75,711 research outputs found
The Importance of Open Data in Toxicological Research and Publishing
No full textEvery year thousands of toxicological studies are performed around the World. These studies are most commonly funded by Governmental, Non-Governmental agencies, Universities, Faculties, and in the last 50 years even more so by funds provided by research funding schemes such as the Horizon 2020 and the Framework Programmes in the European Union, or the National Institutes of Health in the United States. As part of these studies, thousands of experiments and field studies are done, collecting millions of tables of data ranging from genotypes and cell-culture reactions to chemical agents, to epidemiological data on populations from different towns and countries. In addition, governmental agencies and private companies measure a vast amount of parameters regarding the environment. Recently, a very specific risk has come to attention of research funders: the results of a specific research project are published in a peer review journal, thus satisfying the basic requirements of the project call, and the raw data which was collected remains buried (or lost) in the hard-disk of participating researchers. To resolve this situation, many institutions have adopted the „Open Data“ policy, which should allow the data collected by these institutions or projects funded by them to be freely available to use and re-use by others. This philosophy was also adopted by many journals which now allow the authors of published articles to store even the raw data in their online repositories. This new trend, which might soon become a rule in the scientific publishing world, considering there are journals specifically designed to store datasets and study protocols, increases the use of already collected data, facilitates data re-use and new discoveries, but also helps authors achieve a higher impact and recognition than by just publishing their work
Environmental Lead Exposure in Children: a Problem of Developing Countries?
No full textEnvironmental exposure to lead, although not an important cause of mortality, represents one of the main causes of morbidity among children and adolescents. In general, rural communities are expected to have significantly lower blood lead levels (BLLs) than urban communities. However, this is not the case in populations living in the vicinity of lead mines and smelting facilities, where higher BLLs may occur, particularly among young children. Around 50% of Global lead production can be traced back to car battery recycling.
The aim of this study was to quantify blood lead levels (BLLs) of children living near a car battery smelting facility in Serbia, compare the levels with developed and developing countries’ standards, and identify the main determinants of lead exposure in this population. BLLs were quantified in 75 children from Zajača, a village where a car battery smelting factory is located, and 52 children from Paskovac, village 5 kilometers away from Zajača. The median BLL for both groups were 12 μg/dl, 7.60 μg/dl in children from Paskovac, and 17.5 μg/dl in children from Zajača. Even 87% of children from Zajača had the BLL above 10 μg/dl, which is comparable to urban schoolchildren in South Africa and Bangladesh. Although a European country, a candidate country for the European Union, BLLs of Serbian children were comparable to that of children living in developing countries and higher than those expected in children living near lead smelting facilities in developed countries
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
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
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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