نتایج جستجو برای: type population dynamics

تعداد نتایج: 2324559  

2015
Sergey V. Ershkov

A key points of new approach for modeling of the population dynamics in reactive environment are presented here: 1) generalization of the Logistic equation to the case of reactive environment for modeling of population dynamics (or for the fulfilling of the ecological niches); 2) new type of asymptotic solution for such equation (which is tested on human population growth); 3) reduction to the ...

Journal: :The American naturalist 2007
Ido Filin Ofer Ovadia

Much recent literature is concerned with how variation among individuals (e.g., variability in their traits and fates) translates into higher-level (i.e., population and community) dynamics. Although several theoretical frameworks have been devised to deal with the effects of individual variation on population dynamics, there are very few reports of empirically based estimates of the sign and m...

2017
Kim M Pepin Amy J Davis Fred L Cunningham Kurt C VerCauteren Doug C Eckery

Effective management of widespread invasive species such as wild pigs (Sus scrofa) is limited by resources available to devote to the effort. Better insight of the effectiveness of different management strategies on population dynamics is important for guiding decisions of resource allocation over space and time. Using a dynamic population model, we quantified effects of culling intensities and...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه پیام نور - دانشگاه پیام نور استان تهران - پژوهشکده علوم انسانی و اجتماعی 1390

چکیده: هدف: هدف از پژوهش حاضر مقایسه حافظه (کوتاه مدت، بلند مدت و بصری) در بیماران مبتلا به دیابت نوع 2 و افراد سالم می باشد. روش: روش پژوهش از نوع علی مقایسه ای است. جامعه آماری این تحقیق را کلیه بیماران مبتلا به دیابت نوع 2 ساکن شهرستان پارس آباد و روستاهای اطراف آن تشکیل می دهند. از بین این جامعه، 40 نفر از بیماران مراجعه کننده به پزشکان متخصصین داخلی و پزشکان خانواده که در شهرستان پارس آبا...

2012
Yun Kang Carlos Castillo-Chavez Simon Levin

In this article, we study population dynamics of a simple two-patch SI model with three features: i) strong Allee effects built in the net reproduction rates; ii) the disease-modified fitness such as the reproduction ability and the competitive ability in different population levels; and iii) dispersal whose rate is proportional to the difference of population between two patches. We derive suf...

2005
Steven E. Naranjo Peter C. Ellsworth

Natural mortality is an important determinant of the population dynamics of a species, and an understanding of mortality forces should aid in the development of better management strategies for insect pests. An in situ, observational method was used to construct cohort-based life tables for Bemisia tabaci (Gennadius) Biotype B (Homoptera: Aleyrodidae) over 14 generations on cotton in central Ar...

2014
EVAN G. COOCH MATTHIEU GUILLEMAIN G. SCOTT BOOMER JAMES D. NICHOLS

Change in the size of populations over space and time is, arguably, the motivation for much of pure and applied ecological research. The fundamental model for the dynamics of any population is straightforward: the net change in the abundance is the simple difference between the number of individuals entering the population and the number leaving the population, either or both of which may chang...

Journal: :The American naturalist 2003
Megan J Donahue Marcel Holyoak Charles Feng

Both source-sink theory and extensions of optimal foraging theory ("balanced dispersal" theory) address dispersal and population dynamics in landscapes where habitat patches vary in quality. However, studying dispersal mechanisms empirically has proven difficult, and dispersal is rarely tied back to long-term spatial dynamics. We used a manipulable laboratory system consisting of bacteria and p...

Journal: :journal of agricultural science and technology 2010
h. saremi l. w. burgess

environmental factors mainly temperature are believed to determine the distribution and population dynamics of fusarium species in a natural ecosystem. species may be restricted in their distribution by adaptation to specific sets of soil environmental conditions. population dynamics of five fusarium species representative of different climatic conditions were studied at three levels of tem...

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