Impurity in a Luttinger liquid away from half-filling: a numerical study

Conformal field theory gives quite detailed predictions for the low energy spectrum and scaling exponents of a massless Luttinger liquid at generic filling in the presence of an impurity. While these predictions were verified for half-filled systems, there was till now no analysis away from this particular filling. Here, we fill in this gap by numerically investigating a quarter-filled system using the density matrix renormalization group technique. Our results confirm conformal field theory predictions, and suggest that they are indeed valid for arbitrary fillings.Comment: 9 pages (include figures), one reference added in this new versio

Pairing in Cu-O Models: Clues of Joint Electron-Phonon and Electron-Electron Interactions

We discuss a many-electron Hamiltonian with Hubbard-like repulsive interaction and linear coupling to the phonon branches, having the Cu-O plane of the superconducting cuprates as a paradigm. A canonical transformation extracts an effective two-body problem from the many-body theory. As a prototype system we study the \cu cluster, which yields electronic pairing in the Hubbard model; moreover, a standard treatment of the Jahn-Teller effect predicts distortions that destroy electronic pairing. Remarkably, calculations that keep all the electronic spectrum into account show that vibrations are likely to be synergic with electronic pairing, if the coupling to half-breathing modes predominates, as experiments suggest.Comment: 4 pages, 3 figures, accepted by Phys. Rev.

DNA cruciform arms nucleate through a correlated but non-synchronous cooperative mechanism

Inverted repeat (IR) sequences in DNA can form non-canonical cruciform structures to relieve torsional stress. We use Monte Carlo simulations of a recently developed coarse-grained model of DNA to demonstrate that the nucleation of a cruciform can proceed through a cooperative mechanism. Firstly, a twist-induced denaturation bubble must diffuse so that its midpoint is near the centre of symmetry of the IR sequence. Secondly, bubble fluctuations must be large enough to allow one of the arms to form a small number of hairpin bonds. Once the first arm is partially formed, the second arm can rapidly grow to a similar size. Because bubbles can twist back on themselves, they need considerably fewer bases to resolve torsional stress than the final cruciform state does. The initially stabilised cruciform therefore continues to grow, which typically proceeds synchronously, reminiscent of the S-type mechanism of cruciform formation. By using umbrella sampling techniques we calculate, for different temperatures and superhelical densities, the free energy as a function of the number of bonds in each cruciform along the correlated but non-synchronous nucleation pathways we observed in direct simulations.Comment: 12 pages main paper + 11 pages supplementary dat

Using the Engaging Parents in Education for Discharge (\u3cem\u3ee\u3c/em\u3ePED) iPad Application to Improve Parent Discharge Experience

Purpose The purpose of this study was to evaluate the use of the Engaging Parents in Education for Discharge (ePED) iPad application on parent experiences of hospital discharge teaching and care coordination. Hypotheses were: parents exposed to discharge teaching using ePED will have 1) higher quality of discharge teaching and 2) better care coordination than parents exposed to usual discharge teaching. The secondary purpose examined group differences in the discharge teaching, care coordination, and 30-day readmissions for parents of children with and without a chronic condition. Design/Methods Using a quasi-experimental design, ePED was implemented on one inpatient unit (n = 211) and comparison group (n = 184) from a separate unit at a pediatric academic medical center. Patient experience outcome measures collected on day of discharge included Quality of Discharge Teaching Scale-Delivery (QDTS-D) and care coordination measured by Care Transition Measure (CTM). Thirty-day readmission was abstracted from records. Results Parents taught using ePED reported higher QDTS-D scores than parents without ePED (p = .002). No differences in CTM were found between groups. Correlations between QDTS-D and CTM were small for ePED (r = 0.14, p 0.03) and non-ePED (r = 0.29, p \u3c .001) parent groups. CTM was weakly associated with 30-day readmissions in the ePED group. Conclusion The use of ePED by the discharging nurse enhances parent-reported quality of discharge teaching. Practice implications The ePED app is a theory-based structured conversation guide to engage parents in discharge preparation. Nursing implementation of ePED contributes to optimizing the patient/family healthcare experience

Engaging Parents in Education for Discharge (\u3cem\u3ee\u3c/em\u3ePED): Evaluating the Reach, Adoption & Implementation of an Innovative Discharge Teaching Method

Purpose This paper describes the evaluation of the implementation of an innovative teaching method, the “Engaging Parents in Education for Discharge” (ePED) iPad application (app), at a pediatric hospital. Design and methods The Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework was used to guide the evaluation. Three of the five RE-AIM elements are addressed in this study: Reach, Adoption, and Implementation. Results The Reach of the ePED was 245 of 1015 (24.2%) patient discharges. The Adoption rate was 211 of 245 (86%) patients discharged in the five months\u27 study period. High levels of fidelity (89.3%) to Implementation of the ePED were attained: the Signs and Symptoms domain had the highest (93%) and Thinking Forward about Family Adjustment screen had the lowest fidelity (83.3%). Nurse themes explained implementation fidelity: “It takes longer”, and “Forgot to do it.” Conclusions The ePED app operationalized how to have an engaging structured discharge conversation with parents. While the Reach of the ePED app was low under the study conditions, the adoption rate was positive. Nurses were able to integrate a theory-driven practice change into their daily routine when using the ePED app. Implications for practice The rates of adoption and implementation fidelity support the feasibility of future hospital wide implementation to improve patient and family healthcare experience. Attention to training of new content and the interactive conversation approach will be needed to fully leverage the value of the ePED app. Future studies are needed to evaluate the maintenance of the ePED app

Changes in the Treatment Responses to Artesunate-Mefloquine on the Northwestern Border of Thailand during 13 Years of Continuous Deployment

Background: Artemisinin combination treatments (ACT) are recommended as first line treatment for falciparum malaria throughout the malaria affected world. We reviewed the efficacy of a 3-day regimen of mefloquine and artesunate regimen (MAS ), over a 13 year period of continuous deployment as first-line treatment in camps for displaced persons and in clinics for migrant population along the Thai-Myanmar border. Methods and Findings: 3,264 patients were enrolled in prospective treatment trials between 1995 and 2007 and treated with MAS. The proportion of patients with parasitaemia persisting on day-2 increased significantly from 4.5% before 2001 to 21.9% since 2002 (p<0.001). Delayed parasite clearance was associated with increased risk of developing gametocytaemia (AOR = 2.29; 95% CI, 2.00-2.69, p = 0.002). Gametocytaemia on admission and carriage also increased over the years (p = 0.001, test for trend, for both). MAS efficacy has declined slightly but significantly (Hazards ratio 1.13; 95% CI, 1.07-1.19, p<0.001), although efficacy in 2007 remained well within acceptable limits: 96.5% (95% CI, 91.0-98.7). The in vitro susceptibility of P. falciparum to artesunate increased significantly until 2002, but thereafter declined to levels close to those of 13 years ago (geometric mean in 2007: 4.2 nM/l; 95% CI, 3.2-5.5). The proportion of infections caused by parasites with increased pfmdr1 copy number rose from 30% (12/ 40) in 1996 to 53% (24/45) in 2006 (p = 0.012, test for trend). Conclusion: Artesunate-mefloquine remains a highly efficacious antimalarial treatment in this area despite 13 years of widespread intense deployment, but there is evidence of a modest increase in resistance. Of particular concern is the slowing of parasitological response to artesunate and the associated increase in gametocyte carriage. © 2009 Carrara et al

Environmental Exposures and Invasive Meningococcal Disease: An Evaluation of Effects on Varying Time Scales

Invasive meningococcal disease (IMD) is an important cause of meningitis and bacteremia worldwide. Seasonal variation in IMD incidence has long been recognized, but mechanisms responsible for this phenomenon remain poorly understood. The authors sought to evaluate the effect of environmental factors on IMD risk in Philadelphia, Pennsylvania, a major urban center. Associations between monthly weather patterns and IMD incidence were evaluated using multivariable Poisson regression models controlling for seasonal oscillation. Short-term weather effects were identified using a case-crossover approach. Both study designs control for seasonal factors that might otherwise confound the relation between environment and IMD. Incidence displayed significant wintertime seasonality (for oscillation, P < 0.001), and Poisson regression identified elevated monthly risk with increasing relative humidity (per 1% increase, incidence rate ratio = 1.04, 95% confidence interval: 1.004, 1.08). Case-crossover methods identified an inverse relation between ultraviolet B radiation index 1–4 days prior to onset and disease risk (odds ratio = 0.54, 95% confidence interval: 0.34, 0.85). Extended periods of high humidity and acute changes in ambient ultraviolet B radiation predict IMD occurrence in Philadelphia. The latter effect may be due to decreased pathogen survival or virulence and may explain the wintertime seasonality of IMD in temperate regions of North America

The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey

We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results clearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the {\Lambda}CDM cosmological model. At l > 3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8{\sigma} level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.Comment: 19 pages, 13 figures. Submitted to ApJ. This paper is a companion to Hajian et al. (2010) and Dunkley et al. (2010