African Urbanization as Flight? Some Policy Implications of Geography

The mystery of the lack of a positive relationship between growth and urbanization in sub-Saharan Africa has been raised in a number of studies. A recent paper by Barrios et al. (Journal of Urban Economics 60:357–371, 2006) provides a compelling explanation for why this occurs. Exploiting a new data source, they show how climate change, specifically the reduction in rainfall, has driven people from the increasingly impoverished countryside to the city. They also show that while this is an important factor explaining urbanization in sub-Saharan African countries it does not affect urbanization elsewhere. Their explanation for this important difference is differences in the patterns of rainfall, as well as the composition of soil in most sub-Saharan countries. In a word, geographical factors have dominated the unusual pattern observed in the world’s most rapidly urbanizing continent. In this paper, we extend the work done by Barrios et al. to include more observations and more detailed geographic variables. We first replicate their results and extend the number of observations to more recent periods. Then we consider the effects of a range of specific country geographical characteristics, relying on data developed by other researchers. After discussing our results, we focus on the implications of our findings for policy formulation, particularly for sub-Saharan African countries. The results indicate that geographical circumstances place significantly more important constraints on maximization processes. In other words, urbanization in these countries takes place in a profoundly “second-best” world. We consider what this kind of context implies for the sequencing and implementation of economic reforms which would allow for an urbanization process that would be more conducive to economic growth.     

Exploring relationships among anger, perceived organizational support, and workplace outcomes.

The present study examines anger within a perceived organizational support (POS) theory framework. Using structural equation modeling, the authors explored relationships among POS, anger, and workplace outcomes in a sample of 1,136 employees in 21 stores of a U.S. retail organization. At both individual and store levels, low POS was directly associated with greater anger. At the individual level, anger partially mediated relationships among low POS and turnover intentions, absences, and accidents on the job. Anger had direct and indirect effects on alcohol consumption and health-related risk taking. At the store level, anger had direct negative effects on inventory loss and turnover. The authors interpret these findings in light of social exchange theory and emotion regulation theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in the perceived duration of a narrowband sound induced by a preceding stimulus.

The authors show that a narrowband noise (NBN) is perceived as longer when presented immediately after a wideband noise (WBN), compared to when the WBN is absent. This effect depended on the WBN’s frequency spectrum overlapping that of the NBN, and it increased as the duration of the WBN increased up to 300 ms. It decreased when a silent gap was introduced between the WBN and NBN, but remained significant for an easily detectable gap of 40 ms. A correlate of the effect was observed in the mismatch negativity (MMN) to a deviant stimulus, consisting of a WBN + NBN, presented in a sequence of more common isolated WBNs. The MMN latency was longer for an on-frequency than for an off-frequency WBN; and, more importantly, the size of this difference correlated across participants with the difference in perceived duration. A rhythm-adjustment experiment showed that the presence of an on-frequency WBN immediately preceding a tone caused that tone to be heard as starting earlier than when the WBN was absent. The results are discussed in relation to the continuity illusion and models of duration encoding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

行动研究与绿色计划

介绍针对改善医院,学校及公共建筑等不同的建筑类型的研究,讨论行动研究、基础研究、应用研究这三种研究者与组织机构之间合作的例子,以促进负责任的环境实践.     

Ability of methanolic seed extracts of pawpaw (Asiminatriloba) to inhibit n-3 fatty acid oxidation initiated by peroxyl radicals and reactive oxygen,nitrogen, and sulfur

Methanolic extracts from underripe, ripe, and ripe then dried pawpaw seeds (PPSE) were tested for antioxidative effectiveness. Underripe seeds contained more total phenolic compounds than ripe seeds, but ripe seeds showed the highest reducing potential. PPSE samples effectively scavenged DPPH (>86%). PPSE (0–26.8 μM gallic acid) effectively inhibited lipid oxidation biomarkers in 22:6 phosphatidylcholine (PC) liposome suspensions over 7 day’s incubation at room temperature. PPSE inhibited TBARS in 22:6 PC liposome suspensions induced by peroxyl radical generators, free radical generators that produce reactive oxygen, reactive nitrogen, and reactive sulfur species. After 120 min of storage TBARS inhibition by PPSE was in the order of H₂O₂ ? SIN-1 = DSSO = AAPH ? Sulfite > ONOO = MMb > iron/ascorbate. PPSE inhibited lipid oxidation biomarkers in skeletal muscle homogenates induced by iron/ascorbate. The development of value added products from pawpaw seeds may lead to successful commercialisation of this underutilised fruit.     

Enhanced maternal aggression and associated changes in neuropeptide gene expression in multiparous rats.

Although it has often been speculated that prior reproductive experience improves subsequent maternal care, few studies have examined specific changes in behavior during a 1st versus 2nd lactation. During lactation, mothers display heightened aggression toward male intruders, purportedly to protect vulnerable young. In the current study, maternal aggression was examined in primiparous and age-matched multiparous females on postpartum days 5 (PPD5) and PPD15. Expression of oxytocin, oxytocin receptor, arginine vasopressin, arginine vasopressin V1a receptors, and corticotrophin-releasing hormone mRNA was measured following aggression testing at both time points using real-time quantitative PCR in brain regions previously implicated in the regulation of maternal aggression. Multiparity significantly enhanced maternal aggression on PPD5 but not on PPD15. In addition, this increased aggression was associated with region- and gene-specific changes in mRNA expression. These findings indicate that reproductive experience enhances maternal aggression, an effect that may be mediated by region-specific alterations in neuropeptidergic activity. The adaptations observed in multiparous females provide an innate model for the study of neuroplasticity in the regulation of aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A simple iterative algorithm for parsimonious binary kernel Fisher discrimination

By applying recent results in optimisation theory variously known as optimisation transfer or majorise/minimise algorithms, an algorithm for binary, kernel, Fisher discriminant analysis is introduced that makes use of a non-smooth penalty on the coefficients to provide a parsimonious solution. The problem is converted into a smooth optimisation that can be solved iteratively with no greater overhead than iteratively re-weighted least-squares. The result is simple, easily programmed and is shown to perform, in terms of both accuracy and parsimony, as well as or better than a number of leading machine learning algorithms on two well-studied and substantial benchmarks.     

Comparing the effectiveness of several modeling methods for fault prediction

We compare the effectiveness of four modeling methods—negative binomial regression, recursive partitioning, random forests and Bayesian additive regression trees—for predicting the files likely to contain the most faults for 28 to 35 releases of three large industrial software systems. Predictor variables included lines of code, file age, faults in the previous release, changes in the previous two releases, and programming language. To compare the effectiveness of the different models, we use two metrics—the percent of faults contained in the top 20% of files identified by the model, and a new, more general metric, the fault-percentile-average. The negative binomial regression and random forests models performed significantly better than recursive partitioning and Bayesian additive regression trees, as assessed by either of the metrics. For each of the three systems, the negative binomial and random forests models identified 20% of the files in each release that contained an average of 76% to 94% of the faults.     

A multiplicative model of software defect repair times

We hypothesize that software defect repair times can be characterized by the Laplace Transform of the Lognormal (LTLN) distribution. This hypothesis is rooted in the observation that software defect repair times are influenced by the multiplicative interplay of several factors, and the lognormal distribution is a natural choice to model rates of occurrence of such phenomenon. Conversion of the lognormal rate distribution to an occurrence time distribution yields the LTLN. We analyzed a total of more than 10,000 software defect repair times collected over nine products at Cisco Systems to confirm our LTLN hypothesis. Our results also demonstrate that the LTLN distribution provides a statistically better fit to the observed repair times than either of the two most widely used repair time distributions, namely, the lognormal and the exponential. Moreover, we show that the repair times of subsets of defects, partitioned according to the Orthogonal Defect Classification (ODC) scheme also follow the LTLN distribution. Finally, we describe how the insights that lead to the LTLN repair time model allow us to consider and evaluate alternative process improvement strategies.