Thermal inactivation of Escherichia coli in camel milk

Camels subsist and produce milk in desert pastures not utilized by other domesticated herbivores. Developing the camel milk industry can improve the economy of desert inhabitants. To comply with sanitary ordinances, camel milk is pasteurized by procedures specified for bovine milk. It is widely accepted that milk composition might affect bacterial thermal death time (TDT). Camel and bovine milks markedly differ in their chemical composition, yet data regarding TDT values of bacteria in camel milk is missing. As a first step toward developing specific heat treatments appropriate for camel milk, TDT curves of Escherichia coli in artificially contaminated camel and cow milks have been compared. Heating the milks to temperatures ranging from 58 to 65 degrees C yields similar thermal death curves and derived D- and z-values. These findings suggest that, in this temperature range, E. coli might behave similarly in bovine and camel milk. Additional TDT studies of various pathogenic species in camel milk are required before establishing pasteurization conditions of camel milk.     

A Note on Scheduling Tall/Small Multiprocessor Tasks with Unit Processing Time to Minimize Maximum Tardiness

We study the scheduling situation where n tasks, subjected to release dates and due dates, have to be scheduled on m parallel processors. We show that, when tasks have unit processing times and either require 1 or m processors simultaneously, the minimum maximal tardiness can be computed in polynomial time. Two algorithms are described. The first one is based on a linear programming formulation of the problem while the second one is a combinatorial algorithm. The complexity status of this tall/small task scheduling problem P|r _i ,p _i =1, size _i {1,m}|T _max was unknown before, even for two processors.     

An efficient lattice-based phonetic search method for accelerating keyword spotting in large speech databases

This paper describes an algorithm for the reduction of computational complexity in phonetic search KeyWord Spotting (KWS). This reduction is particularly important when searching for keywords within very large speech databases and aiming for rapid response time. The suggested algorithm consists of an anchor-based phoneme search that reduces the search space by generating hypotheses only around phonemes recognized with high reliability. Three databases have been used for the evaluation: IBM Voicemail I and Voicemail II, consisting of long spontaneous utterances and the Wall Street Journal portion of the MACROPHONE database, consisting of read speech utterances. The results indicated a significant reduction of nearly 90 % in the computational complexity of the search while improving the false alarm rate, with only a small decrease in the detection rate in both databases. Search space reduction, as well as, performance gain or loss can be controlled according to the user preferences via the suggested algorithm parameters and thresholds.     

Greedy distributed optimization of multi-commodity flows

The multi-commodity flow problem is a classical combinatorial optimization problem that addresses a number of practically important issues of congestion and bandwidth management in connection-oriented network architectures. We consider solutions for distributed multi-commodity flow problems, which are solved by multiple agents operating in a cooperative but uncoordinated manner. We provide the first stateless greedy distributed algorithm for the concurrent multi-commodity flow problem with poly-logarithmic convergence. More precisely, our algorithm achieves ${1+\varepsilon}The multi-commodity flow problem is a classical combinatorial optimization problem that addresses a number of practically important issues of congestion and bandwidth management in connection-oriented network architectures. We consider solutions for distributed multi-commodity flow problems, which are solved by multiple agents operating in a cooperative but uncoordinated manner. We provide the first stateless greedy distributed algorithm for the concurrent multi-commodity flow problem with poly-logarithmic convergence. More precisely, our algorithm achieves 1+e{1+\varepsilon} approximation, with running time O(H· log^O(1)m· (1/e)^O(1)){O(H{\cdot} \log^{O(1)}m{\cdot} (1{/}\varepsilon)^{O(1)})} where H is the number of edges on any allowed flow-path. No prior results exist for our model. Our algorithm is a reasonable alternative to existing polynomial sequential approximation algorithms, such as Garg–K?nemann (Proceedings of the 39th Annual Symposium on Foundations of Computer Science, Palo Alto, CA, USA, pp. 300–309, 1998). The algorithm is simple and can be easily implemented or taught in a classroom. Remarkably, our algorithm requires that the increase in the flow rate on a link is more aggressive than the decrease in the rate. Essentially all of the existing flow-control heuristics are variations of TCP, which uses a conservative cap on the increase (e.g., additive), and a rather liberal cap on the decrease (e.g., multiplicative). In contrast, our algorithm requires the increase to be multiplicative, and that this increase is dramatically more aggressive than the decrease.     

Disengaged students and dialogic learning: the role of CSCL affordances

Only a few studies have dealt with the challenge of bridging the linguistic gap between the dialogic realm and the talk of disengaged students. Bridging this gap is particularly relevant to the CSCL community since one of its utmost aims is to promote the dialogic. This study aims to articulate how to harness the CSCL design and affordances to enhance dialogic pedagogy with disengaged students. Using temporal analysis of philosophical discussions for children, we focus on three disengaged 8th grade students participating in successive discussions mediated by a CSCL tool (Argunaut), and follow the way they talk with their peers in the classroom. The study shows the gradual emergence of the dialogic among those students. We describe the transition of their talk moves, from initially reproducing the way they talk to adopting dialogical norms. To explain this we conceptualize the notion of carriers of discursive norms and discuss its transformative role in dialogue. The dialogic transition was made possible by the pedagogical design and the design of the CSCL tools. These affordances allowed the students change the meaning of the conversational building blocks of space, silence, addressee, and the ethics of talk.     

Diagnosticity and pseudodiagnosticity.

Five experiments with 596 undergraduates contrasted Ss' intuitive evaluation of data for hypothesis testing with the Bayesian concept of diagnosticity. According to that normative model, the impact of a datum, D relative to a pair of hypotheses, H and H̄, is captured by its likelihood ratio, equal to P(D/H)/P(D/H̄). Results show that when Ss were asked to test the validity of H, only half expressed an interest in P(D/H). That proportion increased when they were asked to determine whether H or H̄ was true. That proportion decreased when the instructions more forcefully encouraged Ss to solicit only pertinent information. Thus Ss generally had a strong interest only in the conditional probability that mentioned the hypothesis (or hypotheses) that they were explicitly asked to test. When, however, they were presented with both components of the likelihood ratio, most Ss revealed a qualitative understanding of their meaning vis-à-vis hypothesis testing. Results are discussed in terms of the kinds of understanding that people might have for statistical principles. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Advantage of the presence of living dermal fibroblasts within in vitro reconstructed skin for grafting in humans

Methods for serial cultivation of human keratinocytes can provide large quantities of epidermal cells, which have the potential of restoring the vital barrier function of the epidermis in extensive skin defects such as burns. To investigate the value of combining an epidermis with a dermal component, fibroblasts originated from the superficial dermis were used to seed a collagen lattice as described by E. Bell (dermal equivalent). Beginning in 1981, we grafted 18 patients (burns and giant nevi) using 35 grafts 10 x 10 cm in size. In the course of this work, the original technique was modified and improved as experience was gained. We began by using small skin biopsy samples as a source of keratinocytes cultured on a dermal equivalent before grafting in a one-step procedure, but this gave poor cosmetic results, because of a nonhomogeneous epidermalization. We then chose to cover the graft bed using a two-step procedure. The first step consisted of grafting a dermal equivalent to provide a dermal fibroblast-seeded substrate for subsequent in vivo epidermalization by cultured epidermal sheets. Whatever the epidermalization technique used, a living dermal equivalent applied to the graft bed was found to reduce pain, to provide good hemostasis, and to improve the mechanical and cosmetic properties of the graft. A normal undulating dermal-epidermal junction reappeared by 3 to 4 months after grafting and elastic fibers were detectable 6 to 9 months after grafting. As a result of the biosynthesis of these products, the suppleness (e.g., elasticity) of the grafts was closer to that of normal skin than the cicatricial skin usually obtained with epidermal sheets grafted without the presence of living dermal cells. This rapid improvement of the mechanical properties of the graft could be attributed to the presence of fibroblasts cultured from the dermis and seeded into the collagen matrix.     

Evolving Judgments of Terror Risks: Foresight, Hindsight, and Emotion.

The authors examined the evolution of cognitive and emotional responses to terror risks for a nationally representative sample of Americans between late 2001 and late 2002. Respondents' risk judgments changed in ways consistent with their reported personal experiences. However, they did not recognize these changes, producing hindsight bias in memories for their judgments. An intensive debiasing procedure failed to restore a foresightful perspective. A fear-inducing manipulation increased risk estimates, whereas an anger-inducing manipulation reduced them-both in predictions (as previously observed) and in memories and judgments of past risks. Thus, priming emotions shaped not only perceptions of an abstract future but also perceptions of a concrete past. These results suggest how psychological research can help to ensure an informed public. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The need for a global talking cure for practitioners: Reply to Ghannam (2005).

Replies to comments made by J. Ghannam (see record 2005-01622-015) on the current author's original article (see record 2003-09630-009). Ghannam's comment reveals just how necessary a global "talking cure" is, not just for people outside the field of psychoanalysis but for practitioners within it and related fields as well. One challenge for an international psychoanalysis with regard to the political scene is to devise guidelines that will help analysts to deal with the anger that leads less to truth than to its retreat. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Medium Time Metric: High Throughput Route Selection in Multi-rate Ad Hoc Wireless Networks

Modern wireless devices, such as those that implement the 802.11abg standards, utilize multiple transmission rates in order to accommodate a wide range of channel conditions. The use of multiple rates presents a significantly more complex challenge to ad hoc routing protocols than the traditional single rate model. The hop count routing metric, which is traditionally used in single rate networks, is sub-optimal in multi-rate networks as it tends to select short paths composed of maximum length links. In a multi-rate network, these long distance links operate at the slowest available rate, thus achieving low effective throughput and reduced reliability due to the low signal levels. In this work we explore the lower level medium access control and physical phenomena that affect routing decisions in multi-rate ad hoc networks. We provide simulation results which illustrate the impact of these phenomena on effective throughput and show how the traditional minimum hop routing strategy is inappropriate for multi-rate networks. As an alternative, we present the Medium Time Metric (MTM) which avoids using the long range links often selected by shortest path routing in favor of shorter, higher throughput, more reliable links. Our experimental results with 802.11 g radios show that the Medium Time Metric achieves significantly higher throughput then alternative metrics. We observed up to 17 times more end-to-end TCP throughput than when the Min Hop or ETX metrics were used. Baruch Awerbuch is currently a professor at the Computer Science Dept. at Johns Hopkins University. His current Research interests include: Security, Online Algorithms, Distributed and Peer-to-Peer Systems, Recommendation Systems, and Wireless Networks. Baruch Awerbuch has published more than 100 papers in journals and refereed conferences in the general area of design and analysis of online algorithms, combinatorial and network optimization, distributed algorithms, learning, fault tolerance, network architecture, and others. Baruch Awerbuch is a co-director of the JHU Center for Networks and distributed systems http://www.cnds.jhu.edu. He is supervising the Archipelago project http://www.cnds.jhu.edu/archipelago whose goal is developing WiFi (IEEE 802.11 based) multi-hop wireless network based on novel rerouting algorithms. Dr. Awerbuch served as a member of the Editorial Board for Journal of Algorithms, Wireless Networks and Interconnection Networks. He was a program chair of the 1995 ACM Conference on Wireless Computing & Communication and a member of the program committees of the 2004 ACM Mobihoc, as well as PC member ACM PODC Principles of Distributed Computing (PODC) Conference in 1989 and of the Annual ACM STOC (Symposium on Theory of Computing) Conference in 1990 and 1991. Web: http://www.cs.jhu.edu/~baruch David Holmer received his B.S. in electrical engineering and MSE in computer science from the Johns Hopkins University in 2001 and 2002. He is now a Ph.D. candidate in the Department of Computer Science at Johns Hopkins University, and a research assistant in the Wireless Communication Group. The theme of his research is the development of deployable high performance ad hoc networking technology. As a result, his interests span many aspects of wireless networking including: routing, medium access control, physical layer properties and simulation, security, and energy efficiency. Herbert Rubens is a Ph.D. candidate in the Computer Science Department at the Johns Hopkins University (JHU) in Baltimore, Maryland. He is a member of the Wireless Communication Group, and specializes in multi-hop ad hoc protocol design. He has designed innovative mechanisms allowing power efficiency, high scalability, and efficient resource allocation in wireless networks. He obtained his B.Sc. and Masters Degree in computer science from Johns Hopkins University in 2001 and 2002 respectively. His research interests include ad hoc routing, medium access control, network security, and distributed algorithms.