1,872 research outputs found

    Disturbance, Vegetation Co-Occurrence, and Human Intervention as Drivers of Plant Species Distributions in the Sagebrush Steppe

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    Changes in fire regimes, invasive species dynamics, human land use, and drought conditions have shifted important plant species in the Northern Great Basin (NGB)—including big sagebrush (Artemisia tridentata ssp.), conifers (e.g., Juniperus spp.) and invasive annual grasses (e.g., Bromus tectorum). Characterizing how these overlapping disturbances influence species distributions is critical for land management decision-making. Previous research has explored the individual effects of drought, wildfire, restoration, and invasive species on sagebrush steppe communities, but the specific effects of these disturbances in context with one another remain poorly understood at a landscape scale. To address this gap, I constructed multilevel conditional autoregressive (CAR) species distribution models (SDMs) to map the distributions of big sagebrush, juniper, and cheatgrass on lands managed for grazing in the NGB, both with and without a history of fire. These models illuminate the concurrent influences of species co-occurrences, drought, wildfire characteristics (e.g., fire size, time since fire, and number of fires), and restoration treatments. For all SDMs, results indicate that species co-occurrence exhibits the strongest effect—between 1.23 and 19.2 times greater than the next strongest predictor—on all species’ probability of occurrence, suggesting that vegetation co-occurrence meaningfully influences landscape-scale species distributions. In portions of the NGB both with and without historical fire, number of fires and maximum vapor pressure deficit (VPD) also exert substantial influence on the likelihood of species presence, and results indicate that restoration treatments have broadly met desired outcomes for both sagebrush and juniper Narrowing down to only areas that have previously burned, however, models do not support the efficacy of post-fire restoration. All versions of the SDMs, which rely on Bureau of Land Management-administered grazing allotments as a spatial varying intercept, also explicitly point to the differential influence of long-term management regimes on species distributions. These model predictions capture post-disturbance vegetation outcomes under changing fire, climate, and invasive species regimes and in the context of human decision-making, in turn defining a plausible ecological space as these disturbance and management processes play out into the future

    Post-stroke visual impairment: a systematic literature review of types and recovery of visual conditions

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    Aim: The aim of this literature review was to determine the reported incidence and prevalence of visual impairment due to stroke for all visual conditions including central vision loss, visual field loss, eye movement problems and visual perception problems. A further aim was to document the reported rate and extent of recovery of visual conditions post stroke. Methods: A systematic review of the literature was conducted including all languages and translations obtained. The review covered adult participants (aged 18 years or over) diagnosed with a visual impairment as a direct cause of a stroke. Studies which included mixed populations were included if over 50% of the participants had a diagnosis of stroke. We searched scholarly online resources and hand searched journals and registers of published, unpublished and ongoing trials. Search terms included a variety of MESH terms and alternatives in relation to stroke and visual conditions. The quality of the evidence was assessed using key reporting guidelines, e.g. STROBE, CONSORT. Results: Sixty-one studies (n=25,672) were included in the review. Overall prevalence of visual impairment early after stroke was estimated at 65%, ranging from 19% to 92%. Visual field loss reports ranged from 5.5% to 57%, ocular motility problems from 22% to 54%, visual inattention from 14% to 82% and reduced central vision reported in up to 70%. Recovery of visual field loss varied between 0% and 72%, with ocular motility between 7% and 92% and visual inattention between 29% and 78%. Conclusion: The current literature provides a range of estimates for prevalence of visual impairment after stroke. Visual impairment post stroke is a common problem and has significant relevance to the assessment and care these patients receive. Prospective figures regarding incidence remain unknown

    Visual Function Questionnaire as an outcome measure for homonymous hemianopia: subscales and supplementary questions, analysis from the VISION trial

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    Background: We conduct supplementary analyses of the NEI VFQ-25 data to evaluate where changes occurred within subscales of the NEI VFQ-25 leading to change in the composite scores between the three treatment arms, and evaluate the NEI VFQ-25 with and without the Neuro 10 supplement. Methods: A prospective, multicentre, parallel, single-blind, three-arm RCT of fourteen UK acute stroke units was conducted. Stroke survivors with homonymous hemianopia were recruited. Interventions included: Fresnel prisms for minimum 2 h, 5 days/week over 6-weeks (Arm a), Visual search training for minimum 30 min, 5 days/week over 6-weeks (Arm b) and standard care-information only (Arm c). Primary and secondary outcomes (including NEI VFQ-25 data) were measured at baseline, 6, 12 and 26 weeks after randomisation. Results: Eighty seven patients were recruited (69% male; mean age (SD) equal to 69 (12) years). At 26 weeks, outcomes for 24, 24 and 22 patients, respectively, were compared to baseline. NEI VFQ-25 (with and without Neuro 10) responses improved from baseline to 26 weeks with visual search training compared to Fresnel prisms and standard care. In subscale analysis, the most impacted across all treatment arms was ‘driving’ whilst the least impacted were ‘colour vision’ and ‘ocular pain’. Conclusions: Composite scores differed systematically for the NEI VFQ-25 (Neuro 10) versus NEI VFQ-25 at all time points. For subscale scores, descriptive statistics suggest clinically relevant improvement in distance activities and vision-specific dependency subscales for NEI VFQ-25 scores in the visual search treatment arm. Trial Registration: Current Controlled Trials ISRCTN05956042

    Detection of Visual Field Loss in Pituitary Disease: Peripheral Kinetic Versus Central Static.

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    Visual field assessment is an important clinical evaluation for eye disease and neurological injury. We evaluated Octopus semi-automated kinetic peripheral perimetry (SKP) and Humphrey static automated central perimetry for detection of neurological visual field loss in patients with pituitary disease. We carried out a prospective cross-sectional diagnostic accuracy study comparing Humphrey central 30-2 SITA threshold programme with a screening protocol for SKP on Octopus perimetry. Humphrey 24-2 data were extracted from 30-2 results. Results were independently graded for presence/absence of field defect plus severity of defect. Fifty patients (100 eyes) were recruited (25 males and 25 females), with mean age of 52.4 years (SD = 15.7). Order of perimeter assessment (Humphrey/Octopus first) and order of eye tested (right/left first) were randomised. The 30-2 programme detected visual field loss in 85%, the 24-2 programme in 80%, and the Octopus combined kinetic/static strategy in 100% of eyes. Peripheral visual field loss was missed by central threshold assessment. Qualitative comparison of type of visual field defect demonstrated a match between Humphrey and Octopus results in 58%, with a match for severity of defect in 50%. Tests duration was 9.34 minutes (SD = 2.02) for Humphrey 30-2 versus 10.79 minutes (SD = 4.06) for Octopus perimetry. Octopus semi-automated kinetic perimetry was found to be superior to central static testing for detection of pituitary disease-related visual field loss. Where reliant on Humphrey central static perimetry, the 30-2 programme is recommended over the 24-2 programme. Where kinetic perimetry is available, this is preferable to central static programmes for increased detection of peripheral visual field loss

    Development of Infant Reaching Strategies to Tactile Targets on the Face

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    Infant development of reaching to tactile targets on the skin has been studied little, despite its daily use during adaptive behaviors such as removing foreign stimuli or scratching an itch. We longitudinally examined the development of infant reaching strategies (from just under 2 to 11 months) approximately every other week with a vibrotactile stimulus applied to eight different locations on the face (left/right/center temple, left/right ear, left/right mouth corners, and chin). Successful reaching for the stimulus uses tactile input and proprioception to localize the target and move the hand to it. We studied the developmental progression of reaching and grasping strategies. As infants became older the likelihood of using the hand to reach to the target – versus touching the target with another body part or surface such as the upper arm or chair – increased. For trials where infants reached to the target with the hand, infants also refined their hand postures with age. As infants became older, they made fewer contacts with a closed fist or the dorsal part of the hand and more touches/grasps with the fingers or palm. Results suggest that during the first year infants become able to act more precisely on tactile targets on the face

    Teaching Cultural Competency through Global Health Education at Weill Cornell Medicine

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    Background: Educating medical students to better understand the complexities of cultural competence, the social determinants and environmental determinants of health that are important and integral components of the medical school curriculum. Methods: In 2014, Weill Cornell Medicine (WCM) implemented a new curriculum, the adoption of which provided the means to enhance an existing global health program, informally introduced in 2009, and to address the issues of cultural competency. In this article, we share WCM’s experience in building and expanding its global health curriculum. Results: A hallmark of our program is the successful collaboration between students and faculty to create a multi-disciplinary global health program that incorporates electives, clinical field placement, and collaborative research. Conclusion: Key lessons learned through our experience include the necessity for strong faculty-student collaboration, full support from the administration, and building global partnerships. Our example could be a useful guide for other medical schools seeking to establish a global health education curriculum.&nbsp

    Interventions for eye movement disorders due to acquired brain injury

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    This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: The primary objective is to assess the effects of any intervention and determine the effect of timing of any intervention in the treatment of strabismus, gaze deficits and nystagmus due to acquired brain injury in order to align visual axes in primary and/or secondary gaze positions. The secondary objectives will be to determine whether in patients with eye movement disorders due to acquired brain injury, at what time point or period, using the following interventions and comparators. •Restitutive treatment is more effective than control, placebo, alternative treatment or no treatment in improving ocular alignment and/or motility. •Substitutive treatment is more effective than control, placebo, alternative treatment or no treatment in improving ocular alignment and/or motility. •Compensatory treatment is more effective than control, placebo, alternative treatment or no treatment in improving ocular alignment and/or motility. •Pharmacological treatment is more effective than control, placebo, alternative treatment or no treatment in improving ocular alignment and/or motility

    Trace element geochemistry of K-rich impact spherules from howardites

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    The howardite-eucrite-diogenite (HED) achondrites are a group of meteorites that probably originate from the asteroid Vesta. Howardites are complex polymict breccias that sometimes contain, in addition to various rock debris, impact melt glasses which show an impressive range of compositions. In this paper we report on the geochemistry and O isotopes of a series of 6 Saharan polymict breccias (4 howardites and 2 polymict eucrites), and on the trace element abundances of high-K impact spherules found in two of them, Northwest Africa (NWA) 1664 and 1769, which are likely paired. The high-K impact spherules found in the howardites NWA 1664 and NWA 1769 display remarkable trace element patterns. Compared to eucrites or howardites, they all show prominent enrichments in Cs, Rb, K, Li and Ba, strong depletion in Na, while the REE and other refractory elements are unfractionated. These features could not have been generated during impact melting of their host howardites, nor other normal HED target materials. The involvement of Na-poor rocks, and possibly rocks of granitic composition, appears likely. Although these lithologies cannot be well constrained at present, our results demonstrate that the surface of Vesta is certainly more diverse than previously thought. Indeed, despite the large number of available HED meteorites (about 1000 different meteorites), the latter are probably not sufficient to describe the whole surface of their parent body
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