4,279 research outputs found
Ab initio diffusional potential energy surface for CO chemisorption on Pd{110} at high coverage: Coupled translation and rotation
[[abstract]]The ground statepotential energy surface for CO chemisorption across Pd{110} has been calculated using density functional theory with gradient corrections at monolayer coverage. The most stable site corresponds well with the experimental adsorption heat, and it is found that the strength of binding to sites is in the following order: pseudo-short-bridge>atop>long-bridge>hollow. Pathways and transition states for CO surfacediffusion, involving a correlation between translation and orientation, are proposed and discussed.[[notice]]補正完畢[[journaltype]]國外[[booktype]]紙本[[countrycodes]]US
Evaluation of Community-Based Trichiasis Surgery in Northwest Ethiopia
Background: Surgery to correct trachomatous trichiasis (TT) is recommended to prevent blindness caused by trachoma. This study evaluated the outcomes of community-based trichiasis surgery with absorbable sutures, conductd in Amhara Regional State, Ethiopia.Methods: A simple random sample of 431 patients was selected from surgical campaign records of which 363 (84.2%) were traced and enrolled into the study. Participants were interviewed and examined for trichiasis recurrence, complications of TT surgery and corneal opacity. Multilevel logistic regression models were used to explore the associations between trichiasis recurrence, corneal opacity and explanatory variables at the eye level.Results: The prevalence of trichiasis recurrence was 9.4% (95% Confidence Interval [CI] 6.6-12.8) and corneal opacity was found in 14.3% (95% CI 10.9-18.3) of the study participants. The proportion of participants with complications of TT surgery was: granuloma 0.6% (95% CI 0.1-2.0); lid closure defects 5.5% (95% CI 3.4-8.4) and lid notching 16.8% (95% CI 13.1-21.1). No factors were identified for trichiasis recurrence. Corneal opacity was associated with increased age (Ptrend=0.001), more than 12 months post surgery (OR=2.7; 95%CI 1.3-5.6), trichiasis surgery complications (OR=2.9; 95%CI 1.4-5.9) and trichiasis recurrence (OR=2.5; 95%CI 1.0-6.3).Conclusion: Prevalence of recurrent trichiasis and granuloma were lower than expected but higher for lid closure defects and lid notching. The majority of the participants reported satisfaction with the trichiasis surgery they had undergone. The findings suggest that recurrence of trichiasis impacts on the patients’ risk of developing corneal opacity but longitudinal studies are required to confirm this.Keywords: Corneal opacity, Trichiasis, Trichiasis recurrence, Ethiopi
Enabling Big Data Analytics at Manufacturing Fields of Farplas Automotive
Digitization and data-driven manufacturing process is needed for today's
industry. The term Industry 4.0 stands for today industrial digitization which
is defined as a new level of organization and control over the entire value
chain of the life cycle of products; it is geared towards increasingly
individualized customer's high-quality expectations. However, due to the
increase in the number of connected devices and the variety of data, it has
become difficult to store and analyze data with conventional systems. The
motivation of this paper is to provide an overview of the understanding of the
big data pipeline, providing a real-time on-premise data acquisition, data
compression, data storage and processing with Apache Kafka and Apache Spark
implementation on Apache Ha-doop cluster, and identifying the challenges and
issues occurring with implementation the Farplas manufacturing company, which
is one of the biggest Tier 1 automotive supplier in Turkey, to study the new
trends and streams related to topics via Industry 4.0.Comment: 8 page
Comparing approaches for modelling indirect contact transmission of infectious diseases
Mathematical models describing indirect contact transmission are an important component of infectious disease mitigation and risk assessment. A model that tracks microorganisms between compartments by coupled ordinary differential equations or a Markov chain is benchmarked against a mechanistic interpretation of the physical transfer of microorganisms from surfaces to fingers and subsequently to a susceptible person's facial mucosal membranes. The primary objective was to compare these models in their estimates of doses and changes in microorganism concentrations on hands and fomites over time. The abilities of the models to capture the impact of episodic events, such as hand hygiene, and of contact patterns were also explored. For both models, greater doses were estimated for the asymmetrical scenarios in which a more contaminated fomite was touched more often. Differing representations of hand hygiene in the Markov model did not notably impact estimated doses but affected pathogen concentration dynamics on hands. When using the Markov model, losses due to hand hygiene should be handled as separate events as opposed to time-averaging expected losses. The discrete event model demonstrated the effect of hand-to-mouth contact timing on the dose. Understanding how model design influences estimated doses is important for advancing models as reliable risk assessment tools
Nature of magnetism in thiol-capped gold nanoparticles investigated with Muon spin rotation
© 2018 Author(s). Muon spin rotation/relaxation measurements show clear evidence for magnetism in 2.2 nm gold nanoparticles capped with butanethiol. At low temperatures (1.8 K), there is significant spin relaxation which decreases as a function of both the applied longitudinal magnetic field and increasing temperature. The results indicate that there are spatially inhomogeneous electronic moments that fluctuate with a wide distribution of correlation times. Possible explanations are discussed
Evaluating a transfer gradient assumption in a fomite-mediated microbial transmission model using an experimental and Bayesian approach
Current microbial exposure models assume that microbial exchange follows a concentration gradient during hand-to-surface contacts. Our objectives were to evaluate this assumption using transfer efficiency experiments and to evaluate a model's ability to explain concentration changes using approximate Bayesian computation (ABC) on these experimental data. Experiments were conducted with two phages (MS2, ΦX174) simultaneously to study bidirectional transfer. Concentrations on the fingertip and surface were quantified before and after fingertip-to-surface contacts. Prior distributions for surface and fingertip swabbing efficiencies and transfer efficiency were used to estimate concentrations on the fingertip and surface post contact. To inform posterior distributions, Euclidean distances were calculated for predicted detectable concentrations (log10 PFU cm−2) on the fingertip and surface post contact in comparison with experimental values. To demonstrate the usefulness of posterior distributions in calibrated model applications, posterior transfer efficiencies were used to estimate rotavirus infection risks for a fingertip-to-surface and subsequent fingertip-to-mouth contact. Experimental findings supported the transfer gradient assumption. Through ABC, the model explained concentration changes more consistently when concentrations on the fingertip and surface were similar. Future studies evaluating microbial transfer should consider accounting for differing fingertip-to-surface and surface-to-fingertip transfer efficiencies and extend this work for other microbial types
The two-hour orbit of a binary millisecond X-ray pulsar
Typical radio pulsars are magnetized neutron stars that are born rapidly
rotating and slow down as they age on time scales of 10 to 100 million years.
However, millisecond radio pulsars spin very rapidly even though many are
billions of years old. The most compelling explanation is that they have been
"spun up" by the transfer of angular momentum during accretion of material from
a companion star in so-called low-mass X-ray binary systems, LMXBs. (LMXBs
consist of a neutron star or black hole accreting from a companion less than
one solar mass.) The recent detection of coherent X-ray pulsations with a
millisecond period from a suspected LMXB system appears to confirm this link.
Here we report observations showing that the orbital period of this binary
system is two hours, which establishes it as an LMXB. We also find an apparent
modulation of the X-ray flux at the orbital period (at the two per cent level),
with a broad minimum when the pulsar is behind this low-mass companion star.
This system seems closely related to the "black widow" millisecond radio
pulsars, which are evaporating their companions through irradiation. It may
appear as an eclipsing radio pulsar during periods of X-ray quiescence.Comment: 4 pages with 1 figure. Style files included. Fig. 2 deleted and text
revised. To appear in Nature. Press embargo until 18:00 GMT on 1998 July 2
Direct observation of spin-polarised bulk bands in an inversion-symmetric semiconductor
Methods to generate spin-polarised electronic states in non-magnetic solids
are strongly desired to enable all-electrical manipulation of electron spins
for new quantum devices. This is generally accepted to require breaking global
structural inversion symmetry. In contrast, here we present direct evidence
from spin- and angle-resolved photoemission spectroscopy for a strong spin
polarisation of bulk states in the centrosymmetric transition-metal
dichalcogenide WSe. We show how this arises due to a lack of inversion
symmetry in constituent structural units of the bulk crystal where the
electronic states are localised, leading to enormous spin splittings up to
eV, with a spin texture that is strongly modulated in both real and
momentum space. As well as providing the first experimental evidence for a
recently-predicted `hidden' spin polarisation in inversion-symmetric materials,
our study sheds new light on a putative spin-valley coupling in
transition-metal dichalcogenides, of key importance for using these compounds
in proposed valleytronic devices.Comment: 6 pages, 4 figure
A reverse engineering approach to the suppression of citation biases reveals universal properties of citation distributions
The large amount of information contained in bibliographic databases has
recently boosted the use of citations, and other indicators based on citation
numbers, as tools for the quantitative assessment of scientific research.
Citations counts are often interpreted as proxies for the scientific influence
of papers, journals, scholars, and institutions. However, a rigorous and
scientifically grounded methodology for a correct use of citation counts is
still missing. In particular, cross-disciplinary comparisons in terms of raw
citation counts systematically favors scientific disciplines with higher
citation and publication rates. Here we perform an exhaustive study of the
citation patterns of millions of papers, and derive a simple transformation of
citation counts able to suppress the disproportionate citation counts among
scientific domains. We find that the transformation is well described by a
power-law function, and that the parameter values of the transformation are
typical features of each scientific discipline. Universal properties of
citation patterns descend therefore from the fact that citation distributions
for papers in a specific field are all part of the same family of univariate
distributions.Comment: 9 pages, 6 figures. Supporting information files available at
http://filrad.homelinux.or
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