1,088 research outputs found
A multi-band semiclassical model for surface hopping quantum dynamics
In the paper we derive a semiclassical model for surface hopping allowing
quantum dynamical non-adiabatic transition between different potential energy
surfaces in which cases the classical Born-Oppenheimer approximation breaks
down. The model is derived using the Wigner transform and Weyl quantization,
and the central idea is to evolve the entire Wigner matrix rather than just the
diagonal entries as was done previously in the adiabatic case. The off-diagonal
entries of the Wigner matrix suitably describe the non-adiabatic transition,
such as the Berry connection, for avoided crossings. We study the numerical
approximation issues of the model, and then conduct numerical experiments to
validate the model.Comment: 29 pages, 10 figure
Progeny of Germ Line Knockouts of \u3cem\u3eASI2\u3c/em\u3e, a Gene Encoding a Putative Signal Transduction Receptor in \u3cem\u3eTetrahymena Thermophila\u3c/em\u3e, Fail to Make the Transition from Sexual Reproduction to Vegetative Growth
The ciliated protozoan Tetrahymena has two nuclei: a germ line micronucleus and a somatic macronucleus. The transcriptionally active macronucleus has about 50 copies of each chromosome. At sexual reproduction (conjugation), the parental macronucleus is degraded and new macronucleus develops from a mitotic product of the zygotic micronucleus. Development of the macronucleus involves massive genome remodeling, including deletion of about 6000 specific internal eliminated sequences (IES) and multiple rounds of DNA replication. A gene encoding a putative signal transduction receptor, ASI2, (anlagen stage induced 2) is up-regulated during development of the new macronuclei (anlagen). Macronuclear ASI2 is nonessential for vegetative growth. Homozygous ASI2 germ line knockout cells with wild type parental macronuclei proceed through mating but arrest at late macronuclear anlagen development and die before the first post-conjugation fission. IES elimination occurs in these cells. Two rounds of postzygotic DNA replication occur normally in progeny of ASI2 germ line knockouts, but endoreduplication of the macronuclear genome is arrested. The germ line ASI2 null phenotype is rescued in a mating of a knockout strain with wild type cells
MCTNet: A Multi-Scale CNN-Transformer Network for Change Detection in Optical Remote Sensing Images
For the task of change detection (CD) in remote sensing images, deep
convolution neural networks (CNNs)-based methods have recently aggregated
transformer modules to improve the capability of global feature extraction.
However, they suffer degraded CD performance on small changed areas due to the
simple single-scale integration of deep CNNs and transformer modules. To
address this issue, we propose a hybrid network based on multi-scale
CNN-transformer structure, termed MCTNet, where the multi-scale global and
local information are exploited to enhance the robustness of the CD performance
on changed areas with different sizes. Especially, we design the ConvTrans
block to adaptively aggregate global features from transformer modules and
local features from CNN layers, which provides abundant global-local features
with different scales. Experimental results demonstrate that our MCTNet
achieves better detection performance than existing state-of-the-art CD
methods
An Identity Perspective on Online Healthcare Communities
Online healthcare communities often experience high churn rates. Our study investigates this phenomenon by integrating the concepts of social stigma, psychological capital, and social identity. Based on survey data from an online community serving lymphoma patients, we found that 1) users’ positive social identity increased their participation and recommendation intentions through enhanced psychological capital empowered by the online community; 2) stigmatized social identity hampered participation and recommendation intentions through decreased psychological capital; 3) users’ personal identity moderated the mediated impacts of positive and stigmatized social identities on participation and recommendation intentions through psychological capital, and 4) participation intention positively influenced recommendation intention. Our study applied the identity theory with a novel approach and offered insights on the development and management of online healthcare communities for both researchers and practitioners
The Differential Role of Human Cationic Trypsinogen (PRSS1) p.R122H Mutation in Hereditary and Nonhereditary Chronic Pancreatitis: A Systematic Review and Meta-Analysis.
Background:Environmental factors and genetic mutations have been increasingly recognized as risk factors for chronic pancreatitis (CP). The PRSS1 p.R122H mutation was the first discovered to affect hereditary CP, with 80% penetrance. We performed here a systematic review and meta-analysis to evaluate the associations of PRSS1 p.R122H mutation with CP of diverse etiology. Methods:The PubMed, EMBASE, and MEDLINE database were reviewed. The pooled odds ratio (OR) with 95% confidence intervals was used to evaluate the association of p.R122H mutation with CP. Initial analysis was conducted with all etiologies of CP, followed by a subgroup analysis for hereditary and nonhereditary CP, including alcoholic or idiopathic CP. Results:A total of eight case-control studies (1733 cases and 2415 controls) were identified and included. Overall, PRSS1 p.R122H mutation was significantly associated with an increased risk of CP (OR = 4.78[1.13-20.20]). Further analysis showed p.R122H mutation strongly associated with the increased risk of hereditary CP (OR = 65.52[9.09-472.48]) but not with nonhereditary CP, both alcoholic and idiopathic CP. Conclusions:Our study showing the differential role of p.R122H mutation in various etiologies of CP indicates that this complex disorder is likely influenced by multiple genetic factors as well as environmental factors
Terahertz Sources, Detectors, and Transceivers in Silicon Technologies
With active devices lingering on the brink of activity and every passive device and interconnection on chip acting as potential radiator, a paradigm shift from “top-down” to “bottom-up” approach in silicon terahertz (THz) circuit design is clearly evident as we witness orders-of-magnitude improvements of silicon THz circuits in terms of output power, phase noise, and sensitivity since their inception around 2010. That is, the once clear boundary between devices, circuits, and function blocks is getting blurrier as we push the devices toward their limits. And when all else fails to meet the system requirements, which is often the case, a logical step forward is to scale these THz circuits to arrays. This makes a lot of sense in the terahertz region considering the relatively efficient on-chip THz antennas and the reduced size of arrays with half-wavelength pitch. This chapter begins with the derivation of conditions for maximizing power gain of active devices. Discussions of circuit topologies for THz sources, detectors, and transceivers with emphasis on their efficacy and scalability ensue, and this chapter concludes with a brief survey of interface options for channeling THz energy out of the chip
H∞ filter for flexure deformation and lever arm effect compensation in M/S INS integration
ABSTRACTOn ship, especially on large ship, the flexure deformation between Master (M)/Slave (S) Inertial Navigation System (INS) is a key factor which determines the accuracy of the integrated system of M/S INS. In engineering this flexure deformation will be increased with the added ship size. In the M/S INS integrated system, the attitude error between MINS and SINS cannot really reflect the misalignment angle change of SINS due to the flexure deformation. At the same time, the flexure deformation will bring the change of the lever arm size, which further induces the uncertainty of lever arm velocity, resulting in the velocity matching error. To solve this problem, a H∞ algorithm is proposed, in which the attitude and velocity matching error caused by deformation is considered as measurement noise with limited energy, and measurement noise will be restrained by the robustness of H∞ filter. Based on the classical “attitude plus velocity” matching method, the progress of M/S INS information fusion is simulated and compared by using three kinds of schemes, which are known and unknown flexure deformation with standard Kalman filter, and unknown flexure deformation with H∞ filter, respectively. Simulation results indicate that H∞ filter can effectively improve the accuracy of information fusion when flexure deformation is unknown but non-ignorable
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