某背靠背换流站不同负荷状态下工频电磁场检测分析

采用典型抽样方法，选取某±500 kV背靠背换流站为研究对象，依据《工作场所物理因素测量 第3部分：1 Hz~100 kHz电场和磁场》（GBZ/T 189.3—2018）在满负荷和低负荷状态下对工频电场和磁场进行检测。结果显示，满负荷和低负荷状态下工频电场强度分别为0.035~16.815 kV/m和0.009~14.750 kV/m，M分别为3.706 kV/m和3.185 kV/m，分别有11（20.8%）和6（11.3%）个点电场强度>10 kV/m，超过国际非电离辐射防护委员会（ICNIRP）2010年规定的接触限值要求。两种状态下磁场强度分别为0.24~51.91 μT和0.05~68.09 μT，M值分别为3.38 μT和1.41 μT，均符合ICNIRP 2010的限值要求。作业人员工频电场强度8 h时间加权平均值分别为3.436 kV/m和2.799 kV/m，符合《工作场所有害因素职业接触限值 第2部分：物理因素》（GBZ 2.2—2007）的要求。满负荷状态下电场和磁场强度测量值均高于低负荷状态下相应测量值，差异有统计学意义（P<0.01），且满负荷状态下工频电场≥5 kV/m的检测点超标率高于低负荷状态（P<0.05）。该背靠背换流站作业人员在满负荷状态下接触的工频电场强度较高，巡检时应做好个人防护。     

Formation of methylmercury in the marine sediment under in vitro conditions

The purpose of this study was to find out whether there is an appreciable conversion of inorganic mercury into methylmercury in the marine bottom sediment. Samples were taken from the Eastern Mediterranean coast, in the Haifa Bay area. HgCl₂ in various concentrations was added to flasks containing samples of sterile or nonsterile bottom sediment and growth medium, and the flasks were incubated under aerobic or anaerobic conditions, for different time intervals. We found that indeed methylmercury was formed, probably by microbial action (since no methylmercury was detected in any of the flasks containing sterile sediment samples). Several types of bacteria which could tolerate considerable concentrations of mercury were isolated, and each type was innoculated into flasks containing medium and a sterile sediment sample. Methylmercury was later found in the latter flasks also.     

Allostatic load and work conditions

Adverse work characteristics and poor social support have been associated with an increased risk for cardiovascular disease and other adverse health outcomes in otherwise apparently healthy adults. We undertook a cross-sectional study to evaluate the relationship between objective health status and work characteristics in industrial workers in Germany. Volunteers (n=324) were recruited from a representative random sample (n=537) of employees of an airplane manufacturing plant. Psychosocial work characteristics were assessed by the 52-item, 13-subscale salutogenetic subjective work analysis (SALSA) questionnaire, which assesses potentially salutogenic and pathogenic conditions. Factor analysis revealed three factors: decision latitude, job demands and social support. Biological health status was determined by the revised allostatic load score with 14 components: body-mass index, waist-to-hip ratio; systolic and diastolic blood pressure; plasma levels of C-reactive protein (CRP), tumor-necrosis factor-alpha, HDL, cholesterol, dehydroepiandrosterone sulfate; glycosylated hemoglobin; urinary cortisol, epinephrine, norepinephrine, and albumin. Score points were given for values in the high-risk quartile (maximum=14). General linear models revealed that older individuals and men had significantly higher allostatic load scores than younger participants or women. Of the SALSA factors, only job demands related significantly to allostatic load. The effect of demands was stronger in older individuals. Post-hoc analysis showed possible positive associations between high job demands and blood pressure or CRP, and between low social support and nocturnal excretion of cortisol or plasma levels of CRP. We conclude that this cross-sectional study on industrial employees found a weak association between a health summary score based on objective medical data and self-reported adverse work characteristics.     

Social course patterns of urban dwellers with tuberculosis under fragile living conditions in Tokyo, Japan

BACKGROUND: People under fragile-living conditions show a high rate of interruption of tuberculosis treatment. We examined the social courses of fragile-living urban dwellers with tuberculosis without customary and regular access to a conventional residence and investigated the factors associated with interruption of treatment. METHODS: One hundred and nineteen tuberculosis patients without customary and regular access to a conventional residence who were discharged from a hospital with the largest number of tuberculosis beds in Tokyo between January 1998 and October 2000 were followed up. The associations between demographic, social, and clinical characteristics and interruption of treatment were examined. RESULTS: The subjects (mean age, 51.2 years) were followed up for a median of 342 days. The percentage of cases of interruption of treatment during inpatient care among patients with alcohol problems (56%) was significantly higher than that among patients without such problems (11%). The proportion of cases of interruption of treatment during outpatient care among patients who were literally homeless before admission (40%) was significantly higher than that in others (5%), and that among those who used transient hostels after the initial inpatient treatment (55%) was significantly higher than that in others (4%). The prevalence of drug resistance was higher in cases with than without a history of tuberculosis treatment (P<0.05). CONCLUSIONS: Factors associated with interruption of tuberculosis treatment in patients under fragile-living conditions were identified. Interruption during inpatient care was significantly associated with alcohol problems, and interruption during outpatient care was significantly associated with the use of transient hostels.     

Bacterial load of cockroaches in relation to urban environment.

Sanitation is an important problem in relation to the control of pests in urban environments. This investigation analysed the potential risk related to the presence of cockroaches and their capacity for disseminating bacteria in six different types of buildings: hospital nursing area and out-patient area, swimming-pool pool-side and toilet area, low-income flats and food-handling places. Fifty-six species of bacteria were identified from 157 samples, 14 of these have previously been reported as potentially pathogenic for man and vertebrates. Similarities were found between samples collected in (a) the hospital out-patient area and food-handling establishments and (b) the hospital nursing area and flats. Pool-sides possessed a poorer bacterial flora. There was a greater bacterial specific diversity in food-handling establishments, flats and swimming-bath toilet area. Enterobacter cloacae. Klebsiella pneumoniae and Klebsiella oxytoca were dominant species in flats and the hospital nursing area. Therefore, cockroaches can play a role in disseminating bacteria, which they can carry passively on their cuticle.     

Potential health impact of ultrafine particles under clean and polluted urban atmospheric conditions: a model-based study

The main goal of this study was to improve the knowledge of ultrafine particle number distributions in large urban areas and also to call the attention to the importance of these particles on assessing health risks. Measurements of aerosol size distributions were performed during 2 weeks, with distinct pollutant concentrations (polluted and clean periods), on the rooftop of a building located in downtown of the megacity of São Paulo, Brazil. CO, NO₂, PM₁₀, SO₂, and O₃ concentrations and meteorological variables were also used. Aerosol size distribution measurements showed that geometric mean diameters of the size spectra in the polluted period are on average considerably larger than those in the clean one. Besides the fact that total number of ultrafine particles did not show significant differences, during the polluted period, geometric mean diameter was larger than during the clean one. The results of a mathematical model of particle deposition on human respiratory tract indicated a more significant effect of smaller particles fraction of the spectra, which predominate under clean atmospheric conditions. The results also indicated that urban environmental conditions usually considered good for air quality, under the criteria of low mass concentration, do not properly serve as air quality standard to very small particles. In the size range of ultrafine particles, this traditional clean atmospheric condition can offer a strong risk to pulmonary hazards, since the cleansing of the atmosphere creates good conditions to increase the concentration of nucleation mode particles.     

Perspectives on urban conditions and population health

The majority of the world's population will live in cities in the next few years and the pace of urbanization worldwide will continue to accelerate over the coming decades. While the number of megacities is projected to increase, the largest population growth is expected to be in cities of less than one million people. Such a dramatic demographic shift can be expected to have an impact on population health. Although there has been historic interest in how city living affects health, a cogent framework that enables systematic study of urban health across time and place has yet to emerge. Four alternate but complementary approaches to the study of urban health today are presented (urban health penalty, urban health advantage, urban sprawl, and an integrative urban conditions model) followed by three key questions that may help guide the study and practice of urban health in coming decades.     

厦门市城区居民膳食血糖负荷和膳食胰岛素负荷的 现况调查

摘要:目的　了解厦门市城区居民碳水化合物消费情况及膳食血糖负荷及膳食胰岛素负荷的现状,调查膳食血糖负荷及膳食胰岛素负荷与生化指标。方法　根据全国营养调查方案,2010年10-12月对厦门市城区的6个社区居委会成年居民进行调查,采用连续3 d 24 h回顾法对其中的291人进行膳食调查、身体测量及生化指标测量;根据膳食血糖生成指数（GI）和碳水化合物摄入量计算膳食血糖负荷（GL）;根据膳食胰岛素指数（II）和能量及食用频率计算膳食胰岛素负荷（IL）。结果　被调查的厦门市城区成年居民的平均膳食血糖指数为75.2;平均膳食血糖负荷为179.1;平均膳食胰岛素指数为30.4,平均膳食胰岛素负荷为247.2。粮谷类对膳食GL、IL的贡献达92.0%、83.1%。不同GL、IL水平的被调查人群的身体测量及生化指标间的差异无统计学意义;通过多元线性回归分析并未发现膳食GI、GL、II、IL与糖尿病的患病风险有明显的相关性。结论　粮谷类食物是厦门市城区居民膳食GL、IL的主要来源,低膳食GL的人群粮谷类消费低,脂肪消费高,膳食结构不合理;并未发现膳食GL、IL与身体测量及生化指标之间的联系。     

Animal experiment studies of chronic thiamine deficiency. Changes in carbohydrate and amino acid metabolism under resting and load conditions

The metabolic effects of thiamine deficiency on the metabolism of lactate, acid-base and amino acids were evaluated both with and without muscular exercise in a controlled animal experiment. Thiamine deficiency - in good correlation with its biologic halftime and also with reports in the literature - caused with a latency of 17-56 days and statistically proven in parallel the following effects: hyperlactemia; in comparison to controls elevated plasma concentrations of threonine, alanine, glutamic acid, glutamine, histidine, methionine, taurine, valine, isoleucine and leucine; distinctly lowered - also in comparison to controls - plasma concentrations of arginine and tryptophan. Furthermore, in the thiamine deficient rats predetermined muscular exercise caused the following effects, also occurring concomitantly: life threatening lactacidosis; marked - statistically prover - disturbance of the homeostasis of alanine, glycine, methionine and arginine; distinctly - and statistically significant - elevated plasma concentration of proline; statistically significantly lowered plasma concentrations of taurine. The reasons for all these changes under thiamine deficiency is most likely a metabolic one primarily due to a disturbance of the utilization of pyruvate in the liver. An additional disturbance of both the transsulfuration pathway and the Krebs-Henseleit-cycle seems probable. The physiologic regulation of pyruvate, lactate, alanine, serine and tyrosine during muscular exercise in correlation to the controls is being discussed.     

Cardiovascular risk in operators under radiofrequency electromagnetic radiation

The aim of the study was to assess the long-term effects of radiofrequency electromagnetic radiation (EMR) on the cardiovascular system. Two groups of exposed operators (49 broadcasting (BC) station and 61 TV station operators) and a control group of 110 radiorelay station operators, matched by sex and age, with similar job characteristics except for the radiofrequency EMR were studied. The EMR exposure was assessed and the time-weighted average (TWA) was calculated. The cardiovascular risk factors arterial pressure, lipid profile, body mass index, waist/hip ratio, smoking, and family history of cardiovascular disease were followed. The systolic and diastolic blood pressure (SBP and DBP), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly higher in the two exposed groups. It was found that the radiofrequency EMR exposure was associated with greater chance of becoming hypertensive and dyslipidemic. The stepwise multiple regression equations showed that the SBP and TWA predicted the high TC and high LDL-C, while the TC, age and abdominal obesity were predictors for high SBP and DBP. In conclusion, our data show that the radiofrequency EMR contributes to adverse effects on the cardiovascular system.     

An exploratory study of cognitive load in diagnosing patient conditions.

OBJECTIVE: To determine whether the ways in which information is presented to physicians will improve their ability to respond in a timely and accurate manner to acute care needs. The forms of the presentation compared traditional textual, chart and graph representations with equivalent symbolic language representations. To test this objective, our investigation involved two studies of interpreting patient conditions using two forms of information representation. The first assessed the level of cognitive effort (the outcome variable is known as cognitive load), and the second assessed the time and accuracy outcome variables. PARTICIPANTS: Our investigation consisted of two studies, the first study involved 3rd and 4th year medical students, and the second study involved three board certified physicians who worked in an intensive care unit of a metropolitan hospital. DESIGN: The first study utilized an all-within-subject design with repeated measures, where pretests were utilized as control covariate for prior learning and individual differences. The second study utilized a random sampling of records analyzed by two physicians and qualitatively evaluated by board-certified intensivists. RESULTS: The first study indicated that the cognitive load to interpret the symbolic representation was less than those presented in the more traditional textual, chart and graphic form. The second study suggests that experienced physicians may react in a more timely fashion with at least the same accuracy when the symbolic language was used than with traditional charts and graphs. CONCLUSIONS: The ways in which information is presented to physicians may affect the quality of acute care, such as in intensive, critical and emergency care units. When information can be presented in symbolic form, it may be cognitively processed more efficiently than when it is presented in the usual textual and chart form, potentially lowering errors in diagnosis and increasing the responsiveness to patient conditions.