294 research outputs found
Identifying Suspicious Regions of Covid-19 by Abnormality-Sensitive Activation Mapping
This paper presents a fully-automated method for the identification of
suspicious regions of a coronavirus disease (COVID-19) on chest CT volumes. One
major role of chest CT scanning in COVID-19 diagnoses is identification of an
inflammation particular to the disease. This task is generally performed by
radiologists through an interpretation of the CT volumes, however, because of
the heavy workload, an automatic analysis method using a computer is desired.
Most computer-aided diagnosis studies have addressed only a portion of the
elements necessary for the identification. In this work, we realize the
identification method through a classification task by using a 2.5-dimensional
CNN with three-dimensional attention mechanisms. We visualize the suspicious
regions by applying a backpropagation based on positive gradients to
attention-weighted features. We perform experiments on an in-house dataset and
two public datasets to reveal the generalization ability of the proposed
method. The proposed architecture achieved AUCs of over 0.900 for all the
datasets, and mean sensitivity and specificity . The method can also identify notable lesions pointed out in the
radiology report as suspicious regions.Comment: 10 pages, 3 figure
Ca2+-permeable mechanosensitive channels MCA1 and MCA2 mediate cold-induced cytosolic Ca2+ increase and cold tolerance in Arabidopsis
Cold shock triggers an immediate rise in the cytosolic free calcium concentration ([Ca2+]cyt) in Arabidopsis thaliana and this cold-induced elevation of [Ca2+]cyt is inhibited by lanthanum or EGTA. It is suggested that intracellular calcium mainly contributes to the cold-induced [Ca2+]cyt response by entering into the cytosol. Two calcium-permeable mechanosensitive channels, MCA1 and MCA2 (mid1-complementing activity), have been identified in Arabidopsis. Here, we demonstrate that MCA1 and MCA2 are involved in a cold-induced increase in [Ca2+]cyt. The cold-induced [Ca2+]cyt increase in mca1 and mca2 mutants was markedly lower than that in wild types. The mca1 mca2 double mutant exhibited chilling and freezing sensitivity, compared to wild-type plants. Expression of At5g61820, At3g51660, and At4g15490, which are not regulated by the CBF/DREB1s transcription factor, was down-regulated in mca1 mca2. These results suggest that MCA1 and MCA2 are involved in the cold-induced elevation of [Ca2+]cyt, cold tolerance, and CBF/DREB1-independent cold signaling
X-Ray Measured Dynamics of Tycho's Supernova Remnant
We present X-ray proper-motion measurements of the forward shock and
reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of
archival Chandra data taken in 2000, 2003, and 2007. We find that the proper
motion of the edge of the remnant (i.e., the forward shock and protruding
ejecta knots) varies from 0".20 yr^{-1} (expansion index m=0.33, where R = t^m)
to 0".40 yr^{-1} (m=0.65) with azimuthal angle in 2000-2007 measurements, and
0".14 yr^{-1} (m=0.26) to 0".40 yr^{-1} (m=0.65) in 2003-2007 measurements. The
azimuthal variation of the proper motion and the average expansion index of
~0.5 are consistent with those derived from radio observations. We also find
proper motion and expansion index of the reverse-shocked ejecta to be
0".21-0".31 yr^{-1} and 0.43-0.64, respectively. From a comparison of the
measured m-value with Type Ia supernova evolutionary models, we find a
pre-shock ambient density around the remnant of <~0.2 cm^{-3}
Detection and in situ switching of unreversed interfacial antiferromagnetic spins in a perpendicular-exchange-biased system
By using the perpendicular-exchange-biased Pt/Co/α-Cr₂O₃ system, we provide experimental evidence that the unreversed uncompensated Cr spins exist at the Co/α-Cr₂O₃ interface. The unreversed uncompensated Cr spin manifests itself in both the vertical shift of an element-specific magnetization curve and the relative peak intensity of soft-x-ray magnetic circular dichroism spectrum. We also demonstrate an in situ switching of the interfacial Cr spins and correspondingly a reversal of the exchange bias without interfacial atomic diffusion. Such switching shows the direct relationship between the interfacial antiferromagnetic spins and origin of the exchange bias. The demonstrated switching of exchange bias would likely offer a new design of advanced spintronics devices, using the perpendicular-exchange-biased system, with low power consumption and ultrafast operation.Y.Shiratsuchi, H.Noutomi, H.Oikawa, et al. Detection and in situ switching of unreversed interfacial antiferromagnetic spins in a perpendicular-exchange-biased system. Physical Review Letters 109, 077202 (2012); https://doi.org/10.1103/PhysRevLett.109.077202
Neutrino masses and mixing: Singular mass matrices and Quark-lepton symmetry
We suggest an approach to explain the observed pattern of the neutrino masses
and mixing which employs the weakly broken quark-lepton symmetry and does not
require introduction of an ad hoc symmetry of the neutrino sector. The mass
matrices are nearly equal for all quarks and leptons. They have very small
determinants and hierarchical form with expansion parameter lambda = 0.26. The
latter can be realized, e.g., in the model with U(1) family symmetry. The
symmetry is broken at the lambda^2 level. Large lepton mixing appears as a
result of summation of the neutrino and charged lepton rotations which
diagonalize the mass matrices in contrast with quark sector where the up quarks
and down quarks rotations cancel each other. We show that the flip of the sign
of rotation in the lepton sector is a result of the seesaw mechanism which also
enhances the neutrino mixing. In this approach one expects, in general,
deviation of the 2-3 mixing from maximal, s_{13} \sim (1-3) lambda^2,
hierarchical neutrino mass spectrum, and m_{ee} < 10^{-2} eV. The scenario is
consistent with the thermal leptogenesis and (in SUSY context) bounds on lepton
number violating processes, like mu to e gamma.Comment: 25 pages, one figure, ReVTeX4, Nucl. Phys. B versio
Strong evidences of hadron acceleration in Tycho's Supernova Remnant
Very recent gamma-ray observations of G120.1+1.4 (Tycho's) supernova remnant
(SNR) by Fermi-LAT and VERITAS provided new fundamental pieces of information
for understanding particle acceleration and non-thermal emission in SNRs. We
want to outline a coherent description of Tycho's properties in terms of SNR
evolution, shock hydrodynamics and multi-wavelength emission by accounting for
particle acceleration at the forward shock via first order Fermi mechanism. We
adopt here a quick and reliable semi-analytical approach to non-linear
diffusive shock acceleration which includes magnetic field amplification due to
resonant streaming instability and the dynamical backreaction on the shock of
both cosmic rays (CRs) and self-generated magnetic turbulence. We find that
Tycho's forward shock is accelerating protons up to at least 500 TeV,
channelling into CRs about the 10 per cent of its kinetic energy. Moreover, the
CR-induced streaming instability is consistent with all the observational
evidences indicating a very efficient magnetic field amplification (up to ~300
micro Gauss). In such a strong magnetic field the velocity of the Alfv\'en
waves scattering CRs in the upstream is expected to be enhanced and to make
accelerated particles feel an effective compression factor lower than 4, in
turn leading to an energy spectrum steeper than the standard prediction
{\propto} E^-2. This latter effect is crucial to explain the GeV-to-TeV
gamma-ray spectrum as due to the decay of neutral pions produced in nuclear
collisions between accelerated nuclei and the background gas. The
self-consistency of such an hadronic scenario, along with the fact that the
concurrent leptonic mechanism cannot reproduce both the shape and the
normalization of the detected the gamma-ray emission, represents the first
clear and direct radiative evidence that hadron acceleration occurs efficiently
in young Galactic SNRs.Comment: Minor changes. Accepted for publication in Astronomy & Astrophysic
A novel method for determining functional LDL receptor activity in familial hypercholesterolemia: Application of the CD3/CD28 assay in lymphocytes
金沢大学附属病院循環器内科Background: The objective of this study was to develop a new and simple method for measuring low-density lipoprotein receptor (LDLR) activity using peripheral lymphocytes enabling us to clinically diagnose familial hypercholesterolemia (FH) and ascertain the involved mutations (such as K790X mutation), that might not be clearly detected in the conventional method. Methods: Our method comprised the following 2 features: first, we used anti-CD3/CD28 beads to stimulate T-lymphocytes to obtain a uniform fraction of lymphocytes and maximum up-regulation of LDLR. Second, we excluded the possibility of overestimation of lymphocyte signals bound only to its surface, by adding heparin to the cultured lymphocytes used for the LDLR assay. Results: Based on the genetic mutation, the FH subjects were divided into 2 groups, K790X, (n = 20) and P664L, (n = 5), and their LDLR activities was measured by this method, which was found to be 55.3 ± 8.9% and 63.9 ± 13.8%, respectively, of that of the control group (n = 15). In comparison, the LDLR activity was 86.1 ± 11.6% (K790X) and 73.3 ± 6.3% (P664L) of that of the control group when measured by the conventional method, indicating that impairment of LDLR function in FH K790X subjects was much more clearly differentiated with our method than with the conventional method (paired t-test, p < 0.0001). The levels of LDLR expression also showed similar tendencies, that is, 89.4 ± 13.2% (K790X) and 76.9 ± 17.4% (P664L) of that of the control group when measured by the conventional method, and 78.1 ± 9.7% (K790X) and 70.3 ± 26.5% (P664L) when measured by our new method. In addition, we confirmed that there was little influence of statin treatment on LDLR activity among the study subjects when our method was used. Conclusion: These results demonstrate that our new method is applicable for measuring LDLR activity, even in subjects with an internally defective allele, and that T-lymphocytes of the FH K790X mutation possess characteristics of that allele. © 2008 Elsevier B.V. All rights reserved
フクブ ドンテキ ガイショウゴ チハツセイ ニ ショウジタ オウコウ ケッチョウ カンマク レッコウ ヘルニア ノ 1レイ
A 77-year-old woman presented to the emergency department with complains of abdominal pain and frequent vomiting.
In the past, she has never been on surgery but she suffered blunt liver injury after motor vehicle accident nine months ago. She was performed trans-catheter arterial embolization to the left hepatic lobe at that time and had been seeing a doctor regularly for post traumatic biloma.
The contrast-enhanced abdominal CT scan revealed a closed loop and a dilatation of a small intestine. She was diagnosed a small bowel obstruction due to a internal hernia.
She was operated urgently. The surgical exploration showed that the congested jejunum incarcerated into an omental bursa, and an adhesion of the jejunum mesentery and a greater omentum.
We found a mesentery hiatus of the transverse colon, through which a higher jejunum had incarcerated into the omental bursa. The jejunum was reduced manually and the hiatus was closed by suture. The patient followed a favorable postoperative course and was discharged on postoperative day6. We report a extremely rare transverse colon hiatal hernia that occurred in the late onset after blunt abdominal injury with the review of the literature
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