Showing papers by "The Cyprus Institute published in 2009"

Severe ozone air pollution in the Persian Gulf region

Abstract: . Recently it was discovered that over the Middle East during summer ozone mixing ratios can reach a pronounced maximum in the middle troposphere. Here we extend the analysis to the surface and show that especially in the Persian Gulf region conditions are highly favorable for ozone air pollution. We apply the EMAC atmospheric chemistry-climate model to investigate long-distance transport and the regional formation of ozone. Further, we make use of available in situ and satellite measurements and compare these with model output. The results indicate that the region is a hot spot of photochemical smog where European Union air quality standards are violated throughout the year. Long-distance transports of air pollution from Europe and the Middle East, natural emissions and stratospheric ozone conspire to bring about relatively high background ozone mixing ratios. This provides a hotbed to strong and growing indigenous air pollution in the dry local climate, and these conditions are likely to get worse in the future.

High Dynamic Range Imaging and Low Dynamic Range Expansion for Generating HDR Content

Abstract: In the last few years, researchers in the field of High Dynamic Range (HDR) Imaging have focused on providing tools for expanding Low Dynamic Range (LDR) content for the generation of HDR images due to the growing popularity of HDR in applications, such as photography and rendering via Image-Based Lighting, and the imminent arrival of HDR displays to the consumer market. LDR content expansion is required due to the lack of fast and reliable consumer level HDR capture for still images and videos. Furthermore, LDR content expansion, will allow the re-use of legacy LDR stills, videos and LDR applications created, over the last century and more, to be widely available. The use of certain LDR expansion methods, those that are based on the inversion of Tone Mapping Operators (TMOs), has made it possible to create novel compression algorithms that tackle the problem of the size of HDR content storage, which remains one of the major obstacles to be overcome for the adoption of HDR. These methods are used in conjunction with traditional LDR compression methods and can evolve accordingly. The goal of this report is to provide a comprehensive overview on HDR Imaging, and an in depth review on these emerging topics.

Atmosphere‐ocean ozone exchange: A global modeling study of biogeochemical, atmospheric, and waterside turbulence dependencies

Abstract: Received 9 July 2008; revised 12 June 2009; accepted 17 July 2009; published 7 November 2009. [1] The significance of the removal of tropospheric ozone by the oceans, covering 2/3 of the Earth’s surface, has only been addressed in a few studies involving water tank, aircraft, and tower flux measurements. On the basis of results from these few observations of the ozone dry deposition velocity (VdO3), atmospheric chemistry models generally apply an empirical, constant ocean uptake rate of 0.05 cm s 1 . This value is substantially smaller than the atmospheric turbulent transport velocity for ozone. On the other hand, the uptake is higher than expected from the solubility of ozone in clean water alone, suggesting that there is an enhancement in oceanic ozone uptake, e.g., through a chemical destruction mechanism. We present an evaluation of a global-scale analysis with a new mechanistic representation of atmosphere-ocean ozone exchange. The applied atmosphere chemistry-climate model includes not only atmospheric but also waterside turbulence and the role of waterside chemical loss processes as a function of oceanic biogeochemistry. The simulations suggest a larger role of biogeochemistry in tropical and subtropical ozone oceanic uptake with a relative small temporal variability, whereas in midlatitude and high-latitude regions, highly variable ozone uptake rates are expected because of the stronger influence of waterside turbulence. Despite a relatively large range in the explicitly calculated ocean uptake rate, there is a surprisingly small sensitivity of simulated Marine Boundary Layer ozone concentrations compared to the sensitivity for the commonly applied constant ocean uptake approach. This small sensitivity points at compensating effects through inclusion of the process-based ocean uptake mechanisms to consider variability in oceanic O3 deposition consistent with that in atmospheric and oceanic physical, chemical, and biological processes.

Low-lying baryon spectrum with two dynamical twisted mass fermions

Abstract: The masses of the low-lying baryons are evaluated using two degenerate flavors of twisted mass sea quarks corresponding to pseudoscalar masses in the range of about 270\char21{}500 MeV. The strange valence quark mass is tuned to reproduce the mass of the kaon in the physical limit. The tree-level Symanzik improved gauge action is employed. We use lattices of spatial size 2.1 and 2.7 fm at two values of the lattice spacing with ${r}_{0}/a=5.22(2)$ and ${r}_{0}/a=6.61(3)$. We check for both finite volume and cutoff effects on the baryon masses. We performed a detailed study of the chiral extrapolation of the octet and decuplet masses using SU(2) $\ensuremath{\chi}\mathrm{PT}$. The lattice spacings determined using the nucleon mass at the physical point are consistent with the values extracted using the pion decay constant. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. The baryon masses that we find after taking the continuum limit and extrapolating to the physical limit are in good agreement with experiment.

Homogenization of daily maximum temperature series in the Mediterranean

Abstract: Received 9 December 2008; revised 29 May 2009; accepted 10 June 2009; published 15 August 2009. [1] Homogenization of atmospheric variables to detect and attribute past and present climate trends and to predict scenarios of future meteorological extreme events is a crucial issue for the reliability of analysis results. Here we present a quality control and new homogenization method (PENHOM) based on a penalized log likelihood procedure and a nonlinear model applied to 174 daily summer maximum temperature series in the Greater Mediterranean Region covering the last 50–100 years. The break detection method does not rely on homogeneous reference stations and was chosen owing to the lack of metadata available. The correction procedure allows the higher-order moments of the candidate distribution to be corrected, which is important if the homogenized series are to be used to quantify temperature extremes. Both procedures require a set of highly correlated neighboring stations to correct climate series reliably. After carrying out the homogeneity procedure, 84% of all time series were found to contain at least one artificial breakpoint. Time series of the eastern Mediterranean (one breakpoint in 24 years on average) show significantly more breakpoints than do series of the Western Basin (one breakpoint in 36 years on average). The mean adjustment (standard error) of all daily summer maximum temperatures is +0.03C (±0.38C) for the western Mediterranean, +0.16C (±0.52C) for the central Mediterranean, and +0.19C (±0.30C) for the eastern Mediterranean, indicating a reduced increase in mean summer daytime temperature compared to that detected by analyzing raw data. The adjustments for higher-order moments were not uniform. Most significant mean changes due to homogenization were detected for both: the hottest (+0.15C ± 0.66C) and coldest decile (� 0.83C ± 1.28C) compared to the raw data in the central Mediterranean. This study demonstrates that homogenization of daily temperature data is necessary before any analysis of temperaturerelated extreme events such as heat waves, cold spells, and their impacts on human health, agriculture, and ecosystems can be studied.

The impact of MM5 and WRF meteorology over complex terrain on CHIMERE model calculations

Abstract: . The objective of this study is to evaluate the impact of meteorological input data on calculated gas and aerosol concentrations. We use two different meteorological models (MM5 and WRF) together with the chemistry transport model CHIMERE. We focus on the Po valley area (Italy) for January and June 2005. Firstly we evaluate the meteorological parameters with observations. The analysis shows that the performance of both models in calculating surface parameters is similar, however differences are still observed. Secondly, we analyze the impact of using MM5 and WRF on calculated PM10 and O3 concentrations. In general CHIMERE/MM5 and CHIMERE/WRF underestimate the PMv concentrations for January. The difference in PM10 concentrations for January between CHIMERE/MM5 and CHIMERE/WRF is around a factor 1.6 (PM10 higher for CHIMERE/MM5). This difference and the larger underestimation in PM10 concentrations by CHIMERE/WRF are related to the differences in heat fluxes and the resulting PBL heights calculated by WRF. In general the PBL height by WRF meteorology is a factor 2.8 higher at noon in January than calculated by MM5. This study showed that the difference in microphysics scheme has an impact on the profile of cloud liquid water (CLW) calculated by the meteorological driver and therefore on the production of SO4 aerosol. A sensitivity analysis shows that changing the Noah Land Surface Model (LSM) in our WRF pre-processing for the 5-layer soil temperature model, calculated monthly mean PMv concentrations increase by 30%, due to the change in the heat fluxes and the resulting PBL heights. For June, PM10 calculated concentrations by CHIMERE/MM5 and CHIMERE/WRF are similar and agree with the observations. Calculated O3 values for June are in general overestimated by a factor 1.3 by CHIMERE/MM5 and CHIMERE/WRF. High temporal correlations are found between modeled and observed O3 concentrations.

Epidemiological and clinical characteristics of influenza A(H1N1)v infection in children: The first 45 cases in Cyprus, June - August 2009.

Abstract: Following the first imported case in a tourist in Cyprus on 2 June 2009, the influenza A(H1N1)v virus has spread on the island affecting mainly young adults and children. We describe here the first 45 cases in children. Fever, cough, rhinorrhoea and sore throat were the most common symptoms of infection. Half of the children had fever for one day or only for a few hours. Five children were hospitalised, and overall their symptoms were mild. Adherence to oseltamivir treatment was very high, with low frequency of gastrointestinal side effects such as nausea and vomiting. Camping places and summer schools played a significant role in spreading the infection among children of school age.

Changing Energy Requirements in the Mediterranean Under Changing Climatic Conditions

Abstract: This study investigates the impacts of climate change on energy requirements in the Mediterranean. Energy requirements, especially for space heating and cooling, are closely linked to several weather variables, mainly air temperature. The analysis is based on daily temperature outputs from several regional climate models run at a resolution of 25 km × 25 km in the framework of EU project ENSEMBLES using the A1B emissions scenario. The impacts of changes in temperature on energy requirements are investigated using the concept of degree days, defined as the difference of mean air temperature from a base temperature. Base temperature should be chosen to coincide with the minimum energy consumption. In this way, changes in heating and cooling requirements between the reference and the future period are calculated and areas about to undergo large changes identified. These changes are calculated between a 30-year reference period 1961-1990 and a near future period 2021-2050 taking the ensemble mean of all regional climate models. The near-term future has been chosen instead of the frequently used end-of-the-century period to assist policy makers in their planning. In general, a decrease in energy requirements is projected under future milder winters and an increase under hotter summers.

High-dynamic-range video solution

Abstract: The natural world presents our visual system with a wide, ever-changing range of colors and intensities. Existing video cameras are only capable of capturing a limited part of this wide range with sufficient resolution. High-dynamic-range (HDR) images can represent most of the real world's luminances, but until now capturing HDR images with a linear-response function has been limited to static scenes. This demonstration showcases a novel complete HDR video solution. The system includes a unique HDR video camera capable of capturing a full HDTV video stream consisting of 20 f-stops dynamic range at a resolution of 1920 x 1080 pixels at 30 frames per second; an encoding method for coping with the huge amount of data generated by the camera (achieving a compression ratio of up to 100:1 and real-time decompression); and a new 22-inch desktop HDR display for directly visualizing the dynamic HDR content.

Ultrafast Dynamics of Localized and Delocalized Polaron Transitions in P3HT/PCBM Blend Materials: The Effects of PCBM Concentration

Abstract: Nowadays, organic solar cells have the interest of engineers for manufacturing flexible and low cost devices. The considerable progress of this nanotechnology area presents the possibility of investigating new effects from a fundamental science point of view. In this letter we highlight the influence of the concentration of fullerene molecules on the ultrafast transport properties of charged electrons and polarons in P3HT/PCBM blended materials which are crucial for the development of organic solar cells. Especially, we report on the femtosecond dynamics of localized (P2at 1.45 eV) and delocalized (DP2at 1.76 eV) polaron states of P3HT matrix with the addition of fullerene molecules as well as the free-electron relaxation dynamics of PCBM-related states. Our study shows that as PCBM concentration increases, the amplified exciton dissociation at bulk heterojunctions leads to increased polaron lifetimes. However, the increase in PCBM concentration can be directly related to the localization of polarons, creating thus two competing trends within the material. Our methodology shows that the effect of changes in structure and/or composition can be monitored at the fundamental level toward optimization of device efficiency.

Weakly compressible Poiseuille flows of a Herschel–Bulkley fluid

Abstract: In this work, we derive approximate semi-analytical solutions of the steady, creeping, weakly compressible plane and axisymmetric Poiseuille flows of a Herschel–Bulkley fluid. Since the flow is weakly compressible, the radial velocity component is assumed to be zero and the derivatives of the axial velocity with respect to the axial direction are assumed to be much smaller than those with respect to the radial direction. The axial velocity is then given by an expression similar to that holding for the incompressible flow, the only difference being that the pressure-gradient is a function of the axial coordinate and satisfies a non-linear equation involving the density of the fluid. In the present work, a linear as well as an exponential equation of state, relating the density of the fluid to the pressure, are considered. The pressure distribution along the flow direction is calculated by means of numerical integration and the two-dimensional axial velocity can then be constructed. The effects of compressibility, the equation of state, the Bingham number and the power-law exponent on the solutions are investigated.

Monitoring Charge Exchange in P3HT-Nanotube Composites Using Optical and Electrical Characterisation.

Abstract: Charge exchange at the bulk heterojunctions of composites made by mixing single wall nanotubes (SWNTs) and polymers show potential for use in optoelectronic devices such as solar cells and optical sensors. The density/total area of these heterojunctions is expected to increase with increasing SWNT concentration but the efficiency of solar cell peaks at low SWNT concentrations. Most researchers use current–voltage measurements to determine the evolution of the SWNT percolation network and optical absorption measurements to monitor the spectral response of the composites. However, these methods do not provide a detailed account of carrier transport at the concentrations of interest; i.e., near or below the percolation threshold. In this article, we show that capacitance–voltage (C–V) response of (metal)-(oxide)-(semiconducting composite) devices can be used to fill this gap in studying bulk heterojunctions. In an approach where we combine optical absorption methods withC–V measurements we can acquire a unified optoelectronic response from P3HT-SWNT composites. This methodology can become an important tool for optoelectronic device optimization.

Demonstration of inscription and ablation of phase masks for the production of 1st, 2nd, and 3rd order FBG gratings using a femtosecond laser

Abstract: We present to the best of our knowledge the first example of femtosecond laser inscription/ablation of phase/amplitude masks for the demonstrated purpose of inscribing Bragg gratings in optical fibers. We show that the utilization of a femtosecond laser for the mask production allows for great flexibility in controlling the mask period. The masks are used to produce 1 st , 2 nd and 3 rd order fiber Bragg gratings (FBGs) in SMF-28. The work demonstrates the proof of concept and flexibility for the use of femtosecond lasers for the rapid prototyping of complex and reproducible mask structures. Our inscription studies are augmented by considerations of three-beam interference effects that occur as a result of the strong zeroth-order component that is present in addition to higher-order diffraction components.

Baryon structure from Lattice QCD

Abstract: We present recent lattice results on the baryon spectrum, nucleon electromagnetic and axial form factors, nucleon to Δ transition form factors as well as the Δ electromagnetic form factors. The masses of the low lying baryons and the nucleon form factors are calculated using two degenerate flavors of twisted mass fermions down to pion mass of about 270 MeV. We compare to the results of other collaborations. The nucleon to Δ transition and Δ form factors are calculated in a hybrid scheme, which uses staggered sea quarks and domain wall valence quarks. The dominant magnetic dipole nucleon to Δ transition form factor is also evaluated using dynamical domain wall fermions. The transverse density distributions of the Δ in the infinite momentum frame are extracted using the form factors determined from lattice QCD.

Managing full-text excavation data with semantic tools

Abstract: The paper deals with the management of archaeological data from excavations that cannot be easily processed using traditional forms and relational databases. It proposes a way of preserving the integrity of original information, including spatial relations. It demonstrates that also in this case CIDOC-CRM offers a valid schema that may be easily extended to incorporate geographic elements and relations. The system proposed is applied to a case-study concerning a Bronze Age 10 year-long excavation in Cyprus.

Contemporary Digital Methods for the Geometric Documentation of Churches in Cyprus

Abstract: Recent advances in digital methods incorporating information technology have enabled the traditional surveyor and monument recorder to work faster, more accurately and in an automated way in order to produce advanced digital products, more versatile and more useful to the end users. Such methods include tacheometry, digital photogrammetry, as image-based method, terrestrial laser scanning and the development of specialized software in order to fully exploit the digital data acquisition. Usually, a combination of these methods gives the most efficient cost benefit results, by providing 2D vector and raster products and 3D textured models. In this paper two examples of the implementation of these methods in the geometric documentation of two churches, both significant for the history of Cyprus, are presented. It is concerned with the churches of Virgin Mary (Panayia) Podithou, in Galata and St. George Nikoxylitis in Droushia. The applied methodology, using classical and contemporary techniques of commercial...

Low-lying positive-parity excited states of the nucleon

Abstract: We present an overview of the correlation-matrix methods developed recently by the CSSM Lattice Collaboration for the isolation of excited states of the nucleon. Of particular interest is the first positive-parity excited-state of the nucleon known as the Roper resonance. Using eigenvectors of the correlation matrix we construct parity and eigenstate projected correlation functions which are analysed using standardized methods. The robust nature of this approach for extracting the eigenstate energies is presented. We report the importance of using a variety of source and sink smearings in achieving this. Ultimately the independence of the eigenstate energies from the interpolator basis is demonstrated. In particular we consider $4\times 4$ correlation matrices built from a variety of interpolators and smearing levels. Using FLIC fermions to access the light quark mass regime, we explore the curvature encountered in the energy of the states as the chiral limit is approached. We report a low-lying Roper state contrasting earlier results using correlation matrices. To the best of our knowledge, this is the first time a low-lying Roper resonance has been found using correlation matrix methods. Finally, we present our results in the context of the Roper results reported by other groups.

Nucleon form factors with Nf=2 dynamical twisted mass fermions

Abstract: We present results on the electromagnetic and axial nucleon form factors using two degenerate flavors of twisted mass fermions on lattices of spatial size 2.1 fm and 2.7 fm and a lattice spacing of about 0.09 fm. We consider pion masses in the range of 260-470 MeV. We chirally extrapolate results on the nucleon axial ch arge, the isovector Dirac and Pauli root mean squared radii and magnetic moment to the physical point and co mpare to experiment.

Low-lying positive-parity excited states of the nucleon

Abstract: M. S. Mahbub, Alan ´O Cais, Waseem Kamleh, B.G. Lasscock, Derek B. Leinweber and Anthony G. Williams

A Parallel implementation of a Multi-objective Evolutionary Algorithm

Abstract: Multi-objective Evolutionary Algorithms (MOEAs) have features that can be exploited to harness the processing power offered by modern multi-core CPUs. Modern programming languages offer the ability to use threads and processes in order to achieve parallelism that is inherent in multi-core CPUs. In this paper we present our Parallel implementation of a MOEA algorithm and its application to the de novo drug design problem. The results indicate that using multiple processes that execute independent tasks of a MOEA, can reduce significantly the execution time required and maintain comparable solution quality thereby achieving improved performance.

Optimal graph design using a knowledge-driven multi-objective evolutionary graph algorithm

Abstract: Designing appropriate graphs is a problem frequently occurring in several common applications ranging from designing communication and transportation networks to discovering new drugs. More often than not the graphs to be designed need to satisfy multiple, sometimes conflicting, objectives e.g. total length, cost, complexity or other shape and property limitations. In this paper we present our approach to solving the multi-objective graph design problem and obtaining a set of multiple equivalent compromising solutions. Our method uses multi-objective evolutionary graphs, a graph-specific meta-heuristic optimization method that combines evolutionary algorithms with graph theory and local search techniques exploiting domain-specific knowledge. In the experimental section we present results obtained for the problem of designing molecules satisfying multiple pharmaceutically relevant objectives. The results suggest that the proposed method can provide a variety of valid solutions.

Monitoring coastal water quality in a municipal beach in Paphos-Cyprus using ASTER image data and spectral signatures

Abstract: Using remote sensing data to assess the quality of water bodies has proven to be successful not only in inland waters but to coastal water areas as shown by several others conducted studies. The main objective of this study is to use ASTER data to evaluate the potential of using such remotely sensed digital data, to extract information that help in the monitoring system for Cyprus coastal water quality, especially in municipal beaches that are included in the Blue Flag Programme. Reflectance signature of municipal coastal water is monitored using a GER 1500 field spectroradiometer. Simultaneous measurements of turbidity, temperature have been acquired. E-coli values have been retrieved through the sampling procedure. Such coastal water quality assessment can assist the Blue-Flag Programme in the area under investigation. ASTER images can be programmed for summer acquisitions in which Blue-Flag Programme is active so this can be considered an advantage and can be used by the local authorities as a systematic monitoring tool. It has been found after correlating the SS, Turbidity with the water reflectance obtained using the GER 1500 that high correlation was occurred for the wavelength region that corresponds to ASTER band 2 and band 3 respectively (r 2 >0.80 ). Temporal and spatial variations can be monitored from satellite images as shown from the in-situ validated spectroradiometric measurements.

Delta electromagnetic form factors and quark transverse charge densities from lattice QCD

Abstract: We discuss the techniques to extract the electromagnetic Delta form factors in Lattice QCD. We evaluate these form factors using dynamical fermions with smallest pion mass of about 350 MeV. We pay particular attention to the extraction of the electric quadrupole form factor that signals a deformation of the Delta. The magnetic moment of the $\Delta$ is extrapolated using a chiral effective field theory. Using the form factors we evaluate the transverse density distributions in the infinite momentum frame showing deformation in the Delta.

Steady flow of a two-dimensional liquid curtain under pressure

Abstract: We use finite elements and the full-Newton iteration method to solve the steady, two-dimensional flow of a Newtonian planar film issuing from a slit under a pressure difference, in the presence of gravity and surface tension. The simulated film shapes agree with available experimental data within the range of the experimental error. The numerical calculations show that the shape of the film depends strongly on the imposed pressure difference, inertia and gravity, and is rather insensitive to surface tension.

Omega baryon electromagnetic form factors from lattice QCD

Abstract: We present results on the Omega baryon electromagnetic form factors using N_f= 2 + 1 dynamical domain-wall fermion configurations corresponding to a pion mass of about 330 MeV. We construct appropriate sequential sources for the determination of the two dominant form factors GE0 and GM1 as well as a sequential source that isolates the subdominant electric quadrupole form factor GE2. We calculate the Omega baryon magnetic moment, mu_omega, and electric charge radius, ^2, and compare to experiment, for the case of mu_omega, and to other lattice calculations.