The SBF Survey of Galaxy Distances. I. Sample Selection, Photometric Calibration, and the Hubble Constant

We describe a program of surface brightness fluctuation (SBF) measurements for determining galaxy distances. This paper presents the photometric calibration of our sample and of SBF in general. Basing our zero point on observations of Cepheid variable stars, we find that the absolute SBF magnitude in the Kron-Cousins I band correlates well with the mean (V-I)o color of a galaxy according to M_Ibar = (-1.74 +/- 0.07) + (4.5 +/- 0.25) [ (V-I)o - 1.15 ] for 1.0 < (V-I) < 1.3. This agrees well with theoretical estimates from stellar population models. Comparisons between SBF distances and a variety of other estimators, including Cepheid variable stars, the Planetary Nebula Luminosity Function (PNLF), Tully-Fisher (TF), Dn-sigma, SNII, and SNIa, demonstrate that the calibration of SBF is universally valid and that SBF error estimates are accurate. The zero point given by Cepheids, PNLF, TF (both calibrated using Cepheids), and SNII is in units of Mpc; the zero point given by TF (referenced to a distant frame), Dn-sigma and SNIa is in terms of a Hubble expansion velocity expressed in km/s. Tying together these two zero points yields a Hubble constant of H_0 = 81 +/- 6 km/s/Mpc. As part of this analysis, we present SBF distances to 12 nearby groups of galaxies where Cepheids, SNII, and SNIa have been observed.Comment: 29 pages plus 8 figures; LaTeX (AASTeX) uses aaspp4.sty (included); To appear in The Astrophysical Journal, 1997 February 1 issue; Compressed PostScript available from ftp://mars.tuc.noao.edu/sbf

Autonomic Nervous System and Neurocardiac Physiopathology

The autonomic nervous system regulates multiple physiological functions; how distinct neurons in peripheral autonomic and intrathoracic ganglia communicate remains to be established. Increasing focus is being paid to functionality of the neurocardiac axis and crosstalk between the intrinsic nervous system and diverse organ systems. Current findings indicate that progression of cardiovascular disease comprises peripheral and central aspects of the cardiac nervous system hierarchy. Indeed, autonomic neuronal dysfunction is known to participate in arrhythmogenesis and sudden cardiac death; diverse interventions (pharmacological, non-pharmacological) that affect neuronal remodeling in the heart following injury caused by cardiovascular disease (congestive heart failure, etc.) or acute myocardial infarction are being investigated. Herein we examine recent findings from clinical and animal studies on the role of the intrinsic cardiac nervous system on regulation of myocardial perfusion and the consequences of cardiac injury. We also discuss different interventions that target the autonomic nervous system, stimulate neuronal remodeling and adaptation, and thereby optimize patient outcomes

The Galaxy Populations of X-Ray Detected, Poor Groups

(Abridged) We determine the quantitative morphology and star formation properties of galaxies in six nearby X-ray detected, poor groups using multi-object spectroscopy and wide-field R imaging. We measure structural parameters for each galaxy by fitting a PSF-convolved, two component model to their surface brightness profiles. To compare directly the samples, we fade, smooth, and rebin each galaxy image so that we effectively observe each galaxy at the same redshift (9000 km/s) and physical resolution (0.87h^(-1) kpc). We compare results for the groups to a sample of field galaxies. We find that: 1) Galaxies spanning a wide range in morphological type and luminosity are well-fit by a de Vaucouleurs bulge with exponential disk profile. 2) Morphologically classifying these nearby group galaxies by their bulge fraction (B/T) is fairly robust on average, even when their redshift has increased by up to a factor of four and the effective resolution of the images is degraded by up to a factor of five. 3) The fraction of bulge-dominated systems in these groups is higher than in the field (~50% vs. ~20%). 4) The fraction of bulge-dominated systems in groups decreases with increasing radius, similar to the morphology-radius (~density) relation observed in galaxy clusters. 5) Current star formation in group galaxies is correlated with significant morphological asymmetry for disk-dominated systems (B/T<0.4). 6) The group galaxies that are most disk-dominated (B/T<0.2) are less star forming and asymmetric on average than their counterparts in the field.Comment: Accepted for publication in the Astrophysical Journal (26 pages + 12 figures); Figs 1 & 2 also available at http://www.ucolick.org/~vy/astronomy/groups_figs.tar.g

Below-ground biotic interactions moderated the postglacial range dynamics of trees

Tree range shifts during geohistorical global change events provide a useful real-world model for how future changes in forest biomes may proceed. In North America, during the last deglaciation, the distributions of tree taxa varied significantly in the rate and direction of their responses for reasons that remain unclear. Local-scale processes such as establishment, growth, and resilience to environmental stress ultimately influence range dynamics. Despite the fact that interactions between trees and soil biota are known to influence local-scale processes profoundly, evidence linking belowground interactions to distribution dynamics remains scarce. • We evaluated climate velocity and plant traits related to dispersal, environmental tolerance, and belowground symbioses, as potential predictors of the geohistorical rates of expansion and contraction of the core distributions of tree genera between 16-7kaBP. • The receptivity of host genera towards ectomycorrhizal fungi was strongly supported as a positive predictor of poleward rates of distribution expansion, and seed mass was supported as a negative predictor. Climate velocity gained support as a positive predictor of rates of distribution contraction, but not expansion. • Our findings indicate that understanding how tree distributions, and thus forest ecosystems, respond to climate change requires the simultaneous consideration of traits, biotic interactions, and abiotic forcing

Job Satisfaction and Psychological Distress among Help-Seeking Men: Does Meaning in Life Play a Role?

Men’s low job satisfaction has been shown to be associated with greater symptoms of psychological distress. Meaning in life may be an important factor in this relationship, but its role as a mediator has not been reported. The present study investigated meaning in life as a mediator in the relationship between job satisfaction and psychological distress among men. A total of 229 employed Canadian men participated in a cross-sectional survey, completing measures of depression and anxiety symptoms, anger severity, job satisfaction, and the presence of meaning in life. Zero-order correlations were calculated, and regression with mediation analyses were conducted; two models were tested: one for anxiety/depression symptoms and one for anger, as the dependent variables. Both mediation models emerged as significant, revealing a significant mediating effect for job satisfaction on the symptoms of psychological distress (anxiety/depression symptoms, anger) through meaning in life, even while controlling for salient confounding variables including COVID-related impacts. Lower job satisfaction was associated with less meaning in life, which in turn was associated with more symptoms of depression, anxiety, and anger. The findings highlight the importance of job satisfaction in the promotion of a sense of meaning in life among men, leading to improved psychological well-being both inside and outside of the workplace

Green engagement: An investigation into the relationship of Millennial engagement and an organization’s sustainable performance score

Since the start of the 21st century, the issue of sustainability in business and Human Resource practices has been a central topic of interest. More recently, human resources has come under considerable pressure to prove its worth, primarily by producing a more productive and engaged workforce. Sustainability has, thus, become an extremely interesting avenue of study for HR professionals as, at its core, sustainable practices aim to better all parts of an organization from the social, to the environmental, to the financial (the three components of the triple bottom line). This study will investigate the relationship between the extent to which Millennials are engaged in an organization and that organization’s score on sustainable performance measures

Transfer of 13C between paired Douglas-fir seedlings reveals plant kinship effects and uptake of exudates by ectomycorrhizas

• Processes governing the fixation, partitioning, and mineralization of carbon in soils are under increasing scrutiny as we develop a more comprehensive understanding of global carbon cycling. Here we examined fixation by Douglas-fir seedlings and transfer to associated ectomycorrhizal fungi, soil microbes, and full-sibling or non-sibling neighbouring seedlings. • Stable isotope probing with 99% 13C-CO2 was applied to trace 13C-labelled photosynthate throughout plants, fungi, and soil microbes in an experiment designed to assess the effect of relatedness on 13C-transfer between plant pairs. The fixation and transfer of 13C-label to plant, fungal, and soil microbial tissue was examined in biomass and PLFAs. • After a 6-day chase period, approximately 26.8% of the 13C remaining in the system was translocated belowground. Enrichment was proportionally greatest in ectomycorrhizal biomass. The presence of mesh barriers (0.5 or 35 µm) between seedlings did not restrict 13C-transfer. • Fungi were the primary recipients of 13C-labelled photosynthate throughout the system, representing 60–70% of total 13C-enriched phospholipids. Full-sibling pairs exhibited significantly greater 13C-transfer to recipient roots in two of four Douglas-fir families, representing 3- and 4-fold increases (+ approx. 4 µg excess 13C) compared to non-sibling pairs. The existence of a root/mycorrhizal exudation – hyphal uptake pathway was supported

Association Mapping of Insecticide Resistance in Wild Anopheles gambiae Populations: Major Variants Identified in a Low-Linkage Disequilbrium Genome

Background: Association studies are a promising way to uncover the genetic basis of complex traits in wild populations. Data on population stratification, linkage disequilibrium and distribution of variant effect-sizes for different trait-types are required to predict study success but are lacking for most taxa. We quantified and investigated the impacts of these key variables in a large-scale association study of a strongly selected trait of medical importance: pyrethroid resistance in the African malaria vector Anopheles gambiae. Methodology/Principal Findings: We genotyped <1500 resistance-phenotyped wild mosquitoes from Ghana and Cameroon using a 1536-SNP array enriched for candidate insecticide resistance gene SNPs. Three factors greatly impacted study power. (1) Population stratification, which was attributable to co-occurrence of molecular forms (M and S), and cryptic within-form stratification necessitating both a partitioned analysis and genomic control. (2) All SNPs of substantial effect (odds ratio, OR.2) were rare (minor allele frequency, MAF,0.05). (3) Linkage disequilibrium (LD) was very low throughout most of the genome. Nevertheless, locally high LD, consistent with a recent selective sweep, and uniformly high ORs in each subsample facilitated significant direct and indirect detection of the known insecticide target site mutation kdr L1014F (OR<6; P,1026), but with resistance level modified by local haplotypic background. Conclusion: Primarily as a result of very low LD in wild A. Gambiae, LD-based association mapping is challenging, but is feasible at least for major effect variants, especially where LD is enhanced by selective sweeps. Such variants will be of greatest importance for predictive diagnostic screening

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N_2)SiMe_3](PEt_3)_3

Reaction of RhCl(PR_3)_n (R = Me (n = 4), Et (n = 3)) and RhCl(CO)(PEt_3)_2 with (trimethylsilyl)diazomethyl lithium at −78 °C in ether yields the three complexes Rh[C(N_2)SiMe_3](PEt_3)_3 (1), Rh[C(N_2)SiMe_3](PMe_3)_4 (2), and Rh[C(N_2)SiMe_3](CO)(PEt_3)_2 (3). 2 could not be isolated as a solid at room temperature but 1 was precipitated as red crystals that were stable enough to be handled under argon. X-ray work on 1 reveals a tetrahedrally distorted square-planar geometry with the planar (trimethylsilyl)diazomethyl ligand roughly perpendicular to the P3RhC coordination plane. This distortion makes the PEt3 ligands nonequivalent in the crystal and produces an ABB‘X pattern in the solid-state ^(31)P NMR spectrum. Photolysis of Rh[C(N_2)SiMe_3](PEt_3)_3 leads quantitatively to the dimer [Rh{C(SiMe_3)(PEt_3)}(PEt_3)_2]_2 (4). The presence of the two ylide bridges and terminal phosphines is deduced from the COSY ^(31)P−^(31)P NMR spectrum. This photochemical reactivity suggests that the transient carbene (PEt_3)_3RhC̈(SiMe_3) is electrophilic, which is typical of a singlet carbene. We believe the singlet state is stabilized by the presence of the electron-rich low-spin Rh(PEt3)3 fragment. Reaction with ^nBuNC and ^tBuNC leads to stereo- and regioselective formation of a triazole that is σ bonded to the rhodium center. The X-ray structure of the ^tBuNC derivative Rh[CC(SiMe_3)N_2N^tBu](^tBuNC)_2(PEt_3) (5) shows a distorted square-planar geometry around Rh with the planar triazolato ligand roughly orthogonal to this plane. The probable reaction mechanism involves addition and substitution reactions of isocyanides at Rh followed by insertion into the Rh−C bond

A search for the first massive galaxy clusters

We have obtained deep, multi-band imaging observations around three of the most distant known quasars at redshifts z>6. Standard accretion theory predicts that the supermassive black holes present in these quasars were formed at a very early epoch. If a correlation between black hole mass and dark matter halo mass is present at these early times, then these rare supermassive black holes will be located inside the most massive dark matter halos. These are therefore ideal locations to search for the first clusters of galaxies. We use the Lyman-break technique to identify star-forming galaxies at high redshifts. Our observations show no overdensity of star-forming galaxies in the fields of these quasars. The lack of (dust-free) luminous starburst companions indicates that the quasars may be the only massive galaxies in their vicinity undergoing a period of intense activity.Comment: 6 pages, 2 figures, contributed paper to Proceedings of the Conference "Growing Black Holes" held in Garching, Germany, June 21-25, 2004, edited by A. Merloni, S. Nayakshin and R. Sunyaev, Springer-Verlag series of "ESO Astrophysics Symposia