478 research outputs found

    Historical delta(15) N records of Saccharina specimens from oligotrophic waters of Japan Sea (Hokkaido)

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    Historically Saccharina spp. beds occurred along the west coast of Hokkaido, an oligotrophic area, and were commercially exploited. Currently extensive commercial Saccharina spp. beds do not form due to nutrient limitations. Here, we postulate that nutrients assimilated by paleo-Saccharina spp. beds may have been derived from spawning herrings (Clupea pallasii) acting as organisms that formed a vector from their feeding grounds (Okhotsk Sea and Pacific Ocean) to their spawning area (west coast of Hokkaido, Japan Sea). To test this hypothesis we examined stable nitrogen isotope ratios (delta N-15) of 100-to 135-year-old Saccharina specimens preserved at the Herbarium (Hokkaido University Museum). delta(15) N values of the paleo-Saccharina specimens collected from this region were in the range of 10%, which is significantly higher than the current 3-7% in freshly sampled Saccharina spp. This high delta(15) N indicates that spawning herring (Clupea pallasii) had potentially been a significant source of dissolved inorganic nitrogen (DIN) absorbed by Saccharina, acting as an organism forming a vector for transporting nutrients from eutrophic to oligotrophic coastal ecosystems. Our findings support the hypothesis of so-called "herring-derived nutrients

    Black-Box Anomaly Attribution

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    When the prediction of a black-box machine learning model deviates from the true observation, what can be said about the reason behind that deviation? This is a fundamental and ubiquitous question that the end user in a business or industrial AI application often asks. The deviation may be due to a sub-optimal black-box model, or it may be simply because the sample in question is an outlier. In either case, one would ideally wish to obtain some form of attribution score -- a value indicative of the extent to which an input variable is responsible for the anomaly. In the present paper we address this task of ``anomaly attribution,'' particularly in the setting in which the model is black-box and the training data are not available. Specifically, we propose a novel likelihood-based attribution framework we call the ``likelihood compensation (LC),'' in which the responsibility score is equated with the correction on each input variable needed to attain the highest possible likelihood. We begin by showing formally why mainstream model-agnostic explanation methods, such as the local linear surrogate modeling and Shapley values, are not designed to explain anomalies. In particular, we show that they are ``deviation-agnostic,'' namely, that their explanations are blind to the fact that there is a deviation in the model prediction for the sample of interest. We do this by positioning these existing methods under the unified umbrella of a function family we call the ``integrated gradient family.'' We validate the effectiveness of the proposed LC approach using publicly available data sets. We also conduct a case study with a real-world building energy prediction task and confirm its usefulness in practice based on expert feedback

    Growth of Massive Molecular Cloud Filament by Accretion Flows I: Slow Shock Instability v.s. Ambipolar Diffusion

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    The Herschel Gould Belt Survey showed that stars form in dense filaments in nearby molecular clouds. Recent studies suggest that massive filaments are bound by the slow shocks caused by accretion flows onto the filaments. The slow shock is known to be unstable to the corrugation deformation of the shock front. The corrugation instability could convert the accretion flow's ram pressure into turbulent pressure that influences the width of the filament, which, according to theory, determines the self-gravitational fragmentation scale and core mass. In spite of its importance, the effect of slow shock instability on star-forming filaments has not been investigated. In addition, the linear dispersion relation obtained from the ideal magnetohydrodynamics (MHD) analysis shows that the most unstable wavelength of shock corrugation is infinitesimally small (or mean free path). In the scale of dense filaments, the effect of ambipolar diffusion can suppress the instability at small scales. This study investigates the influence of ambipolar diffusion on the instability of the slow shock. We perform two-dimensional MHD simulations to examine the linear growth of the slow shock instability, considering the effect of ambipolar diffusion. The results demonstrate that the most unstable scale of slow shock instability is approximately five times the length scale of ambipolar diffusion l_AD calculated using post-shock variables, where, l_AD corresponds to the scale where the magnetic Reynolds number for ambipolar diffusivity is unity.Comment: 20 pages, 12 figures, accepted by Ap

    Targeted Advertising on Social Networks Using Online Variational Tensor Regression

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    This paper is concerned with online targeted advertising on social networks. The main technical task we address is to estimate the activation probability for user pairs, which quantifies the influence one user may have on another towards purchasing decisions. This is a challenging task because one marketing episode typically involves a multitude of marketing campaigns/strategies of different products for highly diverse customers. In this paper, we propose what we believe is the first tensor-based contextual bandit framework for online targeted advertising. The proposed framework is designed to accommodate any number of feature vectors in the form of multi-mode tensor, thereby enabling to capture the heterogeneity that may exist over user preferences, products, and campaign strategies in a unified manner. To handle inter-dependency of tensor modes, we introduce an online variational algorithm with a mean-field approximation. We empirically confirm that the proposed TensorUCB algorithm achieves a significant improvement in influence maximization tasks over the benchmarks, which is attributable to its capability of capturing the user-product heterogeneity.Comment: 18 pages, 7 figure

    Anomaly Attribution with Likelihood Compensation

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    This paper addresses the task of explaining anomalous predictions of a black-box regression model. When using a black-box model, such as one to predict building energy consumption from many sensor measurements, we often have a situation where some observed samples may significantly deviate from their prediction. It may be due to a sub-optimal black-box model, or simply because those samples are outliers. In either case, one would ideally want to compute a ``responsibility score'' indicative of the extent to which an input variable is responsible for the anomalous output. In this work, we formalize this task as a statistical inverse problem: Given model deviation from the expected value, infer the responsibility score of each of the input variables. We propose a new method called likelihood compensation (LC), which is founded on the likelihood principle and computes a correction to each input variable. To the best of our knowledge, this is the first principled framework that computes a responsibility score for real valued anomalous model deviations. We apply our approach to a real-world building energy prediction task and confirm its utility based on expert feedback.Comment: 8 pages, 7 figure

    Consideration for fractional slot winding of permanent magnet type synchronous machine

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    Fractional Winding is used for permanent magnet type synchronous machine to improve the EMF form and cogging etc. This paper report the characteristics of q=1/2 and q=3/8 (q<0.5) especially. And the mixed coils in each phase winding we called, can give the flexibility of winding design. We report the advantages of this winging method with theory and measured data.2011 International Conference on Electrical Machines and Systems, ICEMS 2011; Beijing; 20 August 2011 through 23 August 201

    Teanol, a new brominated sesquiterpene from the Thailand Laurencia mariannensis

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    We examined the constitution of Laurencia mariannensis collected from the east coast of Tean Island, Thailand. The structure of a new brominated rearranged cyclolaurane-type sesquiterpene, named teanol (1), is reported. This is the first report on biology and chemistry of the Thailand red algal genus Laurencia (Rhodomelaceae, Ceramiales)

    Current Spike Reduction Technique for High Power Laser Diode Driver with Pulse Current Output

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    A Vertical-Cavity Surface-Emitting Laser (VCSEL) has attracted a strong interest as a pump source of diode pumped solid state (DPSS) lasers for many applications, such as welding, cutting and marking, in recent years. In the past, a series dropper has been typically used as a laser driver. However, the power loss of series dropper which adopts several kW class high power laser is very large, and the cooling system becomes much larger and whole driver is also much larger. In order to solve these problems, switch mode power supply (SMPS) is adopted as a laser driver. However, switch device breakdown problem occurs in this case. This paper clarifies the mechanism of mentioned above problem and proposes the solution technique.2017 IEEE 12th International Conference on Power Electronics & Drive Systems, Hawaii convention center, Honolulu, USA, 12-15 December 201

    ルテニウム(III)金属錯体を用いたホスビチンのボルタンメトリー的センシング

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    Voltammetric sensing of phosvitin was carried out based on an interaction between ruthenium(III) and phosvitin. The electrode response of hexaammineruthenium(III) was measured using a glassy carbon electrode. When phosvitin was added to 0.1 M phosphate buffer (pH 7.0) containing hexaammineruthenium(III), a new peak was observed due to the formation of ruthenium (III)-phosvitin complex. On the other hand, it was expected that iron strongly combines with phosphate groups of phosvitin. Although a new peak did not appear in the incubation of hexacyanoferrate(III) and phosvitin, the peak current of hexacyanoferrate(III) decreased as the concentration of phosvitin increased. The electrode responses of hexaammineruthenium(III) and hexacyanoferrate(III) were linear and ranged from 2.5 x 10-10-5.0 x 10-9M and 5.0 x10-8-5.0 x 10-7M, respectively. As a result, the interaction between hexaammineruthenium(III) and phosvitin was stronger than that between hexacyanoferrate(III) and phosvitin. The decrease of the peak current with phosphoprotein such as ovalbumin and casein was observed. The change of the electrode response with phosvitin was the greatest in those proteins. Consequently, the sensing system had a high selectivity for phosvitin

    Fundamental characteristics of a novel self-starting type permanent magnet synchronous motor

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    Wide use of permanent magnet synchronous motors produces a request for adding self-starting function to them. We propose a squirrel-cage rotor with permanent magnets for the self-starting synchronous motors. This paper shows the rotor configuration of a proposed motor and investigates the fundamental characteristics associated with the self-starting function.15th International Conference on Electrical Machines and Systems, ICEMS 2012; Sapporo; Japan; 21 October 2012 ~ 24 October 201
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