4,766 research outputs found
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Epigenetic Applications in Adverse Outcome Pathways and Chemical Risk Evaluation
Pharmacotherapy of Preterm Labor
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90406/1/j.1875-9114.1993.tb02687.x.pd
Examining the reversibility of long-term behavioral disruptions in progeny of maternal SSRI exposure
Serotonergic dysregulation is implicated in numerous psychiatric disorders. Serotonin plays widespread trophic roles during neurodevelopment; thus perturbations to this system during development may increase risk for neurodevelopmental disorders. Epidemiological studies have examined association between selective serotonin reuptake inhibitor (SSRI) treatment during pregnancy and increased autism spectrum disorder (ASD) risk in offspring. It is unclear from these studies whether ASD susceptibility is purely related to maternal psychiatric diagnosis, or if treatment poses additional risk. We sought to determine whether maternal SSRI treatment alone or in combination with genetically vulnerable background was sufficient to induce offspring behavior disruptions relevant to ASD. We exposed C57BL/6J or Celf6(+/-) mouse dams to fluoxetine (FLX) during different periods of gestation and lactation and characterized offspring on tasks assessing social communicative interaction and repetitive behavior patterns including sensory sensitivities. We demonstrate robust reductions in pup ultrasonic vocalizations (USVs) and alterations in social hierarchy behaviors, as well as perseverative behaviors and tactile hypersensitivity. Celf6 mutant mice demonstrate social communicative deficits and perseverative behaviors, without further interaction with FLX. FLX re-exposure in adulthood ameliorates the tactile hypersensitivity yet exacerbates the dominance phenotype. This suggests acute deficiencies in serotonin levels likely underlie the abnormal responses to sensory stimuli, while the social alterations are instead due to altered development of social circuits. These findings indicate maternal FLX treatment, independent of maternal stress, can induce behavioral disruptions in mammalian offspring, thus contributing to our understanding of the developmental role of the serotonin system and the possible risks to offspring of SSRI treatment during pregnancy
Centrifuge Modeling of Pile-Supported Wharves for Seismic Hazards
Recent earthquakes have highlighted many seismic hazard concerns for western U.S. ports. Port waterfront structures are commonly constructed utilizing pile-supported wharves in combination with rock dike structures retaining a hydraulically placed backfill. Seismic damage is generally attributed to weak soils that are often prevalent in the marine environment (e.g. liquefiable sands, sensitive cohesive soils). In response to past damage, many ports are instigating soil improvement strategies to eliminate or minimize potential occurrences of liquefaction and to increase the strength of cohesive soils. The design of a seismically resilient wharf requires an understanding of its performance during design level earthquakes. Due to the complex nature of pile-supported wharves, state-of-the-art centrifuge modeling techniques are being used to better understand their seismic performance. The authors used the large-scale centrifuge facility at the University of California at Davis. This paper presents details on the construction, instrumentation, and testing of the models. Results from the tests are also included, such as the seismic pile behavior, effect of soil improvement, and the overall behavior
Failure of vaccination to prevent outbreaks of foot-and-mouth disease
Outbreaks of foot-and-mouth disease persist in dairy cattle herds in Saudi Arabia despite revaccination at intervals of 4-6 months. Vaccine trials provide data on antibody responses following vaccination. Using this information we developed a mathematical model of the decay of protective antibodies with which we estimated the fraction of susceptible animals at a given time after vaccination. The model describes the data well, suggesting over 95% take with an antibody half-life of 43 days. Farm records provided data on the time course of five outbreaks. We applied a 'SLIR' epidemiological model to these data, fitting a single parameter representing disease transmission rate. The analysis provides estimates of the basic reproduction number R(0), which may exceed 70 in some cases. We conclude that the critical intervaccination interval which would provide herd immunity against FMDV is unrealistically short, especially for heterologous challenge. We suggest that it may not be possible to prevent foot-and-mouth disease outbreaks on these farms using currently available vaccines
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Examination of Build Height in Ultrasonic Consolidation for Foil Width Specimens Using Supports
Ultrasonic consolidation (UC) is a novel, solid-state, additive manufacturing
fabrication process. It consists of ultrasonic joining of thin metal foils and contour milling
to directly produce functional components in a variety of geometries. The bond between
layers forms when an ultrasonic horn creates a local oscillating stress field at the mating
surfaces. It is commonly theorized that the high frequency vibration under pressure
produces a metallurgical bond without melting the base material. The mechanism behind
the bond is believed to be due to interfacial motion and friction that disrupts surface
contaminants, arguably allowing direct metal to metal contact, and producing sufficient
stress to induce plastic flow and promote the growth of grains across the mating surfaces.
Ignored in this explanation is the role of substrate dimensions on the quality and strength
of the joining process. Researchers have previously examined the effective height
limitations of the build process, i.e., the limiting height to width ratio of one of the
component features being fabricated. This paper extends the experimental work on using
support materials to extend build height on specimens using two different candidate materials, tin bismuth, and a mixture of sugar, corn syrup, and water, referred to as
âcandyâ. Tin bismuth and candy the represent the extremes of a tradeoff between
convenience and stiffness that a support material must possess.Mechanical Engineerin
Defining forgiveness: Christian clergy and general population perspectives.
The lack of any consensual definition of forgiveness is a serious weakness in the research literature (McCullough, Pargament & Thoresen, 2000). As forgiveness is at the core of Christianity, this study returns to the Christian source of the concept to explore the meaning of forgiveness for practicing Christian clergy. Comparisons are made with a general population sample and social science definitions of forgiveness to ensure that a shared meaning of forgiveness is articulated. Anglican and Roman Catholic clergy (N = 209) and a general population sample (N = 159) completed a postal questionnaire about forgiveness. There is agreement on the existence of individual differences in forgiveness. Clergy and the general population perceive reconciliation as necessary for forgiveness while there is no consensus within psychology. The clergy suggests that forgiveness is limitless and that repentance is unnecessary while the general population suggests that there are limits and that repentance is necessary. Psychological definitions do not conceptualize repentance as necessary for forgiveness and the question of limits has not been addressed although within therapy the implicit assumption is that forgiveness is limitless.</p
Developing autonomous learning in first year university students using perspectives from positive psychology
Autonomous learning is a commonly occurring learning outcome from university study, and it is argued that students require confidence in their own abilities to achieve this. Using approaches from positive psychology, this study aimed to develop confidence in firstâyear university students to facilitate autonomous learning. Psychological character strengths were assessed in 214 students on day one at university. Two weeks later their top three strengths were given to them in study skills modules as part of a psychoâeducational intervention designed to increase their selfâefficacy and selfâesteem. The impact of the intervention was assessed against a control group of 40 students who had not received the intervention. The results suggested that students were more confident after the intervention, and that levels of autonomous learning increased significantly compared to the controls. Character strengths were found to be associated with selfâefficacy, selfâesteem and autonomous learning in ways that were theoretically meaningful
An All-Permanent Magnet 10 GHz "Multi-Mode" ECR Ion Source for the Production of Metallic Ions
In order to measure cross sections for charge-changing processes in collisions between ions in our ion-ion [1] experiment one ion beam has to be produced on a high voltage terminal. Since there are restrictions concerning the available space and electrical power an all-permanent magnet 10 GHz electron cyclotron resonance ions source has been built earlier [2]. This ion source is in operation and produces multiply charged ions from gaseous elements with sufficient intensities. Now there is a growing interest in the use of ions from metallic elements. For this purpose a new fully permanent 10 GHz ECR ion source has been constructed and tested. The main feature of this ion source is a stepped plasma chamber (see fig. 1) which allows the propagation of higher microwave modes in the plasma and also results in a bigger plasma volume. The longitudinal magnetic field for the axial plasma confinement is produced by two ring magnets whereas the radial magnetic field is formed by a Halbach-type [3] hexapole magnet. The microwave is produced in a frequency-tunable magnetron (8.75-10.5 GHz, 250 Watt max.) and coupled to the plasma via a coaxial line. The applied microwave frequency turned out to be one of the most important parameters when optimizing the ion source on different charge states since a variation of the magnetic field is not possible with the present configuration
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The role of claw color in species recognition and mate choice in a fiddler crab
Many animal signals are brightly colored and convey information about species identity as well as information about individual conspecifics. Colorful bird and lizard signals have received much attention, and many studies have related specific spectral properties of these signals to variation in mating success and territory defense. Far less attention has been given to invertebrates even though there are spectacularly colorful species. The enlarged claw of the male banana fiddler crab Austruca mjoebergi, for example, is bright yellow and contrasts vividly against the mudflat substrate. It is used in waving displays to attract females and in male territory defense and combat. Claw color varies among males in the degree of âyellowness,â ranging very pale yellow to orange. In this study we examined female responses to claw color variation in two-choice tests using robotic crabs. We found that although females strongly discriminate against colors that fall outside the natural range of intensity, hue and chroma, they show no consistent preferences for different claw colors within the natural range, and no single component of claw color (hue, chroma or intensity) independently affected female choices. Using three-choice tests, we also showed that female preferences induce stabilizing selection on male claw color. We conclude that, although claw color is sufficient to facilitate species recognition, it is unlikely to be used in intraspecific mate choice to provide information about male quality
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