673 research outputs found

    Sub-mm counterparts to Lyman-break galaxies

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    We summarize the main results from our SCUBA survey of Lyman-break galaxies (LBGs) at z~3. Analysis of our sample of LBGs reveals a mean flux of S850=0.6±\pm0.2 mJy, while simple models of emission based on the UV properties predict a mean flux about twice as large. Known populations of LBGs are expected to contribute flux to the weak sub-mm source portion of the far-IR background, but are not likely to comprise the bright source (S850>5 mJy) end of the SCUBA-detected source count. The detection of the LBG, Westphal-MM8, at 1.9 mJy suggests that deeper observations of individual LBGs in our sample could uncover detections at similar levels, consistent with our UV-based predictions. By the same token, many sub-mm selected sources with S850<2 mJy could be LBGs. The data are also consistent with the FarIR/β\beta relation holding at z=3.Comment: 6 pages, 1 figure, contributed talk at UMass/INAOE Conference ``Deep Millimeter Surveys'

    A study of the Sunyaev-Zel'dovich increment using archival SCUBA data

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    In a search for evidence of the short wavelength increment in the Sunyaev-Zel'dovich (SZ) effect, we have analyzed archival galaxy cluster data from the Sub-millimetre Common User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope, resulting in the most complete pointed survey of clusters at 850 microns to date. SCUBA's 850 microns passband overlaps the peak of the SZ increment. The sample consists of 44 galaxy clusters in the range 0 < z < 1.3. Maps of each of the clusters have been made and sources have been extracted; as an ancillary product we generate the most thorough galaxy cluster point source list yet from SCUBA. Seventeen of these clusters are free of obvious AGN and have data deep enough to provide interesting measurements of the expected SZ signal. Specialized analysis techniques are employed to extract the SZ effect signal from these SCUBA data, including using SCUBA's short wavelength band as an atmospheric monitor and fitting the long wavelength channel to a model of the spatial distribution of each cluster's SZ effect. By explicitly excising the exact cluster centre from our analysis we demonstrate that emission from galaxies within the cluster does not contaminate our measurement. The SZ amplitudes from our measurements are consistently higher than the amplitudes inferred from low frequency measurements of the SZ decrement.Comment: 27 pages, 6 figures, replacement matches version published in MNRA

    Re-examining ethical obligations in the intensive care unit: HIV disclosure to surrogates

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    Physicians treating newly incapacitated patients often must help navigate surrogate decision-makers through a difficult course of treatment decisions, while safeguarding the patient's autonomy. We offer guidance for intensive care physicians who must frequently address the difficult questions concerning disclosure of confidential information to surrogates. Three clinical vignettes will highlight the ethical challenges to physician disclosure of a critically ill patient's HIV status. Two key distinctions are offered that influence the propriety of disclosure: first, whether HIV infection represents a 'primary cause' for the patient's critical illness; and second, whether the surrogate may be harmed by failure to disclose HIV status. This balanced consideration of the direct duties of physicians to patients, and their indirect duties to surrogates and third-party contacts, may be used as a framework for considering other ethical obligations in the intensive care unit. We also provide a tabulation of individual US state laws relevant to disclosure of HIV status

    Solid-Organ Transplantation in HIV-Infected Patients

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    Before the introduction of highly active antiretroviral therapy in the mid-1990s, transplantation centers were understandably reluctant to provide scarce solid organs for patients infected with the human immunodeficiency virus (HIV). However, because treated patients can now expect to live substantially longer than before, many will have end-stage organ disease long before they have life-threatening conditions related to HIV infection. It is therefore time for the transplantation community to readdress the safety, efficacy, and propriety of transplanting scarce organs in HIV-positive patients who need them. In this article, we provide ethical arguments for viewing transplantation in patients with HIV infection as analogous to transplantation in patients with other chronic illnesses. Accordingly, transplantation in HIV-positive patients should be initiated at major centers and should not be considered experimental. In addition, reimbursement for such procedures should be similar to that for transplantation in other patients, unless evidence accumulates that HIV-infected transplant recipients fare poorly

    Breaking the Redshift Deadlock - I: Constraining the star formation history of galaxies with sub-millimetre photometric redshifts

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    Future extragalactic sub-millimetre and millimetre surveys have the potential to provide a sensitive census of the level of obscured star formation in galaxies at all redshifts. While in general there is good agreement between the source counts from existing SCUBA (850um) and MAMBO (1.25mm) surveys of different depths and areas, it remains difficult to determine the redshift distribution and bolometric luminosities of the sub-millimetre and millimetre galaxy population. This is principally due to the ambiguity in identifying an individual sub-millimetre source with its optical, IR or radio counterpart which, in turn, prevents a confident measurement of the spectroscopic redshift. Additionally, the lack of data measuring the rest-frame FIR spectral peak of the sub-millimetre galaxies gives rise to poor constraints on their rest-frame FIR luminosities and star formation rates. In this paper we describe Monte-Carlo simulations of ground-based, balloon-borne and satellite sub-millimetre surveys that demonstrate how the rest-frame FIR-sub-millimetre spectral energy distributions (250-850um) can be used to derive photometric redshifts with an r.m.s accuracy of +/- 0.4 over the range 0 < z < 6. This opportunity to break the redshift deadlock will provide an estimate of the global star formation history for luminous optically-obscured galaxies [L(FIR) > 3 x 10^12 Lsun] with an accuracy of 20 per cent.Comment: 14 pages, 22 figures, submitted to MNRAS, replaced with accepted versio

    Evaluating the Economic Impact of Palliative and End-of-Life Care Interventions on Intensive Care Unit Utilization and Costs from the Hospital and Healthcare System Perspective.

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    Purpose of report: Understanding the impact of palliative care interventions on intensive care unit (ICU) costs and utilization is critical for demonstrating the value of palliative care. Performing these economic assessments, however, can be challenging. The purpose of this special report is to highlight and discuss important considerations when assessing ICU utilization and costs from the hospital perspective, with the goal of providing recommendations on methods to consider for future analyses. FINDINGS: ICU length of stay (LOS) and associated costs of care are common and important outcome measures, but must be analyzed properly to yield valid conclusions. There is significant variation in costs by day of stay in the ICU with only modest differences between an ICU day at the end of a stay and the first day on the acute care floor; this variation must be appropriately accounted for analytically. Furthermore, reporting direct variable costs, in addition to total ICU costs, is needed to understand short-term and long-term impact of a reduction in LOS. Importantly, incentives for the hospital to realize savings vary depending on reimbursement policies. SUMMARY: ICU utilization and costs are common outcomes in studies evaluating palliative care interventions. Accurate estimation and interpretation are key to understanding the economic implications of palliative care interventions

    A Pragmatic Trial of E-Cigarettes, Incentives, and Drugs for Smoking Cessation

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    In a trial examining five approaches to smoking cessation among over 6,000 U.S. employees, financial incentives combined with free cessation aids were more effective at getting employees to stop smoking than free cessation aids alone. Specifically, the most effective intervention (free cessation aids plus $600 in redeemable funds) helped 2.9% of participants stop smoking through six months after their target quit date; this rate jumped to 12.7% among participants who actively engaged in the trial and were more motivated to quit. For employees with access to usual care (information and a free motivational text messaging service), offering free cessation aids or electronic cigarettes (e-cigarettes) did not help them quit smoking
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