Complex free energy landscapes in biaxial nematics and role of repulsive interactions : A Wang - Landau study

General quadratic Hamiltonian models, describing interaction between crystal molecules (typically with $D_{2h}$ symmetry) take into account couplings between their uniaxial and biaxial tensors. While the attractive contributions arising from interactions between similar tensors of the participating molecules provide for eventual condensation of the respective orders at suitably low temperatures, the role of cross-coupling between unlike tensors is not fully appreciated. Our recent study with an advanced Monte Carlo technique (entropic sampling) showed clearly the increasing relevance of this cross term in determining the phase diagram, contravening in some regions of model parameter space, the predictions of mean field theory and standard Monte Carlo simulation results. In this context, we investigated the phase diagrams and the nature of the phases therein, on two trajectories in the parameter space: one is a line in the interior region of biaxial stability believed to be representative of the real systems, and the second is the extensively investigated parabolic path resulting from the London dispersion approximation. In both the cases, we find the destabilizing effect of increased cross-coupling interactions, which invariably result in the formation of local biaxial organizations inhomogeneously distributed. This manifests as a small, but unmistakable, contribution of biaxial order in the uniaxial phase.The free energy profiles computed in the present study as a function of the two dominant order parameters indicate complex landscapes, reflecting the difficulties in the ready realization of the biaxial phase in the laboratory.Comment: 23 pages, 12 figure

Prescribing pattern of drugs in chronic kidney disease patients on hemodialysis at a tertiary care hospital

Background: CKD (chronic kidney disease) is a general term for heterogeneous disorders affecting kidney structure and its function. It is defined as either kidney damage or a decreased glomerular filtration rate of less than 60 mL/min/1.73m2 for 3 or more months. Objective of present work is to study the drug utilization pattern in chronic kidney disease patients undergoing hemodialysis.Methods: After taking the clearance and approval from the institutional ethics committee, a cross sectional prospective observational study conducted on chronic kidney disease (CKD) patients undergoing hemodialysis, in the department of nephrology, of Rajarajeshwari Medical College and Hospital, Bangalore. The data was analyzed descriptively.Results: Study included 52 patients, among them 41 males, 11were females, with a mean age of 47.6yrs. In our study large number pt were suffering from hypertension (HTN) 88.46% (46), in them the calcium channel blocker (CCB) 08.48% (38) was most commonly prescribed anti hypertensive drug. Around 1/3 of pt suffering from diabetes mellitus (DM) 36.53% (19) most of these patients were treated with them treated with oral hypoglycemic agents (OHA), and less than half of pt treated with insulin01.56% (07). Other drugs like phosphate binders (calcium carbonate & acetate) used in 11.16% (50), aspirin in 08.70% (39), statins in 10.04% (45) pt were being most commonly prescribed drugs.  Totally 448 drugs were prescribed In 52 pts Ie about 8.61 drugs / prescription, showing poly pharmacy.Conclusions: Patients undergoing hemodialysis with CKD will be having multiple diseases associated, regular monitoring and counseling regarding these diseases and its complication may reduce the incidence of CKD and the mortality and morbidity associated. The poly pharmacy noted in the study found inevitable because of the multifactorial etiologiesinvolved and needful multi-interventional approach towards it

Exclusion statistics: A resolution of the problem of negative weights

We give a formulation of the single particle occupation probabilities for a system of identical particles obeying fractional exclusion statistics of Haldane. We first derive a set of constraints using an exactly solvable model which describes an ideal exclusion statistics system and deduce the general counting rules for occupancy of states obeyed by these particles. We show that the problem of negative probabilities may be avoided with these new counting rules.Comment: REVTEX 3.0, 14 page