Evaluation of Techniques for Detection of Carbapenem-Resistant Klebsiella pneumoniae in Stool Surveillance Cultures

Screening for gastrointestinal colonization with multidrug-resistant nosocomial pathogens is an important component of infection control protocols. In the New York City region, carbapenem-resistant Klebsiella pneumoniae strains, which harbor the KPC carbapenem-hydrolyzing β-lactamase, have rapidly emerged. The potential utility of screening medium, which involved using 10-μg imipenem disks, was investigated. The method of placing a sample from a fecal surveillance culture into broth containing an imipenem disk appeared to have the greatest sensitivity for detecting KPC-producing K. pneumoniae. Gastrointestinal colonization with two other carbapenem-resistant nosocomial pathogens, Pseudomonas aeruginosa and Acinetobacter baumannii, was also detected using this method. Placing fecal surveillance specimens into broth containing an imipenem disk is an easy method for screening samples for carbapenem-resistant nosocomial pathogens

Modeling Context-Sensitive, Dynamic Activity Travel Behavior by Linking Short- and Long-Term Responses to Accumulated Stress

As existing activity-based models of travel demand simulate activity travel patterns for a typical day, dynamic models simulate behavioral response to endogenous or exogenous change along various time horizons. Prior research predominantly addressed a specific kind of change, which usually affected a specific time horizon. In contrast, the current study aims to develop a dynamic model of activity travel decisions that links short-and long-term adaptation decisions in a hierarchical manner. Specifically, this study focuses on the bottom-up process of influence, in which problems with rescheduling on a daily basis may induce a long-term change. The authors assume that travelers will first explore short-term adjustments of their habitual activity travel patterns so as to cope with change and increasing stress. Only when travelers recognize that such adaptation strategies are ineffective will they consider long-term decisions. The proposed framework integrates three key concepts: aspiration, activation, and expected utility. Moreover, both rational and emotional mechanisms are taken into account. The study demonstrates model properties by using numerical simulation. Individual travelers are represented as agents, each with their cognition of the environment, habits, preferences, and aspirations. The results offer insight into the dynamics of traveler learning-adaptation and into the evolution of long-term decisions

Choque térmico em filtros cerâmicos do sistema Al2O3-SiC Thermal shock on ceramic filters in the system Al2O3-SiC

Em diversas aplicações as cerâmicas celulares são submetidas a tensões térmicas severas, tal como na filtração de metais fundidos. Contudo, há poucos estudos sobre o desempenho ao choque térmico destes materiais. Uma das razões é que a metodologia para análise desta classe de materiais deve ser distinta daquela utilizada para os materiais cerâmicos densos. Isto porque no caso dos materiais celulares para filtração de metais fundidos o meio causador do choque térmico infiltra-se rapidamente na estrutura reticular de poros, reduzindo o gradiente de temperatura entre a superfície externa e a do interior do corpo. Neste contexto, a proposta do presente trabalho é verificar os efeitos de algumas propriedades dos filtros cerâmicos em seu comportamento mecânico durante testes de choque térmico em água. As propriedades consideradas são a permeabilidade, a condutividade térmica e a área superficial específica dos filtros. Para isto foram utilizados os filtros cerâmicos do sistema de Al2O3-SiC de 8, 10, 20 e 30 ppi (poros por polegada linear).<br>In many applications, open-cell ceramics are expected to undergo severe thermal stresses, for instance, in their use as molten metal filters. However, only a few studies have considered the thermal shock behavior of these materials. One of the main reasons is the theoretical approach used for dense ceramics which may not be valid for porous materials. In this context, the aim of this work is to analyze the effects of permeability, specific surface area and thermal conductivity on the mechanical behavior of ceramic filters subjected to water quenching tests. Al2O3-SiC filters with nominal cell sizes, expressed as the number of pores per linear inch (ppi), ranged from 8 to 30 ppi were used in the experimental tests