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J A Dávila-Pintle, E Reynoso-Lara, Y E Bravo-García
This paper reports an improvement to the chopper z-scan technique for elliptic Gaussian beams. This improvement results in a higher sensitivity by measuring the ratio of eclipsing time to rotating period (duty cycle) of a chopper that eclipses the beam along the main axis. It is shown that the z-scan curve of the major axis is compressed along the z-axis. This compression factor is equal to the ratio between the minor and major axes. It was found that the normalized peak-valley difference with respect to the linear value does not depend on the axis along which eclipsing occurs...
September 5, 2016: Optics Express
N Tsapatsaris, R E Lechner, M Markó, H N Bordallo
In this work, we present the conceptual design of the backscattering time-of-flight spectrometer MIRACLES approved for construction at the long-pulse European Spallation Source (ESS). MIRACLES's unparalleled combination of variable resolution, high flux, extended energy, and momentum transfer (0.2-6 Å(-1)) ranges will open new avenues for neutron backscattering spectroscopy. Its remarkable flexibility can be attributed to 3 key elements: the long-pulse time structure and low repetition rate of the ESS neutron source, the chopper cascade that tailors the moderator pulse in the primary part of the spectrometer, and the bent Si(111) analyzer crystals arranged in a near-backscattering geometry in the secondary part of the spectrometer...
August 2016: Review of Scientific Instruments
Eric M Dufresne, Robert W Dunford, Elliot P Kanter, Yuan Gao, Seoksu Moon, Donald A Walko, Xusheng Zhang
The performance of a cooled Be compound refractive lens (CRL) has been tested at the Advanced Photon Source (APS) to enable vertical focusing of the pink beam and permit the X-ray beam to spatially overlap with an 80 µm-high low-density plasma that simulates astrophysical environments. Focusing the fundamental harmonics of an insertion device white beam increases the APS power density; here, a power density as high as 500 W mm(-2) was calculated. A CRL is chromatic so it does not efficiently focus X-rays whose energies are above the fundamental...
September 1, 2016: Journal of Synchrotron Radiation
Katalin Kristó, Orsolya Kovács, András Kelemen, Ferenc Lajkó, Gábor Klivényi, Béla Jancsik, Klára Pintye-Hódi, Géza Regdon
In the literature there are some publications about the effect of impeller and chopper speeds on product parameters. However, there is no information about the effect of temperature. Therefore our main aim was the investigation of elevated temperature and temperature distribution during pelletization in a high shear granulator according to process analytical technology. During our experimental work, pellets containing pepsin were formulated with a high-shear granulator. A specially designed chamber (Opulus Ltd...
August 27, 2016: European Journal of Pharmaceutical Sciences
Tian Li, Brian E Anderson, Travis Horrom, Kevin M Jones, Paul D Lett
Many optical applications depend on amplitude modulating optical beams using devices such as acousto-optical modulators (AOMs) or optical choppers. Methods to add amplitude modulation (AM) often inadvertently impart phase modulation (PM) onto the light as well. While this PM is of no consequence to many phase-insensitive applications, phase-sensitive processes can be affected. Here we study the effects of input phase and amplitude modulation on the output of a quantum-noise limited phase-sensitive optical amplifier (PSA) realized in hot <sup>85</sup>Rb vapor...
August 22, 2016: Optics Express
Liang Guo, Daniele M Monahan, Graham Fleming
Spectrometers and cameras are used in ultrafast spectroscopy to achieve high resolution in both time and frequency domains. Frequency-resolved signals from the camera pixels cannot be processed by common lock-in amplifiers, which have only a limited number of input channels. Here we demonstrate a rapid and economical method that achieves the function of a lock-in amplifier using mechanical choppers and a programmable microcontroller. We demonstrate the method's effectiveness by performing a frequency-resolved pump-probe measurement on the dye Nile Blue in solution...
August 8, 2016: Optics Express
S K Patch, M Kireeff Covo, A Jackson, Y M Qadadha, K S Campbell, R A Albright, P Bloemhard, A P Donoghue, C R Siero, T L Gimpel, S M Small, B F Ninemire, M B Johnson, L Phair
The potential of particle therapy due to focused dose deposition in the Bragg peak has not yet been fully realized due to inaccuracies in range verification. The purpose of this work was to correlate the Bragg peak location with target structure, by overlaying the location of the Bragg peak onto a standard ultrasound image. Pulsed delivery of 50 MeV protons was accomplished by a fast chopper installed between the ion source and the cyclotron inflector. The chopper limited the train of bunches so that 2 Gy were delivered in [Formula: see text]...
August 7, 2016: Physics in Medicine and Biology
Anna Fedrigo, Daniele Colognesi, Mads Bertelsen, Monika Hartl, Kim Lefmann, Pascale P Deen, Markus Strobl, Francesco Grazzi, Marco Zoppi
VESPA, Vibrational Excitation Spectrometer with Pyrolytic-graphite Analysers, aims to probe molecular excitations via inelastic neutron scattering. It is a thermal high resolution inverted geometry time-of-flight instrument designed to maximise the use of the long pulse of the European Spallation Source. The wavelength frame multiplication technique was applied to provide simultaneously a broad dynamic range (about 0-500 meV) while a system of optical blind choppers allows to trade flux for energy resolution...
June 2016: Review of Scientific Instruments
Arezu Bagheri, Muhammad Tariqus Salam, Jose Luis Perez Velazquez, Roman Genov
We review integrated circuits for low-frequency noise and offset rejection as a motivation for the presented digitally-assisted neural amplifier design methodology. Conventional AC-coupled neural amplifiers inherently reject input DC offset but have key limitations in area, linearity, DC drift, and spectral accuracy. Their chopper stabilization reduces low-frequency intrinsic noise at the cost of degraded area, input impedance and design complexity. DC-coupled implementations with digital high-pass filtering yield improved area, linearity, drift, and spectral accuracy and are inherently suitable for simple chopper stabilization...
June 10, 2016: IEEE Transactions on Biomedical Circuits and Systems
Ken Smart, Jia Du, Li Li, David Wang, Keith Leslie, Fan Ji, Xiang Dong Li, Da Zhang Zeng
A practical compact solid-state terahertz imaging system is presented. Various beam guiding architectures were explored and hardware performance assessed to improve its compactness, robustness, multi-functionality and simplicity of operation. The system performance in terms of image resolution, signal-to-noise ratio, the electronic signal modulation versus optical chopper, is evaluated and discussed. The system can be conveniently switched between transmission and reflection mode according to the application...
2016: Sensors
Justus Koerfer, Sonja Kallendrusch, Felicitas Merz, Christian Wittekind, Christoph Kubick, Woubet T Kassahun, Guido Schumacher, Christian Moebius, Nikolaus Gaßler, Nikolas Schopow, Daniela Geister, Volker Wiechmann, Arved Weimann, Christian Eckmann, Achim Aigner, Ingo Bechmann, Florian Lordick
Gastric and esophagogastric junction cancers are heterogeneous and aggressive tumors with an unpredictable response to cytotoxic treatment. New methods allowing for the analysis of drug resistance are needed. Here, we describe a novel technique by which human tumor specimens can be cultured ex vivo, preserving parts of the natural cancer microenvironment. Using a tissue chopper, fresh surgical tissue samples were cut in 400 μm slices and cultivated in 6-well plates for up to 6 days. The slices were processed for routine histopathology and immunohistochemistry...
July 2016: Cancer Medicine
Prem K Raghupathi, Jakob Herschend, Henriette L Røder, Søren J Sørensen, Mette Burmølle
We report the draft genome sequences of twoPseudoclavibacter helvolusstrains. Strain G8 was isolated from a meat chopper and strain W3 isolated from the wall of a small slaughterhouse in Denmark. The two annotated genomes are 3.91 Mb and 4.00 Mb in size, respectively.
2016: Genome Announcements
Prem K Raghupathi, Jakob Herschend, Henriette L Røder, Søren J Sørensen, Mette Burmølle
We report here the first draft genome sequence ofKocuria variansG6, which was isolated from a meat chopper at a small slaughterhouse in Denmark. The 2.90-Mb genome sequence consists of 95 contigs and contains 2,518 predicted protein-coding genes.
2016: Genome Announcements
Jakob Herschend, Prem K Raghupathi, Henriette L Røder, Søren J Sørensen, Mette Burmølle
We report here the draft genome sequences ofKocuria salsiciaG1 andKocuria rhizophilaG2, which were isolated from a meat chopper at a small slaughterhouse in Denmark. The two annotated genomes are 2.99 Mb and 2.88 Mb in size, respectively.
2016: Genome Announcements
Neil J Ingham, Naoya Itatani, Stefan Bleeck, Ian M Winter
A neuron׳s response to a sound can be suppressed by the presentation of a preceding sound. It has been suggested that this suppression is a direct correlate of the psychophysical phenomenon of forward masking, however, forward suppression, as measured in the responses of the auditory nerve, was insufficient to account for behavioural performance. In contrast the neural suppression seen in the inferior colliculus and auditory cortex was much closer to psychophysical performance. In anaesthetised guinea-pigs, using a physiological two-interval forced-choice threshold tracking algorithm to estimate suppressed (masked) thresholds, we examine whether the enhancement of suppression can occur at an earlier stage of the auditory pathway, the ventral cochlear nucleus (VCN)...
May 15, 2016: Brain Research
Takashi Ohhara, Ryoji Kiyanagi, Kenichi Oikawa, Koji Kaneko, Takuro Kawasaki, Itaru Tamura, Akiko Nakao, Takayasu Hanashima, Koji Munakata, Taketo Moyoshi, Tetsuya Kuroda, Hiroyuki Kimura, Terutoshi Sakakura, Chang-Hee Lee, Miwako Takahashi, Ken-Ichi Ohshima, Tamiko Kiyotani, Yukio Noda, Masatoshi Arai
SENJU is a new single-crystal time-of-flight neutron diffractometer installed at BL18 at the Materials and Life Science Experimental Facility of the Japan Accelerator Research Complex (J-PARC). The diffractometer was designed for precise crystal and magnetic structure analyses under multiple extreme sample environments such as low temperature, high pressure and high magnetic field, and for diffraction measurements of small single crystals down to 0.1 mm(3) in volume. SENJU comprises three choppers, an elliptical shape straight supermirror guide, a vacuum sample chamber and 37 scintillator area detectors...
February 1, 2016: Journal of Applied Crystallography
Q Wu, H Y Ma, Y Yang, L T Sun, X Z Zhang, Z M Zhang, H Y Zhao, Y He, H W Zhao
Two compact intense 2.45 GHz permanent magnet proton sources and their corresponding low energy beam transport (LEBT) system were developed successfully for China accelerator driven sub-critical system in 2014. Both the proton sources operate at 35 kV potential. The beams extracted from the ion source are transported by the LEBT, which is composed of two identical solenoids, to the 2.1 MeV Radio-Frequency Quadrupole (RFQ). In order to ensure the safety of the superconducting cavities during commissioning, an electrostatic-chopper has been designed and installed in the LEBT line that can chop the continuous wave beam into a pulsed one...
February 2016: Review of Scientific Instruments
Raphael Gobin, Daniel Bogard, Benoit Bolzon, Gilles Bourdelle, Nicolas Chauvin, Stéphane Chel, Patrick Girardot, Adelino Gomes, Patrice Guiho, Francis Harrault, Denis Loiseau, Yves Lussignol, Nicolas Misiara, Arnaud Roger, Franck Senée, Matthieu Valette, Philippe Cara, Daniel Duglué, Dominique Gex, Yoshikazu Okumura, Juan Marcos Ayala, Juan Knaster, Alvaro Marqueta, Atsushi Kasugai, Shigeru O'Hira, Katsuhiro Shinto, Hiroki Takahashi
The International Fusion Materials Irradiation Facility (IFMIF) linear IFMIF prototype accelerator injector dedicated to high intensity deuteron beam production has been designed, built, and tested at CEA/Saclay between 2008 and 2012. After the completion of the acceptance tests at Saclay, the injector has been fully sent to Japan. The re-assembly of the injector has been performed between March and May 2014. Then after the check-out phase, the production of the first proton beam occurred in November 2014. Hydrogen and deuteron beam commissioning is now in progress after having proceeded with the final tests on the entire injector equipment including high power diagnostics...
February 2016: Review of Scientific Instruments
A Salvador Palau, S D Eder, T Kaltenbacher, B Samelin, G Bracco, B Holst
Time-of-flight (TOF) is a standard experimental technique for determining, among others, the speed ratio S (velocity spread) of a molecular beam. The speed ratio is a measure for the monochromaticity of the beam and an accurate determination of S is crucial for various applications, for example, for characterising chromatic aberrations in focussing experiments related to helium microscopy or for precise measurements of surface phonons and surface structures in molecular beam scattering experiments. For both of these applications, it is desirable to have as high a speed ratio as possible...
February 2016: Review of Scientific Instruments
Xianlin Zheng, Xingjun Zhu, Yiqing Lu, Jiangbo Zhao, Wei Feng, Guohua Jia, Fan Wang, Fuyou Li, Dayong Jin
Optical imaging through the near-infrared (NIR) window provides deep penetration of light up to several centimeters into biological tissues. Capable of emitting 800 nm luminescence under 980 nm illumination, the recently developed upconversion nanoparticles (UCNPs) suggest a promising optical contrast agent for in vivo bioimaging. However, presently they require high-power lasers to excite when applied to small animals, leading to significant scattering background that limits the detection sensitivity as well as a detrimental thermal effect...
April 5, 2016: Analytical Chemistry
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