60 research outputs found
Orbital Ordering Structures in (Nd,Pr)0.5Sr0.5MnO3 Manganite Thin Films on Perovskite (011) Substrates
Structural study of orbital-ordered manganite thin films has been conducted
using synchrotron radiation, and a ground state electronic phase diagram is
made. The lattice parameters of four manganite thin films, Nd0.5Sr0.5MnO3
(NSMO) or Pr0.5Sr0.5MnO3 (PSMO) on (011) surfaces of SrTiO3 (STO) or
[(LaAlO3){0.3}(SrAl0.5Ta0.5O3){0.7}] (LSAT), were measured as a function of
temperature. The result shows, as expected based on previous knowledge of bulk
materials, that the films' resistivity is closely related to their structures.
Observed superlattice reflections indicate that NSMO thin films have an
antiferro-orbital-ordered phase as their low-temperature phase while PSMO film
on LSAT has a ferro-orbital-ordered phase, and that on STO has no
orbital-ordered phase. A metallic ground state was observed only in films
having a narrow region of A-site ion radius, while larger ions favor
ferro-orbital-ordered structure and smaller ions stabilize
antiferro-orbital-ordered structure. The key to the orbital-ordering transition
in (011) film is found to be the in-plane displacement along [0-1 1] direction.Comment: 19pages, 11 figure
High magnetic field transport measurement of charge-ordered PrCaMnO strained thin films
We have investigated the magnetic-field-induced phase transition of
charge-ordered (CO) PrCaMnO thin films, deposited onto
(100)-oriented LaAlO and (100)-oriented SrTiO substrates using the
pulsed laser deposition technique, by measuring the transport properties with
magnetic fields up to 22T. The transition to a metallic state is observed on
both substrates by application of a critical magnetic field ( at 60K).
The value of the field required to destroy the charge-ordered insulating state,
lower than the bulk compound, depends on both the substrate and the thickness
of the film. The difference of the critical magnetic field between the films
and the bulk material is explained by the difference of in-plane parameters at
low temperature (below the CO transition). Finally, these results confirm that
the robustness of the CO state, depends mainly on the stress induced by the
difference in the thermal dilatations between the film and the substrate.Comment: 10 pages, 6 figures. To be published in Phys. Rev.
How the risk of liver cancer changes after alcohol cessation: A review and meta-analysis of the current literature
<p>Abstract</p> <p>Background</p> <p>It is well established that drinking alcohol raises the risk of liver cancer (hepatocellular carcinoma). However, it has not been sufficiently established as to whether or not drinking cessation subsequently reduces the risk of liver cancer and if it does reduce the risk how long it takes for this heightened risk to fall to that of never drinkers. This question is important for effective policy design and evaluation, to establish causality and for motivational treatments.</p> <p>Methods</p> <p>A systematic review and meta-analysis using the current available evidence and a specific form of Generalised Least Squares is performed to assess how the risk of liver cancer changes with time for former drinkers.</p> <p>Results</p> <p>Four studies are found to have quantified the effect of drinking cessation on the risk of liver cancer. The meta-analysis suggests that the risk of liver cancer does indeed fall after cessation by 6-7% a year, but there remains a large uncertainty around this estimate both statistically and in its interpretation. As an illustration it is estimated that a time period of 23 years is required after drinking cessation, with a correspondingly large 95% confidence interval of 14 to 70 years, for the risk of liver cancer to be equal to that of never drinkers.</p> <p>Conclusion</p> <p>This is a relatively under researched area and this is reflected in the uncertainty of the findings. It is our view that it is not possible to extrapolate the results found here to the general population. Too few studies have addressed this question and of the studies that have, all have significant limitations. The key issue amongst the relevant studies is that it appears that current drinkers, abstainers and former drinkers are not composed of, or effectively adjusted to be, similar populations making inferences about risk changes impossible. This is a very difficult area to study effectively, but it is an important topic. More work is required to reduce both statistical uncertainty and tackle the various study limitations this paper highlights and until this is done, the current result should be considered preliminary.</p
Liver cancer risk, coffee, and hepatitis C virus infection: a nested case–control study in Japan
We examined hepatocellular carcinoma mortality in relation to coffee consumption and anti-hepatitis C virus (HCV) antibody seropositivity in a nested case–control study involving 96 cases. The multivariate-adjusted odds ratios (95% confidence interval) for daily coffee drinkers vs non-drinkers were 0.49 (0.25–0.96), 0.31 (0.11–0.85), and 0.75 (0.29–1.92) in all cases, in HCV-positive and in HCV-negative individuals, respectively
The effect of interaction between hepatitis C virus and cigarette smoking on the risk of hepatocellular carcinoma
We evaluated the interaction between hepatitis C virus (HCV) and cigarette smoking on death from hepatocellular cancer in The Japan Collaborative Cohort Study. The odds ratio of death from HCC for smoking was 9.60 (1.50–61.35) and 1.71(0.58–5.08) among anti-HCV positive and negative individuals, respectively
The creatine kinase system and pleiotropic effects of creatine
The pleiotropic effects of creatine (Cr) are based mostly on the functions of the enzyme creatine kinase (CK) and its high-energy product phosphocreatine (PCr). Multidisciplinary studies have established molecular, cellular, organ and somatic functions of the CK/PCr system, in particular for cells and tissues with high and intermittent energy fluctuations. These studies include tissue-specific expression and subcellular localization of CK isoforms, high-resolution molecular structures and structure–function relationships, transgenic CK abrogation and reverse genetic approaches. Three energy-related physiological principles emerge, namely that the CK/PCr systems functions as (a) an immediately available temporal energy buffer, (b) a spatial energy buffer or intracellular energy transport system (the CK/PCr energy shuttle or circuit) and (c) a metabolic regulator. The CK/PCr energy shuttle connects sites of ATP production (glycolysis and mitochondrial oxidative phosphorylation) with subcellular sites of ATP utilization (ATPases). Thus, diffusion limitations of ADP and ATP are overcome by PCr/Cr shuttling, as most clearly seen in polar cells such as spermatozoa, retina photoreceptor cells and sensory hair bundles of the inner ear. The CK/PCr system relies on the close exchange of substrates and products between CK isoforms and ATP-generating or -consuming processes. Mitochondrial CK in the mitochondrial outer compartment, for example, is tightly coupled to ATP export via adenine nucleotide transporter or carrier (ANT) and thus ATP-synthesis and respiratory chain activity, releasing PCr into the cytosol. This coupling also reduces formation of reactive oxygen species (ROS) and inhibits mitochondrial permeability transition, an early event in apoptosis. Cr itself may also act as a direct and/or indirect anti-oxidant, while PCr can interact with and protect cellular membranes. Collectively, these factors may well explain the beneficial effects of Cr supplementation. The stimulating effects of Cr for muscle and bone growth and maintenance, and especially in neuroprotection, are now recognized and the first clinical studies are underway. Novel socio-economically relevant applications of Cr supplementation are emerging, e.g. for senior people, intensive care units and dialysis patients, who are notoriously Cr-depleted. Also, Cr will likely be beneficial for the healthy development of premature infants, who after separation from the placenta depend on external Cr. Cr supplementation of pregnant and lactating women, as well as of babies and infants are likely to be of benefit for child development. Last but not least, Cr harbours a global ecological potential as an additive for animal feed, replacing meat- and fish meal for animal (poultry and swine) and fish aqua farming. This may help to alleviate human starvation and at the same time prevent over-fishing of oceans
Modelagem estatística para estimação da população de protozoários ruminais em função da relação volumoso: concentrado na dieta e da presença de aditivos
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