2,208 research outputs found

    Forecasting confined spatiotemporal chaos with genetic algorithms

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    A technique to forecast spatiotemporal time series is presented. it uses a Proper Ortogonal or Karhunen-Lo\`{e}ve Decomposition to encode large spatiotemporal data sets in a few time-series, and Genetic Algorithms to efficiently extract dynamical rules from the data. The method works very well for confined systems displaying spatiotemporal chaos, as exemplified here by forecasting the evolution of the onedimensional complex Ginzburg-Landau equation in a finite domain.Comment: 4 pages, 5 figure

    Geotechnical and geomechanical characterization of the fault gouge of the Alhama de Murcia active fault, SE Spain

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    Here we present the results of the mechanical and mineralogical study of the fault rock of the Alhama de Murcia fault. This fault is one of the most active faults in the Iberian Peninsula. It shows segments partially formed by exhumed fine grained fault rocks (fault gouge FG) with a thickness of more than 50 m developed mainly in a brittle regime. Several strength and strain tests have been carried out, both in-situ and in laboratory, considering different stress orientations in relation to the tectonic fabric. Undisturbed samples encountered from two fault observatory boreholes drilled near Lorca, (FAM-1 and FAMSIS-IGN, of 174 and 40 m depth, respectively) has been used for the laboratory tests. The FG shows a hard soil and soft rock like mechanical behavior with uniaxial compressive strength 1.19) for planes unfavourably oriente

    New compound sets identified from high throughput phenotypic screening against three kinetoplastid parasites:an open resource

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    Using whole-cell phenotypic assays, the GlaxoSmithKline high-throughput screening (HTS) diversity set of 1.8 million compounds was screened against the three kinetoplastids most relevant to human disease, i.e. Leishmania donovani, Trypanosoma cruzi and Trypanosoma brucei. Secondary confirmatory and orthogonal intracellular anti-parasiticidal assays were conducted, and the potential for non-specific cytotoxicity determined. Hit compounds were chemically clustered and triaged for desirable physicochemical properties. The hypothetical biological target space covered by these diversity sets was investigated through bioinformatics methodologies. Consequently, three anti-kinetoplastid chemical boxes of ~200 compounds each were assembled. Functional analyses of these compounds suggest a wide array of potential modes of action against kinetoplastid kinases, proteases and cytochromes as well as potential host–pathogen targets. This is the first published parallel high throughput screening of a pharma compound collection against kinetoplastids. The compound sets are provided as an open resource for future lead discovery programs, and to address important research questions.The support and funding of Tres Cantos Open Lab Foundation is gratefully acknowledgedPeer reviewe

    Effect of serum phosphate on parathyroid hormone secretion during hemodialysis

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    Effect of serum phosphate on parathyroid hormone secretion during hemodialysis.BackgroundRecent studies have demonstrated that a high concentration of phosphate directly stimulates parathyroid hormone (PTH) secretion. High serum levels of phosphate are usually observed in patients with end-stage renal disease. The aim of the present study was to evaluate whether serum phosphate concentration had an acute effect on PTH secretion in hemodialysis patients. The levels of serum phosphate were manipulated during the hemodialysis session by using a phosphate free dialysate or a dialysate with a high content of phosphate.MethodsTen stable hemodialysis patients with PTH values above 300 pg/ml were included in the study. A PTH-calcium curve was obtained during both high phosphate and phosphate free hemodialysis.ResultsThe serum phosphate concentration remained high (2.17 ± 0.18mM) throughout the high phosphate hemodialysis and decreased progressively to normal levels (1.02 ± 0.06mM) during the phosphate free hemodialysis. The serum PTH levels at maximal inhibition by hypercalcemia (minimal PTH) were greater during the high phosphate than the phosphate free hemodialysis (413 ± 79 vs. 318 ± 76 pg/ml, P < 0.003). In all patients the values of minimum PTH were greater during the high phosphorus than the phosphorus free hemodialysis. The values of maximally stimulated PTH during hypocalcemia and the set point of the PTH-calcium curve were similar during the high phosphate and the phosphate free hemodialysis.ConclusionThe maintenance of high serum phosphorus levels during hemodialysis prevented, in part, the inhibition of PTH secretion by calcium, which strongly suggests that in hemodialysis patients high serum phosphate contributes directly to the elevation of PTH levels despite normal or high serum calcium concentration

    Characterization of Glutamatergic Phenotypes in Hybrid Septal Neuroblastoma (SN56) cells

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    Septal Neuroblastoma (SN 56) cells are hybrid cells made through cell fusions between quiescent medial septum neurons (cholinergic) and tumoral neuroblastoma cells. Cholinergic cells synthesize and release the neurotransmitter acetylcholine. Preliminary studies in our laboratory revealed that SN 56 neurons also express the vesicular glutamate transporter type 1 (VGluT1), a protein that is normally produced by glutamatergic neurons. This discovery prompted us to hypothesize that SN 56 neurons may also co-express a glutamatergic phenotype which is important because glutamatergic neurons have been associated to the pathogenesis of neurological disorders such as Alzheimer’s disease. To assess whether SN 56 neurons express in fact both phenotypes, we conducted experiments in differentiated and no differentiated SN 56 cell, to confirm the expression of glutamatergic phenotype, by qPCR, western blotting and Immunocytochemistry assay. The cells are cultured in an incubator gassed with 5% CO2 at 37°C. After differentiation for 3-5 days with cAMP and retinoic acid, SN 56 cells were prepared for qPCR, western blotting and immunocytochemistry. Cells were separated by each experiment, primary antibodies or primers against NMDA glutamate receptor subunit NR2B, VG luT1 and vesicular cholinergic transport (ChAT) how positive control were used to confirm our hypothesis,. Expression of these markers will indicate a glutamatergic phenotype. After secondary detection with appropriate fluorescently-labeled antibodies we confirmed that differentiated SN 56 neurons express glutamate NR2B receptor subtype and the VGluT1 transporter in both post-synaptic and presynaptic structures respectively. Hence, these findings support our hypothesis that SN 56 neurons can co-express both cholinergic and glutamatergic phenotype

    Simple models for scaling in phylogenetic trees

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    Many processes and models --in biological, physical, social, and other contexts-- produce trees whose depth scales logarithmically with the number of leaves. Phylogenetic trees, describing the evolutionary relationships between biological species, are examples of trees for which such scaling is not observed. With this motivation, we analyze numerically two branching models leading to non-logarithmic scaling of the depth with the number of leaves. For Ford's alpha model, although a power-law scaling of the depth with tree size was established analytically, our numerical results illustrate that the asymptotic regime is approached only at very large tree sizes. We introduce here a new model, the activity model, showing analytically and numerically that it also displays a power-law scaling of the depth with tree size at a critical parameter value.Comment: 7 pages, 4 figures. A new figure, with example trees, has been added. To appear in Int. J. Bifurcation and Chao
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