148 research outputs found

    Bed-slope-related diffusion of an erodible hump

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    In certain conditions, the bed slope has a substantial influence on sediment transport rates and hence morphological evolution. Approaches to account for such influence usually suffer from a high degree of empiricism and/or mathematical complexity. We propose a bed slope related diffusivity parameter, derived from a morphodynamic model previously validated against empirical data for bedload transport on horizontal and steep sloping channels. The proposed diffusivity parameter is easy to include in a conventional morphodynamic model via the modification of a typical bedload formula originally developed for sediment transport in a nearly horizontal channel. A conventional model modified through this parameter proves to yield enhanced results in the case study of a submerged migrating sandbar, by avoiding the generation of unrealistic high-frequency oscillations in the bed profile, yet permitting the expected steepening of its downstream face with time. Other models derived for sloping channels do not satisfy the latter condition. It is also shownthat unre-alistic oscillations can be avoided through numerical means; however, their use should be interpreted carefully from a hydrodynamic and sedimentological viewpoint

    Fire Alters Plant Microbiome Assembly Patterns: Integrating the Plant and Soil Microbial Response to Disturbance

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    It is increasingly evident that the plant microbiome is a strong determinant of plant health. While the ability to manipulate the microbiome in plants and ecosystems recovering from disturbance may be useful, our understanding of the plant microbiome in regenerating plant communities is currently limited. Using 16S ribosomal RNA (rRNA) gene and internal transcribed spacer (ITS) region amplicon sequencing, we characterized the leaf, stem, fine root, rhizome, and rhizosphere microbiome of \u3c 1-yr-old aspen saplings and the associated bulk soil after a recent high-intensity prescribed fire across a burn severity gradient. Consistent with previous studies, we found that soil microbiomes are responsive to fire. We extend these findings by showing that certain plant tissue microbiomes also change in response to fire. Differences in soil microbiome compositions could be attributed to soil chemical characteristics, but, generally, plant tissue microbiomes were not related to plant tissue elemental concentrations. Using source tracking modeling, we also show that fire influences the relative dominance of microbial inoculum and the vertical inheritance of the sapling microbiome from the parent tree. Overall, our results demonstrate how fire impacts plant microbiome assembly, diversity, and composition and highlights potential for further research towards increasing plant fitness and ecosystem recovery after fire events

    The impact of sediment flux and calibre on flood risk in the Kathmandu Valley, Nepal

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    AbstractThis paper investigates how variations in sediment supply, grain size distribution and climate change affect channel morphology and flood inundation in the Nakkhu River, Kathmandu, Nepal. Climate change‐induced extreme rainfall is expected to increase flood intensity and frequency, causing severe flooding in the Kathmandu basin. The upper reaches of the Nakkhu River are susceptible to landslides and have been impacted by large‐scale sand mining. We simulate potential erosion and deposition scenarios along a 14 km reach of the Nakkhu River using the landscape evolution model CAESAR‐Lisflood with a 10 m digital elevation model, field‐derived sediment grain size data, daily discharge records and flood forecast models. In a series of numerical experiments, we compare riverbed profiles, cross‐sections, flood extent and flow depths for three scenarios (1.2‐, 85‐ and 1000‐year return period floods). For each scenario, the model is first run without sediment transport and then with sediment transport for three grain size distributions (GSDs) (observed average, finer and coarser). In all cases, the inclusion of sediment led to predicted floods of a larger extent than estimated without sediment. The sediment grain size distribution was found to have a significant influence on predicted river morphology and flood inundation, especially for lower magnitude, higher probability flood events. The results emphasise the importance of including sediment transport in hydrological models when predicting flood inundation in sediment‐rich rivers such as those in and around the Himalaya.</jats:p

    Impact of clerkship in the attitudes toward psychiatry among Portuguese medical students

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    <p>Abstract</p> <p>Background</p> <p>Given the shortage of human resources and the launching of a new Mental Health Plan, recruitment of psychiatrists is currently a major concern in Portugal, as well as in several other countries. Medical students' attitude toward psychiatry has been pointed as a predictor of recruitment. This study aims to evaluate the medical students' perception of psychiatry before and after a clerkship, and the impact on their intention to pursue psychiatry as a future specialty option.</p> <p>Methods</p> <p>Two self-report questionnaires were administered to all 6<sup>th </sup>year students in a medical school in Lisbon, before and after a 4-weeks full-time psychiatric clerkship, in order to evaluate attitudes toward psychiatry and intention to follow psychiatry in the future. Statistical analysis included Wilcoxon and Chi-square tests.</p> <p>Results</p> <p>153 students (60.8% female) filled in both questionnaires (no dropouts). After the clerkship, there was a significant improvement regarding the overall merits of psychiatry, efficacy, role definition and functioning of psychiatrists, use of legal powers to hospitalize patients and specific medical school factors. There was also a significant increase of students decided or considering the possibility to take a residency in psychiatry.</p> <p>However, perceptions of low prestige and negative pressure from family and peers regarding a future choice of psychiatry remained unchanged in about one-third of the students.</p> <p>Conclusions</p> <p>The results indicate clearly that the clerkship had a favorable overall impact on the student attitude towards psychiatry, as well as in the number of students considering a future career in psychiatry. Attitudes toward psychiatry seems a promising outcome indicator of the clerkship's quality, but further research is needed in order to assess its reliability as a sound predictor of recruitment.</p

    EB Ford revisited: assessing the long-term stability of wing-spot patterns and population genetic structure of the meadow brown butterfly on the Isles of Scilly

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Data files of wing spot sizes and AFLP genotypes available from the Dryad Digital Repository: http://dx.doi.org/10.5061/dryad.j7v42.Understanding selection in the wild remains a major aim of evolutionary ecology and work by Ford and colleagues on the meadow brown butterfly Maniola jurtina did much to ignite this agenda. A great deal of their work was conducted during the 1950s on the Isles of Scilly. They documented island-specific wing-spot patterns that remained consistent over about a decade, but patterns on some islands changed after environmental perturbation. It was suggested that these wing-spot patterns reflected island-specific selection and that there was little migration between islands. However, genetic studies to test the underlying assumption of restricted migration are lacking and it is also unknown whether the originally described wing-spot patterns have persisted over time. We therefore collected female butterflies from five of Ford's original study locations, including three large islands (St Mary's, St Martin's and Tresco) and two small islands (Tean and St Helen's). Wing-spot patterns had not changed appreciably over time on three of the islands (two large and one small), but were significantly different on the other two. Furthermore, analysis of 176 amplified fragment length polymorphisms revealed significant genome-wide differentiation among the five islands. Our findings are consistent with Ford's conclusions that despite the close proximity of these islands, there is restricted gene flow among them.Heredity advance online publication, 2 November 2016; doi:10.1038/hdy.2016.94.We thank the Genetics Society for a fieldwork grant (to DJH) that funded the collection trip and DJH thanks Mike Johnson for sparking interest in this area. SWB is supported by the Australian Research Council and a Ramsay Fellowship, NW by a Royal Society Wolfson Fellowship and NERC and DJH by the Leverhulme Trust

    Compliance with herpes zoster vaccination in young and adult individuals in two regions of Italy

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    Background: The purpose of this work was to explore the knowledge and acceptance of Varicella Zoster Virus (VZV)- Herpes Zoster (HZ) vaccination in the general Italian population, where the HZ vaccine has not yet been distributed, using a prevalence study of subjects from two regions in Italy. Methods: A group of 3,173 individuals were interviewed using a questionnaire. The youngest age group (≤ 20 year) was composed of students interviewed at university. The middle age group (21-40 years) and the older age group (≥ 41 years) were interviewed by general practitioners in their office. Results: In both regions, the majority of subjects had been infected with varicella, and only 165 (5.2%) subjects reported receiving the VZV vaccination. Regarding HZ, 2,749 (86.6%) individuals stated that they knew of the virus and 2,233 (70%) were willing to be vaccinated against HZ. The majority of people willing to be vaccinated were in the middle and older age groups (36.6% and 44.7%, respectively). Conclusion: Compliance versus vaccination results were satisfactory and probably, with the upcoming availability of the HZ vaccine in Italy, adults will be favourably disposed towards vaccination

    Relating Differently to Intrusive Images: The Impact of Mindfulness Based Cognitive Therapy (MBCT) on Intrusive Images in Patients With Severe Health Anxiety (Hypochondriasis).

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    Recurrent distressing intrusive images are a common experience in hypochondriasis. The aim of the current study was to assess the impact of Mindfulness-Based Cognitive Therapy (MBCT) for hypochondriasis on the occurrence and nature of distressing intrusive imagery in hypochondriasis. A semi-structured interview was used to assess intrusive imagery, and an adapted version of the Southampton Mindfulness Questionnaire (SMQ) was used to assess participants’ relationship with their intrusive images. A consecutive series of participants (N = 20) who were receiving MBCT for hypochondriasis as part of an ongoing research program were assessed prior to participating in an 8-week MBCT intervention, immediately following the intervention, and at three month follow-up. As compared to the baseline assessment, the frequency of intrusive images, the distress associated with them, and the intrusiveness of the images were all significantly reduced at the post-MBCT assessment. Participants’ adapted SMQ scores were significantly increased following the MBCT intervention, suggesting that participants’ relationship with their intrusive images had changed in that they had developed a more ‘mindful’ and compassionate response to the images when they did occur. Effect sizes from pre- to post-intervention were medium to large (Cohen’s d = 0.75 - 1.50). All treatment gains were maintained at 3 month follow-up. Results suggest that MBCT may be an effective intervention for addressing intrusive imagery in hypochondriasis

    Abuse in Women and Men with and without Functional Gastrointestinal Disorders

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    We aimed to investigate the history of abuse in childhood and adulthood and health-related quality of life (HRQL) in women and men with FGID in the general adult population. A cross-sectional study in a random population sample (n = 1,537, 20–87 years) living in Östhammar municipality, Sweden, in 1995 was performed. Persons with FGID (n = 141) and a group of abdominal symptom-free controls (SSF, n = 97) were selected by means of a validated questionnaire assessing gastrointestinal symptoms (the ASQ). Abuse, anxiety and depression (the HADS) and HRQL (the PGWB) were measured. Women with FGID had a higher risk of having a history of some kind of abuse, as compared with the SSF controls (45% vs.16%, OR = 2.0, 95% CI: 1.01–3.9; SSF = 1), in contrast to men (29% vs. 24% n.s.). Women with a history of abuse and FGID had reduced HRQL 91 (95% CI 85–97) as compared with women without abuse history 100 (95% CI 96–104, P = 0.01, “healthy” = 102–105 on PGWB). Childhood emotional abuse was a predictor for consulting with OR = 4.20 (95% CI: 1.12–15.7.7). Thus, previous abuse is common in women with FGID and must be considered by the physician for diagnosis and treatment of the disorder

    Co-rumination buffers the link between social anxiety and depressive symptoms in early adolescence

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    Objectives: We examined whether co-rumination with online friends buffered the link between social anxiety and depressive symptoms over time in a community sample. Methods: In a sample of 526 participants (358 girls; Mage = 14.05) followed at three time points, we conducted a latent cross-lagged model with social anxiety, depressive symptoms, and co-rumination, controlling for friendship stability and friendship quality, and adding a latent interaction between social anxiety and co-rumination predicting depressive symptoms. Results: Social anxiety predicted depressive symptoms, but no direct links between social anxiety and co-rumination emerged. Instead, co-rumination buffered the link between social anxiety and depressive symptoms for adolescents with higher but not lower levels of social anxiety. Conclusions: These findings indicate that co-rumination exerted a positive influence on interpersonal relationships by diminishing the influence from social anxiety on depressive symptoms over time
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