998 resultados para mating time
Resumo:
Mothers' general anxiety, anxiety about the well-being of the child and psychological stress before prenatal testing was studied by comparing women who conceived through in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) with women who conceived naturally. Before the first trimester screening test for Down's syndrome, a group of 51 women who conceived through IVF/ICSI and a group of 54 women who conceived spontaneously completed the State Scale of the State-Trait Anxiety Inventory (S-Anxiety; Spielberger, 1983), the Fear of Bearing a Physically or Mentally Handicapped Child Subscale of the Pregnancy-related Anxiety Questionnaire (PRAQ-R; Huizink et al., 2004), the Psychological Stress Measure (PSM; Lemyre & Tessier, 1988), and the Prenatal Psychosocial Profile (PPP; Curry, Campbell, & Christian, 1994). Women who conceived through IVF/ICSI had more elevated levels of general anxiety and psychological stress than the women who conceived naturally; however, no difference was observed between the two groups for anxiety specifically related to the health of the child. These results underline the need to monitor women's emotional state after conception via IVF/ICSI-when counseling usually ends-and around the time of the first trimester screening. Counseling might thus be extended.
Resumo:
We present the derivation of the continuous-time equations governing the limit dynamics of discrete-time reaction-diffusion processes defined on heterogeneous metapopulations. We show that, when a rigorous time limit is performed, the lack of an epidemic threshold in the spread of infections is not limited to metapopulations with a scale-free architecture, as it has been predicted from dynamical equations in which reaction and diffusion occur sequentially in time
Time of injection determines the effect of alpha-MSH antiserum on DA neurons in psychological stress
Resumo:
Male rats were subjected to "psychological stress" which consisted in 10 sec footshock on the first day followed 24 hr later by a 10 sec stay in the experimental chamber without shock. Intravenous antiserum against alpha-MSH markedly changed the functional state of mesencephalic and hypothalamic DA neurons (assessed by histochemical microfluorimetry) when administered before the second session but not when given before the first session. These observations reveal an interesting parallelism in the temporal characteristics of the effects of alpha-MSH on avoidance behavior and central DA systems.
Resumo:
The photodynamic effects of m-tetrahydroxyphenylchlorin (mTHPC) were assessed on human malignant mesothelioma, squamous cell carcinoma and adenocarcinoma xenografts grown in nude mice and were correlated with mTHPC uptake, histology and doubling time of the tumors. Non-thermal laser light was delivered to the tumor as surface radiation 4 days after intraperitoneal administration of 0.1 and 0.3 mg mTHPC/kg body weight, respectively. The extent of tumor necrosis was measured by histomorphometry. The mTHPC concentration in non-irradiated tumors was assessed by high-performance liquid chromatography (HPLC). The tumors were graded according to their doubling time and their vascular architecture as assessed by histology. The 0.1 mg/kg dose of mTHPC resulted in an equal uptake for all 3 tumor types but revealed a larger extent of photosensitized necrosis for adenocarcinoma, which displayed a delicate tumor stroma with numerous small capillary vessels, than for mesothelioma and squamous cell carcinoma, which were both poor in stroma and vessels. The 0.3 mg/kg dose of mTHPC resulted in a 2-fold higher tumor uptake for all 3 tumor types and in a larger extent of necrosis for mesothelioma and squamous cell carcinoma, but not for adenocarcinoma xenografts, compared with the lower drug dose. Our results demonstrate that different tumor xenografts respond differently to mTHPC-PDT for a given drug-light condition. In this setting, the photosensitizing effect was more closely related to the vascular architecture of the tumors than to the sensitizer uptake and doubling time of the different tumors
Resumo:
Habitat restoration measures may result in artificially high breeding density, for instance when nest-boxes saturate the environment, which can negatively impact species' demography. Potential risks include changes in mating and reproductive behaviour such as increased extra-pair paternity, conspecific brood parasitism, and polygyny. Under particular cicumstances, these mechanisms may disrupt reproduction, with populations dragged into an extinction vortex. With the use of nuclear microsatellite markers, we investigated the occurrence of these potentially negative effects in a recovered population of a rare secondary cavity-nesting farmland bird of Central Europe, the hoopoe (Upupa epops). High intensity farming in the study area has resulted in a total eradication of cavity trees, depriving hoopoes from breeding sites. An intensive nest-box campaign rectified this problem, resulting in a spectacular population recovery within a few years only. There was some concern, however, that the new, high artificially-induced breeding density might alter hoopoe mating and reproductive behaviour. As the species underwent a serious demographic bottleneck in the 1970-1990s, we also used the microsatellite markers to reconstitute the demo-genetic history of the population, looking in particular for signs of genetic erosion. We found i) a low occurrence of extra-pair paternity, polygyny and conspecific brood parasitism, ii) a high level of neutral genetic diversity (mean number of alleles and expected heterozygosity per locus: 13.8 and 83%, respectively) and, iii) evidence for genetic connectivity through recent immigration of individuals from well differentiated populations. The recent increase in breeding density did thus not induce so far any noticeable detrimental changes in mating and reproductive behaviour. The demographic bottleneck undergone by the population in the 1970s-1990s was furthermore not accompanied by any significant drop in neutral genetic diversity. Finally, genetic data converged with a concomitant demographic study to evidence that immigration strongly contributed to local population recovery.
Resumo:
A time-delayed second-order approximation for the front speed in reaction-dispersion systems was obtained by Fort and Méndez [Phys. Rev. Lett. 82, 867 (1999)]. Here we show that taking proper care of the effect of the time delay on the reactive process yields a different evolution equation and, therefore, an alternate equation for the front speed. We apply the new equation to the Neolithic transition. For this application the new equation yields speeds about 10% slower than the previous one
Resumo:
CONTEXT: Sparse data exist on the combined associations between physical activity and sedentary time with cardiometabolic risk factors in healthy children. OBJECTIVE: To examine the independent and combined associations between objectively measured time in moderate- to vigorous-intensity physical activity (MVPA) and sedentary time with cardiometabolic risk factors. DESIGN, SETTING, AND PARTICIPANTS: Pooled data from 14 studies between 1998 and 2009 comprising 20 871 children (aged 4-18 years) from the International Children's Accelerometry Database. Time spent in MVPA and sedentary time were measured using accelerometry after reanalyzing raw data. The independent associations between time in MVPA and sedentary time, with outcomes, were examined using meta-analysis. Participants were stratified by tertiles of MVPA and sedentary time. MAIN OUTCOME MEASURES: Waist circumference, systolic blood pressure, fasting triglycerides, high-density lipoprotein cholesterol, and insulin. RESULTS: Times (mean [SD] min/d) accumulated by children in MVPA and being sedentary were 30 (21) and 354 (96), respectively. Time in MVPA was significantly associated with all cardiometabolic outcomes independent of sex, age, monitor wear time, time spent sedentary, and waist circumference (when not the outcome). Sedentary time was not associated with any outcome independent of time in MVPA. In the combined analyses, higher levels of MVPA were associated with better cardiometabolic risk factors across tertiles of sedentary time. The differences in outcomes between higher and lower MVPA were greater with lower sedentary time. Mean differences in waist circumference between the bottom and top tertiles of MVPA were 5.6 cm (95% CI, 4.8-6.4 cm) for high sedentary time and 3.6 cm (95% CI, 2.8-4.3 cm) for low sedentary time. Mean differences in systolic blood pressure for high and low sedentary time were 0.7 mm Hg (95% CI, -0.07 to 1.6) and 2.5 mm Hg (95% CI, 1.7-3.3), and for high-density lipoprotein cholesterol, differences were -2.6 mg/dL (95% CI, -1.4 to -3.9) and -4.5 mg/dL (95% CI, -3.3 to -5.6), respectively. Geometric mean differences for insulin and triglycerides showed similar variation. Those in the top tertile of MVPA accumulated more than 35 minutes per day in this intensity level compared with fewer than 18 minutes per day for those in the bottom tertile. In prospective analyses (N = 6413 at 2.1 years' follow-up), MVPA and sedentary time were not associated with waist circumference at follow-up, but a higher waist circumference at baseline was associated with higher amounts of sedentary time at follow-up. CONCLUSION: Higher MVPA time by children and adolescents was associated with better cardiometabolic risk factors regardless of the amount of sedentary time.
Resumo:
The classical wave-of-advance model of the neolithic transition (i.e., the shift from hunter-gatherer to agricultural economies) is based on Fisher's reaction-diffusion equation. Here we present an extension of Einstein's approach to Fickian diffusion, incorporating reaction terms. On this basis we show that second-order terms in the reaction-diffusion equation, which have been neglected up to now, are not in fact negligible but can lead to important corrections. The resulting time-delayed model agrees quite well with observations
Resumo:
Sib matings increase homozygosity and, hence, the frequency of detrimental phenotypes caused by recessive deleterious alleles. However, many species have evolved adaptations that prevent the genetic costs associated with inbreeding. We discovered that the highly invasive longhorn crazy ant, Paratrechina longicornis, has evolved an unusual mode of reproduction whereby sib mating does not result in inbreeding. A population genetic study of P. longicornis revealed dramatic differences in allele frequencies between queens, males and workers. Mother-offspring analyses demonstrated that these allele frequency differences resulted from the fact that the three castes were all produced through different means. Workers developed through normal sexual reproduction between queens and males. However, queens were produced clonally and, thus, were genetically identical to their mothers. In contrast, males never inherited maternal alleles and were genetically identical to their fathers. The outcome of this system is that genetic inbreeding is impossible because queen and male genomes remain completely separate. Moreover, the sexually produced worker offspring retain the same genotype, combining alleles from both the maternal and paternal lineage over generations. Thus, queens may mate with their brothers in the parental nest, yet their offspring are no more homozygous than if the queen mated with a male randomly chosen from the population. The complete segregation of the male and female gene pools allows the queens to circumvent the costs associated with inbreeding and therefore may act as an important pre-adaptation for the crazy ant's tremendous invasive success.
Resumo:
Background: About 80% of patients with Crohn's disease (CD) require bowel resection and up to 65% will undergo a second resection within 10 years. This study reports clinical risk factors for resection surgery (RS) and repeat RS. Methods: Retrospective cohort study, using data from patients included in the Swiss Inflammatory Bowel Disease Cohort. Cox regression analyses were performed to estimate rates of initial and repeated RS. Results: Out of 1,138 CD cohort patients, 417 (36.6%) had already undergone RS at the time of inclusion. Kaplan-Meier curves showed that the probability of being free of RS was 65% after 10 years, 42% after 20 years, and 23% after 40 years. Perianal involvement (PA) did not modify this probability to a significant extent. The main adjusted risk factors for RS were smoking at diagnosis (hazard ratio (HR) = 1.33; p = 0.006), stricturing with vs. without PA (HR = 4.91 vs. 4.11; p < 0.001) or penetrating disease with vs. without PA (HR = 3.53 vs. 4.58; p < 0.001). The risk factor for repeat RS was penetrating disease with vs. without PA (HR = 3.17 vs. 2.24; p < 0.05). Conclusion: The risk of RS was confirmed to be very high for CD in our cohort. Smoking status at diagnosis, but mostly penetrating and stricturing diseases increase the risk of RS.
Resumo:
This article presents the notion of the postmodern midwife, defining her as one who takes a relativistic stance toward bio-medicine and other knowledge systems, alternative and indigenous, moving fluidly between them to serve the women she attends. She is locally and globally aware, culturally competent, and politically engaged, working with the resources at hand to preserve midwifery in the interests of women. Her informed relativism is most accessible to professional midwives but is also beginning to characterize some savvy traditional midwives in various countries. Thus the concept of the postmodern midwife can serve as a bridge across the ethnic, racial, and status gaps that divide the professional from the traditional midwife, and as an analytical focal point for understanding how the members of each group negotiate their identities and their roles in a changing world.
Resumo:
RÉSUMÉ Une espèce est rarement composée d'une population unique. Parce que les individus ont des capacités de dispersion limitées et que les paysages sont des mosaïques d'habitats, la plupart des espèces sont plutôt composées de sous-populations connectées par la migration. Cette variation spatiale influence directement la distribution de la variabilité génétique dans et entre les populations. Durant ce travail, nous avons abordé certains des processus populationnels qui ont joué un rôle supposé dans l'apparition de nouvelles espèces au sein du genre Trochulus. Plus précisément, nous avons tenté d'évaluer les impacts respectifs de l'isolement passé (facteurs historiques) et présent (facteurs locaux). Nous avons d'abord pu montrer que les faibles capacités de dispersion des escargots terrestres ont directement influencé leur histoire évolutive à toutes les échelles spatiales et temporelles. En réduisant l'effet homogénéisant de la migration, une faible dispersion maintient dans les populations les traces génétiques d'évènements passés. A l'échelle de la distribution globale de Trochulus villosus, ces traces ont permis de reconstruire une histoire faite d'isolements et d'expansions de populations. En combinant des données génétiques avec une modélisation de la niche climatique passée, il a été possible de proposer un scénario significativement meilleur que toutes les hypothèses alternatives que nous avons testées. A l'échelle locale par contre, l'héritage historique est difficile à distinguer de la dynamique actuelle. Ce fut le cas des lignées mitochondriales du complexe sericeus-hispidus : les deux principales lignées étaient phylogénétiquement éloignées, avaient eu des démographies passées différentes et corrélaient avec des différences morphologiques. D'un autre côté, le flux de gène nucléaire était fort, contredisant l'idée de deux espèces cryptiques isolées reproductivement. Pour pouvoir conclure à la présence ou non de deux espèces, il nous a manqué des informations locales sur la dynamique des populations et les conditions écologiques que l'on trouve dans la région d'étude. Enfin, nous avons pu souligner que la connectivité entre populations d'escargots est soumise à la qualité des habitats et à leur organisation spatiale. Les escargots sont dépendants d'un habitat et s'y adaptent, comme l'indiquent la présence de «poils » uniquement sur la coquille d'espèces vivant dans des habitats humides ou la corrélation entre morphologie et habitat au sein du complexe sericeus-hispidus. Logiquement donc, les escargots migrent préférentiellement au travers d'habitats favorables comme l'a montré la réduction de flux de gènes au travers des prairies chez T. villosus (une espèce forestière). De ces données, nous pouvons supposer que les populations d'escargots en particulier, et des espèces à faible dispersion en général, ont de fortes chances d'être affectées par les changements climatiques, avec de probables implications pour leurs histoires évolutives. SUMMARY : Species rarely consists in a single population. Because individuals have limited dispersal abilities, because landscapes are habitat patchworks, most species are made of several subpopulations connected by migration. This spatial variation has consequences on the distribution of genetic diversity within and between populations, creating a structure among the populations. During the present work, we investigated some of the population processes assumed to have played an important role on the speciation within the genus Trochulus. More specifically, we questioned the respective impacts of past (historical factors) or present (local factors) population isolations. We first could show that the poor dispersal abilities of land snails have had profound impacts on their evolutionary histories at all spatial and temporal scales. Low dispersal maintains a strong signature of past events in the populations by minimising the homogenising effects of geneflow. At the scale of Trochulus villosus global distribution, they allowed to retrieve the detailed history of this species population isolations and expansions. Combining a large genetic dataset with paleo-climatic niche modelling ended up with a historical scenario significantly better than all traditional alternatives we tested. At local scale on the contrary, past events become difficult to tease apart from ongoing processes. This was the case for the divergent mitochondria) lineages within the sericeus-hispidus complex: the two principal lineages appeared to be phylogenetically distant, to have experienced different demographic histories and to correlate with morphological differences. On the other hand, nuclear (present day) geneflow was high, contradicting the idea of two reproductively isolated cryptic species. Information on the local population dynamics and environmental conditions are lacking to be able to decide whether past isolation has indeed resulted here in new species. Finally, we emphasised the importance of the habitat types present in a landscape as well as their spatial organisation for the population connectivity of land snails. These species are tightly dependent on a habitat and adapt to it as shown by thé occurrence of hair-like structures only in species living in humid environments or by the correlation between shell morphology and habitat in the sericeus-hispidus complex. As a result, land snails preferentially migrate through favourable habitats: Trochulus villosus, a forest species, had its geneflow significantly reduced across meadows. From these data, we can hypothesise that the populations of land snails in particular and of low dispersing species in general are likely to be strongly affected by the ongoing climate changes, with potential major consequences on their evolutionary histories.
Resumo:
Any effort to make sense of the complexities of contemporary midwifery must deal not only with biomedical and governmental power structures but also with the definitions such structures impose upon midwives and the ramifications of these definitions within and across national and cultural borders. The international definition of a midwife requires graduations from a government-recognized educational program. Those who have not are not considered midwives but are labeled traditional birth attendants. Since there are myriad local names for midwives in myriad languages, the impact of this naming at local levels can be hard to assess. But on the global scale, the ramifications of the distinction between midwives who meet the international definition and those who do not have been profound. Those who do are incorporated into the health care system. Those who do not remain outside of it, and suffer multiple forms of discrimination as a result.
Resumo:
Mycoplasma hominis is a fastidious micro-organism causing genital and extragenital infections. We developed a specific real-time PCR that exhibits high sensitivity and low intrarun and interrun variabilities. When applied to clinical samples, this quantitative PCR allowed to confirm the role of M. hominis in three patients with severe extragenital infections.