High Spectral and Spatial Resolution Observations of the PDR Emission in the NGC2023 Reflection Nebula with SOFIA and APEX

We have mapped the NGC 2023 reflection nebula in [CII] and CO(11--10) with the heterodyne receiver GREAT on SOFIA and obtained slightly smaller maps in 13CO(3--2), CO(3--2), CO(4--3), CO(6--5), and CO(7--6) with APEX in Chile. We use these data to probe the morphology, kinematics, and physical conditions of the C II region, which is ionized by FUV radiation from the B2 star HD37903. The [CII] emission traces an ellipsoidal shell-like region at a position angle of ~ -50 deg, and is surrounded by a hot molecular shell. In the southeast, where the C II region expands into a dense, clumpy molecular cloud ridge, we see narrow and strong line emission from high-J CO lines, which comes from a thin, hot molecular shell surrounding the [CII] emission. The [CII] lines are broader and show photo evaporating gas flowing into the C II region. Based on the strength of the [13CII] F=2--1 line, the [CII] line appears to be somewhat optically thick over most of the nebula with an optical depth of a few. We model the physical conditions of the surrounding molecular cloud and the PDR emission using both RADEX and simple PDR models. The temperature of the CO emitting PDR shell is ~ 90 -- 120 K, with densities of 10^5 -- 10^6 cm^-3, as deduced from RADEX modeling. Our PDR modeling indicates that the PDR layer where [CII] emission dominates has somewhat lower densities, 10^4 to a few times 10^5 cm^-3Comment: Accepted by A&

Habitat Use, Phenology, And Gregariousness Of The Neotropical Psocopteran Cerastipsocus Sivorii (psocoptera: Psocidae)

A field account of the behavior and ecology of the gregarious and corticolous psocopteran Cerastipsocus sivorii is presented. The study was conducted from February to November 2003 on the campus of the Universidade Estadual de Campinas, state of São Paulo, southeastern Brazil. There was a strong positive correlation between the relative abundance of host tree species and their respective frequency of occupation by C. sivorii, suggesting that trees were used according to their availability in the study site. The phenology of C. sivorii is seasonal, with nymphs peaking in May and October, and teneral adults peaking in February, June, and October. The factors determining the variation in population density in psocopterans are poorly understood, but our data show that climatic variables, such as rainfall and temperature do not influence the phenology of C. sivorii. The individuals of C. sivorii remain together through the entire nymphal phase, resting, moving on the tree surface (mainly on bark, but occasionally on leaf petioles) and grazing in groups. Teneral adults within an aggregation usually dispersed a few days after molting. Nearly 50% of the aggregations had up to 90 individuals, but large groups presenting 240 individuals or more were also frequent, comprising 10% of all aggregations found in the field. When a moving aggregation encountered another one, they occasionally either interchanged individuals or merged into a single large group. More rarely, large aggregations divided into two groups. We suggest that gregariousness in C. sivorii is a behavioral strategy that confers protection against predation and reduces body water loss.493197214Baz, A., Observations on the biology and ecology of Psocoptera found in different kinds of leaf litter in East-Central Spain (1991) Pedobiologia, 35, pp. 89-100Baz, A., Phenology and crypsis as possible determinants of habitat selection in populations of Hemineura bigoti from central Spain (Psocoptera: Elipsocidae) (1992) Entomologia Generalis, 17, pp. 293-298Baz, A., Diversidad y abundancia de los psocópteros frondícolas y corticícolas en el sistema Ibérico Meridional (España Central) (1995) Annales de la Societé Entomologique de France, 31, pp. 71-83Broadhead, E., Psocid fauna of larch trees in Northern England - an ecological study of mixed species population exploiting a common resource (1958) Journal of Animal Ecology, 27, pp. 217-263Broadhead, E., Wapshere, A.J., Mesopsocus populations on larch in England -the distribution and dynamics of two closely-related coexisting species of Psocoptera sharing the same food resource (1966) Ecological Monographs, 36, pp. 326-388Chivers, D.P., Kiesecker, J.M., Anderson, M.T., Wildy, E.L., Blaustein, A.R., Avoidance response of a terrestrial salamander (Ambystoma macrodactylum) to chemical alarm cues (1996) Journal of Chemical Ecology, 22, pp. 1709-1716Daly, H.V., Doyen, J.T., Purcell, A.H., (1998) Introduction to Insect Biology and Diversity, , 2nd ed. New York: Oxford University PressDanks, H.V., Modification of adverse conditions by insects (2002) Oikos, 99, pp. 10-24Devine, T.L., The dynamics of body water in the booklouse Liposcelis bostrychophilus (Badonnel) (1982) The Journal of Experimental Zoology, 222, pp. 335-347Hamilton, W.D., Geometry for the selfish herd (1971) Journal of Theoretical Biology, 31, pp. 295-311Krebs, J.R., Davies, N.B., (1993) An Introduction to Behavioural Ecology, , 3rd ed. Oxford: Blackwell Scientific PublicationsLienhard, C., Smithers, C.N., (2002) Psocoptera (Insecta) : World Catalogue and Bibliography. Instrumenta Biodiversitatis V, , Muséum d'Histoire Naturelle, GenèveMartin, P., Bateson, P., (1986) Measuring Behaviour: An Introductory Guide, , New York: Cambridge University PressMockford, E.L., Systematics of the New World genera of Cerastipsocini and species of Psococerastis Pearman (Psocoptera: Psocidae: Cerastipsocinae) (1981) Transactions of the American Entomological Society, 107, pp. 249-298Mockford, E.L., North American Psocoptera (1993) Fauna and Flora Handbook, (10). , Sandhill Crane Press Inc. Gainesville, Florida. Leiden, The NetherlandsNew, T.R., The relative abundance of some British Psocoptera on different species of trees (1970) Journal of Animal Ecology, 39, pp. 521-540New, T.R., Species of Lachesilla associated with palm trees in Central Brazil (1971) Zoological Journal of the Linnean Society, 50, pp. 431-437New, T.R., Communal oviposition and egg-brooding in a psocid, Peripsocus nitens (Insecta: Psocoptera) in Chile (1985) Journal of Natural History, 19, pp. 419-423New, T.R., Biology of Psocoptera (1987) Oriental Insects, 21, pp. 1-109New, T.R., Adis, J.U., Morais, J.W., Rodrigues, J.M.G., Notes on phenology and abundance of Psocoptera from primary and secondary dryland forest in Central Amazônia, Brazil (1991) Studies on Neotropical Fauna and Environment, 26, pp. 243-247New, T.R., Collins, N.M., Herd-grazing in tropical Psocoptera (1987) Entomologists Monthly Magazine, 123, pp. 229-230Rees, D.P., Walker, A.J., The effect of temperature and relative humidity on population growth of three Liposcelis species (Psocoptera, Liposcelidae) infesting stored products in tropical countries (1990) Bulletin of Entomological Research, 80, pp. 353-358Rudolph, D., Occurrence, properties and biological implications of the active uptake of water vapour from atmosphere in Psocoptera (1982) Journal of Insect Physiology, 28, pp. 111-121Thornton, I.W.B., The geographical and ecological distribution of arboreal Psocoptera (1985) Annual Review of Entomology, 30, pp. 175-196Treherne, J.E., Foster, W.A., Group transmission of predation avoidance behaviour in a marine insect: The Trafalgar effect (1981) Animal Behaviour, 29, pp. 911-917Turner, B.D., The population dynamics of tropical arboreal Psocoptera (Insecta) on two species of conifers in the Blue Mountains, Jamaica (1974) Journal of Animal Ecology, 43, pp. 323-337Turner, B.D., Broadhead, E., The diversity and distribution of psocid populations on Mangifera indica, L. in Jamaica and their relationship to altitude and micro-epiphyte diversity (1974) Journal of Animal Ecology, 43, pp. 173-190Vanini, F., Bonato, V., Freitas, A.V.L., Polyphenism and population biology of Eurema elathea (Lepidoptera: Pieridae) in a disturbed environment in Tropical Brazil (2000) Journal of Lepidopterist's Society, 53, pp. 159-168Wang, J.J., Tsai, J.H., Zhao, Z.M., Li, L.S., Interactive effects of temperature and controlled atmosphere at biologically relevant levels on development on the reproduction of the psocid, Liposcelis bostrichophila Badonnel (Psocoptera: Liposcelididae) (2001) International Journal of Pest Management, 47, pp. 55-62Wolda, H., Broadhead, E., Seasonality of Psocoptera in two tropical forests in Panama (1985) Journal Animal Ecology, 54, pp. 519-530Wolda, W., Insect seasonality: Why? (1988) Annual Review of Ecology and Systematics, 19, pp. 1-1

Las palabras de Max: un cuento moral

Requena, G.; Fernández Requena, A. (1978). Las palabras de Max: un cuento moral. La mirada. (2):26-28. http://hdl.handle.net/10251/41559.Importación Masiva2628

The largest oxigen bearing organic molecule repository

We present the first detection of complex aldehydes and isomers in three typical molecular clouds located within 200pc of the center of our Galaxy. We find very large abundances of these complex organic molecules (COMs) in the central molecular zone (CMZ), which we attribute to the ejection of COMs from grain mantles by shocks. The relative abundances of the different COMs with respect to that of CH3OH are strikingly similar for the three sources, located in very different environments in the CMZ. The similar relative abundances point toward a unique grain mantle composition in the CMZ. Studying the Galactic center clouds and objects in the Galactic disk having large abundances of COMs, we find that more saturated molecules are more abundant than the non-saturated ones. We also find differences between the relative abundance between COMs in the CMZ and the Galactic disk, suggesting different chemical histories of the grain mantles between the two regions in the Galaxy for the complex aldehydes. Different possibilities for the grain chemistry on the icy mantles in the GC clouds are briefly discussed. Cosmic rays can play an important role in the grain chemistry. With these new detections, the molecular clouds in the Galactic center appear to be one of the best laboratories for studying the formation of COMs in the Galaxy.Comment: 20 pages, 4 figures, accepted in Ap

Effect of solution heat treatment on the internal architecture and compressive strength of an AlMg4.7Si8 alloy

The evolution of the microstructure of an AlMg4.7Si8 alloy is investigated by scanning electron microscopy and ex situ synchrotron tomography in as-cast condition and subsequent solution treatments for 1 h and 25 h at 540 °C, respectively. The eutectic Mg2Si phase, which presents a highly interconnected structure in the as-cast condition, undergoes significant morphological changes during the solution heat treatment. Statistical analyses of the particle distribution, the sphericity, the mean curvatures and Gaussian curvatures describe the disintegration of the interconnected seaweed-like structure followed by the rounding of the disintegrated fractions of the eutectic branches quantitatively. The ternary eutectic Si resulting from the Si-surplus to the stoichiometric Mg2Si ratio of the alloy undergoes similar changes. The morphological evolution during solution heat treatment is correlated with results of elevated temperature compression tests at 300 °C. The elevated temperature compressive strength is more sensitive to the degree of interconnectivity of the three dimensional Mg2Si network than to the shape of the individual particles. © 2013 Elsevier B.V. All rights reserved

Relato y autor: (con Providence de Resanais como campo de aplicación)

Requena, JG. (1978). Relato y autor: (con Providence de Resanais como campo de aplicación). La mirada. (2):58-64. http://hdl.handle.net/10251/41567.Importación Masiva5864

Sub-micrometre holotomographic characterisation of the effects of solution heat treatment on an AlMg7.3Si3.5 alloy

A strip cast AlMg7.3Si3.5 alloy is investigated by sub-micrometre holotomographic analysis achieving a voxel size of (60 nm)(3) by cone beam magnification of the focused synchrotron beam using Kirkpatrick-Baez mirrors. The three-dimensional microstructure of the same specimen volume in the as-cast state is compared with that after exposure to 540 degrees C for 30 min resolving microstructural features down to 180 nm. The three-dimensional analysis of the architecture of the eutectic Mg2Si and the Fe-aluminides reveals how the as-cast microstructure changes during the solution treatment. The alloy in the as-cast condition contains a highly interconnected seaweed-like Mg2Si eutectic. The level of three-dimensional interconnectivity of the Mg2Si eutectic phase decreases by only partial disintegration during the heat treatment correcting the two-dimensional metallographic impression of isolated round particles. Statistical analyses of the particle distribution, sphericity, mean curvatures and Gaussian curvatures describe quantitatively the architectural changes of the Mg2Si phase. This explains the decrease of the high temperature strength of the alloy by the solution treatment tested in hot compression. (C) 2012 Elsevier B.V. All rights reserved

Burguesía y aparato cinematográfico

Requena, JG. (1978). Burguesía y aparato cinematográfico. La mirada. (1):13-21. http://hdl.handle.net/10251/41546.Importación Masiva1321

Elementos para el análisis de un aparato ideológico

Requena, JG. (1978). Elementos para el análisis de un aparato ideológico. La mirada. (4):41-45. http://hdl.handle.net/10251/41588.Importación Masiva4145