![[info]](http://l-stat.livejournal.com/img/userinfo.gif){kind=small}
anyway, I still miss Mohammed very much
It is snowing today, a soft snow.. I went for a walk in it, and it was actually kind of nice.
Lately I feel like I don't know where I am going, but that will change soon. I am sure it is just because of the move and the fact that everything is new.
and i heard from Mohammed... he states that he is hurting as well - and i hope more than anything that he will be happy and doing well
this is what wikipedia says about
Polarization (also polarisation) is a property of waves that describes the orientation of their oscillations. Electromagnetic waves such as light, along with other types of wave, exhibit polarization.
By convention, the polarization of light is described by specifying the direction of the wave's electric field. When light travels in free space, in most cases it propagates as a transverse wave—the polarization is perpendicular to the wave's direction of travel. In this case, the electric field may be oriented in a single direction (linear polarization), or it may rotate as the wave travels (circular or elliptical polarization). In the latter cases, the oscillations can rotate rightward or leftward in the direction of travel, and which of those two rotations is present in a wave is called the wave's chirality or handedness. In general the polarization of an electromagnetic (EM) wave is a complex issue. For instance in a waveguide such as an optical fiber, or for radially polarized beams in free space,[1] the description of the wave's polarization is more complicated, as the fields can have longitudinal as well as transverse components. Such EM waves are either TM or hybrid modes.
For longitudinal waves such as sound waves in fluids, the direction of oscillation is by definition along the direction of travel, so there is no polarization. In a solid medium, however, sound waves can be transverse. In this case, the polarization is associated with the direction of the shear stress in the plane perpendicular to the propagation direction. This is important in seismology.
Polarization is significant in areas of science and technology dealing with wave propagation, such as optics, seismology, telecommunications and radar science. The polarization of light can be measured with a polarimeter.
Jan 8, 2010 1 comment
Beautiful quasiparticles: E8 symmetry has been spotted in a magnet
An unusual form of symmetry known as E8 – which some physicists believe underlies a theory of everything – may have been spotted in a solid material for the first time. Physicists in Germany and the UK claim to have shown that the 8D symmetry group describes the spectrum of spin configurations that emerge when a 1D chain of spins is chilled to near absolute zero and subjected to a specific magnetic field. The experimental work also confirms a long-standing prediction of the spectrum at zero magnetic field.
Symmetry plays a fundamental role in our understanding of the physical world. Perhaps the most intriguing of all is E8 – essentially a fantastically beautiful 8D diamond-like lattice of spheres in which each sphere is surrounded by 240 others. E8 shot to fame in 2007 when the US freelance physicist Garrett Lisi, who has an unlikely day-job as a surfer in Hawaii, posted a paper on the arXiv preprint server suggesting that E8 could underpin a theory of everything by mapping out all known particles and how they interact with each other.
However, E8 had fascinated researchers well before Lisi's paper appeared. In 1988 the Russian physicist Alexander Zamolodchikov showed that E8 symmetry could – under certain conditions – also describe the spectrum of spin excitations that occur in 1D Ising ferromagnets. These are chains of spins in which each spin can only interact with its two nearest neighbours. Below a critical temperature, neighbouring spins tend to align perpendicular to the direction of the chain in one of two directions (up or down).
Quantum fluctuations
If a magnetic field is applied perpendicular to the spins, it will encourage spins to flip spontaneously – or tunnel – between up and down. Such fluctuations can propagate though a material much like a particle and are therefore referred to as quasiparticles. These quantum fluctuations occur even at zero temperature and, if the field is strong enough, ferromagnetism is destroyed in a quantum phase transition.
Now, Radu Coldea of Oxford University and colleagues at the Helmholtz Zentrum Berlin (HZB), the University of Bristol and Rutherford Appleton Laboratory have measured the energies of several of these quasiparticles. They did this by cooling the sample of cobalt niobate to 40 mK and firing neutrons at it to create quasiparticles. When this occurs, the spin and energy of the scattered neutrons change relative to the incident beam by an amount that can be used to calculate the energies of the quasiparticles.
When the experiment was done at zero magnetic field, five quasiparticles were spotted. Their energies are described not by E8, but by a mathematical formula derived three decades ago by Barry McCoy and Tai Tsun Wu. McCoy, who is at Stony Brook University in New York, told physicsworld.com that he was "very impressed with the experiment and most gratified to see that our prediction of 1978 has been experimentally observed".
'Golden ratio'
Coldea and colleagues then repeated their measurements in a magnetic field. As the strength of the field was increased to the quantum critical value of 5.5 T, the ratio of energies of the first two quasiparticles approached 1.618. This number is the "golden ratio" and is precisely what should be measured if the quasiparticles are described by E8 – a prediction that was made more than 20 years ago by Zamolodchikov, now at Rutgers University.
Unfortunately the team was unable to study the system at the quantum critical field – where E8 should emerge – because they could only resolve the lowest energy quasiparticle above about 5 T. Although E8 predicts a total of eight quasiparticles, McCoy believes that it will be very difficult to use neutrons to see the higher energy quasiparticles. This is because their energies overlap a region dominated by continuum scattering involving two or more quasiparticles.
About the author
Hamish Johnston is editor of physicsworld.com
Jan 13, 2010
A bulgeless dwarf galaxy emerges in simulation
It may account for more than 80% of the matter in the universe and provide the "gravitational glue" that keeps galaxies together, but dark matter remains a mystery – despite tantalizing hints obtained by researchers in the US late last year. The current best bet is that it consists of slow-moving (or "cold") particles that do not interact with electromagnetic radiation. Indeed, this "cold dark matter" (CDM) is so abundant that astrophysicists can simply use it to predict the shape of some types of galaxies – completely ignoring the tiny effects of visible matter that makes up the stars.
However, this CDM-only approach has failed spectacularly when it comes to studying "dwarf" galaxies – bodies with less than 10% of the mass of the Milky Way. CDM-only simulations suggest that the central regions of these dwarf galaxies should contain a dark-matter core that gets rapidly denser towards the middle. However, observations reveal no such central cusp but a constant density of dark matter throughout the core. Even worse, CDM-only models also predict that the centres of dwarf galaxies should include a dense bulge of stars, which is not seen in real life either.
Although some astrophysicists see these discrepancies as proof that CDM does not exist, others had suspected that they are the result of ignoring star-formation processes involving visible matter. But confirming the latter has not been easy because it requires a vast amount of computing time. Now, however, a new simulation has been carried out by an international team of astrophysicists that suggests that supernovae – massive stellar explosions – play an important role in the formation of dwarf galaxies. CDM, it appears, is indeed the best way of describing the invisible matter that appears to permeate the universe.
The real thing
Carried out by Chris Brook of the University of Central Lancashire in the UK and colleagues in Switzerland, the US and Canada, the simulation is the first to model not only star formation throughout an entire dwarf galaxy but also the gravitational effects of CDM. It suggests that some of the energy given off by supernovae in the core of a dwarf galaxy causes a wind of visible matter to flow out of the core. This movement of mass is significant enough to pull dark matter away from the core, smoothing out the density and making the simulated galaxy look more like the real thing.
The simulation was carried out using about 250 processors running for about two months. The calculation was then repeated using different initial conditions – which yielded a similar result. According to Brook, supernovae have a significant effect on the evolution of dwarf galaxies – but not galaxies the size of the Milky Way – because the overall gravitational potential energy of a dwarf is small. To confirm this, however, the team would have to simulate larger galaxies to see if the effect went away. This would be a major undertaking because a larger galaxy would require at least ten times the computational resources.
Richard Bower, a cosmologist from the University of Durham in the UK, bills the research as "one of the best papers I have ever seen". He adds that the key to the team's success was its ability to simulate the different phases of hydrogen gas that make up much of the visible matter in a galaxy. "[The result] bodes very well for CDM," says Bower. The work is reported in Nature 463 203.
About the author
Hamish Johnston is editor of physicsworld.com
Katherine Trinidad Jan. 4, 2010
Headquarters, Washington
202-358-1100
katherine.trinidad@nasa.gov
Nicole Cloutier-Lemasters
Johnson Space Center, Houston
281-483-5111
nicole.cloutier-1@nasa.gov
Cheryl Gundy/Ray Villard
Space Telescope Science Institute, Baltimore
410-338-4707/410-338-4514
gundy@stsci.edu/villard@stsci.edu
RELEASE: 10-001
NASA ASTRONAUT JOHN GRUNSFELD, INSTRUMENTAL TO HUBBLE TELESCOPE REPAIR, WILL HELP OVERSEE ITS SCIENCE OPERATIONS
WASHINGTON — NASA astronaut John Grunsfeld, who participated in three spaceflights to service the Hubble Space Telescope, is leaving the agency to become the deputy director of the Space Telescope Science Institute in Baltimore. The institute is the science operations center for Hubble and the James Webb Space Telescope, which is planned for launch in 2014.
"During the past 18 years, John has been a true asset to the agency," said NASA Administrator Charles Bolden, a former astronaut who few on the STS-31 mission that deployed the Hubble. "Some have called him the chief Hubble repairman, but I call him a friend and wish him the best in his new endeavor."
In addition to Grunsfeld's flights to Hubble (STS-103 in Dec. 1999, STS-109 in March 2002, and STS-125 in May 2009), he also served on two other shuttle missions. He performed eight critical spacewalks and logged more than 835 hours in space.
During 2003 and 2004, he was NASA's Chief Scientist at the agency's headquarters in Washington. He helped develop the Vision for Space Exploration, which set NASA on the path for future exploration endeavors.
In accepting the institute position, Grunsfeld said, "This is an incredibly exciting opportunity for me to work at a focal point of top astronomers at the leading edge of scientific inquiry. The team at the Space Telescope Science Institute has a demonstrated record of meeting the high performance challenges of operating the Hubble Space Telescope and preparing for the James Webb Space Telescope. I look forward to working with this excellent team as we continue to explore the mysteries of the universe."
lots of love dad, miss you - in a way we have lost part of him
i am sooo hungry, i will go to eat now, though i haven't eaten much today as
i am trying to lose some weight - trying to lose weight really sucks because
i am having these wonderful cravings and i would love to satisfy them LOL
anyway, i am trying to not get down and keep my spirits lifted high
there is really no reason at all for me to even think of being down anyway
oh well, must go.. life is calling me
i've been looking at some interesting job opportunities
my life is always so open and free it seems.. will i ever put down roots? do i even fricking want to? i would with mohammed in a heart beat if we weren't two worlds apart .. who knows, maybe three worlds apart
but our hearts still feel eachother
About The New Green Economy Conference
Date: January 20-22, 2010
Location: Ronald Reagan Building and
International Trade Center - Washington, DC
The National Council for Science and the Environment (NCSE) welcomes you to the 10th National Conference on Science, Policy, and the Environment: The New Green Economy.
Marking a decade of history, NCSE's signature national conference will engage leading thinkers and doers from a diversity of disciplines, sectors, and perspectives in a structured conversation about the meaning of the green economy and how investment in green education, research and jobs can help solve both the economic and environmental crises.
Welcoming over 1000 attendees, The New Green Economy will bring together leaders in sustainable business, environmental policymakers, civil society, university faculty, students from across the nation, and educated citizens.
john is so sweet
i gave him a heart box of candy today
“Council is extremely pleased and impressed by the way the LHC, the experiments and the computing Grid have operated this year,” said President of Council Torsten Åkesson. “The laboratory set itself an ambitious but realistic programme at its February planning meeting. The fact that all the objectives set back then have been achieved is a ringing endorsement of the step-by-step approach adopted by the CERN management.”
A technical stop is needed to prepare the LHC for higher energy running in 2010. Before the 2009 running period began, all the necessary preparations to run up to a collision energy of 2.36 TeV had been carried out.
i dont mean scared as in frightened of harm
i mean scared as in he is so serious
i am frightened of being hurt
Not as one might slip into a stream,
though it is a stream,
nor as we slide from sleep or into sleep,
but as the breath of a passing animal
unmoors a spore from the lacy frond
is the soul brought out of heaven
It is another buoyancy.
With only the briefest fitfulness
the mote hangs in the vapor above the pond,
the crumb rides at the end of the supple line
on the skin of the river
until the slick fish swallows.
One fish, two fish, how many of God's fish
swam out of the sea?
Muskrat, mud rat, does the toothed water rat
still hunt in the sea?
Night bird, nested bird, who drew the whistling bird
so far from the sea?
Red fox, brown fox, can any hungry silver fox
remember the sea?
it is so sweet a book
