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Resources: Commerceology
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Observing Earth Satellites
The Earth is surrounded by over 9,000 artificial satellites all launched
into orbit in the past 40 years. Perhaps you have seen one of these objects
as a point of light sailing gracefully across the night sky.
Satellites are best seen about an hour after sunset or before sunrise.
Around these times, a passing satellite will reflect sunlight back to a
ground-based observer in a relatively dark sky. Low Earth orbiting
satellites are not visible throughout the night because at late hours
the Earth's shadow will prevent sunlight from illuminating the satellite.
Satellites often appear as a steady point of light and require a few
minutes to travel across the sky. They will disappear from view when
in the Earth's shadow. Some satellites flash every few seconds, a feature
typical of a tumbling satellite such as a discarded rocket body. Certain
satellites will brighten suddenly, briefly outshine the brightest stars
and planets, and then completely fade from view. Iridium satellites
exhibit this behavior because sunlight reflects strongly off their
large, highly reflective external panels.
No Star Shines Forever
All stars pass through stages defined as birth, life and death. Because
stars live for millions or billions of years, no one can observe the
entire life cycle of a star. Instead astronomers have constructed a
theory of stellar evolution consistent with the laws of physics and
supported by observations.
Square Roots
A square root of a number is a number that you can square to get it, that
is a number that you can multiply by itself to get the number. So 2 is a
square root of 4, because 22=4 and 3 is a square root of 9, because 32=9.
(-2)2 is also 4 and (-3)2 is also 9. Numbers that have square roots always
have two, a positive one and a negative one. But the square root symbol
means only the positive one, so we can have one answer to our problem.
Negative numbers don't have square roots, because when you multiply
numbers with like signs you get positive numbers.
What about a number like 2 or 5 or 10. Do they have square roots?
Are there numbers that you can multiply by themselves to get numbers
like these? Clearly there are no whole numbers that will work, but what
about something involving fractions? It turns out that fractions won't
work either. It turns out that if you can't find a whole number to square
and get a given whole number, no fraction will work either.
Simplifying Exponential Expressions
They work for all exponents, positive or negative, but thinking about why
they work for positive exponents can be very helpful for remembering them.
For the second property think of am as m a's multiplied together and an as
n a's multiplied together and then you can see that when you multiply
these two there are a total of m+n a's multiplied together. For the third
property think of am and an the same way, but imagine the n a's in the
denominator canceling with n of the a's in the numerator, so that what
is left is n taken away from m a's which is m-n a's. For the fourth
property you have n groups of m a's which altogether makes mn a's.
The fifth properties comes from the commutative and associative
properties of multiplication after you write the powers as repeated
multiplication. The sixth properties comes from the fact that when
you multiply fractions you multiply straight across.
Biology Articles
The discovery could pave the way for human hibernation of the kind foreshadowed for astronauts in the 30-year-old film 2001: A Space Odyssey.
Human hibernation would make ultralong-haul space travel feasible, with crews effectively put to sleep for months, or even years, by triggering the hibernation genes that man's distant ancestors used millions of years ago to sleep through hostile winters.
The American army, which has been funding the research, is interested in the concept of inducing protective hibernation in battlefield casualties to keep them alive when medical help is not at hand.
Researchers in Britain are also investigating the role of genes in the mini-hibernation of Siberian hamsters, with the aim of triggering similar genes in humans to help people lose weight.
But the first use of hibernation technology is likely to be in transplant surgery, where donor organs would be preserved on shelves for weeks or months by putting them into a state of deep sleep.
After a five-year project, Matthew Andrews, associate professor of genetics at North Carolina State University has identified two genes - PL and PDK-4 - which appear to mastermind hibernation
Wonders of Science
If attendance figures are anything to go by, the eighth annual Science Week
Ireland is proving a resounding success. Still under way with a handful of
events yet to take place next week, including Galway's science fair,
thousands of students and adults have participated in the talks,
presentations and shows included in this year's mix.
Waterford Institute of Technology has attracted more than 6,000
and Sligo Institute of Technology another 5,000. Events at University
College Cork and the institutes in Carlow and Dundalk brought in another
11,000, mainly primary and secondary students. Thousands more attended
libraries, universities, institutes and other venues that collectively
delivered more than 350 Science Week events.
Physicists Find Strong Evidence for New State of Superconductivity
Is customer service a lost art? Before you answer that question, take a
moment and think about the last few times you have gone shopping or out
to dinner. Okay, now that you have really thought about it, is your answer
any different? Why is it that when we actually DO receive excellent
customer service that it makes such an impression on us that we usually
choose to go back? Why - because the occurrences are so few and far
between!!!
Fighting brain diseases
Recently, Harvard scientists discovered that, at least in mice, the brain
can rally against an all-out attack on brain cells by summoning stem cells
to help repopulate the hard-hit region.
Now the researchers want to determine whether similar stem cell activity
can be orchestrated in diseases like ALS or Parkinson's, in which a
specific group of brain cells dies off. Such a finding would lead toward
an understanding of how to achieve similar results in the human brain,
said Jeffrey Macklis, director of the Massachusetts General
Hospital-Harvard Medical School Center for Nervous System Repair.
Weird science
First the report was leaked and then it was published. The Arctic ice cap
is melting. The cause: human produced greenhouse gas emissions, like those
that come from industrialized nations such as the United States.
And, according to the Arctic Climate Impact Assessment, the cap is
melting faster than previously suspected. If the trend continues, the
report predicts, about half of the sea ice will be gone by the end of
the century.
The Arctic Climate Impact Assessment was the work of more than 300
scientists from eight countries that hold Arctic territory, including
the United States. Four years in the making, it is a carefully prepared
report backed by scores of tests and disks of data. But the Bush
administration doesn’t like it.
It would be one thing if the White House came out and said that it was
not going to endorse the report because its energy policy and economic
recovery initiatives depend on the very thing that the assessment says
will cause us problems in the future. Let it melt. Who cares? Drill and
pollute today. Let the future take care of its self.
New Biological Discoveries through Data Intensive Computing
The field of biology is undergoing a revolution, transformed by
sophisticated technologies from a qualitative, descriptive science to
one that's quantitative and predictive. These technologies are producing
a wealth of biological data that, once collected, analyzed and interpreted
holistically, will form the basis for applications ranging from the
development of cancer treatments to the creation of novel bioremediation
technologies that will help clean up the worst Superfund sites
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