Potential predictors of outcome in patients with tissue loss who undergo infrainguinal vein bypass grafting

AbstractPurpose: Aggressive attempts at limb salvage in patients with ischemic tissue loss are justified by favorable initial results in most patients. The identification of patients whose conditions will not benefit from attempted revascularization remains difficult. Methods: This study was designed as a retrospective review of prospectively collected clinical data. The subjects were 210 consecutive patients who underwent infrainguinal vein bypass grafting for ischemic tissue loss in the setting of an academic medical center. Bypass grafting was to the popliteal artery in 56 patients, to the infrapopliteal arteries in 131 patients, and to the pedal arteries in 23 patients. The follow-up examination was complete in 209 of 210 patients. One hundred twenty-five patients underwent blinded review of duplex scan venous mapping and arteriography to determine simplified vein and run-off scores. The outcome measures were the influence of risk factors, venous conduit, and runoff on mortality, limb loss, and graft failure at the 6-month follow-up examination. Results: One hundred seventy patients (81%) were alive and had limb salvage. Nineteen patients (9.1%) died, with need for a simultaneous inflow procedure and end-stage renal disease being most commonly associated with mortality. Thirty-three patients (15.8%) had undergone amputation: 18 after graft failure, and 15 for progressive tissue loss despite a patent graft. Amputation was significantly more common in patients with diabetes (P = .05) and with poor runoff scores (poor runoff, 44.4% vs good runoff, 7.4%; P < .01). Amputation despite a patent graft also correlated with runoff (poor runoff, 41.7% vs good runoff, 4.3%; P < .01). Twenty-five patients had graft failure without amputation, so that only 145 patients (69.4%) were alive, had limb salvage, and had a patent graft. Run-off score was the strongest predictor of outcome, with 70% of patients with poor run-off scores having death, amputation, or graft failure. Conclusion: Aggressive use of infrainguinal vein bypass grafting in patients with ischemic tissue loss results in a high rate of initial limb salvage but significant morbidity and mortality. Arteriographically determined runoff scores appear to potentially identify patients at high risk for a poor initial outcome and may provide a method of selecting patients for primary amputation. (J Vasc Surg 1999;30:427-35.

Lengthened Predelivery Stay and Antepartum Complications in Women with Depressive Symptoms During Pregnancy

Background: It is crucial to understand the timing and mechanisms behind depression's effect on peripartum stay because attempts to intervene will vary based on the time period involved. We designed this study to compare predelivery and postdelivery length of stay in women with and without elevated depressive symptoms during pregnancy. Methods: This study involved secondary data analysis of a larger study exploring antepartum depression. Each subject completed the Center for Epidemiological Studies Depression Scale (CES-D) during pregnancy at a mean of 25.8 weeks' gestation. We used time-stamped data to compare total peripartum, predelivery, and postdelivery lengths of stay in women with and without elevated depressive symptoms during pregnancy. In addition, we used a Cox proportional hazards regression model to evaluate potential mechanisms for depression's effect on length of stay. Results: The study sample included 802 pregnant women. Overall, 18% of study subjects scored >=16 on the CES-D. Bivariate analyses demonstrated a significant association between elevated depressive symptoms and longer predelivery stays (time from admission to delivery). Interaction analyses demonstrated a significant interaction effect between depressive symptoms and parity, such that depressive symptoms were significantly associated with predelivery length of stay in multiparas but not so in primiparous subjects. In a multivariate model of multiparous subjects, depression's effect on length of stay was partially influenced by sociodemographic confounders but remained significant until antepartum complications were added to the model. Conclusions: Depressive symptoms during pregnancy are significantly associated with a subsequent increase in predelivery length of stay, and this association is mediated in part by antepartum complications, even after controlling for sociodemographic factors. These longer hospital stays can present significant burdens to the patient, her family, and the healthcare system. Future studies should evaluate whether interventions for depression during pregnancy can impact this relationship among depressive symptoms during pregnancy, antepartum complications, and extensive predelivery hospitalizations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90486/1/jwh-2E2010-2E2380.pd

Unsupervised machine learning for transient discovery in deeper, wider, faster light curves

Identification of anomalous light curves within time-domain surveys is often challenging. In addition, with the growing number of wide-field surveys and the volume of data produced exceeding astronomers’ ability for manual evaluation, outlier and anomaly detection is becoming vital for transient science. We present an unsupervised method for transient discovery using a clustering technique and the ASTRONOMALY package. As proof of concept, we evaluate 85 553 min-cadenced light curves collected over two ∼1.5 h periods as part of the Deeper, Wider, Faster program, using two different telescope dithering strategies. By combining the clustering technique HDBSCAN with the isolation forest anomaly detection algorithm via the visual interface of ASTRONOMALY, we are able to rapidly isolate anomalous sources for further analysis. We successfully recover the known variable sources, across a range of catalogues from within the fields, and find a further seven uncatalogued variables and two stellar flare events, including a rarely observed ultrafast flare (∼5 min) from a likely M-dwarf

Spontaneous induction of the uniform lying helix alignment in bimesogenic liquid crystals for the flexoelectro-optic effect

Using in-plane electric fields, the electrical induction of the uniform lying helix (ULH) alignment in chiral nematic liquid crystals is reported. This process permits spontaneous induction of the ULH alignment to give an in-plane optic axis, without the need for complex processing. Flexoelectro-optic switching is subsequently obtained by holding the in-plane electrodes at a common voltage and addressing via a third, plane-parallel electrode on a second, or upper, substrate to give a field across the device in the viewing direction. For this device, in optimized bimesogenic materials, we demonstrate full intensity modulation and sub-millisecond response times at typical device temperatures. (C) 2012 American Institute of Physics. [doi:10.1063/1.3682305]11Nsciescopu

Probing the extragalactic fast transient sky at minute timescales with DECam

Searches for optical transients are usually performed with a cadence of days to weeks, optimised for supernova discovery. The optical fast transient sky is still largely unexplored, with only a few surveys to date having placed meaningful constraints on the detection of extragalactic transients evolving at sub-hour timescales. Here, we present the results of deep searches for dim, minute-timescale extragalactic fast transients using the Dark Energy Camera, a core facility of our all-wavelength and all-messenger Deeper, Wider, Faster programme. We used continuous 20s exposures to systematically probe timescales down to 1.17 minutes at magnitude limits $g > 23$ (AB), detecting hundreds of transient and variable sources. Nine candidates passed our strict criteria on duration and non-stellarity, all of which could be classified as flare stars based on deep multi-band imaging. Searches for fast radio burst and gamma-ray counterparts during simultaneous multi-facility observations yielded no counterparts to the optical transients. Also, no long-term variability was detected with pre-imaging and follow-up observations using the SkyMapper optical telescope. We place upper limits for minute-timescale fast optical transient rates for a range of depths and timescales. Finally, we demonstrate that optical $g$-band light curve behaviour alone cannot discriminate between confirmed extragalactic fast transients such as prompt GRB flashes and Galactic stellar flares.Comment: Published in MNRA

Broadband UBVRI Photometry of Horizontal-Branch and Metal-Poor Candidates from the HK and Hamburg/ESO Surveys. I

We report broadband UBV and/or BVRI CCD photometry for a total of 1857 stars in the thick-disk and halo populations of the Galaxy. The majority of our targets were selected as candidate field horizontal-branch or other A-type stars (FHB/A, N = 576), or candidate low-metallicity stars (N = 1221), from the HK and Hamburg/ESO objective-prism surveys. Similar data for a small number of additional stars from other samples are also reported. These data are being used for several purposes. In the case of the FHB/A candidates they are used to accurately separate the lower-gravity FHB stars from various higher-gravity A-type stars, a subsample that includes the so-called Blue Metal Poor stars, halo and thick-disk blue stragglers, main-sequence A-type dwarfs, and Am and Ap stars. These data are also being used to derive photometric distance estimates to high-velocity hydrogen clouds in the Galaxy and for improved measurements of the mass of the Galaxy. Photometric data for the metal-poor candidates are being used to refine estimates of stellar metallicity for objects with available medium-resolution spectroscopy, to obtain distance estimates for kinematic analyses, and to establish initial estimates of effective temperature for analysis of high-resolution spectroscopy of the stars for which this information now exists.Comment: 22 pages, including 3 figures, 5 tables, and two ascii files of full data, accepted for publication in the Astrophysical Journal (Supplements

Broadband UBVR_CI_C Photometry of Horizontal-Branch and Metal-poor Candidates from the HK and Hamburg/ESO Surveys. I.

We report broadband UBV and/or BVR_CI_C CCD photometry for a total of 1857 stars in the thick-disk and halo populations of the Galaxy. The majority of our targets were selected as candidate field horizontal-branch or other A-type stars (FHB/A, N = 576), or candidate low-metallicity stars (N = 1221), from the HK and Hamburg/ESO objective-prism surveys. Similar data for a small number of additional stars from other samples are also reported. These data are being used for several purposes. In the case of the FHB/A candidates they are used to accurately separate the lower gravity FHB stars from various higher gravity A-type stars, a subsample that includes the so-called blue metal poor stars, halo and thick-disk blue stragglers, main-sequence A-type dwarfs, and Am and Ap stars. These data are also being used to derive photometric distance estimates to high-velocity hydrogen clouds in the Galaxy and for improved measurements of the mass of the Galaxy. Photometric data for the metal-poor candidates are being used to refine estimates of stellar metallicity for objects with available medium-resolution spectroscopy, to obtain distance estimates for kinematic analyses, and to establish initial estimates of effective temperature for analysis of high-resolution spectroscopy of the stars for which this information now exists