Volcano collapse promoted by progressive strength reduction: new data from Mount St. Helens

Rock shear strength plays a fundamental role in volcano flank collapse, yet pertinent data from modern collapse surfaces are rare. Using samples collected from the inferred failure surface of the massive 1980 collapse of Mount St. Helens (MSH), we determined rock shear strength via laboratory tests designed to mimic conditions in the pre-collapse edifice. We observed that the 1980 failure shear surfaces formed primarily in pervasively shattered older dome rocks; failure was not localized in sloping volcanic strata or in weak, hydrothermally altered rocks. Our test results show that rock shear strength under large confining stresses is reduced ∼20% as a result of large quasi-static shear strain, as preceded the 1980 collapse of MSH. Using quasi-3D slope-stability modeling, we demonstrate that this mechanical weakening could have provoked edifice collapse, even in the absence of transiently elevated pore-fluid pressures or earthquake ground shaking. Progressive strength reduction could promote collapses at other volcanic edifices

General Purpose Data-Driven Online System Health Monitoring with Applications to Space Operations

Modern space transportation and ground support system designs are becoming increasingly sophisticated and complex. Determining the health state of these systems using traditional parameter limit checking, or model-based or rule-based methods is becoming more difficult as the number of sensors and component interactions grows. Data-driven monitoring techniques have been developed to address these issues by analyzing system operations data to automatically characterize normal system behavior. System health can be monitored by comparing real-time operating data with these nominal characterizations, providing detection of anomalous data signatures indicative of system faults, failures, or precursors of significant failures. The Inductive Monitoring System (IMS) is a general purpose, data-driven system health monitoring software tool that has been successfully applied to several aerospace applications and is under evaluation for anomaly detection in vehicle and ground equipment for next generation launch systems. After an introduction to IMS application development, we discuss these NASA online monitoring applications, including the integration of IMS with complementary model-based and rule-based methods. Although the examples presented in this paper are from space operations applications, IMS is a general-purpose health-monitoring tool that is also applicable to power generation and transmission system monitoring

Optical properties of RbMnF3:Er3

Physic

Mass Rape in Foča: The International Criminal Tribunal for the Former Yugoslavia vs. Dragoljub Kunarac

The Bosnian war witnessed the organized expulsion of Bosnian Muslims by Serbian and Bosnian Serb military forces from 1992 until 1995. As a tactic aimed at creating mono-ethnic towns from multicultural populations, rape was perpetrated against all women, but particularly Muslim women, as part of a larger plan to terrorize populations into permanently abandoning their homes. The Muslims of Foča, a township close to the border with Montenegro, were one of the first multiethnic populations to be attacked and terrorized by Bosnian Serb and Serbian forces. Dragoljub Kunarac, Radomir Kovač, and Zoran Vuković were three Bosnian Serb soldiers, among thousands, to rape and sexually enslave Muslim women in multiple camps formed over the spring and summer of 1992. With the war’s conclusion, the International Criminal Tribunal for the Former Yugoslavia set a legal precedent in the trial of Kunarac, Kovač, and Vuković as one trial in a chain of cases at the International Criminal Court for the Former Yugoslavia to advance the classifications of what sexual violence constitutes and the ways in which these crimes would be tried in international courts of law. Importantly, the Kunarac case marked the first instance in which war criminals were convicted of rape as a crime against humanity, a legal classification second only to genocide, and was the first legal proceeding to define sexual slavery as a war crime and to convict defendents of this offense as a crime against humanity. This thesis will examine the precedent set by the Kunarac Case, exhibiting first the development of the international acceptance of sex crimes as serious war crimes, and second the broadening of sexual abuse classifications written to encompass the increasing number of sexual crimes perpetrated in modern war

Glacier slip and seismicity induced by surface melt

Many of the key processes governing fast glacier flow involve interaction between a glacier and its basal hydrological system, which is hidden from direct observation. Passive seismic monitoring has shown promise as a tool for remotely monitoring basal processes, but lack of glacier-bed access prevents clear understanding of the relationships between subglacial processes and corresponding seismic emissions. Here we describe direct measurements of basal hydrology, sliding, and broadband seismicity made in a unique subglacial facility in Norway during the onset of two summer melt seasons. In the most pronounced of these episodes, rapid delivery of surface meltwater to the bed briefly enhanced basal slip following a period of elevated high-frequency seismic activity related to surface crevassing. Subsequent ground tilt derived from ultralong-period seismic signals was associated with subglacial bedrock deformation during transient pressurization of the basal hydraulic system. These signals are interpreted to represent hydraulic jacking as the supply of water to the bed exceeded the capacity of the hydraulic system. Enhanced slip terminated 2.5 h after it started, when ice-bed decoupling or increased connectivity in the basal cavity network relieved cavity overpressure. The results support theoretical models for hydraulic jacking and illustrate how melt-induced increases in speed can be short lived if cavity growth or ice-bed decoupling allows basal water more efficient drainage

Wiki or Word? Evaluating Tools for Collaborative Writing and Editing

Businesses and other organizations are relying increasingly on virtual teams to perform a range of business activities. A key challenge in utilizing virtual teams is to support collaboration among team members who are separated by distance and/or time. In this paper we use a research model based on a combination of the Technology Acceptance Model (TAM) and the Task Technology Fit (TTF) model to examine two approaches to supporting students in collaboratively creating and editing a report for an introductory course in information systems. In our study, one group of students used MS Word with Track Changes turned on combined with emailing the document among students. A second group was provided access to a wiki where they created the report. Results show that students found the Word and email combination more useful and easier to use than the wiki environment in completing the project. Further, there was no perceived difference in the effort of collaboration between the two methods. This study raises questions about the widely held belief that web-based collaboration platforms are superior to emailing documents among collaborators

Fault management for data systems

Issues related to automating the process of fault management (fault diagnosis and response) for data management systems are considered. Substantial benefits are to be gained by successful automation of this process, particularly for large, complex systems. The use of graph-based models to develop a computer assisted fault management system is advocated. The general problem is described and the motivation behind choosing graph-based models over other approaches for developing fault diagnosis computer programs is outlined. Some existing work in the area of graph-based fault diagnosis is reviewed, and a new fault management method which was developed from existing methods is offered. Our method is applied to an automatic telescope system intended as a prototype for future lunar telescope programs. Finally, an application of our method to general data management systems is described

L’ENCYCLOPÉDIE DE DIDEROT SUR INTERNET*

Le ARTEL Project de l’University of Chicago annonce la mise sur l’Internet d’une version électronique de l’Encyclopédie, ou Dictionnaire raisonné des Sciences, des Métiers et des Arts de Denis Diderot, Jean le Rond D’Alembert et al.1.Mère, en quelque sorte, de toutes les encyclopédies modernes l’Encyclopédie, cet ouvrage collectif d’une « société de gens de lettres », reste comme un monument colossal de l’Âge des Lumières. Diderot lui-même la compare tantôt à une ville avec ses rues et ses qu..