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51.
This paper presents the evaluation results of protective performance of the respirators (full face supplied-fresh air respirators and half-mask active charcoal filter) and personal exposure measurement (Infacepiece sampling) in a Belgian viscose rayon factory. With in-facepiece sampling technique and personal sampling method, we measured the CS2 concentrations inside and outside of the different respirators. We found two kinds of the respirators have significant effect on decreasing the CS2 exposure level for the subject, especially for the spinners. Full face supplied-fresh air respirator have good protective effect for the spinners and have limit protection for the high exposure job although the PF value is more than 10. It still need to improve more. In-facepiece sampling for all the subjects exposed to CS2 in the factory found most subjects have exposed to low CS2 concentration, most exposure levels were under the control range, but sulfuror are high exposure, the exposure level is higher than ACGIH TLV value. Supported by the Belgian Science Research Office, (DWTC, Belgium) under contact number ST/02/034 Tan Xiaodong: born in 1963, Associate professor, Medical doctor and Master of Public Health  相似文献   
52.
Bosonic modes have wide applications in various quantum technologies,such as optical photons for quantum communication,magnons in spin ensembles for quantum inf...  相似文献   
53.
孤波物理学     
自从1834年第一次观察到孤波现象以来,除了相关的数学理论得到了迅速发展之外,在物理学的多个领域中,孤波的理论和应用都得到了广泛的和深人的研究。其中包括流体动力学、光纤通讯、固态物理以及生物大分子动力学等诸方面,都发展了全新的观点和新的思考方式,促进了非线性现象的深人研究和多个前沿研究领域的形成。  相似文献   
54.
Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15 days. Here we report a system of three Neptune-mass planets with periods of 8.67, 31.6 and 197 days, orbiting the nearby star HD 69830. This star was already known to show an infrared excess possibly caused by an asteroid belt within 1 au (the Sun-Earth distance). Simulations show that the system is in a dynamically stable configuration. Theoretical calculations favour a mainly rocky composition for both inner planets, while the outer planet probably has a significant gaseous envelope surrounding its rocky/icy core; the outer planet orbits within the habitable zone of this star.  相似文献   
55.
Experimental and theoretical study of mitotic spindle orientation   总被引:1,自引:0,他引:1  
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56.
In 2007, the Intergovernmental Panel on Climate Change highlighted an urgent need to assess the responses of marine ecosystems to climate change. Because they lie in a high-latitude region, the Southern Ocean ecosystems are expected to be strongly affected by global warming. Using top predators of this highly productive ocean (such as penguins) as integrative indicators may help us assess the impacts of climate change on marine ecosystems. Yet most available information on penguin population dynamics is based on the controversial use of flipper banding. Although some reports have found the effects of flipper bands to be deleterious, some short-term (one-year) studies have concluded otherwise, resulting in the continuation of extensive banding schemes and the use of data sets thus collected to predict climate impact on natural populations. Here we show that banding of free-ranging king penguins (Aptenodytes patagonicus) impairs both survival and reproduction, ultimately affecting population growth rate. Over the course of a 10-year longitudinal study, banded birds produced 41% [corrected] fewer chicks and had a survival rate 16 percentage points [corrected] lower than non-banded birds, demonstrating a massive long-term impact of banding and thus refuting the assumption that birds will ultimately adapt to being banded. Indeed, banded birds still arrived later for breeding at the study site and had longer foraging trips even after 10?years. One of our major findings is that responses of flipper-banded penguins to climate variability (that is, changes in sea surface temperature and in the Southern Oscillation index) differ from those of non-banded birds. We show that only long-term investigations may allow an evaluation of the impact of flipper bands and that every major life-history trait can be affected, calling into question the banding schemes still going on. In addition, our understanding of the effects of climate change on marine ecosystems based on flipper-band data should be reconsidered.  相似文献   
57.
Recurrent chromosomal translocations underlie both haematopoietic and solid tumours. Their origin has been ascribed to selection of random rearrangements, targeted DNA damage, or frequent nuclear interactions between translocation partners; however, the relative contribution of each of these elements has not been measured directly or on a large scale. Here we examine the role of nuclear architecture and frequency of DNA damage in the genesis of chromosomal translocations by measuring these parameters simultaneously in cultured mouse B lymphocytes. In the absence of recurrent DNA damage, translocations between Igh or Myc and all other genes are directly related to their contact frequency. Conversely, translocations associated with recurrent site-directed DNA damage are proportional to the rate of DNA break formation, as measured by replication protein A accumulation at the site of damage. Thus, non-targeted rearrangements reflect nuclear organization whereas DNA break formation governs the location and frequency of recurrent translocations, including those driving B-cell malignancies.  相似文献   
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