4,710 research outputs found

    Relation Between Quantum Speed Limits And Metrics On U(n)

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    Recently, Chau [Quant. Inform. & Comp. 11, 721 (2011)] found a family of metrics and pseudo-metrics on nn-dimensional unitary operators that can be interpreted as the minimum resources (given by certain tight quantum speed limit bounds) needed to transform one unitary operator to another. This result is closely related to the weighted â„“1\ell^1-norm on Rn{\mathbb R}^n. Here we generalize this finding by showing that every weighted â„“p\ell^p-norm on Rn{\mathbb R}^n with 1\le p \le \limitingp induces a metric and a pseudo-metric on nn-dimensional unitary operators with quantum information-theoretic meanings related to certain tight quantum speed limit bounds. Besides, we investigate how far the correspondence between the existence of metrics and pseudo-metrics of this type and the quantum speed limits can go.Comment: minor amendments, 6 pages, to appear in J.Phys.

    Landau Transport equations in slave-boson mean-field theory of t-J model

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    In this paper we generalize slave-boson mean-field theory for t−Jt-J model to the time-dependent regime, and derive transport equations for t−Jt-J model, both in the normal and superconducting states. By eliminating the boson and constraint fields exactly in the equations of motion we obtain a set of transport equations for fermions which have the same form as Landau transport equations for normal Fermi liquid and Fermi liquid superconductor, respectively with all Landau parameters explicity given. Our theory can be viewed as a refined version of U(1) Gauge theory where all lattice effects are retained and strong correlation effects are reflected as strong Fermi-liquid interactions in the transport equation. Some experimental consequences are discussed.Comment: 19 page

    IT-Enabled Dynamic Capability Creation: A Perspective on Exploitative vs. Explorative IT Utilization

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    By focusing on today’s highly competitive and rapidly changing business environment, this study theorizes how organizations can create their dynamic capability from the utilization of information technology (IT) resources. The organizational exploitation and exploration perspective is adopted as the central theoretical basis of this study. A reflection on the exploitation and exploration of organizational IT management provides the possibility for theorizing multiple paths for IT-enabled dynamic capability creation. Under our theoretical development, the multiple paths involve different types of IT utilization capabilities that, in conjunction with organizational IT resources and other non-IT factors, lead to organizational dynamic capability. This study provides a theoretical basis for the role of IT in creating organizational dynamic capability. Specifically, it reveals the multiple types of interrelations between organizational IT resources and their utilization capabilities. This study serves as a basis for further empirical studies

    Knowledge Management Systems Diffusion in Chinese Enterprises: A Multi-Stage Approach with the Technology-Organization-Environment Framework

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    Many enterprises encounter difficulties during the process of KMS diffusion and thus fail to gain benefits from KMS adoption. This study aims to explain why some enterprises succeed while others fail in KMS diffusion. Based on technology diffusion theory and technologyorganization- environment (TOE) framework, we propose an integrated model to examine the influence of factors from the technological, organizational, and environmental aspects on the three-stage KMS diffusion process, i.e., initiation- adoption/adaptation-acceptance /routinization /infusion. In particular, we incorporate social-cultural factors into our model to examine its effect on KMS diffusion, which has not been paid enough attention by prior KMS studies. For the specific research context, we choose China and examine how socialcultural factors influence KMS diffusion process in Chinese enterprises. This study benefits academics by providing a process perspective of KMS diffusion and also provides practical guidance for Chinese enterprises which are engaging in KMS implementation

    Regulation of Ethanol-Related Behavior and Ethanol Metabolism by the Corazonin Neurons and Corazonin Receptor in Drosophila melanogaster

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    Impaired ethanol metabolism can lead to various alcohol-related health problems. Key enzymes in ethanol metabolism are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH); however, neuroendocrine pathways that regulate the activities of these enzymes are largely unexplored. Here we identified a neuroendocrine system involving Corazonin (Crz) neuropeptide and its receptor (CrzR) as important physiological regulators of ethanol metabolism in Drosophila. Crz-cell deficient (Crz-CD) flies displayed significantly delayed recovery from ethanol-induced sedation that we refer to as hangover-like phenotype. Newly generated mutant lacking Crz Receptor (CrzR01) and CrzR-knockdown flies showed even more severe hangover-like phenotype, which is causally associated with fast accumulation of acetaldehyde in the CrzR01 mutant following ethanol exposure. Higher levels of acetaldehyde are likely due to 30% reduced ALDH activity in the mutants. Moreover, increased ADH activity was found in the CrzR01 mutant, but not in the Crz-CD flies. Quantitative RT-PCR revealed transcriptional upregulation of Adh gene in the CrzR01. Transgenic inhibition of cyclic AMP-dependent protein kinase (PKA) also results in significantly increased ADH activity and AdhmRNA levels, indicating PKA-dependent transcriptional regulation of Adh by CrzR. Furthermore, inhibition of PKA or cAMP response element binding protein (CREB) in CrzR cells leads to comparable hangover-like phenotype to the CrzR01 mutant. These findings suggest that CrzR-associated signaling pathway is critical for ethanol detoxification via Crz-dependent regulation of ALDH activity and Crz-independent transcriptional regulation of ADH. Our study provides new insights into the neuroendocrine-associated ethanol-related behavior and metabolism

    Targeted Neural Dynamical Modeling

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    Latent dynamics models have emerged as powerful tools for modeling and interpreting neural population activity. Recently, there has been a focus on incorporating simultaneously measured behaviour into these models to further disentangle sources of neural variability in their latent space. These approaches, however, are limited in their ability to capture the underlying neural dynamics (e.g. linear) and in their ability to relate the learned dynamics back to the observed behaviour (e.g. no time lag). To this end, we introduce Targeted Neural Dynamical Modeling (TNDM), a nonlinear state-space model that jointly models the neural activity and external behavioural variables. TNDM decomposes neural dynamics into behaviourally relevant and behaviourally irrelevant dynamics; the relevant dynamics are used to reconstruct the behaviour through a flexible linear decoder and both sets of dynamics are used to reconstruct the neural activity through a linear decoder with no time lag. We implement TNDM as a sequential variational autoencoder and validate it on simulated recordings and recordings taken from the premotor and motor cortex of a monkey performing a center-out reaching task. We show that TNDM is able to learn low-dimensional latent dynamics that are highly predictive of behaviour without sacrificing its fit to the neural data

    Decidual glycodelin-A polarizes human monocytes into a decidual macrophage-like phenotype through Siglec-7

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    Decidual macrophages constitute 20-30% of the total leukocytes in the uterus of pregnant women, regulating the maternal immune tolerance and placenta development. Abnormal number or activities of decidual macrophages (dMs) are associated with fetal loss and pregnancy complications, such as preeclampsia. Monocytes differentiate into dMs in a decidua-specific microenvironment. Despite their important roles in pregnancy, the exact factors that regulate the differentiation into dMs remain unclear. Glycodelin-A (PAEP, hereafter referred to as GdA) is a glycoprotein that is abundantly present in the decidua, and plays an important role in fetomaternal defense and placental development. It modulates the differentiation and activity of several immune cell types residing in the decidua. In this study, we demonstrated that GdA induces the differentiation of human monocytes into dM-like phenotypes in terms of transcriptome, cell surface marker expression, secretome, and regulation of trophoblast and endothelial cell functions. We found that Sialic acid-binding Ig-like lectin 7 (Siglec-7) mediates the binding and biological actions of GdA in a sialic acid-dependent manner. We, therefore, suggest that GdA, induces the polarization of monocytes into dMs to regulate fetomatemal tolerance and placental development.Peer reviewe

    Structural Characterization And Condition For Measurement Statistics Preservation Of A Unital Quantum Operation

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    We investigate the necessary and sufficient condition for a convex cone of positive semidefinite operators to be fixed by a unital quantum operation Ï•\phi acting on finite-dimensional quantum states. By reducing this problem to the problem of simultaneous diagonalization of the Kraus operators associated with Ï•\phi, we can completely characterize the kind of quantum states that are fixed by Ï•\phi. Our work has several applications. It gives a simple proof of the structural characterization of a unital quantum operation that acts on finite-dimensional quantum states --- a result not explicitly mentioned in earlier studies. It also provides a necessary and sufficient condition for what kind of measurement statistics is preserved by a unital quantum operation. Finally, our result clarifies and extends the work of St{\o}rmer by giving a proof of a reduction theorem on the unassisted and entanglement-assisted classical capacities, coherent information, and minimal output Renyi entropy of a unital channel acting on finite-dimensional quantum state.Comment: 9 pages in revtex 4.1, minor revision, to appear in J.Phys.
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