891 research outputs found

    Flora vascular y conexiones fitogeográficas de las montañas Carabaya, Perú

    Get PDF
    Studies of floristic composition and plant species richness in tropical mountains support their recognition as areas of high biological diversity, and therefore of their importance for plant conservation. Here, we present data on the flora of the high Andes of eight sites centered in the Carabaya mountains, and also provide a floristic comparison with nine other floras within Peru and northern Bolivia. The study area includes 506 species of vascular plants, grouped in 203 genera and 66 families. The highest species richness was found in two families: Asteraceae and Poaceae, which collectively encompass 37% of all species. Other important families were Caryophyllaceae, Fabaceae, Malvaceae, Brassicaceae, Caprifoliaceae, Gentianaceae, Plantaginaceae and Cyperaceae. The most diverse genera were Senecio, Calamagrostis, Poa and Nototriche. Perennial herbs were the dominant growth form. The vascular flora of the Carabaya Mountains is closely related to those of other regions of southern Peru. Also, more than half of all vascular plants registered for the Carabaya Mountain occur in the Andean region of Bolivia, which shows the undoubted geophysical and phytogeographical connection of the Carabaya and the Bolivian Apolobamba Mountains. This study also shows that there is still a need for more extensive plant collecting and future exploration, since the Carabaya, as other parts of Peru’s high Andes are subject of dramatic change that may threaten these plant populations.Los estudios sobre la composición florística y riqueza de especies en montañas tropicales apoyan su reconocimiento como áreas de alta diversidad biológica, y, por tanto, de su importancia para la conservación. En este trabajo presentamos datos sobre la flora altoandina de ocho sitios localizados en la Cordillera de Carabaya, proveemos también una comparación florística con otros nueve lugares tanto en Perú como en el norte de Bolivia. El área de estudio incluye 506 especies de plantas vasculares, reconocidas en 203 géneros y 66 familias. Las tasas más altas de riqueza de especies se hallan en dos familias: Asteraceae y Poaceae, que colectivamente abarcan el 37% de todas las especies. Otras familias importantes fueron Caryophyllaceae, Fabaceae, Malvaceae, Brassicaceae, Caprifoliaceae, Gentianaceae, Plantaginaceae y Cyperaceae. Los géneros más diversos fueron Senecio, Calamagrostis, Poa y Nototriche. La forma de crecimiento predominante fueron las hierbas perennes. La flora vascular de la Cordillera Carabaya está muy relacionada con otras regiones del sur de Perú. Además, más de la mitad de todas las plantas vasculares registradas para la Cordillera Carabaya se encuentran en la región andina de Bolivia, lo que demuestra la indudable conexión geofísica y fitogeográfica entre las cordilleras Carabaya y Apolobamba de Bolivia. Este estudio también demuestra la necesidad de una extensa colección botánica y futura exploración, desde que Carabaya, como otras partes de los altos Andes del Perú, están sujetos a cambios dramáticos que amenazan las poblaciones de esas plantas

    Passifloraceae endémicas del Perú

    Get PDF
    La familia Passifloraceae es reconocida en el Perú por presentar tres géneros y 95 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004), la mayoría bejucos y lianas. En este trabajo reconocemos 24 especies y siete taxones subespecíficos como endemismos peruanos, todas en el género Passiflora. Los taxones endémicos se encuentran principalmente en las regiones Bosques Muy Húmedos Montanos y Bosques Húmedos Premontanos, entre los 700 y 2850 m de altitud. Cinco especies endémicas se encuentran dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.The Passifloraceae are represented in Peru by three genera and 95 species (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004), mainly vines and lianas. Here we recognize as Peruvian endemics 24 species and seven infra-specific taxa, all in the genus Passiflora. These endemic taxa are found mainly in Very Humid Montane and Very Humid Premontane Forests regions, between 700 and 2850 m elevation. Five endemic taxa are recorded in the Peruvian System of Protected Natural Areas

    Observations of interplanetary dust by the Juno magnetometer investigation

    Get PDF
    One of the Juno magnetometer investigation's star cameras was configured to search for unidentified objects during Juno's transit en route to Jupiter. This camera detects and registers luminous objects to magnitude 8. Objects persisting in more than five consecutive images and moving with an apparent angular rate of between 2 and 18,000 arcsec/s were recorded. Among the objects detected were a small group of objects tracked briefly in close proximity to the spacecraft. The trajectory of these objects demonstrates that they originated on the Juno spacecraft, evidently excavated by micrometeoroid impacts on the solar arrays. The majority of detections occurred just prior to and shortly after Juno's transit of the asteroid belt. This rather novel detection technique utilizes the Juno spacecraft's prodigious 60 sq. m of solar array as a dust detector and provides valuable information on the distribution and motion of interplanetary (greater than a micron) dust. Plain Language Summary: The Juno magnetometer investigation uses star cameras co-located with the magnetic sensors at the outer end of one of Juno's solar arrays. These cameras compare images with an onboard star catalog to determine the orientation of the sensors in inertial space. They also serendipitously recorded multiple images of small particles excavated from the spacecraft by high-velocity dust impacts. We trace their trajectories back in time to demonstrate that they evolved from the spacecraft. This allows us to use the vast collecting area of Juno's solar arrays (60 sq. m)as a novel dust detector, sensitive to particles with a mass range never before measured in situ

    Autumn movements of fin whales (Balaenoptera physalus) from Svalbard, Norway, revealed by satellite tracking

    Get PDF
    Insight into animal movements is essential for understanding habitat use by individuals as well as population processes and species life-history strategies. In this study, we instrumented 25 fin whales with ARGOS satellite-transmitters in Svalbard, Norway, to study their movement patterns and behaviour (Area Restricted Search (ARS), transiting or unknown) during boreal autumn/early winter. Ten of the whales stayed in the tagging area (most northerly location: 81.68°N) for their entire tracking periods (max 45 days). The other 15 whales moved in a south-westerly direction; the longest track ended off the coast of northern Africa (> 5000 km from the tagging location) after 96 days. The whales engaged in ARS behaviour intermittently throughout their southward migrations. During transit phases the whales moved quickly; one individual maintained an average horizontal speed of 9.3 km/h (travelling 223 km per day) for a period of a week. This study documents that: (1) some fin whales might remain at high latitudes during winter; (2) the whales that do migrate probably feed along the way; (3) they can maintain high transiting speed for long periods and; (4) one breeding area for this species is likely located in deep, warm water some 100 km west of Morocco.publishedVersio

    Lost Highway Not Forgotten: Satellite Tracking of a Bowhead Whale (Balaena mysticetus) from the Critically Endangered Spitsbergen Stock

    Get PDF
    The Spitsbergen bowhead whale stock is critically endangered. It is believed to number in the tens. Here we report results from the first satellite transmitter ever deployed on an individual from this stock. A female whale was tagged on 3 April 2010 (at 79˚54' N, 01˚03' E), but no locations were transmitted by the tag until 30 April 2010, after which data were received continuously for 86 days. Additionally, three small clusters of locations were transmitted later in the year; the latest was received 20 December 2010 (262 days after deployment). During the 86 days of continuous tracking, the whale initially remained in the middle of the Fram Strait, between 77˚45' N, 5˚ W and 80˚10' N, 5˚ E. For a two-week period starting around 10 June 2010, the whale traveled southwest down to 73˚40' N (at least 950 km). Subsequently it remained at southern latitudes between ~70˚ and 73˚ N until the tag stopped continuous transmissions on 24 July. Movement patterns analyzed using first-passage times (FTP), fitted as functions of various environmental variables using Cox Proportional Hazards models, showed that the whale spent most of its time in waters close to the ice edge with modest ice coverage, over areas where the bottom slope was relatively steep. Winter positions (27 November – 20 December 2010) revealed that the whale was back in the North at about 80˚ N. This information, in combination with recent data from passive acoustic listening devices, suggests that the Spitsbergen bowhead stock overwinters at high-latitude locations. The north-south movements of this whale during summer are consistent with the patterns that early whalers described for bowhead whales in this region in the 16th and 17th centuries.La population de baleines boréales de Spitzberg est en danger critique d’extinction. L’on croit qu’elle se chiffrerait dans la dizaine. Ici, nous faisons état des résultats obtenus à l’aide du premier émetteur satellite à n’avoir jamais été installé sur un individu de cette population. Une baleine femelle a été marquée le 3 avril 2010 (à 79˚54' N, 01˚03' E), mais aucun signal n’a été transmis par ce marquage avant le 30 avril 2010, après quoi nous avons reçu des données continuelles pendant 86 jours. Plus tard dans le courant de l’année, nous avons également reçu trois petits blocs d’information, dont le dernier a été transmis le 20 décembre 2010 (262 jours après la date du marquage). Au cours des 86 jours d’information continuelle, la baleine restait d’abord au milieu du détroit de Fram, entre 77˚45' N, 5˚ O et 80˚10' N, 5˚ E. Pendant une période de deux semaines commençant vers le 10 juin 2010, la baleine s’est déplacée vers le sud-ouest jusqu’à 73˚40' N (au moins 950 km). Par la suite, elle est restée dans les latitudes du sud entre ~70˚ et 73˚ N jusqu’à ce que le marquage cesse les transmissions continuelles le 24 juillet. Les habitudes de déplacement analysées en recourant aux temps du premier passage (FTP), ajustées à titre de fonctions de diverses variables environnementales s’appuyant sur les modèles des hasards proportionnels de Cox, ont laissé entrevoir que la baleine passait la plus grande partie de son temps dans les eaux à proximité des lisières de glace dont la couverture était modeste par rapport aux endroits où la pente du fond était relativement abrupte. Les positions enregistrées en hiver (du 27 novembre au20 décembre 2010) ont révélé que la baleine était retournée dans le nord à environ 80˚ N. Cette information, alliée aux récentes données provenant d’appareils d’écoute acoustique, suggère que la population de baleines boréales de Spitzberg passe l’hiver à de hautes latitudes. Pendant l’été, les mouvements nord-sud de cette baleine sont conformes aux habitudes de déplacement de la baleine boréale, telles que décrites par les anciens baleiniers dans cette région au cours des XVIe et XVIIe siècles

    Dimethyl ether in its ground state, v=0, and lowest two torsionally excited states, v11=1 and v15=1, in the high-mass star-forming region G327.3-0.6

    Full text link
    The goal of this paper is to determine the respective importance of solid state vs. gas phase reactions for the formation of dimethyl ether. This is done by a detailed analysis of the excitation properties of the ground state and the torsionally excited states, v11=1 and v15=1, toward the high-mass star-forming region G327.3-0.6. With the Atacama Pathfinder EXperiment 12 m submillimeter telescope, we performed a spectral line survey. The observed spectrum is modeled assuming local thermal equilibrium. CH3OCH3 has been detected in the ground state, and in the torsionally excited states v11=1 and v15=1, for which lines have been detected here for the first time. The emission is modeled with an isothermal source structure as well as with a non-uniform spherical structure. For non-uniform source models one abundance jump for dimethyl ether is sufficient to fit the emission, but two components are needed for the isothermal models. This suggests that dimethyl ether is present in an extended region of the envelope and traces a non-uniform density and temperature structure. Both types of models furthermore suggest that most dimethyl ether is present in gas that is warmer than 100 K, but a smaller fraction of 5%-28% is present at temperatures between 70 and 100 K. The dimethyl ether present in this cooler gas is likely formed in the solid state, while gas phase formation probably is dominant above 100 K. Finally, the v11=1 and v15=1 torsionally excited states are easily excited under the density and temperature conditions in G327.3-0.6 and will thus very likely be detectable in other hot cores as well.Comment: 12 pages (excluding appendices), 8 figures, A&A in pres

    Seasonal variability of the warm Atlantic Water layer in the vicinity of the Greenland shelf break

    Get PDF
    The warmest water reaching the east and west coast of Greenland is found between 200?m and 600?m. Whilst important for melting Greenland's outlet glaciers, limited winter observations of this layer prohibit determination of its seasonality. To address this, temperature data from Argo profiling floats, a range of sources within the World Ocean Database and unprecedented coverage from marine-mammal borne sensors have been analysed for the period 2002-2011. A significant seasonal range in temperature (~1-2?°C) is found in the warm layer, in contrast to most of the surrounding ocean. The phase of the seasonal cycle exhibits considerable spatial variability, with the warmest water found near the eastern and southwestern shelf-break towards the end of the calendar year. High-resolution ocean model trajectory analysis suggest the timing of the arrival of the year's warmest water is a function of advection time from the subduction site in the Irminger Basin

    Prosthetic heart valve evaluation by magnetic resonance imaging

    Get PDF
    Objective: To evaluate the potential of magnetic resonance imaging (MRI) for evaluation of velocity fields downstream of prosthetic aortic valves. Furthermore, to provide comparative data from bileaflet aortic valve prostheses in vitro and in patients. Methods: A pulsatile flow loop was set up in a 7.0 Tesla MRI scanner to study fluid velocity data downstream of a 25 mm aortic bileaflet heart valve prosthesis. Three dimensional surface plots of velocity fields were displayed. In six NYHA class I patients blood velocity profiles were studied downstream of their St. Jude Medical aortic valves using a 1.5 Tesla MRI whole-body scanner. Blood velocity data were displayed as mentioned above. Results: Fluid velocity profiles obtained from in vitro studies 0.25 valve diameter downstream of the valve exhibited significant details about the cross sectional distribution of fluid velocities. This distribution completely reflected the valve design. Blood velocity profiles in humans were considerably smoother and in some cases skewed with the highest velocities toward the anterior-right ascending aortic wall. Conclusion: Display and interpretation of fluid and blood velocity data obtained downstream of prosthetic valves is feasible both in vitro and in vivo using the MRI technique. An in vitro model with a straight tube and the test valve oriented orthogonally to the long axis of the test tube does not entail fluid velocity profiles which are compatible to those obtained from humans, probably due to the much more complex human geometry, and variable alignment of the valve with the ascending aorta. With the steadily improving quality of MRI scanners this technique has significant potential for comparative in vitro and in vivo hemodynamic evaluation of heart valve
    corecore