Evolution of the Pairwise Peculiar Velocity Distribution Function in Lagrangian Perturbation Theory

The statistical distribution of the radial pairwise peculiar velocity of galaxies is known to have an exponential form as implied by observations and explicitly shown in N-body simulations. Here we calculate its statistical distribution function using the Zel'dovich approximation assuming that the primordial density fluctuations are Gaussian distributed. We show that the exponential distribution is realized as a transient phenomena on megaparsec scales in the standard cold-dark-matter model.Comment: 19 pages, 8 Postscript figures, AAS LaTe

The Three-point Correlation Function of Galaxies Determined from the 2dF Galaxy Redshift Survey

In a detailed analysis of the three point correlation function (3PCF) for the 2dF Galaxy Redshift Survey we have accurately measured the 3PCF for galaxies of different luminosity. The 3PCF amplitudes [\Qsu or \Qrpu] of the galaxies generally decrease with increasing triangle size and increase with the shape parameter $v$, in qualitative agreement with the predictions for the clustering of dark matter in popular hierarchical CDM models. The 2dFGRS results agree well with the results of Jing & B\"orner for the Las Camapanas Redshift Survey (LCRS), though the measurement accuracy is greatly improved in the present study. The dependence of the 3PCF on luminosity is not significant, but there seems to be a trend for the brightest galaxy sample to have a lower amplitude than the fainter ones. Comparing the measured 3PCF amplitudes [\Qsu or \Qrpu] to the prediction of a WMAP concordance model, we find that the measured values are consistently lower than the predicted ones for dark matter. This is most pronounced for the brightest galaxies, for which about one-half of the predicted $Q$ value provides a good description of \Qrpu for the 2dFGRS data. For a less luminous sample, the $Q$ values are also smaller than in the dark matter model on small scales, but on scales larger than s=8 \mpc and r_p=3.25 \mpc they reach the model values. We discuss implications for current theories of galaxy formation.Comment: 39 pages, 18 figures, ApJ, published version; minor changes to the previous versio

A Galaxy-Weighted Measure of the Relative Peculiar Velocity Dispersion

The relative pair dispersion of galaxies has for the past decade been the standard measure of the thermal energy of fluctuations in the observed galaxy distribution. This statistic is known to be unstable, since it is a pair-weighted measure that is very sensitive to rare, rich clusters of galaxies. As a more stable alternative, we here present a single-particle-weighted statistic $\sigma_1$, which can be considered as an estimate of the one-dimensional rms peculiar velocity dispersion of galaxies relative to their neighbors, and which can be interpreted by means of a filtered version of the Cosmic-Energy equation. We calculate this statistic for the all-sky survey of IRAS galaxies, finding $\sigma_1=95 \pm 16$ km/sec. The UGC catalog yields a higher value, $\sigma_1=130 \pm 15$ km/s. We calibrate our procedure by means of mock catalogs constructed from N-body simulations and find that our method is stable and has modest biases which can easily be corrected. We use the measured values of $\sigma_1$ in a filtered Layzer-Irvine equation to obtain an estimate of $\tilde\Omega \equiv \Omega/b^2$. We find that $\tilde\Omega\approx 0.14 \pm 0.05$ for both the IRAS and UGC catalogs, which is slightly lower than other recent determinations, but is consistent with a trend of an effective $\Omega$ that increases gradually with scale.Comment: 21 pages, plain Tex, including 3 figures. to appear in the Astrophysical Journa

Does the Burglar Also Disturb the Neighbor? Crime Spillovers on Individual Well-Being

Indirect psychological effects induced by crime are likely to contribute significantly to the total costs of crime beyond the financial costs of direct victimization. Using detailed crime statistics for the whole of Germany and linking them to individual-level mental health information from the German Socio-Economic Panel, we analyze whether local crime rates affect the mental health of residents. We estimate that a one standard deviation increase in local violent crime rates significantly decreases individual mental well-being among residents by, on average, one percent. Smaller effects are found for property and total crime rates. Results are insensitive to migration and not isolated to urban areas, but are rather driven by less densely populated regions. In contrast to previous literature on vulnerability to crime, we find that men, more educated and singles react more to variation in violent crime rates in their neighborhoods. One potential explanation could be that those who are more fearful of crime have developed better coping strategies and, hence, react less to changes in crime.Indirekte psychologische Effekte stellen möglicherweise einen erheblichen Teil der durch Kriminalität verursachten Gesamtkosten dar. Um zu analysieren, ob regionale Kriminalitätsraten die mentale Gesundheit beeinflussen, nutzen wir detaillierte Kriminalitätsinformationen für Deutschland und verknüpfen diese mit Informationen zu individueller mentaler Gesundheit aus dem Sozio-ökonomischen Panel. Unsere Schätzergebnisse implizieren, dass der Anstieg um eine Standardabweichung in der Gewaltverbrechensrate das mentale Wohlbefinden der lokalen Bevölkerung signifikant um durchschnittlich ein Prozent reduziert. Für Eigentumsdelikte und die Gesamtkriminalitätsrate beobachten wir geringere Effekte. Die Ergebnisse werden weder durch Wohnortwechsler beeinflusst noch sind sie auf urbane Regionen begrenzt, sondern sind vielmehr durch weniger dicht besiedelte Regionen getrieben. Im Gegensatz zur Literatur zur Angst vor Kriminalität beobachten wir, dass Männer, höher Gebildete und Alleinstehende sensibler auf Veränderungen in der regionalen Gewaltverbrechensrate reagieren. Eine Erklärung hierfür könnte sein, dass diejenigen, die mehr Angst vor Kriminalität haben, entsprechende Coping-Strategien entwickelt haben und daher auch weniger auf Veränderungen in der Kriminalitätsrate reagieren

Coherent methods in the X-ray sciences

X-ray sources are developing rapidly and their coherent output is growing extremely rapidly. The increased coherent flux from modern X-ray sources is being matched with an associated rapid development in experimental methods. This article reviews the literature describing the ideas that utilise the increased brilliance from modern X-ray sources. It explores how ideas in coherent X-ray science are leading to developments in other areas, and vice versa. The article describes measurements of coherence properties and uses this discussion as a base from which to describe partially-coherent diffraction and X-ray phase contrast imaging, with its applications in materials science, engineering and medicine. Coherent diffraction imaging methods are reviewed along with associated experiments in materials science. Proposals for experiments to be performed with the new X-ray free-electron-lasers are briefly discussed. The literature on X-ray photon correlation spectroscopy is described and the features it has in common with other coherent X-ray methods are identified. Many of the ideas used in the coherent X-ray literature have their origins in the optical and electron communities and these connections are explored. A review of the areas in which ideas from coherent X-ray methods are contributing to methods for the neutron, electron and optical communities is presented.Comment: A review articel accepted by Advances in Physics. 158 pages, 29 figures, 3 table

Functional and quality of life outcomes of localised prostate cancer treatments (prostate testing for cancer and treatment [ProtecT] study)

Objective To investigate the functional and quality of life (QoL) outcomes of treatments for localised prostate cancer and inform treatment decision-making. Patients and Methods Men aged 50–69 years diagnosed with localised prostate cancer by prostate-specific antigen testing and biopsies at nine UK centres in the Prostate Testing for Cancer and Treatment (ProtecT) trial were randomised to, or chose one of, three treatments. Of 2565 participants, 1135 men received active monitoring (AM), 750 a radical prostatectomy (RP), 603 external-beam radiotherapy (EBRT) with concurrent androgen-deprivation therapy (ADT) and 77 low-dose-rate brachytherapy (BT, not a randomised treatment). Patient-reported outcome measures (PROMs) completed annually for 6 years were analysed by initial treatment and censored for subsequent treatments. Mixed effects models were adjusted for baseline characteristics using propensity scores. Results Treatment-received analyses revealed different impacts of treatments over 6 years. Men remaining on AM experienced gradual declines in sexual and urinary function with age (e.g., increases in erectile dysfunction from 35% of men at baseline to 53% at 6 years and nocturia similarly from 20% to 38%). Radical treatment impacts were immediate and continued over 6 years. After RP, 95% of men reported erectile dysfunction persisting for 85% at 6 years, and after EBRT this was reported by 69% and 74%, respectively (P < 0.001 compared with AM). After RP, 36% of men reported urinary leakage requiring at least 1 pad/day, persisting for 20% at 6 years, compared with no change in men receiving EBRT or AM (P < 0.001). Worse bowel function and bother (e.g., bloody stools 6% at 6 years and faecal incontinence 10%) was experienced by men after EBRT than after RP or AM (P < 0.001) with lesser effects after BT. No treatment affected mental or physical QoL. Conclusion Treatment decision-making for localised prostate cancer can be informed by these 6-year functional and QoL outcomes