888 research outputs found

    Dilatation operator and Cayley graphs

    Full text link
    We use the algebraic definition of the Dilatation operator provided by Minahan, Zarembo, Beisert, Kristijansen, Staudacher, proper for single trace products of scalar fields, at leading order in the large-N 't Hooft limit to develop a new approach to the evaluation of the spectrum of the Dilatation operator. We discover a vast number of exact sequences of eigenstates.Comment: 30 pages and 3 eps figures, v2: few typos correcte

    Legal medical consideration of alzheimer’s disease patients’ dysgraphia and cognitive dysfunction: a 6 month follow up

    Get PDF
    Background: The purpose of this study was to investigate the ability of Alzheimer‚Äôs disease (AD) patients to express intentions and desires, and their decision-making capacity. This study examines the findings from a 6-month follow-up of our previous results in which 30 patients participated. Materials and methods: The patient‚Äôs cognition was examined by conducting the tests of 14 questions and letter-writing ability over a period of 19 days, and it was repeated after 6 months. The difference between these two cognitive measures (PQ1 before‚ÄďPQ2 before), tested previously and later the writing test, was designated DőĒ before. The test was repeated after 6 months, and PQ1 after‚ÄďPQ2 after was designated DőĒ after. Results: Several markedly strong relationships between dysgraphia and other measures of cognitive performance in AD patients were observed. The most aged patients (over 86 years), despite less frequency, maintain the cognitive capacity manifested in the graphic expressions. A document, written by an AD patient presents an honest expression of the patient‚Äôs intention if that document is legible, clear, and comprehensive. Conclusion: The identification of impairment/deficits in writing and cognition during different phases of AD may facilitate the understanding of disease progression and identify the occasions during which the patient may be considered sufficiently lucid to make decisions. Keywords: cognition, intentions, unfit to plead, consen

    Pricing agricultural inputs from biodiversity-rich ecosystems and habitats without input markets

    Get PDF
    Purpose: The purpose of this paper is to focus on the analysis of an understudied problem in the economic literature. It proposes a valuation methodology for inputs that come from biodiversity-rich ecosystems/habitats and are used in agro-food production at zero input cost because there is not a market for such inputs. Design/methodology/approach: Following Onofri et al. (2017), the authors computed the value of the marginal productivity of different inputs in three selected case studies (Angola, Mozambique and Brazil). Results are theory based and rigorous but show a strong contingency, case based, relative dimension that is captured, in the framework, by the \u201crelativity ratio.\u201d The ratio expresses the relative weight of the value generated by the input that comes from biodiversity-rich ecosystems/habitats in the per capita monthly available income of the farmer and aims at conveying additional insights to the economic valuation. Findings: In this paper, the assessment of agricultural inputs value (price) in the absence of inputs markets is done, with an application to three different case studies. The inputs are peculiar since they come from habitats and ecosystems that are very biodiversity-rich. Originality/value: The paper proposes a practical, though rigorous, methodology for the assessment of the value (price) of agricultural inputs in absence of inputs markets. Markets do not exist since the inputs come from biodiversity-rich habitats and ecosystems

    Time evolution for quantum systems at finite temperature

    Full text link
    This paper investigates a new formalism to describe real time evolution of quantum systems at finite temperature. A time correlation function among subsystems will be derived which allows for a probabilistic interpretation. Our derivation is non-perturbative and fully quantized. Various numerical methods used to compute the needed path integrals in complex time were tested and their effectiveness was compared. For checking the formalism we used the harmonic oscillator where the numerical results could be compared with exact solutions. Interesting results were also obtained for a system that presents tunneling. A ring of coupled oscillators was treated in order to try to check selfconsistency in the thermodynamic limit. The short time distribution seems to propagate causally in the relativistic case. Our formalism can be extended easily to field theories where it remains to be seen if relevant models will be computable.Comment: uuencoded, 14 pp in Latex, 8 ps Fig

    CFD Ablation Predictions with Coupled GSI Modeling for Charring and non-Charring Materials

    Get PDF
    To this day, a major objective of TPS design is to reduce empiricism, and to increase fundamental modeling capability through increased understanding. One of the most challenging aspect is the proper coupling between the material response and the external flow field. With this regard, the goal of this research activity is the improvement of the numerical modeling capabilities through the development of advanced CFD tools integrated with Gas-Surface Interaction (GSI) modeling. Numerical prediction of ablation is ambitious and cpu-time demanding due to the complex multiphase physical and chemical processes that occur. With improvements in computational algorithms and advances in computer hardware, Navier- Stokes based approaches have become the norm in recent years for coupling to material thermal response predictions. The present state of the art in fluid-material coupling is represented by loose coupling of a high-fidelity CFD flow solver with a material thermal response code. In that respect, some major restrictions are still present in these state of the art coupled solutions: surface chemical equilibrium assumption non-ablating flow field prediction simplified diffusion modeling based on transfer coefficient Chemical equilibrium is a special condition of the general chemical nonequilibrium condition and surface recession rate predicted by the chemical equilibrium surface chemistry is usually reasonably conservative and is considered to be a best alternative when the nonequilibrium computation is too expensive or unlikely to be achieved. The ablation models are currently largely based on the surface equilibrium assumption and the effects and importance of non-equilibrium ablation models coupled with CFD tools are only beginning to be explored. Moreover, the coupling between CFD solver and material response code is often made considering non-ablating flow field solutions assuming a fully/super-catalytic, radiative equilibrium wall. This means that the effect on the flow field solution of the ablation and pyrolysis gas injection and of variable surface temperature are treated only approximately relying on the use of mass and energy transfer coefficients and semi-empirical blowing correction equations. Finally, the ablation rate is generally computed by the material response code using thermochemical tables and extremely simplified diffusion models based on transfer coefficients and semi-empirical relations relating mass and energy transfer. The objective of this research activity is to remove these major limiting assumptions developing suitable finite-rate GSI models and integrating CFD technology with Computational Surface Thermochemistry (CST) to take into account the effect of surface ablation and pyrolysis gas injection on the flow field and to allow surface ablation and surface temperature distributions to be determined as part of the CFD solution. Because the entire flow field is to be solved with ablative boundary conditions, the film-transfer theory assumption is no longer needed; this will permit to avoid all of the classical approximations such as transfer coefficients, equilibrium thermochemical tables, and blowing correction equations which needs to be used when ablative boundary conditions are not accounted for in the CFD solution. The ablative boundary conditions, based on finite-rate chemistry, species mass conservation and surface energy balance, is discretized and integrated with the CFD code to predict aerothermal heating, surface temperature, gas-phase surface composition, and surface ablation rate. The concentrations of chemical species at wall are determined from finite-rate gas-surface chemical reactions balanced by mass transfer rate. The surface temperature is determined from the surface energy balance assuming steady-state ablation or coupling with a thermal response code. The surface recession rate and the surface temperature are thus obtained as part of the flow field solution. The computational tool developed in this work is used to simulate two sets of experimental data for nozzle material ablation: sub-scale motor tests carried out for the Space Shuttle Reusable Solid Rocket Motor and the static firing tests of the second and third stage solid rocket motors of the European VEGA launcher which use carbon-carbon for the throat insert and carbon-phenolic for the region downstream of the throat

    CAUSTIQUES EN CHAMP PROCHE GENEREES PAR DES PARTICULES TRANSPARENTES RECONSTRUCTION PAR HOLOGRAPHIE NUMERIQUE EN LIGNE

    Get PDF
    International audienceL'holographie numerique en ligne est une technique d'imagerie volumetrique particulierement adaptee a la caracterisation spatiale (position, vitesse et tailles/morphologies) des ecoulements particulaires dilues. Dans de nombreux domaines la connaissance de la composition des particules est aussi d'un grand interet. Nous realisons cette mesure avec l'holographie numerique en ligne par l'analyse du champ proche des particules. Dans cette region les contributions des differents processus de diffusion de la lumiere peuvent etre plus facilement distinguees et notamment les caracteristiques du jet photonique (caustique vers l'avant generee par les rayons simplement refractes). La localisation dans l'espace du maximum d'intensite de cette caustique permet d'estimer l'indice de refraction relatif des particules. Dans cette communication, nous montrons que, dans le cadre de l'approximation de Fresnel de la diffraction scalaire, le jet photonique reconstruit par holographie numerique correspond a la tache d'Airy d'une lentille spherique. Par analogie avec les notions d'images virtuelles et reelles employees en optique pour les lentilles convergentes et divergentes, cette tache est restituee de facon reelle pour les particules ayant un indice relatif superieur a un et de facon virtuelle pour les particules dont l'indice relatif est plus petit que l'unite. Ceci fournit une solution simple et numeriquement tres efficace pour differencier ou caracteriser la composition des particules solides, liquides ou gazeuses. Une validation experimentale en laboratoire sur un ecoulement triphasique montre qu'il est desormais possible d'obtenir simultanement la position dans l'espace, la vitesse, la trajectoire, la taille et la composition de particules en ecoulement

    Holocenska sedimentacija u solinskom kanalu (Mljetska jezera, Jadransko more)

    Get PDF
    A 103 cm long core from the Soline Channel (Mljet Island, Adriatic Sea), which is at present a surface connection between the peculiar marine Mljet Lakes and the open sea, indicates substantial changes of the sedimentary environment in the Holocene. In the layer dated to 4,600 B.P., 25‚Äď30 cm below the bottom (which is at 2.8 m depth), freshwater algae represented by species of Chara/Nitella were found along with the gastropod Limnea stagnalis. This dominantly brackish sediment extends from 10 to 60 cm below the bottom. Above that interval marine sediment was found and below it quartz dominated the subareal or freshwater sediment. This indicates that the surface marine connection between Mljet Lakes and the sea was established after deposition of freshwater/brackish sediments i.e. not earlier than ca. 4 kyr B.P.Jezgra dugańćka 103 cm izvańĎena iz kanala Soline (otok Mljet, Jadransko more), koji je danas povrŇ°inska veza izmeńĎu jedinstvenih morskih Mljetskih jezera i otvorenog mora, ukazuje na bitne promijene taloŇĺnog okoliŇ°a u holocenu. U sloju ńćija je starost procijenjena na 4,600 godina, 25‚Äď30 cm ispod dna (koje se nalazi na dubini od 2.8 m), nańĎene su slatkovodne alge iz roda Chara/Nitella zajedno s puŇĺevima Limmnea stagnalis. Ti preteŇĺno bońćati sedimenti proteŇĺu se od 10 do 60 cm ispod dna. Iznad njih nalaze se marinski sedimenti a ispod kopneni ili slatkovodni sedimenti. To ukazuje da je povrŇ°inska veza morem izmeńĎu Mljetskih jezera i otvorenog mora uspostavljena nakon taloŇĺenja slatkovodnih/bońćatih sedimenata tj. ne prije oko 4 tisuńáe godina

    Developments and new applications of numerical stochastic perturbation theory

    Get PDF
    A review of new developments in numerical stochastic perturbation theory (NSPT) is presented. In particular, the status of the extension of the method to gauge fixed lattice QCD is reviewed and a first application to compact (scalar) QED is presented. Lacking still a general proof of the convergence of the underlying stochastic processes, a self-consistent method for testing the results is discussed.Comment: 3 pages, 1 figure. Poster presented at the Lattice97 conference, Edinburgh, U

    REVIEW OF THE EXPERIMENTAL SETTING OF POLYETHYLENE BAGS - COLLECTORS FOR COLLECTING THE SHELLFISH LARVAE

    Get PDF
    U radu se opisuju i analiziraju dosadaŇ°nja istraŇĺivanja u vezi s eksperimentalnim postavljanjem polietilenskih vreńáa kao kolektora za prikupljanje mlańĎi Ň°koljkaŇ°a. Ukratko se opisuju osnove tehnologije uzgoja Ň°koljkaŇ°a te se iscrpnije obrańĎuju literaturni podatci u vezi s mjestom, sezonom i nańćinom postavljanja eksperimentalnih kolektora. Rezultati dosadaŇ°njih istraŇĺivanja mogu se iskoristiti kao odrednice, a za razvoj komercijalnog uzgoja Ň°koljkaŇ°a na svakom se novom lokalitetu preporuńćuje eksperimentalno postavljanje kolektora.This work describes and analyses former researches regarding the experi mental setting of polyethylene bags as collectors for collecting the shellfish fry. Basic shellfish cultivation technologies are being briefly described and the literature data regarding the place, season and way of setting the experimental collectors are being detailed. The results of the former researches can be used as references while for the development of the commercial shellfish cultivation on each new location the experimental collec tor setting is recommended

    REVIEW OF THE EXPERIMENTAL SETTING OF POLYETHYLENE BAGS - COLLECTORS FOR COLLECTING THE SHELLFISH LARVAE

    Get PDF
    U radu se opisuju i analiziraju dosadaŇ°nja istraŇĺivanja u vezi s eksperimentalnim postavljanjem polietilenskih vreńáa kao kolektora za prikupljanje mlańĎi Ň°koljkaŇ°a. Ukratko se opisuju osnove tehnologije uzgoja Ň°koljkaŇ°a te se iscrpnije obrańĎuju literaturni podatci u vezi s mjestom, sezonom i nańćinom postavljanja eksperimentalnih kolektora. Rezultati dosadaŇ°njih istraŇĺivanja mogu se iskoristiti kao odrednice, a za razvoj komercijalnog uzgoja Ň°koljkaŇ°a na svakom se novom lokalitetu preporuńćuje eksperimentalno postavljanje kolektora.This work describes and analyses former researches regarding the experi mental setting of polyethylene bags as collectors for collecting the shellfish fry. Basic shellfish cultivation technologies are being briefly described and the literature data regarding the place, season and way of setting the experimental collectors are being detailed. The results of the former researches can be used as references while for the development of the commercial shellfish cultivation on each new location the experimental collec tor setting is recommended
    • ‚Ķ
    corecore