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1.
Stroke occurrence shows strong correlations with sleep disorders and even subtle sleep disturbances have been shown to affect ischemic stroke (IS) occurrence. Chronobiology also exerts effects, like the morning surge in IS occurrence. Lunar cycles have also been shown to affect sleep and other physiological processes, but studies on moon phases and its possible association with occurrence of stroke are rare and nonconclusive. Therefore, we studied the effects of moon phases on stroke hospitalizations and in-hospital mortality nationwide in Finland in 2004–2014. All patients aged ≥18 years with IS or intracerebral hemorrhage (ICH) as primary discharge diagnosis were included. Daily number of admissions was treated as a response variable while moon phase, year and astronomical season were independent variables in Poisson regression modeling. We found no association between moon phases and stroke occurrence. The overall occurrence rates did not vary between different moon phases for IS or ICH (p = 0.61 or higher). There were no differences between moon phases in daily admission rates among men, women, young and old patients for any of the stroke subtypes. There was no difference in in-hospital mortality with regard to moon phase for IS or ICH overall (p = 0.19 or higher), nor in subgroup analyses. There were no significant interactions between moon phase and astronomical season for stroke occurrence or in-hospital mortality. To conclude, in this over a decade-long nationwide study including a total of 46 million person years of follow-up, we found no association between moon phases and occurrence or in-hospital mortality rates of IS or intracerebral hemorrhage.  相似文献   

2.
We have performed a statistical analysis of unstructured amino acid residues in protein structures available in the databank of protein structures. Data on the occurrence of disordered regions at the ends and in the middle part of protein chains have been obtained: in the regions near the ends (at distance less than 30 residues from the N- or C-terminus), there are 66% of unstructured residues (38% are near the N-terminus and 28% are near the C-terminus), although these terminal regions include only 23% of the amino acid residues. The frequencies of occurrence of unstructured residues have been calculated for each of 20 types in different positions in the protein chain. It has been shown that relative frequencies of occurrence of unstructured residues of 20 types at the termini of protein chains differ from the ones in the middle part of the protein chain; amino acid residues of the same type have different probabilities to be unstructured in the terminal regions and in the middle part of the protein chain. The obtained frequencies of occurrence of unstructured residues in the middle part of the protein chain have been used as a scale for predicting disordered regions from amino acid sequence using the method (FoldUnfold) previously developed by us. This scale of frequencies of occurrence of unstructured residues correlates with the contact scale (previously developed by us and used for the same purpose) at a level of 95%. Testing the new scale on a database of 427 unstructured proteins and 559 completely structured proteins has shown that this scale can be successfully used for the prediction of disordered regions in protein chains.  相似文献   

3.
W.S.G. Maass 《Phytochemistry》1975,14(11):2487-2489
In addition to tenuiorin, methyl gyrophorate and methyl evernate have been isolated from Peltigera aphthosa. The occurrence of a tetradepside (aphthosin) in all the specimens investigated of this species has not been verified.  相似文献   

4.
Occurrence of 7-methylguanine in nucleic acids of rat liver   总被引:8,自引:8,他引:0       下载免费PDF全文
1. Microsomal and soluble RNA of rat liver have been studied by column and paper chromatography after administration of [Me-(14)C]methionine; evidence was obtained for the occurrence of 7-methylguanine, the methyl group being derived from methionine. 2. No evidence was obtained for the occurrence of 7-methylguanine in DNA.  相似文献   

5.
The Widespread Occurrence of Polyphosphate in Lower Plants   总被引:2,自引:0,他引:2  
KECK  K.; STICH  H. 《Annals of botany》1957,21(4):611-619
The widespread occurrence of polyphosphate (PoP) in lower plantsis described. PoP granules have been cytochemically detectedin algae, slime moulds, and mosses. A systematic survey is givenof lower plants in which the occurrence of PoP has been demonstratedwith both the present studies and previous investigations. The localization of PoP in cells has been studied. PoP granuleshave been observed to be present in the cytoplasm, the cytoplasmicvacuole, and in chloro-plasts of different algae. In Zygnemataceaeand in mosses PoP granules are localized in the chloroplastswhich also contain pentose nucleic acid. A relationship between PoP, pentose nucleic acid (PNA), andgrowth has been found and is discussed. A possible in situ synthesisof PoP in chloroplasts from phosphorylated intermediates ofthe photosynthetic process is suggested.  相似文献   

6.
Two glutamylselenocystathionines have been isolated from the seeds of Astragalus pectinatus. These have been identified as 2-γ-glutamylamino-4-(2-amino-2-carboxyethylselenyl) butyric acid and 2-amino-4-(2-γ-glutamylamino-2-carboxyethylselenyl) butyric acid. The evidence for the natural occurrence of the corresponding glutamylcystathionines is also presented.  相似文献   

7.
随着转基因植物的大面积种植,转基因植物的生态风险受到广泛关注,其中主要的风险是转基因植物与近缘物种之间的基因流及其影响。本文综述了目前商业化种植的转基因作物油菜、棉花、玉米和大豆,以及未商业化种植的水稻、小麦的基因流研究进展;分析了不同转基因作物与其近缘种之间发生基因流的频率和最远发生距离;介绍了降低基因流发生的方法。基因流频率受物种亲缘关系、花期重叠时间、风速风向等因素的影响,最远发生距离受气候条件、传粉媒介、地理条件等因素的影响。转基因作物与其近缘种之间的基因流频率与距花粉源的距离呈负相关关系(y=-0.59x-0.46,R2=0.25,P<0.01),亲缘关系近的基因流频率高。为了降低转基因植物与其近缘物种之间的基因流风险,建议采取“分区管理”的策略,并加强基因流发生之后的生态风险评价研究。  相似文献   

8.
The silver carp and bighead carp (Cyprinidae), native to eastern Asia, have been introduced into the United States in attempts to improve water quality in aquaculture ponds, reservoirs, and sewage pools. Escaped or released specimens from fish farms have been reported in many states, and both species are already locally established and spreading further. We used the Genetic Algorithm for Rule-set Prediction (GARP) to model the niches of these two carps in their native ranges using hydrologic and general environmental parameters in concert with native distributional data. The results accurately predicted native occurrence data withheld from the modeling process (P < 0.01). We then projected the niche models onto the North American landscape. Native niche range models significantly predicted known occurrence data from North American introductions (P < 0.001). Further, the models suggest that both species have the potential of spreading throughout the eastern U.S. and selected areas of the West Coast.  相似文献   

9.
The southern coast of Baikal is characterized by the most humid climate in the Baikal region. Precipitation falls mainly on summer, thus reducing the actual of fire occurrence in mountain forests of the region. However, since 1989 the fire occurrence has been increased and disastrous crown fires have become more frequent, especially in the west. It is shown that fire occurrence is a function of the number, duration of rainless periods and monthly sums of rain precipitation, which have large amplitude of changes from year to year. Progressive pyrogenic successions in dark coniferous forests take place mostly without usual replacement by small-leaved tree species at the expense of successful regeneration of Pinus sibirica (in the western Khamar-Daban mountains) and Abies sibirica (in the central part) on the burnt areas during 15–25 years.  相似文献   

10.
In Upper Pliocene/lowermost Pleistocene marine sediments of SE-Lakonia (Greece) shell fragments ofTestudo marginata have been found. The taxonomic determination of this possibly earliest occurrence has been proved by the morphological identity with the recentTestudo marginata.  相似文献   

11.
Much debate has surrounded the notion that outbreaks of the crown-of-thorns starfish (Acanthaster planci) have occurred in the geological past and hence are natural phenomena. As this debate has recently been renewed, we have reassessed statistically data presented by Frankel (1977, 1978) as evidence for the occurrence of past outbreaks. This was done using Frankel's data as well as those from extensive starfish surveys conducted prior to the commencement of his research. Our analysis of these data indicates that the occurrence of A. planci remains in recent sediments is independent of whether or not the reef from which the sample was collected had experienced a recent outbreak. Based on this premise, it is not possible to infer from Frankel's data the occurrence of past outbreaks from similar material in much older sediments. Thus while the data presented by Frankel (1977, 1978) may show that A. planci has existed within the Great Barrier Reef for at least several thousand years it does not demonstrate that outbreaks of this starfish have occurred in the geological past.  相似文献   

12.
M. F. Large  J. E. Braggins 《Grana》2013,52(2):125-127
Both tetralete and trilete spores have been found in New Zealand material of A. hispidulum Swartz. The rare tetralete spores are associated with the occurrence of spore pentads and hexads (post meiosis), and have the same sculptural pattern (finely pitted) as the trilete spores but are smaller with laesurae being often less distinct.  相似文献   

13.
Pacific chub, Kyphosus sandwicensis, are typically gray but some individuals display a golden color morph. We estimated that the frequency of occurrence of the golden morphs increased significantly from 2007 (1.9%) and 2012 (2.6%) to 2017 (5.0%) inside a no-take marine reserve around Nihoa Island in the Northwestern Hawaiian Islands. While sporadic observations of a golden color morph have been noted for several other marine fish species, we provide a quantitative estimate of changes in the frequency of occurrence of the morph within a wild marine population.  相似文献   

14.
Summary Since 1937 we have been aware of the occurrence of the subterranean termite Reticulitermes in Hamburg; this was probably introduced from the U.S.A. Control of this dangerous wood-destroying insect was carried out between 1954 and 1961. In 1966 the same termite species was found in Munich and control started immediatly. During this control work there was occasion to observe and to investigate some ecological factors such as correlation between temperature and termite infestation, the occurrence of winged termites (primary sexual stages), and the nutrition requirements (dead and living wood).  相似文献   

15.
During recent years, predictive modelling techniques have been increasingly used to identify regional patterns of species spatial occurrence, to explore species–habitat relationships and to aid in biodiversity conservation. In the case of birds, predictive modelling has been mainly applied to the study of species with little variable interannual patterns of spatial occurrence (e.g. year‐round resident species or migratory species in their breeding grounds showing territorial behaviour). We used predictive models to analyse the factors that determine broad‐scale patterns of occurrence and abundance of wintering Swainson's hawks (Buteo swainsoni). This species has been the focus of field monitoring in its wintering ground in Argentina due to massive pesticide poisoning of thousands of individuals during the 1990s, but its unpredictable pattern of spatial distribution and the uncertainty about the current wintering area occupied by hawks led to discontinuing such field monitoring. Data on the presence and abundance of hawks were recorded in 30 × 30 km squares (n = 115) surveyed during three austral summers (2001–03). Sixteen land‐use/land‐cover, topography, and Normalized Difference Vegetation Index (NDVI) variables were used as predictors to build generalized additive models (GAMs). Both occurrence and abundance models showed a good predictive ability. Land use, altitude, and NDVI during spring previous to the arrival of hawks to wintering areas were good predictors of the distribution of Swainson's hawks in the Argentine pampas, but only land use and NDVI were entered into the model of abundance of the species in the region. The predictive cartography developed from the models allowed us to identify the current wintering area of Swainson's hawks in the Argentine pampas. The highest occurrence probability and relative abundances for the species were predicted for a broad area of south‐eastern pampas that has been overlooked so far and where neither field research nor conservation efforts aiming to prevent massive mortalities has been established.  相似文献   

16.
The larvae of some species of Dermestidae (Coleoptera) are able to bore the bones of a carrion for pupation. Several pupal chambers have been observed on an unciform belonging to a fossil rhinocerotid (Mesaceratherium sp.) from the late Oligocene/earliest Miocene of the phosphorites of Quercy (SW France). Such an unusual observation demonstrates the occurrence of dermestids in the entomofauna of the phosphorites of Quercy, and suggests at least the existence of paleoclimatic episodes with dry seasons, during a period usually considered as a relatively humid one. This is the earliest occurrence of such ichnofossils on a fossil mammal bone.  相似文献   

17.
Poysa  Hannu 《Behavioral ecology》2006,17(3):459-465
Conspecific nest parasitism (CNP) is a widespread alternativereproductive tactic in birds. Several hypotheses have been putforward to explain the evolution and occurrence of CNP, butno generally applicable hypothesis exists. Recent experimentalresults from the common goldeneye (Bucephala clangula), a cavity-nestingduck, have revealed that parasitic females preferentially layeggs in safe nest-sites, implying that nest predation risk isan important ecological determinant of CNP. The present studyfocuses on the mechanisms by which parasites identify safe nest-sites.Predation risk of a given nest-site was predictable betweensuccessive breeding seasons. At the end of the nesting season,females prospected active nest-sites more frequently than nest-sitesthat did not have a nest in the current season. Nest-sites thathad been prospected more frequently by females in year t hada higher probability to be parasitized in year t + 1. The resultssuggest that the use of public information, derived throughnest-site prospecting, enabled parasites to target safe nests.These findings provide a new and potentially generally applicableperspective to understand the evolution and occurrence of CNP.  相似文献   

18.
E. Orlando 《Genetica》1983,62(1):55-59
Pairing stages of homologous chromosomes suggesting the occurrence of an endomeiotic process during the maturation of parthenogenetic oocytes have been found in Megoura viciae. This study underlines the importance of these synaptic stages as far as the determination of the male sex is concerned. Maturation divisions with 8 chromosomes (6 univalents + 2 bivalents) instead of 9 chromosomes (1 bivalent XX + 8 autosomes) have been found in males-producing eggs. The presence of these two bivalents causes aneuploidy in male embryos and probably abortion.  相似文献   

19.
The frequency of occurrence and seasonal periodicity of aquatic hyphomycetes in a temperate freshwater stream of Central Himalaya were studied. The number of aquatic hyphomycetes species was found to vary inversely with temperature (r= −0.499; not significant), which explained 25 % of the variability. There were two maxima, one in spring and the other in autumn. On the basis of their occurrence, the species observed have been categorised into three groups. Constant species were Campylospora chaetocladia, Flagellospora penicilloides, Lemonniera aquatica and Tetracladium marchalianum.  相似文献   

20.
Ranaviruses are causing mass amphibian die-offs in North America, Europe and Asia, and have been implicated in the decline of common frog (Rana temporaria) populations in the UK. Despite this, we have very little understanding of the environmental drivers of disease occurrence and prevalence. Using a long term (1992-2000) dataset of public reports of amphibian mortalities, we assess a set of potential predictors of the occurrence and prevalence of Ranavirus-consistent common frog mortality events in Britain. We reveal the influence of biotic and abiotic drivers of this disease, with many of these abiotic characteristics being anthropogenic. Whilst controlling for the geographic distribution of mortality events, disease prevalence increases with increasing frog population density, presence of fish and wild newts, increasing pond depth and the use of garden chemicals. The presence of an alternative host reduces prevalence, potentially indicating a dilution effect. Ranavirosis occurrence is associated with the presence of toads, an urban setting and the use of fish care products, providing insight into the causes of emergence of disease. Links between occurrence, prevalence, pond characteristics and garden management practices provides useful management implications for reducing the impacts of Ranavirus in the wild.  相似文献   

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