1,496 research outputs found

    Seismic Signatures of the 12C({\alpha}, {\gamma})16O Reaction Rate in White Dwarf Models with Overshooting

    Full text link
    We consider the combined effects that overshooting and the 12C({\alpha}, {\gamma})16O reaction rate have on variable white dwarf stellar models. We find that carbon-oxygen white dwarf models continue to yield pulsation signatures of the current experimental 12C({\alpha}, {\gamma})16O reaction rate probability distribution function when overshooting is included in the evolution. These signatures hold because the resonating mantle region, encompassing \simeq\,0.2\,\Msun\ in a typical \simeq\,0.6\,\Msun\ white dwarf model, still undergoes radiative helium burning during the evolution to a white dwarf. Our specific models show two potential low-order adiabatic g-modes, g2g_2 and g6g_6, that signalize the 12C({\alpha}, {\gamma})16O reaction rate probability distribution function. Both g-mode signatures induce average relative period shifts of ΔP/P=0.44%\Delta P/P = 0.44 \% and ΔP/P=1.33%\Delta P/P = 1.33\% for g2g_2 and g6g_6 respectively. We find that g6g_6 is a trapped mode, and the g2g_2 period signature is inversely proportional to the 12C({\alpha}, {\gamma})16O reaction rate. The g6g_6 period signature generally separates the slower and faster reaction rates, and has a maximum relative period shift of ΔP/P=3.45%\Delta P/P = 3.45\%. We conclude that low-order g-mode periods from carbon-oxygen white dwarfs may still serve as viable probes for the 12C({\alpha}, {\gamma})16O reaction rate probability distribution function when overshooting is included in the evolution.Comment: 18 pages, 10 total figures, 2 online interactive figures, zenodo data set link included. Accepted to the Astrophysical Journa

    Tourism Companies Assessment via Social Media Using Sentiment Analysis

    Get PDF
    ازدادت وسائل التواصل الاجتماعي بشكل كبير وواضح لانها وسيلة إعلام للمستخدمين للتعبير عن مشاعرهم من خلال آلاف المنشورات والتعليقات حول شركات السياحة. وبالتالي ، يصعب على السائح قراءة جميع التعليقات لتحديد ما إذا كانت تلك الآراء إيجابية أم سلبية لتقييم نجاح الشركة. في هذه البحث,تم استخدام التنقيب عن النص لتصنيف المشاعر من خلال جمع مراجعات اللهجة العراقية حول شركات السياحة من الفيس بوك لتحليلها باستخدام تحليل المشاعر لتتبع المشاعر الموجوده في المنشورات والتعليقات. ثم تم تصنيفها إلى تعليق إيجابي أو سلبي أو محايد باستخدام Naïve Bayes, Rough Set Theory , K-Nearest Neighbor. من بين 71 شركة سياحة عراقية وجدت أن 28٪ من هذه الشركات لديها تقييم جيد جدا ، و 26٪ من هذه الشركات لديها تقييم جيد ، و 31٪ من هذه الشركات لديها تقييم متوسط ​​، و 4٪ من هذه الشركات لديها تقييم مقبول و 11٪ من هذه الشركات لديها تقييم سيء. ساعدت النتائج التجريبية الشركات على تحسين عملها وبرامجها واستجابة كافية وسريعة لمتطلبات العملاءIn recent years, social media has been increasing widely and obviously as a media for users expressing their emotions and feelings through thousands of posts and comments related to tourism companies. As a consequence, it became difficult for tourists to read all the comments to determine whether these opinions are positive or negative to assess the success of a tourism company. In this paper, a modest model is proposed to assess e-tourism companies using Iraqi dialect reviews collected from Facebook. The reviews are analyzed using text mining techniques for sentiment classification. The generated sentiment words are classified into positive, negative and neutral comments by utilizing Rough Set Theory, Naïve Bayes and K-Nearest Neighbor methods. After experimental results, it was determined that out of 71 tested Iraqi tourism companies, 28% from these companies have very good assessment, 26% from these companies have good assessment, 31% from these companies have medium assessment, 4% from these companies have acceptance assessment and 11% from these companies have bad assessment. These results helped the companies to improve their work and programs responding sufficiently and quickly to customer demands

    Word matching using single closed contours for indexing handwritten historical documents

    Get PDF
    Effective indexing is crucial for providing convenient access to scanned versions of large collections of historically valuable handwritten manuscripts. Since traditional handwriting recognizers based on optical character recognition (OCR) do not perform well on historical documents, recently a holistic word recognition approach has gained in popularity as an attractive and more straightforward solution (Lavrenko et al. in proc. document Image Analysis for Libraries (DIAL’04), pp. 278–287, 2004). Such techniques attempt to recognize words based on scalar and profile-based features extracted from whole word images. In this paper, we propose a new approach to holistic word recognition for historical handwritten manuscripts based on matching word contours instead of whole images or word profiles. The new method consists of robust extraction of closed word contours and the application of an elastic contour matching technique proposed originally for general shapes (Adamek and O’Connor in IEEE Trans Circuits Syst Video Technol 5:2004). We demonstrate that multiscale contour-based descriptors can effectively capture intrinsic word features avoiding any segmentation of words into smaller subunits. Our experiments show a recognition accuracy of 83%, which considerably exceeds the performance of other systems reported in the literature

    Health-Related Quality of Life in patients with chronic hepatitis C receiving Sofosbuvir-Based Treatment, with and without Interferon: a prospective observational study in Egypt

    Get PDF
    Background: The Egyptian government introduced the first directly acting antivirals (DAAs) into Egypt through the government funded National Treatment Program. As yet, there has been no investigation into the effects of these new DAAs therapies on patient reported outcomes (PROs). This study aimed to (1) assess the PROs (health-related quality of life (HRQoL), mental health and perceived social support) of HCV patients receiving DAAs therapy prior, during and at the end of therapy; (2) evaluate PROs of Interferon-free (dual) users versus Interferon-containing (triple) users cross the three different time periods; and (3) identify the predictors of HRQoL of DAAs therapy users cross the three different time periods.  Methods: A prospective observational design was used. Patients with chronic HCV undergoing treatment following the Egyptian National Guidelines at one of the national treatment centers were approached. Data collection occurred in the period from February to October 2015. Data was collected at three time points: (1) baseline (time 0: T0), before initiating therapy); (2) 5/6 weeks after initiation of therapy (time 1 of therapy: T1) and at the end of the therapy (Time 2: T2). Four PROs questionnaires were utilized for data collection: (1) Multidimensional Scale of Perceived Social Support (MSPSS), (2) The Depression Anxiety Stress Scales (DASS-21), (3) the Liver Disease Symptom Index-2.0 (LDSI-2.0) for testing disease specific HRQoL and (4) the Center for Adherence Support Evaluation (CASE) Index, alongside the background data sheet.  Results: Sixty-two patients participated. There was a change in HRQoL, symptom experience and mental health across the three different time periods. HRQoL was impaired more after starting the course of therapy (T1) than at baseline (T0) and end of therapy (T2), z ≥ -2.04, p ≤ .04. Also, symptom experience deteriorated more during the treatment period than at the baseline, Z ≥ -1.97, p ≤ .04. Anxiety and stress were significantly higher during the treatment period than at the end of treatment. Perceived social support was significantly higher during the treatment period than at baseline and end of therapy, Z ≥ -2.27, p ≤.023. During the course of therapy, triple users were more likely to report poorer HRQoL and anxiety than dual users (p ≤ .04). By the end of therapy, the two arms of therapy had no significant differences in any of the PROs.  At baseline, the predictor model significantly (p=.000) explained 37.5% of the variation in the HRQoL prior to therapy. Depression was the main variable that contributed to (41.3%) predicting change in HRQoL prior to therapy. During therapy, the model significantly (p=.000) explained 76% of the variation in the HRQoL-T1. Stress-T1, body mass index (BMI)-T1 and HRQoL-T0 significantly and respectively predicted 44.4%, 46.5% and 31.1% of the variation in HRQoL-T1. At the end of therapy, the model significantly (p=.000) predicted 80.5% of the variation in the HRQoL-T2. HRQoL-T1 and anxiety-T2 significantly predicted 72.3% and 61.6% of the variation in HRQoL-T2.  Conclusions: Baseline HRQoL, depression and BMI should be systematically assessed before starting the antiviral therapy for early detection and the improvement of the impairment before the initiation of therapy. Anxiety should be frequently assessed and followed up through the course of antiviral therapy. The triple group required more nursing and practitioner attention due to increased anxiety levels and impaired HRQoL during the treatment therapy

    Effect of the Generalized Uncertainty Principle on Post-Inflation Preheating

    Get PDF
    We examine effects of the Generalized Uncertainty Principle, predicted by various theories of quantum gravity to replace the Heisenberg's uncertainty principle near the Planck scale, on post inflation preheating in cosmology, and show that it can predict either an increase or a decrease in parametric resonance and a corresponding change in particle production. Possible implications are considered.Comment: v1: 9 pages, revtex4, no figures, accepted for publication in JCAP; v2: one reference added and various cosmetic (but no physics) changes to match published versio

    Development of two reference materials for all trans-retinol, retinyl palmitate, α- and γ-tocopherol in milk powder and infant formula

    Get PDF
    AbstractVitamins are important food constituents that can be present in almost every foodstuff. Food quality and safety depends on food surveillance by reliable quantitative analysis enabled by appropriate quality control. Certified matrix reference materials are versatile tools to support quality assurance and control. However, in the case of vitamins, which are important in various foods, there is a lack of matrix reference materials. Two certified reference materials for the determination of all–trans-retinol, retinyl palmitate, and α- and γ-tocopherol in milk powder and infant formula have been developed by the National Institute of Standards, Egypt. This article presents the preparation, characterization, homogeneity, and stability testing as well as statistical treatment of data and certified value assignment. The assignment of the certified values and associated uncertainties in the prepared natural-matrix reference materials were based on the widely used approach of combining data from independent and reliable analytical methods

    Scraping SERPs for Archival Seeds: It Matters When You Start

    Full text link
    Event-based collections are often started with a web search, but the search results you find on Day 1 may not be the same as those you find on Day 7. In this paper, we consider collections that originate from extracting URIs (Uniform Resource Identifiers) from Search Engine Result Pages (SERPs). Specifically, we seek to provide insight about the retrievability of URIs of news stories found on Google, and to answer two main questions: first, can one "refind" the same URI of a news story (for the same query) from Google after a given time? Second, what is the probability of finding a story on Google over a given period of time? To answer these questions, we issued seven queries to Google every day for over seven months (2017-05-25 to 2018-01-12) and collected links from the first five SERPs to generate seven collections for each query. The queries represent public interest stories: "healthcare bill," "manchester bombing," "london terrorism," "trump russia," "travel ban," "hurricane harvey," and "hurricane irma." We tracked each URI in all collections over time to estimate the discoverability of URIs from the first five SERPs. Our results showed that the daily average rate at which stories were replaced on the default Google SERP ranged from 0.21 -0.54, and a weekly rate of 0.39 - 0.79, suggesting the fast replacement of older stories by newer stories. The probability of finding the same URI of a news story after one day from the initial appearance on the SERP ranged from 0.34 - 0.44. After a week, the probability of finding the same news stories diminishes rapidly to 0.01 - 0.11. Our findings suggest that due to the difficulty in retrieving the URIs of news stories from Google, collection building that originates from search engines should begin as soon as possible in order to capture the first stages of events, and should persist in order to capture the evolution of the events...Comment: This is an extended version of the ACM/IEEE Joint Conference on Digital Libraries (JCDL 2018) full paper: https://doi.org/10.1145/3197026.3197056. Some of the figure numbers have change

    A multiplex approach of MS, 1D-, and 2D-NMR metabolomicsin plant ontogeny A case study on Clusia minor L. organs (leaf, flower, fruit, and seed)

    Get PDF
    Introduction The genus Clusia L. is mostly recognised for the production of prenylated benzophenones and tocotrienol derivatives. Objectives The objective of this study was to map metabolome variation within Clusia minor organs at different developmental stages. Material and Methods In total 15 organs/stages (leaf, flower, fruit, and seed) were analysed by UPLC-MS and 1H- and heteronuclear multiple-bond correlation (HMBC)-NMR-based metabolomics. Results This work led to the assignment of 46 metabolites, belonging to organic acids(1), sugars(2) phenolic acids(1), flavonoids(3) prenylated xanthones(1) benzophenones(4) and tocotrienols(2). Multivariate data analyses explained the variability and classification of samples, highlighting chemical markers that discriminate each organ/stage. Leaves were found to be rich in 5-hydroxy-8-methyltocotrienol (8.5 μg/mg f.w.), while flowers were abundant in the polyprenylated benzophenone nemorosone with maximum level detected in the fully mature flower bud (43 μg/mg f.w.). Nemorosone and 5-hydroxy tocotrienoloic acid were isolated from FL6 for full structural characterisation. This is the first report of the NMR assignments of 5-hydroxy tocotrienoloic acid, and its maximum level was detected in the mature fruit at 50 μg/mg f.w. Seeds as typical storage organ were rich in sugars and omega-6 fatty acids. Conclusion To the best of our knowledge, this is the first report on a comparative 1D-/2D-NMR approach to assess compositional differences in ontogeny studies compared with LC-MS exemplified by Clusia organs. Results derived from this study provide better understanding of the stages at which maximal production of natural compounds occur and elucidate in which developmental stages the enzymes responsible for the production of such metabolites are preferentially expressed

    Temperature dependence of J–V and C–V characteristics of n-InAs/p-GaAs heterojunctions prepared by flash evaporation technique and liquid phase epitaxy

    Get PDF
    In this work, n-type of InAs films have been successfully fabricated on p-GaAs monocrystalline substrates by both flash evaporation technique and liquid phase epitaxy. The elemental composition of the prepared films has been confirmed by energy dispersive X-ray (EDX) spectroscopy. The morphology of the films has been characterized by scanning electron microscopy (SEM). The current transport mechanisms of n-InAs/p-GaAs heterojunctions in the temperature range 300-400 K have been investigated. Temperature-dependent dark current density-voltage (J–V) studies under forward and reverse bias have been carried out for this purpose. In the temperature range studied, the dark current contribution in the low bias range is believed to be due to the generation-recombination of minority carriers in the space-charge region. A change in the preparation technique does not seem to have altered the dark current conduction mechanism. Capacitance-voltage (C–V) at various temperatures has been measured to identify the junction type as well as determination of the important junction parameters
    corecore