157 research outputs found
Primer registro de la familia Cydnidae (Hemiptera: Heteroptera) en Isla de Pascua, Chile
A new record from insular Chile for the Neotropical and Andean cydnid Melanaethus spinolae (Signoret, 1864) is presented. Specifically, the new record comes from Easter Island, making M. spinolae the first burrower bug found in this Oceanic island. The possible causes of the range expansion of this taxon are commented.Se presenta un nuevo registro del cídnido andino y neotropical Melanaethus spinolae (Signoret, 1863) para Chile insular. El nuevo registro proviene específicamente de Isla de Pascua, convirtiendo a esta chinche en el primer cídnido para esta isla oceánica. Se comentan las posibles causas de la expansión de este taxón
Pruning cuts affect wood necrosis but not the percentage of budburst or shoot development on spur pruned vines for different grapevine varieties
Two experimental studies were performed in this trial. In the first, the aim was to quantify wood necrosis generated by pruning cuts on aboveground permanent (arms and trunks) and non-permanent (spurs) woody structures of 'Cabernet Sauvignon' vines. In the second, the goal was to evaluate the effect of cutting distance from the basal end of the shoot in spur pruned vines on budburst and further shoot development for 'Grenache', 'Cabernet Franc' and 'Malbec' varieties. Based upon the first experiment, the area and depth of wood necrosis was highly influenced by the distance where the pruning cut was performed over the node. Furthermore, the diameter of the spur that was cut was not significantly related to either the area or the depth of the necrotic wood generated after the cut. Aboveground vine wood necrotic area ranged from 9 to 44 % of the total wood area measured in 'Cabernet Sauvignon' cordon trained spur pruned 25-year-old grapevines. For each vine a larger proportion of the necrotic wood (20 to 46 % of necrotic area) was present in the arms when compared to the trunks (1 to 28 % of necrotic area). As a result of the second experiment, spur budburst and further shoot development was not affected by the distance from the node where the pruning cut was performed for any of the cultivars considered in the study contrary to what is commonly believed
Contribución al conocimiento de Tegenaria domestica (Clerck, 1757) (Araneae: Agelenidae) en la Patagonia Austral
Se revisa y analiza la presencia de la araña Tegenaria domestica en la Patagonia austral. Se entregan nuevos registros para las provincias de Santa Cruz y Tierra del Fuego en Argentina y se confirma su presencia en la región de Magallanes en Chile. Se discute la significancia de los registros históricos y los nuevos aquí entregados. Se proveen ilustraciones para identificar correctamente esta especie.The presence of the spider Tegenaria domestica in southern Patagonia is revised and analyzed. New records are provided from Santa Cruz and Tierra del Fuego Province Argentina, and its presence is confirmed in Magallanes Region, Chile. The significance of the historical records and the new ones is discussed. Illustrations are provided to correctly identify the species.Fil: Faúndez, Eduardo I.. Universidad de Magallanes; ChileFil: Carvajal, Mariom A.. Universidad de Magallanes; ChileFil: Asplanato, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Raffo, Flavia. Parque Nacional Los Glaciares; ArgentinaFil: Vargas, Catalina J.. Universidad de Magallanes; Chil
A New Kind of Quinonic-Antibiotic Useful Against Multidrug-Resistant S. aureus and E. faecium Infections
Indexación: Scopus.A rapid emergence of resistant bacteria is occurring worldwide, endangering the efficacy of antibiotics and reducing the therapeutic arsenal available for treatment of infectious diseases. In the present study, we developed a new class of compounds with antibacterial activity obtained by a simple, two step synthesis and screened the products for in vitro antibacterial activity against ATCC® strains using the broth microdilution method. The compounds exhibited minimum inhibitory concentrations (MIC) of 1⁻32 μg/mL against Gram-positive ATCC® strains. The structure⁻activity relationship indicated that the thiophenol ring is essential for antibacterial activity and the substituents on the thiophenol ring module, for antibacterial activity. The most promising compounds detected by screening were tested against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREF) clinical isolates. We found remarkable activity against VREF for compounds 7 and 16, were the MIC50/90 were 2/4 µg/mL and 4/4 µg/mL, respectively, while for vancomycin the MIC50/90 was 256/512 µg/mL. Neither compound affected cell viability in any of the mammalian cell lines at any of the concentrations tested. These in vitro data show that compounds 7 and 16 have an interesting potential to be developed as new antibacterial drugs against infections caused by VREF.https://www.mdpi.com/1420-3049/23/7/177
Magnetic transitions induced by pressure and magnetic field in a two-orbital -electron model in cubic and tetragonal lattices
We investigate the onset and evolution of under the simultaneous application
of pressure and magnetic field of distinct itinerant N\'eel states using the
underscreened Anderson Lattice Model (UALM) which has been proposed to describe
-electron systems. The model is composed by two narrow -bands (of either
or character) that hybridize with a wide -band and local
-electron interactions. We consider both cubic and tetragonal lattices. The
N\'eel order parameters and are assumed to be
fixed by an Ising anisotropy. The applied magnetic field is parallel to
the anisotropy axis. It has been assumed that the variation of the band width
is sensitive to pressure. In the absence of a magnetic field, the increase
of takes the system from the phase AF to another phase AF. The
phase AF occurs when while in the AF
phase the gaps satisfy . In the presence of a
magnetic field , the phase AF is quickly suppressed and reappears
again at intermediate values of the magnetic field while it is predominant at
higher magnetic fields. The analysis of the partial density of states close to
the phase transition between the phases AF and AF, allows a better
understanding the mechanism responsible whereby the transition is induced by an
increase in the magnetic field. As a important general result, we found that
the magnetic field favours the phase AF while the phase AF is
suppressed. For the tetragonal lattice, the phase AF is even more favored
when and increases concomitantly, where and are the lattice
parameters
First record of promops davisoni (Thomas, 1921) (chiroptera, molossidae) from Chile and a description of its echolocation calls
[Primer registro de promops davisoni (Thomas, 1921) (chiroptera, molossidae) en Chile, y des-cripción de sus llamadas de ecolocación]Few studies have been conducted on the bat fauna of the Arica and Parinacota region, northern Chile. The genus Promops (Gervais, 1855) is a poorly known group of molossid bats, with three species widely distributed in Central and South America. We report for the first time the species Promops davisoni in Chile. Identification was based on echolocation calls obtained at the Azapa and Lluta valleys and compared to reference calls from Tacna, Peru. We report the species as far as 127 km south of the previous published southernmost record in Pampa Alta, Peru. In addition we obtained an individual found at the Anzota caves, near the city of Arica. The species is found on the coast and in the fluvial valleys of Northern Chile, with altitudes ranging from sea level to 822 m a.s.l. We propose that the distribution of P. davisoni may extend further south, to the locality of Tana in the Tarapacá region, based on the capacity of the species to cross distances of over 100 km over large desert areas. With this species, we increase the known bat fauna of Chile to 14 species, and the bat fauna of the Arica and Parinacota region to nine species. © SAREM, 2018.Peer reviewe
Spitzer-IRAC GLIMPSE of high mass protostellar objects. I Infrared point sources and nebulae
The GLIMPSE archive was used to obtain 3.6--8.0micron, point source
photometry and images for 381 massive protostellar candidates lying in the
Galactic mid-plane. The colours, magnitudes and spectral indicies of sources in
each of the 381 target fields were analysed and compared with the predictions
of 2D radiative transfer model simulations. Although no discernable embedded
clusters were found in any targets, multiple sources or associations of
redenned young stellar objects were found in many sources indicating
multiplicity at birth. The spectral index () of these point sources in
3.6--8.0mum bands display large values of =2--5. A color-magnitude
analog plot was used to identify 79 infrared counterparts to the HMPOs. Compact
nebulae are found in 75% of the detected sources with morphologies that can be
well described by core-halo, cometary, shell-like and bipolar geometries
similar to those observed in ultra-compact HII regions. The IRAC band SEDs of
the IR counterparts of HMPOs are best described to represent YSOs with a mass
range of 8--20\msun in their Class I stages when compared with 2D radiative
transfer models. They also suggest that the high values represent
reprocessed star/star+disk emission that is arising in the dense envelopes.
Thus we are witnessing the luminous envelopes around the protostars rather than
their photospheres or disks. We argue that the compact infrared nebulae likely
reflect the underlying physical structure of the dense cores and are found to
imitate the morphologies of known UCHII regions. Our results favour models of
continuuing accretion involving both molecular and ionised accretion components
to build the most massive stars rather than purely molecular rapid accretion
flows.Comment: 13 pages, 7 figures, accepted by A&
Thermo‑magnetic signature of a superconducting multi‑band square with rough surface
In the present work, we will study the efect that the surface roughness of the sample has on the magnetic and thermodynamic properties in a mesoscopic superconducting meso-square under an external magnetic feld in a zero-feld cooling process. We will analyze the magnetization, superconducting electronic density, free Gibbs energy, specifc heat and entropy as a function of the roughness of the sample in a superconducting two-band square taking a Josephson type inter-band coupling. We show that the magnetic and thermodynamic properties depend on the roughness percentage of its surface. Our investigation was carried out by numerically solving the two-band time-dependent Ginzburg–Landau equations
UGC 7388: a galaxy with two tidal loops
We present the results of spectroscopic and morphological studies of the
galaxy UGC7388 with the 8.1-m Gemini North telescope. Judging by its observed
characteristics, UGC7388 is a giant late-type spiral galaxy seen almost
edge-on. The main body of the galaxy is surrounded by two faint (\mu(B) ~ 24
and \mu(B) ~ 25.5) extended (~20-30 kpc) loop-like structures. A large-scale
rotation of the brighter loop about the main galaxy has been detected. We
discuss the assumption that the tidal disruption of a relatively massive
companion is observed in the case of UGC7388. A detailed study and modeling of
the observed structure of this unique galaxy can give important information
about the influence of the absorption of massive companions on the galactic
disks and about the structure of the dark halo around UGC7388.Comment: 8 pages, 5 figure
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