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101.
In recent years, many city authorities in Europe and North America have sought to attract people back to city centres for leisure, shopping, business and residence. The planning measures commonly adopted take explicit account of issues of crime and safety. The concept of `community safety' as applied to the city centre is problematic, however, as users have diverse lifestyles, interests and values which impact on their own and others' safety. This paper reports on a study of the experiences and perceptions of safety of different groups of city centre users in Newcastle upon Tyne, England. While social identities and roles shaped the extent of concern and subsequent impacts on people's use of the city centre space, the research suggested that many concerns are genuinely shared. The paper investigates the congruence of a range of planning strategies with city centre users' safety concerns. Situational measures were viewed with scepticism, as fear centres on the presence and behaviour of others. 相似文献
102.
目的 探讨高脂饮食大鼠肾脏3-羟基-3甲基戊二酰辅酶A合成酶2(HMGCS2)表达及可能调控机制。方法 断乳Wistar 雄性大鼠27只分为3组:正常对照组(CON)、高脂组(HFG)、绿茶多酚(green tea polyphenols,GTPs)组(G)。CON组大鼠喂养普通饲料,HFG组及GTPs组给予高脂饲料,GTPs组同时自由摄食绿茶多酚浓度为1.6g/L水溶液。26周后测定空腹血糖(FPG)、血清胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)、高密度脂蛋白(HDL)。免疫印迹法测定肾脏HMGCS2和Sirt3蛋白表达水平。结果 与CON组比较,HFG组大鼠体重和脂肪系数升高,血清FPG、TC、TG、LDL-C/HDLC均升高,差异有统计学意义(P<0.05);与HFG组比较,GTPs降低大鼠体重和脂肪系数,差异有统计学意义(P<0.05),GTPs组血清FPG、TC、TG、LDL-C/HDLC均不同程度降低,差异有统计学意义(P<0.05)。与CON组比较,肾脏组织HMGCS2的表达降低,差异有统计学意义(P<0.05);与HFG组比较,GTPs组增加肾脏HMGCS2的表达,差异有统计学意义(P<0.05)。高脂饮食、正常饮食和GTPs干预后,大鼠肾脏组织Sirt3蛋白表达差异无统计学意义。结论 高脂饮食可降低肾脏组织HMGCS2表达,绿茶多酚可逆转此效应;高脂饮食及绿茶多酚对肾脏组织HMGCS2表达的调控不经Sirt3途径。 相似文献
103.
2016年5月和8月浒苔暴发前后,分别对日照近岸海域浒苔暴发区进行了两个航次的浮游植物断面调查。两个航次中,硅藻都占据了调查海域浮游植物组成的主导地位,在种类数上和细胞丰度值上都占了较大的比例。8月航次细胞丰度明显高于5月航次,这与调查海域的历次调查结果相一致。应用PRIMER软件中的单变量分析得到群落种数(S)、丰富度(d)、香农-威纳指数(Shannon-Weaner index)(H′)和均匀度(J),从多样性指数分析可以看出,5月航次的生物多样性优于8月航次,5月航次调查海域浮游植物种类数量和空间分布都较均匀。两个航次中出现的优势种存在较大差别。 相似文献
104.
Japanese fisheries production in the Japan/East Sea between 1958 and 2003 increased to their peak (1.76 million tons) in the late 1980s and decreased abruptly with the collapse of Japanese sardine. Catch results for 58 fisheries and various environmental time-series data sets and community indices, including mean trophic level (MTL) and Simpson’s diversity index (DI), were used to investigate the impacts of fishing and climate changes on the structure of the fish community in the Tsushima warm current (TWC) region of the Japan/East Sea. The long-term trend in fisheries production was largely dependent on the Japanese sardine that, as a single species, contributed up to 60% of the total production in the Japanese waters of the Japan/East Sea during the late 1980s. Excluding Japanese sardine, production of the small pelagic species was higher during 1960s and 1990s but lower during 1970s and 1980s. This variation pattern generally corresponds with the trend in water temperature, warmer before early 1960s and after 1990s but colder during 1970s and 1980s. The warm-water, large predatory fishes and cold water demersal species show opposite responses to the water temperature in the TWC region, indicating the significant impact of oceanic conditions on fisheries production of the Japan/East Sea. Declines in demersal fishes and invertebrates during 1970s and 1980s suggested some impact of fishing. MTL and DI show a similar variation pattern: higher during 1960s and 1990s but lower during 1970s and 1980s. In particular, the sharp decline during the 1980s resulted from the abundant sardine catches, suggesting that dominant species have a large effect on the structure of the fish community in the Japan/East Sea. Principal component analysis for 58 time-series data sets of fisheries catches suggested that the fish community varied on inter-annual to inter-decadal scales; the abrupt changes that occurred in the mid-1970s and late 1980s seemed to correspond closely with the climatic regime shifts in the North Pacific. These results strongly suggest that the structure of the fish community in the Japan/East Sea was largely affected by climatic and oceanic regime shifts rather than by fishing. There is no evidence showing “fishing down food webs” in the Japan/East Sea. However, in addition to the impacts of abrupt shifts that occurred in the late 1980s, the large predatory and demersal fishes seem to be facing stronger fishing pressure with the collapse of the Japanese sardine. 相似文献
105.
106.
主要评估了美国国家大气研究中心的NCAR CESM(Community Earth System Model,NCAR)和中国科学院的CAS ESM(Earth System Model,Chinese Academy of Sciences)两个地球系统模式对亚洲东部夏季气候态的模拟性能。使用NCAR CESM和CAS ESM各两种不同的水平分辨率,一共进行了4组长达19年(1998~2016年)的数值积分试验,并通过对2 m气温、降水强度和降水日变化等的分析,比较了这两个模式在亚洲东部的模拟性能。结果表明,CAS ESM和NCAR CESM均能模拟出夏季2 m气温和降水强度的大尺度分布特征,但整体上模拟得到的地表面气温偏暖、降水强度偏弱。对于降水日变化而言,观测的日降水峰值在陆地上主要发生在下午到傍晚时段,在海洋上则出现在午夜到凌晨时段。两组低分辨率试验模拟的陆地降水峰值出现过早,且无法模拟出四川盆地的夜间降水峰值和部分海洋地区凌晨或上午的降水峰值。提高分辨率对模式的模拟性能有显著的提升作用。高分辨率下,NCAR CESM和CAS ESM对陆地和海洋的降水日变化模拟性能都明显提高。对降水日变化的定量化分析表明,高分辨率CAS ESM模式对整个亚洲东部降水日变化的模拟最优。目前模式对海陆风的模拟还不太理想,未来要进一步提高模式模拟性能,需要重点完善与气温、降水过程相关的物理参数化方案。 相似文献
107.
Hendrik Rujner Günther Leonhardt Jiri Marsalek Anna‐Maria Perttu Maria Viklander 《水文研究》2018,32(5):644-654
The effects of soil water content (SWC) on the formation of run‐off in grass swales draining into a storm sewer system were studied in two 30‐m test swales with trapezoidal cross sections. Swale 1 was built in a loamy fine‐sand soil, on a slope of 1.5%, and Swale 2 was built in a sandy loam soil, on a slope of 0.7%. In experimental runs, the swales were irrigated with 2 flow rates reproducing run‐off from block rainfalls with intensities approximately corresponding to 2‐month and 3‐year events. Run‐off experiments were conducted for initial SWC (SWCini) ranging from 0.18 to 0.43 m3/m3. For low SWCini, the run‐off volume was greatly reduced by up to 82%, but at high SWCini, the volume reduction was as low as 15%. The relative swale flow volume reductions decreased with increasing SWCini and, for the conditions studied, indicated a transition of the dominating swale functions from run‐off dissipation to conveyance. Run‐off flow peaks were reduced proportionally to the flow volume reductions, in the range from 4% to 55%. The swale outflow hydrograph lag times varied from 5 to 15 min, with the high values corresponding to low SWCini. Analysis of swale inflow/outflow hydrographs for high SWCini allowed estimations of the saturated hydraulic conductivities as 3.27 and 4.84 cm/hr in Swales 1 and 2, respectively. Such estimates differed from averages (N = 9) of double‐ring infiltrometer measurements (9.41 and 1.78 cm/hr). Irregularities in swale bottom slopes created bottom surface depression storage of 0.35 and 0.61 m3 for Swales 1 and 2, respectively, and functioned similarly as check berms contributing to run‐off attenuation. The experimental findings offer implications for drainage swale planning and design: (a) SWCini strongly affect swale functioning in run‐off dissipation and conveyance during the early phase of run‐off, which is particularly important for design storms and their antecedent moisture conditions, and (b) concerning the longevity of swale operation, Swale 1 remains fully functional even after almost 60 years of operation, as judged from its attractive appearance, good infiltration rates (3.27 cm/hr), and high flow capacity. 相似文献
108.
Experiments carried out with models of floating production, storage and offloading platforms (FPSOs) showed that the flow of water over the deck edge, onto the deck resembled a suddenly released wall of water rather than a breaking wave. Therefore green water flow onto the deck was simulated using dam breaking theory, but the theory’s shallow-water assumptions may be limiting. In this paper a non-linear dam breaking problem is formulated. Equations of motion in the Lagrangian form are used and the solution is sought as an infinite series in time. Comparisons with the shallow water approximation are carried out. 相似文献
109.
110.
The relationship between differences in microwave humidity sounder(MHS)–channel biases which represent measured brightness temperatures and model-simulated brightness temperatures, and cloud ice water path(IWP) as well as the influence of the cloud liquid water path(LWP) on the relationship is examined. Seven years(2011–17) of NOAA-18 MHS-derived measured brightness temperatures and IWP/LWP data generated by the NOAA Comprehensive Large Array-data Stewardship System Microwave Surface and Precipitation Products System are used. The Community Radiative Transfer Model, version2.2.4, is used to simulate model-simulated brightness temperatures using European Center for Medium-Range Weather Forecasts reanalysis data as background fields. Scan-angle deviations of the MHS window channel biases range from-1.7 K to1.0 K. The relationships between channels 2, 4, and 5 biases and scan angle are symmetrical about the nadir. The latitudedependent deviations of MHS window channel biases are positive and range from 0–7 K. For MHS non-window channels,the latitudinal deviations between measured brightness temperatures and model-simulated brightness temperatures are larger when the detection height is higher. No systematic warm or cold deviations are found in the global spatial distribution of difference between measured brightness temperatures and model-simulated brightness temperatures over oceans after removing scan-angle and latitudinal deviations. The corrected biases of five different MHS channels decrease differently with respect to the increase in IWP. This decrease is stronger when LWP values are higher. 相似文献