Search results for "Reproduction"
showing 10 items of 752 documents
Mating system variation inVeronica(Plantaginaceae): inferences from pollen/ovule ratios and other reproductive traits
2012
The pollen–ovule ratio (P/O) is commonly used to estimate the mode of sexual reproduction in flowering plants. In previous studies, a clear correspondence has been detected between this character and the degree of autogamy. We here investigate variation in this character and its expected correlates in the genus Veronica (Plantaginaceae). Pollen–ovule ratios of 45 species representing eleven percent of all the species in the genus were investigated and compared with results from crossing experiments from previous studies. In addition, multiple populations of 17 of the 45 studied species were sampled and a controlled-environment experiment was conducted to evaluate the extent of intraspecific…
Les nouvelles technologies vont-elles creuser les écarts entre pays riches et pauvres ?
2000
Actes des deuxièmes entretiens internationaux sur l'enseignement à distance, 1er et 2 décembre 1999; International audience; Cette communication s'intéresse aux conséquences de l'introduction des technologies de l'information et de la communication (TIC) dans les systèmes éducatifs à l'échelle mondiale. Elle montre que les écarts entre pays riches et pays pauvres ont tendance à se creuser, tant au point de vue de la richesse économique qu'à celui du développement des systèmes éducatifs. Malgré les spectaculaires réductions des prix des matériels et des logiciels, les capacités des pays dits les moins avancés à s'approprier les TIC dans les processus d'apprentissage sont très compromises en …
Mother and offspring fitness in an insect with maternal care: phenotypic trade-offs between egg number, egg mass and egg care
2014
Background Oviparous females have three main options to increase their reproductive success: investing into egg number, egg mass and/or egg care. Although allocating resources to either of these three components is known to shape offspring number and size, potential trade-offs among them may have key impacts on maternal and offspring fitness. Here, we tested the occurrence of phenotypic trade-offs between egg number, egg mass and maternal expenditure on egg care in the European earwig, Forficula auricularia, an insect with pre- and post-hatching forms of maternal care. In particular, we used a series of laboratory observations and experiments to investigate whether these three components no…
Ocean acidification affects fish spawning but not paternity at CO2 seeps
2016
Fish exhibit impaired sensory function and altered behaviour at levels of ocean acidification expected to occur owing to anthropogenic carbon dioxide emissions during this century. We provide the first evidence of the effects of ocean acidification on reproductive behaviour of fish in the wild. Satellite and sneaker male ocellated wrasse (Symphodus ocellatus) compete to fertilize eggs guarded by dominant nesting males. Key mating behaviours such as dominant male courtship and nest defence did not differ between sites with ambient versus elevated CO2 concentrations. Dominant males did, however, experience significantly lower rates of pair spawning at elevated CO2 levels. Despite the higher r…
Sublethal zinc exposure has a detrimental effect on reproductive performance but not on the cyst hatching success of Artemia parthenogenetica
2008
The sublethal zinc toxicity to Artemia parthenogenetica as regards the possibility of colonization of zinc polluted salterns by means of cysts has been assessed by a cyst hatching assay and a life table approach. Emergence and hatching at different times as well as the whole hatching profile were taken as end-points for evaluating success of development. Demographic and reproductive parameters calculated according to the Lotka equation were used as an indicator of the chronic toxicity of the population. No adverse effects of waterborne zinc were found on hatching and emergence of cysts of A. parthenogenetica at any of the concentrations tested (0.01 mg/l, 0.1 mg/l, 0.5 mg/l, 1 mg/l, 5 mg/l)…
Robot Shift from Industrial Production to Social Reproduction
2015
This chapter analyses people’s attitudes towards the use of robots in the different domains of life and, specifically, in the domain of social reproduction. The analysis is based on Eurobarometer 382 “Public Attitudes towards Robots” data (N = 26,751), which was carried out among EU citizens aged 15 and over in 27 member states in 2012. The results of the study show that on average European perceptions of robots are positive and permissive. The life domains in which robots have already been used for a long time (e.g. space exploration, manufacturing, military and security business, search and rescue work) turn out to be the most popular areas for the further penetration of robots. The least…
The Principle of Respect for Human Vulnerability and Assisted Reproductive Technologies
2016
The chapter tackles the assisted reproductive technologies (ARTs), and the incorporation of two controversial procedures to increase the number of individuals who may satisfy their wish to have children: international commercial surrogacy and mitochondrial transfer. Both of them have an important point in common: the high degree of involvement within the reproduction process demanded to a different woman from the woman who will be the legal mother. In international surrogacy, a woman undergoes a baby gestation for another woman in a different country, who will be the legal mother since the baby is born. In mitochondrial transfer, a woman donates her eggs so that her mitochondria may be used…
A model of goal dynamics in technology-based organizations
2011
The purpose of the present work is to build a suitable system dynamics model for goal dynamics in organizations, as proposed by Barlas and Yasarcan (2008). The proposed model does not bear any ambition of being exhaustive: the main objective of this paper is to propose a model of goal dynamics in which Goal Setting, Management by Objectives and Training are viewed as human resource practices able to enhance workers' goal commitment, and therefore, improve organizational performance. In the first part of this paper, an analysis of the Goal Setting Theory and the role of goal setting practices, in bettering worker's performance, are stressed. In the second part, a case-study, the causal loop …
Evaluation of the effects of titanium dioxide and aluminum oxide nanoparticles through tarsal contact exposure in the model insect Oncopeltus fasciat…
2019
Abstract Despite the increasing presence of metal nanoparticles in the biosphere as a consequence of their widespread use, knowledge about the impact of these nanoparticles on fauna, ecosystems and human health is far from completion. This is especially true for terrestrial invertebrates. Insects are environmentally exposed to nanoparticles by several ways, the ectopic contact being one of the most probable. The model insect Oncopeltus fasciatus, has been used in the present work for testing toxicity of nanoparticles present in a surface. Adverse effects of TiO2 nanoparticles and Al2O3 in nanoparticulated or bulk form on mortality, reproductive and embryonic developmental parameters have be…
Effect of the lipid regulator Gemfibrozil in the Cladocera Daphnia magna at different temperatures.
2016
ABSTRACTIn the present study, an ecotoxicological approach to the evaluation of Gemfibrozil (GEM) as an emerging organic pollutant was done. In order to assess its toxicity, tests were conducted using the cladocera Daphnia magna. Experiments were carried out at 22°C and 28°C. EC50, feeding behavior, and chronic toxicity tests (21 days) were evaluated in D. magna exposed to GEM as well as cholesterol levels at 21-day chronic exposure. D. magna GEM EC50 values (24 h) in our experimental conditions were 148.75 and 116.24 mg L−1 at 22°C and 28°C, respectively. Test concentrations of 0.1, 0.5, 1.0, 5.0 and 7.5 mg L−1 were selected for subacute and chronic experiments. Subacute short-term test (f…