University of Washington

About: University of Washington is a education organization based out in Seattle, Washington, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 131611 authors who have published 305578 publications receiving 17716157 citations. The organization is also known as: UW & UDub.

Allometric engineering: a causal analysis of natural selection on offspring size.

Abstract: Techniques of offspring size manipulation, "allometric engineering," were used in combination with studies of natural selection to elucidate the causal relation between egg size and offspring survival of lizards The results experimentally validate premises underlying theories of optimal egg size: fecundity selection favoring the production of large clutches of small eggs was balanced by survival selection favoring large offspring However, large hatchlings did not always have the highest survival, contrary to most theoretical expectations Optimizing selection on offspring size per se was the most common pattern Moreover, matches between average and optimal egg size were qualitative, not quantitative, perhaps reflecting known functional constraints on the production of large eggs

The impact of mergers on relaxed X-ray clusters – I. Dynamical evolution and emergent transient structures

Abstract: We report on the analysis of a suite of smoothed particle hydrodynamics simulations (incorporating cooling and star formation) of mergers involving idealized X-ray clusters whose initial conditions resemble relaxed clusters with cool compact cores observed by Chandra and XMM. The simulations sample the most-interesting, theoretically plausible, range of impact parameters and progenitor mass ratios. We find that all mergers evolve via a common progression. We illustrate this progression in the projected gas density, X-ray surface brightness, Sunyaev-Zel'dovich, temperature, and gas-entropy maps. Several different classes of transient 'cold front' like features can arise over the course of a merger. Each class is distinguished by a distinct morphological signature and physical cause. We find that all these classes are present in Chandra and XMM observations of merging systems and propose a naming scheme for these features: 'comet-like' tails, bridges, plumes, streams and edges. In none of the cases considered do the initial cool compact cores of the primary and the secondary get destroyed during the course of the mergers. Instead, the two remnant cores eventually combine to form a new core that, depending on the final mass of the remnant, can have a greater cooling efficiency than either of its progenitors. We quantify the evolving morphology of our mergers using centroid variance, power ratios and offset between the X-ray and the projected mass maps. We find that the centroid variance best captures the dynamical state of the cluster. It also provides an excellent indicator of how far the system is from virial and hydrostatic equilibrium. Placing the system at z = 0.1, we find that all easily identified observable traces of the secondary disappear from a simulated 50-ks Chandra image following the second pericentric passage. The system, however, takes an additional ∼2 Gyr to relax and virialize. Observationally, the only reliable indicator of a system in this state is the smoothness of its X-ray surface brightness isophotes, not temperature fluctuations. Temperature fluctuations at the level of AT/T ∼20 per cent, can persist in the final systems well past the point of virialization, suggesting that the existence of temperature fluctuations, in and of themselves, does not necessarily indicate a disturbed or unrelaxed system.

Performance of pile-up mitigation techniques for jets in pp collisions at √s = 8 TeV using the ATLAS detector

Abstract: The large rate of multiple simultaneous protonproton interactions, or pile-up, generated by the Large Hadron Collider in Run 1 required the development of many new techniques to mitigate the advers ...

Discounting of Monetary and Directly Consumable Rewards

Abstract: We compared temporal and probability discounting of a nonconsumable reward (money) and three directly consumable rewards (candy, soda, and beer). When rewards were delayed, monetary rewards were discounted less steeply than directly consumable rewards, all three of which were discounted at equivalent rates. When rewards were probabilistic, however, there was no difference between the discounting of monetary and directly consumable rewards. It has been reported that substance abusers discount delayed drug rewards more steeply than delayed money, but this difference may reflect special characteristics of drugs or drug abusers, or it may reflect a general property of consumable rewards. The present findings suggest that abused substances (like beer) share the properties of other directly consumable rewards, whereas delayed monetary rewards are special because they are fungible, generalized (conditioned) reinforcers.

A randomized trial of relapse prevention of depression in primary care.

Abstract: Background Despite high rates of relapse and recurrence, few primary care patients with recurrent or chronic depression are receiving continuation and maintenance-phase treatment. We hypothesized that a relapse prevention intervention would improve adherence to antidepressant medication and improve depression outcomes in high-risk patients compared with usual primary care. Methods Three hundred eighty-six patients with recurrent major depression or dysthymia who had largely recovered after 8 weeks of antidepressant treatment by their primary care physicians were randomized to a relapse prevention program (n = 194) or usual primary care (n = 192). Patients in the intervention group received 2 primary care visits with a depression specialist and 3 telephone visits over a 1-year period aimed at enhancing adherence to antidepressant medication, recognition of prodromal symptoms, monitoring of symptoms, and development of a written relapse prevention plan. Follow-up assessments were completed at 3, 6, 9, and 12 months by a telephone survey team blinded to randomization status. Results Those in the intervention group had significantly greater adherence to adequate dosage of antidepressant medication for 90 days or more within the first and second 6-month periods and were significantly more likely to refill medication prescriptions during the 12-month follow-up compared with usual care controls. Intervention patients had significantly fewer depressive symptoms, but not fewer episodes of relapse/recurrence over the 12-month follow-up period. Conclusions A relapse prevention program targeted to primary care patients with a high risk of relapse/recurrence who had largely recovered after antidepressant treatment significantly improved antidepressant adherence and depressive symptom outcomes.