Inventory of macroalgal epiphytes on the seagrass Thalassia testudinum (Hydrocharitaceae) in Parque Nacional Cahuita, Caribbean coast of Costa Rica

Seagrass epiphytes play an important role in seagrass habitats; however, available information from Central America is scarce. The present study focuses on macroalgal epiphytes on leaves of the seagrass Thalassia testudinum in the seagrass meadows at Punta Cahuita, Caribbean coast of Costa Rica, and it is the first one of its kind in Costa Rica. A representative amount for each algal epiphyte species found was collected, preserved and identified to the lowest possible taxon. Preserved samples of each species were deposited in the Herbarium of the Universidad de Costa Rica. A total of 26 species of macroalgae were found: 15 species belonging to Rhodophyta, four to Chlorophyta, six to the class Phaeophyceae, and one diatom species which could not be identified. The present inventory reports three species that are new for the phycological flora of Costa Rica, four species are reported for the first time for the Caribbean coast of Costa Rica, and 17 are new reports for the Parque Nacional Cahuita area. Epiphyte species number might further rise if sampling efforts and the study area increased. Rev. Biol. Trop. 56 (Suppl. 4): 163-174. Epub 2009 June 30.Los epífitos de pasto marino juegan un papel impor- tante en el hábitat de pastos marinos. Sin embargo, la información disponible sobre este tema en América Central es muy limitada. Este estudio se enfoca en las macroalgas epífitas de hojas del pasto marino Thalassia testudinum en las praderas de pasto marino de Punta Cahuita, costa Caribe de Costa Rica y es el primero de su tipo para Costa Rica. Una cantidad representativa para cada especie de epífito algal encontrada se colectó, preservó e identificó al menor taxon posible. Muestras preservadas para cada especie fue- ron depositadas en el Herbario de la Universidad de Costa Rica (USJ). Se encontró un total de 26 especies de macroal- gas: 15 especies de Rhodophyta, cuatro de Chlorophyta, seis pertenecientes a la clase Phaeophyceae y una especie de diatomea que no fue posible identificar. El inventario reporta tres especies por primera vez para la flora fico- lógica de Costa Rica, cuatro especies son reportadas por primera vez para el Caribe de Costa Rica y 17 especies son nuevos reportes para el Parque Nacional Cahuita. Se comparan nuestros resultados con aquellos obtenidos en estudios similares en la región y se especula que el número de especies de epífitos podría aumentar de ser ampliado el esfuerzo de recolecta y el área de estudio.Universidad de Costa Rica/[]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de BiologíaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR

Point-contact spectroscopy of the borocarbide superconductor YNi2B2C

Point-contact (PC) spectroscopy measurements on YNi2B2C single crystals in the normal and superconducting (SC) state (T_c=15.4K) for the main crystallographic directions are reported. The PC study reveals the electron-phonon interaction (EPI) function with a dominant maximum around 12meV and a further weak structure (kink or shallow broad maximum) at higher energy at about 50meV. Other phonon maxima at 20, 24 and 32meV specified in the phonon DOS of YNi2B2C by neutron measurements [PRB, V.55, 9058 (1997)] are not resolved in the PC spectra pointing out to the main role of the low energy phonon modes in EPI. Directional study of the SC gap results in \Delta_[100]=1.5meV for the a- direction and \Delta_[001]=2.4meV along the c-axis which may point to anisotropic and/or multiband behavior. Noteworthy, the critical temperature T_c in all cases corresponds to that of bulk samples. The value 2\Delta_[001]/kT_c=3.6 is close to the BCS one of 3.52, and the temperature dependence \Delta(T) is BCS-like, while for the a-direction \Delta(T) deviates from mean-field BCS behavior above T_c/2. The directional variation in \Delta can be attributed to the multiband nature of the SC state in YNi2B2C predicted 10 years ago (PRL, V.80, 1730 (1998)).Comment: 3 figs, 2 pages, presented on M2S-HTSC Conference, July 9-14, 2006, Dresde

Adequacy of technical and commercial alternatives applied to machine tool verification using laser tracker

Besides presenting a volumetric verification technique that allows characterization of the different geometric errors of a machine tool (MT) depending on its kinematic chain and geometry through a kinematic model, this paper investigates the influence of measurement tools and techniques available on the final accuracy of the MT. Volumetric verification based on a laser tracker (LT) relates the coordinates of the tool with the coordinates of the LT, including it into the kinematic model. Using a non-lineal optimization process, approximation functions that characterize the joint influence of MT geometric errors are obtained. However, measurement data will be affected by previous compensation of the MT, the accuracy of the measurement system, LT measurement technology, the type of retroreflector used, and techniques used to improve data accuracy, among other sources of errors. This paper studies the adequacy of different commercial alternatives such as: retroreflectors, LTs from different manufacturers, etc., that can be applied in MT verification using a long-range MT. As the accuracy is strongly affected by the uncertainty of its angular encoders, the multilateration technique tries to improve data accuracy using only LT radial information. Nonetheless, a new bundle adjustment which uses radial and angular information is presented in current metrology software. This paper studies both techniques and analyzes their adequacy for MT verification too

EL EMPRESARIADO COMO FUENTE DE LA SEGREGACION POR SEXO

Este artículo presenta una parte de una amplia investigación cuyo objetivo era proponer Políticas Activas Institucionales para favorecer la inserción laboral de las mujeres en sectores o profesiones en las que estén subrepresentadas. El trabajo trata de profundizar en el comportamiento del empresariado para determinar cual es su grado de responsabilidad e influencia en la segregación sexual del mercado de trabajo. Para ello se realizó un estudio cualitativo. Los resultados nos muestran un aumento de la sensibilización. Los empresarios creen que no es justo, pero no se sienten responsables. Demandan una mayor participación del Gobierno y de la sociedad en general, a la vez que reconocen desconocer las políticas activas institucionales existentes

Independent determination of the two gaps by directional point-contact spectroscopy in MgB_2 single crystals

Directional point-contact spectroscopy measurements were performed for the first time in state-of-the-art MgB_2 single crystals. The selective suppression of the superconductivity in the "pi" band by means of a suitable magnetic field allowed separating the partial contribution of each band to the total point-contact conductance. By fitting the partial conductance curves sigma_sigma(V) and sigma_pi(V), we got an independent determination of the two gaps, Delta_sigma and Delta_pi, with a strong reduction of the experimental uncertainty. Their temperature dependence was found to agree well with the predictions of the two-band models for MgB_2.Comment: 6 pages, 4 eps figures. References added, abstract rewritten, text slightly changed. Proceedings of the BOROMAG Conference, June 17-19, Genoa, Ital

Peritoneal tuberculosis due to Mycobacterium caprae

The incidence of tuberculosis in humans due to Mycobacterium caprae is very low and is almost confined to Europe. We report a case of a previously healthy 41-year-old Moroccan with a 6 month history of abdominal pain, weight loss, fatigue and diarrhea. A diagnosis of peritoneal tuberculosis due to M. caprae was mad