352 research outputs found
Molecular Beams
Contains reports on five research projects.Lincoln Laboratory (Purchase Order DDL B-00306)United States Air Force (Contract AF19(604)-7400)United States NavyUnited States Arm
Neonatal mouse gut metabolites influence Cryptosporidium parvum infection in intestinal epithelial cells
The protozoan parasit
Inter-species variation in colour perception
Inter-species variation in colour perception poses a serious problem for the view that colours are mind-independent properties. Given that colour perception varies so drastically across species, which species perceives colours as they really are? In this paper, I argue that all do. Specifically, I argue that members of different species perceive properties that are determinates of different, mutually compatible, determinables. This is an instance of a general selectionist strategy for dealing with cases of perceptual variation. According to selectionist views, objects simultaneously instantiate a plurality of colours, all of them genuinely mind-independent, and subjects select from amongst this plurality which colours they perceive. I contrast selectionist views with relationalist views that deny the mind-independence of colour, and consider some general objections to this strategy
Low-threshold analysis of CDMS shallow-site data
Data taken during the final shallow-site run of the first tower of the
Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with
improved sensitivity to small energy depositions. Four ~224 g germanium and two
~105 g silicon detectors were operated at the Stanford Underground Facility
(SUF) between December 2001 and June 2002, yielding 118 live days of raw
exposure. Three of the germanium and both silicon detectors were analyzed with
a new low-threshold technique, making it possible to lower the germanium and
silicon analysis thresholds down to the actual trigger thresholds of ~1 keV and
~2 keV, respectively. Limits on the spin-independent cross section for weakly
interacting massive particles (WIMPs) to elastically scatter from nuclei based
on these data exclude interesting parameter space for WIMPs with masses below 9
GeV/c^2. Under standard halo assumptions, these data partially exclude
parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT
experiments' data as WIMP signals, and exclude new parameter space for WIMP
masses between 3 GeV/c^2 and 4 GeV/c^2.Comment: 18 pages, 12 figures, 5 table
Exclusion Limits on the WIMP-Nucleon Cross-Section from the First Run of the Cryogenic Dark Matter Search in the Soudan Underground Lab
The Cryogenic Dark Matter Search (CDMS-II) employs low-temperature Ge and Si
detectors to seek Weakly Interacting Massive Particles (WIMPs) via their
elastic scattering interactions with nuclei. Simultaneous measurements of both
ionization and phonon energy provide discrimination against interactions of
background particles. For recoil energies above 10 keV, events due to
background photons are rejected with >99.99% efficiency. Electromagnetic events
very near the detector surface can mimic nuclear recoils because of reduced
charge collection, but these surface events are rejected with >96% efficiency
by using additional information from the phonon pulse shape. Efficient use of
active and passive shielding, combined with the the 2090 m.w.e. overburden at
the experimental site in the Soudan mine, makes the background from neutrons
negligible for this first exposure. All cuts are determined in a blind manner
from in situ calibrations with external radioactive sources without any prior
knowledge of the event distribution in the signal region. Resulting
efficiencies are known to ~10%. A single event with a recoil of 64 keV passes
all of the cuts and is consistent with the expected misidentification rate of
surface-electron recoils. Under the assumptions for a standard dark matter
halo, these data exclude previously unexplored parameter space for both
spin-independent and spin-dependent WIMP-nucleon elastic scattering. The
resulting limit on the spin-independent WIMP-nucleon elastic-scattering
cross-section has a minimum of 4x10^-43 cm^2 at a WIMP mass of 60 GeV/c^2. The
minimum of the limit for the spin-dependent WIMP-neutron elastic-scattering
cross-section is 2x10^-37 cm^2 at a WIMP mass of 50 GeV/c^2.Comment: 37 pages, 42 figure
Exclusion limits on the WIMP-nucleon cross-section from the Cryogenic Dark Matter Search
The Cryogenic Dark Matter Search (CDMS) employs low-temperature Ge and Si
detectors to search for Weakly Interacting Massive Particles (WIMPs) via their
elastic-scattering interactions with nuclei while discriminating against
interactions of background particles. For recoil energies above 10 keV, events
due to background photons are rejected with >99.9% efficiency, and surface
events are rejected with >95% efficiency. The estimate of the background due to
neutrons is based primarily on the observation of multiple-scatter events that
should all be neutrons. Data selection is determined primarily by examining
calibration data and vetoed events. Resulting efficiencies should be accurate
to about 10%. Results of CDMS data from 1998 and 1999 with a relaxed
fiducial-volume cut (resulting in 15.8 kg-days exposure on Ge) are consistent
with an earlier analysis with a more restrictive fiducial-volume cut.
Twenty-three WIMP candidate events are observed, but these events are
consistent with a background from neutrons in all ways tested. Resulting limits
on the spin-independent WIMP-nucleon elastic-scattering cross-section exclude
unexplored parameter space for WIMPs with masses between 10-70 GeV c^{-2}.
These limits border, but do not exclude, parameter space allowed by
supersymmetry models and accelerator constraints. Results are compatible with
some regions reported as allowed at 3-sigma by the annual-modulation
measurement of the DAMA collaboration. However, under the assumptions of
standard WIMP interactions and a standard halo, the results are incompatible
with the DAMA most likely value at >99.9% CL, and are incompatible with the
model-independent annual-modulation signal of DAMA at 99.99% CL in the
asymptotic limit.Comment: 40 pages, 49 figures (4 in color), submitted to Phys. Rev. D;
v.2:clarified conclusions, added content and references based on referee's
and readers' comments; v.3: clarified introductory sections, added figure
based on referee's comment
Labor Mobility Across The Formal/Informal Divide in Turkey: Evidence from Individual Level Data
A population-modulated bibliometric measure with an application in the field of statistics
We use confirmatory factor analysis to derive a unifying measure of
comparison of scientists based on bibliometric measurements, by utilizing the
h-index, some similar h-type indices as well as other common measures of
scientific performance. We use a real data example from nine well-known
departments of statistics to demonstrate our approach and argue that our
combined measure results in a better overall evaluation of a researchers'
scientific work
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