4,953 research outputs found

    The mass-velocity and intensity-velocity relations in jet-driven molecular outflows

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    We use numerical simulations to examine the mass-velocity and intensity-velocity relations in the CO J=2-1 and H2_2 S(1)1-0 lines for jet-driven molecular outflows. Contrary to previous expectations, we find that the mass-velocity relation for the swept-up gas is a single power-law, with a shallow slope ≃−1.5\simeq -1.5 and no break to a steeper slope at high velocities. An analytic bowshock model with no post-shock mixing is shown to reproduce this behaviour very well. We show that molecular dissociation and the temperature dependence of the line emissivity are both critical in defining the shape of the line profiles at velocities above ∼\sim 20 km s−1^{-1}. In particular, the simulated CO J=2-1 intensity-velocity relation does show a break in slope, even though the underlying mass distribution does not. These predicted CO profiles are found to compare remarkably well with observations of molecular outflows, both in terms of the slopes at low and high velocities and in terms of the range of break velocities at which the change in slope occurs. Shallower slopes are predicted at high velocity in higher excitation lines, such as H2_2 S(1)1-0. This work indicates that, in jet-driven outflows, the CO J=2-1 intensity profile reflects the slope of the underlying mass-velocity distribution only at velocities ≤\le 20 km/s, and that higher temperature tracers are required to probe the mass distribution at higher speed.Comment: 6 pages, 8 figures. Accepted for publication in Astronomy and Astrophysic

    The effect of prior victory or defeat in the same site as that of subsequent encounter on the determination of dyadic dominance in the domestic hen

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    We examined the effect of prior victory or defeat in the same site as that of a subsequent encounter on the outcome of dyadic encounter of domestic hens by placing them in two situations: In the first set of dyads, two unacquainted hens having experienced prior victory were introduced in the site where one had experienced victory. In the second set, two unacquainted hens having experienced defeat were introduced in the site where one had recently lost. Results indicate that victories are equally shared between individuals with prior victory experiences, while familiarity with the meeting site did not give any advantage. However, hens having previously lost were disadvantaged when the encounter occurred in the same site as that of their prior defeat. This demonstrates that previous social experience in a site is more important on the outcome of subsequent encounters for losers than winners. Losers seem to associate the site with the stressful effect of losing or being more easily dominated

    A CFD technique for estimating the flow distortion effects on LiDAR measurements when made in complex flow fields

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    The effect of flow distortion on the measurements produced by a LiDAR or SoDAR in close proximity to either complex terrain or a structure creating localised flow distortion is difficult to determine by analytical means. Also, as LiDARs and SoDARs are not point measurement devices, the techniques they employ for velocity measurements leads to complexities in the estimation of the effect of flow distortion on the accuracy of the measurements they make. This paper presents a method by which the effect of flow distortion on measurements made by a LiDAR in a distorted flow field may be determined using computational fluid dynamics. The results show that the error created by the flow distortion will cause the vector measured by a LiDAR to differ significantly from an equivalent point measurement. However, the results of the simulation show that, if the LiDAR is being used to measure the undisturbed flow field above a structure which creates highly localised flow distortion, the LiDAR results are less affected by the distortion of the local flow field than data acquired by a point measurement technique such as a cup anemometer

    Child Massage Integrated Therapy: A Preliminary Intervention Manual for Psychological Trauma Treatment

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    This dissertation introduces an original preliminary treatment manual as a guide for mental health providers interested in adding a research-informed massage therapy component to traditional child trauma psychotherapy.Child Massage Integrated Therapy (CMIT) offers a standardized protocol to support the implementation of a replicable treatment modality that fosters critical somatic resources for traumatized children within real-world settings. The multidisciplinary field of interpersonal neurobiology, including attachment and polyvagal theories, as well as the concept of interoceptive awareness, are the theoretical constructs informing the proposed model of care. A review of the research literature recognizing massage therapy\u27s role in creating a regulating mind/body experience provides the fundamental basis for pursuing this line of intervention as a component of a phase-oriented psychological trauma treatment

    On the Coupling between Helium Settling and Rotation-Induced Mixing in Stellar Radiative Zones: II- Application to light elements in population I main-sequence stars

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    In the two previous papers of this series, we have discussed the importance of t he μ\mu-gradients due to helium settling on rotation-induced mixing, first in a n approximate analytical way, second in a 2D numerical simulation. We have found that, for slowly rotating low mass stars, a process of ``creeping paralysis" in which the circulation and the diffusion are nearly frozen may take place below the convective zone. Here we apply this theory to the case of lithium and beryll ium in galactic clusters and specially the Hyades. We take into account the rota tional braking with rotation velocities adjusted to the present observations. We find that two different cells of meridional circulation appear on the hot side of the "lithium dip" and that the "creeping paralysis" process occurs, not dir ectly below the convective zone, but deeper inside the radiative zone, at the to p of the second cell. As a consequence, the two cells are disconnected, which ma y be the basic reason for the lithium increase with effective temperature on thi s side of the dip. On the cool side, there is just one cell of circulation and t he paralysis has not yet set down at the age of the Hyades; the same modelisatio n accounts nicely for the beryllium observations as well as for the lithium ones .Comment: 13 printed pages, 10 figures. ApJ, in press (April 20, 2003

    Households' preferences and willingness to pay for multiple use water services in rural areas of South Africa: An analysis based on choice modelling

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    Financing of multiple use (i.e. domestic and productive) water services was identified as an important ingredient to ensure improved water access for rural poor and broaden livelihood options in South Africa. Following the principles of integrated water resource management (IWRM), efficient, equitable and sustainable investments in improved water services should be based on a thorough understanding of actual demand by consumers. Comprehensive studies looking at multiple use water services are not common in South African rural areas, where most of the economic analyses focus on either domestic or irrigation water demand. This study aims at filling this gap by assessing the household demand for multiple use water services in Sekororo-Letsoalo area in the Limpopo Province. Choice modelling is the approach used to identify the attributes determining demand for water services and quantify their relative importance. Results show that households in rural areas are willing to pay for improvements in water services. Due to the current poor level of water services in the area, users are primarily concerned with basic domestic uses and, consequently, demand for productive uses is low. Only households already relatively well served are interested in engaging in multiple water uses

    Alterations in prefrontal-limbic functional activation and connectivity in chronic stress-induced visceral hyperalgesia.

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    Repeated water avoidance stress (WAS) induces sustained visceral hyperalgesia (VH) in rats measured as enhanced visceromotor response to colorectal distension (CRD). This model incorporates two characteristic features of human irritable bowel syndrome (IBS), VH and a prominent role of stress in the onset and exacerbation of IBS symptoms. Little is known regarding central mechanisms underlying the stress-induced VH. Here, we applied an autoradiographic perfusion method to map regional and network-level neural correlates of VH. Adult male rats were exposed to WAS or sham treatment for 1 hour/day for 10 days. The visceromotor response was measured before and after the treatment. Cerebral blood flow (CBF) mapping was performed by intravenous injection of radiotracer ([(14)C]-iodoantipyrine) while the rat was receiving a 60-mmHg CRD or no distension. Regional CBF-related tissue radioactivity was quantified in autoradiographic images of brain slices and analyzed in 3-dimensionally reconstructed brains with statistical parametric mapping. Compared to sham rats, stressed rats showed VH in association with greater CRD-evoked activation in the insular cortex, amygdala, and hypothalamus, but reduced activation in the prelimbic area (PrL) of prefrontal cortex. We constrained results of seed correlation analysis by known structural connectivity of the PrL to generate structurally linked functional connectivity (SLFC) of the PrL. Dramatic differences in the SLFC of PrL were noted between stressed and sham rats under distension. In particular, sham rats showed negative correlation between the PrL and amygdala, which was absent in stressed rats. The altered pattern of functional brain activation is in general agreement with that observed in IBS patients in human brain imaging studies, providing further support for the face and construct validity of the WAS model for IBS. The absence of prefrontal cortex-amygdala anticorrelation in stressed rats is consistent with the notion that impaired corticolimbic modulation acts as a central mechanism underlying stress-induced VH

    Anatomical Differences of Corneal Surface Parameters

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    Purpose: The aim of this study was to analyze possible anatomical differences of corneal surface parameters in the sample of population and between the genders. Methods: This study is presenting the sample of population which has consisted of 1354 subjects, 794 female and 560 male eyes. Subjects were chosen randomly. To determine and evaluate all values of corneal surface parameters, auto refractor keratometer with Placido disc (KR 8100P, Topcon, Japan) and the program Software Corneal Analyzer, Version 3.0 were used. The results were registered and then processed statistically. Results: From a large amounts of data, tere are chosen only the results in this study that showed statistically significant (p<0. 05) differences between right and left eye and between the genders. Found variations are in: the steepest meridian, the axis of the steepest meridian, corneal astigmatism, astigmatic difference and corneal diameter (HVID). Conclusion: The study shows that in optometric practice is also important to pay attention not only to functional but also individual anatomical parameters of corneal surface
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