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Search Results: 1 - 10 of 23 matches for " Davinia "
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Is there a direct role for erythrocytes in the immune response?
Davinia Morera, Simon A MacKenzie
Veterinary Research , 2011, DOI: 10.1186/1297-9716-42-89
Abstract: 1. Introduction2. Erythrocyte-pathogen interaction3. Immunity4. Insights from genomic and proteomic studies5. Future directions6. Competing interests7. Authors' contributions8. Acknowledgements9. ReferencesIn all vertebrates, blood is composed of cells and plasma protein (90% in volume is water). By far the most abundant cell type in circulation is the erythrocyte, present in the nucleated form in the majority of vertebrates with the notable exception of the mammals. All vertebrates also have distinct populations of circulating leukocytes and non-mammalian vertebrates have nucleated thrombocytes instead of platelets. Erythrocytes are generally characterized as oval in shape and their characteristic red color is due to the respiratory globin pigments including the hemoglobins, the most abundant protein in these cells. All non-mammalian (birds, reptiles, amphibians and fish) erythrocytes with a few isolated exceptions are nucleated and contain organelles in their cytoplasm [1]. Erythrocyte longevity varies across the major vertebrate groups where in humans the cellular half life of erythrocytes is about 120 days and is about 40, 600-800, 300-1400 and 80-500 days in birds, reptiles, amphibians and fish respectively [1-5]. Furthermore and with a direct relationship to longevity, different maturation states are observed in the circulating erythrocytes of non-mammalian species including; changes in cytoplasmatic shape, staining, nuclear size and chromatin density. Total RNA and organelles content follow an inverse relationship with cellular age where young red blood cells contain a higher total concentration of RNA and aging cells display a loss of cellular organelles including ribosomes and mitochondria [6]. Interestingly, in endothermic species cellular longevity is similar indicative of a parallel evolutionary trend toward respiratory specialization linked in parallel to increased metabolic demand. However in view of the vast diversity of vertebrate species where the e
Datación por ESR del yacimiento arqueológico del Pleistoceno inferior de Vallparadís (Terrassa, Catalu a, Espa a)
Duval, Mathieu,Moreno, Davinia,Shao, Qingfeng,Voinchet, Pierre
Trabajos de Prehistoria , 2011, DOI: 10.3989/tp.2011.11056
Abstract: Excavated between 2005 and 2007, the site of Vallparadís (Terrassa, Spain) has given an abundant and diversified fauna associated with a rich Mode 1 industry. In order to complete the chronostratigraphic framework, we performed ESR and combined US-ESR dating applied to quartz grains extracted from sediments and fossil teeth, respectively. The results obtained are very significant, giving a weighted mean ESR age of 0.83 ± 0.13 Ma (2σ) for the reference archaeological level of the site (level 10) and another of 0.79 ± 0.23 Ma (2σ) for the archaeological level 12 of the Vallparadís sequence. These ESR results are in total agreement with the ones derived from biochronology and paleomagnetism. This whole dataset allows the elaboration of a reliable and consistent chronostratigraphic framework which chronologically places Vallparadís site in the late Early Pleistocene period, i.e. within a time range comprised between Jaramillo and Brunhes geomagnetic events. Consequently, as well as Gran Dolina-TD6 and Sima del Elefante- TE9 sites, in Atapuerca, Burgos, Vallparadís can be therefore considered as a key site for the study of early hominid settlements in Europe. Excavado entre 2005 y 2007, el yacimiento de Vallparadís (Terrassa, Espa a) ha aportado una fauna rica y diversa en asociación con un importante conjunto lítico de Modo 1. Con el objetivo de completar el marco cronoestratigráfico, se hicieron dataciones por los métodos de Resonancia Paramagnética Electrónica (Electron Spin Resonance, ESR) y ESR combinada con uranio-torio sobre algunas muestras de granos de cuarzo extraídos de sedimentos y dientes fósiles, respectivamente. Los resultados obtenidos son muy significativos, ofreciendo edades ESR promedias de 0,83 ± 0,13 Ma (2σ) para el nivel arqueológico de referencia del yacimiento (nivel 10) y de 0,79 ± 0,23 Ma (2σ) para el nivel arqueológico 12 de la secuencia de Vallparadís. Dichos resultados por ESR concuerdan con los obtenidos a partir de la biocronología y del paleomagnetismo. El yacimiento de Vallparadís dispone ahora de un marco cronoestratigráfico fiable y coherente, que permite situarlo cronológicamente a finales del Pleistoceno inferior, dentro de un rango temporal comprendido entre los eventos geomagnéticos de Jaramillo y Brunhes. Dicho yacimiento junto a los de Gran Dolina TD-6 y Sima del Elefante TE-9, en Atapuerca, Burgos, se posiciona como un yacimiento clave para el estudio de los primeros poblamientos humanos de Europa.
Indicadores para la evaluación de las instituciones universitarias: validación a través del método Delphi
García-Aracil, Adela,Palomares-Montero, Davinia
Revista Espa?ola de Documentación Científica , 2012,
Abstract: The evaluation of higher education activities is complex given their multiple objectives, which focus activities on the three principal academic missions of teaching, research and knowledge transfer. Various methodologies using indicators for the evaluation of universities have been proposed in the professional literature and there is intense debate over which are the most appropriate. Therefore, it is necessary to establish criteria against which to judge the existing indicators. This paper contributes directly to both theory and practice by providing a list of prioritized critical indicators for the evaluation of higher education institutions. For that purpose, we use the Delphi technique to try to achieve some sort of consensus among a group of experts with in-depth knowledge of higher education evaluation. Our results show that among the panel of experts there is no consensus and no clear cut division on the identification of which indicators are the most effective for the evaluation of university missions, the type of indicator and their degree of importance in the evaluation process. Evaluar el desempe o de las universidades es complicado ya que se trata de una institución multidimensional que desarrolla numerosas actividades en base a sus tres principales misiones: docencia, investigación y transferencia de conocimiento. En este contexto, diversas metodologías de evaluación de las universidades han sido propuestas en base al uso de indicadores, existiendo intensos debates acerca de qué indicadores son los más apropiados. Esta situación hace que resulte indispensable sistematizar la diversidad de indicadores para obtener una evaluación más rigurosa de las instituciones universitarias. El presente trabajo profundiza en esta cuestión, identificando un listado de indicadores relacionados con la evaluación de las universidades. El sistema de indicadores propuesto ha sido validado a través del método Delphi que ha permitido alcanzar cierto consenso entre los expertos participantes. La identificación realizada sirve de ayuda para tomar decisiones en torno a qué indicadores deben ser incluidos en los modelos de evaluación universitaria. Sin embargo, los resultados del estudio ponen de manifiesto que entre los gestores universitarios continúa habiendo discrepancias en cuanto a la identificación de los indicadores tanto a qué misión representan como en su tipología y grado de importancia.
Minimal exhaled nitric oxide production in the lower respiratory tract of healthy children aged 2 to 7 years
Al-Ayed Tareq,Withington Davinia,Davis G
Annals of Saudi Medicine , 2005,
Abstract: BACKGROUND : Exhaled nitric oxide (eNO) is elevated in inflammatory airway conditions, e.g. asthma. We measured eNO levels in normal preschool children for whom there is little data available and in whom the prevalence of asthma is high. SUBJECTS AND METHODS : Fifty children, 2-7 years old, undergoing elective surgery, excluding airway procedures, were recruited. Children with known respiratory disease or acute viral infections were excluded. Gas for eNO measurement was collected in a non-diffusion bag via 1) the mask after inhalation induction of anesthesia, 2) endotreacheal tube (ETT) or laryngeal mask airway (LMA), and 3) during emergence. Measurement was off-line by chemiluminescent analyzer. RESULTS : Mean eNO level by mask was 10.23 ppb (mean value±SD of 8.8-11.1 ppb) after induction and 8.35 ppb (mean value±SD of 5.9-10.8 ppb) on emergence. Mean eNO for the intubated group (n=25) was 0.75 ppb (mean value(SD of 0.4-1 ppb) ( P < 0.0001 vs mask); mean eNO for the LMA group (n=25) was 2.6 ppb (mean value±SD of 2-3.2 ppb), which differed from the mask ( P < 0.0001), and from ETT values ( P < 0.0001). CONCLUSIONS : Most eNO is produced by the upper airway in healthy pre-school children. The lower airway constitutive eNO production is very low. The LMA does not completely isolate the upper airway and current mask collection techniques allow significant contamination of samples by sino-nasal eNO production in young children.
The Clinical Utility of fMRI for Identifying Covert Awareness in the Vegetative State: A Comparison of Sensitivity between 3T and 1.5T
Davinia Fernández-Espejo, Loretta Norton, Adrian M. Owen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095082
Abstract: In the last few years, mental imagery fMRI paradigms have been used successfully to identify covert command-following and awareness in some patients who are thought to be entirely vegetative. However, to date there is only evidence supporting their use at magnetic fields of 3T, which limits their applicability in clinical settings where lower field strengths are typically used. Here, we test the ‘gold standard’ fMRI paradigm for detecting residual awareness in non-responsive patients by comparing its sensitivity at 1.5T and 3T in the same group of healthy volunteers. We were able to successfully detect brain activity showing command-following in most participants at both 3T and 1.5T, with similar reliability. These results demonstrate that fMRI assessment of covert awareness is clinically viable and therefore justify a broader use of these methods in standard assessments in severely brain injured patients.
Screening for Coping Style Increases the Power of Gene Expression Studies
Simon MacKenzie, Laia Ribas, Maciej Pilarczyk, Davinia Morera Capdevila, Sunil Kadri, Felicity A. Huntingford
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005314
Abstract: Background Individuals of many vertebrate species show different stress coping styles and these have a striking influence on how gene expression shifts in response to a variety of challenges. Principal Findings This is clearly illustrated by a study in which common carp displaying behavioural predictors of different coping styles (characterised by a proactive, adrenaline-based or a reactive, cortisol-based response) were subjected to inflammatory challenge and specific gene transcripts measured in individual brains. Proactive and reactive fish differed in baseline gene expression and also showed diametrically opposite responses to the challenge for 80% of the genes investigated. Significance Incorporating coping style as an explanatory variable can account for some the unexplained variation that is common in gene expression studies, can uncover important effects that would otherwise have passed unnoticed and greatly enhances the interpretive value of gene expression data.
Characterization of a Low-Cost Optical Flow Sensor When Using an External Laser as a Direct Illumination Source
Davinia Font,Marcel Tresanchez,Tomàs Pallejà,Mercè Teixidó,Jordi Palacín
Sensors , 2011, DOI: 10.3390/s111211856
Abstract: In this paper, a low cost optical flow sensor is combined with an external laser device to measure surface displacements and mechanical oscillations. The measurement system is based on applying coherent light to a diffuser surface and using an optical flow sensor to analyze the reflected and transferred light to estimate the displacement of the surface or the laser spot. This work is focused on the characterization of this measurement system, which can have the optical flow sensor placed at different angles and distances from the diffuser surface. The results have shown that the displacement of the diffuser surface is badly estimated when the optical mouse sensor is placed in front of the diffuser surface (angular orientation >150°) while the highest sensitivity is obtained when the sensor is located behind the diffuser surface and on the axis of the laser source (angular orientation 0°). In this case, the coefficient of determination of the measured displacement, R2, was very high (>0.99) with a relative error of less than 1.29%. Increasing the distance between the surface and the sensor also increased the sensitivity which increases linearly, R2 = 0.99. Finally, this measurement setup was proposed to measure very low frequency mechanical oscillations applied to the laser device, up to 0.01 Hz in this work. The results have shown that increasing the distance between the surface and the optical flow sensor also increases the sensitivity and the measurement range.
Design and Implementation of a Biomimetic Turtle Hydrofoil for an Autonomous Underwater Vehicle
Davinia Font,Marcel Tresanchez,Cedric Siegentahler,Tomàs Pallejà,Mercè Teixidó,Cedric Pradalier,Jordi Palacin
Sensors , 2011, DOI: 10.3390/s111211168
Abstract: This paper presents the design and implementation of a turtle hydrofoil for an Autonomous Underwater Vehicle (AUV). The final design of the AUV must have navigation performance like a turtle, which has also been the biomimetic inspiration for the design of the hydrofoil and propulsion system. The hydrofoil design is based on a National Advisory Committee for Aeronautics (NACA) 0014 hydrodynamic profile. During the design stage, four different propulsion systems were compared in terms of propulsion path, compactness, sealing and required power. The final implementation is based on a ball-and-socket mechanism because it is very compact and provides three degrees of freedom (DoF) to the hydrofoil with very few restrictions on the propulsion path. The propulsion obtained with the final implementation of the hydrofoil has been empirically evaluated in a water channel comparing different motion strategies. The results obtained have confirmed that the proposed turtle hydrofoil controlled with a mechanism with three DoF generates can be used in the future implementation of the planned AUV.
Two-Dimensional Radial Laser Scanning for Circular Marker Detection and External Mobile Robot Tracking
Mercè Teixidó,Tomàs Pallejà,Davinia Font,Marcel Tresanchez,Javier Moreno,Jordi Palacín
Sensors , 2012, DOI: 10.3390/s121216482
Abstract: This paper presents the use of an external fixed two-dimensional laser scanner to detect cylindrical targets attached to moving devices, such as a mobile robot. This proposal is based on the detection of circular markers in the raw data provided by the laser scanner by applying an algorithm for outlier avoidance and a least-squares circular fitting. Some experiments have been developed to empirically validate the proposal with different cylindrical targets in order to estimate the location and tracking errors achieved, which are generally less than 20 mm in the area covered by the laser sensor. As a result of the validation experiments, several error maps have been obtained in order to give an estimate of the uncertainty of any location computed. This proposal has been validated with a medium-sized mobile robot with an attached cylindrical target (diameter 200 mm). The trajectory of the mobile robot was estimated with an average location error of less than 15 mm, and the real location error in each individual circular fitting was similar to the error estimated with the obtained error maps. The radial area covered in this validation experiment was up to 10 m, a value that depends on the radius of the cylindrical target and the radial density of the distance range points provided by the laser scanner but this area can be increased by combining the information of additional external laser scanners.
Definition of Linear Color Models in the RGB Vector Color Space to Detect Red Peaches in Orchard Images Taken under Natural Illumination
Mercè Teixidó,Davinia Font,Tomàs Pallejà,Marcel Tresanchez,Miquel Nogués,Jordi Palacín
Sensors , 2012, DOI: 10.3390/s120607701
Abstract: This work proposes the detection of red peaches in orchard images based on the definition of different linear color models in the RGB vector color space. The classification and segmentation of the pixels of the image is then performed by comparing the color distance from each pixel to the different previously defined linear color models. The methodology proposed has been tested with images obtained in a real orchard under natural light. The peach variety in the orchard was the paraguayo (Prunus persica var. platycarpa) peach with red skin. The segmentation results showed that the area of the red peaches in the images was detected with an average error of 11.6%; 19.7% in the case of bright illumination; 8.2% in the case of low illumination; 8.6% for occlusion up to 33%; 12.2% in the case of occlusion between 34 and 66%; and 23% for occlusion above 66%. Finally, a methodology was proposed to estimate the diameter of the fruits based on an ellipsoidal fitting. A first diameter was obtained by using all the contour pixels and a second diameter was obtained by rejecting some pixels of the contour. This approach enables a rough estimate of the fruit occlusion percentage range by comparing the two diameter estimates.
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