Differences in Airborne Particle and Gaseous Concentrations in Urban Air between Weekdays and Weekends

Airborne particle number concentrations and size distributions as well as CO and NOx concentrations monitored at a site within the central business district of Brisbane, Australia were correlated with the traffic flow rate on a nearby freeway with the aim of investigating differences between weekday and weekend pollutant characteristics. Observations over a 5-year monitoring period showed that the mean number particle concentration on weekdays was (8.8±0.1)×103 cm−3 and on weekends (5.9±0.2)×103 cm−3—a difference of 47%. The corresponding mean particle number median diameters during weekdays and weekends were 44.2±0.3 and 50.2±0.2 nm, respectively. The differences in mean particle number concentration and size between weekdays and weekends were found to be statistically significant at confidence levels of over 99%. During a 1-year period of observation, the mean traffic flow rate on the freeway was 14.2×104 and 9.6×104 vehicles per weekday and weekend day, respectively—a difference of 48%. The mean diurnal variations of the particle number and the gaseous concentrations closely followed the traffic flow rate on both weekdays and weekends (correlation coefficient of 0.86 for particles). The overall conclusion, as to the effect of traffic on concentration levels of pollutant concentration in the vicinity of a major road (about 100 m) carrying traffic of the order of 105 vehicles per day, is that about a 50% increase in traffic flow rate results in similar increases of CO and NOx concentrations and a higher increase of about 70% in particle number concentration

An Analysis of Alternative Maize Marketing Policies in South Africa

The maize-oriented agricultural economies throughout Southern Africa are in fundamental transition. Increased recognition of the costs of historical controls on pricing and marketing already has led to partial maize market liberalization in several countries in the region. However, there is still intense debate over the appropriate scope and implementation of future food market reform. Much of the debate derives from uncertainty over the consequences of comprehensive and politically risky changes to domestic markets, especially at a time when regional market conditions are also in flux due to agricultural restructuring in neighboring countries. There is currently little information on the direction and magnitude of grain trade between South Africa, Zimbabwe, and other countries in the region under a deregulated external trading environment. There is also a lack of information on the regional consequences of alternative domestic maize policy scenarios currently under deliberation in South Africa. The purpose of this research is fourfold. First, we consider the role of food market reform in affecting future economic growth and food security in South Africa, and discuss the congruence between the government's food policy objectives and the existing marketing and pricing system. Second, trends in maize production, trade, prices and marketing costs in South Africa and Zimbabwe, the two largest maize traders in the region, are presented. Third, we present four alternative maize policy scenarios in South Africa, and then estimate their effects on maize production, gross revenues, consumer prices, and trade flows under various weather and pricing scenarios in Zimbabwe. A comparison of results across four policy scenarios clarifies the gainers, losers, and extent of income transfers between various regions and socio-economic groups within each region. The final section identifies means by which national food policy objectives in South Africa may be more cost-effectively achieved through harmonization of policies between South Africa and its regional neighbors.food security, food policy, maize market, Crop Production/Industries, Marketing, Q13,

Das Problem „Siebkrabben“ in der Garnelenfischerei

Along with consumption shrimp, brown shrimp fisheries also land some shrimp too small for human consumption which are sieved out on land and have to be degenerated (“crushed shrimp”). This share is recorded in German official statistics besides a third fraction called “industrial shrimp”. In view of the MSC certification processes, sustainable fishing and the fishermen’s voluntary obligation to - in future - limit the shares of “crushed shrimp”, landings data from 2010 have been analysed. Depending on seasons the goal of less than 20% of “crushed shrimp” in German landings was not met in several months in 2010, especially in August, when more than 40% of the landings contained more than the proposed amount. The processing procedures aboard the vessels are shortly discussed and the proposal is made to rather increase net selectivity than use wider sieves for the cooked fraction before landing. Cooking and processing small and later rejected shrimp is an uneconomic action. Reducing the share of “crushed shrimp” serves the idea of sustainable use of shrimp stocks as well as of sound economics

Embedded crack model: I. Basic formulation

The recently emerged idea of enriching standard nite element interpolations by strain or displacement discontinuities has triggered the development of powerful techniques that allow ecient modelling of regions with highly localized strains, e.g. of fracture zones in concrete, or shear bands in metals or soils. The present paper describes a triangular element with an embedded displacement discontinuity that represents a crack. The constitutive model is formulated within the framework of damage theory, with crack closure eects and friction on the crack faces taken into account. Numerical aspects of the implementation are discussed. In a companion paper, the embedded crack approach is combined with the more traditional smeared crack approach.\u

Digital Signatures for Admittance Control in the Optimized Link State Routing Protocol version 2

Public community Mobile Ad Hoc NETworks (MANETs), such as the ``Funkfeuer'' or ``Freifunk'' networks, scale up to several hundreds of routers, connecting users with each other, and with the Internet. As MANETs are typically operated over wireless channels (e.g. WiFi), access to these networks is granted to anyone in the radio range of another router in the MANET, and running the same MANET routing protocol. In order to protect the stability of the networks from malicious intruders, it is important to ensure that only trusted peers are admitted to participate in the control message exchange, and to provide means for logically ``disconnecting'' a non-trustworthy peer. This memorandum presents the concept of admittance control for the Optimized Link State Routing Protocol version 2 (OLSRv2), and suggests a security extension based on digital signatures. Due to the flexible message format of OLSRv2, this extension keeps compatibility with the core OLSRv2 specification. Several standard digital signature algorithms (RSA, DSA, ECDSA), as well as HMAC, are compared in terms of message overhead and CPU time for generating and processing signatures

Applying the European hydroacoustic standard on fish abundance estimation (EN 15910)

Hydroacoustics is an internationally approved method to study fish for abundance estimates and behaviour to increase our understanding of aquatic ecosystems. In Europe and North- America, the need to compare results between years, lakes and countries has been recognized and as a consequence of this, acoustic methods are being standardized. To study how the European standard Water quality – Guidance on the estimation of fish abundance with mobile hydroacoustic methods (CEN 2014) was perceived by different users, a joint evaluation of the implementation of the standard was performed in 2014 by hydroacoustic experts from three European countries. In some parts of the standard the participants´ actions were different from what was described by the standard, and in some cases methods differed among the participants. A general explanation for most of these cases was that stable equipment performance and experience from discrete surveys reduce the need of controlling actions. We suggest that the results of this study should be considered at the revision of the standard (EN 15910) scheduled for 2017

ENG 3140: The Colonization of the Ipthins

Over the course of the semester, we have read many texts that would have been useful one way or another in our film project. We selected five texts to help us develop the plot of our film: Zahra \u27s Paradise, Toward the African Revolution, Tulip in the Desert, Pyongyang, and Maskarade from Mixed Company. Combining the themes of these works with the traditional hopeful tones of classic Doctor Who episodes, we were able to blend them all together into one believable-though fictitious-universe. When the Doctor arrives to the planet the Humans have colonized, he instantly realizes that something is a little off. As the film develops, he discovers that the Ipthins are taught at a separate school, denied their freedoms, kept from interacting with humans after childhood, and being punished by humans in ways that are illegal. Using his sonic screwdriver and diverse knowledge of colonization, the Doctor is able to help the two races of people put aside their differences and gives them hope that they may have a better, more harmonious future