415 research outputs found
First Triassic tetrapod (Sauropterygia, Nothosauridae) from Castilla y León: evidence of an unknown taxon for the Spanish record
Several vertebrae of a sauropterygian specimen have been recovered in Fuencaliente de Medinaceli (Soria Province, Castilla y León, Spain). The remains come from Middle–Upper Triassic Muschelkalk Facies. This finding represents the first documented evidence of a Triassic tetrapod in Castilla y León. The vertebrae belong to Nothosaurus, a sauropterygian genus found in Europe, Middle East, North of Africa and China. This genus is poorly-known in the Iberian record. The new remains constitute the first evidence of the species Nothosaurus giganteus, or a related taxon, in the Iberian Peninsula. This study reveals the occurrence of at least two species of the sauropterygian Nothosaurus in the Spanish record.Varias vértebras de un ejemplar de sauropterigio han sido encontradas en Fuencaliente de Medinaceli (Provincia de Soria, Castilla y León, España). Los restos provienen de niveles del Triásico Medio tardío (Ladiniense superior) de la parte superior de las Facies Muschelkalk. Estos elementos representan la primera evidencia documentada de un tetrápodo triásico en Castila y León. Las vértebras pertenecen a Nothosaurus, un género de sauropterigio encontrado en Europa, Oriente Próximo, el norte de África y China. Este género es mal conocido en el registro ibérico. Los nuevos restos constituyen la primera evidencia de la especie Nothosaurus giganteus, o de un taxón emparentado, en la Península Ibérica, siendo atribuidos a Nothosaurus cf. giganteus. Este estudio revela la presencia de, al menos, dos especies diferentes de Nothosaurus en el registro ibérico
Accurate and Wide-Field-of-View MEMS-Based Sun Sensor for Industrial Applications
This paper describes the design, fabrication, sim-
ulation, and experimental results of an improved miniaturized
two-axis sun sensor for industrial applications, created by adapt-
ing a technology used previously in satellite applications. The
sensor for each axis is composed of six photodiodes integrated in
a crystalline-silicon substrate and a layer of cover glass, which
is used to protect the silicon and to hold the windows. The high
precision is obtained by the subdivision of the field of view, which is ± 60
◦
, with a resolution of 0.1
◦
. Each region is controlled by an
independent high-precision solar sensor. The sensor can be used
for sun-tracking applications in a photovoltaic system, heliostat
concentration plants, and lighting applications.Gobierno de España. AYA2009- 07188-E, ACI2010-1094, AIC-B-2011-0702 (Sensosol project)Junta de Andalucía (España) P08-TIC-03590 (Satsol project
Lethality caused by ADP-glucose accumulation is suppressed by salt-induced carbon flux redirection in cyanobacteria
Cyanobacteria are widely distributed photosynthetic organisms. During the day they store carbon, mainly as glycogen,
to provide the energy and carbon source they require for maintenance during the night. Here, we generate a mutant
strain of the freshwater cyanobacterium Synechocystis sp. PCC 6803 lacking both glycogen synthases. This mutant
has a lethal phenotype due to massive accumulation of ADP-glucose, the substrate of glycogen synthases. This accumulation leads to alterations in its photosynthetic capacity and a dramatic decrease in the adenylate energy charge
of the cell to values as low as 0.1. Lack of ADP-glucose pyrophosphorylase, the enzyme responsible for ADP-glucose
synthesis, or reintroduction of any of the glycogen synthases abolishes the lethal phenotype. Viability of the glycogen
synthase mutant is also fully recovered in NaCl-supplemented medium, which redirects the surplus of ADP-glucose
to synthesize the osmolite glucosylglycerol. This alternative metabolic sink also suppresses phenotypes associated
with the defective response to nitrogen deprivation characteristic of glycogen-less mutants, restoring the capacity to
degrade phycobiliproteins. Thus, our system is an excellent example of how inadequate management of the adenine
nucleotide pools results in a lethal phenotype, and the influence of metabolic carbon flux in cell viability and fitness.España, Ministerio de Economía y Competitividad (MINECO) (grant BFU2013-41712-P and BIO2016-75634-P)España, Junta de Andalucía (P12-BIO-1119
Validation of virtual water phantom software for pre-treatment verification of single-isocenter multiple-target stereotactic radiosurgery
Objectiu múltiple; SRS; Fantasma virtualObjetivo múltiple; SRS; Fantasma virtualMultiple‐target; SRS; Virtual phantomThe aim of this study was to benchmark the accuracy of the VIrtual Phantom Epid dose Reconstruction (VIPER) software for pre-treatment dosimetric verification of multiple-target stereotactic radiosurgery (SRS). VIPER is an EPID-based method to reconstruct a 3D dose distribution in a virtual phantom from in-air portal images. Validation of the VIPER dose calculation was assessed using several MLC-defined fields for a 6 MV photon beam. Central axis percent depth doses (PDDs) and output factors were measured with an ionization chamber in a water tank, while dose planes at a depth of 10 cm in a solid flat phantom were acquired with radiochromic films. The accuracy of VIPER for multiple-target SRS plan verification was benchmarked against Monte Carlo simulations. Eighteen multiple-target SRS plans designed with the Eclipse treatment planning system were mapped to a cylindrical water phantom. For each plan, the 3D dose distribution reconstructed by VIPER within the phantom was compared with the Monte Carlo simulation, using a 3D gamma analysis. Dose differences (VIPER vs. measurements) generally within 2% were found for the MLC-defined fields, while film dosimetry revealed gamma passing rates (GPRs) ≥95% for a 3%/1 mm criteria. For the 18 multiple-target SRS plans, average 3D GPRs greater than 93% and 98% for the 3%/2 mm and 5%/2 mm criteria, respectively. Our results validate the use of VIPER as a dosimetric verification tool for pre-treatment QA of single-isocenter multiple-target SRS plans. The method requires no setup time on the linac and results in an accurate 3D characterization of the delivered dose
Carbosilane dendritic nanostructures, highly versatile platforms for pharmaceutical applications
Dendrimers are multifunctional molecules with well-defined size and structure due to the step-by-step synthetic procedures required in their preparation. Dendritic constructs based on carbosilane scaffolds present carbon-carbon and carbon-silicon bonds, which results in stable, lipophilic, inert, and flexible structures. These properties are highly appreciated in different areas, including the pharmaceutical field, as they can increase the interaction with cell membranes and improve the therapeutic action. This article summarizes the most recent advances in the pharmaceutical applications of carbosilane dendritic molecules, from therapeutics to diagnostics and prevention tools. Dendrimers decorated with cationic, anionic, or other moieties, including metallodendrimers; supramolecular assemblies; dendronized nanoparticles and surfaces; as well as dendritic networks like hydrogels are described. The collected examples confirm the potential of carbosilane dendrimers and dendritic materials as antiviral or antibacterial agents; in therapy against cancer, neurodegenerative disease, or oxidative stress; or many other biomedical applications.This article is categorized under:Nanotechnology Approaches to Biology > Nanoscale Systems in BiologyTherapeutic Approaches and Drug Discovery > Nanomedicine for Infectious DiseaseTherapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic DiseaseMinisterio de Economía y CompetitividadComunidad de MadridJunta de Comunidades de Castilla-La ManchaUniversidad de Alcal
Argumentación y modelos explicativos de los estudiantes de séptimo grado en torno al concepto tejido muscular
La argumentación es una competencia indispensable en los procesos de enseñanza y aprendizaje de los conceptos científicos en el aula de ciencias. En el presente trabajo se establecieron relaciones entre el desarrollo de la argumentación y los modelos explicativos del concepto tejido muscular. Para esto, se desarrollaron tres momentos de investigación: a) diagnóstico de los niveles argumentativos y de los modelos explicativos sobre el concepto mediante la aplicación de un cuestionario de pregunta abierta; b) intervención, etapa en la cual desde los datos obtenidos en el momento de diagnóstico, se diseñó y aplicó una secuencia didáctica con la que se intervinieron los modelos identificados y se promovieron procesos argumentativos; c) cierre, en donde se aplicó el cuestionario por segunda vez para identificar cambios en los modelos explicativos de los estudiantes sobre el concepto y en los niveles de argumentación que mostraron sus respuestas. Los resultados muestran cambios significativos tanto en los modelos como en los niveles explicativos lo que permite afirmar que un cambio en el nivel conceptual de los estudiantes permite realizar mejores argumentos sobre los temas discutidos
La percepción en Tepic, sobre la producción audiovisual
The perception people have of audiovisual production in Tepic, Nayarit, is based on the different types of production that is performed and the relationship between the cost - benefit these entail. In the present study the social context in which the audiovisual production in the State of Nayarit, the perception of audiovisual producers and socio - political - economic conditions of this industry develops addressed.La percepción que se tiene de la producción audiovisual en Tepic, Nayarit, se basa en los diferentes tipos de producción que se realiza y la relación entre el costo – beneficio que estas conllevan. En el presente estudio se aborda el contexto social en el que se desarrolla la producción audiovisual en el Estado de Nayarit, la percepción de los productores audiovisuales y las condiciones socio-políticas-económicas de esta industria
Verification of stereotactic radiosurgery plans for multiple brain metastases using a virtual phantom-based procedure
Background: The purpose of this study was to describe the use of the VIPER software for patient-specific quality assurance (PSQA) of single-isocenter multitarget (SIMT) stereotactic radiosurgery (SRS) plans.
Materials and methods: Twenty clinical of intensity-modulated (IMRT) SIMT SRS plans were reviewed. A total of 88 brain metastases were included. Number of lesions per plan and their individual volumes ranged from 2 to 35 and from 0.03 to 32.8 cm3, respectively. Plans were designed with the Eclipse system, and delivered using a Varian CLINAC linac. SRS technique consisted of non-coplanar static-field sliding-window IMRT.
Each plan was mapped onto a virtual cylindrical water phantom (VCP) in the Eclipse to calculate a 3D dose distribution (verification plan). The VIPER software reconstructed the 3D dose distribution inside the VCP from the acquired in-air electronic portal image device (EPID) images of the treatment fields.
A 3D gamma analysis was used to compare the reconstructed doses to the Eclipse planned doses on the VCP. Gamma passing rates (GPRs) were calculated using 3% global/2 mm criteria and dose thresholds ranged from 10% to 90% of the maximum dose.
Results: The averages (± 1 SD) of the 3D GPRs over the 20 SRS plans were: 99.9 ± 0.2%, 99.7 ± 0.3%, 99.6 ± 0.5%, 99.3 ± 0.9%,99.1 ± 1.6%, 99.0 ± 1.6%, and 98.5 ± 3.3%, for dose thresholds of 10%, 20%, 30%, 50%, 70%, 80% and 90% respectively.
Conclusions: This work shows the feasibility of the VIPER software for PSQA of SIMT SRS plans, being a reliable alternative to commercially available 2D detector arrays
Procesos argumentativos y su relación con el aprendizaje del concepto tejido muscular
El presente trabajo, en vía de ejecución, pretende establecer relaciones entre el desarrollo de la competencia argumentativa y el aprendizaje del concepto tejido muscular. Atendiendo a esto, la investigación se desarrolla en tres momentos: diagnóstico, diseño de secuencias de actividades e intervención y valoración. Aquí se presentan los resultados de la primera fase. Los resultados muestran inicialmente, que los estudiantes se ubican en modelos conceptuales que denominamos: teoría neumática, teoría del uso y el desuso y teoría de la contracción
ZnAl hydrotalcites modified with nanocomposites nZVI–PAA for environmental remediation
Diffraction patterns of polyacrylic acid (PAA) encapsulated-(Fe)-modified ZnAl hydrotalcite (ZnAlH) showed the integration of Fe in the H lattice, resulting in a hybrid nanocomposite (Fe-PAA-ZnAlH), which was mainly verified with the characteristic shift in the 59–63° (2θ) region of the ZnAlH (110) reflection plane. The rise in the unit cell parameters (c and a) as the Fe % incremented, denoted incorporation of Fe in the ZnAlH red. Nonetheless, changes in the immobilizer molecular weight (PAA MW) from 1250 kDa to 5.1 kDa did not cause a difference in the distance between layers (c parameter) but in the cation-cation separation (a parameter), which meant that the nanoparticle was not located between layers, but in the lattice. The resulting band gap energies of the calcined hybrid nanocomposites were among 1.07–1.21 eV, which is an additional support of Fe+3 integration, suggesting insertion of Fe+3 3d orbitals between the valence and the conduction band of ZnO. Furthermore, nZVI were prepared through a pre-agglomeration reduction method, where COOH-groups were bound to metal cations. Initially, aqueous Fe+2 was bound to PAA [Fe+2-PAA], then reduced to obtain enclosed hybrid (nZVI-PAA). Less stability and more aggregation were observed with the lower molecular weight PAA. Additionally, PAA dissociation caused by pH changes affected the clustering of the nZVI particles. At higher MW, the hydrodynamic diameter and size distribution become smaller and tighter, respectively, allowing a more monodispersed population with sphere shape and organized in core–shell beads chains.Fil: Nieto Zambrano, Sorelis. Universidad de Guanajuato; MéxicoFil: Ramos Ramirez, Esthela. Universidad de Guanajuato; MéxicoFil: Tzompantzi Morales, Francisco. Universidad Autónoma Metropolitana; MéxicoFil: Boffito, Daria Camilla. No especifíca;Fil: Naccache, Rafik. Concordia University; CanadáFil: Gutiérrez Ortega, Norma L.. Universidad de Guanajuato; MéxicoFil: Litter, Marta Irene. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Cipagauta Diaz, Sandra. Universidad Autónoma Metropolitana; MéxicoFil: Barbosa López, Aida Liliana. Universidad de Cartagena.; Colombi
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