29 research outputs found

    Economics of Spot Instance Service: A Two-stage Dynamic Game Apporach

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    This paper presents the economic impacts of spot instance service on the cloud service providers (CSPs) and the customers when the CSPs offer it along with the on-demand instance service to the customers. We model the interaction between CSPs and customers as a non-cooperative two-stage dynamic game. Our equilibrium analysis reveals (i) the techno-economic interrelationship between the customers' heterogeneity, resource availability, and CSPs' pricing policy, and (ii) the impacts of the customers' service selection (spot vs. on-demand) and the CSPs' pricing decision on the CSPs' market share and revenue, as well as the customers' utility. The key technical challenges lie in, first, how we capture the strategic interactions between CSPs and customers, and second, how we consider the various practical aspects of cloud services, such as heterogeneity of customers' willingness to pay for the quality of service (QoS) and the fluctuating resource availability. The main contribution of this paper is to provide CSPs and customers with a better understanding of the economic impact caused by a certain price policy for the spot service when the equilibrium price, which from our two-stage dynamic game analysis, is able to set as the baseline price for their spot service

    Utilization of a combined EEG/NIRS system to predict driver drowsiness

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    The large number of automobile accidents due to driver drowsiness is a critical concern of many countries. To solve this problem, numerous methods of countermeasure have been proposed. However, the results were unsatisfactory due to inadequate accuracy of drowsiness detection. In this study, we introduce a new approach, a combination of EEG and NIRS, to detect driver drowsiness. EEG, EOG, ECG and NIRS signals have been measured during a simulated driving task, in which subjects underwent both awake and drowsy states. The blinking rate, eye closure, heart rate, alpha and beta band power were used to identify subject’s condition. Statistical tests were performed on EEG and NIRS signals to find the most informative parameters. Fisher’s linear discriminant analysis method was employed to classify awake and drowsy states. Time series analysis was used to predict drowsiness. The oxy-hemoglobin concentration change and the beta band power in the frontal lobe were found to differ the most between the two states. In addition, these two parameters correspond well to an awake to drowsy state transition. A sharp increase of the oxy-hemoglobin concentration change, together with a dramatic decrease of the beta band power, happened several seconds before the first eye closure

    Herbal Extracts That Reduce Ocular Oxidative Stress May Enhance Attentive Performance in Humans

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    We used herbal extracts in this study to investigate the effects of blue-light-induced oxidative stress on subjects’ attentive performance, which is also associated with work performance. We employed an attention network test (ANT) to measure the subjects’ work performance indirectly and used herbal extracts to reduce ocular oxidative stress. Thirty-two subjects participated in either an experimental group (wearing glasses containing herbal extracts) or a control group (wearing glasses without herbal extracts). During the ANT experiment, we collected electroencephalography (EEG) and electrooculography (EOG) data and measured button responses. In addition, electrocardiogram (ECG) data were collected before and after the experiments. The EOG results showed that the experimental group exhibited a reduced number of eye blinks per second during the experiment and faster button responses with a smaller variation than did the control group; this group also showed relatively more sustained tension in their ECG results. In the EEG analysis, the experimental group had significantly greater cognitive processing, with larger P300 and parietal 2–6 Hz activity, an orienting effect with neural processing of frontal area, high beta activity in the occipital area, and an alpha and beta recovery process after the button response. We concluded that reducing blue-light-induced oxidative stress with herbal extracts may be associated with reducing the number of eye blinks and enhancing attentive performance

    Integrative web cloud computing and analytics using MiPair for design-based comparative analysis with paired microbiome data

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    Abstract Pairing (or blocking) is a design technique that is widely used in comparative microbiome studies to efficiently control for the effects of potential confounders (e.g., genetic, environmental, or behavioral factors). Some typical paired (block) designs for human microbiome studies are repeated measures designs that profile each subject’s microbiome twice (or more than twice) (1) for pre and post treatments to see the effects of a treatment on microbiome, or (2) for different organs of the body (e.g., gut, mouth, skin) to see the disparity in microbiome between (or across) body sites. Researchers have developed a sheer number of web-based tools for user-friendly microbiome data processing and analytics, though there is no web-based tool currently available for such paired microbiome studies. In this paper, we thus introduce an integrative web-based tool, named MiPair, for design-based comparative analysis with paired microbiome data. MiPair is a user-friendly web cloud service that is built with step-by-step data processing and analytic procedures for comparative analysis between (or across) groups or between baseline and other groups. MiPair employs parametric and non-parametric tests for complete or incomplete block designs to perform comparative analyses with respect to microbial ecology (alpha- and beta-diversity) and taxonomy (e.g., phylum, class, order, family, genus, species). We demonstrate its usage through an example clinical trial on the effects of antibiotics on gut microbiome. MiPair is an open-source software that can be run on our web server ( http://mipair.micloud.kr ) or on user’s computer ( https://github.com/yj7599/mipairgit )

    Regioregular polymers containing benzodithiophene and thienothiophene segments with different electron donating side chains for high-performance polymer solar cells

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    This study describes a systematic study on side chain effect in the poly(thieno[3,4-b]thiophene)benzo[1,2-b:4,5-b′]dithiophene (PTB) polymer series based regioregular polymers with D1-A-D2-A configuration, denoted as PTT-BDT(R1)-TT-BDT(R2). The synthesized three regioregular polymers employ the same conjugated backbone but with different side chains (R1, R2), P1; hexyldecyl thiophene (HD, R1) and ethylhexyl thiophene (EH, R2), P2; hexyldecyl thiophene (HD, R1) and ethylhexylthio thiophene (S-EH, R2), P3; hexyldecylthio thiophene (S-HD, R1) and ethylhexylthio thiophene (S-EH, R2). Introduction of different side chains influenced optical, electrochemical, molecular packing properties, and device performance. The P3 polymer with alkylthio thiophene groups as R1 and R2 showed much broader light absorption and lower HOMO level than other polymers with relatively less alkylthio thiophene groups. Furthermore, the P3 polymer exhibited favorable polymer orientation and short π-π stacking distance for efficient charge transport in the BHJ PSCs. The P3 based bulk-heterojunction (BHJ) polymer solar cell (PSC) showed an improved PCE of 7.20% while the P1 and P2 based BHJ PSC devices showed PCEs of 5.27% and 6.45%, respectively. This result, within our knowledge, is the highest record among BHJ PSCs based PTB polymer series composed of benzo[1,2-b:4,5-b']dithiophene (BDT) segment and non-fluorinated alkyl ester (COOR) side chain substituted thieno[3,4-b]thiophene (TT) segment. © 20181

    Herbal Formula, PM014, Attenuates Lung Inflammation in a Murine Model of Chronic Obstructive Pulmonary Disease

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    Chronic obstructive pulmonary disease (COPD), which is characterized by airway obstruction, leads to, as the two major forms of COPD, chronic bronchitis and emphysema. This study was conducted to evaluate the effects of herbal formula, PM014, in a murine model of COPD. Balb/c mice were treated once with each herb extract in PM014 or PM014 mixture via an oral injection. Lipopolysaccharide (LPS) or elastase/LPS were administrated to the mice to induce a disease that resembles COPD. PM014 treatment significantly attenuated the increased accumulation of immune cells in bronchoalveolar lavage fluid (BALF) compared to control mice. In addition, the TNF-α and IL-6 levels in BALF were decreased in the PM014 mice. Furthermore, histological analysis demonstrated that PM014 attenuated the hazardous effects of lung inflammation. These data suggest that PM014 exerts beneficial effects against forms of COPD such as lung inflammation

    Regioregular D-1-A-D-2-A Terpolymer with Controlled Thieno[3,4-b]thiophene Orientation for High-Efficiency Polymer Solar Cells Processed with Nonhalogenated Solvents

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    A regioregular D1-A-D2-A terpolymer PDTSTTBDT incorporating dithieno[3,2-b:2′,3′-d]silole (DTS, D1) and benzo[1,2-b:4,5-b]dithiophene (BDT, D2) units with perfectly controlled thieno[3,4-b]thiophene (TT, A) orientation was synthesized for the first time. The thermal, optical, and electrochemical properties of the regioregular PDTSTTBDT were characterized and compared with the random PDTSTTBDT without structural regioregularity. The regioregular PDTSTTBDT showed ideal optical bandgap (1.45 eV), lower lying HOMO energy level, and higher degree of crystallinity compared to the random PDTSTTBDT. Moreover, it exhibited excellent solubility in nonhalogenated solvents as well as halogenated solvents. The inverted bulk-heterojunction polymer solar cells (PSCs) based on the regioregular PDTSTTBDT and o-xylene process solvent showed a power conversion efficiency as high as 6.14%, which is 500% higher than the random PDTSTTBDT-based PSCs. It was found that the remarkable enhancement of photovoltaic performance in regioregular PDTSTTBDT-based PSCs is mainly due to improved light absorption, effective polymer ordering, and high charge carrier mobility. © 2016 American Chemical Society.
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