Information System Capabilities and Organizational Performance: Comparing Three Models

How information system capabilities affect firm performance is an important issue. However, different research approaches often result in inconsistent results. This study compares three conceptual (K-based view, resource-based view, and contingency-based view) and two modeling approaches (antecedents versus moderators) that can be used to assess the strategic value of information systems. The goal is to examine different ways to model various organizational factors. We also provide three different views to buttress arguments about the need for different types of moderator analyses. The advantage of such an approach is that managers and researchers can better differentiate potential influential factors into antecedents and moderators, and understand their different roles in KM implementation. This study uses data collected from 274 organizations to compare different prevailing views in KM research. The result indicates that the contingency approach can provide more insight into the role of different contextual variables. Some variables, such as the business process complexity and market orientation, found insignificant in the contingency-based model are found to be significant antecedents for improving managerial performance. Some variables that are found insignificant in the resource-based model are found to be significant moderators. For example, business process complexity and information technology (IT) support are not significant, as enablers proved to moderate the relationship between KMC and financial performance as homologizer and suppressor, respectively. The relationship between KM capabilities and financial performance is also moderated by leadership style and IT readiness of an organization. The results of this analysis show that the contingency model, with moderating effect, is more comprehensive and meaningful for future research. Available at: https://aisel.aisnet.org/pajais/vol9/iss1/2

Linear programming bounds for quantum amplitude damping codes

Given that approximate quantum error-correcting (AQEC) codes have a potentially better performance than perfect quantum error correction codes, it is pertinent to quantify their performance. While quantum weight enumerators establish some of the best upper bounds on the minimum distance of quantum error-correcting codes, these bounds do not directly apply to AQEC codes. Herein, we introduce quantum weight enumerators for amplitude damping (AD) errors and work within the framework of approximate quantum error correction. In particular, we introduce an auxiliary exact weight enumerator that is intrinsic to a code space and moreover, we establish a linear relationship between the quantum weight enumerators for AD errors and this auxiliary exact weight enumerator. This allows us to establish a linear program that is infeasible only when AQEC AD codes with corresponding parameters do not exist. To illustrate our linear program, we numerically rule out the existence of three-qubit AD codes that are capable of correcting an arbitrary AD error.Comment: 5 page

Evolutionary Signatures of Common Human Cis-Regulatory Haplotypes

Variation in gene expression may give rise to a significant fraction of inter-individual phenotypic variation. Studies searching for the underlying genetic controls for such variation have been conducted in model organisms and humans in recent years. In our previous effort of assessing conserved underlying haplotype patterns across ethnic populations, we constructed common haplotypes using SNPs having conserved linkage disequilibrium (LD) across ethnic populations. These common haplotypes cluster into a simple evolutionary structure based on their frequencies, defining only up to three conserved clusters termed ‘haplotype frameworks’. One intriguing preliminary finding was that a significant portion of reported variants strongly associated with cis-regulation tags these globally conserved haplotype frameworks. Here we expand the investigation by collecting genes showing stringently determined cis-association between genotypes and expression phenotypes from major studies. We conducted phylogenetic analysis of current major haplotypes along with the corresponding haplotypes derived from chimpanzee reference sequences. Our analysis reveals that, for the vast majority of such cis-regulatory genes, the tagging SNPs showing the strongest association also tag the haplotype lineages directly separated from ancestry, inferred from either chimpanzee reference sequences or the allele frequency-derived haplotype frameworks, suggesting that the differentially expressed phenotypes were evolved relatively early in human history. Such evolutionary signatures provide keys for a more effective identification of globally-conserved candidate regulatory haplotypes across human genes in future epidemiologic and pharmacogenetic studies

Elastic and electronic properties of Ti2Al(CxN1−x) solid solutions

The elastic coefficients and mechanical properties (bulk modulus, shear modulus, Young\u27s modulus and Poisson\u27s ratio) of Ti2Al(CxN1−x) continuous solid solutions for x from 0 to 1 are calculated using ab initio DFT methods on 4×4×1 supercell models. It is shown that the properties of these solid solutions do not vary linearly with x. Although the lattice constant c is almost constant for x≤0.5, a increases linearly. For x\u3e0.5, c starts to increase with x while the rate of increase in a slows down. For x between 0.5 and 0.85, the elastic coefficients and the mechanical parameters show interesting dependence on x and crossovers, signifying the complex interplay in the structure and properties in Ti2Al(CxN1−x) solid solutions. The nonlinear variations in mechanical properties are explained in terms of subtle difference in the electronic structure and bonding between nitrides and carbides in complex MAX phase compounds

Ab initio tensile experiment on a model of an intergranular glassy film in β-Si3N4 with prismatic surfaces

We report the results of a large-scale ab initio simulation of an intergranular glassy film (IGF) model in β-Si3N4. It is shown that the stress-strain behavior under uniaxial load in the model with prismatic surfaces and few defective bonds is very different from an earlier IGF model with basal planes. The results are explained by the fundamental electronic structure of the model. This work is supported by the U.S. Department of Energy under Grant No. DE-FG02-84DR45170. This research used the resources of NERSC supported by the Office of Science of DOE under Contract No. DE-AC03-76SF00098

Ab initio tensile experiment on a model of an intergranular glassy film in β-Si3N4 with prismatic surfaces

This is the published version. Copyright 2009 American Institute of PhysicsWe report the results of a large-scale ab initio simulation of an intergranular glassy film (IGF) model in β-Si3N4. It is shown that the stress-strain behavior under uniaxial load in the model with prismatic surfaces and few defective bonds is very different from an earlier IGF model with basal planes. The results are explained by the fundamental electronic structure of the model

Complex Nonlinear Deformation of Nanometer Intergranular Glassy Films in β−Si3N4

This is the published version. Copyright 2005 American Physical SocietyThe mechanical properties of a model of Y-doped intergranular glassy film in silicon nitride ceramics are studied by large-scale ab initio modeling. By linking directly to its electronic structure, it is shown that this microstructure has a complex nonlinear deformation under stress and Y doping significantly enhances the mechanical properties. The calculation of the electrostatic potential across the film supports the space charge model in ceramic microstructures

Theoretical study of the elasticity, mechanical behavior, electronic structure, interatomic bonding, and dielectric function of an intergranular glassy film model in prismatic β-Si3N4

This is the published version. Copyright © 2010 The American Physical SocietyMicrostructures such as intergranular glassy films (IGFs) are ubiquitous in many structural ceramics. They control many of the important physical properties of polycrystalline ceramics and can be influenced during processing to modify the performance of devices that contain them. In recent years, there has been intense research, both experimentally and computationally, on the structure and properties of IGFs. Unlike grain boundaries or dislocations with well-defined crystalline planes, the atomic scale structure of IGFs, their fundamental electronic interactions, and their bonding characteristics are far more complicated and not well known. In this paper, we present the results of theoretical simulations using ab initio methods on an IGF model in β-Si3N4 with prismatic crystalline planes. The 907-atom model has a dimension of 14.533 Å×15.225 Å×47.420 Å. The IGF layer is perpendicular to the z axis, 16.4 Å wide, and contains 72 Si, 32 N, and 124 O atoms. Based on this model, the mechanical and elastic properties, the electronic structure, the interatomic bonding, the localization of defective states, the distribution of electrostatic potential, and the optical dielectric function are evaluated and compared with crystalline β-Si3N4. We have also performed a theoretical tensile experiment on this model by incrementally extending the structure in the direction perpendicular to the IGF plane until the model fully separated. It is shown that fracture occurs at a strain of 9.42% with a maximum stress of 13.9 GPa. The fractured segments show plastic behavior and the formation of surfacial films on the β-Si3N4. These results are very different from those of a previously studied basal plane model [J. Chen et al., Phys. Rev. Lett. 95, 256103 (2005)] and add insights to the structure and behavior of IGFs in polycrystalline ceramics. The implications of these results and the need for further investigations are discussed

Curvature-relevant analysis model of eccentrically loaded circular concrete-filled steel tube columns

The existence of curvature can reduce the effective confining pressure within concrete-filled steel tube (CFST) columns under eccentric compression. The existing analysis method ignores such an effect and still treats the confining pressure as constant across the whole section as if it is under axial compression. In this paper, the authors have made significant improvements on the existing model, so that the curvature effect can be taken into account to properly interpret the non-linear behaviour of eccentrically loaded CFSTcolumns. Meanwhile, shortening between two hinges is an important data output in test programmes of this type, which has been completely neglected by the existing analysis method. This improved method also provides calculation steps to track the value of shortening for each load increment. Unknown parameters in this new method are determined on the basis of data fitting of 87 specimens from previous researchers' test programmes. The following parameters are incorporated in this study: effective tube length (660-4670 mm), diameter of tube (76-600 mm), tube thickness (1.52-8.81 mm), yield strength of tube (256.4-517.0 MPa), cylinder strength of concrete (26.42-112.70 MPa) and eccentricity (9.4-300 mm). The load-axial displacement, load-deflection and moment-curvature curves predicted by the new method agree well with their measured counterparts in the tests

Metabolic Stress-Induced Phosphorylation of KAP1 Ser473 Blocks Mitochondrial Fusion in Breast Cancer Cells

Mitochondrial dynamics during nutrient starvation of cancer cells likely exert profound effects on their capability for metastatic progression. Here, we report that KAP1 (TRIM28), a transcriptional coadaptor protein implicated in metastatic progression in breast cancer, is a pivotal regulator of mitochondrial fusion in glucose-starved cancer cells. Diverse metabolic stresses induced Ser473 phosphorylation of KAP1 (pS473-KAP1) in a ROS- and p38-dependent manner. Results from live-cell imaging and molecular studies revealed that during the first 6 to 8 hours of glucose starvation, mitochondria initially underwent extensive fusion, but then subsequently fragmented in a pS473-KAP1-dependent manner. Mechanistic investigations using phosphorylation-defective mutants revealed that KAP1 Ser473 phosphorylation limited mitochondrial hyperfusion in glucose-starved breast cancer cells, as driven by downregulation of the mitofusin protein MFN2, leading to reduced oxidative phosphorylation and ROS production. In clinical specimens of breast cancer, reduced expression of MFN2 corresponded to poor prognosis in patients. In a mouse xenograft model of human breast cancer, there was an association in the core region of tumors between MFN2 downregulation and the presence of highly fragmented mitochondria. Collectively, our results suggest that KAP1 Ser473 phosphorylation acts through MFN2 reduction to restrict mitochondrial hyperfusion, thereby contributing to cancer cell survival under conditions of sustained metabolic stress