University of Rochester

About: University of Rochester is a education organization based out in Rochester, New York, United States. It is known for research contribution in the topics: Population & Laser. The organization has 63915 authors who have published 112762 publications receiving 5484122 citations. The organization is also known as: Rochester University.

Tadalafil Therapy for Pulmonary Arterial Hypertension

Abstract: Background— Treatment options for pulmonary arterial hypertension target the prostacyclin, endothelin, or nitric oxide pathways. Tadalafil, a phosphodiesterase type-5 inhibitor, increases cGMP, the final mediator in the nitric oxide pathway. Methods and Results— In this 16-week, double-blind, placebo-controlled study, 405 patients with pulmonary arterial hypertension (idiopathic or associated), either treatment-naive or on background therapy with the endothelin receptor antagonist bosentan, were randomized to placebo or tadalafil 2.5, 10, 20, or 40 mg orally once daily. The primary end point was the change from baseline to week 16 in the distance walked in 6 minutes. Changes in World Health Organization functional class, clinical worsening, and health-related quality of life were also assessed. Patients completing the 16-week study could enter a long-term extension study. Tadalafil increased the distance walked in 6 minutes in a dose-dependent manner; only the 40-mg dose met the prespecified level of statistical significance ( P P =0.041), incidence of clinical worsening (68% relative risk reduction; P =0.038), and health-related quality of life. The changes in World Health Organization functional class were not statistically significant. The most common treatment-related adverse events reported with tadalafil were headache, myalgia, and flushing. Conclusions— In patients with pulmonary arterial hypertension, tadalafil 40 mg was well tolerated and improved exercise capacity and quality of life measures and reduced clinical worsening.

Presidential Popularity from Truman to Johnson

Abstract: I think [my grandchildren] will be proud of two things. What I did for the Negro and seeing it through in Vietnam for all of Asia. The Negro cost me 15 points in the polls and Vietnam cost me 20.Lyndon B. JohnsonWith tenacious regularity over the last two and a half decades the Gallup Poll has posed to its cross-section samples of the American public the following query, “Do you approve or disapprove of the way (the incumbent) is handling his job as President?” The responses to this curious question form an index known as “Presidential popularity.” According to Richard Neustadt, the index is “widely taken to approximate reality” in Washington and reports about its behavior are “very widely read” there, including, the quotation above would suggest, the highest circles.Plotted over time, the index forms probably the longest continuous trend line in polling history. This study seeks to analyze the behavior of this line for the period from the beginning of the Truman administration in 1945 to the end of the Johnson administration in January 1969 during which time the popularity question was asked some 300 times.Four variables are used as predictors of a President's popularity. These include a measure of the length of time the incumbent has been in office as well as variables which attempt to estimate the influence on his rating of major international events, economic slump and war. To assess the independent impact of each of these variables as they interact in association with Presidential popularity, multiple regression analysis is used as the basic analytic technique.

Simple, fast, and practical non-blocking and blocking concurrent queue algorithms

Abstract: Drawing ideas from previous authors, we present a new non-blocking concurrent queue algorithm and a new two-lock queue algorithm in which one enqueue and one dequeue can proceed concurrently. Both algorithms are simple, fast, and practical; we were surprised not to find them in the literature. Experiments on a 12-node SGI Challenge multiprocessor indicate that the new non-blocking queue consistently outperforms the best known alternatives; it is the clear algorithm of choice for machines that provide a universal atomic primitive (e.g., compare_and_swap or load_linked/store_conditional). The two-lock concurrent queue outperforms a single lock when several processes are competing simultaneously for access; it appears to be the algorithm of choice for busy queues on machines with non-universal atomic primitives (e.g., test_and_set). Since much of the motivation for non-blocking algorithms is rooted in their immunity to large, unpredictable delays in process execution, we report experimental results both for systems with dedicated processors and for systems with several processes multiprogrammed on each processor.

Direct observation of the skyrmion Hall effect

Abstract: The well-known Hall effect describes the transverse deflection of charged particles (electrons/holes) as a result of the Lorentz force. Similarly, it is intriguing to examine if quasi-particles without an electric charge, but with a topological charge, show related transverse motion. Magnetic skyrmions with a well-defined spin texture with a unit topological charge serve as good candidates to test this hypothesis. In spite of the recent progress made on investigating magnetic skyrmions, direct observation of the skyrmion Hall effect has remained elusive. Here, by using a current-induced spin Hall spin torque, we experimentally demonstrate the skyrmion Hall effect, and the resultant skyrmion accumulation, by driving skyrmions from the creep-motion regime (where their dynamics are influenced by pinning defects) into the steady-flow-motion regime. The experimental observation of transverse transport of skyrmions due to topological charge may potentially create many exciting opportunities, such as topological selection. Experiments show that when driven by electric currents, magnetic skyrmions experience transverse motion due to their topological charge — similar to the conventional Hall effect experienced by charged particles in a perpendicular magnetic field.

Research Commentary---Digital Infrastructures: The Missing IS Research Agenda

Abstract: Since the inauguration of information systems research (ISR) two decades ago, the information systems (IS) field's attention has moved beyond administrative systems and individual tools. Millions of users log onto Facebook, download iPhone applications, and use mobile services to create decentralized work organizations. Understanding these new dynamics will necessitate the field paying attention to digital infrastructures as a category of IT artifacts. A state-of-the-art review of the literature reveals a growing interest in digital infrastructures but also confirms that the field has yet to put infrastructure at the centre of its research endeavor. To assist this shift we propose three new directions for IS research: (1) theories of the nature of digital infrastructure as a separate type of IT artifact, sui generis; (2) digital infrastructures as relational constructs shaping all traditional IS research areas; (3) paradoxes of change and control as salient IS phenomena. We conclude with suggestions for how to study longitudinal, large-scale sociotechnical phenomena while striving to remain attentive to the limitations of the traditional categories that have guided IS research.