Williams College

About: Williams College is a education organization based out in Williamstown, Massachusetts, United States. It is known for research contribution in the topics: Population & Politics. The organization has 2257 authors who have published 5015 publications receiving 213160 citations. The organization is also known as: Williams.

Drilling to gabbro in intact ocean crust

Abstract: Sampling an intact sequence of oceanic crust through lavas, dikes, and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid-ocean ridges, but it has been an elusive goal of scientific ocean drilling for decades. Recent drilling in the eastern Pacific Ocean in Hole 1256D reached gabbro within seismic layer 2, 1157 meters into crust formed at a superfast spreading rate. The gabbros are the crystallized melt lenses that formed beneath a mid-ocean ridge. The depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid-ocean ridges: Melt lenses occur at shallower depths at faster spreading rates. The gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas, precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by Hole 1256D.

Types for safe locking: Static race detection for Java

Abstract: This article presents a static race-detection analysis for multithreaded shared-memory programs, focusing on the Java programming language. The analysis is based on a type system that captures many common synchronization patterns. It supports classes with internal synchronization, classes that require client-side synchronization, and thread-local classes. In order to demonstrate the effectiveness of the type system, we have implemented it in a checker and applied it to over 40,000 lines of hand-annotated Java code. We found a number of race conditions in the standard Java libraries and other test programs. The checker required fewer than 20 additional type annotations per 1,000 lines of code. This article also describes two improvements that facilitate checking much larger programs: an algorithm for annotation inference and a user interface that clarifies warnings generated by the checker. These extensions have enabled us to use the checker for identifying race conditions in large-scale software systems with up to 500,000 lines of code.

The PTSD Checklist - Civilian Version: Reliability, Validity, and Factor Structure in a Nonclinical Sample

Abstract: Objective: We examined the reliability, validity, and factor structure of the posttraumatic stress diorder (PTSD) Checklist-Civilian Version (PCL-C; Blanchard, Jones-Alexander, Buckley, & Forneris, 1996) among unselected undergraduate students. Participants: Participants were 471 undergraduate students at a large university in the Eastern United States and were not preselected based on trauma history or symptom severity. Results: The PCL-C demonstrated good internal consistency and retest reliability. Compared with alternative measures of PTSD, the PCL-C showed favorable patterns of convergent and discriminant validity. In contrast to previous research using samples with known trauma exposure, we found support for both 1-factor and 2-factor models of PTSD symptoms. Conclusions: Overall, the PCL-C appears to be a valid and reliable measure of PTSD symptoms, even among nonclinical samples, and is superior to some alternative measures of PTSD. The factor structure among nonclinical samples may not reflect each of the PTSD symptom "clusters" (i.e., reexperiencing, avoidance/numbing, and hyperarousal).