526 research outputs found

    Origin of Critical Behavior in Ethernet Traffic

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    We perform a simplified Ethernet traffic simulation in order to clarify the physical mechanism of the phase transition behavior which has been experimentally observed in the flow density fluctuation of Internet traffic. In one phase traffics from nodes connected with an Ethernet cable are mixed, and in the other phase, the nodes alternately send bursts of packets. The competition of sending packets among nodes and the binary exponential back-off algorithm are revealed to play important roles in producing 1/f1/f fluctuations at the critical point.Comment: 14 pages, 9 figures. To appear physica

    Cocktail δ-integration: a novel method to construct cellulolytic enzyme expression ratio-optimized yeast strains

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    <p>Abstract</p> <p>Background</p> <p>The filamentous fungus <it>T. reesei </it>effectively degrades cellulose and is known to produce various cellulolytic enzymes such as β-glucosidase, endoglucanase, and cellobiohydrolase. The expression levels of each cellulase are controlled simultaneously, and their ratios and synergetic effects are important for effective cellulose degradation. However, in recombinant <it>Saccharomyces cerevisiae</it>, it is difficult to simultaneously control many different enzymes. To construct engineered yeast with efficient cellulose degradation, we developed a simple method to optimize cellulase expression levels, named cocktail δ-integration.</p> <p>Results</p> <p>In cocktail δ-integration, several kinds of cellulase expression cassettes are integrated into yeast chromosomes simultaneously in one step, and strains with high cellulolytic activity (i.e., expressing an optimum ratio of cellulases) are easily obtained. Although the total integrated gene copy numbers of cocktail δ-integrant strain was about half that of a conventional δ-integrant strain, the phosphoric acid swollen cellulose (PASC) degradation activity (64.9 mU/g-wet cell) was higher than that of a conventional strain (57.6 mU/g-wet cell). This suggests that optimization of the cellulase expression ratio improves PASC degradation activity more so than overexpression.</p> <p>Conclusions</p> <p>To our knowledge, this is the first report on the expression of cellulase genes by δ-integration and optimization of various foreign genes by δ-integration in yeast. This method should be very effective and easily applied for other multi-enzymatic systems using recombinant yeast.</p

    Learning Algorithm for a Brachiating Robot

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    If charity begins at home, scholarship on the charitable deduction has stayed at home. In the vast legal literature, few authors have engaged the distinction between charitable contributions that are meant to be used within the United States and charitable contributions that are meant to be used abroad. Yet these two types of contributions are treated very differently in the Code and raise very different policy issues. As Americans\u27 giving patterns and the U.S. nonprofit sector grow increasingly international, the distinction will only become more salient. This Article offers the first exploration of how theories of the charitable deduction apply to internationally targeted donations. In so doing, the Article aims to contribute not only to a methodological shift in nonprofit tax scholarship (a strategic remapping), but also to a reappraisal of the deduction literature (an analytic remapping): just as existing theories of the deduction can inform our understanding of foreign charity, considerations of foreign charity can shed light back on the existing theories. I argue that the standard rationales are underdetermined and undertheorized, and propose a new, integrated approach to the charitable deduction. Internationally targeted donations emerge from the analysis holding a strong claim to deductibility – often a stronger claim than domestically targeted donations hold – on almost every relevant dimension, which calls into question current regulations that privilege domestic giving. Oversight and foreign policy concerns, however, complicate the ideal of geographic neutrality and illuminate the charitable deduction\u27s role as an instrument of statecraft. Admitting foreign charity into the debate over the deduction thus changes the debate\u27s terms; it gives deduction theory new urgency as well as new complexity

    Geographic Variation of Particle Size Distribution in the Kuroshio Region: Possible Causes in the Upper Water Column

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    Particle size distribution (PSD) in the ocean is a fundamental property that influences carbon export and food webs; however, PSD variation and its causes in oligotrophic oceans are not entirely clear. Here, we used Laser In-Situ Scattering and Transmissometry to investigate PSD (size range 5.2–119 μm) and related variables at 11 stations in the surface layer (0–20 m) of the Kuroshio region of the western North Pacific, where strong current causes dynamic hydrographic and ecological conditions. PSD slopes (range –3.2 to –4.2), derived from the power law model, were steeper at onshore stations and flatter at oligotrophic stations located offshore and at lower latitudes. Notably, slopes tended to become steeper with increasing chlorophyll a concentration, opposing the generally observed relationship between the two variables, whereas they became flatter with increasing transparent exopolymer particle (TEP) concentration. Possible explanations of the above results are localized occurrence of nanophytoplankton and TEP facilitation of particle aggregation. The results support the hypothesis that PSD slopes are controlled by a multitude of factors, including phytoplankton community dynamics and aggregation processes. To determine whether TEP-induced particle aggregation enhances or suppresses carbon export, we need a better understanding of the nature (porosity, density, and sinking velocity) of aggregates in oligotrophic oceans

    Diagnosis of Temporomandibular Joint Arthrosis 1. Arthrographic Differentiation

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    Arthrotomography of the temporomandibular joint was performed on 207 joints of 148 patients by puncturing inferior and superior joint compartments and injecting water-soluble contrast medium under fluoroscopy. Symptoms of these subjects were arthralgia, noise and hypomobility of the temporomandibular joint. In the results, 16 joints (7.7%) were normal, 31 joints (15.0%) with reducible anterior disk displacement (click), 143 joints (69.1%) with non-reducible anterior disk displacement (closed-lock), and 17 joints (8.2%) with stenosis or adhesion of the joint compartment. Among the all joints, 13 joints (6.3%) associated with discal perforation. These findings indicated several intra-capsular organic changes, moreover has a significance in differential diagnosis and treatment for the patients with temporomandibular joint arthrosis

    Renal Oncocytoma Associated With Long-Term Hemodialysis

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    A 50-year old woman was admitted to our hospital for further evaluation of the right renal tumor. She had been on maintenance hemodialysis for 12 years. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a large right renal tumor. There was no central stellate scar. Angiography showed hypervascularity and tumor staining . With the pre-operative diagnosis of renal cell carcinoma, right nephrectomy was performed. The pathological diagnosis was renal oncocytoma
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