the distribution of extracellular enzyme activities in particle-size fractions of sediments was investigated in a subtropical mangrove ecosystem. five enzymes involved in carbon (c), nitrogen (n), and phosphorus (p) cycling were analyzed in the sand, silt, and clay of sediments. among these fractions, the highest activities of phenol oxidase (pho), β-d glucosidase (glu), and n-acetyl-glucosimin...

The ability to store energy enables organisms to deal with temporarily harsh and uncertain conditions. Empirical studies have demonstrated that organisms adapted to fluctuating energy availability plastically adjust their storage strategies. So far, however, theoretical studies have investigated general storage strategies only in constant or deterministically varying environments. In this study...

Data distribution is one of the crucial issues in Data Base Management Systems (DBMS) in general and in Mobile environment in Particular. It is important because, if not properly managed, it will cause reduction in data availability, which in turn causes more rejections in transactions. Replication algorithms (e.g., CCM) are used to improve data availability. However, the database replication a...

Computational grids have the potential for solving large-scale scientific problems using heterogeneous and geographically distributed resources. However, a number of the major technical hurdles must overcome before this potential can be realized. One problem that is critical to effective utilization of computational grids and gives a certain Quality of Service (QoS) for grid users is the effici...

Patterns of resource availability and heterogeneity shape the composition, productivity, and dynamics of plant assemblages in a wide variety of terrestrial ecosystems. Despite this, the responses of plant assemblages to simultaneous changes in the availability and heterogeneity of more than a single resource are virtually unknown. To fill this gap, microcosms consisting of assemblages formed by...

Computer resource allocation represents a significant challenge particularly for multiprocessor systems, which consist of shared computing resources to be allocated among co-runner processes and threads. While an efficient resource allocation would result in a highly efficient and stable overall multiprocessor system and individual thread performance, ineffective poor resource allocation causes...

G. Pujolle Laboratoire MASI Universite P. et M. Curie 45 avenue des Etats-Unis 78000 Versailles France In this paper, we present a general approach to obtain the exact stability condition of systems with resource sharing. Two kinds of allocation disciplines are studied: 1.the allocation may be performed in parallel: as soon as a resource is free , if a customer is waiting, the allocation begins...