926 research outputs found

    Thermal gradient-induced forces on geodetic reference masses for LISA

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    The low frequency sensitivity of space-borne gravitational wave observatories will depend critically on the geodetic purity of the trajectories of orbiting test masses. Fluctuations in the temperature difference across the enclosure surrounding the free-falling test mass can produce noisy forces through several processes, including the radiometric effect, radiation pressure, and outgassing. We present here a detailed experimental investigation of thermal gradient-induced forces for the LISA gravitational wave mission and the LISA Pathfinder, employing high resolution torsion pendulum measurements of the torque on a LISA-like test mass suspended inside a prototype of the LISA gravitational reference sensor that will surround the test mass in orbit. The measurement campaign, accompanied by numerical simulations of the radiometric and radiation pressure effects, allows a more accurate and representative characterization of thermal-gradient forces in the specific geometry and environment relevant to LISA free-fall. The pressure dependence of the measured torques allows clear identification of the radiometric effect, in quantitative agreement with the model developed. In the limit of zero gas pressure, the measurements are most likely dominated by outgassing, but at a low level that does not threaten the LISA sensitivity goals.Comment: 21 pages, 16 figures, submitted to Physical Review

    Patient Preferences for Treatment Outcomes in Oncology with a Focus on the Older Patient:A Systematic Review

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    SIMPLE SUMMARY: In oncology, treatment outcomes can be competing, which means that one treatment could benefit one outcome, like survival, and negatively influence another, like independence. The choice of treatment therefore depends on the patient’s preference for outcomes, which needs to be assessed explicitly. Especially in older patients, patient preferences are important. Our systematic review summarizes all studies that assessed patient preferences for various treatment outcome categories. A total of 28 studies with 4374 patients were included, of which only six studies included mostly older patients. Although quality of life was only included in half of the studies, overall quality of life (79%) was most frequently prioritized as highest or second highest, followed by overall survival (67%), progression- and disease-free survival (56%), absence of severe or persistent treatment side effects (54%), treatment response (50%), and absence of transient short-term side effects (16%). In shared decision-making, these results can be used by healthcare professionals to better tailor the information provision and treatment recommendations to the individual patient. ABSTRACT: For physicians, it is important to know which treatment outcomes are prioritized overall by older patients with cancer, since this will help them to tailor the amount of information and treatment recommendations. Older patients might prioritize other outcomes than younger patients. Our objective is to summarize which outcomes matter most to older patients with cancer. A systematic review was conducted, in which we searched Embase and Medline on 22 December 2020. Studies were eligible if they reported some form of prioritization of outcome categories relative to each other in patients with all types of cancer and if they included at least three outcome categories. Subsequently, for each study, the highest or second-highest outcome category was identified and presented in relation to the number of studies that included that outcome category. An adapted Newcastle–Ottawa Scale was used to assess the risk of bias. In total, 4374 patients were asked for their priorities in 28 studies that were included. Only six of these studies had a population with a median age above 70. Of all the studies, 79% identified quality of life as the highest or second-highest priority, followed by overall survival (67%), progression- and disease-free survival (56%), absence of severe or persistent treatment side effects (54%), and treatment response (50%). Absence of transient short-term side effects was prioritized in 16%. The studies were heterogeneous considering age, cancer type, and treatment settings. Overall, quality of life, overall survival, progression- and disease-free survival, and severe and persistent side effects of treatment are the outcomes that receive the highest priority on a group level when patients with cancer need to make trade-offs in oncologic treatment decisions

    Long-wavelength iteration scheme and scalar-tensor gravity

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    Inhomogeneous and anisotropic cosmologies are modeled withing the framework of scalar-tensor gravity theories. The inhomogeneities are calculated to third-order in the so-called long-wavelength iteration scheme. We write the solutions for general scalar coupling and discuss what happens to the third-order terms when the scalar-tensor solution approaches at first-order the general relativistic one. We work out in some detail the case of Brans-Dicke coupling and determine the conditions for which the anisotropy and inhomogeneity decay as time increases. The matter is taken to be that of perfect fluid with a barotropic equation of state.Comment: 13 pages, requires REVTeX, submitted to Phys. Rev.

    Modified Brans-Dicke theory of gravity from five-dimensional vacuum

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    We investigate, in the context of five-dimensional (5D) Brans-Dicke theory of gravity, the idea that macroscopic matter configurations can be generated from pure vacuum in five dimensions, an approach first proposed in the framework of general relativity. We show that the 5D Brans-Dicke vacuum equations when reduced to four dimensions lead to a modified version of Brans-Dicke theory in four dimensions (4D). As an application of the formalism, we obtain two five-dimensional extensions of four-dimensional O'Hanlon and Tupper vacuum solution and show that they lead two different cosmological scenarios in 4D.Comment: 9 page

    What are the mechanisms that support healthcare professionals to adopt assisted decision-making practice? A rapid realist review

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    Background The United Nations Convention on the Rights of Persons with Disabilities (UNCRPD) establishes a right to legal capacity for all people, including those with support needs. People with disabilities have a legal right to be given the appropriate supports to make informed decisions in all aspects of their lives, including health. In Ireland, the Assisted Decision-Making (Capacity) Act (2015) ratifies the Convention and has established a legal framework for Assisted Decision Making (ADM). The main provisions of the Act are not yet implemented. Codes of Practice to guide health and social care professionals are currently being developed. Internationally, concerns are expressed that ADM implementation is poorly understood. Using realist synthesis, this study aims to identify Programme Theory (PT) that will inform ADM implementation in healthcare. Methods A Rapid Realist Review using collaborative methods was chosen to appraise relevant literature and engage knowledge users from Irish health and social care. The review was led by an expert panel of relevant stakeholders that developed the research question which asks, ‘what mechanisms enable healthcare professionals to adopt ADM into practice?’ To ensure the PT was inclusive of local contextual influences, five reference panels were conducted with healthcare professionals, family carers and people with dementia. PT was refined and tested iteratively through knowledge synthesis informed by forty-seven primary studies, reference panel discussions and expert panel refinement and consensus. Results The review has developed an explanatory PT on ADM implementation in healthcare practice. The review identified four implementation domains as significant. These are Personalisation of Health & ADM Service Provision, Culture & Leadership, Environmental & Social Re-structuring and Education, Training & Enablement. Each domain is presented as an explanatory PT statement using realist convention that identifies context, mechanism and outcome configurations. Conclusions This realist review makes a unique contribution to this field. The PT can be applied by policymakers to inform intervention development and implementation strategy. It informs the imminent policy and practice developments in Ireland and has relevance for other worldwide healthcare systems dealing with similar legislative changes in line with UNCRPD

    Scalar-Tensor Models of Normal and Phantom Dark Energy

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    We consider the viability of dark energy (DE) models in the framework of the scalar-tensor theory of gravity, including the possibility to have a phantom DE at small redshifts zz as admitted by supernova luminosity-distance data. For small zz, the generic solution for these models is constructed in the form of a power series in zz without any approximation. Necessary constraints for DE to be phantom today and to cross the phantom divide line p=−ρp=-\rho at small zz are presented. Considering the Solar System constraints, we find for the post-Newtonian parameters that ÎłPN<1\gamma_{PN}<1 and ÎłPN,0≈1\gamma_{PN,0}\approx 1 for the model to be viable, and ÎČPN,0>1\beta_{PN,0}>1 (but very close to 1) if the model has a significantly phantom DE today. However, prospects to establish the phantom behaviour of DE are much better with cosmological data than with Solar System experiments. Earlier obtained results for a Λ\Lambda-dominated universe with the vanishing scalar field potential are extended to a more general DE equation of state confirming that the cosmological evolution of these models rule them out. Models of currently fantom DE which are viable for small zz can be easily constructed with a constant potential; however, they generically become singular at some higher zz. With a growing potential, viable models exist up to an arbitrary high redshift.Comment: 30 pages, 4 figures; Matches the published version containing an expanded discussion of various point

    Fair Value Hierarchy Measures: Post-Implementation Evidence on IFRS 7

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    Using a balance sheet valuation model, this study examines if information on the fair value hierarchy of on-balance sheet financial assets and financial liabilities are incorporated in the market’s valuation of companies’ equities in Singapore. The results of the study show significant associations between as-reported Level 1 and Level 2 fair value measures of financial assets and market values. However, the results are not significant for Level 3 fair value measures of financial assets and each of the three levels of fair value measures of financial liabilities. The results also show that returns are more positively associated with as-reported gains and losses from Level 1 and Level 2 fair value measures than those from Level 3 fair value measures. Overall, the evidence suggests that information on the fair value hierarchy of IFRS 7 Financial Instruments: Disclosures are used by market participants in their pricing decisions. The market however appears to place greater weights on fair value changes taken to the income statement than those taken to OCI, notwithstanding the level of the fair value measure. While the fixation with income statement measures remains a puzzle, the results are consistent with prior studies that show that investors largely ignore OCI in their pricing of shares

    Naked Singularity Formation In f(R) Gravity

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    We study the gravitational collapse of a star with barotropic equation of state p=wρp=w\rho in the context of f(R)f({\mathcal R}) theories of gravity. Utilizing the metric formalism, we rewrite the field equations as those of Brans-Dicke theory with vanishing coupling parameter. By choosing the functionality of Ricci scalar as f(R)=αRmf({\mathcal R})=\alpha{\mathcal R}^{m}, we show that for an appropriate initial value of the energy density, if α\alpha and mm satisfy certain conditions, the resulting singularity would be naked, violating the cosmic censorship conjecture. These conditions are the ratio of the mass function to the area radius of the collapsing ball, negativity of the effective pressure, and the time behavior of the Kretschmann scalar. Also, as long as parameter α\alpha obeys certain conditions, the satisfaction of the weak energy condition is guaranteed by the collapsing configuration.Comment: 15 pages, 4 figures, to appear in GR

    Self-similar cosmological solutions with a non-minimally coupled scalar field

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    We present self-similar cosmological solutions for a barotropic fluid plus scalar field with Brans-Dicke-type coupling to the spacetime curvature and an arbitrary power-law potential energy. We identify all the fixed points in the autonomous phase-plane, including a scaling solution where the fluid density scales with the scalar field's kinetic and potential energy. This is related by a conformal transformation to a scaling solution for a scalar field with exponential potential minimally coupled to the spacetime curvature, but non-minimally coupled to the barotropic fluid. Radiation is automatically decoupled from the scalar field, but energy transfer between the field and non-relativistic dark matter can lead to a change to an accelerated expansion at late times in the Einstein frame. The scalar field density can mimic a cosmological constant even for steep potentials in the strong coupling limit.Comment: 10 pages, 1 figure, revtex version to appear in Phys Rev D, references adde
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