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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. Late Quaternary history of the Atacama Desert

    Science.gov (United States)

    Latorre, Claudio; Betancourt, Julio L.; Rech, Jason A.; Quade, Jay; Holmgren, Camille; Placzek, Christa; Maldonado, Antonio; Vuille, Mathias; Rylander, Kate A.

    2005-01-01

    Of the major subtropical deserts found in the Southern Hemisphere, the Atacama Desert is the driest. Throughout the Quaternary, the most pervasive climatic influence on the desert has been millennial-scale changes in the frequency and seasonality of the scant rainfall, and associated shifts in plant and animal distributions with elevation along the eastern margin of the desert. Over the past six years, we have mapped modern vegetation gradients and developed a number of palaeoenvironmental records, including vegetation histories from fossil rodent middens, groundwater levels from wetland (spring) deposits, and lake levels from shoreline evidence, along a 1200-kilometre transect (16–26°S) in the Atacama Desert. A strength of this palaeoclimate transect has been the ability to apply the same methodologies across broad elevational, latitudinal, climatic, vegetation and hydrological gradients. We are using this transect to reconstruct the histories of key components of the South American tropical (summer) and extratropical (winter) rainfall belts, precisely at those elevations where average annual rainfall wanes to zero. The focus has been on the transition from sparse, shrubby vegetation (known as the prepuna) into absolute desert, an expansive hyperarid terrain that extends from just above the coastal fog zone (approximately 800 metres) to more than 3500 metres in the most arid sectors in the southern Atacama.

  3. 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

  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. 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.

  6. Biotechnological Applications Derived from Microorganisms of the Atacama Desert

    OpenAIRE

    2014-01-01

    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 deriv...

  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. Intelligent Rover Execution for Detecting Life in the Atacama Desert

    Science.gov (United States)

    Baskaran, Vijayakumar; Muscettola, Nicola; Rijsman, David; Plaunt, Chris; Fry, Chuck

    2006-01-01

    On-board supervisory execution is crucial for the deployment of more capable and autonomous remote explorers. Planetary science is considering robotic explorers operating for long periods of time without ground supervision while interacting with a changing and often hostile environment. Effective and robust operations require on-board supervisory control with a high level of awareness of the principles of functioning of the environment and of the numerous internal subsystems that need to be coordinated. We describe an on-board rover executive that was deployed on a rover as past of the "Limits of Life in the Atacama Desert (LITA)" field campaign sponsored by the NASA ASTEP program. The executive was built using the Intelligent Distributed Execution Architecture (IDEA), an execution framework that uses model-based and plan-based supervisory control of its fundamental computational paradigm. We present the results of the third field experiment conducted in the Atacama desert (Chile) in August - October 2005.

  10. 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.

  11. Palaeoindian occupation of the Atacama Desert, northern Chile

    Science.gov (United States)

    Grosjean, Martin; Núñez, Lautaro; Cartajena, Isabel

    2005-10-01

    Palaeoindian occupation of the Atacama Desert in northern Chile has been found between 12 600 and 10 200 cal. yr BP. The new site at Salar Punta Negra (24°28S/60°53W/2976 m) includes about 1000 classifiable, mostly unifacial artefacts and, uniquely, three different diagnostic types of early projectile points. Two of the Lateglacial/early Holocene projectile types have wide distribution and are known from different geographical areas in South America: the Palaeoindian Fell fish-tail point mainly from the southern cone of South America, and the triangular Tuina points typical of the Puna of the south-central Andes in northern Chile and northwestern Argentina. In addition, we found a third type, a stemmed point typical for the Salar Punta Negra. Filling a large geographical gap of Fell occupation, the site at Salar Punta Negra provides evidence for generally much higher mobility and diversity of early cultures, and supports an Andean-Pacific route for early human exploration of South America to the south through the desert at intermediate altitudes. Contemporaneous high-amplitude climatic changes were fundamental preconditions to provide adequate environments and habitats, and to make Palaeoindian hunting-gathering occupation possible in the Atacama Desert.

  12. 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.

  13. ENSO effects on primary productivity in Southern Atacama desert

    OpenAIRE

    Squeo, F. A.; Tracol, Y.; López, D.; J. R. Gutiérrez; A. M. Cordova; Ehleringer, J. R.

    2006-01-01

    In the winter-rain southern Atacama Desert of the Coquimbo Region of Chile, El Niño - Southern Oscillation (ENSO) events modulate primary productivity. In this region, there are important changes in water availability between La Niña (dry) and El Niño (rainy) years. Using inter-annual comparisons of LANDSAT images from 30° to 31° S latitude, we observed changes in primary productivity between dry and rainy years at the regional level. There were also s...

  14. 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.

  15. Biotechnological Applications Derived from Microorganisms of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    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.

  16. Archipelago of endolithic microbial life in the hyper arid core of the Atacama Desert

    OpenAIRE

    Wierzchos, Jacek; Davila, Alfonso F.; Diruggiero, J.; Ríos, Asunción de los; Valea, Sergio; Cámara Gallego, Beatriz; Artieda, Octavio; Speranza, Mariela; Robinson, Courtney K; Souterre, T.; Souza Egipsy, Virginia; Ascaso, Carmen

    2012-01-01

    The hyper-arid core of the Atacama Desert is considered the driest and most life-limited place on Earth. As such, this desert is an ideal environment to study the survival and biological adaptation strategies of microorganisms to this extremely dry environment. The extreme aridity of the Atacama Desert allows us to address questions such as the potential for life in extraterrestrial environments such as the surface of Mars. Our results over the last six years of searching for micr...

  17. Perchlorate levels in soil and waters from the Atacama Desert.

    Science.gov (United States)

    Calderón, R; Palma, P; Parker, D; Molina, M; Godoy, F A; Escudey, M

    2014-02-01

    Perchlorate is an anion that originates as a contaminant in ground and surface waters. The presence of perchlorate in soil and water samples from northern Chile (Atacama Desert) was investigated by ion chromatography-electrospray mass spectrometry. Results indicated that perchlorate was found in five of seven soils (cultivated and uncultivated) ranging from 290 ± 1 to 2,565 ± 2 μg/kg. The greatest concentration of perchlorate was detected in Humberstone soil (2,565 ± 2 μg/kg) associated with nitrate deposits. Perchlorate levels in Chilean soils are greater than those reported for uncultivated soils in the United States. Perchlorate was also found in superficial running water ranging from 744 ± 0.01 to 1,480 ± 0.02 μg/L. Perchlorate water concentration is 30-60 times greater than levels established by the United States Environmental Protection Agency (24.5 μg/L) for drinking. PMID:24165784

  18. 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.

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

    OpenAIRE

    Diruggiero, J.; J. Wierzchos; C. K. Robinson; Souterre, T.; J. Ravel; Artieda, O.; V. Souza-Egipsy; C. Ascaso

    2013-01-01

    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 numb...

  20. Perennial stream discharge in the hyperarid Atacama Desert of northern Chile during the latest Pleistocene

    OpenAIRE

    Nester, Peter L.; Gayó, Eugenia; Latorre, Claudio; Jordan, Teresa E.; Blanco, Nicolás

    2007-01-01

    A large fraction of the vital groundwater in the Atacama Desert of northern Chile is likely composed of “fossil” or “ancient” reserves that receive little or no recharge in today's hyperarid climate. Here, we present evidence for latest Pleistocene perennial streamflow in canyons from the hyperarid core of the Atacama Desert in northern Chile. Fluvial terraces in the Pampa del Tamarugal (PdT) basin (21°S) contain widespread fossil wood, in situ roots, and well preserved leaf litter deposits i...

  1. 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

  2. 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...

  3. A 22,000-year record of monsoonal precipitation from northern Chile's Atacama Desert

    Science.gov (United States)

    Betancourt, J.L.; Latorre, C.; Rech, J.A.; Quade, Jay; Rylander, K.A.

    2000-01-01

    Fossil rodent middens and wetland deposits from the central Atacama Desert (22° to 24°S) indicate increasing summer precipitation, grass cover, and groundwater levels from 16.2 to 10.5 calendar kiloyears before present (ky B.P.). Higher elevation shrubs and summer-flowering grasses expanded downslope across what is now the edge of Absolute Desert, a broad expanse now largely devoid of rainfall and vegetation. Paradoxically, this pluvial period coincided with the summer insolation minimum and reduced adiabatic heating over the central Andes. Summer precipitation over the central Andes and central Atacama may depend on remote teleconnections between seasonal insolation forcing in both hemispheres, the Asian monsoon, and Pacific sea surface temperature gradients. A less pronounced episode of higher groundwater levels in the central Atacama from 8 to 3 ky B.P. conflicts with an extreme lowstand of Lake Titicaca, indicating either different climatic forcing or different response times and sensitivities to climatic change.

  4. Draft Genome Sequence of a Bacillus Bacterium from the Atacama Desert Wetlands Metagenome

    OpenAIRE

    Vilo, Claudia; Galetovic, Alexandra; Araya, Jorge E.; Gómez-Silva, Benito; Dong, Qunfeng

    2015-01-01

    We report here the draft genome sequence of a Bacillus bacterium isolated from the microflora of Nostoc colonies grown at the Andean wetlands in northern Chile. We consider this genome sequence to be a molecular tool for exploring microbial relationships and adaptation strategies to the prevailing extreme conditions at the Atacama Desert.

  5. Comparative analysis of the microbial communities inhabiting halite evaporites of the Atacama Desert

    OpenAIRE

    Ríos, Asunción de los; Valea, Sergio; Ascaso, Carmen; Davila, Alfonso F.; Kastovsky, Jan; McKay, Christopher P.; Wierzchos, Jacek

    2010-01-01

    Molecular biology and microscopy techniques were used to characterize the microbial communities inside halide evaporites from different parts of th Atacama Desert. Denaturing gradient fel eletrophoresis (DGGE) analysis revealed that the evaporite rocks harbor communities predominantly made up of cyanobacteria, along with heterotrophic bacteria an archae...

  6. Draft Genome Sequence of a Bacillus Bacterium from the Atacama Desert Wetlands Metagenome.

    Science.gov (United States)

    Vilo, Claudia; Galetovic, Alexandra; Araya, Jorge E; Gómez-Silva, Benito; Dong, Qunfeng

    2015-01-01

    We report here the draft genome sequence of a Bacillus bacterium isolated from the microflora of Nostoc colonies grown at the Andean wetlands in northern Chile. We consider this genome sequence to be a molecular tool for exploring microbial relationships and adaptation strategies to the prevailing extreme conditions at the Atacama Desert. PMID:26294639

  7. Discovery and microbial content of the driest site of the hyperarid Atacama Desert, Chile.

    Science.gov (United States)

    Azua-Bustos, Armando; Caro-Lara, Luis; Vicuña, Rafael

    2015-06-01

    The Atacama Desert is the driest and oldest desert on Earth. Eleven years ago, the Yungay region was established as the driest site of this hyperarid desert and also close to the dry limit for life on Earth. Since then, much has been published about the extraordinary characteristics of this site and its pertinence as a Mars analogue model. However, as a result of a more systematic search in the Atacama here, we describe a new site, María Elena South (MES), which is much drier than Yungay. The mean atmospheric relative humidity (RH) at MES was 17.3%, with the RH of its soils remaining at a constant 14% at the depth of 1 m, a value that matches the lowest RH measurements taken by the Mars Science Laboratory at Gale Crater. Remarkably, we found a number of viable bacterial species in the soil profile at MES using a combination of molecular dependent and independent methods, unveiling the presence of life in the driest place on the Atacama Desert reported to date. PMID:25545388

  8. VEGETATIVE GROWTH AND EARLY PRODUCTION OF SIX OLIVE CULTIVARS, IN SOUTHERN ATACAMA DESERT, CHILE

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    Freddy MORA

    2007-12-01

    Full Text Available Tree survival, early fruit production, vegetative growth and alternate bearing were examined in six different olive cultivars (Barnea, Biancolilla, Coratina, Empeltre, Koroneiki and Leccino under intensive agronomic conditions i southern Atacama Desert, in the Coquimbo Region of Chile. The cultivars were evaluated over four successive years and had a high survival rate (93% confi rming their potential for these dry-lands. Fruit production (recorded over the growing seasons 2002-2003, vegetative growth (2000-2003 and alternate bearing differed signifi cantly among cultivars. Olive selection in intensively managed planting at the southern part of the Atacama Desert depends on matching specifi c cultivars to sites on which they perform the best.

  9. Microbial Colonization of the Salt Deposits in the Driest Place of the Atacama Desert (Chile)

    Science.gov (United States)

    Stivaletta, Nunzia; Barbieri, Roberto; Billi, Daniela

    2012-06-01

    The Atacama Desert (Chile), one of the most arid places on Earth, shows hostile conditions for the development of epilithic microbial communities. In this study, we report the association of cyanobacteria ( Chroococcidiopsis sp.) and bacteria belonging to Actinobacteria and Beta-Gammaproteobacteria and Firmicutes phyla inhabiting the near surface of salt (halite) deposits of the Salar Grande Basin, Atacama Desert (Chile). The halite deposits were investigated by using optical, confocal and field emission scanning electron microscopes, whereas culture-independent molecular techniques, 16S rDNA clone library, alongside RFLP analysis and 16S rRNA gene sequencing were applied to investigate the bacterial diversity. These microbial communities are an example of life that has adapted to extreme environmental conditions caused by dryness, high irradiation, and metal concentrations. Their adaptation is, therefore, important in the investigation of the environmental conditions that might be expected for life outside of Earth.

  10. 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.

  11. Extreme environments as potential drivers of convergent evolution by exaptation: the Atacama Desert Coastal Range case

    OpenAIRE

    Azua-Bustos, Armando; González-Silva, Carlos; Arenas-Fajardo, Cristián; Vicuña, Rafael

    2012-01-01

    We have recently discovered a variety of unrelated phototrophic microorganisms (two microalgae and one cyanobacteria) in specialized terrestrial habitats at The Coastal Range of the Atacama Desert. Interestingly, morphological and molecular evidence suggest that these three species are all recent colonists that came from aquatic habitats. The first case is Cyanidiales inhabiting coastal caves. Cyanidiales are microalgae that are commonly found in warm acid springs, but have also been recently...

  12. VEGETATIVE GROWTH AND EARLY PRODUCTION OF SIX OLIVE CULTIVARS, IN SOUTHERN ATACAMA DESERT, CHILE

    OpenAIRE

    Freddy MORA; TAPIA, Francisco; Carlos Alberto; Elias Nunes

    2007-01-01

    Tree survival, early fruit production, vegetative growth and alternate bearing were examined in six different olive cultivars (Barnea, Biancolilla, Coratina, Empeltre, Koroneiki and Leccino) under intensive agronomic conditions i southern Atacama Desert, in the Coquimbo Region of Chile. The cultivars were evaluated over four successive years and had a high survival rate (93%) confi rming their potential for these dry-lands. Fruit production (recorded over the growing seasons 2002-2003), veget...

  13. Impact of Empire Expansion on Household Diet: The Inka in Northern Chile's Atacama Desert

    OpenAIRE

    Vinton, Sheila Dorsey; Perry, Linda; Reinhard, Karl J.; Santoro, Calogero M.; Teixeira-Santos, Isabel

    2009-01-01

    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...

  14. 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...

  15. Bacterial community structure in the hyperarid core of the Atacama Desert, Chile

    Science.gov (United States)

    Drees, Kevin P.; Neilson, Julia W.; Betancourt, Julio L.; Quade, Jay; Henderson, David A.; Pryor, Barry M.; Maier, Raina M.

    2006-01-01

    Soils from the hyperarid Atacama Desert of northern Chile were sampled along an east-west elevational transect (23.75 to 24.70 degrees S) through the driest sector to compare the relative structure of bacterial communities. Analysis of denaturing gradient gel electrophoresis (DGGE) profiles from each of the samples revealed that microbial communities from the extreme hyperarid core of the desert clustered separately from all of the remaining communities. Bands sequenced from DGGE profiles of two samples taken at a 22-month interval from this core region revealed the presence of similar populations dominated by bacteria from the Gemmatimonadetes and Planctomycetes phyla.

  16. Distribution and Diversity of Organic and Biological Signatures in Soils From the Atacama Desert

    Science.gov (United States)

    Sharma, Aditi

    2005-01-01

    The Atacama Desert is amongst the driest places on Earth. It is considered to be a suitable analog for the Martian surface in which to conduct studies of life and life detection. Soil samples were collected in June 2005 from the Atacama Desert and analyzed in the lab for amino acid content. HPLC was the primary tool used to analyze samples. The amino acids of interest are aspartic acid, serine, glutamic acid, glycine, and alanine. D and L isomers of each amino acid (except for glycine) were separated through HPLC. The purpose of this study is to find correlations between location of the sample collection sites and amino acid content as well as D/L isomer ratios in order to formulate theories of how different types of environments may affect the abundance and distribution of life forms. Initial analysis of data shows a general lack of or slight correlation between location and amino acid content. Some data appears to contradict the hypothesis that harsher environments would have lower amino acid content than less harsh environments. Further analysis of data is needed to come up with a more conclusive report of the distribution of amino acids in the Atacama Desert.

  17. Biodiversity of soil cyanobacteria in the hyper-arid Atacama Desert, Chile.

    Science.gov (United States)

    Patzelt, Dominik J; Hodač, Ladislav; Friedl, Thomas; Pietrasiak, Nicole; Johansen, Jeffrey R

    2014-08-01

    The cyanobacterial diversity of soils of the Atacama Desert (Chile) was investigated using 16S rRNA gene cloning/sequencing directly from soil samples and 16S rRNA gene sequencing from unialgal cultures. Within the hyper-arid Atacama Desert, one of the driest parts of the world, 10 sites with differing altitude and distance to the shore were sampled along a total air-line distance (from south to north) of ~1,100 km. Filamentous cyanobacteria belonging to Nostocophycideae and Synechococcophycideae were present. Oscillatoriophycideae exhibited the highest species richness among the subclasses of cyanobacteria, and included mostly filamentous species along with some coccoids (e.g., Chroococcidiopsis). Thirty species-level phylotypes could be recognized using a cut-off of 99% 16S rRNA sequence similarity within the 22 genera defined at 97% 16S rRNA sequence similarity. Eight of the 30 taxa could be detected by both clonal and culture sequences. Five taxa were observed only in cultures, whereas the cloning approach revealed 17 additional taxa, which might be in the collection but unsequenced, hard-to-cultivate, or entirely unculturable species using standard cultivation media. The Atacama Desert soils have a high diversity of phylotypes, among which are likely both new genera and new species awaiting characterization and description. PMID:26988453

  18. Mars Redox Chemistry: Atacama Desert Soils as a Terrestrial Analog

    Science.gov (United States)

    Quinn, R. C.; Grunthaner, F. J.; Taylor, C. L.; Zent, A. P.

    2003-01-01

    The motivation for this work is to perform quantitative site characterizations of soil chemical processes to allow further development and field validation of the Mars Oxidant Instrument (MOI). The MOI is an in situ survey instrument designed to establish the presence of reactive chemical species in the martian soil, dust, or atmosphere, and to provide detailed reaction model system measurements to enable comprehensive Earthbased study. Functioning as a survey instrument, MOI tests the broad range of hypotheses explaining the reactivity of the martian surface material that have been put forth since the Viking experiments. This work is currently being carried out under the NASA ASTEP funded AstroBioLab (Jeffery Bada, PI). A second objective is to use Atacama field and Viking data to perform comparative studies, with the goal of furthering the understanding of the formation mechanisms and properties of martian oxidants.

  19. Evolutionary lag times and recent origin of the biota of an ancient desert (Atacama-Sechura).

    Science.gov (United States)

    Guerrero, Pablo C; Rosas, Marcelo; Arroyo, Mary T K; Wiens, John J

    2013-07-01

    The assembly of regional biotas and organismal responses to anthropogenic climate change both depend on the capacity of organisms to adapt to novel ecological conditions. Here we demonstrate the concept of evolutionary lag time, the time between when a climatic regime or habitat develops in a region and when it is colonized by a given clade. We analyzed the time of colonization of four clades (three plant genera and one lizard genus) into the Atacama-Sechura Desert of South America, one of Earth's driest and oldest deserts. We reconstructed time-calibrated phylogenies for each clade and analyzed the timing of shifts in climatic distributions and biogeography and compared these estimates to independent geological estimates of the time of origin of these deserts. Chaetanthera and Malesherbia (plants) and Liolaemus (animal) invaded arid regions of the Atacama-Sechura Desert in the last 10 million years, some 20 million years after the initial onset of aridity in the region. There are also major lag times between when these clades colonized the region and when they invaded arid habitats within the region (typically 4-14 million years). Similarly, hyperarid climates developed ∼8 million years ago, but the most diverse plant clade in these habitats (Nolana) only colonized them ∼2 million years ago. Similar evolutionary lag times may occur in other organisms and habitats, but these results are important in suggesting that many lineages may require very long time scales to adapt to modern desertification and climatic change. PMID:23798420

  20. Atmospheric water uptake by an atacama desert shrub.

    Science.gov (United States)

    Mooney, H A; Gulmon, S L; Ehleringer, J; Rundel, P W

    1980-08-01

    Nolana mollis, a succulent-leaved shrub of the extreme coastal desert of Chile, has the capacity to condense water on its leaves out of unsaturated atmospheres, Metabolic energy would have to be expended to move this water either from the leaf surface directly to the mesophyll or, when dripped to the soil, from there into the roots. Because of the unusual aridity of its habitat and of the utilization of water-use-efficient metabolism by Nolana, at least during certain periods, such an energy expenditure could be effective. PMID:17821192

  1. Ignimbrite textural properties as determinants of endolithic colonization patterns from hyper-arid Atacama Desert.

    Science.gov (United States)

    Cámara, Beatriz; Suzuki, Shino; Nealson, Kenneth H; Wierzchos, Jacek; Ascaso, Carmen; Artieda, Octavio; de Los Ríos, Asunción

    2014-09-01

    This study explores the photosynthetic microbial colonization of rhyolitic ignimbrites in Lomas de Tilocalar, a hyper-arid region of the Atacama Desert, Chile. Colonization appeared in the form of a green layer a few millimeters beneath the ignimbrite surface. Some ignimbrite rocks revealed two distinct micromorphological areas of identical mineralogical and chemical composition but different textural properties. According to texture, colonization patterns varied in terms of the extension and depth of colonization. The diversity of photosynthetic microorganisms was assessed by denaturing gradient gel electrophoresis (DGGE) of the 23S rRNA gene and by generating clone libraries of the 16S rRNA gene. We observed a low diversity of photosynthetic microorganisms colonizing the ignimbrite microhabitat. Most rRNA gene sequences recovered greatly resembled those of Chroococcidiopsis hypolith clones from arid deserts. These results point to highly restrictive conditions of the hyper-arid Atacama Desert conditioning the diversity of cyanobacteria, and suggest that microbial colonization and composition patterns might be determined by the microscale physico-chemical properties of the ignimbrite rocks [Int Microbiol 2014; 17(4):235-247]. PMID:26421739

  2. 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

  3. 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.

  4. Extreme environments as potential drivers of convergent evolution by exaptation: the Atacama Desert Coastal Range case.

    Directory of Open Access Journals (Sweden)

    ArmandoAzua-Bustos

    2012-12-01

    Full Text Available We have recently discovered a variety of unrelated phototrophic microorganisms (two microalgae and one cyanobacteria in specialized terrestrial habitats at The Coastal Range of the Atacama Desert. Interestingly, morphological and molecular evidence suggest that these three species are all recent colonists that came from aquatic habitats. The first case is Cyanidiales inhabiting coastal caves. Cyanidiales are microalgae that are commonly found in warm acid springs, but have also been recently discovered as cave flora in Italy. The case is Dunaliella biofilms colonizing spider webs in coastal caves; Dunaliella are microalgae typically found in hypersaline habitats. The third case is Chroococcidiopsis, a genus of Cyanobacteria commonly found in deserts around the world that has also been described in warm springs. Thus, we show that the traits found in the closest ancestors of the aforementioned species (which inhabited other unrelated extreme environments seem to be now useful for the described species in their current subaerial habitats, and may likely correspond to cases of exaptations. Altogether, the Coastal Range of the Atacama Desert may be considered as a place where key steps on the colonization of land by phototrophic organisms seem to be being repeated by convergent evolution of extant microalgae and Cyanobacteria.

  5. Com sobreviuen els microorganismes fotosintètics al desert d'Atacama?

    OpenAIRE

    Roldán, Mònica

    2014-01-01

    Amb un índex d'aridesa del 0,0005, el desert d'Atacama (Xile) és el lloc més sec de la Terra. Investigadors del Servei de Microscòpia de la UAB i del Museu Nacional de Ciències Naturals de Madrid han publicat un estudi en el qual es demostren les diferents estratègies que els microorganismes fotosintètics han desenvolupat en aquest ambient d'extrema sequedat per sobreviure a l'interior de les halites, roques compostes de sal comuna (NaCl), on han de fer front a condicions de salinitat extrema...

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

    Science.gov (United States)

    Collado, Gonzalo A

    2015-01-01

    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. PMID:25781755

  7. 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.

  8. Bacterial Diversity in Microbial Mats and Sediments from the Atacama Desert.

    Science.gov (United States)

    Rasuk, Maria Cecilia; Fernández, Ana Beatriz; Kurth, Daniel; Contreras, Manuel; Novoa, Fernando; Poiré, Daniel; Farías, María Eugenia

    2016-01-01

    The Atacama Desert has extreme environmental conditions that allow the development of unique microbial communities. The present paper reports the bacterial diversity of microbial mats and sediments and its mineralogical components. Some physicochemical conditions of the water surrounding these ecosystems have also been studied trying to determine their influence on the diversity of these communities. In that way, mats and sediments distributed among different hypersaline lakes located in salt flats of the Atacama Desert were subjected to massive parallel sequencing of the V4 region of the 16S rRNA genes of Bacteria. A higher diversity in sediment than in mat samples have been found. Lakes that harbor microbial mats have higher salinity than lakes where mats are absent. Proteobacteria and/or Bacteroidetes are the major phyla represented in all samples. An interesting item is the finding of a low proportion or absence of Cyanobacteria sequences in the ecosystems studied, suggesting the possibility that other groups may be playing an essential role as primary producers in these extreme environments. Additionally, the large proportion of 16S rRNA gene sequences that could not be classified at the level of phylum indicates potential new phyla present in these ecosystems. PMID:26224164

  9. 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.

  10. 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.

  11. 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.

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

    Czech Academy of Sciences Publication Activity Database

    Wierzchos, J.; DiRuggiero, J.; Vítek, Petr; Artieda, O.; Souza-Egipsy, V.; Škaloud, P.; Tisza, M.; Davilla, A. F.; Vilchez, C.; Garbayo, I.; Ascaso, C.

    2015-01-01

    Roč. 6, č. 934 (2015), s. 1-17. ISSN 1664-302X R&D Projects: GA MŠk EE2.3.20.0246 Institutional support: RVO:67179843 Keywords : Atacama Desert * carotenoids * endolithic chlorophototrophs * extreme environment * gypsum * scytonemin Subject RIV: DD - Geochemistry Impact factor: 3.989, year: 2014

  14. Isotopic evidence for the source of Ca and S in soil gypsum, anhydrite and calcite in the Atacama Desert, Chile

    Science.gov (United States)

    Rech, Jason A.; Quade, Jay; Hart, William S.

    The origin of pedogenic salts in the Atacama Desert has long been debated. Possible salt sources include in situ weathering at the soil site, local sources such as aerosols from the adjacent Pacific Ocean or salt-encrusted playas (salars), and extra-local atmospheric dust. To identify the origin of Ca and S in Atacama soil salts, we determined δ 34S and 87Sr/ 86Sr values of soil gypsum/anhydrite and 87Sr/ 86Sr values of soil calcite along three east-west trending transects. Our results demonstrate the strong influence of marine aerosols on soil gypsum/anhydrite development in areas where marine fog penetrates inland. Results from an east-west transect located along a breach in the Coastal Cordillera show that most soils within 90 km of the coast, and below 1300 m in elevation, are influenced by marine aerosols and that soils within 50 km, and below 800 m in elevation, receive >50% of Ca and S from marine aerosols (δ 34S values > 14‰ and 87Sr/ 86Sr values >0.7083). In areas where the Coastal Cordillera is >1200 m in elevation, however, coastal fog cannot penetrate inland and the contribution of marine aerosols to soils is greatly reduced. Most pedogenic salts from inland soils have δ 34S values between +5.0 to +8.0‰ and 87Sr/ 86Sr ratios between 0.7070 and 0.7076. These values are similar to average δ 34S and 87Sr/ 86Sr values of salts from local streams, lakes, and salars (+5.4 ±2‰ δ 34S and 0.70749 ± 0.00045 87Sr/ 86Sr) in the Andes and Atacama, suggesting extensive eolian reworking of salar salts onto the surrounding landscape. Ultimately, salar salts are precipitated from evaporated ground water, which has acquired its dissolved solutes from water-rock interactions (both high and low-temperature) along flowpaths from recharge areas in the Andes. Therefore, the main source for Ca and S in gypsum/anhydrite in non-coastal soils is indirect and involves bedrock alteration, not surficially on the hyperarid landscape, but in the subsurface by ground water

  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. Dry Acid Deposition and Accumulation on the Surface of Mars and in the Atacama Desert, Chile

    Science.gov (United States)

    Quinn, R. C.; Zent, A. P.; Ehrenfruend, P.; Taylor, C. L.; McKay, C. P.; Garry, J. R. C.

    2005-01-01

    It has been discovered recently that soils from certain regions of the Chilean Atacama Desert have some characteristics that are similar to the surface materials tested by the Viking Landers. Navarro-Gonzalez et al. demonstrated that the quantity and diversity of heterotrophic bacteria increase as a function of local water availability in the Atacama, and that for some soil samples collected in the driest regions, no culturable bacteria could be isolated. Additionally, Navarro-Gonzalez et al. reported that pyrolysis-GCMS analysis of soils collected from these regions revealed extremely low levels of organic matter. Although the mechanism resulting in the low level of organics in these regions was not established by Navarro-Gonzalez, the condition of organic-depleted, near-sterile soil offers an interesting Earth analog of the martian surface material, as the Viking Gas Exchange (GEx) experiment and Labeled Release (LR) experiment were unable to demonstrate the presence of culturable bacteria, and the Viking pyrolysis- GCMS was unable to detect organic compounds.

  19. Chaxapeptin, a Lasso Peptide from Extremotolerant Streptomyces leeuwenhoekii Strain C58 from the Hyperarid Atacama Desert.

    Science.gov (United States)

    Elsayed, Somayah S; Trusch, Franziska; Deng, Hai; Raab, Andrea; Prokes, Ivan; Busarakam, Kanungnid; Asenjo, Juan A; Andrews, Barbara A; van West, Pieter; Bull, Alan T; Goodfellow, Michael; Yi, Yu; Ebel, Rainer; Jaspars, Marcel; Rateb, Mostafa E

    2015-10-16

    Lasso peptides are ribosomally synthesized and post-translationally modified peptides (RiPPs) that possess a unique "lariat knot" structural motif. Genome mining-targeted discovery of new natural products from microbes obtained from extreme environments has led to the identification of a gene cluster directing the biosynthesis of a new lasso peptide, designated as chaxapeptin 1, in the genome of Streptomyces leeuwenhoekii strain C58 isolated from the Atacama Desert. Subsequently, 1 was isolated and characterized using high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance methods. The lasso nature of 1 was confirmed by calculating its nuclear Overhauser effect restraint-based solution structure. Chaxapeptin 1 displayed a significant inhibitory activity in a cell invasion assay with human lung cancer cell line A549. PMID:26402731

  20. Miniaturized Raman instrumentation detects carotenoids in Mars-analogue rocks from the Mojave and Atacama deserts.

    Science.gov (United States)

    Vítek, P; Jehlička, J; Edwards, H G M; Hutchinson, I; Ascaso, C; Wierzchos, J

    2014-12-13

    This study is primarily focused on proving the potential of miniaturized Raman systems to detect any biomolecular and mineral signal in natural geobiological samples that are relevant for future application of the technique within astrobiologically aimed missions on Mars. A series of evaporites of varying composition and origin from two extremely dry deserts were studied, namely Atacama and Mojave. The samples represent both dry evaporitic deposits and recent evaporitic efflorescences from hypersaline brines. The samples comprise halite and different types of sulfates and carbonates. The samples were analysed in two different ways: (i) directly as untreated rocks and (ii) as homogenized powders. Two excitation wavelengths of miniaturized Raman spectrometers were compared: 532 and 785 nm. The potential to detect carotenoids as biomarkers on Mars compared with the potential detection of carbonaceous matter using miniaturized instrumentation is discussed. PMID:25368344

  1. Distribution of prokaryotic genetic diversity in athalassohaline lakes of the Atacama Desert, Northern Chile.

    Science.gov (United States)

    Demergasso, Cecilia; Casamayor, Emilio O; Chong, Guillermo; Galleguillos, Pedro; Escudero, Lorena; Pedrós-Alió, Carlos

    2004-04-01

    Athalassohaline lakes are inland saline aquatic environments with ionic proportions quite different from the dissolved salts in seawater. Prokaryotes inhabiting athalassohaline environments are poorly known and very few of such places have been surveyed for microbial diversity studies around the world. We analyzed the planktonic bacterial and archaeal assemblages inhabiting several of these evaporitic basins in a remote and vast area in northern Chile by PCR-denaturing gradient gel electrophoresis (DGGE) and sequencing of 16S rRNA gene fragments. Most systems were springs and athalassohaline ponds in different saltflats of the Atacama Desert region, including Salar de Llamará (in the Central Depression), Salar de Atacama (in the Pre-Andean Depression) and Salar de Ascotán (in the Altiplano). Overall, we analyzed more than 25 samples from 19 different environments with strong gradients of altitude, qualitative ionic compositions and UV influence. Between 4 and 25 well-defined DGGE bands were detected for Bacteria in each sample, whereas Archaea ranged between 1 and 5. Predominant DGGE bands (defined by intensity and frequency of appearance) were excised from the gel and sequenced. Bacterial assemblages were dominated by the Cytophaga-Flavobacterium-Bacteroides (CFB) phylum and a few Proteobacteria. There was a tendency for increasing contribution of CFB with higher salinities and altitude. Thus, CFB accounted for the major fraction of band intensity in the Ascotán samples and for lower percentages in Atacama and Llamará. When the distribution of particular CFB sequences was examined, there were several relatives of Psychroflexus torquis substituting each other as salinity changed in Ascotán. Another set of CFB sequences, very distantly related to Cytophaga marinovorus, was abundant in both Llamará and Atacama at salinities lower than 7%. Archaeal assemblages were dominated by uncultured haloarchaea distantly related to cultured strains mostly obtained from

  2. Use of a novel rover-mounted fluorescence imager and fluorescent probes to detect biological material in the Atacama Desert in daylight

    OpenAIRE

    Weinstein, S; Pane, D.; Warren-Rhodes, K.; Cockell, C; Ernst, L. A.; Minkley, E.; Fisher, G.; Emani, S.; Wettergreen, D. S.; Wagner, M.; Cabrol, J. N.; Waggoner, A S

    2005-01-01

    We deployed our fluorescence imaging system which detects fluorescence signals from sparse microorganisms and biofilms on Carnegie Mellon University’s autonomous rover Zoë. The results of the 2004 Atacama Desert field season, in Chile, are discussed.

  3. 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

  4. 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

  5. Validation of a Clostridium Endospore Viability Assay and Analysis of Greenland Ices and Atacama Desert Soils▿ †

    OpenAIRE

    Yang, Wan-Wan; Ponce, Adrian

    2011-01-01

    A microscopy-based endospore viability assay (micro-EVA) capable of enumerating germinable Clostridium endospores (GCEs) in less than 30 min has been validated and employed to determine GCE concentrations in Greenland ices and Atacama Desert soils. Inoculation onto agarose doped with Tb3+ and d-alanine triggers Clostridium spore germination and the concomitant release of ∼108 molecules of dipicolinic acid (DPA) per endospore, which, under pulsed UV excitation, enables enumeration of resultant...

  6. Evaporation in the Atacama Desert: An empirical study of spatio-temporal variations and their causes

    Science.gov (United States)

    Houston, John

    2006-11-01

    SummaryThe Atacama Desert is hyper-arid, and areas where adequate moisture exists for evaporation are spatially highly restricted. Nevertheless, water resources exist and their evaluation requires knowledge of this elusive but important component of the hydrological cycle. Evaporation may occur in four typical areas: rivers and associated riparian zones, localized springs, large playas and extensive areas of bare soil after infrequent precipitation events. Transpiration is locally possible where moisture is sufficiently close to the surface to allow phreatophytes or scarce grass cover to grow, but virtually no information is available for quantification. Pan evaporation data from 11 stations for the period 1977-1991 is analyzed and complemented by analysis of an evaporation study conducted in the Salar de Atacama during 1987/1988. The results show that pan evaporation, and hence maximum potential evaporation may be considered largely a function of maximum temperature and elevation as well as density of the evaporating fluid. Actual evaporation is limited by available moisture and diminishes rapidly as the level of soil moisture saturation drops below the soil surface, extinguishing at ca. 2 m depth. Evaporation is greatest during the summer, but at higher elevations convective cloudiness develops during January and February reducing evaporating rates at a time when significant precipitation may occur. Inter-annual variations in pan evaporation are considerable and weakly correlated with ENSO, but variations in actual evaporation are damped by comparison. Regression equations are developed which have widespread applicability and may be used to estimate evaporation in areas where no site-specific data exists.

  7. 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

  8. 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

  9. 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

  10. 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

    2008-05-01

    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).

  11. Life at the hyperarid margin: novel bacterial diversity in arid soils of the Atacama Desert, Chile

    Science.gov (United States)

    Neilson, Julia W.; Quade, Jay; Ortiz, Marianyoly; Nelson, William M.; Legatzki, Antje; Tian, Fei; LaComb, Michelle; Betancourt, Julio L.; Wing, Rod A.; Soderlund, Carol A.; Maier, Raina M.

    2012-01-01

    Nearly half the earth's surface is occupied by dryland ecosystems, regions susceptible to reduced states of biological productivity caused by climate fluctuations. Of these regions, arid zones located at the interface between vegetated semiarid regions and biologically unproductive hyperarid zones are considered most vulnerable. The objective of this study was to conduct a deep diversity analysis of bacterial communities in unvegetated arid soils of the Atacama Desert, to characterize community structure and infer the functional potential of these communities based on observed phylogenetic associations. A 454-pyrotag analysis was conducted of three unvegetated arid sites located at the hyperarid-arid margin. The analysis revealed communities with unique bacterial diversity marked by high abundances of novel Actinobacteria and Chloroflexi and low levels of Acidobacteria and Proteobacteria, phyla that are dominant in many biomes. A 16S rRNA gene library of one site revealed the presence of clones with phylogenetic associations to chemoautotrophic taxa able to obtain energy through oxidation of nitrite, carbon monoxide, iron, or sulfur. Thus, soils at the hyperarid margin were found to harbor a wealth of novel bacteria and to support potentially viable communities with phylogenetic associations to non-phototrophic primary producers and bacteria capable of biogeochemical cycling.

  12. Fluorescent fingerprints of endolithic phototrophic cyanobacteria living within halite rocks in the Atacama Desert.

    Science.gov (United States)

    Roldán, M; Ascaso, C; Wierzchos, J

    2014-05-01

    Halite deposits from the hyperarid zone of the Atacama Desert reveal the presence of endolithic microbial colonization dominated by cyanobacteria associated with heterotrophic bacteria and archaea. Using the λ-scan confocal laser scanning microscopy (CLSM) option, this study examines the autofluorescence emission spectra produced by single cyanobacterial cells found inside halite rocks and by their photosynthetic pigments. Photosynthetic pigments could be identified according to the shapes of the emission spectra and wavelengths of fluorescence peaks. According to their fluorescence fingerprints, three groups of cyanobacterial cells were identified within this natural extreme microhabitat: (i) cells producing a single fluorescence peak corresponding to the emission range of phycobiliproteins and chlorophyll a, (ii) cells producing two fluorescence peaks within the red and green signal ranges, and (iii) cells emitting only low-intensity fluorescence within the nonspecific green fluorescence signal range. Photosynthetic pigment fingerprints emerged as indicators of the preservation state or viability of the cells. These observations were supported by a cell plasma membrane integrity test based on Sytox Green DNA staining and by transmission electron microscopy ultrastructural observations of cyanobacterial cells. PMID:24610843

  13. 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).

  14. Molecular analysis of a 11 700-year-old rodent midden from the Atacama Desert, Chile

    Science.gov (United States)

    Kuch, M.; Rohland, N.; Betancourt, J.L.; Latorre, C.; Steppan, S.; Poinar, H.N.

    2002-01-01

    DNA was extracted from an 11 700-year-old rodent midden from the Atacama Desert, Chile and the chloroplast and animal mitochondrial DNA (mtDNA) gene sequences were analysed to investigate the floral environment surrounding the midden, and the identity of the midden agent. The plant sequences, together with the macroscopic identifications, suggest the presence of 13 plant families and three orders that no longer exist today at the midden locality, and thus point to a much more diverse and humid climate 11 700 years ago. The mtDNA sequences suggest the presence of at least four different vertebrates, which have been putatively identified as a camelid (vicuna), two rodents (Phyllotis and Abrocoma), and a cardinal bird (Passeriformes). To identify the midden agent, DNA was extracted from pooled faecal pellets, three small overlapping fragments of the mitochondrial cytochrome b gene were amplified and multiple clones were sequenced. These results were analysed along with complete cytochrome b sequences for several modern Phyllotis species to place the midden sequence phylogenetically. The results identified the midden agent as belonging to an ancestral P. limatus. Today, P. limatus is not found at the midden locality but it can be found 100 km to the north, indicating at least a small range shift. The more extensive sampling of modern Phyllotis reinforces the suggestion that P. limatus is recently derived from a peripheral isolate.

  15. Evidence for nonallopatric speciation among closely related sympatric Heliotropium species in the Atacama Desert.

    Science.gov (United States)

    Luebert, Federico; Jacobs, Pit; Hilger, Hartmut H; Muller, Ludo A H

    2014-02-01

    The genetic structure of populations of closely related, sympatric species may hold the signature of the geographical mode of the speciation process. In fully allopatric speciation, it is expected that genetic differentiation between species is homogeneously distributed across the genome. In nonallopatric speciation, the genomes may remain undifferentiated to a large extent. In this article, we analyzed the genetic structure of five sympatric species from the plant genus Heliotropium in the Atacama Desert. We used amplified fragment length polymorphisms (AFLPs) to characterize the genetic structure of these species and evaluate their genetic differentiation as well as the number of loci subject to positive selection using divergence outlier analysis (DOA). The five species form distinguishable groups in the genetic space, with zones of overlap, indicating that they are possibly not completely isolated. Among-species differentiation accounts for 35% of the total genetic differentiation (F ST = 0.35), and F ST between species pairs is positively correlated with phylogenetic distance. DOA suggests that few loci are subject to positive selection, which is in line with a scenario of nonallopatric speciation. These results support the idea that sympatric species of Heliotropium sect. Cochranea are under an ongoing speciation process, characterized by a fluctuation of population ranges in response to pulses of arid and humid periods during Quaternary times. PMID:24558582

  16. 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.

  17. 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.

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

    Science.gov (United States)

    Vinton, Sheila Dorsey; Perry, Linda; Reinhard, Karl J; Santoro, Calogero M; Teixeira-Santos, Isabel

    2009-01-01

    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. PMID:19956668

  19. Fluorescent Fingerprints of Endolithic Phototrophic Cyanobacteria Living within Halite Rocks in the Atacama Desert

    Science.gov (United States)

    Ascaso, C.; Wierzchos, J.

    2014-01-01

    Halite deposits from the hyperarid zone of the Atacama Desert reveal the presence of endolithic microbial colonization dominated by cyanobacteria associated with heterotrophic bacteria and archaea. Using the λ-scan confocal laser scanning microscopy (CLSM) option, this study examines the autofluorescence emission spectra produced by single cyanobacterial cells found inside halite rocks and by their photosynthetic pigments. Photosynthetic pigments could be identified according to the shapes of the emission spectra and wavelengths of fluorescence peaks. According to their fluorescence fingerprints, three groups of cyanobacterial cells were identified within this natural extreme microhabitat: (i) cells producing a single fluorescence peak corresponding to the emission range of phycobiliproteins and chlorophyll a, (ii) cells producing two fluorescence peaks within the red and green signal ranges, and (iii) cells emitting only low-intensity fluorescence within the nonspecific green fluorescence signal range. Photosynthetic pigment fingerprints emerged as indicators of the preservation state or viability of the cells. These observations were supported by a cell plasma membrane integrity test based on Sytox Green DNA staining and by transmission electron microscopy ultrastructural observations of cyanobacterial cells. PMID:24610843

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Isotopic evidence for divergent diets and mobility patterns in the Atacama Desert, northern Chile, during the Late Intermediate Period (AD 900-1450).

    Science.gov (United States)

    Santana-Sagredo, Francisca; Lee-Thorp, Julia A; Schulting, Rick; Uribe, Mauricio

    2015-03-01

    The decline of the Tiwanaku state saw the emergence of two new cultures-Pica-Tarapacá and Atacama-during the Late Intermediate Period in northern Chile. Archeological evidence suggests that both groups practised maize agriculture and pastoralism, but that their interaction zones differed significantly. Marine resources are common at Pica-Tarapacá sites, even those far from coast, while Atacama sites in the desert oases and precordilleran area seem to have directed their networks towards the highlands. Here we apply stable carbon, nitrogen, and oxygen isotope analysis on human bone and enamel to test dietary patterns and residential mobility at two sites, Pica 8 and Quitor 6, representing the Pica-Tarapacá and Atacama cultures, respectively. Our results show that diet at the two sites indeed differed: significant but variable consumption of marine resources and maize is indicated at Pica 8, despite being an inland site, while diet at Quitor 6 was based mainly on terrestrial resources. The use of seabird guano and llama dung as fertilizers and extreme aridity may have contributed to the high nitrogen isotope values observed in Pica 8 humans. The δ(18) O values in Pica 8 individuals are generally lower than for Quitor in spite of its greater distance from the Andes. All three isotopes suggest the presence of at least five nonlocals in the 30 measured at Pica 8. This evidence for human mobility is consistent with the high levels of trade and interaction observed in the archeological record, and begins to quantify the degree of movement of specific individuals. PMID:25385676

  5. Room temperature 57Fe Moessbauer spectroscopy of ordinary chondrites from the Atacama Desert (Chile): constraining the weathering processes on desert meteorites

    International Nuclear Information System (INIS)

    We report the results of a study on the weathering products of 21 meteorites found in the Atacama Desert (Chile) using room temperature 57Fe Moessbauer spectroscopy (MS). The meteorites are weathered ordinary chondrites (OCs) with unknown terrestrial ages and include the three chemical groups (H, L, and LL). We obtained the percentage of all the Fe-bearing phases for the primary minerals: olivine, pyroxene, troilite and Fe-Ni metal, and for the ferric alteration products (composed of the paramagnetic Fe3+ component and the magnetically ordered Fe3+ components) which gives the percentage of oxidation of the samples. From the Moessbauer absorption areas of these oxides, the terrestrial oxidation of the Atacama OC was found in the range from ∼5% to ∼60%. The amount of silicates as well as the opaques decreases at a constant rate with increasing oxidation level.

  6. Thermal biology of the fossorial rodent Ctenomys fulvus from the Atacama desert, northern Chile.

    Science.gov (United States)

    Cortés; Miranda; Rosenmann; Rau

    2000-12-01

    The Andean tuco-tuco, Ctenomys fulvus (Rodentia: Ctenomyidae) inhabits one of the most arid regions of the world, the Salar de Atacama, Northeast of Antofagasta, Chile (23 degrees 17'06"S, 68 degrees 05'43"W; 2.240 m.a.s.l). We found that a stable microclimate in burrows, a low evaporative water loss (EWL), and a diet of roots (59% water content) are the main factors that permit the survival of this fossorial species in harsh desert conditions. Large circadian variation in T(a) was observed above ground. Daily DeltaT(a) (T(a) max - T(a) min) = 37.9+/-0.2 degrees C in summer and in winter. In contrast, circadian variation of T(a) inside the burrows was only 5.8+/-0.5 degrees C in the same seasons. Relative humidity (RH) was 1.9-3.1% during the day, increasing to maximum values of 27% at night and early morning. Inside the burrows RH was higher and quite stable, ranging between 53.1 and 65%, independent of the time of day and season. EWL, measured between 10 and 25 degrees C, was low (1.26 mg/g h), and a moderate increase of 13-20% was observed at higher temperatures. The low EWL may prevent dehydration. However, because of the low heat loss capability, animals became hyperthermic (0.8-1.6 degrees C) in dry air at T(a)=30-35 degrees C. As T(a) during afternoon normally exceeded 35 degrees C, the microclimate of burrows provided the only way to avoid the lethal effects of hyperthermia. PMID:10880865

  7. Alto Patache fog oasis in the Atacama Desert: Geographical basis for a sustainable development program

    Science.gov (United States)

    Calderón, M.; Cereceda, P.; Larrain, H.; Osses, P.; Pérez, L.; Ibáñez, M.

    2010-07-01

    Alto Patache coastal fog oasis is a protected area located south of Iquique, Northern Chile, being presently in charge of the Atacama Desert Center (ADC) research group of the Pontificia Universidad Católica de Chile, since 1997. On 2007, the Chilean Government bestowed a piece of land stretch covering 1,114 hectares to ADC scientific group for scientific research, ecosystem protection and environmental education. This oasis has been recently studied from different points of view: climate, biogeography, fog collection, geomorphology, soil survey and land use planning, plant distribution, conservation and archaeology. During 2009, a study of the geographical basis to elaborate a general management plan was undertaken to collect information to fulfill our planned out objectives. Through this study, georreferenciated strategic information was compiled to evaluate future actions conducting to a sustainable development within the protected area. This information was translated into thematic maps showing the spatial distribution of variables like: climate, geology, geomorphology, soils, vegetation, fauna, archaeological sites and management zones. The methodology used is the analysis of satellite imagery, using GPS by creating a cartographic Data Base incorporated in GIS. Results show that the area starts at the littoral plain, ranging from 500 m to 2.000 m, being continued in parts by a piedmont intercepted by a very abrupt mega-cliff, or hectares of climbing sand dunes leading to a short high plateau limited by a soft hilly area to the East. Two soil types are characteristic: Entisols (Torriorthent) covering the coastal beach sediments, and Aridisols along the cliff and adjacent hills. Vegetation consists not only of a very rich lichen cover, but also of endangered vascular species associations constituting a very fragile sub-tropical coastal desert community, such as Eulychnia, Cumulopuntia, Eriosyce cacti, and Lycium - Nolana- Ephedra communities. Fog oasis

  8. Biodegradation of Tributyltin (TBT) by Extremophile Bacteria from Atacama Desert and Speciation of Tin By-products.

    Science.gov (United States)

    Yáñez, Jorge; Riffo, Paula; Santander, Paola; Mansilla, Héctor D; Mondaca, María Angélica; Campos, Víctor; Amarasiriwardena, Dulasiri

    2015-07-01

    Biodegradation of tributyltin (TBT) by four tin resistant Gram negative bacteria isolated from extremely contaminated river sediments in the Atacama Desert in Chile was studied. Moraxella osloensis showed the greatest resistance and degradation capability of TBT, producing less toxic by-products, such as dibutyltin (DBT) and inorganic tin. In 7 days, approximately 80 % of TBT degradation was achieved, generating close to 20 % of DBT as degradation product. The degradation rate constant (k) was 0.022 [day(-1)] and TBT half-life (t1/2) in culture was 4.3 days. Debutylation is stated a probable mechanism of TBT degradation. PMID:25975619

  9. Complete genome sequence of Microbacterium sp. CGR1, bacterium tolerant to wide abiotic conditions isolated from the Atacama Desert.

    Science.gov (United States)

    Mandakovic, Dinka; Cabrera, Pablo; Pulgar, Rodrigo; Maldonado, Jonathan; Aravena, Pamela; Latorre, Mauricio; Cambiazo, Verónica; González, Mauricio

    2015-12-20

    Microbacterium sp. CGR1 (RGM2230) is an isolate from the Atacama Desert that displays a wide pH, salinity and temperature tolerance. This strain exhibits riboflavin overproducer features and traits for developing an environmental arsenic biosensor. Here, we report the complete genome sequence of this strain, which represents the first genome of the genus Microbacterium sequenced and assembled in a single contig. The genome contains 3,634,864bp, 3299 protein-coding genes, 45 tRNAs, six copies of 5S-16S-23S rRNA and a high genome average GC-content of 68.04%. PMID:26521698

  10. The Tale of Hyper-arid Pedogenesis-Two Comparing Sites in the Atacama Desert, Chile

    Science.gov (United States)

    Wang, F.; Seo, J.; Bowen, B.; Ochoa, R.; Michalski, G.

    2010-12-01

    The hyper-arid core of the Atacama Desert, Chile contains Mars-like soils that have extremely low levels of microorganisms and organic materials but high concentrations of unusual salts, providing an excellent terrestrial analog to Martian surface. This study presents two comparing sites: a 4 m-high incised paleosol at Chug-Chug field site and a 2 m-deep mining trench in the Baquedano region, to investigate pedogenic development in hyper-arid regions by performing geochemical and stable oxygen isotopic analysis on the whole set of profile samples collected at 4~5 cm vertical resolution. Geochemical data shows that both of these two sites are rich in chloride, nitrate and sulfate anions as well as sodium and calcium cations with molar ratios of Ca2+/SO42- and Na+/(NO3-+Cl-) close to 1, suggesting the common minerals are soda niter (NaNO3), halite (NaCl), gypsum (CaSO42H2O) and anhydrite (CaSO4). Significant Δ17O anomalies (17.0-20.4‰) are both observed in the NO3- salts from the two sites, indicating nitrate is mainly originated from the photochemically produced nitric acid in the atmosphere and pedogenic development may be dominated by the simple accumulation of atmospheric derived particles in a layer like fashion due to hyper-aridity. The average NO3-/Cl- molar ratio of 0.89 in the Baquedano site is lower than that of 1.13 in the Chug-Chug site, probably because the Baquedano site is closer to the ocean and submicron aerosols in clean marine air have lower NO3-/Cl- ratio than in preanthroprogenic continental aerosols. However, small aqueous activities like decadal rainfall and daily fog events may punctuate the accumulation and have a large influence on the evolution of saline minerals. For example, the most soluble ions, NO3-, Cl-, and Na+, are mostly conservative with depth, but their high concentration peaks are both observed at a depth of ~2 m in both sites, which can be due to the accumulation of atmospheric salts without leaching in an extremely dry

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

    Science.gov (United States)

    Gonçalves, Vívian N; Cantrell, Charles L; Wedge, David E; Ferreira, Mariana C; Soares, Marco Aurélio; Jacob, Melissa R; Oliveira, Fabio S; Galante, Douglas; Rodrigues, Fabio; Alves, Tânia M A; Zani, Carlos L; Junior, Policarpo A S; Murta, Silvane; Romanha, Alvaro J; Barbosa, Emerson C; Kroon, Erna G; Oliveira, Jaquelline G; Gomez-Silva, Benito; Galetovic, Alexandra; Rosa, Carlos A; Rosa, Luiz H

    2016-01-01

    This study assessed the diversity of cultivable rock-associated fungi from Atacama Desert. A total of 81 fungal isolates obtained were identified as 29 Ascomycota taxa by sequencing different regions of DNA. Cladosporium halotolerans, Penicillium chrysogenum and Penicillium cf. citrinum were the most frequent species, which occur at least in four different altitudes. The diversity and similarity indices ranged in the fungal communities across the latitudinal gradient. The Fisher-α index displayed the higher values for the fungal communities obtained from the siltstone and fine matrix of pyroclastic rocks with finer grain size, which are more degraded. A total of 23 fungal extracts displayed activity against the different targets screened. The extract of P. chrysogenum afforded the compounds α-linolenic acid and ergosterol endoperoxide, which were active against Cryptococcus neoformans and methicillin-resistance Staphylococcus aureus respectively. Our study represents the first report of a new habitat of fungi associated with rocks of the Atacama Desert and indicated the presence of interesting fungal community, including species related with saprobes, parasite/pathogen and mycotoxigenic taxa. The geological characteristics of the rocks, associated with the presence of rich resident/resilient fungal communities suggests that the rocks may provide a favourable microenvironment fungal colonization, survival and dispersal in extreme conditions. PMID:26235221

  12. Pollen analyses from a 50 000-yr rodent midden series in the southern Atacama Desert (25° 300' S)

    Science.gov (United States)

    Maldonado, Antonio; Betancourt, Julio L.; Latorre, Claudio; Villagran, Carolina

    2005-01-01

    Precipitation in northern Chile is controlled by two great wind belts—the southern westerlies over the southern Atacama and points south (>24° S) and the tropical easterlies over the northern and central Atacama Desert (16–24° S). At the intersection of these summer and winter rainfall regimes, respectively, is a Mars-like landscape consisting of expansive surfaces devoid of vegetation (i.e. absolute desert) except in canyons that originate high enough to experience runoff once every few years. Pollen assemblages from 39 fossil rodent middens in one of these canyons, Quebrada del Chaco (25° 30' S), were used to infer the history of vegetation and precipitation at three elevations (2670–800 m; 3100–3200 m; 3450–3500 m) over the past 50 000 years. When compared to modern conditions and fossil records to the north and south, the pollen evidence indicates more winter precipitation at >52, 40–33, 24–17 k cal.yrBP, more precipitation in both seasons at 17–14 k cal. yr BP, and more summer precipitation from 14–11 k cal. yr BP. Younger middens are scarce at Quebrada del Chaco, and the few Holocene samples indicate hyperarid conditions comparable to today. The only exception is a pollen assemblage that indicates a brief but significant interlude of increased winter precipitation in the last millennium.

  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. Soils at the hyperarid margin: The isotopic composition of soil carbonate from the Atacama Desert, Northern Chile

    Science.gov (United States)

    Quade, Jay; Rech, Jason A.; Latorre, Claudio; Betancourt, Julio L.; Gleeson, Erin; Kalin, Mary T.K.

    2007-01-01

    We evaluate the impact of exceptionally sparse plant cover (0–20%) and rainfall (2–114 mm/yr) on the stable carbon and oxygen composition of soil carbonate along elevation transects in what is among the driest places on the planet, the Atacama Desert in northern Chile. δ13C and δ18O values of carbonates from the Atacama are the highest of any desert in the world. δ13C (VPDB) values from soil carbonate range from -8.2% at the wettest sites to +7.9% at the driest. We measured plant composition and modeled respiration rates required to form these carbonate isotopic values using a modified version of the soil diffusion model of [Cerling (1984) Earth Planet. Sci. Lett.71, 229–240], in which we assumed an exponential form of the soil CO2 production function, and relatively shallow (20–30 cm) average production depths. Overall, we find that respiration rates are the main predictor of the δ13C value of soil carbonate in the Atacama, whereas the fraction C3 to C4 biomass at individual sites has a subordinate influence. The high average δ13C value (+4.1%) of carbonate from the driest study sites indicates it formed&mdahs;perhaps abiotically—in the presence of pure atmospheric CO2. δ18O (VPDB) values from soil carbonate range from -5.9% at the wettest sites to +7.3% at the driest and show much less regular variation with elevation change than δ13C values. δ18O values for soil carbonate predicted from local temperature and δ18O values of rainfall values suggest that extreme (>80% in some cases) soil dewatering by evaporation occurs at most sites prior to carbonate formation. The effects of evaporation compromise the use of δ18O values from ancient soil carbonate to reconstruct paleoelevation in such arid settings.

  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. 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....

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

    OpenAIRE

    Hansen, Anders Cai Holm; Paulino-Lima, Ivan Glaucio; Fujishima, Kosuke; Rothschild, Lynn Justine; Jensen, Peter Ruhdal

    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.

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

    Science.gov (United States)

    Holm Hansen, Anders Cai; Paulino-Lima, Ivan Glaucio; Fujishima, Kosuke; Rothschild, Lynn Justine; Jensen, Peter Ruhdal

    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. PMID:26868392

  1. Rodent middens reveal episodic, long-distance plant colonizations across the hyperarid Atacama Desert over the last 34,000 years

    Science.gov (United States)

    Diaz, Francisca P.; Latorre, Claudio; Maldonado, Antonio; Quade, Jay; Betancourt, Julio L.

    2012-01-01

    Aim To document the impact of late Quaternary pluvial events on plant movements between the coast and the Andes across the Atacama Desert, northern Chile. Location Sites are located along the lower and upper fringes of absolute desert (1100–2800 m a.s.l.), between the western slope of the Andes and the Coastal Ranges of northern Chile (24–26° S). Methods We collected and individually radiocarbon dated 21 rodent middens. Plant macrofossils (fruits, seeds, flowers and leaves) were identified and pollen content analysed. Midden assemblages afford brief snapshots of local plant communities that existed within the rodents' limited foraging range during the several years to decades that it took the midden to accumulate. These assemblages were then compared with modern floras to determine the presence of extralocal species and species provenance. Results Five middens span the last glacial period (34–21 ka) and three middens are from the last glacial–interglacial transition (19–11 ka). The remaining 13 middens span the last 7000 years. Coastal hyperarid sites exhibit low taxonomic richness in middens at 19.3, 1.1, 1.0, 0.9, 0.5 ka and a modern sample. Middens are also dominated by the same plants that occur today. In contrast, middens dated to 28.1, 21.3, 17.3, 3.7 and 0.5 ka contain more species, including Andean extralocals. Precordillera middens (c. 2700 m) show a prominent increase in plant macrofossil richness, along with the appearance of Andean extralocals and sedges at 34.5 and 18.9 ka. Six younger middens dated to 6.1–0.1 ka are similar to the modern local vegetation. Main conclusions Increased species richness and Andean extralocal plants occurred along the current lower fringes of absolute desert during the last glacial–interglacial transition and late Holocene. The absence of soil carbonates indicates the persistence of absolute desert throughout the Quaternary. Colonization by Andean plants could have been accomplished through long-distance seed

  2. 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

  3. Ancient and Modern Salars of the Atacama Desert, Chile: A Terrestrial Analog for Evaporite Formation on Mars

    Science.gov (United States)

    Jungers, M. C.; Amundson, R.; Heimsath, A. M.; Christensen, P. R.; Edwards, C. S.

    2010-12-01

    The hyperarid (Atacama Desert of northern Chile is a widely accepted terrestrial analog for the surface of Mars. Sulfate and chloride deposits are present in uncommonly high abundances throughout the Atacama. The formation and preservation of these evaporite deposits are a direct result of the arid-hyperarid climate of the region from the Triassic to the present. Mars, too, is known for a long history of aridity. Remotely sensed data from THEMIS, TES, and analyses conducted during Mars landing missions have revealed the presence of sulfate and chloride deposits covering some portions of Mars’ surface. We synthesize remotely sensed (ASTER) data from the Atacama with field observations and sample analyses by laboratory thermal spectroscopy and portable XRF to inform how best to interpret signatures of sulfate and chloride deposits on Mars. We focus on two salars, one ancient (Salar de Llamara) and one modern (Salar de Atacama), to better understand how evaporites’ spectral and geochemical signatures may evolve through time. The oldest deposits of the Salar de Llamara are Miocene in age, while the Salar de Atacama continues to develop today. Compositionally, both salars’ surfaces are dominated by sulfate (gypsum and anhydrite) and chloride (halite) deposits. We selected sample sites according to compositional boundaries inferred from decorrelation stretches of thermal infrared (TIR) ASTER bands supplemented by previous field reconnaissance. We collected surface samples along transects from the core of the salars to their shorelines, intersecting zones ranging from predominantly sulfate or chloride to near equal mixtures of each composition. This transect approach to sampling allowed us to collect samples that incorporated a range of both geochemical compositions and processes fundamental to the spatial and temporal evolution of evaporite deposits. Preliminary results show promise in refining our ability to identify sulfates and chlorides using lab spectra, and

  4. 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

  5. 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...

  6. 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

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

    OpenAIRE

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

    2007-01-01

    We analyze remarkable examples of the large (similar to 10,000 km(2)) and local-scale (similar to 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, similar to 1:1000 s...

  8. 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 adaptation

  9. 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

  10. 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

  11. 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...

  12. 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

    OpenAIRE

    Vítek, Petr; Jehlicka, J.; H. G. M. Edwards; Hutchinson, Ian; Ascaso, Carmen; Wierzchos, Jacek

    2012-01-01

    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, pow...

  13. 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 < -3.5??? for other Hamburgo Basin waters; thus the mine waters may represent a mixture of meteoric waters with deeper "metamorphic" waters, which had interacted with rocks and exchanged oxygen 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

  14. Distribution of scytonemin in endolithic microbial communities from halite crusts in the hyperarid zone of the Atacama Desert, Chile.

    Science.gov (United States)

    Vítek, Petr; Jehlička, Jan; Ascaso, Carmen; Mašek, Vlastimil; Gómez-Silva, Benito; Olivares, Héctor; Wierzchos, Jacek

    2014-11-01

    Scytonemin, a UV-screening molecule produced by certain Cyanobacteria to protect against harmful UV radiation, was studied in endolithic cyanobacterial colonies in the halite crust from one of the driest places on Earth - the hyperarid zone of the Atacama Desert. The distribution of the pigment within the evaporitic crust was studied in detail by various independent analytical methods: Raman spectroscopy (including Raman imaging); advanced microscopic observations (fluorescence microscopy, confocal laser scanning microscopy, low-temperature scanning electron microscopy); and spectrophotometric analyses. The differences in scytonemin biosynthesis were mapped within the colonized interior layers, which can be divided into scytonemin-rich and scytonemin-poor zones. A 532 nm laser for excitation proved to be an ideal excitation source with which to observe the relative content of scytonemin within a particular cell aggregate, as well as between different cell aggregates; based on the scytonemin/carotenoid Raman signal intensity ratio of selected corroborative bands for these two compounds. Significantly, scytonemin was found to accumulate within a decayed biomass in the surface portions of the halite crust. These were found to be highly enriched in both the absolute scytonemin content (as documented by UV/VIS spectrophotometry) and its content relative to other pigments associated with the cyanobacterial cells (e.g. carotenoids and chlorophyll). PMID:25056905

  15. 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. PMID:25438126

  16. Metal mobilization by iron- and sulfur-oxidizing bacteria in a multiple extreme mine tailings in the Atacama Desert, Chile.

    Science.gov (United States)

    Korehi, H; Blöthe, M; Sitnikova, M A; Dold, B; Schippers, A

    2013-03-01

    The marine shore sulfidic mine tailings dump at the Chañaral Bay in the Atacama Desert, northern Chile, is characterized by extreme acidity, high salinity, and high heavy metals concentrations. Due to pyrite oxidation, metals (especially copper) are mobilized under acidic conditions and transported toward the tailings surface and precipitate as secondary minerals (Dold, Environ. Sci. Technol. 2006, 40, 752-758.). Depth profiles of total cell counts in this almost organic-carbon free multiple extreme environment showed variable numbers with up to 10(8) cells g(-1) dry weight for 50 samples at four sites. Real-time PCR quantification and bacterial 16S rRNA gene diversity analysis via clone libraries revealed a dominance of Bacteria over Archaea and the frequent occurrence of the acidophilic iron(II)- and sulfur-oxidizing and iron(III)-reducing genera Acidithiobacillus, Alicyclobacillus, and Sulfobacillus. Acidophilic chemolithoautotrophic iron(II)-oxidizing bacteria were also frequently found via most-probable-number (MPN) cultivation. Halotolerant iron(II)-oxidizers in enrichment cultures were active at NaCl concentrations up to 1 M. Maximal microcalorimetrically determined pyrite oxidation rates coincided with maxima of the pyrite content, total cell counts, and MPN of iron(II)-oxidizers. These findings indicate that microbial pyrite oxidation and metal mobilization preferentially occur in distinct tailings layers at high salinity. Microorganisms for biomining with seawater salt concentrations obviously exist in nature. PMID:23373853

  17. 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...

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

    OpenAIRE

    Despland, Emma

    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 5000 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...

  19. Bacterial Composition and Quantitation in the Yungay Region of the Atacama Desert, Chile

    Science.gov (United States)

    Fletcher, Lauren; Conley, Catharine A.; Ishkhanova, Galina; Kovacs, Gregory; Jordan, Jeanne; Cullings, Ken; Gomez-Silva, Benito; McKay, Christopher

    2006-01-01

    Voyager would have produced similar negative results if tested in the Yungay region (Navarro-Gonzales et al, 2003). However, the number of bacteria present per gr'am in the Yungay sands is not well-established, being below the detection limit of culture methods. For the past several years, this group has been analyzing Yungay sands by quantitative Polymerase Chain Reaction (qPCR), both in the lab and in the field, to establish protocols for counting bacteria. We use primers that detect a broad range of bacterial taxa, including both proteobacteria and firmicutes. Optimization of DNA extraction and qPCR analysis is critical for accurate counts. Comparison of qPCR results with PhosphoLipid Fatty Acid (PLFA)-analysis and other counting methods indicates that there are detectable bacteria in sand obtained from the upper few centimeters of the desert surface.

  20. 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.

  1. Microbial characterization of microbial ecosystems associated to evaporites domes of gypsum in Salar de Llamara in Atacama desert.

    Science.gov (United States)

    Rasuk, Maria Cecilia; Kurth, Daniel; Flores, Maria Regina; Contreras, Manuel; Novoa, Fernando; Poire, Daniel; Farias, Maria Eugenia

    2014-10-01

    The Central Andes in northern Chile contains a large number of closed basins whose central depression is occupied by saline lakes and salt crusts (salars). One of these basins is Salar de Llamara (850 m a.s.l.), where large domed structures of seemingly evaporitic origin forming domes can be found. In this work, we performed a detailed microbial characterization of these domes. Mineralogical studies revealed gypsum (CaSO(4)) as a major component. Microbial communities associated to these structures were analysed by 454 16S rDNA amplicon sequencing and compared between winter and summer seasons. Bacteroidetes Proteobacteria and Planctomycetes remained as the main phylogenetic groups, an increased diversity was found in winter. Comparison of the upper air-exposed part and the lower water-submerged part of the domes in both seasons showed little variation in the upper zone, showing a predominance of Chromatiales (Gammaproteobacteria), Rhodospirillales (Alphaproteobacteria), and Sphingobacteriales (Bacteroidetes). However, the submerged part showed marked differences between seasons, being dominated by Proteobacteria (Alpha and Gamma) and Verrucomicrobia in summer, but with more diverse phyla found in winter. Even though not abundant by sequence, Cyanobacteria were visually identified by scanning electron microscopy (SEM), which also revealed the presence of diatoms. Photosynthetic pigments were detected by high-performance liquid chromatography, being more diverse on the upper photosynthetic layer. Finally, the system was compared with other endoevaporite, mats microbialite and Stromatolites microbial ecosystems, showing higher similitude with evaporitic ecosystems from Atacama and Guerrero Negro. This environment is of special interest for extremophile studies because microbial life develops associated to minerals in the driest desert all over the world. Nevertheless, it is endangered by mining activity associated to copper and lithium extraction; thus, its

  2. 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

  3. 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.

  4. 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.

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

    Science.gov (United States)

    Despland, Emma

    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 5000 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. PMID:25309583

  6. 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

  7. 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

  8. 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.

  9. 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. PMID:26147800

  10. 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

  11. 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. PMID:27000320

  12. 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

  13. Microbial diversity and the presence of algae in halite endolithic communities are correlated to atmospheric moisture in the hyper-arid zone of the Atacama Desert.

    Science.gov (United States)

    Robinson, Courtney K; Wierzchos, Jacek; Black, Celeste; Crits-Christoph, Alexander; Ma, Bing; Ravel, Jacques; Ascaso, Carmen; Artieda, Octavio; Valea, Sergio; Roldán, Mònica; Gómez-Silva, Benito; DiRuggiero, Jocelyne

    2015-02-01

    The Atacama Desert is one of the oldest and driest deserts in the world, and its hyper-arid core is described as 'the most barren region imaginable'. We used a combination of high-throughput sequencing and microscopy methods to characterize the endolithic microbial assemblages of halite pinnacles (salt rocks) collected in several hyper-arid areas of the desert. We found communities dominated by archaea that relied on a single phylotype of Halothece cyanobacteria for primary production. A few other phylotypes of salt-adapted bacteria and archaea, including Salinibacter, Halorhabdus, and Halococcus were major components of the halite communities, indicating specific adaptations to the unique halite environments. Multivariate statistical analyses of diversity metrics clearly separated the halite communities from that of the surrounding soil in the Yungay area. These analyses also revealed distribution patterns of halite communities correlated with atmospheric moisture. Microbial endolithic communities from halites exposed to coastal fogs and high relative humidity were more diverse; their archaeal and bacterial assemblages were accompanied by a novel algae related to oceanic picoplankton of the Mamiellales. In contrast, we did not find any algae in the Yungay pinnacles, suggesting that the environmental conditions in this habitat might be too extreme for eukaryotic photosynthetic life. PMID:24372972

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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

  20. Molecular preservation in halite- and perchlorate-rich hypersaline subsurface deposits in the Salar Grande basin (Atacama Desert, Chile): Implications for the search for molecular biomarkers on Mars

    Science.gov (United States)

    FernáNdez-Remolar, D. C.; Chong-DíAz, G.; RuíZ-Bermejo, M.; Harir, M.; Schmitt-Kopplin, P.; Tziotis, D.; Gómez-OrtíZ, D.; GarcíA-Villadangos, M.; MartíN-Redondo, M. P.; Gómez, F.; RodríGuez-Manfredi, J. A.; Moreno-Paz, M.; de Diego-Castilla, G.; EcheverríA, A.; Urtuvia, V. N.; Blanco, Y.; Rivas, L.; Izawa, M. R. M.; Banerjee, N. R.; Demergasso, C.; Parro, V.

    2013-06-01

    Similarities between the Atacama Desert (Chile) and Mars include extreme aridity, highly oxidizing chemistry, and intense ultraviolet radiation that promoted the photochemical production of perchlorates and nitrates. Concentration of these ions under hyperarid conditions led to the formation of nitrate- and perchlorate-bearing deposits in ephemeral lakes, followed by later deposition of chlorides and sulfates. At some locations, such as the Salar Grande, hypersaline deposits have remained unaltered for millions of years. We conducted a drilling campaign in deposits of the Salar to characterize the preservation state of biological molecules. A 5 m deep discontinuous core was recovered and subjected to multitechnique analysis including the antibody microarray-based biosensor LDChip300 and the SOLID (Signs Of Life Detector) instrument, complemented by geophysical, mineralogical, geochemical, and molecular analysis. We identified two units based on the mineralogy: the upper one, from the surface to ~320 cm depth characterized by a predominance of halite and anhydrite, and the lower one, from 320 to 520 cm, with a drop in halite and anhydrite and an enrichment in nitrate and perchlorate. Organic compounds including biomolecules were detected in association with the different depositional and mineralogical units, demonstrating the high capacity for molecular preservation. Hypersaline environments preserve biomolecules over geologically significant timescales; therefore, salt-bearing materials should be high-priority targets for the search for evidence of life on Mars.

  1. Macaria mirthae Vargas et al (Lepidoptera: Geometridae): Confirmation of the Use of an Invasive Host Plant in the Northern Atacama Desert of Chile Based on DNA Barcodes.

    Science.gov (United States)

    Rivera-Cabello, D; Huanca-Mamani, W; Vargas, H A

    2015-08-01

    Macaria mirthae Vargas et al (Lepidoptera: Geometridae) is a geometrid moth native to the northern Atacama Desert of Chile. Its oligophagous larvae are associated with native hosts of the plant family Fabaceae, the most important of which is Acacia macracantha. The invasive tree Leucaena leucocephala (Fabaceae) was recently recorded as a host plant for M. mirthae based on morphology. The taxonomic status of larvae collected on A. macracantha and L. leucocephala was assessed using sequences of the DNA barcode fragment of the cytochrome c oxidase subunit I (COI) gene. Genetic divergence between samples from the host plants was found to be 0%-0.8% (Kimura 2-parameter model). Neighbor-joining and maximum likelihood analyses were also performed, including additional barcode sequences of Neotropical geometrid moths from GenBank and BOLD databases. Sequences of the larvae from both host plants clustered in a single clade with high statistical support in both analyses. Based on these results, it is concluded that M. mirthae has effectively expanded its host range and its larvae are currently feeding on the exotic tree L. leucocephala. Additionally, the importance of this new host association in a highly disturbed habitat is briefly discussed in terms of the field biology of this native geometrid moth. PMID:26174961

  2. Antifungal activity of extracts from Atacama Desert fungi againstParacoccidioides brasiliensis and identification ofAspergillus felis as a promising source of natural bioactive compounds

    Directory of Open Access Journals (Sweden)

    Graziele Mendes

    2016-03-01

    Full Text Available 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.

  3. 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

  4. 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.

  5. APECS - The Atacama Pathfinder Experiment Control System

    OpenAIRE

    Muders, D.; Hafok, H.; Wyrowski, F.; Polehampton, E.; Belloche, A.; Koenig, C.; Schaaf, R.; Schuller, F.; Hatchell, J.; Tak, F. v. d.

    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 co...

  6. 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...

  7. Stable isotopic composition of soil calcite (O, C) and gypsum (S) overlying Cu deposits in the Atacama Desert, Chile: Implications for mineral exploration, salt sources, and paleoenvironmental reconstruction

    International Nuclear Information System (INIS)

    Highlights: ► We collected soils overlying two porphyry copper deposits and a pampa, Atacama Desert, Chile. ► δ18O for calcite over fracture zones at the Spence deposit suggests involvement of earthquake-induced groundwater. ► S isotopes in gypsum at Spence also indicates involvement of groundwater, consistent with elevated Cu, Se, I. ► At Gaby Sur and Tamarugal, S isotopes cannot distinguish sulfur of porphyry from redeposited sulfate from interior salars. ► The three sites studied have had different histories of salt accumulation and display variable influence of groundwater. - Abstract: Soils overlying two porphyry Cu deposits (Spence, Gaby Sur) and the Pampa del Tamarugal, Atacama Desert, Northern Chile were collected in order to investigate the extent to which saline groundwaters influence “soil” chemistry in regions with thick Miocene and younger sediment cover. Soil carbonate (calcite) was analyzed for C and O isotopes and pedogenic gypsum for S isotopes. Soil calcite is present in all soils at the Spence deposit, but increases volumetrically above two fracture zones that cut the Miocene gravels, including gravels that overlie the deposit. The C isotope composition of carbonate from the soils overlying fracture zones is indistinguishable from pedogenic carbonate elsewhere at the Spence deposit; all δ13CVPDB values fall within a narrow range (1.40–4.23‰), consistent with the carbonate having formed in equilibrium with atmospheric CO2. However, δ18OVPDB for carbonate over both fracture zones is statistically different from carbonate elsewhere (average δ18OVPDB = 0.82‰ vs. −2.23‰, respectively), suggesting involvement of groundwater in their formation. The composition of soils at the Tamarugal anomaly has been most strongly affected by earthquake-related surface flooding and evaporation of groundwater; δ13CVPDB values (−4.28‰ to −2.04‰) are interpreted to be a mixture of dissolved inorganic C (DIC) from groundwater and

  8. Phylogeny of Nolana (Solanaceae) of the Atacama and Peruvian deserts inferred from sequences of four plastid markers and the nuclear LEAFY second intron.

    Science.gov (United States)

    Tu, Tieyao; Dillon, Michael O; Sun, Hang; Wen, Jun

    2008-11-01

    The phylogeny of Nolana (Solanaceae), a genus primarily distributed in the coastal Atacama and Peruvian deserts with a few species in the Andes and one species endemic to the Galápagos Islands, was reconstructed using sequences of four plastid regions (ndhF, psbA-trnH, rps16-trnK and trnC-psbM) and the nuclear LEAFY second intron. The monophyly of Nolana was strongly supported by all molecular data. The LEAFY data suggested that the Chilean species, including Nolana sessiliflora, the N. acuminata group and at least some members of the Alona group, are basally diverged, supporting the Chilean origin of the genus. Three well-supported clades in the LEAFY tree were corroborated by the SINE (short interspersed elements) or SINE-like insertions. Taxa from Peru are grouped roughly into two clades. Nolana galapagensis from the Galápagos Island is most likely to have derived from a Peruvian ancestor. The monophyly of the morphologically well-diagnosed Nolana acuminata group (N. acuminata, N. baccata, N. paradoxa, N. parviflora, N. pterocarpa, N. rupicola and N. elegans) was supported by both plastid and LEAFY data. Incongruence between the plastid and the LEAFY data was detected concerning primarily the positions of N. sessiliflora, N. galapagensis, taxa of the Alona group and the two Peruvian clades. Such incongruence may be due to reticulate evolution or in some cases lineage sorting of plastid DNA. Incongruence between our previous GBSSI trees and the plastid-LEAFY trees was also detected concerning two well-supported major clades in the GBSSI tree. Duplication of the GBSSI gene may have contributed to this incongruence. PMID:18722540

  9. A new cecidogenous species of Eugnosta Hübner (Lepidoptera: Tortricidae) associated with Baccharis salicifolia (Asteraceae) in the northern Chilean Atacama Desert: Life-history description and phylogenetic inferences.

    Science.gov (United States)

    Vargas, Héctor A; Pollo, Pietro; Basilio, Daniel S; Gonçalves, Gislene L; Moreira, Gilson R P

    2015-01-01

    Eugnosta Hübner, 1825 (Lepidoptera, Tortricidae, Tortricinae, Cochylini, Cochylina) is reported for the first time in Chile. Male and female adults, the pupa, the last-instar larva, and galls of Eugnosta azapaensis Vargas & Moreira, sp. n., are described and illustrated from the Azapa Valley in the northern Atacama Desert. The larvae induce fusiform galls on shoots of the shrub Baccharis salicifolia (Ruiz & Pav.) Pers. (Asteraceae). An assessment of phylogenetic relationships of E. azapaensis with two congeneric species based on mitochondrial DNA is provided. PMID:25781249

  10. 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

  11. 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.

  12. ALMA (Atacama Large Millimetre/ Submillimetre Array)

    OpenAIRE

    Barcons, Xavier

    2010-01-01

    ALMA is a large sub/millimetre observatory in construction phase (Atacama desert, Chile). When finished it will be the world’s largest interferometer for millimetre and submillimetre wavelengths. Three sites: 1)Array Operations Site (AOS), llano de Chajnantor (5100 m). 2)Operations Support Facility (OSF), near San Pedro de Atacama (2900m). 3)Santiago Central Office (SCO). First large ground-based “global” scientific infrastructure.

  13. A small, new gerbil-mouse Eligmodontia (Rodentia: Cricetidae) from dunes at the coasts and deserts of north-central Chile: molecular, chromosomic, and morphological analyses.

    Science.gov (United States)

    Spotorno, Angel E; Zuleta, Carlos; Walker, Laura I; Manriquez, German; Valladares, Pablo; Marin, Juan C

    2013-01-01

    A small, new species of gerbil rodents of the genus Eligmodontia from the southwestern dunes of the Atacama Desert in northern Chile is described; the genus had not been reported for this western lowland region. Our description is based on cytogenetic and molecular data, as well as cranial and external morphology. In order to support this hypothesis, we studied 27 specimens captured in Playa Los Choros (Coquimbo) and Copiapó (Atacama), comparing them with samples of all the extant species of the genus. Nineteen individuals consistently showed 2N=50, FN=48, with telocentric chromosomes and G-bands identical to those of the geographically northeastern E. hirtipes; these two groups were geographically separated by E. puerulus (2N = 34, FN = 48). The phylogenetic analysis of 56 Eligmodontia cytochrome-b gene sequences yielded a maximum-likelihood phylogenetic tree where the new species formed a divergent and well-supported clade within the genus, which was also confirmed by unweighted parsimony, minimum evolution, and Bayesian analyses. The new species has K2P genetic distances of 12.8% from the geographically distant E. hirtipes, and 10.3% from E. puerulus. Axes 1 and 2 of Principal Component Analysis based on 12 body and skull measurements clearly separated the new species, the latter having a smaller head+body length (70.6 +/- 3.4 mm, n = 17) and lower weight (11.9 +/- 1.9 g, n = 20). We provide strong evidence to recognize a distinct new western lineage within Eligmodontia genus, Eligmodontia dunaris sp. nov., for which we give a complete taxonomic description and a hypothetical biogeographic scenario. The new species should be considered endangered, due to its level of endemism, its low population numbers (which can be occasionally increased after a blooming desert) and its fragile dry habitat patchily distributed near the Atacama Desert. PMID:25250459

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

    Directory of Open Access Journals (Sweden)

    JOSÉ ANTONIO GONZÁLEZ

    2011-05-01

    Full Text Available 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, students and relations between primary school teachers and nitrate companies. Key words: Schools, Nitrate mines, Atacama Desert, Antofagasta.

  15. 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...

  16. Dynamics within geyser conduits, and sensitivity to environmental perturbations: Insights from a periodic geyser in the El Tatio geyser field, Atacama Desert, Chile

    Science.gov (United States)

    Munoz-Saez, Carolina; Manga, Michael; Hurwitz, Shaul; Rudolph, Maxwell L.; Namiki, Atsuko; Wang, Chi-Yuen

    2015-02-01

    Despite more than 200 years of scientific study, the internal dynamics of geyser systems remain poorly characterized. As a consequence, there remain fundamental questions about what processes initiate and terminate eruptions, and where eruptions begin. Over a one-week period in October 2012, we collected down-hole measurements of pressure and temperature in the conduit of an exceptionally regular geyser (132 s/cycle) located in the Chilean desert. We identified four stages in the geyser cycle: (1) recharge of water into the conduit after an eruption, driven by the pressure difference between water in the conduit and in a deeper reservoir; (2) a pre-eruptive stage that follows the recharge and is dominated by addition of steam from below; (3) the eruption, which occurs by rapid boiling of a large mass of water at the top of the water column, and decompression that propagates boiling conditions downward; and (4) a relaxation stage during which pressure and temperature decrease until conditions preceding the recharge stage are restored. Eruptions are triggered by the episodic addition of steam coming from depth, suggesting that the dynamics of the eruptions are dominated by geometrical and thermodynamic complexities in the conduit and reservoir. Further evidence favoring the dominance of internal processes in controlling periodicity is also provided by the absence of responses of the geyser to environmental perturbations (air pressure, temperature and probably also Earth tides).

  17. Dynamics within geyser conduits, and sensitivity to environmental perturbations: insights from a periodic geyser in the El Tatio Geyser Field, Atacama Desert, Chile

    Science.gov (United States)

    Munoz-Saez, Carolina; Manga, Michael; Hurwitz, Shaul; Rudolph, Maxwell L.; Namiki, Atsuko; Wang, Chi-Yuen

    2015-01-01

    Despite more than 200 years of scientific study, the internal dynamics of geyser systems remain poorly characterized. As a consequence, there remain fundamental questions about what processes initiate and terminate eruptions, and where eruptions begin. Over a one-week period in October 2012, we collected down-hole measurements of pressure and temperature in the conduit of an exceptionally regular geyser (132 s/cycle) located in the Chilean desert. We identified four stages in the geyser cycle: (1) recharge of water into the conduit after an eruption, driven by the pressure difference between water in the conduit and in a deeper reservoir; (2) a pre-eruptive stage that follows the recharge and is dominated by addition of steam from below; (3) the eruption, which occurs by rapid boiling of a large mass of water at the top of the water column, and decompression that propagates boiling conditions downward; (4) a relaxation stage during which pressure and temperature decrease until conditions preceding the recharge stage are restored. Eruptions are triggered by the episodic addition of steam coming from depth, suggesting that the dynamics of the eruptions are dominated by geometrical and thermodynamic complexities in the conduit and reservoir. Further evidence favoring the dominance of internal processes in controlling periodicity is also provided by the absence of responses of the geyser to environmental perturbations (air pressure, temperature and probably also Earth tides).

  18. 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)

  19. 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.

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

    OpenAIRE

    Juan Francisco Araya; Ricardo Catalán

    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 recor...

  1. The Atacama Large Millimeter/submillimeter Array: Overview & status

    OpenAIRE

    Beasley, A. J.; Murowinski, R.; Tarenghi, M.

    2006-01-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) is an international radio telescope under construction in the Atacama Desert of northern Chile. ALMA will be situated on a high-altitude site at 5000 m elevation which provides excellent atmospheric transmission over the instrument wavelength range of 0.3 to 3 mm. ALMA will be comprised of two key observing components: an array of up to sixty-four 12-m diameter antennas arranged in a multiple configurations ranging in size from 0.15 to ~...

  2. Atacama Compact Array Antennas

    OpenAIRE

    Saito, Masao; Inatani, Junji; Nakanishi, Kouichiro; Naoi, Takahiro; Yamada, Masumi; Saito, Hiro; Ikenoue, Bungo; Kato, Yoshihiro; Morita, Kou-ichiro; Mizuno, Norikazu; Iguchi, Satoru

    2011-01-01

    We report major performance test results of the Atacama Compact Array (ACA) 7-m and 12-m antennas of ALMA (Atacama Large Millimeter/submillimeter Array). The four major performances of the ACA antennas are all-sky pointing (to be not more than 2.0 arcsec), offset pointing (to be < 0.6 arcsec) surface accuracy (< 25(20) micrometer for 12(7)m-antenna), stability of path-length (15 micrometer over 3 min), and high servo capability (6 degrees/s for Azimuth and 3 degrees/s for Elevation). The high...

  3. The Optical/Infrared Astronomical Quality of High Atacama Sites. I. Preliminary Results of Optical Seeing

    OpenAIRE

    Giovanelli, Riccardo; Darling, Jeremy; Sarazin, Marc; Yu, Jennifer; Harvey, Paul; Henderson, Charles; Hoffman, William; Keller, Luke; Barry, Don; Cordes, James; Eikenberry, Stephen; Gull, George; Harrington, Joseph; Smith, J D; Stacey, Gordon

    2001-01-01

    The region surrounding the Llano de Chajnantor, a high altitude plateau in the Atacama Desert in northern Chile, has caught the attention of the astronomical community for its potential as an observatory site. Combining high elevation and extremely low atmospheric water content, the Llano has been chosen as the future site of the Atacama Large Millimeter Array. We have initiated a campaign to investigate the astronomical potential of the region in the optical/infrared. Here, we report on an a...

  4. 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)

    OpenAIRE

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

    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 ...

  5. Atacama Compact Array Antennas

    CERN Document Server

    Saito, Masao; Nakanishi, Kouichiro; Naoi, Takahiro; Yamada, Masumi; Saito, Hiro; Ikenoue, Bungo; Kato, Yoshihiro; Morita, Kou-ichiro; Mizuno, Norikazu; Iguchi, Satoru

    2011-01-01

    We report major performance test results of the Atacama Compact Array (ACA) 7-m and 12-m antennas of ALMA (Atacama Large Millimeter/submillimeter Array). The four major performances of the ACA antennas are all-sky pointing (to be not more than 2.0 arcsec), offset pointing (to be < 0.6 arcsec) surface accuracy (< 25(20) micrometer for 12(7)m-antenna), stability of path-length (15 micrometer over 3 min), and high servo capability (6 degrees/s for Azimuth and 3 degrees/s for Elevation). The high performance of the ACA antenna has been extensively evaluated at the Site Erection Facility area at an altitude of about 2900 meters. Test results of pointing performance, surface performance, and fast motion capability are demonstrated.

  6. The Atacama Cosmology Telescope

    OpenAIRE

    Kosowsky, Arthur

    2004-01-01

    The Atacama Cosmology Telescope (ACT) project is described. This multi-institution collaboration aims to produce arcminute-resolution and micro-Kelvin sensitivity maps of the microwave background temperature over 200 square degrees of the sky in three frequency bands. We give a brief overview of the scientific motivations for such a map, followed by a design outline of our six-meter custom telescope, an overview of our proposed bolometer array detector technology, and site considerations and ...

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

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

    Science.gov (United States)

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

    2016-03-01

    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 yr of reanalysis data from the Climate Forecast System Reanalysis to examine the astroclimatology of Ngari, using the recently-erected Ali Observatory at Shiquanhe (5047 m above mean sea level) as the representative site. We find the percentage of photometric night, median atmospheric seeing and median precipitable water vapour of the Shiquanhe site to be 57 per cent, 0.8 arcsec 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 6000 m heights in the Shiquanhe region. Such possibility should be thoroughly investigated in future.

  13. 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.

  14. Solving the Mystery of the Atacama Nitrate Deposits: The Use of Stable Oxygen Isotope Analysis and Geochemistry

    OpenAIRE

    Ji-Hye Seo

    2011-01-01

    The Atacama Desert, Chile, one of the oldest and driest deserts on Earth, is unique because it contains the largest known nitrate deposits in the world. The origin of these nitrate deposits has been a mystery since their discovery in the 1800s. There are two possible sources of natural nitrate: microbiological processes and photochemical reactions. The majority of material on Earth follows mass-dependent fractionation between stable oxygen isotopes with the abundance of 17Ο (denoted by δ) as ...

  15. Simultaneous seeing measurements at Atacama

    Science.gov (United States)

    Uraguchi, Fumihiro; Motohara, Kentaro; Doi, Mamoru; Takato, Naruhisa; Miyashita, Akihiko; Tanabe, Toshihiko; Oyabu, Shinki; Soyano, Takao

    2004-10-01

    Institute of Astronomy, University of Tokyo is now planning to build a 6.5-m optical-infrared telescope in Atacama, Chile. This project is called "Univ. Tokyo Atacama Observatory (TAO)", and the site evaluation is now under way. As a part of this evaluation process, we started an investigation to compare the astronomical seeing at Atacama with that at Mauna Kea. Here, we report preliminary results of seeing measurements at several sites in Atacama, carried out on October 2003. In order to separate the temporal and site-to-site variation of the seeing, we used two sets of Differential Image Motion Monitors (DIMMs), each of which has two pairs of 7.4 cm sub-apertures with 20.5 cm separation. Three sites were investigated; the point near the TAO weather station (4,950m), the summit of Cello Chico (5,150m) and the point at 5,430m altitude on Cello Toco. Simultaneous measurements were carried out for three half nights out of four half nights measurements. Although the amount of our data is very limited, the results suggest following: 1) Seeing becomes better and more stable as time passing to midnight (eg. From 0."7 to 0."4 at V-band). 2) Higher altitude sites show better seeing than lower altitude sites.

  16. Development of Ground and Remotely Based Evaporation Measurements at the Salar de Atacama, Northern Chile

    Science.gov (United States)

    Kampf, S. K.; Tyler, S. W.; Menz, S. F.; Muñoz, J. F.; Astete, C. O.

    2001-12-01

    Evaporation represents an important component of the water budget in desert playa lakes, and accurate spatial and temporal assessment of evaporation rates has the potential to greatly improve the accuracy of hydrologic models in such environments. To this end, evaporation at the Salar de Atacama, a large playa in the Atacama Desert of northern Chile, has been examined at a variety of spatial and temporal scales. Previous investigators have measured evaporation from the Salar using lysimeters and Bowen Ratio stations and have found that actual evaporation rates in much of the playa are extremely low (Salar are presented along with an assessment of the ability of ASTER imagery to provide accurate measurements of evaporation rates in playa environments.

  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. 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."

  20. OVERVIEW OF THE ATACAMA COSMOLOGY TELESCOPE: RECEIVER, INSTRUMENTATION, AND TELESCOPE SYSTEMS

    International Nuclear Information System (INIS)

    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 m. A 6 m 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 millimeter-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.

  1. Atacama perchlorate as an agricultural contaminant in groundwater: Isotopic and chronologic evidence from Long Island, New York

    Science.gov (United States)

    Böhlke, J.K.; Hatzinger, P.B.; Sturchio, N.C.; Gu, B.; Abbene, I.; Mroczkowski, S.J.

    2009-01-01

    Perchlorate (ClO4-) is a common groundwater constituent with both synthetic and natural sources. A potentially important source of ClO4- is past agricultural application of ClO4--bearing natural NO3- fertilizer imported from the Atacama Desert, Chile, but evidence for this hasbeenlargely circumstantial. Here we report ClO4- stable isotope data (??37Cl, ??18O, and ??17O), along with other supporting chemical and isotopic environmental tracer data, to document groundwater ClO4- contamination sources and history in parts of Long Island, New York. Sampled groundwaters were oxic and ClO4- apparently was not affected by biodegradation within the aquifers. Synthetic ClO4- was indicated by the isotopic method in groundwater near a fireworks disposal site at a former missile base. Atacama ClO4- was indicated in agricultural and urbanizing areas in groundwaters with apparent ages >20 years. In an agricultural area, ClO4- concentrations and ClO4-/NO3- ratios increased withgroundwaterage, possiblybecauseof decreasing application rates of Atacama NO3- fertilizers and/or decreasing ClO4- concentrations in Atacama NO 3- fertilizers in recent years. Because ClO 4-/NO3- ratios of Atacama NO 3- fertilizers imported in the past (???2 ?? 10-3 mol mol-1) were much higher than the ClO 4-/NO3- ratio of recommended drinking-water limits (7 ?? 10-5 mol mol-1 in New York), ClO4- could exceed drinkingwater limits even where NO3- does not, and where Atacama NO3- was only a minor source of N. Groundwater ClO4- with distinctive isotopic composition was a sensitive indicator of past Atacama NO3- fertilizer use on Long Island and may be common in other areas that received NO3- fertilizers from the late 19th century through the 20th century. ?? 2009 American Chemical Society.

  2. Eventos El Niño y episodios lluviosos en el desierto de Atacama: el registro de los últimos dos siglos

    Directory of Open Access Journals (Sweden)

    1995-01-01

    Niño influya directamente sobre la magnitud de las precipitaciones. EL NIÑO EVENTS AND RAINFALL EPISODES IN THE ATACAMA DESERT: THE RECORD OF THE LAST TWO CENTURIES. Along the Pacific coast of South America, El Niño events are characterized by rainfall excesses in northern Peru and in central Chile, while the Altiplano of southern Peru and Bolivia experiment dramatic droughts. In northern Chile rainfall are particularly scarce, and up to now the rainy episodes were not viewed as closely related to El Niño events. In this paper are compiled available data (instrumental record and anecdotic information on rainfall from the Atacama Desert and, more generally from the area extending from Arequipa to Coquimbo, during the last two centuries. The analysis of the gathered data shows that most of the rainy episodes registered in the Norte Grande (Atacama Desert are coeval with El Niño events, although no direct relationship was found between the intensity of the individual El Niño events and the amount of precipitation.

  3. 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

  4. 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.

  5. Long-term denudation rates from the Central Andes (Chile estimated from a Digital Elevation Model using the Black Top Hat function and Inverse Distance Weighting: implications for the Neogene climate of the Atacama Desert Tasas de denudación de largo tiempo en los Andes Centrales, Chile, estimadas a partir de un modelo digital de elevación usando la función 'Top Hat' por cierre y la interpolación ponderada por el inverso de la distancia: implicancias del clima Neógeno del Desierto de Atacama

    Directory of Open Access Journals (Sweden)

    Rodrigo Riquelme

    2008-01-01

    Full Text Available A methodology for determining long-term denudation rates from morphologic markers in a Digital Elevation Model (DEM is checked by a comparative study of two drainage basins in the PrecordiUera of the Central Andes. In both cases the initial configuration of an incised pediment surface has been restored by using two different methods: the Black Top Hat (BTH function and the Inverse Distance Weighting (IDW interpolation. Where vertical incision and hillslope erosion are recorded, the IDW appears to be the most adequate to reconstitute the pediment surfaces. Conversely, where only vertical incision is observed, the BTH describes more precisely the former pediment surfaces and it is easier to solve. By subtracting the DEM from the reconstructed marker we calculated an eroded volume, and estimated its uncertainty by considering Root Mean Square Error (RMSE and DEM grid error. For the last ~10 Myr we obtained long-term denudation rates of 7.33±1.6 m/Myr in the San Andrés drainage basin and 13.59±1.9 m/Myr in the El Salado drainage basin. These estimations are largely in agreement with other reported estimates of long-term denudation rates in the Atacama Desert. Comparison with long-term denudation rates reported in a wide range of climatic regimes suggests that our estimates cannot be explained by the current rainfall in the PrecordiUera. However they could be explained by a rainfall similar to that reported 40 km to the east in the Puna. This suggests that during the time span concerned the geomorphologic evolution of the study area, this evolution is dominated by an orographically controlled rainfall pattern. The preserved pediment surface and the small long term denudation rates determined in this study also indicate that the PrecordiUera was never reached by humid tropical air masses and precipitation as currently observed in the Altiplano during the summer monthsUna metodología para determinar tasas de denudación de largo tiempo a partir de

  6. 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...

  7. 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.

  8. Sources, sinks and long-term cycling of iodine in the hyperarid Atacama continental margin

    Science.gov (United States)

    Álvarez, Fernanda; Reich, Martin; Pérez-Fodich, Alida; Snyder, Glen; Muramatsu, Yasuyuki; Vargas, Gabriel; Fehn, Udo

    2015-07-01

    The Atacama region in northern Chile hosts the driest desert on Earth and is the world's premier iodine production province. The origin of iodine enrichment in Atacama is controversial and fundamentally different processes have been invoked over the years that involve marine, eolian and more recently deep sedimentary fluid and groundwater sources. As a result of the very limited geochemical iodine data in Atacama and the western South American margin, the origin of iodine enrichment in this region still remains elusive. In this study, we present a comprehensive survey of iodine concentrations and isotopic ratios (129I/I) of different reservoirs in the Atacama Desert of northern Chile, including nitrate soils, supergene copper deposits, marine sedimentary rocks, geothermal fluids, groundwater and meteoric water. Nitrate soils along the eastern slope of the Coastal Cordillera are found to have mean iodine concentrations of at least three orders of magnitude higher than the mean crustal abundances of ∼0.12 ppm, with a mean concentration of ∼700 ppm. Soils above giant copper deposits in the Central Depression are also highly enriched in iodine (100's of ppm range), and Cu-iodide and iodate minerals occur in the supergene enrichment zones of some of these deposits. Further east in the Precordillera, Jurassic sedimentary shales and limestones show above-background iodine concentrations, the latter averaging ∼50 ppm in the southern portion of the study area. The highest iodine concentrations in fluids were measured in groundwater below nitrate soils in the Coastal Range (∼3.5-10 ppm) and in geothermal waters (1-3 ppm) along the volcanic arc. Although highly variable, the iodine isotopic ratios (129I/I) of Jurassic marine sedimentary rocks (∼300-600 × 10-15), nitrate soils (∼150-1500 × 10-15) and waters (∼215 × 10-15) are consistently low (factors has played an unforeseen role in transporting and accumulating iodine and other soluble components in the

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

    Directory of Open Access Journals (Sweden)

    Juan Francisco Araya

    2014-04-01

    Full Text Available 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.

  10. Atacama Compact Array Correlator for Atacama Large Millimeter/submillimeter Array

    OpenAIRE

    Okumura, Sachiko K.; Chikada, Yoshihiro; Kamazaki, Takeshi; Okuda, Takeshi; Kurono, Yasutaka; Iguchi, Satoru

    2011-01-01

    We have developed a FX-architecture digital spectro-correlator, Atacama Compact Array Correlator for the Atacama Large Millimeter/submillimeter Array. The ACA Correlator processes four pairs of dual polarization signals, whose bandwidth is 2 GHz, from up to sixteen antennas, and calculates auto- and cross-correlation spectra including cross-polarization in all combinations of sixteen antennas. We report the detailed design of the correlator and the verification results of the correlator hardw...

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

    OpenAIRE

    Chávez Oyanadel, R.O.; Clevers, J G P W; Verbesselt, J.; Naulin, P.; M. Herold

    2014-01-01

    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...

  12. Detecting Leaf Pulvinar Movements on NDVI Time Series of Desert Trees: A New Approach for Water Stress Detection

    OpenAIRE

    2014-01-01

    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...

  13. 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

  14. 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

  15. 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

  16. Licancabur Volcano, Bolivia and life in the Atacama: Environmental physics and analogies to Mars

    Science.gov (United States)

    Hock, Andrew Nelson

    Although there is no perfect environmental analog to Mars on Earth, quantitative study of relevant terrestrial field sites can serve as the basis for physical models and technology development to aid future exploration. This dissertation describes original field and laboratory research on two terrestrial analog sites: Licancabur Volcano, Bolivia, and the Atacama Desert, Chile. Atop Licancabur, at an elevation of nearly 6,000 meters above sea level, sits the highest volcanic lake on Earth. Prior to this work, little was known about the lake, its waters, the role of volcanism or its potential relationship to locales on Mars. In the first part of this work, I describe observations of the lake resulting from several years of field study, including data on meteorological conditions and solar irradiance. These and other measurements provide the basis for (1) the first quantitative mass and energy balance model of the lake, and (2) the first determination of the altitude effect on solar visible and ultraviolet flux from the high altitude summit. Under the observed conditions, model results indicate: lake waters are primarily meteoric in origin and evaporating rapidly; volcanic input is not required to explain observations of lake water temperature or year-end model results. Nearby, Chile's Atacama Desert is known to be one of the driest, most inhospitable environments on Earth. There, environmental similarities to Mars provide an apt testing ground for new astrobiological exploration technologies. In the latter part of this work, I present results from my work with the Life In The Atacama (LITA) Mars rover field experiment. In particular, I report on the development of a new data analysis tool named the LITA Data Scoring System (DSS). Subject to the user-defined constraints, the DSS was used to facilitate targeting, analysis and mapping of rover science results relevant to potential habitability and evidence for life at three desert field sites. Although experimental in

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

    Science.gov (United States)

    Kobelski, A.; ALMA Solar Development Team

    2016-04-01

    The Atacama Large Millimeter/Submillimeter Array (ALMA) is a joint North American, European, and East Asian project that opens the mm-sub mm 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). It is located in the Atacama desert in northern Chile at an elevation of 5000 m. 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.

  18. 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...

  19. 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.

  20. 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.

  1. Solar Simulations for the Atacama Large Millimeter Observatory Network

    OpenAIRE

    Wedemeyer, Sven; Bastian, Tim; 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 collabo...

  2. 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.

  3. 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.

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

    OpenAIRE

    Kamazaki, T.; Okumura, S. K.; 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 con...

  5. The Optical/Infrared Astronomical Quality of High Atacama Sites. I. Preliminary Results of Optical Seeing

    Science.gov (United States)

    Giovanelli, Riccardo; Darling, Jeremy; Sarazin, Marc; Yu, Jennifer; Harvey, Paul; Henderson, Charles; Hoffman, William; Keller, Luke; Barry, Don; Cordes, James; Eikenberry, Stephen; Gull, George; Harrington, Joseph; Smith, J. D.; Stacey, Gordon; Swain, Mark

    2001-07-01

    The region surrounding the Llano de Chajnantor, a high-altitude plateau in the Atacama Desert in northern Chile, has caught the attention of the astronomical community for its potential as an observatory site. Combining high elevation and extremely low atmospheric water content, the Llano has been chosen as the future site of the Atacama Large Millimeter Array. We have initiated a campaign to investigate the astronomical potential of the region in the optical/infrared. Here we report on an aspect of our campaign aimed at establishing a seeing benchmark to be used as a reference for future activities in the region. After a brief description of the region and its climate, we describe the results of an astronomical seeing campaign, carried out with a Differential Image Motion Monitor that operates at 0.5 μm wavelength. The seeing at the Llano altitude of 5000 m, measured over 7 nights in 1998 May, yielded a median FWHM of 1.1". However, the seeing decreased to 0.7" at a modest 100 m gain above the plateau (Cerro Chico), as measured over 38 nights spread between 1998 July and 2000 October. Neither of these represents the best seeing expected in the region; the set of measurements provides a reference base for simultaneous dual runs at Cerro Chico and at other sites of interest in the region, currently underway. A comparison between simultaneous measurements at Cerro Chico and Cerro Paranal indicates that the seeing at Cerro Chico is about 12% better than that at Paranal. The percentage of optically photometric nights in the Chajnantor region is about 60%, while that of nights useful for astronomical work is near 80%.

  6. Shallow water heterobranch sea slugs (Gastropoda: Heterobranchia) from the Región de Atacama, northern Chile.

    Science.gov (United States)

    Araya, Juan Francisco; Valdés, Ángel

    2016-01-01

    The coast of northern Chile has been sparsely studied in regards to its invertebrate fauna, with just a few works reviewing the distribution of local mollusks. This work presents a survey of the shallow water heterobranch sea slugs currently occurring around the port of Caldera (27 °S), in the Región de Atacama, northern Chile. Eight species of sea slugs were found in this study: Aplysiopsis cf. brattstroemi (Marcus, 1959), Baptodoris peruviana (d'Orbigny, 1837), Diaulula variolata (d'Orbigny, 1837), Doris fontainii d'Orbigny, 1837, Onchidella marginata (Couthouy in Gould, 1852), Phidiana lottini (Lesson, 1831), Tyrinna delicata (Abraham, 1877) and the new species Berthella schroedli sp. nov., described herein. All of the species found in the area are endemic to South America, having distributions in the southeastern Pacific and South Atlantic Oceans, from Ancash, Perú to Peninsula Valdés, Argentina, and two of them represent species which are endemic to the Chilean coasts (Aplysiopsis cf. brattstroemi and Berthella schroedli). The finding of a previously undescribed species emphasizes the need of further surveys, particularly in subtidal and deeper waters, in order to improve the knowledge on this neglected fauna in Atacama. PMID:27168975

  7. Shallow water heterobranch sea slugs (Gastropoda: Heterobranchia) from the Región de Atacama, northern Chile

    Science.gov (United States)

    Valdés, Ángel

    2016-01-01

    The coast of northern Chile has been sparsely studied in regards to its invertebrate fauna, with just a few works reviewing the distribution of local mollusks. This work presents a survey of the shallow water heterobranch sea slugs currently occurring around the port of Caldera (27 °S), in the Región de Atacama, northern Chile. Eight species of sea slugs were found in this study: Aplysiopsis cf. brattstroemi (Marcus, 1959), Baptodoris peruviana (d’Orbigny, 1837), Diaulula variolata (d’Orbigny, 1837), Doris fontainii d’Orbigny, 1837, Onchidella marginata (Couthouy in Gould, 1852), Phidiana lottini (Lesson, 1831), Tyrinna delicata (Abraham, 1877) and the new species Berthella schroedli sp. nov., described herein. All of the species found in the area are endemic to South America, having distributions in the southeastern Pacific and South Atlantic Oceans, from Ancash, Perú to Peninsula Valdés, Argentina, and two of them represent species which are endemic to the Chilean coasts (Aplysiopsis cf. brattstroemi and Berthella schroedli). The finding of a previously undescribed species emphasizes the need of further surveys, particularly in subtidal and deeper waters, in order to improve the knowledge on this neglected fauna in Atacama.

  8. 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.

  9. Coast Guard

    International Nuclear Information System (INIS)

    This paper testifies that water pollution by oil remains significant, and noncompliance with federal regulations to prevent oil pollution continues to be great in the four ports GAO visited. Additionally, the impact of the Coast Guard's efforts to reduce oil spill in unknown because the agency does not compile and analyze inspection and spill data needed to make this determination. Further, the Coast Guard has not been inspecting portions of pipes that transport oil between docks and storage tanks. Coast Guard officials now acknowledge this responsibility

  10. 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.

  11. 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...

  12. Early performance of Olea europaea cv. Arbequina, Picual and Frantoio in the southern Atacama Desert

    Directory of Open Access Journals (Sweden)

    Freddy Mora

    2008-01-01

    Full Text Available The cultivars Arbequina, Picual and Frantoio of Olea europaea are cultivated in severalMediterranean countries. In 1999, these cultivars were planted at three locations in the region of Coquimbo,an arid, Mediterranean-like area in Chile. A generalized linear modeling approach was used in view of thenon-normal distribution of the agronomic data sets. Fruit yield (harvests of 2002-2003, precocity (2002 andtree survival (after four growing seasons differed significantly between the cultivars. Arbequina and Picualhad a positive effect on the yield. Picual was the earliest cultivar at two sites. The survival rate of Frantoio washigh at the three sites (90-100%, as opposed to Picual (56-83%. The approach of Generalized Linear Modelswas particularly useful where the assumption of normality was not satisfied. The selection of cultivars ispromising in this arid region of Chile, while the success will depend on the selection of well-adapted genotypesto a particular location.

  13. Changes in the soil C cycle at the arid-hyperarid transition in the Atacama Desert

    Science.gov (United States)

    Ewing, S.A.; Macalady, J.L.; Warren-Rhodes, K.; McKay, C.P.; Amundson, Ronald

    2008-01-01

    We examined soil organic C (OC) turnover and transport across the rainfall transition from a biotic, arid site to a largely abiotic, hyperarid site. With this transition, OC concentrations decrease, and C cycling slows precipitously, both in surface horizons and below ground. The concentration and isotopic character of soil OC across this transition reflect decreasing rates of inputs, decomposition, and downward transport. OC concentrations in the arid soil increase slightly with depth in the upper meter, but are generally low and variable (???0.05%; total inventory of 1.82 kg m-2); OC-??14C values decrease from modern (+7???) to very 14C-depleted (-966???) with depth; and OC-??13C values are variable (-23.7??? to -14.1???). Using a transport model, we show that these trends reflect relatively rapid cycling in the upper few centimeters, and spatially variable preservation of belowground OC from root inputs, possibly during a previous, wetter climate supporting higher soil OC concentrations. In the driest soil, the OC inventory is the lowest among the sites (0.19 kg m-2), and radiocarbon values are 14C-depleted (-365??? to -696???) but show no trend with depth, indicating belowground OC inputs and long OC residence times throughout the upper meter (104 y). A distinct depth trend in ??13C values and OC/ON values within the upper 40 cm at the driest site may reflect photochemical alteration of organic matter at the soil surface, combined with limited subsurface decomposition and downward transport. We argue that while root inputs are preserved at the wetter sites, C cycling in the most hyperarid soil occurs through infrequent, rapid dissolved transport of highly photodegraded organic matter during rare rain events, each followed by a pulse of decomposition and subsequent prolonged drought. These belowground inputs are likely a primary control on the character, activity, and depth distribution of small microbial populations. While the lack of water is the dominant control on C cycling, very low C/N ratios of organic matter suggest that when rainfall occurs, hyperarid soils are effectively C limited. The preservation of fossil root fragments in the sediment beneath the driest soil indicates that wetter climate conditions preceded formation of this soil, and that vadose zone microbial activity has been extremely limited for the past 2 My. Copyright 2008 by the American Geophysical Union.

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

    OpenAIRE

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

    2012-01-01

    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 exc...

  15. Isotope hydrology investigation, area of the Salar de Llamara, Atacama Desert, Chile

    International Nuclear Information System (INIS)

    Different applications of environmental isotopes (18O and 2H) in relation with the hydrogeology of a Northern Chilean basin are presented. The investigation was centered specially in the isotopic characterization of springs and rivers, evaporation processes in river, the generation of the floods, infiltration processes in the alluvium fans, and the origin and movement of the groundwater. (author). 5 refs, 12 figs

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

    OpenAIRE

    Arriagada, C.; Roperch, Pierrick; Mpodozis, C.; Fernandez, R

    2006-01-01

    We report paleomagnetic results for 131 sites from the modern forearc of northern Chile (25 degrees S and 28 degrees 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 degrees +/- 21.6 degrees counterclockwise to 52.7 degrees +/- 17 degrees clockwise. Jurassic to Early Cretaceous r...

  17. Arsenic resistant bacteria isolated from arsenic contaminated river in the Atacama Desert (Chile).

    Science.gov (United States)

    Escalante, G; Campos, V L; Valenzuela, C; Yañez, J; Zaror, C; Mondaca, M A

    2009-11-01

    In this study, arsenic resistant bacteria were isolated from sediments of an arsenic contaminated river. Arsenic tolerance of bacteria isolated was carried out by serial dilution on agar plate. Redox abilities were investigated using KMnO4. arsC and aox genes were detected by PCR and RT-PCR, respectively. Bacterial populations were identified by RapID system. Forty nine bacterial strains were isolated, of these, 55 % corresponded to the reducing bacteria, 4% to oxidizing bacteria, 8% presented both activities and in 33% of the bacteria none activity was detected. arsC gene was detected in 11 strains and aox genes were not detected. The activity of arsenic transforming microorganisms in river sediment has significant implications for the behavior of the metalloid. PMID:19779656

  18. 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.

  19. 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.

  20. The Atacama Cosmology Telescope Project: A Progress Report

    OpenAIRE

    Kosowsky, Arthur; Collaboration, for the ACT

    2006-01-01

    The Atacama Cosmology Telescope is a project to map the microwave background radiation at arcminute angular resolution and high sensitivity in three frequency bands over substantial sky areas. Cosmological signals driving such an experiment are reviewed, and current progress in hardware construction is summarized. Complementary astronomical observations in other wavebands are also discussed.

  1. Coast Guard

    International Nuclear Information System (INIS)

    The 11-million gallon Exxon Valdez oil spill highlighted deficiencies in the nation's ability to contain and recover spilled oil. The Oil Pollution Act of 1990 represents a major effort by Congress to address these deficiencies and to clarify the roles and responsibilities of the private sector and the federal government in preventing, preparing for, and responding to oil spills. This report examines the Coast Guard's efforts to avoid unnecessary and wasteful duplication by coordinating with the private sector and others, including federal and state agencies, its plans to buy oil spill response equipment and the new responsibilities the act places on the private sector and the Coast Guard and if these responsibilities call for a shift in emphasis in Coast Guard oil spill response activities

  2. Oxygen-17 anomaly in soil nitrate: A new precipitation proxy for desert landscapes

    Science.gov (United States)

    Wang, Fan; Ge, Wensheng; Luo, Hao; Seo, Ji-Hye; Michalski, Greg

    2016-03-01

    The nitrogen cycle in desert soil ecosystems is particularly sensitive to changes in precipitation, even of relatively small magnitude and short duration, because it is already under water stress. This suggests that desert soils may have preserved past evidence of small variations in continental precipitation. We have measured nitrate (NO3-) concentrations in soils from the Atacama (Chile), Kumtag (China), Mojave (US), and Thar (India) deserts, and stable nitrogen and oxygen isotope (15N, 17O, and 18O) abundances of the soil NO3-. 17O anomalies (Δ17O), the deviations from the mass-independent isotopic fractionation, were detected in soil NO3- from almost all sites of these four deserts. There was a strong negative correlation between the mean annual precipitation (MAP) and soil NO3- Δ17O values (Δ soil 17O NO3). This MAP- Δ soil 17O NO3 correlation advocated Δ soil 17O NO3 as a new precipitation proxy and was then used to assess precipitation changes in southwestern US at the Pliocene-Pleistocene boundary, in South America during the Miocene, and the Sahara Desert in the past 10 kyr using NO3- Δ17O in paleosols or ancient aquifers. Global and the US maps of surface Δ soil 17O NO3 were also projected with available MAP datasets based on the MAP- Δ soil 17O NO3 model.

  3. Coast Guard

    International Nuclear Information System (INIS)

    This paper reports that about 16,000 oil spills involving the release of more than 46 million gallons of oil took place in U.S. navigable waters in 1988; spills at water-front facilities, where vessels load and unload oil, accounted for about half of the oil spilled. While the Coast Guard acknowledges its responsibility for regulating and inspecting waterfront facilities, it efforts in this area have fallen short because it has not been inspecting portions of intrafacility pipes that transport oil between docks and storage tanks. Water pollution and noncompliance with federal oil pollution prevention regulations continue to be high at waterfront facilities. Yet the Coast Guard cannot determine how effective its inspection program has been in reducing the risk of oil spills because information on program results, such as the types, severity, and frequency of deficiencies found by inspectors, is not compiled an linked with information on the causes of oil spills found by investigators. Until the Coast Guard collects this type of information, it will not be in a position to establish measurable goals

  4. Deep seismic structure of the Atacama basin, northern Chile

    Science.gov (United States)

    Schurr, B.; Rietbrock, A.

    2004-06-01

    The Atacama basin is a prominent morphological anomaly in the Central Andean forearc. 3D seismic structure beneath the depression and its surroundings has been determined from local earthquake tomography. Depth maps of P-wave velocity and attenuation (1/Qp) through the lithosphere reveal a rheologically strong (high Qp and vp) lithospheric block beneath the basin, surrounded by weak regions (low Qp and vp) beneath Pre- and Western Cordilleras. The anomalous lithospheric structure appears to bar hot asthenospheric mantle from penetrating trenchward, and hence causes the volcanic front to be deflected by the Salar de Atacama basin. The cold block may also influence the thermal structure of the subducted slab causing reduced Benioff seismicity and less hydration of mantle rocks evident from reduced vp/vs ratios. Seismic data are hard to reconcile with extension and lithospheric thinning as a mechanism for subsidence of the basin. Instead, high strength of the Atacama lithospheric block may contribute to basin formation by focussing deformation and uplift along the block's weak edges.

  5. 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.

  6. GOPHERUS AGASSIZII (Desert Tortoise)

    International Nuclear Information System (INIS)

    GOPHERLTS AGAISSIZII (Desert Tortoise). Predation. A variety of predators, most notably coyotes (Canis Iatrans) and Common Ravens (Corvis corau) have been reported to prey on hatchling desert tortoises (Emst et al. 1994). Turtles of the United States and Canada (Smithsonian Institution Press, Washington, D.C. 578 pp.). Here, we report an observation of a hatchling tortoise, fitted with a radiotransmitter, that was preyed upon by native fire ants (Solenopsis sp.) in the eastern Mojave Desert at Yucca Mountain, Nevada (36 degrees 50 minutes N, 116 degree 25 minutes E). On 8/27/94, tortoise No.9315 (carapace length = 45 mm, age = 5 d) was found alive with eyes, chin, and parts of the head and legs being eaten by ants. The tortoise was alive, but lethargic, and responded little when touched. Eight of 74 other radiomarked hatchlings monitored at Yucca Mountain during 1992-1994 were found dead with fire ants on their carcass 3-7 days after the hatchlings emerged from their nests. It is not known whether those tortoises were killed by ants or were being scavenged when found. While imported fire ants (S. invicta) have long been known to kill hatchling gopher tortoises (G. polyphemus; Mount 1981. J. Alabama Acad. Sci. 52: 71-78), native fire ants have previously not been implicated as predators of desert tortoises. However, only 1 of 75 (or at worst 9 of 75) was killed by fire ants, suggesting that although fire ants do kill hatchlings, they were not important predators on desert tortoises during this study. Tortoise specimens were deposited at the University of California at Berkeley

  7. 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.

  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. 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.

  10. Desarrollo territorial y turismo en San Pedro de Atacama [Chile

    OpenAIRE

    Gutiérrez Valdivia, Blanca Alexandra

    2010-01-01

    En los últimos diez años, San pedro de Atacama ha experimentado un fuerte crecimiento del sector turístico, como también un explosivo auge de emigración hacia la comuna debido a una fuerte oferta y demanda del sector turístico. Esta situación se enmarca dentro de una falta de planificación sostenible que responda a las problemáticas sociales, culturales y ambientales que se han desarrollado en la comuna.

  11. 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.

  12. Origen de las arenas dunares de la región de Copiapó, Desierto de Atacama, Chile

    Directory of Open Access Journals (Sweden)

    Roland Paskoff

    2003-12-01

    Full Text Available Las extensas dunas de la región de Copiapó presentan formas vivas, pero son dunas remanentes ya que su fuente de abastecimiento en arena fresca está agotada. Según algunos autores, sus arenas habrían provenido por deflación de los depósitos de playa de las amplias terrazas marinas solevantadas que caracterizan la franja costera entre el río Copiapó y Caldera. Antecedentes sedimentológicos no confirman esta interpretación y sugieren un origen fluvial para las arenas. Éstas podrían provenir de formaciones detríticas acumuladas en el Neógeno cerca de sus desembocaduras por el río Copiapó y las quebradas situadas inmediatamente al norteOrigin of sand dunes in the Copiapó region, Atacama Desert, Chile. Extensive areas of active dunes are found in the Copiapó region. However, their sand supply is presently depleted. It has been proposed that deflated uplifted marine terraces of the coastal belt between the Copiapó River and Caldera were the source of the dune sand. Such a hypothesis is not supported by sedimentologic data, which suggest a fluvial origin for the aeolian sands. They could be related to Neogene alluvial accumulations built up at the mouth of the Copiapó River and the ephemeral streams located to the north of it

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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

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

    OpenAIRE

    Nielsen, Axel E.; José Berenguer; Cecilia Sanhueza

    2006-01-01

    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 directamen...

  19. Karst evolution in the Cordillera de la Sal (Atacama, Chili)

    Science.gov (United States)

    de Waele, J.; Forti, P.; Picotti, V.; Zini, L.; Cucchi, F.; Brook, G.

    2009-04-01

    Rock salt composed of halite is at least three orders of magnitude more soluble than limestone. Because of this very high solubility rock salt rarely crops out extensively at the surface and is readily dissolved leaving insoluble residue (mainly clays and marls). Rock salt can only survive at the surface where climate is extremely arid and normally displays a large set of typical solution morphologies similar to those developed on limestone. Solution of rock salt also leads to the formation of underground caves several km long. Close to the village of San Pedro de Atacama, North of the Salar de Atacama basin, there is an important NNE-SSW trending elongated anticlinal ridge composed of Oligo-Miocene evaporitic rocks known under the name Cordillera de la Sal. The thick salt beds of this ridge, even in this hyperarid climate (mean annual rainfall is below 20 mm/y and there may be no rain for several years), have been karstified by occasional rains and have a well developed surface karst geomorphology with extremely sharp rillenkarren often isolating salt pinnacles of up to 15 m in height. During the past 10 years interesting salt caves have been discovered in these halite beds and a detailed morphological study has been carried out both at the surface and in the most important caves with the aim of understanding the mechanisms responsible for their formation and evolution. Sixteen wood and bone fragments from the ceilings of caves and from diamictons in passages have been AMS radiocarbon dated, allowing us to determine when the cave systems formed and when the major sediment units were emplaced. In fact, cave formation appears to have been very rapid, with development of huge cave passages in salt (more than 10 m wide and 30 m high) in less than 2,000 years. Moreover, detailed surveys of cave morphology (e.g. meanders, erosion benches) and sediments (diamictons) suggest that the caves were formed by short-lived flash floods, probably produced by single extreme

  20. 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.

  1. Paleohydrologic evolution and geochemical dynamics of cumulative supergene metal enrichment at La Escondida, Atacama Desert, northern Chile

    Science.gov (United States)

    Alpers, C.N.; Brimhall, G.H.

    1989-01-01

    Quantitative limonite mapping within the leached capping of the porphyry copper deposit at La Escondida, Chile, permits reconstruction of the paleohydrologic and chemical evolution of a well-developed supergene ore-forming system. The mineralogy, textures, and relative abundance of supergene limonite minerals (hematite, goethite, and jarosite) are used to reconstruct the former ratio of pyrite to chalcocite and the preoxidation copper grade based on empirical limonite sulfide correlations. Evidence for cumulative downward enrichment in vertical profiles through leached capping allows quantitative analysis of chemical mass balance in dynamic supergene systems. Slopes of linear regressions for profiles of reconstructed enriched copper grades vs. depth indicate lateral fluxes into or out of a given vertical profile. -from Authors

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

    Czech Academy of Sciences Publication Activity Database

    Vítek, Petr; Ascao, C.; Artieda, O.; Wierzchos, J.

    2016-01-01

    Roč. 408, č. 15 (2016), s. 4083-4092. ISSN 1618-2642 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : hyperspectral imaging * carotenoids * astrobiology * photosynthesis * adaptation strategy * Mars Subject RIV: EE - Microbiology, Virology Impact factor: 3.436, year: 2014

  3. 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

  4. 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.

  5. 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.

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Labelled water in desert survival patterns

    International Nuclear Information System (INIS)

    Tritiated water (3HOH) was used as a tracer to explain, at least in part, the survival of some plants and animals in the Namib Desert. Special attention is given to grass (Stipagrostis sabulicola), a variety of beetles, small desert mammals and the desert ostrich. The potential of doubly-labelled water (3HH18O and 2HH18O) in desert research is briefly mentioned

  16. 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.

  17. 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.

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

    Science.gov (United States)

    Duenner, Rolando; Hasselfield, Matthew; 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; Chervenak, Jay; Calabrese, Erminia; Das, Sudeep; Devlin, Mark J.; Dicker, Simon R.; Doriese, W. Bertrand; Dunkley, Joanna; Essinger-Hileman, Thomas; Moseley, Harvey; Wollack, Ed

    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% or the 90 TB collected by ACT from 2007 to 2010. In 2008 we observed for 136 days, producing a total of 142h of data (11 TB for the 148 GHz band only), with a daily average of 10.5 h of observation. From these, 108.5 h were devoted to 850 sq deg stripe (11.2 h by 9 deg.1) centered on a declination of -52 deg.7, while 175 h were devoted to a 280 square deg stripe (4.5 h by 4 deg.8) 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 h 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-ordered data stream (TOD), is 32 muK square root of s in CMB units. Atmospheric brightness fluctuations constitute the main contaminant in the data and dominate the detector and noise covariance at low frequencies in the TOD. The maps were made by solving the lease squares problem using the Preconditioned Conjugate Gradient method, incorporating the details of the detector and noise correlations. Cross-correlation with WMAP sky maps as well as analysis from simulations reveal the our maps are unbiased at 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.

  19. Mirror Illumination and Spillover Measurements of the Atacama Cosmology Telescope

    Science.gov (United States)

    Gallardo, Patricio; Dunner, Rolando; Wollack, Ed; Jerez-Hanckes, Carlos

    2012-01-01

    The Atacama Cosmology Telescope (ACT) is a 6 m telescope designed to map the Cosmic Microwave Background (CMB) simultaneously at 145 GHz, 220GHz 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 spmover 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, 1 m W source and a chopper wheel to produce a time-varying signal with a broad heam proflle, 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 plus or minus 0,17m in diameter (95 plus or minus 3% of its geometrical size), while the aperture of the secondary yielded 2 plus or minus 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 plus or minus 4,8%. We found that the attenuation outside the primary aperture was -16 plus or minus 2dB, which is below the theoretical expectations, and -22 plus or minus 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 2,24 pW to 188pW.

  20. 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.

  1. THE ATACAMA COSMOLOGY TELESCOPE: DATA CHARACTERIZATION AND MAPMAKING

    International Nuclear Information System (INIS)

    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 deg2 stripe (11.2 hr by 9.°1) centered on a declination of –52.°7, while 175 hr were devoted to a 280 deg2 stripe (4.5 hr by 4.°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 μK√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.

  2. Numerical taxonomy of moderately halophilic gram-positive cocci isolated from the Salar de Atacama (Chile).

    Science.gov (United States)

    Valderrama, M J; Prado, B; del Moral, A; Ríos, R; Ramos-Cormenzana, A; Campos, V

    1991-06-01

    A taxonomic study has been carried out on 22 strains of moderately halophilic motile cocci isolated from the Salar de Atacama (Chile). The 112 phenotypic tests were analyzed by numerical taxonomy using SSM coefficient and the unweighted pair group method of association (UPGMA). At the 67% similarity level, two phenons were obtained: phenon A included 11 strains and phenon B, 11 strains too, whereas the six reference strains did not cluster within these two phenons. These results suggest that moderately halophilic cocci with different phenotypic characteristics from previously described species can be isolated from the hypersaline habitat Salar de Atacama. PMID:1867776

  3. 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...

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

    OpenAIRE

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

    2015-01-01

    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 north...

  5. 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...

  6. Classification of thermophilic actinobacteria isolated from arid desert soils, including the description of Amycolatopsis deserti sp. nov.

    Science.gov (United States)

    Busarakam, Kanungnid; Brown, Ros; Bull, Alan T; Tan, Geok Yuan Annie; Zucchi, Tiago D; da Silva, Leonardo José; de Souza, Wallace Rafael; Goodfellow, Michael

    2016-02-01

    The taxonomic position of 26 filamentous actinobacteria isolated from a hyper-arid Atacama Desert soil and 2 from an arid Australian composite soil was established using a polyphasic approach. All of the isolates gave the diagnostic amplification product using 16S rRNA oligonucleotide primers specific for the genus Amycolatopsis. Representative isolates had chemotaxonomic and morphological properties typical of members of the genus Amycolatopsis. 16S rRNA gene analyses showed that all of the isolates belong to the Amycolatopsis methanolica 16S rRNA gene clade. The Atacama Desert isolates were assigned to one or other of two recognised species, namely Amycolatopsis ruanii and Amycolatopsis thermalba, based on 16S rRNA gene sequence, DNA:DNA relatedness and phenotypic data; emended descriptions are given for these species. In contrast, the two strains from the arid Australian composite soil, isolates GY024(T) and GY142, formed a distinct branch at the periphery of the A. methanolica 16S rRNA phyletic line, a taxon that was supported by all of the tree-making algorithms and by a 100 % bootstrap value. These strains shared a high degree of DNA:DNA relatedness and have many phenotypic properties in common, some of which distinguished them from all of the constituent species classified in the A. methanolica 16S rRNA clade. Isolates GY024(T) and GY142 merit recognition as a new species within the A. methanolica group of thermophilic strains. The name proposed for the new species is Amycolatopsis deserti sp. nov.; the type strain is GY024(T) (=NCIMB 14972(T) = NRRL B-65266(T)). PMID:26809280

  7. 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.

  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. 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.

  10. 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...

  11. 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

  12. Interactions between basement and cover during the evolution of the Salar de Atacama Basin, northern Chile

    OpenAIRE

    Nelson Muñoz; Reynaldo Charrier; Teresa Jordan

    2002-01-01

    ABSTRACT A reinterpretation of the structural style on the eastern Cordillera Domeyko and the adjacent Salar de Atacama Basin reveals the existence of west-dipping, high-angle, thrust-faults extending below the Cordillera Domeyko and Cordón de Lila, resulting from inversion of Cretaceous extensional faults, that transferred west-ward their displacement into the cover, generating fault-propagation and detachment folds. The most conspicuous of these structures is the Cordillera de la Sal. Contr...

  13. 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...

  14. Strategies of desert locust control

    International Nuclear Information System (INIS)

    Full text: The desert locust can infest an area from Mauritania to India and roughly from the Mediterranean to the Equator. Plagues with many swarms of adults and very many bands of hoppers are separated by recessions when most of the locusts are scattered and confined to the arid central belt. Widespread and heavy rain in the recession area may lead to outbreak breeding with 'patches' of hoppers. This may be followed by an upsurge during which successful breeding occurs in areas to which the adults of successive generations migrate. Further population increases leads to a plague. In spite of recent studies, the value of the damage caused by the desert locust is not known and it is not clear whether the control costs balance the prevented damage. But the impact on individual farmers may be devastating. Local crop protection is not feasible and financial compensation is difficult. However, the main importance of the desert locust is 'political' since swarms are dramatic and also migrate between countries. The current strategy is to prevent plagues by control of the outbreak or the early upsurge despite the lack of field evidence that this is effective and theoretical studies that suggest it is not. Moreover, several brief plagues have occurred. The adherence to a preventative strategy, the irregular occurrence of plagues and the fact that even during a plague many countries will escape has led to plague crisis management. During plagues aid, usually in the form of pesticide and aircraft, has been supplied by donors with no adequate assessment of the need or of the capacity of the recipient country to use what is supplied. Much pesticide has remained after plagues, creating a difficult disposal problem. Research and development has concentrated on survey data processing and forecasting with GIS, improved survey and application techniques with GPS, barrier applications with new persistent pesticides, use of mycopesticides and IGRs, and environmental monitoring. The

  15. 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. PMID:26253130

  16. Space Radar Image of Namib Desert in Southern Namib

    Science.gov (United States)

    1999-01-01

    This is a C-band, VV polarization radar image of the Namib desert in southern Namibia, near the coast of South West Africa. The image is centered at about 25 degrees South latitude, 15.5 degrees East longitude. This image was one of the first acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) when it was taken on orbit 4 from the shuttle Endeavour on April 9, 1994. The area shown is approximately 78 kilometers by 20 kilometers. The dominant features in the image are complex sand dune patterns formed by the prevailing winds in this part of the Namib desert. The Namib desert is an extremely dry area formed largely because of the influence of the cold Benguela ocean current that flows northward along the coast of Namibia. The bright areas at the bottom of the image are exposed outcrops of Precambrian rocks. This extremely barren area is a region rich in diamonds that through the centuries have washed down from the mountains. The town of Luderitz is located just to the south of the area shown. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Aumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia

  17. Deserts

    DEFF Research Database (Denmark)

    Graulund, Rune

    2016-01-01

    examines: •Key debates within the field, including postcolonial studies, gender, sexuality and visual culture •Historical and cultural contexts, tracing the evolution of travel writing across time and over cultures •Different styles, modes and themes of travel writing, from pilgrimage to tourism •Imagined......As many places around the world confront issues of globalization, migration and postcoloniality, travel writing has become a serious genre of study, reflecting some of the greatest concerns of our time. Encompassing forms as diverse as field journals, investigative reports, guidebooks, memoirs......, 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. 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...

  19. 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...

  20. Rural childhoods in Egypt's desert lands

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine

    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......’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...

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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...

  7. 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.

  8. 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...

  9. 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...

  10. Desert National Wildlife Range Wilderness study summary

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a summary of a wilderness study done of the Desert National Wildlife Range pursuant to the Wilderness Act of 1964. It provides information as to...

  11. 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.

  12. 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

  13. MARS DESERT RESEARCH STATION: CREW 138

    OpenAIRE

    Roman-Gonzalez, Avid; Saab, Bechara; Berger, Jay; hoyt, johanna; Urquhart, Jimmy; guined, jamie

    2015-01-01

    Crew 138 was comprised of a team of highly-skilled professionals with varied backgrounds who were selected by the Mars Society to undertake a two-week interdisciplinary expedition at the Mars Desert Research Station near Hanksville, Utah. The Crew's activities ranged in scope from preparing operational handbooks and checklists for the Mars Desert Research Station, performing hardware and logistical evaluations for future research at MDRS, an analysis of Google Earth as a tool for geological f...

  14. Physiological Conjunction of Allelochemicals and Desert Plants

    OpenAIRE

    Yosef Friedjung, Avital; Choudhary, Sikander Pal; Dudai, Nativ; Rachmilevitch, Shimon

    2013-01-01

    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...

  15. 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.

  16. 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)

  17. Miocene-Quaternary structural evolution of the Uyuni-Atacama region, Andes of Chile and Bolivia

    OpenAIRE

    Tibaldi, A.; Università degli Studi di Milano-Bicocca; Corazzato, C.; Università degli Studi di Milano-Bicocca; Rovida, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia

    2008-01-01

    We describe the Miocene-Quaternary geological-structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognised four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E-W direction of shortening in the northern part of the studied area and a WNW-ESE shortening in the southern part. Th...

  18. Processes of lithium chlorides purification from Salar de Atacama concentrated brines

    International Nuclear Information System (INIS)

    The results of research carried out to obtain lithium chloride, as a suitable electrolyte for the production of high purity lithium metal are presented. Concentrated lithium chloride brines from Salar de Atacama have been used as starting materials. The studied process requires the reduction of the boron content in the brines to levels below 5 ppm, followed by a crystallization process to obtain a crystallized lithium chloride. The elimination of the magnesium chloride co-crystallized with the lithium chloride, is achieved by a complementary washing step and the lixiviation of the impure LiCl crystals with ethanol. (author)

  19. Estrategias readaptativas en Atacama: la arriería mulera colonial1

    OpenAIRE

    T., Cecilia Sanhueza

    2014-01-01

    Introducción La arriería indígena comenzó a desarrollarse en Atacama durante la segunda mitad del siglo xvi y parece haber adquirido, tempranamente, un papel de importancia para la población local entre las alternativas de participación en los mercados coloniales y como medio de acceso a metálico o circulante. El tráfico de productos regionales –principalmente marinos– hacia los centros urbanos y mineros altiplánicos, ha sido descrito por los cronistas como una de las principales actividades ...

  20. The Atacama Cosmology Telescope: Evidence for Dark Energy from the CMB Alone

    CERN Document Server

    Sherwin, Blake D; Das, Sudeep; Appel, John W; Bond, J Richard; Carvalho, C Sofia; Devlin, Mark J; Dunner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W; 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; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Reese, Erik D; Schmitt, Benjamin L; Sehgal, Neelima; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Visnjic, Katerina; 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 $\\Omega_\\Lambda$ confirms other measurements from supernovae, galaxy clusters and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool.

  1. The Atacama Cosmology Telescope: Calibration with the Wilkinson Microwave Anisotropy Probe Using Cross-Correlations

    Science.gov (United States)

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

    2011-01-01

    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 mapmaking 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 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.

  2. The First Multichroic Polarimeter Array on the Atacama Cosmology Telescope: Characterization and Performance

    Science.gov (United States)

    Ho, S. P.; Pappas, C. G.; Austermann, J.; Beall, J. A.; Becker, D.; Choi, S. K.; Datta, R.; Duff, S. M.; Gallardo, P. A.; Grace, E.; Hasselfield, M.; Henderson, S. W.; Hilton, G. C.; Hubmayr, J.; Koopman, B. J.; Lanen, J. V.; Li, D.; McMahon, J.; Nati, F.; Niemack, M. D.; Niraula, P.; Salatino, M.; Schillaci, A.; Schmitt, B. L.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Ward, J. T.; Wollack, E. J.; Vavagiakis, E. M.

    2016-03-01

    The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization sensitive receiver for the 6-m Atacama Cosmology Telescope (ACT) and measures the small angular scale polarization anisotropies in the cosmic microwave background (CMB). The full focal plane is composed of three detector arrays, containing over 3000 transition edge sensors (TES detectors) in total. The first two detector arrays, observing at 146 GHz, were deployed in 2013 and 2014, respectively. The third and final array is composed of multichroic pixels sensitive to both 90 and 146 GHz and saw first light in February 2015. Fabricated at NIST, this dichroic array consists of 255 pixels, with a total of 1020 polarization sensitive bolometers and is coupled to the telescope with a monolithic array of broad-band silicon feedhorns. The detectors are read out using time-division SQUID multiplexing and cooled by a dilution refrigerator at 110 mK. We present an overview of the assembly and characterization of this multichroic array in the lab, and the initial detector performance in Chile. The detector array has a TES detector electrical yield of 85 %, a total array sensitivity of less than 10 \\upmu K√{s} , and detector time constants and saturation powers suitable for ACT CMB observations.

  3. The Bulimulidae (Mollusca: Pulmonata) from the Región de Atacama, northern Chile.

    Science.gov (United States)

    Araya, Juan Francisco

    2015-01-01

    The bulimulid genus Bostryx Troschel, 1847 is the most species-rich genus of land snails found in Chile, with the majority of its species found only in the northern part of the country, usually in arid coastal zones. This genus has been sparsely studied in Chile and there is little information on their distribution, diversity or ecology. Here, for the first time, a formal analysis of the diversity of bulimulids in the Región de Atacama, northern Chile, is reported. Of the seventeen species recorded for the area, most of them were efectively found in the field collections and one record was based on literature. Five taxa are described as new: Bostryx ancavilorum sp. nov., Bostryx breurei sp. nov., Bostryx calderaensis sp. nov., Bostryx ireneae sp. nov. and Bostryx valdovinosi sp. nov., and the known geographic distribution of seven species is extended. Results reveal that the Región de Atacama is the richest region in terrestrial snails in Chile, after the Juan Fernández Archipelago. All of the terrestrial molluscan species occurring in the area are endemic to Chile, most of them with restricted geographic distributions along the coastal zones, and none of them are currently protected by law. Further sampling in northern Chile will probably reveal more snail species to be discovered and described. PMID:26587346

  4. EL LIDERAZGO ÉTNICO EN ATACAMA, ALTOS DE ARICA, TACNA Y TARATA (SIGLO XVIII

    Directory of Open Access Journals (Sweden)

    Jorge Hidalgo Lehuedé

    2004-09-01

    Full Text Available En este artículo realizamos un análisis comparado de las dinámicas y transformaciones que experimentó el liderazgo étnico de los cacicazgos de Atacama, Codpa, Altos de Arica, Tacna y Tarata, durante el siglo XVIII. Sostenemos, además, que las dinámicas del liderazgo étnico se ajustaron, más que a proyectos comunitarios, a estrategias familiares. Estas últimas debieron enfrentarse a condiciones sociales de posibilidad en las que se entremezclaron las limitaciones, las demandas y las oportunidades que les ofrecía el campo social colonialIn this article we will realice a comparative analysis of the dynamic and transformations that experienced the ethnic leadership of the Atacama, Codpa, Tacna and Tarata chiefdom, during 18th century. We support, beside, that the ethnic leadership dynamics adjusted more to a family strategy than a communitary project. This family strategy should face a social conditions of possibilities, just a mixture of limitation, demands and opportunities that the colonial society offer them

  5. 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...

  6. 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 ...

  7. Infecção por Enterobius vermicularis em populações agro-pastoris pré-colombianas de San Pedro de Atacama, Chile Enterobius vermicularis infection in pre-Columbian population from San Pedro de Atacama, Chile

    OpenAIRE

    Luiz Fernando Ferreira; Adauto Araujo; Ulisses Confalonieri; Lautaro Nuñez

    1989-01-01

    Enterobius vermicularis eggs were found in human coprolites collected from the archaeological site of San Pedro de Atacama, North of Chile, in occupational layers dated from 1,000 BC. Agricultures and herding were begining at this period of time in this region of South America. The paleoparasitological data amplifies the knowledge about the distribution of human oxyuriasis in Pre-Columbian America.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. Hydrogeology of the lacustrine system of the eastern margin of the Salar the Atacama (Chile); Hidrogeologia del sistema lagunar del margen este del Salar de Atacama (Chile)

    Energy Technology Data Exchange (ETDEWEB)

    Salas, J.; Guimera, J.; Cornella, O.; Aravena, R.; Guzman, E.; Tore, C.; von Igel, W.; Moreno, R.

    2010-07-01

    A hydrogeological conceptual model of the Eastern margin of the Salar de Atacama (Chile) is proposed taking into account climatic, geological, geomorphological, piezometric, chemical and isotopic data. The study establishes the processes that explain the hydrochemical evolution of waters from salty groundwater in the alluvial aquifer located in eastern part of basin until brines at the saline aquifer of the Salar. The main processes associated with this hydrochemical evolution are evaporation and mixing, but water-crust interaction in the discharge areas of the alluvial aquifer associated with the saline wedge also modifies groundwater composition, and plays a role in the dynamics of the evaporitic crusts in the Salar. The existence of low permeability materials near the surface explains the existence of the permanent surface water bodies in the study area. Based on the data collected in the study three different mechanisms are proposed regarding the main sources of water to the lagoons: (1) discharge of saline groundwater from the detrital and volcanic aquifers of the E margin, (2) discharge of surface waters associated to the N area (Burro Muerto channel), and (3) a combination of both previous mechanisms. (Author).

  13. 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.

  14. 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 ...

  15. 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.

  16. Ungaretti and the Invention of the Desert

    OpenAIRE

    Daniel del Percio

    2015-01-01

    The desert is the land of the Profets and its void delimits a space of infinity possibilites. The presence of this space in the italian poetry is considerable. For Giuseppe Ungaretti, a man who was born in the city of Alexandria, in Egypt, the infance was a space delimited by two deserts: the sand and the sea. Both conform in the poet a vision of time and space that the young Ungaretti will discover in the Bergson’s and Nietzsche’s philosophy and as poetry in the most pure italian tradition: ...

  17. 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.

  18. Calibration of vector navigation in desert ants.

    OpenAIRE

    Collett, M; Collett, T. S.; Wehner, R

    1999-01-01

    Desert ants (Cataglyphis sp.) monitor their position relative to the nest using a form of dead reckoning [1] [2] [3] known as path integration (PI) [4]. They do this with a sun compass and an odometer to update an accumulator that records their current position [1]. Ants can use PI to return to the nest [2] [3]. Here, we report that desert ants, like honeybees [5] and hamsters [6], can also use PI to approach a previously visited food source. To navigate to a goal using only PI information, a...

  19. 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

  20. 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.

  1. Use of a Novel Rover-mounted Fluorescence Imager and Fluorescent Probes to Detect Biological Material in the Atacama Desert in Daylight

    Science.gov (United States)

    Weinstein, S.; Pane, D.; Warren-Rhodes, K.; Cockell, C.; Ernst, L. A.; Minkley, E.; Fisher, G.; Emani, S.; Wettergreen, D. S.; Wagner, M.

    2005-01-01

    We have developed an imaging system, the Fluorescence Imager (FI), for detecting fluorescence signals from sparse microorganisms and biofilms during autonomous rover exploration. The fluorescence signals arise both from naturally occurring chromophores, such as chlorophyll of cyanobacteria and lichens, and from fluorescent probes applied to soil and rocks. Daylight imaging has been accomplished by a novel use of a high-powered flashlamp synchronized to a CCD camera. The fluorescent probes are cell permanent stains that have extremely low intrinsic fluorescence (quantum yields less than 0.01) and a large fluorescence enhancement (quantum yields greater than 0.4) when bound to the target. Each probe specifically targets either carbohydrates, proteins, nucleic acids or membrane lipids, the four classes of macromolecules found in terrestrial life. The intent of the probes is to interrogate the environment for surface and endolithic life forms.

  2. 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.

  3. Taxonomic study of extreme halophilic archaea isolated from the "Salar de Atacama", Chile.

    Science.gov (United States)

    Lizama, C; Monteoliva-Sánchez, M; Prado, B; Ramos-Cormenzana, A; Weckesser, J; Campos, V

    2001-11-01

    A large number of halophilic bacteria were isolated in 1984-1992 from the Atacama Saltern (North of Chile). For this study 82 strains of extreme halophilic archaea were selected. The characterization was performed by using the phenotypic characters including morphological, physiological, biochemical, nutritional and antimicrobial susceptibility test. The results, together with those from reference strains, were subjected to numerical analysis, using the Simple Matching (S(SM)) coefficient and clustered by the unweighted pair group method of association (UPGMA). Fifteen phena were obtained at an 70% similarity level. The results obtained reveal a high diversity among the halophilic archaea isolated. Representative strains from the phena were chosen to determine their DNA base composition and the percentage of DNA-DNA similarity compared to reference strains. The 16S rRNA studies showed that some of these strains constitutes a new taxa of extreme halophilic archaea. PMID:11822685

  4. Design and Deployment of a Multichroic Polarimeter Array on the Atacama Cosmology Telescope

    CERN Document Server

    Datta, R; Beall, J A; Becker, D; Coughlin, K P; Duff, S M; Gallardo, P A; Grace, E; Hasselfield, M; Henderson, S W; Hilton, G C; Ho, S P; Hubmayr, J; Koopman, B J; Lanen, J V; Li, D; McMahon, J; Munson, C D; Nati, F; Niemack, M D; Page, L; Pappas, C G; Salatino, M; Schmitt, B L; Schillaci, A; Simon, S M; Staggs, S T; Stevens, J R; Vavagiakis, E M; Ward, J T; Wollack, E J

    2015-01-01

    We present the design and the preliminary on sky performance with respect to beams and pass-bands of a multichroic polarimeter array covering the 90 and 146 GHz Cosmic Microwave Background (CMB) bands and its enabling broadband optical system recently deployed on the Atacama Cosmology Telescope (ACT). The constituent pixels are feedhorn-coupled multichroic polarimeters fabricated at NIST. This array is coupled to the ACT telescope via a set of three silicon lenses incorporating novel broad-band metamaterial anti-reflection coatings. This receiver represents the first multichroic detector array deployed for a CMB experiment and paves the way for the extensive use of multichroic detectors and broadband optical systems in the next generation of CMB experiments.

  5. Design and Deployment of a Multichroic Polarimeter Array on the Atacama Cosmology Telescope

    Science.gov (United States)

    Datta, R.; Austermann, J.; Beall, J. A.; Becker, D.; Coughlin, K. P.; Duff, S. M.; Gallardo, P. A.; Grace, E.; Hasselfield, M.; Henderson, S. W.; Hilton, G. C.; Ho, S. P.; Hubmayr, J.; Koopman, B. J.; Lanen, J. V.; Li, D.; McMahon, J.; Munson, C. D.; Nati, F.; Niemack, M. D.; Page, L.; Pappas, C. G.; Salatino, M.; Schmitt, B. L.; Schillaci, A.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Vavagiakis, E. M.; Ward, J. T.; Wollack, E. J.

    2016-03-01

    We present the design and the preliminary on-sky performance with respect to beams and passbands of a multichroic polarimeter array covering the 90 and 146 GHz cosmic microwave background bands and its enabling broad-band optical system recently deployed on the Atacama Cosmology Telescope (ACT). The constituent pixels are feedhorn-coupled multichroic polarimeters fabricated at NIST. This array is coupled to the ACT telescope via a set of three silicon lenses incorporating novel broad-band metamaterial anti-reflection coatings. This receiver represents the first multichroic detector array deployed for a CMB experiment and paves the way for the extensive use of multichroic detectors and broad-band optical systems in the next generation of CMB experiments.

  6. The Atacama Cosmology Telescope: Calibration with the Wilkinson Microwave Anisotropy Probe Using Cross-Correlations

    Science.gov (United States)

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

    2011-01-01

    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 mapmaking 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 < I < 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.

  7. Caso exitoso eficiencia energética: Hotel Explora: San Pedro de Atacama

    OpenAIRE

    Banco Interamericano de Desarrollo (BID); Fundación Chile

    2012-01-01

    Este documento presenta el caso exitoso de mejora de la eficiencia energética en el Hotel Explora en San Pedro de Atacama. La empresa, mediante los aportes del BID-FOMIN - a través del "Programa de promoción de oportunidades de energías limpias" - ejecutado por Fundación Chile, logró ahorros anuales de 60 millones, un retorno de la inversión de 1 a 3 años, y un ahorro de emisiones de CO2 de 140 toneladas al año. En el documento se explican los pormenores financieros y técnicos del proyecto....

  8. 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.

  9. The Atacama Cosmology Telescope: a measurement of the primordial power spectrum

    CERN Document Server

    Hlozek, Renée; Addison, Graeme; Appel, John William; Bond, J Richard; Carvalho, C Sofia; Das, Sudeep; Devlin, Mark; Dünner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph; Gallardo, Patricio; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D; Hughes, John P; Irwin, Kent; Klein, Jeff; Kosowsky, Arthur; Marriage, Tobias A; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D; Nolta, Michael R; Page, Lyman; Parker, Lucas; Partridge, Bruce; Rojas, Felipe; Sehgal, Neelima; Sherwin, Blake; Sievers, Jon; Spergel, David; Staggs, Suzanne; Swetz, Daniel; Switzer, Eric; Thornton, Robert; Wollack, Ed

    2011-01-01

    We present constraints on the primordial power spectrum of adiabatic fluctuations using data from the 2008 Southern Survey of the Atacama Cosmology Telescope (ACT). The angular resolution of ACT provides sensitivity to scales beyond \\ell = 1000 for resolution of multiple peaks in the primordial temperature power spectrum, which enables us to probe the primordial power spectrum of adiabatic scalar perturbations with wavenumbers up to k \\simeq 0.2 Mpc^{-1}. We find no evidence for deviation from power-law fluctuations over two decades in scale. Matter fluctuations inferred from the primordial temperature power spectrum evolve over cosmic time and can be used to predict the matter power spectrum at late times; we illustrate the overlap of the matter power inferred from CMB measurements (which probe the power spectrum in the linear regime) with existing probes of galaxy clustering, cluster abundances and weak lensing constraints on the primordial power. This highlights the range of scales probed by current measur...

  10. 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...

  11. Cenozoic subsurface stratigraphy and structure of the Salar de Atacama Basin, northern Chile

    Science.gov (United States)

    Jordan, T. E.; Mpodozis, C.; Muñoz, N.; Blanco, N.; Pananont, P.; Gardeweg, M.

    2007-02-01

    Sequence mapping of industry seismic lines and their correlation to exposed stratigraphic formations enable a description of the evolution of the nonmarine Salar de Atacama Basin. This major tectonic basin, located in the present-day forearc of the northern Chilean Andes, was first defined topographically by late Cretaceous inversion of the Jurassic-early Cretaceous extensional Tarapacá backarc Basin. Inversion led to both the uplift of the Cordillera de Domeyko and subsidence of the Salar de Atacama Basin along its eastern flank. The basin evolved from a continental backarc in the Cretaceous and Paleogene to a forearc tectonic setting during the Neogene. The principal causes of basin-scale tectonic subsidence include late Cretaceous and earliest Paleocene shortening and Oligocene-early Miocene localized extension. The basin was not completely filled by late Cretaceous (Purilactis Group, sequence G) and Paleocene (sequence H) strata, and its empty space persisted through the Cenozoic. Eocene deformation caused long-wavelength rotation of a deeply weathered surface, generating an erosional unconformity across which coarse clastic strata accumulated (sequence J). Oligocene-early Miocene normal faulting, perhaps in a transtensional environment, repositioned the western basin margin and localized hangingwall subsidence, leading to the accumulation of thousands of meters of evaporitic strata (sequence K, Paciencia Group). By the close of the early Miocene, shortening resumed, first uplifting the intrabasinal Cordillera de la Sal and later generating Pliocene blind reverse faults within the topographically lowest part of the basin. Unequal deposition and tilting across the nascent Cordillera de la Sal induced diapirism of the Paciencia Group halite. In combination, inherited accommodation space and new tectonic subsidence, plus local salt-withdrawal subsidence, shaped the distribution of Upper Miocene-Recent ignimbrites, evaporites, and clastics (sequence M and Vilama

  12. Evaporation and land surface energy budget at the Salar de Atacama, Northern Chile

    Science.gov (United States)

    Kampf, Stephanie K.; Tyler, Scott W.; Ortiz, Cristián A.; Muñoz, José F.; Adkins, Paula L.

    2005-08-01

    Playa systems are driven by evaporation processes, yet the mechanisms by which evaporation occurs through playa salt crusts are still poorly understood. In this study we examine playa evaporation as it relates to land surface energy fluxes, salt crust characteristics, groundwater and climate at the Salar de Atacama, a 3000 km 2 playa in northern Chile containing a uniquely broad range of salt crust types. Land surface energy budget measurements were taken at eight representative sites on this playa during winter (August 2001) and summer (January 2002) seasons. Measured values of net all-wave radiation were highest at vegetated and rough halite crust sites and lowest over smooth, highly reflective salt crusts. Over most of the Salar de Atacama, net radiation was dissipated by means of soil and sensible heat fluxes. Dry salt crusts tended to heat and cool very quickly, whereas soil heating and cooling occurred more gradually at wetter vegetated sites. Sensible heating was strongly linked to wind patterns, with highest sensible heat fluxes occurring on summer days with strong afternoon winds. Very little energy available at the land surface was used to evaporate water. Eddy covariance measurements could only constrain evaporation rates to within 0.1 mm d -1, and some measured evaporation rates were less than this margin of uncertainty. Evaporation rates ranged from 0.1 to 1.1 mm d -1 in smooth salt crusts around the margin of the salar and from 0.4 to 2.8 mm d -1 in vegetated areas. No evaporation was detected from the rugged halite salt crust that covers the interior of the salar, though the depth to groundwater is less than 1 m in this area. These crusts therefore represent a previously unrecorded end member condition in which the salt crusts form a practically impermeable barrier to evaporation.

  13. Interpersonal violence in prehistoric San Pedro de Atacama, Chile: behavioral implications of environmental stress.

    Science.gov (United States)

    Torres-Rouff, Christina; Costa Junqueira, María Antonietta

    2006-05-01

    The prehistoric population of San Pedro de Atacama lived through periods marked by prosperity and interregional interaction, as well as times of severe drought, social stress, and widespread poverty. A sample of 682 crania was analyzed for evidence of cranial trauma in order to assess changing patterns of interpersonal violence during the occupation of the oasis. It was hypothesized that the level of traumatic injuries in this population would parallel some of the changes seen in the archaeological record. Low fracture rates would be expected in periods of affluence and environmental stability, while periods characterized by environmental extremes and state collapse would yield elevated rates of aggression. This analysis found that rates of trauma escalated from 5.1% (5/99) in the earliest period, to 10.9% (10/92) in the Middle Horizon (AD 600-950). Although it may reflect problems related to increasing population density in the oasis, this increase is surprising, given that the early period witnessed the shift to permanent settlements, and the middle period was one of prosperity and plentiful resource availability. Trauma rates peaked at 35.6% (16/45) in an early Late Intermediate period (AD 950-1400) cemetery, with other Late Intermediate cemeteries demonstrating similarly high rates of traumatic injury. The elevated trauma rates during this period correlate with major droughts, the concentration of settlements on the oasis' east side, fortified structures, and material poverty, all reflected in the archaeological record. As the Late Intermediate waned and environmental conditions improved, trauma concomitantly decreased (7.0%), and remained low throughout the Inka occupation (AD 1400-1532). This indicates that while the Atacama was not peaceful, violence became commonplace only during periods of great social change and resource stress. PMID:16353221

  14. Historical Review of Tsunamigenic Earthquakes on the Jalisco Coast

    Science.gov (United States)

    Castillo, R.; Ramirez-Herrera, M.

    2013-05-01

    This study aims to discuss, interpret and map in a GIS database, historical data gathered from archives, scientific reports and newspapers, of earthquakes generated along the Jalisco and Colima coasts, to achieve a better understanding of epicenters location and the distribution of earthquake damage. Emphasis is placed on earthquakes that caused or may have caused tsunamis. This coastal area runs parallel to the Rivera's plate subduction, along an active convergent margin. The tectonic setting favors the generation of earthquakes with magnitude Ms≥6.5, causing damages locally and regionally. At least five tsunamis (23/02/1875, 03/06/1932, 22/06/1932, 19/06/1995 and 22/01/2003) have originated locally, two of them of great intensity. Historical data are available since the 16th century, but are scarce since this coast had few populated places. Early chronicles from 16th century described populated villages at Bahía de Banderas, Tomatlán and Barra de Navidad, though in the 18th century the western pacific coast of Jalisco (Nueva Galicia) was almost deserted. Between the 18th century and first half of the 20th century, this section of the Pacific coast experienced a slow occupation process, accelerated over the course of the last fifty years. Historical data analysis and GIS database are necessary in order to answer the questions on: 1) which ones were the most intense earthquakes and tsunamis that originated in the area, and 2) what kind of information is available for each one. This information is relevant to earthquake and tsunami hazard assessment and vulnerability of this area.

  15. Life in the Atacama — Year 2: Geologic reconnaissance through long-range roving and implications on the search for life

    OpenAIRE

    Dohm, J.M.; Cabrol, N. A.; Grin, E. A.; Moersch, J.; G. Chong Diaz; Cockell, C; Coppin, P; Fisher, G.; Hock, A. N.; Marinangeli, L.; Minkley, N.; Ori, G.G.; Piatek, J. L.; Warren-Rhodes, K.; Weinstein, S

    2005-01-01

    The Life in the Atacama-2004 project, which included geological, morphological, and mineralogical mapping through combined satellite, field-based, and microscopic perspectives and long-range roving, led to the localization of potential habitats.

  16. 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.

  17. 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

  18. 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%.

  19. 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.

  20. Antioxidant Activity of Sonoran Desert Bee Pollen

    Science.gov (United States)

    Bee products have been consumed by mankind since antiquity and their health benefits are becoming more apparent. Bee pollen (pollen collected by honey bees) was collected in the high intensity ultraviolet (UV) Sonoran desert and was analyzed by the anti-2,2-diphenyl-1-picryhydrazyl (DPPH) assay and...

  1. 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.

  2. 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.

  3. Infecção por Enterobius vermicularis em populações agro-pastoris pré-colombianas de San Pedro de Atacama, Chile Enterobius vermicularis infection in pre-Columbian population from San Pedro de Atacama, Chile

    Directory of Open Access Journals (Sweden)

    Luiz Fernando Ferreira

    1989-01-01

    Full Text Available Enterobius vermicularis eggs were found in human coprolites collected from the archaeological site of San Pedro de Atacama, North of Chile, in occupational layers dated from 1,000 BC. Agricultures and herding were begining at this period of time in this region of South America. The paleoparasitological data amplifies the knowledge about the distribution of human oxyuriasis in Pre-Columbian America.

  4. West Coast Fishing Closures, 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data delineate state and federally managed ocean areas off the West Coast of the United States that are closed to or have restrictions on commercial or...

  5. 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...

  6. 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

  7. 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

  8. The Salar de Atacama Basin: a Subsiding Block within the Western Edge of the Altiplano-Puna Plateau

    OpenAIRE

    Klaus-J. Reutter; Reynaldo Charrier; Hans-J. Götze; B. Schurr; Peter Wigger; Ekkehard Scheuber; Peter Giese; Claus-Dieter Reuther; Sabine Schmidt; Andreas Rietbrock; Guillermo Chong; Arturo Belmonte-Pool

    2006-01-01

    The internally drained Salar de Atacama (SdA) Basin, located in the proximal fore-arc between the present magmatic arc (Western Cordillera) to the east and the North Chilean Precordillera (Cordillera de Domeyko) to the west, represents a prominent morphological anomaly in the Central Andean Plateau. The basin is a post-Incaic feature that developed contemporaneously with the initial plateau uplift. Before 38 Ma, the magmatic arc was positioned in the present-day Precordillera; as a result, th...

  9. Evolution actuelle des phénomènes karstiques dans la Cordillera de la Sal (Atacama, Nord Chili)

    OpenAIRE

    Sesiano, Jean

    2006-01-01

    Des phénomènes karstiques ont été observés sur un massif de sel gemme (halite) dans la Cordillera de la Sal, Atacama, Chili. Au vu de l'aridité des lieux, il semble que ce soit un héritage de périodes plus humides, car ce ne sont plus que des retouches qui affectent actuellement le massif.

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

    International Nuclear Information System (INIS)

    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

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

    OpenAIRE

    Massimo Palme; José Guerra; Sergio Alfaro

    2014-01-01

    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. ...

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

    OpenAIRE

    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 eutrophi...

  13. 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.

  14. 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.

  15. Interactions between basement and cover during the evolution of the Salar de Atacama Basin, northern Chile

    Directory of Open Access Journals (Sweden)

    Nelson Muñoz

    2002-07-01

    Full Text Available ABSTRACT A reinterpretation of the structural style on the eastern Cordillera Domeyko and the adjacent Salar de Atacama Basin reveals the existence of west-dipping, high-angle, thrust-faults extending below the Cordillera Domeyko and Cordón de Lila, resulting from inversion of Cretaceous extensional faults, that transferred west-ward their displacement into the cover, generating fault-propagation and detachment folds. The most conspicuous of these structures is the Cordillera de la Sal. Contractional structures in the Cordillera Domeyko involved a Paleozoic crystalline, volcanic, and sedimentary, uplifted basement. Seismic reflection sections and available surface geology allows to study the interactions between development of the thick-skinned basement structures, sedimentation within the basin, and the thin-skinned deformation in the sedimentary cover. Geometry of the units in the basin continuously modified. Anticline growth above basement thrust-faults locally controlled syn-thrusting sequences, and generated progressive unconformities. Stratigraphic architecture in the basin seems to have been mainly controlled by tectonic activity. Tectonism generated accommodation space, altered base levels, and controlled source areas. The stratigraphy and geometry of the basin deposits resulted mainly from the succession of the following events: local extensional subsidence during the Early to Late Cretaceous, uplift of the Cordillera Domeyko during the latest Cretaceous to Miocene, uplift of the Puna, and subsidence probably caused by flexural response of the lithosphere during thrust-sheet loading, and sediment accumulationRESUMEN Interacciones entre el basamento y la cobertura durante la evolución de la Cuenca del Salar de Atacama, norte de Chile. La reinterpretación del estilo estructural del borde oriental de la Cordillera Domeyko y de la adyacente cuenca del Salar de Atacama, basada en el análisis de la geología de superficie y de perfiles s

  16. Ungaretti and the Invention of the Desert

    Directory of Open Access Journals (Sweden)

    Daniel del Percio

    2015-04-01

    Full Text Available The desert is the land of the Profets and its void delimits a space of infinity possibilites. The presence of this space in the italian poetry is considerable. For Giuseppe Ungaretti, a man who was born in the city of Alexandria, in Egypt, the infance was a space delimited by two deserts: the sand and the sea. Both conform in the poet a vision of time and space that the young Ungaretti will discover in the Bergson’s and Nietzsche’s philosophy and as poetry in the most pure italian tradition: Petrarca and Leopardi. Our proposal is to mark the meaning of this space, mythical and concrete at the same time, in the images of your poetry and in your syntax.

  17. 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.

  18. [A phytosociological interpretation of vegetation from sandy hills of the Peruvian desert].

    Science.gov (United States)

    Galán de Mera, Antonio; Linares Perea, Eliana; Campos de la Cruz, José; Vicente Orellana, José Alfredo

    2011-06-01

    The vegetation of the sandy hills ("lomas") constitutes the main originality of the Peruvian and Chilean desert with a high number of endemics that shapes the vicarious associations. In this work, a phytosociological view of sandy environments of the Peruvian coastal desert is presented. According to the Braun-Blanquet method, we have made up 32 phytosociological inventories and added 138 ones from others authors. In each inventory, we have analyzed its floristic composition and ecological parameters, as altitude, soil and geomorphology. All releves were synthesized in a table to deduce the different associations, higher phytosociological units, and the distribu tion of its flora along the Peruvian coast and the Andean Cordillera. Using the Shannon-Wiener diversity index, the diversity of this flora is discussed making a comparison with historical data about the use of the territory with livestock during pre-Inca and Inca cultures, and Spanish invasion. As a result, two associations from Southern Peru -Nolanetum scaposo-spathulatae and Palauetum camanensis-weberbaueri-, two alliances -Nolanion humifusae from central Peru, and Nolanion spathulatae from the Southern Peru- and a new order -Tetragonio crystallinae-Plantaginetalia limensis- are described. In Nolanetum scaposo-spathulatae, Dictyophragnus englerianus, Leptoglossis lomana, Nolana scaposa, N. spathulata, Palaua velutina and Tetragonia vestita are the main characteristics, while in Palauetum camanensis-weberbaueri association N. scaposa and P. velutina are replaced by Palaua camanensis and P. weberbaueri. Nolanion humifusae alliance integrates species as Geranium limae, Hymenocallis amancaes, Nolana humifusa, N. latipes, Palaua rhombifolia or Villanova oppositifolia. Likewise, Cistanthe weberbaueri, Cryptantha parviflora, Hoffmannseggia miranda, Lupinus mollendoensis, Nolana confinis, N. pallidula, N. scaposa, N. spathulata, Palaua camanensis, P. velutina, P. weberbaueri, Tetragonia vestita and

  19. Path integration in desert ants, Cataglyphis fortis

    OpenAIRE

    Müller, Martin; Wehner, Rüdiger

    1988-01-01

    Foraging desert ants, Cataglyphis fortis, continually keep track of their own posotions relative to home— i.e., integrate their tortuous outbound routes and return home along straight (inbound) routes. By experimentally manipulating the ants' outbound trajectories we show that the ants solve this path integration problem not by performing a true vector summation (as a human navigator does) but by employing a computationally simple approximation. This approximation is characterized by small, b...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. The provenance of Taklamakan desert sand

    Science.gov (United States)

    Rittner, Martin; Vermeesch, Pieter; Carter, Andrew; Bird, Anna; Stevens, Thomas; Garzanti, Eduardo; Andò, Sergio; Vezzoli, Giovanni; Dutt, Ripul; Xu, Zhiwei; Lu, Huayu

    2016-03-01

    Sand migration in the vast Taklamakan desert within the Tarim Basin (Xinjiang Uyghur Autonomous region, PR China) is governed by two competing transport agents: wind and water, which work in diametrically opposed directions. Net aeolian transport is from northeast to south, while fluvial transport occurs from the south to the north and then west to east at the northern rim, due to a gradual northward slope of the underlying topography. We here present the first comprehensive provenance study of Taklamakan desert sand with the aim to characterise the interplay of these two transport mechanisms and their roles in the formation of the sand sea, and to consider the potential of the Tarim Basin as a contributing source to the Chinese Loess Plateau (CLP). Our dataset comprises 39 aeolian and fluvial samples, which were characterised by detrital-zircon U-Pb geochronology, heavy-mineral, and bulk-petrography analyses. Although the inter-sample differences of all three datasets are subtle, a multivariate statistical analysis using multidimensional scaling (MDS) clearly shows that Tarim desert sand is most similar in composition to rivers draining the Kunlun Shan (south) and the Pamirs (west), and is distinctly different from sediment sources in the Tian Shan (north). A small set of samples from the Junggar Basin (north of the Tian Shan) yields different detrital compositions and age spectra than anywhere in the Tarim Basin, indicating that aeolian sediment exchange between the two basins is minimal. Although river transport dominates delivery of sand into the Tarim Basin, wind remobilises and reworks the sediment in the central sand sea. Characteristic signatures of main rivers can be traced from entrance into the basin to the terminus of the Tarim River, and those crossing the desert from the south to north can seasonally bypass sediment through the sand sea. Smaller ephemeral rivers from the Kunlun Shan end in the desert and discharge their sediment there. Both river run

  6. 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...

  7. Biomineralization of carbonates by Marinococcus albus and Marinococcus halophilus isolated from the Salar de Atacama (Chile).

    Science.gov (United States)

    Rivadeneyra, M A; Delgado, G; Soriano, M; Ramos-Cormenzana, A; Delgado, R

    1999-07-01

    We studied the precipitation of carbonates in 17 strains of moderately halophilic, Gram-positive cocci belonging to two species: Marinococcus halophilus and Marinococcus albus, isolated from the Salar de Atacama (Chile). They were cultivated in solid and liquid laboratory media for 42 days at salt concentrations (wt/vol) of 3%, 7.5%, 15%, and 20%. The bioliths precipitated were studied by X-ray diffraction and scanning electron microscopy. M. halophilus formed crystals at each of the salt concentrations, with a maximum number of strains capable of precipitating carbonates at 7.5% and 15% salt concentrations. M. albus did not precipitate at 20% and showed a maximum at 7.5%. This behavior is similar to that of other gram-positive bacteria and differs from that found in gram-negative bacteria. The bioliths precipitated were spherical, generally isolated, with a size of 10-100 microm, varying with salinity. They were of magnesium calcite (CO3 Ca1-x Mgx) with Mg content increasing with increasing salinity and Mg/Ca molar ratio of the culture medium. These results demonstrate the active role played by M. halophilus and M. albus in the precipitation of carbonates. PMID:10387118

  8. 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...

  9. 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 ...

  10. The Atacama Cosmology Telescope: temperature and gravitational lensing power spectrum measurements from three seasons of data

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sudeep [Argonne National Laboratory, 9700 S. Cass Ave., Lemont, IL 60439 (United States); Louis, Thibaut; Calabrese, Erminia; Dunkley, Joanna [Sub-department of Astrophysics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom); Nolta, Michael R.; Bond, J Richard; Hajian, Amir; Hincks, Adam D. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON, M5S 3H8 Canada (Canada); Addison, Graeme E.; Halpern, Mark [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada (Canada); Battistelli, Elia S. [Department of Physics, University of Rome ' ' La Sapienza' ' , Piazzale Aldo Moro 5, I-00185 Rome (Italy); Crichton, Devin; Gralla, Megan [Dept. of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Devlin, Mark J.; Dicker, Simon [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA, 19104 (United States); Dünner, Rolando [Departamento de Astronomía y Astrofísica, Facultad de Física, Pontificía Universidad Católica, Casilla 306, Santiago 22 (Chile); Fowler, Joseph W. [NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO, 80305 (United States); Hasselfield, Matthew; Hlozek, Renée [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Hilton, Matt, E-mail: sudeepphys@gmail.com [Centre for Astronomy and Particle Theory, School of Physics and Astronomy, University of Nottingham, NG7 2RD (United Kingdom); and others

    2014-04-01

    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 ΛCDM 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 convergence power spectrum at 4.6σ detection significance.

  11. The Atacama Cosmology Telescope: A Measurement of the Primordial Power Spectrum

    Science.gov (United States)

    Hlozek, Renee; Dunkley, Joanna; Addison, Graeme; Appel, John William; Bond, J. Richard; Carvalho, C. Sofia; Das, Sudeep; Devlin, Mark J.; Duenner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W.; Gallardo, Patricio; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D.; Hughes, John P.; Irwin, Kent D.; Klein, Jeff; Kosowsky, Arthur; Marriage, Tobias A.; Marsden, Danica; Menanteau, Felipe; Wollack, Ed

    2011-01-01

    We present constraints on the primordial power spectrum of adiabatic fluctuations using data from the 2008 Southern Survey of the Atacama Cosmology Telescope (ACT). The angular resolution of ACT provides sensitivity to scales beyond l = 1000 for resolution of multiple peaks in the primordial temperature power spectrum, which enables us to probe the primordial power spectrum of adiabatic scalar perturbations with wavenumbers up to k approx. = 0.2 Mp/c. We find no evidence for deviation from power-law fluctuations over two decades in scale. Matter fluctuations inferred from the primordial temperature power spectrum evolve over cosmic time and can be used to predict the matter power spectrum at late times; we illustrate the overlap of the matter power inferred from CMB measurements (which probe the power spectrum in thc linear regime) with existing probes of galaxy clustering, cluster abundances and weak lensing constraints on the primordial power. This highlights the range of scales probed by current measurement.s of the matter power spectrum.

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

    International Nuclear Information System (INIS)

    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 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

  13. Hydrogeology of the lacustrine system of the eastern margin of the Salar the Atacama (Chile)

    International Nuclear Information System (INIS)

    A hydrogeological conceptual model of the Eastern margin of the Salar de Atacama (Chile) is proposed taking into account climatic, geological, geomorphological, piezometric, chemical and isotopic data. The study establishes the processes that explain the hydrochemical evolution of waters from salty groundwater in the alluvial aquifer located in eastern part of basin until brines at the saline aquifer of the Salar. The main processes associated with this hydrochemical evolution are evaporation and mixing, but water-crust interaction in the discharge areas of the alluvial aquifer associated with the saline wedge also modifies groundwater composition, and plays a role in the dynamics of the evaporitic crusts in the Salar. The existence of low permeability materials near the surface explains the existence of the permanent surface water bodies in the study area. Based on the data collected in the study three different mechanisms are proposed regarding the main sources of water to the lagoons: (1) discharge of saline groundwater from the detrital and volcanic aquifers of the E margin, (2) discharge of surface waters associated to the N area (Burro Muerto channel), and (3) a combination of both previous mechanisms. (Author).

  14. Probing Titan's Complex Atmospheric Chemistry Using the Atacama Large Millimeter/Submillimeter Array

    Science.gov (United States)

    Cordiner, Martin A.; Nixon, Conor; Charnley, Steven B.; Teanby, Nick; Irwin, Pat; Serigano, Joseph; Palmer, Maureen; Kisiel, Zbigniew

    2015-01-01

    Titan is Saturn's largest moon, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Atmospheric photochemistry results in the production of a wide range of complex organic molecules, including hydrocarbons, nitriles, aromatics and other species of possible pre-biotic relevance. Titan's carbon-rich atmosphere may be analogous to that of primitive terrestrial planets throughout the universe, yet its origin, evolution and complete chemical inventory are not well understood. Here we present spatially-resolved maps of emission from C2H5CN, HNC, HC3N, CH3CN and CH3CCH in Titan's atmosphere, observed using the Atacama Large Millimeter/submillimeter Array (ALMA) in 2012-2013. These data show previously-undetected spatial structures for the observed species and provide the first spectroscopic detection of C2H5CN on Titan. Our maps show spatially resolved peaks in Titan's northern and southern hemispheres, consistent with photochemical production and transport in the upper atmosphere followed by subsidence over the poles. The HNC emission peaks are offset from the polar axis, indicating that Titan's mesosphere may be more longitudinally variable than previously thought.

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

    International Nuclear Information System (INIS)

    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 TU149= 106.7 ± 2.2 K and TU219= 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 TS149= 137.3 ± 3.2 K and TS219= 137.3 ± 4.7 K

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

    Science.gov (United States)

    Das, Sudeep; Louis, Thibaut; Nolta, Michael R.; Addison, Graeme E.; Battisetti, Elia S.; Bond, J. Richard; Calabrese, Erminia; Crichton, Devin; Devlin, Mark J.; Dicker, Simon; Dunkley, Joanna; Dunner, Rolando; Fowler, Joseph W.; Gralla, Megan; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D.; Hlozek, Renee; Huffenberger, Kevin M.; Hughes, John P.; Irwin, Kent D; Kosowsky, Arthur; Wollack, Ed

    2014-01-01

    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 ?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 convergence power spectrum at 4.6s detection significance.

  17. THE ATACAMA COSMOLOGY TELESCOPE: A MEASUREMENT OF THE PRIMORDIAL POWER SPECTRUM

    International Nuclear Information System (INIS)

    We present constraints on the primordial power spectrum of adiabatic fluctuations using data from the 2008 Southern Survey of the Atacama Cosmology Telescope (ACT) in combination with measurements from the Wilkinson Microwave Anisotropy Probe and a prior on the Hubble constant. The angular resolution of ACT provides sensitivity to scales beyond l = 1000 for resolution of multiple peaks in the primordial temperature power spectrum, which enables us to probe the primordial power spectrum of adiabatic scalar perturbations with wavenumbers up to k ≅ 0.2 Mpc–1. We find no evidence for deviation from power-law fluctuations over two decades in scale. Matter fluctuations inferred from the primordial temperature power spectrum evolve over cosmic time and can be used to predict the matter power spectrum at late times; we illustrate the overlap of the matter power inferred from cosmic microwave background measurements (which probe the power spectrum in the linear regime) with existing probes of galaxy clustering, cluster abundances, and weak-lensing constraints on the primordial power. This highlights the range of scales probed by current measurements of the matter power spectrum.

  18. THE ATACAMA COSMOLOGY TELESCOPE (ACT): BEAM PROFILES AND FIRST SZ CLUSTER MAPS

    International Nuclear Information System (INIS)

    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 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.

  19. The Atacama Cosmology Telescope: Cross-Correlation of Cosmic Microwave Background Lensing and Quasars

    Science.gov (United States)

    Sherwin, Blake D; Das, Sudeep; Haijian, Amir; Addison, Graeme; Bond, Richard; Crichton, Devin; Devlin, Mark J.; Dunkley, Joanna; Gralla, Megan B.; Halpern, Mark; Hill, J. Colin; Hincks, Adam D.; Hughes, John P.; Huffenberger, Kevin; Hlozek, Renee; Kosowsky, Arthur; Louis, Thibaut; Marriage, Tobias A.; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D.; Page, Lyman A.; Reese. Erik D.; Sehgal, Neelima; Sievers, Jon; Sifon, Cristobal; Spergel, David N.; Staggs, Suzanne T.; Switzer, Eric R.; Wollack, Ed.

    2012-01-01

    We measure the cross-correlation of Atacama cosmology telescope cosmic microwave background (CMB) lensing convergence maps with quasar maps made from the Sloan Digital Sky Survey DR8 SDSS-XDQSO photometric catalog. The CMB lensing quasar cross-power spectrum is detected for the first time at a significance of 3.8 sigma, which directly confirms that the quasar distribution traces the mass distribution at high redshifts z > 1. Our detection passes a number of null tests and systematic checks. Using this cross-power spectrum, we measure the amplitude of the linear quasar bias assuming a template for its redshift dependence, and find the amplitude to be consistent with an earlier measurement from clustering; at redshift z ap 1.4, the peak of the distribution of quasars in our maps, our measurement corresponds to a bias of b = 2.5 +/- 0.6. With the signal-to-noise ratio on CMB lensing measurements likely to improve by an order of magnitude over the next few years, our results demonstrate the potential of CMB lensing crosscorrelations to probe astrophysics at high redshifts.

  20. PLANETARY TRANSITS WITH THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY RADIO INTERFEROMETER

    International Nuclear Information System (INIS)

    Planetary transits are commonly observed at visible wavelengths. Here we investigate the shape of a planetary transit observed at radio wavelengths. Solar maps at 17 GHz are used as a proxy for the stellar eclipse by several sizes of planets from super-Earths to hot Jupiters. The relative depth at mid-transit is the same as observed at visible wavelengths, but the limb brightening of the stellar disk at 17 GHz is clearly seen in the shape of the transit light curve. Moreover, when the planet occults an active region the depth of the transit decreases even further, depending on the brightness of the active region relative to the surrounding disk. For intense active region, with 50 times the brightness temperature of the surrounding disk, the decrease can supercede the unperturbed transit depth depending on the size of the eclipsing planet. For a super-Earth (Rp = 0.02 Rs ) crossing, the decrease in intensity is 0.04%, increasing to 0.86% in the case when a strong active region is present. On the other hand, for a hot Jupiter with Rp = 0.17Rs , the unperturbed transit depth is 3% increasing to 4.7% when covering this strong active region. This kind of behavior can be verified with observation of planetary transits with the Atacama Large Millimeter/submillimeter Array radio interferometer

  1. The Atacama Cosmology Telescope: Likelihood for Small-Scale CMB Data

    Science.gov (United States)

    Dunkley, J.; Calabrese, E.; Sievers, J.; Addison, G. E.; Battaglia, N.; Battistelli, E. S.; Bond, J. R.; Das, S.; Devlin, M. J.; Dunner, R.; Fowler, J. W.; Gralla, M.; Hajian, A.; Halpern, M.; Hasselfield, M.; Hincks, A. D.; Hlozek, R.; Hughes, J. P.; Irwin, K. D.; Kosowsky, A.; Louis, T.; Marriage, T. A.; Marsden, D.; Menanteau, F.; Niemack, M.

    2013-01-01

    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 ?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

  2. The Atacama Cosmology Telescope: temperature and gravitational lensing power spectrum measurements from three seasons of data

    International Nuclear Information System (INIS)

    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 ΛCDM 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 convergence power spectrum at 4.6σ detection significance

  3. PLANETARY TRANSITS WITH THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY RADIO INTERFEROMETER

    Energy Technology Data Exchange (ETDEWEB)

    Selhorst, C. L.; Barbosa, C. L. [IP and D, Universidade do Vale do Paraíba (UNIVAP), São José dos Campos, SP (Brazil); Válio, Adriana, E-mail: caius@univap.br [CRAAM, Universidade Presbiteriana Mackenzie, São Paulo, SP (Brazil)

    2013-11-10

    Planetary transits are commonly observed at visible wavelengths. Here we investigate the shape of a planetary transit observed at radio wavelengths. Solar maps at 17 GHz are used as a proxy for the stellar eclipse by several sizes of planets from super-Earths to hot Jupiters. The relative depth at mid-transit is the same as observed at visible wavelengths, but the limb brightening of the stellar disk at 17 GHz is clearly seen in the shape of the transit light curve. Moreover, when the planet occults an active region the depth of the transit decreases even further, depending on the brightness of the active region relative to the surrounding disk. For intense active region, with 50 times the brightness temperature of the surrounding disk, the decrease can supercede the unperturbed transit depth depending on the size of the eclipsing planet. For a super-Earth (R{sub p} = 0.02 R{sub s} ) crossing, the decrease in intensity is 0.04%, increasing to 0.86% in the case when a strong active region is present. On the other hand, for a hot Jupiter with R{sub p} = 0.17R{sub s} , the unperturbed transit depth is 3% increasing to 4.7% when covering this strong active region. This kind of behavior can be verified with observation of planetary transits with the Atacama Large Millimeter/submillimeter Array radio interferometer.

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

    Science.gov (United States)

    Hasselfield, Matthew; Moodley, Kavilan; 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 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(149/U) = 106.7 +/- 2.2 K and T(219/U) = 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(149/S) = 137.3 +/- 3.2 K and T(219/S) = 137.3 +/- 4.7 K.

  5. 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...

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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)

  11. 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.

  12. 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.

  13. 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.

  14. El género Cymatoceras (Nautilida) en el Cretácico Inferior de la Cuenca de Atacama, norte de Chile The genus Cymatoceras (Nautilida) in the Lower Cretaceous of the Atacama Basin, northern Chile

    OpenAIRE

    Marcela Cichowolski; Francisco A. Mourgues; Ernesto Pérez d'A

    2004-01-01

    Se describen restos fragmentarios de nautílidos del género Cymatoceras Hyatt, provenientes de estratos barremianos de la Cuenca de Atacama, norte de Chile. Los especímenes corresponden a dos taxones: Cymatoceras sp. del Barremiano tardío alto, cuya preservación es deficiente, aunque su tipo de ornamentación, con costillas gruesas y un seno ventral muy marcado, es sólo conocida, hasta el momento, en este taxón y Cymatoceras cf. perstriatum (Steuer), del Barremiano tardío. El material chileno e...

  15. MEDIR, AMOJONAR, REPARTIR: TERRITORIALIDADES Y PRÁCTICAS DEMARCATORIAS EN EL CAMINO INCAICO DE ATACAMA (II REGIÓN, CHILE) MEASURING, POSTING, ALLOCATION: TERRITORIALITY AND DEMARCATION PRACTICES ALONG THE ATACAMA INKA ROAD (II REGION, CHILE)

    OpenAIRE

    Cecilia Sanhueza Tohá

    2004-01-01

    A partir del registro arqueológico de los caminos incaicos de la antigua región de Atacama (II Región, Chile), se desarrolla un análisis etnohistórico interpretativo de los denominados hitos, mojones o topus, identificados como un rasgo característico de la vialidad estatal. Desde los antecedentes aportados por la literatura colonial y los vocabularios indígenas, se incursiona en los contenidos semánticos asociados a este tipo de estructuras, estableciendo que estos aparentes señalizadores de...

  16. 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.

  17. 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...

  18. Morphodynamics of Planetary Deserts: A Laboratory Approach

    Science.gov (United States)

    Garcia, A.; Courrech Du Pont, S.; Rodriguez, S.

    2014-12-01

    Earth deserts show a rich variety of dune shapes from transverse to barchan, star and linear dunes depending on the history of wind regimes (strength and variability) and sand availability [1]. In desert, exposed to one wind direction, dunes perpendicular to the wind direction are found to be transverse or barchans, only sand availability plays a key role on their formation and evolution. However, the evolution time scale of such structures (several years) limits our investigation of their morphodynamics understanding. We use here, a laboratory experiment able to considerably reduce space and time scales by reproducing millimeter to centimeter subaqueous dunes by controlling environmental parameters such as type of wind (multi-winds, bimodal, quasi-bimodal or unidirectional wind) and amount of sediment [2,3]. This set up allows us to characterize more precisely the different modes of dune formation and long-term evolution, and to constrain the physics behind the morphogenesis and dynamics of dunes. Indeed, the formation, evolution and transition between the different dune modes are better understood and quantified thanks to a new setting experiment able to give a remote sediment source in continuous (closer to what happens in terrestrial desert): a sand distributor that controls the input sand flow. Firstly, in a one wind direction conditions, we managed to follow and quantify the growth of the instability of transverse dunes that break into barchans when the sand supply is low and reversely when the sand supply is higher, barchan fields evolve to bars dunes ending to form transverse. The next step will be to perform experiments under two winds conditions in order to better constrain the formation mode of linear dunes, depending also only on the input sand flux. Previous experiments shown that linear "finger" dunes can be triggered by the break of transverse dunes and then the elongating of one barchan's arm [4]. These studies can farther explain more precisely in

  19. 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

  20. 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.

  1. 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...

  2. 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…

  3. The Desert and the Sown Project in Northern Jordan

    DEFF Research Database (Denmark)

    Kerner, Susanne

    The desert and sown project, which started in 1999 and continued in 2008-2009, studied the region between the settled areas east of Irbid and Ramtha and the surrounding desert at Mafraq (northern Jordan). Large parts of the material comes from the Palaeolithic period, while some smaller tells dat...

  4. 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.

  5. 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

  6. Surfzone dynamics of the Konkan coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Chandramohan, P.; Anand, N.M.; Nayak, B.U.

    The Konkan Coast has the distinct morphological features than the rest of the Indian Coast. Field studies on beach variation, littoral environmental observation and longshore sediment transport were carried out for a period of one year, between...

  7. 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

  8. Miocene-Quaternary structural evolution of the Uyuni-Atacama region, Andes of Chile and Bolivia

    Science.gov (United States)

    Tibaldi, A.; Corazzato, C.; Rovida, A.

    2009-06-01

    We describe the Miocene-Quaternary geological-structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognized four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E-W direction of shortening in the northern part of the studied area and a WNW-ESE shortening in the southern part. The following two events, of Pliocene age, are characterized by lower shortening amounts; they occurred first by reverse faulting with a NW-SE-trending greatest principal stress ( σ1, computed with striated fault planes) and a vertical least principal stress ( σ3), followed by pervasive strike-slip faulting with the same NW-SE-trending σ1 and a horizontal NE-SW σ3. The fourth event, dating to the late Pliocene-Quaternary is characterized by normal faulting: the σ3 still trends NE-SW, whereas the intermediate principal stress σ2 exchanged with σ1. Volcanism accompanied both the contractional, transcurrent and extensional tectonic phases. The Mio-Pliocene compression appears directly linked to a rapid convergence and an apparently important coupling between the continental and oceanic plates. The E-W to WNW-ESE direction of shortening of the Miocene structures and the NW-SE σ1 of the Pliocene structures seem to be more linked to an intra-Andean re-orientation of structures following the WNW-directed absolute motion of the South-American Plate. The extensional deformations can be interpreted as related to gravity forces affecting the highest parts of the volcanic belt in a sort of asymmetrical (SW-ward) collapse of the belt.

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

    Science.gov (United States)

    Marriage, T. A.; Juin, J. B.; 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.

    2011-01-01

    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 mJy 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 alp[ha (sub 5-20) = -0.07 +/- 0.06, alpha (sub 20-148) -0.39 +/- 0.04, and alpha (sub 5-148) = -0.20 +/- 0.03. When the measured spectral indices are taken into account, the 148 GHz differential source counts are consistent with previous measurements at 30 GHz in the context of a source count model dominated by radio sources. Extrapolating with an appropriately rescaled model for the radio source counts, the Poisson contribution to the spatial power spectrum from synchrotron-dominated sources with flux density less than 20 mJy is C(sup Sync) = (2.8 +/- 0.3) x 1O (exp-6) micro K(exp 2).

  10. The Atacama Cosmology Telescope: Cosmology from Galaxy Clusters Detected via the Sunyaev-Zeldovich Effect

    International Nuclear Information System (INIS)

    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 σ8 = 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 σ8 = 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 σ8 = 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.

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

    International Nuclear Information System (INIS)

    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 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 150.7o ± 0.6o when smoothed with a 5' Gaussian beam

  12. Data characteristics and preliminary results from the atacama b-mode search (ABS)

    Science.gov (United States)

    Visnjic, Catherine

    The Atacama B-Mode Search (ABS) is a 145 GHz polarimeter located at a high altitude site on Cerro Toco, in the Andes of northern Chile. Having deployed in early 2012, it is currently in its second year of operation, observing the polarization of the Cosmic Microwave Background (CMB). It seeks to probe the as yet undetected odd-parity B-modes of the polarization, which would have been created by the primordial gravitational wave background (GWB) predicted by theories of inflation. The magnitude of the B-mode signal is characterized by the tensor-to-scalar ratio, r. ABS features 60 cm cryogenic reflectors in the crossed-Dragone configuration, and a warm, continuously rotating sapphire half-wave plate to modulate the polarization of incoming radiation. The focal plane consists of 480 antenna-coupled transition edge sensor bolometers, arranged in orthogonal pairs for polarization sensitivity, and coupled to feedhorns in a hexagonal array. In this thesis we describe the ABS instrument in the state in which it is now operating, outline the first season of observations, and characterize the data obtained. Focusing on observations of the primary CMB field during a one month reference period, we detail the algorithms currently used to select the data suitable for making maps. This is the first pass at data cuts and provides a conservative estimate for the sensitivity of ABS to the polarization modes in the sky. We project that with one year total observation time of the primary CMB field, ABS should be able to detect the B-mode signal at roughly the level of r = 0.03.

  13. 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.

  14. 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.

  15. 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.

  16. The Atacama Cosmology Telescope: Cosmological Parameters from the 2008 Power Spectrum

    Science.gov (United States)

    Dunkley, J.; Hlozek, R.; 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.; Bertrand Doriese, W.; Dunner, R.; Essinger-Hileman, T.; Fisher, R. P.; Fowler, J. W.; Hajian, A.; Moseley, H.; Wollack, E.

    2011-01-01

    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(exp 2) with the Atacama Cosmology Telescope (ACT) during its 2008 season. ACT measures fluctuations at scales 500 cosmological parameters from the less contaminated 148 GHz spectrum, marginalizing over SZ and source power. The ACDM cosmological model is a good fit to the data (chi square/dof = 29/46), and ACDM parameters estimated from ACT+Wilkinson Microwave Anisotropy Probe (WMAP) are consistent with the seven-year WMAP limits, with scale invariant n(sub s) = 1 excluded at 99.7% confidence level (CL) (3 sigma). A model with no CMB lensing is disfavored at 2.8 sigma. By measuring the third to seventh acoustic peaks, and probing the Silk damping regime, the ACT data improve limits on cosmological parameters that affect the small-scale CMB power. The ACT data combined with WMAP give a 6 sigma detection of primordial helium, with Y(sub p) = 0.313 +/- 0.044, and a 4 sigma detection of relativistic species, assumed to be neutrinos, with N(sub eff) = 5.3 +/- 1.3 (4.6 +/- 0.8 with BAO+H(sub 0) data). From the CMB alone the running of the spectral index is constrained to be d(sub s) / d ln k = -0,034 +/- 0,018, the limit on the tensor-to-scalar ratio is r < 0,25 (95% CL), and the possible contribution of Nambu cosmic strings to the power spectrum is constrained to string tension G(sub mu) < 1.6 x 10(exp -7) (95% CL),

  17. The Atacama Large Millimeter/submillimeter Array: A New Window on the Universe

    Science.gov (United States)

    Beasley, Anthony J.

    2013-06-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) is the largest ground-based global astronomy endeavor in history. Composed of 66 high-precision antennas located on an excellent site at 5000m+ elevation on the Chajnantor plateau in northern Chile, ALMA is delivering the astronomy community orders of magnitude improvements in millimeter-wavelength sensitivity, frequency coverage, resolution, imaging, and spectral capabilities, impacting most fields of astrophysics and opening multiple new scientific frontiers. ALMA’s capabilities span wavelengths from 9.6 to 0.3 mm (31-950 GHz), a key part of the electromagnetic spectrum for observing the first stars and galaxies, directly imaging planetary formation, and studying the energy output from supermassive black holes in starburst galaxies. ALMA’s inauguration on 13 March 2013 marked the Project’s transition to operation as a fully-fledged Observatory. This session will review ALMA’s origins and history, current technical capabilities, and describe its primary scientific goals. Innovative aspects of its design, construction, operation, and governance will be highlighted, including the key roles of the North American ALMA Science Center at the National Radio Astronomy Observatory in Charlottesville, Virginia and the Joint ALMA Observatory in Chile. Development of the state-of-the-art technologies that are enabling the highest impact science will be described. Science operations were initiated 30 September 2011, and research results will be presented from both the Cycle 0 and Cycle 1 Early Science opportunities. This session will conclude with the vision for the Development Program that will maintain ALMA’s capabilities at the forefront of modern astronomy. ALMA is a partnership of North America, Europe, and East Asia in cooperation with the Republic of Chile. ALMA is funded in North America by the U.S. National Science Foundation, in cooperation with the National Research Council of Canada, and the National

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

    International Nuclear Information System (INIS)

    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 ℓ2Cℓ/2π of the thermal SZ power spectrum at 148 GHz is measured to be 3.4±1.4  μK2 at ℓ = 3000, while the corresponding amplitude of the kinematic SZ power spectrum has a 95% confidence level upper limit of 8.6  μK2. 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 Neff = 2.79±0.56, in agreement with the canonical value of Neff = 3.046 for three massless neutrinos. We constrain the sum of the neutrino masses to be Σmν < 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 Yp = 0.225±0.034, and measure no variation in the fine structure constant α since recombination, with α/α0 = 1.004±0.005. We also find no evidence for any running of the scalar spectral index, dns/dln k = −0.004±0.012

  19. THE ATACAMA COSMOLOGY TELESCOPE: COSMOLOGY FROM GALAXY CLUSTERS DETECTED VIA THE SUNYAEV-ZEL'DOVICH EFFECT

    International Nuclear Information System (INIS)

    We present constraints on cosmological parameters based on a sample of Sunyaev-Zel'dovich-selected (SZ-selected) galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of nine optically confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 deg2 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 four-parameter fit. Marginalizing over the values of the parameters in this fit with conservative priors gives σ8 = 0.851 ± 0.115 and w = -1.14 ± 0.35 for a spatially flat wCDM cosmological model with Wilkinson Microwave Anisotropy Probe (WMAP) seven-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP seven-year constraints alone. Fixing the scaling relation between the cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find σ8 = 0.821 ± 0.044 and w = -1.05 ± 0.20. These results are consistent with constraints from WMAP7 plus baryon acoustic oscillations plus Type Ia supernova which give σ8 = 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.

  20. 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.

  1. 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.

  2. THE ATACAMA COSMOLOGY TELESCOPE: EXTRAGALACTIC SOURCES AT 148 GHz IN THE 2008 SURVEY

    International Nuclear Information System (INIS)

    We report on extragalactic sources detected in a 455 deg2 map of the southern sky made with data at a frequency of 148 GHz from the Atacama Cosmology Telescope (ACT) 2008 observing season. We provide a catalog of 157 sources with flux densities spanning two orders of magnitude: from 15 mJy 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 millimeter-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 α5-20 = -0.07 ± 0.06, α20-148 = -0.39 ± 0.04, and α5-148 = -0.20 ± 0.03. When the measured spectral indices are taken into account, the 148 GHz differential source counts are consistent with previous measurements at 30 GHz in the context of a source count model dominated by radio sources. Extrapolating with an appropriately rescaled model for the radio source counts, the Poisson contribution to the spatial power spectrum from synchrotron-dominated sources with flux density less than 20 mJy is C Sync = (2.8 ± 0.3) x 10-6μK2.

  3. 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.

  4. 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...

  5. Evolutionary Hotspots in the Mojave Desert

    Directory of Open Access Journals (Sweden)

    Sharyn B. Marks

    2013-04-01

    Full Text Available Genetic diversity within species provides the raw material for adaptation and evolution. Just as regions of high species diversity are conservation targets, identifying regions containing high genetic diversity and divergence within and among populations may be important to protect future evolutionary potential. When multiple co-distributed species show spatial overlap in high genetic diversity and divergence, these regions can be considered evolutionary hotspots. We mapped spatial population genetic structure for 17 animal species across the Mojave Desert, USA. We analyzed these in concurrence and located 10 regions of high genetic diversity, divergence or both among species. These were mainly concentrated along the western and southern boundaries where ecotones between mountain, grassland and desert habitat are prevalent, and along the Colorado River. We evaluated the extent to which these hotspots overlapped protected lands and utility-scale renewable energy development projects of the Bureau of Land Management. While 30–40% of the total hotspot area was categorized as protected, between 3–7% overlapped with proposed renewable energy project footprints, and up to 17% overlapped with project footprints combined with transmission corridors. Overlap of evolutionary hotspots with renewable energy development mainly occurred in 6 of the 10 identified hotspots. Resulting GIS-based maps can be incorporated into ongoing landscape planning efforts and highlight specific regions where further investigation of impacts to population persistence and genetic connectivity may be warranted.

  6. 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.

  7. NUEVO REGISTRO DE CHINCHILLA CHINCHILLA (RODENTIA, CHINCHILLIDAE) PARA LA REGIÓN DE ATACAMA, CHILE. IMPLICANCIAS PARA SU ESTADO DE CONSERVACIÓN

    OpenAIRE

    Pablo Valladares F.; Martín Espinosa; Mauricio Torres; Eric Diaz; Nicolai Zeller; Jorge de La Riva; Moisés Grimberg; Ángel Spotorno

    2012-01-01

    Reportamos un nuevo registro de Chinchilla chinchilla para la Región de Atacama, Chile. Se basa en ejemplares fotografiados por cámaras de movimiento en el Parque Nacional Nevado Tres Cruces y sus alrededores y por restos óseos y de fecas encontrados en laderas de cerros, ya sea con pendiente abrupta o con rodados, ambas formaciones con cuevas de mediano tamaño. No existen reportes científicos para esta especie en la Región de Atacama en los últimos cincuenta años. Se analiza el estado de con...

  8. Geoglyphs of the Peruvian Coast

    Science.gov (United States)

    Ruggles, Clive L. N.

    "Geoglyphs" in the form of lines, geometric designs, and zoomorphic figures were laid out across wide expanses of arid coastal desert ("pampa") near Nazca, in southern Peru. They represent an extraordinary cultural phenomenon but are also notorious for some of the outlandish theories purporting to explain them. Geoglyphs are also found in adjacent pampas as well as being scattered up and down coastal areas of Peru and northern Chile. The idea that they represented a vast "astronomy book", although continuing to be propagated to tourists, is long discredited. However, astronomical considerations may still help to explain a complex phenomenon that clearly stretched over a considerable geographical area and a significant time period. The broader context suggests that astronomy, and particularly observations of sunrise and sunset, may well have played a significant role in regulating a ritual calendar, but the archaeoastronomical evidence to connect this to geoglyph orientations is weak.

  9. 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

  10. 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.

  11. Climate and soil salinity in the deserts of Central Asia

    Science.gov (United States)

    Pankova, E. I.; Konyushkova, M. V.

    2013-07-01

    A comparative analysis of climatic and soil salinity characteristics of the deserts of Central Asia, including deserts of the Turan Depression, the Gobi Desert, and deserts of the Dzungar and Tarim depressions was performed. The climatic characteristics—the degree of aridity, the degree of continentality, and the amount and regime of precipitation—are different in these deserts. No direct relationships between the areas occupied by the automorphic salt-affected soils and the aridity of the climate are observed in the studied regions. In the automorphic landscapes of Asian deserts, the degree and chemistry of the soil salinization and the distribution of salt-affected soils are controlled by the history of the particular territories rather than by their modern climatic conditions. The presence and properties of the salt-bearing rocks and the eolian migration of salts play the most significant role. The deficit of moisture in the modern climate favors the preservation of salt accumulations in places of their origin. The specific features of the climate, including the regime of precipitation, affect the redistribution of salts in the profiles of automorphic salt-affected soils. An increase in the degree of climatic continentality is accompanied by the decrease in the intensity of weathering and initial accumulation of salts. A different situation is observed in the soils of hydromorphic desert landscapes, in which the degree of salinity of the surface horizons and the area occupied by salt-affected soils are directly influenced by the modern climatic conditions.

  12. 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...

  13. 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.

  14. Issues of affinity: exploring population structure in the Middle and Regional Developments Periods of San Pedro de Atacama, Chile.

    Science.gov (United States)

    Torres-Rouff, Christina; Knudson, Kelly J; Hubbe, Mark

    2013-11-01

    The Middle Period (AD 400-1000) in northern Chile's Atacama oases is characterized by an increase in social complexity and regional interaction, much of which was organized around the power and impact of the Tiwanaku polity. Despite the strong cultural influence of Tiwanaku and numerous other groups evident in interactions with Atacameños, the role of immigration into the oases during this period is unclear. While archaeological and bioarchaeological research in the region has shown no evidence that clearly indicates large groups of foreign immigrants, the contemporary increase in interregional exchange networks connecting the oases to other parts of the Andes suggests residential mobility and the possibility that movement of people both into and out of the oases accompanied these foreign influences. Here, we analyze biodistance through cranial non-metric traits in a skeletal sample from prehistoric San Pedro de Atacama to elucidate the extent of foreign influence in the oases and discuss its implications. We analyzed 715 individuals from the Middle Period (AD 400-1000) and later Regional Developments Period (AD 1000-1450), and found greater phenotypic differences between Middle Period cemeteries than among cemeteries in the subsequent period. We argue that this greater diversity extends beyond the relationship between the oases and the renowned Tiwanaku polity and reflects the role of the oases and its different ayllus as a node and way station for the Middle Period's myriad interregional networks. PMID:24104607

  15. 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.

  16. 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

  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. Browning in Desert Boundaries in Asia in Recent Decades

    Science.gov (United States)

    Jeong, Su-Jong; Ho, Chang-Hoi; Brown, Molly E.; Kug, Jong-Seong; Piao, Shilong

    2011-01-01

    In this study, the changes in desert boundaries in Asia (Gobi, Karakum, Lut, Taklimakan, and Thar deserts) during the growing season (April October) in the years 1982 2008 were investigated by analyzing the normalized difference vegetation index (NDVI), precipitation, and temperature. In the desert boundary regions, the domain mean NDVI values increased by 7.2% per decade in 1982 1998 but decreased by 6.8% per decade thereafter. Accordingly, the bare soil areas (or nonvegetated areas) of the inside of the desert boundaries contracted by 9.8% per decade in the 1990s and expanded by 8.7% per decade in the 2000s. It is noted that the five deserts experience nearly simultaneous NDVI changes although they cover a very diverse area of Asia. In contrast, changes in temperature and precipitation in the deserts show rather diverse results. In desert boundaries located along 40 N (Gobi, Taklimakan, and Karakum), the decadal changes in vegetation greenness were mainly related to regional climate during the entire analysis period. Precipitation increased in the 1990s, providing favorable conditions for vegetation growth (i.e., greening), but precipitation reduced (19 mm per decade) and warming intensified (0.7 C per decade) in the 2000s, causing less moisture to be available for vegetation growth (i.e., browning). In desert boundaries below 40 N (Lut and Thar), although an increase in precipitation (8 mm per decade) led to greening in the 1990s, local changes in precipitation and temperature did not necessarily cause browning in the 2000s. Observed multidecadal changes in vegetation greenness in the present study suggest that under significant global and/or regional warming, changes in moisture availability for vegetation growth in desert boundaries are an important factor when understanding decadal changes in areas vulnerable to desertification over Asia.

  19. Desert detritivory: Nutritional ecology of a dung beetle (Pachysoma glentoni) subsisting on plant litter in arid South African sand dunes

    DEFF Research Database (Denmark)

    Holter, Peter; Scholtz, Clarke H; Stenseng, Lena

    2009-01-01

    Dry conditions limit microbial decomposition of plant litter in deserts, which leaves a primary role to detritivorous macroarthropods. In the sandy arid strip along the west coast of South Africa, such detritivores include the large scarabaeid dung beetle Pachysoma glentoni. Highly unusual among...... dung beetles, this species collects surface litter and drags it into an underground storage and feeding chamber which is abandoned after 6-7 days. Fresh stores for single beetles and for breeding pairs (mean depths: 30 and 39 cm) contained about 1.1 and 2.9 g organic matter, respectively. Using...... shown to have relatively high quality (mean atomic C:N ratio: 35) and the beetles assimilated about 60% of it. Estimated weekly water gain per beetle, supplied entirely by the food, was about 0.6 g. Our results highlight unique nutritional adaptations to survival in deserts without the usual dung beetle...

  20. 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.

  1. The Atacama Cosmology Telescope: Cosmological Parameters from Three Seasons of Data

    Science.gov (United States)

    Seivers, Jonathan L.; Hlozek, Renee A.; Nolta, Michael R.; Acquaviva, Viviana; Addison, Graeme E.; Ade, Peter A. R.; Aguirre, Paula; Amiri, Mandana; Appel, John W.; 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.; Doriese, W. Bertrand; Dunkley, Joanna; Moseley, Harvey; Wollack, Ed

    2013-01-01

    We present constraints on cosmological and astrophysical parameters from highresolution 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)/2pi of the thermal SZ power spectrum at 148 GHz is measured to be 3.4 +/- 1.4 micro-K(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 micro-K(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 sigma(m?) is less than 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 alpha since recombination, with alpha/alpha(sub 0) = 1.004 +/- 0.005. We also find no evidence for any running of the scalar spectral index, derivative(n(sub s))/derivative(ln k) = -0.004 +/- 0.012.

  2. THE ATACAMA COSMOLOGY TELESCOPE: RELATION BETWEEN GALAXY CLUSTER OPTICAL RICHNESS AND SUNYAEV-ZEL'DOVICH EFFECT

    International Nuclear Information System (INIS)

    We present the measured Sunyaev-Zel'dovich (SZ) flux from 474 optically selected MaxBCG clusters that fall within the Atacama Cosmology Telescope (ACT) Equatorial survey region. The ACT Equatorial region used in this analysis covers 510 deg2 and overlaps Stripe 82 of the Sloan Digital Sky Survey. We also present the measured SZ flux stacked on 52 X-ray-selected MCXC clusters that fall within the ACT Equatorial region and an ACT Southern survey region covering 455 deg2. We find that the measured SZ flux from the X-ray-selected clusters is consistent with expectations. However, we find that the measured SZ flux from the optically selected clusters is both significantly lower than expectations and lower than the recovered SZ flux measured by the Planck satellite. Since we find a lower recovered SZ signal than Planck, we investigate the possibility that there is a significant offset between the optically selected brightest cluster galaxies (BCGs) and the SZ centers, to which ACT is more sensitive due to its finer resolution. Such offsets can arise due to either an intrinsic physical separation between the BCG and the center of the gas concentration or from misidentification of the cluster BCG. We find that the entire discrepancy for both ACT and Planck can be explained by assuming that the BCGs are offset from the SZ maxima with a uniform random distribution between 0 and 1.5 Mpc. Such large offsets between gas peaks and BCGs for optically selected cluster samples seem unlikely given that we find the physical separation between BCGs and X-ray peaks for an X-ray-selected subsample of MaxBCG clusters to have a much narrower distribution that peaks within 0.2 Mpc. It is possible that other effects are lowering the ACT and Planck signals by the same amount, with offsets between BCGs and SZ peaks explaining the remaining difference between ACT and Planck measurements. Several effects that can lower the SZ signal equally for both ACT and Planck, but not explain the

  3. THE ATACAMA COSMOLOGY TELESCOPE: COSMOLOGICAL PARAMETERS FROM THE 2008 POWER SPECTRUM

    International Nuclear Information System (INIS)

    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 deg2 with the Atacama Cosmology Telescope (ACT) during its 2008 season. ACT measures fluctuations at scales 500 3000 = 6.8 ± 2.9 μK2, where Bl≡l(l + 1)Cl/2π. The IR Poisson power at 148 GHz is B3000 = 7.8 ± 0.7 μK2 (Cl = 5.5 ± 0.5 nK2), and a clustered IR component is required with B3000 = 4.6 ± 0.9 μK2, assuming an analytic model for its power spectrum shape. At 218 GHz only about 15% of the power, approximately 27 μK2, is CMB anisotropy at l = 3000. The remaining 85% is attributed to IR sources (approximately 50% Poisson and 35% clustered), with spectral index α = 3.69 ± 0.14 for flux scaling as S(ν)∝να. We estimate primary cosmological parameters from the less contaminated 148 GHz spectrum, marginalizing over SZ and source power. The ΛCDM cosmological model is a good fit to the data (χ2/dof = 29/46), and ΛCDM parameters estimated from ACT+Wilkinson Microwave Anisotropy Probe (WMAP) are consistent with the seven-year WMAP limits, with scale invariant ns = 1 excluded at 99.7% confidence level (CL) (3σ). A model with no CMB lensing is disfavored at 2.8σ. By measuring the third to seventh acoustic peaks, and probing the Silk damping regime, the ACT data improve limits on cosmological parameters that affect the small-scale CMB power. The ACT data combined with WMAP give a 6σ detection of primordial helium, with YP = 0.313 ± 0.044, and a 4σ detection of relativistic species, assumed to be neutrinos, with Neff = 5.3 ± 1.3 (4.6 ± 0.8 with BAO+H0 data). From the CMB alone the running of the spectral index is constrained to be dns /dln k = -0.034 ± 0.018, the limit on the tensor-to-scalar ratio is r -7 (95% CL).

  4. The Atacama Cosmology Telescope: Relation Between Galaxy Cluster Optical Richness and Sunyaev-Zel'dovich Effect

    Science.gov (United States)

    Sehgal, Neelima; Addison, Graeme; Battaglia, Nick; Battistelli, Elia S.; Bond, J. Richard; Das, Sudeep; Devlin, Mark J.; Dunkley, Joanna; Duenner, Rolando; Gralla, Megan; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D.; Hlozek, Renee; Hughes, John P.; Kosowsky, Arthur; Lin, Yen-Ting; Louis, Thibaut; Marriage, Tobias A.; Marsden, Danica; Menateau, Felipe; Moodley, Kavilan; Wollack, Ed

    2012-01-01

    We present the measured Sunyaev-Zel'dovich (SZ) flux from 474 optically-selected MaxBCG clusters that fall within the Atacama Cosmology Telescope (ACT) Equatorial survey region. The ACT Equatorial region used in this analysis covers 510 square degrees and overlaps Stripe 82 of the Sloan Digital Sky Survey. We also present the measured SZ flux stacked on 52 X-ray-selected MCXC clusters that fall within the ACT Equatorial region and an ACT Southern survey region covering 455 square degrees. We find that the measured SZ flux from the X-ray-selected clusters is consistent with expectations. However, we find that the measured SZ flux from the optically-selected clusters is both significantly lower than expectations and lower than the recovered SZ flux measured by the Planck satellite. Since we find a lower recovered SZ signal than Planck, we investigate the possibility that there is a significant offset between the optically-selected brightest cluster galaxies (BCGs) and the SZ centers, to which ACT is more sensitive due to its finer resolution. Such offsets can arise due to either an intrinsic physical separation between the BCG and the center of the gas concentration or from misidentification of the cluster BCG. We find that the entire discrepancy for both ACT and Planck can be explained by assuming that the BCGs are offset from the SZ maxima with a uniform random distribution between 0 and 1.5 Mpc. In contrast, the physical separation between BCGs and X-ray peaks for an X-ray-selected subsample of MaxBCG clusters shows a much narrower distribution that peaks within 0.2 Mpc. We conclude that while offsets between BCGs and SZ peaks may be an important component in explaining the discrepancy, it is likely that a combination of factors is responsible for the ACT and Planck measurements. Several effects that can lower the SZ signal equally for both ACT and Planck, but not explain the difference in measured signals, include a larger percentage of false detections in the

  5. 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

  6. 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.

  7. 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

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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,...

  15. 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.

  16. 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...

  17. Highly specialized microbial diversity in hyper-arid polar desert

    OpenAIRE

    Pointing, Stephen B.; Chan, Yuki; Lacap, Donnabella C.; Lau, Maggie C. Y.; Jurgens, Joel A.; Farrell, Roberta L.

    2009-01-01

    The McMurdo Dry Valleys in Antarctica are a cold hyperarid polar desert that present extreme challenges to life. Here, we report a culture-independent survey of multidomain microbial biodiversity in McKelvey Valley, a pristine example of the coldest desert on Earth. We demonstrate that life has adapted to form highly-specialized communities in distinct lithic niches occurring concomitantly within this terrain. Endoliths and chasmoliths in sandstone displayed greatest diversity, whereas soil w...

  18. 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...

  19. 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...

  20. 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.

  1. 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.

  2. 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...

  3. 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...

  4. The Atacama Cosmology Telescope: Cosmological Parameters from the 2008 Power Spectrum

    Science.gov (United States)

    Dunkley, J.; Hlozek, R.; 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.; Bertrand Doriese, W.; Dunner, R.; Essinger-Hileman, T.; Fisher, R. P.; Fowler, J. W.; Hajian, A.; Moseley, H.; Wollack, E.

    2011-01-01

    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(exp 2) with the Atacama Cosmology Telescope (ACT) during its 2008 season. ACT measures fluctuations at scales 500 < l < 10,000. We fit a model for the lensed CMB, Sunyaev-Zel'dovich (SZ), and foreground contribution to the 148 GHz and 218 GHz power spectra, including thermal and kinetic SZ, Poisson power from radio and infrared point sources, and clustered power from infrared point sources. At l = 3000, about half the power at 148 GHz comes from primary CMB after masking bright radio sources. The power from thermal and kinetic SZ is estimated to be Beta(sub 3000) is identical to 6.8 +/- 2.9 mu K (exp 2), where Beta (sub l) is identical to l(l + 1) C(sub l)/2pi. The IR Poisson power at 148 GHz is Bewta(sub 3000) 7.8 +/- 0.7 muK(exp 2) (C(sub l) = 5.5 +/- 0.5 nK(exp 2)), and a clustered IR component is required with Beta (sub 3000) = 4.6 +/- 0.9 muK(exp 2), assuming an analytic model for its power spectrum shape. At 218 GHz only about 15% of the power, approximately 27 mu K(exp 2), is CMB anisotropy at l = 3000. The remaining 85% is attributed to IR sources (approximately 50% Poisson and 35% clustered), with spectral index alpha = 3.69 +/- 0.14 for flux scaling as S(nu) varies as nu(sup alpha). We estimate primary cosmological parameters from the less contaminated 148 GHz spectrum, marginalizing over SZ and source power. The ACDM cosmological model is a good fit to the data (chi square/dof = 29/46), and ACDM parameters estimated from ACT+Wilkinson Microwave Anisotropy Probe (WMAP) are consistent with the seven-year WMAP limits, with scale invariant n(sub s) = 1 excluded at 99.7% confidence level (CL) (3 sigma). A model with no CMB lensing is disfavored at 2.8 sigma. By measuring the third to seventh acoustic peaks, and probing the Silk damping regime, the ACT data improve limits on cosmological

  5. Small protohistoric sites (fishing villages?) on the saurashtra coast, West Coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh

    During the maritime archaeological explorations a few sites of protohistoric in nature have been noticed along the saurashtra coast. the trial excavations of a few sites namely Bet Dwarka and Bhokhira on the western saurashtra coast yielded...

  6. From Fireproof Desert to Flammable Grassland: Buffelgrass Invasion in the Sonoran Desert

    Science.gov (United States)

    Betancourt, J. L.

    2007-12-01

    Only a few decades ago, the Sonoran Desert of northwestern Mexico and southern Arizona was considered mostly fireproof, a case of not enough fine fuel to connect the dominant shrubs and cacti. This has changed with invasions by non-native, winter annual and summer-flower perennial grasses that are rapidly transforming fireproof desert into flammable grassland. Of particular concern is buffelgrass, Pennisetum ciliare, a fire-prone and invasive African perennial grass that has already converted millions of hectares across Sonora since the mid-1960s and has made quick headway in southern and central Arizona beginning in the 1980s. Near Tucson and Phoenix, AZ, buffelgrass invasion is proceeding exponentially, with population expansion (and the costs of mitigation) more than doubling every year. As this conversion progresses, there will be increased fire risks, lost tourist revenue, diminished property values, insurmountable setbacks to conservation efforts, and the threat of large ignition fronts in desert valleys routinely spreading into the mountains. Although somewhat belated, an integrated, multi-jurisdictional effort is being organized to reduce ecological and economic impacts. My presentation will summarize the history and context of buffelgrass introduction and invasion, the disconnect in attitudes and policies across state and international boundaries, ongoing management efforts, the role of science and responsibilities of scientists, accelerated spread with changing climate, and impacts to regional ecosystems and economies. This narrative may serve as a template for other semi-arid lands where buffelgrass and similar grasses have become invasive, including Australia, South America, and many islands in the Pacific Ocean (including Hawaii), Indian Ocean, and Caribbean Sea.

  7. 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.

  8. Origin of sulfate in the Salar de Atacama and the Cordillera de la Sal, initial results of an isotopic study

    OpenAIRE

    Spiro, B.; Chong, G.

    1996-01-01

    Les données isotopiques (O34S et 87Sr/86Sr des eaux des ruisseaux qui entrent dans le salar d'Atacama, ainsi que les eaux du salar lui-même et le gypse associé, montrent que l'origine du sulfate est contrôlée par les émissions volcaniques, sans contributions significatives de sulfate maritime. Les données isotopiques de la Cordillère de la Sal, située au nord-ouest et ayant un âge oligocène, indiquent que les sulfates ont la même origine. (Résumé d'auteur)

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

    Science.gov (United States)

    Arriagada, Cesar; Cobbold, Peter R.; Roperch, Pierrick

    2006-02-01

    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, the basin developed in a foreland setting, during periods of thin-skinned and thick-skinned thrusting. Growth strata provide evidence for coeval sedimentation and thrust motions during mid-Cretaceous, Paleogene, and Neogene times. Pre-Neogene deformation was significant in the basin and in surounding areas of the early central Andes. Models that attempt to explain the current thickness of the central Andes should consider Late Cretaceous and Paleogene shortening, as well as the more obvious Neogene and Quaternary shortening.

  10. Spatial characterization of land surface energy fluxes and uncertainty estimation at the Salar de Atacama, Northern Chile

    Science.gov (United States)

    Kampf, Stephanie K.; Tyler, Scott W.

    2006-02-01

    We use Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) data to estimate spatial energy flux and evaporation distributions at the Salar de Atacama, a playa in Northern Chile. Our approach incorporates ASTER surface kinetic temperature, emissivity, and reflectance data, ground-based meteorological measurements, and empirical parameters. Energy flux distributions are estimated using either spatially constant or spatially distributed values of model parameters, with spatially distributed parameters assigned separately to each land cover category in an image classification. We test the sensitivity of energy budget calculations to state variable and parameter values by conducting Monte Carlo simulations for regions with ground energy budget measurements. Results show that assigning spatially distributed model parameters via land cover classifications yields significant improvements to ground and sensible heat flux predictions. Latent heat fluxes cannot, however, be predicted with sufficient accuracy to allow estimation of area-integrated evaporative moisture loss at this low-evaporation playa.

  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. THE ATACAMA COSMOLOGY TELESCOPE: DETECTION OF SUNYAEV-ZEL'DOVICH DECREMENT IN GROUPS AND CLUSTERS ASSOCIATED WITH LUMINOUS RED GALAXIES

    International Nuclear Information System (INIS)

    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. The LRG sample is divided by luminosity into four bins, and estimates for the central SZ 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 Y200 and clustering properties to relate the galaxy luminosity to halo mass. We also use a relation between brightest cluster galaxy luminosity and cluster mass based on stacked gravitational lensing measurements to estimate the characteristic halo masses. The masses are found to be around 1014 Msun.

  13. 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; Dünner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hincks, Adam D; Hlozek, Renée; Hughes, John P; Irwin, Kent D; Klein, Jeff; Kosowsky, Arthur; Marriage, Tobias A; Marsden, Danica; Moodley, Kavilan; Menanteau, Felipe; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Reese, Erik D; Schmitt, Benjamin L; Sehgal, Neelima; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Visnjic, Katerina; Wollack, Ed

    2011-07-01

    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 Ω(Λ) confirms other measurements from supernovae, galaxy clusters, and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool. PMID:21797591

  14. 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...

  15. 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.

  16. 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.

  17. Solar saves Coast Guard millions

    International Nuclear Information System (INIS)

    The Canadian Coast Guard began converting its navigational aids, including 5,500 buoys, lights, and fog signals to solar power in the early 1980s. The conversion has saved them tens of millions of dollars in operation and maintenance costs. The photovoltaic (PV) systems which are used to power the navigational aids range from 10 to 2,400 watts. In addition to environmental benefits, the other advantages over primary batteries and diesel generators which previously provided power to the aids, are that the PV system provides a uniform voltage supply throughout the year and servicing does not have to be compressed into the peak period at the beginning of each shipping season. The payback for the small PV systems is less than three years. The PV systems have proven to be very reliable even in rough seas with ice build up and humidity. 1 fig

  18. Solar saves Coast Guard millions

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1998-06-01

    The Canadian Coast Guard began converting its navigational aids, including 5,500 buoys, lights, and fog signals to solar power in the early 1980s. The conversion has saved them tens of millions of dollars in operation and maintenance costs. The photovoltaic (PV) systems which are used to power the navigational aids range from 10 to 2,400 watts. In addition to environmental benefits, the other advantages over primary batteries and diesel generators which previously provided power to the aids, are that the PV system provides a uniform voltage supply throughout the year and servicing does not have to be compressed into the peak period at the beginning of each shipping season. The payback for the small PV systems is less than three years. The PV systems have proven to be very reliable even in rough seas with ice build up and humidity. 1 fig.

  19. Characterization of land surface energy fluxes at the Salar de Atacama, Northern Chile using ASTER image classification

    Science.gov (United States)

    Kampf, S. K.; Tyler, S. W.

    2003-12-01

    Models of land surface energy fluxes often use remotely sensed data to derive surface temperature, albedo, and emissivity, important parameters in energy budget calculations. The ability to determine the spatial distribution of these parameters can lead to improved estimations of the spatial variability of land surface energy fluxes. However, other parameters used in energy flux calculations such as aerodynamic resistance are not directly linked to quantities commonly derived from remotely sensed data. If images can be accurately classified into separate land cover types, empirically determined values of unknown parameters can then be assigned separately to each land cover classification. This study examines several techniques of determining the spatial distribution of land surface energy fluxes at the Salar de Atacama, a large playa in northern Chile. Fluxes are calculated using Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) Level 2 surface kinetic temperature, surface emissivity, and surface reflectance data in conjunction with ground-based meteorological measurements. Energy fluxes are calculated initially by applying a single value of aerodynamic resistance to the entire image area. Subsequently, the ASTER scene is classified into distinct land cover types, and land surface roughness is characterized using the ratio of ASTER band 3N (nadir-viewing) to band 3B (back-viewing). Separate values of aerodynamic resistance are then assigned to each land cover type, and energy fluxes over the entire Salar de Atacama are calculated using these spatially distributed aerodynamic resistance values. Results of both energy flux calculation techniques are evaluated at several sites on the playa using ground-based energy flux measurements.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. COAST code conversion from Cyber to HP

    International Nuclear Information System (INIS)

    The transient thermal hydraulic behavior of reactor coolant system in a nuclear power plant following loss of coolant flow is analyzed by use of COAST digital computer code. COAST calculates individual loop flow rates and steam generator pressure drops is a function of time following coast-down of any number of reactor coolant pumps. This report firstly describes detailed work carried out for installation of COAST on HP 9000/700 series and code validation results after installation. Secondly, a series of work is also describes in relation to installation of COAST on Apollo DN10000 series as well as relevant code validation results. Attached is a report on software verification and validation results. 7 refs. (Author) .new

  7. Tree planting in deserts and utilization of atomic energy

    International Nuclear Information System (INIS)

    Global environment problems are discussed actively, concretely, those are the warming of the earth, the advance of desertification, the damage due to acid rain, the decrease of tropical forests, the pollution of sea, the depletion of ozone layer and so on. Most of these phenomena advance gradually. However, the advance of desertification is different from other phenomena in that the people in the areas concerned are deprived of their living space and even their lives are threatened at this moment. Desertification is advancing on global scale, and its rate is estimated to be 60,000 km2 yearly. Especially the area where the advance is remarkable is the southern edge of Sahara Desert, which advances southward at 10-30 km in one year. Recently also in Japan, the interest in the prevention of desertification has become high, and the experiment on tree planting in a desert using a huge desert dome of the Institute of Physical and Chemical Research, 'Desert Aquanet concept' of Shimizu Construction Co., Ltd., 'Sahara green belt project' of the Ministry of International Trade and Industry and so on were published. Water and energy for tree planting in deserts, utilization of atomic energy for seawater desalination and the technical fields to which Japan can contribute are reported. (K.I.)

  8. 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.

  9. 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.

  10. 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

  11. Using Near Real-Time Mission Data for Education and Public Outreach: Strategies from the Life in the Atacama E/PO Effort

    Science.gov (United States)

    Myers, E.; Coppin, P.; Wagner, M.; Fischer, K.; Lu, L.; McCloskey, R.; Seneker, D.; Cabrol, N.; Wettergreen, D.; Waggoner, A.

    2005-01-01

    The EventScope educational telepresence project has been involved with education and public outreach for a number of NASA-sponsored missions including the Mars Exploration Rovers, the Odyssey Mission, and the Life in the Atacama project. However, during the second year of operations in the Atacama, a modified version of the EventScope public interface was used as the remote science operations interface. In addition, the EventScope lab hosted remote science operations. This intimate connection with the mission operations allowed the EventScope team to bring the experience of the mission to the public in near real-time. Playing to this strength, the lab developed strategies for releasing E/PO content as close to real-time as possible.

  12. 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.

  13. 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.

  14. Concentration of plutonium in desert plants from contaminated area

    International Nuclear Information System (INIS)

    The investigation of plutonium in desert plants from contaminated sites contributes to the evaluation of its pollution situation and to the survey of plutonium hyper accumulator. The concentration of 239Pu in desert plants collected from a contaminated site was determined, and the influence factors were studied. The concentration of 239Pu in plants was (1.8±4.9) Bq/kg in dry weight, and it means that the plants were contaminated, moreover, the resuspension results in dramatic plutonium pollution of plant surface. The concentration of plutonium in plants depends on species, live stages and the content of plutonium in the rhizosphere soil. The concentration of plutonium in herbage is higher than that in woody plant, and for the seven species of desert plants investigated, it decreases in the order of Hexinia polydichotoma, Phragmites australis, Halostashys caspica, Halogeton arachnoideus, Lycium ruthenicum, Tamarix hispida and Calligonum aphyllum. (authors)

  15. La desregulación de las cooperativas eléctricas no concesionarias en chile: san pedro de atacama como paradigma de referencia

    OpenAIRE

    Ascencio Otárola, Marco Felipe

    2016-01-01

    Este trabajo afrontará el contexto general del sistema eléctrico y su incidencia en casos excepcionales, particularmente con empresas no concesionaras de distribución, poniendo énfasis en un caso referencial de carácter rural, la Cooperativa Eléctrica de San Pedro de Atacama y su desenvolvimiento normativo y fáctico frente a la desregulación

  16. 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.

  17. Energy, water balances, and fluxes in the soil-plant-atmosphere continuum: Dryland and desert cases

    Science.gov (United States)

    Desert environments offer daunting challenges for sustainable agriculture, low precipitation and temperature extremes among them. Yet, desert environments are not all alike, and some deserts are, with the exception of low precipitation, less challenging than some semi-arid regions that routinely sup...

  18. 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 ...

  19. 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.

  20. 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.