Thermal and Cold Neutron Computed Tomography at the Los Alamos Neutron Scattering Center Using an Amorphous Silicon Detector Array

The use of the EG&G-Heimann RTM 128 [1] or dpiX FS20 [2] amorphous silicon (a-Si) detector array for thermal neutron radiography/computed tomography has proven to be a quick and efficient means of producing high quality digital radiographic images. The resolution, although not as good as film, is about 750 μm with the RTM and 127 μm with the dpiX array with a dynamic range in excess of 2800. In many respects using an amorphous silicon detector is an improvement over other techniques such as imaging with a CCD camera, using a storage phosphor plate or film radiography. Unlike a CCD camera, which is highly susceptible to radiation damage, a-Si detectors can be placed in the beam directly behind the object under examination and do not require any special optics or turning mirrors. The amorphous silicon detector also allows enough data to be acquired to construct a digital image in just a few seconds (minimum gate time 40 ms) whereas film or storage plate exposures can take many minutes and need to be digitized with a scanner. The flat panel can, therefore, acquire a complete 3D computed tomography data set in just a few tens of minutes. While a-Si detectors have been proposed for use in imaging neutron beams [3], this is the first reported implementation of such a detector for neutron imaging [4]

Accident response -- X-ray to virtual environment

The Engineering Sciences and Applications (ESA) Division of Los Alamos National Laboratory (LANL) has been working to develop a process to extract topographical information from digital x-ray data for modeling in a Computer Aided Design (CAD) environment and translation into a virtual environment. The application for this process is the evolution of a field deployable tool for use by the Accident Response Group (ARG) at the Laboratory. The authors have used both CT Scan and radiography data in their process development. The data is translated into a format recognizable by Pro/ENGINEER{trademark} and then into a virtual environment that can be operated on by dVISE{trademark}. They have successfully taken both CT Scan and radiograph data of single components and created solid and virtual environment models for interrogation

Crystal energy functions via the charge in types A and C

The Ram-Yip formula for Macdonald polynomials (at t=0) provides a statistic which we call charge. In types A and C it can be defined on tensor products of Kashiwara-Nakashima single column crystals. In this paper we prove that the charge is equal to the (negative of the) energy function on affine crystals. The algorithm for computing charge is much simpler and can be more efficiently computed than the recursive definition of energy in terms of the combinatorial R-matrix.Comment: 25 pages; 1 figur

Married Black Men’s Opinions as to Why Black Women Are Disproportionately Single: A Qualitative Study

This study’s purpose was to explore the reasons Black women are disproportionately single according to the unique viewpoint of married Black men. The sample comprised 52 married Black men who resided in northeast Georgia (mean age = 43). Qualitative interviews were conducted in 2010 as part of the Pathways to Marriage study. The authors analyzed the data in a collaborative fashion and utilized content analyses to explore the relationships in the data which were derived from qualitative interviews with the men. Findings on the reasons for the disproportionality of singlehood among Black women reflected these four themes: gender relations, marriage education and socialization, individual development, and a preference for gay/lesbian relationships. Recommendations for future research are discussed

Subdiffusion of loci and cytoplasmic particles are different in compressed Escherichia coli cells

The complex physical nature of the bacterial intracellular environment remains largely unknown, and has relevance for key biochemical and biological processes of the cell. Although recent work has addressed the role of non-equilibrium sources of activity and crowding, the consequences of mechanical perturbations are relatively less explored. Here we use a microfabricated valve system to track both fluorescently labeled chromosomal loci and cytoplasmic particles in cells shortly after applying a compressive force, observing the response on time scales that are too sudden to allow for biochemical response from the cell. Cytoplasmic diffusion slows markedly on compression but the exponent governing the growth of the ensemble-averaged mean-squared displacement of cytoplasmic particles is unaffected. In contrast, the corresponding exponent for DNA loci changes significantly. These results suggest that DNA elasticity and nucleoid organization play a more important role in loci subdiffusion than cytoplasmic viscoelasticity under such short time scales

Feasibility of hemoperfusion using extracorporeal therapy in the horse

ObjectiveDevelop, implement, and monitor for adverse effects of, a novel hemoperfusion therapy in adult horses.MethodsA prospective, observational feasibility study using three healthy adult horses from the North Carolina State University teaching herd. Health status was determined by physical exam, complete blood count, coagulation panel, and serum biochemistry. Each horse was instrumented with a 14 Fr × 25 cm double-lumen temporary hemodialysis catheter and underwent a 240 min polymer-based hemoperfusion session. Horses were administered unfractionated heparin to maintain anti-coagulation during the session. Given the novelty of this therapy in horses, each horse was treated as a learning opportunity that informed an iterative process of protocol development and modification.Measurements and main resultsOur long-term goal is to investigate potential clinical applications of hemoperfusion in horses, including cytokine reduction in horses with severe SIRS/sepsis. Horses were monitored for changes in clinical exam, biochemistry and hematology parameters. Additionally, cytokines were quantified to determine whether extracorporeal hemadsorption therapy alone caused an inflammatory response. Our results show that hemoperfusion therapy was associated with decreased platelet counts and serum albumin concentration. There was no significant change in plasma cytokine concentrations with hemoperfusion therapy. In one horse, the cytokine concentrations decreased, as previously reported with hemoperfusion therapy in humans.HypothesisWe hypothesized that hemoperfusion therapy could be performed in healthy adult horses without significant adverse effects.ConclusionPolymer-based hemoperfusion is a feasible extracorporeal therapy (ECT) modality for adult horses. Additional studies are needed to further establish clinical protocols, as well as establish efficacy of polymer-based hemoperfusion for treatment of various conditions in horses, including intoxications, immune-mediated conditions, and sepsis

Graphene Photonics and Optoelectronics

The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. So far, the main focus has been on fundamental physics and electronic devices. However, we believe its true potential to be in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, and the linear dispersion of the Dirac electrons enables ultra-wide-band tunability. The rise of graphene in photonics and optoelectronics is shown by several recent results, ranging from solar cells and light emitting devices, to touch screens, photodetectors and ultrafast lasers. Here we review the state of the art in this emerging field.Comment: Review Nature Photonics, in pres

Ambient fabrication of flexible and large-area organic light-emitting devices using slot-die coating

The grand vision of manufacturing large-area emissive devices with low-cost roll-to-roll coating methods, akin to how newspapers are produced, appeared with the emergence of the organic light-emitting diode about 20 years ago. Today, small organic light-emitting diode displays are commercially available in smartphones, but the promise of a continuous ambient fabrication has unfortunately not materialized yet, as organic light-emitting diodes invariably depend on the use of one or more time- and energy-consuming process steps under vacuum. Here we report an all-solution-based fabrication of an alternative emissive device, a light-emitting electrochemical cell, using a slot-die roll-coating apparatus. The fabricated flexible sheets exhibit bidirectional and uniform light emission, and feature a fault-tolerant >1-μm-thick active material that is doped in situ during operation. It is notable that the initial preparation of inks, the subsequent coating of the constituent layers and the final device operation all could be executed under ambient air