338,094 research outputs found
MRI diagnosis of carpal boss and comparison with radiography
Background: A carpal boss is a potentially painful bony mass in the region of the second or third carpometacarpal joint. The combination of clinical examination and radiography is usually sufficient for the diagnosis.
Purpose: To determine whether magnetic resonance imaging (MRI) examination of the quadrangular joint can assist the diagnosis of persistent pain near a carpal boss.
Material and Methods: Fifty-seven patients with a carpal boss were retrospectively reviewed using MRI and conventional radiographs and compared to an asymptomatic control group.
Results: MRI demonstrated a variable morphology and a variety of bone and soft tissue abnormalities associated with carpal boss. Bone marrow edema around the quadrangular joint shows a significant correlation (Fisher's exact test: P< 0.001) and a positive correlation (Pearson's test r = 0.632, significant at the 0.01 level [two-tailed]) with a painful carpal boss.
Conclusion: MRI offers detailed examination of bone and soft tissue abnormalities associated with a carpal boss. Local bone marrow edema strongly correlates with a painful carpal boss
Thermal resistances of solder-boss/potting compound combinations
Formulas, which can be used as a design tool, are derived to calculate the thermal resistance of solder-boss/potting compound combinations, for different depths of a solder boss, in electronic cordwood modules. Since the solder boss is the heat source, its shape and position will affect the thermal resistance of the surrounding potting compound
Collapse and Fragmentation of Molecular Cloud Cores. X. Magnetic Braking of Prolate and Oblate Cores
The collapse and fragmentation of initially prolate and oblate, magnetic
molecular clouds is calculated in three dimensions with a gravitational,
radiative hydrodynamics code. The code includes magnetic field effects in an
approximate manner: magnetic pressure, tension, braking, and ambipolar
diffusion are all modelled. The parameters varied for both the initially
prolate and oblate clouds are the initial degree of central concentration of
the radial density profile, the initial angular velocity, and the efficiency of
magnetic braking (represented by a factor or ). The
oblate cores all collapse to form rings that might be susceptible to
fragmentation into multiple systems. The outcome of the collapse of the prolate
cores depends strongly on the initial density profile. Prolate cores with
central densities 20 times higher than their boundary densities collapse and
fragment into binary or quadruple systems, whereas cores with central densities
100 times higher collapse to form single protostars embedded in bars. The
inclusion of magnetic braking is able to stifle protostellar fragmentation in
the latter set of models, as when identical models were calculated without
magnetic braking (Boss 2002), those cores fragmented into binary protostars.
These models demonstrate the importance of including magnetic fields in studies
of protostellar collapse and fragmentation, and suggest that even when magnetic
fields are included, fragmentation into binary and multiple systems remains as
a possible outcome of protostellar collapse.Comment: 20 pages, 8 figures. Astrophysical Journal, in pres
Threaded pilot insures cutting tool alignment
Threaded pilot allows machining of a port component, or boss, after the reciprocating hole has been threaded. It is used to align cutting surfaces with the boss threads, thus insuring precision alignment
The SDSS-III Baryon Oscillation Spectroscopic Survey: Quasar Target Selection for Data Release Nine
The SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), a five-year
spectroscopic survey of 10,000 deg^2, achieved first light in late 2009. One of
the key goals of BOSS is to measure the signature of baryon acoustic
oscillations in the distribution of Ly-alpha absorption from the spectra of a
sample of ~150,000 z>2.2 quasars. Along with measuring the angular diameter
distance at z\approx2.5, BOSS will provide the first direct measurement of the
expansion rate of the Universe at z > 2. One of the biggest challenges in
achieving this goal is an efficient target selection algorithm for quasars over
2.2 < z < 3.5, where their colors overlap those of stars. During the first year
of the BOSS survey, quasar target selection methods were developed and tested
to meet the requirement of delivering at least 15 quasars deg^-2 in this
redshift range, out of 40 targets deg^-2. To achieve these surface densities,
the magnitude limit of the quasar targets was set at g <= 22.0 or r<=21.85.
While detection of the BAO signature in the Ly-alpha absorption in quasar
spectra does not require a uniform target selection, many other astrophysical
studies do. We therefore defined a uniformly-selected subsample of 20 targets
deg^-2, for which the selection efficiency is just over 50%. This "CORE"
subsample will be fixed for Years Two through Five of the survey. In this paper
we describe the evolution and implementation of the BOSS quasar target
selection algorithms during the first two years of BOSS operations. We analyze
the spectra obtained during the first year. 11,263 new z>2.2 quasars were
spectroscopically confirmed by BOSS. Our current algorithms select an average
of 15 z > 2.2 quasars deg^-2 from 40 targets deg^-2 using single-epoch SDSS
imaging. Multi-epoch optical data and data at other wavelengths can further
improve the efficiency and completeness of BOSS quasar target selection.
[Abridged]Comment: 33 pages, 26 figures, 12 tables and a whole bunch of quasars.
Submitted to Ap
The Big Occulting Steerable Satellite (BOSS)
Natural (such as lunar) occultations have long been used to study sources on
small angular scales, while coronographs have been used to study high contrast
sources. We propose launching the Big Occulting Steerable Satellite (BOSS), a
large steerable occulting satellite to combine both of these techniques. BOSS
will have several advantages over standard occulting bodies. BOSS would block
all but about 4e-5 of the light at 1 micron in the region of interest around
the star for planet detections. Because the occultation occurs outside the
telescope, scattering inside the telescope does not degrade this performance.
BOSS could be combined with a space telescope at the Earth-Sun L2 point to
yield very long integration times, in excess of 3000 seconds. If placed in
Earth orbit, integration times of 160--1600 seconds can be achieved from most
major telescope sites for objects in over 90% of the sky. Applications for BOSS
include direct imaging of planets around nearby stars. Planets separated by as
little as 0.1--0.25 arcseconds from the star they orbit could be seen down to a
relative intensity as little as 1e-9 around a magnitude 8 (or brighter) star.
Other applications include ultra-high resolution imaging of compound sources,
such as microlensed stars and quasars, down to a resolution as little as 0.1
milliarcseconds.Comment: 25pages, 4 figures, uses aaspp4, rotate, and epsfig. Submitted to the
Astrophysical Journal. For more details see
http://erebus.phys.cwru.edu/~boss
The Stripe 82 Massive Galaxy Project II: Stellar Mass Completeness of Spectroscopic Galaxy Samples from the Baryon Oscillation Spectroscopic Survey
The Baryon Oscillation Spectroscopic Survey (BOSS) has collected spectra for
over one million galaxies at over a volume of 15.3 Gpc (9,376
deg) -- providing us an opportunity to study the most massive galaxy
populations with vanishing sample variance. However, BOSS samples are selected
via complex color cuts that are optimized for cosmology studies, not galaxy
science. In this paper, we supplement BOSS samples with photometric redshifts
from the Stripe 82 Massive Galaxy Catalog and measure the total galaxy stellar
mass function (SMF) at and . With the total SMF in hand,
we characterize the stellar mass completeness of BOSS samples. The
high-redshift CMASS ("constant mass") sample is significantly impacted by mass
incompleteness and is 80% complete at only in
the narrow redshift range . The low redshift LOWZ sample is 80%
complete at for . To construct
mass complete samples at lower masses, spectroscopic samples need to be
significantly supplemented by photometric redshifts. This work will enable
future studies to better utilize the BOSS samples for galaxy-formation science.Comment: 18 pages, 17 figures, 5 table
An integrated approach to courseware
Software engineering is becoming increasingly important as an engineering discipline, and its teaching in universities and other higher education institutions should be of high quality. In this paper we describe a tool (BOSS — the Boss Online Submission System) which aids the education of software engineers. BOSS allows students to submit programming assignments online, and to run black-box tests on their programs prior to submission. Instructors can use BOSS to assist in marking such assignments by allowing submitted programs to be tested against multiple data sets. We describe how BOSS helps in the teaching of specific conceptual aspects of software engineering, and how it addresses some of the practical issues involved in teaching large student numbers in a pedagogically neutral manner
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