240 research outputs found
Stiffness of Contacts Between Rough Surfaces
The effect of self-affine roughness on solid contact is examined with
molecular dynamics and continuum calculations. The contact area and normal and
lateral stiffnesses rise linearly with the applied load, and the load rises
exponentially with decreasing separation between surfaces. Results for a wide
range of roughnesses, system sizes and Poisson ratios can be collapsed using
Persson's contact theory for continuous elastic media. The atomic scale
response at the interface between solids has little affect on the area or
normal stiffness, but can greatly reduce the lateral stiffness. The scaling of
this effect with system size and roughness is discussed.Comment: 4 pages, 3 figure
Coronavirus Disease (COVID-19):Characteristics in children and considerations for Dentists providing their care
The emergence of the novel virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease (COVID-19) has led to a global pandemic and one of the most significant challenges to the healthcare profession. Dental practices are focal points for cross-infection, and care must be taken to minimise the risk of infection to, from, or between dental care professionals and patients. The COVID-19 epidemiological and clinical characteristics are still being collated but children's symptoms seem to be milder than those that adults experience. It is unknown whether certain groups, for example children with comorbidities, might be at a higher risk of more severe illness. Emerging data on disease spread in children, affected by COVID-19, have not been presented in detail. The purpose of this article was to report current data on the paediatric population affected with COVID-19 and highlight considerations for dentists providing care for children during this pandemic. All members of the dental team have a professional responsibility to keep themselves informed of current guidance and be vigilant in updating themselves as recommendations are changing so quickly.</p
Thermal photons in QGP and non-ideal effects
We investigate the thermal photon production-rates using one dimensional
boost-invariant second order relativistic hydrodynamics to find proper time
evolution of the energy density and the temperature. The effect of
bulk-viscosity and non-ideal equation of state are taken into account in a
manner consistent with recent lattice QCD estimates. It is shown that the
\textit{non-ideal} gas equation of state i.e behaviour
of the expanding plasma, which is important near the phase-transition point,
can significantly slow down the hydrodynamic expansion and thereby increase the
photon production-rates. Inclusion of the bulk viscosity may also have similar
effect on the hydrodynamic evolution. However the effect of bulk viscosity is
shown to be significantly lower than the \textit{non-ideal} gas equation of
state. We also analyze the interesting phenomenon of bulk viscosity induced
cavitation making the hydrodynamical description invalid. We include the
viscous corrections to the distribution functions while calculating the photon
spectra. It is shown that ignoring the cavitation phenomenon can lead to
erroneous estimation of the photon flux.Comment: 11 pages, 13 figures; accepted for publication in JHE
Enabling hypervisor environment for increasing efficiency and effectiveness of training programmes - a case study at NAARM
The National Academy of Agricultural Research Management (NAARM) was established by the Indian Council of Agricultural Research (ICAR) at Hyderabad, in 1976, to address issues related to agricultural research and education management. The Academy also renders services for building IP portfolios like patents and geographical indications to various stakeholders including farmers and scientists. Keeping in view the increasing national and global need to integrate agriculture with agribusiness for raising rural incomes, and the increased emphasis on the creation, dissemination, application and exchange of knowledge in this vital area, the Academy has recently initiated post graduate education programmes and set up an Agribusiness Knowledge Centre. In the above mentioned scenario, NAARM also conducting many training programmes/courses over the year and there is lot of time and money being invested into purchasing physical machines and software. There is a need of maintaining specific set of software required for each training. The Coordinators of the training programmes has to ensure beforehand that all the machines are working fine and all the software required for that training got installed in all machines and working without any issues. This requirement of preparedness for training programmes has been avoided completely by establishing a private cloud which can provide Infrastructure as a Service (IaaS) at our organization. At the end of programmes may it be a regular or refresher course, coordinators has supposed to be evaluate the participants by tools like quizzes and exams. NAARM is using SynchronEyes Student-Teacher software for evaluation purpose. Many issues were there in this examinations system because of network, virus and power problems. This also has been completely avoided by establishing a hybrid cloud
A Composite Metric for Benchmarking Site Performance in TAVR: Results from the STS/ACC TVT Registry
Background: Transcatheter aortic valve replacement (TAVR) is a transformative therapy for aortic stenosis. Despite rapid improvements in technology and techniques, serious complications remain relatively common and are not well described by single outcome measures. The purpose of this study was to determine if there is site-level variation in TAVR outcomes in the United States using a novel 30-day composite measure.
Methods: We performed a retrospective cohort study using data from the STS/ACC TVT Registry to develop a novel ranked composite performance measure that incorporates mortality and serious complications. The selection and rank order of the complications for the composite was determined by their adjusted association with 1-year outcomes. Sites whose risk-adjusted outcomes were significantly more or less frequent than the national average based on a 95% probability interval were classified as performing worse or better than expected.
Results: The development cohort consisted of 52,561 patients who underwent TAVR between January 1, 2015 and December 31, 2017. Based on the associations with 1-year risk-adjusted mortality and health status, we identified four periprocedural complications to include in the composite risk model in addition to mortality. Ranked empirically according to severity, these included stroke, major, life-threatening or disabling bleeding, stage III acute kidney injury, and moderate or severe peri-valvular regurgitation. Based on these ranked outcomes, we found that there was significant site-level variation in quality of care in TAVR in the United States. Overall, better than expected site performance was observed in 25/301 (8%) of sites; performance as expected was observed in 242/301 sites (80%); and worse than expected performance was observed in 34/301 (11%) of sites. Thirty-day mortality, stroke, major, life-threatening or disabling bleeding, and moderate or severe peri-valvular leak were each substantially more common in sites with worse than expected performance as compared with other sites. There was good aggregate reliability of the model.
Conclusions: There are substantial variations in the quality of TAVR care received in the United States, and 11% of sites were identified as providing care below the average level of performance. Further study is necessary to determine structural, process-related, and technical factors associated with high- and low-performing sites
Flow in heavy-ion collisions - Theory Perspective
I review recent developments in the field of relativistic hydrodynamics and
its application to the bulk dynamics in heavy-ion collisions at the
Relativistic Heavy- Ion Collider (RHIC) and the Large Hadron Collider (LHC). In
particular, I report on progress in going beyond second order relativistic
viscous hydrodynamics for conformal fluids, including temperature dependent
shear viscosity to entropy density ratios, as well as coupling hydrodynamic
calculations to microscopic hadronic rescattering models. I describe
event-by-event hydrodynamic simulations and their ability to compute higher
harmonic flow coefficients. Combined comparisons of all harmonics to recent
experimental data from both RHIC and LHC will potentially allow to determine
the desired details of the initial state and the medium properties of the
quark-gluon plasma produced in heavy-ion collisions.Comment: 8 pages, Invited plenary talk at the 22nd International Conference on
Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2011), May 23-28
2011, Annecy, Franc
Solution combustion derived nanocrystalline Zn2SiO4:Mn phosphors: A spectroscopic view
Properties of the nuclear medium
We review our knowledge on the properties of the nuclear medium that have
been studied, along many years, on the basis of many-body theory, laboratory
experiments and astrophysical observations. First we consider the realm of
phenomenological laboratory data and astrophysical observations, and the hints
they can give on the characteristics that the nuclear medium should possess.
The analysis is based on phenomenological models, that however have a strong
basis on physical intuition and an impressive success. More microscopic models
are also considered, and it is shown that they are able to give invaluable
information on the nuclear medium, in particular on its Equation of State. The
interplay between laboratory experiments and astrophysical observations are
particularly stressed, and it is shown how their complementarity enriches
enormously our insights into the structure of the nuclear medium. We then
introduce the nucleon-nucleon interaction and the microscopic many-body theory
of nuclear matter, with a critical discussion about the different approaches
and their results. The Landau Fermi Liquid theory is introduced and briefly
discussed. As illustrative example, we discuss neutron matter at very low
density, and it is shown how it can be treated within the many-body theory. A
section is dedicated to the pairing problem. The connection with nuclear
structure is then discussed, on the basis of the Energy Density Functional
method. The possibility to link the physics of exotic nuclei and the
astrophysics of neutron stars is particularly stressed. Finally we discuss the
thermal properties of the nuclear medium, in particular the liquid-gas phase
transition and its connection with the phenomenology on heavy ion reactions and
the cooling evolution of neutron stars. The presentation has been taken for
non-specialists and possibly for non-nuclear physicists.Comment: 90 pages, 29 figures, revised versio
Inter-diffusion of Plasmonic Metals and Phase Change Materials
This work investigates the problematic diffusion of metal atoms into phase
change chalcogenides, which can destroy resonances in photonic devices.
Interfaces between Ge2Sb2Te5 and metal layers were studied using X-ray
reflectivity (XRR) and reflectometry of metal-Ge2Sb2Te5 layered stacks. The
diffusion of metal atoms influences the crystallisation temperature and optical
properties of phase change materials. When Au, Ag, Al, W structures are
directly deposited on Ge2Sb2Te5 inter-diffusion occurs. Indeed, Au forms AuTe2
layers at the interface. Diffusion barrier layers, such as Si3N4 or stable
diffusionless plasmonic materials, such as TiN, can prevent the interfacial
damage. This work shows that the interfacial diffusion must be considered when
designing phase change material tuned photonic devices, and that TiN is the
most suitable plasmonic material to interface directly with Ge2Sb2Te5.Comment: 23 pages, 8 figures, articl
- …