53 research outputs found

    A Covariate-Adjusted Homogeneity Test with Application to Facial Recognition Accuracy Assessment

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    Ordinal scores occur commonly in medical imaging studies and in black-box forensic studies \citep{Phillips:2018}. To assess the accuracy of raters in the studies, one needs to estimate the receiver operating characteristic (ROC) curve while accounting for covariates of raters. In this paper, we propose a covariate-adjusted homogeneity test to determine differences in accuracy among multiple rater groups. We derived the theoretical results of the proposed test and conducted extensive simulation studies to evaluate the finite sample performance of the proposed test. Our proposed test is applied to a face recognition study to identify statistically significant differences among five participant groups

    Retrieval of interatomic separations of molecules from laser-induced high-order harmonic spectra

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    We illustrate an iterative method for retrieving the internuclear separations of N2_2, O2_2 and CO2_2 molecules using the high-order harmonics generated from these molecules by intense infrared laser pulses. We show that accurate results can be retrieved with a small set of harmonics and with one or few alignment angles of the molecules. For linear molecules the internuclear separations can also be retrieved from harmonics generated using isotropically distributed molecules. By extracting the transition dipole moment from the high-order harmonic spectra, we further demonstrated that it is preferable to retrieve the interatomic separation iteratively by fitting the extracted dipole moment. Our results show that time-resolved chemical imaging of molecules using infrared laser pulses with femtosecond temporal resolutions is possible.Comment: 14 pages, 9 figure

    Recommendation Systems: A Systematic Review

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    This article presents a comprehensive and objective systematic review of existing research on recommendation systems with regards to core theory, latest studies, various applications, current attitudes, and potential future applications. The research is mainly based on exploring professional peer-reviewed studies and articles and using their abstracts to create a comprehensive and unbiased review of existing research. The following search terms were used to identify articles and studies for the research: recommendation systems; recommender systems; core theory of recommender systems; current attitudes towards recommendation systems; latest studies on recommendation systems; applications of recommendation systems; potential studies on recommendation systems; and future potential applications of recommendation systems. The research also used the advanced search filter to locate recent studies for comparison by limiting the search by year to find studies published from 2021 onwards. Most literature on this area highlights the importance of recommendation systems in almost all aspects of modern life. Specifically, recommendation systems have become critical components in business, health care, education, marketing, and social networking domains. Additionally, most studies identified reinforcement of learning and deep learning techniques as significant developments in the field. These techniques form the backbone of most modern recommendation systems. The primary concern that could hinder further evolution systems is their consequent filter bubble effects which many studies showed to be problematic. Healthcare is a central area that shows tremendous potential for these systems. Although recommender systems have been implemented in this domain, there remains a lot of untapped potential that, if unleashed, could revolutionize medicine and healthcare. But the problems facing these systems have to be tackled first to establish trust. Keywords: Recommendation systems, Recommender systems, Deep learning, Reinforcement learning DOI: 10.7176/CEIS/13-4-04 Publication date:August 31st 202

    Kognitivne perspektive, inovativnost i konkurentska prednost stratega: empirijska studija u Vijetnamu

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    The main aim of this study is to investigate the relationship between strategists’ intuitive and analytical thinking, innovation, and corporate competitive advantage. This study not only proposes the new model to the academic world but also provides the empirical investigation on the direct and indirect effect of a strategist’s analytic reasoning perspective and strategist’s generative reasoning perspective on innovation and competitive advantage as well as the mediating role of innovation between the strategist’s cognitive perspective of reasoning and corporate competitive advantage. This study conducted questionnaires of 382 samples in state-owned companies, FDI, and private companies in Vietnam. Structure equation modelling was applied through smart PLS to analyse the valid data. The results provide substantial evidence of significant relationships between strategists’ cognitive perspectives of reasoning, innovation, and competitive advantage in the context of State own, FDI, and private companies in Vietnam. Besides, the findings also show that there are non-relationships in the direct effect between product innovation and competitive advantage and between marketing innovation and competitive advantage. Moreover, the research results imply various managerial implications regarding how organizations successfully increase their competitive advantage by increasing their leader’s cognition in management.Glavni cilj ove studije je istražiti odnos između intuitivnog i analitičkog razmišljanja stratega, inovativnosti i konkurentske prednosti poduzeća. Ova studija ne samo da predlaže novi model akademskom svijetu, već također pruža empirijsko istraživanje izravnog i neizravnog učinka analitičke perspektive razmišljanja stratega i perspektive generativnog razmišljanja stratega o inovacijama i konkurentskoj prednosti, kao i o posredničkoj ulozi inovacije između kognitivne perspektive razmišljanja stratega i konkurentske prednosti poduzeća. Ovim istraživanjem provedena je anketa s 382 uzoraka u državnim tvrtkama, izravnim stranim ulaganjima i privatnim tvrtkama u Vijetnamu. Modeliranje strukturnih jednadžbi primijenjeno je putem pametnog PLS-a za analizu valjanih podataka. Rezultati pružaju bitne dokaze o značajnim odnosima između kognitivnih perspektiva razmišljanja, inovativnosti i konkurentske prednosti stratega u kontekstu državnih poduzeća, izravnih stranih ulaganja i privatnih tvrtki u Vijetnamu. Osim toga, nalazi također upućuju na ne postojanje veze s izravnom učinkom ni između inovacije proizvoda i konkurentske prednosti niti između marketinške inovacije i konkurentske prednosti. Štoviše, rezultati istraživanja upućuju na različite menadžerske implikacije o tome kako organizacije uspješno povećavaju svoju konkurentsku prednost povećanjem kognitivnih sposobnosti svog lidera u upravljanju

    Retrieving Molecular Structural Information and Tracking HNC/HCN Isomerization Process with High Harmonic Generation by Ultrashort Laser Pulses

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    We investigate the possibility of applying the iterative method,suggested in our previous work, for HCN molecule and its HNCisomer. We found that the high-order harmonic generation (HHG)spectra are quite insensitive to the change of H-C (or H-N) bondlength so that only the inter-nuclear C-N distance can beretrieved from the high-order harmonic spectra using ultrashortintense lasers. Furthermore, by analyzing the HHG spectra emittedby HCN during the chemical reaction path of isomerization weidentify the intensity peaks nearby the stable, meta-stable andtransition states. This finding can be useful for tracking theHNC/HCN isomerization process

    Probing and extracting the structure of vibrating SF 6 molecules with inner-shell photoelectrons

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    Citation: Nguyen, N. T., Lucchese, R. R., Lin, C. D., & Le, A. T. (2016). Probing and extracting the structure of vibrating SF6 molecules with inner-shell photoelectrons. Physical Review A, 93(6), 9. doi:10.1103/PhysRevA.93.063419We propose a scheme for probing the structure of vibrating molecules with photoelectrons generated from ultrashort soft-x-ray pulses. As an example we analyze below-100-eV photoelectrons liberated from the S(2p) orbital of vibrating SF6 molecules to image very small structural changes of molecular vibration. In particular, photoionization cross sections and photoelectron angular distributions (PAD) at nonequilibrium geometries can be retrieved accurately with photoelectrons near the shape resonance at 13 eV. This is achieved with a pump-probe scheme, in which the symmetric stretch mode is first Raman excited predominantly by a relatively short laser pulse and then later probed at different time delays by a few-femtosecond soft-x-ray pulse with photon energy near 200 eV

    Antibiotic use and prescription and its effects on Enterobacteriaceae in the gut in children with mild respiratory infections in Ho Chi Minh City, Vietnam. A prospective observational outpatient study.

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    BACKGROUND AND OBJECTIVES: Treatment guidelines do not recommend antibiotic use for acute respiratory infections (ARI), except for streptococcal pharyngitis/tonsillitis and pneumonia. However, antibiotics are prescribed frequently for children with ARI, often in absence of evidence for bacterial infection. The objectives of this study were 1) to assess the appropriateness of antibiotic prescriptions for mild ARI in paediatric outpatients in relation to available guidelines and detected pathogens, 2) to assess antibiotic use on presentation using questionnaires and detection in urine 3) to assess the carriage rates and proportions of resistant intestinal Enterobacteriaceae before, during and after consultation. MATERIALS AND METHODS: Patients were prospectively enrolled in Children's Hospital 1, Ho Chi Minh City, Vietnam and diagnoses, prescribed therapy and outcome were recorded on first visit and on follow-up after 7 days. Respiratory bacterial and viral pathogens were detected using molecular assays. Antibiotic use before presentation was assessed using questionnaires and urine HPLC. The impact of antibiotic usage on intestinal Enterobacteriaceae was assessed with semi-quantitative culture on agar with and without antibiotics on presentation and after 7 and 28 days. RESULTS: A total of 563 patients were enrolled between February 2009 and February 2010. Antibiotics were prescribed for all except 2 of 563 patients. The majority were 2nd and 3rd generation oral cephalosporins and amoxicillin with or without clavulanic acid. Respiratory viruses were detected in respiratory specimens of 72.5% of patients. Antibiotic use was considered inappropriate in 90.1% and 67.5%, based on guidelines and detected pathogens, respectively. On presentation parents reported antibiotic use for 22% of patients, 41% of parents did not know and 37% denied antibiotic use. Among these three groups, six commonly used antibiotics were detected with HPLC in patients' urine in 49%, 40% and 14%, respectively. Temporary selection of 3rd generation cephalosporin resistant intestinal Enterobacteriaceae during antibiotic use was observed, with co-selection of resistance to aminoglycosides and fluoroquinolones. CONCLUSIONS: We report overuse and overprescription of antibiotics for uncomplicated ARI with selection of resistant intestinal Enterobacteriaceae, posing a risk for community transmission and persistence in a setting of a highly granular healthcare system and unrestricted access to antibiotics through private pharmacies. REGISTRATION: This study was registered at the International Standard Randomised Controlled Trials Number registry under number ISRCTN32862422: http://www.isrctn.com/ISRCTN32862422

    Diagnostic Accuracy of NS1 ELISA and Lateral Flow Rapid Tests for Dengue Sensitivity, Specificity and Relationship to Viraemia and Antibody Responses

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    Dengue is a viral infection of humans that is transmitted by mosquitoes. Dengue is a very important public health problem in many developing countries. Recently, new tests to help diagnose patients with dengue have been developed. Evaluating these tests to see how well they perform in different countries and in different health care settings is an important process that helps to guide health care policy on whether these assays are likely to be useful in making a diagnosis, and if so, when best to use them. Our hospital-based results, using two different types of NS1 tests for diagnosing dengue, indicates that these tests are most sensitive when used during the first 3 days of illness and are most likely to be positive if the patient has primary dengue. Our results also show that a positive NS1 test result is a reflection of the amount of virus in the blood, so that patients with high amounts of virus in the blood are more likely to be NS1 positive. Collectively, the results indicate these NS1 tests deserve inclusion in the diagnostic approach to dengue

    Kinetics of Plasma Viremia and Soluble Nonstructural Protein 1 Concentrations in Dengue: Differential Effects According to Serotype and Immune Status

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    We describe the magnitude and kinetics of plasma viremia and nonstructural protein 1 (sNS1) levels in sequential samples from 167 children with acute dengue, enrolled early in a community study in Vietnam. All children recovered fully, and only 5 required hospitalization. Among those with dengue virus type 1 (DENV-1), plasma viremia was significantly greater in primary (49) than secondary (44) infections and took longer to resolve. In primary DENV-2 and 3 infections, viremia was significantly lower than among primary DENV-1 infections. Concentrations of sNS1 were significantly higher for DENV-1 than for DENV-2 after adjusting for viremia, with marked differences in the kinetic profiles between primary and secondary infections. Secondary infection and higher viremia were independent predictors of more severe thrombocytopenia, and higher viremia was associated with a small increase in hemoconcentration. Our findings identify clear serotype and immune-status related effects on the dynamics of dengue viremia and sNS1 responses, together with associations with important clinical parameters
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