Search results for "General Agricultural and Biological Sciences"
showing 10 items of 1320 documents
AN ANALYSIS OF CONTINENT-WIDE PATTERNS OF SEXUAL SELECTION IN A PASSERINE BIRD
2006
Patterns of selection are widely believed to differ geographically, causing adaptation to local environmental conditions. However, few studies have investigated patterns of phenotypic selection across large spatial scales. We quantified the intensity of selection on morphology in a monogamous passerine bird, the barn swallow Hirundo rustica, using 6495 adults from 22 populations distributed across Europe and North Africa. According to the classical Darwin-Fisher mechanism of sexual selection in monogamous species, two important components of fitness due to sexual selection are the advantages that the most attractive males acquire by starting to breed early and their high annual fecundity. W…
New insights into the diversity dynamics of Triassic conodonts
2013
International audience; In this paper, we examine the diversity trends and the evolutionary patterns of Triassic conodonts through a newly powered large-scale data-set compiled directly from the primary literature. Paleodiversity dynamics analyses have been undertaken by working at the species level and using a system of time units based on biozone subdivisions for a fine temporal level resolution. The role of heterogeneous duration of taxa in diversity estimates has been evaluated through the probabilistic profiles. Results reveal three different stages in the diversity behaviour of Triassic conodonts from standing metrics delimited by two inflections at the mid-Anisian and mid-Carnian. Su…
THERMOREGULATION CONSTRAINS EFFECTIVE WARNING SIGNAL EXPRESSION
2009
Evolution of conspicuous signals may be constrained if animal coloration has nonsignaling as well as signaling functions. In aposematic wood tiger moth (Parasemia plantaginis) larvae, the size of a warning signal (orange patch on black body) varies phenotypically and genetically. Although a large warning signal is favored as an antipredator defense, we hypothesized that thermoregulation may constrain the signal size in colder habitats. To test this hypothesis, we conducted a factorial rearing experiment with two selection lines for larval coloration (small and large signal) and with two temperature manipulations (high and low temperature environment). Temperature constrained the size and br…
Regeneration in invertebrates
2008
The mechanisms of regeneration are reviewed from a genetic, cytological and molecular biological points of view. Planarians and Hydra have been chosen and illustrated as biological examples.
Phenolic compounds in different olive varieties
2001
Phenolic compounds in different olive varieties were determined by HPLC analysis over 2 years. Demethyloleuropein was found in only two (Coratina and Leccino) of the eight varieties studied, so it could be used as varietal marker. Elenolic acid glucoside and hydroxytyrosol can be considered indicators of maturation for olives. In fact, as the olives ripen, their tenor increases whereas oleuropein decreases. Keywords: Phenolic compounds; olive fruit; oleuropein; demethyloleuropein; 3,4-dihydroxyphenylethanol; elenolic acid glucoside
Distribution of biomass and site location of combustion and gasification power plants in western Sicily
2012
The substitution of conventional fossil fuels with biomass for energy production results both in the reduction of greenhouse gases emissions and in the replacement of non-renewable energy sources. The use of biomass for energy production responds to the growing pressure of government policies towards the achievement of better environmental sustainability of power generation processes. This is particularly true for the agricultural areas of Sicily, where the realization of new economic dynamics can lead to development of a local economic system. However, at present, generating energy from biomass is rather expensive due to both technological limits related to low conversion efficiencies, and…
Comparison between two different cardiovascular models during a hemorrhagic shock scenario
2020
Hemorrhagic shock is a form of hypovolemic shock determined by rapid and large loss of intravascular blood volume and represents the first cause of death in the world, whether on the battlefield or in civilian traumatology. For this, the ability to prevent hemorrhagic shock remains one of the greatest challenges in the medical and engineering fields. The use of mathematical models of the cardiocirculatory system has improved the capacity, on one hand, to predict the risk of hemorrhagic shock and, on the other, to determine efficient treatment strategies. In this paper, a comparison between two mathematical models that simulate several hemorrhagic scenarios is presented. The models considere…
Sexually selected traits evolve positive allometry when some matings occur irrespective of the trait
2014
Positive allometry of secondary sexual traits (whereby larger individuals have disproportionally larger traits than smaller individuals) has been called one of the most pervasive and poorly understood regularities in the study of animal form and function. Its widespread occurrence is in contrast with theoretical predictions that it should evolve only under rather special circumstances. Using a combination of mathematical modeling and simulations, here we show that positive allometry is predicted to evolve under much broader conditions than previously recognized. This result hinges on the assumption that mating success is not necessarily zero for males with the lowest trait values: for examp…
Fear of COVID-19, Risk Perception and Stress Level in Polish Nurses During COVID-19 Outbreak
2021
Introduction. The outbreak of COVID-19 disease causes severe stress in health care workers, especially nurses.Nurses are at high risk of contracting the disease, as well as an increased risk of developing mental health symptomssuch as fear, anxiety and work-related stress.Aim. The aim of the study was to determine the relationship between fear of COVID-19, risk perception, perceivedthreat and stress in Polish nurses during COVID-19 outbreak.Material and Methods. 106 nurses participated in the study. Perceived Stress Scale (PSS-10), Fear of COVID-19 Scale(FOC-6), Risk of Contracting COVID-19 Scale and Perceived Threat of COVID-19 Scale were used in the study.Results. It has been shown that p…
Ability of the ISAS3Fun Method to Detect Sperm Acrosome Integrity and Its Potential to Discriminate between High and Low Field Fertility Bulls
2021
The objective of the present study was to investigate whether fertility differences in bulls are reflected in variations of sperm quality when analysing only one ejaculate per male. Two experiments were performed. In the first experiment, frozen semen samples from 20 adult bulls were tested