Levels of poverty and the poverty gap in rural Limpopo

Purpose/objectives: The aim of this paper is to obtain a better understanding of the income and expenditure patterns of selected deep rural villages. This is done by measuring the level of poverty and/or the poverty gap of 132 households in Limpopo, one of the poorest provinces in South Africa. Problem investigated: The Millennium Declaration symbolises the commitment to end extreme poverty, but limited data is available for rural areas to inform policy decisions. The relative income shares for individuals, households and percentile groups within a population provide the best information on poverty for policy formulation. The nature and size distribution of income are therefore central to analysing the poverty problem within low-income areas. The survey area is one of the poorest areas in South Africa, and shows what data is needed to measure and understand the extent of poverty. Design/Method/Approach: A representative sample of 132 households was drawn, which represents 6,9 percent of the estimated 1900 households in selected villages of rural Limpopo. A total of 740 household members were represented in the survey, with an average of 5,6 members per household. Originality/Value: Although this is a relatively small sample, it generated much-needed data on this very poor area of South Africa. Detailed empirical data on the income and expenditure patterns is not available, especially for rural areas. The socio-economic data from this research supported an important health project of the Water and Health Research Unit (WHRU) of the University of Johannesburg. The article also lays the foundation for further research in this field of study, facilitating engagement with a number of related debates such as those about satisfaction of life, vulnerability to poverty, the geography of deprivation and the mapping of poverty. Conclusion: The main finding is that the government provides for many needs of the poor, especially in the deep rural areas. Only 18 percent of the sample households did not receive a state grant in 2007. This was an injection of R88 800 or 33,4 percent of the total income per month, which excludes the social wage in terms of free basic water, electricity, subsidised or free housing, health care subsidies and other support to poor people and rural communities. Of the 485 non-economically active people in the sample, more than 364 or 75 percent receive an income, mainly in the form of state grants. Education suggests itself as a route out of poverty, rather than the child grant and other subsidies that encourage poor people to have more children. Poor couples and single-member households fall through the safety net, because they do not qualify for state grants and have no children yet

The Proper Motion of Sgr A*: II. The Mass of Sgr A*

We report measurements with the VLBA of the position of Sgr A* with respect to two extragalactic radio sources over a period of eight years. The apparent proper motion of \sgrab relative to J1745-283 is 6.379 +/- 0.024 mas/y along a position angle of 209.60 +/- 0.18 degrees, almost entirely in the plane of the Galaxy. The effects of the orbit of the Sun around the Galactic center can account for this motion, and the residual proper motion of Sgr A* perpendicular to the plane of the Galaxy is -0.4 +/- 0.9 km/s. A maximum-likelihood analysis of the motion expected for a massive object within the observed Galactic center stellar cluster indicates that Sgr A* contains more than about 10% of the approximately 4 x 10^6 Msun deduced from stellar orbits. The intrinsic size of Sgr A*, as measured by several investigators, is less than 1 AU, and the implied mass density of ~10^22 Msun/pc^3 is within about three orders of magnitude of a comparable super-massive black hole within its Schwarzschild radius. Our observations provide the first direct evidence that a compact radiative source at the center of a galaxy contains of order 10^6 Msun and provides overwhelming evidence that it is in the form of a super-massive black hole. Finally, the existence of "intermediate mass" black holes more massive than ~10^4 Msun between roughly 10^3 and 10^5 AU from Sgr A* are excluded.Comment: 37 pages, 8 figures, 4 table

Exploring the emotional dynamics of subclinically depressed individuals with and without anhedonia:An experience sampling study

Background: Anhedonia has been linked to worse prognosis of depression. The present study aimed to construct personalized models to elucidate the emotional dynamics of subclinically depressed individuals with versus without symptoms of anhedonia. Methods: Matched subclinically depressed individuals with and without symptoms of anhedonia (N = 40) of the HowNutsAreTheDutch sample completed three experience sampling methodology assessments per day for 30 days. For each individual, the impact of physical activity, stress experience, and high/low arousal PA/NA on each other was estimated through automated impulse response function analysis (IRF). These individual IRF associations were combined to compare anhedonic versus non-anhedonic individuals. Results: Physical activity had low impact on affect in both groups. In non-anhedonic individuals, stress experience increased NA and decreased PA and physical activity more strongly. In anhedonic individuals, PA high arousal showed a diminished favorable impact on affect (increasing NA/stress experience, decreasing PA/physical activity). Finally, large heterogeneity in the personalized models of emotional dynamics were found. Limitations: Stress experience was measured indirectly by assessing level of distress; the timeframe in between measurements was relatively long with 6 h; and only information on one of the two hallmarks of anhedonia, loss of interest, was gathered. Conclusions: Our results suggest different pathways of emotional dynamics underlie depressive symptomatology. Subclinically depressed individuals with anhedonic complaints are more strongly characterized by diminished favorable impact of PA high arousal and heightened NA reactivity, whereas subclinically depressed individuals without these anhedonic complaints seem more characterized by heightened stress reactivity. The automatically generated personalized models may offer patient-specific insights in emotional dynamics, which may show clinical relevance

Black hole mergers in the universe

Mergers of black-hole binaries are expected to release large amounts of energy in the form of gravitational radiation. However, binary evolution models predict merger rates too low to be of observational interest. In this paper we explore the possibility that black holes become members of close binaries via dynamical interactions with other stars in dense stellar systems. In star clusters, black holes become the most massive objects within a few tens of millions of years; dynamical relaxation then causes them to sink to the cluster core, where they form binaries. These black-hole binaries become more tightly bound by superelastic encounters with other cluster members, and are ultimately ejected from the cluster. The majority of escaping black-hole binaries have orbital periods short enough and eccentricities high enough that the emission of gravitational radiation causes them to coalesce within a few billion years. We predict a black-hole merger rate of about $1.6 \times 10^{-7}$ per year per cubic megaparsec, implying gravity wave detection rates substantially greater than the corresponding rates from neutron star mergers. For the first generation Laser Interferometer Gravitational-Wave Observatory (LIGO-I), we expect about one detection during the first two years of operation. For its successor LIGO-II, the rate rises to roughly one detection per day. The uncertainties in these numbers are large. Event rates may drop by about an order of magnitude if the most massive clusters eject their black hole binaries early in their evolution.Comment: 12 pages, ApJL in pres

OB Stars in the Solar Neighborhood I: Analysis of their Spatial Distribution

We present a newly-developed, three-dimensional spatial classification method, designed to analyze the spatial distribution of early type stars within the 1 kpc sphere around the Sun. We propose a distribution model formed by two intersecting disks -the Gould Belt (GB) and the Local Galactic Disk (LGD)- defined by their fundamental geometric parameters. Then, using a sample of about 550 stars of spectral types earlier than B6 and luminosity classes between III and V, with precise photometric distances of less than 1 kpc, we estimate for some spectral groups the parameters of our model, as well as single membership probabilities of GB and LGD stars, thus drawing a picture of the spatial distribution of young stars in the vicinity of the Sun.Comment: 28 pages including 9 Postscript figures, one of them in color. Accepted for publication in The Astronomical Journal, 30 January 200

Asymmetric supernova in hierarchical multiple star systems and application to J1903+0327

We develop a method to analyze the effect of an asymmetric supernova on hierarchical multiple star systems and we present analytical formulas to calculate orbital parameters for surviving binaries or hierarchical triples and runaway velocities for their dissociating equivalents. The effect of an asymmetric supernova on the orbital parameters of a binary system has been studied to great extent (e.g. Hills 1983; Kalogera 1996; Tauris & Takens 1998), but this effect on higher multiplicity hierarchical systems has not been explored before. With our method, the supernova effect can be computed by reducing the hierarchical multiple to an effective binary by means of recursively replacing the inner binary by an effective star at the center of mass of that binary. We apply our method to a hierarchical triple system similar to the progenitor of PSR J1903+0327 suggested by Portegies Zwart et al. (2011). We confirm their earlier finding that PSR J1903+0327 could have evolved from a hierarchical triple that became unstable and ejected the secondary star of the inner binary. Furthermore, if such as system did evolve via this mechanism the most probable configuration would be a small supernova kick velocity, an inner binary with a large semi-major axis, and the fraction of mass accreted onto the neutron star to the mass lost by the secondary would most likely be between 0.35 and 0.5Comment: 13 pages, 9 figures, accepted for publication in MNRA

A Spectroscopic Study of Field and Runaway OB Stars

Identifying binaries among runaway O- and B-type stars offers valuable insight into the evolution of open clusters and close binary stars. Here we present a spectroscopic investigation of 12 known or suspected binaries among field and runaway OB stars. We find new orbital solutions for five single-lined spectroscopic binaries (HD 1976, HD 14633, HD 15137, HD 37737, and HD 52533), and we classify two stars thought to be binaries (HD 30614 and HD 188001) as single stars. In addition, we reinvestigate their runaway status using our new radial velocity data with the UCAC2 proper motion catalogs. Seven stars in our study appear to have been ejected from their birthplaces, and at least three of these runaways are spectroscopic binaries and are of great interest for future study.Comment: 21 pages, 1 figure, 7 tables; Accepted to Ap