Polysomnographic screening of infants at risk for SIDS

The authors present a Sudden Infant Death Syndrome prevention program. The study analyses the data of 92 children having participated in the complex prevention program, including polysomnography, between May 1997 and February 1998. The role of polysomnography and its use as a clinical method is described through the statistical analysis of the results of the study.     

Discriminatory processor sharing queues with stationary ergodic service times and the performance of TCP in overload

In a recent paper, Bonald and Roberts (2001) [6] studied non-persistent TCP connections in transient overload conditions, under the assumption that all connections have the same round-trip times. In this paper our goal is to develop theoretical tools that will enable us to relax this assumption and obtain explicit expressions for the rate of growth of the number of connections at the system, the rate at which TCP connections leave the system, as well as the time needed for the completion of a connection. To that end, we model the system as a discriminatory processor sharing (DPS) system which we analyze under very mild assumptions on the probability distributions related to different classes of arrivals: we only assume that the arrival rates of connections exist, and that the amount of information transmitted during a connection of a given type forms a stationary ergodic sequence. We then proceed to obtain explicit expressions for the growth rate of the number of connections at the DPS system for several specific probability distributions. We check through simulations the applicability of our queueing results for modeling TCP connections sharing a bottleneck.     

Multiple roles, social networks, and women's well-being.

In contrast to earlier approaches to the study of multiple roles, our research was concerned with the frequency and conditions under which both positive and negative outcomes occur. Using data from a random sample of 235 married female nurses, we focused on marital and job satisfaction as important criteria of success in managing multiple roles. In the first phase of the research, a cluster analysis identified five different profiles of marital and job satisfaction. Of the two most positive profiles, one was defined by high scores in both areas, the other by high job satisfaction but only moderate marital satisfaction. In two other profiles, women were very dissatisfied with one role and at best moderately satisfied with the other. In the second phase, the profiles were found to be meaningfully associated with measures of psychological symptomatology and overall life satisfaction. The third phase considered how the profiles were linked to measures of social support and social rejection provided by five key network members. The strongest univariate profile discriminator was the level of work rejection from the spouse. A discriminate function analysis revealed that the level of spouse's work rejection was even more powerful when it was compared to the level of work rejection received from the next closest family member (typically the mother). (53 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does hepatitis G virus cause significant clinical liver disease?

Regarding the newly discovered hepatitis G virus (HGV), little is known about its relation to the cause and clinical significance of acute and chronic liver disease and hepatocellular carcinoma. Lacking a reliable serum immunoassay, the only method available for detecting the viral RNA in patients consists of the rather costly and time consuming RT-PCR. HGV has a worldwide distribution with up to 5% voluntary and 12.9% commercial blood donors infected, yet it appears to be asymptomatic. Moreover, HGV is frequently found as a coinfection with HCV or, to a lesser extent, HBV with symptoms tending to follow the patterns known for HCV or HBV infection, respectively. Being a blood-borne virus, it is most prevalent among members of high risk groups, such as IVDUs, patients on hemodialysis, recipients of blood and blood products and patients infected with HCV, HBV, or HIV, HGV can be parenterally, vertically, or sexually transmitted and after prolonged exposure, the virus may be eliminated by the patient's immune response. As yet, no unambiguous evidence exists regarding HGV's role in causing acute or chronic liver disease and, apart from a few isolated reports to the contrary, the infections appear rather mild. Therefore, more studies are required before a decision can be made whether to routinely screen blood donors for the presence of HGV RNA.     

Advancements in the Field of Direct Steam Generation in Linear Solar Concentrators—A Review

Direct steam generation in parabolic trough or linear Fresnel collectors represents one interesting technological option for concentrating solar electricity production. Today's state of the art characterized by the first commercial plants in operation is a result of more than 20 years of intensive research on this topic. This article provides a review on the key results from research that includes physical effects like heat transfer and pressure drop in horizontal boiler tubes, plant layout considerations, and thermal storage options. An overview on test and demonstration facilities as well as on commercial plants is given, leading to an outlook on the next generation of direct steam generation systems.     

Hydrogen sensor based on a graphene – palladium nanocomposite

A composite material was prepared from graphene and palladium nanoparticles (PdNP) by layer-by-layer deposition on gold electrodes. The material was characterized by absorption spectroscopy, scanning electron microscopy, Raman spectroscopy and surface plasmon resonance. Cyclic voltammetry demonstrated the presence of electrocatalytic centers in the palladium decorated graphene. This material can serve as a sensor material for hydrogen at levels from 0.5 to 1% in synthetic air. Pure graphene is poorly sensitive to hydrogen, but incorporation of PdNPs increases its sensitivity by more than an order of magnitude. The effects of hydrogen, nitrogen dioxide and humidity were studied. Sensor regeneration is accelerated in humid air. The sensitivity of the nanocomposite depends on the number of bilayers of graphene–PdNPs.