Modeling Passenger Travel and Delays in the National Air Transportation System

Many of the existing methods for evaluating an airline's on-time performance are based on flight-centric measures of delay. However, recent research has demonstrated that passenger delays depend on many factors in addition to flight delays. For instance, significant passenger delays result from flight cancellations and missed connections, which themselves depend on a significant number of factors. Unfortunately, lack of publicly available passenger travel data has made it difficult for researchers to explore the nature of these relationships. In this paper, we develop methodologies to model historical travel and delays for U.S. domestic passengers. We develop a multinomial logit model for estimating historical passenger travel and extend a previously developed greedy reaccommodation heuristic for estimating the resulting passenger delays. We report and analyze the estimated passenger delays for calendar year 2007, developing insights into factors that affect the performance of the National Air Transportation System in the United States.United States. Federal Aviation Administration. National Center for Excellence for Aviation Operations Researc

Winter grazing management

Why winter grazing? Beef cow herd and sheep flock records show that winter feeding costs are livestock producers\u27 single largest production expense. Managing through winter weather while keeping feeding costs low is an essential part of maintaining a profitable operation. Iowa\u27s climate generally allows forage growth only during a 7-to-8 month period. Extending the grazing of this forage--even an extra 3 or 4 weeks in late autumn and winter--is an economical way to maintain or increase livestock profitability. Some producers extend the grazing season by using stockpiled forage, whereas others use crop residue, and many combine the use of stockpiled forage and crop residue. Producers who graze livestock during the winter need to know techniques that optimize their resources, provide consistent, high-quality forage, and conserve soi

Endothelin-Stimulated Capacitative Calcium Entry in Enteric Glial Cells: Synergistic Effects of Protein Kinase C Activity and Nitric Oxide

Depletion of intracellular calcium stores by agonist stimulation is coupled to calcium influx across the plasma membrane, a process termed capacitative calcium entry. Capacitative calcium entry was examined in cultured guinea pig enteric glial cells exposed to endothelin 3. Endothelin 3 (10 n M ) caused mobilization of intracellular calcium stores followed by influx of extracellular calcium. This capacitative calcium influx was inhibited by Ni 2+ (89 ± 2%) and by La 3+ (78 ± 2%) but was not affected by L-, N-, or P-type calcium channel blockers. Chelerythrine, a specific antagonist of protein kinase C, dose-dependently inhibited capacitative calcium entry. The nitric oxide synthase inhibitor N G -nitro-l-arginine decreased calcium influx in a dose-dependent manner. The combination of chelerythrine and N G -nitro-l-arginine produced synergistic inhibitory effects. Capacitative calcium entry occurs in enteric glial cells via lanthanum-inhibitable channels through a process regulated by protein kinase C and nitric oxide.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65161/1/j.1471-4159.1998.71010205.x.pd

Reflux related hospital admissions after fundoplication in children with neurological impairment: retrospective cohort study

Objective To examine the impact of fundoplication on reflux related hospital admissions for children with neurological impairment

Musculoskeletal deformities following repair of large congenital diaphragmatic hernias

Split-abdominal wall muscle flap Purpose: Large congenital diaphragmatic hernias (CDH) can be repaired with either a muscle flap or prosthetic patch. The purpose of this study was to assess the frequency and severity of scoliosis, chest wall, and abdominal wall deformities following these repairs. Methods: Neonates who underwent CDH repair (1989-2012) were retrospectively reviewed. We then validated our retrospective review by comparing results of a focused radiologic evaluation and clinical examination of patients with large defects seen in prospective follow-up clinic. Tests for association were made using Fisher's exact test. Results: 236 patients survived at least 1 year. Of these patients, 30 had a muscle flap, and 13 had a patch repair. Retrospectively, we identified pectus in 9% of primary repairs, 47% of flap repairs, and 54% of patch repairs. We identified scoliosis in 7% of primary repairs, 13% of flap repairs, and 15% of patch repairs. Prospectively, 75% of flap patients and 67% of patch patients had pectus and 13% of flap patients and 33% of patch patients had scoliosis. There was no significant difference between flap and patch patients. Conclusions: Scoliosis and pectus deformity were common in children with large CDH. The operative technique did not appear to affect the incidence of subsequent skeletal deformity. © 2014 Elsevier Inc. All rights reserved. Large congenital diaphragmatic hernias (CDHs) require repair with either a patch or an autologous tissue transfer. Repair with a prosthetic patch is the technique used by most surgeons Methods Study population After obtaining approval from the Institutional Review Board, a retrospective review of all children with CDH repair at our regional tertiary care children's hospital from 1989 to 2012 was performed. The patients were categorized by the technique of their repair. Repair types included primary repair, split abdominal wall muscle flap and synthetic patch. Paper and electronic medical records were reviewed to obtain demographic data, and diagnosis of skeletal deformities as well as any treatment for the skeletal deformities. Electronic charts were searched for the key words "pectus" and "scoliosis," and those specific notes were reviewed. These diagnoses were made by a variety of physicians including radiologists, orthopedists and primary care physicians and were not always confirmed by a focused follow-up visit by a pediatric surgeon. In order to check the validity of our retrospective review, patients with large defects were seen prospectively for focused follow-up and a single pediatric radiologist (G.H.) reviewed the most current chest radiograph to evaluate for scoliosis greater than 10 degrees. The results of follow-up were correlated with our retrospective review

Minimally Invasive Mitral Valve Surgery III: Training and Robotic-Assisted Approaches.

Minimally invasive mitral valve operations are increasingly common in the United States, but robotic-assisted approaches have not been widely adopted for a variety of reasons. This expert opinion reviews the state of the art and defines best practices, training, and techniques for developing a successful robotics program

Minimally Invasive Mitral Valve Surgery I: Patient Selection, Evaluation, and Planning.

Widespread adoption of minimally invasive mitral valve repair and replacement may be fostered by practice consensus and standardization. This expert opinion, first of a 3-part series, outlines current best practices in patient evaluation and selection for minimally invasive mitral valve procedures, and discusses preoperative planning for cannulation and myocardial protection

Minimally Invasive Mitral Valve Surgery II: Surgical Technique and Postoperative Management.

Techniques for minimally invasive mitral valve repair and replacement continue to evolve. This expert opinion, the second of a 3-part series, outlines current best practices for nonrobotic, minimally invasive mitral valve procedures, and for postoperative care after minimally invasive mitral valve surgery

Surgical protocol violations in children with renal tumors provides an opportunity to improve pediatric cancer care: a report from the Children’s Oncology Group

BackgroundThe purpose of this study was to evaluate the frequency and characteristics of surgical protocol violations (SPVs) among children undergoing surgery for renal tumors who were enrolled on the Children’s Oncology Group (COG) renal tumor biology and classification study AREN03B2.MethodsAREN03B2 was opened in February 2006, and as on March 31, 2013, there were 3,664 eligible patients. The surgical review forms for 3,536 patients with unilateral disease were centrally reviewed for SPVs. The frequency, type, number of violations, institutional prevalence, and quartiles for SPVs were assessed.ResultsOf the 3,536 patients, there were a total of 505 with at least one SPV (564 total SPVs reported), for an overall incidence of 14.28%. The types of SPVs included a lack of lymph node sampling in 365 (64.7%), avoidable spill in 61 (10.8%), biopsy immediately before nephrectomy in 89 (15.8%), an incorrect abdominal incision in 32 (5.7%), and unnecessary resection of organs in 17 (3.0%). The SPVs occurred in 163 of 215 participating institutions (75.8%). For centers with at least one SPV, the mean number of SPVs reported was 3.10 ± 2.39 (mean ± standard deviation). The incidence of protocol violation per institution ranged from 0 to 67%. Centers with an average of ≤1 case/year had an incidence of SPVs of 12.2 ± 3.8%, those with an average of >1 to 0.05).ConclusionsSPVs that potentially result in additional exposure to chemotherapy and radiation therapy are not uncommon in children undergoing resection of renal malignancies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134088/1/pbc26083.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134088/2/pbc26083_am.pd