661 research outputs found
Multi-Sensor System For Level Measurements With Optical Fibres
A system for measuring liquid level in multiple tanks using optical fibre technology has been developed. The oil field service industry can benefit from this intrinsically safe technology. Plastic optical fibre (POF) sensor heads are excited by a 650 nm laser. Laser diodes are housed in ST connectors to obtain compact and rough prototypes and these connectors are also used in the fibre pigtails. Optical multiplexing is used to increase the measuring safety area. POF splitters and connectors are used to combine all the receiving sensor head fibres in a single one. Frequency division multiplexing is used to address each sensor head. The global system is controlled through a user friendly software application running in a PC connected to the system via an RS-232 port. A scalable prototype with a range greater than 2 meter, good linearity, better than 1.5% FS (full scale), high accuracy and resolution is developed using a unique lens to collimate and focus the light. Measurements are taken to validate the designs. Up to 8 sensor heads can be connected in the present implementation. But a greater number of sensors can be allocated with minor modifications in the electronics.Universidad Carlos III de MadridPublicad
Numerical modelling of oocytes partially covered by magnetic nanoparticles in external magnetic fields
Nanorep® is a novel device based on the magnetic tweezer concept that has been
developed for precise, fast, and non-aggressive oocytes and embryos manipulation. To
operate the reproductive cells, they are first immersed in a standard host medium with
ferrite containing nanoparticles. The magnetic particles are attached to the external
matrix of the oocytes/embryos thanks to a linked protein making possible to control
them by using external magnetic fields. Electron microscope photographs show
magnetic particle aggregates around the oocyte. The total mass and distribution of the
attached magnetic particles per oocyte show a wide range of variability, which strongly
affects their magnetic response. Despite the uncertainties on the attachment of
magnetic nanoparticles, the set formed by the oocyte and the nanoparticles can be
caught and transported by using standard neodymium magnets.
Here we present an initial study of the interaction between the set
oocyte/nanoparticles and the external magnetic field in aqueous environment. We are
going to discuss several relevant topics of the model such us the characterization of
magnetic field produced by cylindrical neodymium magnets, the model of the ferrite
magnetization as an effective spherical dipole or a magnetized spherical shell, the
measurement processes to obtain the temporal evolution of the particle position and
the different observed dynamic behaviours
Density and reproductive characteristics of female brown bears in the Cantabrian Mountains, NW Spain
Here we present annual nearest-neighbour distances (as a proxy of density) between females with cubs-of-the-year (hereafter FCOY) and reproductive characteristics of brown bears Ursus arctos in the Cantabrian Mountains (NW Spain), from 1989 to 2017. FCOY nearest-neighbour distances and reproduction parameters of 19 focal females followed over several consecutive years (from 2004 to 2017) were obtained from bears inhabiting the western sector of the Cantabrian Mountains, where most of the bear population resides. In contrast, general reproductive characteristics were studied in the whole Cantabrian Mountains (western and eastern sectors together) on a sample of 362 litter sizes and 695 cubs. Mean nearest-neighbour distance between FCOY was 2559 ± 1222 m (range = 1305–4757 m). Mean litter size was significantly larger in the west (1.8 ± 0.2 cubs) than in the east (1.3 ± 0.6 cubs). Mean litter size for the whole of the Cantabrian Mountains was 1.6 ± 0.3 cubs. Litter sizes of one, two and three cubs represented 33.4, 56.1 and 10.5% of observed family groups, respectively. Interannual variations in litter size were not significant for both the western and the eastern areas. Mean cub mortality was 0.2 ± 0.5 cubs and did not vary among years. Cub mortality per litter size was 3.9% for one cub, 69.2% for two cubs and 26.9% for three cubs. Mean reproductive rate of the 19 focal females was 1.5 ± 0.6 cubs (n = 58 litters). Litter size of focal FCOY did not differ from the litter size obtained from systematic observations in the whole Cantabrian Mountains. During this period, cub mortality occurred in 24.1% of the 58 litters. Females usually bred every second year (average litter interval = 2.2 years). The estimated reproductive rate for the bear population was 0.7 young born/year/reproductive adult female
Sensores con fibra óptica de plástico para la medida remota de nivel
4 págs, 9 figs.-- Presentado en: 3ª Reunión Española de Optoelectrónica (OPTOEL'03), Leganés (Madrid), 14-16 julio 2003.La industria demanda cada vez más métodos de
medida que sean intrínsecamente seguros para aplicarlos en entornos industriales, como pueden ser atmósferas inflamables; y que eviten, en la medida de lo posible, el daño ecológico. Por ejemplo, en muchas gasolineras la necesidad de rellenar los depósitos de combustible se fija mediante control visual. Sin embargo, mientras el tanque permanece abierto se emiten a la atmósfera compuestos orgánicos volátiles (COV) que perjudican tanto la capa de ozono como la salud del operario que realiza la
comprobación. La emisión de este tipo de compuestos constituyó en el año 1998 el 20% de la emisión total de contaminantes. En la actualidad, países como Méjico financian el desarrollo e instalación de dispositivos
electrónicos para evitar los problemas mencionados anteriormente.En nuestro grupo se ha desarrollado un sistema multisensor para medida de nivel que se basa en el empleo de fibra óptica de plástico (FOP) en la cabeza sensora y como medio de transmisión en la red óptica. Se
pueden tomar medidas en varios tanques o distintos puntos en un mismo tanque, utilizando multiplexación por división de frecuencia y acopladores direccionales de
fibra óptica. En esta contribución se discute el principio de funcionamiento de dicho sensor y, a partir del modelo propuesto, se estudia la influencia que sobre la respuesta del sensor tiene la modificación de diferentes parámetros de la cabeza sensora, buscando aquellas
configuraciones que permitan optimizar la respuesta del sensor. En primer lugar se describen brevemente los distintos bloques del sensor para pasar a presentar el modelo y su discusión.Este trabajo ha sido financiado por la
Comunidad de Madrid (CAM-07T-0011-2001).Publicad
Tolerance analysis for efficient MMI devices in silicon photonics
The proceeding at: IX Conference Silicon Photonics, took place at 2014, March, 8 in S. Francisco (USA).Silicon is considered a promising platform for photonic integrated circuits as they can be fabricated in state-of-the-art electronics foundaries with integrated CMOS electronics. While much of the existing work on CMOS photonics has used directional couplers for power splitting, multimode interference (MMI) devices may have relaxed fabrication requirements and smaller footprints, potentially energy efficient designs. They have already been used as 1x2 splitters, 2x1 combiners in Quadrature Phase Shift Keying modulators, and 3-dB couplers among others. In this work, 3-dB, butterfly and cross MMI couplers are realized on bulk CMOS technology. Footprints from around 40um2 to 200 um2 are obtained. MMI tolerances to manufacturing process and bandwidth are analyzed and tested showing the robustness of the MMI devices.This work has been sponsored by the Spanish institutions Ministerio de Economía y Competitividad under project TEC2012-37983-C03-02, and grant EEBB-1-13-07511, Ministerio de Educación under grant PRX12/00007 and Fundación Caja Madrid.Publicad
Study of Fucoidans as Natural Biomolecules for Therapeutical Applications in Osteoarthritis
[Abstract]
Osteoarthritis (OA) is the most prevalent articular chronic disease. Although, to date there is no cure for OA. Fucoidans, one of the main therapeutic components of brown algae, have emerged as promising molecules in OA treatment. However, the variability between fucoidans makes difficult the pursuit of the most suitable candidate to target specific pathological processes. By an in vitro experimental approach in chondrocytes and fibroblast-like synoviocytes, we observed that chemical composition of fucoidan, and specifically the phlorotannin content and the ratio sulfate:fucose, seems critically relevant for its biological activity. Nonetheless, other factors like concentration and molecular weight of the fucoidan may influence on its beneficial effects. Additionally, a cell-type dependent response was also detected. Thus, our results shed light on the potential use of fucoidans as natural molecules in the treatment of key pathological processes in the joint that favor the development of rheumatic disorders as OA.Xunta de Galicia; ED431G2019/0
La precariedad laboral
[ES] Se analizan los fundamentos teóricos y metodológicos para la comprensión del fenómeno de la precariedad laboral y se revisa la precariedad laboral en España a partir de un análisis cuantitativo de los datos
Compromiso laboral
[ES] Se analiza el compromiso de las personas asalariadas con los valores y los objetivos empresariales comenzando con una revisión del concepto en la literatura y de los determinantes que influyen en los distintos tipos de compromiso laboral de las personas asalariadas (compromiso afectivo, compromiso de continuidad y compromiso normativo ). Se finaliza con un diagnóstico del compromiso laboral en España basado en el análisis de diversos datos
Caprellid assemblages (Crustacea: Amphipoda) in shallow waters invaded by Caulerpa racemosa var. cylindracea from southeastern Spain
Growth of the invasive algae Caulerpa racemosa var. cylindracea in shallow habitats may inXuence the
faunal assemblage composition. We studied its eVects on
caprellid assemblages associated with shallow-water habitats of hard and soft bottoms from the SE Iberian Peninsula
(native rocky-bottom algae, C. racemosa from hard and
soft bottoms, and Caulerpa prolifera, Cymodocea nodosa
and Posidonia oceanica from soft bottoms). Samples were
taken in two diVerent sampling periods (September 2004
and March 2005). A total of seven caprellid species were
identiWed, with important diVerences in their distribution in
diVerent habitats. Total abundance of caprellids was very
high in March on native algae on hard bottoms, and on
C. racemosa on both soft and hard bottoms. On both hard
and soft bottoms, abundances of Caprella hirsuta recorded
from C. racemosa were low. On the other hand, a higher
abundance of other species, namely C. acanthifera, C. santosrosai, Phtisica marina and Pseudoprotella phasma, was
recorded from C. racemosa. The results indicate that
C. racemosa may have a positive inXuence on some caprellid species, while seasonal changes are also evident. It is
concluded that introduced C. racemosa may serve as a new
habitat, promoting and maintaining caprellid populations in
shallow Mediterranean habitats.Ministerio de Educación y Ciencia de España y fondos FEDER de la Unión Europea. CGL2007-60044/BOSConsejería de Innovación, Ciencia y Empresa de la Junta de Andalucía. P07-RNM-0252
Biocompatibility and osseointegration study of new prosthetic materials
Objetivos
Los implantes óseos son utilizados cada vez con mayor frecuencia en la práctica clínica y, entre los materiales, el Ti o sus aleaciones son los de mejor rendimiento por sus propiedades fisicoquímicas. Aleaciones como TiNbTa han demostrado mejorar las características biomecánicas del Ti puro comercial (c.p.), sin embargo, su capacidad osteointegradora necesita ser evaluada. El objetivo del presente estudio fue valorar la citotoxicidad y la capacidad de adhesión, proliferación y diferenciación de células osteoblásticas en cultivo, influida por discos de material TiNbTa frente a Ti c.p.
Material y métodos
Analizamos a los 4 y 7 días del cultivo la línea celular MC3T3, la viabilidad celular (AlamarBlue Cell Viability Reagent. Invitrogen, España), así como la proliferación y diferenciación celular (actividad de fosfatasa alcalina (ALP) y microscopía electrónica de barrido (Fijación para SEM). Se realizó la prueba t de Student para determinar diferencias estadísticamente significativas entre los dos grupos de discos de estudio.
Resultados
Los resultados obtenidos demuestran muy buena viabilidad celular durante el periodo de estudio, sin diferencias significativas para ambos materiales. Así mismo, detectamos una caída en los niveles de ALP que fue significativa para ambos componentes entre los días 4 y 7 del estudio (p<0,05). Las imágenes de microscopía electrónica revelaron buena capacidad de adhesión al material, así como diferenciación celular frente a ambos tipos de discos.
Conclusiones
La aleación de TiNbTa como material para implantes óseos cuenta con una buena capacidad osteointegradora, además de resolver problemas de biomecánica que presenta el titanio puro como componente.Objetive
Bone implants are increasingly used in clinical practice and, among the materials, Ti or its alloys are offer the best performance given their physicochemical properties. Alloys such as TiNbTa have been shown to improve the biomechanical characteristics of commercial pure Ti (c.p.), however, its osseointegration capacity needs to be evaluated. The objective of the present study was to assess the cytotoxicity and the adhesion, proliferation and differentiation capacity of osteoblastic cells in culture, influenced by discs of TiNbTa material versus Ti c.p.
Material and methods
At 4 and 7 days after culture, we analyzed the MC3T3 cell line, cell viability (AlamarBlue Cell Viability Reagent. Invitrogen, Spain), as well as cell proliferation and differentiation (alkaline phosphatase activity (ALP) and scanning electron microscopy (Fixation for SEM) Student's t test was performed to determine statistically significant differences between the two groups of study discs.
Results
The results obtained show very good cell viability during the study period, with no significant differences for both materials. Likewise, we detected a drop in ALP levels that was significant for both components between days 4 and 7 of the study (p <0.05). Electron microscopy images revealed good adhesion capacity to the material, as well as cell differentiation against both types of discs.
Conclusions
The TiNbTa alloy as a material for bone implants offers good osseointegrative capacity, in addition to solving biomechanical problems that pure titanium presents as a component
- …