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

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

A web-based library consult service for evidence-based medicine: Technical development

BACKGROUND: Incorporating evidence based medicine (EBM) into clinical practice requires clinicians to learn to efficiently gain access to clinical evidence and effectively appraise its validity. Even using current electronic systems, selecting literature-based data to solve a single patient-related problem can require more time than practicing physicians or residents can spare. Clinical librarians, as informationists, are uniquely suited to assist physicians in this endeavor. RESULTS: To improve support for evidence-based practice, we have developed a web-based EBM library consult service application (LCS). Librarians use the LCS system to provide full text evidence-based literature with critical appraisal in response to a clinical question asked by a remote physician. LCS uses an entirely Free/Open Source Software platform and will be released under a Free Software license. In the first year of the LCS project, the software was successfully developed and a reference implementation put into active use. Two years of evaluation of the clinical, educational, and attitudinal impact on physician-users and librarian staff are underway, and expected to lead to refinement and wide dissemination of the system. CONCLUSION: A web-based EBM library consult model may provide a useful way for informationists to assist clinicians, and is feasible to implement

Gene Expression Signature of DMBA-Induced Hamster Buccal Pouch Carcinomas: Modulation by Chlorophyllin and Ellagic Acid

Chlorophyllin (CHL), a water-soluble, semi-synthetic derivative of chlorophyll and ellagic acid (EA), a naturally occurring polyphenolic compound in berries, grapes, and nuts have been reported to exert anticancer effects in various human cancer cell lines and in animal tumour models. The present study was undertaken to examine the mechanism underlying chemoprevention and changes in gene expression pattern induced by dietary supplementation of chlorophyllin and ellagic acid in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model by whole genome profiling using pangenomic microarrays. In hamsters painted with DMBA, the expression of 1,700 genes was found to be altered significantly relative to control. Dietary supplementation of chlorophyllin and ellagic acid modulated the expression profiles of 104 and 37 genes respectively. Microarray analysis also revealed changes in the expression of TGFβ receptors, NF-κB, cyclin D1, and matrix metalloproteinases (MMPs) that may play a crucial role in the transformation of the normal buccal pouch to a malignant phenotype. This gene expression signature was altered on treatment with chlorophyllin and ellagic acid. Our study has also revealed patterns of gene expression signature specific for chlorophyllin and ellagic acid exposure. Thus dietary chlorophyllin and ellagic acid that can reverse gene expression signature associated with carcinogenesis are novel candidates for cancer prevention and therapy

A Lagrangian Formulation Of High Rate Quantization

The asymptotic optimal performance of variable-rate vector quantizers of fixed dimension and large rate was first developed in a rigorous fashion by Paul Zador. Subsequent design algorithms for such compression codes used a Lagrangian formulation in order to generalize Lloyd's classic quantizer optimization algorithm to variable rate codes. This formulation has been subsequently adopted in a variety of practical systems including rate-optimized streaming video. We describe a Lagrangian formulation of Zador's variable-rate quantization results and apply it to estimate Zador's constant using the generalized Lloyd algorithm

Update on clinical trials for the prevention of acute kidney injury in patients undergoing cardiac surgery

Background: Effective therapeutic agents for the prevention and treatment of acute kidney injury (AKI) after cardiac surgery remain elusive despite the tremendous advances in surgical techniques, technology, and understanding of disease processes. Recent developments and their effect on the incidence of AKI after cardiac surgery are discussed. Data Sources: Published clinical trials in PubMed, strength of evidence assessed by the guidelines of the American Family Physicians. Conclusions: The definition of AKI has changed, and the focus of interventions has shifted from treatment to prevention to recovery from AKI. Antioxidants and biological agents have been added to classic armaments of hydration and diuretics in addition to tighter metabolic control to prevent AKI. Although the treatment options remain unsatisfactory, a lot of progress nevertheless continues to be made in the prevention and treatment of AKI. © 2013 Elsevier Inc

Update On Clinical Trials For The Prevention Of Acute Kidney Injury In Patients Undergoing Cardiac Surgery

Background: Effective therapeutic agents for the prevention and treatment of acute kidney injury (AKI) after cardiac surgery remain elusive despite the tremendous advances in surgical techniques, technology, and understanding of disease processes. Recent developments and their effect on the incidence of AKI after cardiac surgery are discussed. Data Sources: Published clinical trials in PubMed, strength of evidence assessed by the guidelines of the American Family Physicians. Conclusions: The definition of AKI has changed, and the focus of interventions has shifted from treatment to prevention to recovery from AKI. Antioxidants and biological agents have been added to classic armaments of hydration and diuretics in addition to tighter metabolic control to prevent AKI. Although the treatment options remain unsatisfactory, a lot of progress nevertheless continues to be made in the prevention and treatment of AKI. © 2013 Elsevier Inc