Mobile-agent systems allow applications to distribute their resource consumption across the network. By prioritizing applications and publishing the cost of actions, it is possible for applications to achieve faster performance than in an environment where resources are evenly shared. We enforce the costs of actions through markets, where user applications bid for computation from host machines.We represent applications as collections of mobile agents and introduce a distributed mechanism for allocating general computational priority to mobile agents. We derive a bidding strategy for an agent that plans expenditures given a budget, and a series of tasks to complete. We also show that a unique Nash equilibrium exists between the agents under our allocation policy. We present simulation results to show that the use of our resource-allocation mechanism and expenditure-planning algorithm results in shorter mean job completion times compared to traditional mobile-agent resource allocation. We also observe that our resource-allocation policy adapts favorably to allocate overloaded resources to higher priority agents, and that agents are able to effectively plan expenditures, even when faced with network delay and job-size estimation error. 相似文献
The effect of Al content on MAO-modified silicas was evaluated on catalyst activity, on polymer properties and on residual metal content in the resulting polyethylenes. MAO-modified silicas were prepared by impregnating MAO toluene solutions in concentration range between 0.5 and 20.0 wt% Al/SiO2. Commercial MAO-modified silica (Witco) containing 24.4 wt% Al/SiO2 was used for comparative reasons. The resulting modified-silicas were employed as supports for grafting (nBuCp)2ZrCl2. Using external MAO as cocatalyst (Al/Zr=2000) no difference in catalyst activity was observed. Nevertheless, for Al/Zr=500, catalyst activities were shown to be higher for supported zirconocene systems containing 0.0-2.0 wt% Al/SiO2 range. According to DSC analysis, one Tm peak was detected for polymer obtained with catalyst prepared with 0.5 wt% Al/SiO2 (135 °C), but two Tm peaks were observed for polymers obtained with catalysts prepared with 10.0 wt% Al/SiO2 (136 and 141 °C) and 20.0 wt% Al/SiO2 (133 and 141 °C). 相似文献
There has been some controversy in the literature concerning the ability of ±3,4 methylenedioxymethamphetamine (MDMA) to reinforce operant responding in rats. In the present study, operant responding maintained by intravenous MDMA infusions increased when the fixed ratio schedule was increased from 1 to 5, decreased when saline was substituted for MDMA, and increased again when MDMA was reintroduced. During self-administration training, each infusion of MDMA was paired with the illumination of a light stimulus. The role of the continued presentation of this drug-associated stimulus in operant responding was measured in groups of rats that had received comparable exposure (average 19 daily test sessions) to MDMA during training. When either the light stimulus or the drug infusion was omitted, operant responding decreased gradually over the 15-day test period following training. When both the light stimulus and the MDMA infusion were omitted, there was a dramatic decrease in operant responding that persisted for the entire 15-day test period. These findings suggest that cues associated with MDMA develop conditioned properties that might contribute to drug taking. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
This paper explores the relationship between the concept of quality of life (QoL) and housing circumstances among the immigrant and local population of two neighbourhoods in Norway: Storhaug in Stavanger and Grünerløkka in Oslo. Objective data regarding housing circumstances, e.g., type of residence, dimension or overcrowding, is collected through spatial analysis and desktop-research. Inhabitants of these neighbourhoods are interviewed with the help of map-based questionnaires to collect both objective data regarding these housing circumstances as well as subjective data, e.g. reason of location and personal satisfaction with housing and QoL. The objective and subjective data is analysed geographically and statistically. This study finds that the immigrant group has less favourable housing circumstances than the local population. Circumstances such as type of residence, the reason of location and satisfaction with the residence are predictors for satisfaction with QoL between both groups. Being local or immigrant, as well as the study area, Storhaug and Grünerløkka, or the type of ownership were not significant predictors of satisfaction with QoL in this specific study. These findings provide a base for understanding the importance of housing circumstances for QoL. Due to the high percentage of the immigrant population and its projection in Norway, these investigations are expected to help practitioners identify housing features and design aspects that can impact on the overall satisfaction with QoL of both host and immigrant society.
We report the first heterologous production of a fungal rutinosidase (6‐O‐α‐L ‐rhamnopyranosyl‐β‐D ‐glucopyranosidase) in Pichia pastoris. The recombinant rutinosidase was purified from the culture medium to apparent homogeneity and biochemically characterized. The enzyme reacts with rutin and cleaves the glycosidic linkage between the disaccharide rutinose and the aglycone. Furthermore, it exhibits high transglycosylation activity, transferring rutinose from rutin as a glycosyl donor onto various alcohols and phenols. The utility of the recombinant rutinosidase was demonstrated by its use for the synthesis of a broad spectrum of rutinosides of primary (saturated and unsaturated), secondary, acyclic and phenolic alcohols as well as for the preparation of free rutinose. Moreover, the α‐L ‐rhamnosidase‐catalyzed synthesis of a chromogenic substrate for a rutinosidase assay – para‐nitrophenyl β‐rutinoside – is described.
Systematic characterisation of the reactivity of the lysine moieties in CRM197 towards N‐hydroxysuccinimide linkers bearing alkynes or azides is described. This involves two‐step conjugation of various glycans to CRM197 by click chemistry in a well‐defined manner. By semiquantitative LC‐MS/MS analysis of proteolytic digests of the conjugates formed, the reactivity of lysine residues in the protein was mapped and ranked. Computational analysis of the solvent accessibility of each lysine residue (based on the CRM197 crystal structure) established a correlation between reactivity and surface exposure. By this approach, conjugation involving lysine residues (normally a random process) can be controlled. It enables the preparation of lysine‐mediated glycoconjugates with improved batch‐to‐batch reproducibility, thereby producing neo‐glycoconjugates with more‐consistent biological activity. 相似文献
New β-cyclodextrin-based side-chain azo amphiphilic polyurethanes were prepared. Aggregation behaviour was studied by employing steady-state fluorescence and UV–Vis spectroscopy techniques and, determination of the hydrodynamic diameter of micellar aggregates in N,N-dimethyl formamide and N,N-dimethyl formamide/ethanol mixture solutions was done. An apparent polarity evidenced by increasing I1/I3 ratio with the increasing concentration of polyurethanes except the polyurethanes with stronger intra- and intermolecular hydrogen bonding of hard segments was obtained. Pyrene resides predominantly in the interfacial region in micellar aggregates that is sensitive to polarity changes due to solvent penetration. Apparent critical micelle concentration due to the presence of β-cyclodextrin was determined by steady-state fluorescence and UV–Vis spectroscopy techniques which ranged between 10?2 and 10?1 g/L. Binding constants from both spectroscopy techniques were determined. The values of hydrodynamic diameter for the amphiphilic poly(ether urethane)s show that their aggregation behaviour is different in function of chemical composition, type and content of hard segment and hydrophobe/hydrophile ratio. 相似文献
In this study, a sterile and biocompatible chitosan (CHI) gel for wound healing applications was formulated. CHI powder was treated in autoclave (ttCHI) to prepare sterile formulations. The heat treatment modified the CHI molecular weight, as evidenced by GPC analysis, and its physical–chemical features. Differential scanning calorimetry studies indicated that the macromolecules, before and after thermal treatment, differ in the strength of water-polymer interaction leading to different viscoelastic and flow properties. Thermally treated CHI exhibited the following effects: (i) increased the proliferation and migration of human foreskin foetal fibroblasts at 24 h; (ii) accelerated wound healing (measured as area of lesion) at 3 and 10 days in an in vivo model of pressure ulcers. These effects were linked to the increase of the hydroxyproline and haemoglobin content as well as Wnt protein expression. Moreover, we found a reduction of myeloperoxidase activity and TNF-α mRNA expression. These observations suggest the potential of this novel CHI gel in wound healing and other therapeutic applications. 相似文献