Emission Ghost Imaging: reconstruction with data augmentation.

Ghost Imaging enables 2D reconstruction of an object even though particles transmitted or emitted by the object of interest are detected with a single pixel detector without spatial resolution. This is possible because for the particular implementation of ghost imaging presented here, the incident beam is spatially modulated with a non-configurable attenuating mask whose orientation is varied (e.g. via transverse displacement or rotation) in the course of the ghost imaging experiment. Each orientation yields a distinct spatial pattern in the attenuated beam. In many cases, ghost imaging reconstructions can be dramatically improved by factoring the measurement matrix which consists of measured attenuated incident radiation for each of many orientations of the mask at each pixel to be reconstructed as the product of an orthonormal matrix Qand an upper triangular matrix R provided that the number of orientations of the mask (N) is greater than or equal to the number of pixels (P) reconstructed. For the N

Disentangling topographic contributions to near-field scanning microwave microscopy images.

We develop empirical models to predict the contribution of topographic variations in a sample to near-field scanning probe microwave microscopy (NSMM) images. In particular, we focus on |S11| images of a thin Perovskite photovoltaic material and a GaN nanowire. The difference between the measured NSMM image and this prediction is our estimate of the contribution of material property variations to the measured image. Prediction model parameters are determined from either a reference sample that is nearly free of material property variations or directly from the sample of interest. The parameters of the prediction model are determined by robust linear regression so as to minimize the effect of material property variations on results. For the case where the parameters are determined from the reference sample, the prediction is adjusted to account for instrument drift effects. Our statistical approach black is fully empirical black and thus complementary to current approaches based on physical models that are often overly simplistic.

A Boltzmann Constant Determination Based on Johnson Noise Thermometry.

A value for the Boltzmann constant was measured electronically using an improved version of the Johnson Noise Thermometry (JNT) system at the National Institute of Standards and Technology (NIST), USA. This system is different from prior ones, including those from the 2011 determination at NIST and both 2015 and 2017 determinations at the National Institute of Metrology (NIM), China. As in all three previous determinations, the main contribution to the combined uncertainty is the statistical uncertainty in the noise measurement, which is mitigated by accumulating and integrating many weeks of cross-correlated measured data. The second major uncertainty contribution also still results from variations in the frequency response of the ratio of the measured spectral noise of the two noise sources, the sense resistor at the triple-point of water and the superconducting quantum voltage noise source. In this paper, we briefly describe the major differences between our JNT system and previous systems, in particular the input circuit and approach we used to match the frequency responses of the two noise sources. After analyzing and integrating 49 days of accumulated data, we determined a value: k = 1.380 642 9(69)×10-23 J/K with a relative standard uncertainty of 5.0×10-6 and relative offset -4.05×10-6 from the CODATA 2014 recommended value.

Preparation of Entangled States through Hilbert Space Engineering.

We apply laser fields to trapped atomic ions to constrain the quantum dynamics from a simultaneously applied global microwave field to an initial product state and a target entangled state. This approach comes under what has become known in the literature as "quantum Zeno dynamics" and we use it to prepare entangled states of two and three ions. With two trapped ^{9}Be^{+} ions, we obtain Bell state fidelities up to 0.990_{-5}^{+2}; with three ions, a W-state fidelity of 0.910_{-7}^{+4} is obtained. Compared to other methods of producing entanglement in trapped ions, this procedure can be relatively insensitive to certain imperfections such as fluctuations in laser intensity.

High-Fidelity Universal Gate Set for

We report high-fidelity laser-beam-induced quantum logic gates on magnetic-field-insensitive qubits comprised of hyperfine states in ^{9}Be^{+} ions with a memory coherence time of more than 1 s. We demonstrate single-qubit gates with an error per gate of 3.8(1)×10^{-5}. By creating a Bell state with a deterministic two-qubit gate, we deduce a gate error of 8(4)×10^{-4}. We characterize the errors in our implementation and discuss methods to further reduce imperfections towards values that are compatible with fault-tolerant processing at realistic overhead.

Precision Measurement of the Radiative ß Decay of the Free Neutron.

The standard model predicts that, in addition to a proton, an electron, and an antineutrino, a continuous spectrum of photons is emitted in the ß decay of the free neutron. We report on the RDK II experiment which measured the photon spectrum using two different detector arrays. An annular array of bismuth germanium oxide scintillators detected photons from 14 to 782 keV. The spectral shape was consistent with theory, and we determined a branching ratio of 0.00335±0.00005[stat]±0.00015[syst]. A second detector array of large area avalanche photodiodes directly detected photons from 0.4 to 14 keV. For this array, the spectral shape was consistent with theory, and the branching ratio was determined to be 0.00582±0.00023[stat]±0.00062[syst]. We report the first precision test of the shape of the photon energy spectrum from neutron radiative decay and a substantially improved determination of the branching ratio over a broad range of photon energies.

Adaptive and robust statistical methods for processing near-field scanning microwave microscopy images.

Near-field scanning microwave microscopy offers great potential to facilitate characterization, development and modeling of materials. By acquiring microwave images at multiple frequencies and amplitudes (along with the other modalities) one can study material and device physics at different lateral and depth scales. Images are typically noisy and contaminated by artifacts that can vary from scan line to scan line and planar-like trends due to sample tilt errors. Here, we level images based on an estimate of a smooth 2-d trend determined with a robust implementation of a local regression method. In this robust approach, features and outliers which are not due to the trend are automatically downweighted. We denoise images with the Adaptive Weights Smoothing method. This method smooths out additive noise while preserving edge-like features in images. We demonstrate the feasibility of our methods on topography images and microwave |S11| images. For one challenging test case, we demonstrate that our method outperforms alternative methods from the scanning probe microscopy data analysis software package Gwyddion. Our methods should be useful for massive image data sets where manual selection of landmarks or image subsets by a user is impractical.

Ventral hernia mesh tack causes liver hemorrhage.

INTRODUCTION: The laparoscopic approach is an increasingly popular option for ventral hernia repair. In the wake of this new technology, unexpected complications have been reported. CASE PRESENTATION: We present the case of a patient who developed a liver laceration and hemorrhage after a mesh tacking device partially dislodged subsequent to ventral hernia repair. The patient underwent exploratory laparotomy, liver hemostasis and removal of the offending tack. DISCUSSION: Our patient partially dislodged a mesh tacking device likely after violent coughing during a bout of pneumonia. The exposed blade caused a liver laceration and hemorrhage. Few other unexpected complications of the use of mesh tacking devices have been noted in the literature. Tackless hernia repair has also been described. CONCLUSION: Laparoscopic ventral hernia repair with tacks may have unexpected complications of which the surgeon should be aware and advise patients. Our patient developed a liver laceration and symptomatic hemorrhage after partially dislodging a hernia mesh tack. Further research into tackless hernia repair may be beneficial. A low long-term recurrence rate would demonstrate if tackless hernia repair is a viable option.

A near-field scanning microwave microscope for characterization of inhomogeneous photovoltaics.

We present a near-field scanning microwave microscope (NSMM) that has been configured for imaging photovoltaic samples. Our system incorporates a Pt-Ir tip inserted into an open-ended coaxial cable to form a weakly coupled resonator, allowing the microwave reflection S(11) signal to be measured across a sample over a frequency range of 1 GHz - 5 GHz. A phase-tuning circuit increased impedance-measurement sensitivity by allowing for tuning of the S(11) minimum down to -78 dBm. A bias-T and preamplifier enabled simultaneous, non-contact measurement of the DC tip-sample current, and a tuning fork feedback system provided simultaneous topographic data. Light-free tuning fork feedback provided characterization of photovoltaic samples both in the dark and under illumination at 405 nm. NSMM measurements were obtained on an inhomogeneous, third-generation Cu(In,Ga)Se(2) (CIGS) sample. The S(11) and DC current features were found to spatially broaden around grain boundaries with the sample under illumination. The broadening is attributed to optically generated charge that becomes trapped and changes the local depletion of the grain boundaries, thereby modifying the local capacitance. Imaging provided by the NSMM offers a new RF methodology to resolve and characterize nanoscale electrical features in photovoltaic materials and devices.

Defective neuromuscular transmission in the SOD1 G93A transgenic mouse improves after administration of human umbilical cord blood cells.

To assess the effect of human umbilical cord blood (hUCB) transplantation on neuromuscular transmission in SOD1(G93A) transgenic mice, we studied the probability of neuromuscular transmission (PNMT), a relevant physiological indicator of motor nerve function, in 3 SOD1(G93A) mice transplanted with hUCB and compared to PNMT in 4 SOD1(G93A) mice without cell transplantation and 3 non-mutant SOD1 transgenic mice. For preparations isolated from non-mutant SOD1 transgenic mice, PNMT was 0.93 and 0.84 during the first 5 s of 70 and 90 Hz trains, respectively. PNMT gradually declined to 0.77 and 0.42 at the end of the trains. In striking contrast, PNMT for preparations from non-treated mutant SOD1(G93A) mice was 0.52 and 0.36 in the first 5 s of 70 and 90 Hz trains, respectively (p<0.05). Treatment with hUCB significantly (p<0.05) improved PNMT in SOD1(G93A) preparations. That is, the initial 5 s PNMT was 0.88 and 0.68 for the 70 and 90 Hz stimuli, respectively. We concluded that hUCB transplantation significantly improved PNMT for muscles removed from SOD1(G93A) mice. Testing PNMT in the SOD1(G93A) mouse model could be used as a simple in vitro protocol to detect a positive cellular response to therapeutic interventions in ALS.

Invited article: development of high-field superconducting Ioffe magnetic traps.

We describe the design, construction, and performance of three generations of superconducting Ioffe magnetic traps. The first two are low current traps, built from four racetrack shaped quadrupole coils and two solenoid assemblies. Coils are wet wound with multifilament NbTi superconducting wires embedded in epoxy matrices. The magnet bore diameters are 51 and 105 mm with identical trap depths of 1.0 T at their operating currents and at 4.2 K. A third trap uses a high current accelerator-type quadrupole magnet and two low current solenoids. This trap has a bore diameter of 140 mm and tested trap depth of 2.8 T. Both low current traps show signs of excessive training. The high current hybrid trap, on the other hand, exhibits good training behavior and is amenable to quench protection.

Recommendations for a technical quality control program for diagnostic X-ray equipment.

This position paper was produced by a working party set up by the Radiology Special Interest Group of the ACPSEM in 2001. It is designed to give the consensus view of College members in Australia and New Zealand on the nature and frequency of tests which should be performed on diagnostic x-ray equipment to maintain adequate quality control of imaging performance and radiation safety. Tests on mammographic equipment have been excluded having been covered in a previous ACPSEM position paper (Australas Phys Eng Sci Med, 24(3):107-131, 2001). Detailed descriptions of test procedures are not given but it is intended that a series of workbooks should be produced giving College recommended test methods for each imaging modality. The recommendations are produced here in an easy-to-read, tabular form giving the nature and purpose of each test and the implications of non-compliance with regard to image quality and radiation safety.

Determination of the Neutron Lifetime Using Magnetically Trapped Neutrons.

We report progress on an experiment to measure the neutron lifetime using magnetically trapped neutrons. Neutrons are loaded into a 1.1 T deep superconducting Ioffe-type trap by scattering 0.89 nm neutrons in isotopically pure superfluid (4)He. Neutron decays are detected in real time using the scintillation light produced in the helium by the beta-decay electrons. The measured trap lifetime at a helium temperature of 300 mK and with no ameliorative magnetic ramping is substantially shorter than the free neutron lifetime. This is attributed to the presence of neutrons with energies higher than the magnetic potential of the trap. Magnetic field ramping is implemented to eliminate these neutrons, resulting in an [Formula: see text] trap lifetime, consistent with the currently accepted value of the free neutron lifetime.

Chaotic Scattering and Escape Times of Marginally Trapped Ultracold Neutrons.

We compute classical trajectories of Ultracold neutrons (UCNs) in a superconducting Ioffe-type magnetic trap using a symplectic integration method. We find that the computed escape time for a particular set of initial conditions (momentum and position) does not generally stabilize as the time step parameter is reduced unless the escape time is short (less than approximately 10 s). For energy intervals where more than half of the escape times computed for UCN realizations are numerically well determined, we predict the median escape time as a function of the midpoint of the interval.

Detecting the Radiative Decay Mode of the Neutron.

Beta decay of the neutron into a proton, electron, and electron antineutrino is occasionally accompanied by the emission of a photon. Despite decades of detailed experimental studies of neutron beta-decay, this rare branch of a fundamental weak decay has never been observed. An experiment to study the radiative beta-decay of the neutron is currently being developed for the NG-6 fundamental physics endstation at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). The experiment will make use of the existing apparatus for the NIST proton-trap lifetime experiment, which can provide substantial background reduction by providing an electron-proton coincidence trigger. Tests and design of a detector for gamma-rays in the 10 keV to 200 keV range are under development. The need for a large solid-angle gamma-ray detector that can operate in a strong magnetic field and at low temperature has led us to consider scintillating crystals in conjunction with avalanche photodiodes. The motivation and experimental technique will be discussed.

CT screening--whole-body and targeted.

At present, the Australasian College of Physical Scientists and Engineers in Medicine does not support the practice of self-referred whole-body CT screening of asymptomatic patients because: The procedure involves a non-trivial radiation dose, which assumes even greater significance in the context of an ongoing screening programme; There is a high likelihood of false positives requiring further intervention with its attendant risks; and There is no proven evidence to date that early detection of life-threatening disease by CT has a significant positive effect on patient outcome. The ACPSEM will continue to monitor scientific studies concerning this procedure.

Recommendations for a mammography quality assurance program.

In 1989 the ACPSEM published a position paper entitled "A Quality Assurance Programme for Mass Screening in Mammography". This paper described test parameters and performance specifications for the equipment related aspects of a mammography quality assurance program. Advice on test equipment selection was also provided. In the intervening period of time there have been considerable advances in mammography technology creating a need to review a number of the paper's recommendations. There have also been considerable developments in the mammography quality assurance (QA) field, not the least of which includes the American College of Radiology Mammography Accreditation Program (ACR-MAP) and the similarly structured Royal Australian and New Zealand College of Radiologists' Mammography Accreditation Program (RANZCR-MAP). In light of these developments it was decided by the Radiology Interest Group to review the ACPSEM position on those aspects of mammography QA that fall within the medical physicist's area of expertise. This document represents the outcome of those deliberations.

Mortality rates and the utilization of health services during terminal illness in the Asaro Valley, Eastern Highlands Province, Papua New Guinea.

Between 1980 and 1989 we carried out fortnightly demographic surveillance in a random sample of people living in Goroka town, periurban areas and rural areas in the Lowa and Asaro Census Divisions, all within 1 1/2 hours' drive of the town in the Asaro Valley, Eastern Highlands Province. Cause of death was determined by verbal autopsy supplemented by any available health service information. Crude death and birth rates were 10 and 32 per 1000 person-years, respectively, in 59,906 person-years at risk. The standardized mortality ratio increased with increasing distance from town. Life expectancy at birth was 57 years for males and 55 years for females. The stillbirth rate was 19 per 1000 births, neonatal and infant mortality 21 and 60 per 1000 livebirths, respectively, and 1-4-year mortality 9 per 1000 person-years. Maternal mortality was 3 per 1000 births. Neonatal and infant mortality were respectively 7 and 3 times as high in Asaro Census Division as in Goroka town. Acute lower respiratory tract infections accounted for 22% of all deaths, chronic obstructive lung disease 10%, trauma 8% and gastroenteritis/dysentery 7%. 76% of deaths occurred at home and 44% of people who died had no treatment during their terminal illness. Health services were used most frequently by urban dwellers and by the young. To reduce mortality, a political commitment to provide functioning health services in rural areas is needed; regular supervision of health staff, ensuring the safety of staff and their families, availability of antibiotics as near people's homes as possible and regular mobile maternal and child health clinics are essential. Health education should include recognition of signs of severe disease and the importance of seeking treatment early. In view of high maternal and neonatal mortality, user fees should be waived for pregnant women.

Shielding properties of fibre cement wallboard.

Transmission data for a fibre cement wallboard (villaboard) are determined for use in diagnostic shielding designs. Villaboard is found to be more attenuating than plasterboard e.g. 9 mm of villaboard is equivalent to 16 mm of plasterboard.

MR appearance of placental site trophoblastic tumor: a report of three cases.

OBJECTIVE: We present the MR imaging appearance of three cases of pathologically proven placental site trophoblastic tumor (PSTT), a potentially malignant but rare form of gestational trophoblastic disease. CONCLUSION: In our series, PSTT presented as myometrial masses that were isointense to healthy myometrium on T1-weighted images and isointense to slightly hyperintense on T2-weighted images. No associated cystic spaces or prominent blood vessels were identified. These MR findings are not specific, and the diagnosis of PSTT is made from biopsy specimen. In two cases, PSTT was invisible sonographically, and accurate localization with MR imaging allowed the patients to be treated with hysterotomy rather than with hysterectomy.