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Sample records for atacama desert coast

  1. The Solar Spectrum in the Atacama Desert

    OpenAIRE

    R.R Cordero; Damiani, A.; G. Seckmeyer; Jorquera, J.; Caballero, M; Rowe, P.; Ferrer, J; Mubarak, R.; Carrasco, J.; R. Rondanelli; Matus, M.; Laroze, D.

    2016-01-01

    The Atacama Desert has been pointed out as one of the places on earth where the highest surface irradiance may occur. This area is characterized by its high altitude, prevalent cloudless conditions and relatively low columns of ozone and water vapor. Aimed at the characterization of the solar spectrum in the Atacama Desert, we carried out in February-March 2015 ground-based measurements of the spectral irradiance (from the ultraviolet to the near infrared) at seven locations that ranged from ...

  2. EVIDENCIA DE TEMPRANAS MANIFESTACIONES RUPESTRES EN LA COSTA DEL DESIERTO DE ATACAMA (25° S (Evidence of Early Rock Art on the Coast of the Atacama Desert (25° S

    Directory of Open Access Journals (Sweden)

    José Castelleti

    2015-10-01

    Full Text Available Los análisis llevados a cabo sobre pictografías rupestres de la comuna de Taltal, en la costa del desierto de Atacama en Chile, tradicionalmente descritas como «estilo El Médano», han permitido datarlas por AMS en 7882 ± 160 A. P. (7022-6509 a. C. 68 %, 7172-6412 a. C. 95 %, hacia el traslape Arcaico Temprano/Medio; información corroborada con la datación arqueomagnética llevada a cabo sobre muestras del mismo panel radiocarbónicamente fechado, la cual arroja rangos de 9132-9065 a. C., 6492-6426 a. C. y 5203-5114 a. C. (65 % de confianza. Las peculiaridades tecnoeconómicas que evidencian la conformación de la mezcla de las pinturas rupestres, permiten interpretar para la zona el desarrollo de un notable nodo ocupacional arcaico, plenamente adaptado al bioclima costero; conformado por grupos humanos que, si bien diferenciados localmente, también reprodujeron una identidad común centrada en la simbología del color rojo obtenido de la hematita, arcillas y, probablemente también, de arbustos locales como el churco, parte crucial en la materialización de metáforas de animales y escenas marinas socialmente compartidas y en la semantización del espacio. ENGLISH: AMS dating of cave art located in the Taltal district, on the coast of the Atacama desert in Chile, produced dates of 7882 ± 160 BP (7022-6509 BC 68%, 7172-6412 BC 95%, placing it in the Early/Middle Archaic period. This finding is further supported by archaeomagnetic dates on samples from the same panel, which produced three time intervals all consistent with the AMS dates: 9132-9065 BC, 6492-6426 BC, and 5203-5114 BC (65% confidence. Techno-economic analysis of the cave paintings suggests the Taltal area was an important Archaic settlement cluster, inhabited by different groups who were fully adapted to the coastal bioregion and who shared a common symbolic identity. The color red, produced from hematite, clays, and probably local shrubs such as churco, played a crucial

  3. The Solar Spectrum in the Atacama Desert

    Science.gov (United States)

    Cordero, R. R.; Damiani, A.; Seckmeyer, G.; Jorquera, J.; Caballero, M.; Rowe, P.; Ferrer, J.; Mubarak, R.; Carrasco, J.; Rondanelli, R.; Matus, M.; Laroze, D.

    2016-03-01

    The Atacama Desert has been pointed out as one of the places on earth where the highest surface irradiance may occur. This area is characterized by its high altitude, prevalent cloudless conditions and relatively low columns of ozone and water vapor. Aimed at the characterization of the solar spectrum in the Atacama Desert, we carried out in February-March 2015 ground-based measurements of the spectral irradiance (from the ultraviolet to the near infrared) at seven locations that ranged from the city of Antofagasta (on the southern pacific coastline) to the Chajnantor Plateau (5,100 m altitude). Our spectral measurements allowed us to retrieve the total ozone column, the precipitable water, and the aerosol properties at each location. We found that changes in these parameters, as well as the shorter optical path length at high-altitude locations, lead to significant increases in the surface irradiance with the altitude. Our measurements show that, in the range 0-5100 m altitude, surface irradiance increases with the altitude by about 27% in the infrared range, 6% in the visible range, and 20% in the ultraviolet range. Spectral measurements carried out at the Izaña Observatory (Tenerife, Spain), in Hannover (Germany) and in Santiago (Chile), were used for further comparisons.

  4. The Solar Spectrum in the Atacama Desert.

    Science.gov (United States)

    Cordero, R R; Damiani, A; Seckmeyer, G; Jorquera, J; Caballero, M; Rowe, P; Ferrer, J; Mubarak, R; Carrasco, J; Rondanelli, R; Matus, M; Laroze, D

    2016-01-01

    The Atacama Desert has been pointed out as one of the places on earth where the highest surface irradiance may occur. This area is characterized by its high altitude, prevalent cloudless conditions and relatively low columns of ozone and water vapor. Aimed at the characterization of the solar spectrum in the Atacama Desert, we carried out in February-March 2015 ground-based measurements of the spectral irradiance (from the ultraviolet to the near infrared) at seven locations that ranged from the city of Antofagasta (on the southern pacific coastline) to the Chajnantor Plateau (5,100 m altitude). Our spectral measurements allowed us to retrieve the total ozone column, the precipitable water, and the aerosol properties at each location. We found that changes in these parameters, as well as the shorter optical path length at high-altitude locations, lead to significant increases in the surface irradiance with the altitude. Our measurements show that, in the range 0-5100 m altitude, surface irradiance increases with the altitude by about 27% in the infrared range, 6% in the visible range, and 20% in the ultraviolet range. Spectral measurements carried out at the Izaña Observatory (Tenerife, Spain), in Hannover (Germany) and in Santiago (Chile), were used for further comparisons. PMID:26932150

  5. Tree establishment along an ENSO experimental gradient in the Atacama desert

    NARCIS (Netherlands)

    Squeo, F.A.; Holmgren, M.; Jimenez, L.; Alban, L.; Reyes, J.; Gutierrez, J.R.

    2007-01-01

    Questions: (1) What are the roles of regional climate and plant growth rate for seedling establishment during ENSO rainy pulses along the western coast of South America? (2) What is the water threshold for tree seedling establishment in these arid ecosystems? Location: Atacama Desert, western South

  6. Neogene climate change and uplift in the Atacama Desert, Chile

    Science.gov (United States)

    Rech, Jason A.; Currie, Brian S.; Michalski, Greg; Cowan, Angela M.

    2006-09-01

    The relationship between Andean uplift and extreme desiccation of the west coast of South America is important for understanding the interplay between climate and tectonics in the Central Andes, yet it is poorly understood. Here we use soil morphological characteristics, salt chemistry, and mass independent fractionation anomalies (Δ17O values) in dated paleosols to reconstruct a middle Miocene climatic transition from semiaridity to extreme hyperaridity in the Atacama Desert. Paleosols along the southeastern margin of the Calama Basin change from calcic Vertisols with root traces, slickensides, and gleyed horizons to an extremely mature salic Gypsisol with pedogenic nitrate. We interpret this transition, which occurred between 19 and 13 Ma, to represent a change in precipitation from >200 mm/yr to 2 km; the uplift blocked moisture from the South American summer monsoon from entering the Atacama. The mid-Miocene Gypsisol with pedogenic nitrate is located at elevations between 2900 and 3400 m in the Calama Basin, significantly higher than modern nitrate soils, which occur below ˜2500 m. Modern and Quaternary soils in this elevation zone contain soil carbonate and lack pedogenic gypsum and nitrate. We infer that >900 m of local surface uplift over the past 10 m.y. displaced these nitrate paleosols relative to modern nitrate soils and caused a return to wetter conditions in the Calama Basin by decreasing local air temperatures and creating an orographic barrier to Pacific air masses.

  7. Ancient photosynthetic eukaryote biofilms in an Atacama Desert coastal cave

    Science.gov (United States)

    Azua-Bustos, A.; Gonzalez-Silva, C.; Mancilla, R.A.; Salas, L.; Palma, R.E.; Wynne, J.J.; McKay, C.P.; Vicuna, R.

    2009-01-01

    Caves offer a stable and protected environment from harsh and changing outside prevailing conditions. Hence, they represent an interesting habitat for studying life in extreme environments. Here, we report the presence of a member of the ancient eukaryote red algae Cyanidium group in a coastal cave of the hyperarid Atacama Desert. This microorganism was found to form a seemingly monospecific biofilm growing under extremely low photon flux levels. Our work suggests that this species, Cyanidium sp. Atacama, is a new member of a recently proposed novel monophyletic lineage of mesophilic "cave" Cyanidium sp., distinct from the remaining three other lineages which are all thermo-acidophilic. The cave described in this work may represent an evolutionary island for life in the midst of the Atacama Desert. ?? Springer Science + Business Media, LLC 2009.

  8. Salt deliquescence drives photosynthesis in the hyperarid Atacama Desert.

    Science.gov (United States)

    Davila, Alfonso F; Hawes, Ian; Ascaso, Carmen; Wierzchos, Jacek

    2013-08-01

    Endolithic cyanobacteria are found in halite nodules in the hyperarid core of the Atacama Desert. Using Pulse Amplitude Modulated Fluorometry, we show here that photosynthetic systems of these cyanobacteria become active when the relative humidity rises above 70% and the salt becomes wet by way of deliquescence. This is the first evidence of active metabolism in the hyperarid core of the Atacama, and supports the view of a microbial community sustained by deliquescence. Our results expand the water activity envelope of life on Earth. PMID:23864573

  9. Biogeographic diversification in Nolana (Solanaceae), a ubiquitous member of the Atacama and Peruvian Deserts along the western coast of South America

    Institute of Scientific and Technical Information of China (English)

    Michael O. DILLON; Tieyao TU; Lei XIE; Victor QUIPUSCOA SILVESTRE; Jun WEN

    2009-01-01

    The present paper reconstructs the biogeographic diversification for Nolana L.f. (Solanaceae), a genus of 89 endemic species largely restricted to fog-dependent desert lomas formations of coastal Peru and Chile. Previous efforts have reconstructed a phylogenetic estimate for Nolana using a combination of molecular markers. Herein, we expand on those results to examine hypotheses of biogeographic origins and diversification patterns. Nolana occupies habitats within a continuous coastal desert and forms a terrestrial archipelago of discrete "islands" unique in size, topography, and species composition. Each locality contains at least one Nolana species and many contain multiple species in sympatry. The genus has a Chilean origin, with the basal clades confined to Chile with wide geographic and ecological distributions. Peru contains two strongly supported clades, suggesting two introductions with subsequent radiation. A Chilean clade of shrubby, small-flowered species appears to have had its origins from the same ancestors of the second line that radiated in Peru and northern Chile. Nolana galapagensis is endemic to over the past 4.02 mya in Nolana, in one of the driest habitats on Earth, suggest rapid adaptive radiation in several clades. Success in Nolana may be attributed to characters that confer a competitive advantage in unpredictable and water-dependent environments, such as succulent leaf anatomy and ecophysiology, and the reproductive mericarp unique to Nolana. The processes affecting or shaping the biota of western South America are discussed.

  10. Fog deposition to a Tillandsia carpet in the Atacama Desert

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    P. Osses

    2009-09-01

    Full Text Available In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. In this exploratory study we estimate the amount of water available for the ecosystem by deposition and determine the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of water. Between 31 July and 19 August 2008 approximately 2.5 L m−2 of water were made available through deposition. Whole-year deposition was estimated as 25 L m−2. Turbulent upward fluxes occurred several times during the evenings and are explained by the formation of radiation fog. In connection with that, underestimates of the deposition are assumed. More detailed studies covering various seasons and all parameters and fluxes contributing to the local energy balance are suggested. This will help to further develop understanding about the processes of (i deposition of water to the desert, and (ii intensification of advection fog through additional formation of radiation fog.

  11. Robot Science Autonomy in the Atacama Desert and Beyond

    Science.gov (United States)

    Thompson, David R.; Wettergreen, David S.

    2013-01-01

    Science-guided autonomy augments rovers with reasoning to make observations and take actions related to the objectives of scientific exploration. When rovers can directly interpret instrument measurements then scientific goals can inform and adapt ongoing navigation decisions. These autonomous explorers will make better scientific observations and collect massive, accurate datasets. In current astrobiology studies in the Atacama Desert we are applying algorithms for science autonomy to choose effective observations and measurements. Rovers are able to decide when and where to take follow-up actions that deepen scientific understanding. These techniques apply to planetary rovers, which we can illustrate with algorithms now used by Mars rovers and by discussing future missions.

  12. Biotechnological Applications Derived from Microorganisms of the Atacama Desert

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    Armando Azua-Bustos

    2014-01-01

    Full Text Available The Atacama Desert in Chile is well known for being the driest and oldest desert on Earth. For these same reasons, it is also considered a good analog model of the planet Mars. Only a few decades ago, it was thought that this was a sterile place, but in the past years fascinating adaptations have been reported in the members of the three domains of life: low water availability, high UV radiation, high salinity, and other environmental stresses. However, the biotechnological applications derived from the basic understanding and characterization of these species, with the notable exception of copper bioleaching, are still in its infancy, thus offering an immense potential for future development.

  13. Subcritical Water Extraction of Amino Acids from Atacama Desert Soils

    Science.gov (United States)

    Amashukeli, Xenia; Pelletier, Christine C.; Kirby, James P.; Grunthaner, Frank J.

    2007-01-01

    Amino acids are considered organic molecular indicators in the search for extant and extinct life in the Solar System. Extraction of these molecules from a particulate solid matrix, such as Martian regolith, will be critical to their in situ detection and analysis. The goals of this study were to optimize a laboratory amino acid extraction protocol by quantitatively measuring the yields of extracted amino acids as a function of liquid water temperature and sample extraction time and to compare the results to the standard HCl vapor- phase hydrolysis yields for the same soil samples. Soil samples from the Yungay region of the Atacama Desert ( Martian regolith analog) were collected during a field study in the summer of 2005. The amino acids ( alanine, aspartic acid, glutamic acid, glycine, serine, and valine) chosen for analysis were present in the samples at concentrations of 1 - 70 parts- per- billion. Subcritical water extraction efficiency was examined over the temperature range of 30 - 325 degrees C, at pressures of 17.2 or 20.0 MPa, and for water- sample contact equilibration times of 0 - 30 min. None of the amino acids were extracted in detectable amounts at 30 degrees C ( at 17.2 MPa), suggesting that amino acids are too strongly bound by the soil matrix to be extracted at such a low temperature. Between 150 degrees C and 250 degrees C ( at 17.2 MPa), the extraction efficiencies of glycine, alanine, and valine were observed to increase with increasing water temperature, consistent with higher solubility at higher temperatures, perhaps due to the decreasing dielectric constant of water. Amino acids were not detected in extracts collected at 325 degrees C ( at 20.0 MPa), probably due to amino acid decomposition at this temperature. The optimal subcritical water extraction conditions for these amino acids from Atacama Desert soils were achieved at 200 degrees C, 17.2 MPa, and a water- sample contact equilibration time of 10 min.

  14. Andean uplift and Neogene climate change in the Atacama Desert

    Science.gov (United States)

    Rech, J. A.; Currie, B. S.; Jordan, T. E.

    2006-12-01

    Today the Andean Cordillera and Altiplano provide a major obstacle to atmospheric circulation over South America. The Altiplano Plateau prevents moist air masses from the Amazon Basin from reaching the Atacama Desert, causing the Atacama to be one of the driest places on Earth. Although Neogene sedimentary records from the western flank of the Andes should record the dramatic shift to hyperaridity that resulted from the growth of the Altiplano Plateau, the climatic implications of many sedimentary sequences have been difficult to decipher. The causes of the difficulties are complex, such as the relative influences of tectonics and active volcanism versus climate, and the roles of local as well as regional precipitation on groundwater and on the deposition of paludal sediments in basin centers. Over the last few years our research group has focused on using paleosols and the isotopic composition of palustrine carbonates in the Calama Basin (22°S) to try to identify a local precipitation signal and determine the onset of extreme hyperaridity as a consequence of the growth of the Altiplano. We have determined the soil morphological characteristics, salt chemistry, and mass independent fractionation anomalies (Δ17O values) in dated paleosols to reconstruct a Middle Miocene climatic transition from semi-aridity to extreme hyperaridity in the Atacama Desert. Paleosols along the southeastern margin of the Calama Basin change from calcic Vertisols with root traces, slickensides, and gleyed horizons to an extremely mature salic Gypsisol with pedogenic nitrate. We interpret this transition, which occurred between 19 and 13 Ma, to represent a change in precipitation from >200 mm/yr to Calama Basin also show a marked change during this time period. δ13C values of palustrine carbonates increase from -7 to +7? VPDB and δ18O values increases from -7 to +1? VPDB over the late to Middle Miocene time. This major trend towards more positive values is likely the result of several

  15. Xeropreservation of Functionalized Lipid Biomarkers in Hyperarid Soils in the Atacama Desert, Chile

    Science.gov (United States)

    Wilhelm, M. B.; Davila, A. F.; Eigenbrode, J. L.; Parenteau, M. N.; Jahnke, L. L.; Liu, X.; Summons, R. E.; Stamos, B. N.; Wray, J. J.; O'Reilly, S. S.; Williams, A. J.

    2016-05-01

    The preservation of lipid biomarkers was investigated in hyperarid soils with depth in the Atacama Desert. Clays sealed from rainwater for 2 Ma contained functionalized lipids, indicating that minimal degradation has occurred since their deposition.

  16. The Atacama Desert: Technical Resources and the Growing Importance of Novel Microbial Diversity.

    Science.gov (United States)

    Bull, Alan T; Asenjo, Juan A; Goodfellow, Michael; Gómez-Silva, Benito

    2016-09-01

    The Atacama Desert of northern Chile is the oldest and most arid nonpolar environment on Earth. It is a coastal desert covering approximately 180,000 km(2), and together with the greater Atacama region it comprises a dramatically wide range of ecological niches. Long known and exploited for its mineral resources, the Atacama Desert harbors a rich microbial diversity that has only recently been discovered; the great majority of it has not yet been recovered in culture or even taxonomically identified. This review traces the progress of microbiology research in the Atacama and dispels the popular view that this region is virtually devoid of life. We examine reasons for such research activity and demonstrate that microbial life is the latest recognized and least explored resource in this inspiring biome. PMID:27607552

  17. Coatings on Atacama Desert Basalt: A Possible Analog for Coatings on Gusev Plains Basalt

    Science.gov (United States)

    Sutter, B.; Golden, D. C.; Amundson, R.; Chong-Diaz, G.; Ming, D. W.

    2007-01-01

    Surface coatings on Gusev Plains basalt have been observed and may contain hematite and nanophase Fe-oxides along with enrichments in P, S, Cl, and K relative to the underlying rock. The Gusev coatings may be derived from the dissolution of adhering soil and/or parent rock along with the addition of S and Cl from outside sources. Transient water for dissolution could be sourced from melting snow during periods of high obliquity, acid fog, and/or ground water (Haskin et al., 2005). Coatings on basalt in the hyper-arid (less than 2mm y(sup -1)) Atacama Desert may assist in understanding the chemistry, mineralogy and formation mechanisms of the Gusev basalt coatings. The Atacama Desert climate is proposed to be analogous to a paleo-Mars climate that was characterized by limited aqueous activity when the Gusev coatings could have formed. The objectives of this work are to (i) determine the chemical nature and extent of surface coatings on Atacama Desert basalt, and (ii) assess coating formation mechanisms in the Atacama Desert. Preliminary backscattered electron imaging of Atacama basalt thin-sections indicated that the coatings are as thick as 20 m. The boundary between the coating and the basalt labradorite, ilmenite, and augite grains was abrupt indicating that the basalt minerals underwent no chemical dissolution. The Atacama coatings have been added to the basalt instead of being derived from basalt chemical weathering. Semi-quantitative energy dispersive spectroscopy shows the coatings to be chemically homogeneous. The coating is depleted in Ca (0.9 wt% CaO) and enriched in K (1.3 wt.% K2O) and Si (69.1 wt.% SiO2) relative to the augite and labradorite grains. A dust source enriched in Si (e.g., poorly crystalline silica) and K and depleted in Ca appears to have been added to the basalt surface. Unlike the Gusev coatings, no P, S, and Cl enrichment was observed. However, Fe (3.2 wt.% FeO) was present in the Atacama coatings suggesting the present of Fe

  18. In situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert

    OpenAIRE

    Davila, Alfonso F.; Ian eHawes; Jonathan eGarcía Araya; Diego R Gelsinger; Jocelyne eDiRuggiero; Carmen eAscaso; Anne eOsano; Jacek eWierzchos

    2015-01-01

    The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlle...

  19. Are There High Meteorite Concentrations in the Atacama Desert/Chile?

    Science.gov (United States)

    Scherer, P.; Delisle, G.

    1992-07-01

    We have visited numerous regions of the Atacama desert between Copiapo (27 degrees, 15'S) and Calama (22 degrees, 25'S) to assess their potential as a high-yield meteorite concentration surface, easily exploitable by search efforts within a reasonable time frame. According to our observations, this desert is characterized by the following features: a) A high percentage of the desert consists of sloping surfaces on which soil movement occurs, presumably by very infrequent, though heavy rain. b) Vast areas of the desert are covered by a dm-thick sand layer of dark colour. Since the sand is too coarse-grained to be transported by wind it presumably resulted from in-situ weathering of rock debris derived from nearby mountains. We suspect that impacting smaller objects can easily penetrate the sand layer. c) The sand layer is typically dotted by rocks, fist-size or smaller, that are covered by a thick layer of desert paint (reddish-brown to black colour). Most country rocks are of volcanic origin (rhyolite, andesite, basalt) and are typically of grey to black colour. A noticeable colour contrast in particular to potential stony meteorites is almost nonexistent. d) Soil salts with a potential to speed up weathering processes are ubiquitous near the surface. e) The Pampa de Mejillones, 45 km north of Antofagasta, is one of the few light-coloured areas in the Atacama desert. The surface, being of Mio-Pliocene age, consists of an almost continuous layer of light-brown fossil shells (bivalves and gastropodes). Fluvially transported dark rocks from adjacent outcrops rest on top. The latter material is covered again by desert paint. Few meteorite discoveries have been reported from this area (Pampa (a),(b),(c)). f) Numerous old tire tracks, in particular around mines in operation, crisscross most areas of the Atacama. Undetected objects such as large masses of iron bodies are not likely to have remained undiscovered in great numbers any more. We conclude that the potential of

  20. Endolithic Cyanobacteria in Halite Rocks from the Hyperarid Core of the Atacama Desert

    Science.gov (United States)

    Wierzchos, Jacek; Ascaso, Carmen; McKay, Christopher P.

    2006-06-01

    In the driest parts of the Atacama Desert there are no visible life forms on soil or rock surfaces. The soil in this region contains only minute traces of bacteria distributed in patches, and conditions are too dry for cyanobacteria that live under translucent stones. Here we show that halite evaporite rocks from the driest part of the Atacama Desert are colonized by cyanobacteria. This colonization takes place just a few millimeters beneath the rock surface, occupying spaces among salt crystals. Our work reveals that these communities are composed of extremely resistant Chroococcidiopsis morphospecies of cyanobacteria and associated heterotrophic bacteria. This newly discovered endolithic environment is an extremely dry and, at the same time, saline microbial habitat. Photosynthetic microorganisms within dry evaporite rocks could be an important and previously unrecognized target for the search for life within our Solar System.

  1. Novel water source for endolithic life in the hyperarid core of the Atacama Desert

    OpenAIRE

    Wierzchos, J.; Davila, A. F.; I. M. Sánchez-Almazo; Hajnos, M.; R. Swieboda; Ascaso, C.

    2012-01-01

    The hyperarid core of the Atacama Desert, Chile, is possibly the driest and most life-limited place on Earth, yet endolithic microorganisms thrive inside halite pinnacles that are part of ancient salt flats. The existence of this microbial community in an environment that excludes any other life forms suggests biological adaptation to high salinity and desiccation stress, and indicates an alternative source of water for life other than rainfall, fog or dew. Here, we show tha...

  2. Mid-Holocene Climate and Culture Change in the Atacama Desert, Northern Chile

    Science.gov (United States)

    Grosjean, Martin; Núñez, Lautaro; Cartajena, Isabel; Messerli, Bruno

    1997-09-01

    Twenty archaeological campsites intercalated between more than 30 debris flows caused by heavy rainfall events between 6200 and 3100 14C yr B.P. have recently been discovered at Quebrada Puripica in the Atacama Desert of northern Chile. This record provides detailed information about extreme, short-lived climatic events during the hyperarid mid-Holocene period. For the first time, we found evidence of continuous human occupation in this area, filling the regional hiatus in the Atacama basin ("Silencio Arqueologico") between 8000 and 4800 14C yr B.P. The transformation of Early Archaic hunters into the complex Late Archaic cultural tradition was an adaptive process. During this time, the site was a local ecological refuge with abundant resources in a generally hostile environment.

  3. In situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert.

    Science.gov (United States)

    Davila, Alfonso F; Hawes, Ian; Araya, Jonathan G; Gelsinger, Diego R; DiRuggiero, Jocelyne; Ascaso, Carmen; Osano, Anne; Wierzchos, Jacek

    2015-01-01

    The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlled laboratory experiments, we show that this endolithic community is capable of carbon fixation both through oxygenic photosynthesis and potentially ammonia oxidation. We also present evidence that photosynthetic activity is finely tuned to moisture availability and solar insolation and can be sustained for days, and perhaps longer, after a wetting event. This is the first demonstration of in situ active metabolism in the hyperarid core of the Atacama Desert, and it provides the basis for proposing a self-contained, endolithic community that relies exclusively on non-rainfall sources of water. Our results contribute to an increasing body of evidence that even in hyperarid environments active metabolism, adaptation, and growth can occur in highly specialized microhabitats. PMID:26500612

  4. In situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert

    Directory of Open Access Journals (Sweden)

    Alfonso F Davila

    2015-10-01

    Full Text Available The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlled laboratory experiments, we show that this endolithic community is capable of carbon fixation both through oxygenic photosynthesis and potentially ammonia oxidation. We also present evidence that photosynthetic activity is finely tuned to moisture availability and solar insolation and can be sustained for days, and perhaps longer, after a wetting event. This is the first demonstration of in situ active metabolism in the hyperarid core of the Atacama Desert, and it provides the basis for proposing a self-contained, endolithic community that relies exclusively on non-rainfall sources of water. Our results contribute to an increasing body of evidence that even in hyperarid environments active metabolism, adaptation and growth can occur in highly specialized microhabitats.

  5. A new freshwater snail (Caenogastropoda: Cochliopidae) from the Atacama Desert, northern Chile.

    Science.gov (United States)

    Collado, Gonzalo A

    2015-03-02

    In the family Cochliopidae, Heleobia Stimpson, 1865 is the most speciose genus in South America, with about 90 species (Hershler & Thompson 1992; Cazzaniga 2011). A recent molecular and morphological analysis performed in northern Chile (Atacama Desert) showed that the previously undescribed springsnails from Aguada de Chorrillos belong to Heleobia (Collado et al. 2013). In this study I formally describe this new species. Although this paper does not treat morphology in detail, the anatomical characters, in combination with the previously published molecular data provides a strong basis for recognizing this population as a distinct species.

  6. Calcium Sulfate in Atacama Desert Basalt: A Possible Analog for Bright Material in Adirondack Basalt, Gusev Crater

    Science.gov (United States)

    Sutter, B.; Golden, D. C.; Amundson, R.; Chong-Diaz, G.; Ming, D. W.

    2007-01-01

    The Atacama Desert in northern Chile is one of the driest deserts on Earth (calcium sulfate (Ca-SO4) which was later confirmed by SEM/EDS analysis. This work examines the Ca-SO4 of Atacama basalt in an effort to provide insight into the possible nature of the bright material in the Adirondack basalt of Gusev Crater. The objectives of this work are to (i) discuss variations in Ca-SO4 crystal morphology in the vesicles and (ii) examine the Ca-SO4 interaction(s) with the basalt interior.

  7. Microbial colonisation of chasmoendolithic habitats in the hyper-arid zone of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    J. DiRuggiero

    2013-04-01

    Full Text Available Efforts in searching for microbial life in the driest part of Atacama Desert, Chile, revealed a small number of lithic habitats that can be considered as environmental refuges for life. In this study, we describe for the first time chasmoendolithic colonisation of fissures and cracks of rhyolite-gypsum and calcite rocks collected in the hyper-arid zone of the desert. The use of high-throughput sequencing revealed that the Atacama rock communities comprised a few dominant phylotypes and a number of less abundant taxa representing the majority of the total community diversity. The chasmoendolithic communities were dominated by Chroococcidiopsis species cyanobacteria and supported a number of heterotrophic bacterial lineages. Micro-climate data and geomorphic analysis of the mineral substrates suggested higher water availability in the calcite rocks in the form of enhanced water retention in the complex network of cracks and fissures of these rocks as well as increased occurrence of liquid water in the form of dewfall. These characteristics were associated with a diverse community of phototrophic and heterotrophic bacteria in the calcite chasmoendolithic ecosystem. This study is another example of the diversity of adaptive strategies at the limit for life and illustrates that rock colonisation is controlled by a complex set of factors.

  8. Microbial colonization of chasmoendolithic habitats in the hyper-arid zone of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    J. DiRuggiero

    2012-11-01

    Full Text Available Efforts in searching for microbial life in the driest part of Atacama Desert, Chile, revealed a small number of lithic habitats that can be considered as environmental refuges for life. In this study, we describe for the first time chasmoendolithic colonization of fissures and cracks of rhyolite-gypsum and calcite rocks collected in the hyper-arid zone of the desert. The use of high-throughput sequencing revealed that the Atacama rock communities comprised a few dominant phylotypes and a number of less abundant taxa representing the majority of the total community diversity. The chasmoendolithic communities were dominated by Chroococcidiopsis species cyanobacteria and supported a number of novel heterotrophic bacteria. Micro-climate data and geomorphic analysis of the mineral substrates suggested higher water availability in the calcite rocks in the form of enhanced water retention in the complex network of cracks and fissures of these rocks as well as increased occurrence of liquid water in the form of dewfall. These characteristics were associated with a diverse community of phototrophic and heterotrophic bacteria in the calcite chasmoendolithic ecosystem. This study is another example of the diversity of adaptive strategies at the limit for life and illustrates that rock colonization is controlled by a complex set of factors.

  9. Late Pleistocene human occupation of the hyperarid core in the Atacama Desert, northern Chile

    Science.gov (United States)

    Latorre, Claudio; Santoro, Calogero M.; Ugalde, Paula C.; Gayo, Eugenia M.; Osorio, Daniela; Salas-Egaña, Carolina; De Pol-Holz, Ricardo; Joly, Delphine; Rech, Jason A.

    2013-10-01

    Few archeological sites in South America contain uncontroversial evidence for when the first peopling of the continent occurred. Largely ignored in this debate, extreme environments are assumed either as barriers to this early wave of migration or without potential for past habitability. Here, we report on a rare 12-13 ka human occupation from Quebrada Maní (site QM12), a plantless, near rainless landscape (1240 m asl and 85 km from the Pacific Ocean) located in the hyperarid core of the Atacama Desert. This location harbored wetlands and riparian woodlands that were fed by increased rainfall further east in the central Andes during the latest Pleistocene. Excavations at QM12 yielded a diverse cultural assemblage of lithics, burned and cut bones, marine gastropods, pigments, plant fibers, and wooden artifacts alongside a prepared fireplace. Sixteen radiocarbon dates from site QM12 on charcoal, marine shells, animal dung, plant remains and wood reveal that the occupation took place between 12.8 and 11.7 ka. These results demonstrate that the Atacama Desert was not a barrier to early American settlement and dispersal, and provide new clues for understanding the cultural complexity and diversity of the peopling of South America during the Last Glacial-interglacial transition.

  10. Contrasting Imaginaries: The Atacama Desert Perceived from the Region and Observed from the Nation

    Directory of Open Access Journals (Sweden)

    González Pizarro, José Antonio

    2009-12-01

    Full Text Available The author draws on Cornelius Castoriadis’ categories to examine the social imaginaries on the Atacama Desert from the 16th to the 20th centuries. He emphasizes the manner in which different imaginaries came to be constructed historically over time to the point of bringing about a contrast between the imaginary of the country —centered on adversity, sterility and desolation, thereby projecting a textual negativity about Atacama— and that of the region, full of varying symbolisms signifying challenge, occupation and the potentiality of nature. The latter imaginary strengthened the empathy of the northern literature toward the human epic of peopling the desert.

    Basándose en las categorías de Cornelius Castoriadis, el autor examina los imaginarios sociales sobre el desierto de Atacama desde el siglo XVI hasta el XX. Pone de relieve cómo se fueron construyendo en la historia los distintos imaginarios para situarse en la contraposición entre el establecido en la nación chilena —centrado en los elementos de adversidad, esterilidad y lo inhóspito, todo lo cual proyectó una negatividad textual— y el construido en la región, repleto de variados simbolismos en torno al desafío, la ocupación y la potencialidad de la naturaleza, que afianzó la empatía de la literatura nortina con la épica humana del asentamiento en el desierto.

  11. A multi-scale approach to assess the effect of groundwater extraction on Prosopis tamarugo in the Atacama Desert

    NARCIS (Netherlands)

    Decuyper, M.; Chávez Oyanadel, R.O.; Copini, P.; Sass-Klaassen, U.G.W.

    2016-01-01

    Groundwater-dependent ecosystems occur in arid and semi-arid areas worldwide and are sensitive to changes in groundwater availability. Prosopis tamarugo Phil, endemic to the Atacama Desert, is threatened by groundwater overexploitation due to mining and urban consumption. The effect of groundwater d

  12. Fungi associated with rocks of the Atacama Desert: taxonomy, distribution, diversity, ecology and bioprospection for bioactive compounds

    Science.gov (United States)

    This study assessed the diversity of fungi living in rocks from different altitudes in the Atacama Desert, Chile. Eighty-one fungal isolates obtained were identified as 21 species of 12 genera from Ascomycota using molecular techniques. Cladosporium halotolerans, Penicillium chrysogenum and Penicill...

  13. Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 years

    Directory of Open Access Journals (Sweden)

    E. M. Gayo

    2011-10-01

    Full Text Available Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ~21° S, 1000 m a.s.l. in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050–680, 1615–1350 and 2500–2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 years. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode, conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 years represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent

  14. Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 yr

    Directory of Open Access Journals (Sweden)

    E. M. Gayo

    2012-02-01

    Full Text Available Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ∼21° S, 1000 m a.s.l. in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050–680, 1615–1350 and 2500–2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 yr. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode, conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 yr represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence

  15. Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 yr

    Science.gov (United States)

    Gayo, E. M.; Latorre, C.; Santoro, C. M.; Maldonado, A.; de Pol-Holz, R.

    2012-02-01

    Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ∼21° S, 1000 m a.s.l.) in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050-680, 1615-1350 and 2500-2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 yr. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode), conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 yr represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence for comprehending the

  16. Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 years

    Science.gov (United States)

    Gayo, E. M.; Latorre, C.; Santoro, C. M.; Maldonado, A.; de Pol-Holz, R.

    2011-10-01

    Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ~21° S, 1000 m a.s.l.) in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050-680, 1615-1350 and 2500-2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 years. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode), conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 years represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence for comprehending the

  17. Constraining carbon sources and cycling of endolithic microbial communities in the Atacama Desert

    Science.gov (United States)

    Ziolkowski, L. A.; Slater, G. F.; Davila, A.; Wierzchos, J.

    2010-12-01

    The Atacama Desert, one of the driest places on Earth, is considered a suitable analog for the extremely arid, oxidizing conditions on the surface of Mars. Recent observations suggest the presence of evaporitic deposits on the surface of Mars, such as those found in the Atacama. Halites in the Atacama have been shown to be hygroscopic and are colonized by photosynthetic microbes. While there is considerable evidence for the decrease in abundance and diversity of microbes closer to the hyper-arid core of the Atacama, experimental studies have thus far have yet to estimate the sources of carbon to these communities and the rate at which they cycle. To address these questions, we characterized the isotopic composition (13C and 14C) microbial community biomarkers from four distinct sites in the Atacama. Sites ranged from halites in the hyper-arid core (Yungay, Salar Grande) to volcanic rock and gypsum near the Monturaqui Crater. Our analysis of the phospholipids fatty acids (PLFA) and glycolipid fatty acid (GLFA) methyl esters of the endoliths agreed with previous studies: the abundance and diversity of microbes decreases approaching the hyper-arid core. The total PLFA and GLFA concentrations were lower at Yungay than Salar Grande and higher in the gypsum and volcanic rock samples. Changes in the mole percentage distribution of the PLFA and GLFA illustrated that the endolithic communities inhabiting the volcanic rock and gypsum were more complex than those inhabiting the halites. ∂13C of both PLFA and GLFA showed that non-halite lipids were less depleted in 13C than halite-lipids. This suggested a difference in carbon source or cycling. The 14C content of PLFA and GLFA varied by up to 250 per mil. Endolith PLFA and GLFA from the gypsum had radiocarbon signatures comparable to the modern atmosphere, which suggests that the predominant source of carbon to the system is the modern atmosphere and that lipids are cycling rapidly in this system. However, at the other three

  18. The stratigraphic record of changing hyperaridity in the Atacama desert over the last 10 Ma

    Science.gov (United States)

    Sáez, Alberto; Cabrera, Lluís; Garcés, Miguel; Bogaard, Paul van den; Jensen, Arturo; Gimeno, Domingo

    2012-11-01

    New radiometric and magnetostratigraphic data from Quillagua and Calama basins (Atacama desert) indicate that the stratigraphic record over the last 10 Ma includes two hiatuses, lasting approximately 2 and 4 million years respectively. These sedimentary gaps are thought to represent prolonged periods of hyperaridity in the region, with absence of sediment production and accumulation in the central depressions. Their remarkable synchrony with Antarctic and Patagonian glacial stages, Humboldt cold current enhancement and cold upwelling waters lead us to suggest long-term climate forcing. Higher frequency climate (orbital precession and eccentricity) forcing is thought to control the sequential arrangement of the lacustrine units deposited at times of lower aridity. Hyperaridity trends appear to be modulated by the activity of the South American Summer Monsoon, which drives precipitation along the high altitude areas to the east of Atacama. This precipitation increase combined with the eastward enlargement of the regional drainage during the late Pleistocene enabled water transfer from these high altitude areas to the low lying closed Quillagua basin and resulted in the deposition of the last widespread saline lacustrine deposits in this depression, before its drainage was open to the Pacific Ocean.

  19. Preservation of Lipid Biomarkers Under Prolonged and Extreme Hyperaridity in Atacama Desert Soils

    Science.gov (United States)

    Wilhelm, Mary Beth

    2015-01-01

    Molecular biomarkers are the most direct biosignatures of life on early Earth and a key target in the search for life on Mars. Lipid biomarkers are of particular interest given their ability to survive oxidative degradation and record microbial presence and activity of microorganisms that occurred billions of years ago (Eigenbrode, 2008). Environmental conditions that suspend biotic and abiotic degradative processes prior to lithification can lead to enhanced biomolecular preservation over geological time-scales. The hyperarid core of the Atacama Desert in northern Chile offers a unique environment to investigate lipid biomarker taphonomy under extreme and prolonged dryness. We investigated the accumulation and degree of preservation of lipid biomarkers in million-year-old hyperarid soils where primarily abiotic conditions influence their taphonomy. Soils were extracted and free and membrane bound lipids were analyzed across a vertical profile of 2.5 meters in the Yungay hyper-arid core of the Atacama Desert. Due to the extremely low inventory of biomass in Atacama soils, samples were collected by scientists wearing cleanroom suits to minimize anthropogenic contamination during sampling. Fatty acids were found to be well preserved in Yungay soils, and were most abundant in the clay-rich soils at approx.2 m depth (approx.750 ng of fatty acid methyl ester/g of soil). These buried clays layers were fluvially deposited approximately 2 million years ago, and have been excluded from exposure to rainwater and modern surficial processes since their emplacement (Ewing et al., 2008). Monocarboxylic fatty acid, monohydroxy fatty acid, glycerol tetraether, and n-alkane hydrocarbon content was found to change with depth. Lipid biomarker content in deeper soil layers is suggestive of soils having been formed at a time when environmental conditions were capable of supporting active microbial communities and plants. In short, total lipid extracts reveal a remarkable degree of

  20. Preservation of Lipid Biomarkers Under Prolonged and Extreme Hyperaridity in Atacama Desert Soils

    Science.gov (United States)

    Wilhelm, M. B.; Davila, A. F.; Eigenbrode, J. L.; Parenteau, M. N.; Jahnke, L. L.; Summons, R. E.; Liu, X.; Wray, J. J.; Stamos, B.; O'Reilly, S. S.; Williams, A. J.

    2015-12-01

    Molecular biomarkers are the most direct biosignatures of life on early Earth and a key target in the search for life on Mars. Lipid biomarkers are of particular interest given their ability to survive oxidative degradation and record microbial presence and activity of microorganisms that occurred billions of years ago (Eigenbrode, 2008). Environmental conditions that suspend biotic and abiotic degradative processes prior to lithification can lead to enhanced biomolecular preservation over geological time-scales. The hyperarid core of the Atacama Desert in northern Chile offers a unique environment to investigate lipid biomarker taphonomy under extreme and prolonged dryness. We investigated the accumulation and degree of preservation of lipid biomarkers in million-year-old hyperarid soils where primarily abiotic conditions influence their taphonomy. Soils were extracted and free and membrane bound lipids were analyzed across a vertical profile of 2.5 meters in the Yungay hyper-arid core of the Atacama Desert. Due to the extremely low inventory of biomass in Atacama soils, samples were collected by scientists wearing cleanroom suits to minimize anthropogenic contamination during sampling. Fatty acids were found to be well preserved in Yungay soils, and were most abundant in the clay-rich soils at ~2 m depth (~750 ng of fatty acid methyl ester/g of soil). These buried clays layers were fluvially deposited approximately 2 million years ago, and have been excluded from exposure to rainwater and modern surficial processes since their emplacement (Ewing et al., 2008). Monocarboxylic fatty acid, monohydroxy fatty acid, glycerol tetraether, and n-alkane hydrocarbon content was found to change with depth. Lipid biomarker content in deeper soil layers is suggestive of soils having been formed at a time when environmental conditions were capable of supporting active microbial communities and plants. In short, total lipid extracts reveal a remarkable degree of lipid biomarker

  1. Phylogenetic Profiling and Diversity of Bacterial Communities in the Death Valley, an Extreme Habitat in the Atacama Desert.

    Science.gov (United States)

    Piubeli, Francine; de Lourdes Moreno, María; Kishi, Luciano Takeshi; Henrique-Silva, Flavio; García, María Teresa; Mellado, Encarnación

    2015-12-01

    The Atacama Desert, one of the driest deserts in the world, represents a unique extreme environmental ecosystem to explore the bacterial diversity as it is considered to be at the dry limit for life. A 16S rRNA gene (spanning the hyper variable V3 region) library was constructed from an alkaline sample of unvegetated soil at the hyperarid margin in the Atacama Desert. A total of 244 clone sequences were used for MOTHUR analysis, which revealed 20 unique phylotypes or operational taxonomic units (OTUs). V3 region amplicons of the 16S rRNA were suitable for distinguishing the bacterial community to the genus and specie level. We found that all OTUs were affiliated with taxa representative of the Firmicutes phylum. The extremely high abundance of Firmicutes indicated that most bacteria in the soil were spore-forming survivors. In this study we detected a narrower diversity as compared to other ecological studies performed in other areas of the Atacama Desert. The reported genera were Oceanobacillus (representing the 69.5 % of the clones sequenced), Bacillus, Thalassobacillus and Virgibacillus. The present work shows physical and chemical parameters have a prominent impact on the microbial community structure. It constitutes an example of the communities adapted to live in extreme conditions caused by dryness and metal concentrations . PMID:26543264

  2. Photovoltaic performance and LCoE comparison at the coastal zone of the Atacama Desert, Chile

    International Nuclear Information System (INIS)

    Highlights: • Two PV technologies installed at the coastal zone of Atacama Desert were studied. • The energy yield improved up to 16% after cleaning. • The monthly performance ratio was determined and analyzed for a 21 month period. • The dust accumulated on modules produced a fall of the monthly performance ratio. • The Levelized Cost of Energy (LCoE) was calculated for a dirty and clean condition. - Abstract: Two photovoltaic technologies are compared with regard to the energy yield, performance ratio and their levelized cost of energy. Plants based on amorphous/microcrystalline silicon tandem thin films and multicrystalline silicon solar cells installed at the coastal zone of the Atacama Desert, Chile, were monitored for 21 months. This region can be one of the most suitable places for the use of solar energy due to the high solar radiation levels. However, the coastal desert climate may influence the performance of photovoltaic systems. The global tilted solar irradiation reached mean values of 8.6 kW h/m2 day in summer and 6 kW h/m2 day in winter demonstrating the high irradiation available. It came out that the performance ratio is influenced by the dust accumulation and the temperature associated to this place. The performance ratio of thin films decreased due to the dust accumulation at a rate from −4.2 to −3.7%/month for decreasing temperature and from −4.8 to −4.4%/month for increasing temperature. For multicrystalline silicon modules, the degradation rates were −2.4 to −1.8%/month for decreasing temperature, and −6.2 to −3.7%/month for increasing temperature. It was concluded that the electricity costs were 14.48 cents€/kW h and 15.65 cents€/kW h for thin film and mc-Si, respectively. Thus, the thin films had more benefit after cleaning than multicrystalline modules

  3. Fog Collection and Sustainable Architecture in Atacama Coast

    Science.gov (United States)

    Suau, C.

    2010-07-01

    It is imperative to integrate renewable energy and climate into zero-carbon buildings in arid lands, particularly when it is reinforced by natural and social science-based innovation in natural and built environs. The aim is twofold: On one hand, to establish potential natural and urban habitats and their yields required in different scales of intervention and, on another hand, augment rate and yield of fog collection used for drinking and irrigation in chosen locations. The purpose of this study is to integrate zero-carbon energy, landscape and sustainable architecture as a whole and thus envision potential inhabitation through self-sufficient space-frame configurations along the coast of Tarapacá Region in Chile. In a sequential way, this study distinguishes three scales of interventions: A. Territorial scale. It consists of rural and natural zones along the shore of Tarapacá Region: Fog oases, creeks or corridors. The strategic allocation of large fog collectors can bring local agriculture back and thus stop rural emigration; and also repair existing fragile ecosystems in several fog oases by harvesting and distributing mainly crop water. B. Local scale. The space-frame fog collectors are allocated in Alto Patache (fog oasis) and Iquique city (low-income sprawl of Alto Hospicio). These artefacts can supply both water and electricity to small communities through forestation, sustainable micro-agriculture and complementary electrification. C. Domestic scale. It consists of the design of autonomous housing configuration based in polygonal space-frames. This inhabitable unit is modular, deployable and lightweight; with an adjustable polyvalent membrane which performs as water repellent skin (facing South and SW winds) and shading device facing Equator. In addition, a domestic wind turbine is installed within the structural frame to provide autonomous electrification. Water collector, filtering (purification) and irrigation network is designed with available

  4. How much Carbon is Stored in Deserts? AN Approach for the Chilean Atacama Desert Using LANDSAT-8 Products

    Science.gov (United States)

    Hernández, H. J.; Acuña, T.; Reyes, P.; Torres, M.; Figueroa, E.

    2016-06-01

    The Atacama Desert in northern Chile is known as the driest place on Earth, with an average rainfall of about 15 mm per year. Despite these conditions, it contains a rich variety of flora with hundreds of species characterised by their extraordinary ability to adapt to this extreme environment. These biotic components have a direct link to important ecosystem services, especially those related to carbon storage and sequestration. No quantitative assessment is currently available for these services and the role of the desert in this matter remains unclear. We propose an approach to estimate above-ground biomass (AGB) using Landsat-8 data, which we tested in the Taparacá region, located in the northern section of the desert. To calibrate and validate the models, we used field data from 86 plots and several spectral indexes (NDVI, EVI and SAVI) obtained from the provisional Landsat-8 Surface-reflectance products. We applied randomised branch sampling and allometry principles (non-destructive methods) to collect biomass samples for all plant biological types: wetlands, steppes, shrubs and trees. All samples were dried in an oven until they reached constant weight and the final values were used to extrapolate dry matter content (AGB) to each plot in terms of kg m-2. We used all available scenes from September 2014 to August 2015 to calculate the maximum, minimum and average value for each index in each pixel within this period. For modeling, we used the method based on classification and regression trees called random forest (RF), available in the statistical software R-Project. The explained variance obtained by the RF algorithm was around 80-85%, and it improved when a wetland vector layer was used as the predictive factor in the model to reach the range 85-90%. The mean error was 1.45 kg m-2 of dry matter. The best model was obtained using the maximum and mean values of SAVI and EVI indexes. We were able to estimate total biomass storage of around 8 million tons

  5. Novel water source for endolithic life in the hyperarid core of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    J. Wierzchos

    2012-03-01

    Full Text Available The hyperarid core of the Atacama Desert, Chile, is possibly the driest and most abiotic place on Earth, yet endolithic microorganisms thrive inside halite pinnacles that are part of ancient salt flats. The existence of this microbial community in an environment that excludes any other life forms suggests biological adaptation to high salinity and desiccation stress, and indicates an alternative source of water for life other than rainfall, fog or dew. Here we show that halite endoliths obtain liquid water through spontaneous capillary condensation at relative humidity (RH much lower than the deliquescence RH of NaCl. We describe how this condensation occurs inside nano-pores smaller than 100 nm, in a newly identified halite phase that is intimately associated with the endolithic aggregates. This nano-porous phase helps retain liquid water for long periods of time by preventing its evaporation even in conditions of utmost dryness. Our results explain how life has colonized and adapted to one of the most extreme environments on our planet, expanding the water activity envelope for life on Earth, and broadening the spectrum of possible habitats for life beyond our planet.

  6. Paleowetlands and regional climate change in the central Atacama Desert, northern Chile

    Science.gov (United States)

    Quade, Jay; Rech, Jason A.; Betancourt, Julio L.; Latorre, Claudio; Quade, Barbra; Rylander, Kate Aasen; Fisher, Timothy

    2008-01-01

    Widespread, organic-rich diatomaceous deposits are evidence for formerly wetter times along the margins of the central Atacama Desert, one of the driest places on Earth today. We mapped and dated these paleowetland deposits at three presently waterless locations near Salar de Punta Negra (24.5°S) on the western slope of the Andes. Elevated groundwater levels supported phreatic discharge into wetlands during two periods: 15,900 to ~ 13,800 and 12,700 to ~ 9700 cal yr BP. Dense concentrations of lithic artifacts testify to the presence of paleoindians around the wetlands late in the second wet phase (11,000?–9700 cal yr BP). Water tables dropped below the surface before 15,900 and since 8100 cal yr BP, and briefly between ~ 13,800 and 12,700 cal yr BP. This temporal pattern is repeated, with some slight differences, in rodent middens from the study area, in both paleowetland and rodent midden deposits north and south of the study area, and in lake level fluctuations on the adjacent Bolivian Altiplano. The regional synchroneity of these changes points to a strengthening of the South American Monsoon — which we term the "Central Andean Pluvial Event" — in two distinct intervals (15,900–13,800 and 12,700–9700 cal yr BP), probably induced by steepened SST gradients across the tropical Pacific (i.e., La Niña-like conditions).

  7. Novel water source for endolithic life in the hyperarid core of the Atacama Desert

    Science.gov (United States)

    Wierzchos, J.; Davila, A. F.; Sánchez-Almazo, I. M.; Hajnos, M.; Swieboda, R.; Ascaso, C.

    2012-06-01

    The hyperarid core of the Atacama Desert, Chile, is possibly the driest and most life-limited place on Earth, yet endolithic microorganisms thrive inside halite pinnacles that are part of ancient salt flats. The existence of this microbial community in an environment that excludes any other life forms suggests biological adaptation to high salinity and desiccation stress, and indicates an alternative source of water for life other than rainfall, fog or dew. Here, we show that halite endoliths obtain liquid water through spontaneous capillary condensation at relative humidity (RH) much lower than the deliquescence RH of NaCl. We describe how this condensation could occur inside nano-pores smaller than 100 nm, in a newly characterized halite phase that is intimately associated with the endolithic aggregates. This nano-porous phase helps retain liquid water for long periods of time by preventing its evaporation even in conditions of utmost dryness. Our results explain how life has colonized and adapted to one of the most extreme environments on our planet, expanding the water activity envelope for life on Earth, and broadening the spectrum of possible habitats for life beyond our planet.

  8. Facilitation of endolithic microbial survival in the hyperarid core of the Atacama Desert by mineral deliquescence

    Science.gov (United States)

    Davila, Alfonso F.; Gómez-Silva, Benito; de Los Rios, Asunción; Ascaso, Carmen; Olivares, Hector; McKay, Christopher P.; Wierzchos, Jacek

    2008-03-01

    The hyperarid core of the Atacama Desert is considered the dry limit for life on Earth. Soils in this region have very low abundance of heterotrophic bacteria and are practically barren of photosynthetic microorganisms because of the extreme dry conditions (≤2 mm a-1 rainfall). However, relatively abundant endolithic communities of cyanobacteria (Chroococcidiopsis) occur within halite crusts in paleolake evaporitic deposits. By means of continuous monitoring of the microclimate conditions (temperature, relative humidity, water vapor density, wetness, and photosynthetically active radiation) inside and around the halite crusts, we demonstrate here that water vapor condenses within the pore space of the halite at relative humidity (RH) levels that otherwise hinder the occurrence of liquid water in the surrounding environment. Water condensation occurs at RH >75%, which corresponds to the deliquescence point of halite. We have estimated a total of 57 deliquescence events (i.e., water condensation) within the halite crusts, as opposed to only 1 liquid water event outside. These wet events resulted in a total of 213.8 h of potential photosynthetic activity for the endolithic microorganisms versus only 6 h for organisms outside the halite crusts. Halite crusts may therefore represent the last available niche for photosynthetic activity in extreme arid environments on Earth.

  9. Novel water source for endolithic life in the hyperarid core of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    J. Wierzchos

    2012-06-01

    Full Text Available The hyperarid core of the Atacama Desert, Chile, is possibly the driest and most life-limited place on Earth, yet endolithic microorganisms thrive inside halite pinnacles that are part of ancient salt flats. The existence of this microbial community in an environment that excludes any other life forms suggests biological adaptation to high salinity and desiccation stress, and indicates an alternative source of water for life other than rainfall, fog or dew. Here, we show that halite endoliths obtain liquid water through spontaneous capillary condensation at relative humidity (RH much lower than the deliquescence RH of NaCl. We describe how this condensation could occur inside nano-pores smaller than 100 nm, in a newly characterized halite phase that is intimately associated with the endolithic aggregates. This nano-porous phase helps retain liquid water for long periods of time by preventing its evaporation even in conditions of utmost dryness. Our results explain how life has colonized and adapted to one of the most extreme environments on our planet, expanding the water activity envelope for life on Earth, and broadening the spectrum of possible habitats for life beyond our planet.

  10. Bacterial Diversity within the Extreme Arid Atacama Desert Soils of the Yungay Region, Chile

    Science.gov (United States)

    Connon, S. A.; Lester, E. D.; Shafaat, H. S.; Obenhuber, D. C.; Ponce, A.

    2006-12-01

    Surface and subsurface soil samples analyzed for this study were collected from the hyper-arid Yungay region of the Atacama Desert, Chile. This is the first report of microbial diversity from DNA extracted directly from these extremely desiccated soils. Our data shows that 94% of the 16S rRNA genes cloned from these soils belong to the Actinobacteria phylum. A 24-hour time course series showed a diurnal water activity (aw) cycle that peaked at 0.52 in the early predawn hours, and ranged from 0.08 0.01 during the day. All measured water activity values were below the level required for microbial growth or enzyme activity. Total organic carbon (TOC) levels in this region were just above the limits of detection and ranged from 220 660 μg/g of soil. Phospholipid fatty acid (PLFA) levels indicated cellular biomass ranging from 2 ×105 to 7 ×106 cell equivalents per gram of soil. The culturable counts were low with most samples showing no growth on standard plates of R2A medium; the highest single count was 47 colony forming units (CFU) per gram.

  11. Impact of empire expansion on household diet: the Inka in Northern Chile's Atacama Desert.

    Directory of Open Access Journals (Sweden)

    Sheila Dorsey Vinton

    Full Text Available The impact of expanding civilization on the health of American indigenous societies has long been studied. Most studies have focused on infections and malnutrition that occurred when less complex societies were incorporated into more complex civilizations. The details of dietary change, however, have rarely been explored. Using the analysis of starch residues recovered from coprolites, here we evaluate the dietary adaptations of indigenous farmers in northern Chile's Atacama Desert during the time that the Inka Empire incorporated these communities into their economic system. This system has been described as "complementarity" because it involves interaction and trade in goods produced at different Andean elevations. We find that as local farming societies adapted to this new asymmetric system, a portion of their labor had to be given up to the Inka elite through a corvée tax system for maize production. In return, the Inka system of complementarity introduced previously rare foods from the Andean highlands into local economies. These changes caused a disruption of traditional communities as they instituted a state-level economic system on local farmers. Combined with previously published infection information for the same populations under Inka rule, the data suggest that there may have been a dual health impact from disruption of nutrition and introduction of crowd disease.

  12. Draft Genome Sequence of Hymenobacter sp. Strain AT01-02, Isolated from a Surface Soil Sample in the Atacama Desert, Chile

    DEFF Research Database (Denmark)

    Hansen, Anders Cai Holm; Paulino-Lima, Ivan Glaucio; Fujishima, Kosuke;

    2016-01-01

    Here, we report the 5.09-Mb draft genome sequence of Hymenobacter sp. strain AT01-02, which was isolated from a surface soil sample in the Atacama Desert, Chile. The isolate is extremely resistant to UV-C radiation and is able to accumulate high intracellular levels of Mn/Fe.......Here, we report the 5.09-Mb draft genome sequence of Hymenobacter sp. strain AT01-02, which was isolated from a surface soil sample in the Atacama Desert, Chile. The isolate is extremely resistant to UV-C radiation and is able to accumulate high intracellular levels of Mn/Fe....

  13. Application of artificial neural networks as a tool for moisture prediction in microbially colonized halite in the Atacama Desert

    Science.gov (United States)

    Wierzchos, K.; Cancilla, J. C.; Torrecilla, J. S.; Díaz-Rodríguez, P.; Davila, A. F.; Ascaso, C.; Nienow, J.; McKay, C. P.; Wierzchos, J.

    2015-06-01

    The Atacama Desert is the driest and one of the most life-limiting places on Earth. Despite the extreme conditions, microbial endolithic communities have been found inside halite rocks. The presence of these microbial communities is possible due to the hygroscopic properties of evaporitic rocks composed of sodium chloride. It is important to elucidate every possible water source in such a hyperarid environment. Therefore, in the present study, an artificial neural network (ANN) based model has been designed to predict the presence of liquid water on the surface of halite pinnacles. The model predicts the moisture formation using two basic meteorological variables, air temperature, and air relative humidity. ANNs have been successfully employed for the first time as a tool for predicting the appearance of liquid water, a key factor for the endolithic microbial communities living in the driest part of the Atacama Desert. The model developed is able to correctly predict the formation of water on the surface of the halite pinnacles 83% of the cases. We anticipate the future application of this model as an important tool for the prediction of the water availability and therefore potential habitability of lithic substrates in extreme environments on Earth and perhaps elsewhere.

  14. Investigation into mummies from the Atacama Desert, Chile: Did they suffer from arsenic poisoning?

    Energy Technology Data Exchange (ETDEWEB)

    Krupp, Eva M.; Leidich, Patrick; Raab, Andrea; Ouypornkochagorn, Sairoong; Feldmann, Joerg, E-mail: e.krupp@abdn.ac.uk [TESLA, University of Aberdeen, Aberdeen, Scotland (United Kingdom); Kemp, Helen; Meier-Augenstein, Wolfram [Stable Isotope Laboratory, James Hutton Institute, Invergowrie, Dundee (United Kingdom); Stegen, Susana; Quirolo, Fabrizio; Hubbe, Mark [Universidad del Norte, Antofagasta (Chile)

    2011-07-01

    Full text: the foothills of the Andes. Despite its hostility, people have lived here for thousands of years, manifested by the discovery of mummies which are from Pre-Columbian times and can be as old as 1500 years. In addition, the water of the few oasis and rivers of this region can be highly contaminated by arsenic, which originates from geogenic sources. The work presented here aims on the question whether the people that lived in this region were exposed to arsenic in their drinking water. Arsenic is known for its acute toxicity when administered in high doses, but also its carcinogenic impact even in very low doses, and the WHO standard for maximum As concentration in drinking water was recently reduced to 10 {mu}g/L. Arsenic exposure in people can be monitored in keratogenous material like hair, nails and skin. In addition, arsenic speciation in these tissues can be used to determine whether the As was metabolised in the body, enabling the differentiation from ingestion of As versus external contamination by either As present in the soil or any cosmetic/preservative treatment of the body prior or after death. The Atacama people traditionally buried their dead in shallow graves in the high regions of the altiplano, and the dry and cold climate set on a natural mummification, which leads to the fact that a huge amount of well preserved mummified remains can be found in the desert. Here, we investigate hair, skin and fingernail samples of up to 10 Mummies dated to approx. 500 years of age, for arsenic concentration and speciation of As, focusing on the determination whether these people may have suffered from As exposure through drinking water. Water sources around the find spots of the mummies were investigated for As concentration, and significant variations can be found for different water sources. In addition to arsenic speciation analysis using XANES and HPLC-ICPMS, stable isotope analysis was performed for C,N,O and H, revealing the source of food these

  15. Investigation into mummies from the Atacama Desert, Chile: Did they suffer from arsenic poisoning?

    International Nuclear Information System (INIS)

    Full text: the foothills of the Andes. Despite its hostility, people have lived here for thousands of years, manifested by the discovery of mummies which are from Pre-Columbian times and can be as old as 1500 years. In addition, the water of the few oasis and rivers of this region can be highly contaminated by arsenic, which originates from geogenic sources. The work presented here aims on the question whether the people that lived in this region were exposed to arsenic in their drinking water. Arsenic is known for its acute toxicity when administered in high doses, but also its carcinogenic impact even in very low doses, and the WHO standard for maximum As concentration in drinking water was recently reduced to 10 μg/L. Arsenic exposure in people can be monitored in keratogenous material like hair, nails and skin. In addition, arsenic speciation in these tissues can be used to determine whether the As was metabolised in the body, enabling the differentiation from ingestion of As versus external contamination by either As present in the soil or any cosmetic/preservative treatment of the body prior or after death. The Atacama people traditionally buried their dead in shallow graves in the high regions of the altiplano, and the dry and cold climate set on a natural mummification, which leads to the fact that a huge amount of well preserved mummified remains can be found in the desert. Here, we investigate hair, skin and fingernail samples of up to 10 Mummies dated to approx. 500 years of age, for arsenic concentration and speciation of As, focusing on the determination whether these people may have suffered from As exposure through drinking water. Water sources around the find spots of the mummies were investigated for As concentration, and significant variations can be found for different water sources. In addition to arsenic speciation analysis using XANES and HPLC-ICPMS, stable isotope analysis was performed for C,N,O and H, revealing the source of food these

  16. Shoreline dating of the former Quillagua-Llamara Lake, N-Chile - Implications of global teleconnections to the hydrology of the Atacama Desert

    Science.gov (United States)

    Ritter, Benedikt; Dunai, Tibor; Stuart, Finlay; Wennrich, Volker; Melles, Martin

    2016-04-01

    Cosmogenic nuclide exposure dating of ancient lake-level shoreline terraces of the Quillagua-Llamara Lake in the central Atacama Desert (N-Chile) provides new insights in the paleohydrology of the driest desert on earth. The lake developed from a paleo-exohereic drainage system in the Central Depression, before it opened towards the Pacific and an endohereic drainage system became established due to incision by the Rio Loa. The duration of the lake stages was long enough to cut erosive shoreline terraces into exposed islands. These shoreline features are preserved due to 250 m uplift of islands (Cerro Soledad, Cerro Mogote). Exposure dating of the shorelines reveals the existence of pluvial lake stages in the Atacama Desert during parts of the Late Pliocene and several Pleistocene interglacials (MIS 7, 9, 11, possibly 31, 87-93). These interglacials at least partly coincide with episodes of strong sea-ice retreat or even collapse of the West Antarctic Ice Sheet. This correlation is traced back to dramatic changes in the oceanographic and atmospheric circulation system in the Equatorial-SE Pacific with implications for global climate. A strong reduction in West Antarctic sea ice, followed by a weakening of the Peru-Chile Current and reduced supply of cold water, may have enabled expansion of the Pacific Warm Pool and thus increased sea-surface temperatures along the west coast of South America. These long-lasting, El Niño-like conditions may have in turn decreased the temperature inversion and enabled moisture transport towards the western Andean flanks. Our findings are compatible with evidence from the ANDRILL 1B record from the Ross Sea, Antarctica, and warm-water faunal assemblages on marine shoreline terraces from northern Chile. Furthermore, the exposure ages of the pluvial lake stages narrow the maximum incision age the of Rio Loa canyon and break through the Coastal Cordillera, and imply rock uplift rates of isolated islands in the Central Depression in the

  17. Aqueducts and geoglyphs : the response of Ancient Nasca to water shortages in the desert of Atacama (Peru)

    Science.gov (United States)

    Masini, Nicola; Lasaponara, Rosa

    2016-04-01

    The desert of Atacama is a plateau in South America, covering a 1,000-kilometre strip of land on the Pacific coast, west of the Andes mountains, between Chile and Peru. Due to the confluence of a cold ocean current (the Humboldt Current) along with other climatic factors, connected to the particular topography and geomorphology of the region, Atacama desert is one of the most arid areas of the world. In particular, in Nasca region (Southern Peru) the lack of water was (and still is) due to the following causes: (i) the scarce pluvial precipitations and the (ii) high infiltration capacity, and the consequent yearly significant reduction of the surface water (Schreiber & Lancho Rojas 2009). Over the millennia long periods of drought occurred and frequently the lack of water was persistent for several decades. Despite the arid and extreme nature of the environment, this region was populated by important civilizations, such as Paracas and Nasca, which flourished in the Early Intermediate period (200 BCE-500 AD) (Silvermann & Proulx 2002). In particular the Nasca civilization is well-known for its refined and colourful pottery, characterized by a rich icononographic repertory, and, above all, by the huge and mysterious geoglyphs drawn on the arid plateaus of the Rio Grande de Nasca Basin. In order to practice agriculture, the Nasca developed adequate strategies to cope with hostile environmental factors and water scarcity, building a very efficient aqueduct system. They were aided by the fact that underground water was likely enough close to the surface and accessible by constructing wells and underground aqueducts, known with quechua name of puquios (Schreiber & Lancho Rojas 2009; Lasaponara & Masini 2012a; 2012b) The effectiveness of the techniques of hydraulic engineering depended on the climate and the weather events that sometimes underwent drastic changes, as results of the cyclical phenomenon of El Niño Southern Oscillation (commonly called ENSO). Hence the

  18. 50 years of water extraction in the Pampa del Tamarugal basin: Can Prosopis tamarugo trees survive in the hyper-arid Atacama Desert (Northern Chile)?

    NARCIS (Netherlands)

    Chávez Oyanadel, R.O.; Clevers, J.G.P.W.; Decuyper, M.; Bruin, de S.; Herold, M.

    2016-01-01

    Groundwater-dependent ecosystems are threatened worldwide by unsustainable groundwater (GW) extraction. This is the case of the Prosopis tamarugo Phil forest in the hyper-arid Atacama Desert (Northern Chile), one of the most extreme ecosystems on Earth. Despite concerns about the conservation of thi

  19. Eroding and Inflating the Atacama Desert, Chile: Insights Through Cosmogenic 10-Be, 26-Al and 21-Ne

    Science.gov (United States)

    Heimsath, A. M.; Jungers, M. C.; Amundson, R.; Balco, G.; Shuster, D. L.

    2010-12-01

    Enigmas of the Atacama Desert are as abundant as the hypotheses formulated to explain them. This fascinating and extreme landscape attracts scientists from disparate disciplines, spawning remarkable insights into the connections between climate, tectonics, biota and landscape evolution. Recent work explores such connections on timescales ranging from millions to thousands of years. Both the timing of the onset of hyperaridity in the Atacama and its relationship to the uplift of the Andes are especially well-debated topics. Similarly enigmatic, but less widely studied, are the connections between the timing of hyperaridity and the surface morphology of the region. Specifically, the extent, nature, and timing of formation for the extensive salars across the Atacama are undeniably linked to the climate history of the region. Adjacent to the extensive salars are landscapes that appear to be shaped by processes more typically associated with temperate landscapes: rilling and gullying, extensive terrace deposition, steep fault scarps, landslide deposits, and extensive fan and paleosurface deposits. Our primary goal in this project is to establish chronologies and rates for the surface processes driving landscape evolution for two field regions in the Atacama. To achieve this goal we are also testing and expanding upon the burial dating methodology (Balco and Shuster, 2009) that couples the stable cosmogenic nuclide, 21Ne, with the radiogenic nuclides, 10Be and 26Al. Here we present new results from remarkably different field settings from the north-central Atacama. The southern region, inland from Antofagasta, is relatively well studied to determine how the onset of hyperaridity impacted water-driven processes. The northern region, north of the Rio Loa and Calama, differs most notably by the enormous basin fills of salt (e.g. Salar de Llamara and Salar Grande) and evidence of more extensive recently active salars. Across both regions we use in 10Be, 26Al, and 21Ne to

  20. 800,000-Year Record of Plate Boundary Earthquakes in the Atacama Desert, Northern Chile

    Science.gov (United States)

    Baker, A. M.; Owen, L. A.; Rech, J.; Allmendinger, R. W.

    2010-12-01

    Coseismic cracks preserved in the hyper-arid Atacama Desert of Northern Chile provide a unique record of the seismic history of the modern Andean forearc, which has generated the largest earthquakes on earth. Loveless et al. (2009) mapped more than 50,000 cracks on satellite imagery and, based on boundary element modeling, suggested that they indicate repeated rupture of approximately the same segment. But, what is the time frame of the repeated rupture and what is the long-term strain rate of the forearc due to this process? West of Salar Grande, five overlapping fan surfaces contain different densities of coseismic cracks, allowing for such an assessment. The fan surfaces are highly indurated with gypsum and salt, resulting in excellent preservation of these brittle features. All surfaces are underlain by a tuff ~4 m.y. old. Older surfaces consistently have more and larger cracks than younger surfaces. Locally, cracks cutting across multiple surfaces have distinctly different widths and morphologies. Density is the number of cracks present per given length and total opening is the sum of the widths along that same length. Both crack density and total opening on each surface show a positive relationship to relative age, supporting the previously anecdotal evidence for reactivation of cracks through time with multiple events. Fresh, centimeter-scale cracks are also present on all surfaces, further supporting that these features record a history rather than a singular event. Three of the five fan surfaces have sufficiently large quartz clasts for exposure dating using 10Be and 26Al, providing absolute ages to use in calculating strain rate due to cracking. The oldest surface is 800±100 ky old. Samples from active channels constrain inheritance of cosmogenic nuclides, and nuclide ratios suggest no significant burial. Strain rates calculated from total opening and surface age range from 1.3x10^-15s^-1 to 2.4x10^-15s^-1 across the three surfaces. For comparison, we

  1. Genetic Characterization of Old Grapevines collected in Oases of the Atacama Desert Caracterización Genética de Vides Antiguas colectadas en Oasis del Desierto de Atacama

    OpenAIRE

    Ingrid Poblete; Manuel Pinto; María Teresa de Andrés; Patricio Hinrichsen

    2011-01-01

    Old grapevine (Vitis vinifera L.) accessions are a source of genes that could be rescued for use per se or in modern breeding programs. The first step in this rescuing is collecting and characterizing the germplasm from a particular region. This study presents the genetic characterization of 21 grapevine accessions collected from the Atacama Desert in the far North of Chile. Characterization was based on 12 microsatellites (Simple Sequence Repeats, or SSRs) supplemented with Amplified Fragmen...

  2. Timing of wet episodes in Atacama Desert over the last 15 ka. The Groundwater Discharge Deposits (GWD) from Domeyko Range at 25°S.

    Science.gov (United States)

    Sáez, Alberto; Godfrey, Linda V.; Herrera, Christian; Chong, Guillermo; Pueyo, Juan J.

    2016-08-01

    A chronologically robust reconstruction of timing and dynamics of millennial time scale wet episodes encompassing the entire Atacama Desert during the last 15 ka has been constructed. To accomplish this, a new composite paleoclimatic record from Groundwater Discharge Deposits (GWD) in the Sierra de Varas (Domeyko Range, southern Atacama in Chile at 25°S) has been compiled and compared with other published paleohydrologic records from the Atacama region. In Sierra de Varas (SV), three millennial timescale wet climate phases have been characterized: around 14.5 ka cal BP, 12.2-9.8 ka cal BP, and 4.7 ka cal BP to the present day. These wet phases are interpreted from intervals of GWD facies formed during periods when the springs were active. GWD facies include: (1) black organic peat, rooted mudstones and sandstones formed in local wetland environments, and (2) gypsum-carbonate rich layers formed by interstitial growth. GWD intervals alternate with gravelly alluvial material deposited during arid phases. A trend towards less humid conditions during the Late Holocene wet episode characterizes GWD sedimentary series in Sierra the Varas, suggesting the onset of a dry episode over the last few centuries. Around 0.7 ka BP a very short wet episode is recorded in the central part of the desert suggesting this was the time of maximum humidity for the entire late Holocene wet period. A brief arid phase occurred between 1.5 and 2.0 ka BP indicated by the absence of GWD in the Domeyko Range. The paleoclimatic reconstruction encompassing the entire Atacama region shows that both the intensity and occurrence of wetter conditions were governed mainly by the distance to the source of moisture, and secondarily by the elevation of the sites. In the northern Atacama (16-20°S), four wet phases fed by N-NE summer monsoon precipitations have been proposed: Tauca phase (18-14 ka cal BP) and Coipasa phase (13-10 ka cal BP) during the Late Glacial, followed by Early Holocene and Late

  3. Adaptation strategies of endolithic chlorophototrophs to survive the hyperarid and extreme solar radiation environment of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    Jacek eWierzchos

    2015-09-01

    Full Text Available The Atacama Desert, northern Chile, is one of the driest deserts on Earth and, as such, a natural laboratory to explore the limits of life and the strategies evolved by microorganisms to adapt to extreme environments. Here we report the exceptional adaptation strategies of chlorophototrophic and eukaryotic algae, and chlorophototrophic and prokaryotic cyanobacteria to the hyperarid and extremely high solar radiation conditions occurring in this desert. Our approach combined several microscopy techniques, spectroscopic analytical methods, and molecular analyses. We found that the major adaptation strategy was to avoid the extreme environmental conditions by colonizing cryptoendolithic, as well as, hypoendolithic habitats within gypsum deposits. The cryptoendolithic colonization occurred a few millimeters beneath the gypsum surface and showed a succession of organized horizons of algae and cyanobacteria, which has never been reported for endolithic microbial communities. The presence of cyanobacteria beneath the algal layer, in close contact with sepiolite inclusions, and their hypoendolithic colonization suggest that occasional liquid water might persist within these sub-microhabitats. We also identified the presence of abundant carotenoids in the upper cryptoendolithic algal habitat and scytonemin in the cyanobacteria hypoendolithic habitat. This study illustrates that successful lithobiontic microbial colonization at the limit for microbial life is the result of a combination of adaptive strategies to avoid excess solar irradiance and extreme evapotranspiration rates, taking advantage of the complex structural and mineralogical characteristics of gypsum deposits – conceptually called rock’s habitable architecture. Additionally self-protection by synthesis and accumulation of secondary metabolites likely produces a shielding effect that prevents photoinhibition and lethal photooxidative damage to the chlorophototrophs, representing another

  4. Adaptation strategies of endolithic chlorophototrophs to survive the hyperarid and extreme solar radiation environment of the Atacama Desert

    Science.gov (United States)

    Wierzchos, Jacek; DiRuggiero, Jocelyne; Vítek, Petr; Artieda, Octavio; Souza-Egipsy, Virginia; Škaloud, Pavel; Tisza, Michel; Davila, Alfonso F.; Vílchez, Carlos; Garbayo, Inés; Ascaso, Carmen

    2015-01-01

    The Atacama Desert, northern Chile, is one of the driest deserts on Earth and, as such, a natural laboratory to explore the limits of life and the strategies evolved by microorganisms to adapt to extreme environments. Here we report the exceptional adaptation strategies of chlorophototrophic and eukaryotic algae, and chlorophototrophic and prokaryotic cyanobacteria to the hyperarid and extremely high solar radiation conditions occurring in this desert. Our approach combined several microscopy techniques, spectroscopic analytical methods, and molecular analyses. We found that the major adaptation strategy was to avoid the extreme environmental conditions by colonizing cryptoendolithic, as well as, hypoendolithic habitats within gypsum deposits. The cryptoendolithic colonization occurred a few millimeters beneath the gypsum surface and showed a succession of organized horizons of algae and cyanobacteria, which has never been reported for endolithic microbial communities. The presence of cyanobacteria beneath the algal layer, in close contact with sepiolite inclusions, and their hypoendolithic colonization suggest that occasional liquid water might persist within these sub-microhabitats. We also identified the presence of abundant carotenoids in the upper cryptoendolithic algal habitat and scytonemin in the cyanobacteria hypoendolithic habitat. This study illustrates that successful lithobiontic microbial colonization at the limit for microbial life is the result of a combination of adaptive strategies to avoid excess solar irradiance and extreme evapotranspiration rates, taking advantage of the complex structural and mineralogical characteristics of gypsum deposits—conceptually called “rock's habitable architecture.” Additionally, self-protection by synthesis and accumulation of secondary metabolites likely produces a shielding effect that prevents photoinhibition and lethal photooxidative damage to the chlorophototrophs, representing another level of

  5. UV-resistant yeasts isolated from a high-altitude volcanic area on the Atacama Desert as eukaryotic models for astrobiology

    OpenAIRE

    Pulschen, André A; Rodrigues, Fabio; Duarte, Rubens T D; Araujo, Gabriel G; Santiago, Iara F; Paulino-Lima, Ivan G.; Carlos A Rosa; Massuo J. Kato; Pellizari, Vivian H.; Galante, Douglas

    2015-01-01

    The Sairecabur volcano (5971 m), in the Atacama Desert, is a high-altitude extreme environment with high daily temperature variations, acidic soils, intense UV radiation, and low availability of water. Four different species of yeasts were isolated from this region using oligotrophic media, identified and characterized for their tolerance to extreme conditions. rRNA sequencing revealed high identity (>98%) to Cryptococcus friedmannii, Exophiala sp., Holtermanniella watticus, and Rhodosporidiu...

  6. Hydrogeochemistry and stable isotopes of ground and surface waters from two adjacent closed basins, Atacama Desert, northern Chile

    Science.gov (United States)

    Alpers, C.N.; Whittemore, D.O.

    1990-01-01

    The geochemistry and stable isotopes of groundwaters, surface waters, and precipitation indicate different sources of some dissolved constituents, but a common source of recharge and other constituents in two adjacent closed basins in the Atacama Desert region of northern Chile (24??15???-24??45???S). Waters from artesian wells, trenches, and ephemeral streams in the Punta Negra Basin are characterized by concentrations of Na>Ca>Mg and Cl ???SO4, with TDS Mg ??? Ca and SO4 > Cl, with TDS also Mg ??? Ca and SO4 > Cl, but with TDS up to 40 g/l. The deep mine waters have pH between 3.2 and 3.9, and are high in dissolved CO2 (??13 C = -4.8%PDB), indicating probable interaction with oxidizing sulfides. The deep mine waters have ??18O values of ???-1.8%.compared with values isotopes at elevated temperatures. Alternatively, the deep mine waters may represent fossil meteoric waters which evolved isotopically along an evaporative trend starting from values quite depleted in ??18O and ??Dd relative to either precipitation or shallow groundwaters. High I/Br ratios in the Hamburgo Basin waters and La Escondida mine waters are consistent with regionally high I in surficial deposits in the Atacama Desert region and may represent dissolution of a wind-blown evaporite component. Rain and snow collected during June 1984, indicate systematic ??18O and ??D fractionation with increasing elevation between 3150 and 4180 m a.s.l. (-0.21??.??18O and -1.7??.??D per 100 m). Excluding the deep mine waters from La Escondida, the waters from the Hamburgo and Punta Negra Basins have similar ??D and ??18O values and together show a distinct evaporative trend (??D = 5.0 ??18O - 20.2). Snowmelt from the central Andes Cordillera to the east is the most likely source of recharge to both basins. Some of the waters in the Hamburgo Basin may have been recharged during late Pleistocene, when the climate was wetter and a lake filled the intervening Punta Negra Basin, as suggested by recent archaeological

  7. Urinary arsenic speciation profile in ethnic group of the Atacama desert (Chile) exposed to variable arsenic levels in drinking water.

    Science.gov (United States)

    Yáñez, Jorge; Mansilla, Héctor D; Santander, I Paola; Fierro, Vladimir; Cornejo, Lorena; Barnes, Ramón M; Amarasiriwardena, Dulasiri

    2015-01-01

    Ethnic groups from the Atacama Desert (known as Atacameños) have been exposed to natural arsenic pollution for over 5000 years. This work presents an integral study that characterizes arsenic species in water used for human consumption. It also describes the metabolism and arsenic elimination through urine in a chronically exposed population in northern Chile. In this region, water contained total arsenic concentrations up to 1250 μg L(-1), which was almost exclusively As(V). It is also important that this water was ingested directly from natural water sources without any treatment. The ingested arsenic was extensively methylated. In urine 93% of the arsenic was found as methylated arsenic species, such as monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)]. The original ingested inorganic species [As(V)], represent less than 1% of the total urinary arsenic. Methylation activity among individuals can be assessed by measuring primary [inorganic As/methylated As] and secondary methylation [MMA/DMA] indexes. Both methylation indexes were 0.06, indicating a high biological converting capability of As(V) into MMA and then MMA into DMA, compared with the control population and other arsenic exposed populations previously reported.

  8. Butterflies of the high altitude Atacama Desert: habitat use and conservation

    OpenAIRE

    Emma eDespland

    2014-01-01

    The butterfly fauna of the high-altitude desert of Northern Chile, though depauperate, shows high endemism, is poorly known and is of considerable conservation concern. This study surveys butterflies along the Andean slope between 2400 and 500 m asl (prepuna, puna and Andean steppe habitats) as well as in high and low altitude wetlands and in the neoriparian vegetation of agricultural sites. We also include historical sightings from museum records. We compare abundances between altitudes, be...

  9. Raman imaging in geomicrobiology: endolithic phototrophic microorganisms in gypsum from the extreme sun irradiation area in the Atacama Desert.

    Science.gov (United States)

    Vítek, Petr; Ascaso, Carmen; Artieda, Octavio; Wierzchos, Jacek

    2016-06-01

    The Raman imaging method was successfully applied for mapping the distribution of biomolecules (e.g., pigments) associated with cryptoendolithic and hypoendolithic microorganisms, as well as the inorganic host mineral matrix that forms the habitat for the biota. To the best of our knowledge, this is the first comprehensive study in the field of geomicrobiology based on this technique. The studied microbial ecosystem was located nearly 3000 m above sea level within the driest desert on Earth, the Atacama in Chile. Enhancement of carotenoid Raman signal intensity close to the surface was registered at different areas of endolithic colonization dominated by algae, with cyanobacteria present as well. This is interpreted as an adaptation mechanism to the excessive solar irradiation. On the other hand, cyanobacteria synthesize scytonemin as a passive UV-screening pigment (found at both the hypoendolithic and cryptoendolithic positions). The distribution of the scytonemin Raman signal was mapped simultaneously with the surrounding mineral matrix. Thus, mapping was done of the phototrophic microorganisms in their original microhabitat together with the host rock environment. Important information which was resolved from the Raman imaging dataset of the host rock is about the hydration state of Ca-sulfate, demonstrated on the presence of gypsum (CaSO4·2H2O) and the absence of both anhydrite (CaSO4) and bassanite (CaSO4·1/2H2O). Obtaining combined "in situ" simultaneous information from the geological matrix (inorganic) together with the microbial biomolecules (organic) is discussed and concluded as an important advantage of this technique. We discuss how selection of the laser wavelength (785 and 514.5-nm) influences the Raman imaging results. PMID:27055886

  10. Spatial and temporal constraints on regional-scale groundwater flow in the Pampa del Tamarugal Basin, Atacama Desert, Chile

    Science.gov (United States)

    Jayne, Richard S.; Pollyea, Ryan M.; Dodd, Justin P.; Olson, Elizabeth J.; Swanson, Susan K.

    2016-08-01

    Aquifers within the Pampa del Tamarugal Basin (Atacama Desert, northern Chile) are the sole source of water for the coastal city of Iquique and the economically important mining industry. Despite this, the regional groundwater system remains poorly understood. Although it is widely accepted that aquifer recharge originates as precipitation in the Altiplano and Andean Cordillera to the east, there remains debate on whether recharge is driven primarily by near-surface groundwater flow in response to periodic flood events or by basal groundwater flux through deep-seated basin fractures. In addressing this debate, the present study quantifies spatial and temporal variability in regional-scale groundwater flow paths at 20.5°S latitude by combining a two-dimensional model of groundwater and heat flow with field observations and δ18O isotope values in surface water and groundwater. Results suggest that both previously proposed aquifer recharge mechanisms are likely influencing aquifers within the Pampa del Tamarugal Basin; however, each mechanism is operating on different spatial and temporal scales. Storm-driven flood events in the Altiplano readily transmit groundwater to the eastern Pampa del Tamarugal Basin through near-surface groundwater flow on short time scales, e.g., 100-101 years, but these effects are likely isolated to aquifers in the eastern third of the basin. In addition, this study illustrates a physical mechanism for groundwater originating in the eastern highlands to recharge aquifers and salars in the western Pampa del Tamarugal Basin over timescales of 104-105 years.

  11. Evidence for the development of the Andean rain shadow from a Neogene isotopic record in the Atacama Desert, Chile

    Science.gov (United States)

    Rech, Jason A.; Currie, Brian S.; Shullenberger, Eric D.; Dunagan, Stan P.; Jordan, Teresa E.; Blanco, Nicolás; Tomlinson, Andrew J.; Rowe, Harry D.; Houston, John

    2010-04-01

    Varying ages from Triassic to Pliocene have been proposed for the onset of hyperaridity in the Atacama Desert. The exact timing for the initiation of hyperaridity is critical for determining potential causes, which range from regional effects of global cooling to Andean uplift above elevations conducive to extreme rain shadows. Analysis of the stable isotopic composition of lower Miocene-Quaternary (21-0.015 Ma) palustrine and lacustrine carbonates in the Calama Basin reveals extreme changes in their oxygen and carbon isotopic composition during the Miocene. Limestone δ18O values increased by ˜ 5‰ from middle to late Miocene, ranging from - 5.5‰ at 12 Ma to - 1‰ at ˜ 6 Ma. Carbon isotopic values increase by 9‰ over the Neogene, from average values of - 3‰ at 21 Ma to + 3‰ at 12 Ma, and reaching a maximum of + 6‰ at 5 Ma. The increase in oxygen isotopic values occurred over a time span in which the catchment area of the basin experienced significant uplift, causing the δ18O value of precipitation to become more negative. We attribute the shift towards higher δ18O values to enhanced evaporative enrichment both of soil water or snow prior to infiltration, and within shallow lakes or wetlands prior to carbonate precipitation. The large increase in δ13C values was likely caused by a transition from a vegetated landscape influenced primarily by soil-respired CO 2 to a landscape largely devoid of vegetation and influenced by atmospheric and volcanic CO 2. Isotopic values of palustrine carbonates therefore indicate that hyperaridity commenced in the Calama Basin during the middle to late Miocene, in agreement with other paleoclimatic records from the basin. The cause for the onset of this climate change is thought to be due to the development of a strong Andean rain shadow associated with the uplift of the Andes to mean elevations > 2 km.

  12. Cloud optical depth from total and UV solar irradiance measurements at two sites of the Atacama Desert in Chile

    Science.gov (United States)

    Luccini, Eduardo; Rivas, Miguel; Rojas, Elisa

    2016-06-01

    The visible cloud optical depth (COD) for overcast stratocumulus was estimated at Arica (18.47°S, 70.31°W, 20 m above sea level (asl)) and Poconchile (18.45°S, 70.07°W, 560 m asl), northernmost Chilean sites distant about 30 km in the Atacama Desert, during morning hours for days in which cloudiness dissipates giving cloudless afternoons, from 10 min averaged measurements of total shortwave solar irradiance (ToSI) and ultraviolet solar irradiance (UVSI) during the period 2002-2005. One-dimensional radiative transfer model calculations were made to establish a theoretical relationship between the visible COD, the cloud effective transmittance in both ToSI (CETTo) and UVSI (CETUV), and the solar zenith angle (SZA). It is used to estimate COD from the previously measured CET by Luccini et al. (2011). Measurements in both ToSI and UVSI broadband ranges showed to be reliable to determine the visible COD within this frame. Overcast COD at the coastal site of Arica (typical COD ~ 15) is slightly larger than at the inland site of Poconchile (typical COD ~ 11). Maximum sensitivity of the retrieved CODs was found to variations in the cloud droplet effective radius, surface albedo and aerosol optical depth in both ranges, and in the total ozone column additionally in UVSI. The obtained CODs are linearly related but are higher compared with those from two other parametric methods using the same data. A simple rational expression of CET as a function of COD enables to estimate a mean (spectral and regional) surface albedo in each range that is in turn applicable to fit appropriately the ratio CETTo/CETUV. Instantaneous overpass MODIS-Terra satellite COD at 660 nm show a good agreement with simultaneous (within ± 5 min) ground-derived COD at both sites.

  13. Butterflies of the high altitude Atacama Desert: habitat use and conservation

    Directory of Open Access Journals (Sweden)

    Emma eDespland

    2014-09-01

    Full Text Available The butterfly fauna of the high-altitude desert of Northern Chile, though depauperate, shows high endemism, is poorly known and is of considerable conservation concern. This study surveys butterflies along the Andean slope between 2400 and 500 m asl (prepuna, puna and Andean steppe habitats as well as in high and low altitude wetlands and in the neoriparian vegetation of agricultural sites. We also include historical sightings from museum records. We compare abundances between altitudes, between natural and impacted sites, as well as between two sampling years with different precipitation regimes. The results confirm high altitudinal turnover and show greatest similarity between wetland and slope faunas at similar altitudes. Results also underscore vulnerability to weather fluctuations, particularly in the more arid low-altitude sites, where abundances were much lower in the low precipitation sampling season and several species were not observed at all. Finally, we show that some species have shifted to the neoriparian vegetation of the agricultural landscape, whereas others were only observed in less impacted habitats dominated by native plants. These results suggest that acclimation to novel habitats depends on larval host plant use. The traditional agricultural environment can provide habitat for many, but not all, native butterfly species, but an estimation of the value of these habitats requires better understanding of butterfly life-history strategies and relationships with host plants.

  14. Chroococcidiopsis sp. strain AAB1, a new model from the Atacama desert for the understanding of extreme UV tolerance in an astrobiological context

    International Nuclear Information System (INIS)

    Full text: The Atacama Desert in northern Chile is the driest and oldest desert on Earth. In a recently published report [Azua-Bustos, 2011] we showed that along its Coastal Range, fog can support hypolithic colonization rates of 80From these hypolithic communities we were able to obtain a previously unknown strain of Chroococcidiopsis which we characterized by morphological and molecular means. Due to the extreme tolerance of cyanobacteria of this genus to UV, and since the Atacama Desert has constantly high UV radiation levels all year long, we propose this strain as a pertinent model for understanding the limits UV tolerance for life as we know it. We have measured the viability of the isolate by using the DEAD/LIVE BacLight kit which allows the detection of dead cells by measuring the loss of integrity of the plasma membrane, and found that it remains almost unchanged with control cultures when desiccated. In addition, desiccated samples readily start new cultures. Transmission electron microscopy (TEM) of desiccated samples show no evident changes compared with controls. Pigments extracts from desiccated samples show a decrease in photosynthetic pigments like Chlorophyll-a, measured by fluorescence spectra and by tissue layer chromatography. Desiccated samples also synthesize sucrose, an intracellular compatible solute known to play a role in desiccation tolerance. As desiccation and extreme UV tolerance are thought to share similar metabolic routes [Rebecchi, 2007], we expect that our isolate (as suggested by preliminary experiments performed with our strain at LNLS in 2010) should be extremely tolerant to UV radiation. Future work include exposition of monolayers of our strain using the VUV line, and the determination of its comparative tolerance levels with a Chroococcidiopsis strain (N76) isolated from the Mojave Desert which we also have in culture. The experiments will consist of different exposition times in order to achieve increasing UV accumulation

  15. Chroococcidiopsis sp. strain AAB1, a new model from the Atacama desert for the understanding of extreme UV tolerance in an astrobiological context

    Energy Technology Data Exchange (ETDEWEB)

    Azua-Bustos, A.; Arenas, C. [Pontificia Universidad Catolica de Chile, Santiago (Chile); Paulino-Lima, I G. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil); Galante, D. [Universidade de Sao Paulo (USP), SP (Brazil)

    2012-07-01

    Full text: The Atacama Desert in northern Chile is the driest and oldest desert on Earth. In a recently published report [Azua-Bustos, 2011] we showed that along its Coastal Range, fog can support hypolithic colonization rates of 80From these hypolithic communities we were able to obtain a previously unknown strain of Chroococcidiopsis which we characterized by morphological and molecular means. Due to the extreme tolerance of cyanobacteria of this genus to UV, and since the Atacama Desert has constantly high UV radiation levels all year long, we propose this strain as a pertinent model for understanding the limits UV tolerance for life as we know it. We have measured the viability of the isolate by using the DEAD/LIVE BacLight kit which allows the detection of dead cells by measuring the loss of integrity of the plasma membrane, and found that it remains almost unchanged with control cultures when desiccated. In addition, desiccated samples readily start new cultures. Transmission electron microscopy (TEM) of desiccated samples show no evident changes compared with controls. Pigments extracts from desiccated samples show a decrease in photosynthetic pigments like Chlorophyll-a, measured by fluorescence spectra and by tissue layer chromatography. Desiccated samples also synthesize sucrose, an intracellular compatible solute known to play a role in desiccation tolerance. As desiccation and extreme UV tolerance are thought to share similar metabolic routes [Rebecchi, 2007], we expect that our isolate (as suggested by preliminary experiments performed with our strain at LNLS in 2010) should be extremely tolerant to UV radiation. Future work include exposition of monolayers of our strain using the VUV line, and the determination of its comparative tolerance levels with a Chroococcidiopsis strain (N76) isolated from the Mojave Desert which we also have in culture. The experiments will consist of different exposition times in order to achieve increasing UV accumulation

  16. The potential of Tillandsia dune ecosystems for revealing past and present variations in advective fog along the coastal Atacama Desert, northern Chile

    Science.gov (United States)

    Latorre Hidalgo, C.; García, J. L.; Gonzalez, A. L.; Marquet, P. A.

    2015-12-01

    The coastal Atacama Desert is home to a complex geo-ecosystem supported by fog with multiple atmospheric and oceanic drivers. Fog collectors in place for the last 17 years reveal that monthly fog intensity and amount are significantly linked to the El Niño-Southern Oscillation (ENSO 1+2) with cold (warm) anomalies correlated to increased (decreased) fog (R2 = 0.41). Rainfall, however, can occur during extreme positive ENSO anomalies. Tillandsia landbeckii is an epiarenitic plant common to the coastal Atacama where fog is intercepted by the coastal escarpment between 950-1250 m.a.s.l. These plants possess multiple adaptations to survive exclusively on fog, including the construction of "dune" ecosystems known as "tillandsiales". Buried T. landbeckii layers in such dunes contain a record of past variations of fog over time (dunes can top 3 m in height) and alternating plant and sand layers are readily visible in dune stratigraphy. Stable N isotopes on modern plants and fog indicate that these plants reflect δ15N values of total N dissolved in fog. We measured δ15N values from buried T. landbeckii layers from five different tillandsiales found across c. 50 km the coastal escarpment. The isotope values in these buried plants indicate a prominent c. 8.0 ‰ shift towards more negative δ15N values on average over the last 3,200 years. Based on differences in δ15N between modern and more extensive "paleo" tillandsiales at one of our lowest elevation study sites, we interpret this shift as an increase in available moisture due to increased fog input during the late Holocene. Increased variability in ENSO as well as increased upwelling and southerly winds along the coastal Atacama would explain in part this increase. Clearly, the Atacama tillandsiales have considerable potential for monitoring past and present change of these large-scale ocean-atmosphere systems.

  17. Egg laying site selection by a host plant specialist leaf miner moth at two intra-plant levels in the northern Chilean Atacama Desert

    Directory of Open Access Journals (Sweden)

    José Storey-Palma

    2014-09-01

    Full Text Available Egg laying site selection by a host plant specialist leaf miner moth at two intra-plant levels in the northern Chilean Atacama Desert. The spatial distribution of the immature stages of the leaf miner Angelabella tecomae Vargas & Parra, 2005 was determined at two intra-plant levels (shoot and leaflet on the shrub Tecoma fulva fulva (Cav. D. Don (Bignoniaceae in the Azapa valley, northern Chilean Atacama Desert. An aggregated spatial pattern was detected for all the immature stages along the shoot, with an age dependent relative position: eggs and first instar larvae were clumped at apex; second, third and fourth instar larvae were mostly found at intermediate positions; meanwhile the spinning larva and pupa were clumped at basis. This pattern suggests that the females select new, actively growing leaflets for egg laying. At the leaflet level, the immature stages were found more frequently at underside. Furthermore, survivorship was higher for larvae from underside mines. All these results highlight the importance of an accurate selection of egg laying site in the life history of this highly specialized leaf miner. By contrast, eventual wrong choices in the egg laying site selection may be associated with diminished larval survivorship. The importance of the continuous availability of new plant tissue in this highly human modified arid environment is discussed in relation with the observed patterns.

  18. Microbial colonization of Ca-sulfate crusts in the hyperarid core of the Atacama Desert: implications for the search for life on Mars.

    Science.gov (United States)

    Wierzchos, J; Cámara, B; de Los Ríos, A; Davila, A F; Sánchez Almazo, I M; Artieda, O; Wierzchos, K; Gómez-Silva, B; McKay, C; Ascaso, C

    2011-01-01

    The scarcity of liquid water in the hyperarid core of the Atacama Desert makes this region one of the most challenging environments for life on Earth. The low numbers of microbial cells in the soils suggest that within the Atacama Desert lies the dry limit for life on our planet. Here, we show that the Ca-sulfate crusts of this hyperarid core are the habitats of lithobiontic micro-organisms. This microporous, translucent substrate is colonized by epilithic lichens, as well as endolithic free-living algae, fungal hyphae, cyanobacteria and non photosynthetic bacteria. We also report a novel type of endolithic community, "hypoendoliths", colonizing the undermost layer of the crusts. The colonization of gypsum crusts within the hyperarid core appears to be controlled by the moisture regime. Our data shows that the threshold for colonization is crossed within the dry core, with abundant colonization in gypsum crusts at one study site, while crusts at a drier site are virtually devoid of life. We show that the cumulative time in 1 year of relative humidity (RH) above 60% is the best parameter to explain the difference in colonization between both sites. This is supported by controlled humidity experiments, where we show that colonies of endolithic cyanobacteria in the Ca-sulfate crust undergo imbibition process at RH >60%. Assuming that life once arose on Mars, it is conceivable that Martian micro-organisms sought refuge in similar isolated evaporite microenvironments during their last struggle for life as their planet turned arid. PMID:20726901

  19. UV-resistant yeasts isolated from a high-altitude volcanic area on the Atacama Desert as eukaryotic models for astrobiology.

    Science.gov (United States)

    Pulschen, André A; Rodrigues, Fabio; Duarte, Rubens T D; Araujo, Gabriel G; Santiago, Iara F; Paulino-Lima, Ivan G; Rosa, Carlos A; Kato, Massuo J; Pellizari, Vivian H; Galante, Douglas

    2015-08-01

    The Sairecabur volcano (5971 m), in the Atacama Desert, is a high-altitude extreme environment with high daily temperature variations, acidic soils, intense UV radiation, and low availability of water. Four different species of yeasts were isolated from this region using oligotrophic media, identified and characterized for their tolerance to extreme conditions. rRNA sequencing revealed high identity (>98%) to Cryptococcus friedmannii, Exophiala sp., Holtermanniella watticus, and Rhodosporidium toruloides. To our knowledge, this is the first report of these yeasts in the Atacama Desert. All isolates showed high resistance to UV-C, UV-B and environmental-UV radiation, capacity to grow at moderate saline media (0.75-2.25 mol/L NaCl) and at moderate to cold temperatures, being C. friedmannii and H. watticus able to grow in temperatures down to -6.5°C. The presence of pigments, analyzed by Raman spectroscopy, correlated with UV resistance in some cases, but there is evidence that, on the natural environment, other molecular mechanisms may be as important as pigmentation, which has implications for the search of spectroscopic biosignatures on planetary surfaces. Due to the extreme tolerances of the isolated yeasts, these organisms represent interesting eukaryotic models for astrobiological purposes.

  20. Microbial colonization of Ca-sulfate crusts in the hyperarid core of the Atacama Desert: implications for the search for life on Mars.

    Science.gov (United States)

    Wierzchos, J; Cámara, B; de Los Ríos, A; Davila, A F; Sánchez Almazo, I M; Artieda, O; Wierzchos, K; Gómez-Silva, B; McKay, C; Ascaso, C

    2011-01-01

    The scarcity of liquid water in the hyperarid core of the Atacama Desert makes this region one of the most challenging environments for life on Earth. The low numbers of microbial cells in the soils suggest that within the Atacama Desert lies the dry limit for life on our planet. Here, we show that the Ca-sulfate crusts of this hyperarid core are the habitats of lithobiontic micro-organisms. This microporous, translucent substrate is colonized by epilithic lichens, as well as endolithic free-living algae, fungal hyphae, cyanobacteria and non photosynthetic bacteria. We also report a novel type of endolithic community, "hypoendoliths", colonizing the undermost layer of the crusts. The colonization of gypsum crusts within the hyperarid core appears to be controlled by the moisture regime. Our data shows that the threshold for colonization is crossed within the dry core, with abundant colonization in gypsum crusts at one study site, while crusts at a drier site are virtually devoid of life. We show that the cumulative time in 1 year of relative humidity (RH) above 60% is the best parameter to explain the difference in colonization between both sites. This is supported by controlled humidity experiments, where we show that colonies of endolithic cyanobacteria in the Ca-sulfate crust undergo imbibition process at RH >60%. Assuming that life once arose on Mars, it is conceivable that Martian micro-organisms sought refuge in similar isolated evaporite microenvironments during their last struggle for life as their planet turned arid.

  1. Phytostabilization of arsenic in soils with plants of the genus Atriplex established in situ in the Atacama Desert.

    Science.gov (United States)

    Fernández, Yasna Tapia; Diaz, O; Acuña, E; Casanova, M; Salazar, O; Masaguer, A

    2016-04-01

    In the ChiuChiu village (Atacama Desert, Chile), there is a high concentration of arsenic (As) in the soil due to natural causes related to the presence of volcanoes and geothermal activity. To compare the levels of As and the growth parameters among plants of the same genus, three species of plants were established in situ: Atriplex atacamensis (native of Chile), Atriplex halimus, and Atriplex nummularia. These soils have an As concentration of 131.2 ± 10.4 mg kg(-1), a pH of 8.6 ± 0.1, and an electrical conductivity of 7.06 ± 2.37 dS m(-1). Cuttings of Atriplex were transplanted and maintained for 5 months with periodic irrigation and without the addition of fertilizers. The sequential extraction of As indicated that the metalloid in these soils has a high bioavailability (38 %), which is attributed to the alkaline pH, low organic matter and Fe oxide content, and sandy texture. At day 90 of the assay, the As concentrations in the leaves of A. halimus (4.53 ± 1.14 mg kg(-1)) and A. nummularia (3.85 ± 0.64 mg kg(-1)) were significantly higher than that in A. atacamensis (2.46 ± 1.82 mg kg(-1)). However, the three species accumulated higher levels of As in their roots, indicating a phytostabilization capacity. At the end of the assay, A. halimus and A. nummularia generated 30 % more biomass than A. atacamensis without significant differences in the As levels in the leaves. Despite the difficult conditions in these soils, the establishment of plants of the genus Atriplex is a recommended strategy to generate a vegetative cover that prevents the metalloid from spreading in this arid area through the soil or by wind.

  2. Multiple Sulfate Isotopic Evidence on the Formation of Oxide Copper Ore at Spence, Atacama Desert, Northern Chile

    Science.gov (United States)

    Sun, T.; Bao, H.; Reich, M.; Palacios, C.

    2007-12-01

    In the Atacama Desert of northern Chile, one of the world's richest metallogenic provinces, porphyry copper deposits are characterized by the unique occurrence of atacamite in their oxidized zones. The origin and formation of the oxide zone of these copper deposits is, however, controversial. It was proposed that Cl-rich deep formation water pumping-up events along faults by earthquakes, after onset of the hyperaridity, were required (Cameron et al., 2007). Their model would imply that supplies of saline deep formation water from fractures to the surface should have left behind a homogeneous or fracture-controlled salt profile from surface down to the oxide zone. While no excluding the deep formation water model in other deposit, here we propose that, in our sampling region, the alternative saline source, which is critical for atacamite formation, could be locally evaporated groundwater, Cl-rich salts leached from arid surface by meteoric water, or brines from eastern salar basins at a time when the climate in northern Chile was changing from arid to hyperarid. At this climate transition, arid- requiring minerals such as atacamite in the oxide zone were formed and, more importantly, preserved upon evaporation beneath the surface alluvial deposits. Since salt accumulation at the surface remain active during hyperarid condition, our model would predict that water-soluble salt profile from surface to the oxide zone should have a characteristic pattern: salts with an atmospheric component on the surface gradually transitioning to salts of the oxide ore zone on the bottom and a mixing zone in between. To test these two alternative models, we focus on sulfate salts, one of the common water-soluble salts in arid environments. An added advantage is that sulfate accumulated on desert surface has a secondary atmospheric component that bears a unique triple oxygen isotope signature, easily distinguishable from sulfate formed by the oxidation of sulfide minerals at the oxide

  3. Paleosol-based evidence for humid to semi-arid pre-10Ma climates in the Atacama Desert, Chile

    Science.gov (United States)

    Oerter, E.; Amundson, R.; Heimsath, A. M.; Jungers, M. C.; Chong, G.

    2011-12-01

    The Tertiary paleoclimate of the Atacama Desert is poorly known and widely debated. Post-10 Ma climate has at least one early period of hyperaridity (Resh et al., 2006, Geology, 34:761), and multiple lines of evidences for a strong and nearly-continuous post-Pliocene hyper-aridification largely coincident with changes in Pacific sea surface temperatures (Amundson et al., in press). In 2010, we examined a sequence of pre-10 Ma gravelly, continental sediments exposed at the El Tesoro Mine, near Calama Chile. The gravel underlies a 10 Ma ignimbrite, and the geomorphic surfaces above this layer consist of largely incised fluvial surfaces of Miocene (?) to recent age. Several tuff samples from nearby the mine have been identified and are being processed for 40Ar/39Ar geochronological analyses. Here, we focus on the ~300 m sequence of gravels we examined that contained a sequence of 22 or more paleosols (22° 57' S, 69° 5' W). The paleosols were developed on an aggrading alluvial fan system from streams largely to the east, and lie above the mineralized gravels that host the copper ore body. The soils are extremely well preserved due to minimal burial and little aqueous diagenesis. The remarkable feature of the paleosols is that they represent oscillating soil forming conditions between chemical weathering/clay production (humid: Alfisols) to environments that facilitated the accumulation of pedogenic carbonate (arid to semi-arid: Aridisols). All carbonate bearing samples are being analyzed for stable C and O isotopes. All bulk samples are being analyzed for total geochemical composition, to yield an examination of chemical alteration. Samples from the two oldest paleosols in the sequence (Calcids or Calciarids) average δ13C and δ18O values (VPDB) of ca. -3.1 and -4.2 respectively. Presently, the local region is a sulfate-, rather than carbonate-, forming soil environment. At elevations exceeding ~2500 m, carbonates begin to appear. Based on analyses of nearby sites

  4. Modestobacter caceresii sp. nov., novel actinobacteria with an insight into their adaptive mechanisms for survival in extreme hyper-arid Atacama Desert soils.

    Science.gov (United States)

    Busarakam, Kanungnid; Bull, Alan T; Trujillo, Martha E; Riesco, Raul; Sangal, Vartul; van Wezel, Gilles P; Goodfellow, Michael

    2016-06-01

    A polyphasic study was designed to determine the taxonomic provenance of three Modestobacter strains isolated from an extreme hyper-arid Atacama Desert soil. The strains, isolates KNN 45-1a, KNN 45-2b(T) and KNN 45-3b, were shown to have chemotaxonomic and morphological properties in line with their classification in the genus Modestobacter. The isolates had identical 16S rRNA gene sequences and formed a branch in the Modestobacter gene tree that was most closely related to the type strain of Modestobacter marinus (99.6% similarity). All three isolates were distinguished readily from Modestobacter type strains by a broad range of phenotypic properties, by qualitative and quantitative differences in fatty acid profiles and by BOX fingerprint patterns. The whole genome sequence of isolate KNN 45-2b(T) showed 89.3% average nucleotide identity, 90.1% (SD: 10.97%) average amino acid identity and a digital DNA-DNA hybridization value of 42.4±3.1 against the genome sequence of M. marinus DSM 45201(T), values consistent with its assignment to a separate species. On the basis of all of these data, it is proposed that the isolates be assigned to the genus Modestobacter as Modestobacter caceresii sp. nov. with isolate KNN 45-2b(T) (CECT 9023(T)=DSM 101691(T)) as the type strain. Analysis of the whole-genome sequence of M. caceresii KNN 45-2b(T), with 4683 open reading frames and a genome size of ∽4.96Mb, revealed the presence of genes and gene-clusters that encode for properties relevant to its adaptability to harsh environmental conditions prevalent in extreme hyper arid Atacama Desert soils. PMID:27108251

  5. Ignimbrite as a substrate for endolithic life in the hyper-arid Atacama Desert: Implications for the search for life on Mars

    Science.gov (United States)

    Wierzchos, Jacek; Davila, Alfonso F.; Artieda, Octavio; Cámara-Gallego, Beatriz; de los Ríos, Asunción; Nealson, Kenneth H.; Valea, Sergio; Teresa García-González, M.; Ascaso, Carmen

    2013-06-01

    The hyper-arid core of the Atacama Desert in Chile is considered the driest and most life-limited place on Earth, with few habitats capable of sustaining an active microbial ecosystem. As such, it is one of the best terrestrial analogues of the extreme arid conditions on Mars, and an ideal environment to explore survival and biological adaptation strategies as the environment becomes increasingly dry. Here we show that weakly welded rhyolitic ignimbrites in this desert are abundantly colonized by endolithic cyanobacteria and associated heterotrophic bacteria. We propose that the porous ignimbrite interior provides protection from damaging UV radiation and excessive levels of visible light. Rock porosity also favors cell hydration through water retention after scarce rainfall events, even when the surrounding environment remains stubbornly dry. This is the first known example of an endolithic microbial community colonizing ignimbrite rocks in an extremely dry environment. The existence of a habitat capable of supporting abundant phototrophic and heterotrophic communities in an environment that precludes most life forms suggests that, if similar deposits are found on Mars, these should be considered important targets in the search for life. Indeed, ignimbrite rocks have been tentatively identified in Gale Crater, the landing site of the Mars Science Laboratory (MSL) mission and could be directly analyzed by its rover Curiosity.

  6. Multi-annual climate in Parque Nacional Pan de Azúcar, Atacama Desert, Chile Clima multianual en el Parque Nacional Pan de Azúcar, Desierto de Atacama, Chile

    Directory of Open Access Journals (Sweden)

    MATTHEW V. THOMPSON

    2003-06-01

    Full Text Available The lomas formations of the Peruvian and Atacama deserts are characterized by both climatic and floristic spatial heterogeneity, as well as non-contiguous pockets of relatively distinct flora. We examined two distinct types of communities in Parque Nacional Pan de Azúcar in Chile, the low-elevation arroyo and bajada community, and the high-elevation fog-zone community. We determined the distribution with elevation of the dominant perennial plant species in a single arroyo community, as well as the distribution of associated climatic characteristics. Climatic conditions (including air temperature, relative humidity, and wind speed and direction were recorded from June, 1999, to March, 2001, for the arroyo, as well as for a medium-elevation inland site with little vegetation, and a high-elevation fog-zone site with copious vegetation. The fog layer, or camanchaca, derived from the marine inversion layer ubiquitous to the Peruvian and Atacama deserts was found to be more persistent, though weaker, during the summer months and somewhat more condensed and shallower in the winter months, with uncharacteristically dry air and high temperatures occurring at and above 400 m elevation during the late fall and early winter of 2000. The reduction or increase in the maximum elevation of the camanchaca or a change in the rainfall regime of the park may have broad implications for the distribution or even presence of certain species in Parque Nacional Pan de Azúcar. Vegetation patterns appear to be strongly dependent on inversion layer development, and perhaps on its subsidence during the winter. A number of species prevalent at low-elevation sites may have little advantage at a high-elevation foggy site, whereas the consistently high humidity at low elevations would be a boon to any desert plant accustomed to low precipitation. If we are to successfully assess the effects of changes in southern Pacific weather patterns, it will become necessary to more

  7. Genetic Characterization of Old Grapevines collected in Oases of the Atacama Desert Caracterización Genética de Vides Antiguas colectadas en Oasis del Desierto de Atacama

    Directory of Open Access Journals (Sweden)

    Ingrid Poblete

    2011-09-01

    Full Text Available Old grapevine (Vitis vinifera L. accessions are a source of genes that could be rescued for use per se or in modern breeding programs. The first step in this rescuing is collecting and characterizing the germplasm from a particular region. This study presents the genetic characterization of 21 grapevine accessions collected from the Atacama Desert in the far North of Chile. Characterization was based on 12 microsatellites (Simple Sequence Repeats, or SSRs supplemented with Amplified Fragment Length Polymorphic (AFLP markers. Most of the collected accessions produced red berries and shared the genetic characteristics of the cv. País, an old genotype found throughout America. However, among those red-berried accessions, one showed a severe abortive phenotype (22S7, and another (6S4 differed from ‘País’ in one allele. Both could be examples of somatic mutations, even though no variations in their AFLP patterns were found. On the other hand, the only accession with red berries that exhibited genetic characteristics different from those of ‘País’ (5CN corresponded to ‘Gros Colman’, a supposedly Georgian genotype introduced to this region by the mid-20th century. Greater genetic diversity was detected among the white and pink accessions, which were classified into five clades based on their SSR allelic patterns. Of these genotypes, 11Si was identified as ‘Emperatriz’ or ‘Red Seedless’, an Argentinean variety; accessions 16H1 and 17H2 corresponded to a product of crossing ‘País’ and ‘Muscat of Alexandria’; and, finally, accession 20S5 was identified as ‘Ahmeur bou Ahmeur’, an Algerian genotype harboring pink berries. Two seeded genotypes harboring small and large white berries were not identified as known varieties. The possible use of these accessions for breeding to enhance survival in the harsh environment of the Atacama Desert is discussed.Las accesiones de vid (Vitis vinifera L. de antigua data son una fuente de

  8. Bioremediation of contaminated mixtures of desert mining soil and sawdust with fuel oil by aerated in-vessel composting in the Atacama Region (Chile)

    International Nuclear Information System (INIS)

    Since early 1900s, with the beginning of mining operations and especially in the last decade, small, although repetitive spills of fuel oil had occurred frequently in the Chilean mining desert industry during reparation and maintenance of machinery, as well as casual accidents. Normally, soils and sawdust had been used as cheap readily available sorbent materials of spills of fuel oil, consisting of complex mixtures of aliphatic and aromatic hydrocarbons. Chilean legislation considers these fuel oil contaminated mixtures of soil and sawdust as hazardous wastes, and thus they must be contained. It remains unknown whether it would be feasible to clean-up Chilean desert soils with high salinity and metal content, historically polluted with different commercial fuel oil, and contained during years. Thus, this study evaluated the feasibility of aerated in-vessel composting at a laboratory scale as a bioremediation technology to clean-up contaminated desert mining soils (fuel concentration > 50,000 mg kg-1) and sawdust (fuel concentration > 225,000 mg kg-1) in the Atacama Region. The composting reactors were operated using five soil to sawdust ratios (S:SD, 1:0, 3:1, 1:1, 1:3, 0:1, on a dry weight basis) under mesophilic temperatures (30-40 deg. C), constant moisture content (MC, 50%) and continuous aeration (16 l min-1) during 56 days. Fuel oil concentration and physico-chemical changes in the composting reactors were monitored following standard procedures. The highest (59%) and the lowest (35%) contaminant removals were observed in the contaminated sawdust and contaminated soil reactors after 56 days of treatment, respectively. The S:SD ratio, time of treatment and interaction between both factors had a significant effect (p < 0.050) on the contaminant removal. The results of this research indicate that bioremediation of an aged contaminated mixture of desert mining soil and sawdust with fuel oil is feasible. This study recommends a S:SD ratio 1:3 and a correct

  9. Assessing water stress of desert vegetation using remote sensing : the case of the Tamarugo forest in the Atacama Desert (Northern Chile)

    NARCIS (Netherlands)

    Chávez Oyanadel, R.O.

    2014-01-01

    Water stress assessment of natural vegetation plays a key role in water management of desert ecosystems. It allows scientists and managers to relate water extraction rates to changes in vegetation water condition, and consequently to define safe water extraction rates for maintaining a healthy ecosy

  10. Antifungal activity of extracts from Atacama Desert fungi against Paracoccidioides brasiliensis and identification of Aspergillus felis as a promising source of natural bioactive compounds.

    Science.gov (United States)

    Mendes, Graziele; Gonçalves, Vívian N; Souza-Fagundes, Elaine M; Kohlhoff, Markus; Rosa, Carlos A; Zani, Carlos L; Cota, Betania B; Rosa, Luiz H; Johann, Susana

    2016-03-01

    Fungi of the genus Paracoccidioides are responsible for paracoccidioidomycosis. The occurrence of drug toxicity and relapse in this disease justify the development of new antifungal agents. Compounds extracted from fungal extract have showing antifungal activity. Extracts of 78 fungi isolated from rocks of the Atacama Desert were tested in a microdilution assay against Paracoccidioides brasiliensis Pb18. Approximately 18% (5) of the extracts showed minimum inhibitory concentration (MIC) values ≤ 125.0 µg/mL. Among these, extract from the fungus UFMGCB 8030 demonstrated the best results, with an MIC of 15.6 µg/mL. This isolate was identified as Aspergillus felis (by macro and micromorphologies, and internal transcribed spacer, β-tubulin, and ribosomal polymerase II gene analyses) and was grown in five different culture media and extracted with various solvents to optimise its antifungal activity. Potato dextrose agar culture and dichloromethane extraction resulted in an MIC of 1.9 µg/mL against P. brasiliensis and did not show cytotoxicity at the concentrations tested in normal mammalian cell (Vero). This extract was subjected to bioassay-guided fractionation using analytical C18RP-high-performance liquid chromatography (HPLC) and an antifungal assay using P. brasiliensis. Analysis of the active fractions by HPLC-high resolution mass spectrometry allowed us to identify the antifungal agents present in the A. felis extracts cytochalasins. These results reveal the potential of A. felis as a producer of bioactive compounds with antifungal activity. PMID:27008375

  11. The miniaturized Raman system and detection of traces of life in halite from the Atacama Desert: some considerations for the search for life signatures on Mars.

    Science.gov (United States)

    Vítek, Petr; Jehlička, Jan; Edwards, Howell G M; Hutchinson, Ian; Ascaso, Carmen; Wierzchos, Jacek

    2012-12-01

    Raman spectroscopy is being adopted as a nondestructive instrumentation for the robotic exploration of Mars to search for traces of life in the geological record. Here, miniaturized Raman spectrometers of two different types equipped with 532 and 785 nm lasers for excitation, respectively, were compared for the detection of microbial biomarkers in natural halite from the hyperarid region of the Atacama Desert. Measurements were performed directly on the rock as well as on the homogenized, powdered samples prepared from this material-the effects of this sample preparation and the excitation wavelength employed in the analysis are compared and discussed. From these results, 532 nm excitation was found to be superior for the analysis of powdered specimens due to its high sensitivity toward carotenoids and hence a higher capability for their detection at relatively low concentration in bulk powdered specimens. For the same reason, this wavelength was a better choice for the detection of carotenoids in direct measurements made on the rock samples. The 785 nm excitation wavelength, in contrast, proved to be more sensitive toward the detection of scytonemin.

  12. Oxalate formation under the hyperarid conditions of the Atacama desert as a mineral marker to provide clues to the source of organic carbon on Mars

    Science.gov (United States)

    Cheng, Z. Y.; Fernández-Remolar, D. C.; Izawa, M. R. M.; Applin, D. M.; Chong Díaz, M.; Fernandez-Sampedro, M. T.; García-Villadangos, M.; Huang, T.; Xiao, L.; Parro, V.

    2016-06-01

    In this study, we report the detection and characterization of the organic minerals weddellite (CaC2O4 · 2H2O) and whewellite (CaC2O4 · H2O) in the hyperarid, Mars-like conditions of the Salar Grande, Atacama desert, Chile. Weddellite and whewellite are commonly of biological origin on Earth and have great potential for preserving records of carbon geochemistry and possible biological activity on Mars if they are present there. Weddellite and whewellite have been found as secondary minerals occurring inside the lower detrital unit that fills the Salar Grande basin. The extremely low solubility of most oxalate minerals inhibits detection of oxalate by ion chromatography (IC). Crystalline oxalates, including weddellite and whewellite, were detected by X-ray diffraction (XRD). The association of weddellite with surface biota and its presence among subsurface detrital materials suggest the potential of a biological origin for Salar Grande weddellite and whewellite. In this regard, biological activity is uniquely capable of concentrating oxalates at levels detectable by XRD. The complementary detection of oxalate-bearing phases through IC in the upper halite-rich unit suggests the presence of a soluble oxalate phase in the basin that is not detected by XRD. The formation, transport, and concentration of oxalate in the Salar Grande may provide a geochemical analogue for oxalate-bearing minerals recently suggested to exist on Mars.

  13. Assessing water stress of desert vegetation using remote sensing : the case of the Tamarugo forest in the Atacama Desert (Northern Chile)

    OpenAIRE

    Chávez Oyanadel, R.O.

    2014-01-01

    Water stress assessment of natural vegetation plays a key role in water management of desert ecosystems. It allows scientists and managers to relate water extraction rates to changes in vegetation water condition, and consequently to define safe water extraction rates for maintaining a healthy ecosystem. Previous research has shown that optical remote sensing constitutes a powerful tool for assessing vegetation water stress due to its capability of quantitatively estimating important paramete...

  14. Combining numerical modeling and stable isotope values to quantify groundwater recharge from the Chilean Andes to the Pampa del Tamarugal Basin, Atacama Desert, northern Chile

    Science.gov (United States)

    Dodd, J. P.; Pollyea, R.

    2014-12-01

    The Atacama Desert of northern Chile is one of the driest regions on Earth and receives less than 5mm of precipitation annually. The Pampa del Tamarugal (PdT) Basin contains the largest aquifer system in the region, yet the mechanisms and timing of aquifer recharge and continental-scale groundwater flux are poorly understood. Although there is little debate that the source of groundwater recharge is the higher elevation regions of the Andean Altiplano to the east of the PdT Basin, there remains much uncertainty surrounding the mechanisms and timing of aquifer recharge and continental-scale groundwater flux. Most recharge models of the PdT focus on surface water runoff and alluvial fan recharge on shorter time scales, but many of these models explicitly neglect deep flow pathways. Previous investigators have combined the thermal aquifer profile and 14C groundwater ages to propose an alternative conceptual model in which cold meteoric water infiltrates deep into the Cordillera before circulating upward into the PdT by thermal convection through fault-controlled migration pathways. Although this conceptual model provides a convincing theoretical argument for deep fluid circulation, it cannot constrain the magnitude of this deep recharge flux. In this work, we revisit deep-flow conceptual model by combining the spatial distribution of hydrogen and oxygen isotope values as groundwater tracers with a non-isothermal model of continental scale groundwater flow through a two-dimensional transect from the Chilean Andes to the PdT Basin. This work provides first-order estimates on the contribution of deep groundwater circulation within the PdT Aquifer, while providing a framework for (1) quantifying boundary conditions for high resolution models of groundwater resources within the PdT Aquifer, (2) assessing the influence of variable future climate scenarios for groundwater availability in the region, and (3) further integrating conservative tracers and numerical models for

  15. Spatial and temporal variation in tree-ring α-cellulose oxygen and hydrogen isotope values as a record of water availability in the Atacama Desert

    Science.gov (United States)

    Olson, E. J.; Dodd, J. P.

    2015-12-01

    Previous studies have documented that tree ring oxygen and hydrogen isotopes primarily reflect source water; however, biosynthetic fractionation processes modify this signal and can have a varied response to environmental conditions. The degree to which source water contributes to δ2H and δ18O values of plant α-cellulose is species-specific and modern calibration studies are necessary. Here we present a calibration data set of P. tamarugo α-cellulose δ2H and δ18O values from the Atacama Desert in Northern Chile. P. tamarugo trees are endemic to the region and have adapted to the extremely arid environment where average annual precipitation is 2 ‰ over the past 20 years associated with a ~1.1 m lowering of the local groundwater table throughout the area. The correlation between a-cellulose isotope values and hydrologic conditions in modern times provides a baseline for interpretation of tree-ring isotope chronologies from the past 9.5 kya. A high-resolution Holocene (1.8-9.1 kya) age record of Prosopis sp. tree ring α-cellulose δ18O values provides a proxy for climatic and hydrologic conditions. During the early Holocene δ18O values range from 31 to 35‰ (2σ=0.58‰), while during the late Holocene values are much more variable (27.4 to 41‰; 2σ=2.64‰). Anthropogenic demand on local water sources is the most significant environmental factor affecting the variation in modern α-cellulose δ18O values; however, climate induced changes in regional water availability are the dominant driver of variability in the paleo-record. Increased variability in α-cellulose δ18O values in the late Holocene most likely indicates a reduction in annual recharge and an increase in episodic flood events driven by ENSO and other modes of atmospheric variability.

  16. Late Cenozoic geomorphologic signal of Andean forearc deformation and tilting associated with the uplift and climate changes of the Southern Atacama Desert (26°S 28°S)

    Science.gov (United States)

    Riquelme, Rodrigo; Hérail, Gérard; Martinod, Joseph; Charrier, Reynaldo; Darrozes, José

    2007-05-01

    We analyze remarkable examples of the large (˜ 10,000 km 2) and local-scale (˜ 100 km 2) landscape forms related to Late Cenozoic geomorphologic evolution of the Andean forearc region in the Southern Atacama Desert. We also consider the continental sedimentary deposits, so-called "Atacama Gravels", which are related to the degradation of the landscape during the Neogene. Our analysis integrates 1:50,000 field cartography, Landsat TM images observations, ˜ 1:1000 sedimentary logging data, and 50 m horizontal resolution topographic data to reconstruct the Late Cenozoic geomorphologic evolution of this region and discuss the factors that control it, i.e., Miocene aridification of the climate and Neogene Central Andean uplift. We determine that the Precordillera was already formed in the Oligocene and most of the present-day altitude of the Precordillera was reached before that time. Afterward, five episodes of geomorphologic evolution can be differentiated: (1) the development of an Oligocene deep incised drainage system cutting the uplifted Precordillera (up to 2000 m of vertical incision) and connecting it to the Ocean; followed by (2) the infilling of deep incised valleys by up to 400 m of Atacama Gravels. This infill started in the Early Miocene with the development of fluvial deposition and finished in the Middle Miocene with playa and playa lake depositions. We propose that playa-related deposition occurs in an endorheic context related to tectonic activity of the Atacama Fault System and Coastal Cordillera uplift. However, the upward sedimentologic variation in the Atacama Gravels evidences a progressive aridification of the climate. Subsequently, we have identified the effects of the Middle-Upper Miocene slow tectonic deformation: the Neogene Andean uplift is accommodated by a tilting or flexuring of the inner-forearc (Central Depression and Precordillera) related to some hundreds of meters of uplift in the Precordillera. This tilting or flexuring results

  17. Variations in groundwater availability during the past 9,000 years in the Atacama Desert, Chile: A subannual record of oxygen isotope values from Prosopis tamarugo tree rings

    Science.gov (United States)

    Dodd, J. P.; Rivera, M.

    2012-12-01

    The Atacama Desert is among the driest regions on Earth; therefore, access to water is critical to human populations throughout the Pampa del Tamarugal region of northern Chile (20° to 22°S, 69° to 70°W). Presently, the region receives Prosopis tamarugo tree rings indicate that the region has become increasingly arid over the past 9ka, likely as a result of decreased water transport from these recharge areas. Oxygen isotope values from α-cellulose of P. tamarugo tree rings from the Llamara Basin (9130 ±145 and 7910 to 7870 ±10 Cal BP), Ramaditas (2615 ±135 Cal BP), and La Tirana Refresco (modern) record sub-annual variations in groundwater availability in the Pampa del Tamarugal. Low δ18O values (23.8 to 32.8‰) in the P. tamarugo samples from the Llamara Basin indicate wetter conditions prior to 7.8 ka; however, sub-annual variability in the δ18O values remains relatively high with an average range in intra-ring values of 3.0‰ (2σ=1.1‰). P. tamarugo logs that were used as building materials and grown in agricultural fields at Ramaditas (~2.6ka), an archeological site in the Pampa del Tamarugal, have a wider range of δ18O values (17.5 to 35.6‰) and greater intra-ring variability (ave. 4.5‰, 2σ=3.2‰). The greater range in interannual and subannual δ18O values most likely reflects a period with highly variable fluxes of runoff/recharge water. The development and eventual abandonment of Ramaditas and other settlements appear to coincide with changes in the availability of water in the region. Modern P. tamarugo from La Tirana Refresco collected in 2008 have δ18O values that are consistently higher (33.1 to 36.3‰) with much lower intra-ring variability (1.5‰, 2σ=0.9‰), indicating persistently drier conditions and greater evaporative effects on the water used by the P. tamarugo trees. These data provide critical information about the effects of water availability on human settlement in the Pampa del Tamarugal and will enhance our

  18. Water relations and foliar isotopic composition of Prosopis tamarugo Phil. an endemic tree of the Atacama Desert growing under three levels of water table depth.

    Directory of Open Access Journals (Sweden)

    Marco eGarrido

    2016-03-01

    Full Text Available Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the Pampa del Tamarugal, Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m and 7.1 ± 0.1 m, (the last GWD being our reference were selected and groups of 4 individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and midday water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ13C and δ18O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behaviour and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P

  19. Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth.

    Science.gov (United States)

    Garrido, Marco; Silva, Paola; Acevedo, Edmundo

    2016-01-01

    Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the "Pampa del Tamarugal", Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ(13)C and δ(18)O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after

  20. Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth

    Science.gov (United States)

    Garrido, Marco; Silva, Paola; Acevedo, Edmundo

    2016-01-01

    Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the “Pampa del Tamarugal”, Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ13C and δ18O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after

  1. Thermal and Evolved Gas Analysis (TEGA) of hyperarid soils doped with microorganisms from the Atacama Desert in southern Peru (Pampas de la Joya): Implications for the Phoenix Mission

    Science.gov (United States)

    Valdivia-Silva, Julio E.; Navarro-Gonzalez, Rafael; McKay, Chris

    less arid soils. Organic C in the form of CO2 (ion 44 m/z) for microorganisms evolved between 326±19.5° C showing characteristic patterns for each one. Others ions such as 41, 78 and 91 m/z were found too. Interestingly, the release of CO2 increased and ions previously found disappeared, demonstrating a high-oxidant activity in the soil matrix when it is subjected to temperature. Samples of soil pre-treated show CO2 evolved up to 650° C suggesting thermal decomposition of carbonates. Finally in hyperarid soils, ion 44 began its release to 330±30° C while the less arid soils to 245±45° C. These results indicate that some organics (mixed with soils) are oxidized to CO2, and that carbonates present in hyperarid soils also decompose into CO2. The nature of oxidant(s) present in the soils from Pampas de La Joya is still unknown. Key words: Thermal analysis, TEGA, Atacama desert, La Joya desert, hyperarid soils.

  2. Beryllium-10 concentrations in the hyper-arid soils in the Atacama Desert, Chile: Implications for arid soil formation rates and El Niño driven changes in Pliocene precipitation

    Science.gov (United States)

    Wang, Fan; Michalski, Greg; Seo, Ji-Hye; Granger, Darryl E.; Lifton, Nathaniel; Caffee, Marc

    2015-07-01

    Meteoric 10Be concentrations in soil were measured to understand the mechanism, timescale, and climatic dependence of soil formation in the hyper-arid Atacama Desert. The observed systematic decline of soil 10Be concentrations with depth has been reproduced using a simple model that assumes soil matrix, including 10Be, builds up as layers over time while 10Be decays in situ. This suggests a mechanism of soil accumulation via atmospheric deposition, which is in agreement with stable isotopic evidence. The model estimates an age of ∼6.6 ± 0.4 Ma for the total soil profile. Small discrepancies between the model and observations are likely mainly due to changes in precipitation rates that can impact 10Be delivery rates and 10Be movement within the profile. Interpreted in this way, the 10Be data suggest drying in the Atacama after ∼4.7 Ma, and returning to an insignificant wet period at ∼1 Ma, which was possibly connected to El Niño- or La Niña-like climate change.

  3. Levels of total arsenic in edible fish and shellfish obtained from two coastal sectors of the Atacama Desert in the north of Chile: use of non-migratory marine species as bioindicators of sea environmental pollution.

    Science.gov (United States)

    Cornejo-Ponce, Lorena; Lienqueo, Hugo H; Arriaza, Bernardo T

    2011-01-01

    The Camarones (CB) and Vitor (VB) Bays are situated in the middle of Atacama Desert, and their economies are based on activities entirely associated with the extraction of marine produce. The aim of this study was to determine the total arsenic content in three species of fish and seven species of shellfish from these two bays. The quantification of the total arsenic content in these products was performed by Hydride-Generation Atomic Absorption Spectrometry, HG-AAS. The results showed that marine species associated with the CB sector had higher total arsenic levels than the same species in the area of VB, a finding attributed to much higher total arsenic concentrations in the water and soils of CB than VB. The species with the highest total arsenic concentration was the Venus antique (7.50 mg kg (-1)) from the CB, and the lowest total arsenic content was found in Cheilodactylidae variegatus (0.34 mg kg(-1)) from VB. PMID:21879860

  4. Neotectonics In The Central Depression (atacama Desert, 25-26°s, Northern Chile) and Its Implications For Recent Sedimentary Fluxes and Regional Deformation

    Science.gov (United States)

    Audin, L.; Hérail, G.; Riquelme, R.; Darrozes, J.; Martinod, J.; Font, E.

    In the northern Chilean Andes, the Pampas Exploradora and Carizo are part of a NS- trending basin (known as the Central Depression) that separates the Coastal Range from the Precodillera. The Exploradora and Carizo region has undergone an extremely arid climate at least since the Middle Miocene time (~15 Ma ago). The limited extent of erosion, due to exceptional aridity, has greatly contributed to the preservation of the landform. In such environment the landforms can be very well used to analyse the tectonic evolution. A basin infilling occurred during the Cenozoic (Atacama Gravels) with the deposition of large volumes of coarse gravels coming from the Precordillera. The aggradation and filling of the paleo-drainage system by the Atacama Gravels of fluviatil origin mark an important erosive unconformity. Moreover, this uniform preserved surface has undergone low magnitude deformation during the deposition period. But we have evidenced a late and post Atacama Gravel tectonic episode. On the western side of the Precordillera a number of normal faults that cross a dense network of very well preserved channels and its alluvial fans. This tectonic deformation is not large in magnitude, about 2m of vertical offset, but clearly appear in the landscape suggesting that the landforms and deformation in the western part of the basin may be quite young. The easterly dipping normal fault set does not correspond with a regional dip toward the west and thus does not satisfy an hypothesis of gravitationnal reajustment or collapse. On the contrary, west of the normal fault set, some ongoing compressional forces are revealed by a large scale folding of the Central basin. These tectonic features led to some minor topographic variations that produced on the top of the basin surface local sedimentary traps, regressive erosion, catchments and extrado grabens that controlled the sediment facies and distribution pattern. Recent coarse-grained alluvial fans were deposited and stopped by

  5. APECS - The Atacama Pathfinder Experiment Control System

    CERN Document Server

    Muders, D; Hafok, H; Hatchell, J; Koenig, C; Polehampton, E; Schaaf, R; Schuller, F; Tak, F; Wyrowski, F

    2006-01-01

    APECS is the distributed control system of the new Atacama Pathfinder EXperiment (APEX) telescope located on the Llano de Chajnantor at an altitude of 5107 m in the Atacama desert in northern Chile. APECS is based on Atacama Large Millimeter Array (ALMA) software and employs a modern, object-oriented design using the Common Object Request Broker Architecture (CORBA) as the middleware. New generic device interfaces simplify adding instruments to the control system. The Python based observer command scripting language allows using many existing software libraries and facilitates creating more complex observing modes. A new self-descriptive raw data format (Multi-Beam FITS or MBFITS) has been defined to store the multi-beam, multi-frequency data. APECS provides an online pipeline for initial calibration, observer feedback and a quick-look display. APECS is being used for regular science observations in local and remote mode since August 2005.

  6. EL IMAGINARIO PEDAGÓGICO EN LAS ESCUELAS SALITRERAS DEL DESIERTO DE ATACAMA

    OpenAIRE

    JOSÉ ANTONIO GONZÁLEZ

    2011-01-01

    RESUMEN El artículo analiza el funcionamiento del sistema escolar durante el ciclo salitrero en el desierto de Atacama, destacando las escuelas, las bibliotecas, el profesorado, el alumnado y las relaciones entre los normalistas y las empresas salitreras. Palabras claves: Escuelas, Oficinas salitreras, Desierto de Atacama, Antofagasta. ABSTRACT This paper analyzes the school system operation during the nitrate mine cycle in the Atacama Desert, pointing out schools, libraries, teachers, studen...

  7. The Atacama Large Millimeter/submillimeter Array

    CERN Document Server

    Wootten, Alwyn

    2009-01-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) is an international radio telescope under construction in the Atacama Desert of northern Chile. ALMA is situated on a dry site at 5000 m elevation, allowing excellent atmospheric transmission over the instrument wavelength range of 0.3 to 10 mm. ALMA will consist of two arrays of high-precision antennas. One, of up to 64 12-m diameter antennas, is reconfigurable in multiple patterns ranging in size from 150 meters up to ~15 km. A second array is comprised of a set of four 12-m and twelve 7-m antennas operating in one of two closely packed configurations ~50 m in diameter. The instrument will provide both interferometric and total-power astronomical information on atomic, molecular and ionized gas and dust in the solar system, our Galaxy, and the nearby to high-redshift universe. In this paper we outline the scientific drivers, technical challenges and planned progress of ALMA.

  8. Climate Change in Deserts and the Role of CO2

    International Nuclear Information System (INIS)

    Impressive climate changes between the glaciers of the Alps and the deserts of the Namib (Namibia), the Atacama (Chile) and the Thar (Pakistan) since the last 500 000 years raise the question whether they have been caused by the up and down of the atmospheric CO2. If so, can the global CO2 policy prevent the inundation of the densely populated coast strips around the world or does it favor the wealth of the rich countries in the middle latitudes penalizing the poor people living in the arid belt. Desert research has answers because these areas react particularly sensitive to climatic changes but suffers from the shortage of material suitable for accurate dating. However, numerical dating is indispensable for a success. The results and consequences of our own research, including also rare but relevant papers of others, will be discussed. (author)

  9. Searching for Life with Rovers: Exploration Methods & Science Results from the 2004 Field Campaign of the "Life in the Atacama" Project and Applications to Future Mars Missions

    Science.gov (United States)

    Cabrol, N. A.a; Wettergreen, D. S.; Whittaker, R.; Grin, E. A.; Moersch, J.; Diaz, G. Chong; Cockell, C.; Coppin, P.; Dohm, J. M.; Fisher, G.

    2005-01-01

    The Life In The Atacama (LITA) project develops and field tests a long-range, solarpowered, automated rover platform (Zo ) and a science payload assembled to search for microbial life in the Atacama desert. Life is barely detectable over most of the driest desert on Earth. Its unique geological, climatic, and biological evolution have created a unique training site for designing and testing exploration strategies and life detection methods for the robotic search for life on Mars.

  10. Expedition Atacama - project AMOS in Chile

    Science.gov (United States)

    Tóth, J.; Kaniansky, S.

    2016-01-01

    The Slovak Video Meteor Network operates since 2009 (Tóth et al., 2011). It currently consists of four semi-automated all-sky video cameras, developed at the Astronomical Observatory in Modra, Comenius University in Bratislava, Slovakia. Two new generations of AMOS (All-sky Meteor Orbit System) cameras operate fully automatically at the Canary Islands, Tenerife and La Palma, since March 2015 (Tóth et al., 2015). As a logical step, we plan to cover the southern hemisphere from Chile. We present observational experiences in meteor astronomy from the Atacama Desert and other astronomical sites in Chile. This summary of the observations lists meteor spectra records (26) between Nov.5-13, 2015 mostly Taurid meteors, single and double station meteors as well as the first light from the permanent AMOS stations in Chile.

  11. Atmospheric origins of perchlorate on Mars and in the Atacama

    Science.gov (United States)

    Catling, D. C.; Claire, M. W.; Zahnle, K. J.; Quinn, R. C.; Clark, B. C.; Hecht, M. H.; Kounaves, S.

    2010-01-01

    Isotopic studies indicate that natural perchlorate is produced on Earth in arid environments by the oxidation of chlorine species through pathways involving ozone or its photochemical products. With this analogy, we propose that the arid environment on Mars may have given rise to perchlorate through the action of atmospheric oxidants. A variety of hypothetical pathways can be proposed including photochemical reactions, electrostatic discharge, and gas-solid reactions. Because perchlorate-rich deposits in the Atacama desert are closest in abundance to perchlorate measured at NASA's Phoenix Lander site, we made a preliminary study of the means to produce Atacama perchlorate to help shed light on the origin of Martian perchlorate. We investigated gas phase pathways using a 1-D photochemical model. We found that perchlorate can be produced in sufficient quantities to explain the abundance of perchlorate in the Atacama from a proposed gas phase oxidation of chlorine volatiles to perchloric acid. The feasibility of gas phase production for the Atacama provides justification for future investigations of gas phase photochemistry as a possible source for Martian perchlorate.

  12. Fast Detection of Phenolic Compounds in Extracts of Easter Pears (Pyrus communis from the Atacama Desert by Ultrahigh-Performance Liquid Chromatography and Mass Spectrometry (UHPLC–Q/Orbitrap/MS/MS

    Directory of Open Access Journals (Sweden)

    Mario J. Simirgiotis

    2016-01-01

    Full Text Available A small Chilean variety of pears growing in the town of Toconao, an oasis located at the northeastern edge of the Salar de Atacama, northern Chile, was studied by means of modern PDA and high resolution mass spectral data (UHPLC-PDA-HESI-orbitrap-MS/MS. In addition, the antioxidant features of the fruits were compared with the varieties Packhman’s Triumph and Abate Fetel and correlated with the presence of phenolic compounds. The non-pigmented phenolics were fingerprinted and related to the antioxidant capacities measured by the bleaching of the DPPH radical, the ferric reducing antioxidant power (FRAP, the superoxide anion scavenging activity assay (SA, and total content of phenolics and flavonoids measured by spectroscopic methods. The machine allowed a fast separation of 15 min employing a flow rate of 1 mL per minute and could accurately identify 25 compounds, including several isorhamnetin derivatives and phenolic acids, present in the peel and pulps of this Chilean variety for the first time. The compounds were monitored using a wavelength range of 210–800 nm. The native small Chilean pear showed the highest antioxidant activity measured as the bleaching of the DPPH radical, the ferric reducing antioxidant power and superoxide anion scavenging activity (8.61 ± 0.65 μg/mL, 712.63 ± 12.12 micromols trolox equivalents (μmol/TE/100 g FW, and 82.89% ± 2.52% at 100 μg/mL, respectively.

  13. Fast Detection of Phenolic Compounds in Extracts of Easter Pears (Pyrus communis) from the Atacama Desert by Ultrahigh-Performance Liquid Chromatography and Mass Spectrometry (UHPLC-Q/Orbitrap/MS/MS).

    Science.gov (United States)

    Simirgiotis, Mario J; Quispe, Cristina; Bórquez, Jorge; Areche, Carlos; Sepúlveda, Beatriz

    2016-01-01

    A small Chilean variety of pears growing in the town of Toconao, an oasis located at the northeastern edge of the Salar de Atacama, northern Chile, was studied by means of modern PDA and high resolution mass spectral data (UHPLC-PDA-HESI-orbitrap-MS/MS). In addition, the antioxidant features of the fruits were compared with the varieties Packhman's Triumph and Abate Fetel and correlated with the presence of phenolic compounds. The non-pigmented phenolics were fingerprinted and related to the antioxidant capacities measured by the bleaching of the DPPH radical, the ferric reducing antioxidant power (FRAP), the superoxide anion scavenging activity assay (SA), and total content of phenolics and flavonoids measured by spectroscopic methods. The machine allowed a fast separation of 15 min employing a flow rate of 1 mL per minute and could accurately identify 25 compounds, including several isorhamnetin derivatives and phenolic acids, present in the peel and pulps of this Chilean variety for the first time. The compounds were monitored using a wavelength range of 210-800 nm. The native small Chilean pear showed the highest antioxidant activity measured as the bleaching of the DPPH radical, the ferric reducing antioxidant power and superoxide anion scavenging activity (8.61 ± 0.65 μg/mL, 712.63 ± 12.12 micromols trolox equivalents (μmol/TE)/100 g FW, and 82.89% ± 2.52% at 100 μg/mL, respectively). PMID:26784158

  14. The Atacama Cosmology Telescope: The Receiver and Instrumentation

    CERN Document Server

    Swetz, D S; Amiri, M; Appel, J W; Battistelli, E S; Burger, B; Chervenak, J; Devlin, M J; Dicker, S R; Doriese, W B; Dünner, R; Essinger-Hileman, T; Fisher, R P; Fowler, J W; Halpern, M; Hasselfield, M; Hilton, G C; Hincks, A D; Irwin, K D; Jarosik, N; Kaul, M; Klein, J; Lau, J M; Limon, M; Marriage, T A; Marsden, D; Martocci, K; Mauskopf, P; Moseley, H; Netterfield, C B; Niemack, M D; Nolta, M R; Page, L A; Parker, L; Staggs, S T; Stryzak, O; Switzer, E R; Thornton, R; Tucker, C; Wollack, E; Zhao, Y

    2010-01-01

    The Atacama Cosmology Telescope was designed to measure small-scale anisotropies in the Cosmic Microwave Background and detect galaxy clusters through the Sunyaev-Zel'dovich effect. The instrument is located on Cerro Toco in the Atacama Desert, at an altitude of 5190 meters. A six-meter off-axis Gregorian telescope feeds a new type of cryogenic receiver, the Millimeter Bolometer Array Camera. The receiver features three 1000-element arrays of transition-edge sensor bolometers for observations at 148 GHz, 218 GHz, and 277 GHz. Each detector array is fed by free space mm-wave optics. Each frequency band has a field of view of approximately 22' x 26'. The telescope was commissioned in 2007 and has completed its third year of operations. We discuss the major components of the telescope, camera, and related systems, and summarize the instrument performance.

  15. The Atacama Cosmology Telescope: The Receiver and Instrumentation

    Science.gov (United States)

    Swetz, D. S.; Ade, P. A. R.; Amiri, M.; Appel, J. W.; Burger, B.; Devlin, M. J.; Dicker, S. R.; Doriese, W. B.; Essinger-Hileman, T.; Fisher, R. P.; Fowler, J. W.; Halpern, M.; Hasselfield, M.; Hilton, G. C.; Hincks, A. D.; Irwin, K. D.; Jarosik, N.; Kaul, M.; Klein, J.; Marsden, D.; Thornton, R.; Mauskopf, P.; Niemack, M. D.; Page, L. A.; Parker, L.

    2010-01-01

    The Atacama Cosmology Telescope was designed to measure small-scale anisotropies in the Cosmic Microwave Background and detect galaxy clusters through the Sunyaev-Zel'dovich effect. The instrument is located on Cerro Taco in the Atacama Desert, at an altitude of 5190 meters. A six-met.er off-axis Gregorian telescope feeds a new type of cryogenic receiver, the Millimeter Bolometer Array Camera. The receiver features three WOO-element arrays of transition-edge sensor bolometers for observations at 148 GHz, 218 GHz, and 277 GHz. Each detector array is fed by free space mm-wave optics. Each frequency band has a field of view of approximately 22' x 26'. The telescope was commissioned in 2007 and has completed its third year of operations. We discuss the major components of the telescope, camera, and related systems, and summarize the instrument performance.

  16. Tibet's Ali: Asia's Atacama?

    CERN Document Server

    Ye, Quan-Zhi; Li, Hong; Zhang, Xinmin

    2015-01-01

    The Ngari (Ali) prefecture of Tibet, one of the highest areas in the world, has recently emerged as a promising site for future astronomical observation. Here we use 31 years of reanalysis data from the Climate Forecast System Reanalysis (CFSR) to examine the astroclimatology of Ngari, using the recently-erected Ali Observatory at Shiquanhe (5~047~m above mean sea level) as the representative site. We find the percentage of photometric night, median atmospheric seeing and median precipitable water vapor (PWV) of the Shiquanhe site to be $57\\%$, $0.8"$ and 2.5~mm, comparable some of the world's best astronomical observatories. Additional calculation supports the Shiquanhe region as one of the better sites for astronomical observations over the Tibetan Plateau. Based on the studies taken at comparable environment at Atacama, extraordinary observing condition may be possible at the few vehicle-accessible 6~000~m heights in the Shiquanhe region. Such possibility should be thoroughly investigated in future.

  17. The Atacama Large Millimeter Array (ALMA)

    Science.gov (United States)

    1999-06-01

    -versions of different quality that require RealPlayer software. There is no audio. Note that ESO Video News Reel No. 5 with more related scenes and in professional format with complete shot list is also available. ESO PR Photo 24b/99 ESO PR Photo 24b/99 [Preview - JPEG: 400 x 446 pix - 184k] [Normal - JPEG: 800 x 892 pix - 588k] [High-Res - JPEG: 3000 x 3345 pix - 5.4M] Caption to ESO PR Photo 24b/99 : View of Northern Chile, as seen from the NASA Space Shuttle during a servicing mission to the Hubble Space Telescope (partly visible to the left). The Atacama Desert, site of the ESO VLT at Paranal Observatory and the proposed location for ALMA at Chajnantor, is seen from North (foreground) to South. The two sites are only a few hundred km distant from each other. Few clouds are seen in this extremely dry area, due to the influence of the cold Humboldt Stream along the Chilean Pacific coast (right) and the high Andes mountains (left) that act as a barrier. Photo courtesy ESA astronaut Claude Nicollier. ESO PR Photo 24c/99 ESO PR Photo 24c/99 [Preview - JPEG: 400 x 318 pix - 212k] [Normal - JPEG: 800 x 635 pix - 700k] [High-Res - JPEG: 3000 x 2382 pix - 5.9M] Caption to ESO PR Photo 24c/99 : This satellite image of the Chajnantor area was produced in 1998 at Cornell University (USA), by Jennifer Yu, Jeremy Darling and Riccardo Giovanelli, using the Thematic Mapper data base maintained at the Geology Department laboratory directed by Bryan Isacks. It is a composite of three exposures in spectral bands at 1.6 µm (rendered as red), 1.0 µm (green) and 0.5 µm (blue). The horizontal resolution of the false-colour image is about 30 meters. North is at the top of the photo. ESO PR Photo 24d/99 ESO PR Photo 24d/99 [Preview - JPEG: 400 x 381 pix - 108k] [Normal - JPEG: 800 x 762 pix - 240k] [High-Res - JPEG: 2300 x 2191 pix - 984k] Caption to ESO PR Photo 24d/99 : Geographical map with the sites of the VLT and ALMA indicated. ESO PR Photo 24e/99 ESO PR Photo 24e/99 [Preview - JPEG: 400

  18. Robotic Technologies for Surveying Habitats and Seeking Evidence of Life: Results from the 2004 Field Experiments of the "Life in the Atacama" Project

    Science.gov (United States)

    Wettergreen, D.; Cabrol, N.; Whittaker, W.; Diaz, G. Chong; Calderon, F.; Heys, S.; Jonak, D.; Lueders, A.; Moersch, J.; Pane, D.

    2005-01-01

    The Chilean Atacama Desert is the most arid region on Earth and in several ways analogous to Mars. Evidence suggests that the interior of the Atacama is lifeless, yet where the desert meets the Pacific coastal range dessication-tolerant microorganisms are known to exist. The gradient of biodiversity and habitats in the Atacama's subregions remain unexplored and are the focus of the Life in the Atacama project. Our field investigation attempts to bring further scientific understanding of the Atacama as a habitat for life through the creation of robotic astrobiology. This involves capabilities for autonomously traversing hundreds of kilometers while deploying sensors to survey the varying geologic and biologic properties of the environment, Fig. 1. Our goal is to make genuine discoveries about the limits of life on Earth and to generate knowledge about life in extreme environments that can be applied to future planetary missions. Through these experiments we also hope to develop and practice the methods by which a rover might best be employed to survey desert terrain in search of the habitats in which life can survive, or may have in the past.

  19. A review of the non-bulimulid terrestrial Mollusca from the Region of Atacama, northern Chile

    Science.gov (United States)

    Araya, Juan Francisco; Catalán, Ricardo

    2014-01-01

    Abstract Terrestrial mollusca are sparsely studied in Chile and, for the first time, a formal record of the diversity of land snails in northern Chile is reported. Coastal and desertic areas in the Region of Atacama, in the border of the Atacama desert and the Pacific Ocean, were surveyed with the aim to describe the presence and distribution of this poorly known fauna. Of the fourteen species recorded, the geographic distribution records for nine species are extended, and some taxa are recorded for the first time since their original descriptions. All, except one, of the fourteen terrestrial molluscan species occurring in the area are endemic to Chile; they are all terrestrial species, most of them have a restricted geographic distribution, and none of them is currently protected by law. The results reveal that the region of Atacama has one of the most diverse terrestrial snail biodiversity in Chile, ranking only after the Juan Fernandez Archipelago. Distribution records of all the studied species and a taxonomic key are also provided. PMID:24715800

  20. Spectroscopic Results from the Life in the Atacama (LITA) Project 2004 Field Season

    Science.gov (United States)

    Piatek, J. L.; Moersch, J. E.; Wyatt, M.; Rampey, M.; Cabrol, N. A.; Wettergreen, D. S.; Whittaker, R.; Grin, E. A.; Diaz, G. Chong

    2005-01-01

    Introduction: The Life in the Atacama (LITA) project includes rover field tests designed to look for life in the arid environment of the Atacama Desert (Chile). Field instruments were chosen to help remote observers identify potential habitats and the presence of life in these habitats, and included two spectrometers for help in identifying the mineralogy of the field sites. Two field trials were undertaken during the 2004 field season. The remote science team had no prior knowledge of the local geology, and relied entirely on orbital images and rover-acquired data to make interpretations. Each field trial lasted approximately one week: the sites for these trials were in different locations, and are designated "Site B" and "Site C."

  1. El Qhapaqñan entre Atacama y Lípez The Qhapaqñan between Atacama and Lípez

    Directory of Open Access Journals (Sweden)

    Axel E. Nielsen

    2006-12-01

    Full Text Available Este trabajo describe tramos de dos ramales del Qhapaqñan que comunican el desierto de Atacama (Región de Antofagasta, Chile con el Altiplano de Lípez (Departamento Potosí, Bolivia. El primero de ellos, que se extiende entre Licancabur y Laguna Chojllas, formaba parte de una vía que vinculaba el nodo inkaico de San Pedro de Atacama con los valles chichas y la Puna argentina. El segundo ingresa a Bolivia por el Portezuelo del Inca procedente de la cuenca del río Salado y se dirige directamente hacia la zona de Chiguana-Colcha K, que parece haber operado como eje del dominio Inka sobre el Altiplano de Lípez. Partiendo de estos datos, se discuten aspectos relacionados con la circulación de bienes, el aprovisionamiento de los contingentes en tránsito y las prácticas rituales asociadas a los pasos montañosos que atraviesa el camino.This paper describes segments of two branches of the Inka road that communicate the Atacama Desert (Antofagasta Region, Chile and the Lípez Altiplano (Department of Potosi, Bolivia. The first, which extends between Licancabur and Laguna Chojllas, was part of a road that connected the Inka node of San Pedro de Atacama with the Chicha Valleys and the Argentine Puna. The second enters Bolivia through Portezuelo del Inca, coming from the Salado River basin, and heads directly toward Chiguana-Colcha K, an area that apparently served as the axis of Inka rule in the Lipez Altiplano. On the basis of these data, we discuss issues related to the circulation of goods, the supply of groups using the tampu system, and the ritual practices associated with the mountain passes along the road.

  2. Detectors for the Atacama B-mode Search experiment

    Science.gov (United States)

    Appel, John William

    Inflation is the leading theory for explaining the initial conditions that brought about our homogeneous and isotropic Universe. It predicts the presence of gravitational waves in the early Universe, which implant a characteristic B-mode polarization pattern on the Cosmic Microwave Background (CMB). The Atacama B-mode Search (ABS) experiment is a polarimeter observing from Cerro Toco (located in the Atacama desert of Chile at an altitude of 5190 m), searching for the yet undetected B-mode signal. ABS carries 480 superconducting Transition Edge Sensor (TES) Bolometers that couple 150 GHz radiation via planar Ortho-Mode Transducers (OMTs) mounted at the output of corrugated feedhorns. The feedhorn beam is projected onto the sky through crossed Dragonian reflectors, a set of reflective and absorptive filters, and a rotating Half Wave Plate (HWP) that modulates any polarized sky signal at 10.2 Hz. The bolometers are cooled to 300 mK by a He3-He4 adsorption fridge system backed by pulse tubes. The reflectors are located within the 4 K cavity of the cryostat, while the HWP is mounted on frictionless air bearings above the cryostat window. This thesis discusses the development and construction of the ABS detector focal plane, and presents results of its performance in the field through August 2012. The ABS detector array sensitivity of 31 μKs 1/2, together with the experiment's unique set of systematic controls, and expected multi-year integration time, could detect a B-mode signal with tensor to scalar ratio r ˜ 0.1.

  3. A Microbial Oasis in the Hypersaline Atacama Subsurface Discovered by a Life Detector Chip: Implications for the Search for Life on Mars

    OpenAIRE

    Parro, Victor; de Diego-Castilla, Graciela; Moreno-Paz, Mercedes; Blanco, Yolanda; Cruz-Gil, Patricia; Rodríguez-Manfredi, José A.; Fernández-Remolar, David; Gómez, Felipe; Manuel J. Gómez; Luis A Rivas; Demergasso, Cecilia; Echeverría, Alex; Urtuvia, Viviana N.; Ruiz-Bermejo, Marta; García-Villadangos, Miriam

    2011-01-01

    The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5 m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery o...

  4. Desert Pathfinder at Work

    Science.gov (United States)

    2005-09-01

    The Atacama Pathfinder Experiment (APEX) project celebrates the inauguration of its outstanding 12-m telescope, located on the 5100m high Chajnantor plateau in the Atacama Desert (Chile). The APEX telescope, designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range, passed successfully its Science Verification phase in July, and since then is performing regular science observations. This new front-line facility provides access to the "Cold Universe" with unprecedented sensitivity and image quality. After months of careful efforts to set up the telescope to work at the best possible technical level, those involved in the project are looking with satisfaction at the fruit of their labour: APEX is not only fully operational, it has already provided important scientific results. "The superb sensitivity of our detectors together with the excellence of the site allow fantastic observations that would not be possible with any other telescope in the world," said Karl Menten, Director of the group for Millimeter and Sub-Millimeter Astronomy at the Max-Planck-Institute for Radio Astronomy (MPIfR) and Principal Investigator of the APEX project. ESO PR Photo 30/05 ESO PR Photo 30/05 Sub-Millimetre Image of a Stellar Cradle [Preview - JPEG: 400 x 627 pix - 200k] [Normal - JPEG: 800 x 1254 pix - 503k] [Full Res - JPEG: 1539 x 2413 pix - 1.3M] Caption: ESO PR Photo 30/05 is an image of the giant molecular cloud G327 taken with APEX. More than 5000 spectra were taken in the J=3-2 line of the carbon monoxide molecule (CO), one of the best tracers of molecular clouds, in which star formation takes place. The bright peak in the north of the cloud is an evolved star forming region, where the gas is heated by a cluster of new stars. The most interesting region in the image is totally inconspicuous in CO: the G327 hot core, as seen in methanol contours. It is a truly exceptional source, and is one of the richest sources of emission from complex organic molecules in the

  5. Modelling the spectral response of the desert tree Prosopis tamarugo to water stress

    NARCIS (Netherlands)

    Chávez Oyanadel, R.O.; Clevers, J.G.P.W.; Herold, M.; Ortiz, M.; Acevedo, E.

    2013-01-01

    In this paper, we carried out a laboratory experiment to study changes in canopy reflectance of Tamarugo plants under controlled water stress. Tamarugo (Prosopis tamarugo Phil.) is an endemic and endangered tree species adapted to the hyper-arid conditions of the Atacama Desert, Northern Chile. Obse

  6. The Presence and Distribution of Salts as a Palaeoprecipitation Proxy in Atacama Soils

    Science.gov (United States)

    McKay, Lucy; Claire, Mark

    2016-04-01

    The Atacama Desert in northern Chile (17 to 27° S) is the driest and oldest warm desert on Earth and contains unique abundances of atmospherically-derived salts such as nitrate and perchlorate (Ewing et al., 2006; Jackson et al., 2015). Near-surface accumulation of extremely soluble salts indicates a scarcity of long-term precipitation-driven leaching from Atacama soils. The prolonged absence of substantial precipitation has enabled nitrate and perchlorate to accumulate for millions of years to measurable levels, while interacting with occasional rainfall to move vertically through the soil profile. We investigate the near-surface presence and distribution of atmospherically-generated soluble salts at Earth's most arid extreme, aiming to quantify Atacama palaeoprecipitation during the Quaternary. Previous field and modelling studies have revealed a strong correlation between the depth of peak nitrate and past precipitation events in the U.S. desert southwest (Walvoord et al., 2003; Marion et al., 2008). We extend these studies to regions of much lower rainfall, and report the largest ever near-surface concentrations of nitrate and perchlorate in Earth's soils. We present salt distribution profiles from soil pits in six localities, spanning ~1000 km of the south-to-north (27° to 24° S) natural rainfall and ecosystem function gradient that spans the arid to hyperarid transition (from 20 to 100 mg/kg at 120 cm depth, with an astonishing 22 mg/kg at the surface. In comparison, perchlorate peaks at ~4 mg/kg at 90 cm depth in our Yungay soil profile. Given that perchlorate is the most soluble naturally-existing salt, "km40" and "PONR" indicate a complete lack of recent precipitation and are candidates for the driest place on Earth. We use the numerical model of Marion et al. (2008) to quantitatively constrain the maximum rainfall distributions and event frequencies that are permitted by our measured profiles. Our Atacama soil profiles exhibit vertical variation in

  7. Desert Scrublands

    Science.gov (United States)

    Jones, L.L.C.; Halama, K.J.; Lovich, R.E.

    2016-01-01

    Desert scrublands comprise the lower to mid-elevation portions of four different ecosystems including the Chihuahuan, Great Basin, Mojave and Sonoran Deserts. Together the area inside their outer boundaries includes over 8% of the surface area of the United States. Despite significant differences in the flora and fauna of these bioregions they all share the common trait of being arid shrub-steppe ecosystems, receiving, on average, less than 254 mm of rain per year. The austere nature of these landscapes belies their significant biodiversity, the amazing behavioral and physiological adaptations of the biota, and the fragility of the ecosystems to human disturbances. For example, the Mojave Desert alone has at least 250 species of ephemeral plants, mostly winter annuals, and up to 90% are endemic.

  8. Object-based analysis of 8-bands Worldview2 imagery for assessing health condition of desert trees

    NARCIS (Netherlands)

    Chávez Oyanadel, R.O.; Clevers, J.G.P.W.

    2012-01-01

    High spatial resolution panchromatic and multispectral WorldView2 images were used to assess the health condition of Tamarugo (Prosopis tamarugo Phil.) trees in the hyperarid Atacama desert in Northern Chile. Tamarugo is a very valuable species for biodiversity conservation due to its endemic charac

  9. Assessing water stress of desert Tamarugo trees using in situ data and very high spatial resolution remote sensing

    NARCIS (Netherlands)

    Chávez Oyanadel, R.O.; Clevers, J.G.P.W.; Herold, M.; Acevedo, E.; Ortiz, M.

    2013-01-01

    The hyper-arid Atacama Desert is one of the most extreme environments for life and only few species have evolved to survive its aridness. One such species is the tree Prosopis tamarugo Phil. Because Tamarugo completely depends on groundwater, it is being threatened by the high water demand from the

  10. Characterizing Atacama B-mode Search Detectors with a Half-Wave Plate

    CERN Document Server

    Simon, S M; Campusano, L E; Choi, S K; Crowley, K T; Essinger-Hileman, T; Gallardo, P; Ho, S P; Kusaka, A; Nati, F; Palma, G A; Page, L A; Raghunathan, S; Staggs, S T

    2015-01-01

    The Atacama B-Mode Search (ABS) instrument is a cryogenic ($\\sim$10 K) crossed-Dragone telescope located at an elevation of 5190 m in the Atacama Desert in Chile that observed for three seasons between February 2012 and October 2014. ABS observed the Cosmic Microwave Background (CMB) at large angular scales ($40<\\ell<500$) to limit the B-mode polarization spectrum around the primordial B-mode peak from inflationary gravity waves at $\\ell \\sim100$. The ABS focal plane consists of 480 transition-edge sensor (TES) bolometers. They are coupled to orthogonal polarizations from a planar ortho-mode transducer (OMT) and observe at 145 GHz. ABS employs an ambient-temperature, rapidly rotating half-wave plate (HWP) to mitigate systematic effects and move the signal band away from atmospheric $1/f$ noise, allowing for the recovery of large angular scales. We discuss how the signal at the second harmonic of the HWP rotation frequency can be used for data selection and for monitoring the detector responsivities.

  11. The Atacama B-Mode Search: CMB Polarimetry with Transition-Edge-Sensor Bolometers

    CERN Document Server

    Essinger-Hileman, T; Beall, J A; Cho, H M; Fowler, J; Halpern, M; Hasselfield, M; Irwin, K D; Marriage, T A; Niemack, M D; Page, L; Parker, L P; Pufu, S; Staggs, S T; Stryzak, O; Visnjic, C; Yoon, K W; Zhao, Y

    2010-01-01

    The Atacama B-mode Search (ABS) experiment is a 145 GHz polarimeter designed to measure the B-mode polarization of the Cosmic Microwave Background (CMB) at large angular scales. The ABS instrument will ship to the Atacama Desert of Chile fully tested and ready to observe in 2010. ABS will image large-angular-scale CMB polarization anisotropies onto a focal plane of 240 feedhorn-coupled, transition-edge sensor (TES) polarimeters, using a cryogenic crossed-Dragone design. The ABS detectors, which are fabricated at NIST, use orthomode transducers to couple orthogonal polarizations of incoming radiation onto separate TES bolometers. The incoming radiation is modulated by an ambient-temperature half-wave plate in front of the vacuum window at an aperture stop. Preliminary detector characterization indicates that the ABS detectors can achieve a sensitivity of 300 $\\mu K \\sqrt{s}$ in the field. This paper describes the ABS optical design and detector readout scheme, including feedhorn design and performance, magneti...

  12. A geomorphological approach to determining the Neogene to Recent tectonic deformation in the Coastal Cordillera of northern Chile (Atacama)

    Science.gov (United States)

    Riquelme, R.; Martinod, J.; Hérail, G.; Darrozes, J.; Charrier, R.

    2003-01-01

    The large (≈10000 km 2) and local-scale (Atacama Fault System (AFS) accommodated the relative uplift of the western side of the Chilean Coastal Cordillera of the Chañaral region (southern Atacama Desert). The mean regional altitude systematically decreases eastwards crossing the AFS, independent of the lithological characteristics of the substratum cut by this system of faults. Topographic analysis reveals a more incised landscape west of the AFS that, at the local scale, is reported by the distribution of the altitudes (hypsometric curves and integrals) of tributary basins and by the presence of terraces. In the Middle and Upper Miocene, a thick (>300 m) sedimentary succession was deposited east of the AFS. The succession fills previously deep paleovalleys. And it consists of gravel, so-called "Atacama Gravels", which passes laterally into fine-grained playa related deposits near the AFS. We interpret the deposition of this succession as a result of a blocking closure of the valley flowing from the Precordillera due to the activity on AFS. A pedimentation episode followed sediment deposition and is locally strongly re-incised by the main modern-day river valleys draining the Precordillera. Incision may result from either regional uplift of the forearc, and/or from more localized activity on the AFS. Furthermore, Recent (Quaternary?) tectonic activity on the AFS has been observed which is consistent with a localized relative uplift of the crustal block west of the AFS.

  13. Description of a very dense meteorite collection area in western Atacama: Insight into the long-term composition of the meteorite flux to Earth

    Science.gov (United States)

    Hutzler, Aurore; Gattacceca, JéRôMe; Rochette, Pierre; Braucher, RéGis; Carro, Bertrand; Christensen, Eric J.; Cournede, CéCile; Gounelle, Matthieu; Laridhi Ouazaa, Nejia; Martinez, Rodrigo; Valenzuela, Millarca; Warner, Michael; Bourles, Didier

    2016-03-01

    We describe the geological, morphological, and climatic settings of two new meteorite collections from Atacama (Chile). The "El Médano collection" was recovered by systematic on-foot search in El Médano and Caleta el Cobre dense collection areas and is composed of 213 meteorites before pairing, 142 after pairing. The "private collection" has been recovered by car by three private hunters and consists of 213 meteorites. Similar to other hot desert finds, and contrary to the falls and Antarctica finds, both collections show an overabundance of H chondrites. A recovery density can be calculated only for the El Médano collection and gives 251 and 168 meteorites larger than 10 g km-2, before and after pairing, respectively. It is by far the densest collection area described in hot deserts. The Atacama Desert is known to have been hyperarid for a long period of time and, based on cosmic-ray exposure ages on the order of 1-10 Ma, to have been stable over a period of time of several million years. Such a high meteorite concentration might be explained invoking either a yet unclear concentration mechanism (possibly related to downslope creeping) or a previously underestimated meteorite flux in previous studies or an average terrestrial age over 2 Myr. This last hypothesis is supported by the high weathering grade of meteorites and by the common terrestrial fragmentation (with fragments scattered over a few meters) of recovered meteorites.

  14. Miracles in a Desert

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    People find new ways to harness the Ulan Buh Desert Going into the heart of the Ulan Buh Desert in north China’s Inner Mongolia Autonomous Region, one will be astonished by a large stretch of water.

  15. Modified Desert Cooler (MDC

    Directory of Open Access Journals (Sweden)

    CHANDRAKANT B. KOTHARE,

    2011-04-01

    Full Text Available “Modified Desert Cooler (MDC” as the name suggest that it is the modification of the conventional cooler. It is the Air Conditioner cum refrigerator for people who cannot afford costly equipments like air conditioner, refrigerator and other such appliances. It cools the air more than the conventional Desert cooler. The modified desert cooler is developed for providing better cooling effect than conventional desert cooler. It also provides cold-pure water for drinking purpose comparatively at low cost than Refrigerator with the help of modifies Matka attached with it. It also decreased moisture content of the air coming through desert cooler upto someextent. The MDC consists of a desert cooler with storage box, two concentric simple small size earthen pot known as modify Matka, a purifier, humidity controller and connecting tubes or pipes. Storage box provided in the desert cooler can be used to store regular food items, vegetables, fruits etc.

  16. Solar Simulations for the Atacama Large Millimeter Observatory Network

    CERN Document Server

    Wedemeyer, Sven; Brajsa, Roman; Barta, Miroslav; Shimojo, Masumi

    2015-01-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) will be a valuable tool for observing the chromosphere of our Sun at (sub-)millimeter wavelengths at high spatial, temporal and spectral resolution and as such has great potential to address long-standing scientific questions in solar physics. In order to make the best use of this scientific opportunity, the Solar Simulations for the Atacama Large Millimeter Observatory Network has been initiated. A key goal of this international collaboration is to support the preparation and interpretation of future observations of the Sun with ALMA.

  17. Thermal Performance of Traditional and New Concept Houses in the Ancient Village of San Pedro De Atacama and Surroundings

    Directory of Open Access Journals (Sweden)

    Massimo Palme

    2014-05-01

    Full Text Available Earth, wood and others traditional materials are still used in house constructions in many regions of the world, especially in the Andes. San Pedro de Atacama, for example, is a small town where earth blocks (adobes and rammed earth (tapial are important ways to construct, an art passed on through generations. Energy properties of earth are very interesting: thermal conductivity is low; heat storage capacity is high; color is variable and can be used to absorb or to reject solar radiation. However, nowadays the government social dwelling service is proposing a different type of construction, which does not maintain any relation with the tradition. This paper presents simulation studies and monitoring of four different San Pedro houses, constructed by using different techniques and materials. Results can be used to discuss the thermal performance needed in desert climate and the reliability of social dwelling service houses, under construction at this time in the town.

  18. Soil Formation and Transport Processes on Hillslopes along a Precipitation Gradient in the Atacama Desert, Chile

    OpenAIRE

    Owen, Justine J.

    2009-01-01

    The climate-dependency of the rates and types of soil formation processes on level landforms has been recognized and documented for decades. In contrast, methods for quantifying rates of soil formation and transport on hillslopes have only recently been developed and the results suggest that these rates are independent of climate. One explanation for this discrepancy is that hillslopes and their soil mantles are dynamic systems affected by local and regional tectonic effects. Tectonics can ch...

  19. Paleomagnetism and tectonics of the southern Atacama Desert (25-28°S), northern Chile

    OpenAIRE

    ARRIAGADA, César; Roperch, Pierrick; Mpodozis, Constantino; Fernandez, Rodrigo

    2006-01-01

    International audience; We report paleomagnetic results for 131 sites from the modern forearc of northern Chile (25°S and 28°S). Remanent magnetization in volcanic and intrusive rocks is mostly primary, while a secondary magnetization is observed in sedimentary rocks. Comparison of locality-mean directions with expected paleomagnetic directions indicates vertical axis rotations from -7.3° +/- 21.6° counterclockwise to 52.7° +/- 17° clockwise. Jurassic to Early Cretaceous rocks from the Coasta...

  20. Astronomers Break Ground on Atacama Large Millimeter Array (ALMA) - World's Largest Millimeter Wavelength Telescope

    Science.gov (United States)

    2003-11-01

    for a spectacular new instrument, " stated Dr. Rita Colwell , director of the U.S. National Science Foundation. " ALMA will expand our vision of the Universe with "eyes" that pierce the shrouded mantles of space through which light cannot penetrate." On the occasion of this groundbreaking, the ALMA logo was unveiled. [ALMA Logo] Science with ALMA ALMA will capture millimetre and sub-millimetre radiation from space and produce images and spectra of celestial objects as they appear at these wavelengths. This particular portion of the electromagnetic spectrum, which is less energetic than visible and infrared light, yet more energetic than most radio waves, holds the key to understanding a great variety of fundamental processes, e.g., planet and star formation and the formation and evolution of galaxies and galaxy clusters in the early Universe. The possibility to detect emission from organic and other molecules in space is of particularly high interest. The millimetre and sub-millimetre radiation that ALMA will study is able to penetrate the vast clouds of dust and gas that populate interstellar (and intergalactic) space, revealing previously hidden details about astronomical objects. This radiation, however, is blocked by atmospheric moisture (water molecules) in the Earth's atmosphere. To conduct research with ALMA in this critical portion of the spectrum, astronomers thus need an exceptional observation site that is very dry, and at a very high altitude where the atmosphere above is thinner. Extensive tests showed that the sky above the high-altitude Chajnantor plain in the Atacama Desert has the unsurpassed clarity and stability needed to perform efficient observations with ALMA . ALMA operation ALMA will be the highest-altitude, full-time ground-based observatory in the world, at some 250 metres higher than the peak of Mont Blanc, Europe's tallest mountain. Work at this altitude is difficult. To help ensure the safety of the scientists and engineers at ALMA

  1. The great Atacama flood of 2001 and its implications for Andean hydrology

    Science.gov (United States)

    Houston, John

    2006-02-01

    In February 2001, widespread flooding occurred throughout the Atacama Desert of northern Chile and southern Peru. It was particularly severe in the Río Loa basin, where roads and bridges were disrupted and the town of Calama inundated. The instantaneous peak flow in the Río Salado, a tributary of the Río Loa, reached 310 m3 s-1, an order of magnitude higher than any previously recorded event. The flood is estimated to have a return period of 100-200 years and is shown to have been caused by intense, long-duration rainfall in the western Cordillera associated with La Niña. The surface water response is typical of arid areas and highly dependent on antecedent conditions, but is quite different in perennial and ephemeral catchments. Ephemeral flood flows suffer high transmission losses, recharging phreatic aquifers. Perennial rivers have lower runoff coefficients, but baseflow levels remained high after the event for several months due to bank storage rebound and interflow. Extremely high energies of 3000 W m-2 were generated by the floods in the Cordillera, becoming less in the Precordillera and downstream. Erosion and sediment transport were consequently highest in the upper and middle reaches of the rivers, with mixed erosion-deposition in the lowest reach. The new insights gained from the interpretation and quantification of this event have important implications for palaeoenvironmental analysis, hazard management, water resource evaluation and the palaeohydrological evolution of the Andes.

  2. Gopherus agassizii (Desert Tortoise). Non-native seed dispersal

    Science.gov (United States)

    Ennen, J.R.; Loughran, Caleb L.; Lovich, Jeffrey E.

    2011-01-01

    Sahara Mustard (Brassica tournefortii) is a non-native, highly invasive weed species of southwestern U.S. deserts. Sahara Mustard is a hardy species, which flourishes under many conditions including drought and in both disturbed and undisturbed habitats (West and Nabhan 2002. In B. Tellman [ed.], Invasive Plants: Their Occurrence and Possible Impact on the Central Gulf Coast of Sonora and the Midriff Islands in the Sea of Cortes, pp. 91–111. University of Arizona Press, Tucson). Because of this species’ ability to thrive in these habitats, B. tournefortii has been able to propagate throughout the southwestern United States establishing itself in the Mojave and Sonoran Deserts in Arizona, California, Nevada, and Utah. Unfortunately, naturally disturbed areas created by native species, such as the Desert Tortoise (Gopherus agassizii), within these deserts could have facilitated the propagation of B. tournefortii. (Lovich 1998. In R. G. Westbrooks [ed.], Invasive Plants, Changing the Landscape of America: Fact Book, p. 77. Federal Interagency Committee for the Management of Noxious and Exotic Weeds [FICMNEW], Washington, DC). However, Desert Tortoises have never been directly observed dispersing Sahara Mustard seeds. Here we present observations of two Desert Tortoises dispersing Sahara Mustard seeds at the interface between the Mojave and Sonoran deserts in California.

  3. Digital Spectro-Correlator System for the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array

    CERN Document Server

    Kamazaki, T; Chikada, Y; Okuda, T; Kurono, Y; Iguchi, S; Mitsuishi, S; Murakami, Y; Nishimuta, N; Mita, H; Sano, R

    2011-01-01

    We have developed an FX-architecture digital spectro-correlator for the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeter Array. The correlator is able to simultaneously process four pairs of dual polarization signals with the bandwidth of 2 GHz, which are received by up to sixteen antennas. It can calculate auto- and cross-correlation spectra including cross-polarization in all combinations of all the antennas, and output correlation spectra with flexible spectral configuration such as multiple frequency ranges and multiple frequency resolutions. Its spectral dynamic range is estimated to be higher than 10^4 relative to Tsys from processing results of thermal noise for eight hours with a typical correlator configuration. The sensitivity loss is also confirmed to be 0.9 % with the same configuration. In this paper, we report the detailed design of the correlator and the verification results of the developed hardware.

  4. Sensors for Desert Surveillance

    Directory of Open Access Journals (Sweden)

    B. S. Chauhan

    2005-10-01

    Full Text Available Various types of sensors-visible, passive night vision, infrared, synthetic aperture radar, etc can be used for desert surveillance. The surveillance capability of these sensors depends to a large extent, on various atmospheric effects, viz., absorption, scattering, aerosol, turbulence, and optical mirage. In this paper, effects of various atmospheric phenomena on the transmission of signals, merits and demerits of different means of surveillance under desert environmental conditions are discussed. Advanced surveillance techniques, ie, multisensor fusion, multi and hyperspectral imaging, having special significance for desert surveillance, have also been discussed.

  5. Ckoirama, the first Chilean--state owned observatory under desert skies

    Science.gov (United States)

    Char, F.; Unda-Sanzana, E.; Colque, J.; Fossey, S.; Rocchetto, M.

    2016-08-01

    The following work wants to introduce Ckoirama, the first public professional observatory of Chile, under the clear skies of the Atacama desert. Operated by the Unidad de Astronomia of the Universidad de Antofagasta, it was conceived to perform scientific operations, through its main 0.6 m telescope, but it will also be open for educational purposes, communicating astronomy to the public through a secondary 0.35 m telescope. Ckoirama will not only be an opportunity to make autonomous observations; this is also an important message to the astronomical community, because this is the first step toward a highlighted presence of Chile and a new commitment to invest in the astronomical research.

  6. The shallow-water chitons (Mollusca, Polyplacophora of Caldera, Region of Atacama, northern Chile

    Directory of Open Access Journals (Sweden)

    Juan Francisco Araya

    2015-03-01

    Full Text Available The Molluscan species of the northern littoral of Chile have been sparsely studied. This work reviews for the first time the diversity of polyplacophoran molluscs around the port of Caldera, in the Region of Atacama (26°45’49”S; 70°45’17”W to 27°20’23”S; 70°56’46”W, northern Chile. Eleven species were found in this study: Acanthopleura echinata (Barnes, 1824; Callistochiton pulchellus (Gray, 1828; Calloplax vivipara (Plate, 1899, Chaetopleura peruviana (Lamarck, 1819; Chiton cumingsii Frembly, 1827; Chiton granosus Frembly, 1827; Chiton magnificus Deshayes, 1827; Enoplochiton niger (Barnes, 1824, Radsia barnesii (Gray, 1828, Tonicia atrata (G. B. Sowerby II, 1840 and Tonicia chilensis (Frembly, 1827. All of the species occurring in the area have distributions in the southeastern Pacific Ocean, from Ecuador to central Chile, and three of them are species endemic to the Chilean coasts (Calloplax vivipara, Radsia barnesii, and Tonicia atrata. This diversity of species is comparable to that of better surveyed faunas of central and southern Chile or Patagonia. Of the eleven species recorded, the geographic distribution records for Callistochiton pulchellus, Radsia barnesii and Tonicia atrata are extended, and Calloplax vivipara is found alive again after 40 years, filling a gap in its known distribution. Illustrations of living specimens in their habitat, distribution records and a taxonomic key for all the studied taxa are also provided.

  7. Estacionalidad de las muertes en la puna de Atacama

    Directory of Open Access Journals (Sweden)

    Bejarano, Ignacio

    2001-01-01

    Full Text Available En distintas culturas y geografías la mortalidad se distribuye de acuerdo a un patrón estacional variable según las poblaciones. El objetivo de este trabajo fue analizar la estacionalidad de las muertes en un medio ambiente extremo como lo es la Puna de Atacama (PA. Los datos de defunciones (1890-1950 corresponden a dos localidades de la PA: Susques y San Pedro de Atacama. En el análisis se consideraron, por sexo, tres grupos de edad: a prerreproductiva (0-15 años (PRE, reproductiva (16-44 años (REP y postreproductiva (<45 años (POS. Se calculo el coeficiente de estacionalidad de Henry y para identificar estadísticamente variaciones estacionales se aplicó una prueba de homogeneidad. Se utilizó la prueba de Edwards para detectar ciclos armónicos en la distribución de muertes. Independientemente de la edad y el sexo se observó un patron estacional diferencial significativo que responde a un modelo de variación armónica simple, los coeficientes de Henry mas altos se presentaron en verano e invierno. Cuando se analiza la estacionalidad por grupo de edad y sexo el patrón previamente descripto se mantiene sólo en las edades REP y POS y en el sexo masculino. Este estudio proporciona un indicio del comportamiento de la estacionalidad de las muertes en la Puna de Atacama. Sin embargo no difiere del observado en poblaciones contemporáneas de países desarrollados, por lo que se concluye que el patrón observado no sería consecuencia directa de las condiciones climáticas, culturales, etc. de este ambiente extremo.

  8. REMOTE SENSING-BASED DETECTION AND SPATIAL PATTERN ANALYSIS FOR GEO-ECOLOGICAL NICHE MODELING OF TILLANDSIA SPP. IN THE ATACAMA, CHILE

    Directory of Open Access Journals (Sweden)

    N. Wolf

    2016-06-01

    Full Text Available In the coastal Atacama Desert in Northern Chile plant growth is constrained to so-called ‘fog oases’ dominated by monospecific stands of the genus Tillandsia. Adapted to the hyperarid environmental conditions, these plants specialize on the foliar uptake of fog as main water and nutrient source. It is this characteristic that leads to distinctive macro- and micro-scale distribution patterns, reflecting complex geo-ecological gradients, mainly affected by the spatiotemporal occurrence of coastal fog respectively the South Pacific Stratocumulus clouds reaching inlands. The current work employs remote sensing, machine learning and spatial pattern/GIS analysis techniques to acquire detailed information on the presence and state of Tillandsia spp. in the Tarapacá region as a base to better understand the bioclimatic and topographic constraints determining the distribution patterns of Tillandsia spp. Spatial and spectral predictors extracted from WorldView-3 satellite data are used to map present Tillandsia vegetation in the Tarapaca region. Regression models on Vegetation Cover Fraction (VCF are generated combining satellite-based as well as topographic variables and using aggregated high spatial resolution information on vegetation cover derived from UAV flight campaigns as a reference. The results are a first step towards mapping and modelling the topographic as well as bioclimatic factors explaining the spatial distribution patterns of Tillandsia fog oases in the Atacama, Chile.

  9. Remote Sensing-Based Detection and Spatial Pattern Analysis for Geo-Ecological Niche Modeling of Tillandsia SPP. In the Atacama, Chile

    Science.gov (United States)

    Wolf, N.; Siegmund, A.; del Río, C.; Osses, P.; García, J. L.

    2016-06-01

    In the coastal Atacama Desert in Northern Chile plant growth is constrained to so-called `fog oases' dominated by monospecific stands of the genus Tillandsia. Adapted to the hyperarid environmental conditions, these plants specialize on the foliar uptake of fog as main water and nutrient source. It is this characteristic that leads to distinctive macro- and micro-scale distribution patterns, reflecting complex geo-ecological gradients, mainly affected by the spatiotemporal occurrence of coastal fog respectively the South Pacific Stratocumulus clouds reaching inlands. The current work employs remote sensing, machine learning and spatial pattern/GIS analysis techniques to acquire detailed information on the presence and state of Tillandsia spp. in the Tarapacá region as a base to better understand the bioclimatic and topographic constraints determining the distribution patterns of Tillandsia spp. Spatial and spectral predictors extracted from WorldView-3 satellite data are used to map present Tillandsia vegetation in the Tarapaca region. Regression models on Vegetation Cover Fraction (VCF) are generated combining satellite-based as well as topographic variables and using aggregated high spatial resolution information on vegetation cover derived from UAV flight campaigns as a reference. The results are a first step towards mapping and modelling the topographic as well as bioclimatic factors explaining the spatial distribution patterns of Tillandsia fog oases in the Atacama, Chile.

  10. Ivory Coast.

    Science.gov (United States)

    1985-07-01

    Since the Ivory Coast's independence (1960), the population has increased from 3.7 million to 9.7 million, representing a growth rate of up to 4.2%. The country's 5th 5-Year Plan (1981-85) has 4 priorities: 1) agricultural modernization, 2) traditional industry and crafts modernization, 3) human resources enhancement, and 4) continued economic growth. Population objectives include 1) increasing peasant aid, 2) making education more development oriented, 3) making health care more accessible, and 4) finding solutions to employment and unemployment problems. The government wants to increase population size because it needs labor for economic development. Programs 1) develop areas with high out-migration, 2) reduce maternal and child mortality, and 3) support family planning only to benefit family well being. Although the Ivory Coast's population will reach 15 million by the year 2000, and population density has tripled since 1950, the country is still thinly populated. The current population policy strives to 1) reduce infant mortality, 2) maintain fertility, and 3) diminish immigration and emigration. Life expectancy is 47 years, infant mortality is 122/1000, and most rural people have no health services. The government considers the total fertility rate of 6.7 satisfactory. Abortion for contraceptive purposes and sterilization are illegal; access to contraception is limited. The Ivory Coast, because of rapid economic growth, attracts immigrants from neighboring countries; at present 1/3 of the population is foreign-born. The government is trying to integrate natives more fully into the labor force. There is little emigration, but internal migration involves almost half of the population. The government attempts to 1) slow down and redirect rural to urban migration to small and medium sized towns and 2) slow rural to rural migration from the savannah to the forest zone.

  11. The Atacama Cosmology Telescope: Cross Correlation with Planck maps

    CERN Document Server

    Louis, Thibaut; Hasselfield, Matthew; Bond, J Richard; Calabrese, Erminia; Das, Sudeep; Devlin, Mark J; Dunkley, Joanna; Dünner, Rolando; Gralla, Megan; Hajian, Amir; Hincks, Adam D; Hlozek, Renée; Huffenberger, Kevin; Infante, Leopoldo; Kosowsky, Arthur; Marriage, Tobias A; Moodley, Kavilan; Næss, Sigurd; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Partridge, Bruce; Sehgal, Neelima; Sievers, Jonathan L; Spergel, David N; Staggs, Suzanne T; Walter, Benjamin Z; Wollack, Edward J

    2014-01-01

    We present the temperature power spectrum of the Cosmic Microwave Background obtained by cross-correlating maps from the Atacama Cosmology Telescope (ACT) at 148 and 218 GHz with maps from the Planck satellite at 143 and 217 GHz, in two overlapping regions covering 592 square degrees. We find excellent agreement between the two datasets at both frequencies, quantified using the variance of the residuals between the ACT power spectra and the ACTxPlanck cross-spectra. We use these cross-correlations to calibrate the ACT data at 148 and 218 GHz, to 0.7% and 2% precision respectively. We find no evidence for anisotropy in the calibration parameter. We compare the Planck 353 GHz power spectrum with the measured amplitudes of dust and cosmic infrared background (CIB) of ACT data at 148 and 218 GHz. We also compare planet and point source measurements from the two experiments.

  12. The Atacama Cosmology Telescope: cross correlation with Planck maps

    Energy Technology Data Exchange (ETDEWEB)

    Louis, Thibaut; Calabrese, Erminia; Dunkley, Joanna; Næss, Sigurd [Department of Astrophysics, Oxford University, Oxford OX1 3RH (United Kingdom); Addison, Graeme E.; Hincks, Adam D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Hasselfield, Matthew; Hlozek, Renée [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Bond, J. Richard; Hajian, Amir [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Das, Sudeep [Argonne National Laboratory, 9700 S. Cass Ave., Lemont, IL 60439 (United States); Devlin, Mark J. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, U.S.A (United States); Dünner, Rolando; Infante, Leopoldo [Departamento de Astronomía y Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Gralla, Megan; Marriage, Tobias A. [Dept. of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Huffenberger, Kevin [Department of Physics, Florida State University, Keen Physics Building, 77 Chieftan Way, Tallahassee, Florida (United States); Kosowsky, Arthur [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260 (United States); Moodley, Kavilan [Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, University of KwaZulu-Natal, Durban, 4041 (South Africa); Niemack, Michael D., E-mail: Thibaut.Louis@astro.ox.ac.uk [Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States); and others

    2014-07-01

    We present the temperature power spectrum of the Cosmic Microwave Background obtained by cross-correlating maps from the Atacama Cosmology Telescope (ACT) at 148 and 218 GHz with maps from the Planck satellite at 143 and 217 GHz, in two overlapping regions covering 592 square degrees. We find excellent agreement between the two datasets at both frequencies, quantified using the variance of the residuals between the ACT power spectra and the ACT × Planck cross-spectra. We use these cross-correlations to measure the calibration of the ACT data at 148 and 218 GHz relative to Planck, to 0.7% and 2% precision respectively. We find no evidence for anisotropy in the calibration parameter. We compare the Planck 353 GHz power spectrum with the measured amplitudes of dust and cosmic infrared background (CIB) of ACT data at 148 and 218 GHz. We also compare planet and point source measurements from the two experiments.

  13. The Atacama Cosmology Telescope: cross correlation with Planck maps

    International Nuclear Information System (INIS)

    We present the temperature power spectrum of the Cosmic Microwave Background obtained by cross-correlating maps from the Atacama Cosmology Telescope (ACT) at 148 and 218 GHz with maps from the Planck satellite at 143 and 217 GHz, in two overlapping regions covering 592 square degrees. We find excellent agreement between the two datasets at both frequencies, quantified using the variance of the residuals between the ACT power spectra and the ACT × Planck cross-spectra. We use these cross-correlations to measure the calibration of the ACT data at 148 and 218 GHz relative to Planck, to 0.7% and 2% precision respectively. We find no evidence for anisotropy in the calibration parameter. We compare the Planck 353 GHz power spectrum with the measured amplitudes of dust and cosmic infrared background (CIB) of ACT data at 148 and 218 GHz. We also compare planet and point source measurements from the two experiments

  14. Southwestern desert resources

    Science.gov (United States)

    Halvorson, William L.; van Riper, Charles; Schwalbe, Cecil R.

    2010-01-01

    The southwestern deserts stretch from southeastern California to west Texas and then south to central Mexico. The landscape of this region is known as basin and range topography featuring to "sky islands" of forest rising from the desert lowlands which creates a uniquely diverse ecology. The region is further complicated by an international border, where governments have caused difficulties for many animal populations. This book puts a spotlight on individual research projects which are specific examples of work being done in the area and when they are all brought together, to shed a general light of understanding the biological and cultural resources of this vast region so that those same resources can be managed as effectively and efficiently as possible. The intent is to show that collaborative efforts among federal, state agency, university, and private sector researchers working with land managers, provides better science and better management than when scientists and land managers work independently.

  15. Stabilization of Desert Surfaces and Accumulation of Dust Under Biological Soil Crusts

    Science.gov (United States)

    Finstad, K. M.; Mcnicol, G.; Pfeiffer, M.; Amundson, R.

    2014-12-01

    Biological soil crusts (BSC) are known to play a critical role in the stabilization of desert surfaces by helping to protect sediment from wind and water erosion and aiding in the trapping of airborne particles. The crusts are often composed of cyanobacteria, algae, and fungi, and occupy the upper few cm of a soil. Due to their high tolerance of desiccation and ability to utilize fog and dew sources, BSC are able to exist in environments that may otherwise be too dry for vascular plants. In the hyperarid Atacama Desert, decades or more between measurable precipitation events has created a landscape devoid of macroscopic life. While precipitation is rare, coastal fog occurs regularly and microbial communities capable of utilizing fog and dew water are able to persist. Here we found cyanobacteria and lichen living in association with a thin sulfate and dust crust (~2 cm) covering the surface of 'dust plateaus'. Topographically the region is highly irregular and part of a largely erosional landscape. We hypothesized that these flat-topped plateaus are accretionary features that have been able to maintain dust accumulation for thousands of years as a result of the surface crusts. To test this hypothesis we conducted radiocarbon analysis of crusts and soil profiles at two sites approximately 30 km apart, one in a high fog zone and another in lower fog frequency zone. The radiocarbon analysis shows that sediment has been accumulating in the 'plateaus' for the past 15,000 years and that biological activity and rates of C cycling in the crust increase with increasing fog frequency and intensity. The ages of organic material in the dust decrease monotonically with decreasing soil thickness, suggestive of progressive upward growth by dust accumulation. Our data indicate that the BSC are capable of surviving in hyperarid the Atacama Desert, a Mars analogue, through the utilization of fog water, and that their presence can leave a visible geomorphic imprint on the landscape.

  16. Libyan Desert, Libya, Africa

    Science.gov (United States)

    1992-01-01

    Desert landscapes such as this part of the northern Sahara (27.0N, 11.0E) may be analogous to other planets which have no soil or plant growth. The dark rocks in this view are probably volcanic in origin and have many stream beds leading into the dune areas. These stream beds carry sediments towards the lower terrain where the water evaporates, leaving the sediments to be wind blown into the complex dune patterns. The red color comes from iron oxides.

  17. Physiological adaptation in desert birds

    NARCIS (Netherlands)

    Williams, JB; Tieleman, BI; Williams, Joseph B.

    2005-01-01

    We call into question the idea that birds have not evolved unique physiological adaptations to desert environments. The rate at which desert larks metabolize energy is lower than in mesic species within the same family, and this lower rate of living translates into a lower overall energy requirement

  18. The Atacama Cosmology Telescope: CMB Polarization at $200<\\ell<9000$

    CERN Document Server

    Naess, Sigurd; McMahon, Jeff; Niemack, Michael D; Addison, Graeme E; Ade, Peter A R; Allison, Rupert; Amiri, Mandana; Baker, Andrew; Battaglia, Nick; Beall, James A; de Bernardis, Francesco; Bond, J Richard; Britton, Joe; Calabrese, Erminia; Cho, Hsiao-mei; Coughlin, Kevin; Crichton, Devin; Das, Sudeep; Datta, Rahul; Devlin, Mark J; Dicker, Simon R; Dunkley, Joanna; Dünner, Rolando; Fowler, Joseph W; Fox, Anna E; Gallardo, Patricio; Grace, Emily; Gralla, Megan; Hajian, Amir; Halpern, Mark; Henderson, Shawn; Hill, J Colin; Hilton, Gene C; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Ho, Patty; Hubmayr, Johannes; Huffenberger, Kevin M; Hughes, John P; Infante, Leopoldo; Irwin, Kent; Jackson, Rebecca; Klein, Jeff; Koopman, Brian; Kosowsky, Arthur; Li, Dale; Louis, Thibaut; Lungu, Marius; Madhavacheril, Mathew; Marriage, Tobias A; Maurin, Loïc; Menanteau, Felipe; Moodley, Kavilan; Munson, Charles; Newburgh, Laura; Nibarger, John; Nolta, Michael R; Page, Lyman A; Pappas, Christine; Partridge, Bruce; Rojas, Felipe; Schmitt, Benjamin; Sehgal, Neelima; Sherwin, Blake D; Sievers, Jon; Simon, Sara; Spergel, David N; Staggs, Suzanne T; Switzer, Eric R; Thornton, Robert; Trac, Hy; Tucker, Carole; Van Engelen, Alexander; Ward, Jon; Wollack, Edward J

    2014-01-01

    We report on measurements of the cosmic microwave background (CMB) and celestial polarization at 146 GHz made with the Atacama Cosmology Telescope Polarimeter (ACTPol) in its first three months of observing. Four regions of sky covering a total of 270 square degrees were mapped with an angular resolution of $1.3'$. The map noise levels in the four regions are between 11 and 17 $\\mu$K-arcmin. We present TT, TE, EE, TB, EB, and BB power spectra from three of these regions. The observed E-mode polarization power spectrum, displaying six acoustic peaks in the range $200<\\ell<3000$, is an excellent fit to the prediction of the best-fit cosmological models from WMAP9+ACT and Planck data. The polarization power spectrum, which mainly reflects primordial plasma velocity perturbations, provides an independent determination of cosmological parameters consistent with those based on the temperature power spectrum, which results mostly from primordial density perturbations. We find that without masking any point sou...

  19. The Atacama Cosmology Telescope: Data Characterization and Map Making

    CERN Document Server

    Dünner, Rolando; Marriage, Tobias A; Sievers, Jon; Acquaviva, Viviana; Addison, Graeme E; Ade, Peter A R; Aguirre, Paula; Amiri, Mandana; Appel, John William; Barrientos, L Felipe; Battistelli, Elia S; Bond, J Richard; Brown, Ben; Burger, Bryce; Calabarese, Erminia; Chervenak, Jay; Das, Sudeep; Devlin, Mark J; Dicker, Simon R; Doriese, W Bertrand; Dunkley, Joanna; Essinger-Hileman, Thomas; Fisher, Ryan P; Gralla, Megan B; Fowler, Joseph W; Hajian, Amir; Halpern, Mark; Hernández-Monteagudo, Carlos; Hilton, Gene C; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Huffenberger, Kevin M; Hughes, David H; Hughes, John P; Infante, Leopoldo; Irwin, Kent D; Juin, Jean Baptiste; Kaul, Madhuri; Klein, Jeff; Kosowsky, Arthur; Lau, Judy M; Limon, Michele; Lin, Yen-Ting; Louis, Thibaut; Lupton, Robert H; Marsden, Danica; Martocci, Krista; Mauskopf, Phil; Menanteau, Felipe; Moodley, Kavilan; Moseley, Harvey; Netterfield, Calvin B; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Partridge, Bruce; Quintana, Hernán; Reid, Beth; Sehgal, Neelima; Sherwin, Blake D; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Trac, Hy; Tucker, Carole; Warne, Ryan; Wilson, Grant; Wollack, Ed; Zhao, Yue

    2012-01-01

    We present a description of the data reduction and mapmaking pipeline used for the 2008 observing season of the Atacama Cosmology Telescope (ACT). The data presented here at 148 GHz represent 12% of the 90 TB collected by ACT from 2007 to 2010. In 2008 we observed for 136 days, producing a total of 1423 hours of data (11 TB for the 148 GHz band only), with a daily average of 10.5 hours of observation. From these, 1085 hours were devoted to a 850 deg^2 stripe (11.2 hours by 9.1 deg) centered on a declination of -52.7 deg, while 175 hours were devoted to a 280 deg^2 stripe (4.5 hours by 4.8 deg) centered at the celestial equator. We discuss sources of statistical and systematic noise, calibration, telescope pointing, and data selection. Out of 1260 survey hours and 1024 detectors per array, 816 hours and 593 effective detectors remain after data selection for this frequency band, yielding a 38% survey efficiency. The total sensitivity in 2008, determined from the noise level between 5 Hz and 20 Hz in the time-o...

  20. Far sidelobes measurement of the Atacama Cosmology Telescope

    Science.gov (United States)

    Dünner, Rolando; Gallardo, Patricio; Wollack, Ed; Henriquez, Fernando; Jerez-Hanckes, Carlos

    2012-09-01

    The Atacama Cosmology Telescope (ACT) is a 6m telescope designed to map the Cosmic Microwave Background (CMB) simultaneously at 145GHz, 220 GHz and 280 GHz. Its off-axis Gregorian design is intended to minimize and control the off-axis sidelobe response, which is critical for scientific purposes. The expected sidelobe level for this kind of design is less than -50 dB and can be challenging to measure. Here we present a measurement of the 145GHz far sidelobes of ACT done on the near-field of the telescope. We used a 1mW microwave source placed 13 meters away from the telescope and a chopper wheel to produce a varying signal that could be detected by the camera for different orientations of the telescope. The source feed was designed to produce a wide beam profile. Given that the coupling is expected to be dominated by diffraction over the telescope shielding structure, when combined with a measurements of the main beam far field response, these measurement can be used to validate elements of optical design and constrain the level of spurious coupling at large angles. Our results show that the diffractive coupling beyond the ground screen is consistently below -75 dB, satisfying the design expectations.

  1. Survey strategy optimization for the Atacama Cosmology Telescope

    CERN Document Server

    De Bernardis, F; Hasselfield, M; Alonso, D; Bond, J R; Calabrese, E; Choi, S K; Crowley, K T; Devlin, M; Dunkley, J; Gallardo, P A; Henderson, S W; Hilton, M; Hlozek, R; Ho, S P; Huffenberger, K; Koopman, B J; Kosowsky, A; Louis, T; Madhavacheril, M S; McMahon, J; Naess, S; Nati, F; Newburgh, L; Niemack, M D; Page, L A; Salatino, M; Schillaci, A; Schmitt, B L; Sehgal, N; Sievers, J L; Simon, S M; Spergel, D N; Staggs, S T; van Engelen, A; Vavagiakis, E M; Wollack, E J

    2016-01-01

    In recent years there have been significant improvements in the sensitivity and the angular resolution of the instruments dedicated to the observation of the Cosmic Microwave Background (CMB). ACTPol is the first polarization receiver for the Atacama Cosmology Telescope (ACT) and is observing the CMB sky with arcmin resolution over about 2000 sq. deg. Its upgrade, Advanced ACTPol (AdvACT), will observe the CMB in five frequency bands and over a larger area of the sky. We describe the optimization and implementation of the ACTPol and AdvACT surveys. The selection of the observed fields is driven mainly by the science goals, that is, small angular scale CMB measurements, B-mode measurements and cross-correlation studies. For the ACTPol survey we have observed patches of the southern galactic sky with low galactic foreground emissions which were also chosen to maximize the overlap with several galaxy surveys to allow unique cross-correlation studies. A wider field in the northern galactic cap ensured significant...

  2. Far Sidelobes Measurement of the Atacama Cosmology Telescope

    Science.gov (United States)

    Duenner, Rolando; Gallardo, Patricio; Wollack, Ed; Henriquez, Fernando; Jerez-Hanckes, Carlos

    2012-01-01

    The Atacama Cosmology Telescope (ACT) is a 6m telescope designed to map the Cosmic Microwave Background (CMB) simultaneously at 145GHz, 220 GHz and 280 GHz. Its off-axis Gregorian design is intended to minimize and control the off-axis sidelobe response, which is critical for scientific purposes. The expected sidelobe level for this kind of design is less than -50 dB and can be challenging to measure. Here we present a measurement of the 145 GHz far sidelobes of ACT done on the near-field of the telescope. We used a 1 mW microwave source placed 13 meters away from the telescope and a chopper wheel to produce a varying signal that could be detected by the camera for different orientations of the telescope. The source feed was designed to produce a wide beam profile. Given that the coupling is expected to be dominated by diffraction over the telescope shielding structure, when combined with a measurements of the main beam far field response, these measurement can be used to validate elements of optical design and constrain the level of spurious coupling at large angles. Our results show that the diffractive coupling beyond the ground screen is consistently below -75 dB, satisfying the design expectations.

  3. The Atacama Cosmology Telescope: The polarization-sensitive ACTPol instrument

    CERN Document Server

    Thornton, R J; Aiola, S; Angile, F E; Amiri, M; Beall, J A; Becker, D T; Cho, H-M; Choi, S K; Corlies, P; Coughlin, K P; Datta, R; Devlin, M J; Dicker, S R; Dunner, R; Fowler, J W; Fox, A E; Gallardo, P A; Gao, J; Grace, E; Halpern, M; Hasselfield, M; Henderson, S W; Hilton, G C; Hincks, A D; Ho, S P; Hubmayr, J; Irwin, K D; Klein, J; Koopman, B; Li, Dale; Louis, T; Lungu, M; Maurin, L; McMahon, J; Munson, C D; Naess, S; Nati, F; Newburgh, L; Nibarger, J; Niemack, M D; Niraula, P; Nolta, M R; Page, L A; Pappas, C G; Schillaci, A; Schmitt, B L; Sehgal, N; Sievers, J L; Simon, S M; Staggs, S T; Tucker, C; Uehara, M; van Lanen, J; Ward, J T; Wollack, E J

    2016-01-01

    The Atacama Cosmology Telescope (ACT) is designed to make high angular resolution measurements of anisotropies in the Cosmic Microwave Background (CMB) at millimeter wavelengths. We describe ACTPol, an upgraded receiver for ACT, which uses feedhorn-coupled, polarization-sensitive detector arrays, a 3 degree field of view, 100 mK cryogenics with continuous cooling, and meta material anti-reflection coatings. ACTPol comprises three arrays with separate cryogenic optics: two arrays at a central frequency of 148 GHz and one array operating simultaneously at both 97 GHz and 148 GHz. The combined instrument sensitivity, angular resolution, and sky coverage are optimized for measuring angular power spectra, clusters via the thermal Sunyaev-Zel'dovich and kinetic Sunyaev-Zel'dovich signals, and CMB lensing due to large scale structure. The receiver was commissioned with its first 148 GHz array in 2013, observed with both 148 GHz arrays in 2014, and has recently completed its first full season of operations with the f...

  4. A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars.

    Science.gov (United States)

    Parro, Victor; de Diego-Castilla, Graciela; Moreno-Paz, Mercedes; Blanco, Yolanda; Cruz-Gil, Patricia; Rodríguez-Manfredi, José A; Fernández-Remolar, David; Gómez, Felipe; Gómez, Manuel J; Rivas, Luis A; Demergasso, Cecilia; Echeverría, Alex; Urtuvia, Viviana N; Ruiz-Bermejo, Marta; García-Villadangos, Miriam; Postigo, Marina; Sánchez-Román, Mónica; Chong-Díaz, Guillermo; Gómez-Elvira, Javier

    2011-12-01

    The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5 m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2 m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5 g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260 g kg(-1)) and perchlorate (41.13 μg g(-1) maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14 μg g(-1)) or formate (76.06 μg g(-1)) as electron donors, and sulfate (15875 μg g(-1)), nitrate (13490 μg g(-1)), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars. PMID:22149750

  5. A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars.

    Science.gov (United States)

    Parro, Victor; de Diego-Castilla, Graciela; Moreno-Paz, Mercedes; Blanco, Yolanda; Cruz-Gil, Patricia; Rodríguez-Manfredi, José A; Fernández-Remolar, David; Gómez, Felipe; Gómez, Manuel J; Rivas, Luis A; Demergasso, Cecilia; Echeverría, Alex; Urtuvia, Viviana N; Ruiz-Bermejo, Marta; García-Villadangos, Miriam; Postigo, Marina; Sánchez-Román, Mónica; Chong-Díaz, Guillermo; Gómez-Elvira, Javier

    2011-12-01

    The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5 m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2 m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5 g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260 g kg(-1)) and perchlorate (41.13 μg g(-1) maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14 μg g(-1)) or formate (76.06 μg g(-1)) as electron donors, and sulfate (15875 μg g(-1)), nitrate (13490 μg g(-1)), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars.

  6. Measurements of Diurnal Variations of Upper Stratospheric ClO with a Ground-based Millimeter-wave Radiometer at Atacama, Chile

    Science.gov (United States)

    Kuwahara, T.; Mizuno, A.; Nagahama, T.; Maezawa, H.; Toriyama, N.; Kojima, Y.

    2010-12-01

    We present the first results of measuring the stratospheric chlorine monoxide (ClO) with a ground-based millimeter-wave radiometer at Atacama highland (23S, 68W, Alt. 4800 m), Chile. The chlorine chemistry plays an essential role in the ozone depletion in the upper stratosphere, and ClO is a key molecule for better understandings of the chlorines chemistry and the ozone recovery processes. However, measurements of the ClO distribution in the upper stratosphere are still limited at present because the ClO spectrum can be measured only in millimeter-wave region and its intensity is considerably weak. Therefore, we had newly installed a ground-based millimeter-wave radiometer equipped with a high sensitivity receiver at Atacama highland, Chile in 2004, and started monitoring the vertical profiles of the stratospheric ClO in 2008. Atacama highland is in a desert area of the northern part of Chile, being one of the most suitable places for millimeter-wave observations. Our instrument equips a superconducting (SIS) mixer receiver whose noise temperature is 170 K in double sideband at 204 GHz and a digital FFT spectrometer covering 1 GHz bandwidth with 70 kHz frequency resolution. We had continuously observed ClO spectra in 204 GHz band every 2 minutes from December 2009 to January 2010, and had obtained 11466 spectra. Vertical profiles of ClO in the upper stratosphere were retrieved from the spectra integrated every 2 hours in local time (LT) taken during 4 and 16 December. From these data, we have clearly detected a diurnal variation of ClO at 40 km. Comparing ClO mixing ratio obtained with our radiometer with those of AURA/MLS taken over our site at 12:00 - 15:00 LT, we had confirmed that they are consistent in range of errors. In this presentation, we will show the details of the diurnal variations of upper stratospheric ClO and comparisons among our results, AURA/MLS and JEM/SMILES.

  7. Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile

    Science.gov (United States)

    Fernandez, Ana B.; Rasuk, Maria C.; Visscher, Pieter T.; Contreras, Manuel; Novoa, Fernando; Poire, Daniel G.; Patterson, Molly M.; Ventosa, Antonio; Farias, Maria E.

    2016-01-01

    We combined nucleic acid-based molecular methods, biogeochemical measurements, and physicochemical characteristics to investigate microbial sedimentary ecosystems of Laguna Tebenquiche, Atacama Desert, Chile. Molecular diversity, and biogeochemistry of hypersaline microbial mats, rhizome-associated concretions, and an endoevaporite were compared with: The V4 hypervariable region of the 16S rRNA gene was amplified by pyrosequencing to analyze the total microbial diversity (i.e., bacteria and archaea) in bulk samples, and in addition, in detail on a millimeter scale in one microbial mat and in one evaporite. Archaea were more abundant than bacteria. Euryarchaeota was one of the most abundant phyla in all samples, and particularly dominant (97% of total diversity) in the most lithified ecosystem, the evaporite. Most of the euryarchaeal OTUs could be assigned to the class Halobacteria or anaerobic and methanogenic archaea. Planctomycetes potentially also play a key role in mats and rhizome-associated concretions, notably the aerobic organoheterotroph members of the class Phycisphaerae. In addition to cyanobacteria, members of Chromatiales and possibly the candidate family Chlorotrichaceae contributed to photosynthetic carbon fixation. Other abundant uncultured taxa such as the candidate division MSBL1, the uncultured MBGB, and the phylum Acetothermia potentially play an important metabolic role in these ecosystems. Lithifying microbial mats contained calcium carbonate precipitates, whereas endoevoporites consisted of gypsum, and halite. Biogeochemical measurements revealed that based on depth profiles of O2 and sulfide, metabolic activities were much higher in the non-lithifying mat (peaking in the least lithified systems) than in lithifying mats with the lowest activity in endoevaporites. This trend in decreasing microbial activity reflects the increase in salinity, which may play an important role in the biodiversity. PMID:27597845

  8. Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile.

    Science.gov (United States)

    Fernandez, Ana B; Rasuk, Maria C; Visscher, Pieter T; Contreras, Manuel; Novoa, Fernando; Poire, Daniel G; Patterson, Molly M; Ventosa, Antonio; Farias, Maria E

    2016-01-01

    We combined nucleic acid-based molecular methods, biogeochemical measurements, and physicochemical characteristics to investigate microbial sedimentary ecosystems of Laguna Tebenquiche, Atacama Desert, Chile. Molecular diversity, and biogeochemistry of hypersaline microbial mats, rhizome-associated concretions, and an endoevaporite were compared with: The V4 hypervariable region of the 16S rRNA gene was amplified by pyrosequencing to analyze the total microbial diversity (i.e., bacteria and archaea) in bulk samples, and in addition, in detail on a millimeter scale in one microbial mat and in one evaporite. Archaea were more abundant than bacteria. Euryarchaeota was one of the most abundant phyla in all samples, and particularly dominant (97% of total diversity) in the most lithified ecosystem, the evaporite. Most of the euryarchaeal OTUs could be assigned to the class Halobacteria or anaerobic and methanogenic archaea. Planctomycetes potentially also play a key role in mats and rhizome-associated concretions, notably the aerobic organoheterotroph members of the class Phycisphaerae. In addition to cyanobacteria, members of Chromatiales and possibly the candidate family Chlorotrichaceae contributed to photosynthetic carbon fixation. Other abundant uncultured taxa such as the candidate division MSBL1, the uncultured MBGB, and the phylum Acetothermia potentially play an important metabolic role in these ecosystems. Lithifying microbial mats contained calcium carbonate precipitates, whereas endoevoporites consisted of gypsum, and halite. Biogeochemical measurements revealed that based on depth profiles of O2 and sulfide, metabolic activities were much higher in the non-lithifying mat (peaking in the least lithified systems) than in lithifying mats with the lowest activity in endoevaporites. This trend in decreasing microbial activity reflects the increase in salinity, which may play an important role in the biodiversity. PMID:27597845

  9. Survey Strategy Optimization for the Atacama Cosmology Telescope

    Science.gov (United States)

    De Bernardis, F.; Stevens, J. R.; Hasselfield, M.; Alonso, D.; Bond, J. R.; Calabrese, E.; Choi, S. K.; Crowley, K. T.; Devlin, M.; Wollack, E. J.

    2016-01-01

    In recent years there have been significant improvements in the sensitivity and the angular resolution of the instruments dedicated to the observation of the Cosmic Microwave Background (CMB). ACTPol is the first polarization receiver for the Atacama Cosmology Telescope (ACT) and is observing the CMB sky with arcmin resolution over approximately 2000 square degrees. Its upgrade, Advanced ACTPol (AdvACT), will observe the CMB in five frequency bands and over a larger area of the sky. We describe the optimization and implementation of the ACTPol and AdvACT surveys. The selection of the observed fields is driven mainly by the science goals, that is, small angular scale CMB measurements, B-mode measurements and cross-correlation studies. For the ACTPol survey we have observed patches of the southern galactic sky with low galactic foreground emissions which were also chosen to maximize the overlap with several galaxy surveys to allow unique cross-correlation studies. A wider field in the northern galactic cap ensured significant additional overlap with the BOSS spectroscopic survey. The exact shapes and footprints of the fields were optimized to achieve uniform coverage and to obtain cross-linked maps by observing the fields with different scan directions. We have maximized the efficiency of the survey by implementing a close to 24-hour observing strategy, switching between daytime and nighttime observing plans and minimizing the telescope idle time. We describe the challenges represented by the survey optimization for the significantly wider area observed by AdvACT, which will observe roughly half of the low-foreground sky. The survey strategies described here may prove useful for planning future ground-based CMB surveys, such as the Simons Observatory and CMB Stage IV surveys.

  10. Solar Observations with the Atacama Large Millimeter/submillimeter Array

    Science.gov (United States)

    Wedemeyer, Sven

    2015-08-01

    The interferometric Atacama Large Millimeter/submillimeter Array (ALMA) has already demonstrated its impressive capabilities by observing a large variety of targets ranging from protoplanetary disks to galactic nuclei. ALMA is also capable of observing the Sun and has been used for five solar test campaigns so far. The technically challenging solar observing modes are currently under development and regular observations are expected to begin in late 2016.ALMA consists of 66 antennas located in the Chilean Andes at an altitude of 5000 m and is a true leap forward in terms of spatial resolution at millimeter wavelengths. The resolution of reconstructed interferometric images of the Sun is anticipated to be close to what current optical solar telescopes can achieve. In combination with the high temporal and spectral resolution, these new capabilities open up new parameter spaces for solar millimeter observations.The solar radiation at wavelengths observed by ALMA originates from the chromosphere, where the height of the sampled layer increases with selected wavelength. The continuum intensity is linearly correlated to the local gas temperature in the probed layer, which makes ALMA essentially a linear thermometer. During flares, ALMA can detect additional non-thermal emission contributions. Measurements of the polarization state facilitate the valuable determination of the chromospheric magnetic field. In addition, spectrally resolved observations of radio recombination and molecular lines may yield great diagnostic potential, which has yet to be investigated and developed.Many different scientific applications for a large range of targets from quiet Sun to active regions and prominences are possible, ranging from ultra-high cadence wave studies to flare observations. ALMA, in particular in combination with other ground-based and space-borne instruments, will certainly lead to fascinating new findings, which will advance our understanding of the atmosphere of our Sun

  11. THE ATACAMA COSMOLOGY TELESCOPE: DATA CHARACTERIZATION AND MAPMAKING

    Energy Technology Data Exchange (ETDEWEB)

    Duenner, Rolando; Aguirre, Paula; Barrientos, L. Felipe [Departamento de Astronomia y Astrofisica, Facultad de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Hasselfield, Matthew; Amiri, Mandana; Battistelli, Elia S.; Burger, Bryce [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Marriage, Tobias A.; Acquaviva, Viviana; Das, Sudeep [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Sievers, Jon; Appel, John William [Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States); Addison, Graeme E.; Calabrese, Erminia [Department of Astrophysics, Oxford University, Oxford OX1 3RH (United Kingdom); Ade, Peter A. R. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Bond, J. Richard [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Brown, Ben [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Chervenak, Jay [Code 553/665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Devlin, Mark J.; Dicker, Simon R. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); and others

    2013-01-01

    We present a description of the data reduction and mapmaking pipeline used for the 2008 observing season of the Atacama Cosmology Telescope (ACT). The data presented here at 148 GHz represent 12% of the 90 TB collected by ACT from 2007 to 2010. In 2008 we observed for 136 days, producing a total of 1423 hr of data (11 TB for the 148 GHz band only), with a daily average of 10.5 hr of observation. From these, 1085 hr were devoted to an 850 deg{sup 2} stripe (11.2 hr by 9. Degree-Sign 1) centered on a declination of -52. Degree-Sign 7, while 175 hr were devoted to a 280 deg{sup 2} stripe (4.5 hr by 4. Degree-Sign 8) centered at the celestial equator. The remaining 163 hr correspond to calibration runs. We discuss sources of statistical and systematic noise, calibration, telescope pointing, and data selection. For the 148 GHz band, out of 1260 survey hours and 1024 detectors in the array, 816 hr and 593 effective detectors remain after data selection, yielding a 38% survey efficiency. The total sensitivity in 2008, determined from the noise level between 5 Hz and 20 Hz in the time-ordered data stream (TOD), is 32 {mu}K{radical}s in cosmic microwave background units. Atmospheric brightness fluctuations constitute the main contaminant in the data and dominate the detector noise covariance at low frequencies in the TOD. The maps were made by solving the least-squares problem using the Preconditioned Conjugate Gradient method, incorporating the details of the detector and noise correlations. Simulations, as well as cross-correlations with Wilkinson Microwave Anisotropy Probe sky maps on large angular scales, reveal that our maps are unbiased at multipoles l > 300. This paper accompanies the public release of the 148 GHz southern stripe maps from 2008. The techniques described here will be applied to future maps and data releases.

  12. Mirror illumination and spillover measurements of the Atacama Cosmology Telescope

    Science.gov (United States)

    Gallardo, Patricio; Dünner, Rolando; Wollack, Edward; Henriquez, Fernando; Jerez-Hanckes, Carlos

    2012-09-01

    The Atacama Cosmology Telescope (ACT) is a 6 m telescope designed to map the Cosmic Microwave Background (CMB) simultaneously at 145 GHz, 220 GHz and 280GHz. The receiver in ACT, the Millimeter Bolometer Array Camera, features 1000 TES bolometers in each band. The detector performance depends critically on the total optical loading, requiring the spillover contributions from the optics to be minimal. This inspired the use of a cold Lyot stop to limit the illumination of the primary and the use of guard rings surrounding the primary and secondary reflectors. Here, we present a direct measurement of the illumination aperture for both reflectors and of the attenuation level outside the main optical path. We used a 145 GHz, 1mW source and a chopper wheel to produce a time-varying signal with a broad beam profile. We sampled the response of the camera for different locations of the source, placed in front and beside the primary and secondary mirrors. The aperture of the primary was measured to be 5.72 ± 0.17m in diameter (95 ± 3% of its geometrical size), while the aperture of the secondary yielded 2 ± 0.12m in diameter. Both apertures are consistent with the optical design. Comparing to previous measurements of the beam solid angle from planet observations, we estimate an optical efficiency of 72.3 ± 4.8%. We found that the attenuation outside the primary aperture was -16 ± 2 dB, which is below the theoretical expectations, and -22 ± 1 dB outside the secondary aperture, which is consistent with simulations. These results motivated the extension of the baffles surrounding the secondary mirror, with the following reduction in detector optical loading from 2.24pW to 1.88 pW.

  13. ANIR : Atacama Near-Infrared Camera for the 1.0-m miniTAO Telescope

    OpenAIRE

    Konishi, Masahiro; Motohara, Kentaro; Tateuchi, Ken; TAKAHASHI, Hidenori; Kitagawa, Yutaro; Kato, Natsuko; Sako, Shigeyuki; Uchimoto, Yuka K.; Toshikawa, Koji; Ohsawa, Ryou; Yamamuro, Tomoyasu; Asano, Kentaro; Ita, Yoshifusa; Kamizuka, Takafumi; Komugi, Shinya

    2015-01-01

    We have developed a near-infrared camera called ANIR (Atacama Near-InfraRed camera) for the University of Tokyo Atacama Observatory 1.0m telescope (miniTAO) installed at the summit of Cerro Chajnantor (5640 m above sea level) in northern Chile. The camera provides a field of view of 5'.1 $\\times$ 5'.1 with a spatial resolution of 0".298 /pixel in the wavelength range of 0.95 to 2.4 $\\mu$m. Taking advantage of the dry site, the camera is capable of hydrogen Paschen-$\\alpha$ (Pa$\\alpha$, $\\lamb...

  14. Mate desertion in the snail kite

    Science.gov (United States)

    Beissinger, S.R.; Snyder, N.F.R.

    1988-01-01

    Mate desertion during the breeding cycle was documented at 28 of 36 (78%) snail kite, Rostrhamus sociabilis nests in Florida between 1979 and 1983. Offspring mortality occurred at only one deserted nest, however. Parents that were deserted by their mates continued to care for their young until independence (3?5 additional weeks) and provided snails at a rate similar to that of both parents combined before desertion. Males and females deserted with nearly equal frequency, except in 1982 when more females deserted. No desertion occurred during drought years, whereas desertion occurred at nearly every nest during favourable conditions. The occurrence of mate desertion was generally related to indirect measures of snail abundance: foraging range, snail delivery rates to the young and growth rates. Small broods were deserted more frequently by females than by males and tended to be deserted earlier than large ones. After desertion, deserters had the opportunity to re-mate and nest again since breeding seasons were commonly lengthy, but whether they did so was impossible to determine conclusively in most cases. The deserted bird sometimes incurred increased energetic costs and lost breeding opportunities during periods of monoparental care.

  15. Sea Breezes over the Red Sea: Affect of topography and interaction with Desert Convective Boundary Layer

    Science.gov (United States)

    Khan, Basit A.; Stenchikov, Georgiy; Abualnaja, Yasser

    2014-05-01

    Thermodynamic structure of sea-breeze, its interaction with coastal mountains, desert plateau and desert convective boundary layer have been investigated in the middle region of the Red Sea around 25°N, at the Western coast of Saudi Arabia. Sea and land breeze is a common meteorological phenomenon in most of the coastal regions around the world. Sea-Breeze effects the local meteorology and cause changes in wind speed, direction, cloud cover and sometimes precipitation. The occurrence of sea-breeze, its intensity and landward propagation are important for wind energy resource assessment, load forecasting for existing wind farms, air pollution, marine and aviation applications. The thermally induced mesoscale circulation of sea breeze modifies the desert Planetary Boundary Layer (PBL) by forming Convective Internal Boundary Layer (CIBL), and propagates inland as a density current. The leading edge of the denser marine air rapidly moves inland undercutting the hot and dry desert air mass. The warm air lifts up along the frontal boundary and if contains enough moisture a band of clouds is formed along the sea breeze front (SBF). This study focuses on the thermodynamic structure of sea-breeze as it propagates over coastal rocky mountain range of Al-Sarawat, east of the Red Sea coast, and the desert plateau across the mountain range. Additional effects of topographical gaps such as Tokar gap on the dynamics of sea-land breezes have also been discussed. Interaction of SBF with the desert convective boundary layer provide extra lifting that could further enhance the convective instability along the frontal boundary. This study provides a detailed analysis of the thermodynamics of interaction of the SBF and convective internal boundary layer over the desert. Observational data from a buoy and meteorological stations have been utilized while The Advanced Research WRF (ARW) modeling system has been employed in real and 2D idealized configuration.

  16. Desert and desertification in Iran

    Science.gov (United States)

    Bahrami, M.

    2009-04-01

    One of the greatest environmental concerns in Iran as in other arid and semiarid countries is the transformation of once productive, or marginally productive, land to deteriorated land and soil unable to support plants and animals. Because the land becomes barren and dry, the process is described as desertification, which occurs as a sequence of events. The area of deserts in Iran is about 340,000 Km2 (less than one fifth of its total area), of which 100,000 Km2 is being used for some cultivation, 120,000 Km2 is subjected to moving sands about 40 % of which is active sand dunes. Most of features and processes usual in world famous deserts are also observed in Iran: low precipitation, high evaporation, poor or lack of vegetation, saline and alkaline soils, low population and small and sparse oases. The deserts of Iran are generally classified in the subtropical, warm, arid and semiarid group, but the effect and presence of some geographical and geoclimatical factors such as height, vicinity to Indian Ocean and so on do some changes in climatic conditions and geographical features causing some local and regional differences in them. Geographically, two groups of deserts have been known in Iran: (1) Coastal deserts which, like a ribbon with variable width, stretch from extreme southeast to extreme southwest, at the north parts of Oman Sea and Persian Gulf. One important feature of these deserts is relatively high humidity which differentiates them from other deserts. This causes an increase in vegetation coverage and hence a decrease in eolian erosion and also a dominance of chemical weathering to that of physical. (2) internal deserts, which rest in central, eastern and southeastern plateau of the country and in independent and semi dependent depressions. This situation, which is due to the surrounding high mountains, blocks humidity entry and causes the aridity of these deserts. Wind as a dominant process in the area causes deflated features such as Reg (desert

  17. Impact and monitoring of dust storms in Taklimakan desert

    Science.gov (United States)

    Feng, G. G.; Li, X.; Zheng, Z.

    2012-12-01

    determined that the horizontal dust flux was 0.6 to 4.3 kg/m. Dust clouds are formed when the friction from high surface wind speeds (>6 m/s) lifts loose dust particles into the atmospheric boundary layer or above. Analysis shows that a dust storm in the Taklimakan desert on April 23th produced a huge atmospheric dust cloud, it was transported across the Pacific Ocean to reach the West Coast of North America 12 days later, corresponding to 6 m/s average transport speed. The observations in the Pacific Coast indicated that aerosol concentrations were elevated which resulted in Air Quality Index (AQI) to the yellow moderate category.

  18. Recommended Cross-Desert Driving Route

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Beijing - Duolun - Dalai Nur- Hexigten Banner -Saihanba - Weichang - Luanping - Miyun - Beijing. Along this 1,600-kilometer route is a 150-kin section(between Duolun and Darhan) of desert with no surfaced road - a paradise for desert drivers.

  19. Stone structures in the Syrian Desert

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    An arid land, known as the Syrian Desert, is covering a large part of the Middle East. In the past, this harsh environment, characterized by huge lava fields, the "harraat", was considered as a barrier between Levant and Mesopotamia. When we observe this desert from space, we discover that it is crossed by some stone structures, the "desert kites", which were the Neolithic traps for the game. Several stone circles are visible too, as many Stonehenge sites dispersed in the desert landscape.

  20. Phytoremediation for Oily Desert Soils

    Science.gov (United States)

    Radwan, Samir

    This chapter deals with strategies for cleaning oily desert soils through rhizosphere technology. Bioremediation involves two major approaches; seeding with suitable microorganisms and fertilization with microbial growth enhancing materials. Raising suitable crops in oil-polluted desert soils fulfills both objectives. The rhizosphere of many legume and non-legume plants is richer in oil-utilizing micro-organisms than non-vegetated soils. Furthermore, these rhizospheres also harbour symbiotic and asymbiotic nitrogen-fixing bacteria, and are rich in simple organic compounds exuded by plant roots. Those exudates are excellent nutrients for oil-utilizing microorganisms. Since many rhizospheric bacteria have the combined activities of hydrocarbon-utilization and nitrogen fixation, phytoremediation provides a feasible and environmentally friendly biotechnology for cleaning oil-polluted soils, especially nitrogen-poor desert soils.

  1. Women in the Gobi Desert

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    THE plane flew for about an hour,transporting me from Beijing to adeserted land,the Gobi desert,where sits the China Arms Testing &Training Target Field.For about 40 years,thousands of scientists and technicianshave made hundreds of greatachievements in the history of Chinesearms testing;among them are a lot ofunusual women making their own quietcontributions.

  2. On a Crowded Desert Island.

    Science.gov (United States)

    Rothstein, Samuel

    1989-01-01

    Suggests reference sources most appropriate for a desert island. In addition to "Robinson Crusoe" (Daniel Defoe) and a reference guide to the literature of travel, the list includes basic books on reference work, guides to reference sources, journals, an almanac, encyclopedias, a guide to English usage, and a book of quotations. (14 references)…

  3. SSALMON - The Solar Simulations for the Atacama Large Millimeter Observatory Network

    CERN Document Server

    Wedemeyera, S; Brajsa, R; Barta, M; Hudson, H; Fleishman, G; Loukitcheva, M; Fleck, B; Kontar, E; De Pontieu, B; Tiwari, S; Kato, Y; Soler, R; Yagoubov, P; Black, J H; Antolin, P; Gunar, S; Labrosse, N; Benz, A O; Nindos, A; Steffen, M; Scullion, E; Doyle, J G; Zaqarashvili, T; Hanslmeier, A; Nakariakov, V M; Heinzel, P; Ayres, T; Karlicky, M

    2015-01-01

    The Solar Simulations for the Atacama Large Millimeter Observatory Network (SSALMON) was initiated in 2014 in connection with two ALMA development studies. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new tool, which can also observe the Sun at high spatial, temporal, and spectral resolution. The international SSALMONetwork aims at coordinating the further development of solar observing modes for ALMA and at promoting scientific opportunities for solar physics with particular focus on numerical simulations, which can provide important constraints for the observing modes and can aid the interpretation of future observations. The radiation detected by ALMA originates mostly in the solar chromosphere - a complex and dynamic layer between the photosphere and corona, which plays an important role in the transport of energy and matter and the heating of the outer layers of the solar atmosphere. Potential targets include active regions, prominences, quiet Sun regions, flares. Here, we give a...

  4. The Atacama Cosmology Telescope: Beam Measurements and the Microwave Brightness Temperatures of Uranus and Saturn

    OpenAIRE

    Hasselfield, Matthew; Moodley, Kavilan; Bond, J. Richard; Das, Sudeep; Devlin, Mark J.; Dunkley, Joanna; Dünner, Rolando; Fowler, Joseph W.; Gallardo, Patricio; Gralla, Megan B.; Hajian, Amir; Halpern, Mark; Hincks, Adam D.; Marriage, Tobias A.; Marsden, Danica

    2013-01-01

    We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilo-pixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty, to derive window functions relevant for angular power spect...

  5. María Elena: el fin de una experiencia urbana: Un estudio de caso en el desierto de Atacama, Chile

    Directory of Open Access Journals (Sweden)

    JUAN CARLOS RODRÍGUEZ TORRENT

    2009-08-01

    Full Text Available En el presente trabajo se plantea la relación entre la ciudad salitrera de María Elena (II Región, diseñada de acuerdo a propuestas utópicas en un territorio privado, y el cambio de las relaciones laborales entre la Compañía SQM y los trabajadores a partir del predominio de un nuevo modelo de acumulación cuyos ejes están dados por la competitividad, la producción de calidad y la globalización. La ciudad fue creada para que hombres y mujeres construyeran sus proyectos de vida en medio del Desierto de Atacama, ofreciéndoles todas las garantías y la infraestructura para que ello fuese así en los marcos de una política de pleno empleo, de modo de contener a la población en un medio inhóspito, cumplir los objetivos productivos y fortalecer una identidad coherente y cohesionada, lo que a partir de nuevas decisiones estratégicas es substituido por un modelo de flexibilidad laboral, lo que anula su definición primigenia y el interés colectivo para comenzar a dar paso a un campamento minero.In this paper we look into the relationship between the nitrate town of Maria Elena (in Region II - designed on Utopian principals as a private project - and the changing labor relations between the SQM Company and the workers as a result of the predominance of a new accumulation model guided by competitiveness, quality production and globalization. The town was created so that men and women could establish their livelihoods in the Atacama Desert, with guarantees and infrastructure based on a full employment policy. This was in order to anchor the population in this inhospitable environment, to meet production objectives and to strengthen a coherent and cohesive identity. New strategic decisions led to this model being replaced by one based on labour flexibilization, deleting its original intention and collective interest to give way to a mining camp.

  6. Oral health in prehistoric San Pedro de Atacama oases, Northern Chile.

    Science.gov (United States)

    Oliveira, R E; Neves, W A

    2015-12-01

    After almost 2000 years of local development, including limited trading with neighboring ethnic groups, the societies that occupied the oases of San Pedro de Atacama, Northern Chile, became part of the trade web of the Tiwanaku empire, between 500 and 1000 CE. Archaeological evidence tends to support the idea that the period under the influence of the altiplano (high plane) empire was very affluent. Here we investigate the possibility that this affluence had a positive impact on the health status of the Atacameneans, using the oral health as an indirect indicator of quality of life. Dental decay, dental abscess, dental wear, linear enamel hypoplasia, periodontal disease and dental calculus were analyzed on 371 skeletons from 12 sites from San Pedro de Atacama oases. We believe that if, indeed, there were better biological conditions during the altiplano influence, this could have been caused by the access to a more diversified food intake promoted by the intensification of the trading network established by Tiwanaku in the central-south Andes, of which San Pedro de Atacama became an important node.

  7. US west coast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Aerial surveys are conducted along the US west coast to determine distribution and abundance of endangered leatherback turtles (Dermochelys coriacea), loggerhead...

  8. Network topology of the desert rose

    Science.gov (United States)

    Hope, Sigmund; Kundu, Sumanta; Roy, Chandreyee; Manna, Subhrangshu; Hansen, Alex

    2015-09-01

    Desert roses are gypsum crystals that consist of intersecting disks. We determine their geometrical structure using computer assisted tomography. By mapping the geometrical structure onto a graph, the topology of the desert rose is analyzed and compared to a model based on diffusion limited aggregation. By comparing the topology, we find that the model gets a number of the features of the real desert rose right, whereas others do not fit so well.

  9. Network topology of the desert rose

    Directory of Open Access Journals (Sweden)

    Sigmund Mongstad Hope

    2015-09-01

    Full Text Available Desert roses are gypsum crystals that consist of intersecting disks. We determine their geometrical structure using computer assisted tomography. By mapping the geometrical structure onto a graph, the topology of the desert rose is analyzed and compared to a model based on diffusion limited aggregation. By comparing the topology, we find that the model gets a number of the features of the real desert rose right, whereas others do not fit so well.

  10. The biological factors influence on the conversion of mineral components of Extremely Arid Desert Soils (Kazakhstan)

    Science.gov (United States)

    Kutovaya, Olga; Vasilenko, Elena; Lebedeva, Marina; Tkhakakhova, Azida

    2013-04-01

    Extremely arid soils of stony deserts (hamadas) along the southern periphery of the Ili Depression are considered to be analogous to extremely arid soils of Mongolia, also named as "ultra-arid primitive gray-brown soils." In general, the morphology of extremely arid soils of hamadas in the Ili Depression is similar to that of the soils of stony deserts in other parts of the world, including the Gobi, Atacama, and Tarim deserts. The diagnostics of the active communities of microorganisms were performed according to the method of Rybalkina-Kononenko. The exact identification of the living forms of microorganisms to the species level is not always possible with the use of this method. However, it allows us to study the physiological role of the microorganisms and their ecological functions, including the relationships with the soil matrix and other organisms. In particular, it is possible to estimate the contribution of the microorganisms to the transformation of mineral soil components. The obtained materials allow us to conclude that the extremely arid desert soils are characterized by the very high biological activity during short periods of the increased soil moistening after rare and strong rains. The diversity of living forms is very considerable; both prokaryotes (cyanobacteria, actinomycetes, and iron bacteria) and protists (green algae, diatoms, and dinoflagellates) are developed in the soil. Thus, during a short period after the rains, these microorganisms pass from the stage of anabiosis to the stage of active growth and reproduction. Then, upon drying of the soil, the biotic activity of the soil slows down and, finally, terminates. The organisms remain in the state of anabiosis until the next rain. During the period of active growth, the microorganisms compose a specific consortium of different species and exert a profound impact on the soil properties. They participate in the transformation of the soil minerals with the formation of amorphous substances

  11. Non-thermal WIMPs as "Dark Radiation" in Light of ATACAMA, SPT, WMAP9 and Planck

    CERN Document Server

    Kelso, Chris; Queiroz, Farinaldo S

    2013-01-01

    The Planck and WMAP9 satellites, as well as the ATACAMA and South Pole telescopes, have recently presented results on the angular power spectrum of the comic microwave background. Data tentatively point to the existence of an extra radiation component in the early universe. Here, we show that this extra component can be mimicked by ordinary WIMP dark matter particles whose majority is cold, but with a small fraction being non-thermally produced in a relativistic state. We present a few example theories where this scenario is explicitly realized, and explore the relevant parameter space consistent with BBN, CMB and Structure Formation bounds.

  12. Rural childhoods in Egypt's desert lands

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine

    ’s new roles impact upon the children’s lives. The social contexts shaping the desert childhoods are in some ways more similar to contexts in ‘developed’ countries than in other parts of rural Egypt. The paper ends up by contrasting ideas of rural childhoods in Egypt with those found in ‘developed......Based on fieldwork in Egypt’s desert lands, this paper discusses rural childhoods in an area experiencing rapid social and cultural change. Since 1987, the Egyptian Government has made new villages in the desert as a means to increase agricultural production and solving problems of unemployment....... Many settlers move to the Mubarak villages in order to give their children a good start in life. The desert villages are associated with a type of ‘rural idyll’. The process of settling in the desert impacts upon the children’s possible pathways to adulthood and their identities and social...

  13. Cost of m{sup 2} installed of hot water to pave in cities of the desert of Atacama; Costo del m{sup 2} instalado de agua caliente solar en ciudades del desierto de Atacama

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, W. W.; Galleguillos, V. R.; Echevarria, A. J.

    2008-07-01

    In this work were registered the domiciliary solar hot water of flat plate collectors for innovating projects that rationalize their use in Antofagasta, 300000 habitants; 23,5 degree S: 70.1 degree W. Average solar radiation in the city is about of 20 MJ/m{sup 2}fay. The medium temperature of water by day on the city is 17 degree centigrade. Annual average of the relative humidity is approximately 70%m the precipitations in the city are extremely low about 1 mm and the sea breeze is around 2.5 m/s, which comes from of the ocean pacific in SW direction. Our study informs that to heat 100 liters of water up to 40 degree centigrade, it is necessary 1 m{sup 2} of solar collector to US$ 700, the m{sup 2} installed. The city has 61 of these facilities in hospitals, school, high school and housings. Our study informs of a total of 700 m{sup 2} of solar collector and 33400 available of hot water liters. (Author)

  14. The Atacama Cosmology Telescope: The LABOCA/ACT Survey of Clusters at All Redshifts

    CERN Document Server

    Lindner, Robert R; Baker, Andrew J; Bond, J Richard; Crichton, Devin; Devlin, Mark J; Essinger-Hileman, Thomas; Hilton, Matt; Hincks, Adam D; Huffenberger, Kevin M; Hughes, John P; Infante, Leopoldo; Lima, Marcos; Marriage, Tobias A; Menanteau, Felipe; Niemack, Michael D; Page, Lyman A; Schmitt, Benjamin L; Sehgal, Neelima; Sievers, J L; Sifón, Cristóbal; Staggs, Suzanne T; Swetz, Daniel; Weiß, Axel; Wollack, Edward J

    2014-01-01

    We present a multi-wavelength analysis of eleven Sunyaev Zel'dovich effect (SZE)-selected galaxy clusters (ten with new data) from the Atacama Cosmology Telescope (ACT) southern survey. We have obtained new imaging from the Large APEX Bolometer Camera (345GHz; LABOCA) on the Atacama Pathfinder EXperiment (APEX) telescope, the Australia Telescope Compact Array (2.1GHz; ATCA), and the Spectral and Photometric Imaging Receiver (250, 350, and $500\\,\\rm\\mu m$; SPIRE) on the Herschel Space Observatory. Spatially-resolved 345GHz SZE increments with integrated S/N > 5 are found in six clusters. We compute 2.1GHz number counts as a function of cluster-centric radius and find significant enhancements in the counts of bright sources at projected radii $\\theta < \\theta_{2500}$. By extrapolating in frequency, we predict that the combined signals from 2.1GHz-selected radio sources and 345GHz-selected SMGs contaminate the 148GHz SZE decrement signal by ~5% and the 345GHz SZE increment by ~18%. After removing radio source...

  15. ANIR : Atacama Near-Infrared Camera for the 1.0-m miniTAO Telescope

    CERN Document Server

    Konishi, Masahiro; Tateuchi, Ken; Takahashi, Hidenori; Kitagawa, Yutaro; Kato, Natsuko; Sako, Shigeyuki; Uchimoto, Yuka K; Toshikawa, Koji; Ohsawa, Ryou; Yamamuro, Tomoyasu; Asano, Kentaro; Ita, Yoshifusa; Kamizuka, Takafumi; Komugi, Shinya; Koshida, Shintaro; Manabe, Sho; Matsunaga, Noriyuki; Minezaki, Takeo; Morokuma, Tomoki; Nakashima, Asami; Takagi, Toshinobu; Tanabé, Toshihiko; Uchiyama, Mizuho; Aoki, Tsutomu; Doi, Mamoru; Handa, Toshihiro; Kato, Daisuke; Kawara, Kimiaki; Kohno, Kotaro; Miyata, Takashi; Nakamura, Tomohiko; Okada, Kazushi; Soyano, Takao; Tamura, Yoichi; Tanaka, Masuo; Tarusawa, Ken'ichi; Yoshii, Yuzuru

    2015-01-01

    We have developed a near-infrared camera called ANIR (Atacama Near-InfraRed camera) for the University of Tokyo Atacama Observatory 1.0m telescope (miniTAO) installed at the summit of Cerro Chajnantor (5640 m above sea level) in northern Chile. The camera provides a field of view of 5'.1 $\\times$ 5'.1 with a spatial resolution of 0".298 /pixel in the wavelength range of 0.95 to 2.4 $\\mu$m. Taking advantage of the dry site, the camera is capable of hydrogen Paschen-$\\alpha$ (Pa$\\alpha$, $\\lambda=$1.8751 $\\mu$m in air) narrow-band imaging observations, at which wavelength ground-based observations have been quite difficult due to deep atmospheric absorption mainly from water vapor. We have been successfully obtaining Pa$\\alpha$ images of Galactic objects and nearby galaxies since the first-light observation in 2009 with ANIR. The throughputs at the narrow-band filters ($N1875$, $N191$) including the atmospheric absorption show larger dispersion (~10%) than those at broad-band filters (a few %), indicating that ...

  16. Manado: A Developing Coast

    NARCIS (Netherlands)

    Tenthof van Noorden, C.; Vermeij, D.; Van Zuijlen, J.; Zeelenberg, W.

    2013-01-01

    Manado, the capital city of North Sulawesi in Indonesia, is rapidly developing. The last years Manado has been extending into the sea, which changed the hydraulics and morphology of Manado Bay. This had negative effects on the currents, inducing erosion along the coast. Also Manado has problems with

  17. Deserts

    DEFF Research Database (Denmark)

    Graulund, Rune

    2016-01-01

    , comic sketches and lyrical reveries; travel writing is now a crucial focus for discussion across many subjects within the humanities and social sciences. An ideal starting point for beginners, but also offering new perspectives for those familiar with the field, The Routledge Companion to Travel Writing...

  18. Diversidad y patrones de distribución geográfica de insectos coleópteros en ecosistemas desérticos de la región de Antofagasta, Chile Diversity and geographic distribution patterns of coleopteran insects in desert ecosystems of the Antofagasta region, Chile

    Directory of Open Access Journals (Sweden)

    VIVIANE JEREZ

    2000-03-01

    their distribution ranges are given. The possible biogeographic relationships which could exist between the different described ecosystems of the region were analyzed. In this analysis, a coleopteran species inventory was elaborated based upon the literature, collected material from museums, and observations from field work. The spatial distribution of the taxa was established in relation to 11 described ecosystems for the Region and the endemic areas were determined using a biogeographic parsimony analysis. The taxonomic composition of Coleoptera is comprised of 21 families, 86 genera, and 167 species, with Tenebrionidae as the most diverse having 23 genera and 78 species. The Subdesertic steppe of the puna (57 sp., Coastal desert of Tocopilla (50 sp., Desert of Atacama saltflat (35 sp., Coastal desert of Taltal (32 sp., Aluvian Desert (22 sp., and the Shrubery steppe (17 sp. are the ecosystems that present the most diversification. However, the Coastal desert of Tocopilla (72%, Coastal desert of Taltal (62.5%, Subdesertic steppe of the puna (55.8%, Desert of Atacama saltflat (51.4%, Shrubery steppe (47%, and the Aluvian desert (36.3% have the highest percentages of endemism. Three areas of endemism are defined for the Region of Antofagasta, which correspond to three ecosystems distributed in an altitudinal gradient: Coastal desert, Aluvian desert, and Tropical zone

  19. The Mojave Desert: A Martian Analog Site for Future Astrobiology Themed Missions

    Science.gov (United States)

    Salas, E.; Abbey, W.; Bhartia, R.; Beegle, L. W.

    2011-01-01

    Astrobiological interest in Mars is highlighted by evidence that Mars was once warm enough to have liquid water present on its surface long enough to create geologic formations that could only exist in the presense of extended fluvial periods. These periods existed at the same time life on Earth arose. If life began on Mars as well during this period, it is reasonable to assume it may have adapted to the subsurface as environments at the surface changed into the inhospitable state we find today. If the next series of Mars missions (Mars Science Laboratory, the ExoMars Trace Gas Orbiter proposed for launch in 2016, and potential near surface sample return) fail to discover either extinct or extant life on Mars, a subsurface mission would be necessary to attempt to "close the book" on the existence of martian life. Mars is much colder and drier than Earth, with a very low pressure CO2 environment and no obvious habitats. Terrestrial regions with limited precipitation, and hence reduced active biota, are some of the best martian low to mid latitude analogs to be found on Earth, be they the Antarctic dry valleys, the Atacama or Mojave Deserts. The Mojave Desert/Death Valley region is considered a Mars analog site by the Terrestrial Analogs Panel of the NSF-sponsored decadal survey; a field guide was even developed and a workshop was held on its applicability as a Mars analog. This region has received a great deal of attention due to its accessibility and the variety of landforms and processes observed relevant to martian studies.

  20. Modelling the spectral response of the desert tree Prosopis tamarugo to water stress

    Science.gov (United States)

    Chávez, R. O.; Clevers, J. G. P. W.; Herold, M.; Ortiz, M.; Acevedo, E.

    2013-04-01

    In this paper, we carried out a laboratory experiment to study changes in canopy reflectance of Tamarugo plants under controlled water stress. Tamarugo (Prosopis tamarugo Phil.) is an endemic and endangered tree species adapted to the hyper-arid conditions of the Atacama Desert, Northern Chile. Observed variation in reflectance during the day (due to leaf movements) as well as changes over the experimental period (due to water stress) were successfully modelled by using the Soil-Leaf-Canopy (SLC) radiative transfer model. Empirical canopy reflectance changes were mostly explained by the parameters leaf area index (LAI), leaf inclination distribution function (LIDF) and equivalent water thickness (EWT) as shown by the SLC simulations. Diurnal leaf movements observed in Tamarugo plants (as adaptation to decrease direct solar irradiation at the hottest time of the day) had an important effect on canopy reflectance and were explained by the LIDF parameter. The results suggest that remote sensing based assessment of this desert tree should consider LAI and canopy water content (CWC) as water stress indicators. Consequently, we tested fifteen different vegetation indices and spectral absorption features proposed in literature for detecting changes of LAI and CWC, considering the effect of LIDF variations. A sensitivity analysis was carried out using SLC simulations with a broad range of LAI, LIDF and EWT values. The Water Index was the most sensitive remote sensing feature for estimating CWC for values less than 0.036 g/cm2, while the area under the curve for the spectral range 910-1070 nm was most sensitive for values higher than 0.036 g/cm2. The red-edge chlorophyll index (CIred-edge) performed the best for estimating LAI. Diurnal leaf movements had an effect on all remote sensing features tested, particularly on those for detecting changes in CWC.

  1. El Niño southern oscillation and its effect on fog oases along the Peruvian and Chilean coastal deserts

    OpenAIRE

    Manrique Paredes, Rosa Soledad

    2011-01-01

    Fog oases, locally named Lomas, are distributed in a fragmented way along the western coast of Chile and Peru (South America) between ~6°S and 30°S following an altitudinal gradient determined by a fog layer. This fragmentation has been attributed to the hyper aridity of the desert. However, periodically climatic events influence the ‘normal seasonality’ of this ecosystem through a higher than average water input that triggers plant responses (e.g. primary productivity and phen...

  2. Rural childhoods in Egypt's desert lands

    OpenAIRE

    Adriansen, Hanne Kristine

    2007-01-01

    Based on fieldwork in Egypt’s desert lands, this paper discusses rural childhoods in an area experiencing rapid social and cultural change. Since 1987, the Egyptian Government has made new villages in the desert as a means to increase agricultural production and solving problems of unemployment. Many settlers move to the Mubarak villages in order to give their children a good start in life. The desert villages are associated with a type of ‘rural idyll’. The process of settling in the de...

  3. Microphytic crusts: 'topsoil' of the desert

    Science.gov (United States)

    Belnap, Jayne

    1990-01-01

    Deserts throughout the world are the home of microphytic, or cryptogamic, crusts. These crusts are dominated by cyanobacteria, previously called blue-green algae, and also include lichens, mosses, green algae, microfungi and bacteria. They are critical components of desert ecosystems, significantly modifying the surfaces on which they occur. In the cold deserts of the Colorado Plateau (including parts of Utah, Arizona, Colorado, and New Mexico), these crusts are extraordinarily well-developed, and may represent 70-80% of the living ground cover.

  4. Desert Dust and Monsoon Rain

    Science.gov (United States)

    Lau, William K. M.; Kim, Kyu-Myong

    2014-01-01

    For centuries, inhabitants of the Indian subcontinent have know that heavy dust events brought on by strong winds occur frequently in the pre-monsoon season, before the onset of heavy rain. Yet scientists have never seriously considered the possibility that natural dust can affect monsoon rainfall. Up to now, most studies of the impacts of aerosols on Indian monsoon rainfall have focused on anthropogenic aerosols in the context of climate change. However, a few recent studies have show that aerosols from antropogenic and natural sources over the Indian subcontinent may affect the transition from break to active monsoon phases on short timescales of days to weeks. Writing in Nature Geoscience, Vinoj and colleagues describe how they have shown that desert dust aerosols over the Arabian Sea and West Asia can strenghten the summer monsoon over the Indial subcontinent in a matter of days.

  5. Biodiversity of nematode assemblages from deep-sea sediments of the Atacama Slope and Trench (South Pacific Ocean)

    Science.gov (United States)

    Gambi, C.; Vanreusel, A.; Danovaro, R.

    2003-01-01

    Nematode assemblages were investigated (in terms of size spectra, sex ratio, Shannon diversity, trophic structure and diversity, rarefaction statistics, maturity index, taxonomic diversity and taxonomic distinctness) at bathyal and hadal depths (from 1050 to 7800 m) in the deepest trench of the South Pacific Ocean: the Trench of Atacama. This area, characterised by very high concentrations of nutritionally-rich organic matter also at 7800-m depth, displayed characteristics typical of eutrophic systems and revealed high nematode densities (>6000 ind. 10 cm -2). Nematode assemblages from the Atacama Trench displayed a different composition than at bathyal depths. At bathyal depths 95 genera and 119 species were found (Comesomatidae, Cyatholaimidae, Microlaimidae, Desmodoridae and Xyalidae being dominant), whereas in the Atacama Trench only 29 genera and 37 species were encountered (dominated by Monhysteridae, Chromadoridae, Microlaimidae, Oxystominidae and Xyalidae). The genus Monhystera (24.4%) strongly dominated at hadal depths and Neochromadora, and Trileptium were observed only in the Atacama Trench, but not at bathyal depths. A reduction of the mean nematode size (by ca. 67%) was observed between bathyal and hadal depths. Since food availability was not a limiting factor in the Atacama Trench sediments, other causes are likely to be responsible for the reduction of nematode species richness and body size. The presence of a restricted number of families and genera in the Atacama Trench might indicate that hadal sediments limited nematode colonisation. Most of the genera reaching very high densities in Trench sediments (e.g., Monhystera) are opportunistic and were responsible for the significant decrease of the maturity index. The dominance of opportunists, which are known to be characterised by small sizes, might have contributed to the reduced nematode size at hadal depths. Shannon diversity and species richness decreased in hadal water depth and this pattern

  6. Desert dust satellite retrieval intercomparison

    Directory of Open Access Journals (Sweden)

    E. Carboni

    2012-01-01

    Full Text Available This work provides a comparison of satellite retrievals of Saharan desert dust aerosol optical depth (AOD during a strong dust event through March 2006. In this event, a large dust plume was transported over desert, vegetated, and ocean surfaces. The aim is to identify and understand the differences between current algorithms, and hence improve future retrieval algorithms. The satellite instruments considered are AATSR, AIRS, MERIS, MISR, MODIS, OMI, POLDER, and SEVIRI. An interesting aspect is that the different algorithms make use of different instrument characteristics to obtain retrievals over bright surfaces. These include multi-angle approaches (MISR, AATSR, polarisation measurements (POLDER, single-view approaches using solar wavelengths (OMI, MODIS, and the thermal infrared spectral region (SEVIRI, AIRS. Differences between instruments, together with the comparison of different retrieval algorithms applied to measurements from the same instrument, provide a unique insight into the performance and characteristics of the various techniques employed. As well as the intercomparison between different satellite products, the AODs have also been compared to co-located AERONET data. Despite the fact that the agreement between satellite and AERONET AODs is reasonably good for all of the datasets, there are significant differences between them when compared to each other, especially over land. These differences are partially due to differences in the algorithms, such as assumptions about aerosol model and surface properties. However, in this comparison of spatially and temporally averaged data, at least as significant as these differences are sampling issues related to the actual footprint of each instrument on the heterogeneous aerosol field, cloud identification and the quality control flags of each dataset.

  7. Accumulation of impact markers in desert wetlands and implications for the Younger Dryas impact hypothesis

    Science.gov (United States)

    Pigati, Jeffrey S.; Latorre, Claudio; Rech, Jason A.; Betancourt, Julio L.; Martinez, Katherine E.; Budahn, James R.

    2012-01-01

    The Younger Dryas impact hypothesis contends that an extraterrestrial object exploded over North America at 12.9 ka, initiating the Younger Dryas cold event, the extinction of many North American megafauna, and the demise of the Clovis archeological culture. Although the exact nature and location of the proposed impact or explosion remain unclear, alleged evidence for the fallout comes from multiple sites across North America and a site in Belgium. At 6 of the 10 original sites (excluding the Carolina Bays), elevated concentrations of various "impact markers" were found in association with black mats that date to the onset of the Younger Dryas. Black mats are common features in paleowetland deposits and typically represent shallow marsh environments. In this study, we investigated black mats ranging in age from approximately 6 to more than 40 ka in the southwestern United States and the Atacama Desert of northern Chile. At 10 of 13 sites, we found elevated concentrations of iridium in bulk and magnetic sediments, magnetic spherules, and/or titanomagnetite grains within or at the base of black mats, regardless of their age or location, suggesting that elevated concentrations of these markers arise from processes common to wetland systems, and not a catastrophic extraterrestrial impact event.

  8. Measurement of SO2 and BrO at Lastarria, Lascar, and Salar de Atacama

    Science.gov (United States)

    Dinger, Florian; Osorio, Matias; Gliß, Jonas; Lübcke, Peter; Bobrowski, Nicole; Platt, Ulich; Frins, Erna; Wagner, Thomas

    2015-04-01

    In November 2014 the 12th CCVG (Commission of the Chemistry of Volcanic Gases) gas workshop took place in Northern Chile. Subject of the field trips were Lastarria (25°10' S, 68°30' W) and Lascar (23°22' S, 67°43' W), both stratovolcanoes with a height of 5700 and 5600 a.s.l., respectively. One of the goals was to investigate the SO2 and BrO emissions of these volcanoes by remote-sensing using Multi-AXial Differential Optical Absorption Spectroscopy (MAX-DOAS). The used 'mini MAX-DOAS' instrument measures scattered solar UV radiation recording spectra within a wavelength range of 294-437 nm and with a spectral resolution of 0.9 nm. The instrument took spectra sequentially at various elevation angles scanning the sky from horizon to zenith. The scanning geometry was adapted to each measurement location. At Lastarria volcano we observed SO2 slant column densities (SCDs) in the order of 1018 molecules/cm2 and BrO SCDs up to 5 - 1013 molecules/cm2. At Lascar volcano we observed SO2 SCDs up to 4 - 1017 molecules/cm2 but no significant BrO absorption features (in a preliminary evaluation). We will present SO2 fluxes and upper detection limits of BrO, and present maxima BrO/SO2 ratios of Lastarria and Lascar. Those ratios will be compared to BrO/SO2 ratios of other - previously studied - Andean volcanoes (e.g. Villarica). Furthermore, we measured the SO2 and BrO SCDs above the Salar de Atacama (23°30' S, 68°15' W), a salt pan with an area of 3000 km2. Spectra were taken in a direction where the Salar de Atacama has an extension of about 50 km and no other obvious emission sources were contributing to the SO2 and BrO absorption signals. At the Salar de Atacama we observed SO2 SCDs up to 2 - 1017 molecules/cm2 and BrO SCDs of up to 7 - 1013 molecules/cm2.

  9. Desert Cyanobacteria under simulated space and Martian conditions

    Science.gov (United States)

    Billi, D.; Ghelardini, P.; Onofri, S.; Cockell, C. S.; Rabbow, E.; Horneck, G.

    2008-09-01

    The environment in space and on planets such as Mars, can be lethal to living organisms and high levels of tolerance to desiccation, cold and radiation are needed for survival: rock-inhabiting cyanobacteria belonging to the genus Chroococcidiopsis can fulfil these requirements [1]. These cyanobacteria constantly appear in the most extreme and dry habitats on Earth, including the McMurdo Dry Valleys (Antarctica) and the Atacama Desert (Chile), which are considered the closest terrestrial analogs of two Mars environmental extremes: cold and aridity. In their natural environment, these cyanobacteria occupy the last refuges for life inside porous rocks or at the stone-soil interfaces, where they survive in a dry, dormant state for prolonged periods. How desert strains of Chroococcidiopsis can dry without dying is only partially understood, even though experimental evidences support the existence of an interplay between mechanisms to avoid (or limit) DNA damage and repair it: i) desert strains of Chroococcidiopsis mend genome fragmentation induced by ionizing radiation [2]; ii) desiccation-survivors protect their genome from complete fragmentation; iii) in the dry state they show a survival to an unattenuated Martian UV flux greater than that of Bacillus subtilis spores [3], and even though they die following atmospheric entry after having orbited the Earth for 16 days [4], they survive to simulated shock pressures up to 10 GPa [5]. Recently additional experiments were carried out at the German Aerospace Center (DLR) of Cologne (Germany) in order to identify suitable biomarkers to investigate the survival of Chroococcidiopsis cells present in lichen-dominated communities, in view of their direct and long term space exposition on the International Space Station (ISS) in the framework of the LIchens and Fungi Experiments (LIFE, EXPOSEEuTEF, ESA). Multilayers of dried cells of strains CCMEE 134 (Beacon Valley, Antarctica), and CCMEE 123 (costal desert, Chile ), shielded by

  10. Manado: A Developing Coast

    OpenAIRE

    Tenthof van Noorden, C.; Vermeij, D.; Van Zuijlen, J.; Zeelenberg, W.

    2013-01-01

    Manado, the capital city of North Sulawesi in Indonesia, is rapidly developing. The last years Manado has been extending into the sea, which changed the hydraulics and morphology of Manado Bay. This had negative effects on the currents, inducing erosion along the coast. Also Manado has problems with the presence of garbage in the rivers and river flooding. Now the municipality is planning to build a new reclamation, which might even increase these problems. Based on the requests of our client...

  11. Proposed Desert Pupfish Preserve : Supplemental LARC Report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document contains supplements to a previous report on the desert pupfish preserve proposal. The attachments are titled: “Vertebrate Animals and Vascular...

  12. The New Critical Reading of Desert Places

    Institute of Scientific and Technical Information of China (English)

    BING Zhao-yu

    2013-01-01

    From the perspective of new criticism, this article attempts at a profound study of Robert Frost’s Desert Places so as to better understand the value, reveal the meaning and enjoy the charm of this works.

  13. Vegetation - Central Mojave Desert [ds166

    Data.gov (United States)

    California Department of Resources — The Department of Defense and the other desert managers are developing and organizing scientific information needed to better manage the natural resources of the...

  14. Self-propelled Desert Workover Rig

    Institute of Scientific and Technical Information of China (English)

    Liu Xin; Xie Pengming; Shi Bing

    1996-01-01

    @@ The Taklimakan Desert in the Taxim Basin of western China is the second largest desert in the world. Its relative elevation is 100- 150 m, somewhere 200-300 m. The annual amount of precipitation is 25 mm to 40 mm in most area and less than 15 mm in the east area. the annual amount of evaporation is usually between 2 100 mm and 3 400 mm.

  15. The Atacama Cosmology Telescope: Calibration with WMAP Using Cross-Correlations

    CERN Document Server

    Hajian, Amir; Ade, Peter A R; Aguirre, Paula; Amiri, Mandana; Appel, John William; Barrientos, L Felipe; Battistelli, Elia S; Bond, J Richard; Brown, Ben; Burger, Bryce; Chervenak, Jay; Das, Sudeep; Devlin, Mark J; Dicker, Simon R; Doriese, W Bertrand; Dunkley, Joanna; Dunner, Rolando; Essinger-Hileman, Thomas; Fisher, Ryan P; Fowler, Joseph W; Halpern, Mark; Hasselfield, Matthew; Hernandez-Monteagudo, Carlos; Hilton, Gene C; Hilton, Matt; Hincks, Adam D; Hlozek, Renee; Huffenberger, Kevin M; Hughes, David H; Hughes, John P; Infante, Leopoldo; Irwin, Kent D; Juin, Jean Baptiste; Kaul, Madhuri; Klein, Jeff; Kosowsky, Arthur; Lau, Judy M; Limon, Michele; Lin, Yen-Ting; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Mauskopf, Phil; Menanteau, Felipe; Moodley, Kavilan; Moseley, Harvey; Netterfield, Calvin B; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Partridge, Bruce; Reid, Beth; Sehgal, Neelima; Sherwin, Blake D; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Trac, Hy; Tucker, Carole; Warne, Ryan; Wollack, Ed; Zhao, Yue

    2010-01-01

    We present a new calibration method based on cross-correlations with WMAP and apply it to data from the Atacama Cosmology Telescope (ACT). ACT's observing strategy and map making procedure allows an unbiased reconstruction of the modes in the maps over a wide range of multipoles. By directly matching the ACT maps to WMAP observations in the multipole range of 400 < ell < 1000, we determine the absolute calibration with an uncertainty of 2% in temperature. The precise measurement of the calibration error directly impacts the uncertainties in the cosmological parameters estimated from the ACT power spectra. We also present a combined map based on ACT and WMAP data that has high signal-to-noise over a wide range of multipoles.

  16. ACTPol: A polarization-sensitive receiver for the Atacama Cosmology Telescope

    CERN Document Server

    Niemack, M D; Aguirre, J; Barrientos, F; Beall, J A; Bond, J R; Britton, J; Cho, H M; Das, S; Devlin, M J; Dicker, S; Dunkley, J; Dunner, R; Fowler, J W; Hajian, A; Halpern, M; Hasselfield, M; Hilton, G C; Hilton, M; Hubmayr, J; Hughes, J P; Infante, L; Irwin, K D; Jarosik, N; Klein, J; Kosowsky, A; Marriage, T A; McMahon, J; Menanteau, F; Moodley, K; Nibarger, J P; Nolta, M R; Page, L A; Partridge, B; Reese, E D; Sievers, J; Spergel, D N; Staggs, S T; Thornton, R; Tucker, C; Wollack, E; Yoon, K W

    2010-01-01

    The six-meter Atacama Cosmology Telescope (ACT) in Chile was built to measure the cosmic microwave background (CMB) at arcminute angular scales. We are building a new polarization sensitive receiver for ACT (ACTPol). ACTPol will characterize the gravitational lensing of the CMB and aims to constrain the sum of the neutrino masses with ~0.05 eV precision, the running of the spectral index of inflation-induced fluctuations, and the primordial helium abundance to better than 1%. Our observing fields will overlap with the SDSS BOSS survey at optical wavelengths, enabling a variety of cross-correlation science, including studies of the growth of cosmic structure from Sunyaev-Zel'dovich observations of clusters of galaxies as well as independent constraints on the sum of the neutrino masses. We describe the science objectives and the initial receiver design.

  17. The kinematic and geodynamic significance of the Atacama fault zone, northern Chile

    Science.gov (United States)

    Scheuber, Ekkehard; Andriessen, Paul A. M.

    The Atacama fault zone (AFZ) is the dominant feature in the structure of the North Chilean Coastal Cordillera. Left lateral displacement took place along its system of longitudinal faults during the Jurassic and early Cretaceous. This development was contemporaneous with arc magmatism and was later reactivated, resulting in a steep normal fault. Strike-slip movements along the AFZ consist of two sets of ductile shear zones of different ages: one Jurassic, formed under amphibolite-facies conditions; the other early Cretaceous, with greenschist-facies mylonites. Structural asymmetries point to a sinistral sense of shear in both sets. The AFZ can be interpreted as a magmatic arc structure which accommodated the oblique subduction of an oceanic plate (trench-linked strike-slip fault). The sinistral sense of shear is consistent with reconstructions of late Jurassic to early Cretaceous plate configurations in the SE Pacific.

  18. Cenozoic evolution of the northwestern Salar de Atacama Basin, northern Chile

    Science.gov (United States)

    Pananont, P.; Mpodozis, C.; Blanco, N.; Jordan, T. E.; Brown, L. D.

    2004-12-01

    Since 90 Ma, the nonmarine Salar de Atacama Basin has been the largest, deepest, and most persistent sedimentary basin of northern Chile. Integration of 200 km of two-dimensional seismic reflection data with surface geological data clarifies Oligocene and Neogene evolution of the northern part of the basin. A normal fault with 6 ± 1 km of vertical separation controlled the western boundary of the basin during the accumulation of the Oligocene-lower Miocene Paciencia Group. The combination of this structure, a similar one in the Calama Basin, and regional structural data suggests that localized extension played an important role within a tectonic environment dominated by margin-perpendicular compression and margin-parallel strike-slip deformation. Seismic data substantiate the surface interpretation that much of the Cordillera de la Sal ridge resulted from diapiric flow of the Paciencia Group. Diapiric flow initiated during the late early Miocene or middle Miocene, associated with a deep reverse fault.

  19. Science with the Atacama Large Millimeter Array A New Era for Astrophysics

    CERN Document Server

    Bachiller, Rafael

    2008-01-01

    Currently under construction in the Andean Altiplano, Northern Chile, the Atacama Large Millimeter Array (ALMA) is the most ambitious astronomy facility under construction. ALMA is a radio interferometer composed of 54 antennas of 12 m diameter, and twelve 7 m antennas with about 6600 square meters of total collecting area. Initially covering the most interesting spectral wavelength ranges from 3 to 0.3 mm, ALMA will be a revolutionary telescope aimed to unveil the details of star and planet formation and to provide astronomy with the first exhaustive view of the dark and youngest objects of the Universe. This book describes the enormous capabilities of ALMA, the state of the project, and most notably the scientific prospects with such a unique facility. The book includes comprehensive reviews and recent results on most hot topics of modern Astronomy (the formation and evolution of galaxies, the physics and chemistry of the interstellar medium, and the processes of star and planet formation) with prospects to...

  20. THE ATACAMA COSMOLOGY TELESCOPE: CALIBRATION WITH THE WILKINSON MICROWAVE ANISOTROPY PROBE USING CROSS-CORRELATIONS

    International Nuclear Information System (INIS)

    We present a new calibration method based on cross-correlations with the Wilkinson Microwave Anisotropy Probe (WMAP) and apply it to data from the Atacama Cosmology Telescope (ACT). ACT's observing strategy and map-making procedure allows an unbiased reconstruction of the modes in the maps over a wide range of multipoles. By directly matching the ACT maps to WMAP observations in the multipole range of 400 < l < 1000, we determine the absolute calibration with an uncertainty of 2% in temperature. The precise measurement of the calibration error directly impacts the uncertainties in the cosmological parameters estimated from the ACT power spectra. We also present a combined map based on ACT and WMAP data that has a high signal-to-noise ratio over a wide range of multipoles.

  1. The Atacama Cosmology Telescope: Two-Season ACTPol Spectra and Parameters

    CERN Document Server

    Louis, Thibaut; Hasselfield, Matthew; Lungu, Marius; Maurin, Loïc; Addison, Graeme E; Ade, Peter A R; Aiola, Simone; Allison, Rupert; Amiri, Mandana; Angile, Elio; Battaglia, Nicholas; Beall, James A; de Bernardis, Francesco; Bond, J Richard; Britton, Joe; Calabrese, Erminia; Cho, Hsiao-mei; Choi, Steve K; Coughlin, Kevin; Crichton, Devin; Crowley, Kevin; Datta, Rahul; Devlin, Mark J; Dicker, Simon R; Dunkley, Joanna; Dünner, Rolando; Ferraro, Simone; Fox, Anna E; Gallardo, Patricio; Gralla, Megan; Halpern, Mark; Henderson, Shawn; Hill, J Colin; Hilton, Gene C; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Ho, S P Patty; Huang, Zhiqi; Hubmayr, Johannes; Huffenberger, Kevin M; Hughes, John P; Infante, Leopoldo; Irwin, Kent; Kasanda, Simon Muya; Klein, Jeff; Koopman, Brian; Kosowsky, Arthur; Li, Dale; Madhavacheril, Mathew; Marriage, Tobias A; McMahon, Jeff; Menanteau, Felipe; Moodley, Kavilan; Munson, Charles; Naess, Sigurd; Nati, Federico; Newburgh, Laura; Nibarger, John; Niemack, Michael D; Nolta, Michael R; Nuñez, Carolina; Page, Lyman A; Pappas, Christine; Partridge, Bruce; Rojas, Felipe; Schaan, Emmanuel; Schmitt, Benjamin L; Sehgal, Neelima; Sherwin, Blake D; Sievers, Jon; Simon, Sara; Spergel, David N; Staggs, Suzanne T; Switzer, Eric R; Thornton, Robert; Trac, Hy; Treu, Jesse; Tucker, Carole; Van Engelen, Alexander; Ward, Jonathan T; Wollack, Edward J

    2016-01-01

    We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time data collected during 2013-14 using two detector arrays at 149 GHz, from 548 deg$^2$ of sky on the celestial equator. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008-10, in combination with Planck and WMAP data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the LCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters than the ACTPol temperature spectrum, including the baryon density, the acoustic peak angular scale, and the derived Hubble constant. Adding the new data to planck temperature data tightens the limits on damping tail parameters, for example reducing the joint uncertainty on the number of neutrino species and the primordial he...

  2. Thermally evolved gas analysis (TEGA) of hyperarid soils doped with microorganisms from the Atacama Desert in southern Peru: Implications for the Phoenix mission

    Science.gov (United States)

    Valdivia-Silva, Julio E.; Navarro-González, Rafael; McKay, Christopher

    2009-07-01

    TEGA, one of several instruments on board of the Phoenix Lander, performed differential scanning calorimetry and evolved gas analysis of soil samples and ice, collected from the surface and subsurface at a northern landing site on Mars. TEGA is a combination of a high temperature furnace and a mass spectrometer (MS) that was used to analyze samples delivered to the instrument via a robotic arm. The samples were heated at a programmed ramp rate up to 1000 °C. The power required for heating can be carefully and continuously monitored (scanning calorimetry). The evolved gases generated during the process can be analyzed with the evolved gas analyzer (a magnetic sector mass spectrometer) in order to determine the composition of gases released as a function of temperature. Our laboratory has developed a sample characterization method using a pyrolyzer integrated to a quadrupole mass spectrometer to support the interpretations of TEGA data. Here we examine the evolved gas properties of six types of hyperarid soils from the Pampas de La Joya in southern Peru (a possible analog to Mars), to which we have added with microorganisms ( Salmonella typhimurium, Micrococcus luteus, and Candida albicans) in order to investigate the effect of the soil matrix on the TEGA response. Between 20 and 40 mg of soil, with or without ˜5 mg of lyophilized microorganism biomass (dry weight), were placed in the pyrolyzer and heated from room temperature to 1200 °C in 1 h at a heating rate of 20 °C/min. The volatiles released were transferred to a MS using helium as a carrier gas. The quadrupole MS was ran in scan mode from 10 to 200 m/z. In addition, ˜20 mg of each microorganism without a soil matrix were analyzed. As expected, there were significant differences in the gases released from microorganism samples with or without a soil matrix, under similar heating conditions. Furthermore, samples from the most arid environments had significant differences compared with less arid soils. Organic carbon released in the form of CO 2 (ion 44 m/z) from microorganisms evolved at temperatures of ˜326.0 ± 19.5 °C, showing characteristic patterns for each one. Others ions such as 41, 78 and 91 m/z were also found. Interestingly, during the thermal process, the release of CO 2 increased and ions previously found disappeared, demonstrating a high-oxidant activity in the soil matrix when it was subjected to high temperature. Finally, samples of soil show CO 2 evolved up to 650 °C consistent with thermal decomposition of carbonates. These results indicate that organics mixed with these hyperarid soils are oxidized to CO 2. Our results suggest the existence of at least two types of oxidants in these soils, a thermolabile oxidant which is highly oxidative and other thermostable oxidant which has a minor oxidative activity and that survives the heat-treatment. Furthermore, we find that the interaction of biomass added to soil samples gives a different set of breakdown gases than organics resident in the soil. The nature of oxidant(s) present in the soils from Pampas de La Joya is still unknown.

  3. Desert Amplification in a Warming Climate

    Science.gov (United States)

    Zhou, Liming

    2016-08-01

    Here I analyze the observed and projected surface temperature anomalies over land between 50°S-50°N for the period 1950–2099 by large-scale ecoregion and find strongest warming consistently and persistently seen over driest ecoregions such as the Sahara desert and the Arabian Peninsula during various 30-year periods, pointing to desert amplification in a warming climate. This amplification enhances linearly with the global mean greenhouse gases(GHGs) radiative forcing and is attributable primarily to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surface over drier ecoregions as a consequence of a warmer and thus moister atmosphere in response to increasing GHGs. These results indicate that desert amplification may represent a fundamental pattern of global warming associated with water vapor feedbacks over land in low- and mid- latitudes where surface warming rates depend inversely on ecosystem dryness. It is likely that desert amplification might involve two types of water vapor feedbacks that maximize respectively in the tropical upper troposphere and near the surface over deserts, with both being very dry and thus extremely sensitive to changes of water vapor.

  4. Background-like nitrate in desert air

    Science.gov (United States)

    Wu, Feng; Zhang, Daizhou; Cao, Junji; Zhang, Ting; An, Zhisheng

    2014-02-01

    The atmospheric nitrogen cycle is a key process driving the earth's environmental evolution. Current model studies require knowledge of NOx soil emissions from various land types, but desert emissions remain unquantified or are not addressed with high confidence. Our measurements at two observatories in Taklimakan desert during a dust episode showed an approximately stable and dust-independent nitrate in the air. Its concentration estimated from PM2.5, PM10 and TSP samples under non-dust, floating dust and dust storm conditions was 3.81 ± 1.24 μg m-3, 2.95 ± 0.69 μg m-3, 4.99 ± 1.71 μg m-3, respectively, despite the more-than-one-order difference of dust loading. This concentration was much larger than that in remote marine and tropical forest air. Comprehensive investigation revealed a similar presence of nitrate in other desert air. The nitrate was hypothesized to be the consequence of the conversion of NOx released from desert soils. These results indicate a background-like nitrate and active reactions of nitrogen compounds in desert air.

  5. Desert Amplification in a Warming Climate

    Science.gov (United States)

    Zhou, Liming

    2016-01-01

    Here I analyze the observed and projected surface temperature anomalies over land between 50°S-50°N for the period 1950–2099 by large-scale ecoregion and find strongest warming consistently and persistently seen over driest ecoregions such as the Sahara desert and the Arabian Peninsula during various 30-year periods, pointing to desert amplification in a warming climate. This amplification enhances linearly with the global mean greenhouse gases(GHGs) radiative forcing and is attributable primarily to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surface over drier ecoregions as a consequence of a warmer and thus moister atmosphere in response to increasing GHGs. These results indicate that desert amplification may represent a fundamental pattern of global warming associated with water vapor feedbacks over land in low- and mid- latitudes where surface warming rates depend inversely on ecosystem dryness. It is likely that desert amplification might involve two types of water vapor feedbacks that maximize respectively in the tropical upper troposphere and near the surface over deserts, with both being very dry and thus extremely sensitive to changes of water vapor. PMID:27538725

  6. Desert Amplification in a Warming Climate.

    Science.gov (United States)

    Zhou, Liming

    2016-01-01

    Here I analyze the observed and projected surface temperature anomalies over land between 50°S-50°N for the period 1950-2099 by large-scale ecoregion and find strongest warming consistently and persistently seen over driest ecoregions such as the Sahara desert and the Arabian Peninsula during various 30-year periods, pointing to desert amplification in a warming climate. This amplification enhances linearly with the global mean greenhouse gases(GHGs) radiative forcing and is attributable primarily to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surface over drier ecoregions as a consequence of a warmer and thus moister atmosphere in response to increasing GHGs. These results indicate that desert amplification may represent a fundamental pattern of global warming associated with water vapor feedbacks over land in low- and mid- latitudes where surface warming rates depend inversely on ecosystem dryness. It is likely that desert amplification might involve two types of water vapor feedbacks that maximize respectively in the tropical upper troposphere and near the surface over deserts, with both being very dry and thus extremely sensitive to changes of water vapor. PMID:27538725

  7. Salar de Atacama basin: A record of compressional tectonics in the central Andes since the mid-Cretaceous

    OpenAIRE

    ARRIAGADA, César; Cobbold, Peter,; Roperch, Pierrick

    2006-01-01

    19 p.; International audience; The Salar de Atacama basin lies in the inner fore arc of northern Chile. Topographically and structurally, it is a first-order feature of the central Andes. The sedimentary fill of the basin constrains the timing and extent of crustal deformation since the mid-Cretaceous. We have studied good exposures along the western edge of the basin and have correlated them with seismic reflection sections and data from an exploration well. Throughout most of its history, t...

  8. Application of PIXE to the characterization of vitreous dacites from archaeolgical sites in the Atacama region in northern Chile

    Energy Technology Data Exchange (ETDEWEB)

    Morales, J.R.; Cancino, S. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Nunoa, Santiago 1 (Chile); Miranda, P. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Nunoa, Santiago 1 (Chile)], E-mail: pjmirand@gmail.com; Dinator, M.I. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Nunoa, Santiago 1 (Chile); Seelenfreund, A. [Universidad Academia de Humanismo Cristiano, Condell 343, Providencia, Santiago (Chile)

    2007-11-15

    Geochemical characterization studies using PIXE were carried out on 21 vitreous dacite artifacts from early formative archaeological sites in the Atacama region, in northern Chile, and on 13 samples taken from two potential volcanic sources located within the region. Performing statistical analyses it was possible to obtain elemental concentration patterns for the archaeological samples of this material and match some of these artifacts with the geological source samples.

  9. The intersection of climate, tectonic uplift, and regional groundwater flow in the central Andean Plateau: Insight from the accumulation of the massive evaporite deposit in the Salar de Atacama, Chile

    Science.gov (United States)

    Boutt, D. F.; Hynek, S. A.; Corenthal, L.; Munk, L. A.

    2015-12-01

    The Salar de Atacama (SdA), a large endorheic basin adjacent to the Central Andes in the hyperarid Atacama Desert, has accumulated over 1800 km3 of evaporites and a lithium-rich brine since the late Miocene. Focused groundwater discharge in endorheic basins, such as those in the Chilean Altiplano, provide opportunities to investigate mechanisms for closing hydrologic budgets in arid regions. We demonstrate that modern evapotranspiration is 5 to 21 times greater than modern recharge from precipitation in the topographic watershed. Multiple lines of evidence including an adapted chloride mass balance method applied to remotely sensed precipitation estimates and sodium mass balance calculations support this conclusion. We contend that the missing water needed to close the extreme hydrologic imbalance of SdA is sourced from recharge on the orogenic plateau in an area over 4 times larger than the topographic watershed, augmented by transient draining of stored groundwater. Groundwater recharged during wetter periods in the late Pleistocene is still actively draining and discharging from storage without corresponding recharge into the system. Geologic evidence from the volume of evaporites deposited in the basin suggests that the SdA has been receiving significant amounts of fresh inflow waters over at least 7 Ma despite the region being hyperarid over the same time frame. Our conceptualization of the depositional model for evaporite accumulation necessitates the water table being at or close to the land surface. Subsidence associated with basin development has accommodated significant accumulation of these deposits thereby requiring the sustenance of fresh inflow waters during uplift of the Andean plateau. Sustained groundwater discharge to the basin requires long residence times, deep water tables and strong gradients in landscape and climate enabled by an uplifting plateau. The application of steady state assumptions to the modern hydrologic system are unsupported by

  10. Ecological stability of Tarim Desert Highway shelterbelt

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhibin; XU Xinwen; LEI Jiaqiang; LI Shengyu

    2006-01-01

    The Tarim Desert Highway shelterbelt,located in hinterland of Taklimakan Desert, is irrigated by underground saline water, with three to thirty gram per litter mineral degrees. The sustainability and stability are affected by multifarious stress.The structural and functional characteristics of shelterbelt are studied to probe into correlation between environment and shelterbelt. On basis, decision analysis is applied to study ecological stability of the Tarim Desert Highway shelterbelt, to screen out limited factors, to establish general index system, and to evaluate the stability of the shelterbelt nowadays.Finally, the concept of ecological stability is utilized to manage the artificial ecosystem. The results show that the artificial ecosystem is relatively flimsy, whose stability can be increased by adjusting stand structure and improving the nutrient cycle.

  11. Plant ecology of the Namib desert

    Directory of Open Access Journals (Sweden)

    P. Van Damme

    1991-01-01

    Full Text Available The Namib desert is reportedly the oldest desert in the world. It consists of a number of very distinct ecosystems, six of which are dealt with in this text. Among them are the sand dune, the dry river bed and the domed inselbergs vegetation. The importance of fog water absorption for the Namib flora is discussed. Two important and noteworthy endemic plant species, i.e. Welwitschia mirabilis and Acanthosicyos horrida are treated extensively, because of their great interest for plant physiology and ethnobotany, resp. Special attention is given to the importance of the CAM photosynthetic system for Namib desert plant survival. Where possible the ethnobotanic importance of the species is discussed.

  12. The Northern Path of Asian Dust Transport from the Gobi Desert to North America

    Institute of Scientific and Technical Information of China (English)

    CHEN Ke-Yi

    2010-01-01

    The aerosol index(AI)of the Total Ozone Mapping Spectrometer(TOMS)satellite data(1979-2001)was analyzed to reveal the climatological long-distance path of dust transport from Asia to North America.The AI in the west coast of the United States is highly correlated with that in the Gobi desert.Additionally,from the TOMS satellite images,it can be seen that very strong plumes advect from Asia to the west coast of North America in typical dust storm cases.When applying the sourcereceptor relationship to detect the northern dust transport path between the Gobi source region and the west coast of the United States receptor region,it is evident that the dust plume can be transported northward beyond 60°N from its source region and that it takes 5 to 6 days to reach the west coast of the United States.The cross correlation technique shown in this work is a useful tool that can be applied in other regions to give useful insights into relationships between major dust sources and downwind receptor locations by using remotely sensed dust observations.

  13. Long-term accumulation of atmospheric dust in rocky deserts

    NARCIS (Netherlands)

    Goossens, D.; Offer, Z.Y.

    2005-01-01

    The spatial pattern of long-term (hundreds to thousands of years) accumulation of dust in rocky deserts was investigated in the northern Negev Desert of Israel. The concentration of dust in the desert subsoil was measured at 41 locations in a 53 ha test area for which detailed information exists on

  14. Jojoba could stop the desert creep

    Energy Technology Data Exchange (ETDEWEB)

    1982-03-25

    The Sahara desert is estimated to be expanding at a rate of 5km a year. The Sudanese government is experimenting with jojoba in six different regions as the bush has the potential to stop this ''desert creep''. The plant, a native to Mexico, is long known for its resistance to drought and for the versatile liquid wax that can be extracted from its seeds. It is estimated that one hectare of mature plants could produce 3000 kg of oil, currently selling at $50 per litre, and so earn valuable foreign currency.

  15. Chen Yadan Braves the Lop Desert

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    BOARDING the airplane to Urumuqi on October 29, 1997, Chen Yadan felt incredibly excited. She was finally about to embark on the Lop Desert journey she had planned for ten years. The artist was adventuring into the desert, not only to sketch its special charm with her pencils, but to follow the footsteps that her father left behind 60 years ago. She was yearning to experience the formidable struggle taken by the old generation of scientists. Chen Yadan’s father, Chen Zongqi, had been the deputy director of the

  16. Indian Ocean coasts, coastal ecology

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.

    stream_size 9 stream_content_type text/plain stream_name Encycl_Coast_Sci_2005_546.pdf.txt stream_source_info Encycl_Coast_Sci_2005_546.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  17. New Insights in Preservation of Meteorites in Hot Deserts: The Oldest Hot Desert Meteorite Collection.

    Science.gov (United States)

    Hutzler, A.; Rochette, P.; Bourlès, D.; Gattacceca, J.; Merchel, S.; Jull, A. J. T.; Valenzuela, M.

    2016-08-01

    Terrestrial ages of a subset of a chilean meteorite collection have been determined with cosmogenic nuclides. We show here that provided the environnement is favorable enough, hot desert meteorites can survive over a million year.

  18. The Atacama Cosmology Telescope: Cosmological parameters from three seasons of data

    CERN Document Server

    Sievers, Jonathan L; Nolta, Michael R; Acquaviva, Viviana; Addison, Graeme E; Ade, Peter A R; Aguirre, Paula; Amiri, Mandana; Appel, John William; Barrientos, L Felipe; Battistelli, Elia S; Battaglia, Nick; Bond, J Richard; Brown, Ben; Burger, Bryce; Calabrese, Erminia; Chervenak, Jay; Crichton, Devin; Das, Sudeep; Devlin, Mark J; Dicker, Simon R; Doriese, W Bertrand; Dunkley, Joanna; Dünner, Rolando; Essinger-Hileman, Thomas; Faber, David; Fisher, Ryan P; Fowler, Joseph W; Gallardo, Patricio; Gordon, Michael S; Gralla, Megan B; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hernández-Monteagudo, Carlos; Hill, J Colin; Hilton, Gene C; Hilton, Matt; Hincks, Adam D; Holtz, Dave; Huffenberger, Kevin M; Hughes, David H; Hughes, John P; Infante, Leopoldo; Irwin, Kent D; Jacobson, David R; Johnstone, Brittany; Juin, Jean Baptiste; Kaul, Madhuri; Klein, Jeff; Kosowsky, Arthur; Lau, Judy M; Limon, Michele; Lin, Yen-Ting; Louis, Thibaut; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Martocci, Krista; Mauskopf, Phil; McLaren, Michael; Menanteau, Felipe; Moodley, Kavilan; Moseley, Harvey; Netterfield, Calvin B; Niemack, Michael D; Page, Lyman A; Page, William A; Parker, Lucas; Partridge, Bruce; Plimpton, Reed; Quintana, Hernan; Reese, Erik D; Reid, Beth; Rojas, Felipe; Sehgal, Neelima; Sherwin, Blake D; Schmitt, Benjamin L; Spergel, David N; Staggs, Suzanne T; Stryzak, Omelan; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Trac, Hy; Tucker, Carole; Uehara, Masao; Visnjic, Katerina; Warne, Ryan; Wilson, Grant; Wollack, Ed; Zhao, Yue; Zuncke, Caroline

    2013-01-01

    We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz and 218 GHz made by the Atacama Cosmology Telescope (ACT) in three seasons of observations from 2008 to 2010. A model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal and kinematic Sunyaev-Zeldovich (SZ) effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources, and the correlation between the thermal SZ effect and infrared sources. The power ell^2 C_ell/2pi of the thermal SZ power spectrum at 148 GHz is measured to be 3.4 +/-1.4 muK^2 at ell=3000, while the corresponding amplitude of the kinematic SZ power spectrum has a 95 percent confidence level upper limit of 8.6 muK^2. Combining ACT power spectra with the WMAP 7-year temperature and polarization power spectra, we find excellent consistency with the LCDM model. We constrain...

  19. The Atacama Cosmology Telescope (ACT): Beam Profiles and First SZ Cluster Maps

    CERN Document Server

    Hincks, A D; Ade, P; Aguirre, P; Amiri, M; Appel, J W; Barrientos, L F; Battistelli, E S; Bond, J R; Brown, B; Burger, B; Chervenak, J; Das, S; Devlin, M J; Dicker, S; Doriese, W B; Dunkley, J; Dünner, R; Essinger-Hileman, T; Fisher, R P; Fowler, J W; Hajian, A; Halpern, M; Hasselfield, M; Hernández-Monteagudo, C; Hilton, G C; Hilton, M; Hlozek, R; Huffenberger, K; Hughes, D; Hughes, J P; Infante, L; Irwin, K D; Jiménez, R; Juin, J B; Kaul, M; Klein, J; Kosowsky, A; Lau, J M; Limon, M; Lin, Y -T; Lupton, R H; Marriage, T; Marsden, D; Martocci, K; Mauskopf, P; Menanteau, F; Moodley, K; Moseley, H; Netterfield, C B; Niemack, M D; Nolta, M R; Page, L A; Parker, L; Partridge, B; Quintana, H; Reid, B; Sehgal, N; Sievers, J; Spergel, D N; Staggs, S T; Stryzak, O; Swetz, D; Switzer, E; Thornton, R; Trac, H; Tucker, C; Verde, L; Warne, R; Wilson, G; Wollack, E; Zhao, Y

    2009-01-01

    The Atacama Cosmology Telescope (ACT) is currently observing the cosmic microwave background with arcminute resolution at 148 GHz, 218 GHz, and 277 GHz. In this paper, we present ACT's first results. Data have been analyzed using a maximum-likelihood map-making method which uses B-splines to model and remove the atmospheric signal. It has been used to make high-precision beam maps from which we determine the experiment's window functions. This beam information directly impacts all subsequent analyses of the data. We also used the method to map a sample of galaxy clusters via the Sunyaev-Zel'dovich (SZ) effect, and show eight clusters previously detected in the X-ray or SZ and two new cluster candidates. We provide integrated Compton-y measurements for each cluster. Of particular interest is our detection of the z = 0.44 component of Abell 3128 and our current non-detection of the low-redshift part, providing strong evidence that the further cluster is more massive as suggested by X-ray measurements. This is a...

  20. The Atacama Cosmology Telescope: Cosmological Parameters from the 2008 Power Spectra

    CERN Document Server

    Dunkley, J; Sievers, J; Acquaviva, V; Ade, P A R; Aguirre, P; Amiri, M; Appel, J W; Barrientos, L F; Battistelli, E S; Bond, J R; Brown, B; Burger, B; Chervenak, J; Das, S; Devlin, M J; Dicker, S R; Doriese, W Bertrand; Dunner, R; Essinger-Hileman, T; Fisher, R P; Fowler, J W; Hajian, A; Halpern, M; Hasselfield, M; Hernandez-Monteagudo, C; Hilton, G C; Hilton, M; Hincks, A D; Huffenberger, K M; Hughes, D H; Hughes, J P; Infante, L; Irwin, K D; Juin, J B; Kaul, M; Klein, J; Kosowsky, A; Lau, J M; Limon, M; Lin, Y-T; Lupton, R H; Marriage, T A; Marsden, D; Mauskopf, P; Menanteau, F; Moodley, K; Moseley, H; Netterfield, C B; Niemack, M D; Nolta, M R; Page, L A; Parker, L; Partridge, B; Reid, B; Sehgal, N; Sherwin, B; Spergel, D N; Staggs, S T; Swetz, D S; Switzer, E R; Thornton, R; Trac, H; Tucker, C; Warne, R; Wollack, E; Zhao, Y

    2010-01-01

    We present cosmological parameters derived from the angular power spectrum of the cosmic microwave background (CMB) radiation observed at 148 GHz and 218 GHz over 296 deg^2 with the Atacama Cosmology Telescope (ACT) during its 2008 season. ACT measures fluctuations at scales 500

  1. Atacama Cosmology Telescope: Extragalactic Sources at 148 GHz in the 2008 Survey

    CERN Document Server

    Marriage, T A; Lin, Y -T; Marsden, D; Nolta, M R; Partridge, B; Ade, P A R; Aguirre, P; Amiri, M; Appel, J W; Barrientos, L F; Battistelli, E S; Bond, J R; Brown, B; Burger, B; Chervenak, J; Das, S; Devlin, M J; Dicker, S R; Doriese, W B; Dunkley, J; Dunner, R; Essinger-Hileman, T; Fisher, R P; Fowler, J W; Hajian, A; Halpern, M; Hasselfield, M; Hernandez-Monteagudo, C; Hilton, G C; Hilton, M; Hincks, A D; Hlozek, R; Huffenberger, K M; Hughes, D H; Hughes, J P; Infante, L; Irwin, K D; Kaul, M; Klein, J; Kosowsky, A; Lau, J M; Limon, M; Lupton, R H; Martocci, K; Mauskopf, P; Menanteau, F; Moodley, K; Moseley, H; Netterfield, C B; Niemack, M D; Page, L A; Parker, L; Quintana, H; Reid, B; Sehgal, N; Sherwin, B D; Sievers, J; Spergel, D N; Staggs, S T; Swetz, D S; Switzer, E R; Thornton, R; Trac, H; Tucker, C; Warne, R; Wilson, G; Wollack, E; Zhao, Y

    2010-01-01

    We report on extragalactic sources detected in a 455 square-degree map of the southern sky made with data at a frequency of 148 GHz from the Atacama Cosmology Telescope 2008 observing season. We provide a catalog of 157 sources with flux densities spanning two orders of magnitude: from 15 to 1500 mJy. Comparison to other catalogs shows that 98% of the ACT detections correspond to sources detected at lower radio frequencies. Three of the sources appear to be associated with the brightest cluster galaxies of low redshift X-ray selected galaxy clusters. Estimates of the radio to mm-wave spectral indices and differential counts of the sources further bolster the hypothesis that they are nearly all radio sources, and that their emission is not dominated by re-emission from warm dust. In a bright (>50 mJy) 148 GHz-selected sample with complete cross-identifications from the Australia Telescope 20 GHz survey, we observe an average steepening of the spectra between 5, 20, and 148 GHz with median spectral indices of $...

  2. The Atacama Cosmology Telescope: Cosmology from Galaxy Clusters Detected via the Sunyaev-Zel'dovich Effect

    CERN Document Server

    Sehgal, Neelima; Acquaviva, Viviana; Ade, Peter A R; Aguirre, Paula; Amiri, Mandana; Appel, John W; Barrientos, L Felipe; Battistelli, Elia S; Bond, J Richard; Brown, Ben; Burger, Bryce; Chervenak, Jay; Das, Sudeep; Devlin, Mark J; Dicker, Simon R; Doriese, W Bertrand; Dunkley, Joanna; Dünner, Rolando; Essinger-Hileman, Thomas; Fisher, Ryan P; Fowler, Joseph W; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hernández-Monteagudo, Carlos; Hilton, Gene C; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Holtz, David; Huffenberger, Kevin M; Hughes, David H; Hughes, John P; Infante, Leopoldo; Irwin, Kent D; Jones, Andrew; Juin, Jean Baptiste; Klein, Jeff; Kosowsky, Arthur; Lau, Judy M; Limon, Michele; Lin, Yen-Ting; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Martocci, Krista; Mauskopf, Phil; Menanteau, Felipe; Moodley, Kavilan; Moseley, Harvey; Netterfield, Calvin B; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Partridge, Bruce; Reid, Beth; Sherwin, Blake D; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Tucker, Carole; Warne, Ryan; Wollack, Ed; Zhao, Yue

    2010-01-01

    We present constraints on cosmological parameters based on a sample of Sunyaev-Zel'dovich-selected galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of 9 optically-confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 square degrees of sky surveyed during 2008 at 148 GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a 4-parameter fit. Marginalizing over the values of the parameters in this fit with conservative priors gives sigma_8 = 0.851 +/- 0.115 and w = -1.14 +/- 0.35 for a spatially-flat wCDM cosmological model with WMAP 7-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP 7-year constraints alone. Fixing the scaling relation between cluste...

  3. Atacama Fault System (Chile), Acquried With the Modular Airborne Camera System (MACS)

    Science.gov (United States)

    Zielke, O.; Victor, P.; Oncken, O.; Bucher, T. U.; Lehmann, F.

    2011-12-01

    A primary step towards assessing time and size of future earthquakes is the identification of earthquake recurrence patterns in the existing seismic record. Geologic and geomorphic data are commonly analyzed for this purpose, reasoned by the lack of sufficiently long historical or instrumental seismic data sets. Until recently, those geomorphic data sets encompassed field observation, local total station surveys, and aerial photography. Over the last decade, LiDAR-based high-resolution topographic data sets became an additional powerful mean, contributing distinctly to a better understanding of earthquake rupture characteristics (e.g., single-event along-fault slip distribution, along-fault slip accumulation pattern) and their relation to fault geometric complexities. Typical shot densities of such data sets (e.g., airborne-LiDAR data along the San Andreas Fault) permit generation of digital elevation models (DEM) with Atacama fault system near Antofagasta, Chile. Data were acquired with Modular Airborne Camera System (MACS) - developed by the DLR (German Aerospace Center) in Berlin, Germany. The photogrammetrically derived DEM and True Ortho Images with fault zone and earthquake rupture characterization at unprecedented detail. Compared to typical LiDAR-DEM, ground resolution is increased by an order of magnitude while the spatial extend of these data set is essentially the same. Here, we present examples of the <5cm resolution data set (DEM and visual results) and further explore resolution capabilities and potential with regards to the aforementioned tectono-geomorphic questions.

  4. Triassic alluvial braidplain and braided river deposits of the La Ternera Formation, Atacama region, northern Chile

    Science.gov (United States)

    Bell, C. M.; Suárez, M.

    1995-01-01

    The La Ternera Formation is a thick (>2,100 m) succession of terrigenous clastic sediments, with andesitic and basaltic intercalations, exposed in the Quebrada de Paipote area of the Atacama Region, northern Chile. The strata were deposited in an active rift basin during Late Triassic to (?) Early Jurassic times. The lower 1,000 m of the studied elastic succession comprises pebbly granule paraconglomerates, unconformably overlying Upper Paleozoic sedimentary successions, volcanics, and granitoids. These sediments were derived from the east and are interpreted as braid-plain deposits. The upper 800 m of the succession comprises interbedded orthoconglomerates, sandstones and mudstones. Abundant plant fossils include trees in growth position and carbonaceous horizons. Small scale depositional cycles were the product of migrating braided-river channel systems. Larger scale successions resulted from tectonic uplift. The sediments of the La Ternera Formation were derived predominantly from a tectonically uplifted area of Upper Paleozoic acidic volcanic and plutonic rocks (Pantanoso Formation, Choiyoi Group). Active uplift on the eastern margin of the sedimentary basin probably occurred along north-south trending faults. Continued subsidence of the basin resulted in a Sinemurian to Bajocian marine transgression. Occurrences of Triassic andesitic and basaltic volcanic rocks both to the west and the east of the La Ternera formation suggest deposition in an intea-volcanic graben or half-graben.

  5. The Atacama Cosmology Telescope (ACT): Beam Profiles and First SZ Cluster Maps

    Science.gov (United States)

    Hincks, A. D.; Acquaviva, V.; Ade, P. A.; Aguirre, P.; Amiri, M.; Appel, J. W.; Barrientos, L. F.; Battistelli, E. S.; Bond, J. R.; Brown, B.; Burger, B.; Chervenak, J.; Das, S.; Devlin, M. J.; Dicker, S. R.; Doriese, W. B.; Dunkley, J.; Duenner, R.; Essinger-Hileman, T.; Fisher, R. P.; Fowler, J. W.; Hajian, A.; Halpern, M.; Hasselfield, M.; Wollack, Ed

    2010-01-01

    The Atacama Cosmology Telescope (ACT) is currently observing the cosmic microwave background with arcminute resolution at 148 GHz, 218 GHz, and 277 GHz, In this paper, we present ACT's first results. Data have been analyzed using a maximum-likelihood map-making method which uses B-splines to model and remove the atmospheric signal. It has been used to make high-precision beam maps from which we determine the experiment's window functions, This beam information directly impacts all subsequent analyses of the data. We also used the method to map a sample of galaxy clusters via the Sunyaev-Ze1'dovich (SZ) effect, and show five clusters previously detected with X-ray or SZ observations, We provide integrated Compton-y measurements for each cluster. Of particular interest is our detection of the z = 0.44 component of A3128 and our current non-detection of the low-redshift part, providing strong evidence that the further cluster is more massive as suggested by X-ray measurements. This is a compelling example of the redshift-independent mass selection of the SZ effect.

  6. Braided rivers, lakes and sabkhas of the upper Triassic Cifuncho formation, Atacama region, Chile

    Science.gov (United States)

    Suárez, M.; Bell, C. M.

    1994-01-01

    A 1,000-m-thickness of Upper Triassic (to possibly Hettangian) sediments of the Cifuncho Formation are exposed in the coastal Cordillera of the Atacama Region, Chile. These coarse-grained clastic terrigenous strata are interpreted as the deposits of braided rivers, ephemeral lakes, sabkhas and volcaniclastic alluvial fans. They include conglomerates, pebbly sandstones, fine to medium-grained sandstones and thin, finely-laminated limestones. Halite hopper-casts are abundant in sandstones near the top of the section. Approximately 90% of the clastic detritus was derived from an upper Paleozoic metasedimentary accretionary complex located to the west. Andesitic debris flow and pyroclastic flow deposits occur near the base of the sequence. Isolated tuff intercalations and an ignimbritic lava flow occur higher in the section. The great thickness of coarse-grained and ill-sorted clastic sediments suggests deposition in an actively subsiding basin, probably a graben, adjacent to rising highlands. Overlying Hettangian-Sinemurian marine sediments were deposited by a transgression which occurred during a world-wide lowstand. This suggests that thermal subsidence followed the Triassic rifting.

  7. The Atacama Cosmology Telescope: Beam Measurements and the Microwave Brightness Temperatures of Uranus and Saturn

    CERN Document Server

    Hasselfield, Matthew; Bond, J Richard; Das, Sudeep; Devlin, Mark J; Dunkley, Joanna; Dunner, Rolando; Fowler, Joseph W; Gallardo, Patricio; Gralla, Megan B; Hajian, Amir; Halpern, Mark; Hincks, Adam D; Marriage, Tobias A; Marsden, Danica; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Partridge, Bruce; Schmitt, Benjamin L; Sehgal, Neelima; Sievers, Jon; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Wollack, Edward J

    2013-01-01

    We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilo-pixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty, to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final CMB survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the ...

  8. The Atacama Cosmology Telescope: Temperature and Gravitational Lensing Power Spectrum Measurements from Three Seasons of Data

    CERN Document Server

    Das, Sudeep; Nolta, Michael R; Addison, Graeme E; Battistelli, Elia S; Bond, J Richard; Calabrese, Erminia; Devlin, Devin Crichton Mark J; Dicker, Simon; Dunkley, Joanna; Dünner, Rolando; Fowler, Joseph W; Gralla, Megan; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Huffenberger, Kevin M; Hughes, John P; Irwin, Kent D; Kosowsky, Arthur; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D; Page, Lyman A; Partridge, Bruce; Reese, Erik D; Schmitt, Benjamin L; Sehgal, Neelima; Sherwin, Blake D; Sievers, Jonathan L; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Trac, Hy; Wollack, Ed

    2013-01-01

    We present the temperature power spectra of the cosmic microwave background (CMB) derived from the three seasons of data from the Atacama Cosmology Telescope (ACT) at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. We detect and correct for contamination due to the Galactic cirrus in our equatorial maps. We present the results of a number of tests for possible systematic error and conclude that any effects are not significant compared to the statistical errors we quote. Where they overlap, we cross-correlate the ACT and the South Pole Telescope (SPT) maps and show they are consistent. The measurements of higher-order peaks in the CMB power spectrum provide an additional test of the Lambda CDM cosmological model, and help constrain extensions beyond the standard model. The small angular scale power spectrum also provides constraining power on the Sunyaev-Zel'dovich effects and extragalactic foregrounds. We also present a measurement of the CMB gravitational lensing conver...

  9. Cornell Caltech Atacama Telescope (CCAT): a 25 m aperture telescope above 5000 m altitude

    CERN Document Server

    Sebring, T A; Radford, S; Zmuidzinas, J; Sebring, Thomas A.; Giovanelli, Riccardo; Radford, Simon; Zmuidzinas, Jonas

    2006-01-01

    Cornell, California Institute of Technology (Caltech), and Jet Propulsion Lab (JPL) have joined together to study development of a 25 meter sub-millimeter telescope (CCAT) on a high peak in the Atacama region of northern Chile, where the atmosphere is so dry as to permit observation at wavelengths as short as 200 micron. The telescope is designed to deliver high efficiency images at that wavelength with a total 1/2 wavefront error of about 10 microns. With a 20 arc min field of view, CCAT will be able to accommodate large format bolometer arrays and will excel at carrying out surveys as well as resolving structures to the 2 arc sec. resolution level. The telescope will be an ideal complement to ALMA. Initial instrumentation will include both a wide field bolometer camera and a medium resolution spectrograph. Studies of the major telescope subsystems have been performed as part of an initial Feasibility Concept Study. Novel aspects of the telescope design include kinematic mounting and active positioning of pr...

  10. The DataCapturer component for the Atacama Large Millimeter Array

    Science.gov (United States)

    Hafok, H.; Caillat, M.; McMullin, J.

    2006-07-01

    We describe the data capture process (DataCapturer) for the Atacama Large Millimeter Array (ALMA) control software. This is implemented as a JAVA-based CORBA-component running in the framework of the ALMA Common Software (ACS). During an observation, data (e.g., visibilities) and meta-data (e.g., information describing the state of the hardware, antennas, source, etc) flow through the control system and need to be recorded. All meta-data flows through the DataCapturer component where it is collected and organized as an ALMA Science Data model (ASDM) dataset and then written to the ALMA archive data base. DataCapturer is the interface between the telescope and the science domain. In the telescope domain it gets raw information from the control system and the correlator and produces science formated data for ALMA subsystems in the science domain. ASDM data is delivered to the Quicklook display sub-system and the telescope calibration sub-system of the ALMA Software. The final dataset is stored at the end of a sequence of observations (combined in an execution block) in the ALMA science archive.

  11. Kilopixel Pop-Up Bolometer Arrays for the Atacama Cosmology Telescope

    Science.gov (United States)

    Chervenak, J. A.; Wollack, E.; Henry, R.; Moseley, S. H.; Niemack, M.; Staggs, S.; Page, L.; Doriese, R.; Hilton, G. c.; Irwin, K. D.

    2007-01-01

    The recently deployed Atacama Cosmology Telescope (ACT) anticipates first light on its kilopixel array of close-packed transition-edge-sensor bolometers in November of 2007. The instrument will represent a full implementation of the next-generation, large format arrays for millimeter wave astronomy that use superconducting electronics and detectors. Achieving the practical construction of such an array is a significant step toward producing advanced detector arrays for future SOFIA instruments. We review the design considerations for the detector array produced for the ACT instrument. The first light imager consists of 32 separately instrumented 32-channel pop-up bolometer arrays (to create a 32x32 filled array of mm-wave sensors). Each array is instrumented with a 32-channel bias resistor array, Nyquist filter array, and time-division SQUID multiplexer. Each component needed to be produced in relatively large quantities with suitable uniformity to meet tolerances for array operation. An optical design was chosen to maximize absorption at the focal plane while mitigating reflections and stray light. The pop-up geometry (previously implemented with semiconducting detectors and readout on the SHARC II and HAWC instruments) enabled straightforward interface of the superconducting bias and readout circuit with the 2D array of superconducting bolometers. The array construction program balanced fabrication challenges with assembly challenges to deliver the instrument in a timely fashion. We present some of the results of the array build and characterization of its performance.

  12. Gopherus agassizii (desert tortoise). Burrow collapse

    Science.gov (United States)

    Loughran, Caleb L.; Ennen, Joshua; Lovich, Jeffrey E.

    2011-01-01

    In the deserts of the southwestern U.S., burrows are utilized by the Desert Tortoise to escape environmental extremes (reviewed by Ernst and Lovich 2009. Turtles of the United States and Canada. 2nd ed. Johns Hopkins Univ. Press, Baltimore, Maryland. 827 pp.). However, the potential for mortality through burrow collapse and entrapment is poorly documented. Nicholson and Humphreys (1981. Proceedings of the Desert Tortoise Council, pp. 163−194) suggested that collapse due to livestock trampling may cause mortality. In addition, Lovich et al. (2011. Chelon. Cons. Biol. 10[1]:124–129) documented a Desert Tortoise that used a steel culvert as a burrow surrogate. The culvert filled completely with sediment following a significant rain event, entombing the animal and ultimately resulting in its death. We note that this mortality was associated with an anthropogenic structure; because tortoises are prodigious diggers, one might hypothesize that they have the ability to dig out of collapsed natural burrows in most situations. Circumstances described here presented us with an opportunity to test this hypothesis.

  13. Spectral reflectance in the Tunisian desert.

    NARCIS (Netherlands)

    Epema, G.F.

    1992-01-01

    .Satellites provide the possibility to give a synoptical view of the earth surface at regular time intervals. Satellites operating in the optical wavelengths have however as disadvantage that monitoring of the surface characteristics becomes impossible as soon as clouds are present. Deserts and dese

  14. Reclaiming freshwater sustainability in the Cadillac Desert

    Science.gov (United States)

    Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H.W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

    2010-01-01

    Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%.

  15. Microflora in soils of desert regions

    Science.gov (United States)

    Cameron, R. E.

    1970-01-01

    Desert soil samples, collected using aseptic techniques, are low in organic matter and cation exchange capacity. Aerobic and microaerophilic bacteria are most abundant, next are algae and molds. Chemical and physical properties are determined by standard procedures, including the Kjeldahl method and the use of Munsell soil color charts.

  16. Habitat selection by juvenile Mojave Desert tortoises

    Science.gov (United States)

    Todd, Brian D; Halstead, Brian J.; Chiquoine, Lindsay P.; Peaden, J. Mark; Buhlmann, Kurt A.; Tuberville, Tracey D.; Nafus, Melia G.

    2016-01-01

    Growing pressure to develop public lands for renewable energy production places several protected species at increased risk of habitat loss. One example is the Mojave desert tortoise (Gopherus agassizii), a species often at the center of conflicts over public land development. For this species and others on public lands, a better understanding of their habitat needs can help minimize negative impacts and facilitate protection or restoration of habitat. We used radio-telemetry to track 46 neonate and juvenile tortoises in the Eastern Mojave Desert, California, USA, to quantify habitat at tortoise locations and paired random points to assess habitat selection. Tortoise locations near burrows were more likely to be under canopy cover and had greater coverage of perennial plants (especially creosote [Larrea tridentata]), more coverage by washes, a greater number of small-mammal burrows, and fewer white bursage (Ambrosia dumosa) than random points. Active tortoise locations away from burrows were closer to washes and perennial plants than were random points. Our results can help planners locate juvenile tortoises and avoid impacts to habitat critical for this life stage. Additionally, our results provide targets for habitat protection and restoration and suggest that diverse and abundant small-mammal populations and the availability of creosote bush are vital for juvenile desert tortoises in the Eastern Mojave Desert.

  17. Wood decay in desert riverine environments

    Science.gov (United States)

    Andersen, Douglas; Stricker, Craig A.; Nelson, S. Mark

    2016-01-01

    Floodplain forests and the woody debris they produce are major components of riverine ecosystems in many arid and semiarid regions (drylands). We monitored breakdown and nitrogen dynamics in wood and bark from a native riparian tree, Fremont cottonwood (Populus deltoides subsp. wislizeni), along four North American desert streams. We placed locally-obtained, fresh, coarse material [disks or cylinders (∼500–2000 cm3)] along two cold-desert and two warm-desert rivers in the Colorado River Basin. Material was placed in both floodplain and aquatic environments, and left in situ for up to 12 years. We tested the hypothesis that breakdown would be fastest in relatively warm and moist aerobic environments by comparing the time required for 50% loss of initial ash-free dry matter (T50) calculated using exponential decay models incorporating a lag term. In cold-desert sites (Green and Yampa rivers, Colorado), disks of wood with bark attached exposed for up to 12 years in locations rarely inundated lost mass at a slower rate (T50 = 34 yr) than in locations inundated during most spring floods (T50 = 12 yr). At the latter locations, bark alone loss mass at a rate initially similar to whole disks (T50 = 13 yr), but which subsequently slowed. In warm-desert sites monitored for 3 years, cylinders of wood with bark removed lost mass very slowly (T50 = 60 yr) at a location never inundated (Bill Williams River, Arizona), whereas decay rate varied among aquatic locations (T50 = 20 yr in Bill Williams River; T50 = 3 yr in Las Vegas Wash, an effluent-dominated stream warmed by treated wastewater inflows). Invertebrates had a minor role in wood breakdown except at in-stream locations in Las Vegas Wash. The presence and form of change in nitrogen content during exposure varied among riverine environments. Our results suggest woody debris breakdown in desert riverine ecosystems is primarily a microbial process with rates determined by landscape position

  18. Systematics of Natural Perchlorate in Precipitation, Soils, and Plants at the Amargosa Desert Research Site, Nye County, Nevada

    Science.gov (United States)

    Andraski, B. J.; Stonestrom, D. A.; Jackson, W. A.; Rajagopalan, S.; Taylor, E. M.

    2007-12-01

    Naturally occurring perchlorate is known to be associated with nitrate deposits of the hyperarid Atacama Desert in Chile, and recent large-scale sampling has identified a substantial reservoir (up to 1 kg/ha) of natural perchlorate in diverse unsaturated zones of the arid and semiarid Southwestern United States (Rao et al., 2007, ES&T, DOI: 10.1021/es062853i). The objective of the Amargosa Desert work is to develop a better understanding of the deposition, accumulation, and biological cycling of perchlorate in arid environments. Occurrence of perchlorate was evaluated by sampling shallow soil profiles up to 3 m in depth at four different locations and at two different time periods, and by sampling dominant plant species growing near the subsurface profiles. Deposition of perchlorate was evaluated by analyzing both bulk deposition (precipitation plus dry fall, collected under oil) collected on site and wet deposition samples collected by the National Atmospheric Deposition program at a nearby site. Soil samples and atmospheric-deposition samples were tested for both perchlorate (ClO4- ) and major anions. Perchlorate concentrations (0.2-20 µg/kg) were variable with depth in soil profiles and generally correlated most highly with chloride (Cl-) and nitrate (NO3-), although the intensity of these relations differed among profiles. Plant concentrations were generally above 1 mg/kg, suggesting ClO4- accumulation. Concentrations of ClO4- were generally much greater in total deposition than wet deposition samples, indicating a substantial dryfall component of meteoric deposition. This presentation will present the mass distribution and variability of perchlorate in bulk deposition, soils, and plants. Reasons for observed relations between subsurface concentrations of perchlorate and other anions will be explored.

  19. Detecting leaf pulvinar movements on NDVI time series of desert trees: a new approach for water stress detection.

    Directory of Open Access Journals (Sweden)

    Roberto O Chávez

    Full Text Available Heliotropic leaf movement or leaf 'solar tracking' occurs for a wide variety of plants, including many desert species and some crops. This has an important effect on the canopy spectral reflectance as measured from satellites. For this reason, monitoring systems based on spectral vegetation indices, such as the normalized difference vegetation index (NDVI, should account for heliotropic movements when evaluating the health condition of such species. In the hyper-arid Atacama Desert, Northern Chile, we studied seasonal and diurnal variations of MODIS and Landsat NDVI time series of plantation stands of the endemic species Prosopis tamarugo Phil., subject to different levels of groundwater depletion. As solar irradiation increased during the day and also during the summer, the paraheliotropic leaves of Tamarugo moved to an erectophile position (parallel to the sun rays making the NDVI signal to drop. This way, Tamarugo stands with no water stress showed a positive NDVI difference between morning and midday (ΔNDVI mo-mi and between winter and summer (ΔNDVI W-S. In this paper, we showed that the ΔNDVI mo-mi of Tamarugo stands can be detected using MODIS Terra and Aqua images, and the ΔNDVI W-S using Landsat or MODIS Terra images. Because pulvinar movement is triggered by changes in cell turgor, the effects of water stress caused by groundwater depletion can be assessed and monitored using ΔNDVI mo-mi and ΔNDVI W-S. For an 11-year time series without rainfall events, Landsat ΔNDVI W-S of Tamarugo stands showed a positive linear relationship with cumulative groundwater depletion. We conclude that both ΔNDVI mo-mi and ΔNDVI W-S have potential to detect early water stress of paraheliotropic vegetation.

  20. Assessing Water Stress of Desert Tamarugo Trees Using in situ Data and Very High Spatial Resolution Remote Sensing

    Directory of Open Access Journals (Sweden)

    Edmundo Acevedo

    2013-10-01

    Full Text Available The hyper-arid Atacama Desert is one of the most extreme environments for life and only few species have evolved to survive its aridness. One such species is the tree Prosopis tamarugo Phil. Because Tamarugo completely depends on groundwater, it is being threatened by the high water demand from the Chilean mining industry and the human consumption. In this paper, we identified the most important biophysical variables to assess the water status of Tamarugo trees and tested the potential of WorldView2 satellite images to retrieve these variables. We propose green canopy fraction (GCF and green drip line leaf area index (DLLAIgreen as best variables and a value of 0.25 GCF as a critical threshold for Tamarugo survival. Using the WorldView2 spectral bands and an object-based image analysis, we showed that the NDVI and the Red-edge Chlorophyll Index (CIRed-edge have good potential to retrieve GCF and DLLAIgreen. The NDVI performed best for DLLAIgreen (RMSE = 0.4 while the CIRed-edge was best for GCF (RMSE = 0.1. However, both indices were affected by Tamarugo leaf movements (leaves avoid facing direct solar radiation at the hottest time of the day. Thus, monitoring systems based on these indices should consider the time of the day and the season of the year at which the satellite images are acquired.

  1. West Coast Regional Office Permits

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA Fisheries implemented a license limitation program for the trawl and fixed gear sectors of Pacific Coast commercial groundfish fishery on January 1, 1993. The...

  2. Paleomagnetic and structural constraints on rotations in the North Chilean coast ranges

    Science.gov (United States)

    Forsythe, R.; Chisholm, L.

    1994-10-01

    Paleomagnetic analysis of seventy-six samples from six sites in the Jurassic to Cretaceous plutons (radiometric ages from 157 to 128 Ma) of the Coastal Cordillera of northern Chile yielded stable remanent magnetization directions. The plutons record both a normal and a reversed characteristics direction. The mean normal direction has a declination of 3.4° an inclination of -38.5°, and an alpha 95 of 10.5°. The mean reversed direction has a declination of 207.8°, an inclination of 33.8°, and an alpha 95 of 10.8°. Paleopoles calculated from these mean and latitude=63.5° S, longitude=191.9° E respectively. In comparison to an APW path, the reversed pole indicates a clockwise rotation of approximately 28°, similar to other regional results, whereas the normal pole is concordant with the present day magnetic field. These results, in and of themselves, could support oroclinal bending or local block rotations. However arrays of secondary faults to the Atacama fault system in the sampling area show characteristic spacings, orientations, and displacements. Restoration of displacements results in a 31° clockwise rotation of fault blocks; essentially removing the observed paleomagnetic discordance. Thus, structural data confirms the local block rotation model. The existence of clockwise discordant paleomagnetic data within the sinistral (counterclockwise) Atacama Fault zone (AFZ) underscores the ambiguity of using the sense of rotation to infer the sense of motion on the larger shear zone. Age constraints for motions along the AFZ suggest that these rotations were completed in the Early Cretaceous; essentially coeval with magmatic activity within the Coast Ranges, and underscores the magmatic arc, rather than forearc, setting for this tectonic event.

  3. Weathering and solute transport to the Salar de Atacama, northern Chile

    Science.gov (United States)

    Hynek, S. A.; Munk, L. A.; Boutt, D. F.

    2013-12-01

    The Salar de Atacama is situated in a tectonic basin on the Tropic of Capricorn, adjacent to the Central Andean Volcanic Zone in hyper-arid northern Chile. This basin has been hydrographically closed for most, if not all, of the Cenozoic. Since the late Miocene, chemical sediment (primarily halite, but also sulphate) and Na-Cl brines have accumulated. The volume of these deposits provides a constraint on long term average solute fluxes. We have undertaken an extensive multiple isotope study of surface and shallow groundwater in the basin to constrain processes and pathways affecting solute fluxes to the basin. By comparing these inflow waters to brackish waters and brines, we are able to place constraints on modern weathering with the ultimate goal of comparing it to longer term fluxes estimated from the geologic record. The volcanic arc and extensive large volume silicic magma chambers provide potential sources of solutes to the basin which are not a direct result of surficial weathering (hydrothermal waters/magmatic brines). For most freshwater, this possibility is ruled out. Oxygen and hydrogen isotopes in water provide no strong evidence for high temperature water-rock interaction. Further, the isotopic composition of helium dissolved in groundwater demonstrates that most groundwater carries an atmospheric signal (air saturated water), though some evidence for the influence of magmatic brines is found in shallow groundwater with high concentrations of helium-3, methane, and carbon dioxide. The strontium isotopic composition of waters and brines exhibits geographic variation that is related to at least four sources; 1) weathering of Andean volcanic arc along the eastern margin of the basin (87/86 ratios ~0.708), 2) thermal waters sourced in the northern headwaters of the Río San Pedro and 3) high calcium weathering fluxes from the Cordón de Lila on the southern margin of the basin, both of which have more radiogenic 87/86 ratios than the Andean volcanic arc

  4. The Atacama Cosmology Telescope: CMB polarization at 200 < ℓ < 9000

    Energy Technology Data Exchange (ETDEWEB)

    Naess, Sigurd; Allison, Rupert; Calabrese, Erminia [Sub-Department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Hasselfield, Matthew [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); McMahon, Jeff; Coughlin, Kevin; Datta, Rahul [Department of Physics, University of Michigan, Ann Arbor 48103 (United States); Niemack, Michael D.; De Bernardis, Francesco [Department of Physics, Cornell University, Ithaca, NY 14853 (United States); Addison, Graeme E.; Amiri, Mandana [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Ade, Peter A. R. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff, Wales CF24 3AA (United Kingdom); Battaglia, Nick [McWilliams Center for Cosmology, Carnegie Mellon University, Department of Physics, 5000 Forbes Ave., Pittsburgh PA 15213 (United States); Beall, James A.; Britton, Joe; Cho, Hsiao-mei [NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States); Bond, J Richard [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Crichton, Devin [Dept. of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Das, Sudeep [Department of High Energy Physics, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL 60439 (United States); Devlin, Mark J., E-mail: sigurd.naess@astro.ox.ac.uk [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); and others

    2014-10-01

    We report on measurements of the cosmic microwave background (CMB) and celestial polarization at 146 GHz made with the Atacama Cosmology Telescope Polarimeter (ACTPol) in its first three months of observing. Four regions of sky covering a total of 270 square degrees were mapped with an angular resolution of 1.3'. The map noise levels in the four regions are between 11 and 17 μK-arcmin. We present TT, TE, EE, TB, EB, and BB power spectra from three of these regions. The observed E-mode polarization power spectrum, displaying six acoustic peaks in the range 200 < ℓ < 3000, is an excellent fit to the prediction of the best-fit cosmological models from WMAP9+ACT and Planck data. The polarization power spectrum, which mainly reflects primordial plasma velocity perturbations, provides an independent determination of cosmological parameters consistent with those based on the temperature power spectrum, which results mostly from primordial density perturbations. We find that without masking any point sources in the EE data at ℓ < 9000, the Poisson tail of the EE power spectrum due to polarized point sources has an amplitude less than 2.4 μ {sup 2} at ℓ = 3000 at 95% confidence. Finally, we report that the Crab Nebula, an important polarization calibration source at microwave frequencies, has 8.7% polarization with an angle of 150.7{sup o} ± 0.6{sup o} when smoothed with a 5' Gaussian beam.

  5. The Atacama Cosmology Telescope: likelihood for small-scale CMB data

    Energy Technology Data Exchange (ETDEWEB)

    Dunkley, J.; Calabrese, E. [Sub-department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Sievers, J. [Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States); Addison, G.E.; Halpern, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada V6T 1Z4 (Canada); Battaglia, N. [McWilliams Center for Cosmology, Wean Hall, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh PA 15213 (United States); Battistelli, E.S. [Department of Physics, University of Rome ' La Sapienza' , Piazzale Aldo Moro 5, I-00185 Rome (Italy); Bond, J.R.; Hajian, A.; Hincks, A.D. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON, Canada M5S 3H8 (Canada); Das, S. [High Energy Physics Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont IL 60439 (United States); Devlin, M.J. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Dünner, R. [Departamento de Astronomía y Astrofísica, Pontificía Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Fowler, J.W.; Irwin, K.D. [NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States); Gralla, M. [Dept. of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Hasselfield, M.; Hlozek, R. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Hughes, J.P. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8019 (United States); Kosowsky, A., E-mail: j.dunkley@physics.ox.ac.uk [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); and others

    2013-07-01

    The Atacama Cosmology Telescope has measured the angular power spectra of microwave fluctuations to arcminute scales at frequencies of 148 and 218 GHz, from three seasons of data. At small scales the fluctuations in the primordial Cosmic Microwave Background (CMB) become increasingly obscured by extragalactic foregounds and secondary CMB signals. We present results from a nine-parameter model describing these secondary effects, including the thermal and kinematic Sunyaev-Zel'dovich (tSZ and kSZ) power; the clustered and Poisson-like power from Cosmic Infrared Background (CIB) sources, and their frequency scaling; the tSZ-CIB correlation coefficient; the extragalactic radio source power; and thermal dust emission from Galactic cirrus in two different regions of the sky. In order to extract cosmological parameters, we describe a likelihood function for the ACT data, fitting this model to the multi-frequency spectra in the multipole range 500 < l < 10000. We extend the likelihood to include spectra from the South Pole Telescope at frequencies of 95, 150, and 220 GHz. Accounting for different radio source levels and Galactic cirrus emission, the same model provides an excellent fit to both datasets simultaneously, with χ{sup 2}/dof= 675/697 for ACT, and 96/107 for SPT. We then use the multi-frequency likelihood to estimate the CMB power spectrum from ACT in bandpowers, marginalizing over the secondary parameters. This provides a simplified 'CMB-only' likelihood in the range 500 < l < 3500 for use in cosmological parameter estimation.

  6. The Atacama Cosmology Telescope: Cosmology from Galaxy Clusters Detected Via the Sunyaev-Zel'dovich Effect

    Science.gov (United States)

    Sehgal, Neelima; Trac, Hy; Acquaviva, Viviana; Ade, Peter A. R.; Aguirre, Paula; Amiri, Mandana; Appel, John W.; Barrientos, L. Felipe; Battistelli, Elia S.; Bond, J. Richard; Brown, Ben; Burger, Bryce; Chervenak, Jay; Das, Sudeep; Devlin, Mark J.; Dicker, Simon R.; Doriese, W. Bertrand; Dunkley, Joanna; Duenner, Rolando; Essinger-Hileman, Thomas; Fisher, Ryan P.; Fowler, Joseph W.; Hajian, Amir; Halpern, Mark; Wollack, Ed

    2010-01-01

    We present constraints on cosmological parameters based on a sample of Sunyaev-Zel'dovich-selected galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of 9 optically-confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 square degrees of sky surveyed during 2008 at 148 GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a 4-parameter fit. Marginalizing over the values of the parameters in this fit with conservative priors gives (sigma)8 = 0.851 +/- 0.115 and w = -1.14 +/- 0.35 for a spatially-flat wCDM cosmological model with WMAP 7-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP 7-year constraints alone. Fixing the scaling relation between cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find (sigma)8 + 0.821 +/- 0.044 and w = -1.05 +/- 0.20. These results are consistent with constraints from WMAP 7 plus baryon acoustic oscillations plus type Ia supernova which give (sigma)8 = 0.802 +/- 0.038 and w = -0.98 +/- 0.053. A stacking analysis of the clusters in this sample compared to clusters simulated assuming the fiducial model also shows good agreement. These results suggest that, given the sample of clusters used here, both the astrophysics of massive clusters and the cosmological parameters derived from them are broadly consistent with current models.

  7. THE ATACAMA COSMOLOGY TELESCOPE: BEAM MEASUREMENTS AND THE MICROWAVE BRIGHTNESS TEMPERATURES OF URANUS AND SATURN

    Energy Technology Data Exchange (ETDEWEB)

    Hasselfield, Matthew [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Moodley, Kavilan [Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics, and Computer Science, University of KwaZulu-Natal, Durban 4041 (South Africa); Bond, J. Richard; Hajian, Amir; Hincks, Adam D.; Nolta, Michael R. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Das, Sudeep [High Energy Physics Division, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States); Devlin, Mark J.; Marsden, Danica; Schmitt, Benjamin L. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Dunkley, Joanna [Department of Astrophysics, Oxford University, Oxford OX1 3RH (United Kingdom); Dünner, Rolando; Gallardo, Patricio [Departamento de Astronomía y Astrofísica, Facultad de Física, Pontificía Universidad Católica, Casilla 306, Santiago 22 (Chile); Fowler, Joseph W.; Niemack, Michael D. [NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States); Gralla, Megan B.; Marriage, Tobias A. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686 (United States); Halpern, Mark [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Page, Lyman A. [Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States); Partridge, Bruce [Department of Physics and Astronomy, Haverford College, Haverford, PA 19041 (United States); and others

    2013-11-01

    We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilopixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final cosmic microwave background (CMB) survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures T{sub U}{sup 149}= 106.7 ± 2.2 K and T{sub U}{sup 219}= 100.1 ± 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of T{sub S}{sup 149}= 137.3 ± 3.2 K and T{sub S}{sup 219}= 137.3 ± 4.7 K.

  8. Solar Observations with the Atacama Large Millimeter/submillimeter Array (ALMA)

    Science.gov (United States)

    Bastian, Timothy S.

    2015-04-01

    The Atacama Large Millimeter/Submillimeter Array (ALMA) is a joint North American, European, and East Asian project that opens the mm-submm wavelength part of the electromagnetic spectrum for general astrophysical exploration, providing high-resolution imaging in frequency bands currently ranging from 84 GHz to 950 GHz (300 microns to 3 mm). Despite being a general purpose instrument, provisions have been made to enable solar observations with ALMA. Radiation emitted at ALMA wavelengths originates mostly from the chromosphere, which plays an important role in the transport of matter and energy, and the in heating the outer layers of the solar atmosphere. Despite decades of research, the solar chromosphere remains a significant challenge: both to observe, owing to the complicated formation mechanisms of currently available diagnostics; and to understand, as a result of the complex nature of the structure and dynamics of the chromosphere. ALMA has the potential to change the scene substantially as it serves as a nearly linear thermometer at high spatial and temporal resolution, enabling us to study the complex interaction of magnetic fields and shock waves and yet-to-be-discovered dynamical processes. Moreover, ALMA will play an important role in the study of energetic emissions associated with solar flares at sub-THz frequencies.In this paper we describe recent efforts to ensure that ALMA can be usefully exploited by the scientific community to address outstanding questions in solar physics. We summarize activities by the ALMA solar development team comprised of scientists from the East Asia, North America, and Europe. These activities include instrument testing, development of calibration and imaging strategies, software requirements development, and science simulations. Opportunities for the wider community to contribute to these efforts will be highlighted.

  9. Snow, the Great River, and the Desert

    Science.gov (United States)

    Rango, A.

    2005-12-01

    While many major rivers around the world originate from alpine snowpacks in mountain regions, some experience the extreme contrast of flowing through harsh desert environments downriver. One such stream is the Rio Grande which rises in the San Juan and the Sangre de Christo mountains of southern Colorado and northern New Mexico. Eventually, the snow fed Rio Grande flows through North America's largest desert, the Chihuahuan Desert in New Mexico, Texas, and Mexico, and simultaneously becomes part of the border between the United States and Mexico. As is often true, urban areas develop along the river corridors rather than in more inaccessible mountain regions. This demographic preference tends to isolate the vast majority of population in the Rio Grande, who are dependent on water for their livelihoods, from the mountain snowpacks where the flow is generated. Ironically then, snow is seldom viewed as the source of the much needed water flowing through the desert by the majority of the basin's population. In arid regions of the western U.S., water demand far exceeds the water supply, and water use is apportioned under the doctrine of prior appropriation with the oldest right getting the first use of water. The increasing population in urban areas does not usually have a right to use the water flowing through the desert unless water rights have been purchased by municipalities from the major category of water user in these basins, namely, irrigated agriculture. In the entire Rio Grande basin, irrigation makes up 80% of the consumptive use of water. Additionally, basin compacts and international treaties apportion water between states and countries. Because these formal agreements were based on above average runoff years, there is little flexibility in changing the use of water, particularly in dry to normal runoff years. Most of the older water rights in the Rio Grande, especially the upper basin, are supplied by snowmelt. This leaves the lower basin to depend upon

  10. Examining the life history of an individual from Solcor 3, San Pedro de Atacama: Combining bioarchaeology and archaeological chemistry

    International Nuclear Information System (INIS)

    Detailed life history information using multiple lines of evidence including the identification of geographic origins, health, and body use indicators, can be used to elucidate the complex process of acculturation in the San Pedro de Atacama oases of northern Chile during the Middle Horizon. This paper presents the results of bioarchaeological and archaeological chemical analyses of the skeletal remains of an adult male (tomb 50, catalog number 1948) from the cemetery of Solcor 3 (ca. AD 500-900). Strontium isotope ratios in human tooth enamel reveal information about where a person lived during their childhood, when enamel was being formed. Individual 1948 showed strontium isotope ratios decidedly outside the range of the local San Pedro de Atacama strontium isotope signature. Given these data implying that individual 1948 was originally from elsewhere, an examination of his health status, social role, and mortuary context provides insight into the treatment of foreigners in San Pedro de Atacama. Our data support the argument that individual 1948's foreign birth did not hinder his later assimilation into Atacameno society. He was buried in a local cemetery with a typical mortuary assemblage for a male of this time and no strong evidence of possible foreign origin. Skeletal indicators of diet and activity patterns do not distinguish individual 1948 from the local population, suggesting that his lifestyle was similar to that of other Atacamenos. Therefore, our analyses suggest that individual 1948's acculturation into Atacameno society during his adult life was nearly complete and he retained little to no indication of his probable foreign birth

  11. Honduras: Caribbean Coast.

    Science.gov (United States)

    Harborne, A R; Afzal, D C; Andrews, M J

    2001-12-01

    The coast of Honduras, Central America, represents the southern end of the Mesoamerican Barrier Reef System, although its marine resources are less extensive and studied than nearby Belize and Mexico. However, the coastal zone contains mainland reef formations, mangroves, wetlands, seagrass beds and extensive fringing reefs around its offshore islands, and has a key role in the economy of the country. Like most tropical areas, this complex of benthic habitats experiences limited annual variation in climatic and oceanographic conditions but seasonal and occasional conditions, particularly coral bleaching and hurricanes, are important influences. The effects of stochastic factors on the country's coral reefs were clearly demonstrated during 1998 when Honduras experienced a major hurricane and bleaching event. Any natural or anthropogenic impacts on reef health will inevitably affect other countries in Latin America, and vice versa, since the marine resources are linked via currents and the functioning of the system transcends political boundaries. Much further work on, for example, movement of larvae and transfer of pollutants is required to delineate the full extent of these links. Anthropogenic impacts, largely driven by the increasing population and proportion of people living in coastal areas, are numerous and include key factors such as agricultural run-off, over-fishing, urban and industrial pollution (particularly sewage) and infrastructure development. Many of these threats act synergistically and, for example, poor watershed management via shifting cultivation, increases sedimentation and pesticide run-off onto coral reefs, which increases stress to corals already affected by decreasing water quality and coral bleaching. Threats from agriculture and fishing are particularly significant because of the size of both industries. The desire to generate urgently required revenue within Honduras has also led to increased tourism which provides an overarching stress

  12. Honduras: Caribbean Coast.

    Science.gov (United States)

    Harborne, A R; Afzal, D C; Andrews, M J

    2001-12-01

    The coast of Honduras, Central America, represents the southern end of the Mesoamerican Barrier Reef System, although its marine resources are less extensive and studied than nearby Belize and Mexico. However, the coastal zone contains mainland reef formations, mangroves, wetlands, seagrass beds and extensive fringing reefs around its offshore islands, and has a key role in the economy of the country. Like most tropical areas, this complex of benthic habitats experiences limited annual variation in climatic and oceanographic conditions but seasonal and occasional conditions, particularly coral bleaching and hurricanes, are important influences. The effects of stochastic factors on the country's coral reefs were clearly demonstrated during 1998 when Honduras experienced a major hurricane and bleaching event. Any natural or anthropogenic impacts on reef health will inevitably affect other countries in Latin America, and vice versa, since the marine resources are linked via currents and the functioning of the system transcends political boundaries. Much further work on, for example, movement of larvae and transfer of pollutants is required to delineate the full extent of these links. Anthropogenic impacts, largely driven by the increasing population and proportion of people living in coastal areas, are numerous and include key factors such as agricultural run-off, over-fishing, urban and industrial pollution (particularly sewage) and infrastructure development. Many of these threats act synergistically and, for example, poor watershed management via shifting cultivation, increases sedimentation and pesticide run-off onto coral reefs, which increases stress to corals already affected by decreasing water quality and coral bleaching. Threats from agriculture and fishing are particularly significant because of the size of both industries. The desire to generate urgently required revenue within Honduras has also led to increased tourism which provides an overarching stress

  13. Honduras: Caribbean Coast

    Energy Technology Data Exchange (ETDEWEB)

    Harborne, Alastair R.; Afzal, Daniel C.; Andrews, Mark J. [Coral Cay Conservation, London (United Kingdom)

    2001-07-01

    The coast of Honduras, Central America, represents the southern end of the Mesoamerican Barrier Reef System, although its marine resources are less extensive and studied than nearby Belize and Mexico. However, the coastal zone contains mainland reef formations, mangroves, wetlands, seagrass beds and extensive fringing reefs around its offshore islands, and has a key role in the economy of the country. Like most tropical areas, this complex of benthic habitats experiences limited annual variation in climatic and oceanographic conditions but seasonal and occasional conditions, particularly coral bleaching and hurricanes, are important influences. The effects of stochastic factors on the country's coral reefs were clearly demonstrated during 1998 when Honduras experienced a major hurricane and bleaching event. Any natural or anthropogenic impacts on reef health will inevitably affect other countries in Latin America, and vice versa, since the marine resources are linked via currents and the functioning of the system transcends political boundaries. Much further work on, for example, movement of larvae and transfer of pollutants is required to delineate the full extent of these links. Anthropogenic impacts, largely driven by the increasing population and proportion of people living in coastal areas, are numerous and include key factors such as agricultural run-off, over-fishing, urban and industrial pollution (particularly sewage) and infrastructure development. Many of these threats act synergistically and, for example, poor watershed management via shifting cultivation, increases sedimentation and pesticide run-off onto coral reefs, which increases stress to corals already affected by decreasing water quality and coral bleaching. Threats from agriculture and fishing are particularly significant because of the size of both industries. The desire to generate urgently required revenue within Honduras has also led to increased tourism which provides an over

  14. Evidence for Dark Energy from the Cosmic Microwave Background Alone Using the Atacama Cosmology Telescope Lensing Measurements

    Science.gov (United States)

    Sherwin, Blake D.; Dunkley, Joanna; Das, Sudeep; Appel, John W.; Bond, J. Richard; Carvalho, C. Sofia; Devlin, Mark J.; Duenner, Rolando; Essinger-Hileman, Thomas; Fowler, Joesph J.; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hincks, Adam D.; Hlozek, Renee; Hughes, John P.; Irwin, Kent D.; Klein, Jeff; Kosowsky, Arthur; Marriage, Tobias A.; Marsden, Danica; Moodley, Kavilan; Menanteau, Felipe; Niemack, Michael D.; Wollack, Ed.

    2011-01-01

    For the first time, measurements of the cosmic microwave background radiation (CMB) alone favor cosmologies with w = -1 dark energy over models without dark energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing deflection power spectrum from the Atacama Cosmology Telescope with temperature and polarization power spectra from the "Wilkinson Microwave Anisotropy Probe. The lensing data break the geometric degeneracy of different cosmological models with similar CMB temperature power spectra. Our CMB-only measurement of the dark energy density Omega(delta) confirms other measurements from supernovae, galaxy clusters and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool.

  15. High performance robotic traverse of desert terrain.

    Energy Technology Data Exchange (ETDEWEB)

    Whittaker, William (Carnegie Mellon University, Pittsburgh, PA)

    2004-09-01

    This report presents tentative innovations to enable unmanned vehicle guidance for a class of off-road traverse at sustained speeds greater than 30 miles per hour. Analyses and field trials suggest that even greater navigation speeds might be achieved. The performance calls for innovation in mapping, perception, planning and inertial-referenced stabilization of components, hosted aboard capable locomotion. The innovations are motivated by the challenge of autonomous ground vehicle traverse of 250 miles of desert terrain in less than 10 hours, averaging 30 miles per hour. GPS coverage is assumed to be available with localized blackouts. Terrain and vegetation are assumed to be akin to that of the Mojave Desert. This terrain is interlaced with networks of unimproved roads and trails, which are a key to achieving the high performance mapping, planning and navigation that is presented here.

  16. Himalayan Mountain Range, Taklimakan Desert, China

    Science.gov (United States)

    1991-01-01

    Looking north from Kashmir India (27.5N, 76.5E) into the Tibetan Plateau and beyond, the Taklimakan Desert of far western China appears to be covered with an extensive layer of haze that blankets the entire region. Reaching even into the western Siberian Plains of the CIS. This rugged land is one of the world's richest treasure troves of mineral wealth but the accessability into this remote area is so difficult that it is not yet economically feasible.

  17. The Palm Desert renewable [hydrogen] transportation system

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlin, C.E.; Lehman, P. [Humboldt State Univ., Arcata, CA (United States). Schatz Energy Research Center

    1998-08-01

    This paper describes the Schatz Energy Research Center (SERC) progress on the Palm Desert Renewable Hydrogen Transportation System Project for the period June 1997 through May 1998. The project began in March 1996. The goal of the Palm Desert Project is to develop a clean and sustainable transportation system for a community. The project demonstrates the practical utility of hydrogen as a transportation fuel and the proton exchange membrane (PEM) fuel cell as a vehicle power system. The project includes designing and building 4 fuel cell powered vehicles, a solar hydrogen generating and refueling station, and a fuel cell vehicle diagnostic center. Over this last year, SERC has built a fuel cell powered neighborhood electric vehicle and delivered it to the City of Palm Desert. The design of the hydrogen refueling station is near completion and it is anticipated that construction will be complete in the fall of 1998. The vehicles are currently being refueled at a temporary refueling station. The diagnostic center is being designed and maintenance procedures as well as computer diagnostic programs for the fuel cell vehicles are being developed. City employees are driving the vehicles daily and monitoring data are being collected. The drivers are pleased with the performance of the vehicles.

  18. Wind modeling of Chihuahuan Desert dust outbreaks

    Science.gov (United States)

    Rivera Rivera, Nancy I.; Gill, Thomas E.; Gebhart, Kristi A.; Hand, Jennifer L.; Bleiweiss, Max P.; Fitzgerald, Rosa M.

    The Chihuahuan Desert region of North America is a significant source of mineral aerosols in the Western Hemisphere, and Chihuahuan Desert dust storms frequently impact the Paso del Norte (El Paso, USA/Ciudad Juarez, Mexico) metropolitan area. A statistical analysis of HYSPLIT back trajectory residence times evaluated airflow into El Paso on all days and on days with synoptic (non-convective) dust events in 2001-2005. The incremental probability—a measure of the areas most likely to have been traversed by air masses arriving at El Paso during dusty days—was only strongly positively associated with the region west-southwest of the city, a zone of known dust source areas. Focused case studies were made of major dust events on 15 April and 15 December 2003. Trajectories approached the surface and MM5 (NCAR/Penn State Mesoscale Model) wind speeds increased at locations consistent with dust sources observed in satellite imagery on those dates. Back trajectory and model analyses suggested that surface cyclones adjacent to the Chihuahuan Desert were associated with the extreme dust events, consistent with previous studies of dust storms in the Southern High Plains to the northeast. The recognition of these meteorological patterns serves as a forecast aid for prediction of dust events likely to impact the Paso del Norte.

  19. CAMEL REARING IN CHOLISTAN DESERT OF PAKISTAN

    Directory of Open Access Journals (Sweden)

    I. ALI, M. SHAFIQ CHAUDHRY1 AND U. FAROOQ

    2009-05-01

    Full Text Available The camel is one of the typical and the best adopted animals of the desert, capable of enduring thirst and hunger for days and is the most patient of land animals. For desert nomads of Pakistani Cholistan, it is a beloved companion, a source of milk and meat, transport facility provider and a racing/dancing animal, thus, playing an important role in the socioeconomic uplift of the local community. Camels of Marrecha or Mahra breed are mainly used for riding and load carrying but may be trained for dancing or racing. Berella is another heavy and milch breed of camel famous for milk production and can produce upto 10-15 liters of milk per day. This breed is also suitable for draught purpose, though comparatively slow due to heavy body. The present paper also describes the traditional camel rearing system used by nomads of Cholistan desert. Some aspects of camel health, production, feeding, socio-economic values, marketing and some constraints and suggestions are also given so that the policy makers may consider them for the welfare of this animal.

  20. Sonoran Desert: Fragile Land of Extremes

    Science.gov (United States)

    Produced and Directed by Wessells, Stephen

    2003-01-01

    'Sonoran Desert: Fragile Land of Extremes' shows how biologists with the U.S. Geological Survey work with other scientists in an effort to better understand native plants and animals such as desert tortoises, saguaro cacti, and Gila monsters. Much of the program was shot in and around Saguaro National Park near Tucson, Arizona. Genetic detective work, using DNA, focuses on understanding the lives of tortoises. Studies of saguaros over many decades clarify how these amazing plants reproduce and thrive in the desert. Threats from fire, diseases in tortoises, and a growing human population motivate the scientists. Their work to identify how these organisms live and survive is a crucial step for the sound management of biological resources on public lands. This 28-minute program, USGS Open-File Report 03-305, was shot entirely in high definition video and produced by the USGS Western Ecological Research Center and Southwest Biological Science Center; produced and directed by Stephen Wessells, Western Region Office of Communications.

  1. Expansion and contraction of Chinese deserts during the Quaternary

    Institute of Scientific and Technical Information of China (English)

    刘东生; 孙继敏

    2002-01-01

    Episodic dune formations during the Quaternary are found in many deserts of China.The causes of desert expansions on different time scales are not the same. Desert extension atabout 1.1 and 0.9 Ma ago were the response to the active tectonic movements, whereas the de-sert evolutions on the ten-thousand years time scale were the response to the orbital scale climaticchanges. Spatial scale studies on desert evolution indicate that desert margins shifted greatly dur-ing the last glacial maximum (LGM) and the Holocene optimum, its changing from 125°E of theLGM to 105°E of the climatic optimum. Historical desertification in the semiarid China is not a re-sponse to climate drought but largely associated with the human impacts (mainly over-cultivation)since about 2300 years ago, which leads to the reworking of the underlying LGM sands.

  2. Aerosol direct radiative forcing in desert and semi-desert regions of northwestern China

    Science.gov (United States)

    Xin, Jinyuan; Gong, Chongshui; Wang, Shigong; Wang, Yuesi

    2016-05-01

    The optical properties of dust aerosols were measured using narrow-band data from a portable sun photometer at four desert and semi-desert stations in northwestern China from 2004 to 2007. Ground-based and satellite observations indicated absorbing dust aerosol loading over the region surrounded by eight large-scale deserts. Radiation forcing was identified by using the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model. The ranges of annual mean aerosol optical depth (AOD), Angström exponents, and single-scattering albedo (SSA) were from 0.25 to 0.35, from - 0.73 to 1.18, and from 0.77 to 0.86, respectively. The ranges of annual mean aerosol direct radiative forcing values at the top of the atmosphere (TOA), mid-atmosphere, and on the surface were from 3.9 to 12.0, from 50.0 to 53.1, and from - 39.1 to - 48.1 W/m2, respectively. The aerosols' optical properties and radiative characteristics showed strong seasonal variations in both the desert and semi-desert regions. Strong winds and relatively low humidity will lead dust aerosols in the atmosphere to an increase, which played greatly affected these optical properties during spring and winter in northwestern China. Based on long-term observations and retrieved data, aerosol direct radiative forcing was confirmed to heat the atmosphere (50-53 W/m2) and cool the surface (- 39 to - 48 W/m2) above the analyzed desert. Radiative forcing in the atmosphere in spring and winter was 18 to 21 W/m2 higher than other two seasons. Based on the dust sources around the sites, the greater the AOD, the more negative the forcing. The annual averaged heating rates for aerosols close to the ground (1 km) were approximately 0.80-0.85 K/day.

  3. Cost estimates for Operation Desert Shield/Desert Storm: a budgetary analysis

    OpenAIRE

    Johnson, J. Andrew.

    1991-01-01

    Operation Desert Shield/Desert Storm (DS/DS) presented unique challenges for estimating the cost of that conflict. This analysis reviews the cost estimates and methodologies developed for that purpose by DoD, CBO and GAO. It considers the budget climate and the role of foreign cash and in-kind contributions. Finally, it reviews the budgeting innovations used to provide and monitor DS/DS defense spending. At the outset of the crisis, costs were estimated to determine the defense funding requir...

  4. The Use of Water During the Crew 144, Mars Desert Research Station, Utah Desert

    Science.gov (United States)

    De Morais Mendonca Teles, Antonio

    2016-07-01

    Well. from November 29th to December 14th, 2014, the author conducted astrobiological and geological surveys, as analog astronaut member of the international Crew 144, at the site of the Mars Society's Mars Desert Research Station, located at a remote location in the Utah desert, United States. The use of water for drinking, bathing, cleaning, etc., in the crew was a major issue for consideration for a human expedition to the planet Mars in the future. The author would like to tell about the factors of the rationalized use of water.

  5. Structural characteristics of an active fold-and-thrust system in the southeastern Atacama Basin, northern Chile

    Science.gov (United States)

    Lin, Yen-Sheng; Chuang, Yi-Rung; Shyu, J. Bruce H.; González, Gabriel; Shen, Chuan-Chou; Lo, Ching-Hua; Liou, Ya-Hsuan

    2016-08-01

    The western South American margin is one of the most active plate boundaries in the world. Using various remote sensing data sets, we mapped the neotectonic characteristics of an area at the southeastern corner of the Atacama Basin, northern Chile, in the Andean forearc. There, one major N-S trending ridge is clearly visible both in the satellite images and in the field. This ridge reaches 250 m above the basin floor in its middle part and is asymmetrical, with a steep eastern slope and a much gentler western slope. The geometry of the ridge indicates that it formed as an asymmetrical anticline. This anticline is likely formed as a shear fault-bend fold, with a major décollement at a depth of about 2.5 km in the Naranja Formation. We suggest that this décollement is a major structure of the Atacama Basin area. From the ages of the ignimbrites and lake deposits that were deformed by this anticline, we obtained a long-term shortening rate of the major underlying structure at about 0.2 mm/yr. This thin-skinned fold-and-thrust system appears to be active since at least about 3 Ma, and could be as long as since middle Miocene. Therefore, crustal structures may play important roles in the Neogene development of the western Andean margin.

  6. Parque Astronómico de Atacama: An Ideal Site for Millimeter, Submillimeter, and Mid-Infrared Astronomy

    Science.gov (United States)

    Bustos, R.; Rubio, M.; Otárola, A.; Nagar, N.

    2014-12-01

    The area of Chajnantor, at more than 5000 m altitude in northern Chile, offers unique atmospheric and operational conditions which arguably make it the best site in the world for millimeter, submillimeter, and mid-infrared observatories. Long-term monitoring of the precipitable water vapor (PWV) column on the Chajnantor plateau has shown its extreme dryness with annual median values of 1.1 mm. Simultaneous measurements of PWV on the Chajnantor plateau (5050 m) and on Cerro Chajnantor (5612 m) show that the latter is around 36% lower under normal atmospheric conditions and up to 80% lower than the plateau in the presence of temperature inversion layers. Recently, the Government of Chile has consolidated the creation of the Parque Astronómico de Atacama (Atacama Astronomical Park), an initiative of the Chilean Commission for Science and Technology (CONICYT). This new park offers an opportunity for national and international projects to settle within its boundaries, gain access to an extremely dry site that is suitable for observations over a broad spectral range, especially in the millimeter to mid-infrared wavelengths, and benefit from operational and logistical support within a secure legal framework.

  7. Parque Astron\\'omico de Atacama: An ideal site for millimeter, sub-millimeter, and mid-infrared astronomy

    CERN Document Server

    Bustos, Ricardo; Otárola, Angel; Nagar, Neil

    2014-01-01

    The area of Chajnantor, at more than 5000 meters altitude in northern Chile, offers unique atmospheric and operational conditions which arguably make it the best site in the world for millimeter, sub-millimeter, and mid-infrared observatories. Long-term monitoring of the precipitable water vapor (PWV) column on the Chajnantor plateau has shown its extreme dryness with annual median values of 1.1 mm. Simultaneous measurements of PWV on the Chajnantor plateau (5050 m) and on Cerro Chajnantor (5612 m) show that the latter is around 36% lower under normal atmospheric conditions and up to 80% lower than the plateau in the presence of temperature inversion layers. Recently, the Government of Chile has consolidated the creation of the Parque Astron\\'omico de Atacama (Atacama Astronomical Park), an initiative of the Chilean Commission for Science and Technology (CONICYT). This new Parque offers an opportunity for national and international projects to settle within its boundaries, gain access to an extremely dry site...

  8. The Atacama Cosmology Telescope: cosmological parameters from three seasons of data

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Jonathan L.; Appel, John William [Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States); Hlozek, Renée A. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Nolta, Michael R.; Battaglia, Nick; Bond, J. Richard [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Acquaviva, Viviana [New York City College of Technology, 300 Jay Street, Brooklyn, NY 11201 (United States); Addison, Graeme E.; Amiri, Mandana; Battistelli, Elia S.; Burger, Bryce [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Ade, Peter A. R. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff, Wales CF24 3AA (United Kingdom); Aguirre, Paula; Barrientos, L. Felipe [Departamento de Astronomía y Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Brown, Ben [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Calabrese, Erminia [Department of Astrophysics, Oxford University, Oxford OX1 3RH (United Kingdom); Chervenak, Jay [Code 553/665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Crichton, Devin [Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Das, Sudeep [High Energy Physics Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont IL 60439 (United States); Devlin, Mark J., E-mail: renee.hlozek@gmail.com [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); and others

    2013-10-01

    We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz and 218 GHz made by the Atacama Cosmology Telescope (ACT) in three seasons of observations from 2008 to 2010. A model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal Sunyaev-Zeldovich (tSZ) effect and the kinematic Sunyaev-Zeldovich (kSZ) effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources, and the correlation between the tSZ effect and infrared sources. The power ℓ{sup 2}C{sub ℓ}/2π of the thermal SZ power spectrum at 148 GHz is measured to be 3.4±1.4  μK{sup 2} at ℓ = 3000, while the corresponding amplitude of the kinematic SZ power spectrum has a 95% confidence level upper limit of 8.6  μK{sup 2}. Combining ACT power spectra with the WMAP 7-year temperature and polarization power spectra, we find excellent consistency with the LCDM model. We constrain the number of effective relativistic degrees of freedom in the early universe to be N{sub eff} = 2.79±0.56, in agreement with the canonical value of N{sub eff} = 3.046 for three massless neutrinos. We constrain the sum of the neutrino masses to be Σm{sub ν} < 0.39 eV at 95% confidence when combining ACT and WMAP 7-year data with BAO and Hubble constant measurements. We constrain the amount of primordial helium to be Y{sub p} = 0.225±0.034, and measure no variation in the fine structure constant α since recombination, with α/α{sub 0} = 1.004±0.005. We also find no evidence for any running of the scalar spectral index, dn{sub s}/dln k = −0.004±0.012.

  9. Paleofluid Flow in the Upper Crust: A Study Case from the Atacama Fault System

    Science.gov (United States)

    Gomila, R.; Arancibia, G.; Cembrano, J. M.; Mitchell, T. M.; Faulkner, D. R.; Jensen Siles, E.

    2014-12-01

    Fault zones and fault-related permeability structures have long been recognized to play a first-order role on fluid flow migration through the crust. However, the nature of the spatial relationship between fault zones and fluid-flow and the evolution of such permeability structures in terms of paleofluid flow quantification is less well understood. This work presents a microfracture analysis aimed to unravel the nature of the fault plumbing system and estimate paleo permeability parameters within the Jorgillo Fault (JF), a subvertical strike-slip fault exposed in the Atacama Fault System in northern Chile. The JF is a ca. 18 km long, NNW striking strike-slip fault with sinistral horizontal separation of ca. 4 km. The JF juxtaposes orthogranulites to the west (JFW) with gabbros to the east side (JFE) wherea 200 m fault-perpendicular transect was mapped and sampled. The fault core consists of ca. 1 m cataclasite bounded by fault gouge zones of ca. 80 cm to the west and 30 cm to the east. A ca. 50 m wide symmetrical damage zone can be observed at field scale. The damage zone in the JFW is characterized by shear fractures and cataclasites whereas the JFE consists of open fractures and veins. The JFW microfracture analysis reveal mm-wide cataclasitic/ultracataclasitic bands orientated subparallel to the JF, calcite veins in a T-fracture orientation, and minor polydirectional chlorite veins. In the JFE, 1-20 mm wide chlorite, quartz-epidote and quartz-calcite veins, can be observed. Chlorite conjugate veins show syntaxial growth textures suggesting dilatational fracturing. Microfractures distribution show shear fractures distributed only in JFW while open fractures are mainly in the JFE. Using models off paleofluid flow, cumulative permeability (i.e. permeability due to all types of microfractures present in the samples) was estimated to range from 2.761x10-11 to 4.89x10-9 m2 on the JFE, and 8.04x10-12 to 4.39x10-8 m2 on the JFW.

  10. Development of self-similar duplex systems. Atacama Fault System, Chile

    Science.gov (United States)

    Jensen, E.; Cembrano, J. M.; Veloso, E. E.

    2009-12-01

    Fault development models are very important to predict geometry and distribution of fractures at all scales. However, models based on structures from microns to km are relatively scarce due to the lack of well-exposed structures. We present structures related to the development of the Bolfín fault in the Atacama Fault System (AFS), covering a scale range of 9 orders of magnitude. The AFS is a 1000 km-long trench-parallel fault system located in the Andean Forearc. The Bolfín fault is a first-order fault of the Caleta Coloso Duplex; it has a trend ~170° and a length >45 km (Fig 1A). It cuts meta-diorites and exhibits a 100-200m wide core of subvertical bands of altered fractured host rock and of foliated cataclasites. Foliation is made of trend-parallel cm-wide shear bands composed of plagioclase fragments (>0,1mm) surrounded by epidote. Around the bands there are many micro fractures oriented within the P-diedra. In the compressive quadrant around a tip point of Bolfín fault, the lower strain faults exhibit an unusual internal structure consisting of fractures arranged in a multi-duplex pattern. This pattern can be seen from metric- (Parulo fault, fig 1C) to mm-scale (Palmera fault fig 1B). Fractures in the pattern can be separated in 2 types: Main Faults: Trend-parallel, longer and with larger offsets. Secondary Fractures: sigmoid-shape fractures distributed in the regions between main faults, all oriented between 15° and 75° with respect to the main faults, meassured in the shear-sense (i.e. in P-diedra). On the basis of the distribution of the 2 types of fractures, the generation sequence can be inferred. The main faults are more widely distributed, and were propagated earlier. The secondary fractures are distributed in smaller areas between larger displacement main faults, and propagated later as linking fractures. The duplex pattern is thus self-similar: faults with multiple-duplex internal structure (Parulo and Palmera fault)are in turn secondary faults

  11. Design and development status of the University of Tokyo Atacama Observatory 6.5m telescope

    Science.gov (United States)

    Morokuma, Tomoki; Aoki, Tsutomu; Doi, Mamoru; Handa, Toshihiro; Kamizuka, Takafumi; Kato, Natsuko; Kawara, Kimiaki; Kohno, Kotaro; Konishi, Masahiro; Koshida, Shintaro; Minezaki, Takeo; Miyata, Takashi; Motohara, Kentaro; Sako, Shigeyuki; Soyano, Takao; Takahashi, Hidenori; Tamura, Yoichi; Tanabe, Toshihiko; Tanaka, Masuo; Tarusawa, Ken'ichi; Yoshii, Yuzuru

    2014-07-01

    We here summarize the design and the current fabrication status for the University of Tokyo Atacama Observatory (TAO) 6.5-m telescope. The TAO telescope is operated at one of the best sites for infrared observations, at the summit of Co. Chajnantor in Chile, and is optimized for infrared observations. The telescope mount, mirrors, and mirror support systems are now at the final design phase. The mechanical and optical designs are done by following and referring to those of the Magellan telescopes, MMT, and Large Binocular Telescope. The final focal ratio is 12.2. The field-of-view is as wide as 25 arcmin in diameter and the plate scale is 2.75 arcsec mm-1. The F/1.25 light-weighted borosilicate (Ohara E6) honeycomb primary mirror is adopted and being fabricated by the Steward Observatory Mirror Laboratory. The primary mirror is supported by 104 loadspreaders bonded to the back surface of the mirror and 6 adjustable hardpoints. The mirror is actively controlled by adjusting the actuator forces based on the realtime wavefront measurement. The actuators are optimized for operation at high altitude of the site, 5640-m above the sea level, by considering the low temperature and low air pressure. The mirror is held in the primary mirror cell which is used as a part of the vacuum chamber when the mirror surface is aluminized without being detached from the cell. The pupil is set at the secondary mirror to minimize infrared radiation into instruments. The telescope has two Nasmyth foci for near-infrared and mid-infrared facility instruments (SWIMS and MIMIZUKU, respectively) and one folded-Caseggrain focus for carry-in instruments. At each focus, autoguider and wavefront measurement systems are attached to achieve seeing-limited image quality. The telescope mount is designed as a tripod-disk type alt-azimuth mount. Both the azimuthal and elevation axes are supported by and run on the hydrostatic bearings. Friction drives are selected for these axis drives. The telescope

  12. Nearshore currents along the Karnataka coast, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Dora, G.U.; Philip, C.S.; Pednekar, P.S.; Singh, J.

    Measured current data at 7 locations and tide data at 3 locations during the pre-summer monsoon period along the west coast of India is used in the study. The surface currents during March showed a predominant northward trend and during April...

  13. QUANTIFYING CARBON SEQUESTRATION IN A PROSOPIS CINERARIA - DOMINATED DESERT OF THE UAE

    Energy Technology Data Exchange (ETDEWEB)

    Taoufik Ksiksi; Owaisha Binhajraf [Biology Department - College of Science - UAE University, Al-Ain (United Arab Emirates)

    2008-09-30

    Prosopis cinerea is the largest desert tree of the region and constitutes a key species for the United Arab Emirates (UAE) rangelands. It promotes biodiversity and improves soil characteristics. The tree's effect on the soil surrounding its trunk constitutes an important aspect of the ecology of these desert ecosystems and good forage source for many wildlife and livestock species in the region. The present study will, therefore, shed some light on the effect of P. cineraria on soil carbon sequestration. The study area was located in the Emirate of Sharjah on the eastern coast of the UAE. A total of 15 stands, representing 3 different tree sizes (ie. small less than 2 m; medium around 5 m; and large more than 5 m) were identified. 4 sandy soil samples were collected around each tree. Two samples were collected directly from under the tree and the other two samples were collected from the area beyond the canopy cover. Percent soil carbon varied between the various tree sizes and was also affected by the position under P. cineraria canopy. Large P. cineraria individuals had the highest percentage of soil carbon (6.46 percent) when compared to the other 2 tree sizes. Suggesting that large and medium P. cineraria trees are contributing to the overall input of soil carbon and therefore improving soil carbon sequestration. More substantial efforts are to be implemented in the UAE to increase P. cineraria plantations, as they constitute a crucial component of the health of desert ecosystems. The urgency of the actions stems from the need for long periods, up to 30 years, for the P. cineraria trees to reach a crown diameter of at least 5 meters.

  14. Diversity, abundance and conservation of birds in an agroecosystem in the Ica desert, Peru

    Directory of Open Access Journals (Sweden)

    Letty Salinas

    2013-05-01

    Full Text Available Present work investigates the impact of the agricultural activity in the Peruvian coast on the biodiversity of birds. The study includes the monitoring of birds in asparagus and grapes farms of Ica valley, from January-2004 to January-2006. We evaluated eight types of habitats distributed in a total of 1288 has. Throughout the period of study we registered 93 species of birds. The abundance, richness and diversity were greater in the summers. The greater abundance happened in the habitats of land of asparagus, river brushwood and live fences. The greater richness and diversity happened in January-2006 in alfalfa cultures with huarangos and live fences. The most abundant species were the residents, as Zenaida meloda (6,6 ind./it has, Pygochelidon cyanoleuca (5,9 and the migratory Hirundo rustica (5,9. We registered 12 migratory species. From the conservationist point of view, the number of species catalogued in some degree of threat, at national and international level, is very high. We can emphasize the vulnerable Xenospingus concolor, the Peruvian endemic Colaptes atricollis and the species of desert Geositta peruviana, Sporophila simplex and Burhinus superciliaris. This study demonstrates the importance of agroecosystems in the conservation of the Peruvian Coastal Desert biodiversity, in particular if the enterprise carries out a policy of respect to environment.

  15. The Coast Alarm System Editor

    International Nuclear Information System (INIS)

    The OECD Halden Reactor Project has for several years worked in the field of alarm handling. COAST was developed based on long experience with several different methods for identification of plant status and detection of plant anomalies. COAST has been delivered to a number of different organisations which generate their own applications. With COAST one can implement many alarm generation or structuring methods. So far, the alarm system is defined using a COAST language, COLA. Now, a first version of an editor to implement alarm systems is available, to support alarm system designers to write and structure their COLA code. It is developed based on general guidelines for user interface design and a thorough discussion of different editor types. The most important functionality needed when designing alarm systems for complex processes was emphasized when choosing the type of editor. A structure-oriented editor is currently implemented, and the report gives a description for how to include graphic features towards a more complete editor in the future. Support and encouragement for reuse of code is obtained by defining classes in a class library browser. Separate applications with their specific object definitions are constructed in an application browser. In this way the alarm classes from the class libraries can easily be used in several applications. The application browser offers the possibility to organize the alarm objects in a structured hierarchy. In big complex alarm systems such a structuring feature is of vital importance to keep the overview of the alarm system and to perform maintenance. (author)

  16. Ivory Coast: Country Status Report.

    Science.gov (United States)

    Bruhn, Thea C.

    A survey of the status of language usage in the Ivory Coast begins with an overview of the usage patterns of French, the official language, and the five most commonly used native languages: Jula, Anyi-Baoule, Senoufo, Bete, and Dan. Recent Ivorian efforts at language planning, development, and research are also highlighted. A matrix follows that…

  17. French in the Ivory Coast.

    Science.gov (United States)

    Djite, Paulin G.

    1989-01-01

    Overviews the Ivory Coast's sociolinguistic situation. Standard French, restricted to the elite, is threatened by the local lingua franca. The spread and functional allocations of Dyula and Popular French support the point that the pervasive use of a language does not always lead to its adoption as a national language. (CB)

  18. The Palm Desert Renewable Hydrogen Transportation System

    Energy Technology Data Exchange (ETDEWEB)

    Lehman, P. [Humboldt State Univ., Arcata, CA (United States)

    1996-10-01

    The present paper describes, for purposes of the Department of Energy (DoE) Hydrogen Program Review, Schatz Energy Research Center (SERC) progress on the Palm Desert Renewable Hydrogen Transportation System Project for the period January through June 1996. This period represents the first six months of the three year project. The estimated cost over three years is $3.9M, $1.859M of which is funded by the DoE ($600 k for fiscal year 1996). The goal of the Palm Desert Project is to develop a clean and sustainable transportation system for a community. The project will demonstrate the practical utility of hydrogen as a transportation fuel and proton exchange membrane (PEM) fuel cells as vehicle power plants. This transportation system will be developed in the City of Palm Desert in southern California and will include a fleet of 8 fuel cell powered vehicles, solar and wind powered hydrogen generating facilities, a consumer-ready refueling station, and a service infrastructure. The system holds the promise of a clean environment and an energy supply that is predictable, domestic, safe, and abundant. During, the first part of 1996 SERC has nearly completed building a fuel cell powered personal utility vehicle, which features an upgraded safety and computer system; they have designed and built a test bench that is able to mimic golf cart loads and test fuel cell system auxiliary components; they have begun the design of the solar hydrogen generating station; they have worked with Sandia National Laboratory on an advanced metal hydride storage system; they have increased the power density of the SERC fuel cell by as much as 50%; and they have reached out to the rest of the world with a new fact sheet, world wide web pages, a press release, video footage for a television program. and instruction within the community.

  19. Distance sampling for Sonoran Desert tortoises

    Science.gov (United States)

    Swann, D.E.; Averill-Murray, R. C.; Schwalbe, C.R.

    2002-01-01

    We used line transects and distance sampling in combination with radiotelemetry to estimate density of a desert tortoise (Gopherus agassizii) population in the Rincon Mountains near Tucson, Arizona, USA, as part of a long-term study evaluating the impact of urban development on tortoises. During 2000, 34 1-km transects were each sampled twice in the 368.5-ha study area. We observed 46 tortoises with midline carapace lengths ???150 mm (subadults and adults) plus 7 juveniles on transects. For subadults and adults, the encounter rate was 0.63 tortoises/km, and the mean proportion of tortoises observable during radiotelemetry, conducted concurrently with transect sampling, was 82%. Corrected mean density based on line transects and radiotelemetry was 0.523 tortoises/ha (CV = 22.99, 95% CI = 0.29-0.79), and absolute abundance in the study area was estimated to be 193 (CV = 23.0%, CI = 107-291). Using the 2 independent coverages of transects as separate samples, the Lincoln-Petersen mark-recapture estimator produced an abundance estimate of 224 subadult and adult tortoises (CV = 53.9%, CI = 72-440). Transects measured on the ground over uneven topography resulted in 3% smaller estimates of density when compared to analysis with transect lengths determined from coordinates plotted on a map. Distance sampling appears to be a feasible method of estimating density of Sonoran Desert populations of the desert tortoise, but transect lengths should be based on mapped rather than measured distances to prevent biases caused by uneven topography.

  20. Physiological conjunction of allelochemicals and desert plants.

    Directory of Open Access Journals (Sweden)

    Avital Yosef Friedjung

    Full Text Available Plants exchange signals with other physical and biological entities in their habitat, a form of communication termed allelopathy. The underlying principles of allelopathy and secondary-metabolite production are still poorly understood, especially in desert plants. The coordination and role of secondary metabolites were examined as a cause of allelopathy in plants thriving under arid and semiarid soil conditions. Desert plant species, Origanum dayi, Artemisia sieberi and Artemisia judaica from two different sources (cultivar cuttings and wild seeds were studied in their natural habitats. Growth rate, relative water content, osmotic potential, photochemical efficiency, volatile composition and vital factors of allelopathy were analyzed at regular intervals along four seasons with winter showing optimum soil water content and summer showing water deficit conditions. A comprehensive analysis of the volatile composition of the leaves, ambient air and soil in the biological niche of the plants under study was carried out to determine the effects of soil water conditions and sample plants on the surrounding flora. Significant morpho-physiological changes were observed across the seasons and along different soil water content. Metabolic analysis showed that water deficit was the key for driving selective metabolomic shifts. A. judaica showed the least metabolic shifts, while A. sieberi showed the highest shifts. All the species exhibited high allelopathic effects; A. judaica displayed relatively higher growth-inhibition effects, while O. dayi showed comparatively higher germination-inhibition effects in germination assays. The current study may help in understanding plant behavior, mechanisms underlying secondary-metabolite production in water deficit conditions and metabolite-physiological interrelationship with allelopathy in desert plants, and can help cull economic benefits from the produced volatiles.

  1. Elevation Derivatives for Mojave Desert Tortoise Habitat

    Science.gov (United States)

    Wallace, Cynthia S.A.; Gass, Leila

    2008-01-01

    This report describes the methods used to derive various elevation-derivative grids that were inputted to the Mojave Desert Tortoise Habitat model (L. Gass and others, unpub. data). These grids, which capture information on surface roughness and topographic characteristics, are a subset of the environmental datasets evaluated for the tortoise habitat model. This habitat model is of major importance to the U.S. Fish and Wildlife Service, which is charged with management of this threatened population, including relocating displaced tortoises to areas identified as suitable habitat.

  2. From desert to deluge in the Mediterranean

    OpenAIRE

    McKenzie, Judith A.

    2002-01-01

    Some time between five and six million years ago, the Mediterranean Sea became isolated from the Atlantic Ocean. In consequence some areas dried out -- hence the title of Kenneth Hsü’s book The Mediterranean was a Desert 1 -- and large salty lakes recharged by rivers flowing through deep canyons replaced the previously marine basins. During this time, the remaining bodies of water were either too salty or not salty enough for normal marine fauna to flourish. This was the so-called Messinian s...

  3. Background aerosol composition in the Namib desert

    International Nuclear Information System (INIS)

    The sulfur content of atmospheric particulate matter in non-urban areas is apparently rising above natural levels in the Northern Hemisphere. Sulfur emissions to the atmosphere are also increasing with increasing combustion of fossil fuels. Current research is being focussed not only on gaseous sulfur dioxide, but also on particulate forms, including sulfates and sulfuric acid. A global network of non urban studies using proton induced X-ray emission (PIXE) of which the sampling site at Gobabeb in the Namib desert is one, are developing a data base on which questions of natural levels of sulfur can be answered

  4. Desert tortoise use of burned habitat in the Eastern Mojave desert

    Science.gov (United States)

    Drake, Karla K.; Esque, Todd C.; Nussear, Kenneth E.; DeFalco, Lesley; Scoles, Sara; Modlin, Andrew T.; Medica, Philip A.

    2015-01-01

    Wildfires burned 24,254 ha of critical habitat designated for the recovery of the threatened Mojave desert tortoise (Gopherus agassizii) in southern Nevada during 2005. The proliferation of non-native annual grasses has increased wildfire frequency and extent in recent decades and continues to accelerate the conversion of tortoise habitat across the Mojave Desert. Immediate changes to vegetation are expected to reduce quality of critical habitat, yet whether tortoises will use burned and recovering habitat differently from intact unburned habitat is unknown. We compared movement patterns, home-range size, behavior, microhabitat use, reproduction, and survival for adult desert tortoises located in, and adjacent to, burned habitat to understand how tortoises respond to recovering burned habitat. Approximately 45% of home ranges in the post-fire environment contained burned habitat, and numerous observations (n = 12,223) corroborated tortoise use of both habitat types (52% unburned, 48% burned). Tortoises moved progressively deeper into burned habitat during the first 5 years following the fire, frequently foraging in burned habitats that had abundant annual plants, and returning to adjacent unburned habitat for cover provided by intact perennial vegetation. However, by years 6 and 7, the live cover of the short-lived herbaceous perennial desert globemallow (Sphaeralcea ambigua) that typically re-colonizes burned areas declined, resulting in a contraction of tortoise movements from the burned areas. Health and egg production were similar between burned and unburned areas indicating that tortoises were able to acquire necessary resources using both areas. This study documents that adult Mojave desert tortoises continue to use habitat burned once by wildfire. Thus, continued management of this burned habitat may contribute toward the recovery of the species in the face of many sources of habitat loss.

  5. Resilience Mechanisms and Recovery in a Chihuahuan Desert Rangeland Ecosystem

    Science.gov (United States)

    Background: Desert grassland ecosystems of the Chihuahuan Desert, and other parts of the southwestern U.S., underwent significant changes from the late 1800s through the 1950s. Most often, grassland states were converted to shrubland states. Such transitions have been associated with diminished live...

  6. Negev: Land, Water, and Life in a Desert Environment

    Science.gov (United States)

    Back, William

    In view of the continuing increased concern about the extreme fragility of deserts and desert margins, Negev provides a timely discussion of land-use practices compatible with the often conflicting goals of preservation and development. The success o f agricultural and hydrologic experiments in the Negev desert of Israel offers hope to the large percentage of the world's population that lives with an unacceptably low quality of life in desert margins. Deserts are the one remaining type of open space that, with proper use, has the potential for alleviating the misery often associated with expanding population.In addition to the science in the book, the author repeatedly reinforces the concept that “western civilization is inextricably bound to the Negev and its environs, from which it has drawn, via its desert-born religions—Judasium, Christianity, and Islam—many of the mores and concepts, and much of the imagery and love of the desert, including man's relation to nature and to ‘God’.” Deserts often are erroneously perceived to be areas of no water: In reality, these are areas in which a little rainfall occurs sporadically and unpredictably over time. This meager water supply can be meticulously garnered to produce nutritious crops and forage.

  7. Food Deserts and Overweight Schoolchildren: Evidence from Pennsylvania

    Science.gov (United States)

    Schafft, Kai A.; Jensen, Eric B.; Hinrichs, C. Clare

    2009-01-01

    The concept of the "food desert", an area with limited access to retail food stores, has increasingly been used within social scientific and public health research to explore the dimensions of spatial inequality and community well-being. While research has demonstrated that food deserts are frequently characterized by higher levels of poverty and…

  8. 76 FR 66354 - DesertXpress Enterprises, LLC and DesertXpress HSR Corporation-Construction and Operation...

    Science.gov (United States)

    2011-10-26

    ... Surface Transportation Board DesertXpress Enterprises, LLC and DesertXpress HSR Corporation-- Construction..., DOT. ACTION: Notice of construction and operation exemption. SUMMARY: The Board grants an exemption... to environmental mitigation conditions and the condition that DXE build the route designated...

  9. Landscape Sustainability in a Sonoran Desert City

    Directory of Open Access Journals (Sweden)

    Chris A. Martin

    2008-01-01

    Full Text Available The objective of this paper is to discuss concepts of landscape sustainability in the Phoenix metropolitan area. Phoenix is situated in the greater Salt River Valley of the lower Sonoran Desert in the southwest United States. In this paper I use the ecological frameworks of ecosystem services and resiliency as a metric for understanding landscape sustainability. An assessment of landscape sustainability performance benchmarks were made by surveying research findings of scientists affiliated with the Central Arizona Phoenix Long Term Ecological Research Project (CAP LTER. In Phoenix, present day emphases on cultural, aesthetic, and habitat formation ecosystem services within an arid ecoregion of low natural resilience coupled to a complex matrix of socioeconomic stratification, excessive landscape water use and pruning practices has had the undesired effect of degrading landscape sustainability. This has been measured as mixed patterns of plant diversity and human-altered patterns of carbon regulation, microclimate control, and trophic dynamics. In the future, sustainable residential landscaping in desert cities such as Phoenix may be fostered through use of water-conserving irrigation technologies, oasis-style landscape design motifs, recycling of landscape green waste, and conservative plant pruning strategies.

  10. Vertebrate fossils and trace fossils in Upper Jurassic-Lower cretaceous red beds in the Atacama region, Chile

    Science.gov (United States)

    Bell, C. M.; Suárez, M.

    Pterosaur, dinosaur, and crocodile bones are recorded here for the first time in Upper Jurassic-Lower Cretaceous red beds in the Atacama region east of Copiapó, Chile. Trace fossils produced by vertebrate animals include the footprints of theropod dinosaurs and the depressions of sandstone laminae interpreted as burrows and foot impressions. The fossils occur in the 1500-meter-thick Quebrada Monardes Formation, which consists predominantly of the aeolian and alluvial deposits of a semi-arid terrestrial environment. Vertebrate fossils are very rare in Chile. Dinosaur bones and footprints have previously been recorded at only seven locations, and pterosaur remains at only one location. The newly discovered dinosaur bones are the oldest to be described in Chile.

  11. The Atacama Cosmology Telescope: Detection or Sunyaev-Zel'Dovich Decrement in Groups and Clusters Associated with Luminous Red Galaxies

    Science.gov (United States)

    Hand, Nick; Appel, John William; Battaglia, Nick; Bond, J. Richard; Das, Sudeep; Devlin, Mark J.; Dunkley, Joanna; Dunner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W.; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D.; Hlozek, Renee; Hughes, John P.; Irwin, Kent D.; Klein, Jeff; Kosowsky, Arthur; Lin, Yen-Ting; Marriage, Tobias A.; Marsden, Danica; McLaren, Mike; Wollack, Ed

    2010-01-01

    We present a detection of the Sunyaev-Zel'dovich (SZ) decrement associated with the Luminous Red Galaxy (LRG) sample of the Sloan Digital Sky Survey. The SZ data come from 148 GHz maps of the equatorial region made by the Atacama Cosmology Telescope (ACT). The LRG sample is divided by luminosity into four bins, and estimates for the central Sunyaev-Zel'dovich temperature decrement are calculated through a stacking process. We detect and account for a bias of the SZ signal due to weak radio sources. We use numerical simulations to relate the observed decrement to Y(sub 200) and clustering properties to relate the galaxy luminosity bins to mass. We also use a relation between BCG luminosity and cluster mass based on stacked gravitational lensing measurements to estimate the characteristic halo masses. The masses are found to be in the range approx.10(exp 13) - 10(exp 14)/h Stellar Mass, a lower range than has been previously probed.

  12. Solar science with the Atacama Large Millimeter/submillimeter Array - A revolutionizing new view of our Sun

    CERN Document Server

    Wedemeyer, S; Brajsa, R; Barta, M; Hudson, H; Fleishman, G; Loukitcheva, M; Fleck, B; Kontar, E P; De Pontieu, B; Tiwari, S K; Kato, Y; Soler, R; Yagoubov, P; Black, J H; Antolin, P; Scullion, E; Gun'ar, S; Labrosse, N; Benz, A O; Ludwig, H -G; Hauschildt, P; Doyle, J G; Nakariakov, V M; Solanki, S K; White, S M; Ayres, T; Heinzel, P; Karlicky, M; Van Doorsselaere, T; Gary, D; Alissandrakis, C E; Nindos, A; van der Voort, L Rouppe; Shimojo, M; Zaqarashvili, T; Perez, E

    2015-01-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) is a new powerful tool for observing the Sun at high spatial, temporal, and spectral resolution. These capabilities can address a broad range of fundamental scientific questions in solar physics. The radiation observed by ALMA originates mostly from the chromosphere - a complex and dynamic region between the photosphere and corona, which plays a crucial role in the transport of energy and matter and, ultimately, the heating of the outer layers of the solar atmosphere. Based on first solar test observations, strategies for regular solar campaigns are currently being developed. State-of-the-art numerical simulations of the solar atmosphere and modeling of instrumental effects can help constrain and optimize future observing modes for ALMA. Here we present a short technical description of ALMA and an overview of past efforts and future possibilities for solar observations at submillimeter and millimeter wavelengths. In addition, selected numerical simulatio...

  13. Red Tide off Texas Coast

    Science.gov (United States)

    2002-01-01

    Red tides (algae) bloomed late this summer along a 300-mile stretch of Texas' Gulf Coast, killing millions of fish and shellfish as well as making some people sick. State officials are calling this the worst red tide bloom in 14 years. The algae produces a poison that paralyzes fish and prevents them from breathing. There is concern that the deadly algae could impact or even wipe out this year's oyster harvest in Texas, which usually peaks during the Thanksgiving and Christmas holidays. The red tides were first observed off the Texas coast in mid-August and have been growing steadily in size ever since. Red tides tend to bloom and subside rapidly, depending upon changes in wind speed and direction, water temperature, salinity, and rainfall patterns (as the algae doesn't do as well in fresher water). This true-color image of the Texas Gulf Coast was acquired on September 29, 2000, by the Moderate-resolution Imaging Spectroradiometer (MODIS) flying aboard NASA's Terra spacecraft. The red tide can be seen as the dark reddish discoloration in the ocean running southwest to northeast along the coast. In this scene, the bloom appears to be concentrated north and east of Corpus Christi, just off Matagorda Island. The image was made at 500-meter resolution using a combination of MODIS' visible bands 1 (red), 4 (green), and 3 (blue). The city of Houston can be seen clearly as the large, greyish cluster of pixels to the north and west of Galveston Bay, which is about mid-way up the coastline in this image. Also visible in this image are plumes of smoke, perhaps wildfires, both to the north and northeast of Houston. For more information about red tides, refer to the Texas Red Tide Web site. Image courtesy Andrey Savtchenko, MODIS Data Support Team, and the MODIS Ocean Team, NASA's Goddard Space Flight Center

  14. Evolution and Functional Classification of Vertebrate Gene Deserts

    Energy Technology Data Exchange (ETDEWEB)

    Ovcharenko, I; Loots, G; Nobrega, M; Hardison, R; Miller, W; Stubbs, L

    2004-07-14

    Gene deserts, long stretches of DNA sequence devoid of protein coding genes, span approximately one quarter of the human genome. Through human-chicken genome comparisons we were able to characterized one third of human gene deserts as evolutionarily stable - they are highly conserved in vertebrates, resist chromosomal rearrangements, and contain multiple conserved non-coding elements physically linked to their neighboring genes. A linear relationship was observed between human and chicken orthologous stable gene deserts, where the human deserts appear to have expanded homogeneously by a uniform accumulation of repetitive elements. Stable gene deserts are associated with key vertebrate genes that construct the framework of vertebrate development; many of which encode transcription factors. We show that the regulatory machinery governing genes associated with stable gene deserts operates differently from other regions in the human genome and relies heavily on distant regulatory elements. The regulation guided by these elements is independent of the distance between the gene and its distant regulatory element, or the distance between two distant regulatory cassettes. The location of gene deserts and their associated genes in the genome is independent of chromosomal length or content presenting these regions as well-bounded regions evolving separately from the rest of the genome.

  15. Desert Research and Technology Studies 2005 Report

    Science.gov (United States)

    Ross, Amy J.; Kosmo, Joseph J.; Janoiko, Barbara A.; Bernard, Craig; Splawn, Keith; Eppler, Dean B.

    2006-01-01

    During the first two weeks of September 2005, the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) Advanced Extravehicular Activity (AEVA) team led the field test portion of the 2005 Research and Technology Studies (RATS). The Desert RATS field test activity is the culmination of the various individual science and advanced engineering discipline areas year-long technology and operations development efforts into a coordinated field test demonstration under representative (analog) planetary surface terrain conditions. The purpose of the RATS is to drive out preliminary exploration concept of operations EVA system requirements by providing hands-on experience with simulated planetary surface exploration extravehicular activity (EVA) hardware and procedures. The RATS activities also are of significant importance in helping to develop the necessary levels of technical skills and experience for the next generation of engineers, scientists, technicians, and astronauts who will be responsible for realizing the goals of the Constellation Program. The 2005 Desert RATS was the eighth RATS field test and was the most systems-oriented, integrated field test to date with participants from NASA field centers, the United States Geologic Survey (USGS), industry partners, and research institutes. Each week of the test, the 2005 RATS addressed specific sets of objectives. The first week focused on the performance of surface science astro-biological sampling operations, including planetary protection considerations and procedures. The second week supported evaluation of the Science, Crew, Operations, and Utility Testbed (SCOUT) proto-type rover and its sub-systems. Throughout the duration of the field test, the Communications, Avionics, and Infomatics pack (CAI-pack) was tested. This year the CAI-pack served to provide information on surface navigation, science sample collection procedures, and EVA timeline awareness. Additionally, 2005 was the first

  16. Properties of Desert Sand and CMAS Glass

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2014-01-01

    As-received desert sand from a Middle East country has been characterized for its phase composition and thermal stability. X-ray diffraction analysis showed the presence of quartz (SiO2), calcite (CaCO3), gypsum (CaSO4.2H2O), and NaAlSi3O8 phases in as-received desert sand and showed weight loss of approx. 35 percent due to decomposition of CaCO3 and CaSO4.2H2O when heated to 1400 C. A batch of as-received desert sand was melted into calcium magnesium aluminosilicate (CMAS) glass at approx. 1500 C. From inductively coupled plasma-atomic emission spectrometry, chemical composition of the CMAS glass was analyzed to be 27.8CaO-4MgO-5Al2O3-61.6SiO2-0.6Fe2O3-1K2O (mole percent). Various physical, thermal and mechanical properties of the glass have been evaluated. Bulk density of CMAS glass was 2.69 g/cc, Young's modulus 92 GPa, Shear modulus 36 GPa, Poisson's ratio 0.28, dilatometric glass transition temperature (T (sub g)) 706 C, softening point (T (sub d)) 764 C, Vickers microhardness 6.3 +/- 0.4 GPa, indentation fracture toughness 0.75 +/- 0.15 MPa.m (sup 1/2), and coefficient of thermal expansion (CTE) 9.8 x 10 (exp -6)/degC in the temperature range 25 to 700 C. Temperature dependence of viscosity has also been estimated from various reference points of the CMAS glass using the Vogel-Fulcher-Tamman (VFT) equation. The glass remained amorphous after heat treating at 850 C for 10 hr but crystallized into CaSiO3 and Ca-Mg-Al silicate phases at 900 C or higher temperatures. Crystallization kinetics of the CMAS glass has also been investigated by differential thermal analysis (DTA). Activation energies for the crystallization of two different phases in the glass were calculated to be 403 and 483 kJ/mol, respectively.

  17. Geomorphometirc Segmentation of Shield Deserts by Self-Organizing Maps

    Science.gov (United States)

    Foroutan, M.; Kompanizare, M.; Ehsani, A. H.

    2015-12-01

    Shield deserts have developed on ancient crystalline bedrocks and mainly composed of folded and faulted rocks hardened by heat and pressure over millions of years. They were unearthed by erosion and form steep-sided hills and basins filled with sediments. The Sahara, Arabian, southern African, central Kavir and Australian deserts are in this group. Their ranges usually supply groundwater resources or in some regions contain huge oil reservoirs. Geomorphological segmentation of shield deserts is one of the fundamental tools in their land use or site investigation planning as well as in their surface water and groundwater management. In many studies the morphology of shield deserts has been investigated by limited qualitative and subjective methods using limited number of simple parameters such as surface elevation and slope. However the importance of these regions supports the need for their accurate and quantitative morphologic classification. The present study attempts to implement a quantitative method, Self-Organizing Map (SOM), for geomorphological classification of a typical shield desert within Kavir Desert, Iran. The area is tectonically stable and characterized by flat clay pans, playas, well-developed pediments around scattered and low elevation ranges. Twenty-two multi-scale morphometric parameters were derived from the first- to third-orders partial derivatives of the surface elevation. Seven optimized parameters with their proper scales were selected by Artificial Neural Networks, Optimum Index Factor, Davies-Bouldin Index and statistic models. Finally, the area was segmented to seven homogeneous areas by SOM algorithm. The results revealed the most distinguishing parameter set (MDPS) for morphologic segmentation of shield deserts. The same segmentation results through using MDPS for another shield deserts in Australia proves the applicability of MDPS for shield deserts segmentation.

  18. How to identify food deserts in Amazonian cities?

    OpenAIRE

    Davies, Gemma; Frausin Bustamante, Gina Giovanna; Parry, Luke Thomas Wyn

    2016-01-01

    Food deserts are areas without affordable access to healthy foods. This paper explores whether food deserts are present within urban areas of the Brazilian Amazon. The availability and price of a variety of food products was surveyed in a total of 304 shops, across 3 cities in 2015. Least-cost distances were calculated to estimate travel distance to access products, with map overlay used to help identify areas with poor access to a variety of healthy food - these were defined as food deserts.

  19. Aesthetic value of aeolian geomorphosites in the Kumtagh Desert, China

    Institute of Scientific and Technical Information of China (English)

    JinFeng Wu; Xin Wang; Feng Guo; Lei Li

    2014-01-01

    Tourism development of aeolian geomorphosites in the Kumtagh Desert is beneficial to both harmonious development of human-nature relationship and the sustainable development of the tourist industry in the Kumtagh Desert and its sur-rounding area. This paper adopts some research methods including field observation, expert assessment, and systematic investigation to analyze and evaluate the aesthetic value of aeolian geomorphosites in the Kumtagh Desert from three aspects of"Beauty of Morphology","Beauty of Color"and"Beauty of Forms". This research is a creative work in the field of aeolian geomorphosites combining the method of aeolian geomorphology and tourism geography.

  20. Thermodynamic and pedogenic differences between desert microsites

    Science.gov (United States)

    Young, Michael; Caldwell, Todd; Lin, Henry

    2014-05-01

    Feedbacks exist between soil properties, climate and ecological productivity. In arid alluvial fan deposits common to the southwestern United States, the strength of these complex feedbacks change slowly over long time frames (e.g., 10s to 100s of millennia) as the climate has become drier and warmer. The feedbacks are also influenced by relatively short-time-frame processes of shrub establishment and subshrub processes that create distinct interspace and sub-canopy microsites. Pedogenic processes in both cases proceed at different rates—slowly in interspaces and rapidly beneath canopies—yet both are subject to similar energy and mass inputs entering the system from above the canopy. In this study, we apply a branch of non-equilibrium (open system) thermodynamics to explain desert pedogenic processes and how the two microsites are tied together. The general concept is that energy and mass flow naturally in directions that minimize gradients, hence maximizing randomness and entropy. We hypothesize that younger soils begin as random bodies, but that energy input from the sun, and mass input from water, dust and vegetation create gradients over time, leading to microsites of pavements and canopies. These features eventually reach metastability and the potential for self-destruction increases (i.e., desert pavements eventually fall apart and erode). We seek to apply these concepts to Mojave Desert soils/ecosystems that have been studied in the field and the laboratory, with the goal of explaining and/or predicting the pathways of pedogenesis in these environments. Of particular interest is how these concepts might be applied in microsite locations influence the two-way coupling of pedologic development and ecosystem functions, and whether we can predict the strength of these feedbacks and processes using knowledge of soil systems today. The field site is found in the Mojave Natural Preserve, CA, USA, where high spatial resolution infiltrometer measurements were

  1. Holocene climatic change in Hunshandake Desert

    Institute of Scientific and Technical Information of China (English)

    JIN Heling; SU Zhizhu; SUN Liangying; SUN Zhong; ZHANG Hong; JIN Liya

    2004-01-01

    Research on the geological data of Hunshandake Desert in China monsoon region revealed that Holocene summer monsoon had experienced six prevailing periods and seven weakening periods. The climatic humidity and the vegetation had also undergone the similar periodical variation influenced by the monsoon periodicity. The period when summer monsoon prevailed or winter monsoon weakened and climatic humidity and vegetation coverage relatively increased, corresponded to the global warming events;whereas the period when summer monsoon weakened or winter monsoon prevailed and climatic humidity and vegetation coverage relatively decreased, corresponded to the arid events in middle to low latitudes and the cold events in North Atlantic. As for the changing regularity of summer monsoon intensity there were two distinct periodicities of 1456 years and 494 years, also these two periodicities had global significance.

  2. GPUs: An Oasis in the Supercomputing Desert

    CERN Document Server

    Kamleh, Waseem

    2012-01-01

    A novel metric is introduced to compare the supercomputing resources available to academic researchers on a national basis. Data from the supercomputing Top 500 and the top 500 universities in the Academic Ranking of World Universities (ARWU) are combined to form the proposed "500/500" score for a given country. Australia scores poorly in the 500/500 metric when compared with other countries with a similar ARWU ranking, an indication that HPC-based researchers in Australia are at a relative disadvantage with respect to their overseas competitors. For HPC problems where single precision is sufficient, commodity GPUs provide a cost-effective means of quenching the computational thirst of otherwise parched Lattice practitioners traversing the Australian supercomputing desert. We explore some of the more difficult terrain in single precision territory, finding that BiCGStab is unreliable in single precision at large lattice sizes. We test the CGNE and CGNR forms of the conjugate gradient method on the normal equa...

  3. Desert ants learn vibration and magnetic landmarks.

    Directory of Open Access Journals (Sweden)

    Cornelia Buehlmann

    Full Text Available The desert ants Cataglyphis navigate not only by path integration but also by using visual and olfactory landmarks to pinpoint the nest entrance. Here we show that Cataglyphis noda can additionally use magnetic and vibrational landmarks as nest-defining cues. The magnetic field may typically provide directional rather than positional information, and vibrational signals so far have been shown to be involved in social behavior. Thus it remains questionable if magnetic and vibration landmarks are usually provided by the ants' habitat as nest-defining cues. However, our results point to the flexibility of the ants' navigational system, which even makes use of cues that are probably most often sensed in a different context.

  4. Petroleum related hazards relating to Desert Storm

    International Nuclear Information System (INIS)

    In this paper the findings and recommendations of a workshop convened to discuss the toxicity of crude oil and associated chemicals as related to military operations during Operation Desert Storm are presented. Since concern was limited to military operations, only acute toxicity, combustion hazard and explosive hazard were considered. These recommendations were developed to assist operational and medical personnel serving in the Middle East, but have some relevancy to operations that continue during the process of mitigating the damage done to that region. The issues arising from the large amount of oil fire smoke currently being produced by burning Kuwaiti wells were not addressed by the workshop. However, workshop findings indicate a need to study the composition, distribution and health consequences of oil smoke exposure

  5. Qingdao - Pearl onthe Shandong coast

    Institute of Scientific and Technical Information of China (English)

    BRUCE CONNOLLY

    2004-01-01

    <正> Qingdao, its name is synonymous with beer. Tsingtao Beer, one of the country’s finest, has put the city firmly onto the international scene. However, there is so much more to this pearl on the coast of Shandong Province. As China goes forward to the 2008 Olympics the city will become even better known for it has been chosen as the venue for the ocean sailing events.Qingdao occupies a peninsula jutting into the Yellow Sea. It is hilly, with a coastline of rocky headlands connected by fine curving sandy beaches. Its natural

  6. Modeling Agassiz's Desert Tortoise Population Response to Anthropogenic Stressors

    Science.gov (United States)

    Mojave Desert tortoise (Gopherus agassizii) populations are exposed to a variety of anthropogenic threats, which vary in nature, severity, and frequency. Tortoise management in conservation areas can be compromised when the relative importance of these threats is not well underst...

  7. Final Critical Habitat for the Desert pupfish (Cyprinodon macularius)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — To provide the user with a general idea of areas where final critical habitat for desert pupfish (Cyprinodon macularius) occur based on the description provided in...

  8. Oregon High Desert Interpretive Center : Economic feasibility and impact analysis

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a proposal to construct a High Desert Interpretive Center to inform visitors to Harney County, Oregon of the opportunities for education, recreation and...

  9. Annual plants in arid and semi-arid desert regions

    Institute of Scientific and Technical Information of China (English)

    Xuehua LI; Xiaolan LI; Deming JIANG; Zhimin LIU; Qinghe YU

    2008-01-01

    Annual plants are the main vegetation in arid and semi-arid desert regions.Because of their unique traits,they are the optimal experimental subjects for eco-logical studies.In this article,we summarize annual plants' seed germination strategies,seedling adaptability mechanism to environments,seed dispersal,and soil seed banks.We also discuss the biotic and abiotic factors affecting the composition and dynamics of annual plant populations and communities.Because annual plants have important ecological functions in desert vegetation systems,this study on annual plants will be of great bene-fit to the conservation and restoration of desert ecosys-tems,the rational utilization of resources,and the sustainable development of desert regions.

  10. Final Critical Habitat for the Desert yellowhead (Yermo xanthocephalus)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — These data identify, in general, the areas where final critical habitat for the Desert yellowhead (Yermo xanthocephalus) occur. The geographic extent includes...

  11. Species status assessment for the Sonoran desert tortoise

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Sonoran desert tortoise (Gopherus morafkai) occurs in various habitat types in Arizona and northern Mexico. It was made a candidate for listing in 2010 by the...

  12. Reading the Cosmic Landscape: An Observatory in the Nevada Desert

    Science.gov (United States)

    McDonald, Hilary Jane

    This thesis aims to restore value to the phenomenological experience of the desert through architecture, exploring the desert as a physical, cultural and experiential landscape that ideally lends itself to the study of astronomy and to a greater understanding of a universal order. This project will create a recreational observatory allowing amateur observers to study the skies. The observatory will be located on the desert peak of Mount Washington, located in Great Basin National Park in Nevada. It will provide a venue for the astronomy-focused activities which already exist within the park, and will serve as a destination highlighting the cosmic properties of the desert. This thesis proposes that architecture can play a role in realizing the essential qualities of this unique landscape and can enhance the study of astronomy as an endeavor that goes beyond science to access a greater understanding of the human condition.

  13. Final Critical Habitat for the Desert Tortoise (Gopherus agassizii)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — To provide the user with a general idea of areas where final critical habitat for desert tortoise (Gopherus agassizii) occur based on the description provided in...

  14. Vegetation - Anza-Borrego Desert State Park [ds165

    Data.gov (United States)

    California Department of Resources — The Anza Borrego Desert State Park (ABDSP) Vegetation Map depicts vegetation within the Park and its surrounding environment. The map was prepared by the Department...

  15. Proposal for multi-agency facility : High Desert Interagency Partnership

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a proposal to construct a multi-agency facility to house the High Desert Interagency Partnership. The facility would be on federally owned land in Hines,...

  16. Role of remote sensing in desert locust early warning

    Science.gov (United States)

    Cressman, Keith

    2013-01-01

    Desert locust (Schistocerca gregaria, Forskål) plagues have historically had devastating consequences on food security in Africa and Asia. The current strategy to reduce the frequency of plagues and manage desert locust infestations is early warning and preventive control. To achieve this, the Food and Agriculture Organization of the United Nations operates one of the oldest, largest, and best-known migratory pest monitoring systems in the world. Within this system, remote sensing plays an important role in detecting rainfall and green vegetation. Despite recent technological advances in data management and analysis, communications, and remote sensing, monitoring desert locusts and preventing plagues in the years ahead will continue to be a challenge from a geopolitical and financial standpoint for affected countries and the international donor community. We present an overview of the use of remote sensing in desert locust early warning.

  17. Assessing the Benefits of Urban Forestry in Mojave Desert Communities

    Science.gov (United States)

    As the climate and environment change due to human activity, an understanding of the existing natural resources becomes paramount. Urban forests of Mojave Desert communities have the potential to reduce air pollution, heat island effects, and energy consumption. Regions throughou...

  18. Ecophysiology of two Sonoran Desert evergreen shrubs during extreme drought

    Science.gov (United States)

    Recent drought across the arid Southwest US may be especially problematic for evergreen desert species that maintain leaves through dry periods. In July, 2002 we compared the ecophysiogical performance of the microphyllous creosotebush (Larrea tridentata) to broadleaved jojoba (Simmondisa chinensis...

  19. The potential of energy farming in the southeastern California desert

    Science.gov (United States)

    Lew, V.

    1980-04-01

    The use of energy forms to provide future sources of energy for California is considered. Marginal desert lands in southeastern California are proposed for the siting of energy farms using acacia, eucalyptus, euphorbia, guayule, jojoba, mesquite, or tamarisk.

  20. Recently active reverse faulting in the Atacama Basin area, northern Chile: Implications for the distribution of convergence across the western South America plate boundary

    Science.gov (United States)

    Shyu, J. H.; Gonzalez, G.; Simons, M.; Aron, F.; Veloso, A.

    2007-12-01

    The western South American margin is one of the most active continental plate boundaries in the world. The ongoing convergence between the Nazca plate, or formerly the Farallon plate, and the South American plate produced the wide deformation belt of the Andes. In order to obtain more information about the active deformations in the central Andean belt to better understand the current distribution of convergence across the orogen, we attempted to map major structures that appear to be active recently by their topographic expressions using SRTM DEM and Landsat satellite images, followed by field observations. Results of our mapping show that there are many reverse faults that may be recently active in the area surrounding the Atacama Basin, in the Preandean Depression in northern Chile. These include a series of active reverse faults and related folds at the southeastern corner of the Atacama Basin, a major fold system that may be produced by an underlying fault just east of the basin, and a series of folds that forms the Cordillera de la Sal in the northern and western part of the basin. At the southeastern corner of the Atacama Basin, several geomorphic features indicate that at least some of the structures there have been active quite recently, including small drainages that cut through the folds and form active alluvial fans. Similar features of active river incision across folds are also present in the northern part of the basin. The fold system east of the basin may be one of the most important structures in the area. Deformed lava flows and deflected drainages indicate that this structure has been active recently, and growth strata near the fold suggest that it has been active for several myr. If so, the structure may be a major reverse fault system that defines the eastern boundary of the Atacama Basin, and may thus be an important onland structure that is responsible for absorbing part of the plate convergence.

  1. A Future for the Past of Desert Vernacular Architecture

    OpenAIRE

    Dabaieh, Marwa

    2011-01-01

    Desert vernacular architecture has always been the product of a sustainable building cycle. People inherited the traditional way of building from their ancestors and the knowledge was transferred and developed from one generation to another. Inhabitants responded to their environment and climate through trial and error in a way that satisfied their needs and aspirations to create a developing building tradition. This natural and cultural cycle is about to disappear in many desert vernacular s...

  2. Abiotic Factors Shape Microbial Diversity in Sonoran Desert Soils

    OpenAIRE

    Andrew, David R.; Fitak, Robert R.; Munguia-Vega, Adrian; Racolta, Adriana; Martinson, Vincent G.; Dontsova, Katerina

    2012-01-01

    High-throughput, culture-independent surveys of bacterial and archaeal communities in soil have illuminated the importance of both edaphic and biotic influences on microbial diversity, yet few studies compare the relative importance of these factors. Here, we employ multiplexed pyrosequencing of the 16S rRNA gene to examine soil- and cactus-associated rhizosphere microbial communities of the Sonoran Desert and the artificial desert biome of the Biosphere2 research facility. The results of our...

  3. Contraction of the Gobi Desert, 2000–2012

    Directory of Open Access Journals (Sweden)

    Troy Sternberg

    2015-01-01

    Full Text Available Deserts are critical environments because they cover 41% of the world’s land surface and are home to 2 billion residents. As highly dynamic biomes desert expansion and contraction is influenced by climate and anthropogenic factors with variability being a key part of the desertification debate across dryland regions. Evaluating a major world desert, the Gobi in East Asia, with high resolution satellite data and the meteorologically-derived Aridity Index from 2000 to 2012 identified a recent contraction of the Gobi. The fluctuation in area, primarily driven by precipitation, is at odds with numerous reports of human-induced desertification in Mongolia and China. There are striking parallels between the vagueness in defining the Gobi and the imprecision and controversy surrounding the Sahara desert’s southern boundary in the 1980s and 1990s. Improved boundary definition has implications fGobi; desert boundary; expansion and contraction; Aridity Index; NDVI; Mongolia; China or understanding desert “greening” and “browning”, human action and land use, ecological productivity and changing climate parameters in the region. The Gobi’s average area of 2.3 million km2 in the 21st century places it behind only the Sahara and Arabian deserts in size.

  4. Making silica rock coatings in the lab: synthetic desert varnish

    Science.gov (United States)

    Perry, Randall S.; Kolb, Vera M.; Philip, Ajish I.; Lynne, Bridget Y.; McLoughlin, Nicola; Sephton, Mark; Wacey, David; Green, Owen R.

    2005-09-01

    Desert varnish and silica rock coatings have perplexed investigators since Humboldt and Darwin. They are found in arid regions and deserts on Earth but the mechanism of their formation remains challenging (see Perry et al. this volume). One method of researching this is to investigate natural coatings, but another way is to attempt to produce coatings in vitro. Sugars, amino acids, and silicic acid, as well as other organic and (bio)organic compounds add to the complexity of naturally forming rock coatings. In the lab we reduced the complexity of the natural components and produced hard, silica coatings on basaltic chips obtained from the Mojave Desert. Sodium silicate solution was poured over the rocks and continuously exposed to heat and/or UV light. Upon evaporation the solutions were replenished. Experiments were performed at various pH's. The micro-deposits formed were analyzed using optical, SEM-EDAX, and electron microprobe. The coatings formed are similar in hardness and composition to silica glazes found on basalts in Hawaii as well as natural desert varnish found in US southwest deserts. Thermodynamic mechanisms are presented showing the theoretical mechanisms for overcoming energy barriers that allow amorphous silica to condense into hard coatings. This is the first time synthetic silica glazes that resemble natural coatings in hardness and chemical composition have been successfully reproduced in the laboratory, and helps to support an inorganic mechanism of formation of desert varnish as well as manganese-deficient silica glazes.

  5. Swell prediction for the East Korean coast

    OpenAIRE

    J. H. Yuk; Kim, K. O.; Choi, B. H.; K. T. Jung

    2013-01-01

    Long-period abnormally high swell waves have been generated in the East Sea near Hokkaido, Japan, in winter during the atmospheric depression. These waves, named Yorimawari in Japanese, occasionally attack the coasts of both Korea and Japan. Waves significantly higher than normal years were recorded along the east Korean coast in 2006. In 2008, the swell caused considerable damages in Toyama and the Niigata coastal area of Japan and in Anmok east coast of Korea. This paper attempts to hindcas...

  6. A slow-slipping active fold and thrust system at the SE corner of the Atacama basin, northern Chile

    Science.gov (United States)

    Lin, Y.; Shyu, J. H.; González, G.

    2009-12-01

    The western South American offshore is one of the major active convergent plate boundaries in the world, where the Nazca plate is subducting northeastward beneath the South American plate at a rate of about 84 mm/yr. Despite of this rapid plate convergence, the forearc region of western Andes does not seem to undergo large deformation at present. In order to understand the characteristics and mechanisms of active forearc deformation related to the plate convergence, we investigated tectono-geomorphic features in the area of Tilocalar, near the SE margin of the Atacama Basin in northern Chile, where active structures have been previously identified. To map topographic features produced by active structures, we used a combination of several remote-sensing data sets, including digital elevation models (DEM) made from Shuttle Radar Topographic Mission (SRTM), as well as higher resolution ASTER and QuickBird satellite images. Detailed geomorphic surveys using real time kinematic (RTK) GPS are carried out in the field to obtain high-resolution topographic profiles across these features. We also performed 40Ar/39Ar dating of deformed volcanic rocks in order to determine the long-term slip rates of the active structures. The hyper-aridity of the Atacama Basin results in extremely low erosion and sedimentation rates in the area. As a result, the present relief of land surface is mostly produced by neotectonic activity, and can be used as deformation marker. In the Tilocalar area, several N-S trending ridges are present. These ridges, generally several tens of meters high, are likely formed by asymmetric anticlines or monoclines with steep forelimbs facing east, and these folds are likely fault-propagation folds produced by underlying thrust faults. We suggest that these faults merge at depth to become a major active thrust system. From 40Ar/39Ar plateau ages, we found that the surface ignimbrites mostly deposited in latest Pliocene (2.3~4.3 Ma). If the structures have been

  7. U.S. Coast Guard (USCG) Districts

    Data.gov (United States)

    Department of Homeland Security — This layer is a polygonal dataset that represents land and maritime boundaries for each representative United States Coast Guard district, which includes district...

  8. Respondence and feedback of modern sand deserts to climate change--A case study in Gurbantunggut Desert

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The research on the respondence and feedback of modern sand deserts to the climate change is an important component part in the studies on the global climate change. Deserts respond to the climate change, meanwhile, they affect the climate with their feedback of peculiar environment during the respondence. Many researches on desert climate have been carried out at home and abroad. However, there is little research on the respondence and feedback of modern fixed, semi-fixed and mobile deserts in arid areas to the climate change, in which the factor analysis as well as the parameter changing effects is especially the difficult problem all along. In this note, the parameters of the respondence and feedback of Gurbantunggut Desert to the climate change are measured and analyzed, some variable parameters of water-heat exchange are obtained, and a numerical model of desertification is developed according to a series of climate change of about 40 years and the variable relations of meteorological and physical features of the sand surface in Gurbantunggut Desert.

  9. Marine archaeological investigations along the Saurashtra coast, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh; Tripati, S.

    . Foreign travellers have mentioned the names of active ports on the Saurashtra coast since the early historical period. During the medieval period this coast has witnessed hectic maritime activities and international trade and commerce. Marine...

  10. Searching for Life in Death Valley (and Other Deserts) - Microchemical Investigations on Desert Varnish

    Science.gov (United States)

    Andreae, M. O.; Al-Amri, A. M.; Jochum, K. P.; Kappl, M.; Kilcoyne, A. D.; Macholdt, D.; Müller, M.; Pöhlker, C.; Weber, B.; Weigand, M.

    2014-12-01

    Desert varnishes are thin, shiny, blackish to brown coatings frequently found on the surfaces of exposed rocks in deserts around the globe. They have been proposed as terrestrial analogues of superficial hematite enrichments observed on Mars. While the first scientific studies of such varnishes go back to Darwin and von Humboldt, and intensive studies by a variety of techniques have been conducted over the last few decades, their origin is still a matter of debate. Microscopic and molecular studies have shown the presence of fungi and bacteria, but it is still unclear whether they are involved in the formation of the varnish material or just opportunistic colonizers on available surfaces. We have analysed samples of desert varnish from sites in Death Valley, the Mojave Desert, the Negev of Israel, Central Saudi Arabia, and the Succulent Karoo by a variety of microanalytical techniques. Measurements by UV-femtosecond Laser Ablation Inductively Coupled Plasma Mass Spectrometry show enrichments of manganese, iron, barium and other elements. Isotopic and trace chemical signatures show that these enriched elements cannot originate from the rocks that form the substrate on which the crusts have been deposited, but most likely are the result of (bio?)chemical transformation of windblown material. For a more detailed investigation of the internal structure of the crusts, we prepared ultra-thin sections (~100 nm) using focused ion beam slicing and analysed them by Scanning Transmission X-ray Microscopy with Near-Edge X-ray Absorption Fine Structure spectroscopy (STXM-NEXAFS). This technique revealed layered or chaotic structures consisting of alternating Mn and Fe-rich zones. Some of these layers are enriched in organic carbon with spectral features dominated by aromatic and carboxylate functionalities, indicating a biological origin of some of the crust material. Some crusts also show cavities that are lined with similar organic material. Since the age of these crusts is

  11. Continuous measurements of greenhouse gases and atmospheric oxygen at the Namib Desert Atmospheric Observatory

    Directory of Open Access Journals (Sweden)

    E. J. Morgan

    2015-02-01

    Full Text Available A new coastal background site has been established for observations of greenhouse gases (GHGs in the central Namib Desert at Gobabeb, Namibia. The location of the site was chosen to provide observations for a data-poor region in the global sampling network for GHGs. Semi-automated, continuous measurements of carbon dioxide, methane, nitrous oxide, carbon monoxide, atmospheric oxygen, and basic meteorology are made at a height of 21 m a.g.l., 50 km from the coast at the northern border of the Namib Sand Sea. Atmospheric oxygen is measured with a differential fuel cell analyzer (DFCA. Carbon dioxide and methane are measured with an early-model cavity ring-down spectrometer (CRDS; nitrous oxide and carbon monoxide are measured with an off-axis integrated cavity output spectrometer (OA-ICOS. Instrument-specific water corrections are employed for both the CRDS and OA-ICOS instruments in lieu of drying. The performance and measurement uncertainties are discussed in detail. As the station is located in a remote desert environment, there are some particular challenges, namely fine dust, high diurnal temperature variability, and minimal infrastructure. The gas handling system and calibration scheme were tailored to best fit the conditions of the site. The CRDS and DFCA provide data of acceptable quality when base requirements for operation are met, specifically adequate temperature control in the laboratory and regular supply of electricity. In the case of the OA-ICOS instrument, performance is significantly improved through the implementation of a drift correction through frequent measurements of a working tank.

  12. Continuous measurements of greenhouse gases and atmospheric oxygen at the Namib Desert Atmospheric Observatory

    Science.gov (United States)

    Morgan, E. J.; Lavrič, J. V.; Seifert, T.; Chicoine, T.; Day, A.; Gomez, J.; Logan, R.; Sack, J.; Shuuya, T.; Uushona, E. G.; Vincent, K.; Schultz, U.; Brunke, E.-G.; Labuschagne, C.; Thompson, R. L.; Schmidt, S.; Manning, A. C.; Heimann, M.

    2015-02-01

    A new coastal background site has been established for observations of greenhouse gases (GHGs) in the central Namib Desert at Gobabeb, Namibia. The location of the site was chosen to provide observations for a data-poor region in the global sampling network for GHGs. Semi-automated, continuous measurements of carbon dioxide, methane, nitrous oxide, carbon monoxide, atmospheric oxygen, and basic meteorology are made at a height of 21 m a.g.l., 50 km from the coast at the northern border of the Namib Sand Sea. Atmospheric oxygen is measured with a differential fuel cell analyzer (DFCA). Carbon dioxide and methane are measured with an early-model cavity ring-down spectrometer (CRDS); nitrous oxide and carbon monoxide are measured with an off-axis integrated cavity output spectrometer (OA-ICOS). Instrument-specific water corrections are employed for both the CRDS and OA-ICOS instruments in lieu of drying. The performance and measurement uncertainties are discussed in detail. As the station is located in a remote desert environment, there are some particular challenges, namely fine dust, high diurnal temperature variability, and minimal infrastructure. The gas handling system and calibration scheme were tailored to best fit the conditions of the site. The CRDS and DFCA provide data of acceptable quality when base requirements for operation are met, specifically adequate temperature control in the laboratory and regular supply of electricity. In the case of the OA-ICOS instrument, performance is significantly improved through the implementation of a drift correction through frequent measurements of a working tank.

  13. Assaying Visual Memory in the Desert Locust

    Directory of Open Access Journals (Sweden)

    Senne Dillen

    2015-04-01

    Full Text Available The involvement of associative learning cues has been demonstrated in several stages of feeding and food selection. Short neuropeptide F (sNPF, an insect neuropeptide whose effects on feeding behavior have previously been well established, may be one of the factors bridging feeding and learning behavior. Recently, it was shown in Drosophila melanogaster that the targeted reduction of Drome-sNPF transcript levels significantly reduced sugar-rewarded olfactory memory. While Drosophila mainly relies on olfactory perception in its food searching behavior, locust foraging behavior is likely to be more visually orientated. Furthermore, a feeding-dependent regulation of Schgr-sNPF transcript levels has previously been observed in the optic lobes of the locust brain, suggesting a possible involvement in visual perception of food and visual associative memory in this insect species. In this study, we describe the development of a robust and reproducible assay allowing visual associative memory to be studied in the desert locust, Schistocerca gregaria. Furthermore, we performed an exploratory series of experiments, studying the role of Schgr-sNPF in this complex process.

  14. Assaying Visual Memory in the Desert Locust.

    Science.gov (United States)

    Dillen, Senne; Chen, Ziwei; Broeck, Jozef Vanden

    2015-01-01

    The involvement of associative learning cues has been demonstrated in several stages of feeding and food selection. Short neuropeptide F (sNPF), an insect neuropeptide whose effects on feeding behavior have previously been well established, may be one of the factors bridging feeding and learning behavior. Recently, it was shown in Drosophila melanogaster that the targeted reduction of Drome-sNPF transcript levels significantly reduced sugar-rewarded olfactory memory. While Drosophila mainly relies on olfactory perception in its food searching behavior, locust foraging behavior is likely to be more visually orientated. Furthermore, a feeding-dependent regulation of Schgr-sNPF transcript levels has previously been observed in the optic lobes of the locust brain, suggesting a possible involvement in visual perception of food and visual associative memory in this insect species. In this study, we describe the development of a robust and reproducible assay allowing visual associative memory to be studied in the desert locust, Schistocerca gregaria. Furthermore, we performed an exploratory series of experiments, studying the role of Schgr-sNPF in this complex process. PMID:26463192

  15. Copper isotope fractionation by desert shrubs

    Energy Technology Data Exchange (ETDEWEB)

    Navarrete, Jesica U., E-mail: jnavarrete2@miners.utep.edu [University of Texas at El Paso, Department of Geological Sciences, 500 W. University Ave, El Paso, TX 79968 (United States); Viveros, Marian; Ellzey, Joanne T. [University of Texas at El Paso, Department of Biological Sciences, El Paso, TX 79968 (United States); Borrok, David M. [University of Texas at El Paso, Department of Geological Sciences, 500 W. University Ave, El Paso, TX 79968 (United States)

    2011-06-15

    Copper has two naturally occurring stable isotopes of masses 63 and 65 which can undergo mass dependent fractionation during various biotic and abiotic chemical reactions. These interactions and their resulting Cu isotope fractionations can be used to determine the mechanisms involved in the cycling of Cu in natural systems. In this study, Cu isotope changes were investigated at the organismal level in the metal-accumulating desert plant, Prosopis pubescens. Initial results suggest that the lighter Cu isotope was preferentially incorporated into the leaves of the plant, which may suggest that Cu was actively transported via intracellular proteins. The roots and stems show a smaller degree of Cu isotope fractionation and the direction and magnitude of the fractionations was dependent upon the levels of Cu exposure. Based on this and previous work with bacteria and yeast, a trend is emerging that suggests the lighter Cu isotope is preferentially incorporated into biological components, while the heavier Cu isotope tends to become enriched in aqueous solutions. In bacteria, plants and animals, intracellular Cu concentrations are strictly regulated via dozens of enzymes that can bind, transport, and store Cu. Many of these enzymes reduce Cu(II) to Cu(I). These initial results seem to fit into a broader picture of Cu isotope cycling in natural systems where oxidation/reduction reactions are fundamental in controlling the distributions of Cu isotopes.

  16. AIS spectra of desert shrub canopies

    Science.gov (United States)

    Murray, R.; Isaacson, D. L.; Schrumpf, B. J.; Ripple, W. J.; Lewis, A. J.

    1986-01-01

    Airborne Imaging Spectrometer (AIS) data were collected 30 August 1985 from a desert shrub community in central Oregon. Spectra from artificial targets placed on the test site and from bare soil, big sagebrush (Artemesia tridentata wyomingensis), silver sagebrush (Artemesia cana bolander), and exposed volcanic rocks were studied. Spectral data from grating position 3 (tree mode) were selected from 25 ground positions for analysis by Principal Factor Analysis (PFA). In this grating position, as many as six factors were identified as significant in contributing to spectral structure. Channels 74 through 84 (tree mode) best characterized between-class differences. Other channels were identified as nondiscriminating and as associated with such errors as excessive atmospheric absorption and grating positin changes. The test site was relatively simple with the two species (A. tridentata and A. cana) representing nearly 95% of biomass and with only two mineral backgrounds, a montmorillonitic soil and volcanic rocks. If, as in this study, six factors of spectral structure can be extracted from a single grating position from data acquired over a simple vegetation community, then AIS data must be considered rich in information-gathering potential.

  17. Status of the Desert Fireball Network

    Science.gov (United States)

    Devillepoix, H. A. R.; Bland, P. A.; Towner, M. C.; Cupák, M.; Sansom, E. K.; Jansen-Sturgeon, T.; Howie, R. M.; Paxman, J.; Hartig, B. A. D.

    2016-01-01

    A meteorite fall precisely observed from multiple locations allows us to track the object back to the region of the Solar System it came from, and sometimes link it with a parent body, providing context information that helps trace the history of the Solar System. The Desert Fireball Network (DFN) is built in arid areas of Australia: its observatories get favorable observing conditions, and meteorite recovery is eased thanks to the mostly featureless terrain. After the successful recovery of two meteorites with 4 film cameras, the DFN has now switched to a digital network, operating 51 cameras, covering 2.5 million km2 of double station triangulable area. Mostly made of off-the-shelf components, the new observatories are cost effective while maintaining high imaging performance. To process the data (~70TB/month), a significant effort has been put to writing an automated reduction pipeline so that all events are reduced with little human intervention. Innovative techniques have been implemented for this purpose: machine learning algorithms for event detection, blind astrometric calibration, and particle filter simulations to estimate both physical properties and state vector of the meteoroid. On 31 December 2015, the first meteorite from the digital systems was recovered: Murrili (the 1.68 kg H5 ordinary chondrite was observed to fall on 27 November 2015). Another 11 events have been flagged as potential meteorites droppers, and are to be searched in the coming months.

  18. Submicron desert dusts: A sandblasting process

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, L.; Bergametti, G. (Universite Paris VII (France)); Coude-Gaussen, G.; Rognon, P. (Universite Pierre et Marie Curie, Paris (France))

    1990-08-20

    Mass size distributions of the major elements of the mineral aerosol of northern Sahara were obtained from measurements carried out with an inertial cascade impactor. A fitting procedure by data inversion was applied to these data. This technique considers the major mechanisms of nonideal behavior such as particle bounce-off, wall losses and cross sensitivity which affect the accuracy of impactor measurements of aerosol size distribution. Accurate size distributions of Saharan aerosol (range 0.1-20 {mu}m) were so obtained for different conditions of soil mobilization. These measurements, coupled with wind speed information, show the shape of the size distribution for desert aerosols in the considered range to be characterized by a similar pattern with a common mode of particles having diameter between 1 and 20 {mu}m whatever the weather conditions. A second mass peak of submicron particles appears when the wind speed increases above the threshold value for erosion. Scanning electron microscope photographs indicate that the whole granulometric spectrum of the sampled aerosol between 0.1 and 20 {mu}m mainly consists of clay easily disaggregated by sandblasting. The common origin of submicron particles with those between 1 and 20 {mu}m is established by showing the similar composition of dusts in the both modes. The results suggest that the presence of submicron mineral particles during dusty and sandstorm conditions is consistent with a sandblasting process.

  19. The Atacama Cosmology Telescope: Sunyaev Zel'dovich Selected Galaxy Clusters at 148 GHz in the 2008 Survey

    CERN Document Server

    Marriage, T A; Ade, P A R; Aguirre, P; Amiri, M; Appel, J W; Barrientos, L F; Battistelli, E S; Bond, J R; Brown, B; Burger, B; Chervenak, J; Das, S; Devlin, M J; Dicker, S R; Doriese, W B; Dunkley, J; Dunner, R; Essinger-Hileman, T; Fisher, R P; Fowler, J W; Hajian, A; Halpern, M; Hasselfield, M; Hern'andez-Monteagudo, C; Hilton, G C; Hilton, M; Hincks, A D; Hlozek, R; Huffenberger, K M; Hughes, D H; Hughes, J P; Infante, L; Irwin, K D; Juin, J B; Kaul, M; Klein, J; Kosowsky, A; Lau, J M; Limon, M; Lin, Y -T; Lupton, R H; Marsden, D; Martocci, K; Mauskopf, P; Menanteau, F; Moodley, K; Moseley, H; Netterfield, C B; Niemack, M D; Nolta, M R; Page, L A; Parker, L; Partridge, B; Quintana, H; Reese, E D; Reid, B; Sehgal, N; Sherwin, B D; Sievers, J; Spergel, D N; Staggs, S T; Swetz, D S; Switzer, E R; Thornton, R; Trac, H; Tucker, C; Warne, R; Wilson, G; Wollack, E; Zhao, Y

    2010-01-01

    We report on twenty-three clusters detected blindly as Sunyaev-Zel'dovich (SZ) decrements in a 148 GHz, 455 square-degree map of the southern sky made with data from the Atacama Cosmology Telescope 2008 observing season. All SZ detections have confirmed optical counterparts. Ten of the clusters are new discoveries. One newly discovered cluster, ACT-CL J0102-4915, with a redshift of 0.75 (photometric), has an SZ decrement comparable to the most massive systems at lower redshifts. Simulations of the cluster recovery method reproduce the sample purity measured by optical follow-up. In particular, for clusters detected with a signal-to-noise ratio greater than six, simulations are consistent with optical follow-up that demonstrated this subsample is 100% pure. The simulations further imply that the total sample is 80% complete for clusters with mass in excess of 6x10^14 solar masses referenced to the cluster volume characterized by five hundred times the critical density. The Compton y -- X-ray luminosity mass co...

  20. The Atacama Cosmology Telescope: Sunyaev-Zel'dovich Selected Galaxy Clusters at 148 GHz from Three Seasons of Data

    CERN Document Server

    Hasselfield, Matthew; Marriage, Tobias A; Addison, Graeme E; Barrientos, L Felipe; Battaglia, Nick; Battistelli, Elia S; Bond, J Richard; Crichton, Devin; Das, Sudeep; Devlin, Mark J; Dicker, Simon R; Dunkley, Joanna; Dunner, Rolando; Fowler, Joseph W; Gralla, Megan B; Hajian, Amir; Halpern, Mark; Hincks, Adam D; Hlozek, Renée; Hughes, John P; Infante, Leopoldo; Irwin, Kent D; Kosowsky, Arthur; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Partridge, Bruce; Reese, Erik D; Schmitt, Benjamin L; Sehgal, Neelima; Sherwin, Blake D; Sievers, Jon; Sifón, Cristóbal; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Trac, Hy; Wollack, Edward J

    2013-01-01

    [Abridged] We present a catalog of 68 galaxy clusters, of which 19 are new discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the Atacama Cosmology Telescope (ACT) survey of 504 square degrees on the celestial equator. A subsample of 48 clusters within the 270 square degree region overlapping SDSS Stripe 82 is estimated to be 90% complete for M_500c > 4.5e14 Msun and 0.15 < z < 0.8. While matched filters are used to detect the clusters, the sample is studied further through a "Profile Based Amplitude Analysis" using a single filter at a fixed \\theta_500 = 5.9' angular scale. This new approach takes advantage of the "Universal Pressure Profile" (UPP) to break the degeneracy between the cluster extent (R_500) and the integrated Compton parameter (Y_500). The UPP scalings are found to be nearly identical to an adiabatic model, while a model incorporating non-thermal pressure better matches dynamical mass measurements and masses from the South Pole Telescope. A complete, high signal ...

  1. The Atacama Cosmology Telescope: Physical Properties of Sunyaev-Zel'dovich Effect Clusters on the Celestial Equator

    CERN Document Server

    Menanteau, Felipe; Barrientos, L Felipe; Battaglia, Nicholas; Bond, J Richard; Crichton, Devin; Das, Sudeep; Devlin, Mark J; Dünner, Rolando; Gralla, Megan; Hajian, Amir; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D; Hughes, John P; Infante, Leopoldo; Kosowsky, Arthur; Marriage, Tobias A; Marsden, Danica; Moodley, Kavilan; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Partridge, Bruce; Reese, Erik D; Schmitt, Benjamin L; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Switzer, Eric; Wollack, Edward J

    2012-01-01

    We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich Effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 square degrees centered on the celestial equator, is divided into two regions. The main region uses 270 square degrees of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed observations with the Apache Point Observatory 3.5-meter telescope. We confirm a total of 49 clusters to z~1.3, of which 22 (all at z>0.55) are new discoveries. For the second region the regular-depth SDSS imaging allows us to confirm 19 more clusters up to z~0.7, of which 10 systems are new. We present the optical richness, photometric redshifts, and separation between the SZ position and the brightest cluster galaxy (BCG). We find no significant offset between the cluster SZ centroid and BCG location and a weak correlation between optical richne...

  2. The Atacama Cosmology Telescope: A Measurement of the 600< ell <8000 Cosmic Microwave Background Power Spectrum at 148 GHz

    CERN Document Server

    Fowler, J W; Ade, P A R; Aguirre, P; Amiri, M; Appel, J W; Barrientos, L F; Battistelli, E S; Bond, J R; Brown, B; Burger, B; Chervenak, J; Das, S; Devlin, M J; Dicker, S R; Doriese, W B; Dunkley, J; Dünner, R; Essinger-Hileman, T; Fisher, R P; Hajian, A; Halpern, M; Hasselfield, M; Hernández-Monteagudo, C; Hilton, G C; Hilton, M; Hincks, A D; Hlozek, R; Huffenberger, K M; Hughes, D H; Hughes, J P; Infante, L; Irwin, K D; Jimenez, R; Juin, J B; Kaul, M; Klein, J; Kosowsky, A; Lau, J M; Limon, M; Lin, Y -T; Lupton, R H; Marriage, T A; Marsden, D; Martocci, K; Mauskopf, P; Menanteau, F; Moodley, K; Moseley, H; Netterfield, C B; Niemack, M D; Nolta, M R; Page, L A; Parker, L; Partridge, B; Quintana, H; Reid, B; Sehgal, N; Sievers, J; Spergel, D N; Staggs, S T; Swetz, D S; Switzer, E R; Thornton, R; Trac, H; Tucker, C; Verde, L; Warne, R; Wilson, G; Wollack, E; Zhao, Y

    2010-01-01

    We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) radiation observed at 148 GHz. The measurement uses maps with 1.4' angular resolution made with data from the Atacama Cosmology Telescope (ACT). The observations cover 228 square degrees of the southern sky, in a 4.2-degree-wide strip centered on declination 53 degrees South. The CMB at arcminute angular scales is particularly sensitive to the Silk damping scale, to the Sunyaev-Zel'dovich (SZ) effect from galaxy clusters, and to emission by radio sources and dusty galaxies. After masking the 108 brightest point sources in our maps, we estimate the power spectrum between 600 < \\ell < 8000 using the adaptive multi-taper method to minimize spectral leakage and maximize use of the full data set. Our absolute calibration is based on observations of Uranus. To verify the calibration and test the fidelity of our map at large angular scales, we cross-correlate the ACT map to the WMAP map and recover the WMAP power sp...

  3. The Atacama Cosmology Telescope: the stellar content of galaxy clusters selected using the Sunyaev-Zel'dovich effect

    CERN Document Server

    Hilton, Matt; Sifón, Cristóbal; Baker, Andrew J; Barrientos, L Felipe; Battaglia, Nicholas; Bond, J Richard; Crichton, Devin; Das, Sudeep; Devlin, Mark J; Gralla, Megan; Hajian, Amir; Hincks, Adam D; Hughes, John P; Infante, Leopoldo; Irwin, Kent D; Kosowsky, Arthur; Lin, Yen-Ting; Marriage, Tobias A; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D; Nolta, Mike R; Page, Lyman A; Reese, Erik D; Sievers, Jon; Spergel, David N; Wollack, Edward J

    2013-01-01

    We present a first measurement of the stellar mass component of galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect, using 3.6 um and 4.5 um photometry from the Spitzer Space Telescope. Our sample consists of 14 clusters detected by the Atacama Cosmology Telescope (ACT), which span the redshift range 0.27 < z < 1.07 (median z = 0.50), and have dynamical mass measurements, accurate to about 30 per cent, with median M500 = 6.9 x 10^{14} MSun. We measure the 3.6 um and 4.5 um galaxy luminosity functions, finding the characteristic magnitude (m*) and faint-end slope (alpha) to be similar to those for IR-selected cluster samples. We perform the first measurements of the scaling of SZ-observables (Y500 and y0) with both brightest cluster galaxy (BCG) stellar mass and total cluster stellar mass (M500star). We find a significant correlation between BCG stellar mass and Y500 (E(z)^{-2/3} DA^2 Y500 ~ M*^{1.2 +/- 0.6}), although we are not able to obtain a strong constraint on the slope of the relation...

  4. The Atacama Cosmology Telescope: Dynamical Masses for 44 SZ-Selected Galaxy Clusters over 755 Square Degrees

    Science.gov (United States)

    Sifon, Cristobal; Battaglia, Nick; Hasselfield, Matthew; Menanteau, Felipe; Barrientos, L. Felipe; Bond, J. Richard; Crichton, Devin; Devlin, Mark J.; Dunner, Rolando; Hilton, Matt; Wollack, Edward J.

    2016-01-01

    We present galaxy velocity dispersions and dynamical mass estimates for 44 galaxy clusters selected via the Sunyaev-Zeldovich (SZ) effect by the Atacama Cosmology Telescope. Dynamical masses for 18 clusters are reported here for the first time. Using N-body simulations, we model the different observing strategies used to measure the velocity dispersions and account for systematic effects resulting from these strategies. We find that the galaxy velocity distributions may be treated as isotropic, and that an aperture correction of up to 7 per cent in the velocity dispersion is required if the spectroscopic galaxy sample is sufficiently concentrated towards the cluster centre. Accounting for the radial profile of the velocity dispersion in simulations enables consistent dynamical mass estimates regardless of the observing strategy. Cluster masses M200 are in the range (1 - 15) times 10 (sup 14) Solar Masses. Comparing with masses estimated from the SZ distortion assuming a gas pressure profile derived from X-ray observations gives a mean SZ-to-dynamical mass ratio of 1:10 plus or minus 0:13, but there is an additional 0.14 systematic uncertainty due to the unknown velocity bias; the statistical uncertainty is dominated by the scatter in the mass-velocity dispersion scaling relation. This ratio is consistent with previous determinations at these mass scales.

  5. Subaru weak-lensing measurement of a z = 0.81 cluster discovered by the Atacama Cosmology Telescope Survey

    CERN Document Server

    Miyatake, Hironao; Takada, Masahiro; Mandelbaum, Rachel; Mineo, Sogo; Aihara, Hiroaki; Spergel, David N; Bickerton, Steven J; Bond, J Richard; Hajian, Amir; Hilton, Matt; Hincks, Adam D; Hughes, John P; Infante, Leopoldo; Lin, Yen-Ting; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Menanteau, Felipe; Miyazaki, Satoshi; Moodley, Kavilan; Niemack, Michael D; Oguri, Masamune; Price, Paul A; Reese, Erik D; Sifon, Cristobal; Wollack, Edward J; Yasuda, Naoki

    2013-01-01

    We present a Subaru weak lensing measurement of ACT-CL J0022.2-0036, one of the most luminous, high-redshift (z=0.81) Sunyaev-Zel'dovich (SZ) clusters discovered in the 268 deg^2 equatorial region survey of the Atacama Cosmology Telescope. For the weak lensing analysis using i'-band images, we use a model-fitting (Gauss-Laguerre shapelet) method to measure shapes of galaxy images, where we fit galaxy images in different exposures simultaneously to obtain best-fit ellipticities taking into account the different PSFs in each exposure. We also take into account the astrometric distortion effect on galaxy images by performing the model fitting in the world coordinate system. To select background galaxies behind the cluster at z=0.81, we use photometric redshift (photo-z) estimates for every galaxy derived from the co-added images of multi-passband Br'i'z'Y, with PSF matching/homogenization. After a photo-z cut for background galaxy selection, we detect the tangential weak lensing distortion signal with a total si...

  6. THE ATACAMA COSMOLOGY TELESCOPE: SUNYAEV-ZEL'DOVICH-SELECTED GALAXY CLUSTERS AT 148 GHz IN THE 2008 SURVEY

    International Nuclear Information System (INIS)

    We report on 23 clusters detected blindly as Sunyaev-ZEL'DOVICH (SZ) decrements in a 148 GHz, 455 deg2 map of the southern sky made with data from the Atacama Cosmology Telescope 2008 observing season. All SZ detections announced in this work have confirmed optical counterparts. Ten of the clusters are new discoveries. One newly discovered cluster, ACT-CL J0102-4915, with a redshift of 0.75 (photometric), has an SZ decrement comparable to the most massive systems at lower redshifts. Simulations of the cluster recovery method reproduce the sample purity measured by optical follow-up. In particular, for clusters detected with a signal-to-noise ratio greater than six, simulations are consistent with optical follow-up that demonstrated this subsample is 100% pure. The simulations further imply that the total sample is 80% complete for clusters with mass in excess of 6 x 1014 solar masses referenced to the cluster volume characterized by 500 times the critical density. The Compton y-X-ray luminosity mass comparison for the 11 best-detected clusters visually agrees with both self-similar and non-adiabatic, simulation-derived scaling laws.

  7. Young displacements on the Atacama Fault System, northern Chile from field observations and cosmogenic 21Ne concentrations

    Science.gov (United States)

    GonzáLez L., Gabriel; Dunai, Tibor; Carrizo, Daniel; Allmendinger, Richard

    2006-06-01

    We present the first numerical age constraint for young deformation of the Atacama Fault System (AFS) in northern Chile. The young activity of the AFS is expressed by several fault scarps which affects alluvial fan sediments of the eastern side of the Coastal Cordillera (23°30'-23°42'S). Detailed mapping of alluvial fans reveals a complex relationship between fault motion, erosion and alluvial fan development. An older group of alluvial fans became inactive prior to the scarp formation. Younger alluvial fans, arising directly from feeder channels and entrenched in the fault scarps, posts date the scarp formation. The youngest slip on the AFS is recorded by headward eroding channels entrenched across the scarp which are in turn displaced vertically 0.3-0.5 m by the fault. Quartz fragments in four sites on the older inactive fan group were analyzed for cosmogenic 21Ne concentrations yielding an average age of 424 ± 151 ka, the upper limit for the recent activity of the fault. Combined with the height of fault scarp, we calculate a 0.01 mm/yr minimum vertical fault slip rate. Thus young displacement on the AFS is Quaternary in age and confined to the late Pleistocene.

  8. Life in the Atacama - Year 2: Geologic Reconnaissance Through Long-Range Roving and Implications on the Search for Life

    Science.gov (United States)

    Dohm, J. M.; Cabrol, N. A.; Grin, E. A.; Moersch, J.; Diaz, G. Chong; Cockell, C.; Coppin, P.; Fisher, G.; Hock, A. N.; Ori, G. G.

    2005-01-01

    The "Life in the Atacama" (LITA) project included two field trials during the 2004 field season, each of which lasted about a week. The remote science team had no prior knowledge of the local geology, and relied entirely on orbital images and rover-acquired data to make interpretations. The sites for these trials were in different locations, and are designated "Site B" and "Site C" respectively. The primary objective of the experiment is to develop and test the means to locate, characterize, and identify habitats and life remotely through long-range roving, which included field testing the rover, named Zoe. Zoe has onboard autonomous navigation for long-range roving, a plow to overturn rocks and expose near-surface rock materials, and high-resolution imaging, spectral, and fluorescence sampling capabilities. Highlights from the experiment included characterizing the geology in and near the landing ellipse, assessing pre-mission, satellite-based hypotheses, and improving the approach and procedures used by the remote and field teams for upcoming experiments through combined satellite, field-based, and microscopic perspectives and long-range roving.

  9. The Atacama Cosmology Telescope: Dynamical masses for 44 SZ-selected galaxy clusters over 755 square degrees

    CERN Document Server

    Sifón, Cristóbal; Menanteau, Felipe; Hasselfield, Matthew; Barrientos, L Felipe; Bond, J Richard; Crichton, Devin; Devlin, Mark J; Dünner, Rolando; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Huffenberger, Kevin M; Hughes, John P; Infante, Leopoldo; Kosowsky, Arthur; Marsden, Danica; Marriage, Tobias A; Moodley, Kavilan; Niemack, Michael D; Page, Lyman A; Spergel, David N; Staggs, Suzanne T; Trac, Hy; Wollack, Edward J

    2015-01-01

    We present galaxy velocity dispersions and dynamical mass estimates for 44 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect by the Atacama Cosmology Telescope. Dynamical masses for 18 clusters are reported here for the first time. Using N-body simulations, we model the different observing strategies used to measure the velocity dispersions and account for systematic effects resulting from these strategies. We find that the galaxy velocity distributions may be treated as isotropic, and that an aperture correction of up to 7 per cent in the velocity dispersion is required if the spectroscopic galaxy sample is sufficiently concentrated towards the cluster centre. Accounting for the radial profile of the velocity dispersion in simulations enables consistent dynamical mass estimates regardless of the observing strategy. Cluster masses $M_{200}$ are in the range $(1-15)\\times10^{14}M_\\odot$. Comparing with masses estimated from the SZ distortion assuming a gas pressure profile derived from X-ray obse...

  10. Repeated mass strandings of Miocene marine mammals from Atacama Region of Chile point to sudden death at sea.

    Science.gov (United States)

    Pyenson, Nicholas D; Gutstein, Carolina S; Parham, James F; Le Roux, Jacobus P; Chavarría, Catalina Carreño; Little, Holly; Metallo, Adam; Rossi, Vincent; Valenzuela-Toro, Ana M; Velez-Juarbe, Jorge; Santelli, Cara M; Rogers, David Rubilar; Cozzuol, Mario A; Suárez, Mario E

    2014-04-22

    Marine mammal mass strandings have occurred for millions of years, but their origins defy singular explanations. Beyond human causes, mass strandings have been attributed to herding behaviour, large-scale oceanographic fronts and harmful algal blooms (HABs). Because algal toxins cause organ failure in marine mammals, HABs are the most common mass stranding agent with broad geographical and widespread taxonomic impact. Toxin-mediated mortalities in marine food webs have the potential to occur over geological timescales, but direct evidence for their antiquity has been lacking. Here, we describe an unusually dense accumulation of fossil marine vertebrates from Cerro Ballena, a Late Miocene locality in Atacama Region of Chile, preserving over 40 skeletons of rorqual whales, sperm whales, seals, aquatic sloths, walrus-whales and predatory bony fish. Marine mammal skeletons are distributed in four discrete horizons at the site, representing a recurring accumulation mechanism. Taphonomic analysis points to strong spatial focusing with a rapid death mechanism at sea, before being buried on a barrier-protected supratidal flat. In modern settings, HABs are the only known natural cause for such repeated, multispecies accumulations. This proposed agent suggests that upwelling zones elsewhere in the world should preserve fossil marine vertebrate accumulations in similar modes and densities. PMID:24573855

  11. The Atacama Cosmology Telescope: Dusty Star-Forming Galaxies and Active Galactic Nuclei in the Southern Survey

    CERN Document Server

    Marsden, Danica; Marriage, Tobias A; Switzer, Eric R; Partridge, Bruce; Massardi, Marcella; Morales, Gustavo; Addison, Graeme; Bond, J Richard; Crichton, Devin; Das, Sudeep; Devlin, Mark; Dunner, Rolando; Hajian, Amir; Hilton, Matt; Hincks, Adam; Hughes, John P; Irwin, Kent; Kosowsky, Arthur; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael; Page, Lyman; Reese, Erik D; Schmitt, Benjamin; Sehgal, Neelima; Sievers, Jonathan; Staggs, Suzanne; Swetz, Daniel; Thornton, Robert; Wollack, Edward

    2013-01-01

    We present a catalog of 191 extragalactic sources detected by the Atacama Cosmology Telescope (ACT) at 148 GHz and/or 218 GHz in the 2008 Southern survey. Flux densities span 14-1700 mJy, and we use source spectral indices derived using ACT-only data to divide our sources into two sub-populations: 167 radio galaxies powered by central active galactic nuclei (AGN), and 24 dusty star-forming galaxies (DSFGs). We cross-identify 97% of our sources (166 of the AGN and 19 of the DSFGs) with those in currently available catalogs. When combined with flux densities from the Australian Telescope 20 GHz survey and follow-up observations with the Australia Telescope Compact Array, the synchrotron-dominated population is seen to exhibit a steepening of the slope of the spectral energy distribution from 20 to 148 GHz, with the trend continuing to 218 GHz. The ACT dust-dominated source population has a median spectral index of 3.7+0.62-0.86, and includes both local galaxies and sources with redshifts as great as 5.6. Dusty ...

  12. Direct detection of precursors of gas giants formed by gravitational instability with the Atacama Large Millimetre/sub-millimetre Array

    CERN Document Server

    Mayer, Lucio; Pineda, Jaime E; Wadsley, James

    2016-01-01

    Phases of gravitational instability are expected in the early phases of disk evolution, when the disk mass is still a substantial fraction of the mass of the star. Disk fragmentation into sub-stellar objects could occur in the cold exterior part of the disk. Direct detection of massive gaseous clumps on their way to collapse into gas giant planets would offer an unprecedented test of the disk instability model. Here we use state-of-the-art 3D radiation-hydro simulations of disks undergoing fragmentation into massive gas giants, post-processed with the RADMC-3D ray-tracing code to produce dust continuum emission maps. These are then fed into the Common Astronomy Software Applications (CASA) ALMA simulator. The synthetic maps show that both overdense spiral arms and actual clumps at different stages of collapse can be detected with the Atacama Large Millimetre/sub-millimetre Array (ALMA) in the full configuration at the distance of the Ophiuchus star forming region (125 pc). The detection of clumps is particula...

  13. Detection of the pairwise kinematic Sunyaev-Zel'dovich effect with BOSS DR11 and the Atacama Cosmology Telescope

    CERN Document Server

    De Bernardis, F; Vavagiakis, E M; Niemack, M D; Battaglia, N; Beall, J; Becker, D T; Bond, J R; Calabrese, E; Cho, H; Coughlin, K; Datta, R; Devlin, M; Dunkley, J; Dunner, R; Ferraro, S; Fox, A; Gallardo, P A; Halpern, M; Hand, N; Hasselfield, M; Henderson, S W; Hill, J C; Hilton, G C; Hilton, M; Hincks, A D; Hlozek, R; Hubmayr, J; Huffenberger, K; Hughes, J P; Irwin, K D; Koopman, B J; Kosowsky, A; Li, D; Louis, T; Lungu, M; Madhavacheril, M S; Maurin, L; McMahon, J; Moodley, K; Naess, S; Nati, F; Newburgh, L; Nibarger, J P; Page, L A; Partridge, B; Schaan, E; Schmitt, B L; Sehgal, N; Sievers, J; Simon, S M; Spergel, D N; Staggs, S T; Stevens, J R; Thornton, R J; van Engelen, A; Van Lanen, J; Wollack, E J

    2016-01-01

    We present a new measurement of the kinematic Sunyaev-Zeldovich effect using data from the Atacama Cosmology Telescope (ACT) and the Baryon Oscillation Spectroscopic Survey (BOSS). Using 600 square degrees of overlapping sky area, we evaluate the mean pairwise baryon momentum associated with the positions of 50,000 bright galaxies in the BOSS DR11 Large Scale Structure catalog. A non-zero signal arises from the large-scale motions of halos containing the sample galaxies. The data fits an analytical signal model well, with the optical depth to microwave photon scattering as a free parameter determining the overall signal amplitude. We estimate the covariance matrix of the mean pairwise momentum as a function of galaxy separation, using microwave sky simulations, jackknife evaluation, and bootstrap estimates. The most conservative simulation-based errors give signal-to-noise estimates between 3.6 and 4.1 for varying galaxy luminosity cuts. We discuss how the other error determinations can lead to higher signal-...

  14. Solar Science with the Atacama Large Millimeter/Submillimeter Array—A New View of Our Sun

    Science.gov (United States)

    Wedemeyer, S.; Bastian, T.; Brajša, R.; Hudson, H.; Fleishman, G.; Loukitcheva, M.; Fleck, B.; Kontar, E. P.; De Pontieu, B.; Yagoubov, P.; Tiwari, S. K.; Soler, R.; Black, J. H.; Antolin, P.; Scullion, E.; Gunár, S.; Labrosse, N.; Ludwig, H.-G.; Benz, A. O.; White, S. M.; Hauschildt, P.; Doyle, J. G.; Nakariakov, V. M.; Ayres, T.; Heinzel, P.; Karlicky, M.; Van Doorsselaere, T.; Gary, D.; Alissandrakis, C. E.; Nindos, A.; Solanki, S. K.; Rouppe van der Voort, L.; Shimojo, M.; Kato, Y.; Zaqarashvili, T.; Perez, E.; Selhorst, C. L.; Barta, M.

    2016-04-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) is a new powerful tool for observing the Sun at high spatial, temporal, and spectral resolution. These capabilities can address a broad range of fundamental scientific questions in solar physics. The radiation observed by ALMA originates mostly from the chromosphere—a complex and dynamic region between the photosphere and corona, which plays a crucial role in the transport of energy and matter and, ultimately, the heating of the outer layers of the solar atmosphere. Based on first solar test observations, strategies for regular solar campaigns are currently being developed. State-of-the-art numerical simulations of the solar atmosphere and modeling of instrumental effects can help constrain and optimize future observing modes for ALMA. Here we present a short technical description of ALMA and an overview of past efforts and future possibilities for solar observations at submillimeter and millimeter wavelengths. In addition, selected numerical simulations and observations at other wavelengths demonstrate ALMA's scientific potential for studying the Sun for a large range of science cases.

  15. Closed bioregenerative life support systems: Applicability to hot deserts

    Science.gov (United States)

    Polyakov, Yuriy S.; Musaev, Ibrahim; Polyakov, Sergey V.

    2010-09-01

    Water scarcity in hot deserts, which cover about one-fifth of the Earth's land area, along with rapid expansion of hot deserts into arable lands is one of the key global environmental problems. As hot deserts are extreme habitats characterized by the availability of solar energy with a nearly complete absence of organic life and water, space technology achievements in designing closed ecological systems may be applicable to the design of sustainable settlements in the deserts. This review discusses the key space technology findings for closed biogenerative life support systems (CBLSS), which can simultaneously produce food, water, nutrients, fertilizers, process wastes, and revitalize air, that can be applied to hot deserts. Among them are the closed cycle of water and the acceleration of the cycling times of carbon, biogenic compounds, and nutrients by adjusting the levels of light intensity, temperature, carbon dioxide, and air velocity over plant canopies. Enhanced growth of algae and duckweed at higher levels of carbon dioxide and light intensity can be important to provide complete water recycling and augment biomass production. The production of fertilizers and nutrients can be enhanced by applying the subsurface flow wetland technology and hyper-thermophilic aerobic bacteria for treating liquid and solid wastes. The mathematical models, optimization techniques, and non-invasive measuring techniques developed for CBLSS make it possible to monitor and optimize the performance of such closed ecological systems. The results of long-duration experiments performed in BIOS-3, Biosphere 2, Laboratory Biosphere, and other ground-based closed test facilities suggest that closed water cycle can be achieved in hot-desert bioregenerative systems using the pathways of evapotranspiration, condensation, and biological wastewater treatment technologies. We suggest that the state of the art in the CBLSS design along with the possibility of using direct sunlight for

  16. Water sources for cyanobacteria below desert rocks in the Negev Desert determined by conductivity

    Directory of Open Access Journals (Sweden)

    Christopher P. McKay

    2016-04-01

    Full Text Available We present year round meteorological and conductivity measurements of colonized hypolithic rocks in the Arava Valley, Negev Desert, Israel. The data indicate that while dew is common in the Negev it is not an important source of moisture for hypolithic organisms at this site. The dominance of cyanobacteria in the hypolithic community is consistent with predictions that cyanobacteria are confined to habitats supplied by rain. To monitor the presence of liquid water under the small Negev rocks we developed and tested a simple field conductivity system based on two wires placed about 0.5 cm apart. Based on 21 replicates recorded for one year in the Negev we conclude that in natural rains (0.25 mm to 6 mm the variability between sensor readings is between 20 and 60% decreasing with increasing rain amount. We conclude that the simple small electrical conductivity system described here can be used effectively to monitor liquid water levels in lithic habitats. However, the natural variability of these sensors indicates that several replicates should be deployed. The results and method presented have use in arid desert reclamation programs.

  17. Water Sources for Cyanobacteria Below Desert Rocks in the Negev Desert Determined by Conductivity

    Science.gov (United States)

    McKay, Christopher P.

    2016-01-01

    We present year round meteorological and conductivity measurements of colonized hypolithic rocks in the Arava Valley, Negev Desert, Israel. The data indicate that while dew is common in the Negev it is not an important source of moisture for hypolithic organisms at this site. The dominance of cyanobacteria in the hypolithic community are consistent with predictions that cyanobacteria are confined to habitats supplied by rain. To monitor the presence of liquid water under the small Negev rocks we developed and tested a simple field conductivity system based on two wires placed about 0.5 cm apart. Based on 21 replicates recorded for one year in the Negev we conclude that in natural rains (0.25 mm to 6 mm) the variability between sensor readings is between 20 and 60% decreasing with increasing rain amount. We conclude that the simple small electrical conductivity system described here can be used effectively to monitor liquid water levels in lithic habitats. However, the natural variability of these sensors indicates that several replicates should be deployed. The results and method presented have use in arid desert reclamation programs.

  18. Lidar Measurements for Desert Dust Characterization: An Overview

    Directory of Open Access Journals (Sweden)

    L. Mona

    2012-01-01

    Full Text Available We provide an overview of light detection and ranging (lidar capability for describing and characterizing desert dust. This paper summarizes lidar techniques, observations, and fallouts of desert dust lidar measurements. The main objective is to provide the scientific community, including nonpractitioners of lidar observations with a reference paper on dust lidar measurements. In particular, it will fill the current gap of communication between research-oriented lidar community and potential desert dust data users, such as air quality monitoring agencies and aviation advisory centers. The current capability of the different lidar techniques for the characterization of aerosol in general and desert dust in particular is presented. Technical aspects and required assumptions of these techniques are discussed, providing readers with the pros and cons of each technique. Information about desert dust collected up to date using lidar techniques is reviewed. Lidar techniques for aerosol characterization have a maturity level appropriate for addressing air quality and transportation issues, as demonstrated by some first results reported in this paper.

  19. Snails, stable iostopes, and southwestern desert paleoclimates

    Energy Technology Data Exchange (ETDEWEB)

    Sharpe, S.E. [Univ. and Community College System of Nevada, Reno, NV (United States); Whelan, J.F.; Forester, R.M.; Burdett, J.

    1995-09-01

    Modern and fossil molluscs (snails) occur in many localities in and semi-arid regions throughout the desert southwest. Live terrestrial snails are found under rocks and in forest litter and aquatic taxa inhabit springs, seeps, and/or wetlands. Molluscs uptake local water during their growing season (spring and summer) and incorporate its delta 180 signature into their shells. Preliminary 180 analysis of modem shells from the southern Great Basin indicates that the shells probably reflect meteoric water 180 values during the growing season. This provides a way to estimate the delta 180 value of precipitation and, thereby, the source of the moisture-bearing air masses. Significant 180 variability in shells analyzed include geographic location, elevation, taxonomy, and habitat (terrestrial, spring, or wetland). We found a rough inverse correlation with elevation in modem shells from the Spring Range in southern Nevada. The delta 180 values of modem and fossil shells are also very different; modem values in this location are much higher than those from nearby late Pleistocene-age molluscs suggesting that the Pleistocene summers were variously colder and wetter than today or less evaporative (more humid). Assuming shell material directly reflects the 180 of the growing-season environment, comparison of modem and fossil shell delta 180 values can potentially identify changes in air-mass moisture sources and can help to define seasonal precipitation change through time. Comprehension and quantification of community and isotopic variability in modem gastropods is required to create probabilistic valid transfer functions with fossil materials. Valid inferences about past environmental conditions can then be established with known confidence limits.

  20. 77 FR 65133 - Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management District

    Science.gov (United States)

    2012-10-25

    ... Identification of plan. * * * * * (c) * * * (379) * * * (i) * * * (E) Mojave Desert Air Quality Management... AGENCY 40 CFR Part 52 Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management District AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: EPA...

  1. The Ocean deserts:salt budgets of northern subtropical oceans and their

    KAUST Repository

    Carton, Jim

    2011-04-09

    The Ocean deserts: salt budgets of northern subtropical oceans and their relationship to climate variability The high salinity near surface pools of the subtropical oceans are the oceanic deserts, with high levels of evaporation and low levels of precip

  2. 75 FR 53667 - Space Coast Regional Innovation Cluster Competition

    Science.gov (United States)

    2010-09-01

    ... Economic Development Administration Space Coast Regional Innovation Cluster Competition AGENCY: Economic...: This notice announces the upcoming availability of funding for the Space Coast Regional Innovation.... Additional information can be found at the Space Coast RIC Web site at...

  3. Growth responses of five desert plants as influenced by biological soil crusts from a temperate desert, China

    Science.gov (United States)

    Zhang, Yuanming; Belnap, Jayne

    2015-01-01

    In almost all dryland systems, biological soil crusts (biocrusts) coexist alongside herbaceous and woody vegetation, creating landscape mosaics of vegetated and biocrusted patches. Results from past studies on the interaction between biocrusts and vascular plants have been contradictory. In the Gurbantunggut desert, a large temperate desert in northwestern China, well-developed lichen-dominated crusts dominate the areas at the base and between the sand dunes. We examined the influence of these lichen-dominated biocrusts on the germination, growth, biomass accumulation, and elemental content of five common plants in this desert: two shrubs (Haloxylon persicum, Ephedra distachya) and three herbaceous plants (Ceratocarpus arenarius, Malcolmia africana and Lappula semiglabra) under greenhouse conditions. The influence of biocrusts on seed germination was species-specific. Biocrusts did not affect percent germination in plants with smooth seeds, but inhibited germination of seeds with appendages that reduced or eliminated contact with the soil surface or prevented seeds from slipping into soil cracks. Once seeds had germinated, biocrusts had different influences on growth of shrub and herbaceous plants. The presence of biocrusts increased concentrations of nitrogen but did not affect phosphorus or potassium in tissue of all tested species, while the uptake of the other tested nutrients was species-specific. Our study showed that biocrusts can serve as a biological filter during seed germination and also can influence growth and elemental uptake. Therefore, they may be an important trigger for determining desert plant diversity and community composition in deserts.

  4. Mycoplasma testudineum in free-ranging desert tortoises, Gopherus agassizii

    Science.gov (United States)

    Jacobson, Elliott R.; Berry, Kristin H.

    2012-01-01

    We performed clinico-pathological evaluations of 11 wild Agassiz's desert tortoises (Gopherus agassizii) from a translocation project in the central Mojave Desert, California, USA. Group 1 consisted of nine tortoises that were selected primarily due to serologic status, indicating exposure to Mycoplasma testudineum (seven) or both M. agassizii and M. testudineum (two), and secondarily due to clinical signs of upper respiratory tract disease (URTD). Group 2 consisted of two tortoises that were antibody-negative for Mycoplasma and had no clinical signs of URTD, but did have other signs of illness. Of the Group 1 tortoises, M. testudineum, but not M. agassizii, was amplified by polymerase chain reaction and DNA fingerprinted from two tortoises. Using light microscopy, mild to severe pathologic changes were observed in one or more histologic sections of either one or both nasal cavities of each tortoise in Group 1. Our findings support a causal relationship between M. testudineum and URTD in desert tortoises.

  5. Advance agriculture in the desert:the Israeli case story

    Institute of Scientific and Technical Information of China (English)

    Raanan Katzir

    2015-01-01

    The Israeli Desert constitutes 60%of the country's total area. Regional annual precipitation is 100–200 mm and evapora-tion reaches 2,500 mm. Traditional desert agriculture of rain fed wheat and sheep, goat and camels grazing is common. Despite the harsh climate conditions, advance agriculture is concentrated in foci where water resources exist. Desert ag-riculture takes advantage of the winter (October–April) due to a mild climate season for growing vegetables, flowers, herbs and fruit which are mostly exported to European countries. The key factor is the sustainable management of the local natural resources. The regional research and development (R&D) system is generating adequate local knowledge and technologies. The most important key factor is developing water resources, and using irrigation saving water systems such as drip irrigation. Technologies of protected agriculture such as greenhouses and plastic tunnels are used. The unfit desert soil is substitute by sand and artificial growing media. For gaining market purposes, introduction of botanical species was implemented for various flowers and vegetable varieties, avocado, pitaya, and jojoba. Controlled drip irrigation and drainage helps to solve salinity problems. Integrated Pest Management (IPM) is used to overcome plant protection issues. Advance raising of milking cows was developed by using reduction heat stress methods. Tilapia are raised in open ponds and greenhouse ponds, and ostriches adapted to desert conditions were introduced. On the southern Judean hills where precipitation is 250 mm, through soil conservation and rain harvesting, significant afforestation is changing the desert scenery. The human factor on this process such as farmers, agricultural extension agents and research scientists is the leading factor.

  6. 76 FR 29153 - Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management District

    Science.gov (United States)

    2011-05-20

    ... taking direct final action to approve revisions to the Mojave Desert Air Quality Management District... approving with the dates that they were adopted by the Mojave Desert Air Quality Management District (MDAQMD... AGENCY 40 CFR Part 52 Revisions to the California State Implementation Plan, Mojave Desert Air...

  7. Chemical mass balance source apportionment of fine and PM10 in the Desert Southwest, USA

    Science.gov (United States)

    The Desert Southwest Coarse Particulate Matter Study was undertaken in Pinal County, Arizona, to better understand the origin and impact of sources of fine and coarse particulate matter (PM) in rural, arid regions of the U.S. southwestern desert. The desert southwest experiences ...

  8. Determination of actual evapotranspiration and transpiration in desert sand dunes (Negev Desert) using different approaches

    Institute of Scientific and Technical Information of China (English)

    Thomas Littmann; Maik Veste

    2006-01-01

    In an arid environment, especially in sandy areas where surface runoff is of no practical importance in the hydrological budget, it is rainfall, dewfall and evapotranspiration that become the most important variables. To assess actual evapotranspiration,several methods (flux-gradient, BREB, eddy correlation) were applied to data from the Nizzana experimental site in the northwestern Negev Desert. Additionally, a model specifically designed for arid environments is introduced in this paper. This zero plane model shows the most reasonable results compared with the other methods, which overestimate evapotranspiration to a large degree. It is shown that plant transpiration is the dominant process in total evapotranspiration while advective processes do not play a major role in the near-ground boundary layer, although the study area is influenced by a sea breeze. Actual transpiration of Artemisia monosperma was measured in a field experiment to validate the calculated evapotranspiration. The vegetation contributed 41% of the calculated total evapotranspiration in a single month.

  9. Recovery of compacted soils in Mojave Desert ghost towns.

    Science.gov (United States)

    Webb, R.H.; Steiger, J.W.; Wilshire, H.G.

    1986-01-01

    Residual compaction of soils was measured at seven sites in five Mojave Desert ghost towns. Soils in these Death Valley National Monument townsites were compacted by vehicles, animals, and human trampling, and the townsites had been completely abandoned and the buildings removed for 64 to 75 yr. Recovery times extrapolated using a linear recovery model ranged from 80 to 140 yr and averaged 100 yr. The recovery times were related to elevation, suggesting freeze-thaw loosening as an important factor in ameliorating soil compaction in the Mojave Desert. -from Authors

  10. Researchers Reveal Ecological Roles of Biological Soil Crusts in Desert

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ Biological soil crust is a complex organic integrity of cyanobacteria, green algae, lichens and mosses, fungi, and other bacteria. This is a common and widespread phenomenon in desert areas all over the world. Biologically,this kind of soil crust differs a lot from physical ones in terms of physical and chemical properties, and become important biological factors in vegetation succession. Despite its unassuming appearance, the crust plays a significant role in the desert ecosystem, involving the process of soil formation, stability and fertility,the prevention of soil erosion by water or wind, the increased possibility of vascular plants colonization, and the stabilization of sand dunes.

  11. Palynology in a polar desert, eastern North Greenland

    DEFF Research Database (Denmark)

    Funder, Svend Visby; Abrahamsen, Niels

    1988-01-01

    history back to c. 7,000 years calBP (6,000 years convBP) in this·extreme environment, which presents the coldest thermal regime where vascular plants can grow. The diagram shows that polar desert developed from sparse high arctic tundra at c. 4,300 years calBP (3,900 years convBP), owing...... to reduced summer heat. Also adjacent parts of high arctic Greenland, Canada and Svalbard suffered environmental decline, and polar deserts- presently restricted to a narrow fringe of land at the shores of the Arctic Ocean-were even more restricted before this time. Like other arctic vegetation types, polar...

  12. Motion on upper-plate faults during subduction zone earthquakes: Case of the Atacama Fault System, northern Chile

    Science.gov (United States)

    Loveless, J. P.; Pritchard, M. E.

    2008-12-01

    Motion on the Atacama Fault System (AFS) in northern Chile is driven by Andean subduction zone processes. We use two approaches, observational and theoretical, to evaluate how the AFS and other forearc faults responded to coseismic stress induced by one well-studied megathrust earthquake, the 1995 Mw = 8.1 Antofagasta event. We use synthetic aperture radar interferometry (InSAR) to search for small-scale coseismic and postseismic deformation on individual faults. The InSAR data are ambiguous: some images show offset consistent with coseismic faulting on the Paposo segment of the AFS and others lack such signal. The fact that we do not observe the fault-like displacement in all coseismic interferograms suggests that atmospheric contamination, not tectonic deformation, is responsible for the signal. To explore the capacity of the earthquake to trigger motion on upper plate faults, we use seven published slip maps constrained by geodetic and/or seismic data to calculate static and dynamic Coulomb stress change (CSC) on faults in the Antofagasta region. The static CSC field varies between models and depends on the distribution of coseismic interplate slip. On the basis of the CSC distribution predicted by our preferred model constrained by all available data, we suggest it was unlikely that the Antofagasta earthquake directly triggered normal motion on the AFS, and the InSAR data are consistent with this null result. Field reports of normal faulting related to the earthquake may reflect recent (but not coseismic) motion or highly localized behavior not representative of the regional coseismic stress field.

  13. Direct Detection of Precursors of Gas Giants Formed by Gravitational Instability with the Atacama Large Millimeter/submillimeter Array

    Science.gov (United States)

    Mayer, Lucio; Peters, Thomas; Pineda, Jaime E.; Wadsley, James; Rogers, Patrick

    2016-06-01

    Phases of gravitational instability are expected in the early phases of disk evolution, when the disk mass is still a substantial fraction of the mass of the star. Disk fragmentation into sub-stellar objects could occur in the cold exterior part of the disk. Direct detection of massive gaseous clumps on their way to collapse into gas giant planets would offer an unprecedented test of the disk instability model. Here we use state-of-the-art 3D radiation-hydro simulations of disks undergoing fragmentation into massive gas giants, post-processed with RADMC-3D to produce dust continuum emission maps. These are then fed into the Common Astronomy Software Applications (CASA) ALMA simulator. The synthetic maps show that both overdense spiral arms and actual clumps at different stages of collapse can be detected with the Atacama Large Millimeter/submillimeter Array (ALMA) in the full configuration at the distance of the Ophiuchus star forming region (125 pc). The detection of clumps is particularly effective at shorter wavelengths (690 GHz) combining two resolutions with multi-scale clean. Furthermore, we show that a flux-based estimate of the mass of a protoplanetary clump can be comparable to a factor of three higher than the gravitationally bound clump mass. The estimated mass depends on the assumed opacity, and on the gas temperature, which should be set using the input of radiation-hydro simulations. We conclude that ALMA has the capability to detect “smoking gun” systems that are a signpost of the disk instability model for gas giant planet formation.

  14. The Atacama Cosmology Telescope: Cosmology from Galaxy Clusters Detected via the Sunyaev-Zel'dovich Effect

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, Neelima; Trac, Hy; Acquaviva, Viviana; Ade, Peter A.R.; Aguirre, Paula; Amiri, Mandana; Appel, John W.; Barrientos, L.Felipe; Battistelli, Elia S.; Bond, J.Richard; Brown, Ben; Burger, Bryce; Chervenak, Jay; Das, Sudeep; Devlin, Mark J.; Dicker, Simon R.; Doriese, W.Bertrand; Dunkley, Joanna; Dunner, Rolando; Essinger-Hileman, Thomas; Fisher, Ryan P.

    2011-08-18

    We present constraints on cosmological parameters based on a sample of Sunyaev-Zeldovich-selected galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of 9 optically-confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 square degrees of sky surveyed during 2008 at 148GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a 4-parameter fit. Marginalizing over the values of the parameters in this fit with conservative priors gives {sigma}{sub 8} = 0.851 {+-} 0.115 and w = -1.14 {+-} 0.35 for a spatially-flat wCDM cosmological model with WMAP 7-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP 7-year constraints alone. Fixing the scaling relation between cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find {sigma}{sub 8} = 0.821 {+-} 0.044 and w = -1.05 {+-} 0.20. These results are consistent with constraints from WMAP 7 plus baryon acoustic oscillations plus type Ia supernoava which give {sigma}{sub 8} = 0.802 {+-} 0.038 and w = -0.98 {+-} 0.053. A stacking analysis of the clusters in this sample compared to clusters simulated assuming the fiducial model also shows good agreement. These results suggest that, given the sample of clusters used here, both the astrophysics of massive clusters and the cosmological parameters derived from them are broadly consistent with current models.

  15. Muddy Coast Dynamics and Resource Management

    Science.gov (United States)

    Kjerfve, Björn

    Muddy coasts are land-sea transitional environments common along low-energy shorelines around the world. They exist in climatic settings and tidal regimes ranging from microtidal to macro-tidal. Climatic warming and relative sea level rise are likely to have a greater impact on low-lying muddy coasts and deltas than most other coastal environments. This was the working hypothesis of the Scientific Committee on Oceanic Research (SCOR) Working Group 106, “Relative Sea Level and Muddy Coasts of the World,” which concluded its deliberations in the late 1990s.

  16. Late Mesozoic to Paleogene stratigraphy of the Salar de Atacama Basin, Antofagasta, Northern Chile: Implications for the tectonic evolution of the Central Andes

    Science.gov (United States)

    Mpodozis, Constantino; Arriagada, César; Basso, Matilde; Roperch, Pierrick; Cobbold, Peter; Reich, Martin

    2005-04-01

    The Salar de Atacama basin, the largest "pre-Andean" basin in Northern Chile, was formed in the early Late Cretaceous as a consequence of the tectonic closure and inversion of the Jurassic-Early Cretaceous Tarapacá back arc basin. Inversion led to uplift of the Cordillera de Domeyko (CD), a thick-skinned basement range bounded by a system of reverse faults and blind thrusts with alternating vergence along strike. The almost 6000-m-thick, upper Cretaceous to lower Paleocene sequences (Purilactis Group) infilling the Salar de Atacama basin reflects rapid local subsidence to the east of the CD. Its oldest outcropping unit (Tonel Formation) comprises more than 1000 m of continental red sandstones and evaporites, which began to accumulate as syntectonic growth strata during the initial stages of CD uplift. Tonel strata are capped by almost 3000 m of sandstones and conglomerates of western provenance, representing the sedimentary response to renewed pulses of tectonic shortening, which were deposited in alluvial fan, fluvial and eolian settings together with minor lacustrine mudstone (Purilactis Formation). These are covered by 500 m of coarse, proximal alluvial fan conglomerates (Barros Arana Formation). The top of the Purilactis Group consists of Maastrichtian-Danian alkaline lava and minor welded tuffs and red beds (Cerro Totola Formation: 70-64 Ma K/Ar) deposited during an interval of tectonic quiescence when the El Molino-Yacoraite Late Cretaceous sea covered large tracts of the nearby Altiplano-Puna domain. Limestones interbedded with the Totola volcanics indicate that this marine incursion advanced westwards to reach the eastern CD slope. CD shortening in the Late Cretaceous was accompanied by volcanism and continental sedimentation in fault bounded basins associated to strike slip along the north Chilean magmatic arc to the west of the CD domain, indicating that oblique plate convergence prevailed during the Late Cretaceous. Oblique convergence seems to have

  17. Gulf Coast Basins and Uplifts [gcstructsg

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data provide generalized outlines of major basins and uplifts in the Gulf Coast region modified after Plate 2, Principal structural features, Gulf of Mexico...

  18. Great Lakes CoastWatch Node

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — CoastWatch is a nationwide National Oceanic and Atmospheric Administration (NOAA) program within which the Great Lakes Environmental Research Laboratory (GLERL)...

  19. West Coast Rockfish Conservation Areas, 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data delineate Rockfish Conservation Areas (RCA) off the West Coast of the United States for 2015. There are three types of areas closures depicted in this...

  20. Eighteenth annual West Coast theoretical chemistry conference

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-05-01

    Abstracts are presented from the eighteenth annual west coast theoretical chemistry conference. Topics include molecular simulations; quasiclassical simulations of reactions; photodissociation reactions; molecular dynamics;interface studies; electronic structure; and semiclassical methods of reactive systems.

  1. Salt Diapirs in the Gulf Coast [gcdiapirg

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Locations and shapes of salt diapirs were modified after the New Orleans Geological Society map, Salt tectonism of the U.S. Gulf Coast Basin (compiled by J.A....

  2. West Coast Observing System (WCOS) Temperature Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The West Coast Observing System (WCOS) project provides access to temperature and currents data collected at four of the five National Marine Sanctuary sites,...

  3. Gulf Coast Vulnerability Assessment and Conservation Framework

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The proposed partnership to support a Gulf Coast Landscape Conservation Liaison will provide much needed coordination across multiple programs and partnerships to...

  4. Education by Television in the Ivory Coast.

    Science.gov (United States)

    Valerien, Jean

    1981-01-01

    The management, administration, production, and broadcasting of educational television are discussed and evaluated with respect to its use in elementary education, training of teachers, and out-of-school education in the Ivory Coast during the 1970s. (CHC)

  5. Beryllium-10 in Ivory Coast Tektites

    Science.gov (United States)

    Serefiddin, F.; Herzog, G. F.; Koeberl, C.

    2005-03-01

    10Be concentrations in Ivory Coast tektites are consistent with formation from near surface terrestrial soils. Concentrations 77% lower than in Australasian tektites reflect differences in source materials, longer decay and environmental factors.

  6. Pacific Coast Groundfish Individual Fishing Quota Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — On January 11, 2011, NOAA Fisheries implemented a new fishery management system for the West Coast Groundfish Trawl Catch Share Program as specified in the...

  7. CoastWatch Regions in HDF Format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The mapped data derived from AVHRR is divided into files for CoastWatch regions of interest. Each file contains multiple data variables stored using the HDF-4...

  8. Distribution of seagrasses along the Indian coast

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.

    Seagrass environments, from the main coast of India, Lakshadweep and Andaman Islands, were surveyed for seagrass and marine algal composition. Extensive seagrass meadows and the maximum number of species (seven genera and 12 species) occurred along...

  9. Molecular mechanisms of foliar water uptake in a desert tree.

    Science.gov (United States)

    Yan, Xia; Zhou, Maoxian; Dong, Xicun; Zou, Songbing; Xiao, Honglang; Ma, Xiao-Fei

    2015-01-01

    Water deficits severely affect growth, particularly for the plants in arid and semiarid regions of the world. In addition to precipitation, other subsidiary water, such as dew, fog, clouds and small rain showers, may also be absorbed by leaves in a process known as foliar water uptake. With the severe scarcity of water in desert regions, this process is increasingly becoming a necessity. Studies have reported on physical and physiological processes of foliar water uptake. However, the molecular mechanisms remain less understood. As major channels for water regulation and transport, aquaporins (AQPs) are involved in this process. However, due to the regulatory complexity and functional diversity of AQPs, their molecular mechanism for foliar water uptake remains unclear. In this study, Tamarix ramosissima, a tree species widely distributed in desert regions, was investigated for gene expression patterns of AQPs and for sap flow velocity. Our results suggest that the foliar water uptake of T. ramosissima occurs in natural fields at night when the humidity is over a threshold of 85 %. The diurnal gene expression pattern of AQPs suggests that most AQP gene expressions display a circadian rhythm, and this could affect both photosynthesis and transpiration. At night, the PIP2-1 gene is also upregulated with increased relative air humidity. This gene expression pattern may allow desert plants to regulate foliar water uptake to adapt to extreme drought. This study suggests a molecular basis of foliar water uptake in desert plants. PMID:26567212

  10. Analysis of "The Wonderful Desert." Technical Report No. 170.

    Science.gov (United States)

    Green, G. M.; And Others

    This report presents a text analysis of "The Wonderful Desert," a brief selection from the "Reader's Digest Skill Builder" series. (The techniques used in arriving at the analysis are presented in a Reading Center Technical Report, Number 168, "Problems and Techniques of Text Analysis.") Tables are given for a statistical lexical analysis and for…

  11. Academic Performance, School Desertion and Emotional Paradigm in University Students

    Science.gov (United States)

    Sosa, Emma Rosa Cruz; Barrientos, Laura Gática; Castro, Patricia Eugenia García; García, Jesús Hernández

    2010-01-01

    The present work aims to describe academic performance, school desertion and the emotional paradigm of the university students of the accounting school of the Benemérita Universidad Autónoma de Puebla (FCPBUAP). We have found that low academic performance is related to students' economic deficiency, which affects their concentration on their…

  12. Sand harm in taklimakan Desert highway and sand control

    Institute of Scientific and Technical Information of China (English)

    HANZhiwen; WANGTao; SUNQingwei; DONGZhibao; WANGXunming

    2003-01-01

    Reputed as a wonderful achievement of the world’s highway construction history,the Taklimakan Desert highway is nor facing serious sand drift encroachment problems due to its 447-km-long passage of sand sea consisting of crescent dunes,barchan chains,compound transverse dune ridges and complex megadunes.To solve some technical problems in the protection of the highway from sang drift encroachment,desert experts have been conducting the theoretical and applied studies on sand movement laws;causes,severities and time-space differentiation of sand drift damages;and control ways including mechanical,chemical and biological measures.In this paper the authors give an overall summry on the research contents and recent progress in the control of sand drift damages in China and hold that the theoretical researc results and practices in the prevention of sand drift encroachment on the cross-desert highway represnt a breakthrough and has an cpoch-making significance.Since the construction of protective forest along the cross-desert highway requires large amount of ground water,what will be its environmental consequence and whether it can effectively halt sand drift encroachment on the highway forever are the questions to be studied urgently.

  13. Collection Development "Southwest Gardening": The Desert Shall Bloom

    Science.gov (United States)

    Charles, John; Mosley, Shelley; Van Winkle, Sandra

    2008-01-01

    Gardening in the American Southwest (SW) is an extreme sport. Not only are gardeners challenged by geographic extremes from tropical deserts to subalpine locales, they must also deal with a wide range of climates. Winter in the mountains and higher regions means heavy snows, frozen soils, and temperatures that can dip below zero. In contrast,…

  14. Characteristics and source of black carbon aerosol over Taklimakan Desert

    Institute of Scientific and Technical Information of China (English)

    FU; S.Joshua

    2010-01-01

    Black carbon(BC) and PM10 in the center of the Taklimakan Desert were online monitored in the whole year of 2007.In addi-tion,TSP samples were also synchronously daily collected by medium-volume samplers with Whatman41 filters in the spring of 2007.BC in the dust aerosol was up to 1.14%of the total mass of PM10.A remarkable seasonal variation of BC in the aerosol was observed in the order of winter>spring>autumn>summer.The peak value of BC appeared at midnight while the lowest one in the evening each day,which was just the reverse of that in the urban area.The contribution of BC to the total mass of PM10 on non-dust storm days was~11 times of that in dust storm.Through back trajectory and principal component analysis,it was found that BC in the dust aerosol over Taklimakan Desert might be attributed to the emission from the anthropogenic activities,including domestic heating,cooking,combustion of oil and natural gas,and the medium-range transport from those oases located in the margins of the desert.The total BC aerosol from the Taklimakan Desert to be transported to the eastward downstream was estimated to be 6.3×104 ton yr-1.

  15. Learning Desert Geomorphology Virtually versus in the Field

    Science.gov (United States)

    Stumpf, Richard J., II; Douglass, John; Dorn, Ronald I.

    2008-01-01

    Statistical analyses of pre-test and post-test results, as well as qualitative insight obtained by essays, compared introductory physical geography college students who learned desert geomorphology only virtually, in the field and both ways. With the exception of establishing geographic context, the virtual field trip was statistically…

  16. AMPHIBIAN DECLINES AND ENVIRONMENTAL CHANGE IN THE EASTERN "MOJAVE DESERT"

    Science.gov (United States)

    A number of amphibian species historically inhabited sparsely distributed wetlands in the Mojave Desert, USA, habitats that have been dramatically altered or eliminated as a result of human activities. The population status and distribution of amphibians were investigated in a 20...

  17. Dynamic response of desert wetlands to abrupt climate change.

    Science.gov (United States)

    Springer, Kathleen B; Manker, Craig R; Pigati, Jeffrey S

    2015-11-24

    Desert wetlands are keystone ecosystems in arid environments and are preserved in the geologic record as groundwater discharge (GWD) deposits. GWD deposits are inherently discontinuous and stratigraphically complex, which has limited our understanding of how desert wetlands responded to past episodes of rapid climate change. Previous studies have shown that wetlands responded to climate change on glacial to interglacial timescales, but their sensitivity to short-lived climate perturbations is largely unknown. Here, we show that GWD deposits in the Las Vegas Valley (southern Nevada, United States) provide a detailed and nearly complete record of dynamic hydrologic changes during the past 35 ka (thousands of calibrated (14)C years before present), including cycles of wetland expansion and contraction that correlate tightly with climatic oscillations recorded in the Greenland ice cores. Cessation of discharge associated with rapid warming events resulted in the collapse of entire wetland systems in the Las Vegas Valley at multiple times during the late Quaternary. On average, drought-like conditions, as recorded by widespread erosion and the formation of desert soils, lasted for a few centuries. This record illustrates the vulnerability of desert wetland flora and fauna to abrupt climate change. It also shows that GWD deposits can be used to reconstruct paleohydrologic conditions at millennial to submillennial timescales and informs conservation efforts aimed at protecting these fragile ecosystems in the face of anthropogenic warming.

  18. Ecological and evolutionary physiology of desert birds : A progress report

    NARCIS (Netherlands)

    Williams, JB; Tieleman, BI

    2002-01-01

    The adaptive significance of mechanisms of energy and water conservation among species of desert rodents, which avoid temperature extremes by remaining within a burrow during the day, is well established. Conventional wisdom holds that arid-zone birds, diurnal organisms that endure the brunt of thei

  19. Desert soil collection at the JPL soil science laboratory

    Science.gov (United States)

    Blank, G. B.; Cameron, R. E.

    1969-01-01

    Collection contains desert soils and other geologic materials collected from sites in the United States and foreign countries. Soils are useful for test purposes in research related to extraterrestrial life detection, sampling, harsh environmental studies, and determining suitable areas for training astronauts for lunar exploration.

  20. Zimbabwean army deserters in South Africa: military bonding and survival

    NARCIS (Netherlands)

    G. Maringira; A. Richters; D. Gibson

    2013-01-01

    Accounts of Zimbabwe's political crisis have mostly presented soldiers in the army as defenders of President Robert Mugabe's regime without any mention of the regime's victimization of its own soldiers. To escape further victimization many of these soldiers deserted and migrated to South Africa. In

  1. Dynamic response of desert wetlands to abrupt climate change.

    Science.gov (United States)

    Springer, Kathleen B; Manker, Craig R; Pigati, Jeffrey S

    2015-11-24

    Desert wetlands are keystone ecosystems in arid environments and are preserved in the geologic record as groundwater discharge (GWD) deposits. GWD deposits are inherently discontinuous and stratigraphically complex, which has limited our understanding of how desert wetlands responded to past episodes of rapid climate change. Previous studies have shown that wetlands responded to climate change on glacial to interglacial timescales, but their sensitivity to short-lived climate perturbations is largely unknown. Here, we show that GWD deposits in the Las Vegas Valley (southern Nevada, United States) provide a detailed and nearly complete record of dynamic hydrologic changes during the past 35 ka (thousands of calibrated (14)C years before present), including cycles of wetland expansion and contraction that correlate tightly with climatic oscillations recorded in the Greenland ice cores. Cessation of discharge associated with rapid warming events resulted in the collapse of entire wetland systems in the Las Vegas Valley at multiple times during the late Quaternary. On average, drought-like conditions, as recorded by widespread erosion and the formation of desert soils, lasted for a few centuries. This record illustrates the vulnerability of desert wetland flora and fauna to abrupt climate change. It also shows that GWD deposits can be used to reconstruct paleohydrologic conditions at millennial to submillennial timescales and informs conservation efforts aimed at protecting these fragile ecosystems in the face of anthropogenic warming. PMID:26554007

  2. Potential of energy farming in the southeastern California desert

    Energy Technology Data Exchange (ETDEWEB)

    Lew, V.

    1980-04-01

    The California Energy Commission is currently analyzing the use of energy farms to provide future sources of energy for California. Energy farms can be defined as growing plants and converting them to various forms of energy. The use of marginal desert lands in southeastern California for the siting of energy farms using acacia, Eucalyptus, euphorbia, quayule, jojoba, mesquite, or tamarisk is considered. Two hypothetical scenarios using either rainfall, or rainfall and groundwater as water sources were described to determine the maximum amount of energy produced from estimated amounts of suitable land in this area. Considering both scenarios, the maximum range of energy produced is .03 to 0.4 Quads. It is recommended that (1) genetic research be continued to increase biomass yields of these and other candidate plants grown in the desert; and (2) small test plots be established at varying desert locations to collect yield growth, and survival data. Once this information is known, the identification of the best plant(s) to use for energy farming in the California desert area will be known, as well as the cost and quantity of energy produced.

  3. Erosion resistance of bionic functional surfaces inspired from desert scorpions.

    Science.gov (United States)

    Zhiwu, Han; Junqiu, Zhang; Chao, Ge; Li, Wen; Ren, Luquan

    2012-02-01

    In this paper, a bionic method is presented to improve the erosion resistance of machine components. Desert scorpion (Androctonus australis) is a typical animal living in sandy deserts, and may face erosive action of blowing sand at a high speed. Based on the idea of bionics and biologic experimental techniques, the mechanisms of the sand erosion resistance of desert scorpion were investigated. Results showed that the desert scorpions used special microtextures such as bumps and grooves to construct the functional surfaces to achieve the erosion resistance. In order to understand the erosion resistance mechanisms of such functional surfaces, the combination of computational and experimental research were carried out in this paper. The Computational Fluid Dynamics (CFD) method was applied to predict the erosion performance of the bionic functional surfaces. The result demonstrated that the microtextured surfaces exhibited better erosion resistance than the smooth surfaces. The further erosion tests indicated that the groove surfaces exhibited better erosion performance at 30° injection angle. In order to determine the effect of the groove dimensions on the erosion resistance, regression analysis of orthogonal multinomials was also performed under a certain erosion condition, and the regression equation between the erosion rate and groove distance, width, and height was established.

  4. Enhancing and restoring habitat for the desert tortoise (Gopherus agassizii)

    Science.gov (United States)

    Abella, Scott R.; Berry, Kristin H.

    2016-01-01

    Habitat has changed unfavorably during the past 150 years for the desert tortoise (Gopherus agassizii), a threatened species with declining populations in the Mojave and western Sonoran Desert. To support recovery efforts, we synthesized published information on relationships of desert tortoises with three habitat features (cover sites, forage, and soil) and candidate management practices for improving these features for tortoises. In addition to their role in soil health and facilitating recruitment of annual forage plants, shrubs are used by desert tortoises for cover and as sites for burrows. Outplanting greenhouse-grown seedlings, protected from herbivory, has successfully restored (>50% survival) a variety of shrubs on disturbed desert soils. Additionally, salvaging and re-applying topsoil using effective techniques is among the more ecologically beneficial ways to initiate plant recovery after severe disturbance. Some plant species provide better-quality forage than others. Tortoises selectively forage on particular annual and herbaceous perennial species, such as legumes, with favored plants varying with phenological stage within years. Non-native grasses are non-preferred forage and contribute fuel to spreading wildfires, which damage or kill shrubs that tortoises use for cover. Maintaining a diverse "menu" of native annual forbs and decreasing non-native grasses are priorities for restoring most desert tortoise habitats. Reducing herbivory by non-native animals, carefully timing herbicide applications, and strategically augmenting annual forage plants via seeding show promise for improving tortoise forage quality. Roads, another disturbance, negatively affect habitat in numerous ways (e.g., compacting soil, altering hydrology). Techniques such as re-contouring road berms to reestablish drainage patterns, vertical mulching ("planting" dead plant material), and creating barriers to prevent trespasses can assist natural recovery on decommissioned backcountry

  5. Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts

    Science.gov (United States)

    Darby, B.J.; Housman, D.C.; Zaki, A.M.; Shamout, Y.; Adl, S.M.; Belnap, J.; Neher, D.A.

    2006-01-01

    Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37??C. Cysts survived the upper end of daily temperatures (37-55??C), and could be stimulated to excyst if temperatures were reduced to 15??C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime. ?? 2006 by the International Society of Protistologists.

  6. Biological soil crusts as an integral component of desert environments

    Science.gov (United States)

    Belnap, Jayne; Weber, Bettina

    2013-01-01

    The biology and ecology of biological soil crusts, a soil surface community of mosses, lichens, cyanobacteria, green algae, fungi, and bacteria, have only recently been a topic of research. Most efforts began in the western U.S. (Cameron, Harper, Rushforth, and St. Clair), Australia (Rogers), and Israel (Friedmann, Evenari, and Lange) in the late 1960s and 1970s (e.g., Friedmann et al. 1967; Evenari 1985reviewed in Harper and Marble 1988). However, these groups worked independently of each other and, in fact, were often not aware of each other’s work. In addition, biological soil crust communities were seen as more a novelty than a critical component of dryland ecosystems. Since then, researchers have investigated many different aspects of these communities and have shown that although small to microscopic, biological soil crusts are critical in many ecological processes of deserts. They often cover most of desert soil surfaces and substantially mediate inputs and outputs from desert soils (Belnap et al. 2003). They can be a large source of biodiversity for deserts, as they can contain more species than the surrounding vascular plant community (Rosentreter 1986). These communities are important in reducing soil erosion and increasing soil fertility through the capture of dust and the fixation of atmospheric nitrogen and carbon into forms available to other life forms (Elbert et al. 2012). Because of their many effects on soil characteristics, such as external and internal morphological characteristics, aggregate stability, soil moisture, and permeability, they also affect seed germination and establishment and local hydrological cycles. Covering up to 70% of the surface area in many arid and semi-arid regions around the world (Belnap and Lange 2003), biological soil crusts are a key component within desert environments.

  7. Diversity and Ecology of Viruses in Hyperarid Desert Soils.

    Science.gov (United States)

    Zablocki, Olivier; Adriaenssens, Evelien M; Cowan, Don

    2016-02-01

    In recent years, remarkable progress has been made in the field of virus environmental ecology. In marine ecosystems, for example, viruses are now thought to play pivotal roles in the biogeochemical cycling of nutrients and to be mediators of microbial evolution through horizontal gene transfer. The diversity and ecology of viruses in soils are poorly understood, but evidence supports the view that the diversity and ecology of viruses in soils differ substantially from those in aquatic systems. Desert biomes cover ∼ 33% of global land masses, and yet the diversity and roles of viruses in these dominant ecosystems remain poorly understood. There is evidence that hot hyperarid desert soils are characterized by high levels of bacterial lysogens and low extracellular virus counts. In contrast, cold desert soils contain high extracellular virus titers. We suggest that the prevalence of microbial biofilms in hyperarid soils, combined with extreme thermal regimens, exerts strong selection pressures on both temperate and virulent viruses. Many desert soil virus sequences show low values of identity to virus genomes in public databases, suggesting the existence of distinct and as-yet-uncharacterized soil phylogenetic lineages (e.g., cyanophages). We strongly advocate for amplification-free metavirome analyses while encouraging the classical isolation of phages from dominant and culturable microbial isolates in order to populate sequence databases. This review provides an overview of recent advances in the study of viruses in hyperarid soils and of the factors that contribute to viral abundance and diversity in hot and cold deserts and offers technical recommendations for future studies. PMID:26590289

  8. Diversity and Ecology of Viruses in Hyperarid Desert Soils

    Science.gov (United States)

    Zablocki, Olivier; Adriaenssens, Evelien M.

    2015-01-01

    In recent years, remarkable progress has been made in the field of virus environmental ecology. In marine ecosystems, for example, viruses are now thought to play pivotal roles in the biogeochemical cycling of nutrients and to be mediators of microbial evolution through horizontal gene transfer. The diversity and ecology of viruses in soils are poorly understood, but evidence supports the view that the diversity and ecology of viruses in soils differ substantially from those in aquatic systems. Desert biomes cover ∼33% of global land masses, and yet the diversity and roles of viruses in these dominant ecosystems remain poorly understood. There is evidence that hot hyperarid desert soils are characterized by high levels of bacterial lysogens and low extracellular virus counts. In contrast, cold desert soils contain high extracellular virus titers. We suggest that the prevalence of microbial biofilms in hyperarid soils, combined with extreme thermal regimens, exerts strong selection pressures on both temperate and virulent viruses. Many desert soil virus sequences show low values of identity to virus genomes in public databases, suggesting the existence of distinct and as-yet-uncharacterized soil phylogenetic lineages (e.g., cyanophages). We strongly advocate for amplification-free metavirome analyses while encouraging the classical isolation of phages from dominant and culturable microbial isolates in order to populate sequence databases. This review provides an overview of recent advances in the study of viruses in hyperarid soils and of the factors that contribute to viral abundance and diversity in hot and cold deserts and offers technical recommendations for future studies. PMID:26590289

  9. Elemental profiles and signatures of fugitive dusts from Chinese deserts.

    Science.gov (United States)

    Zhang, Rong; Cao, Junji; Tang, Yanrong; Arimoto, Richard; Shen, Zhenxing; Wu, Feng; Han, Yongming; Wang, Gehui; Zhang, Jiaquan; Li, Guohui

    2014-02-15

    Elemental profiles were determined for size-separated fugitive dust particles produced from Chinese desert and gobi soils. Seventeen surface soil samples from six Chinese deserts were collected, composited, resuspended, and sampled through TSP, PM10, and PM2.5 inlets onto Teflon® filters, which were analyzed for twenty-six elements. Two major dust sources could be distinguished based on differences in crustal and enriched elements-the northwestern (NW) region (Taklimakan Desert, Xinjiang Gobi, and Anxinan Gobi) and northern (N) region (Ulan Buh Desert, Central Inner Mongolia Desert, and Erenhot Gobi). The N sources showed lower concentrations of mineral elements (Fe, K, Na, Ti, Mn, Cr, and Rb in PM10, and Fe, K, Ti, Mn, Co, and V in PM2.5) and higher levels of contaminants (S, Zn, Mo, Cu, Cr, Pb, Cd, and As) than the NW ones, especially in PM2.5. Enrichment factors for Cu, Cr, Zn, Pb, As, Mo, and Cd calculated relative to the upper continental crust showed enrichments of one to two orders-of-magnitude, and they were much higher for N sources than NW ones, implying stronger anthropogenic impacts in north China. Aerosol elemental concentrations during dust events at Horqin, Beijing, and Xi'an matched the mass percentages of mineral elements from their presumptive sources better than the alternative ones, validating the differences between the NW and N sources. Additionally, Na/S, Mg/S, Fe/Al, K/Al, Si/Fe, and Na/Al ratios were suggested to differentiate the two dust source regions. The elemental ratios of Ca/Al, K/Al, Fe/Al, and Ti/Fe in the source regions matched those in aerosols collected downwind, and they can be considered as possible source indicators. PMID:24361747

  10. Geological development and mineralization in the Atacama segment of the South American Andes, northern Chile (26°15' 27°25'S)

    Science.gov (United States)

    Palacios, Carlos M.; Townley, Brian C.; Lahsen, Alfredo A.; Egaña, Antonio M.

    1993-12-01

    Between the Late Jurassic and the Middle Miocene, widespread magmatism, tectonic events and hydrothermal mineralization characterized the geological evolution of the Atacama segment of the South American Andes. A characteristic feature of this zone is the coincidence in time and space between subduction-generated igneous activity, crustal deformation and mineralization in the magmatic arcs, which formed longitudinal belts migrating eastward. Mineralization in the last 140 Ma is generally restricted to four longitudinal metallogenic belts, in which hydrothermal activity was channelled along crustal-scale faults (1) the Atacama Fault System, along which Early Cretaceous Cu-Au-bearing breccia pipes, veins and stockwork were formed; (2) the Inca do Oro Belt, which contains Upper Cretaceous low sulphur precious metal epithermal mineralization, and Middle Eocene Cu-Mo-Au-bearing breccia pipes; (3) the West Fissure System, which hosts Upper Eocene to Early Oligocene porphyry copper deposits and high sulphur precious metal epithermal mineralization; and (4) the Maricunga Belt, when contains Upper Oligocene to Middle Miocene high sulphur precious metal epithermal deposits and Au-rich porphyry mineralization.

  11. Effects of subsidized predators, resource variability, and human population density on desert tortoise populations in the Mojave Desert, USA

    Science.gov (United States)

    Esque, Todd C.; Nussear, Kenneth E.; Drake, K. Kristina; Walde, Andrew D.; Berry, Kristin H.; Averill-Murray, Roy C.; Woodman, A. Peter; Boarman, William I.; Medica, Phil A.; Mack, Jeremy S.; Heaton, Jill S.

    2010-01-01

    Understanding predator–prey relationships can be pivotal in the conservation of species. For 2 decades, desert tortoise Gopherus agassizii populations have declined, yet quantitative evidence regarding the causes of declines is scarce. In 2005, Ft. Irwin National Training Center, California, USA, implemented a translocation project including 2 yr of baseline monitoring of desert tortoises. Unusually high predation on tortoises was observed after translocation occurred. We conducted a retrospective analysis of predation and found that translocation did not affect the probability of predation: translocated, resident, and control tortoises all had similar levels of predation. However, predation rates were higher near human population concentrations, at lower elevation sites, and for smaller tortoises and females. Furthermore, high mortality rates were not limited to the National Training Center. In 2008, elevated mortality (as high as 43%) occurred throughout the listed range of the desert tortoise. Although no temporal prey base data are available for analysis from any of the study sites, we hypothesize that low population levels of typical coyote Canis latrans prey (i.e. jackrabbits Lepus californicus and other small animals) due to drought conditions influenced high predation rates in previous years. Predation may have been exacerbated in areas with high levels of subsidized predators. Many historical reports of increased predation, and our observation of a range-wide pattern, may indicate that high predation rates are more common than generally considered and may impact recovery of the desert tortoise throughout its range.

  12. FutureCoast: "Listen to your futures"

    Science.gov (United States)

    Pfirman, S. L.; Eklund, K.; Thacher, S.; Orlove, B. S.; Diane Stovall-Soto, G.; Brunacini, J.; Hernandez, T.

    2014-12-01

    Two science-arts approaches are emerging as effective means to convey "futurethinking" to learners: systems gaming and experiential futures. FutureCoast exemplifies the latter: by engaging participants with voicemails supposedly leaking from the cloud of possible futures, the storymaking game frames the complexities of climate science in relatable contexts. Because participants make the voicemails themselves, FutureCoast opens up creative ways for people to think about possibly climate-changed futures and personal ways to talk about them. FutureCoast is a project of the PoLAR Partnership with a target audience of informal adult learners primarily reached via mobile devices and online platforms. Scientists increasingly use scenarios and storylines as ways to explore the implications of environmental change and societal choices. Stories help people make connections across experiences and disciplines and link large-scale events to personal consequences. By making the future seem real today, FutureCoast's framework helps people visualize and plan for future climate changes. The voicemails contributed to FutureCoast are spread through the game's intended timeframe (2020 through 2065). Based on initial content analysis of voicemail text, common themes include ecosystems and landscapes, weather, technology, societal issues, governance and policy. Other issues somewhat less frequently discussed include security, food, industry and business, health, energy, infrastructure, water, economy, and migration. Further voicemail analysis is examining: temporal dimensions (salient time frames, short vs. long term issues, intergenerational, etc.), content (adaptation vs. mitigation, challenges vs. opportunities, etc.), and emotion (hopeful, resigned, etc. and overall emotional context). FutureCoast also engaged audiences through facilitated in-person experiences, geocaching events, and social media (Tumblr, Twitter, Facebook, YouTube). Analysis of the project suggests story

  13. Upper crustal fault reactivation and the potential of triggered earthquakes on the Atacama Fault System, N-Chile

    Science.gov (United States)

    Victor, Pia; Ewiak, Oktawian; Thomas, Ziegenhagen; Monika, Sobiesiak; Bernd, Schurr; Gabriel, Gonzalez; Onno, Oncken

    2016-04-01

    The Atacama Fault System (AFS) is an active trench-parallel fault system, located in the forearc of N-Chile directly above the subduction zone interface. Due to its well-exposed position in the hyper arid forearc of N-Chile it is the perfect target to investigate the interaction between the deformation cycle in the overriding forearc and the subduction zone seismic cycle of the underlying megathrust. Although the AFS and large parts of the upper crust are devoid of any noteworthy seismicity, at least three M=7 earthquakes in the past 10 ky have been documented in the paleoseismological record, demonstrating the potential of large events in the future. We apply a two-fold approach to explore fault activation and reactivation patterns through time and to investigate the triggering potential of upper crustal faults. 1) A new methodology using high-resolution topographic data allows us to investigate the number of past earthquakes for any given segment of the fault system as well as the amount of vertical displacement of the last increment. This provides us with a detailed dataset of past earthquake rupture of upper plate faults which is potentially linked to large subduction zone earthquakes. 2) The IPOC Creepmeter array (http://www.ipoc-network.org/index.php/observatory/creepmeter.html) provides us with high-resolution time series of fault displacement accumulation for 11 stations along the 4 most active branches of the AFS. This array monitors the displacement across the fault with 2 samples/min with a resolution of 1μm. Collocated seismometers record the seismicity at two of the creepmeters, whereas the regional seismicity is provided by the IPOC Seismological Networks. Continuous time series of the creepmeter stations since 2009 show that the shallow segments of the fault do not creep permanently. Instead the accumulation of permanent deformation occurs by triggered slip caused by local or remote earthquakes. The 2014 Mw=8.2 Pisagua Earthquake, located close to

  14. Development of a self-similar strike-slip duplex system in the Atacama Fault system, Chile

    Science.gov (United States)

    Jensen, E.; Cembrano, J.; Faulkner, D.; Veloso, E.; Arancibia, G.

    2011-11-01

    Fault development models are crucial to predict geometry and distribution of fractures at all scales. We present here structures related to the development of the Bolfín Fault in the Atacama Fault System (AFS), covering a range of scales of 7 orders of magnitude. The AFS is a 1000 km-long trench-parallel fault system located in the Andean Forearc. The Bolfín Fault is a first-order fault of the Caleta Coloso Duplex, has a trend ∼170° and length >45 km. It cuts mainly meta-diorites and exhibits a 100-200 m thick core of subvertical bands of altered fractured host rock and of foliated cataclasites. This foliation is made up of several trend-parallel cm-thick shear bands, composed of plagioclase fragments (>0.1 mm) surrounded by epidote. In the compressive quadrant around the tip point of Bolfín Fault, the lower strain faults exhibit an unusual internal structure consisting of fractures arranged in a multi-duplex pattern. This pattern can be observed from meters to millimeters scale. The fractures in the strike-slip duplex pattern can be separated into two types. Main Faults: trend-parallel, longer and with larger offsets; and Secondary Fractures: sigmoid-shape fractures distributed in the regions between Main Faults, all oriented between 15° and 75° with respect to the Main Faults, measured counterclockwise (i.e. in P-diedra). On the basis of the distribution of the two types of recognized fractures, the relative sequence of propagation can be inferred. Main Faults, the more widely distributed, propagated earlier. The Secondary Fractures, in turn, distributed in thinner areas between the larger Main Faults, were propagated later as linking fractures. The duplex pattern is self-similar: Multiple-Core Faults with internal structure of multiple-duplex are itself in turn secondary faults within a larger km-scale duplex (Caleta Coloso Duplex). The duplex width (W) and the length (L) of the Main Faults forming the duplex show an almost linear relationship, for

  15. Extensional Basins in a Convergent Margin: Oligocene-Early Miocene Salar de Atacama and Calama basins, Central Andes

    Science.gov (United States)

    Jordan, T. E.; Mpodozis, C.; Blanco, N.; Pananont, P.; Dávila, F.

    2004-12-01

    The Salar de Atacama Basin (SdAB) is the largest and most persistent sedimentary basin of northern Chile, accumulating nonmarine sediment from Cretaceous to modern times. Its northwestern neighbor, the Calama, was a Cenozoic basin. Although SdAB was in the backarc zone early in the Andean orogeny, both are now forearc basins. Others demonstrated that the basins overlie anomalously cold, strong, and dense crust and lithosphere. We focus on an extensional Oligocene basin stage. Interpretation of the basin-controlling faults is based on seismic reflection studies supported by field relations. The SdAB is limited to the west by the NNE-trending, steeply east-dipping, Paciencia Fault (PF). The PF experienced 5-7 km of down-to-the-east offset during the Oligocene-early Miocene. Syntectonic strata, an arid succession of siliciclastics and evaporites, are asymmetric, with thicknesses of 5000 m and abundant halite adjacent to the PF, and of 1000 m with fine detrital clastic strata 25 km farther east. Relations in conglomeratic growth strata that overlap the PF also demonstrate normal displacement during sediment accumulation. Seismic data reveal that a buried normal fault with 1-1.5 km down-to-the-east displacement limits the western margin of the Oligocene-Miocene Calama siliciclastic basin fill. Regionally, Oligocene-early Miocene margin-parallel strike-slip deformation dominated northwest of the basins, contributing sinistral offset (West Fissure Fault) to the northern segment of the long-lived Domeyko Fault System. The new SdAB and Calama data reveal that a 20,000 km2 domain of extensional basins existed within the dominantly strike-slip region. Even if PF and the fault in the Calama Basin were transtensional, the proportion of extension to strike-slip displacement is much greater in these basins than elsewhere in northern Chile. Further study is required to understand what combination of factors caused this kinematic distinction as well as delayed the onset of CVZ

  16. THE ATACAMA COSMOLOGY TELESCOPE: PHYSICAL PROPERTIES OF SUNYAEV-ZEL'DOVICH EFFECT CLUSTERS ON THE CELESTIAL EQUATOR {sup ,}

    Energy Technology Data Exchange (ETDEWEB)

    Menanteau, Felipe; Hughes, John P. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Sifon, Cristobal; Barrientos, L. Felipe; Duenner, Rolando; Infante, Leopoldo [Departamento de Astronomia y Astrofisica, Facultad de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Battaglia, Nicholas [McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Bond, J. Richard; Hajian, Amir; Hincks, Adam D. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Crichton, Devin; Gralla, Megan; Marriage, Tobias A. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218-2686 (United States); Das, Sudeep [High Energy Physics Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, IL 60439 (United States); Devlin, Mark J.; Dicker, Simon [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Hasselfield, Matthew [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Hilton, Matt [Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Durban (South Africa); Kosowsky, Arthur [Physics and Astronomy Department, University of Pittsburgh, 100 Allen Hall, 3941 O' Hara Street, Pittsburgh, PA 15260 (United States); Marsden, Danica [Department of Physics, University of California Santa Barbara, CA 93106 (United States); and others

    2013-03-01

    We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 deg{sup 2} centered on the celestial equator, is divided into two regions. The main region uses 270 deg{sup 2} of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed observations with the Apache Point Observatory 3.5 m telescope. We confirm a total of 49 clusters to z Almost-Equal-To 1.3, of which 22 (all at z > 0.55) are new discoveries. For the second region, the regular-depth SDSS imaging allows us to confirm 19 more clusters up to z Almost-Equal-To 0.7, of which 10 systems are new. We present the optical richness, photometric redshifts, and separation between the SZ position and the brightest cluster galaxy (BCG). We find no significant offset between the cluster SZ centroid and BCG location and a weak correlation between optical richness and SZ-derived mass. We also present X-ray fluxes and luminosities from the ROSAT All Sky Survey which confirm that this is a massive sample. One of the newly discovered clusters, ACT-CL J0044.4+0113 at z = 1.1 (photometric), has an integrated XMM-Newton X-ray temperature of kT{sub X} = 7.9 {+-} 1.0 keV and combined mass of M {sub 200a} = 8.2{sup +3.3} {sub -2.5} Multiplication-Sign 10{sup 14} h {sup -1} {sub 70} M {sub Sun }, placing it among the most massive and X-ray-hot clusters known at redshifts beyond z = 1. We also highlight the optically rich cluster ACT-CL J2327.4-0204 (RCS2 2327) at z = 0.705 (spectroscopic) as the most significant detection of the whole equatorial sample with a Chandra-derived mass of M {sub 200a} = 1.9{sup +0.6} {sub -0.4} Multiplication-Sign 10{sup 15} h {sup -1} {sub 70} M {sub Sun }, placing it in the ranks of the most massive known clusters like El Gordo and the Bullet Cluster.

  17. Urban Heat Island Variation across a Dramatic Coastal to Desert Climate Zone: An Application to Los Angeles, CA Metropolitan Area

    Science.gov (United States)

    Tayyebi, A.; Jenerette, D.

    2015-12-01

    Urbanization is occurring at an unprecedented rate across the globe. The resulting urban heat island (UHI), which is a well-known phenomenon in urban areas due to the increasing number and density of buildings, leads to higher temperature in urban areas than surrounding sub-urban or rural areas. Understanding the effects of landscape pattern on UHI is crucial for improving the sustainability of cities and reducing heat vulnerability. Although a variety of studies have quantified UHI, there are a lack of studies to 1) understand UHI variation at the micro-scale (e.g., neighborhood effect) for large urban areas and 2) identify variation in the sensitivity of the UHI to environmental drivers across a megacity with a pronounced climate zone (i.e. coastal to desert climates) using advanced analytical tools. In this study, we identified the interacting relationship among various environmental and socio-economic factors to better identify UHI over the Los Angeles, CA metropolitan area. We used structural equation modeling (SEM) to quantify the interacting relationships among land surface temperature (LST), land cover (NDVI), distance to ocean, elevation, and socio-economic status (neighborhood income). LST-NDVI slopes were negative across the climate zones and became progressively stronger with increasing distance from the coast. Results also showed that slopes between NDVI and neighborhood income were positive throughout the climate zone with a maximum in the relationship occurring near 25km from the coast. Because of these income-NDVI and NDVI-LST relationships we also found that slopes between LST and neighborhood income were negative throughout the climate zones and peaked at about 30km from the coast. These findings suggest assessments of urban heat vulnerability need to consider not only variation in the indicators but also variation in how the indicators influence vulnerability.

  18. Inversion of the asymmetry factor for desert areas of China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Deserts,which have high surface albedo and wide area,are important components of the earth system.It is very important for the research of surface radiation and energy balance to understand the anisotropic scattering of desert areas.The emergence and development of multi-angle remote sensing made possible the inversion of the anisotropic scattering of desert areas at the regional or global scale.Firstly,this paper explored the accuracy of the inversion of asymmetry factor using the Hapke model and the simulated single-and multi-phase MISR data.Based on the results,the asymmetry factor of representative surface of desert areas in northwestern China was retrieved.The values of the asymmetry factor retrieved from MISR data were compared with the values retrieved from the laboratory data.The results showed that the single-phase MISR data could be used for the inversion of asymmetry parameter of desert areas.The sign of the asymmetry parameter for the laboratory measurements was positive,which suggests that the surface of laboratory samples is forward scattering.The sign of the asymmetry parameter for MISR data was negative;that is,it is backscattering.The values of the asymmetry parameters retrieved from MISR data were related to the character of the land surface.At Loulan,where the surface was smoother than other sites,retrieved values exhibited the largest negative values of asymmetry factor,suggesting the strongest backscattering.The sand dune area of the Kumtag Desert,which has the greatest roughness,had only slightly negative asymmetry factor values.These findings indicated that at the sensor scale,a rough surface(e.g.,dunes) does not necessarily mean more backscattering than a smooth surface.This finding has significant implications for empirical methods(e.g.,using the normalized index of backward-scattered radiance minus forward-scattered radiance as an indicator of surface roughness),which should be used carefully for analyzing surface roughness from the remote

  19. Dramatic Demand Reduction In The Desert Southwest

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert [Univ. of Nevada, Las Vegas, NV (United States); Hsieh, Sean [Univ. of Nevada, Las Vegas, NV (United States); Lee, Joon [Univ. of Nevada, Las Vegas, NV (United States); Baghzouz, Yahia [Univ. of Nevada, Las Vegas, NV (United States); Cross, Andrew [Univ. of Nevada, Las Vegas, NV (United States); Chatterjee, Sarah [NV Energy, Las Vegas, NV (United States)

    2015-07-06

    This report summarizes a project that was funded to the University of Nevada Las Vegas (UNLV), with subcontractors Pulte Homes and NV Energy. The project was motivated by the fact that locations in the Desert Southwest portion of the US demonstrate very high peak electrical demands, typically in the late afternoons in the summer. These high demands often require high priced power to supply the needs, and the large loads can cause grid supply problems. An approach was proposed through this contact that would reduce the peak electrical demands to an anticipated 65% of what code-built houses of the similar size would have. It was proposed to achieve energy reduction through four approaches applied to a development of 185 homes in northwest part of Las Vegas named Villa Trieste. First, the homes would all be highly energy efficient. Secondly, each house would have a PV array installed on it. Third, an advanced demand response technique would be developed to allow the resident to have some control over the energy used. Finally, some type of battery storage would be used in the project. Pulte Homes designed the houses. The company considered initial cost vs. long-term savings and chose options that had relatively short paybacks. HERS (Home Energy Rating Service) ratings for the homes are approximately 43 on this scale. On this scale, code-built homes rate at 100, zero energy homes rate a 0, and Energy Star homes are 85. In addition a 1.764 Wp (peak Watt) rated PV array was used on each house. This was made up of solar shakes that were in visual harmony with the roofing material used. A demand response tool was developed to control the amount of electricity used during times of peak demand. While demand response techniques have been used in the utility industry for some time, this particular approach is designed to allow the customer to decide the degree of participation in the response activity. The temperature change in the residence can be decided by the residents by

  20. Dramatic Demand Reduction In The Desert Southwest

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert [Univ. of Nevada, Las Vegas, NV (United States); Hsieh, Sean [Univ. of Nevada, Las Vegas, NV (United States); Lee, Joon [Univ. of Nevada, Las Vegas, NV (United States); Baghzouz, Yahia [Univ. of Nevada, Las Vegas, NV (United States); Cross, Andrew [Univ. of Nevada, Las Vegas, NV (United States); Chatterjee, Sarah [NV Energy, Las Vegas, NV (United States)

    2015-07-06

    This report summarizes a project that was funded to the University of Nevada Las Vegas (UNLV), with subcontractors Pulte Homes and NV Energy. The project was motivated by the fact that locations in the Desert Southwest portion of the US demonstrate very high peak electrical demands, typically in the late afternoons in the summer. These high demands often require high priced power to supply the needs, and the large loads can cause grid supply problems. An approach was proposed through this contact that would reduce the peak electrical demands to an anticipated 65% of what code-built houses of the similar size would have. It was proposed to achieve energy reduction through four approaches applied to a development of 185 homes in northwest part of Las Vegas named Villa Trieste. First, the homes would all be highly energy efficient. Secondly, each house would have a PV array installed on it. Third, an advanced demand response technique would be developed to allow the resident to have some control over the energy used. Finally, some type of battery storage would be used in the project. Pulte Homes designed the houses. The company considered initial cost vs. long-term savings and chose options that had relatively short paybacks. HERS (Home Energy Rating Service) ratings for the homes are approximately 43 on this scale. On this scale, code-built homes rate at 100, zero energy homes rate a 0, and Energy Star homes are 85. In addition a 1.764 Wp (peak Watt) rated PV array was used on each house. This was made up of solar shakes that were in visual harmony with the roofing material used. A demand response tool was developed to control the amount of electricity used during times of peak demand. While demand response techniques have been used in the utility industry for some time, this particular approach is designed to allow the customer to decide the degree of participation in the response activity. The temperature change in the residence can be decided by the residents by

  1. Prolactin stress response does not predict brood desertion in a polyandrous shorebird.

    Science.gov (United States)

    Kosztolányi, András; Küpper, Clemens; Chastel, Olivier; Parenteau, Charline; Yılmaz, K Tuluhan; Miklósi, Adám; Székely, Tamás; Lendvai, Adám Z

    2012-05-01

    One of the fundamental principles of the life-history theory is that parents need to balance their resources between current and future offspring. Deserting the dependent young is a radical life-history decision that saves resources for future reproduction but that may cause the current brood to fail. Despite the importance of desertion for reproductive success, and thus fitness, the neuroendocrine mechanisms of brood desertion are largely unknown. We investigated two candidate hormones that may influence brood desertion in the Kentish plover Charadrius alexandrinus: prolactin ('parental hormone') and corticosterone ('stress hormone'). Kentish plovers exhibit an unusually diverse mating and parental care system: brood desertion occurs naturally since either parent (the male or the female) may desert the brood after the chicks hatch and mate with a new partner shortly after. We measured the hormone levels of parents at hatching using the standard capture and restraint protocol. We subsequently followed the broods to determine whether a parent deserted the chicks. We found no evidence that either baseline or stress-induced prolactin levels of male or female parents predicted brood desertion. Although stress-induced corticosterone levels were generally higher in females compared with males, individual corticosterone levels did not explain the probability of brood desertion. We suggest that, in this species, low prolactin levels do not trigger brood desertion. In general, we propose that the prolactin stress response does not reflect overall parental investment in a species where different parts of the breeding cycle are characterized by contrasting individual investment strategies. PMID:22504343

  2. Prolactin stress response does not predict brood desertion in a polyandrous shorebird.

    Science.gov (United States)

    Kosztolányi, András; Küpper, Clemens; Chastel, Olivier; Parenteau, Charline; Yılmaz, K Tuluhan; Miklósi, Adám; Székely, Tamás; Lendvai, Adám Z

    2012-05-01

    One of the fundamental principles of the life-history theory is that parents need to balance their resources between current and future offspring. Deserting the dependent young is a radical life-history decision that saves resources for future reproduction but that may cause the current brood to fail. Despite the importance of desertion for reproductive success, and thus fitness, the neuroendocrine mechanisms of brood desertion are largely unknown. We investigated two candidate hormones that may influence brood desertion in the Kentish plover Charadrius alexandrinus: prolactin ('parental hormone') and corticosterone ('stress hormone'). Kentish plovers exhibit an unusually diverse mating and parental care system: brood desertion occurs naturally since either parent (the male or the female) may desert the brood after the chicks hatch and mate with a new partner shortly after. We measured the hormone levels of parents at hatching using the standard capture and restraint protocol. We subsequently followed the broods to determine whether a parent deserted the chicks. We found no evidence that either baseline or stress-induced prolactin levels of male or female parents predicted brood desertion. Although stress-induced corticosterone levels were generally higher in females compared with males, individual corticosterone levels did not explain the probability of brood desertion. We suggest that, in this species, low prolactin levels do not trigger brood desertion. In general, we propose that the prolactin stress response does not reflect overall parental investment in a species where different parts of the breeding cycle are characterized by contrasting individual investment strategies.

  3. Mineral compositions and sources of the riverbed sediment in the desert channel of Yellow River.

    Science.gov (United States)

    Jia, Xiaopeng; Wang, Haibing

    2011-02-01

    The Yellow River flows through an extensive, aeolian desert area and extends from Xiaheyan, Ningxia Province, to Toudaoguai, Inner Mongolia Province, with a total length of 1,000 km. Due to the construction and operation of large reservoirs in the upstream of the Yellow River, most water and sediment from upstream were stored in these reservoirs, which leads to the declining flow in the desert channel that has no capability to scour large amount of input of desert sands from the desert regions. By analyzing and comparing the spatial distribution of weight percent of mineral compositions between sediment sources and riverbed sediment of the main tributaries and the desert channel of the Yellow River, we concluded that the coarse sediment deposited in the desert channel of the Yellow River were mostly controlled by the local sediment sources. The analyzed results of the Quartz-Feldspar-Mica (QFM) triangular diagram and the R-factor models of the coarse sediment in the Gansu reach and the desert channel of the Yellow River further confirm that the Ningxia Hedong desert and the Inner Mongolian Wulanbuhe and Kubuqi deserts are the main provenances of the coarse sediment in the desert channel of the Yellow River. Due to the higher fluidity of the fine sediment, they are mainly contributed by the local sediment sources and the tributaries that originated from the loess area of the upper reach of the Yellow River. PMID:20354782

  4. Eastern desert ware : traces of the inhabitants of the eastern desert in Egypt and Sudan during the 4th-6th centuries CE

    NARCIS (Netherlands)

    Barnard, Hans

    2008-01-01

    Several sites in the desert between the Nile and the Red Sea, in Egypt and Sudan, as well as in the Nubian Nile Valley have produced the sherds of decorated hand-made cups and bowls, now identified as Eastern Desert Ware (EDW). Because of their small number and enigmatic origin these sherds have bee

  5. Gulf Coast Clean Energy Application Center

    Energy Technology Data Exchange (ETDEWEB)

    Dillingham, Gavin

    2013-09-30

    The Gulf Coast Clean Energy Application Center was initiated to significantly improve market and regulatory conditions for the implementation of combined heat and power technologies. The GC CEAC was responsible for the development of CHP in Texas, Louisiana and Oklahoma. Through this program we employed a variety of outreach and education techniques, developed and deployed assessment tools and conducted market assessments. These efforts resulted in the growth of the combined heat and power market in the Gulf Coast region with a realization of more efficient energy generation, reduced emissions and a more resilient infrastructure. Specific t research, we did not formally investigate any techniques with any formal research design or methodology.

  6. Project Coast: eugenics in apartheid South Africa.

    Science.gov (United States)

    Singh, Jerome Amir

    2008-03-01

    It is a decade since the exposure of Project Coast, apartheid South Africa's covert chemical and biological warfare program. In that time, attention has been focused on several aspects of the program, particularly the production of narcotics and poisons for use against anti-apartheid activists and the proliferation of both chemical and biological weapons. The eugenic dimension of Project Coast has, by contrast, received scant attention. It is time to revisit the testimony that brought the suggestion of eugenic motives to light, reflect on some of the Truth and Reconciliation Commission's findings and search for lessons that can be taken from this troubled chapter in South Africa's history.

  7. Desert wetlands—Archives of a wetter past

    Science.gov (United States)

    Pigati, Jeffery S.; Springer, Kathleen B.; Manker, Craig R.

    2015-12-16

    Scientists from the U.S. Geological Survey (USGS) are finding evidence of a much wetter past in the deserts of the American Southwest using a most unlikely source—wetlands. Wetlands form in arid environments where water tables approach or breach the ground surface. Often thought of as stagnant and unchanging, new evidence suggests that springs and wetlands responded dynamically to past episodes of abrupt climate change. Multiple cycles of deposition, erosion, and soil formation show that wetlands in the southwestern United States expanded and contracted many times during the past 35,000 years or so, before disappearing altogether as the last glacial period came to a close. USGS scientists are now studying the deposits to determine how closely conditions in the desert were tied to regional and global climate patterns in the past, and what it might mean for the fragile ecosystems in light of anticipated climate change in the future.

  8. Relative abundance of desert tortoises on the Nevada Test Site

    International Nuclear Information System (INIS)

    Seven hundred fifty-nine transects having a total length of 1,191 km were walked during 1981--1986 to determine the distribution and relative abundance of desert tortoises (Gopherus agassizii) on the Nevada Test Site (NTS). The abundance of tortoises on NTS was low to very low relative to other populations in the Mojave Desert. Sign of tortoises was found from 880 to 1,570 m elevation and was more abundant above 1,200 m than has been reported previously for Nevada. Tortoises were more abundant on NTS on the upper alluvial fans and slopes of mountains than in valley bottoms. They also were more common on or near limestone and dolomite mountains than on mountains of volcanic origin

  9. DESERT ECOSYSTEMS: MAPPING, MONITORING & ASSESSMENT USING SATELLITE REMOTE SENSING

    Directory of Open Access Journals (Sweden)

    A. S. Arya

    2012-09-01

    Full Text Available Desert ecosystems are unique but fragile ecosystems , mostly vulnerable to a variety of degradational processes like water erosion, vegetal degradation, salinity, wind erosion , water logging etc. Some researchers consider desertification to be a process of change, while others view it as the end result of a process of change. There is an urgent need to arrest the process of desertification and combat land degradation. Under the auspices of the United Nations Convention to Combat Desertification (UNCCD, Space Applications Centre, Ahmedabad has undertaken the task of mapping, monitoring and assessment of desertification carrying out pilot project in hot and cold desert regions in drylands on 1:50,000 scale followed by systematic Desertification Status Mappaing (DSM of India on 1:500,000 scale.

  10. Tibet's Ali: Asia's Atacama?

    OpenAIRE

    Ye, Quan-Zhi; Su, Meng; Li, Hong; Zhang, Xinmin

    2015-01-01

    The Ngari (Ali) prefecture of Tibet, one of the highest areas in the world, has recently emerged as a promising site for future astronomical observation. Here we use 31 years of reanalysis data from the Climate Forecast System Reanalysis (CFSR) to examine the astroclimatology of Ngari, using the recently-erected Ali Observatory at Shiquanhe (5~047~m above mean sea level) as the representative site. We find the percentage of photometric night, median atmospheric seeing and median precipitable ...

  11. The Mystery of the Gun Turret in the Desert

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-11-30

    The mystery of the gun turret in the desert began with an ingenious idea: to develop a reusable open-air line of sight diagnostic device to support LLNL’s early nuclear weapons development efforts. Obtained from the Mare Island Navy Shipyard (MINS) in January 1957, the gun turret traveled by ship to the Naval Construction Battalion base at Port Hueneme, California, and then by truck to Area 2 in the Yucca Flats valley at the Nevada Nuclear Security Site (NNSS).

  12. Groundwater investigation and modeling - western desert of Iraq

    OpenAIRE

    Al-Muqdadi, Sameh Wisam

    2012-01-01

    The region of interest is part from Iraqi western desert covering an area about 100,000 km². Several of the large wadis such as Hauran, Amij, Ghadaf, Tubal and Ubaiydh traverse the entire region and discharge into the Euphrates River. The present study included the following hydrogeological investigations: Lineaments interpretation was done by using different data sets (SRTM 30 m and Landsat ETM 15m), within different algorithms. Some faults recognized by field survey match rather well ...

  13. Baryon and Lepton Numbers: Life in the Desert

    OpenAIRE

    Fileviez Perez, P.

    2012-01-01

    The simplest theories where we can understand the origin of the baryon and lepton number violating interactions are discussed. We discuss the desert hypothesis in particle physics and the different scenarios where there is no need to assume it. It is shown that the minimal supersymmetric B-L theory predicts lepton number violation at the Large Hadron Collider if supersymmetry is realized at the low scale. We present the BLMSSM where both symmetries, B and L, can be spontaneously broken at the...

  14. The killing desert?: droogte, nomadentradities en ontwikkelingsbestuur bij de Turkana

    OpenAIRE

    P. Wymeersch; Beke, D.

    1987-01-01

    The Turkana are nomadic pastoralists who live in the desert regions of northwestern Kenya. The majority of the Turkana practice no agriculture nor fishing and live exclusively from the products of their livestock (milk, blood and meat). They keep multiple species herds (cattle, camels, goats, sheep and donkeys) in order to buffer the variations in the quality and distribution of vegetal resources and water requirements. The Turkana were one of many affected by several droughts. Although the f...

  15. Fasting-induced daily torpor in desert hamsters (Phodopus roborovskii).

    Science.gov (United States)

    Chi, Qing-Sheng; Wan, Xin-Rong; Geiser, Fritz; Wang, De-Hua

    2016-09-01

    Daily torpor is frequently expressed in small rodents when facing energetically unfavorable ambient conditions. Desert hamsters (Phodopus roborovskii, ~20g) appear to be an exception as they have been described as homeothermic. However, we hypothesized that they can use torpor because we observed reversible decreases of body temperature (Tb) in fasted hamsters. To test this hypothesis we (i) randomly exposed fasted summer-acclimated hamsters to ambient temperatures (Tas) ranging from 5 to 30°C or (ii) supplied them with different rations of food at Ta 23°C. All desert hamsters showed heterothermy with the lowest mean Tb of 31.4±1.9°C (minimum, 29.0°C) and 31.8±2.0°C (minimum, 29.0°C) when fasted at Ta of 23°C and 19°C, respectively. Below Ta 19°C, the lowest Tb and metabolic rate increased and the proportion of hamsters using heterothermy declined. At Ta 5°C, nearly all hamsters remained normothermic by increasing heat production, suggesting that the heterothermy only occurs in moderately cold conditions, perhaps to avoid freezing at extremely low Tas. During heterothermy, Tbs below 31°C with metabolic rates below 25% of those during normothermia were detected in four individuals at Ta of 19°C and 23°C. Consequently, by definition, our observations confirm that fasted desert hamsters are capable of shallow daily torpor. The negative correlation between the lowest Tbs and amount of food supply shows that heterothermy was mainly triggered by food shortage. Our data indicate that summer-acclimated desert hamsters can express fasting-induced shallow daily torpor, which may be of significance for energy conservation and survival in the wild. PMID:27215346

  16. Lake salinity variations resulting from wind direction, Gobi Desert, China

    Science.gov (United States)

    Bradley, D. C.; Cartwright, I.; Currell, M.

    2010-12-01

    The southern reaches of the Gobi desert, central China, host a large number (~50) of shallow (body. This process is susceptible to even small disturbances. In the developed lakes, this trend is no longer observed, as the system has been interrupted by buildings causing changes to the wind flow, or alternatively, animals and/or human population have altered the water flow, simply through the act of entering the lakes and mixing the lake waters.

  17. Pinpointing the desert of the Ruoqiang County, Western China

    CERN Document Server

    Sparavigna, Amelia Carolina

    2012-01-01

    A man-made texture on the desert soil of a county of the Western China is visible in satellite images, more than 8 kilometers long and 50 meters wide. This seems to be the result of a detailed geophysical survey of the region that led to the discovery of a large nickel ore. Therefore, the analysis of the satellite imagery, performed to find such textures created by the sampling of soils, can help anticipating information on the economical potentialities of a site.

  18. Sterol contents from some fabaceous medicinal plants of Rajasthan desert

    Directory of Open Access Journals (Sweden)

    B.B.S.Kapoor

    2013-12-01

    Full Text Available Evaluation of sterol contents from three selected medicinal plant species of Fabaceae family growing in Rajasthan Desert was carried out. The roots, shoots and fruits of Clitoria ternatea, Sesbania bispinosa and Tephrosia purpurea were analysed for sterol contents. - Sitosterol and Stigmasterol were isolated and identified. Maximum sterol contents were observed in shoots of Sesbania bispinosa (0.29 mg/g.d.w., whereas minimum in roots of Tephrosia purpurea(0.15mg/g.d.w.

  19. Patton's tracks in the Mojave Desert, USA: An ecological legacy

    Science.gov (United States)

    Belnap, J.; Warren, S.D.

    2002-01-01

    Recovery of soil properties from World War II-era military training exercises in the Mojave Desert was measured approximately 55 years following disturbance. Tracks from military vehicles were still visible, particularly in areas of desert pavement. Soil penetrability was much lower in visible tracks than outside the tracks. Soils in tracks had fewer rocks in the top 10 cm of the soil profile than adjacent untracked soils. Larger particles (> 4.8 mm) formed a moderately well-developed pavement outside of the tracks, while smaller, loose particles (???4.8 mm) dominated the surface of the tracks. The time required to restore the desert pavement is likely to be measured in centuries. Based on biomass estimates, the cyanobacterial component of biological soil crusts had recovered 46-65% in tracks, compared to outside the tracks. Overall recovery of lichen cover has been much slower. Under plant canopies, cover of Collema tenax was not significantly different between areas inside and outside the tracks; however, recovery of Catapyrenium squamulosum was only 36%. In plant interspaces with less favorable moisture and temperature conditions, C. tenax showed a 6% recovery and C. squamulosum a 3% recovery. Assuming recovery of the biological soil crust is linear, and complete only when the most sensitive species (C. squamulosum) has fully recovered in the most limiting microhabitats (plant interspaces), it may require almost two millennia for full recovery of these areas.

  20. Study of the microwave emissivity characteristics over Gobi Desert

    International Nuclear Information System (INIS)

    The microwave emissivity represents the capacity of the thermal radiation of the surface, and it is the significant parameter for understanding the geophysical processes such as surface energy budget and surface radiation. Different land covers have different emissivity properties, and the Gobi Desert in Central Asia seriously impact the sandstorms occur and develop in China, because of its special geographical environment and surface soil characteristics. In this study half-month averaged microwave emissivity from March 2003 to February 2004 over the Gobi Desert has been estimated. Emissivities in this area at different frequencies, polarization and their seasonal variations are discussed respectively. The results showed that emissivity polarization difference decrease as the frequency increases, and the polarization difference is large (0.03–0.127). The H polarization emissivity increases with increasing frequency, but the V-polarized microwave emissivity is reduced with increasing frequency because of the body scattering. In winter, emissivity decreases sharply in snow covered area, especially for higher frequencies (such as 89GHz). In addition, we compared emissivity with MODIS NDVI data at the same time in the Gobi Desert, and the results indicate that NDVI derived the good negative correlation with microwave emissivity polarization difference at 37GHz

  1. Microbial communities in a High Arctic polar desert landscape

    Directory of Open Access Journals (Sweden)

    Clare M McCann

    2016-03-01

    Full Text Available The High Arctic is dominated by polar desert habitats whose microbial communities are poorly understood. In this study, we used next generation sequencing to describe the α- and β-diversity of polar desert soils from the Kongsfjorden region of Svalbard. Ten phyla consistently dominated the soils and accounted for 95 % of all sequences, with Proteobacteria, Actinobacteria and Chloroflexi being the dominant lineages. In contrast to previous investigations of Arctic soils, Acidobacterial relative abundances were low as were the Archaea throughout the Kongsfjorden polar desert landscape. Lower Acidobacterial abundances were attributed to the circumneutral soil pH in this region which has resulted from the weathering of the underlying carbonate geology. In addition, we correlated previously measured geochemical variables to determine potential controls on the communities. Soil phosphorus, pH, nitrogen and calcium significantly correlated with β-diversity indicating a landscape scale lithological control of soil nutrients which in turn influenced community composition. In addition, soil phosphorus and pH significantly correlated with α- diversity, specifically the Shannon diversity and Chao 1 richness indices.

  2. Desert shrub stemflow and its significance in soil moisture replenishment

    Directory of Open Access Journals (Sweden)

    X.-P. Wang

    2011-02-01

    Full Text Available Stemflow of xerophytic shrubs represents a significant component of water replenishment to the soil-root system influencing water utilization of plant roots at the stand scale, especially in water scarce desert ecosystems. In this study, stemflow of Caragana korshinskii was quantified by an aluminum foil collar collection method on re-vegetated sand dunes of the Shapotou restored desert ecosystem in northwestern China. Time domain reflectometry probes were inserted horizontally at 20 different soil profile depths under the C. korshinskii shrub to monitor soil moisture variation at hourly intervals. Results indicated that 2.2 mm precipitation was necessary for the generation of stemflow for C. korshinskii. Stemflow averaged 8% of the gross precipitation and the average funnelling ratio was as high as 90. The soil moisture in the uppermost soil profile was strongly correlated with individual rainfall and the stemflow strengthened this relationship. Therefore, it is favourable for the infiltrated water redistribution in the deeper soil profile of the root zone. Consequently, stemflow contributes significantly to a positive soil moisture balance in the root zone and the replenishment of soil moisture at deeper soil layers. This plays an important role in plant survival and the general ecology of arid desert environments.

  3. Study of the microwave emissivity characteristics over Gobi Desert

    Science.gov (United States)

    Yubao, Qiu; Lijuan, Shi; Wenbo, Wu

    2014-03-01

    The microwave emissivity represents the capacity of the thermal radiation of the surface, and it is the significant parameter for understanding the geophysical processes such as surface energy budget and surface radiation. Different land covers have different emissivity properties, and the Gobi Desert in Central Asia seriously impact the sandstorms occur and develop in China, because of its special geographical environment and surface soil characteristics. In this study half-month averaged microwave emissivity from March 2003 to February 2004 over the Gobi Desert has been estimated. Emissivities in this area at different frequencies, polarization and their seasonal variations are discussed respectively. The results showed that emissivity polarization difference decrease as the frequency increases, and the polarization difference is large (0.03-0.127). The H polarization emissivity increases with increasing frequency, but the V-polarized microwave emissivity is reduced with increasing frequency because of the body scattering. In winter, emissivity decreases sharply in snow covered area, especially for higher frequencies (such as 89GHz). In addition, we compared emissivity with MODIS NDVI data at the same time in the Gobi Desert, and the results indicate that NDVI derived the good negative correlation with microwave emissivity polarization difference at 37GHz.

  4. The evolution of deserts with climatic changes in China since 150 ka B.P.

    Institute of Scientific and Technical Information of China (English)

    董光荣; 陈惠忠; 王贵勇; 李孝泽; 邵亚军; 金炯

    1997-01-01

    According to the bioclimatic zones, dune mobility and the fabric characteristics of stratigraphic sedimentary facies, the deserts in China are divided into Eastern, Western, Central and Northwestern deserts. Based on the records of stratigraphical facies, climatic proxies, historical data, etc. in each desert region, the evolution of deserts with climatic changes in time and space since 150 ka B. P. in China are dealt with; then the evolution of deserts in relation to the glacial climatic fluctuations caused by solar radiation changes, underlying surface variation and their feedback mechanism is discussed through comparison with global records; finally, in consideration of global wanning due to increasing of greenhouse gases such as CO2, the possible tendency of the evolution of deserts and the climatic changes is discussed.

  5. The Atacama Cosmology Telescope: Sunyaev-Zel'dovich selected galaxy clusters at 148 GHz from three seasons of data

    Energy Technology Data Exchange (ETDEWEB)

    Hasselfield, Matthew; Hlozek, Renée [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Hilton, Matt [Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Durban, 4041 (South Africa); Marriage, Tobias A.; Crichton, Devin; Gralla, Megan B. [Dept. of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Addison, Graeme E.; Halpern, Mark [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z4 (Canada); Barrientos, L. Felipe; Dünner, Rolando [Departamento de Astronomía y Astrofísica, Facultad de Física, Pontificía Universidad Católica, Casilla 306, Santiago 22 (Chile); Battaglia, Nicholas [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Battistelli, Elia S. [Department of Physics, University of Rome ' ' La Sapienza' ' , Piazzale Aldo Moro 5, I-00185 Rome (Italy); Bond, J. Richard; Hajian, Amir; Hincks, Adam D. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON, M5S 3H8 (Canada); Das, Sudeep [High Energy Physics Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, IL 60439 (United States); Devlin, Mark J.; Dicker, Simon R. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Dunkley, Joanna [Department of Astrophysics, Oxford University, Oxford, OX1 3RH (United Kingdom); Fowler, Joseph W., E-mail: mhasse@astro.princeton.edu, E-mail: hiltonm@ukzn.ac.za, E-mail: marriage@pha.jhu.edu [NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States); and others

    2013-07-01

    We present a catalog of 68 galaxy clusters, of which 19 are new discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the Atacama Cosmology Telescope (ACT) survey on the celestial equator. With this addition, the ACT collaboration has reported a total of 91 optically confirmed, SZ detected clusters. The 504 square degree survey region includes 270 square degrees of overlap with SDSS Stripe 82, permitting the confirmation of SZ cluster candidates in deep archival optical data. The subsample of 48 clusters within Stripe 82 is estimated to be 90% complete for M{sub 500c} > 4.5 × 10{sup 14}M{sub s}un and redshifts 0.15 < z < 0.8. While a full suite of matched filters is used to detect the clusters, the sample is studied further through a ''Profile Based Amplitude Analysis'' using a statistic derived from a single filter at a fixed θ{sub 500} = 5.'9 angular scale. This new approach incorporates the cluster redshift along with prior information on the cluster pressure profile to fix the relationship between the cluster characteristic size (R{sub 500}) and the integrated Compton parameter (Y{sub 500}). We adopt a one-parameter family of ''Universal Pressure Profiles'' (UPP) with associated scaling laws, derived from X-ray measurements of nearby clusters, as a baseline model. Three additional models of cluster physics are used to investigate a range of scaling relations beyond the UPP prescription. Assuming a concordance cosmology, the UPP scalings are found to be nearly identical to an adiabatic model, while a model incorporating non-thermal pressure better matches dynamical mass measurements and masses from the South Pole Telescope. A high signal to noise ratio subsample of 15 ACT clusters with complete optical follow-up is used to obtain cosmological constraints. We demonstrate, using fixed scaling relations, how the constraints depend on the assumed gas model if only SZ measurements are used, and

  6. The Atacama Cosmology Telescope: Sunyaev-Zel'dovich selected galaxy clusters at 148 GHz from three seasons of data

    International Nuclear Information System (INIS)

    We present a catalog of 68 galaxy clusters, of which 19 are new discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the Atacama Cosmology Telescope (ACT) survey on the celestial equator. With this addition, the ACT collaboration has reported a total of 91 optically confirmed, SZ detected clusters. The 504 square degree survey region includes 270 square degrees of overlap with SDSS Stripe 82, permitting the confirmation of SZ cluster candidates in deep archival optical data. The subsample of 48 clusters within Stripe 82 is estimated to be 90% complete for M500c > 4.5 × 1014Msun and redshifts 0.15 500 = 5.'9 angular scale. This new approach incorporates the cluster redshift along with prior information on the cluster pressure profile to fix the relationship between the cluster characteristic size (R500) and the integrated Compton parameter (Y500). We adopt a one-parameter family of ''Universal Pressure Profiles'' (UPP) with associated scaling laws, derived from X-ray measurements of nearby clusters, as a baseline model. Three additional models of cluster physics are used to investigate a range of scaling relations beyond the UPP prescription. Assuming a concordance cosmology, the UPP scalings are found to be nearly identical to an adiabatic model, while a model incorporating non-thermal pressure better matches dynamical mass measurements and masses from the South Pole Telescope. A high signal to noise ratio subsample of 15 ACT clusters with complete optical follow-up is used to obtain cosmological constraints. We demonstrate, using fixed scaling relations, how the constraints depend on the assumed gas model if only SZ measurements are used, and show that constraints from SZ data are limited by uncertainty in the scaling relation parameters rather than sample size or measurement uncertainty. We next add in seven clusters from the ACT Southern survey, including their dynamical mass measurements, which are based on galaxy velocity dispersions and

  7. Emission of sunscreen salicylic esters from desert vegetation and their contribution to aerosol formation

    OpenAIRE

    Matsunaga, ECB

    2008-01-01

    Biogenic volatile organic compounds (BVOC) produced by plants are known to have an important role in atmospheric chemistry. However, our knowledge of the range of BVOCs produced by different plant processes is still expanding, and there remain poorly understood categories of BVOCs. In this study, emissions of a novel class of BVOC emissions were investigated in a desert region. Our study considered 8 species of common desert plants: blackbrush (Coleogyne ramosissima), desert willow (Chilopsis...

  8. Longshore sediment transport along the Indian coast

    Digital Repository Service at National Institute of Oceanography (India)

    Chandramohan, P.; Nayak, B.U.

    sediment transport rate is high (15-20 x 10 super(5) m super(3)) along the coasts of South Orissa, North Tamilnadu, South Kerala, North Karnataka and South Gujarat, whilst, it is comparatively less (5-10 x 10 super(5) m super(3)) along the South Tamilnadu...

  9. The Kenya Coast in national perspective

    NARCIS (Netherlands)

    Meilink, H.A.; Hoorweg, J.; Foeken, D.W.J.; Obudho, R.A.

    2000-01-01

    Despite its economic and cultural potential, the Kenya Coast finds itself in a marginal position. This collective volume traces the causes behind this situation and analyses it from different angles: political, economic and social. Most of the papers included in this volume were first presented at a

  10. The Kenya coast : A regional study

    NARCIS (Netherlands)

    Hoorweg, J.; Foeken, D.W.J.; Obudho, R.A.; Hoorweg, J.; Foeken, D.W.J.; Obudho, R.A.

    2000-01-01

    Despite its economic and cultural potential, the Kenya Coast finds itself in a marginal position. This collective volume traces the causes behind this situation and analyses it from different angles: political, economic and social. Most of the papers included in this volume were first presented at a

  11. Erosion Pressure on the Danish Coasts

    DEFF Research Database (Denmark)

    Sørensen, Carlo Sass; Sørensen, Per; Kroon, Aart;

    by the ocean, coastal erosion issues become increasingly more important to the human values at risk. Along many Danish coastlines, hard structures already act as coastal protection in the form of groins, breakwaters, revetments etc. These eroding coasts however still lack sand and where the public, in general...

  12. Rickettsiae in Gulf Coast Ticks, Arkansas, USA

    OpenAIRE

    Trout, Rebecca; Steelman, C Dayton; Szalanski, Allen L.; Williamson, Phillip C

    2010-01-01

    To determine the cause of spotted fever cases in the southern United States, we screened Gulf Coast ticks (Amblyomma maculatum) collected in Arkansas for rickettsiae. Of the screened ticks, 30% had PCR amplicons consistent with Rickettsia parkeri or Candidatus Rickettsia amblyommii.

  13. Seasons and nutrition at the Kenya coast

    NARCIS (Netherlands)

    Hoorweg, J.; Foeken, D.W.J.; Klaver, W.

    1995-01-01

    This monograph reports on the seasonal fluctuations in food and nutrition that occur in Coast Province, Kenya, on the basis of data gathered during five survey rounds held in selected locations in Kwale and Kilifi districts between mid 1985 and late 1986. The study population seems to have developed

  14. ETV Program Production in the Ivory Coast.

    Science.gov (United States)

    Evans, Stella; Klees, Steven

    The efficiency of educational broadcasting in the Ivory Coast is assessed from the standpoint of what and how physical and human resources are utilized. Information was obtained by reviewing the large volume of documents that have been published about the project and through interviewing personnel involved in its management and operation. The…

  15. Fire Impacts on the Mojave Desert Ecosystem: Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Fenstermaker Lynn

    2012-01-01

    The Nevada National Security Site (NNSS) is located within the Mojave Desert, which is the driest region in North America. Precipitation on the NNSS varies from an annual average of 130 millimeters (mm; 5.1 inches) with a minimum of 47 mm (1.9 inches) and maximum of 328 mm (12.9 inches) over the past 15 year period to an annual average of 205 mm (8.1 inches) with an annual minimum of 89 mm (3.5 inches) and maximum of 391 mm (15.4 inches) for the same time period; for a Frenchman Flat location at 970 meters (m; 3182 feet) and a Pahute Mesa location at 1986 m (6516 feet), respectively. The combination of aridity and temperature extremes has resulted in sparsely vegetated basins (desert shrub plant communities) to moderately vegetated mountains (mixed coniferous forest plant communities); both plant density and precipitation increase with increasing elevation. Whereas some plant communities have evolved under fire regimes and are dependent upon fire for seed germination, plant communities within the Mojave Desert are not dependent on a fire regime and therefore are highly impacted by fire (Brown and Minnich, 1986; Brooks, 1999). As noted by Johansen (2003) natural range fires are not prevalent in the Mojave and Sonoran Deserts because there is not enough vegetation present (too many shrub interspaces) to sustain a fire. Fire research and hence publications addressing fires in the Southwestern United States (U.S.) have therefore focused on forest, shrub-steppe and grassland fires caused by both natural and anthropogenic ignition sources. In the last few decades, however, invasion of mid-elevation shrublands by non-native Bromus madritensis ssp. rubens and Bromus tectorum (Hunter, 1991) have been highly correlated with increased fire frequency (Brooks and Berry, 2006; Brooks and Matchett, 2006). Coupled with the impact of climate change, which has already been shown to be playing a role in increased forest fires (Westerling et al., 2006), it is likely that the fire

  16. GLOBAL WARMING: DESERT HEAT COLLECTION AND CONVERSION INTO ELECTRICITY

    Energy Technology Data Exchange (ETDEWEB)

    Muftah M. Elarbash [Waves Environmental Ltd., Tajura, Tripoli (Libya)

    2008-09-30

    Waves Environmental through its founders has made advances since 1983 in researching, and on the way to developing and creating a clean energy source as a global alternative to fossil fuel and to provide renewable clean electric energy to satisfy the global need for energy. A 2,500 km2 of desert land would is planned to construct an operational physical model that would collect sufficient desert heat to generate about 70,000 MW. This large scale physical model would be used for testing and technology development. The model would be converted at a latter phase of the research and development to a commercial prototype for further testing and for fine tuning of the developed technology. Once the technology is fully developed and is ready for implementation, the first large scale desert heat collection and conversion into electricity (DHCCE) plant would be built. The plant would sit on about 10,000 km2 of desert land to generate about 300,000 MW. The project principle is to simulate global warming in energy trapping and create local isolated climates within the ambient climate. Several local low pressure regions would be created within the nearly constant high pressure desert climate. Keep and maintain a constant low pressure at the isolated mini climates, internal winds would be stimulated to blow in constant velocities. The velocities would be maintained at a level where wind speed is high enough to produce an adequate level of mechanical energy that is economically convertible into electricity. The overall energy conversion efficiency should be maintained at 8% or higher. The investment returns of the project are also substantial. The whole world community can benefit in cash terms. Energy would be cheap enough to be provided to each household at nearly half of what is paid today. With an annual production of 131,400 TWh in 2007 increasing at a 2.3% annual rate and estimating the average selling price of the renewable KWh to be $0.06, the annual revenue in 2018

  17. Regular Cosmogenic Nuclide Dosing of Sediment Moving Down Desert Piedmonts

    Science.gov (United States)

    Nichols, K. K.; Bierman, P. R.; Hooke, R. L.; Eppes, M. C.; Persico, L.; Caffee, M.; Finkel, R.

    2001-12-01

    Low-gradient alluvial piedmonts are common in desert areas throughout the world; however, long-term rates of processes that modify these landscapes are poorly understood. Using cosmogenic 10Be and 26Al, we attempt to quantify the long-term (>103 y) behavior of desert piedmonts in Southern California. We measured the activity of 10Be and 26Al in three samples of drainage basin alluvium and six amalgamated samples from transects spaced at 1-km intervals down a piedmont in Fort Irwin, Mojave Desert, California. Each transect sample consists of sediment from 21 collection sites spaced at 150 m intervals. Such sampling averages the variability of nuclide activity between sub-sample locations and thus gives a long-term dosing history of sediment as it is transported from uplands to the distal piedmont. The piedmont is heavily used during military training exercises during which hundreds of wheeled and tracked vehicles traverse the surface. The piedmont surface is planar, and fan-head incision is minimal at the rangefront decreasing to zero between the first and second transects, 1.5 km from the rangefront. 10Be activity increases steadily from 5.87 X 105 atoms g-1 at the rangefront to 1.02 X 6 atoms g-1 at the piedmont bottom. Nuclide activity and distance are well correlated (r2 = 0.95) suggesting that sediment is dosed uniformly as it is transported down piedmont. We have measured similar increases in nuclide activity in transect samples collected from two other Mojave Desert piedmonts, those fringing the Iron and Granite Mountains (Nichols et al, in press, Geomorphology). These piedmonts have nuclide activities that also correlate well with distance (r2 = 0.98 and 0.96, respectively) from their rangefronts, but nuclides increase at a lower rate down piedmont. Modeled sediment transport speeds for the Iron and Granite Mountain piedmonts are decimeters per year. The regular increase in nuclide activities down three different Mojave Desert piedmonts suggests that

  18. Strategic sustainable development of groundwater in Thar desert of Pakistan

    International Nuclear Information System (INIS)

    Thar Desert forms the extreme southeastern part of Pakistan, covering about 50,000 km/sup 2/ area. It is one of the densely populated deserts of the world. Population of Thar is living primarily on limited agricultural products and by raising goats, sheep, cattle, and camels. The region is characterized by parallel chains of the NE-SW trending parabolic stable sanddunes having desertic varieties of vegetation, generally on windward sides, up to the crests. Interdunal areas are favourable for agricultural activities, where crops are mainly dependent on rainwater. Average rainfall is significant but inconsistent, due to recurrent drought-cycles causing inverse impact on food-production and socio-economic development. In spite of extensive groundwater- exploration projects, accomplished by a number of organizations, the water-crisis of the region could not be controlled, most probably due to lack of systematic exploration and development of deep groundwater potential. Management of the available water- resources is also not adequate, even to sustain a short period of drought-cycle. On recurrence of a drought-cycle, a significant section of the population is compelled to migrate towards other parts of the Sindh province, which affects their socio-economic stability. An integrated research study, based on geo-electric scanning, drilling and seismic-data analyses, has been carried out to delineate subsurface hydro-geological conditions beneath the Thar Desert. Regional gradient maps of surface elevation, top of subsurface Oxidized Zone, top of coal-bearing formation(s) and the deeply buried basement have been prepared, covering almost the whole of That Desert. These gradient maps, analyzed in conjunction with the annual rainfall data, reveal the existence of encouraging subsurface hydrogeological conditions, associated with the sedimentary sequences and the basement. From the results of the study, it is observed that perch water aquifers, commonly being utilized

  19. The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey

    CERN Document Server

    Das, Sudeep; Ade, Peter A R; Aguirre, Paula; Amir, Mandana; Appel, John W; Barrientos, L Felipe; Battistelli, Elia S; Bond, J Richard; Brown, Ben; Burger, Bryce; Chervenak, Jay; Devlin, Mark J; Dicker, Simon R; Doriese, W Bertrand; Dunkley, Joanna; Dünner, Rolando; Essinger-Hileman, Thomas; Fisher, Ryan P; Fowler, Joseph W; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hernández-Monteagudo, Carlos; Hilton, Gene C; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Huffenberger, Kevin M; Hughes, David H; Hughes, John P; Infante, Leopoldo; Irwin, Kent D; Juin, Jean Baptiste; Kaul, Madhuri; Klein, Jeff; Kosowsky, Arthur; Lau, Judy M; Limon, Michele; Lin, Yen-Ting; Lupton, Robert H; Marsden, Danica; Martocci, Krista; Mauskopf, Phil; Menanteau, Felipe; Moodley, Kavilan; Moseley, Harvey; Netterfield, Calvin B; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Partridge, Bruce; Reid, Beth; Sehgal, Neelima; Sherwin, Blake D; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Trac, Hy; Tucker, Carole; Warne, Ryan; Wollack, Ed; Zhao, Yue

    2010-01-01

    We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results clearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the {\\Lambda}CDM cosmological model. At l > 3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8{\\sigma} level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.

  20. THE ATACAMA COSMOLOGY TELESCOPE: A MEASUREMENT OF THE COSMIC MICROWAVE BACKGROUND POWER SPECTRUM AT 148 AND 218 GHz FROM THE 2008 SOUTHERN SURVEY

    International Nuclear Information System (INIS)

    We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results clearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the ΛCDM cosmological model. At l>3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8σ level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.

  1. Modulation of CMB polarization with a warm rapidly-rotating half-wave plate on the Atacama B-Mode Search (ABS) instrument

    CERN Document Server

    Kusaka, A; Appel, J W; Gallardo, P; Irwin, K D; Jarosik, N; Nolta, M R; Page, L A; Parker, L P; Raghunathan, S; Sievers, J L; Simon, S M; Staggs, S T; Visnjic, K

    2014-01-01

    We evaluate the modulation of Cosmic Microwave Background (CMB) polarization using a rapidly-rotating, half-wave plate (HWP) on the Atacama B-Mode Search (ABS). After demodulating the time-ordered-data (TOD), we find a significant reduction of atmospheric fluctuations. The demodulated TOD is stable on time scales of 500-1000 seconds, corresponding to frequencies of 1-2 mHz. This facilitates recovery of cosmological information at large angular scales, which are typically available only from balloon-borne or satellite experiments. This technique also achieves a sensitive measurement of celestial polarization without differencing the TOD of paired detectors sensitive to two orthogonal linear polarizations. This is the first demonstration of the ability to remove atmospheric contamination at these levels from a ground-based platform using a rapidly-rotating HWP.

  2. Study on the Land Reclamation of Oilfield of Gurbantunggut Desert in Junggar Basin

    Institute of Scientific and Technical Information of China (English)

    Liang; LI; Xuezhong; ZHENG; Xusheng; SHAO; Caichuan; WANG; Min; Xu

    2013-01-01

    The exploration and development of oilfield results in damages to land resources. Along with the further development of petroleum in the Gurbantunggut Desert, the fragile ecological environment and land resource was suffering much more damage. Vegetation degradation and desertification become more prominent. In response to the damage to the fragile ecological environment and oilfield in the Gurbantunggut Desert, limit condition method was used to evaluate the suitability of land reclamation suitability. Results suggested that the main restraining factors for land reclamation were soil condition and water resources. Based on the effect and shortage of oilfield in the Gurbantunggut Desert Oilfield, the reclamation of oilfield in the Gurbantunggut desert was discussed.

  3. Species composition,distribution patterns and ecological functions of biological soil crusts in the Gurbantunggut Desert

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    As one of the most important biological factors that maintain the stability of the largest fixed and semi-fixed desert in China,the Gurbantunggut Desert,the biological soil crusts (BSCs) develop well and play critical ecological roles in the desert ecosystem. In this paper,we briefly summarize our research findings since 2002 including species composition,distribution pattern and ecological functions of BSCs in the desert. Our results indicate abundant species diversity of BSCs in the Gurbantunggut Desert in comparison to other deserts in China. At the scales of sand dune or whole desert,the distribution patterns of BSCs are location-specific. The existence of BSCs in this desert could:(1) accelerate the formation of desert soil and the weathering of minerals; (2) accumulate organic matter in surface soil through related species in soil crusts; (3) enhance the abilities of sand surface to resist wind erosion; (4) influence seed germination of vascular plants; and (5) enhance the production of dew deposition on sandy soil surface.

  4. On scientific expedition tourism of desert region: a case of eastern Ulan Buh Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Desert-based adventure tourism is a rapidly expanding tourism market segment after the late 20th century around the world.Perhaps the most significant factor in the development of desert adventure tourism is the extent to which common tourists are really engaged in scientific expedition.Inner Mongolia has long been considered as the resources accumulation area of desert tourism.The investigation on the Ulan Buh Desert has discovered that the desert animals,the vegetation,the insects,the fungus,the landform and the climate are impressive for both the researchers and the mass tourists.After the resources investigation a survey was carried out in 2007 to get the detailed information of the tourists attitude toward the planning desert scientific product in the Ulan Buh Desert.Based on the resources and market analysis,this paper tries to make a planning of the desert scientific expedition tour of the Ulan Buh Desert.The planning includes the functional division,expedition route design,tour-explaining system,facility of safety guaranty and service planning,and the professional training base.

  5. Polarization difference imaging for millimeter-wave in a desert environment

    Science.gov (United States)

    Wilson, John P.; Schuetz, Christopher A.; Stein, Edwin L., Jr.; Samluk, Jesse P.; Mackrides, Daniel G.; Prather, Dennis W.

    2010-10-01

    The low attenuation of millimeter-wave radiation propagating through sandstorms has created an interest in using millimeter-wave imagers in desert environments. The ground in desert environments can have significant differences in polarization properties depending on the angle of observation. Perturbations to the natural desert surface will change these polarization properties and by using a polarization difference technique these changes are highlighted. This technique has been applied to millimeter-wave images from a desert environment for several different objects including holes in the ground, footsteps, and changes to the surface created by digging.

  6. Epifluorescent direct counts of bacteria and viruses from topsoil of various desert dust storm regions.

    Science.gov (United States)

    Gonzalez-Martin, Cristina; Teigell-Perez, Nuria; Lyles, Mark; Valladares, Basilio; Griffin, Dale W

    2013-01-01

    Topsoil from arid regions is the main source of dust clouds that move through the earth's atmosphere, and microbial communities within these soils can survive long-range dispersion. Microbial abundance and chemical composition were analyzed in topsoil from various desert regions. Statistical analyses showed that microbial direct counts were strongly positively correlated with calcium concentrations and negatively correlated with silicon concentrations. While variance between deserts was expected, it was interesting to note differences between sample sites within a given desert region, illustrating the 'patchy' nature of microbial communities in desert environments. PMID:22989672

  7. Potential for deserts to supply reliable renewable electric power

    Science.gov (United States)

    Labordena, Mercè; Lilliestam, Johan

    2015-04-01

    To avoid dangerous climate change, the electricity systems must be decarbonized by mid-century. The world has sufficient renewable electricity resources for complete power sector decarbonization, but an expansion of renewables poses several challenges for the electricity systems. First, wind and solar PV power are intermittent and supply-controlled, making it difficult to securely integrate this fluctuating generation into the power systems. Consequently, power sources that are both renewable and dispatchable, such as biomass, hydro and concentrating solar power (CSP), are particularly important. Second, renewable power has a low power density and needs vast areas of land, which is problematic both due to cost reasons and due to land-use conflicts, in particular with agriculture. Renewable and dispatchable technologies that can be built in sparsely inhabited regions or on land with low competition with agriculture would therefore be especially valuable; this land-use competition greatly limits the potential for hydro and biomass electricity. Deserts, however, are precisely such low-competition land, and are at the same time the most suited places for CSP generation, but this option would necessitate long transmission lines from remote places in the deserts to the demand centers such as big cities. We therefore study the potential for fleets of CSP plants in the large deserts of the world to produce reliable and reasonable-cost renewable electricity for regions with high and/or rapidly increasing electricity demand and with a desert within or close to its borders. The regions in focus here are the European Union, North Africa and the Middle East, China and Australia. We conduct the analysis in three steps. First, we identify the best solar generation areas in the selected deserts using geographic information systems (GIS), and applying restrictions to minimize impact on biodiversity, soils, human heath, and land-use and land-cover change. Second, we identify

  8. Dime cómo escribes y te diré quién eres: Textualizaciones del campesinado indígena de la Puna de Atacama

    Directory of Open Access Journals (Sweden)

    Alejandro F. Haber

    2006-12-01

    Full Text Available Presentamos un análisis de las estrategias textuales de representación del campesinado indígena que se han desarrollado tanto desde la disciplina arqueológica como desde la etnohistoria. Cada una de estas disciplinas, a lo largo del tiempo, ha defendido sus modos diferenciales de acceso al pasado frente a los de la otra. Es nuestra intención mostrar cómo, a pesar de las diferencias marcadas en esas discusiones, ambas disciplinas parten de presupuestos comunes respecto del objeto de estudio por ellas construido. Se tomaron para los análisis diferentes textos referidos a la arqueología, historia o etnohistoria de la Puna de Atacama desde la conquista hasta el siglo XIX y se confrontaron con los resultados de nuestras propias investigaciones. Finalmente argumentamos que los discursos académicos nos dicen más acerca de quién escribe que sobre quienes lo hacen.Archaeological and ethnohistorical textual practices regarding indigenous peasantry are analyzed. Both disciplines, along their history, have defended their own specific methods of approaching the past against the methods of the other. We intend to show how, despite the differences noticed on those discussions, both disciplines are based on common cultural biases about their subject matter. For analytical purposes we use different texts from archaeology, history or ethnohistory of the Atacama Plateau from the Castilian Conquest to the twentieth century, which are also confronted with the results of our own research. It is argued that academic discourses tell us more about who writes than about who is being described.

  9. Invited article: millimeter-wave bolometer array receiver for the Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument.

    Science.gov (United States)

    Schwan, D; Ade, P A R; Basu, K; Bender, A N; Bertoldi, F; Cho, H-M; Chon, G; Clarke, John; Dobbs, M; Ferrusca, D; Güsten, R; Halverson, N W; Holzapfel, W L; Horellou, C; Johansson, D; Johnson, B R; Kennedy, J; Kermish, Z; Kneissl, R; Lanting, T; Lee, A T; Lueker, M; Mehl, J; Menten, K M; Muders, D; Pacaud, F; Plagge, T; Reichardt, C L; Richards, P L; Schaaf, R; Schilke, P; Sommer, M W; Spieler, H; Tucker, C; Weiss, A; Westbrook, B; Zahn, O

    2011-09-01

    The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 μK(CMB)√s (NEy of 3.5 × 10(-4) √s). We have also demonstrated upgraded detectors with improved sensitivity of 530 μK(CMB)√s (NEy of 2.2 × 10(-4) √s). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope. PMID:21974566

  10. US Coast Guard Stations in Louisiana, Geographic NAD83, USCG [coast_guard_stations_USCG_1997

    Data.gov (United States)

    Louisiana Geographic Information Center — This is is a point dataset for the locations and attributes of eight US Coast Guard stations in Louisiana. The attributes include name, address, latitude (NAD27),...

  11. West Coast DA Event data - West Coast Toxic Pseudo-nitzschia bloom

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Beginning in the spring of 2015 the US West Coast began to experience the most wide-spread toxic Pseudo-nitzschia bloom to date, after approximately eight years...

  12. California coast sablefish - Reproductive Life History Analysis of Sablefish Populations off the Washington and California Coasts

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sablefish (Anoplopoma fimbria) have a wide distribution along the Pacific coast, extending from Baja California to Alaska, the Bering Sea and through to the eastern...

  13. Washington coast sablefish - Reproductive Life History Analysis of Sablefish Populations off the Washington and California Coasts

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sablefish (Anoplopoma fimbria) have a wide distribution along the Pacific coast, extending from Baja California to Alaska, the Bering Sea and through to the eastern...

  14. Studies on sediment transport along Kerala Coast, south west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sajeev, R.; Chandramohan, P.; Josanto, V.; Sanakaranarayanan, V.N.

    Longshore sediment transport characteristics of the Kerala Coast have been examined to delineate various physical processes affecting the different coastal environments. Monthly averages of the daily LEO (Littoral Environmental Observation) data...

  15. Recent marine archaeological investigations along the Saurashtra coast, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A; Sundaresh; Tripati, S.

    Recent marine archaeological explorations have brought to light data on the existence of ancient ports at Miyani and Kindari Creek (Mul Dwarka) on the Saurashtra coast. A large number and varieties of stone anchors have been documented at both sites...

  16. Benthic fauna of southwest and southeast coasts of India

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, K.S.; Sheba, P.; Balasubramanian, T.; Venugopal, P.; Sankaranarayanan, V.N.

    Benthos, sediments characteristics and organic matter content were studied along southwest and southeast coasts of India. Number of groups/species varied with the stations and also with the depths. Population density was very low in southeast coast...

  17. Heavy mineral occurrence off Hazira, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Vora, K.H.; Mislankar, P.G.; Gujar, A

    The occurrence of heavy mineral placers on the west coast of India are well known from Konkan and Malabar Coast. However, a geological and geophysical investigation (including echosounding and side scan sonar profiles and 7 samples) off Hazira...

  18. Dynamics and controls of urban heat sink and island phenomena in a desert city: Development of a local climate zone scheme using remotely-sensed inputs

    Science.gov (United States)

    Nassar, Ahmed K.; Blackburn, G. Alan; Whyatt, J. Duncan

    2016-09-01

    This study aims to determine the dynamics and controls of Surface Urban Heat Sinks (SUHS) and Surface Urban Heat Islands (SUHI) in desert cities, using Dubai as a case study. A Local Climate Zone (LCZ) schema was developed to subdivide the city into different zones based on similarities in land cover and urban geometry. Proximity to the Gulf Coast was also determined for each LCZ. The LCZs were then used to sample seasonal and daily imagery from the MODIS thermal sensor to determine Land Surface Temperature (LST) variations relative to desert sand. Canonical correlation techniques were then applied to determine which factors explained the variability between urban and desert LST. Our results indicate that the daytime SUHS effect is greatest during the summer months (typically ∼3.0 °C) with the strongest cooling effects in open high-rise zones of the city. In contrast, the night-time SUHI effect is greatest during the winter months (typically ∼3.5 °C) with the strongest warming effects in compact mid-rise zones of the city. Proximity to the Arabian Gulf had the largest influence on both SUHS and SUHI phenomena, promoting daytime cooling in the summer months and night-time warming in the winter months. However, other parameters associated with the urban environment such as building height had an influence on daytime cooling, with larger buildings promoting shade and variations in airflow. Likewise, other parameters such as sky view factor contributed to night-time warming, with higher temperatures associated with limited views of the sky.

  19. Application of multivariate statistical analyses in the interpretation of geochemical behaviour of uranium in phosphatic rocks in the Red Sea, Nile Valley and Western Desert, Egypt

    International Nuclear Information System (INIS)

    Factor and cluster analyses as well as the Pearson correlation coefficient have been applied to geochemical data obtained from phosphorite and phosphatic rocks of Duwi Formation exposed at the Red Sea coast, Nile Valley and Western Desert. Sixty-six samples from a total of 71 collected samples were analysed for SiO2, TiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, K2O, P2O5, Sr, U and Pb by XRF and their mineral constituents were determined by the use of XRD techniques. In addition, the natural radioactivity of the phosphatic samples due to their uranium, thorium and potassium contents was measured by gamma-spectrometry.The uranium content in the phosphate rocks with P2O5>15% (average of 106.6 ppm) is higher than in rocks with P2O52O5 and CaO, whereas it is not related to changes in SiO2, TiO2, Al2O3, Fe2O3, MgO, Na2O and K2O concentrations.Factor analysis and the Pearson correlation coefficient revealed that uranium behaves geochemically in different ways in the phosphatic sediments and phosphorites in the Red Sea, Nile Valley and Western Desert. In the Red Sea and Western Desert phosphorites, uranium occurs mainly in oxidized U6+ state where it seems to be fixed by the phosphate ion, forming secondary uranium phosphate minerals such as phosphuranylite.In the Nile Valley phosphorites, ionic substitution of Ca2+ by U4+ is the main controlling factor in the concentration of uranium in phosphate rocks. Moreover, fixation of U6+ by phosphate ion and adsorption of uranium on phosphate minerals play subordinate roles

  20. Parallel Study on Potential and Existing Geographical Distribution of Haloxylon Dominated Desert Vegetation in China

    Institute of Scientific and Technical Information of China (English)

    GUO Quanshui; WANG Chunling; TAN Deyuan; MA Chao; WANG Xiangfu; HAO Jianxi; HE Hongyan

    2006-01-01

    By applying ARC/INFO(NT version)of the GIS software package,we extracted the existing geographical distribution of Haloxylon dominated desert vegetation and produced a thematic map of geographical distribution of the existing Haloxylon dominated desert vegetation based on the newly published Vegetation Atlas of China;we defined the adaptive parameter range of geographical and climate of Haloxylon dominated desert vegetation to generate the potential geographical distribution map of Haloxylon dominated desert vegetation with the support of GREEN software.We then sliced and compared the existing and the potential distribution maps.The results show that the potential geographical distribution areas of Haloxylon ammodendron and Haloxylon persicum dominated desert vegetation accord with the existing distribution areas in the administration division,and the topographic types in both the distribution areas are similar.However,the borders of different directions of the potential H.ammodendron dominated desert vegetation distribution has surpassed 0.4°to 5.9°of the existing borders.The borders of different directions of the potential H. persicum dominated desert vegetation has surpassed 0.9°to 3.3°of the existing borders.In China,the existing geographical distributional area of H.ammodendron dominated desert vegetation accounts for 9.1% of the potential one in China and the proportion of the existing H.persicum dominated desert vegetation distribution area to the potential area is 34.1%.The result of comparison of the potential and the existing distribution area of Haloxylon dominated desert vegetation can provide important scientific basis for the recovery,reconstruction and introduction of Haloxylon dominated desert vegetation.