1,318 research outputs found

    Extreme secondary sexual dimorphism in the genus Florarctus (Heterotardigrada: Halechiniscidae)

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    Secondary sexual dimorphism in florarctin tardigrades is a well-known phenomenon. Males are usually smaller than females, and primary clavae are relatively longer in the former. A new species Florarctus bellahelenae, collected from subtidal coralline sand just behind the reef fringe of Long Island, Chesterfield Reefs (Pacific Ocean), exhibits extreme secondary dimorphism. Males have developed primary clavae that are much thicker and three times longer than those present in females. Furthermore, the male primary clavae have an accordion-like outer structure, whereas primary clavae are smooth in females. Other species of Florarctus Delamare-Deboutteville & Renaud-Mornant, 1965 inhabiting the Pacific Ocean were investigated. Males are typically smaller than females, but males of Florarctus heimi Delamare-Deboutteville & Renaud-Mornant, 1965 and females of Florarctus cervinus Renaud-Mornant, 1987 have never been recorded. The Renaud-Mornant collection was re-examined, and type series were analysed. Florarctus heimi and F. cervinus were always found together in the coralline sand of Heron Island (Great Barrier Reef). The animals were kept alive and surveyed in the laboratory of the Queensland Museum. All studied individuals of the larger F. heimi (up to ca. 400 μm) were females, and all adults of the smaller F. cervinus (about 170 μm) were males. Males of F. cervinus were observed mating with females of F. heimi. Following those morphological and behavioural lines of evidence, we propose that F. cervinus is a junior synonym of F. heimi. Based on the discovery of dimorphism in F. bellahelenae sp. nov. and the strong sex-related morphological disparities in F. heimi, we suggest that extreme secondary dimorphism may be present in other florarctin arthrotardigrades

    Intrinsic approximation for fractals defined by rational iterated function systems - Mahler's research suggestion

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    Following K. Mahler's suggestion for further research on intrinsic approximation on the Cantor ternary set, we obtain a Dirichlet type theorem for the limit sets of rational iterated function systems. We further investigate the behavior of these approximation functions under random translations. We connect the information regarding the distribution of rationals on the limit set encoded in the system to the distribution of rationals in reduced form by proving a Khinchin type theorem. Finally, using a result of S. Ramanujan, we prove a theorem motivating a conjecture regarding the distribution of rationals in reduced form on the Cantor ternary set

    Relative abundance and geographical variation of Culex pipiens and Culex torrentium (Diptera: Culicidae) in CO2-baited traps in Denmark

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    Abstract: European Culex pipiens and Culex torrentium are morphological fairly similar mosquito species with potentially different vector competences for pathogenic viruses. The relative abundance of the two species is therefore important for quantifying the potential for disease transmission in Denmark. Mosquitoes were sampled from 74 different sites in Denmark with CO2 and octenol-baited suction traps. A total of 285 Culex specimens were identified to species using a restriction enzyme assay. Culex pipiens was the dominating species with 220 (77%) specimens caught at 22 different sites, while 65 (23%) specimens were identified as C. torrentium and only caught at 4 sites. The ratio of the two species differed significantly between sites with C. torrentium dominating in just a single location. Both mosquito species were predominantly caught late in the Danish mosquito season, from mid-August and onwards

    Kan simple ændringer i underviserens undervisning og fremtoning ændre de studerendes engagement?

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    The water abundance behind interstellar shocks: results from HerschelHerschel/PACS and SpitzerSpitzer/IRS observations of H2_2O, CO, and H2_2

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    We have investigated the water abundance in shock-heated molecular gas, making use of HerschelHerschel measurements of far-infrared CO and H2_2O line emissions in combination with SpitzerSpitzer measurements of mid-IR H2_2 rotational emissions. We present far-infrared line spectra obtained with HerschelHerschel's PACS instrument in range spectroscopy mode towards two positions in the protostellar outflow NGC 2071 and one position each in the supernova remnants W28 and 3C391. These spectra provide unequivocal detections, at one or more positions, of 12 rotational lines of water, 14 rotational lines of CO, 8 rotational lines of OH (4 lambda doublets), and 7 fine-structure transitions of atoms or atomic ions. We first used a simultaneous fit to the CO line fluxes, along with H2_2 rotational line fluxes measured previously by SpitzerSpitzer, to constrain the temperature and density distribution within the emitting gas; and we then investigated the water abundances implied by the observed H2_2O line fluxes. The water line fluxes are in acceptable agreement with standard theoretical models for nondissociative shocks that predict the complete vaporization of grain mantles in shocks of velocity v25v \sim 25 km/s, behind which the characteristic gas temperature is 1300\sim 1300 K and the H2_2O/CO ratio is 1.2Comment: 42 pages, 15 figures, accepted for publication in the Astrophysical Journa

    Efficient intra- and inter-night linking of asteroid detections using kd-trees

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    The Panoramic Survey Telescope And Rapid Response System (Pan-STARRS) under development at the University of Hawaii's Institute for Astronomy is creating the first fully automated end-to-end Moving Object Processing System (MOPS) in the world. It will be capable of identifying detections of moving objects in our solar system and linking those detections within and between nights, attributing those detections to known objects, calculating initial and differentially-corrected orbits for linked detections, precovering detections when they exist, and orbit identification. Here we describe new kd-tree and variable-tree algorithms that allow fast, efficient, scalable linking of intra and inter-night detections. Using a pseudo-realistic simulation of the Pan-STARRS survey strategy incorporating weather, astrometric accuracy and false detections we have achieved nearly 100% efficiency and accuracy for intra-night linking and nearly 100% efficiency for inter-night linking within a lunation. At realistic sky-plane densities for both real and false detections the intra-night linking of detections into `tracks' currently has an accuracy of 0.3%. Successful tests of the MOPS on real source detections from the Spacewatch asteroid survey indicate that the MOPS is capable of identifying asteroids in real data.Comment: Accepted to Icaru
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