Interacciones en monocapas de colesterol con ácidos grasos saturados e insaturados (omega-3, omega-6 y omega-9)

El tipo de monocapa generada por los ácidos grasos estudiados depende de sus características estructurales de tal forma que la saturación de las cadenas hidrocarbonadas de las moléculas de ácido esteárico (18:0) facilita la constitución de una monocapa muy condensada y un valor del área límite muy pequeño. La presencia de insaturaciones en las cadenas hidrocarbonadas de las moléculas reduce drásticamente su grado de empaquetamiento, lográndose la formación de monocapas en estado superficial líquido expandido. Al aumentar el número de dobles enlaces, los valores de las áreas límites aumentan y los de los módulos de compresibilidad decrecen. El aumento del número de átomos de carbono en la cadena hidrocarbonada incrementa ligeramente el área límite de la monocapa, sin apenas afectar al módulo de compresibilidad de la misma. Mediante el uso de modelos moleculares se interpretaron, a partir del registro de espesores relativos, las diferentes conformaciones experimentadas por las moléculas de las sustancias estudiadas para cada uno de los estados físicos por los que atraviesan las monocapas. Las monocapas de tipo condensado (colesterol y ácido esteárico) presentan sus moléculas en una posición perpendicular respecto a la superficie del sustrato acuoso en el momento previo al colapso; durante la fase gas se hallan en una posición casi horizontal, con un grado de inclinación de 13°. Las monocapas expandidas (ácidos grasos insaturados) están posicionadas prácticamente de forma perpendicular a la horizontal instantes antes del colapso, mientras que, en la fase gas, presentan una inclinación de entre 36 y 42° respecto de la superficie del agua. El estudio de las características de las monocapas mixtas formadas por colesterol y ácidos grasos evidencia la existencia de interacciones de tipo atractivo entre los componentes en el caso de ácidos grasos insaturados. En el sistema colesterol-ácido esteárico (saturado) ambos componentes son inmiscibles en la interfaz aire/agua. Las evidencias de este diferente comportamiento fueron las siguientes: Las interacciones entre el colesterol y los ácidos grasos insaturados aumentan con el grado de insaturación de las cadenas hidrocarbonadas de los ácidos hasta alcanzar su máxima expresión cuando el número de dobles enlaces es 3. Por otra parte, la interacción es mayor cuando el sistema mixto está formado por ácidos grasos de la serie omega-3 que cuando se trata de ácidos omega-6. Además, la composición de las mezclas es importante, observándose la máxima interacción en las de fracción molar Xácido graso = 0,5. Los resultados obtenidos permiten formular una hipótesis según la cual los ácidos grasos insaturados que llegan al intestino tras la digestión de las grasas en el estómago interaccionan con el colesterol libre que se libera en el intestino tras el proceso de hidrólisis de los ésteres de colesterol de la dieta. De este modo, la formación de un complejo colesterol-ácido graso de estequiometria 1:1 (fracción molar 0,5), consecuencia de la interacción, retira del intestino hacia las heces parte del colesterol libre existente. El resto de colesterol que no forma parte del complejo se re-esterifica de nuevo y es enviado al hígado a través de los quilomicrones para que este órgano haga uso de él según sus requerimientos. Esta sería una forma de disminuir el contenido de colesterol en el cuerpo humano

MLS-SPH-ALE: A Review of Meshless-FV Methods and a Unifying Formulation for Particle Discretizations

Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.[Abstract:] Mesh-based and particle methods were conceived as two different discretization strategies to solve partial differential equations. In the last two decades computational methods have diversified and a myriad of hybrid formulations that combine elements of these two approaches have been developed to solve Computational fluid dynamics problems. In this work we present a review about the meshless-FV family of methods, an analysis is carried out showing that the MLS-SPH-ALE method can be considered as a general formulation from which a set of particle-based methods can be recovered. Moreover, we show the relations between the MLS-SPH-ALE method and the finite volume method. The MLS-SPH-ALE method is a versatile particle-based method that was developed to circumvent the consistency issues of particle methods caused by the use of the kernel approximation. The MLS-SPH-ALE method is developed from the differential equation in ALE form using the partition unity property which is automatically fulfilled by the Moving Least Squares approximation.The authors gratefully acknowledge the support provided by the [Grant PID2021-125447OB-I00] funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”, and the funds by [Grant TED2021–129805B-I00] funded by MCIN/AEI/ 10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”. They also acknowledge the funding provided by the Xunta de Galicia (Grant #ED431C 2022/06). J. Fernández-Fidalgo acknowledges the support provided by “Ayudas para la recualificación del sistema universitario español para 2021–2023. Modalidad Margarita Salas RSU.UDC.MS20" by the Ministerio de Universidades of the Spanish Government and European Union through the NextGenerationEU funds.Xunta de Galicia; ED431C 2022/0

Greenhouse Gas Emissions and Energy Consumption of Coastal Ecosystem Enhancement Programme through Sustainable Artificial Reefs in Galicia

[Abstract] The principle of sustainability should condition a project in which artificial reefs are being installed to protect biodiversity as well as enhance costal ecosystems. In particular, this principle should be taken into account in the logistical processes related to manufacture and transport. This study assesses the global warming potential (GWP) and cumulative energy demand (CED) of developing a coastal ecosystem enhancement programme in the estuary region of Galicia, north-western Spain. The focus is on the processes involved in creating green artificial reefs (GARs): manufacture, transport and installation. The starting point is the supply chain for the green artificial reef (GAR) units; greenhouse gas emissions (GHG) and energy needs for each phase are analysed. Various scenarios are considered to determine which options are indeed available when it comes to establishing the supply chain. Different types of energy supplies, different options for the location of production centres, as well as different means of transport were studied. Results reveal the critical phases for selecting how the GAR units must be produced, transported by road and sea and then installed in their permanent location.Xunta de Galicia; CN-10MMA003C

A novel pathogenic mechanism for cerebellar lesions produced by Solanum bonariense in cattle

Intoxication with Solanum bonariense in cattle causes cerebellar cortical degeneration with perikaryal vacuolation, axonal swelling, and death primarily of Purkinje cells, with accumulation of electron-dense residual storage bodies in membrane-bound vesicles. The pathogenesis of this disease is not fully understood. Previously, we proposed that inhibition of protein synthesis in Purkinje cells among other altered metabolic pathways could lead to cytoskeletal alterations, subsequently altering cell-specific axonal transport. In the present study, immunohistochemical and histochemical methods were used to identify neuronal cytoskeletal alterations and axonal loss, demyelination, and astrogliosis in the cerebellum of intoxicated bovines. Samples of cerebellum from 3 natural and 4 experimental cases and 2 control bovines were studied. Immunoreactivity against neurofilament (NF)-200KDa confirmed marked loss of Purkinje neurons, and phospho-NF protein, β-tubulin, and affinity reaction against phalloidin revealed an altered perikaryal distribution of neuronal cytoskeletal proteins in the remaining Purkinje cells in intoxicated cattle. Reactive astrogliosis in every layer of the cerebellar cortex was also observed with anti–glial fibrillary acidic protein immunohistochemistry. In affected cattle, demyelination and axonal loss in the cerebellar white matter, as well as basket cell loss were demonstrated with Klüver–Barrera and Bielschowsky stains, respectively. Based on these results, we propose that neuronal cytoskeletal alterations with subsequent interference of the axonal transport in Purkinje cells may play a relevant role in the pathogenesis of this neurodegenerative disorder, and also that demyelination and axonal loss in the cerebellar white matter, as well as astrogliosis in the gray matter, likely occur secondarily to Purkinje cell degeneration and death.Facultad de Ciencias Veterinaria

A novel pathogenic mechanism for cerebellar lesions produced by Solanum bonariense in cattle

Intoxication with Solanum bonariense in cattle causes cerebellar cortical degeneration with perikaryal vacuolation, axonal swelling, and death primarily of Purkinje cells, with accumulation of electron-dense residual storage bodies in membrane-bound vesicles. The pathogenesis of this disease is not fully understood. Previously, we proposed that inhibition of protein synthesis in Purkinje cells among other altered metabolic pathways could lead to cytoskeletal alterations, subsequently altering cell-specific axonal transport. In the present study, immunohistochemical and histochemical methods were used to identify neuronal cytoskeletal alterations and axonal loss, demyelination, and astrogliosis in the cerebellum of intoxicated bovines. Samples of cerebellum from 3 natural and 4 experimental cases and 2 control bovines were studied. Immunoreactivity against neurofilament (NF)-200KDa confirmed marked loss of Purkinje neurons, and phospho-NF protein, β-tubulin, and affinity reaction against phalloidin revealed an altered perikaryal distribution of neuronal cytoskeletal proteins in the remaining Purkinje cells in intoxicated cattle. Reactive astrogliosis in every layer of the cerebellar cortex was also observed with anti–glial fibrillary acidic protein immunohistochemistry. In affected cattle, demyelination and axonal loss in the cerebellar white matter, as well as basket cell loss were demonstrated with Klüver–Barrera and Bielschowsky stains, respectively. Based on these results, we propose that neuronal cytoskeletal alterations with subsequent interference of the axonal transport in Purkinje cells may play a relevant role in the pathogenesis of this neurodegenerative disorder, and also that demyelination and axonal loss in the cerebellar white matter, as well as astrogliosis in the gray matter, likely occur secondarily to Purkinje cell degeneration and death.Facultad de Ciencias Veterinaria

El clima de las ciudades: isla de calor de Salamanca

We have determined the existence of the urban heat island (UHI) in a medium-sized city, with an extreme climate and few important foci of industrial pollution. It was seen that urban warming can arise in cities of these characteristics, being able to influence in the alive beings of the zone. By comparing the temperature series in an urban area and those from a nearby rural area, we studied the temporal evolution of the intensity of the UHI for the three-year period between 1996 and 1998. We detected two phenomenons: nocturnal heat island, when the difference of temperature between city and rural zone is positive, and diurnal heat island, when is negative. The most intense nocturnal heat island was seen in autumn, and the most intense diurnal heat island was seen in spring. Statistical study of the annual series corresponding to the night-time heat island permits a definition for Salamanca: a weak island, such as the one showing an intensity lower than 2.0 oC, a moderate island, if the intensity lies between 2.0 oC and 4.0 oC, and an intense island when a values greater than 4.0 oC is passed.En este trabajo se ha determinado la existencia de la isla de calor urbana (ICU), en una ciudad de tamaño medio, con un clima extremado y focos industriales de poca actividad. Con lo que se puede comprobar cómo afecta el calentamiento urbano a ciudades de estas características, pudiendo influir en los seres vivos de la zona. La existencia del fenómeno isla de calor, y su evolución en el tiempo, se han observado comparando los datos de temperatura registrados en una estación meteorológica situada en la ciudad, con los de otra estación fuera del radio de acción de la urbe, durante el período 1996-1998. Se han detectado dos fenómenos: la isla de calor nocturna, cuando la diferencia térmica entre la ciudad y la zona rural es positiva, que presenta sus valores más altos en otoño, y la isla de calor diurna, cuando la diferencia es negativa, que presenta sus valores más altos en primavera. Realizando un estudio estadístico de la evolución anual de la isla de calor nocturna en Salamanca, podemos definir isla de calor débil si su intensidad es inferior a 2 oC, moderada si se encuentra entre 2 oC y 4 oC e intensa si supera los 4 oC

Statistics of VHE γ-rays in temporal association with radio giant pulses from the Crab pulsar

Aims. The aim of this study is to search for evidence of a common emission engine between radio giant pulses (GPs) and very-high-energy (VHE, E& x2004;> & x2004;100 GeV) gamma-rays from the Crab pulsar. Methods. We performed 16 h of simultaneous observations of the Crab pulsar at 1.4 GHz with the Effelsberg radio telescope and the Westerbork Synthesis Radio Telescope (WSRT), and at energies above 60 GeV we used the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes. We searched for a statistical correlation between the radio and VHE gamma-ray emission with search windows of different lengths and different time lags to the arrival times of a radio GP. A dedicated search for an enhancement in the number of VHE gamma-rays correlated with the occurrence of radio GPs was carried out separately for the P1 and P2 phase ranges, respectively. Results. In the radio data sample, 99444 radio GPs were detected. We find no significant correlation between the GPs and VHE photons in any of the search windows. Depending on phase cuts and the chosen search windows, we find upper limits at a 95% confidence level on an increase in VHE gamma-ray events correlated with radio GPs between 7% and 61% of the average Crab pulsar VHE flux for the P1 and P2 phase ranges, respectively. This puts upper limits on the flux increase during a radio GP between 12% and 2900% of the pulsed VHE flux, depending on the search window duration and phase cuts. This is the most stringent upper limit on a correlation between gamma-ray emission and radio GPs reported so far

MAGIC detection of very high energy gamma-ray emission from the low-luminosity blazar 1ES 1741+196

We present the first detection of the nearby (z=0.084) low-luminosity BL Lac object 1ES 1741+196 in the very high energy (VHE: E>100 GeV) band. This object lies in a triplet of interacting galaxies. Early predictions had suggested 1ES 1741+196 to be, along with several other high-frequency BL Lac sources, within the reach of MAGIC detectability. Its detection by MAGIC, later confirmed by VERITAS, helps to expand the small population of known TeV BL Lacs. The source was observed with the MAGIC telescopes between 2010 April and 2011 May, collecting 46 h of good quality data. These observations led to the detection of the source at 6.0 σ confidence level, with a steady flux F(> 100 GeV) = (6.4 ± 1.7_(stat) ± 2.6_(syst)) • 10^(−12) ph cm^(−2) s^( −1) and a differential spectral photon index Γ = 2.4 ± 0.2_(stat) ± 0.2_(syst) in the range of ∼80 GeV - 3 TeV. To study the broad-band spectral energy distribution (SED) simultaneous with MAGIC observations, we use KVA, Swift/UVOT and XRT, and Fermi/LAT data. One-zone synchrotron-self-Compton (SSC) modeling of the SED of 1ES 1741+196 suggests values for the SSC parameters that are quite common among known TeV BL Lacs except for a relatively low Doppler factor and slope of electron energy distribution. A thermal feature seen in the SED is well matched by a giant elliptical’s template. This appears to be the signature of thermal emission from the host galaxy, which is clearly resolved in optical observations

Very high-energy gamma-ray follow-up program using neutrino triggers from IceCube

We describe and report the status of a neutrino-triggered program in IceCube that generates real-time alerts for gamma-ray follow-up observations by atmospheric-Cherenkov telescopes (MAGIC and VERITAS). While IceCube is capable of monitoring the whole sky continuously, high-energy gamma-ray telescopes have restricted fields of view and in general are unlikely to be observing a potential neutrino-flaring source at the time such neutrinos are recorded. The use of neutrino-triggered alerts thus aims at increasing the availability of simultaneous multi-messenger data during potential neutrino flaring activity, which can increase the discovery potential and constrain the phenomenological interpretation of the high-energy emission of selected source classes (e. g. blazars). The requirements of a fast and stable online analysis of potential neutrino signals and its operation are presented, along with first results of the program operating between 14 March 2012 and 31 December 2015

A search for spectral hysteresis and energy-dependent time lags from x-ray and TeV gamma-ray observations of Mrk 421

Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three " target-of-opportunity" observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observations from other gamma-ray facilities (MAGIC and Fermi-Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e. g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at greater than or similar to 4 x 10(-4) Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies