S.M.ARTS

  INTRODUCTION Matter is made up of tiny particles called atoms. Atoms are further made of three fundamental particles or sub – atomic particles called electron, proton and neutron. Earlier Dalton postulated that atom is indivisible i.e. cannot be further divided which proved to be wrong by discovery of sub – atomic particles. Types of Sub - atomic Particles Note - Protons and neutrons are almost of same mass.The mass of proton is approximately 2000 times as that of the electron. Discovery of Sub- atomic Particles (a) Electron (e - ): These negatively charged particles were discovered by J. J. Thomson in 1897. In the experiment, a gas at low pressure was taken in a discharge tube made up of glass. At the ends of the discharge tube two electrodes were placed, connected to a battery for high voltage supply. The electrode connected to the negative end was known as cathode and that to the positive as anode. He then observed a stream of negatively charged particles coming out of

LONDON: The brains of adolescents react more responsively to receiving rewards, according to a study that shows it can make learning easier. "The  adolescent brain  is very sensitive to feedback. That makes adolescence the ideal time to acquire and retain new information," said  Sabine Peters , from the  Leiden University  in the Netherlands. Researchers used a large data set for her research with MRI scans. Over a period of five years, no fewer than 736 brain scans were made of a total of 300 subjects between the ages of 8 and 29. According to Peters, the data set is about ten times larger than that of most comparable studies. In the MRI scanner, the participants had to solve a memory game. During that game, the researchers gave feedback on the participants' performance. The study was published in the journal  Nature Communications . "It showed that adolescents responded keenly to educational feedback," said Peters. "If the adolescent received usef

A nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases in a galaxy. The Persian astronomer, Abd al-Rahman al-Sufi, mentioned a true nebula for the first time in his book, Book of Fixed Stars (964). He said that there was a "little cloud" near the Andromeda galaxy. A nebula is usually made up of hydrogen gas and plasma. It may be the first stage of a star's cycle, but it may also be one of the last stages. Many nebulae or stars form from the gravitational collapse of gas in the interstellar medium or ISM. As the material contracts, massive stars may form in the center, and their ultraviolet radiation ionises the surrounding gas, making it visible at optical wavelengths. The size of these nebulae, known as H II regions, varies depending on the size of the original cloud of gas. These are sites where star formation occurs. The formed stars are sometimes known as a young, loose cluster. Some nebulae are formed as the result of supernova ex

Scientists 'inject' information into monkeys' brains In an experiment with science fiction implications, two neuroscientists say they have managed to introduce information directly into the premotor cortex of monkeys. PHOTO CREDIT: Christoph Hitz/NYT When you drive towards an intersection, the sight of the light turning red will make you step on the brake. This action happens due to a chain of events inside your head. Your eyes relay signals to the visual centres in the back of your brain. After those signals get processed, they travel along a pathway to another region, the premotor cortex, where the brain plans movements. Signalling the brain Now, imagine that you had a device implanted in your brain that could shortcut the pathway and 'inject' information straight into your premotor cortex. That may sound like an outtake from The Matrix. But now two neuroscientists at the University of Rochester, USA say they have managed to introduce information directly into

मेघ आये पाठ का सार इस कविता में मेघों के आने की तुलना सजकर आए प्रवासी अतिथि दामाद) से की है। ग्रामीण संस्कृति में दामाद के आने पर उल्लास का जो वातावरण बनता है , मेघों के आने का वर्णन करते हुए कवि ने उसी उल्लास को दिखाया है। कवि ने मेघों की तुलना सजकर आए अतिथि (दामाद) से करते हुए कहा है कि मेघ शहर से आए अतिथि की भाँति सज-धज कर आए हैं। जिस तरह मेहमान के आने पर गाँव के लड़के-लड़कियाँ भाग कर सबको इसकी सूचना देते हैं, उसी तरह मेघ के आने की सूचना देने के लिए हवा तेज़ गति से बहने लगी है। मेहमान को देखने के लिए जिस तरह लोग खिड़की-दरवाजों से झाँकते हैं, उसी तरह मेघों के दर्शन के लिए भी लोग उत्सुकतापूर्वक खिड़की-दरवाजों से बाहर आकाश की तरफ़ देखने लगे हैं। इस तरह छोटे-बड़े, काले-भूरे-सफेद रंग के मेघ अपने दल-बल के साथ आकाश में ऐसे छा गए हैं मानो कोई शहरी मेहमान सज-धज कर गाँव में आया हो। जिस तरह मेहमान के आने पर गाँव के वृद्ध आगे आकर और हाथ जोड़कर अतिथि का आदर सत्कार करते हैं तथा पत्नी दीवार की ओट लेकर देखती हैं उसी तरह आकाश में बादलों के छा जाने पर आँधी चली जिससे बूढ़े पीपेल के पेड़ की डालियाँ झुकन