2,507 research outputs found

    WHEN PRIVACY PROCLIVITY MEET COVID-19: NO LONGER CONCERNS OF TODAY’S M-COMMERCE USERS?

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    This is continuous research of our previous publication (Thomas et al., 2021). A new two by two study (Before and After COVID 19) X (China and the US culture) was designed to test the moderated mediation effect of the COVID pandemic on M-commerce user’s privacy proclivity, trust, and M-commerce intention! A new sample was collected from two countries in different time periods (Before and after COVID pandemic) to investigate whether M-commerce users’ concern about privacy proclivity has changed after COVID-19. Built on top of our 2021 publication, this study discovered that privacy proclivity no longer has a significant direct impact on consumers’ M-commerce intentions after COVID, as consumers’ desires for convenience outweigh their privacy risk concerns. However, privacy proclivity still has significant influence on consumers’ M-commerce Trust, therefore, it has an indirect impact on M-commerce intentions, but the impact is limited. Finally, the results from Hayes’ PROCESS replicated our previous study findings that culture plays a moderating role in the relationship between privacy proclivity and m-commerce trust after COVID-19 outbreak (Thomas et al., 2021). The impact of privacy proclivity is stronger on M-commerce Trust in China than in the US

    Variations of the ISM Compactness Across the Main Sequence of Star-Forming Galaxies: Observations and Simulations

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    (abridged) The majority of star-forming galaxies follow a simple empirical correlation in the star formation rate (SFR) versus stellar mass (M∗M_*) plane, usually referred to as the star formation Main Sequence (MS). Here we combine a set of hydro-dynamical simulations of interacting galactic disks with state-of-the-art radiative transfer codes to analyze how the evolution of mergers is reflected upon the properties of the MS. We present \textsc{Chiburst}, a Markov Chain Monte Carlo (MCMC) Spectral Energy Distribution (SED) code that fits the multi-wavelength, broad-band photometry of galaxies and derives stellar masses, star formation rates, and geometrical properties of the dust distribution. We apply this tool to the SEDs of simulated mergers and compare the derived results with the reference output from the simulations. Our results indicate that changes in the SEDs of mergers as they approach coalescence and depart from the MS are related to an evolution of dust geometry in scales larger than a few hundred parsecs. This is reflected in a correlation between the specific star formation rate (sSFR), and the compactness parameter C\mathcal{C}, that parametrizes this geometry and hence the evolution of dust temperature (TdustT_{\rm{dust}}) with time. As mergers approach coalescence, they depart from the MS and increase their compactness, which implies that moderate outliers of the MS are consistent with late-type mergers. By further applying our method to real observations of Luminous Infrared Galaxies (LIRGs), we show that the merger scenario is unable to explain these extreme outliers of the MS. Only by significantly increasing the gas fraction in the simulations are we able to reproduce the SEDs of LIRGs.Comment: 18 pages, 10 figures, accepted in Ap

    Permeation of the three aromatic dipeptides through lipid bilayers: Experimental and computational study

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    Publisher's note added August 2016: "This article was originally published online on 27 June 2016 with a sentence missing in the Acknowledgments. After the funding acknowledgments, it should read, “G.S.J. would like to thank Wilson R. Veras Tavarez and Elizabeth De Leon Olmeda of UCC for helpful comments.” AIP Publishing apologizes for this error. All online versions of the article were corrected on 28 June 2016; the article is correct as it appears in the printed version of the journal."The time-resolved parallel artificial membrane permeability assay with fluorescence detection and comprehensive computer simulations are used to study the passive permeation of three aromatic dipeptides—N-acetyl-phenylalanineamide (NAFA), N-acetyltyrosineamide (NAYA), and N-acetyltryptophanamide (NATA) through a 1,2-dioleoyl-sn-glycero-3-phospocholine (DOPC) lipid bilayer. Measured permeation times and permeability coefficients show fastest translocation for NAFA, slowest for NAYA, and intermediate for NATA under physiological temperature and pH. Computationally, we perform umbrella sampling simulations to model the structure, dynamics, and interactions of the peptides as a function of z, the distance from lipid bilayer. The calculated profiles of the potential of mean force show two strong effects—preferential binding of each of the three peptides to the lipid interface and large free energy barriers in the membrane center. We use several approaches to calculate the position-dependent translational diffusion coefficients D(z), including one based on numerical solution the Smoluchowski equation. Surprisingly, computed D(z) values change very little with reaction coordinate and are also quite similar for the three peptides studied. In contrast, calculated values of sidechain rotational correlation times τrot(z) show extremely large changes with peptide membrane insertion—values become 100 times larger in the headgroup region and 10 times larger at interface and in membrane center, relative to solution. The peptides’ conformational freedom becomes systematically more restricted as they enter the membrane, sampling α and ÎČ and C7eq basins in solution, α and C7eq at the interface, and C7eq only in the center. Residual waters of solvation remain around the peptides even in the membrane center. Overall, our study provides an improved microscopic understanding of passive peptide permeation through membranes, especially on the sensitivity of rotational diffusion to position relative to the bilayer. Published by AIP Publishing. [http://dx.doi.org/10.1063/1.4954241

    Evaluation of Steel Bridges, Volumes I & II

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    This report is divided into two volumes. Volume I summarizes a structural health monitoring (SHM) system that was developed for the Iowa DOT to remotely and continuously monitor fatigue critical bridges (FCB) to aid in the detection of crack formation. The developed FCB SHM system enables bridge owners to remotely monitor FCB for gradual or sudden damage formation. The SHM system utilizes fiber bragg grating (FBG) fiber optic sensors (FOSs) to measure strains at critical locations. The strain-based SHM system is trained with measured performance data to identify typical bridge response when subjected to ambient traffic loads, and that knowledge is used to evaluate newly collected data. At specified intervals, the SHM system autonomously generates evaluation reports that summarize the current behavior of the bridge. The evaluation reports are collected and distributed to the bridge owner for interpretation and decision making. This volume (Volume II) summarizes the development and demonstration of an autonomous, continuous SHM system that can be used to monitor typical girder bridges. The developed SHM system can be grouped into two main categories: an office component and a field component. The office component is a structural analysis software program that can be used to generate thresholds which are used for identifying isolated events. The field component includes hardware and field monitoring software which performs data processing and evaluation. The hardware system consists of sensors, data acquisition equipment, and a communication system backbone. The field monitoring software has been developed such that, once started, it will operate autonomously with minimal user interaction. In general, the SHM system features two key uses. First, the system can be integrated into an active bridge management system that tracks usage and structural changes. Second, the system helps owners to identify damage and deterioration

    Resurrecting immortal‐time bias in the study of readmissions

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    ObjectiveTo compare readmission rates as measured by the Centers for Medicare and Medicaid Services and the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) methods.Data Sources20 percent sample of national Medicare data for patients undergoing cystectomy, colectomy, abdominal aortic aneurysm (AAA) repair, and total knee arthroplasty (TKA) between 2010 and 2014.Study DesignRetrospective cohort study comparing 30‐day readmission rates.Data Collection/Extraction MethodsPatients undergoing cystectomy, colectomy, abdominal aortic aneurysm repair, and total knee arthroplasty between 2010 and 2014 were identified.Principal FindingsCystectomy had the highest and total knee arthroplasty had the lowest readmission rate. The NSQIP measure reported significantly lower rates for all procedures compared to the CMS measure, which reflects an immortal‐time bias.ConclusionsWe found significantly different readmission rates across all surgical procedures when comparing CMS and NSQIP measures. Longer length of stay exacerbated these differences. Uniform outcome measures are needed to eliminate ambiguity and synergize research and policy efforts.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154628/1/hesr13252-sup-0001-Authormatrix.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154628/2/hesr13252.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154628/3/hesr13252_am.pd
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