22,250 research outputs found
Astrometric Detection of Double Gravitational Microlensing Events
If a gravitational microlensing event is caused by a widely separated binary
lens and the source approaches both lens components, the source flux is
successively magnified by the individual lenses: double microlensing events. If
events are observed astrometrically, double lensing events are expected to
occur with an increased frequency due to the long range astrometric effect of
the companion. We find that although the trajectory of the source star image
centroid shifts of an astrometric double lensing event has a distorted shape
from both of the elliptical ones induced by the individual single lens
components, event duplication can be readily identified by the characteristic
loop in the trajectory formed during the source's passage close to the
companion. We determine and compare the probabilities of detecting double
lensing events from both photometric and astrometric lensing observations by
deriving analytic expressions for the relations between binary lensing
parameters to become double lensing events. From this determination, we find
that for a given set of the binary separation and the mass ratio the
astrometric probability is roughly an order higher than the photometric
probability. Therefore, we predict that a significant fraction of events that
will be followed up by using future high precision interferometeric instruments
will be identified as double lensing events.Comment: total 6 pages, including 4 figures and no table, ApJ, submitte
Protein transduction: A novel tool for tissue regeneration
Tissue regeneration in humans is limited and excludes vitals organs like heart and brain. Transformation experiments with oncogenes like T antigen have shown that retrodifferentiation of the respective cells is possible but hard to control. To bypass the risk of cancer formation a protein therapy approach has been developed. The transient delivery of proteins rather than genes could still induce terminallydifferentiated cells to reenter the cell cycle. This approach takes advantage of proteintransducing domains that mediate the transfer of cargo proteins into cells. The goal of this brief review is to outline the basics of protein transduction and to discuss potential applications for tissue regeneration
Blending in Future Space-based Microlensing Surveys
We investigate the effect of blending in future gravitational microlensing
surveys by carrying out simulation of Galactic bulge microlensing events to be
detected from a proposed space-based lensing survey. From this simulation, we
find that the contribution of the flux from background stars to the total
blended flux will be equivalent to that from the lens itself despite the
greatly improved resolution from space observations, implying that
characterizing lenses from the analysis of the blended flux would not be easy.
As a method to isolate events for which most of the blended flux is
attributable to the lens, we propose to use astrometric information of source
star image centroid motion. For the sample of events obtained by imposing a
criterion that the centroid shift should be less than three times of the
astrometric uncertainty among the events for which blending is noticed with
blended light fractions , we estimate that the contamination of
the blended flux by background stars will be less than 20% for most () of the sample events. The expected rate of these events is
events/yr, which is large enough for the statistical analysis of the lens
populations.Comment: total 6 pages, including 5 figures, ApJ, in pres
Mitochondrial Regulators of Synaptic Plasticity in the Ischemic Brain
Synaptic plasticity is a process by which neurons adapt or alter the strength of information transfer, and it is known to play a role in memory formation, learning, and recovery after injury. In this chapter, we describe how ischemic insults alter neuronal intracellular mechanisms and signaling pathways, and we discuss how, after neuronal injury, synaptic plasticity is regulated prior to and during death or rehabilitation and recovery. In addition, recently described regulators of synaptic plasticity will be introduced
Low-amplitude and long-period radial velocity variations in giants HD 3574, 63 Cygni, and HD 216946 (Research Note)
Aims. We study the low-amplitude and long-period variations in evolved stars
using precise radial velocity measurements. Methods. The high-resolution,
fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used from
September 2004 to May 2014 as part of the exoplanet search program at the
Bohyunsan Optical Astronomy Observatory (BOAO). Results. We report the
detection of low-amplitude and long-period orbital radial velocity variations
in three evolved stars, HD 3574, 63 Cyg, and HD 216946. They have periods of
1061, 982, and 1382 days and semi-amplitudes of 376, 742, and 699 m/s,
respectively.Comment: 6 pages, 7 figures, 4 tables, accepted for publisation in Astronomy &
Astrophysic
Adjuvant chemotherapy and survival among patients 70âyears of age and younger with node-negative breast cancer and the 21-gene recurrence score of 26-30
BACKGROUND: The benefits of chemotherapy in node-negative, hormone receptor-positive, and human epidermal growth factor receptor 2 (HER2)-negative breast cancer patients with the 21-gene recurrence score (RS) of 18-30, particularly those with RS 26-30, are not known.
METHODS: Using the Surveillance, Epidemiology, and End Results (SEER) data, we retrospectively identified 29,137 breast cancer patients with the 21-gene RS of 18-30 diagnosed between 2004 and 2015. Mortality risks according to the RS and chemotherapy use were compared by the Kaplan-Meier method and Cox\u27s proportional hazards model.
RESULTS: Among the breast cancer patients with the RS 18-30, 21% of them had RS 26-30. Compared to breast cancer patients with RS 18-25, patients with RS 26-30 had more aggressive tumor characteristics and chemotherapy use and increased risk of breast cancer-specific mortality and overall mortality. In breast cancer patients who were aged â€â70âyears and had RS of 26-30, chemotherapy administration was associated with a 32% lower risk of breast cancer-specific mortality (hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.47-0.99) and a 42% lower risk of overall mortality (HR, 0.58; 95% CI, 0.44-0.76). Survival benefits were most pronounced in breast cancer patients who were younger or had grade III tumor.
CONCLUSIONS: The 21-gene RS of 18-30 showed heterogeneous outcomes, and the RS 26-30 was a significant prognostic factor for an increased risk of mortality. Adjuvant chemotherapy could improve the survival of node-negative, hormone receptor-positive, and HER2-negative breast cancer patients with the 21-gene RS 26-30 and should be considered for patients, especially younger patients or patients with high-grade tumors
Entrainment transition in populations of random frequency oscillators
The entrainment transition of coupled random frequency oscillators is
revisited. The Kuramoto model (global coupling) is shown to exhibit unusual
sample-dependent finite size effects leading to a correlation size exponent
. Simulations of locally coupled oscillators in -dimensions
reveal two types of frequency entrainment: mean-field behavior at , and
aggregation of compact synchronized domains in three and four dimensions. In
the latter case, scaling arguments yield a correlation length exponent
, in good agreement with numerical results.Comment: published versio
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