836 resultados para Sight distance.


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In this paper we conduct a number of experiments to assess the impact of typical human body movements on the signal characteristics of outdoor body-to-body communications channels using flexible patch antennas. A modified log-distance path loss model which accounts for body shadowing and signal fading due to small movements is used to model the measured data. For line of sight channels, in which both ends of the body-to-body link are stationary, the path loss exponent is close to that for free space, although the received signal is noticeably affected by involuntary or physiological-related movements of both persons. When one person moves to obstruct the direct signal path between nodes, attenuation by the person's body can be as great as 40 dB, with even greater variation observed due to fading. The effects of movements such as rotation, tilt, walking in line of sight and non-line of sight on body-to-body communications channels are also investigated in this study. © 2011 IEEE.

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There is compelling evidence to suggest that acquired sight loss negatively impacts on emotional well-being. Despite increasing recognition of the need to provide emotional support for people with sight loss, we still do not fully understand what counselling interventions help and why they help. The aim of this study was to examine the process and outcome of counselling for a 70-year-old client who had experienced complete, irreversible, post-operative sight loss in order to gain a deeper understanding of client-defined helpful aspects of therapy. A Hermeneutic Single-Case Efficacy Design study was undertaken having received ethical approval from the University's Research Ethics Committee. The client received six sessions of counselling from a vision-impaired counsellor working within a pluralistic framework. Measures were completed by the client at every session, as well as at pre-and post-counselling. All sessions were recorded and transcribed. The client also participated in pre-and post-counselling interviews. Data formed a rich case record that was analysed by a quasi-judicial enquiry team. Results suggested that this was a successful outcome case. Client-defined helpful aspects of therapy were (1) feeling understood; (2) being able to express emotions around the loss of sight; (3) finding a new identity; (4) finding ways to cope with fear, loss, dependency, and other people's perceptions; (5) exploring the possibility of a positive future without sight; (6) making sense of things; and (7) finding ways to become more socially connected. Relevant therapeutic tasks are proposed, and four key aspects of therapy are identified, which may have implications for the development of a practice model.

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The research examined the socio-emotional impact of sight loss on a sample of 18 blind and partially sighted adults from the East coast of Scotland (average age 64). The impact of sight loss in four core areas mood, self concept, social connectedness and loss was explored. Data was collected using the mental health and social functioning sub-scales of the National Eye Institute Visual Functioning Questionnaire-25 and semi-structured interviews. Data indicated that participants experienced reduced mental health and decreased social functioning as a result of sight loss. Data also showed that participants shared common socio-emotional issues during transition from sight to blindness, starting with diagnosis, coping with deterioration of sight, experiencing loss, experiencing changed perceptions of self in relation to society, experiencing others in a changed way and experiencing rehabilitation. A theoretical model describing the socio-emotional transition from sight to blindness is proposed. Implications for practice are explored.

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This study uses a discrete choice experiment (DCE) to elicit willingness to pay estimates for changes in the water quality of three rivers. As many regions the metropolitan region Berlin-Brandenburg struggles to achieve the objectives of the Water Framework Directive until 2015. A major problem is the high load of nutrients. As the region is part of two states (Länder) and the river sections are common throughout the whole region we account for the spatial context twofold. Firstly, we incorporate the distance between each respondent and all river stretches in all MNL and RPL models, and, secondly, we consider whether respondents reside in the state of Berlin or Brandenburg. The compensating variation (CV) calculated for various scenarios shows that overall people would significantly benefit from improved water quality. The CV measures, however, also reveal that not considering the spatial context would result in severely biased welfare measures. While the distance decay effect lowers CV, state residency is connected to the frequency of status quo choices and not accounting for residency would underestimate possible welfare gains in one state. Another finding is that the extent of the market varies with respect to attributes (river stretches) and attribute levels (water quality levels).

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The focus of this paper is to consider the context of social worker communication during home visits through the lens of intimacy and distance.

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Genetic analysis on populations of European ash (Fraxinus excelsior) throughout Ireland was carried out to determine the levels and patterns of genetic diversity in naturally seeded trees in ash woodlands and hedgerows, with the aim of informing conservation and replanting strategies in the face of potential loss of trees as a result of ash dieback. Samples from 33 sites across Northern Ireland and three sites in the Republic of Ireland were genotyped for eight nuclear and ten chloroplast microsatellites. Levels of diversity were high (mean A R = 10.53; mean H O = 0.709; mean H E = 0.765) and were similar to those in Great Britain and continental Europe, whilst levels of population genetic differentiation based on nuclear microsatellites were extremely low (Φ ST = 0.0131). Levels of inbreeding (mean F IS = 0.067) were significantly lower than those reported for populations from Great Britain. Fine-scale analysis of seed dispersal indicated potential for dispersal over hundreds of metres. Our results suggest that ash woodlands across Ireland could be treated as a single management unit, and thus native material from anywhere in Ireland could be used as a source for replanting. In addition, high potential for dispersal has implications for recolonization processes post-ash dieback (Chalara fraxinea) infection, and could aid in our assessment of the capacity of ash to shift its range in response to global climate change.

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Cryptotephras (tephra not visible to the naked eye) form the foundation of the tephrostratigraphic frameworks used in Europe to date and correlate widely distributed geologic, paleoenvironmental and archaeological records. Pyne-O'Donnell et al. (2012) established the potential for developing a similar crypto-tephrostratigraphy across eastern North America by identifying multiple tephra, including the White River Ash (east; WRAe), St. Helens We and East Lake, in a peat core located in Newfoundland. Following on from this work, several ongoing projects have examined additional peat cores from Michigan, New York State, Maine, Nova Scotia and Newfoundland to build a tephrostratigraphic framework for this region. Using the precedent set by recent research by Jensen et al.(in press) that correlated the Alaskan WRAe to the European cryptotephra AD860B, unknown tephras identified in this work were not necessarily assumed to be from "expected" source areas (e.g. the Cascades). Here we present several examples of the preservation of tephra layers with an intercontinental distribution (i.e. WRAe and Ksudach 1), from relatively small magnitude events (i.e. St. Helens layer T, Mono Crater), and the first example of a Mexican ash in the NE (Volcan Ceboruco, Jala pumice). There are several implications of the identification of these units. These far-travelled ashes: (1) highlight the need to consider "ultra" distal source volcanoes for unknown cryptotephra deposits,. (2) present an opportunity for physical volcanologists to examine why some eruptions have an exceptional distribution of ash that is not necessarily controlled by the magnitude of the event. (3) complicate the idea of using tephrostratigraphic frameworks to understand the frequency of eruptions towards aiding hazard planning and prediction (e.g. Swindles et al., 2011). (4) show that there is a real potential to link tropical and mid to high-latitude paleoenvironmental records. Jensen et al. (in press) Transatlantic correlation of the Alaskan White River Ash. Geology. Pyne-O'Donnell et al. (2012). High-precision ultra-distal Holocene tephrochronology in North America. Quaternary Science Reviews, 52, 6-11. Swindles et al. (2011). A 7000 yr perspective on volcanic ash clouds affecting northern Europe. Geology, 39, 887-890.

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We investigate the use of type Ic superluminous supernovae (SLSN Ic) as standardizable candles and distance indicators. Their appeal as cosmological probes stems from their remarkable peak luminosities, hot blackbody temperatures, and bright rest-frame ultraviolet emission. We present a sample of 16 published SLSN, from redshifts 0.1 to 1.2, and calculate accurate K corrections to determine uniform magnitudes in 2 synthetic rest-frame filter bandpasses with central wavelengths at 400 nm and 520 nm. At 400 nm, we find an encouragingly low scatter in their uncorrected, raw mean magnitudes with M(400) = -21.86 ± 0.35 mag for the full sample of 16 objects. We investigate the correlation between their decline rates and peak magnitude and find that the brighter events appear to decline more slowly. In a manner similar to the Phillips relation for type Ia SNe (SNe Ia), we define a ΔM 20 decline relation. This correlates peak magnitude and decline over 20 days and can reduce the scatter in standardized peak magnitudes to ±0.22 mag. We further show that M(400) appears to have a strong color dependence. Redder objects are fainter and also become redder faster. Using this peak magnitudecolor evolution relation, a surprisingly low scatter of between ±0.08 mag and ±0.13 mag can be found in peak magnitudes, depending on sample selection. However, we caution that only 8 to 10 objects currently have enough data to test this peak magnitudecolor evolution relation. We conclude that SLSN Ic are promising distance indicators in the high-redshift universe in regimes beyond those possible with SNe Ia. Although the empirical relationships are encouraging, the unknown progenitor systems, how they may evolve with redshift, and the uncertain explosion physics are of some concern. The two major measurement uncertainties are the limited numbers of low-redshift, well-studied objects available to test these relationships and internal dust extinction in the host galaxies.

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The fortuitous occurrence of a type II-Plateau (IIP) supernova, SN 2014bc, in a galaxy for which distance estimates from a number of primary distance indicators are available provides a means with which to cross-calibrate the standardised candle method (SCM) for type IIP SNe. By applying calibrations from the literature we find distance estimates in line with the most precise measurement to NGC 4258 based on the Keplerian motion of masers (7:6 ± 0:23 Mpc), albeit with significant scatter. We provide an alternative local SCM calibration by only considering type IIP SNe that have occurred in galaxies for which a Cepheid distance estimate is available. We find a considerable reduction in scatter (σ<inf>I</inf> = 0:16 mag), but note that the current sample size is limited. Applying this calibration, we estimate a distance to NGC 4258 of 7:08 ± 0:86 Mpc.

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AIMS/HYPOTHESIS: Diabetic retinopathy is a serious complication of diabetes mellitus and can lead to blindness. A genetic component, in addition to traditional risk factors, has been well described although strong genetic factors have not yet been identified. Here, we aimed to identify novel genetic risk factors for sight-threatening diabetic retinopathy using a genome-wide association study.

METHODS: Retinopathy was assessed in white Australians with type 2 diabetes mellitus. Genome-wide association analysis was conducted for comparison of cases of sight-threatening diabetic retinopathy (n = 336) with diabetic controls with no retinopathy (n = 508). Top ranking single nucleotide polymorphisms were typed in a type 2 diabetes replication cohort, a type 1 diabetes cohort and an Indian type 2 cohort. A mouse model of proliferative retinopathy was used to assess differential expression of the nearby candidate gene GRB2 by immunohistochemistry and quantitative western blot.

RESULTS: The top ranked variant was rs3805931 with p = 2.66 × 10(-7), but no association was found in the replication cohort. Only rs9896052 (p = 6.55 × 10(-5)) was associated with sight-threatening diabetic retinopathy in both the type 2 (p = 0.035) and the type 1 (p = 0.041) replication cohorts, as well as in the Indian cohort (p = 0.016). The study-wide meta-analysis reached genome-wide significance (p = 4.15 × 10(-8)). The GRB2 gene is located downstream of this variant and a mouse model of retinopathy showed increased GRB2 expression in the retina.

CONCLUSIONS/INTERPRETATION: Genetic variation near GRB2 on chromosome 17q25.1 is associated with sight-threatening diabetic retinopathy. Several genes in this region are promising candidates and in particular GRB2 is upregulated during retinal stress and neovascularisation.