73 research outputs found
Anderson Localization from Berry-Curvature Interchange in Quantum Anomalous Hall System
We theoretically investigate the localization mechanism of the quantum
anomalous Hall effect (QAHE) in the presence of spin-flip disorders. We show
that the QAHE keeps quantized at weak disorders, then enters a Berry-curvature
mediated metallic phase at moderate disorders, and finally goes into the
Anderson insulating phase at strong disorders. From the phase diagram, we find
that at the charge neutrality point although the QAHE is most robust against
disorders, the corresponding metallic phase is much easier to be localized into
the Anderson insulating phase due to the \textit{interchange} of Berry
curvatures carried respectively by the conduction and valence bands. At the
end, we provide a phenomenological picture related to the topological charges
to better understand the underlying physical origin of the QAHE Anderson
localization.Comment: 6 pages, 4 figure
Label-free timing analysis of modularized nuclear detectors with physics-constrained deep learning
Pulse timing is an important topic in nuclear instrumentation, with
far-reaching applications from high energy physics to radiation imaging. While
high-speed analog-to-digital converters become more and more developed and
accessible, their potential uses and merits in nuclear detector signal
processing are still uncertain, partially due to associated timing algorithms
which are not fully understood and utilized. In this paper, we propose a novel
method based on deep learning for timing analysis of modularized nuclear
detectors without explicit needs of labelling event data. By taking advantage
of the inner time correlation of individual detectors, a label-free loss
function with a specially designed regularizer is formed to supervise the
training of neural networks towards a meaningful and accurate mapping function.
We mathematically demonstrate the existence of the optimal function desired by
the method, and give a systematic algorithm for training and calibration of the
model. The proposed method is validated on two experimental datasets. In the
toy experiment, the neural network model achieves the single-channel time
resolution of 8.8 ps and exhibits robustness against concept drift in the
dataset. In the electromagnetic calorimeter experiment, several neural network
models (FC, CNN and LSTM) are tested to show their conformance to the
underlying physical constraint and to judge their performance against
traditional methods. In total, the proposed method works well in either ideal
or noisy experimental condition and recovers the time information from waveform
samples successfully and precisely.Comment: 25 pages, 10 figure
b-Amyloid impairs the regulation of N-methyl-D-aspartate receptors by glycogen synthase kinase 3
b-amyloid NMDA receptor a b s t r a c t Accumulating evidence suggests that glycogen synthase kinase 3 (GSK-3) is a multifunctional kinase implicated in Alzheimer's disease (AD). However, the synaptic actions of GSK-3 in AD conditions are largely unknown. In this study, we examined the impact of GSK-3 on N-methyl-D-aspartate receptor (NMDAR) channels, the major mediator of synaptic plasticity. Application of GSK-3 inhibitors or knockdown of GSK-3 caused a significant reduction of NMDAR-mediated ionic and synaptic current in cortical neurons, whereas this effect of GSK-3 was impaired in cortical neurons treated with b-amyloid (Ab) or from transgenic mice overexpressing mutant amyloid precursor protein. GSK-3 activity was elevated by Ab, and GSK-3 inhibitors failed to decrease the surface expression of NMDA receptor NR1 (NR1) and NR1/postsynaptic density-95 (PSD-95) interaction in amyloid precursor protein mice, which was associated with the diminished GSK-3 regulation of Rab5 activity that mediates NMDAR internalization. Consequently, GSK-3 inhibitor lost the capability of protecting neurons against N-methyl-Daspartate-induced excitotoxicity in Ab-treated neurons. These results have provided a novel mechanism underlying the involvement of GSK-3 in AD. Published by Elsevier Inc
Linking white matter hyperintensities to regional cortical thinning, amyloid deposition, and synaptic density loss in Alzheimer's disease
Carbon Ion Radiotherapy Induce Metabolic Inhibition After Functional Imaging-Guided Simultaneous Integrated Boost for Prostate Cancer
PurposeAs local recurrence remains a challenge and the advantages of the simultaneous integrated boost (SIB) technique have been validated in photon radiotherapy, we applied the SIB technique to CIRT. The aim was to investigate the metabolomic changes of the CIRT with concurrent androgen deprivation therapy (ADT) in localized prostate cancer (PCa) and the unique metabolic effect of the SIB technique.Material and MethodsThis study enrolled 24 pathologically confirmed PCa patients. All patients went through CIRT with concurrent ADT. The gross target volume (GTV) boost was defined as positive lesions on both 68Ga-PSMA PET/CT and mpMRI images. Urine samples collected before and after CIRT were analyzed by the Q-TOF UPLC-MS/MS system. R platform and MetDNA were used for peak detection and identification. Statistical analysis and metabolic pathway analysis were performed on Metaboanalyst.ResultsThe metabolite profiles were significantly altered after CIRT. The most significantly altered metabolic pathway is PSMA participated alanine, aspartate and glutamate metabolism. Metabolites in this pathway showed a trend to be better suppressed in the SIB group. A total of 11 identified metabolites were significantly discriminative between two groups and all of them were better down-regulated in the SIB group. Meanwhile, among these metabolites, three metabolites in DNA damage and repair related purine metabolism were down-regulated to a greater extent in the SIB group.ConclusionMetabolic dysfunction was one of the typical characteristics of PCa. CIRT with ADT showed a powerful inhibition of PCa metabolism, especially in PSMA participated metabolic pathway. The SIB CIRT showed even better performance on down-regulation of most metabolism than uniform-dose-distribution CIRT. Meanwhile, the SIB CIRT also showed its unique superiority to inhibit purine metabolism. PSMA PET/CT guided SIB CIRT showed its potentials to further benefit PCa patients
A multi band study of the optically dark GRB 051028
Observations were made of the optical afterglow of GRB 051028 with the Lulin
observatory's 1.0 m telescope and the WIDGET robotic telescope system. R band
photometric data points were obtained on 2005 October 28 (UT), or 0.095-0.180
days after the burst. There is a possible plateau in the optical light curve
around 0.1 days after the burst; the light curve resembles optically bright
afterglows (e.g. GRB 041006, GRB 050319, GRB060605) in shape of the light curve
but not in brightness. The brightness of the GRB 051028 afterglow is 3
magnitudes fainter than that of one of the dark events, GRB 020124. Optically
dark GRBs have been attributed to dust extinction within the host galaxy or
high redshift. However, the spectrum analysis of the X-rays implies that there
is no significant absorption by the host galaxy. Furthermore, according to the
model theoretical calculation of the Ly absorption to find the limit of
GRB 051028's redshift, the expected band absorption is not high enough to
explain the darkness of the afterglow. While the present results disfavor
either the high-redshift hypothesis or the high extinction scenario for
optically dark bursts, they are consistent with the possibility that the
brightness of the optical afterglow, intrinsically dark.Comment: 5page, 5 figures, 1 table, accepted for publication in PASJ Letter.
PASJ styl
Testing the External Shock Model of Gamma-Ray Bursts using the Late-Time Simultaneous Optical and X-ray Afterglows
We study the ``normal'' decay phase of the X-ray afterglows of gamma-ray
bursts (GRBs), which follows the shallow decay phase, using the events
simultaneously observed in the R-band. The classical external shock model -- in
which neither the delayed energy injection nor time-dependency of shock
micro-physics is considered -- shows that the decay indices of the X-ray and
R-band light curves, and , obey a certain
relation, and that in particular, should be
larger than -1/4 unless the ambient density increases with the distance from
the central engine. For our selected 14 samples, we have found that 4 events
violate the limit at more than the 3 level, so that a fraction of
events are outliers of the classical external shock model at the ``normal''
decay phase.Comment: Accepted for publication in ApJL. 12 page, 2 figures, 2 table
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