The Networked Common Goods Game

We introduce a new class of games called the networked common goods game (NCGG), which generalizes the well-known common goods game. We focus on a fairly general subclass of the game where each agent's utility functions are the same across all goods the agent is entitled to and satisfy certain natural properties (diminishing return and smoothness). We give a comprehensive set of technical results listed as follows. * We show the optimization problem faced by a single agent can be solved efficiently in this subclass. The discrete version of the problem is however NP-hard but admits an fully polynomial time approximation scheme (FPTAS). * We show uniqueness results of pure strategy Nash equilibrium of NCGG, and that the equilibrium is fully characterized by the structure of the network and independent of the choices and combinations of agent utility functions. * We show NCGG is a potential game, and give an implementation of best/better response Nash dynamics that lead to fast convergence to an $\epsilon$-approximate pure strategy Nash equilibrium. * Lastly, we show the price of anarchy of NCGG can be as large as $\Omega(n^{1-\epsilon})$ (for any $\epsilon>0$), which means selfish behavior in NCGG can lead to extremely inefficient social outcomes

The Association Between Phosphodiesterase-5 Inhibitors and Colorectal Cancer in a National Cohort of Patients

INTRODUCTION: To examine the association between phosphodiesterase-5 (PDE-5) inhibitor use and incidence of colorectal cancer among patients with erectile dysfunction treated in the Veterans Affairs (VA) Healthcare System. METHODS: A retrospective cohort study using the Veterans Affairs Informatics and Computing Infrastructure was conducted, with data spanning January 2001-December 2016. Patients were followed up from index until (i) the first diagnosis of colorectal cancer, (ii) death, or (iii) the end of study period. Statistical analyses evaluated demographics and baseline characteristics between cohorts (PDE-5 exposed or not) and the effect of additional dosages of each specific PDE-5 inhibitor using adjusted multivariate Cox proportional hazards models. RESULTS: A total of 221,538 patients met the study inclusion criteria, 192,691 patients in the PDE-5 cohort and 29,227 patients in the never use PDE-5 cohort. The multivariate Cox proportional hazards model results revealed that the those who had any exposure to a PDE-5 inhibitor have an 18% lower hazard of colorectal cancer (adjusted hazard ratio [HR] = 0.816, 95% confidence interval [CI] = 0.754-0.882). For each additional 100-mg dosage of sildenafil and 10-mg dosage of tadalafil, the hazard of colorectal cancer is reduced by 2.4% (adjusted HR = 0.976, 95% CI = 0.973-0.979) and 1.7% (adjusted HR = 0.983, 95% CI = 0.972-0.996), respectively. DISCUSSION: PDE-5 inhibitor usage in patients with erectile dysfunction is associated with a lower hazard of colorectal cancer compared with patients not exposed to PDE-5 inhibitors

Office-based Air-Fluid Exchange for Diabetic Post-Operative Vitreous Cavity Hemorrhage

Post-operative vitreous cavity hemorrhage (POVCH) is observed in 6-75% of eyes undergoing pars plana vitrectomy (PPV) for proliferative diabetic retinopathy (PDR). We describe our technique for office-based Air fluid exchange (AFX) in the treatment of POVCH. Sixteen eyes (15 patients) with PDR and POVCH undergoing office-based AFX between January 2006 and November 2016 were retrospectively identified. The pre- and post- procedure visual acuity (VA) and complications were compared between eyes with and without traction retinal detachment (TRD). Medicare charges for office-based AFX versus PPV were also analyzed. Mean age at the time of AFX was 55.31 (± 8.02) years. Nine eyes (56.25%) had TRD prior to PPV and 11 eyes (68.75%) were pseudophakic. The improvements in mean (± standard deviation [SD]) logMAR VA at the last postoperative visit (3 - 8 months) were 1.38 (± 0.99), 0.82 (± 0.91) and 2.09 (± 0.53) in all eyes, TRD eyes and non-TRD eyes, respectively. Complications included cataract progression, hypotony, and recurrence of TRD and ghost cell glaucoma. The total cost of outpatient AFX was $1,409.59 less than that of PPV. Office-based AFX is a cost-effective alternative treatment for non-clearing diabetic POVCH with an acceptable risk profile

Macromolecular interactions during gelatinisation and retrogradation in starch-whey systems as studied by rapid visco-analyser

Gelatinisation and retrogradation of starch-whey mixtures were studied in water (pH 7) using the Rapid Visco-Analyser (RVA). The starch:whey ratios ranged from 0:100 - 100:0. Wheat starch, and whey protein concentrate (about 80% solids basis) and isolate (about 96% solids basis) were used. Mixtures with whey isolates were generally more viscous than those with whey concentrates, and this was attributed to fewer non-protein milk components in the former. Whey protein concentrates and isolates reduced the peak, trough and final viscosities of the mixtures, but the breakdown and setback ratios of the mixtures were increased. The gelatinisation temperature increased with whey substitutions indicating that whey protein delayed starch gelatinisation. The temperature of fastest viscosity development decreased as the amount of whey was increased. Whey protein isolate generally exercised a lesser effect than the concentrate. At between 40 - 50% whey substitutions, the dominant phase changed from starch to protein irrespective of the source of the whey protein. An additive law poorly defined selected RVA parameters. Both macromolecules interacted to define the viscosity of the mixture, and an exponential model predicted the viscosity better than the additive law. The results obtained in this study are discussed to assist the understanding of extrusion processing of starch-whey systems as models for whey-fortified snack and ready-to-eat foods. Copyright ©2006 The Berkeley Electronic Press. All rights reserved

Gravitational Lensing Magnification and Time Delay Statistics for Distant Supernovae

Strong gravitational lensing of distant supernovae (SNe), particularly Type Ia's, has some exploitable properties not available when other sorts of cosmologically distant sources are lensed. One such property is that the ``standard candle'' nature of the SN at peak brightness allows a direct determination of the lensing magnification factor for each well observed image. Another is that the duration of an SN event is of the same order as the differential time delays between the various lens images. The comparable time scales of the photometric event and the time delay invite a variety of applications, including high precision measurements of the delay and the targeting of especially interesting phases of the explosion for intensive observation when they appear in trailing images. As an initial exploration of these possibilities we present calculations of SN lensing statistics in a ``concordance cosmology''. We emphasize magnification and time delay effects. Plausible SN surveys, such as the proposed SNAP space mission, would discover several to some tens of strongly lensed SNe Ia per year, and at least a few of these will be at redshifts well beyond those that would be accessible via unlensed events. The total number of such anomalously high redshift SNe Ia will be a useful test of high redshift star formation models. SN surveys of finite duration will, of course, miss the appearance of some images; we quantify this selection bias. Finally, we investigate how well the appearance of trailing images can be predicted based on various amounts of available information on the lensing event. Knowledge of the magnification factor for the leading image makes it possible to predict the appearance of a trailing image relatively accurately if the lens redshift is also known. (Abridged)Comment: 11 pages, 9 figures, emulateapj5, accepted for publication in Ap

Office-based Air-Fluid Exchange for Diabetic Post-Operative Vitreous Cavity Hemorrhage

Post-operative vitreous cavity hemorrhage (POVCH) is observed in 6-75% of eyes undergoing pars plana vitrectomy (PPV) for proliferative diabetic retinopathy (PDR). We describe our technique for office-based Air fluid exchange (AFX) in the treatment of POVCH. Sixteen eyes (15 patients) with PDR and POVCH undergoing office-based AFX between January 2006 and November 2016 were retrospectively identified. The pre- and post- procedure visual acuity (VA) and complications were compared between eyes with and without traction retinal detachment (TRD). Medicare charges for office-based AFX versus PPV were also analyzed. Mean age at the time of AFX was 55.31 (± 8.02) years. Nine eyes (56.25%) had TRD prior to PPV and 11 eyes (68.75%) were pseudophakic. The improvements in mean (± standard deviation [SD]) logMAR VA at the last postoperative visit (3 - 8 months) were 1.38 (± 0.99), 0.82 (± 0.91) and 2.09 (± 0.53) in all eyes, TRD eyes and non-TRD eyes, respectively. Complications included cataract progression, hypotony, and recurrence of TRD and ghost cell glaucoma. The total cost of outpatient AFX was $1,409.59 less than that of PPV. Office-based AFX is a cost-effective alternative treatment for non-clearing diabetic POVCH with an acceptable risk profile

Supernova Shock Breakout from a Red Supergiant

Massive stars undergo a violent death when the supply of nuclear fuel in their cores is exhausted, resulting in a catastrophic "core-collapse" supernova. Such events are usually only detected at least a few days after the star has exploded. Observations of the supernova SNLS-04D2dc with the Galaxy Evolution Explorer space telescope reveal a radiative precursor from the supernova shock before the shock reached the surface of the star and show the initial expansion of the star at the beginning of the explosion. Theoretical models of the ultraviolet light curve confirm that the progenitor was a red supergiant, as expected for this type of supernova. These observations provide a way to probe the physics of core-collapse supernovae and the internal structures of their progenitor starsComment: Science, in press. 32 pages, 7 figure