13.7: The Major Channels of Management Communication Are Talking, Listening, Reading, and Writing
- Know why talking, listening, reading, and writing are vital to managing effectively.
The major channels of managerial communication displayed in Figure 13.5.1 are talking, listening, reading, and writing. Among these, talking is the predominant communication method, but as e-mail and texting increase, reading and writing are also increasing. Managers across industries, according to Deirdre Borden, spend about 75% of their time in verbal interaction. Those daily interactions include the following.
One-on-One Conversations
Increasingly, managers find that information is passed orally, often face-to-face in offices, hallways, conference rooms, cafeterias, restrooms, athletic facilities, parking lots, and dozens of other venues. An enormous amount of information is exchanged, validated, confirmed, and passed back and forth under highly informal circumstances.
Telephone Conversations
Managers spend an astounding amount of time on the telephone these days. Curiously, the amount of time per telephone call is decreasing, but the number of calls per day is increasing. With the nearly universal availability of cellular and satellite telephone service, very few people are out of reach of the office for very long. The decision to switch off a cellular telephone, in fact, is now considered a decision in favor of work-life balance.
Video Teleconferencing
Bridging time zones as well as cultures, videoconferencing facilities make direct conversations with employees, colleagues, customers, and business partners across the nation or around the world a simple matter. Carrier Corporation, the air-conditioning manufacturer, is now typical of firms using desktop videoconferencing to conduct everything from staff meetings to technical training. Engineers at Carrier’s Farmington, Connecticut, headquarters can hook up with service managers in branch offices thousands of miles away to explain new product developments, demonstrate repair techniques, and update field staff on matters that would, just recently, have required extensive travel or expensive, broadcast-quality television programming. Their exchanges are informal, conversational, and not much different than if the people were in the same room (Ziegler, 1994).
Presentations to Small Groups
Managers frequently find themselves making formal and informal presentations to groups of three to eight people for many different reasons: passing along information given to them by executives, reviewing the status of projects in process, and explaining changes in everything from working schedules to organizational goals. Such presentations are sometimes supported by overhead transparencies or printed outlines, but they are oral in nature and retain much of the conversational character of one-to-one conversations.
Public Speaking to Larger Audiences
Most managers cannot escape the periodic requirement to speak to larger audiences of several dozen or, perhaps, several hundred people. Such presentations are usually more formal in structure and are often supported by PowerPoint or Prezi software that can deliver data from text files, graphics, photos, and even motion clips from streaming video. Despite the more formal atmosphere and sophisticated audio-visual support systems, such presentations still involve one manager talking to others, framing, shaping, and passing information to an audience.
A series of scientific studies, beginning with Rankin (1952), Nichols and Stevens (1957), and Wolvin and Coakley (1982), confirm: most managers spend the largest portion of their day talking and listening. Werner’s (1975) thesis, in fact, found that North American adults spend more than 78% of their communication time either talking or listening to others who are talking.
According to Werner and others who study the communication habits of postmodern business organizations, managers are involved in more than just speeches and presentations from the dais or teleconference podium. They spend their days in meetings, on the telephone, conducting interviews, giving tours, supervising informal visits to their facilities, and at a wide variety of social events (Kotter, 1999).
Each of these activities may look to some managers like an obligation imposed by the job. Shrewd managers see them as opportunities to hear what others are thinking, to gather information informally from the grapevine, to listen in on office gossip, to pass along viewpoints that haven’t yet made their way to the more formal channels of communication, or to catch up with a colleague or friend in a more relaxed setting. No matter what the intention of each manager who engages in these activities, the information they produce and the insight that follows from them can be put to work the same day to achieve organizational and personal objectives. “To understand why effective managers behave as they do,” writes Kotter, “it is essential first to recognize two fundamental challenges and dilemmas found in most of their jobs.” Managers must first figure out what to do, despite an enormous amount of potentially relevant information (along with much that is not), and then they must get things done “through a large and diverse group of people despite having little direct control over most of them” (Berger & Luckmann, 1966).
The Role of Writing
Writing plays an important role in the life of any organization. In some organizations, it becomes more important than in others. At Procter & Gamble, for example, brand managers cannot raise a work-related issue in a team meeting unless the ideas are first circulated in writing. For P&G managers, this approach means explaining their ideas in explicit detail in a standard one-to-three-page memo, complete with background, financial discussion, implementation details, and justification for the ideas proposed.
Other organizations are more oral in their traditions—3M Canada is a “spoken” organization—but the fact remains: the most important projects, decisions, and ideas end up in writing. Writing also provides analysis, justification, documentation, and analytic discipline, particularly as managers approach important decisions that will affect the profitability and strategic direction of the company.
Writing is a career sifter. If managers demonstrate their inability to put ideas on paper clearly and unambiguously, they’re not likely to last. Stories of bad writers who’ve been shown the door early in their careers are legion. Managers’ principal objective, at least during the first few years of their careers, is to keep their name out of such stories. Remember: those most likely to notice the quality and skill in managers’ written documents are the very people most likely to matter to managers’ future.
Managers do most of their own writing and editing. The days when managers could lean back and thoughtfully dictate a letter or memo to a skilled secretarial assistant are mostly gone. Some senior executives know how efficient dictation can be, especially with a top-notch administrative assistant taking shorthand, but how many managers have that advantage today? Very few, mostly because buying a computer and printer is substantially cheaper than hiring another employee. Managers at all levels of most organizations draft, review, edit, and dispatch their own correspondence, reports, and proposals.
Documents take on lives of their own. Once it’s gone from the manager’s desk, it isn’t theirs anymore. When they sign a letter and put it in the mail, it’s no longer their letter—it’s the property of the person or organization it was sent to. As a result, the recipient is free to do as she sees fit with the writing, including using it against the sender. If the ideas are ill-considered or not well expressed, others in the organization who are not especially sympathetic to the manager’s views may head for the copy machine with the manager’s work in hand. The advice for managers is simple: do not mail the first draft, and do not ever sign your name to a document you are not proud of.
Communication Is Invention
Without question, communication is a process of invention. Managers literally create meaning through communication. A company, for example, is not in default until a team of auditors sits down to examine the books and review the matter. Only after extended discussion do the accountants conclude that the company is, in fact, in default. It is their discussion that creates the outcome. Until that point, default was simply one of many possibilities.
The fact is managers create meaning through communication. It is largely through discussion and verbal exchange—often heated and passionate—that managers decide who they wish to be: market leaders, takeover artists, innovators, or defenders of the economy. It is only through communication that meaning is created for shareholders, employees, customers, and others. Those long, detailed, and intense discussions determine how much the company will declare in dividends this year, whether the company is willing to risk a strike or labor action, and how soon to roll out the new product line customers are asking for. Additionally, it is important to note that managers usually figure things out by talking about them as much as they talk about the things they have already figured out. Talk serves as a wonderful palliative: justifying, analyzing, dissecting, reassuring, and analyzing the events that confront managers each day.
Information Is Socially Constructed
If we are to understand just how important human discourse is in the life of a business, several points seem especially important.
Information is created, shared, and interpreted by people. Meaning is a truly human phenomenon. An issue is only important if people think it is. Facts are facts only if we can agree upon their definition. Perceptions and assumptions are as important as truth itself in a discussion about what a manager should do next (Larkin & Larkin, 1994). Information never speaks for itself. It is not uncommon for a manager to rise to address a group of her colleagues and say, “The numbers speak for themselves.” Frankly, the numbers never speak for themselves. They almost always require some interpretation, some sort of explanation or context. Do not assume that others see the facts in the same way managers do, and never assume that what is seen is the truth. Others may see the same facts or evidence but not reach the same conclusions. Few things in life are self-explanatory.
Context always drives meaning. The backdrop to a message is paramount to the listener, viewer, or reader in reaching a reasonable, rational conclusion about what she sees and hears. What’s in the news these days as we take up this subject? What moment in history do we occupy? What related or relevant information is under consideration as this new message arrives? We cannot derive meaning from one message without considering everything else surrounding it.
A messenger always accompanies a message. It is difficult to separate a message from its messenger. We often want to react more to the source of the information than we do to the information itself. That’s natural and entirely normal. People speak for a reason, and we often judge their reasons for speaking before analyzing what they have to say. Keep in mind that, in every organization, message recipients will judge the value, power, purpose, intent, and outcomes of the messages they receive by the source of those messages as much as by the content and intent of the messages themselves. If the messages managers send are to have the impact hoped for, they must come from a source the receiver knows, respects, and understands.
Managers’ Greatest Challenge
Every manager knows communication is vital, but every manager also seems to “know” that she is great at it. Managers’ greatest challenge is admitting flaws in their skill set and working tirelessly to improve them. First, managers must admit to the flaws.
Larkin and Larkin write, “Deep down, managers believe they are communicating effectively. In ten years of management consulting, we have never had a manager say to us that he or she was a poor communicator. They admit to the occasional screw-up, but overall, everyone, without exception, believes he or she is basically a good communicator” (Larkin & Larkin, 1994).
Managers’ Task as Professionals
As a professional manager, the first task is recognizing and understanding one’s strengths and weaknesses as a communicator. Until these communication tasks at which one is most and least skilled are identified, there will be little opportunity for improvement and advancement.
Foremost among managers’ goals should be to improve existing skills. Improve one’s ability to do what is done best. Be alert to opportunities, however, to develop new skills. Managers should add to their inventory of abilities to keep themselves employable and promotable.
Two other suggestions come to mind for improving managers’ professional standing. First, acquire a knowledge base that will work for the years ahead. That means speaking with and listening to other professionals in their company, industry, and community. They should be alert to trends that could affect their company’s products and services and their own future.
It also means reading. Managers should read at least one national newspaper each day, such as the Wall Street Journal , the New York Time s, or the Financial Times , as well as a local newspaper. Their reading should include weekly news magazines, such as U.S. News & World Report, Bloomberg’s Business Week , and the Economist . Subscribe to monthly magazines such as Fast Company and Fortune . And they should read at least one new hardcover title a month. A dozen books each year is the bare minimum on which one should depend for new ideas, insights, and managerial guidance.
Managers’ final challenge is to develop the confidence needed to succeed as a manager, particularly under conditions of uncertainty, change, and challenge.
ETHICS IN PRACTICE
Disney and H-1B Visas
On January 30, 2015, The Walt Disney Company laid off 250 of its IT workers. In a letter to the laid-off workers, Disney outlined the conditions for receipt of a “stay bonus,” which would entitle each worker to a lump-sum payment of 10% of their annual salary.
Of course, there was a catch. Only those workers who trained their replacements over a 90-day period would receive the bonus. One American worker in his 40s who agreed to Disney’s severance terms explained how it worked in action:
“The first 30 days was all capturing what I did. The next 30 days, they worked side by side with me, and the last 30 days, they took over my job completely. I had to make sure they were doing my job correctly.”
To outside observers, this added insult to injury. It was bad enough to replace U.S. workers with cheaper, foreign labor. But to ask, let alone strong-arm, the laid-off workers into training their replacements seemed a bit much.
However unfortunate, layoffs are commonplace. But this was different. From the timing to the apparent neglect of employee pride, the sequence of events struck a nerve. For many, the issue was simple, and Disney’s actions seemed wrong at a visceral level. As criticism mounted, it became clear that this story would develop legs. Disney had a problem.
For David Powers and Leo Perrero, each a 10-year information technology (IT) veteran at Disney, the invitation came from a vice president of the company. It had to be good news, the men thought. After all, they were not far removed from strong performance reviews—perhaps they would be awarded performance bonuses. Well, not exactly. Leo Perrero, one of the summoned workers, explains what happened next.
“I’m in the room with about two-dozen people, and very shortly thereafter, an executive delivers the news that all of our jobs are ending in 90 days, and that we have 90 days to train our replacements or we won’t get a bonus that we’ve been offered.”

These layoffs and the hiring of foreign workers under the H-1B program lay at the center of this issue. Initially introduced by the Immigration and Nationality Act of 1965, subsequent modifications produced the current iteration of the H-1B visa program in 1990. Importantly, at that time, the United States faced a shortage of skilled workers necessary to fill highly technical jobs. Enter the H-1B visa program as the solution. This program permits U.S. employers to temporarily employ foreign workers in highly specialized occupations. “Specialty occupations” are defined as those in the fields of architecture, engineering, mathematics, science, medicine, and others that require technical and skilled expertise.
Congress limited the number of H-1B visas issued to 85,000 per year. That total is divided into two subcategories: “65,000 new H-1B visas issued for overseas workers in professional or specialty occupation positions, and an additional 20,000 visas available for those with an advanced degree from a U.S. academic institution.” Further, foreign workers are not able to apply for an H-1B visa. Instead, a U.S. employer must petition on their behalf no earlier than six months before the starting date of employment.
To be eligible for an employer to apply a foreign worker for an H-1B visa, the worker needed to meet certain requirements, such as an employee-employer relationship with the petitioning U.S. employer and a position in a specialty occupation related to the employee’s field of study, where the employee must meet one of the following criteria: a bachelor’s degree or the foreign equivalent of a bachelor’s degree, a degree that is standard for the position, or previous qualified experience within the specialty occupation.
If approved, the initial term of the visa is three years, which may be extended an additional three years. While residing in the United States on an H-1B visa, a worker may apply to become a permanent resident and receive a green card, which would entitle the worker to remain indefinitely.
U.S. employers are required to file a Labor Condition Application (LCA) on behalf of each foreign worker they seek to employ. That application must be approved by the U.S. Department of Labor. The LCA requires the employer to assure that the foreign worker will be paid a wage and be provided working conditions and benefits that meet or exceed the local prevailing market and to assure that the foreign worker will not displace a U.S. worker in the employer’s workforce.
Given these representations, U.S. employers have increasingly been criticized for abuse of the H-1B program. Most significantly, there is rising sentiment that U.S. employers are displacing domestic workers in favor of cheaper foreign labor. Research indicates that a U.S. worker’s salary for these specialty occupations often exceeds $100,000, while that of a foreign worker is roughly $62,000 for the very same job. The latter figure is telling, since $60,000 is the threshold below which a salary would trigger a penalty.
Disney faced huge backlash and negative press because of the layoffs and hiring of foreign workers. Because of this, Disney had communication challenges, both internally and externally.
Disney executives framed the layoffs as part of a larger plan of reorganization intended to enable its IT division to focus on driving innovation. Walt Disney World spokesperson Jacquee Wahler gave the following explanation:
“We have restructured our global technology organization to significantly increase our cast member focus on future innovation and new capabilities , and are continuing to work with leading technical firms to maintain our existing systems as needed.” (Italics added for emphasis.)
That statement is consistent with a leaked memo drafted by Disney Parks and Resort CIO Tilak Mandadi, which he sent to select employees on November 10, 2014 (not including those who would be laid off), to explain the rationale for the impending layoffs. The memo read, in part, as follows:
“To enable a majority of our team to shift focus to new capabilities , we have executed five new managed services agreements to support testing services and application maintenance. Last week, we began working with both our internal subject matter experts and the suppliers to start transition planning for these agreements. We expect knowledge transfer to start later this month and last through January. Those Cast Members who are involved will be contacted in the next several weeks.”
Responding to the critical New York Times article, Disney represented that when all was said and done, the company had in fact produced a net jobs increase. According to Disney spokesperson Kim Prunty:
“Disney has created almost 30,000 new jobs in the U.S. over the past decade, and the recent changes to our parks’ IT team resulted in a larger organization with 70 additional in-house positions in the U.S. External support firms are responsible for complying with all applicable employment laws for their employees.”
New jobs were promised due to the restructuring, Disney officials said, and employees targeted for termination were pushed to apply for those positions. According to a confidential Disney source, of the approximately 250 laid-off employees, 120 found new jobs within Disney, 40 took early retirement, and 90 were unable to secure new jobs with Disney.
On June 11, 2015, Senator Richard Durbin of Illinois and Senator Jeffrey Sessions of Alabama released a statement regarding a bipartisan letter issued to the attorney general, the Department Homeland Security, and the Department of Labor.
“A number of U.S. employers, including some large, well-known, publicly-traded corporations, have laid off thousands of American workers and replaced them with H-1B visa holders . . . . To add insult to injury, many of the replaced American employees report that they have been forced to train the foreign workers who are taking their jobs. That’s just plain wrong and we’ll continue to press the Administration to help solve this problem.”
In response to request for comment on the communications issues raised by the Disney layoffs and aftermath, New York Times columnist Julia Preston shared the following exclusive analysis:
“I would say Disney’s handling of those lay-offs is a case study in how not to do things. But in the end it’s not about the communications, it’s about the company. Those layoffs showed a company that was not living up to its core vaunted family values and no amount of shouting by their communications folks could change the facts of what happened.”
- Is it ethical for U.S. companies to lay off workers and hire foreign workers under the H-1B program? Should foreign countries restrict the hiring of foreign workers that meet their workforce requirements?
- Discuss the internal and external communications that Disney employed in this situation. The examples here are of the formal written communications. What should Disney have been communicating verbally to their employees and externally?
Boyle, M. (2015). “Ahead of GOP Debate, Two Ex-Disney Workers Displaced by H1B Foreigners Speak Out for First Time,” Breitbart , http://www.breitbart.com/big-governm… for-first-time .
May, C. (2015). “Sens. Dick Durbin (D-IL) and Jeff Sessions (R-AL) say that the Department of Labor has launched an investigation into alleged abuses of the H-1B guest worker program,” Breitbart, http://www.breitbart.com/big-governm...o-h-1b-abus es/ .
Pedicini, S. (2016). “Tech Workers File Lawsuits Against Disney Over H-1B Visas,” Orlando Sentinel, http://www.orlandosentinel.com/busin...125-story.html .
Preston, J. (2015). ”Pink Slips at Disney. But First, Training Foreign Replacements,” The New York Times, https://www.nytimes.com/2015/06/04/us/last-task-after-layoff-at-disne y-train-foreign-replacements.html .
Preston, J. (2016). “EmaEmail Bryan Shannon,” The New York Times.
U.S. Citizenship and Immigration Services. (2016). “Working in the United States,” U.S. Citizenship and Immigration Services, https://www.uscis.gov/eir/visa-guide...b-requirem ents .
Vargas, R. (2015). “EXCLUSIVE: Former Employees Speak Out About Disney's Outsourcing of High-Tech Jobs,” ABC 27, https://www.wtxl.com/news/exclusive-former-employees-speak-out-about-disney-s-outsourcing-of/article_24db73bc-fd32-556b-b793-982a63ba28b4.html .
- What are the four components of communication discussed in this section?
- Why is it important to understand your limitations in communicating to others and in larger groups?
- Why should managers always strive to improve their skills?


66: Education in the (Dis)Information Age (Shaffer)
Kris Shaffer
#education #analysis #argument #technology #advice #logos #disinformation #cognitivebias
“ Cause I'd Rather Pretend I'll Still Be There At The End ” by Bethan Phillips on Flickr; CC BY-NC-ND 2.0
We are all on the front lines in the war against disinformation.
I recently visited a seminar course for history majors at University of Mary Washington. In that course, students are digging into the differences between primary and secondary sources (a letter written by someone vs. a book written about them), learning the different means of evaluating each, and exploring ways to filter through the bias inherent in every source. I was there specifically to help them as they work through how to communicate their findings to a public, non-academic audience on the open web.
As we worked through some of the technical details, we also talked about the importance of what they were doing in that course in terms of the modern information landscape . After all, “fake news” has everyone talking about the reliability and bias of all kinds of information sources. Of all the things we could have talked about, though — Twitter bots , AI-generated video , memes , mainstream vs. partisan news media, Wikipedia, Wikileaks… — we spent most of our time on the hyperlink.
The hyperlink.
The oldest and simplest of internet technologies, the hyperlink and the “new” kind of text it affords — hypertext — is the foundational language of the internet, HyperText Markup Language (HTML) . Hypertext connects all the disparate pieces of the web together. And it’s Sci-Fi name isn’t an accident. It’s hyperdrive for the internet, bending information space so that any user can travel galaxy-scale information distances with a small movement of a finger. The hyperlink still remains one of the most powerful elements of the web. In fact, I’d argue that the hyperlink is our most potent weapon in the fight against disinformation .
Now, I’m not talking about URLs , or “web addresses.” Yes, I can go anywhere on the internet if I know, and type, the right URL into the box at the top of my web browser. But a hyperlink is more than that. My site’s URL is pushpullfork.com, and colloquially many of us would call that the “link” to my site. But this is a hyperlink to my site — a tiny bit of colorful, underlined text that has the power to bend space and move information. That simple idea of text “marked up” with hyperlinks is the revolutionary idea of the internet. And it’s not just “marked up” as in highlighted, underlined, or even digitally annotated — it’s more than just what we’d write in the margins of our physical books. Clicking (or, most likely these days, tapping) on a link can take you to a whole other dimension of the internet. With one pull of the muscles in your finger, you can transform an artifact that looks very much like the artifacts we engaged in our pre-internet world of information poverty — a body of text that we can hold in our hands — into a portal to the world of information abundance .
But what does this have to do with history majors and evaluating information sources?
Think about what a digital historian (or musicologist or journalist or physicist or lawyer) can do with the hyperlink. Let’s take a primary source — an original document produced by people we are studying in the course of events we want to know more about — and see just what it can do.
This is an excerpt from the recently declassified and publicized memo about the FBI investigation into possible collusion between the Trump U.S. presidential campaign and the Russian government. This memo is presented in its original form: a scanned image of a typed and printed paper document. (To be fair, the “original” memo was printed, and before that lived on someone’s computer. But the scanned image is the form it was in when first released to the public as a declassified document.) Here’s the text of that excerpt:
Investigation Update
On October 21, 2016, DOJ and FBI sought and received a FISA probable cause order ( not under Title VII) authorizing electronic surveillance on Carter Page from the FISC. Page is a U.S. citizen who served as a volunteer advisor to the Trump presidential campaign. Consistent with requirements under FISA, the application had to be first certified by the Director or Deputy Director of the FBI. It then required the approval of the Attorney General, Deputy Attorney General (DAG), or the Senate-confirmed Assistant Attorney General for the National Security Division.
The FBI and DOJ obtained one initial FISA warrant targeting Carter Page and three FISA renewals from the FISC. As required by statute (50 U.S.C. §1805(d)(1)), a FISA order on an American citizen must be renewed by the FISC every 90 days and each renewal requires a separate finding of probable cause. Then-Director James Comey signed three FISA applications in question on behalf of the FBI, and Deputy Director Andrew McCabe signed one. Then-DAG Sally Yates, then-Acting DAG Dana Boente, and DAG Rod Rosenstein each signed one or more FISA applications on behalf of DOJ.
By selecting and retyping that excerpt, I’ve already done some significant things. First, I’ve honed in on a particular passage for a particular reason — in this case, one I can use to illustrate my point about hyperlinks. This choice leaves things out, though, and readers who engage it for different purposes may be (mis)led in certain directions because of what was included and what was left out. More digital-specific, I’ve made the text searchable and accessible — the original PDF from which I extracted that image had no embedded text, it was just a scan of a printed document. That means it was inaccessible to people with visual impairments, and was not able to be indexed by search engines. (No doubt there are searchable-text versions floating around by now, but for the sake of our discussion, it is important to note that most primary sources are simple images/scans like this one, which is, after all, the version linked by the New York Times .)
I’ve also added some structure, based on my interpretation. The heading “Investigation Update” was simply underlined in the original, but I know that is an older, typrewriter-based practice that denotes a section heading. So I replaced the underline with an HTML tag (<h3>) that gives it a place in the hierarchy that every web app understands and renders consistently — including screen readers and other text-to-speech apps. (I’ve similarly converted the typewriter-based underlined text to the italics that we’re more used to seeing in books and on the web. Some purists may balk at both of these changes, but based on my expertise in publishing and the web, I’m considering the typewriter and book/web versions equivalent, and “translating” the document from one domain into another.)
But let’s do something a little more dynamic:
Investigation Update
On October 21, 2016, DOJ and FBI sought and received a FISA probable cause order ( not under Title VII) authorizing electronic surveillance on Carter Page from the FISC . Page is a U.S. citizen who served as a volunteer advisor to the Trump presidential campaign. Consistent with requirements under FISA , the application had to be first certified by the Director or Deputy Director of the FBI. It then required the approval of the Attorney General, Deputy Attorney General (DAG), or the Senate-confirmed Assistant Attorney General for the National Security Division.
The FBI and DOJ obtained one initial FISA warrant targeting Carter Page and three FISA renewals from the FISC. As required by statute ( 50 U.S.C. §1805(d)(1) ), a FISA order on an American citizen must be renewed by the FISC every 90 days and each renewal requires a separate finding of probable cause. Then- Director James Comey signed three FISA applications in question on behalf of the FBI, and Deputy Director Andrew McCabe signed one. Then-DAG Sally Yates, then-Acting DAG Dana Boente, and DAG Rod Rosenstein each signed one or more FISA applications on behalf of DOJ.
I’ve added links, obviously. But look more closely at what I’ve added. In the first paragraph, I’ve added links to Wikipedia — a generally reliable source with active checks against overt bias and disinformation, and with its own curated links to other sources. Likewise, the first link in the second paragraph is to the referenced legal code on an informational site hosted by Cornell University. By adding these links, I can provide context that provides balanced, in-depth information to help someone reading this memo for the first time to understand the background and make more informed, nuanced judgments about its content.
But look at the last two links. One is to FoxNews, and the other to FiveThirtyEight. The FoxNews link isn’t really about Andrew McCabe. But it does mention him in the context of a discussion of the top brass at Comey’s FBI … now leaving, and in McCabe’s case “stepping down amid questions about his handling of the Clinton email case,” according to Fox. The FiveThirtyEight piece is about the impact of the release of the Comey letter, and its negative impact on Clinton’s campaign.
While both of these articles present facts, there are clear biases presented as well. Fox’s article attempts to discredit McCabe, where the presence of a link to FiveThirtyEight can betray, or invoke, pro-Clinton and anti-Trump-administration emotions. By linking to either, I can trigger memories and emotions that exert some influence over the reader’s interpretation of what follows in the memo.
And that’s where the history major (or, really, any individual whose mind is tuned to think critically about sources in context) comes in. With experience in evaluating and distinguishing various kinds of sources, the critically minded student can parse these links and filter bias to pull nuanced meaning from these various texts. More importantly in our current information landscape, the student/professor/researcher-as-public-scholar/educated-graduate-as-mindful-citizen can curate the best primary and secondary sources as links, and use the opportunity not simply to prove their credentials and bolster their argument, but to educate the public, bringing more light than heat to whatever issue they are unpacking.
Think about it this way. If I’m the first person to take a primary source, transcribe (or translate) it, and annotate it with hyperlinks, and my public, digital writing gains traction, it will fast become the go-to source at the top of the search results. My hyperlinks and commentary will become the portal to the resources that people engage to gain context, background, and nuance. It’s a tremendous responsibility, but also a tremendous opportunity, to connect my skills as an academic and a humanist to the issues of the day, in an attempt to bring nuance and truth to the public consciousness.
On the flip side, if no one does this, or if they wait too long, the clickbait and conspiracy theories will win out.
Now, some might think that all of this would go without saying. This is the twenty-first century, digital natives, and all that. But there are two huge barriers to this kind of action being the default for educated users of the web.
First, academic work — both for students and faculty — still tends to be centered around traditional, pre-web conventions of writing. The printed book/article/essay, with footnotes and a bibliography, does not speak the language of the web, and footnotes/endnotes on a website do not encourage an audience to engage with more material more deeply. Putting an academic paper on the web is nothing like writing for the web . Until more faculty help their students learn to do the latter (and until faculty promotion and retention policies encourage faculty themselves to be fluent in writing for a public audience on the web), we’ll continue to raise up future generations of graduates (including the next generation of professors) who aren’t ready for their role in the fight against disinformation.
Second, social-media platforms have worked hard to kill the hyperlink . Sure, there are plenty of links to click on, but they aren’t generated by users . Remember the difference between a link and a URL. I can paste a URL into a tweet or a Facebook post and it becomes clickable, but I cannot write in hypertext . I cannot annotate and link my writing with that of others. And including multiple URLs confuses the platforms! (It would be ironic that platforms whose financial well being is determined by clicks would have this problem — if we didn’t know better.) Social media are designed to share text, images, video, and articles, but not to write in hypertext — the language of the web. After all, if I actually click on all those links, I leave the platform… and take my ad-revenue-generating clicks with me. And so I notice more and more that while the students and faculty I work with know what it means to read the language of the web (including clicking on links), they have been conditioned against writing the language of the web (including inserting properly functioning links into their text). It takes a conscious effort to resist this conditioning — conditioning which, in many ways, feels very similar to and is reinforced by traditional, hyperlink-less academic writing.
The internet was created by and for universities and government researchers. It’s not surprising that when researchers first started networking together digitally, they created a language based around a digital form of citation — hypertext. It’s also not surprising that as the internet has become commercialized, the language of open information discovery and sharing has been supplanted by platforms that limit the forms our discourse may take, in order to serve their own profit-driven agendas. As propagandists and perpetrators of (dis)information operations find those social-media limitations amenable to their aims, we need to resist . And we resist not only with better information, and better interpretation, but in recovering the language of the internet — the language of (digital) scholarship.
It’s time we brought back the hyperlink and learned how to really use it. It’s time we used information abundance to our advantage . And it’s time we disentangled our communications from platforms tuned for the spread of disinformation . The health of our democracies just might depend on it.
____________________
Kris Shaffer (@krisshaffer) is a computational musicologist, digital media specialist, author, and coder. He currently works as an Instructional Technology Specialist at the University of Mary Washington and Contributing Editor for Hybrid Pedagogy . He is also the lead author of Open Music Theory . Kris’s work can be found on the open web at pushpullfork.com and on GitHub at github.com/kshaffer .
Education in the (Dis)Information Age by Kris Shaffer was originally published in Hybrid Pedagogy and is licensed under a Creative Commons Attribution-NonCommercial 3.0 International License .


5.2: What Makes a Good Theory?
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- Alison S. Burke, David Carter, Brian Fedorek, Tiffany Morey, Lore Rutz-Burri, & Shanell Sanchez
- Southern Oregon University via OpenOregon
Numerous criminological theories attempt to explain why people commit a crime. What makes one better than another? How do we judge theories against each other? The natural and physical sciences mostly agree on the knowledge of their disciplines. However, criminology is interdisciplinary, and many criminologists may not agree on what causes criminal behavior. For instance, Cooper, Walsh, and Ellis (2010) have looked at the political ideology of criminologists and their preferred or favored theories. Even one’s political leanings can influence a person’s set of beliefs about the causes of crime. [1]
We must apply the scientific criteria to test our theories. Akers and Sellers (2013) have established a set of criteria to judge criminological theories: logical consistency, scope, parsimony, testability, empirical validity, and usefulness. [2] Logical consistency is the basic building block of any theory. It refers to a theory’s ability to “make sense”. Is it logical? Is it internally consistent? A theory’s scope refers to its range, or ranges, of explanations. Does it explain crimes committed by males AND females? Does it explain ALL crimes or just property crime? Does it explain the crime committed by ALL ages or just juveniles? Better theories will have a wider scope or a larger range of explanation.
A parsimonious theory is concise, elegant, and simple. There are not too many constructs or hypotheses. Simply put, parsimony refers to a theory’s “simplicity”. A good scientific theory needs to be testable too. It must be open to possible falsification. “Every genuine test of a theory is an attempt to falsify it or to refute it. Testability is falsifiability; but there are degrees of testability: some theories are more testable, more exposed to refutation than others; they take, as it were, greater risks…One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability” (Popper, 1965, pp. 36-37). [3]
After many tests and different approaches to research, those theories supported by evidence have empirical validity. Thus, according to Gibbs (1990), the verification or repudiation of a given theory through empirical research is the most important principle to judge a theory. [4]
Finally, all theories will suggest how to control, prevent, or reduce crime through policy or program. The premise of a particular theory will guide policy-makers. For example, if a theory suggested that juveniles learn how to commit crime through a network of delinquent peers, policymakers will try to identify juveniles at-risk for joining delinquent subcultures.
-
Cooper, J., Walsh, A., & Ellis, L. (2010). Is criminology ripe for a paradigm shift? Evidence from a survey of American criminologists.
Journal of Criminal Justice Education, 2
, 332-347.
↵
-
Akers, R.L., & Sellers, C.S. (2013).
Criminological theories: Introduction, evaluation, and application
. New York: Oxford.
↵
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Popper, K.R. (1965).
Conjectures and refutations: The growth of scientific knowledge
. New York: Harper Torchbooks.
↵
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Gibbs, J.P. (1990). The notion of theory in sociology.
National Journal of Sociology, 4
, 129-159.
↵


6.3: What Are the Different Citations?
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- Chelsea Milbourne, Anne Regan, Morgan Livingston, & Sadie Johann
- California Polytechnic State University-San Luis Obispo
MLA STYLE
This page is brought to you by the OWL at Purdue ( https://owl.english.purdue.edu/ ). When printing this page, you must include the entire legal notice at the bottom.
Contributors: Kristen Seas, Allen Brizee.
SUMMARY:
Welcome to the OWL Workshop on MLA Style. This workshop will introduce you to the Modern Language Association (MLA) Style for writing and formatting research papers. To get the most out of this workshop, you should begin with the introductory material below, which covers what MLA Style is, why it is used, and who should apply this style to their work. Then you are invited to browse through the OWL's various handouts on different aspects of MLA Formatting and Citations standards, both as sources appear in-text and in the final reference page.
MLA OVERVIEW AND WORKSHOP
Welcome to the OWL Workshop on MLA Style. This workshop will introduce you to the Modern Language Association (MLA) Style for writing and formatting research papers. To get the most out of this workshop, you should begin with the introductory material below, which covers what MLA Style is, why it is used, and who should apply this style to their work. Then you are invited to browse through the OWL's various handouts on different aspects of MLA Formatting and Citations standards, both as sources appear in-text and in the final reference page.
Note: This workshop should answer most of your basic questions about using MLA Style. However, if you are writing a complex document such as a thesis or lengthy manuscript, or if you have detailed questions, you should consult the MLA Handbook (8th Edition), which you can usually find at your local library or in many bookstores.
The MLA also has a website called the MLA Style Center that allows you to order the handbook online. The site also includes resources for students and teachers as well as answers to frequently asked questions on basic details of MLA Style. Purdue's OWL also has a list of Additional Resources covering MLA Style as well.
WHAT IS MLA STYLE?
MLA Style establishes standards of written communication concerning:
- formatting and page layout
- stylistic technicalities (e.g. abbreviations, footnotes, quotations)
- citing sources
- and preparing a manuscript for publication in certain disciplines.
WHY USE MLA?
Using MLA Style properly makes it easier for readers to navigate and comprehend a text by providing familiar cues when referring to sources and borrowed information. Editors and instructors also encourage everyone to use the same format so there is a consistency of style within a given field. Abiding by MLA's standards as a writer will allow you to:
- Provide your readers with cues they can use to follow your ideas more efficiently and to locate information of interest to them
- Allow readers to focus more on your ideas by not distracting them with unfamiliar or complicated formatting
- Establish your credibility or ethos in the field by demonstrating an awareness of your audience and their needs as fellow researchers (particularly concerning the citing of references)
WHO SHOULD USE MLA?
MLA Style is typically reserved for writers and students preparing manuscripts in various humanities disciplines such as:
- English Studies - Language and Literature
- Foreign Language and Literatures
- Literary Criticism
- Comparative Literature
- Cultural Studies
MLA FORMATTING AND NOTATION STYLE
You should start by becoming familiar with the general formatting requirements of MLA Style, as well as the different standards for notation that MLA writers are expected to use. Because MLA is different than other writing styles, such as APA, you should pay attention to every detail of the Style, from general paper layout to abbreviations. The following pages will introduce you to some of these basic requirements of MLA Style to get you started in the right direction.
-
Covers the basic requirements of page layout for a typical
MLA manuscript - Includes general guidelines to apply through the document and specific formatting details for the first page of the paper
- Also provides an image of the sample first page of an essay written in MLA Style
- Explains the necessity for using notes and how to use them effectively in an MLA paper
- Covers different reasons for why you may use a footnote or endnote to supplement the main body of your paper
- Describes how to number and format the notes to be consistent with MLA guidelines
- Describes how to format quotations borrowed from secondary sources
- Addresses both short quotations worked into the writer's own sentences and long quotations that are blocked off as distinct material
- Also explains how to omit or add in words properly to clarify the meaning of a quotation
- Covers MLA standards for abbreviating words commonly used in academic prose
- Describes the different categories of abbreviations: time, locations, academic references, publishers
- Includes guidelines for abbreviating information in citations in a Works Cited page
MLA CITATIONS AND WORKS CITED PAGE
As with any publishing style, the most difficult aspect of MLA Style to master are the requirements for citing secondary sources accurately. The pages included here walk you through the details of incorporating citations into the text of your paper as well as how to compose a work cited page of references at the end of your paper. Read these guidelines carefully. It is important that you refer to your sources according to MLA Style so your readers can quickly follow the citations to the reference page and then, from there, locate any sources that might be of interest to them. They will expect this information to be presented in a particular style, and any deviations from that style could result in confusing your readers about where you obtained your information.
How to Document Sources in MLA Style: An Overview
- Covers the process for developing Works Cited lists and in-text citations advocated in MLA (8th ed.)
- Explains "containers," a concept new to the eighth edition, including how to use them to develop citations
- Addresses the formatting requirements of using the MLA Style for citing secondary sources within the text of your essay
- Offers a few basic rules for using parenthetical citations, including when not to use such citations
- Includes examples of in-text citations
- Explains the author-page formatting of the parenthetical citation and how that applies to different types of sources
- Provides examples of in-text citations based on the kind of source being cited, such as a literary work, an anonymous work, and work with multiple authors
- Also describes how to cite a source indirectly referenced in another source
Works Cited Page: Basic Format
- Guides you through the general rules that apply to any works cited page using MLA Style, from where the page appears and how to list the works
- Walks you through how to construct a reference entry for different text starting with a focus on author
- Serves as a primer on formatting that will be followed in all of the following handouts on creating MLA works cited entries
- Includes example Works Cited Page
- Builds from the basic format page with a focus on how to create citations for types of commonly referenced book sources
- Includes guidelines and examples for a variety of books depending on the number of authors, whether the work is a piece is a larger work, or if the book itself is part of a multivolume collection
Works Cited Page: Other Common Sources
- Provides guidelines on how to reference other sources you may encounter during research that are considered books or non-periodical works
- Includes works that you might likely use but have different publication information, such as a government document, pamphlet, and dissertations
- Covers the guidelines for developing a citation entry for works found in periodicals, typically articles in circulating publications that have different dates and volume/issue numbers
- Lists types of entries depending on the kind of journal (e.g. one paginated by volume), if the source is a magazine v. a newspaper, or the kind of article the source is (e.g. a letter to the editor)
Works Cited Page: Electronic Sources
- Walks through the basic requirements and unique qualifications for constructing references for different types of electronic sources
- Covers more standard sources from online periodicals and scholarly databases, to less conventional sources like emails and video recordings found online
- Includes OWL suggestions on how to cite weblog entries and comments posted to blogs (NOTE: consult your instructor to find out if these are acceptable research sources to use)
Works Cited Page: Other Non-Print Sources
- Applies the basic MLA citation rules to non-print sources you may use in your research, such as interviews and images
- Provides directions and examples of how to cite video and sound recordings, as well as three-dimensional works like sculptures
MLA Eighth Edition: What's New and Different
- Explains major changes from MLA seventh edition (2009) to eighth edition (2016)
Please Note: If you know exactly what you're looking for concerning MLA, you can use the OWL Navigation to the left by looking under "Research and Citation" and clicking on "MLA Formatting and Style Guide." You may also use the search box at the top of the navigation bar to find resources.
APA STYLE
Contributors: Kristen Seas, Allen Brizee.
SUMMARY:
This workshop provides an overview of the APA (American Psychological Association) style and where to find help with different APA resources. It provides an annotated list of links to all of our APA materials and an APA overview. It is an excellent place to start to learn about APA format.
APA STYLE WORKSHOP
Welcome to the OWL Workshop on APA Style! This workshop will introduce you to important aspects of using the American Psychological Association (APA) Style to write and format research papers. You should begin with the introductory material, which covers what APA Style is, why it is used, and who should apply it to their work. Then you are invited to work through the OWL's handouts on APA Formatting and Writing Style , as well as APA Citations and Reference Lists .
NOTE: This workshop should answer most of your basic questions about using APA Style. However, if you are writing a complex document such as a thesis or lengthy manuscript, or if you have detailed questions, you should consult The Publication Manual of the American Psychological Association (6th edition), which you can usually find at your local library or in many bookstores.
The APA also has a website that allows you to order the book online and read some of their frequently asked questions about APA style. Purdue's OWL also has a list of Additional Resources covering APA style that you can consult.
WHAT IS APA STYLE?
APA Style establishes standards of written communication concerning:
- the organization of content
- writing style
- citing references
- and how to prepare a manuscript for publication in certain disciplines.
WHY USE APA?
Aside from simplifying the work of editors by having everyone use the same format for a given publication, using APA Style makes it easier for readers to understand a text by providing a familiar structure they can follow. Abiding by APA's standards as a writer will allow you to:
- Provide readers with cues they can use to follow your ideas more efficiently and to locate information of interest to them
- Allow readers to focus more on your ideas by not distracting them with unfamiliar formatting
- Establish your credibility or ethos in the field by demonstrating an awareness of your audience and their needs as fellow researchers
WHO SHOULD USE APA?
APA Style describes rules for the preparation of manuscripts for writers and students in:
- Social Sciences, such as Psychology, Linguistics, Sociology, Economics, and Criminology
- Business
- Nursing
Before you adopt this style for your paper, you should check to see what citation style your discipline uses in its journals and for student research. If APA Style is appropriate for your writing project, then use this workshop to learn more about APA and how to follow its rules correctly in your own work.
APA FORMATTING AND WRITING STYLE
You should start by becoming familiar with the general formatting requirements of APA Style, as well as the different standards for writing that are expected among APA writers. Because APA is different than other writing styles, you should pay attention to everything from general paper layout to word choice. The following pages will introduce you to some of these basic requirements of APA Style to get you started in the right direction.
- Covers the basic page layout for a typical APA manuscript, including everything from margin widths to the use of headings and visuals
- Includes a general list of the basic components of an APA paper: title page, abstract, and reference page
- Describes the two most common types of APA papers: the literature review and the experimental report
- Outlines what sections must be included in each type of paper, from introductions to a methods section
- Describes three basic areas of stylistic concerns when writing in an APA field: point of view, clarity/conciseness, and word choice
- Explains how poetic language and devices should be avoided in APA reviews and reports
- Suggestions and examples are given for each stylistic issue
APA Stylistics: Things to Avoid
- Identifies the risk of bias in language concerning gender, race, disability, and sexuality when writing up research in APA fields
- Provides links to APA's official guidelines on avoiding bias
- Offers suggestions on finding alternatives to gendered pronouns and using different descriptors when identifying people in your research
APA CITATIONS AND REFERENCE LIST
Perhaps the trickiest part of mastering APA Style is understanding the requirements for citing and listing secondary sources accurately. The following pages walk you through the details of writing citations and developing a reference page at the end of your paper. Read these guidelines carefully! It is important that you refer to your sources according to APA Style so your readers can quickly follow the citations to the reference page and then, from there, locate any sources that might be of interest to them. They will expect this information to be presented in a particular style, and any deviations from that style could result in confusing your readers about where you obtained your information.
- Addresses the basic formatting requirements of using the APA Style for citing secondary sources within the text of your essay
- Provides guidance on how to incorporate different kinds of references to borrowed material, from short quotes to summaries or paraphrases
In-Text Citations: Author/Authors
- Focuses on various details about referring to the authors of your sources within your essay, which can be difficult to do efficiently if the source has more than one author or has an unclear author (e.g. an organization)
- Describes how to cite indirect quotes, electronic sources, and/or sources without page numbers
- Recommends using footnotes or endnotes to avoid long explanations in the text
- Covers two basic kinds of notes: bibliographic and digressive
- Guides you through the general rules that apply to any reference list developed using APA Style
- Covers everything from where the reference list appears to the capitalization of words in the titles of sources
- Serves as a primer on formatting that will be followed in all of the following handouts on creating APA reference entries
Reference List: Author/Authors
- Walks you through how to construct a reference entry for different text starting with a focus on author
- Notes how the references are different depending on the number of authors or if there are multiple works by the same author
Reference List: Articles in Periodicals
- Builds from the previous handout by looking specifically at how to refer accurately to a periodical source
- Lists types of entries depending on the kind of journal (e.g. one paginated by volume), if the source is a magazine v. a newspaper, or the kind of article the source is (e.g. a letter to the editor)
- Builds from the author handout by describing how to properly refer to book-length sources
- Addresses both the basic format as well as requirements for those unique book sources that require you to note specific details, such as whether it is a translation or part of a multivolume work
Reference List: Other Print Sources
- Offers a short list of other less common print sources you might be citing in your manuscript and how to construct references for them
- Covers examples such as citing a source that is cited in another, or citing a government document
Reference List: Electronic Sources
- Walks through the requirements and unique qualifications (see the Notes throughout the page) for constructing references for electronic sources
- Covers sources from online periodicals and scholarly databases, to emails.
Reference List: Other Non-Print Sources
- Focuses primarily on how to reference video and audio texts that are used as sources, from movie clips to sound recordings
- Notes that personal communication (e.g. an interview or conversation) is not to be included in the reference list.
Owl at Purdue -- Copyright ©1995-2017 by The Writing Lab & The OWL at Purdue and Purdue University .
IEEE STYLE
The Institute of Electrical and Electronics Engineers (IEEE) style is a widely accepted format for writing research papers,[citation needed] commonly used in technical fields, particularly in computer science. IEEE style is based on the Chicago Style.[1] In the IEEE style, citations are numbered, but citation numbers are included in the text in square brackets rather than as superscripts. All bibliographical information is exclusively included in the list of references at the end of the document, next to the respective citation number.
LICENSES AND ATTRIBUTIONS
- “MLA and APA Style Guides” by Owl at Purdue -- Copyright ©1995-2017 by The Writing Lab & The OWL at Purdue and Purdue University .
- “ IEEE Style ” by Wikipedia licensed under ( CC BY-SA 4.0 )


15.5: The Big Bang in Eras
To look at the development of the Universe through the Big Bang, astronomers have divided the development into steps or
eras
. These eras are our best scientific match to the data we currently have; they seem scientifically sensible. New data is being used to revise and heighten our understanding of these eras.
The generally accepted Big Bang Eras include:
- Planck
- Grand Unification Theory (GUT)
- Electroweak
- Particle
- Nucleosynthesis
- Nuclei
- Atoms
- Galaxies
A summary of the Big Bang events occurred in this order:
- Big Bang beginning – a bright and hot event →
- Planck Era ; initial energy →
- Elementary Particles – photons create particles and antiparticles →
- Inflation of the Universe →
- Four Forces become distinct (strong, weak, electromagnetic, and gravity) →
- Protons, Neutrons, Electrons, and Neutrinos formed →
- Hydrogen ions fusion into helium ions →
- Stable, Neutral Atoms formed →
- Protoclouds formed →
- Stars, stellar systems, galaxies formed →
- Life, Humans; today


12.9.4: Careers
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Career Paths in Information Systems
These job descriptions do not represent all possible jobs within an information-systems organization. Larger organizations will have more specialized roles; smaller organizations may combine some of these roles. Many of these roles may exist outside of a traditional information-systems organization, as we will discuss below.
Working with information systems can be a rewarding career choice. Whether you want to be involved in very technical jobs (programmer, database administrator), or you want to be involved in working with people (systems analyst, trainer), there are many different career paths available.
Many times, those in technical jobs who want career advancement find themselves in a dilemma: do they want to continue doing technical work, where sometimes their advancement options are limited, or do they want to become a manager of other employees and put themselves on a management career track? In many cases, those proficient in technical skills are not gifted with managerial skills. Some organizations, especially those that highly value their technically skilled employees, will create a technical track that exists in parallel to the management track so that they can retain employees who are contributing to the organization with their technical skills.
Sidebar: Are Certifications Worth Pursuing?
As technology is becoming more and more important to businesses, hiring employees with technical skills is becoming critical. But how can an organization ensure that the person they are hiring has the necessary skills? These days, many organizations are including technical certifications as a prerequisite for getting hired.
Certifications are designations given by a certifying body that someone has a specific level of knowledge in a specific technology. This certifying body is often the vendor of the product itself, though independent certifying organizations, such as CompTIA , also exist. Many of these organizations offer certification tracks, allowing a beginning certificate as a prerequisite to getting more advanced certificates. To get a certificate, you generally attend one or more training classes and then take one or more certification exams. Passing the exams with a certain score will qualify you for a certificate. In most cases, these classes and certificates are not free and, in fact, can run into the thousands of dollars. Some examples of the certifications in highest demand include Microsoft (software certifications), Cisco (networking), and SANS (security).
For many working in IT (or thinking about an IT career), determining whether to pursue one or more of these certifications is an important question. For many jobs, such as those involving networking or security, a certificate will be required by the employer as a way to determine which potential employees have a basic level of skill. For those who are already in an IT career, a more advanced certificate may lead to a promotion. There are other cases, however, when experience with a certain technology will negate the need for certification. For those wondering about the importance of certification, the best solution is to talk to potential employers and those already working in the field to determine the best choice.


2.2: Natural Numbers. Induction
The element 1 was introduced in Axiom 4(b). Since addition is also assumed known, we can use it to define, step by step, the elements
\[2=1+1,3=2+1,4=3+1, \text{ etc.}\]
If this process is continued indefinitely, we obtain what is called the set \(N\) of all natural elements in the given field \(F .\) In particular, the natural elements of \(E^{1}\) are called natural numbers . Note that
\[(\forall n \in N) \quad n+1 \in N\]
*A more precise approach to natural elements is as follows. \(A\) subset \(S\) of a field \(F\) is said to be inductive iff
\[\begin{align} (i)& \hskip 4pt 1 \in S \text{ and } \\ (ii)& \hskip 4pt (\forall x \in S) \hskip 4pt x+1 \in S \end{align}\]
Such subsets certainly exist; e.g., the entire field \(F\) is inductive since
\[1 \in F \text{ and } (\forall x \in F) \hskip 4pt x+1 \in F.\]
Define \(N\) as the intersection of all inductive sets in \(F\).
The set \(N\) so defined is inductive itself. In fact, it is the "smallest" inductive subset of \(F\) (i . e ., contained in any other such subset).
- Proof
-
We have to show that
\[\begin{align} (i)& \hskip 4pt 1 \in N, \text{ and } \\ (ii)& \hskip 4pt (\forall x \in N) \hskip 4pt x+1 \in N. \end{align}\]
Now, by definition, the unity 1 is in each inductive set; hence it also belongs to the intersection of such sets, i.e., to \(N .\) Thus \(1 \in N,\) as claimed.
Next, take any \(x \in N .\) Then, by our definition of \(N, x\) is in each inductive set \(S ;\) thus, by property \((i i)\) of such sets, also \(x+1\) is in each such \(S\) ; hence \(x+1\) is in the intersection of all inductive sets, i.e.,
\[x+1 \in N\]
and so \(N\) is inductive, indeed.
Finally, by definition, \(N\) is the common part of all such sets and hence contained in each. \(\square\)
For applications, Theorem 1 is usually expressed as follows.
(first induction law). A proposition \(P(n)\) involving a natural \(n\) holds for all \(n \in N\) in a field \(F\) if
\[\begin{align} (i)& \text{ it holds for } n=1,\text{ i.e., } P(1) \text{ is true; and } \\ (ii)& \text{ whenever } P(n) \text{ holds for } n=m, \text{ it holds for } n=m+1, \text{ i.e., } \end{align} \]
\[P(m) \Longrightarrow P(m+1).\]
- Proof
-
Let \(S\) be the set of all those \(n \in N\) for which \(P(n)\) is true,
\[S=\{n \in N | P(n)\}\]
We have to show that actually each \(n \in N\) is in \(S,\) i.e., \(N \subseteq S\)
First, we show that \(S\) is inductive .
Indeed, by assumption \((\mathrm{i}), P(1)\) is true; so 1\(\in S\).
Next, let \(x \in S .\) This means that \(P(x)\) is true. By assumption (ii), however, this implies \(P(x+1),\) i.e., \(x+1 \in S .\) Thus
\[ 1 \in S \text{ and } (\forall x \in S) \hskip 4pt x+1 \in S\]
\(S\) is inductive.
Then, by Theorem 1 (second clause), \(N \subseteq S,\) and all is proved. \(\square\)
This theorem is used to prove various properties of \(N\) " by induction ."
(a) If \(m, n \in N,\) then also \(m+n \in N\) and \(m n \in N\).
To prove the first property, fix any \(m \in N .\) Let \(P(n)\) mean
\[m+n \in N \quad(n \in N)\]
Then
(i) \(P(1)\) is true, for as \(m \in N,\) the definition of \(N\) yields \(m+1 \in N\), i.e., \(P(1)\).
(ii) \(P(k) \Rightarrow P(k+1)\) for \(k \in N .\) Indeed,
\[\begin{align} P(k) \Rightarrow& m+k \in N \Rightarrow(m+k)+1 \in N\ \\ \Rightarrow& m+(k+1) \in N \Rightarrow P(k+1) \end{align}\]
Thus, by Theorem \(1^{\prime}, P(n)\) holds for all \(n ;\) i.e.,
\((\forall n \in N) \quad m+n \in N\)
for any \(m \in N\).
To prove the same for \(m n,\) we let \(P(n)\) mean
\(m n \in N \quad(n \in N)\)
and proceed similarly.
(b) If \(n \in N,\) then \(n-1=0\) or \(n-1 \in N\).
For an inductive proof, let \(P(n)\) mean
\[n-1=0 \text{ or } n-1 \in N \quad(n \in N)\]
Then proceed as in (a).
(c) In an ordered field, all naturals are \(\geq 1\).
Indeed, let \(P(n)\) mean that
\[n \geq 1 \quad(n \in N).\]
Then
(i) \(P(1)\)
holds
since \(1=1\)
(ii) \(P(m) \Rightarrow P(m+1)\) for \(m \in N,\) since
\[P(m) \Rightarrow m \geq 1 \Rightarrow(m+1)>1 \Rightarrow P(m+1)\]
Thus Theorem \(1^{\prime}\) yields the result.
(d)
In an ordered field
, \(m, n \in N\) and \(m>n\) implies \(m-n \in N\)
For an inductive proof, fix any \(m \in N\) and let \(P(n)\) mean
\[m-n \leq 0 \text{ or } m-n \in N \quad(n \in N).\]
Use (b).
(e) In an ordered field, \(m, n \in N\) and \(m<n+1\) implies \(m \leq n\)
For, by \((\mathrm{d}), m>n\) would imply \(m-n \in N,\) hence \(m-n \geq 1,\) or \(m \geq n+1,\) contrary to \(m<n+1\).
Our next theorem states the so-called well-ordering property of \(N\).
In an ordered field, each nonvoid set \(A \subseteq N\) has a least member (i.e., one that exceeds no other element of \(A )\).
- Proof
-
The following is just an outline of a proof:
Given \(\emptyset \neq A \subseteq N,\) let \(P(n)\) be the proposition "Any subset of \(A\) containing elements \(\leq n\) has a least member" \((n \in N) .\) Use Theorem \(1^{\prime}\) and Example (e) . \(\square\)
This theorem yields a new form of the induction law.
A proposition \(P(n)\) holds for all \(n \in N\)
(i') \(P(1)\) holds and
(ii') whenever \(P(n)\) holds for all naturals less than some \(m \in N,\) then \(P(n)\)
also holds for \(n=m\).
- Proof
-
Assume \(\left(\mathrm{i}^{\prime}\right)\) and \(\left(\mathrm{ii}^{\prime}\right) .\) Seeking a contradiction, suppose there are some \(n \in N(\) call them "bad") for which \(P(n)\) fails. Then these "bad" naturals form a nonvoid subset of \(N,\) call it \(A\).
By Theorem \(2, A\) has a least member \(m .\) Thus \(m\) is the least natural for which \(P(n)\) fails. It follows that all \(n\) less than \(m\) do satisfy \(P(n) .\) But then, by our assumption (ii'), \(P(n)\) also holds for \(n=m,\) which is impossible for, by construction, \(m\) is "bad" (it is in \(A ) .\) This contradiction shows that there are no "bad" naturals. Thus all is proved. \(\square\)
Note 1: All the preceding arguments hold also if, in our definition of \(N\) and all formulations, the unity 1 is replaced by 0 or by some \(k( \pm k \in N)\). Then, however, the conclusions must be changed to say that \(P(n)\) holds for all integers \(n \geq k\) (instead of "n \geq 1 "). We then say that "induction starts with \(k .\)"
An analogous induction law also applies to definitions of concepts \(C(n)\).
\(A\) notion \(C(n)\) involving a natural \(n\) is regarded as defined for each \(n \in N\) \(\left(i n E^{1}\right)\) if
(i) \(i t\) is defined for \(n=1\) and
(ii) some rule is given that expresses \(C(n+1)\) in terms of \(C(1), \ldots, C(n)\).
(Note 1 applies here, too.)
\(C(n)\) itself need not be a number ; it may be of quite general nature.
We shall adopt this principle as a kind of logical axiom, without proof (though it can be proved in a similar manner as Theorems \(1^{\prime}\) and \(2^{\prime} ) .\) The underlying intuitive idea is a "step-by-step" process - first, we define \(C(1) ;\) then, as \(C(1)\) is known, we may use it to define \(C(2) ;\) next, once both are known, we may use them to define \(C(3) ;\) and so on, ad infinitum. Definitions based on that principle are called inductive or recursive . The following examples are important.
(f) For any element \(x\) of a field, we define its \(n^{th}\) power \(x^{n}\) and its \(n\)- multiple \(n x\) by
(i) \(x^{1}=1 x=x\)
(ii) \(x^{n+1}=x^{n} x\) (respectively, \((n+1) x=n x+x )\).
We may think of it as a step-by-step definition:
\[x^{1}=x, x^{2}=x^{1} x, x^{3}=x^{2} x, \text{ etc.}\]
(g) For each natural number \(n,\) we define its factorial \(n !\) by
\[1 !=1,(n+1) !=n !(n+1);\]
e.g. \(, 2 !=1 !(2)=2,3 !=2 !(3)=6,\) etc. We also define \(0 !=1\).
(h) The sum and product of n field elements \(x_{1}, x_{2}, \dots, x_{n},\) denoted by
\[\sum_{k=1}^{n} x_{k} \text{ and } \prod_{k=1}^{n} x_{k}\]
or
\[x_{1}+x_{2}+\cdots+x_{n} \text{ and } x_{1} x_{2} \cdots x_{n}, \text{ respectively}\]
are defined recursively.
Sums are defined by
\[ \begin{align} (i)& \hskip 4pt \sum_{k=1}^{1} x_{k}=x_{1} \\ (ii)& \hskip 4pt \sum_{k=1}^{n+1} x_{k}=\left(\sum_{k=1}^{n} x_{k}\right)+x_{n+1}, n=1,2, \ldots \end{align}\]
Thus
\[x_{1}+x_{2}+x_{3}=\left(x_{1}+x_{2}\right)+x_{3}\]
\[x_{1}+x_{2}+x_{3}+x_{4}=\left(x_{1}+x_{2}+x_{3}\right)+x_{4}, \text{ etc.}\]
Products are defined by
\[ \begin{align}(i)& \hskip 4pt \prod_{k=1}^{1} x_{k}=x_{1} \\ (ii)& \hskip 4pt \prod_{k=1}^{n+1} x_{k}=\left(\prod_{k=1}^{n} x_{k}\right) \cdot x_{n+1} \end{align}\]
(i) Given any objects \(x_{1}, x_{2}, \dots, x_{n}, \ldots,\) the ordered n-tuple
\[\left(x_{1}, x_{2}, \ldots, x_{n}\right)\]
is defined inductively by
(i) \(\left(x_{1}\right)=x_{1}\) (i.e., the ordered "one-tuple" \(\left(x_{1}\right)\) is \(x_{1}\) itself \()\) and
(ii) \(\left(x_{1}, x_{2}, \ldots, x_{n+1}\right)=\left(\left(x_{1}, \ldots, x_{n}\right), x_{n+1}\right),\) i.e., the ordered \((n+1)-\) tuple is a pair \(\left(y, x_{n+1}\right)\) in which the first term \(y\) is itself an ordered \(n\) -tuple, \(\left(x_{1}, \ldots, x_{n}\right) ;\) for example,
\[\left(x_{1}, x_{2}, x_{3}\right)=\left(\left(x_{1}, x_{2}\right), x_{3}\right), \text{ etc.}\]


8.4: Social and Community Context
By the end of this section, you should be able to:
- Describe the impact of civic participation on individual health.
- Define discrimination and discuss its impact on the social determinants of health.
- Explain how incarceration is linked to the other social determinants of health.
- Discuss the importance of social capital and cohesion in relation to health outcomes.
The social and community context determinant of health includes civic participation, discrimination, incarceration , and social cohesion. Because relationships with family, friends, colleagues, and neighbors greatly impact health and well-being, Healthy People 2030 focuses on increasing social and community support (ODPHP, 2020f). Positive relationships help buffer the negative effects of unsafe neighborhoods, discrimination, and poverty and, by extension, improve overall health and well-being (ODPHP, 2020f).
Civic Participation
Civic participation refers to a range of activities that benefit the community and provide health benefits for participants (APA, 2023). Civic participation helps build social capital , the value gained from having positive interactions and connections between people that enables the community to function effectively and collaboratively in problem-solving efforts. It is these relationships and networks that support the neighborhood and community. By building social capital via civic engagement, members of civic groups are more likely to be physically active and to engage in meaningful activities, providing a sense of purpose (ODPHP, 2020g). Examples include volunteering at community parks, nature reserves, senior centers, community centers, and adult day centers. It can also include civic engagement in the form of environmentalism, education, recycling efforts, composting, farming, and community gardening. Overall, volunteers experience increased psychological well-being and emotional health (ODPHP, 2020g), and adult volunteers aged 60 and above have a lower risk of cognitive impairment (Infurna et al., 2016). Community gardening is associated with increased neighborhood pride, motivation to be involved, and access to healthy foods (Figure 8.5) (ODPHP, 2020g). Group membership has also been found to increase social capital and benefit members by increasing opportunities for social gatherings. Groups such as the Lions Club, Girl Scouts, and Rotary International clubs can be formal, and there can be informal groups, such as book clubs and walking groups (ODPHP, 2020g). Ultimately, individuals and families who are active in their community and have connections with other individuals in their community are happier and healthier.
Discrimination
As discussed in Structural Racism and Systemic Inequities, discrimination refers to unfair treatment of individuals and groups based on certain characteristics such as race , ethnicity , gender , age , religion , sexual orientation , and ability (ODPHP, 2020h). It assigns value based on the social interpretation of how one looks or acts, and it manifests in social actions aimed at protecting more privileged groups at the expense of less privileged ones (ODPHP, 2020h). Discrimination is prevalent in the United States, where 63 percent of adults report experiencing discrimination every day, impacting a variety of population groups, such as older adults, certain ethnic and racial groups, individuals identifying as lesbian, gay, bisexual, transgender, and queer/questioning, (LGBTQ), and individuals experiencing disabilities (ODPHP, 2020h). Discrimination is a public health threat. It can precede stress-related emotional, physical, and behavioral changes, resulting in adverse health outcomes across the age spectrum (APA, 2022). These adverse health outcomes include tachycardia, anxiety, hypertension, and gastrointestinal ulcers that lead to negative long-term health outcomes over time. Caring for Vulnerable Populations and Communities discusses the effects of discrimination on health outcomes in more detail.
Discrimination occurs at both the individual and structural levels. Structural discrimination refers to institutional policies, systems, laws, and practices that limit individuals’ and populations’ opportunities, resources, and power based on race, ethnicity, gender, ability, SES, and religion. These deeply rooted practices and beliefs propagate pervasive unjust treatment and oppression of individuals (Braveman et al., 2022).
Discrimination based on race has been linked to significant disparities in health outcomes, attributed to the cumulative effects of racism on the body. Structural racism in health care often results in Black clients receiving poorer-quality care. The 2019 National Healthcare Disparities Report found that White clients receive a better quality of care than almost 41 percent of Black clients (Taylor et al., 2019). In 2018, non-Hispanic Black infants in the United States had 2.4 times the infant mortality rate of White infants (USDHHS Office of Minority Health, 2021). This disparity is rooted in racism; structural racism has resulted in Black women receiving poorer-quality care. On an individual level, the stress from enduring discrimination and racism is cumulative and triggers biological processes that places these women at higher risk for pregnancy-related complications such as preeclampsia, eclampsia, embolisms, and mental health related issues (Taylor et al., 2019). Structural Racism and Systemic Inequities discusses race-based structural discrimination in more detail.
This animation defines intersectionality and explores the reasons why common approaches of addressing discrimination fall short in addressing all the negative factors that may hinder an individual’s well-being.
Watch the video, and then respond to the following questions.
- How would you explain intersectionality?
- How can the nurse apply the concept of intersectionality in community health nursing?
- Can you think of any client encounters from clinical or work experiences where you witnessed the intersection of multiple forms of discrimination at one time? How did this make you feel?
Incarceration
Incarceration refers to confinement in a prison or a jail. Incarceration affects the health of those incarcerated and their families and communities. BIPOC communities and individuals with lower levels of education are disproportionately affected by higher incarceration rates due to the federal policies of the 1960s and 1970s resulting in increased police surveillance and mass incarceration . As of 2018, Black Americans were incarcerated at more than five times the rate of White Americans (Gramlich, 2020). That year, Black Americans represented approximately 12 percent of the U.S. adult population, yet they represented 33 percent of the incarcerated population, while White Americans represented 63 percent of the U.S. adult population and comprised 30 percent of the incarcerated population (Gramlich, 2020). During this same time period, Hispanic Americans represented 16 percent of the U.S. adult population but accounted for 23 percent of the incarcerated population (Gramlich, 2020). Data indicates that White men without a high school diploma or General Education Development (GED) equivalent have a significantly higher risk of being incarcerated (1 in 8) when compared to their more educated peers (1 in 57) (ODPHP, 2020i). Communities with higher rates of poverty and unemployment are disproportionately burdened by higher incarceration and recidivism (being arrested or incarcerated again) rates (ODPHP, 2020i). Structural Racism and Systemic Inequities and Caring Across Practice Settings discuss issues related to incarceration in more detail.
Individuals with a history of incarceration have been found to have worse physical and mental health compared to the general population. Women in this demographic are more likely to have experienced ACEs than women not in the criminal justice system, illustrating how early childhood experiences place certain individuals at higher risk for adverse life outcomes (ODPHP, 2020i). Individuals who have experienced incarceration have higher rates of mental health disorders, hypertension, asthma, cancer, arthritis, tuberculosis, hepatitis C, and HIV (ODPHP, 2020i). This heavy disease burden has implications for when these individuals reenter the community. Already at a financial disadvantage, they may have trouble finding employment and a place to live given their criminal record and lack the resources to seek the medical care needed to manage their conditions. This reinforces the cycle of poverty and poor health outcomes. The United States releases millions of individuals from jail and prison each year, yet recidivism is fairly common, as more than 50 percent of individuals are incarcerated again within 3 years of their initial release. This may be due to the obstacles these individuals face when reentering society (ODPHP, 2020i).
Incarceration often negatively impacts the families of those individuals who are incarcerated. Almost half of incarcerated individuals have minor children, about 19 percent of whom are age 4 or younger (Wang, 2022). Having a parent incarcerated is considered an ACE because it places these children at higher risk for cognitive and health-related challenges throughout their lives and because they are more likely to live in poverty and be homeless (ODPHP, 2022i). These children have higher rates of developmental delays, learning difficulties, speech and language issues, attention disorders, and aggressive behaviors, and they are up to five times more likely to be involved with the criminal justice system than children without incarcerated parents (ODPHP, 2020i). Illustrating the generational effects of parental incarceration as an ACE, many incarcerated parents also grew up in challenging situations:
- 17 percent spent time in foster care.
- 43 percent are from families that received public assistance.
- 19 percent lived in public housing before the age of 18.
- 11 percent were homeless at one point before the age of 18.
- 32 percent had or currently have an incarcerated parent (Wang, 2022).
Community and public health nurses have a role in identifying children who are at risk due to parental incarceration. After identification, nurses can begin a targeted approach to secure access to resources and educational programs aimed at supporting these children and their caregivers. This involves an interprofessional team of school nurses, guidance counselors, and therapists and early childhood educational programs for those that qualify. Community and public health nurses can collaborate with the justice system to advocate for programs such as drug treatment courts to help keep individuals out of prison while treating their addiction (ODPHP, 2020i). Correctional nurses can provide and advocate for comprehensive health services during incarceration to address the individual’s holistic needs (ODPHP, 2020i; see Caring Across Practice Settings) . Community nurses can help individuals who reenter the community access health care, employment resources, food, and housing.
Social Cohesion
Social cohesion refers to the strengths of relationships within a community (ODPHP, 2020j). An indicator of social cohesion is the amount of social capital within a community. Places of worship, community centers, libraries, and families are common sources of social capital. Collective efficacy is another aspect of social cohesion and is based on trust. It refers to a community’s ability to create change and influence behavior through social norms (ODPHP, 2020j). This is associated with improved self-rated health, lower rates of neighborhood violence, and improved access to medical care, healthy food, and places to exercise (Matsaganis & Wilkin, 2015).
Research has demonstrated that high levels of social support positively influence health outcomes such as healthier eating habits, exercise, and even dealing with stress (ODPHP, 2020j). For example, social support contributes to lower atherosclerosis levels (Shah et al., 2021) and is a protective barrier to the harmful consequences of discrimination for many first-generation immigrants (Szaflarski & Bauldry, 2019). Many studies have linked social isolation to detrimental health effects and increased overall mortality , especially in older adults (ODPHP, 2020j). The CDC considers loneliness and social isolation in older adults a significant public health threat, with almost one quarter of adults ages 65 and older considered socially isolated (CDC, 2019). Social isolation also disproportionately affects vulnerable populations, including immigrants and lesbian, gay, bisexual, and transgender (LGBT) populations (CDC, 2019). Social isolation and loneliness are associated with the following health outcomes (CDC, 2019):
- 50 percent increased risk of dementia
- 29 percent increased risk of heart disease
- 32 percent increased risk of stroke
- Higher rates of depression, anxiety, and suicide
Social networks are foundational to a healthy and thriving community. They create social cohesion, can spread positive health behaviors, and give a sense of community to individuals and families (ODPHP, 2020j). Community and public health nurses are well positioned to foster the development of social networks, especially in vulnerable populations. Through senior centers, councils on aging, ethnic centers, local Boys and Girls Clubs, local Y clubs (formerly known as the YMCA), libraries, local government offices, and assisted living facilities, community health nurses can nurture the development of community groups and events (Figure 8.6). By helping to develop programming to refer at-risk individuals and families to existing programs, nurses can make an impact.
The University of Wisconsin Population Health Institute, with the Robert Wood Johnson Foundation’s support, has conceptualized a population health model illustrating a broad vision for health, demonstrating how policies and programs shape a community’s health and outcomes, both quantity and quality of life. This video highlights this model, showing all the factors that impact health (the SDOH) and demonstrating that upstream interventions can be implemented at the population health level to ensure that each individual and community thrives.
Watch the video, and then respond to the following questions.
- What are your impressions of this model?
- Do you feel the model is an accurate representation of the intersection of health and social, economic, and environmental factors? Why or why not?
- How might one use this model in population health nursing?


3.2: The Plasma Membrane
The thin plasma membrane surrounds the cell, separating its contents from the surroundings and controlling what enters and leaves the cell. The plasma membrane is composed of two main molecules,phospholipids(fats) and proteins. The phospholipids are arranged in a double layer with the large protein molecules dotted about in the membrane (see diagram 3.4). Some of the protein molecules form tiny channels in the membrane while others help transport substances from one side of the membrane to the other.
Diagram 3.4 : The structure of the plasma membrane
How substances move across the Plasma Membrane
Substances need to pass through the membrane to enter or leave the cell and they do so in a number of ways. Some of these processes require no energy i.e. they are passive, while others require energy i.e. they are active .
Passive processes include: a) diffusion and b) osmosis, while active processes include: c) active transport, d) phagocytosis, e) pinocytosis and f) exocytosis. These will be described below.
Diffusion
Although you may not know it, you are already familiar with the process of diffusion. It is diffusion that causes a smell (expensive perfume or smelly socks) in one part of the room to gradually move through the room so it can be smelt on the other side. Diffusion occurs in the air and in liquids.
Diagram 3.5 shows what happens when a few crystals of a dark purple dye called potassium permanganate are dropped into a beaker of water. The dye molecules diffuse into the water moving from high to low concentrations so they become evenly distributed throughout the beaker.
Diagram 3.5 : Diffusion in a liquid
In the body, diffusion causes molecules that are in a high concentration on one side of the cell membrane to move across the membrane until they are present in equal concentrations on both sides. It takes place because all molecules have an in-built vibration that causes them to move and collide until they are evenly distributed. It is an absolutely natural process that requires no added energy.
Small molecules like oxygen, carbon dioxide, water and ammonia as well as fats, diffuse directly through the double fat layer of the membrane. The small molecules named above as well as a variety of charged particles (ions) also diffuse through the protein-lined channels. Larger molecules like glucose attach to a carrier molecule that aids their diffusion through the membrane. This is called facilitated diffusion .
In the animal’s body diffusion is important for moving oxygen and carbon dioxide between the lungs and the blood, for moving digested food molecules from the gut into the blood and for the removal of waste products from the cell.
Osmosis
Although the word may be unfamiliar, you are almost certainly acquainted with the effects of osmosis. It is osmosis that plumps out dried fruit when you soak it before making a fruit cake or makes that wizened old carrot look almost like new when you soak it in water. Osmosis is in fact the diffusion of water across a membrane that allows water across but not larger molecules. This kind of membrane is called a semi-permeable membrane .
Diagram 3.6 : Osmosis
Take a look at side A of diagram 3.6. It shows a container divided into two parts by an artificial semi-permeable membrane. Water is poured into one part while a solution containing salt is poured into the other part. Water can cross the membrane but the salt cannot. The water crosses the semi-permeable membrane by diffusion until there is an equal amount of water on both sides of the membrane. The effect of this would be to make the salt solution more diluted and cause the level of the liquid in the right-hand side of the container to rise so it looked like side B of diagram 3.6. This movement of water across the semi-permeable membrane is called osmosis. It is a completely natural process that requires no outside energy.
Although it would be difficult to do in practice, imagine that you could now take a plunger and push down on the fluid in the right-hand side of container B so that it flowed back across the semi-permeable membrane until the level of fluid on both sides was equal again. If you could measure the pressure required to do this, this would be equal to the osmotic pressure of the salt solution. (This is a rather advanced concept at this stage but you will meet this term again when you study fluid balance later in the course).
Diagram 3.7 : Osmosis in red cells placed in a hypotonic solution
The plasma membrane of cells acts as a semi-permeable membrane. If red blood cells, for example, are placed in water, the water crosses the membrane to make the amount of water on both sides of it equal (see diagram 3.7). This means that the water moves into the cell causing it to swell. This can occur to such an extent that the cell actually bursts to release its contents. This bursting of red blood cells is called haemolysis . In a situation such as this when the solution on one side of a semi-permeable membrane has a lower concentration than that on the other side, the first solution is said to be hypotonic to the second.
Diagram 3.8 : Osmosis in red cells placed in a hypertonic solution
Now think what would happen if red blood cells were placed in a salt solution that has a higher salt concentration than the solution within the cells (see diagram 3.8). Such a bathing solution is called a hypertonic solution. In this situation the “concentration” of water within the cells would be higher than that outside the cells. Osmosis (diffusion of water) would then occur from the inside of the cells to the outside solution, causing the cells to shrink.
Diagram 3.9 : Red cells placed in an isotonic solution
A solution that contains 0.9% salt has the same concentration as body fluids and the solution within red cells. Cells placed in such a solution would neither swell nor shrink (see diagram 3.9). This solution is called an isotonic solution. This strength of salt solution is often called normal saline and is used when replacing an animal’s body fluids or when cells like red blood cells have to be suspended in fluid.
Remember - osmosis is a special kind of diffusion. It is the diffusion of water molecules across a semi-permeable membrane. It is a completely passive process and requires no energy.
Sometimes it is difficult to remember which way the water molecules move. Although it is not strictly true in a biological sense, many students use the phrase “SALT SUCKS” to help them remember which way water moves across the membrane when there are two solutions of different salt concentrations on either side.
As we have seen water moves in and out of the cell by osmosis. All water movement from the intestine into the blood system and between the blood capillaries and the fluid around the cells (tissue or extra cellular fluid) takes place by osmosis. Osmosis is also important in the production of concentrated urine by the kidney.
Active Transport
When a substance is transported from a low concentration to a high concentration i.e. uphill against the concentration gradient, energy has to be used. This is called active transport .
Active transport is important in maintaining different concentrations of the ions sodium and potassium on either side of the nerve cell membrane. It is also important for removing valuable molecules such as glucose, amino acids and sodium ions from the urine.
Diagram 3.10 : Phagocytosis
d) Phagocytosis
Phagocytosis is sometimes called “cell eating”. It is a process that requires energy and is used by cells to move solid particles like bacteria across the plasma membrane. Finger-like projections from the plasma membrane surround the bacteria and engulf them as shown in diagram 3.10. Once within the cell, enzymes produced by the lysosomes of the cell (described later) destroy the bacteria.
The destruction of bacteria and other foreign substance by white blood cells by the process of phagocytosis is a vital part of the defense mechanisms of the body.
e) Pinocytosis
Pinocytosis or “cell drinking” is a very similar process to phagocytosis but is used by cells to move fluids across the plasma membrane. Most cells carry out pinocytosis (note the pinocytotic vesicle in diagram 3.3).
f) Exocytosis
Exocytosis is the process by means of which substances formed in the cell are moved through the plasma membrane into the fluid outside the cell (or extra-cellular fluid). It occurs in all cells but is most important in secretory cells (e.g. cells that produce digestive enzymes) and nerve cells.