Incorporating weather into regionwide safety planning prediction models

Predicting safety on roadways is standard practice for road safety professionals and has a corresponding extensive literature. The majority of safety prediction models are estimated using roadway segment and intersection (microscale) data, while more recently efforts have been undertaken to predict safety at the planning level (macroscale). Safety prediction models typically include roadway, operations, and exposure variables—factors known to affect safety in fundamental ways. Environmental variables, in particular variables attempting to capture the effect of rain on road safety, are difficult to obtain and have rarely been considered. In the few cases weather variables have been included, historical averages rather than actual weather conditions during which crashes are observed have been used. Without the inclusion of weather related variables researchers have had difficulty explaining regional differences in the safety performance of various entities (e.g. intersections, road segments, highways, etc.) As part of the NCHRP 8-44 research effort, researchers developed PLANSAFE, or planning level safety prediction models. These models make use of socio-economic, demographic, and roadway variables for predicting planning level safety. Accounting for regional differences - similar to the experience for microscale safety models - has been problematic during the development of planning level safety prediction models. More specifically, without weather related variables there is an insufficient set of variables for explaining safety differences across regions and states. Furthermore, omitted variable bias resulting from excluding these important variables may adversely impact the coefficients of included variables, thus contributing to difficulty in model interpretation and accuracy. This paper summarizes the results of an effort to include weather related variables, particularly various measures of rainfall, into accident frequency prediction and the prediction of the frequency of fatal and/or injury degree of severity crash models. The purpose of the study was to determine whether these variables do in fact improve overall goodness of fit of the models, whether these variables may explain some or all of observed regional differences, and identifying the estimated effects of rainfall on safety. The models are based on Traffic Analysis Zone level datasets from Michigan, and Pima and Maricopa Counties in Arizona. Numerous rain-related variables were found to be statistically significant, selected rain related variables improved the overall goodness of fit, and inclusion of these variables reduced the portion of the model explained by the constant in the base models without weather variables. Rain tends to diminish safety, as expected, in fairly complex ways, depending on rain frequency and intensity

Water markets an alternative for central water allocation?

South Africa is entering a whole new era in water management. In the face of efforts to curtail runaway government spending and protect the environment, water institutions must foster the conservation and efficient allocation of existing supplies. They must also take water's growing recreational and environmental value into account. The crucial question is, can the current water institutions meet today's requirements? Despite the resulting inefficiency and waste, traditional resource economists continue to identify taxes, regulations, subsidies, and governmental allocation as solutions to today's water problems. Internationally, there is enough evidence to prove that central allocation with almost any resource gave rise to gross inefficiency. The main reason is the distortions on the value placed on resources within such a centralised planning environment. Resources are either valued to high or to low. What is the value of freshwater and how can water be allocated in such a way as to reflect the scarcity value of water? A non-linear spatial equilibrium model was developed to simulate the impact of a potential water market in the Upper-Berg River: Western Cape. This paper explores water markets as an alternative to central water allocation decisionsResource /Energy Economics and Policy,

The impact of trade liberalisation on South African agricultural productivity

This study attempts to examine the empirical relationship between trade and total factor productivity (TFP) in the agricultural sector using both cross -sectiona, (across nine agricultural commodities), and time -series analysis. The Error Correction Model of ordinary least square (OLS) results from the cross -sectional analysis confirm that export shares and capital formation were found to be positive and significant; whereas, import shares and real exchange rate were found to be related negatively. However, the net effect of export and import shares had a positive effect. This implies that trade liberalisation causes productivity gains. Moreover, the time -series analysis goes in the same direction as the cross -sectional results, showing that there is a robust relationship among TFP, degree of openness, and capital formation. Whereas, debt was found to be inversely related, this implies that agricultural industries / farmers lack debt management skills.TFP, OLS, Trade liberalization or degree of openness, capital formation, International Relations/Trade,

Optimisation of different land use regimes in the Mhala district

Communal, commercial and nature conservation land use alternatives occur together at the perimeter of Manyeleti Game Reserve in Mhala district. The different land use alternatives were compared with one another with the purpose of determining the best possible land use. Communal households and the Seville scheme households perform poorly in support of household welfare. This holds disastrous implications for future generations if nothing is done. The Uthla scheme households perform better and generate larger incomes, but at the expense of communal households. Both schemes are highly subsidised by government. Manyeleti Game Reserve is mismanaged and the worst land use alternative in the area, providing no benefit to people living at its perimeter and needs government support for its continued survival. Using multi criteria analysis a combination of communal and conservation land use alternatives is found to be the best alternative, maximising the communities' welfare and conserving the environment.Land Economics/Use,

Recent Trends in Agricultural Land Prices in South Africa: A Preliminary Investigation Using Cointegration Analysis

The main objective of this paper is to report preliminary findings on the recent trends in agricultural land prices in South Africa against the backdrop of growing concerns over their rising levels. Given the important role of land prices, the impact such increases would have on significant national development efforts, including the on-going land reform programme and other aspects of agricultural restructuring, provide strong justification for this investigation. The cointegration approach was employed within a framework that allowed for both long-run and short-run dynamics of the relationships to be identified. Building on previous structural modelling of farmland prices in the country, and using much expanded time series spanning forty-nine years, it was possible to establish some patterns of causation in the relationships between farmland prices and a range of macro-aggregates, including interest rate on debt, the rate of inflation, Gross Domestic Product, among others. Although the important role of foreign buyers is suggested by some of the results, there is need for further studies on this subject, using alternative data sets. The finding of a Granger causality relationship between farmland prices and GDP is interesting to the extent that it reflects buying power and confirms impressions about the crucial role of farmland prices in national economic management and the successful implementation of the on-going agrarian reforms in South Africa.Land Economics/Use, C22, E3, Q15, Q18, Q24,

Mentorship Alliance between South African Farmers: Implication for Sustainable Agriculture Sector Reform

South Africa's agricultural sector is characterized by a skewed participation of the population. There are vastly white commercial farmers and black subsistence farmers. This is attributed to the past government's intervention in the economy, which lead to exclusion of and discrimination against the blacks regarding access to land. The new government is committed to redressing this imbalance through agricultural reform and development strategies namely land, agrarian, trade and market reforms. One of the government's primary policy thrusts is to provide access to agricultural land for people not adequately represented in the agricultural sector. However, the government lacks sufficient resources to provide land and support services to the farmers been settled. This study is motivated by the insights to explore the complementarities of white established commercial farmers on one hand and the black newly emerging farmers' characteristics and the need for a framework within which the stakeholders can contribute to the success of the reforms. The study contributes to the discussion regarding mentorship between these farm types, by addressing an identified knowledge gap with respect to the objective, implementation and reward for mentorship. Mentorship alliance that can transform the South Africa's agricultural sector into a more efficient and competitive sector and enhance the success of South African economic reforms, is conceptualized. The mentorship is expected to be loosely structured, without the complicated legal and contractual processes involved in corporate business alliances. However, it is hoped that the alliance would be a precursor for highly committed joint ventures in the industry.E6, O1, Q15, P0, L12, Agricultural and Food Policy, Farm Management,

INDIRECT EFFECTS OF DIFFERENT AGRICULTURAL TRADE SCENARIOS: A SOUTH AFRICAN CASE STUDY

One of the most important policy measures used by government to influence agricultural production and trade patterns are tariffs. A substantial depreciation in the exchange rate will not be enough to compensate for the negative effects of removing tariffs if the playing field is not level for producers in South Africa. Although the import multiplier show that less inputs will be imported, this saving on foreign exchange is not big enough to outweigh the total impact of imports on the balance of trade. The value-added multiplier clearly indicate that reinvestment and consumer spending (buying power) in agriculture will receive a severe blow. Employment will be reduced, thus increasing the supply of labour into other sectors.International Relations/Trade,

Challenges in the creation of a Southern African sub-regional security community

Conflict and political instability continue to characterise African states and global trends point toward the devolution of the responsibility for conflict management from the United Nations (UN) to regional and sub-regional levels. This poses a significant challenge to sub-regional security arrangements such as the Southern African Development Community Organ for Politics Defence and Security Co-operation (SADC OPDSC). This article resists the temptation to submit to OPDSC-pessimism in view of the failures of the Organ since its inception. Instead it focuses on the immediate short-term challenges as opportunities to be exploited through a partnership between the public and private sector with the active involvement of civil society and the international community. In particular, it emphasises the need for a clear, institutionalised, policy framework that will allow the sub-regional security system to operate (relatively) free from political interference by ruling elites and in the interest of all the citizens of Southern Africa

Assessing individual differences in genome-wide gene expression in human whole blood: reliability over four hours and stability over 10 months.

Studying the causes and correlates of natural variation in gene expression in healthy populations assumes that individual differences in gene expression can be reliably and stably assessed across time. However, this is yet to be established. We examined 4-hour test-retest reliability and 10 month test-retest stability of individual differences in gene expression in ten 12-year-old children. Blood was collected on four occasions: 10 a.m. and 2 p.m. on Day 1 and 10 months later at 10 a.m. and 2 p.m. Total RNA was hybridized to Affymetrix-U133 plus 2.0 arrays. For each probeset, the correlation across individuals between 10 a.m. and 2 p.m. on Day 1 estimates test-retest reliability. We identified 3,414 variable and abundantly expressed probesets whose 4-hour test-retest reliability exceeded .70, a conventionally accepted level of reliability, which we had 80% power to detect. Of the 3,414 reliable probesets, 1,752 were also significantly reliable 10 months later. We assessed the long-term stability of individual differences in gene expression by correlating the average expression level for each probe-set across the two 4-hour assessments on Day 1 with the average level of each probe-set across the two 4-hour assessments 10 months later. 1,291 (73.7%) of the 1,752 probe-sets that reliably detected individual differences across 4 hours on two occasions, 10 months apart, also stably detected individual differences across 10 months. Heritability, as estimated from the MZ twin intraclass correlations, is twice as high for the 1,752 reliable probesets versus all present probesets on the array (0.68 vs 0.34), and is even higher (0.76) for the 1,291 reliable probesets that are also stable across 10 months. The 1,291 probesets that reliably detect individual differences from a single peripheral blood collection and stably detect individual differences over 10 months are promising targets for research on the causes (e.g., eQTLs) and correlates (e.g., psychopathology) of individual differences in gene expression