Could multiple voids explain the Cosmic Microwave Background Cold Spot anomaly?

Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) is an outstanding problem. Explanations vary from assuming it is just a > 3 sigma primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the cosmic web. Two structure configurations are considered. The first, through simulations of 20 voids, produces a central mean temperature of ~-50 mu K. In this model the central CS temperature lies at ~ 2 sigma but fails to explain the CS hot ring. An alternative multi-void model (using more pronounced compensated voids) produces much smaller temperature profiles, but contains a prominent hot ring. Arrangements containing closely placed voids at low redshift are found to be particularly well suited to produce CS-like profiles. We then measure the significance of the CS if CS-like profiles (which are fitted to the ISW+RS of multi-void scenarios) are removed. The CS tension with the LCDM model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.Comment: 5 pages, 3 figures, as appears in MNRAS Letter

The cosmic microwave background Cold Spot anomaly: the impact of sky masking and the expected contribution from the Integrated Sachs-Wolfe effect

We re-analyse the cosmic microwave background (CMB) Cold Spot (CS) anomaly with particular focus on understanding the bias a mask (contaminated by Galactic and point sources) may introduce. We measure the coldest spot, found by applying the Spherical Mexican Hat Wavelet transform on 100 000 cut-sky (masked) and full-sky CMB simulated maps. The CS itself is barely affected by the mask; we estimate a 94 per cent probability that the CS is the full-sky temperature minimum. However, approximately 48 per cent (masked fraction of the mask) of full-sky minima are obscured by the mask. Since the observed minima are slightly hotter than the full-sky ensemble of minima, a cut-sky analysis would have found the CS to be significant at approximately 2.2 sigma with a wavelet angular scale of R = 5 degrees. None the less, comparisons to full-sky minima show the CS significance to be only approximately 1.9 sigma and less than 2 sigma for all R. The CS on the last scattering surface may be hotter due to the integrated Sachs-Wolfe effect in the line of sight. However, our simulations show that this on average only approximately 10 per cent (about 10 micro K but consistent with zero) of the CS temperature profile. This is consistent with Lambda and cold dark matter reconstructions of this effect based on observed line-of-sight voids.Comment: 6 pages, 5 figures, changes made to match version published in MNRA

Stakeholder perceptions of the selection of management staff at public schools in the Pinetown district.

Thesis (M.Ed.) - University of KwaZulu-Natal, 2006.There has been a significant number of disputes being declared after every selection process each year since 1998 when School Governing Bodies were given the responsibility of selecting management staff at schools (Thurlow 2003). Also, anecdotal evidence is that there is suspicion amongst educators that unfairness and favoritism in the selection of management staff is rife. Hence, the researcher sought to develop better understanding of how the selection policy is perceived to be problematic in its implementation. With this in mind the researcher examined the perception of stakeholders, namely educators and School Governing Bodies, on the selection of management staff at public schools in a suburb in the Pinetown District. The research involved all eight schools in the Suburb which comprised two secondary schools and six primary schools. All the teachers and management staff and chairpersons of the Selection Committees of the School Governing Bodies in these schools were targeted for the study. The research instruments used for this study were questionnaires that were administered on educators and interviews conducted with the chairpersons of the Selection Committees of the Schools' Governing Bodies. The findings revealed that both the educators and School Governing Bodies were disillusioned with the current selection process. While the chairpersons of the Selection Committees expressed their dissatisfaction at the training proffered by the Department of Education, the educators indicated frustration at not being promoted and perceived the selection to be unfair and based on favoritism and nepotism. Educators also felt very ABSTRACT There has been a significant number of disputes being declared after every selection process each year since 1998 when School Governing Bodies were given the responsibility of selecting management staff at schools (Thurlow 2003). Also, anecdotal evidence is that there is suspicion amongst educators that unfairness and favoritism in the selection of management staff is rife. Hence, the researcher sought to develop better understanding of how the selection policy is perceived to be problematic in its implementation. With this in mind the researcher examined the perception of stakeholders, namely educators and School Governing Bodies, on the selection of management staff at public schools in a suburb in the Pinetown District. The research involved all eight schools in the Suburb which comprised two secondary schools and six primary schools. All the teachers and management staff and chairpersons of the Selection Committees of the School Governing Bodies in these schools were targeted for the study. The research instruments used for this study were questiormaires that were administered on educators and interviews conducted with the chairpersons of the Selection Committees of the Schools' Governing Bodies. The findings revealed that both the educators and School Governing Bodies were disillusioned with the current selection process. While the chairpersons of the Selection Committees expressed their dissatisfaction at the training proffered by the Department of Education, the educators indicated frustration at not being promoted and perceived the selection to be unfair and based on favoritism and nepotism. Educators also felt very strongly that the Selection Committees were not following procedures as legislated. The findings also revealed that both sets of stakeholders felt that the Department of Education _ should take sole responsibility for selecting management staff for schools if the perceived shortcomings are to be overcome. Recommendations emanating from the above include shifting the responsibility for the selection ofmanagement staff from that of School Governing Bodies to the Department ofEducation, co-opting department officials into the Selection Committees for their knowledge and expertise, enhancing training and capacity building programs for Selection Committees and the provisioning of counseling for unsuccessful applicants. 11 strongly that the Selection Committees were not following procedures as legislated. The findings also revealed that both sets of stakeholders felt that the Department of Education .. should take sole responsibility for selecting management staff for schools if the perceived shortcomings are to be overcome. Recommendations emanating from the above include shifting the responsibility for the selection of management staff from that of School Governing Bodies to the Department of Education, co-opting department officials into the Selection Committees for their knowledge and expertise, enhancing training and capacity building programs for Selection Committees and the provisioning of counseling for unsuccessful applicants

Cosmology and neutrino mass with the minimum spanning tree

The information content of the minimum spanning tree (MST), used to capture higher order statistics and information from the cosmic web, is compared to that of the power spectrum for a CDM model. The measurements are made in redshift space using haloes from the Quijote simulation of mass ≥ 3.2× 1013, h-1,M⊙ in a box of length Lbox=1h-1, Gpc. The power spectrum multipoles (monopole and quadrupole) are computed for Fourier modes in the range 0.006, hMpc-1< k < 0.5, hMpc-1. For comparison the MST is measured with a minimum length-scale of lmin≃13, h-1, Mpc. Combining the MST and power spectrum allows for many of the individual degeneracies to be broken; on its own the MST provides tighter constraints on the sum of neutrino masses Mν and cosmological parameters h, ns, an

New rules for security and survival: Southern Africa's adaptation to a changing world environment

In the wake of the post-Cold War era, students of international relations were forced to review their theoretical frameworks to explain new rules for international peace and security. States are now confronted with new constraints for their security and survival as current trends in international politics depict a 'regionalisation' of peace and security. For southern Africa, likewise, the end of the Cold War and, moreover, apartheid, compels its member states to redefine their security strategies and mechanisms for survival. This thesis undertakes to examine southern Africa's adaptation to new rules of a changing world environment, to ensure a stable and secure region, into the next millennium. At the outset of this thesis lies a conceptual contextualisation of security within the major contemporary theoretical approaches of international relations. By examining the essential differences between the redefinitions and new conceptualisations of security, this thesis, firstly argues that the state in southern Africa must be retained as a primary referent of security. This argument is premised on the need to create stronger states for a 'regionalisation' of security in southern Africa. The second issue examined is the changing world environment and its impact on the state and development in Africa, as the new constraints to which the continent must adapt, for security and survival. Arguing that the new international economic order and 'globalisation' dictate the new rules, this chapter asserts that the 'weak' states in Africa need to be strengthened to have the necessary capacity to be the means for its people's security. Finally this thesis examines the new rules for southern Africa's adaptation to a changing world environment. The new rules for the African sub-continent involve the formation of a security regime and economic community with, the power-house, South Africa. Using the Southern African Development Community(SADC) as the umbrella body, the formation of the Organ for Politics, Defence and Security, and signing of trade protocols for a movement towards a free trade area, are evidence of southern Africa's attempts to adapt to new rules for its security. Such adaptation cannot, however, be accomplished with 'weak' states. Southern African states will have to, therefore, be strengthened to attain a more secure adaptation to the new international (economic) order

Full sky Integrated Sachs-Wolfe maps for the MICE Grand Challenge lightcone simulation

We present full-sky maps of the Integrated Sachs-Wolfe effect (ISW) for the MICE Grand Challenge lightcone simulation up to redshift 1.4. The maps are constructed in the linear regime using spherical Bessel transforms. We compare and contrast this procedure against analytical approximations found in the literature. By computing the ISW in the linear regime we remove the substantial computing and storage resources required to calculate the non-linear Rees-Sciama effect. Since the linear ISW is $~10^{2}\times$ larger in $\Delta T/T$ this has a neglegible impact on the maps produced and only becomes relevant on scales which are dominated by cosmic microwave background (CMB) anisotropies. The MICE simulation products have been extensively used for studies involving current and future galaxy surveys. The availability of these maps will allow MICE to be used for future galaxy and CMB cross-correlation studies, ISW reconstruction studies and ISW void-stacking studies probed by galaxy surveys such as DES, DESI, Euclid and Rubin LSST. The pipeline developed in this study is provided as a public Python package pyGenISW. This could be used in future studies for constructing the ISW from existing and future simulation suites probing vast sets of cosmological parameters and models.Comment: 11 pages, 6 figures, to be submitted to Monthly Notices of the Royal Astronomical Society. The analysis presented in this paper was calculated using pyGenISW which is available here: https://github.com/knaidoo29/pyGenIS

Understanding the Processes of Translation and Transliteration in Qualitative Research

There has been growing interest in the use of qualitative methods in health research amongst health and social care professionals. Good qualitative cross-cultural research analysis is not an easy task as it involves knowledge of different approaches, techniques and command of the appropriate languages. This article aims to discuss and explore some of the key processes and concepts involved in conducting translation and transliteration of qualitative research

A dark matter solution to the H0H_{0} and σ8\sigma_{8} tensions, and the integrated Sachs-Wolfe void anomaly

We consider a phenomenological model of dark matter with an equation-of-state that is negative and changing at late times. We show this couples the $H_{0}$ and $\sigma_{8}$ tensions, providing an explanation for both simultaneously, while also providing an explanation for the anomalously large integrated Sachs-Wolfe (ISW) effect from cosmic voids. Observations of high ISW from cosmic voids may therefore be evidence that dark matter plays a significant role in the $H_{0}$ and $\sigma_{8}$ tensions. We predict the ISW from cosmic voids to be a factor of ~ 2 greater in this model than what is expected from the standard model $\Lambda$CDM.Comment: 5 pages (+references) and 3 figures. Comments welcom

Beyond two-point statistics: using the minimum spanning tree as a tool for cosmology

Cosmological studies of large-scale structure have relied on two-point statistics, not fully exploiting the rich structure of the cosmic web. In this paper we show how to capture some of this cosmic web information by using the minimum spanning tree (MST), for the first time using it to estimate cosmological parameters in simulations. Discrete tracers of dark matter such as galaxies, N-body particles or haloes are used as nodes to construct a unique graph, the MST, that traces skeletal structure. We study the dependence of the MST on cosmological parameters using haloes from a suite of COmoving Lagrangian Acceleration (COLA) simulations with a box size of 250 h(-1) Mpc, varying the amplitude of scalar fluctuations (A(s)), matter density (Omega(m)), and neutrino mass (Sigma m(nu)). The power spectrum P and bispectrum B are measured for wavenumbers between 0.125 and 0.5 h Mpc(-1), while a corresponding lower cut of similar to 12.6 h(-1) Mpc is applied to the MST. The constraints from the individual methods are fairly similar but when combined we see improved 1 sigma constraints of similar to 17 per cent (similar to 12 per cent) on Omega(m) and similar to 12 per cent (similar to 10 per cent) on A(s) with respect to P (P + B) thus showing the MST is providing additional information. The MST can be applied to current and future spectroscopic surveys (BOSS, DESI, Euclid, PSF, WFIRST, and 4MOST) in 3D and photometric surveys (DES and LSST) in tomographic shells to constrain parameters and/or test systematics

The Dark Energy Survey : more than dark energy – an overview

This overview paper describes the legacy prospect and discovery potential of the Dark Energy Survey (DES) beyond cosmological studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4 m Blanco Telescope in Chile to image 5000 sq deg of the sky in five filters (grizY). By its completion, the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of Type Ia supernovae and other transients. The main goals of DES are to characterize dark energy and dark matter, and to test alternative models of gravity; these goals will be pursued by studying large-scale structure, cluster counts, weak gravitational lensing and Type Ia supernovae. However, DES also provides a rich data set which allows us to study many other aspects of astrophysics. In this paper, we focus on additional science with DES, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrates, using early data (from ‘Science Verification’, and from the first, second and third seasons of observations), what DES can tell us about the Solar system, the Milky Way, galaxy evolution, quasars and other topics. In addition, we show that if the cosmological model is assumed to be +cold dark matter, then important astrophysics can be deduced from the primary DES probes. Highlights from DES early data include the discovery of 34 trans-Neptunian objects, 17 dwarf satellites of the Milky Way, one published z > 6 quasar (and more confirmed) and two published superluminous supernovae (and more confirmed)