14.1: Discovering Antimicrobial Drugs
- Compare and contrast natural, semisynthetic, and synthetic antimicrobial drugs
- Describe the chemotherapeutic approaches of ancient societies
- Describe the historically important individuals and events that led to the development of antimicrobial drugs
Marisa, a 52-year-old woman, was suffering from severe abdominal pain, swollen lymph nodes, fatigue, and a fever. She had just returned home from visiting extended family in her native country of Cambodia. While abroad, she received medical care in neighboring Vietnam for a compressed spinal cord. She still had discomfort when leaving Cambodia, but the pain increased as her trip home continued and her husband drove her straight from the airport to the emergency room.
Her doctor considers whether Marisa could be suffering from appendicitis, a urinary tract infection (UTI), or pelvic inflammatory disease (PID). However, each of those conditions is typically preceded or accompanied by additional symptoms. He considers the treatment she received in Vietnam for her compressed spinal cord, but abdominal pain is not usually associated with spinal cord compression. He examines her health history further.
- What type of infection or other condition may be responsible?
- What type of lab tests might the doctor order?
Most people associate the term chemotherapy with treatments for cancer. However, chemotherapy is actually a broader term that refers to any use of chemicals or drugs to treat disease. Chemotherapy may involve drugs that target cancerous cells or tissues, or it may involve antimicrobial drugs that target infectious microorganisms. Antimicrobial drugs typically work by destroying or interfering with microbial structures and enzymes, either killing microbial cells or inhibiting of their growth. But before we examine how these drugs work, we will briefly explore the history of humans’ use of antimicrobials for the purpose of chemotherapy.
Use of Antimicrobials in Ancient Societies
Although the discovery of antimicrobials and their subsequent widespread use is commonly associated with modern medicine, there is evidence that humans have been exposed to antimicrobial compounds for millennia. Chemical analyses of the skeletal remains of people from Nubia 1 (now found in present-day Sudan) dating from between 350 and 550 AD have shown residue of the antimicrobial agent tetracycline in high enough quantities to suggest the purposeful fermentation of tetracycline-producing Streptomyces during the beer-making process. The resulting beer, which was thick and gruel-like, was used to treat a variety of ailments in both adults and children, including gum disease and wounds. The antimicrobial properties of certain plants may also have been recognized by various cultures around the world, including Indian and Chinese herbalists (Figure \(\PageIndex{1}\)) who have long used plants for a wide variety of medical purposes. Healers of many cultures understood the antimicrobial properties of fungi and their use of moldy bread or other mold-containing products to treat wounds has been well documented for centuries. 2 Today, while about 80% of the world’s population still relies on plant-derived medicines, 3 scientists are now discovering the active compounds conferring the medicinal benefits contained in many of these traditionally used plants.
Give examples of how antimicrobials were used in ancient societies
The First Antimicrobial Drugs
Societies relied on traditional medicine for thousands of years; however, the first half of the 20th century brought an era of strategic drug discovery. In the early 1900s, the German physician and scientist Paul Ehrlich (1854–1915) set out to discover or synthesize chemical compounds capable of killing infectious microbes without harming the patient. In 1909, after screening more than 600 arsenic-containing compounds, Ehrlich’s assistant Sahachiro Hata (1873–1938) found one such “magic bullet.” Compound 606 targeted the bacterium Treponema pallidum , the causative agent of syphilis. Compound 606 was found to successfully cure syphilis in rabbits and soon after was marketed under the name Salvarsan as a remedy for the disease in humans (Figure \(\PageIndex{2}\)). Ehrlich’s innovative approach of systematically screening a wide variety of compounds remains a common strategy for the discovery of new antimicrobial agents even today.
A few decades later, German scientists Josef Klarer, Fritz Mietzsch, and Gerhard Domagk discovered the antibacterial activity of a synthetic dye, prontosil, that could treat streptococcal and staphylococcal infections in mice. Domagk’s own daughter was one of the first human recipients of the drug, which completely cured her of a severe streptococcal infection that had resulted from a poke with an embroidery needle. Gerhard Domagk (1895–1964) was awarded the Nobel Prize in Medicine in 1939 for his work with prontosil and sulfanilamide, the active breakdown product of prontosil in the body. Sulfanilamide, the first synthetic antimicrobial created, served as the foundation for the chemical development of a family of sulfa drugs. A synthetic antimicrobial is a drug that is developed from a chemical not found in nature. The success of the sulfa drugs led to the discovery and production of additional important classes of synthetic antimicrobials, including the quinolines and oxazolidinones.
A few years before the discovery of prontosil, scientist Alexander Fleming (1881–1955) made his own accidental discovery that turned out to be monumental. In 1928, Fleming returned from holiday and examined some old plates of staphylococci in his research laboratory at St. Mary’s Hospital in London. He observed that contaminating mold growth (subsequently identified as a strain of Penicillium notatum ) inhibited staphylococcal growth on one plate. Fleming, therefore, is credited with the discovery of penicillin, the first natural antibiotic, (Figure \(\PageIndex{3}\)). Further experimentation showed that penicillin from the mold was antibacterial against streptococci, meningococci, and Corynebacterium diphtheriae , the causative agent of diphtheria.
Fleming and his colleagues were credited with discovering and identifying penicillin, but its isolation and mass production were accomplished by a team of researchers at Oxford University under the direction of Howard Florey(1898–1968) and Ernst Chain (1906–1979) (Figure \(\PageIndex{3}\)). In 1940, the research team purified penicillin and reported its success as an antimicrobial agent against streptococcal infections in mice. Their subsequent work with human subjects also showed penicillin to be very effective. Because of their important work, Fleming, Florey, and Chain were awarded the Nobel Prize in Physiology and Medicine in 1945.
In the early 1940s, scientist Dorothy Hodgkin (1910–1994), who studied crystallography at Oxford University, used X-rays to analyze the structure of a variety of natural products. In 1946, she determined the structure of penicillin, for which she was awarded the Nobel Prize in Chemistry in 1964. Once the structure was understood, scientists could modify it to produce a variety of semisynthetic penicillins. A semisynthetic antimicrobial is a chemically modified derivative of a natural antibiotic. The chemical modifications are generally designed to increase the range of bacteria targeted, increase stability, decrease toxicity, or confer other properties beneficial for treating infections.
Penicillin is only one example of a natural antibiotic. Also in the 1940s, Selman Waksman (1888–1973) (Figure \(\PageIndex{4}\)), a prominent soil microbiologist at Rutgers University, led a research team that discovered several antimicrobials, including actinomycin, streptomycin, and neomycin. The discoveries of these antimicrobials stemmed from Waksman’s study of fungi and the Actinobacteria, including soil bacteria in the genus Streptomyces , known for their natural production of a wide variety of antimicrobials. His work earned him the Nobel Prize in Physiology and Medicine in 1952. The actinomycetes are the source of more than half of all natural antibiotics 4 and continue to serve as an excellent reservoir for the discovery of novel antimicrobial agents. Some researchers argue that we have not yet come close to tapping the full antimicrobial potential of this group. 5
Why is the soil a reservoir for antimicrobial resistance genes?
Key Concepts and Summary
- Antimicrobial drugs produced by purposeful fermentation and/or contained in plants have been used as traditional medicines in many cultures for millennia.
- The purposeful and systematic search for a chemical “magic bullet” that specifically target infectious microbes was initiated by Paul Ehrlich in the early 20th century.
- The discovery of the natural antibiotic , penicillin, by Alexander Fleming in 1928 started the modern age of antimicrobial discovery and research.
- Sulfanilamide, the first synthetic antimicrobial , was discovered by Gerhard Domagk and colleagues and is a breakdown product of the synthetic dye, prontosil.
Footnotes
- 1 M.L. Nelson et al. “Brief Communication: Mass Spectroscopic Characterization of Tetracycline in the Skeletal Remains of an Ancient Population from Sudanese Nubia 350–550 CE.” American Journal of Physical Anthropology 143 no. 1 (2010):151–154.
- 2 M. Wainwright. “Moulds in Ancient and More Recent Medicine.” Mycologist 3 no. 1 (1989):21–23.
- 3 S. Verma, S.P. Singh. “Current and Future Status of Herbal Medicines.” Veterinary World 1 no. 11 (2008):347–350.
- 4 J. Berdy. “Bioactive Microbial Metabolites.” The Journal of Antibiotics 58 no. 1 (2005):1–26.
- 5 M. Baltz. “Antimicrobials from Actinomycetes: Back to the Future.” Microbe 2 no. 3 (2007):125–131.


11.16: The Birth of Stars and the Discovery of Planets outside the Solar System (Exercises)
For Further Exploration
Articles
Star Formation
Blaes, O. “A Universe of Disks.” Scientific American (October 2004): 48. On accretion disks and jets around young stars and black holes.
Croswell, K. “The Dust Belt Next Door [Tau Ceti].” Scientific American (January 2015): 24. Short intro to recent observations of planets and a wide dust belt.
Frank, A. “Starmaker: The New Story of Stellar Birth.” Astronomy (July 1996): 52.
Jayawardhana, R. “Spying on Stellar Nurseries.” Astronomy (November 1998): 62. On protoplanetary disks.
O’Dell, C. R. “Exploring the Orion Nebula.” Sky & Telescope (December 1994): 20. Good review with Hubble results.
Ray, T. “Fountains of Youth: Early Days in the Life of a Star.” Scientific American (August 2000): 42. On outflows from young stars.
Young, E. “Cloudy with a Chance of Stars.” Scientific American (February 2010): 34. On how clouds of interstellar matter turn into star systems.
Young, Monica “Making Massive Stars.” Sky & Telescope (October 2015): 24. Models and observations on how the most massive stars form.
Websites
Formation of Stars: https://www.spacetelescope.org/scien...tion_of_stars/ . Star Formation page from the Hubble Space Telescope, with links to images and information.
Videos
A Star Is Born: www.discovery.com/tv-shows/ot...-star-is-born/. Discovery Channel video with astronomer Michelle Thaller (2:25).
Review Questions
- Give several reasons the Orion molecular cloud is such a useful “laboratory” for studying the stages of star formation.
- Why is star formation more likely to occur in cold molecular clouds than in regions where the temperature of the interstellar medium is several hundred thousand degrees?
- Why have we learned a lot about star formation since the invention of detectors sensitive to infrared radiation?
- Describe what happens when a star forms. Begin with a dense core of material in a molecular cloud and trace the evolution up to the time the newly formed star reaches the main sequence.
- Describe how the T Tauri star stage in the life of a low-mass star can lead to the formation of a Herbig-Haro (H-H) object.
- Look at the four stages shown in Figure \(21.1.7\) in Section 21.1. In which stage(s) can we see the star in visible light? In infrared radiation?
- The evolutionary track for a star of 1 solar mass remains nearly vertical in the H–R diagram for a while (see Figure \(21.2.1\) in Section 21.2). How is its luminosity changing during this time? Its temperature? Its radius?
- Two protostars, one 10 times the mass of the Sun and one half the mass of the Sun are born at the same time in a molecular cloud. Which one will be first to reach the main sequence stage, where it is stable and getting energy from fusion?

Thought Questions
- A friend of yours who did not do well in her astronomy class tells you that she believes all stars are old and none could possibly be born today. What arguments would you use to persuade her that stars are being born somewhere in the Galaxy during your lifetime?
- Observations suggest that it takes more than 3 million years for the dust to begin clearing out of the inner regions of the disks surrounding protostars. Suppose this is the minimum time required to form a planet. Would you expect to find a planet around a 10-\(M_{\text{Sun}}\) star? (Refer to Figure \(21.2.1\) in Section 21.2.)


5.1: The Damped Harmonic Oscillator
Consider a particle of mass \(m\) subject to a spring force and a damping force. The particle can move along one dimension, with \(x(t)\) denoting its displacement at time \(t\) . The damping coefficient is \(2m \gamma\) , and the spring constant is \(k = m\omega_0^2\) . The parameters \(m\) , \(\gamma\) , and \(\omega_0\) are all positive real numbers.
The motion of the particle can be derived using Newton’s second law: \[m \frac{d^2 x}{dt^2} = F(x,t) = - 2m\gamma \frac{dx}{dt} - m\omega_0^2 x(t).\] Dividing by the common factor of \(m\) , and bringing everything to one side, gives \[\frac{d^2 x}{dt^2} + 2\gamma \frac{dx}{dt} + \omega_0^2 x(t) = 0.\] This is called the damped harmonic oscillator equation .
Note
Sometimes, we write the damped harmonic oscillator equation as: \[\left[\frac{d^2}{dt^2} + 2\gamma \frac{d}{dt} + \omega_0^2 \right]\, x(t) = 0.\] The quantity in square brackets is a linear differential operator acting on \(x(t)\) . The three terms in the operator correspond to the three “ingredients” of the damped harmonic oscillator model: (i) a second derivative term stemming from Newton’s second law, (ii) a first derivative term representing the effects of damping, and (iii) a constant term representing the oscillation induced by the spring force.
Writing the equation this way helps emphasize that it is linear: i.e., any superposition of solutions is likewise a solution (see Section 5.2).
Behavior of the solution
The damped harmonic oscillator equation is a second-order ordinary differential equation (ODE). Its general solution must contain two free parameters, which are usually (but not necessarily) specified by the initial displacement \(x(0)\) and initial velocity \(\dot{x}(0)\) .
For \(\gamma = 0\) (zero damping), the system reduces to the simple harmonic oscillator . From previous physics courses, we know that the general solution to the simple harmonic oscillator has the form \[x(t) = A \cos(\omega_0 t + \phi), \label{simple-gensol}\] where \(A\) and \(\phi\) are free parameters. This describes a sinusoidal motion with constant amplitude \(A\) , phase \(\phi\) , and frequency \(\omega_0\) .
By the way, some authors call \(\omega_0\) an “angular frequency”, reserving the term “frequency” for the quantity \(f_0 = \omega_0/2\pi\) . But we will always deal with \(\omega_0\) rather than \(f_0\) . As such, we can refer to \(\omega_0\) as “frequency” for brevity, without risk of ambiguity.
The quantity \(\omega_0\) is directly related to the spring constant by \(k = m\omega_0^2\) ; in fact, this is precisely why we parameterized the spring constant in this way. It is called the natural frequency — i.e., the natural oscillation frequency of the system when damping is absent.
Eq. \(\eqref{simple-gensol}\) can be re-expressed in terms of the initial displacement \(x(0) = x_0\) and initial velocity \(\dot{x}(0) = v_0\) . It is straightforward to show that \[A = \sqrt{x_0^2 + \left(\frac{v_0}{\omega_0}\right)^2}, \quad \phi = -\tan^{-1}\left(\frac{v_0}{\omega_0 x_0}\right).\]
Now consider \(\gamma > 0\) . A damping force now opposes the motion, doing work against the particle and causing it to lose energy over time. Hence, the particle can no longer oscillate forever around the equilibrium position. If the damping force is relatively weak, the energy lost per cycle is relatively small, so the motion of the particle should consist of an oscillation whose amplitude diminishes slowly over time. For \(t \rightarrow \infty\) , both \(x\) and \(\dot{x}\) go to zero.


8.3: Cardiovascular Assessment
A thorough assessment of the heart provides valuable information about the function of a patient’s cardiovascular system. Understanding how to properly assess the cardiovascular system and identifying both normal and abnormal assessment findings will allow the nurse to provide quality, safe care to the patient.
Before assessing a patient’s cardiovascular system, it is important to understand the various functions of the cardiovascular system. In addition to the information provided in the “Review of Cardiac Basics” section, the following images provide an overview of the cardiovascular system. Figure 8.1 [1] provides an overview of the structure of the heart. Note the main cardiac structures are the atria, ventricles, and heart valves. Figure 8.2 [2] demonstrates blood flow through the heart. Notice the flow of deoxygenated blood from the posterior and superior vena cava into the right atria and ventricle during diastole (indicated by blue coloring of these structures). The right ventricle then pumps deoxygenated blood to the lungs via the pulmonary artery during systole. At the same time, oxygenated blood from the lungs returns to the left atria and ventricle via the pulmonary veins during diastole (indicated by red coloring of these structures) and then is pumped out to the body via the aorta during systole. Figure \(\PageIndex{1}\) [3] demonstrates the conduction system of the heart. This image depicts the conduction pathway through the heart as the tissue responds to electrical stimulation. Figure \(\PageIndex{2}\) [4] illustrates the arteries of the circulatory system, and Figure \(\PageIndex{3}\) [5] depicts the veins of the circulatory system. The purpose of these figures is to facilitate understanding of the electrical and mechanical function of the heart within the cardiovascular system.
Assessing the cardiovascular system includes performing several subjective and objective assessments. At times, assessment findings are modified according to life span considerations.
Subjective Assessment
The subjective assessment of the cardiovascular and peripheral vascular system is vital for uncovering signs of potential dysfunction. To complete the subjective cardiovascular assessment, the nurse begins with a focused interview. The focused interview explores past medical and family history, medications, cardiac risk factors, and reported symptoms. Symptoms related to the cardiovascular system include chest pain, peripheral edema, unexplained sudden weight gain, shortness of breath (dyspnea), irregular pulse rate or rhythm, dizziness, or poor peripheral circulation. Any new or worsening symptoms should be documented and reported to the health care provider.
| Symptom | Question |
Follow-Up Safety Note: If findings indicate current severe symptoms suggestive of myocardial infarction or another critical condition, suspend the remaining cardiovascular assessment and obtain immediate assistance according to agency policy or call 911. |
|---|---|---|
| Chest Pain | Have you had any pain or pressure in your chest, neck, or arm? |
Review how to assess a patient’s chief complaint using the OLD CART & ICE method in the “Health History” chapter.
|
|
Shortness of Breath
( Dyspnea ) |
Do you ever feel short of breath with activity?
Do you ever feel short of breath while sleeping? Do you feel short of breath when lying flat? |
What level of activity elicits shortness of breath?
How long does it take you to recover?
Have you ever woken up from sleeping feeling suddenly short of breath
How many pillows do you need to sleep, or do you sleep in a chair ( orthopnea )? Has this recently changed? |
| Edema |
Have you noticed swelling of your feet or ankles?
Have you noticed your rings, shoes, or clothing feel tight at the end of the day? Have you noticed any unexplained, sudden weight gain? Have you noticed any new abdominal fullness? |
Has this feeling of swelling or restriction gotten worse?
Is there anything that makes the swelling better (e.g., sitting with your feet elevated)? How much weight have you gained? Over what time period have you gained this weight? |
| Palpitations |
Have you ever noticed your heart feels as if it is racing or “fluttering” in your chest?

When did palpitations start? Have you previously been treated for palpitations? If so, what treatment did you receive? |
|
Dizziness
( Syncope ) |
Do you ever feel light-headed?
Do you ever feel dizzy? Have you ever fainted? |
Can you describe what happened?
Did you have any warning signs? Did this occur with position change? |
| Poor Peripheral Circulation |
Do your hands or feet ever feel cold or look pale or bluish?
Do you have pain in your feet or lower legs when exercising? |
What, if anything, brings on these symptoms?
How much activity is needed to cause this pain? Is there anything, such as rest, that makes the pain better? |
| Calf Pain | Do you currently have any constant pain in your lower legs? | Can you point to the area of pain with one finger? |
| Topic | Questions |
|---|---|
| Medical History |
Have you ever been diagnosed with any heart or circulation conditions, such as high blood pressure, coronary artery disease, peripheral vascular disease, high cholesterol, heart failure, or valve problems?
Have you had any procedures done to improve your heart function, such as ablation or stent placement? Have you ever had a heart attack or stroke? |
| Medications | Do you take any heart-related medications, herbs, or supplements to treat blood pressure, chest pain, high cholesterol, cardiac rhythm, fluid retention, or the prevention of clots? |
| Cardiac Risk Factors |
Have your parents or siblings been diagnosed with any heart conditions?
Do you smoke or vape?
If you do not currently smoke, have you smoked in the past?
Are you physically active during the week?
What does a typical day look like in your diet?
Do you drink alcoholic drinks?
Would you say you experience stress in your life?
How many hours of sleep do you normally get each day?
|
Objective Assessment
The physical examination of the cardiovascular system involves the interpretation of vital signs, inspection, palpation, and auscultation of heart sounds as the nurse evaluates for sufficient perfusion and cardiac output.
Equipment needed for a cardiovascular assessment includes a stethoscope, penlight, centimeter ruler or tape measure, and sphygmomanometer . [10]
Evaluate Vital Signs and Level of Consciousness
Interpret the blood pressure and pulse readings to verify the patient is stable before proceeding with the physical exam. Assess the level of consciousness; the patient should be alert and cooperative.
As a general rule of thumb, findings of systolic blood pressure in adults less than 100,or a pulse rate less than 60 or greater than 100,require immediate follow-up. Keep in mind that excessive drowsiness, restlessness, or irritability can be symptoms of hypoxia.
Inspection
- Skin color to assess perfusion. Inspect the face, lips, and fingertips for cyanosis or pallor. Cyanosis is a bluish discoloration of the skin, lips, and nail beds and indicates decreased perfusion and oxygenation. Pallor is the loss of color, or paleness of the skin or mucous membranes, as a result of reduced blood flow, oxygenation, or decreased number of red blood cells. Patients with light skin tones should be pink in color. For those with darker skin tones, assess for pallor on the palms, conjunctiva, or inner aspect of the lower lip.
- Jugular Vein Distension (JVD) . Inspect the neck for JVD that occurs when the increased pressure of the superior vena cava causes the jugular vein to bulge, making it most visible on the right side of a person’s neck. JVD should not be present in the upright position or when the head of bed is at 30-45 degrees.
- Precordium for abnormalities. Inspect the chest area over the heart (also called precordium ) for deformities, scars, or any abnormal pulsations the underlying cardiac chambers and great vessels may produce.
-
Extremities:
- Upper Extremities: Inspect the fingers, arms, and hands bilaterally noting Color, Warmth, Movement, Sensation (CWMS). Alterations or bilateral inconsistency in CWMS may indicate underlying conditions or injury. Assess capillary refill by compressing the nail bed until it blanches and record the time taken for the color to return to the nail bed. Normal capillary refill is less than 3 seconds. [11]
-
Lower Extremities:
Inspect the toes, feet, and legs bilaterally, noting CWMS, capillary refill, and the presence of peripheral edema, superficial distended veins, and hair distribution. Document the location and size of any skin ulcers.
- Edema: Note any presence of edema. Peripheral edema is swelling that can be caused by infection, thrombosis, or venous insufficiency due to an accumulation of fluid in the tissues. (See Figure \(\PageIndex{6}\) [12] for an image of pedal edema.) [13]
- Deep Vein Thrombosis (DVT) : A deep vein thrombosis (DVT) is a blood clot that forms in a vein deep in the body. DVT requires emergency notification of the health care provider and immediate follow-up because of the risk of developing a life-threatening pulmonary embolism . [14] Inspect the lower extremities bilaterally. Assess for size, color, temperature, and for presence of pain in the calves. Unilateral warmth, redness, tenderness, swelling in the calf, or sudden onset of intense, sharp muscle pain that increases with dorsiflexion of the foot is an indication of a deep vein thrombosis (DVT). [15] See Figure \(\PageIndex{7}\) [16] for an image of a DVT in the patient’s right leg, indicated by unilateral redness and edema.
Auscultation
Heart Sounds
Auscultation is routinely performed over five specific areas of the heart to listen for corresponding valvular sounds. These auscultation sites are often referred to by the mnemonic “APE To Man,” referring to Aortic, Pulmonic, Erb’s point, Tricuspid, and Mitral areas (see Figure \(\PageIndex{8}\) [17] for an illustration of cardiac auscultation areas). The aortic area is the second intercostal space to the right of the sternum. The pulmonary area is the second intercostal space to the left of the sternum. Erb’s point is directly below the aortic area and located at the third intercostal space to the left of the sternum. The tricuspid (or parasternal) area is at the fourth intercostal space to the left of the sternum. The mitral (also called apical or left ventricular area) is the fifth intercostal space at the midclavicular line.
Auscultation usually begins at the aortic area (upper right sternal edge). Use the diaphragm of the stethoscope to carefully identify the S1 and S2 sounds. They will make a “lub-dub” sound. Note that when listening over the area of the aortic and pulmonic valves, the “dub” (S2) will sound louder than the “lub” (S2). Move the stethoscope sequentially to the pulmonic area (upper left sternal edge), Erb’s point (left third intercostal space at the sternal border), and tricuspid area (fourth intercostal space. When assessing the mitral area for female patients, it is often helpful to ask them to lift up their breast tissue so the stethoscope can be placed directly on the chest wall. Repeat this process with the bell of the stethoscope. The apical pulse should be counted over a 60-second period. For an adult, the heart rate should be between 60 and 100 with a regular rhythm to be considered within normal range. The apical pulse is an important assessment to obtain before the administration of many cardiac medications.
The first heart sound (S1) identifies the onset of systole, when the atrioventricular (AV) valves (mitral and tricuspid) close and the ventricles contract and eject the blood out of the heart. The second heart sound (S2) identifies the end of systole and the onset of diastole when the semilunar valves close, the AV valves open, and the ventricles fill with blood. When auscultating, it is important to identify the S1 (“lub”) and S2 (“dub”) sounds, evaluate the rate and rhythm of the heart, and listen for any extra heart sounds.
Listen to a normal S1/S2 sound. It may be helpful to use earbuds or a headphone:
Auscultating Heart Sounds
- To effectively auscultate heart sounds, patient repositioning may be required. Ask the patient to lean forward if able, or position them to lie on their left side.
- It is common to hear lung sounds when auscultating the heart sounds. It may be helpful to ask the patient to briefly hold their breath if lung sounds impede adequate heart auscultation. Limit the holding of breath to 10 seconds or as tolerated by the patient.
- Environmental noise can cause difficulty in auscultating heart sounds. Removing environmental noise by turning down the television volume or shutting the door may be required for an accurate assessment.
- Patients may try to talk to you as you are assessing their heart sounds. It is often helpful to explain the procedure such as, “I am going to take a few minutes to listen carefully to the sounds of blood flow going through your heart. Please try not to speak while I am listening, so I can hear the sounds better.”
Extra Heart Sounds
Extra heart sounds include clicks, murmurs, S3 and S4 sounds, and pleural friction rubs. These extra sounds can be difficult for a novice to distinguish, so if you notice any new or different sounds, consult an advanced practitioner or notify the provider. A midsystolic click , associated with mitral valve prolapse, may be heard with the diaphragm at the apex or left lower sternal border.
A click may be followed by a murmur. A murmur is a blowing or whooshing sound that signifies turbulent blood flow often caused by a valvular defect. New murmurs not previously recorded should be immediately communicated to the health care provider. In the aortic area, listen for possible murmurs of aortic stenosis and aortic regurgitation with the diaphragm of the stethoscope. In the pulmonic area, listen for potential murmurs of pulmonic stenosis and pulmonary and aortic regurgitation. In the tricuspid area, at the fourth and fifth intercostal spaces along the left sternal border, listen for the potential murmurs of tricuspid regurgitation, tricuspid stenosis, or ventricular septal defect.
Listen to a heart murmur caused by mitral valve regurgitation:
S3 and S4 sounds, if present, are often heard best by asking the patient to lie on their left side and listening over the apex with the bell of the stethoscope. An S3 sound, also called a ventricular gallop , occurs with fluid overload or heart failure when the ventricles are filling. It occurs after the S2 and sounds like “lub-dub-dah,” or a sound similar to a horse galloping. The S4 sound, also called atrial gallop , occurs immediately before the S1 and sounds like “ta-lub-dub.” An S4 sound can occur with decreased ventricular compliance or coronary artery disease. [18]
Listen to a S3 ventricular gallop:
Listen to a S4 atrial gallop:
A pleural friction rub is caused by inflammation of the pericardium and sounds like sandpaper being rubbed together. It is best heard at the apex or left lower sternal border with the diaphragm as the patient sits up, leans forward, and holds their breath.
Carotid Sounds
The carotid artery may be auscultated for bruits . Bruits are a swishing sound due to turbulence in the blood vessel and may be heard due to atherosclerotic changes.
Palpation
Palpation is used to evaluate the precordium, peripheral pulses, capillary refill, and for the presence of edema. When palpating these areas, also pay attention to the temperature and moisture of the skin.
Pulses
Compare the rate, rhythm, and quality of arterial pulses bilaterally, including the carotid, brachial, radial, femoral, posterior tibialis, and dorsalis pedis pulses. Bilateral comparison for all pulses (except the carotid) is important for determining subtle variations in pulse strength. Carotid pulses should be palpated on one side at a time to avoid decreasing perfusion of the brain. The posterior tibial artery is located just behind the medial malleolus. It can be palpated by scooping the patient’s heel in your hand and wrapping your fingers around so that the tips come to rest on the appropriate area just below the medial malleolus. The dorsalis pedis artery is located just lateral to the extensor tendon of the big toe and can be identified by asking the patient to flex their toe while you provide resistance to this movement. Gently place the tips of your second, third, and fourth fingers adjacent to the tendon to feel the pulse.
The quality of the pulse is graded on a scale of 0 to 3, with 0 being absent pulses, 1 being decreased pulses, 2 is within normal range, and 3 being increased (also referred to as “bounding”). If unable to palpate a pulse, additional assessment is needed. First, determine if this is a new or chronic finding. Second, if available, use a doppler ultrasound to determine the presence or absence of the pulse. Many agencies use doppler ultrasound to document if a nonpalpable pulse is present. If the pulse is not found, this could be a sign of an emergent condition requiring immediate follow-up and provider notification. See Figures \(\PageIndex{9}\) [19] and \(\PageIndex{10}\) [20] for images of assessing pedal pulses.
Capillary Refill
The capillary refill test is performed on the nail beds to monitor perfusion , the amount of blood flow to tissue. Pressure is applied to a fingernail or toenail until it pales, indicating that the blood has been forced from the tissue under the nail. This paleness is called blanching . Once the tissue has blanched, pressure is removed. Capillary refill time is defined as the time it takes for the color to return after pressure is removed. If there is sufficient blood flow to the area, a pink color should return within 2 to 3 seconds after the pressure is removed. [21]
Edema
Edema occurs when one can visualize visible swelling caused by a buildup of fluid within the tissues. If edema is present on inspection, palpate the area to determine if the edema is pitting or nonpitting. Press on the skin to assess for indentation, ideally over a bony structure, such as the tibia. If no indentation occurs, it is referred to as nonpitting edema. If indentation occurs, it is referred to as pitting edema . See Figure \(\PageIndex{11}\) [22] for images demonstrating pitting edema.
Note the depth of the indention and how long it takes for the skin to rebound back to its original position. The indentation and time required to rebound to the original position are graded on a scale from 1 to 4. Edema rated at 1+ indicates a barely detectable depression with immediate rebound, and 4+ indicates a deep depression with a time lapse of over 20 seconds required to rebound. See Figure \(\PageIndex{12}\) [23] for an illustration of grading edema. Additionally, it is helpful to note edema may be difficult to observe in larger patients. It is also important to monitor for sudden changes in weight, which is considered a probable sign of fluid volume overload.
Heaves or Thrills
You may observe advanced practice nurses and other health care providers palpating the anterior chest wall to detect any abnormal pulsations the underlying cardiac chambers and great vessels may produce. Precordial movements should be evaluated at the apex (mitral area). It is best to examine the precordium with the patient supine because if the patient is turned on the left side, the apical region of the heart is displaced against the lateral chest wall, distorting the chest movements. [24] A heave or lift is a palpable lifting sensation under the sternum and anterior chest wall to the left of the sternum that suggests severe right ventricular hypertrophy. A thrill is a vibration felt on the skin of the precordium or over an area of turbulence, such as an arteriovenous fistula or graft.
Life Span Considerations
The cardiovascular assessment and expected findings should be modified according to common variations across the life span.
Infants and Children
A murmur may be heard in a newborn in the first few days of life until the ductus arteriosus closes.
When assessing the cardiovascular system in children, it is important to assess the apical pulse. Parameters for expected findings vary according to age group. After a child reaches adolescence, a radial pulse may be assessed. Table \(\PageIndex{2}\) outlines the expected apical pulse rate by age.
| Age Group | Heart Rate |
|---|---|
| Preterm | 120-180 |
| Newborn (0 to 1 month) | 100-160 |
| Infant (1 to 12 months) | 80-140 |
| Toddler (1 to 3 years) | 80-130 |
| Preschool (3 to 5 years) | 80-110 |
| School Age (6 to 12 years) | 70-100 |
| Adolescents (13 to 18 years) | 60-90 |
Listen to pediatric heart tones:
Older Adults
In adults over age 65, irregular heart rhythms and extra sounds are more likely. An “irregularly irregular” rhythm suggests atrial fibrillation , and further investigation is required if this is a new finding. See the hyperlink in the box below for more information about atrial fibrillation.
Listen to atrial fibrillation:
For more information on atrial fibrillation, visit the following web page: CDC Atrial Fibrillation .
Expected Versus Unexpected Findings
After completing a cardiovascular assessment, it is important for the nurse to use critical thinking to determine if any findings require follow-up. Depending on the urgency of the findings, follow-up can range from calling the health care provider to calling the rapid response team. Table \(\PageIndex{3}\) compares examples of expected findings, meaning those considered within normal limits, to unexpected findings, which require follow-up. Critical conditions are those that should be reported immediately and may require notification of a rapid response team.
| Assessment | Expected Findings | Unexpected Findings (Document and notify the provider if this is a new finding*) |
|---|---|---|
| Inspection | Apical impulse may or may not be visible |
Scars not previously documented that could indicate prior cardiac surgeries
Heave or lift observed in the precordium Chest anatomy malformations |
| Palpation | Apical pulse felt over midclavicular fifth intercostal space |
Apical pulse felt to the left of the midclavicular fifth intercostal space
Additional movements over precordium such as a heave, lift, or thrill |
| Auscultation | S1 and S2 heart sounds in a regular rhythm |
New irregular heart rhythm
Extra heart sounds such as a murmur, S3, or S4 |
| *CRITICAL CONDITIONS to report immediately |
Symptomatic tachycardia at rest (HR>100 bpm)
Symptomatic bradycardia (HR<60 bpm) New systolic blood pressure (<100 mmHg) Orthostatic blood pressure changes (see “Blood Pressure” chapter for more information) New irregular heart rhythm New extra heart sounds such as a murmur, S3, or S4 New abnormal cardiac rhythm changes Reported chest pain, calf pain, or worsening shortness of breath |
See Table \(\PageIndex{4}\) for a comparison of expected versus unexpected findings when assessing the peripheral vascular system.
| Assessment | Expected Findings | Unexpected Findings (Document or notify provider if new finding*) |
|---|---|---|
| Inspection |
Skin color uniform and appropriate for race bilaterally
Equal hair distribution on upper and lower extremities Absence of jugular vein distention (JVD) Absence of edema Sensation and movement of fingers and toes intact |
Cyanosis or pallor, indicating decreased perfusion
Decreased or unequal hair distribution Presence of jugular vein distention (JVD) in an upright position or when head of bed is 30-45 degrees New or worsening edema Rapid and unexplained weight gain Impaired movement or sensation of fingers and toes |
| Palpation |
Skin warm and dry
Pulses present and equal bilaterally Absence of edema Capillary refill less than 2 seconds |
Skin cool, excessively warm, or diaphoretic
Absent, weak/thready, or bounding pulses New irregular pulse New or worsening edema Capillary refill greater than 2 seconds Unilateral warmth, redness, tenderness, or edema, indicating possible deep vein thrombosis (DVT) |
| Auscultation | Carotid pulse | Carotid bruit |
| *CRITICAL CONDITIONS to report immediately |
Cyanosis
Absent pulse (and not heard using Doppler device) Capillary refill time greater than 3 seconds Unilateral redness, warmth, and edema, indicating a possible deep vein thrombosis (DVT) |
- “Diagram of the human heart” by Wapcaplet is licensed under CC BY-SA 3.0 ↵
- “Diagram of the human heart” by Wapcaplet is licensed under CC BY-SA 3.0 ↵
- “ 2018 Conduction System of Heart.jpg ” by OpenStax is licensed under CC-BY-3.0 . ↵
- “ Arterial System en.svg ” by LadyofHats , Mariana Ruiz Villarreal is in the Public Domain ↵
- “ Venous system en.svg ” by Lady of Hats Mariana Ruiz Vilarreal is in the Public Domain ↵
- This work is a derivative of Clinical Procedures for Safer Patient Care by British Columbia Institute of Technology licensed under CC BY 4.0 ↵
- Felner, J. M. (1990). An overview of the cardiovascular system. In Walker, H. K., Hall, W. D., & Hurst, J. W. (Eds.), Clinical methods: The history, physical, and laboratory examinations (3rd ed., Chapter 7). Butterworths. www.ncbi.nlm.nih.gov/books/NBK393/↵
- Scott, C. & MacInnes, J. D. (2013, September 27). Cardiac patient assessment: putting the patient first. British Journal of Nursing, 15 (9). doi.org/10.12968/bjon.2<IP_ADDRESS>91↵
- Scott, C. & MacInnes, J. D. (2013, September 27). Cardiac patient assessment: putting the patient first. British Journal of Nursing, 15 (9). doi.org/10.12968/bjon.2<IP_ADDRESS>91↵
- Felner, J. M. (1990). An overview of the cardiovascular system. In Walker, H. K., Hall, W. D., & Hurst, J. W. (Eds.), Clinical methods: The history, physical, and laboratory examinations (3rd ed., Chapter 7). Butterworths. www.ncbi.nlm.nih.gov/books/NBK393/↵
- This work is a derivative of Clinical Procedures for Safer Patient Care by British Columbia Institute of Technology licensed under CC BY 4.0 ↵
- “ Swollen feet at Harefield Hospital edema.jpg” by Ryaninuk is licensed under CC BY-SA 4.0 ↵
- Simon, E. C. (2014). Leg edema assessment and management. MEDSURG Nursing, 23(1), 44-53. ↵
- This work is a derivative of Clinical Procedures for Safer Patient Care by British Columbia Institute of Technology licensed under CC BY 4.0 ↵
- This work is a derivative of Clinical Procedures for Safer Patient Care by British Columbia Institute of Technology licensed under CC BY 4.0 ↵
- “ Deep vein thrombosis of the right leg.jpg ” by James Heilman, MD is licensed under CC BY-SA 3.0 ↵
- “Cardiac Auscultation Areas” by Meredith Pomietlo for Chippewa Valley Technical College is licensed under CC BY 4.0 ↵
- Felner, J. M. (1990). An overview of the cardiovascular system. In Walker, H. K., Hall, W. D., & Hurst, J. W. (Eds.), Clinical methods: The history, physical, and laboratory examinations (3rd ed., Chapter 7). Butterworths. www.ncbi.nlm.nih.gov/books/NBK393/↵
- “DSC_2277.jpg” by British Columbia Institute of Technology is licensed under CC BY 4.0 . Access for free at https://opentextbc.ca/clinicalskills/chapter/2-5-focussed-respiratory-assessment/ ↵
- “DSC_2314.jpg” by British Columbia Institute of Technology is licensed under CC BY 4.0. Access for free at https://opentextbc.ca/clinicalskills/chapter/2-5-focussed-respiratory-assessment/ ↵
- A.D.A.M. Medical Encyclopedia [Internet]. Atlanta (GA): A.D.A.M., Inc.; c1997-2020. Capillary nail refill test; [updated 2020, Aug 9] https://medlineplus.gov/ency/article/003247.htm ↵
- “ Combinpedal.jpg ” by James Heilman, MD is licensed under CC BY-SA 3.0 ↵
- “Grading of Edema” by Meredith Pomietlo for Chippewa Valley Technical College is licensed under CC BY 4.0 ↵
- Felner, J. M. (1990). An overview of the cardiovascular system. In Walker, H. K., Hall, W. D., & Hurst, J. W. (Eds.), Clinical methods: The history, physical, and laboratory examinations (3rd ed., Chapter 7). Butterworths. www.ncbi.nlm.nih.gov/books/NBK393/↵


1.11: Words of Wisdom- These Are the Best Years of Your Life
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  College provides an amazing opportunity to expand your mind, meet unique people you can deeply connect with, and discover new aspects of yourself. Being aware of this energy and taking full advantage of these opportunities can be life changing.
You learn a lot about yourself when living on your own for the first time or studying topics that are completely taboo at your home’s kitchen table. When I transferred to a four-year institution, I found the strength to come out. Realizing I was gay led me to question where I belonged in the religion I was raised in and an enlightening journey ensued of exploring Buddhism, Native American beliefs, and even New Age mysticism. This process of questioning what I believed helped me to create a spiritual foundation that makes sense to me. I kept the best of what I was raised in and upgraded the rest!
I also discovered that the college I attended had amazing tools to help me be as healthy as possible. I used the free gym and knew the counseling center was there if anything became too tough. I also chose incredible electives (including Mountaineering and Modern Dance) that stretched my physical capabilities. Additionally, I made deep connections with my professors, many of whom remain friends. These smart, caring people validated my journey and were my safety net as I grew out of my old, comfortable self.
Another incredible lesson learned was the importance of balance. I couldn’t party every night and neglect my schoolwork without consequences. I figured out the hard way that I really did need sleep and I couldn’t nourish my body on coffee and pizza alone. In a moment of brilliance, I also figured out that if I used time with my friends as a reward for finishing my work, I would study and complete assignments more efficiently. Fun can be a great motivator—try this; it works!
In college, the emphasis is often on the mind.  Leave college brighter, healthier, and with a new understanding of yourself. Try that yoga or nutrition class. Join that new club. Trade in that soda for water. Jump into that drum circle or improvisation group. Who knows what you will discover—it just may be greatness!
CC licensed content, Shared previously:
Foundations of Academic Success: Words of Wisdom. Edited by Thomas Priester. Essay authored by Sara Vacin. Located at: https://milnepublishing.geneseo.edu/...-of-your-life/ License: CC BY: Attribution.


6.3: Homework- Numeric Integration Techniques
-
Given the picture of \(f(x)\), find the following definite integrals.
-
\(\int_{-2}^2 f(x)dx\).
\(2\)ans
-
\(\int_{2}^7 f(x)dx\).
\(8\)ans
-
\(\int_0^6 f(x)dx\).
\(8\)ans
-
\(\int_4^7 f(x)dx\).
\(0\)ans
-
\(\int_{-2}^7 f(x)dx\).
\(10\)ans
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\(\int_{3}^3 f(x)dx\) (what do you think this even means?)
\(0\) — You can think of this as an infinitely thin rectangle.ans
-
\(\int_{-1}^{0} f(x)dx\).
\(1\)ans
-
\(\int_{0}^{1.5} f(x)dx\).
ans
-
\(\int_{-1.5}^{4.5} f(x)dx\)
\(10.5\)ans
-
\(\int_{-2}^2 f(x)dx\).
-
Remember those problems from homework 1 where we started with a velocity graph and then drew the position graph? Let’s try that again.
-
Draw the position graph corresponding to this velocity graph next to the graph above.
ans
-
Find the following three integrals based on the original graph \(v(t)\):
\(\int_0^3 v(t)dt, \quad \int_0^6 v(t)dt, \quad \int_0^9 v(t)dt.\)
\(60\), \(30\), \(30\)ans -
Your answers for parts (a) and (b) should look the same in some way. How do they look the same, and why did it work out this way?
The answers are the key \(y\)-values from the graph in part (a). This is the same, since in both cases you are doing the same thing: takeing \(\Delta x \cdot y\) (or \(\Delta t \cdot \text{velocity}\) and adding it up as you go.ans
-
Draw the position graph corresponding to this velocity graph next to the graph above.
-
Using \(6\) rectangles and using the left rectangle rule, estimate the area under the curve of the following functions from \(x = 0\) to \(x = 3\).
-
\(e(x) = 2 - x\).
\(\approx 2.25\)ans
-
\(f(x) = -\frac{1}{9} x^2 + 1\)
\(\approx 2.24\)ans
-
\(g(x) = e^x\)
\(\approx 14.71\)ans
-
\(e(x) = 2 - x\).
-
For \(e(x)\) in problem 3, find the exact area using the formula for the area of a triangle.
\(1.5\)ans
-
For \(f(x)\) in problem 3:
- If you haven’t done so already, sketch a picture of the graph as well as the rectangles you used to approximate the area.
-
Is your approximation from problem 3 an
over-estimate
or an
under-estimate
? How do you know?
Overestimate, since it looks like the rectangles cover too much area.ans
- Watch the Khan Academy video on the Trapezoidal method of finding the area under the curve .
-
Using \(6\) trapezoids that match the height of the graph, estimate the area under the curve of the following functions from \(x = 0\) to \(x = 3\).
-
\(e(x) = 2 - x\).
\(1.5\)ans
-
\(f(x) = -\frac{1}{9} x^2 + 1\)
\(1.99\)ans
-
\(g(x) = e^x\)
\(19.48\)ans
-
\(e(x) = 2 - x\).
- Watch this Khan Academy like video on the midpoint formula: click here
-
Using \(6\) rectangles, use the midpoint rule to approximate the area under the curve from \(x = 0\) to \(x = 3\).
-
\(e(x) = 2 - x\).
\(1.5\)ans
-
\(f(x) = -\frac{1}{9} x^2 + 1\)
\(2.03\)ans
-
\(g(x) = e^x\)
\(18.31\)ans
-
\(e(x) = 2 - x\).
- I couldn’t find a Khan Academy explanation of Simpson’s rule, so here is another video by Patrick at Just Math Tutoring .
-
Use Simpson’s rule to approximate the area under the curve. Use \(6\) intervals from \(x = 0\) to \(x = 3\).
-
\(e(x) = 2 - x\).
\(1.5\)ans
-
\(f(x) = -\frac{1}{9} x^2 + 1\)
\(2\)ans
-
\(g(x) = e^x\)
\(\approx 19.09\)ans
-
\(e(x) = 2 - x\).
-
Note that the actual answers for the area under the curve from \(x = 0\) to \(x = 3\) are
- \(1.5\) for \(e(x) = 2-x\).
- \(2\) for \(f(x) = -\frac{1}{9} x^2 + 1\)
- \(19.086\) for \(g(x) = e^x\).
Given these answers, rate the following rules from most accurate to least accurate based on the answers from this homework: left rectangle rule, trapezoid rule, midpoint rule, Simpson’s rule.


<IP_ADDRESS>: Anthem for Doomed Youth
Anthem for Doomed Youth
Anthem for Doomed Youth License: Public DomainWhat passing-bells for these who die as cattle?
Only the monstrous anger of the guns.
Only the stuttering rifles' rapid rattle
Can patter out their hasty orisons.
No mockeries for them; no prayers nor bells,
Nor any voice of mourning save the choirs,—
The shrill, demented choirs of wailing shells;
And bugles calling for them from sad shires.
What candles may be held to speed them all?
Not in the hands of boys, but in their eyes
Shall shine the holy glimmers of goodbyes.
The pallor of girls' brows shall be their pall;
Their flowers the tenderness of patient minds,
And each slow dusk a drawing-down of blinds.


5.1: Introduction
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One of the highlights of being a preschool teacher was setting up my classroom environment at the beginning of each new school year. There was so much anticipation and excitement as I thoughtfully organized my classroom, stocked the learning centers with new materials, and planned curriculum activities. I especially enjoyed purchasing a new lesson plan book and writing up activity plans for each month. I gathered ideas from various teacher resource books that primarily focused on seasonal themes and kindergarten readiness skills – like language arts and math. As I carefully considered topics for each month, I planned for indoor and outdoor activities, music and movement activities, along with a variety of play opportunities. I thought about creative art projects and planned for engaging circle time discussions. I created quiet corners, learning centers, decorated the walls with store-bought posters, and strived to make the classroom environment safe and welcoming. Some twenty years later, as I write this text and reflect on my own experiences as a preschool teacher, there are a few questions that come to mind:
In this chapter, we will examine how observation and documentation are used to develop effective curriculum. We will explore what curriculum is and we will discuss the benefits of planning developmentally appropriate curriculum. Additionally, the teacher’s role will be examined. Lastly, we will discuss how to plan effective and meaningful curriculum using observation, documentation, interpretation, and reflection as best practices.
Figure 5.1 Lesson Plan Concept Mapping . [51]


11.1: Why It Matters- Chi-Square Tests
Why understand the application of chi-square tests using categorical variables?
In this module, Chi-Square Tests , we again focus on inference with categorical variables. We learn three new hypothesis tests, two of which are an extension of hypothesis tests about proportions that we learned in the modules Inference for One Proportion and Inference for Two Proportions . This module does not focus on estimating a parameter, so there is nothing about confidence intervals in this module.
Here is the Big Picture of Statistics with the new material for Chi-Square Tests highlighted in purple.
Following are examples of research questions that procedures in this module can address:
Goodness-of-Fit Test: Test a claim about the distribution of a categorical variable in a population.
- During the presidential election of 2008, the Pew Research Center collected survey data that suggested that 24% of registered voters were liberal, 38% were moderate, and 38% were conservative. Is the distribution of political views different this year?
- The distribution of blood types for whites in the United States is 45% type O, 41% type A, 10% type B, and 4% type AB. Is the distribution of blood types different for Asian Americans?
Test of Independence: Test a claim about the relationship between two categorical variables in a population.
- For young adults in the United States, is gender related to body image?
- Is alcohol abuse by New York firefighters dependent on participation in the 9/11 rescue operation?
- In the United States, is race associated with political views (conservative, moderate, liberal)?
Test of Homogeneity: Test a claim about the distribution of a categorical variable in several populations.
- Does the use of steroids in collegiate athletics differ across the three NCAA divisions?
- Was the distribution of political views (liberal, moderate, conservative) different for the last three presidential elections in the United States?
Contributors and Attributions
- Concepts in Statistics. Provided by : Open Learning Initiative. Located at : http://oli.cmu.edu . License : CC BY: Attribution


17: Electrochemistry
Electrochemistry deals with chemical reactions that produce electricity and the changes associated with the passage of electrical current through matter. The reactions involve electron transfer, and so they are oxidation-reduction (or redox) reactions. Many metals may be purified or electroplated using electrochemical methods. Devices such as automobiles, smartphones, electronic tablets, watches, pacemakers, and many others use batteries for power. Batteries use chemical reactions that produce electricity spontaneously and that can be converted into useful work. All electrochemical systems involve the transfer of electrons in a reacting system. In many systems, the reactions occur in a region known as the cell, where the transfer of electrons occurs at electrodes.
-
- 17.1: Balancing Oxidation-Reduction Reactions
- An electric current consists of moving charge. The charge may be in the form of electrons or ions. Current flows through an unbroken or closed circular path called a circuit. The current flows through a conducting medium as a result of a difference in electrical potential between two points in a circuit. Electrical potential has the units of energy per charge. In SI units, charge is measured in coulombs (C), current in amperes, and electrical potential in volts.
-
- 17.2: Galvanic Cells
- Electrochemical cells typically consist of two half-cells. The half-cells separate the oxidation half-reaction from the reduction half-reaction and make it possible for current to flow through an external wire. One half-cell contains the anode. Oxidation occurs at the anode. The anode is connected to the cathode in the other half-cell. Reduction occurs at the cathode. Adding a salt bridge completes the circuit allowing current to flow.
-
- 17.3: Standard Reduction Potentials
- Assigning the potential of the standard hydrogen electrode (SHE) as zero volts allows the determination of standard reduction potentials, E°, for half-reactions in electrochemical cells. As the name implies, standard reduction potentials use standard states (1 bar or 1 atm for gases; 1 M for solutes, often at 298.15 K) and are written as reductions (where electrons appear on the left side of the equation).
-
- 17.4: The Nernst Equation
- Electrical work is the negative of the product of the total charge (Q) and the cell potential (Ecell). The total charge can be calculated as the number of moles of electrons (n) times the Faraday constant (F = 96,485 C/mol e−). Electrical work is the maximum work that the system can produce and so is equal to the change in free energy. Thus, anything that can be done with or to a free energy change can also be done to or with a cell potential.
-
- 17.5: Batteries and Fuel Cells
- Batteries are galvanic cells, or a series of cells, that produce an electric current. When cells are combined into batteries, the potential of the battery is an integer multiple of the potential of a single cell. There are two basic types of batteries: primary and secondary. Primary batteries are “single use” and cannot be recharged. Dry cells and (most) alkaline batteries are examples of primary batteries. The second type is rechargeable and is called a secondary battery.
-
- 17.6: Corrosion
- Corrosion is the degradation of a metal caused by an electrochemical process. Large sums of money are spent each year repairing the effects of, or preventing, corrosion. Some metals, such as aluminum and copper, produce a protective layer when they corrode in air. The thin layer that forms on the surface of the metal prevents oxygen from coming into contact with more of the metal atoms and thus “protects” the remaining metal from further corrosion. Iron corrodes (forms rust) when exposed to wate
-
- 17.7: Electrolysis
- Using electricity to force a nonspontaneous process to occur is electrolysis. Electrolytic cells are electrochemical cells with negative cell potentials (meaning a positive Gibbs free energy), and so are nonspontaneous. Electrolysis can occur in electrolytic cells by introducing a power supply, which supplies the energy to force the electrons to flow in the nonspontaneous direction. Electrolysis is done in solutions, which contain enough ions so current can flow.
-
- 17.E: Electrochemistry (Exercises)
- These are homework exercises to accompany the Textmap created for "Chemistry" by OpenStax. Complementary General Chemistry question banks can be found for other Textmaps and can be accessed here. In addition to these publicly available questions, access to private problems bank for use in exams and homework is available to faculty only on an individual basis; please contact Delmar Larsen for an account with access permission.
Contributors
-
Paul Flowers (University of North Carolina - Pembroke), Klaus Theopold (University of Delaware) and Richard Langley (Stephen F. Austin State University) with contributing authors. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Download for free at<EMAIL_ADDRESS>).


62: I Studied Buttons for 7 Years and Learned These 5 Lessons about How and Why People Push Them (Plotnick)
Rachel Plotnick
#systemanalysis, #reportinginformation, #research, #proposal, #descriptive, #logos, #science, #history
All day every day, throughout the United States, people push buttons – on coffee makers, TV remote controls and even social media posts they “like.” For more than seven years, I’ve been trying to understand why , looking into where buttons came from, why people love them – and why people loathe them.
As I researched my recent book, “ Power Button: A History of Pleasure, Panic, and the Politics of Pushing ,” about the origins of American push-button society, five main themes stood out, influencing how I understand buttons and button-pushing culture.
1. Buttons aren’t actually easy to use
Just give it a try.
George Eastman Museum/Wikimedia Commons
Public Domain
In the late 19th century, the Eastman Kodak Company began selling button-pushing as a way to make taking photographs easy. The company’s slogan, “You press the button, we do the rest,” suggested it wouldn’t be hard to use newfangled technological devices. This advertising campaign paved the way for the public to engage in amateur photography – a hobby best known today for selfies .
Yet in many contexts, both past and present, buttons are anything but easy. Have you ever stood in an elevator pushing the close-door button over and over , hoping and wondering if the door will ever shut? The same quandary presents itself at every crosswalk button . Programming a so-called “universal remote” is often an exercise in extreme frustration . Now think about the intensely complex dashboards used by pilots or DJs.
For more than a century, people have been complaining that buttons aren’t easy : Like any technology, most buttons require training to understand how and when to use them.
Pilots need a lot of training and practice to know what to do with all those buttons. U.S. Air Force/Kelly White, Public Domain.
2. Buttons encourage consumerism
The earliest push buttons appeared on vending machines, as light switches and as bells for wealthy homeowners to summon servants.
At the turn of the 20th century, manufacturers and distributors of push-button products often tried to convince customers that their every whim and desire could be gratified at a push – without any of the mess, injury or effort of previous technologies like pulls, cranks or levers. As a form of consumption, button pushing remains pervasive: People push for candy bars and tap for streaming movies or Uber rides.
Just press here and get more detergent.
Alexander Klink/Wikimedia Commons
,
CC BY
Amazon’s “Dash” button takes push-button pleasure to the extreme. It’s tempting to think about affixing single-purpose buttons around your house, ready to instantly reorder toilet paper or laundry detergent. But this convenience comes at a price: Germany recently outlawed Dash buttons , because they don’t let customers know how much they’ll pay when they place an order.
3. Button-pushers are often seen as abusive
Throughout my research, I discovered that people worry that buttons will fall into the wrong hands or be used in socially undesirable ways. My children will push just about any button within their reach – and sometimes those not within reach, too. The children of the late 19th and early 20th centuries were the same. People often complained about children honking automobile horns, ringing doorbells and otherwise taking advantage of buttons that looked fun to press.
Adults, too, often received criticism for how they pushed. In the past, managers triggered ire for using push-button bells to keeping their employees at their beck and call, like servants. More recently there are stories in the news about disgraced figures like Matt Lauer using buttons to control the comings and goings of his staff, taking advantage of a powerful position.
4. Some of the most-feared buttons aren’t real
Beginning in the late 1800s, one of the most common fears registered about buttons involved warfare and advanced weapons: Perhaps one push of a button could blow up the world.
Fortunately, starting a nuclear war is a bit harder than this. Image by
Steve Watts
from
Pixabay
This anxiety has persisted from the Cold War to the present, playing prominently in movies like “ Dr. Strangelove ” and in news headlines . Although no such magic button exists, it’s a potent icon for how society often thinks about push-button effects as swift and irrevocable. This concept is also useful in geopolitics. As recently as 2018, President Donald Trump bragged to North Korean leader Kim Jong Un over Twitter that “ I too have a Nuclear Button , but it is a much bigger & more powerful one than his, and my Button works!”
5. Not a lot has changed in more than a century
As I completed my book, I was struck by how much voices of the past echoed those of the present when discussing buttons. Since the 1880s, American society has deliberated about whether button pushing is a desirable or dangerous form of interaction with the world.
Persistent concerns remain about whether buttons make life too easy, pleasurable or rote. Or, on the flip side, observers worry that buttons increase complexity, forcing users to fiddle unnecessary with “ unnatural ” interfaces.
Yet as much as people have complained about buttons over the years, they remain stubbornly present – an entrenched part of the design and interactivity of smartphones, computers, garage door openers, car dashboards and videogame controllers.
As I suggest in “Power Button,” one way to remedy this endless discussion about whether buttons are good or bad is to instead begin paying attention to power dynamics – and the ethics – of push buttons in everyday life. If people begin to examine who gets to push the button, and who doesn’t, in what contexts, under which conditions, and to whose benefit, they might begin to understand buttons’ complexity and importance.
____________________
Rachel Plotnick is Assistant Professor of Cinema and Media Studies at Indiana University and the author of Power Button: A History of Pleasure, Panic and the Politics of Pushing. Her essay first appeared in The Conversation.
I Studied Buttons for 7 Years and Learned These 5 Lessons about How and Why People Push Them by Rachel Plotnick is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License .


30.20: Plant Sensory Systems and Responses - Plant Responses to Gravity
- Describe the role of amyloplasts in gravitropism
Whether or not they germinate in the light or in total darkness, shoots usually sprout up from the ground, while roots grow downward into the ground. A plant laid on its side in the dark will send shoots upward when given enough time. Gravitropism ensures that roots grow into the soil and that shoots grow toward sunlight. Growth of the shoot apical tip upward is called negative gravitropism, whereas growth of the roots downward is called positive gravitropism.
Time-lapse of pea shoot and root growth : Time-lapse of a pea plant growing from seed, showing both the shoot and root system. The roots grown downward in the direction of gravity, which is positive gravitropism, and the shoot grows upward away from gravity, which is negative gravitropism.
The reason plants know which way to grow in response to gravity is due to amyloplasts in the plants. Amyloplasts (also known as statoliths ) are specialized plastids that contain starch granules and settle downward in response to gravity. Amyloplasts are found in shoots and in specialized cells of the root cap. When a plant is tilted, the statoliths drop to the new bottom cell wall. A few hours later, the shoot or root will show growth in the new vertical direction.
The mechanism that mediates gravitropism is reasonably well understood. When amyloplasts settle to the bottom of the gravity-sensing cells in the root or shoot, they physically contact the endoplasmic reticulum (ER). This causes the release of calcium ions from inside the ER. This calcium signaling in the cells causes polar transport of the plant hormone indole acetic acid (IAA) to the bottom of the cell. In roots, a high concentration of IAA inhibits cell elongation. The effect slows growth on the lower side of the root while cells develop normally on the upper side. IAA has the opposite effect in shoots, where a higher concentration at the lower side of the shoot stimulates cell expansion and causes the shoot to grow up. After the shoot or root begin to grow vertically, the amyloplasts return to their normal position. Other hypotheses, which involve the entire cell in the gravitropism effect, have been proposed to explain why some mutants that lack amyloplasts may still exhibit a weak gravitropic response.
Key Points
- Positive gravitropism occurs when roots grow into soil because they grow in the direction of gravity while negative gravitropism occurs when shoots grow up toward sunlight in the opposite direction of gravity.
- Amyloplasts settle at the bottom of the cells of the shoots and roots in response to gravity, causing calcium signaling and the release of indole acetic acid.
- Indole acetic acid inhibits cell elongation in the lower side of roots, but stimulates cell expansion in shoots, which causes shoots to grow upward.
Key Terms
- amyloplast : a non-pigmented organelle found in some plant cells that is responsible for the synthesis and storage of starch granules through the polymerization of glucose
- statolith : a specialized form of amyloplast involved in graviperception by plant roots and most invertebrates
- gravitropism : a plant’s ability to change its growth in response to gravity


5.5: Rodriguez v. US 575 US___(2015)
NOTE: Where it is feasible, a syllabus (headnote) will be released, as is being done in connection with this case, at the time the opinion is issued.The syllabus constitutes no part of the opinion of the Court but has been prepared by the Reporter of Decisions for the convenience of the reader.See United States v. Detroit Timber & Lumber Co., 200 U. S. 321 .
SUPREME COURT OF THE UNITED STATES
Syllabus
RODRIGUEZ v . UNITED STATES
certiorari to the united states court of appeals for the eighth circuit
No. 13–9972. Argued January 21, 2015—Decided April 21, 2015
Officer Struble, a K–9 officer, stopped petitioner Rodriguez for driving on a highway shoulder, a violation of Nebraska law. After Struble attended to everything relating to the stop, including, inter alia, checking the driver’s licenses of Rodriguez and his passenger and issuing a warning for the traffic offense, he asked Rodriguez for permission to walk his dog around the vehicle. When Rodriguez refused, Struble detained him until a second officer arrived. Struble then retrieved his dog, who alerted to the presence of drugs in the vehicle. The ensuing search revealed methamphetamine. Seven or eight minutes elapsed from the time Struble issued the written warning until the dog alerted.
Rodriguez was indicted on federal drug charges. He moved to suppress the evidence seized from the vehicle on the ground, among others, that Struble had prolonged the traffic stop without reasonable suspicion in order to conduct the dog sniff. The Magistrate Judge recommended denial of the motion. He found no reasonable suspicion supporting detention once Struble issued the written warning. Under Eighth Circuit precedent, however, he concluded that prolonging the stop by “seven to eight minutes” for the dog sniff was only a de minimis intrusion on Rodriguez’s Fourth Amendment rights and was for that reason permissible. The District Court then denied the motion to suppress. Rodriguez entered a conditional guilty plea and was sentenced to five years in prison. The Eighth Circuit affirmed. Noting that the seven or eight minute delay was an acceptable “ de minimis intrusion on Rodriguez’s personal liberty,” the court declined to reach the question whether Struble had reasonable suspicion to continue Rodriguez’s detention after issuing the written warning.
Held:
1. Absent reasonable suspicion, police extension of a traffic stop in order to conduct a dog sniff violates the Constitution’s shield against unreasonable seizures.
A routine traffic stop is more like a brief stop under Terry v. Ohio , 392 U. S. 1 , than an arrest, see, e.g., Arizona v. Johnson , 555 U. S. 323 . Its tolerable duration is determined by the seizure’s “mission,” which is to address the traffic violation that warranted the stop, Illinois v. Caballes , 543 U. S. 405 and attend to related safety concerns. Authority for the seizure ends when tasks tied to the traffic infraction are—or reasonably should have been—completed. The Fourth Amendment may tolerate certain unrelated investigations that do not lengthen the roadside detention, Johnson , 555 U. S., at 327–328 (questioning); Caballes , 543 U. S., at 406, 408 (dog sniff), but a traffic stop “become[s] unlawful if it is prolonged beyond the time reasonably required to complete th[e] mission” of issuing a warning ticket, id., at 407.
Beyond determining whether to issue a traffic ticket, an officer’s mission during a traffic stop typically includes checking the driver’s license, determining whether there are outstanding warrants against the driver, and inspecting the automobile’s registration and proof of insurance. These checks serve the same objective as enforcement of the traffic code: ensuring that vehicles on the road are operated safely and responsibly. See Delaware v. Prouse , 440 U. S. 648 –659. Lacking the same close connection to roadway safety as the ordinary inquiries, a dog sniff is not fairly characterized as part of the officer’s traffic mission.
In concluding that the de minimis intrusion here could be offset by the Government’s interest in stopping the flow of illegal drugs, the Eighth Circuit relied on Pennsylvania v. Mimms , 434 U. S. 106 . The Court reasoned in Mimms that the government’s “legitimate and weighty” interest in officer safety outweighed the “ de minimis ” additional intrusion of requiring a driver, lawfully stopped, to exit a vehicle, id., at 110–111. The officer-safety interest recognized in Mimms , however, stemmed from the danger to the officer associated with the traffic stop itself. On-scene investigation into other crimes, in contrast, detours from the officer’s traffic-control mission and therefore gains no support from Mimms .
The Government’s argument that an officer who completes all traffic-related tasks expeditiously should earn extra time to pursue an unrelated criminal investigation is unpersuasive, for a traffic stop “prolonged beyond” the time in fact needed for the officer to complete his traffic-based inquiries is “unlawful,” Caballes , 543 U. S., at 407. The critical question is not whether the dog sniff occurs before or after the officer issues a ticket, but whether conducting the sniff adds time to the stop. Pp. 5–8.
2. The determination adopted by the District Court that detention for the dog sniff was not independently supported by individualized suspicion was not reviewed by the Eighth Circuit. That question therefore remains open for consideration on remand. P. 9.
741 F. 3d 905, vacated and remanded.
Ginsburg, J., delivered the opinion of the Court, in which Roberts, C. J., and Scalia, Breyer, Sotomayor, and Kagan, JJ., joined. Kennedy, J., filed a dissenting opinion. Thomas, J., filed a dissenting opinion, in which Alito, J., joined, and in which Kennedy, J., joined as to all but Part III. Alito, J., filed a dissenting opinion.
Contributors and Attributions
- Authored by : US Government . Located at : https://supreme.justia.com/cases/federal/us/575/13-9972/ . License : Public Domain: No Known Copyright


2.24: Characteristics of Genres
- Explain differences between the characteristics of various genres of texts
Even though the previous examples all were about cars in some way, you no doubt realized they were very different in tone, style, and quality.
Let’s take a closer look at each.
Example 1
“Electric and Plug-in Hybrids,” by George Crabtree, came from OpenStax CNX , a textbook publisher.
The full source demonstrates some features common to textbooks:
- clearly stated learning outcomes for each section
- formal tone
- direct language
- definitions of key terms
- no in-text citations, though references may be included at the end of a chapter
- images to help illustrate the topic
Example 2
“Will the Tesla Model 3 recharge the U.S. electric vehicle market?” by David Keith, came from The Conversation , an online news source.
The full article demonstrates some features common to journalism:
- most important information appears near the opening of the article
- reports facts
- quotes and interviews from experts on the topic
- no in-text citations, no citations at the end
- embedded links to related sources
- images to help illustrate the topic
Example 3
“Cannibalism in the Cars,” by Mark Twain, came from a collection of his short stories, Sketches New and Old .
The full story demonstrates some features common to literature:
- introduces characters
- follows a narrative sequence of events, revealing a plot
- includes description to set scene
- may use first-person, second-person, or third-person voice
- uses dialogue to convey what characters say to one another
- no in-text citations, no citations at the end
Example 4
“Hybrid vehicle” came from Wikipedia , the well-known online encyclopedia.
The full story demonstrates some features common to reference material:
- highly structured and organized text, using headings and sub-headings
- factual content
- includes in-text citation (or footnotes) and a list of references at the end
- embedded links to related sources
- historical information
- images to help illustrate the topic
- formal tone
- clear and easy to read
Example 5
“The Influence of Intersections on Fuel Consumption in Urban Arterial Road Traffic: A Single Vehicle Test in Harbin, China,” by Lina Wu, Yusheng Ci, Jiangwei Chu, and Hongsheng Zhang, came from PLoS One , an online academic journal.
The full article demonstrates some features common to academic journal content:
- highly structured and organized text, using headings and sub-headings
- describes an experiment or an analysis, including the authors’ findings and interpretations
- includes in-text citation (or footnotes) and a list of References at the end
- advanced vocabulary, specific to the field of study
- images to help illustrate the topic
Contributors and Attributions
- Text: Comparing Genres, Conclusion. Provided by : Lumen Learning. License : CC BY: Attribution
- Image of OpenStax CNX logo. Provided by : OpenStax CNX. Located at : http://cnx.org/ . License : CC BY: Attribution
- Image of The Conversation logo. Provided by : The Conversation. Located at : http://theconversation.com/us . License : CC BY-NC-ND: Attribution-NonCommercial-NoDerivatives
- Image of Wikipedia logo. Provided by : Wikipedia. Located at : commons.wikimedia.org/wiki/File:Wikipedia-logo-en-big.png. License : CC BY-SA: Attribution-ShareAlike
- Image of PLoS One logo. Provided by : PLoS One. Located at : http://journals.plos.org/plosone/ . License : CC BY: Attribution
- Image of Sketches New and Old. Located at : http://www.gutenberg.org/files/3189/3189-h/3189-h.htm . License : Public Domain: No Known Copyright


27.9A: Fetal Development
At the end of the 10th week of gestation, the fetal period begins.
- Outline the progression of fetal development from 11 weeks to 40 weeks
Key Points
- Although fetuses can be adversely affect by environmental toxicants, they are less sensitive to them than embryos because the precursors for most organs are already formed.
- At the start of the fetal stage, the fetus is typically about 30 millimeters in length from crown to rump, and weighs about eight grams. The head makes up nearly half of the fetus’ size.
- The precursors of all the major organs are created by the time the fetal period begins. Therefore, the fetal period is described both by organ and a list of the changes by weeks of gestational age.
Key Terms
- meconium : The earliest stool of a mammalian infant. Unlike later feces, meconium is composed of materials ingested during the time the infant spends in the uterus (intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile, and water).
- gestational age : This relates to the age of an embryo or fetus (or newborn infant). In human obstetrics, this age is often defined as the time elapsed since 14 days prior to fertilization; this is approximately the duration since the woman’s last menstrual period began.
- lanugo : Soft down or fine hair that covers the human fetus.
In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the ninth week after fertilization. Since the precursors of all the major organs are created by this time, the fetal period is described both by organ and a list of changes by weeks of gestational age.
All major structures are already formed in the fetus, but they continue to grow and develop. Therefore, the fetus is not as sensitive to damage from environmental exposures as the embryo, though toxic exposures often cause physiological abnormalities, growth retardation, or minor congenital malformations.
At the start of the fetal stage, the fetus is typically about 30 millimeters in length from crown to rump and weighs about eight grams. The head makes up nearly half of the fetus’ size. The four-chamber heart is finishing development, and the embryonic tail goes away. The breathing-like movement of the fetus is necessary for stimulation of lung development, rather than for obtaining oxygen.
- Week 10: Finger nails and hair start to grow. The heart, hands, feet, brain, and other organs are present, but are only at the beginning of development and have minimal operation.
- Week 11: Nearly all structures and organs are formed. Fingers and toes are separated and the genitals begin to take on the proper gender characteristics.
- Week 12: The digestive system and liver function. The pancreas makes insulin.
- Week 13: The fetus begins to get its nourishment from the placenta and the veins and organs are visible through the skin.
- Week 14: The kidneys produce urine, and the liver makes bile. In boys, the prostate gland develops, while in girls the ovaries move from the abdomen to the pelvis.
- Weeks 15 to 16: The heart pumps out 25 quarts of blood a day and the fetal structures are looking more normal.
- Week 17: The fetus start to move its joints and the retina becomes sensitive to light. It weighs about five ounces.
- Week 18: The fetus starts to hear and is startled by noise. Its skin is starting to grow a protective, wax-like layer and tiny air spaces begin to form in the lungs and the vocal cords.
- Week 19: The brain is designating areas for the five senses.
- Week 20: The fetus weighs about 10 ½ oz, swallows more, and produces meconium.
- Week 21: The eyebrows and lids are present, and for the female fetus, the vagina begins to form.
- Week 22: Tiny tooth buds beneath the gums develops. The eyes form, but the irises lack pigment.
- Week 23: The fetus weighs over a pound. It can feel movements and hear sounds. Blood vessels in his/her lungs are developing to prepare for breathing.
- Week 24: The fetus is almost a foot long. The lungs are developing branches of the respiratory tree as well as cells that produce surfactant, a substance that will help the air sacs inflate once born.
- Week 25: The amount of body fat rapidly increases. The lungs are not fully mature. The bones are fully developed, but are still soft and pliable. Thalamic brain connections form that mediate sensory input. Iron, calcium, and phosphorus become more abundant. The fingernails reach the end of the fingertips. The lanugo, or fine hair, begins to disappear, until it is gone (except on the upper arms and shoulders). Small breast buds are present on both sexes. Head hair becomes coarse and thicker.
Birth is imminent and occurs around the 40th week. The fetus is considered full-term between weeks 37 and 40, which means that the fetus is considered sufficiently developed for life outside the uterus.