首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
PM2.5 refers to particulate matter (PM) in air that is less than 2.5μm in aerodynamic diameter, which has negative effects on air quality and human health. PM2.5 is the main pollutant source in haze occurring in Beijing, and it also has caused many problems in other cities. Previous studies have focused mostly on the relationship between land use and air quality, but less research has specifically explored the effects of urban landscape patterns on PM2.5. This study considered the rapidly growing and heavily polluted Beijing, China. To better understand the impact of urban landscape pattern on PM2.5 pollution, five landscape metrics including PLAND, PD, ED, SHEI, and CONTAG were applied in the study. Further, other data, such as street networks, population density, and elevation considered as factors influencing PM2.5, were obtained through RS and GIS. By means of correlation analysis and stepwise multiple regression, the effects of landscape pattern on PM2.5 concentration was explored. The results showed that (1) at class-level, vegetation and water were significant landscape components in reducing PM2.5 concentration, while cropland played a special role in PM2.5 concentration; (2) landscape configuration (ED and PD) features at class-level had obvious effects on particulate matter; and (3) at the landscape-level, the evenness (SHEI) and fragmentation (CONTAG) of the whole landscape related closely with PM2.5 concentration. Results of this study could expand our understanding of the role of urban landscape pattern on PM2.5 and provide useful information for urban planning.  相似文献   

2.
The research study investigated the possible associations among science and biology teachers?? knowledge and belief variables concerning teaching evolution in science and biology classes. Specifically, this study examined how a set of variables including teachers?? understanding of evolution and nature of science (NOS) is related to the set of variables including teachers?? acceptance of evolution and perceptions of teaching evolution (i.e., perceptions of the necessity of addressing evolution in their classrooms, perceptions of the factors that impede addressing evolution in their classrooms, and personal science teaching efficacy beliefs regarding evolution). Data were collected from science and biology teachers through administration of Evolution Content Knowledge Test, Measure of Acceptance of the Theory of Evolution, Nature of Science as Argument Questionnaire and Teachers?? Perceptions of Teaching Evolution Scale. Canonical correlation analysis findings suggested that teachers who had thorough understanding of evolution and NOS were likely to both accept the scientific validity of evolution and believe the necessity of addressing evolution in the classrooms. On the other hand, teachers with thorough understanding of evolution and NOS did not necessarily believe that they have a stronger sense of self-efficacy beliefs regarding teaching evolution and that there are fewer obstacles to addressing evolution in the classroom. The research is significant in that it provides empirical evidence clarifying the interactions between teachers?? understanding and beliefs in teaching evolution. Implications for science teacher education are discussed.  相似文献   

3.
Human Ecology - Previous studies have reported that older people are more knowledgeable about nature than the younger generation. The relationship between people’s age and level of knowledge...  相似文献   

4.

Background

International migration poses important challenges to European health care systems. The development of “migrant friendly hospitals” has been identified as a priority in both Europe and Switzerland.

Methods

A multi-pronged initiative was developed at Geneva University Hospitals (HUG) to improve staff knowledge and use of existing “migrant friendly” resources. A self-administered questionnaire was sent pre and post-intervention to random samples of 4 major professional groups with direct patient contact at the HUG. The questionnaire assessed staff knowledge, attitudes and reported practices regarding the care of migrant patients.

Results

Overall response rate was 51% (N = 1460) in 2010 but only 19% (N = 761) in 2013 owing to an institutionally imposed change in survey method. Despite these difficulties, and after adjusting for sample differences, we found that respondents in 2013 were significantly more likely to have received training in how to organize an appointment with an interpreter, how to work with an interpreter and about health and social services available for migrant patients. Respondents were also significantly more likely to have used several Migrant Friendly structures at the HUG. Use of, preference for and perceived skill at working with professional interpreters all improved, and respondents were both more likely to be encouraged by their supervisors to use professional interpreters, and less likely to be encouraged to look for alternative solutions for communicating with non francophone patients. Finally, 2013 respondents encountered fewer difficulties caring for migrant patients, although lack of time and language barriers continued to be the most important sources of difficulty.

Conclusion

Our results suggest that an institution-wide information campaign may contribute to increased awareness and use of migrant friendly resources by clinical staff. Hospital commitment and financing, along with inter-departmental participation in all activities were important in creating and maintaining project visibility, and in contributing to a migrant friendly institutional culture.  相似文献   

5.
Recently published biochemical data suggest the significant role of selenium compounds as the adjuvants combined with L: -thyroxine therapy, which can reduce antithyroid peroxidase antibodies' (TPOAb) levels in patients with Hashimoto disease. The study was undertaken to document in a more detailed way the changes in parameters expressing the thyroid and ovarian function brought about by selenium supplementation (50-100 microg/day) in a woman undergoing autoimmune thyroiditis (AIT) therapy. This prospective observational case study lasted for 14 months plus additional 5 months as a follow-up period. Parameters reflecting selenium status, thyroid metabolism, and sex hormones secretion were determined at the onset and end of the study period, as well as in some of its middle points. During the supplementation trial, serum selenium (Se) increased by 45% and plasma glutathione peroxidase (GPX3) by 21%. TPOAb decreased by 76%. All other parameters also fluctuated during the supplementation period, but all results were always within normal physiological ranges. After withdrawal of the supplementation, the sharp fall of Se and GPX3 promptly occurred, and this phenomenon was accompanied with a marked increase in TPOAb. This report stresses the importance of selenium supplementation in AIT treatment. However, the efficiency and durability of the effect of Se supplementation on the TPOAb titer remain an open question. The clarification of mechanism(s) underlying Se interaction with autoimmune processes should throw new light on this issue.  相似文献   

6.
We compared the performances of the candidate loci for moss DNA barcoding and the primers used in amplifying the loci. Primers for three coded loci (matK, rps4 and rbcL a) and four non coded loci (atpB rbcL, atpF H, psbK I and trnH psbA) of the chloroplast genome, one from the mitochondrial genome (nad5), and one from the nucleus genome (ITS2) were evaluated. Seventy four samples representing 14 species belonging to five genera of Trachypodoaceae (or Meteoriaceae) were screened. All primers for matK and a pair of primers for trnH psbA failed. Low successes were encountered with the primers for atpF H and psbK I. The primers for psbK I produced several bands and the PCR products of atpF H were difficult to sequence. The powers of the remaining six loci were compared using the variability, identification success and the resolutions. It was found that ITS2 is the most promising candidate for DNA barcoding for mosses. Among the chloroplast genes, atpB rbcL exhibited the highest resolution. Although trnH psbA is very variable, it is too short to be an ideal barcode alone. Combinations of chloroplast genes were also tried and Ps of both atpB rbcL+trnH psbA and rbcL a++trnH psbA were 64% using NJ method. More additions of loci did not increase the resolution. No barcoding gap exists for all these loci. Phylogenetic analyses were carried out prior to the DNA barcoding evaluation and some taxonomic problems do exist. This study exemplifies the necessity of correct species delimitation and the adoption of both plastid and nuclear loci in plant DNA barcoding.  相似文献   

7.
To effectively conserve sour orange (Citrus aurantium L.) germplasm on two islands at the estuary of the Yangtze River in China, we estimated genetic variation and relationships of the known parental trees and their proposed descendents (young trees) using the fingerprints of random amplified polymorphic DNA (RAPD). Results based on RAPD analyses showed considerable genetic diversity in the parental populations (He = 0.202). The overall populations including the parental and young trees showed slightly higher genetic diversity (He = 0.298) than the parents, with about 10% variation between populations. An unweighted pair group method with arithmetic mean analysis dendrogram based on cluster analysis of the Jaccard similarity among individuals demonstrated a more complicated relationship of the parental and young trees from the two islands, although the young trees showed a clear association with parental trees. This indicates a significant contribution of parental trees in establishing the sour orange populations on the two islands. According to farmers' knowledge, conservation of only one or two parental trees would be sufficient because they believed that the whole populations were generated from a single mother tree. However, this study suggests that preserving most parental trees and some selected young trees with distant genetic relationships should be an effective conservation strategy for sour orange germplasm on the two islands.  相似文献   

8.
Despite widespread use of species-area relationships (SARs), dispute remains over the most representative SAR model. Using data of small-scale SARs of Estonian dry grassland communities, we address three questions: (1) Which model describes these SARs best when known artifacts are excluded? (2) How do deviating sampling procedures (marginal instead of central position of the smaller plots in relation to the largest plot; single values instead of average values; randomly located subplots instead of nested subplots) influence the properties of the SARs? (3) Are those effects likely to bias the selection of the best model? Our general dataset consisted of 16 series of nested-plots (1 cm2–100 m2, any-part system), each of which comprised five series of subplots located in the four corners and the centre of the 100-m2 plot. Data for the three pairs of compared sampling designs were generated from this dataset by subsampling. Five function types (power, quadratic power, logarithmic, Michaelis-Menten, Lomolino) were fitted with non-linear regression. In some of the communities, we found extremely high species densities (including bryophytes and lichens), namely up to eight species in 1 cm2 and up to 140 species in 100 m2, which appear to be the highest documented values on these scales. For SARs constructed from nested-plot average-value data, the regular power function generally was the best model, closely followed by the quadratic power function, while the logarithmic and Michaelis-Menten functions performed poorly throughout. However, the relative fit of the latter two models increased significantly relative to the respective best model when the single-value or random-sampling method was applied, however, the power function normally remained far superior. These results confirm the hypothesis that both single-value and random-sampling approaches cause artifacts by increasing stochasticity in the data, which can lead to the selection of inappropriate models.  相似文献   

9.
10.

Background

Research on the temporal relationship of parental risk factors with offspring’s suicide attempt is scarce and a life course approach has not been applied to date. We investigated the temporal relationship of parental morbidity and mortality with offspring’s suicide attempt and whether any such association was modified by offspring’s age at attempt.

Methods

We designed a case-control study through linkage of Swedish registers. Cases comprised all individuals in Sweden born 1973–1983 with inpatient care due to suicide attempt (15–31 years of age) and with information on both biological parents (N = 15 193). Ten controls were matched to each case (National Patient register with national complete coverage). Conditional logistic and spline regressions were applied.

Results

Particularly for women, most parental markers showed the strongest effect sizes if exposure was short-term (within 2 years after exposure) and related to the mother. Especially short-term exposure to maternal inpatient care due to psychiatric diagnoses had a significantly stronger effect on suicide attempt risk in women compared to men. Regarding exposure to parental inpatient care due to psychiatric diagnoses, short-term as opposed to long-term (exceeding 2 years after exposure) effects were highest during adolescence and decreased significantly with age for female and male offspring, respectively.

Conclusions

Although limited by the fact that data on parental morbidity and the outcome of suicidality were based on in-patient data only, the data suggest that the high risks of suicide attempt in case of exposure to parental psychopathology and suicidal behavior particularly during adolescence and the strong short-term effects associated with maternal psychopathology for female offspring are of direct clinical importance.  相似文献   

11.
RNA-Seq is a powerful tool for the annotation of genomes, in particular for the identification of isoforms and UTRs. Nevertheless, several software tools exist and no standard strategy to obtain a reliable annotation is yet established. We tested different combinations of the most commonly used reference-based alignment tools (TopHat, GSNAP) in combination with two frequently used reference-based assemblers (Cufflinks, Scripture) and evaluated the potential of RNA-Seq to improve the annotation of Drosophila pseudoobscura. While GSNAP maps a higher proportion of reads, TopHat resulted in a more accurate annotation when used in combination with Cufflinks. Scripture had the lowest sensitivity. Interestingly, after subsampling to the same coverage for GSNAP and TopHat, we find that both mappers have similar performance, implying that the advantage of TopHat is mainly an artifact of the lower coverage. Overall, we observed a low concordance among the different approaches tested both at junction and isoform levels. Using data from both sexes of two adult strains of D. pseudoobscura we detected alternative splicing for about 30% of the FlyBase multiple-exon genes. Moreover, we extended the boundaries for 6523 genes (about 40%). We annotated 669 new genes, 45% of them with splicing evidence. Most of the new genes are located on unassembled contigs, reflecting their incomplete annotation. Finally, we identified 99 additional new genes that are not represented in the current genome contigs of D. pseudoobscura, probably due to location in genomic regions that are difficult to assemble (e.g. heterochromatic regions).  相似文献   

12.
Uses and Conservation of Plant Species in a National Park—A Case Study of Ben En, Vietnam. This paper surveys the use of wild and cultivated plants by local people in Ben En National Park, Vietnam, and analyzes its impact on the conservation status of some of the utilized species. A total of 208 species used for a range of nonmedicinal purposes are listed. See Hoang et al. (2008a) for 230 medicinal plants used in the park. Most species are used for food. The use of plants contributes very significantly to the livelihood of local people in the park, but the current use patterns are not sustainable and would lead to local extinction of rare and endangered species if no additional conservation measures are introduced. Men collect nonmedicinal plants more often than women. A total of 38 useful plant species are commercialized, and contribute 12% of the average income of individual households. Bamboo shoots of Schizostachyum funghomii (Poaceae) are the most important for income generation. The monetary equivalent of noncommercialized useful plants probably far exceeds the value of the traded plant products. Plant use is independent of the ethnicity of the different populations living in the park. Larger households make use of a greater variety of useful plant species than small families. Abundant species in the forest have a higher use index (UI) than less common species. Out of the 208 useful species, as many as 27 were found to be endangered locally, many more than the 11 or 8 endangered species included in national or global red lists. Currently, useful plants, especially important timber trees, are more abundant in the less disturbed parts of the park, far away from the villages, indicating the pressures of illegal logging and harvesting near villages on the ecosystems.  相似文献   

13.
In aquatic ecosystems, predation is affected both by turbulence and visibility, but the combined effects are poorly known. Both factors are changing in lakes in the Northern Hemisphere; the average levels of turbulence are predicted to increase due to increasing wind activities, while water transparency is decreasing, e.g., due to variations in precipitation, and sediment resuspension. We explored experimentally how turbulence influenced the effects of planktivorous fish and invertebrate predators on zooplankton when it was combined with low visibility caused by high levels of water color. The study was conducted as a factorial design in 24 outdoor ponds, using the natural zooplankton community as a prey population. Perch and roach were used as vertebrate predators and Chaoborus flavicans larvae as invertebrate predators. In addition to calm conditions, the turbulent dissipation rate used in the experiments was 10−6 m2 s−3, and the water color was 140 mg Pt L−1. The results demonstrated that in a system dominated by invertebrates, predation pressure on cladocerans increased considerably under intermediate turbulence. Under calm conditions, chaoborids caused only a minor reduction in the crustacean biomass. The effect of fish predation on cladocerans was slightly reduced by turbulence, while predation on cyclopoids was strongly enhanced. Surprisingly, under turbulent conditions fish reduced cyclopoid biomass, whereas in calm water it increased in the presence of fish. We thus concluded that turbulence affects fish selectivity. The results suggested that in dystrophic invertebrate-dominated lakes, turbulence may severely affect the abundance of cladocerans. In fish-dominated dystrophic lakes, on the other hand, turbulence-induced changes in planktivory may considerably affect copepods instead of cladocerans. In lakes inhabited by both invertebrates and fish, the response of top-down regulation to turbulence resembles that in fish-dominated systems, due to intraguild predation. The changes in planktivorous predation induced by abiotic factors may possibly cascade to primary producers.  相似文献   

14.
Agriculture is one of the most vulnerable sectors to climate change. Farmers have been exposed to multiple stressors including climate change, and they have managed to adapt to those risks. The adaptation actions undertaken by farmers and their decision making are, however, only poorly understood. By studying adaptation practices undertaken by apple farmers in three regions: Nagano and Kazuno in Japan and Elgin in South Africa, we categorize the adaptation actions into two types: farmer initiated bottom-up adaptation and institution led top-down adaptation. We found that the driver which differentiates the type of adaptation likely adopted was strongly related to the farmers’ characteristics, particularly their dependence on the institutions, e.g. the farmers’ cooperative, in selling their products. The farmers who rely on the farmers’ cooperative for their sales are likely to adopt the institution-led adaptation, whereas the farmers who have established their own sales channels tend to start innovative actions by bottom-up. We further argue that even though the two types have contrasting features, the combinations of the both types of adaptations could lead to more successful adaptation particularly in agriculture. This study also emphasizes that more farm-level studies for various crops and regions are warranted to provide substantial feedbacks to adaptation policy.  相似文献   

15.
Evolutionary adaptation affects demographic resilience to climate change but few studies have attempted to project changes in selective pressures or quantify impacts of trait responses on population dynamics and extinction risk. We used a novel individual-based model to explore potential evolutionary changes in migration timing and the consequences for population persistence in sockeye salmon Oncorhynchus nerka in the Fraser River, Canada, under scenarios of future climate warming. Adult sockeye salmon are highly sensitive to increases in water temperature during their arduous upriver migration, raising concerns about the fate of these ecologically, culturally, and commercially important fish in a warmer future. Our results suggest that evolution of upriver migration timing could allow these salmon to avoid increasingly frequent stressful temperatures, with the odds of population persistence increasing in proportion to the trait heritability and phenotypic variance. With a simulated 2°C increase in average summer river temperatures by 2100, adult migration timing from the ocean to the river advanced by ~10 days when the heritability was 0.5, while the risk of quasi-extinction was only 17% of that faced by populations with zero evolutionary potential (i.e., heritability fixed at zero). The rates of evolution required to maintain persistence under simulated scenarios of moderate to rapid warming are plausible based on estimated heritabilities and rates of microevolution of timing traits in salmon and related species, although further empirical work is required to assess potential genetic and ecophysiological constraints on phenological adaptation. These results highlight the benefits to salmon management of maintaining evolutionary potential within populations, in addition to conserving key habitats and minimizing additional stressors where possible, as a means to build resilience to ongoing climate change. More generally, they demonstrate the importance and feasibility of considering evolutionary processes, in addition to ecology and demography, when projecting population responses to environmental change.  相似文献   

16.
Though the HIV/AIDS epidemic in Southeastern Europe is one of low reported prevalence, numerous studies have described the pervasiveness of medical providers’ lack of knowledge of HIV/AIDS in the Balkans. This study sought to culturally adapt an instrument to assess medical providers’ knowledge of and attitudes towards HIV/AIDS in Albania. Cultural adaptation was completed through development of a survey from previously validated instruments, translation of the survey into Albanian, blinded back translation, expert committee review of the draft instrument, focus group pre-testing with community- and University Hospital Center of Tirana-based physicians and nurses, and test-retest reliability testing. Blinded back translation of the instrument supported the initial translation with slight changes to the idiomatic and conceptual equivalences. Focus group pre-testing generally supported the instrument, yet some experiential and idiomatic changes were implemented. Based on unweighted kappa and/or prevalence adjusted bias adjusted kappa (PABAK), 20 of the 43 questions were deemed statistically significant at kappa and/or PABAK ≥0.5, while 12 others did not cross zero on the 95% confidence interval for kappa, indicating their probable significance. Subsequently, an instrument to assess medical providers’ knowledge of and attitudes toward HIV/AIDS for an Albanian population was developed which can be expanded within Albania and potentially to other countries within the Balkans, which have an Albanian-speaking population.  相似文献   

17.
18.
19.
As an index to the rate of fat utilization in human subjects, the recovery of all radioactive carbon dioxide in the expired air was measured for one hour following intravenous injection of palmitate-1-C14. In the normal fasted subject, about 10 per cent of the injected dose was recovered, and the proportion was lowered to about 5 per cent by administration of glucose. With prolonged fasting, the recovery of radioactive carbon dioxide did not change, despite a rising concentration of fatty acids in the serum. This was interpreted as due to the development of a balance between increasing mobilization and oxidation and was thought to indicate increasing fatty acid oxidation.In chronic undernutrition and diabetes mellitus there was increased fatty acid oxidation due presumably to adaptation to a chronic increase in fat utilization for energy.Administration of human growth hormone did not increase fat oxidation but prevented the usual inhibition produced by glucose. This was interpreted to mean that growth hormone increases fat utilization only indirectly by inhibiting the usual preferential utilization of glucose over fat.  相似文献   

20.
Wang P  Shen H  Xie P 《Microbial ecology》2012,63(2):369-382
Diatom blooms occur in many water bodies worldwide, causing significant ecological and social concerns. In order to understand the mechanisms of diatom blooms formation, the effects of varying phosphorus (P) concentration and hydrodynamics on the growth of diatoms were studied by combining results from field observations and laboratory experiments. The field investigation showed that spring diatom blooms (Cyclotella meneghiniana and Stephanodiscus hantzschii) occurred in Lake Taihu and Hanjiang River with similar environmental factors such as water temperature, pH, and dissolved oxygen in 2008. Concentrations of total phosphorus (TP), total nitrogen, and ammonia nitrogen (NH4-N) in Lake Taihu were significantly higher than the concentrations in the Hanjiang River. Laboratory experiments were conducted to evaluate growth and physiological responses of four lotic diatoms (Cyclotella atomus, Fragilaria crotonensis, Nitzschia palea, and S. hantzschii, isolated from the Hanjiang River) and three lentic diatoms (C. meneghiniana, Melosira varians, and Stephanodiscus minutulus, isolated from Lake Taihu, Lake Donghu, and Guanqiao Pond, respectively) to various P concentrations under small-scale turbulent and standing conditions. Our results showed that, with turbulence, lotic diatoms C. atomus, F. crotonensis, N. palea, and S. hantzschii demonstrated a significant increase in affinity for P compared with lentic diatoms C. meneghiniana, M. varians, and S. minutulus. Moreover, lotic diatoms C. atomus, F. crotonensis, and N. palea had higher growth rates and photosynthetic efficiencies with small-scale turbulence than with standing conditions both in P-limited and P-replete conditions. Lotic species S. hantzschii and three lentic diatoms (C. meneghiniana, M. varians, and S. minutulus) grew well under standing conditions. Our results may explain our field observation that the occurrence of diatom blooms in lakes is often associated with higher TP concentrations whereas in rivers, diatom blooms occur at a wide range of TP concentrations under flows. Therefore, different hydrodynamics and nutrient concentrations determined the dominant diatom species, according to their habitat-dependent physiological characteristics.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号