505 research outputs found

    A Consumer-Based Model of Competitive Diffusion of Two Goods: The Effects of Network Externalities and Local Interactions

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    The diffusion of two competitive, interchangeable, and durable goods is studied under the framework of a spatial game where consumers are distributed on a two-dimensional square lattice and play 3×\times3 symmetric coordination-like games with their nearest neighbors. There are three strategies, either consuming a product A or B, or a strategy C of not consuming either A or B. The payoff matrix of the game contains the positive effects of network externality, that is, the payoffs are increasing functions of the number of agents adopting the strategies A or B. Both simulations and mean-field approximation show that the existence of the positive effects of the network externality amplifies any slight initial difference in the number of agents who adopt either A or B and eventually promotes the superior product to take over the entire market. On the other hand, without effects of the network externality the slight initial difference is not enlarged and both superior and inferior products are observed to coexist by forming clusters in the market. Moreover, the effects of innovation factors that help an inferior product to retake the market are studied. It is shown that both the timing and size of the innovation factor matter for an inferior product in order to retake the market.competitive diffusion, network externality, local interaction, global externality, local externality, evolutionary game, spatial game

    The Spatial Distribution of Backscattered Electrons Revisited with a New Monte Carlo Simulation

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    A Monte Carlo simulation program including the discrete energy loss process has been developed, based on the Mott cross section for elastic scattering and the Vriens cross section for inelastic scattering. A deficiency of the previous model which is based on the screened Rutherford cross section and the Bethe law is made clear, from comparison between the new and old results such as the energy distribution of backscattered electrons for a Cu target. With the new Monte Carlo model, the radial spreading and penetration depth of both all and low-loss backscattered electrons have been studied for the Cu target at electron energies of 5.10 and 20 keV. From these studies, it is found that the electron exit angle dependence of the spatial spreading is more significant with the low-loss backscattered electrons and a very high resolution of 2 to 3 nm can be obtained even with backscattered electrons

    THE REBOUND OF THE BODY USING RUNNING-SPECIFIC PROSTHESES IN UNILATERAL TRANSFEMORAL AMPUTEES

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    Although the elastic bounce of the body is considered a prerequisite for running, the rebound strategy in individuals with lower extremity amputation is not well known. This study aims to investigate the rebound strategy at different running speeds in unilateral transfemoral amputees (uTFAs) wearing running-specific prostheses (RSPs). On an instrumented treadmill, eight uTFAs ran at incremental speeds (30%, 40%, 50%, 60%, 70%, and 80% of the average speed of their 100-m personal records). The rebound strategy of the unaffected and affected limbs is evaluated using the ratio of the natural frequency of the spring-mass system (fsist) to the step frequency (fstep). At all speeds, fsist/fstep in the unaffected limb is considerably greater than that in the affected one. The interlimb differences in fsist/fstep tended to increase with the speed. These results suggest that the rebound strategy is not the same for the unaffected and affected limbs in uTFAs across a range of speeds, and that uTFAs wearing RSPs perform bouncing steps using the alternate asymmetric rebound strategy (fstep \u3c fsist) through different limbs

    Anesthetic management of a patient undergoing liver transplantation who had previous coronary artery bypass grafting using an in situ right gastroepiploic artery.

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    We describe successful anesthetic management during living-donor liver transplantation in a 63-year-old man with previous coronary artery bypass grafting (CABG) that employed an in situ right gastroepiploic artery (RGEA). Anesthesia was maintained with 1.5% isoflurane in air/oxygen and fentanyl. A five-lead electrocardiogram, transesophageal echocardiogram, and pacing pulmonary artery catheter evaluated cardiac function. A pacing wire was inserted through the catheter to prepare for intraoperative severe bradyarrhythmia. Olprinone and nicorandil were continuously infused to prevent decrease in coronary arterial blood flow and the collapse of cardiac function. Avoiding disruption of circulation to coronary arteries through injury or spasm of the RGEA graft and preparing for cardiac insufficiency during liver transplantation of a patient with previous CABG using an in situ RGEA is critical

    Investigation of automotive light blinking pattern conveying a driver's intention to yield

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    This paper proposes a method of conveying a driver’s intention to yield by blinking automotive lighting. Generally, headlight flashing indicates a driver’s intention to yield to another driver or pedestrians in Japan. However, this signaling method can have several meanings, including warning other drivers of road dangers such as crashed cars, or informing other drivers of the presence of a pedestrian. There is a possibility of a misunderstanding, increasing the risk of accidents. Therefore, we have investigated an effective method for facilitating communication in traffic. This study focuses on nonverbal communication in which blinking lights convey the driver’s intentions to others. In this study, visibility is not considered. Nine blinking patterns that changed the light colors, waveform, and blinking cycle were presented to fifteen healthy participants, and visual impressions were evaluated to identify the most suitable blinking patterns. These nine patterns indicate a driver’s intention to yield to pedestrians and other drivers. The results indicated that a blue-green blinking pattern in which luminance changes with a triangular wave pattern with a one-second cycle was best conveyed the intention to yield

    Environmental Study in Elementary Geography in the United Kingdom by Analysis of Geographical School’s Textbook

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    Environmental education in elementary school in Japan is defined as “Moral Education” by the national curriculum. However, environmental education is one of the most important contents in geographical education. This study aims to clarify the contents in elementary geography in the United Kingdom by analyzing the elementary geographical textbook, in order to develop the basic environmental geographical education. And also we want to know how to educate environmental study in elementary school and how to improve it, from the view point of ESD (“Education for Sustainable Development”). Analyzed the elementary geographical textbooks, we find that it is effective for environmental education in UK to use various activities. All geographical textbooks foster problem solving abilities by using geographical activities and rearing scientific thinking

    Acquisition of Viewpoint Transformation and Action Mappings via Sequence to Sequence Imitative Learning by Deep Neural Networks

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    We propose an imitative learning model that allows a robot to acquire positional relations between the demonstrator and the robot, and to transform observed actions into robotic actions. Providing robots with imitative capabilities allows us to teach novel actions to them without resorting to trial-and-error approaches. Existing methods for imitative robotic learning require mathematical formulations or conversion modules to translate positional relations between demonstrators and robots. The proposed model uses two neural networks, a convolutional autoencoder (CAE) and a multiple timescale recurrent neural network (MTRNN). The CAE is trained to extract visual features from raw images captured by a camera. The MTRNN is trained to integrate sensory-motor information and to predict next states. We implement this model on a robot and conducted sequence to sequence learning that allows the robot to transform demonstrator actions into robot actions. Through training of the proposed model, representations of actions, manipulated objects, and positional relations are formed in the hierarchical structure of the MTRNN. After training, we confirm capability for generating unlearned imitative patterns

    Inference of S-system models of genetic networks using Product Unit Neural Networks

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    In this study, we proposed the method of inference of genetic networks which expresses the regulation of genes. The proposed method does not solve the differential equations, learns the genetic networks using Product-Unit-Neural- Network (PUNN) and infer the S-system model of genetic networks which describes a set of differential equations. The experimental results show the proposal method is 160 times faster than the previous method which estimated S-system model of genetic networks while maintaining equivalent performance to the previous method. © 2008 IEEE

    Extent of sympathectomy affects postoperative compensatory sweating and satisfaction in patients with palmar hyperhidrosis

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    Purpose: Endoscopic thoracic sympathectomy (ETS) for the treatment of palmar hyperhidrosis is generally performed at one or two levels ranging between T2 and T4; however, compensatory sweating (CS) is an occasional bothersome side effect. The aim of our study was to evaluate the association between the extent of ETS and the degree of postoperative CS and palmar sweating, as well as patient satisfaction. Methods: The participants represented a consecutive series of 76 patients who underwent bilateral ETS for palmar hyperhidrosis at level T2 and/or T3. Patients were interviewed by postal questionnaires to assess their self-reported degree of postoperative palmar sweating and CS and their outcome satisfaction. Of the 53 patients who replied to the postal questionnaire, 25 underwent bilateral ETS at one level (group A), and 27 underwent bilateral ETS at two levels (group B). One patient who underwent asymmetrical sympathectomy was excluded. Results: The degree of postoperative palmar sweating was significantly lower in group B than in group A. The severity of CS was significantly higher in group B than in group A. The severity of CS was significantly inversely correlated with the degree of patient satisfaction. However, the degree of postoperative palmar sweating was not correlated with the degree of patient satisfaction. Conclusions: Compared to ETS at two levels, single-level ETS of T2 or T3 reduces postoperative palmar sweating to a milder degree, and causes CS to a less severe degree. The severity of CS is inversely correlated with the degree of patient satisfaction

    Compensatory Thrombopoietin Production from the Liver and Bone Marrow Stimulates Thrombopoiesis of Living Rat Megakaryocytes in Chronic Renal Failure

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    Background/Aims: Decreased thrombopoiesis has been ascribed a role in the pathogenesis of uremic bleeding in chronic renal failure (CRF). However, serum thrombopoietin (TPO) levels are usually elevated in CRF patients, suggesting increased thrombopoiesis. The aim of this study was to determine the thrombopoietic activity in CRF. Methods: Male Sprague-Dawley rats that underwent 5/6 nephrectomy were used as the model of CRF. Age-matched sham-operated rats were used as controls. Single megakaryocytes were isolated from the rat bone marrow, and their size distribution was examined. Megakaryocyte membrane invaginations were monitored by confocal imaging of di-8-ANEPPS staining, and patch clamp whole-cell recordings of membrane capacitance. TPO gene expression was assessed in various tissues. Results: Circulating platelet counts and the number of large megakaryocytes were increased in the bone marrow of CRF rats. Massive di-8-ANEPPS staining and increased membrane capacitance in large megakaryocytes demonstrated increased membrane invaginations. Unaffected Kv1.3-channel currents per cell surface area demonstrated unaltered channel densities. TPO transcription was decreased in the renal cortex but increased in the liver and bone marrow of CRF rats. Conclusion: Increased thrombopoiesis in CRF was thought to be a reactive mechanism to platelet dysfunction. Increased TPO production from the liver and bone marrow compensated for decreased production from damaged kidneys
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