Approximation of excitonic absorption in disordered systems using a compositional component weighted CPA

Employing a recently developed technique of component weighted two particle Green's functions in the CPA of a binary substitutional alloy $A_cB_{1-c}$ we extend the existing theory of excitons in such media using a contact potential model for the interaction between electrons and holes to an approximation which interpolates correctly between the limits of weak and strong disorder. With our approach we are also able to treat the case where the contact interaction between carriers varies between sites of different types, thus introducing further disorder into the system. Based on this approach we study numerically how the formation of exciton bound states changes as the strengths of the contact potentials associated with either of the two site types are varied through a large range of parameter values.Comment: 27 pages RevTeX (preprint format), 13 Postscript figure file

Faster linearizability checking via PP-compositionality

Linearizability is a well-established consistency and correctness criterion for concurrent data types. An important feature of linearizability is Herlihy and Wing's locality principle, which says that a concurrent system is linearizable if and only if all of its constituent parts (so-called objects) are linearizable. This paper presents $P$-compositionality, which generalizes the idea behind the locality principle to operations on the same concurrent data type. We implement $P$-compositionality in a novel linearizability checker. Our experiments with over nine implementations of concurrent sets, including Intel's TBB library, show that our linearizability checker is one order of magnitude faster and/or more space efficient than the state-of-the-art algorithm.Comment: 15 pages, 2 figure

Conservation laws of semidiscrete canonical Hamiltonian equations

There are many evolution partial differential equations which can be cast into Hamiltonian form. Conservation laws of these equations are related to one-parameter Hamiltonian symmetries admitted by the PDEs. The same result holds for semidiscrete Hamiltonian equations. In this paper we consider semidiscrete canonical Hamiltonian equations. Using symmetries, we find conservation laws for the semidiscretized nonlinear wave equation and Schrodinger equation.Comment: 19 pages, 2 table

How are "teaching the teachers" courses in evidence based medicine evaluated? A systematic review

Background Teaching of evidence-based medicine (EBM) has become widespread in medical education. Teaching the teachers (TTT) courses address the increased teaching demand and the need to improve effectiveness of EBM teaching. We conducted a systematic review of assessment tools for EBM TTT courses. To summarise and appraise existing assessment methods for teaching the teachers courses in EBM by a systematic review. Methods We searched PubMed, BioMed, EmBase, Cochrane and Eric databases without language restrictions and included articles that assessed its participants. Study selection and data extraction were conducted independently by two reviewers. Results Of 1230 potentially relevant studies, five papers met the selection criteria. There were no specific assessment tools for evaluating effectiveness of EBM TTT courses. Some of the material available might be useful in initiating the development of such an assessment tool. Conclusion There is a need for the development of educationally sound assessment tools for teaching the teachers courses in EBM, without which it would be impossible to ascertain if such courses have the desired effect

Transcriptional Regulation of Cardio-Pulmonary Development

Organogenesis is a complex process, disruption of which results in developmental anomalies. In recent years, genetic dissection of the pathways involved in cardiogenesis, have shown a striking similarity in molecular mechanisms across species. One conserved protein is dHAND, a basic helix-loop-helix (bHLH) transcription factor that is required for normal development of the right ventricle, the pharyngeal arches and limb buds. Loss of dHAND leads to apoptosis in the aforementioned tissues and to embryonic lethality at E10.0. A differential display analysis was performed to identify genes dysregulated in dHAND-/- hearts. Characterization of such genes could potentially shed light on the molecular mechanisms involved in the defects seen in dHAND mutants, while also identifying genes required for normal embryonic development. This thesis represents work on two molecules that were identified in this screen. Bnip3, a hypoxia inducible, pro-apoptotic molecule that can induce mitochondrial damage, was upregulated in the dHAND-/- pharyngeal arches and heart, suggesting a role for mitochondrial damage in the observed apoptosis. I have shown that while Apaf-1, a downstream mediator of mitochondrial-induced apoptosis, is required for the apoptosis observed in dHAND-null pharyngeal and aortic arch mesenchyme, cardiomyocyte apoptosis in dHAND mutants is Apaf-1 independent. Rescue of pharyngeal arches revealed that premature closure of the pharyngeal arch arteries likely contributes to the early lethality observed in dHAND-/- embryos. The mouse ortholog of Bcl-2 associated transcription factor (Btf), which was similar to thyroid hormone receptor associated protein 150 (TRAP150), was down regulated in dHAND mutants. TRAPs are a family of transcriptional co-activators that are required for normal cardiac and embryonic development. Mice lacking Btf showed normal cardiac development, however, the animals had hypercellular lungs and died within 24 hours after birth. Analysis of lung ultrastructure and cell specific markers showed presence of immature secretory cells in the proximal airways of the lung and aberrant proximal-distal patterning. The ectopic presence of stem cell-like proximal epithelial cells (Clara cells) in the distal epithelium may explain the hypercellularity observed in btf-null lungs. These results show that Btf is required for normal maturation and patterning of the pulmonary epithelium and survival of the animal

A Study to Assess the Relationship between Attention Deficit Hyperactivity Disorder and Obstructive Sleep Apnea in Adults

The association between obstructive sleep apnea (OSA) and attention deficit hyperactivity disorder (ADHD) is well-established in children. However, there is a paucity of literature regarding this association in adults. The aim of this study was to determine if ADHD is more common in adult patients with OSA. All patients referred to a sleep center for sleep evaluation were administered the Adult ADHD Self-Report Scale and diagnostic polysomnogram. The ADHD screen is considered positive if 4 of 6 questions in part A of the screening questionnaire were answered abnormally. The study population consisted of 194 participants, predominantly male (62%), Caucasian (54%), and Hispanic (44%). OSA was identified in 160 (83%) of participants, with 116 (60%) having moderate to severe OSA. The ADHD screen was positive in 37 (19%) of participants. There was no significant association between the severity of OSA and presence of ADHD symptoms. Patients with OSA who screened positive for ADHD had higher Epworth Sleepiness Scale scores than those that did not. These data suggest that ADHD is more prevalent in patients with OSA, but do not demonstrate a relationship between OSA severity and ADHD symptoms. Interestingly, sleepiness is more prominent in patients with ADHD

Consumer Prices for Surgical Management of Ankle Arthritis: Limited Availability and Wide Variability.

Background: Healthcare costs for the surgical management of ankle arthritis continue to rise. Patients are generally unaware of the prices of the services they use. Understanding the costs associated with surgical management of ankle arthritis is an important facet of patient care. The purposes of this study were to (1) determine the access to the surgical cost of total ankle arthroplasty (TAAs) and ankle arthrodesis and (2) the variability of the price between the two procedures. Methods: Fifty foot and ankle centers (25 academic, 25 private) that perform TAAs and ankle arthrodeses were contacted using a standardized patient script. The described patient was a 63-year-old man who had failed conservative treatment of ankle arthritis. Each institution was contacted up to three times in an attempt to obtain a full-bundled surgical quote for a TAA and an ankle arthrodesis. Results: Twenty-one centers (42%, 14 academic, 7 private) were able to provide a quote for a TAA and an ankle arthrodesis. The mean bundled price for a TAA was $50,332 (SD ±$25,744), with the mean academic and private center quote being $56,529 and$37,937, respectively. The mean bundled price for an ankle arthrodesis was $41,756 (SD ±$26,033), with the mean academic and private center quote being $48,116 and$29,037, respectively. No statistically significant difference was found between the bundled prices for TAA and ankle arthrodesis. Discussion: This study demonstrated limited availability of consumer prices for TAA and ankle arthrodesis. When comparing different institutions for surgical management of ankle arthritis, there was a wide range of quotes for both TAA and ankle arthrodesis. When comparing the choice of surgical management for ankle arthritis, no statistically significant difference was observed in price between TAA and ankle arthrodesis

Impact of COVID-19 Pandemic on Patients\u27 Perceptions of Safety and Need for Elective Foot and Ankle Surgery in the United States

Background: With the development of the COVID-19 pandemic, elective foot and ankle surgeries were delayed throughout the United States to divert health care resources and limit exposure. Little is known about the impact of COVID-19 on patient\u27s willingness to proceed with elective procedures once restrictions are lifted and factors contributing to such decision. Methods: Patients across 6 US orthopedic institutions who had their elective foot and ankle surgeries cancelled secondary to the pandemic were given a questionnaire. Specifically, patients were asked about their willingness to move forward with surgery once restrictions were lifted and if not why. Pain-level and pain medication use were also assessed. Univariate analysis was used to identify factors that contribute to patient\u27s decisions. Results: A total of 150 patients participated in this study. Twenty-one (14%) opted not to proceed with surgery once restrictions were lifted. Forty-three percent (n = 9) listed concern for COVID infection as the reason; however, 14% of them would proceed if procedures were performed in surgery center. Twenty-nine (19% of the total cohort) patients had increased pain and 11% of patients were taking more pain meds because of the delay to their procedure. Patients who decided not to proceed with surgery reported pain reduction (3% vs 14%) and lower increase in pain medication used (5% vs 12%). Conclusion: COVID-19 has made a significant impact on the health care system. Delay of elective foot and ankle procedures impact patient quality of life and outcomes. Access to surgery centers may provide a partial solution during the pandemic. Level of Evidence: Level III

Image quality in lossy compressed digital mammograms

The substitution of digital representations for analog images provides access to methods for digital storage and transmission and enables the use of a variety of digital image processing techniques, including enhancement and computer assisted screening and diagnosis. Lossy compression can further improve the efficiency of transmission and storage and can facilitate subsequent image processing. Both digitization (or digital acquisition) and lossy compression alter an image from its traditional form, and hence it becomes important that any such alteration be shown to improve or at least not damage the utility of the image in a screening or diagnostic application. One approach to demonstrating in a quantifiable manner that a specific image mode is at least equal to another is by clinical experiment simulating ordinary practice and suitable statistical analysis. In this paper we describe a general protocol for performing such a verification an

Altering Murine Leukemia Virus Integration Through Disruption of the Integrase and BET Protein Family Interaction

We report alterations to the murine leukemia virus (MLV) integrase (IN) protein that successfully result in decreasing its integration frequency at transcription start sites and CpG islands, thereby reducing the potential for insertional activation. The host bromo and extraterminal (BET) proteins Brd2, 3 and 4 interact with the MLV IN protein primarily through the BET protein ET domain. Using solution NMR, protein interaction studies, and next generation sequencing, we showthat the C-terminal tail peptide region ofMLV IN is important for the interaction with BET proteins and that disruption of this interaction through truncation mutations affects the global targeting profile of MLV vectors. The use of the unstructured tails of gammaretroviral INs to direct association with complexes at active promoters parallels that used by histones and RNA polymerase II. Viruses bearingMLV IN C-terminal truncations can provide new avenues to improve the safety profile of gammaretroviral vectors for human gene therapy