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In this work, we monitor the onset of nonthermal melting in single-crystal silicon by implementing an x-ray pump-x-ray probe scheme. Using the ultrashort pulses provided by the Linac Coherent Light Source (SLAC) and a custom-built split-and-delay line for hard x rays, we achieve the temporal resolution needed to detect the onset of the transition. Our data show no loss of long-range order up to 150±40 fs from photoabsorption, which we interpret as the time needed for the electronic system to equilibrate at or above the critical nonthermal melting temperature. Once such equilibration is reached, the loss of long-range atomic order proceeds inertially and is completed within 315±40 fs from photoabsorption.

Direct measurement of plutonium and uranium X-rays and gamma-rays is a highly desirable non-destructive analysis method for the use in reprocessing fuel environments. The high background and intense radiation from spent fuel make direct measurements difficult to implement since the relatively low activity of uranium and plutonium is masked by the high activity from fission products. To overcome this problem, we make use of a grazing incidence optic to selectively reflect K α and K β fluorescence of Special Nuclear Materials (SNM) into a high-purity position-sensitive germanium detector and obtain their relative ratios.

This article provides an individual perspective on encounters with systemic and family therapy ideas during the transition from university training to professional practice as a Clinical Psychology Registrar. Clinical psychology training provides a solid grounding in individually focussed, cognitive and behavioural models of psychotherapy. What may be less developed on entry to practice are the knowledge, procedural skills and reflective competencies needed to understand and respond to challenges in family-based therapy and in working within complex caregiving systems. Systemic ideas can provide important resources for facilitating these transitions. Trainees may need support not only in gaining knowledge of family therapy models, but also in making a challenging ‘epistemological shift’ (Cullin, 2014) from internalised models of psychopathology to systemic ways of thinking about problems and change. Systemic concepts and support in developing a position of ‘hospitality’ (Larner, 2003) towards competing therapeutic models can also help the trainee be more effective in complex caregiving environments. This article provides examples from my learning as well as reflections on what may help trainees make the transition to professional practice and make use of systemic ideas.

The use of a grazing incidence optic to selectively reflect K-shell fluorescence emission and isotope-specific lines from special nuclear materials is a highly desirable nondestructive analysis method for use in reprocessing fuel environments. Preliminary measurements have been performed, and a simulation suite has been developed to give insight into the design of the x ray optics system as a function of the source emission, multilayer coating characteristics, and general experimental configurations. The experimental results are compared to the predictions from our simulation toolkit to illustrate the ray-tracing capability and explore the effect of modified optics in future measurement campaigns.

Research performed under this LDRD aimed to demonstrate the ability to detect and measure hard X-ray emissions using multilayer X-ray reflective optics above 400 keV, to enable the development of inexpensive and high-accuracy mirror substrates, and to investigate applications of hard X-ray mirrors of interest to the nuclear security community. Experiments conducted at the European Synchrotron Radiation Facility demonstrated hard X-ray mirror reflectivity up to 650 keV for the first time. Hard X-ray optics substrates must have surface roughness under 3 to 4 Angstrom rms, and three materials were evaluated as potential substrates: polycarbonates, thin Schott glass and a new type of flexible glass called Willow Glass®. Chemical smoothing and thermal heating of the surface of polycarbonate samples, which are inexpensive but have poor intrinsic surface characteristics, did not yield acceptable surface roughness. D263 Schott glass was used for the focusing optics of the NASA NuSTAR telescope. The required specialized hardware and process were costly and motivated experiments with a modified non-contact slumping technique. The surface roughness of the glass was preserved and the process yielded cylindrical shells with good net shape pointing to the potential advantage of this technique. Finally, measured surface roughness of 200 and 130 μm thickmore » Willow Glass sheets was between 2 and 2.5 A rms. Additional results of flexibility tests and multilayer deposition campaigns indicated it is a promising substrate for hard X-ray optics. The detection of U and Pu characteristics X-ray lines and gamma emission lines in a high background environment was identified as an area for which X-ray mirrors could have an impact and where focusing optics could help reduce signal to noise ratio by focusing signal onto a smaller detector. Hence the first one twelvetant of a Wolter I focusing optics for the 90 to 140 keV energy range based on aperiodic multilayer coating was designed. Finally, we conducted the first demonstration that reflective multilayer mirrors could be used as diagnostic for HED experiment with an order of magnitude improvement in signal-to-noise ratio for the multilayer optic compared a transmission crystal spectrometer.« less

There is now expert consensus that directly observing the work of trainee therapists vs. relying upon self-report of sessions, is critical to providing the accurate feedback required to attain a range of competencies. In spite of this expert consensus however, and the broadly positive attitudes towards video review among supervisees, video feedback methods remain under-utilized in clinical supervision. This paper outlines some of the weaknesses that affect feedback based solely on self-report methods, before introducing some of the specific benefits that video feedback methods can offer the training and supervision context. It is argued that video feedback methods fit seamlessly into CBT supervision providing direct, accessible, effective, efficient and accurate observation of the learning situation, and optimizing the chances for accurate self-reflections and planning further improvements in performance. To demonstrate the utility of video feedback techniques to CBT supervision, two specific video feedback techniques are introduced and described: the Give-me-5 technique and the I-spy technique. Case examples of CBT supervision using the two techniques are provided and explored, and guidance as to the supervision contexts in which each of the two techniques are suitable, individually, and in tandem, are outlined. Finally, best practice guidelines for the use of video feedback techniques in supervision are outlined.

At the Lawrence Livermore National Laboratory (LLNL) in collaboration with the Linac Coherent Light Source (LCLS) we are developing a mirror-based delay line for x-rays (MEL-X) to enable x-ray pump/x-ray probe experiments at Free Electron Lasers (XFELs). The goal of this project is the development and deployment of a proof-of-principle delay line featuring coated x-ray optics. The four-mirror design of the MEL-X is motivated by the need for ease of alignment and use. In order to simplify the overlap of the pump and the probe beam after each delay time change, a scheme involving super-polished rails and mirror-to-motor decoupling has been adopted. The MEL-X, used in combination with a bright pulsed source like LCLS, features a capability for a high intensity pump beam. Its Iridium coating allows it to work at hard x-ray energies all the way up to 9 keV, with a probe beam transmission of 35% up to 8keV, and 14% at 9keV. The delay time can be tailored to each particular experiment, with a nominal range of 70 - 350 fs for this prototype. The MEL-X, combined with established techniques such as x-ray diffraction, absorption or emission, could provide new insights on ultra-fast transitions in highly excited states of matter.

We report on the design, construction and operation of a low background x-ray detection line composed of a shielded Micromegas (micromesh gaseous structure) detector of the microbulk technique. The detector is made from radiopure materials and is placed at the focal point of a $\sim$~5 cm diameter, 1.3 m focal-length, cone-approximation Wolter I x-ray telescope (XRT) comprised of thermally-formed (or "slumped") glass substrates deposited with multilayer coatings. The system has been conceived as a technological pathfinder for the future International Axion Observatory (IAXO), as it combines two of the techniques (optic and detector) proposed in the conceptual design of the project. It is innovative for two reasons: it is the first time an x-ray optic has been designed and fabricated specifically for axion research, and the first time a Micromegas detector has been operated with an x-ray optic. The line has been installed at one end of the CERN Axion Solar Telescope (CAST) magnet and is currently looking for solar axions. The combination of the XRT and Micromegas detector provides the best signal-to-noise ratio obtained so far by any detection system of the CAST experiment with a background rate of 5.4$\times$10$^{-3}\;$counts per hour in the energy region-of-interest and signal spot area., Comment: 21 pages, 16 figures

Solar axions could be converted into x-rays inside the strong magnetic field of an axion helioscope, triggering the detection of this elusive particle. Low background x-ray detectors are an essential component for the sensitivity of these searches. We report on the latest developments of the Micromegas detectors for the CERN Axion Solar Telescope (CAST), including technological pathfinder activities for the future International Axion Observatory (IAXO). The use of low background techniques and the application of discrimination algorithms based on the high granularity of the readout have led to background levels below 10$^{-6}$ counts/keV/cm$^2$/s, more than a factor 100 lower than the first generation of Micromegas detectors. The best levels achieved at the Canfranc Underground Laboratory (LSC) are as low as 10$^{-7}$ counts/keV/cm$^2$/s, showing good prospects for the application of this technology in IAXO. The current background model, based on underground and surface measurements, is presented, as well as the strategies to further reduce the background level. Finally, we will describe the R&D paths to achieve sub-keV energy thresholds, which could broaden the physics case of axion helioscopes., 6 pages, 3 figures, Large TPC Conference 2014, Paris

Equilibrium contact angles are reported for silicone oils (poly(dimethylsiloxane)s) on polymer-coated and uncoated solid-silicon substrates immersed in aqueous electrolyte solutions. Solid-substrate wettability to water ranges from highly hydrophilic to highly hydrophobic based on water/air contact angles. Although silicone oils in air spread completely on all of the studied substrates, these same surfaces when immersed in aqueous media exhibit finite contact angles against silicone oils that depend strongly on the substrate surface energy. A detailed investigation of the pH influence on the wetting behavior of silicone oil on the solid substrates is pursued where a clear correlation emerges between the changes of substrate-surface zeta potential (ζ) and the oil-wetting behavior on substrates immersed in aqueous solution. Also, the influence of inorganic KCl and CaCl2 electrolytes on the wetting behavior of silicone oils on solid substrates is studied. KCl does not produce a noticeable effect on the wetti...

This study sought to examine oral health beliefs and attitudes, and utilisation of oral health care services among individuals with diabetes and health professionals who serve them in Ghana.A qualitative study using grounded theory was conducted.University of Ghana Dental School at Korle Bu, University of Ghana School of Public Health, National Diabetes Research and Management Centre at Korle Bu, and New York University College of Dentistry.A convenience sample of 59 patients comprised 7 focus groups conducted in either Twi or English. Seven key informant interviews with healthcare professionals and one spiritual leader were completed.Data from the focus groups and interviews reveal: 1, half of the participants with diabetes have oral manifestations (e.g., bleeding gums) and participants are generally unaware of interrelationship between diabetes and oral health; 2, dental treatment utilisation is minimal and associated almost exclusively with reparative and emergency care; and 3, medical health providers do not acknowledge the interrelationship between oral health and diabetes nor do they incorporate oral health issues into diabetes screening/treatment.Oral health knowledge and practices are limited among patients with diabetes in Accra, Ghana. Collaborative efforts for in-service education and training for oral health and medical professionals may be beneficial in serving the oral and general health care needs as well as improving the oral health-related quality of life of Ghanaians with diabetes.

The Kirkpatrick Baez Optic (KBO) diagnostic designed for the National Ignition Facility (NIF) requires very precise alignment between four pairs of mirrors that make up four x-ray imaging channels. Furthermore, the overlapping image axis of the four pairs must be aligned to within a 50 μm radius of the NIF target center. In order to achieve this the diagnostic utilizes a telescoping snout that when extended, locates the mirrors at the end of a Diagnostic Load Package (DLP), cantilevered more than three meters out from its bolted connection points. Discussed in this paper are the structural challenges and the mechanical design solutions that were implemented to achieve the ±50 μm pointing accuracy. During an Inertial Confinement Fusion (ICF) experiment, the KBO diagnostic will be 117 mm away from the extremely high impulse, target implosion shock wave, which requires a unique approach to protecting the sensitive optics which will also be discussed.

At the Lawrence Livermore National Laboratory (LLNL) we have engineered a silicon prototype sample that can be used to reflect focused hard x-ray photons at high intensities in back-scattering geometry.1 Our work is motivated by the need for an all-x-ray pump-and-probe capability at X-ray Free Electron Lasers (XFELs) such as the Linac Coherent Light Source (LCSL) at SLAC. In the first phase of our project, we exposed silicon single crystal to the LCLS beam, and quantitatively studied the x-ray induced damage as a function of x-ray fluence. The damage we observed is extensive at fluences typical of pump-and-probe experiments. The conclusions drawn from our data allowed us to design and manufacture a silicon mirror that can limit the local damage, and reflect the incident beam before its single crystal structure is destroyed. In the second phase of this project we tested this prototype back-reflector at the LCLS. Preliminary results suggest that the new mirror geometry yields reproducible Bragg reflectivity at high x-ray fluences, promising a path forward for silicon single crystals as x-ray back-reflectors.

Bragg mirrors can be used to direct a free-electron laser's x-ray beam onto a sample, but the mirrors are extensively cratered by the intense beam. To create a mirrored surface that is reproducible from one laser shot to the next, the authors in this work lithograph micropillars from a single mirrored crystal of silicon, and demonstrate a strategy whereby each shot of the laser reflects light from one pillar surface, and a fresh micropillar would then be indexed into position for the next shot.

Models of fractally scaled, discrete-component, transmission lines consisting of resistors and capacitors have been investigated experimentally and computationally over extended frequency ranges. Agreement between the predicted performances of the lines and those measured has been found. In particular, a fractional power-law dispersion with frequency, which is a characteristic of scaling, has been observed in the form (, where p is defined by a fixed ratio of the logarithms of the scaling parameters. The effect of localized imperfections on the scaling has been examined by introducing errors into the scaling of the lines and determining the standard deviation of the exponent resulting from these defects. Both for increases and for decreases in magnitude, either of the resistive or of the capacitive elements, the limiting behaviour has been found to be characterized by a square-root dependence of the standard deviation introduced by the imperfection on the magnitude of the relative change in the component from the scaled value. The errors introduced into the dispersions are discussed in terms of the commonly observed fractional power-law response with frequency and the significance of variations from perfect scaling behaviour is discussed.

A semi-infinite, fractally scaled, transmission line is defined in terms of the impedance along the line and the admittance to earth. The relevant Telegrapher's equation has been derived and general and particular solutions have been obtained. The input impedance of the line has been examined as a function of frequency and the voltage development along the lines determined for a range of the scaling parameters. As has been reported for fractal circuits based on discrete components, the input impedance for frequencies less than the inverse of the relaxation time for the line is of a negative fractional power law form in frequency, characteristic of a fractally scaled system, but - uniquely for this case - for frequencies greater than the characteristic value, the input impedance of the inverse of the square root of the frequency response of a non-scaled line is recovered. The conditions under which the fractal line propagates an input signal have been investigated and are reported.

Cellulose fibres and particles in the form of powder, tablets and paper sheets have been investigated by very low frequency dielectric spectroscopy using a novel form of dielectric cell, in which two planar electrodes have been mounted in fixed positions at right angles. The broad pattern of response obtained from the samples is independent of the structural form of the cellulose sample, a loss peak in the 0.1–100 Hz range, and at lower frequencies a dispersion process which is dominated by an imperfect charge transport. Moisture has a significant influence on the rate of charge transport. In dry samples the dipolar loss peak was not evident but as the moisture content increased it appeared. Using a humidity normalizing technique the dielectric response for microcrystalline cellulose has been characterized over the equivalent of 14 decades in frequency. It has also been shown that there is a linear response between the capacitance and the density of microcrystalline cellulose samples. The consolidation of powder into tablets is discussed with respect of the observations of changes in capacitance, loss peak frequency and imperfect charge transport efficiency. Furthermore it was found possible to investigate differences between the dipolar relaxation rate “in” and “out” of the plane of paper in the stack. The relaxation time for dipoles “out” of the paper plane is 7 to 8 times longer than for dipoles “in” the paper plane.

The amounts of fissile Pu and U in spent nuclear fuel are of primary concern to the safeguards community. In particular, there are issues when safeguards transitions from an item accountancy basis (such as fuel bundles) to a fissile material mass basis as occurs when spent fuel enters a reprocessing plant. Discrepancies occur because item accountancy requires estimating the content of fissile material using indirect techniques such as the fuel burn-up and item-level measurements of radiation emissions from fission by-products. Direct measurement of the fissile content by monitoring line emissions from fissile species themselves is impossible because the lines are much weaker than those emitted by shorter-lived isotopes in the fuel. The goal of this project is to develop a technique to directly measure these weaker lines despite the presence of overwhelming radiation from other isotopes. This is achieved by using gamma-ray mirrors as a narrow band-pass filter. The mirrors reflect only energies of interest toward a HPGe detector that is shielded from direct view of the spent fuel and its fierce emissions. This can significantly improve the reliability with which the mass of fissile material is tracked.

At the Lawrence Livermore National Laboratory (LLNL) we are designing, developing and testing multiple Kirkpatrick-Baez (KB) optics to be added to the suite of x-ray diagnostic instruments for the National Ignition Facility (NIF). Each optic consists of four KB channels made of spherically super-polished x-ray substrates. These substrates are multilayer-coated to allow steep grazing angle geometry and wavelength filtering. These optics are customized for different experiments and will provide NIF with an alternative x-ray imaging technique to pinholes, improving both resolution and photon throughput. With this manuscript we describe KB optic requirements, specifications, optical and multilayer designs.

Four lamellar based phases in the lecithin/water/oil phase system have been prepared and examined by low-frequency dielectric spectroscopy in the frequency range 3 × 10 −5 to 3 × 10 +5 Hz. The dielectric properties of the lamellar and liquid crystal phases have been determined over ranges of temperature, and measurements are reported for mixed phase systems. From this information the physical basis for the observed responses has been determined and is reported. Two broad patterns of dielectric response have been found. The ordered micellar and liquid crystal phases do not support dc conductances, even at the lowest frequencies used. The dispersions in these well-defined phases are of the fractional power law form, ( i ω) −s , in frequency with 1 > s > 0.5 at the lowest frequencies and 0.5 > s > 0 in the hertz and kilohertz ranges. On the addition of decane, or by using a formulation that lies close to the lamellar/liquid crystal phase boundary, dc conduction is observed, but in both cases the charge transport is blocked by electrode barrier layers and the generalized Maxwell–Wagner response is found. When the conductance is brought about by the addition of the oil, a large dipolar-like dispersion is observed in the frequency range below the inverse of the bulk relaxation time of the system. This dispersion has been associated with the discrete oil globules within the lamellar structure.

The dielectric response of hydrating cement paste has been measured in the frequency range 5 - Hz. The spectra of complex capacitance have been characterized in terms of the dispersive bulk and barrier responses at high- and low-frequency ranges, respectively, and by a generalized Maxwell - Wagner response at intermediate frequencies. We have developed a theoretical model for the bulk response of the cement paste by considering a lattice gas model for the diffusion of ions in pores exhibiting a fractal distribution in size. Using this model we have assigned physical meanings to parameters characterizing the bulk dielectric response and have determined the variation of these parameters during hydration.

Measurements of the space charge density across the width of a plane parallel sample of degassed crosslinked polyethene (XLPE) have been made recently. Repeated at intervals throughout a period of applied high voltage, these measurements provide data on the dynamics of charge injection and space charge development in the sample under the influence of a stepped high DC voltage. In order to analyse these data, a simple model for bipolar charge injection, subsequent transport and trapping has been developed. This model is reported in this paper, and numerical simulations for charge density generated, as a function of position, time and field, are compared to the experimentally obtained profiles.

The dielectric response of a glass-forming system (Ag2O∶B2O3∶P2O5) has been measured in the frequency range from 10−3–105 Hz and over temperatures in the range 150–400 K for three different compositions. The dynamic behaviour of the conductance and capacitance in these glasses has been observed to follow fractional power-law dependencies on frequency which obey the generalized Maxwell-Wagner relationships. The power-law dispersions for the bulk and the surface layer of the non-ideal solid electrolyte 0.6Ag2O∶xB2O3∶(0.4−x) P2O5 have been modelled mathematically using frequency-dependent resistive and capacitive elements in a conventional equivalent network. It is shown that controlled substitution of B2O3 in the glassy network influences the response and introduces an imperfect charge transport, the quasi-d.c. process of limited charge transport in place of bulk conduction, at higher frequencies, and affects the diffusion barrier at the electrodes to make them, weakly, more conductive at the lowest frequencies. The magnitudes of the activation energies of conduction indicate thermally activated localized hopping of silver ions between neighbouring sites in a structure that is modified by the addition of boron oxide.

High-field electrical breakdown of solid dielectrics is of particular interest to the electricity generation and transmission industries, where the life expectancy of insulation is often uncertain. In order to study and explain the phenomenon a collaborative project has been set up involving National Power, National Grid, King's College London, City of London Polytechnic, Manchester University, Glasgow College of Technology and Bristol University. This paper further develops a time-dependent model of charge injection into a solid dielectric. It explores the quantum mechanics-based theory of how charge crosses from the metal injecting electrode into the dielectric. A current-field relationship is derived, several approximate forms quoted and their limitations discussed. Particular reference is made to an experimental situation for which a curve of injected current versus field is calculated numerically. This is applied to a model of dielectric charge transport and charge distributions are simulated for two experimental geometries.

It is shown that resistance/capacitance transmission lines with multiplicative scaling relationships in the resistive and capacitive elements exhibit a limited range of spectral responses. At high and low frequencies the characteristic impedance of the first, and in a line of finite length the last, elements of the line dominate. In the intermediate frequency range either constant phase angle response or fractional power response may be obtained. The scaling conditions necessary for the observation of these intermediate-frequency responses are established. It is shown that the scaled transmission lines can be considered as fractal when the scaling derives from fractional dimensional properties in continuous media.

A simple microscopic model of an array of water droplets separated by thin oil films is analysed and compared with experimental data from a range of water-in-oil emulsions of high volume fraction in order to delineate the nature of the cooperative effects in such systems. It is shown that a simple summation in series and parallel of the response of isolated particles is fundamentally incapable of giving an acceptable description of the experimental data as is the more complex theoretical model proposed by Hanai. The nature of the corrections to the model are considered from an experimental viewpoint, and the need for a model which is capable of reproducing all the aspects of the experimental situation is discussed.

Many cationic surfactants form, in the presence of certain organic acids, large supramolecular micellar structures in water. The dielectric response of one such system (cetyl trimethyl ammonium bromide-salicylic acid, CTMAS) has been studied as a function of frequency, concentration and temperature. The results are compared with dynamic mechanical data on the same system, which has been published in the literature.

Steady-state space-charge and field distributions in insulators with needle-plane electrodes have been examined theoretically by making use of hyperboloid geometry and a relaxed version of Deutsch's assumption. An analytical solution has been obtained for the conventional space-charge boundary condition of infinite charge and zero field at the surface of the charge injecting needle contact. This solution has been extended to cover a range of injection boundary conditions of both space charge and electrical field magnitudes. It has been found that, in the bulk of the material, the forms of the space charge and field distributions are relatively insensitive to the injection conditions. The distribution of power density dissipated under complete space-charge limited current flow is reported and it has been found that a maximum in the power occurs close to, but not at, the needle tip.

Collisions with rare-gas atoms are observed to produce a lengthening of the lifetime of the highly excited ($n=5\ensuremath{-}10$) $d$ states of Na. The effect is interpreted as collisional angular momentum mixing of the $d$ state with $lg2$ states; thus the average lifetime of all states for which $lg~2$ is observed. The cross section for the process appears to increase as the geometrical cross section of the excited atom.

Dielectric spectroscopical investigation of an oil in water emulsion in the frequency range from mHz to kHz has shown that the response below about 1 Hz is dominated by the physical barriers formed by the lecithin emulsifier whereas the aqueous bulk properties of the emulsion control the response above 1 Hz. Unlike the more complex gel systems already examined using this technique the ac response of the emulsion can be characterized by only five physical parameters, i.e., a high-frequency ac conductance in parallel with a capacitance, the magnitude and fractional power law exponent of the barrier capacitance, and the barrier leakage conductance. This has allowed semi-quantitative assessment of the roles of the individual constituents of the emulsion and the effect of introducing a substituted phenol to the system. The technique has been found particularly useful in observing the stability of the system to both temperature cycling through the freezing point and exposure to air.

A theoretical model is proposed to explain the statistics of electrical tree inception based on the geometry of the initiating electrode and the field variation around its surface. Numerical calculations show that the model is sufficient to describe qualitatively the observed features of both the time to inception distribution and the distribution of inception voltages (fields) obtained in ramp experiments. The implications of the model for the analysis of such experiments are discussed. >

A low background Micromegas X-ray detector has been used to search for solar axions in the CAST experiment at CERN. The detector has an active area of 7cm times 7cm, excellent spatial resolution (~70nm), and good energy resolution. It is built using low radioactivity materials and the obtained background level is below 5times10-5 counts/keV/cm2/s. The detector is being upgraded for the second phase of the experiment (2006-2007) with a reduced active area. A focusing X-Ray optic and improved shielding will be used to further reduce the background by approximately two orders of magnitude.

A low background Micromegas detector has been operating on the CAST experiment at CERN for the search of solar axions during the first phase of the experiment (2002-2004). The detector operated efficiently and achieved a very low level of background rejection ($5\times 10^{-5}$ counts keV$^{-1}$cm$^{-2}$s$^{-1}$) thanks to its good spatial and energy resolution as well as the low radioactivity materials used in the construction of the detector. For the second phase of the experiment (2005-2007), the detector will be upgraded by adding a shielding and including focusing optics. These improvements should allow for a background rejection better than two orders of magnitude., 6 pages, 3 figures To appear on the proceedings of the 9th ICATPP Conference on AStroparticle, Particle, Space Physics, Detectors and Medical Physics Applications

Significant effort currently is being devoted to the development of noninvasive imaging systems that allow in vivo assessment of biological and biomolecular interactions in mice and other small animals. While physiological function in small animals can be localized and imaged using conventional radionuclide imaging techniques such as single-photon emission tomography (SPECT) and positron emission tomography (PET), these techniques inherently are limited to spatial resolutions of 1-2 mm. For this reason, we are developing a small animal radionuclide imaging system (SARIS) using grazing incidence optics to focus gamma-rays emitted by 125I and other radiopharmaceuticals. We have developed a prototype optic with sufficient accuracy and precision to focus the 27.5 keV photons from 125I onto a high-resolution imaging detector. Experimental measurements from the prototype have demonstrated that the optic can focus X-rays from a microfocus X-ray tube to a spot having physical dimensions (approximately 1500 microns half-power diameter) consistent with those predicted by theory. Our theoretical and numerical analysis also indicate that an optic can be designed and build that ultimately can achieve 100 μm spatial resolution with sufficient efficiency to perform it in vivo single photon emission imaging studies in small animal.

A multilayer-based optic was tested for use as an X-ray diagnostic on a laser-plasma experiment. The multilayer optic was employed to selectively pass X-rays between 55 and 100 keV. An order of magnitude improvement in signal-to-noise ratio is achieved compared to a transmission crystal spectrometer. A multilayer response model, taking into account the source size and spectral content, is constructed and the outlook for application above 500 keV is briefly discussed. LLNL-JRNL-664311.

We reviewed 286 consecutive patients with a fracture of a pubic ramus. The overall incidence was 6.9/100,000/year in the total population and 25.6/100,000/year in individuals aged over 60 years. The mean age of the patients was 74.7 years and 24.5% suffered from dementia. Women were affected 4.2 times more often than men. After injury, geriatric rehabilitation was frequently required and although most surviving patients returned to their original place of residence, their level of mobility was often worse. The overall survival rates at one and five years were 86.7% and 45.6%, respectively. Multiple logistic regression analysis showed that age and dementia were the only independent significant factors to be predictive of mortality (p0.05). Patients with a fracture of a pubic ramus had a significantly worse survival than an age-matched cohort from the general population (log-rank test, p0.001), but this was better than patients with a fracture of the hip during the first year after injury, although their subsequent mortality was higher. Five years after the fracture there was no significant difference in survival between the two groups.

Interferometric methods have considerable potential for studying the thickness of layers of the human tear film and cornea because of their ability to make noninvasive, accurate, and rapid measurements. However, previous interferometric studies by Prydal and Danjo yielded tear thickness values near 40 and 11 microm, respectively, considerably greater than estimates made by invasive methods of 4 to 8 microm. Using a modified version of Danjo's method, interference effects from the tear film and cornea were studied, with the aim of correlation with known structure and optical properties of the cornea and hence determining the most probable value of tear film thickness.Reflectance spectra from the human cornea were measured at normal incidence. These spectra show oscillations whose maxima correspond to constructive interference between light reflected from the air surface and from some deeper surface. The frequency of these spectral oscillations is proportional to the thickness of the layer between the air surface and the second surface. Therefore, Fourier analysis of reflectance spectra can be used to determine the thickness of layers of the tear film and cornea. In the main experiment, 36 low-resolution spectra were obtained from six normal eyes for measuring thickness up to 100 microm. Control experiments included measurements of the time course of thickness changes and high-resolution spectra for measuring thickness up to 1000 microm.For the main experiment, in the thickness range 1 to 100 microm, the strongest peak in the Fourier transform was near 3 microm (range, 1.5-4.7 microm) beneath the air surface. In the range 20 to 100 microm, the strongest peak was near 55 microm (range, 50-59 microm) for all 36 spectra; none were in Prydal's range near 40 microm. This 55-microm peak is consistent with a reflection from the basement membrane of the epithelium. Time course measurements after a blink show that the 3-microm peak is not an artifact. High-resolution spectra gave a peak near 510 microm, corresponding to the complete thickness of the cornea (plus tear film). This peak had a contrast similar to that of the 3-microm peak.These studies did not confirm Prydal's estimate of approximately 40 microm. Nor were there prominent peaks near Danjo's value of approximately 11 microm, except in cases of probable reflex tears. Because the reflection at the aqueous-mucus boundary would be expected to be weaker than that from the epithelial surface, the 3-microm peak is unlikely to correspond to the aqueous layer (rather than the complete tear film). The proposal that the 3-microm peak corresponds to a reflection from the front of the cornea is supported by the demonstration of a peak of similar contrast from the back of the cornea. Thus, the current evidence consistently supports a value of approximately 3 microm for the thickness of the human precorneal tear film.

While the environment of the naturally closed eye substantially challenges the oxygen-dependent processes of the cornea, the presence of a contact lens further exacerbates those stresses. The purposes of this study are: (1) to describe responses of the human cornea under closed eye conditions to a wide range of Dk/t environments as ratios of their corresponding normal, open-eye (physiological) baseline rates; (2) to describe the difference ("hypoxic gap") function that separates those closed-eye responses from parallel responses for the open eye; and (3) to present predictive models for all three (closed-eye, open-eye, and difference) response functions in both graphical and mathematical forms.Oxygen uptake rates were measured polarographically: for the normal open eye and after both closed- and open-eye wear of six rigid contact lenses of transmissibilities ranging from 0 to 91 x 10(-9) (cm/sec)(ml O2/ml mmHg).Responses from the closed-eye and open-eye series to those six Dk/t levels were compared both graphically and statistically. Those response series were described by best-fit equations, from which a model for Dk/t effectiveness in meeting corneal oxygen needs under both closed- and open-eye conditions was developed.Response series for both closed and open eyes were found to be well described by natural log equations (R2 values0.99). Statistically, separation of those two series could be demonstrated (p0.05) by the Dk/t level of 12.8 x 10(-9) (cm/sec)(ml O2/ml mmHg). While, by the highest Dk/t level observed here of 91 x 10(-9) (cm/sec)(ml O2/ml mmHg), corneal responses for the open eye have already moderated down to just 1.5x the "ideal standard," closed-eye response rates are still averaging 2.7x that baseline. The difference ("hypoxic gap") function remaining between those closed- and open-eye curves appears to be stabilizing in its magnitude by 91 x 10(-9) (cm/sec)(ml O2/ml mmHg) as well.

Two cDNAs encoding the serine protease inhibitor (serpin) neuroserpin were cloned from a rat pituitary cDNA library (rNS-1, 2922 bp; rNS-2, 1599 bp). In situ hybridization histochemistry showed neuroserpin transcripts in the intermediate, anterior and posterior lobes of the pituitary gland and medullary cells in the adrenal gland. Expression of rNS-1 mRNA was restricted to selected cells in the pituitary gland. Analysis of purified secretory-granule fractions from pituitary and adrenal tissues indicated that neuroserpin was found in dense-cored secretory granules. This result suggested that endocrine neuroserpin may regulate intragranular proteases or inhibit enzymes following regulated secretion. To investigate the function of neuroserpin in endocrine tissues we established stable anterior pituitary AtT-20 cell lines expressing neuroserpin. Cells with increased levels of neuroserpin responded by extending neurite-like processes. Extracellular proteolysis by serine protease plasminogen activators has been suggested to regulate neurite outgrowth. As neuroserpin inhibits tissue plasminogen activator (tPA) in vitro, we measured plasminogen-activator levels. Zymographic analysis indicated that AtT-20 cells synthesized and secreted a plasminogen activator identical in size to tPA. A higher-molecular-mass tPA-neuroserpin complex was also observed in AtT-20-cell conditioned culture medium. tPA levels were similar in parent AtT-20 cells and a stable cell line with increased levels of neuroserpin. There was no accumulation of a tPA-neuroserpin complex. Together these results identify endocrine cells as an important source of neuroserpin. Moreover they suggest that neuroserpin is released from dense-cored secretory granules to regulate cell-extracellular matrix interactions through a mechanism that may not directly involve tPA.

The use of blocking layers of insulators to remove leakage current during measurement of the capacitive properties of coatings is examined both theoretically and experimentally. It is shown that in the case of vinyl emulsion films the 'leakage' is an inherent component of the response and its blocking results in a Maxwell-Wagner response with a peak in the loss component, which can be interpreted as due to charge dipoles. Furthermore, it is shown that a Cole-Cole dispersion results when the response of the film is of a power law form in the region of the Maxwell-Wagner peak loss.

A bifocal rigid gas permeable (RGP) contact lens is now available that totally encapsulates an add segment of a different material within its inferior aspect. The purposes of this study were to determine the effects of the major lens and of its encapsulated segment region on the oxygen uptake rates of underlying cornea.Corneal oxygen uptake rates of 10 human corneas were measured--both centrally and inferiorly--for non-wearing conditions and then immediately after 300-second wearing periods of a polymethylmethacrylate (PMMA) lens and of this RGP-encapsulated segment bifocal contact lens. Corneal responses associated with these three environmental conditions were compared statistically (i.e., without the influence of blink-driven tear flow).Under the nonblinking conditions maintained (i.e., with oxygen availability restricted to lens transmissibility alone), central corneal hypoxia was found for the RGP bifocal lens to be only 47% of that induced by the PMMA (Dk/L = 0) condition, while the cornea under the encapsulated segment of the bifocal lens averaged 78% of the hypoxic response induced by that same condition. Central site responses were found to be significantly different for the bifocal and the PMMA lens (p0.001), as they were for the two inferior sites with these two lenses (p0.001). All lens-related responses were found to be significantly different from the no lens condition (p0.001).Using Smith's model (JAOA, 1997) to estimate lens transmissibility, the major lens of this RGP bifocal design appears to meet approximately 80% of the Holden-Mertz daily-wear oxygen requirement--even without post-lens tear exchange, but only about 25% of that requirement appears to be met beneath the encapsulated segment region. Efficient supplementary infusion of oxygen under this lens by blink-driven tear exchange, then, is necessary to maintain optimal corneal health.