Studies on the Reduction of Radon Plate-Out

The decay of common radioactive gases, such as radon, produces stable isotopes by a sequence of daughter particles with varied half-lives. These daughter particles are a significant source of gamma, neutron, and alpha particle backgrounds that can mimic desired signals in dark matter and neutrinoless double beta decay experiments. In the LUMINA Laboratory at Southern Methodist University (SMU), studies of radon plate-out onto copper samples are conducted using one of XIA's first five UltraLo 1800 alpha counters. We present results from investigations into various mitigation approaches. A custom-built copper holder (in either plastic or metal) has been designed and produced to maximize the copper's exposure to 220Rn. The 220Rn source is a collection of camping lantern mantles. We present the current status of control and experimental methods for addressing radon exposure levels.Comment: 4 pages, 1 figure, Conference Proceedings for Low Radioactivity Techniques 201

The structure of turbulent jets, vortices and boundary layer: Laboratory and field observations

The main aim of this work is research, understand and describe key aspects of the turbulent jets and effects connected with them such as boundary layer interactions or the effect of a 2D geometry. Work is based principally on experiments but there are also some comparisons between experimental and field results. A series of experiments have been performed consisting in detailed turbulent measurements of the 3 velocity components to understand the processes of interaction that lead to mixing and mass transport between boundaries and free shear layers. The turbulent wall jet configuration occurs often in environmental and industrial processes, but here we apply the laboratory experiments as a tool to understand jet/boundary interactions in the environment. We compare the structure of SAR (Synthetic Aperture Radar) images of coastal jets and vortices and experimental jets (plumes) images searching for the relationship between these two kinds of jets at very different Reynolds numbers taking advantage of the self-similarity of the processes. In order to investigate the structure of ocean surface detected jets (SAR) and vortices near the coast, we compare wall and boundary effects on the structure of turbulent jets (3D and 2D) which are non-homogeneous, developing multifractal and spectral techniques useful for environmental monitoring in space

Study of InGaAs based MODFET structures using variable angle spectroscopic ellipsometry

Variable angle spectroscopic ellipsometry was used to estimate the thicknesses of all layers within the optical penetration depth of InGaAs based MODFET structures. Strained and unstrained InGaAs channels were made by MBE on InP substrates and by MOCVD on GaAs substrates. In most cases, ellipsometrically determined thicknesses were within 10 percent of the growth calibration results. The MBE made InGaAs strained layers showed large strain effects, indicating a probable shift in the critical points of their dielectric function toward the InP lattice matched concentration

Multifractal observations of eddies, oil spills and natural slicks in the ocean surface

Natural and man-made distributions of tensioactive substance concentrations in the sea surface features exhibit self-similarity at all radar reflectivity levels when illuminated by SAR. This allows the investigation of the traces produced by vortices and other features in the ocean surface. The man-made oil spills besides often presenting some linear axis of the pollutant concentration produced by moving ships also show their artificial production in the sea surface by the reduced range of scales, which widens as time measured in terms of the local eddy diffusivity distorts the shape of the oil spills. Thanks to this, multifractal analysis of the different backscattered intensity levels in SAR imagery can be used to distinguish between natural and man-made sea surface features due to their distinct self-similar properties. The differences are detected using the multifractal box-counting algorithm on different sets of SAR images giving also information on the age of the spills. Different multifractal algorithms are compared presenting the differences in scaling as a function of some physical generating process such as the locality or the spectral energy cascade

Protein spot arrays on graphene oxide coatings for efficient single-cell capture

Biomedical applications such as cell screening or cell–cell interaction studies require placement and adhesion of cells on surfaces with controlled numbers and location. In particular, single-cell arraying and positioning has come into focus as a basis of such applications. An ideal substrate would combine biocompatibility with favorable attributes such as pattern stability and easy processing. Here, we present a simple yet effective approach to single-cell arraying based on a graphene oxide (GO) surface carrying protein (fibronectin) microarrays to define cell adhesion points. These capture NIH-3T3 cells, resulting in cell arrays, which are benchmarked against analogous arrays on silanized glass samples. We reveal significant improvement in cell-capture performance by the GO coating with regards to overall cell adhesion and single-cell feature occupancy. This overall improvement of cell-arraying combined with retained transparency of substrate for microscopy and good biocompatibility makes this graphene-based approach attractive for single-cell experiments

Hemifacial Spasm and Neurovascular Compression

Hemifacial spasm (HFS) is characterized by involuntary unilateral contractions of the muscles innervated by the ipsilateral facial nerve, usually starting around the eyes before progressing inferiorly to the cheek, mouth, and neck. Its prevalence is 9.8 per 100,000 persons with an average age of onset of 44 years. The accepted pathophysiology of HFS suggests that it is a disease process of the nerve root entry zone of the facial nerve. HFS can be divided into two types: primary and secondary. Primary HFS is triggered by vascular compression whereas secondary HFS comprises all other causes of facial nerve damage. Clinical examination and imaging modalities such as electromyography (EMG) and magnetic resonance imaging (MRI) are useful to differentiate HFS from other facial movement disorders and for intraoperative planning. The standard medical management for HFS is botulinum neurotoxin (BoNT) injections, which provides low-risk but limited symptomatic relief. The only curative treatment for HFS is microvascular decompression (MVD), a surgical intervention that provides lasting symptomatic relief by reducing compression of the facial nerve root. With a low rate of complications such as hearing loss, MVD remains the treatment of choice for HFS patients as intraoperative technique and monitoring continue to improve

Constructing a logistics space: perspectives form the Gulf Cooperation Council

Development plans across the Gulf Cooperation Council emphasise logistical infrastructure as a driver of economic diversification. Investments in maritime ports, roads, rail, airports and logistics cities are transforming the economic geography of the region. This study aims to make visible this neglected aspect of the physical transformation of the Gulf Cooperation Council with a focus on the understudied maritime container ports in Oman and Qatar. Shifting the analysis to emergent maritime logistical infrastructure at a regional level gives insight into the uneven developments within the Gulf Cooperation Council’s integration project. Three key features emerge: (a) a large degree of duplication in maritime port infrastructure across Gulf Cooperation Council states; (b) a regional hierarchy among Gulf Cooperation Council states that are resource rich and those dependent on public–private partnerships and (c) increasing competition among internationally dominant port operators looking to gain access to the Gulf Cooperation Council maritime port market. These features both reflect and reinforce competitive tensions within the regional integration project

Sensitivity of Space Launch System Buffet Forcing Functions to Buffet Mitigation Options

Time-varying buffet forcing functions arise from unsteady aerodynamic pressures and are one of many load environments, which contribute to the overall loading condition of a launch vehicle during ascent through the atmosphere. The buffet environment is typically highest at transonic conditions and can excite the vehicle dynamic modes of vibration. The vehicle response to these buffet forcing functions may cause high structural bending moments and vibratory environments, which can exceed the capabilities of the structure, or of vehicle components such as payloads and avionics. Vehicle configurations, protuberances, payload fairings, and large changes in stage diameter can trigger undesirable buffet environments. The Space Launch System (SLS) multi-body configuration and its structural dynamic characteristics presented challenges to the load cycle design process with respect to buffet-induced loads and responses. An initial wind-tunnel test of a 3-percent scale SLS rigid buffet model was conducted in 2012 and revealed high buffet environments behind the booster forward attachment protuberance, which contributed to reduced vehicle structural margins. Six buffet mitigation options were explored to alleviate the high buffet environments including modified booster nose cones and fences/strakes on the booster and core. These studies led to a second buffet test program that was conducted in 2014 to assess the ability of the buffet mitigation options to reduce buffet environments on the vehicle. This paper will present comparisons of buffet forcing functions from each of the buffet mitigation options tested, with a focus on sectional forcing function rms levels within regions of the vehicle prone to high buffet environments

A New High Channel-Count, High Scan-Rate, Data Acquisition System for the NASA Langley Transonic Dynamics Tunnel

A data acquisition system upgrade project, known as AB-DAS, is underway at the NASA Langley Transonic Dynamics Tunnel. AB-DAS will soon serve as the primary data system and will substantially increase the scan-rate capabilities and analog channel count while maintaining other unique aeroelastic and dynamic test capabilities required of the facility. AB-DAS is configurable, adaptable, and enables buffet and aeroacoustic tests by synchronously scanning all analog channels and recording the high scan-rate time history values for each data quantity. AB-DAS is currently available for use as a stand-alone data system with limited capabilities while development continues. This paper describes AB-DAS, the design methodology, and the current features and capabilities. It also outlines the future work and projected capabilities following completion of the data system upgrade project

Mental, Social and Visual Alienation in D’Alessandro’s Photography

This chapter analyzes the first of several photobooks that illustrated the reform of psychiatric health care in Italy in the 1960s and 1970s: Luciano D’Alessandro’s 1969 Gli esclusi. In 1967, D’Alessandro was invited by the director of the asylum of Nocera Superiore, Sergio Piro, to document through photography the abysmal conditions of the “total institution” that was the pre-reform mental hospital. D’Alessandro first published a small selection of photos, in Popular Photography Italiana (1967), which he then expanded in Gli esclusi. This chapter claims that, in the evolution between the two publications, we can read the complex and multilayered notion of alienation that informed the work of reform, especially that of one of the most famous figures associated with it, Franco Basaglia. By analyzing D’Alessandro’s Gli esclusi through the notion of alienation, this chapter lets what Sekula calls the conditions of “readability” of the photographic message emerge