Reducing back stress to nursing personnel: an ergonomic intervention in a nursing home

A prospective epidemiologic study was conducted in two units (140 beds and 57 nursing assistants) of a nursing home to demonstrate the efficacy of an ergonomic intervention strategy to reduce back stress to nursing personnel. The total programme involved the following: determining patient handling tasks perceived to be most stressful by the nursing assistants (NAs); performing an ergonomic evaluation of these tasks; and conducting a laboratory study to select patient transferring devices perceived to produce less physical stress than existing manual patient-handling methods. The intervention phase included training NAs in the use of these devices, modifying toilets and shower rooms, and applying techniques to patient care. Immediately after completing the intervention programme, a post-intervention analysis (which lasted eight months in unit 1 and four months in unit 2) was performed.

A biomechanical evaluation of the physical demands required to perform stressful patient-handling tasks showed that the mean compressive force on the L5/S1 disc, the mean hand force required to make a transfer, and the strength requirements (expressed as percentage female population capable) were 1964?N, 122?N, and 83% after intervention as compared to 4751?N, 312?N, and 41% before intervention. Subjectively, the mean rating of perceived exertion was less than ‘very light’ after intervention as compared to between ‘somewhat hard’ and ‘hard’ before intervention. Overall, the mean acceptability rates for the walking belt and the mechanical hoist were 81% and 87% for patient transfers. The incidence rate for back injuries prior to the intervention, 83 per 200 000 work-hours, decreased to 47 per 200 000 work-hours after the intervention. There were no injuries resulting in lost or restricted work days during the last four months of the post-intervention. It is concluded that an appropriate ergonomic intervention programme offers great promise in reducing physical stress and risk of low-back pain to nursing personnel. However, large-scale studies in different nursing homes are needed to confirm the above findings.     

Indoor exposure to particulate matter and the incidence of acute lower respiratory infections among children: A birth cohort study in urban Bangladesh

Approximately half of all children under two years of age in Bangladesh suffer from an acute lower respiratory infection (ALRI) each year. Exposure to indoor biomass smoke has been consistently associated with an increased risk of ALRI in young children. Our aim was to estimate the effect of indoor exposure to particulate matter (PM_2.5) on the incidence of ALRI among children in a low‐income, urban community in Bangladesh. We followed 257 children through two years of age to determine their frequency of ALRI and measured the PM_2.5 concentrations in their sleeping space. Poisson regression was used to estimate the association between ALRI and the number of hours per day that PM_2.5 concentrations exceeded 100 μg/m³, adjusting for known confounders. Each hour that PM_2.5 concentrations exceeded 100 μg/m³ was associated with a 7% increase in incidence of ALRI among children aged 0–11 months (adjusted incidence rate ratio (IRR) 1.07, 95% CI 1.01–1.14), but not in children 12–23 months old (adjusted IRR 1.00, 95% CI 0.92–1.09). Results from this study suggest that reducing indoor PM_2.5 exposure could decrease the frequency of ALRI among infants, the children at highest risk of death from these infections.     

网络连通性问题的快速解法

提出了基于关联矩阵求解网络连通性问题的基本原理,并且说明了该算法的快速技术和实现方法,该算法既可以通过汇编语言或高级语言编程实现,也可以由单片机系统或ASIC等硬件方法实现,特别适用于实时求解.     

Priorities of pedestrian protection—A real-life study of severe injuries and car sources

The aim of this study was to aid the optimisation of future, vehicle based, pedestrian injury countermeasures. The German In-Depth Accident Study (GIDAS) database was queried for pedestrians impacted by the front of a passenger car or van. A total of 1030 cases from 1998 to 2008 were studied including 161 severely (AIS3+) injured pedestrians. Considering the severe injuries, the most frequent injury mechanisms were “leg-to-front end”, “head-to-windscreen area”, “chest-to-bonnet area”, and “chest-to-windscreen area”. For children, a “head-to-bonnet area” impact was the second most common source of injury. With safety systems targeting these five injury mechanisms, 73% (95% confidence interval [CI], 65–81%) of the severely injured pedestrians would be provided protection from all of their vehicle-induced severe injuries. Omitting the windscreen area, this figure is decreased to 44% (CI, 36–53%). Furthermore, 31% of the surviving pedestrians were estimated to sustain a permanent medical impairment at any level. For more severe impairment, head was the dominating body region. The study shows that when developing countermeasures for the windscreen area to mitigate head injuries, attention should be paid to the structural parts of the windscreen area with a special focus on brain injuries. Finally, the incidence and risk of severe injury were derived as functions of impact speed for different body regions and injury sources.     

Correctness criteria of some algorithms for uncertain reasoning using Incidence Calculus

Incidence Calculus is a technique for associating uncertainty values with logical sentences. These uncertainty values are called incidences and they are sets of points, which may be thought of as representing equivalence classes of situations, Tarskian models, or possible worlds. Incidence Calculus was originally introduced in [1]. Incidence Calculus was designed to overcome various inherent problems with purely numeric mechanisms for uncertain reasoning [2]. In particular, incidences can represent the dependence between sentences, which numbers cannot, and hence Incidence Calculus can provide genuine, probabilistic reasoning. In this paper we prove soundness and completeness results for some algorithms introduced in [1] and hence satisfy some of the correctness criteria for Incidence Calculus. These algorithms can be used for probabilistic reasoning and to check the consistency of the subjective probabilities of sentences.     

Information-theoretic bounds for authentication schemes

Consider the situation whereby each member of a sequence of n distinct messages from a finite source space is provided with an authentication check, generated using one and the same encoding rule selected from a finite space of such rules. Let P(n) be the expected probability that a spoofer, who observes such a sequence of messages and their corresponding authentication checks, but does not know the encoding rule in advance, succeeds in generating the correct authentication check for a different message in the source space. The purpose of this paper is to derive a lower bound for the average P _Nof the probabilities P(0), P(1),...;, P(N) in terms of the entropy of the space of encoding rules, and to derive necessary and sufficient conditions which the encoding scheme must satisfy in order to ensure that this bound cannot be exceeded.     

弹性波理论研究──关于球面波首项(Ⅰ)

本文推导了球面波在弹性介质中传播的首项公式，包括直达波，反射波和透射波的首项。通过对球面波分解。用柱面波合成球面波；在界面上由压力和速度连续条件，给出了人射波，反射波和透射波的表达式；对汉格尔函数用大自变量展开，用最陡下降法分别求出这三种波的首项解析表达式。