矿区土地复垦与再利用

矿区的环境破坏 采矿活动促进了人类社会、经济和文明的发展,但大部分矿产的开发与利用不可避免地占用且破坏了大量的地表土地,并严重破坏原有的环境,引起一系列的环境问题.例如,平原变成高低不平的坑洞,肥沃的农田变成沼泽地;尘土飞扬,废水、废气渗溢;矿区地下水位下降、含水层枯竭、水体消失,井泉干涸;山崩地滑、土地荒漠化加剧等.     

Population-level analysis on reduction in equilibrium population size of the azuki bean beetle

Summary Responses of laboratory population of the azuki bean beetleCallosobruchus chinensis to temperature conditions of 30°C and 32°C are compared. Equilibrium population size was found to be lower at 32°C. A one-generation process examined by reproduction-curve experiments is divided into two consecutive life stages specified by different habitats, i.e., outside and inside beans. Modified logistic difference equations are used to describe these population-level responses at each life stages. Sensitivity analysis is used to determine parameters of importance, thus determining the main cause of the reduced equilibrium population size at 32°C. The reduction resulted from the decrease in maximum population size of emerged adults which have experienced inside-bean process. The application and limitation of this population-level analysis to different levels are discussed.     

Niche modification and stability of competitive systems. III. Simulation model analysis

Summary Simulation model for niche shift in ecological time scale was constructed on the basis of the optimal foraging theory. In accordance with the previous experimental study (Shimada andFujii, 1985), the model competitive system consisted of 2 parasitoid wasp species utilizing 4 host stages. Wasps were assumed to choose host stages in the manner that they realized the maximal gain/cost values, where gain was represented by body weight of a wasp progeny emerging from each host stage and cost was expressed by time required to search for and detect an unparasitized host. The number of parasitized hosts in each host stage was calculated numerically by usingArditt's (1983) model for avoidance of superparasitism. The model simulated well the experimental results ofShimada andFujii (1985) andShimada (1985). Sensitivity analysis of the model showed that the experimentally derived criterion for competitive coexistence (different second-best host stages between competing species even with the common best) was not necessarily the indispensable condition for niche shift and separation, but that if the criterion was not satisfied, stable competitive coexistence occurred only in the narrow range of the parametric values. Further, niche shift in ecological time scale made the competitive coexistence more stable than fixed niche on which the current niche theory stands.     

Risk Assessment of the Carbon Nanotube Group

This study assessed the health risks via inhalation and derived the occupational exposure limit (OEL) for the carbon nanotube (CNT) group rather than individual CNT material. We devised two methods: the integration of the intratracheal instillation (IT) data with the inhalation (IH) data, and the “biaxial approach.” A four‐week IH test and IT test were performed in rats exposed to representative materials to obtain the no observed adverse effect level, based on which the OEL was derived. We used the biaxial approach to conduct a relative toxicity assessment of six types of CNTs. An OEL of 0.03 mg/m³ was selected as the criterion for the CNT group. We proposed that the OEL be limited to 15 years. We adopted adaptive management, in which the values are reviewed whenever new data are obtained. The toxicity level was found to be correlated with the Brunauer‐Emmett‐Teller (BET)‐specific surface area (BET‐SSA) of CNT, suggesting the BET‐SSA to have potential for use in toxicity estimation. We used the published exposure data and measurement results of dustiness tests to compute the risk in relation to particle size at the workplace and showed that controlling micron‐sized respirable particles was of utmost importance. Our genotoxicity studies indicated that CNT did not directly interact with genetic materials. They supported the concept that, even if CNT is genotoxic, it is secondary genotoxicity mediated via a pathway of genotoxic damage resulting from oxidative DNA attack by free radicals generated during CNT‐elicited inflammation. Secondary genotoxicity appears to involve a threshold.     

Measure of departure from symmetry for the analysis of collapsed square contingency tables with ordered categories

For square contingency tables with ordered categories, there may be some cases that one wants to analyze them by considering collapsed tables with some adjacent categories combined in the original table. This paper considers the symmetry model for collapsed square contingency tables and proposes a measure to represent the degree of departure from symmetry. The proposed measure is defined as the arithmetic mean of submeasures each of which represents the degree of departure from symmetry for each collapsed 3×3 table. Each submeasure also represents the mean of power-divergence or diversity index for each collapsed table. Examples are given.     

Sleep quality and stress in women with pregnancy-induced hypertension and gestational diabetes mellitus

BackgroundPregnant women with complications including pregnancy-induced hypertension (PIH) and gestational diabetes mellitus (GDM) often experience disrupted sleep patterns because of activation of the sympathetic nervous system. These pathologies are aggravated by sympathetic nervous system activation and may be related to stress. The present study aimed to clarify the characteristics of and changes in sleep quality and stress in pregnant women with PIH and GDM during the second and third trimesters.MethodsWe enrolled 56 women in their second or third trimesters who were diagnosed with PIH or GDM. Participants completed questionnaires, including the Pittsburgh Sleep Quality Index (PSQI) and the Perceived Stress Scale (PSS). Secretory immunoglobulin A (SlgA) concentrations were measured as a biological indicator of stress.ResultsPSS scores and subjective stress parameters were significantly higher than those reported from previous studies of healthy pregnant women (15.2 points and 15.1 points for the second and third trimesters, respectively).Mean one-day values for SIgA were 168.3 and 205.7 μg/mL for the second and third trimesters, respectively. During the second and third trimesters, SIgA scores were higher than those reported for healthy pregnant women in previous studies. The PSQI component scores sleep disturbance (C5) and sleep duration (C3) in follow up case were significantly higher in the third trimester than in the second trimester.DiscussionThis investigation suggests that pregnant women with PIH and GDM experience higher stress levels than do non-pregnant women and healthy pregnant women. Further, our results indicate that sleep quality worsens during the third trimester compared with the second trimester.     

Parasitoids as model organisms for ecologists

This paper introduces the special issue of this journal, which is devoted to parasitoid ecology. We provide a brief review of the role that parasitoids have played in research in population, community, and behavioral ecology and speculate on their future importance to the subject. Received: January 11, 1999 / Accepted: January 19, 1999     

The impact of jumps and leverage in forecasting covolatility

ABSTRACT

The paper investigates the impact of jumps in forecasting covolatility, accommodating leverage effects. We modify the preaveraged truncated covariance estimator of Koike (2016 Koike, Y. (2016). Estimation of integrated covariances in the simultaneous presence of non-synchronicity, microstructure noise and jumps. Econometric Theory 32:533–611.[Crossref], [Web of Science ®] , [Google Scholar]) such that the estimated matrix is positive definite. Using this approach, we can disentangle the estimates of the integrated covolatility matrix and jump variations from the quadratic covariation matrix. Empirical results for three stocks traded on the New York Stock Exchange indicate that the cojumps of two assets have a significant impact on future covolatility, but the impact is negligible for forecasting weekly and monthly horizons.