Thermal Equilibration of 176-Lu via K-Mixing

In astrophysical environments, the long-lived (\T_1/2 = 37.6 Gy) ground state of 176-Lu can communicate with a short-lived (T_1/2 = 3.664 h) isomeric level through thermal excitations. Thus, the lifetime of 176-Lu in an astrophysical environment can be quite different than in the laboratory. We examine the possibility that the rate of equilibration can be enhanced via K-mixing of two levels near E_x = 725 keV and estimate the relevant gamma-decay rates. We use this result to illustrate the effect of K-mixing on the effective stellar half-life. We also present a network calculation that includes the equilibrating transitions allowed by K-mixing. Even a small amount of K-mixing will ensure that 176-Lu reaches at least a quasi-equilibrium during an s-process triggered by the 22-Ne neutron source.Comment: 9 pages, 6 figure

Liouville Field Theory of Fluctuating Loops

Effective field theories of two-dimensional lattice models of fluctuating loops are constructed by mapping them onto random surfaces whose large scale fluctuations are described by a Liouville field theory. This provides a geometrical view of conformal invariance in two-dimensional critical phenomena and a method for calculating critical properties of loop models exactly. As an application of the method, the conformal charge and critical exponents for two mutually excluding Hamiltonian walks on the square lattice are calculated.Comment: 4 RevTex pages, 1 eps figur

Statistical Topography of Glassy Interfaces

Statistical topography of two-dimensional interfaces in the presence of quenched disorder is studied utilizing combinatorial optimization algorithms. Finite-size scaling is used to measure geometrical exponents associated with contour loops and fully packed loops. We find that contour-loop exponents depend on the type of disorder (periodic ``vs'' non-periodic) and they satisfy scaling relations characteristic of self-affine rough surfaces. Fully packed loops on the other hand are unaffected by disorder with geometrical exponents that take on their pure values.Comment: 4 pages, REVTEX, 4 figures included. Further information can be obtained from [email protected]

Monte-Carlo study of scaling exponents of rough surfaces and correlated percolation

We calculate the scaling exponents of the two-dimensional correlated percolation cluster's hull and unscreened perimeter. Correlations are introduced through an underlying correlated random potential, which is used to define the state of bonds of a two-dimensional bond percolation model. Monte-Carlo simulations are run and the values of the scaling exponents are determined as functions of the Hurst exponent H in the range -0.75 <= H <= 1. The results confirm the conjectures of earlier studies

Early Neuroendoscope-assisted Evacuation of Spontaneous Intracranial Hematomas. Preliminary Report

Purpose: The surgical techniques, effectiveness and indications of microsurgical neuroendoscopic assisted evacuation of spontaneous intracranial hematomas (SICH) is still uncertain. This minimal invasive technique remains investigational and controversal with regard to patient selection, timing of operation and method of the management. The purpose of this study was to investigate the early postoperative results in patients with SICH underwent endoscopic evacuation and to give evaluation and eventual prognosis of the clinical outcomes after this procedure.Material and Methods: A retrospective analysis of 56 patients SICH treated in the Neurosurgical clinic with endoscopic assisted evacuation was performed. Hematoma volume and its localization (subcortical – 11 patients, in basal ganglia – 12 – 7 of them with propagation to ventricular system, 6 infratentorial and 27 subdural), comorbidity, clinical featuresand timing of surgical procedures was made. The GCS rate by admission and GOS by discharging of patients was analyzed, also the postoperative complications and causes of death. Results: 52 patients (92, 9%) were operated within the first 24 hours of the onset. Patients operated between the 12 and 24 hours had better outcome in comparison to these operated after the 24 hours period. The authors analyzed their experience with endoscopic technique, effectiveness of the method, results and complications. Mortality rate in our series was 23,2% (13 patients). The causes of surgical complications and causes of death were analyzed.Conclusion: The endoscopic assisted evacuation of SICH is a short, safe and very effective method when the surgical procerure is provided within the first 12–24 hours. Our results showed that early and complete evacuation of hematoma volume may promote to recovery of the general condition of the patient and improved outcomes

The packing of two species of polygons on the square lattice

We decorate the square lattice with two species of polygons under the constraint that every lattice edge is covered by only one polygon and every vertex is visited by both types of polygons. We end up with a 24 vertex model which is known in the literature as the fully packed double loop model. In the particular case in which the fugacities of the polygons are the same, the model admits an exact solution. The solution is obtained using coordinate Bethe ansatz and provides a closed expression for the free energy. In particular we find the free energy of the four colorings model and the double Hamiltonian walk and recover the known entropy of the Ice model. When both fugacities are set equal to two the model undergoes an infinite order phase transition.Comment: 21 pages, 4 figure

Zero-Temperature Phase Transitions of Antiferromagnetic Ising Model of General Spin on a Triangular Lattice

We map the ground-state ensemble of antiferromagnetic Ising model of spin-S on a triangular lattice to an interface model whose entropic fluctuations are proposed to be described by an effective Gaussian free energy, which enables us to calculate the critical exponents of various operators in terms of the stiffness constant of the interface. Monte Carlo simulations for the ground-state ensemble utilizing this interfacial representation are performed to study both the dynamical and the static properties of the model. This method yields more accurate numerical results for the critical exponents. By varying the spin magnitude in the model, we find that the model exhibits three phases with a Kosterlitz-Thouless phase transition at 3/2<S_{KT}<2 and a locking phase transition at 5/2 < S_L \leq 3. The phase diagram at finite temperatures is also discussed.Comment: 15 pages, LaTeX; 10 figures in PostScript files; The revised version appears in PRB (see Journal-ref). New electronic address of first author, [email protected]