498 research outputs found
A Comparison of Some Methods of Deriving the Instantaneous Unit Hydrograph
The geomorphological instantaneous unit hydrograph (IUH) proposed by Gupta et al. (1980) was compared with the IUH derived by commonly used time-area and Nash methods. This comparison was performed by analyzing the effective rainfall-direct runoff relationship for four large basins in Central Italy ranging in area from 934 to 4,147 km2.
The Nash method was found to be the most accurate of the three methods. The geomorphological method, with only one parameter estimated in advance from the observed data, was found to be little less accurate than the Nash method which has two parameters determined from observations. Furthermore, if the geomorphological and Nash methods employed the same information represented by basin lag, then they produced similar accuracy provided the other Nash parameter, expressed by the product of peak flow and time to peak, was empirically assessed within a wide range of values. It was concluded that it was more appropriate to use the geomorphological method for ungaged basins and the Nash method for gaged basins
Dynamic Behaviour of the Patented Kobold Tidal Current Turbine: Numerical and Experimental Aspects
This paper provides a summary of the work done at DPA on numerical and experimental investigations of a novel patented vertical axis and variable pitching blades hydro turbine designed to harness energy from marine tidal currents. Ponte di Archimede S.p.A. Company, located in Messina, Italy, owns the patented KOBOLD turbine that is moored in the Messina Strait, between the mainland and Sicily. The turbine has a rotor with a diameter of 6 meters, three vertical blades of 5 meters span with a 0.4 m chord ad hoc designed curved airfoil, producing high lift with no cavitation. The rated power is 160 kW with 3.5 m/s current speed, which means 25% global system efficiency. The VAWT and VAWT_DYN computer codes, based on Double Multiple Steamtube, have been developed to predict the steady and dynamic performances of a cycloturbine with fixed or self-acting variable pitch straight-blades. A theoretical analysis and a numerical prediction of the turbine performances as well as experimental test results on both a model and the real scale turbine will be presented and discussed.
DAMA: the global distribution of alien mammals database
We developed the DAMA (Distribution of Alien MAmmals) database, a comprehensive source reporting the global distribution of the 230 species of mammals that have established, self-sustaining and free-ranging populations outside their native range due to direct or indirect human action. Every alien range is accompanied by information on its invasion stage, pathway, method of introduction and date of introduction. We collected information from 827 different sources (scientific literature, books, risk assessments, reports, online biodiversity databases and websites), and used it to draw alien range maps for these species following the IUCN mapping framework. DAMA comprises 2726 range polygons, covering 199 Countries, 2190 level 1 administrative areas and 11 zoogeographic realms for the period 21500 BC-AD 2017. The most represented orders among introduced mammal species are Rodentia (n=58, 25.22%), Cetartiodactyla (n=49 species, 21.30%), Carnivora (n=30 species, 13.04%), Diprotodontia (n=28, 12.17%) and Primates (n=26, 11.30%). Mammal species have been frequently introduced for hunting (n=100), pet trade (n=57), conservation (n=51) and fauna improvement (n=42). The majority of range polygons are placed on islands (n=2196, 80.56%), encompass populations that have moved beyond establishment and into the invasion stage (n=1655, 60.71%), and originated from 1500 AD to the present (n=1496, 54.88%). Despite inheriting literature biases towards more studied regions (e.g., developed Countries), DAMA is the most up-to-date picture of alien mammal global distribution and can be used to investigate their invasion ecology across different biogeographical regions. There are no copyright or proprietary restrictions; IUCN range maps were modified into a derivative work according to the IUCN's terms of service
tBid induces alterations of mitochondrial fatty acid oxidation flux by malonyl-CoA-independent inhibition of carnitine palmitoyltransferase-1.
Recent studies suggest a close relationship between cell metabolism and apoptosis. We have evaluated changes in lipid metabolism on permeabilized hepatocytes treated with truncated Bid (tBid) in the presence of caspase inhibitors and exogenous cytochrome c. The measurement of b-oxidation flux by labeled palmitate demonstrates that tBid inhibits b-oxidation, thereby resulting in the accumulation of palmitoyl-coenzyme A (CoA) and depletion of acetyl-carnitine and acylcarnitines, which is pathognomonic for inhibition of carnitine palmitoyltransferase-1 (CPT-1). We also show that tBid decreases CPT-1 activity by a mechanism independent of both malonyl-CoA, the key inhibitory molecule of CPT-1, and Bak and/or Bax, but
dependent on cardiolipin decrease. Overexpression of Bcl-2, which is able to interact with CPT-1, counteracts the effects exerted by tBid on b-oxidation. The unexpected role of tBid in the regulation of lipid b-oxidation suggests a model in which tBid-induced metabolic decline leads to the accumulation of toxic lipid metabolites such as palmitoyl-CoA, which might become participants in the apoptotic pathway
tvorba vektorskih mezona i pridružene stranosti pomoću snopa linearno polariziranih fotona u JLabu
The set of experiments forming the g8a run took place in the summer of 2001 in Hall B of Jefferson Lab. The g8a run was the commissioning experiment for the linearly polarised photon beam at CLAS. The aim of these experiments is to improve the understanding of the underlying symmetry of the quark degrees of freedom in the nucleon, the nature of the parity exchange between the incident photon and the target nucleon, and the mechanism of associated strangeness production in electromagnetic reactions. A beam of tagged and collimated linearly polarised photons (energy range 1.8−2.2 GeV) in conjunction with the large solid angle coverage of CLAS make possible the extraction of the differential cross-sections and polarisation observables for the photoproduction of vector mesons and kaons. The reaction channels −→γ p → ρ 0p → π +π −p and −→γ p → K+Λ 0 → K+π −p are under investigation to search for possibly missing nucleon resonances. An overview of the experiment and preliminary results on the measurement of the photon asymmetries of the aforementioned reactions are presented.Mjerenje g8a izveli smo u ljeto 2001 u Halli B u JLabu. To je mjerenje ujedno bilo puštanje u pogon linearno polariziranog snopa kod uređaja CLAS. Cilj tih mjerenja bio je unapređenje našeg shvaćanja simetrije koja je osnova kvarkovskih stupnjeva slobode u nukleonu, značajki izmjene parnosti između fotona i nukleona u meti i mehanizma tvorbe pridružene stranosti u elektromagnetskim reakcijama. Snop kolimiranih i označenih linearno polariziranih fotona (energije 1.8 − 2.2 GeV), zajedno s velikim prostornim kutom CLASa, omogućili su određivanje diferencijalnih udarnih presjeka i polarizacijskih veličina za fototvorbu vektorskih mezona i kaona. Istraživali smo reakcijske kanale →γ p → ρ 0p → π +π −p i →γ p → K+Λ 0 → K+π −p radi mogućeg nalaženja novih nukleonskih rezonancija. Dajemo opis mjerenja i prethodne ishode za fotonsku asimetriju navedenih reakcija
A Novel Manufacturing Technology for RF MEMS Devices on Ceramic Substrates
Microelectromechanical systems are often used for their enormous capability and good qualities in T/R modules especially for space modular applications. High isolation and very low insertion loss are guaranteed by their intrinsic working principle. This is a very robust, flexible, and low-cost technology, and it provides high reliability, good reproducibility, and complete fulfillment of technical requirements
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