Firm Size as Moderator to Non-Linear Leverage-Performance Relation: an Emerging Market Review

The purpose of this research was to investigate leverage-performance relation with moderating firm size in developing countries like Pakistan. Data were collected from 304 Pakistani non-financial firms for the period of 2005-2013. It is found that overall leverage-performance relation is negative for all types of firms. However,such losses are more prominent for small size firms. Results also show that the leverage-performance relation is nonlinear for medium and large size firms. However, these firms are not targeting optimal level and overleveraging that ultimately decrease their profits. So, financial managers of small size firms should avoid debt financing while for large and medium size firms, managers need to adjust their debt ratio to its optimal level

Dynamics of interacting phantom and quintessence dark energies

We present models, in which phantom energy interacts with two different types of dark energies including variable modified Chaplygin gas (VMCG) and new modified Chaplygin gas (NMCG). We then construct potentials for these cases. It has been shown that the potential of the phantom field decreases from a higher value with the evolution of the Universe.Comment: 7 pages, 6 figures, accepted for publication in Astrophysics and Space Scienc

Generalized Holographic Dark Energy Model

In this paper, the model of holographic Chaplygin gas has been extended to two general cases: first is the case of modified variable Chaplygin gas and secondly of the viscous generalized Chaplygin gas. The dynamics of the model are expressed by the use of scalar fields and the scalar potentials.Comment: 12 pages, to appear in Eur. Phys. J.

Performance of publish/subscribe middleware in mobile wireless networks

Publish/subscribe middlewares are becoming popular for distributed applications because of their flexible and scalable nature. Anonymous and loosely-coupled communication between publisher and subscriber, along with the inherently asynchronous nature of these systems, help them adapt quickly to changing environments, making them a good choice for mobile cellular networks. This paper studies publish/subscribe middleware performance in such networks in detail. As a first step, the paper characterizes a popular implementation of publish/subscribe system for the mobile domain, studying and analyzing the effect of different mobility parameters, which to the best of our knowledge is the first experimental research on the performance behavior of publish/subscribe systems in a mobile wireless domain. As a second step the paper presents the design, implementation and evaluation of middleware level handoffs, a well known solution to extend publish/subscribe systems to a mobile domain, and identifies the performance concerns of such extensions. The results show that such handoff protocols involving two brokers are impractical from a performance perspective under highly dynamic and unreliable mobile wireless settings. The paper identifies the basic reason for the limitations of middleware level handoffs

A framework to achieve guaranteed QoS for applications and high system performance in multi-institutional grid computing

Providing QoS guarantees to the applications in a multi-institutional Grid is a challenging task. Although advance reservations (ARs) can provide QoS guarantees for the applications, they often seriously degrade system performance for resource owners. In this paper, we present a framework for AR based resource sharing that not only provides QoS guarantees for the applications but also ensures high utilization of the resources. This paper focuses on the application-to-resource mapping component of the framework as our results show that traditional mapping algorithms used with best effort jobs do not perform well for ARs. The paper proposes a set of algorithms for mapping ARs and investigates their performance in detail. The paper then presents a novel algorithm that outperforms a number of other algorithms in almost every respect for a wide range of workload parameters. Rigorous experimentation proves the efficacy of our algorithm and brings important insights into the dynamics of the system

Engineering grid applications and middleware for high performance

Meeting QoS objectives of applications while maintaining high system utilization is a challenging task in multi-institutional Grids. In this paper, we effectively engineer Grid applications and resource management middleware for achieving user satisfaction and high resource utilizations. The paper presents a complete framework based on advance reservations (ARs) for resource management in Grids. The framework is capable of providing QoS guarantees to applications while maintaining high resource utilizations. The paper focuses on the scheduling component of the framework and presents a novel heuristic-based algorithm, Grid Scheduling with Deadlines (GSD), for an NP-Complete problem of scheduling ARs with laxities on a shared resource. GSD can be configured with the help of pluggable strategies to adapt to various workload conditions and needs of the system. The paper studies with the aid of an extensive set of experiments the effect of various workload and system parameters on system performance. It is not always possible to accurately predict the runtimes of the jobs. The paper discusses the impact of error in user-estimated runtimes on system performance and investigates strategies to avoid substandard performance resulting from such inaccuracies. Experimental results demonstrate the efficacy of our methodology. Copyright 2007 ACM