74,962 research outputs found
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Final word on Jersey Dutch
No full textIn this article, William Z. Shetter compares and contrasts the dialects that developed between different Dutch colonies in the New World. He explores in-depth the nuances of Jersey Dutch, and provides theories to explain how Dutch and colonial languages blended. The article is reprinted from American Speech, December 1958, Volum XXXIII, No. 4
Occupational health risk of working in garages: comparative study on blood pressure and hematological parameters between garage workers and Haramaya University community, Harar, eastern Ethiopia
No full textZerihun Ataro,1 Abraham Geremew,2 Fekadu Urgessa3 1Department of Medical Laboratory Sciences, 2Department of Environmental Health Sciences, College of Health and Medical Sciences, Haramaya University, Harar, Ethiopia, 3School of Medical Laboratory Science, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia Background: Occupational exposure to chemicals in garages causes a wide range of biological effects, depending upon the level and duration of exposure. In Ethiopia, there have been few studies conducted to assess the exposure of garage workers to chemicals. Preceding studies have not explored the effect of working in garage on blood pressure and hematological parameters. Therefore, this study aimed to assess differences in blood pressure and hematological parameters among garage workers compared to the Haramaya University community, Harar, eastern Ethiopia.Materials and methods: A comparative cross-sectional study was conducted in Harar town, eastern Ethiopia. Thirty garage workers were selected and compared with 30 age- and sex-matched controls comprising of teachers and students. Demographic and occupational data were collected by using a structured questionnaire by a trained data collector. Blood pressure was measured using sphygmomanometry. Hematological parameters were measured with an automated hematology analyzer. Data were analyzed using Stata version 13.Results: The majority of the garage workers did not implement effective preventive or control measures for workplace chemical exposure. Statistically significant increases were found in systolic (128.67±18.14 vs 106.33 ±9.27 mmHg, P<0.0001), diastolic blood pressure (90.33±11.29 vs 75.67 ±5.68 mmHg, P<0.0001), total white blood cells (7.9±1.51 vs 6.72±2.04×109 cells/L, P=0.0138), and platelets (323.20±48.82 vs 244.1±47.3×109 cells/L, P<0.0001) in garage workers compared to the control group. On the other hand, statistically significant decreases were found in red blood cells (5.13±0.38 vs 5.46±0.36×1012 cells/L, P=0.0006), hemoglobin (14.89±0.71 vs 15.45±0.87 g/dL, P=0.0062), hematocrit (43.98%±1.99% vs 46.4%3±2.32%, P<0.0001), and mean corpuscular volume (83.19±2.93 vs 85.11±3.87 fL, P=0.0353) among garage workers compared to the control group.Conclusion: There were significant differences in blood pressure and hematological parameters between garage workers and the control group. Therefore, appropriate and effective safety measures need to be taken by the workers to prevent possible chemical exposure during routine tasks. Keywords: garage workers, blood pressure, hematological parameters, Harar, Ethiopi
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Magnitude and associated factors of diabetes mellitus and hypertension among adult HIV-positive individuals receiving highly active antiretroviral therapy at Jugal Hospital, Harar, Ethiopia
No full textZerihun Ataro,1 Wondimye Ashenafi,2 Jiregna Fayera,3 Tekabe Abdosh3 1Department of Medical Laboratory Sciences, College of Health and Medical Sciences, Haramaya University, Harar, Ethiopia; 2School of Public Health, College of Health and Medical Sciences, Haramaya University, Harar, Ethiopia; 3School of Medicine, College of Health Sciences, Haramaya University, Harar, Ethiopia Background: People with HIV infection are at increased risk of noncommunicable diseases (NCDs). Diabetes mellitus (DM) and hypertension are recognized as the major NCDs. Except few findings in general population, there is no well-documented evidence on the magnitude of NCDs and associated factors among HIV-positive patients. Purpose: The aim of this study was to determine the magnitude and associated factors of DM and hypertension among adult HIV-positive subjects receiving highly active antiretroviral therapy (HAART) Methods: A hospital-based cross-sectional study was conducted from February to April at Jugal Hospital, Harar, Eastern Ethiopia. Sociodemographic and anthropometric data and blood pressure (BP) were collected by senior clinical nurses. A total of 5 mL of venous blood was collected. Serum glucose and lipid profile were measured using the Autolab 18 clinical chemistry analyzer. Data were analyzed using STATA version 13. Results: A total of 425 HIV-infected individuals taking HAART of age ranging from 18 to 68 years were included. The prevalence of DM and hypertension were 7.1% (95% CI: 4.9–9.9) and 12.7% (95% CI: 9.8–16.2), respectively. Increased blood triglyceride (adjusted odds ratio [AOR] =4.7, 95% CI: 1.7–13.1), high BP (AOR =3.3, 95% CI: 1.1–9.5), and high baseline body mass index (BMI) (AOR =8.7, 95% CI: 2.4–31.8) were significantly associated with DM. In contrast, raised waist–hip ratio (AOR =4.6, 95% CI: 1.6–13.3), raised blood glucose (AOR =3.5, 95% CI: 1.1–11.4), increased total cholesterol (AOR =3.9, 95% CI: 1.3–11.9), high current BMI (AOR =3.8, 95% CI: 1.5–9.6), drinking alcohol (AOR =3.4, 95% CI: 1.5–8.1), CD4 count <500 cell/mL (AOR =2.7, 95% CI: 1.3–5.6), and longer duration of HAART (AOR =2.3, 95% CI: 1.1–5.1) were significantly associated with hypertension. Conclusion: DM and hypertension were frequent among HIV patients on HAART, and they were linked to the well-known risk factors. Therefore, regular screening and monitoring of DM and hypertension before and after the initiation of HAART is of paramount importance. Keywords: diabetes mellitus, hypertension, HIV, HAART, Ethiopi
Statistics of the subgrid scales after the shock-turbulence interaction
No full textThe interaction of a normal shock with isotropic turbulence (IT) represents a basic problem for studying some of the phenomena associated with high speed flows, such as hypersonic flight, supersonic combustion and Inertial Confinement Fusion (ICF). In general, in practical applications, the shock width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J. Fluid Mech., 756, R1, 2014) show that the interaction can be described by the Linear Interaction Approximation (LIA). By using LIA to alleviate the need to solve the shock, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number around are used to investigate the properties of the subgrid scales (SGS). In particular, it is shown that the shock interaction decreases the asymmetry of the SGS dissipation PDF as the shock Mach number increases, with a significant enhancement in size of the regions and magnitude of backscatter
Transition to turbulence in a qblique shock-wave/boundary-layer interaction at M=15
No full textDirect numerical simulations are carried out for different forcing techniques to trigger transition during the interaction between an oblique shock-wave and a laminar boundary-layer at M = 1.5. Three forcing methods are used: a) forcing of oblique unstable modes, whose shape and behaviour are determined by the local linear stability theory, b) broadband free-stream acoustic disturbances, and c) a cold plasma flow control device. While the oblique-mode breakdown is dominant for low-amplitude forcing, long streaky structures drive the transition process in a high-amplitude disturbance environment. LES are also performed on the experimental setup by the Institute of Theoretical and Applied Mechanics (ITAM) from Novosibirsk State University with cold plasma actuation. As well as the disturbance type, the effect of Reynolds number and forcing amplitude will be investigated
Triangular Constellations in Flows
No full textParticles advected on the surface of a fluid can exhibit fractal clustering. The local structure of a fractal set is described by its dimension , which is the exponent of a power-law relating the mass in a ball to its radius : . It is desirable to characterise the {\em shapes} of constellations of points sampling a fractal measure, as well as their masses. The simplest example is the distribution of shapes of triangles formed by triplets of points, which we investigate for fractals generated by chaotic dynamical systems. The most significant parameter describing the triangle shape is the ratio of its area to the radius of gyration squared. We show that the probability density of has a phase transition: is independent of and approximately uniform below a critical flow compressibility , which we estimate. For the distribution appears to be described by two power laws: when , and when
Preferential concentration of particles in compressible turbulence
No full textThe behavior of particles in compressible turbulence has been seldom investigated to date despite its importance in many natural and industrial flows. Direct numerical simulations of particle-laden compressible isotropic turbulence are performed to study the preferential concentration of particles and the underling mechanisms. It turns out that heavy particles tend to concentrate in regions of low enstrophy and high fluid density (i.e, strain regions between vortex rings), especially the particles of Kolmogorov scale, which show the largest number density. Due to the compressibility, fluid particles do not distribute uniformly as in incompressible case, but show a tendency to bunch up in high density zones. The preliminary result might give some insights into compressible turbulent transport, dispersion and mixing as well as the subgrid-scale modeling for large-eddy simulation of particle-laden compressible flows
Turbulent structures in unsteady wall-bounded flow subject to temporal acceleration
No full textDirect numerical simulations (DNS) of a transient turbulent channel flow subject to constant temporal acceleration have been performed with a final Reynolds number of \Retau=800. The response of turbulent structures to the temporal acceleration is investigated. A significant delay in the response of turbulent flow is observed in various turbulent properties. It is found that the response of turbulent flow to temporal acceleration consists of two stages: the destruction of the initial \emph{old} turbulence, followed by the generation of \emph{new} turbulence associated with a higher number. The \emph{new} turbulence is much stronger than the \emph{old} turbulence
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