5,220 research outputs found
Comment on "Electron transport through correlated molecules computed using the time-independent Wigner function: Two critical tests"
The many electron correlated scattering (MECS) approach to quantum electronic
transport was investigated in the linear response regime [I. Baldea and H.
Koeppel, Phys. Rev. B. 78, 115315 (2008)]. The authors suggest, based on
numerical calculations, that the manner in which the method imposes boundary
conditions is unable to reproduce the well-known phenomena of conductance
quantization. We introduce an analytical model and demonstrate that conductance
quantization is correctly obtained using open system boundary conditions within
the MECS approach.Comment: 18 pages, 4 figures. Physical Review B, to appea
An investigation of the basic properties of irradiated polyethylene memory materials
Properties of irradiated polyethylene memory material
Formation and Equilibrium Properties of Living Polymer Brushes
Polydisperse brushes obtained by reversible radical chain polymerization
reaction onto a solid substrate with surface-attached initiators, are studied
by means of an off-lattice Monte Carlo algorithm of living polymers (LP).
Various properties of such brushes, like the average chain length and the
conformational orientation of the polymers, or the force exerted by the brush
on the opposite container wall, reveal power-law dependence on the relevant
parameters. The observed molecular weight distribution (MWD) of the grafted LP
decays much more slowly than the corresponding LP bulk system due to the
gradient of the monomer density within the dense pseudo-brush which favors
longer chains. Both MWD and the density profiles of grafted polymers and chain
ends are well fitted by effective power laws whereby the different exponents
turn out to be mutually self-consistent for a pseudo-brush in the
strong-stretching regime.Comment: 33 pages, 11 figues, J.Chem. Phys. accepted Oct. 199
Dynamical Monte Carlo Study of Equilibrium Polymers : Static Properties
We report results of extensive Dynamical Monte Carlo investigations on
self-assembled Equilibrium Polymers (EP) without loops in good solvent. (This
is thought to provide a good model of giant surfactant micelles.) Using a novel
algorithm we are able to describe efficiently both static and dynamic
properties of systems in which the mean chain length \Lav is effectively
comparable to that of laboratory experiments (up to 5000 monomers, even at high
polymer densities). We sample up to scission energies of over
nearly three orders of magnitude in monomer density , and present a
detailed crossover study ranging from swollen EP chains in the dilute regime up
to dense molten systems. Confirming recent theoretical predictions, the
mean-chain length is found to scale as \Lav \propto \phi^\alpha \exp(\delta
E) where the exponents approach
and in the
dilute and semidilute limits respectively. The chain length distribution is
qualitatively well described in the dilute limit by the Schulz-Zimm
distribution \cN(s)\approx s^{\gamma-1} \exp(-s) where the scaling variable
is s=\gamma L/\Lav. The very large size of these simulations allows also an
accurate determination of the self-avoiding walk susceptibility exponent
. ....... Finite-size effects are discussed in
detail.Comment: 15 pages, 14 figures, LATE
Development of Ocular Inserts for Cattle
Ring shaped ocular inserts have been developed to administer a therapeutic level of tylosin tartrate throughout a five day period to treat pinkeye in cattle. The inserts are based on polyvinyl chloride rings which are dip coated with a copolymer containing the antibiotic (tylosin tartrate). Scanning electron microscope (SEM) characterization of surfaces has been of value to evaluate the presence and extent of surface flaws in the hydrogel coating, and to contribute to improvement in fabrication of the rings to insure the establishment of satisfactory seals at joints, uniformity of microporosity and cross sections, and the absence of significant cracking or flaking. In vitro release rates were determined using-thin layer chromatography techniques, and rates were seen to be above a few micrograms of antibiotic per hour for experiments as long as nine days at simulated tear rates as high as 2 milliliters per hour
Comment on āElectron transport through correlated molecules computed using the time-independent Wigner function: Two critical testsā
The respiratory pathology in infants with sudden unexpected deaths in whom respiratory specimens were initially PCR-positive or PCR-negative for Bordetella pertussis
Background: In a previous controlled study, we investigated the relationship between Bordetella pertussis infections and sudden unexpected deaths among German infants (sudden infant death syndrome, SIDS). In this present study, we investigated further the respiratory pathology in a subset of infants in the original study. Methods: Originally, there were 234 infants with SIDS and, of these, 12 had either a nasopharyngeal swab (NPS) or a tracheal swab specimen (TS) that was positive for B. pertussis by polymerase chain reaction (PCR). Here, tissue specimens from eight infants who were originally PCR-positive were compared with tissue specimens from seven infants in whom the original PCR studies were negative. Results: The histopathologic diagnoses were as follows: 14 of 15 had pulmonary edema and the remaining case had early diffuse alveolar damage. Although 14 of 15 cases had some histologic or clinical evidence suggesting respiratory tract infection, the features were more consistent with a viral etiology, and in none were the findings typical of respiratory disease attributable to B. pertussis. Conclusions: The findings in this present investigation do not support a direct role of B. pertussis at the site of infection (ciliated epithelium) in the causation of SIDS. The clinical aspects of this study were carried out in the 1990s when pertussis was widespread in Germany. Therefore, the original finding of some PCR-positive cases is not surprising. The possibility that B. pertussis infection could still be a factor in some SIDS cases, e.g., by a systemic release of toxins, cannot be definitely ruled ou
Rates and Predictors of Professional Interpreting Provision for Patients With Limited English Proficiency in the Emergency Department and Inpatient Ward.
The provision of professional interpreting services in the hospital setting decreases communication errors of clinical significance and improves clinical outcomes. A retrospective audit was conducted at a tertiary referral adult hospital in Brisbane, Australia. Of 20ā563 admissions of patients presenting to the hospital emergency department (ED) and admitted to a ward during 2013-2014, 582 (2.8%) were identified as requiring interpreting services. In all, 19.8% of admissions were provided professional interpreting services in the ED, and 26.1% were provided on the ward. Patients were more likely to receive interpreting services in the ED if they were younger, spoke an Asian language, or used sign language. On the wards, using sign language was associated with 3 times odds of being provided an interpreter compared with other languages spoken. Characteristics of patients including their age and type of language spoken influence the clinician's decision to engage a professional interpreter in both the ED and inpatient ward
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