RAPD Analysis, Plasmid Profiles, Antibiotic Resistance and Occurrence of the Van Genes in Enterococcus Species Isolated from Human And Poultry

The purpose of this study was to evaluate the molecular relatedness of the Enterococcus spp. isolated among poultry and clinical samples. A total of 71 poultry isolates and 29 clinical isolates were examined in this study. The poultry samples obtained from market in Sri Serdang, Selangor and Makmal Kesihatan Awam Veterinar. Petaling Jaya, whereas the clinical samples were from Hospital Universiti. Kuala Lumpur. E. faecalis (41 of 71 , 58%) was the dominant species isolated from poultry samples. Besides that, E. faecium (3 of 71, 4%). E. casseliflavus (4 of 71, 6%), E. durans (18 of 71, 25%) and E. hirae (5 of 71, 7%) were also detected. Twenty-nine isolates from clinical samples were identified as E. faeca/is (19 isolates, 66%), E. faecium (8 isolates, 28%), E. mundtii (1 isolate, 3%) and E. raffinosus (1 isolate, 3%). All isolates were resistant against ceftazidime, erythromycin. kanamycin, nalidixic acid and streptomycin (100%). Clinical isolates also demonstrated high resistance to cephalothin, gentamicin and norf\oxacin (100%). Sixty-four of 71 poultry isolates, and 26 of 29 clinical isolates were resistant to vancomycin and this indicated high prevalence of vancomycin resistant enterococci detected among the isolates. All seventyone isolates from poultry exhibited multiple resistance with Multiple Antibiotic Resistance (MAR) indices ranging between 0.53 to 1.0 while for clinical isolates the range were between 0.6 to 0.86. These high MAR index suggests that a\l the isolates originated from high risk sources. According to plasmid profile analysis. 29 plasmid patterns were observed among poultry isolates with the plasmid DNA bands ranging in sizes from 1.1 to 35.8 megadalton. The plasmid analysis among clinical isolates were grouped into 9 plasmid patterns ranging in sizes from 1.85 to 35.8 megadalton. RAPD-PCR has been used to generate polymorphic genomic fingerprints to discriminate the enterococci isolates. Two primers (GEN15008 and GEN15009) were chosen after screening a set of 10 primers. These two primers yield reproducible and typeable results in most isolates examined with the bands ranging in sizes from 0.25 kb to 5.0 kb. From the dendrogram generated to study the interspecific relatedness among the isolates. 2 main clusters were observed and further subdivided into several subclusters defining the genetic heterogeneity among the isolates. The vanA specific (732 bp) fragment was detected in 96 of 100 (96%) of the isolates. 29 (100%) of dinical isolates and 67 of 71 (94%) of poultry isolates were positive for vanA gene. 4 of 71 (6%) of poultry were positive for vanC2IC3 gene (439 bp). Isolates containing the vanS or vanC1 gene were not found

MST construction in O

We consider a simple model for overlay networks, where all n processes are connected to all other processes, and each message contains at most O(log n) bits. For this model, we present a distributed algorithm that constructs a minimumweight spanning tree in O(log log n) communication rounds, where in each round any process can send a message to each other process. This result is the first to break the Ω(log n) parallel time complexity barrier with small message sizes. Categories and Subject Descriptors F.2 [theory of computation]: analysis of algorithms and problem complexity; G.2.2 [mathematics of computing]: discrete mathematics—graph theor

An incentive-compatible multi-armed bandit mechanism

Abstract. This paper presents a truthful sponsored search auction based on an incentive-compatible multi-armed bandit mechanism. The mechanism described combines several desirable traits. The mechanism gives advertisers the incentive to report their true bid, learns the click-through rate for advertisements, allows for slots with different quality, and loses the minimum welfare during the sampling process. The underlying generalization of the multi-armed bandit mechanism addresses the interplay between exploration and exploitation in an online setting that is truthful in high probability while allowing for slots of different quality. As the mechanism progresses the algorithm more closely approximates the hidden variables (click-though rates) in order to allocate advertising slots to the best advertisements. The resulting mechanism obtains the optimal welfare apart from a tightly bounded loss of welfare caused by the bandit sampling process. Of independent interest, in the field of economics it has long been recognized that preference elicitation is difficult to achieve, mainly as people are unaware of how much happiness a particular good will bring to them. In this paper we alleviate this problem somewhat by introducing a valuation-discovery process to the mechanism which results in a preference-elicitation mechanism for advertisers and search engines.

ABSTRACT Generalized Trade Reduction Mechanisms

When designing a mechanism there are several desirable properties to maintain such as incentive compatibility (IC), individual rationality (IR), and budget balance (BB). It is well known [15] that it is impossible for a mechanism to maximize social welfare whilst also being IR, IC, and BB. There have been several attempts to circumvent [15] by trading welfare for BB, e.g., in domains such as double-sided auctions[13], distributed markets[3] and supply chain problems[2, 4]. In this paper we provide a procedure called a Generalized Trade Reduction (GTR) for single-value players, which given an IR and IC mechanism, outputs a mechanism which is IR, IC and BB with a loss of welfare. We bound the welfare achieved by our procedure for a wide range of domains. In particular, our results improve on existing solutions for problems such as double sided markets with homogenous goods, distributed markets and several kinds of supply chains. Furthermore, our solution provides budget balanced mechanisms for several open problems such as combinatorial double-sided auctions and distributed markets with strategic transportation edges

An Adaptive Sponsored Search Mechanism δ-Gain Truthful in Valuation, Time, and Budget

This paper presents an online sponsored search auction that motivates advertisers to report their true budget, arrival time, departure time, and value per click. The auction is based on a modified Multi-Armed Bandit (MAB) mechanism that allows for advertisers who arrive and depart in an online fashion, have a value per click, and are budget constrained. In tackling the problem of truthful budget, arrival and departure times, it turns out that it is not possible to achieve truthfulness in the classical sense (which we show in a companion paper). As such, we define a new concept called δ-gain. δ-gain bounds the utility a player can gain by lying as opposed to his utility when telling the truth. Building on the δ-gain concept we define another new concept called relative ɛ-gain, which bounds the relative ratio of the gain a player can achieve by lying with respect to his true utility. We argue that for many practical applications if the δ-gain and or the relative ɛ-gain are small, then players will not invest time and effort in making strategic choices but will truthtell as a default strategy. These concepts capture the essence of dominant strategy mechanisms as they lead the advertiser to choose truthtelling over other strategies. In order to achieve δ-gain truthful mechanism this paper also presents a new payment scheme, Time series Truthful Payment Scheme (TTPS), for an online budget-constrained auction mechanism. The payment scheme is a generalization of the VCG principles for an online scheduling environment with budgeted players. Using the concepts of δ-gain truthful we present the only known budget-constrained sponsored search auction with truthful guarantees on budget, arrivals, departures, and valuations. Previous works that dea

Single value combinatorial auctions and implementation in undominated strategies

Single value Combinatorial Auctions (CA) are a strict generalization of single minded CA: each player may desire any one of several different bundles, but has the same value for each of them. Our main result provides the first polynomial time strategic mechanism for this case, using a new notion of “algorithmic implementation in undominated strategies”. We show that this general notion, which is an alternative to the now-standard truthfulness notion, captures almost all the advantages of the truthfulness notion. By using it, we achieve a close-to-optimal social welfare approximation. In addition, we give two general techniques to overcome strategic behavior in two special cases: (1) For the case where player values are the only private information (the “known ” case), we provide a deterministic technique to convert algorithms to truthful ascending mechanisms that almost preserve the original approximation ratio, and (2) For the case where players are single minded, we provide a deterministic technique to convert some truthful mechanisms for the known case to mechanisms in undominated strategies for the unknown case, that preserve the original approximation ratio