Cloud-resolving simulations of mercury scavenging and deposition in thunderstorms

This study examines dynamical and microphysical features of convective clouds that affect mercury (Hg) wet scavenging and concentrations in rainfall. Using idealized numerical model simulations in the Regional Atmospheric Modeling System (RAMS), we diagnose vertical transport and scavenging of soluble Hg species – gaseous oxidized mercury (GOM) and particle-bound mercury (HgP), collectively Hg(II) – in thunderstorms under typical environmental conditions found in the Northeast and Southeast United States (US). Mercury scavenging efficiencies from various initial altitudes are diagnosed for a case study of a typical strong convective storm in the Southeast US. Assuming that soluble mercury concentrations are initially vertically uniform, the model results suggest that 60% of mercury deposited to the surface in rainwater originates from above the boundary layer (> 2 km). The free troposphere could supply a larger fraction of mercury wet deposition if GOM and HgP concentrations increase with altitude. We use radiosonde observations in the Northeast and Southeast to characterize three important environmental characteristics that influence thunderstorm morphology: convective available potential energy (CAPE), vertical shear (0–6 km) of horizontal wind (SHEAR) and precipitable water (PW). The Southeast US generally has lower SHEAR and higher CAPE and PW. We then use RAMS to test how PW and SHEAR impact mercury scavenging and deposition, while keeping the initial Hg(II) concentrations fixed in all experiments. We found that the mercury concentration in rainfall is sensitive to SHEAR with the nature of sensitivity differing depending upon the PW. Since CAPE and PW cannot be perturbed independently, we test their combined influence using an ensemble of thunderstorm simulations initialized with environmental conditions for the Northeast and Southeast US. These simulations, which begin with identical Hg(II) concentrations, predict higher mercury concentrations in rainfall from thunderstorms forming in the environmental conditions over the Southeast US compared to the Northeast US. A final simulation of a stratiform rain event produces lower mercury concentrations than in thunderstorms forming in environments typical of the Southeast US. The stratiform cloud scavenges mercury from the lowest ~ 4 km of the atmosphere, while thunderstorms scavenge up to ~ 10 km

Computational fluid dynamic modeling of 100ml and scaled-down 10ml stirred suspension bioreactors enables prediction of embryonic stem cell characteristics

There is a growing necessity for cell cultivation using bioreactors to translate laboratory based culture protocols into reproducible, scalable, and robust bioprocesses. Stirred suspension bioreactors offer several advantages over planar static cultures, including: reduced labour and operating costs, reduced space requirements, greater cellular homogeneity, and increased cell density per volume [1]. An important consideration when using stirred suspension bioreactors is mechanical stimulation. Fluid shear at the fluid-cell interface triggers cellular responses through mechanotransduction and can modulate stem cell proliferation and differentiation. However, if the shear stress caused by the impeller exceeds the tolerance limit of the cells, it causes cell damage and death, resulting in a lower quality and yield of cells. The shear rate distribution depends on bioreactor geometry, impeller agitation rate, cell density, and cell media viscosity [2]. Current scale-up protocols to predict agitation rates rely on maximum values of hydrodynamic variables, which occur only at the impeller tip. The volume averaged shear stress and maximum shear stress differ greatly, and cells dispersed within the liquid experience different local and global forces. This makes it difficult to predict how cells will respond to changes in bioreactor geometries and sizes. Profiling distributed and average forces in the bioreactor is critical to ensure quality and yield in cell manufacturing. Hydrodynamics, specifically velocities, shear rates, and energy dissipation rates, can be studied using computational fluid dynamic (CFD) modeling. Please click Additional Files below to see the full abstract

Hindcast of oil-spill pollution during the Lebanon crisis in the Eastern Mediterranean, July–August 2006

MOON (Mediterranean Operational Oceanography Network http://www.moon-oceanforecasting.eu) pro- vides near-real-time information on oil-spill detection (ocean color and SAR) and predictions [ocean fore- casts (MFS and CYCOFOS) and oil-spill predictions (MEDSLIK)]. We employ this system to study the Lebanese oil-pollution crisis in summer 2006 and thus to assist regional and local decision makers in Europe, regionally and locally. The MEDSLIK oil-spill predictions obtained using CYCOFOS high-resolution ocean fields are compared with those obtained using lower-resolution MFS hydrodynamics, and both are validated against satellite observations. The predicted beached oil distributions along the Lebanese and Syrian coasts are compared with in situ observations. The oil-spill predictions are able to simulate the northward movement of the oil spill, with the CYCO- FOS predictions being in better agreement with satellite observations. Among the free MEDSLIK param- eters tested in the sensitivity experiments, the drift factor appears to be the most relevant to improve the quality of the results.The paper was produced using the INGV MFS forecasting-sys- tem product and the OC-UCY CYCOFOS forecasting-system prod- ucts. The MODIS satellite data products were processed at the GOS-CNR-ISAC Rome laboratory using the SeaDAS software devel- oped by NASA GSFC, Greenbelt, Maryland, the HDFLook software developed by The Laboratoire d’Optique Atmosphérique, Univer- sity of Lille, France, and the MS2GT tool box developed by the Uni- versity of Colorado. Procedures for oil-spill detection were developed in the ENVI environment. Processed ENVISAT-ASAR data were made available by Telespazio and JRC. Part of this work was carried out with the support of the PRIMI project (ASI Contract No. I/094/06/0) financed by the Italian Space Agency (ASI).In press4.6. Oceanografia operativa per la valutazione dei rischi in aree marineJCR Journalreserve

Hindcast of oil-spill pollution during the Lebanon crisis in the Eastern Mediterranean, July–August 2006

MOON (Mediterranean Operational Oceanography Network http://www.moon-oceanforecasting.eu) provides near-real-time information on oil-spill detection (ocean color and SAR) and predictions [ocean forecasts (MFS and CYCOFOS) and oil-spill predictions (MEDSLIK)]. We employ this system to study the Lebanese oil-pollution crisis in summer 2006 and thus to assist regional and local decision makers in Europe, regionally and locally. The MEDSLIK oil-spill predictions obtained using CYCOFOS high-resolution ocean fields are compared with those obtained using lower-resolution MFS hydrodynamics, and both are validated against satellite observations. The predicted beached oil distributions along the Lebanese and Syrian coasts are compared with in situ observations. The oil-spill predictions are able to simulate the northward movement of the oil spill, with the CYCOFOS predictions being in better agreement with satellite observations. Among the free MEDSLIK parameters tested in the sensitivity experiments, the drift factor appears to be the most relevant to improve the quality of the results.Published140–153JCR Journalrestricte

Hindcast of Oil Spill Pollution during the Lebanon Crisis, July-August 2006

The Mediterranean Operational Oceanography Network (MOON ) provides near-real-time information on oil spill detection and predictions that have been used during the Lebanese oil pollution crisis in summer 2006. A MOON decision support system for oil spill monitoring and prediction comprising ocean colour satellite and SAR images, ocean current forecast (MFS-Mediterranean Forecasting System and CYCOFOS-CYprus Coastal Ocean Forecasting & Observing System) and the MEDSLIK oil spill model has been developed. The oil spill predictions obtained with MEDSLIK coupled to the CYCOFOS high-resolution ocean fields are compared with the oil spill predictions obtained using the lower resolution MFS hydrodynamics and both are validated against satellite observations. The predicted beached oil quatity along the Lebanese and Syrian coasts are compared with the in-situ observations. It is found that predictions with both CYCOFOS and MFS ar capable to simulate the northward movement of the oil, with the higher resolution CYCOFOS predictions in better agreement with satellite observations. Among the free MEDSLIK oil spill parameters tested in the sensitivity experiments there are the wind corrections (wind factor and angle) and the depth of coupling between eulerian fields and wind correction. Among them the drift factor appeared the most relevant in order to improve the quality of results suggesting that operational models such as MFS and CYCOFOS still lack of enought resolution and physical process at the air-sea interface. The oil moved from Lat 33°40'N Lon 35°24.75'E northward toward Syria, which was reached in 10 days at Lat 34° 38.451'N Lon 35° 58.377'E; the oil movement is followed up to August 6 when the oil reached 35.5°N.Not submitted4.6. Oceanografia operativa per la valutazione dei rischi in aree marineJCR Journalope

QoS Equalization in a W-CDMA Cell Supporting Calls of Innite or Finite Sources with Interference Cancelation, Journal of Telecommunications and Information Technology, 2014, nr 3

In this paper, a multirate loss model for the calculation of time and call congestion probabilities in a Wideband Code Division Multiple Access (W-CDMA) cell is considered. It utilizes the Bandwidth Reservation (BR) policy and supports calls generated by an innite or nite number of users. The BR policy achieves QoS equalization by equalizing congestion probabilities among calls of dierent service-classes. In the proposed models a multiple access interference is considered, and the notion of local blocking, user's activity and interference cancelation. Although the analysis of the proposed models reveals that the steady state probabilities do not have a product form solution, the authors show that the calculation of time and call congestion probabilities can be based on approximate but recursive formulas, whose accuracy is veried through simulation and found to be quite satisfactory

Overview of Plasma Lens Experiments and Recent Results at SPARC_LAB

Beam injection and extraction from a plasma module is still one of the crucial aspects to solve in order to produce high quality electron beams with a plasma accelerator. Proper matching conditions require to focus the incoming high brightness beam down to few microns size and to capture a high divergent beam at the exit without loss of beam quality. Plasma-based lenses have proven to provide focusing gradients of the order of kT/m with radially symmetric focusing thus promising compact and affordable alternative to permanent magnets in the design of transport lines. In this paper an overview of recent experiments and future perspectives of plasma lenses is reported

Climatic Feedbacks and Desertification: The Mediterranean Model

Abstract Mesometeorological information obtained in several research projects in southern Europe has been used to analyze perceived changes in the western Mediterranean summer storm regime. A procedure was developed to disaggregate daily precipitation data into three main components: frontal precipitation, summer storms, and Mediterranean cyclogenesis. Working hypotheses were derived on the likely processes involved. The results indicate that the precipitation regime in this Mediterranean region is very sensitive to variations in surface airmass temperature and moisture. Land-use perturbations that accumulated over historical time and greatly accelerated in the last 30 yr may have induced changes from an open, monsoon-type regime with frequent summer storms over the mountains inland to one dominated by closed vertical recirculations where feedback mechanisms favor the loss of storms over the coastal mountains and additional heating of the sea surface temperature during summer. This, in turn, favors Mediterranean cyclogenesis and torrential rains in autumn–winter. Because these intense rains and floods can occur anywhere in the basin, perturbations to the hydrological cycle in any part of the basin can propagate to the whole basin and adjacent regions. Furthermore, present levels of air pollutants can produce greenhouse heating, amplifying the perturbations and pushing the system over critical threshold levels. The questions raised are relevant for the new European Union (EU) water policies in southern Europe and for other regions dominated by monsoon-type weather systems