167 research outputs found

    Habitat associations of the sagebrush lizard (Sceloporus graciosus): Potential responses of an ectotherm to ponderosa pine forest restoration treatments

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    Little is known about the response of ectotherms to ponderosa pine (Pinus ponderosa) restoration treatments. The ambient body temperature of an ectotherm affects its physiology, development, and behavior. Microhabitat availability and heterogeneity are critical factors in determining which thermoregulation choices are available to a terrestrial ectotherm (Stevenson 1985). Forest restoration treatments (for example, thinning and burning) will alter herpetofauna microhabitats by decreasing tree canopy cover and allowing more sunlight penetration to the forest floor. This change could, depending on the species, have positive or negative effects on the populations of the area. We sampled microhabitat use by Sceloporus graciosus (sagebrush lizards) in northern Arizona at Grand Canyon-Parashant National Monument using standard pitfall-array sampling methodology. Univariate analyses were used to relate lizard abundance to ponderosa pine tree density, percent soil cover, percent rock cover, litter depth, and insect density. In a multivariate analysis, ponderosa pine density (negatively correlated) and bare soil cover (positively correlated) were the best predictors of lizard abundance. Restoration treatments will increase small-scale heterogeneity within S. graciosus territories by increasing accessibility into and out of sunlight. Based on the thermoregulatory demands of this species, these changes should benefit S. graciosus. However, other possible indirect effects of restoration treatments such as increases in predation on lizards (due to greater visibility), as well as changes in food availability, could negatively impact lizard populations. Future research should focus on pre- and postrestoration treatment monitoring of herpetofauna, and on the direct effects of fire on herpetofauna populations within restoration sites

    Community occupancy responses of small mammals to restoration treatments in ponderosa pine forests, northern Arizona, USA

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    In western North American conifer forests, wildfires are increasing in frequency and severity due to heavy fuel loads that have accumulated after a century of fire suppression. Forest restoration treatments (e.g., thinning and/or burning) are being designed and implemented at large spatial and temporal scales in an effort to reduce fire risk and restore forest structure and function. In ponderosa pine (Pinus ponderosa) forests, predominantly open forest structure and a frequent, low-severity fire regime constituted the evolutionary environment for wildlife that persisted for thousands of years. Small mammals are important in forest ecosystems as prey and in affecting primary production and decomposition. During 2006–2009, we trapped eight species of small mammals at 294 sites in northern Arizona and used occupancy modeling to determine community responses to thinning and habitat features. The most important covariates in predicting small mammal occupancy were understory vegetation cover, large snags, and treatment. Our analysis identified two generalist species found at relatively high occupancy rates across all sites, four open-forest species that responded positively to treatment, and two dense-forest species that responded negatively to treatment unless specific habitat features were retained. Our results indicate that all eight small mammal species can benefit from restoration treatments, particularly if aspects of their evolutionary environment (e.g., large trees, snags, woody debris) are restored. The occupancy modeling approach we used resulted in precise species-level estimates of occupancy in response to habitat attributes for a greater number of small mammal species than in other comparable studies. We recommend our approach for other studies faced with high variability and broad spatial and temporal scales in assessing impacts of treatments or habitat alteration on wildlife species. Moreover, since forest planning efforts are increasingly focusing on progressively larger treatment implementation, better and more efficiently obtained ecological information is needed to inform these efforts

    Can induced gravity isotropize Bianchi I, V, or IX Universes?

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    We analyze if Bianchi I, V, and IX models in the Induced Gravity (IG) theory can evolve to a Friedmann--Roberson--Walker (FRW) expansion due to the non--minimal coupling of gravity and the scalar field. The analytical results that we found for the Brans-Dicke (BD) theory are now applied to the IG theory which has ω1\omega \ll 1 (ω\omega being the square ratio of the Higgs to Planck mass) in a cosmological era in which the IG--potential is not significant. We find that the isotropization mechanism crucially depends on the value of ω\omega. Its smallness also permits inflationary solutions. For the Bianch V model inflation due to the Higgs potential takes place afterwads, and subsequently the spontaneous symmetry breaking (SSB) ends with an effective FRW evolution. The ordinary tests of successful cosmology are well satisfied.Comment: 24 pages, 5 figures, to be published in Phys. Rev. D1

    Volunteering and well-being : do self-esteem, optimism, and perceived control mediate the relationship?

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    Volunteers play a vital role in modern societies by boosting the labor force within both the public and private sectors. While the factors that may lead people to volunteer have been investigated in a number of studies, the means by which volunteering contributes to the well-being of such volunteers is poorly understood. It has been suggested through studies that focus on the absence of depression in volunteers that self-esteem and sense of control may be major determinants of the increased well-being reported by volunteers. This is consistent with the homeostatic model of subjective well-being, which proposes that self-esteem, optimism, and perceived control act as buffers that mediate the relationship between environmental experience and subjective well-being (SWB). Using personal well-being as a more positive measure of well-being than absence of depression, this study further explored the possible mediating role of self-esteem, optimism, and perceived control in the relationship between volunteer status and well-being. Participants (N = 1,219) completed a 97-item survey as part of the Australian Unity Wellbeing project. Variables measured included personal well-being, self-esteem, optimism, and a number of personality and psychological adjustment factors. Analyses revealed that perceived control and optimism, but not self-esteem, mediated the relationship between volunteer status and personal well-being.<br /

    No effects of ingesting or rinsing sucrose on depleted self-control performance

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    Self-control tasks appear to deplete a limited resource resulting in reduced subsequent self-control performance; a state of ego depletion. Evidence of reduced peripheral glucose by exertion of self-control, and attenuation of ego depletion by carbohydrate metabolism underpins the proposition that this macronutrient provides the energetic source of self-control. However, the demonstration of positive, non-metabolic effects on ego depletion when merely sensing carbohydrates orally contradicts this hypothesis. Recent studies have also failed to support both metabolic and non-metabolic accounts. The effects of ingesting or rinsing a carbohydrate (sucrose) and an artificially sweetened (sucralose) solution on capillary blood and interstitial glucose, and depleted self-control performance were examined in older adults. Forty, healthy, adults (50-65. years) ingested and rinsed sucrose and sucralose solutions in a 2 (method). × 2 (source), fully counterbalanced, repeated measures, crossover design. Capillary blood and interstitial glucose responses were assayed. Depleted self-control performance (induced by the Bakan visual processing task) on an attention switch task was assessed under each study condition. Ego depletion had no consistent effects on peripheral glucose levels and no significant effects of ingesting or rinsing sucrose on self-control were observed. The act of rinsing the solutions, independent of energetic content, resulted in a small, non-significant enhancement of performance on the attention switch task relative to ingesting the same solutions (RT: p= 05; accuracy: p= 09). In conclusion, a metabolic account of self-control was not supported. Whilst a positive effect of rinsing on depleted self-control performance was demonstrated, this was independent of energetic content. Findings suggest glucose is an unlikely physiological analogue for self-control resources

    Development of a pre-operative scoring system for predicting risk of post-operative paediatric cerebellar mutism syndrome

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    BACKGROUND: Despite previous identification of pre-operative clinical and radiological predictors of post-operative paediatric cerebellar mutism syndrome (CMS), a unifying pre-operative risk stratification model for use during surgical consent is currently lacking. The aim of the project is to develop a simple imaging-based pre-operative risk scoring scheme to stratify patients in terms of post-operative CMS risk. METHODS: Pre-operative radiological features were recorded for a retrospectively assembled cohort of 89 posterior fossa tumour patients from two major UK treatment centers (age 2-23yrs; gender 28 M, 61 F; diagnosis: 38 pilocytic astrocytoma, 32 medulloblastoma, 12 ependymoma, 1 high grade glioma, 1 pilomyxoid astrocytoma, 1 atypical teratoid rhabdoid tumour, 1 hemangioma, 1 neurilemmoma, 2 oligodendroglioma). Twenty-six (29%) developed post-operative CMS. Based upon results from univariate analysis and C4.5 decision tree, stepwise logistic regression was used to develop the optimal model and generate risk scores. RESULTS: Univariate analysis identified five significant risk factors and C4.5 decision tree analysis identified six predictors. Variables included in the final model are MRI primary location, bilateral middle cerebellar peduncle involvement (invasion and/or compression), dentate nucleus invasion and age at imaging >12.4 years. This model has an accuracy of 88.8% (79/89). Using risk score cut-off of 203 and 238, respectively, allowed discrimination into low (38/89, predicted CMS probability <3%), intermediate (17/89, predicted CMS probability 3-52%) and high-risk (34/89, predicted CMS probability ≥52%). CONCLUSIONS: A risk stratification model for post-operative paediatric CMS could flag patients at increased or reduced risk pre-operatively which may influence strategies for surgical treatment of cerebellar tumours. Following future testing and prospective validation, this risk scoring scheme will be proposed for use during the surgical consenting process

    Mucormycosis in Australia: Contemporary epidemiology and outcomes

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    Mucormycosis is the second most common cause of invasive mould infection and causes disease in diverse hosts, including those who are immuno-competent. We conducted a multicentre retrospective study of proven and probable cases of mucormycosis diagnosed between 2004–2012 to determine the epidemiology and outcome determinants in Australia. Seventy-four cases were identified (63 proven, 11 probable). The majority (54.1%) were caused by Rhizopus spp. Patients who sustained trauma were more likely to have non-Rhizopus infections relative to patients without trauma (OR 9.0, p 0.001, 95% CI 2.1–42.8). Haematological malignancy (48.6%), chemotherapy (42.9%), corticosteroids (52.7%), diabetes mellitus (27%) and trauma (22.9%) were the most common co-morbidities or risk factors. Rheumatological/autoimmune disorders occurred in nine (12.1%) instances. Eight (10.8%) cases had no underlying co-morbidity and were more likely to have associated trauma (7/8; 87.5% versus 10/66; 15.2%; p <0.001). Disseminated infection was common (39.2%). Apophysomyces spp. and Saksenaea spp. caused infection in immuno-competent hosts, most frequently associated with trauma and affected sites other than lung and sinuses. The 180-day mortality was 56.7%. The strongest predictors of mortality were rheumatological/autoimmune disorder (OR = 24.0, p 0.038 95% CI 1.2–481.4), haematological malignancy (OR = 7.7, p 0.001, 95% CI 2.3–25.2) and admission to intensive care unit (OR = 4.2, p 0.02, 95% CI 1.3–13.8). Most deaths occurred within one month. Thereafter we observed divergence in survival between the haematological and non-haematological populations (p 0.006). The mortality of mucormycosis remains particularly high in the immuno-compromised host. Underlying rheumatological/autoimmune disorders are a previously under-appreciated risk for infection and poor outcome

    Hematopoietic Cell Transplantation Cures Adenosine Deaminase 2 Deficiency: Report on 30 Patients.

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    Deficiency of adenosine deaminase 2 (DADA2) is an inherited inborn error of immunity, characterized by autoinflammation (recurrent fever), vasculopathy (livedo racemosa, polyarteritis nodosa, lacunar ischemic strokes, and intracranial hemorrhages), immunodeficiency, lymphoproliferation, immune cytopenias, and bone marrow failure (BMF). Tumor necrosis factor (TNF-α) blockade is the treatment of choice for the vasculopathy, but often fails to reverse refractory cytopenia. We aimed to study the outcome of hematopoietic cell transplantation (HCT) in patients with DADA2. We conducted a retrospective study on the outcome of HCT in patients with DADA2. The primary outcome was overall survival (OS). Thirty DADA2 patients from 12 countries received a total of 38 HCTs. The indications for HCT were BMF, immune cytopenia, malignancy, or immunodeficiency. Median age at HCT was 9 years (range: 2-28 years). The conditioning regimens for the final transplants were myeloablative (n = 20), reduced intensity (n = 8), or non-myeloablative (n = 2). Donors were HLA-matched related (n = 4), HLA-matched unrelated (n = 16), HLA-haploidentical (n = 2), or HLA-mismatched unrelated (n = 8). After a median follow-up of 2 years (range: 0.5-16 years), 2-year OS was 97%, and 2-year GvHD-free relapse-free survival was 73%. The hematological and immunological phenotypes resolved, and there were no new vascular events. Plasma ADA2 enzyme activity normalized in 16/17 patients tested. Six patients required more than one HCT. HCT was an effective treatment for DADA2, successfully reversing the refractory cytopenia, as well as the vasculopathy and immunodeficiency. HCT is a definitive cure for DADA2 with &gt; 95% survival
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