219 research outputs found
Effects of a physiotherapy and occupational therapy intervention on mobility and activity in care home residents: a cluster randomised controlled trial
Objective To compare the clinical effectiveness of a programme of physiotherapy and occupational therapy with standard care in care home residents who have mobility limitations and are dependent in performing activities of daily living
Dynamics of the Terra Nova Bay Polynya: The potential of multi-sensor satellite observations
Research on processes leading to formation, maintenance, and disappearance of polynyas in the Polar Regions benefits significantly from the use of different types of remote sensing data. The Sentinels of the European Space Agency (ESA), together with other satellite missions, provide a variety of data from different parts of the electromagnetic spectrum, at different spatial scales, and with different temporal resolutions. In a case study we demonstrate the advantage of merging data from different spaceborne instruments for analysing ice conditions and ice dynamics in and around the frequently occurring Terra Nova Bay Polynya (TNBP) in the Ross Sea in the Antarctic. Starting with a list of polynya parameters that are typically retrieved from satellite images, we assess the usefulness of different sensor types. On regional scales (several 100 km), passive microwave radiometers provide a view on the mutual influence of the three Ross Sea polynyas on sea ice drift and deformation patterns. Optical sensors with meter-scale resolution, on the other hand, allow very localized analyses of different polynya zones. The combination of different ranges of the electromagnetic spectrum is essential for recognition and classification of ice types and structures. Radar images together with data from thermal infrared sensors, operated at tens to hundreds of meters resolution, improve the separation of the outlet zone of the polynya from the adjacent pack ice. The direct comparison of radar and passive microwave images reveals the visibility of deformed ice zone in the latter. A sequence of radar images was employed to retrieve ice drift around the TNB, which allows analysing the temporal changes of the polynya area and the extension and structure of the outlet zone as well as ice movements and deformation that are influenced by the katabatic winds
Stability in Designer Gravity
We study the stability of designer gravity theories, in which one considers
gravity coupled to a tachyonic scalar with anti-de Sitter boundary conditions
defined by a smooth function W. We construct Hamiltonian generators of the
asymptotic symmetries using the covariant phase space method of Wald et al.and
find they differ from the spinor charges except when W=0. The positivity of the
spinor charge is used to establish a lower bound on the conserved energy of any
solution that satisfies boundary conditions for which has a global minimum.
A large class of designer gravity theories therefore have a stable ground
state, which the AdS/CFT correspondence indicates should be the lowest energy
soliton. We make progress towards proving this, by showing that minimum energy
solutions are static. The generalization of our results to designer gravity
theories in higher dimensions involving several tachyonic scalars is discussed.Comment: 29 page
A No-Go Theorem for the Consistent Quantization of Spin 3/2 Fields on General Curved Spacetimes
It is well-known that coupling a spin -field to a gravitational or
electromagnetic background leads to potential problems both in the classical
and in the quantum theory. Various solutions to these problems have been
proposed so far, which are all restricted to a limited class of backgrounds. On
the other hand, negative results for general gravitational backgrounds have
been reported only for a limited set of couplings to the background to date.
Hence, to our knowledge, a comprehensive analysis of all possible couplings to
the gravitational field and general gravitational backgrounds including
off-shell ones has not been performed so far. In this work we analyse whether
it is possible to couple a spin -field to a gravitational field in
such a way that the resulting quantum theory is consistent on arbitrary
gravitational backgrounds. We find that this is impossible as all couplings
require the background to be an Einstein spacetime for consistency. This
enforces the widespread belief that supergravity theories are the only
meaningful models which contain spin fields as in these models such
restrictions of the gravitational background appear naturally as on-shell
conditions.Comment: 8 pages, substantially abridged, results unchange
Polynya evolution at the Terra Nova Bay Antarctica – Analysis of a multi sensor time series
Coastal polynyas are open water areas in the sea ice cover. They are highly dynamical regions in the sea ice covered oceans of the Polar Regions. Their occurrence is mainly triggered by strong katabatic winds that push the ice offshore. Due to the lack of the insulating sea ice cover, polynyas have a strong impact on the local heat and energy exchange as well as on the ice production. Since the evolution of coastal polynyas is a dynamic event generating visible changes within a few hours, it is a demanding task for satellite remote sensing. The synchronised acquisition with the different sensors is of great importance for any multi sensor analysis over these dynamic regions. On the other hand it offers the chance to study various aspects of ocean - sea ice - atmosphere interactions in a relatively small area. During a recent project, funded by the Federal Ministry for Economic Affairs and Energy, we studied the potential of the Sentinel Constellation missions for Polynya research based on satellite data from present and past missions.
In the period from September to November 2014, we acquired an extensive time series of TerraSAR-X ScanSAR wide images for the Terra Nova Bay and MacKenzie Bay Polynya, Antarctica. Both polynyas are known for their regular formation, and both are small enough to fit into a ScanSAR Wide Scene of TerraSAR-X. The TerraSAR-X time series is supplemented by acquisitions from other sensors like Sentinel-1, ALOS-2, RapidEye and Landsat. The combination of these different sensors at the same day is a great opportunity to study dynamic regions such as the polynyas at hand in more detail. We will present first results on the dynamical sea ice regime around the Terra Nova Bay Polynya based on high resolution drift estimation from the acquired TerraSAR-X data and combine it with datasets from different sensors for an improved analysis of the sea ice conditions around the polynya. The results emphasises the potential of multi-sensor approaches for sea ice research
PIPERS: Preliminary Analysis of Satellite Radar Imagery from Terra Nova Bay
Satellite images provide the opportunity to differentiate different ice units in and around the Terra Nova Bay Polynya (TNBP) in the Ross Sea (Antarctica) on different spatial scales. However, at a first stage, the separation of units is usually be carried out in terms of radar signature variations, i. e. the result are “radar units” with statistically significant signature differences. In a second step, the radar units have to be linked to observations in the field in order to enable a geophysical interpretation of the stage of polynya development and the sea ice conditions around the polynya. In this specific analysis we focus on the first step. The radar imagery acquired over the TNBP comprises data from TerraSAR-X strip-map dual-polarization (HH, VV) mode, TerraSAR-X ScanSAR mode (HH-polarization), Sentinel-1 extra wide-swath mode (HH and HV polarization), and Sentinel-1 interferometric wide-swath mode (HH-polarization). Dependent on the temporal gap between image acquisitions it is possible in some cases to produce layer stacks including different imaging modes. We use different segmentation methods (such as e. g. Support Vector Machine) to arrive at a map of different radar units with only small overlaps of their radar signatures (i. e. significant discernibility). The goal is to generate a temporal sequence of radar unit maps, which in the second step in collaboration with the PIPERS team can be related to ground data gathered in the field
Pinpointing needles in giant haystacks: use of text mining to reduce impractical screening workload in extremely large scoping reviews.
In scoping reviews, boundaries of relevant evidence may be initially fuzzy, with refined conceptual understanding of interventions and their proposed mechanisms of action an intended output of the scoping process rather than its starting point. Electronic searches are therefore sensitive, often retrieving very large record sets that are impractical to screen in their entirety. This paper describes methods for applying and evaluating the use of text mining (TM) technologies to reduce impractical screening workload in reviews, using examples of two extremely large-scale scoping reviews of public health evidence (choice architecture (CA) and economic environment (EE)). Electronic searches retrieved >800,000 (CA) and >1 million (EE) records. TM technologies were used to prioritise records for manual screening. TM performance was measured prospectively. TM reduced manual screening workload by 90% (CA) and 88% (EE) compared with conventional screening (absolute reductions of ≈430 000 (CA) and ≈378 000 (EE) records). This study expands an emerging corpus of empirical evidence for the use of TM to expedite study selection in reviews. By reducing screening workload to manageable levels, TM made it possible to assemble and configure large, complex evidence bases that crossed research discipline boundaries. These methods are transferable to other scoping and systematic reviews incorporating conceptual development or explanatory dimensions
Children With Developmental Coordination Disorder Show Altered Visuomotor Control During Stair Negotiation Associated With Heightened State Anxiety
Safe stair negotiation is an everyday task that children with developmental coordination disorder (DCD) are commonly thought to struggle with. Yet, there is currently a paucity of research supporting these claims. We investigated the visuomotor control strategies underpinning stair negotiation in children with (N = 18, age = 10.50 ± 2.04 years) and without (N = 16, age = 10.94 ± 2.08 years) DCD by measuring kinematics, gaze behavior and state anxiety as they ascended and descended a staircase. A questionnaire was administered to determine parents' confidence in their child's ability to safely navigate stairs and their child's fall history (within the last year). Kinematics were measured using three-dimensional motion capture (Vicon), whilst gaze was measured using mobile eye-tracking equipment (Pupil labs). The parents of DCD children reported significantly lower confidence in their child's ability to maintain balance on the stairs and significantly more stair-related falls in the previous year compared to the parents of typically developing (TD) children. During both stair ascent and stair descent, the children with DCD took longer to ascend/descend the staircase and displayed greater handrail use, reflecting a more cautious stair negotiation strategy. No differences were observed between groups in their margin of stability, but the DCD children exhibited significantly greater variability in their foot-clearances over the step edge, which may increase the risk of a fall. For stair descent only, the DCD children reported significantly higher levels of state anxiety than the TD children and looked significantly further along the staircase during the initial entry phase, suggesting an anxiety-related response that may bias gaze toward the planning of future stepping actions over the accurate execution of an ongoing step. Taken together, our findings provide the first quantifiable evidence that (a) safe stair negotiation is a significant challenge for children with DCD, and that (b) this challenge is reflected by marked differences in their visuomotor control strategies and state anxiety levels. Whilst it is currently unclear whether these differences are contributing to the frequency of stair-related falls in children with DCD, our findings pave the way for future research to answer these important questions
Inclusion of sex chromosomes in noninvasive prenatal testing in Asia, Australia, Europe and the USA: A survey study
Objective: To examine the extent to which sex chromosomes are included in current noninvasive prenatal testing (NIPT) and the reporting practices with respect to fetal chromosomal sex and sex chromosome aberrations (SCAs), in addition to an update on the general implementation of NIPT.
Method: A questionnaire addressing the research objectives was distributed by email to fetal medicine and clinical genetics experts in Asia, Australia, Europe and the USA.
Results: Guidelines on NIPT are available in the majority of the included countries. Not all existing guidelines address reporting of fetal chromosomal sex and SCAs. In most settings, NIPT frequently includes sex chromosomes (five Australian states, China, Hong Kong, Israel, Singapore, Thailand, USA and 23 of 31 European countries). This occurs most often by default or when parents wish to know fetal sex. In most settings, a potential SCA is reported by stating the risk hereof as “low” or “high” and/or by naming the SCA. Less than 50% of all pregnant women receive NIPT according to respondents from three Australian states, China, Israel, Singapore, Thailand and 24 of 31 European countries. However, this percentage, the genomic coverage of NIPT and its application as primary or secondary screening vary by setting.
Conclusion: In most of the studied countries/states, NIPT commonly includes sex chromosomes. The reporting practices concerning fetal chromosomal sex and SCAs are diverse and most commonly not addressed by guidelines. In general, NIPT is variably implemented across countries/states
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