Spectrophotometry of early type stars

A photoelectric spectrum scanner attached to the 16-inch telescope of the Cerro Tololo Inter-American Observatory was used to determine the relative spectral intensity distribution for early type stars. Observations on a minimun of three nights per star have been obtained for about two hundred stars. The tracings extend from 3100 Å to 6000 Å. They were obtained with a slit width from 50 Å to 80 Å , and thus can be used also for a determination of the equivalent widths of H-beta, H-gamma, and H-delta, As a byproduct precise information on the monochromatic atmospheric extinction at Cerro Tololo is obtained. In this investigation special, emphasis was given to Be stars.Asociación Argentina de Astronomí

Spectrophotometry of early type stars

A photoelectric spectrum scanner attached to the 16-inch telescope of the Cerro Tololo Inter-American Observatory was used to determine the relative spectral intensity distribution for early type stars. Observations on a minimun of three nights per star have been obtained for about two hundred stars. The tracings extend from 3100 Å to 6000 Å. They were obtained with a slit width from 50 Å to 80 Å , and thus can be used also for a determination of the equivalent widths of H-beta, H-gamma, and H-delta, As a byproduct precise information on the monochromatic atmospheric extinction at Cerro Tololo is obtained. In this investigation special, emphasis was given to Be stars.Asociación Argentina de Astronomí

Spectrophotometry of early type stars

A photoelectric spectrum scanner attached to the 16-inch telescope of the Cerro Tololo Inter-American Observatory was used to determine the relative spectral intensity distribution for early type stars. Observations on a minimun of three nights per star have been obtained for about two hundred stars. The tracings extend from 3100 Å to 6000 Å. They were obtained with a slit width from 50 Å to 80 Å , and thus can be used also for a determination of the equivalent widths of H-beta, H-gamma, and H-delta, As a byproduct precise information on the monochromatic atmospheric extinction at Cerro Tololo is obtained. In this investigation special, emphasis was given to Be stars.Asociación Argentina de Astronomí

Genomic analysis of eight native plasmids of the phytopathogen Pseudomonas syringae

Comunicación a conferenciaThe pPT23A family of plasmids (PFPs) appears to be indigenous to the plant pathogen Pseudomonas syringae and these plasmids are widely distributed and widely transferred among pathovars of P. syringae and related species. PFPs are sources of accessory genes for their hosts that can include genes important for virulence and epiphytic colonization of plant leaf surfaces. Further understanding of the evolution of the pPT23A plasmid family and the role of these plasmids in P. syringae biology and pathogenesis, requires the determination and analysis of additional complete, closed plasmid genome sequences. Therefore, our main objective was to obtain complete genome sequences from PFPs from three different P. syringae pathovars and perform a comparative genomic analysis. In this work plasmid DNA isolation, purification by CsCl-EtBr gradients, and sequencing using 454 platform, were used to obtain the complete sequence of P. syringae plasmids. Different bioinformatic tools were used to analyze the plasmid synteny, to identify virulence genes (i.e. type 3 effectors) and to unravel the evolutionary history of PFPs. Our sequence analysis revealed that PFPs from P. syringae encode suites of accessory genes that are selected at different levels (universal, interpathovar and intrapathovar). The conservation of type IVSS encoding conjugation functions also contributes to the distribution of these plasmids within P. syringae populations. Thus, this study contributes to unravel the genetic basis of the role of PFPs in different P. syringae lifestyles.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Isolation, characterization and selection of bacterial isolates from a suppressive soil with beneficial traits to plants

Backgrounds This study focused on the characterization and selection of bacterial strains obtained from a suppressive soil displaying antifungal activity against the soilborne phytopathogenic fungi Rosellinia necatrix. Bacterial profile from this suppressive soil were first obtained by 16S rRNA gene sequencing, revealing a significant increase in the bacterial class Gammaproteobacteria, especially in some antagonistic representatives of Pseudomonas spp. Objectives To obtain and characterize a collection of 246 bacterial isolates obtained from this suppressive soil, in order to identify new strains with antifungal activity against fungal phytopathogens. Methods To obtain the bacterial collection, we performed an isolation on a selective medium for Pseudomonas-like microorganisms. Further characterization tests were used in order to analyse the bacterial collection, including identification of the general metabolic profile of glucose, the profiling of antifungals produced, including both the putative production of antifungal compounds and lytic exoenzymes, and the evaluation of traits related with beneficial effects on plants. Conclusions A final selection of representative strains resulted in antifungal isolates belonging to the genus Pseudomonas, but also some representatives of the genera Serratia and Stenotrophomonas. These selected strains were tested for plant protection by an in vivo experiment using avocado and wheat plants challenged by the pathogen R. necatrix, showing all of them an antifungal ability and plant disease protection. Pseudomonas-like strains isolated from suppressive soils constitute an excellent source for novel microbial biocontrol agents against soilborne fungal pathogens. This work was supported by grant AGL2014-52518-C2-1-R. Carmen Vida and Sandra Tienda are supported by a PhD fellowship from the FPI program of the Spanish Government.This work was supported by grant AGL2014-52518-C2-1-R. Carmen Vida and Sandra Tienda are supported by a PhD fellowship from the FPI program of the Spanish Government; Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Suspected symbiotic stars

During 1987 we were engaged in a program of observation of planetary nebulae and symbiotic stars. The program included a group of five objects classified as suspected symbiotic stars: CD-3608436, Sa3-43, 1 Th4-4, V3804 Sgr and He2-104. All of then have been observed three times. They all appear in Allen's Catalogue of symbiotic stars as suspected symbiotic. They all share two characteristics which are typical of symbiotic objects: the Balmer decrement is very steep, and the relative intensity of the [0 III] lines, I(λ4363)/I(λ5007), is larger than could be expected for planetary nebulae. Four of them do not show the typical lines at λ6830 and λ7088. The spectra of these objects are presented and their characteristics are discussed; we also discuss their position in the diagnostic diagrams based on the intensities of the forbidden lines [0 III] λλ 4363 and 5007, presented by one of us (Gutiérrez-Moreno) at the Anniversary Symposium of Cerro Tololo. It is concluded that, according to these diagrams and the general spectral characteristics, all these objets are symbiotic stars; this fact is evident from the spectrum itself for CD-36°8436 and, to a lesser extent, for SA3-43, Th4-4 and V3894 Sgr. He2-104 presents a special case, since the characteristic of its continuum correspond exactly to those of a planetary nebula. Nevertheless, its position in the diagrams previously mentioned and the presence of some forbidden emission lines, typical of symbiotic stars, allow its classification in this last group.Asociación Argentina de Astronomí

Two planetary nebulae near the galactic center

Observations of two emission objects located in the direction of the galactic center have been made: They are: M3-44 = PK 359-1°2, M2-19 = PK 0-1°5. They are both objects of very low excitation, classified previously as PN?, and with few or no published observations of optical line intensities. Both are included in the IRAS Point Source Catalogue. The spectra were obtained at Cerro Tololo Inter-American Observatory, using the 1.5 m telescope equipped with a UV SIT Vidicon detector, and with additional spectra obtained for M3-44 using the 4 m telescope equipped with a CCD detector. From the analysis of these observations the following conclusions have been reached: a)M3-44 is a very low excitation object (excitation class 0, hydrogen Zanstra temperature of the nebula ≃ 8000K), with a mean square electron density ≃ 3000, and with S II condensation of very high density; and with S Ii condensation of very high density; and b) M2-19 has somewhat higher excitation (excitation class 2, hydrogen Zanstra temperature of the central star ≃ 26000-30000 K, electron temperature ≃ 8500-9000 K), and electron density of the order of 1000. From the IRAS Catalogue observations we may deduce that both objects are rich in dust, with two components of different black body temperature: a "hot" component with T ≃ 100K and a cold component with T ≃ 20K, being the mass of the hot component about 1/1000 of the cold component. From all these considerations, we believe that M2-19 has all the characteristics of a low excitation planetary nebula, while the characteristics of M3-44 would allow its classification as a compact H II region.Asociación Argentina de Astronomí

Consideraciones para el análisis de la marcha humana. Técnicas de videogrametría, electromiografía y dinamometría

El análisis de la marcha humana resulta ser de gran utilidad para una amplia gama de aplicaciones, como el diagnóstico y elección de tratamientos en pacientes con enfermedades neuro-músculo-esqueléticas. Los métodos y tecnologías existentes para este análisis son numerosos, y permiten la obtención de los parámetros cuantitativos característicos de un patrón de marcha de manera objetiva. Durante el análisis de marcha muchos factores deben ser considerados para realizar los estudios adecuadamente, algunos de ellos se deben tener en cuenta desde la etapa de configuración y planeación del laboratorio, otros para el proceso de adquisición de los parámetros, y otros para el análisis de los resultados. En este trabajo se presentan algunas de estas consideraciones que parten tanto de la revisión bibliográfica como de la experiencia directa con pacientes, enfocadas principalmente en sistemas que combinan técnicas de videogrametría, dinamometría y electromiografía, por ser estos los de mayor utilización en la actualidad.Human gait analysis has been used in a wide range of applications, such as diagnosis and treatment selection for patients with neuro-muscular-skeletal diseases. The methods and technologies that exist for gait analysis are numerous, and they allow the recollection of the main quantitative parameters of a gait pattern in an objective way. A lot of factors must be considered during gait analysis in order to obtain reliable results; some of them must be taken into account, including the planning and configuration of the laboratory, the acquisition process and the results analysis system. This paper presents some considerations derived from the literature review and also from the direct experience with patients. They are mainly focused in systems which use techniques such as videogrammetry, dynamometry and electromyography, since they are the most used nowadays

Electronic Origin of α″ to β Phase Transformation in Ti-Nb-Based Thin Films upon Hf Microalloying.

We present results on thin Ti-Nb-based films containing Hf at various concentrations grown by magnetron sputtering. The films exhibit α" patterns at Hf concentrations up to 11 at.%, while at 16 at.% Hf, the β-phase emerges as a stable structure. These findings were consolidated by ab initio calculations, according to which the α"-β transformation is manifested in the calculation of the electronic band energies for Hf contents between 11 and 18 at.%. It turns out that the β-phase transition originates from the Hf 5d contributions at the Fermi level and the Hf 6s hybridizations at low energies in the electronic density of states. Bonding-anti-bonding first neighbor features existing in the shifted plane destabilize the α″-phase, especially at high Hf concentrations, while the covalent-like features in the first neighborhood stabilize the corresponding plane of the β-phase. Thin films measurements and bulk total energy calculations agree that the lattice constants of both α″ and β phases increase upon Hf substitution. These results are important for the understanding of β-Ti-based alloys formation mechanisms and can be used for the design of suitable biocompatible materials