Generalised Kundt waves and their physical interpretation

We present the complete family of space-times with a non-expanding, shear-free, twist-free, geodesic principal null congruence (Kundt waves) that are of algebraic type III and for which the cosmological constant ($\Lambda_c$) is non-zero. The possible presence of an aligned pure radiation field is also assumed. These space-times generalise the known vacuum solutions of type N with arbitrary $\Lambda_c$ and type III with $\Lambda_c=0$. It is shown that there are two, one and three distinct classes of solutions when $\Lambda_c$ is respectively zero, positive and negative. The wave surfaces are plane, spherical or hyperboloidal in Minkowski, de Sitter or anti-de Sitter backgrounds respectively, and the structure of the family of wave surfaces in the background space-time is described. The weak singularities which occur in these space-times are interpreted in terms of envelopes of the wave surfaces.Comment: 16 pages including 2 figures. To appear in Classical and Quantum Gra

Exact Relativistic Static Charged Dust Disks and Non-axisymmetric Structures

The well-known ``displace, cut and reflect'' method used to generate disks from given solutions of Einstein field equations is applied to the superposition of twoextreme Reissner-Nordstrom black holes to construct disks made of charged dust and alsonon-axisymmetric planar distributions of charged dust on the z=0 plane. They are symmetric with respect to twoor one coordinate axes, depending whether the black holes have equal or unequal masses, respectively.For these non-axisymmetric distributions of matter we also study the effective potential for geodesic motion of neutral test particles.Comment: Classical and Quantum Gravity (in press). 15 pages, LaTex, 8 .eps fig

Geodesic motion in the Kundt spacetimes and the character of envelope singularity

We investigate geodesics in specific Kundt type N (or conformally flat) solutions to Einstein's equations. Components of the curvature tensor in parallelly transported tetrads are then explicitly evaluated and analyzed. This elucidates some interesting global properties of the spacetimes, such as an inherent rotation of the wave-propagation direction, or the character of singularities. In particular, we demonstrate that the characteristic envelope singularity of the rotated wave-fronts is a (non-scalar) curvature singularity, although all scalar invariants of the Riemann tensor vanish there.Comment: 21 pages, 3 figures. To appear in Class. Quantum Gra

Liver transplantation for type I and type IV glycogen storage disease

Progressive liver failure or hepatic complications of the primary disease led to orthotopic liver transplantation in eight children with glycogen storage disease over a 9-year period. One patient had glycogen storage disease (GSD) type I (von Gierke disease) and seven patients had type IV GSD (Andersen disease). As previously reported [19], a 16.5-year-old-girl with GSD type I was successfully treated in 1982 by orthotopic liver transplantation under cyclosporine and steroid immunosuppression. The metabolic consequences of the disease have been eliminated, the renal function and size have remained normal, and the patient has lived a normal young adult life. A late portal venous thrombosis was treated successfully with a distal splenorenal shunt. Orthotopic liver transplantation was performed in seven children with type N GSD who had progressive hepatic failure. Two patients died early from technical complications. The other five have no evidence of recurrent hepatic amylopectinosis after 1.1–5.8 postoperative years. They have had good physical and intellectual maturation. Amylopectin was found in many extrahepatic tissues prior to surgery, but cardiopathy and skeletal myopathy have not developed after transplantation. Postoperative heart biopsies from patients showed either minimal amylopectin deposits as long as 4.5 years following transplantation or a dramatic reduction in sequential biopsies from one patient who initially had dense myocardial deposits. Serious hepatic derangement is seen most commonly in types T and IV GSD. Liver transplantation cures the hepatic manifestations of both types. The extrahepatic deposition of abnormal glycogen appears not to be problematic in type I disease, and while potentially more threatening in type IV disease, may actually exhibit signs of regression after hepatic allografting

Temperature dependence of interlayer coupling in perpendicular magnetic tunnel junctions with GdOx barriers

Perpendicular magnetic tunnel junctions with GdOX tunneling barriers have shown a unique voltage controllable interlayer magnetic coupling effect. Here we investigate the quality of the GdOX barrier and the coupling mechanism in these junctions by examining the temperature dependence of the tunneling magnetoresistance and the interlayer coupling from room temperature down to 11 K. The barrier is shown to be of good quality with the spin independent conductance only contributing a small portion, 14%, to the total room temperature conductance, similar to AlOX and MgO barriers. The interlayer coupling, however, shows an anomalously strong temperature dependence including sign changes below 80 K. This non-trivial temperature dependence is not described by previous models of interlayer coupling and may be due to the large induced magnetic moment of the Gd ions in the barrier.Comment: 14 pages, 4 figure

Anomalous He-Gas High-Pressure Studies on Superconducting LaO1-xFxFeAs

AC susceptibility measurements have been carried out on superconducting LaO1-xFxFeAs for x=0.07 and 0.14 under He-gas pressures to about 0.8 GPa. Not only do the measured values of dTc/dP differ substantially from those obtained in previous studies using other pressure media, but the Tc(P) dependences observed depend on the detailed pressure/temperature history of the sample. A sizeable sensitivity of Tc(P) to shear stresses provides a possible explanation

Hepatitis b, c and hiv serological markers in children with sickle cell anaemia in a tertiary hospital, Gusau, North-Western Nigeria

Sickle Cell Anaemia patients are considered to be among the high-risk groups for hepatitis B and C viral infections. These viruses and HIV share common routes of transmission and similar risk factors and their infections coexist. Objective: This study was aimed at determining the seroprevalence of hepatitis B, C and HIV viral markers of infections in children with SCA. Methodology: A cross sectional Hospital based study conducted on 89 confirmed SCA Children aged 6 months – 13 years in steady state attending Haematology Clinic in a Specialist Hospital Gusau from July 2017 to March 2018. Approval for the study was obtained from the Research and Ethics Committee of the Hospital. The age, gender, history of blood transfusion, traditional scarification, uvulectomy, circumcision and immunization of the subjects were recorded. Serological test was carried out to determine the prevalence of hepatitis B, C and HIV using the viral markers and HIV 1& 2 rapid test kits. Results: Eighty-nine subjects were recruited with 46(51.7%) males and 43(48.3%) females. The mean age was 5.06 ±3.4 years. The seroprevalence of HBsAg, HBsAb, HBcAb, HBeAg, HBeAb, AntiHCV and HIV 1& 2 were 3(3.4%), 3(3.4%), 5(5.7%), 1(1.1%), 6(6.9%) and 0% respectively. No co-infection among the studied subjects. There is no significant difference in the age or gender distribution and seroprevalence of the viruses among SCA children. p = > 0.05 Conclusion: Hepatitis C infection is found to be high as opposed to Hepatitis B which is lower among SCA Children in this community

Gamma rays from dark matter annihilation in the Draco and observability at ARGO

The CACTUS experiment recently observed a gamma ray excess above 50 GeV from the direction of the Draco dwarf spheroidal galaxy. Considering that Draco is dark matter dominated the gamma rays may be generated through dark matter annihilation in the Draco halo. In the framework of the minimal supersymmetric extension of the standard model we explore the parameter space to account for the gamma ray signals at CACTUS. We find that the neutralino mass is constrained to be approximately in the range between 100 GeV ~ 400 GeV and a sharp central cuspy of the dark halo profile in Draco is necessary to explain the CACTUS results. We then discuss further constraints on the supersymmetric parameter space by observations at the ground based ARGO detector. It is found that the parameter space can be strongly constrained by ARGO if no excess from Draco is observed above 100 GeV.Comment: 15 pages, 4 figure

Simulation of Light Antinucleus-Nucleus Interactions

Creations of light anti-nuclei (anti-deuterium, anti-tritium, anti-He3 and anti-He4) are observed by collaborations at the LHC and RHIC accelerators. Some cosmic ray experiments are aimed to find the anti-nuclei in cosmic rays. To support the experimental studies of the anti-nuclei a Monte Carlo simulation of anti-nuclei interactions with matter is implemented in the Geant4 toolkit. The implementation combines practically all known theoretical approaches to the problem of antinucleon-nucleon interactions.Comment: 8 pages, 5 figure