7,772 research outputs found
Self-charging metering and dispensing device for fluids
A self-metering and dispensing device for fluids obtained from a pressurized fluid supply is discussed. Tubing and valving means permit the introduction of fluid into and discharge from a closed cylindrical reservoir. The reservoir contains a slideably disposed piston co-acting with a coil compression spring, with piston travel determining the amount of fluid in the reservoir. Once the determined amount of fluid is introduced into the reservoir, the fluid is discharged by the force of the coil compression spring acting upon the piston
Development of a bedrest muscle stress apparatus
In attempting further to define the deleterious effects of spaceflight on the human body, measurement systems and techniques were devised to determine the loss of skeletal muscle strength and tone as a result of spaceflight exposure. In order to determine how the muscle degradation process progresses with time during nonuse, a system for measuring muscle stress during bedrest was developed. The Bedrest Muscle Stress Apparatus is configured to slip snugly over the foot board of a standard hospital bed. Data collected with this device correlated well with pre- and post-bedrest data collected with the original skeletal muscle stress apparatus
Kaluza-Klein Dark Matter and the Positron Excess
The excess of cosmic positrons observed by the HEAT experiment may be the
result of Kaluza-Klein dark matter annihilating in the galactic halo.
Kaluza-Klein dark matter annihilates dominantly into charged leptons that yield
a large number and hard spectrum of positrons per annihilation. Given a
Kaluza-Klein dark matter particle with a mass in the range of 300-400 GeV, no
exceptional substructure or clumping is needed in the local distribution of
dark matter to generate a positron flux that explains the HEAT observations.
This is in contrast to supersymmetric dark matter that requires unnaturally
large amounts of dark substructure to produce the observed positron excess.
Future astrophysical and collider tests are outlined that will confirm or rule
out this explanation of the HEAT data.Comment: 5 pages, 3 figures, REVTeX
Kaluza-Klein Dark Matter, Electrons and Gamma Ray Telescopes
Kaluza-Klein dark matter particles can annihilate efficiently into
electron-positron pairs, providing a discrete feature (a sharp edge) in the
cosmic spectrum at an energy equal to the particle's mass (typically
several hundred GeV to one TeV). Although this feature is probably beyond the
reach of satellite or balloon-based cosmic ray experiments (those that
distinguish the charge and mass of the primary particle), gamma ray telescopes
may provide an alternative detection method. Designed to observe very
high-energy gamma-rays, ACTs also observe the diffuse flux of electron-induced
electromagnetic showers. The GLAST satellite, designed for gamma ray astronomy,
will also observe any high energy showers (several hundred GeV and above) in
its calorimeter. We show that high-significance detections of an
electron-positron feature from Kaluza-Klein dark matter annihilations are
possible with GLAST, and also with ACTs such as HESS, VERITAS or MAGIC.Comment: 10 pages, 2 figure
Pseudomoduli Dark Matter
We point out that pseudomoduli -- tree-level flat directions that often
accompany dynamical supersymmetry breaking -- can be natural candidates for
TeV-scale dark matter in models of gauge mediation. The idea is general and can
be applied to different dark matter scenarios, including (but not limited to)
those of potential relevance to recent cosmic ray anomalies. We describe the
requirements for a viable model of pseudomoduli dark matter, and we analyze two
example models to illustrate the general mechanism -- one where the
pseudomoduli carry Higgsino-like quantum numbers, and another where they are SM
singlets but are charged under a hidden-sector gauge group.Comment: 20 pages, refs adde
A systematic study of hidden sector dark matter:Application to the gamma-ray and antiproton excesses
Intraocular solitary extramedullary plasmacytoma presenting as unilateral anterior and intermediate uveitis preceded by refractory glaucoma
Background: Solitary extramedullary plasmacytoma (SEP) is a localised proliferation of monoclonal plasma cells involving soft tissue with no or minimal bone marrow involvement and no other systemic evidence of multiple myeloma. Intraocular involvement is exceedingly rare. Case presentation: We report a 78-year-old man who was referred with glaucoma in the right eye. He subsequently developed anterior chamber (AC) inflammation and refractory glaucoma then dense vitritis. A vitrectomy was performed with the biopsy revealing numerous plasma cells with atypical findings. In conjunction with the flow cytometry results, and a systemic work up excluding multiple myeloma, a diagnosis of SEP was made. The patient was treated with ocular external beam radiotherapy with resolution of the intraocular inflammation and control of the intraocular pressure. He remains well with no local recurrence and no development of multiple myeloma over a follow up period of 2.5 years. Conclusions: This is the first case report of SEP presenting as intraocular inflammation without a uveal tract mass
1862-11-17 D.S. Hooper applies for discharge of Noah Hatch
https://digitalmaine.com/cw_me_1st_cav/1400/thumbnail.jp
The Far-infrared Continuum of Quasars
ISO provides a key new far-infrared window through which to observe the
multi-wavelength spectral energy distributions (SEDs) of quasars and active
galactic nuclei (AGN). It allows us, for the first time, to observe a
substantial fraction of the quasar population in the far-IR, and to obtain
simultaneous, multi-wavelength observations from 5--200 microns. With these
data we can study the behavior of the IR continuum in comparison with
expectations from competing thermal and non-thermal models. A key to
determining which mechanism dominates, is the measurement of the peak
wavelength of the emission and the shape of the far-IR--mm turnover. Turnovers
which are steeper than frequency^2.5 indicate thermal dust emission in the
far-IR.
Preliminary results from our ISO data show broad, fairly smooth, IR continuum
emission with far-IR turnovers generally too steep to be explained by
non-thermal synchrotron emission. Assuming thermal emission throughout leads to
a wide inferred temperature range of 50-1000 K. The hotter material, often
called the AGN component, probably originates in dust close to and heated by
the central source, e.g. the ubiquitous molecular torus. The cooler emission is
too strong to be due purely to cool, host galaxy dust, and so indicates either
the presence of a starburst in addition to the AGN or AGN-heated dust covering
a wider range of temperatures than present in the standard, optically thick
torus models.Comment: 4 pages, to be published in the proceedings of "The Universe as Seen
by ISO," ed. M. Kessler. This and related papers can be found at
http://hea-www.harvard.edu/~ehooper/ISOkp/ISOkp.htm
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