A poverty dynamics approach to social stratification: The South African case

The wave of upbeat stories on the developing world's emerging middle class has reinvigorated a debate on how social class in general and the middle class in particular ought to be defined and measured. In the economics literature, most scholars agree that being middle class entails being free from poverty, which means being able to afford the basic things in life - not only today, but also tomorrow. In consequence, there is an increasing tendency to define the middle class based on a lack of vulnerability to poverty. In this paper, we strengthen and expand on these existing approaches in three ways: First, we incorporate the differentiation between the middle class and a (non-poor) vulnerable group into a broader social-stratification schema that additionally differentiates between transient and chronic poverty. Second, in estimating the risk of poverty, we employ a multivariate regression model that explicitly allows for possible feedback effects from past poverty experiences and accounts for the potential endogeneity of initial conditions, unobserved heterogeneity, and non-random panel attrition - four factors insufficiently addressed in existing studies. Third, we highlight the value of paying attention to these conceptual and modelling issues by showing that class divisions based on monetary thresholds inadequately capture a household's chances of upward and downward mobility. We then apply our conceptual framework to the South African case. We find that only one in four South Africans can be considered stably middle class or elite. Access to stable labor market income is a key determinant of achieving economic stability. A lack of jobs as well as the prevalence of precarious forms of work drive high levels of vulnerability, which in turn constrains the development of an emergent middle class - not only in South Africa but potentially also in other parts of the developing world that face similar labor market challenges

Prevalence in Primary School Youth of Pica and Rumination Behavior: The Understudied Feeding

Objective: Little epidemiological evidence exists on rumination disorder behavior (RB) and pica behavior (PB). We examined prevalence of RB and PB and presence of comorbid feeding/eating disorder symptoms among school-aged children. Methods: In elementary schools in Switzerland, 1,430 children (54.0% female) ages seven to 13 completed Eating Disorder Examination-Questionnaire for children (ChEDE-Q) and Eating Disturbances in Youth Questionnaire (EDY-Q). Results: EDY-Q data behavior frequency showed 9.7% reported RB only, 10.0% reported PB only, and 3.1% reported RB+PB (≥1 on 0-6 Likert scale). At a clinical cut-off score of ≥4 (at least “often true”), 1.7% had RB only, 3.8% had PB only, and 1.1% had RB+PB. Avoidant/restrictive food intake disorder symptoms were most common in those with RB+PB, and more common in those with RB or PB than those without. Degree of eating disorder symptoms (by ChEDE-Q) over the past 28 days were similar among those with RB, PB, or RB+PB, but less common in those without RB or PB. Discussion: RB and PB were commonly reported in our sample of school-aged children, even at a potential clinically significant cut-off. Our findings also suggest that degree of eating disorder symptom comorbidity is similar between those with RB and PB

Graviton confinement inside hypermonopoles of any dimension

We show the generic existence of metastable massive gravitons in the four-dimensional core of self-gravitating hypermonopoles in any number of infinite-volume extra-dimensions. Confinement is observed for Higgs and gauge bosons couplings of the order unity. Provided these resonances are light enough, they realise the Dvali-Gabadadze-Porrati mechanism by inducing a four-dimensional gravity law on some intermediate length scales. The effective four-dimensional Planck mass is shown to be proportional to a negative power of the graviton mass. As a result, requiring gravity to be four-dimensional on cosmological length scales may solve the mass hierarchy problem.Comment: 23 pages, 6 figures, uses iopart. Misprints corrected, references added, matches published versio

Turbulence changes due to a tidal stream turbine operation in the Pentland Firth (Scotland, UK)

The high tidal stream resource in the Pentland Firth (Scotland, UK) has encouraged the development of commercial scale tidal farms. This work is a modelling study primarily focused on how the layout of arrays determines the extractable power and may affect physical processes in the region. Furthermore, the study provides information about submarine turbine maintenance. Tidal dynamics in the Pentland Firth and Orkney Waters (PFOW) have been reproduced by a three-dimensional FVCOM model implementation. The tidal stream turbines were represented in the model as sub grid scale objects by using a momentum sink approach. It has been explored how different turbine location, number and spacing can allow achieving very different amount of power resource, as well as degree of change to flow velocities. It has also been verified that turbulence changes can lead to an increase in bottom currents in the vicinity of the tidal turbines

Paternal starvation affects metabolic gene expression during zebrafish offspring development and lifelong fitness

Dietary restriction in the form of fasting is a putative key to a healthier and longer life, but these benefits may come at a trade‐off with reproductive fitness and may affect the following generation(s). The potential inter‐ and transgenerational effects of long‐term fasting and starvation are particularly poorly understood in vertebrates when they originate from the paternal line. We utilised the externally fertilising zebrafish amenable to a split‐egg clutch design to explore the male‐specific effects of fasting/starvation on fertility and fitness of offspring independently of maternal contribution. Eighteen days of fasting resulted in reduced fertility in exposed males. While average offspring survival was not affected, we detected increased larval growth rate in F1 offspring from starved males and more malformed embryos at 24 h post‐fertilisation in F2 offspring produced by F1 offspring from starved males. Comparing the transcriptomes of F1 embryos sired by starved and fed fathers revealed robust and reproducible increased expression of muscle composition genes but lower expression of lipid metabolism and lysosome genes in embryos from starved fathers. A large proportion of these genes showed enrichment in the yolk syncytial layer suggesting gene regulatory responses associated with metabolism of nutrients through paternal effects on extra‐embryonic tissues which are loaded with maternal factors. We compared the embryo transcriptomes to published adult transcriptome datasets and found comparable repressive effects of starvation on metabolism‐associated genes. These similarities suggest a physiologically relevant, directed and potentially adaptive response transmitted by the father, independently from the offspring's nutritional state, which was defined by the mother

A single polyploidization event at the origin of the tetraploid genome of Coffea arabica is responsible for the extremely low genetic variation in wild and cultivated germplasm

The genome of the allotetraploid species Coffea arabica L. was sequenced to assemble independently the two component subgenomes (putatively deriving from C. canephora and C. eugenioides) and to perform a genome-wide analysis of the genetic diversity in cultivated coffee germplasm and in wild populations growing in the center of origin of the species. We assembled a total length of 1.536 Gbp, 444 Mb and 527 Mb of which were assigned to the canephora and eugenioides subgenomes, respectively, and predicted 46,562 gene models, 21,254 and 22,888 of which were assigned to the canephora and to the eugeniodes subgenome, respectively. Through a genome-wide SNP genotyping of 736 C. arabica accessions, we analyzed the genetic diversity in the species and its relationship with geographic distribution and historical records. We observed a weak population structure due to low-frequency derived alleles and highly negative values of Taijma's D, suggesting a recent and severe bottleneck, most likely resulting from a single event of polyploidization, not only for the cultivated germplasm but also for the entire species. This conclusion is strongly supported by forward simulations of mutation accumulation. However, PCA revealed a cline of genetic diversity reflecting a west-to-east geographical distribution from the center of origin in East Africa to the Arabian Peninsula. The extremely low levels of variation observed in the species, as a consequence of the polyploidization event, make the exploitation of diversity within the species for breeding purposes less interesting than in most crop species and stress the need for introgression of new variability from the diploid progenitors