414 research outputs found

    Kinematic/Dynamic Characteristics for Visual and Kinesthetic Virtual Environments

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    Work was carried out on two topics of principal importance to current progress in virtual environment research at NASA Ames and elsewhere. The first topic was directed at maximizing the temporal dynamic response of visually presented Virtual Environments (VEs) through reorganization and optimization of system hardware and software. The final results of this portion of the work was a VE system in the Advanced Display and Spatial Perception Laboratory at NASA Ames capable of updating at 60 Hz (the maximum hardware refresh rate) with latencies approaching 30 msec. In the course of achieving this system performance, specialized hardware and software tools for measurement of VE latency and analytic models correlating update rate and latency for different system configurations were developed. The second area of activity was the preliminary development and analysis of a novel kinematic architecture for three Degree Of Freedom (DOF) haptic interfaces--devices that provide force feedback for manipulative interaction with virtual and remote environments. An invention disclosure was filed on this work and a patent application is being pursued by NASA Ames. Activities in these two areas are expanded upon below

    Surgery and adjuvant radiotherapy vs concurrent chemoradiotherapy in stage III/IV nonmetastatic squamous cell head and neck cancer: a randomised comparison

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    We compared concurrent combination chemotherapy and radiotherapy with surgery and adjuvant radiotherapy in patients with stage III/IV nonmetastatic squamous cell head and neck cancer. Patients with non-nasopharyngeal and nonsalivary resectable squamous cell head and neck cancer were randomised to receive either surgery followed by adjuvant radiotherapy (60 Gy over 30 fractions) or concurrent combination chemotherapy and radiotherapy (66 Gy in 33 fractions). Combination chemotherapy comprised two cycles of i.v. cisplatin 20 mg m− 2 day− 1 and i.v. 5-fluorouracil 1000 mg m− 2 day− 1, both to run over 96 h given on days 1 and 28 of the radiotherapy. A total of 119 patients were randomised. At a median follow-up of 6 years, there was no significant difference in the 3-year disease-free survival rate between the surgery and concurrent chemoradiotherapy (50 vs 40% respectively). The overall organ preservation rate or avoidance of surgery to primary site was 45%. Those with laryngeal/hypopharyngeal disease subsite had a higher organ-preservation rate than the rest (68 vs 30%). Combination chemotherapy and concurrent irradiation with salvage surgery was not superior to conventional surgery and postoperative radiotherapy for resectable advanced squamous cell head and neck cancer. However, this form of treatment schedule with a view to organ-preservation can be attempted especially for those with laryngeal/hypopharyngeal and possibly oropharyngeal disease subsites

    Reaching Errors Under G-Loading (and Vibration)

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    Humans show increased systematic and random errors when reaching for targets at 3.8Gx with or without added vibration

    Information Presentation: Human Research Program - Space Human Factors and Habitability, Space Human Factors Engineering Project

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    The goal of the Information Presentation Directed Research Project (DRP) is to address design questions related to the presentation of information to the crew. The major areas of work, or subtasks, within this DRP are: 1) Displays, 2) Controls, 3) Electronic Procedures and Fault Management, and 4) Human Performance Modeling. This DRP is a collaborative effort between researchers atJohnson Space Center and Ames Research Center.

    Comparison of Degradation Rates of Individual Modules Held at Maximum Power

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    States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States Government purposes. In this paper, we present a comparison of maximum power degradation rates of individual modules under out-door conditions in Golden, Colorado. Test modules in-clude single- and polycrystalline-Si (x-Si, poly-Si), amor-phous Si (a-Si, single, dual, and triple junction), CdTe, Cu-In-Ga-Se-S (CIS), and c-Si/a-Si heterostructure, from nine difference manufacturers. From monthly blocks of output power data, ratings were determined using multiple re-gressions to Performance Test Conditions (PTC). Plotting the power ratings versus time allowed degradation rates to be calculated from linear regressions. We also include a summary of module degradation rates obtained from the open literature over the past five years. Compared with the common rule-of-thumb value of 1 % per year, many modules are seen to have significantly smaller degrada-tion rates. A few modules, however, degrade significantly faster

    Development and Validation of the Behavioral Tendencies Questionnaire

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    At a fundamental level, taxonomy of behavior and behavioral tendencies can be described in terms of approach, avoid, or equivocate (i.e., neither approach nor avoid). While there are numerous theories of personality, temperament, and character, few seem to take advantage of parsimonious taxonomy. The present study sought to implement this taxonomy by creating a questionnaire based on a categorization of behavioral temperaments/tendencies first identified in Buddhist accounts over fifteen hundred years ago. Items were developed using historical and contemporary texts of the behavioral temperaments, described as “Greedy/Faithful”, “Aversive/Discerning”, and “Deluded/Speculative”. To both maintain this categorical typology and benefit from the advantageous properties of forced-choice response format (e.g., reduction of response biases), binary pairwise preferences for items were modeled using Latent Class Analysis (LCA). One sample (n1 = 394) was used to estimate the item parameters, and the second sample (n2 = 504) was used to classify the participants using the established parameters and cross-validate the classification against multiple other measures. The cross-validated measure exhibited good nomothetic span (construct-consistent relationships with related measures) that seemed to corroborate the ideas present in the original Buddhist source documents. The final 13-block questionnaire created from the best performing items (the Behavioral Tendencies Questionnaire or BTQ) is a psychometrically valid questionnaire that is historically consistent, based in behavioral tendencies, and promises practical and clinical utility particularly in settings that teach and study meditation practices such as Mindfulness Based Stress Reduction (MBSR)

    655MO Quality of life in patients with p16+ oropharyngeal cancer receiving accelerated radiotherapy (RT) with either cisplatin or cetuximab in NRG/RTOG 1016

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    Background: This phase 3 randomized non-inferiority de-escalation trial compared cetuximab (cetux) vs cisplatin (cis), concurrent with accelerated RT 70 Gy/6 weeks, in p16+ oropharyngeal cancer (OPC). Quality of life (QOL) was an important secondary endpoint. Methods: EORTC QLQ-C30/HN35 was completed at baseline, end of treatment, 3, 6, and 12 months post. The substudy aimed for 400 eligible patients. We report completion rates and compare by arm for change from baseline in each domain (0.05 two-sided alpha and MID of 10 points) using linear mixed models. Results: Consent was 91% (381/419 offered substudy); 6 protocol deviations excluded (n=375). No significant differences in patient/tumor characteristics were found by participation status. Completion rates (%) at the 5 times did not differ by arm (cis/cetux): 92/94, 74/77, 76/81, 76/81, and 73/74. The swallowing domain of HN35 (previously reported) did not differ significantly by arm. No significant difference was seen by arm for the 6-mo change from baseline on any domain. At end of RT (only), dry mouth was significantly worse for RT+cetux. At end of treatment, all domains showed statistically and clinically significant mean worsening across both arms except Emotional Functioning, Dyspnea, Diarrhea, and Teeth. Most domains returned within 10 points of baseline by 6 mo, with the following maintaining significant impairment: Senses (taste/smell), Social Eating, Opening Mouth, Dry Mouth, Sticky Saliva. At 12 mo post-treatment, worsening from baseline persisted for Senses, Dry Mouth, Sticky Saliva, and Weight Gain. Pain Killer use improved significantly from baseline to 3, 6, and 12 mo. Conclusions: Although replacing RT+cis with RT+cetux did not benefit QOL, this study has confirmed the responsiveness of EORTC QLQ-C30/HN35 to the effects of concurrent systemic/RT for OPC. Dry Mouth, Sticky Saliva, and Senses showed large, significant, and persistent impairments, and remain worthwhile targets for future de-escalation efforts. Domains related to eating (Swallowing, Appetite, Nutritional Supplements, Social Eating, Weight Loss) did not show sustained significant impairment on this instrument in this study. Clinical trial identification: NCT01302834

    Ernst Freund as Precursor of the Rational Study of Corporate Law

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    Gindis, David, Ernst Freund as Precursor of the Rational Study of Corporate Law (October 27, 2017). Journal of Institutional Economics, Forthcoming. Available at SSRN: https://ssrn.com/abstract=2905547, doi: https://dx.doi.org/10.2139/ssrn.2905547The rise of large business corporations in the late 19th century compelled many American observers to admit that the nature of the corporation had yet to be understood. Published in this context, Ernst Freund's little-known The Legal Nature of Corporations (1897) was an original attempt to come to terms with a new legal and economic reality. But it can also be described, to paraphrase Oliver Wendell Holmes, as the earliest example of the rational study of corporate law. The paper shows that Freund had the intuitions of an institutional economist, and engaged in what today would be called comparative institutional analysis. Remarkably, his argument that the corporate form secures property against insider defection and against outsiders anticipated recent work on entity shielding and capital lock-in, and can be read as an early contribution to what today would be called the theory of the firm.Peer reviewe

    Phase II study of concurrent chemoradiotherapy with capecitabine and cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck

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    We aimed to evaluate the efficacy and safety of concurrent chemoradiotherapy with capecitabine and cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). In total, 37 patients with stage III or IV SCCHN were enrolled on the study. The chemotherapy consisted of two cycles of intravenous cisplatin of 80 mg m−2 on day 1 and oral capecitabine 825 mg m−2 twice daily from day 1 to day 14 at 3-week intervals. The radiotherapy (1.8–2.0 Gy 1 fraction day−1 to a total dose of 70–70.2 Gy) was delivered to the primary tumour site and neck. The primary tumour sites were as follows: oral cavity (n=6), oropharynx (n=11), hypopharynx (n=8), larynx (n=3), nasopharynx (n=6), and paranasal sinus (n=3). After the chemoradiotherapy, 29 complete responses (78.4%) and 6 partial responses (16.2%) were confirmed. Grade 3 or 4 neutropenia occurred only in two patients, plus grade 3 febrile neutropenia was observed only in one patient. At a median follow-up duration of 19.8 months, the estimated overall survival and progression-free survival rate at 2-year was 76.8 and 57.9%, respectively. Concurrent chemoradiotherapy with capecitabine and cisplatin was found to be well tolerated and effective in patients with locally advanced SCCHN
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