247 research outputs found
On the kinematics of massive star forming regions: the case of IRAS 17233-3606
Direct observations of accretion disks around high-mass young stellar objects
would help to discriminate between different models of formation of massive
stars. However, given the complexity of massive star forming regions, such
studies are still limited in number. Additionally, there is still no general
consensus on the molecular tracers to be used for such investigations. Because
of its close distance and high luminosity, IRAS 17233-3606 is a potential good
laboratory to search for traces of rotation in the inner gas around the
protostar(s). Therefore, we selected the source for a detailed analysis of its
molecular emission at 230 GHz with the SMA. We systematically investigated the
velocity fields of transitions in the SMA spectra which are not affected by
overlap with other transitions, and searched for coherent velocity gradients to
compare them to the distribution of outflows in the region. Beside CO emission
we also used high-angular H2 images to trace the outflow motions driven by the
IRAS 17233-3606 cluster. We find linear velocity gradients in many transitions
of the same molecular species and in several molecules. We report the first
detection of HNCO in molecular outflows from massive YSOs. We discuss the CH3CN
velocity gradient taking into account various scenarios: rotation, presence of
multiple unresolved sources with different velocities, and outflow(s). Although
other interpretations cannot be ruled out, we propose that the CH3CN emission
might be affected by the outflows of the region. Higher angular observations
are needed to discriminate between the different scenarios. The present
observations, with the possible association of CH3CN with outflows in a few
thousands AU around the YSOs' cluster, (i) question the choice of the tracer to
probe rotating structures, and (ii) show the importance of the use of H2 images
for detailed studies of kinematics.Comment: accepted for publication in A&
Estimación de la velocidad de flujo del agua en cauces efímeros no aforados a partir de datos Lidar y GPS-RTK
The Manning formula is one of the most used to calculate the average velocity of water flow in ungauged channels. In order to be applied, it is necessary to measure in field the hydraulic radius (RH), the slope of the water surface (S), and to obtain the roughness coefficient (n), usually through tables created for this purpose. This involves a difficult, inefficient and subjective data collection in the field. This study evaluates the possibility to obtain these parameters in a more efficient manner, reducing the time of the process and allowing to work in larger areas. To achieve these objectives, the data used in this work were: 1) digital terrain models generated from airborne LiDAR data with a density of 2 points/ m2 , acquired when the channel was dry; 2) the height of the waterline and channel geometry measurements in the field using GPS; 3) Flow measurements. With this information, the velocity (Ve) was estimated and related to the average velocity of water flow (Vc) calculated from data measured in the field. The coefficient of determination between both velocity values was 73.52%, suggesting that the proposed methodology is useful to obtain the average velocity of flow, especially in remote areas or dry riverbeds
Transhumant Sheep grazing enhances ecosystem multifunctionality in productive mountain grasslands: a case study in the Cantabrian Mountains
.Understanding the effects of traditional livestock grazing abandonment on the
ability of mountain grasslands to sustain multiple ecosystem functions (ecosystem
multifunctionality; EMF) is crucial for implementing policies that promote grasslands
conservation and the delivery of multiple ecosystem services. In this study, we evaluated
the effect of short- and long-term transhumant sheep abandonment on EMF through a
grazing exclusion experiment in a grassland of the Cantabrian Mountains range (NW
Spain), where transhumant sheep flocks graze in summer. We considered four key
ecosystem functions, derived from vegetation and soil functional indicators measured
in the field: (A) biodiversity function, evaluated from total plant species evenness,
diversity and richness indicators; (B) forage production function, evaluated from cover
and richness of perennial and annual herbaceous species indicators; (C) carbon
sequestration function, evaluated from woody species cover and soil organic carbon
indicators; and (D) soil fertility function, evaluated from NH4C-N, NO3-N, P and K
content in the soil. The EMF index was calculated by integrating the four standardized
ecosystem functions through an averaging approach. Based on linear mixed modeling
we found that grazing exclusion induced significant shifts in the considered individual
ecosystem functions and also on EMF. Long-term livestock exclusion significantly
hindered biodiversity and forage production functions, but enhanced the carbon
sequestration function. Conversely, the soil fertility function was negatively affected by
both short- and long-term grazing exclusion. Altogether, grazing exclusion significantly
decreased overall EMF, especially in long-term livestock exclusion areas, while the
decline in EMF in short-term exclusions with respect to grazed areas was marginally
significant. The results of this study support the sustainability of traditional transhumance
livestock grazing for promoting the conservation of grasslands and their ecosystem
function in mountain regions.S
Site-selective symmetries of Eu3+-doped BaTiO3 ceramics: a structural elucidation by optical spectroscopy
Eu3+-Doped BaTiO3 ceramics with dopant contents between 0 and 10 mol% were prepared by sol–gel synthesis based on the nominal compositions (Ba1−3xEu2x)TiO3 and Ba(Ti1−xEux)O3−x/2, where two possible substitution mechanisms are addressed. By means of optical spectroscopy, our study gives a plausible elucidation of Eu3+ site occupation in micron-sized BaTiO3 particles. Time-resolved fluorescence line narrowing (TRFLN) shows the presence of five different crystal field sites for europium ions and possible symmetries are inferred for each one. The solubility limit of the lanthanide ion was found to be about 3 mol%. The experimental results are consistent with the preference of Eu3+ to occupy Ba2+ sites regardless of the nominal compositions and target substitution mechanism. However, TRFLN results showed that the dopant could also occupy Ti4+ sites, highlighting the amphoteric character of Eu3+. The existence of anti-Stokes and Stokes vibronic sidebands in the 5D0 → 7F0,1 transitions of Eu3+ ions is confirmed. This can explain the lack of resolution found in room temperature spectra of these transitions due to vibronic mixing of the excited levels. The existence of non-equivalent europium sites with different spectroscopic properties could have an impact on the optical properties of doped-BaTiO3 ceramics and associated applications
Iron–Gold Nanoflowers: A Promising Tool for Multimodal Imaging and Hyperthermia Therapy
The development of nanoplatforms prepared to perform both multimodal imaging and combined therapies in a single entity is a fast-growing field. These systems are able to improve diagnostic accuracy and therapy success. Multicomponent Nanoparticles (MCNPs), composed of iron oxide and gold, offer new opportunities for Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) diagnosis, as well as combined therapies based on Magnetic Hyperthermia (MH) and Photothermal Therapy (PT). In this work, we describe a new seed-assisted method for the synthesis of Au@Fe Nanoparticles (NPs) with a flower-like structure. For biomedical purposes, Au@Fe NPs were functionalized with a PEGylated ligand, leading to high colloidal stability. Moreover, the as-obtained Au@Fe-PEG NPs exhibited excellent features as both MRI and CT Contrast Agents (CAs), with high r2 relaxivity (60.5 mM−1⋅s−1) and X-ray attenuation properties (8.8 HU mM−1⋅HU). In addition, these nanoflowers presented considerable energy-to-heat conversion under both Alternating Magnetic Fields (AMFs) (∆T ≈ 2.5 °C) and Near-Infrared (NIR) light (∆T ≈ 17 °C). Finally, Au@Fe-PEG NPs exhibited very low cytotoxicity, confirming their potential for theranostics applications.Spanish Ministry of Economy, Industry and Competitiveness CTQ2017-86655-RSpanish Ministry of Science and Innovation PID2020-118448RB-C21Spanish Ministry of Science and Innovation PID2020-113108RB-I00MCIN/AEI/10.13039/501100011033Fondo Social de la DGA (grupos DGA) PGC2018-096016-B-I00Regional Ministry of Health of Andalusia OH-0026-2018Regional Ministry of Health of Andalusia PAIDI 2020. P20_0072
Iron–Gold Nanoflowers: A Promising Tool for Multimodal Imaging and Hyperthermia Therapy
The development of nanoplatforms prepared to perform both multimodal imaging and combined therapies in a single entity is a fast-growing field. These systems are able to improve diagnostic accuracy and therapy success. Multicomponent Nanoparticles (MCNPs), composed of iron oxide and gold, offer new opportunities for Magnetic Resonance Imaging (MRI) and Computed To-mography (CT) diagnosis, as well as combined therapies based on Magnetic Hyperthermia (MH) and Photothermal Therapy (PT). In this work, we describe a new seed-assisted method for the synthesis of Au@Fe Nanoparticles (NPs) with a flower-like structure. For biomedical purposes, Au@Fe NPs were functionalized with a PEGylated ligand, leading to high colloidal stability. Moreover, the as-obtained Au@Fe-PEG NPs exhibited excellent features as both MRI and CT Contrast Agents (CAs), with high r2 relaxivity (60.5 mM-1·s-1 ) and X-ray attenuation properties (8.8 HU mM-1·HU). In addition, these nanoflowers presented considerable energy-to-heat conversion under both Alternating Magnetic Fields (AMFs) (¿T ˜ 2.5¿C) and Near-Infrared (NIR) light (¿T ˜ 17¿C). Finally, Au@Fe-PEG NPs exhibited very low cytotoxicity, confirming their potential for theranostics applications. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Classical operators on the Hörmander algebras
We study the integration operator, the differentiation operator
and more general differential operators on radial Fr´echet or (LB) H¨ormander
algebras of entire functions. We analyze when these operators are power
bounded, hypercyclic and (uniformly) mean ergodic.This research was partially supported by MEC and FEDER Project MTM2010-15200. The research of M. J. Beltran was also supported by grant F.P.U. AP2008-00604 and Programa de Apoyo a la Investigacion y Desarrollo de la UPV PAID-06-12, and the research of J. Bonet and C. Fernandez, by GVA under Project PROMETEOII/2013/013.Beltrán Meneu, MJ.; Bonet Solves, JA.; Fernández, C. (2015). Classical operators on the Hörmander algebras. Discrete and Continuous Dynamical Systems - Series A. 35(2):637-652. https://doi.org/10.3934/dcds.2015.35.637S63765235
Reciclado de escorias de fondo de central térmica para su uso como áridos en la elaboración de componentes prefabricados de hormigón
The need to eliminate waste generates costs. When considering the preservation of the environment, the minimization of the consumption of natural resources and energy savings criteria, the need and advisability of studying the feasibility of waste re-use seems clear. However, waste re-use depends on whether they are economically competitive. Therefore, the aim of this study is to evaluate the possible use of slag from a steam power station as aggregate in the manufacture of concrete.
This study included the determination of the physical, chemical and thermal properties of the material, comparing the results to those required by the Spanish structural concrete code (EHE) in determining their acceptance or rejection as a concrete component. The ultimate aim of the research was to determine the highest slag content that could be added to concrete without modifying its strength or durability, with a view to obtaining savings in the manufacture of precast structures.La necesidad de eliminar residuos genera gastos. Considerando criterios de conservación ambiental, minimización del consumo de recursos naturales y ahorro de energía parece claro la necesidad y conveniencia de estudiar la viabilidad del uso de residuos. Sin embargo la utilización de residuos depende de que sean competitivos económicamente. Por tanto el propósito de esta investigación es evaluar el posible uso de las escorias de fondo de una central térmica como áridos para la fabricación de hormigón. En este estudio se incluye la determinación de características físicas, químicas y térmicas y se han comparado los resultados a los requeridos por la EHE para determinar su aceptación o rechazo como componente de un hormigón. El objetivo final de la investigación responde a la utilización de hormigón con el máximo contenido en escorias sin modificar las condiciones de resistencia y durabilidad, consiguiendo un ahorro económico en la fabricación de estructuras prefabricadas
In1-ghrelin splicing variant is overexpressed in pituitary adenomas and increases their aggressive features
Pituitary adenomas comprise a heterogeneous subset of pathologies causing serious comorbidities, which
would benefit from identification of novel, common molecular/cellular biomarkers and therapeutic targets.
The ghrelin system has been linked to development of certain endocrine-related cancers. Systematic analysis
of the presence and functional implications of some components of the ghrelin system, including native
ghrelin, receptors and the recently discovered splicing variant In1-ghrelin, in human normal pituitaries (n
5 11) and pituitary adenomas (n 5 169) revealed that expression pattern of ghrelin system suffers a clear
alteration in pituitary adenomasas comparedwith normal pituitary, where In1-ghrelin is markedly
overexpressed. Interestingly, in cultured pituitary adenoma cells In1-ghrelin treatment (acylated peptides at
100 nM; 24–72 h) increasedGHandACTHsecretion, Ca21 and ERK1/2 signaling and cell viability, whereas
In1-ghrelin silencing (using a specific siRNA; 100 nM) reduced cell viability. These results indicate that an
alteration of the ghrelin system, specially its In1-ghrelin variant, could contribute to pathogenesis of
different pituitary adenomas types, and suggest that this variant and its related ghrelin system could provide
new tools to identify novel, more general diagnostic, prognostic and potential therapeutic targets in
pituitary tumors
A High Dynamic Range ASIC for Time of Flight PET with monolithic crystals
The HRFlexToT is a 16-channel ASIC for SiPM anode readout designed for Positron Emission Tomography (PET) applications that features high dynamic range (>8 bits), low input impedance, common cathode connection, high speed and low power (~3.5 mW/ch). The ASIC has been manufactured using XFAB 0.18 mm CMOS technology. The main characteristics of the HRFlexToT, compared to its predecessor, are a new energy measurement readout providing a linear Time Over Threshold (ToT) with an extended dynamic range, lower power consumption and better timing response. Initial measurements show a linearity error below 3%. Single Photon Time Resolution (SPTR) measurements performed using a Hamamatsu MPPC S13360-3050CS (3x3 mm2 pixel, 50 umm cell) shows 30% improvement with respect to the previous version of the ASIC, setting this specification in the order of 141 ps FWHM and reducing 3 times power consumption. It is important to highlight that an SPTR of 141 ps FWHM is, according to the best of our knowledge, the best resolution achieved so far for this sensor. Coincidence Time Resolution (CTR) measurements are expected to be performed during 2018
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