Boston University

About: Boston University is a education organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 48688 authors who have published 119622 publications receiving 6276020 citations. The organization is also known as: BU & Boston U.

How Do Self-Attributed and Implicit Motives Differ?.

Abstract: From the beginning of the work on the achievement motive (McClelland, Atkinson, Clark, & Lowell, 1953), it has been apparent that motive dispositions as coded in imaginative thought from stories written to pictures differ from motive dispositions with the same name as measured in self-reported desires or interests. The authors of the studies on achievement motivation wanted to demonstrate that the variable they had identified in fantasy functioned like an animal drive in the sense that it energized, directed, and selected behavior. In this tradition (cf. Melton, 1952) it was particularly important to show that a motivational disposition that these authors labeled n Achievement (for the need to achieve) would select behavior or facilitate learning just as hunger would facilitate a rat's learning a maze. When McClelland et al. examined a self-reported desire for achievement, they observed that it did not facilitate learning in the same way that n Achievement did and so concluded that self-reported desires do not function like motives. An early study (deCharms, Morrison, Reitman, & McClelland, 1955) showed that the two measures of achievement motivation were uncorrelated and that their behavioral correlates were different. For these reasons deCharms et al. urged that the two measures be distinguished in future research by referring to the variable identified in fantasy as n Achievement (for the need to achieve) and the self-reported desire for achievement as v Achievement (for valuing achievement).

Biased Bilayer Graphene: Semiconductor with a Gap Tunable by the Electric Field Effect

Abstract: We demonstrate that the electronic gap of a graphene bilayer can be controlled externally by applying a gate bias. From the magnetotransport data (Shubnikov-de Haas measurements of the cyclotron mass), and using a tight-binding model, we extract the value of the gap as a function of the electronic density. We show that the gap can be changed from zero to midinfrared energies by using fields of less, approximately < 1 V/nm, below the electric breakdown of SiO2. The opening of a gap is clearly seen in the quantum Hall regime.

The effects of specific medical conditions on the functional limitations of elders in the Framingham Study.

Abstract: OBJECTIVES. The purpose of this study was to identify associations between specific medical conditions in the elderly and limitations in functional tasks; to compare risks of disability across medical conditions, controlling for age, sex, and comorbidity; and to determine the proportion of disability attributable to each condition. METHODS. The subjects were 709 noninstitutionalized men and 1060 women of the Framingham Study cohort (mean age 73.7 +/- 6.3 years). Ten medical conditions were identified for study: knee osteoarthritis, hip fracture, diabetes, stroke, heart disease, intermittent claudication, congestive heart failure, chronic obstructive pulmonary disease, depressive symptomatology, and cognitive impairment. Adjusted odds ratios were calculated for dependence on human assistance in seven functional activities. RESULTS. Stroke was significantly associated with functional limitations in all seven tasks; depressive symptomatology and hip fracture were associated with limitations in five tasks; an...

The Prevention and Treatment of Missing Data in Clinical Trials

Abstract: Missing data in clinical trials can have a major effect on the validity of the inferences that can be drawn from the trial. This article reviews methods for preventing missing data and, failing that, dealing with data that are missing.

Generating representative Web workloads for network and server performance evaluation

Abstract: One role for workload generation is as a means for understanding how servers and networks respond to variation in load. This enables management and capacity planning based on current and projected usage. This paper applies a number of observations of Web server usage to create a realistic Web workload generation tool which mimics a set of real users accessing a server. The tool, called Surge (Scalable URL Reference Generator) generates references matching empirical measurements of 1) server file size distribution; 2) request size distribution; 3) relative file popularity; 4) embedded file references; 5) temporal locality of reference; and 6) idle periods of individual users. This paper reviews the essential elements required in the generation of a representative Web workload. It also addresses the technical challenges to satisfying this large set of simultaneous constraints on the properties of the reference stream, the solutions we adopted, and their associated accuracy. Finally, we present evidence that Surge exercises servers in a manner significantly different from other Web server benchmarks.