115 research outputs found
Identification of Bright Lenses from the Astrometric Observations of Gravitational Microlensing Events
When a source star is gravitationally microlensed by a dark lens, the
centroid of the source star image is displaced relative to the position of the
unlensed source star with an elliptical trajectory. Recently, routine
astrometric follow-up measurements of these source star image centroid shifts
by using high precision interferometers are proposed to measure the lens proper
motion which can resolve the lens parameter degeneracy in the photometrically
determined Einstein time scale. When an event is caused by a bright lens, on
the other hand, the astrometric shift is affected by the light from the lens,
but one cannot identify the existence of the bright lens from the observed
trajectory because the resulting trajectory of the bright lens event is also an
ellipse. As results, lensing parameters determined from the trajectory differ
from those of a dark lens event, causing wrong identification of lens
population. In this paper, we show that although the shape and size of the
astrometric centroid shift trajectory are changed due to the bright lens, the
angular speed of centroid shifts around the apparent position of the unlensed
source star is not affected by the lens brightness. Then, one can identify the
existence of the bright lens and determine its brightness by comparing the lens
parameters determined from the angular speed curve with those determined from
the trajectory of observed centroid shifts. Once the lens brightness is
determined, one can correct for the lens proper motion. Since the proposed
method provides both information about the lens brightness (dark or bright) and
the corrected values of the physical parameters of the lens, one can
significantly better constrain the nature of MACHOs.Comment: total 5 pages, including 3 Figures and no Table, accepted to MNRA
Depolarized Holography with Polarization-multiplexing Metasurface
The evolution of computer-generated holography (CGH) algorithms has prompted
significant improvements in the performances of holographic displays.
Nonetheless, they start to encounter a limited degree of freedom in CGH
optimization and physical constraints stemming from the coherent nature of
holograms. To surpass the physical limitations, we consider polarization as a
new degree of freedom by utilizing a novel optical platform called metasurface.
Polarization-multiplexing metasurfaces enable incoherent-like behavior in
holographic displays due to the mutual incoherence of orthogonal polarization
states. We leverage this unique characteristic of a metasurface by integrating
it into a holographic display and exploiting polarization diversity to bring an
additional degree of freedom for CGH algorithms. To minimize the speckle noise
while maximizing the image quality, we devise a fully differentiable
optimization pipeline by taking into account the metasurface proxy model,
thereby jointly optimizing spatial light modulator phase patterns and geometric
parameters of metasurface nanostructures. We evaluate the metasurface-enabled
depolarized holography through simulations and experiments, demonstrating its
ability to reduce speckle noise and enhance image quality.Comment: 15 pages, 13 figures, to be published in SIGGRAPH Asia 202
Case report: Primary chronic calcaneal bursitis treated with subtotal bursectomy in a cat.
A 6-year-old, female spayed Bengal cat with a bodyweight of 6.4 kg was presented with swelling of the bilateral calcaneal region and weight-bearing hindlimb lameness with a 4-month history of unsuccessful conservative therapy. On orthopedic examination, a cyst-like mass around the calcaneal tendon was palpated. Palpating the mass and flexing the tarsal joint triggered pain. Through ultrasonography and magnetic resonance imaging, an inflamed or fluid-accumulated lesion was suspected around the calcaneal tendon, but there was no evidence of calcaneal tendonitis. Swollen calcaneal bursae were removed surgically. Histopathologic examination revealed fibrosis and an edematous feature. The cat was diagnosed with bilateral chronic primary calcaneal bursitis based on history, clinical signs, and diagnostic results. Hence, subtotal bursectomy was performed. At 4 weeks postoperatively, the cat had no pain around the tarsal joints and was ambulating normally. Radiographic and ultrasonographic exams revealed no recurrence of swelling or inflammation in the calcaneal region. Thirteen-month follow-up confirmed acceptable function and no relapse of clinical signs. The inflammation of calcaneal bursa alone can be the primary cause of hindlimb lameness in cats. A cat with hindlimb lameness and swelling on the calcaneal region should be assessed with the possibility of primary calcaneal bursitis. Subtotal calcaneal bursectomy can be considered as an effective treatment for primary chronic bursitis
Effectiveness of Electrical Heating for Improved Thermal Insulation of a Multi-layered Winter Clothing System
This paper investigated the impact of the distance of the heating unit from the body in a multi-layered winter clothing system on effective thermal insulation and heating efficiency. To identify changes in the thermal insulation and heating efficiency of electrical heating in different layers inside a winter clothing ensemble, a series of thermal manikin tests was conducted. A multi-layered winter ensemble with and without activation of a heating unit was tested on the thermal manikin under two different ambient temperature conditions (10°C and 5°C). Results show that the effective thermal insulation of test ensembles increased by 5-7 percent with the activation of the heating unit compared to that without the activation. The closer the heating unit to the body, the higher the effective thermal insulation was in both ambient temperature conditions. This trend was more significant at lower ambient temperature
Novel transforaminal approach allows surgical decompression of an atlantoaxial band in dogs: a cadaveric study and clinical cases.
OBJECTIVES
To describe a novel transforaminal approach for surgical excision of the atlantoaxial (AA) band and examine its feasibility, safety, and mechanical advantages in an ex vivo study and clinical cases.
SAMPLES
26 canine cadavers and 2 canine patients with AA bands.
PROCEDURES
The transforaminal approach via the first intervertebral foramen was designed to avoid damaging the dorsal AA ligament (DAAL) and dorsal laminas to maintain joint stability. The cadaveric study started on December 2020 and lasted 3 months. The ligamentum flavum (LF) was removed using a novel approach; then, gross examination was conducted to verify the potential damage to the spinal cord and associated structures and the adequacy of LF removal. Subsequently, the ex vivo tension test of the DAAL was conducted to establish whether the approach induced mechanical damage to the ligaments. Finally, 2 dogs diagnosed with an AA band were surgically treated with the transforaminal approach.
RESULTS
In the cadaveric study, postsurgical evaluation verified the subtotal removal of LF without damage to the dura mater. There were no significant differences in the mechanical properties of the DAAL, including the ultimate strength (P = .645) and displacement (P = .855), between the surgical and intact groups during the ex vivo tension test. In clinical cases, clinical signs and neurologic grades improved until the final follow-up.
CLINICAL RELEVANCE
The described surgical procedure using a transforaminal approach appears to sufficiently permit the removal of an AA band while reducing damage to the DAAL and spinal cord. Our study highlights the feasibility of the transforaminal approach
Facile Synthesis of Porous Silicon Nanofibers by Magnesium Reduction for Application in Lithium Ion Batteries
We report a facile fabrication of porous silicon nanofibers by a simple three-stage procedure. Polymer/silicon precursor composite nanofibers are first fabricated by electrospinning, a water-based spinning dope, which undergoes subsequent heat treatment and then reduction using magnesium to be converted into porous silicon nanofibers. The porous silicon nanofibers are coated with a graphene by using a plasma-enhanced chemical vapor deposition for use as an anode material of lithium ion batteries. The porous silicon nanofibers can be mass-produced by a simple and solvent-free method, which uses an environmental-friendly polymer solution. The graphene-coated silicon nanofibers show an improved cycling performance of a capacity retention than the pure silicon nanofibers due to the suppression of the volume change and the increase of electric conductivity by the graphene.Korea Institute of Energy Technology Evaluation and Planning (Human Resources Development Program Grant 20144030200600
Observational Evidence for the Effect of Amplification Bias in Gravitational Microlensing Experiments
Recently Alard\markcite{alard1996} proposed to detect the shift of a star's
image centroid, , as a method to identify the lensed source among
blended stars. Goldberg & Wo\'zniak\markcite{goldberg1997} actually applied
this method to the OGLE-1 database and found that 7 out of 15 events showed
significant centroid shifts of arcsec. The amount of
centroid shift has been estimated theoretically by
Goldberg.\markcite{goldberg1997} However, he treated the problem in general and
did not apply it to a particular survey or field, and thus based his estimates
on simple toy model luminosity functions (i.e., power laws). In this paper, we
construct the expected distribution of for Galactic bulge events by
using the precise stellar LF observed by Holtzman et al.\markcite{holtzman1998}
using HST. Their LF is complete up to (),
corresponding to faint M-type stars. In our analysis we find that regular
blending cannot produce a large fraction of events with measurable centroid
shifts. By contrast, a significant fraction of events would have measurable
centroid shifts if they are affected by amplification-bias blending. Therefore,
Goldberg & Wo\'zniak's measurements of large centroid shifts for a large
fraction of microlensing events confirms the prediction of Han and Alard that a
large fraction of Galactic bulge events are affected by amplification-bias
blending.Comment: total 15 pages, including 6 figures, and no Table, submitted to ApJ
on Apr 26 1998, email [email protected]
Effects of stress, depression, and spousal and familial support on maternal identity in pregnant women
Purpose The objective of this study was to identify the factors influencing maternal identity in pregnant women. Methods Using a descriptive research design, a cross-sectional survey was conducted. In total, 127 pregnant women were recruited from a tertiary hospital in Korea from January to April 2019. Measurements included maternal identity, stress, depression, spousal and familial support, and demographic and obstetric characteristics. Data were analyzed by descriptive statistics, the independent t-test, one-way ANOVA, Pearson correlation coefficients, and stepwise multiple regression using SPSS version 25.0. Results The mean score for maternal identity was 131.15 out of 160, and the mean scores for stress, depression, and spousal and familial support were 14.59 (out of 40), 6.82 (out of 30), and 109.04 (out of 132), respectively. Stress (r=–.38, p<.001), depression (r=–.37, p<.001), and spousal and familial support (r=.37, p<.001) were significantly correlated with maternal identity. In multiple regression analysis, stress (β=–0.27, p=.005) and spousal and familial support (β=0.23, p=.014) were found to be significant factors influencing maternal identity in pregnant women (F=14.19, p<.001). Conclusion It is necessary to develop effective strategies to mitigate stress and to encourage spousal and familial support in pregnant women. Such strategies could further enable pregnant women to enhance their maternal identity
Benserazide, the first allosteric inhibitor of Coxsackievirus B3 3C protease
AbstractCoxsackievirus B3 is the main cause of human viral myocarditis and cardiomyopathy. Virally encoded Coxsackievirus 3C protease (3Cpro) plays an essential role in viral proliferation. Here, benserazide was discovered as a novel inhibitor from a drug library screen targeting Coxsackievirus 3Cpro using a FRET-based enzyme assay. Benserazide, whose chemical structure has no electrophilic functional groups, was characterized as a non-competitive inhibitor by enzyme kinetic studies. A molecular docking study with benserazide and its analogs indicated that a novel putative allosteric binding site was involved. Specifically, a 2,3,4-trihydroxybenzyl moiety was determined to be a key pharmacophore for the enzyme’s inhibitory activity. We suggest that the putative allosteric binding site may be a novel target for future therapeutic strategies
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