CFD SIMULATIONS OF THE IMPACT OF A LINE VEGETATION ELEMENT ALONG A MOTORWAY ON LOCAL AIR QUALITY

In the paper a CFD-based micro scale air quality model called ENVI-met will be presented. ENVI-met distinguishes itself from other CFD-models due the implementation of a detailed vegetation model which describes the interaction of local vegetation, not only on the wind field, but also on the thermodynamic processes and the diffusion and deposition of gases and particulate matter. This makes the model particularly suitable for a recent research programme initiated by the Air Quality Innovation Project (IPL), founded by the Dutch Ministry for Transport, Public Works and Water Management (Rijkswaterstaat) and the Ministry of Housing, Spatial Planning & the Environment (Ministry of VROM). One of the seven branches of the IPL-project is to investigate both by measurements and modelling the effect of line vegetation along a motorway on local air quality. Recently the model results have been compared to a first measurement campaign

Conjectured Exact Percolation Thresholds of the Fortuin-Kasteleyn Cluster for the +-J Ising Spin Glass Model

The conjectured exact percolation thresholds of the Fortuin-Kasteleyn cluster for the +-J Ising spin glass model are theoretically shown based on a conjecture. It is pointed out that the percolation transition of the Fortuin-Kasteleyn cluster for the spin glass model is related to a dynamical transition for the freezing of spins. The present results are obtained as locations of points on the so-called Nishimori line, which is a special line in the phase diagram. We obtain TFK = 2 / ln [z / (z - 2)] and pFK = z / [2 (z - 1)] for the Bethe lattice, TFK -> infinity and pFK -> 1 / 2 for the infinite-range model, TFK = 2 / ln 3 and pFK = 3 / 4 for the square lattice, TFK ~ 3.9347 and pFK ~ 0.62441 for the simple cubic lattice, TFK ~ 6.191 and pFK ~ 0.5801 for the 4-dimensional hypercubic lattice, and TFK = 2 / ln {[1 + 2 sin (pi / 18)] / [1 - 2 sin (pi / 18) ]} and pFK = [1 + 2 sin (pi / 18) ] / 2 for the triangular lattice, when J / kB = 1, where z is the coordination number, J is the strength of the exchange interaction between spins, kB is the Boltzmann constant, TFK is the temperature at the percolation transition point, and pFK is the probability, that the interaction is ferromagnetic, at the percolation transition point.Comment: 10 pages, 1 figure. v8: this is the final versio

Topological order from quantum loops and nets

I define models of quantum loops and nets which have ground states with topological order. These make possible excited states comprised of deconfined anyons with non-abelian braiding. With the appropriate inner product, these quantum loop models are equivalent to net models whose topological weight involves the chromatic polynomial. A useful consequence is that the models have a quantum self-duality, making it possible to find a simple Hamiltonian preserving the topological order. For the square lattice, this Hamiltonian has only four-spin interactions

Circulating and Adipose Tissue Fatty Acid Composition in Black South African Women with Obesity: A Cross-Sectional Study

Background and Aims: During positive energy balance, excess lipid storage in subcutaneous adipose tissue (SAT) is associated with increased lipolysis. Elevated circulating fatty acid (FA) concentrations from both SAT lipolysis and dietary fat intake may result in visceral adipose tissue (VAT) accumulation, impairment of glucose metabolism, altogether increasing obesity-associated metabolic risks. We aimed to test the hypothesis that FA composition of red blood cell total phospholipids (RBC-TPL) and SAT is associated with body fat centralisation (VAT/SAT ratio) and insulin sensitivity (SI) in black South African women with obesity. Methods: Participants’ (n = 41) body fat composition and distribution, SI, and RBC-TPL, abdominal and gluteal SAT (gSAT) FA composition (gas-liquid chromatography) were measured. Results: RBC-TPL contained higher proportions of saturated fatty acids (SFAs) than SAT (p < 0.001), which were associated with lower SI (p < 0.05). Mono-unsaturated fatty acids (MUFAs) and stearoyl-CoA desaturase-1 (SCD1)-16 were lower, while poly-unsaturated fatty acids (PUFAs), and delta-5 and delta-6 desaturase indices were higher in RBC-TPL than SAT (p < 0.001). Interestingly, FA profiles differed between SAT depots with higher SFAs and lower MUFAs, SCD1-16 and SCD1-18 indices in abdominal compared to gluteal SAT (p < 0.01). In both SAT depots, higher SFAs and lower PUFAs (n-3 and n-6) correlated with lower VAT/SAT ratio; and lower PUFAs (n-3 and n-6) and higher total MUFA correlated with higher SI. Conclusion: Our findings confirm the relationships between the FA composition of RBC-TPL and SAT and metabolic risk in black women with obesity, which are dependent on both the FA class, and the tissue type/blood compartment in which they are distributed

Die probleme wat graad 7 leerders van landelike skole ervaar om aan sport deel neem

Afrikaans language thesis. Abstract in Afrikaans and English.Many learners in rural primary schools do not use the opportunities which exist or which are being created by schools to participate in sport. As learners grow older and proceed through school, a tendency of diminishing numbers of sports participants is being observed. These are not necessarily learners who do not have any talent or sporting ability, they simply do not participate. This study is focused on the reasons and problems why specifically grade seven learners of rural schools do not participate or have dwindling participating numbers. The study does not only focus on participation but also on effective participation. A thorough literature review has revealed that there are mainly three obstacles, namely: interest, embedded constraints and structural obstacles. Research has revealed several problems why learners do not participate in sport or physical activity. This supports the reasons for the diminishing number of participants which was found in the study. The literature also shows that knowledge of sport is needed for effective participation. Questionnaires were used to gather information from grade seven learners, teachers and school principals. The research period was from July to September 2009. The questionnaires were handled personally by the researcher to ensure a consistent approach. The data from the questionnaires were analysed through the use of tables. This study confirmed three main obstacles which were mentioned earlier as the reasons for the diminishing numbers of sport participants. The interest in sport is dwindling because learners indicated that they just don't like sport and that they do not enjoy it. With regard to the embedded constraints learners indicated that they are physically not always able because of a lack of potential and ability. The structural obstacles were the most common factors, such as time constraints, domestic and family responsibilities, finances and transport. Recommendations regarding this study are set out in Chapter Five

Performance of the Vaisala RS80A/H and RS90 Humicap Sensors and the Meteolabor “Snow White” Chilled-Mirror Hygrometer in Paramaribo, Suriname

In climate research there is a strong need for accurate observations of water vapor in the upper atmosphere. Radiosoundings provide relative humidity profiles but the accuracy of many routine instruments is notoriously inadequate in the cold upper troposphere. In this study results from a soundings program executed in Paramaribo, Suriname (5.8°N, 55.2°W), are presented. The aim of this program was to compare the performance of different humidity sensors in the upper troposphere in the Tropics and to test different bias corrections suggested in the literature. The payload of each sounding consisted of a chilled-mirror “Snow White” sensor from Meteolabor AG, which was used as a reference, and two additional sensors from Vaisala, that is, either the RS80A, the RS80H, or the RS90. In total 37 separate soundings were made. For the RS80A a clear, dry bias of between 4% and 8% RH is found in the lower troposphere compared to the Snow White observation, confirming the findings in previous studies. A mean dry bias was found in the upper troposphere, which could be effectively corrected. The RS80H sensor shows a significant wet bias of 2%–5% in RH in the middle and upper troposphere, which has not been reported before. Comparing observations with RS80H sensors of different ages gives no indication of sensor aging or sensor contamination. It is therefore concluded that the plastic cover introduced by Vaisala to avoid sensor contamination is effective. Finally, the RS90 sensor yields a small but significant wet bias of 2%–3% below 7-km altitude. The time-lag error correction from Miloshevich et al. was applied to the Vaisala data, which resulted in an increased variability in the relative humidity profile above 9- (RS80A), 8- (RS80H), and 11-km (RS90) altitude, respectively, which is in better agreement with the Snow White data. The averaged Snow White profile is compared with the average profiles of relative humidity from the European Centre for Medium-Range Weather Forecasts (ECMWF). No significant bias is found in either the analyses or the forecasts. The correlation coefficient for the Snow White and ECMWF data between 200 and 800 hPa was 0.66 for the 36-h forecast and 0.77 for the analysis

Cirrus clouds, humidity, and dehydration in the tropical tropopause layer observed at Paramaribo, Suriname (5.8°N, 55.2°W)

In the framework of the European Project STAR the mobile Aerosol Raman Lidar (MARL) of the Alfred Wegener Institute (AWI) was operated in Paramaribo/Suriname (5.8°, 55.2°W) and carried out extensive observations of tropical cirrus clouds during the fall dry season from September 28 to November 15 2004. With 81% the coverage with ice clouds was very high in the upper troposphere (above 12 km). The frequency of occurrence of subvisible clouds was found to be clearly enhanced compared to the midlatitudes. The extinction-to-backscatter ratio of thin tropical cirrus is with 26 ± 7 sr significantly higher than that of mid-latitude cirrus (16 ± 9 sr).Subvisible cirrus occur mostly in the tropical tropopause layer (TTL) abovean upper tropospheric inversion. The formation conditions of these cloudsand the dehydration of the TTL was investigated by means of a newly developed trajectory model. Clouds were assumed to occur when the relativehumidity above ice (RHI) exceeds 100% due to adiabatic cooling and subsequently the humidity is reduced to the saturation vapor pressure. This simple dehydration scheme yields an amazingly good agreement with cloud andhumidity observations at Paramaribo. However, it challenges the way cirrusformation is generally conceived, since high supersaturation were thoughtto be required. Our results suggest, that the inclination of the TTL to contain solid particles is rather high, even under modestly moist conditions. Wealso detected extremely thin layers of solid particles slightly above the temperature minimum in sub-saturated air which are possibly stabilized by HNO3