15000 bài tập tách từ đề thi thử môn Tiếng Anh có đáp án (Phần 19)

The pain of a migraine headache can virtually disable a person who suffers from it. Millions and millions of people suffer from migraines, although many of them do not even recognize that a migraine is different from a regular headache. A migraine is not at all the same as a normal headache, and it seems to have a very physical cause.

 One symptom of a migraine is a precursor, which is a visual aura before an attack. Yet only about a third of patients actually experience that, and it is therefore not a requirement in the diagnosis. Other symptoms include increased pain when a person moves, nausea, and sensitivity to light and sound. Scientists now believe that migraines are caused, not by abnormal blood vessels as previously believed, but instead by a unique electrical disorder of brain cells. Physicians used to treat migraines with medicine to constrict blood vessels because of the belief that dilated blood vessels were the cause.

 The new research has been enhanced by imaging devices that allow scientists to watch patients' brains during an attack. The results show that sufferers have abnormally excitable neurons, or brain nerve cells. Prior to the attack, the neurons suddenly fire off electrical pulses at the back of the brain, which ripple like waves on a lake after a stone hits the water. They ripple across the top and then the back of the brain, ultimately affecting the brain stem where the pain centers are located. The pain then generates possibly from the brain stem itself or from blood vessels inflamed by the rapidly changing blood flow, or perhaps from both.

 Scientists have experimented by applying a powerful magnet to stimulate the neurons and discovered that some people's brains react differently than others'. When stimulation was applied to the brains of people who had suffered migraines, they saw the initial aura, and some actually suffered migraines. When the same stimulation was applied to the brains of people who had never suffered migraines, they realized no effect and the neurons showed no change.

 Scientists and doctors continue to work on the research in an attempt to find the perfect treatment. It is considered important to treat migraines because it is believed that prolonged untreated attacks could cause physical changes in the brain leading to chronic pain.

 Line Europeans who arrived in the Americas, the first American Indians were immigrants. Because Indians were nomadic hunters and gatherers, they probably arrived in search of new hunting grounds from Asia when they crossed the ice-covered Bering Strait to Alaska. Anthropologists estimate that the entire Indian population north of Mexico was slightly greater than 1,020,000 when the first settlers arrived from Europe. Although Native Americans belonged to one geographic race, their cultures and languages were only marginally similar, and by and large, they had different ways of life. Nomadic migrations required Indians to construct shelters that did not need to be transported, but could be easily erected from the materials found in their new location.

 Eastern Woodland Indian tribes lived in bark-covered wigwams that were shaped like cones or domes. The frame for the hut was made of young trees firmly driven into the ground, and then bent overhead to tie together with bark fibers or strings of animal hides. Sheets and slabs of bark were attached to the frame to construct the roof and walls, leaving an opening to serve as a door and to allow smoke to escape. The Iroquois in north eastern regions built longhouses that were more spacious than wigwams because five to a dozen families lived under one roof. During the winter, they plastered clay to the poles of the frame to protect the inhabitants from wind and rain.

 Pueblo Indians who lived in the southwest portion of the United States in northern Arizona and New Mexico constructed elaborate housing with several stories and many rooms. Each family unit had only one room, and their ancestors dug shelters in the walls of cliffs and canyons. The ground story of a Pueblo dwelling had no doors or windows in order to prevent enemies from entering. The next level was set back the width of one room, and the row of rooms above it was set back once again, giving their houses the appearance of a terrace Pueblos used ladders to climb to the upper levels and pulled them in when all family members returned for the night.

 Indians living in deserts used sandstone and clay as construction materials. Those who lived in the valleys of rivers even made bricks of clay with wood chips to add strength and to prevent the clay from cracking. To make roofs, Pueblos tied logs together to make rafters and laid them across the two outside walls. On top of the rafters, layers of tree branches, sticks, grass, and brush created a solid roof to preclude the water from leaking inside. Pueblo dwellings were dark because windows were often not large enough to allow much light.

The problem of cardiac arrest has become a major problem these days. A lot of patients have acute pain after suffering from a stroke. There are plenty of medicines, surgical methods developed in the field of medicine to treat such cardiac problems. These solutions are time consuming and costly. In the process of rehabilitation, the medicines also have a lot of side effects on the human body and take time to give relief. Therefore, a lot of people go for alternative therapies that help in rehabilitation of patients who suffer from cardiac stroke. The alternative therapies help in relieving pain, stress and make the body healthy and fit through exercise, yoga as well as meditation.

 Those who have the cardiac complaint have to take a good care of their diet. Also, they must look after their regular exercise in order to stay fit and make sure that they do not take undue stress. These are some of the precautions that you need to take while you are in the process of rehabilitation. The cardiac rehabilitation can be carried out at the rehabilitation centers as well as at the residence of the patients. Once the patient learns all the exercise and techniques of meditation and understands what diet he or she should include in their meals as the instructions of the doctor’s and dieticians, then it is possible to accomplish the rehabilitation process at home with little guidance and monitoring. But the best results are seen at the center, where the program is given to a group of patients together.

 The alternative therapies used for cardiac rehabilitation are stress management, physical exercises and diet. Stress management is very much essential in the rehabilitation process because it has a lot of effects on the patient’s body. A lot of relaxation techniques are taught to the patients that helps them in stress management, among them meditation is one of the main focuses.

 The various rehabilitation programs also give you information on how to have a stress free lifestyle. The patients are supported and encouraged to discuss their problems with the counselor or fellow patients. This helps them to vent their feelings and feel comforted. Breathing exercises are also of great help for the patients who are undergoing cardiac rehabilitation.

 In addition to stress management, physical exercises are also given a lot of importance in the rehabilitation program. The patients are asked to perform various forms of physical exercise which are suitable to them depending on their age and the severity of their problems. These activities include activities like walking, jogging, cycling, and some other sports like badminton, tennis etc., to maintain their health and keep their muscles, bones, and body tissues in a good state. Cardio exercise in a gymnasium is also encouraged. This helps in strengthening the muscles and managing weight.

 The diet of these patients also needs to be looked upon very carefully. Such people should stay away from alcohol and tobacco consumption in order to improve their health. Make sure that their meals include plenty of organic foodstuffs as well as fruits and juices. Do not include junk and oily foodstuffs in your diet because they are very difficult to digest. The intake of calories should also be done at required level. It is a significant fact that the patients have to understand and work accordingly.