5,277 research outputs found
The American species of the annulatipes group of the subgenus Lepidohelea, genus Forcipomyia (Diptera: Ceratopogonidae)
The annulatipes group of the genus Forcipomyia Meigen, subgenus Lepidohelea Kieffer, is represented in the Western Hemisphere by 12 species. Keys are presented for their identification, and to distinguish them from other groups of the subgenus Lepidohelea. The three previously known species, annulatipes Macfie, brasiliensis Macfie, and kuanoskeles Macfie, from southern Brazil, as well as the following nine new species, are described and illustrated: bahiensis, basifemoralis, bifida, convexipenis, euthystyla, gravesi, herediae, hobbsi, and weemsi
A revision of the Neotropical predaceous midges of Brachypogon (Brachypogon) Kieffer (Diptera: Ceratopogonidae)
This revision of the Neotropical predaceous midges of the genus Brachypogon (Brachypogon) Kieffer, recognizes 18 extant species, including the following 12 new species: Brachypogon (B.) apunctipennis, bifidus, bimaculatus, ecuadorensis, ethelae, insularis, monicae, pseudoparaensis, schmitzi, spatuliformis, telesfordi, and woodruffi. Two species groups are recognized, the fuscivenosus and impar groups. The hitherto unknown male of B. paraensis Wirth & Blanton is described and illustrated, and the female of that species as well as both sexes of B. impar (Johannsen) and B. fuscivenosus (Lutz) are redescribed and illustrated. Diagnoses are provided for previously described species, as well as a key for the recognition of all Neotropical species. New records of B. impar are from Brazil, Colombia, and Argentina
Optical emission investigation of laser-produced MgB2 plume expanding in an Ar buffer gas
Optical emission spectroscopy is used to study the dynamics of the plasma
generated by pulsed-laser irradiation of a MgB2 target, both in vacuum and at
different Ar buffer gas pressures. The analysis of the time-resolved emission
of selected species shows that the Ar background gas strongly influences the
plasma dynamics. Above a fixed pressure, plasma propagation into Ar leads to
the formation of blast waves causing both a considerable increase of the
fraction of excited Mg atoms and a simultaneous reduction of their kinetic flux
energy. These results can be particularly useful for optimizing MgB2 thin film
deposition processes.Comment: 11 pages,4 figures, Applied Physics Letters in pres
The biting and predaceous midges of Guadeloupe (Diptera: Ceratopogonidae). I. Species of the subfamily Ceratopogoninae
We provide new records of biting and predaceous midges (Diptera: Ceratopogonidae) from Guadeloupe in the subfamily Ceratopogoninae, including descriptions and illustrations of three new predaceous species in the genera, Parabezzia Malloch, Stilobezzia Kieffer and Palpomyia Meigen, respectively, and the first records of the New World predaceous genus, Amerohelea Grogan and Wirth, from the Caribbean region. We also provide the first Guadeloupe records of the biting midges, Culicoides (Anilomyia) decor (Williston), C. (Avaritia) pusillus Lutz, C. (Drymodesmyia) bredini Wirth and Blanton, C. (D.) poikilonotus Macfie, C. (Haematomyidium) hoffmani Fox, C. (Hoffmania) insignis Lutz, C. rangeli Ortiz and Mirsa and C. trilineatus Fox, and the predaceous midges, Brachypogon (Brachypogon) bifidus Spinelli and Grogan, B. (B.) telesfordi Spinelli and Grogan, B. (B.) woodruffi Spinelli and Grogan, Monohelea maya Felippe-Bauer, Huerta and Ibåñez-Bernal, Stilobezzia (Stilobezzia) diminuta Lane and Forattini, S. (S.) thomsenae Wirth, Amerohelea galindoi Grogan and Wirth, Bezzia (Bezzia) flinti Spinelli and Wirth, B. (Homobezzia) venustula (Williston) and Palpomyia insularis Spinelli and Grogan
The quality of web communication by Italian tourist ports
Nautical tourism is a growing form of tourism, and the Mediterranean Sea is a major destination. Italy has a long tradition in nautical tourism, as its large number of tourism ports refl ects. Ports are core actors in nautical tourism systems, devoted to meeting increasing and complex demand by nautical tourists; marketing communication is consequently a critical activity, for tourist ports, where websites play a crucial role. However, despite its importance, the evaluation of tourist ports websites is an almost unexplored research fi eld, where a large research gap exists. Our paper evaluates the quality of 51 Italian tourist ports websites using the 2QCV3Q model, a multi-purpose qualitative evaluation tool. Th e overall quality of Italian tourist ports websites was assessed on the basis of comparison to a group of benchmark ports in the Mediterranean Sea and worldwide. Results suggest that Italian tourist ports websites require improvement, especially of their content and the services provided. In this respect, our methodology provides an exhaustive assessment of the quality of a port's website and its determinants, helping to support managers in identifying the strengths and weaknesses of their
website and prioritizing related actions
Exploring the phase diagram of the two-impurity Kondo problem
A system of two exchange-coupled Kondo impurities in a magnetic field gives
rise to a rich phase space hosting a multitude of correlated phenomena.
Magnetic atoms on surfaces probed through scanning tunnelling microscopy
provide an excellent platform to investigate coupled impurities, but typical
high Kondo temperatures prevent field-dependent studies from being performed,
rendering large parts of the phase space inaccessible. We present an integral
study of pairs of Co atoms on insulating Cu2N/Cu(100), which each have a Kondo
temperature of only 2.6 K. In order to cover the different regions of the phase
space, the pairs are designed to have interaction strengths similar to the
Kondo temperature. By applying a sufficiently strong magnetic field, we are
able to access a new phase in which the two coupled impurities are
simultaneously screened. Comparison of differential conductance spectra taken
on the atoms to simulated curves, calculated using a third order transport
model, allows us to independently determine the degree of Kondo screening in
each phase.Comment: paper: 14 pages, 4 figures; supplementary: 3 pages, 1 figure, 1 tabl
On the nature of the near-UV extended light in Seyfert galaxies
We study the nature of the extended near-UV emission in the inner kiloparsec
of a sample of 15 Seyfert galaxies which have both near-UV (F330W) and narrow
band [OIII] high resolution Hubble images. For the majority of the objects we
find a very similar morphology in both bands. From the [OIII] images we
construct synthetic images of the nebular continuum plus the emission line
contribution expected through the F330W filter, which can be subtracted from
the F330W images. We find that the emission of the ionised gas dominates the
near-UV extended emission in half of the objects. A further broad band
photometric study, in the bands F330W (U), F547M (V) and F160W (H), shows that
the remaining emission is dominated by the underlying galactic bulge
contribution. We also find a blue component whose nature is not clear in 4 out
of 15 objects. This component may be attributed to scattered light from the
AGN, to a young stellar population in unresolved star clusters, or to
early-disrupted clusters. Star forming regions and/or bright off-nuclear star
clusters are observed in 4/15 galaxies of the sample.Comment: 23 pages, 6 figures, 3 tables; accepted for publication in MNRA
Finding the âSweet-Spotâ of Mechanised Felling Machines
Understanding how stand and terrain parameters impact the productivity of harvesting machines is important for determining their optimum use. Productivity studies in forest operations are often carried out on new equipment, or on equipment being used in new conditions. Such information is normally presented as a productivity or efficiency function; that is, a regression equation that best represents the data. Most studies establish that piece size is the dominant predictor that impacts overall productivity. A common concept, know as the âpiece-size lawâ, is that productivity increases at a decreasing rate with increasing piece size. What is not well understood is the upper limit to this piece-size law. That is, as the trees get âtooâ large, the machine starts to struggle and we can expect a decrease in productivity. Four different mechanised felling machines were studied in New Zealand radiata pine plantations. Using more complex non-linear equations it was possible to identify an âoptimumâ piece-size for maximum productivity, whereby this âsweet-spotâ piece size for all machines is considerably smaller than their maximum. Unexpectedly, productivity tended to decrease gradually, not drop off suddenly beyond the optimum. Using more complex statistical functions when correlating piece size to productivity will help identifying the âsweet-spotâ
The Neotropical Predaceous Midges of the genus \u3ci\u3eBezzia\u3c/i\u3e (Diptera: Ceratopogonidae) Part IV. The \u3ci\u3edentifemur\u3c/i\u3e and \u3ci\u3evenustula\u3c/i\u3e Groups
The dentifemur and venustula groups of the subgenus Homobezzia Macfie, genus Bezzia Kieffer, are represented in the Neotropical Region by 12 species. A key is presented for their identification, and to distinguish them from other groups of the subgenus Homobezzia. The two previously known species, B. venustula (Williston) and B. snowi Lane, are described and illustrated, as well as the following ten new species: aitkeni, bromeliae, cayoensis, dentifemur, filiductus, fusca, mexicana, nigritibialis, pseudovenustula, and raposoensis. Bezzia concoloripes Made is regarded as a junior synonym of B. venustula (Williston)
Controlled complete suppression of single-atom inelastic spin and orbital cotunnelling
The inelastic portion of the tunnel current through an individual magnetic
atom grants unique access to read out and change the atom's spin state, but it
also provides a path for spontaneous relaxation and decoherence. Controlled
closure of the inelastic channel would allow for the latter to be switched off
at will, paving the way to coherent spin manipulation in single atoms. Here we
demonstrate complete closure of the inelastic channels for both spin and
orbital transitions due to a controlled geometric modification of the atom's
environment, using scanning tunnelling microscopy (STM). The observed
suppression of the excitation signal, which occurs for Co atoms assembled into
chain on a CuN substrate, indicates a structural transition affecting the
d orbital, effectively cutting off the STM tip from the spin-flip
cotunnelling path.Comment: 4 figures plus 4 supplementary figure
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