Comments on the Use of Time-Specific and Cohort Life Tables

Ecology ◽  
1993 ◽  
Vol 74 (7) ◽  
pp. 2164-2168 ◽  
Author(s):  
George E. Menkens ◽  
Mark S. Boyce
Keyword(s):  
Life Tables ◽  
Use Of Time ◽  
Time Specific

Time-Specific Life Tables for Acyrthosiphon kondoi (Homoptera: Aphididae) in First Crop Alfalfa in Oklahoma

1990 ◽  
Vol 19 (4) ◽  
pp. 1001-1009 ◽  
Author(s):  
M. Ashraf Poswal ◽  
R. C. Berberet ◽  
L. J. Young
Keyword(s):  
Life Tables ◽  
Time Specific

Age-Grouping, Time-Specific Life-Tables, and Predictive Population Models

2021 ◽  
pp. 362-383
Author(s):  
Peter A. Henderson
Keyword(s):  
Developmental Stage ◽  
Food Availability ◽  
Life Tables ◽  
Population Models ◽  
Leslie Matrix ◽  
Population Modelling ◽  
Temperature Dependent ◽  
Animal Groups ◽  
Leslie Matrices ◽  
Time Specific

This chapter describes techniques to create life-tables for animals whose generations overlap widely. Age-grouping is a prerequisite for these methods, which have been most widely applied to vertebrate populations. Age cannot be inferred from the developmental stage without reference to the environment. The speed of development may be temperature-dependent or influenced by factors such as oxygen and food availability. The methods for ageing animal groups, including invertebrates, fish, reptiles, amphibians, birds, and mammals, are reviewed. Time-specific life-tables, population modelling, and Leslie matrices are described. R code to analyze Leslie matrix dynamics is presented.

A comparison of time-specific and cohort-specific life tables for Belding's ground squirrels, Spermophilus beldingi

1986 ◽  
Vol 64 (3) ◽  
pp. 602-605 ◽  
Author(s):  
Richard M. Zammuto ◽  
Paul W. Sherman
Keyword(s):  
Life Table ◽  
Survival Data ◽  
Life Tables ◽  
Ground Squirrels ◽  
Age Classes ◽  
Free Living ◽  
Female Population ◽  
Spermophilus Beldingi ◽  
Time Specific ◽  
Combined Data

Eight years of age-specific survival data and 6 years of fecundity data from a free-living population of Belding's ground squirrels (Spermophilus beldingi) at Tioga Pass, California, were used to test the hypothesis that time-specific life tables, based on data from individual years, were different from the cohort-specific life table, based on the combined data from all years. The results indicated that neither the age structure of the male nor the female population significantly differed among years (all P > 0.05). Furthermore, the means and the variances in the sizes of weaned litters did not differ among years either in the population at large or within individual age-classes (all P > 0.05). A 27-day snowstorm that occurred in the spring of 1977 increased mortality and reduced reproduction, but it did not change the ground squirrels' age-specific survival or fecundity patterns. Taken together, our analyses revealed that each time-specific life table provided age-specific survival and fecundity estimates that were statistically indistinguishable (P > 0.05) from the composite, cohort-specific life table for each sex, regardless of severe environmental conditions. This is the first demonstration of the equivalence of time- and cohort-specific life tables for a free-living population of mammals.

Time-Specific and Cohort Life Tables for Belding's Ground Squirrels

Ecology ◽  
1993 ◽  
Vol 74 (7) ◽  
pp. 2168-2169
Author(s):  
Paul W. Sherman ◽  
Richard M. Zammuto
Keyword(s):  
Life Tables ◽  
Ground Squirrels ◽  
Time Specific

Time-Specific Life Tables Contrasted with Observed Survivorship

Biometrics ◽  
1947 ◽  
Vol 3 (3) ◽  
pp. 129 ◽  
Author(s):  
Margaret Merrell
Keyword(s):  
Life Tables ◽  
Time Specific

Simulated safety performance of rear-end and angled vehicle interactions at isolated intersections

2009 ◽  
Vol 36 (11) ◽  
pp. 1794-1803 ◽  
Author(s):  
Flávio Cunto ◽  
Frank F. Saccomanno
Keyword(s):  
Simulation Model ◽  
Performance Measures ◽  
Safety Performance ◽  
Microscopic Simulation ◽  
Use Of Time ◽  
Intersection Safety ◽  
Potential Index ◽  
Time Specific ◽  
Isolated Intersection

This paper applies a calibrated microscopic simulation model to assess the safety implications of signalization at a stop-controlled isolated intersection. Safety performance is measured in terms of a crash potential index (CPI) that makes use of time-specific vehicle parameters, such as deceleration rates, spacing, and speed profiles. Four performance measures are obtained: (i) average CPI/vehicle, (ii) CPI 85th percentile, (iii) number of vehicles with CPI > 0 (defined as interacting), and (iv) number of conflicts (defined in terms of a given CPI threshold). Two types of interactions are considered, namely rear end and angled. For rear-end interactions, CPI/vehicle was found to be significantly higher following the introduction of fixed signal controls. For angled interactions, CPI/vehicle was found to decrease with signalization. For both types of interactions, the CPI 85th percentile was found to decrease nonlinearly with signalization, especially for higher assumed volumes on the major approach. Rear-end vehicle interactions increased significantly following signalization and with increasing volume, whereas no such increase was observed for angled interactions. The key observation is that the number of vehicles subject to angled interactions was found to decrease after signalization.

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