2,443 research outputs found

    Limits on Clouds and Hazes for the TRAPPIST-1 Planets

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    The TRAPPIST-1 planetary system is an excellent candidate for study of the evolution and habitability of M-dwarf planets. Transmission spectroscopy observations performed with the Hubble Space Telescope (HST) suggest the innermost five planets do not possess clear hydrogen atmospheres. Here we reassess these conclusions with recently updated mass constraints and expand the analysis to include limits on metallicity, cloud top pressure, and the strength of haze scattering. We connect recent laboratory results of particle size and production rate for exoplanet hazes to a one-dimensional atmospheric model for TRAPPIST-1 transmission spectra. Doing so, we obtain a physically-based estimate of haze scattering cross sections. We find haze scattering cross sections on the order of 1e-26 to 1e-19 cm squared are needed in hydrogen-rich atmospheres for TRAPPIST-1 d, e, and f to match the HST data. For TRAPPIST-1 g, we cannot rule out a clear hydrogen-rich atmosphere. We also modeled the effects an opaque cloud deck and substantial heavy element content have on the transmission spectra. We determine that hydrogen-rich atmospheres with high altitude clouds, at pressures of 12mbar and lower, are consistent with the HST observations for TRAPPIST-1 d and e. For TRAPPIST-1 f and g, we cannot rule out clear hydrogen-rich cases to high confidence. We demonstrate that metallicities of at least 60xsolar with tropospheric (0.1 bar) clouds agree with observations. Additionally, we provide estimates of the precision necessary for future observations to disentangle degeneracies in cloud top pressure and metallicity. Our results suggest secondary, volatile-rich atmospheres for the outer TRAPPIST-1 planets d, e, and f.Comment: 15 pages, 3 figures, 2 tables, accepted in the Astronomical Journa

    Sequence Detection and Comparative Analysis of the Hv1 and Hv2 Control Regions of Human Mitochondrial DNA by Denaturing High-Performance Liquid Chromatography

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    The objective of this research was the evaluation and forensic validation of Denaturing High-Performance Liquid Chromatography (DHPLC) as a sequencingindependent means of detecting the presence of sequence differences in pair-wise mixtures of non-concordant amplicons of human mitochondrial DNA (mtDNA). The reproducibility and efficacy of DHPLC results, including amplification reproducibility, injection reproducibility, and column-to-column reproducibility were measured, showing negligible assay-to-assay variability. In addition, cross-contamination on the DHPLC columns demonstrated very low level DNA carryover between a high-abundance sample and subsequent zero-volume injections. The accuracy with which DHPLC technology can be used to screen both evidence and control samples in the context of a forensic laboratory was evaluated. This was demonstrated by a number of pair-wise comparisons of each of the forensically relevant amplicons from 95 unrelated individuals in the study, and was in 100% agreement with sequencing data. Thus, DHPLC can be used to detect a diversity of sequence differences (transitions, transversions, insertions and deletions) in the mtDNA D-loop. Accordingly, DHPLC may have utility as a presumptive indicator of mtDNA sequence concordance samples

    A Qualitative Examination of Graduate Advising Relationships: The Advisor Perspective

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    Nineteen counseling psychology faculty members were interviewed regarding their advising relationships with doctoral students. Advisors informally learned to advise from their experiences with their advisor and their advisees and defined their role as supporting and advocating for advisees as they navigated their doctoral program. Advisors identified personal satisfaction as a benefit and time demands as a cost of advising. Good advising relationships were facilitated by advisees’ positive personal or professional characteristics, mutual respect, open communication, similarity in career path between advisor and advisee, and lack of conflict. Difficult relationships were affected by advisees’ negative personal or professional characteristics, lack of respect, research struggles, communication problems, advisors feeling ineffective working with advisees, disruption or rupture of the relationship, and conflict avoidance. Implications for research and training are discussed

    Becoming Psychotherapists: Experiences of Novice Trainees in a Beginning Graduate Class

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    The authors investigated the experiences related to becoming psychotherapists for 5 counseling psychology doctoral trainees in their first prepracticum course. Qualitative analyses of weekly journals indicated that trainees discussed challenges related to becoming psychotherapists (e.g., being self-critical, having troubling reactions to clients, learning to use helping skills), gains made during the semester related to becoming psychotherapists (e.g., using helping skills more effectively, becoming less self-critical, being able to connect with clients), as well as experiences in supervision and activities that helped them cope with their anxieties. Results are discussed in 5 broad areas: feelings about self in role of psychotherapist, awareness of reactions to clients, learning and using helping skills, reactions to supervision, and experiences that fostered growth. Implications for training and research are provided

    Valuing an ecotourism resource : a case study of the Boulders Beach African penguin colony

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    The colony of African Penguins at Boulders, Simon's Town on the southern Cape Peninsula, Western Cape formed in 1985, and is now a major ecotourism destination. The African Penguin is listed as Endangered due in part to competition with commercial fisheries. Improvements in the spatial management of these fisheries could assist with the conservation of the penguins, but would be costly. Various techniques were used to estimate the value of the colony, and to assess its impact on the economy of the southern Peninsula

    A Qualitative Examination of Graduate Advising Relationships:The Advisee Perspective

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    Sixteen 3rd-year counseling psychology doctoral students were interviewed about their relationships with their graduate advisors. Of those students, 10 were satisfied and 6 were unsatisfied with their advising relationships. Satisfied and unsatisfied students differed on several aspects of the advising relationship, including (a) the ability to choose their advisors, (b) the frequency of meetings with their advisors, (c) the benefits and costs associated with their advising relationships, and (d) how conflict was dealt with in the advising relationship. Furthermore, all of the satisfied students reported that their advising relationships became more positive over time, whereas many of the unsatisfied students reported that their advising relationships got worse (e.g., became more distant) over time

    Comparative Leaf Decomposition Rates Including a Non-Native Species in an Urban Ozark Stream

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    Leaf decomposition of three species of native Ozark vegetation was compared to that of one nonnative invasive species. Leaves were placed in an urban gravel-bed stream for 23 days. Changes in mass and condition of the leaves were assessed along with stream temperature, flow, width, depth and discharge. Species native to Eastern North American forests were sycamore (Platanus occidentalis), dogwood (Cornus florida), and redbud (Cercis canadensis). The nonnative species, Japanese (Amur) honeysuckle (Lonicera maackii) comprised approximately 80% of the understory vegetation within the riparian zone of the study reach. After 23 days, Sycamore lost 24.6% mass, dogwood lost 30%, redbud lost 37.5%, and honeysuckle lost 38.3%. Sycamore leaves retained their relative structures the most (ranked 9 on a scale of 1 to 10, with 10 being the most sclerophyllous), and honeysuckle the least (ranked 2 on a scale of 1 to 10). As a result of this study, we suggest that the fast decomposition of leaves at southern latitudes may contribute to the low percentage of detritivores in streams, and that Japanese honeysuckle exacerbates this situation as a result of its more rapid rate of decomposition, therefore potentially depriving univoltine detritivores of nutrients later in their life cycles

    Cyclic hydrostatic pressure and cotton particles stimulate synthesis by human lung macrophages of cytokines in vitro

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    <p>Abstract</p> <p>Background</p> <p>Inhalation of particulates is a leading cause of the development of lung diseases and current understanding of the complex relationship between lung metabolism and airborne particulates is incomplete. It is well established that mechanical load is important in the development of the lung and in lung cell differentiation. The interaction between particle exposure and physical forces on alveolar macrophages is a physiologically relevant issue, but as yet understudied. This study examines the effect of cyclic hydrostatic pressure and cotton particles on synthesis of cytokines by human alveolar macrophages.</p> <p>Methods</p> <p>Alveolar macrophages were obtained from patients with lung disease, either from lavage samples or from lung tissue resection. The commonly used cell line THP-1 was included in the experiments. Cell cultures were exposed to cotton particles and/cyclic hydrostatic pressure (3 or 5 psi); control cultures were exposed to medium only. TNFα, IL-1β and IL-6 were assayed in the culture media using specific ELISAs. Cells were characterized using morphology and markers specific for macrophages (Jenner/Giemsa staining, CD14 and CD68).</p> <p>Results</p> <p>Exposure to cotton particles stimulated cytokine synthesis by macrophages from all three sources; exposure to cyclic hydrostatic pressure alone did not stimulate cytokine synthesis significantly. However, the combination of both particles and cyclic hydrostatic pressure increased the simulation of cytokine synthesis still further. Cell characterization demonstrated that the large majority of cells had a macrophage morphology and were positive for CD14 and CD68.</p> <p>Conclusion</p> <p>These data suggest an interaction between cyclic hydrostatic pressure and particulate exposure, which increases alveolar macrophage cytokine production. This interaction was only observed at the higher cyclic hydrostatic pressure. However, in patient samples, there was considerable variation in the amount by which secretion of an individual cytokine increased and there was also variation in the mechanosensitivity of cells from the three different sources. Cyclic hydrostatic pressure, therefore, may be an important modulator of the response of alveolar macrophages to cotton particles, but the source of the cells may be a confounding factor which demands further investigation.</p

    Intranasal Inhalation of Oxytocin Improves Face Processing in Developmental Prosopagnosia

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    Developmental prosopagnosia (DP) is characterised by a severe, lifelong impairment in face recognition. Little work has attempted to improve face processing in these individuals, but intriguingly, recent evidence suggests oxytocin can improve face processing in both healthy participants and individuals with autism. This study examined whether oxytocin could also improve face processing in individuals with DP. Ten adults with the condition and 10 matched controls were tested using a randomized placebo-controlled double-blind within-subject experimental design (AB-BA). Each participant took part in two testing sessions where they inhaled 24IU of oxytocin or placebo spray and completed two face processing tests: one assessing face memory and the other face perception. Results showed main effects of both participant group and treatment condition in both face processing tests, but the two did not interact. Specifically, the performance of DP participants was significantly lower than control performance under both oxytocin and placebo conditions, but oxytocin improved processing to a similar extent in both groups

    Estimates of genetic parameters of distal limb fracture and superficial digital flexor tendon injury in UK Thoroughbred racehorses

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    A retrospective cohort study of distal limb fracture and superficial digital flexor tendon (SDFT) injury in Thoroughbred racehorses was conducted using health records generated by the British Horseracing Authority (BHA) between 2000 and 2010. After excluding records of horses that had both flat and jump racing starts, repeated records were reduced to a single binary record per horse (&lt;i&gt;n&lt;/i&gt; = 66,507, 2982 sires), and the heritability of each condition was estimated using residual maximum likelihood (REML) with animal logistic regression models. Similarly, the heritability of each condition was estimated for the flat racing and jump racing populations separately. Bivariate mixed models were used to generate estimates of genetic correlations between SDFT injury and distal limb fracture. The heritability of distal limb fracture ranged from 0.21 to 0.37. The heritability of SDFT injury ranged from 0.31 to 0.34. SDFT injury and distal limb fracture were positively genetically correlated. These findings suggest that reductions in the risk of the conditions studied could be attempted using targeted breeding strategies
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