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Choose your speed from a multitude of multiprocessors.

People buying more expensive computers will be bombarded by microprocessor names. Here's what you might run into, along with my take on them:

Pentium III-M: This is an older chip, based on an obsolete desktop chip. It's workable, but there are better choices.

Pentium 4: This is a desktop chip. It's powerful and power-hungry. You won't get much more than two hours on your battery. These run hot, so the laptops have to be big for cooling.

Pentium 4-M: These are less powerful than their desktop brothers. But they are better with batteries, and the computers are not as heavy.

Pentium M: These run slower than the 4's, but they're just about as powerful. This is Intel's newest chip, and, for my money, the best of the Pentiums.

Athlon XP-M: Advanced Micro Devices’ answer to the Pentium. This is a good chip, and it’s usually cheap. Not widely used, but definitely worth considering.

Athlon 64: This is a top of the line chip from AMD. It could run 64-bit software, if any were available. It also runs today’s 32-bit software very well. This chip is extremely fast, but probably no better than its Athlon XP cousin. Don’t pay extra for the 64-bit capability; you can’t use it.

Celeron and Celeron M: The budget chip from Intel. This is not as fast as the Pentiums or the AMD chips.

Transmeta: These are used by a few Japanese manufacturers. Transmeta chips are on the slow side.

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3.3.1. A Long Way to Go

Astronomy is almost certainly the oldest of all the sciences. Since his beginning, man has gazed up at the stars and wondered what they are and why they are there. He has even attempted to discover his destiny by observing them. Although most of early man's ideas about the Universe seem comical nowadays, many ancient civilizations achieved a remarkable understanding of astronomy. They did not only deduce that the Earth revolves round the sun, but also measured the distance between them. In particular, the Greeks made very accurate measurements of the positions and apparent movements of the stars, and the star catalogue produced by Hipparchus in 150 BC was not improved until the 16th century.

The Chinese had also a well-developed knowledge of astronomy. In fact, they made the first observation in a study which is still going on today. In 1054 A.D., they recorded a spectacular cosmic event – the explosion of a star, which became so bright that it could be seen during the day for several months. The remnants of this event form one of the most beautiful and still one of the most studied objects in the sky, the Grab Nebula.

One of the tragedies of astronomy is that after the great discoveries made by many of the ancient civilizations, much of the knowledge seems to have been lost for many centuries. The fact that the earth is round was known to the Greeks, but it took the great voyages of Christopher Columbus in the 15th century to prove it all over again. Even the Greeks didn't get it all right, however. Ptolemy, who, unfortunately, was held in high regard, placed the Earth and not the sun at the center of everything. This, of course, was much more satisfactory for the importance of man and it was not until the 16th century, in fact, that Copernicus proved once and for all that some of the earliest astronomers had been right the first time.



Man had by this time put a great deal of effort into observing the Universe. But the beginnings of modern astronomy really had to wait until the early 17th century, when Galileo built his first small telescope and was able to catch a glimpse of the true depth and mystery of the Universe.

3.3.2. Europe Planning a Mars Rover Mission

European space scientists have strongly recommended a mission equipped with a Rover as the next scientific mission to Mars as part of the European Space Agency’s [ESA] Aurora programme of planetary exploration.

The mission would conduct a detailed analysis of the Martian environment and search for traces of past or present life. A launch in June 2011, followed by a two year journey, would arrive on the Red Planet in June 2013. A detailed proposal will be prepared for consideration by ESA member states at the agency’s Council Meeting at Ministerial Level in December 2005.

The recommendation was made by European scientists at an international space workshop held at Aston University, Birmingham, England on the 6th and 7th April 2005. The ESA workshop, hosted by the UK’s Particle Physics and Astronomy Research Council [PPARC], brought together space scientists and agency officials from Europe, Canada, North America and the international space community in order to debate robotic mission options up to 2013 in the first phase of the Aurora programme.

Three candidate missions were considered: BeagleNet, ExoMars and its variant ExoMars-Lite. Consideration was also given to the preparatory activities needed to develop a sustainable, long-term Mars Exploration programme and how efforts to 2011 address the requirements of a Mars Sample Return [MSR] mission within an overall Aurora roadmap.

Following scientific and technology presentations of each candidate mission an evaluation process was undertaken by the scientists measured against key criteria. The outcome and consensus of the workshop recommended a mission which blended key technologies and objectives from each of the candidate missions as the first robotic mission in the Aurora programme. This recommendation will form the basis of a detailed proposal by the scientific community to be considered at the ESA’s Council Meeting at Ministerial Level in December 2005.

The recommended mission will consist of a Soyuz launcher to deliver a probe which includes at least one Rover for scientific exploration of the Martian environment. Telecommunications [data relay] between the probe and Earth will be achieved via NASA orbiting spacecraft. The Rover would be equipped with a suite of scientific instruments designed to search for traces of past or present life on Mars; to characterise the shallow subsurface water/geochemical composition and its vertical distribution profile; and to identify surface and environmental hazards to future human missions. Taking into account the exciting and scientifically intriguing results from ESA’s Mars Express orbiter the recommended mission will also incorporate instruments to specifically measure seismic phenomena which could be caused by volcanoes, hydrothermal activity or Marsquakes. The Rover will also contain a drill capable of penetrating the surface to a depth of 2m and a Beagle 2 type life marker experiment such as a Gas Analysis Package [GAP] capable of studying stable isotopes in the atmosphere, rocks, and soil. The entry, descent and landing system [EDLS] will utilise key technologies involving airbags and possibly retrorockets. To be launched by a Soyuz Fregat 2b vehicle in June 2011 from ESA’s spaceport at Kourou in French Guiana the probe and Rover would arrive on the surface of Mars in June 2013 after a two year voyage.

Looking beyond 2011 the scientists confirmed their commitment to collaborating in an international Sample Return Mission in 2016 [which would include sample acquisition and handling, mobility and planetary protection], as a logical sequence to the recommended mission in the future roll out of ESA’s Aurora programme.

Commenting on the workshop Prof. Jean Pierre Swings, Chair of ESA’s Exploration Programme Advisory Committee, said,” This workshop has brought an extremely wide range of scientists together from a diverse range of disciplines to recommend what will be a tremendously exciting mission for European space. It builds upon the success of ESA’s Mars Express whilst driving new technologies that will form the foundation for the future development of the Aurora programme”.

In terms of UK involvement Dr. Mark Sims, University of Leicester and Chair of PPARC’s Aurora Advisory Committee was buoyant,” This is a great result for European planetary exploration with significant involvement for the UK. The UK community has worked hard to ensure that the Aurora programme reflects the scientific and industrial expertise we have in the UK and the recommended mission builds upon the heritage of Beagle 2 and Huygens. We look forward to making major contributions to this scientific mission of discovery to the Red Planet”.

3.3.3. How to Watch a Partial Solar Eclipse Safely

Looking at the Sun is harmful to your eyes at any time, partial eclipse or no. The danger that a partial solar eclipse poses is simply that it may prompt people to gaze at the Sun, something they wouldn't normally do. The result can be "eclipse blindness," a serious eye injury that can leave temporary or permanent blurred vision or blind spots at the center of your view. Fortunately, there are many easy ways to watch the show safely.

Pinhole projection. The simplest safe way to view a partial solar eclipse is to watch the Sun's image projected onto a piece of paper. Poke a small hole in an index card with a pencil point, face it toward the Sun, and hold a second card three or four feet behind it in its shadow. The hole will project a small image of the Sun's disk onto the lower card. This image will go through all the phases of the eclipse, just as the real Sun does. Experiment with different size holes. A large hole makes the image bright but fuzzy; a small hole makes it dim but sharp.

For a better view, you can reduce the amount of daylight shining on the viewing card by enclosing it in a long box (right). This lets you use a small pinhole giving a sharp image.

A much better way to do pinhole projection can be arranged at a window indoors. Find a room with a Sun-facing window, turn out any lights, and pull the shades. Arrange for sunlight to enter through a small hole punched in a card near the top of the window. Set up a white piece of paper across the room to catch the Sun's image. Again, experiment with different size holes to get the best, sharpest view. (Of course, don't look through the hole directly at the Sun! Look only at the spot of light that falls on the paper.)

If the Sun is too high in the sky for this, you can direct its image horizontally into the room by setting up a small, high-quality mirror on the sill of an open window. Hold the mirror in place with modeling clay. Tape your card with the hole right onto the mirror. Even at its best, pinhole projection gives only a small image. The throw distance in feet, divided by 9, gives the image diameter in inches. Pretty small!


Date: 2015-12-18; view: 588


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