176 research outputs found

    On the Recent Debate on Capital Theory and General Equilibrium

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    The paper disputes the negative conclusion of prof. Mandler on the thesis by Garegnani, Schefold, Parrinello that intertemporal general equilibrium theory too is undermined by reswitching and reverse capital deepening. The paper argues that Mandler’s conclusion rests upon highly criticisable assumptions that render the equations of intertemporal general equilibrium identical to those of general equilibria without capital goods. The Walrasian treatment of the capital endowment is criticized in Part I on the basis of its insufficient persistence, and of other ‘methodological’ criticisms that are systematically surveyed. In Part II it is shown through a numerical example that Mandler’s claim, that the assumption of a single consumer guarantees uniqueness of intertemporal equilibrium independently of reswitching or reverse capital deepening, rests on the absence of production of capital goods in the last period of the equilibrium; this assumption is thus revealed to be one of the tricks that prevents the existence of capital goods from changing the properties of the equilibrium relative to those of equilibria without capital

    A Comment On Gintis's "The Dynamics of General Equilibrium"

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    Gintis (2007, 'The Dynamics of General Equilibrium'', Economic Journal 117 (523) , 1280–1309) provides an agent-based model of a Walrasian economy where the tñtonnement is replaced by imitation. His simulations show that the economy converges to the Walrasian equilibrium. Gintis concludes that 1) his stability results provide some justification for the importance placed upon the Walrasian model, and 2) models allowing agents to imitate successful others lead to an economy with a reasonable level of stability and efficiency. Since these conclusions appear to be intended as general, we caution that Gintis''s findings can only be accepted for Walrasian models without capital goods in models with capital goods imitation-based adjustments alter the equilibrium''s data (which makes the demonstration of stability impossible) and raise other important problems (absent from Gintis''s simulations) still awaiting exploration.

    Entropy-based random models for hypergraphs

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    Network science has traditionally focused on pairwise relationships while disregarding many-body interactions. Hypergraphs are promising mathematical objects for the description of the latter ones. Here, we propose null models to analyse hypergraphs that generalise the classical Erdös-Rényi and Configuration Model by randomising incidence matrices in a constrained fashion. After discussing them, we extend the definition of several network quantities to hypergraphs, derive their expected values and compare them with empirical ones, to detect significant deviations from random behaviours

    Automated image analysis method for oil-release test of lipid-based materials

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    We present an automated method to determine oil release from lipid-based materials. Oil-release tests can provide information regarding the ability to retain oil within the structuring network of lipid-based materials. This test provides a first insight into the stability of these materials and their possible applications in food, cosmetic, and pharmaceutical products. The method presented features a simple setup comprising a camera that automatically captures images of the evolution of the oil stain released from lipid-based materials placed on a filter paper. Image postprocessing is performed with two custom-made scripts developed for the freeware application ImageJ. The scripts allow direct calculation of the oil-stain area from all images stored in a folder returning as output numerical values in a table. This method was shown to be: inexpensive, as the employed tools and equipment are available in most laboratories both in academia and industry, self-running, as the method automatically captures images at predefined time intervals for a certain time span, practical, as manual-image analysis is unnecessary (200 images can be automatically analyzed in 3 min). (C) 2021 Published by Elsevier B.V.Peer reviewe

    Ultrasonic-Standing-Wave-Crystallized Oleogels Characterized via Oscillatory Rheology

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    Ultrasonic standing waves, have been shown by our research group, to change the mechanical properties of crystallizing monoglyceride oleogels, which are viscoelastic lipid-based materials featuring a 3D network of structuring molecules. Oleogels are a potentially healthier alternative to traditional fats, such as butter, margarine, and shortenings. Here, we continue our research on ultrasonic-standing-wave-treated oleogels by investigating their mechanical properties through linear and non-linear oscillatory shear rheology. We found that the mechanical response of the treated oleogels is more elastic at lower strains and more viscous at higher strains when compared to reference samples, while the overall shape of the response curves remains similar. Through characterization of ultrasound-standing-wave-treated oleogels, we expand the previous knowledge of the state-of-the-art lipid-based materials.Peer reviewe

    Turbulence and magnetic spots at the surface of hot massive stars

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    4 pages, 1 figure, to appear in the proceedings of IAU Symposium 273 "Physics of Sun and Starspots"Hot luminous stars show a variety of phenomena in their photospheres and in their winds which still lack clear physical explanations at this time. Among these phenomena are non-thermal line broadening, line profile variability (LPVs), discrete absorption components (DACs), wind clumping and stochastically excited pulsations. Cantiello et al. (2009) argued that a convection zone close to the surface of hot, massive stars, could be responsible for some of these phenomena. This convective zone is caused by a peak in the opacity due to iron recombination and for this reason is referred as the "iron convection zone" (FeCZ). 3D MHD simulations are used to explore the possible effects of such subsurface convection on the surface properties of hot, massive stars. We argue that turbulence and localized magnetic spots at the surface are the likely consequence of subsurface convection in early type stars.Peer reviewe

    3D MHD simulations of subsurface convection in OB stars

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    To appear in the proceedings of the IAU272 "Active OB stars: structure, evolution, mass loss and critical limits" Volume: 6 Host publication title: Active OB stars: structure, evolution, mass loss and critical limitsDuring their main sequence evolution, massive stars can develop convective regions very close to their surface. These regions are caused by an opacity peak associated with iron ionization. Cantiello et al. (2009) found a possible connection between the presence of sub-photospheric convective motions and small scale stochastic velocities in the photosphere of early-type stars. This supports a physical mechanism where microturbulence is caused by waves that are triggered by subsurface convection zones. They further suggest that clumping in the inner parts of the winds of OB stars could be related to subsurface convection, and that the convective layers may also be responsible for stochastic excitation of non-radial pulsations. Furthermore, magnetic fields produced in the iron convection zone could appear at the surface of such massive stars. Therefore subsurface convection could be responsible for the occurrence of observable phenomena such as line profile variability and discrete absorption components. These phenomena have been observed for decades, but still evade a clear theoretical explanation. Here we present preliminary results from 3D MHD simulations of such subsurface convection.Non peer reviewe

    Spruce galactoglucomannan-stabilized emulsions as essential fatty acid delivery systems for functionalized drinkable yogurt and oat-based beverage

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    The food industry has a considerable demand for functional foods, such as emulsions as delivery system for omega-6 and omega-3 fatty acids. Such delivery systems must be stabilized, ideally with a compound that fulfills the criteria for both functionality and sustainability. Spruce galactoglucomannans (GGM) are novel, wood-derived, natural, value-added, versatile, multi-purpose emulsifiers that can physically stabilize oil-in-water emulsions while simultaneously protecting the oil phase against oxidation. In this study, we present for the first time the use of GGM-stabilized emulsions as complex multicomponent delivery systems for omega-6 and omega-3 fatty acids, i.e., (1) cod liver oil in drinkable yogurt and (2) oat oil in a gluten-free vegan beverage. The emulsions and the resulting functionalized beverages were characterized in terms of their physical stabilities. In addition, functionalized, drinkable yogurt was characterized in terms of the oxidative stability of the oil. Results highlighted that oil droplets stabilized with GGM were stable during storage, against thermal treatment, upon addition into the beverages, and GGM protected cod liver oil against oxidation in drinkable yogurt. The results reported here highlight the vast potential for the use of wood lignocellulose-derived, multi-functional hydrocolloids in modern foods.Peer reviewe

    The addition of simvastatin administration to cold storage solution of explanted whole liver grafts for facing ischemia/reperfusion injury in an area with a low rate of deceased donation: a monocentric randomized controlled double-blinded phase 2 study.

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    BACKGROUND: Liver transplantation is the best treatment for end-stage liver disease. The interruption of the blood supply to the donor liver during cold storage damages the liver, affecting how well the liver will function after transplant. The drug Simvastatin may help to protect donor livers against this damage and improve outcomes for transplant recipients. The aim of this study is to evaluate the benefits of treating the donor liver with Simvastatin compared with the standard transplant procedure. PATIENT AND METHODS: We propose a prospective, double-blinded, randomized phase 2 study of 2 parallel groups of eligible adult patients. We will compare 3-month, 6-month, and 12-month graft survival after LT, in order to identify a significant relation between the two homogenous groups of LT patients. The two groups only differ by the Simvastatin or placebo administration regimen while following the same procedure, with identical surgical instruments, and medical and nursing skilled staff. To reach these goals, we determined that we needed to recruit 106 patients. This sample size achieves 90% power to detect a difference of 14.6% between the two groups survival using a one-sided binomial test. DISCUSSION: This trial is designed to confirm the effectiveness of Simvastatin to protect healthy and steatotic livers undergoing cold storage and warm reperfusion before transplantation and to evaluate if the addition of Simvastatin translates into improved graft outcomes. TRIAL REGISTRATION: ISRCTN27083228
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