4,912 research outputs found

    A Capacitated Facility Location Approach for the Tanker Employment Problem

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    Air refueling is conducted to provide rapid response, increased range, and extended airborne operations for bombers, fighters, airlift, command and control, and intelligence, surveillance, and reconnaissance aircraft. The planning and scheduling of limited tanker resources during employment operations is a major concern for Air Mobility Command (AMC). AMC does not currently have a simple tool that runs in a short amount of time to aid in planning operations. The tool developed allows AMC to input several sorties consisting of various aircraft types and armaments. Each sortie contains a base of origin, and is assumed to be attacking or patrolling in an engagement zone defined by the user. The user is also able to specify the locations of military tanker aircraft. The main goal of the tool is to assign the tankers to anchor areas, surrounding the engagement zone so that all receivers can be refueled during their attack operations. Secondary goals include minimizing the number of tankers required (or maximizing the number of receivers supported), and limiting the total flight distance for the tanker aircraft. The TET tool uses the heuristic technique tabu search to determine an assignment of tankers and sorties to anchor areas during employment

    IUCN, National Parks, and Protected Areas: Priorities for Action

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    In order to ensure that the full range of species and natural ecosystems continue to form part of the human habitat, national parks and other types of protected areas must be better designed and managed than is usually the case at present. While IUCN has a long history of involvement in protected areas, often in cooperation with UNESCO, the World Wildlife Fund, and UNEP, the World National Parks Congress (held in Bali, Indonesia, during 11-22 October 1982) marked a major turning-point in promoting protected areas as part of the social and economic development process. In this approach, the Congress provided ways and means for the philosophy of the World Conservation Strategy (1980) to be put into action on the groun

    Signal Analysis Algorithms for Optimized Fitting of Nonresonant Laser Induced Thermal Acoustics Damped Sinusoids

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    This study seeks a numerical algorithm which optimizes frequency precision for the damped sinusoids generated by the nonresonant LITA technique. It compares computed frequencies, frequency errors, and fit errors obtained using five primary signal analysis methods. Using variations on different algorithms within each primary method, results from 73 fits are presented. Best results are obtained using an AutoRegressive method. Compared to previous results using Prony s method, single shot waveform frequencies are reduced approx.0.4% and frequency errors are reduced by a factor of approx.20 at 303K to approx. 0.1%. We explore the advantages of high waveform sample rates and potential for measurements in low density gases

    Regulation of actin cytoskeleton architecture by Eps8 and Abi1

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    BACKGROUND: The actin cytoskeleton participates in many fundamental processes including the regulation of cell shape, motility, and adhesion. The remodeling of the actin cytoskeleton is dependent on actin binding proteins, which organize actin filaments into specific structures that allow them to perform various specialized functions. The Eps8 family of proteins is implicated in the regulation of actin cytoskeleton remodeling during cell migration, yet the precise mechanism by which Eps8 regulates actin organization and remodeling remains elusive. RESULTS: Here, we show that Eps8 promotes the assembly of actin rich filopodia-like structures and actin cables in cultured mammalian cells and Xenopus embryos, respectively. The morphology of actin structures induced by Eps8 was modulated by interactions with Abi1, which stimulated formation of actin cables in cultured cells and star-like structures in Xenopus. The actin stars observed in Xenopus animal cap cells assembled at the apical surface of epithelial cells in a Rac-independent manner and their formation was accompanied by recruitment of N-WASP, suggesting that the Eps8/Abi1 complex is capable of regulating the localization and/or activity of actin nucleators. We also found that Eps8 recruits Dishevelled to the plasma membrane and actin filaments suggesting that Eps8 might participate in non-canonical Wnt/Polarity signaling. Consistent with this idea, mis-expression of Eps8 in dorsal regions of Xenopus embryos resulted in gastrulation defects. CONCLUSION: Together, these results suggest that Eps8 plays multiple roles in modulating actin filament organization, possibly through its interaction with distinct sets of actin regulatory complexes. Furthermore, the finding that Eps8 interacts with Dsh and induced gastrulation defects provides evidence that Eps8 might participate in non-canonical Wnt signaling to control cell movements during vertebrate development

    Effects of Preferred and Non-preferred Concurrent Activities during Self-Control Training in a School for Autism

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    Objectives. Self-control training is comprised of a progressively lengthened delay to reinforcement, during which the individual can engage in some activity until the temporally distant reinforcer is provided.  Though availability of an activity concurrent to the delay has been shown to increase self-control, little is known about relative effects of differing qualities of activities.  The purpose of the study was to examine differential effects of preferred and non-preferred activities during delays in self-control training.  Methods. Using a multiple baseline design, three students with autism consistently demonstrated impulsive choices and low engagement in tasks.  During self-control training, participants chose between a smaller, immediate reinforcer and a larger reinforcer following a short delay with an alternating preferred and non-preferred response requirement.  After success was observed in either preferred or non-preferred conditions, the delay associated with that condition was progressively lengthened.  Last, participants chose which activity was available during the delay, and choices were monitored as delays associated with chosen conditions were extended. Results. During training, two participants demonstrated near exclusive self-control choices. All three increased delay tolerance at similar rates regardless of activity preference, and more frequently chose the progressive/preferred alternative than the progressive/non-preferred alternative though delay requirements were greater. Conclusions. Self-control can be established by starting with minimal delays to reinforcement and progressively extending the delay after success is observed, regardless of whether a work- or preferred-activity is available during the delay.  However, providing an option for a preferred activity may help to “bridge the gap” to more temporally distant reinforcers

    Modeling a Civil Event Case Study for Consequence Management Using the IMPRINT Forces Module

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    A critical challenge in the Consequence Management (CM) domain is the appropriate allocation of necessary and skilled military and civilian personnel and materiel resources in unexpected emergencies. To aid this process we used the Forces module in the Improved Performance Research Integration Tool (IMPRINT). This module enables analysts to enter personnel and equipment capabilities, prioritized schedules and numbers available, along with unexpected emergency requirements in order to assess force response requirements. Using a suspected terrorist threat on a college campus, we developed a test case model which exercised the capabilities of the module, including the scope and scale of operations. The model incorporates data from multiple sources, including daily schedules and frequency of events such as fire calls. Our preliminary results indicate that the model can predict potential decreases in civilian emergency response coverage due to an involved unplanned incident requiring significant portions of police, fire and civil responses teams

    Proteomic analyses reveal misregulation of LIN28 expression and delayed timing of glial differentiation in human iPS cells with MECP2 loss-of-function.

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    Rett syndrome (RTT) is a pervasive developmental disorder caused by mutations in MECP2. Complete loss of MECP2 function in males causes congenital encephalopathy, neurodevelopmental arrest, and early lethality. Induced pluripotent stem cell (iPSC) lines from male patients harboring mutations in MECP2, along with control lines from their unaffected fathers, give us an opportunity to identify some of the earliest cellular and molecular changes associated with MECP2 loss-of-function (LOF). We differentiated iPSC-derived neural progenitor cells (NPCs) using retinoic acid (RA) and found that astrocyte differentiation is perturbed in iPSC lines derived from two different patients. Using highly stringent quantitative proteomic analyses, we found that LIN28, a gene important for cell fate regulation and developmental timing, is upregulated in mutant NPCs compared to WT controls. Overexpression of LIN28 protein in control NPCs suppressed astrocyte differentiation and reduced neuronal synapse density, whereas downregulation of LIN28 expression in mutant NPCs partially rescued this synaptic deficiency. These results indicate that the pathophysiology of RTT may be caused in part by misregulation of developmental timing in neural progenitors, and the subsequent consequences of this disruption on neuronal and glial differentiation
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