The local space density of dwarf galaxies

We estimate the luminosity function of field galaxies over a range of ten magnitudes (-22 < M_{B_J} < -12 for H_0 = 100 km/s/Mpc) by counting the number of faint APM galaxies around Stromlo-APM redshift survey galaxies at known distance. The faint end of the luminosity function rises steeply at M_{B_J} \approx -15, implying that the space density of dwarf galaxies is at least two times larger than predicted by a Schechter function with flat faint-end slope. Such a high abundance of dwarf galaxies at low redshift can help explain the observed number counts and redshift distributions of faint galaxies without invoking exotic models for galaxy evolution.Comment: 20 pages, 5 included postscript figures, uses AAS LaTex macros. Accepted for publication in the Astrophysical Journal. Two figures and associated discussion added; results and conclusions unchange

Manipulating forest structure and ground flora composition for the restoration of oak woodlands and the reconstruction of oak savannas in Central Missouri

Managers across the central US are interested in restoring once abundant ecosystems such as savannas and woodlands. These restorations are inundated with challenges like creating the appropriate native plant structure and composition. This project will evaluate methods to 1) reintroduce woody structure to a restored prairie to create a savanna, and 2) establish native woodland ground flora in a recently thinned mature oak stand for woodland restoration. Savannas require frequent fire for maintenance; as such, newly planted trees in a prairie will require protection from frequent fire. For our first project objective, we planted 900 oak (Quercus) seedlings of five species grown by two nursery production methods [containerized root production method (RPM) or bare-root] and used weed barriers and a mechanical fuel removal treatment to protect them. Species and stock type selection were the most important treatments in establishing oak trees in a restored prairie, while the mechanical fuel removal and weed barrier treatments had little effect. Returning a degraded oak forest to a woodland community may require active seeding of woodland ground flora and seedbed manipulation due to a depauperate seed bank and low potential for desired species to colonize the site. For our second project objective, establishing ground flora in structurally restored woodlands, we seeded a diverse mix of native herbaceous species that have various light tolerances on plots of varying overstory tree density where the litter was either raked or not. Reduced basal area, seeding of native ground flora, and time since treatment were significant for increasing abundance, diversity, and the quality of the plant community, while raking had little effect.Includes bibliographical references

Tramp Novae Between Galaxies in the Fornax Cluster: Tracers of Intracluster Light

We report the results of a survey for novae in and between the galaxies of the Fornax cluster. Our survey provides strong evidence that intracluster novae exist and that they provide a useful, independent measure of the intracluster light in Fornax. We discovered six strong nova candidates in six distinct epochs spanning eleven years from 1993 to 2004. The data were taken with the 4m and the 1.5m telescopes at CTIO. The spatial distribution of the nova candidates is consistent with $\sim$16-41% of the total light in the cluster being in the intracluster light, based on the ratio of the number of novae we discovered in intracluster space over the total number of novae discovered plus a simple completeness correction factor. This estimate is consistent with independent measures of intracluster light in Fornax and Virgo using intracluster planetary nebulae. The accuracy of the intracluster light measurement improves with each survey epoch as more novae are discovered.Comment: 30 pages, 10 figures, accepted for publication in the Astrophysical Journal (Sep 9, 2004). Version 2: Added references. Full resolution versions of figures 1-7 and 10 can be found at http://astrowww.phys.uvic.ca/~neill/fnx

Large-scale structure and matter in the universe

This paper summarizes the physical mechanisms that encode the type and quantity of cosmological matter in the properties of large-scale structure, and reviews the application of such tests to current datasets. The key lengths of the horizon size at matter-radiation equality and at last scattering determine the total matter density and its ratio to the relativistic density; acoustic oscillations can diagnose whether the matter is collisionless, and small-scale structure or its absence can limit the mass of any dark-matter relic particle. The most stringent constraints come from combining data on present-day galaxy clustering with data on CMB anisotropies. Such an analysis breaks the degeneracies inherent in either dataset alone, and proves that the universe is very close to flat. The matter content is accurately consistent with pure Cold Dark Matter, with about 25% of the critical density, and fluctuations that are scalar-only, adiabatic and scale-invariant. It is demonstrated that these conclusions cannot be evaded by adjusting either the equation of state of the vacuum, or the total relativistic density.Comment: 17 Pages. Review paper from the January 2003 Royal Society Discussion Meeting, "The search for dark matter and dark energy in the universe

Weak Gravitational Lensing by a Sample of X-ray Luminous Clusters of Galaxies -- III. Serendipitous Weak Lensing Detections of Dark and Luminous Mass Concentrations

In the course of a weak gravitational lensing survey of 39 clusters of galaxies,covering a total sky area of ~1 square degree, we have serendipitously discovered mass concentrations in the fields of A1705 and A1722 which are most probably not associated with the main cluster target. By combining weak lensing information with two-color galaxy photometry in fields centered on our sample clusters, we identify a new cluster candidate at z~0.5 in the field of A1705. This cluster candidate also displays strong lensing in the form of a giant luminous arc. The new mass concentration in the field of A1722 also seems to be associated with an optically luminous cluster of galaxies at z~0.5, but in this case there is some evidence for additional structures along the line of sight that may contribute to the lensing signal. A third cluster, A959, has a dark sub-clump which shows interesting morphological evidence in the mass map for being associated with the main cluster. This is the first case where there is any significant evidence for a physical association between a dark sub-clump (discovered from weak lensing) and a normal cluster. Analysis of archival X-ray data shows that the three new mass concentrations are not firmly detected in X-rays and that they are X-ray underluminous.Comment: 14 pages, 10 figures, version accepted by ApJ. See http://www.nordita.dk/~dahle/paper3.ps.gz for a version with high-resolution figures and Fig.5 in colo

Bayesian estimation of in-game home team win probability for National Basketball Association games

Maddox, et al. (2022) establish a new win probability estimation for college basketball and compared the results with previous methods of Stern (1994), Desphande and Jensen (2016) and Benz (2019). This paper proposes modifications to the approach of Maddox, et al. (2022) for the NBA game and investigates the performance of the model. Enhancements to the model are developed, and the resulting adjusted model is compared with existing methods and to the ESPN counterpart. To illustrate utility, all methods are applied to the November 23, 2019 game between the Chicago Bulls and Charlotte Hornets.Comment: 15 pages, 7 figures, 5 tables. arXiv admin note: text overlap with arXiv:2204.1177

Switching warfarin to direct oral anticoagulants in atrial fibrillation: Insights from the NCDR PINNACLE registry

BACKGROUND: Previous studies examining the use of direct oral anticoagulants (DOACs) in atrial fibrillation (AF) have largely focused on patients newly initiating therapy. Little is known about the prevalence/patterns of switching to DOACs among AF patients initially treated with warfarin. HYPOTHESIS: To examine patterns of anticoagulation among patients chronically managed with warfarin upon the availability of DOACs and identify patient/practice-level factors associated with switching from chronic warfarin therapy to a DOAC. METHODS: Prospective cohort study of AF patients in the NCDR PINNACLE registry prescribed warfarin between May 1, 2008 and May 1, 2015. Patients were followed at least 1 year (median length of follow-up 375 days, IQR 154-375) through May 1, 2016 and stratified as follows: continued warfarin, switched to DOAC, or discontinued anticoagulation. To identify significant predictors of switching, a three-level multivariable hierarchical regression was developed. RESULTS: Among 383 008 AF patients initially prescribed warfarin, 16.3% (n = 62 620) switched to DOACs, 68.8% (n = 263 609) continued warfarin, and 14.8% (n = 56 779) discontinued anticoagulation. Among those switched, 37.6% received dabigatran, 37.0% rivaroxaban, 24.4% apixaban, and 1.0% edoxaban. Switched patients were more likely to be younger, women, white, and have private insurance (all P \u3c .001). Switching was less likely with increased stroke risk (OR, 0.92; 95%CI, 0.91-0.93 per 1-point increase CHA CONCLUSIONS: Among AF patients treated with warfarin between October 1, 2010 and May 1, 2016, one in six were switched to DOACs, with differences across sociodemographic/clinical characteristics and substantial practice-level variation. In the context of current guidelines which favor DOACs over warfarin, these findings help benchmark performance and identify areas of improvement

Introduction

Introduction to issu

Power Spectrum of Velocity Fluctuations in the Universe

We investigate the power spectrum of velocity fluctuations in the universe, $V^2(k)$, starting from four different measures of velocity: (1) the power spectrum of velocity fluctuations from peculiar velocities of galaxies; (2) the rms peculiar velocity of galaxy clusters; (3) the power spectrum of velocity fluctuations from the power spectrum of density fluctuations in the galaxy distribution; (4) and the bulk velocity from peculiar velocities of galaxies. We show that measures (1) and (2) are not consistent with each other and either the power spectrum from peculiar velocities of galaxies is overestimated or the rms cluster peculiar velocity is underestimated. The amplitude of velocity fluctuations derived from the galaxy distribution (measure 3) depends on the parameter $\beta$. We estimate the parameter $\beta$ on the basis of measures (2) and (4). The power spectrum of velocity fluctuations from the galaxy distribution in the Stromlo-APM redshift survey is consistent with the observed rms cluster velocity and with the observed large-scale bulk flow when the parameter $\beta$ is in the range 0.4-0.5. In this case the value of the function $V(k)$ at wavelength $\lambda=120h^{-1}$Mpc is $\sim 350$ km s$^{-1}$ and the rms amplitude of the bulk flow at the radius $r=60h^{-1}$ Mpc is $\sim 340$ km s$^{-1}$. The velocity dispersion of galaxy systems originates mostly from the large-scale velocity fluctuations with wavelengths $\lambda >100h^{-1}$ Mpc.Comment: Astrophysical Journal, Vol. 493, in press: 23 pages, uses AAS Latex, and 14 separate postscript figure