Surprisingly Little O VI Emission Arises in the Local Bubble

This paper reports the first study of the O VI resonance line emission (1032, 1038 Angstroms) originating in the Local Bubble (or Local Hot Bubble) surrounding the solar neighborhood. In spite of the fact that O VI absorption within the Local Bubble has been observed, no resonance line emission was detected during our 230 ksec Far Ultraviolet Spectroscopic Explorer observation toward a ``shadowing'' filament in the southern Galactic hemisphere. As a result, tight 2 sigma upper limits are set on the intensities in the 1032 and 1038 Angstrom emission lines: 500 and 530 photons cm^{-2} s^{-1} sr^{-1}, respectively. These values place strict constraints on models and simulations. They suggest that the O VI-bearing plasma and the X-ray emissive plasma reside in distinct regions of the Local Bubble and are not mixed in a single plasma, whether in equilibrium with T ~ 10^6 K or highly overionized with T ~ 4 to 6 x 10^4 K. If the line of sight intersects multiple cool clouds within the Local Bubble, then the results also suggest that hot/cool transition zones differ from those in current simulations. With these intensity upper limits, we establish limits on the electron density, thermal pressure, pathlength, and cooling timescale of the O VI-bearing plasma in the Local Bubble. Furthermore, the intensity of O VI resonance line doublet photons originating in the Galactic thick disk and halo is determined (3500 to 4300 photons cm^{-2} s^{-1} sr^{-1}), and the electron density, thermal pressure, pathlength, and cooling timescale of its O VI-bearing plasma are calculated. The pressure in the Galactic halo's O VI-bearing plasma (3100 to 3800 K cm^{-3}) agrees with model predictions for the total pressure in the thick disk/lower halo. We also report the results of searches for other emission lines.Comment: accepted by ApJ, scheduled for May 2003, replacement astro-ph submission corrects typos and grammatical errors in original versio

Microstructure of the Local Interstellar Cloud and the Identification of the Hyades Cloud

We analyze high-resolution UV spectra of the Mg II h and k lines for 18 members of the Hyades Cluster to study inhomogeneity along these proximate lines of sight. The observations were taken by the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). Three distinct velocity components are observed. All 18 lines of sight show absorption by the Local Interstellar Cloud (LIC), ten stars show absorption by an additional cloud, which we name the Hyades Cloud, and one star exhibits a third absorption component. The LIC absorption is observed at a lower radial velocity than predicted by the LIC velocity vector derived by Lallement & Bertin (1992) and Lallement et al. (1995), (v(predicted LIC) - v(observed LIC) = 2.9 +/- 0.7 km/s), which may indicate a compression or deceleration at the leading edge of the LIC. We propose an extention of the Hyades Cloud boundary based on previous HST observations of other stars in the general vicinity of the Hyades, as well as ground-based Ca II observations. We present our fits of the interstellar parameters for each absorption component. The availability of 18 similar lines of sight provides an excellent opportunity to study the inhomogeneity of the warm, partially ionized local interstellar medium (LISM). We find that these structures are roughly homogeneous. The measured Mg II column densities do not vary by more than a factor of 2 for angular separations of < 8 degrees, which at the outer edge of the LIC correspond to physical separations of < 0.6 pc.Comment: 35 pages, 11 figures, AASTEX v.5.0 plus EPSF extensions in mkfig.sty; accepted by Ap

Thermal Pressures in Neutral Clouds inside the Local Bubble, as Determined from C I Fine-Structure Excitations

High-resolution spectra covering absorption features from interstellar C I were recorded for four early-type stars with spectrographs on HST, in a program to measure the fine-structure excitation of this atom within neutral clouds inside or near the edge of the Local Bubble, a volume of hot (T ~ 10^6 K) gas that emits soft x-rays and extends out to about 100 pc away from the Sun. The excited levels of C I are populated by collisions, and the ratio of excited atoms to those in the ground level give a measure of the local thermal pressure. Absorptions from the two lowest levels of C I were detected toward alpha Del and delta Cyg, while only marginal indications of excited C I were obtained for gamma Ori, and lambda Lup. Along with temperature limits derived by other means, the C I fine-structure populations indicate that for the clouds in front of gamma Ori, delta Cyg and alpha Del, 10^3 < p/k < 10^4 cm^{-3}K at about the +-1 sigma confidence level in each case. The results for lambda Lup are not as well constrained, but still consistent with the other three stars. The results indicate that the thermal pressures are below generally accepted estimates p/k > 10^4 cm^{-3}K for the Local Bubble, based on the strength of x-ray and EUV emission from the hot gas. This inequality of pressure for these neutral clouds and their surroundings duplicates a condition that exists for the local, partly-ionized cloud that surrounds the Sun. An appendix in the paper describes a direct method for determining and eliminating small spectral artifacts arising from variations of detector sensitivity with position.Comment: 33 pages, 7 figures, submitted to the Astrophysical Journa

Maximum Entropy Reconstruction of the Interstellar Medium: I. Theory

We have developed a technique to map the three-dimensional structure of the local interstellar medium using a maximum entropy reconstruction technique. A set of column densities N to stars of known distance can in principle be used to recover a three-dimensional density field n, since the two quantities are related by simple geometry through the equation N = C n, where C is a matrix characterizing the stellar spatial distribution. In practice, however, there is an infinte number of solutions to this equation. We use a maximum entropy reconstruction algorithm to find the density field containing the least information which is consistent with the observations. The solution obtained with this technique is, in some sense, the model containing the minimum structure. We apply the algorithm to several simulated data sets to demonstrate its feasibility and success at recovering ``real'' density contrasts. This technique can be applied to any set of column densities whose end points are specified. In a subsequent paper we shall describe the application of this method to a set of stellar color excesses to derive a map of the dust distribution, and to soft X-ray absorption columns to hot stars to derive a map of the total density of the interstellar medium.Comment: 23 pages, 7 fig.; accepted for publication in the Ap.

Efficient bone formation by gene transfer of human LIM mineralization protein-3

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Discovery of Reflection Nebulosity Around Five Vega-like Stars

Coronagraphic optical observations of six Vega-like stars reveal reflection nebulosities, five of which were previously unknown. The nebulosities illuminated by HD 4881, HD 23362, HD 23680, HD 26676, and HD 49662 resemble that of the Pleiades, indicating an interstellar origin for dust grains. The reflection nebulosity around HD 123160 has a double-arm morphology, but no disk-like feature is seen as close as 2.5 arcsec from the star in K-band adaptive optics data. We demonstrate that uniform density dust clouds surrounding HD 23362, HD 23680 and HD 123160 can account for the observed 12-100 micron spectral energy distributions. For HD 4881, HD 26676, and HD 49662 an additional emission source, such as from a circumstellar disk or non-equilibrium grain heating, is required to fit the 12-25 micron data. These results indicate that in some cases, particularly for Vega-like stars located beyond the Local Bubble (>100 pc), the dust responsible for excess thermal emission may originate from the interstellar medium rather than from a planetary debris system.Comment: The Astrophysical Journal, in press for March, 2002 (32 pages, 13 figures

Comprensión del imaginario colectivo para la protección del patrimonio arqueológico monumental del Sistema Serrano de Ventania (provincia de Buenos Aires, Argentina)

Durante los años 2010 y 2011, se continuaron con las diversas tareas vinculadas a la protección, difusión e investigación del patrimonio arqueológico monumental del Sistema Serrano de Ventania, en el marco de los proyectos de extensión universitaria acreditados en la Facultad de Ciencias Naturales y Museo de la Universidad Nacional de La Plata y en la Facultad de Humanidades y Artes de la Universidad Nacional de Rosario en colaboración con otras instituciones provinciales (Instituto Cultural de la Provincia de Buenos Aires) y municipales (Coronel Pringles, Saavedra y Tornquist). A partir del tipo de patrimonio arqueológico de la zona, que incluye estructuras líticas, piedras paradas, cuevas y aleros con arte rupestre, se consideró que su alta visibilidad deja a este registro más susceptible de sufrir deterioro por factores antrópicos, por lo cual se diseñaron distintas estrategias de difusión del conocimiento arqueológico, con el fin de prevenirlo. Entre las acciones más relevantes efectuadas, se pueden mencionar el registro del estado de conservación de los sitios arqueológicos con evidencias de monumentalidad, el relevamiento de opinión en las localidades de Tornquist, Saavedra y Pigüé, los encuentros participativos abiertos a todos los sectores de la población, el dictado de talleres interactivos para escolares entre 10 y 15 años y la realización de la I Feria de Ciencias Arqueológicas, entre otros. A través de las actividades realizadas se propuso la valoración del patrimonio arqueológico como recurso no renovable y la concientización de la comunidad para garantizar la protección del mismo.Many activities related to the protection, promotion and investigation of the monumental archaeological patrimony of the Sistema Serrano de Ventania were carried out during 2010 and 2011 as part of the universitary extension proyects accredited by the Universidad Nacional de La Plata and the Facultad de Humanidades y Artes de la Universidad Nacional de Rosario in collaboration with other provincial (Instituto Cultural de la Provincia de Buenos Aires) and municipal (Coronel Pringles, Saavedra and Tornquist) institutions. The high visibility of the archaeological patrimony of the area -which includdes standing stones, lithic structures, caves and rock shelters with rock art and stratigraphic siteswas considered to be one of the main reassons why it is highly affected by the anthropic factors of degradation. This fact was essential to design different strategies to promote the archaeological knowledge in order to prevent their deterioration. Among the most relevant activities, we can mention the assessment of the conservation condition of the monumental archaeological sites, opinion surveys in Tornquist, Saavedra and Pigüé conducted to different sectors of the communities, meetings open to all the community to discuss topics related to the conservation of the patrimony, workshops for students between 10 and 15 years old, and the I Feria de Ciencias Arqueológicas. Through these activities we proposed the valoration of the archaeological patrimony as a non-renewable resource and the concientization of the community to guarantee its protection.Facultad de Ciencias Naturales y Muse

Comprensión del imaginario colectivo para la protección del patrimonio arqueológico monumental del Sistema Serrano de Ventania (provincia de Buenos Aires, Argentina)

Durante los años 2010 y 2011, se continuaron con las diversas tareas vinculadas a la protección, difusión e investigación del patrimonio arqueológico monumental del Sistema Serrano de Ventania, en el marco de los proyectos de extensión universitaria acreditados en la Facultad de Ciencias Naturales y Museo de la Universidad Nacional de La Plata y en la Facultad de Humanidades y Artes de la Universidad Nacional de Rosario en colaboración con otras instituciones provinciales (Instituto Cultural de la Provincia de Buenos Aires) y municipales (Coronel Pringles, Saavedra y Tornquist). A partir del tipo de patrimonio arqueológico de la zona, que incluye estructuras líticas, piedras paradas, cuevas y aleros con arte rupestre, se consideró que su alta visibilidad deja a este registro más susceptible de sufrir deterioro por factores antrópicos, por lo cual se diseñaron distintas estrategias de difusión del conocimiento arqueológico, con el fin de prevenirlo. Entre las acciones más relevantes efectuadas, se pueden mencionar el registro del estado de conservación de los sitios arqueológicos con evidencias de monumentalidad, el relevamiento de opinión en las localidades de Tornquist, Saavedra y Pigüé, los encuentros participativos abiertos a todos los sectores de la población, el dictado de talleres interactivos para escolares entre 10 y 15 años y la realización de la I Feria de Ciencias Arqueológicas, entre otros. A través de las actividades realizadas se propuso la valoración del patrimonio arqueológico como recurso no renovable y la concientización de la comunidad para garantizar la protección del mismo.Many activities related to the protection, promotion and investigation of the monumental archaeological patrimony of the Sistema Serrano de Ventania were carried out during 2010 and 2011 as part of the universitary extension proyects accredited by the Universidad Nacional de La Plata and the Facultad de Humanidades y Artes de la Universidad Nacional de Rosario in collaboration with other provincial (Instituto Cultural de la Provincia de Buenos Aires) and municipal (Coronel Pringles, Saavedra and Tornquist) institutions. The high visibility of the archaeological patrimony of the area -which includdes standing stones, lithic structures, caves and rock shelters with rock art and stratigraphic siteswas considered to be one of the main reassons why it is highly affected by the anthropic factors of degradation. This fact was essential to design different strategies to promote the archaeological knowledge in order to prevent their deterioration. Among the most relevant activities, we can mention the assessment of the conservation condition of the monumental archaeological sites, opinion surveys in Tornquist, Saavedra and Pigüé conducted to different sectors of the communities, meetings open to all the community to discuss topics related to the conservation of the patrimony, workshops for students between 10 and 15 years old, and the I Feria de Ciencias Arqueológicas. Through these activities we proposed the valoration of the archaeological patrimony as a non-renewable resource and the concientization of the community to guarantee its protection.Facultad de Ciencias Naturales y Muse

In Vitro Antibacterial Activity of Essential Oils against Streptococcus pyogenes

Streptococcus pyogenes plays an important role in the pathogenesis of tonsillitis. The present study was conducted to evaluate the in vitro antibacterial activities of 18 essential oils chemotypes from aromatic medicinal plants against S. pyogenes. Antibacterial activity of essential oils was investigated using disc diffusion method. Minimum Inhibitory Concentration of essential oils showing an important antibacterial activity was measured using broth dilution method. Out of 18 essential oils tested, 14 showed antibacterial activity against S. pyogenes. Among them Cinnamomum verum, Cymbopogon citratus, Thymus vulgaris CT thymol, Origanum compactum, and Satureja montana essential oils exhibited significant antibacterial activity. The in vitro results reported here suggest that, for patients suffering from bacterial throat infections, if aromatherapy is used, these essential oils, considered as potential antimicrobial agents, should be preferred