Best Constants for the Riesz Projection

AbstractWe prove the following inequality with a sharp constant,‖P+f‖L p(T)⩽csc πp ‖f‖Lp(T),f∈Lp(T),where 1<p<∞, and P+: Lp(T)→Hp(T) is the Riesz projection onto the Hardy space Hp(T) on the unit circle T. (In other words, the “angle” between the analytic and co-analytic subspaces of Lp(T) equals π/p* where p*=max (p, pp−1).) This was conjectured in 1968 by I. Gohberg and N. Krupnik. We also prove an analogous inequality in the nonperiodic case where P+f=F−1 (χR+Ff) is the half-line Fourier multiplier on R. Similar weighted inequalities with sharp constants for Lp(R, |x|α), −1<α<p−1, are obtained. In the multidimensional case, our results give the norm of the half-space Fourier multiplier on R

How often is a work-up for Legionella pursued in patients with pneumonia? A retrospective study

<p>Abstract</p> <p>Background</p> <p>It is unclear how often patients with pneumonia are assessed for <it>Legionella </it>in endemic areas. Additionally, the sensitivity of the IDSA/ATS criteria for recommended <it>Legionella </it>testing is undefined.</p> <p>Methods</p> <p>We performed a single-center, retrospective study of patients diagnosed with <it>Legionella </it>pneumonia at our hospital to determine: 1) how often <it>Legionella </it>diagnostic testing is obtained on patients with pneumonia at the time of hospitalization or when pneumonia developed during hospitalization; and 2) how often patient's with <it>Legionella </it>pneumonia met at least one of the five criteria in the IDSA/ATS guidelines recommending a work-up for <it>Legionella</it>. Patients with <it>Legionella </it>pneumonia were identified using an infection control software program. Medical records of these patients were then reviewed.</p> <p>Results</p> <p>Thirty-five percent of patients with a discharge diagnosis of pneumonia had <it>Legionella </it>urine antigen testing and/or a <it>Legionella </it>culture performed. Forty-four percent of patients who had a bronchoscopic specimen sent for microbiologic testing had a <it>Legionella </it>culture performed on the bronchoscopic specimen and/or <it>Legionella </it>urine antigen testing. Of 37 adult patients with <it>Legionella </it>pneumonia, 22 (59%) met the IDSA-ATS criteria recommending <it>Legionella </it>testing.</p> <p>Conclusion</p> <p>Following current recommendations for <it>Legionella </it>testing missed 41% of <it>Legionella </it>cases in adults in our single-center study. A work-up for <it>Legionella </it>(i.e., urine antigen test and/or culture) was performed in less than half of patients who have a bronchoscopic specimen sent for microbiologic testing.</p

Addressing decontaminated respirators: Some methods appear to damage mask integrity and protective function

Decontamination of N95 respirators is being used by clinicians in the face of a global shortage of these devices. Some treatments for decontamination, such as some vaporized hydrogen peroxide methods or ultraviolet methods, had no impact on respiratory performance, while other treatments resulted in substantial damage to masks

Statin Use and Risk of Sepsis After Percutaneous Nephrolithotomy

Purpose: To examine the association between statin medication use and sepsis risk after percutaneous nephrolithotomy (PCNL). Materials and Methods: Using medical claims data, we identified working-age adults with urinary stone disease who were treated with PCNL. Among this cohort, we determined which patients had a prescription fill for a statin agent that encompassed their surgery date. We then fitted logistic regression models to examine for differences in rates of postoperative sepsis between statin users and nonusers. In addition, we evaluated the frequency of nonfebrile urinary tract infections (UTIs) and intensive care unit (ICU) services utilization and hospital length of stay (LOS) as a function of statin use. Results: During the study period, at total of 2046 patients underwent PCNL, 382 (18.7%) of whom had a prescription fill for a statin agent preceding their surgery. The overall rate of sepsis in this population was 3.8%. After adjusting for patient health status and sociodemographic factors, the rate of postoperative sepsis was comparable between statin users and nonusers (5.3% vs 3.5%, respectively; P=0.105). In addition, UTI and ICU utilization rates did not relate to statin use (P>0.05 for all associations). Adjusted hospital LOS was shorter among statin users, but the difference was clinically trivial (3.6 vs 4.1 days; P=0.007). Conclusions: Statin use is not associated with reductions in postoperative sepsis, nonfebrile UTIs, ICU utilization, or hospital LOS after PCNL. To increase the safety of PCNL, urologists will have to consider other processes of care (e.g., clinical care pathways).Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140081/1/end.2015.0042.pd

Computer simulation as a component of catheter-based training

IntroductionComputer simulation has been used in a variety of training programs, ranging from airline piloting to general surgery. In this study we evaluate the use of simulation to train novice and advanced interventionalists in catheter-based techniques.MethodsTwenty-one physicians underwent evaluation in a simulator training program that involved placement of a carotid stent. Five participants were highly experienced in catheter-based techniques (>300 percutaneous cases), including carotid angioplasty and stenting (CAS); the remaining 16 participants were interventional novices (<5 percutaneous cases). The Procedicus VIST simulator, composed of real-time vascular imaging simulation software and a tactile interface coupled to angiographic catheters and guide wires, was used. After didactic instruction regarding CAS and use of the simulator, each participant performed a simulated CAS procedure. The participant's performance was supervised and evaluated by an expert interventionalist on the basis of 50 specific procedural steps with a maximal score of 100. Specific techniques of guide wire and catheter manipulation were subjectively assessed on a scale of 0 to 5 points based on ability. After evaluation of the initial simulated CAS procedure, each participant received a minimum of 2 hours of individualized training by the expert interventionalist, with the VIST simulator. Each participant then performed a second simulated CAS procedure, which was graded with the same scale. After completion, participants assessed the training program and its utility via survey questionnaire.ResultsThe average simulated score for novice participants after the training program improved significantly from 17.8 ± 15.6 to 69.8 ± 9.8 (P < .01), time to complete simulation decreased from 44 ± 10 minutes to 30 ± 8 minutes (P < .01), and fluoroscopy time decreased from 31 ± 7 minutes to 23 ± 7 minutes (P < .01). No statistically significant difference in score, total time, or fluoroscopy time was noted for experienced interventionalists. Improvement was noted in guide wire and catheter manipulation skills in novices.. Analysis of survey data from experienced interventionalists indicated that the simulated clinical scenarios were realistic and that the simulator could be a valuable tool if clinical and tactile feedback were improved. Novices also thought the simulated training was a valuable experience, and desired further training time.ConclusionsAn endovascular training program using the Procedicus VIST haptic simulator resulted in significant improvement in trainee facility with catheter-based techniques in a simulated clinical setting. Novice participants derived the greatest benefit from simulator training in a mentored program, whereas experienced interventionalists did not seem to derive significant benefit

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo