316 research outputs found
Laser ablation-inductively coupled plasma mass spectrometry for the characterization of pigments in prehistoric rock art
Control strategies for DFIG wind turbines under grid fault conditions
The classical control techniques for regulating
the active and reactive power delivery in doubly fed
induction generators (DFIG), for wind power applications,
are normally based on voltage oriented control (VOC)
strategies. Among these algorithms, those that work in a
synchronous reference frame, attached to the magnetic
flux vector, became very popular. In spite of the good
behaviour of such algorithms their performance depends
highly on an accurate detection of the stator flux position,
something that can be critical under unbalanced or
distorted grid voltage conditions. This paper presents a
new VOC strategy able to control the operation of a DFIG
in the ιβ reference frame, with no need of flux position
estimation, something that conducts to a more simple and
robust algorithm. In order to evaluate the advantages of
this new control proposal, namely VOC-RRF, their
performance will be compared with the response obtained
with a classical VOC algorithm by means of
PSCAD/EMTDCÂŽ simulation models.Peer ReviewedPostprint (published version
Control of DFIG-WT under unbalanced grid voltage conditions
The voltage oriented control in the synchronous
reference frame (VOC-SRF) have been extensively used for
controlling wind turbines based on doubly fed induction
generators (DFIG-WTs) through the rotor side converter of a
back to back power processor. Although its performance is fast
and accurate under balanced conditions its behaviour is not
good enough when the voltage of the mains is unbalanced, unless
an independent control for the positive and the negative
sequence is implemented. This paper proposes a new control
system able to control the DFIG-WT under unbalanced
conditions using a simple algorithm, which does not need to be
implemented for both symmetrical components but on the static
ιβ reference frame. The reliability of the presented system will
be tested by means of PSCAD simulations under balanced and
unbalanced grid conditions.Peer ReviewedPostprint (published version
RestauraciĂłn de montes quemados en condiciones mediterrĂĄneas
Wildfires may produce ecosystem damages that would require post-fire mitigation and/or restoration actions. The question is what are the criteria to identify those burned areas that show high degradation risk in order to plan and prioritise restoration projects. To address that question it is necessary to start with the analysis of fire impact, and from that analysis to derive predictive tools for assessing the fragility and regeneration capacity of burned ecosystems. The identification of post-fire degradation mechanisms provides the basis for developing the corresponding specific mitigation/restoration actions. The diagnostic of ecological impact of wildfires together with the established forest management objectives allow deriving mitigation/restoration strategies and the subsequent implementation projects. We present our experience on the evaluation of post-fire ecosystem vulnerability and on the assessment of restoration planning derived from recent and ongoing EC research projects. This includes the development of short-term restoration techniques suited for degraded soils and dry Mediterranean conditions, where fire-induced degradation is complicated with water shortage for regenerating vegetation
Psychotic-like experiences, polygenic risk scores for schizophrenia, and structural properties of the salience, default mode, and central-executive networks in healthy participants from UK Biobank
A Chemical Analog of Curcumin as an Improved Inhibitor of Amyloid Abeta Oligomerization
Amyloid-like plaques are characteristic lesions defining the neuropathology of Alzheimer's disease (AD). The size and density of these plaques are closely associated with cognitive decline. To combat this disease, the few therapies that are available rely on drugs that increase neurotransmission; however, this approach has had limited success as it has simply slowed an imminent decline and failed to target the root cause of AD. Amyloid-like deposits result from aggregation of the Aβ peptide, and thus, reducing amyloid burden by preventing Aβ aggregation represents an attractive approach to improve the therapeutic arsenal for AD. Recent studies have shown that the natural product curcumin is capable of crossing the blood-brain barrier in the CNS in sufficient quantities so as to reduce amyloid plaque burden. Based upon this bioactivity, we hypothesized that curcumin presents molecular features that make it an excellent lead compound for the development of more effective inhibitors of Aβ aggregation. To explore this hypothesis, we screened a library of curcumin analogs and identified structural features that contribute to the anti-oligomerization activity of curcumin and its analogs. First, at least one enone group in the spacer between aryl rings is necessary for measureable anti-Aβ aggregation activity. Second, an unsaturated carbon spacer between aryl rings is essential for inhibitory activity, as none of the saturated carbon spacers showed any margin of improvement over that of native curcumin. Third, methoxyl and hydroxyl substitutions in the meta- and para-positions on the aryl rings appear necessary for some measure of improved inhibitory activity. The best lead inhibitors have either their meta- and para-substituted methoxyl and hydroxyl groups reversed from that of curcumin or methoxyl or hydroxyl groups placed in both positions. The simple substitution of the para-hydroxy group on curcumin with a methoxy substitution improved inhibitor function by 6-7-fold over that measured for curcumin
Curcumin Promotes A-beta Fibrillation and Reduces Neurotoxicity in Transgenic Drosophila
The pathology of Alzheimer's disease (AD) is characterized by the presence of extracellular deposits of misfolded and aggregated amyloid-β (Aβ) peptide and intraneuronal accumulation of tangles comprised of hyperphosphorylated Tau protein. For several years, the natural compound curcumin has been proposed to be a candidate for enhanced clearance of toxic Aβ amyloid. In this study we have studied the potency of feeding curcumin as a drug candidate to alleviate Aβ toxicity in transgenic Drosophila. The longevity as well as the locomotor activity of five different AD model genotypes, measured relative to a control line, showed up to 75% improved lifespan and activity for curcumin fed flies. In contrast to the majority of studies of curcumin effects on amyloid we did not observe any decrease in the amount of Aβ deposition following curcumin treatment. Conformation-dependent spectra from p-FTAA, a luminescent conjugated oligothiophene bound to Aβ deposits in different Drosophila genotypes over time, indicated accelerated pre-fibrillar to fibril conversion of Aβ1â42 in curcumin treated flies. This finding was supported by in vitro fibrillation assays of recombinant Aβ1â42. Our study shows that curcumin promotes amyloid fibril conversion by reducing the pre-fibrillar/oligomeric species of Aβ, resulting in a reduced neurotoxicity in Drosophila
A large scale survey reveals that chromosomal copy-number alterations significantly affect gene modules involved in cancer initiation and progression
Background
Recent observations point towards the existence of a large number of neighborhoods composed of functionally-related gene modules that lie together in the genome. This local component in the distribution of the functionality across chromosomes is probably affecting the own chromosomal architecture by limiting the possibilities in which genes can be arranged and distributed across the genome. As a direct consequence of this fact it is therefore presumable that diseases such as cancer, harboring DNA copy number alterations (CNAs), will have a symptomatology strongly dependent on modules of functionally-related genes rather than on a unique "important" gene.
Methods
We carried out a systematic analysis of more than 140,000 observations of CNAs in cancers and searched by enrichments in gene functional modules associated to high frequencies of loss or gains.
Results
The analysis of CNAs in cancers clearly demonstrates the existence of a significant pattern of loss of gene modules functionally related to cancer initiation and progression along with the amplification of modules of genes related to unspecific defense against xenobiotics (probably chemotherapeutical agents). With the extension of this analysis to an Array-CGH dataset (glioblastomas) from The Cancer Genome Atlas we demonstrate the validity of this approach to investigate the functional impact of CNAs.
Conclusions
The presented results indicate promising clinical and therapeutic implications. Our findings also directly point out to the necessity of adopting a function-centric, rather a gene-centric, view in the understanding of phenotypes or diseases harboring CNAs.Spanish Ministry of Science and Innovation (grant BIO2008-04212)Spanish Ministry of Science and Innovation (grant FIS PI 08/0440)GVA-FEDER (PROMETEO/2010/001)Red TemĂĄtica de InvestigaciĂłn Cooperativa en CĂĄncer (RTICC) (grant RD06/0020/1019)Instituto de Salud Carlos III (ISCIII)Spanish Ministry of Science and InnovationSpanish Ministry of Health (FI06/00027
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Intracranial and subcortical volumes in adolescents with earlyâonset psychosis: A multisite megaâanalysis from the ENIGMA consortium
Earlyâonset psychosis disorders are serious mental disorders arising before the age of 18âyears. Here, we investigate the largest neuroimaging dataset, to date, of patients with earlyâonset psychosis and healthy controls for differences in intracranial and subcortical brain volumes. The sample included 263 patients with earlyâonset psychosis (mean age: 16.4âÂąâ1.4âyears, mean illness duration: 1.5âÂąâ1.4âyears, 39.2% female) and 359 healthy controls (mean age: 15.9âÂąâ1.7âyears, 45.4% female) with magnetic resonance imaging data, pooled from 11 clinical cohorts. Patients were diagnosed with earlyâonset schizophrenia (n = 183), affective psychosis (n = 39), or other psychotic disorders (n = 41). We used linear mixedâeffects models to investigate differences in intracranial and subcortical volumes across the patient sample, diagnostic subgroup and antipsychotic medication, relative to controls. We observed significantly lower intracranial (Cohen's d = â0.39) and hippocampal (d = â0.25) volumes, and higher caudate (d = 0.25) and pallidum (d = 0.24) volumes in patients relative to controls. Intracranial volume was lower in both earlyâonset schizophrenia (d = â0.34) and affective psychosis (d = â0.42), and earlyâonset schizophrenia showed lower hippocampal (d = â0.24) and higher pallidum (d = 0.29) volumes. Patients who were currently treated with antipsychotic medication (n = 193) had significantly lower intracranial volume (d = â0.42). The findings demonstrate a similar pattern of brain alterations in earlyâonset psychosis as previously reported in adult psychosis, but with notably low intracranial volume. The low intracranial volume suggests disrupted neurodevelopment in adolescent earlyâonset psychosis
arrayMap: A Reference Resource for Genomic Copy Number Imbalances in Human Malignancies
Background: The delineation of genomic copy number abnormalities (CNAs) from
cancer samples has been instrumental for identification of tumor suppressor
genes and oncogenes and proven useful for clinical marker detection. An
increasing number of projects have mapped CNAs using high-resolution microarray
based techniques. So far, no single resource does provide a global collection
of readily accessible oncoge- nomic array data.
Methodology/Principal Findings: We here present arrayMap, a curated reference
database and bioinformatics resource targeting copy number profiling data in
human cancer. The arrayMap database provides a platform for meta-analysis and
systems level data integration of high-resolution oncogenomic CNA data. To
date, the resource incorporates more than 40,000 arrays in 224 cancer types
extracted from several resources, including the NCBI's Gene Expression Omnibus
(GEO), EBIs ArrayExpress (AE), The Cancer Genome Atlas (TCGA), publication
supplements and direct submissions. For the majority of the included datasets,
probe level and integrated visualization facilitate gene level and genome wide
data re- view. Results from multi-case selections can be connected to
downstream data analysis and visualization tools.
Conclusions/Significance: To our knowledge, currently no data source provides
an extensive collection of high resolution oncogenomic CNA data which readily
could be used for genomic feature mining, across a representative range of
cancer entities. arrayMap represents our effort for providing a long term
platform for oncogenomic CNA data independent of specific platform
considerations or specific project dependence. The online database can be
accessed at http://www.arraymap.org.Comment: 17 pages, 5 inline figures, 3 tables, supplementary figures/tables
split into 4 PDF files; manuscript submitted to PLoS ON
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