Increased physical activity, physician recommendation, and senior center participation

This article employs the Andersen Behavioral Model to explore increased physical activity and participation in three types of senior center activities: physical fitness, dance/aerobic classes, and chair exercises

Fault-Injection-Based Assessment of Fail-Silence Provided by Process Duplication versus Internal Error Detection in Scientific-Based Applications

Coordinated Science Laboratory was formerly known as Control Systems Laborator

Measurement of Inclusive Spin Structure Functions of the Deuteron

We report the results of a new measurement of spin structure functions of the deuteron in the region of moderate momentum transfer ($Q^2$ = 0.27 -- 1.3 (GeV/c)$^2$) and final hadronic state mass in the nucleon resonance region ($W$ = 1.08 -- 2.0 GeV). We scattered a 2.5 GeV polarized continuous electron beam at Jefferson Lab off a dynamically polarized cryogenic solid state target ($^{15}$ND$_3$) and detected the scattered electrons with the CEBAF Large Acceptance Spectrometer (CLAS). From our data, we extract the longitudinal double spin asymmetry $A_{||}$ and the spin structure function $g_1^d$. Our data are generally in reasonable agreement with existing data from SLAC where they overlap, and they represent a substantial improvement in statistical precision. We compare our results with expectations for resonance asymmetries and extrapolated deep inelastic scaling results. Finally, we evaluate the first moment of the structure function $g_1^d$ and study its approach to both the deep inelastic limit at large $Q^2$ and to the Gerasimov-Drell-Hearn sum rule at the real photon limit ($Q^2 \to 0$). We find that the first moment varies rapidly in the $Q^2$ range of our experiment and crosses zero at $Q^2$ between 0.5 and 0.8 (GeV/c)$^2$, indicating the importance of the $\Delta$ resonance at these momentum transfers.Comment: 13 pages, 8 figures, ReVTeX 4, final version as accepted by Phys. Rev.

A Flexible Simulation Environment for Chameleon, a Software-Implemented Fault Tolerance Layer for Distributed Systems

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryNASA Langley Research CenterU of I OnlyRestricted to UIUC communit

A Process Architecture and Runtime Environment for Dependable Distributed Applications

DARPA / MURI N000914-01-1-0576National Science Foundation / NSF CCR 00-86096 ITR, NSF CCR 99-02026, and NSF ITR/AP BTeV/SBC Vanderbilt 15917-S3Ope

A Process Architecture and Runtime Environment for Dependable Distributed Applications

227 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003.This thesis introduces the theory behind (1) the construction of ARMOR processes and (2) the behavior of ARMOR processes during runtime. Reconfigurability properties of the ARMOR architecture are examined, including the ability to establish criteria that must be satisfied for a proposed reconfiguration to be considered "safe" with respect to the current ARMOR's configuration. Next, this thesis describes the SIFT environment constructed from ARMOR processes, including an in-depth case study in which the SIFT environment is used to protect spaceborne, scientific applications for the Jet Propulsion Laboratory (JPL). Error injection experiments validate the SIFT environment's ability to recover not only from user application errors, but also ARMOR errors as well. Finally, five other case studies illustrate how the ARMOR-based SIFT environment provides fault tolerance to user applications from several different domains, each requiring a different set of fault tolerance mechanisms to achieve its desired level of dependability.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Active Replication of Multithreaded Applications

This paper proposes a loose synchronization algorithm (LSA) for ensuring deterministic behavior of replicas while preserving concurrency. In contrast with techniques synchronizing replicas at the interrupt level [2], the algorithm synchronizes replica threads on state updates by intercepting mutex requests. Performance overhead is minimized by preserving concurrency in the execution of application threads (the algorithm does not interfere with the operating system scheduler, except when granting mutexes). This also contrasts with nonpreemptive, deterministic schedulers [6], [7], which limit concurrency by allowing only one physical thread to execute at a time. Although intercepting mutex requests to track the order of state updates has been proposed in the context of rollback recovery [1], it has not been applied to active replication, nor has it been demonstrated on a substantial applicatio

Loose Synchronization of Multithreaded Replicas

Although multithreading can improve performance, it is a source of nondeterminism in application behavior. Existing approaches to replicating multithreaded applications either synchronize replicas at interrupt level, at the expense of performance, or use a nonpreemptive deterministic scheduler, at the expense of concurrency. This paper presents a loose synchronization algorithm for ensuring deterministic replica behavior while preserving concurrency. The algorithm synchronizes replica threads only on state updates by enforcing an equivalent order of mutex acquisitions across replicas. 1