background: previous studies indicate a high incidence of digestive cancers along southern parts of caspian sea including ma­zandaran province. the present study was conducted to further investigate time to occurrence, age distribution and pos­sible risks associated with the incidence time of digestive cancers in the above regions. methods: for this purpose the data of digestive cancer incidenc...

spodoptera exigua (hübner) was studied in laboratory (25±1ºc, 60±5% rh, and 16:8 l:d h) exploring the antibiotic effects of 10 canola cultivars (sarigol, slm046, hayula420, rgs003, opera, okapi, licord, modena, zarfam and talaye) on its demographic parameters. the age-stage, two-sex and the traditional female age-specific life tables were constructed by using the demographic data. the larval pe...

increased nitrogen applications to crops influence plant-herbivore interactions and potentially increase herbivore population growth.in this research, the impact of nitrogen fertilizations on nutritional quality of three canola (brassica napus l.) cultivars (zarfam, okapi and modena), and, consequently, the performance of mustard aphids, lipaphis erysimi kalt., on them were investigated under g...

Postponement has been a major keyword in the description and the study of demographic trends observed in developed countries during the last decades. With few exceptions, during the recent decades demographic events such as those leading to the formation of new households and families have occurred later and later in the lives of women and men. Although considerable heterogeneity exists both be...

Data from the 1985 Spanish Survey of Fertility including 8789 women aged 18-49 years is used to examine the timing of 1st births from marriage. Premarital births are excluded. Life table estimates are used to describe trends and differentials. A piecewise constant hazard model, which assumes a constant transition rate within each duration segment (0-7, 8-12, 13-18, 19-24, 25-36, and 37-48 mo...

The Standard Days Method is a fertility awareness-based method of family planning in which users avoid unprotected intercourse during cycle Days 8 through 19. A prospective multi-center efficacy trial was conducted to test, in a heterogeneous population, the contraceptive efficacy of the Standard Days Method. A total of 478 women, age 18–39 years, in Bolivia, Peru, and the Philippines, with sel...

Comparative studies of gyrodactylid monogeneans on different host species or strains rely upon the observation of growth on individual fish maintained within a common environment, summarised using maximum likelihood statistical approaches. Here we describe an agent-based model of gyrodactylid population growth, which we use to evaluate errors due to stochastic reproductive variation in such exp...

OBJECTIVE To evaluate the resistance of Aedes aegypti to temephos Fersol 1G (temephos 1% w/w) associated with the adaptive disadvantage of insect populations in the absence of selection pressure. METHODS A diagnostic dose of 0.28 mg a.i./L and doses between 0.28 mg a.i./L and 1.40 mg a.i./L were used. Vector populations collected between 2007 and 2008 in the city of Campina Grande, state of P...

reducing nitrogen status of floriculture plants is an effective tactic in pest management by decreasing host plant quality. life table parameters and population growth rate of aphis craccivora(hemiptera: aphidiae), as well as cosmetic and qualitative parameters losses associated with aphid infestation were evaluated in relation to n fertilization levels on gomphrena globosa, under greenhouse co...

Lotkai proved that the age distribution of any population that is subject, for a sufficiently long time, to constant fertility and mortality becomes fixed. He called this end-product of constant demographic conditions a "stable population", characterized both by an unchanging age distribution and by a fixed annual rate of natural increase. The age distribution of a stable population is jointly ...