4,176 research outputs found
Relationship between Thermodynamic Driving Force and One-Way Fluxes in Reversible Chemical Reactions
Chemical reaction systems operating in nonequilibrium open-system states
arise in a great number of contexts, including the study of living organisms,
in which chemical reactions, in general, are far from equilibrium. Here we
introduce a theorem that relates forward and re-verse fluxes and free energy
for any chemical process operating in a steady state. This rela-tionship, which
is a generalization of equilibrium conditions to the case of a chemical process
occurring in a nonequilibrium steady state, provides a novel equivalent
definition for chemical reaction free energy. In addition, it is shown that
previously unrelated theories introduced by Ussing and Hodgkin and Huxley for
transport of ions across membranes, Hill for catalytic cycle fluxes, and Crooks
for entropy production in microscopically reversible systems, are united in a
common framework based on this relationship.Comment: 11 page
Assessment of accuracy and recognition of three-dimensional computerized forensic craniofacial reconstruction
Facial reconstruction is a technique that aims to reproduce the individual facial characteristics based on interpretation of the skull, with the objective of recognition leading to identification. The aim of this paper was to evaluate the accuracy and recognition level of three-dimensional (3D) computerized forensic craniofacial reconstruction (CCFR) performed in a blind test on open-source software using computed tomography (CT) data from live subjects. Four CCFRs were produced by one of the researchers, who was provided with information concerning the age, sex, and ethnic group of each subject. The CCFRs were produced using Blender® with 3D models obtained from the CT data and templates from the MakeHuman® program. The evaluation of accuracy was carried out in CloudCompare, by geometric comparison of the CCFR to the subject 3D face model (obtained from the CT data). A recognition level was performed using the Picasa® recognition tool with a frontal standardized photography, images of the subject CT face model and the CCFR. Soft-tissue depth and nose, ears and mouth were based on published data, observing Brazilian facial parameters. The results were presented from all the points that form the CCFR model, with an average for each comparison between 63% and 74% with a distance -2.5 ≤ x ≤ 2.5 mm from the skin surface. The average distances were 1.66 to 0.33 mm and greater distances were observed around the eyes, cheeks, mental and zygomatic regions. Two of the four CCFRs were correctly matched by the Picasa® tool. Free software programs are capable of producing 3D CCFRs with plausible levels of accuracy and recognition and therefore indicate their value for use in forensic applications
Could Public Restrooms Be an Environment for Bacterial Resistomes?
PMCID: PMC3547874This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
A Special Homotopy Continuation Method For A Class of Polynomial Systems
A special homotopy continuation method, as a combination of the polyhedral
homotopy and the linear product homotopy, is proposed for computing all the
isolated solutions to a special class of polynomial systems. The root number
bound of this method is between the total degree bound and the mixed volume
bound and can be easily computed. The new algorithm has been implemented as a
program called LPH using C++. Our experiments show its efficiency compared to
the polyhedral or other homotopies on such systems. As an application, the
algorithm can be used to find witness points on each connected component of a
real variety
Non-Perturbative Renormalization Group for Simple Fluids
We present a new non perturbative renormalization group for classical simple
fluids. The theory is built in the Grand Canonical ensemble and in the
framework of two equivalent scalar field theories as well. The exact mapping
between the three renormalization flows is established rigorously. In the Grand
Canonical ensemble the theory may be seen as an extension of the Hierarchical
Reference Theory (L. Reatto and A. Parola, \textit{Adv. Phys.}, \textbf{44},
211 (1995)) but however does not suffer from its shortcomings at subcritical
temperatures. In the framework of a new canonical field theory of liquid state
developed in that aim our construction identifies with the effective average
action approach developed recently (J. Berges, N. Tetradis, and C. Wetterich,
\textit{Phys. Rep.}, \textbf{363} (2002))
Comments on Holographic Entanglement Entropy and RG Flows
Using holographic entanglement entropy for strip geometry, we construct a
candidate for a c-function in arbitrary dimensions. For holographic theories
dual to Einstein gravity, this c-function is shown to decrease monotonically
along RG flows. A sufficient condition required for this monotonic flow is that
the stress tensor of the matter fields driving the holographic RG flow must
satisfy the null energy condition over the holographic surface used to
calculate the entanglement entropy. In the case where the bulk theory is
described by Gauss-Bonnet gravity, the latter condition alone is not sufficient
to establish the monotonic flow of the c-function. We also observe that for
certain holographic RG flows, the entanglement entropy undergoes a 'phase
transition' as the size of the system grows and as a result, evolution of the
c-function may exhibit a discontinuous drop.Comment: References adde
Measuring the effect of enhanced cleaning in a UK hospital : a prospective cross-over study
Increasing hospital-acquired infections have generated much attention over the last decade. There is evidence that hygienic cleaning has a role in the control of hospital-acquired infections. This study aimed to evaluate the potential impact of one additional cleaner by using microbiological standards based on aerobic colony counts and the presence of Staphylococcus aureus including meticillin-resistant S. aureus. We introduced an additional cleaner into two matched wards from Monday to Friday, with each ward receiving enhanced cleaning for six months in a cross-over design. Ten hand-touch sites on both wards were screened weekly using standardised methods and patients were monitored for meticillin-resistant S. aureus infection throughout the year-long study. Patient and environmental meticillin-resistant S. aureus isolates were characterised using molecular methods in order to investigate temporal and clonal relationships. Enhanced cleaning was associated with a 32.5% reduction in levels of microbial contamination at handtouch sites when wards received enhanced cleaning (P < 0.0001: 95% CI 20.2%, 42.9%). Near-patient sites (lockers, overbed tables and beds) were more frequently contaminated with meticillin-resistant S. aureus/S. aureus than sites further from the patient (P = 0.065). Genotyping identified indistinguishable strains from both handtouch sites and patients. There was a 26.6% reduction in new meticillin-resistant S. aureus infections on the wards receiving extra cleaning, despite higher meticillin-resistant S. aureus patient-days and bed occupancy rates during enhanced cleaning periods (P = 0.032: 95% CI 7.7%, 92.3%). Adjusting for meticillin-resistant S. aureus patient-days and based upon nine new meticillin-resistant S. aureus infections seen during routine cleaning, we expected 13 new infections during enhanced cleaning periods rather than the four that actually occurred. Clusters of new meticillin-resistant S. aureus infections were identified 2 to 4 weeks after the cleaner left both wards. Enhanced cleaning saved the hospital £30,000 to £70,000.Introducing one extra cleaner produced a measurable effect on the clinical environment, with apparent benefit to patients regarding meticillin-resistant S. aureus infection. Molecular epidemiological methods supported the possibility that patients acquired meticillin-resistant S. aureus from environmental sources. These findings suggest that additional research is warranted to further clarify the environmental, clinical and economic impact of enhanced hygienic cleaning as a component in the control of hospital-acquired infection
Search For Heavy Pointlike Dirac Monopoles
We have searched for central production of a pair of photons with high
transverse energies in collisions at TeV using of data collected with the D\O detector at the Fermilab Tevatron in
1994--1996. If they exist, virtual heavy pointlike Dirac monopoles could
rescatter pairs of nearly real photons into this final state via a box diagram.
We observe no excess of events above background, and set lower 95% C.L. limits
of on the mass of a spin 0, 1/2, or 1 Dirac
monopole.Comment: 12 pages, 4 figure
Impact Factor: outdated artefact or stepping-stone to journal certification?
A review of Garfield's journal impact factor and its specific implementation
as the Thomson Reuters Impact Factor reveals several weaknesses in this
commonly-used indicator of journal standing. Key limitations include the
mismatch between citing and cited documents, the deceptive display of three
decimals that belies the real precision, and the absence of confidence
intervals. These are minor issues that are easily amended and should be
corrected, but more substantive improvements are needed. There are indications
that the scientific community seeks and needs better certification of journal
procedures to improve the quality of published science. Comprehensive
certification of editorial and review procedures could help ensure adequate
procedures to detect duplicate and fraudulent submissions.Comment: 25 pages, 12 figures, 6 table
Search for High Mass Photon Pairs in p-pbar --> gamma-gamma-jet-jet Events at sqrt(s)=1.8 TeV
A search has been carried out for events in the channel p-barp --> gamma
gamma jet jet. Such a signature can characterize the production of a
non-standard Higgs boson together with a W or Z boson. We refer to this
non-standard Higgs, having standard model couplings to vector bosons but no
coupling to fermions, as a "bosonic Higgs." With the requirement of two high
transverse energy photons and two jets, the diphoton mass (m(gamma gamma))
distribution is consistent with expected background. A 90(95)% C.L. upper limit
on the cross section as a function of mass is calculated, ranging from
0.60(0.80) pb for m(gamma gamma) = 65 GeV/c^2 to 0.26(0.34) pb for m(gamma
gamma) = 150 GeV/c^2, corresponding to a 95% C.L. lower limit on the mass of a
bosonic Higgs of 78.5 GeV/c^2.Comment: 9 pages, 3 figures. Replacement has new H->gamma gamma branching
ratios and corresponding new mass limit
- …
