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"System effectiveness"
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Effectiveness of IT Service Management Capability: Value Co-Creation and Value Facilitation Mechanisms
Information technology service management (ITSM) has become the prevalent management approach to the provision of IT services worldwide. Researchers and practitioners, however, still lack an understanding regarding through which mechanisms and in which strategic contexts an ITSM capability contributes most to information systems (IS) effectiveness. Grounded in a service-dominant logic, we hypothesize that ITSM capability contributes to IS effectiveness through sustaining the alignment of the IS function with the business and contingent upon organizational IS strategic conservativeness. Data collected from 256 organizations confirms that direct effects from ITSM capability are mediated by IS-business alignment and strengthened by IS strategic conservativeness. Our findings provide evidence for a co-occurrence of value co-creation and value facilitation mechanisms in internal IT service relationships and for a greater value of ITSM capability in stable strategic contexts. Overall, our results contribute a novel understanding to the service literature of the distinct mechanisms and the facilitating contextual contingencies of value creation in IT service relationships.
Journal Article
Missing microbes : how the overuse of antibiotics is fueling our modern plagues
\"A critically important and startling look at the harmful effects of overusing antibiotics, from the field's leading expert Tracing one scientist's journey toward understanding the crucial importance of the microbiome, this revolutionary book will take readers to the forefront of trail-blazing research while revealing the damage that overuse of antibiotics is doing to our health: contributing to the rise of obesity, asthma, diabetes, and certain forms of cancer. In Missing Microbes, Dr. Martin Blaser invites us into the wilds of the human microbiome where for hundreds of thousands of years bacterial and human cells have existed in a peaceful symbiosis that is responsible for the health and equilibrium of our body. Now, this invisible eden is being irrevocably damaged by some of our most revered medical advances--antibiotics--threatening the extinction of our irreplaceable microbes with terrible health consequences. Taking us into both the lab and deep into the fields where these troubling effects can be witnessed firsthand, Blaser not only provides cutting edge evidence for the adverse effects of antibiotics, he tells us what we can do to avoid even more catastrophic health problems in the future. \"-- Provided by publisher.
Book
Accounting Information Systems Effectiveness: Evidence from the Nigerian Banking Sector
Aim/Purpose: The purpose of this study is to investigate the interrelationship among the quality measures of information system success, including system quality, information, quality, and service quality, that eventually influence accounting information systems effectiveness. Background: It is generally believed that investment in an information system offers opportunities to organizations for business process efficiency and effectiveness. Despite huge investments in accounting information systems, banks in Nigeria have not realized the full potential benefits of using these systems because of persistent failures. Few studies have been conducted to address the problem. Methodology: A survey research design was used to collect data, and a total of 287 questionnaires were retrieved from respondents in the Nigerian banking sector. Contribution: This study contributes to the understanding of the most important antecedent factors of the quality measures, the interrelationship among the quality measures, and the influence of these measures on the accounting information systems effectiveness. Findings: The result of the study revealed that security, ease of use, and efficiency are key features of system quality, while the information quality dimension includes accuracy, timeliness, and completeness. The result of the study further revealed that information quality and system quality have significant influences on accounting information systems effectiveness. Recommendations for Practitioners: This study provides practitioners with important measures for evaluation of AIS effectiveness in the context of Nigerian banks. Recommendation for Researchers: Future researchers may build on the findings of current study to conduct fur-ther research in the area of AIS effectiveness in different contexts. Future Research: This study examines only three quality measures of Delone and Mclean model and antecedents of information and system quality measures, neglecting contingency factor. Therefore, future study should include other factors to the AIS effectiveness model to help in developing more specific theory in AIS domain.
Journal Article
Data Link Effectiveness Evaluation Method Based on Improved ADC Model
Aiming at the problem of innumerable data link effectiveness evaluation bases, the battlefield environment adaptability is introduced into the ADC model to improve the accuracy of the ADC evaluation method based on the analysis of the ADC model. According to the mission and using mode of data link equipment, the evaluation index system and calculation method of data link equipment effectiveness are proposed, and the quantitative evaluation of data link system effectiveness is realized. The validity and scientificity of the model are verified by the example analysis, which provides an effective method for the effectiveness evaluation of data link equipment.
Journal Article
Non-Hermitian bulk–boundary correspondence in quantum dynamics
Bulk–boundary correspondence, a guiding principle in topological matter, relates robust edge states to bulk topological invariants. Its validity, however, has so far been established only in closed systems. Recent theoretical studies indicate that this principle requires fundamental revisions for a wide range of open systems with effective non-Hermitian Hamiltonians. Therein, the intriguing localization of nominal bulk states at boundaries, known as the non-Hermitian skin effect, suggests a non-Bloch band theory in which non-Bloch topological invariants are defined in generalized Brillouin zones, leading to a general bulk–boundary correspondence beyond the conventional framework. Here, we experimentally observe this fundamental non-Hermitian bulk–boundary correspondence in discrete-time non-unitary quantum-walk dynamics of single photons. We demonstrate pronounced photon localizations near boundaries even in the absence of topological edge states, thus confirming the non-Hermitian skin effect. Facilitated by our experimental scheme of edge-state reconstruction, we directly measure topological edge states, which are in excellent agreement with the non-Bloch topological invariants. Our work unequivocally establishes the non-Hermitian bulk–boundary correspondence as a general principle underlying non-Hermitian topological systems and paves the way for a complete understanding of topological matter in open systems.
Measurements of non-Hermitian photon dynamics show boundary-localized bulk eigenstates given by the non-Hermitian skin effect. A fundamental revision of the bulk–boundary correspondence in open systems is required to understand the underlying physics.
Journal Article
Entanglement Phase Transition Induced by the Non-Hermitian Skin Effect
Recent years have seen remarkable development in open quantum systems effectively described by non-Hermitian Hamiltonians. A unique feature of non-Hermitian topological systems is the skin effect, anomalous localization of an extensive number of eigenstates driven by nonreciprocal dissipation. Despite its significance for non-Hermitian topological phases, the relevance of the skin effect to quantum entanglement and critical phenomena has remained unclear. Here, we find that the skin effect induces a nonequilibrium quantum phase transition in the entanglement dynamics. We show that the skin effect gives rise to a macroscopic flow of particles and suppresses the entanglement propagation and thermalization, leading to the area law of the entanglement entropy in the nonequilibrium steady state. Moreover, we reveal an entanglement phase transition induced by the competition between the unitary dynamics and the skin effect even without disorder or interactions. This entanglement phase transition accompanies nonequilibrium quantum criticality characterized by a nonunitary conformal field theory whose effective central charge is extremely sensitive to the boundary conditions. We also demonstrate that it originates from an exceptional point of the non-Hermitian Hamiltonian and the concomitant scale invariance of the skin modes localized according to the power law. Furthermore, we show that the skin effect leads to the purification and the reduction of von Neumann entropy even in Markovian open quantum systems described by the Lindblad master equation. Our work opens a way to control the entanglement growth and establishes a fundamental understanding of phase transitions and critical phenomena in open quantum systems far from thermal equilibrium.
Journal Article
Fundamental limits and non-reciprocal approaches in non-Hermitian quantum sensing
Unconventional properties of non-Hermitian systems, such as the existence of exceptional points, have recently been suggested as a resource for sensing. The impact of noise and utility in quantum regimes however remains unclear. In this work, we analyze the parametric-sensing properties of linear coupled-mode systems that are described by effective non-Hermitian Hamiltonians. Our analysis fully accounts for noise effects in both classical and quantum regimes, and also fully treats a realistic and optimal measurement protocol based on coherent driving and homodyne detection. Focusing on two-mode devices, we derive fundamental bounds on the signal power and signal-to-noise ratio for any such sensor. We use these to demonstrate that enhanced signal power requires gain, but not necessarily any proximity to an exceptional point. Further, when noise is included, we show that nonreciprocity is a powerful resource for sensing: it allows one to exceed the fundamental bounds constraining any conventional, reciprocal sensor.
Non-Hermitian properties were proposed to be beneficial to sensing but it is not clear if this concept can be extended to the quantum regime. Here, Lau and Clerk self-consistently consider the impact of noise and measurement, and identify that nonreciprocity can improve sensing capabilities.
Journal Article
Inference and analysis of cell-cell communication using CellChat
Understanding global communications among cells requires accurate representation of cell-cell signaling links and effective systems-level analyses of those links. We construct a database of interactions among ligands, receptors and their cofactors that accurately represent known heteromeric molecular complexes. We then develop CellChat, a tool that is able to quantitatively infer and analyze intercellular communication networks from single-cell RNA-sequencing (scRNA-seq) data. CellChat predicts major signaling inputs and outputs for cells and how those cells and signals coordinate for functions using network analysis and pattern recognition approaches. Through manifold learning and quantitative contrasts, CellChat classifies signaling pathways and delineates conserved and context-specific pathways across different datasets. Applying CellChat to mouse and human skin datasets shows its ability to extract complex signaling patterns. Our versatile and easy-to-use toolkit CellChat and a web-based Explorer (
http://www.cellchat.org/
) will help discover novel intercellular communications and build cell-cell communication atlases in diverse tissues.
Single-cell methods record molecule expressions of cells in a given tissue, but understanding interactions between cells remains challenging. Here the authors show by applying systems biology and machine learning approaches that they can infer and analyze cell-cell communication networks in an easily interpretable way.
Journal Article
Fraud Detection in Mobile Payment Systems using an XGBoost-based Framework
Mobile payment systems are becoming more popular due to the increase in the number of smartphones, which, in turn, attracts the interest of fraudsters. Extant research has therefore developed various fraud detection methods using supervised machine learning. However, sufficient labeled data are rarely available and their detection performance is negatively affected by the extreme class imbalance in financial fraud data. The purpose of this study is to propose an XGBoost-based fraud detection framework while considering the financial consequences of fraud detection systems. The framework was empirically validated on a large dataset of more than 6 million mobile transactions. To demonstrate the effectiveness of the proposed framework, we conducted a comparative evaluation of existing machine learning methods designed for modeling imbalanced data and outlier detection. The results suggest that in terms of standard classification measures, the proposed semi-supervised ensemble model integrating multiple unsupervised outlier detection algorithms and an XGBoost classifier achieves the best results, while the highest cost savings can be achieved by combining random under-sampling and XGBoost methods. This study has therefore financial implications for organizations to make appropriate decisions regarding the implementation of effective fraud detection systems.
Journal Article