{\Delta V}{AB\omega}=\frac{\Delta V}{\pi R^2B2\pi f}=\frac{(110\text{V})}{2\pi^2(0.3\text{m})^2(0.1\text{T})(60\text{Hz})}=10.3\end{aligned}\]
Thus, one requires 10 loops in the coil to generate the desired voltage.


8.8: Editing Your Paper
The next step after revising the content is editing. When you edit, examine the surface features of your text: spelling, grammar, spacing, and punctuation . It takes time, so be sure to budget time into the writing process to complete additional edits after revising. It is also very easy to read past a mistake, so set your paper aside for at least a few hours, if not a day or more, so your mind can rest. If you need additional proofreading help, ask a reliable friend, classmate, or peer tutor to make a final pass on your paper to look for anything you missed.
Here are a few tips about readers:
- They don’t notice correct spelling, but they do notice misspellings. They won’t cheer when you use there, their, and they’re correctly, but they will notice when you do not.
- They look past your sentences to get to your ideas – unless the sentences are awkward, poorly constructed, and frustrating to read.
- They notice when every sentence has the same rhythm as every other sentence, with no variety.
- The accumulation of errors distracts the reader from your argument and suggests that you didn’t put enough care into your writing.
Student Tip
Spell and Grammar Check
Spell and grammar checks can be helpful, but you must review them carefully. Your computer may be programmed to identify problem words, but it is not always correct, so don’t rely on it. A computer cannot consider context and meaning. For example, if the spellchecker identifies a word that is misspelled and provides alternatives, you might end up choosing a word that you never intended, even though it is spelled correctly. This can change the meaning of your sentence. Spellcheck can also miss misspelled words that are correct spellings of a different word: e.g., form versus from. Spellcheck may also make grammatical suggestions such as semi-colons and hyphens that do not necessarily fit your sentence structure.
Attribution statement
Remixed with our own original content and adapted, with editorial changes, from:
Writing for Success 1st Canadian Edition by Tara Horkoff is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted. Download for free at: opentextbc.ca/writingforsuccess/


4.6: Cyclic Ethers - Epoxides
After completing this section, you should be able to
- write an equation to describe the industrial preparation of ethylene oxide.
- list two important industrial uses of ethylene oxide.
- write an equation to describe the normal laboratory preparation of an epoxide.
- identify the epoxide produced from the reaction of a given alkene with a peroxyacid.
- identify the alkene, the reagent, or both, needed to prepare a given epoxide.
- write an equation to describe the preparation of an epoxide from an alkene via a halohydrin.
Make certain that you can define, and use in context, the key term below.
- epoxide (oxirane)
Epoxides (also known as oxiranes ) are three-membered ring structures in which one of the vertices is an oxygen and the other two are carbons. Epoxides behave differently than other ethers due to the strain created by the three-membered ring.
The most important and simplest epoxide is ethylene oxide which is prepared on an industrial scale by catalytic oxidation of ethylene by air. Ethylene oxide is used as an important chemical feedstock in the manufacturing of ethylene glycol, which is used as antifreeze, liquid coolant and solvent. In turn, ethylene glycol is used in the production of polyester and polyethylene terephthalate (PET) the raw material for plastic bottles.
Nomenclature of Epoxides
The name ethylene oxide is not systematic but common. Epoxides are systematically named as an oxirane ring system much like the other cyclic ethers discussed in Section 4. 2 . The oxygen is numbered in the 1 position.
Synthesis of Epoxides
As discussed in CHEM 231, epoxides are typically prepared by the reaction of an alkene and a peroxycarboxylic acid (RCO 3 H), such as meta -chloroperbenzoic acid (MCPBA). The peroxycarboxylic acid has the unique property of having an electropositive oxygen atom on the CO 3 H group. The reaction is initiated by the electrophilic oxygen atom reacting with the nucleophilic carbon-carbon double bond. The mechanism involves a concerted reaction with a four-part, circular transition state. The result is that the originally electropositive oxygen atom ends up in the oxacyclopropane ring and the CO 3 H group becomes CO 2 H.
General Reaction
Stereochemical Consideration
The oxygen addition to the alkene is a syn addition and is stereospecific. The substituents of a cis -alkene will appear in the cis configuration on the epoxide ring. Likewise, Substituents of a trans -alkene will appear in the trans configuration on the epoxide ring. During this reaction the sp 2 hybridized carbons of the alkene are converted to sp 3 hybridized carbons in the epoxide. Thus, there is the possibility of two new chiral carbons forming in the epoxide product. In most cases, epoxidation of an alkene will product a mixture of enantiomers in the product, due to the electrophilic oxygen being able to attack from above or below the plane of the alkene. One major exception is the epoxidation of symmetrical cis-alkene which produces a meso compound product.
Treatment of an alkene with X 2 & H 2 O creates a halohydrin. When a halohydrin is treated with a base the alcohol is deprotonated to from an alkoxide. This causes an intramolecular Williamson ether synthesis to produce an epoxide along with the elimination of HX. Note, that this reaction generally forms a mixture of enantiomeric products unless a meso compound is produced.
1) What reagents would you use to perform the following transformation?
2) Predict the products of the following reactions:
3) Predict the product of the following reaction. Be sure to include proper stereochemistry.
- Answer
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1) Lindlar's catalyst reduces alkynes to cis/Z alkenes. This stereochemistry is retained after epoxidation.
2)
3)


3.1: What are Ban-the-Box Laws?
View of outreach materials are seen at a press conference for a Ban The Box Petition delivery to the White House on Oct. 26, 2015. Bloomberg News.
Photographer: Larry French/Getty Images for ColorOfChange.org
Ban the Box
Dozens of cities and states restrict employers from asking job applicants about criminal convictions through “ban-the-box” laws.
Ban the box refers to the check box on employment applications asking whether the candidate has ever been convicted of a crime. Ban-the-box laws require hiring managers to put off asking about a candidate’s criminal history until after an interview has been conducted or a provisional job offer has been extended.
Ban-the-box laws prohibit employers from asking about a person's criminal history on a job application.
By Sachi Clements, Attorney
If you've been reading the news lately, you might have heard of something called a "ban-thebox" law. More than a dozen states and the District of Columbia, as well as many ciites, have passed these types of laws in the past few years.
Ban-the-box laws help the estimated 30% of adults with a criminal past get a fair shot at finding work, by encouraging employers to assess their qualifications and skills before denying employment.
History of Ban-the-Box Laws
At some point in their lives, most people have filled out a standard job application with a set of common questions. One of those questions is: "Have you ever been convicted of a crime? Check yes or no." Many applicants reluctantly check "yes," knowing that it often means the end of the application process for them.
Employers often used the question to weed out applicants with a criminal record, without considering the specifics of the crime, how long ago it happened, or what the applicants have been up to since then.
Not surprisingly, those with a criminal past face high unemployment rates. Studies have shown that lack of employment leads to high recidivism rates. In other words, ex-offenders who are out of work are more likely to commit further crimes.
There's also a concern of racial discrimination. One type of discrimination, called disparate impact discrimination, happens when a seemingly neutral policy disproportionately affects members of a particular race.
Because African American and Latino men are arrested and convicted at disproportionately higher rates than Caucasian men, asking about criminal records has a disproportionate impact on them.
What Does a Ban-the-Box Law Do?
All ban-the-box laws prohibit employers from asking applicants about criminal history on an initial job application. However, some go further, requiring employers to wait until after they have conducted an interview or made a conditional offer of employment before asking about criminal history.
A few laws also impose additional requirements. For example, in California, employers must engage in a multi-factored individual analysis of whether the criminal record justifies denying employment. And, if the employer decides to deny employment based on a criminal record, it must provide the applicant with notice and an opportunity to provide mitigating evidence that lessens the impact of the conviction.
Most ban-the-box laws contain exemptions for security-related jobs and those that require working with children, vulnerable adults, and the elderly.
Which Employers Must Comply With Ban-the-Box Laws?
To date, there is no federal ban-the-box law; these are laws being passed by states and cities. Initially, these laws applied to government employers only. However, more states and cities are passing laws that apply to government and private employers alike.
States With Ban the Box Laws
Currently, 15 states (and the District of Columbia) have ban-the-box laws that apply to private employers. They are:
- California
- Colorado
- Connecticut
- Hawaii
- Illinois
- Maine
- Maryland
- Massachusetts
- Minnesota
- New Jersey
- New Mexico
- Oregon
- Rhode Island
- Vermont, and
- Washington.
More than 35 states have laws that apply to government employers. To learn about your state's rules on arrest and conviction records, see our records during employment. state articles on considering criminal
Several cities have their own laws, especially ones in major metropolitan areas. To learn whether your city has one of these laws, contact your local government.
What Other Laws Should Employers Be Aware Of?
Even in states that don't have ban-the-box laws, a rigid practice of asking about criminal history and denying employment can violate federal anti-discrimination laws.
As mentioned above, categorically denying employment to applicants within criminal records can have a disproportionate impact on certain racial groups. The Equal Employment Opportunity Commission (EEOC) has warned against this practice, issuing guidelines to follow in order to avoid discrimination. It includes conducting an individualized analysis considering factors such as:
- the nature of the job
- the severity of the offense, and
- how much time has passed.
Some states have additional rules that apply to certain types of criminal records. For example, many states prohibit employers from considering sealed or expunged criminal records, arrests that didn't lead to conviction, or juvenile records. To learn more, select your state from our state articles on considering criminal records during employment.
Contact an Employment Lawyer
Because this is a complex area of the law, and the rules vary widely by location, it's a good idea to consult with a lawyer about your practices.
SOURCE: "What is a Ban the Box Law?" , NOLO website, May 25, 2022.
Interactive Website
To learn more about this topic and to see what states are required to be in compliance with Ban the Box laws, go to the Accurate Ban the Box website .


7: Volume and Measure
I. Our theory of set families leads quite naturally to a generalization of metric spaces. As we know, in any such space \((S, \rho),\) there is a family \(\mathcal{G}\) of open sets, and a family \(\mathcal{F}\) of all closed sets. In Chapter 3, §12, we derived the following two properties.
(i) \(\mathcal{G}\) is closed under any (even uncountable) unions and under finite intersections (Chapter 3, §12, Theorem 2). Moreover,
\[\emptyset \in \mathcal{G} \text { and } S \in \mathcal{G}.\]
(ii) \(\mathcal{F}\) has these properties, with "unions" and "intersections" interchanged (Chapter 3, §12, Theorem 3). Moreover, by definition,
\[A \in \mathcal{F} \text { iff }-A \in \mathcal{G}.\]
Now, quite often, it is not so important to have distances (i.e., a metric) defined in \(S,\) but rather to single out two set families, \(\mathcal{G}\) and \(\mathcal{F},\) with properties (i) and (ii), in a suitable manner. For examples, see Problems 1 to 4 below. Once \(\mathcal{G}\) and \(\mathcal{F}\) are given, one does not need a metric to define such notions as continuity, limits, etc. (See Problems 2 and 3.) This leads us to the following definition.