POTLIB 2001: A potential energy surface library for chemical systems

POTLIB 2001 is a computer program library of global chemical potential energy surface (PES) functions (91 functions in version 1.0) along with test data, a suite of utility programs, and a convenient user interface. The PES programs are written in ANSI standard FORTRAN77 and can be used to determine the Born-Oppenheimer potential energy of chemical systems as a function of the internal coordinates. The accompanying test data allow users to verify local implementations of this library. Finally, the utility programs permit use of this library in conjunction with a variety of chemical dynamics and chemical kinetics computer codes. Interface routines are provided for the POLYRATE and ABCRATE program packages of Truhlar and co-workers, the VENUS96 program package of Hase and co-workers, and the VARIFLEX program package of Klippenstein and co-workers; the routines in this library can also be used in conjunction with the DYNASOL program package of Zhang and co-workers. This article describes the library and the utility programs and outlines the systematic conventions used for interfaces in the computer programs contained in the library. Adherence to these conventions will allow future PESs to be compatible with this library.     

Software for high radix on-line arithmetic

High radix on-line arithmetic provides an efficient method for performing variable-precision arithmetic. It can be implemented on conventional microprocessors using sequences of three operand instructions. This paper presents software support for high radix on-line arithmetic. This software includes emulation modules for high radix operations, and a precision analysis program for setting the input and intermediate variable tolerances necessary for guaranteed result accuracy over a specified domain.     

Breaking away from the conventional 'usability lab': the Customer-Centered Design Group at Tektronix, Inc.

The conventional usability lab is primarily responsible for testing prototypes and products to determine if customers will accept a new design. Often this testing comes too late in the development cycle to allow major design or product changes to occur. In the Customer-Centered Design Group at Tektronix Labs, the usability lab is a small part of our group's involvement in the entire design life cycle of a Tektronix product. We work with design groups to bring the benefits of a usability lab to all phases of design, beginning with understanding our customer's current system and work processes to assessing the competitor's strengths and weaknesses to simulating and evaluating design alternatives. Our 'lab' is often on the road; meeting with customers where they work, working with design teams to simulate and prototype designs, and evaluating designs with our customers. To keep in touch with customers and to keep product development focused, we feel a usability group must break down the barriers inherent in a conventional testing suite. By breaking these barriers we can better determine what customers need and how these needs are addressed throughout the entire product life cycle.     

Experimental Validation of a Helicopter Autopilot Design using Model-Based PID Control

Autonomous helicopter flight provides a challenging control problem. In order to evaluate control designs, an experimental platform must be developed in order to conduct flight tests. However, the literature describing existing platforms focuses on the hardware details, while little information is given regarding software design and control algorithm implementation. This paper presents the design, implementation, and validation of an experimental helicopter platform with a primary focus on a software framework optimized for controller development. In order to validate the operation of this platform and provide a basis for comparison with more sophisticated nonlinear designs, a PID controller with feedforward gravity compensation is derived using the generally accepted small helicopter model and tested experimentally.     

Rambo: a robust, reconfigurable atomic memory service for dynamic networks

In this paper, we present Rambo, an algorithm for emulating a read/write distributed shared memory in a dynamic, rapidly changing environment. Rambo provides a highly reliable, highly available service, even as participants join, leave, and fail. In fact, the entire set of participants may change during an execution, as the initial devices depart and are replaced by a new set of devices. Even so, Rambo ensures that data stored in the distributed shared memory remains available and consistent. There are two basic techniques used by Rambo to tolerate dynamic changes. Over short intervals of time, replication suffices to provide fault-tolerance. While some devices may fail and leave, the data remains available at other replicas. Over longer intervals of time, Rambo copes with changing participants via reconfiguration, which incorporates newly joined devices while excluding devices that have departed or failed. The main novelty of Rambo lies in the combination of an efficient reconfiguration mechanism with a quorum-based replication strategy for read/write shared memory. The Rambo algorithm can tolerate a wide variety of aberrant behavior, including lost and delayed messages, participants with unsynchronized clocks, and, more generally, arbitrary asynchrony. Despite such behavior, Rambo guarantees that its data is stored consistency. We analyze the performance of Rambo during periods when the system is relatively well-behaved: messages are delivered in a timely fashion, reconfiguration is not too frequent, etc. We show that in these circumstances, read and write operations are efficient, completing in at most eight message delays.     

Computer-assisted intervention improves patient-centered diabetes care by increasing autonomy support.

Objective: To determine if a patient-centered, computer-assisted diabetes care intervention increased perceived autonomy support, perceived competence (from self-determination theory), and if these constructs mediated the effect of the intervention on ADA/NCQA recommended diabetes care outcomes. Design: A randomized controlled trial of 866 adult type 2 diabetes patients in heterogeneous primary care settings in Colorado. Main Outcome Measures: Perceived autonomy support, perceived competence, patient satisfaction, glycemic control (HbA1c), ratio of total to HDL cholesterol, diabetes distress, and depressive symptoms. Results: The computer-assisted intervention increased patient perception of autonomy support relative to a computer-based control condition ( p = .05). Change in perceived competence partially mediated the effects of increased autonomy support on the change in lipids, diabetes distress, and depressive symptoms. The construct of autonomy support was found to be separate from that of patient satisfaction. Conclusions: A patient-centered, computer-assisted intervention was effective in improving diabetes self-management outcomes, in part, because it increased patients' perception that their autonomy was supported which changed perceived competence. These findings support the self-determination model for health behavior change and the chronic care model and support the further study of the use of these technologies to motivate patients to improve their health outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mediators of telephone-based continuing care for alcohol and cocaine dependence.

A previous randomized trial with 224 alcohol and/or cocaine addicts who had completed an initial phase of treatment indicated that 12 weeks of telephone-based continuing care yielded higher abstinence rates over 24 months than did group counseling continuing care. The current study examined mediators of this treatment effect. Results suggested that self-help involvement during treatment and self-efficacy and commitment to abstinence 3 months after treatment mediated subsequent abstinence outcomes. These analyses controlled for substance use prior to the assessment of mediators. Conversely, there was no evidence that self-help beliefs or social support mediated the treatment effect. These results are consistent with a model in which treatment effects are first accounted for by changes in behavior, followed by changes in self-efficacy and in commitment to abstinence. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Stable transport of assemblies by pushing

This paper presents a method to determine whether an assembly of planar parts will stay assembled as it is pushed over a support surface. For a given pushing motion, an assembly is classified into one of three categories: (P = possible): any force necessary to preserve the assembly can be generated by the pushing contacts; (I = impossible): pushing forces cannot preserve the assembly; and (U = undecided): pushing forces may or may not be able to preserve the assembly. This classification is made based on the solution of linear constraint satisfaction problems. If the part-part and part-pusher contacts are frictionless, motions labeled P are guaranteed to preserve the assembly. The results are based on bounds on the possible support friction acting on individual parts in the face of indeterminacy in the distribution of support forces. Experimental results supporting the analysis are given.