Karyological investigations on several species of genus Rebutia Sect. Digitorebutia (Cactaceae)

Abstract These are the first avaiable data about the karyology of the taxa belonging to Rebutia Sect. Digitorebutia, the section of genus Rebutia K. Schum. with more species. Eight species of Sect. Digitorebutia were investigated. Out of the species studied, seven (R. pygmaea, R. raulii, R. steinmannii, R. major, R. diersiana, R. haagei and R. gavazzii) are polyploid, with tetraploid chromosome number 2n=4x = 44, and one (R. leucanthema) is diploid, with chromosome number 2n=2x = 22; x = 11. This is the first karyotype information of all the species investigated

The Imaging X-ray Polarimetry Explorer (IXPE): Technical Overview

The Imaging X-ray Polarimetry Explorer (IXPE) will expand the information space for study of cosmic sources, by adding linear polarization to the properties (time, energy, and position) observed in x-ray astronomy. Selected in 2017 January as a NASA Astrophysics Small Explorer (SMEX) mission, IXPE will be launched into an equatorial orbit in 2021. The IXPE mission will provide scientifically meaningful measurements of the x-ray polarization of a few dozen sources in the 2-8 keV band, including polarization maps of several x-ray-bright extended sources and phase-resolved polarimetry of many bright pulsating x-ray sources

Il tricoma di Tillandsia L. Bromeliaceae: utilita' tassonomica e individuazione di tipi ecologici

Dottorato di ricerca in biosistematica ed ecologia vegetale. 12. cicloConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

A new quantitative classification of ecological types in the bromeliad genus Tillandsia (Bromeliaceae) based on trichomes

Using collection specimens, we measured the density and wing area of trichomes in 37 species of the bromeliad genus Tillandsia, specifically the abaxial proximal, abaxial distal, adaxial proximal and adaxial distal parts of the leaf. The product of the trichome "wing" area by the number of trichomes (means) produced a pure number (T) that was correlated to ecological features. The correlation was positive with respect to arid environments (xeric Tillands) and negative with respect to humid environments (mesic Tillands). Bulbous, and particularly myrmecophytic species and species with tanks, represented particular categories. Other intermediate types were identified based on the T number, totalling five ecological types. In comparison with other systems of ecological typification for Tillands and other Bromeliaceae, the present system offers measurable data whose analysis is reproducible. Rev. Biol. Trop. 56 (1): 191-203. Epub 2008 March 31.<br>Medimos el número por milímetro cuadrado y el área del "ala" (parte móvil) de los tricomas en las partes adaxial próxima y distal, y adaxial próxima y distal, de la hoja de 37 especies de bromelias del género Tillandsia. El producto del área del ala para el número de los tricomas (promedio) produjo un número puro (T). Hallamos que T se correlaciona con las características ecológicas de las tilandsias investigadas. La correlación es positiva con respecto a ambientes áridos (especies xéricas) y negativa con respecto a los ambientes húmedos (especies mésicas). Las especies con bulbo, y particularmente las asociadas con hormigas y especies con de tanque representan categorías particulares. Identificamos otros tipos intermedios, agradando así cinco tipos ecológicos. En comparación con otros sistemas de tipificación ecológica, este sistema ofrece la ventaja de ser reproducible y cuantitativo

The use of tropical bromeliads (Tillandsia spp.) for monitoring

The results of an experiment with two species of epiphytic angiosperms (Tillandsia caput-medusae and T. bulbosa) for monitoring polycyclic aromatic hydrocarbons (PAHs) in the air of Florence, Italy, are presented. PAHs are compounds known to be dangerous because of their carcinogenic potential, and among cormophytes, tillands (monocotyledons equipped with peculiar, specialised, epidermal trichomes) are considered promising for air pollution biomonitoring. PAHs data were obtained using GC/MS analysis of plant extracts. Analytical data indicated an increasing trend in time of PAHs bioaccumulation. This result was compared with instrumentally recorded parameters such as meteorological (rain) and environmental ones (PM10), indicating that trichome-operated physical capture of aerial particles was prominent in PAHs bioaccumulation on tillands. SEM (scanning electron microscope) observations confirmed the role of the trichomes. This work indicates that tillands are particularly useful, low-cost, biomonitoring organisms inside their area of distribution (all Latin American countries and southern USA) where these plants are easily available, but also wherever the climate allows them to survive.Se presentan los resultados de un experimento con dos especies de angiospermas epífitas (Tillandsia caputmedusae y T. bulbosa) para monitorear hidrocarbonos aromáticos policíclicos (PAHs) en el aire de Florencia, Italia. Los PAHs son compuestos que se sabe son peligrosos por su potencial carcinogénico, y, entre las cormófitas, las tilandsias (monocotiledóneas equipadas con tricomas epidérmicos, especializados y peculiares) son consideradas promisorias para el biomonitoreo de la contaminación del aire. Se obtuvieron datos de PAHs usando el análisis de GC/MS de extractos de plantas. Los datos analíticos indicaron una tendencia creciente de la bioacumulación de PAH’s en el tiempo. Este resultado se comparó con los parámetros registrados instrumentalmente como los meteorológicos (lluvia) y los ambientales (PM10), indicando que la captura física de partículas aéreas por medio de tricomas era prominente en la bioacumulación de PAHs en las tilandsias. Las observaciones de SEM (microscopio electrónico de barrido) confirmaron el papel de los tricomas. Este trabajo indica que las tilandsias son organismos de biomonitoreo, de bajo costo y particularmente útiles dentro de su área de distribución (todos los países Latinoamericanos y el sureste de EUA) donde estas plantas son disponibles fácilmente, pero también donde el clima les permite sobrevivi

L'OVI e lo sviluppo delle discipline: la filologia

Il contributo mette in luce i positivi apporti dell\u2019Opera del Vocabolario ai progressi della filologia italiana dell\u2019ultimo trentennio. Sono evidenziati elementi di continuit\ue0 tra la riflessione scientifica sorta intorno alla quinta Crusca da una parte e il dibattito critico che ha accompagnato la messa in cantiere del nuovo Vocabolario storico dall\u2019altra. Particolare rilievo assumono le intuizioni teoriche di d\u2019Arco Silvio Avalle, di Arrigo Castellani e di Domenico De Robertis, l\u2019attivit\ue0 dei quali ha esercitato un influsso durevole sulle attivit\ue0 dell\u2019OVI, rivelandosi determinante nell\u2019attuale configurazione del TLIO: il corpus e il vocabolario a loro volta oggi consentono alla filologia italiana un grado di approfondimento sulla tradizione testuale impensabile per le altre lingue medievali europee