Over $78 billion in prescription and over-the-counter (OTC) drugs are produced each year in the United States alone. Although most people use these medications properly, a significant number do not. They might take them without a doctor’s prescription, use more than prescribed, or take them for reasons other than those that the drugs were prescribed for.
The self-study lessons in this section are written and organised according to the levels of the Common European Framework of Reference for languages (CEFR). There are recordings of different situations and interactive exercises that practise the listening skills you need to do well in your studies, to get ahead at work and to communicate in English in your free time. The speakers you will hear are of different nationalities and the recordings are designed to show how English is being used in the world today.
برنامج Any Audio Converter لتحويل الصوتيات قادر على التعامل مع كافة صيغ الصوت مثل WAV, WMA, OGG, AAC, MP3, M4A, MP2, FLAC والكثير من الصيغ الأخرى. أيضا من أهم ما يُميز البرنامج أنه قادر على تحويل صيغ الفيديو أيضًا وهو ما قد يُغنيك عن استخدام برنامج تحويل الفيديو أيضًا. يحتوي برنامج محول الصوتيات Any Audio Converter على بعض أدوات تحرير وتعديل صيغ الصوت ويحتوي على أداة مهمة لتحميل الفيديوهات أون لاين من مواقع الفيديو المُختلفة.
Laughing gas is available several forms, one being the medical form which is produced to be used as an anaesthetic and is therefore subject to pharmaceuticals law. A second, less pure form of laughing gas is for commercial use and is commonly used to tune engines. This less pure form may often contain other chemicals or gases such as methyl nitrate which can lead to oxygen deficiency in the human body. Laughing gas can also be purchased in cartridges that can be used to make whipped cream.
إذا لاحظنا بعناية الطرق التي يحدث بها الصوت نجد أنه لابد من بذل شغل في كل حالة.الموسيقى يبذل شغلا لتحريك أوتار الآلة الموسيقية كما أن الصوت الناتج عندما تصفق يديك لتشجيع فريقا رياضيا مثلا يأتي من بذل شغل وهذا الشغل المبذول بواسطة اليدين يسبب اضطرابا في الهواء المحيط متحولا إلى طاقة صوتية تتشكل على شكل موجات منتظمة عليه فإن الصوت صورة من صور الطاقة إذا استقبلتها الأذن يحدث الإحساس بالسمع.

Research has shown that stress and anxiety affect nicotine tolerance and dependence. The stress hormone corticosterone reduces the effects of nicotine; therefore, more nicotine must be consumed to achieve the same effect. This increases tolerance to nicotine and leads to increased dependence. Studies in animals have also shown that stress can directly cause relapse to nicotine self-administration after a period of abstinence.
يستخدم الصوت كوسيلة تواصل بين الكائنات الحية، فمثلاً عند الإنسان، يقوم الشخص بإخراج الهواء من الرئتين بكميات معينة وتصطدم أثناء خروجها بالأحبال الصوتية مؤدية إلى اهتزازها وتكوين موجات مختلفة تخرج عن طريق الفم حتى تكون الأحرف المنطوقة، كما يستخدم عند الحيوانات في عمليات التزاوج والنداء والعراك بينها، فارتفاع الصوت يؤدي إلى إحداث حالة الخوف عند الطرف الآخر.
It is no wonder that Duncan, a graduate student at the Massachusetts Institute of Technology, could not quite believe his eyes. To ensure that he had not made a mistake, he quadruple-checked everything within his set-up, ran the experiment again, and took a mental-health break. “I tried to get some sleep, knowing that I wouldn’t be able to tell if the experiment was successful or not for several more hours, but I was finding it pretty difficult to shut down for the night,” he recalls. When Duncan’s alarm went off the next morning, he ran to his computer (still in his pajamas) and crunched the new measurements only to confront the same result: Heat had still moved impossibly fast.
But dramatic improvements in numerical simulations helped to revive the field roughly five years ago—allowing scientists to recognize that the phenomenon might be more widespread. Gang Chen, an engineer at MIT, for example, was able to predict that second sound might be visible within graphite at rather balmy temperatures. That prediction electrified Duncan, who tested it just as soon as he could—eventually putting the rest of his pursuits on the back burner, once the results proved to be so counterintuitive.   
Some fatal accidents have occurred during states of LSD intoxication. Many LSD users experience flashbacks, recurrence of certain aspects of a person’s experience, without the user having taken the drug again. A flashback occurs suddenly, often without warning, and may occur within a few days or more than a year after LSD use. Flashbacks usually occur in people who use hallucinogens chronically or have an underlying personality problem; however, otherwise healthy people who use LSD occasionally may also have flashbacks. Bad trips and flashbacks are only part of the risks of LSD use.
To understand why, just think about how heat is conducted through the air. It is carried via molecules, which constantly collide with each other and scatter the heat in all directions—forwards, sideways and even backwards. That fundamental inefficiency makes conductive heat relatively sluggish (radiant heat, by comparison, can travel at light speed as infrared radiation). The same sluggishness holds for heat moving through a solid. Here, phonons (packets of acoustic vibrational energy) carry the heat much like molecules in the air, allowing it to scatter in all directions and slowly disperse. “It's a little bit like, if you take a drop of food coloring and put it into water, it spreads,” says Keith Nelson, Duncan’s advisor at MIT. “It doesn’t just move straight as an arrow away from where you put the drop.” But that is precisely what Duncan’s experiment suggested. In second sound, the backscattering from phonons is heavily suppressed, allowing heat to shoot forward. “That’s the way wavelike motion behaves,” Nelson says. “If you’re in a pool and you launch a water wave, it will leave where you are.… But it’s just not normal for heat to behave that way.”
– Antitussives and Expectorants – Antitussives are cough suppressants used to treat painful, persistent coughs. Expectorants are used to help clear mucous from the respiratory system. Both medications may contain alcohol and some may contain narcotics, such as codeine, to relieve pain and induce sleep. Some may be addictive. Young people may abuse these medications for the effects derived from alcohol use, as the alcohol content in some OTC preparations may be as high as 40 percent.
يستخدم الصوت كوسيلة تواصل بين الكائنات الحية، فمثلاً عند الإنسان، يقوم الشخص بإخراج الهواء من الرئتين بكميات معينة وتصطدم أثناء خروجها بالأحبال الصوتية مؤدية إلى اهتزازها وتكوين موجات مختلفة تخرج عن طريق الفم حتى تكون الأحرف المنطوقة، كما يستخدم عند الحيوانات في عمليات التزاوج والنداء والعراك بينها، فارتفاع الصوت يؤدي إلى إحداث حالة الخوف عند الطرف الآخر.
Research has shown that stress and anxiety affect nicotine tolerance and dependence. The stress hormone corticosterone reduces the effects of nicotine; therefore, more nicotine must be consumed to achieve the same effect. This increases tolerance to nicotine and leads to increased dependence. Studies in animals have also shown that stress can directly cause relapse to nicotine self-administration after a period of abstinence.
Environmental factors such as the availability of marijuana, expectations about how the drug would affect them, the influence of friends and social contacts, and other factors that differentiate identical twins’ experiences also were found to have an important effect; however, it also was discovered that the twins’ shared or family environment before age 18 had no detectable influence on their response to marijuana.
×