Exam 4: HESI-A2-Reading

Brain Freeze "Brain Freeze" headaches-known to scientists as sphenopalatine ganglioneuralgia -are most often triggered when cold food or drink comes into contact with the roof of your mouth. In order to discover more about this phenomenon, researchers at Harvard Medical School hooked volunteers up to trans-cranial Dopplers, machines that allow scientists to study blood flow in the brain. The volunteers were then given cups of ice water and instructed to drink it using a straw held right up against the roof of the mouth. The volunteer gave a signal when he or she felt a "brain freeze" headache begin and another signal when it ended. This experiment allowed the scientists to observe changes in brain blood flow before, during, and after a "brain freeze" headache. The scientists found that when the subjects were experiencing a "brain freeze", the anterior cerebral artery (a major blood vessel in the brain) dilated rapidly. Because the artery becomes wider, more blood flows into the brain. This creates an increase in pressure inside the skull, which is what causes the pain. As soon as the artery shrinks to its normal size, the "brain freeze" headache disappears. This may explain why "brain freeze" headaches hurt, but it does not tell us why they happen in the first place. Scientists do not yet have any definite answers to this question, but they do have some ideas. One theory suggested by the researchers at Harvard Medical School is that a brain freeze is a way of protecting the brain from cold. When the anterior cerebral artery dilates, it allows a flood of warm blood inside the brain, thus keeping it warm. According to the text, what was NOT a purpose of the experiment mentioned in paragraph 2?

Synaesthesia Does the number five smell like lemons? Is the sound of a flute purple? Does the letter "R" taste like cinnamon? These questions might seem strange, but to people with synaesthesia, they make perfect sense. Synaesthesia is a neurological phenomenon where the senses get crossed. People with synaesthesia (also called "synaesthetes") experience this phenomenon in different ways. The most common form of synaesthesia is called color-graphemic synaesthesia. People who experience this form of synaesthesia associate letters and numbers with certain colors. For example, the letter "A" might always appear to be red and the number eight might always look blue. Another common form of synaesthesia is chromesthesia: the association of sounds with colors. Some people who experience this phenomenon see bursts of color when they hear everyday sounds, such as dogs barking or water dripping. Others associate specific colors with different musical notes. Although scientists do not yet understand what causes some people to experience synaesthesia, some researchers argue for something called the cross-activation theory. This theory suggests that the regions of the brain responsible for interpreting information from the different senses have become "crossed," that is, the neurons from one sense inadvertently activate the neurons from another sense. There is also evidence to suggest that synaesthesia is a genetic trait. While there is no treatment for synaesthesia, there is also not much demand for a treatment; most synaesthetes report that they find their condition rather pleasant. Question: Which of the following is true about color-graphemic synaesthesia?

Soda Ban Cigarettes. Alcohol. Drugs. Most people agree that these things should be kept away from children and only consumed by adults in limited quantities, if at all. Is the same thing true for soda? A 20-ounce-bottle of soda has over sixteen teaspoons of sugar in it. This is twice the amount of sugar that the American Heart Association recommends a person should eat in an entire day. Furthermore, this 20-ounce bottle of soda delivers over 200 calories and no nutritive value; soda contains no vitamins, minerals, fiber, protein, or other nutrients. Drinking sodas and other sugary beverages can cause serious health problems. Consuming too many of these sugar-filled beverages may increase your risk for developing type 2 diabetes, obesity, heart disease, tooth decay, and certain kinds of cancer. Studies have also shown that people who drink soda tend to develop a condition known as metabolic syndrome. Metabolic syndrome is a condition characterized by excess abdominal fat, high blood pressure, elevated blood sugar, high levels of triglycerides, and low levels of HDL cholesterol (commonly referred to as "good cholesterol"). Some places have already taken steps to reduce the amount of soda people consume. In California, for example, cafeterias and vending machines in grade schools can not sell soda. The city of Philadelphia also recently added a tax on sugary beverages, making sodas more expensive to purchase. Soda may taste good, but it is terrible for your health. There should be more bans and taxes to keep people from drinking these harmful beverages. Which of these options is an example of opinion, rather than factual information?

Antibiotic Resistance Antibiotic resistance occurs when micro-organisms develop means of survival despite exposure to antibiotics. The development of antibiotic resistance can be traced to two main areas of antibiotic misuse: over-prescription by doctors and unnecessary introduction into animal feed by farmers. The overuse of antibiotics by both doctors and farmers has increased antibiotic resistance by inadvertently fostering natural selection for resistance in colonies of bacteria. Bacteria that naturally carry antibiotic-resistant genes survive contact with the antibiotics. These resistant bacteria then reproduce, transferring their resistant genes to future generations of bacteria. Over time, this process yields a colony of bacteria that is fully resistant to antibiotics. Some bacteria even develop a variety of resistance genes; these bacteria are colloquially known as "superbugs" because of their ability to resist the majority of antibiotics. Staphylococcus aureus, the bacteria responsible for what is commonly known as a "Staph infection," is one of the most resistant pathogens. It is estimated that half of all Staph infections in the United States are resistant to penicillin, methicillin, tetracycline, and erythromycin-the four most common drugs used to treat such infections. The ever-increasing strength and population of these "superbugs" may pose a serious threat to human health in the near future. The problem of antibiotic resistance has no easy solution. More funding should be available to scientists working toward the research and development of new antibiotics that will fight resistant bacteria. There are also steps that laypeople should take to help prevent further development of resistant bacteria. Individuals with viral infections should not demand antibiotics from their doctors. Consumers should also put pressure on meat manufacturers to stop adding unnecessary antibiotics into animals' diets. Finally, citizens should petition the government to increase funding for scientific research done to combat the growing problem of antibiotic resistance. Question: What is the best meaning of the word 'combat' in the last sentence of the passage?

Sports Drinks When you sweat heavily, your body loses electrolytes and water. The most important electrolytes are potassium and sodium-these substances keep your body's cells working properly. Commercials for sports drinks claim that their products will replenish the electrolytes lost during exercise. However, sports drinks are not really necessary for most people. Eating a normal diet that contains healthy amounts of sodium and potassium will maintain the electrolyte balance in your body. Unless you are exercising very intensely for more than 60 minutes, you do not need to use a sports drink to replace lost electrolytes. Most people believe that sports drinks are healthy beverages-after all, if athletes drink them, they must be good for you. On the contrary, sports drinks are filled with artificial ingredients and sugar. One 20-ounce bottle of an average sports drink contains 34 grams of sugar and 130 calories. These empty calories can actually cause you to gain weight instead of helping to keep you fit. One study presented at the 2012 Obesity Society's annual scientific meeting revealed that teenagers gained an average of 3.5 pounds every two years just by consuming a bottle of sports drink every day. The best beverage for you to drink before, during, or after a workout is water. Water has no sugar, no salt, no calories, and no artificial flavors or colors. Water will rehydrate your body and quench your thirst better than any other drink. Unless you are a serious athlete who regularly exercises for more than 60 minutes at a time, sports drinks ultimately do more harm than good. Question: According to the author, which of the following groups could possibly benefit from drinking sports drinks?

PTSD in Female Veterans Post-traumatic stress disorder (PTSD) is a severe anxiety disorder that affects millions of people around the world. Individuals can develop PTSD after experiencing any event that results in psychological trauma. Symptoms of PTSD involve flashbacks to the traumatic event, nightmares, obsessive behavior, anger, insomnia, difficulty concentrating, and hypervigilance. Individuals who suffer from PTSD can experience significant difficulties in social relationships, have lower self-esteem, and have trouble maintaining employment. People with PTSD experience a higher risk of committing suicide and developing a substance abuse disorder. Although PTSD can affect any individual, military veterans are especially susceptible. Furthermore, within this population, women are more than twice as likely as men to develop PTSD. Although studies investigating precisely why women are more likely than men to experience PTSD have not yet been completed, some experts have theorized that low unit cohesion is a major factor. Unit cohesion, defined as the mutual bonds of friendship and support among members of a military unit, is thought to be helpful in reducing the incidence of developing PTSD. Women are more likely than men to experience low unit cohesion for a variety of reasons. One of the most obvious factors is the relative lack of females in the military; currently, women make up only 20% of the armed forces. Pervasive male prejudice against women is another factor that can diminish unit cohesion for female soldiers. Perhaps the biggest impediment to achieving quality treatment for women suffering from wartime PTSD is a shortage of research. While both the VA and independent agencies have completed hundreds of studies researching the prevention of and treatment for PTSD amongst general military populations, there have been no studies completed that solely target women. More must be done to help women who have sacrificed so much for their country. Question: Which of the following is NOT a symptom of PTSD?

DYour Bones At birth, the human body contains over 270 bones. However, as the body grows, some of these bones fuse together. The average adult body contains 206 bones. Together, these bones form the skeleton. The skeleton has many vital functions, including protecting internal organs, providing support, enabling movement, generating blood cells, storing calcium, and helping to regulate the endocrine system. Although we only have one skeleton, it is divided into two major regions: the axial and the appendicular skeletons. The former refers to everything on the body's middle axis, such as the skull, sternum, and vertebrae, while the latter refers to the bones that make up the arms, legs, pelvis, and shoulder girdle. These bones include the femur, the tibia, the ulna, and the radius. Bones are further classified according to their shape and function. The five classifications of bones are: long, short, flat, irregular, and sesamoid bones. Long bones include the fibula and tibia. The carpal bones in the wrist are examples of short bones. Flat bones are thin and curved, and include the ribs, the sternum, and some skull bones. Irregular bones, such as the vertebrae and some facial bones, have complex shapes. Finally, sesamoid bones are small, round bones that form in tendons. There are sesamoid bones in the hands, wrists, and feet, but the most familiar sesamoid bone is the patella, or kneecap. Question: What is the meaning of the phrase 'fuse together' in the sentence 'some of these bones fuse together' in the first paragraph?

Soda Ban Cigarettes. Alcohol. Drugs. Most people agree that these things should be kept away from children and only consumed by adults in limited quantities, if at all. Is the same thing true for soda? A 20-ounce-bottle of soda has over sixteen teaspoons of sugar in it. This is twice the amount of sugar that the American Heart Association recommends a person should eat in an entire day. Furthermore, this 20-ounce bottle of soda delivers over 200 calories and no nutritive value; soda contains no vitamins, minerals, fiber, protein, or other nutrients. Drinking sodas and other sugary beverages can cause serious health problems. Consuming too many of these sugar-filled beverages may increase your risk for developing Type 2 diabetes, obesity, heart disease, tooth decay, and certain kinds of cancer. Studies have also shown that people who drink soda tend to develop a condition known as metabolic syndrome. Metabolic syndrome is a condition characterized by excess abdominal fat, high blood pressure, elevated blood sugar, high levels of triglycerides, and low levels of HDL cholesterol (commonly referred to as "good cholesterol"). Some places have already taken steps to reduce the amount of soda people consume. In California, for example, cafeterias and vending machines in grade schools can not sell soda. The city of Philadelphia also recently added a tax on sugary beverages, making sodas more expensive to purchase. Soda may taste good, but it is terrible for your health. There should be more bans and taxes to keep people from drinking these harmful beverages. What is the main idea of the passage?

Brain Freeze "Brain Freeze" headaches-known to scientists as sphenopalatine ganglioneuralgia -are most often triggered when cold food or drink comes into contact with the roof of your mouth. In order to discover more about this phenomenon, researchers at Harvard Medical School hooked volunteers up to trans-cranial Dopplers, machines that allow scientists to study blood flow in the brain. The volunteers were then given cups of ice water and instructed to drink it using a straw held right up against the roof of the mouth. The volunteer gave a signal when he or she felt a "brain freeze" headache begin and another signal when it ended. This experiment allowed the scientists to observe changes in brain blood flow before, during, and after a "brain freeze" headache. The scientists found that when the subjects were experiencing a "brain freeze", the anterior cerebral artery (a major blood vessel in the brain) dilated rapidly. Because the artery becomes wider, more blood flows into the brain. This creates an increase in pressure inside the skull, which is what causes the pain. As soon as the artery shrinks to its normal size, the "brain freeze" headache disappears. This may explain why "brain freeze" headaches hurt, but it does not tell us why they happen in the first place. Scientists do not yet have any definite answers to this question, but they do have some ideas. One theory suggested by the researchers at Harvard Medical School is that a brain freeze is a way of protecting the brain from cold. When the anterior cerebral artery dilates, it allows a flood of warm blood inside the brain, thus keeping it warm. What is the meaning of the word 'dilate' in the phrase "the anterior cerebral artery dilated rapidly" in paragraph 2?

The Spread of Yellow Fever Yellow fever is a dangerous disease that is primarily found in tropical climates. Sometimes, people infected with yellow fever suffer only mild flu-like symptoms. In other cases, however, yellow fever can be much more serious, causing kidney problems, liver failure, and sometimes, even death. For many years, people believed that the disease was spread from person to person, much like the cold or flu. However, this was not the case. It took the dedicated research of a doctor named Carlos Juan Finlay to show people how to prevent a disease that was killing people by the thousands. In the 1800's, yellow fever was a serious threat to Cuba's population. Because people believed that the disease was spread from person to person, they tried to prevent the spread of the disease by quarantining people. However, this did not help. Dr) Finlay had a different hypothesis. He noticed the worst outbreaks of yellow fever happened when mosquitoes were most active. This led him to theorize that mosquitoes spread the disease, not people. This was a revolutionary idea; no one had considered the possibility of mosquitoes being vectors of disease. In fact, the idea was so revolutionary that no one believed Finlay for over 20 years. Eventually, Finlay's theory was proven. A team of military doctors led by Dr. Walter Reed conducted a series of experiments that proved once and for all that mosquitoes were indeed responsible for spreading yellow fever. Armed with this information, people took new measures to protect themselves from yellow fever. As a result of this discovery, yellow fever has almost completely disappeared from Cuba and many other nations. Why does the author include the sentence "This was a revolutionary idea; no one had considered the possibility of mosquitoes being vectors of disease," in paragraph 3?

Wrinkles Skin wrinkles are caused by a variety of factors. Some of these factors are intrinsic, meaning that you cannot control them because they occur naturally. Others are extrinsic, meaning that they are caused by circumstances outside of the body. One intrinsic factor is aging. As you age, your skin loses collagen, which is the protein responsible for keeping your skin elastic. With less collagen, your skin becomes thinner and more fragile. Aging also reduces the functioning of sweat and oil glands, which work to keep the skin looking smooth. You also lose fat in the deeper layers of your skin as you age. This fat loss causes your skin to sag and develop deeper wrinkles. The two most common extrinsic factors are exposure to ultraviolet radiation (UV rays) and smoking. UV rays in sunlight break down your skin's connective tissue and collagen fibers. To prevent the appearance of wrinkles (as well as protect yourself from skin cancer), you should always use UV-blocking sunscreen. The nicotine in cigarettes is the most likely link between smoking and wrinkles. Nicotine narrows the blood vessels, reducing the blood supply to your skin tissue. This deprives your skin of oxygen and important nutrients, causing damage that contributes to wrinkles. Question: What is the primary purpose of the passage?

Autism and Vaccines Autism spectrum disorders (ASD) are a range of psychological conditions characterized by challenges with social interaction, behavior, speech, and nonverbal communication. While there is no general consensus among medical professionals about the underlying causes of ASD, theories range from genetic inheritance to environmental factors. One of the most controversial theories to have emerged in recent times is that ASD could be caused by the MMR [mumps, measles, rubella] vaccine that was first developed in the 1960's. The vaccine is a mixture of three live viruses and is administered via injection to children when they are one year old. By the late 1990's, this vaccination had led to the near-eradication of measles in countries that employed widespread inoculation. However, a combination of spurious scientific data and alarmist media attention led to an entirely preventable resurgence in measles cases in the early 21^st century. The first claims of a connection between the MMR vaccine and autism were made in 1998, when an article in The Lancet, a respected British medical journal, reported on eight cases of autism that could possibly be traced back to the administration of an MMR vaccine. An onslaught of media coverage followed the publication of this article. The popular press quickly seized upon this story; in 2002, over 1200 articles were written about the link between MMR vaccines and ASD. Less than 30% of these articles, however, mentioned that an overwhelming amount of scientific evidence suggested that these vaccinations were completely safe. Question: Which of the following statements best describes the point of view of the author?

The Pilomotor Reflex Have you ever experienced the pilomotor reflex? Chances are that you have. The pilomotor reflex is actually something most people experience every day: goosebumps. Goosebumps (also called goose flesh and goose pimples) are small bumps on the skin. They are created when tiny muscles beneath the hairs on your skin contract, pulling the hair into an upright position. They can occur anywhere that you have hair on your body, but they are most common on your arms and legs. Goosebumps are an involuntary reaction to many different sensations, such as cold, fear, or even happiness. Humans are not the only animals that get goosebumps. When cats or dogs are threatened by an enemy, the pilomotor reflex will cause their fur to stand on end. This makes the animal look larger, which might scare away the enemy. Porcupines also experience the pilomotor reflex; a frightened porcupine will raise its quills when it is in danger. This not only makes the porcupine look bigger, it frightens enemies away by drawing attention to the sharp quills. The pilomotor reflex can also help animals stay warm by trapping body heat closer to their skin. Because human beings have much less body hair than most other animals, goosebumps do not make us seem larger or more intimidating. They also do not help to keep us very warm, although they do help to prevent some heat from leaving the body. For the most part, the pilomotor reflex is much more important for animals than it is for people. In fact, many scientists think that the pilomotor reflex is actually completely useless for humans. Question: What is the main idea of the passage?

The Spread of Yellow Fever Yellow fever is a dangerous disease that is primarily found in tropical climates. Sometimes, people infected with yellow fever suffer only mild flu-like symptoms. In other cases, however, yellow fever can be much more serious, causing kidney problems, liver failure, and sometimes, even death. For many years, people believed that the disease was spread from person to person, much like the cold or flu. However, this was not the case. It took the dedicated research of a doctor named Carlos Juan Finlay to show people how to prevent a disease that was killing people by the thousands. In the 1800's, yellow fever was a serious threat to Cuba's population. Because people believed that the disease was spread from person to person, they tried to prevent the spread of the disease by quarantining people. However, this did not help. Dr) Finlay had a different hypothesis. He noticed the worst outbreaks of yellow fever happened when mosquitoes were most active. This led him to theorize that mosquitoes spread the disease, not people. This was a revolutionary idea; no one had considered the possibility of mosquitoes being vectors of disease. In fact, the idea was so revolutionary that no one believed Finlay for over 20 years. Eventually, Finlay's theory was proven. A team of military doctors led by Dr. Walter Reed conducted a series of experiments that proved once and for all that mosquitoes were indeed responsible for spreading yellow fever. Armed with this information, people took new measures to protect themselves from yellow fever. As a result of this discovery, yellow fever has almost completely disappeared from Cuba and many other nations. According to the text, which of the following is true regarding mosquitoes?

Does Low Body Temperature Cause Illness? As children, we are often told to dress warmly in the winter so we do not get sick. This is a common piece of advice, but is there any truth behind it? In fact, there is no scientific evidence to suggest that being cold can get you sick. Most illnesses are caused by viruses and bacteria. Illnesses like strep throat, influenza, and the common cold are only spread through contact with other infected people. How cold you are when you come into contact with the virus or bacteria has nothing to do with whether or not you will get sick. The effect of body temperature on contracting illness was tested on human beings in the 1950s. Researchers divided volunteers into two groups: half of them were kept in a warm room and the other half were kept in a cold room. Both groups were then exposed to rhinovirus-the virus responsible for the common cold. The researchers discovered that members of both groups developed colds at the same rate. Since that first experiment, there have been similar experiments performed with a variety of different illnesses. All have yielded the same result: being cold does not make a person more likely to get sick. Of course, it does seem that people do get sick more often when the weather is cold. However, this is because there is some evidence that people do get sick more often in cold weather, but it has nothing to do with forgetting to bundle up when it is chilly. When it is cold outside, people tend to stay inside. With so many people gathered closely together indoors, germs are spread more easily. Germs are spread from person to person, regardless of how cold or warm their bodies are. Which word would best replace 'yielded'  in paragraph 2?

Garlic Breath Anyone who has ever had a delicious piece of garlic bread knows that there is a price to pay for eating it: the dreaded garlic breath. What makes garlic so good at making your breath smell so bad? The main culprit is a compound called allyl methyl sulfide. As your body digests the garlic, the sulfide is released into your bloodstream. From there, it travels through your body until it is eliminated through your digestive system, your urine, or out of your pores. However, some of the allyl methyl sulfide also crosses from the bloodstream into the air that fills your lungs. As you breathe this air out, the garlic smell goes with it. This is why no matter how many pieces of gum you chew, how often you brush your teeth, or how much mouthwash you swish, a garlicky meal can give you stinky breath for days. Recent research shows that the best way to combat the effects of garlic on your breath is to eat a raw apple or some raw mint leaves while you consume garlic. Both apples and mint leaves contain polyphenolic compounds that can neutralize the allyl methyl sulfides in garlic. Question: Which word could best replace 'dreaded' in paragraph 1?

Lactose Intolerance Lactose intolerance is the inability to digest a sugar called lactose in milk and other dairy products. Adults in most of the world are lactose intolerant, although infants are not. This is because many adults lack an enzyme known as lactase. Lactase, which can be found in cells in the intestine, is the enzyme that breaks down lactose. Many individuals lose the ability to synthesize lactase after age six. However, not everyone does. Whether or not the body continues to produce lactase often depends on ethnicity. While only 5-15% of adults of European descent cannot digest lactose, 80-90% of adults of African and Asian descent are lactose intolerant. Research has shown that people of northern European ancestry contain a genetic mutation that allows the secretion of lactase in adulthood. The main symptom of lactose intolerance is gastrointestinal upset. Lactose intolerant people may experience diarrhea, bloating, abdominal pain, gas, and vomiting after consuming lactose-containing foods and beverages. Although there has been some research into gene therapy as a treatment for lactose intolerance, the current best treatment is either ingesting lactase supplements when consuming dairy products or simply avoiding foods containing lactose altogether. Question: Which of the following is true according to the passage?

Father of Surgery Abu al-Qasim Khalaf ibn al-Abbas Al-Zahrawi, also known as Albucasis, is considered by many people to be the "Father of Modern Surgery." Al-Zahrawi was born in Spain in 936 CE, a time when Spain was part of the Islamic empire. One of Al-Zahrawi's greatest contributions was the Kitab al-Tasrif, a 30-volume encyclopedia of medical information. The Kitab al-Tasrif took Al-Zahrawi over 50 years to complete. It contains information about a wide variety of illnesses, injuries, medical conditions, treatments, and surgical procedures. His book includes discussions of dentistry, obstetrics, ophthalmology, urology, and cranial surgery, among many others. He even provides illustrations for over 200 different surgical instruments. In the Kitab, Al-Zahrawi presents the first description of an ectopic pregnancy and provides the first evidence that hemophilia is a genetic condition. Surgeons continued to use the information in the Kitab al-Tasrif well into the 1700's. In fact, some of Al-Zahrawi's practices are still being used to this very day. For example, Al-Zahrawi developed a technique to treat gynecomastia (enlarged breast tissue) in men that is still in practice today. Finally, the Kitab also includes something vital for all modern practitioners to keep in mind: a reminder that patients are human beings who must be treated regardless of their wealth or social status. Question: What is the best summary for the passage?

Glowing in the Dark Have you ever wondered how glow-in-the-dark things actually glow in the dark? Most glow-in-the-dark items glow because of something called phosphorescence or photoluminescence. Phosphorescent items must be "charged" under a bright light before they actually glow in the dark. This charging process works because of a substance called phosphor. When light from the sun or a lamp hits phosphor, the phosphor molecules absorb the light and become energized. As the phosphor molecules release the stored energy, they emit a dim light that is visible in the dark. The color of the light that they produce depends on the color of the dye added to the glow-in-the-dark item. Usually, green dye is added to the phosphors to make the light easier to see. Although any color can be used, the human eye sees green light most clearly in the dark. There are also a few glow-in-the-dark items that do not need to be charged. Emergency exit signs, gun sights, and certain kinds of expensive wristwatches glow because of radioluminescence. In these items, the phosphor is mixed with a radioactive element called tritium. The radiation from the tritium provides energy to the phosphor. It is almost as if there are thousands of tiny lamps constantly shining on the phosphor. Because their phosphor is always energized, these radioluminescent items are always glowing. One other kind of glow-in-the-dark item that does not require charging is the glow stick. Glow sticks do not need to be held under light and do not contain any radioactive elements. Instead, glow sticks glow using chemiluminescence. Glow sticks contain a fluorescent dye and a thin glass tube that contains a chemical. To activate a glow stick, you bend the plastic container, causing the glass to break. The chemical inside the glass then mixes with the dye. The combination of the chemical and the dye produces visible light. Question: Which of the following is true according to the passage?

PTSD in Female Veterans Post-traumatic stress disorder (PTSD) is a severe anxiety disorder that affects millions of people around the world. Individuals can develop PTSD after experiencing any event that results in psychological trauma. Symptoms of PTSD involve flashbacks to the traumatic event, nightmares, obsessive behavior, anger, insomnia, difficulty concentrating, and hypervigilance. Individuals who suffer from PTSD can experience significant difficulties in social relationships, have lower self-esteem, and have trouble maintaining employment. People with PTSD experience a higher risk of committing suicide and developing a substance abuse disorder. Although PTSD can affect any individual, military veterans are especially susceptible. Furthermore, within this population, women are more than twice as likely as men to develop PTSD. Although studies investigating precisely why women are more likely than men to experience PTSD have not yet been completed, some experts have theorized that low unit cohesion is a major factor. Unit cohesion, defined as the mutual bonds of friendship and support among members of a military unit, is thought to be helpful in reducing the incidence of developing PTSD. Women are more likely than men to experience low unit cohesion for a variety of reasons. One of the most obvious factors is the relatively lack of females in the military; currently, women make up only 20% of the armed forces. Pervasive male prejudice against women is another factor that can diminish unit cohesion for female soldiers. Perhaps the biggest impediment to achieving quality treatment for women suffering from wartime PTSD is a shortage of research. While both the VA and independent agencies have completed hundreds of studies researching the prevention of and treatment for PTSD amongst general military populations, there have been no studies completed that solely target women. More must be done to help the women who have sacrificed so much for their country. Question: What is the meaning of the word impediment in the last paragraph?