What makes a crystal supersolid ?

For nearly half a century the supersolid phase of matter has remained mysterious, not only eluding experimental observation, but also generating a great deal of controversy among theorists. Recent discovery of what is interpreted as a non-classical moment of inertia at low temperature in solid He-4 has elicited much excitement as a possible first observation of a supersolid phase. In the two years following the discovery, however, more puzzles than answers have been provided to the fundamental issue of whether the supersolid phase exists, in helium or any other naturally occurring condensed matter system. Presently, there is no established theoretical framework to understand the body of experimental data on He-4. Different microscopic mechanisms that have been suggested to underlie superfluidity in a perfect quantum crystal do not seem viable for \he4, for which a wealth of experimental and theoretical evidence points to an insulating crystalline ground state. This perspective addresses some of the outstanding problems with the interpretation of recent experimental observations of the apparent superfluid response in He-4 (seen now by several groups) and discusses various scenarios alternative to the homogeneous supersolid phase, such as superfluidity induced by extended defects of the crystalline structure which include grain boundaries, dislocations, anisotropic stresses, etc. Can a metastable superfluid "glassy" phase exist, and can it be relevant to some of the experimental observations ? One of the most interesting and unsolved fundamental questions is what interatomic potentials, given the freedom to design one, can support an ideal supersolid phase in continuous space, and can they be found in Nature.Comment: Perspective to appear in Advances in Physics, 25 pages, 7 figure

Higher moments of spin-spin correlation functions for the ferromagnetic random bond Potts model

Using CFT techniques, we compute the disorder-averaged p-th power of the spin-spin correlation function for the ferromagnetic random bonds Potts model. We thus generalize the calculation of Dotsenko, Dotsenko and Picco, where the case p=2 was considered. Perturbative calculations are made up to the second order in epsilon (epsilon being proportional to the central charge deviation of the pure model from the Ising model value). The explicit dependence of the correlation function on $p$ gives an upper bound for the validity of the expansion, which seems to be valid, in the three-states case, only if p-alpha in final formula

CYSTATHIONASE ACTIVITY OF ALBINO RATS FED ON RICH PROTEIN DIET IN EXPERIMENTAL MANGANESE POISONING

No abstrac

Harmonic oscillators in the Nos\'e - Hoover thermostat

We study the dynamics of an ensemble of non-interacting harmonic oscillators in a nonlinear dissipative environment described by the Nos\'e - Hoover model. Using numerical simulation we find the histogram for total energy, which agrees with the analysis of the Nos\'e - Hoover equations effected with the method of averaging. The histogram does not correspond to Gibbs' canonical distribution. We have found oscillations at frequency proportional to $\sqrt{\alpha/m}$, $\alpha$ the dissipative parameter of thermostat and $m$ the characteristic mass of particle, about the stationary state corresponding to equilibrium. The oscillations could have an important bearing upon the analysis of simulating molecular dynamics in the Nos\'e - Hoover thermostat.Comment: 7 pages, 4 figure

THE EFFECT OF EXPERIMENTAL CHLORINE POISONING ON CERTAIN AMINO ACIDS AND ENZYMES IN RATS, FED ON RICH PROTEIN RATION

No abstract

Olovo i kadmij u cigaretama i dimnom kondenzatu

The cigarettes of three commercial brands (belonging to JUS quality classes E, II and IV) were analysed for cadmium and lead in tobacco, butts and crude smoke condensate. Metal fractions transferred from the cigarette tobacco to the smoke as well as metal retentions in the butts were calculated from the analytical results. Statistical analyses revealed a significant dependence of all observables on the cigarette quality class.Metodom inverzne voltammetrije na visećoj živinoj kapi (DPASV) određene su količine kadmija i olova u cigaretama triju vrsta (kvalitetni razredi prema JUS-u: Extra, II i IV). Pored duhana, papira i filtarskih čepića analizirani su i opušci i sirovi dimni kondenzat. Iz analističkih rezultata izračunana je frakcija prijenosa metala iz duhana u dimni kondenzat kao J retencija metala u opušku. Statističkim analizama utvrđena je ovisnost svili opservabli o kvalitetnom razredu cigarete

THE CONTENT OF CERTAIN AMINO ACIDS IN THE BLOOD LND LIVER OF WHITE ALBINO RATS, FED ON FATTY RATIONS DURING EXPERIMENTAL LEAD POISONING (HISTIDINE, ARGININE, VALINE) : Communication II

No abstract

CHANGES IN THE CONTENT OF CERTAIN AMINO ACIDS IN THE BLOOD AND LIVER OF WHITE ALBINO RATS, FED ON PROTEIN RATION DURING EXPERIMENTAL LEAD INTOXICATION : Communication II - histidine, arginine and valine

No abstract

A high incidence of native portal vein thrombosis in veterans undergoing liver transplantation

The incidence of native portal vein thrombosis (PVT) in liver transplant recipients has been reported to range from 2.1 to 13.8%. We have identified an inordinately high incidence of PVT in a consecutive series of U.S. veterans receiving liver transplants. Between October 1989 and February 1994, 88 consecutive U.S. veterans received 99 orthotopic liver transplants under primary Tacrolimus (Prograf, formerly FK506) based immunosuppression. A number of clinical features were examined in an effort to identify risk factors for PVT and outcome was compared to patients without PVT. Native PVT was present in 23/88 (26%) patients. All of these patients were male U.S. veterans with a mean age of 47 years. When compared to the 65 patients without PVT, we found no significant difference with respect to underlying liver disease, age, Childs-Pugh score (mean = 12), UNOS status as defined prior to April 1995 (95% UNOS 3 or 4), previous abdominal surgery, or liver volume. Median blood loss for patients with PVT (21 units of packed red blood cells) was greater than for those without PVT (14 units, P = 0.04). Portal thrombectomy was performed in 11 patients, 11 patients required mesoportal jump grafts, and 1 patient had an interposition graft. Standard veno-venous bypass was used in 10 patients with single bypass utilized for the remainder. Actuarial patient survival for all patients at 1, 2, and 4 years was 88, 85, and 79%, respectively. There was no significant difference in patients with or without PVT. Patients with PVT had poorer graft survival than patients without PVT (86% vs 65%, 1 year; 81% vs 65%, 2 years; 81% vs 61%, 4 years; P = 0.03); however, this was not related to technical problems with the portal venous inflow. PVT occurred in 26% of U.S. veterans undergoing liver transplantation. These patients bad significantly higher operative blood loss and poorer graft survival. The high incidence of postnecrotic cirrhosis in a predominantly male group of patients with advanced disease, as is evident by the high mean Childs-Pugh score and UNOS status, perhaps accounts for our observations

Decreased incidence of viral infections in liver transplant recipients - Possible effects of FK506?

Cytomegalovirus (CMV) is a major infectious complication of organ transplantation and its incidence is influenced by the type and intensity of immunosuppressive therapy employed. Using a new immunosuppressive agent FK506, CMV infection was observed in 30% and CMV disease in 15% of the 26 liver transplant recipients. Delayed onset of CMV disease was noted; the mean time to the occurrence of CMV disease being 137 days posttransplantation. No graft loss or mortality could be attributed to CMV infection. Mucocutaneous herpes simplex virus (HSV) infections were encountered in 19% of the patients, while no disease could be attributed to varicella zoster virus or Epstein-Barr virus (EBV). The contribution of FK506 to a decrease in viral morbidity and associated mortality bears further investigation. © 1994 Plenum Publishing Corporation