Recent progress in the development of a solar neutron tracking device (SONTRAC)

We report the results of recent calibration data analysis of a prototype scintillating fiber tracking detector system designed to perform imaging, spectroscopy and particle identification on 20 to 250 MeV neutrons and protons. We present the neutron imaging concept and briefly review the detection principle and the prototype description. The prototype detector system records ionization track data on an event-by-event basis allowing event selection criteria to be used in the off-line analysis. Images of acrylic phantoms from the analysis of recent proton beam calibrations are presented as demonstrations of the particle identification, imaging and energy measurement capabilities. The measured position resolution is \u3c 500 micrometers . The measured energy resolution is 14.2 percent at 35 MeV. The detection techniques employed can be applied to measurements in a variety of disciplines including solar and atmospheric physics, radiation therapy and nuclear materials monitoring. These applications are discussed briefly as are alternative detector configurations and future development plans

Colloids in light fields: particle dynamics in random and periodic energy landscapes

The dynamics of colloidal particles in potential energy landscapes have mainly been investigated theoretically. In contrast, here we discuss the experimental realization of potential energy landscapes with the help of light fields and the observation of the particle dynamics by video microscopy. The experimentally observed dynamics in periodic and random potentials are compared to simulation and theoretical results in terms of, e.g. the mean-squared displacement, the time-dependent diffusion coefficient or the non-Gaussian parameter. The dynamics are initially diffusive followed by intermediate subdiffusive behaviour which again becomes diffusive at long times. How pronounced and extended the different regimes are, depends on the specific conditions, in particular the shape of the potential as well as its roughness or amplitude but also the particle concentration. Here we focus on dilute systems, but the dynamics of interacting systems in external potentials, and thus the interplay between particle-particle and particle-potential interactions, is also mentioned briefly. Furthermore, the observed dynamics of dilute systems resemble the dynamics of concentrated systems close to their glass transition, with which it is compared. The effect of certain potential energy landscapes on the dynamics of individual particles appears similar to the effect of interparticle interactions in the absence of an external potential

Feedback in the Antennae Galaxies (NGC 4038/9): I. High-Resolution Infrared Spectroscopy of Winds from Super Star Clusters

We present high-resolution (R ~ 24,600) near-IR spectroscopy of the youngest super star clusters (SSCs) in the prototypical starburst merger, the Antennae Galaxies. These SSCs are young (3-7 Myr old) and massive (10^5 - 10^7 M_sun for a Kroupa IMF) and their spectra are characterized by broad, extended Br-gamma emission, so we refer to them as emission-line clusters (ELCs) to distinguish them from older SSCs. The Brgamma lines of most ELCs have supersonic widths (60-110 km/s FWHM) and non-Gaussian wings whose velocities exceed the clusters' escape velocities. This high-velocity unbound gas is flowing out in winds that are powered by the clusters' massive O and W-R stars over the course of at least several crossing times. The large sizes of some ELCs relative to those of older SSCs may be due to expansion caused by these outflows; many of the ELCs may not survive as bound stellar systems, but rather dissipate rapidly into the field population. The observed tendency of older ELCs to be more compact than young ones is consistent with the preferential survival of the most concentrated clusters at a given age.Comment: Accepted to Ap

A scintillating plastic fiber tracking detector for neutron and proton imaging and spectroscopy

We report the results of recent calibration data analysis of a prototype scintillating fiber tracking detector system designed to perform imaging, spectroscopy and particle identification on 20 to 250 MeV neutrons and protons. We present the neutron imaging concept and briefly review the detection principle and the prototype description. The prototype detector system records ionization track data on an event-by-event basis allowing event selection criteria to be used in the off-line analysis. Images of acrylic phantoms from the analysis of recent proton beam calibrations (14 to 65 MeV range) are presented as demonstrations of the particle identification, imaging and energy measurement capabilities. The measured position resolution is c 500 pm. The measured energy resolution (AE/E, FWHM) is 14.2% at 35 MeV. An effective technique for track identification and data compression is presented. The detection techniques employed can be applied to measurements in a variety of disciplines including solar and atmospheric physics, radiation therapy and nuclear materials monitoring. These applications are discussed briefly as are alternative detector configurations and future development plans

The Structure and Star-Formation History of NGC 5461

We compute photoionization models for the giant extragalactic H II region NGC 5461, and compare their predictions to several observational constraints. Since we aim at reproducing not only the global properties of the region, but its local structure also, the models are constrained to reproduce the observed density profile, and our analysis takes into consideration the bias introduced by the shapes and sizes of the slits used by different observers. We find that an asymmetric nebula with a gaussian density distribution, powered by a young burst of 3.1 Myr, satisfactorily reproduces most of the constraints, and that the star-formation efficiency inferred from the model agrees with current estimates. Our results strongly depend on the assumed density law, since constant density models overestimate the hardness of the ionizing field, affecting the deduced properties of the central stellar cluster. We illustrate the features of our best model, and discuss the possible sources of errors and uncertainties affecting the outcome of this type of studies.Comment: 33 pages (LaTeX), 3 .eps figures. to be published in ApJ, May 200

Trends in Cause of Death among Puerto Rican and United States Multiple Myeloma Patients

Background/Objective: Multiple myeloma (MM) is an incurable, yet treatable, cancer of plasma cells. Due to recent improvements in treatment, people diagnosed with MM have been living longer, and other co-morbid conditions may be of increasing importance. This study examines temporal trends in specific causes of death among MM patients in Puerto Rico (PR) and United States (US). Methods: We analyzed primary cause of death among all incident MM cancer cases recorded in the Puerto Rico Central Cancer Registry (PRCCR) (n=3,018) and the US Surveillance, Epidemiology, and End Results Program (SEER) (n=67,733) between 1987-2013, overall and by follow-up time, age, and sex. We calculated the cumulative incidence of death due to seven selected causes and analyzed age-adjusted mortality trends by MM and other causes using joinpoint regression. Results: MM accounted for 71.7% and 71.3% of all reported deaths in PR and US, respectively, among people diagnosed with MM. In PR, the proportion of patients that died from MM decreased with increasing follow-up time since diagnosis (72.3% of deaths with ≤2 years vs 65.6% with \u3e5 years of follow-up) and the proportion of patients who died from circulatory (4.6% vs 9.0%) and respiratory system (3.7% vs 5.0%) diseases increased slightly. A similar trend of decreasing MM deaths with follow-up time was observed in the US (73.2% of deaths with ≤2 years vs 66.5% with \u3e5 years of follow-up). Joinpoint regression showed a decreasing trend in MM mortality in the US (APC1987-2007=-2.8%, and APC2007-2013=-18.4%) and a similar, though somewhat weaker, trend in PR (APC1987-2013=-2.73). Conclusion: In both PR and the US, people diagnosed with MM are still more likely to die from MM than from another cause. However, a decrease in MM mortality is evident, particularly in more recent years, but this decrease is lower in Puerto Rico

OSIRIS Software: The Mask Designer Tool

OSIRIS is a Day One instrument that will be available at the 10m GTC telescope which is being built at La Palma observatory in the Canary Islands. This optical instrument is designed to obtain wide-field narrow-band images using tunable filters and to do low-resolution spectroscopy in both long-slit and multislit modes. For the multislit spectroscopy mode, we have developed a software to assist the observers to design focal plane masks. In this paper we describe the characteristics of this Mask Designer tool. We discuss the main design concepts, the functionality and particular features of the software.Comment: 6 figures; accepted for publication in Experimental Astronom