3.7: Barriers to Effective Communication
Effective communication skills and strategies are important for nurses. Clear communication means that information is conveyed effectively between the nurse, patients, family members and colleagues. However, it is recognized that such skills are not always evident and nurses do not always communicate well with patients, family members and colleagues. The message sent may not be the message received. The meaning of a message depends on its literal meaning, the non-verbal indicators accompanying it and the context in which it is delivered. It is therefore, easy to misinterpret the message, or to interpret it correctly, but to decide not to pursue its hidden meaning this leads to obstruction to communication. Continuous barriers to effective communication brings about a gradual breakdown in relationships. The barriers to effective communication outlined below will help nurses to understand the challenges [ 8 ].
Language Barrier
Language differences between the patient and the nurse are another preventive factor in effective communication. When the nurse and the patient do not share a common language, interaction between them is strained and very limited [ 9 , 10 , 11 ]. Consequently, a patient may fail to understand the instructions from a nurse regarding the frequency of taking medication at home.
Cultural Differences
Culture is another hindrance. The patient’s culture may block effective nurse–patient interactions because perceptions on health and death are different between patients [ 12 , 13 , 14 ]. The nurse needs to be sensitive when dealing with a patient from a different culture [ 9 , 15 , 16 ]. What is acceptable for one patient may not be acceptable for another. Given the complexity of culture, no one can possibly know the health beliefs and practices of every culture. The nurse needs check with the patient whether he/she prefers to be addressed by first name or surname. The use of eye contact, touching and personal space is different in various cultures and rules about eye contact are usually complex, varying according to race, social status and gender. Physical contact between sexes is strictly forbidden in some cultures and can include handshakes, hugging or placing a hand on the arm or shoulder. A ‘yes’ does not always mean ‘yes’. A smile does not indicate happiness, recognition or agreement. Whenever people communicate, there is a tendency to make value judgements regarding those perceived as being different. Past experiences can change the meaning of the message. Culture, background and bias can be good if they allow one to use past experiences to understand something new; it is when they change meaning of the message that they interfere with the communication process [ 12 ]. It is important for nurses to think about their own experiences when considering cultural differences in communication and how these can challenge health professionals and service users.
Conflict
Conflict is a common effect of two or more parties not sharing common ground. Conflict can be healthy in that it offers alternative views and values. However, it becomes a barrier to communication when the emotional ‘noise’ detracts from the task or purpose. Nurses aim for collaborative relationships with patients, families and colleagues.
Setting in Which Care is Provided
The factors in care setting may lead to reduction in quality of nurse–patient communication. Increased workload and time constraints restrict nurses from discussing their patients concerns effectively [ 16 ]. Nurses work in busy environments where they are expected to complete a specific amount of work in a day and work with a variety of other professionals, patients and their families. The roles are hard, challenging and tiring. There is a culture to get the work done. Some nurses may consider colleagues who spend time talking with patients to be avowing the ‘real’ work and lazy. Nurses who might have been confident in spending time with patients in an area where this was valued, when faced with a task-orientated culture have the dilemma of fitting into the group or being outside the group and spending time engaging with patients. Lack of collaboration between the nurses and the doctors in information sharing also hinder effective communication. This leads to inconsistencies in the information given to patients making comprehension difficult for the patient and their families.
Internal Noise, Mental/Emotional Distress
Internal noise has an impact on the communication process. Fear and anxiety can affect the person’s ability to listen to what the nurse is saying. People with feelings of fear and anger can find it difficult to hear. Illness and distress can alter a person’s thought processes. Reducing the cause of anxiety, distress, and anger would be the first step to improving communication.
Perception
If a healthcare professional feels that the person is talking too fast, not fluently, or does not articulate clearly etc., he/she may dismiss the person. Our preconceived attitudes affect our ability to listen. People tend to listen uncritically to people of high status and dismiss those of low status.
Difficulty With Speech and Hearing
People can experience difficulty in speech and hearing following conditions like stroke or brain injury. Stroke or trauma may affect brain areas that normally enable the individual to comprehend and produce speech, or the physiology that produces sound. These will present barriers to effective communication.
Medication
Medication can have a significant effect on communication for example it may cause dry mouth or excess salivation, nausea and indigestion, all of which influence the person’s ability and motivation to engage in conversation. If patients are embarrassed or concerned that they will not be able to speak properly or control their mouth, they could be reluctant to speak.
Noise
Equipment or environmental noise impedes clear communication. The sender and the receiver must both be able to concentrate on the messages they send to each other without any distraction.


5.5: Ready, Set, Start Your Own Business
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What are the first steps to take if you are starting your own business?
You have decided that you’d like to go into business for yourself. What is the best way to go about it? Start from scratch? Buy an existing business? Or buy a franchise? About 75 percent of business start-ups involve brand-new organizations, with the remaining 25 percent representing purchased companies or franchises. Franchising may have been discussed elsewhere in your course, so we’ll cover the other two options in this section.
Getting Started
The first step in starting your own business is a self-assessment to determine whether you have the personal traits you need to succeed and, if so, what type of business would be best for you. Table 5.6 provides a checklist to consider before starting your business.
Finding the Idea
Entrepreneurs get ideas for their businesses from many sources. It is not surprising that about 80 percent of Inc. 500 executives got the idea for their company while working in the same or a related industry. Starting a firm in a field where you have experience improves your chances of success. Other sources of inspiration are personal experiences as a consumer; hobbies and personal interests; suggestions from customers, family, and friends; industry conferences; and college courses or other education.
| Checklist for Starting a Business |
|---|
Before you start your own small business, consider the following checklist:
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Table 5.6 Source: “10 Steps to Start Your Business,” https://www.sba.gov , accessed February 2, 2018.
An excellent way to keep up with small-business trends is by reading entrepreneurship and small-business magazines and visiting their websites. With articles on everything from idea generation to selling a business, they provide an invaluable resource and profile some of the young entrepreneurs and their successful business ventures ( Table 5.7 ). 14
| Successful Entrepreneurs | |
|---|---|
| Name and Age | Company and Description |
| Philip Kimmey, 27 | Kimmey’s dog-sitting and dog-walking network, Rover.com, raised almost $100 million in venture capital and was valued at $300 million in 2017. |
| Max Mankin, 27 | Mankin cofounded Modern Electron and raised $10 million in venture capital to create “advanced thermionic energy converters” that will generate “cheap, scalable, and reliable electricity.” Modern Electron will turn every home into a power station. |
| Alexandra Cristin White, 28 | In her early 20s, White founded Glam Seamless, which sells tape-in hair extensions. In 2016, her self-funded company grossed $2.5 million. |
| Steph Korey, 29; Jen Rubio, 29 | Korey and Rubio founded Away, selling “first-class luggage at a coach price” in 2015. They raised $31 million in funding and grossed $12 million in sales in 2016. |
| Allen Gannet, 26 | Gannet founded TrackMaven, a web-marketing analytics company, in 2012; by 2016, his company was grossing $6.7 million a year. |
| Jake Kassan, 25; Kramer LaPlante, 25 | Kassan and Kramer launched their company, MVMT, through Indiegogo, raising $300,000, and in 2016 grossed $60 million, selling primarily watches and sunglasses. |
| Brian Streem, 29 | Streem’s company, Aerobo, provides drone services to the film industry, selling “professional aerial filming and drone cinematography.” Aerobo grossed $1 million in 2016, its first full year of business. |
| Natalya Bailey, 30; Louis Perna, 29 | Accion Systems began in 2014, raised $10 million in venture funding, and grossed $4.5 million in 2016, making tiny propulsion systems for satellites. |
| Jessy Dover, 29 | Dover is the cofounder of Dagne Dover, a company making storage-efficient handbags for professional women. She and her cofounders grossed $4.5 million in 2016 and debuted on Nordstrom.com in 2017. |
Table 5.7
These dynamic individuals, who are already so successful in their 20s and 30s, came up with unique ideas and concepts and found the right niche for their businesses.
Interesting ideas are all around you. Many successful businesses get started because someone identifies a need and then finds a way to fill it. Do you have a problem that you need to solve? Or a product that doesn’t work as well as you’d like? Raising questions about the way things are done and seeing opportunity in adversity are great ways to generate ideas.
Choosing a Form of Business Organization
A key decision for a person starting a new business is whether it will be a sole proprietorship, partnership, corporation, or limited liability company. As discussed earlier, each type of business organization has advantages and disadvantages. The choice depends on the type of business, number of employees, capital requirements, tax considerations, and level of risk involved.
Developing the Business Plan
Once you have the basic concept for a product or service, you must develop a plan to create the business. This planning process, culminating in a sound business plan , is one of the most important steps in starting a business. It can help to attract appropriate loan financing, minimize the risks involved, and be a critical determinant in whether a firm succeeds or fails. Many people do not venture out on their own because they are overwhelmed with doubts and concerns. A comprehensive business plan lets you run various “what if” analyses and evaluate your business without any financial outlay or risk. You can also develop strategies to overcome problems well before starting the business.
Taking the time to develop a good business plan pays off. A venture that seems sound at the idea stage may not look so good on paper. A well-prepared, comprehensive, written business plan forces entrepreneurs to take an objective and critical look at their business venture and analyze their concept carefully; make decisions about marketing, sales, operations, production, staffing, budgeting and financing; and set goals that will help them manage and monitor its growth and performance.
Exhibit 5.4 Each year, a variety of organizations hold business plan competitions to engage the growing number of college students starting their own businesses. The University of Essex and the iLearn entrepreneurship curriculum developed by the University of Texas in Austin, which partnered with Trisakti University in Jakarta, Indonesia, and the U.S. embassy to help run an entrepreneurship course and competition are examples of such competitions. Seven students from “iLearn: Entrepreneurship” were selected as finalists to pitch their business plans to a panel of Indonesian business leaders and embassy representatives. The winning business plan, which was an ecotourism concept, earned $1,000 in seed money. What research goes into a winning business plan? (Credit: University of Essex /flickr/ Attribution 2.0 Generic (CC BY 2.0))
The business plan also serves as the initial operating plan for the business. Writing a good business plan takes time. But many businesspeople neglect this critical planning tool in their eagerness to begin doing business, getting caught up in the day-to-day operations instead.
The key features of a business plan are a general description of the company, the qualifications of the owner(s), a description of the products or services, an analysis of the market (demand, customers, competition), sales and distribution channels, and a financial plan. The sections should work together to demonstrate why the business will be successful, while focusing on the uniqueness of the business and why it will attract customers. Table 5.8 describes the essential elements of a business plan.
A common use of a business plan is to persuade lenders and investors to finance the venture. The detailed information in the plan helps them assess whether to invest. Even though a business plan may take months to write, it must capture potential investors’ interest within minutes. For that reason, the basic business plan should be written with a particular reader in mind. Then you can fine-tune and tailor it to fit the investment goals of the investor(s) you plan to approach.
| Key Elements of a Business Plan |
|---|
| Executive summary provides an overview of the total business plan. Written after the other sections are completed, it highlights significant points and, ideally, creates enough excitement to motivate the reader to continue reading. |
| Vision and mission statement concisely describe the intended strategy and business philosophy for making the vision happen. Company values can also be included in this section. |
| Company overview explains the type of company, such as manufacturing, retail, or service; provides background information on the company if it already exists; and describes the proposed form of organization—sole proprietorship, partnership, or corporation. This section should include company name and location, company objectives, nature and primary product or service of the business, current status (start-up, buyout, or expansion) and history (if applicable), and legal form of organization. |
| Product and/or service plan describes the product and/or service and points out any unique features, as well as explains why people will buy the product or service. This section should offer the following descriptions: product and/or service; features and benefits of the product or service that provide a competitive advantage; available legal protection—patents, copyrights, and trademarks. |
| Marketing plan shows who the firm’s customers will be and what type of competition it will face; outlines the marketing strategy and specifies the firm’s competitive edge; and describes the strengths, weaknesses, opportunities, and threats of the business. This section should offer the following descriptions: analysis of target market and profile of target customer; methods of identifying, attracting, and retaining customers; a concise description of the value proposition; selling approach, type of sales force, and distribution channels; types of marketing and sales promotions, advertising, and projected marketing budget; product and/or service pricing strategy; and credit and pricing policies. |
| Management plan identifies the key players—active investors, management team, board members, and advisors— citing the experience and competence they possess. This section should offer the following descriptions: management team, outside investors and/or directors and their qualifications, outside resource people and their qualifications, and plans for recruiting and training employees. |
| Operating plan explains the type of manufacturing or operating system to be used and describes the facilities, labor, raw materials, and product-processing requirements. This section should offer the following descriptions: operating or manufacturing methods, operating facilities (location, space, and equipment), quality-control methods, procedures to control inventory and operations, sources of supply, and purchasing procedures. |
| Financial plan specifies financial needs and contemplated sources of financing, as well as presents projections of revenues, costs, and profits. This section should offer the following descriptions: historical financial statements for the last 3–5 years or as available; pro forma financial statements for 3–5 years, including income statements, balance sheets, cash flow statements, and cash budgets (monthly for first year and quarterly for second year); financial assumptions; breakeven analysis of profits and cash flows; and planned sources of financing. |
| Appendix of supporting documents provides materials supplementary to the plan. This section should offer the following descriptions: management team biographies; the company’s values; information about the company culture (if it’s unique and contributes to employee retention); and any other important data that support the information in the business plan, such as detailed competitive analysis, customer testimonials, and research summaries. |
Table 5.8 Sources: “7 Elements of a Business Plan,” https://quickbooks.intuit.com , accessed February 2, 2018; David Ciccarelli, “Write a Winning Business Plan with These 8 Key Elements,” Entrepreneur, https://www.entrepreneur.com , accessed February 2, 2018; Patrick Hull, “10 Essential Business Plan Components,” Forbes, https://www.forbes.com , accessed February 2, 2018; Justin G. Longenecker, J. William Petty, Leslie E. Palich, and Frank Hoy, Small Business Management: Launching & Growing Entrepreneurial Ventures, 18th edition (Mason, OH: Cengage, 2017); Monique Reece, Real-Time Marketing for Business Growth: How to Use Social Media, Measure Marketing, and Create a Culture of Execution (Upper Saddle River, NJ: FT Press/Pearson, 2010).
But don’t think you can set aside your business plan once you obtain financing and begin operating your company. Entrepreneurs who think their business plan is only for raising money make a big mistake. Business plans should be dynamic documents, reviewed and updated on a regular basis—monthly, quarterly, or annually, depending on how the business progresses and the particular industry changes.
Owners should adjust their sales and profit projections up or down as they analyze their markets and operating results. Reviewing your plan on a constant basis will help you identify strengths and weaknesses in your marketing and management strategies and help you evaluate possible opportunities for expansion in light of both your original mission and goals, current market trends, and business results. The Small Business Administration (SBA) offers sample business plans and online guidance for business plan preparation under the “Business Guide” tab at https://www.sba.gov .
Financing the Business
Once the business plan is complete, the next step is to obtain financing to set up your company. The funding required depends on the type of business and the entrepreneur’s own investment. Businesses started by lifestyle entrepreneurs require less financing than growth-oriented businesses, and manufacturing and high-tech companies generally require a large initial investment.
Who provides start-up funding for small companies? Like Miho Inagi and her Tokyo bagel shop, 94 percent of business owners raise start-up funds from personal accounts, family, and friends. Personal assets and money from family and friends are important for new firms, whereas funding from financial institutions may become more important as companies grow. Three-quarters of Inc . 500 companies have been funded on $100,000 or less. 15
The two forms of business financing are debt , borrowed funds that must be repaid with interest over a stated time period, and equity , funds raised through the sale of stock (i.e., ownership) in the business. Those who provide equity funds get a share of the business’s profits. Because lenders usually limit debt financing to no more than a quarter to a third of the firm’s total needs, equity financing often amounts to about 65 to 75 percent of total start-up financing.
Exhibit 5.5 FUBU started when a young entrepreneur from Hollis, Queens, began making tie-top skullcaps at home with some friends. With funding from a $100,000 mortgage and a later investment from the Samsung Corporation, CEO Daymond John, turned his home into a successful sportswear company. The FUBU brand tops the list for today’s fashionistas who don everything from FUBU’s classic Fat Albert line to swanky FUBU suits and tuxedos. How do start-ups obtain funding? (Credit: U.S. Embasy Nairobi/ flickr/ Attribution 2.0 Generic (CC BY 2.0))
One way to finance a start-up company is bootstrapping, which is basically funding the operation with your own resources. If the resources needed are not available to an individual, there are other options. Two sources of equity financing for young companies are angel investors and venture-capital firms. Angel investors are individual investors or groups of experienced investors who provide financing for start-up businesses by investing their own money, often referred to as “seed capital.” This gives the investors more flexibility on what they can and will invest in, but because it is their own money, angels are careful. Angel investors often invest early in a company’s development, and they want to see an idea they understand and can have confidence in. Table 5.9 offers some guidelines on how to attract angel financing.
| Making a Heavenly Deal |
|---|
You need financing for your start-up business. How do you get angels interested in investing in your business venture?
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Table 5.9 Sources: Guy Kawasaki, “The Art of Raising Angel Capital,” https://guykawasaki.com , accessed February 2, 2018; Murray Newlands, “How to Raise an Angel Funding Round,” Forbes, https://www.forbes.com , March 16, 2017; Melinda Emerson, “5 Tips for Attracting Angel Investors,” Small Business Trends, https://smallbiztrends.com , July 26, 2016; Nicole Fallon, “5 Tips for Attracting Angel Investors,” Business News Daily, https://www.businessnewsdaily.com , January 2, 2014; Stacy Zhao, “9 Tips for Winning over Angels,” Inc., https://www.inc.com , June 15, 2005; Rhonda Abrams, “What Does It Take to Impress an Angel Investor?” Inc., https://www.inc.com , March 29, 2001.
Venture capital is financing obtained from venture capitalists, investment firms that specialize in financing small, high-growth companies. Venture capitalists receive an ownership interest and a voice in management in return for their money. They typically invest at a later stage than angel investors. We’ll discuss venture capital in greater detail when discussing financing the enterprise.
Buying a Small Business
Another route to small-business ownership is buying an existing business. Although this approach is less risky, many of the same steps for starting a business from scratch apply to buying an existing company. It still requires careful and thorough analysis. The potential buyer must answer several important questions: Why is the owner selling? Does he or she want to retire or move on to a new challenge, or are there problems with the business? Is the business operating at a profit? If not, can this be corrected? On what basis has the owner valued the company, and is it a fair price? What are the owner’s plans after selling the company? Will he or she be available to provide assistance through the change of ownership of the business? And depending on the type of business it is, will customers be more loyal to the owner than to the product or service being offered? Customers could leave the firm if the current owner decides to open a similar business. To protect against this, many purchasers include a noncompete clause in the contract of sale, which generally means that the owner of the company being sold may not be allowed to compete in the same industry of the acquired business for a specific amount of time.
You should prepare a business plan that thoroughly analyzes all aspects of the business. Get answers to all your questions, and determine, via the business plan, whether the business is a sound one. Then you must negotiate the price and other terms of purchase and obtain appropriate financing. This can be a complicated process and may require the use of a consultant or business broker.
Risky Business
Running your own business may not be as easy as it sounds. Despite the many advantages of being your own boss, the risks are great as well. Over a period of five years, nearly 50% percent of small businesses fail according to the Kauffman Foundation. 16
Businesses close down for many reasons—and not all are failures. Some businesses that close are financially successful and close for nonfinancial reasons. But the causes of business failure can be interrelated. For example, low sales and high expenses are often directly related to poor management. Some common causes of business closure are:
- Economic factors—business downturns and high interest rates
- Financial causes—inadequate capital, low cash balances, and high expenses
- Lack of experience—inadequate business knowledge, management experience, and technical expertise
- Personal reasons—the owners may decide to sell the business or move on to other opportunities
Inadequate early planning is often at the core of later business problems. As described earlier, a thorough feasibility analysis, from market assessment to financing, is critical to business success. Yet even with the best plans, business conditions change and unexpected challenges arise. An entrepreneur may start a company based on a terrific new product only to find that a larger firm with more marketing, financing, and distribution clout introduces a similar item.
The stress of managing a business can also take its toll. The business can consume your whole life. Owners may find themselves in over their heads and unable to cope with the pressures of business operations, from the long hours to being the main decision maker. Even successful businesses have to deal with ongoing challenges. Growing too quickly can cause as many problems as sluggish sales. Growth can strain a company’s finances when additional capital is required to fund expanding operations, from hiring additional staff to purchasing more raw material or equipment. Successful business owners must respond quickly and develop plans to manage its growth.
So, how do you know when it is time to quit? “Never give up” may be a good motivational catchphrase, but it is not always good advice for a small-business owner. Yet, some small-business owners keep going no matter what the cost. For example, Ian White’s company was trying to market a new kind of city map. White maxed out 11 credit cards and ran up more than $100,000 in debt after starting his company. He ultimately declared personal bankruptcy and was forced to find a job so that he could pay his bills. Maria Martz didn’t realize her small business would become a casualty until she saw her tax return showing her company’s losses in black and white—for the second year in a row. It convinced her that enough was enough and she gave up her gift-basket business to become a full-time homemaker. But once the decision is made, it may be tough to stick to. “I got calls from people asking how come I wasn’t in business anymore. It was tempting to say I’d make their basket but I had to tell myself it is finished now.” 17
CONCEPT CHECK
- How can potential business owners find new business ideas?
- Why is it important to develop a business plan? What should such a plan include?
- What financing options do small-business owners have? What risks do they face?


5.2: Bone Formation and Development
In the early stages of embryonic development, the embryo’s skeleton consists of fibrous membranes and hyaline cartilage. By the sixth or seventh week of embryonic life, the actual process of bone development, ossification (osteogenesis), begins. There are two osteogenic pathways—intramembranous ossification and endochondral ossification—but bone is the same regardless of the pathway that produces it.
Cartilage Templates
Bone is a replacement tissue; that is, it uses a model tissue on which to lay down its mineral matrix. For skeletal development, the most common template is cartilage. During fetal development, a framework is laid down that determines where bones will form. This framework is a flexible, semi-solid matrix produced by chondroblasts and consists of hyaluronic acid, chondroitin sulfate, collagen fibers, and water. As the matrix surrounds and isolates chondroblasts, they are called chondrocytes. Unlike most connective tissues, cartilage is avascular, meaning that it has no blood vessels supplying nutrients and removing metabolic wastes. All of these functions are carried on by diffusion through the matrix. This is why damaged cartilage does not repair itself as readily as most tissues do.
Throughout fetal development and into childhood growth and development, bone forms on the cartilaginous matrix. By the time a fetus is born, most of the cartilage has been replaced with bone. Some additional cartilage will be replaced throughout childhood, and some cartilage remains in the adult skeleton.
Intramembranous Ossification
During intramembranous ossification , compact and spongy bone develops directly from sheets of mesenchymal (undifferentiated) connective tissue. The flat bones of the face, most of the cranial bones, and the clavicles (collarbones) are formed via intramembranous ossification.
The process begins when mesenchymal cells in the embryonic skeleton gather together and begin to differentiate into specialized cells (Figure 6.16a). Some of these cells will differentiate into capillaries, while others will become osteogenic cells and then osteoblasts. Although they will ultimately be spread out by the formation of bone tissue, early osteoblasts appear in a cluster called an ossification center .
The osteoblasts secrete osteoid , uncalcified matrix, which calcifies (hardens) within a few days as mineral salts are deposited on it, thereby entrapping the osteoblasts within. Once entrapped, the osteoblasts become osteocytes (Figure 6.16b). As osteoblasts transform into osteocytes, osteogenic cells in the surrounding connective tissue differentiate into new osteoblasts.
Osteoid (unmineralized bone matrix) secreted around the capillaries results in a trabecular matrix, while osteoblasts on the surface of the spongy bone become the periosteum (Figure 6.16 c ). The periosteum then creates a protective layer of compact bone superficial to the trabecular bone. The trabecular bone crowds nearby blood vessels, which eventually condense into red marrow (Figure 6.16 d ).
Intramembranous ossification begins in utero during fetal development and continues on into adolescence. At birth, the skull and clavicles are not fully ossified nor are the sutures of the skull closed. This allows the skull and shoulders to deform during passage through the birth canal. The last bones to ossify via intramembranous ossification are the flat bones of the face, which reach their adult size at the end of the adolescent growth spurt.
Endochondral Ossification
In endochondral ossification , bone develops by replacing hyaline cartilage. Cartilage does not become bone. Instead, cartilage serves as a template to be completely replaced by new bone. Endochondral ossification takes much longer than intramembranous ossification. Bones at the base of the skull and long bones form via endochondral ossification.
In a long bone, for example, at about 6 to 8 weeks after conception, some of the mesenchymal cells differentiate into chondrocytes (cartilage cells) that form the cartilaginous skeletal precursor of the bones (Figure 6.17a). Soon after, the perichondrium , a membrane that covers the cartilage, appears Figure 6.17b).
As more matrix is produced, the chondrocytes in the center of the cartilaginous model grow in size. As the matrix calcifies, nutrients can no longer reach the chondrocytes. This results in their death and the disintegration of the surrounding cartilage. Blood vessels invade the resulting spaces, not only enlarging the cavities but also carrying osteogenic cells with them, many of which will become osteoblasts. These enlarging spaces eventually combine to become the medullary cavity.
As the cartilage grows, capillaries penetrate it. This penetration initiates the transformation of the perichondrium into the bone-producing periosteum. Here, the osteoblasts form a periosteal collar of compact bone around the cartilage of the diaphysis. By the second or third month of fetal life, bone cell development and ossification ramps up and creates the primary ossification center , a region deep in the periosteal collar where ossification begins (Figure 6.17 c ).
While these deep changes are occurring, chondrocytes and cartilage continue to grow at the ends of the bone (the future epiphyses), which increases the bone’s length at the same time bone is replacing cartilage in the diaphyses. By the time the fetal skeleton is fully formed, cartilage only remains at the joint surface as articular cartilage and between the diaphysis and epiphysis as the epiphyseal plate, the latter of which is responsible for the longitudinal growth of bones. After birth, this same sequence of events (matrix mineralization, death of chondrocytes, invasion of blood vessels from the periosteum, and seeding with osteogenic cells that become osteoblasts) occurs in the epiphyseal regions, and each of these centers of activity is referred to as a secondary ossification center (Figure 6.17 e ).
How Bones Grow in Length
The epiphyseal plate is the area of growth in a long bone. It is a layer of hyaline cartilage where ossification occurs in immature bones. On the epiphyseal side of the epiphyseal plate, cartilage is formed. On the diaphyseal side, cartilage is ossified, and the diaphysis grows in length. The epiphyseal plate is composed of four zones of cells and activity (Figure 6.18). The reserve zone is the region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix. These chondrocytes do not participate in bone growth but secure the epiphyseal plate to the osseous tissue of the epiphysis.
The proliferative zon e is the next layer toward the diaphysis and contains stacks of slightly larger chondrocytes. It makes new chondrocytes (via mitosis) to replace those that die at the diaphyseal end of the plate. Chondrocytes in the next layer, the zone of maturation and hypertrophy , are older and larger than those in the proliferative zone. The more mature cells are situated closer to the diaphyseal end of the plate. The longitudinal growth of bone is a result of cellular division in the proliferative zone and the maturation of cells in the zone of maturation and hypertrophy.
Most of the chondrocytes in the zone of calcified matrix , the zone closest to the diaphysis, are dead because the matrix around them has calcified. Capillaries and osteoblasts from the diaphysis penetrate this zone, and the osteoblasts secrete bone tissue on the remaining calcified cartilage. Thus, the zone of calcified matrix connects the epiphyseal plate to the diaphysis. A bone grows in length when osseous tissue is added to the diaphysis.
Bones continue to grow in length until early adulthood. The rate of growth is controlled by hormones, which will be discussed later. When the chondrocytes in the epiphyseal plate cease their proliferation and bone replaces the cartilage, longitudinal growth stops. All that remains of the epiphyseal plate is the epiphyseal line (Figure 6.19).
How Bones Grow in Diameter
While bones are increasing in length, they are also increasing in diameter; growth in diameter can continue even after longitudinal growth ceases. This is called appositional growth. Osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts, via intramembranous ossification, produce new bone tissue beneath the periosteum. The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity. This process is called modeling .
Bone Remodeling
The process in which matrix is resorbed on one surface of a bone and deposited on another is known as bone modeling. Modeling primarily takes place during a bone’s growth. However, in adult life, bone undergoes remodeling , in which resorption of old or damaged bone takes place on the same surface where osteoblasts lay new bone to replace that which is resorbed. Injury, exercise, and other activities lead to remodeling. Those influences are discussed later in the chapter, but even without injury or exercise, about 5 to 10 percent of the skeleton is remodeled annually just by destroying old bone and renewing it with fresh bone.
Diseases of the Skeletal System
Osteogenesis imperfecta (OI) is a genetic disease in which bones do not form properly and therefore are fragile and break easily. It is also called brittle bone disease. The disease is present from birth and affects a person throughout life.
The genetic mutation that causes OI affects the body’s production of collagen, one of the critical components of bone matrix. The severity of the disease can range from mild to severe. Those with the most severe forms of the disease sustain many more fractures than those with a mild form. Frequent and multiple fractures typically lead to bone deformities and short stature. Bowing of the long bones and curvature of the spine are also common in people afflicted with OI. Curvature of the spine makes breathing difficult because the lungs are compressed.
Because collagen is such an important structural protein in many parts of the body, people with OI may also experience fragile skin, weak muscles, loose joints, easy bruising, frequent nosebleeds, brittle teeth, blue sclera, and hearing loss. There is no known cure for OI. Treatment focuses on helping the person retain as much independence as possible while minimizing fractures and maximizing mobility. Toward that end, safe exercises, like swimming, in which the body is less likely to experience collisions or compressive forces, are recommended. Braces to support legs, ankles, knees, and wrists are used as needed. Canes, walkers, or wheelchairs can also help compensate for weaknesses.
When bones do break, casts, splints, or wraps are used. In some cases, metal rods may be surgically implanted into the long bones of the arms and legs. Research is currently being conducted on using bisphosphonates to treat OI. Smoking and being overweight are especially risky in people with OI, since smoking is known to weaken bones, and extra body weight puts additional stress on the bones.
Watch this video to see how a bone grows.
Contributors and Attributions
- Chapter 6. Authored by : OpenStax College. Provided by : Rice University. Located at : http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22<EMAIL_ADDRESS>. Project : Anatomy & Physiology. License : CC BY: Attribution . License Terms : Download for free at http://cnx.org/content/col11496/latest/ .


1.3: Politics of Reconstruction
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Reconstruction—the effort to restore southern states to the Union and to redefine African Americans’ place in American society—began before the Civil War ended. President Abraham Lincoln began planning for the reunification of the United States in the fall of 1863. 2 With a sense that Union victory was imminent and that he could turn the tide of the war by stoking Unionist support in the Confederate states, Lincoln issued a proclamation allowing southerners to take an oath of allegiance. When just 10 percent of a state’s voting population had taken such an oath, loyal Unionists could then establish governments. 3 These so-called Lincoln governments sprang up in pockets where Union support existed like Louisiana, Tennessee, and Arkansas. Unsurprisingly, these were also the places that were exempted from the liberating effects of the Emancipation Proclamation.
Initially proposed as a war aim, Lincoln’s Emancipation Proclamation committed the United States to the abolition of slavery. However, the proclamation freed only slaves in areas of rebellion and left more than seven hundred thousand in bondage in Delaware, Kentucky, Maryland, and Missouri as well as in Union-occupied areas of Louisiana, Tennessee, and Virginia.
To cement the abolition of slavery, Congress passed the Thirteenth Amendment on January 31, 1865. The amendment legally abolished slavery “except as a punishment for crime whereof the party shall have been duly convicted.” Section Two of the amendment granted Congress the “power to enforce this article by appropriate legislation.” State ratification followed, and by the end of the year the requisite three fourths of the states had approved the amendment, and four million people were forever free from the slavery that had existed in North America for 250 years. 4
Lincoln’s policy was lenient, conservative, and short-lived. Reconstruction changed when John Wilkes Booth shot Lincoln on April 14, 1865, during a performance of Our American Cousin at Ford’s Theater. Treated rapidly and with all possible care, Lincoln nevertheless succumbed to his wounds the following morning, leaving a somber pall over the North and especially among African Americans.
The assassination of Abraham Lincoln propelled Vice President Andrew Johnson into the executive office in April 1865. Johnson, a states’-rights, strict-constructionist, and unapologetic racist from Tennessee, offered southern states a quick restoration into the Union. His Reconstruction plan required provisional southern governments to void their ordinances of secession, repudiate their Confederate debts, and ratify the Thirteenth Amendment. On all other matters, the conventions could do what they wanted with no federal interference. He pardoned all southerners engaged in the rebellion with the exception of wealthy planters who possessed more than $20,000 in property. 5 The southern aristocracy would have to appeal to Johnson for individual pardons. In the meantime, Johnson hoped that a new class of southerners would replace the extremely wealthy in leadership positions.
Many southern governments enacted legislation that reestablished antebellum power relationships. South Carolina and Mississippi passed laws known as Black Codes to regulate black behavior and impose social and economic control. These laws granted some rights to African Americans, like the right to own property, to marry, or to make contracts. But they also denied fundamental rights. White lawmakers forbade black men from serving on juries or in state militias, refused to recognize black testimony against white people, apprenticed orphaned children to their former masters, and established severe vagrancy laws. Mississippi’s vagrant law required all freedmen to carry papers proving they had means of employment. 6 If they had no proof, they could be arrested and fined. If they could not pay the fine, the sheriff had the right to hire out his prisoner to anyone who was willing to pay the tax. Similar ambiguous vagrancy laws throughout the South reasserted control over black labor in what one scholar has called “slavery by another name.” 7 Black codes effectively criminalized black people’s leisure, limited their mobility, and locked many into exploitative farming contracts. Attempts to restore the antebellum economic order largely succeeded.
These laws and outrageous mob violence against black southerners led Republicans to call for a more dramatic Reconstruction. So when Johnson announced that the southern states had been restored, congressional Republicans refused to seat delegates from the newly reconstructed states.
Republicans in Congress responded with a spate of legislation aimed at protecting freedmen and restructuring political relations in the South. Many Republicans were keen to grant voting rights for freedmen in order to build a new powerful voting bloc. Some Republicans, like U.S. congressman Thaddeus Stevens, believed in racial equality, but the majority were motivated primarily by the interest of their political party. The only way to protect Republican interests in the South was to give the vote to the hundreds of thousands of black men. Republicans in Congress responded to the codes with the Civil Rights Act of 1866, the first federal attempt to constitutionally define all American-born residents (except Native peoples) as citizens. The law also prohibited any curtailment of citizens’ “fundamental rights.” 8
The Fourteenth Amendment developed concurrently with the Civil Rights Act to ensure its constitutionality. The House of Representatives approved the Fourteenth Amendment on June 13, 1866. Section One granted citizenship and repealed the Taney Court’s infamous Dred Scott (1857) decision. Moreover, it ensured that state laws could not deny due process or discriminate against particular groups of people. The Fourteenth Amendment signaled the federal government’s willingness to enforce the Bill of Rights over the authority of the states.
Because he did not believe African Americans deserved equal rights, President Johnson opposed the passage of the Fourteenth Amendment and vetoed the Civil Rights Act. But after winning a two-thirds majority in the 1866 midterm elections, Republicans overrode the veto, and in 1867, they passed the first Reconstruction Act, dissolving state governments and dividing the South into five military districts. Under these new terms, states would have to ratify the Fourteenth Amendment, write new constitutions enfranchising African Americans, and abolish repressive “black codes” before rejoining the union. In the face of President Johnson’s repeated obstructionism, the House of Representatives issued articles of impeachment against the president. Although Johnson narrowly escaped conviction in the Senate, Congress won the power to direct a new phase of Reconstruction. Six weeks later, on July 9, 1868, the states ratified the Fourteenth Amendment, guaranteeing birthright citizenship and “equal protection of the laws.
In the 1868 presidential election, former Union General Ulysses S. Grant ran on a platform that proclaimed, “Let Us Have Peace,” in which he promised to protect the new status quo. On the other hand, the Democratic candidate, Horatio Seymour, promised to repeal Reconstruction. Black southern voters helped Grant win most of the former Confederacy.
Reconstruction brought the first moment of mass democratic participation for African Americans. In 1860, only five states in the North allowed African Americans to vote on equal terms with whites. Yet after 1867, when Congress ordered southern states to eliminate racial discrimination in voting, African Americans began to win elections across the South. In a short time, the South was transformed from an all-white, pro-slavery, Democratic stronghold to a collection of Republican-led states with African Americans in positions of power for the first time in American history. 9
Through the provisions of the congressional Reconstruction Acts, black men voted in large numbers and also served as delegates to the state constitutional conventions in 1868. Black delegates actively participated in revising state constitutions. One of the most significant accomplishments of these conventions was the establishment of a public school system. While public schools were virtually nonexistent in the antebellum period, by the end of Reconstruction, every southern state had established a public school system. 10 Republican officials opened state institutions like mental asylums, hospitals, orphanages, and prisons to white and black residents, though often on a segregated basis. They actively sought industrial development, northern investment, and internal improvements.
African Americans served at every level of government during Reconstruction. At the federal level, Hiram Revels and Blanche K. Bruce were chosen as U.S. senators from Mississippi. Fourteen men served in the House of Representatives. At least 270 other African American men served in patronage positions as postmasters, customs officials, assessors, and ambassadors. At the state level, more than 1,000 African American men held offices in the South. P. B. S. Pinchback served as Louisiana’s governor for thirty-four days after the previous governor was suspended during impeachment proceedings and was the only African American state governor until Virginia elected L. Douglas Wilder in 1989. Almost 800 African American men served as state legislators around the South, with African Americans at one time making up a majority in the South Carolina House of Representatives. 11
African American officeholders came from diverse backgrounds. Many had been born free or had gained their freedom before the Civil War. Many free African Americans, particularly those in South Carolina, Virginia, and Louisiana, were wealthy and well educated, two facts that distinguished them from much of the white population both before and after the Civil War. Some, like Antoine Dubuclet of Louisiana and William Breedlove from Virginia, owned slaves before the Civil War. Others had helped slaves escape or taught them to read, like Georgia’s James D. Porter.
Most African American officeholders, however, gained their freedom during the war. Among them were skilled craftsmen like Emanuel Fortune, a shoemaker from Florida; ministers such as James D. Lynch from Mississippi; and teachers like William V. Turner from Alabama. Moving into political office was a natural continuation of the leadership roles they had held in their former slave communities.
By the end of Reconstruction in 1877, more than two thousand African American men had served in offices ranging from local levee commissioner to U.S. senator. 12 When the end of Reconstruction returned white Democrats to power in the South, all but a few African American officeholders lost their positions. After Reconstruction, African Americans did not enter the political arena again in large numbers until well into the twentieth century.


3: C3) Vector Analysis
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- 3.1: Coordinate Systems and Components of a Vector (Part 1)
- The vector component is the product of the unit vector of an axis with its scalar component along that axis. A vector is the resultant of its vector components. The scalar x-component of a vector can be expressed as the product of its magnitude with the cosine of its direction angle, and the scalar y-component can be expressed as the product of its magnitude with the sine of its direction angle.
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- 3.2: Coordinate Systems and Components of a Vector (Part 2)
- In a plane, there are two equivalent coordinate systems. The Cartesian coordinate system is defined by unit vectors i^ and j^ along the x-axis and the y-axis, respectively. The polar coordinate system is defined by the radial unit vector r^, which gives the direction from the origin, and a unit vector t^, which is perpendicular (orthogonal) to the radial direction.
The language of physics is mathematics. This is not just a thing we tell ourselves, but is a basic fact that separates the physical sciences from the social sciences. Although we may speak and write about physics using a spoken and written language (English, in this case), this is just for descriptive convenience. Anytime we actually want to do anything with physics, we have to cast it into mathematics. Part of this is a desire for precision - if I say "the acceleration due to gravity is 9.81 m/s\(^2\)", I know exactly how precise that number is (typically we assume the uncertainty is in the last decimal point, so that implies \( \pm 0.01~m/s^2\) on that number). However, it's also a necessity, since no amount of words can actually be used to exactly describe any physical law, and words don't inherently have precise meaning. Take even the most basic of physical laws - Newton's first law "An object in motion remains in motion until acted on by an external force." What is "motion"? What does it mean to be "acted on"? What is "force"? No amount of language is going to answer these questions, only mathematics is going to give us careful definitions of these concepts 1 .
So, once we are convinced that we need to use mathematics to do physics, we know that we need to understand how to associate physics quantities ("mass", "speed", "force") with mathematical variables. In some cases, this is very easy - for example, the temperature of something is just a number, call it \(T\). Or the mass of something is a number \(m\). Single numbers are called scalars . Sometimes these numbers have constraints on them that come from reality - for example, mass must be positive, and temperature has a minimum value (absolute zero). But there are also quantities which need more than just a single variable, or additional conditions on that variable - they actually must carry more information. The most important of these are vectors , which carry both a number (the magnitude , or length of the vector), and a direction .
The length of a vector is a pretty straightforward idea - vectors are arrows, and the size of the arrow is the length. But direction is a little bit more confusing, because it can be specified in several different ways. For example, I can be driving at a speed of 32 mph, in the direction "north". Or maybe in the direction "towards you", or "90\(^{\circ}\) from East". Because of this uncertainty, we will often choose to represent vectors using components - that is, an \(xy\)-Cartesian coordinate system. Of course, this coordinate system is something we created out of thin air to help us solve the problem, so which coordinate system we pick should not influence our calculation in the slightest.
For a concrete example, consider a vector of length 5, that is pointed \(45^{\circ}\) above the horizontal (see the figure on bottom left). We can choose to represent this vector in a number of ways. In a coordinate system fixed to the horizontal, the vector has components
\[v_x=5\cos(45)\simeq 3.53, v_y=5\sin(45)\simeq 3.53.\]
Alternatively, if you pick a coordinate system with the x-axis along the vector itself (figure on bottom middle), the components would be
\[v_x=5, v_y=0.\]
In some cases one of these might be preferable to the other, but there is something important here: although the coordinate representation changed, the magnitude and direction did not . No choice of coordinate system can change the magnitude and direction of a physical variable like a vector, because coordinates are just helping tools to do physics.
There is one last point to make about vectors in coordinate systems, which is summed up by the last figure: performing mathematics like addition on vectors means the same mathematics applies to the components. This makes working with components very convenient - we don't actually need to go around making pictures of arrows and measuring them, we can just use the components and get the results algebraically.
1 If you're interested, the mathematical statement of Newton's first law is something like "\( \vec{a}=0 \supset \Sigma \vec{F}_{ext}=0\)", using the symbol \(\supset\) for "if".


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age of consent
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minimum age at which an individual can legally make decisions to engage in sexual behavior
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body image
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our mental image or representation of our body
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clique
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close group of three to a dozen or so friends
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crowd
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large social grouping of many dozens or more members in the social milieu of adolescents
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cultural heritage
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adaptations to the natural and social world that have shared meaning and are passed from generation to generation
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de-idealization
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tendency of adolescents to see a mismatch between the values their parents proclaim, the rules they put forward, and the way imperfect parents lead their own imperfect lives
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friendship
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intimate, emotionally close relationship between two individuals
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gender intensification hypothesis
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prediction that conforming to gender roles is of heightened relevance during adolescence
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gender nonconforming behavior
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behavior that does not match society’s expectations for the individual’s assigned gender
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heteronormativity
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idea that heterosexuality is the norm or preferred sexual orientation and that opposite-sex people are best suited for sexual and marital relationships
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identity
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individual’s complete sense of who they are, including their traits, capabilities, interests, values, and social roles
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identity achievement
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realization and commitment to a coherent understanding of oneself and our relationship with society after exploring various identities
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identity diffusion
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identity status in which the individual has low commitment and does not actively seek an identity; most closely aligns with Erikson’s role confusion
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identity foreclosure
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identity status in which an individual has shown an early commitment to an identity without any prior exploration
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identity moratorium
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stage in which individuals are actively exploring various identities but not declaring an identity to be fully formed
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identity versus role confusion
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fifth stage of Erikson’s psychosocial development, which involves forming a stable and whole identity by first exploring various roles and identities
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possible selves
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various identities toward which adolescents may work in the future
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relational aggression
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practice of including or excluding others or otherwise threatening a sense of belonging such as by spreading gossip
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rite of passage
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socially or culturally explicit markers to recognize the transitioning adolescent’s progress and achievement of adult status in one or more dimensions
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romantic relationship
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bond psychologically distinct from mere liking and including components of affection, intimacy, exclusivity, and interdependence
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stereotype threat
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phenomenon where individuals experience anxiety or fear of confirming negative stereotypes about their social group, which can impair their performance in academic or other achievement-related tasks


7.6B: The Protein Synthesis Machinery
Protein synthesis, or translation of mRNA into protein, occurs with the help of ribosomes, tRNAs, and aminoacyl tRNA synthetases.
LEARNING OBJECTIVES
Explain the role played by ribosomes, tRNA, and aminoacyl tRNA synthetases in protein synthesis
Key Takeaways
The Protein Synthesis Machinery
In addition to the mRNA template, many molecules and macromolecules contribute to the process of translation. The composition of each component may vary across species. For instance, ribosomes may consist of different numbers of rRNAs and polypeptides depending on the organism. However, the general structures and functions of the protein synthesis machinery are comparable from bacteria to archaea to human cells. Translation requires the input of an mRNA template, ribosomes, tRNAs, and various enzymatic factors.
Ribosomes
A ribosome is a complex macromolecule composed of structural and catalytic rRNAs, and many distinct polypeptides. In eukaryotes, the synthesis and assembly of rRNAs occurs in the nucleolus.
Ribosomes exist in the cytoplasm in prokaryotes and in the cytoplasm and on rough endoplasmic reticulum membranes in eukaryotes. Mitochondria and chloroplasts also have their own ribosomes, and these look more similar to prokaryotic ribosomes (and have similar drug sensitivities) than the cytoplasmic ribosomes. Ribosomes dissociate into large and small subunits when they are not synthesizing proteins and reassociate during the initiation of translation. E. coli have a 30S small subunit and a 50S large subunit, for a total of 70S when assembled (recall that Svedberg units are not additive).  The small subunit is responsible for binding the mRNA template, whereas the large subunit sequentially binds tRNAs.
In bacteria, archaea, and eukaryotes, the intact ribosome has three binding sites that accomodate tRNAs: The A site, the P site, and the E site. Incoming aminoacy-tRNAs (a tRNA with an amino acid covalently attached is called an aminoacyl-tRNA) enter the ribosome at the A site. The peptidyl-tRNA carrying the growing polypeptide chain is held in the P site. The E site holds empty tRNAs just before they exit the ribosome.
Each mRNA molecule is simultaneously translated by many ribosomes, all reading the mRNA from 5′ to 3′ and synthesizing the polypeptide from the N terminus to the C terminus. The complete mRNA/poly-ribosome structure is called a polysome.
tRNAs in eukaryotes
The tRNA molecules are transcribed by RNA polymerase III. Depending on the species, 40 to 60 types of tRNAs exist in the cytoplasm. Specific tRNAs bind to codons on the mRNA template and add the corresponding amino acid to the polypeptide chain. (More accurately, the growing polypeptide chain is added to each new amino acid bound in by a tRNA.)
The transfer RNAs (tRNAs) are structural RNA molecules. In eukaryotes, tRNA mole are transcribed from tRNA genes by RNA polymerase III. Depending on the species, 40 to 60 types of tRNAs exist in the cytoplasm. Serving as adaptors, specific tRNAs bind to sequences on the mRNA template and add the corresponding amino acid to the polypeptide chain. (More accurately, the growing polypeptide chain is added to each new amino acid brought in by a tRNA.) Therefore, tRNAs are the molecules that actually “translate” the language of RNA into the language of proteins.
Of the 64 possible mRNA codons (triplet combinations of A, U, G, and C) three specify the termination of protein synthesis and 61 specify the addition of amino acids to the polypeptide chain. Of the three termination codons, one (UGA) can also be used to encode the 21st amino acid, selenocysteine, but only if the mRNA contains a specific sequence of nucleotides known as a SECIS sequence. Of the 61 non-termination codons, one codon (AUG) also encodes the initiation of translation.
Each tRNA polynucleotide chain folds up so that some internal sections basepair with other internal sections. If just diagrammed in two dimensions, the regions where basepairing occurs are called stems, and the regions where no basepairs form are called loops, and the entire pattern of stems and loops that forms for a tRNA is called the “cloverleaf” structure. All tRNAs fold into very similar cloverleaf structures of four major stems and three major loops.
If viewed as a three-dimensional structure, all the basepaired regions of the tRNA are helical, and the tRNA folds into a L-shaped structure.
Each tRNA has a sequence of three nucleotides located in a loop at one end of the molecule that can basepair with an mRNA codon. This is called the tRNA’s anticodon. Each different tRNA has a different anticodon. When the tRNA anticodon basepairs with one of the mRNA codons, the tRNA will add an amino acid to a growing polypeptide chain or terminate translation, according to the genetic code. For instance, if the sequence CUA occurred on a mRNA template in the proper reading frame, it would bind a tRNA with an anticodon expressing the complementary sequence, GAU. The tRNA with this anticodon would be linked to the amino acid leucine.
Aminoacyl tRNA Synthetases
The process of pre-tRNA synthesis by RNA polymerase III only creates the RNA portion of the adaptor molecule. The corresponding amino acid must be added later, once the tRNA is processed and exported to the cytoplasm. Through the process of tRNA “charging,” each tRNA molecule is linked to its correct amino acid by a group of enzymes called aminoacyl tRNA synthetases. When an amino acid is covalently linked to a tRNA, the resulting complex is known as an aminoacyl-tRNA. At least one type of aminoacyl tRNA synthetase exists for each of the 21 amino acids; the exact number of aminoacyl tRNA synthetases varies by species. These enzymes first bind and hydrolyze ATP to catalyze the formation of a covalent bond between an amino acid and adenosine monophosphate (AMP); a pyrophosphate molecule is expelled in this reaction. This is called “activating” the amino acid. The same enzyme then catalyzes the attachment of the activated amino acid to the tRNA and the simultaneous release of AMP. After the correct amino acid covalently attached to the tRNA, it is released by the enzyme. The tRNA is said to be charged with its cognate amino acid. (the amino acid specified by its anticodon is a tRNA’s cognate amino acid.)
Key Points
- Ribosomes, macromolecular structures composed of rRNA and polypeptide chains, are formed of two subunits (in bacteria and archaea, 30S and 50S; in eukaryotes, 40S and 60S), that bring together mRNA and tRNAs to catalyze protein synthesis.
- Fully assembled ribosomes have three tRNA binding sites: an A site for incoming aminoacyl-tRNAs, a P site for peptidyl-tRNAs, and an E site where empty tRNAs exit.
- tRNAs (transfer ribonucleic acids), which serve to deliver the appropriate amino acid to the growing peptide chain, consist of a modified RNA chain with the appropriate amino acid covalently attached.
- tRNAs have a loop of unbasepaired nucleotides at one end of the molecule that contains three nucleotides that act as the anticodon that basepairs to the mRNA codon.
- Aminoacyl tRNA synthetases are enzymes that load the individual amino acids onto the tRNAs.
Key Terms
- ribosome : protein/mRNA complexes found in all cells that are involved in the production of proteins by translating messenger RNA


10.7: Physical Development in Late Adulthood - Life Expectancy and Quality of Life
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One way to prepare for the future is to find ways to improve quality of life. Life expectancy (how long you can expect to live) in 1900 was about 47 years. In 2017, life expectancy for all races was 77.9, 77.3 for males and 82 for females ( Living Longer: Historical and Projected Life Expectancy in the United States, 1960 to 2060 , U.S. Census Bureau, 2020). For whites, life expectancy was 77.7 for males and 82.82 for females.  Historic racism or years of living under oppressive prejudice and discrimination can increase the incidence of stress-related illness and contribute to a lower life expectancy. As of 2015, the United States ranks 40th among other countries for its life expectancy. Based on data provided by the U.S. Census Bureau in 2020, Japanese and the Swedish men have the longest life expectancies (U.S. Census Bureau, 2020).
Increased life expectancy brings concern over the health and independence of those living longer. Greater attention is now being given to the number of years a person can expect to live without disability which is referred to as active life expectancy. When this distinction is made, we see that although women live longer than men, they are more at risk of living with disability (Weitz, 2007). What factors contribute to poorer health? Marriage has been linked to longevity, but spending years in a stressful marriage can increase the risk of illness. This negative effect is experienced more by women than men and seems accumulates through the years. Its impact on health may not occur until a woman reaches 70 or older (Umberson, Williams, et. al., 2006). Sexism can also create chronic stress. The stress experienced by women as they work outside the home as well as care for family members can also ultimately have a negative impact on health. Poorer health in women is further attributed to an increase in rates of smoking by women in recent years (He et als, 2005).
The shorter life expectancy for men in general, is attributed to greater stress, poorer attention to health, more involvement in dangerous occupations, and higher rates of death due to accidents, homicide, and suicide. Social support can increase longevity. For men, life expectancy and health seems to improve with marriage. Spouses are less likely to engage in risky health practices and wives are more likely to monitor their husband’s diet and health regimes. But men who live in stressful marriages can also experience poorer health as a result.
Key players in improving the quality of life among older adults will be those adults. By exercising, reducing stress, stopping smoking, limiting use of alcohol, and consuming more fruits and vegetables, older adults can expect to live longer and more active lives. (He et. als, 2005). Stress reduction both in late adulthood and earlier in life is also crucial. The reduction of societal stressors can promote active life expectancy. In the last 40 years, smoking rates have decreased, but obesity has increased, and physical activity has only modestly increased.
Attitudes about Aging
Stereotypes about people of in late adulthood lead many to assume that aging automatically brings poor health and mental decline. These stereotypes are reflected in everyday conversations, the media and even in greeting cards (Overstreet, 2006). The following examples serve to illustrate.
1) Grandpa, fishing pole in one hand, pipe in the other, sits on the ground and completes a story being told to his grandson with “. . . and that, Jimmy, is the tale of my very first colonoscopy.” The message inside the card reads, “Welcome to the gross personal story years.” (Shoebox, A Division of Hallmark Cards.)
2) An older woman in a barber shop cuts the hair of an older, dozing man. “So, what do you say today, Earl?” she asks. The inside message reads, “Welcome to the age where pretty much anyplace is a good place for a nap.” (Shoebox, A Division of Hallmark Cards.)
3) A crotchety old man with wire glasses, a crumpled hat, and a bow tie grimaces and the card reads, “Another year older? You’re at the age where you should start eatin’ right, exercisin’, and takin’ vitamins . . .” The inside reads, “Of course you’re also at the age where you can ignore advice by actin like you can’t hear it.” (Hallmark Cards, Inc.)
Of course, these cards are made because they are popular. Age is not revered in the United States, and so laughing about getting older is one way to get relief. The attitudes are examples of ageism, prejudice based on age. Stereotypes such as these can lead to a self-fulfilling prophecy in which beliefs about one’s ability results in actions that make it come true. A positive, optimistic outlook about aging and the impact one can have on improving health is essential to health and longevity. Removing societal stereotypes about aging and helping older adults reject those notions of aging is another way to promote health and active life expectancy among the old.


21: Managing Safety and Health
“We must never forget that the highest appreciation is not to utter words, but to live by them." – Former U.S. President John F. Kennedy
Overview
Anyone who has ever been under the management or supervision of someone who did not care about the individual, did not care about getting the job done right(effectiveness), or did not care about doing the right thing(compliance), would if given the choice, work for someone else. We instinctively know that care and concern is central to thriving. We see how the effects of a lack of concern for the well being of others show up in all walks of life. When communities are neglected there is poverty, crime, stunted growth, and hopelessness. When workplaces are neglected there are inefficient and ineffective work processes, unsafe and unsanitary working conditions, no motivation, accidents and injuries.
And yet we sometimes also believe that if we manage better, control better we can make things better. Managing Safety and Health is definitely about effective management and control of workplace safety. However, if there is no credibility, integrity, no care and concern in the management approach, if workers do not “see” evidence that worker safety and health is a priority, those same workers will be less likely to make safety a priority as well. They won’t see their value as workers or see themselves as the most important stakeholder in worker safety and workplace safety.
Managing safety and health is about setting and establishing the correct tone. In this chapter, eight core elements will demonstrate how “care and concern” is essential to driving compliance with safety and health standards and programs.
Chapter Objective:
- Discuss seven guiding principles for managing safety and health.
- Discuss current workplace safety issues and concerns requiring effective safety leadership.
Learning Outcome:
- Apply practices for effective safety leadership.
Standards: Top most frequently cited standards
Key Terms:
Credibility, integrity, leadership, management, mitigate, plan, principled, stewardship, strategy
Mini-Lecture: Safety Leadership
Topic Required Time: 2 hrs; Independent Study and reflection 1 3/4 hour.
Thumbnail: Foundations of Safety Leadership, www.cpwr.com free to use


4.3: Book | UNESCO Basic Guide to Open Educational Resources (OER)
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This Guide comprises three sections. The first – a summary of the key issues – is presented in the form of a set of ‘Frequently Asked Questions’. Its purpose is to provide readers with a quick and user-friendly introduction to Open Educational Resources (OER) and some of the key issues to think about when exploring how to use OER most effectively. The second section is a more comprehensive analysis of these issues, presented in the form of a traditional research paper. For those who have a deeper interest in OER, this section will assist with making the case for OER more substantively. The third section is a set of appendices, containing more detailed information about specific areas of relevance to OER. These are aimed at people who are looking for substantive information regarding a specific area of interest. Year published: 2011 https://en.unesco.org/icted/content/basic-guide-open-educational-resources-oer |
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Other UNESCO resources, including Creative Commons works and OERs can be found through UNESDOC Digital Library. |


1.2: What Is Psychology?
Learning Objectives
- Define psychology
- Understand the merits of an education in psychology
In Greek mythology, Psyche was a mortal woman whose beauty was so great that it rivaled that of the goddess Aphrodite. Aphrodite became so jealous of Psyche that she sent her son, Eros, to make Psyche fall in love with the ugliest man in the world. However, Eros accidentally pricked himself with the tip of his arrow and fell madly in love with Psyche himself. He took Psyche to his palace and showered her with gifts, yet she could never see his face. While visiting Psyche, her sisters roused suspicion in Psyche about her mysterious lover, and eventually, Psyche betrayed Eros’ wishes to remain unseen to her (Figure \(\PageIndex{1}\)). Because of this betrayal, Eros abandoned Psyche. When Psyche appealed to Aphrodite to reunite her with Eros, Aphrodite gave her a series of impossible tasks to complete. Psyche managed to complete all of these trials; ultimately, her perseverance paid off as she was reunited with Eros and was ultimately transformed into a goddess herself (Ashliman, 2001; Greek Myths & Greek Mythology, 2014).
Psyche comes to represent the human soul’s triumph over the misfortunes of life in the pursuit of true happiness (Bulfinch, 1855); in fact, the Greek word psyche means soul, and it is often represented as a butterfly. The word psychology was coined at a time when the concepts of soul and mind were not as clearly distinguished (Green, 2001). The root ology denotes scientific study of, and psychology refers to the scientific study of the mind. Since science studies only observable phenomena and the mind is not directly observable, we expand this definition to the scientific study of mind and behavior.
The scientific study of any aspect of the world uses the scientific method to acquire knowledge. To apply the scientific method, a researcher with a question about how or why something happens will propose a tentative explanation, called a hypothesis, to explain the phenomenon. A hypothesis is not just any explanation; it should fit into the context of a scientific theory. A scientific theory is a broad explanation or group of explanations for some aspect of the natural world that is consistently supported by evidence over time. A theory is the best understanding that we have of that part of the natural world. Armed with the hypothesis, the researcher then makes observations or, better still, carries out an experiment to test the validity of the hypothesis. That test and its results are then published so that others can check the results or build on them. It is necessary that any explanation in science be testable, which means that the phenomenon must be perceivable and measurable. For example, that a bird sings because it is happy is not a testable hypothesis, since we have no way to measure the happiness of a bird. We must ask a different question, perhaps about the brain state of the bird, since this can be measured. In general, science deals only with matter and energy, that is, those things that can be measured, and it cannot arrive at knowledge about values and morality. This is one reason why our scientific understanding of the mind is so limited, since thoughts, at least as we experience them, are neither matter nor energy. The scientific method is also a form of empiricism. An empirical method for acquiring knowledge is one based on observation, including experimentation, rather than a method based only on forms of logical argument or previous authorities.
It was not until the late 1800s that psychology became accepted as its own academic discipline. Before this time, the workings of the mind were considered under the auspices of philosophy. Given that any behavior is, at its roots, biological, some areas of psychology take on aspects of a natural science like biology. No biological organism exists in isolation, and our behavior is influenced by our interactions with others. Therefore, psychology is also a social science.
Merits of an education in Psychology
Often, students take their first psychology course because they are interested in helping others and want to learn more about themselves and why they act the way they do. Sometimes, students take a psychology course because it either satisfies a general education requirement or is required for a program of study such as nursing or pre-med. Many of these students develop such an interest in the area that they go on to declare psychology as their major. As a result, psychology is one of the most popular majors on college campuses across the United States (Johnson & Lubin, 2011). A number of well-known individuals were psychology majors. Just a few famous names on this list are Facebook’s creator Mark Zuckerberg, television personality and political satirist Jon Stewart, actress Natalie Portman, and filmmaker Wes Craven (Halonen, 2011). About \(6\) percent of all bachelor degrees granted in the United States are in the discipline of psychology (U.S. Department of Education, 2013).
An education in psychology is valuable for a number of reasons. Psychology students hone critical thinking skills and are trained in the use of the scientific method. Critical thinking is the active application of a set of skills to information for the understanding and evaluation of that information. The evaluation of information—assessing its reliability and usefulness— is an important skill in a world full of competing “facts,” many of which are designed to be misleading. For example, critical thinking involves maintaining an attitude of skepticism, recognizing internal biases, making use of logical thinking, asking appropriate questions, and making observations. Psychology students also can develop better communication skills during the course of their undergraduate coursework (American Psychological Association, 2011). Together, these factors increase students’ scientific literacy and prepare students to critically evaluate the various sources of information they encounter.
In addition to these broad-based skills, psychology students come to understand the complex factors that shape one’s behavior. They appreciate the interaction of our biology, our environment, and our experiences in determining who we are and how we will behave. They learn about basic principles that guide how we think and behave, and they come to recognize the tremendous diversity that exists across individuals and across cultural boundaries (American Psychological Association, 2011).
Summary
Psychology derives from the roots psyche (meaning soul) and –ology (meaning scientific study of). Thus, psychology is defined as the scientific study of mind and behavior. Students of psychology develop critical thinking skills, become familiar with the scientific method, and recognize the complexity of behavior.
Glossary
- empirical method
- method for acquiring knowledge based on observation, including experimentation, rather than a method based only on forms of logical argument or previous authorities
- ology
- suffix that denotes “scientific study of”
- psyche
- Greek word for soul
- psychology
- scientific study of the mind and behavior
Contributors and Attributions
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7.6: Problems with hash tables
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Although hash table lookups use constant time on average, the time spent can be significant. Evaluating a good hash function can be a slow operation. In particular, if simple array indexing can be used instead, this is usually faster.
Hash tables in general exhibit poor locality of reference—that is, the data to be accessed is distributed seemingly at random in memory. Because hash tables cause access patterns that jump around, this can trigger microprocessor cache misses that cause long delays. Compact data structures such as arrays, searched with linear search, may be faster if the table is relatively small and keys are cheap to compare, such as with simple integer keys. According to Moore's Law, cache sizes are growing exponentially and so what is considered "small" may be increasing. The optimal performance point varies from system to system; for example, a trial on Parrot shows that its hash tables outperform linear search in all but the most trivial cases (one to three entries).
More significantly, hash tables are more difficult and error-prone to write and use. Hash tables require the design of an effective hash function for each key type, which in many situations is more difficult and time-consuming to design and debug than the mere comparison function required for a self-balancing binary search tree. In open-addressed hash tables it's even easier to create a poor hash function.
Additionally, in some applications, a black hat with knowledge of the hash function may be able to supply information to a hash which creates worst-case behavior by causing excessive collisions, resulting in very poor performance (i.e., a denial of service attack). In critical applications, either universal hashing can be used or a data structure with better worst-case guarantees may be preferable. For details, see Crosby and Wallach's Denial of Service via Algorithmic Complexity Attacks .