Confusion of Diffuse Objects in the X-ray Sky

Most of the baryons in the present-day universe are thought to reside in intergalactic space at temperatures of 10^5-10^7 K. X-ray emission from these baryons contributes a modest (~10%) fraction of the ~ 1 keV background whose prominence within the large-scale cosmic web depends on the amount of non-gravitational energy injected into intergalactic space by supernovae and AGNs. Here we show that the virialized regions of groups and clusters cover over a third of the sky, creating a source-confusion problem that may hinder X-ray searches for individual intercluster filaments and contaminate observations of distant groups.Comment: accepted to ApJ Letters, 7 pages, 3 figure

Vibration in Planetary Gear Systems with Unequal Planet Stiffnesses

An algorithm suitable for a minicomputer was developed for finding the natural frequencies and mode shapes of a planetary gear system which has unequal stiffnesses between the Sun/planet and planet/ring gear meshes. Mode shapes are represented in the form of graphical computer output that illustrates the lateral and rotational motion of the three coaxial gears and the planet gears. This procedure permits the analysis of gear trains utilizing nonuniform mesh conditions and user specified masses, stiffnesses, and boundary conditions. Numerical integration of the equations of motion for planetary gear systems indicates that this algorithm offers an efficient means of predicting operating speeds which may result in high dynamic tooth loads

The Effect of Prenatal Valproate Exposure in Serotonin Transporter Knockout Rats On Anxiety and Cognition: A Gene*Environment Interaction Model of Autism Spectrum Disorder

Autism Spectrum Disorder is a complex neurodevelopmental disorder which is often associated with increased anxiety and deficits in cognitive ability. The present research investigated a potential gene*environment interaction between two factors previously implicated in ASD in a rat model; prenatal exposure to valproate (VPA) and genetic reduction of the serotonin transporter (SERT). Wildtype and heterozygous SERT knockout rats prenatally exposed to VPA or saline on gestational day12.5 (G12.5) were assessed on measures of anxiety: elevated plus-maze and novelty suppressed-feeding and cognitive ability: prepulse inhibition and latent inhibition. A significant main effect was found for VPA exposure in all paradigms, showing increased anxiety-typical behaviour and abnormal cognitive ability. However, no significant effect of genotype or interaction was observed. Results from the present study do not confirm gene*environment interaction between prenatal VPA and heterozygous SERT knockout but this may be due to several factors that are discussed within the thesis. In any case, this study represents a starting point for further studies investigating other combinations of genetic and environmental factors as models of ASD pathogenesis

Vulgar and Ascetic Christians: the Myth of a Higher Spirituality The rhetoric of monastic profession as a second baptism

It is the object of this paper to examine the roots of the rhetoric which developed almost as early as monasticism itself of monastic profession as a “second baptism.” The reader will see how Neo-Platonic thought contributed to the reinforcement of this rhetoric, and how it has been expressed down the ages in both the West and East. Further, this paper examines the challenges this rhetoric received at the hands of the Sixteenth Century Reformers. Finally, it suggests a way to move toward a deeper investigation of the ongoing challenges within the Roman Catholic Church to advance and reinforce a full appreciation of the “universal call to holiness” as taught by the Second Vatican Council and the interrelation of the order of the baptized and the monastic orders. This will lend a proper appreciation for the way the universal call is embodied in the individual lives of Christians

Dynamics of early planetary gear trains

A method to analyze the static and dynamic loads in a planetary gear train was developed. A variable-variable mesh stiffness (VVMS) model was used to simulate the external and internal spur gear mesh behavior, and an equivalent conventional gear train concept was adapted for the dynamic studies. The analysis can be applied either involute or noninvolute spur gearing. By utilizing the equivalent gear train concept, the developed method may be extended for use for all types of epicyclic gearing. The method is incorporated into a computer program so that the static and dynamic behavior of individual components can be examined. Items considered in the analysis are: (1) static and dynamic load sharing among the planets; (2) floating or fixed Sun gear; (3) actual tooth geometry, including errors and modifications; (4) positioning errors of the planet gears; (5) torque variations due to noninvolute gear action. A mathematical model comprised of power source, load, and planetary transmission is used to determine the instantaneous loads to which the components are subjected. It considers fluctuating output torque, elastic behavior in the system, and loss of contact between gear teeth. The dynamic model has nine degrees of freedom resulting in a set of simultaneous second order differential equations with time varying coefficients, which are solved numerically. The computer program was used to determine the effect of manufacturing errors, damping and component stiffness, and transmitted load on dynamic behavior. It is indicated that this methodology offers the designer/analyst a comprehensive tool with which planetary drives may be quickly and effectively evaluated

A Thorium Metal-Organic Framework with Outstanding Thermal and Chemical Stability.

A new thorium metal-organic framework (MOF), Th(OBA)2 , where OBA is 4,4'-oxybis(benzoic) acid, has been synthesized hydrothermally in the presence of a range of nitrogen-donor coordination modulators. This Th-MOF, described herein as GWMOF-13, has been characterized by single-crystal and powder X-ray diffraction, as well as through a range of techniques including gas sorption, thermogravimetric analysis (TGA), solid-state UV/Vis and luminescence spectroscopy. Single-crystal X-ray diffraction analysis of GWMOF-13 reveals an interesting, high symmetry (cubic Ia 3 ‾ d) structure, which yields a novel srs-a topology. Most notably, TGA analysis of GWMOF-13 reveals framework stability to 525 °C, matching the thermal stability benchmarks of the UiO-66 series MOFs and zeolitic imidazolate frameworks (ZIFs), and setting a new standard for thermal stability in f-block based MOFs

A multi-purpose method for analysis of spur gear tooth loading

A large digitized approach was developed for the static and dynamic load analysis of spur gearing. An iterative procedure was used to calculate directly the "variable-variable" gear mesh stiffness as a function of transmitted load, gear tooth profile errors, gear tooth deflections and gear hub torsional deformation, and position of contacting profile points. The developed approach can be used to analyze the loads, Hertz stresses, and PV for the normal and high contrast ratio gearing, presently the modeling is limited to the condition that for a given gear all teeth have identical spacing and profiles (with or without surface imperfections). Certain types of simulated sinusoidal profile errors and pitting can cause interruptions of the gear mesh stiffness function and, thus, increase the dynamic loads in spur gearing. In addition, a finite element stress and mesh subprogram was developed for future introduction into the main program for calculating the gear tooth bending stresses under dynamic loads