a total of twenty local and foreign maize (zea mays l.) hybrids in five different maturity group were studied in mashhad for two years (2007-2008). temperature variations were created by two planting dates (5 may and 20 may). results indicated that both indices, gdd and chu, estimated heat units of different maturity hybrids and based on, created similar groups of hybrids. both indices showed s...

The reproductive strategies of the sea urchin, Paracentrotus lividus, was studied in the Bay of Tunis. Samples were collected monthly, from September 1993 to August 1995, in two sites which differ in their marine vegetation and their exposure to wave action. Histological examination demonstrated a cycle of gametogenesis with six reproductive stages and a main breeding period occurring between A...

In this paper, we develop the theory of a state-reproduction number for a multistate class age structured epidemic system and apply it to examine the asymptomatic transmission model. We formulate a renewal integral equation system to describe the invasion of infectious diseases into a multistate class age structured host population. We define the state-reproduction number for a class age struct...

The reproductive strategies of the sea urchin, Paracentrotus lividus, was studied in the Bay of Tunis. Samples were collected monthly, from September 1993 to August 1995, in two sites which differ in their marine vegetation and their exposure to wave action. Histological examination demonstrated a cycle of gametogenesis with six reproductive stages and a main breeding period occurring between A...

In this study production, reproduction, population, management and economic parameters resulted from recording of 7 flocks with size 57 to 400 and 721 heads of camels in a cycle of reproduction, during three years from 2011 to 2013 were used to find out of the economic values of important traits in one hump camel in desert areas rearing system. The economic traits that appeared in profit equati...

Condition indices are commonly used in an attempt to link body condition of birds to ecological variables of interest, including demographic attributes such as survival and reproduction. Most indices are based on body mass adjusted for structural body size, calculated as simple ratios or residuals from regressions. However, condition indices are often applied without confirming their predictive...