1,697 research outputs found

    Off-Line, Multi-Detector Intensity Interferometers II: Implications and Applications

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    Intensity interferometry removes the stringent requirements on mechanical precision and atmospheric corrections that plague all amplitude interferometry techniques at the cost of severely limited sensitivity. A new idea we recently introduced, very high redundancy, alleviates this problem. It enables the relatively simple construction (~1cm mechanical precision) of a ground-based astronomical facility able to transform a two-dimensional field of point-like sources to a three-dimensional distribution of micro-arcsec resolved systems, each imaged in several optical bands. Each system will also have its high resolution residual timing, high quality (inside each band) spectra and light curve, emergent flux, effective temperature, polarization effects and perhaps some thermodynamic properties, all directly measured. All the above attributes can be measured in a single observation run of such a dedicated facility. We conclude that after three decades of abandonment optical intensity interferometry deserves another review, also as a ground-based alternative to the science goals of space interferometers.Comment: The article has been accepted for publication in MNRA

    Giardia: a pathogen or commensal for children in high-prevalence settings?

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    Giardia is a common intestinal parasite worldwide, and infection can be associated with clear and sometimes persistent symptomatology. However, in children in high prevalence settings, it is not associated with or is perhaps even protective against acute diarrhea, and the association with long-term outcomes has been difficult to discern

    Open Data Discourse: Consumer Acceptance of Personal Cloud: Integrating Trust and Risk with the Technology Acceptance Model

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    This paper provides the data used to analyze the conceptual replication of Pavlou (2003) by Moqbel and Bartelt (2015) which studied factors that impacted consumer’s behavioral intentions to make online transactions by integrating trust and perceived risk with the technology acceptance model (TAM). We provide a detailed description of the data so it meets the open data standards. In particular, we explain the structure of the data so that other researchers can easily analyze the same dataset to come to the same results and conclusions. Our dataset consists of 240 observations which includes the following constructs: perceived trust, perceived risk, perceived usefulness, perceived ease of use, satisfaction, and perceived familiarity. Control variables include age, sex, educational level, race/ethnicity, employment status, and work experience. Future studies are encouraged to follow the footsteps of this study in providing open data to support the body of knowledge in the IS field

    Open Materials Discourse: Consumer Acceptance of the Personal Cloud: Integrating Trust and Risk with the Technology Acceptance Model

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    This paper provides the materials used to collect survey data for the conceptual replication of Pavlou (2003) by Moqbel and Bartelt (2015). This replication paper used trust and perceived risk, in addition to the technology acceptance model (TAM) factors of perceived usefulness and perceived ease of use, to determine how consumer’s behavioral intentions affect online transactions (Moqbel & Bartelt, 2015). Two hundred forty participants took part in the 15-minute survey, with the option of choosing either online or paper format. This paper provides additional materials and details on how the survey was conducted. Step-by-step explanations are provided for the design, procedures, consent form, survey instructions, and the survey questions. We hope that this background paper will allow others a better understanding of our replication research and will also enable others to adapt our methodological techniques into their research

    Regulation of amylase expression in Aspergillus nidulans

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    We report the secretion of amylase by A. nidulans R153 and repression of its expression by various carbon sources

    Consumer Acceptance of Personal Cloud: Integrating Trust and Risk with the Technology Acceptance Model

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    This paper conducts a conceptual replication of Pavlou (2003) which studied factors that impacted consumer’s behavioral intentions to make online transactions by integrating trust and perceived risk with the technology acceptance model (TAM). We test the generalizability of the model by replicating the study a decade later using a different online setting—personal cloud computing. Our results that are based on 240 observations, confirm the original study’s research model except perceived ease of use lost its direct predictive power to trust, perceived risk and perceived usefulness. Trust continues to be an important factor in perceived ease of use and perceived usefulness and should be an area of focus in online marketing strategies. Perceived usefulness continued to have a significant relationship for consumer’s intentions to use, but perceived ease of use did not affect consumer’s intention to use. Thus, more online businesses should focus on the usefulness of their service(s). Future studies are encouraged to methodologically replicate this study in different contexts and after another period in time to examine whether results hold. *This article has been revised to correct an error (September 2016)

    Defect Formation and Kinetics of Atomic Terrace Merging

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    Pairs of atomic scale terraces on a single crystal metal surface can be made to merge controllably under suitable conditions to yield steps of double height and width. We study the effect of various physical parameters on the formation of defects in a kinetic model of step doubling. We treat this manifestly non- equilibrium problem by mapping the model onto a 1-D random sequential adsorption problem and solving this analytically. We also do simulations to check the validity of our treatment. We find that our treatment effectively captures the dynamic evolution and the final state of the surface morphology. We show that the number and nature of the defects formed is controlled by a single dimensionless parameter qq. For qq close to one we show that the fraction of defects rises linearly with ϵ≡1−q\epsilon \equiv 1-q as 0.284×ϵ0.284 \times \epsilon. We also show that one can arrive at the final state faster and with fewer defects by changing the parameter with time.Comment: 17 pages, 8 figures. To be submitted to Phys. Rev.

    Anomalous Dimension and Spatial Correlations in a Point-Island Model

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    We examine the island size distribution function and spatial correlation function of a model for island growth in the submonolayer regime in both 1 and 2 dimensions. In our model the islands do not grow in shape, and a fixed number of adatoms are added, nucleate, and are trapped at islands as they diffuse. We study the cases of various critical island sizes ii for nucleation as a function of initial coverage. We found anomalous scaling of the island size distribution for large ii . Using scaling, random walk theory, a version of mean-field theory we obtain a closed form for the spatial correlation function. Our analytic results are verified by Monte Carlo simulations

    Labyrinthine Island Growth during Pd/Ru(0001) Heteroepitaxy

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    Using low energy electron microscopy we observe that Pd deposited on Ru only attaches to small sections of the atomic step edges surrounding Pd islands. This causes a novel epitaxial growth mode in which islands advance in a snakelike motion, giving rise to labyrinthine patterns. Based on density functional theory together with scanning tunneling microscopy and low energy electron microscopy we propose that this growth mode is caused by a surface alloy forming around growing islands. This alloy gradually reduces step attachment rates, resulting in an instability that favors adatom attachment at fast advancing step sections
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