5,108 research outputs found
Shock fitting applied to the prediction of high-speed rotor noise
A shock fitting method applied to the transonic small disturbance (TSD) potential equation is described. This method is then applied to a simple, two dimensional (2-D) rotating disturbance which is analogous to a shock radiating from the tip of a rotor blade in high speed hover. A comparison is made between the results of this method and the more standard shock capturing method. This comparison makes it clear that the effect of the results on the acoustic signature of the 2-D model is significant, and similar results can be expected when the method is extended to the three dimensional (3-D) case
Alumina bearing in gas-lubricated gyros
Friction and wear properties of alumina bearings for use in gas-lubricated gyroscope
Experiment in beef production.
This bulletin gives the result of a year’s feeding test with steers of beef and dairy type; it also includes the slaughter test on the same animals, conducted in January, 1904, and a meat demonstration by Mr. John Gosling. While the results of the slaughter test are properly a part of the experiment, it has been deemed advisable to treat them somewhat distinctly. The data bearing on the differences in feeding and gaining capacity are therefore treated in the first part of the bulletin, and the results of the slaughter test, with Mr. Gosling’s explanations, in the latter part
The feeding value of soft corn for beef production.
The early fall frosts affect the corn crop in the central and northern states more or less each year. The crop of 1902 was seriously damaged in many sections by the early September frost. The yield per acre was very much reduced. The percentage of marketable corn was a variable quantity. In some sections practically all of the corn was worthless from a regular market standpoint, due to the fact that it was too soft and watery for shipping purposes.
This presented a serious condition of affairs. There was then but one way to utilize that portion of the crop which was soft and immature. It must be fed to live stock
Gestational dating by metabolic profile at birth: a California cohort study.
BackgroundAccurate gestational dating is a critical component of obstetric and newborn care. In the absence of early ultrasound, many clinicians rely on less accurate measures, such as last menstrual period or symphysis-fundal height during pregnancy, or Dubowitz scoring or the Ballard (or New Ballard) method at birth. These measures often underestimate or overestimate gestational age and can lead to misclassification of babies as born preterm, which has both short- and long-term clinical care and public health implications.ObjectiveWe sought to evaluate whether metabolic markers in newborns measured as part of routine screening for treatable inborn errors of metabolism can be used to develop a population-level metabolic gestational dating algorithm that is robust despite intrauterine growth restriction and can be used when fetal ultrasound dating is not available. We focused specifically on the ability of these markers to differentiate preterm births (PTBs) (<37 weeks) from term births and to assign a specific gestational age in the PTB group.Study designWe evaluated a cohort of 729,503 singleton newborns with a California birth in 2005 through 2011 who had routine newborn metabolic screening and fetal ultrasound dating at 11-20 weeks' gestation. Using training and testing subsets (divided in a ratio of 3:1) we evaluated the association among PTB, target newborn characteristics, acylcarnitines, amino acids, thyroid-stimulating hormone, 17-hydroxyprogesterone, and galactose-1-phosphate-uridyl-transferase. We used multivariate backward stepwise regression to test for associations and linear discriminate analyses to create a linear function for PTB and to assign a specific week of gestation. We used sensitivity, specificity, and positive predictive value to evaluate the performance of linear functions.ResultsAlong with birthweight and infant age at test, we included 35 of the 51 metabolic markers measured in the final multivariate model comparing PTBs and term births. Using a linear discriminate analyses-derived linear function, we were able to sort PTBs and term births accurately with sensitivities and specificities of ≥95% in both the training and testing subsets. Assignment of a specific week of gestation in those identified as PTBs resulted in the correct assignment of week ±2 weeks in 89.8% of all newborns in the training and 91.7% of those in the testing subset. When PTB rates were modeled using the metabolic dating algorithm compared to fetal ultrasound, PTB rates were 7.15% vs 6.11% in the training subset and 7.31% vs 6.25% in the testing subset.ConclusionWhen considered in combination with birthweight and hours of age at test, metabolic profile evaluated within 8 days of birth appears to be a useful measure of PTB and, among those born preterm, of specific week of gestation ±2 weeks. Dating by metabolic profile may be useful in instances where there is no fetal ultrasound due to lack of availability or late entry into care
Selected College Students\u27 Knowledge and Perceptions of Biotechnology Issues Reported in the Mass Media
The purpose of this study was to determine college students\u27 awareness of and attitudes toward biotechnology issues reported in the mass media. Future agricultural communicators (N = 330) representing 11 land-grant universities in 10 states recorded their knowledge and perceptions of biotechnology issues as reported in the mass media. Respondents were mostly seniors (46%), female (55%), and considered themselves 8 average students (60%). Students achieved only 30% correct responses (M = 3.05) in a knowledge assessment of biotechnology practices, illustrating a lack of knowledge. However, nearly 84% of the respondents perceived their level of knowledge as average to high (24% perceived they possessed above-average scientific knowledge). Future agricultural communicators were somewhat accepting of biotechnology practices for genetically modified organisms involving plant life (M = 3.28), but viewed these same practices as somewhat unacceptable for use on humans (M = 1.84). Significant, low positive relationships existed between respondents\u27 perceived and assessed levels ofbiotechnology knowledge (r = .17) and between their assessed knowledge and acceptance of biotechnology practices (r = .16). Selected college students in the agricultural sciences have much less knowledge about biotechnology practices than what they believed to possess. Although correctable through increased study of biotechnology, this finding may pose serious problems for students choosing to communicate the science of biotechnology issues in the mass media. Agricultural communications faculty nationwide should analyze their curricula to determine if students are being given the opportunity to study biotechnology issues while learning how to communicate it to a larger audience
UAV Model-based Flight Control with Artificial Neural Networks: A Survey
Model-Based Control (MBC) techniques have dominated flight controller designs for Unmanned Aerial Vehicles (UAVs). Despite their success, MBC-based designs rely heavily on the accuracy of the mathematical model of the real plant and they suffer from the explosion of complexity problem. These two challenges may be mitigated by Artificial Neural Networks (ANNs) that have been widely studied due to their unique features and advantages in system identification and controller design. Viewed from this perspective, this survey provides a comprehensive literature review on combined MBC-ANN techniques that are suitable for UAV flight control, i.e., low-level control. The objective is to pave the way and establish a foundation for efficient controller designs with performance guarantees. A reference template is used throughout the survey as a common basis for comparative studies to fairly determine capabilities and limitations of existing research. The end-result offers supported information for advantages, disadvantages and applicability of a family of relevant controllers to UAV prototypes
Evaluation of care and treatment clinics using a four-year retrospective cohort of patients receiving anti-retroviral therapy in Mbeya Region, Tanzania
Evaluations of sub-national anti-retroviral therapy (ART) programmes’ performance are important to support regional programme planning and epidemic response. We constructed a four-year retrospective cohort of clients from 10 care and treatment clinics (CTC) in the Mbeya region of Tanzania using routinely collected data from patients initiating ART between January 1, 2008 and March 31, 2012. Our primary outcomes were mortality rate and lost to follow up. We calculated ART coverage based on regional prevalence estimates and used medical cards, drug registers and quarterly reports to assess data quality. We enrolled 17,813 participants into the cohort. More patients initiated ART at WHO stages 3 (58.9%), and at CD4 cell counts between 50-199 cells/µl (56%). The proportion of patients initiating ARTs at a CD4 counts <50 cells/µl decreased from 40.7% in 2008 to 33.8% in 2012 (p-value <0.001). A total of 10,155 (57.0%) patients were lost to follow up (LTFU) during the 4 years of follow up; 59.2% were female. The overall mortality rate was 17.8 per 1000 person years; the six-month mortality was 6.2 per 1000 person years. The risk of mortality for patients at WHO stage III and IV was more than twice as high (hazard ratio [HR] 2.15; 95% confidence interval [CI], 1.05-4.39 and HR 2.29; 95% CI, 1.39-6.37, respectively) as compared to stage I and II. Those patients initiating ART with CD4 cell count between 50 and 199 cells/µl had significantly lower hazard of death compared to those initiating ART with CD4 cells counts <50 cells/µl (HR 0.51, 95% CI 0.34-0.78). In conclusion, during the study, a high proportion of patients were lost to follow up, and the majority of them were female. Most patients initiated ARTs at lower CD4 count (<200 cells/mm3) and at WHO stages III and IV, and they had higher risk of mortality compared to those initiated at higher CD4 counts and WHO stage I and II. Emphasis needs to be placed on strategies of early diagnosis of HIV infection, prompt initiation of ART, and support for ART adherence to minimise lost to follow up
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