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2.
A survey of protostelids in ponds of northeastern Germany showed a high degree of similarity between the species assemblages from submerged aquatic and terrestrial litter. Twelve species were recovered from 115 samples. A statistical analysis of species accumulation curves indicated that 90 % of the total diversity was recovered for both aquatic and terrestrial litter. All of the more common species were observed in both aquatic and terrestrial samples. However, 24 % of all cultures from terrestrial samples were positive for protostelids, compared with only 12 % for aquatic samples. An additional 20 samples collected from the water column did not yield any protostelids. The study indicates that vegetative stages of most protostelids seem to be able to survive and probably multiply on litter submerged in fresh water, but do not live as plankton. Most probably, submerged substrata are sinks for protostelid populations. 相似文献
4.
Background: The adobe bricks of old buildings can preserve diaspores of cultivated and weed species associated with arable fields. Recovery of these plant remains can provide insight into historical agriculture, and former weed flora. Aims: This study aims to describe and evaluate the changes in the weed flora in south-western Hungary, based on archaeobotanical findings and contemporary plot surveys. Methods: Plant remains of 51 adobe bricks dating from 1850 to 1950 were identified in south-western Hungary and compared with the flora of 104 plots from the same region. Results: A total of 276 species were identified from the adobe bricks, while the present-day plot survey yielded 305 species. A significant difference was found between the historical (60- to 160-year-old) and current species richness of the weed flora. The proportion of rare and threatened species decreased by 38.1%. A total of 142 weed species identified from the adobe bricks have declined, and 40 of them even disappeared in comparison with the contemporary surveys. Today, in Hungary and neighbouring countries, more than 80 of these species are rare or threatened and some of them are extinct or critically endangered. Conclusions: Our findings show that many weed species that flourished in the early twentieth century have declined. This is most likely due to the intensive management practices of cultivated fields and the spread of invasive neophyte taxa. We showed that analysing the botanical information preserved in adobe bricks is a reliable method that can provide evidence of long-term changes in weed flora. 相似文献
5.
We studied the changes of exergy and specific exergy with data of benthic macrofauna communities, periodically sampled along an estuarine gradient of eutrophication in the Mondego estuary (Western Portugal). Exergy estimates were calculated from organism biomass, based on weighing factors for the relative content of exergy per unit of biomass determined from DNA contents of organisms. Results were discussed in terms of both the macrofauna biomass production and the structural organisation of the system. Estimates for the exergy indices provided useful indications for the evaluation of environmental impact due to the eutrophication process. Different average values for the indices of exergy and specific exergy were estimated relatively to areas with different levels of eutrophication, in the spatial gradient of eutrophication. Higher exergy levels and lower exergy content per unit of biomass (specific exergy) were associated to populations more stabilized or areas less perturbed. Additionally, the index of specific exergy seemed capable of providing indications for the qualitative alterations in the communities (in temporal and spatial terms) that go in the direction of the observations made in this ecosystem. 相似文献
6.
BackgroundTakotsubo cardiomyopathy (TTC) is characterised by transient contractility disturbances of the apex of the left ventricle.MethodsWe enrolled 101 patients from the northern-eastern part of Poland in the years 2008–2012 who were hospitalised for TCC. The control group consisted of female patients diagnosed with anterior myocardial infarction with ST-segment elevation (anterior STEMI) (n = 101).Results89?% of the study group were women. Patients with TTC had diabetes (12.6?% vs 29.7?%; p = 0.002) and hyperlipidaemia (36.8?% vs 64.4?%; p = 0.0001) significantly less frequently, and better kidney function assessed by estimated glomerular filtration rate versus patients with anterior STEMI (74.52?% vs 64.30?%; p = 0.004). In the TTC group there were more patients with chronic obstructive pulmonary disease (11.6?% vs 1.0?%; p = 0.002) and thyroid disturbances, especially hyperthyroidism (23.4?% vs 11.0?%; p = 0.021). In patients with TTC sudden cardiac arrest, pulmonary oedema and cardiogenic shock were observed less frequently than in the control group (14.7?% vs 30.7?%; p = 0.0078). Hospitalisations in TTC patients were less frequently complicated by pneumonia (20.0?% vs 35.6?%; p = 0.0148) and urinary infection (4.2?% vs 21.8?%; p = 0.0003). Cardiac rupture occurred in 3 patients with TTC and in 1 with anterior STEMI. In-hospital mortality was significantly lower in the group with TTC. Also, mortality at 30 days, 3 months, 1 year and 2.5 years was significantly lower in patients with TTC than in patients with MI (p = 0.035; p = 0.0226; p = 0.0075; p = 0.009).ConclusionsPreviously considered to be a benign syndrome, TTC should be reconsidered as a clinical condition at risk for serious complications such as cardiac arrest, cardiogenic shock, pulmonary oedema and cardiac rupture leading to death and causing substantial early hazard. The prognosis in TTC is significantly better than in patients with anterior STEMI. 相似文献
9.
Numerous variations to a manufacturing process may take place during the life cycle of a vaccine. To support these variations, the regulator requires providing stability data according to the existing ICH guidelines; these have been designed for documenting the licence of a new vaccine. Comparative studies and adapted stability designs specific to the variation will give far more confidence to the manufacturer and the regulator than the classical model. The following case study applied to a change of a stopper illustrates this approach. 相似文献
10.
This paper presents the results of an extensive and detailed survey conducted in 1985 on the biology, bacteriology and levels of heavy metals in subtidal sediments of the Humber estuary. The findings of the investigation are assessed with respect to environmental quality. Abundance and distribution patterns of the indicator species Capitella capitata, the numbers of faecal bacteria, and levels of heavy metals and organic matter are examined in relation to areas of sewage disposal. The possible effects of inputs from the Humber to the North Sea are discussed. 相似文献
11.
From the ninth century, when the first settlers came, until 1262 when it ceased to exist, the Icelandic Commonwealth was a stratified society without a state. There developed a class of independent householders who appropriated the production of a class of landless people. The householders gained access to land by supporting a class of chieftains who guaranteed their access by force. Each chieftain had to attempt to muster overwhelming force by expansion. This led to a period of conflict that ended when one chieftain was successful in gaining control of the island in the context of Norwegian royal hegemony. The collapse of the Commonwealth was not due to the introduction of Christianity, cultural changes, or Norwegian manipulation, but to the internal contradictions of a stratified society without a state. 相似文献
13.
Seed dispersal is a mutualistic interaction in which frugivores gain nutrients and plants gain when seeds are transported
to adequate places for establishment. However, this relationship is prone to deceit, for example, when frugivores spit-out
seeds in the proximity of parental trees. Still, few hypotheses have offered explanations on why deceiving strategies are
not widespread. In this study, I explore the importance of how difficult it is to mechanically separate the nutritious pulp
from the seeds, as a factor that can explain the chance a seed has of being dispersed by woolly monkeys ( Lagothrix lagothricha). I completed 1,440 h of focal animal follows during 2 years in order to quantify the chances plant species have of being
dispersed. To do so, I evaluated the residuals from the relationship between the number of seeds manipulated and seeds dispersed
by a population of woolly monkeys in Tinigua Park (Colombia). For 74 fruit species, I estimated how difficult it is to separate
pulp from seeds as the time needed to separate the parts. An exponential model showed that this variable was able to predict
38% of the variation on dispersal probability, demonstrating that, when it is difficult to separate the pulp from the seeds,
the probability of legitimate dispersal increases. However, when fruit parts were easy to separate, there was more variation
in the outcome. My results suggest that many plants have evolved mechanisms (e.g., small seeds embedded in pulp, strong attachment,
irregular seed surface, and thin pulp layer) that preclude deceit by frugivores. 相似文献
15.
A greater emphasis in school curricula on the technology of science would encourage teachers to engage their students more in practical work. This in turn might be expected to improve students’ attitudes towards science and enhance cognitive outcomes. The paper presents findings from a study on first-year university students’ school experience of, attitudes towards, and knowledge of, microscopy. The findings reinforce the general expectations alluded to above. They also draw attention to the importance of the lower secondary science experience – often a suboptimal one owing to a poor resource base – to the formation of student attitudes and cognitive development with respect to science. 相似文献
17.
Conventional as well as molecular techniques have been used to determine the microbial communities present on the concrete walls of sewer pipes. The genetic fingerprint of the microbiota on corroded concrete sewer pipes was obtained by means of denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. The DGGE profiles of the bacterial communities present on the concrete surface changed as observed by shifts occurring at the level of the dominance of bands from non-corroded places to the most severely corroded places. By means of statistical tools, it was possible to distinguish two different groups, corresponding to the microbial communities on corroded and non-corroded surfaces, respectively. Characterization of the microbial communities indicated that the sequences of typical bands showed the highest level of identity to sequences from the bacterial strains Thiobacillus thiooxidans, Acidithiobacillus sp., Mycobacterium sp. and different heterotrophs belonging to the alpha-, beta- and gamma-Proteobacteria, Acidobacteria and Actinobacteria. In addition, the presence of N-acyl-homoserine lactone signal molecules was shown by two bio-assays of the biofilm on the concrete under the water level and at the most severely corroded places on the concrete surface of the sewer pipe. 相似文献
18.
We investigated the changes of water level and vegetation in a restored cut-over raised bog in response to a hydrological
protection zone established around the bog. The restoration began 1997 and techniques involved ditch blocking within and around
the bog to stimulate a return to conditions of intact bog ecosystems. In order to monitor the rehabilitation of the raised
bog, water levels and vegetation have been recorded since before restoration measures began. The monitoring is ongoing, but
an assessment of 15 year’s data (1994–2008) is presented. A hydrological protection zone with continuous high water levels
could be established around the raised bog which minimizes the runoff of precipitation. Shortly after the first measures,
the water levels increased significantly at all dipwells. Parallel to the increasing water levels a vascular plant species
assemblage and a diverse Sphagnum community developed. In particular Sphagnum fimbriatum, S. palustre, S. recurvum and S. squarrosum spread efficiently. The cover of trees decreased significantly because of high water levels and ongoing acidification by
Sphagnum spp. The high water levels have stimulated the re-vegetation and the hydrology self-regulation of the acrotelm. The successful
regeneration of the acrotelm particularly became apparent in years with below-average precipitations (e.g. 2008), when the
water levels in the central parts of the raised bog did not fall back to the low level reached in previous years, which had
also remarkably water deficits (e.g. 2003). 相似文献
19.
Environmental Biology of Fishes - 相似文献
20.
PurposeThis research determines the extent to which farmers benefit from agricultural extension activities and services through realizing higher biological crop yields in the Al-Baha region of the Kingdom of Saudi Arabia. Additionally, the nature of the relationship between the personal, economic and social characteristics of farmers and the degree to which they benefit from agricultural extension activities and services are studied. MethodologyA simple random sample representing the community of 315 farmers was drawn. Data were collected through a personal interview with a pre-tested questionnaire to satisfy the objectives of the study. Data are subjected to analyses and are interpreted in terms of percentages, arithmetic averages, and standard deviations in addition to the simple Pearson correlation coefficients. ResultsThe results show that most of the respondents depend on personal experience, friends, family and neighbors, merchants and sellers of agricultural production supplies as sources of agricultural information for enhanced crop yields. Multiple regression analysis reveals that both the educational status and the agricultural information sources are important factors that increase farmers benefit from extension activities. Farmers receive most benefits from the extension activities and services from bringing in foreign workers, conducting field trips to farms, and identifying problems faced by farmers. Research limitations/implicationsThe outcome of this questionnaire limits generalization of the findings for other parts of the Kingdom due to geographical and natural resources variations. Practical implicationsThe personal and socio-economic characteristics of the surveyed population provide the extension service with insight into their composition – a basis to formulate workable extension programs. For the extension planners of the area, this effort provides a baseline study and may assist with targeting the appropriate farmers and catering the right solutions to the problems. Such a study will help devise meaningful extension programs and save time and resources. Originality/valueLittle previous research on the usefulness of the Extension Service has been conducted in the region. ConclusionsEffective, well-planned extension programs targeting the educated and mature farmers provided more benefits and helped them obtain higher crop yields. 相似文献
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