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1.
The success rate of nonsurgical embryo recovery was influenced neither by year nor by season within years. The preferred method of nonsurgical embryo transfer was by Cassou pistolette. From a total of 15 attempts to transfer embryos nonsurgically, 9 (60%) were successful. Of the five attempts during February through April 1982, only one was successful in producing a live foal. The degree of synchrony between the ovulations of the donors and recipients in these five attempts ranged from +3 to -3 d. The recipient of the successful transfer ovulated on the same day as the donor. Eight of the ten attempts during September through December 1982 produced live foals. Synchronization of ovulations between the donors and recipients in these transfers ranged from 0 to -2 d. Repeated attempts to recover embryos had no deleterious effects on fertility of the donors. 相似文献
2.
In the spring of 1974 the migration and spawning behaviour of barbel, Barbus barbus (L.) were observed. The migration and behaviour of males prior to the spawning attempts may be strategies designed to increase the quota of receptive females experienced by each male. Spawning attempts were divided into two categories: successful and failed. Successful attempts comprised six sequential sub-events: approach period, pre-spawning phase, spawning, post-spawning phase, dispersal period and inter-spawning period. The spawning and post-spawning phases did not occur in a failed attempt. The success or failure of attempts was dependent upon the number of males present. The advantage gained by females abandoning attempts when the male densities were high is discussed. In both the pre-spawning phase of failed attempts and the post-spawning phase of successful attempts, males attempted to drive away other male competitors by the use of male 'chase away' interactions. 相似文献
3.
Genetic and phenotypic variation in female response towards male mating attempts has been found in several laboratory studies, demonstrating sexually antagonistic co-evolution driven by mating costs on female fitness. Theoretical models suggest that the type and degree of genetic variation in female resistance could affect the evolutionary outcome of sexually antagonistic mating interactions, resulting in either rapid development of reproductive isolation and speciation or genetic clustering and female sexual polymorphisms. However, evidence for genetic variation of this kind in natural populations of non-model organisms is very limited. Likewise, we lack knowledge on female fecundity-consequences of matings and the degree of male mating harassment in natural settings. Here we present such data from natural populations of a colour polymorphic damselfly. Using a novel experimental technique of colour dusting males in the field, we show that heritable female colour morphs differ in their propensity to accept male mating attempts. These morphs also differ in their degree of resistance towards male mating attempts, the number of realized matings and in their fecundity-tolerance to matings and mating attempts. These results show that there may be genetic variation in both resistance and tolerance to male mating attempts (fitness consequences of matings) in natural populations, similar to the situation in plant-pathogen resistance systems. Male mating harassment could promote the maintenance of a sexual mating polymorphism in females, one of few empirical examples of sympatric genetic clusters maintained by sexual conflict. 相似文献
4.
Background
To investigate the epidemiology of a steep decrease in the incidence of suicide deaths in Australia.Methods
National data on suicide deaths and deliberate self-harm for the period 1994–2007 were obtained from the Australian Institute of Health and Welfare. We calculated attempt and death rates for five major methods and the lethality of these methods. Negative binomial regression was used to estimate the size and significance of method-specific time-trends in attempts and lethality.Results
Hanging, motor vehicle exhaust and firearms were the most lethal methods, and together accounted for 72% of all deaths. The lethality of motor vehicle exhaust attempts decreased sharply (RR = 0.94 per year, 95% CI 0.93–0.95) while the motor vehicle exhaust attempt rate changed little; this combination of motor vehicle exhaust trends explained nearly half of the overall decline in suicide deaths. Hanging lethality also decreased sharply (RR = 0.96 per year, 95% CI 0.956–0.965) but large increases in hanging attempts negated the effect on death rates. Firearm lethality changed little while attempts decreased.Conclusion
Declines in the lethality of suicide attempts–especially attempts by motor vehicle exhaust and hanging–explain the remarkable decline in deaths by suicide in Australia since 1997. 相似文献5.
While studies of sexual selection focus primarily on female choice and male-male competition, males should also exert mate choice in order to maximize their reproductive success. We examined male mate choice in mosquitofish, Gambusia holbrooki, with respect to female size and female dominance. We found that the number of mating attempts made by a male was predicted by the dominance rank of females in a group, with dominant females attracting more mating attempts than subordinates. The number of mating attempts made by males was independent of the female size. The observed bias in the number of mating attempts towards dominant females may be driven either by straightforward male mate choice, since dominance and female fecundity are often closely related, or via the dominant females mediating male mating behaviour by restricting their access to subordinate females. 相似文献
6.
The organism associated with EPM is a protozoan. It bears greatest resemblance to the genus Sarcocystis based on the mode of replication, staining characteristics, location in host cells, serology and epidemiology. However, attempts to produce the disease in equids by oral inoculation with many species of Sarcocystis have been unsuccessful. Because the distribution of EPM is limited to North America, further attempts to identify the organism and its source should focus on animal sources unique to that continent. 相似文献
7.
Thomas Cornulier David A. Elston Peter Arcese Tim G. Benton David J.T. Douglas Xavier Lambin Jane Reid Robert A. Robinson William J. Sutherland 《Ecology letters》2009,12(11):1184-1193
Well-established statistical methods exist to estimate variation in a number of key demographic rates from field data, including life-history transition probabilities and reproductive success per attempt. However, our understanding of the processes underlying population change remains incomplete without knowing the number of reproductive attempts individuals make annually; this is a key demographic rate for which we have no satisfactory method of estimating. Using census data to estimate this parameter from requires disaggregating the overlying temporal distributions of first and subsequent breeding attempts. We describe a Bayesian mixture method to estimate the annual number of reproductive attempts from field data to provide a new tool for demographic inference. We validate our method using comprehensive data on individually-marked song sparrows Melospiza melodia , and then apply it to more typical nest record data collected over 45 years on yellowhammers Emberiza citrinella . We illustrate the utility of our method by testing, and rejecting, the hypothesis that declines in UK yellowhammer populations have occurred concurrently with declines in annual breeding frequency. 相似文献
8.
Marina Economou Michael Madianos Lily Evangelia Peppou Christos Theleritis Athanasios Patelakis Costas Stefanis 《World psychiatry》2013,12(1):53-59
The financial crisis in Greece is largely impinging on the health and mental health of the population, raising concerns about a potential rise in suicide rates. The aim of this study was to explore changes in suicidal ideation and reported suicide attempts between 2009 and 2011 in a representative sample of the population and in several population subgroups. The socio‐economic predictors of suicidal ideation and suicide attempts in 2011 were also investigated. Two nationwide cross‐sectional telephone surveys were conducted in 2009 and 2011 using the same methodology. A random and representative sample of 2192 and 2256 people, respectively, took part in the surveys. Between 2009 and 2011, there was a substantial increase in the prevalence of suicidal ideation and reported suicide attempts. People suffering from depression, men, married individuals, people experiencing financial strain, people with low interpersonal trust, and individuals with a history of suicide attempts were particularly vulnerable. 相似文献
9.
Axel Meyer 《Ethology : formerly Zeitschrift fur Tierpsychologie》1988,78(3):199-208
The response to a novel prey item was investigated during the first month of feeding of the cichlid fish Cichlasoma managuense. The relative contribution of size and age to improvement in predatory behavior was addressed. Group I (control) was fed nauplii of Artemia salina and group II a manufactured flakefood diet. Group II fish were tested for their ability to prey on a novel diet, the nauplii of Artemia salina. Latency to respond to the presence of novel prey decreased and the number of capture attempts increased with increasing experience with the artificial diet and with age. As size increased so did the number of capture attempts, but the latency did not change. Size and experiential and maturational factors may affect parts of the predatory behavior differentially. During the first month of feeding, age may be more important than size for the decrease in latency and the increase in the number of capture attempts. The number of capture attempts during the first 30 s of the observation period and the capture success increased faster than the latency decreased. Latency to respond to novel prey may mature at a slower rate than the number of capture attempts. 相似文献
10.
Heraldo L. Vasconcelos Ernane H. M. Vieira‐Neto Fabiane M. Mundim Emilio M. Bruna 《Biotropica》2006,38(5):661-665
Roads can facilitate the establishment and spread of both native and exotic species. Nevertheless, the precise mechanisms facilitating this expansion are rarely known. We tested the hypothesis that dirt roads are favorable landing and nest initiation sites for founding‐queens of the leaf‐cutter ant Atta laevigata. For 2 yr, we compared the number of attempts to found new nests (colonization attempts) in dirt roads and the adjacent vegetation in a reserve of cerrado (tree‐dominated savanna) in southeastern Brazil. The number of colonization attempts in roads was 5 to 10 times greater than in the adjacent vegetation. Experimental transplants indicate that founding‐queens are more likely to establish a nest on bare soil than on soil covered with leaf‐litter, but the amount of litter covering the ground did not fully explain the preference of queens for dirt roads. Queens that landed on roads were at higher risk of predation by beetles and ants than those that landed in the adjacent vegetation. Nevertheless, greater predation in roads was not sufficient to offset the greater number of colonization attempts in this habitat. As a consequence, significantly more new colonies were established in roads than in the adjacent vegetation. Our results suggest that disturbance caused by the opening of roads could result in an increased Atta abundance in protected areas of the Brazilian Cerrado. 相似文献
11.
During observations of the River Ourthe, Belgium, 70 spawning attempts were recorded during the reproductive period of the European grayling. Thirty-six per cent of the spawning attempts proceeded to completion, while interference by another male may explain some of the incomplete acts. Sneaking behaviour was observed and one spawning act included two males and one female. 相似文献
12.
Matthew K. Nock Irving Hwang Nancy Sampson Ronald C. Kessler Matthias Angermeyer Annette Beautrais Guilherme Borges Evelyn Bromet Ronny Bruffaerts Giovanni de Girolamo Ron de Graaf Silvia Florescu Oye Gureje Josep Maria Haro Chiyi Hu Yueqin Huang Elie G. Karam Norito Kawakami Viviane Kovess Daphna Levinson Jose Posada-Villa Rajesh Sagar Toma Tomov Maria Carmen Viana David R. Williams 《PLoS medicine》2009,6(8)
Background
Suicide is a leading cause of death worldwide. Mental disorders are among the strongest predictors of suicide; however, little is known about which disorders are uniquely predictive of suicidal behavior, the extent to which disorders predict suicide attempts beyond their association with suicidal thoughts, and whether these associations are similar across developed and developing countries. This study was designed to test each of these questions with a focus on nonfatal suicide attempts.Methods and Findings
Data on the lifetime presence and age-of-onset of Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) mental disorders and nonfatal suicidal behaviors were collected via structured face-to-face interviews with 108,664 respondents from 21 countries participating in the WHO World Mental Health Surveys. The results show that each lifetime disorder examined significantly predicts the subsequent first onset of suicide attempt (odds ratios [ORs] = 2.9–8.9). After controlling for comorbidity, these associations decreased substantially (ORs = 1.5–5.6) but remained significant in most cases. Overall, mental disorders were equally predictive in developed and developing countries, with a key difference being that the strongest predictors of suicide attempts in developed countries were mood disorders, whereas in developing countries impulse-control, substance use, and post-traumatic stress disorders were most predictive. Disaggregation of the associations between mental disorders and nonfatal suicide attempts showed that these associations are largely due to disorders predicting the onset of suicidal thoughts rather than predicting progression from thoughts to attempts. In the few instances where mental disorders predicted the transition from suicidal thoughts to attempts, the significant disorders are characterized by anxiety and poor impulse-control. The limitations of this study include the use of retrospective self-reports of lifetime occurrence and age-of-onset of mental disorders and suicidal behaviors, as well as the narrow focus on mental disorders as predictors of nonfatal suicidal behaviors, each of which must be addressed in future studies.Conclusions
This study found that a wide range of mental disorders increased the odds of experiencing suicide ideation. However, after controlling for psychiatric comorbidity, only disorders characterized by anxiety and poor impulse-control predict which people with suicide ideation act on such thoughts. These findings provide a more fine-grained understanding of the associations between mental disorders and subsequent suicidal behavior than previously available and indicate that mental disorders predict suicidal behaviors similarly in both developed and developing countries. Future research is needed to delineate the mechanisms through which people come to think about suicide and subsequently progress from ideation to attempts. Please see later in the article for Editors'' Summary 相似文献13.
Bo Du Chang‐Jing Liu Meng Yang Shi‐Jie Bao Meng‐Meng Guan Nai‐Fa Liu 《Journal of avian biology》2014,45(5):466-474
Songbirds in seasonal environments often adjust their breeding strategy according to spatial or temporal changes in breeding conditions. Here we investigate how horned larks Eremophila alpestris, a multi‐brooded songbird on the Tibetan Plateau, responded to the changing risk of nest predation and food availability across breeding attempts. We showed that both nest concealment and food supply increased with plant growth, and horned larks adjusted their breeding strategies accordingly. First they selected nest‐sites where predator density was low, which enhanced nest survival. Second, clutch size increased with improving breeding conditions. They did not adopt an ‘egg‐size’ strategy as egg size did not change with laying sequence or breeding attempt. Instead, they adopted the ‘brood survival (feeding later‐hatched nestlings more)’ and ‘brood reduction (feeding early‐hatched nestlings more)’ strategies during early and later attempts. Moreover, nestlings’ growth varied with breeding attempt: more energy was invested into the growth of body mass during the first attempt but more energy was expended on the growth of linear structures during later attempts. This difference in energy allocation reflected changing food availability. We suggest that temporal changes of environmental factors are also the important force driving the evolution of avian breeding strategies. 相似文献
14.
Peripheral blood lymphocytes from 43 patients with Hodgkin's disease were studied for spontaneous growth in longterm cultures in vitro. The rate of culture establishment in Hodgkin's patients was dependant on a positive Epstein-Barr-Virus (EBV)-seroreactivity and intact delayed hypersensitivity reaction to tuberculin. Localized and inactive disease, as well as the absence of atypical mononuclear cells in the peripheral blood had a favourable influence on the longterm in vitro growth. The overall establishment rate in Hodgkin patients was 18 out of 60 attempts (30%), 16 out of 34 (47%) in patients without treatment, only 2 out of 26 (7.7%) attempts during treatment. These results were compared with culture attempts of peripheral blood cells from healthy individuals and umbilical cord blood lymphocytes. Only 12 out of 60 attempts in healthy donors (18.2%) and 0 out of 49 attempts with umbilical cord blood lymphocytes were successful. 相似文献
15.
The effect of kleptoparasite and host numbers on the risk of food‐stealing in an avian assemblage
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Kleptoparasitism involves the theft of resources such as food items from one individual by another. Such food‐stealing behaviour can have important consequences for birds, in terms of individual fitness and population sizes. In order to understand avian host–kleptoparasite interactions, studies are needed which identify the factors which modulate the risk of kleptoparasitism. In temperate European intertidal areas, Eurasian oystercatchers Haematopus ostralegus feed primarily on bivalve molluscs, which may be stolen by kleptoparasitic species such as carrion crows Corvus corone and herring gulls Larus argentatus. In this study we combined overwinter foraging observations of oystercatchers and their kleptoparasites on the Exe Estuary, UK, with statistical modelling to identify the factors that influence the likelihood of successful food stealing behaviour occurring. Across the winter, 16.4% of oystercatcher foraging attempts ended in successful kleptoparasitism; the risk of theft was lowest in February (10.8%) and highest in December (36.3%). Using an information theoretic approach to compare multiple logistic regression models we present evidence that the outcome of host foraging attempts varied with the number of kleptoparasites per host within the foraging patch for two out of five individual months, and for all months grouped. Successful, kleptoparasitism was more likely to occur when the total number of all kleptoparasites per host was greater. Across the entire winter study period, oystercatcher foraging attempts that resulted in kleptoparasitism were associated with a mean number of kleptoparasites per host that was more than double that for foraging attempts that ended in the oystercatcher successfully consuming the mussel. Conversely, the stage of the tidal cycle within the estuary did not affect the outcome of oystercatcher foraging attempts. Our study provides evidence that bird numbers influence the risk of kleptoparasitism within avian assemblages. 相似文献
16.
Differences in the foraging strategies among young individuals of the yellow perch (Perca flavescens) were observed in the laboratory by using two kinds of food (Daphnia and brine shrimp) separately and together. Individuals differed significantly in their ability for feeding attempts, time interval between two consecutive feeding attempts, feeding angles, regurgitation rate, and number of unsuccessful attempts and in their food preference. It is concluded that there are individuals with different foraging strategies. Variability in foraging strategies within single species populations is important because it may explain how the conspecific individuals may differ in their overall feeding behaviour. 相似文献
17.
《Indian pacing and electrophysiology journal》2021,21(5):316-320
Data is scarce regarding epicardial ablation in children. I herewith present a case of successful epicardial ablation in a child with previous unsuccessful attempts at endocardial ablation. This report could be used to guide further such attempts. 相似文献
18.
Zlatskaia AV 《Genetika》2005,41(8):1013-1026
The results of studies on genetic control of the grain protein content character in common wheat and the attempts of its improvement using traditional breeding approaches and methods of experimental mutagenesis and introgressive hybridization are presented. The evolution of the views on the genetic structure of the character is considered. Possible explanations are given to the fact that the attempts to significantly improve the character in question in common wheat cultivars have failed in spite of long-term genetic and selection studies. Possible lines of further investigation of genetic control of grain protein content and its increase in common wheat are discussed. 相似文献
19.
Ann Cloarec 《Ethology : formerly Zeitschrift fur Tierpsychologie》1990,86(1):33-46
At all developmental stages, Diplonychus indicus Venk. & Rao (Heteroptera: Belostomatidae) bugs make predatory attempts and catch prey both from ambush and while foraging actively. The distribution of predatory movements between these two foraging modes does not vary significantly during development, although a bug generally performs more predatory attempts from ambush than during active search. Both modes were subdivided and six different predatory movement types were recorded. These different predatory types are not all performed at the same frequency at all developmental stages. The proportion of predatory attempts including a preliminary lunge decreases with age whereas the proportion of simple predatory attempts (strike) increases with age. There is a significant effect of developmental stage and of predatory mode on capture success. General capture success rate increases with age and success rates vary with predatory type. Capture success of predatory attempts made while swimming is always lower than capture success of simple predatory attempts (strike). These rates do not vary during development. On the contrary, success rates for the predatory types dive and lunge increase with developmental stage. For some predatory categories, capture success varies with predator-prey distance. The data then suggest that the bugs are undershooting. 相似文献
20.
In vitro cultivation of cells from aneuploid human embryos. Initiation of cell lines and longevity of the cultures. 总被引:2,自引:0,他引:2
During a cytogenetic study of human spontaneous abortions, attempts were made to initiate cell lines from tissues of embryos with chromosomal anomalies. The rate of success of these attempts and the life-span of the cell cultures is correlated with the development attained by these aneusomic embryos. 相似文献