1,176 research outputs found
On the Origin of the -4.4 eV Band in CdTe(100)"
We calculate the bulk- (infinite system), (100)-bulk-projected- and
(100)-Surface-projected Green's functions using the Surface Green's Function
Matching method (SGFM) and an empirical tight-binding hamiltonian with
tight-binding parameters (TBP) that describe well the bulk band structure of
CdTe. In particular, we analyze the band (B--4) arising at --4.4 eV from the
top of the valence band at according to the results of Niles and
H\"ochst and at -4.6 eV according to Gawlik {\it et al.} both obtained by
Angle-resolved photoelectron spectroscopy (ARPES). We give the first
theoretical description of this band.Comment: 17 pages, Rev-TEX, CIEA-Phys. 02/9
New species of Entomobryini from Russia and Armenia (Collembola, Entomobryomorpha)
This paper is part of the results of a systematic study of the specimens of Entomobrya and related genera from various European museums and other material obtained from private collections. Various new species from Russia and Armenia were identified: Entomobrya karasukensis n. sp., Entomobrya tuvinica n. sp., Entomobrya pseudolanuginosa n. sp., Entomobrya stebaevae n. sp., Entomobrya kuznetsovae n. sp., Entomobrya brinevi n. sp., Entomobrya primorica n. sp., Entomobrya kabardinica n. sp., Entomobrya taigicola n. sp., Entomobryoides sotoadamesi n. sp. and Prodrepanura altaica n. sp. from Russia, and Entomobrya armeniensis n. sp. from Armenia. For the identification and description of these species we used the set of characters proposed by Jordana and Baquero (2005)
Sa Gleda cave (Majorca, Balearic Islands) and its fauna, with description of a new species of Oncopoduridae (Collembola)
A new species of Oncopodura (Collembola: Entomobryomorpha: Oncopoduridae) from a cave in Majorca is described. The new species can be distinguished from other species of the genus by the following characters: four distal leaf-shaped sensilla on antennal segment IV and another one on the basal part; PAO small, as a single vesicle; dens with distal outer hook-like spine; mucr with four teeth, with the basal one very sharp; basal part of dens with a large spine on the inner side; claw with a long lateral tooth. The discovery of this new species resulted from the speleological work that was carried out in the cave
A new type of arthropod photoreceptor
A new type of photoreceptor for the phylum Arthropoda, found in the class Collembola (Arthropoda, Hexapoda) is reported. This new light-sensitive structure consists of a pair of interocular vesicles present in the genus Vesicephalus Richards, 1964 and is anatomically related to the cluster of ommatidia. The absence of a lens, the presence of a rabdome in the upper part of the vesicle and the reflection and refraction of light by a hemolymph bubble with incidence to the rhabdomeric structure are the main traits of this new photoreceptor
A new genus and species of Entomobryidae (Collembola, Entomobryomorpha) from the Iberian peninsula
A new genus and species, Hispanobrya barrancoi Jordana and Baquero, gen. n., sp. n.
is described. It was found in the Gador Mountain range (Almer a, Spain). This genus is similar to
Capbrya Barra, 1999, from South Africa. The distinguishing characteristics of the new genus are the
presence of a post-antennal organ (PAO), no clear tenent hair, a characteristic unguis, the presence of
a reduced trochanteral organ, and flattened body setae. The distribution of the bothriotricha is similar
to that of the genus Capbrya
Performance of the modified Becke-Johnson potential
Very recently, in the 2011 version of the Wien2K code, the long standing
shortcome of the codes based on Density Functional Theory, namely, its
impossibility to account for the experimental band gap value of semiconductors,
was overcome. The novelty is the introduction of a new exchange and correlation
potential, the modified Becke-Johnson potential (mBJLDA). In this paper, we
report our detailed analysis of this recent work. We calculated using this
code, the band structure of forty one semiconductors and found an important
improvement in the overall agreement with experiment as Tran and Blaha [{\em
Phys. Rev. Lett.} 102, 226401 (2009)] did before for a more reduced set of
semiconductors. We find, nevertheless, within this enhanced set, that the
deviation from the experimental gap value can reach even much more than 20%, in
some cases. Furthermore, since there is no exchange and correlation energy term
from which the mBJLDA potential can be deduced, a direct optimization procedure
to get the lattice parameter in a consistent way is not possible as in the
usual theory. These authors suggest that a LDA or a GGA optimization procedure
is used previous to a band structure calculation and the resulting lattice
parameter introduced into the 2011 code. This choice is important since small
percentage differences in the lattice parameter can give rise to quite higher
percentage deviations from experiment in the predicted band gap value.Comment: 10 pages, 2 figures, 5 Table
Co-diversification of Enterococcus faecium Core Genomes and PBP5: Evidences of pbp5 Horizontal Transfer
Ampicillin resistance has greatly contributed to the recent dramatic increase of a cluster of human adapted Enterococcus faecium lineages (ST17, ST18, and ST78) in hospital-based infections. Changes in the chromosomal pbp5 gene have been associated with different levels of ampicillin susceptibility, leading to protein variants (designated as PBP5 C-types to keep the nomenclature used in previous works) with diverse degrees of reduction in penicillin affinity. Our goal was to use a comparative genomics approach to evaluate the relationship between the diversity of PBP5 among E. faecium isolates of different phylogenomic groups as well as to assess the pbp5 transferability among isolates of disparate clonal lineages. The analyses of 78 selected E. faecium strains as well as published E. faecium genomes, suggested that the diversity of pbp5 mirrors the phylogenomic diversification of E. faecium. The presence of identical PBP5 C-types as well as similar pbp5 genetic environments in different E. faecium lineages and clones from quite different geographical and environmental origin was also documented and would indicate their horizontal gene transfer among E. faecium populations. This was supported by experimental assays showing transfer of large (≈180–280 kb) chromosomal genetic platforms containing pbp5 alleles, ponA (transglycosilase) and other metabolic and adaptive features, from E. faecium donor isolates to suitable E. faecium recipient strains. Mutation profile analysis of PBP5 from available genomes and strains from this study suggests that the spread of PBP5 C-types might have occurred even in the absence of a significant ampicillin resistance phenotype. In summary, genetic platforms containing pbp5 sequences were stably maintained in particular E. faecium lineages, but were also able to be transferred among E. faecium clones of different origins, emphasizing the growing risk of further spread of ampicillin resistance in this nosocomial pathogen.This work was supported by Fundação para a Ciência e a Tecnologia (FCT)/Ministério da Educacão e Ciência (MEC) through national funds and co-financed by Fundo Europeu de Desenvolvimento Regional (FEDER) under the Partnership Agreement PT2020 with the reference UID/ MULTI/04378/2013–POCI/01/0145/FERDER/007728 to CN and LP, Instituto de Salud Carlos III (Plan Estatal de I+D+i 2013-2016), Grant PI12-01581 and PI15-01307 to TMC and CIBERESP (CB06/02/0053) to FB, European Commission, Seventh Framework Program (EVOTARFP7-HEALTH-282004) to TMC and FB and the Regional Government of Madrid in Spain (PROMPT- S2010/BMD2414) to FB and TMC.Peer reviewedPeer Reviewe
Myosporidium merluccius n. g., n. sp. Infecting Muscle of Commercial Hake (Merluccius sp.) from Fisheries near Namibia
A new species of Microsporidia classified to a new genus was observed in the trunk muscle of commercial hake
(Merluccius capensis/paradoxus complex) from Namibian fisheries. Macroscopic examination revealed thin and dark filaments inserted
among muscle fibers. Inside the filaments were many sporophorous vesicles with about 30–50 spores per vesicle. The shape of the spore
was pyriform and the extruded polar filament was of moderate length (up to 4.29 mm, n512). This new species of Microsporidia is
described using macrophotography, microphotography, staining, and transmission electron microscopy (TEM), as well as molecular
methods. Its 16S rRNA was found to be similar to that of Microsporidium prosopium Kent et al., 1999, while both sequences were quite
different from 16S rRNA sequences known for other Microsporidia. Nevertheless, this new species is separated morphologically from
M. prosopium by the presence of 11–12 anisofilar coils and the formation of the xenoma at the site of infection. Type specie
The wideband backend at the MDSCC in Robledo. A new facility for radio astronomy at Q- and K- bands
The antennas of NASA's Madrid Deep Space Communications Complex (MDSCC) in
Robledo de Chavela are available as single-dish radio astronomical facilities
during a significant percentage of their operational time. Current
instrumentation includes two antennas of 70 and 34 m in diameter, equipped with
dual-polarization receivers in K (18 - 26 GHz) and Q (38 - 50 GHz) bands,
respectively. We have developed and built a new wideband backend for the
Robledo antennas, with the objectives (1) to optimize the available time and
enhance the efficiency of radio astronomy in MDSCC; and (2) to tackle new
scientific cases impossible to that were investigated with the old, narrow-band
autocorrelator. The backend consists of an IF processor, a FFT spectrometer
(FFTS), and the software that interfaces and manages the events among the
observing program, antenna control, the IF processor, the FFTS operation, and
data recording. The whole system was end-to-end assembled in August 2011, at
the start of commissioning activities, and the results are reported in this
paper. Frequency tunings and line intensities are stable over hours, even when
using different synthesizers and IF channels; no aliasing effects have been
measured, and the rejection of the image sideband was characterized. The first
setup provides 1.5 GHz of instantaneous bandwidth in a single polarization,
using 8192 channels and a frequency resolution of 212 kHz; upgrades under way
include a second FFTS card, and two high-resolution cores providing 100 MHz and
500 MHz of bandwidth, and 16384 channels. These upgrades will permit
simultaneous observations of the two polarizations with instantaneous
bandwidths from 100 MHz to 3 GHz, and spectral resolutions from 7 to 212 kHz.Comment: 9 pages, 8 figures. Accepted to Astronomy and Astrophysic
Mariposas diurnas de Pamplona
Esta obra se encarga de analizar las características principales de las mariposas
existentes en Pamplona, clasificándolas por familias, tipología y variedad, así
como explicando las cuatro fases que atraviesan durante su ciclo vital: huevo,
oruga, pupa y adulto
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