Spinor: Visible and Infrared Spectro-Polarimetry at the National Solar Observatory     

Hector Socas-Navarro  David Elmore  Anna Pietarila  Anthony Darnell  Bruce W. Lites  Steven Tomczyk  Steven Hegwer 《Solar physics》2006,235(1-2):55-73

The Spectro-Polarimeter for Infrared and Optical Regions (SPINOR) is a new spectro-polarimeter that will serve as a facility instrument for the Dunn Solar Telescope at the National Solar Observatory. This instrument is capable of achromatic polarimetry over a very broad range of wavelengths, from 430 to 1600 nm, allowing for the simultaneous observation of several visible and infrared spectral regions with full Stokes polarimetry. Another key feature of the design is its flexibility to observe virtually any combination of spectral lines, limited only by practical considerations (e.g., the number of detectors available, space on the optical bench, etc.). Visiting Astronomers, National Solar Observatory, operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation.  相似文献   

Genetic identification of hake and megrim eggs in formaldehyde-fixed plankton samples   总被引：4，自引：0，他引：4  

Perez  Juliana; Alvarez  Paula; Martinez  Jose L.; Garcia-Vazquez  Eva 《ICES Journal of Marine Science》2005,62(5):908-914

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Large-scale environmental influences on the benthic macroinfauna of the southern Gulf of Mexico     

Hector A. Hernndez-Arana  Ashley A. Rowden  Martin J. Attrill  Richard M. Warwick  Gerardo Gold-Bouchot 《Estuarine, Coastal and Shelf Science》2003,58(4):825-841

The influence of large-scale natural disturbance from winter storms (‘northers’) and river runoff on the macrobenthic community structure of the southern Gulf of Mexico was investigated in both carbonate and transitional carbonate–terrigenous sedimentary environments. Samples of the infauna were obtained in three seasons from 13 stations from two 250 km transects along 80–170 and 20–50 m water depth. Samples after the northers season had the lowest total number of families and individuals, 114 and 2940, respectively, compared to the dry and rainy seasons with 129 and 132 families and 11580 and 15266 individuals, respectively. Spatial patterns of macroinfauna composition varied across and along the shelf as a response to sedimentary environments and depth. Coarser sediments from the carbonate area harboured the highest mean densities per station with 500–24,000 individuals m⁻² and 108–122 families in total, compared to the transitional sediment with 500–8200 individuals m⁻² and 56–74 families across the three seasons. Univariate and multivariate statistical techniques demonstrated that low densities and number of taxa were associated with winter storms, but storm influence was dependent on depth and sediment type. Multiple linear regression analysis and BIOENV analysis indicated that sediment mean grain size, percentage of clay and organic matter best explained the macroinfauna spatial patterns, although BIOENV indicated that depth has an overriding role. An increase in densities of opportunistic taxa (numerous polychaetes of small sizes) was observed four months after the ‘northers’ and this was more evident in the area of carbonate sediment. Additionally a combined disturbance from northers and river runoff is suspected to be responsible for a naturally impoverished macroinfauna community in the transitional sedimentary environment.  相似文献   

A powder diffraction quantification method (ALJOR) for atmospheric particulate matter     

M. Jordán  C. Alvarez  T. Sanfeliu 《Environmental Geology》2002,42(7):810-816

The percentage calculation of crystalline phases in atmospheric particulate matter samples by means of an adiabatic approach of the matrix-flushing method with preferred preparations that avoids preferential orientations, should never be interpreted as absolute values. On the contrary, it should be seen as an indicator of the significant differences between each and every analyzed sample. Factors such as the application of constants, which are only useful for preparations of polycrystalline samples free of preferential orientation, and/or like the deficient resolution shown by the diffraction diagrams for certain phyllosilicate phases, bring a high degree of uncertainty to these percentage calculations. An alternative method of crystalline and amorphous phase quantification is presented below. Once the majority phases in the samples were identified, appropriate pure phases corresponding to each of them were selected. Then, the corresponding calibration curves were built using corundum (number 676 NIST) as a reference pattern phase. After validating the obtained calibration curves, the constants corresponding to each phase and selected spacing were calculated. The ALJOR method has been used for the quantification of five samples.  相似文献   

A Comparison of Benzene and Toluene Plume Lengths for Sites Contaminated with Regular vs. Ethanol-Amended Gasoline   总被引：3，自引：0，他引：3  

G.M.L Ruiz-Aguilar  K. O'Reilly  P.J.J. Alvarez 《Ground Water Monitoring & Remediation》2003,23(1):48-53

This article describes various statistical analyses of plume-length data to evaluate the hypothesis that the presence of ethanol in gasoline may hinder the natural attenuation of hydrocarbon releases. Plume dimensions were determined for gasoline-contaminated sites to evaluate the effect of ethanol on benzene and toluene plume lengths. Data from 217 sites in Iowa (without ethanol; set 1) were compared to data from 29 sites in Kansas that were contaminated by ethanol-amended gasoline (10% ethanol by volume; set 2). The data were log-normally distributed, with mean benzene plume lengths (± standard deviation) of 193 ± 135 feet for set 1 and 263 ± 103 feet for set 2 (36% longer). The median lengths were 156 feet and 263 feet (69% longer), respectively. Mean toluene plume lengths were 185± 131 feet for set 1 and 211 ±99 feet for set 2 (14% longer), and the median lengths were 158 feet and 219 feet (39% longer), respectively. Thus, ethanol-containing BTEX plumes were significantly longer for benzene (p < 0.05), but not for toluene. A Wilcoxon signed rank test showed that toluene plumes were generally shorter than benzene plumes, which suggests that toluene was attenuated to a greater extent than benzene. This trend was more pronounced for set 2 (with ethanol), which may reflect that benzene attenuation is more sensitive to the depletion of electron acceptors caused by ethanol degradation. These results support the hypothesis that the presence of ethanol in gasoline can lead to longer benzene plumes. The importance of this effect, however, is probably site-specific, largely depending on the release scenario and the available electron acceptor pool.  相似文献   

Age and tectonostratigraphic significance of the Upper Carboniferous series in the basement of the Andean Frontal Cordillera: Geodynamic implications     

P. Busquets  F. Colombo  N. Heredia  N. Sole de Porta  L.R. Rodriguez Fernandez  J. Alvarez Marron   《Tectonophysics》2005,399(1-4):181

The age and tectonosedimentary environment of the Palaeozoic sediments on the Frontal Cordillera is not well known and earlier studies have been unable to satisfactorily explain the geological history of the basement of the Andes.In the vicinity of the old Castaño Viejo mine crop out various levels of partially metamorphosed microbialite limestones, which alternate with thin marly–lutitic interstrata. These levels contain abundant palynomorph remains, which allow the series to be dated as Silurian–Devonian. These data, together with the presence of warm climate fossils, lend support to the hypothesis of a major allochtony of the Chilenia Terrane (of which the Frontal Cordillera formed part), relative to the Cuyania Terrane (which included the Precordillera), prior to their amalgamation.Upper Carboniferous palynomorphs found during this study occur in association with resedimented palynomorphs and chitinozoa, of possible Devonian age. This demonstrates the equivalence of both fossiliferous series and their location within the upper part of the Upper Carboniferous Agua Negra Fm. The Silurian–Devonian elements, deformed during a phase prior to the Gondwanic orogeny, were eroded and transported to the foreland basin during the Upper Carboniferous.The palynomorph associations found in all samples correspond to the Ancistrospora palynological zone and to the Raistrickia densa–Convolutispora muriornata Biozone, which are indicative of Upper Carboniferous times. Characteristic forms such as Ancistrospora verrucosa and C. muriornata, both indicative of an Upper Carboniferous age, were found in samples from the Castaño Viejo area.Earlier interpretations of the Frontal Cordillera attributing the sedimentation to a palaeo-latitude at some distance from Gondwana, were based on the presence of Silurian–Devonian hot water stromatolithic limestones. Our results suggest that Cuyania and Chilenia were not necessarily separated by a great distance before their amalgamation. This in turn means that a large ocean was not necessarily consumed in the process.  相似文献   

Influence of the Madden Julian Oscillation on precipitation and surface air temperature in South America     

Mariano S. Alvarez  C. S. Vera  G. N. Kiladis  B. Liebmann 《Climate Dynamics》2016,46(1-2):245-262

The regional influence of the Madden–Julian oscillation (MJO) on South America is described. Maps of probability of weekly-averaged rainfall exceeding the upper tercile were computed for all seasons and related statistically with the phase of the MJO as characterized by the Wheeler–Hendon real-time multivariate MJO (RMM) index and with the OLR MJO Index. The accompanying surface air temperature and circulation anomalies were also calculated. The influence of the MJO on regional scales along with their marked seasonal variations was documented. During December–February when the South American monsoon system is active, chances of enhanced rainfall are observed in southeastern South America (SESA) region mainly during RMM phases 3 and 4, accompanied by cold anomalies in the extratropics, while enhanced rainfall in the South Atlantic Convergence Zone (SACZ) region is observed in phases 8 and 1. The SESA (SACZ) signal is characterized by upper-level convergence (divergence) over tropical South America and a cyclonic (anticyclonic) anomaly near the southern tip of the continent. Impacts during March–May are similar, but attenuated in the extratropics. Conversely, in June–November, reduced rainfall and cold anomalies are observed near the coast of the SACZ region during phases 4 and 5, favored by upper-level convergence over tropical South America and an anticyclonic anomaly over southern South America. In September–November, enhanced rainfall and upper-level divergence are observed in the SACZ region during phases 7 and 8. These signals are generated primarily through the propagation of Rossby wave energy generated in the region of anomalous heating associated with the MJO.  相似文献   

GDP and employment effects of policies to close the 2020 emissions gap     

Terry Barker  Eva Alexandri  Jean-Francois Mercure  Yuki Ogawa  Hector Pollitt 《Climate Policy》2016,16(4):393-414

Four policies might close the gap between the global GHG emissions expected for 2020 on the basis of current (2013) policies and the reduced emissions that will be needed if the long-term global temperature increase can be kept below the 2 °C internationally agreed limit. The four policies are (1) specific energy efficiency measures, (2) closure of the least-efficient coal-fired power plants, (3) minimizing methane emissions from upstream oil and gas production, and (4) accelerating the (partial) phase-out of subsidies to fossil-fuel consumption. In this article we test the hypothesis of the International Energy Agency (IEA) that these policies will not result in a loss of gross domestic product (GDP) and we estimate their employment effects using the E3MG global macro-econometric model. Using a set of scenarios we assess each policy individually and then consider the outcomes if all four policies were implemented simultaneously. We find that the policies are insufficient to close the emissions gap, with an overall emission reduction that is 30% less than that found by the IEA. World GDP is 0.5% higher in 2020, with about 6 million net jobs created by 2020 and unemployment reduced.

Policy relevance

The gap between GHG emissions expected under the Copenhagen and Cancun Agreements and that needed for emissions trajectories to have a reasonable chance of reaching the 2 °C target requires additional policies if it is to be closed. This article uses a global simulation model E3MG to analyse a set of policies proposed by the IEA to close the gap and assesses their macroeconomic effects as well as their feasibility in closing the gap. It complements the IEA assessment by estimating the GDP and employment implications separately by the different policies year by year to 2020, by major industries, and by 21 world regions.  相似文献   

Determinants of household flood evacuation mode choice in a developing country     

Hector R. Lim  Ma. Bernadeth B. Lim  Mongkut Piantanakulchai 《Natural Hazards》2016,82(1):507-530

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Snowmelt contribution to the sustainability of the irrigated Mendoza’s Oasis,Argentina: an isotope study     

Hector Massone  Daniel Martinez  Alberto Vich  Mauricio Quiroz Londoño  Darío Trombotto  Sebastián Grondona 《Environmental Earth Sciences》2016,75(6):520

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