Comparison of Material Properties and Microstructure of Specimens Built Using the 3D Systems Vanguard HS and Vanguard HiQ+HSSLS Systems

The HiQ upgrade to the 3D Systems Vanguard selective laser sintering (SLS) machine incorporates a revised thermal calibration system and new control software. The paper compares the tensile modulus, tensile strength, elongation at break, flexural modulus, Izod impact resistance and microstructure of two batteries of standard specimens built from recycled Duraform PA (Nylon 12). The first set is built on a Vanguard HS system and the second on the same system with the HiQ upgrade installed. The upgrade reduces user intervention, decreases total build time and improves surface finish. However, using the default processing parameters, tensile, flexure and impact properties are all found to decline after the upgrade is installed.Mechanical Engineerin

Ionization Mechanisms in Jet-Dominated Seyferts: A Detailed Case Study

For the past 10 years there has been an active debate over whether fast shocks play an important role in ionizing emission line regions in Seyfert galaxies. To investigate this claim, we have studied the Seyfert 2 galaxy Mkn 78, using HST UV/optical images and spectroscopy. Since Mkn 78 provides the archetypal jet-driven bipolar velocity field, if shocks are important anywhere they should be important in this object. Having mapped the emission line fluxes and velocity field, we first compare the ionization conditions to standard photoionization and shock models. We find coherent variations of ionization consistent with photoionization model sequences which combine optically thick and thin gas, but are inconsistent with either autoionizing shock models or photoionization models of just optically thick gas. Furthermore, we find absolutely no link between the ionization of the gas and its kinematic state, while we do find a simple decline of ionization degree with radius. We feel this object provides the strongest case to date against the importance of shock related ionization in Seyferts.Comment: 4 pages, 1 figure, to appear in the proceedings of IAU Symposium 222 "The Interplay among Black Holes, Stars and ISM in Galactic Nuclei", T. Storchi Bergmann, L.C. Ho & H.R. Schmitt, ed

Chiral molecules split light: Reflection and refraction in a chiral liquid

A light beam changes direction as it enters a liquid at an angle from another medium, such as air. Should the liquid contain molecules that lack mirror symmetry, then it has been predicted by Fresnel that the light beam will not only change direction, but will actually split into two separate beams with a small difference in the respective angles of refraction. Here we report the observation of this phenomenon. We also demonstrate that the angle of reflection does not equal the angle of incidence in a chiral medium. Unlike conventional optical rotation, which depends on the path-length through the sample, the reported reflection and refraction phenomena arise within a few wavelengths at the interface and thereby suggest a new approach to polarimetry that can be used in microfluidic volumes

An open systems approach to calculating time dependent spectra

A new method to calculate the spectrum using cascaded open systems and master equations is presented. The method uses two state analyzer atoms which are coupled to the system of interest, whose spectrum of radiation is read from the excitation of these analyzer atoms. The ordinary definitions of a spectrum uses two-time averages and Fourier-transforms. The present method uses only one-time averages. The method can be used to calculate time dependent as well as stationary spectra.Comment: 8 pages, revtex, 18 figures, to be published in J.Mod.Op

The Effects of Negative Legacies on the Adjustment of Parentally Bereaved Children and Adolescents

This is a report of a qualitative analysis of a sample of bereaved families in which one parent died and in which children scored in the clinical range on the Child Behavior Check List. The purpose of this analysis was to learn more about the lives of these children. They were considered to be at risk of developing emotional and behavioral problems associated with the death. We discovered that many of these “high risk” children had a continuing bond with the deceased that was primarily negative and troubling for them in contrast to a comparison group of children not at risk from the same study. Five types of legacies, not mutually exclusive, were identified: health related, role related, personal qualities, legacy of blame, and an emotional legacy. Coping behavior on the part of the surviving parent seemed to make a difference in whether or not a legacy was experienced as negative

Programmable telemetry system Patent

Time division multiplexed telemetry transmitting system controlled by programmed memor

X-ray Emission from the Radio Jet in 3C 120

We report the discovery of X-ray emission from a radio knot at a projected distance of 25" from the nucleus of the Seyfert galaxy, 3C 120. The data were obtained with the ROSAT High Resolution Imager (HRI). Optical upper limits for the knot preclude a simple power law extension of the radio spectrum and we calculate some of the physical parameters for thermal bremsstrahlung and synchrotron self-Compton models. We conclude that no simple model is consistent with the data but if the knot contains small regions with flat spectra, these could produce the observed X-rays (via synchrotron emission) without being detected at other wavebands.Comment: 6 pages latex plus 3 ps/eps figures. Uses 10pt.sty and emulateapj.sty. Accepted for publication in the ApJ (6 Jan 99

The X-Ray Zurich Environmental Study (X-ZENS). I. Chandra and XMM-Newton observations of active galactic nuclei in galaxies in nearby groups

We describe X-ray observations with Chandra and XMM-Newton of 18 galaxy groups (M_group ~ 1-6x10^13 Msolar, z~0.05) from the Zurich Environmental Study (ZENS). We aim to establish the frequency and properties, unaffected by host galaxy dilution and obscuration, of AGNs in central and satellite galaxy members, also as a function of halo-centric distance. X-ray point-source detections are reported for 22 of 177 observed galaxies, down to a limit of f_(0.5-8 keV) ~ 5x10^-15 erg cm^-2 s^-1, corresponding to a limiting luminosity of L_(0.5-8 keV)~3x10^40 erg s^-1. With the majority of the X-ray sources attributed to AGNs of low-to-moderate levels (L/L_Edd>~10^-4), we discuss the detection rate in the context of the occupation of AGNs to halos of this mass scale and redshift, and compare the structural/morphological properties between AGN-active and non-active galaxies of different rank and location within the group halos. We see a slight tendency for AGN hosts to have either relatively brighter/denser disks (or relatively fainter/diffuse bulges) than non-active galaxies of similar mass. At galaxy mass scales <10^11 Msolar, central galaxies appear to be a factor ~4 more likely to host AGNs than satellite galaxies of similar mass. This effect, coupled with the tendency for AGNs to reside in massive galaxies, explains the (weak) trend for AGNs to be preferentially found in the inner regions of groups, with no detectable trend with halo-centric distance in the frequency of AGNs within the satellite population. Finally, our data support other analyses in finding that the rate of decline with redshift of AGN activity in groups matches that of the global AGN population, indicating that either AGNs occur preferentially in groups, or that the evolution rate is independent of halo mass. These trends are of potential importance, and require X-ray coverage of a larger sample to be solidly confirmed.Comment: 18 pages, 13 figures, submitted to The Astrophysical Journal, this is a revised version that addresses the referee's comment

Reproductive Coercion and Relationship Abuse Among Adolescents and Young Women Seeking Care at School Health Centers.

ObjectiveTo investigate demographic differences and evaluate how reproductive coercion and relationship abuse influences young females' care-seeking and sexual health behaviors.MethodsWe conducted a secondary analysis of cross-sectional baseline survey data from sexually active female students (aged 14-19 years) who sought care from school health centers. Outcomes included recent (previous 3 months) reproductive coercion, physical or sexual adolescent relationship abuse, and nonpartner sexual violence victimization. Cluster-adjusted χ tests compared demographics and generalized linear mixed models estimated associations among reproductive coercion, adolescent relationship abuse (physical and sexual abuse in romantic relationships), and care-seeking and sexual health behaviors.ResultsOf 550 sexually active high school females, 12% reported recent reproductive coercion and 17% reported physical or sexual adolescent relationship abuse, with no significant demographic differences. Prevalence of recent nonpartner sexual violence was 17%. There were no observed significant differences in care-seeking behaviors among those with recent reproductive coercion compared with those without. Physical or sexual adolescent relationship abuse was associated with increased odds of seeking testing or treatment for sexually transmitted infections (adjusted odds ratio [aOR] 2.08, 95% CI 1.05-4.13). Females exposed to both adolescent relationship abuse and reproductive coercion had higher odds of having a partner who was 5 or more years older (aOR 4.66, 95% CI 1.51-14.4), having two or more recent sexual partners (aOR 3.86, 95% CI 1.57-9.48), and using hormonal contraception only (aOR 3.77, 95% CI 1.09-13.1 vs hormonal methods with condoms).ConclusionAlmost one in eight females experienced recent reproductive coercion. We did not observe significant demographic differences in reproductive coercion. Partner age and number of sexual partners may elevate risk for abusive relationships. Relationship abuse is prevalent among high school students seeking care, with no clear pattern for case identification. By failing to identify factors associated with harmful partner behaviors, our results support universal assessment for reproductive coercion and relationship abuse among high school-aged adolescents, involving education, resources, and harm-reduction counseling to all patients.Clinical trial registrationClinicalTrials.gov, NCT01678378