Solvable Lie algebras are not that hypo

We study a type of left-invariant structure on Lie groups, or equivalently on Lie algebras. We introduce obstructions to the existence of a hypo structure, namely the 5-dimensional geometry of hypersurfaces in manifolds with holonomy SU(3). The choice of a splitting g^*=V_1 + V_2, and the vanishing of certain associated cohomology groups, determine a first obstruction. We also construct necessary conditions for the existence of a hypo structure with a fixed almost-contact form. For non-unimodular Lie algebras, we derive an obstruction to the existence of a hypo structure, with no choice involved. We apply these methods to classify solvable Lie algebras that admit a hypo structure.Comment: 21 pages; v2: presentation improved, typos corrected, notational conflicts eliminated. To appear in Transformation Group

Acid mine drainage in semi-arid regions: the extent of the problem in the waters of reservoirs in the Iberian Pyrite Belt (SW Spain)

There are many reservoirs in the Iberian Pyrite Belt (IPB), SW Spain, which receive contributions from watercourses affected by acid mine drainage processes, characterised by low pH values and high concentrations of heavy metals and sulphates. When they reach the reservoirs, the waters increase its pH, which will cause most of the metal load carried by the mining channel to precipitate into the reservoir itself and accumulate on its floor. The silting of reservoirs is an environmental problem which can affect the loss of storage capacity, their general functioning and aquatic ecosystems. A study of these is vital to allow both preventative and corrective measures to be established. Climatic conditions are the most significant external controlling factors in terms of the degree and type of mining pollution. The study area presents characteristics typical of the semi-arid Mediterranean climate, with annual precipitation of around 630 mm/year; moderate temperatures with average annual values of 17.1 W C and a temperature range of 50 W C. The aim of this study is to carry out a physical–chemical characterization of the waters where they enter the reservoirs located in the IPB over the course of a hydrological year and to establish possible interdependencies between the various parameters.Financial support for this research was provided by DGCICYT National Plan, project no. CGL2010-21268-C02-01.info:eu-repo/semantics/publishedVersio

Detection of optical emission from the supernova remnant G7.7–3.7

The work of VD is supported by a grant from NWO graduate programme/GRAPPA-PhD programme. VD also acknowledges support from the LKBF, subsidy no. 19.2.027. JVHS acknowledges support from STFC grant ST/R000824/1. PZ acknowledges the support from the NWO Veni Fellowship, grant no. 639.041.647 and NSFC grant 11590781. SA thanks the support under the grant 5077 financed by IAASARS/NOA. AdB thanks the support from the Spanish Government Ministerio de Ciencia e Innovación through grants PGC-2018-091, 3741-B-C22, and SEV 2015-0548, from the Canarian Agency for Research, Innovation and Information Society (ACIISI) of the Canary Islands Government, and from the European Regional Development Fund (ERDF), under grant with reference ProID2017010115.We present the first optical study of the supernova remnant (SNR) G7.7–3.7, with the aim of determining its evolutionary phase since it has been suggested to be the remnant of SN 386 AD. We obtained narrow-band images in the filters H α + [N ii], H β, [O iii], [S ii] that revealed faint optical emission in the southern region of the SNR consisting of two filaments elongated in the east–west direction aligned with the X-ray emitting region of the remnant. The filaments were seen in H α + [N ii], [O iii] images and marginally in the [S ii] images, with a non-detection in H β. Long-slit spectroscopy of the three regions along one filament revealed large ratios of [S ii]/H α = (1.6–2.5), consistent with that expected for a shock-heated SNR. The [S ii] doublet ratio observed in two of the regions implies an upper limit for the electron density of the gas, with estimates falling below 400 cm−3 and 600 cm−3 in the respective areas. We discuss potential physical mechanisms that formed the observed optical filaments and we suggest that most likely they resulted by a collision of the SNR with a dense circumstellar shell lying at the southern region of the remnant.Publisher PDFPeer reviewe

Detection of optical emission from the supernova remnant G7.7-3.7

We present the first optical study of the supernova remnant (SNR) G7.7-3.7, with the aim of determining its evolutionary phase since it has been suggested to be the remnant of SN 386 AD. We obtained narrow-band images in the filters H$\alpha$ + [NII], H$\beta$, [OIII], [SII] that revealed faint optical emission in the southern region of the SNR consisting of two filaments elongated in the east-west direction aligned with the X-ray emitting region of the remnant. The filaments were seen in H$\alpha$ + [NII], [OIII] images and marginally in the [SII] images, with a non-detection in H$\beta$. Long-slit spectroscopy of three regions along one filament revealed large ratios of [SII] / H$\alpha$ = (1.6-2.5), consistent with that expected for a shock-heated SNR. The [SII] doublet ratio observed in two of the regions implies an upper limit for the electron density of the gas, with estimates falling below 400 cm$^{-3}$ and 600 cm$^{-3}$ in the respective areas. We discuss potential physical mechanisms that formed the observed optical filaments and we suggest that most likely they resulted by a collision of the SNR with a dense circumstellar shell lying at the southern region of the remnant.Comment: 10 pages, 5 figures, accepted in MNRA

Adenosine A2A Receptor Antagonists Affects NMDA Glutamate Receptor Function. Potential to Address Neurodegeneration in Alzheimer's Disease

Altres ajuts: This work was partially supported by the AARFD-17-503612 grant from the US Alzheimer's Association.(1) Background. N-methyl d-aspartate (NMDA) ionotropic glutamate receptor (NMDAR), which is one of the main targets to combat Alzheimer's disease (AD), is expressed in both neurons and glial cells. The aim of this paper was to assess whether the adenosine A2A receptor (A2AR), which is a target in neurodegeneration, may affect NMDAR functionality. (2) Methods. Immuno-histo/cytochemical, biophysical, biochemical and signaling assays were performed in a heterologous cell expression system and in primary cultures of neurons and microglia (resting and activated) from control and the APPSw,Ind transgenic mice. (3) Results. On the one hand, NMDA and A2A receptors were able to physically interact forming complexes, mainly in microglia. Furthermore, the amount of complexes was markedly enhanced in activated microglia. On the other hand, the interaction resulted in a novel functional entity that displayed a cross-antagonism, that could be useful to prevent the exacerbation of NMDAR function by using A2AR antagonists. Interestingly, the amount of complexes was markedly higher in the hippocampal cells from the APPSw,Ind than from the control mice. In neurons, the number of complexes was lesser, probably due to NMDAR not interacting with the A2AR. However, the activation of the A2AR receptors resulted in higher NMDAR functionality in neurons, probably by indirect mechanisms. (4) Conclusions. A2AR antagonists such as istradefylline, which is already approved for Parkinson's disease (Nouriast® in Japan and Nourianz® in the US), have potential to afford neuroprotection in AD in a synergistic-like fashion. i.e., via both neurons and microglia

Cannabidiol skews biased agonism at cannabinoid CB1 and CB2 receptors with smaller effect in CB1-CB2 heteroreceptor complexes

Currently, biased agonism is at the center stage of drug development approaches. We analyzed effects of a battery of cannabinoids plus/minus cannabidiol (CBD) in four functional parameters (cAMP levels, phosphorylation of extracellular signal–regulated kinases (ERK1/2), β-arrestin recruitment and label-free/DMR) in HEK-293T cells expressing cannabinoid receptors, CB or CB, or CB-CB heteroreceptor complexes. In all cases two natural agonists plus two selective synthetic agonists were used. Furthermore, the effect of cannabidiol, at a dose (100 nM) that does not allow significant binding to the orthosteric center of either receptor, was measured. From the huge amount of generated data, we would like to highlight that the two psychotropic molecules (Δ-tetrahydrocannabinol/THC and CP-55940) showed similar bias in CBR and that the bias of THC was particularly relevant toward MAPK pathway. Furthermore, THC did not activate the G protein coupled to CBR. Interestingly, the biased agonism was reduced when assays were performed in cells expressing the two receptors, thus suggesting that the heteromer allows less functional selectivity. In terms of cannabidiol action, the phytocannabinoid altered the functional responses, likely by allosteric means, and modified potency, agonist IC/EC values and biased agonism in qualitative and/or quantitative different ways depending on the agonist. The effect of cannabidiol on anandamide actions on both cannabinoid receptors was particularly noteworthy as was significantly different from that of other compounds. Results are a compendium of data on biased agonism on cannabinoid receptors in the absence and presence of cannabidiol. In addition, for the first time, GPCR biased agonism is characterized in an heteromeric context.This work was partially supported by grants from the Spanish Ministry of Economy and Competitiveness (Ref. no. BFU2015-64405-R and SAF2017-84117-R; they may include FEDER funds) and by grant 201413-30 from: Fundació la Marató de TV3Peer Reviewe