1,283 research outputs found
Niemann-Pick Type C Disease Reveals a Link between Lysosomal Cholesterol and PtdIns(4,5)P2 That Regulates Neuronal Excitability.
There is increasing evidence that the lysosome is involved in the pathogenesis of a variety of neurodegenerative disorders. Thus, mechanisms that link lysosome dysfunction to the disruption of neuronal homeostasis offer opportunities to understand the molecular underpinnings of neurodegeneration and potentially identify specific therapeutic targets. Here, using a monogenic neurodegenerative disorder, NPC1 disease, we demonstrate that reduced cholesterol efflux from lysosomes aberrantly modifies neuronal firing patterns. The molecular mechanism linking alterations in lysosomal cholesterol egress to intrinsic tuning of neuronal excitability is a transcriptionally mediated upregulation of the ABCA1 transporter, whose PtdIns(4,5)P2-floppase activity decreases plasma membrane PtdIns(4,5)P2. The consequence of reduced PtdIns(4,5)P2 is a parallel decrease in a key regulator of neuronal excitability, the voltage-gated KCNQ2/3 potassium channel, which leads to hyperexcitability in NPC1 disease neurons. Thus, cholesterol efflux from lysosomes regulates PtdIns(4,5)P2 to shape the electrical and functional identity of the plasma membrane of neurons in health and disease
Hydrogen vs. Battery in the long-term operation. A comparative between energy management strategies for hybrid renewable microgrids
The growth of the world’s energy demand over recent decades in relation to energy intensity and demography is clear. At the same time, the use of renewable energy sources is pursued to address decarbonization targets, but the stochasticity of renewable energy systems produces an increasing need for management systems to supply such energy volume while guaranteeing, at the same time, the security and reliability of the microgrids. Locally distributed energy storage systems (ESS) may provide the capacity to temporarily decouple production and demand. In this sense, the most implemented ESS in local energy districts are small–medium-scale electrochemical batteries. However, hydrogen systems are viable for storing larger energy quantities thanks to its intrinsic high mass-energy density. To match generation, demand and storage, energy management systems (EMSs) become crucial. This paper compares two strategies for an energy management system based on hydrogen-priority vs. battery-priority for the operation of a hybrid renewable microgrid. The overall performance of the two mentioned strategies is compared in the long-term operation via a set of evaluation parameters defined by the unmet load, storage efficiency, operating hours and cumulative energy. The results show that the hydrogen-priority strategy allows the microgrid to be led towards island operation because it saves a higher amount of energy, while the battery-priority strategy reduces the energy efficiency in the storage round trip. The main contribution of this work lies in the demonstration that conventional EMS for microgrids’ operation based on battery-priority strategy should turn into hydrogen-priority to keep the reliability and independence of the microgrid in the long-term operation
Searching for tidal tails around Centauri using RR Lyrae Stars
We present a survey for RR Lyrae stars in an area of 50 deg around the
globular cluster Centauri, aimed to detect debris material from the
alleged progenitor galaxy of the cluster. We detected 48 RR Lyrae stars of
which only 11 have been previously reported. Ten among the eleven previously
known stars were found inside the tidal radius of the cluster. The rest were
located outside the tidal radius up to distances of degrees from the
center of the cluster. Several of those stars are located at distances similar
to that of Centauri. We investigated the probability that those stars
may have been stripped off the cluster by studying their properties (mean
periods), calculating the expected halo/thick disk population of RR Lyrae stars
in this part of the sky, analyzing the radial velocity of a sub-sample of the
RR Lyrae stars, and finally, studying the probable orbits of this sub-sample
around the Galaxy. None of these investigations support the scenario that there
is significant tidal debris around Centauri, confirming previous
studies in the region. It is puzzling that tidal debris have been found
elsewhere but not near the cluster itself.Comment: 11 pages, 11 figures, Accepte
Formation of Flavanol-aldehyde Adducts in Barrel-aged White Wine - Possible Contribution of These Products to Colour
[EN] This paper describes the formation and diversity of new compounds resulting from the polymerisation of furanic and
phenolic flavanol-aldehydes with HPLC¿DAD and LC¿ES/MS analysis. Polymerisation, resulting from nucleophilic
reactions, formed dimers, trimers, soluble and insoluble polymers. Reactions in hydroalcoholic solution with pure
aldehydes (phenolic and furanic) and flavanols (catechin) were studied. The study was repeated with different
aldehydes in white wine. This research focused particularly on the colour properties of the released products and their
potential impact on the colour of white wine. Some products were purified and isolated; these were mainly catechinfurfuraldehyde,
catechin-methyl-5-furfuraldehyde, catechin-hydroxymethyl-furfuraldehyde, catechin-vanillin, and
catechin-syringaldehyde dimers. The most powerful coloured products resulted from furanic aldehydes. Over the
course of the experiment, the reaction produced dimers, trimers and oligomers. After 50 to 60 days, the colour of the
solution was mainly due to soluble polymeric forms. In addition, the role of SO2
, generally used during vinification
and ageing, was studied. The influence of SO2 on the kinetics of the reaction was limited.Vivas, N.; Nonier, MFB.; Absalon, C.; Lizama Abad, V.; Jamet, F.; De Gaulejac, NV.; Vitry, C.... (2008). Formation of Flavanol-aldehyde Adducts in Barrel-aged White Wine - Possible Contribution of These Products to Colour. South African journal of enology and viticulture. 29(2):98-108. http://hdl.handle.net/10251/105310S9810829
Variable Stars in Local Group Galaxies. IV. RR Lyrae stars in the central regions of the low-density galaxy Crater II
We present a search and analysis of variable stars in the recently discovered
Crater~II dwarf galaxy. Based on , , data collected with the Isaac
Newton Telescope (FoV0.44 square degrees) we detected 37 variable stars,
of which 34 are bone-fide RR Lyrae stars of Crater~II (28 RRab, 4 RRc, 2 RRd).
We applied the metal-independent (, ) Period--Wesenheit relation and
derived a true distance modulus ( = 20.300.08 mag (=0.16
mag). Individual metallicities for RR Lyrae stars were derived by inversion of
the predicted -band Period-Luminosity relation. We find a mean metallicity
of [Fe/H]=-1.64 and a standard deviation of =0.21 dex,
compatible with either negligible or vanishing intrinsic metallicity
dispersion. The analysis of the Colour-Magnitude Diagram reveals a stark
paucity of blue horizontal branch stars, at odds with other Galactic dwarfs,
and globular clusters with similar metal abundances.Comment: 14 pages, 8 figures, accepted for publications on MNRAS. Time series
photometry is available in the manuscript source ta
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