249 research outputs found
Improved Nearside-Farside Decomposition of Elastic Scattering Amplitudes
A simple technique is described, that provides improved nearside-farside (NF)
decompositions of elastic scattering amplitudes. The technique, involving the
resummation of a Legendre partial wave series, reduces the importance of
unphysical contributions to NF subamplitudes, which can arise in more
conventional NF decompositions. Applications are made to a strong absorption
model and to a O + C optical potential at
MeV.Comment: 5 pages, 2 figure
Activation of Liver X Receptors and Peroxisome Proliferator-Activated Receptors by Lipid Extracts of Brown Seaweeds:A Potential Application in Alzheimer’s Disease?
The nuclear liver X receptors (LXRα/β) and peroxisome proliferator-activated receptors (PPARα/γ) are involved in the regulation of multiple biological processes, including lipid metabolism and inflammation. The activation of these receptors has been found to have neuroprotective effects, making them interesting therapeutic targets for neurodegenerative disorders such as Alzheimer's Disease (AD). The Asian brown seaweed Sargassum fusiforme contains both LXR-activating (oxy)phytosterols and PPAR-activating fatty acids. We have previously shown that dietary supplementation with lipid extracts of Sargassum fusiforme prevents disease progression in a mouse model of AD, without inducing adverse effects associated with synthetic pan-LXR agonists. We now determined the LXRα/β- and PPARα/γ-activating capacity of lipid extracts of six European brown seaweed species ( Alaria esculenta, Ascophyllum nodosum, Fucus vesiculosus, Himanthalia elongata, Saccharina latissima, and Sargassum muticum) and the Asian seaweed Sargassum fusiforme using a dual luciferase reporter assay. We analyzed the sterol and fatty acid profiles of the extracts by GC-MS and UPLC MS/MS, respectively, and determined their effects on the expression of LXR and PPAR target genes in several cell lines using quantitative PCR. All extracts were found to activate LXRs, with the Himanthalia elongata extract showing the most pronounced efficacy, comparable to Sargassum fusiforme, for LXR activation and transcriptional regulation of LXR-target genes. Extracts of Alaria esculenta, Fucus vesiculosus, and Saccharina latissima showed the highest capacity to activate PPARα, while extracts of Alaria esculenta, Ascophyllum nodosum, Fucus vesiculosus, and Sargassum muticum showed the highest capacity to activate PPARγ, comparable to Sargassum fusiforme extract. In CCF-STTG1 astrocytoma cells, all extracts induced expression of cholesterol efflux genes ( ABCG1, ABCA1, and APOE) and suppressed expression of cholesterol and fatty acid synthesis genes ( DHCR7, DHCR24, HMGCR and SREBF2, and SREBF1, ACACA, SCD1 and FASN, respectively). Our data show that lipophilic fractions of European brown seaweeds activate LXRs and PPARs and thereby modulate lipid metabolism. These results support the potential of brown seaweeds in the prevention and/or treatment of neurodegenerative diseases and possibly cardiometabolic and inflammatory diseases via concurrent activation of LXRs and PPARs. </p
Simultaneous and independent detection of C9ORF72 alleles with low and high number of GGGGCC repeats using an optimised protocol of Southern blot hybridisation
Background
Sizing of GGGGCC hexanucleotide repeat expansions within the C9ORF72 locus, which account for approximately 10% of all amyotrophic lateral sclerosis (ALS) cases, is urgently required to answer fundamental questions about mechanisms of pathogenesis in this important genetic variant. Currently employed PCR protocols are limited to discrimination between the presence and absence of a modified allele with more than 30 copies of the repeat, while Southern hybridisation-based methods are confounded by the somatic heterogeneity commonly present in blood samples, which might cause false-negative or ambiguous results.
Results
We describe an optimised Southern hybridisation-based protocol that allows confident detection of the presence of a C9ORF72 repeat expansion alongside independent assessment of its heterogeneity and the number of repeat units. The protocol can be used with either a radiolabeled or non-radiolabeled probe. Using this method we have successfully sized the C9ORF72 repeat expansion in lymphoblastoid cells, peripheral blood, and post-mortem central nervous system (CNS) tissue from ALS patients. It was also possible to confidently demonstrate the presence of repeat expansion, although of different magnitude, in both C9ORF72 alleles of the genome of one patient.
Conclusions
The suggested protocol has sufficient advantages to warrant adoption as a standard for Southern blot hybridisation analysis of GGGGCC repeat expansions in the C9ORF72 locu
A straw drift chamber spectrometer for studies of rare kaon decays
We describe the design, construction, readout, tests, and performance of
planar drift chambers, based on 5 mm diameter copperized Mylar and Kapton
straws, used in an experimental search for rare kaon decays. The experiment
took place in the high-intensity neutral beam at the Alternating Gradient
Synchrotron of Brookhaven National Laboratory, using a neutral beam stop, two
analyzing dipoles, and redundant particle identification to remove backgrounds
Transcendence over Diversity: black women in the academy
Universities, like many major public institutions have embraced the notion of ‘diversity’ virtually uncritically- it is seen as a moral ‘good in itself’. But what happens to those who come to represent ‘diversity’- the black and minority ethnic groups targeted to increase the institutions thirst for global markets and aversion to accusations of institutional racism? Drawing on existing literature which analyses the process of marginalization in higher education, this paper explores the individual costs to black and female academic staff regardless of the discourse on diversity. However despite the exclusion of staff, black and minority ethnic women are also entering higher education in relatively large numbers as students. Such ‘grassroots’ educational urgency transcends the dominant discourse on diversity and challenges presumptions inherent in top down initiatives such as ‘widening participation’. Such a collective movement from the bottom up shows the importance of understanding black female agency when unpacking the complex dynamics of gendered and racialised exclusion. Black women’s desire for education and learning makes possible a reclaiming of higher education from creeping instrumentalism and reinstates it as a radical site of resistance and refutation
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Evaluation of Scintillator Detection Materials for Application within Airborne Environmental Radiation Monitoring
In response to the Fukushima Daiichi Nuclear Power Plant accident, there has occurred the unabated growth in the number of airborne platforms developed to perform radiation mapping—each utilising various designs of a low-altitude uncrewed aerial vehicle. Alongside the associated advancements in the airborne system transporting the radiation detection payload, from the earliest radiological analyses performed using gas-filled Geiger-Muller tube detectors, modern radiation detection and mapping platforms are now based near-exclusively on solid-state scintillator detectors. With numerous varieties of such light-emitting crystalline materials now in existence, this combined desk and computational modelling study sought to evaluate the best-available detector material compatible with the requirements for low-altitude autonomous radiation detection, localisation and subsequent high spatial-resolution mapping of both naturally occurring and anthropogenically-derived radionuclides. The ideal geometry of such detector materials is also evaluated. While NaI and CsI (both elementally doped) are (and will likely remain) the mainstays of radiation detection, LaBr3 scintillation detectors were determined to possess not only a greater sensitivity to incident gamma-ray radiation, but also a far superior spectral (energy) resolution over existing and other potentially deployable detector materials. Combined with their current competitive cost, an array of three such composition cylindrical detectors were determined to provide the best means of detecting and discriminating the various incident gamma-rays
Stomatal responses of Eucalyptus species to elevated CO2 concentration and drought stress
Five species of Eucalyptus (E. grandis, E. urophylla, E. camaldulensis, E. torelliana, and E. phaeotrica), among the ten species most commonly used in large scale plantations, were selected for studies on the effects of elevated CO2 concentration [CO2] and drought stress on stomatal responses of 2.5-month old seedlings. The first three species belong to the subgenus Smphyomyrtus, whereas the fourth species belongs to the subgenus Corymbia and E. phaeotrica is from the subgenus Monocalyptus. Seedlings were grown in four pairs of open-top chambers, arranged to have 2 plants of each species in each chamber, with four replications in each of two CO2 concentrations: 350 ± 30 mumol mol-1 and 700 ± 30 mumol mol-1. After 100 days in the chambers, a series of gas exchange measurements were made. Half the plants in each chamber, one plant per species per chamber, were drought-stressed by withholding irrigation, while the remaining plants continued to be watered daily. Drought stress decreased stomatal conductance, photosynthesis and transpiration rates in all the species. The effect of drought stress on stomatal closure was similar in both [CO2]. The positive effects of elevated [CO2] on photosynthesis and water use efficiency were maintained longer during the stress period than under well-watered conditions. The photosynthetic rate of E. phaeotrica was higher even in the fourth day of the drought stress. Drought stress increased photoinhibition of photosynthesis, as measured by chlorophyll fluorescence, which varied among the species, as well as in relation to [CO2]. The results are in agreement with observed differences in stomatal responses between some eucalyptus species of the subgenera Symphyomyrtus and Monocalyptus
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