Four - Fermi Theories in Fewer Than Four Dimensions

Four-fermi models in dimensionality $2<d<4$ exhibit an ultra-violet stable renormalization group fixed point at a strong value of the coupling constant where chiral symmetry is spontaneously broken. The resulting field theory describes relativistic fermions interacting non-trivially via exchange of scalar bound states. We calculate the $O(1/N_f)$ corrections to this picture, where $N_f$ is the number of fermion species, for a variety of models and confirm their renormalizability to this order. A connection between renormalizability and the hyperscaling relations between the theory's critical exponents is made explicit. We present results of extensive numerical simulations of the simplest model for $d=3$, performed using the hybrid Monte Carlo algorithm on lattice sizes ranging from $8^3$ to $24^3$. For $N_f=12$ species of massless fermions we confirm the existence of a second order phase transition where chiral symmetry is spontaneously broken. Using both direct measurement and finite size scaling arguments we estimate the critical exponents $\beta$, $\gamma$, $\nu$ and $\delta$. We also investigate symmetry restoration at non-zero temperature, and the scalar two-point correlation function in the vicinity of the bulk transition. All our results are in excellent agreement with analytic predictions, and support the contention that the $1/N_f$ expansion is accurate for this class of models.Comment: CERN-TH.6557/92 ILL-(TH)-92-\# 19, 60 pages, 18 figures (not included

Desde la diplomacia respaldada por la fuerza a la fuerza respaldada por la diplomacia: una mirada comparativa en las conversaciones de Bosnia y Kosovo

Este documento analiza de cerca las conversaciones de paz de Bosnia y Kosovo e intenta analizar por qué el primero fue un éxito y el segundo un fracaso en términos de poner fin a la guerra. Esto se hace a través del prisma de los tres enfoques teóricos principales en Relaciones Internacionales: realismo, liberalismo y constructivismo, así como la teoría de la negociación. El documento argumenta que, en esencia, la crisis yugoslava fue muy realista: un dilema de seguridad étnica causado por una emergente anarquía interna en Yugoslavia. Los conflictos resultantes presentaron a los estados liberales occidentales con un rompecabezas difícil de resolver: el equilibrio correcto entre el apoyo a la autodeterminación y la soberanía. El texto muestra que al tratar de resolver este enigma escogieron la manera intermedia de alternar políticas realistas y liberales, dejando como resultado soluciones imperfectas

From diplomacy backed by force to force backed by diplomacy: A comparative look at the Bosnia And Kosovo peace talks

This paper takes a closer look at the Bosnia and Kosovo peace talks and attempts to analyze why the former was a success and the letter a failure in terms of ending war. This is done through the prism of the three main theoretical approaches in IR - realism, liberalism, and constructivism - as well as the negotiation theory. The paper argues that in essence the Yugoslav crisis was very realist - an ethnic security dilemma caused by an emerging internal anarchy in Yugoslavia. The resulting conflicts presented liberal Western states with a difficult riddle of finding the right balance between support for self-determination and sovereignty. The paper shows that in trying to solve this riddle they chose the middle way of alternating between realist and liberal policies, leaving behind imperfect solutions

Desde la diplomacia respaldada por la fuerza a la fuerza respaldada por la diplomacia: una mirada comparativa en las conversaciones de Bosnia y Kosovo

Este documento analiza de cerca las conversaciones de paz de Bosnia y Kosovo e intenta analizar por qué el primero fue un éxito y el segundo un fracaso en términos de poner fin a la guerra. Esto se hace a través del prisma de los tres enfoques teóricos principales en Relaciones Internacionales: realismo, liberalismo y constructivismo, así como la teoría de la negociación. El documento argumenta que, en esencia, la crisis yugoslava fue muy realista: un dilema de seguridad étnica causado por una emergente anarquía interna en Yugoslavia. Los conflictos resultantes presentaron a los estados liberales occidentales con un rompecabezas difícil de resolver: el equilibrio correcto entre el apoyo a la autodeterminación y la soberanía. El texto muestra que al tratar de resolver este enigma escogieron la manera intermedia de alternar políticas realistas y liberales, dejando como resultado soluciones imperfectas

From diplomacy backed by force to force backed by diplomacy: A comparative look at the Bosnia And Kosovo peace talks

This paper takes a closer look at the Bosnia and Kosovo peace talks and attempts to analyze why the former was a success and the letter a failure in terms of ending war. This is done through the prism of the three main theoretical approaches in IR - realism, liberalism, and constructivism - as well as the negotiation theory. The paper argues that in essence the Yugoslav crisis was very realist - an ethnic security dilemma caused by an emerging internal anarchy in Yugoslavia. The resulting conflicts presented liberal Western states with a difficult riddle of finding the right balance between support for self-determination and sovereignty. The paper shows that in trying to solve this riddle they chose the middle way of alternating between realist and liberal policies, leaving behind imperfect solutions

Possible models of local news provision by radio in Scotland – a mixed methods study

Scotland does not have any public service radio on a local level, except for a few bulletins or programmes offered by BBC Radio Scotland on an opt-out basis. Scottish commercial radio stations do cover local issues but within brief hourly news bulletins, without any in-depth coverage, while community radio by and large lacks resources for any news coverage of its own. Through a review of the existing literature on the role of media in democracy, and in particular the role of local radio, interviews with stakeholders and experts and history, and focus groups with ordinary people, the present study formulates several possible solutions for future local news provision by radio in Scotland

FOLLOW-UP OF BIOCHEMICAL PARAMETERS AND INTENSITY OF OXIDATIVE STRESS IN PATIENTS WITH EXTRAHEPATHIC CHOLESTASIS

In cholestasis, due to impossibility of gall flow into duodenum, there occurs a subsequent return of gall constituents to hepatocytes and circulation. Extrahepatic cholestasis is the result of mechanic obstacle of gall flow through ductus hepaticus, choledochus or papilla Vateri, leading to the occurrence of manifest icterus. In cases leading to liver damage, hydrophobic gall salts and non-conjugated bilirubins have the most important toxic effects.The aim of this study was to follow up the biochemical parameters, enzyme activity AST, ALT, *-GT and AF, bilirubin concentration and albumins, and intensity of oxidative stress in blood plasma in patients with different types of extrahepatic cholestasis.The study included 60 subjects divided into two groups. The first one was control group (30 healthy subjects), while II group involved 30 patients with intraluminar extrahepatic obstruction.Significant increase of enzyme activity of AST, ALT, *-GT and AF in plasma of cholestatic patients was present in comparison to the control group (p< 0,001). The levels of total direct and indirect bilirubin in plasma of cholestatic patients increased (p<0,001) when compared to the control group. The level of albumin in plasma of cholestatic patients significantly decreased in comparison to the control group (p<0,05). The intensity of oxidative stress measured through the levels of malondialdehide (MDA) and carbonyl group concentration in plasma of cholestatic patients increased (p<0,001) when compared to the control group.Significant increase of cholestasis enzyme markers (AST, ALT, *-GT and AF) and bilirubin levels in blood plasma was noticed in patients with extrahepatic cholestasis. Cholestasis leads to significant disorders of synthetic function of the liver that are manifested by decrease of albumin concentration in plasma

Phase Transitions at Finite Temperature and Dimensional Reduction for Fermions and Bosons

In a recent Letter we discussed the fact that large-$N$ expansions and computer simulations indicate that the universality class of the finite temperature chiral symmetry restoration transition in the 3D Gross-Neveu model is mean field theory. This was seen to be a counterexample to the standard 'sigma model' scenario which predicts the 2D Ising model universality class. In this article we present more evidence, both theoretical and numerical, that this result is correct. We develop a physical picture for our results and discuss the width of the scaling region (Ginzburg criterion), $1/N$ corrections, and differences between the dynamics of BCS superconductors and Gross-Neveu models. Lattices as large as $12 \times 72^2$ are simulated for both the $N=12$ and $N=4$ cases and the numerical evidence for mean field scaling is quite compelling. We point out that the amplitude ratio for the model's susceptibility is a particulartly good observable for distinguishing between the dimensional reduction and the mean field scenerios, because this universal quantity differs by almost a factor of $20$ in the two cases. The simulations are done close to the critical point in both the symmetric and broken phases, and correlation lengths of order $10$ are measured. The critical indices $\beta_{mag}$ and $\delta$ also pick out mean field behavior. We trace the breakdown of the standard scenario (dimensional reduction and universality) to the composite character of the mesons in the model. We point out that our results should be generic for theories with dynamical symmetry breaking, such as Quantum Chromodynamics. We also simulated the $O(2)$ model on $8 \times 16^3$ lattices to establish that our methods give the results of dimensional reduction in purely bosonicComment: 47 pages, latex, 23 figures in one uuencoded fil