75,047 research outputs found
Growth of galliumnitride on sapphire and silicon using propylamine as nitrogen precursor
No full textAtakan B, Liu Z-J. Growth of galliumnitride on sapphire and silicon using propylamine as nitrogen precursor. JOURNAL DE PHYSIQUE IV. 2001;11(PR3):525-530
Cannabis abuse and vulnerability to psychosis: Targeting preventive services
No full textCannabis is the most widely used illicit substance in the world and due to the high levels of use observed among young people with psychosis, most research has focused on the causal relationship between cannabis use and mental health problems. Despite a large interest in developing intervention models to target this group, there are as yet no established and effective methods of prevention and intervention focusing on cannabis use. In this paper we present the available evidence for the effectiveness of substance use treatments in patients with co-morbid severe mental illness, as well as exploring the prevention and early intervention initiatives for substance use in the general population. © 2012 Bentham Science Publishers
Deposition of hexagonal GaN using n-propylamine as a nitrogen precursor
No full textLiu Z-J, Atakan B, Kohse-Höinghaus K. Deposition of hexagonal GaN using n-propylamine as a nitrogen precursor. JOURNAL OF CRYSTAL GROWTH. 2000;219(1-2):176-179.A new gaseous mixture containing n-propylamine, trimethylgallium (TMG) and ammonia was used to deposit gallium nitride films. Pure and transparent, polycrystalline films were obtained and analysed by scanning electron microscopy (SEM) and Raman spectroscopy. n-Propylamine has an important influence on the crystal structure of the resulting gallium nitride deposits, and the presence of n-propylamine in the reaction system thus provides a new solution for deposition of high-quality gallium nitride films. (C) 2000 Elsevier Science B.V. All rights reserved
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
Is cannabis neurotoxic for the healthy brain? A meta-analytical review of structural brain alterations in non-psychotic users
No full textDespite growing research in the field of cannabis imaging, mostly in those with a psychotic illness, the possible neurotoxic effects of smoked cannabis on the healthy brain have yet to be fully understood. There appears to be a need to evaluate the existing imaging data on the neuroanatomical effects of cannabis use on non-psychotic population
Ekstrakcja miedzi z żużlu z zakładów recyklingu za pomocą wzbogacalnika Falcon
No full textThis investigation is concerned with the extraction of nugget copper particles from copper recovery plant slag which recycled of copper scrap. For this purpose, the Falcon concentrator was used because of its enhanced gravity properties. The Falcon concentrator has a fast spinning bowl which creates a centrifugal force to separate fine size minerals on the basis of their density differences. In the tests, the tailings of the copper recovery plant were used and the test sample was divided into two groups and one of them was classified in narrow particle sizes. The operational parameters were determined as particle size, centrifugal force and washing water pressures. The water pressure and centrifugal force have an inversely proportional relationship. Because of this phenomenon, the G/P parameter was created. The test conditions were applied to the whole distribution sample and narrow size distribution samples in the same way. The test results indicate that the average grade was elevated from 1.04% to 6.50% with the recovery of 15.07% and 619% enrichment ratio for narrow sizes, whereas grade was elevated to 4.36% with 13.24% recovery and 415.94% enrichment ratio for the whole distribution. As a result, the recovery and grade values of concentrates are not good enough for gravity concentration process for both samples. However, this process was applied to the double recycled material and the lower recovery, grade values can be tolerated because of concentrate is nugget copper metal. The concentrate can also be washed in cleaning table for increasing the grade value for adding to initial feed of plant. This process can, therefore, supply important earnings not only economically but also environmentally.Badanie dotyczy ekstrakcji rodzimych cząstek miedzi z żużlu z zakładów recyklingu. W tym celu zastosowano wzbogacalnik Falcon ze względu na jego zwiększone właściwości wzbogacania grawitacyjnego. Wzbogacalnik Falcon ma szybko obracającą się misę, w której wytwarzana siła odśrodkowa powoduje rozdział minerałów o niewielkich wymiarach cząstek w zależności od ich różnych gęstości. W testach wykorzystano odpady z instalacji odzysku miedzi, a próbkę podzielono na dwie grupy, jedną z nich zaklasyfikowano do klasy cząstek o niewielkich wymiarach. Parametry technologiczne zostały określone i są to: wielkość cząstek, siła odśrodkowa i ciśnienia wody płukającej. Ciśnienie wody (P) i siła odśrodkowa grawitacji (G) charakteryzują się zależnością odwrotnie proporcjonalną. Z powodu tego zjawiska został utworzony parametr G/P. Zastosowano takie same warunki testu do rozdzielonych próbek o niewielkich wymiarach cząstek. Wyniki wskazują, że średnia ocena została podwyższona z 1,04 do 6,50% przy odzysku 15,07% i stopniu wzbogacania 619%. Dla cząstek niewielkich wymiarów ocena została podniesiona do 4,36% przy odzysku 13,24% i stopniu wzbogacania 415,94% dla całej dystrybucji. W rezultacie odzyski i wartości stopni wzbogacania koncentratów nie są wystarczająco dobre dla procesu wzbogacania grawitacyjnego dla obu próbek. Jednak proces ten został zastosowany do materiału z podwójnego recyklingu, a niższy poziom odzysku i stopnie wzbogacania mogą być akceptowane, ponieważ koncentrat stanowi rodzima miedź. Koncentrat może być również wzbogacany na stole koncentracyjnym w celu zwiększenia wartości stopnia wzbogacania do dodania do nadawy na zakład przeróbczy. W ten sposób proces ten może przynieść istotne zyski nie tylko w wymiarze ekonomicznym, ale także środowiskowym
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
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