Variable Shadow Screens for Imaging Optical Devices

Variable shadow screens have been proposed for reducing the apparent brightnesses of very bright light sources relative to other sources within the fields of view of diverse imaging optical devices, including video and film cameras and optical devices for imaging directly into the human eye. In other words, variable shadow screens would increase the effective dynamic ranges of such devices. Traditionally, imaging sensors are protected against excessive brightness by use of dark filters and/or reduction of iris diameters. These traditional means do not increase dynamic range; they reduce the ability to view or image dimmer features of an image because they reduce the brightness of all parts of an image by the same factor. On the other hand, a variable shadow screen would darken only the excessively bright parts of an image. For example, dim objects in a field of view that included the setting Sun or bright headlights could be seen more readily in a picture taken through a variable shadow screen than in a picture of the same scene taken through a dark filter or a narrowed iris. The figure depicts one of many potential variations of the basic concept of the variable shadow screen. The shadow screen would be a normally transparent liquid-crystal matrix placed in front of a focal-plane array of photodetectors in a charge-coupled-device video camera. The shadow screen would be placed far enough from the focal plane so as not to disrupt the focal-plane image to an unacceptable degree, yet close enough so that the out-of-focus shadows cast by the screen would still be effective in darkening the brightest parts of the image. The image detected by the photodetector array itself would be used as feedback to drive the variable shadow screen: The video output of the camera would be processed by suitable analog and/or digital electronic circuitry to generate a negative partial version of the image to be impressed on the shadow screen. The parts of the shadow screen in front of those parts of the image with brightness below a specified threshold would be left transparent; the parts of the shadow screen in front of those parts of the image where the brightness exceeded the threshold would be darkened by an amount that would increase with the excess above the threshold

Striatal dopamine D1-type receptor availability: no difference from control but association with cortical thickness in methamphetamine users.

Chronic methamphetamine use poses potentially devastating consequences for directly affected individuals and for society. Lower dopamine D2-type receptor availability has been observed in striata of methamphetamine users as compared with controls, but an analogous comparison of D1-type receptors has been conducted only on post-mortem material, with no differences in methamphetamine users from controls in the caudate nucleus and putamen and higher D1-receptor density in the nucleus accumbens. Released from neurons when methamphetamine is self-administered, dopamine binds to both D1- and D2-type receptors in the striatum, with downstream effects on cortical activity. Thus, both receptor subtypes may contribute to methamphetamine-induced alterations in cortical morphology and behavior. In this study, 21 methamphetamine-dependent subjects and 23 healthy controls participated in positron emission tomography and structural magnetic resonance imaging for assessment of striatal D1- and D2-type receptor availability and cortical gray-matter thickness, respectively. Although D2-type receptor availability (BPnd) was lower in the methamphetamine group, as shown previously, the groups did not differ in D1-type BPnd. In the methamphetamine group, mean cortical gray-matter thickness was negatively associated with cumulative methamphetamine use and craving for the drug. Striatal D1-type but not D2-type BPnd was negatively associated with global mean cortical gray-matter thickness in the methamphetamine group, but no association was found between gray-matter thickness and BPnd for either dopamine receptor subtype in the control group. These results suggest a role of striatal D1-type receptors in cortical adaptation to chronic methamphetamine use

Measurements of Frequency, Temperature, RF Field Dependent Surface Resistance Using Superconducting Half-Wave Cavity

A theory of surface resistance of superconductor was rigorously formulated by Bardeen, Cooper, Schrieffer more than 50 years ago. Since then the accelerator community has been used the theory as a guideline to improve the surface resistance of the superconducting cavity. It has been observed that the surface resistance is dependent on frequency, temperature and rf field strength, and surface preparation. To verify these dependences, a well-controlled study is required. Although many different types of cavities have been tested, the typical superconducting cavities are built for specific frequencies of their application. They do not provide data other than at its own frequency. A superconducting half wave cavity is a cavity that enables us to collect the surface resistance data across frequencies of interest for particle accelerators and evaluate preparation techniques. This paper will present the design of the half wave cavity, its electromagnetic mode characteristics and experimental results

Cryogenic Probe Station at Old Dominion University Center for Accelerator Science

With a growing effort in research and development of an alternative material to bulk Nb for a superconducting radiofrequency (SRF) cavity, it is important to have a cost effective method to benchmark new materials of choice. At Old Dominion University\u27s Center for Accelerator Science, a cryogenic probe station (CPS) will be used to measure the response of superconductor samples under RF fields. The setup consists of a closed-cycle refrigerator for cooling a sample wafer to a cryogenic temperature, a superconducting magnet providing a field parallel to the sample, and DC probes in addition to RF probes. The RF probes will extract a quality factor from a sample patterned in a coplanar waveguide resonator structure on a 2\u27 wafer. From the measured quality factor, the surface resistance and the penetration depth as a function of temperature and magnetic field will be calculated. This paper will discuss the design and measurement procedures of the current CPS setup

Lessons learned from RF-Dipole Prototype Cavities for LHC High Luminosity Upgrade

The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box

Design of a precision calibration unit for Keck NIRC2 AO instrument

High-precision astrometry has the potential to address questions in planet formation, black hole science, Galactic structure, and more. However, in order to achieve a precision of sub-milli arcseconds (mas), we need a calibration method better than the current techniques such as on-sky calibration using calibrated stellar or stellar cluster systems, which have a precision of ~1 mas. Precision calibration unit with a regular grid of photo-lithographically manufactured pinholes combined with self-calibration techniques, on the other hand, is a new and innovative way to potentially achieve a precision of sub-mas over the entire field of view. This technique is beneficial to adaptive optic (AO) instruments for future telescopes like the Thirty Meter Telescope (TMT). In this work, we present our design for a new astrometric calibration unit to feed the NIRC2 AO instrument at the W. M. Keck Observatory. It allows calibration over a large field of view of 47" x 47"

Design of a precision calibration unit for Keck NIRC2 AO instrument

High-precision astrometry has the potential to address questions in planet formation, black hole science, Galactic structure, and more. However, in order to achieve a precision of sub-milli arcseconds (mas), we need a calibration method better than the current techniques such as on-sky calibration using calibrated stellar or stellar cluster systems, which have a precision of ~1 mas. Precision calibration unit with a regular grid of photo-lithographically manufactured pinholes combined with self-calibration techniques, on the other hand, is a new and innovative way to potentially achieve a precision of sub-mas over the entire field of view. This technique is beneficial to adaptive optic (AO) instruments for future telescopes like the Thirty Meter Telescope (TMT). In this work, we present our design for a new astrometric calibration unit to feed the NIRC2 AO instrument at the W. M. Keck Observatory. It allows calibration over a large field of view of 47" x 47"

Clinical value of bioelectrical properties of cancerous tissue in advanced epithelial ovarian cancer patients

Currently, there are no valid pre-operatively established biomarkers or algorithms that can accurately predict surgical and clinical outcome for patients with advanced epithelial ovarian cancer (EOC). In this study, we suggest that profiling of tumour parameters such as bioelectrical-potential and metabolites, detectable by electronic sensors, could facilitate the future development of devices to better monitor disease and predict surgical and treatment outcomes. Biopotential was recorded, using a potentiometric measurement system, in ex vivo paired non-cancerous and cancerous omental tissues from advanced stage EOC (n = 36), and lysates collected for metabolite measurement by microdialysis. Consistently different biopotential values were detected in cancerous tissue versus non-cancerous tissue across all cases (p < 0.001). High tumour biopotential levels correlated with advanced tumour stage (p = 0.048) and tumour load, and negatively correlated with stroma. Within our EOC cohort and specifically the high-grade serous subtype, low biopotential levels associated with poorer progression-free survival (p = 0.0179, p = 0.0143 respectively). Changes in biopotential levels significantly correlated with common apoptosis related pathways. Lactate and glucose levels measured in paired tissues showed significantly higher lactate/glucose ratio in tissues with low biopotential (p < 0.01, n = 12). Our study proposes the feasibility of biopotential and metabolite monitoring as a biomarker modality profiling EOC to predict surgical and clinical outcomes

Impact of Legislated and Best Available Emission Control Measures on UK Particulate Matter Pollution, Premature Mortality, and Nitrogen-Sensitive Habitats

Past emission controls in the UK have substantially reduced precursor emissions of health-hazardous fine particles (PM2.5) and nitrogen pollution detrimental to ecosystems. Still, 79% of the UK exceeds the World Health Organization (WHO) guideline for annual mean PM2.5 of 5 μg m-3 and there is no enforcement of controls on agricultural sources of ammonia (NH3). NH3 is a phytotoxin and an increasingly large contributor to PM2.5 and nitrogen deposited to sensitive habitats. Here we use emissions projections, the GEOS-Chem model, high-resolution data sets, and contemporary exposure-risk relationships to assess potential human and ecosystem health co-benefits in 2030 relative to the present day of adopting legislated or best available emission control measures. We estimate that present-day annual adult premature mortality attributable to exposure to PM2.5 is 48,625 (95% confidence interval: 45,188-52,595), that harmful amounts of reactive nitrogen deposit to almost all (95%) sensitive habitat areas, and that 75% of ambient NH3 exceeds levels safe for bryophytes and lichens. Legal measures decrease the extent of the UK above the WHO guideline to 58% and avoid 6,800 premature deaths by 2030. This improves with best available measures to 36% of the UK and 13,300 avoided deaths. Both legal and best available measures are insufficient at reducing the extent of damage of nitrogen pollution to sensitive habitats. Far more ambitious reductions in nitrogen emissions (>80%) than is achievable with best available measures (34%) are required to halve the amount of excess nitrogen deposited to sensitive habitats