602 research outputs found

    Computational Study of a Generic T-tail Transport

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    This paper presents a computational study on the static and dynamic stability characteristics of a generic transport T-tail configuration under a NASA research program to improve stall models for civil transports. The NASA Tetrahedral Unstructured Software System (TetrUSS) was used to obtain both static and periodic dynamic solutions at low speed conditions for three Reynolds number conditions up to 60 deg angle of attack. The computational results are compared to experimental data. The dominant effects of Reynolds number for the static conditions were found to occur in the stall region. The pitch and roll damping coefficients compared well to experimental results up to up to 40 deg angle of attack whereas yaw damping coefficient agreed only up to 20 deg angle of attack

    Rak jelita grubego z potencjalnie resekcyjnymi przerzutami do wątroby: optymalizacja leczenia

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    Colorectal cancer is a common malignancy and often presents with synchronous or metachronous distant spread. For patients with hepatic metastases, resection is the principal curative option. Liberalization of the indications for hepatic resection has introduced a number of challenges related to the size, distribution, and number of metastases as well as the condition of the future liver remnant. Advances in systemic therapy have solidified its role as both an important adjunct to surgery and also for many patients as a mechanism to facilitate resection. In patients whose disease is marginally resectable as a consequence of the distribution of hepatic lesions that precludes complete resection or out of concern for the future liver remnant, a number of strategies have been advocated, including prehepatectomy systemic therapy, staged surgical approaches, ablative technologies, and preoperative portal vein embolization. It is the purpose of this review to discuss ways in which to optimize the treatment of patients with potentially resectable disease, specifically those who are judged to have “borderline” resectable situations.Rak jelita grubego jest często występującym nowotworem, w którego przebiegu mogą występować synchronicznie lub metachronicznie przerzuty odległe. Podstawową metodę leczenia w przypadku przerzutów do wątroby stanowi chirurgiczna resekcja. Rozszerzenie wskazań do leczenia operacyjnego przerzutów do wątroby przyniosło szereg wyzwań dotyczących wielkości przerzutów, ich lokalizacji i liczby, a także wydolności pozostawionego miąższu narządu. Postęp w leczeniu systemowym ugruntował rolę tej metody zarówno w postępowaniu uzupełniającym po leczeniu chirurgicznym, jak i indukcyjnym ułatwiającym resekcję przerzutów. U chorych z przerzutami o wątpliwej resekcyjności z powodu rozmieszczenia zmian w wątrobie wykluczającego doszczętne wycięcie przy zachowaniu akceptowalnej funkcji pozostawionego miąższu, podejmuje się próby stosowania różnych metod, w tym neoadiuwantowego leczenia systemowego, kilkuetapowych resekcji, a także ablacji i przedoperacyjnej embolizacji żyły wrotnej. W niniejszym opracowaniu przedstawiono strategie optymalizacji leczenia chorych z potencjalnie lub w szczególności z granicznie resekcyjnymi zmianami przerzutowymi w wątrobie

    Endoscopic Ultrasound Guided Drainage of Peri-Rectal Collections: A Salvage Approach

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    Abdominal and pelvic abscesses can occur as a consequence of surgery and are associated with significant morbidity and mortality. It is well accepted that the primary treatment is antibiotic therapy and minimally invasive drainage. Surgical measures are typically reserved for patients with luminal perforations or those who do not respond to conservative measures. Previously available modalities of drainage involved percutaneous and computed tomography guided access. Recently, endoscopic ultrasound guided aspiration has emerged as a safe alternative for management of intra-abdominal abscesses. Since its first application for peripancreatic drainage, endoscopic ultrasound techniques and technologies have significantly evolved. Endoscopic ultrasound interventions can now be performed quickly, safely and precisely, even outside of the operating room. Multiple reports and case series demonstrate the utility for endoscopic ultrasound guided drainage of fluid collections, providing they are in close proximity to the intestinal lumen. As a result, extension of this approach’s indications has been considered. Endoscopic ultrasound-guided drainage and stenting is an emerging approach which provides an accurate, efficient and safe alternative for the management of intra-abdominal collections. Furthermore, endoscopic ultrasound techniques may allow access to areas that are inaccessible or technically challenging with computed tomography guided or surgical approaches as illustrated in our case. Additionally, the internal nature of the access point may offer patients a more comfortable experience; and can facilitate preservation of enteral feeding routes or intestinal transit. This case demonstrated the clinical complexity that often characterizes the management of post surgical complications, particularly inflammatory collections. It further delineates the utility of Endoscopic ultrasound-fine needle aspiration techniques in the treatment of pelvic abscesses, even as a salvage therapy, where other approaches fail. EUS guided drainage should strongly be considered at multiple tiers of all treatment algorithms as a viable, and in some instances preferable therapeutic modality for patients presenting with intra-abdominal collections

    Preliminary Test Results for Stability and Control Characteristics of a Generic T-Tail Transport Airplane at High Angle of Attack

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    Tests of a generic T-tail transport airplane, in flaps-up configuration, were conducted using two wind tunnels, a water tunnel, and computational fluid dynamics. Static force and moment testing, forced oscillation testing and dye flow visualization test techniques were used. The purpose of the testing was to obtain stability and control characteristics for development of a research flight simulator aerodynamic database. The purpose of that database was for assessment of aerodynamic model fidelity requirements to train airline pilots to recognize and recover from full stall conditions. Preliminary results, at initial stall conditions, include: an unstable stall pitch break, and near-neutral roll damping. Preliminary results, at deep stall conditions, include: a potential static longitudinal trim condition at approximately 35 degrees angle of attack, large aerodynamic asymmetries, and localized unstable dynamic stability

    Passing the Turing Test Does Not Mean the End of Humanity

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    In this paper we look at the phenomenon that is the Turing test. We consider how Turing originally introduced his imitation game and discuss what this means in a practical scenario. Due to its popular appeal we also look into different representations of the test as indicated by numerous reviewers. The main emphasis here, however, is to consider what it actually means for a machine to pass the Turing test and what importance this has, if any. In particular does it mean that, as Turing put it, a machine can “think”. Specifically we consider claims that passing the Turing test means that machines will have achieved human-like intelligence and as a consequence the singularity will be upon us in the blink of an eye

    Oxytocin, a Novel Treatment for Methamphetamine Use Disorder

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    The treatment of substance abuse with oxytocin is a novel approach to a challenging public health issue that continues to contribute to a growing economic cost for societies worldwide. Methamphetamine addiction is one of the leading causes of mortality worldwide, and despite advances in understanding the neurobiology of methamphetamine addiction, treatment options are limited. There are no medications that the Food and Drug Administration currently approves for stimulant use disorder. Off-label use of therapies for stimulant misuse include antidepressants, anxiolytics, and milder stimulants as replacement agents. Due to the shortcomings of these attempts to treat a complicated psychiatric disorder, recent attention to oxytocin therapy (OT) has gained momentum in clinical studies as a possible therapy in the context of social stress, social anxiety, social cognition, and psychosis. Oxytocin produces enhanced connectivity between cortical regions. The results from studies in rodents with OT suggest that central neuromodulation of oxytocin may be beneficial across transition states of stimulant dependence and may alleviate intense withdrawal symptoms. Studies of oxytocin in the context of other drugs of abuse, including cocaine, cannabis, and alcohol, also support the potential of oxytocin to treat stimulant use disorder, methamphetamine type. Methamphetamine abuse continues to be a significant cause of distress and dysfunction throughout the world. The effects of oxytocin on methamphetamine use outlined in this review should act as a catalyst for further investigation into the efficacy of treating stimulant use disorder, methamphetamine type with oxytocin in humans. More human-based research should initiate studies involving the long-term efficacy, side effects, and patient selection

    Hydrostatic intestinal edema induced signaling pathways: potential role of mechanical forces.

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    BACKGROUND: Hydrostatic intestinal edema initiates a signal transduction cascade that results in smooth muscle contractile dysfunction. Given the rapid and concurrent alterations in the mechanical properties of edematous intestine observed with the development of edema, we hypothesize that mechanical forces may serve as a stimulus for the activation of certain signaling cascades. We sought to examine whether isolated similar magnitude mechanical forces induced the same signal transduction cascades associated with edema. METHODS: The distal intestine from adult male Sprague Dawley rats was stretched longitudinally for 2 h to 123% its original length, which correlates with the interstitial stress found with edema. We compared wet-to-dry ratios, myeloperoxidase activity, nuclear signal transduction and activator of transcription (STAT)-3 and nuclear factor (NF)-kappa B DNA binding, STAT-3 phosphorylation, myosin light chain phosphorylation, baseline and maximally stimulated intestinal contractile strength, and inducible nitric oxide synthase (iNOS) and sodium hydrogen exchanger 1-3 messenger RNA (mRNA) in stretched and adjacent control segments of intestine. RESULTS: Mechanical stretch did not induce intestinal edema or an increase in myeloperoxidase activity. Nuclear STAT-3 DNA binding, STAT-3 phosphorylation, and nuclear NF-kappa B DNA binding were significantly increased in stretched seromuscular samples. Increased expression of sodium hydrogen exchanger 1 was found but not an increase in iNOS expression. Myosin light chain phosphorylation was significantly decreased in stretched intestine as was baseline and maximally stimulated intestinal contractile strength. CONCLUSION: Intestinal stretch, in the absence of edema/inflammatory/ischemic changes, leads to the activation of signaling pathways known to be altered in intestinal edema. Edema may initiate a mechanotransductive cascade that is responsible for the subsequent activation of various signaling cascades known to induce contractile dysfunction

    Finding minimal action sequences with a simple evaluation of actions

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    Animals are able to discover the minimal number of actions that achieves an outcome (the minimal action sequence). In most accounts of this, actions are associated with a measure of behavior that is higher for actions that lead to the outcome with a shorter action sequence, and learning mechanisms find the actions associated with the highest measure. In this sense, previous accounts focus on more than the simple binary signal of “was the outcome achieved?”; they focus on “how well was the outcome achieved?” However, such mechanisms may not govern all types of behavioral development. In particular, in the process of action discovery (Redgrave and Gurney, 2006), actions are reinforced if they simply lead to a salient outcome because biological reinforcement signals occur too quickly to evaluate the consequences of an action beyond an indication of the outcome’s occurrence. Thus, action discovery mechanisms focus on the simple evaluation of “was the outcome achieved?” and not “how well was the outcome achieved?” Notwithstanding this impoverishment of information, can the process of action discovery find the minimal action sequence? We address this question by implementing computational mechanisms, referred to in this paper as no-cost learning rules, in which each action that leads to the outcome is associated with the same measure of behavior. No-cost rules focus on “was the outcome achieved?” and are consistent with action discovery. No-cost rules discover the minimal action sequence in simulated tasks and execute it for a substantial amount of time. Extensive training, however, results in extraneous actions, suggesting that a separate process (which has been proposed in action discovery) must attenuate learning if no-cost rules participate in behavioral development. We describe how no-cost rules develop behavior, what happens when attenuation is disrupted, and relate the new mechanisms to wider computational and biological context
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