Geotechnical Units and the Damages Caused by Earthquakes in Valparaiso - Chile

The geotechnical units forming the foundation soil of Valparaiso city and constituting seven zones that exhibit different stratigraphic sequences are characterized. In addition, the evolution of the artificial backfilling’s located in the seaport is reported. The damages causes by Chile Earthquake of March 3, 1985 allow to establish for each zone the MSK intensities, which are varying between 7 1/2 and 8 1/2 in the flat-ground sector of Valparaiso, and between 7 1/4 and 7 1/2 in the hills. The major intensity in the flat sector is observed in areas whose artificial backfilling’s are exhibiting greater thickness and less consistency or less compacity

Different evolutionary stages in massive star formation. Centimeter continuum and H2O maser emission with ATCA

We present ATCA observations of the H2O maser line and radio continuum at 18.0GHz and 22.8GHz, toward a sample of 192 massive star forming regions containing several clumps already imaged at 1.2mm. The main aim of this study is to investigate the water maser and centimeter continuum emission (likely tracing thermal free-free emission) in sources at different evolutionary stages, using the evolutionary classifications proposed by Palla et al (1991) and Molinari et al (2008). We used the recently comissioned CABB backend at ATCA obtaining images with 20arcsec resolution in the 1.3cm continuum and H2O maser emission, in all targets. For the evolutionary analysis of the sources we used the millimeter continuum emission from Beltran et al (2006) and the infrared emission from the MSX Point Source Catalogue. We detect centimeter continuum emission in 88% of the observed fields with a typical rms noise level of 0.45mJy/beam. Most of the fields show a single radio continuum source, while in 20% of them we identify multiple components. A total of 214 centimeter continuum sources have been identified, likely tracing optically thin HII regions, with physical parameters typical of both extended and compact HII regions. Water maser emission was detected in 41% of the regions, resulting in a total of 85 distinct components. The low angular (20arcsec) and spectral (14km/s) resolutions do not allow a proper analysis of the water maser emission, but suffice to investigate its association with the continuum sources. We have also studied the detection rate of HII regions in the two types of IRAS sources defined by Palla et (1991) on the basis of the IRAS colours: High and Low. No significant differences are found, with large detection rates (>90%) for both High and Low sources. We classify the millimeter and infrared sources in our fields in three evolutionary stages following the scheme presented by ...Comment: 102 pages, 19 figures, 10 tables, accepted for publication in Astronomy & Astrophysic

Physical properties of high-mass clumps in different stages of evolution

(Abridged) Aims. To investigate the first stages of the process of high-mass star formation, we selected a sample of massive clumps previously observed with the SEST at 1.2 mm and with the ATNF ATCA at 1.3 cm. We want to characterize the physical conditions in such sources, and test whether their properties depend on the evolutionary stage of the clump. Methods. With ATCA we observed the selected sources in the NH3(1,1) and (2,2) transitions and in the 22 GHz H2O maser line. Ammonia lines are a good temperature probe that allow us to accurately determine the mass and the column-, volume-, and surface densities of the clumps. We also collected all data available to construct the spectral energy distribution of the individual clumps and to determine if star formation is already occurring, through observations of its most common signposts, thus putting constraints on the evolutionary stage of the source. We fitted the spectral energy distribution between 1.2 mm and 70 microns with a modified black body to derive the dust temperature and independently determine the mass. Results. The clumps are cold (T~10-30 K), massive (M~10^2-10^3 Mo), and dense (n(H2)>~10^5 cm^-3) and they have high column densities (N(H2)~10^23 cm^-2). All clumps appear to be potentially able to form high-mass stars. The most massive clumps appear to be gravitationally unstable, if the only sources of support against collapse are turbulence and thermal pressure, which possibly indicates that the magnetic field is important in stabilizing them. Conclusions. After investigating how the average properties depend on the evolutionary phase of the source, we find that the temperature and central density progressively increase with time. Sources likely hosting a ZAMS star show a steeper radial dependence of the volume density and tend to be more compact than starless clumps.Comment: Published in A&A, Vol. 556, A1

Total ozone time series analysis: a neural network model approach

International audienceThis work is focused on the application of neural network based models to the analysis of total ozone (TO) time series. Processes that affect total ozone are extremely non linear, especially at the considered European mid-latitudes. Artificial neural networks (ANNs) are intrinsically non-linear systems, hence they are expected to cope with TO series better than classical statistics do. Moreover, neural networks do not assume the stationarity of the data series so they are also able to follow time-changing situations among the implicated variables. These two features turn NNs into a promising tool to catch the interactions between atmospheric variables, and therefore to extract as much information as possible from the available data in order to make, for example, time series reconstructions or future predictions. Models based on NNs have also proved to be very suitable for the treatment of missing values within the data series. In this paper we present several models based on neural networks to fill the missing periods of data within a total ozone time series, and models able to reconstruct the data series. The results released by the ANNs have been compared with those obtained by using classical statistics methods, and better accuracy has been achieved with the non linear ANNs techniques. Different network structures and training strategies have been tested depending on the specific task to be accomplished

Kinematics of the ionized-to-neutral interfaces in Monoceros R2

Context. Monoceros R2 (Mon R2), at a distance of 830 pc, is the only ultra-compact H ii region (UC H ii) where its associated photon-dominated region (PDR) can be resolved with the Herschel Space Observatory. Aims. Our aim is to investigate observationally the kinematical patterns in the interface regions (i.e., the transition from atomic to molecular gas) associated with Mon R2. Methods. We used the HIFI instrument onboard Herschel to observe the line profiles of the reactive ions CH+, OH+ and H2O+ toward different positions in Mon R2. We derive the column density of these molecules and compare them with gas-phase chemistry models. Results. The reactive ion CH+ is detected both in emission (at central and red-shifted velocities) and in absorption (at blue-shifted velocities). OH+ is detected in absorption at both blue- and red-shifted velocities, with similar column densities. H2O+ is not detected at any of the positions, down to a rms of 40 mK toward the molecular peak. At this position, we find that the OH+ absorption originates in a mainly atomic medium, and therefore is associated with the most exposed layers of the PDR. These results are consistent with the predictions from photo-chemical models. The line profiles are consistent with the atomic gas being entrained in the ionized gas flow along the walls of the cavity of the H ii region. Based on this evidence, we are able to propose a new geometrical model for this region. Conclusions. The kinematical patterns of the OH+ and CH+ absorption indicate the existence of a layer of mainly atomic gas for which we have derived, for the first time, some physical parameters and its dynamics.Comment: 6 pages, 5 figures. Accepted for publication in A&

Synthesis, Photochemical, and Redox Properties of Gold(I) and Gold(III) Pincer Complexes Incorporating a 2,2′:6′,2″-Terpyridine Ligand Framework

Reaction of [Au(C6F5)(tht)] (tht = tetrahydrothiophene) with 2,2′:6′,2″-terpyridine (terpy) leads to complex [Au(C6F5)(η1-terpy)] (1). The chemical oxidation of complex (1) with 2 equiv of [N(C6H4Br-4)3](PF6) or using electrosynthetic techniques affords the Au(III) complex [Au(C6F5)(η3-terpy)](PF6)2 (2). The X-ray diffraction study of complex 2 reveals that the terpyridine acts as tridentate chelate ligand, which leads to a slightly distorted square-planar geometry. Complex 1 displays fluorescence in the solid state at 77 K due to a metal (gold) to ligand (terpy) charge transfer transition, whereas complex 2 displays fluorescence in acetonitrile due to excimer or exciplex formation. Time-dependent density functional theory calculations match the experimental absorption spectra of the synthesized complexes. In order to further probe the frontier orbitals of both complexes and study their redox behavior, each compound was separately characterized using cyclic voltammetry. The bulk electrolysis of a solution of complex 1 was analyzed by spectroscopic methods confirming the electrochemical synthesis of complex 2

Paleolítico médio e superior em Portugal : datas 14C, estado actual dos conhecimentos, síntese e discussão

No âmbito des pesquisas do CEPUNL sobre o Paleolítico médio e superior foram obtidas novas datas de radiocarbono em situações bem definidas do ponto de vista estratigráfico; com outras, permitem uma visão cronológica global aproximada. As datas não parecem distribuir-se ao longo dos tempos de modo aleatório. No estado actual dos conhecimentos, parecem corresponder a vários conjuntos: (a) 14000 a 15000 anos BP, Solutrense superior; (b) cerca de 20 000 BP, Solutrense; (c) com datas cerca de 25000 BP, já Solutrense, e, a pouco mais de 26000 BP, ainda Musrierense; (d) entre 29 000 e 31 000 BP, Mustierense. Demonstra-se a persistência de Mustierense muito após o limite admitido; cerca de 34 000 BP - e, por conseguinte, a dos seus autores neandertalianos. Pela primeira vez, foi possível a datação do limite cronológico superior do terraço marinho de 5-8 mettos (Tirreniano III) da Arrábida, bem como de jazidas sem indústrias ou com indústrias incaracterísticas. As datas obtidas permitem correlacionar jazidas e depósitos com episódios da última glaciação. Parece haver nítida correlação entre a ocupação de grutas e abrigos pelo Homem e episódios de clima mais desfavorável.New radiocarbon measuremenrs were obtained from middle and upper Paleolithic sites currenrly under research by the CEPUNL, in well defined stratigraphical situations. Wirh other dates, they yield an approximarive chronological global view. Measurement distriburion in function of time does not seem to be an hazardous one. ln rhe actual status of our knowledge, rhis disrriburion seems ro fit in some assemblages: (a) 14000 to 15000 BP, Solurrean; (b) about 20 000 BP, Solucrean; (c) árca 25 000 BP, already Solutrean, and slighdy older than 26 000 BP, still Moust~rian; (d) berween 29 000 and 31 000 BP, Mousterian. The persistance of Mousterian much later than its acknowledged upper limit ar about 34 000 BP (and hence the survival of its neanderrhalian authors) is demonstrated. For the first time ir has been possible ro ascercain rhe upper time limit of the marine 5-8 metres raised beach (Tyrrhenian III) at Serra da Arrábida, and also rhe age of archaeological sires wirhour stone arrifacrs, or wirh uncharacteristic ones. The obtained measurements allow us to correlate localities and sedimencary units wirh lasr glaciation events. There seems to have been a distinct correlation berween cave and shelter human occupation and events marked by rhe worsening of climare.Dans le cadre des recherches du CEPUNL sur le Paléolithique moyen et supérieur ont été· obtenues de nouvelles dares 14C correspondant à des situarions bien définies du point de vue srrarigraphique; avec d'autres, elles permeccent une vision globale apptoximative de la chronologie. La discribution des dates en fonction des temps ne parait pas alléatoire. Dans I' état aCtuei des connaissances, certe discribution semble correspondre à quelques ensembles: (a) 14000 à 15 000 ans BP, Solutréen supérieur; (b) environ 20000 BP, Solutréen; (c) árca 25000 BP, Solurréen déjà, er avec un peu plus de 26 000 BP, Moustérien (encore); (d) enrre 29 000 et 31 000 BP, Moustérien. La persistance de Moustérien bien apres la date limite admise (34 000 BP environ) - et donc celle de ses auteurs neanderthaliens - est démontrée. Pour la premiere fois ii a éré possible de darer la limite chronologique supérieure de la terrasse marine de 5-8 merres (Tyrrhénien III) dans la Serra da Arrábida, ainsi que des sites dépourvus d'indusrries ou ayant livré des industries incaractéristiques. Les dates obtenues permettenr de corréler des gisements er dépôts avec des épisodes de la derniere glaciation. II semble avoir eu une nette correspondance enrre I'occupation de grottes et abris par I'Homme et des épisodes à climar plus défavorable

The first CO+ image: Probing the HI/H2 layer around the ultracompact HII region Mon R2

The CO+ reactive ion is thought to be a tracer of the boundary between a HII region and the hot molecular gas. In this study, we present the spatial distribution of the CO+ rotational emission toward the Mon R2 star-forming region. The CO+ emission presents a clumpy ring-like morphology, arising from a narrow dense layer around the HII region. We compare the CO+ distribution with other species present in photon-dominated regions (PDR), such as [CII] 158 mm, H2 S(3) rotational line at 9.3 mm, polycyclic aromatic hydrocarbons (PAHs) and HCO+. We find that the CO+ emission is spatially coincident with the PAHs and [CII] emission. This confirms that the CO+ emission arises from a narrow dense layer of the HI/H2 interface. We have determined the CO+ fractional abundance, relative to C+ toward three positions. The abundances range from 0.1 to 1.9x10^(-10) and are in good agreement with previous chemical model, which predicts that the production of CO+ in PDRs only occurs in dense regions with high UV fields. The CO+ linewidth is larger than those found in molecular gas tracers, and their central velocity are blue-shifted with respect to the molecular gas velocity. We interpret this as a hint that the CO+ is probing photo-evaporating clump surfaces.Comment: The main text has 4 pages, 2 pages of Appendix, 4 figures, 1 table. Accepted for publication in Astronomy and Astrophysics letter

INDIGO : better geomagnetic observatories where we need them

The INDIGO project aims to improve the global coverage of digital observatories by deploying digital magnetometer systems in: i) Observatories where existing analog recording equipment is in need of upgrading. ii) Newly established digital observatories. iii) Existing digital observatories for the purpose of quality control and redundancy. In implementing the project and selecting suitable sites, special attention is paid to parts of the Earth devoid of magnetic observatories, increasing the reliability and long-term operation of existing observatories and cost-effective use of local resources. The Poster reviews the current status of the project. We examine the different steps and initiatives taken since the initiation of INDIGO in 2004 and assess their effectiveness in achieving progress towards our aims of improving global coverage and enhanced data quality