Adding Depth to X-ray Maps (AStronomy)

3D shapes hold clues to the history of star formation.
Xray photos yield projection of these emissions.
Technique - xray shadowing for adding depth to photos.  Uses
cool, dense clouds of neutral gas as a cosmic range finder,
puts the distance scale on the sray emitting regions.
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Quark Studies put theorists in a spin (particle physics)
Nucleons (protons and neutrons) have 3 valence
quarks in each nucleon, defining its physical properties. but
don't define its spin.  So if the quarks don't provide
the spin, the conundrum was what did provide the spin?

    Spin, a fundamental quantum mechanical property of particles,
can only assume certain fixed values.  Protons and neutrons
have a spin of +1/2 , while quarks can have spins of +1/2
and -1/2.  Results of SMC and other SLAC experiemnt show
quarks contribute 25% of a nucleon's spin.  

  Firing a high energy beam of muons spin polarized,
so all their spins are aligned in one direction into a target of nucleons that
are also spin polarized.  Some are scattered , deflected
from their path .  These differences in scattering 
probabilities are called asymmetries.  Then quantum
theory calculate the spin contributions made by quarks.
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Small clusters hit the big time
New ways to create clusters of atoms on the nanometer
scale are opening the door to quantum dot lasers, single electron transistors,
and a host of other applications.

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Semiconductor Clusters, Nanocrystals, and quantum dots
Current research into semiconductor clusters is focused on
the properties of quantum dots - fragments of semiconductor 
consisting of hundreds to many thousands of atoms - with the bulk
bonding geometry and with surface states eliminated bby enclosure in
a material that has a larger band gap.  Quantum dots exhibit strongly 
size-dependent optical and electrical properties.  The ability to join
the dots into complex assemblies creates many opportunities for 
scientific discovery.

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Magnetic Clusters in Molecular Beams, Metals and Semiconductors
The evolution of magnetic order from the microscopic to the macroscopie
regime may be studied with the use of nanometer-scale clusters.
A variety of new techniques can be employed to control the size of magnetic
clusters from the atomic level.  Molecular beams are used to construct 
and measure the magnetic properties of isolated metallic clusters.  Superparamagnetic metallic
particles embedded in a metal exhibit dramatic field-
dependent changes in electrical conduction, providing
a measure of spin-dependent scattering.  Related efforts in semiconductor
hosts with the use of ion implantation have generated room-temperature
ferromagnetic clusters that can be directly imaged by
magnetic force microscopy.

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Bio-Molecular Dynamics Comes of Age
Molecular dynamics (MD) as a computational technique for
simulating the motion of atoms.  Applied to proteins since
mid70's.  Simulate a system of tens of thousands of
atoms as it evolves over times of nanoseconds. 
  Molecular dynamics can also simulate systems not in
equilibrium.  Motions on a molecular scale are sampled by MD 
(not accessible to experiment).
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a lower limit on the age of the universe
A detailed numerical study designed and conducted to estimate the
absolute age and the uncertainty in age of the oldest globular clusters
in our galaxy, and hence to put a robust lower bound on the age of the universe.
Estimates of the uncertainty range and distribbution in the input parameters of 
stellar evolution codes were used to produce 1000 Monte Carlo realizations
of stellar isochrones, which were used to derive
ages for the 17 oldest globular clusters.  A probability distribution
for the mean age of these systems was derived by incorporating the
observational uncertainties in the measured color-magnitude diagrams for
these systems and the predicted isochrones.  The width of the distribution
resulted from the observational uncertainty in RR Lyrae varaible absolute
magnitudes.  Subdominant contributions came from the choice of the color table
used to translate theoretical luminosities and temperatures to observed magnitudes and colors, as well
as from theoretical uncertainties in heavy element abundances
and mixing length. This 95% confidence limit lower
bound is 12.07x10^9 years. and the median age for the
distribution is 14.56x10^9 years.  These age limits, when compared
with the Hubble age estimate, put powerful constraints on cosmology.

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Were Thick Galactic Disks Made by Levitation?
The thick disk of our galaxy displays kinematic and chemical 
properties that are intermediate between those of the halo and the
thin disk stellar populations.  Not all disk galaxies have a 
thick disk.  A theory of the origins of a thick disk can 
potentially provide insights into the physical state of our galaxy in
its infancy.  Levitation, a process that relies on adiabatic
capture into resonance of stellar orbits in a growing disk,
is presented as a plausible formation mechanism;  a 2:2 resonance between
verticle and epicyclic oscillations drifts to large vertical energies as the disk
grows adiabatically.  Resonant stars levitate several kiloparsecs
above the plane, forming at hick disk whose spatial 
distribbutions, kinematics and ages leaves unique observational
signatures on the sky.   The same process can also produce the 
disk globular cluster system.

--fin