In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery ...of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z = 0.54 elliptical galaxy in the MACS J1149.6+2223 cluster. The cluster's gravitational potential also creates multiple images of the z = 1.49 spiral supernova host galaxy, and a future appearance of the supernova elsewhere in the cluster field is expected. The magnifications and staggered arrivals of the supernova images probe the cosmic expansion rate, as well as the distribution of matter in the galaxy and cluster lenses.
Suicide prediction models have the potential to improve the identification of patients at heightened suicide risk by using predictive algorithms on large-scale data sources. Suicide prediction models ...are being developed for use across enterprise-level health care systems including the US Department of Defense, US Department of Veterans Affairs, and Kaiser Permanente.
To evaluate the diagnostic accuracy of suicide prediction models in predicting suicide and suicide attempts and to simulate the effects of implementing suicide prediction models using population-level estimates of suicide rates.
A systematic literature search was conducted in MEDLINE, PsycINFO, Embase, and the Cochrane Library to identify research evaluating the predictive accuracy of suicide prediction models in identifying patients at high risk for a suicide attempt or death by suicide. Each database was searched from inception to August 21, 2018. The search strategy included search terms for suicidal behavior, risk prediction, and predictive modeling. Reference lists of included studies were also screened. Two reviewers independently screened and evaluated eligible studies.
From a total of 7306 abstracts reviewed, 17 cohort studies met the inclusion criteria, representing 64 unique prediction models across 5 countries with more than 14 million participants. The research quality of the included studies was generally high. Global classification accuracy was good (≥0.80 in most models), while the predictive validity associated with a positive result for suicide mortality was extremely low (≤0.01 in most models). Simulations of the results suggest very low positive predictive values across a variety of population assessment characteristics.
To date, suicide prediction models produce accurate overall classification models, but their accuracy of predicting a future event is near 0. Several critical concerns remain unaddressed, precluding their readiness for clinical applications across health systems.
We used observations from the Giant Metrewave Radio Telescope to measure the atomic hydrogen gas content of 324 galaxies around the galaxy cluster Abell 370 at a redshift of z= 0.37 (a look-back time ...of ∼4 billion years). The H i 21 cm emission from these galaxies was measured by co-adding their signals using precise optical redshifts obtained with the Anglo-Australian Telescope. The average H i mass measured for all 324 galaxies is (6.6 ± 3.5) × 109 M⊙, while the average H i mass measured for the 105 optically blue galaxies is (19.0 ± 6.5) × 109 M⊙. The significant quantities of gas found around Abell 370 suggest that there has been substantial evolution in the gas content of galaxy clusters since redshift z= 0.37. The total amount of atomic hydrogen gas found around Abell 370 is up to approximately eight times more than that seen around the Coma cluster, a nearby galaxy cluster of similar size. Despite this higher gas content, Abell 370 shows the same trend as nearby clusters that galaxies close to the cluster core have lower H i gas content than galaxies further away where the galaxy density is lower. The optically blue galaxies contain the majority of the H i gas surrounding the cluster. However, there is evidence that the optically red galaxies contain appreciable quantities of H i gas within their central regions. The Abell 370 galaxies have H i mass-to-optical-light ratios similar to local galaxy samples and have the same correlation between their star formation rate and H i mass as found in the nearby galaxies. The average star formation rate derived from O ii emission and from deredshifted 1.4 GHz radio continuum for the Abell 370 galaxies also follows the correlation found in the local Universe. The large amounts of H i gas found around the cluster can easily be consumed entirely by the observed star formation rate in the galaxies over ∼4 billion years (from z= 0.37) to the present day. Abell 370 appears set to evolve into a gas-poor system similar to galaxy clusters observed in the local Universe.
Advances in artificial intelligence and machine learning have fueled growing interest in the application of predictive analytics to identify high‐risk suicidal patients. Such application will require ...the aggregation of large‐scale, sensitive patient data to help inform complex and potentially stigmatizing health care decisions. This paper provides a description of how suicide prediction is uniquely difficult by comparing it to nonmedical (weather and traffic forecasting) and medical predictions (cancer and human immunodeficiency virus risk), followed by clinical and ethical challenges presented within a risk‐benefit conceptual framework. Because the misidentification of suicide risk may be associated with unintended negative consequences, clinicians and policymakers need to carefully weigh the risks and benefits of using suicide predictive analytics across health care populations. Practical recommendations are provided to strengthen the protection of patient rights and enhance the clinical utility of suicide predictive analytics tools.
In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery ...of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z = 0.54 elliptical galaxy in the MACS J1149.6+2223 cluster. The cluster's gravitational potential also creates multiple images of the z = 1.49 spiral supernova host galaxy, and a future appearance of the supernova elsewhere in the cluster field is expected. The magnifications and staggered arrivals of the supernova images probe the cosmic expansion rate, as well as the distribution of matter in the galaxy and cluster lenses.
We present new measurements of the parallax of seven long-period (≥10 days) Milky Way (MW) Cepheid variables (SS CMa, XY Car, VY Car, VX Per, WZ Sgr, X Pup, and S Vul) using one-dimensional ...astrometric measurements from spatial scanning of Wide-Field Camera 3 on the Hubble Space Telescope (HST). The observations were obtained at ∼6 month intervals over 4 years. The distances are 1.7-3.6 kpc, with a mean precision of 45 as (signal-to-noise ratio (S/N) 10) and a best precision of 29 as (S/N = 14). The accuracy of the parallaxes is demonstrated through independent analyses of >100 reference stars. This raises to 10 the number of long-period Cepheids with significant parallax measurements, 8 obtained from this program. We also present high-precision mean F555W, F814W, and F160W magnitudes of these Cepheids, allowing a direct, zeropoint-independent comparison to >1800 extragalactic Cepheids in the hosts of 19 SNe Ia. This sample addresses two outstanding systematic uncertainties affecting prior comparisons of MW and extragalactic Cepheids used to calibrate the Hubble constant (H0): their dissimilarity of periods and photometric systems. Comparing the new parallaxes to their predicted values derived from reversing the distance ladder gives a ratio (or independent scale for H0) of 1.037 0.036, consistent with no change and inconsistent at the 3.5 level with a ratio of 0.91 needed to match the value predicted by Planck cosmic microwave background data in concert with ΛCDM. Using these data instead to augment the Riess et al. measurement of H0 improves the precision to 2.3%, yielding 73.48 1.66 km s−1 Mpc−1, and the tension with Planck + ΛCDM increases to 3.7 . The future combination of Gaia parallaxes and HST spatial scanning photometry of 50 MW Cepheids can support a <1% calibration of H0.
The amyloid beta-protein (Abeta) is believed to be the key mediator of Alzheimer's disease (AD) pathology. Abeta is most often characterized as an incidental catabolic byproduct that lacks a normal ...physiological role. However, Abeta has been shown to be a specific ligand for a number of different receptors and other molecules, transported by complex trafficking pathways, modulated in response to a variety of environmental stressors, and able to induce pro-inflammatory activities.
Here, we provide data supporting an in vivo function for Abeta as an antimicrobial peptide (AMP). Experiments used established in vitro assays to compare antimicrobial activities of Abeta and LL-37, an archetypical human AMP. Findings reveal that Abeta exerts antimicrobial activity against eight common and clinically relevant microorganisms with a potency equivalent to, and in some cases greater than, LL-37. Furthermore, we show that AD whole brain homogenates have significantly higher antimicrobial activity than aged matched non-AD samples and that AMP action correlates with tissue Abeta levels. Consistent with Abeta-mediated activity, the increased antimicrobial action was ablated by immunodepletion of AD brain homogenates with anti-Abeta antibodies.
Our findings suggest Abeta is a hitherto unrecognized AMP that may normally function in the innate immune system. This finding stands in stark contrast to current models of Abeta-mediated pathology and has important implications for ongoing and future AD treatment strategies.
ABSTRACT
Random walk models of fluvial sediment transport recognize that grains move intermittently, with short duration steps separated by rests that are comparatively long. These models are built ...upon the probability distributions of the step length and the resting time. Motivated by these models, tracer experiments have attempted to measure directly the steps and rests of sediment grains in natural streams. This paper describes results from a large tracer experiment designed to test stochastic transport models. We used passive integrated transponder (PIT) tags to label 893 coarse gravel clasts and placed them in Halfmoon Creek, a small alpine stream near Leadville, Colorado, USA. The PIT tags allow us to locate and identify tracers without picking them up or digging them out of the streambed. They also enable us to find a very high percentage of our rocks, 98% after three years and 96% after the fourth year. We use the annual tracer displacement to test two stochastic transport models, the Einstein–Hubbell–Sayre (EHS) model and the Yang–Sayre gamma‐exponential model (GEM). We find that the GEM is a better fit to the observations, particularly for slower moving tracers and suggest that the strength of the GEM is that the gamma distribution of step lengths approximates a compound Poisson distribution. Published in 2012. This article is a US Government work and is in the public domain in the USA.
PDF
