bluuebunny/crossref_metadata_2025 huggingface dataset:
Conjunto residencial Niquia. Bogotá. Colombia
Authors: Lorenzo Castro Jaramillo Arquitecto
Published: September 2016

Lo singular de esta comunidad de 13 casas, es la respuesta arquitectónica que busca preservar, proteger, completar y aumentar el patrimonio ambiental de los cerros de Suba para la ciudad de Bogotá, así como, conservar e integrar la casa (1967) y el refugio (1963) del arquitecto Dicken Castro (Medellín, Colombia. 1922). El cuidado consciente de la vegetación del bosque alto andino, la siembra de especies nativas, el tratamiento integrado de la arquitectura y el agua, permiten no solo una mayor biodiversidad sino también una apuesta paisajística que se aleja del jardín convencional. Se renuncia a tener los garajes con acceso directo a las casas para dar paso a senderos peatonales.
Edificio San Martín Bogotá. Colombia
Authors: Fischer + Weiss Arquitectos , Arquitectos Cortés
Published: September 2016

Este edificio está basado en el concepto de que la arquitectura habla de sí misma y no de cargas simbólicas exógenas, las cuales -la historia lo ha demostrado- terminan perdiéndose.
Correlación entre las propiedades macro, micro y nanomecánicas en polímeros termoplásticos biodegradables
Authors: Arrieta Marina Patricia , Ferrándiz Santiago , López Martínez Juan , Rayón Encinas Emilio
Published: September 2016

En el presente trabajo se presenta el estudio de las propiedades mecánicas de un polímero biodegradable, poli(ácido láctico) (PLA), y sus variaciones debido a la adición de un 25 wt% de otro polímero biodegradable, poli(hidroxibutirato) (PHB). La muestra de PLA y la mezcla de PLA-PHB (75:25) fueron caracterizadas mecánicamente mediante ensayos de tracción, microdureza y nanoindentación con la finalidad de proporcionar un enfoque global de las propiedades mecánicas de estos materiales para facilitar a los estudiantes la comprensión de las propiedades mecánicas de los polímeros biodegradables.
Diseño físico-matemático de un espectrómetro óptico
Authors: Ferrando Martín Vicente , Remón Martín Laura , Furlan Walter D. , Monsoriu Serra Juan A.
Published: September 2016

En este trabajo se presenta el diseño y la construcción de un espectrómetro realizado en el laboratorio y el desarrollo de los modelos matemáticos necesarios para procesar y analizar el espectro adquirido con el mismo. Para la modelización de las funciones se ha utilizado el programa LabVIEW. El objetivo es acercar este tipo de instrumentación a los estudiantes de Ingeniería, tanto desde el punto de vista físico como matemático. La aplicación desarrollada ha sido integrada en la asignatura Sensores Físicos del Máster Universitario en Sensores Para Aplicaciones Industriales de la Universitat Politècnica de València. A modo de ejemplo, se han caracterizado diferentes fuentes de iluminación que emiten en distintas regiones del espectro electromagnético.
Saharan dust long-range transport across the Atlantic studied by an airborne
Doppler wind lidar and the MACC model
Authors: Chouza Fernando , Reitebuch Oliver , Benedetti Angela , Weinzierl Bernadett
Published: September 2016

Abstract. A huge amount of dust is transported every year from north Africa into the Caribbean region. This paper presents an investigation of this long-range transport process based on airborne Doppler wind lidar (DWL) measurements conducted during the SALTRACE campaign (June–July 2013), as well as an evaluation of the ability of the MACC (Monitoring Atmospheric Composition and Climate) global aerosol model to reproduce it and its associated features. Although both the modeled winds from MACC and the measurements from the DWL show a generally good agreement, some differences, particularly in the African easterly jet (AEJ) intensity, were noted. The observed differences between modeled and measured wind jet speeds are between 5 and 10 m s−1. The vertical aerosol distribution within the Saharan dust plume and the marine boundary layer is investigated during the June–July 2013 period based on the MACC aerosol model results and the CALIOP satellite lidar measurements. While the modeled Saharan dust plume extent shows a good agreement with the measurements, a systematic underestimation of the marine boundary layer extinction is observed. Additionally, three selected case studies covering different aspects of the Saharan dust long-range transport along the west African coast, over the North Atlantic Ocean and the Caribbean are presented. For the first time, DWL measurements are used to investigate the Saharan dust long-range transport. Simultaneous wind and backscatter measurements from the DWL are used, in combination with the MACC model, to analyze different features associated with the long-range transport, including an African easterly wave trough, the AEJ and the intertropical convergence zone.
The influence of temperature on ozone production under varying NOx conditions – a modelling study
Authors: Coates Jane , Mar Kathleen A. , Ojha Narendra , Butler Tim M.
Published: September 2016

Abstract. Surface ozone is a secondary air pollutant produced during the atmospheric photochemical degradation of emitted volatile organic compounds (VOCs) in the presence of sunlight and nitrogen oxides (NOx). Temperature directly influences ozone production through speeding up the rates of chemical reactions and increasing the emissions of VOCs, such as isoprene, from vegetation. In this study, we used an idealised box model with different chemical mechanisms (Master Chemical Mechanism, MCMv3.2; Common Representative Intermediates, CRIv2; Model for OZone and Related Chemical Tracers, MOZART-4; Regional Acid Deposition Model, RADM2; Carbon Bond Mechanism, CB05) to examine the non-linear relationship between ozone, NOx and temperature, and we compared this to previous observational studies. Under high-NOx conditions, an increase in ozone from 20 to 40 °C of up to 20 ppbv was due to faster reaction rates, while increased isoprene emissions added up to a further 11 ppbv of ozone. The largest inter-mechanism differences were obtained at high temperatures and high-NOx emissions. CB05 and RADM2 simulated more NOx-sensitive chemistry than MCMv3.2, CRIv2 and MOZART-4, which could lead to different mitigation strategies being proposed depending on the chemical mechanism. The increased oxidation rate of emitted VOC with temperature controlled the rate of Ox production; the net influence of peroxy nitrates increased net Ox production per molecule of emitted VOC oxidised. The rate of increase in ozone mixing ratios with temperature from our box model simulations was about half the rate of increase in ozone with temperature observed over central Europe or simulated by a regional chemistry transport model. Modifying the box model set-up to approximate stagnant meteorological conditions increased the rate of increase of ozone with temperature as the accumulation of oxidants enhanced ozone production through the increased production of peroxy radicals from the secondary degradation of emitted VOCs. The box model simulations approximating stagnant conditions and the maximal ozone production chemical regime reproduced the 2 ppbv increase in ozone per degree Celsius from the observational and regional model data over central Europe. The simulated ozone–temperature relationship was more sensitive to mixing than the choice of chemical mechanism. Our analysis suggests that reductions in NOx emissions would be required to offset the additional ozone production due to an increase in temperature in the future.
Source apportionment of atmospheric ammonia before, during, and after the
2014 APEC summit in Beijing using stable nitrogen isotope signatures
Authors: Chang Yunhua , Liu Xuejun , Deng Congrui , Dore Anthony J. , Zhuang Guoshun
Published: September 2016

Abstract. Stable nitrogen isotope composition (δ15N) offers new opportunities to address the long-standing and ongoing controversy regarding the origins of ambient ammonia (NH3), a vital precursor of PM2.5 (particulate matters with aerodynamic diameter equal or less than 2.5 µm) inorganic components, in the urban atmosphere. In this study, the δ15N values of NH3 samples collected from various sources were constrained using a novel and robust chemical method coupled with standard elemental analysis procedures. Independent of the wide variation in mass concentrations (ranging from 33 (vehicle) to over 6000 (human excreta) µg m−3), different NH3 sources have generally different δ15N values (ranging from −52.0 to −9.6 ‰). Significantly high δ15N values are seen as a characteristic feature of all vehicle-derived NH3 samples (−14.2 ± 2.8 ‰), which can be distinguished from other sources emitted at environmental temperature (−29.1 ± 1.7, −37.8 ± 3.6, and −50.0 ± 1.8 ‰ for livestock, waste, and fertilizer, respectively). The isotope δ15N signatures for a range of NH3 emission sources were used to evaluate the contributions of the different sources within measured ambient NH3 in Beijing, using an isotope mixing model (IsoSource). The method was used to quantify the sources of ambient NH3 before, during and after the 2014 Asia-Pacific Economic Cooperation (APEC) summit, when a set of stringent air quality control measures were implemented. Results show that the average NH3 concentrations (the overall contributions of traffic, waste, livestock, and fertilizer) during the three periods were 9.1 (20.3, 28.3, 23.6, and 27.7 %), 7.3 (8.8, 24.9, 14.3, and 52.0 %), and 12.7 (29.4, 23.6, 31.7, and 15.4 %) µg m−3, respectively, representing a 20.0 % decrease first and then a 74.5 % increase in overall NH3 mass concentrations. During (after) the summit, the contributions of traffic, waste, livestock, and fertilizer decreased (increased) by 56.7 (234.2), 12.0 (−5.0), 39.4 (120.8), and −87.7 % (−70.5 %) when compared with periods before (during) the summit, respectively, signifying that future NH3 control efforts in megacities like Beijing should prioritize traffic sector as well as livestock breeding. The results show that isotope ratio measurements of NH3 to be a valuable tool to quantify the atmospheric sources of NH3 in urban atmospheres.
Validation of brightness and physical temperature from two scanning
microwave radiometers in the 60 GHz O2 band using radiosonde measurements
Authors: Navas-Guzmán Francisco , Kämpfer Niklaus , Haefele Alexander
Published: September 2016

Abstract. In this paper, we address the assessment of the tropospheric performance of a new temperature radiometer (TEMPERA) at 60 GHz. With this goal, an intercomparison campaign was carried out at the aerological station of MeteoSwiss in Payerne (Switzerland). The brightness temperature and the tropospheric temperature were assessed by means of a comparison with simultaneous and collocated radiosondes that are launched twice a day at this station. In addition, the TEMPERA performances are compared with the ones from a commercial microwave radiometer (HATPRO), which has some different instrumental characteristics and uses a different inversion algorithm. Brightness temperatures from both radiometers were compared with the ones simulated using a radiative transfer model and atmospheric profiles from radiosondes. A total of 532 cases were analyzed under all weather conditions and evidenced larger brightness temperature deviations between the two radiometers and the radiosondes for the most transparent channels. Two different retrievals for the TEMPERA radiometer were implemented in order to evaluate the effect of the different channels on the temperature retrievals. The comparison with radiosondes evidenced better results very similar to the ones from HATPRO, when the eight more opaque channels were used. The study shows the good performance of TEMPERA to retrieve temperature profiles in the troposphere. The inversion method of TEMPERA is based on the optimal estimation method. The main advantage of this algorithm is that there is no necessity for radiosonde information to achieve good results in contrast to conventional methods as neural networks or lineal regression. Finally, an assessment of the effect of instrumental characteristics as the filter response and the antenna pattern on the brightness temperature showed that they can have an important impact on the most transparent channels.
A laser-induced fluorescence instrument for aircraft measurements of sulfur
dioxide in the upper troposphere and lower stratosphere
Authors: Rollins Andrew W. , Thornberry Troy D. , Ciciora Steven J. , McLaughlin Richard J. , Watts Laurel A. , Hanisco Thomas F. , Baumann Esther , Giorgetta Fabrizio R. , Bui Thaopaul V. , Fahey David W. , Gao Ru-Shan
Published: September 2016

Abstract. This work describes the development and testing of a new instrument for in situ measurements of sulfur dioxide (SO2) on airborne platforms in the upper troposphere and lower stratosphere (UT–LS). The instrument is based on the laser-induced fluorescence technique and uses the fifth harmonic of a tunable fiber-amplified semiconductor diode laser system at 1084.5 nm to excite SO2 at 216.9 nm. Sensitivity and background checks are achieved in flight by additions of SO2 calibration gas and zero air, respectively. Aircraft demonstration was performed during the NASA Volcano-Plume Investigation Readiness and Gas-Phase and Aerosol Sulfur (VIRGAS) experiment, which was a series of flights using the NASA WB-57F during October 2015 based at Ellington Field and Harlingen, Texas. During these flights, the instrument successfully measured SO2 in the UT–LS at background (non-volcanic) conditions with a precision of 2 ppt at 10 s and an overall uncertainty determined primarily by instrument drifts of ±(16 % + 0.9 ppt).
Potential of a geostationary geoCARB mission to estimate surface emissions of
CO2, CH4 and CO in a polluted urban environment: case
study Shanghai
Authors: O'Brien Denis M. , Polonsky Igor N. , Utembe Steven R. , Rayner Peter J.
Published: September 2016

Abstract. This paper describes a numerical experiment to test the ability of the proposed geoCARB satellite to estimate emissions of trace gases (CO2, CH4 and CO) in the polluted urban environment of Shanghai. The meteorology over Shanghai is simulated with the Weather Research and Forecasting (WRF) model for a 9-day period in August 2010. The meteorology includes water and ice clouds. The chemistry version of WRF (WRF-Chem V3.6.1) is used to predict the chemical composition, mass density and number density of aerosol species. Spectra in the bands measured by geoCARB are calculated, including the effects of polarisation and multiple scattering of radiation by clouds, aerosols and molecules. Instrument noise is added, and column-averaged trace-gas mole fractions are estimated from the noisy spectra using an algorithm based on that for the Greenhouse Gases Observing Satellite (GOSAT) and the Orbiting Carbon Observatory-2 (OCO-2) but adapted to geoCARB. As expected, the high aerosol loadings are challenging. However, when the retrieval algorithm is provided with regionally adjusted aerosol optical properties, as might be determined from observations of dark targets within the field of regard, the accuracies of retrieved concentrations are comparable to those reported earlier for geoCARB. Statistics of the errors in the retrieved column-averaged concentrations are used to predict the reduction in uncertainty of surface emissions possible with remotely sensed data.
Optimization of GPS water vapor tomography technique with radiosonde and
COSMIC historical data
Authors: Ye Shirong , Xia Pengfei , Cai Changsheng
Published: September 2016

Abstract. The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in numerical weather prediction. GPS tomography technique has been proved effectively for three-dimensional water vapor reconstruction. In this study, the tomography processing is optimized in a few aspects by the aid of radiosonde and COSMIC historical data. Firstly, regional tropospheric zenith hydrostatic delay (ZHD) models are improved and thus the zenith wet delay (ZWD) can be obtained at a higher accuracy. Secondly, the regional conversion factor of converting the ZWD to the precipitable water vapor (PWV) is refined. Next, we develop a new method for dividing the tomography grid with an uneven voxel height and a varied water vapor layer top. Finally, we propose a Gaussian exponential vertical interpolation method which can better reflect the vertical variation characteristic of water vapor. GPS datasets collected in Hong Kong in February 2014 are employed to evaluate the optimized tomographic method by contrast with the conventional method. The radiosonde-derived and COSMIC-derived water vapor densities are utilized as references to evaluate the tomographic results. Using radiosonde products as references, the test results obtained from our optimized method indicate that the water vapor density accuracy is improved by 15 and 12 % compared to those derived from the conventional method below the height of 3.75 km and above the height of 3.75 km, respectively. Using the COSMIC products as references, the results indicate that the water vapor density accuracy is improved by 15 and 19 % below 3.75 km and above 3.75 km, respectively.
Greenhouse gas emissions from fen soils used for forage production in
northern Germany
Authors: Poyda Arne , Reinsch Thorsten , Kluß Christof , Loges Ralf , Taube Friedhelm
Published: September 2016

Abstract. A large share of peatlands in northwestern Germany is drained for agricultural purposes, thereby emitting high amounts of greenhouse gases (GHGs). In order to quantify the climatic impact of fen soils in dairy farming systems of northern Germany, GHG exchange and forage yield were determined on four experimental sites which differed in terms of management and drainage intensity: (a) rewetted and unutilized grassland (UG), (b) intensive and wet grassland (GW), (c) intensive and moist grassland (GM) and (d) arable forage cropping (AR). Net ecosystem exchange (NEE) of CO2 and fluxes of CH4 and N2O were measured using closed manual chambers. CH4 fluxes were significantly affected by groundwater level (GWL) and soil temperature, whereas N2O fluxes showed a significant relation to the amount of nitrate in top soil. Annual balances of all three gases, as well as the global warming potential (GWP), were significantly correlated to mean annual GWL. A 2-year mean GWP, combined from CO2–C eq. of NEE, CH4 and N2O emissions, as well as C input (slurry) and C output (harvest), was 3.8, 11.7, 17.7 and 17.3 Mg CO2–C eq. ha−1 a−1 for sites UG, GW, GM and AR, respectively (standard error (SE) 2.8, 1.2, 1.8, 2.6). Yield-related emissions for the three agricultural sites were 201, 248 and 269 kg CO2–C eq. (GJ net energy lactation; NEL)−1 for sites GW, GM and AR, respectively (SE 17, 9, 19). The carbon footprint of agricultural commodities grown on fen soils depended on long-term drainage intensity rather than type of management, but management and climate strongly influenced interannual on-site variability. However, arable forage production revealed a high uncertainty of yield and therefore was an unsuitable land use option. Lowest yield-related GHG emissions were achieved by a three-cut system of productive grassland swards in combination with a high GWL (long-term mean  ≤  20 cm below the surface).
Effect of cover crops on greenhouse gas emissions in an irrigated field
under integrated soil fertility management
Authors: Guardia Guillermo , Abalos Diego , García-Marco Sonia , Quemada Miguel , Alonso-Ayuso María , Cárdenas Laura M. , Dixon Elizabeth R. , Vallejo Antonio
Published: September 2016

Abstract. Agronomical and environmental benefits are associated with replacing winter fallow by cover crops (CCs). Yet, the effect of this practice on nitrous oxide (N2O) emissions remains poorly understood. In this context, a field experiment was carried out under Mediterranean conditions to evaluate the effect of replacing the traditional winter fallow (F) by vetch (Vicia sativa L.; V) or barley (Hordeum vulgare L.; B) on greenhouse gas (GHG) emissions during the intercrop and the maize (Zea mays L.) cropping period. The maize was fertilized following integrated soil fertility management (ISFM) criteria. Maize nitrogen (N) uptake, soil mineral N concentrations, soil temperature and moisture, dissolved organic carbon (DOC) and GHG fluxes were measured during the experiment. Our management (adjusted N synthetic rates due to ISFM) and pedo-climatic conditions resulted in low cumulative N2O emissions (0.57 to 0.75 kg N2O-N ha−1 yr−1), yield-scaled N2O emissions (3–6 g N2O-N kg aboveground N uptake−1) and N surplus (31 to 56 kg N ha−1) for all treatments. Although CCs increased N2O emissions during the intercrop period compared to F (1.6 and 2.6 times in B and V, respectively), the ISFM resulted in similar cumulative emissions for the CCs and F at the end of the maize cropping period. The higher C : N ratio of the B residue led to a greater proportion of N2O losses from the synthetic fertilizer in these plots when compared to V. No significant differences were observed in CH4 and CO2 fluxes at the end of the experiment. This study shows that the use of both legume and nonlegume CCs combined with ISFM could provide, in addition to the advantages reported in previous studies, an opportunity to maximize agronomic efficiency (lowering synthetic N requirements for the subsequent cash crop) without increasing cumulative or yield-scaled N2O losses.
A 414-year tree-ring-based April–July minimum temperature reconstruction and
its implications for the extreme climate events, northeast China
Authors: Lyu Shanna , Li Zongshan , Zhang Yuandong , Wang Xiaochun
Published: September 2016

Abstract. A ring-width series was used as a proxy to reconstruct the past 414-year record of April–July minimum temperature at Laobai Mountain, northeast China. The chronology was built using standard tree-ring procedures for providing comparable information in this area while preserving low-frequency signals. By analyzing the relationship between the tree-ring chronology of Korean pine (Pinus koraiensis) and meteorological data, we found that the standard chronology was significantly correlated with the April–July minimum temperature (r =  0.757, p < 0.01). Therefore, the April–July minimum temperature since 1600 (more than six trees, but the expressed population signal (EPS) is greater than 0.85 since 1660) was reconstructed by this tree-ring series. The reconstruction equation accounted for 57.3 % of temperature variation, and it was proved reliable by testing with several methods (e.g., sign test, product mean test, reduction of the error, and coefficient of efficiency). Reconstructed April–July minimum temperature on Laobai Mountain showed six major cold periods (1605–1616, 1645–1677, 1684–1691, 1911–1924, 1930–1942, and 1951–1969) and seven major warm periods (1767–1785, 1787–1793, 1795–1807, 1819–1826, 1838–1848, 1856–1873, and 1991–2008) during the past 414 years. The reconstructed low-temperature periods in the 17th and early 18th century were consistent with the Little Ice Age (LIA) in the Northern Hemisphere, and the rate of warming in the 19th century was significantly slower than that in the late 20th century. In addition, the reconstructed series was fairly consistent with the historical and natural disaster records of extreme climate events (e.g., cold damage and frost disaster) in this area. This temperature record provides new evidence of past climate variability, and can be used to predict the climate trend in the future in northeast China.
Global Gridded Crop Model evaluation: benchmarking, skills, deficiencies and implications
Authors: Müller Christoph , Elliott Joshua , Chryssanthacopoulos James , Arneth Almut , Balkovic Juraj , Ciais Philippe , Deryng Delphine , Folberth Christian , Glotter Michael , Hoek Steven , Iizumi Toshichika , Izaurralde Roberto C. , Jones Curtis , Khabarov Nikolay , Lawrence Peter , Liu Wenfeng , Olin Stefan , Pugh Thomas A. M. , Ray Deepak , Reddy Ashwan , Rosenzweig Cynthia , Ruane Alexander C. , Sakurai Gen , Schmid Erwin , Skalsky Rastislav , Song Carol X. , Wang Xuhui , de Wit Allard , Yang Hong
Published: September 2016

Abstract. Crop models are increasingly used to simulate crop yields at the global scale, but there so far is no general framework on how to assess model performance. We here evaluate the simulation results of 14 global gridded crop modeling groups that have contributed historic crop yield simulations for maize, wheat, rice and soybean to the Global Gridded Crop Model Intercomparison (GGCMI) of the Agricultural Model Intercomparison and Improvement Project (AgMIP). Simulation results are compared to reference data at global, national and grid cell scales and we evaluate model performance with respect to time series correlation, spatial correlation and mean bias. We find that GGCMs show mixed skill in reproducing time-series correlations or spatial patterns at the different spatial scales. Generally, maize, wheat and soybean simulations of many GGCMs are capable of reproducing larger parts of observed temporal variability (time series correlation coefficients (r) of up to 0.888 for maize, 0.673 for wheat and 0.643 for soybean at the global scale) but rice yield variability cannot be well reproduced by most models. Yield variability can be well reproduced for most major producer countries by many GGCMS and for all countries by at least some. A comparison with gridded yield data and a statistical analysis of the effects of weather variability on yield variability shows that the ensemble of GGCMs can explain more of the yield variability than an ensemble of regression models for maize and soybean, but not for wheat and rice. We identify future research needs in global gridded crop modeling and for all individual crop modeling groups. In the absence of a purely observation-based benchmark for model evaluation, we propose that the best performing crop model per crop and region establishes the benchmark for all others, and modelers are encouraged to investigate how crop model performance can be increased. We make our evaluation system accessible to all crop modelers so that also other modeling groups can test their model performance against the reference data and the GGCMI benchmark.
The Framework for 0-D Atmospheric Modeling (F0AM) v3.1
Authors: Wolfe Glenn M. , Marvin Margaret R. , Roberts Sandra J. , Travis Katherine R. , Liao Jin
Published: September 2016

Abstract. The Framework for 0-D Atmospheric Modeling (F0AM) is a flexible and user-friendly MATLAB-based platform for simulation of atmospheric chemistry systems. The F0AM interface incorporates front-end configuration of observational constraints and model setups, making it readily adaptable to simulation of photochemical chambers, Lagrangian plumes, and steady-state or time-evolving solar cycles. Six different chemical mechanisms and three options for calculation of photolysis frequencies are currently available. Example simulations are presented to illustrate model capabilities and, more generally, highlight some of the advantages and challenges of 0-D box modeling.
Snow cover dynamics in Andean watersheds of Chile (32.0–39.5° S)
during the years 2000–2013
Authors: Stehr Alejandra , Aguayo Mauricio
Published: September 2016

Abstract. Andean watersheds present important snowfall accumulation mainly during the winter which is later melted during spring and part of the summer. The effect of snowmelt on the water balance can be critical to sustain agriculture activities, hydropower generation, urban water supply and wildlife. In Chile 25 % of the territory between the Valparaiso and Araucanía Regions comprise areas where snow precipitation occurs. As in many other difficult-to-access regions of the world, in the Chilean Andes there is a lack of hydrological data like discharge, snow courses, snow depths, which complicate the analysis of important hydrological processes (e.g. water availability). Remote sensing provides a promising opportunity to enhance the assessment and monitoring of the spatial and temporal variability of snow characteristics, like Snow Cover Area (SCA) and Snow Cover Dynamic (SCD). In the above mentioned context the objectives of this study are to evaluate the suitability of MOD10A2 to estimate SCA and to assess SCD at five watersheds (Aconcagua, Rapel, Maule, Biobío and Toltén) located in the Chilean Andes, between latitude 32.0º S and 39.5º S. Those watershed were chosen because their importance in terms of number of inhabitants, and dependence of economic activities on water resources. SCA area was obtained from MOD10A2 for the period 2000–2013 and SCD was analysed through a number of statistical tests to explore observed trends. Prior of obtaining SCA for trend analysis, a validation of MOD10A2 product was done; comparing presence of snow predicted by MODIS with ground observations. Results indicate that there is an overall agreement from 81 to 98 % between SCA-determined from ground observations, and MOD10A2, showing that MODIS snow product can be taken as a feasible remote sensing tool for SCA estimation in South-Central Chile. Regarding SCD no significant reduction in SCA area for 2000–2013 was detected, with the exception of the Aconcagua and Rapel watersheds, although an important decline in SCA for the period of 2012 and 2013 was also evident, which is coincident with the rainfall deficit for the same years. Findings were compared against ENSO episodes occurring during 2010–2013, detecting that Niña years are coincident with maximum SCA during winter in all watersheds.
A comparison between parameter regionalization and model calibration with flow duration curves for prediction in ungauged catchments
Authors: Kim Daeha , Jung Ilwon , Chun Jong Ahn
Published: September 2016

Abstract. Streamflow prediction in ungauged catchments is essential for hydrological applications because most catchments in the world are ungauged. The flow duration curve (FDC) has received increasing attention as a criterion for calibration of runoff models in ungauged catchments; however, performance of the FDC-based model calibration was barely evaluated in comparison with parameter regionalization. In this study, we conducted a comparative assessment between the conventional proximity-based parameter regionalization and the model calibration with regional FDCs. Leave-one-out evaluations of the two methods showed that the proximity-based parameter regionalization outperformed the model calibration with regionalized FDCs in hydrograph prediction. No information of flow timing in FDCs seems to cause high uncertainty in flow predictions. The relative merits of the model calibration with regional FDCs were low bias in predicted flows and high reproducibility of the baseflow index. From the evaluation of flow signature reproducibility, it was indicated that the rising limb density is likely to be orthogonal to the FDCs, and thus additional conditioning with the rising limb density is expected to improve the model calibration with regional FDCs.
Wavelet analysis of the singular spectral reconstructed time series to study the imprints of solar–ENSO–geomagnetic activity on Indian climate
Authors: Sunkara Sri Lakshmi , Tiwari Rama Krishna
Published: September 2016

Abstract. To study the imprints of the solar–ENSO–geomagnetic activity on the Indian subcontinent, we have applied singular spectral analysis (SSA) and wavelet analysis to the tree-ring temperature variability record from the Western Himalayas. Other data used in the present study are the solar sunspot number (SSN), geomagnetic indices (aa index), and the Southern Oscillation Index (SOI) for the common time period of 1876–2000. Both SSA and wavelet spectral analyses reveal the presence of 5–7-year short-term ENSO variations and the 11-year solar cycle, indicating the possible combined influences of solar–geomagnetic activities and ENSO on the Indian temperature. Another prominent signal corresponding to 33-year periodicity in the tree-ring record suggests the Sun-temperature variability link probably induced by changes in the basic state of the Earth's atmosphere. In order to complement the above findings, we performed a wavelet analysis of SSA reconstructed time series, which agrees well with our earlier results and increases the signal-to-noise ratio, thereby showing the strong influence of solar–geomagnetic activity and ENSO throughout the entire period. The solar flares are considered responsible for causing the atmospheric circulation patterns. The net effect of solar–geomagnetic processes on the temperature record might suggest counteracting influences on shorter (about 5–6-year) and longer (about 11–12-year) timescales. The present analyses suggest that the influence of solar activities on the Indian temperature variability operates in part indirectly through coupling of ENSO on multilateral timescales. The analyses, hence, provide credible evidence of teleconnections of tropical Pacific climatic variability and Indian climate ranging from inter-annual to decadal timescales and also suggest the possible role of exogenic triggering in reorganizing the global Earth–ocean–atmospheric systems.
Observability of fine-scale ocean dynamics in the Northwest Mediterranean Sea
Authors: Morrow Rosemary , Carret Alice , Birol Florence , Nino Fernando , Valladeau Guillaume , Boy Francois , Bachelier Celine , Zakardjian Bruno
Published: September 2016

Abstract. Technological advances in the recent satellite altimeter missions of Jason-2, Saral/AltiKa and Cryosat-2 have improved their signal-to-noise, allowing us to observe finer-scale ocean processes with along-track data. Here, we analyse the noise levels and observable ocean scales in the northwest Mediterranean Sea, using spectral analyses of along-track sea surface height from the three missions. Jason-2 has a higher mean noise level with strong seasonal variations, with higher noise in winter due to the rougher sea-state. Saral/AltiKa has the lowest noise, again with strong seasonal variations. Cryosat-2 is in SAR mode in the Mediterranean Sea but with lower resolution ocean corrections; its statistical noise level is moderate with little seasonal variation. These noise levels impact on the ocean scales we can observe. In winter, when the mixed layers are deepest and the sub-mesoscale is energetic, all of the altimeter missions can observe wavelengths down to 40–50 km (individual feature diameters of 20–25 km). In summer when the sub-mesoscales are weaker, Saral can detect ocean scales down to 35 km wavelength, whereas the higher noise from Jason-2 and Cryosat-2 blocks the observation of scales less than 50–55 km wavelength. This statistical analysis is completed by individual case studies, where filtered along-track altimeter data are compared with collocated glider and HF radar data. The glider comparisons work well for larger ocean structures, but observation of the smaller, rapidly moving dynamics are difficult to collocate in space and time (gliders cover 200 km in a few days, altimetry in 30 secs). HF radar surface currents at Toulon measure the meandering Northern Current, and their good temporal sampling shows promising results in comparison to collocated Saral altimetric currents. Techniques to separate the geostrophic component from the wind-driven ageostrophic flow need further development in this coastal band.
The Achaeans and the Europeans: An Interdisciplinary Comparison of Federations
Authors: Economou Emmanouil M. L. , Kyriazis Nicholas C.
Published: September 2016

In the present essay we undertake the comparison of two federations, the ancient Greek Achaean with the European Union (EU). We present the institutional (political and economic) set up of the Achaean federation and then we proceed to a comparison between them under a specific set of criteria and discuss differences and similarities. We conclude offering some insights concerning democratisation and cohesion based on the institutional organization of the ancient Greek federation. We found that some of the basic Achaean federal institutions could be served as a benchmark for the further promotion of democratic procedures and social cohesion in economic terms in the European Union.
Level of Visual Acuity Necessary to Avoid False-Positives on the HRR and Ishihara Color Vision Tests
Authors: Ng Jason S. , Shih Brian
Published: September 2016

Purpose

Minimizing false-positives (FPs) when evaluating color vision is important in eye care. Identification of plate 1 (demonstration plate) is often considered a way to avoid FPs. However, few studies have quantified the minimum level of visual acuity (VA) that would minimize FPs for the Ishihara and HRR color tests.

Methods

Threshold levels of optical defocus were obtained from 25 color normal subjects. Blur levels were obtained for Ishihara (38 plate) plates 1, 10, and 15 and 4th edition HRR plates 1, 7, 10, and 20 using the method of limits. Corresponding VAs were measured through these blur levels at 40 centimeters after adjusting for the dioptric distance difference. Analysis of variance testing was used to analyze the data.

Results

Mean optical defocus values in diopters (mean ± SD) for HRR plates 1, 7, 10, and 20 were 6.23 ± 1.61, 1.23 ± 1.16, 2.41 ± 1.31, and 7.96 ± 2.03, respectively, and for Ishihara plates 1, 10, and 15 were 5.70 ± 1.52, 3.68 ± 1.71, and 4.62 ± 1.56, respectively. There was a significant difference between the screening and demonstration plates for both tests (p<0.001).

Conclusions

Based on the plate in each test that was found to be the least tolerant to blur, the average minimum VAs needed to identify the screening plates were approximately 20/180 for the Ishihara test and 20/50 for the HRR test. Identifying the demonstration plate in the Ishihara and HRR tests does not ensure FPs will be avoided.
Intraoperative Complications of Patients Undergoing Small-Gauge and 20-Gauge Vitrectomy: A Database Study of 4,274 Procedures
Authors: Neffendorf James E. , Gupta Bhaskar , Williamson Tom H.
Published: September 2016

Purpose

To compare the intraoperative complications between 23-G and 20-G instrumentation in patients undergoing pars plana vitrectomy (PPV).

Methods

This was a retrospective comparative study of 4,274 PPV procedures by the same surgical team between 1998 and 2016. A total of 2,648 operations were carried out with 20-G surgery and 1,626 operations with 23-G surgery. Main outcome measures were the incidence of choroidal haemorrhage, iatrogenic retinal break, and lens touch.

Results

The most frequent surgical indication in both 20-G and 23-G was rhegmatogenous retinal detachment (RRD), 38.7% (1,026/2,648) and 45.9% (746/1,626), respectively. The frequency of choroidal haemorrhage was 1.0% with 20-G surgery (26/2,648) vs 0.6% with 23-G (9/1,626, p = 0.16). Subgroup analysis showed the increased risk was present in RRD surgery, 1.6% (16/1,026) vs 0.1% (1/746, p = 0.002), but not in all other indications combined, 20-G with 0.6% (10/1,622) and 23-G 0.9% (8/88, p = 0.46). This increased risk was also true for RRD when excluding combined scleral buckle surgery. There was an increased risk of iatrogenic retinal break in RRD cases undergoing 20-G, 5.8% (60/1,026), compared to 23-G vitrectomy, 1.9% (14/746, p<0.0001). There was no difference in rates of lens touch between 20-G and 23-G.

Conclusions

23-G microincisional PPV has a lower risk of choroidal haemorrhage and iatrogenic retinal tears than 20-G vitrectomy particularly for eyes with RRD.
Reproducibility and Repeatability of Foveal Avascular Zone Area Measurements Using Swept-Source Optical Coherence Tomography Angiography in Healthy Subjects
Authors: Mastropasqua Rodolfo , Toto Lisa , Mattei Peter A. , Di Nicola Marta , Zecca Isaia A.L. , Carpineto Paolo , Di Antonio Luca
Published: September 2016

Purpose

To assess the reproducibility and repeatability of foveal avascular zone (FAZ) area measurements using swept-source optical coherence tomography angiography (SS-OCTA) in healthy subjects.

Methods

Sixty-four eyes of 64 healthy volunteers were randomly subjected to FAZ area measurements using SS-OCTA by 2 examiners in 2 different sessions.

Results

The FAZ areas measured by the first and second observer were 0.269 ± 0.092 mm2 and 0.270 ± 0.090 mm2, respectively. Within subjects, the coefficients of variations were 2.44% (95% confidence interval [CI] 1.95% to 2.93%) and 2.66% (95% CI 2.00% to 3.31%) for the first and second observers, respectively. The coefficient of repeatability average measurements of FAZ area were 0.021 mm2 and 0.024 mm2. The intraclass correlation coefficient values were 0.993 (95% CI 0.989 to 0.996) and 0.991 (95% CI 0.986 to 0.995). Interobserver and intraobserver concordance correlation coefficients ranged from 0.998 (95% CI 0.997 to 0.999) to 0.999 (95% CI 0.998 to 0.999) and from 0.989 (95% CI 0.982 to 0.993) to 0.987 (95% CI 0.979 to 0.992), respectively.

Conclusions

The FAZ area measurements by means of SS-OCTA showed high reproducibility and repeatability in healthy eyes.
Intravitreal Ranibizumab for Retinal Arterial Macroaneurysm: Long-Term Results of a Prospective Study
Authors: Chatziralli Irini , Maniatea Aggeliki , Koubouni Kyriakoula , Parikakis Efstratios , Mitropoulos Panagiotis
Published: September 2016

Purpose

To evaluate the potential efficacy and safety of primary intravitreal ranibizumab in patients with symptomatic retinal arterial macroaneurysm (RAM).

Methods

This prospective study comprised 5 eyes with RAM treated with intravitreal ranibizumab. At baseline, all patients underwent best-corrected visual acuity (BCVA) measurement, ophthalmic examination including slit-lamp biomicroscopy, and central foveal thickness (CFT) measurement using optical coherence tomography. Fluorescein angiography was also performed to confirm diagnosis. Patients were examined at 1 month after injection and monthly thereafter. Main outcome measures included changes in BCVA and CFT. Safety was assessed by ophthalmic examination and report of systemic adverse effects.

Results

There was a statistically significant difference in BCVA (p<0.001) and CFT (p<0.001) before and after the ranibizumab injection at the end of the follow-up of 13.4 ± 3.2 months. One injection appeared to be sufficient for the resolution of macular edema and absorption of hemorrhages. No observable ocular or systemic side effects were found. One patient developed foveal atrophy.

Conclusions

Intravitreal ranibizumab seems to be effective and safe for the treatment of symptomatic RAM.
Optic Disc Drusen: Longitudinal Aspects, with Emphasis on Visual Field Constriction and Enlarged Blind Spot: A Retrospective Hospital-Based Clinical Series
Authors: Fledelius Hans C.
Published: September 2016

Purpose

To examine long-term data on optic disc drusen (ODD) from an outpatient hospital series that indicated more cases with advanced visual field constriction than is apparent from other clinical reports. The underlying pathophysiology is discussed, also with regard to enlarged blind spot, which, in view of the small disc at risk, may seem a paradox.

Methods

This is an observational retrospective study on an eye clinic series (n = 49), focusing on visual acuity, kinetic/static perimetry, and longitudinal trends, to include the question of eventual visual incapacity.

Results

Forty-nine patients (32 female and 17 male; bilateral ODD in 45) aged 5-76 years (median age 29 years for both sexes) were included in the study. Observation time was 1-54 years, with serial data recorded over at least 3 years in 25 patients. Visual field defects were found in 32 patients, with ODD considered responsible for the visual field defects demonstrated. Advanced unilateral concentric constriction (for the largest Goldmann object) was recorded in 10 patients, and bilaterally in 2. With regard to nonexplanatory side diagnoses, 2 patients had pituitary adenoma, 1 had a cavernous sinus meningioma, and 1 had neurosurgery for an arachnoid cyst.

Conclusions

We found more cases of marked visual field constriction than reported in other clinical series. A few such cases appeared acute and vascular, but the main trend was clinically quiet over time. All 49 patients could manage visually in daily life.
Simulation of Panretinal Laser Photocoagulation Using Geometric Methods for Calculating the Photocoagulation Index
Authors: Nishida Kentaro , Sakaguchi Hirokazu , Kamei Motohiro , Shiraki Nobuhiko , Oura Yoshihito , Wakabayashi Taku , Hara Chikako , Fukushima Yoko , Sato Tatsuhiko , Sayanagi Kaori , Sato Shigeru , Fukuda Masakatsu , Nishida Kohji
Published: September 2016

Purpose

To establish geometrically based methods for simulating panretinal laser photocoagulation (PRP) for the photocoagulation index.

Methods

A formula for calculating the curved surface area of a spherical dome was used for the simulation. If the radius of the dome is c and the height of the dome is h, then the curved surface area (S) of the dome is S = π (c2 + h2). We calculated the area of the whole retina using this formula and the anatomical dimensions of the standard eyeball. To simulate PRP with a 400-μm spot on the retina with 1-spot spacing, we drew 400-μm-diameter circles, separated by 400 μm, on a retinal map. We calculated the ratio of the total retinal photocoagulated area to the whole retina, termed the photocoagulation index, in order to investigate the impact of the extent of the photocoagulated area and the pulse duration on PRP.

Results

The whole retinal area was 1,092 mm2. The numbers of spots in the scattered and full-scattered PRP were 1,222 and 1,814, respectively. The photocoagulation index was 14.1% and 20.9% for scattered and full-scattered PRP, respectively. These values changed to 14.3% (5.6%) and 21.3% (8.3%), respectively, for PRP with a 100-ms pulse or a 20-ms pulse.

Conclusions

This method will be useful for investigating the impact of various PRP parameters (duration, spacing, intensity of burns, extent of photocoagulated area, etc.) on the photocoagulation index.
High Serum Ion Levels in Conserve plus Big Femoral Head Cemented Total Hip Arthroplasty
Authors: Somers Jan F.A. , Van Der Straeten Catherine , De Coninck Luc
Published: September 2016

Aim

We report the short-term clinical, radiographic and ion level data of the Conserve Plus metal-on-metal (MoM) big femoral head (BFH) total hip arthroplasty (THA), used with a cemented cobalt-chrome (Co-Cr) Profemur Xm stem and a titanium (Ti) modular neck.

Results

In a consecutive series of 40 hips, survivorship at 3 years was 92.5% with revision for any reason. Average Harris Hip Score was 91.3. There were no implant loosenings. No osteolysis was observed. 5 patients had signs of adverse local tissue reaction (ALTR); their clinical scores were not different from the whole cohort. All but 1 patient had their Co serum ion levels measured. The average Co level was 14,1 μg/l (range 0.9-29.0; median 13.0 μg/l). Clinical scores did not correlate with ion level data. A comparative group of 42 hip resurfacing arthroplasties from the same manufacturer had significantly lower serum Co levels: 1.51 μg/l (range 0.9-4.0; median 0.9 μg/l).

Conclusions

All patients with the MoM BFH THA design should be followed regularly and should have ion level testing.