113 research outputs found
The radio to TeV orbital variability of the microquasar LSI+61303
Context: .The microquasar LS I +61 303 has recently been detected at TeV energies by the Cherenkov telescope MAGIC, presenting variability on timescales similar to its orbital period. This system has been intensively observed at different wavelengths during the last three decades, showing a very complex behavior along the orbit.Aims: .We aim to explain, using a leptonic model in the accretion scenario, the observed orbital variability and spectrum from radio to TeV energies of LS I +61 303.Methods: .We apply a leptonic model based on accretion of matter from the slow inhomogeneous equatorial wind of the primary star, assuming particle injection proportional to the accretion rate. The relativistic electron energy distribution within the binary system is computed taking into account convective/adiabatic and radiative losses. The spectral energy distribution (SED) has been calculated accounting for synchrotron and (Thomson/Klein Nishina -KN-) inverse Compton (IC) processes and the photon-photon absorption in the ambient photon fields. The angle dependence of the photon-photon and IC cross sections has been considered in the calculations.Results: .We reproduce the main features of the observed light curves from LS I +61 303 at radio, X-rays, high-energy (HE), and very high-energy (VHE) gamma-rays, and the whole spectral energy distribution.Conclusions: .Our model is able to explain the radio to TeV orbital variability taking into account that radiation along the orbit is strongly affected by the variable accretion rate, the magnetic field strength, and by the ambient photon field via dominant IC losses and photon-photon absorption at periastron.Fil: Bosch Ramon, Valentí. Universidad de Barcelona; EspañaFil: Paredes, Josep Maria. Universidad de Barcelona; EspañaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Ribó, Marc. Universidad de Barcelona; Españ
Projecte d'adequació d'edifici hoteler a petits apartaments turístics a la població de Canet de Mar
d’un edifici del S. XVIII, d’inici construït per a un ús residencial, i que en l’actualitat realitza
l’activitat d’hostal-residència.
La nova activitat que es proposa, be donada pel patrimoni familiar del propietari de l’edifici, ja
que la finca és el resultat d’una composició de diferents edificacions residencials unides entre
sí en la dècada dels seixanta, formant el que va ser un negoci familiar (actualment deshabitat,
excepte els mesos de juliol i agost). La proposta és realitzar un tipus de vivenda-apartament
per a lloguer, amb l’objectiu de reactivar el negoci anomenat i no recórrer a la venta del mateix.
En una primera instància, s’ha realitzat una diagnosi de l’edifici per tal de conèixer l’estat de
conservació, ja que cal anotar que és un edifici que té més de 100 anys. En el transcurs
d’aquesta diagnosi, concretament en la recerca d’informació per conèixer les adicions,
remuntes i tota mena de variacions que ha patit des de l’estat inicial, ens hem endinsat en la
tipologia de la casa tradicional dels pobles costaners, més en concret en la casa denominada
“casa de cos”. Per aquest motiu, s’ha cregut convenient realitzar un breu estudi d’aquesta
tipologia d’edificis i per l’altre banda, realitzar un estudi el més acurat possible de la història del
“nostre” habitacle per poder realitzar una diagnosi el més concreta possible, és a dir, conèixer
els processos constructius que es van emprar en la realització dels fonaments, l’estructura, es
tancaments, les cobertes, etc., ja que la presa de dades no era tot el correcte que es desitjava
per la impossibilitat de desmuntar fals sostres, realitzar cales, enretirar paviments i altres
tipologies de feines necessàries per realitzar la diagnosi.
Un cop finalitzada la recerca de la història del edifici en estudi, es passa a l’anàlisi concret
d’aquest, observant el tipus de lesions i/o patologies existents a causa de la unió d’edificacions
i modificacions de la seva volumetria sense estudis previs que indiquin que els canvis soferts
o, simplement, pel transcurs del temps, els quals, no hagin fet malbé la capacitat funcional de
l’edifici d’estudi.
Un cop finalitzada la diagnosi i realitzades les conclusions, s’ha passat a realitzar el projecte
d’adequació d’edifici hoteler a petits apartaments turístics. L’adequació de l’edifici s’ha realitzat
tal i com indiquen les normatives metropolitanes del municipi, aplicant els materials amb el
menor impacte possible intentant realitzar una rehabilitació el més sostenible possible i
realitzant el màxim nombre d’apartaments per un major rendibilitat. En el projecte d’adequació
s’ha inclòs un petit pla de manteniment per tal de prolongar la seva vida útil i per evitar
possibles lesions futures i una comparativa dels consum de CO2 en la rehabilitació projectada
envers a rehabilitacions comunes.
Per resumir breument l’edifici, es poden destacar les següents peculiaritats:
La primera peculiaritat és l’estructura. Es troba construïda en dos èpoques diferents, utilitzant
els medis característics, els materials i els sistemes constrictius de cadascuna d’elles. D’una
primera època, es poden apreciar volums executats amb forjats amb biguetes de fusta units
amb el pas del temps, amb edificacions construïdes en els anys 50-60, amb forjats biguetes de
formigó armat.
La segona peculiaritat la trobem en la seva façana principal, originaria del s.XVIII i actualment
catalogada com a d’interès pel departament arquitectònic de l’Ajuntament de Canet de Mar, i
que com especifiquem, gràcies a la informació recollida en la investigació de l’evolució de
l’edifici, no es la original ja que es va traslladar uns metres per una expropiació realitzada en
els anys 40. Aquest ha estat un tema a tindre en conte, ja que les distribucions han vingut
determinades per les obertures existents en façana
Brain germinoma presenting as a first psychotic episode in an adolescent male
International audienc
Simulations of an inhomogeneous stellar wind interacting with a pulsar wind in a binary system
Binary systems containing a massive star and a non-accreting pulsar present
strong interaction between the stellar and the pulsar winds. The properties of
this interaction, which largely determine the non-thermal radiation in these
systems, strongly depend on the structure of the stellar wind, which can be
clumpy or strongly anisotropic, as in Be stars. We study numerically the
influence of inhomogeneities in the stellar wind on the structure of the
two-wind interaction region. We carried out for the first time axisymmetric,
relativistic hydrodynamical simulations, with Lorentz factors of ~6 and
accounting for the impact of instabilities, to study the impact in the two-wind
interaction structure of an over-dense region of the stellar wind. We also
followed the evolution of this over-dense region or clump as it faces the
impact of the pulsar wind. For typical system parameters, and adopting a
stellar wind inhomogeneity with a density contrast >~10, clumps with radii of a
few percent of the binary size can significantly perturb the two-wind
interaction region, pushing the two-wind interface to <~40% of the initial
distance to the pulsar. After it is shocked, the inhomogeneity quickly expands
and is disrupted when it reaches the smallest distance to the pulsar. It
eventually fragments, being advected away from the binary system. The whole
interaction region is quite unstable, and the shocked pulsar wind can strongly
change under small perturbations. We confirm the sensitive nature of the
two-wind interaction structure to perturbations, in particular when the stellar
wind is inhomogeneous. For realistic over-dense regions of the stellar wind,
the interaction region may shrink by a factor of a few, with the shocked flow
presenting a complex spatial and temporal pattern. This can lead to strong
variations in the non-thermal radiation.Comment: This version matches the published version. The appendix at the end
of the article appears as on-line material in the journa
Chandra Observations of the Gamma-ray Binary LSI+61303: Extended X-ray Structure?
We present a 50 ks observation of the gamma-ray binary LSI+61303 carried out
with the ACIS-I array aboard the Chandra X-ray Observatory. This is the highest
resolution X-ray observation of the source conducted so far. Possible evidence
of an extended structure at a distance between 5 and 12 arcsec towards the
North of LSI+61303 have been found at a significance level of 3.2 sigma. The
asymmetry of the extended emission excludes an interpretation in the context of
a dust-scattered halo, suggesting an intrinsic nature. On the other hand, while
the obtained source flux, of F_{0.3-10 keV}=7.1^{+1.8}_{-1.4} x 10^{-12}
ergs/cm^2/s, and hydrogen column density, N_{H}=0.70+/-0.06 x 10^{22} cm^{-2},
are compatible with previous results, the photon index Gamma=1.25+/-0.09 is the
hardest ever found. In light of these new results, we briefly discuss the
physics behind the X-ray emission, the location of the emitter, and the
possible origin of the extended emission ~0.1 pc away from LSI+61303.Comment: 4 pages, 3 figures. Accepted for publication in ApJ Letter
Extreme precipitation events induce high fluxes of groundwater and associated nutrients to the coastal ocean
Current Submarine Groundwater Discharge (SGD) studies are commonly conducted under aquifer baseflow conditions, neglecting the influence of episodic events that can significantly increase the supply of nutrients and water. This limits our understanding of the social, biogeochemical, and ecological impacts of SGD. In this study, we evaluated the influence of an extreme precipitation event (EPE) on the magnitude of both the terrestrial and marine components of SGD. To do so, three seawater sampling campaigns were performed at a Mediterranean ephemeral stream-dominated basin after an extreme precipitation event (~90 mm in few hours) and in baseflow conditions. Results indicate that the groundwater flows of terrestrial and marine SGD after the extreme precipitation event were 1 order of magnitude higher than those in baseflow conditions. SGD induced by extreme precipitation events, which only take place a few days per year, represented up to one third of the annual discharge of groundwater and associated nutrients at the study site. This work accentuates the need to account for episodic increases in the supply of water and nutrients when aiming at providing reliable annual SGD estimates, particularly in the current context of climate change, since the occurrence of such events is expected to increase worldwide.This work was partly funded by the projects PID2019-110212RB- C22, CGL2016-77122-C2-1-R/2-R and PID2019-110311RB-C21 of the Spanish Government and the project TerraMar ACA210/18/00007 of the Catalan Water Agency. The authors want to express their thanks for the support of the Generalitat de Catalunya for MERS (2017 SGR-1588) and GHS (2017 SGR 1485) for additional funding. The authors would like to thank Maravillas Abad from ICM-CSIC for the analysis of nutrients. M. Diego-Feliu acknowledges the economic support from the FI-2017 fellowships of the Generalitat de Catalunya autonomous government (2017FI_B_00365). V. Rodellas acknowledges financial support from the Beatriu de Pinós postdoctoral program of the Generalitat de Catalunya autonomous government (2019-BP-00241). A. Alorda-Kleinglass acknowledges financial support from ICTA “Unit of Excellence” (MinECo, MDM2015‐440 0552‐17‐1) and PhD fellowship, BES‐2017‐080740. Albert Folch is a Serra Hunter Fellow. We would like to thank all colleagues from the Grup de Recerca en Radioactivitat Ambiental de Barcelona - GRAB (Universitat Autònoma de Barcelona). We would like to thank SIMMAR (Serveis Integrals de Manteniment del Maresme) and the Consell Comarcal del Maresme for the construction of the research site.Peer ReviewedPostprint (published version
Efficacy of modern antipsychotics in placebo-controlled trials in bipolar depression: a meta-analysis.
Randomized, controlled trials have demonstrated efficacy for second-generation antipsychotics in the treatment of acute mania in bipolar disorder. Despite depression being considered the hallmark of bipolar disorder, there are no published systematic reviews or meta-analyses to evaluate the efficacy of modern atypical antipsychotics in bipolar depression. We systematically reviewed published or registered randomized, double-blind, placebo-controlled trials (RCTs) of modern antipsychotics in adult bipolar I and/or II depressive patients (DSM-IV criteria). Efficacy outcomes were assessed based on changes in the Montgomery-Asberg Depression Rating Scale (MADRS) during an 8-wk period. Data were combined through meta-analysis using risk ratio as an effect size with a 95% confidence interval (95% CI) and with a level of statistical significance of 5% (p<0.05). We identified five RCTs; four involved antipsychotic monotherapy and one addressed both monotherapy and combination with an antidepressant. The two quetiapine trials analysed the safety and efficacy of two doses: 300 and 600 mg/d. The only olanzapine trial assessed olanzapine monotherapy within a range of 5-20 mg/d and olanzapine-fluoxetine combination within a range of 5-20 mg/d and 6-12 mg/d, respectively. The two aripiprazole placebo-controlled trials assessed doses of 5-30 mg/d. Quetiapine and olanzapine trials (3/5, 60%) demonstrated superiority over placebo (p<0.001). Only 2/5 (40%) (both aripiprazole trials) failed in the primary efficacy measure after the first 6 wk. Some modern antipsychotics (quetiapine and olanzapine) have demonstrated efficacy in bipolar depressive patients from week 1 onwards. Rapid onset of action seems to be a common feature of atypical antipsychotics in bipolar depression. Comment in The following popper user interface control may not be accessible. Tab to the next button to revert the control to an accessible version.Destroy user interface controlEfficacy of modern antipsychotics in placebo-controlled trials in bipolar depression: a meta-analysis--results to be interpreted with caution
Optical Photometric Monitoring of LS i +61 303
Three gamma-ray binaries, namely PSR B1259 63, HESS J0632+057 and LS I +61 303, contain compact objects orbiting around massive Be stars. Around periastron passage the compact objects should produce significant changes in the structure of the Be disks due to gravitational forces and eventually by ram pressure from the putative pulsar wind. Indeed, variability in the Hα emission line has been detected in all these systems, and optical periodic variability has been detected in one of them. However, there is lack of a systematic monitoring with accurate photometry, which could be used to constrain the shape of the disk during the periastron passage. This information is important to build accurate physical models to explain the broadband spectral energy distribution of these sources. Here we present an ongoing program to monitor the optical photometry of gamma-ray binaries and show preliminary results for the case of LS I +61 303
The social implications of Submarine Groundwater Discharge from an Ecosystem Services perspective: A systematic review
Altres ajuts: Acord transformatiu CRUE-CSICUnidad de excelencia María de Maeztu CEX2019-000940-MSubmarine Groundwater Discharge (SGD) is recognized as a fundamental hydrological process that supports many coastal biogeochemical cycles and social-ecological systems. However, very little has been investigated about how SGD affects society and, specifically, human well-being. This study systematically examines the published scientific literature on the social implications of SGD by using an Ecosystem Service (ES) perspective. Coastal services provided by ecosystems dependent on SGD are analyzed and clustered in the four main categories of Ecosystem Services (i.e., Provisioning, Supporting, Regulating and Cultural), which are in turn divided into subcategories defined as outcomes. This allows identifying and discussing both benefits and threats to coastal societies resulting from SGD outcomes. From the 1532 articles initially reviewed, the most frequently mentioned category was the supporting services (835) due to the mainstream trend in scientific literature to focus on the role of SGD as a process influencing coastal biogeochemical cycles. Conversely, cultural ES were mentioned in only 49 cases, which should not necessarily be interpreted as a lack of research or interest in this topic, but that this type of references are often not found in the scientific literature but in the grey literature. A detailed publication review was additionally conducted, identifying 114 case studies from 96 different locations worldwide that reported cases in which SGD had social implications on the well-being. Our review also shows how the different types of Ecosystem Services can have multiple synergies and trade-offs between them, resulting in unequal impacts among stakeholder groups. Overall, this study identifies research gaps related to Ecosystem Services provided by SGD as well as opportunities for further studies, while developing an analytical framework that relies on the Ecosystem Services approach to guide future research on the social implications of SGD
Evidence of coupling between the thermal and nonthermal emission in the gamma-ray binary LS I +61 303
The gamma-ray binary LS I +61 303 is composed of a Be star and a compact companion orbiting in an eccentric orbit. Variable flux modulated with the orbital period of ~26.5 d has been detected from radio to very high-energy gamma rays. In addition, the system presents a superorbital variability of the phase and amplitude of the radio outbursts with a period of ~4.6 yr. We present optical photometric observations of LS I +61 303 spanning ~1.5 yr and contemporaneous Hα equivalent width (EWHα) data. The optical photometry shows, for the first time, that the known orbital modulation suffers a positive orbital phase shift and an increase in flux for data obtained 1-yr apart. This behavior is similar to that already known at radio wavelengths, indicating that the optical flux follows the superorbital variability as well. The orbital modulation of the EWHα presents the already known superorbital flux variability but shows, also for the first time, a positive orbital phase shift. In addition, the optical photometry exhibits a lag of ~0.1-0.2 in orbital phase with respect to the EWHα measurements at similar superorbital phases, and presents a lag of ~0.1 and ~0.3 orbital phases with respect noncontemperaneous radio and X-ray outbursts, respectively. The phase shifts detected in the orbital modulation of thermal indicators, such as the optical flux and the EWHα, are in line with the observed behavior for nonthermal indicators, such as X-ray or radio emission. This shows that there is a strong coupling between the thermal and nonthermal emission processes in the gamma-ray binary LS I +61 303. The orbital phase lag between the optical flux and the EWHα is naturally explained considering different emitting regions in the circumstellar disk, whereas the secular evolution might be caused by the presence of a moving one-armed spiral density wave in the disk
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