Galaxy Cluster Shapes and Systematic Errors in H0 Measured by the Sunyaev-Zel'dovich Effect

Imaging of the Sunyaev-Zel'dovich (SZ) effect in galaxy clusters combined with cluster plasma x-ray diagnostics can measure the cosmic distance scale to high redshift. Projecting the inverse-Compton scattering and x-ray emission along the cluster line-of-sight introduces systematic errors in the Hubble constant, H0, because the true shape of the cluster is not known. I present a study of the systematic errors in the value of H0, as determined by the x-ray and SZ properties of theoretical samples of triaxial isothermal ``beta'' model clusters, caused by projection effects and observer orientation. I calculate estimates for H0 for each cluster based on their large and small apparent angular core radii and their arithmetic mean. I demonstrate that the estimates for H0 for a sample of 25 clusters have 99.7% confidence intervals for the mean estimated H0 analyzing the clusters using either their large or mean angular core radius are within 14% of the ``true'' (assumed) value of H0 (and enclose it), for a triaxial beta model cluster sample possessing a distribution of apparent x-ray cluster ellipticities consistent with that of observed x-ray clusters. This limit on the systematic error in H0 caused by cluster shape assumes that each sample beta model cluster has fixed shape; deviations from constant shape within the clusters may introduce additional uncertainty or bias into this result.Comment: Accepted for publication in the Astrophysical Journal, 24 March 1998; 4 pages, 2 figure

Completeness in Photometric and Spectroscopic Searches for Clusters

We investigate, using simulated galaxy catalogues, the completeness of searches for massive clusters of galaxies in redshift surveys or imaging surveys with photometric redshift estimates, i.e. what fraction of clusters (M>10^14/h Msun) are found in such surveys. We demonstrate that the matched filter method provides an efficient and reliable means of identifying massive clusters even when the redshift estimates are crude. In true redshift surveys the method works extremely well. We demonstrate that it is possible to construct catalogues with high completeness, low contamination and both varying little with redshift.Comment: ApJ in press, 15 pages, 10 figure

Detecting Star Formation in Brightest Cluster Galaxies with GALEX

We present the results of GALEX observations of 17 cool core (CC) clusters of galaxies. We show that GALEX is easily capable of detecting star formation in brightest cluster galaxies (BCGs) out to $z\ge 0.45$ and 50-100 kpc. In most of the CC clusters studied, we find significant UV luminosity excesses and colors that strongly suggest recent and/or current star formation. The BCGs are found to have blue UV colors in the center that become increasingly redder with radius, indicating that the UV signature of star formation is most easily detected in the central regions. Our findings show good agreement between UV star formation rates and estimates based on H$\alpha$ observations. IR observations coupled with our data indicate moderate-to-high dust attenuation. Comparisons between our UV results and the X-ray properties of our sample suggest clear correlations between UV excess, cluster entropy, and central cooling time, confirming that the star formation is directly and incontrovertibly related to the cooling gas.Comment: 39 pages, 11 figures; accepted for publication in The Astrophysical Journal. Figure quality reduced to comply with arXiv file size requirement

Present and future patterns of energy usage in rural areas.

The hypothesis presented in this study is that: "There exists considerable potential for a greater degree of rural energy autonomy, especially through the medium of increasing integration between agricultural/forestry and domestic sectors, to make better use of rural energy resources". This is investigated by two basic lines of inquiry. A study of the future of rural areas and their energy resources and use was carried out, firstly by reference to the available literature, and then by a three round 'Delphi' survey of a panel of 'experts' in rural and energy fields. The results of this survey are presented in the form of a single most likely scenario for a fifty year rural future. The second major constituent of the study is a door-to-door survey of houses and farms in areas of the North-East of Scotland, which investigates current energy use and energy resources for a simplified rural system, as well as attitudes to energy in the future. Current energy use and the energy resource in these rural areas is then projected into the future, by application of the characteristics of the most likely scenario in the 'Delphi' study, to the results of the local survey. The ability to extrapolate the results from these survey areas to the more general British rural environment is also explored

The XMM Cluster Survey: The interplay between the brightest cluster galaxy and the intra-cluster medium via AGN feedback

Using a sample of 123 X-ray clusters and groups drawn from the XMM-Cluster Survey first data release, we investigate the interplay between the brightest cluster galaxy (BCG), its black hole, and the intra-cluster/group medium (ICM). It appears that for groups and clusters with a BCG likely to host significant AGN feedback, gas cooling dominates in those with Tx > 2 keV while AGN feedback dominates below. This may be understood through the sub-unity exponent found in the scaling relation we derive between the BCG mass and cluster mass over the halo mass range 10^13 < M500 < 10^15Msol and the lack of correlation between radio luminosity and cluster mass, such that BCG AGN in groups can have relatively more energetic influence on the ICM. The Lx - Tx relation for systems with the most massive BCGs, or those with BCGs co-located with the peak of the ICM emission, is steeper than that for those with the least massive and most offset, which instead follows self-similarity. This is evidence that a combination of central gas cooling and powerful, well fuelled AGN causes the departure of the ICM from pure gravitational heating, with the steepened relation crossing self-similarity at Tx = 2 keV. Importantly, regardless of their black hole mass, BCGs are more likely to host radio-loud AGN if they are in a massive cluster (Tx > 2 keV) and again co-located with an effective fuel supply of dense, cooling gas. This demonstrates that the most massive black holes appear to know more about their host cluster than they do about their host galaxy. The results lead us to propose a physically motivated, empirical definition of 'cluster' and 'group', delineated at 2 keV.Comment: Accepted for publication in MNRAS - replaced to match corrected proo

The properties of Brightest Cluster Galaxies in the SDSS DR6 adaptive matched filter cluster catalogue

We study the properties of Brightest Cluster Galaxies (BCGs) drawn from a catalogue of more than 69000 clusters in the SDSS DR6 based on the adaptive matched filter technique (AMF, Szabo et al., 2010). Our sample consists of more than 14300 galaxies in the redshift range 0.1-0.3. We test the catalog by showing that it includes well-known BCGs which lie in the SDSS footprint. We characterize the BCGs in terms of r-band luminosities and optical colours as well as their trends with redshift. In particular, we define and study the fraction of blue BCGs, namely those that are likely to be missed by either colour-based cluster surveys and catalogues. Richer clusters tend to have brighter BCGs, however less dominant than in poorer systems. 4-9% of our BCGs are at least 0.3 mag bluer in the g-r colour than the red-sequence at their given redshift. Such a fraction decreases to 1-6% for clusters above a richness of 50, where 3% of the BCGs are 0.5 mag below the red-sequence. A preliminary morphological study suggests that the increase in the blue fraction at lower richnesses may have a non-negligible contribution from spiral galaxies. We show that a colour selection based on the g-r red-sequence or on a cut at colour u-r >2.2 can lead to missing the majority of such blue BCGs. We also extend the colour analysis to the UV range by cross-matching our catalogue with publicly available data from Galex GR4 and GR5. We show a clear correlation between offset from the optical red-sequence and the amount of UV-excess. Finally, we cross-matched our catalogue with the ACCEPT cluster sample (Cavagnolo et al., 2009), and find that blue BCGs tend to be in clusters with low entropy and short cooling times. That is, the blue light is presumably due to recent star formation associated to gas feeding by cooling flows. (abridged)Comment: 15 pages, 15 figures, submitted to MNRA

God and the human condition of suffering

The five papers that follow are set in the context of the problem of, or argument from, evil. I have chosen to discuss, in that context, three topics that are of special interest to me in the hope that what I have to say about them may make a useful contribution to literature on the subject. The topics discussed are, first, the inductive evidential version of the argument from evil considered in light of the subjectivity of human experience; second, the question of attributing blame to God for causing or allowing human suffering; and, third, God’s knowledge of the human condition of suffering. The topic discussed in paper one is the inductive version of the evidential argument from evil, considered in light of the subjectivity of human experiences. I argue that when the latter is taken into account, not only does the evidential problem of evil have less force than might be expected, it also becomes impossible to formulate it in a straightforward way that would be understood and/or accepted by everyone engaged with the problem. Paper two is concerned with James F. Ross’ argument for the illegitimacy of blaming God for the existence of evil even though God has, or shares, responsibility for it. Ross’ contention is that once the relation between God and the created world is understood, it will be clear that God is isolated from, rather than the deserver of, blame. The argument offers a neat and rather ingenious response to those who contend that evil threatens God’s perfect goodness. There can be no such threat, argues Ross. Viewed sympathetically, I try to fill in some of the gaps Ross leaves open in an attempt to see how far the argument may be defended against objections. In the end, however, I give reasons why the theist should not accept it. The subject of paper three is the Free Will Theodicy, which attempts to isolate God from blame for our suffering. Among the conditions necessary for the Theodicy to be effective are (a) that created agents possess the God-given gift of free will to do good and/or cause suffering, and (b) that free will has such a high, positive, and invariant value that God desires us to keep it even if suffering may be the result. If either condition is false, the Theodicy is undermined. I grant (a) but argue against (b) by showing that the value of free will is sensitive to the context in which it is exercised. Specifically, the value can be low or zero, or even negative depending on the context. To argue for this I appeal to our intuitions concerning right and wrong supported by scientific method. The consequence is that the Theodicy is seriously undermined. Set in contexts of the argument from unsurpassability and the argument from evil, in the fourth paper I examine four accounts addressing the question of the kind of world we should expect an unsurpassable being to create, and whether ours is that kind of world. It seems that God must create the best world He can in order to remain unsurpassable and hence free from blame, but is it likely that, given the existence of evil, our world is the best? I examine four accounts that attempt to establish that our world can be regarded as the creation of God. Only one of these argues that God need not create the best. The other accounts try to show that evil is somehow insignificant or non-existent, and ought not to feature in our judgements about the quality of the world. But much depends on one’s point of view. From God’s perspective the world may appear better than it does from ours. No account explains how, given the world’s evils, it is consistent with having been created by God from our point of view. The fifth and final paper addresses the question of whether the God of traditional theism can have knowledge of what it is like for His creatures to experience pain and suffering. I explain why God should have this knowledge, and also why attributing it to Him is problematic. The possibility of doing so depends on how the nature of God and that of ourselves are conceived. I discuss three such conceptions: (a) that God is a spirit and we are physically embodied (the traditional conception); (b) that both God and ourselves are spirits (the idealist conception); and (c) that God is one substance and we are parts of God (the pantheist conception). I argue that it is only according to (c) that the knowledge attribution is plausible. But we are then left with the task of rendering the pantheistic God consistent with what the traditional theist wants to say about Him, and how such a conception is affected by the existence of evil

Anxiety and burnout in young athletes: The mediating role of cognitive appraisal

This study tested the relationship between trait anxiety, cognitive appraisal, and athletes’ burnout proposing two hypotheses: (a) there is a direct relationship between athletes’ trait anxiety and cognitive appraisal and burnout; and (b) cognitive appraisal mediates the relationship between trait anxiety and burnout and this mediation occurs despite the competitive level and sport records of athletes. The study included 673 young athletes and provided measures of trait anxiety, cognitive appraisal, and burnout. Structural equation modelling indicated that cognitive appraisal mediates the relationship between trait anxiety and burnout, confirming hypothesis 2, and this model provided better fit than the direct model of hypothesis 1. However, the mediation also indicated that the direct relationship between trait anxiety and burnout should be considered. The mediating model was invariant according to competitive levels and sport records. In conclusion, cognitive appraisal is an important variable in explaining athletes’ burnout.This study was conducted at Psychology Research Centre (UID/PSI/01662/2013), University of Minho, and supported by the Portuguese Foundation for Science and Technology, the Portuguese Ministry of Science, Technology and Higher Education through national funds and co-financed by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653), and "Guimaraes, European City of Sport 2013".info:eu-repo/semantics/publishedVersio

Field-deployable, quantitative, rapid identification of active Ebola virus infection in unprocessed blood

The West African Ebola virus outbreak underlined the importance of delivering mass diagnostic capability outside the clinical or primary care setting in effectively containing public health emergencies caused by infectious disease. Yet, to date, there is no solution for reliably deploying at the point of need the gold standard diagnostic method, real time quantitative reverse transcription polymerase chain reaction (RT- qPCR), in a laboratory infrastructure-free manner. In this proof of principle work, we demonstrate direct performance of RT-qPCR on fresh blood using far-red fluorophores to resolve fluorogenic signal inhibition and controlled, rapid freeze/thawing to achieve viral genome extraction in a single reaction chamber assay. The resulting process is entirely free of manual or automated sample pre-processing, requires no microfluidics or magnetic/mechanical sample handling and thus utilizes low cost consumables. This enables a fast, laboratory infrastructure-free, minimal risk and simple standard operating procedure suited to frontline, field use. Developing this novel approach on recombinant bacteriophage and recombinant human immunodeficiency virus (HIV; Lentivirus), we demonstrate clinical utility in symptomatic EBOV patient screening using live, infectious Filoviruses and surrogate patient samples. Moreover, we evidence assay co-linearity independent of viral particle structure that may enable viral load quantification through pre-calibration, with no loss of specificity across an 8 log- linear maximum dynamic range. The resulting quantitative rapid identification (QuRapID) molecular diagnostic platform, openly accessible for assay development, meets the requirements of resource- limited countries and provides a fast response solution for mass public health screening against emerging biosecurity threats

Prisoners co-infected with tuberculosis and HIV: a systematic review.

INTRODUCTION: Almost from the beginning of the HIV epidemic in 1981, an association with tuberculosis (TB) was recognized. This association between HIV and TB co-infection has been particularly evident amongst prisoners. However, despite this, few studies of TB in prisons have stratified results by HIV status. Given the high prevalence of HIV-positive persons and TB-infected persons in prisons and the documented risk of TB in those infected with HIV, it is of interest to determine how co-infection varies amongst prison populations worldwide. For this reason we have undertaken a systematic review of studies of co-infected prisoners to determine the incidence and/or prevalence of HIV/TB co-infection in prisons, as well as outcomes in this group, measured as treatment success or death. METHODS: A literature search was undertaken using the online databases PubMed, Embase, IBSS, Scopus, Web of Science, Global Health and CINAHL Plus. No restrictions were set on language or publication date for article retrieval, with articles included if indexed up to 18 October 2015. A total of 1975 non-duplicate papers were identified. For treatment and outcome data all eligible papers were appraised for inclusion; for incidence/prevalence estimates papers published prior to 2000 were excluded from full text review. After full text appraisal, 46 papers were selected for inclusion in the review, 41 for incidence/prevalence estimates and nine for outcomes data, with four papers providing evidence for both outcomes and prevalence/incidence. RESULTS: Very few studies estimated the incidence of TB in HIV positive prisoners, with most simply reporting prevalence of co-infection. Co-infection is rarely explicitly measured, with studies simply reporting HIV status in prisoners with TB, or a cross-sectional survey of TB prevalence amongst prisoners with HIV. Estimates of co-infection prevalence ranged from 2.4 to 73.1% and relative risks for one, given the other, ranged from 2.0 to 10.75, although some studies reported no significant association between HIV and TB. Few studies provided a comparison with the risk of co-infection in the general population. CONCLUSIONS: Prisoners infected with HIV are at high risk of developing TB. However, the magnitude of risk varies between different prisons and countries. There is little evidence on treatment outcomes in co-infected prisoners, and the existing evidence is conflicting in regards to HIV status influence on prisoner treatment outcomes.PROSPERO Number: CRD42016034068