The Study of Corporate M&As

Abstract According to the objective and inherent logical coherence of research subject, the thesis is composed of six chapters. The first chapter provides the theoretical background for the thesis. The author reviews and analyzes the western motive theories of corporate M&As so as to clearly recognize them. The commemt and analysis lay a foundation for discussion of the related problem...学位：经济学博士院系专业：经济学院经济系_世界经济学号：B20010901

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Advanced resource connector (ARC) - the grid middleware of the NorduGrid

Summary form only given. The advanced resource connector (ARC), or the NorduGrid middleware, is an open source software solution enabling production quality computational and data grids. Since the first release (May 2002), the middleware is deployed and being used in production environments. Emphasis is put on scalability, stability, reliability and performance of the middleware. A growing number of grid deployments chose ARC as their middleware, thus building one of the largest production grids of the world. The NorduGrid middleware integrates computing resources (commodity computing clusters managed by a batch system or standalone workstations) and storage elements, making them available via a secure common grid layer. ARC provides a reliable implementation of the fundamental grid services, such as information services, resource discovery and monitoring, job submission and management, brokering and data management. The middleware builds upon standard open source solutions like OpenLDAP, OpenSSL, SASL and Globus Toolkit 2 (GT2) libraries. NorduGrid provides innovative solutions essential for a production quality middleware: Grid Manager, ARC GridFTP server, information model and providers (NorduGrid schema), user interface and broker (a "personal" broker integrated into the user interface), extended Resource Specification Language (xRSL), and the monitoring system. ARC solutions are replacements and extensions of the original GT2 services, the middleware does not use most of the core GT2 services, such as the GRAM, the GT2 job submission commands, the WUftp-based gridftp server, the gatekeeper, the job-manager, the GT2 information providers and schemas. Moreover, ARC extended the RSL and made the Globus MDS functional. ARC is thus much more than GT2 - it offers its own set of grid services built upon the GT2 librarie

Computing in High Energy and Nuclear Physics (CHEP) 2012

Scientific research communities have benefited recently from the increasing availability of computing and data infrastructures with unprecedented capabilities for large scale distributed initiatives. These infrastructures are largely defined and enabled by the middleware they deploy. One of the major issues in the current usage of research infrastructures is the need to use similar but often incompatible middleware solutions. The European Middleware Initiative (EMI) is a collaboration of the major European middleware providers ARC, dCache, gLite and UNICORE. EMI aims to: deliver a consolidated set of middleware components for deployment in EGI, PRACE and other Distributed Computing Infrastructures; extend the interoperability between grids and other computing infrastructures; strengthen the reliability of the services; establish a sustainable model to maintain and evolve the middleware; fulfill the requirements of the user communities. This paper presents the consolidation and development objectives of the EMI software stack covering the next two years. Details will be given concerning how the most important requirements of the key user groups, including the high energy physics community, were taken into account. The EMI development roadmap will be introduced along the four technical areas of compute, data, security and infrastructure. The compute area plan focuses on consolidation of standards and agreements through an unified interface for job submission and management, a common format for accounting, the wide adoption of GLUE schema version 2.0 and the provision of a common framework for the execution of parallel jobs. The security area is working towards a unified security model and lowering the barriers to Grid usage by allowing users to gain access with their own credentials. The data area is focusing on implementing standards to ensure interoperability with other grids and industry components and to reuse already existing clients in operating systems and open source distributions. One of the highlights of the infrastructure area is the consolidation of the information system services via the creation of a common information backbone. Wherever possible early results of the consolidation plan and the ongoing development will be covered by introducing EMI technical agreements and development prototypes

Grid Information System Interoperability: The Need For A Common Information Model

A fundamental building block of any Grid infrastructures is the Grid information service and the information model. The information model describes the entities and relationships between entities within the infrastructure along with their semantics. The realization into a concrete data model defines the syntax by which these concepts can be exchanged. This data model enables consumers of information to efficiently find the information they require and ensures that there is agreement on the meaning with the information producer. The need for a common information model is therefore critical for the seamless interoperation of Grid infrastructures. A number of example interoperation activities are presented which highlight this point and the requirement for a common schema in general. An attempt to achieve interoperability between multiple Grid infrastructures, which was demonstrated at Super Computing 2006, helped motivate work on a common schema within the Open Grid Forum. The result of this effort, GLUE 2.0, which in itself defines the current view of Grid computing, is presented

The NorduGrid project: using Globus toolkit for building GRID infrastructure

The NorduGrid is the pioneering Grid project in Scandinavia. The purpose of the project is to create a Grid computing infrastructure in Nordic countries. The cornerstone of the infrastructure adopted at NorduGrid is the Globus toolkit developed at Argonne National Laboratory and University of Southern California. It is, however, missing several important high-level services. With the need to provide working production system, NorduGrid has developed its own solution for the most essential parts. An early prototype implementation of the proposed architecture is being tested and further developed. Aiming at simple but yet functional system capable of handling common computational problems encountered in the Nordic scientific communities, we were choosing simple, but still functional solutions with the necessary parts implemented first. (C) 2003 Elsevier Science B.V. All rights reserved