3,236 research outputs found

    On Correcting Inputs: Inverse Optimization for Online Structured Prediction

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    Algorithm designers typically assume that the input data is correct, and then proceed to find "optimal" or "sub-optimal" solutions using this input data. However this assumption of correct data does not always hold in practice, especially in the context of online learning systems where the objective is to learn appropriate feature weights given some training samples. Such scenarios necessitate the study of inverse optimization problems where one is given an input instance as well as a desired output and the task is to adjust the input data so that the given output is indeed optimal. Motivated by learning structured prediction models, in this paper we consider inverse optimization with a margin, i.e., we require the given output to be better than all other feasible outputs by a desired margin. We consider such inverse optimization problems for maximum weight matroid basis, matroid intersection, perfect matchings, minimum cost maximum flows, and shortest paths and derive the first known results for such problems with a non-zero margin. The effectiveness of these algorithmic approaches to online learning for structured prediction is also discussed.Comment: Conference version to appear in FSTTCS, 201

    The Role of Fire in the Regeneration of Table Mountain Pine in the Southern Appalachian Mountains

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    Table Mountain pine (Pinus pungens Lam.) is highly intolerant, serotinous-coned species endemic to the Appalachian Mountains. Before it can successfully be regenerated, three conditions must occur--(1) heat must be present to open its serotinous cones, (2) seed must fall on mineral soil, and (3) the existing forest canopy must be removed in to expose seedlings to full sunlight. These conditions are only met in the advent of fire. This study was conducted in stands of Table Mountain pine that were burned by wildfires to see which burning conditions best regenerate the species. It showed that the best regeneration occurred in areas burned by crown fires. While regeneration was found in areas burned by hot surface fires that removed some overstory vegetation, very little regeneration was found where light surface fires had burned. This study showed that adequate regeneration of Table Mountain pine had occurred following a fire in a 20 year-old stand. However, an 11 year-old stand sampled had produced very few cones, and it is doubtful that enough seed was being produced to regenerate that stand should it burn now. This study also raised questions concerning the need for fire management programs to perpetuate this fire-dependent species

    Determination of the Validity and Reliability of a Modified Osteoporosis Health Belief Scale and Osteoporosis Self-Efficacy Scale to Include Vitamin D

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    Background/Purpose: Osteoporosis health beliefs and osteoporosis self-efficacy scales are commonly used in determining educational needs towards osteoporosis prevention but lack vitamin D content. This study examined the validity and reliability of Osteoporosis Health Belief Scale (OHBS) and Osteoporosis Self Efficacy Scale (OSES) modified scales which included vitamin D content in order to be used in studies to increase vitamin D and calcium intakes for prevention of osteoporosis. Methods: Participants were a convenience sample of 153 college-aged adults at a Midwestern university. Factor analysis, Cronbach ?, and Intra-class correlation coefficients determined validity, internal consistency, and test-retest reliability of the modified scales. Results: The OHBS-D Cronbach ? was r = .82; subscales ranged from .75-.87. The OSES-D Cronbach ? was r = .98; subscales ranged from .96-.98. Total ICC for OHBS-D and OSES-D was .79 and .97 respectively. Factor analysis extracted eight factors for the OHBS-D and three factors for the OSES-D, which explained 52.2% and 82.2% of the total variance in all variables accounted for by each factor respectively. Conclusion: The modified scales were valid and reliable indicating they could be used to determine osteoporosis related health beliefs and self-efficacy

    Overseas Contingency Operations Contracts After Iraq: Enabling Financial Management Research and Transparency Through Contract Labeling

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    Panel #3: Initiatives in Contract ManagementAcquisition Research: Creating Synergy for Informed Change. 17th Annual Acquisition Research Symposiu

    Communication Responsibilities of the International Agricultural Research Centers; Designing a Program Viewers Remember; Get the Facts, Not the Chicken: How to Use and Instructional Film; Precision Journalism; News Writing

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    Reviews of Communication Responsibilities of the International Agricultural Research Centers, published by Agricultural Developmenl Council, Inc., and the International Rice Research Institute (IRRI); Designing a Program Viewers Remember, by Gary A. Witt; and Get the Facts, Not the Chicken: How to Use and Instructional Film, by Gary A. Witt; Precision Journalism, by Phillip Meyer; and News Writing\u3c,em\u3e, by George A. Hough III

    The genetic basis for adaptation of model-designed syntrophic co-cultures.

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    Understanding the fundamental characteristics of microbial communities could have far reaching implications for human health and applied biotechnology. Despite this, much is still unknown regarding the genetic basis and evolutionary strategies underlying the formation of viable synthetic communities. By pairing auxotrophic mutants in co-culture, it has been demonstrated that viable nascent E. coli communities can be established where the mutant strains are metabolically coupled. A novel algorithm, OptAux, was constructed to design 61 unique multi-knockout E. coli auxotrophic strains that require significant metabolite uptake to grow. These predicted knockouts included a diverse set of novel non-specific auxotrophs that result from inhibition of major biosynthetic subsystems. Three OptAux predicted non-specific auxotrophic strains-with diverse metabolic deficiencies-were co-cultured with an L-histidine auxotroph and optimized via adaptive laboratory evolution (ALE). Time-course sequencing revealed the genetic changes employed by each strain to achieve higher community growth rates and provided insight into mechanisms for adapting to the syntrophic niche. A community model of metabolism and gene expression was utilized to predict the relative community composition and fundamental characteristics of the evolved communities. This work presents new insight into the genetic strategies underlying viable nascent community formation and a cutting-edge computational method to elucidate metabolic changes that empower the creation of cooperative communities

    Patient perspectives on sharing anonymised personal health data using a digital system for dynamic consent and research feedback: a qualitative study

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    Background: Electronic health records are widely acknowledged to provide an important opportunity to anonymize patient-level health care data and collate across populations to support research. Nonetheless, in the wake of public and policy concerns about security and inappropriate use of data, conventional approaches toward data governance may no longer be sufficient to respect and protect individual privacy. One proposed solution to improve transparency and public trust is known as Dynamic Consent, which uses information technology to facilitate a more explicit and accessible opportunity to opt out. In this case, patients can tailor preferences about whom they share their data with and can change their preferences reliably at any time. Furthermore, electronic systems provide opportunities for informing patients about data recipients and the results of research to which their data have contributed. Objective: To explore patient perspectives on the use of anonymized health care data for research purposes. To evaluate patient perceptions of a Dynamic Consent model and electronic system to enable and implement ongoing communication and collaboration between patients and researchers. Methods: A total of 26 qualitative interviews and three focus groups were conducted that included a video presentation explaining the reuse of anonymized electronic patient records for research. Slides and tablet devices were used to introduce the Dynamic Consent system for discussion. A total of 35 patients with chronic rheumatic disease with varying levels of illness and social deprivation were recruited from a rheumatology outpatient clinic; 5 participants were recruited from a patient and public involvement health research network. Results: Patients were supportive of sharing their anonymized electronic patient record for research, but noted a lack of transparency and awareness around the use of data, making it difficult to secure public trust. While there were general concerns about detrimental consequences of data falling into the wrong hands, such as insurance companies, 39 out of 40 (98%) participants generally considered that the altruistic benefits of sharing health care data outweighed the risks. Views were mostly positive about the use of an electronic interface to enable greater control over consent choices, although some patients were happy to share their data without further engagement. Participants were particularly enthusiastic about the system as a means of enabling feedback regarding data recipients and associated research results, noting that this would improve trust and public engagement in research. This underlines the importance of patient and public involvement and engagement throughout the research process, including the reuse of anonymized health care data for research. More than half of patients found the touch screen interface easy to use, although a significant minority, especially those with limited access to technology, expressed some trepidation and felt they may need support to use the system. Conclusions: Patients from a range of socioeconomic backgrounds viewed a digital system for Dynamic Consent positively, in particular, feedback about data recipients and research results. Implementation of a digital Dynamic Consent system would require careful interface design and would need to be located within a robust data infrastructure; it has the potential to improve trust and engagement in electronic medical record research

    Characterization of Semi-Autonomous On-Orbit Assembly CubeSat Constellation

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    Demand for more complex space systems is ever increasing as the scale of the future missions expands. Accordingly, much focus has been given recently to innovations in on-orbit assembly and servicing to ensure those missions are executed in a time-efficient manner. The past on-orbit servicing demonstrations have involved large satellites that were designed to dock/berth and service specific client satellites, and did not leverage the current advancements in small satellite technology. The U.S. Naval Academy (USNA) is contributing to advancing the onorbit servicing and assembly technology with a next-generation robotic arm Intelligent Space Assembly Robot (ISAR) system, which is envisioned to operate independently or as a constellation of 3U CubeSats and seeks to demonstrate semi-autonomous robotic assembly capabilities on-orbit on a nano-satellite scale. This paper will present an overview of the ISAR system, outline design, operation, and demonstration modifications for the on-orbit demonstrator, analyze the results from the ground test platform, and discuss the interfacing between existing robotic operations structures and advanced sensors. It will also focus on the analysis of cost effectiveness of the proposed mission architecture by characterizing the operation envelope of CubeSat-based assembly satellite constellations and volumetric efficiency analysis of on-orbit assembly using “Bin of Parts”

    Widespread recombination, reassortment, and transmission of unbalanced compound viral genotypes in natural arenavirus infections.

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    Arenaviruses are one of the largest families of human hemorrhagic fever viruses and are known to infect both mammals and snakes. Arenaviruses package a large (L) and small (S) genome segment in their virions. For segmented RNA viruses like these, novel genotypes can be generated through mutation, recombination, and reassortment. Although it is believed that an ancient recombination event led to the emergence of a new lineage of mammalian arenaviruses, neither recombination nor reassortment has been definitively documented in natural arenavirus infections. Here, we used metagenomic sequencing to survey the viral diversity present in captive arenavirus-infected snakes. From 48 infected animals, we determined the complete or near complete sequence of 210 genome segments that grouped into 23 L and 11 S genotypes. The majority of snakes were multiply infected, with up to 4 distinct S and 11 distinct L segment genotypes in individual animals. This S/L imbalance was typical: in all cases intrahost L segment genotypes outnumbered S genotypes, and a particular S segment genotype dominated in individual animals and at a population level. We corroborated sequencing results by qRT-PCR and virus isolation, and isolates replicated as ensembles in culture. Numerous instances of recombination and reassortment were detected, including recombinant segments with unusual organizations featuring 2 intergenic regions and superfluous content, which were capable of stable replication and transmission despite their atypical structures. Overall, this represents intrahost diversity of an extent and form that goes well beyond what has been observed for arenaviruses or for viruses in general. This diversity can be plausibly attributed to the captive intermingling of sub-clinically infected wild-caught snakes. Thus, beyond providing a unique opportunity to study arenavirus evolution and adaptation, these findings allow the investigation of unintended anthropogenic impacts on viral ecology, diversity, and disease potential

    The Future Role of Strategic Landpower

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    Recent Russian aggression in Ukraine has reenergized military strategists and senior leaders to evaluate the role of strategic Landpower. American leadership in the European theater has mobilized allies and partners to reconsider force postures for responding to possible aggression against NATO members. Although Russian revisionist activity remains a threat in Europe, the challenges in the Pacific for strategic Landpower must also be considered. At the same time, the homeland, the Arctic, climate change, and the results of new and emerging technology also challenge the application of strategic Landpower. This publication serves as part of an enduring effort to evaluate strategic Landpower’s role, authorities, and resources for accomplishing the national strategic goals the Joint Force may face in the next conflict. This study considers multinational partners, allies, and senior leaders that can contribute to overcoming these enduring challenges. The insights derived from this study, which can be applied to both the European and Indo-Pacific theaters, should help leaders to consider these challenges, which may last a generation. Deterrence demands credible strategic response options integrated across warfighting functions. This valuable edition will continue the dialogue about addressing these issues as well as other emerging ones.https://press.armywarcollege.edu/monographs/1959/thumbnail.jp
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