1,043 research outputs found
Five year prognosis in patients with angina identified in primary care : incident cohort study
Peer reviewedPublisher PD
Laser frequency comb techniques for precise astronomical spectroscopy
Precise astronomical spectroscopic analyses routinely assume that individual
pixels in charge-coupled devices (CCDs) have uniform sensitivity to photons.
Intra-pixel sensitivity (IPS) variations may already cause small systematic
errors in, for example, studies of extra-solar planets via stellar radial
velocities and cosmological variability in fundamental constants via quasar
spectroscopy, but future experiments requiring velocity precisions approaching
~1 cm/s will be more strongly affected. Laser frequency combs have been shown
to provide highly precise wavelength calibration for astronomical
spectrographs, but here we show that they can also be used to measure IPS
variations in astronomical CCDs in situ. We successfully tested a laser
frequency comb system on the Ultra-High Resolution Facility spectrograph at the
Anglo-Australian Telescope. By modelling the 2-dimensional comb signal recorded
in a single CCD exposure, we find that the average IPS deviates by <8 per cent
if it is assumed to vary symmetrically about the pixel centre. We also
demonstrate that series of comb exposures with absolutely known offsets between
them can yield tighter constraints on symmetric IPS variations from ~100
pixels. We discuss measurement of asymmetric IPS variations and absolute
wavelength calibration of astronomical spectrographs and CCDs using frequency
combs.Comment: 11 pages, 7 figures. Accepted for publication in MNRA
Effect of Polyphenol Supplementation on Memory Functioning in Overweight and Obese Adults: A Systematic Review and Meta-Analysis
Negative health consequences of obesity include impaired neuronal functioning and celldeath, thus bringing the risk of impaired cognitive functioning. Antioxidant properties of polyphenolsoffer a possible intervention for overweight people, but evidence for their effectiveness in supportingcognitive functioning is mixed. This review examined evidence from randomized controlledtrials concerning the effect of polyphenols on tasks requiring either immediate or delayed retrievalof learned information, respectively, thus controlling for differences in cognitive processes and relatedneural substrates supporting respective task demands. Searches of the PubMed/Medline,PsycInfo, and Scopus databases identified 24 relevant primary studies with N = 2336 participantshaving a BMI â„ 25.0 kg/m2. The participantsâ mean age for the 24 studies exceeded 60 years. Respectivemeta-analyses produced a significant summary effect for immediate retrieval but not for delayedretrieval. The present findings support a potential positive effect of chronic supplementationwith polyphenols, most notably flavonoids, on immediate retrieval in participants aged over 60years with obesity being a risk factor for cognitive impairment. We recommend further investigationof this potential positive effect in participants with such risk factors. Future research on all populationsshould report the phenolic content of the supplementation administered and be specific regardingthe cognitive processes tested
The Spatial Extent of (U)LIRGs in the Mid-Infrared. II. Feature Emission
We present results from the second part of our analysis of the extended
mid-infrared (MIR) emission of the Great Observatories All-Sky LIRG Survey
(GOALS) sample based on 5-14 micron low-resolution spectra obtained with the
IRS on Spitzer. We calculate the fraction of extended emission as a function of
wavelength for all galaxies in the sample, FEE_lambda, and spatially separate
the MIR spectrum of galaxies into their nuclear and extended components.
We find that the [NeII] emission line is as compact as the hot dust MIR
continuum, while the polycyclic aromatic hydrocarbon (PAH) emission is more
extended. The 6.2 and 7.7 micron PAH emission is more compact than that of the
11.3 micron PAH, which is consistent with the formers being enhanced in a more
ionized medium. The presence of an AGN or a powerful nuclear starburst
increases the compactness of the hot dust MIR continuum, but has a negligible
effect on the spatial extent of the PAH emission on kpc-scales. Globally, the
spectra of the extended emission component are homogeneous for all galaxies in
GOALS. This suggests that the physical properties of star formation taking
place at distances farther than 1.5 kpc from the nuclei of (U)LIRGs are very
similar, resembling local star-forming galaxies with L_IR < 10^11 Lsun, as well
as star formation-dominated ULIRGs at z~2. In contrast, the MIR spectra of the
nuclear component of local (U)LIRGs are very diverse. This implies that the
observed variety of their integrated MIR properties arise, on average, only
from the processes that are taking place in their cores.Comment: 16 pages, 7 figures, accepted for publication in Ap
Assessment of folate receptor-ÎČ expression in human neoplastic tissues
Over-expression of folate receptor alpha on cancer cells has been frequently exploited for delivery of folate-targeted imaging and therapeutic agents to tumors. Because limited information exists on expression of the beta isoform of the folate receptor in human cancers (FR-ÎČ), we have evaluated the immunohistochemical staining pattern of FR-ÎČ in 992 tumor sections from 20 different human cancer types using a new anti-human FR-ÎČ monoclonal antibody. FR-ÎČ expression was shown to be more pronounced in cells within the stroma, primarily macrophages and macrophage-like cells than cancer cells in every cancer type studied. Moreover, FR-ÎČ expression in both cancer and stromal cells was found to be statistically more prominent in females than males. A significant positive correlation was also observed between FR-ÎČ expression on stromal cells and both the stage of the cancer and the presence of lymph node metastases. Based on these data we conclude FR-ÎČ may constitute a good target for specific delivery of therapeutic agents to activated macrophages and that accumulation of FR-ÎČ positive macrophages in the stroma could serve as a useful indicator of a tumor's metastatic potential
Five-Year Prognosis in an Incident Cohort of People Presenting with Acute Myocardial Infarction
Peer reviewedPublisher PD
L-Arginine Is Essential for Pancreatic b-Cell Functional Integrity, Metabolism and Defense From Inflammatory Challenge
In this work, our aim was to determine whether L-arginine (a known insulinotropic amino acid) can promote a shift of b-cell intermediary metabolism favoring glutathione (GSH) and glutathione disulfide (GSSG) antioxidant responses, stimulusâsecretion coupling and functional integrity. Clonal BRIN-BD11 b-cells and mouse islets were cultured for 24 h at various L-arginine concentrations (0â1.15 mmol/l) in the absence or presence of a proinflammatory cytokine cocktail (interleukin 1b, tumour necrosis factor a and interferon g). Cells were assessed for viability, insulin secretion, GSH, GSSG, glutamate, nitric oxide (NO), superoxide, urea, lactate and for the consumption of glucose and glutamine. Protein levels of NO synthase-2, AMP-activated protein kinase (AMPK) and the heat shock protein 72 (HSP72) were also evaluated. We found that L-arginine at 1.15 mmol/l attenuated the loss of b-cell viability observed in the presence of proinflammatory cytokines. L-Arginine increased total cellular GSH and glutamate levels but reduced the GSSG/GSH ratio and glutamate release. The amino acid stimulated glucose consumption in the presence of cytokines while also stimulating AMPK phosphorylation and HSP72 expression. Proinflammatory cytokines reduced, by at least 50%, chronic (24 h) insulin secretion, an effect partially attenuated by L-arginine. Acute insulin secretion was robustly stimulated by L-arginine but this effect was abolished in the presence of cytokines. We conclude that L-arginine can stimulate b-cell insulin secretion, antioxidant and protective responses, enabling increased functional integrity of b-cells and islets in the presence of proinflammatory cytokines. Glucose consumption and intermediary metabolism were increased by L-arginine. These results highlight the importance of L-arginine availability for b-cells during inflammatory challeng
Quiescience as a mechanism for cyclical hypoxia and acidosis
Tumour tissue characteristically experiences fluctuations in substrate supply. This unstable microenvironment drives constitutive metabolic changes within cellular populations and, ultimately, leads to a more aggressive phenotype. Previously, variations in substrate levels were assumed to occur through oscillations in the hĂŠmodynamics of nearby and distant blood vessels. In this paper we examine an alternative hypothesis, that cycles of metabolite concentrations are also driven by cycles of cellular quiescence and proliferation. Using a mathematical modelling approach, we show that the interdependence between cell cycle and the microenvironment will induce typical cycles with the period of order hours in tumour acidity and oxygenation. As a corollary, this means that the standard assumption of metabolites entering diffusive equilibrium around the tumour is not valid; instead temporal dynamics must be considered
Constraining fundamental constants of physics with quasar absorption line systems
We summarize the attempts by our group and others to derive constraints on
variations of fundamental constants over cosmic time using quasar absorption
lines. Most upper limits reside in the range 0.5-1.5x10-5 at the 3sigma level
over a redshift range of approximately 0.5-2.5 for the fine-structure constant,
alpha, the proton-to-electron mass ratio, mu, and a combination of the proton
gyromagnetic factor and the two previous constants, gp(alpha^2/mu)^nu, for only
one claimed variation of alpha. It is therefore very important to perform new
measurements to improve the sensitivity of the numerous methods to at least
<0.1x10-5 which should be possible in the next few years. Future
instrumentations on ELTs in the optical and/or ALMA, EVLA and SKA pathfinders
in the radio will undoutedly boost this field by allowing to reach much better
signal-to-noise ratios at higher spectral resolution and to perform
measurements on molecules in the ISM of high redshift galaxies.Comment: 11 pages, 3 figure
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