992 research outputs found
Nuclear wastewater decontamination by 3D-Printed hierarchical zeolite monoliths
3D-printed monoliths of zeolites chabazite and 4A were made, characterized, and shown effective for removing strontium and caesium from water
What is stopping you? The falling employment-to-employment mobility in the UK
What contributed to the decline in employment-to-employment (EE) transition rate in the UK in recent decades? This paper empirically examines potential channels that caused the sluggish EE mobility from 2000-2019. First, I break down the observed fall in EE mobility relative to unemployed-to-employment (UE) transition into changes in relative search intensity and worker’s acceptance rate. I find the vast majority of the persistent decline after 2010 was due to fall in job acceptance. Second, I estimate a dynamic job ladder model using UK survey data to examine the relative importance of changes in employment and job offer distribution in reducing job acceptance. Results reveal that the falling job acceptance in the 2000s was attributed to workers moving up the job ladder; while acceptance remained low in the 2010s as a result of deterioration in offer qualities. Counterfactual exercise shows that if the attractiveness of poaching offers did not deteriorate after 2010, the EE mobility would have returned to levels in early 2000s. Finally, I test the contribution of composition changes to the fall in EE rate by implementing a between-within decomposition using a structural framework, which accounts for both worker heterogeneity and sectoral compositions. Results rule out demographic changes or structural transformation as main drivers of the fall in EE rates
Assessing and Improving the Reliability of Volunteered Land Cover Reference Data
Volunteered geographic data are being used increasingly to support land cover mapping and validation, yet the reliability of the volunteered data still requires further research. This study proposes data-based guidelines to help design the data collection by assessing the reliability of volunteered data collected using the Geo-Wiki tool. We summarized the interpretation difficulties of the volunteers at a global scale, including those areas and land cover types that generate the most confusion. We also examined the factors affecting the reliability of majority opinion and individual classification. The results showed that the highest interpretation inconsistency of the volunteers occurred in the ecoregions of tropical and boreal forests (areas with relatively poor coverage of very high resolution images), the tundra (a unique region that the volunteers are unacquainted with), and savannas (transitional zones). The volunteers are good at identifying forests, snow/ice and croplands, but not grasslands and wetlands. The most confusing pairs of land cover types are also captured in this study and they vary greatly with different biomes. The reliability can be improved by providing more high resolution ancillary data, more interpretation keys in tutorials, and tools that assist in coverage estimation for those areas and land cover types that are most prone to confusion. We found that the reliability of the majority opinion was positively correlated with the percentage of volunteers selecting this choice and negatively related to their self-evaluated uncertainty when very high resolution images were available. Factors influencing the reliability of individual classifications were also compared and the results indicated that the interpretation difficulty of the target sample played a more important role than the knowledge base of the volunteers. The professional background and local knowledge had an influence on the interpretation performance, especially in identifying vegetation land cover types other than croplands. These findings can help in building a better filtering system to improve the reliability of volunteered data used in land cover validation and other applications
Nambu-Goldstone Dark Matter and Cosmic Ray Electron and Positron Excess
We propose a model of dark matter identified with a pseudo-Nambu-Goldstone
boson in the dynamical supersymmetry breaking sector in a gauge mediation
scenario. The dark matter particles annihilate via a below-threshold narrow
resonance into a pair of R-axions each of which subsequently decays into a pair
of light leptons. The Breit-Wigner enhancement explains the excess electron and
positron fluxes reported in the recent cosmic ray experiments PAMELA, ATIC and
PPB-BETS without postulating an overdensity in halo, and the limit on
anti-proton flux from PAMELA is naturally evaded.Comment: 3 figure
Ultra-High Energy Neutrino Fluxes: New Constraints and Implications
We apply new upper limits on neutrino fluxes and the diffuse extragalactic
component of the GeV gamma-ray flux to various scenarios for ultra high energy
cosmic rays and neutrinos. As a result we find that extra-galactic top-down
sources can not contribute significantly to the observed flux of highest energy
cosmic rays. The Z-burst mechanism where ultra-high energy neutrinos produce
cosmic rays via interactions with relic neutrinos is practically ruled out if
cosmological limits on neutrino mass and clustering apply.Comment: 10 revtex pages, 9 postscript figure
Epidemiology and management of gout in Taiwan: a nationwide population study
INTRODUCTION: Gout is the most common inflammatory arthritis worldwide and is the only type of chronic arthritis that potentially can be ‘cured’. However, data on gout incidence, prevalence and management, assessed at multiple time points in the same population, are sparse, particularly in Asian populations. The aim of this study was to describe trends in the epidemiology of gout in the general population of Taiwan.
METHODS: The National Health Insurance Research Database was used to identify patients with gout and to estimate the prevalence and incidence of gout for each calendar year from 2005 to 2010. The pattern of gout management was also examined.
RESULTS: Of 23,371,362 beneficiaries in 2010, there were 1,458,569 prevalent and 56,595 incident cases of gout, giving a prevalence of 6.24% (95% confidence interval (CI), 6.23% to 6.25%) and an incidence of 2.74 (95% CI, 2.72 to 2.76) per 1,000 person-years. The annual percentage change (APC) of the standardised prevalence was −0.7% (95% CI, −1.7% to 0.3%; P = 0.14), suggesting that the prevalence of gout was essentially the same throughout the study period. However, The APC of incidence was −13.4 (95% CI, −16.1 to −10.6) between 2005 and 2007 and −2.1 (95% CI, −10.4 to 7.1) between 2007 and 2010. Regions with the highest prevalence and incidence were eastern coastal counties and offshore islets, where indigenous people are clustered. Among prevalent gout cases in 2010, only 22.93% (95% CI, 22.87% to 23.00%) were prescribed urate-lowering treatment (ULT), which remained unchanged between 2005 and 2010 at an APC of 0.0 (95% CI, −3.8 to 4.0). Uricosuric agents were more commonly prescribed than xanthine oxidase inhibitors in Taiwan.
CONCLUSIONS: In Taiwan, 1 in 16 people have gout. Whereas the incidence has decreased recently, the prevalence remains unchanged. Management of gout in Taiwan is poor, with only one in five affected people being treated with ULT
A Qualitative Study on the User Acceptance of a Home-Based Stroke Telerehabilitation System
Objective: This paper reports a qualitative study of a home-based stroke telerehabilitation system. The telerehabilitation system delivers treatment sessions in the form of daily guided rehabilitation games, exercises, and stroke education in the patient’s home. The aims of the current report are to investigate patient perceived benefits of and barriers to using the telerehabilitation system at home.
Methods: We used a qualitative study design that involved in-depth semi-structured interviews with 13 participants who were patients in the subacute phase after stroke and had completed a six-week intervention using the home-based telerehabilitation system. Thematic analysis was conducted to analyze the data.
Results: Participants mostly reported positive experiences with the telerehabilitation system. Benefits included observed improvements in limb functions, cognitive abilities, and emotional well-being. They also perceived the system easy to use due to the engaging experience and the convenience of conducting sessions at home. Meanwhile, participants pointed out the importance of considering technical support and physical environment at home. Further, family members’ support helped them sustain in their rehabilitation. Finally, adjusting difficulty levels and visualizing patients’ rehabilitation progress might help them in continued use of the telerehabilitation system.
Conclusion: Telerehabilitation systems can be used as an efficient and user-friendly tool to deliver home-based stroke rehabilitation that enhance patients’ physical recovery and mental and social-emotional wellbeing. Such systems need to be designed to offer engaging experience, display of recovery progress, and flexibility of schedule and location, with consideration of facilitating and social factors
Light Emission and Conductance Fluctuations in Electrically Driven and Plasmonically Enhanced Molecular Junctions
Electrically connected and plasmonically enhanced molecular junctions combine
the optical functionalities of high field confinement and enhancement (cavity
function), and of high radiative efficiency (antenna function) with the
electrical functionalities of molecular transport and electrically driven light
emission. They are supposed to play a leading role in emerging nanoscale
optoelectronic devices; yet, this development is hindered by an insufficient
control and understanding of atomic-scale phenomena that govern the optical and
electrical behavior of plasmonic nanojunctions under ambient operating
conditions. For instance, displacement of a single atom may drastically
influence the junction's conductance and its optical near-field distribution.
Here, we investigate tunneling-induced light emission from a self-assembled
metal-molecule-metal junction embedded in a plasmonic cavity at
room-temperature. We find that despite the presence of hundreds of molecules in
the junction, electrical conductance and light emission are both highly
sensitive to atomic-scale fluctuations - a phenomenology reminiscent of
picocavities observed in Raman scattering and of luminescence blinking from
photo-excited plasmonic junctions. We present a minimal electrical model that
is able to capture all main experimental features. Contrasting with these
microscopic fluctuations, the overall plasmonic and electronic functionalities
of our devices feature an excellent long-term stability and reproducibility at
room temperature and under electrical bias of several volts, allowing for
measurements over several months. Our work contributes to the understanding of
atomic fluctuations in molecular plasmonic junctions and to the development of
more robust and scalable platforms for nanoscale optoelectronics
Intrinsic thermal vibrations of suspended doubly clamped single-wall carbon nanotubes
We report the observation of thermally driven mechanical vibrations of
suspended doubly clamped carbon nanotubes, grown by chemical vapor deposition
(CVD). Several experimental procedures are used to suspend carbon nanotubes.
The vibration is observed as a blurring in images taken with a scanning
electron microscope. The measured vibration amplitudes are compared with a
model based on linear continuum mechanics.Comment: pdf including figures, see:
http://www.unibas.ch/phys-meso/Research/Papers/2003/NT-Thermal-Vibrations.pd
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