77 research outputs found

    Cylindrical gravitational waves in expanding universes: Models for waves from compact sources

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    New boundary conditions are imposed on the familiar cylindrical gravitational wave vacuum spacetimes. The new spacetime family represents cylindrical waves in a flat expanding (Kasner) universe. Space sections are flat and nonconical where the waves have not reached and wave amplitudes fall off more rapidly than they do in Einstein-Rosen solutions, permitting a more regular null inifinity.Comment: Minor corrections to references. A note added in proo

    A Pilot Study of Neonatologists' Decision-Making Roles in Delivery Room Resuscitation Counseling for Periviable Births

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    BACKGROUND: Relatively little is known about neonatologists' roles in helping families navigate the difficult decision to attempt or withhold resuscitation for a neonate delivering at the threshold of viability. Therefore, we aimed to describe the "decision-making role" of neonatologists in simulated periviable counseling sessions. METHODS: We conducted a qualitative content analysis of audio-recorded simulation encounters and post-encounter debriefing interviews collected as part of a single-center simulation study of neonatologists' resuscitation counseling practices in the face of ruptured membranes at 23 weeks gestation. We trained standardized patients to request a recommendation if the physician presented multiple treatment options. We coded each encounter for communication behaviors, applying an adapted, previously developed coding scheme to classify physicians into four decision-making roles (informative, facilitative, collaborative, or directive). We also coded post-simulation debriefing interviews for responses to the open-ended prompt: "During this encounter, what did you feel was your role in the management decision-making process?" RESULTS: Fifteen neonatologists (33% of the division) participated in the study; audio-recorded debriefing interviews were available for 13. We observed 9 (60%) take an informative role, providing medical information only; 2 (13%) take a facilitative role, additionally eliciting the patient's values; 3 (20%) take a collaborative role, additionally engaging the patient in deliberation and providing a recommendation; and 1 (7%) take a directive role, making a treatment decision independent of the patient. Almost all (10/13, 77%) of the neonatologists described their intended role as informative. CONCLUSIONS: Neonatologists did not routinely elicit preferences, engage in deliberation, or provide treatment recommendations-even in response to requests for recommendations. These findings suggest there may be a gap between policy recommendations calling for shared decision making and actual clinical practice

    Structure and stability of Con(pyridine)m − clusters: Absence of metal inserted structures

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    A synergistic approach combining the experimental photoelectron spectroscopy and theoretical electronic structure studies is used to probe the geometrical structure and the spin magnetic moment of Con(pyridine)−m clusters. It is predicted that the ground state of Co(pyridine)− is a structure where the Co atom is inserted in a CH bond. However, the insertion is marked by a barrier of 0.33eV that is not overcome under the existing experimental conditions resulting in the formation of a structure where Co occupies a site above the pyridine plane. For Co2(pyridine)−, a ground-state structure is predicted in which the Co2 diametric moiety is inserted in one of the CH bonds, but again because of a barrier, the structure which matches the photoelectron spectrum is a higher-energy isomer in which the Co2 moiety is bonded directly to nitrogen on the pyridine ring. In all cases, the Co sites have finite magnetic moments suggesting that the complexes may provide ways of making cluster-based magnetic materials

    Potential Unintended Consequences Of Recent Shared Decision Making Policy Initiatives

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    Shared decision making (SDM)-when clinicians and patients make medical decisions together-is moving swiftly from an ethical ideal toward widespread clinical implementation affecting millions of patients through recent policy initiatives. We argue that policy initiatives to promote SDM implementation in clinical practice carry the risk of several unintended negative consequences if limitations in defining and measuring SDM are not addressed. We urge policy makers to include prespecified definitions of desired outcomes, offer guidance on the tools used to measure SDM in the multitude of contexts in which it occurs, evaluate the impact of SDM policy initiatives over time, review that impact at regular intervals, and revise SDM measurement tools as needed

    Using system dynamics for collaborative design: a case study

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    <p>Abstract</p> <p>Background</p> <p>In order to facilitate the collaborative design, system dynamics (SD) with a group modelling approach was used in the early stages of planning a new stroke unit. During six workshops a SD model was created in a multiprofessional group.</p> <p>Aim</p> <p>To explore to which extent and how the use of system dynamics contributed to the collaborative design process.</p> <p>Method</p> <p>A case study was conducted using several data sources.</p> <p>Results</p> <p>SD supported a collaborative design, by facilitating an explicit description of stroke care process, a dialogue and a joint understanding. The construction of the model obliged the group to conceptualise the stroke care and experimentation with the model gave the opportunity to reflect on care.</p> <p>Conclusion</p> <p>SD facilitated the collaborative design process and should be integrated in the early stages of the design process as a quality improvement tool.</p

    Why Did Memetics Fail? Comparative Case Study

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    Although the theory of memetics appeared highly promising at the beginning, it is no longer considered a scientific theory among contemporary evolutionary scholars. This study aims to compare the genealogy of memetics with the historically more successful gene-culture coevolution theory. This comparison is made in order to determine the constraints that emerged during the internal development of the memetics theory that could bias memeticists to work on the ontology of meme units as opposed to hypotheses testing, which was adopted by the gene-culture scholars. I trace this problem back to the diachronic development of memetics to its origin in the gene-centered anti-group-selectionist argument of George C. Williams and Richard Dawkins. The strict adoption of this argument predisposed memeticists with the a priori idea that there is no evolution without discrete units of selection, which in turn, made them dependent on the principal separation of biological and memetic fitness. This separation thus prevented memeticists from accepting an adaptationist view of culture which, on the contrary, allowed gene-culture theorists to attract more scientists to test the hypotheses, creating the historical success of the gene-culture coevolution theory

    Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

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    Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts
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