These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Recent, slow normal and strike-slip faulting in the Pasto Ventura region of the southern Puna Plateau, NW Argentina  

USGS Publications Warehouse

Recent normal and strike-slip faulting on the Puna Plateau of NW Argentina has been linked to lithospheric foundering, gravitational spreading, plate boundary forces and a decrease in crustal shortening from north to south. However, the timing, kinematics and rate of extension remain poorly constrained. We focus on the Pasto Ventura region (NW Argentina) located on the southern Puna Plateau and recent deformation (<1 Ma). Field mapping and kinematic analysis across offset volcanic cinder cones show that the overall extension direction is subhorizontal, is oriented NE-SW to NNE-SSW, and occurs at a slow, time-integrated rate of 0.02 to 0.08 mm/yr since at least 0.8–0.5 Ma. A regional compilation from this study and existing data shows that recent extension across the Puna Plateau is subhorizontal but varies in azimuthal orientation dramatically. Data from the Pasto Ventura region are consistent with a number of models to explain normal and strike-slip faulting on the Puna Plateau, all of which likely influence the region. Some role for lower lithospheric foundering through dripping appears to be seen based on the regional extension directions and ages of mafic volcanism in the southern Puna Plateau.

Zhou, Renjie; Schoenbohm, Lindsay M.; Cosca, Michael

2013-01-01

2

PASTOS Y PAISAJES LAWNS & LANDSCAPES  

E-print Network

3 IN THIS ISSUE Words from the Editor 1 Maintenance of Container Plantings 1 White Grubs 7 Selecting Próximas 12 Words from the Editor It has been an interesting summer with some common and some not so common sicomoro. El verano no ha sido más seco y los signos del daño por agua son evidente en algunas áreas, y qué

Goodman, Robert M.

3

Reproducción y alimentación del tiburón enano Mustelus dorsalis (Pisces: Triakidae) en el Golfo de Nicoya, Costa Rica: Elementos para un manejo sostenible  

Microsoft Academic Search

Reproduction and feeding habits of Mustelus dorsalis (Pisces: Triakidae) in the Gulf of Nicoya, Costa Rica: Elements for a sustainable management. A total of 311 sharptooth smooth-hound Mustelus dor? salis were collected in the Gulf of Nicoya, Costa Rica from March 1999 to May 2000 to determine reproduction and feeding habits. The fishes were collected using hook and line. 250

José Rodrigo

4

Evaluación de la calidad bromatológica del ensilaje de pasto kikuyo y maní forrajero  

Microsoft Academic Search

Introduction. Ensilage is a method in which the grow of organic micro organisms that degrade organic matter is inhibited, herlping to keep forage. Materials and methods. This work evaluated the effect of four doses of kikuyo grass and forage peanut, suplemented with different concentrations of molasses, related to the nutricional quality of the ensilage produced. A random experimental design was

Adelaida María; Garcés Molina; Ernesto Suárez Holguín; Santiago Ruíz Alzate

5

The aim of the collaborative research group "ENano Nanoanalysis for Energy Technologies" to be established at TU Dresden in the framework of the European Social Fund (ESF) in the Federal State  

E-print Network

. For this group, TU Dresden offers the positions of 8 members of academic staff / junior researchers Given scale E 13 TV-L for all members of the group including Ph.D. candidates and will be on a fulltime weekly to disabled people. Applicants should send a letter of motivation, Curriculum Vitæ, a complete list

6

Conservation Biology, Pages 16381646 Volume 16, No. 6, December 2002  

E-print Network

within low grassland landscapes. Grasshopper Sparrows (Ammodramus savannarum) and Dick- cissels (Spiza pastos al- tos que en parches extensos en paisajes con pastos bajos. Ammodramus savannarum, Spiza

7

Los Elefantes Rosas en las Cupulas en la Legislatura: An Empirical Analysis of the Texas Education Finance Mechanism with Special Emphasis on Bilingual Education  

ERIC Educational Resources Information Center

The State of Texas' education finance mechanism--known as the Foundation School Program (FSP)--was challenged in a series of litigation known as "Edgewood v. Kirby I-IV" and "West Orange Cove I-II". Though the state Supreme Court's holding ultimately moved the Texas Assembly to make changes in the funding mechanism, not since the 1980s has there…

Rolle, Anthony; Torres, Mario; Eason, Noelle

2010-01-01

8

DESEMPENHO DE OVINOS ALIMENTADOS COM DIE TAS À BASE DE SILAGEM DE CAPIM ELEFANTE (PENNISETUM PURPUREUM, SCHUM) CONTENDO OU NÃO BAGAÇO DE CAJU (ANACARDIUM OCCIDENTALE, L.)1  

Microsoft Academic Search

The present work was developed with the objective of evaluating the performance of sheep fed with the silage of elephant grass, with and without dehydrated cashew bagasse, suplemmented with two levels of concentrate ration (1,5 and 2,5% of the live weight - LW). The highest intake of dry matter (DM) was observed in the animals fed with a ration concentrated

MARCÍLIO COSTA TEIXEIRA; JOSÉ NEUMAN; MIRANDA NEIVA; SALETE ALVES DE MORAES; ANA CLARA; RODRIGUES CAVALCANTE; NONATO BRAGA; JOSÉ OSVALDO BESERRA

9

Potencial forrajero del pasto salado Distichlis spicata L. (Greene) en ecosistemas costeros de Baja California Sur, México por el método de \\  

Microsoft Academic Search

Forage potential of the non-domesticated saltgrass Distichlis spicata (Gramineae) was determined by analyzing its chemical and productive variables using principal components analysis (PCA). Plants were collected from five sites amongst three locations, in areas including wetlands shores, centers, and beach. The results suggested that D. spicata is a rough, poorly digested forage, as explained by the statistical significance of the

Arturo Escobar-Hernándezab; Enrique Troyo-Dieguez; José Luis García-Hernández; Hugo Hernández-Contreras; Bernardo Murillo-Amador; Raúl López-Aguilar

10

Use of digital multispectral videography to assess seagrass distribution in San Quintín Bay, Baja California, Mexico Uso de videografía multiespectral digital para evaluar la distribución del pasto marino en Bahía San Quintín, Baja California, México  

Microsoft Academic Search

Apparent threats to the spatial distribution of seagrass in San Quintín Bay prompted us to make a detailed assessment of habitats in the bay. Six coastal habitats and three seagrass subclasses were delineated using airborne digital multispectral videography (DMSV). Eelgrass, Zostera marina, was the predominant seagrass and covered 40% (1949 ha) of the areal extent of the bay in 1999.

David H. Ward; T. Lee Tibbitts; Alexandra Morton; Eduardo Carrera-González; Richard Kempka; Garza García

2004-01-01

11

Caracterización bioquímica del pasto marino Zostera marina en el límite sur de su distribución en el Pacífico Norte Biochemical characterization of the eelgrass Zostera marina at its southern distribution limit in the North Pacific  

Microsoft Academic Search

The eelgrass Zostera marina L. is distributed along the Baja California Peninsula (Mexico) where it is exposed to a wide range of irradiances and temperatures that could promote changes in its biochemical composition. Consequently, the objective of this study was to characterize the variations in the levels of chlorophyll, carbohydrates, proteins, fiber, ash and calories in the shoots of Z.

Alejandro Cabello-Pasini; Raquel Muñiz-Salazar; David H. Ward

12

Biochemical characterization of the eelgrass Zostera marina at its southern distribution limit in the North Pacific [Caracterizacio??n bioqui??mica del pasto marino Zostera marina en el li??mite sur de su distribucio??n en el Paci??fico Norte  

USGS Publications Warehouse

The eelgrass Zostera marina L. is distributed along the Baja California Peninsula (Mexico) where it is exposed to a wide range of irradiances and temperatures that could promote changes in its biochemical composition. Consequently, the objective of this study was to characterize the variations in the levels of chlorophyll, carbohydrates, proteins, fiber, ash and calories in the shoots of Z. marina from the north (San Quintin) and south (Ojo de Liebre and San Ignacio lagoons) of the peninsula. Temperature in the southern lagoons was 5-6??C higher than in the northern lagoon; likewise, in situ irradiance was two-fold greater in the south than in the north. As a result of the lower irradiance levels, the concentration of chlorophyll in the shoots of Z. marina was twice as high (1.7 mg gWW-1) in the northern lagoon than in the southern ones (0.8 mg gWW-1). Similar to chlorophyll levels, the concentration of soluble carbohydrates in the shoots was greater in the northern lagoon than in the southern ones, suggesting that the high levels of chlorophyll are enough to compensate for the low irradiance levels and to maintain a positive carbon balance at San Quintin. On the other hand, the levels of proteins in the shoots from the north of the peninsula were slightly lower than those from the southern populations. In general, these results suggest that the different environmental conditions to which Z. marina is exposed along the peninsula impact its biochemical composition.

Cabello-Pasini, A.; Muniz-Salazar, R.; Ward, D.H.

2004-01-01

13

Use of digital multispectral videography to assess seagrass distribution in San Quinti??n Bay, Baja California, Mexico [Uso de videografi??a multiespectral digital para evaluar la distributio??n del pasto marino en Bahi??a San Quinti??n, Baja California, Me??xico  

USGS Publications Warehouse

Apparent threats to the spatial distribution of seagrass in San Quinti??n Bay prompted us to make a detailed assessment of habitats in the bay. Six coastal habitats and three seagrass subclasses were delineated using airborne digital multispectral videography (DMSV), Eelgrass, Zostera marina, was the predominant seagrass and covered 40% (1949 ha) of the areal extent of the bay in 1999. Eelgrass grew over a wide range of tidal depths from about -3.0 in mean lower low water (MLLW) to about 1.0 m MLLW, but greatest spatial extent occurred in intertidal areas -0.6 m to 1.0 m MLLW. Exposed-continuous (i.e., high density) eelgrass was the most abundant habitat in the bay. Widgeongrass, Ruppia maritima, was the only other seagrass present and covered 3% (136 ha) of the areal extent of the entire bay. Widgeongrass grew in single species stands in the upper intertidal (??? 0.4 MLLW) and intermixed with eelgrass at lower tidal depths. Overall accuracy of the six habitat classes and three subclasses in the DMSV map was relatively high at 84%. Our detailed map of San Quintin Bay can be used in future change detection analyses to monitor the health of seagrasses in the bay.

Ward, D.H.; Tibbitts, T.L.; Morton, A.; Carrera-Gonzalez, E.; Kempka, R.

2004-01-01

14

Serologic Evidence that Ascaris and Toxoplasma Infections Impact Inflammatory Responses to Helicobacter pylori in Colombians  

E-print Network

Background: Helicobacter pylori-infected children from coastal Tumaco, Colombia, have more parasitism, and adults have lower gastric cancer risk compared with high-altitude Pasto/Tuquerres residents. Because helminth and ...

Ek, Courtney

15

Prescribed Range Burning in Texas (Spanish)  

E-print Network

truenan y se parten. En general el combustible de los pastos es relativamente seguro de quemar, mientras que las plantas con altos contenidos de aceite son explosi- vas y pueden causar problemas serios. El contenido de humedad del zacate muerto, hojas y..., cuando el pasto no es flamable (figura 6). Use la misma pr?ctica para cualquier mogote de matorral o material muerto concentra- do en montones. El fuego caliente en los mogotes destruye la vegetaci?n existente, en especial si se quema en la temporada de...

White, Larry D.; Hanselka, C. Wayne

2001-06-18

16

The Condor 112(2):274282 The Cooper Ornithological Society 2010  

E-print Network

, mientras que la abundancia de especies no nativas aumentó con la cobertura de caminos y estructuras. Las alta y negativamente con la cobertura de caminos y estructuras. Elanus leucurus se correlacionó positivamente con los pastos y los árboles, y negativa- mente con la cobertura de caminos y estructuras. Estas

Johnson, Matthew

17

J. Field Ornithol. 82(2):140149, 2011 DOI: 10.1111/j.1557-9263.2011.00316.x Nest-site selection and productivity of Vesper Sparrows  

E-print Network

selection and productivity of ground-nesting Vesper Sparrows (Pooecetes gramineus) across sites productividad en Pooecetes gramineus anidando en h´abitats de pastoreo El pastoreo de ganado en pastos de estepa lugares de anidaci´on y productividad de Pooecetes gramineus que anida en el suelo a trav´es de lugares

18

RESEARCH NOTE/NOTA INVESTIGATIVA DISTRIBUTION, HOST STATUS AND POTENTIAL SOURCES OF  

E-print Network

County, TN, on Eleusine indica (goosegrass). Comparison of the 1978 specimens deposited in the USDA and that there is a potential role of the cytoplasm in conferring resistance. Keywords: goosegrass, Eleusine indica, Zea mays el pasto Eleusine indica. La comparación de los especímenes de 1978 depositados en la Colección de

Flint-Garcia, Sherry

19

In vitro digestibility, physicochemical, thermal and rheological properties of banana starches.  

PubMed

Banana starches (BS) were isolated from Enano, Morado, Valery and Macho cultivars. The BS possessed B-type crystallinity and an amylose content varying from 19.32 to 26.35%. Granules had an oval morphology with different major-to-minor axis ratios, exhibiting both mono- and bi-modal distributions and mean particle sizes varying from 32.5 to 45 ?m. BS displayed zeta-potential values ranging between -32.25 and -17.32 mV, and formed gels of incipient to moderate stability. The enthalpy of gelatinization of BS affected the crystalline order stability within the granules. In-vitro digestibility tests showed fractions as high as 68% of resistant starch. Rheological oscillatory tests at 1 Hz showed that BS dispersions (7.0%, w/w) exhibited Type III behaviour, attributed to the formation of a continuous phase complex three-dimensional amylose gel reinforced by swollen starch granules acting as fillers. Amylose content and granules morphology were the main factors influencing the BS properties. PMID:24299760

Utrilla-Coello, R G; Rodríguez-Huezo, M E; Carrillo-Navas, H; Hernández-Jaimes, C; Vernon-Carter, E J; Alvarez-Ramirez, J

2014-01-30

20

Evidence for wheat-rye nucleolar competition (amphiplasty) in triticale by silver-staining procedure.  

PubMed

Amphiplasty in hexaploid triticale, the artificial amphiploid of tetraploid wheat and diploid rye, is analyzed for the first time using a modified, highly reproducible, silver-staining procedure. A comparative analysis of metaphase somatic cells by phase contrast, C-banding and silver-staining of the hexaploid triticale cv. 'Cachirulo' and its parents, namely, the tetraploid durum wheat cv. 'Enano de Andujar' and the diploid rye cv. 'Petkus' has been made. Two silver-stained nucleolar organizer regions (Ag-NORs) (the chromosome pair 1 R) are observed in all rye plants analyzed, whereas four Ag-NORs (chromosome pairs 1 B and 6 B) are found both in the tetraploid wheat parent and in the triticale. The rye Ag-NORs are absent in the triticale. Since the Agstaining reaction of NORs can be considered as an indication for genetic activity, the silver procedure can be used to visualize gene functionality at the rDNA sites with conventional light microscopy and, consequently, the modified Ag-staining method described can be very useful in analyzing the amphiplasty phenomenon in natural or artificial hybrid combinations and derivatives in the Triticum group and its relatives. PMID:24258550

Lacadena, J R; Cermeño, M C; Orellana, J; Santos, J L

1984-01-01

21

Invertebrates in salt lakes of the Bolivian Altiplano  

Microsoft Academic Search

Based upon a short reconnaissance (March 1991), the chemicalnature and principal invertebrate fauna of seven saline lakes on the Altiplano of southern Bolivia are discussed (Lago de Uru-uru, Pastos Grandes, Lago Ramiditas, Lago Hedionda, Lago Cañapa, Laguna Colorado, pool at L. Colorado). Salinities ranged between 4.4 and 156 g L?1. The fauna was depauperate. Except at the lowest salinities (?1),

W. D. Williams; T. R. Carrick; I. A. E. Bayly; J. Green; D. B. Herbst

1995-01-01

22

Identification of the Calderas for Major Ignimbrites of the Altiplano-Puna Volcanic Complex, Central Andes, Including Two New Super-eruptions  

NASA Astrophysics Data System (ADS)

The Neogene ignimbrite flare-up in the Altiplano-Puna Volcanic Complex (APVC) in the central Andes produced calderas and ignimbrites covering >70,000 km2 in Chile, Bolivia, and Argentina and totaling >11,000 km3 of magma. One of the questions related to this extraordinary occurrence is how long it took for these ignimbrites to be emplaced. In an effort to determine this, we have combined field correlations, high-precision 40Ar/39Ar dating, anisotropy of magnetic susceptibility (AMS) and characteristic remanent magnetism (ChRM) to constrain the dates of the eruptions. Herein we present the paleomagnetic data and preliminary interpretations, including the definition of two new super-eruptions in the APVC (including the youngest yet identified in the APVC). Several ignimbrites occupy similar stratigraphic positions. The Pastos Grandes and Tara Ignimbrites erupted 2.8-3.5 Ma, while the Chuhuilla, Alota, and Guacha Ignimbrites date between 5.3 and 5.6 Ma. The Pastos Grandes and Tara Ignimbrites have similar ChRM directions. The ChRM directions of the Alota and Guacha Ignimbrites are clearly distinct but the Chuhuilla Ignimbrite data have very large dispersion. The thermal demagnetization reveals a single component in nearly all the samples, which may indicate that the ignimbrites were emplaced above the magnetite Curie temperature. Current efforts center on refining and reducing the errors on the ChRM directions. AMS was used to determine flow directions and thus define the source areas for ignimbrites. The 3.51 Ma Tara Ignimbrite, first recognized as ponded ignimbrite in La Pacana caldera and thought to be erupted from there, is sourced in the Guacha caldera of Bolivia, likely from the western dome complex, which yields similar dates. Great thicknesses of Tara Ignimbrite are ponded within the Guacha caldera, and also around Cerro Zapaleri. This is the youngest super-eruption in the central APVC. The Pastos Grandes caldera was previously thought to have formed during the Chuhuilla Ignimbrite eruption at 5.45 Ma. Our AMS data show the Pastos Grandes Ignimbrite was erupted from the Pastos Grandes caldera and new dates show it was emplaced at 2.89 Ma, corroborated by the ChRM data. It is exposed over 6000 km2 with a volume of >800 km3, making it the youngest super-eruption in the APVC. This may have been the reactivation of the caldera after a ~2.5 million year hiatus in ignimbrite-forming eruptions. Our AMS data confirm that the Guacha, Laguna Colorado, and Vilama ignimbrites come from their eponymous calderas, with some topographic effects upon the flow directions.

Ort, M. H.; de Silva, S. L.; Jiménez, N.

2008-12-01

23

Why Range Forage Quality Changes (Spanish)  

E-print Network

/invierno Perenne 4-32 14-74 carga en el corto plazo en un pastizal previamente pastoreado de manera ligera o moderada, puede resultar en una menor calidad de forraje, debido a que los animales son forzados a consumir forra- je viejo o muerto. Si el potrero tiene... antecedentes de pastoreo o uso intenso, la calidad del forraje de los pastos ser? en general m?s alta, debido a que las plantas est?n menos maduras y hay menos material muerto. Estas diferencias en calidad de forraje no sig- nifican que el uso intensivo...

Lyons, Robert K.; Machen, Richard V.; Forbes, T. D. A.

2001-09-10

24

Combined ESR/U-series chronology of Acheulian hominid-bearing layers at Trinchera Galería site, Atapuerca, Spain  

USGS Publications Warehouse

The Sierra de Atapuerca, northern Spain, is known from many prehistoric and palaeontological sites documenting human prehistory in Europe. Three major sites, Gran Dolina, Galería and Sima del Elefante, range in age from the oldest hominin of Western Europe dated to 1.1 to 1.3 Ma (millions of years ago) at Sima del Elefante to c.a. 0.2 Ma on the top of the Galería archaeological sequence. Recently, a chronology based on luminescence methods (Thermoluminescence [TL] and Infrared Stimulated Luminescence [IRSL]) applied to cave sediments was published for the Gran Dolina and Galería sites. The authors proposed for Galería an age of 450 ka (thousands of years ago) for the units lower GIII and GII, suggesting that the human occupation there is younger than the hominid remains of Sima de los Huesos (>530 ka) around 1 km away. In this paper, we present new results obtained by combined Electron Spin Resonance/Uranium-series (ESR/U-series) dating on 20 herbivorous teeth from different levels at the Galería site. They are in agreement with the TL results for the upper part of the stratigraphic sequence (GIV and GIIIb), in the range of between 200 and 250 ka. But for the GIIIa to GIIb levels, the TL ages become abruptly older by 200 ka while ESR ages remain relatively constant. Finally, the TL and ESR data agree in the lowest part of the section (GIIa); both fall in the range of around 350–450 ka. Our results suggest a different interpretation for the GII, GIII and GIV units of Galería and the upper part of Gran Dolina (TD10 and TD11) than obtained by TL. The ESR/U-series results are supported by a Bayesian analysis, which allows a better integration between stratigraphic information and radiometric data.

Falguères, Christophe; Bahain, Jean-Jacques; Bischoff, James L.; Pérez-González, Alfredo; Ortega, Ana Isabel; Ollé, Andreu; Quilles, Anita; Ghaleb, Bassam; Moreno, Davinia; Dolo, Jean-Michel; Shao, Qingfeng; Vallverdú, Josep; Carbonell, Eudald; María Bermúdez de Castro, Jose; Arsuaga, Juan Luis

2013-01-01

25

Quaternary tectonic movements in the Argentine Puna, 24/sup 0/ to 27/sup 0/ s latitude  

SciTech Connect

The Puna of NW Argentina, one of the highest plateaus in the world, is the southern continuation of the Andean Altiplano geomorphic province of Peru and Bolivia. The region is not seismically active and reports of neotectonic movements are scarce. However, the areas of Salar de los Pastos Grandes, Salar del Hombre Muerto and Sierra Calalaste clearly have experienced Quaternary tectonic movements. At Salar de los Pastos Grandes, early Pleistocene lake sediments are offset by reverse faulting. At Salar del Hombre Muerto, Quaternary pyroclastic and debris-flow deposits are unconformable over sediments 5.86 m.y. old that were folded during the Pliocene-Pleistocene Diaguita deformation. Within the Quaternary sediments two separate deformational phases with reverse faulting and shallow thrusting are recognized. The timing of movement is well defined since the deformed strata are covered by a basalt flow 0.75 m.y. old. The flow in turn is affected by normal faulting. Similar normal faults associated with basalt flows were found at Sierra Calalaste. These observations are in accord with pronounced extensional movements and basaltic volcanism at the Calama-Olacapato-Toro Lineament (0.2 m.y. old flows) and might document the Quaternary transition from a compressive to an extensional tectonic regime in the southern Puna.

Strecker, M.R.; Alonso, R.; Rivelli, F.; Mon, R.

1985-01-01

26

Eocene exhumation and basin development in the Puna of northwestern Argentina  

NASA Astrophysics Data System (ADS)

The Puna is part of the larger Puna-Altiplano Plateau (also known as the Central Andean Plateau), characterized by high elevation, low relief, and aridity, located in the central Andes of Bolivia and Argentina. Tertiary sedimentary rocks preserved within the Puna contain a unique archive of information regarding the paleogeography, depositional environments, and timing of sediment source exhumation during the early stages of Andean mountain building. The Eocene Geste Formation in the Salar de Pastos Grandes area (within the central Puna of northwestern Argentina) consists of deposits that are the result of confined to unconfined flows in a sandy to gravelly, braided fluvial system and alluvial fans proximal to the source terrane. Paleocurrent data document an overall eastward flow direction. Up-section coarsening of the Geste Formation suggests that topographic relief in the source area increased through time, possibly owing to enhanced tectonic activity and source terrane unroofing. Sandstone petrography and conglomerate clast-count data document quartzose and phyllitic compositions typical of Ordovician rocks preserved just west of the Salar de Pastos Grandes area. Paleocene-Eocene detrital apatite fission track age populations (P1: ˜35-52 Ma; P2: ˜52-65 Ma) of the Geste Formation and their consistent trends up-section suggest moderate to rapid (˜0.4 mm/a to >1 mm/a) exhumation of western sediment sources during the early to mid-Tertiary stages of Andean mountain building. Sedimentation rates increase up-section from ˜0.1 mm/a to 1 mm/a. Our data, when combined with other structural, stratigraphic and seismic evidence from surrounding regions, suggest that the Geste Formation was deposited in response to crustal shortening and resulting erosion and sedimentation, which started as early as Cretaceous in the Chilean Cordillera de Domeyko and in the Salar de Pastos Grandes area by Eocene time. The Geste Formation could be interpreted either as a local wedge-top accumulation on the eastward propagating central Andean orogenic wedge, or as a local intermontane basin. The similarities between wedge-top deposits preserved in Bolivia and Eocene deposits in northwestern Argentina, south of ˜25°S, lead us to favor the wedge-top scenario for the Geste Formation. If correct, this implies that the deformation front of the Andean orogenic wedge incorporated both thin- and thick-skinned structures as it migrated, possibly unsteadily, from the Cordillera de Domeyko during the Cretaceous-Paleocene to areas within the Puna and Eastern Cordillera by mid-late Eocene time. Contemporaneously, a regional-scale foreland basin system developed over an along-strike distance of at least 650 km.

Carrapa, B.; Decelles, P. G.

2008-02-01

27

Study of the Comet C/2013 A1 (Siding Spring)  

NASA Astrophysics Data System (ADS)

The comet called C/2013 A1 (SIDING SPRING) was discovered on January 3, 2013 in Australia. In January 28/2014, NASA announced that is preparing for the close encounter that will happen between the comet C/2013 A1 and Mars on October 19-2014. The Mission called “MAVEN” will insert in Mars orbit on september 21—2014. The comet will pass just 138,000 kilometers far from the surface of Mars. The probability that the comet collides with Mars is small but the dust particles emitted by the comet can cause damage to spacecrafts and probes that are in orbit around that planet. NASA is making preparations to take all precautions. If the comet is quite active, there will be almost no time to take security measures with Mars orbiters. For that reason NASA is already ahead of the facts. According to scientists of the "JET PROPULSION LABORATORY-JPL", dust particles spewing from the comet may be traveling at 56 km / sec in relation to the orbiters, fifty times faster than the speed of a bullet. From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during several days. The pictures of the asteroid were captured with the following equipment: CGE PRO 1400 CELESTRON (f/11 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera. Astrometry was carried out, and we calculated the orbital elements.Summary And Conclusions: We obtained the following orbital parameters: eccentricity = 1.0003983, orbital inclination = 129.03078 deg, longitude of the ascending node = 300.99538 deg, argument of perihelion = 2.42310 deg, perihelion distance = 1.40023196 A.U. The parameters were calculated based on 20 observations (Jan 21 to April 02) with mean residual = 0.334 arcseconds. We also obtained the light curve of the body with our data (January to November/2014)Acknowledgements: The authors would like to thank to University of Narino-Pasto-Colombia.

Vodniza, Alberto Q.; Pereira, Mario R.

2014-11-01

28

Management of pest mole crickets in Florida and Puerto Rico with a nematode and parasitic wasp  

SciTech Connect

Non-indigenous invasive mole crickets, Scapteriscus vicinus Scudder (Orthoptera: Gryllotalpidae) in Florida and S. didactylus (Latreille) (the 'changa') in Puerto Rico, are being managed with an entomopathogenic nematode, Steinernema scapterisci (Nguyen and Smart) (Rhabditida: Steinernematidae), and a parasitic wasp, Larra bicolor L. (Hymenoptera: Sphecidae). Pest mole cricket populations have declined by 95% in north central Florida since these specialist natural enemies were released and established in the 1980s. Commercial production of the nematode was initiated, nearly 70 billion were applied in 34 Florida counties, and their establishment, spread, and impact on mole crickets were monitored. The infected mole crickets dispersed the nematode rapidly, so that within 6 months these parasites were present in most of the insects trapped in experimental pastures. Three years later, mole cricket populations were reduced to acceptable levels and the bahiagrass had recovered. The nematode was released for the first time in Puerto Rico during 2001 and has persisted; the wasp was introduced in the late 1930s. The geographical distribution of the wasp is being expanded in Florida and Puerto Rico by planting plots of Spermacoce verticillata (L.), a wildflower indigenous to Puerto Rico and widely distributed in southern Florida. Pastures, sod farms, golf courses, landscapes, and vegetable farms in Florida and Puerto Rico are benefiting from biological control of invasive mole crickets. (author) [Spanish] Los grillotopos invasores no indigenas, Scapteriscus vicinus (Orthoptera: Gryllotalpidae) en el estado de Florida y S. didactylus ('changa') en Puerto Rico, estan siendo manejados por el nematodo entomopathogeno, Steinernema scapterisci (Rhabditida: Steinernematidae) y la avispa parasitica, Larra bicolor (Hymenoptera: Sphecidae). Las poblaciones de los grillotopo plagas han declinado un 95% en el norte central de la Florida desde que estos enemigos naturales especialistas fueron liberados y establecidos en los 80s. Consecuentemente, la produccion comercial del nematodo fue iniciada, casi 70 billones fueron aplicados en 34 condados de la Florida, y se realizo un monitoreo para evaluar su establecimiento, dispersion e impacto sobre los grillotopos. Los gillotopos infectados dispersaron los nematodos rapidamente, tanto que despues de 6 meses estos parasitos estaban presentes en la mayoria de los insectos atrapados en los pastos experimentales. Tres anos despues, las poblaciones de los grillotopos fueron reducidas a niveles aceptables y los campos de pasto 'bahia' se recuperaron. El nematodo fue liberado para la primera vez en Puerto Rico durante del 2001 y ha persistido; la avispa fue introducida al final de los 30s. La distribucion geografica de la avispa se esta extendiendo en la Florida y Puerto Rico por medio de la siembra de parcelas de Spermacoce verticillata, una flor silvestre indigena a Puerto Rico y distribuida ampliamente en el sur de la Florida. Los campos de pasto, las operaciones comerciales de cesped, los campos de golf, los paisajes y las fincas de hortalizas en la Florida y Puerto Rico se estan beneficiando del control biologico de los grillotopos invasores. (author)

Leppla, N.C.; Frank, J.H. [University of Florida, Institute of Food and Agricultural Sciences, Department of Entomology and Nematology, P.O. Box 110630, Gainesville, FL 32611-0630 (United States); Adjei, M.B. [University of Florida, Range Cattle Research and Education Center, 3401 Experiment Station, Ona, FL 33865-9706 (United States); Vicente, N.E. [University of Puerto Rico, Agricultural Experiment Station, P.O. Box 9030, Mayaguez, PR 00681-9030 (Puerto Rico)

2007-03-15

29

Invertebrate fauna associated with Torpedograss, Panicum repens (Cyperales: Poaceae), in Lake Okeechobee, Florida, and prospects for biological control  

SciTech Connect

Torpedograss, Panicum repens L., is an adventive, rhizomatous grass species that has become an invasive weed of terrestrial, wetland, and aquatic environments in tropical and subtropical regions worldwide. Until recently, strategies for controlling torpedograss in the USA have focused almost exclusively on mechanical and chemical methods, either alone or in combination, with varied results. A survey of the arthropods and nematodes currently associated with the plant in Lake Okeechobee, Florida, was conducted as part of a feasibility study to determine whether torpedograss is an appropriate target for a classical biological control program. Overall, approximately 4,000 arthropods and 400 nematode specimens were collected. Sweep, clipped vegetation, and soil core samples were dominated by representatives of the arthropod orders Hemiptera, Hymenoptera, Diptera, and Acari. Lesion nematodes of the genus Pratylenchus were commonly associated with the roots of torpedograss. None of the organisms collected were torpedograss specialists. Although classical biological control of torpedograss is feasible based on the extent of the infestation, economic losses, resistance to conventional controls, and the report of a potentially host specific natural enemy in India, the botanical position of this grass weed will require a formal risk assessment before proceeding with a classical biological control program. (author) [Spanish] La conota, Panicum repens L., es una especie foranea de pasto que produce rizomas que ha convertido en ser una maleza invasora de ambientes terrestres, pantanosos y acuaticos en regiones tropicales y subtropicales en todo el mundo. Hasta hace un tiempo reciente, las estrategias para controlar conota en los EEUU eran enfocadas casi exclusivamente en los metodos mecanicos y quimicos, solos o en combinacion, con resultados variables. Un muestreo de los artropodos y nematodos asociados corrientemente con esta planta en el Lago de Okeechobee, Florida, fue realizado como parte de un estudio de factibilidad para determinar si conota es una candidata apropiada para un programa de control biologico clasico. En general, especimenes de aproximadamente unos 4,000 artropodos y unos 400 nematodos fueron recolectados. Muestras recolectadas pasando una red sobre vegetacion mezclada, cortando la vegetacion y tomando centros del suelo fueron dominados por representantes de artropodos de los ordenes de Hemiptera, Hymenoptera, Diptera, y Acari. Nematodos en el genero Pratylenchus, que causan lesiones sobre tejido, fueron asociados regularmente con las raices de conota. Ninguno de los organismos recolectados eran especialistas sobre conota. Aunque el control biologico clasico de la conota es factible basado sobre la magnitud de la infestacion, las perdidas economicas, la resistencia hacia los metodos de control convencionales y el informe en la India de un posible enemigo natural especifico a esta planta, la posicion botanica de este pasto maleza requiere una evaluacion de riesgo economico formal antes de continuar con un programa de control biologico clasico. (author)

Cuda, J.P.; Dunford, J.C.; Leavengood, J.M. Jr. [University of Florida, Entomology and Nematology Department, Gainesville, FL 32611-0620 (United States)

2007-03-15

30

14C ages and activity for the past 50 ka at Volca??n Galeras, Colombia  

USGS Publications Warehouse

Volca??n Galeras is the southernmost Colombian volcano with well-recorded historic activity. The volcano is part of a large and complex volcanic center upon which 400,000 people live. Historic activity has centered on a small-volume cone inside the youngest of several large amphitheaters that breach the west flank of the volcano, away from the city of Pasto (population 300,000). Lava flows (SiO2 between 54.6 and 64.7 wt.%) have dominated activity for more than 1 Ma, but explosive events have also occurred. Joint studies by volcanologists from Colombia, Ecuador, Peru, Bolivia, Argentina, and the United States produced 24 new 14C ages and more than 100 stratigraphic sections to interpret the past 50 ka of activity at Galeras, including sector collapse events. The youngest collapse event truncated 12.8 ka lava flows and may have occurred as recently as 8 to 10 ka. Tephra-fall material rapidly thins and becomes finer away from the vent area. The only widespread marker in the < 10 ka section is a biotite-bearing tephra deposited between 4.1 and 4.5 ka from a source south of Galeras. It separates cryoturbated from largely undisturbed layers on Galeras, and thus dates a stratigraphic horizon which is useful in the interpretation of other volcanoes and geotectonics in the equatorial Andes. Pyroclastic flows during the past 50 ka have been small to moderate in volume, but they have left numerous thin deposits on the north and east flanks where lava flows have been impeded by crater and amphitheater walls. Many of the pyroclastic-flow deposits are lithic rich, with fines and clasts so strongly altered by hydrothermal action before eruption that they, as well as the sector collapse deposits, resemble waste dumps of leached cappings from disseminated sulfide deposits more than volcanogenic deposits. This evidence of a long-lived hydrothermal system indicates susceptibility to mass failure and explosive events higher than expected for a volcano built largely by lava flows and modest Vulcanian eruptions. Photographs, written accounts, and our study document historic north and east flank pyroclastic flows as far as 10 km from the summit; however, none have left recognizable deposits in Pasto for more than 40 ka.

Banks, N.G.; Calvache, V.M.L.; Williams, S.N.

1997-01-01

31

Study of 2003 YT1 Asteroid  

NASA Astrophysics Data System (ADS)

The asteroid 2003 YT1 was at approximately 25 million kilometers from the Earth on May 05-2011 (U.T) [1]. It has an orbital period of 1.17 years and it was estimated to have a size of 2.63 kilometers [2]. From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during three days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS [3]. Our observatory's code at the MPC is "H78". Pictures of the asteroid were captured with the following equipment: 14" LX200 GPS MEADE (f/10 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera. This asteroid has a rotation period of 2.343 hours [4] and its binary nature was noted by the Modra and Ondrejov Observatories independently [5]. Nolan used radar observations to determine that this is a binary with sizes of approximately 1 and 0.2 km and primary rotation period of P < 2.6 h [6]. The asteroid will be at approximately 0.0348 A.U from the Earth on October 31-2016 and at approximately 0.0113 A.U from the Earth on October 31-2016 [7]. Astrometry was carried out, and we calculated the orbital elements. It was designed a computing program on Visual Basic 6.0. SPACEWEATHER published our video of 2003YT1 on May 5/2011 [8].

Vodniza, A. Q.; Rojas, M.

2011-10-01

32

Residents, Decision Makers, and Scientists Discuss Volcanic Hazard in Colombia  

NASA Astrophysics Data System (ADS)

Knowledge Sharing and Collaboration in Volcanic Risk Mitigation at Galeras Volcano, Colombia; Pasto, Colombia, 6-11 July 2009; Galeras volcano, located in southwestern Colombia, imposes several hazards on the surrounding population: pyroclastic flows, lahars, ashfall, and shock waves. The current hazard map shows three zones: high, medium, and low (see A. D. Hurtado Artunduaga and G. P. Cortés Jiménez, J. Volcanol. Geotherm. Res., 77, 89-100, 1997). The pyroclastic flow hazard on this map defines the Zone of High Volcanic Hazard (ZAVA) for civil authorities. Current activity of Galeras has provoked two contentious issues related to hazard management: (1) Decision makers announce an evacuation order of ZAVA whenever the volcanic alert reaches a high level, and (2) the Colombian government initiated a relocation program for the inhabitants within ZAVA (Colombian Decrees-Laws 4106 and 3905). However, communities within ZAVA refuse to obey both the evacuation orders and the relocation process. To help resolve this situation, the University of Nariño (Colombia) and the State University of New York at Buffalo organized a workshop, which was sponsored by the U.S. National Science Foundation. A daily average of 92 people attended, including residents of ZAVA, decision makers, Colombian technical and scientific personnel, international scientists and researchers, students, and academics from the University of Nariño.

Sheridan, Michael F.; Cordoba, Gustavo

2010-02-01

33

New Luminescence Ages for the Galer?a Complex Archaeological Site: Resolving Chronological Uncertainties on the Acheulean Record of the Sierra de Atapuerca, Northern Spain  

PubMed Central

The archaeological karstic infill site of Galería Complex, located within the Atapuerca system (Spain), has produced a large faunal and archaeological record (Homo sp. aff. heidelbergensis fossils and Mode II lithic artefacts) belonging to the Middle Pleistocene. Extended-range luminescence dating techniques, namely post-infrared infrared stimulated luminescence (pIR-IR) dating of K-feldspars and thermally transferred optically stimulated luminescence (TT-OSL) dating of individual quartz grains, were applied to fossil-bearing sediments at Galería. The luminescence dating results are in good agreement with published chronologies derived using alternative radiometric dating methods (i.e., ESR and U-series dating of bracketing speleothems and combined ESR/U-series dating of herbivore teeth), as well as biochronology and palaeoenvironmental reconstructions inferred from proxy records (e.g., pollen data). For the majority of samples dated, however, the new luminescence ages are significantly (?50%) younger than previously published polymineral thermoluminescence (TL) chronologies, suggesting that the latter may have overestimated the true burial age of the Galería deposits. The luminescence ages obtained indicate that the top of the basal sterile sands (GIb) at Galería have an age of up to ?370 thousand years (ka), while the lowermost sub-unit containing Mode II Acheulean lithics (base of unit GIIa) was deposited during MIS 9 (mean age?=?313±14 ka; n?=?4). The overlying units GIIb-GIV, which contain the richest archaeopalaeontological remains, were deposited during late MIS 8 or early MIS 7 (?240 ka). Galería Complex may be correlative with other Middle Pleistocene sites from Atapuerca, such as Gran Dolina level TD10 and unit TE19 from Sima del Elefante, but the lowermost archaeological horizons are ?100 ka younger than the hominin-bearing clay breccias at the Sima de los Huesos site. Our results suggest that both pIR-IR and single-grain TT-OSL dating are suitable for resolving Middle Pleistocene chronologies for the Sierra de Atapuerca karstic infill sequences. PMID:25338076

Demuro, Martina; Arnold, Lee J.; Pares, Josep M.; Perez-Gonzalez, Alfredo; Ortega, Ana I.; Arsuaga, Juan L.; Bermudez de Castro, Jose M.; Carbonell, Eudald

2014-01-01

34

Continuity or discontinuity in the European Early Pleistocene human settlement: the Atapuerca evidence  

NASA Astrophysics Data System (ADS)

The nature, timing, pattern, favourable circumstances and impediments of the human occupation of the European continent during the Early Pleistocene are hot topics in Quaternary studies. In particular, the problem of the (dis) continuity of the settlement of Europe in this period is an important matter of discussion, which has been approached in the last decade from different points of view. The Gran Dolina (TD) and Sima del Elefante (TE) cave sites in the Sierra de Atapuerca, (Spain) include large and quasi-continuous stratigraphic sequences that stretch back from at least 1.2 million years ago (Ma) to the Matuyama/Brunhes boundary. The archaeological and paleontological record from these sites can help to test different hypotheses about the character of the human settlement in this region and period. Furthermore, the TD6 level has yielded a large collection of human fossil remains attributed to Homo antecessor. According to different geochronological methods, as well as to paleomagnetic and biostratigraphical analyses, these hominins belong to an age range of 0.96-0.80 Ma. Unfortunately, the finding in 2007 of some human fossil remains in the TE9 level, dated to about 1.22 Ma, was not enough to conclude whether H. antecessor had deep roots in the European Early Pleistocene. A set of derived features of H. antecessor shared with both the Neanderthal lineage and modern humans suggests that this species is related, and not far, from the most recent common ancestor (MRCA) of Homo neanderthalensis and Homo sapiens. If we assume that there was a lineal biological relationship between the TE9 and TD6 hominins, we should reconsider many of the conclusions achieved in previous paleontological and genetic studies. In addition, we would be obliged to build a highly complicated paleogeographical scenario for the origin of the MRCA. Although continuity in the settlement of Europe during the entire late Early Pleistocene is not discarded (e.g. in refuge areas), it seems that this Western extreme of Eurasia, and the Iberian Peninsula in particular, was occupied by at least two different hominin populations.

Bermúdez de Castro, José María; Martinón-Torres, María; Blasco, Ruth; Rosell, Jordi; Carbonell, Eudald

2013-09-01

35

One million years of cultural evolution in a stable environment at Atapuerca (Burgos, Spain)  

NASA Astrophysics Data System (ADS)

The present paper analyses the evidence provided by three sites (Sima del Elefante, Gran Dolina, and Galería) located in the Trinchera del Ferrocarril of the Sierra de Atapuerca. These three sites are cave infillings that contain sediments deposited from approximately 1.2 Ma to 200 kyr. Pollen, herpetofauna, and small and large mammal remains are used as proxies to obtain a general picture of the environmental changes that occurred at the Sierra de Atapuerca throughout the one million-year period represented at these sites. Similarly, cultural changes are tracked analyzing the evidence of human behavior obtained from the study of several bone and lithic assemblages from these three sites. At least three periods with different cultural features, involving technology, subsistence and behavior, are determined from the available evidence. The first two periods correspond to the Mode 1 technology and Homo antecessor: the first is dated around 1.2 to 1.0 Ma and reflects opportunistic behavior both in technology and subsistence. The second period is around 800 kyr BP. Mode 1 technology is still maintained, but subsistence strategies include systematic hunting and the use of base camps. The third period is dated between 500 ka and 200 ka and corresponds to the Mode 2 technology and the acquisition of directional hunting and other organizational strategies by Homo heidelbergensis. A transition from Mode 2 to Mode 3 seems to appear at the end of this time-range, and may reflect the early phases of a fourth cultural change. With regard to the environment, our main conclusion is that there was an absence of extremely harsh conditions at Atapuerca throughout this time period. The presence of Mediterranean taxa was constant and the dominant landscape was a savannah-like open environment, probably with small forest patches. An alternation of Mediterranean and mesic species as the dominant component of the tree storey was induced by the climatic cycles, and steppes spread across the landscape during the drier periods. In any case, it is not possible to establish clear cut-off points separating entirely different environmental episodes. Our results show no evidence of any relationship between environmental change and cultural change at the Sierra de Atapuerca.

Rodríguez, J.; Burjachs, F.; Cuenca-Bescós, G.; García, N.; Van der Made, J.; Pérez González, A.; Blain, H.-A.; Expósito, I.; López-García, J. M.; García Antón, M.; Allué, E.; Cáceres, I.; Huguet, R.; Mosquera, M.; Ollé, A.; Rosell, J.; Parés, J. M.; Rodríguez, X. P.; Díez, C.; Rofes, J.; Sala, R.; Saladié, P.; Vallverdú, J.; Bennasar, M. L.; Blasco, R.; Bermúdez de Castro, J. M.; Carbonell, E.

2011-06-01

36

Study of 2005 YU55 Asteroid  

NASA Astrophysics Data System (ADS)

The asteroid 2005 YU55 was at approximately 2.3 million kilometers from the Earth on April 19-2010. It has an orbital period of 1.22 years and it was initially estimated to have a size of about 200 meters. From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during three days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS. (Our observatory's code at the MPC is "H78"). We obtained the following orbital parameters: eccentricity = 0.4305536, semi-major axis = 1.14243012 A.U, orbital inclination = 0.51093 deg, longitude of the ascending node = 39.38940 deg, argument of perihelion = 268.90355 deg, orbital period = 1.22 years, mean motion = 0.80715994 deg/d, perihelion distance = 0.65055263 A.U, aphelion distance = 1.63430762 A.U. The parameters were calculated based on 22 observations (2010 Apr. 16-19) with RMS error = 0.629 arcseconds. Pictures of the asteroid were captured with the following equipment: 14” LX200 GPS MEADE (f/10 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera. The Radiotelescope of Arecibo found that its shape is roughly spherical and of about 400 meters in diameter, larger than the initially assumed. At a time the asteroid was classified as a potential threat and on February 2010 it was rated with a value of 1 on the Torino scale, but later, on April 2010, based on new data supplied by observatories of the world it was downgraded to value 0. With the new asteroid's orbital data and radar studies made by the Arecibo Radiotelescope (April 19 thru 21) is well known that in 100 years there will be no impact on Earth. The asteroid will be at approximately 324,200 kilometers from the Earth on November 8-2011.

Vodniza, Alberto Q.; Pereira, M. R.

2010-10-01

37

Evaluating the X chromosome-specific diversity of Colombian populations using insertion/deletion polymorphisms.  

PubMed

The European and African contribution to the pre-existing Native American background has influenced the complex genetic pool of Colombia. Because colonisation was not homogeneous in this country, current populations are, therefore, expected to have different proportions of Native American, European and African ancestral contributions. The aim of this work was to examine 11 urban admixed populations and a Native American group, called Pastos, for 32 X chromosome indel markers to expand the current knowledge concerning the genetic background of Colombia. The results revealed a highly diverse genetic background comprising all admixed populations, harbouring important X chromosome contributions from all continental source populations. In addition, Colombia is genetically sub-structured, with different proportions of European and African influxes depending on the regions. The samples from the North Pacific and Caribbean coasts have a high African ancestry, showing the highest levels of diversity. The sample from the South Andean region showed the lowest diversity and significantly higher proportion of Native American ancestry than the other samples from the North Pacific and Caribbean coasts, Central-West and Central-East Andean regions, and the Orinoquian region. The results of admixture analysis using X-chromosomal markers suggest that the high proportion of African ancestry in the North Pacific coast was primarily male driven. These men have joined to females with higher Native American and European ancestry (likely resulting from a classic colonial asymmetric mating type: European male x Amerindian female). This high proportion of male-mediated African contributions is atypical of colonial settings, suggesting that the admixture occurred during a period when African people were no longer enslaved. In the remaining regions, the African contribution was primarily female-mediated, whereas the European counterpart was primarily male driven and the Native American ancestry contribution was not gender biased. PMID:24498042

Ibarra, Adriana; Restrepo, Tomás; Rojas, Winston; Castillo, Adriana; Amorim, António; Martínez, Beatriz; Burgos, German; Ostos, Henry; Álvarez, Karen; Camacho, Mauricio; Suarez, Zuleyma; Pereira, Rui; Gusmão, Leonor

2014-01-01

38

The Cerro Aguas Calientes caldera, NW Argentina: an example of a tectonically controlled, polygenetic, collapse caldera, and its regional significance  

NASA Astrophysics Data System (ADS)

Polygenetic, silicic collapse calderas such as Cerro Galán, Pastos Grandes, La Pacana, Vilama, Negra Muerta, Farallón Negro, Cerro Guacha, among others are common in the central Andes. Here we describe in detail the Cerro Aguas Calientes caldera in NW Argentina, which comprises two caldera-forming episodes occurred at 17.15 Ma and 10.3 Ma, respectively. We analyse the significance of its structural setting, composition, size and the subsidence style of both caldera episodes. Our results reveal that the caldera eruptions had a tectonic trigger. In both cases, an homogeneous dacitic crystal-rich (>60 vol. % of crystals) reservoir of batholitic size became unstable due to the effect of increasing regional transpression, favouring local dilation throughout minor strike slip faults from which ring faults nucleated and permitted caldera collapse. Both episodes are similar in shape, location and products of the resulting calderas. The 17.15 Ma caldera has an elliptical shape (17 × 14 km) and is elongated in a N30° trend; both intracaldera and extracaldera ignimbrites covered an area of around 620 km2 with a minimum volume estimate of 138 km3 (DRE). The 10.3 Ma episode generated another elliptical caldera (19 ×14 km), with the same orientation as the previous one, from which intracaldera and outflow ignimbrites covered a total area of about 1,700 km2, representing a minimum eruption volume of 341 km3 (DRE). In this work we discuss the significance of the Cerro Aguas Calientes caldera in comparison with other well known examples from the central Andes in terms of tectonic setting, eruption mechanisms, and volumes of related ignimbrites. We suggest that our kinematic model is a common volcano-tectonic scenario during the Cenozoic in the Puna and Altiplano, which may be applied to explain the origin of other large calderas in the same region.

Petrinovic, Ivan A.; Martí, Joan; Aguirre-Diaz, Gerardo J.; Guzmán, Silvina R.; Geyer, Adelina; Grosse, Pablo; Salado Paz, Natalia

2010-05-01

39

Evaluating the X Chromosome-Specific Diversity of Colombian Populations Using Insertion/Deletion Polymorphisms  

PubMed Central

The European and African contribution to the pre-existing Native American background has influenced the complex genetic pool of Colombia. Because colonisation was not homogeneous in this country, current populations are, therefore, expected to have different proportions of Native American, European and African ancestral contributions. The aim of this work was to examine 11 urban admixed populations and a Native American group, called Pastos, for 32 X chromosome indel markers to expand the current knowledge concerning the genetic background of Colombia. The results revealed a highly diverse genetic background comprising all admixed populations, harbouring important X chromosome contributions from all continental source populations. In addition, Colombia is genetically sub-structured, with different proportions of European and African influxes depending on the regions. The samples from the North Pacific and Caribbean coasts have a high African ancestry, showing the highest levels of diversity. The sample from the South Andean region showed the lowest diversity and significantly higher proportion of Native American ancestry than the other samples from the North Pacific and Caribbean coasts, Central-West and Central-East Andean regions, and the Orinoquian region. The results of admixture analysis using X-chromosomal markers suggest that the high proportion of African ancestry in the North Pacific coast was primarily male driven. These men have joined to females with higher Native American and European ancestry (likely resulting from a classic colonial asymmetric mating type: European male x Amerindian female). This high proportion of male-mediated African contributions is atypical of colonial settings, suggesting that the admixture occurred during a period when African people were no longer enslaved. In the remaining regions, the African contribution was primarily female-mediated, whereas the European counterpart was primarily male driven and the Native American ancestry contribution was not gender biased. PMID:24498042

Ibarra, Adriana; Restrepo, Tomas; Rojas, Winston; Castillo, Adriana; Amorim, Antonio; Martinez, Beatriz; Burgos, German; Ostos, Henry; Alvarez, Karen; Camacho, Mauricio; Suarez, Zuleyma; Pereira, Rui; Gusmao, Leonor

2014-01-01

40

The Asteroid 1998 QE2  

NASA Astrophysics Data System (ADS)

This big asteroid was at 5.8 millions of kilometers from the Earth on May 31 (2013) and it has a diameter of 2.7 km. The radar images obtained by JPL showed that the period of rotation around its axis is close to five hours. Hills. K (2013) reported that the period is of 5.281 +/- 0.002 hours. On June 4 the team of Goldstone-Arecibo found a period of 4.75 +/- 0.01 hours. We also contributed with the light and phase curves to estimate the period by means of the telescope (with red filter). The radar imagery (JPL and Arecibo) revealed that 1998 QE2 has a moon, and we captured a mutual event (eclipse). From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during several days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS. The pictures of the asteroid were captured with the following equipment: CGE PRO 1400 CELESTRON (f/11 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera. We obtained the light curve of the body. Astrometry was carried out, and we calculated the orbital elements. We obtained the following orbital parameters: eccentricity = 0.5692181, semi-major axis = 2.41104631 A.U, orbital inclination = 12.82771 deg, longitude of the ascending node = 250.16876 deg, argument of perihelion = 345.61328 deg, mean motion = 0.26326658 deg/d, perihelion distance = 1.03863508 A.U, aphelion distance = 3.78345755 A.U. The asteroid has an orbital period of 3.74 years The parameters were calculated based on 191 observations (2013 May: 17-24) with mean residual = 0.162 arcseconds. A video of the asteroid from our Observatory was published on the main page of the “SPACEWEATHER” web: http://www.spaceweather.com/archive.php?view=1&day=21&month=05&year=2013 Note: The autors would like to thank to: Dr. Alessondra Springmann (Arecibo Observatory), Dr. Petr Pravec (Czech Republic), Dr. Lance Benner (JPL), Dr. Carl Hergenrother (Target Asteroids Team), and Dr. Dolores Hill (Target Asteroids Team) for their special suggestions.

Vodniza, Alberto Q.; Pereira, M. R.; Arecibo Observatory Team; JPL Target Asteroids Team

2013-10-01

41

The Asteroid 2000 ET70  

NASA Astrophysics Data System (ADS)

The asteroid 2000 ET70 (162421) was discovered by Lincoln Laboratory ETS (LINEAR) in New Mexico on March 8, 2000. Whiteley (2001) classified 2000 ET70 as an X-type object: This asteroid belongs to an ambiguous group that includes objects that are large and dark, metallic.The composition of this asteroid is unknown.The asteroid was at 0.0454430 U.A from the Earth on February 19.85956 (2012) and it will be at approximately 0.1503270 A.U from the Earth on August 21.07061 (2012).The asteroid 2000 ET70 was studied by radar in Arecibo and Goldstone. Shantanu Naidu and Jean-Luc Margot studied this object by Arecibo radar (Feb 13-2012) and they suggest that 2000 ET70 is roughly 1.5 km in diameter and that it has a period of rotation of about 9.5 hours. It has an orbital period of 0.92 years.From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during three days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS. Our observatory’s code at the MPC is “H78”. Pictures of the asteroid were captured with the following equipment: 14” LX200 GPS MEADE (f/10 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera.Astrometry was carried out, and we calculated the orbital elements. We obtained the following orbital parameters: eccentricity = 0.1243231, semi-major axis = 0.94541495 A.U, orbital inclination = 22.32919 deg, longitude of the ascending node = 331.05007 deg, argument of perihelion = 45.20913 deg, orbital period = 0.92 years (335.76 days), mean motion = 1.07218658 deg/d, perihelion distance = 0.82787796 A.U, aphelion distance = 1.06295195 A.U. The parameters were calculated based on 71 observations (2012 Mar. 1-7) with mean residual = 0.262 arcseconds.

Vodniza, Alberto Q.; Pereira, M. R.

2012-10-01

42

Paleoelevation of the Puna Plateau, northwestern (NW) Argentina inferred from deuterium isotopic analyses of volcanic glass  

NASA Astrophysics Data System (ADS)

Evidence for recent uplift (? 10 Ma) of the Andes has largely come from study of the Altiplano in Bolivia. However, this region represents only a portion of the Andes and is geographically distinct from the Puna Plateau to the south, which is significantly higher and drier than the Altiplano. The Altiplano today is topographically smooth, whereas the Puna Plateau contains numerous intermontane basins, resulting in more regional climate variability. In addition, the two regions exhibit unique structural deformation and volcanic geochemistry, suggesting an overall more complex uplift history. Previous geochemical studies suggest that the Altiplano in Bolivia has been characterized by a high magnitude plateau event ca. 10 - 6 Ma. (Garzione et al., 2008) Alternatively, more recent climate modeling has suggested a gradual uplift history of the Andes beginning at around 25 Ma. (Ehlers and Poulsen, 2009) No geochemical proxies for paleoaltimetry exists farther south in the Puna Plateau of NW Argentina. To resolve possible differences in uplift history between the Altiplano and the Puna Plateau, we collected volcanic tuff and ignimbrite samples spanning the early Miocene to Recent from across the Puna Plateau (between 24° and 28° south latitude; Arizaro basin and Pasto Ventura region) of NW Argentina. Hydrated volcanic glass has been shown to retain the isotopic signature of meteoric waters once fully hydrated (thought to occur <10 3 yrs). We used the ?D values of hydrated volcanic glass as an elevation proxy because meteoric waters are determined by precipitation, which becomes more depleted in ?D with gain in elevation. Since aridity and temperature also influence the isotopic composition of meteoric water, plant microfossil and sedimentological evidence was collected to help understand the potential effects of both regional climate variability and elevation on our isotope results. Age control for our ?D values is based on zircon U-Pb dating of the same volcanic samples. ?D values of modern precipitation across NW Argentina decrease by about 1.8‰/100m. In order to apply this lapse rate to our data and infer a paleoelevation, we must assume that water within the glass was not reset diagenetically by more recent meteoric water, regional climate stayed constant and atmospheric circulation patterns remained constant. Under these assumptions, our results show a 19.5 Ma tuff with ?D values close to that of modern precipitation at the Puna Plateau’s current elevation (~4.4 km). With the addition of isotopic data from recently collected tuff of the late Eocene to Recent stratigraphic record in the Antofalla basin, we will be able to test whether these early Miocene glass samples have been reset to modern meteoric water values or truly reflect the paleoelevation history of the Andes.

Canavan, R.; Clementz, M. T.; Carrapa, B.; Quade, J.; Decelles, P. G.; Schoenbohm, L. M.; Boyd, J.

2010-12-01

43

Application of Vegetation Indices to Estimate Acorn Production at Iberian Peninsula  

NASA Astrophysics Data System (ADS)

The Iberian pig valued natural resources of the pasture when fattened in mountain. The variability of acorn production is not contained in any line of Spanish agricultural insurance. However, the production of arable pasture is covered by line insurance number 133 for loss of pasture compensation. This scenario is only contemplated for breeding cows and brave bulls, sheep, goats and horses, although pigs are not included. This insurance is established by monitoring ten-day composites Normalized Difference Vegetation Index (NDVI) measured by satellite over treeless pastures, using MODIS TERRA satellite. The aim of this work is to check if we can use a satellite vegetation index to estimate the production of acorns. In order to do so, two Spanish grassland locations have been analyzed: regions of Olivenza (Jerez-Oliva) and Merida (Badajoz). The acorns production was evaluated through 2002-2005 gauging conducted by the Grupo Habitat de la Orden (Badajoz). Medium resolution (500x500 m2) MODIS images were used during the same time period to estimate the ten-day composites NDVI at these locations. Finally, meteorological data was obtained from SIAR and MAGRAMA network stations, calculating the ten-day averaged temperature and ten day accumulated precipitation. Considering two accumulated factors, NDVI and temperature, three phenological stages were well defined being the second one which pointed differences among campaigns. Then, accumulated precipitation versus accumulated NDVI was plot for this second phenological stage obtaining maximum differences at 300 mm of cumulative rainfall. Analyzing acorn production with accumulated NDVI in that moment a production function was obtained with a correlation coefficient of 0.71. These results will be discussed in detail. References J.A. Escribano, C.G.H. Diaz-Ambrona, L. Recuero, M. Huesca, V. Cicuendez, A. Palacios-Orueta y A.M. Tarquis. Aplicacion de Indices de Vegetacion para evaluar la falta de produccion de pastos y montaneras en dehesas. I Congreso Iberico de la Dehesa y el Montado. 6-7 Noviembre, 2013, Badajoz. J.A. Escribano Rodriguez, A.M. Tarquis, C.G. Hernandez Diaz-Ambrona. Pasture Drought Insurance Based on NDVI and SAVI. Geophysical Research Abstracts, 14, EGU2012-13945, 2012. EGU General Assembly 2012. Juan Escribano Rodriguez, Carmelo Alonso, Ana Maria Tarquis, Rosa Maria Benito, Carlos Hernandez Diaz-Ambrona. Comparison of NDVI ?elds obtained from different remote sensors. Geophysical Research Abstracts, 15, EGU2013-14153, 2013. EGU General Assembly 2013 Acknowledgements. This work was partially supported by ENESA under project P10 0220C-823.

Escribano, Juan A.; Díaz-Ambrona, Carlos G. H.; Recuero, Laura; Huesca, Margarita; Cicuendez, Victor; Palacios, Alicia; Tarquis, Ana M.

2014-05-01

44

N-P-K balance in a milk production system on a C. nlemfuensis grassland and a biomass bank of P. purpureum CT-115 clone  

NASA Astrophysics Data System (ADS)

In very intensive milk production systems in Europe and America with the use of high amounts of chemical fertilizers, the nutrient recycling models consider the losses by leaching and N volatilization, as well as the hydro physical characteristics of the soil affecting the performance of this element (10; 6). However, in more extensive milk production systems, low input agriculture forming the natural cycle occurring within each farm, is of vital importance to potentate nutrient recycling for a stable animal production. The objective is the determination of the values of N, P and K inputs and outputs in a dairy farm with a sward composed by 60% of C. nlemfuensis and 40% of P. purpureum CT-115, associated with legumes in 28% of the area and the balance of these nutrients in the system using the "Recycling" software proposed by Crespo et al (2007). The grassland covered an area of 53.4 ha, composed by C. nlemfuensis (60%), P. purpureum CT-115 (40%) and L. leucocephala and C. cajan legumes intercropped in 28% of the area. The dairy herd consisted of 114 cows, 35 replacement heifers and 24 calves. There was a milk yield of 100 000 litters and the animals consumed 825 t DM from pastures and 75.1 t DM from other supplementary feeds. Nutrients extracted by pastures, nutrients intake by animals from pastures, symbiotically N fixation by legumes and N, P and K determinations outside the system due to animal production were determined (3-11). Volatilized ammonia, nutrient input and litter accumulated in the paddocks were measured once each season of the year. In the whole system the balance indicates negative values of N, P and K. Out of the total amount of nutrients consumed, animals used only 16 kg N, 5 Kg P and 4 Kg K for milk production, LW gain and calf production, the remainder returned to the system through excretions. Hence, more than 90% of the N and K, and approximately 81% of the P consumed by the animals were recycled to the system through the excretions. These results agree with those reported by Jarvis (1993) and Cadish et al (1994). However, 40% of the excretions occurred in the shade buildings and milking parlours ant thus these nutrients did not recycle in the system. An important internal recycling mechanism, especially for nitrogen and potassium, is their remobilization by the rejected pasture to re-use them for the regrowth activity. This is of particular interest in CT-115 Bank, since stems of CT-115 plants left after grazing remobilize an important amount of these nutrients, guarantee a favourable pasture regrowth (Martinez 1996). The return of all the excretion to the grassland is recommended as well as increasing the area of legumes to attain a satisfactory balance of N, P and K in the system. Further studies must consider maintenance fertilization, nutrient losses due to leaching and denitrification, as well as variation of the stable OM in the soil and the influence of hydro physical properties in the recycling process. The "Recycling" software was effective to determine the balance of nutrients in the dairy farm. Cadish, G., Schunke, R.N & Giller, K.E. 1994. Nitrogen cycling in a pure grass pasture and a grass-legume mixture on a red latosol in Brazil. Tropical Grasslands 28:43. Crespo G. y Rodríguez, I. 2006. Contribución al conocimiento del reciclaje de los nutrientes en el sistema suelo-pasto-animal. Instituto de Ciencia Animal, Editorial EDICA, La Habana, Cuba, 94 pp. Hirata, M., Sugimoto, Y.G & Ueno, M.1991. Use of a mathematical model to evaluate the effects of dung from grazing animals on pasture production. J. Japan Grassld. Sci. 37:303.

Crespo, G.; Rodriguez, I.; Martinez, O.

2009-04-01

45

Knowledge Sharing and Collaboration in Volcanic Risk Mitigation at Galeras Volcano, Colombia: A Participative Workshop to Reduce Volcanic Risk  

NASA Astrophysics Data System (ADS)

Galeras has been in nearly constant activity during modern historic times (roughly the past 500 years). Approximately 10,000 people live within an area designated as the highest-hazard and nearly 400,000 people are within areas of potential harmful effects. A wide variety of stakeholders are affected by the hazards, including: farmers, indigenous villagers, and people in urban environments. Hazards assessment and volcano monitoring are the responsibility of the Colombian Geological Survey (INGEOMINAS), whereas decisions regarding mitigation and response procedures are the responsibility of various governmental offices and the national emergency system (SNPAD). According to the current plan, when the risk level rises to a high level the people in the highest risk zone are required to evacuate. The volcano currently is in a very active, but fluctuating, condition and a future large eruption in a medium time frame (years to decades) is possible. There is a growing level of discomfort among many of the affected groups, including indigenous communities, farmers, and urban dwellers, related to the risk assessment. The general opinion prior to July 2009 was quite polarized as the decision makers saw the people of the region as poorly prepared to understand this hazard, whereas the population felt that their views were not being heard. The result was that the people in the hazardous areas decided not to evacuate, even during the current period of explosive activity. To resolve this situation the University of Nariño (Colombia) and the State University of New York at Buffalo organized a workshop named "Knowledge, Sharing and Collaboration in Volcanic Risk Mitigation at Galeras Volcano, Colombia" that was held in Pasto (Colombia), between 6 and 11 July, 2009. The general objective of this workshop was to analyze the existing hazard maps and safety plans for Galeras and form a bridge connecting scientists, decision makers, and other stake holders to promote a better understanding of the hazards presented by Galeras and the measures needed for mutual understanding and protection of people and property in the potentially threatened areas. Progress towards developing trust was achieved by requiring all the parties, including technicians, scientists, administrators and even farmers and indigenous people to listen to each others’ perceptions thought the entire week of the workshop. On the final day of the meeting a roundtable dialogue between the conflicting parts was moderated by social scientists. This intercourse identified, in a consensual manner, points of agreement to serve as starting positions for finding solutions to the areas of conflict. Irresolvable points were also identified during this roundtable discussion. The workshop showed that by sharing information within the framework of a full and frank communication, accepting (or at least listening to) each others’ arguments and trying to understand different points of view and served as a framework for an ongoing process of dialogue focused on resolving conflicts between the various stakeholder groups, even though they had previously reached the point of radicalized positions and statements.

Sheridan, M. F.; Cordoba, G. A.

2009-12-01

46

The Temporal Record of Ignimbrite Flare-ups - Filtered Signals From Deep  

NASA Astrophysics Data System (ADS)

Large silicic volcanic fields (10,000's of km<2>; 1000s- 10,000's of km<3>) are constructed during ignimbrite "flareups": intense periods of volcanism dominated by eruptions of ignimbrites with volumes in excess of 1000 km3. Concordantly, it is being increasingly recognized that cordilleran batholiths are also constructed during these events. Given the strong spatial, geochemical and petrological, and geophysical kinship between silicic volcanic and plutonic rocks it is reasonable to believe that these ignimbrite flare-ups must be accompanied by significant (and more voluminous) plutonic activity at depth and that most long-lived and productive magmatic provinces generate co-genetic volcanic and plutonic rocks, with connections to deeper levels of the crust. Flare-ups thus account for a significant portion of what can be collectively termed "crustal magmatism" - mantle-powered but significantly crust-modified. While the resolution of the temporal record preserved in the plutonism maybe compromised by late stage processes during the waning of a magmatic system, the temporal record of the volcanism provides a higher resolution record of the crustal magmatism. This is explored through the temporal record of the Altiplano-Puna Volcanic Complex of the Central Andes. This record of the flare-up reveals three types of signals. The broadest and dominant signal is that of the flare-up itself, a transient pulse magmatism of the order of 10<7> years that punctuates a background or baseline level of activity. This represents the waxing and waning of the primary thermal "drive" which is the mantle power input. The second signal is system-wide episodicity that operates on a time scale roughly an order of magnitude faster. This is manifested by intense pulses of eruption that last from 10<5> to 10<6> years separated by periods of 2x10<6> years. This is the result of crustal filtering or modulation of the primary mantle signal. The third signal is recorded in individual volcanic systems. Close correspondence between the timing of activity at the three main long-lived caldera complexes, La Pacana, Guacha, and Pastos Grandes is evidenced by major eruptions at 5.5 ± 0.15 Ma, 3.4 ± 0.5 Ma and 1.5 ± 0.2 Ma from each of these. This connotes a systemic "drive" for volcanic activity in these three systems. However, the magmatic systems of each of these centers is unique and any connection must be at depth and is not recorded materially in the erupted products, only temporally. Broad concordance of time scales of operation of the individual caldera systems and system-wide episodicity suggests that the main control on the timing of magmatism and volcanism is crustal modulation. The geophysically imaged low-seismic velocity zone, the Altiplano-Puna Magma Body, at 17 to 20 km, is the most likely modulator where thermal and chemical signals from the mantle/lower crust MASH zone are buffered and eventually translated to pre-eruptive upper crustal magma chambers.

de Silva, S. L.

2011-12-01

47

Ground-water in the Teresina-Campo Maior area, Piaui, Brazil  

USGS Publications Warehouse

The Teresina-Campo Maior area lies in a presently developing farming and grazing region near the margin of drought-prone northeast Brazil where irrigated farming offers the best potential for economic development. The area comprises 9,700 square kilometers largely of catinga-covered tabular uplands which are drained by the perennial Rio Parnatba. The climate is hot and humid most of the year but with distinct wet and dry seasons. Temperature extremes range from 20?C to 39?C and the annum rainfall averages 1,200 millimeters. The area's ground-water reservoir is contained chiefly in sandstone aquifers of six westward-dipping sedimentary rock formations, all part of the Maranhao sedimentary basin. The youngest of these formations, namely the Piaut (Pennsylvarian), Poti (Mississippian), Longa (Upper Devonian), and Cabecas (Middle Devoniar), contain the principal aquifers. Precipitation is the primary source of recharge to these aquifers and is more than sufficient to replenish current withdrawals from wells. Underlying the principal aquifers are the untapped Pimenteiras and Serra Grande Formations (both Lower Devonian) which in areas adjacent to the report area are moderately good to excellent water producers. These aquifers are recharged principally by lateral inflow from the east. Water also occurs in the alluvial deposits (Quaternary) underlying the flood plain of the Rio Parnatba but recurrent and uncontrolled flooding at present (1966) precludes their development. Of little economic importance, because they lie above the zone of saturation, are the thin erosional remnants of the Pastos Bons (Upper Triassic), Matuca, and Pedra de Fogo (both Permian) Formations. There are in the report area about 200 drilled wells most of which are pumped with power-driven engines. The wells range from 40 to 500 meters deep but most do not exceed 150 meters, and practically all are completed open hole. Yields range from 500 liters per day for 6-inch-diameter domestic wells to 240,000 liters per hour for 10-inch high-capacity municipal wells. Although there are many more dug wells than drilled wells, dug wells account for less than 1 percent of the current (1966) draft. The current annual withdrawal from the principal aquifers is approximately 5 million cubic meters of which almost half is used for municipal supply and the rest for rural household and irrigation uses. Additional water for public supply is available from aquifers now being pumped, and larger yields probably could be obtained from rural wells designed to take full advantage of the aquifer. Analyses of 28 samples show that the chemical quality of the water is well below the accepted limits of mineral concentration for most uses. Water from the Longa Formation averages 842 milligrams per liter in total dissolved solids and is more mineralized than that in the Piaul and Port Formations which contain water averaging less than 300 milligrams per liter. The water in the Piaui and Poti aquifers is the most suitable in the area for irrigation and has SAR values of C1-S1 and C2-S1. The quantities of water currently being used for irrigation are relatively small (600,000 cubic meters annually) but will increase substantially when intensive irrigation becomes a reality. Divisio de Hydrogeologia da Superintendancia do Desenvolvimento do Nordeste estimates that about 2,500 million cubic meters of water per year would be needed to irrigate about 250,000 hectares in the Teresina-Campo Maior area (about 25 percent of the total area). This goal, however, is not likely to be realized as the water requirement is five times the estimated natural recharge to the aquifers of the area. Most of the water-bearing formations in the report area have barely been tapped and can be developed a great deal more. In fact, the current annual withdrawal from the principal aquifers is less than 0.0025 percent of a conservative estimate of annual replenishment from rainfall. Additionally, only the

Rodis, Harry G.; Suszczynski, Edison F.

1972-01-01