An infrared survey of brightest cluster galaxies: Paper I

We report on an imaging survey with the Spitzer Space Telescope of 62 brightest cluster galaxies with optical line emission. These galaxies are located in the cores of X-ray luminous clusters selected from the ROSAT All-Sky Survey. We find that about half of these sources have a sign of excess infrared emission; 22 objects out of 62 are detected at 70 microns, 18 have 8 to 5.8 micron flux ratios above 1.0 and 28 have 24 to 8 micron flux ratios above 1.0. Altogether 35 of 62 objects in our survey exhibit at least one of these signs of infrared excess. Four galaxies with infrared excesses have a 4.5/3.6 micron flux ratio indicating the presence of hot dust, and/or an unresolved nucleus at 8 microns. Three of these have high measured [OIII](5007A)/Hbeta flux ratios suggesting that these four, Abell 1068, Abell 2146, and Zwicky 2089, and R0821+07, host dusty active galactic nuclei (AGNs). 9 objects (including the four hosting dusty AGNs) have infrared luminosities greater than 10^11 L_sol and so can be classified as luminous infrared galaxies (LIRGs). Excluding the four systems hosting dusty AGNs, the excess mid-infrared emission in the remaining brightest cluster galaxies is likely related to star formation.Comment: accepted for publication in ApJ

Constraints on UV Absorption in the Intracluster Medium of Abell 1030

We present results from an extensive HST spectroscopic search for UV absorption lines in the spectrum of the quasar B2~1028+313, which is associated with the central dominant galaxy in the cluster Abell~1030 ($z=0.178$). This is one of the brightest known UV continuum sources located in a cluster, and therefore provides an ideal opportunity to obtain stringent constraints on the column densities of any cool absorbing gas that may be associated with the intracluster medium (ICM). Our HST spectra were obtained with the FOS and GHRS, and provide continuous coverage at rest-frame wavelengths from $\sim 975$ to 4060~\AA, thereby allowing the investigation of many different elements and ionization levels. We utilize a new technique that involves simultaneous fitting of large numbers of different transitions for each species, thereby yielding more robust constraints on column densities than can be obtained from a single transition. This method yields upper limits of $\lesssim 10^{11} - 10^{13}$ cm$^{-2}$ on the column densities of a wide range of molecular, atomic and ionized species that may be associated with the ICM. We also discuss a possible \Lya and C IV absorption system associated with the quasar. We discuss the implications of the upper limits on cool intracluster gas in the context of the physical properties of the ICM and its relationship to the quasar.Comment: Astrophysical Journal, in press, 19 pages, includes 5 PostScript figures. Latex format, uses aas2pp4.sty and epsfig.sty file

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 C4 Clustering Algorithm: Clusters of Galaxies in the Sloan Digital Sky Survey

We present the "C4 Cluster Catalog", a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2) of the Sloan Digital Sky Survey (SDSS). The C4 cluster--finding algorithm identifies clusters as overdensities in a seven-dimensional position and color space, thus minimizing projection effects which plagued previous optical clusters selection. The present C4 catalog covers ~2600 square degrees of sky with groups containing 10 members to massive clusters having over 200 cluster members with redshifts. We provide cluster properties like sky location, mean redshift, galaxy membership, summed r--band optical luminosity (L_r), velocity dispersion, and measures of substructure. We use new mock galaxy catalogs to investigate the sensitivity to the various algorithm parameters, as well as to quantify purity and completeness. These mock catalogs indicate that the C4 catalog is ~90% complete and 95% pure above M_200 = 1x10^14 solar masses and within 0.03 <=z <= 0.12. The C4 algorithm finds 98% of X-ray identified clusters and 90% of Abell clusters within 0.03 <= z <= 0.12. We show that the L_r of a cluster is a more robust estimator of the halo mass (M_200) than the line-of-sight velocity dispersion or the richness of the cluster. L_r. The final SDSS data will provide ~2500 C4 clusters and will represent one of the largest and most homogeneous samples of local clusters.Comment: 32 pages of figures and text accepted in AJ. Electronic version with additional tables, links, and figures is available at http://www.ctio.noao.edu/~chrism/c

The Extended Blue Continuum and Line Emission around the Central Radio Galaxy in Abell 2597

We present results from detailed imaging of the centrally dominant radio elliptical galaxy in the cooling flow cluster Abell 2597, using data obtained with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). This object is one of the archetypal "blue-lobed" cooling flow radio elliptical galaxies, also displaying a luminous emission-line nebula, a compact radio source, and a significant dust lane and evidence of molecular gas in its center. We show that the radio source is surrounded by a complex network of emission-line filaments, some of which display a close spatial association with the outer boundary of the radio lobes. We present a detailed analysis of the physical properties of ionized and neutral gas associated with the radio lobes, and show that their properties are strongly suggestive of direct interactions between the radio plasma and ambient gas. We resolve the blue continuum emission into a series of knots and clumps, and present evidence that these are most likely due to regions of recent star formation. We investigate several possible triggering mechanisms for the star formation, including direct interactions with the radio source, filaments condensing from the cooling flow, or the result of an interaction with a gas-rich galaxy, which may also have been responsible for fueling the active nucleus. We propose that the properties of the source are plausibly explained in terms of accretion of gas by the cD during an interaction with a gas-rich galaxy, which combined with the fact that this object is located at the center of a dense, high-pressure ICM can account for the high rates of star formation and the strong confinement of the radio source.Comment: Astrophysical Journal, in press, 34 pages, includes 6 PostScript figures. Latex format, uses aaspp4.sty and epsf.sty file

Strategies for Developing Leadership Development Programs to Meet Organizational Goals

Financial business leaders lack strategies to successfully develop leadership development programs to meet organizational goals. Financial business leaders are concerned that all business organizations struggle with leadership development. Grounded in the substitutes for leadership theory, the purpose of this qualitative case study was to explore strategies financial business leaders use to successfully develop leadership development programs to meet organizational goals. The participants comprised three financial executives located in the southeastern United States who are responsible for leadership development. Data were collected using semistructured interviews and a review of organizational electronic information. Three themes emerged: training, resources, and communications. The key recommendation is for executive financial leaders to implement leadership development programs that are tied to organizational goals and values. The implication for positive social change includes leaders being better trained to lead subordinates, which may lead to a more satisfying work environment, lower employee turnover, and the attraction of talented new employees to help produce community viability

Views of healthcare professionals and service users regarding anti, peri and postnatal depression in Oman

IntroductionAnti, peri and postnatal depression is known to affect the relationship between infants and their mothers adversely. Previous studies have identified barriers and facilitators, reported by women and HCPs, related to the identification and management of anti, peri and postnatal depression. However, these studies considered the experiences of women separately from those of the healthcare professionals, even though their experiences of anti, peri and postnatal depression are interconnected. Additionally, there is a lack of research among people living in the Middle East, including Oman, which has one of the highest rates of anti, peri and postnatal depression globally.AimThis study aimed to explore the views and experiences of HCPs and service users relating to anti, peri and postnatal depression from the Middle East perspective.MethodA qualitative descriptive study using semi-structured interviews was conducted. This study took place at the Family Medicine and Community Clinic at University Hospital and three selected primary healthcare centres in Muscat, between May 2020 and February 2021. Purposive sampling was used: 15 HCPs with 2-20 years of clinical experience in anti, peri and postnatal primary care and 13 pregnant patients plus 2 post-birth patients were interviewed. Audio-recordings were transcribed verbatim, and the anonymized transcripts were then entered into the qualitative data management software, NVIVO 12.ResultsA thematic approach was used to analyse the data. Four themes were identified in the data, namely: 1) making sense of anti, peri and postnatal depression; 2) how to deal with anti, peri and postnatal depression; 3) barriers to addressing anti, peri and postnatal depression in primary anti, peri and postnatal care settings; 4) bridging the gap: facilitators in detecting and managing anti, peri and postnatal depression.ConclusionsImproving the identification and management of anti, peri and postnatal depression in primary healthcare systems will require a whole-system approach, with interventions at the patient, practice and comprehensive primary care team levels

Entry, Descent, and Landing with Propulsive Deceleration: Supersonic Retropropulsion Wind Tunnel Testing and Shock Phenomena

The future exploration of the Solar System will require innovations in transportation and the use of entry, descent, and landing (EDL) systems at many planetary landing sites. The cost of space missions has always been prohibitive, and using the natural planetary and planet's moon atmospheres for entry, and descent can reduce the cost, mass, and complexity of these missions. This paper will describe some of the EDL ideas for planetary entry and survey the overall technologies for EDL that may be attractive for future Solar System missions. Future EDL systems may include an inflatable decelerator for the initial atmospheric entry and an additional supersonic retropropulsion (SRP) rocket system for the final soft landing. A three engine retropropulsion configuration with a 2.5 in. diameter sphere-cone aeroshell model was tested in the NASA Glenn Research Center's 1- by 1-ft (11) Supersonic Wind Tunnel (SWT). The testing was conducted to identify potential blockage issues in the tunnel, and visualize the rocket flow and shock interactions during supersonic and hypersonic entry conditions. Earlier experimental testing of a 70deg Viking-like (sphere-cone) aeroshell was conducted as a baseline for testing of a SRP system. This baseline testing defined the flow field around the aeroshell and from this comparative baseline data, retropropulsion options will be assessed. Images and analyses from the SWT testing with 300- and 500-psia rocket engine chamber pressures are presented here. In addition, special topics of electromagnetic interference with retropropulsion induced shock waves and retropropulsion for Earth launched booster recovery are also addressed

Microbes in beach sands : integrating environment, ecology and public health

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Reviews in Environmental Science and Bio/Technology 13 (2014): 329-368, doi:10.1007/s11157-014-9340-8.Beach sand is a habitat that supports many microbes, including viruses, bacteria, fungi and protozoa (micropsammon). The apparently inhospitable conditions of beach sand environments belie the thriving communities found there. Physical factors, such as water availability and protection from insolation; biological factors, such as competition, predation, and biofilm formation; and nutrient availability all contribute to the characteristics of the micropsammon. Sand microbial communities include autochthonous species/phylotypes indigenous to the environment. Allochthonous microbes, including fecal indicator bacteria (FIB) and waterborne pathogens, are deposited via waves, runoff, air, or animals. The fate of these microbes ranges from death, to transient persistence and/or replication, to establishment of thriving populations (naturalization) and integration in the autochthonous community. Transport of the micropsammon within the habitat occurs both horizontally across the beach, and vertically from the sand surface and ground water table, as well as at various scales including interstitial flow within sand pores, sediment transport for particle-associated microbes, and the large-scale processes of wave action and terrestrial runoff. The concept of beach sand as a microbial habitat and reservoir of FIB and pathogens has begun to influence our thinking about human health effects associated with sand exposure and recreational water use. A variety of pathogens have been reported from beach sands, and recent epidemiology studies have found some evidence of health risks associated with sand exposure. Persistent or replicating populations of FIB and enteric pathogens have consequences for watershed/beach management strategies and regulatory standards for safe beaches. This review summarizes our understanding of the community structure, ecology, fate, transport, and public health implications of microbes in beach sand. It concludes with recommendations for future work in this vastly under-studied area.2015-05-0