528 research outputs found

    Proper Learning Algorithm for Functions of k Terms under Smooth Distributions

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    AbstractIn this paper, we introduce a probabilistic distribution, called a smooth distribution, which is a generalization of variants of the uniform distribution such as q-bounded distribution and product distribution. Then, we give an algorithm that, under the smooth distribution, properly learns the class of functions of k terms given as Fk∘Tkn={g(f1(v), …, fk(v))|g∈Fk, f1, …, fk∈Tn} in polynomial time for constant k, where Fk is the class of all Boolean functions of k variables and Tn is the class of terms over n variables. Although class Fk∘Tkn was shown by Blum and Singh to be learned using DNF as the hypothesis class, it has remained open whether it is properly learnable under a distribution-free setting

    Extracellular ATP/adenosine dynamics in the brain and its role in health and disease

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    Extracellular ATP and adenosine are neuromodulators that regulate numerous neuronal functions in the brain. Neuronal activity and brain insults such as ischemic and traumatic injury upregulate these neuromodulators, which exert their effects by activating purinergic receptors. In addition, extracellular ATP/adenosine signaling plays a pivotal role in the pathogenesis of neurological diseases. Virtually every cell type in the brain contributes to the elevation of ATP/adenosine, and various mechanisms underlying this increase have been proposed. Extracellular adenosine is thought to be mainly produced via the degradation of extracellular ATP. However, adenosine is also released from neurons and glia in the brain. Therefore, the regulation of extracellular ATP/adenosine in physiological and pathophysiological conditions is likely far more complex than previously thought. To elucidate the complex mechanisms that regulate extracellular ATP/adenosine levels, accurate methods of assessing their spatiotemporal dynamics are needed. Several novel techniques for acquiring spatiotemporal information on extracellular ATP/adenosine, including fluorescent sensors, have been developed and have started to reveal the mechanisms underlying the release, uptake and degradation of ATP/adenosine. Here, we review methods for analyzing extracellular ATP/adenosine dynamics as well as the current state of knowledge on the spatiotemporal dynamics of ATP/adenosine in the brain. We focus on the mechanisms used by neurons and glia to cooperatively produce the activity-dependent increase in ATP/adenosine and its physiological and pathophysiological significance in the brain

    Rapid modification of antibodies on the surface of liposomes composed of high-affinity protein A-conjugated phospholipid for selective drug delivery

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    Antibody-modified liposomes, immuno-liposomes, can selectively deliver encapsulated drug ‘cargos’ to cells via the interaction of cell surface proteins with antibodies. However, chemical modification of both the antibodies and phospholipids is required for the preparation of immuno-liposomes for each target protein using conventional methods, which is time-consuming. In the present study, we demonstrated that high-affinity protein A- (Protein A-R28: PAR28) displaying liposomes prepared by the post-insertion of PAR28-conjugated phospholipid through polyethylene glycol (PEG)-linkers (PAR28-PEG-lipo) can undergo rapid modification of antibodies on their surface, and the liposomes can be delivered to cells based on their modified antibodies. Anti-CD147 and anti-CD31 antibodies could be modified with PAR28-PEG-lipo within 1 h, and each liposome was specifically taken up by CD147- and CD31-positive cells, respectively. The cellular amounts of doxorubicin delivered by anti-CD147 antibody-modified PAR28-PEG-lipo were significantly higher than those of isotype control antibody-modified liposomes. PAR28-PEG-lipo can easily and rapidly undergo modification of various antibodies on their surface, which then makes them capable of selective drug delivery dependent on the antibodies

    Kinematics of the Tined Combine Harvester Reel

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    Although derivation of the kinematic equations of the combine harvester reel is readily achieved, certain inferences thereof suggest possible improvements in its kinematical design.  A mathematically computed reference value of the reel index (ratio of the product of the reel radius and rotational velocity to the reel advance velocity) is found to be larger than commonly recommended values.  The point, either spatial or temporal, within the cycle of reel motion, at which the tinebar should preferably enter the crop is discussed.  The pick-up performance of the tines is qualitatively analyzed and its possible improvement through redesign of reel tine kinematics is suggested. Keywords: combine harvester reel, reel kinematics, tine trajectory

    Modeling of crop stem deflection in the context of combine harvester reel design and operation

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    A model of crop stem deflection by the combine harvester reel is formulated.  The equations derived thereof are evaluated on the basis of empirical data that were acquired through deflection of crop stems in a ready-for-harvest Japonica rice in the field.  The empirical data are found to be in agreement with the theoretically derived equations. Applications of crop stem deflection to reel design and operation are discussed.  The derived crop stem deflection model should be applicable in other situations in which it becomes necessary to study the deflection of crop stems, particularly in the domain of agricultural machinery engineering. Keywords: combine harvester header, tined reel, crop stem deflection, rice crop, mathematical modeling, model validation, model applicatio

    Impact of neoadjuvant chemotherapy on physical fitness, physical activity, and health-related quality of life of patients with resectable esophageal cancer.

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    Neoadjuvant chemotherapy (NAC) followed by radical surgery is the standard treatment for patients with resectable esophageal squamous cell carcinoma (ESCC) in Japan. However, some adverse events associated with NAC may result in a decrease in physical fitness that may influence the patient's ability to tolerate surgery. The purpose of this study was to evaluate the impact of NAC on physical fitness, physical activity, and health-related quality of life (HRQOL) of patients with ESCC
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