11/08/2011

Radioactivity: Medical Radiation contamination and accidental

We sometimes read in the writings of authors generally unaware of the problems of radiation protection that the radioactivity induced by simple medical imaging, radiation doses well above those induced SONY VGN-FW21E Battery may cross one or the other major nuclear accident .

It turns out that this comparison is risky because it means, usually comparing the radioactive sources "medical" sources and "accidentally", two very different types of radiaoactivite really.

Protection against radiation "ionizing"

This type of Sony VAIO VGN-Z21MN/B battery radiation called "ionizing" because the tissue can ionize electrons from ion-neutral "responsible" electrically extracted. The ionization tends to modify the nuclei of living cells of the human body, which inevitably leads to damage at high doses.

Ionizing radiation is the programming language the most powerful known as "gamma", you are widely used in medical imaging: X-ray radiography simple (gamma) or by injecting a "contrast" radioactive (technetium 99m). The latter radionuclide is very interesting because it uses the wavelength of X-rays, while providing a period of reduced half-life (approximately 6 hours), removing 95% of the product SONY VAIO VGN-FZ21M Battery within 24 hours.

In addition, the doses injected 99mTc imaging is still limited to a minimum for the patient and taking into account the relationship of the study of the benefits / drawbacks, the "turning point" always needs to get the benefit of patients.

The radiation generated by the nuclear industry

They are created by the spread of radioactive elements called "fission products" that are generated in nuclear reactors as a result of the disintegration of the fuel rods (uranium or mixed uranium-plutonium). The amount of ionizing radiation in these reactions are very important, much higher than in medicine, and are basically "trapped" available through the various radiological barriers SONY VAIO VGN-FZ140E Battery to mitigate the maximum variation of the natural environment (air, water).

Thus, the water in the reactors or fuel storage pools, it stops much of the radioactive emissions and simultaneously the operation of cooling and power generation turbines. It is also necessary that the water level covers the entire nuclear fuel. The most serious accidents occur when, for one reason or another, the HP Probook 4710S battery beams are considered more or less long.

The accident in Fukushima in 5 lines

Fukushima's what happens March 11. The loss extended the Acer Aspire 4710 Battery power system primary and backup systems resulted in the shutdown reactor cooling, resulting in a few hours / days of the loss of radioactive barriers and spread large amounts of radiaoctivité in the air and water.

Long-term radioactive and in large quantities

Radionuclides released during the accident, are numerous and the estimated half-life is more important than 6 hours of technetium. Iodine-131 loses half its radioactivity in eight days while the cesium-137 showed a long half-life of 30 and cesium 135, also produced in large quantities in an accident, Acer TravelMate 4000 Battery have lost half their radiaoctivite later. .. 3 million years.

The amount of radionuclides in the air and water as a result of an accident is released phenomenal WHO estimates that a Chernobyl accident led to the 240,000 liquidators identified an average dose of more than 100 mSv, corresponding to approximately 1000 chest radiographs, displaced populations (400,000 people), the HP Pavilion DV1000 battery effect was on average 33 to 50 mSv corresponds to 330-500 chest radiographs.

The problem of radioactive contamination

Finally, it should be noted that in cases of radiological emergency simple example we only irradiation by ionizing particles to speak, are discussed above. In the case of an accident with significant releases of radionuclides into the air and / or water, radiation "simple" problems that may be contaminated with Sony VGP-BPS5 Battery radioactive dust contaminated the human body during inhalation or ingestion of water or food can be complicated.

However, a radioactive particle will not have the same effect if it is the natural barriers, directly into the body where they radiate from within as it were, and n is its impact in direct contact with the various organs of the body " which should be multiplied. When the irradiation is washing and brushing the body in general to get rid of most or all of the dirt particles. If these particles have entered the body, they stay their Sony VGP-BPS2 Battery course, despite all brush and wash "from outside".

High doses of fraud "borders"

If it's like a big nuclear accident in Japan, the dose limits, who can say absolutely reassuring factors were identified by 10 to 20 This clearly shows the inability of authorities to the problem of radioactivity after the accident other that the "fraud" on the relative security that somehow an adjustment variable for the first time much more efficient and less expensive to solve! Most populous country of Japan and a small living room, hp b2000 battery has no alternative except to remove the "normal" conditions of radioactivity is an important part of the country.

In recent years, it is likely that the health consequences of this option is unfortunately very seriously must also remember that the laptop battery accident was not yet in Fukushima, the site is still spewing large doses of radiaoctivité loans - even if they tend to decrease - and that the main problem of the liquid fuel is not well addressed by the authorities.

There are no photos of the "Radio" and the accident

To summarize: on one side (medicine) has a positive (diagnosis), radiation controlled low doses and reduced half-time, on the other side (nuclear industry) irradiation significant and often uncontrolled radionuclide half-life is extremely long and Acer Aspire One Battery can carry more internal contamination very seriously, it would not be appropriate for the final mix of these two problems, if we dare claim to be totally objective?

 

15:36 Publié dans Science | Lien permanent | Commentaires (0)

what's the future of telecommunications

A digital world (I)

Consider recent developments in telecommunications through its use by amateur radio operators, Internet users and mobile phone, try to glimpse their future in the longer term. The prospects are indeed truly fascinating and unexpected ... See Toshiba Satellite A100 battery for yourself!

Today, amateur radio is an activity of more than one million fans worldwide practice. More than three million copies were distributed in 2004. This activity allows the simple scientific curiosity or for not only the communication of short wavelength, but also to study the properties of the ionosphere, new forms of modulation, experiment with new antennas and Toshiba PA3285U-3BRS battery electronic assemblies to be invented.

For over 100 years (see the history of radio amateur on this page) amateur radio is a source of a variety of interests and led to several important discoveries, including of course the short-wave communications and the ionosphere. How far this activity can lead us in the long run?

Today, HP Pavilion DV5 battery none of the major companies involved in the communication are radio frequency (microwave short-wave) is able to imagine the future of telecommunications. The technology associated with this medium at a pace so fast in so many different directions and developed so that it is virtually impossible, its development in a generation ahead. New standards appear to disappear, merge, without waiting for the verdict of the users. Continue to provide under these conditions, the future. One thing is certain. The future of shortwave is tightly coupled with the development of computers, digital communications,Toshiba Satellite A10 battery with the rapid growth of the Internet connected.

The advantage of digital technology lies in a simple treatment of the signal and its insensitivity to disturbances, or is an analog system is very sensitive to the slightest disturbance.

The best evidence of this trend towards "all digital", the exhibition presents the Dayton Hamvention in 2004, the new transceiver Yaesu Vertex FT-DX9000 Toshiba PA3107U-1BRS battery presented below. This transceiver for HF and 6 meters, includes a computer integrated TFT screen and an Internet connection in addition to the traditional I / O (microphone, telegraph key, antenna, serial output, HP, DIN, etc.). The only drawback technology and high performance, is their commitment to the most fortunate among us, without notice, if you sell half your equipmentToshiba PA3399U-1BRS battery because it costs to decide what ... a small car ($ 11,500).

Caught in the Web

Was carried out according to a study by the INSEE in 2004, 70% of French couples with children have computers at home (against 19% in 1998), while the national average was 45%. This proportion is higher in Belgium.

We announced on the Internet? Today in Europe, where almost every second person has a computer Toshiba PA3465U-1BRS battery and where children learn the computer before you know how you fill the internet every day 122 million people, is visited by more than 15 years, about quarter of the population! Internet users connect to it on an average of 16.5 days per month, totaling 24 hours of connection in which they are on the Web pages 2662nd United States, 114 million people connect to it every day.

But all SONY VAIO VGN-AR830E battery users are still stuck in the web. In 2002, approximately 35% of Europeans have Internet access, compared to 44% in Japan and 57% in the United States. According to various statistics, 50.3% of French Internet users to 48.5% of Belgians. This proportion reached 60% in Luxembourg, Switzerland, Germany, Denmark and Norway over 86% in Iceland.

- Nation Master World Internet Usage: To see

If you regularly work with this tool, you know how the Internet can affect your behavior and your work and personal activities. But how far can we go to the Internet? And it makes sense and offers sufficient security, when we expand its applications in all areas? Do not we run the risk of "Taken" this big screen? These are some of the key issues that our society will meet in the near future if we do not want to be some inconvenience and side effects from the use of surprise, no ramp. The Internet is not a trivial technology and hide a few teething SONY VAIO VGN-FW350DH battery problems.

Internet media at the same time, network tool

Since I am involved in information technology since the 80's can try, I step back and analyze what happens to the Internet and try to recognize what we want to avoid in the future, if we use the Web to intense.

Internet is a medium like television or magazines. Although some radio and television over the Internet in streaming audio / video (streaming) are, the Internet is primarily a network, the physical connection of computers HP F4809A battery together.

Internet is also an instrument from a mail system, cats and other ways to open the conference rooms for public discussion and a concentration of knowledge bases accessible through the explorer (browser) and search engines. But not everyone appreciated this new tool. It is not just a subjective feeling of prejudice against new technologies, experienced by some people who are not familiar with computers HP Mini 1000 battery, but the fact is that our representation of the combined company.

You first need some basic computer knowledge to a computer and its various applications (office software, e-mail, chat, databases, etc.) to use.

You need to understand a particular culture, what you read or what you are looking for. This "global culture" in the world does not exist, because it's not on TV. Each national body or company must establish its own rules, traditions and HP Pavilion DV5000 battery customs that are different from those practiced in Europe, Africa, Asia, Pacific and North America or South America. Their culture is unique for your home or your lifestyle, it is difficult to find a common interest in a living example of an Internet lover lost island in the Pacific Ocean and an amateur living in the midst of a major capital Europe or the United States to find, HP Pavilion ZT3000 battery for example.

Finally, the Internet is virtually out of control, he is a victim of its success and prey for hackers, viruses, spam, phishing, ... not to mention pornography. The theme of the subject of this article, we will treat separately.

Read: Internet, for better or for worse

Internet: Communications Media

Internet is now in most areas of life, and many amateurs and professionals can not work without it. In the future, Internet users include well established in our clothing and accessories through flexible interfaces connected by short wave.

The expansion of technology "Voice over IP" (VoIP) is certainly one of the most important trends of the Internet. This environment supports both voice and data services, complemented by new services is not currently available on the traditional telephone network. The environment has an improved bandwidth, so that eventually we can simply in-home services such as video conferencing and use of CRM (customer relationship management), integrated voice services and voice mail and Internet connections.HP 416996-131 battery

Already today, a free program like Skype introduced on the right side you communicate for free with other Skype users around the world. You can also use this program to all calls over the Internet with a phone number for fixed or mobile worldwide for the price of one. Local or substantially all (normally € 0017 € 0.2 per minute for some countries) an average of over 2 million HP Pavilion DV2000 battery users are now permanently connected to the service.

For its part, Microsoft has a solution for years, "MSN Messenger", free calls, text or audio / video with a different user to the MSN client, and can have a webcam with microphone can be installed.

After eating, these tools and found the difference to his phone bill, you can not do without.

In many Western countries, the Internet have cable TV at a price much lower than that of the telephone connection. Personally, I use a satellite connection. These high-tech is completely transparent to the end Asus Eee PC 1005H battery user.

Soon, at your request, you can download to your hard drive favorite local films and radio, using similar technology DivX, MPEG and streaming, and you will be spent only for the actual time watching television credited. This principle is already in force on some TV channels by satellite.

Today, the latest models of computers HP Pavilion ZD7000 come with a TV tuner card and you will soon be transferred easily, data, images, sounds and video from one format to another (eg from the Internet on TV, TV, DVD, DivX, Video camera to the computer, mobile phone to PC, TV or mobile for any other combination).

Test broadband power network (PLC or BPL in English) also suggest that new applications will be available soon through our easy sale. Is it? Not for everyone.

To date, all the justifications courts telecommunications provider, this new type of data have to be checked. But they noted that these tests are available regardless of the rights of the community of ham or other radio spectrum users. The supreme body only HP Pavilion DV9000 battery requires providers "to find a solution" to avoid interference on the HF bands. But so far not reached the interference with the activity levels of amateur radio and other services, including some AM stations. The PLC signal is 28 mV (a signal with an intensity of about S-8) in the amateur bands and broadcast at a radio link is already a signal of only 0.12 mV, or S-1, when the appropriate Dell Inspiron 1525 battery signal very little has been established.

Thus, a United States after an outbreak studies in almost all states had some sellers to back down before the complaints of individuals because of their incompetence filed to reduce interference.

However, attempts to stay elsewhere, including in many European countries, including France, Belgium, Switzerland and Luxembourg to the chagrin of amateur radio and radio stations. The European authorities have this technology, called "Powerline", hoping that soon a Dell Inspiron 5100 battery solution to this problem that all parties are satisfied.

This demonstration of high technology is impressive, even for a lover.

Overall, it is likely that the field of telecommunications, we are offered in the future through the Internet is amazing and hopefully useful to the community that we may be routine tasks as a mouse click or a button to perform a touch screen.

In short, the future of SONY VGP-BPS9A/B battery information technology at the same time a border full of surprises, but unknown and uncertain. I do not want to scare you, it reflects a reality of our post-modern global village. Hope that the future make us smile and always fantastic!

 

14:29 Publié dans Science | Lien permanent | Commentaires (0)

04/08/2011

A brief history of transistors

To begin, we must remember that there are essentially two types of transistors:

- Bipolar transistors consist of a thin layer of doped semiconductor of a type of two zones of opposite type (NSA, for example). The vast majority of transistors as individual components of this family presented.

- The field-effect transistors as small building, SONY VAIO VGN-FZ240E Battery where the gain is a doped semiconductor. By applying a voltage to the properties next frame exchange local semiconductor can operate on the stream. Almost all transistors complex circuits (eg microprocessors) is of this type.

History:

The invention of the transistor effect in a context that has its roots in the early days of radio and telephony. Since 1936, Bell Labs was on us to replace the electromechanical switches for telephone exchanges by static devices more reliable. On the other hand,SONY VAIO VGN-FZ130E/B Battery caused the Second World War, the rapid development of semiconductors (Ge) diodes for the detection of the radar.

The semiconductor materials

The semiconductor materials are gradually being released to radio streams. First galena and copper, selenium, and finally the germanium. These materials were polycrystalline and were used to manufacture sensors and rectifiers. The strange properties of these materials as versatile, the researchers questioned. The SONY VAIO VGN-FZ140E/B Batteryeffects appear extremely semiconductors with the development of techniques for cleaning. He must get into the act with a purity of 10-12 in order to achieve a transistor. The first modern semiconductor materials (silicon doped n-type and P) were produced by S. Ohl, JH. Scaff and HC. Theurer Bell Laboratory in spring 1940 under the direction of WH. Brattain. PN junctions were then made and the manufacturing process for single crystals has been developed for the 1947th theory of semiconductors was developed by the theoretical work of Brilloulin.SONY VAIO VGN-FZ140E Battery

The field effect transistor

The field effect transistor was invented by JE 1925-1928. Lilienfeld. A patent has been filed, but no performance was possible 60 years ago. All researchers involved in the attempts of the saga of the first transistor, such as SONY VAIO VGN-FZ280E Battery triodes component in the solid state (hence the name of the network to the control electrode) to achieve. All these attempts ended in failure. The difficulty came from the state control over the interface between the gate insulator and the semiconductor channel. This problem was effectively resolved by the end of 1959 by MM. Attala, D. and E. Kahng Labate using the thermal oxide of silicon.

I remember a field-effect transistor-ring, called "Tecnetron" (invented by CNET Tezner) in an exhibition at that time.

The bipolar transistor

The bipolar transistor was invented in two stages: The story notes that J. Bardeen and WH. Brattain invented the transistor Climax Bell Lab. This equipment has worked for the first time the 23rd December 1947. It was a device rather rude, slow and unstable. It follows directly switched germanium diodes, SONY VAIO VGN-FZ250E Battery which have long been used to detect radar signals. The story says that researchers conducting a field measurement of potential in a semiconductor with a period (probably understand the behavior of diodes spikes) when presented a better effect if the distance is measured between two points is very low ( a fraction of a mm). In fact, provides the top of the diode corresponds to a small area surrounding the doped contact region. After various manipulations to emphasize that they have come to realize the first transistor with a single crystal of germanium. His statements Sony VAIO VGN-Z21MN/Bwere separated from Gold 5 / 100 mm. Bell Labs made the discovery public in June 1948. The names of the electrodes of the bipolar transistors (base, emitter and collector) is from this moment.

It is worth mentioning that the German researcher Herbert F. Mataré been noticed in 1943 to reduce "interference" between the two points of a dual detector diode to reduce the noise of a radar wave. Hired in France after the war for Westinghouse, he developed a transistor with spikes, Acer Aspire One Battery called transistron in June 1948. This performance, regardless of the work of Bell Labs, was the work of another German Welker, Heinrich, hired by Westinghouse base. He managed to obtain single crystals of germanium in sufficient quality. This device, much more reliable than those of Bell Labs, is patented in August 1948 and in France by the mass production of Westinghouse are made.

The transistor was at the crossroads (théoriquement!) invented a little later, W. Shockley of Bell Lab also attempts since 1936 to a field effect transistor to achieve. This researcher in 1948, combines a patent for a transistor and a junction point that shows the progression of his ideas. He suggested that the principle of crossing the Sony VGP-BPS5 Batterytransistor in 1949. The first prototype was developed by Bell Laboratory in April 1950 (or July 51!) Done. On September 25, 1951 licenses were offered for sale at a price of $ 25,000. The first transistor junctions in the industry, so-called "allies" were produced by two drops of indium on both sides of a thin wafer of germanium crystal. At 600 ° C, widespread in the germanium by a change of this kind of indium. It was released as the two are very close, without touching them. A transistor of this type, known as OC71 was widely marketed by Philips, SONY VAIO VGN-FW21E Battery Mullard, national, Siemens, Valvo ... From the year 1954. The transistor as a glass tube painted black up to 2 cm (with a rounded top) and 5 mm in diameter. With silicone grease in which the transistor was kept filled by his connections. This system was slow and very sensitive to temperature. The performance of this type of transistor is directly related to the thickness of the base. Supporters of the tubes were for these objects, which were then of no interest as curiosities laugh to see! I have a book in support of electronic Elec Sup, 1953, SONY VAIO VGN-FW31M Battery does not even mention these transistors!

Technical developments that led to modern transistors and integrated circuits formed in the late 50:

- Use of silicon in 1954 by Texas Instruments provided a stability much higher temperature

- Technology-MESA (1957 Texas Instruments) and planar (Fairchild 1958), which opens the door for integrated circuits, use.

The industrial use of transistors began, and quickly expanded from the early 60s, leading to a fast pipe.

Integrated circuits

An integrated circuit consists of the union of all components of an assembly on the same silicon wafer.

The first integrated circuit at Texas Instruments, was 12th September 1958 by Jack Kilby. At the same time, Robert Noyce also directed to an integrated circuit at Fairchild. In the early 70's to the first integration of field effect transistors circuits (MOS) in. First metal-gate (PMOS gate aluminum), SONY VAIO VGN-FZ21M Battery which were slow!. This technology was later improved (change in NMOS and CMOS in the early 80s). The speed of the MOS transistors to move to the point that the bipolar transistors has increased significantly in 80 years.

The essential feature of an integrated circuit is the fineness of the design that determines the size of transistors and their connections. In addition, it is smaller, it's fast! Just because the parasitic capacitances HP Pavilion DM4 are smaller. The current size of the smallest of reasons, 65nm, in steady decline. It should be about 25 nm in 2010.

The number of transistors complex circuits exponentially since the early integrated circuits (Moore's law). The complexity of the circuit current reaches 100,000 transistors. It should continue to grow at this pace at least until about 2010.

15:24 Publié dans Science | Lien permanent | Commentaires (0)