Robust Nonnested Testing for Ordinary Least Squares Regression When Some of the Regressors are Lagged Dependent Variables

The problem of testing nonnested regression models that include lagged values of the dependent variable as regressors is discussed. It is argued that it is essential to test for error autocorrelation if ordinary least squares and the associated J and F tests are to be used. A heteroskedasticity-robust joint test against a combination of the artificial alternatives used for autocorrelation and nonnested hypothesis tests is proposed. Monte Carlo results indicate that implementing this joint test using a wild bootstrap method leads to a well-behaved procedure and gives better control of finite sample significance levels than asymptotic critical values.nonnested models, heteroskedasticity-robust, wild bootstrap

Magnetoplasmons in magic-angle twisted bilayer graphene

The magic-angle twisted bilayer graphene (MATBLG) has been demonstrated to exhibit exotic physical properties due to the special flat bands. However, exploiting the engineering of such properties by external fields is still in it infancy. Here we show that MATBLG under an external magnetic field presents a distinctive magnetoplasmon dispersion, which can be significantly modified by transferred momentum and charge doping. Along a wide range of transferred momentum, there exist special pronounced single magnetoplasmon and horizontal single-particle excitation modes near charge neutrality. We provide an insightful discussion of such unique features based on the electronic excitation of Landau levels quantized from the flat bands and Landau damping. Additionally, charge doping leads to peculiar multiple strong-weight magnetoplasmons. These characteristics make MATBLG a favorable candidate for plasmonic devices and technology applications

Diagnostic utility of abdominal ultrasound in the evaluation of abdomino-pelvic lesions at Bugando Medical Centre in Mwanza, Tanzania

Background: Despite the fact that abdominal ultrasound has been widely used in many centres in Tanzania as a primary diagnostic imaging for patients with abdomino-pelvic lesions, its diagnostic utility has not yet been assessed in Tanzania, and therefore its use as an alternative diagnostic tool in patients with abdomino-pelvic lesions is not justified. This study aimed to determine the utility of abdominal ultrasound in the diagnosis of abdomino-pelvic lesions in our local setting.Methods: This was a cross sectional study to evaluate the diagnostic utility of abdominal ultrasound in patients presenting with abdomino-pelvic lesions at Bugando Medical Centre between January 2017 and July 2017. Abdominal ultrasonographic findings were cross-tabulated against operative findings (the gold standard). Then, the sensitivity, specificity, accuracy, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and accuracy were calculated to determine the diagnostic utility of abdominal ultrasound.Results: A total of 146 patients (M: F ratio = 1: 2.2) were studied. The mean age at diagnosis was 39.3 years. The diagnostic utility of abdominal ultrasound in terms of sensitivity, specificity, PPV, NPV and accuracy were 39.4-100%, 0-100%, 64.7-100%, 0-100% and 40.8-100% respectively.  The kappa statistic (қ) showed good to excellent agreement with the operative findings, the gold standard (қ = 0.75-1.00).Conclusion: The diagnostic utility of abdominal ultrasound in detecting abdomino-pelvic lesions is much lower than that seen in developed countries, hence, abdominal ultrasound is not a reliable tool in detecting abdomino-pelvic lesions at Bugando Medical Centre and therefore its use should be supplemented with abdominal CT scan in selected cases

A possible resolution of the CDF psi^prime anomaly

We consider the contribution of radially excited 2^3P_{1,2} states to psi^prime production at the Tevatron energy. Production of these states via the conventional gluon fusion mechanism and via gluon and charm quark fragmentation processes is considered. We find that it is possible to account for the data on psi^prime production from the CDF experiment, by taking into account the decays of these 2^3P_{1,2} states into psi^prime.Comment: 8 pages + 1 figure (available upon request), CERN-TH.7434/9

Shape switching from 2D to 3D via FDM

3D printing that allow shape switching from 2D to 3D via FDMBachelor of Engineering (Mechanical Engineering

The risk of users’ negative behaviours influence on information security compliance policy in organizations

The focus of information security has traditionally been on technological issues, and organizations have long been using technological controls to protect information assets. In spite of all these efforts there is still a significant level of non-compliance to information security compliance by employees in organizations. Information security also comes in non-technical forms that the technical controls cannot fully address without the cooperation of employees. This study investigates the factors influencing end-user resistance to information security compliance in organizations. The study reviews the related literature to understand why and how end-user resistance develops. The paper adopted the qualitative research methodology which enabled the researcher to investigate end-users’ attitudes towards information security compliance in the organization; using a single case study. The study results indicate that end-user resistance is mainly a result of lack of training and awareness of information security policies in the organization. The study contributed to our understanding of end-user resistance of information security in organizations. It also contributed to the emerging body of knowledge on behavioural issues of information security in organization

Soils of the Blackland Experiment Station.

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Gall stones and mortality: A study of all gall stone related deaths in a single health district

In a prospective study of gall stone related deaths in a single Health District, the biliary tract was examined at necropsy in 1701 cases and 8078 death certificates were searched. Gall stones were identified as the cause of death in only 21 cases (0.26%) but in 291 subjects found to have gall stones or cholecystectomy at necropsy, the mortality was 3.4%. The necropsy prevalence of gall stones in the adult population was 17.1% but nine out of 10 subjects with gall stones had not had a cholecystectomy and women were three times more likely to have had their gall stones removed than men. There were five postoperative deaths (mean age 60 years) with an operative mortality for cholecystectomy in the district of 1.2%. Death due to unoperated gall stones was identified in 16 subjects, most of whom were very elderly women (mean age 81) but carcinoma of the gall bladder was only found in one woman of 90 with gall stones. The prevalence of gall stones rose with age in both sexes but the cholecystectomy rate per head of population at-risk declined sharply in the seventh decade in women and the eighth decade in men. There are a large number of people with unoperated gall stones in the population but gall stone related deaths are very uncommon. The cholecystectomy rate in Britain, however, seems to be rising and it is suggested that if this trend continues there may be an increased number of deaths