bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical-microphysical properties of Saharan dust aerosols and composition relationship using a multi-wavelength Raman lidar, in situ sensors and modelling: a case study analysis
Authors: Papayannis A. , Mamouri R. E. , Amiridis V. , Remoundaki E. , Tsaknakis G. , Kokkalis P. , Veselovskii I. , Kolgotin A. , Nenes A. , Fountoukis C.
Published: May 2012

Abstract. A strong Saharan dust event that occurred over the city of Athens, Greece (37.9° N, 23.6° E) between 27 March and 3 April 2009 was followed by a synergy of three instruments: a 6-wavelength Raman lidar, a CIMEL sun-sky radiometer and the MODIS sensor. The BSC-DREAM model was used to forecast the dust event and to simulate the vertical profiles of the aerosol concentration. Due to mixture of dust particles with low clouds during most of the reported period, the dust event could be followed by the lidar only during the cloud-free day of 2 April 2009. The lidar data obtained were used to retrieve the vertical profile of the optical (extinction and backscatter coefficients) properties of aerosols in the troposphere. The aerosol optical depth (AOD) values derived from the CIMEL ranged from 0.33–0.91 (355 nm) to 0.18–0.60 (532 nm), while the lidar ratio (LR) values retrieved from the Raman lidar ranged within 75–100 sr (355 nm) and 45–75 sr (532 nm). Inside a selected dust layer region, between 1.8 and 3.5 km height, mean LR values were 83 ± 7 and 54 ± 7 sr, at 355 and 532 nm, respectively, while the Ångström-backscatter-related (ABR355/532) and Ångström-extinction-related (AER355/532) were found larger than 1 (1.17 ± 0.08 and 1.11 ± 0.02, respectively), indicating mixing of dust with other particles. Additionally, a retrieval technique representing dust as a mixture of spheres and spheroids was used to derive the mean aerosol microphysical properties (mean and effective radius, number, surface and volume density, and mean refractive index) inside the selected atmospheric layers. Thus, the mean value of the retrieved refractive index was found to be 1.49( ± 0.10) + 0.007( ± 0.007)i, and that of the effective radiuses was 0.30 ± 0.18 μm. The final data set of the aerosol optical and microphysical properties along with the water vapor profiles obtained by Raman lidar were incorporated into the ISORROPIA II model to provide a possible aerosol composition consistent with the retrieved refractive index values. Thus, the inferred chemical properties showed 12–40% of dust content, sulfate composition of 16–60%, and organic carbon content of 15–64%, indicating a possible mixing of dust with haze and smoke. PM10 concentrations levels, PM10 composition results and SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray) analysis results on sizes and mineralogy of particles from samples during the Saharan dust transport event were used to evaluate the retrieval.
Comparative evaluation of the impact of WRF/NMM and WRF/ARW meteorology on CMAQ simulations for PM2.5 and its related precursors during the 2006 TexAQS/GoMACCS study
Authors: Yu S. , Mathur R. , Pleim J. , Pouliot G. , Wong D. , Eder B. , Schere K. , Gilliam R. , Rao S. T.
Published: May 2012

Abstract. This study presents a comparative evaluation of the impact of WRF-NMM and WRF-ARW meteorology on CMAQ simulations of PM2.5, its composition and related precursors over the eastern United States with the intensive observations obtained by aircraft (NOAA WP-3), ship and surface monitoring networks (AIRNow, IMPROVE, CASTNet and STN) during the 2006 TexAQS/GoMACCS study. The results at the AIRNow surface sites show that both ARW-CMAQ and NMM-CMAQ reproduced day-to-day variations of observed PM2.5 and captured the majority of observed PM2.5 within a factor of 2 with a NMB value of −0.4% for ARW-CMAQ and −18% for NMM-CMAQ. Both models performed much better at the urban sites than at the rural sites, with greater underpredictions at the rural sites. Both models consistently underestimated the observed PM2.5 at the rural IMPROVE sites by −1% for the ARW-CMAQ and −19% for the NMM-CMAQ. The greater underestimations of SO42−, OC and EC by the NMM-CMAQ contributed to increased underestimation of PM2.5 at the IMPROVE sites. The NMB values for PM2.5 at the STN urban sites are 15% and −16% for the ARW-CMAQ and NMM-CMAQ, respectively. The underestimation of PM2.5 at the STN sites by the NMM-CMAQ mainly results from the underestimations of the SO42−, NH4+ and TCM components, whereas the overestimation of PM2.5 at the STN sites by the ARW-CMAQ results from the overestimations of SO42−, NO3−, and NH4+. The Comparison with WP-3 aircraft measurements reveals that both ARW-CMAQ and NMM-CMAQ have very similar model performance for vertical profiles for PM2.5 chemical components (SO42−, NH4+) and related gaseous species (HNO3, SO2, NH3, isoprene, toluene, terpenes) as both models used the same chemical mechanisms and emissions. The results of ship along the coast of southeastern Texas over the Gulf of Mexico show that both models captured the temporal variations and broad synoptic change seen in the observed HCHO and acetaldehyde with the means NMB <30% most of the time but they consistently underestimated terpenes, isoprene, toluene and SO2.
Changes in black carbon deposition to Antarctica from two high-resolution ice core records, 1850–2000 AD
Authors: Bisiaux M. M. , Edwards R. , McConnell J. R. , Curran M. A. J. , Van Ommen T. D. , Smith A. M. , Neumann T. A. , Pasteris D. R. , Penner J. E. , Taylor K.
Published: May 2012

Abstract. Refractory black carbon aerosols (rBC) emitted by biomass burning (fires) and fossil fuel combustion, affect global climate and atmospheric chemistry. In the Southern Hemisphere (SH), rBC is transported in the atmosphere from low- and mid-latitudes to Antarctica and deposited to the polar ice sheet preserving a history of emissions and atmospheric transport. Here, we present two high-resolution Antarctic rBC ice core records drilled from the West Antarctic Ice Sheet divide and Law Dome on the periphery of the East Antarctic ice sheet. Separated by ~3500 km, the records span calendar years 1850–2001 and reflect the rBC distribution over the Indian and Pacific ocean sectors of the Southern Ocean. Concentrations of rBC in the ice cores displayed significant variability at annual to decadal time scales, notably in ENSO-QBO and AAO frequency bands. The delay observed between rBC and ENSO variability suggested that ENSO does not directly affect rBC transport, but rather continental hydrology, subsequent fire regimes, and aerosol emissions. From 1850 to 1950, the two ice core records were uncorrelated but were highly correlated from 1950 to 2002 (cross-correlation coefficient at annual resolution: r = 0.54, p < 0.01) due to a common decrease in rBC variability. The decrease in ice-core rBC from the 1950s to late 1980s displays similarities with inventories of SH rBC grass fires and biofuel emissions, which show reduced emission estimates over that period.
Atmospheric sulphuric acid and neutral cluster measurements using CI-APi-TOF
Authors: Jokinen T. , Sipilä M. , Junninen H. , Ehn M. , Lönn G. , Hakala J. , Petäjä T. , Mauldin R. L. , Kulmala M. , Worsnop D. R.
Published: May 2012

Abstract. The first ambient measurements using nitrate ion based Chemical Ionization with the Atmospheric Pressure interface Time-Of-Flight mass spectrometer (CI-APi-TOF) for sulphuric acid and neutral cluster detection are presented. We have found CI-APi-TOF a highly stable and sensitive tool for molecular sulphuric acid detection. The lowest limit of detection for sulphuric acid was determined to be 3.6 × 104 molecules cm−3 for 15 min averaging. Signals from sulphuric acid clusters up to tetramer containing ammonia were also obtained but these were found to result from naturally charged clusters formed by ion induced clustering in the atmosphere during nucleation. Opposite to earlier studies with cluster mass spectrometers, we had no indication of neutral clusters. The reason is either less efficient charging of clusters in comparison to molecular sulphuric acid, or the low concentration of neutral clusters at our measurement site during these particular nucleation events. We show that utilizing high resolution mass spectrometry is crucial in separating the weak sulfuric acid cluster signal from other compounds.
Chemically-resolved aerosol eddy covariance flux measurements in urban Mexico City during MILAGRO 2006
Authors: Zalakeviciute R. , Alexander M. L. , Allwine E. , Jimenez J. L. , Jobson B. T. , Molina L. T. , Nemitz E. , Pressley S. N. , VanReken T. , Ulbrich I. M. , Velasco E. , Lamb B. K.
Published: May 2012

Abstract. As part of the MILAGRO 2006 field campaign, the exchange of atmospheric aerosols with the urban landscape was measured from a tall tower erected in a heavily populated neighborhood of Mexico City. Urban submicron aerosol fluxes were measured using an eddy covariance method with a quadrupole aerosol mass spectrometer during a two week period in March 2006. Nitrate and ammonium aerosol concentrations were elevated at this location near the city center compared to measurements at other urban sites. Significant downward fluxes of nitrate aerosol, averaging −0.2 μg m−2 s−1, were measured during daytime. The urban surface was not a significant source of sulfate aerosols. The measurements also showed that primary organic aerosol fluxes, approximated by hydrocarbon-like organic aerosols (HOA), displayed diurnal patterns similar to CO2 fluxes and anthropogenic urban activities. Overall, 47% of submicron organic aerosol emissions were HOA, 35% were oxygenated (OOA) and 18% were associated with biomass burning (BBOA). Organic aerosol fluxes were bi-directional, but on average HOA fluxes were 0.09 μg m−2 s−1, OOA fluxes were −0.002 μg m−2 s−1, and BBOA fluxes were −0.03 μg m−2 s−1. The average diurnal flux results showed that the 2006 gridded emissions inventory of Mexico City underestimates mid-day and evening rush hour emissions of submicron aerosols for the monitored neighborhood, but averaged daily, the emission inventory and flux measurements for this location were in close agreement.
Continuous measurements of methane mixing ratios from ice cores
Authors: Stowasser C. , Buizert C. , Gkinis V. , Chappellaz J. , Schüpbach S. , Bigler M. , Faïn X. , Sperlich P. , Baumgartner M. , Schilt A. , Blunier T.
Published: May 2012

Abstract. This work presents a new, field-deployable technique for continuous, high-resolution measurements of methane mixing ratios from ice cores. The technique is based on a continuous flow analysis system, where ice core samples cut along the long axis of an ice core are melted continuously. The past atmospheric air contained in the ice is separated from the melt water stream via a system for continuous gas extraction. The extracted gas is dehumidified and then analyzed by a Wavelength Scanned-Cavity Ring Down Spectrometer for methane mixing ratios. We assess the performance of the new measurement technique in terms of precision (±0.8 ppbv, 1σ), accuracy (±8 ppbv), temporal (ca. 100 s), and spatial resolution (ca. 5 cm). Using a firn air transport model, we compare the resolution of the measurement technique to the resolution of the atmospheric methane signal as preserved in ice cores in Greenland. We conclude that our measurement technique can resolve all climatically relevant variations as preserved in the ice down to an ice depth of at least 1980 m (66 000 yr before present) in the North Greenland Eemian Ice Drilling ice core. Furthermore, we describe the modifications, which are necessary to make a commercially available spectrometer suitable for continuous methane mixing ratio measurements from ice cores.
Imbalanced nutrients as triggers for black shale formation in a shallow shelf setting during the OAE 2 (Wunstorf, Germany)
Authors: Blumenberg M. , Wiese F.
Published: May 2012

Abstract. During the oceanic anoxic event 2 (OAE 2) in the mid-Cretaceous widespread black shale (BS) formation occurred, reflecting perturbations in major biogeochemical cycles. Here we present geochemical and biomarker data of the OAE 2 from a shelf setting situated at about 100 to 150 water depth (Wunstorf, Germany). Our data support that processes inducing BS deposition were related to orbital cyclicity in Wunstorf and that they were not restricted to the time of the OAE 2 carbon isotope excursion. Correlations of total organic carbon (TOC) and δ15N and high relative abundances of functionalized hopanoids (incl. 2-methylated structures) suggest that BS were formed during times of imbalanced nutrients with high phosphorus inputs and increased (cyano)bacterial nitrogen fixation. Periods of BS formation were also characterized by enhanced growth of dinoflagellates and bacteriovorous ciliates, the latter supporting the presence of a stratified water body. The lack of biomarkers specific for green-sulfur bacteria excludes photic zone euxinia during OAE 2 in Wunstorf. Conflicting maturities and biomarker distributions in kerogen and extractable organic matter and, interestingly, a negative correlation of the diagenetically resistant 2-methyl hopane hydrocarbons with TOC indicate a complex depositional setting at Wunstorf. In Wunstorf this might have been induced by high continental run-off during BS formation and the accompanying mobilisation of refractory OM from the shelfs and near shore areas.
The role of alkalinity generation in controlling the fluxes of CO2 during exposure and inundation on tidal flats
Authors: Faber P. A. , Kessler A. J. , Bull J. K. , McKelvie I. D. , Meysman F. J. R. , Cook P. L. M.
Published: May 2012

Abstract. Dissolved inorganic carbon, CO2 and alkalinity fluxes from intertidal sediments were investigated during periods of exposure and inundation, using laboratory core incubations, field data and reactive transport model simulations. In the incubations and field data, it was found that during periods of alkalinity production, the flux of dissolved inorganic carbon (DIC) out of the sediment was significantly greater during inundation periods. This alkalinity production was attributed to the accumulation of reduced sulfur species within the sediment. This finding was supported by computational simulations which indicated that large amounts of sulfate reduction and reduced solute burial (FeS) induce an alkalinity flux from the sediment during high tide conditions. As the fate of sulfide is controlled by Fe, the sensitivity of alkalinity flux to Fe concentrations was investigated, and it was found that amount of reactive Fe in the sediment was a major driver of net alkalinity production. The finding the CO2 fluxes can be significantly lower than total metabolism during exposure has implications for how total metabolism is quantified on tidal flats.
High-resolution interpolar difference of atmospheric methane around the Last Glacial Maximum
Authors: Baumgartner M. , Schilt A. , Eicher O. , Schmitt J. , Schwander J. , Spahni R. , Fischer H. , Stocker T. F.
Published: May 2012

Abstract. Reconstructions of past atmospheric methane concentrations are available from ice cores from both, Greenland and Antarctica. The difference observed between the two polar methane concentration levels is a valuable additional parameter which allows to constrain the geographical location of the responsible methane sources. Here we present new high-resolution methane records from the North Greenland Ice Core Project (NGRIP) and the European Project for Ice Coring in Antarctica (EPICA) Dronning Maud Land (EDML) ice cores covering Termination 1, the Last Glacial Maximum, and parts of the last glacial back to 32 000 years before present. Due to the high-resolution records the synchronisation between the ice cores from NGRIP and EDML is considerably improved and the interpolar concentration difference of methane is determined with unprecedented precision and temporal resolution. Relative to the mean methane concentration, we find a rather stable positive interpolar difference throughout the record with its minimum value of 3.7 ± 0.7 % between 21 900–21 200 years before present, which is higher than previously estimated in this interval close to the Last Glacial Maximum. This implies that Northern Hemisphere boreal wetland sources were never completely shut off during the peak glacial. Starting at 21 000 years before present, i.e. severval millenia prior to the transition into the Holocene, the relative interpolar difference becomes even more positive and stays at a fairly stable level of 6.5 ± 0.8 % during Termination 1. We hypothesise that the anti-correlation observed in the monsoon records from the Northern and Southern Hemispheres induces a methane source redistribution within lower latitudes, which could explain parts of the variations in the interpolar difference.
Pre-industrial and mid-Pliocene simulations with NorESM-L – AGCM simulations
Authors: Zhang Z. , Yan Q.
Published: May 2012

Abstract. In the Pliocene Model Intercomparison Project (PlioMIP), two sets of experiments are suggested. One includes a reference and a mid-Pliocene experiment run with atmosphere general circulation models (AGCM experiments, referred to as Experiments I), the other includes a pre-industrial and a mid-Pliocene experiment run with coupled ocean-atmosphere general circulation models (AOGCM experiments, referred to as Experiment II). In this paper, we describe the AGCM experiments with the atmosphere model in the low resolution version of the Norwegian Earth System Model (NorESM-L), and also assess the potential uncertainties in analyzing mid-Pliocene climate anomalies, due to choosing SST fields for the reference experiment. We carry out a mid-Pliocene experiment, a control experiment forced by the modern SST fields, and a pre-industrial experiment forced by the monthly SST fields from HadISST averaged between 1879 and 1900. Our experiments illustrate that the simulated mid-Pliocene global annual mean SAT is 17.1 °C. It is 2.5 °C warmer than the control experiment, but 2.7 °C warmer than the pre-industrial experiment. We find that the uncertainties in analyses of mid-Pliocene climate anomalies are small on a global scale, but still large on a regional scale. On the regional scale, these uncertainties should be noticed and assessed in future PlioMIP studies.
Estimation of overland flow metrics at semiarid condition: Patagonian Monte
Authors: Rossi M. J. , Ares J. O.
Published: May 2012

Abstract. Water infiltration and overland flow (WIOF) processes are relevant in considering water partition among plant life forms, the sustainability of vegetation and the design of sustainable hydrological management. WIOF processes in arid and semiarid regions present regional characteristic trends imposed by the prevailing physical conditions of the upper soil as evolved under water-limited climate. A set of plot-scale field experiments at the semi-arid Patagonian Monte (Argentina) was performed in order to estimate infiltration-overland descriptive flow parameters. The micro-relief of undisturbed field plots at z-scale <1 mm was characterized through close-range stereo-photogrammetry and geo-statistical modelling. The overland flow areas produced by experimental runoff events were video-recorded and the runoff speed was measured with ortho-image processing software. Antecedent and post-inflow moisture were measured, and texture, bulk density and physical properties of the soil at the upper vadose zone were estimated. Field data were used to calibrate a physically-based, time explicit model of water balance in the upper soil and overland flows with a modified Green-Ampt (infiltration) and Chezy's (overland flow) algorithms. Modelling results satisfy validation criteria based on the observed overland flow areas, runoff-speed, water mass balance of the upper vadose zone, infiltration depth, slope along runoff-plume direction, and depression storage intensity. The experimental procedure presented supplies plot-scale estimates of overland flow and infiltration intensities at various intensities of water input which can be incorporated in larger-scale hydrological grid-models of arid regions. Findings were: (1) Overland flow velocities as well as infiltration-overland flow mass balances are consistently modelled by considering variable infiltration rates corresponding to depression storage and/or non-ponded areas. (2) The statistical relations presented allow the estimation of theoretical hydrodynamic parameters (Chezy's frictional C, average overland flow depth d*) through measurable characteristics of the surface soil and overland flow kinetics. (3) A protocol of field experiments and coupled time-distributed modelling to 1–2 above is described. The methodology and results obtained in this study are probably relevant to similar arid-semiarid areas of the world.
The importance of glacier and forest change in hydrological climate-impact studies
Authors: Köplin N. , Schädler B. , Viviroli D. , Weingartner R.
Published: May 2012

Abstract. Changes in land cover alter the water balance components of a catchment, due to strong interactions between soils, vegetation and the atmosphere. Therefore, hydrological climate impact studies should also integrate scenarios of associated land cover change. To reflect two severe climate-induced changes in land cover, we applied scenarios of glacier retreat and forest cover increase that were derived from the temperature signals of the climate scenarios used in this study. The climate scenarios consist of ten regional climate models from the ENSEMBLES project; their respective temperature and precipitation deltas are used to run a hydrological model. The relative importance of each of the three types of scenarios (climate, glacier, forest) is assessed through an analysis of variance (ANOVA). Altogether, 15 mountainous catchments in Switzerland are analysed, exhibiting different degrees of glaciation during the control period (0–51%) and different degrees of forest cover increase under scenarios of change (12–55% of the catchment area). The results show that even an extreme change in forest cover is negligible with respect to changes in runoff, but it is crucial as soon as evaporation or soil moisture is concerned. For the latter two variables, the relative impact of forest change is proportional to the magnitude of its change. For changes that concern 35% of the catchment area or more, the effect of forest change on summer evapotranspiration is equally or even more important than the climate signal. For catchment with a glaciation of 10% or more in the control period, the glacier retreat significantly determines summer and annual runoff. The most important source of uncertainty in hydrological climate impact studies is the climate scenario, though, and it is highly recommended to apply an ensemble of climate scenarios in impact studies. The results presented here are valid for the climatic region they were tested for, i.e. a humid, mid-latitude mountainous environment. They might be different for regions where the evaporation is a major component of the water balance, for example. Nevertheless, a hydrological climate-impact study that assesses the additional impacts of forest and glacier change is new so far and provides insight into the question whether or not it is necessary to account for land cover changes as part of climate change impacts on hydrological systems.
No evidence of increased fire risk due to agricultural land abandonment in Sardinia (Italy)
Authors: Ricotta C. , Guglietta D. , Migliozzi A.
Published: May 2012

Abstract. Different land cover types are related to different levels of fire hazard through their vegetation structure and fuel load composition. Therefore, understanding the relationships between landscape changes and fire behavior is of crucial importance for developing adequate fire fighting and fire prevention strategies for a changing world. In the last decades the abandonment of agricultural lands and pastoral activities has been the major driver of landscape transformations in Mediterranean Europe. As agricultural land abandonment typically promotes an increase in plant biomass (fuel load), a number of authors argue that vegetation succession in abandoned fields and pastures is expected to increase fire hazard. In this short paper, based on 28 493 fires in Sardinia (Italy) in the period 2001–2010, we show that there is no evidence of increased probability of fire ignition in abandoned rural areas. To the contrary, in Sardinia the decreased human impact associated with agricultural land abandonment leads to a statistically significant decrease of fire ignition probability.
Recent high-energy marine events in the sediments of Lagoa de Óbidos and Martinhal (Portugal): recognition, age and likely causes
Authors: Costa P. J. M. , Leroy S. A. G. , Dinis J. L. , Dawson A. G. , Kortekaas S.
Published: May 2012

Abstract. A key issue in coastal hazards research is the need to distinguish sediments deposited by past extreme storms from those of past tsunamis. This study contributes to this aim by investigating patterns of sedimentation associated with extreme coastal flood events, in particular, within the Lagoa de Óbidos (Portugal). The recent stratigraphy of this coastal lagoon was studied using a wide range of techniques including visual description, grain-size analysis, digital and x-ray photography, magnetic susceptibility and geochemical analysis. The sequence was dated by 14C, 210Pb and Optically Stimulated Luminescence. Results disclose a distinctive coarser sedimentary unit, within the top of the sequence studied, and shown in quartz sand by the enrichment of elements with marine affinity (e.g., Ca and Na) and carbonates. The unit fines upwards and inland, thins inland and presents a sharp erosive basal contact. A noticeable post-event change in the sedimentary pattern was observed. The likely agent of sedimentation is discussed here and the conceivable association with the Great Lisbon tsunami of AD 1755 is debated, while a comparison is attempted with a possibly synchronous deposit from a tsunami in Martinhal (Algarve, Portugal). The possibility of a storm origin is also discussed in the context of the storminess of the western Portuguese coast and the North Atlantic Oscillation. This study highlights certain characteristics of the sedimentology of the deposits that may have a value in the recognition of extreme marine inundation signatures elsewhere in the world.
Assessment of risks of loose landslide deposits formed by the 2008 Wenchuan earthquake
Authors: Zhang S. , Zhang L. M. , Peng M. , Zhang L. L. , Zhao H. F. , Chen H. X.
Published: May 2012

Abstract. A Geographic Information System (GIS)-based quantitative risk assessment methodology was adopted to evaluate the risks of loose deposits formed by the 2008 Wenchuan earthquake along a highway near the epicenter. A total of 305 loose deposits with a total volume of 4.0 × 107 m3 has been identified. A physical model was used to determine the failure probability of these loose deposits under six rainfall scenarios, assuming the loose deposits as infinite slopes. The calculated probability of rain-induced slope failures is verified by the recorded landslides at the same site during a storm in 2010. Seventy-nine out of the 112 rain-induced loose deposit failures are predicted by the reliability analysis, with an accuracy of 71%. The results of reliability analysis and information on the consequence of these rain-induced landslides enable the estimation of the annual societal and individual risks of the loose deposits. Under the rainfall scenarios of 30 mm/12 h and 70 mm/12 h, the estimated annual societal risks reach 8.8 and 7.5, respectively, and the individual risks reach 0.05 and 0.04, respectively, which are very high compared with present risk acceptance criteria. The preliminary assessment provides a benchmark for studying the long-term risks of these loose deposits and engineering decision.
Verification of precipitation forecasts of MM5 model over Epirus, NW Greece, for various convective parameterization schemes
Authors: Sindosi O. A. , Bartzokas A. , Kotroni V. , Lagouvardos K.
Published: May 2012

Abstract. The mesoscale meteorological model MM5 is applied to 22 selected days with intense precipitation in the region of Epirus, NW Greece. At first, it was investigated whether and to what extend an increased horizontal resolution (from 8 to 2 km) improves the quantitative precipitation forecasts. The model skill was examined for the 12-h accumulated precipitation recorded at 14 meteorological stations located in Epirus and by using categorical and descriptive statistics. Then, the precipitation forecast skill for the 2 km grid was studied: (a) without and (b) with the activation of a convective parameterization scheme. From the above study, the necessity of the use of a scheme at the 2 km grid is assessed. Furthermore, three different convective parameterization schemes are compared: (a) Betts-Miller, (b) Grell and (c) Kain-Fritsch-2 in order to reveal the scheme, resulting in the best precipitation forecast skill in Epirus. Kain-Fritsch-2 and Grell give better results with the latter being the best for the high precipitation events.
Predictions for oil slicks detected from satellite images using MyOcean forecasting data
Authors: Zodiatis G. , Lardner R. , Solovyov D. , Panayidou X. , De Dominicis M.
Published: May 2012

Abstract. The MyOcean marine core service, implementing the Global Monitoring for Environment and Security (GMES) objectives, targets the provision of ocean state data from various platforms to assist, among other downscaled activities, the needs of the operational response to marine safety, particularly concerning oil spills. The MEDSLIK oil spill and trajectory prediction system makes use of the MyOcean regional and Cyprus Coastal Ocean Forecasting and Observing System (CYCOFOS) downscaled forecasting products for operational application in the Mediterranean and pre-operational use in the Black Sea. Advanced Synthetic Aperture Radar (ASAR) satellite remote-sensing images from European Space Agency (ESA) and European Maritime Safety Agency – CleanSeaNet (EMSA-CSN) provide the means for routine monitoring of the southern European seas for the detection of illegal oil discharges. MEDSLIK offers various ways, to be described in this paper, of coupling the Pan-European capacity for Ocean Monitoring and Forecasting (MyOcean) forecasting data with ASAR imageries to provide both forecasts and hindcasts for such remotely-observed oil slicks. The main concern will be the drift of the oil slick and also, in the case of the forecast mode, its diffusive spreading, although some attempt is also made to estimate the changes in the state of the oil. The successful link of the satellite-detected oil slicks with their operational predictions using the MyOcean products contributes to the operational response chain and the strengthening of maritime safety for accidental or illegal spills, in implementation of a Mediterranean decision support system for marine safety regarding oil spills.
New Optimum Humanoid Hand Design for Prosthetic Applications
Authors: El-Sheikh Mogeeb A. , Taher Mona F. , Metwalli Sayed M.
Published: May 2012

To address the need for a commercially feasible prosthetic hand, the current work presents the design of a new humanoid hand actuated using shape memory alloy (SMA) artificial muscle wires. The hand has 3 compliant fingers and a thumb attached to the palm. The palm structure is a novel design, which is based on the natural arches of the human hand to provide better grasping capabilities. A compact actuator module is proposed to house and cool the SMA wires. Design parameters of the hand were selected to maximize the work density. The hand is lightweight, low cost, and operates silently. It has functional opening and closing speeds and fingertip force.
Interleukin-8 (CXCL8) in Tumor Associated Non-Vascular Extracellular Fluids: Its Diagnostic and Prognostic Values. A Review
Authors: Kotyza Jaromír
Published: May 2012

Interleukin-8 (IL-8, CXCL8) was originally discovered as a powerful attractor and activator of polymorphonuclear leukocytes. It was soon recognized that IL-8 also affects proliferation and migration of cancer cells, tumor angiogenesis and metastasis, and that it is expressed in many cancerous cell types. IL-8 protein expression is usually increased in serum of cancer patients, but markedly higher concentrations are found in cancer-associated non-vascular extracellular fluids, such as pleural effusion, ascites and cyst fluid. Elevated concentrations of IL-8 are indicative of malignant processes also in cerebrospinal fluid, urine, saliva, interstitial fluid and cervicovaginal secretions. Higher IL-8 levels are typically found in high-grade peritumoral fluids rather than low-grade tumors and benign conditions, with the exception of inflammatory processes. In line with recent molecular biology investigations, it appears that the local IL-8 production is related to its malignant origin and to tumor progression. Hence, IL-8 in peritumoral fluid is to be taken into consideration while assessing tumor character and monitoring the tumor progression/remission status. Besides, the data here collected justify the attempts to find an IL-8-targeted inhibitory therapy.
Numerical Simulation of the Temperature and Stress Field Evolution Applied to the Field Assisted Sintering Technique
Authors: Allen J. B. , Walter C.
Published: May 2012

The field assisted sintering technique (FAST) is a high-amperage, low-voltage, powder consolidation technique that employs pulsed direct current and uniaxial pressure. Over the past several years, FAST has been successfully used to produce a variety of different materials including metals, composites, and ceramics. In this paper we present a transient finite element model of aluminum oxide sintering that incorporates a coupled electrical, thermal, and mechanical analysis that closely resembles the procedures used in physical experiments. Within this context, we outline the governing equations that pertain to a balanced energy equation and include the effects of thermal and electrical contact forces, radiation, and Joule heating. We couple this with the relevant equations pertaining to mechanical displacements and prescribe the necessary initial and boundary conditions for a complete solution. As part of our transient analysis, we also present our implementation of a proportional integral derivative controller, which (similar to actual experimental conditions) affords the use of a predetermined heating rate conditioned upon a variable voltage. Finally, we discuss implications relating to the temperature and stress fields and suggest possible avenues for improvement.
Constrained Parameters in Applications: Review of Issues and Approaches
Authors: Kopylev Leonid
Published: May 2012

This review article provides an introduction to statistical issues that arise when some statistical model parameters are constrained. This often happens in applications, in particular in testing for variance components (e.g., genomics) and construction of one-sided confidence intervals (e.g., environmental risk analysis). Heuristic explanations are provided, and a number of general and recent statistical results that appeared in statistical literature are summarized for use in applications. Simulation results are shown for illustration of consequences of ignoring parameters on the boundary. Special attention is paid to likelihood ratio tests, but other approaches to confidence interval construction, such as Wald, bootstrap, and Bayesian are also briefly discussed. This paper presents examples from the risk assessment field and genomics, but all conclusions apply to whenever one-sided testing is conducted. Recommendations are provided for dealing with parameters on the boundary for a range of situations.
Analytical Solutions of the Slip Magnetohydrodynamic Viscous Flow over a Stretching Sheet by Using the Laplace–Adomian Decomposition Method
Authors: Ghehsareh Hadi Roohani , Abbasbandy Saeid , Soltanalizadeh Babak
Published: May 2012

In this research, the Laplace-Adomian decomposition method (LADM) is applied for the analytical and numerical treatment of the nonlinear differential equation that describes a magnetohydrodynamic (MHD) flow under slip condition over a permeable stretching surface. The technique is well applied to approximate the similarity solutions of the problem for some typical values of model parameters. The obtained series solutions by the LADM are combined with the Pad´e approximation to improve the accuracy and enlarge the convergence domain of the obtained results. Through tables and figures, the efficiency of the presented method is illustrated.
New Computational Dynamics for Magnetohydrodynamics Flow over a Nonlinear Stretching Sheet
Authors: Khan Majid , Gondal Muhammad Asif
Published: May 2012

The main idea of the present article is to introduce a new computational technique, explicitly, the modified Laplace Pad´e decomposition method (MLPDM) which is a recipe of Laplace transformation, decomposition technique, and rational polynomial to offer new solution mechanism of magnetohydrodynamics (MHD) flow of an steady viscous, incompressible nonlinear stretching sheet. A good harmony among the attained solution and the exact solution has been verified.
A 53-year-old woman with a severe headache, bilateral eye pain, blurred vision, and photophobia
Authors: Barros Pedro , Paris Liliana , Martins Joana , Tenedorio Paula
Published: May 2012

A 53-year-old woman presented to our emergency department with a severe headache, bilateral eye pain, blurred vision and photophobia. She started oral topiramate 25 mg daily for migraine prophylaxis the evening before. Symptoms started immediately upon awakening, and she was brought to our emergency department. She reported a history of allergy to corticosteroids and gastric intolerance to oral nonsteroidal anti-inflammatory drugs (NSAIDs).
Aprendizagem significativa no ensino fundamental - uma experiência no ensino da ciência
Authors: Carvalho Laura de
Published: May 2012

This work presents an experience about orientation at elementary and intermediary teaching school,which was made by use of Ausubel’s learning theory. The purpose of this work was let the teacher Knows aboutthe importance in Keeping the value of previous Knowledge of the students, and to relate news contents todeflagrate a significative learning, and furthermore, to make possible the planing of diversified learning situations.It Was presumed that, in the teaching and learning process of Sciences, one of the main goals is the assimilation ofthe systematized concepts. At the first stage, it was identified the basic concepts of the foreseen contents for theselected series, though analysis of the São Paulo’s Sciences teaching curricular purpose, SE/CENP, giving priorityto the teacher’s planning and select contents to the search, replanning of unity and application of Ausubel’s learningtheory, with emphasis of the student’s previous Knowledge. These students, 24 fernale and 11 male, between 11and 13 years old approximately, attended the fifth series at a public school at São Paulo state. Using the principleof progressive differentiation, it was planned the contents looking to show, at first, the broad concepts of one unityof Sciences and afterward, the narrow concepts. By way of whole reconciliation it was explained the similarity anddifferences between allied concepts. The utilization of conceptuals maps was na important and fundamentaltechnique to the investigation. The concepts were introduced from the students had known before. Conclusionspointed out towards a significative learning of the basic concepts on Human Reprodution for the most part of thestudents, trough verification and comparation between the results pre and post tests and the conceptual evolutionof the group.
Tarefas de casa: reprodução ou construção do conhecimento escolar ?
Authors: Wiezzel Andréia Cristiane Silva
Published: May 2012

The present article investigates the practice of the homework inside the educational process, inclassrooms of the first four séries of the fundamental teaching. Having as referencial the notion of significantlearning, proposal and developed by David Ausubel, it analyzes, if the homework would have some contributionin the sense of providing such learning to the student or if it is linked to a mechanical learning. The studyconsidered point of view of the three segments directy invilved in the problem: teachers, parents and students,under interview form. Beginning of those data also of systematic observations in classrooms were analysed, amongother aspects, the purposes of the homework, types and amount. The data show the explanation need to theteachers about the subject, which has not happened in courses of teacher’s formation and in the own educationalliterature.
CONSTRUINDO HISTÓRIA NO ENSINO FUNDAMENTAL - A QUESTÃO DOS EIXOS TEMÁTICOS
Authors: Neves Vilma Fernandes
Published: May 2012

This article presents a dialogue on the production of the history and the history lived by different human groups in different times and spaces. In this perspective, we try to apprehend the historian's situation while subject of this time, as a witness of history and its specialist. We apply the concept of thematic axes and make suggestions for its implementation in the context of the classroom during the first school grades of the elementary school.
Robust optimal control of uncertain nonaffine MIMO nonlinear discrete‐time systems with application to HCCI engines
Authors: Zargarzadeh H. , Jagannathan S. , Drallmeier J.
Published: May 2012

MIMO optimal control of unknown nonaffine nonlinear discrete‐time systems is a challenging problem owing to the presence of control inputs inside the unknown nonlinearity. In this paper, the nonaffine nonlinear discrete‐time system is transformed to an affine‐like equivalent nonlinear discrete‐time system in the input–output form. Next, a forward‐in‐time Hamilton–Jacobi–Bellman equation‐based optimal approach, without using value and policy iterations, is developed to control the affine‐like nonlinear discrete‐time system by using both NN as an online approximator and output measurements alone. To overcome the need to know the control gain matrix in the optimal controller, a new online discrete‐time NN identifier is introduced. The robustness of the overall closed‐loop system is shown via singular perturbation analysis by using an additional auxiliary term to mitigate the higher‐order terms. Lyapunov stability of the overall system, which includes the online identifier and robust control term, demonstrates that the closed‐loop signals are bounded and the approximate control input approaches the optimal control signal with a bounded error. The proposed optimal control approach is applied to a cycle‐by‐cycle discrete‐time representation of an experimentally validated homogeneous charge compression ignition fuel‐flexible engine whose dynamics are modeled as uncertain nonlinear, nonaffine, and MIMO discrete‐time system. Simulation results are included to demonstrate the efficacy of the approach in presence of actuator disturbances. Copyright © 2012 John Wiley & Sons, Ltd.
Quantification of Quantum Efficiency and Energy Losses in Low Bandgap Polymer:Fullerene Solar Cells with High Open‐Circuit Voltage
Authors: Vandewal Koen , Ma Zaifei , Bergqvist Jonas , Tang Zheng , Wang Ergang , Henriksson Patrik , Tvingstedt Kristofer , Andersson Mats R. , Zhang Fengling , Inganäs Olle
Published: May 2012

In organic solar cells based on polymer:fullerene blends, energy is lost due to electron transfer from polymer to fullerene. Minimizing the difference between the energy of the polymer exciton (ED*) and the energy of the charge transfer state (ECT) will optimize the open‐circuit voltage (Voc). In this work, this energy loss ED*‐ECT is measured directly via Fourier‐transform photocurrent spectroscopy and electroluminescence measurements. Polymer:fullerene photovoltaic devices comprising two different isoindigo containing polymers: P3TI and PTI‐1, are studied. Even though the chemical structures and the optical gaps of P3TI and PTI‐1 are similar (1.4 eV–1.5 eV), the optimized photovoltaic devices show large differences in Voc and internal quantum efficiency (IQE). For P3TI:PC71BM blends a ED*‐ECT of ∼ 0.1 eV, a Voc of 0.7 V and an IQE of 87% are found. For PTI‐1:PC61BM blends an absence of sub‐gap charge transfer absorption and emission bands is found, indicating almost no energy loss in the electron transfer step. Hence a higher Voc of 0.92 V, but low IQE of 45% is obtained. Morphological studies and field dependent photoluminescence quenching indicate that the lower IQE for the PTI‐1 system is not due to a too coarse morphology, but is related to interfacial energetics. Losses between ECT and qVoc due to radiative and non‐radiative recombination are quantified for both material systems, indicating that for the PTI‐1:PC61BM material system, Voc can only be increased by decreasing the non‐radiative recombination pathways. This work demonstrates the possibility of obtaining modestly high IQE values for material systems with a small energy offset (<0.1 eV) and a high Voc.
Atmospheric‐Pressure Chemical Vapor Deposition of Iron Pyrite Thin Films
Authors: Berry Nicholas , Cheng Ming , Perkins Craig L. , Limpinsel Moritz , Hemminger John C. , Law Matt
Published: May 2012

Iron pyrite (cubic FeS2) is a promising candidate absorber material for earth‐abundant thin‐film solar cells. In this report, single‐phase, large‐grain, and uniform polycrystalline pyrite thin films are fabricated on glass and molybdenum‐coated glass substrates by atmospheric‐pressure chemical vapor deposition (AP‐CVD) using the reaction of iron(III) acetylacetonate and tert‐butyl disulfide in argon at 300 °C, followed by sulfur annealing at 500–550 °C to convert marcasite impurities to pyrite. The pyrite‐marcasite phase composition depends strongly on the concentration of sodium in the growth substrate and the sulfur partial pressure during annealing. Phase and elemental composition of the films are characterized by X‐ray diffraction, Raman spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, Rutherford backscattering spectrometry, and X‐ray photoelectron spectroscopy. The in‐plane electrical properties are surprisingly insensitive to phase and elemental impurities, with all films showing p‐type, thermally activated transport with a small activation energy (≈30 meV), a room‐ temperature resistivity of ≈1 Ω cm, and low mobility. These ubiquitous electrical properties may result from robust surface effects. These CVD pyrite thin films are well suited to fundamental electrical studies and the fabrication of pyrite photovoltaic device stacks.