35 research outputs found

    Formation Control Using Vehicle Operational Envelopes and Behavior-Based Dual-Mode Model Predictive Control

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    This thesis presents a control framework for formation control. Given an initial desired trajectory, a framework is presented to generate trajectories for each vehicle within the formation. When combined with an operational envelope, a designated area for each vehicle to maneuver, for each vehicle the multi-vehicle formation control problem can be redefined into a single vehicle problem. A single vehicle framework is presented to track the respective trajectory when possible, or stay near it when it passes through previously unknown obstacles. Arc-based motions are used to rapidly produce desirable robot controls while a trajectory tracking motion is used to ensure that the vehicle tracks the trajectory when it is obstacle free. The resulting formation control framework is illustrated through a real-time simulation with trajectories passing through obstacles. The simulated robot is able to seamlessly balance tracking with obstacle avoidance

    SPARE PARTS: SMALL ARMS PROLIFERATION AND THE DILEMMA OF GOVERNANCE, AUTHORITY, AND FOREIGN MILITARY ASSISTANCE

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    This thesis examines the international state-directed arms trade in South Asia following WWII, and describes how attempts to limit the arms flow into the region were subverted by less constrained suppliers and by the superpowers themselves. Donor states distributed surplus items to less industrialized states, who eagerly accepted modern weapons that they could not produce domestically. Small arms are of special interest because of their very low cost; high production volume; low skill requirements for use; and the ease of distribution compared to major weapons systems. The South Asian states examined here pursued their own regional security agendas rather than conform to the Cold War paradigm of donor states. This demonstrated the failure of arms transfers as a diplomatic tool. It also resulted in a decline of civilian governance, the increased primacy of military authority, and the creation of conditions for enduring insecurity rather than security

    The Effect of LIFT on Life Effectiveness and Locus of Control

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    The purpose of this study is to measure the effects of the Leadership Inspiration Facilitation Team (LIFT) program on the life effectiveness and locus of control of a group of sixth grade students at Schultz Middle School. The participants consisted of 36 sixth grade students, ages 10 to 12 years, from a single public middle school. The participants attended a two-day summer adventure-based ROPES camp. The Review of Personal Effectiveness and Locus of Control (ROPELOC) instrument was administered at the beginning (pre-test), the end (post-test), and six months later (follow-up). The twelve domains of life effectiveness have been identified, including active involvement, cooperative teamwork, leadership ability, open thinking, quality seeking, self confidence, self efficacy, social effectiveness, stress management, time efficiency, coping with change, and overall effectiveness. Two domains of locus of control were identified: external and internal. Composite ROPELOC, subscale, and gender data were all analyzed using t-tests of independent samples. The analysis showed no significant improvement in participants? composite ROPELOC score between the pre, post, and follow-up. However, there was an increase between the pre and post, although the increase was not at a significant level. Significant increases in participants? scores were found in three of the 14 ROPELOC subscales: cooperative teamwork, coping with change, and external locus of control. Significance for cooperative teamwork was found between the pre-test and post-test. Significance for coping with change and external locus of control was found between the pre-test and follow-up, as well as between the post-test and follow-up using a significance of .05. Gender was found to have made no difference in composite ROPELOC scores. Participants in the LIFT summer program have increased self-perceptions of life effectiveness at the immediate conclusion of the program. The degree of significance has yet to be determined, and the length of significance is still in question. Researchers maintain that positive youth development is a complex myriad of interventions. Positive youth development has taken a proactive shift to promote healthy development outcomes for all youth, in addition to reducing long-term negative outcomes of at-risk youth and has emerged into its own as an independent field of study. In addition, positive youth development is resulting from the combination of several factors that lead to the development of more comprehensive models and the development of programs which address multiple behaviors and that involve families and community

    Minding the Terrazzo Gap between Athletes and Nonathletes: Representativeness, Integration, and Academic Performance at the U.S. Air Force Academy

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    The tension between focusing on collegiate athletic or academic performance has persisted for decades. A recent study finds that recruited athletes in college athletic programs underperform academically, earning lower grades than predicted. It postulates that increased representativeness and integration efforts will enhance the academic value of college athletes’ experience. The U.S. Air Force Academy system presents a natural experiment of whether such efforts can affect student-athlete academic performance. In this setting, we find that student-athletes perform comparably to nonathletes after controlling for predicted academic performance

    Mirizzi syndrome associated with hepatic artery pseudoaneurysm: a case report.

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    INTRODUCTION: This is the first case report of Mirizzi syndrome associated with hepatic artery pseudoaneurysm. CASE PRESENTATION: A 54-year-old man presented with painful obstructive jaundice and weight loss. Computed tomography showed a hilar mass in the liver. Following an episode of haemobilia, angiography demonstrated a pseudoaneurysm of a branch of the right hepatic artery that was embolised. At surgery, a gallstone causing Mirizzi type II syndrome was found to be responsible for the biliary obstruction and a necrotic inflammatory mass and haematoma were found to be extending into the liver. The mass was debrided and drained, the obstructing stones removed and the bile duct drained with a t-tube. The patient made a full recovery. CONCLUSION: This case highlights another situation where there may be difficulty in differentiating Mirizzi syndrome from biliary tract cancer.Published versio

    The Empirical Foundations of Telemedicine Interventions for Chronic Disease Management

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    The telemedicine intervention in chronic disease management promises to involve patients in their own care, provides continuous monitoring by their healthcare providers, identifies early symptoms, and responds promptly to exacerbations in their illnesses. This review set out to establish the evidence from the available literature on the impact of telemedicine for the management of three chronic diseases: congestive heart failure, stroke, and chronic obstructive pulmonary disease. By design, the review focuses on a limited set of representative chronic diseases because of their current and increasing importance relative to their prevalence, associated morbidity, mortality, and cost. Furthermore, these three diseases are amenable to timely interventions and secondary prevention through telemonitoring. The preponderance of evidence from studies using rigorous research methods points to beneficial results from telemonitoring in its various manifestations, albeit with a few exceptions. Generally, the benefits include reductions in use of service: hospital admissions/re-admissions, length of hospital stay, and emergency department visits typically declined. It is important that there often were reductions in mortality. Few studies reported neutral or mixed findings.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140284/1/tmj.2014.9981.pd

    Maternal Cigarette Smoking during Pregnancy and Offspring Externalizing Behavioral Problems: A Propensity Score Matching Analysis

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    A body of empirical research has revealed that prenatal exposure to tobacco smoke is related to a host of negative outcomes, including reduced cognitive abilities, later-life health problems, and childhood behavioral problems. While these findings are often interpreted as evidence of the causal role that prenatal exposure to tobacco smoke has on human phenotypes, emerging evidence has suggested that the association between prenatal exposure to tobacco smoke and behavioral phenotypes may be spurious. The current analysis of data from the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) revealed that the association between prenatal exposure to cigarette smoke and externalizing behavioral problems was fully accounted for by confounding factors. The implications that these findings have for policy and research are discussed

    Development and validation of a unifying pre-treatment decision tool for intracranial and extracranial metastasis-directed radiotherapy

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    BackgroundThough metastasis-directed therapy (MDT) has the potential to improve overall survival (OS), appropriate patient selection remains challenging. We aimed to develop a model predictive of OS to refine patient selection for clinical trials and MDT.Patients and methodsWe assembled a multi-institutional cohort of patients treated with MDT (stereotactic body radiation therapy, radiosurgery, and whole brain radiation therapy). Candidate variables for recursive partitioning analysis were selected per prior studies: ECOG performance status, time from primary diagnosis, number of additional non-target organ systems involved (NOS), and intracranial metastases.ResultsA database of 1,362 patients was assembled with 424 intracranial, 352 lung, and 607 spinal treatments (n=1,383). Treatments were split into training (TC) (70%, n=968) and internal validation (IVC) (30%, n=415) cohorts. The TC had median ECOG of 0 (interquartile range [IQR]: 0-1), NOS of 1 (IQR: 0-1), and OS of 18 months (IQR: 7-35). The resulting model components and weights were: ECOG = 0, 1, and > 1 (0, 1, and 2); 0, 1, and > 1 NOS (0, 1, and 2); and intracranial target (2), with lower scores indicating more favorable OS. The model demonstrated high concordance in the TC (0.72) and IVC (0.72). The score also demonstrated high concordance for each target site (spine, brain, and lung).ConclusionThis pre-treatment decision tool represents a unifying model for both intracranial and extracranial disease and identifies patients with the longest survival after MDT who may benefit most from aggressive local therapy. Carefully selected patients may benefit from MDT even in the presence of intracranial disease, and this model may help guide patient selection for MDT

    A new framework for host-pathogen interaction research

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    COVID-19 often manifests with different outcomes in different patients, highlighting the complexity of the host-pathogen interactions involved in manifestations of the disease at the molecular and cellular levels. In this paper, we propose a set of postulates and a framework for systematically understanding complex molecular host-pathogen interaction networks. Specifically, we first propose four host-pathogen interaction (HPI) postulates as the basis for understanding molecular and cellular host-pathogen interactions and their relations to disease outcomes. These four postulates cover the evolutionary dispositions involved in HPIs, the dynamic nature of HPI outcomes, roles that HPI components may occupy leading to such outcomes, and HPI checkpoints that are critical for specific disease outcomes. Based on these postulates, an HPI Postulate and Ontology (HPIPO) framework is proposed to apply interoperable ontologies to systematically model and represent various granular details and knowledge within the scope of the HPI postulates, in a way that will support AI-ready data standardization, sharing, integration, and analysis. As a demonstration, the HPI postulates and the HPIPO framework were applied to study COVID-19 with the Coronavirus Infectious Disease Ontology (CIDO), leading to a novel approach to rational design of drug/vaccine cocktails aimed at interrupting processes occurring at critical host-coronavirus interaction checkpoints. Furthermore, the host-coronavirus protein-protein interactions (PPIs) relevant to COVID-19 were predicted and evaluated based on prior knowledge of curated PPIs and domain-domain interactions, and how such studies can be further explored with the HPI postulates and the HPIPO framework is discussed
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