301 research outputs found

    Piston Airplane Cruise Performance

    Get PDF
    Ability to achieve efficient range and endurance performance can mean the difference between an uneventful flight and one which ends in anxiety or even tragedy. Beyond the economics of fuel costs, the presence of unexpectedly strong headwinds, navigational error, or deteriorating weather may test the pilot\u27s cruise management capability. The prudent pilot will be prepared by thoroughly understanding the principles underlying cruise performance

    Optimized Engine-Out Procedures to Extend the Range of Jet Transport Airplanes

    Get PDF
    Transoceanic jet transport service, once the exclusive domain of four-engine airplanes, will continue the trend toward two-engine airplanes. This has become possible due to larger, more fuel-efficient and reliable engines and airplanes. Improved reliability demonstrations may soon permit two-engine airplane tracks as far as 120 and 180 minutes flying time from the nearest suitable diversion airport. Although the probability of diversion for a given flight is extremely remote, safety dictates a worst case fuel reserve scenario based on engine-out diversion from the furthest point. This study focuses on engine-out optimum range flight techniques for typical two- and four-engine transports. Various engine-out scenarios for the Boeing 767 and Boeing 747 were investigated using airplane models in wind tunnel experiments. Engine-out specific range improvements up to 9% appear possible through proper techniques of zero sideslip, minimum drag flight. During a rare actual diversion, following proper minimum drag techniques will optimize engine-out specific range and stretch onboard reserves. Similarly, knowledge of such efficiency gains could routinely be translated into reduced diversion fuel reserves--without reduction in safety margin. Reduced contingency fuel translates to some combination of increased payload or improved all-engine cruise economy, thereby increasing operating efficiency and profitability

    New Faculty Mentoring in Respiratory Care Programs

    Get PDF
    Introduction: The purpose of this study was to identify mentoring practices of new faculty members in Commission on Accreditation for Respiratory Care (CoARC) accredited respiratory care programs in the U.S. and to identify the perceptions of program directors regarding the observed impact of program mentoring practices. Methods: The method for the study was quantitative non-experimental survey research. The survey instrument was an electronic questionnaire titled Respiratory Care Faculty (RCF) Mentoring Survey. The 25-item survey was divided into three dimensions: mentoring practices, mentor/mentee relationship, and perceptions of the impact of new faculty mentoring. Of the 410 possible program director participants, 126 (30%) responded to the survey. Data from the survey were used to analyze three primary research questions on four independent variables (12 total research questions). Results: Testing of the null hypotheses associated with the 12 research questions resulted in three significant findings and 9 findings that were not significant. Significant findings included female program directors reported greater opportunities for mentoring within their programs and greater levels of expectation concerning mentoring as compared to male program directors. Program directors from associate degree programs also reported a higher level of expectation concerning mentoring than program directors in bachelor’s degree programs. There was overwhelming agreement regarding the potential impact and benefit of mentoring new faculty to improve job performance, reduce turnover, improve job satisfaction, and organizational commitment. Conclusion: The results of this study may benefit administrators and educators in respiratory care in efforts to support new faculty who possibly feel underprepared or overwhelmed in the new role. Because other allied health fields of study are similar in nature to respiratory care, the findings of the study could have potential implications across a range of health-related professions

    Non-Permanent Pavement Markings in Work Zones

    Get PDF
    DTFH61-89-C-00009This study was conducted to determine the effects of short-term pavement markings on driver performance. Three different marking patterns were tested within the scope of this study: 2-ft stripes with 38-ft gaps (0.61-m stripes with 11.58-m gaps); 4-ft stripes with 36-ft gaps (1.22-m stripes with 10.97-m gaps); and 10-ft stripes with 30-ft gaps (3.05-m stripes with 9.14 gaps) and edgelines. The first two patterns are the temporary markings examined without edgelines while the third scenario is the full complement of markings, including edgelines, recommended in the MUTCD. Data were collected for all three marking patterns during day and night and under dry and wet weather conditions. The data analysis consisted of comparing a number of operational measures collected for the three marking patterns including: 1) lateral placement of the vehicle on the roadway; 2) vehicle speed within the test segment; 3) number of edgeline and lane line encroachments; and 4) number of erratic maneuvers, e.g., sudden directional changes. This final report summarizes the effects on driver performance associated with the different marking patterns tested. The results of this study are presented to help organizations develop guidelines for short-term pavement marking policy

    Poly[aqua(μ-vinyl­phospho­nato)cadmium]

    Get PDF
    The title compound, [Cd(C2H3O3P)(H2O)]n, was obtained from vinyl­phospho­nic acid and cadmium nitrate. The vinyl groups project into the inter­lamellar space and the structure is held together via van der Waals forces. The Cd2+ ion is six-coordinate and the geometry is best described as distorted octa­hedral, with O—Cd—O angles falling within the range 61.72 (13)–101.82 (14)°. Five of the coordinated oxygen atoms originate from the phospho­nate group and the sixth from a bound water molecule. Cd—O distances lie between 2.220 (3) and 2.394 (2) Å. The water mol­ecule is hydrogen bonded to a phospho­nate oxygen atom

    Lack of effect of lowering LDL cholesterol on cancer: meta-analysis of individual data from 175,000 people in 27 randomised trials of statin therapy

    Get PDF
    <p>Background: Statin therapy reduces the risk of occlusive vascular events, but uncertainty remains about potential effects on cancer. We sought to provide a detailed assessment of any effects on cancer of lowering LDL cholesterol (LDL-C) with a statin using individual patient records from 175,000 patients in 27 large-scale statin trials.</p> <p>Methods and Findings: Individual records of 134,537 participants in 22 randomised trials of statin versus control (median duration 4.8 years) and 39,612 participants in 5 trials of more intensive versus less intensive statin therapy (median duration 5.1 years) were obtained. Reducing LDL-C with a statin for about 5 years had no effect on newly diagnosed cancer or on death from such cancers in either the trials of statin versus control (cancer incidence: 3755 [1.4% per year [py]] versus 3738 [1.4% py], RR 1.00 [95% CI 0.96-1.05]; cancer mortality: 1365 [0.5% py] versus 1358 [0.5% py], RR 1.00 [95% CI 0.93–1.08]) or in the trials of more versus less statin (cancer incidence: 1466 [1.6% py] vs 1472 [1.6% py], RR 1.00 [95% CI 0.93–1.07]; cancer mortality: 447 [0.5% py] versus 481 [0.5% py], RR 0.93 [95% CI 0.82–1.06]). Moreover, there was no evidence of any effect of reducing LDL-C with statin therapy on cancer incidence or mortality at any of 23 individual categories of sites, with increasing years of treatment, for any individual statin, or in any given subgroup. In particular, among individuals with low baseline LDL-C (<2 mmol/L), there was no evidence that further LDL-C reduction (from about 1.7 to 1.3 mmol/L) increased cancer risk (381 [1.6% py] versus 408 [1.7% py]; RR 0.92 [99% CI 0.76–1.10]).</p> <p>Conclusions: In 27 randomised trials, a median of five years of statin therapy had no effect on the incidence of, or mortality from, any type of cancer (or the aggregate of all cancer).</p&gt

    La comunicazione interculturale e l’approccio comunicativo: dall’idea allo strumento

    Get PDF
    il saggio si inserisce in un filone di ricerca aperto nel 199 e proseguito con saggi e volumi: in questo caso di descrive e discute la progettazione di un passo fondamentale, dall'elaborazione teorica del modello di riferimento alla traduzione di tale modello in strumento operativo per la consultazione e la didattica

    Survey of childhood empyema in Asia: Implications for detecting the unmeasured burden of culture-negative bacterial disease

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Parapneumonic empyema continues to be a disease of significant morbidity and mortality among children despite recent advances in medical management. To date, only a limited number of studies have assessed the burden of empyema in Asia.</p> <p>Methods</p> <p>We surveyed medical records of four representative large pediatric hospitals in China, Korea, Taiwan and Vietnam using <it>ICD</it>-10 diagnostic codes to identify children <16 years of age hospitalized with empyema or pleural effusion from 1995 to 2005. We also accessed microbiology records of cultured empyema and pleural effusion specimens to describe the trends in the epidemiology and microbiology of empyema.</p> <p>Results</p> <p>During the study period, we identified 1,379 children diagnosed with empyema or pleural effusion (China, n = 461; Korea, n = 134; Taiwan, n = 119; Vietnam, n = 665). Diagnoses of pleural effusion (n = 1,074) were 3.5 times more common than of empyema (n = 305), although the relative proportions of empyema and pleural effusion noted in hospital records varied widely between the four sites, most likely because of marked differences in coding practices. Although pleural effusions were reported more often than empyema, children with empyema were more likely to have a cultured pathogen. In addition, we found that median age and gender distribution of children with these conditions were similar across the four countries. Among 1,379 empyema and pleural effusion specimens, 401 (29%) were culture positive. <it>Staphylococcus aureus </it>(n = 126) was the most common organism isolated, followed by <it>Streptococcus pneumoniae </it>(n = 83), <it>Pseudomonas aeruginosa </it>(n = 37) and <it>Klebsiella </it>(n = 35) and <it>Acinetobacter </it>species (n = 34).</p> <p>Conclusion</p> <p>The age and gender distribution of empyema and pleural effusion in children in these countries are similar to the US and Western Europe. <it>S. pneumoniae </it>was the second leading bacterial cause of empyema and pleural effusion among Asian children. The high proportion of culture-negative specimens among patients with pleural effusion or empyema suggests that culture may not be a sufficiently sensitive diagnostic method to determine etiology in the majority of cases. Future prospective studies in different countries would benefit from standardized case definitions and coding practices for empyema. In addition, more sensitive diagnostic methods would improve detection of pathogens and could result in better prevention, treatment and outcomes of this severe disease.</p

    Changing Epidemiology of Serious Bacterial Infections in Febrile Infants without Localizing Signs

    Get PDF
    Objective: Historically, management of infants with fever without localizing signs (FWLS) has generated much controversy, with attempts to risk stratify based on several criteria. Advances in medical practice may have altered the epidemiology of serious bacterial infections (SBIs) in this population. We conducted this study to test the hypothesis that the rate of SBIs in this patient population has changed over time. Patients and Methods: We performed a retrospective review of all infants meeting FWLS criteria at our institution from 1997–2006. We examined all clinical and outcome data and performed statistical analysis of SBI rates and ampicillin resistance rates. Results: 668 infants met criteria for FWLS. The overall rate of SBIs was 10.8%, with a significant increase from 2002–2006 (52/ 361, 14.4%) compared to 1997–2001 (20/307, 6.5%) (p = 0.001). This increase was driven by an increase in E. coli urinary tract infections (UTI), particularly in older infants (31–90 days). Conclusions: We observed a significant increase in E. coli UTI among FWLS infants with high rates of ampicillin resistance. The reasons are likely to be multifactorial, but the results themselves emphasize the need to examine urine in all febrile infants,90days and consider local resistance patterns when choosing empiric antibiotics
    corecore