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1.
Summary An increase in fish mortality due to fishing can theoretically change the growth and reproduction of fish populations from
the viewpoint of adaptation. We address the issue of how an iteroparous fish should convert surplus energy into somatic growth
and reproduction at each age under given conditions of mortality. A model of life history, which maximizes the net reproductive
rate using the discrete maximum principle, is improved employing a new relationship between body weight and surplus energy
which we have recently proposed. The model is applied to the North Sea plaicePleuronectes platessa, for which it has been reported that the average length of young fish had increased whereas that of old ones had decreased
for some decades. Although the model cannot directly explain the former phenomenon, the two phenomena can be interpreted as
a change in the optimal life history due mainly to an increase in mortality. 相似文献
2.
Megumi Inoue Jennifer Entwistle Michael Wolf-Branigin Karen Wolf-Branigin 《Journal of social work practice in the addictions》2017,17(3):275-290
Fetal alcohol spectrum disorder (FASD) is the leading preventable intellectual and developmental disability. There is no safe level of alcohol consumption at any point during pregnancy. Findings of this study indicate that the information disseminated by health care professionals is not always in keeping with this understanding. Physicians and midwives appeared to be the least consistent in advocating to women that they abstain from alcohol consumption while pregnant. We explore ways in which social workers can support the medical profession to provide more consistent messaging of alcohol abstinence during pregnancy to lower the incidence of FASD. 相似文献
3.
Consider a random variable S being the sum of a number N of independent and identically distributed random variables Xj (j = 1, 2, ...) where the number N is itself a non-negative integer-valued random variable independent of the Xj An explicit expression of the r-th cumulant of S is given in terms of the cumulants of N and Xj, Asymptotic properties of the distribution of S are also discussed. 相似文献
4.
5.
Recently, along with the enhancement of the argument for career of athletes, many researchers who major in sports psychology focus mainly on athletic retirement, a coordination of transitions in sport or and outside sport, social support and professional assistance in career transition, in the context of the second career concerning to professional athletes in Japan. However, when it comes to career transition of professional athletes, it is necessary to consider "career" from the whole perspectives of human life. Therefore, the purpose of this study is to clarify the career transition of professional athletes by the way of questionnaire and interview survey, which is approached from the view point of industrial/organizational psychology. For this purpose, we implemented the interview survey to professional athletes in 2008. In addition, we carried out the investigation to professional football players (interview survey: 5 players, questionnaire survey: 102 players) in 2009. Consequently, three following findings were led in conclusion. (1)Career intervention to professional athletes should be performed before the turning point of the career (career transition). (2)It is important to assess the career intervention to professional athletes. (3)It is an important stance to watch the processes when professional athletes open up one's career by oneself. 相似文献
6.
一、引言日本的司法制度改革是20世纪80年代以后,总括《有关司法制度应有状态的讨论》的形式进行的,是一种包括性、综合性的改革。改革的对象范围几乎涉及到司法制度的所有层面:不仅包括司法制度本身的改革,还包括法曹培养系统的改革(法科大学院、新的司法考试制度)和 相似文献
7.
This article proposes new methodologies for evaluating economic models’ out-of-sample forecasting performance that are robust to the choice of the estimation window size. The methodologies involve evaluating the predictive ability of forecasting models over a wide range of window sizes. The study shows that the tests proposed in the literature may lack the power to detect predictive ability and might be subject to data snooping across different window sizes if used repeatedly. An empirical application shows the usefulness of the methodologies for evaluating exchange rate models’ forecasting ability. 相似文献
8.
It is widely known that significant in-sample evidence of predictability does not guarantee significant out-of-sample predictability. This is often interpreted as an indication that in-sample evidence is likely to be spurious and should be discounted. In this paper, we question this interpretation. Our analysis shows that neither data mining nor dynamic misspecification of the model under the null nor unmodelled structural change under the null are plausible explanations of the observed tendency of in-sample tests to reject the no-predictability null more often than out-of-sample tests. We provide an alternative explanation based on the higher power of in-sample tests of predictability in many situations. We conclude that results of in-sample tests of predictability will typically be more credible than results of out-of-sample tests. 相似文献
9.
Summary As a quantitative approach to the life histories of fishes, the present paper attempted to predict a relation among reproduction,
growth and mortality numerically with a technique of control theory, the discrete maximum principle. A method for predicting
the relation was derived on the postulate that natural selection maximized the net reproductive rate subject to a few constraints.
The derived method was applied to Atlantic cod and Atlantic herring populations in the Southern Gulf of St. Lawrence as numerical
examples. The examples demonstrated that the theoretical reproductive effort and body weight were well consistent with the
observed ones every age but the theoretical survival rates were slightly different from the observed ones. For the reasons
mentioned below, however, it should be interpreted that the examples rather support the adopted postulate to a certain degree.
First, in general, it is very difficult to obtain good estimates of the rates with traditional methods. Second, intense fishing
pressure possibly changes the life history parameters to some extent in fish populations. Moreover, the examples also suggested
that, to examine the postulate in further detail, similar analyses had to be made with the data of many fish populations on
which intense fishing pressure had not been exerted. 相似文献
10.