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91.
Reintroduction of wood in rivers for restoration purposes is now recognized in a positive way by scientists. Nevertheless, the perception of wood in riverscapes is strongly affected by the socio-cultural environment. This cultural influence might explain why wood reintroduction is accepted and promoted in some regions of the world but not in others, despite the demonstrated ecological benefits. From an extensive student perception survey, we show that most of the groups from nine countries in the world considered riverscapes with wood to be less aesthetic, more dangerous, and needing more improvement than riverscapes without wood. By contrast, this way of thinking was not observed in Germany, Sweden, and Oregon (USA), where the first instances of wood reintroduction occurred.  相似文献   
92.
The locomotor activity rhythm of flies from four populations of Drosophila melanogaster, maintained under constant light for more than 600 generations, was recorded in continuous light (LL) and continuous darkness (DD) using four different protocols. The main objective behind these experiments was to estimate the proportion of flies exhibiting circadian rhythm of locomotor activity in LL, and to investigate whether this could be increased by subjecting the flies to various light regimes. About 26% of the flies exhibited a circadian rhythm of locomotor activity in LL, and the proportion increased to about 48% after an exposure to 12 h of darkness. About 77% of the flies exhibited a circadian locomotor activity rhythm in DD. Persistence of circadian locomotor activity rhythm in a considerable proportion of these flies suggests an intrinsic adaptive value to possessing circadian rhythmicity, derived, perhaps, from the need to synchronise various processes within the organism.  相似文献   
93.
资源利用与资源退化在时间及空间领域上的表现有所分异。识别出那些受人为干扰严重且易于发生资源退化的区域(资源利用的热点地区),对这些区域给予重视并采取特殊的管理机制以避免资源的进一步退化和环境的恶化,对资源的可持续利用具有重要的现实意义。论文以印度北部山地小流域的研究为例,根据当地实际情况,选取4个参数作为评价指标,即资源利用的重要性、资源的需求程度、资源利用的可获取性以及人类活动造成的景观生态学的干扰指数,利用遥感技术和地理信息系统对资源利用热点地区的识别进行了初步探讨。通过研究,将该流域划分为3种区域,即高度敏感区、中度敏感区和低敏感区,分别体现了不同的资源退化在空间上的分布。  相似文献   
94.
Mutations for activity level, designated hpa and hra, in Drosophila jambulina altered properties of the pacemaker controlling eclosion rhythm. Entrainment of eclosion rhythm was studied in light-dark (LD) cycles of 12:12 h at 28°C. The wild type strain entrained to LD cycles but the hpa or hra strain did not. When these strains were released from constant light (LL) to constant darkness (DD), the wild type strain free-ran while other two strains were arrhythmic. Temperature cycles entrained the wild type and hpa strain in DD and LL, and when transferred to constant temperature following thermoperiodic entrainment, the wild type strain free-ran in DD, while the hpa strain free-ran in LL as if the input of LL was essential for its free-running state. Temperature cycles entrained the hra strain in DD but not in LL, and free-running rhythmicities were never established, suggesting that the hra mutation has altered the basic properties of its pacemaker.  相似文献   
95.
Performance evaluation of two reverse osmosis (RO) desalination plants (DSP) at villages: Melasirupodhu (30 m3 day-1) and Sikkal (50 m3 day-1) in Ramanathpuram district,Tamil Nadu (India) were studied so as to bring out the state-of-art of their operation and maintenance (O&M). Detailedinformation on plant design and engineering, water quality,plant personnel, and cost of O&M was collected for a period ofthree years after commissioning of the two plants. Feed waterwas brackish, the TDS varied in the range of 6500–8500 mg L-1 at Melasirupodhu and 5300–7100 mg L-1 atSikkal villages. The product water quality was observed to begradually deteriorating as the salt rejection by the membranesdecreased with time. The salt rejection was 97–99% atthe time of commissioning of the plants, and came down to89–90% at the end of 3 years of operation. Product water TDS soonafter installation of the plants was excellent and within desirable limits of BIS. After three years of operation, few parameters exceeded the desirable limits, however, they were found to be within permissible limits of BIS. The analyses of thedata showed that both plants were operated only at 30–36% of the design capacity. Plant shut-down due to inadequate and erratic power supply, and plant break-down and inherent delay in repairs due to lack of adequate infrastructure were found tobe the major causes for the low utilization of the plants. Consequently the recurring cost of product water production enhanced to Rs. 25.0/m3 at Melasirupodhu and Rs. 17.5 m-3 at Sikkal, as against the estimated cost of Rs. 15.0/m3 and Rs. 11.0/m3, respectively, as per the design. Over the years, the energy consumption for the product water output increased reflecting higher operational pressures needed with the aging of the membranes.  相似文献   
96.
The indiscriminate and injudicious use of pesticides particularly endosulfan in agriculture and animal husbandry practices has considerably increased the risk of human health hazard. The present work was therefore undertaken to evaluate the toxic effect of endosulfan on the vital organs viz. liver and kidney of rat. Oral administration of endosulfan at the dose level of 10 mg/kg b.wt./day for two and four weeks showed toxic interference with the biochemistry and histology of rat liver and kidney. The biochemical parameters viz. Aspartate amino transferase, alanine amino transferase, acid phosphatase, alkaline phosphatase, bilirubin urea and creatinine were increased which clearly showed the hepato and nephrotoxic effect of endosulfan. Histopathologically the size of liver was increased, sinusoidal dilation, pyknotic nuclei, cytoplasmic degranulation and various nuclear aberrations were observed. Similarly pathological alterations viz. chronic glomerulonephritis, glomerulosclerosis, odenoma and glomerulus deposits were observed in the kidney.  相似文献   
97.
The ecotoxicities of three organic compounds containing spacer groups, an intermediate organotin premonomer, four organotin monomers, their homopolymers and six copolymers of tributylin α‐chloroacrylate (TCA) are reported against two microorganisms viz., Pseudomonas aeruginosa and Sarcina lutea and a larval species Anemia salina (Nauplii II). The organic compounds containing spacer group were less toxic whereas the monomers were found to be highly toxic. The homopolymers were found to be more toxic than that of tributyltin acrylate (TBTAA), tributyltin methacrylate (TBTMA) and tributyltin α‐Chloroacrylate (TCA). The toxicity of TCA copolymers increased with the increase in tributyltin (TBT) content in the polymer. From this study it was not possible to establish any relationship between the chemical nature of the comonomer with its toxicity.  相似文献   
98.
Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA's Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson's ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases even below the reporting limit. The leachable Chromium was reduced from 0.153 down to 0.0045 mg/L, Arsenic from 0.256 down to 0.132 mg/L, Selenium from 1.05 down to 0.29 mg/L, Silver from 0.011 down to .001 mg/L, Barium from 2.06 down to 0.314 mg/L and Mercury from 0.007 down to 0.001 mg/L. Although the leachable Cd exhibited an increase from 0.49 up to 0.805 mg/L and Pd from 0.002 up to 0.029 mg/L, these were well below the maximum limits of 1.00 and 5.00 mg/L, respectively.  相似文献   
99.

We examine the dynamics and spatial determinants of land change in India by integrating decadal land cover maps (1985–1995–2005) from a wall-to-wall analysis of Landsat images with spatiotemporal socioeconomic database for ~630,000 villages in India. We reinforce our results through collective evidence from synthesis of 102 case studies that incorporate field knowledge of the causes of land change in India. We focus on cropland–fallow land conversions, and forest area changes (excludes non-forest tree categories including commercial plantations). We show that cropland to fallow conversions are prominently associated with lack of irrigation and capital, male agricultural labor shortage, and fragmentation of land holdings. We find gross forest loss is substantial and increased from ~23,810 km2 (1985–1995) to ~25,770 km2 (1995–2005). The gross forest gain also increased from ~6000 km2 (1985–1995) to ~7440 km2 (1995–2005). Overall, India experienced a net decline in forest by ~18,000 km2 (gross loss–gross gain) consistently during both decades. We show that the major source of forest loss was cropland expansion in areas of low cropland productivity (due to soil degradation and lack of irrigation), followed by industrial development and mining/quarrying activities, and excessive economic dependence of villages on forest resources.

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100.
In the present study, noise levels were measured in two different areas within Haridwar City viz., residential and commercial area, on festive day and non-festive day (after) of Deepawali in November 2007. The results show that there is an enhanced pressure of noise during the festival of light. The average noise level on festive day shows a rise of 29.6 and 18.1% when compared to non-festive day, respectively, for residential and commercial area.  相似文献   
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