193 research outputs found
Advanced LIGO's ability to detect apparent violations of the cosmic censorship conjecture and the no-hair theorem through compact binary coalescence detections
We study the ability of the advanced Laser Interferometer Gravitational-wave
Observatory (aLIGO) to detect apparent violations of the cosmic censorship
conjecture and the no-hair theorem. The cosmic censorship conjecture, which is
believed to be true in the theory of general relativity, limits the
spin-to-mass-squared ratio of a Kerr black hole. The no-hair theorem, which is
also believed to be true in the theory of general relativity, suggests a
particular value for the tidal Love number of a non-rotating black hole. Using
the Fisher matrix formalism, we examine the measurability of the spin and tidal
deformability of compact binary systems involving at least one putative black
hole. Using parameter measurement errors and correlations obtained from the
Fisher matrix, we determine the smallest detectable violation of bounds implied
by the cosmic censorship conjecture and the no-hair theorem. We examine the
effect of excluding unphysical areas of parameter space when determining the
smallest detectable apparent violations, and we examine the effect of different
post-Newtonian corrections to the amplitude of the compact binary coalescence
gravitational waveform. In addition, we perform a brief study of how the
recently calculated 3.0 pN and 3.5 pN spin-orbit corrections to the phase
affect spin and mass parameter measurability. We find that physical priors on
the symmetric mass ratio and higher harmonics in the gravitational waveform
could significantly affect the ability of aLIGO to investigate cosmic
censorship and the no-hair theorem for certain systems.Comment: 21 pages, 7 figures, 6 table
Interactive Multi-Submission Deposit Workflows for Desktop Applications
Online submission and publishing is the norm for academic researchers. With the pressure on these authors to submit their work to conferences, journals and Institutional Repositories, this leads to demands on the author to go through multiple web based interfaces, filling in forms with the same information multiple times before they can submit. At the same time, each of these services in turn will have made policy decisions on what types of format they allow and what templates the content has to conform to. The amount of work expected of the author does not adding up to the potential gain, thus most authors will only submit into the repository or publication where they foresee the most benefit. In this paper we propose a solution to this problem that embeds the workflow for multiple submissions into the desktop application of the author, most commonly Microsoft Word. We also propose extending the work done on the Microsoft Word Author Add-in tool to allow two-way negotiation between each repository and the desktop application
Tools for Dataset Lifecycle Management
With a growing demand for transparency and openness around scientific research and an emphasis on the sharing of scientific workflows and datasets, there is a similarly increasing number in the variety of client and web-based tools required to manage each stage in the lifecycle of individual datasets. Datasets are produced from a variety of instruments and computations; are analyzed and manipulated; are stored and referenced within the context of a research project; and, ideally, are archived, stored, and shared with the rest of the world. Each of these efforts, however, requires a number of user actions involving a growing number of systems and interfaces. In an effort to preserve the flexibility and autonomy of the researchers, but also to minimize the logistical effort involved, we present in this paper a partial solution approach to this problem through the integration of workflow execution, project collaboration, project-based dataset management and versioning, and long-term archiving and dissemination. This example demonstrates the orchestration of a number of existing Microsoft Research projects; however, the interaction between each uses existing web interoperability protocols and can easily support the replacement of individual architectural components with related services
Tools for Dataset Lifecycle Management
With a growing demand for transparency and openness around scientific research and an emphasis on the sharing of scientific workflows and datasets, there is a similarly increasing number in the variety of client and web-based tools required to manage each stage in the lifecycle of individual datasets. Datasets are produced from a variety of instruments and computations; are analyzed and manipulated; are stored and referenced within the context of a research project; and, ideally, are archived, stored, and shared with the rest of the world. Each of these efforts, however, requires a number of user actions involving a growing number of systems and interfaces. In an effort to preserve the flexibility and autonomy of the researchers, but also to minimize the logistical effort involved, we present in this paper a partial solution approach to this problem through the integration of workflow execution, project collaboration, project-based dataset management and versioning, and long-term archiving and dissemination. This example demonstrates the orchestration of a number of existing Microsoft Research projects; however, the interaction between each uses existing web interoperability protocols and can easily support the replacement of individual architectural components with related services
Multivariate Patterns in the Human Object-Processing Pathway Reveal a Shift from Retinotopic to Shape Curvature Representations in Lateral Occipital Areas, LO-1 and LO-2
Representations in early visual areas are organized on the basis of retinotopy, but this organizational principle appears to lose prominence in the extrastriate cortex. Nevertheless, an extrastriate region, such as the shape-selective lateral occipital cortex (LO), must still base its activation on the responses from earlier retinotopic visual areas, implying that a transition from retinotopic to “functional” organizations should exist. We hypothesized that such a transition may lie in LO-1 or LO-2, two visual areas lying between retinotopically defined V3d and functionally defined LO. Using a rapid event-related fMRI paradigm, we measured neural similarity in 12 human participants between pairs of stimuli differing along dimensions of shape exemplar and shape complexity within both retinotopically and functionally defined visual areas. These neural similarity measures were then compared with low-level and more abstract (curvature-based) measures of stimulus similarity. We found that low-level, but not abstract, stimulus measures predicted V1–V3 responses, whereas the converse was true for LO, a double dissociation. Critically, abstract stimulus measures were most predictive of responses within LO-2, akin to LO, whereas both low-level and abstract measures were predictive for responses within LO-1, perhaps indicating a transitional point between those two organizational principles. Similar transitions to abstract representations were not observed in the more ventral stream passing through V4 and VO-1/2. The transition we observed in LO-1 and LO-2 demonstrates that a more “abstracted” representation, typically considered the preserve of “category-selective” extrastriate cortex, can nevertheless emerge in retinotopic regions
Calibration Uncertainty for Advanced LIGO's First and Second Observing Runs
Calibration of the Advanced LIGO detectors is the quantification of the
detectors' response to gravitational waves. Gravitational waves incident on the
detectors cause phase shifts in the interferometer laser light which are read
out as intensity fluctuations at the detector output. Understanding this
detector response to gravitational waves is crucial to producing accurate and
precise gravitational wave strain data. Estimates of binary black hole and
neutron star parameters and tests of general relativity require well-calibrated
data, as miscalibrations will lead to biased results. We describe the method of
producing calibration uncertainty estimates for both LIGO detectors in the
first and second observing runs.Comment: 15 pages, 21 figures, LIGO DCC P160013
Impact of prior biologic use on persistence of treatment in patients with psoriatic arthritis enrolled in the US Corrona registry
Psoriatic arthritis (PsA) is a chronic condition characterized by a diverse set of symptoms, from swollen joints to nail disease to skin disease. A variety of treatment options are available, including tumor necrosis factor inhibitors (TNFis). Little is known about treatment persistence in patients with PsA who initiate TNFi therapy, with and without prior biologic use. This study assessed persistence in these subgroups of patients with PsA and identified factors associated with persistence. This retrospective study utilized data from the Corrona registry of patients with PsA-with or without prior biologic experience-who initiated TNFi therapy between October 1, 2002, and March 21, 2013. Kaplan-Meier curves estimated median time to nonpersistence (discontinuation or switch to another biologic). Cox proportional hazards models identified factors associated with TNFi nonpersistence. A total of 1241 TNFi initiations were identified: 549 by biologic-naive and 692 by biologic-experienced patients. Through 4 years of follow-up, more biologic-naive than biologic-experienced patients remained persistent. Biologic-naive patients had a greater mean time to nonpersistence compared with biologic-experienced patients: 32 vs 23 months (p = 0.0002). Moderate and high disease activities based on clinical disease activity index and disease duration were associated with persistence in both biologic-naive and biologic-experienced patients. Additionally, in the biologic-experienced patients, the number of prior medications and skin disease were associated with persistence. The majority of patients with PsA in this study were persistent with their TNFi therapy; biologic-naive patients had greater persistence compared with biologic-experienced patients. Predictors of persistence differed slightly between biologic-naive and biologic-experienced patients
Nightly treatment of primary insomnia with prolonged release melatonin for 6 months: a randomized placebo controlled trial on age and endogenous melatonin as predictors of efficacy and safety
<p>Background: Melatonin is extensively used in the USA in a non-regulated manner for sleep disorders. Prolonged release melatonin (PRM) is licensed in Europe and other countries for the short term treatment of primary insomnia in patients aged 55 years and over. However, a clear definition of the target patient population and well-controlled studies of long-term efficacy and safety are lacking. It is known that melatonin production declines with age. Some young insomnia patients also may have low melatonin levels. The study investigated whether older age or low melatonin excretion is a better predictor of response to PRM, whether the efficacy observed in short-term studies is sustained during continued treatment and the long term safety of such treatment.</p>
<p>Methods: Adult outpatients (791, aged 18-80 years) with primary insomnia, were treated with placebo (2 weeks) and then randomized, double-blind to 3 weeks with PRM or placebo nightly. PRM patients continued whereas placebo completers were re-randomized 1:1 to PRM or placebo for 26 weeks with 2 weeks of single-blind placebo run-out. Main outcome measures were sleep latency derived from a sleep diary, Pittsburgh Sleep Quality Index (PSQI), Quality of Life (World Health Organzaton-5) Clinical Global Impression of Improvement (CGI-I) and adverse effects and vital signs recorded at each visit.</p>
<p>Results: On the primary efficacy variable, sleep latency, the effects of PRM (3 weeks) in patients with low endogenous melatonin (6-sulphatoxymelatonin [6-SMT] ≤8 μg/night) regardless of age did not differ from the placebo, whereas PRM significantly reduced sleep latency compared to the placebo in elderly patients regardless of melatonin levels (-19.1 versus -1.7 min; P = 0.002). The effects on sleep latency and additional sleep and daytime parameters that improved with PRM were maintained or enhanced over the 6-month period with no signs of tolerance. Most adverse events were mild in severity with no clinically relevant differences between PRM and placebo for any safety outcome.</p>
<p>Conclusions: The results demonstrate short- and long-term efficacy and safety of PRM in elderly insomnia patients. Low melatonin production regardless of age is not useful in predicting responses to melatonin therapy in insomnia. The age cut-off for response warrants further investigation.</p>
Abnormal visual gain control and excitotoxicity in early-onset Parkinson's disease Drosophila models
The excitotoxic theory of Parkinson's disease (PD) hypothesises that a pathophysiological degeneration of dopaminergic neurons stems from neural hyperactivity at early stages of disease, leading to mitochondrial stress and cell death. Recent research has harnessed the visual system of Drosophila PD models to probe this hypothesis. Here, we investigate whether abnormal visual sensitivity and excitotoxicity occur in early-onset PD Drosophila models DJ-1Δ72, DJ1-Δ93, and PINK15. We used an electroretinogram to record steady state visually evoked potentials driven by temporal contrast stimuli. At 1 day of age, all early-onset PD mutants had a twofold increase in response amplitudes when compared to w- controls. Further, we found that excitotoxicity occurs in older early-onset PD models after increased neural demand is applied via visual stimulation. In an additional analysis, we used a linear discriminant analysis to test whether there were subtle variations in neural gain control that could be used to classify Drosophila into their correct age and genotype. The discriminant analysis was highly accurate, classifying Drosophila into their correct genotypic class at all age groups at 50-70% accuracy (20% chance baseline). Differences in cellular processes link to subtle alterations in neural network operation in young flies - all of which lead to the same pathogenic outcome. Our data are the first to demonstrate abnormal gain control and excitotoxicity in early-onset PD Drosophila mutants. We conclude that early-onset PD mutations may be linked to more sensitive neuronal signalling in prodromal animals that may cause the expression of PD symptomologies later in life
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Climate change and water in the UK: past changes and future prospects
Climate change is expected to modify rainfall, temperature and catchment hydrological responses across the world, and adapting to these water-related changes is a pressing challenge. This paper reviews the impact of anthropogenic climate change on water in the UK and looks at projections of future change. The natural variability of the UK climate makes change hard to detect; only historical increases in air temperature can be attributed to anthropogenic climate forcing, but over the last 50 years more winter rainfall has been falling in intense events. Future changes in rainfall and evapotranspiration could lead to changed flow regimes and impacts on water quality, aquatic ecosystems and water availability. Summer flows may decrease on average, but floods may become larger and more frequent. River and lake water quality may decline as a result of higher water temperatures, lower river flows and increased algal blooms in summer, and because of higher flows in the winter. In communicating this important work, researchers should pay particular attention to explaining confidence and uncertainty clearly. Much of the relevant research is either global or highly localized: decision-makers would benefit from more studies that address water and climate change at a spatial and temporal scale appropriate for the decisions they mak
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