Dystonic reaction to perphenazine (Trilafon)

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Bilharzial granuloma of the spinal cord

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Characterization of room temperature AlGaAs soft X-ray mesa photodiodes

Results characterising a set of nine prototype Al0.8Ga0.2As p+–i–n+ mesa photodiodes (400 µm diameter, 1.7 µm i layer) are presented. The results show the performance of the devices as room temperature spectroscopic photon counting soft X-ray detectors. The responses of the photodiodes to illumination with an 55Fe radioisotope X-ray source were measured using a low noise charge sensitive preamplifier; the energy resolutions measured with the devices were consistent with each other and had a mean FWHM at 5.9 keV of 1.27 keV. The devices are the thickest (highest detection efficiency) AlGaAs X-ray spectroscopic mesa photodiodes reported in the literature to date. They also have better energy resolution than all previously reported non-avalanche AlGaAs X-ray detectors of the same area

Retrodiction of Generalised Measurement Outcomes

If a generalised measurement is performed on a quantum system and we do not know the outcome, are we able to retrodict it with a second measurement? We obtain a necessary and sufficient condition for perfect retrodiction of the outcome of a known generalised measurement, given the final state, for an arbitrary initial state. From this, we deduce that, when the input and output Hilbert spaces have equal (finite) dimension, it is impossible to perfectly retrodict the outcome of any fine-grained measurement (where each POVM element corresponds to a single Kraus operator) for all initial states unless the measurement is unitarily equivalent to a projective measurement. It also enables us to show that every POVM can be realised in such a way that perfect outcome retrodiction is possible for an arbitrary initial state when the number of outcomes does not exceed the output Hilbert space dimension. We then consider the situation where the initial state is not arbitrary, though it may be entangled, and describe the conditions under which unambiguous outcome retrodiction is possible for a fine-grained generalised measurement. We find that this is possible for some state if the Kraus operators are linearly independent. This condition is also necessary when the Kraus operators are non-singular. From this, we deduce that every trace-preserving quantum operation is associated with a generalised measurement whose outcome is unambiguously retrodictable for some initial state, and also that a set of unitary operators can be unambiguously discriminated iff they are linearly independent. We then examine the issue of unambiguous outcome retrodiction without entanglement. This has important connections with the theory of locally linearly dependent and locally linearly independent operators.Comment: To appear in Physical Review

Quantum Copying: Beyond the No-Cloning Theorem

We analyze to what extent it is possible to copy arbitrary states of a two-level quantum system. We show that there exists a "universal quantum copying machine", which approximately copies quantum mechanical states in such a way that the quality of its output does not depend on the input. We also examine a machine which combines a unitary transformation with a selective measurement to produce good copies of states in a neighborhood of a particular state. We discuss the problem of measurement of the output states.Comment: RevTex, 26 pages, to appear in Physical Review

Soft X-ray detection and photon counting spectroscopy with commercial 4H-SiC Schottky photodiodes

The results of electrical characterisation and X-ray detection measurements of two different active area (0.06 mm2 and 0.5 mm2) commercial 4H-SiC Schottky photodiodes at room temperature are reported. The devices exhibited low dark currents (less than 10 pA) even at a high electric field strengths (403 kV/cm for 0.06 mm2 diodes; 227 kV/cm for 0.5 mm2 diodes). The results of the X-ray measurements indicate that the diodes can be used as photon counting spectroscopic X-ray detectors with modest energy resolutions: FWHM at 5.9 keV of 1.8 keV and 3.3 keV, for the 0.06 mm2 and 0.5 mm2 devices, respectively. Noise analysis of the photodiodes coupled to a custom low noise charge sensitive preamplifier is also presented

Al0.2Ga0.8As X-ray photodiodes for X-ray spectroscopy

Three custom-made Al0.2Ga0.8As p-i-n mesa X-ray photodiodes (200 µm diameter, 3 µm i layer) were electrically characterised and investigated for their response to illumination with soft X-rays from an 55Fe radioisotope X-ray source (Mn Kα = 5.9 keV; Mn Kβ = 6.49 keV). The AlGaAs photodiodes were shown to be suitable for photon counting X-ray spectroscopy at room temperature. When coupled to a custom-made low-noise charge-sensitive preamplifier, a mean energy resolution (as quantified by the full width at half maximum of the 5.9 keV photopeak) of 1.24 keV was measured at room temperature. Parameters such as the depletion width (1.92 µm at 10 V), charge trapping noise (61.7 e− rms ENC at 5 V, negligible at 10 V) and the electronic noise components (known dielectric noise (63.4 e− rms), series white noise (27.7 e− rms), parallel white noise (9.5 e− rms) and 1/f series noise (2.2 e− rms) at 10 V reverse bias) affecting the achieved energy resolution were computed. The estimated charge trapping noise and mean energy resolution were compared to similar materials (e.g. Al0.8Ga0.2As) previously reported, and discussed. These results are the first demonstration of photon counting X-ray spectroscopy with Al0.2Ga0.8As reported to date

Characterization of gallium arsenide X-ray mesa p-i-n photodiodes at room temperature

Two GaAs mesa p+-i-n+ photodiodes intended for photon counting X-ray spectroscopy, having an i layer thickness of 7 μm and diameter of 200 μm, have been characterized electrically, for their responsivity at the wavelength range 580 nm to 980 nm and one of them for its performance at detection of soft X-rays, at room temperature. Dark current and capacitance measurements as a function of applied forward and reverse bias are presented. The results show low leakage current densities, in the range of nA/cm2 at the maximum internal electric field (22 kV/cm). The unintentional doping concentration of the i layer, calculated from capacitance measurements, was found to be <1014 cm−3. Photocurrent measurements were performed under visible and near infrared light illumination for both diodes. The analysis of these measurements suggests the presence of a non-active (dead) layer (0.16 μm thickness) at the p+ side top contact interface, where the photogenerated carriers do not contribute to the photocurrent, possibly due to recombination. One of the diodes, D1, was also characterized as detector for room temperature photon counting X-ray spectroscopy; the best energy resolution achieved (FWHM) at 5.9 keV was 745 eV. The noise analysis of the system, based on spectra obtained at different shaping times and applied reverse biases, showed that the dominant source of noise is the dielectric noise. It was also calculated that there was at least (165±24) eV charge trapping noise at 0 V

Gallium Arsenide detectors for X-ray and electron (beta particle) spectroscopy

Results characterizing GaAs p+-i-n+ mesa photodiodes with a 10 µm i layer for their spectral response under illumination of X-rays and beta particles are presented. A total of 22 devices, having diameters of 200 µm and 400 µm, were electrically characterized at room temperature. All devices showed comparable characteristics with a measured leakage current ranging from 4 nA/cm2 to 67 nA/cm2 at an internal electric field of 50 kV/cm. Their unintentionally doped i layers were found to be almost fully depleted at 0 V due to their low doping density. 55Fe X-ray spectra were obtained using one 200 µm diameter device and one 400 µm diameter device. The best energy resolution (FWHM at 5.9 keV) achieved was 625 eV using the 200 µm and 740 eV using the 400 µm diameter device, respectively. Noise analysis showed that the limiting factor for the energy resolution of the system was the dielectric noise; if this noise was eliminated by better design of the front end of the readout electronics, the achievable resolution would be 250 eV. 63Ni beta particle spectra obtained using the 200 µm diameter device showed the potential utility of these detectors for electron and beta particle detection. The development of semiconductor electron spectrometers is important particularly for space plasma physics; such devices may find use in future space missions to study the plasma environment of Jupiter and Europa and the predicted electron impact excitation of water vapor plumes from Europa hypothesized as a result of recent Hubble Space Telescope (HST) UV observations

Pictorial scale of perceived water competence (PSPWC) testing manual

The Early Years Special Interest Group have completed a technical publication, ‘Pictorial Scale of Perceived Water Competence (PSPWC) Testing Manual’. This publication is the first to specifically focus and develop an assessment tool appropriate for young children aged 4 – 8 years old. It aims to address the following specific needs 1) to be accessible to this young age range, 2) to be suitable for children of different swimming levels, 3) cover all the aquatic fundamentals – water entry, breath control, buoyancy, balance, propulsion, immersion, water exit, gliding and vision. The idea to develop the PSPWC started during the Early Years Special Interest Group meeting at Laramie 2016 AIESEP, which then developed into a larger group of experts in order to develop and present the assessment tool. A four year process of critical analysis, preliminary face-validity, face-validity and content validity were completed in the development of each version of the PSPWC until the final testing manual was completed. Within the testing manual all aquatic skills and test items are represented through visual methodologies of drawings by a professional illustrator. In order to engage young children’s interests and to keep their attention to facilitate their understanding and to obtain more meaningful responses. The testing manual includes 3 level progressions for each situation, skill or test item, level 1 = “not able to do the skill”; level 2 = “skill in progress” and level 3 = “able to do the skill. The 3 level progression was developed as the expert group considered it more appropriate to have a process orientated scale showing a child’s developmental progression. The PSPWC can be applied for use in children (measurement of their own perceived water competence), in parents (measurements of their perception of children’s water competence) and/or in teachers (measurement of their perception of pupils’ / students’ water competence. The testing manual is accessible to all through open access publication