Search results for "ExAC"
showing 10 items of 1440 documents
Risks of Concurrent Execution in E-Commerce Processes
2021
The development of ICT facilitates replacing the traditional buying and selling processes with e-commerce solutions. If several customers are served concurrently, e.g. at the same time, the processes can interference each other causing risks for both the buyer and the seller. The paper offers a method to identify purchase/sale risks in simultaneous multi-customer service processes. First, an exact model of buying-selling processes is created and the conditions for the correct process execution are formulated. Then an analysis of all the possible scenarios, including the concurrently executed buying-selling scenarios, is performed using a symbolic execution of process descriptions. The obtai…
The Kp Hierarchy
1989
As an application of the theory of infinite-dimensional Grassmannians and the representation theory of gl1 we shall study in this chapter certain nonlinear “exactly solvable” systems of differential equations. Exactly solvable means here that the nonlinear system can be transformed to an (infinite-dimensional) linear problem. A prototype of the equations is the Korteweg-de Vries equation $$\frac{{\partial u}}{{\partial t}} = \frac{3}{3}u\frac{{\partial u}}{{\partial x}} + \frac{1}{4}\frac{{{\partial ^3}u}}{{\partial {x^3}}}$$ . It turns out that it is more natural to consider an infinite system of equations like that above, for obtaining explicit solutions. The set of equations is called th…
Mixed Function Oxidase Activity and Organochlorine Levels in Farmed Sharpsnout Seabream (Diplodus puntazzo) from Two Intensive Aquaculture Facilities
2004
Mixed function oxidase (MFO) activities and organochlorine levels were investigated in liver of farmed sharpsnout seabream bred in two intensive facilities, a sea farm and a land-based farm. The aim of this study is to investigate how different facility locations and breeding conditions might affect fish metabolic capabilities and accumulation of toxic chemicals in farmed sharpsnout seabream. The differences between breeding two or more fish species in the same cage or tank known as polyculture, and monoculture (1 species) were also investigated. The results showed that both facility location (sea and land) as well as breeding systems (polyculture and monoculture) might be responsible for t…
Comparison of stable isotope composition and inorganic and organic contaminant levels in wild and farmed bluefin tuna, Thunnus thynnus, in the Medite…
2009
Abstract Stable isotope composition (δ13C and δ15N) and persistent pollutants, including heavy metals (Hg, Cd, Pb, As, Cu, Zn) and organochlorine compounds (PCBs, HCB and p,p′-DDE), were measured in muscle and liver tissues of wild and farmed bluefin tunas to investigate the changes occurring during the farming period and to assess the quality, in terms of contaminants, of the final product. At the end of farming, the food supplied was clearly integrated into the tuna tissues as derived from stable isotope signatures, and, contrarily to the literature findings obtained for other species, farmed tunas showed slight variations in persistent elements and chemical compounds in comparison with w…
The trophic transfer of persistent pollutants (HCB, DDTs, PCBs) within polar marine food webs.
2017
Biomagnification (increase in contaminant concentrations at successively higher levels of trophic web), is a process that can transversally impair biodiversity and human health. Most research shows that biomagnification should be higher at poles with northern sites having a major tendency to biomagnify Persistent Organic Pollutants (POPs) through their marine food webs. We investigated the biomagnification degree into two marine trophic webs combining carbon and nitrogen stable isotopes and POP analyses. We showed that the Antarctic trophic web was more depleted than the sub-Arctic one and the differences highlighted for the basal part could explain the difference in length between them. Co…
HCB, p,p'-DDE and PCB ontogenetic transfer and magnification in bluefin tuna (Thunnus thynnus) from the Mediterranean Sea.
2007
The bluefin tuna, Thunnus thynnus (Linnaeus 1758), is biologically and economically important in the Atlantic--Mediterranean ecosystems. Bluefin tuna feed on diverse food items depending on their age, thus they occupy different trophic levels during their lifespan. Hexachlorobenzene (HCB), p,p'-DDE and polychlorinated biphenyls (PCBs) are well-known persistent organic pollutants (POPs) in the Mediterranean basin. The relationship between stable isotopes of nitrogen (N) and the POP residue levels in tissues has recently increased knowledge on the link between the trophic levels and the contaminant accumulation. Trophic levels were estimated by using 15N/14N ratio (delta15N) and HCB, p,p'-DDE…
Generation of travelling sine-Gordon breathers in noisy long Josephson junctions
2022
The generation of travelling sine-Gordon breathers is achieved through the nonlinear supratransmission effect in a magnetically driven long Josephson junction, in the presence of losses, a current bias, and a thermal noise source. We demonstrate how to exclusively induce breather modes by means of controlled magnetic pulses. A nonmonotonic behavior of the breather-only generation probability is observed as a function of the noise intensity. An experimental protocol providing evidence of the Josephson breather's existence is proposed.
Selection of Series System Components to Maximize Reliability
2010
The paper tackles the problem of maximizing the reliability of a series system by an opportune choice of components. Each type of component must be selected among the available alternatives for that component whereas a fixed amount of budget can not be overcome. The problem can be formulated by a binary non linear programming model and it is equivalent to a knapsack problem with multiple-choice constraints, well known to be NP-hard. An exact algorithm is proposed for solving large dimension problems to the optimum in a short time. The algorithm efficiency is finally compared with the recent heuristics proposed in literature to approach the same problem.
The ziqqurath of exact sequences of n-groupoids
2011
In this work we study exactness in the sesqui-category of n-groupoids. Using homotopy pullbacks, we construct a six term sequence of (n-1)-groupoids from an n-functor between pointed n-groupoids. We show that the sequence is exact in a suitable sense, which generalizes the usual notions of exactness for groups and categorical groups. Moreover, iterating the process, we get a ziqqurath of exact sequences of increasing length and decreasing dimension. For n = 1 we recover a classical result due to R. Brown and, for n = 2 its generalizations due to Hardie, Kamps and Kieboom and to Duskin, Kieboom and Vitale.
Shock formation in the dispersionless Kadomtsev-Petviashvili equation
2016
The dispersionless Kadomtsev-Petviashvili (dKP) equation $(u_t+uu_x)_x=u_{yy}$ is one of the simplest nonlinear wave equations describing two-dimensional shocks. To solve the dKP equation we use a coordinate transformation inspired by the method of characteristics for the one-dimensional Hopf equation $u_t+uu_x=0$. We show numerically that the solutions to the transformed equation do not develop shocks. This permits us to extend the dKP solution as the graph of a multivalued function beyond the critical time when the gradients blow up. This overturned solution is multivalued in a lip shape region in the $(x,y)$ plane, where the solution of the dKP equation exists in a weak sense only, and a…