2,959 research outputs found

    Fracture through cavitation in a metallic glass

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    The fracture surfaces of a Zr-based bulk metallic glass exhibit exotic multi-affine isotropic scaling properties. The study of the mismatch between the two facing fracture surfaces as a function of their distance shows that fracture occurs mostly through the growth and coalescence of damage cavities. The fractal nature of these damage cavities is shown to control the roughness of the fracture surfaces

    Non-classroom special education effectiveness for students with severe developmental, emotional and behavioral disorders

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    AbstractFew studies exist on the effectiveness of special education day treatment for student youth with emotional and behavioral disorders so severe that they cannot be educated in a day treatment setting. Case studies were performed with two youth who had failed previous special education and day treatment programs. Youth participated in a special education program in a private, non-profit, behavioral health and education agency. Unique to this program were the non-traditional, non-classroom based components of education and therapies. Comprehensive, interdisciplinary interventions resulted in progress for these two youth in areas of medical health, violent /aggressive behavior, communication and social skills, community involvement and educational skills. Additional study needs to be performed on more students along with empirical testing of specific interventions with comparison cases

    Maternal age, psychological maturity, parenting cognitions, and mother-infant interaction

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    In the context of the trend toward delayed childbearing, the aim of this study was to examine relations among maternal age and the quality of maternal interactive behavior at 7 months assessed using sensitivity and mind-mindedness, while also considering whether age effects were attributable to psychological maturity and parenting cognitions. Participants were 150 Australian mothers (mean age 33-years) and their firstborn infants who were participating in a prospective study of parenthood. Path analysis showed maternal age had both direct and indirect associations with maternal interactive behavior. Older mothers made more mind-related comments to their infants. They were also more sensitive; however, this effect was indirect and explained by greater psychological maturity (hardiness) and a more internal locus of control with regard to parenting. Results suggest that older maternal age may confer some benefits in terms of responsive parenting in infancy

    Subjective Assessment of Sleep Quality Across the Menstrual Cycle in Women with Premenstrual Dysphoric Disorder

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    Existing evidence demonstrates that sleep structure varies across the menstrual cycle in healthy women (1). These variations could be more severe in women suffering from premenstrual dysphoric disorder (PMDD) (2). In a previous study of healthy women, subjective sleep quality was shown to be constant across both phases of the menstrual cycle (3). The current study aims to test whether there exists a variation in subjective sleep quality of PMDD sufferers across the follicular and luteal phases of the menstrual cycle

    Étude expĂ©rimentale des transferts d'eau provoquĂ©s par l'irrigation sur une parcelle en moyenne vallĂ©e du fleuve SĂ©nĂ©gal

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    Alors que l'irrigation paraĂźt ĂȘtre le recours essentiel face aux besoins croissants de la population mondiale en cĂ©rĂ©ales, la dĂ©gradation des sols et des eaux annihile presque totalement les efforts d'amĂ©nagement. Aussi l'Ă©tude de la dĂ©gradation des sols dans la moyenne vallĂ©e du fleuve SĂ©nĂ©gal constitue l'un des quatre objectifs du pĂŽle de recherches sur les systĂšmes irriguĂ©s sahĂ©liens qui regroupe quatre pays dont le Mali, la Mauritanie, le Niger et le SĂ©nĂ©gal. Le suivi de l'Ă©volution des eaux et des sols sous culture apparaĂźt indispensable pour garantir une agriculture irriguĂ©e rentable et durable dans la zone. Dans cette rĂ©gion, les risques de dĂ©gradation des sols font suite Ă  l'effet de deux processus de dĂ©gradation que sont l'alcalinisation et la salinisation des sols. Ces types de dĂ©gradation sont fortement corrĂ©lĂ©s Ă  la remontĂ©e des nappes d'eaux souterraines. Dans cet article, l'Ă©tude des transferts d'eau dans les parcelles irriguĂ©es par le biais d'un suivi expĂ©rimental " in situ " met en Ă©vidence les relations existantes entre les eaux d'irrigation et les mouvements de la nappe. L'Ă©tude a permis une meilleure comprĂ©hension de la dynamique hydrique au sein de la parcelle : saturation du profil et processus de recharge de la nappe. Elle a Ă©galement permis de montrer que les Ă©changes avec la nappe pendant la pĂ©riode d'irrigation sont nĂ©gligeables. Cette pratique de la riziculture inondĂ©e, entraĂźne une variation de stock importante qui reprĂ©sente plus de 40% des apports et qui se traduit par une remontĂ©e de nappe de prĂšs de 2 mĂštres.Whereas irrigation appears to be the main approach to satisfy the growing worldwide demand for cereal, soil and water degradation continues to be an on-going problem in agriculture development. One of the main four concerns of the regional group for research on Sahelian irrigated systems (including Mali, Mauritania, Niger and Senegal) is soil degradation in the middle Senegal River valley. These soils are subject to various forms of degradation, mainly from salinisation and/or alkalinisation. These degradation processes are strongly correlated with water table dynamics, with water level fluctuations being significant. Therefore, to guarantee sustainable development of irrigated agriculture in the area, irrigation must be coupled with complete and permanent monitoring of soil and water quality.In this paper, we present a complete study concerning water transfer in irrigated plots and its effects on the groundwater table. The experimental site is located in the Podor region, at 16°.37'N, 14°.52'W in the Donaye irrigated area. The surface area is about 50 ha. Water supply is assured by filling a main channel using a group of pumps on the DouĂ© River. Irrigation of the parcels is performed with siphons from this channel. The experimental plot of 0.33 ha is used for an underwater rice crop. One or two rice crop production harvests are made every year, with the decision been taken by the farmers. There is no drainage system in the area.The experimental plot was equipped with 8 piezometers located along a stream line. One is situated between the plot and the river in order to study the water movements caused by the exchange between the groundwater and the water in the river. Three are situated in the plot, one close to the DouĂ© River, one in the middle of the plot and one near a dam, which is the opposite boundary compared to the river. Four other piezometers are located beyond the dam to estimate groundwater input and output at this boundary. Five tensiometers at 20, 40, 60, 95 and 135 cm depth are placed close to the piezometers located in the plot. Four water content profiles were measured during the irrigation period at depths 20, 40, 60 95 and 135 cm and the irrigation was performed over 84 days.The water table level variations at 2 meters were recorded. The groundwater inflow decreased during the first part of the irrigation period due to infiltration below the irrigated experimental plot. This inflow increased during a second period due to water level variations in the river close to this site. At the output, the head gradient did not vary appreciably and the outflow was assumed to be constant during the observation period. Moreover, this gradient is quite low and the flow rate is very low. The water content and pressure profiles clearly show the infiltration of water in the soil during irrigation. The head gradients show the water movement in the unsaturated soil during infiltration and evaporation. Upward flow due to evaporation is observed at about 10 days after irrigation. The last measured water profile (76 days after the end of irrigation) shows that evaporation modifies the water content profile until at least a depth of 120 cm.The water balance during the irrigation period showed that the input due to irrigation and precipitation was equal to 4150 m3. The evapotranspiration output was estimated to be 2370 m3. Groundwater exchange at the downstream boundary can be neglected during the duration of irrigation (84 days), since the average hydraulic gradient remained low (less than 0.8 %) and the hydraulic conductivity of the aquifer was not important (about 250 cm/day). It was assumed that the water storage quantified with the rise of the groundwater level was equal to the difference between surface input and evapotranspiration (more than 40 % of the contributions), leading to a 27 % change in water content, which is quite reasonable for this type of soil (clay).The stored water was then recovered by evapotranspiration and groundwater outflow at the plot boundaries. We are away from a reasonable irrigation that would reduce the used water quantity and decrease the risk of soil degradation. This study allows a better understanding of the water dynamics in the experimental plot, which includes soil saturation, recharge processes, and exchanges between the aquifer and the river

    Anxiolytic Effect of Melatonin in Premenstrual Dysphoric Disorder

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    Increases in anxiety levels during the late-luteal phase of the menstrual cycle form important diagnostic criteria of premenstrual dysphoric disorder (PMDD) (1). Evidence exists to support the hypothesis that tolerance to endogenous levels of melatonin might occur during the luteal phase in PMDD (2, 3). It was hypothesized that slow release (SR) melatonin administration during the luteal phase of the menstrual cycle of participants with PMDD could significantly lower anxiety levels measured by self-report

    Polarization squeezing with cold atoms

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    We study the interaction of a nearly resonant linearly polarized laser beam with a cloud of cold cesium atoms in a high finesse optical cavity. We show theoretically and experimentally that the cross-Kerr effect due to the saturation of the optical transition produces quadrature squeezing on both the mean field and the orthogonally polarized vacuum mode. An interpretation of this vacuum squeezing as polarization squeezing is given and a method for measuring quantum Stokes parameters for weak beams via a local oscillator is developed

    An experimental evaluation of the benefits and costs of providing fertility information to adolescents and emerging adults

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    STUDY QUESTION Does the provision of fertility (compared to control) information affect fertility-related knowledge, perceived threat of infertility, anxiety, physical stress and fertility plans in adolescents and emerging adults? SUMMARY ANSWER The provision of fertility information was associated with increased fertility knowledge (emerging adults) and greater infertility threat (adolescents and emerging adults). WHAT IS KNOWN ALREADY According to fertility education research, adolescents and emerging adults know less than they should know about fertility topics. Fertility knowledge can be improved through the provision of information in older adults. STUDY DESIGN, SIZE, DURATION Experimental design. Secondary and university students completed pre-information questionnaires, were randomly assigned via computer to an experimental group, read either fertility (FertiEduc group) or healthy pregnancy information (Control group), and completed post-information questionnaires. Data were collected in group sessions via an online portal. PARTICIPANTS/MATERIALS, SETTING, METHODS Eligible participants were aged 16–18 (adolescents) or 21–24 years (emerging adults), childless, not currently pregnant (for men, partner not pregnant) or trying to conceive, presumed fertile and intending to have a child in the future. Of the 255 invited, 208 (n = 93 adolescents, n = 115 emerging adults) participated. The FertiEduc group received ‘A Guide to Fertility’, four online pages of information about fertility topics (e.g. ‘When are men and women most fertile?’) and the Control group received four online pages from the National Health Service (NHS) pregnancy booklet ‘Baby Bump and Beyond’. Participants completed a questionnaire (fertility knowledge, perceived threat of infertility, anxiety, physical stress and fertility plans, moderators) prior to and after the provision of information. Mixed factorial analysis of variance was used to examine the effects of information provision and hierarchical multiple regression to assess potential moderators of knowledge. MAIN RESULTS AND THE ROLE OF CHANCE The FertiEduc and Control groups were equivalent on age, gender, disability, relationship status and orientation at baseline. Results showed that fertility information significantly increased fertility knowledge for emerging adults only (P < 0.001) and threat of infertility for emerging adults and adolescents (P = 0.05). The moderators were not significant. Participation in the study was associated with an increase in feelings of anxiety but a decrease in physical stress reactions. Adolescents had more optimal fertility plans compared to emerging adults due to being younger. LIMITATIONS, REASONS FOR CAUTION This was an experimental study on a self-selected sample of men and women from selected educational institutions and only short term effects of information were studied. WIDER IMPLICATIONS OF THE FINDINGS Provision of fertility information can have benefits (increased fertility knowledge) but also costs (increase potential threat of infertility). Adolescents find fertility information positive but do not learn from it. Fertility education should be tailored according to age groups and created to minimise negative effects. Longitudinal examination of the effects of fertility information in multi-centre studies is warranted and should include measures of perceived threat of infertility

    Inclusive 2H(3He,t) reaction at 2 GeV

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    The inclusive 2H(3He,t) reaction has been studied at 2 GeV for energy transfers up to 500 MeV and scattering angles from 0.25 up to 4 degrees. Data are well reproduced by a model based on a coupled-channel approach for describing the NN and N Delta systems. The effect of final state interaction is important in the low energy part of the spectra. In the delta region, the cross-section is very sensitive to the effects of Delta-N interaction and Delta N - NN process. The latter has also a large influence well below the pion threshold. The calculation underestimates the experimental cross-section between the quasi-elastic and the delta peaks; this is possibly due to projectile excitation or purely mesonic exchange currents.Comment: 9 pages, 9 figures, accepted for publication in EPJ
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