Developing a finite difference time domain parallel code for nuclear electromagnetic field Simulation

A two dimensional finite-difference time-domain code has been developed for complete simulation of nuclear electromagnetic pulse (NEMP) originating from an atmospheric nuclear detonation. The modules of NEMP simulation code describing various physics aspects are discussed. Typical results of the serial code for Compton current estimated from detailed neutron-gamma transport, induced air conductivity and electromagnetic fields are presented. The need for parallelizing such code has been explained. The parallel implementation using domain decomposition technique of message passing interface paradigm is described. The efficiency of the parallel code has been studied with increasing number of processors. The limitations of speed-up due to communication times are discussed.     

Adaptive channel estimation using cyclic prefix in multicarriermodulation system

Multicarrier modulation (MCM) is a promising technique for high rate data transmission and the channel estimation is very important for the implementation of MCM. We found that the cyclic prefix, originally used solely to reduce the intersymbol interference (ISI), can be viewed as a source of channel information. Based on this observation, we propose an adaptive channel estimation algorithm using the cyclic prefix. This algorithm can adaptively track the channel variation without additional training sequences     

Mass Flow through Solid 4H

We continue our solid ⁴He flow experiments in which we grow solid helium samples at constant temperature in the hcp region of the phase diagram. We exploit the properties of liquid helium in a confined geometry (porous Vycor glass), and induce a mass flow through the solid at pressures higher than the bulk melting pressure. We previously observed flow, but our temperature was limited to T≥350 mK. At T≈400 mK it was found that the flow ceased at P≈27 bar, and no flow was observed for T>550 mK. We have begun to extend our measurements to lower temperatures, and our data show that at lower temperatures we observe flow at higher pressures.     

Prostaglandin F and progesterone secretion by porcine endometrium and corpus luteum in vitro

Slices of porcine endometrium and corpus luteum tissue obtained from mature sows throughout the luteal phase of the oestrous cycle were incubated in culture medium which was analysed at regular intervals over a period of 8 hours for prostaglandin F and progesterone. Prostaglandin F secretion was greatest by endometrium obtained during the mid III to late I luteal stage of the cycle and the increased levels secreted by this tissue were paralleled by high levels of secretion from corpus luteum tissue. The addition of indomethacin (10 mug/ml) to the culture medium completely abolished prostaglandin F secretion by both endometrium and luteal tissue indicating that the high levels of the prostaglandin were due to synthesis. Progesterone secretion by the corpus luteum was maximal from early luteal tissue and had declined to considerably lower levels by late stage tissue when prostaglandin secretion was greatest. The possible physiological significance of luteal prostaglandin F secretion is discussed.     

Awareness and dreams during general anaesthesia for Caesarian section a study of incidence

One hundred Nigerian patients presenting for emergency caesarian section were interviewed within the first 24 hours post-operatively. The purpose was to determine the incidence of awareness and dreams. The standard anaesthetic technique consisted of atropine 0.6 mg and thiopentone 250 mg given intravenously at the time of induction, suxamethonium bromide 40 mg intravenously to facilitate tracheal intubation and nitrous oxide/oxygen/pancuronium for maintenance. The incidence of awareness was 4% while the incidence of dreaming was 17%. Most (94%) of the patients said they dreamed only occasionally at home and of these, 15% claimed they dreamed more frequently when pregnant than when not pregnant.     

The effect of paraben preservatives on albumin binding of bilirubin

The effect of sodium taurocholate in stepwise increasing infusion rates, 0.3 to 9.6 mumoles per min per kg, on the biliary excretion rate of iodipamide was investigated in 6 dogs (10 experiments) with complete bile diversion under general anesthesia. Iodipamide was administered intravenously with an initial priming dose of 33 mumoles per kg followed by a constant infusion of 1.3 mumoles per min per kg. Although the bile flow continuously increased with an increasing taurocholate dose, the iodipamide excretion rate reached a plateau with a 0.6 mumoles per min per kg of taurcholate infusion, which was 20% higher than with the lowest taurocholate dose. With a taurocholate dose over 2.4 mumoles per min per kg, a significant decrease in the iodipamide rate was found, amounting to 22% of its maximum value with the largest taurocholate dose. The bile iodipamide concentration was already at its maximum with the lowest taurocholate dose, and it decreased with an increasing taurocholate dose. Since the bile iodipamide concentration is probably the most important determinant in clinical cholangiography, low bile salt plasma levels should result in the best radiographic visualization of the biliary tree.     

Serial measurement of arterial plasma progesterone levels throughout gestation and parturition in individual rats

Daily blood samples were taken from 6, chronically cannulated, fully conscious rats to measure plasma progesterone levels throughout gestation. Progesterone levels in individual rats fluctuated by up to 28 ng/ml per day, but tended to be consistently higher or lower than the group mean. The accuracy of predicting progesterone levels in individual rats from previous values was examined. Progesterone levels on day 7 of gestation were negatively correlated with foetal weights near term. There was little indication that high progesterone levels at any stage of gestation lead to increased foetal or placental weights. Progesterone levels on day 17 were positively correlated with the number of corpura lutea but there was little relationship between progesterone and either the number or total mass of the placentas. Serial blood samples taken from a second group of 6 rats at 2 hourly intervals showed that the time between the major fall in progesterone levels to below 12 ng/ml and the onset of parturition was relatively constant (varying by only 8 h) despite a 29 h range in the total length of gestation.     

Neisseria lactamica meningitis

Neisseria lactamica was recovered from the blood and cerebrospinal fluid of a 7-month-old girl with acute purulent meningitis. The isolate was identified initially as N meningitidis. However, additional biochemical testing at the Center for Disease Control showed that the organism fermented lactose and produced beta-D-galactosidase, thereby confirming its identity as N lactamica.     

The effects of drugs and anaesthetic agents on the urinary bladder and sphincters

The influence of sedative, anaesthetic and neuromuscular blocking drugs on diagnostic urethral pressure profiles and cystometrograms has been investigated. These agents have marked effects on the results obtained; in particular, the urethral pressure profile was raised by opiates and lowered by anaesthetic induction agents. Bladder capacity as measured by the cystometrogram was greatly increased by halothane. These findings indicate that urodynamic studies should be performed only on conscious unsedated patients.     

Acute reductions in serum testosterone levels by narcotics in the male rat: stereospecificity, blockade by naloxone and tolerance

The effects of a single injection of morphine (20 mg/kg) on serum testosterone levels were examined in the male rat. Within 2 hours after the morphine injection, testosterone levels were significantly lower than control levels. The decline in testosterone levels reached a maximum 4 hours after the administration of morphine, at which time testosterone levels were reduced by more than 85% with respect to controls. The ability of a large number of narcotics to depress serum testosterone levels, 4 hours after their administration, was also examined. All narcotics depressed testosterone levels significantly and their potency relative to morphine was comparable to that observed in several other preparations, such as the guinea-pig ileum and mouse vas deferens. The testosterone-depleting effects of the narcotics appear to represent specific narcotic effects since the (-)-isomers of the narcotics were considerably more potent than the (+)-isomers, naloxone competitively inhibited the effects of morphine on testosterone levels and tolerance developed to the testosterone-depleting effects of these drugs. Acute treatment with morphine also lowered serum luteinizing hormone levels, and this reduction preceded the fall in testosterone levels by 1 to 2 hours.