– Aspirin – The most common analgesic used today to treat fever, arthritis and pain; possible side effects can include nausea, heartburn or development of bleeding ulcers. Aspirin prevents stomach upset. Reye’s syndrome may develop if aspirin is given to children with the flu or chicken pox. This disease is characterized by vomiting, swelling of the brain and liver, difficulty with mental functioning, and can often lead to death. People with liver damage should also avoid using aspirin.
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And for the most part, it does not. Second sound was first detected in liquid helium 75 years ago and later seen within three solids. “All indications early on were that this was something that would really be confined to very few materials and only at very low temperatures,” Nelson says. As such, scientists thought they had hit the end of the road. “It wasn’t super clear what [second sound] could be apart from a scientific statement,” says Nicola Marzari, a materials scientist at the Swiss Federal Institute of Technology, in Lausanne, who was not involved in this study. “So, the entire field went dormant for many years.”
علم الصوتيات والذي يُعرف (بالإنجليزية: Phonetics) يختلف عن علم النطقيات أي (Phonology)، حيث يُعنى علم الصوتيات بدراسة العملية التي يتم من خلالها إنتاج الصوت وانتقاله واستقباله من ناحية جسمانية؛ أي انه علم يدرس الأعضاء الحية التي يتم من خلالها إنتاج الصوت (جهاز النطق) وانتقاله (الموجات الصوتية) واستقباله (الاستقبال السمعي). أما علم النطقيات أو الفونولوجيا (كما تُعرف باسم علم الصواتة) فهو يدرس الطبيعة المجرّدة لوحدات الصوت أو الإشارة التي تشكّل الكلمات التي بدورها تشكّل اللغة. وبالتالي يمكن القول أن الصوتيات هي دراسة عملية تكوين الأصوات، أما النطقيات فتتمحور حول دراسة الأصوات في حد ذاتها.
هي الموجات التي تزيد تردداتها على 20 ألف هيرتز والتي تقع خارج نطاق حاسة الاذن البشرية. وهذا النوع من الموجات ما زال موضع بحث واهتمام مكثف نظرا للتطبيقات المهمة التي تمس مجالات عديدة في الصناعة والطب وغيرهما. وقد أصبح بالإمكان إنتاج موجات فوق صوتية تزيد تردداتها على 1.000.000 هيرتز ولا تختلف هذه الموجات من حيث الخواص عن الموجات الصوتية الأخــرى إلا أنه نظرا لقصر طول موجاتها فإنه بالإمكان تنتقل على هيئة أشعة دقيقة عالية الطاقة.
Sound United today announced the commencement of Sound Start, a foundation dedicated to donating 10,000 instruments to children worldwide by the 2020-21 school year. In support of this goal, Sound United is pledging a percentage of Denon, Polk Audio and Definitive Technology sales to the Sound Start foundation. To execute the ambitious goal of 10,000 donated instruments, Sound United partnered with VH1 Save The Music Foundation.
Ryan Duncan froze. He had just performed a new experiment examining common graphite—the stuff of pencil lead—but the results seemed physically impossible: Heat, which typically disperses slowly, had traveled through the graphite at the speed of sound. That is like placing a pot of water on a hot stove and instead of counting down the long minutes until that water starts to simmer, watching it boil almost instantaneously.
Sound United Announces Acquisition of Classé Audio Leading Audio Company Continues to Combine Powerful Brands to Grow Global Scale, Increase Resources and Invest in Innovation Vista, Calif. (January 8, 2018)— Sound United LLC, parent company to Denon®, Marantz®, Polk Audio®, Definitive Technology®, Polk BOOM®, HEOS®, and Boston Acoustics®, today announced it has acquired Classé Audio, a
قدمنا لكم في ثنايا المقالة شرح موجز وبسيط لمجموعة من برامج الأطفال التعليمية بالصوت والصورة ، بالاضافة إلى روابط مباشرة لتحميل برامج تعليمية للأطفال ، وقد تضمنت الفقرات السابقة مجموعة متنوعة من أفضل برامج تعليم الأطفال القراءة والكتابة وهي مناسبة لمرحلة رياض الأطفال وتهدف لاكسابهم أساسيات اللغة العربية والحساب واللغة الانجليزية ، فإن كنت تبحث عن تحميل ألعاب تعليمية للأطفال 5 سنوات أو تحميل ألعاب تعليمية للأطفال 3 سنوات مجانا أو حتى ألعاب تعليمية للأطفال 4 سنوات ، يمكنك الاستفادة من هذه المقالة في ذلك حيث تجد عدة برامج تعليمية مجانية متنوعة تشمل تلقين الطفل عدة مهارات ضرورية باستخدام ألعاب أطفال تعليمية عربية للصغار وبرامج أطفال تعليمية بالصوت والصورة .
Physical effects of cocaine use include constricted peripheral blood vessels, dilated pupils, and increased temperature, heart rate, and blood pressure. The duration of cocaine’s immediate euphoric effects, which include hyper-stimulation, reduced fatigue, and mental clarity, depends on the route of administration. The faster the absorption, the more intense the high.
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.
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.
Sniffing highly concentrated amounts of the chemicals in solvents or aerosol sprays can directly induce heart failure and death. This is especially common from the abuse of fluorocarbons and butane-type gases. High concentrations of inhalants also cause death from suffocation by displacing oxygen in the lungs and then in the central nervous system so that breathing ceases.

Nicotine also is absorbed readily when tobacco is chewed. With regular use of tobacco, levels of nicotine accumulate in the body during the day and persist overnight. Thus, daily smokers or chewers are exposed to the effects of nicotine for 24 hours each day. Nicotine taken in by cigarette or cigar smoking takes only seconds to reach the brain but has a direct effect on the body for up to 30 minutes.


تتألف الموجة الصوتية أو الأمواج الصوتية في أي وسط من حركة اهتزازية حركة اهتزازية سريعة للجزيئات التي تألف الوسط. فحركة إحدى جزيئات الوسط تؤدي إلى اضطراب الجزيئات المجاورة، وهذه بدورها تقوم بنفس العمل، وهكذا دواليك، بحيث أن موجة من الاضطراب تعبر الوسط ابتداء من نقطة الحركة الأولى. وعندما تهتز الشوكة الرنانة في الهواء، فإن حركة الشعبة المهتزة إلى الأمام تضغط الهواء المجاور. إلا أنه سرعان ماتعود هذه المنطقة المنضغطة من الهواء إلى حالتها الاعتيادية بفضل الخاصة المطاطية للهواء وعلى حساب انضغاط المناطق المجاورة، بحيث أن موجة من الضغط الزائد تنتشر ابتداء من الشعبة المهتزة من الشوكة الرنانة، وبنفس الطريقة فإن حركة الشعبة المهتزة إلى الخلف تولد موجة من الضغط الناقص أو التخلخل.
Most users of LSD voluntarily decrease or stop its use over time. LSD is not considered an addictive drug since it does not produce compulsive drug-seeking behaviour as do cocaine, amphetamine, heroin, alcohol, and nicotine. However, like many of the addictive drugs, LSD produces tolerance, so some users who take the drug repeatedly must take progressively higher doses to achieve the state of intoxication that they had previously achieved. This is an extremely dangerous practice, given the unpredictability of the drug.
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.
These are stimulants used primarily to delay the onset of mental and physical fatigue. Students studying long hours for exams, athletes who feel the drugs will improve their performance, and workers who want to stay awake on the job often use stimulants. These drug compounds are often found in diet pills which, if misused, can lead to anorexia nervosa. Anorexia nervosa is a pathological loss of appetite thought to be psychological in origin that is manifested in extreme dieting and excessive thinness. Caffeine is also found in many beverages, pain medications, and allergy and cold remedies.
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