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 250 毫秒
1.
Enchytraeidae were investigated as a part of a broad study of Niepolomice Forest ecosystem functioning. Animals were collected in oak-hornbeam (Tilio-Carpinetum) and in mixed oak-pine (Pino-Quercetum) stands. The highest cadmium concentration was observed in oak-hornbeam from the northern part of the forest (32.33+/-23.22 mg kg(-1) dry mass), with lower ones in mixed oak-pine (13.60+/-21.42 mg kg(-1) dry mass) and southern oak-hornbeam stands (11.84+/-7.52 mg kg(-1) dry mass). Lead concentrations were higher in mixed oak-pine (47.73+/-23.36 mg kg(-1) dry mass) and southern oak-hornbeam (52.20+/-45.19 mg kg(-1) dry mass) stands than in northern, oak-hornbeam (9.20+/-6.46 mg kg(-1) dry mass). The copper concentration was similar in animals from all forest types studied (147.94+/-106.38 mg kg(-1) dry mass in mixed oak-pine, 138.35+/-64.76 mg kg(-1) dry mass in northern oak-hornbeam, and 138.27+/-80.08 mg kg(-1) dry mass in southern oak-hornbeam). The lowest concentration of zinc in animals was found in northern oak-hornbeam (1015.27+/-300.28 mg kg(-1) dry mass) and higher concentrations, in mixed oak-pine (2233.81+/-1825.41 mg kg(-1) dry mass) and southern oak-hornbeam (2366.60+/-1987.52 mg kg(-1) dry mass). The concentrations of available metals in litter trended with those in the animals, but only the relation between lead concentration in animals and available lead in litter was significant. The spatial distribution of metal concentrations in the whole forest suggests a relationship between forest type and the content of cadmium, lead, and zinc in animals. The spatial distribution of heavy metal content in enchytraeids was investigated in selected plots as well. The coefficients of variation indicated that lead had the most diverse distribution and zinc the most homogeneous.  相似文献   

2.
Spatio-temporal variations in sediment quality (20 sample sites) of the Ebro River basin between 2001 and 2011 have been assessed. The self-organizing map classified the sediment samples according to similarities in their chemical compositions. Its powerful visualization tools helped establish the main pollution contribution on each sample. Most of the samples showed low values of the mean-probable effect concentration quotient through time. However, six samples presented several quality issues related to some trace elements or polycyclic aromatic hydrocarbons. Finally, geoaccumulation index values calculated using estimates of background trace element concentrations suggested anthropogenic influences in more than half of the samples.  相似文献   

3.
4.
5.
The objective of the present paper was to verify the occurrence of senile dementia in the city of Fortaleza, Brazil. A screening test, the Information, Memory and Concentration Test (IMC), was applied to 865 persons (65 years old and older). The Test includes questions on personal identification, recent and remote memory and concentration. Dementia was determined as a function of the total score obtained by the person in the test previously examined as far as sensitivity and specificity are concerned. The results were analysed according to age, sex and social strata. It was demonstrated a prevalence of dementia of 8.4% in the sample studied with no significant difference in the proportions of cases among people 75 years old or older (9.3%) as compared to the group younger, 65 to 74 years old, (7.5%). The percentage of dementia was similar between men (8.7%) and women (8.3%). It was verified a progressive increase in the frequency of dementia ranging from 5.2% for the higher social classes (A/B) to 6.9% and 10.3% for medium (C) and lower (D/E) ones respectively, with a significant difference between the social classes A/B and D/E. These results, however, should be seen with caution because of the percentage of refuse especially in the higher, A/B (19.3%) and lower D/E (9.3%) social classes.  相似文献   

6.

Objectives  

To examine if and to what extent ethnic differences in diabetes-related mortality are associated with differences in education and housing status.  相似文献   

7.
Body mass and body composition of 27 adult Velvet Scoters (Melanitta fusca) were studied. These birds were collected from January to March in the Gulf of Gda??sk, Poland. Body mass, fat, and protein contents of both males and females decreased significantly between mid and late winter, possibly because of a physiological process or a result of worsening environmental conditions. In mid-winter, the mean body mass of males and females did not differ significantly, whereas in late winter the difference in body mass between sexes became prominent. There was no difference in fat mass between the sexes, but females had higher lipid indexes despite their smaller size. The lack of expected fat mass increase in late winter may be due to the spring migration strategy of Velvet Scoters, which apparently opt to fly short distances rather than make long non-stop flights after departure from the Gulf of Gda??sk. Body mass was the best predictor of fat mass accumulated by Velvet Scoters wintering in the Gulf of Gda??sk.  相似文献   

8.
9.
10.
Since the signing of the Oslo Peace Accords and the establishment of the Palestinian Authority in 1994, reform activities have targeted various spheres, including the health sector. Several international aid and UN organizations have been involved, as well as local and international non-governmental organizations, with considerable financial and technical investments. Although important achievements have been made, it is not evident that the quality of care has improved or that the most pressing health needs have been addressed, even before the second Palestinian Uprising that began in September 2000. The crisis of the Israeli re-invasion of Palestinian-controlled towns and villages since April 2002 and the attendant collapse of state structures and services have raised the problems to critical levels. This paper attempts to analyze some of the obstacles that have faced reform efforts. In our assessment, those include: ongoing conflict, frail Palestinian quasi-state structures and institutions, multiple and at times inappropriate donor policies and practices in the health sector, and a policy vacuum characterized by the absence of internal Palestinian debate on the type and direction of reform the country needs to take. In the face of all these considerations, it is important that reform efforts be flexible and consider realistically the political and economic contexts of the health system, rather than focus on mere narrow technical, managerial and financial solutions imported from the outside.  相似文献   

11.
12.
13.
14.
15.
INTRODUCTION: There is an apparent gap between physicians' knowledge and their practical application of such knowledge. Educating patients to educate physicians toward improved care has been shown to be effective in selected settings. This study describes the influence of an active community education program on changing physician behavior. METHODS: A total of 672 schoolteachers were interviewed and screened for detection of osteoporosis risk factors. The teachers were educated about osteoporosis and the significance of bone mass densitometry (BMD) in its management and returned to their physicians with the results of their screening. One group of their physicians received didactic lectures on the results of the screening and the impact of appropriate management on the outcome of osteoporosis. The second group of physicians did not. Six months after the initial interview and screening, patients received a mailed survey. RESULTS: After 6 months, 258 of the teachers who had visited their physicians were resurveyed. The percentage of BMD tests ordered by physicians rose from 8.6% to 33% in both the intervention and control physician groups. Findings at the 6-month survey indicated that physicians initiated the osteoporosis discussion an average of 18% of the visits and patients did an average of 60%, prompting the physician to order a BMD test. DISCUSSION: In this study, there was no evidence that didactic lectures affect physician behavior in ordering BMD. There were, however, compelling indications that patient education, which included written screening results, enhanced physician-patient dialogue, resulting in more BMD orders.  相似文献   

16.
The repellency of Nepeta cataria (catmint or catnip) was tested against Aedes aegypti, Ae. vigilax, Culex annulirostris, and Cx. quinquefasciatus, and compared with a blend of natural plant extracts and N,N-diethyl-3-methylbenzamide (deet) on human skin. The catmint and natural plant extract blend did not provide the same level of protection from biting mosquitoes as deet. There were significant differences in the level of protection provided by catmint to the 4 species of mosquito, with mean protection times ranging from 0 min for Ae. aegypti up to 240 +/- 60 min for Cx. quinquefasciatus. Significant differences in the mean landing rates of the 4 mosquito species on untreated forearms highlighted the difficulties in comparing laboratory tests of repellents between species.  相似文献   

17.
Biomass and generic diversity of heterotrophic protists (protozoa) were studied in the near-bottom zone at five stations located in the inner Gulf of Gdańsk and in offshore waters during June 2002. The highest protozoan biomass was observed in the inner Gulf of Gdańsk and close to the mouth of the Vistula River. Protozoan biomass decreased offshore. In well-oxygenated waters heterotrophic flagellates constituted 39–51%, of the protozoan biomass, ciliates constituted 18–25%, and heterotrophic dinoflagellates 29–39% of the protozoan biomass. These findings confirmed previous studies that showed that a high abundance of heterotrophic dinoflagellates is a distinct feature of the Gulf of Gdańsk. At one station located in the Gdańsk Deep, where the near-bottom zone was anoxic, the contribution of heterotrophic flagellates decreased to 18% and ciliates’ share increased to 82% of the protozoan biomass. No dinoflagellates were observed in the anoxic zone.  相似文献   

18.
In this paper we analyse the renal transplant waiting list of the País Valencià in Spain, using Queueing theory. The customers of this queue are patients with end-stage renal failure waiting for a kidney transplant. We set up a simplified model to represent the flow of the customers through the system, and perform Bayesian inference to estimate parameters in the model. Finally, we consider several scenarios by tuning the estimations achieved and computationally simulate the behaviour of the queue under each one. The results indicate that the system could reach equilibrium at some point in the future and the model forecasts a slow decrease in the size of the waiting list in the short and middle term.  相似文献   

19.
20.
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