2,976 research outputs found
IrSr_2Sm_{1.15}Ce_{0.85}Cu_{2.175}O_{10}: A Novel Reentrant Spin-Glass Material
A new iridium containing layered cuprate material,
IrSr_2Sm_{1.15}Ce_{0.85}Cu_{2.175}O_{10, has been synthesized by conventional
ambient-pressure solid-state techniques. The material's structure has been
fully characterized by Rietveld refinement of high resolution synchrotron X-ray
diffraction data; tilts and rotations of the IrO_6 octahedra are observed as a
result of a bond mismatch between in-plane Ir-O and Cu-O bond lengths.
DC-susceptibility measurements evidence a complex set of magnetic transitions
upon cooling that are characteristic of a reentrant spin-glass ground-state.
The glassy character of the lowest temperature, Tg=10 K, transition is further
confirmed by AC-susceptibility measurements, showing a characteristic frequency
dependence that can be well fitted by the Vogel-Fulcher law and yields a value
of \Delta_(T_f)/[T_f \Delta log({\omega})] =0.015(1), typical of dilute
magnetic systems. Electronic transport measurements show the material to be
semiconducting at all temperatures with no transition to a superconducting
state. Negative magnetoresistance is observed when the material is cooled below
25 K, and the magnitude of this magnetoresistance is seen to increase upon
cooling to a value of MR = -9 % at 8 K
Sequence variation in the haemagglutinin-neuraminidase gene of human parainfluenza virus type 3 isolates in the UK
The sequence variation in a 934 base-pair region of the gene encoding the haemagglutinin-neuraminidase of five human parainfluenza virus type 3 (HPIV3) isolates was determined together with that of a prototype UK strain. All of the clinical isolates were from the Manchester area of the UK and were obtained in 1990. 1991 and 1993. The gene segment was amplified by the polymerase chain reaction using HPIVB-specific oligonucleotide primers. The nucleotide homology of the strains was high, around 99% and specific differences in the UK sequences when compared with that of the US prototype strain were identified. In addition, a number of isolate-specific differences were seen. No correlation was detected between the observed nucleotide mutations and the year of isolation, which supports the hypothesis that HPIV3 shows cocirculation of a heterogeneous population of viruses rather than varying with time in a linear fashion. However, the data suggested that geographically-defined genetic lineages of HPIV3 may exist
Research and development of high-performance light-weight fuel cell electrodes final report, nov. 1, 1963 - oct. 31, 1964
High performance light weight fuel cell electrode developmen
Prevention of folate deficiency by food fortification
The antimegaloblastic effect of cooked folic acid-fortified maize meal was tested by feeding the meal to 5 lactating patients with folate-deficient megaloblastic anaemia. The dose of folic acid in the meal before cooking varied fromĀ 100 to Ā·500 Āµg daily. One patient who received 100 Āµg daily had a suboptimal haematological response. Meal containing 300 Āµg and 500 Āµg daily produced optimalĀ haematological response in all 4 patients so treated, and there was no secondary reticulocyte response in the 2Ā patients subsequently given pharmacological doses of folic acid. It is concluded that the fortified meal after cooking is an effective antimegaloblastic agent.S. Afr. Med. J., 48, 1795 (1974)
The resistance of randomly grown trees
Copyright @ 2011 IOP Publishing Ltd. This is a preprint version of the published article which can be accessed from the link below.An electrical network with the structure of a random tree is considered: starting from a root vertex, in one iteration each leaf (a vertex with zero or one adjacent edges) of the tree is extended by either a single edge with probability p or two edges with probability 1 ā p. With each edge having a resistance equal to 1 omega, the total resistance Rn between the root vertex and a busbar connecting all the vertices at the nth level is considered. A dynamical system is presented which approximates Rn, it is shown that the mean value (Rn) for this system approaches (1 + p)/(1 ā p) as n ā ā, the distribution of Rn at large n is also examined. Additionally, a random sequence construction akin to a random Fibonacci sequence is used to approximate Rn; this sequence is shown to be related to the Legendre polynomials and its mean is shown to converge with |(Rn) ā (1 + p)/(1 ā p)| ā¼ nā1/2.Engineering and Physical Sciences Research Council (EPSRC
Promotion of cooperation induced by nonlinear attractive effect in spatial Prisoner's Dilemma game
We introduce nonlinear attractive effects into a spatial Prisoner's Dilemma
game where the players located on a square lattice can either cooperate with
their nearest neighbors or defect. In every generation, each player updates its
strategy by firstly choosing one of the neighbors with a probability
proportional to denoting the attractiveness of the
neighbor, where is the payoff collected by it and
(0) is a free parameter characterizing the extent of the nonlinear
effect; and then adopting its strategy with a probability dependent on their
payoff difference. Using Monte Carlo simulations, we investigate the density
of cooperators in the stationary state for different values of
. It is shown that the introduction of such attractive effect
remarkably promotes the emergence and persistence of cooperation over a wide
range of the temptation to defect. In particular, for large values of ,
i.e., strong nonlinear attractive effects, the system exhibits two absorbing
states (all cooperators or all defectors) separated by an active state
(coexistence of cooperators and defectors) when varying the temptation to
defect. In the critical region where goes to zero, the extinction
behavior is power law-like , where the
exponent accords approximatively with the critical exponent
() of the two-dimensional directed percolation and depends
weakly on the value of .Comment: 7 pages, 4 figure
EĀ“ chelle diagrams and period spacings of g modes in: Doradus stars from four years of Kepler observations
We use photometry from the Kepler Mission to study oscillations in Doradus stars. Some stars show remarkably clear sequences of g modes and we use period Ā“echelle diagrams to measure period spacings and identifyrotationally split multiplets with ` = 1 and ` = 2.We find small deviations from regular period spacings that arise from the gradient in the chemical composition just outside the convective core. We also find stars for which the period spacing shows a strong linear trend as a function of period, consistent with relatively rapid rotation. Overall, th
Prevention of folate deficiency by food fortification
Red cell folate levels were measured for 6 weeks in an index member and the oldest member of each of 6 families who had been given folic acid-fortified maize meal for use in the home. Five of the index subjects were pregnant and one was lactating. The amount of folic acid added to the maize was calculated so that each adult would receive 500 /Lg folic acid daily. In the index subjects of 5 of the 6 families studied, red cell folate levels rose significantly. The changes in red cell folate levels suggest that pregnant women consume more maize meal than elderly subjects. This possibility would tend toĀ increase the margin of safety when folic acid-fortified foods are consumed by populations in which vitamin B12 deficient megaloblastic anaemia is found.S. Afr. Med. J., 48, 1763 (1974)
Modelling plausible scenarios for the Omicron SARS-CoV-2 variant from early-stage surveillance
In this paper we used an adapted version of an existing simulation model of
SARS-CoV-2 transmission in Scotland to investigate the rise of the Omicron
variant of concern, in order to evaluate plausible scenarios for transmission
advantage and vaccine immune escape relative to the Delta variant. We also
explored possible outcomes of different levels of imposed non-pharmaceutical
intervention. The initial results of these scenarios were used to inform the
Scottish Government in the early outbreak stages of the Omicron variant.
We use an explicitly spatial agent-based simulation model combined with
spatially fine-grained COVID-19 observation data from Public Health Scotland.
Using the model with parameters fit over the Delta variant epidemic, some
initial assumptions about Omicron transmission advantage and vaccine escape,
and a simple growth rate fitting procedure, we were able to capture the initial
outbreak dynamics for Omicron. We also find the modelled dynamics hold up to
retrospective scrutiny.
We found that the modelled imposition of extra non-pharmaceutical
interventions planned by the Scottish Government at the time would likely have
little effect in light of the transmission advantage held by the Omicron
variant and the fact that the planned interventions would have occurred too
late in the outbreak's trajectory. Finally, we found that any assumptions made
about the projected distribution of vaccines in the model population had little
bearing on the outcome, in terms of outbreak size and timing, rather that the
detailed landscape of immunity prior to the outbreak was of far greater
importance
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