1,789 research outputs found
Assessment of the Accuracy of a Multi-Beam LED Scanner Sensor for Measuring Olive Canopies
MDPI. CC BYCanopy characterization has become important when trying to optimize any kind of agricultural operation in high-growing crops, such as olive. Many sensors and techniques have reported satisfactory results in these approaches and in this work a 2D laser scanner was explored for measuring canopy trees in real-time conditions. The sensor was tested in both laboratory and field conditions to check its accuracy, its cone width, and its ability to characterize olive canopies in situ. The sensor was mounted on a mast and tested in laboratory conditions to check: (i) its accuracy at different measurement distances; (ii) its measurement cone width with different reflectivity targets; and (iii) the influence of the target’s density on its accuracy. The field tests involved both isolated and hedgerow orchards, in which the measurements were taken manually and with the sensor. The canopy volume was estimated with a methodology consisting of revolving or extruding the canopy contour. The sensor showed high accuracy in the laboratory test, except for the measurements performed at 1.0 m distance, with 60 mm error (6%). Otherwise, error remained below 20 mm (1% relative error). The cone width depended on the target reflectivity. The accuracy decreased with the target density
Mitochondrial inhibitors activate influx of external Ca2+ in sea urchin sperm
AbstractSea urchin sperm have a single mitochondrion which, aside from its main ATP generating function, may regulate motility, intracellular Ca2+ concentration ([Ca2+]i) and possibly the acrosome reaction (AR). We have found that acute application of agents that inhibit mitochondrial function via differing mechanisms (CCCP, a proton gradient uncoupler, antimycin, a respiratory chain inhibitor, oligomycin, a mitochondrial ATPase inhibitor and CGP37157, a Na+/Ca2+ exchange inhibitor) increases [Ca2+]i with at least two differing profiles. These increases depend on the presence of extracellular Ca2+, which indicates they involve Ca2+ uptake and not only mitochondrial Ca2+ release. The plasma membrane permeation pathways activated by the mitochondrial inhibitors are permeable to Mn2+. Store-operated Ca2+ channel (SOC) blockers (Ni2+, SKF96365 and Gd2+) and internal-store ATPase inhibitors (thapsigargin and bisphenol) antagonize Ca2+ influx induced by the mitochondrial inhibitors. The results indicate that the functional status of the sea urchin sperm mitochondrion regulates Ca2+ entry through SOCs. As neither CCCP nor dicycloexyl carbodiimide (DCCD), another mitochondrial ATPase inhibitor, eliminate the oligomycin induced increase in [Ca2+]i, apparently oligomycin also has an extra mitochondrial target
Detection of a multi-shell planetary nebula around the hot subdwarf O-type star 2MASS J19310888+4324577
(Abridged) The origin of hot subdwarf O-type stars (sdOs) remains unclear
since their discovery in 1947. Among others, a post-Asymptotic Giant Branch
(post-AGB) origin is possible for a fraction of sdOs. We are involved in a
comprehensive ongoing study to search for and to analyze planetary nebulae
(PNe) around sdOs with the aim of establishing the fraction and properties of
sdOs with a post-AGB origin. We use deep Halpha and [OIII] images of sdOs to
detect nebular emission and intermediate resolution, long-slit optical
spectroscopy of the detected nebulae and their sdO central stars. These data
are complemented with other observations for further analysis of the detected
nebulae. We report the detection of an extremely faint, complex PN around 2MASS
J19310888+4324577 (2M1931+4324), a star classified as sdO in a binary system.
The PN shows a bipolar and an elliptical shell, whose major axes are oriented
perpendicular to each other, and high-excitation structures outside the two
shells. WISE archive images show faint, extended emission at 12 and 22 microns
in the inner nebular regions. The internal nebular kinematics is consistent
with a bipolar and a cylindrical/ellipsoidal shell, in both cases with the main
axis mainly perpendicular to the line of sight. The nebular spectrum only
exhibits Halpha, Hbeta and [OIII]4959,5007 emission lines, but suggests a very
low-excitation ([OIII]/Hbeta = 1.5), in strong contrast with the absence of
low-excitation emission lines. The spectrum of 2M1931+4324 presents narrow,
ionized helium absorptions that confirm the previous sdO classification and
suggest an effective temperature >= 60000 K. The binary nature of 2M1931+4324,
its association with a complex PN, and several properties of the system provide
strong support for the idea that binary central stars are a crucial ingredient
in the formation of complex PNe.Comment: 8 pages, 7 figures, accepted in Astronomy and Astrophysic
Mining for Restriction Endonucleases in Nicaragua
The Molecular Biology Center at the University of Central America in Nicaragua (CBM-UCA) was founded in 1999 to strengthen biotechnology research capacity and education in Nicaragua and the Central American region. One of the first projects launched by the CBM-UCA was bio-prospecting for key industrial enzymes. This ongoing study seeks to discover and characterize restriction enzymes (RE) in bacteria, and to create a database of microorganisms isolated and identified by 16S rDNA sequencing methodology. In this paper we highlight the importance of studying
the extreme environmental conditions for building knowledge of Nicaraguan biodiversity through modern molecular biology techniques such as metagenomics. The isolation of prototype enzymes such as EcoRV and ClaI is presented as an update and extension of previously undertaken work
Park use, perceived park proximity, and neighborhood characteristics: Evidence from 11 cities in Latin America
This study examines how park use may be associated with perceived park proximity, neighborhood-built environment and perceived social disorder in Latin American cities. The study uses self-reported data from the 2016 CAF survey, including 7,970 urban residents from 11 cities across Latin America. Results show positive graded associations between perceived park proximity and use, holding all others constant. Additional factors that were found to be associated with park use are neighborhood formality and related built-environment characteristics, including paved streets and sidewalks. Park use was mostly unrelated to perceived social disorder, with the exception of indigence, with which it is was positively associated. Stronger associations between park proximity and use were observed among those who reported higher prevalence of indigence or begging in their household block. These findings stress the importance of perceived park proximity in enhancing their use in urban Latin America, and challenge the role of social disorder and crime as a barrier for park use
Immigració, unions mixtes i integració sociocultural : cap a una anà lisi complexa multimètode
Des de principis de la darrera dècada, coincidint amb la important arribada d'immigració estrangera a Espanya, les unions mixtes o binacionals han augmentat considerablement. Malgrat això, encara se sap ben poc sobre l'abast, les dinà miques internes, els significats i les conseqüències d'aquesta realitat. En aquest article presentem els avenços de dos projectes de recerca en curs on s'està intentant clarificar la relació entre unions/llars mixtes i integració/cohesió social, a partir de l'estudi d'unions mixtes i no mixtes de set col·lectius immigrats residents a Catalunya, aplicant una aproximació multimètode (quantitativa i qualitativa), que inclou la explotació de fonts estadÃstiques administratives i l'anà lisi de 94 xarxes personals/socials. Les dades que presentem aquà corresponen a l'anà lisi d'una de les fonts estadÃstiques més significatives (ENI) i a l'anà lisi descriptiva d'alguns casos de xarxes personals. Tot apunta a una relació entre «mixicitat» i integració multidireccional o segmentada, més complexa del que tradicionalment s'ha teoritzat.Desde principios de la última década, coincidiendo con la importante llegada de inmigración extranjera a España, las uniones mixtas o binacionales han aumentado considerablemente. Sin embargo, todavÃa se sabe muy poco sobre el alcance, las dinámicas internas, los significados y las consecuencias sociales de esta realidad. Presentamos aquà los avances de dos proyectos de investigación en curso donde se está intentando clarificar la relación entre uniones/hogares mixtos e integración/cohesión social, a partir del estudio de uniones mixtas y no mixtas de siete colectivos inmigrados residentes en Cataluña, aplicando una aproximación multimétodo que incluye la explotación de fuentes estadÃsticas administrativas y el análisis de 94 redes personales/sociales. Los datos que presentamos corresponden al análisis de una de las fuentes estadÃsticas más significativas (ENI) y al análisis descriptivo de algunos casos de redes personales. Todo apunta a una relación entre «mixicidad» e integración multidireccional o segmentada, más compleja de lo que tradicionalmente se ha teorizado.Depuis le début de la dernière décennie, qui coïncide avec l'arrivée importante de l'immigration étrangère en Espagne, les mariages mixtes ou bi-nationaux ont considérablement augmenté. Cependant, on en sait encore très peu sur la dimension, la dynamique interne, les significations et les conséquences sociales de cette réalité. Nous présentons ici les résultats de deux projets de recherche en cours, où nous tentons de clarifier la relation entre unions mixtes et intégration/cohésion sociale à partir de l'étude de sept groupes d'immigrés en unions mixtes et non-mixtes résidant en Catalogne, ainsi qu'une approche multi-méthode qui comprend l'exploitation des sources de données statistiques et l'analyse de 94 réseaux personnels/sociaux. Les données présentées ici correspondent à l'analyse de l'une des sources statistiques les plus importantes (ENI) ainsi que de l'analyse descriptive de certains cas de réseaux personnels. Tout indique une relation entre mixité et intégration multidirectionnelle ou segmentée, plus complexe que ce qui a traditionnellement été théorisé.Since the beginning of the last decade, coinciding with the arrival of a considerable number of foreign immigrants to Spain, the amount of mixed or bi-national unions has grown considerably. However, very little is still actually known about the scope, internal dynamics, meanings and social consequences of this situation. In this paper we present the preliminary findings of two research projects in progress, in which the relationship between mixed unions and social integration/cohesion is being analyzed, from the study of seven immigrant origins forming mixed and non-mixed unions residing in Catalonia (Spain), and using a multi-method approach that includes the analysis of administrative data sources and 94 personal/social networks. The data presented here correspond to the analysis of one significant data source (ENI) and the descriptive analysis of some personal networks. Our results suggest a multi-directional or segmented relationship between mixedness and social integration, which is much more complex than it has traditionally been theorized
Evaluación de la integración relacional de los inmigrantes en uniones mixtas a partir del análisis de redes personales
Desde principios de la última década el número de matrimonios mixtos ha crecido considerablemente. En este artÃculo presentamos resultados que intentan clarificar la relación entre uniones mixtas e integración social, a partir del análisis de datos primarios de entrevistas en profundidad con delineación de redes personales. Los resultados sobre composición y estructura de las redes muestran una presencia más numerosa de españoles en las redes de uniones mixtas, en gran parte familiares agregados por la pareja, que se incorporan antes y tienen más vÃnculos con otros inmigrantes. Sin embargo, el papel de la pareja española no es más central que el de la inmigrada, ni la proximidad emocional a los autóctonos es mayor en el caso de las uniones mixtas. Los análisis de dos redes particulares sugieren procesos diversos y complejos en la configuración de los entramados de relaciones en el destino.Since the beginning of the last decade the number of mixed unions has increased considerably. This study presents some findings that aim to clarify the relationship between mixed unions and social integration. Primary data have been collected through in-depth interviews with information on personal networks. Results regarding network composition and structure suggest a higher presence of Spaniards in the networks of mixed unions, mainly relatives of the native partner, who enter sooner the networks and have more links to other immigrants. However, the role of the Spanish partner is not more central than that of the immigrant partner, nor the emotional proximity to native actors is higher in the case of mixed unions. The analysis of two particular networks suggests diverse and complex processes in the confi guration of the relationships knits at destination
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