Internal stray radiation measurement for cryogenic infrared imaging systems using a spherical mirror.

PubMed

Tian, Qijie; Chang, Songtao; He, Fengyun; Li, Zhou; Qiao, Yanfeng

2017-06-10

Internal stray radiation is a key factor that influences infrared imaging systems, and its suppression level is an important criterion to evaluate system performance, especially for cryogenic infrared imaging systems, which are highly sensitive to thermal sources. In order to achieve accurate measurement for internal stray radiation, an approach is proposed, which is based on radiometric calibration using a spherical mirror. First of all, the theory of spherical mirror design is introduced. Then, the calibration formula considering the integration time is presented. Following this, the details regarding the measurement method are presented. By placing a spherical mirror in front of the infrared detector, the influence of internal factors of the detector on system output can be obtained. According to the calibration results of the infrared imaging system, the output caused by internal stray radiation can be acquired. Finally, several experiments are performed in a chamber with controllable inside temperatures to validate the theory proposed in this paper. Experimental results show that the measurement results are in good accordance with the theoretical analysis, and demonstrate that the proposed theories are valid and can be employed in practical applications. The proposed method can achieve accurate measurement for internal stray radiation at arbitrary integration time and ambient temperatures. The measurement result can be used to evaluate whether the suppression level meets the system requirement.

The Disturbing Effect of the Stray Magnetic Fields on Magnetoimpedance Sensors

PubMed Central

Wang, Tao; Zhou, Yong; Lei, Chong; Zhi, Shaotao; Guo, Lei; Li, Hengyu; Wu, Zhizheng; Xie, Shaorong; Luo, Jun; Pu, Huayan

2016-01-01

The disturbing effect of the stray magnetic fields of Fe-based amorphous ribbons on the giant magnetoimpedance (GMI) sensor has been investigated systematically in this paper. Two simple methods were used for examining the disturbing effect of the stray magnetic fields of ribbons on the GMI sensor. In order to study the influence of the stray magnetic fields on the GMI effect, the square-shaped amorphous ribbons were tested in front, at the back, on the left and on the top of a meander-line GMI sensor made up of soft ferromagnetic films, respectively. Experimental results show that the presence of ribbons in front or at the back of GMI sensor shifts the GMI curve to a lower external magnetic field. On the contrary, the presence of ribbons on the left or on the top of the GMI sensor shifts the GMI curve to a higher external magnetic field, which is related to the coupling effect of the external magnetic field and the stray magnetic fields. The influence of the area and angle of ribbons on GMI was also studied in this work. The GMI sensor exhibits high linearity for detection of the stray magnetic fields, which has made it feasible to construct a sensitive magnetometer for detecting the typical stray magnetic fields of general soft ferromagnetic materials. PMID:27763498

Measurement of stray neutron doses inside the treatment room from a proton pencil beam scanning system.

PubMed

Mojżeszek, N; Farah, J; Kłodowska, M; Ploc, O; Stolarczyk, L; Waligórski, M P R; Olko, P

2017-02-01

To measure the environmental doses from stray neutrons in the vicinity of a solid slab phantom as a function of beam energy, field size and modulation width, using the proton pencil beam scanning (PBS) technique. Measurements were carried out using two extended range WENDI-II rem-counters and three tissue equivalent proportional counters. Detectors were suitably placed at different distances around the RW3 slab phantom. Beam irradiation parameters were varied to cover the clinical ranges of proton beam energies (100-220MeV), field sizes ((2×2)-(20×20)cm 2 ) and modulation widths (0-15cm). For pristine proton peak irradiations, large variations of neutron H ∗ (10)/D were observed with changes in beam energy and field size, while these were less dependent on modulation widths. H ∗ (10)/D for pristine proton pencil beams varied between 0.04μSvGy -1 at beam energy 100MeV and a (2×2)cm 2 field at 2.25m distance and 90° angle with respect to the beam axis, and 72.3μSvGy -1 at beam energy 200MeV and a (20×20) cm 2 field at 1m distance along the beam axis. The obtained results will be useful in benchmarking Monte Carlo calculations of proton radiotherapy in PBS mode and in estimating the exposure to stray radiation of the patient. Such estimates may be facilitated by the obtained best-fitted simple analytical formulae relating the stray neutron doses at points of interest with beam irradiation parameters. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A general model for stray dose calculation of static and intensity-modulated photon radiation.

PubMed

Hauri, Pascal; Hälg, Roger A; Besserer, Jürgen; Schneider, Uwe

2016-04-01

There is an increasing number of cancer survivors who are at risk of developing late effects caused by ionizing radiation such as induction of second tumors. Hence, the determination of out-of-field dose for a particular treatment plan in the patient's anatomy is of great importance. The purpose of this study was to analytically model the stray dose according to its three major components. For patient scatter, a mechanistic model was developed. For collimator scatter and head leakage, an empirical approach was used. The models utilize a nominal beam energy of 6 MeV to describe two linear accelerator types of a single vendor. The parameters of the models were adjusted using ionization chamber measurements registering total absorbed dose in simple geometries. Whole-body dose measurements using thermoluminescent dosimeters in an anthropomorphic phantom for static and intensity-modulated treatment plans were compared to the 3D out-of-field dose distributions calculated by a combined model. The absolute mean difference between the whole-body predicted and the measured out-of-field dose of four different plans was 11% with a maximum difference below 44%. Computation time of 36 000 dose points for one field was around 30 s. By combining the model-calculated stray dose with the treatment planning system dose, the whole-body dose distribution can be viewed in the treatment planning system. The results suggest that the model is accurate, fast and can be used for a wide range of treatment modalities to calculate the whole-body dose distribution for clinical analysis. For similar energy spectra, the mechanistic patient scatter model can be used independently of treatment machine or beam orientation.

Development of the CSNS Lambertson magnet with very low stray field

NASA Astrophysics Data System (ADS)

Wu, Yuwen; Kang, Wen; Chen, Yuan; Wu, Xi; Li, Shuai; Wang, Lei; Deng, Changdong; Li, Li; Zhou, Jianxin; Liu, Yiqin

2018-02-01

In this paper, the magnetic and mechanical design of Lambertson are studied, and then magnetic field measurements are introduced. The results show that the integral field uniformity and effective length meet the physical requirements. The shielding measures shield the stray field effectively and the stray field along the circulating beam orbit is at a very low level.

Performance of mobile digital X-ray fluoroscopy using a novel flat panel detector for intraoperative use.

PubMed

Jeong, Chang-Won; Ryu, Jong-Hyun; Joo, Su-Chong; Jun, Hong-Young; Heo, Dong-Woon; Lee, Jinseok; Kim, Kyong-Woo; Yoon, Kwon-Ha

2015-01-01

Technologies employing digital X-ray devices are developed for mobile settings. To develop a mobile digital X-ray fluoroscopy (MDF) for intraoperative guidance, using a novel flat panel detector to focus on diagnostics in outpatient clinics, operating and emergency rooms. An MDF for small-scale field diagnostics was configured using an X-ray source and a novel flat panel detector. The imager enabled frame rates reaching 30 fps in full resolution fluoroscopy with maximal running time of 5 minutes. Signal-to-noise (SNR), contrast-to-noise (CNR), and spatial resolution were analyzed. Stray radiation, exposure radiation dose, and effective absorption dose were measured for patients. The system was suitable for small-scale field diagnostics. SNR and CNR were 62.4 and 72.0. Performance at 10% of MTF was 9.6 lp/mm (53 μ m) in the no binned mode. Stray radiation at 100 cm and 150 cm from the source was below 0.2 μ Gy and 0.1 μ Gy. Exposure radiation in radiography and fluoroscopy (5 min) was 10.2 μ Gy and 82.6 mGy. The effective doses during 5-min-long fluoroscopy were 0.26 mSv (wrist), 0.28 mSv (elbow), 0.29 mSv (ankle), and 0.31 mSv (knee). The proposed MDF is suitable for imaging in operating rooms.

Comparison of risk of radiogenic second cancer following photon and proton craniospinal irradiation for a pediatric medulloblastoma patient

NASA Astrophysics Data System (ADS)

Zhang, Rui; Howell, Rebecca M.; Giebeler, Annelise; Taddei, Phillip J.; Mahajan, Anita; Newhauser, Wayne D.

2013-02-01

Pediatric patients who received radiation therapy are at risk of developing side effects such as radiogenic second cancer. We compared proton and photon therapies in terms of the predicted risk of second cancers for a 4 year old medulloblastoma patient receiving craniospinal irradiation (CSI). Two CSI treatment plans with 23.4 Gy or Gy (RBE) prescribed dose were computed: a three-field 6 MV photon therapy plan and a four-field proton therapy plan. The primary doses for both plans were determined using a commercial treatment planning system. Stray radiation doses for proton therapy were determined from Monte Carlo simulations, and stray radiation doses for photon therapy were determined from measured data. Dose-risk models based on the Biological Effects of Ionization Radiation VII report were used to estimate the risk of second cancer in eight tissues/organs. Baseline predictions of the relative risk for each organ were always less for proton CSI than for photon CSI at all attained ages. The total lifetime attributable risk of the incidence of second cancer considered after proton CSI was much lower than that after photon CSI, and the ratio of lifetime risk was 0.18. Uncertainty analysis revealed that the qualitative findings of this study were insensitive to any plausible changes of dose-risk models and mean radiation weighting factor for neutrons. Proton therapy confers lower predicted risk of second cancer than photon therapy for the pediatric medulloblastoma patient.

Enhancement of switching stability of tunneling magnetoresistance system with artificial ferrimagnet

NASA Astrophysics Data System (ADS)

You, Chun-Yeol; Bader, Sam. D.; Scheinfein, M. R.

2002-03-01

In the study of spin dependent magnetic tunneling junctions, the switching stability of the magnetically hard layer is a crucial issue in magnetic random access memory applications[1]. After repeated cycling of the soft layer, the magnetization of the hard layer is demagnetized by the stray field from the domain wall created during the switching[2]. The magnitude of the stray field from the soft layer is large enough to switch a domain in the hard layer. Therefore, reducing this stray field is necessary to increase the switching stability. In this study, we explore an artificial ferrimagnet to replace the usual soft layer in order to reduce stray field. The ferrimagnet consists of an antiferromagnetically coupled trilayer that has two ferromagnetic layers of unequal thickness and opposite magnetization orientation. Since the sign of stray field of the two ferromagnetic layers is opposed, the total stray field is greatly reduced. [Supported by the US DOE, BES-MS, under Contract W-31-109-ENG-38.] [1] S. Gider et al. Science 281, 797 (1998). [2] L. Thomas et al. Phys. Rev. Lett. 84, 1816 (2000).

Stray light in cone beam optical computed tomography: I. Measurement and reduction strategies with planar diffuse source

NASA Astrophysics Data System (ADS)

Granton, Patrick V.; Dekker, Kurtis H.; Battista, Jerry J.; Jordan, Kevin J.

2016-04-01

Optical cone-beam computed tomographic (CBCT) scanning of 3D radiochromic dosimeters may provide a practical method for 3D dose verification in radiation therapy. However, in cone-beam geometry stray light contaminates the projection images, degrading the accuracy of reconstructed linear attenuation coefficients. Stray light was measured using a beam pass aperture array (BPA) and structured illumination methods. The stray-to-primary ray ratio (SPR) along the central axis was found to be 0.24 for a 5% gelatin hydrogel, representative of radiochromic hydrogels. The scanner was modified by moving the spectral filter from the detector to the source, changing the light’s spatial fluence pattern and lowering the acceptance angle by extending distance between the source and object. These modifications reduced the SPR significantly from 0.24 to 0.06. The accuracy of the reconstructed linear attenuation coefficients for uniform carbon black liquids was compared to independent spectrometer measurements. Reducing the stray light increased the range of accurate transmission readings. In order to evaluate scanner performance for the more challenging application to small field dosimetry, a carbon black finger gel phantom was prepared. Reconstructions of the phantom from CBCT and fan-beam CT scans were compared. The modified source resulted in improved agreement. Subtraction of residual stray light, measured with BPA or structured illumination from each projection further improved agreement. Structured illumination was superior to BPA for measuring stray light for the smaller 1.2 and 0.5 cm diameter phantom fingers. At the costs of doubling the scanner size and tripling the number of scans, CBCT reconstructions of low-scattering hydrogel dosimeters agreed with those of fan-beam CT scans.

Monitoring millimeter wave stray radiation during ECRH operation at ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Schubert, M.; Honecker, F.; Monaco, F.; Schmid-Lorch, D.; Schütz, H.; Stober, J.; Wagner, D.

2012-09-01

Due to imperfection of the single path absorption, ECRH at ASDEX Upgrade (AUG) is always accompanied by stray radiation in the vacuum vessel. New ECRH scenarios with O2 and X3 heating schemes extend the operational space, but they have also the potential to increase the level of stray radiation. There are hazards for invessel components. Damage on electric cables has already been encountered. It is therefore necessary to monitor and control the ECRH with respect to the stray radiation level. At AUG a system of Sniffer antennas equipped with microwave detection diodes is installed. The system is part of the ECRH interlock circuit. We notice, however, that during plasma operation the variations of the Sniffer antenna signal are very large. In laboratory measurements we see variations of up to 20 dB in the directional sensitivity and we conclude that an interference pattern is formed inside the copper sphere of the antenna. When ECRH is in plasma operation at AUG, the plasma is acting as a phase and mode mixer for the millimeter waves and thus the interference pattern inside the sphere changes with the characteristic time of the plasma dynamics. In order to overcome the difficulty of a calibrated measurement of the average stray radiation level, we installed bolometer and pyroelectric detectors, which intrinsically average over interference structures due to their large active area. The bolometer provides a robust calibration but with moderate temporal resolution. The pyroelectric detector provides high sensitivity and a good temporal resolution, but it raises issues of possible signal drifts in long pulses.

The influence of the earth radiation on space target detection system

NASA Astrophysics Data System (ADS)

Su, Xiaofeng; Chen, FanSheng; Cuikun, .; Liuyan, .

2017-05-01

In the view of space remote sensing such as satellite detection space debris detection etc. visible band is usually used in order to have the all-weather detection capability, long wavelength infrared (LWIR) detection is also an important supplement. However, in the tow wave band, the earth can be a very strong interference source, especially in the dim target detecting. When the target is close to the earth, especially the LEO target, the background radiation of the earth will also enter into the baffle, and became the stray light through reflection, the stray light can reduce the signal to clutter ratio (SCR) of the target and make it difficult to be detected. In the visible band, the solar albedo by the earth is the main clutter source while in the LWIR band the radiation of the earth is the main clutter source. So, in this paper, we establish the energy transformation from the earth background radiation to the detection system to assess the effects of the stray light. Firstly, we discretize the surface of the earth to different unit, and using MODTRAN to calculate the radiation of the discrete point in different light and climate conditions, then, we integral all the radiation which can reach the baffle in the same observation angles to get the energy distribution, finally, according the target energy and the non-uniformity of the detector, we can calculate the design requirement of the system stray light suppression, which provides the design basis for the optical system.

Convergence of highly parallel stray field calculation using the fast multipole method on irregular meshes

NASA Astrophysics Data System (ADS)

Palmesi, P.; Abert, C.; Bruckner, F.; Suess, D.

2018-05-01

Fast stray field calculation is commonly considered of great importance for micromagnetic simulations, since it is the most time consuming part of the simulation. The Fast Multipole Method (FMM) has displayed linear O(N) parallelization behavior on many cores. This article investigates the error of a recent FMM approach approximating sources using linear—instead of constant—finite elements in the singular integral for calculating the stray field and the corresponding potential. After measuring performance in an earlier manuscript, this manuscript investigates the convergence of the relative L2 error for several FMM simulation parameters. Various scenarios either calculating the stray field directly or via potential are discussed.

Stray light correction on array spectroradiometers for optical radiation risk assessment in the workplace.

PubMed

Barlier-Salsi, A

2014-12-01

The European directive 2006/25/EC requires the employer to assess and, if necessary, measure the levels of exposure to optical radiation in the workplace. Array spectroradiometers can measure optical radiation from various types of sources; however poor stray light rejection affects their accuracy. A stray light correction matrix, using a tunable laser, was developed at the National Institute of Standards and Technology (NIST). As tunable lasers are very expensive, the purpose of this study was to implement this method using only nine low power lasers; other elements of the correction matrix being completed by interpolation and extrapolation. The correction efficiency was evaluated by comparing CCD spectroradiometers with and without correction and a scanning double monochromator device as reference. Similar to findings recorded by NIST, these experiments show that it is possible to reduce the spectral stray light by one or two orders of magnitude. In terms of workplace risk assessment, this spectral stray light correction method helps determine exposure levels, with an acceptable degree of uncertainty, for the majority of workplace situations. The level of uncertainty depends upon the model of spectroradiometers used; the best results are obtained with CCD detectors having an enhanced spectral sensitivity in the UV range. Thus corrected spectroradiometers require a validation against a scanning double monochromator spectroradiometer before using them for risk assessment in the workplace.

Interaction between Stray Electrostatic Fields and a Charged Free-Falling Test Mass

NASA Astrophysics Data System (ADS)

Antonucci, F.; Cavalleri, A.; Dolesi, R.; Hueller, M.; Nicolodi, D.; Tu, H. B.; Vitale, S.; Weber, W. J.

2012-05-01

We present an experimental analysis of force noise caused by stray electrostatic fields acting on a charged test mass inside a conducting enclosure, a key problem for precise gravitational experiments. Measurement of the average field that couples to the test mass charge, and its fluctuations, is performed with two independent torsion pendulum techniques, including direct measurement of the forces caused by a change in electrostatic charge. We analyze the problem with an improved electrostatic model that, coupled with the experimental data, also indicates how to correctly measure and null the stray field that interacts with the test mass charge. Our measurements allow a conservative upper limit on acceleration noise, of 2(fm/s2)/Hz1/2 for frequencies above 0.1 mHz, for the interaction between stray fields and charge in the LISA gravitational wave mission.

Magnetic properties of artificially designed magnetic stray field landscapes in laterally confined exchange-bias layers.

PubMed

Mitin, D; Kovacs, A; Schrefl, T; Ehresmann, A; Holzinger, D; Albrecht, M

2018-08-31

Magnetic stray fields generated by domain walls (DWs) have attracted significant attention as they might be employed for precise positioning and active control of micro- and nano-sized magnetic objects in fluids or in the field of magnonics. The presented work intends to investigate the near-field response of magnetic stray field landscapes above generic types of charged DWs as occurring in thin films with in-plane anisotropy and preferential formation of Néel type DWs when disturbed by external magnetic fields. For this purpose, artificial magnetic stripe domain patterns with three defined domain configurations, i.e. head-to-head (tail-to-tail), head-to-side, and side-by-side, were fabricated via ion bombardment induced magnetic patterning of an exchange-biased IrMn/CoFe bilayer. The magnetic stray field landscapes as well as the local magnetization reversal of the various domain configurations were analyzed in an external magnetic field by scanning magnetoresistive microscopy and compared to micromagnetic simulations.

Interaction between stray electrostatic fields and a charged free-falling test mass.

PubMed

Antonucci, F; Cavalleri, A; Dolesi, R; Hueller, M; Nicolodi, D; Tu, H B; Vitale, S; Weber, W J

2012-05-04

We present an experimental analysis of force noise caused by stray electrostatic fields acting on a charged test mass inside a conducting enclosure, a key problem for precise gravitational experiments. Measurement of the average field that couples to the test mass charge, and its fluctuations, is performed with two independent torsion pendulum techniques, including direct measurement of the forces caused by a change in electrostatic charge. We analyze the problem with an improved electrostatic model that, coupled with the experimental data, also indicates how to correctly measure and null the stray field that interacts with the test mass charge. Our measurements allow a conservative upper limit on acceleration noise, of 2  (fm/s2)/Hz(1/2) for frequencies above 0.1 mHz, for the interaction between stray fields and charge in the LISA gravitational wave mission.

Use of Cold Radiometers in Several Thermal/Vacuum Tests

NASA Technical Reports Server (NTRS)

DiPirro, M.; Tuttle, J.; Canavan, E.; Shirron, P.

2011-01-01

We have developed a low cost low temperature broadband radiometer for use with low temperature tests as a diagnostic tool for measuring stray thermal radiation and remote measurement of material properties. So far these radiometers have been used in two large thermal/vacuum tests for the James Webb Space Telescope (JWST) Project. In the first test the radiometers measured stray radiation in a test of part of the JWST sunshield, and in the second test the radiometers were used to measure the reflectivity and specularity of black Z307 painted aluminum walls on a 25 K cooled shroud. These results will be presented as well as plans for future tests to measure the residual energy through a baffled aperture in the shroud and other stray thermal energy measurements.

Extremely low frequency (ELF) stray magnetic fields of laboratory equipment: a possible co-exposure conducting experiments on cell cultures.

PubMed

Gresits, Iván; Necz, Péter Pál; Jánossy, Gábor; Thuróczy, György

2015-09-01

Measurements of extremely low frequency (ELF) magnetic fields were conducted in the environment of commercial laboratory equipment in order to evaluate the possible co-exposure during the experimental processes on cell cultures. Three types of device were evaluated: a cell culture CO2 incubator, a thermostatic water bath and a laboratory shaker table. These devices usually have electric motors, heating wires and electronic control systems, therefore may expose the cell cultures to undesirable ELF stray magnetic fields. Spatial distributions of magnetic field time domain signal waveform and frequency spectral analysis (FFT) were processed. Long- and short-term variation of stray magnetic field was also evaluated under normal use of investigated laboratory devices. The results show that the equipment under test may add a considerable ELF magnetic field to the ambient environmental magnetic field or to the intentional exposure to ELF, RF or other physical/chemical agents. The maximum stray magnetic fields were higher than 3 µT, 20 µT and 75 µT in the CO2 incubator, in water bath and on the laboratory shaker table, respectively, with high variation of spatial distribution and time domain. Our investigation emphasizes possible confounding factors conducting cell culture studies related to low-level ELF-EMF exposure due to the existing stray magnetic fields in the ambient environment of laboratory equipment.

Numerical simulations on active shielding methods comparison and wrapped angle optimization for gradient coil design in MRI with enhanced shielding effect

NASA Astrophysics Data System (ADS)

Wang, Yaohui; Xin, Xuegang; Guo, Lei; Chen, Zhifeng; Liu, Feng

2018-05-01

The switching of a gradient coil current in magnetic resonance imaging will induce an eddy current in the surrounding conducting structures while the secondary magnetic field produced by the eddy current is harmful for the imaging. To minimize the eddy current effects, the stray field shielding in the gradient coil design is usually realized by minimizing the magnetic fields on the cryostat surface or the secondary magnetic fields over the imaging region. In this work, we explicitly compared these two active shielding design methods. Both the stray field and eddy current on the cryostat inner surface were quantitatively discussed by setting the stray field constraint with an ultra-low maximum intensity of 2 G and setting the secondary field constraint with an extreme small shielding ratio of 0.000 001. The investigation revealed that the secondary magnetic field control strategy can produce coils with a better performance. However, the former (minimizing the magnetic fields) is preferable when designing a gradient coil with an ultra-low eddy current that can also strictly control the stray field leakage at the edge of the cryostat inner surface. A wrapped-edge gradient coil design scheme was then optimized for a more effective control of the stray fields. The numerical simulation on the wrapped-edge coil design shows that the optimized wrapping angles for the x and z coils in terms of our coil dimensions are 40° and 90°, respectively.

Collective backscattering of gyrotron radiation by small-scale plasma density fluctuations in large helical device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kharchev, Nikolay; Batanov, German; Petrov, Alexandr

2008-10-15

A version of the collective backscattering diagnostic using gyrotron radiation for small-scale turbulence is described. The diagnostic is used to measure small-scale (k{sub s}{approx_equal}34 cm{sup -1}) plasma density fluctuations in large helical device experiments on the electron cyclotron heating of plasma with the use of 200 kW 82.7 GHz heating gyrotron. A good signal to noise ratio during plasma production phase was obtained, while contamination of stray light increased during plasma build-up phase. The effect of the stray radiation was investigated. The available quasioptical system of the heating system was utilized for this purpose.

Experimental Determination of Ultra-Sharp Stray Field Distribution from a Magnetic Vortex Core Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, L.; Zhu, Y.; Zhong, H.

2009-08-01

The fine magnetic stray field from a vortex structure of micron-sized permalloy (Ni{sub 80}Fe{sub 20}) elements has been studied by high-resolution magnetic force microscopy. By systematically studying the width of the stray field gradient distribution at different tip-to-sample distances, we show that the half-width at half-maximum (HWHM) of the signal from vortex core can be as narrow as {approx}21 nm at a closest tip-to-sample distance of 23 nm, even including the convolution effect of the finite size of the magnetic tip. A weak circular reverse component is found around the center of the magnetic vortex in the measured magnetic forcemore » microscope (MFM) signals, which can be attributed to the reverse magnetization around the vortex core. Successive micromagnetic and MFM imaging simulations show good agreements with our experimental results on the width of the stray field distribution.« less

Effects of media stray field on electromigration characteristics in current-perpendicular-to-plane giant magnetoresistance spin-valve read sensors

NASA Astrophysics Data System (ADS)

Gui Zeng, Ding; Lee, Kyoung-il; Chung, Kyung-Won; Bae, Seongtae

2012-05-01

Effects of magnetic stray field retrieved from both longitudinal and perpendicular magnetic recording media (denoted by "media stray field") on electromigration (EM) characteristics of current-perpendicular-to-plane (CPP) giant magnetoresistance spin-valve (GMR SV) read sensors have been numerically studied to explore the electrical and magnetic stability of the read sensor under real operation. The mean-time-to-failure (MTTF) of the CPP GMR SV read sensors was found to have a strong dependence on the physical parameters of the recording media and recorded information status, such as the pulse width of media stray field, the bit length, and the head moving velocity. According to the numerical calculation results, it was confirmed that in the longitudinal media, the shorter the stray field pulse width (i.e., the sharper the media transition) allows for the longer MTTF of the CPP GMR SV read sensors; while in the perpendicular media, the sharper the media transition gives rise to a shorter MTTF. Interestingly, it was also revealed that the MTTF could be improved by reducing the bit length as well as increasing the head velocity in both longitudinal and perpendicular media. Furthermore, the bit distribution patterns, especially the number of consecutive `0' bits strongly affected the MTTF of GMR SV read sensors. The strong dependences of MTTF on the media stray field during CPP GMR SV sensor operation are thought to be mainly attributed to the thermal cycling (temperature rise and fall) caused by the resistance change due to GMR effects.

Solar rejection for an orbiting telescope

NASA Technical Reports Server (NTRS)

Rehnberg, J. D.

1975-01-01

The present work discusses some of the constraints that the optical designer must deal with in optimizing spaceborne sensors that must look at or near the sun. Analytical techniques are described for predicting the effects of stray radiation from sources such as mirror scatter, baffle scatter, diffraction, and ghost images. In addition, the paper describes a sensor design that has been flown on the Apollo Telescope Mount (Skylab) to aid astronauts in locating solar flares. In addition to keeping stray radiation to a minimum, the design had to be nondegradable by the direct solar heat load.

Common but unappreciated sources of error in one, two, and multiple-color pyrometry

NASA Technical Reports Server (NTRS)

Spjut, R. Erik

1988-01-01

The most common sources of error in optical pyrometry are examined. They can be classified as either noise and uncertainty errors, stray radiation errors, or speed-of-response errors. Through judicious choice of detectors and optical wavelengths the effect of noise errors can be minimized, but one should strive to determine as many of the system properties as possible. Careful consideration of the optical-collection system can minimize stray radiation errors. Careful consideration must also be given to the slowest elements in a pyrometer when measuring rapid phenomena.

Co thickness dependence of structural and magnetic properties in spin quantum cross devices utilizing stray magnetic fields

NASA Astrophysics Data System (ADS)

Kaiju, H.; Kasa, H.; Komine, T.; Mori, S.; Misawa, T.; Abe, T.; Nishii, J.

2015-05-01

We investigate the Co thickness dependence of the structural and magnetic properties of Co thin-film electrodes sandwiched between borate glasses in spin quantum cross (SQC) devices that utilize stray magnetic fields. We also calculate the Co thickness dependence of the stray field between the two edges of Co thin-film electrodes in SQC devices using micromagnetic simulation. The surface roughness of Co thin films with a thickness of less than 20 nm on borate glasses is shown to be as small as 0.18 nm, at the same scanning scale as the Co film thickness, and the squareness of the hysteresis loop is shown to be as large as 0.96-1.0. As a result of the establishment of polishing techniques for Co thin-film electrodes sandwiched between borate glasses, we successfully demonstrate the formation of smooth Co edges and the generation of stray magnetic fields from Co edges. Theoretical calculation reveals that a strong stray field beyond 6 kOe is generated when the Co thickness is greater than 10 nm at a junction gap distance of 5 nm. From these experimental and calculation results, it can be concluded that SQC devices with a Co thickness of 10-20 nm can be expected to function as spin-filter devices.

Whole-body dose and energy measurements in radiotherapy by a combination of LiF:Mg,Cu,P and LiF:Mg,Ti.

PubMed

Hauri, Pascal; Schneider, Uwe

2018-04-01

Long-term survivors of cancer who were treated with radiotherapy are at risk of a radiation-induced tumor. Hence, it is important to model the out-of-field dose resulting from a cancer treatment. These models have to be verified with measurements, due to the small size, the high sensitivity to ionizing radiation and the tissue-equivalent composition, LiF thermoluminescence dosimeters (TLD) are well-suited for out-of-field dose measurements. However, the photon energy variation of the stray dose leads to systematic dose errors caused by the variation in response with radiation energy of the TLDs. We present a dosimeter which automatically corrects for the energy variation of the measured photons by combining LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P (TLD100H) chips. The response with radiation energy of TLD100 and TLD100H compared to 60 Co was taken from the literature. For the measurement, a TLD100H was placed on top of a TLD100 chip. The dose ratio between the TLD100 and TLD100H, combined with the ratio of the response curves was used to determine the mean energy. With the energy, the individual correction factors for TLD100 and TLD100H could be found. The accuracy in determining the in- and out-of-field dose for a nominal beam energy of 6MV using the double-TLD unit was evaluated by an end-to-end measurement. Furthermore, published Monte Carlo (M.C.) simulations of the mean photon energy for brachytherapy sources, stray radiation of a treatment machine and cone beam CT (CBCT) were compared to the measured mean energies. Finally, the photon energy distribution in an Alderson phantom was measured for different treatment techniques applied with a linear accelerator. Additionally, a treatment plan was measured with a cobalt machine combined with an MRI. For external radiotherapy, the presented double-TLD unit showed a relative type A uncertainty in doses of -1%±2% at the two standard deviation level compared to an ionization chamber. The type A uncertainty in dose was in agreement with the theoretically calculated type B uncertainty. The measured energies for brachytherapy sources, stray radiation of a treatment machine and CBCT imaging were in agreement with M.C. simulations. A shift in energy with increasing distance to the isocenter was noticed for the various treatment plans measured with the Alderson phantom. The calculated type B uncertainties in energy were in line with the experimentally evaluated type A uncertainties. The double-TLD unit is able to predict the photon energy of scatter radiation in external radiotherapy, X-ray imagine and brachytherapy sources. For external radiotherapy, the individual energy correction factors enabled a more accurate dose determination compared to conventional TLD measurements. Copyright © 2017. Published by Elsevier GmbH.

Stray light suppression of optical and mechanical system for telescope detection

NASA Astrophysics Data System (ADS)

Wang, Lei; Ma, Wenli

2013-09-01

During telescope detection, there is atmosphere overflow and other stray light affecting the system which leads to background disturbance. Thus reduce the detection capability of the system. So it is very necessary to design mechanical structure to suppress the stray light for the telescope detection system. It can both improve the signal-to-noise and contrast of the object. This paper designs the optical and mechanical structure of the 400mm telescope. And then the main baffle, baffle vane, field stop and coating technology are used to eliminate the effect of stray light on the optical and mechanical system. Finally, software is used to analyze and simulate stray light on the whole optical and mechanical system. Using PST as the evaluating standard, separate and integrated analysis of the suppressing effect of main baffle, baffle vane and field aperture is completed. And also get the results of PST before and after eliminating the stray light. Meanwhile, the results of stray light analysis can be used to guide the design of the optical and mechanical structure. The analysis results demonstrate that reasonable optical and mechanical structure and stray light suppression measure can highly reduce the PST and also improve the detection capability of the telescope system, and the designed outside baffle, inside baffle, vanes and coating technique etc. can decrease the PST approximately 1 to 3 level.

Controlling stray electric fields on an atom chip for experiments on Rydberg atoms

NASA Astrophysics Data System (ADS)

Davtyan, D.; Machluf, S.; Soudijn, M. L.; Naber, J. B.; van Druten, N. J.; van Linden van den Heuvell, H. B.; Spreeuw, R. J. C.

2018-02-01

Experiments handling Rydberg atoms near surfaces must necessarily deal with the high sensitivity of Rydberg atoms to (stray) electric fields that typically emanate from adsorbates on the surface. We demonstrate a method to modify and reduce the stray electric field by changing the adsorbate distribution. We use one of the Rydberg excitation lasers to locally affect the adsorbed dipole distribution. By adjusting the averaged exposure time we change the strength (with the minimal value less than 0.2 V /cm at 78 μ m from the chip) and even the sign of the perpendicular field component. This technique is a useful tool for experiments handling Rydberg atoms near surfaces, including atom chips.

Measurement of stray EC radiation on W7-AS

NASA Astrophysics Data System (ADS)

Gandini, F.; Hirsch, M.; Cirant, S.; Erckmann, V.; Granucci, G.; Kasparek, W.; Laqua, H. P.; Muzzini, V.; Nowak, S.; Radau, S.

2001-10-01

In the framework of a collaboration between IFP-CNR Milano, IPP Garching/Greifswald and IPF Stuttgart, a set of four millimeterwave probes has been installed in W7-AS stellarator at selected positions of the inner vessel wall. Their purpose is to observe RF stray radiation during operation in presence of strong level of Electron Cyclotron (EC) waves, used for plasma start-up, heating and current drive. The aim of these measurements is to benchmark two complementary theoretical models for the distribution of the stray radiation in the vessel. From these codes, quantitative predictions are expected for the spatial distribution of the RF wall load and the RF-impact on in-vessel components in large future devices such as W7-X and, possibly, ITER. This input is important to optimize the wall armour and select rf-compatible in-vessel materials. We present first measurements from different heating and startup scenarios, with up to 800 kW of injected power at 140 GHz and different launching geometries. An analysis of measurements performed on FTU using a previous version of sniffer probe is also presented.

Handheld Reflective Foil Emissometer with 0.007 Absolute Accuracy at 0.05

NASA Astrophysics Data System (ADS)

van der Ham, E. W. M.; Ballico, M. J.

2014-07-01

The development and performance of a handheld emissometer for the measurement of the emissivity of highly reflective metallic foils used for the insulation of domestic and commercial buildings are described. Reflective roofing insulation based on a thin coating of metal on a more robust substrate is very widely used in hotter climates to reduce the radiant heat transfer between the ceiling and roof in commercial and residential buildings. The required normal emissivity of these foils is generally below 0.05, so stray reflected ambient infrared radiation (IR) makes traditional reflectance-based measurements of emissivity very difficult to achieve with the required accuracy. Many manufacturers apply additional coatings onto the metallic foil to reduce visible glare during installation on a roof, and to provide protection to the thin reflective layer; however, this layer can also substantially increase the IR emissivity. The system as developed at the National Measurement Institute, Australia (NMIA) is based on the principle of measurement of the modulation in thermal infrared radiation, as the sample is thermally modulated by hot and cold air streams. A commercial infrared to band radiation thermometer with a highly specialized stray and reflected radiation shroud attachment is used as the detector system, allowing for convenient handheld field measurements. The performance and accuracy of the system have been compared with NMIA's reference emissometer systems for a number of typical material samples, demonstrating its capability to measure the absolute thermal emissivity of these very highly reflective foils with an uncertainty of better than.

Stray light field dependence for large astronomical space telescopes

NASA Astrophysics Data System (ADS)

Lightsey, Paul A.; Bowers, Charles W.

2017-09-01

Future large astronomical telescopes in space will have architectures that expose the optics to large angular extents of the sky. Options for reducing stray light coming from the sky range from enclosing the telescope in a tubular baffle to having an open telescope structure with a large sunshield to eliminate solar illumination. These two options are considered for an on-axis telescope design to explore stray light considerations. A tubular baffle design will limit the sky exposure to the solid angle of the cone in front of the telescope set by the aspect ratio of the baffle length to Primary Mirror (PM) diameter. Illumination from this portion of the sky will be limited to the PM and structures internal to the tubular baffle. Alternatively, an open structure design will allow a large portion of the sky to directly illuminate the PM and Secondary Mirror (SM) as well as illuminating sunshield and other structure surfaces which will reflect or scatter light onto the PM and SM. Portions of this illumination of the PM and SM will be scattered into the optical train as stray light. A Radiance Transfer Function (RTF) is calculated for the open architecture that determines the ratio of the stray light background radiance in the image contributed by a patch of sky having unit radiance. The full 4π steradian of sky is divided into a grid of patches, with the location of each patch defined in the telescope coordinate system. By rotating the celestial sky radiance maps into the telescope coordinate frame for a given pointing direction of the telescope, the RTF may be applied to the sky brightness and the results integrated to get the total stray light from the sky for that pointing direction. The RTF data generated for the open architecture may analyzed as a function of the expanding cone angle about the pointing direction. In this manner, the open architecture data may be used to directly compare to a tubular baffle design parameterized by allowed cone angle based on the aspect ratio of the tubular baffle length to PM diameter. Additional analysis has been done to examine the stray light implications for the fields near the image of a bright source. This near field stray light is shown to be dependent on the Bidirectional Reflectance Distribution Function (BRDF) characteristics of the mirrors in the optical train. The near field stray light contribution is dominated by those mirrors closer to the focal plane compared to the contributions from the PM and SM. Hence the near field stray light is independent of the exterior telescope baffle geometry. Contributions from self-emission from the telescope have been compared to natural background for telescopes operating at infrared wavelengths.

Benchmark studies of induced radioactivity produced in LHC materials, Part I: Specific activities.

PubMed

Brugger, M; Khater, H; Mayer, S; Prinz, A; Roesler, S; Ulrici, L; Vincke, H

2005-01-01

Samples of materials which will be used in the LHC machine for shielding and construction components were irradiated in the stray radiation field of the CERN-EU high-energy reference field facility. After irradiation, the specific activities induced in the various samples were analysed with a high-precision gamma spectrometer at various cooling times, allowing identification of isotopes with a wide range of half-lives. Furthermore, the irradiation experiment was simulated in detail with the FLUKA Monte Carlo code. A comparison of measured and calculated specific activities shows good agreement, supporting the use of FLUKA for estimating the level of induced activity in the LHC.

Nanometer-Scale Force Detected Nuclear Magnetic Resonance Imaging

DTIC Science & Technology

2013-01-01

different crystallographic orientation. Single crystal thin films should thus minimize the stray electric fields by reducing the number of grain ...from epitaxial Ag films, rather than polycrystalline Ag films. It is thought that grain boundaries in polycrystalline metal films give rise to stray...electric fields near the surface of the film. The electric fields are produced as a consequence of the work func- tion difference between grains of

Analysis of stray radiation for infrared optical system

NASA Astrophysics Data System (ADS)

Li, Yang; Zhang, Tingcheng; Liao, Zhibo; Mu, Shengbo; Du, Jianxiang; Wang, Xiangdong

2016-10-01

Based on the theory of radiation energy transfer in the infrared optical system, two methods for stray radiation analysis caused by interior thermal radiation in infrared optical system are proposed, one of which is important sampling method technique using forward ray trace, another of which is integral computation method using reverse ray trace. The two methods are discussed in detail. A concrete infrared optical system is provided. Light-tools is used to simulate the passage of radiation from the mirrors and mounts. Absolute values of internal irradiance on the detector are received. The results shows that the main part of the energy on the detector is due to the critical objects which were consistent with critical objects obtained by reverse ray trace, where mirror self-emission contribution is about 87.5% of the total energy. Corresponding to the results, the irradiance on the detector calculated by the two methods are in good agreement. So the validity and rationality of the two methods are proved.

Application of Peterson's stray light model to complex optical instruments

NASA Astrophysics Data System (ADS)

Fray, S.; Goepel, M.; Kroneberger, M.

2016-07-01

Gary L. Peterson (Breault Research Organization) presented a simple analytical model for in- field stray light evaluation of axial optical systems. We exploited this idea for more complex optical instruments of the Meteosat Third Generation (MTG) mission. For the Flexible Combined Imager (FCI) we evaluated the in-field stray light of its three-mirroranastigmat telescope, while for the Infrared Sounder (IRS) we performed an end-to-end analysis including the front telescope, interferometer and back telescope assembly and the cold optics. A comparison to simulations will be presented. The authors acknowledge the support by ESA and Thales Alenia Space through the MTG satellites program.

Effect of stray electric fields on cooling of center of mass motion of levitated graphite flakes

NASA Astrophysics Data System (ADS)

Nagornykh, Pavel; Coppock, Joyce; Kane, Bruce

2015-03-01

Levitation of charged multilayer graphene flakes in a quadrupole ion trap provides a unique way to study graphene in isolated conditions. Cooling of a flake in such a setup is necessary for high vacuum measurements of the flake and is achieved by using a parametric feedback scheme. We present data showing the strong dependence of the cooling of the flake's center of mass motion on the stray electric fields. We achieve this by using auxiliary electrodes to shift the position of the trap center in space. Once the point of minimum interaction between the stray fields and the particle is found (leading to cooling of the flake motion to temperatures below 20K at pressure of 10-7 Torr), we can estimate charge and mass of the flake by observing quantized discharge of the particle and measure transient dynamics of the center of mass motion by turning the cooling off and on. As an additional benefit, the behavior of the flake away from the optimum trap position can be used to quantify stray fields' effect on the particle motion by measuring its spinning orientation and frequency dependence on offset from the optimum position.

3D Printing of Polymer-Bonded Rare-Earth Magnets With a Variable Magnetic Compound Fraction for a Predefined Stray Field.

PubMed

Huber, Christian; Abert, Claas; Bruckner, Florian; Groenefeld, Martin; Schuschnigg, Stephan; Teliban, Iulian; Vogler, Christoph; Wautischer, Gregor; Windl, Roman; Suess, Dieter

2017-08-25

Additive manufacturing of polymer-bonded magnets is a recently developed technique, for single-unit production, and for structures that have been impossible to manufacture previously. Also, new possibilities to create a specific stray field around the magnet are triggered. The current work presents a method to 3D print polymer-bonded magnets with a variable magnetic compound fraction distribution. This means the saturation magnetization can be adjusted during the printing process to obtain a required external field of the manufactured magnets. A low-cost, end-user 3D printer with a mixing extruder is used to mix permanent magnetic filaments with pure polyamide (PA12) filaments. The magnetic filaments are compounded, extruded, and characterized for the printing process. To deduce the quality of the manufactured magnets with a variable magnetic compound fraction, an inverse stray field framework is developed. The effectiveness of the printing process and the simulation method is shown. It can also be used to manufacture magnets that produce a predefined stray field in a given region. This opens new possibilities for magnetic sensor applications. This setup and simulation framework allows the design and manufacturing of polymer-bonded permanent magnets, which are impossible to create with conventional methods.

Design and stray light analysis of ultra-thin geometrical waveguide

NASA Astrophysics Data System (ADS)

Wang, Qiwei; Cheng, Dewen; Hou, Qichao; Hu, Yuan; Wang, Yongtian

2015-08-01

Nowadays, the waveguide has the advantages of small thickness and light weight so that it attracts more and more attention in the field of near-eye display. However, as a major problem, stray lights generated in the waveguide seriously degrade the display quality. In this paper, a geometrical waveguide with a beam-splitting mirror array (BSMA) is designed by using the non-sequential ray-tracing software LightTools, and great efforts are paid to study the causes and solutions of the stray light. With mass calculation and optimization based on the criterion of stray light/useful light ratio, an optimum design with the least amount of stray lights is found. To further eliminate the stray light, a novel structure that couples the rays into the waveguide is designed. The optimized waveguide has a FOV of 36° in the pupil-expanding direction of the waveguide, with stray light energy reduced to 1% over the useful light, the exit pupil diameter is 11.6mm at an eye relief of 20mm and the thickness is 2.4mm.

Magnetic charge distribution and stray field landscape of asymmetric néel walls in a magnetically patterned exchange bias layer system

NASA Astrophysics Data System (ADS)

Zingsem, Norbert; Ahrend, Florian; Vock, Silvia; Gottlob, Daniel; Krug, Ingo; Doganay, Hatice; Holzinger, Dennis; Neu, Volker; Ehresmann, Arno

2017-12-01

The 3D stray field landscape above an exchange bias layer system with engineered domain walls has been fully characterized by quantitative magnetic force microscopy (qMFM) measurements. This method is based on a complete quantification of the MFM tip’s imaging properties and the subtraction of its contribution from the measured MFM data by deconvolution in Fourier space. The magnetically patterned Ir17Mn83/Co70Fe30-exchange-bias-multilayers have been designed to contain asymmetric head-to-head (hh)/tail-to-tail (tt) Néel walls between domains of different magnetic anisotropies for potential use in guided particle transport. In the current application, qMFM reveals the effective magnetic charge profile on the surface of the sample—with high spatial resolution and in an absolute quantitative manner. These data enable to calculate the magnetostatic potential and the full stray field landscape above the sample surface. It has been successfully tested against: (i) micromagnetic simulations of the magnetization structure of a comparable exchange-bias layer system, (ii) measurements of the magnetization profile across the domain boundary with x-ray photoemission electron microscopy, and (iii) direct stray field measurements obtained by scanning Hall probe microscopy at elevated scan heights. This approach results in a quantitative determination of the stray field landscape at close distances to the sample surface, which will be of importance for remote magnetic particle transport applications in lab-on-a-chip devices. Furthermore, the highly resolving and quantitative MFM approach reveals details of the domain transition across the artificially structured phase boundary, which have to be attributed to a continuous change in the materials parameters across this boundary, rather than an abrupt one.

SU-C-BRE-04: Microbeam-Radiation-Therapy (MRT): Characterizing a Novel MRT Device Using High Resolution 3D Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Q; Juang, T; Bache, S

2014-06-15

Purpose: The feasibility of MRT has recently been demonstrated utilizing a new technology of Carbon-Nano-Tube(CNT) field emission x-ray sources.This approach can deliver very high dose(10's of Gy) in narrow stripes(sub-mm) of radiation which enables the study of novel radiation treatment approaches. Here we investigate the application of highresolution (50um isotropic) PRESAGE/Optical-CT 3D dosimetry techniques to characterize the radiation delivered in this extremely dosimetrically challenging scenario. Methods: The CNT field emission x-ray source irradiator comprises of a linear cathode array and a novel collimator alignment system. This allows a precise delivery of high-energy small beams up to 160 kVp. A cylindricalmore » dosimeter (∼2.2cm in height ∼2.5cm in diameter) was irradiated by CNT MRT delivering 3 strips of radiation with a nominal entrance dose of 32 Gy.A second dosimeter was irradiated with similar entrance dose, with a regular x-ray irradiator collimated to microscopical strip-beams. 50um (isotropic) 3D dosimetry was performed using an in-house optical-CT system designed and optimized for high resolution imaging (including a stray light deconvolution correction).The percentage depth dose (PDD), peak-to-valley ratio (PVR) and beam width (FWHM) data were obtained and analyzed in both cases. Results: High resolution 3D images were successfully achieved with the prototype system, enabling extraction of PDD and dose profiles. The PDDs for the CNT irradiation showed pronounced attenuation, but less build-up effect than that from the multibeam irradiation. The beam spacing between the three strips has an average value of 0.9mm while that for the 13 strips is 1.5 mm at a depth of 16.5 mm. The stray light corrected image shows line profiles with reduced noise and consistent PVR values. Conclusion: MRT dosimetry is extremely challenging due to the ultra small fields involved.This preliminary application of a novel, ultra-high resolution, optical-CT 3D dosimetry system shows promise, but further work is required to validate and investigate accuracy and artifacts. This work was supported by NIH R01CA100835.« less

Stray light characteristics of the diffractive telescope system

NASA Astrophysics Data System (ADS)

Liu, Dun; Wang, Lihua; Yang, Wei; Wu, Shibin; Fan, Bin; Wu, Fan

2018-02-01

Diffractive telescope technology is an innovation solution in construction of large light-weight space telescope. However, the nondesign orders of diffractive optical elements (DOEs) may affect the imaging performance as stray light. To study the stray light characteristics of a diffractive telescope, a prototype was developed and its stray light analysis model was established. The stray light characteristics including ghost, point source transmittance, and veiling glare index (VGI) were analyzed. During the star imaging test of the prototype, the ghost images appeared around the star image as the exposure time of the charge-coupled device improving, consistent with the simulation results. The test result of VGI was 67.11%, slightly higher than the calculated value 57.88%. The study shows that the same order diffraction of the diffractive primary lens and correcting DOE is the main factor that causes ghost images. The stray light sources outside the field of view can illuminate the image plane through nondesign orders diffraction of the primary lens and contributes to more than 90% of the stray light flux on the image plane. In summary, it is expected that these works will provide some guidance for optimizing the imaging performance of diffractive telescopes.

Antiferromagnetic opto-spintronics

NASA Astrophysics Data System (ADS)

Němec, P.; Fiebig, M.; Kampfrath, T.; Kimel, A. V.

2018-03-01

Control and detection of spin order in ferromagnetic materials is the main principle enabling magnetic information to be stored and read in current technologies. Antiferromagnetic materials, on the other hand, are far less utilized, despite having some appealing features. For instance, the absence of net magnetization and stray fields eliminates crosstalk between neighbouring devices, and the absence of a primary macroscopic magnetization makes spin manipulation in antiferromagnets inherently faster than in ferromagnets. However, control of spins in antiferromagnets requires exceedingly high magnetic fields, and antiferromagnetic order cannot be detected with conventional magnetometry. Here we provide an overview and illustrative examples of how electromagnetic radiation can be used for probing and modification of the magnetic order in antiferromagnets. We also discuss possible research directions that are anticipated to be among the main topics defining the future of this rapidly developing field.

Proton radiation effects on the optical properties of vertically aligned carbon nanotubes

NASA Astrophysics Data System (ADS)

Kuhnhenn, J.; Khavrus, V.; Leonhardt, A.; Eversheim, D.; Noll, C.; Hinderlich, S.; Dahl, A.

2017-11-01

This paper discusses proton-induced radiation effects in vertically aligned carbon nanotubes (VA-CNT). VACNTs exhibit extremely low optical reflectivity which makes them interesting candidates for use in spacecraft stray light suppression. Investigating their behavior in space environment is a precondition for the implementation on a satellite.

L2F and LDV velocimetry measurement and analysis of the 3-D flow field in a centrifugal compressor

NASA Technical Reports Server (NTRS)

Fagan, John R., Jr.; Fleeter, Sanford

1989-01-01

The flow field in the Purdue Research Centrifugal Compressor is studied using a laser two-focus (L2F) velocimeter. L2F data are obtained which quantify: (1) the compressor inlet flow field; (2) the steady-state velocity field in the impeller blade passages; and (3) the flow field in the radial diffuser. The L2F data are compared with both laser Doppler velocimetry (LDV) data and predictions from three-dimensional inviscid and viscous flow models. In addition, a model is developed to calculate the effect on the measurement volume geometry of refraction by curved windows. Finally, the advantages and disadvantages of using the L2F for turbomachinery measurements is discussed in terms of measurement accuracy, ease of use, including sample time per correlated event and the ability to make measurements in regions of high noise due to stray radiation from wall reflections.

Microelectronics, radiation, and superconductivity.

PubMed Central

Gochfeld, M

1990-01-01

Among the costs of technology are health hazards that face employees and consumers. New advances in the highly competitive field of microelectronics involve exposure to a variety of hazards such as gallium arsenide. Small high-technology industries appear unprepared to invest in health and safety. Although stray electromagnetic fields are not a new development, researchers are beginning to assemble data indicating that such fields pose a significant cancer risk under certain circumstances. Data have been obtained on fields associated with power lines on the one hand and consumer products on the other. Although not conclusive, the data are sufficient to warrant carefully designed research into the risks posed by electromagnetic fields. Because the scientific issues require research, there is a need to make basic social value decisions that will determine which technologies will be developed and which ones may be set aside because of their danger at the present time. PMID:2401267

High Absorptance Coatings for THz Applications

NASA Technical Reports Server (NTRS)

Wollack, Edward J.

2012-01-01

High absorptance materials find application throughout the electromagnetic spectrum as radiation terminations, calibration standards, and glint reduction coatings. Successful use of materials at millimeter through submillimeter wavelengths requires an accurate knowledge and control over their thermal, mechanical, and electromagnetic properties in order to achieve the desired response while minimizing mass and volume. In practice, the achieved blackness is intimately linked to the material properties and geometry. Here, we summarize the characteristics of a variety of tunable artificial dielectric mixtures appropriate for THz applications at room and cryogenic temperatures. Theoretical guidelines for their application will be provided in the context of the effective-medium mean-field-approximation. The performance of these coatings as elements of reflectance standards, radiometric flux calibrators, passive thermal radiators, and stray light suppression baffles for imaging systems will be reviewed.

The RICH detector of the CBM experiment

NASA Astrophysics Data System (ADS)

Adamczewski-Musch, J.; Akishin, P.; Becker, K.-H.; Belogurov, S.; Bendarouach, J.; Boldyreva, N.; Deveaux, C.; Dobyrn, V.; Dürr, M.; Eschke, J.; Förtsch, J.; Heep, J.; Höhne, C.; Kampert, K.-H.; Kochenda, L.; Kopfer, J.; Kravtsov, P.; Kres, I.; Lebedev, S.; Lebedeva, E.; Leonova, E.; Linev, S.; Mahmoud, T.; Michel, J.; Miftakhov, N.; Niebur, W.; Ovcharenko, E.; Patel, V.; Pauly, C.; Pfeifer, D.; Querchfeld, S.; Rautenberg, J.; Reinecke, S.; Riabov, Y.; Roshchin, E.; Samsonov, V.; Schetinin, V.; Tarasenkova, O.; Traxler, M.; Ugur, C.; Vznuzdaev, E.; Vznuzdaev, M.

2017-12-01

The CBM-RICH detector is designed to identify electrons with momenta up to 8 GeV/c and high purity as this is essential for the CBM physics program. The detector consist of a CO2-gaseous radiator, a spherical mirror system, and Multi-Anode PhotoMultiplier Tubes (MAPMT) of type H12700 from Hamamatsu as photon detectors. The detector concept was verified through R&D studies and a laterally scaled prototype. The results were summarized in a TDR, in which open issues were defined concerning the readout electronics, the shielding of the magnetic stray field in the MAPMT region, the radiation hardness of the MAPMT sensors, and the mechanical holding structure of the mirror system. In this article an overview is given on the CBM RICH development with focus on those open issues.

Stray field signatures of Néel textured skyrmions in Ir/Fe/Co/Pt multilayer films

NASA Astrophysics Data System (ADS)

Yagil, A.; Almoalem, A.; Soumyanarayanan, Anjan; Tan, Anthony K. C.; Raju, M.; Panagopoulos, C.; Auslaender, O. M.

2018-05-01

Skyrmions are nanoscale spin configurations with topological properties that hold great promise for spintronic devices. Here, we establish their Néel texture, helicity, and size in Ir/Fe/Co/Pt multilayer films by constructing a multipole expansion to model their stray field signatures and applying it to magnetic force microscopy images. Furthermore, the demonstrated sensitivity to inhomogeneity in skyrmion properties, coupled with a unique capability to estimate the pinning force governing dynamics, portend broad applicability in the burgeoning field of topological spin textures.

Large-Format AlGaN PIN Photodiode Arrays for UV Images

NASA Technical Reports Server (NTRS)

Aslam, Shahid; Franz, David

2010-01-01

A large-format hybridized AlGaN photodiode array with an adjustable bandwidth features stray-light control, ultralow dark-current noise to reduce cooling requirements, and much higher radiation tolerance than previous technologies. This technology reduces the size, mass, power, and cost of future ultraviolet (UV) detection instruments by using lightweight, low-voltage AlGaN detectors in a hybrid detector/multiplexer configuration. The solar-blind feature eliminates the need for additional visible light rejection and reduces the sensitivity of the system to stray light that can contaminate observations.

Simulation and Measurement of Stray Light in the CLASP

NASA Technical Reports Server (NTRS)

Narukage, Noriyuki; Kano, Ryohei; Bando, Takamasa; Ishikawa, Ryoko; Kubo, Masahito; Tsuzuki, Toshihiro; Katsukawa, Yukio; Ishikawa, Shin-nosuke; Giono, Gabriel; Suematsu, Yoshinori;

A simple hand‐held magnet array for efficient and reproducible SABRE hyperpolarisation using manual sample shaking

PubMed Central

Richardson, Peter M.; Jackson, Scott; Parrott, Andrew J.; Nordon, Alison; Duckett, Simon B.

2018-01-01

Signal amplification by reversible exchange (SABRE) is a hyperpolarisation technique that catalytically transfers nuclear polarisation from parahydrogen, the singlet nuclear isomer of H2, to a substrate in solution. The SABRE exchange reaction is carried out in a polarisation transfer field (PTF) of tens of gauss before transfer to a stronger magnetic field for nuclear magnetic resonance (NMR) detection. In the simplest implementation, polarisation transfer is achieved by shaking the sample in the stray field of a superconducting NMR magnet. Although convenient, this method suffers from limited reproducibility and cannot be used with NMR spectrometers that do not have appreciable stray fields, such as benchtop instruments. Here, we use a simple hand‐held permanent magnet array to provide the necessary PTF during sample shaking. We find that the use of this array provides a 25% increase in SABRE enhancement over the stray field approach, while also providing improved reproducibility. Arrays with a range of PTFs were tested, and the PTF‐dependent SABRE enhancements were found to be in excellent agreement with comparable experiments carried out using an automated flow system where an electromagnet is used to generate the PTF. We anticipate that this approach will improve the efficiency and reproducibility of SABRE experiments carried out using manual shaking and will be particularly useful for benchtop NMR, where a suitable stray field is not readily accessible. The ability to construct arrays with a range of PTFs will also enable the rapid optimisation of SABRE enhancement as function of PTF for new substrate and catalyst systems. PMID:29193324

Cautions Concerning Electronic Analytical Balances.

ERIC Educational Resources Information Center

Johnson, Bruce B.; Wells, John D.

1986-01-01

Cautions chemists to be wary of ferromagnetic samples (especially magnetized samples), stray electromagnetic radiation, dusty environments, and changing weather conditions. These and other conditions may alter readings obtained from electronic analytical balances. (JN)

Residual stress characterization of steel TIG welds by neutron diffraction and by residual magnetic stray field mappings

NASA Astrophysics Data System (ADS)

Stegemann, Robert; Cabeza, Sandra; Lyamkin, Viktor; Bruno, Giovanni; Pittner, Andreas; Wimpory, Robert; Boin, Mirko; Kreutzbruck, Marc

2017-03-01

The residual stress distribution of tungsten inert gas welded S235JRC+C plates was determined by means of neutron diffraction (ND). Large longitudinal residual stresses with maxima around 600 MPa were found. With these results as reference, the evaluation of residual stress with high spatial resolution GMR (giant magneto resistance) sensors was discussed. The experiments performed indicate a correlation between changes in residual stresses (ND) and the normal component of local residual magnetic stray fields (GMR). Spatial variations in the magnetic field strength perpendicular to the welds are in the order of the magnetic field of the earth.

Fabrication of Compact Superconducting Lowpass Filters for Ultrasensitive Detectors

NASA Technical Reports Server (NTRS)

Brown, Ari; Chervenak, James; Chuss, David; Mikula, Vilem; Ray, Christopher; Rostem, Karwan; U-Yen, Kongpop; Wassell, Edward; Wollack, Edward

2012-01-01

It is extremely important for current and future far-infrared and sub-millimeter ultrasensitive detectors, which include transition edge sensors (TES) and microwave kinetic inductance detectors, to be adequately filtered from stray electromagnetic radiation in order to achieve their optimal performance. One means of filtering stray radiation is to block leakage associated with electrical connections in the detector environment. Here we discuss a fabrication methodology for realizing non-dissipative planar filters imbedded in the wall of the detector enclosure to limit wave propagation modes up to far-infrared frequencies. Our methodology consists of fabricating a boxed stripline transmission line, in which a superconducting (Nb, Mo, or Al) transmission line is encased in a silicon dioxide dielectric insulator coated with a metallic shell. We report on achieved attenuation and return loss and find that it replicates the simulated data to a high degree.

Calibration and evaluation of CCD spectroradiometers for ground-based and airborne measurements of spectral actinic flux densities

NASA Astrophysics Data System (ADS)

Bohn, Birger; Lohse, Insa

2017-09-01

The properties and performance of charge-coupled device (CCD) array spectroradiometers for the measurement of atmospheric spectral actinic flux densities (280-650 nm) and photolysis frequencies were investigated. These instruments are widely used in atmospheric research and are suitable for aircraft applications because of high time resolutions and high sensitivities in the UV range. The laboratory characterization included instrument-specific properties like the wavelength accuracy, dark signal, dark noise and signal-to-noise ratio (SNR). Spectral sensitivities were derived from measurements with spectral irradiance standards. The calibration procedure is described in detail, and a straightforward method to minimize the influence of stray light on spectral sensitivities is introduced. From instrument dark noise, minimum detection limits ≈ 1 × 1010 cm-2 s-1 nm-1 were derived for spectral actinic flux densities at wavelengths around 300 nm (1 s integration time). As a prerequisite for the determination of stray light under field conditions, atmospheric cutoff wavelengths were defined using radiative transfer calculations as a function of the solar zenith angle (SZA) and total ozone column (TOC). The recommended analysis of field data relies on these cutoff wavelengths and is also described in detail taking data from a research flight on HALO (High Altitude and Long Range Research Aircraft) as an example. An evaluation of field data was performed by ground-based comparisons with a double-monochromator-based, highly sensitive reference spectroradiometer. Spectral actinic flux densities were compared as well as photolysis frequencies j(NO2) and j(O1D), representing UV-A and UV-B ranges, respectively. The spectra expectedly revealed increased daytime levels of stray-light-induced signals and noise below atmospheric cutoff wavelengths. The influence of instrument noise and stray-light-induced noise was found to be insignificant for j(NO2) and rather limited for j(O1D), resulting in estimated detection limits of 5 × 10-7 and 1 × 10-7 s-1, respectively, derived from nighttime measurements on the ground (0.3 s integration time, 10 s averages). For j(O1D) the detection limit could be further reduced by setting spectral actinic flux densities to zero below atmospheric cutoff wavelengths. The accuracies of photolysis frequencies were determined from linear regressions with data from the double-monochromator reference instrument. The agreement was typically within ±5 %. Because optical-receiver aspects are not specific for the CCD spectroradiometers, they were widely excluded in this work and will be treated in a separate paper, in particular with regard to airborne applications.

A simple hand-held magnet array for efficient and reproducible SABRE hyperpolarisation using manual sample shaking.

PubMed

Richardson, Peter M; Jackson, Scott; Parrott, Andrew J; Nordon, Alison; Duckett, Simon B; Halse, Meghan E

2018-07-01

Signal amplification by reversible exchange (SABRE) is a hyperpolarisation technique that catalytically transfers nuclear polarisation from parahydrogen, the singlet nuclear isomer of H 2 , to a substrate in solution. The SABRE exchange reaction is carried out in a polarisation transfer field (PTF) of tens of gauss before transfer to a stronger magnetic field for nuclear magnetic resonance (NMR) detection. In the simplest implementation, polarisation transfer is achieved by shaking the sample in the stray field of a superconducting NMR magnet. Although convenient, this method suffers from limited reproducibility and cannot be used with NMR spectrometers that do not have appreciable stray fields, such as benchtop instruments. Here, we use a simple hand-held permanent magnet array to provide the necessary PTF during sample shaking. We find that the use of this array provides a 25% increase in SABRE enhancement over the stray field approach, while also providing improved reproducibility. Arrays with a range of PTFs were tested, and the PTF-dependent SABRE enhancements were found to be in excellent agreement with comparable experiments carried out using an automated flow system where an electromagnet is used to generate the PTF. We anticipate that this approach will improve the efficiency and reproducibility of SABRE experiments carried out using manual shaking and will be particularly useful for benchtop NMR, where a suitable stray field is not readily accessible. The ability to construct arrays with a range of PTFs will also enable the rapid optimisation of SABRE enhancement as function of PTF for new substrate and catalyst systems. © 2017 The Authors Magnetic Resonance in Chemistry Published by John Wiley & Sons Ltd.

Baffles design of the PROBA-V wide FOV TMA

NASA Astrophysics Data System (ADS)

Mazzoli, A.; Holbrouck, P.; Houbrechts, Y.; Maresi, L.; Stockman, Y.; Taccola, M.; Versluys, J.

2017-11-01

Proba-V payload is a successor of the Vegetation instrument, a multispectral imager flown on Spot-4 and subsequently on Spot-5, French satellites for Earth Observation and defence. The instrument, with its wide field of view, is capable of covering a swath of 2200 km, which, in combination with a polar low Earth orbit, guarantees a daily revisit. The lifetime of Spot-5 expires in early 2013, and to ensure the continuity of vegetation data, BELSPO, the Belgian Federal Science Policy Office, supported the development of an instrument that could be flown on a Proba type satellite, a small satellite developed by the Belgian QinetiQ Space (previously known as Verhaert Space). The challenge of this development is to produce an instrument responding to the same user requirements as Vegetation, but with an overall mass of about 30 kg, while the Vegetation instrument mass is 130 kg. This development had become feasible thanks to a number of new technologies that have been developed since the nineties, when Vegetation was first conceived, namely Single Point Diamond Turning fabrication of aspherical mirrors and efficient VNIR and SWIR detectors. The Proba-V payload is based on three identical reflective telescopes using highly aspherical mirrors in a TMA (Three Mirrors Anastigmat) configuration. Each telescope covers a field of view of 34° to reach the required swath. One of the challenges in the development of the PROBA-V instrument is the efficient reduction of stray light. Due to the mass and volume constraints it was not possible to implement a design with an intermediate focus to reduce the stray light. The analysis and minimization of the in-field stray light is an important element of the design because of the large FOV and the surface roughness currently achievable with the Single Point Diamond Turning. This document presents the preliminary baffle layout designed for the Three Mirrors Anastigmatic (TMA) telescope developed for the Proba-V mission. This baffling is used to avoid 1st order stray light i.e. direct stray light or through reflections on the mirrors. The stray light from the SWIR folding mirror is also studied. After these preliminary analyses the mechanical structure of the TMA is designed then verified in term of vignetting and stray light.

A fast finite-difference algorithm for topology optimization of permanent magnets

NASA Astrophysics Data System (ADS)

Abert, Claas; Huber, Christian; Bruckner, Florian; Vogler, Christoph; Wautischer, Gregor; Suess, Dieter

2017-09-01

We present a finite-difference method for the topology optimization of permanent magnets that is based on the fast-Fourier-transform (FFT) accelerated computation of the stray-field. The presented method employs the density approach for topology optimization and uses an adjoint method for the gradient computation. Comparison to various state-of-the-art finite-element implementations shows a superior performance and accuracy. Moreover, the presented method is very flexible and easy to implement due to various preexisting FFT stray-field implementations that can be used.

Superluminal antenna

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singleton, John; Earley, Lawrence M.; Krawczyk, Frank L.

A superluminal antenna element integrates a balun element to better impedance match an input cable or waveguide to a dielectric radiator element, thus preventing stray reflections and consequent undesirable radiation. For example, a dielectric housing material can be used that has a cutout area. A cable can extend into the cutout area. A triangular conductor can function as an impedance transition. An additional cylindrical element functions as a sleeve balun to better impedance match the radiator element to the cable.

Superluminal antenna

DOEpatents

Singleton, John; Earley, Lawrence M.; Krawczyk, Frank L.; Potter, James M.; Romero, William P.; Wang, Zhi-Fu

2018-04-17

A superluminal antenna element integrates a balun element to better impedance match an input cable or waveguide to a dielectric radiator element, thus preventing stray reflections and consequent undesirable radiation. For example, a dielectric housing material can be used that has a cutout area. A cable can extend into the cutout area. A triangular conductor can function as an impedance transition. An additional cylindrical element functions as a sleeve balun to better impedance match the radiator element to the cable.

Proton therapy versus intensity modulated x-ray therapy in the treatment of prostate cancer: Estimating secondary cancer risks

NASA Astrophysics Data System (ADS)

Fontenot, Jonas David

External beam radiation therapy is used to treat nearly half of the more than 200,000 new cases of prostate cancer diagnosed in the United States each year. During a radiation therapy treatment, healthy tissues in the path of the therapeutic beam are exposed to high doses. In addition, the whole body is exposed to a low-dose bath of unwanted scatter radiation from the pelvis and leakage radiation from the treatment unit. As a result, survivors of radiation therapy for prostate cancer face an elevated risk of developing a radiogenic second cancer. Recently, proton therapy has been shown to reduce the dose delivered by the therapeutic beam to normal tissues during treatment compared to intensity modulated x-ray therapy (IMXT, the current standard of care). However, the magnitude of stray radiation doses from proton therapy, and their impact on this incidence of radiogenic second cancers, was not known. The risk of a radiogenic second cancer following proton therapy for prostate cancer relative to IMXT was determined for 3 patients of large, median, and small anatomical stature. Doses delivered to healthy tissues from the therapeutic beam were obtained from treatment planning system calculations. Stray doses from IMXT were taken from the literature, while stray doses from proton therapy were simulated using a Monte Carlo model of a passive scattering treatment unit and an anthropomorphic phantom. Baseline risk models were taken from the Biological Effects of Ionizing Radiation VII report. A sensitivity analysis was conducted to characterize the uncertainty of risk calculations to uncertainties in the risk model, the relative biological effectiveness (RBE) of neutrons for carcinogenesis, and inter-patient anatomical variations. The risk projections revealed that proton therapy carries a lower risk for radiogenic second cancer incidence following prostate irradiation compared to IMXT. The sensitivity analysis revealed that the results of the risk analysis depended only weakly on uncertainties in the risk model and inter-patient variations. Second cancer risks were sensitive to changes in the RBE of neutrons. However, the findings of the study were qualitatively consistent for all patient sizes and risk models considered, and for all neutron RBE values less than 100.

Stray light effects in above-water remote-sensing reflectance from hyperspectral radiometers.

PubMed

Talone, Marco; Zibordi, Giuseppe; Ansko, Ilmar; Banks, Andrew Clive; Kuusk, Joel

2016-05-20

Stray light perturbations are unwanted distortions of the measured spectrum due to the nonideal performance of optical radiometers. Because of this, stray light characterization and correction is essential when accurate radiometric measurements are a necessity. In agreement with such a need, this study focused on stray light correction of hyperspectral radiometers widely applied for above-water measurements to determine the remote-sensing reflectance (R_RS). Stray light of sample radiometers was experimentally characterized and a correction algorithm was developed and applied to field measurements performed in the Mediterranean Sea. Results indicate that mean stray light corrections are appreciable, with values generally varying from -1% to +1% in the 400-700 nm spectral region for downward irradiance and sky radiance, and from -1% to +4% for total radiance from the sea. Mean corrections for data products such as R_RS exhibit values that depend on water type varying between -0.5% and +1% in the blue-green spectral region, with peaks up to 9% in the red in eutrophic waters. The possibility of using one common stray light correction matrix for the analyzed class of radiometers was also investigated. Results centered on R_RS support such a feasibility at the expense of an increment of the uncertainty typically well below 0.5% in the blue-green and up to 1% in the red, assuming sensors are based on spectrographs from the same production batch.

Instrument intercomparison in the high-energy mixed field at the CERN-EU reference field (CERF) facility.

PubMed

Caresana, Marco; Helmecke, Manuela; Kubancak, Jan; Manessi, Giacomo Paolo; Ott, Klaus; Scherpelz, Robert; Silari, Marco

2014-10-01

This paper discusses an intercomparison campaign performed in the mixed radiation field at the CERN-EU (CERF) reference field facility. Various instruments were employed: conventional and extended-range rem counters including a novel instrument called LUPIN, a bubble detector using an active counting system (ABC 1260) and two tissue-equivalent proportional counters (TEPCs). The results show that the extended range instruments agree well within their uncertainties and within 1σ with the H*(10) FLUKA value. The conventional rem counters are in good agreement within their uncertainties and underestimate H*(10) as measured by the extended range instruments and as predicted by FLUKA. The TEPCs slightly overestimate the FLUKA value but they are anyhow consistent with it when taking the comparatively large total uncertainties into account, and indicate that the non-neutron part of the stray field accounts for ∼30 % of the total H*(10). © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Sensitization of a stray-field NMR to vibrations: a potential for MR elastometry with a portable NMR sensor.

PubMed

Mastikhin, Igor; Barnhill, Marie

2014-11-01

An NMR signal from a sample in a constant stray field of a portable NMR sensor is sensitized to vibrations. The CPMG sequence is synchronized to vibrations so that the constant gradient becomes an "effective" square-wave gradient, leading to the vibration-induced phase accumulation. The integrating nature of the spot measurement, combined with the phase distribution due to a non-uniform gradient and/or a wave field, leads to a destructive interference, the drop in the signal intensity and changes in the echo train shape. Vibrations with amplitudes as small as 140 nm were reliably detected with the permanent gradient of 12.4 T/m. The signal intensity depends on the phase offset between the vibrations and the pulse sequence. This approach opens the way for performing elastometry and micro-rheology measurements with portable NMR devices beyond the walls of a laboratory. Even without synchronization, if a vibration frequency is comparable to 1/2TE of the CPMG sequence, the signal can be severely affected, making it important for potential industrial applications of stray-field NMR. Copyright © 2014 Elsevier Inc. All rights reserved.

Model of inter-cell interference phenomenon in 10 nm magnetic tunnel junction with perpendicular anisotropy array due to oscillatory stray field from neighboring cells

NASA Astrophysics Data System (ADS)

Ohuchida, Satoshi; Endoh, Tetsuo

2018-06-01

In this paper, we propose a new model of inter-cell interference phenomenon in a 10 nm magnetic tunnel junction with perpendicular anisotropy (p-MTJ) array and investigated the interference effect between a program cell and unselected cells due to the oscillatory stray field from neighboring cells by Landau–Lifshitz–Gilbert micromagnetic simulation. We found that interference brings about a switching delay in a program cell and excitation of magnetization precession in unselected cells even when no programing current passes through. The origin of interference is ferromagnetic resonance between neighboring cells. During the interference period, the precession frequency of the program cell is 20.8 GHz, which synchronizes with that of the theoretical precession frequency f = γH eff in unselected cells. The disturbance strength of unselected cells decreased to be inversely proportional to the cube of the distance from the program cell, which is in good agreement with the dependence of stray field on the distance from the program cell calculated by the dipole approximation method.

The ASTRO-H SXT Performance to the Large Off-Set Angles

NASA Technical Reports Server (NTRS)

Sato, Toshiki; Iizuka, Ryo; Mori, Hideyuki; Hayashi, Takayuki; Maeda, Yoshitomo; Ishida, Manabu; Kikuchi, Naomichi; Kurashima, Sho; Nakaniwa, Nozomi; Okajima, Takashi;

Electromagnetically Induced Transparency Experiments for the Advanced Undergraduate Laboratory: Suppression of Polarization Impurity and Stray Magnetic Fields

NASA Astrophysics Data System (ADS)

Campbell, Kaleb; Jackson, Richard; van Vleet, Matthew; Kuhnash, Kodi; Worth, Bradley; Day, Amanda; Bali, Samir

2014-05-01

We investigate electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) in rubidium vapor using a single laser beam and a scanning magnetic field co-aligned with the laser propagation direction. We show that polarization impurity, stray magnetic fields and imperfect optical alignments cause broadening of the EIT/EIA signal and other spurious effects. We describe a systematic approach to minimizing these undesired effects, which produces EIT/EIA signals nearly two orders of magnitude narrower than the natural linewidth. We gratefully acknowledge funding from the American Chemical Society Petroleum Research Fund and Miami University. We also acknowledge the Miami University Instrumentation Laboratory for their invaluable contributions.

WE-D-17A-05: Measurement of Stray Radiation Within An Active Scanning Proton Therapy Facility: EURADOS WG9 Intercomparison Exercise of Active Dosimetry Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farah, J; Trompier, F; Stolarczyk, L

2014-06-15

Purpose: Intercomparison of active dosemeters in the measurement of stray radiation at the Trento active-scanning proton therapy facility. Methods: EURADOS WG9 carried out a large intercomparison exercise to test different dosemeters while measuring secondary neutrons within a 230 MeV scanned proton therapy facility. Detectors included two Bonner Sphere Spectrometers (BSS), three tissue equivalent proportional counters (TEPCHawk) and six rem-counters (Wendi II, Berthold, RadEye, a regular and an extended-range Anderson and Braun NM2B counters). Measurements of neutron ambient dose equivalents, H*(10), were done at several positions inside (8 positions) and outside (3 positions) the treatment room while irradiating a water tankmore » phantom with a 10 × 10 × 10 cc field. Results: A generally good agreement on H*(10) values was observed for the tested detectors. At distance of 2.25 m and angles 45°, 90° and 180° with respect to the beam axis, BSS and proportional counters agreed within 30%. Higher differences (up to 60%) were observed at the closest and farthest distances, i.e. at positions where detectors sensitivity, energy, fluence and angular response are highly dependent on neutron spectra (flux and energy). The highest neutron H*(10) value, ∼60 microSv/Gy, was measured at 1.15 m along the beam axis. H*(10) decreased significantly with the distance from the isocenter dropping to 1.1 microSv/Gy at 4.25 m and 90° from beam axis, ∼2 nanoSv/Gy at the entrance of the maze, 0.2 nanoSv/Gy at the door outside the room and below detection limit in the gantry control room and at an adjacent room. These values remain considerately lower than those of passively scattered proton beams. BSS and Hawk unfolded spectra provide valuable inputs when studying the response of each detector. Conclusion: TEPCs and BSS enable accurate measurements of stray neutrons while other rem-meters also give satisfactory results but require further improvements to reduce uncertainties.« less

First results from protective ECRH diagnostics for Wendelstein 7-X

NASA Astrophysics Data System (ADS)

Marsen, S.; Corre, Y.; Laqua, H. P.; Moncada, V.; Moseev, D.; Niemann, H.; Preynas, M.; Stange, T.; The W7-X Team

2017-08-01

Wendelstein 7-X (W7-X) is a steady state capable optimised stellarator. The main heating system is electron cyclotron resonance heating (ECRH) operating at 140 GHz providing up to 9 MW microwave power. The power is launched into the machine by front steerable quasi-optical launchers in X- or O-mode. While in X-mode the first pass absorption is 99%, it is only 40... 70% in O-mode. O2-mode heating is forseen for high density operation above the X2 cutoff density of 1.2\\centerdot {{10}20} m-3. A set of diagnostics has been developed to protect the machine from non absorbed ECRH power which can easily damage in vessel components. The non absorbed power hitting the inner wall is measured by waveguides embedded in the first wall (ECA diagnostic). In order to prevent the inner wall from overheating or arcing, a near-infra red sensitive video diagnostic with a dynamic range of 450...1200 °C was integrated in the ECRH launchers. Thermal calculations for the carbon tiles predict a temperature increase above the detection threshold for scenarios of plasma start-up failure or poor absorption on a time scale of 50 ms. However, the temperature increase measured by an IR camera in experiments with failed break down, i.e. no ECRH absorption for up to 50 ms, was only Δ T≈ 70{{~}\\circ} C. In discharges with ≈ 5% transmission the measured temperature increase was comparable. The stray radiation level inside the machine is measured by so called sniffer probes resembling microwave diode detectors which were designed to collect all radiation approaching the probing surface independent of incident angle and polarization. Five sniffer probes are installed at different toroidal positions. They were integrated in the ECRH interlock system. During the first operational phase of W7-X this was the only available plasma interlock system. The signal quality proofed to be high enough for a reliable termination in case of poor absorption. After a breakdown phase of 10 ms, the sniffer probe signals dropped by more than an order of magnitude. Especially in the very first days of operation, most discharges died by a radiative collapse due to impurity influx. In this case the heating power was reliably switched off due to the increased level of stray radiation. Moreover, ECRH bolometers with a slower response time in the launcher ports and an empty diagnostic port were used to estimate the stray radiation level in the ports. In the launcher ports it could be shown that the stray radiation could lead to an overheating of the bellows in long discharges. Possible counter measures are discussed.

Comparison of Eight Years Total Column Ozone Retrievals form Brewer and Dobson Spectrophotometers in South Pole

NASA Astrophysics Data System (ADS)

Feng, K. H.; Moeini, O.; McElroy, C. T.; Evans, R. D.; Petropavlovskikh, I. V.

2015-12-01

Total column ozone measured by a Brewer Mark III spectrophotometer (#85) from 2008 to 2015 is compared to the data obtained from three different Dobson spectrophotometers (#80, #82 and #42) that have been operating in parallel with the Brewer at the Amundsen-Scott Station near the South Pole. Measurements are made using either direct sunlight or light from the moon (up to 2 weeks per month). The result of the comparison was used to assess the performance of the two instrument types and determine the stability of the measurement systems. Both instruments suffer from non-linearity due to the presence of instrumental stray light caused by the out-off-band radiations scattered from the optics within the instrument. Stray light results in an underestimated ozone column at large ozone path lengths. Since measurements made at the location of the station (Latitude 89.99o, Longitude -24.80o) have solar zenith angles of 66.5 degrees or greater, the issue of stray light is a particular concern.

Development of Numerical Methods to Estimate the Ohmic Breakdown Scenarios of a Tokamak

NASA Astrophysics Data System (ADS)

Yoo, Min-Gu; Kim, Jayhyun; An, Younghwa; Hwang, Yong-Seok; Shim, Seung Bo; Lee, Hae June; Na, Yong-Su

2011-10-01

The ohmic breakdown is a fundamental method to initiate the plasma in a tokamak. For the robust breakdown, ohmic breakdown scenarios have to be carefully designed by optimizing the magnetic field configurations to minimize the stray magnetic fields. This research focuses on development of numerical methods to estimate the ohmic breakdown scenarios by precise analysis of the magnetic field configurations. This is essential for the robust and optimal breakdown and start-up of fusion devices especially for ITER and its beyond equipped with low toroidal electric field (ET <= 0.3 V/m). A field-line-following analysis code based on the Townsend avalanche theory and a particle simulation code are developed to analyze the breakdown characteristics of actual complex magnetic field configurations including the stray magnetic fields in tokamaks. They are applied to the ohmic breakdown scenarios of tokamaks such as KSTAR and VEST and compared with experiments.

Stray light lessons learned from the Mars reconnaissance orbiter's optical navigation camera

NASA Astrophysics Data System (ADS)

Lowman, Andrew E.; Stauder, John L.

2004-10-01

The Optical Navigation Camera (ONC) is a technical demonstration slated to fly on NASA"s Mars Reconnaissance Orbiter in 2005. Conventional navigation methods have reduced accuracy in the days immediately preceding Mars orbit insertion. The resulting uncertainty in spacecraft location limits rover landing sites to relatively safe areas, away from interesting features that may harbor clues to past life on the planet. The ONC will provide accurate navigation on approach for future missions by measuring the locations of the satellites of Mars relative to background stars. Because Mars will be a bright extended object just outside the camera"s field of view, stray light control at small angles is essential. The ONC optomechanical design was analyzed by stray light experts and appropriate baffles were implemented. However, stray light testing revealed significantly higher levels of light than expected at the most critical angles. The primary error source proved to be the interface between ground glass surfaces (and the paint that had been applied to them) and the polished surfaces of the lenses. This paper will describe troubleshooting and correction of the problem, as well as other lessons learned that affected stray light performance.

A comprehensive spectrometry study of a stray neutron radiation field in scanning proton therapy.

PubMed

Mares, Vladimir; Romero-Expósito, Maite; Farah, Jad; Trinkl, Sebastian; Domingo, Carles; Dommert, Martin; Stolarczyk, Liliana; Van Ryckeghem, Laurent; Wielunski, Marek; Olko, Pawel; Harrison, Roger M

2016-06-07

The purpose of this study is to characterize the stray neutron radiation field in scanning proton therapy considering a pediatric anthropomorphic phantom and a clinically-relevant beam condition. Using two extended-range Bonner sphere spectrometry systems (ERBSS), Working Group 9 of the European Radiation Dosimetry Group measured neutron spectra at ten different positions around a pediatric anthropomorphic phantom irradiated for a brain tumor with a scanning proton beam. This study compares the different systems and unfolding codes as well as neutron spectra measured in similar conditions around a water tank phantom. The ten spectra measured with two ERBSS systems show a generally similar thermal component regardless of the position around the phantom while high energy neutrons (above 20 MeV) were only registered at positions near the beam axis (at 0°, 329° and 355°). Neutron spectra, fluence and ambient dose equivalent, H (*)(10), values of both systems were in good agreement (<15%) while the unfolding code proved to have a limited effect. The highest H (*)(10) value of 2.7 μSv Gy(-1) was measured at 329° to the beam axis and 1.63 m from the isocenter where high-energy neutrons (E  ⩾  20 MeV) contribute with about 53%. The neutron mapping within the gantry room showed that H (*)(10) values significantly decreased with distance and angular position with respect to the beam axis dropping to 0.52 μSv Gy(-1) at 90° and 3.35 m. Spectra at angles of 45° and 135° with respect to the beam axis measured here with an anthropomorphic phantom showed a similar peak structure at the thermal, fast and high energy range as in the previous water-tank experiments. Meanwhile, at 90°, small differences at the high-energy range were observed. Using ERBSS systems, neutron spectra mapping was performed to characterize the exposure of scanning proton therapy patients. The ten measured spectra provide precise information about the exposure of healthy organs to thermal, epithermal, evaporation and intra-nuclear cascade neutrons. This comprehensive spectrometry analysis can also help in understanding the tremendous literature data based rem-counters while also being of great value for general neutron shielding and radiation safety studies.

A star tracker insensitive to stray light generated by radiation sources close to the field of view

NASA Astrophysics Data System (ADS)

Romoli, A.; Gambicorti, L.; Simonetti, F.; Zuccaro Marchi, A.

2017-11-01

Aim of this work is to propose an innovative star tracker, practically insensitive to the radiation coming from the sun or from other strong planetary sources out of (but near) the Field of View. These sources need to be stopped in some way. The classical solution to reject the unwanted radiation is to place a shadow (or baffle) before the star tracker objective. The shadow size depends on the Field of View and on the minimum angle subtended by the source (i.e. the sun) with respect to the optical axis of the star tracker. The lower is this angle the larger is the shadow. Requests for star trackers able to work with the sun as close as possible to the Field of View are increasing, due to the need of maximum mission flexibility. The innovation of this proposed star tracker is conceived by using spatial filtering with a concept complementary to that of coronagraph for sun corona observation, allowing to drastically reduce the size of the shadow. It can also work close to antennas and other part of the platform, which, when illuminated by the sun, become secondary sources capable to blind the star tracker. This kind of accommodation offers three main advantages: no cumbersome shadows (baffle), maximum flexibility in terms of mission profile, less platform location constraints. This new star sensor concept, dated 2007, is now patent pending. Galileo Avionica (now Selex Galileo) is the owner of the patent.

Adaptive quantum computation in changing environments using projective simulation

NASA Astrophysics Data System (ADS)

Tiersch, M.; Ganahl, E. J.; Briegel, H. J.

2015-08-01

Quantum information processing devices need to be robust and stable against external noise and internal imperfections to ensure correct operation. In a setting of measurement-based quantum computation, we explore how an intelligent agent endowed with a projective simulator can act as controller to adapt measurement directions to an external stray field of unknown magnitude in a fixed direction. We assess the agent’s learning behavior in static and time-varying fields and explore composition strategies in the projective simulator to improve the agent’s performance. We demonstrate the applicability by correcting for stray fields in a measurement-based algorithm for Grover’s search. Thereby, we lay out a path for adaptive controllers based on intelligent agents for quantum information tasks.

Adaptive quantum computation in changing environments using projective simulation

PubMed Central

Tiersch, M.; Ganahl, E. J.; Briegel, H. J.

2015-01-01

Quantum information processing devices need to be robust and stable against external noise and internal imperfections to ensure correct operation. In a setting of measurement-based quantum computation, we explore how an intelligent agent endowed with a projective simulator can act as controller to adapt measurement directions to an external stray field of unknown magnitude in a fixed direction. We assess the agent’s learning behavior in static and time-varying fields and explore composition strategies in the projective simulator to improve the agent’s performance. We demonstrate the applicability by correcting for stray fields in a measurement-based algorithm for Grover’s search. Thereby, we lay out a path for adaptive controllers based on intelligent agents for quantum information tasks. PMID:26260263

Design of an ultra-thin near-eye display with geometrical waveguide and freeform optics.

PubMed

Cheng, Dewen; Wang, Yongtian; Xu, Chen; Song, Weitao; Jin, Guofan

2014-08-25

Small thickness and light weight are two important requirements for a see-through near-eye display which are achieved in this paper by using two advanced technologies: geometrical waveguide and freeform optics. A major problem associated with the geometrical waveguide is the stray light which can severely degrade the display quality. The causes and solutions to this problem are thoroughly studied. A mathematical model of the waveguide is established and a non-sequential ray tracing algorithm is developed, which enable us to carefully examine the stray light of the planar waveguide and explore a global searching method to find an optimum design with the least amount of stray light. A projection optics using freeform surfaces on a wedge shaped prism is also designed. The near-eye display integrating the projection optics and the waveguide has a field of view of 28°, an exit pupil diameter of 9.6mm and an exit pupil distance of 20mm. In our final design, the proportion of the stray light energy over the image output energy of the waveguide is reduced to 2%, the modulation transfer function values across the entire field of the eyepiece are above 0.5 at 30 line pairs/mm (lps/mm). A proof-of-concept prototype of the proposed geometrical waveguide near-eye display is developed and demonstrated.

Antiferromagnetic CuMnAs multi-level memory cell with microelectronic compatibility

NASA Astrophysics Data System (ADS)

Olejník, K.; Schuler, V.; Marti, X.; Novák, V.; Kašpar, Z.; Wadley, P.; Campion, R. P.; Edmonds, K. W.; Gallagher, B. L.; Garces, J.; Baumgartner, M.; Gambardella, P.; Jungwirth, T.

2017-05-01

Antiferromagnets offer a unique combination of properties including the radiation and magnetic field hardness, the absence of stray magnetic fields, and the spin-dynamics frequency scale in terahertz. Recent experiments have demonstrated that relativistic spin-orbit torques can provide the means for an efficient electric control of antiferromagnetic moments. Here we show that elementary-shape memory cells fabricated from a single-layer antiferromagnet CuMnAs deposited on a III-V or Si substrate have deterministic multi-level switching characteristics. They allow for counting and recording thousands of input pulses and responding to pulses of lengths downscaled to hundreds of picoseconds. To demonstrate the compatibility with common microelectronic circuitry, we implemented the antiferromagnetic bit cell in a standard printed circuit board managed and powered at ambient conditions by a computer via a USB interface. Our results open a path towards specialized embedded memory-logic applications and ultra-fast components based on antiferromagnets.

Micromagnetic Architectures for On-chip Microparticle Transport

NASA Astrophysics Data System (ADS)

Ouk, Minae; Beach, Geoffrey S. D.

2015-03-01

Superparamagnetic microbeads (SBs) are widely used to capture and manipulate biological entities in a fluid environment. Chip-based magnetic actuation provides a means to transport SBs in lab-on-a-chip devices. This is usually accomplished using the stray field from patterned magnetic microstructures, or domain walls in magnetic nanowires. Magnetic anti-dot arrays are particularly attractive due to the high-gradient stray fields from their partial domain wall structures. Here we use a self-assembly method to create magnetic anti-dot arrays in Co films, and describe the motion of SBs across the surface by a rotating field. We find a critical field-rotation frequency beyond which bead motion ceases and a critical threshold for both the in-plane and out-of-plane field components that must be exceeded for bead motion to occur. We show that these field thresholds are bead size dependent, and can thus be used to digitally separate magnetic beads in multi-bead populations. Hence these large-area structures can be used to combine long distance transport with novel functionalities.

The direct injection of intense ion beams from a high field electron cyclotron resonance ion source into a radio frequency quadrupole

NASA Astrophysics Data System (ADS)

Rodrigues, G.; Becker, R.; Hamm, R. W.; Baskaran, R.; Kanjilal, D.; Roy, A.

2014-02-01

The ion current achievable from high intensity ECR sources for highly charged ions is limited by the high space charge. This makes classical extraction systems for the transport and subsequent matching to a radio frequency quadrupole (RFQ) accelerator less efficient. The direct plasma injection (DPI) method developed originally for the laser ion source avoids these problems and uses the combined focusing of the gap between the ion source and the RFQ vanes (or rods) and the focusing of the rf fields from the RFQ penetrating into this gap. For high performance ECR sources that use superconducting solenoids, the stray magnetic field of the source in addition to the DPI scheme provides focusing against the space charge blow-up of the beam. A combined extraction/matching system has been designed for a high performance ECR ion source injecting into an RFQ, allowing a total beam current of 10 mA from the ion source for the production of highly charged 238U40+ (1.33 mA) to be injected at an ion source voltage of 60 kV. In this design, the features of IGUN have been used to take into account the rf-focusing of an RFQ channel (without modulation), the electrostatic field between ion source extraction and the RFQ vanes, the magnetic stray field of the ECR superconducting solenoid, and the defocusing space charge of an ion beam. The stray magnetic field is shown to be critical in the case of a matched beam.

The direct injection of intense ion beams from a high field electron cyclotron resonance ion source into a radio frequency quadrupole.

PubMed

Rodrigues, G; Becker, R; Hamm, R W; Baskaran, R; Kanjilal, D; Roy, A

2014-02-01

The ion current achievable from high intensity ECR sources for highly charged ions is limited by the high space charge. This makes classical extraction systems for the transport and subsequent matching to a radio frequency quadrupole (RFQ) accelerator less efficient. The direct plasma injection (DPI) method developed originally for the laser ion source avoids these problems and uses the combined focusing of the gap between the ion source and the RFQ vanes (or rods) and the focusing of the rf fields from the RFQ penetrating into this gap. For high performance ECR sources that use superconducting solenoids, the stray magnetic field of the source in addition to the DPI scheme provides focusing against the space charge blow-up of the beam. A combined extraction/matching system has been designed for a high performance ECR ion source injecting into an RFQ, allowing a total beam current of 10 mA from the ion source for the production of highly charged (238)U(40+) (1.33 mA) to be injected at an ion source voltage of 60 kV. In this design, the features of IGUN have been used to take into account the rf-focusing of an RFQ channel (without modulation), the electrostatic field between ion source extraction and the RFQ vanes, the magnetic stray field of the ECR superconducting solenoid, and the defocusing space charge of an ion beam. The stray magnetic field is shown to be critical in the case of a matched beam.

Multiwalled carbon nanotubes for stray light suppression in space flight instruments

NASA Astrophysics Data System (ADS)

Hagopian, John G.; Getty, Stephanie A.; Quijada, Manuel; Tveekrem, June; Shiri, Ron; Roman, Patrick; Butler, James; Georgiev, Georgi; Livas, Jeff; Hunt, Cleophus; Maldonado, Alejandro; Talapatra, Saikat; Zhang, Xianfeng; Papadakis, Stergios J.; Monica, Andrew H.; Deglau, David

2010-08-01

Observations of the Earth are extremely challenging; its large angular extent floods scientific instruments with high flux within and adjacent to the desired field of view. This bright light diffracts from instrument structures, rattles around and invariably contaminates measurements. Astrophysical observations also are impacted by stray light that obscures very dim objects and degrades signal to noise in spectroscopic measurements. Stray light is controlled by utilizing low reflectance structural surface treatments and by using baffles and stops to limit this background noise. In 2007 GSFC researchers discovered that Multiwalled Carbon Nanotubes (MWCNTs) are exceptionally good absorbers, with potential to provide order-of-magnitude improvement over current surface treatments and a resulting factor of 10,000 reduction in stray light when applied to an entire optical train. Development of this technology will provide numerous benefits including: a.) simplification of instrument stray light controls to achieve equivalent performance, b.) increasing observational efficiencies by recovering currently unusable scenes in high contrast regions, and c.) enabling low-noise observations that are beyond current capabilities. Our objective was to develop and apply MWCNTs to instrument components to realize these benefits. We have addressed the technical challenges to advance the technology by tuning the MWCNT geometry using a variety of methods to provide a factor of 10 improvement over current surface treatments used in space flight hardware. Techniques are being developed to apply the optimized geometry to typical instrument components such as spiders, baffles and tubes. Application of the nanostructures to alternate materials (or by contact transfer) is also being investigated. In addition, candidate geometries have been tested and optimized for robustness to survive integration, testing, launch and operations associated with space flight hardware. The benefits of this technology extend to space science where observations of extremely dim objects require suppression of stray light.

3D print of polymer bonded rare-earth magnets, and 3D magnetic field scanning with an end-user 3D printer

NASA Astrophysics Data System (ADS)

Huber, C.; Abert, C.; Bruckner, F.; Groenefeld, M.; Muthsam, O.; Schuschnigg, S.; Sirak, K.; Thanhoffer, R.; Teliban, I.; Vogler, C.; Windl, R.; Suess, D.

2016-10-01

3D print is a recently developed technique, for single-unit production, and for structures that have been impossible to build previously. The current work presents a method to 3D print polymer bonded isotropic hard magnets with a low-cost, end-user 3D printer. Commercially available isotropic NdFeB powder inside a PA11 matrix is characterized, and prepared for the printing process. An example of a printed magnet with a complex shape that was designed to generate a specific stray field is presented, and compared with finite element simulation solving the macroscopic Maxwell equations. For magnetic characterization, and comparing 3D printed structures with injection molded parts, hysteresis measurements are performed. To measure the stray field outside the magnet, the printer is upgraded to a 3D magnetic flux density measurement system. To skip an elaborate adjusting of the sensor, a simulation is used to calibrate the angles, sensitivity, and the offset of the sensor. With this setup, a measurement resolution of 0.05 mm along the z-axes is achievable. The effectiveness of our calibration method is shown. With our setup, we are able to print polymer bonded magnetic systems with the freedom of having a specific complex shape with locally tailored magnetic properties. The 3D scanning setup is easy to mount, and with our calibration method we are able to get accurate measuring results of the stray field.

Identification and mitigation of stray laser light in the Thomson scattering system on the Madison Symmetric Torus (MST).

PubMed

Jacobson, C M; Borchardt, M T; Den Hartog, D J; Falkowski, A F; Morton, L A; Thomas, M A

2016-11-01

The Thomson scattering diagnostic on the Madison Symmetric Torus (MST) records excessive levels of stray Nd:YAG laser light. Stray light saturates the 1064 nm spectral channel in all polychromators, which prevents absolute electron density measurements via Rayleigh scattering calibration. Furthermore, stray light contaminates adjacent spectral channels for r/a ≥ 0.75, which renders the diagnostic unable to make electron temperature measurements at these radii. In situ measurements of stray light levels during a vacuum vessel vent are used to identify stray light sources and strategies for reduction of stray light levels. Numerical modeling using Zemax OpticStudio supports these measurements. The model of the vacuum vessel and diagnostic includes synthetic collection optics to enable direct comparison of measured and simulated stray light levels. Modeling produces qualitatively similar stray light distributions to MST measurements, and quantifies the mitigation effects of stray light mitigation strategies prior to implementation.

Identification and mitigation of stray laser light in the Thomson scattering system on the Madison Symmetric Torus (MST)

NASA Astrophysics Data System (ADS)

Jacobson, C. M.; Borchardt, M. T.; Den Hartog, D. J.; Falkowski, A. F.; Morton, L. A.; Thomas, M. A.

2016-11-01

The Thomson scattering diagnostic on the Madison Symmetric Torus (MST) records excessive levels of stray Nd:YAG laser light. Stray light saturates the 1064 nm spectral channel in all polychromators, which prevents absolute electron density measurements via Rayleigh scattering calibration. Furthermore, stray light contaminates adjacent spectral channels for r/a ≥ 0.75, which renders the diagnostic unable to make electron temperature measurements at these radii. In situ measurements of stray light levels during a vacuum vessel vent are used to identify stray light sources and strategies for reduction of stray light levels. Numerical modeling using Zemax OpticStudio supports these measurements. The model of the vacuum vessel and diagnostic includes synthetic collection optics to enable direct comparison of measured and simulated stray light levels. Modeling produces qualitatively similar stray light distributions to MST measurements, and quantifies the mitigation effects of stray light mitigation strategies prior to implementation.

Specific feature of magnetooptical images of stray fields of magnets of various geometrical shapes

NASA Astrophysics Data System (ADS)

Ivanov, V. E.; Koveshnikov, A. V.; Andreev, S. V.

2017-08-01

Specific features of magnetooptical images (MOIs) of stray fields near the faces of prismatic hard magnetic elements have been studied. Attention has primarily been focused on MOIs of fields near faces oriented perpendicular to the magnetic moment of hard magnetic elements. With regard to the polar sensitivity, MOIs have practically uniform brightness and geometrically they coincide with the figures of the bases of the elements. With regard to longitudinal sensitivity, MOIs consist of several sectors, the number of which is determined by the number of angles of the image. Each angle is divided by the bisectrix into two sectors of different brightnesses; therefore, the MOI of a triangular magnet consists of three sectors. A rectangle consists of four sectors separated by the bisectrices of the interior angles. In all types of figures, these lines converge at the center of the figure and form a singular point of the source or sink type.

Identification and mitigation of stray laser light in the Thomson scattering system on the Madison Symmetric Torus (MST)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobson, C. M., E-mail: cjacobson@wisc.edu; Borchardt, M. T.; Den Hartog, D. J.

The Thomson scattering diagnostic on the Madison Symmetric Torus (MST) records excessive levels of stray Nd:YAG laser light. Stray light saturates the 1064 nm spectral channel in all polychromators, which prevents absolute electron density measurements via Rayleigh scattering calibration. Furthermore, stray light contaminates adjacent spectral channels for r/a ≥ 0.75, which renders the diagnostic unable to make electron temperature measurements at these radii. In situ measurements of stray light levels during a vacuum vessel vent are used to identify stray light sources and strategies for reduction of stray light levels. Numerical modeling using Zemax OpticStudio supports these measurements. The modelmore » of the vacuum vessel and diagnostic includes synthetic collection optics to enable direct comparison of measured and simulated stray light levels. Modeling produces qualitatively similar stray light distributions to MST measurements, and quantifies the mitigation effects of stray light mitigation strategies prior to implementation.« less

SeaWiFS technical report series. Volume 31: Stray light in the SeaWiFS radiometer

NASA Technical Reports Server (NTRS)

Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Acker, James G. (Editor); Barnes, Robert A.; Holmes, Alan W.; Esaias, Wayne E.

1995-01-01

Some of the measurements from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) will not be useful as ocean measurements. For the ocean data set, there are procedures in place to mask the SeaWiFS measurements of clouds and ice. Land measurements will also be masked using a geographic technique based on each measurment's latitude and longitude. Each of these masks involves a source of light much brighter than the ocean. Because of stray light in the SeaWiFS radiometer, light from these bright sources can contaminate ocean measurements located a variable number of pixels away from a bright source. In this document, the sources of stray light in the sensor are examined, and a method is developed for masking measurements near bright targets for stray light effects. In addition, a procedure is proposed for reducing the effects of stray light in the flight data from SeaWiFS. This correction can also reduce the number of pixels masked for stray light. Without these corrections, local area scenes must be masked 10 pixels before and after bright targets in the along-scan direction. The addition of these corrections reduces the along-scan masks to four pixels before and after bright sources. In the along-track direction, the flight data are not corrected, and are masked two pixels before and after. Laboratory measurements have shown that stray light within the instrument changes in a direct ratio to the intensity of the bright source. The measurements have also shown that none of the bands show peculiarities in their stray light response. In other words, the instrument's response is uniform from band to band. The along-scan correction is based on each band's response to a 1 pixel wide bright sources. Since these results are based solely on preflight laboratory measurements, their successful implementation requires compliance with two additional criteria. First, since SeaWiFS has a large data volume, the correction and masking procedures must be such that they can be converted into computationally fast algorithms. Second, they must be shown to operate properly on flight data. The laboratory results, and the corrections and masking procedures that derive from them, should be considered as zeroeth order estimates of the effects that will be found on orbit.

Nanocluster building blocks of artificial square spin ice: Stray-field studies of thermal dynamics

NASA Astrophysics Data System (ADS)

Pohlit, Merlin; Porrati, Fabrizio; Huth, Michael; Ohno, Yuzo; Ohno, Hideo; Müller, Jens

2015-05-01

We present measurements of the thermal dynamics of a Co-based single building block of an artificial square spin ice fabricated by focused electron-beam-induced deposition. We employ micro-Hall magnetometry, an ultra-sensitive tool to study the stray field emanating from magnetic nanostructures, as a new technique to access the dynamical properties during the magnetization reversal of the spin-ice nanocluster. The obtained hysteresis loop exhibits distinct steps, displaying a reduction of their "coercive field" with increasing temperature. Therefore, thermally unstable states could be repetitively prepared by relatively simple temperature and field protocols allowing one to investigate the statistics of their switching behavior within experimentally accessible timescales. For a selected switching event, we find a strong reduction of the so-prepared states' "survival time" with increasing temperature and magnetic field. Besides the possibility to control the lifetime of selected switching events at will, we find evidence for a more complex behavior caused by the special spin ice arrangement of the macrospins, i.e., that the magnetic reversal statistically follows distinct "paths" most likely driven by thermal perturbation.

Comparison of the performance of different instruments in the stray neutron field around the CERN Proton Synchrotron.

PubMed

Aza, Eleni; Caresana, Marco; Cassell, Christopher; Colombo, Valeria; Damjanovic, Sanja; Gilardoni, Simone; Manessi, Giacomo Paolo; Pangallo, Michel; Perrin, Daniel; Silari, Marco

2014-10-01

This paper discusses an intercomparison campaign carried out in several locations around the CERN Proton Synchrotron. The locations were selected in order to perform the measurements in different stray field conditions. Various neutron detectors were employed: ionisation chambers, conventional and extended range rem counters, both commercial and prototype ones, including a novel instrument called LUPIN, specifically conceived to work in pulsed fields. The attention was focused on the potential differences in the instrument readings due to dead-time losses that are expected to affect most commercial units. The results show that the ionisation chambers and LUPIN agree well with the expected H*(10) values, as derived from FLUKA simulations, showing no relevant underestimations even in strongly pulsed fields. On the contrary, the dead-time losses of the other rem counters induced an underestimation in pulsed fields that was more important for instruments characterised by a higher dead time. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Contemporary Proton Therapy Systems Adequately Protect Patients from Exposure to Stray Radiation

NASA Astrophysics Data System (ADS)

Newhauser, Wayne D.; Fontenot, Jonas D.; Taddei, Phillip J.; Mirkovic, Dragan; Giebeler, Annelise; Zhang, Rui; Mahajan, Anita; Kornguth, David; Stovall, Marilyn; Yepes, Pablo; Woo, Shiao; Mohan, Radhe

2009-03-01

Proton beam therapy has provided safe and effective treatments for a variety of adult cancers. In recent years, there has been increasing interest in utilizing proton therapy for pediatric cancers because it allows better sparing of healthy tissues. Minimizing exposures of normal tissues is especially important in children because they are highly susceptible to consequential late effects, including the development of a radiogenic second cancer, which may occur years or even decades after treatment of the first cancer. While the dosimetric advantage of therapeutic proton beams is well understood, relatively little attention has been paid to the whole-body exposure to stray neutron radiation that is inherent in proton therapy. In this report, we review the physical processes that lead to neutron exposures, discuss the potential for mitigating these exposures using advanced proton beam delivery systems, and present a comparative analysis of predicted second cancer incidence following various external beam therapies. In addition, we discuss uncertainties in the relative biological effectiveness of neutrons for carcinogenesis and the impact that these uncertainties have on second-cancer risk predictions for survivors of adult and childhood cancer who receive proton therapy.

GASS: the Parkes Galactic all-sky survey. II. Stray-radiation correction and second data release

NASA Astrophysics Data System (ADS)

Kalberla, P. M. W.; McClure-Griffiths, N. M.; Pisano, D. J.; Calabretta, M. R.; Ford, H. Alyson; Lockman, F. J.; Staveley-Smith, L.; Kerp, J.; Winkel, B.; Murphy, T.; Newton-McGee, K.

2010-10-01

Context. The Parkes Galactic all-sky survey (GASS) is a survey of Galactic atomic hydrogen (H i) emission in the southern sky observed with the Parkes 64-m Radio Telescope. The first data release was published by McClure-Griffiths et al. (2009). Aims: We remove instrumental effects that affect the GASS and present the second data release. Methods: We calculate the stray-radiation by convolving the all-sky response of the Parkes antenna with the brightness temperature distribution from the Leiden/Argentine/Bonn (LAB) all sky 21-cm line survey, with major contributions from the 30-m dish of the Instituto Argentino de Radioastronomía (IAR) in the southern sky. Remaining instrumental baselines are corrected using the LAB data for a first guess of emission-free baseline regions. Radio frequency interference is removed by median filtering. Results: After applying these corrections to the GASS we find an excellent agreement with the Leiden/Argentine/Bonn (LAB) survey. The GASS is the highest spatial resolution, most sensitive, and is currently the most accurate H i survey of the Galactic H i emission in the southern sky. We provide a web interface for generation and download of FITS cubes.

Scaled-model guidelines for formation-flying solar coronagraph missions.

PubMed

Landini, Federico; Romoli, Marco; Baccani, Cristian; Focardi, Mauro; Pancrazzi, Maurizio; Galano, Damien; Kirschner, Volker

2016-02-15

Stray light suppression is the main concern in designing a solar coronagraph. The main contribution to the stray light for an externally occulted space-borne solar coronagraph is the light diffracted by the occulter and scattered by the optics. It is mandatory to carefully evaluate the diffraction generated by an external occulter and the impact that it has on the stray light signal on the focal plane. The scientific need for observations to cover a large portion of the heliosphere with an inner field of view as close as possible to the photospheric limb supports the ambition of launching formation-flying giant solar coronagraphs. Their dimension prevents the possibility of replicating the flight geometry in a clean laboratory environment, and the strong need for a scaled model is thus envisaged. The problem of scaling a coronagraph has already been faced for exoplanets, for a single point source on axis at infinity. We face the problem here by adopting an original approach and by introducing the scaling of the solar disk as an extended source.

Stray-light suppression in a reflecting white-light coronagraph

NASA Technical Reports Server (NTRS)

Romoli, Marco; Weiser, Heinz; Gardner, Larry D.; Kohl, John L.

1993-01-01

An analysis of stray-light suppression in the white-light channel of the Ultraviolet Coronagraph Spectrometer experiment for the Solar and Heliospheric Observatory is reported. The white-light channel consists of a reflecting telescope with external and internal occultation and a polarimeter section. Laboratory tests and analytical methods are used to perform the analysis. The various stray-light contributions are classified in two main categories: the contribution from sunlight that passes directly through the entrance aperture and the contribution of sunlight that is diffracted by the edges of the entrance aperture. Values of the stray-light contributions from various sources and the total stray-light level for observations at heliocentric heights from 1.4 to 5 solar radii are derived. Anticipated signal-to-stray-light ratios are presented together with the effective stray-light rejection by the polarimeter, demonstrating the efficacy of the stray-light suppression design.

User's manual for University of Arizona APART program (Analysis Program - Arizona Radiation Trace)

NASA Technical Reports Server (NTRS)

Breault, R. P.

1975-01-01

A description and operating instructions for the Analysis Program Arizona Radiation Trace (APART) are given. This is a computer program that is able to efficiently and accurately predict the off-axis rejection characteristics of unwanted stray radiation for complex rotationally symmetric optical systems. The program first determines the critical objects or areas that scatter radiation to the image plane either directly or through imaging elements: this provides the opportunity to modify, if necessary, the design so that the number of critical areas seen by the image plane is reduced or the radiation to these critical areas is minimized. Next, the power distribution reaching the image plane and a sectional power map of all internal surfaces are computed. Angular information is also provided that relates the angle by which the radiation came into a surface to the angle by which the radiation is scattered out of the surface.

Multi-objective inverse design of sub-wavelength optical focusing structures for heat assisted magnetic recording

NASA Astrophysics Data System (ADS)

Bhargava, Samarth; Yablonovitch, Eli

2014-09-01

We report using Inverse Electromagnetic Design to computationally optimize the geometric shapes of metallic optical antennas or near-field transducers (NFTs) and dielectric waveguide structures that comprise a sub-wavelength optical focusing system for practical use in Heat Assisted Magnetic Recording (HAMR). This magnetic data-recording scheme relies on focusing optical energy to locally heat the area of a single bit, several hundred square nanometers on a hard disk, to the Curie temperature of the magnetic storage layer. There are three specifications of the optical system that must be met to enable HAMR as a commercial technology. First, to heat the media at scan rates upward of 10 m/s, ~1mW of light (<1% of typical laser diode output power) must be focused to a 30nm×30nm spot on the media. Second, the required lifetime of many years necessitates that the nano-scale NFT must not over-heat from optical absorption. Third, to avoid undesired erasing or interference of adjacent tracks on the media, there must be minimal stray optical radiation away from the hotspot on the hard disk. One cannot design the light delivery system by tackling each of these challenges independently, because they are governed by coupled electromagnetic phenomena. Instead, we propose multiobjective optimization using Inverse Electromagnetic Design in conjunction with a commercial 3D FDTD Maxwell's equations solver. We computationally generated designs of a metallic NFT and a high-index waveguide grating that meet the HAMR specifications simultaneously. Compared to a mock industry design, our proposed design has a similar optical coupling efficiency, ~3x improved suppression of stray optical radiation, and a 60% (280°C) reduction in NFT temperature rise. We also distributed the Inverse Electromagnetic Design software online so that industry partners can use it as a repeatable design process.

Non-Destructive Monitoring of Charge-Discharge Cycles on Lithium Ion Batteries using 7Li Stray-Field Imaging

PubMed Central

Tang, Joel A.; Dugar, Sneha; Zhong, Guiming; Dalal, Naresh S.; Zheng, Jim P.; Yang, Yong; Fu, Riqiang

2013-01-01

Magnetic resonance imaging provides a noninvasive method for in situ monitoring of electrochemical processes involved in charge/discharge cycling of batteries. Determining how the electrochemical processes become irreversible, ultimately resulting in degraded battery performance, will aid in developing new battery materials and designing better batteries. Here we introduce the use of an alternative in situ diagnostic tool to monitor the electrochemical processes. Utilizing a very large field-gradient in the fringe field of a magnet, stray-field-imaging (STRAFI) technique significantly improves the image resolution. These STRAFI images enable the real time monitoring of the electrodes at a micron level. It is demonstrated by two prototype half-cells, graphite∥Li and LiFePO4∥Li, that the high-resolution 7Li STRAFI profiles allow one to visualize in situ Li-ions transfer between the electrodes during charge/discharge cyclings as well as the formation and changes of irreversible microstructures of the Li components, and particularly reveal a non-uniform Li-ion distribution in the graphite. PMID:24005580

Rabies Vaccination Targets for Stray Dog Populations

PubMed Central

Leung, Tiffany; Davis, Stephen A.

2017-01-01

The role of stray dogs in the persistence of domestic dog rabies, and whether removal of such dogs is beneficial, remains contentious issues for control programs seeking to eliminate rabies. While a community might reach the WHO vaccination target of 70% for dogs that can be handled, the stray or neighborhood dogs that are too wary of humans to be held are a more problematic population to vaccinate. Here, we present a method to estimate vaccination targets for stray dogs when the dog population is made up of stray, free-roaming, and confined dogs, where the latter two types are considered to have an identifiable owner. The control effort required for stray dogs is determined by the type-reproduction number, T1, the number of stray dogs infected by one rabid stray dog either directly or via any chain of infection involving owned dogs. Like the basic reproduction number R0 for single host populations, T1 determines the vaccination effort required to control the spread of disease when control is targeted at one host type, and there is a mix of host types. The application of T1 to rabies in mixed populations of stray and owned dogs is novel. We show that the outcome is sensitive to the vaccination coverage in the owned dog population, such that if vaccination rates of owned dogs were too low then no control effort targeting stray dogs is able to control or eliminate rabies. The required vaccination level also depends on the composition of the dog population, where a high proportion of either stray or free-roaming dogs implies unrealistically high vaccination levels are required to prevent rabies. We find that the required control effort is less sensitive to continuous culling that increases the death rate of stray dogs than to changes in the carrying capacity of the stray dog population. PMID:28451589

Eliminating Unwanted Far-Field Excitation in Objective-Type TIRF. Part II. Combined Evanescent-Wave Excitation and Supercritical-Angle Fluorescence Detection Improves Optical Sectioning

PubMed Central

Brunstein, Maia; Hérault, Karine; Oheim, Martin

2014-01-01

Azimuthal beam scanning makes evanescent-wave (EW) excitation isotropic, thereby producing total internal reflection fluorescence (TIRF) images that are evenly lit. However, beam spinning does not fundamentally address the problem of propagating excitation light that is contaminating objective-type TIRF. Far-field excitation depends more on the specific objective than on cell scattering. As a consequence, the excitation impurities in objective-type TIRF are only weakly affected by changes of azimuthal or polar beam angle. These are the main results of the first part of this study (Eliminating unwanted far-field excitation in objective-type TIRF. Pt.1. Identifying sources of nonevanescent excitation light). This second part focuses on exactly where up beam in the illumination system stray light is generated that gives rise to nonevanescent components in TIRF. Using dark-field imaging of scattered excitation light we pinpoint the objective, intermediate lenses and, particularly, the beam scanner as the major sources of stray excitation. We study how adhesion-molecule coating and astrocytes or BON cells grown on the coverslip surface modify the dark-field signal. On flat and weakly scattering cells, most background comes from stray reflections produced far from the sample plane, in the beam scanner and the objective lens. On thick, optically dense cells roughly half of the scatter is generated by the sample itself. We finally show that combining objective-type EW excitation with supercritical-angle fluorescence (SAF) detection efficiently rejects the fluorescence originating from deeper sample regions. We demonstrate that SAF improves the surface selectivity of TIRF, even at shallow penetration depths. The coplanar microscopy scheme presented here merges the benefits of beam spinning EW excitation and SAF detection and provides the conditions for quantitative wide-field imaging of fluorophore dynamics at or near the plasma membrane. PMID:24606929

Baseline design and requirements for the LSST rotating enclosure (dome)

NASA Astrophysics Data System (ADS)

Neill, D. R.; DeVries, J.; Hileman, E.; Sebag, J.; Gressler, W.; Wiecha, O.; Andrew, J.; Schoening, W.

2014-07-01

The Large Synoptic Survey Telescope (LSST) is a large (8.4 meter) wide-field (3.5 degree) survey telescope, which will be located on the Cerro Pachón summit in Chile. As a result of the wide field of view, its optical system is unusually susceptible to stray light; consequently besides protecting the telescope from the environment the rotating enclosure (Dome) also provides indispensible light baffling. All dome vents are covered with light baffles which simultaneously provide both essential dome flushing and stray light attenuation. The wind screen also (and primarily) functions as a light screen providing only a minimum clear aperture. Since the dome must operate continuously, and the drives produce significant heat, they are located on the fixed lower enclosure to facilitate glycol water cooling. To accommodate day time thermal control, a duct system channels cooling air provided by the facility when the dome is in its parked position.

Prevalence and Characterization of Escherichia coli and Salmonella Strains Isolated from Stray Dog and Coyote Feces in a Major Leafy Greens Production Region at the United States-Mexico Border

PubMed Central

Jay-Russell, Michele T.; Hake, Alexis F.; Bengson, Yingjia; Thiptara, Anyarat; Nguyen, Tran

2014-01-01

In 2010, Romaine lettuce grown in southern Arizona was implicated in a multi-state outbreak of Escherichia coli O145:H28 infections. This was the first known Shiga toxin-producing E. coli (STEC) outbreak traced to the southwest desert leafy green vegetable production region along the United States-Mexico border. Limited information exists on sources of STEC and other enteric zoonotic pathogens in domestic and wild animals in this region. According to local vegetable growers, unleashed or stray domestic dogs and free-roaming coyotes are a significant problem due to intrusions into their crop fields. During the 2010–2011 leafy greens growing season, we conducted a prevalence survey of STEC and Salmonella presence in stray dog and coyote feces. Fresh fecal samples from impounded dogs and coyotes from lands near produce fields were collected and cultured using extended enrichment and serogroup-specific immunomagnetic separation (IMS) followed by serotyping, pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing. A total of 461 fecal samples were analyzed including 358 domestic dog and 103 coyote fecals. STEC was not detected, but atypical enteropathogenic E. coli (aEPEC) strains comprising 14 different serotypes were isolated from 13 (3.6%) dog and 5 (4.9%) coyote samples. Salmonella was cultured from 33 (9.2%) dog and 33 (32%) coyote samples comprising 29 serovars with 58% from dogs belonging to Senftenberg or Typhimurium. PFGE analysis revealed 17 aEPEC and 27 Salmonella distinct pulsotypes. Four (22.2%) of 18 aEPEC and 4 (6.1%) of 66 Salmonella isolates were resistant to two or more antibiotic classes. Our findings suggest that stray dogs and coyotes in the desert southwest may not be significant sources of STEC, but are potential reservoirs of other pathogenic E. coli and Salmonella. These results underscore the importance of good agriculture practices relating to mitigation of microbial risks from animal fecal deposits in the produce production area. PMID:25412333

System implications of aperture-shade design for the SIRTF Observatory

NASA Technical Reports Server (NTRS)

Lee, J. H.; Brooks, W. F.; Maa, S.

1987-01-01

The 1-m-aperture Space Infrared Telescope Facility (SIRTF) will operate with a sensitivity limited only by the zodiacal background. This sensitivity requirement places severe restrictions on the amount of stray light which can reach the focal plane from off-axis sources such as the sun or earth limb. In addition, radiation from these sources can degrade the lifetime of the telescope and instrument cryogenic system which is now planned for two years before the first servicing. Since the aperture of the telescope represents a break in the telescope insulation system and is effectively the first element in the optical train, the aperture shade is a key system component. The mass, length, and temperature of the shade should be minimized to reduce system cost while maximizing the telescope lifetime and stray light performance. The independent geometric parameters that characterize an asymmetrical shade for a 600 km, 28 deg orbit were identified, and the system sensitivity to the three most important shade parameters were explored. Despite the higher heat loads compared to previously studied polar orbit missions, the analysis determined that passive radiators of a reasonable size are sufficient to meet the system requirements. An optimized design for the SIRTF mission, based on the sensitivity analysis, is proposed.

Stray light correction of array spectroradiometer measurement in ultraviolet

NASA Astrophysics Data System (ADS)

Wu, Zhifeng; Dai, Caihong; Wang, Yanfei; Li, Ling

2018-02-01

For most of the array spectroradiometer, stray light is significant in UV band. Stray light correction of a UV array spectroradiometer is investigated using optical filters. If a group of filters with continuous bandpass are chosen, stray light contribution due to all the bands can be obtained using a numerical algorithm. The array spectroradiometer with the stray light corrected is used to measure the spectral irradiance of several UV lamps. The measurement results are compared to a double monochromator spectroradiometer. When xenon lamp is the array spectroradiometer calibration lamp, after stray light correction, the difference can be improved from nearly 10% to 2.0% in UVC band. When tungsten lamp is the calibration lamp, the difference can be improved from around 90% to less than 20%.

Novel ray tracing method for stray light suppression from ocean remote sensing measurements.

PubMed

Oh, Eunsong; Hong, Jinsuk; Kim, Sug-Whan; Park, Young-Je; Cho, Seong-Ick

2016-05-16

We developed a new integrated ray tracing (IRT) technique to analyze the stray light effect in remotely sensed images. Images acquired with the Geostationary Ocean Color Imager show a radiance level discrepancy at the slot boundary, which is suspected to be a stray light effect. To determine its cause, we developed and adjusted a novel in-orbit stray light analysis method, which consists of three simulated phases (source, target, and instrument). Each phase simulation was performed in a way that used ray information generated from the Sun and reaching the instrument detector plane efficiently. This simulation scheme enabled the construction of the real environment from the remote sensing data, with a focus on realistic phenomena. In the results, even in a cloud-free environment, a background stray light pattern was identified at the bottom of each slot. Variations in the stray light effect and its pattern according to bright target movement were simulated, with a maximum stray light ratio of 8.5841% in band 2 images. To verify the proposed method and simulation results, we compared the results with the real acquired remotely sensed image. In addition, after correcting for abnormal phenomena in specific cases, we confirmed that the stray light ratio decreased from 2.38% to 1.02% in a band 6 case, and from 1.09% to 0.35% in a band 8 case. IRT-based stray light analysis enabled clear determination of the stray light path and candidates in in-orbit circumstances, and the correction process aided recovery of the radiometric discrepancy.

Characterizing the Noble Gas Isotopic Composition of the Barnett Shale and Strawn Group and Constraining the Source of Stray Gas in the Trinity Aquifer, North-Central Texas.

PubMed

Wen, Tao; Castro, M Clara; Nicot, Jean-Philippe; Hall, Chris M; Pinti, Daniele L; Mickler, Patrick; Darvari, Roxana; Larson, Toti

2017-06-06

This study presents the complete set of stable noble gases for Barnett Shale and Strawn Group production gas together with stray flowing gas in the Trinity Aquifer, Texas. It places new constraints on the source of this stray gas and further shows that Barnett and Strawn gas have distinct crustal and atmospheric noble gas signatures, allowing clear identification of these two sources. Like stray gas, Strawn gas is significantly more enriched in crustal 4 He*, 21 Ne*, and 40 Ar* than Barnett gas. The similarity of Strawn and stray gas crustal noble gas signatures suggests that the Strawn is the source of stray gas in the Trinity Aquifer. Atmospheric 22 Ne/ 36 Ar ratios of stray gas mimic also that of Strawn, further reinforcing the notion that the source of stray gas in this aquifer is the Strawn. While noble gas signatures of Strawn and stray gas are consistent with a single-stage water degassing model, a two-stage oil modified groundwater exsolution fractionation model is required to explain the light atmospheric noble gas signature of Barnett Shale production gas. These distinct Strawn and Barnett noble gas signatures are likely the reflection of distinct evolution histories with Strawn gas being possibly older than that of Barnett Shale.

Barnett Shale or Strawn Group: Identifying the Source of Stray Gas through Noble Gases in the Trinity Aquifer, North-Central Texas

NASA Astrophysics Data System (ADS)

Wen, T.; Castro, M. C.; Nicot, J. P.; Hall, C. M.; Pinti, D. L.; Mickler, P. J.; Darvari, R.; Larson, T. E.

2017-12-01

The complete set of stable noble gases (He, Ne, Ar, Kr, Xe) is presented for Barnett Shale and Strawn Group production gas together with that of stray flowing gas present in the Trinity Aquifer, Texas. It places new constraints on the source of this stray gas and further shows that Barnett and Strawn gas have distinct crustal and atmospheric noble gas signatures, allowing clear identification of these two sources. Like Trinity Aquifer stray gas, Strawn gas is significantly more enriched in crustal 4He*, 21Ne*, and 40Ar* than Barnett gas. The similarity of Strawn and stray gas crustal noble gas signatures suggests that the Strawn is the source of stray gas in the Trinity Aquifer. Atmospheric 22Ne/36Ar ratios of stray gas mimic also that of Strawn, further reinforcing the notion that the source of stray gas in this aquifer is the Strawn. While noble gas signatures of Strawn and stray gas are consistent with a single-stage water degassing model, a two-stage oil modified groundwater exsolution fractionation model is required to explain the light atmospheric noble gas signature of Barnett Shale production gas. These distinct Strawn and Barnett noble gas signatures are likely the reflection of distinct evolution histories with Strawn gas being possibly older than that of Barnett Shale.

Magneto-optical visualization of three spatial components of inhomogeneous stray fields

NASA Astrophysics Data System (ADS)

Ivanov, V. E.

2012-08-01

The article deals with the physical principles of magneto-optical visualization (MO) of three spatial components of inhomogeneous stray fields with the help of FeCo metal indicator films in the longitudinal Kerr effect geometry. The inhomogeneous field is created by permanent magnets. Both p- and s-polarization light is used for obtaining MO images with their subsequent summing, subtracting and digitizing. As a result, the MO images and corresponding intensity coordinate dependences reflecting the distributions of the horizontal and vertical magnetization components in pure form have been obtained. Modeling of both the magnetization distribution in the indicator film and the corresponding MO images shows that corresponding to polar sensitivity the intensity is proportional to the normal field component, which permits normal field component mapping. Corresponding to longitudinal sensitivity, the intensity of the MO images reflects the angular distribution of the planar field component. MO images have singular points in which the planar component is zero and their movement under an externally homogeneous planar field permits obtaining of additional information on the two planar components of the field under study. The intensity distribution character in the vicinity of sources and sinks (singular points) remains the same under different orientations of the light incidence plane. The change of incident plane orientation by π/2 alters the distribution pattern in the vicinity of the saddle points.

A new dump system design for stray light reduction of Thomson scattering diagnostic system on EAST.

PubMed

Xiao, Shumei; Zang, Qing; Han, Xiaofeng; Wang, Tengfei; Yu, Jin; Zhao, Junyu

2016-07-01

Thomson scattering (TS) diagnostic is an important diagnostic for measuring electron temperature and density during plasma discharge. However, the measurement of Thomson scattering signal is disturbed by the stray light easily. The stray light sources in the Experimental Advanced Superconducting Tokamak (EAST) TS diagnostic system were analyzed by a simulation model of the diagnostic system, and simulation results show that the dump system is the primary stray light source. Based on the optics theory and the simulation analysis, a novel dump system including an improved beam trap was proposed and installed. The measurement results indicate that the new dump system can reduce more than 60% of the stray light for the diagnostic system, and the influence of stray light on the error of measured density decreases.

Nanocluster building blocks of artificial square spin ice: Stray-field studies of thermal dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pohlit, Merlin, E-mail: pohlit@physik.uni-frankfurt.de; Porrati, Fabrizio; Huth, Michael

We present measurements of the thermal dynamics of a Co-based single building block of an artificial square spin ice fabricated by focused electron-beam-induced deposition. We employ micro-Hall magnetometry, an ultra-sensitive tool to study the stray field emanating from magnetic nanostructures, as a new technique to access the dynamical properties during the magnetization reversal of the spin-ice nanocluster. The obtained hysteresis loop exhibits distinct steps, displaying a reduction of their “coercive field” with increasing temperature. Therefore, thermally unstable states could be repetitively prepared by relatively simple temperature and field protocols allowing one to investigate the statistics of their switching behavior withinmore » experimentally accessible timescales. For a selected switching event, we find a strong reduction of the so-prepared states' “survival time” with increasing temperature and magnetic field. Besides the possibility to control the lifetime of selected switching events at will, we find evidence for a more complex behavior caused by the special spin ice arrangement of the macrospins, i.e., that the magnetic reversal statistically follows distinct “paths” most likely driven by thermal perturbation.« less

[UV-radiation--sources, wavelength, environment].

PubMed

Hölzle, Erhard; Hönigsmann, Herbert

2005-09-01

The UV-radiation in our environment is part of the electromagnetic radiation, which emanates from the sun. It is designated as optical radiation and reaches from 290-4,000 nm on the earth's surface. According to international definitions UV irradiation is divided into short-wave UVC (200-280 nm), medium-wave UVB (280-320 nm), and long-wave UVA (320-400 nm). Solar radiation which reaches the surface of the globe at a defined geographical site and a defined time point is called global radiation. It is modified quantitatively and qualitatively while penetrating the atmosphere. Besides atmospheric conditions, like ozone layer and air pollution, geographic latitude, elevation, time of the season, time of the day, cloudiness and the influence of indirect radiation resulting from stray effects in the atmosphere and reflection from the underground play a role in modifying global radiation, which finally represents the biologically effective radiation. The radiation's distribution on the body surface varies according to sun angle and body posture. The cumulative UV exposure is mainly influenced by outdoor profession and recreational activities. The use of sun beds and phototherapeutic measures additionally may contribute to the cumulative UV dose.

Room-temperature antiferromagnetic memory resistor.

PubMed

Marti, X; Fina, I; Frontera, C; Liu, Jian; Wadley, P; He, Q; Paull, R J; Clarkson, J D; Kudrnovský, J; Turek, I; Kuneš, J; Yi, D; Chu, J-H; Nelson, C T; You, L; Arenholz, E; Salahuddin, S; Fontcuberta, J; Jungwirth, T; Ramesh, R

2014-04-01

The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.

A new dump system design for stray light reduction of Thomson scattering diagnostic system on EAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Shumei; Zang, Qing, E-mail: zangq@ipp.ac.cn; Han, Xiaofeng

Thomson scattering (TS) diagnostic is an important diagnostic for measuring electron temperature and density during plasma discharge. However, the measurement of Thomson scattering signal is disturbed by the stray light easily. The stray light sources in the Experimental Advanced Superconducting Tokamak (EAST) TS diagnostic system were analyzed by a simulation model of the diagnostic system, and simulation results show that the dump system is the primary stray light source. Based on the optics theory and the simulation analysis, a novel dump system including an improved beam trap was proposed and installed. The measurement results indicate that the new dump systemmore » can reduce more than 60% of the stray light for the diagnostic system, and the influence of stray light on the error of measured density decreases.« less

METIS: the visible and UV coronagraph for solar orbiter

NASA Astrophysics Data System (ADS)

Romoli, M.; Landini, F.; Antonucci, E.; Andretta, V.; Berlicki, A.; Fineschi, S.; Moses, J. D.; Naletto, G.; Nicolosi, P.; Nicolini, G.; Spadaro, D.; Teriaca, L.; Baccani, C.; Focardi, M.; Pancrazzi, M.; Pucci, S.; Abbo, L.; Bemporad, A.; Capobianco, G.; Massone, G.; Telloni, D.; Magli, E.; Da Deppo, V.; Frassetto, F.; Pelizzo, M. G.; Poletto, L.; Uslenghi, M.; Vives, S.; Malvezzi, M.

2017-11-01

METIS coronagraph is designed to observe the solar corona with an annular field of view from 1.5 to 2.9 degrees in the visible broadband (580-640 nm) and in the UV HI Lyman-alpha, during the Sun close approaching and high latitude tilting orbit of Solar Orbiter. The big challenge for a coronagraph is the stray light rejection. In this paper after a description of the present METIS optical design, the stray light rejection design is presented in detail together with METIS off-pointing strategies throughout the mission. Data shown in this paper derive from the optimization of the optical design performed with Zemax ray tracing and from laboratory breadboards of the occultation system and of the polarimeter.

Magnetic field generator

DOEpatents

Krienin, Frank

1990-01-01

A magnetic field generating device provides a useful magnetic field within a specific retgion, while keeping nearby surrounding regions virtually field free. By placing an appropriate current density along a flux line of the source, the stray field effects of the generator may be contained. One current carrying structure may support a truncated cosine distribution, and it may be surrounded by a current structure which follows a flux line that would occur in a full coaxial double cosine distribution. Strong magnetic fields may be generated and contained using superconducting cables to approximate required current surfaces.

Magnetic stray-field studies of a single Cobalt nanoelement as a component of the building blocks of artificial square spin ice

NASA Astrophysics Data System (ADS)

Pohlit, Merlin; Porrati, Fabrizio; Huth, Michael; Ohno, Yuzo; Ohno, Hideo; Müller, Jens

2016-02-01

We use Focused Electron Beam Deposition (FEBID) to directly write Cobalt magnetic nanoelements onto a micro-Hall magnetometer, which allows for high-sensitivity measurements of the magnetic stray field emanating from the samples. In a previous study [M. Pohlit et al., J. Appl. Phys. 117 (2015) 17C746] [21] we investigated thermal dynamics of an individual building block (nanocluster) of artificial square spin ice. In this work, we compare the results of this structure with interacting elements to the switching of a single nanoisland. By analyzing the survival function of the repeatedly prepared state in a given temperature range, we find thermally activated switching dynamics. A detailed analysis of the hysteresis loop reveals a metastable microstate preceding the overall magnetization reversal of the single nanoelement, also found in micromagnetic simulations. Such internal degrees of freedom may need to be considered, when analyzing the thermal dynamics of larger spin ice configurations on different lattice types.

Broadband ultraviolet reflectance filters for space applications.

NASA Technical Reports Server (NTRS)

Osantowski, J. F.; Toft, A. R.

1973-01-01

It is shown that a simple metal-dielectric-metal filter for broadband ultraviolet (BUV) reflectance control can provide a stable and effective means for reducing stray visible radiation in UV reflective optical systems. The application of such a filter in a BUV instrument resulted in a reduction of scattered visible light by at least an order of magnitude. The instrument has been in orbit for 2.5 year without loss of sensitivity or an increase in scattered light background.-

Stray light analysis for the Thomson scattering diagnostic of the ETE Tokamak.

PubMed

Berni, L A; Albuquerque, B F C

2010-12-01

Thomson scattering is a well-established diagnostic for measuring local electron temperature and density in fusion plasma, but this technique is particularly difficult to implement due to stray light that can easily mask the scattered signal from plasma. To mitigate this problem in the multipoint Thomson scattering system implemented at the ETE (Experimento Tokamak Esférico) a detailed stray light analysis was performed. The diagnostic system was simulated in ZEMAX software and scattering profiles of the mechanical parts were measured in the laboratory in order to have near realistic results. From simulation, it was possible to identify the main points that contribute to the stray signals and changes in the dump were implemented reducing the stray light signals up to 60 times.

Silicon drift detectors with on-chip electronics for x-ray spectroscopy.

PubMed

Fiorini, C; Longoni, A; Hartmann, R; Lechner, P; Strüder, L

1997-01-01

The silicon drift detector (SDD) is a semiconductor device based on high resistivity silicon fully depleted through junctions implanted on both sides of the semiconductor wafer. The electrons generated by the ionizing radiation are driven by means of a suitable electric field from the point of interaction toward a collecting anode of small capacitance, independent of the active area of the detector. A suitably designed front-end JFET has been directly integrated on the detector chip close to the anode region, in order to obtain a nearly ideal capacitive matching between detector and transistor and to minimize the stray capacitances of the connections. This feature allows it to reach high energy resolution also at high count rates and near room temperature. The present work describes the structure and the performance of SDDs specially designed for high resolution spectroscopy with soft x rays at high detection rate. Experimental results of SDDs used in spectroscopy applications are also reported.

Workplace Learning: Emerging Trends and New Perspectives

ERIC Educational Resources Information Center

Fenwick, Tara

2008-01-01

This chapter focuses on "learning processes" in the workplace from concepts emerging in the field of adult education, without straying into pedagogies and programs that can enhance learning. It discusses four topics on learning processes that seem to be particularly important for addressing key purposes and issues of workplace learning from an…

Effective shielding to measure beam current from an ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bayle, H., E-mail: bayle@bergoz.com; Delferrière, O.; Gobin, R.

To avoid saturation, beam current transformers must be shielded from solenoid, quad, and RFQ high stray fields. Good understanding of field distribution, shielding materials, and techniques is required. Space availability imposes compact shields along the beam pipe. This paper describes compact effective concatenated magnetic shields for IFMIF-EVEDA LIPAc LEBT and MEBT and for FAIR Proton Linac injector. They protect the ACCT Current Transformers beyond 37 mT radial external fields. Measurements made at Saclay on the SILHI source are presented.

Recent Upgrades and Extensions of the ASDEX Upgrade ECRH System

NASA Astrophysics Data System (ADS)

Wagner, Dietmar; Stober, Jörg; Leuterer, Fritz; Monaco, Francesco; Münich, Max; Schmid-Lorch, Dominik; Schütz, Harald; Zohm, Hartmut; Thumm, Manfred; Scherer, Theo; Meier, Andreas; Gantenbein, Gerd; Flamm, Jens; Kasparek, Walter; Höhnle, Hendrik; Lechte, Carsten; Litvak, Alexander G.; Denisov, Gregory G.; Chirkov, Alexey; Popov, Leonid G.; Nichiporenko, Vadim O.; Myasnikov, Vadim E.; Tai, Evgeny M.; Solyanova, Elena A.; Malygin, Sergey A.

2011-03-01

The multi-frequency Electron Cyclotron Heating (ECRH) system at the ASDEX Upgrade tokamak employs depressed collector gyrotrons, step-tunable in the range 105-140 GHz. The system is equipped with a fast steerable launcher allowing for remote steering of the ECRH RF beam during the plasma discharge. The gyrotrons and the mirrors are fully integrated in the discharge control system. The polarization can be controlled in a feed-forward mode. 3 Sniffer probes for millimeter wave stray radiation detection have been installed.

Halbach Effect at the Nanoscale from Chiral Spin Textures.

PubMed

Marioni, Miguel A; Penedo, Marcos; Baćani, Mirko; Schwenk, Johannes; Hug, Hans J

2018-04-11

Mallinson's idea that some spin textures in planar magnetic structures could produce an enhancement of the magnetic flux on one side of the plane at the expense of the other gave rise to permanent magnet configurations known as Halbach magnet arrays. Applications range from wiggler magnets in particle accelerators and free electron lasers to motors and magnetic levitation trains, but exploiting Halbach arrays in micro- or nanoscale spintronics devices requires solving the problem of fabrication and field metrology below a 100 μm size. In this work, we show that a Halbach configuration of moments can be obtained over areas as small as 1 μm × 1 μm in sputtered thin films with Néel-type domain walls of unique domain wall chirality, and we measure their stray field at a controlled probe-sample distance of 12.0 ± 0.5 nm. Because here chirality is determined by the interfacial Dyzaloshinkii-Moriya interaction, the field attenuation and amplification is an intrinsic property of this film, allowing for flexibility of design based on an appropriate definition of magnetic domains. Skyrmions (<100 nm wide) illustrate the smallest kind of such structures, for which our measurement of stray magnetic fields and mapping of the spin structure shows they funnel the field toward one specific side of the film given by the sign of the Dyzaloshinkii-Moriya interaction parameter D.

Stray light analysis for the Thomson scattering diagnostic of the ETE Tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berni, L. A.; Albuquerque, B. F. C.

2010-12-15

Thomson scattering is a well-established diagnostic for measuring local electron temperature and density in fusion plasma, but this technique is particularly difficult to implement due to stray light that can easily mask the scattered signal from plasma. To mitigate this problem in the multipoint Thomson scattering system implemented at the ETE (Experimento Tokamak Esferico) a detailed stray light analysis was performed. The diagnostic system was simulated in ZEMAX software and scattering profiles of the mechanical parts were measured in the laboratory in order to have near realistic results. From simulation, it was possible to identify the main points that contributemore » to the stray signals and changes in the dump were implemented reducing the stray light signals up to 60 times.« less

Extension of the ECRH operational space with O2 and X3 heating schemes to control tungsten accumulation in ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Höhnle, H.; Stober, J.; Herrmann, A.; Kasparek, W.; Leuterer, F.; Monaco, F.; Neu, R.; Schmid-Lorch, D.; Schütz, H.; Schweinzer, J.; Stroth, U.; Wagner, D.; Vorbrugg, S.; Wolfrum, E.; ASDEX Upgrade Team

2011-08-01

ASDEX Upgrade has been operated with tungsten-coated plasma-facing components for several years. H-mode operation with good confinement has been demonstrated. Nevertheless, purely neutral beam injection-heated H-modes with reduced gas puff, moderate heating power or/and increased triangularity tend to accumulate tungsten, followed by a radiative collapse. Under these conditions, central electron heating with electron cyclotron resonance heating (ECRH), usually in X2 polarization, changes the impurity transport in the plasma centre, reducing the central tungsten concentration and, in many cases, stabilizing the plasma. In order to extend the applicability of central ECRH to a wider range of magnetic field and plasma current additional ECRH schemes with reduced single-pass absorption have been implemented: X3 heating allows us to reduce the magnetic field by 30%, such that the first H-modes with an ITER-like value of the safety factor of q95 = 3 could be run in the tungsten-coated device. O2 heating increases the cutoff density by a factor of 2 allowing higher currents and triangularities to be addressed. For both schemes, scenarios have been developed to cope with the associated reduced absorption. In the case of central X3 heating, the X2 resonance lies close to the pedestal top at the high-field side of the plasma, serving as a beam dump. For O2, holographic mirrors have been developed which guarantee a second pass through the plasma centre. The beam position on these reflectors is controlled by fast thermocouples. Stray-radiation protection has been implemented using sniffer probes.

Using parentage analysis to estimate rates of straying and homing in Chinook salmon (Oncorhynchus tshawytscha).

PubMed

Ford, Michael J; Murdoch, Andrew; Hughes, Michael

2015-03-01

We used parentage analysis based on microsatellite genotypes to measure rates of homing and straying of Chinook salmon (Oncorhynchus tshawytscha) among five major spawning tributaries within the Wenatchee River, Washington. On the basis of analysis of 2248 natural-origin and 11594 hatchery-origin fish, we estimated that the rate of homing to natal tributaries by natural-origin fish ranged from 0% to 99% depending on the tributary. Hatchery-origin fish released in one of the five tributaries homed to that tributary at a far lower rate than the natural-origin fish (71% compared to 96%). For hatchery-released fish, stray rates based on parentage analysis were consistent with rates estimated using physical tag recoveries. Stray rates among major spawning tributaries were generally higher than stray rates of tagged fish to areas outside of the Wenatchee River watershed. Within the Wenatchee watershed, rates of straying by natural-origin fish were significantly affected by spawning tributary and by parental origin: progeny of naturally spawning hatchery-produced fish strayed at significantly higher rates than progeny whose parents were themselves of natural origin. Notably, none of the 170 offspring that were products of mating by two natural-origin fish strayed from their natal tributary. Indirect estimates of gene flow based on FST statistics were correlated with but higher than the estimates from the parentage data. Tributary-specific estimates of effective population size were also correlated with the number of spawners in each tributary. Published [2015]. This article is a U.S. Government work and is in the public domain in the USA.

Evaluation of Delamination of X80 Pipeline Steel Coating Under Alternating Stray Current Via Scanning Electrochemical Microscopy

NASA Astrophysics Data System (ADS)

Wang, Xinhua; Liu, Qiang; Chun, Yingchun; Li, Yingchao; Wang, Zuquan

2018-04-01

The delamination of epoxy coating on X80 pipeline steel was evaluated under various stray alternating current (AC) interferences (0-300 A/m2). Qualitative and quantitative analyses were carried out using scanning electrochemical microscopy (SECM), electrochemical impedance spectroscopy (EIS), and three-dimensional digital microscopy. The results show that the SECM current is directly proportional to the soaking time and applied current density. The variation in SECM current curve shape indicates the delamination distance of epoxy coatings at the defect area. The depths of corrosion pits at 50, 100, and 300 A/m2 stray currents were 140, 160, and 240 μm, respectively. The corrosion pits also became wider with increasing current densities. With increasing stray AC densities, both the coating delamination and pit depth became more severe at the same soaking time. The EIS results show that the change in impedance was not significant without stray current, whereas the impedance first decreased and then increased when stray current was applied. These results are consistent with the SECM measurements.

Unveiling aerosol-cloud interactions - Part 1: Cloud contamination in satellite products enhances the aerosol indirect forcing estimate

NASA Astrophysics Data System (ADS)

Christensen, Matthew W.; Neubauer, David; Poulsen, Caroline A.; Thomas, Gareth E.; McGarragh, Gregory R.; Povey, Adam C.; Proud, Simon R.; Grainger, Roy G.

2017-11-01

Increased concentrations of aerosol can enhance the albedo of warm low-level cloud. Accurately quantifying this relationship from space is challenging due in part to contamination of aerosol statistics near clouds. Aerosol retrievals near clouds can be influenced by stray cloud particles in areas assumed to be cloud-free, particle swelling by humidification, shadows and enhanced scattering into the aerosol field from (3-D radiative transfer) clouds. To screen for this contamination we have developed a new cloud-aerosol pairing algorithm (CAPA) to link cloud observations to the nearest aerosol retrieval within the satellite image. The distance between each aerosol retrieval and nearest cloud is also computed in CAPA. Results from two independent satellite imagers, the Advanced Along-Track Scanning Radiometer (AATSR) and Moderate Resolution Imaging Spectroradiometer (MODIS), show a marked reduction in the strength of the intrinsic aerosol indirect radiative forcing when selecting aerosol pairs that are located farther away from the clouds (-0.28±0.26 W m-2) compared to those including pairs that are within 15 km of the nearest cloud (-0.49±0.18 W m-2). The larger aerosol optical depths in closer proximity to cloud artificially enhance the relationship between aerosol-loading, cloud albedo, and cloud fraction. These results suggest that previous satellite-based radiative forcing estimates represented in key climate reports may be exaggerated due to the inclusion of retrieval artefacts in the aerosol located near clouds.

Characterisation of spectrophotometers used for spectral solar ultraviolet radiation measurements.

PubMed

Gröbner, J

2001-01-01

Spectrophotometers used for spectral measurements of the solar ultraviolet radiation need to be well characterised to provide accurate and reliable data. Since the characterisation and calibration are usually performed in the laboratory under conditions very different from those encountered during solar measurements, it is essential to address all issues concerned with the representativity of the laboratory characterisation with respect to the solar measurements. These include among others the instrument stability, the instrument linearity, the instrument responsivity, the wavelength accuracy, the spectral resolution, stray light rejection and the instrument dependence on ambient temperature fluctuations. These instrument parameters need to be determined often enough so that the instrument changes only marginally in the period between successive characterisations and therefore provides reliable data for the intervening period.

Assessment of a Targeted Trap-Neuter-Return Pilot Study in Auckland, New Zealand

PubMed Central

Zito, Sarah; Vigeant, Shalsee; Dale, Arnja

2018-01-01

Simple Summary It is generally accepted that stray cats need to be managed to minimise the associated negative impacts and there is a need for effective and humane management tools. One such potential tool is trap-neuter-return (TNR), which anecdotally has been used in New Zealand to manage stray cats, but no concerted and targeted implementation of this technique has been reported, nor any formal assessments conducted. A targeted TNR (TTNR) programme for urban stray cats was implemented and assessed in one Auckland suburb. Assessment was based on the number of incoming felines; stray, unsocialised cats euthanased; unsocialised, unowned cats sterilised and returned (independently of the TTNR programme); and neonatal/underage euthanasias. Incoming stray feline, underage euthanasia, and unsocialised stray cat euthanasia numbers all reduced for the targeted suburb when these outcome measures were compared for the years before and after the programme. These outcome measures had a greater reduction in the targeted suburb compared to the other Auckland suburbs not targeted by the TTNR programme, although causation cannot be inferred, as a variety of reasons could have contributed to the changes. This pilot programme suggests that TTNR could be a valuable humane cat management tool in urban New Zealand, and further assessment is warranted. Abstract There is a need for effective and humane management tools to manage urban stray cats and minimise negative impacts associated with stray cats. One such tool is targeted trap-neuter-return (TTNR), but no concerted implementation of this technique or formal assessments have been reported. To address this deficit, a TTNR programme was implemented and assessed in one Auckland suburb from May 2015 to June 2016; the programme sterilised and returned 348 cats (4.2 cats/1000 residents). Assessment was based on the number of incoming felines; stray, unsocialised cats euthanased; unsocialised, unowned cats sterilised and returned (independently of the TTNR programme); and neonatal/underage euthanasias. Incoming stray felines, underage euthanasias, and unsocialised stray cat euthanasias were all reduced for the targeted suburb when compared for the years before and after the programme (the percentage reduction in these parameters was −39, −17, −34, −7, and −47, respectively). These outcome measures had a greater reduction in the targeted suburb compared to the Auckland suburbs not targeted by the TTNR programme (p < 0.01), although causation cannot be inferred, as a variety of reasons could have contributed to the changes. This pilot programme suggests that TTNR could be a valuable, humane cat management tool in urban New Zealand, and further assessment is warranted. PMID:29757255

Prevalence of external ear disorders in Belgian stray cats.

PubMed

Bollez, Anouck; de Rooster, Hilde; Furcas, Alessandra; Vandenabeele, Sophie

2018-02-01

Objectives Feline otitis externa is a multifactorial dermatological disorder about which very little is known. The objective of this study was to map the prevalence of external ear canal disorders and the pathogens causing otitis externa in stray cats roaming around the region of Ghent, Belgium. Methods One hundred and thirty stray cats were randomly selected during a local trap-neuter-return programme. All cats were European Shorthairs. This study included clinical, otoscopic and cytological evaluation of both external ears of each cat. Prospective data used as parameters in this study included the sex, age and body condition score of each cat, as well as the presence of nasal and/or ocular discharge, and the results of feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) Snap tests. Results Remarkably, very few (sub)clinical problems of the external ear canal were found in the stray cat population. Malassezia species was by far the most common organism found in the external ear canals of the 130 stray cats. A total of 96/130 (74%) cats were found to have Malassezia species organisms present in one or both ears based on the cytological examination. No correlation was found between the parameters of sex, age, body condition score, the presence of nasal and/or ocular discharge and FIV and FeLV status, and the presence of parasites, bacteria or yeasts. Conclusions and relevance This study provides more information about the normal state of the external ear canal of stray cats. The ears of most stray cats are relatively healthy. The presence of Malassezia species organisms in the external ear canal is not rare among stray cats.

Design of 3x3 Focusing Array for Heavy Ion Driver Final Report on CRADA TC-02082-04

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martovetsky, N.

This memo presents a design of a 3x3 quadrupole array for HIF. It contains 3 D magnetic field computations of the array build with racetrack coils with and without different shields. It is shown that it is possible to have a low error magnetic field in the cells and shield the stray fields to acceptable levels. The array design seems to be a practical solution to any size array for future multi-beam heavy ion fusion drivers.

Dichroic filters to protect milliwatt far-infrared detectors from megawatt ECRH radiation.

PubMed

Bertschinger, G; Endres, C P; Lewen, F; Oosterbeek, J W

2008-10-01

Dichroic filters have been used to shield effectively the far infrared (FIR) detectors at the interferometer/polarimeter on TEXTOR. The filters consist of metal foils with regular holes, the hole diameter, the mutual spacing and the thickness of the foils are chosen to transmit radiation at the design frequency with transmission >90%. The attenuation at the low frequency end of the bandpass filter is about 30 dB per octave, the high frequency transmission is between 20% and 40%. The filters have been used to block the stray radiation from the megawatt microwave heating beam to the detectors of the FIR interferometer, operating with power on the detector in the milliwatt range. If required, the low frequency attenuation can be still enhanced, without compromising the transmission in the passband. The FIR interferometer used for plasma density and position control is no longer disturbed by electromagnetic waves used for plasma heating.

Electric-field-induced magnetic domain writing in a Co wire

NASA Astrophysics Data System (ADS)

Tanaka, Yuki; Hirai, Takamasa; Koyama, Tomohiro; Chiba, Daichi

2018-05-01

We have demonstrated that the local magnetization in a Co microwire can be switched by an application of a gate voltage without using any external magnetic fields. The electric-field-induced reversible ferromagnetic phase transition was used to realize this. An internal stray field from a ferromagnetic gate electrode assisted the local domain reversal in the Co wire. This new concept of electrical domain switching may be useful for dramatically reducing the power consumption of writing information in a magnetic racetrack memory, in which a shift of a magnetic domain by electric current is utilized.

Hyperspectral radiometer for automated measurement of global and diffuse sky irradiance

NASA Astrophysics Data System (ADS)

Kuusk, Joel; Kuusk, Andres

2018-01-01

An automated hyperspectral radiometer for the measurement of global and diffuse sky irradiance, SkySpec, has been designed for providing the SMEAR-Estonia research station with spectrally-resolved solar radiation data. The spectroradiometer has been carefully studied in the optical radiometry laboratory of Tartu Observatory, Estonia. Recorded signals are corrected for spectral stray light as well as for changes in dark signal and spectroradiometer spectral responsivity due to temperature effects. Comparisons with measurements of shortwave radiation fluxes made at the Baseline Surface Radiation Network (BSRN) station at Tõravere, Estonia, and with fluxes simulated using the atmospheric radiative transfer model 6S and Aerosol Robotic Network (AERONET) data showed that the spectroradiometer is a reliable instrument that provides accurate estimates of integrated fluxes and of their spectral distribution. The recorded spectra can be used to estimate the amount of atmospheric constituents such as aerosol and column water vapor, which are needed for the atmospheric correction of spectral satellite images.

Health and Ecological Aspects of Stray Cats in Old San Juan, Puerto Rico: Baseline Information to Develop an Effective Control Program.

PubMed

Castro-Prieto, Jessica; Andrade-Núñez, Maria José

2018-06-01

The overpopulation of stray cats in urban areas represents a potential risk for humans, as stray cats may carry diseases, such as toxoplasmosis, and virus such as rabies, the feline immunodeficiency, and the feline leukemia. In Old San Juan, a historic neighborhood and one of the most touristic places in Puerto Rico, there is an overpopulation of stray cats. In this study, we generated baseline information fundamental to developing a successful control program by estimating the stray cat population size, density, and spatial distribution. Furthermore, we quantified the number of neutered cats and developed a spatial database to include information about the external physical condition of each individual. We estimated a population of 178 (±21) cats, with a density of 3.6 cats/ha. Overall, we observed 209 cats, from which 149 (71%) were identified as new and 60 (29%) were recaptured. We found stray cats had a significant non-random and clustered spatial distribution (z-score = -19.39 SD; ratio = 0.29; p<0.0001), with an observable larger abundance in residential zones where food was provided. A total of 105 (70%) cats were neutered, and 32 (21%) individuals exhibited very poor physical conditions, including skin problems, scars, underweight, and blindness. We concluded that the ecological and descriptive data generated in this study are essential for an effective control of stray cats and their potential impacts on humans living in this neighborhood.

Monte Carlo simulations for angular and spatial distributions in therapeutic-energy proton beams

NASA Astrophysics Data System (ADS)

Lin, Yi-Chun; Pan, C. Y.; Chiang, K. J.; Yuan, M. C.; Chu, C. H.; Tsai, Y. W.; Teng, P. K.; Lin, C. H.; Chao, T. C.; Lee, C. C.; Tung, C. J.; Chen, A. E.

2017-11-01

The purpose of this study is to compare the angular and spatial distributions of therapeutic-energy proton beams obtained from the FLUKA, GEANT4 and MCNP6 Monte Carlo codes. The Monte Carlo simulations of proton beams passing through two thin targets and a water phantom were investigated to compare the primary and secondary proton fluence distributions and dosimetric differences among these codes. The angular fluence distributions, central axis depth-dose profiles, and lateral distributions of the Bragg peak cross-field were calculated to compare the proton angular and spatial distributions and energy deposition. Benchmark verifications from three different Monte Carlo simulations could be used to evaluate the residual proton fluence for the mean range and to estimate the depth and lateral dose distributions and the characteristic depths and lengths along the central axis as the physical indices corresponding to the evaluation of treatment effectiveness. The results showed a general agreement among codes, except that some deviations were found in the penumbra region. These calculated results are also particularly helpful for understanding primary and secondary proton components for stray radiation calculation and reference proton standard determination, as well as for determining lateral dose distribution performance in proton small-field dosimetry. By demonstrating these calculations, this work could serve as a guide to the recent field of Monte Carlo methods for therapeutic-energy protons.

Development of helium electron cyclotron wall conditioning on TCV

NASA Astrophysics Data System (ADS)

Douai, D.; Goodman, T.; Isayama, A.; Fukumoto, M.; Wauters, T.; Sozzi, C.; Coda, S.; Blanchard, P.; Figini, L.; Garavaglia, S.; Miyata, Y.; Moro, A.; Ricci, D.; Silva, M.; Theiler, C.; Vartanian, S.; Verhaegh, K.; the EUROfusion MST1 Team; the TCV Team

2018-02-01

JT-60SA envisions electron cyclotron wall conditioning (ECWC), as wall conditioning method in the presence of the toroidal field to control fuel and impurity recycling and to improve plasma performance and reproducibility. This paper reports on Helium ECWC experiments on TCV in support of JT-60SA operation. Nearly sixty Helium conditioning discharges have been successfully produced in TCV, at a toroidal field B T  =  1.3 or 1.54 T, with gyrotrons at 82.7 GHz in X2 mode, mimicking ECWC operation in JT-60SA at the second harmonic of the EC wave. Discharge parameters were tuned in order to (i) minimize the time for the onset of ECWC plasmas, thus minimizing absorption of stray radiation by in-vessel components, (ii) improve discharge homogeneity by extending the discharge vertically and radially, and wall coverage, in particular of inboard surfaces where JT-60SA plasmas will be initiated, (iii) assess the efficiency of He-ECWC to deplete carbon walls from fuel. An optimized combination of vertical and radial magnetic fields, with amplitudes typically 0.1 to 0.6% of that of B T, has been determined, which resulted in lowest breakdown time, improved wall coverage and enhanced fuel removal. A standard ohmic D 2-plasma could be then sustained, whereas it would not have been possible without He-ECWC.

The physics of proton therapy.

PubMed

Newhauser, Wayne D; Zhang, Rui

2015-04-21

The physics of proton therapy has advanced considerably since it was proposed in 1946. Today analytical equations and numerical simulation methods are available to predict and characterize many aspects of proton therapy. This article reviews the basic aspects of the physics of proton therapy, including proton interaction mechanisms, proton transport calculations, the determination of dose from therapeutic and stray radiations, and shielding design. The article discusses underlying processes as well as selected practical experimental and theoretical methods. We conclude by briefly speculating on possible future areas of research of relevance to the physics of proton therapy.

The physics of proton therapy

PubMed Central

Newhauser, Wayne D; Zhang, Rui

2015-01-01

The physics of proton therapy has advanced considerably since it was proposed in 1946. Today analytical equations and numerical simulation methods are available to predict and characterize many aspects of proton therapy. This article reviews the basic aspects of the physics of proton therapy, including proton interaction mechanisms, proton transport calculations, the determination of dose from therapeutic and stray radiations, and shielding design. The article discusses underlying processes as well as selected practical experimental and theoretical methods. We conclude by briefly speculating on possible future areas of research of relevance to the physics of proton therapy. PMID:25803097

Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets.

PubMed

Chou, Ching-Yu; Ferrage, Fabien; Aubert, Guy; Sakellariou, Dimitris

2015-07-17

Standard Magnetic Resonance magnets produce a single homogeneous field volume, where the analysis is performed. Nonetheless, several modern applications could benefit from the generation of multiple homogeneous field volumes along the axis and inside the bore of the magnet. In this communication, we propose a straightforward method using a combination of ring structures of permanent magnets in order to cancel the gradient of the stray field in a series of distinct volumes. These concepts were demonstrated numerically on an experimentally measured magnetic field profile. We discuss advantages and limitations of our method and present the key steps required for an experimental validation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meinke, Rainer B.; Goodzeit, Carl L.; Ball, Millicent J.

This research project advanced the development of reliable, cost-effective arrays of superconducting quadrupole magnets for use in multi-beam inertial fusion accelerators. The field in each array cell must be identical and meet stringent requirements for field quality and strength. An optimized compact array design using flat double-layer pancake coils was developed. Analytical studies of edge termination methods showed that it is feasible to meet the requirements for field uniformity in all cells and elimination of stray external field in several ways: active methods that involve placement of field compensating coils on the periphery of the array or a passive methodmore » that involves use of iron shielding.« less

SeaWiFS Technical Report Series. Volume 41; Case Studies for SeaWiFS Calibration and Validation

NASA Technical Reports Server (NTRS)

Yeh, Eueng-nan; Barnes, Robert A.; Darzi, Michael; Kumar, Lakshmi; Early, Edward A.; Johnson, B. Carol; Mueller, James L.; Trees, Charles C.

1997-01-01

This document provides brief reports, or case studies, on a number of investigations sponsored by the Calibration and Validation Team (CVT) within the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project. Chapter I describes the calibration and characterization of the GSFC sphere, which was used in the recent recalibration of the SeaWiFS instrument. Chapter 2 presents a revision of the diffuse attenuation coefficient, K(490), algorithm based on the SeaWiFS wavelengths. Chapter 3 provides an implementation scheme for an algorithm to remove out-of-band radiance when using a sensor calibration based on a finite width (truncated) spectral response function, e.g., between the 1% transmission points. Chapter 4 describes the implementation schemes for the stray light quality flag (local area coverage [LAC] and global area coverage [GAC]) and the LAC stray light correction.

Assembling a ring-shaped crystal in a microfabricated surface ion trap

DOE PAGES

Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco; ...

2015-09-01

We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca + ions with an average separation of 9 μm comprise the ion crystal.

Assembling a ring-shaped crystal in a microfabricated surface ion trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco

We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca + ions with an average separation of 9 μm comprise the ion crystal.

Salmon restoration in the Umatilla River: A study of straying and risk containment

USGS Publications Warehouse

Hayes, M.C.; Carmichael, R.W.

2002-01-01

The use of artificial propagation may produce unexpected results and the need for risk containment. Stray chinook salmon (Oncorhynchus tshawytscha) from Umatilla River releases put the threatened Snake River stock at risk, caused conflict between two plans, altered management, and greatly increased the costs for hatchery-based restoration. Stray Umatilla returns captured or observed in the Snake River averaged more than 200 fish annually and comprised up to 26% of the escapement. The risk to the threatened population stimulated a series of containment actions, including wire tagging 2-3 million fish annually, use of acclimation ponds, altering release locations, flow enhancement, and broodstock management changes. Actions for the use of artificial propagation where straying or unexpected results are a concern include marking or tagging most or all fish, limiting the number of fish initially released, recognizing environmental variables that influence straying, ensuring that funding for risk containment is available when undesirable results occur, and recognizing that unexpected results may not be manifested or identified immediately.

Fast and accurate modeling of stray light in optical systems

NASA Astrophysics Data System (ADS)

Perrin, Jean-Claude

2017-11-01

The first problem to be solved in most optical designs with respect to stray light is that of internal reflections on the several surfaces of individual lenses and mirrors, and on the detector itself. The level of stray light ratio can be considerably reduced by taking into account the stray light during the optimization to determine solutions in which the irradiance due to these ghosts is kept to the minimum possible value. Unhappily, the routines available in most optical design software's, for example CODE V, do not permit all alone to make exact quantitative calculations of the stray light due to these ghosts. Therefore, the engineer in charge of the optical design is confronted to the problem of using two different software's, one for the design and optimization, for example CODE V, one for stray light analysis, for example ASAP. This makes a complete optimization very complex . Nevertheless, using special techniques and combinations of the routines available in CODE V, it is possible to have at its disposal a software macro tool to do such an analysis quickly and accurately, including Monte-Carlo ray tracing, or taking into account diffraction effects. This analysis can be done in a few minutes, to be compared to hours with other software's.

Urban stray cats infested by ectoparasites with zoonotic potential in Greece.

PubMed

Lefkaditis, Menelaos A; Sossidou, Anna V; Panorias, Alexandros H; Koukeri, Smaragda E; Paştiu, Anamaria I; Athanasiou, Labrini V

2015-10-01

A large population of stray cats is encountered in many urban areas sharing the same environment with people, usually being in a close direct contact with them. A variety of ectoparasites can infest such cats, causing mild dermatological abnormalities to more severe systemic disorders. In order to determine the extent of which stray cats carry ectoparasites, particularly those of zoonotic potential, 341 stray cats originating from the urban area of Thessaloniki, Greece, were examined between 2012 and 2014. The signalment of each cat such as gender, hair length, and roughly estimated age were recorded. From a total of 341 examined stray cats, 127 (37.24%; 95% confidence interval (CI) 32.14-42.64) were infested with at least one of the following ectoparasites: mites-Otodectes cynotis (15.8%), Notoedres cati (2.35%), Cheyletiella blakei (2.05%); fleas-Ctenocephalides felis (24.3%); ticks-Rhipicephalus sanguineus (0.88%); and lice-Felicola subrostratus (0.59%). A significantly higher prevalence of ectoparasites was observed in long-haired individuals (p < 0.00001). The above ectoparasites may either cause or transmit diseases not only in cats but also in humans Therefore, antiparasitic control should be included in stray cat neutering campaigns while public health education for taking preventive measures will decrease the risk of transmission to humans.

Spirocercosis in owned and stray dogs in Grenada.

PubMed

Chikweto, A; Bhaiyat, M I; Tiwari, K P; de Allie, C; Sharma, R N

2012-12-21

The aim of this retrospective study was to estimate the prevalence of Spirocerca lupi and its associated lesions in owned and stray dogs in Grenada. During 2001-2011 necropsies were carried out on 1022 owned and 450 stray dogs at the pathology diagnostic laboratory, School of Veterinary Medicine, St. George's University, Grenada. Lesions due to S. lupi characterized by focal to multifocal granulomatous esophagitis with aneurysms, mineralized plaques and nodules in the adjacent thoracic aorta were found in 90 (8.8%; 95% confidence interval, 7.1-10.5%) of owned dogs and 64 (14.2%; 95% CI, 11.2-17.6%) of stray dogs. Stray dogs were significantly more affected by spirocercosis than owned dogs (p=0.0022). Of the 90 owned dogs with spirocercosis, 3 dogs had aberrant migration to the thoracic vertebral column with resultant spondylitis; 1 dog each had aberrant migration involving the stomach and the lung. Two dogs had ruptured aorta with hemothorax. Among the 64 stray dogs with spirocercosis, one dog had an esophageal granuloma that transformed into a fibroblastic osteosarcoma; spondylitis due to aberrant migration of S. lupi and hypertrophic osteopathy. We report spirocercosis for the first time in the dogs from a tropical island of Grenada. Copyright © 2012 Elsevier B.V. All rights reserved.

Plasma interface of the EC waves to the LHD peripheral region

NASA Astrophysics Data System (ADS)

Kubo, S.; Igami, H.; Tsujimura, T. I.; Shimozuma, T.; Takahashi, H.; Yoshimura, Y.; Nishiura, M.; Makino, R.; Mutoh, T.

2015-12-01

In order to realize an efficient ECRH and also to reduce stray radiation due to non-absorbed power during ECRH, it is necessary to excite a wave that is absorbed well near the electron cyclotron resonance. In the normal fusion magnetic field confinement machine and in the electron cyclotron frequency range, WKB approximation is valid almost all the way from antenna to the absorption region due to the large scale-length of the plasma density λn and the magnetic shear τs as compared with the local wavelength λ0. In these situation, it is well known that the O/X mode propagates as O/X mode if τs ≫ λ0. Even in these situation, if τs and λn are comparable and |1/λO-1/λX|τs ≪ 1, there still remains the question from where "X" - or "O" - mode become "X" - or "O" mode at the peripheral region. In order to simulate this situation, one dimensional full wave calculation code which solve electromagnetic wave equation under arbitrary magnetic field configuration and arbitrary density profile for a given polarization state are developed and incorporated in the upgraded ray tracing code LHDGauss. It is tried to find the density and shear scale lengths region where the mode mixing effect is not negligible.

Condition monitoring of Electric Components

NASA Astrophysics Data System (ADS)

Zaman, Ishtiaque

A universal non-intrusive model of a flexible antenna array is presented in this paper to monitor and identify the failures in electric machines. This adjustable antenna is designed to serve the purpose of condition monitoring of a vast range of electrical components including Induction Motor (IM), Printed Circuit Board (PCB), Synchronous Reluctance Motor (SRM), Permanent Magnet Synchronous Machine (PMSM) etc. by capturing the low frequency magnetic field radiated around these machines. The basic design and specification of the proposed antenna array for low frequency components is portrayed first. The design of the antenna is adjustable to fit for an extensive variety of segments. Subsequent to distinguishing the design and specifications of the antenna, the ideal area of the most delicate stray field has been identified for healthy current streaming around the machineries. Following this, short circuit representing faulty situation has been introduced and compared with the healthy cases. Precision has been found recognizing the faults using this one generic model of Antenna and the results are presented for three different machines i.e. IM, SRM and PMSM. Finite element method has been used to design the antenna and detect the optimum location and faults in the machines. Finally, a 3D Printer is proposed to be employed to build the antenna as per the details tended to in this paper contingent upon the power segments.

Conceptual design of a stray light facility for Earth observation satellites

NASA Astrophysics Data System (ADS)

Stockman, Y.; Hellin, M. L.; Marcotte, S.; Mazy, E.; Versluys, J.; François, M.; Taccola, M.; Zuccaro Marchi, A.

2017-11-01

With the upcoming of TMA or FMA (Three or Four Mirrors Anastigmat) telescope design in Earth Observation system, stray light is a major contributor to the degradation of the image quality. Numerous sources of stray light can be identified and theoretically evaluated. Nevertheless in order to build a stray light model of the instrument, the Point Spread Function(s) of the instrument, i.e., the flux response of the instrument to the flux received at the instrument entrance from an infinite distant point source needs to be determined. This paper presents a conceptual design of a facility placed in a vacuum chamber to eliminate undesired air particles scatter light sources. The specification of the clean room class or vacuum will depend on the required rejection to be measured. Once the vacuum chamber is closed, the stray light level from the external environment can be considered as negligible. Inside the chamber a dedicated baffle design is required to eliminate undesired light generated by the set up itself e.g. retro reflected light away from the instrument under test. This implies blackened shrouds all around the specimen. The proposed illumination system is a 400 mm off axis parabolic mirror with a focal length of 2 m. The off axis design suppresses the problem of stray light that can be generated by the internal obstruction. A dedicated block source is evaluated in order to avoid any stray light coming from the structure around the source pinhole. Dedicated attention is required on the selection of the source to achieve the required large measurement dynamic.

A Survey of Public Opinion on Cat (Felis catus) Predation and the Future Direction of Cat Management in New Zealand

PubMed Central

Walker, Jessica K.; Bruce, Stephanie J.; Dale, Arnja R.

2017-01-01

Simple Summary The need to balance the benefits of cat ownership with the prevention of wildlife predation in New Zealand evokes strong and opposing views. This paper evaluates public concern for wildlife predation by four categories of cats; owned cats, managed-stray cats, unmanaged-stray cats, and feral cats. In addition, public support for a National Cat Management Strategy and a range of management techniques are investigated. Although the participants expressed concern regarding wildlife predation by all four categories of cats, the highest levels of concern were predation by feral cats, followed by unmanaged stray cats, then managed stray cats, and finally owned cats. The large majority of participants were found to support the implementation of a National Cat Management Strategy. Management techniques for owned cats that obtained public support included; cat exclusion zones, limits on ownership numbers, microchipping, Council registration, and de-sexing. Trap-Neuter-Return (TNR) was the favoured management technique for managed stray cats, while TNR and lethal management techniques were equally favoured for unmanaged stray cats. Lethal control methods were favoured for feral cats. The findings presented in this paper will be useful to consider during the development of legislation relating to cat management and predation in New Zealand. Abstract Cat predation is a prominent issue in New Zealand that provokes strong and opposing views. We explored, via 1011 face-to-face questionnaires, public opinion on (a) support for a National Cat Management Strategy (78% support); (b) concern regarding predation of wildlife by owned and un-owned cats (managed stray, unmanaged stray, and feral cats); (c) the acceptability of management techniques for owned cats; and (d) the acceptability of population management techniques for un-owned cats. The highest concern was expressed regarding the predation of non-native and native wildlife by feral cats (60 and 86% repectively), followed by unmanaged stray cats (59 and 86% respectively), managed stray cats (54 and 82% respectively), and finally owned cats (38 and 69% repectively). Limits to the number of cats owned and cat restriction zones received high levels of support (>65%), and compulsory microchipping, Council registration, and de-sexing were supported by the majority (>58%). Public support of population control methods for unowned cats was explored, and the influence of participant demographic variables on responses is described. These findings provide insight into public opinion regarding the management of cats in New Zealand, which should be considered during the development of legislation in this area. PMID:28671609

Enhanced-Adhesion Multi-Walled Carbon Nanotubes on Titanium Substrates for Stray Light Control

NASA Technical Reports Server (NTRS)

Hagopian, John; Getty, Stephanie; Quijada, Manuel

2012-01-01

Carbon nanotubes previously grown on silicon have extremely low reflectance, making them a good candidate for stray light suppression. Silicon, however, is not a good structural material for stray light components such as tubes, stops, and baffles. Titanium is a good structural material and can tolerate the 700 C nanotube growth process. The ability to grow carbon nanotubes on a titanium substrate that are ten times blacker than the current NASA state-of-the-art paints in the visible to near infrared spectra has been achieved. This innovation will allow significant improvement of stray light performance in scientific instruments or any other optical system. This innovation is a refinement of the utilization of multiwalled carbon nano tubes for stray light suppression in spaceflight instruments. The innovation is a process to make the surface darker and improve the adhesion to the substrate, improving robustness for spaceflight use. Bright objects such as clouds or ice scatter light off of instrument structures and components and make it difficult to see dim objects in Earth observations. A darker material to suppress this stray light has multiple benefits to these observations, including enabling scientific observations not currently possible, increasing observational efficiencies in high-contrast scenes, and simplifying instruments and lowering their cost by utilizing fewer stray light components and achieving equivalent performance. The prior art was to use commercially available black paint, which resulted in approximately 4% of the light being reflected (hemispherical reflectance or total integrated scatter, or TIS). Use of multiwalled carbon nanotubes on titanium components such as baffles, entrance aperture, tubes, and stops, can decrease this scattered light by a factor of ten per bounce over the 200-nm to 2,500-nm wavelength range. This can improve system stray light performance by orders of magnitude. The purpose of the innovation is to provide an enhanced stray light control capability by making a blacker surface treatment for typical stray light control components. Since baffles, stops, and tubes used in scientific observations often undergo loads such as vibration, it was critical to develop this surface treatment on structural materials. The innovation is to optimize the carbon nanotube growth for titanium, which is a strong, lightweight structural material suitable for spaceflight use. The titanium substrate carbon nanotubes are more robust than those grown on silicon and allow for easier utilization. They are darker than current surface treatments over larger angles and larger wavelength range. The primary advantage of titanium substrate is that it is a good structural material, and not as brittle as silicon.

Calibration of passive remote observing optical and microwave instrumentation; Proceedings of the Meeting, Orlando, FL, Apr. 3-5, 1991

NASA Technical Reports Server (NTRS)

Guenther, Bruce W. (Editor)

1991-01-01

Various papers on the calibration of passive remote observing optical and microwave instrumentation are presented. Individual topics addressed include: on-board calibration device for a wide field-of-view instrument, calibration for the medium-resolution imaging spectrometer, cryogenic radiometers and intensity-stabilized lasers for EOS radiometric calibrations, radiometric stability of the Shuttle-borne solar backscatter ultraviolet spectrometer, ratioing radiometer for use with a solar diffuser, requirements of a solar diffuser and measurements of some candidate materials, reflectance stability analysis of Spectralon diffuse calibration panels, stray light effects on calibrations using a solar diffuser, radiometric calibration of SPOT 23 HRVs, surface and aerosol models for use in radiative transfer codes. Also addressed are: calibrated intercepts for solar radiometers used in remote sensor calibration, radiometric calibration of an airborne multispectral scanner, in-flight calibration of a helicopter-mounted Daedalus multispectral scanner, technique for improving the calibration of large-area sphere sources, remote colorimetry and its applications, spatial sampling errors for a satellite-borne scanning radiometer, calibration of EOS multispectral imaging sensors and solar irradiance variability.

Control of Mechanical Stresses of High Pressure Container Walls by Magnetoelastic Method

NASA Astrophysics Data System (ADS)

Kulak, S. M.; Novikov, V. F.; Baranov, A. V.

2016-10-01

Deformations of the walls of pressure vessels arising in the process of testing and operation, as well as reduce their thickness due to corrosion, to create the prerequisites for the growth of mechanical stresses which accelerating the processes of strain aging, embrittlement of the material and reducing its fatigue properties. This article is devoted to researches of the magnetoelastic demagnetization in the wall of steel vessel of loading by internal pressure. It is established that the increasing pressure on the vessel wall is accompanied by a monotonic decrease in the intensity of the magnetic stray field of local magnetization of steel. It is shown that a magnetic stray field of local magnetization of the wall of steel vessel is non-uniform due to differences in structure and stresses. It is proposed to use the obtained results to control the stress state of vessels, experiencing multi-axial loads generated by internal pressure (pipelines, oil tanks, etc.) The method of magnetoelastic of the demagnetization of the steel has a high sensitivity to mechanical stress, the simplicity of implementation and expressiveness compared to the strain gauge and method of coercive force.

Preliminary Design of the Vacuum System for FAIR Super FRS Quadrupole Magnet Cryostat

NASA Astrophysics Data System (ADS)

Akhter, J.; Pal, G.; Datta, A.; Sarma, P. R.; Bhunia, U.; Roy, S.; Bhattacharyya, S.; Nandi, C.; Mallik, C.; Bhandari, R. K.

2012-11-01

The Super-Conducting Fragment Separator (Super FRS) of the Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt is a large-acceptance superonducting fragment separator. The separator consists of large dipole, quadrupole and hexapole superconducting magnets. The long quadrupole magnet cryostat houses the helium chamber, which has the magnet iron and NbTi superconducting coil. The magnet weighs about 30 tons. The helium chamber is enclosed in vacuum inside the magnet cryostat. Multilayer Insulation (MLI) will be wrapped around the thermal shield to reduce radiation loss. Polyster of MLI comprises the major component responsible for outgassing. In order to reduce outgassing, pumping at elevated temperatures has to be carried out. In view of the large size and weight of the magnet, a seal off approach might not be operationally feasible. Continuous pumping of the cryostat has also been examined. Pump has been kept at a distance from the magnet considering the effect of stray magnetic fields. Oil free turbo molecular pump and scroll pump combination will be used to pump down the cryostat. The ultimate heat load of the cryostat will be highly dependent on the pressure attained. Radiation and conduction plays an important role in the heat transfer at low temperatures. This paper presents the vacuum design of the long quadrupole magnet cryostat and estimates the heat load of the cryostat.

Near-field interaction between domain walls in adjacent permalloy nanowires

NASA Astrophysics Data System (ADS)

O'Brien, Liam

2010-03-01

A domain wall (DW) moving in a ferromagnetic nanowire may interact with the stray field from another DW travelling in an adjacent wire. This could greatly impact the operation of proposed DW based data storage schemes which rely on the controlled propagation of DWs in densely packed nanowires [1, 2]. Here we experimentally study the interaction between two DWs travelling in adjacent Permalloy nanowires [3]. We find that the interaction causes significant pinning, with measured pinning fields of up to 93 Oe (˜5 times the intrinsic pinning field of an isolated wire) for the smallest separations. We present an analysis of the observed pinning field dependence on wire separation in terms of the full magnetostatic charge distribution within a DW. By considering an isolated DW, and accounting for finite temperature, it is possible to fully reproduce the experimentally observed dependence. This suggests that the DW internal structure is not appreciably perturbed by the interaction and so remains rigid, consistent with a finite sized quasi-particle description [4]. The full charge distribution must be considered in understanding these near-field interactions as other models based on simpler descriptions of the charge distribution within the DW, including a point-like distribution, cannot reproduce the observed dependence. Finally, we develop the idea of using localized stray fields to pin a DW and show how specific potential landscapes can be created by tailoring a pinning charge distribution, with the added advantage that neither DW internal structure nor nanowire geometry is appreciably perturbed. [4pt] [1] Allwood, Cowburn et al. Science 309, 1688 (2005) [0pt] [2] S. S. Parkin, Science 320, 190 (2008) [0pt] [3] O'Brien, Cowburn et al. Phys. Rev. Lett. 103, 7, 077206 (2009) [0pt] [4] Saitoh, Miyajima et al. Nature 432, 203 (2004)

National Ignition Facility main laser stray light analysis and control

DOE Office of Scientific and Technical Information (OSTI.GOV)

English, R E; Miller, J L; Peterson, G

1998-06-26

Stray light analysis has been carried out for the main laser section of the National Ignition Facility main laser section using a comprehensive non-sequential ray trace model supplemented with additional ray trace and diffraction propagation modeling. This paper describes the analysis and control methodology, gives examples of ghost paths and required tilted lenses, baffles, absorbers, and beam dumps, and discusses analysis of stray light "pencil beams" in the system.

Spontaneous Currents in Superconducting Systems with Strong Spin-Orbit Coupling

NASA Astrophysics Data System (ADS)

Mironov, S.; Buzdin, A.

2017-02-01

We show that Rashba spin-orbit coupling at the interface between a superconductor and a ferromagnet should produce a spontaneous current in the atomic thickness region near the interface. This current is counterbalanced by the superconducting screening current flowing in the region of the width of the London penetration depth near the interface. Such a current-carrying state creates a magnetic field near the superconductor surface, generates a stray magnetic field outside the sample edges, changes the slope of the temperature dependence of the critical field Hc 3 , and may generate the spontaneous Abrikosov vortices near the interface.

Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets

PubMed Central

Chou, Ching-Yu; Ferrage, Fabien; Aubert, Guy; Sakellariou, Dimitris

2015-01-01

Standard Magnetic Resonance magnets produce a single homogeneous field volume, where the analysis is performed. Nonetheless, several modern applications could benefit from the generation of multiple homogeneous field volumes along the axis and inside the bore of the magnet. In this communication, we propose a straightforward method using a combination of ring structures of permanent magnets in order to cancel the gradient of the stray field in a series of distinct volumes. These concepts were demonstrated numerically on an experimentally measured magnetic field profile. We discuss advantages and limitations of our method and present the key steps required for an experimental validation. PMID:26182891

Stray electrical currents in laparoscopic instruments used in da Vinci® robot-assisted surgery: an in vitro study.

PubMed

Mendez-Probst, Carlos E; Vilos, George; Fuller, Andrew; Fernandez, Alfonso; Borg, Paul; Galloway, David; Pautler, Stephen E

2011-09-01

The da Vinci(®) surgical system requires the use of electrosurgical instruments. The re-use of such instruments creates the potential for stray electrical currents from capacitive coupling and/or insulation failure. We used objective measures to report the prevalence and magnitude of such stray currents. Thirty-seven robotic instruments were tested using an electrosurgical unit (ESU) at pure coagulation and cut waveforms at four different settings. Conductive gel-coated instruments were tested at 40W, 80W, and maximum ESU output (coagulation 120W, cut 300W). The magnitude of stray currents was measured by an electrosurgical analyzer. At coagulation waveform in open air, 86% of instruments leaked a mean of 0.4W. In the presence of gel-coated instruments, stray currents were detected in all instruments with means (and standard deviation) of 3.4W (± 2), 4.1W (± 2.3), and 4.1W (± 2.3) at 40W, 80W, and 120W, respectively. At cut waveform in open air, none of the instruments leaked current, while gel-coated instruments leaked a mean of 2.2W (± 1.3), 2.2W (± 1.9) and 3.2W (± 1.9) at 40W, 80W, and 300W, respectively. All tested instruments in our study demonstrated energy leakage. Stray currents were higher during coagulation (high voltage) waveforms, and the magnitude was not always proportionate to the ESU settings. Stray currents have the potential to cause electrical burns. We support the programmed end of life of da Vinci instruments on the basis of safety. Consideration should be given to alternate energy sources or the adoption of active electrode monitoring technology to all monopolar instruments.

PCR-Based Molecular Characterization of Toxocara spp. Using Feces of Stray Cats: A Study from Southwest Iran

PubMed Central

Tavalla, Mahdi; Abdizadeh, Rahman; Hashemitabar, Mahmoud

2013-01-01

Feces of stray cat are potential sources of gastrointestinal parasites and play a crucial role in spreading and transmitting parasite eggs, larvae, and oocysts through contamination of soil, food, or water. In this study, we investigated the prevalence of Toxocara spp. infection in stray cats in Ahvaz city, southwest Iran. Eggs of Toxocara spp. in feces of stray cats were detected by the sucrose flotation method, and identification was conducted by polymerase chain reaction (PCR) and DNA sequencing. Of the 140 fecal samples that were randomly collected from public environments during the months of January to May 2012, 45% were found to harbour Toxocara spp. eggs. The highest prevalence of Toxocara spp. eggs was found in the central area of Ahvaz city (28.6%). T. canis eggs were found in 4 (6.34%) of the 63 positive samples. Stray cats are found in parks, playgrounds, and other public places and may be a potential contamination risk. Identification of Toxocara spp. using molecular methods is sufficiently sensitive to detect low levels of parasites and identify the different Toxocara spp. in feces. The relatively high prevalence of Toxocara spp. infection may continue to increase due to lack of effective environmental hygiene control in Iran. Consequently, there is a need to plan adequate programs to detect, identify, and control this infection as well as stray cats in the region. PMID:23755213

PCR-based molecular characterization of Toxocara spp. using feces of stray cats: a study from Southwest Iran.

PubMed

Khademvatan, Shahram; Rahim, Fakher; Tavalla, Mahdi; Abdizadeh, Rahman; Hashemitabar, Mahmoud

2013-01-01

Feces of stray cat are potential sources of gastrointestinal parasites and play a crucial role in spreading and transmitting parasite eggs, larvae, and oocysts through contamination of soil, food, or water. In this study, we investigated the prevalence of Toxocara spp. infection in stray cats in Ahvaz city, southwest Iran. Eggs of Toxocara spp. in feces of stray cats were detected by the sucrose flotation method, and identification was conducted by polymerase chain reaction (PCR) and DNA sequencing. Of the 140 fecal samples that were randomly collected from public environments during the months of January to May 2012, 45% were found to harbour Toxocara spp. eggs. The highest prevalence of Toxocara spp. eggs was found in the central area of Ahvaz city (28.6%). T. canis eggs were found in 4 (6.34%) of the 63 positive samples. Stray cats are found in parks, playgrounds, and other public places and may be a potential contamination risk. Identification of Toxocara spp. using molecular methods is sufficiently sensitive to detect low levels of parasites and identify the different Toxocara spp. in feces. The relatively high prevalence of Toxocara spp. infection may continue to increase due to lack of effective environmental hygiene control in Iran. Consequently, there is a need to plan adequate programs to detect, identify, and control this infection as well as stray cats in the region.

[Influence of different multifocal intraocular lens concepts on retinal stray light parameters].

PubMed

Ehmer, A; Rabsilber, T M; Mannsfeld, A; Sanchez, M J; Holzer, M P; Auffarth, G U

2011-10-01

Multifocal intraocular lenses (MIOL) are known to induce various photic phenomena depending on the optical principle. The aim of this study was to investigate the correlation between stray light measurements performed with the C-Quant (Oculus, Germany) and the results of a subjective patient questionnaire. In this study three different MIOLs were compared: AMO ReZoom (refractive design, n=10), AMO ZM900 (diffractive design, n=10) and Oculentis Mplus (near segment design, n=10). Cataract and refractive patients were enrolled in the study. Functional results were evaluated at least 3 months postoperatively followed by stray light measurements and a subjective questionnaire. Surgery was performed for all patients without complications. The three groups were matched for age, IOL power and corrected distance visual acuity (CDVA). Significantly different stray light (median) values log(s) were found (Kruskal-Wallis test, p<0.05): 1.12 log (refractive), 1.13 log (segment) and 1.28 log (diffractive). The subjective questionnaire did not show differences in glare perception but refractive MIOL patients noticed more halos surrounding light sources than the diffractive and segment MIOL patients. Stray light and subjective photopic phenomena do not show any basic correlation. Measurements in patients with refractive MIOLs showed less stray light than near segment or diffractive MIOLs. However, refractive MIOLs induced more halos compared to the other groups analyzed.

Road Killed Carnivores Illustrate the Status of Zoonotic Helminthes in Caspian Sea Littoral of Iran

PubMed Central

VAFAE ESLAHI, Aida; KIA, Eshrat Beigom; MOBEDI, Iraj; SHARIFDINI, Meysam; BADRI, Milad; MOWLAVI, Gholamreza

2017-01-01

Background: Carnivore carcasses on the roads can be regarded as study materials in parasitology and eco-epidemiology. Stray carnivores such as dogs and cats are known to harbor so many different pathogens like zoonotic helminthes. The current investigation, apparent the status of the helminthic parasites found in road killed carnivores from different parts of Guilan Province north of Iran. Methods: Fifty road killed carnivores including 27 stray dogs (Canis familiaris), 11 golden jackals (Canis aureus) and 12 stray cats (Felis catus) were collected from 21 locations of Guilan Province, during Apr to Nov 2015. Internal organs of the carcasses, including digestive tract, heart, kidneys, lungs, liver, skin, eyes as well as muscles were carefully inspected and sampled for helminthological investigation. Results: About 80% of the 50 carnivores, (stray dogs 77.77%, golden jackals 81.81%, and stray cats 91.66%) were found naturally infected with helminthic parasites. Dipylidum caninum, Toxocara cati, Toxocara canis, Toxascaris leonine, Ancylostoma caninum, Ancylostoma tubaeforme, Dirofilaria immitis, Dioctophyma renale, Dipylidum caninum, Echinococcus granulosus, Mesocestoides spp., Taenia hydatigena, Taenia hydatigera, Joyuxiella spp., Spirometra spp. are reported herein. Conclusion: The prevalent occurrence of zoonotic helminthes such as T. canis, T. cati, T. leonina, E. granulosus, D. immitis and D. renale in stray carnivores should be considered as a public health hazard, specifically within a vast tourism area like Guilan Province. PMID:28761483

Road Killed Carnivores Illustrate the Status of Zoonotic Helminthes in Caspian Sea Littoral of Iran.

PubMed

Vafae Eslahi, Aida; Kia, Eshrat Beigom; Mobedi, Iraj; Sharifdini, Meysam; Badri, Milad; Mowlavi, Gholamreza

2017-01-01

Carnivore carcasses on the roads can be regarded as study materials in parasitology and eco-epidemiology. Stray carnivores such as dogs and cats are known to harbor so many different pathogens like zoonotic helminthes. The current investigation, apparent the status of the helminthic parasites found in road killed carnivores from different parts of Guilan Province north of Iran. Fifty road killed carnivores including 27 stray dogs ( Canis familiaris ), 11 golden jackals ( Canis aureus ) and 12 stray cats ( Felis catus ) were collected from 21 locations of Guilan Province, during Apr to Nov 2015. Internal organs of the carcasses, including digestive tract, heart, kidneys, lungs, liver, skin, eyes as well as muscles were carefully inspected and sampled for helminthological investigation. About 80% of the 50 carnivores, (stray dogs 77.77%, golden jackals 81.81%, and stray cats 91.66%) were found naturally infected with helminthic parasites. Dipylidum caninum , Toxocara cati , Toxocara canis , Toxascaris leonine , Ancylostoma caninum , Ancylostoma tubaeforme , Dirofilaria immitis , Dioctophyma renale , Dipylidum caninum , Echinococcus granulosus , Mesocestoides spp ., Taenia hydatigena, Taenia hydatigera , Joyuxiella spp. , Spirometra spp. are reported herein. The prevalent occurrence of zoonotic helminthes such as T. canis , T. cati , T. leonina , E. granulosus , D. immitis and D. renale in stray carnivores should be considered as a public health hazard, specifically within a vast tourism area like Guilan Province.

What's in a name? Perceptions of stray and feral cat welfare and control in Aotearoa, New Zealand.

PubMed

Farnworth, Mark J; Campbell, Joanna; Adams, Nigel J

2011-01-01

New Zealanders (n = 354) rated the acceptability of lethal and nonlethal cat control methods and the importance of conservation and welfare. Lethal control was more acceptable for feral cats than strays; for nonlethal control, the inverse was true. More than concern for the welfare of cats subjected to control, perceived conservation benefits, risk of disease transfer, and companion cat welfare dictated the acceptability of control measures. Similarly, the welfare consideration for groups of cats differed, transitioning from companion (highest) to feral (lowest). Differences in attitudes toward acceptability of control methods were evident. In particular, nonhuman animal professionals ranked lethal control as more acceptable than did nonanimal professionals. Cat caregivers (owners) considered both conservation and welfare issues of greater importance than did nonowners. Owners ranked the acceptability of nonlethal control methods higher for stray cats, but not feral, than did nonowners. This research indicates that the use of the terms stray and feral may have significant impact on cats in New Zealand. There is also a greater consideration of conservation values than of welfare in stray and feral cat control.

Ultra-high field magnets for whole-body MRI

NASA Astrophysics Data System (ADS)

Warner, Rory

2016-09-01

For whole-body MRI, an ultra-high field (UHF) magnet is currently defined as a system operating at 7 T or above. Over 70 UHF magnets have been built, all with the same technical approach originally developed by Magnex Scientific Ltd. The preferred coil configuration is a compensated solenoid. In this case, the majority of the field is generated by a simple long solenoid that stretches the entire length of the magnet. Additional coils are wound on a separate former outside the main windings with the purpose of balancing the homogeneity. Most of the magnets currently in operation are passively shielded systems where the magnet is surrounded by a steel box of 200-870 tonnes of carbon steel. More recently actively shielded magnets have been built for operation at 7 T; in this case the stray field is controlled by with reverse turns wound on a separate former outside the primary coils. Protection against quench damage is much more complex with an actively shielded magnet design due to the requirement to prevent the stray field from increasing during a quench. In the case of the 7 T 900 magnet this controlled by combining some of the screening coils into each section of the protection circuit. Correction of the field variations caused by manufacturing tolerances and environmental effects are made with a combination of superconducting shims and passive shims. Modern UHF magnets operate in zero boil-off mode with the use of cryocoolers with cooling capacity at 4.2 K. Although there are no cryogen costs associated with normal operation UHF magnets require a significant volume (10 000-20 000 l) of liquid helium for the cool-down. Liquid helium is expensive therefore new methods of cool-down using high-power cryocoolers are being implemented to reduce the requirement.

Poster – 13: Evaluation of an in-house CCD camera film dosimetry imaging system for small field deliveries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalonde, Michel; Alexander, Kevin; Olding, Tim

Purpose: Radiochromic film dosimetry is a standard technique used in clinics to verify modern conformal radiation therapy delivery, and sometimes in research to validate other dosimeters. We are using film as a standard for comparison as we improve high-resolution three-dimensional gel systems for small field dosimetry; however, precise film dosimetry can be technically challenging. We report here measurements for fractionated stereotactic radiation therapy (FSRT) delivered using volumetric modulated arc therapy (VMAT) to investigate the accuracy and reproducibility of film measurements with a novel in-house readout system. We show that radiochromic film can accurately and reproducibly validate FSRT deliveries and alsomore » benchmark our gel dosimetry work. Methods: VMAT FSRT plans for metastases alone (PTV{sub MET}) and whole brain plus metastases (WB+PTV{sub MET}) were delivered onto a multi-configurational phantom with a sheet of EBT3 Gafchromic film inserted mid-plane. A dose of 400 cGy was prescribed to 4 small PTV{sub MET} structures in the phantom, while a WB structure was prescribed a dose of 200 cGy in the WB+PTV{sub MET} iterations. Doses generated from film readout with our in-house system were compared to treatment planned doses. Each delivery was repeated multiple times to assess reproducibility. Results and Conclusions: The reproducibility of film optical density readout was excellent throughout all experiments. Doses measured from the film agreed well with plans for the WB+PTV{sub MET} delivery. But, film doses for PTV{sub MET} only deliveries were significantly below planned doses. This discrepancy is due to stray/scattered light perturbations in our system during readout. Corrections schemes will be presented.« less

Experiences from First Top-Off Injection at the Stanford Synchrotron Radiation Lightsource

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bauer, J.M.; Liu, J.C.; Prinz, A.

2009-12-11

As the Stanford Synchrotron Radiation Lightsource (SSRL) of the SLAC National Accelerator Laboratory (SLAC) is moving toward Top-Off injection mode, SLAC's Radiation Protection Department is working with SSRL on minimizing the radiological hazards of this mode. One such hazard is radiation that is created inside the accelerator concrete enclosure by injected beam. Since during Top-Off injection the stoppers that would otherwise isolate the storage ring from the experimental area stay open, the stoppers no longer prevent such radiation from reaching the experimental area. The level of this stray radiation was measured in April 2008 during the first Top-Off injection tests.more » They revealed radiation dose rates of up to 18 microSv/h (1.8 millirem/h) outside the experimental hutches, significantly higher than our goal of 1 microSv/h (0.1 millirem/h). Non-optimal injection increased the measured dose rates by a factor two. Further tests in 2008 indicated that subsequent improvements by SSRL to the injection system have reduced the dose rates to acceptable levels. This presentation describes the studies performed before the Top-Off tests, the tests themselves and their major results (both under initial conditions and after improvements were implemented), and presents the controls being implemented for full and routine Top-Off injection.« less

The Impact of the Method of Gunshot Injury: War Injuries vs. Stray Bullets vs. Civilian Fighting.

PubMed

Mansor, Salah; Bodalal, Zuhir

2015-04-01

To analyze the impact of the method of Gunshot Injury (GSI) (i.e. war injuries, stray bullets, and civilian fighting) on patient morbidity and mortality. An observational study. Biostatistics Department of Al-Jalaa Hospital in Benghazi, Libya, from January to December 2011. Patients' records were analyzed with the method of gunshot injury as a classifying/comparative parameter. Age, gender, site of injury, receiving department, ICU admission, city of origin, length of stay, morbidity and mortality were determined and compared between the different methods of GSI. During the conflict, 1761 gunshot injuries were treated at the hospital. The method of injury was recorded for 62% (n=1096) of the cases and were classified under war injuries (72.2%, n=791), stray bullets (14.1%, n=155), and civilian fighting (13.7%, n=150). Nearly all the patients being treated for civilian fighting (98%, n=147) were males, (stray bullets, 82.6%, n=128, and war injuries 98.4%, n=778). Women were significantly less involved in a war injury (1.6%, n=13, p < 0.001). Stray bullets affected the younger age groups i.e. ² 19 years (26.5%, n=41) more than either fighting injuries (8%, n=12) or war injuries (11.8%, n=93, p < 0.001). Civilian fighting injuries (83.3%, n=125) mostly involved the 20-39 years age group (p < 0.001). Fighting wounds and stray bullets were more common in an urban (82.7%, n=124) rather than rural setting (p < 0.001); the same was true for stray bullets (76.8%, n = 119). The number of GSI's showed a close relationship with major events in society (i.e. military campaigns, celebration and civilian unrest). Significantly higher mortality rates were observed in civilian fighting injuries (7.7%, n=12, p=0.003) and stray bullets (10%, n=15, p=0.003) compared to general GSI's (5.2%, n=91) and war injuries (4.4%, n=35). Surgeons and general physicians need to be aware that GSI's differ in their salient features and outcome based on the method of injury.

Spin-Mechatronics

NASA Astrophysics Data System (ADS)

Matsuo, Mamoru; Saitoh, Eiji; Maekawa, Sadamichi

2017-01-01

We investigate the interconversion phenomena between spin and mechanical angular momentum in moving objects. In particular, the recent results on spin manipulation and spin-current generation by mechanical motion are examined. In accelerating systems, spin-dependent gauge fields emerge, which enable the conversion from mechanical angular momentum into spins. Such a spin-mechanical effect is predicted by quantum theory in a non-inertial frame. Experiments which confirm the effect, i.e., the resonance frequency shift in nuclear magnetic resonance, the stray field measurement of rotating metals, and electric voltage generation in liquid metals, are discussed.

Image Quality of the Helioseismic and Magnetic Imager (HMI) Onboard the Solar Dynamics Observatory (SDO)

NASA Technical Reports Server (NTRS)

Wachter, R.; Schou, Jesper; Rabello-Soares, M. C.; Miles, J. W.; Duvall, T. L., Jr.; Bush, R. I.

2011-01-01

We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light,image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.

Subsurface bending and reorientation of tilted vortex lattices in bulk isotropic superconductors due to Coulomb-like repulsion at the surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herrera, E.; Guillamón, I.; Galvis, J. A.

Here, we study vortex lattices (VLs) in superconducting weak-pinning platelet-like single crystals of β–Bi 2Pd in tilted magnetic fields with a scanning tunneling microscope. We show that vortices exit the sample perpendicular to the surface and are thus bent beneath the surface. The structure and orientation of the tilted VLs in the bulk are, for large tilt angles, strongly affected by Coulomb-type intervortex repulsion at the surface due to stray magnetic fields.

Subsurface bending and reorientation of tilted vortex lattices in bulk isotropic superconductors due to Coulomb-like repulsion at the surface

DOE PAGES

Herrera, E.; Guillamón, I.; Galvis, J. A.; ...

2017-11-03

Here, we study vortex lattices (VLs) in superconducting weak-pinning platelet-like single crystals of β–Bi 2Pd in tilted magnetic fields with a scanning tunneling microscope. We show that vortices exit the sample perpendicular to the surface and are thus bent beneath the surface. The structure and orientation of the tilted VLs in the bulk are, for large tilt angles, strongly affected by Coulomb-type intervortex repulsion at the surface due to stray magnetic fields.

Design of a synchrotron radiation detector for the test beam lines at the Superconducting Super Collider Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hutton, R.D.

1994-01-01

As part of the particle- and momentum-tagging instrumentation required for the test beam lines of the Superconducting Super Collider (SSC), the synchrotron radiation detector (SRD) was designed to provide electron tagging at momentum above 75 GeV. In a parallel effort to the three test beam lines at the SSC, schedule demands required testing and calibration operations to be initiated at Fermilab. Synchrotron radiation detectors also were to be installed in the NM and MW beam lines at Femilab before the test beam lines at the SSC would become operational. The SRD is the last instrument in a series of threemore » used in the SSC test beam fines. It follows a 20-m drift section of beam tube downstream of the last silicon strip detector. A bending dipole just in of the last silicon strip detector produces the synchrotron radiation that is detected in a 50-mm-square cross section NaI crystal. A secondary scintillator made of Bicron BC-400 plastic is used to discriminate whether it is synchrotron radiation or a stray particle that causes the triggering of the NaI crystal`s photo multiplier tube (PMT).« less

Seroepidemiological survey of helminthic parasites of stray dogs in Sari City, northern Iran.

PubMed

Gholami, Ishirzad; Daryani, Ahmad; Sharif, Mehdi; Amouei, Afsaneh; Mobedi, Iraj

2011-01-15

The objective of this study was to determine the prevalence rate of helminthic parasites in stray dogs' population especially zoonotic infections and to identify potential risk factors in the different areas of Sari city in Caspian area, north of Iran. During the period from April to September 2007, 50 stray dogs were collected from urban areas of Sari city. Recovered parasites were fixed in alcohol and stained by carmine then observed by microscope. The taxonomic study was carried out by measuring different parts of the body of helminthes and statistical tests were performed using the Chi-square test. A total of 27 adult and 23 juvenile stray dogs were collected and the overall prevalence rate of infection was 90%. The three most common helminthes were Toxocara canis (60%), Ancylostoma caninum (46%) and Dipylidium caninum (36%). Other parasites were Uncinaria stenocephala (12%), Taenia hydatigena (6%), Spirocerca lupi (6%), Dirofilaria immitis (6%), Toxascaris leonina (2%), Rictularia sp. (2%), Taenia ovis (2%) and Taenia taeniformis (2%). Five species of zoonotic helminthes recovered were T. canis, A. caninum, U. stenocephala, D. caninum and D. immitis. Hookworm infections (58%) were more common significantly in the young stray dogs (p < 0.01). In regard to prevalence ofA. caninum, T. canis and U. stenocephala, there was significant difference between juvenile and adult dogs (p < 0.05). The results highlight the potential role of stray dogs for transmission of helminthic parasites particularly zoonotic parasites that are a significant risk to human health.

Suppression of sun interference in the star sensor baffling stray light by total internal reflection

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Shimoji, Haruhiko; Yoshikawa, Shoji; Miyatake, Katsumasa; Hama, Kazumori; Nakamura, Shuji

2005-09-01

We have developed a star sensor as an experimental device onboard the SERVIS-1 satellite launched in October 2003. The in-orbit data have verified its fundamental performance. One of the advantages of our star sensor is that the baffle has a small length of 120 mm instead of 182 mm in the conventional two-stage baffle design. The key concepts for light shielding are total internal reflection phenomena inside a nearly half sphere (NHS) lens and scattering light control by gloss black paint. However, undesirable background noise by the sun outside of the field of view (FOV) was observed in the corner of the FOV in the orbital experiment. Ray trace simulations revealed that slight scattering light on the specular baffle wall entered the NHS lens and reached the corner of the image sensor through the multi-reflection path inside the lens. It was found that the stray light path can be shielded effectively if the diameter of the aperture under the NHS lens was reduced. We redesigned the baffle and evaluated the light shielding ability with our sun interference test facility on the ground, and confirmed that the stray light was reduced below the acceptable level. As a result, the light shielding technique which we have proposed was proved to be effective for a small-size baffle. The redesigned star sensor is planned to be installed as a main attitude sensor for the SERVIS-2 satellite scheduled to be launched in February 2008.

Preliminary evaluation of the diffraction behind the PROBA 3/ASPIICS optimized occulter

NASA Astrophysics Data System (ADS)

Baccani, Cristian; Landini, Federico; Romoli, Marco; Taccola, Matteo; Schweitzer, Hagen; Fineschi, Silvano; Bemporad, Alessandro; Loreggia, Davide; Capobianco, Gerardo; Pancrazzi, Maurizio; Focardi, Mauro; Noce, Vladimiro; Thizy, Cédric; Servaye, Jean-Sébastien; Renotte, Etienne

2016-07-01

PROBA-3 is a technological mission of the European Space Agency (ESA), devoted to the in-orbit demon- stration of formation flying (FF) techniques and technologies. ASPIICS is an externally occulted coronagraph approved by ESA as payload in the framework of the PROBA-3 mission and is currently in its C/D phase. FF offers a solution to investigate the solar corona close the solar limb using a two-component space system: the external occulter on one spacecraft and the optical instrument on the other, separated by a large distance and kept in strict alignment. ASPIICS is characterized by an inter-satellite distance of ˜144 m and an external occulter diameter of 1.42 m. The stray light due to the diffraction by the external occulter edge is always the most critical offender to a coronagraph performance: the designer work is focused on reducing the stray light and carefully evaluating the residuals. In order to match this goal, external occulters are usually characterized by an optimized shape along the optical axis. Part of the stray light evaluation process is based on the diffraction calculation with the optimized occulter and with the whole solar disk as a source. We used the field tracing software VirtualLabTM Fusion by Wyrowski Photonics [1] to simulate the diffraction. As a first approach and in order to evaluate the software, we simulated linear occulters, through as portions of the flight occulter, in order to make a direct comparison with the Phase-A measurements [2].

Observational artifacts of Nuclear Spectroscopic Telescope Array: ghost rays and stray light

NASA Astrophysics Data System (ADS)

Madsen, Kristin K.; Christensen, Finn E.; Craig, William W.; Forster, Karl W.; Grefenstette, Brian W.; Harrison, Fiona A.; Miyasaka, Hiromasa; Rana, Vikram

2017-10-01

The Nuclear Spectroscopic Telescope Array (NuSTAR) launched in June 2012, flies two conical approximation Wolter-I mirrors at the end of a 10.15-m mast. The optics are coated with multilayers of Pt/C and W/Si that operate from 3 to 80 keV. Since the optical path is not shrouded, aperture stops are used to limit the field of view (FoV) from background and sources outside the FoV. However, there is still a sliver of sky (˜1.0 deg to 4.0 deg) where photons may bypass the optics altogether and fall directly on the detector array. We term these photons stray light. Additionally, there are also photons that do not undergo the focused double reflections in the optics, and we term these ghost rays. We present detailed analysis and characterization of these two components and discuss how they impact observations. Finally, we discuss how they could have been prevented and should be in future observatories.

Quality assessment of solar UV irradiance measured with array spectroradiometers

NASA Astrophysics Data System (ADS)

Egli, Luca; Gröbner, Julian; Hülsen, Gregor; Bachmann, Luciano; Blumthaler, Mario; Dubard, Jimmy; Khazova, Marina; Kift, Richard; Hoogendijk, Kees; Serrano, Antonio; Smedley, Andrew; Vilaplana, José-Manuel

2016-04-01

The reliable quantification of ultraviolet (UV) radiation at the earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers (ASRMs) are small, light, robust and cost-effective instruments, and are increasingly used for spectral irradiance measurements. Within the European EMRP ENV03 project "Solar UV", new devices, guidelines and characterization methods have been developed to improve solar UV measurements with ASRMs, and support to the end user community has been provided. In order to assess the quality of 14 end user ASRMs, a solar UV intercomparison was held on the measurement platform of the World Radiation Center (PMOD/WRC) in Davos, Switzerland, from 10 to 17 July 2014. The results of the blind intercomparison revealed that ASRMs, currently used for solar UV measurements, show a large variation in the quality of their solar UV measurements. Most of the instruments overestimate the erythema-weighted UV index - in particular at large solar zenith angles - due to stray light contribution in the UV-B range. The spectral analysis of global solar UV irradiance further supported the finding that the uncertainties in the UV-B range are very large due to stray light contribution in this wavelength range. In summary, the UV index may be detected by some commercially available ASRMs within 5 % compared to the world reference spectroradiometer, if well characterized and calibrated, but only for a limited range of solar zenith angles. Generally, the tested instruments are not yet suitable for solar UV measurements for the entire range between 290 and 400 nm under all atmospheric conditions.

Quality assessment of solar UV irradiance measured with array spectroradiometers

NASA Astrophysics Data System (ADS)

Egli, L.; Gröbner, J.; Hülsen, G.; Bachmann, L.; Blumthaler, M.; Dubard, J.; Khazova, M.; Kift, R.; Hoogendijk, K.; Serrano, A.; Smedley, A. R. D.; Vilaplana, J.-M.

2015-12-01

The reliable quantification of ultraviolet (UV) radiation at the Earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers are small, light, robust and cost effective instruments and are increasingly used for spectral irradiance measurements. Within the European EMRP-ENV03 project "Solar UV", new devices, guidelines, and characterization methods have been developed to improve solar UV measurements with array spectroradiometers and support to the end-user community has been provided. In order to assess the quality of 14 end-user array spectroradiometers, a solar UV intercomparison was held on the measurement platform of the World Radiation Center (PMOD/WRC) in Davos, Switzerland, from 10 to 17 July 2014. The results of the intercomparison revealed that array spectroradiometers, currently used for solar UV measurements, show a large variation in the quality of their solar UV measurements. Most of the instruments overestimate the erythema weighted UV index - in particular at low solar zenith angles - due to stray light contribution in the UV-B range. The spectral analysis of global solar UV irradiance further supported the finding that the uncertainties in the UV-B range are very large due to stray light contribution in this wavelength range. In summary, the UV index may be detected by some commercially available array spectroradiometer within 5 % compared to the world reference spectroradiometer, if well characterized and calibrated, but only for a limited range or solar zenith angle. Generally, the tested instruments are not yet suitable for solar UV measurements for the entire range between 290 to 400 nm under all atmospheric conditions.

Mathematical modelling of radiotherapy strategies for early breast cancer.

PubMed

Enderling, Heiko; Anderson, Alexander R A; Chaplain, Mark A J; Munro, Alastair J; Vaidya, Jayant S

2006-07-07

Targeted intraoperative radiotherapy (Targit) is a new concept of partial breast irradiation where single fraction radiotherapy is delivered directly to the tumour bed. Apart from logistic advantages, this strategy minimizes the risk of missing the tumour bed and avoids delay between surgery and radiotherapy. It is presently being compared with the standard fractionated external beam radiotherapy (EBRT) in randomized trials. In this paper we present a mathematical model for the growth and invasion of a solid tumour into a domain of tissue (in this case breast tissue), and then a model for surgery and radiation treatment of this tumour. We use the established linear-quadratic (LQ) model to compute the survival probabilities for both tumour cells and irradiated breast tissue and then simulate the effects of conventional EBRT and Targit. True local recurrence of the tumour could arise either from stray tumour cells, or the tumour bed that harbours morphologically normal cells having a predisposition to genetic changes, such as a loss of heterozygosity (LOH) in genes that are crucial for tumourigenesis, e.g. tumour suppressor genes (TSGs). Our mathematical model predicts that the single high dose of radiotherapy delivered by Targit would result in eliminating all these sources of recurrence, whereas the fractionated EBRT would eliminate stray tumour cells, but allow (by virtue of its very schedule) the cells with LOH in TSGs or cell-cycle checkpoint genes to pass on low-dose radiation-induced DNA damage and consequently mutations that may favour the development of a new tumour. The mathematical model presented here is an initial attempt to model a biologically complex phenomenon that has until now received little attention in the literature and provides a 'proof of principle' that it is possible to produce clinically testable hypotheses on the effects of different approaches of radiotherapy for breast cancer.

Testing for Stray Current Corrosion in Earth Covered Magazines with EOP

DTIC Science & Technology

2010-02-01

potential for Stray Current Corrosion BUILDING STRONG® Plot of Current Measurements 0 0.2 0.4 0.6 0.8 1 1.2 0 10 20 30 40 50 60 70 80 90 100 % I to Rebar m...magnitude as more current was directed to the reinforcing steel.  Corrosion current was measured to the rebar probe placed above the location of...US Army Corps of Engineers BUILDING STRONG® Testing for Stray Current Corrosion in Earth Covered Magazines with EOP O. S. Marshall US Army

SIMBIOS Normalized Water-Leaving Radiance Calibration and Validation: Sensor Response, Atmospheric Corrections, Stray Light and Sun Glint. Chapter 14

NASA Technical Reports Server (NTRS)

Mueller, James L.

2001-01-01

This Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) contract supports acquisition of match up radiometric and bio-optical data for validation of Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) and other ocean color satellites, and evaluation of uncertainty budgets and protocols for in situ measurements of normalized water leaving radiances.

Beam tests of beampipe coatings for electron cloud mitigation in Fermilab Main Injector

DOE PAGES

Backfish, Michael; Eldred, Jeffrey; Tan, Cheng Yang; ...

2015-10-26

Electron cloud beam instabilities are an important consideration in virtually all high-energy particle accelerators and could pose a formidable challenge to forthcoming high-intensity accelerator upgrades. Dedicated tests have shown beampipe coatings dramatically reduce the density of electron cloud in particle accelerators. In this work, we evaluate the performance of titanium nitride, amorphous carbon, and diamond-like carbon as beampipe coatings for the mitigation of electron cloud in the Fermilab Main Injector. Altogether our tests represent 2700 ampere-hours of proton operation spanning five years. Three electron cloud detectors, retarding field analyzers, are installed in a straight section and allow a direct comparisonmore » between the electron flux in the coated and uncoated stainless steel beampipe. We characterize the electron flux as a function of intensity up to a maximum of 50 trillion protons per cycle. Each beampipe material conditions in response to electron bombardment from the electron cloud and we track the changes in these materials as a function of time and the number of absorbed electrons. Contamination from an unexpected vacuum leak revealed a potential vulnerability in the amorphous carbon beampipe coating. We measure the energy spectrum of electrons incident on the stainless steel, titanium nitride and amorphous carbon beampipes. We find the electron cloud signal is highly sensitive to stray magnetic fields and bunch-length over the Main Injector ramp cycle. In conclusion, we conduct a complete survey of the stray magnetic fields at the test station and compare the electron cloud signal to that in a field-free region.« less

Problems Associated with the Microchip Data of Stray Dogs and Cats Entering RSPCA Queensland Shelters

PubMed Central

Lancaster, Emily; Rand, Jacquie; Collecott, Sheila; Paterson, Mandy

2015-01-01

Simple Summary Microchip identification has become an important tool to reunite stray dogs and cats with their owners, and is now compulsory in most states of Australia. Improvement of the microchipping system in Australia is limited by a lack of published Australian data documenting the problems experienced by shelter staff when using microchip data to contact the owner of a stray animal. In this study we determine the character and frequency of inaccurate microchip data to identify weaknesses in the current microchipping system. This information could be used to develop strategies that increase the accuracy of microchip data that will increase the reclaiming of stray animals. Abstract A lack of published information documenting problems with the microchip data for the reclaiming of stray animals entering Australian shelters limits improvement of the current microchipping system. A retrospective study analysing admission data for stray, adult dogs (n = 7258) and cats (n = 6950) entering the Royal Society for the Prevention of Cruelty to Animals (RSPCA) Queensland between January 2012 and December 2013 was undertaken to determine the character and frequency of microchip data problems and their impact on outcome for the animal. Only 28% of dogs and 9% of cats were microchipped, and a substantial proportion (37%) had problems with their data, including being registered to a previous owner or organisation (47%), all phone numbers incorrect/disconnected (29%), and the microchip not registered (14%). A higher proportion of owners could be contacted when the microchip had no problems, compared to those with problems (dogs, 93% vs. 70%; cats, 75% vs. 41%). The proportion of animals reclaimed declined significantly between microchipped animals with no data problems, microchipped animals with data problems and non-microchipped animals—87%, 69%, and 37%, respectively, for dogs and 61%, 33%, and 5%, respectively, for cats. Strategies are needed to increase the accuracy of microchip data to facilitate the reclaiming of stray dogs and cats. PMID:26479238

Detection of Helminth Eggs and Identification of Hookworm Species in Stray Cats, Dogs and Soil from Klang Valley, Malaysia

PubMed Central

Mahmud, Rohela; Samsudin, Nur Izyan; Kek Heng, Chua; Ling, Lau Yee

2015-01-01

The present study was conducted to determine the prevalence of helminth eggs excreted in the faeces of stray cats, dogs and in soil samples. A total of 505 fresh samples of faeces (from 227 dogs and 152 cats) and soil were collected. The egg stage was detected via microscopy after the application of formalin–ether concentration technique. Genomic DNA was extracted from the samples containing hookworm eggs and used for further identification to the species level using real-time polymerase chain reaction coupled with high resolution melting analysis. Microscopic observation showed that the overall prevalence of helminth eggs among stray cats and dogs was 75.7% (95% CI = 71.2%–79.9%), in which 87.7% of dogs and 57.9% of cats were infected with at least one parasite genus. Five genera of heliminth eggs were detected in the faecal samples, including hookworms (46.4%), Toxocara (11.1%), Trichuris (8.4%), Spirometra (7.4%) and Ascaris (2.4%). The prevalence of helminth infections among stray dogs was significantly higher than that among stray cats (p < 0.001). Only three genera of helminths were detected in soil samples with the prevalence of 23% (95% CI = 15.1%–31%), consisting of hookworms (16.6%), Ascaris (4%) and Toxocara (2.4%). The molecular identification of hookworm species revealed that Ancylostoma ceylanicum was dominant in both faecal and soil samples. The dog hookworm, Ancylostoma caninum, was also detected among cats, which is the first such occurrence reported in Malaysia till date. This finding indicated that there was a cross-infection of A. caninum between stray cats and dogs because of their coexistent within human communities. Taken together, these data suggest the potential role of stray cats and dogs as being the main sources of environmental contamination as well as for human infections. PMID:26671680

Occupational exposure of healthcare and research staff to static magnetic stray fields from 1.5–7 Tesla MRI scanners is associated with reporting of transient symptoms

PubMed Central

Schaap, Kristel; Christopher-de Vries, Yvette; Mason, Catherine K; de Vocht, Frank; Portengen, Lützen; Kromhout, Hans

2014-01-01

Objectives Limited data is available about incidence of acute transient symptoms associated with occupational exposure to static magnetic stray fields from MRI scanners. We aimed to assess the incidence of these symptoms among healthcare and research staff working with MRI scanners, and their association with static magnetic field exposure. Methods We performed an observational study among 361 employees of 14 clinical and research MRI facilities in The Netherlands. Each participant completed a diary during one or more work shifts inside and/or outside the MRI facility, reporting work activities and symptoms (from a list of potentially MRI-related symptoms, complemented with unrelated symptoms) experienced during a working day. We analysed 633 diaries. Exposure categories were defined by strength and type of MRI scanner, using non-MRI shifts as the reference category for statistical analysis. Non-MRI shifts originated from MRI staff who also participated on MRI days, as well as CT radiographers who never worked with MRI. Results Varying per exposure category, symptoms were reported during 16–39% of the MRI work shifts. We observed a positive association between scanner strength and reported symptoms among healthcare and research staff working with closed-bore MRI scanners of 1.5 Tesla (T) and higher (1.5 T OR=1.88; 3.0 T OR=2.14; 7.0 T OR=4.17). This finding was mainly driven by reporting of vertigo and metallic taste. Conclusions The results suggest an exposure-response association between exposure to strong static magnetic fields (and associated motion-induced time-varying magnetic fields) and reporting of transient symptoms on the same day of exposure. Trial registration number 11-032/C PMID:24714654

43 CFR 4720.2-1 - Removal of strayed animals from private lands.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) PROTECTION, MANAGEMENT, AND CONTROL OF WILD FREE-ROAMING HORSES AND BURROS Removal § 4720.2-1 Removal of strayed animals from private...

43 CFR 4720.2-1 - Removal of strayed animals from private lands.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) PROTECTION, MANAGEMENT, AND CONTROL OF WILD FREE-ROAMING HORSES AND BURROS Removal § 4720.2-1 Removal of strayed animals from private...

43 CFR 4720.2-1 - Removal of strayed animals from private lands.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) PROTECTION, MANAGEMENT, AND CONTROL OF WILD FREE-ROAMING HORSES AND BURROS Removal § 4720.2-1 Removal of strayed animals from private...

43 CFR 4720.2 - Removal of strayed or excess animals from private lands.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) PROTECTION, MANAGEMENT, AND CONTROL OF WILD FREE-ROAMING HORSES AND BURROS Removal § 4720.2 Removal of strayed or excess...

43 CFR 4720.2 - Removal of strayed or excess animals from private lands.

Code of Federal Regulations, 2012 CFR

2012-10-01

... (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) PROTECTION, MANAGEMENT, AND CONTROL OF WILD FREE-ROAMING HORSES AND BURROS Removal § 4720.2 Removal of strayed or excess...

43 CFR 4720.2-1 - Removal of strayed animals from private lands.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) PROTECTION, MANAGEMENT, AND CONTROL OF WILD FREE-ROAMING HORSES AND BURROS Removal § 4720.2-1 Removal of strayed animals from private...

43 CFR 4720.2 - Removal of strayed or excess animals from private lands.

Code of Federal Regulations, 2013 CFR

2013-10-01

... (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) PROTECTION, MANAGEMENT, AND CONTROL OF WILD FREE-ROAMING HORSES AND BURROS Removal § 4720.2 Removal of strayed or excess...

43 CFR 4720.2 - Removal of strayed or excess animals from private lands.

Code of Federal Regulations, 2014 CFR

2014-10-01

... (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) PROTECTION, MANAGEMENT, AND CONTROL OF WILD FREE-ROAMING HORSES AND BURROS Removal § 4720.2 Removal of strayed or excess...

Effective suppression of stray light in rotational coherent anti-stokes Raman spectroscopy using an angle-tuned short-wave-pass filter.

PubMed

Bohlin, Alexis; Bengtsson, Per-Erik

2010-08-01

Stray light interference is a common problem in spontaneous rotational Raman spectroscopy and rotational coherent anti-Stokes Raman spectropscopy (CARS). The reason is that the detected spectrum appears in the spectral vicinity of the probe beam wavelength, and stray light at this wavelength from optics and surfaces is hard to suppress. In this Note, efficient suppression of stray light is demonstrated for rotational CARS measurements using a commercially available short-wave-pass filter. By angle-tuning this filter with a specified cut-off wavelength at 561 nm, the cut-off wavelength could be tuned to a desired spectral position so that more than 80% transmission is achieved as close as 15 cm(-1) (approximately 0.4 nm) from the probe beam wavelength of 532.0 nm, while the intensity at this wavelength is suppressed by two orders of magnitude.

The structure of galactic HI in directions of low total column density

NASA Technical Reports Server (NTRS)

Lockman, F. J.; Jahoda, K.; Mccammon, D.

1985-01-01

A detailed 21 cm study of areas of that have the smallest known amount of HI in the northern sky was performed. These observations were corrected for stray radiation. The region of main interest, around alpha = 10(h)45(m), delta = 57 deg 20', has a minimium N(HI) of 4.5 x 10 to the 19th power/sq cm. Spectra taken at 21' resolution over a field 4 x 3 deg in this direction show up to four HI line components. Two, near 0 and -50 km/s, are ubiquitous. There is also a narrow component at -10 km/s attributable to a diffuse cloud covering half of the field, and scattered patches of HI at v -100 km/s. the low and intermediate velocity components have a broad line width and are so smoothly distributed across the region that it is unlikely that they contain significant unresolved angular structure. Eight other low column density directions were also observed. Their spectra typically have several components, but the total column density is always 7 x 10 to the 19th power/sq cm and changes smoothly along a 2 deg strip. Half of the directions show narrow lines arising from weak diffuse HI clouds that contain 0.5 to 3.0 x 10 to the 19th power/sq cm.

Cat admissions to RSPCA shelters in Queensland, Australia: description of cats and risk factors for euthanasia after entry.

PubMed

Alberthsen, C; Rand, J S; Bennett, P C; Paterson, M; Lawrie, M; Morton, J M

2013-01-01

A lack of information limits understanding of the excess cat problem and development of effective management strategies. This study describes cats entering Royal Society for the Prevention of Cruelty to Animals (RSPCA) Queensland shelters and identifies risk factors for euthanasia. Data for cats entering relevant shelters (July 2006-June 2008) were obtained from the RSPCA's electronic database. Univariable and multivariable logistic regression analyses were conducted to identify risk factors for euthanasia. Of 33,736 cats admitted, 46% were adult cats (≥3 months) and 54% were kittens (<3 months). The most common reason for admission was stray (54%), followed by owner surrender (44%). Euthanasia was the most common outcome (65%), followed by adoption (30%). The odds of euthanasia were lower for kittens and for cats that were desexed prior to admission. Of the strays, 8% had been desexed. For cats of similar age, sex, desexed and feral status, stray cats were more likely to be adopted than owner-surrenders. Strategies are needed to reduce numbers of cats admitted and euthanased. Given the high proportion of admissions that were kittens, reducing the incidence of delayed sterilisation of owned cats may be an important strategy for reducing the number of unwanted kittens. Many cats admitted as strays were rehomable, but given the high proportion of admissions that are strays, further research on stray populations is needed. Future studies of cats entering shelters would be enhanced if data collection definitions, categories and methods were standardised. © 2013 The Authors. Australian Veterinary Journal © 2013 Australian Veterinary Association.

Design, simulation and experimental analysis of an anti-stray-light illumination system of fundus camera

NASA Astrophysics Data System (ADS)

Ma, Chen; Cheng, Dewen; Xu, Chen; Wang, Yongtian

2014-11-01

Fundus camera is a complex optical system for retinal photography, involving illumination and imaging of the retina. Stray light is one of the most significant problems of fundus camera because the retina is so minimally reflective that back reflections from the cornea and any other optical surface are likely to be significantly greater than the light reflected from the retina. To provide maximum illumination to the retina while eliminating back reflections, a novel design of illumination system used in portable fundus camera is proposed. Internal illumination, in which eyepiece is shared by both the illumination system and the imaging system but the condenser and the objective are separated by a beam splitter, is adopted for its high efficiency. To eliminate the strong stray light caused by corneal center and make full use of light energy, the annular stop in conventional illumination systems is replaced by a fiber-coupled, ring-shaped light source that forms an annular beam. Parameters including size and divergence angle of the light source are specially designed. To weaken the stray light, a polarized light source is used, and an analyzer plate is placed after beam splitter in the imaging system. Simulation results show that the illumination uniformity at the fundus exceeds 90%, and the stray light is within 1%. Finally, a proof-of-concept prototype is developed and retinal photos of an ophthalmophantom are captured. The experimental results show that ghost images and stray light have been greatly reduced to a level that professional diagnostic will not be interfered with.

Stray light calibration of the Dawn Framing Camera

NASA Astrophysics Data System (ADS)

Kovacs, Gabor; Sierks, Holger; Nathues, Andreas; Richards, Michael; Gutierrez-Marques, Pablo

2013-10-01

Sensitive imaging systems with high dynamic range onboard spacecrafts are susceptible to ghost and stray-light effects. During the design phase, the Dawn Framing Camera was laid out and optimized to minimize those unwanted, parasitic effects. However, the requirement of low distortion to the optical design and use of a front-lit focal plane array induced an additional stray light component. This paper presents the ground-based and in-flight procedures characterizing the stray-light artifacts. The in-flight test used the Sun as the stray light source, at different angles of incidence. The spacecraft was commanded to point predefined solar elongation positions, and long exposure images were recorded. The PSNIT function was calculated by the known illumination and the ground based calibration information. In the ground based calibration, several extended and point sources were used with long exposure times in dedicated imaging setups. The tests revealed that the major contribution to the stray light is coming from the ghost reflections between the focal plan array and the band pass interference filters. Various laboratory experiments and computer modeling simulations were carried out to quantify the amount of this effect, including the analysis of the diffractive reflection pattern generated by the imaging sensor. The accurate characterization of the detector reflection pattern is the key to successfully predict the intensity distribution of the ghost image. Based on the results, and the properties of the optical system, a novel correction method is applied in the image processing pipeline. The effect of this correction procedure is also demonstrated with the first images of asteroid Vesta.

Thermal analysis of the in-vessel components of the ITER plasma-position reflectometry.

PubMed

Quental, P B; Policarpo, H; Luís, R; Varela, P

2016-11-01

The ITER plasma position reflectometry system measures the edge electron density profile of the plasma, providing real-time supplementary contribution to the magnetic measurements of the plasma-wall distance. Some of the system components will be in direct sight of the plasma and therefore subject to plasma and stray radiation, which may cause excessive temperatures and stresses. In this work, thermal finite element analysis of the antenna and adjacent waveguides is conducted with ANSYS V17 (ANSYS® Academic Research, Release 17.0, 2016). Results allow the identification of critical temperature points, and solutions are proposed to improve the thermal behavior of the system.

Thermal analysis of the in-vessel components of the ITER plasma-position reflectometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quental, P. B., E-mail: pquental@ipfn.tecnico.ulisboa.pt; Policarpo, H.; Luís, R.

The ITER plasma position reflectometry system measures the edge electron density profile of the plasma, providing real-time supplementary contribution to the magnetic measurements of the plasma-wall distance. Some of the system components will be in direct sight of the plasma and therefore subject to plasma and stray radiation, which may cause excessive temperatures and stresses. In this work, thermal finite element analysis of the antenna and adjacent waveguides is conducted with ANSYS V17 (ANSYS® Academic Research, Release 17.0, 2016). Results allow the identification of critical temperature points, and solutions are proposed to improve the thermal behavior of the system.

Gastrointestinal parasites in stray and shelter cats in the municipality of Rio de Janeiro, Brazil.

PubMed

Pereira, Pâmela Figueiredo; Barbosa, Alynne da Silva; Moura, Ana Paula Pereira de; Vasconcellos, Marcelo Leitão; Uchôa, Claudia Maria Antunes; Bastos, Otílio Machado Pereira; Amendoeira, Maria Regina Reis

2017-01-01

The increasingly urban nature of the population has led many people to choose independent pets, such as cats. This situation has also made it possible for these animals to be abandoned, thus increasing the numbers of cats on the streets and in shelters. These animals can act as a source of infection for other hosts. Between 2014 and 2015, the frequency of gastrointestinal parasites in captive and stray cats in the municipality of Rio de Janeiro was analyzed. Ninety-one fecal samples were collected from captive cats and 172 from stray cats. Centrifugal sedimentation and flotation techniques were used. The frequency of parasites among the stray cats was 77.3%, and this was significantly higher than the frequency observed in captive cats (49.5%). Helminths were detected more frequently, and hookworms were the parasites most detected. Toxocara cati, Cystoisospora sp. and Dipylidium caninum were also detected. No statistical difference in the frequency of parasites was observed between the sexes among the captive cats. However, among the stray cats, males (85.5%) presented higher positivity than females (71.8%). The high frequency of hookworms, which are the agent for "cutaneous larva migrans" in humans, shows the need to control parasitic infections among the cats studied.

Assessment of a Targeted Trap-Neuter-Return Pilot Study in Auckland, New Zealand.

PubMed

Zito, Sarah; Aguilar, Glenn; Vigeant, Shalsee; Dale, Arnja

2018-05-13

There is a need for effective and humane management tools to manage urban stray cats and minimise negative impacts associated with stray cats. One such tool is targeted trap-neuter-return (TTNR), but no concerted implementation of this technique or formal assessments have been reported. To address this deficit, a TTNR programme was implemented and assessed in one Auckland suburb from May 2015 to June 2016; the programme sterilised and returned 348 cats (4.2 cats/1000 residents). Assessment was based on the number of incoming felines; stray, unsocialised cats euthanased; unsocialised, unowned cats sterilised and returned (independently of the TTNR programme); and neonatal/underage euthanasias. Incoming stray felines, underage euthanasias, and unsocialised stray cat euthanasias were all reduced for the targeted suburb when compared for the years before and after the programme (the percentage reduction in these parameters was −39, −17, −34, −7, and −47, respectively). These outcome measures had a greater reduction in the targeted suburb compared to the Auckland suburbs not targeted by the TTNR programme ( p < 0.01), although causation cannot be inferred, as a variety of reasons could have contributed to the changes. This pilot programme suggests that TTNR could be a valuable, humane cat management tool in urban New Zealand, and further assessment is warranted.

Mobile machine hazardous working zone warning system

DOEpatents

Schiffbauer, William H.; Ganoe, Carl W.

1999-01-01

A warning system is provided for a mobile working machine to alert an individual of a potentially dangerous condition in the event the individual strays into a hazardous working zone of the machine. The warning system includes a transmitter mounted on the machine and operable to generate a uniform magnetic field projecting beyond an outer periphery of the machine in defining a hazardous working zone around the machine during operation thereof. A receiver, carried by the individual and activated by the magnetic field, provides an alarm signal to alert the individual when he enters the hazardous working zone of the machine.

Mobile machine hazardous working zone warning system

DOEpatents

Schiffbauer, W.H.; Ganoe, C.W.

1999-08-17

A warning system is provided for a mobile working machine to alert an individual of a potentially dangerous condition in the event the individual strays into a hazardous working zone of the machine. The warning system includes a transmitter mounted on the machine and operable to generate a uniform magnetic field projecting beyond an outer periphery of the machine in defining a hazardous working zone around the machine during operation. A receiver, carried by the individual and activated by the magnetic field, provides an alarm signal to alert the individual when he enters the hazardous working zone of the machine. 3 figs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Vinita J.; Schaefer, Charles; Kahnhauser, Henry

The National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory was shut down in September 2014. Lead bricks used as radiological shadow shielding within the accelerator were exposed to stray radiation fields during normal operations. The FLUKA code, a fully integrated Monte Carlo simulation package for the interaction and transport of particles and nuclei in matter, was used to estimate induced radioactivity in this shielding and stainless steel beam pipe from known beam losses. The FLUKA output was processed using MICROSHIELD® to estimate on-contact exposure rates with individually exposed bricks to help design and optimize the radiological survey process. Thismore » entire process can be modeled using FLUKA, but use of MICROSHIELD® as a secondary method was chosen because of the project’s resource constraints. Due to the compressed schedule and lack of shielding configuration data, simple FLUKA models were developed in this paper. FLUKA activity estimates for stainless steel were compared with sampling data to validate results, which show that simple FLUKA models and irradiation geometries can be used to predict radioactivity inventories accurately in exposed materials. During decommissioning 0.1% of the lead bricks were found to have measurable levels of induced radioactivity. Finally, post-processing with MICROSHIELD® provides an acceptable secondary method of estimating residual exposure rates.« less

Anti-glare LED lamps with adjustable illumination light field.

PubMed

Chen, Yung-Sheng; Lin, Chung-Yi; Yeh, Chun-Ming; Kuo, Chie-Tong; Hsu, Chih-Wei; Wang, Hsiang-Chen

2014-03-10

We introduce a type of LED light-gauge steel frame lamp with an adjustable illumination light field that does not require a diffusion plate. Base on the Monte Carlo ray tracing method, this lamp has a good glare rating (GR) of 17.5 at 3050 lm. Compared with the traditional LED light-gauge steel frame lamp (without diffusion plate), the new type has low GR. The adjustability of the illumination light field could improve the zebra effect caused by the inadequate illumination light field of the lamp. Meanwhile, we adopt the retinal image analysis to discuss the influence of GR on vision. High GR could reflect stray light on the retinal image, which will reduce vision clarity and hasten the feeling of eye fatigue.

Magnetic profiling of the San Andreas Fault using a dual magnetometer UAV aerial survey system.

NASA Astrophysics Data System (ADS)

Abbate, J. A.; Angelopoulos, V.; Masongsong, E. V.; Yang, J.; Medina, H. R.; Moon, S.; Davis, P. M.

2017-12-01

Aeromagnetic survey methods using planes are more time-effective than hand-held methods, but can be far more expensive per unit area unless large areas are covered. The availability of low cost UAVs and low cost, lightweight fluxgate magnetometers (FGMs) allows, with proper offset determination and stray fields correction, for low-cost magnetic surveys. Towards that end, we have developed a custom multicopter UAV for magnetic mapping using a dual 3-axis fluxgate magnetometer system: the GEOphysical Drone Enhanced Survey Instrument (GEODESI). A high precision sensor measures the UAV's position and attitude (roll, pitch, and yaw) and is recorded using a custom Arduino data processing system. The two FGMs (in-board and out-board) are placed on two ends of a vertical 1m boom attached to the base of the UAV. The in-board FGM is most sensitive to stray fields from the UAV and its signal is used, after scaling, to clean the signal of the out-board FGM from the vehicle noise. The FGMs record three orthogonal components of the magnetic field in the UAV body coordinates which are then transformed into a north-east-down coordinate system using a rotation matrix determined from the roll-pitch-yaw attitude data. This ensures knowledge of the direction of all three field components enabling us to perform inverse modeling of magnetic anomalies with greater accuracy than total or vertical field measurements used in the past. Field tests were performed at Dragon's Back Pressure Ridge in the Carrizo Plain of California, where there is a known crossing of the San Andreas Fault. Our data and models were compared to previously acquired LiDAR and hand-held magnetometer measurements. Further tests will be carried out to solidify our results and streamline our processing for educational use in the classroom and student field training.

Stray Current Corrosion in Electrified Rail Systems - Final Report

DOT National Transportation Integrated Search

1995-05-01

The objectives of this study were (1)to assess the scope of stray-current corrosion on electrified rail systems based upon information in the literature and from interviews with selected transit system operators, and (2)to determine whether new or ad...

Control of vortex state in cobalt nanorings with domain wall pinning centers

NASA Astrophysics Data System (ADS)

Lal, Manohar; Sakshath, S.; Mohanan Parakkat, Vineeth; Anil Kumar, P. S.

2018-05-01

Magnetic rings at the mesoscopic scale exhibit new spin configuration states and switching behavior, which can be controlled via geometrical structure, material composition and applied field. Vortex states in magnetic nanorings ensure flux closure, which is necessary for low stray fields in high packing density in memory devices. We performed magnetoresistance measurements on cobalt nanoring devices and show that by attaching nanowires to the ring, the vortex state can be stabilized. When a square pad is attached to the free end of the wire, the domain wall nucleation field in the nanowire is reduced. In addition, the vortex state persists over a larger range of magnetic fields, and exists at all in-plane orientations of the magnetic field. These experimental findings are well supported by our micromagnetic simulations.

Improved SOT (Hinode mission) high resolution solar imaging observations

NASA Astrophysics Data System (ADS)

Goodarzi, H.; Koutchmy, S.; Adjabshirizadeh, A.

2015-08-01

We consider the best today available observations of the Sun free of turbulent Earth atmospheric effects, taken with the Solar Optical Telescope (SOT) onboard the Hinode spacecraft. Both the instrumental smearing and the observed stray light are analyzed in order to improve the resolution. The Point Spread Function (PSF) corresponding to the blue continuum Broadband Filter Imager (BFI) near 450 nm is deduced by analyzing (i) the limb of the Sun and (ii) images taken during the transit of the planet Venus in 2012. A combination of Gaussian and Lorentzian functions is selected to construct a PSF in order to remove both smearing due to the instrumental diffraction effects (PSF core) and the large-angle stray light due to the spiders and central obscuration (wings of the PSF) that are responsible for the parasitic stray light. A Max-likelihood deconvolution procedure based on an optimum number of iterations is discussed. It is applied to several solar field images, including the granulation near the limb. The normal non-magnetic granulation is compared to the abnormal granulation which we call magnetic. A new feature appearing for the first time at the extreme- limb of the disk (the last 100 km) is discussed in the context of the definition of the solar edge and of the solar diameter. A single sunspot is considered in order to illustrate how effectively the restoration works on the sunspot core. A set of 125 consecutive deconvolved images is assembled in a 45 min long movie illustrating the complexity of the dynamical behavior inside and around the sunspot.

Prevalence of filarial parasites in domestic and stray cats in Selangor State, Malaysia.

PubMed

Al-Abd, Nazeh M; Nor, Zurainee Mohamed; Kassim, Mustafa; Mansor, Marzida; Al-Adhroey, Abdulelah H; Ngui, Romano; Sivanandam, Sinnadurai

2015-09-01

To determine the prevalence of the filarial parasites,ie.,Brugia malayi, Brugia, Brugia pahangi(B. pahangi), Dirofilaria immitisandDirofilaria repens (D. repens) in domestic and stray cats. A total of 170 blood sample were collected from domestic and stray cats and examined for filarial worm parasites in two localities, Pulau Carey and Bukit Gasing, Selangor State, Malaysia. The overall prevalence of infection was 23.5% (40/170; 95% CI = 17.4-30.6). Of this, 35% (14/40; 95% CI = 22.1-50.5) and 50% (20/40; 95% CI = 35.2-64.8) were positive for single B. pahangi nd D. repens, respectively. The remaining of 15% (6/40; 95% CI = 7.1-29.1) were positive for mixed B. pahangi and D. repens. In addition, 75% of the infected cats were domestic, and 25% were strays. No Brugia malayi and Dirofilaria immitis was detected. Eighty-four cats were captured at Pulau Carey, of which 35.7% (30/84) were infected. Among the cats determined to be infected, 93% (28/30; 95% CI = 78.7-98.2) were domestic, and only 6.7% (2/30; 95% CI = 19.0-21.3) were strays. Conversely, the number of infected cats was three times lower in Bukit Gasing than in Pulau Carey, and most of the cats were stray. B. pahangi and D. repens could be the major parasites underlying filariasis in the study area. Adequate prophylactic plans should be administrated in the cat population in study area. Copyright © 2015 Hainan Medical College. Production and hosting by Elsevier B.V. All rights reserved.

Probes for measuring noise current in an electronic cable

NASA Technical Reports Server (NTRS)

Lundy, C. C.

1974-01-01

Electromagnetic interference in deep-space network receiver is often caused by stray coupling from power lines. These stray signals create potential differences between ground terminals, which leads to excessive noise in receiver circuits. Pair of probes detect and measure noise currents in conductors.

First genetic characterization of Toxoplasma gondii in stray cats from Algeria.

PubMed

Yekkour, Feriel; Aubert, Dominique; Mercier, Aurélien; Murat, Jean-Benjamin; Khames, Mammar; Nguewa, Paul; Ait-Oudhia, Khatima; Villena, Isabelle; Bouchene, Zahida

2017-05-30

Toxoplasmosis is a parasitic disease with worldwide distribution and a major public health problem. In Algeria, no data are currently available about genotypes of Toxoplasma gondii isolated from animals or humans. The present study assesses for the first time the seroprevalence of toxoplasmosis in stray cats, and provides molecular characterization of T. gondii strains circulating in this feline population in Algiers, the capital city of Algeria. Sera from 96 stray cats were tested for the presence of antibodies against T. gondii using the modified agglutination test. The seroprevalence was 50% (48/96) using 1:6 as the positivity cut-off. Different organs samples from stray cats, including heart samples, were tested for the presence of Toxoplasma DNA using real-time PCR. T. Gondii DNA was detected in 90.6% (87/96) of hearts. Of these parasitic DNAs, 22 were submitted to genotyping through the analysis of 15 microsatellite markers. The identified genotypes (12 of 22) mainly belonged to the type II lineage. Copyright © 2017 Elsevier B.V. All rights reserved.

White Light Stray Light Test of the SOHO UVCS

NASA Technical Reports Server (NTRS)

Gardner, L. N.; Gardner, L. N.; Fineschi, S.

1998-01-01

During the late stages of the integration phase of the Ultraviolet Coronagraph Spectrometer (UVCS) instrument for the Solar and Heliospheric Observatory (SOHO) at MATRA-Marconi in Toulouse, France, SOHO Project management at Goddard Space Flight Center (GSFC) became concerned that the elaborate stray light rejection system for the instrument had not been tested and might possibly be misaligned such that the instrument could not deliver promised scientific returns. A white light stray light test, which would place an upper bound on the value of UVCS's stray light rejection capability, was commissioned, conceived, and carried out. This upper bound value would be indicative of the weakest coronal features the spectrometer would be capable of discerning. The test was rapidly developed at GSFC in coordination with science team members from Harvard-Smithsonian Center for Astrophysics (CFA) and was carried out at MATRA in late February 1995. The outcome of this test helped to justify similar, much desired tests with visible and far ultraviolet light at CFA in a facility specifically designed to perform such testing.

Radiation Durability of Candidate Polymer Films for the Next Generation Space Telescope Sunshield

NASA Technical Reports Server (NTRS)

Dever, Joyce; Semmel, Charles; Edwards, David; Messer, Russell; Peters, Wanda; Carter, Amani; Puckett, David

2002-01-01

The Next Generation Space Telescope (NGST), anticipated to be launched in 2009 for a 10-year mission, will make observations in the infrared portion of the spectrum to examine the origins and evolution of our universe. Because it must operate at cold temperatures in order to make these sensitive measurements, it will use a large, lightweight, deployable sunshield, comprised of several polymer film layers, to block heat and stray light. This paper describes laboratory radiation durability testing of candidate NGST sunshield polymer film materials. Samples of fluorinated polyimides CP1 and CP2, and a polvarylene ether benzimidazole. TOR-LM(TM), were exposed to 40 keV electron and 40 keV proton radiation followed by exposure to vacuum ultraviolet (VUV) radiation in the 115 to 200 nm wavelength range. Samples of these materials were also exposed to VUV without prior electron and proton exposure. Samples of polyimides Kapton HN, Kapton E, and Upilex-S were exposed to electrons and protons only, due to limited available exposure area in the VUV facility. Exposed samples were evaluated for changes in solar absorptance and thermal emittance and mechanical properties of ultimate tensile strength and elongation at failure. Data obtained are compared with previously published data for radiation durability testing of these polymer film materials.

Measurement of optical coupling between adjacent bi-material microcantilevers.

PubMed

Canetta, Carlo; Narayanaswamy, Arvind

2013-10-01

Low thermal conductance bi-material microcantilevers are fabricated with a pad area near the free end to accommodate a focused laser spot. A pair of such cantilevers are proposed as a configuration for measuring thermal conductance of a nanostructure suspended between the two. We determine the resolution of such a device by measuring the stray conductance it would detect in the absence of any nanostructure. Stray conductance, primarily due to optical coupling, is measured for cantilevers with varying pad size and found to be as low as 0.05 nW K(-1), with cantilevers with larger pad size yielding the smallest stray conductance.

Zoonotic Parasites of Sheltered and Stray Dogs in the Era of the Global Economic and Political Crisis.

PubMed

Otranto, Domenico; Dantas-Torres, Filipe; Mihalca, Andrei D; Traub, Rebecca J; Lappin, Michael; Baneth, Gad

2017-10-01

Sheltered and stray dogs, exposed to zoonotic parasites, including protozoa, helminths, and arthropods, may represent a major threat to public health. Resources for addressing health problems in these animals are not on the priority list of veterinary and public health authorities. Thus, dogs continue to represent an important reservoir for zoonotic parasites. In this article, we review the importance of sheltered and stray dogs as reservoirs of zoonotic parasites in different parts of the world, especially in the context of the current global political and economic crisis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Astrometric Calibration and Performance of the Dark Energy Camera

DOE PAGES

Bernstein, G. M.; Armstrong, R.; Plazas, A. A.; ...

2017-05-30

We characterize the ability of the Dark Energy Camera (DECam) to perform relative astrometry across its 500 Mpix, 3more » $deg^2$ science field of view, and across 4 years of operation. This is done using internal comparisons of $~ 4 x 10^7$ measurements of high-S/N stellar images obtained in repeat visits to fields of moderate stellar density, with the telescope dithered to move the sources around the array. An empirical astrometric model includes terms for: optical distortions; stray electric fields in the CCD detectors; chromatic terms in the instrumental and atmospheric optics; shifts in CCD relative positions of up to $$\\approx 10 \\mu m$$ when the DECam temperature cycles; and low-order distortions to each exposure from changes in atmospheric refraction and telescope alignment. Errors in this astrometric model are dominated by stochastic variations with typical amplitudes of 10-30 mas (in a 30 s exposure) and $$5^{\\prime}-10^{\\prime}$$ arcmin coherence length, plausibly attributed to Kolmogorov-spectrum atmospheric turbulence. The size of these atmospheric distortions is not closely related to the seeing. Given an astrometric reference catalog at density $$\\approx 0.7$$ $$arcmin^{-2}$$, e.g. from Gaia, the typical atmospheric distortions can be interpolated to $$\\approx$$ 7 mas RMS accuracy (for 30 s exposures) with $$1^{\\prime}$$ arcmin coherence length for residual errors. Remaining detectable error contributors are 2-4 mas RMS from unmodelled stray electric fields in the devices, and another 2-4 mas RMS from focal plane shifts between camera thermal cycles. Thus the astrometric solution for a single DECam exposure is accurate to 3-6 mas ( $$\\approx$$ 0.02 pixels, or $$\\approx$$ 300 nm) on the focal plane, plus the stochastic atmospheric distortion.« less

The spatially resolved characterisation of Egyptian blue, Han blue and Han purple by photo-induced luminescence digital imaging.

PubMed

Verri, G

2009-06-01

The photo-induced luminescence properties of Egyptian blue, Han blue and Han purple were investigated by means of near-infrared digital imaging. These pigments emit infrared radiation when excited in the visible range. The emission can be recorded by means of a modified commercial digital camera equipped with suitable glass filters. A variety of visible light sources were investigated to test their ability to excite luminescence in the pigments. Light-emitting diodes, which do not emit stray infrared radiation, proved an excellent source for the excitation of luminescence in all three compounds. In general, the use of visible radiation emitters with low emission in the infrared range allowed the presence of the pigments to be determined and their distribution to be spatially resolved. This qualitative imaging technique can be easily applied in situ for a rapid characterisation of materials. The results were compared to those for Egyptian green and for historical and modern blue pigments. Examples of the application of the technique on polychrome works of art are presented.

An empirical comparison of primary baffle and vanes for optical astronomical telescope

NASA Astrophysics Data System (ADS)

Li, Taoran; Chen, Yingwei

2017-09-01

In optical astronomical telescopes, the primary baffle is a tube-like structure centering in the hole of the primary mirror and the vanes usually locate inside the baffle, improving the suppression of stray light. They are the most common methods of stray light control. To characterize the performance of primary baffle and vanes, an empirical comparison based on astronomical observations has been made with Xinglong 50cm telescope. Considering the convenience of switching, an independent vanes structure is designed, which can also improve the process of the primary mirror cooling and the air circulation. The comparison of two cases: (1) primary baffle plus vanes and (2) vanes alone involves in-dome and on-sky observations. Both the single star and the various off-axis angles of the stray light source observations are presented. The photometrical images are recorded by CCD to analyze the magnitude and the photometric error. The stray light uniformity of the image background derives from the reduction image which utilizes the MATLAB software to remove the stars. The in-dome experiments results reveal the effectiveness of primary baffle and the independent vanes structure. Meanwhile, the on-sky photometric data indicate there are little differences between them. The stray light uniformity has no difference when the angle between the star and the moon is greater than 20 degrees.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, S. A.; Plummer, G.; Fedor, J.

Mapping the distribution of currents inside a superconductor is usually performed indirectly through imaging of the stray magnetic fields above the surface. Here, we show that by direct imaging of the Doppler shift contribution to the quasiparticle excitation spectrum in the superconductor using low temperature scanning tunneling microscopy, we obtain directly the distribution of supercurrents inside the superconductor. We demonstrate the technique at the example of superconductor/ferromagnet hybrid structure that produces intricate current pattern consisting of combination Meissner shielding currents and Abrikosov vortex currents.

Theory and Implementation of a VLSI Stray Insensitive Switched Capacitor Composite Operational Amplifier

DTIC Science & Technology

1994-06-01

to the simulations, we get a proof of correct concept that matches the mathematical foundation of the microchip. 108 Vill. APPLICATIONS A. WHERE AND...ORGANIZATION (if applicable ) 8c. ADDRESS (City, State, and ZIP Code) 10. SOURCE OF FUNDING NUMBERS Ivogru Elewwn No. Pro8a No. Task No. Wor Unit Acess L...necessary and identify by block number) ’ FIELD GROUP SUBGROUP Mathematical derivation of circuit transfer functions, Composite Operational Amplifiers

Energy Harvesting from the Stray Electromagnetic Field around the Electrical Power Cable for Smart Grid Applications

PubMed Central

2016-01-01

For wireless sensor node (WSN) applications, this paper presents the harvesting of energy from the stray electromagnetic field around an electrical power line. Inductive and capacitive types of electrodynamic energy harvesters are developed and reported. For the produced energy harvesters, solid core and split-core designs are adopted. The inductive energy harvester comprises a copper wound coil which is produced on a mild steel core. However, the capacitive prototypes comprise parallel, annular discs separated by Teflon spacers. Moreover, for the inductive energy harvesters' wound coil and core, the parametric analysis is also performed. A Teflon housing is incorporated to protect the energy harvester prototypes from the harsh environmental conditions. Among the inductive energy harvesters, prototype-5 has performed better than the other harvesters and produces a maximum rms voltage of 908 mV at the current level of 155 A in the power line. However, at the same current flow, the capacitive energy harvesters produce a maximum rms voltage of 180 mV. The alternating output of the prototype-5 is rectified, and a super capacitor (1 F, 5.5 V) and rechargeable battery (Nickel-Cadmium, 3.8 V) are charged with it. Moreover, with the utilization of a prototype-5, a self-powered wireless temperature sensing and monitoring system for an electrical transformer is also developed and successfully implemented. PMID:27579343

HMI Data Corrected for Stray Light Now Available

NASA Astrophysics Data System (ADS)

Norton, A. A.; Duvall, T. L.; Schou, J.; Cheung, M. C. M.; Scherrer, P. H.

2016-10-01

The form of the point spread function (PSF) derived for HMI is an Airy function convolved with a Lorentzian. The parameters are bound by observational ground-based testing of the instrument conducted prior to launch (Wachter et al., 2012), by full-disk data used to evaluate the off-limb behavior of the scattered light, as well as by data obtained during the Venus transit. The PSF correction has been programmed in both C and cuda C and runs within the JSOC environment using either a CPU or GPU. A single full-disk intensity image can be deconvolved in less than one second. The PSF is described in more detail in Couvidat et al. (2016) and has already been used by Hathaway et al. (2015) to forward-model solar-convection spectra, by Krucker et al. (2015) to investigate footpoints of off-limb solar flares and by Whitney, Criscuoli and Norton (2016) to examine the relations between intensity contrast and magnetic field strengths. In this presentation, we highlight the changes to umbral darkness, granulation contrast and plage field strengths that result from stray light correction. A twenty-four hour period of scattered-light corrected HMI data from 2010.08.03, including the isolated sunspot NOAA 11092, is currently available for anyone. Requests for additional time periods of interest are welcome and will be processed by the HMI team.

Energy Harvesting from the Stray Electromagnetic Field around the Electrical Power Cable for Smart Grid Applications.

PubMed

Khan, Farid Ullah

For wireless sensor node (WSN) applications, this paper presents the harvesting of energy from the stray electromagnetic field around an electrical power line. Inductive and capacitive types of electrodynamic energy harvesters are developed and reported. For the produced energy harvesters, solid core and split-core designs are adopted. The inductive energy harvester comprises a copper wound coil which is produced on a mild steel core. However, the capacitive prototypes comprise parallel, annular discs separated by Teflon spacers. Moreover, for the inductive energy harvesters' wound coil and core, the parametric analysis is also performed. A Teflon housing is incorporated to protect the energy harvester prototypes from the harsh environmental conditions. Among the inductive energy harvesters, prototype-5 has performed better than the other harvesters and produces a maximum rms voltage of 908 mV at the current level of 155 A in the power line. However, at the same current flow, the capacitive energy harvesters produce a maximum rms voltage of 180 mV. The alternating output of the prototype-5 is rectified, and a super capacitor (1 F, 5.5 V) and rechargeable battery (Nickel-Cadmium, 3.8 V) are charged with it. Moreover, with the utilization of a prototype-5, a self-powered wireless temperature sensing and monitoring system for an electrical transformer is also developed and successfully implemented.

Eliminating Unwanted Far-Field Excitation in Objective-Type TIRF. Part I. Identifying Sources of Nonevanescent Excitation Light

PubMed Central

Brunstein, Maia; Teremetz, Maxime; Hérault, Karine; Tourain, Christophe; Oheim, Martin

2014-01-01

Total internal reflection fluorescence microscopy (TIRFM) achieves subdiffraction axial sectioning by confining fluorophore excitation to a thin layer close to the cell/substrate boundary. However, it is often unknown how thin this light sheet actually is. Particularly in objective-type TIRFM, large deviations from the exponential intensity decay expected for pure evanescence have been reported. Nonevanescent excitation light diminishes the optical sectioning effect, reduces contrast, and renders TIRFM-image quantification uncertain. To identify the sources of this unwanted fluorescence excitation in deeper sample layers, we here combine azimuthal and polar beam scanning (spinning TIRF), atomic force microscopy, and wavefront analysis of beams passing through the objective periphery. Using a variety of intracellular fluorescent labels as well as negative staining experiments to measure cell-induced scattering, we find that azimuthal beam spinning produces TIRFM images that more accurately portray the real fluorophore distribution, but these images are still hampered by far-field excitation. Furthermore, although clearly measureable, cell-induced scattering is not the dominant source of far-field excitation light in objective-type TIRF, at least for most types of weakly scattering cells. It is the microscope illumination optical path that produces a large cell- and beam-angle invariant stray excitation that is insensitive to beam scanning. This instrument-induced glare is produced far from the sample plane, inside the microscope illumination optical path. We identify stray reflections and high-numerical aperture aberrations of the TIRF objective as one important source. This work is accompanied by a companion paper (Pt.2/2). PMID:24606927

Characterization of magnetic colloids by means of magnetooptics.

PubMed

Baraban, L; Erbe, A; Leiderer, P

2007-05-01

A new, efficient method for the characterization of magnetic colloids based on the Faraday effect is proposed. According to the main principles of this technique, it is possible to detect the stray magnetic field of the colloidal particles induced inside the magnetooptical layer. The magnetic properties of individual particles can be determined providing measurements in a wide range of magnetic fields. The magnetization curves of capped colloids and paramagnetic colloids were measured by means of the proposed approach. The registration of the magnetooptical signals from each colloidal particle in an ensemble permits the use of this technique for testing the magnetic monodispersity of colloidal suspensions.

Optimizing Hardware Compatibility for Scaling Up Superconducting Qubits

NASA Astrophysics Data System (ADS)

Fang, Michael; Campbell, Brooks; Chen, Zijun; Chiaro, Ben; Dunsworth, Andrew; Kelly, Julian; Megrant, Anthony; Neill, Charles; O'Malley, Peter; Quintana, Chris; Vainsencher, Amit; Wenner, Jim; White, Ted; Barends, Rami; Chen, Yu; Fowler, Austin; Jeffrey, Evan; Mutus, Josh; Roushan, Pedram; Sank, Daniel; Martinis, John

2015-03-01

Since quantum computation relies on the manipulation of fragile quantum states, qubit devices must be isolated from the noisy environment to prevent decoherence. Custom made components make isolation from thermal and infrared radiation possible, but have been unreliable, massive, and show sub-ideal microwave performance. Infrared isolation for large scale experiments (> 8 qubits) was achieved with compact impedance matched microwave filters which attenuate stray infrared signals on cryogenic cables with only -25 dB reflection up to 7.5 GHz. In addition, a thermal anchoring system was designed to effectively transfer unwanted heat from more than 100 coaxial cables in the dilution refrigerator and yielded a 33 percent improvement in base temperature and 50% improvement in hold time.

Design criteria of the bolometer diagnostic for steady-state operation of the W7-X stellaratora)

NASA Astrophysics Data System (ADS)

Zhang, D.; Burhenn, R.; Koenig, R.; Giannone, L.; Grodzki, P. A.; Klein, B.; Grosser, K.; Baldzuhn, J.; Ewert, K.; Erckmann, V.; Hirsch, M.; Laqua, H. P.; Oosterbeek, J. W.

2010-10-01

A bolometric diagnostic system with features necessary for steady-state operation in the superconducting stellarator W7-X was designed. During a pulse length of 1800 s with an ECRH (electron cyclotron resonance heating) power of 10 MW, the components suffer not only from a large thermal load but also from stray radiation of the nonabsorbed isotropic microwaves. This paper gives an overview of the technical problems encountered during the design work and the solutions to individual problems to meet the special requirements in W7-X, e.g., component thermal protection, detector offset thermal drift suppression, as well as a microwave shielding technique.

Evaluation of a method to shield a welding electron beam from magnetic interference

NASA Technical Reports Server (NTRS)

Wall, W. A.

1976-01-01

It is known that electron beams are easily deflected by magnetic and electrostatic fields. Therefore, to prevent weld defects, stray electromagnetic fields are avoided in electron beam welding chambers if at all possible. The successful results of tests conducted at MSFC to evaluate a simple magnetic shield made from steel tubing are reported. Tests indicate that this shield was up to 85 percent effective in reducing magnetic effects on the electron beam of a welding machine. In addition, residual magnetic fields within the shield were so nearly uniform that the net effect on the beam alignment was negligible. It is concluded that the shield, with the addition of a tungsten liner, could be used in production welding.

Nanostructure Secondary-Mirror Apodizing Mask for Transmitter Signal Suppression in a Duplex Telescope

NASA Technical Reports Server (NTRS)

Hagopian, John; Livas, Jeffrey; Shiri, Shahram; Getty, Stephanie; Tveekrem, June; Butler, James

2012-01-01

A document discusses a nanostructure apodizing mask, made of multi-walled carbon nanotubes, that is applied to the centers (or in and around the holes) of the secondary mirrors of telescopes that are used to interferometrically measure the strain of space-time in response to gravitational waves. The shape of this ultra-black mask can be adjusted to provide a smooth transition to the clear aperture of the secondary mirror to minimize diffracted light. Carbon nanotubes grown on silicon are a viable telescope mirror substrate, and can absorb significantly more light than other black treatments. The hemispherical reflectance of multi-walled carbon nanotubes grown at GSFC is approximately 3 to 10 times better than a standard aerospace paint used for stray light control. At the LISA (Laser Interferometer Space Antenna) wavelength of 1 micron, the advantage over paint is a factor of 10. Primarily, in the center of the secondary mirror (in the region of central obscuration, where no received light is lost) a black mask is applied to absorb transmitted light that could be reflected back into the receiver. In the LISA telescope, this is in the center couple of millimeters. The shape of this absorber is critical to suppress diffraction at the edge. By using the correct shape, the stray light can be reduced by approximately 10 to the 9 orders of magnitude versus no center mask. The effect of the nanotubes has been simulated in a stray-light model. The effect of the apodizing mask has been simulated in a near-field diffraction model. Specifications are geometry-dependent, but the baseline design for the LISA telescope has been modeled as well. The coatings are somewhat fragile, but work is continuing to enhance adhesion.

A Consistent EPIC Visible Channel Calibration Using VIIRS and MODIS as a Reference.

NASA Astrophysics Data System (ADS)

Haney, C.; Doelling, D. R.; Minnis, P.; Bhatt, R.; Scarino, B. R.; Gopalan, A.

2017-12-01

The Earth Polychromatic Imaging Camera (EPIC) aboard the Deep Space Climate Observatory (DSCOVR) satellite constantly images the sunlit disk of Earth from the Lagrange-1 (L1) point in 10 spectral channels spanning the UV, VIS, and NIR spectrums. Recently, the DSCOVR EPIC team has publicly released version 2 dataset, which has implemented improved navigation, stray-light correction, and flat-fielding of the CCD array. The EPIC 2-year data record must be well-calibrated for consistent cloud, aerosol, trace gas, land use and other retrievals. Because EPIC lacks onboard calibrators, the observations made by EPIC channels must be calibrated vicariously using the coincident measurements from radiometrically stable instruments that have onboard calibration systems. MODIS and VIIRS are best-suited instruments for this task as they contain similar spectral bands that are well-calibrated onboard using solar diffusers and lunar tracking. We have previously calibrated the EPIC version 1 dataset by using EPIC and VIIRS angularly matched radiance pairs over both all-sky ocean and deep convective clouds (DCC). We noted that the EPIC image required navigations adjustments, and that the EPIC stray-light correction provided an offset term closer to zero based on the linear regression of the EPIC and VIIRS ray-matched radiance pairs. We will evaluate the EPIC version 2 navigation and stray-light improvements using the same techniques. In addition, we will monitor the EPIC channel calibration over the two years for any temporal degradation or anomalous behavior. These two calibration methods will be further validated using desert and DCC invariant Earth targets. The radiometric characterization of the selected invariant targets is performed using multiple years of MODIS and VIIRS measurements. Results of these studies will be shown at the conference.

A Consistent EPIC Visible Channel Calibration using VIIRS and MODIS as a Reference

NASA Technical Reports Server (NTRS)

Haney, C. O.; Doelling, D. R.; Minnis, P.; Bhatt, R.; Scarino, B. R.; Gopalan, A.

2017-01-01

The Earth Polychromatic Imaging Camera (EPIC) aboard the Deep Space Climate Observatory (DSCOVR) satellite constantly images the sunlit disk of Earth from the Lagrange-1 (L1) point in 10 spectral channels spanning the UV, VIS, and NIR spectrums. Recently, the DSCOVR EPIC team has publicly released version 2 dataset, which has implemented improved navigation, stray-light correction, and flat-fielding of the CCD array. The EPIC 2-year data record must be well-calibrated for consistent cloud, aerosol, trace gas, land use and other retrievals. Because EPIC lacks onboard calibrators, the observations made by EPIC channels must be calibrated vicariously using the coincident measurements from radiometrically stable instruments that have onboard calibration systems. MODIS and VIIRS are best-suited instruments for this task as they contain similar spectral bands that are well-calibrated onboard using solar diffusers and lunar tracking. We have previously calibrated the EPIC version 1 dataset by using EPIC and VIIRS angularly matched radiance pairs over both all-sky ocean and deep convective clouds (DCC). We noted that the EPIC image required navigations adjustments, and that the EPIC stray-light correction provided an offset term closer to zero based on the linear regression of the EPIC and VIIRS ray-matched radiance pairs. We will evaluate the EPIC version 2 navigation and stray-light improvements using the same techniques. In addition, we will monitor the EPIC channel calibration over the two years for any temporal degradation or anomalous behavior. These two calibration methods will be further validated using desert and DCC invariant Earth targets. The radiometric characterization of the selected invariant targets is performed using multiple years of MODIS and VIIRS measurements. Results of these studies will be shown at the conference.

65-nm full-chip implementation using double dipole lithography

NASA Astrophysics Data System (ADS)

Hsu, Stephen D.; Chen, J. Fung; Cororan, Noel; Knose, William T.; Van Den Broeke, Douglas J.; Laidig, Thomas L.; Wampler, Kurt E.; Shi, Xuelong; Hsu, Michael; Eurlings, Mark; Finders, Jo; Chiou, Tsann-Bim; Socha, Robert J.; Conley, Will; Hsieh, Yen W.; Tuan, Steve; Hsieh, Frank

2003-06-01

Double Dipole Lithography (DDL) has been demonstrated to be capable of patterning complex 2D patterns. Due to inherently high aerial imaging contrast, especially for dense features, we have found that it has a very good potential to meet manufacturing requirements for the 65nm node using ArF binary chrome masks. For patterning in the k1<0.35 regime without resorting to hard phase-shift masks (PSMs), DDL is one unique Resolution Enhancement Technique (RET) which can achieve an acceptable process window. To utilize DDL for printing actual IC devices, the original design data must be decomposed into "vertical (V)" and "horizontal (H)" masks for the respective X- and Y-dipole exposures. An improved two-pass, model-based, DDL mask data processing methodology has been established. It is capable of simultaneously converting complex logic and memory mask patterns into DDL compatible mask layout. To maximize the overlapped process window area, we have previously shown that the pattern-shielding algorithm must be intelligently applied together with both Scattering Bars (SBs) and model-based OPC (MOPC). Due to double exposures, stray light must be well-controlled to ensure uniform printing across the entire chip. One solution to minimize stray light is to apply large patches of solid chrome in open areas to reduce the background transmission during exposure. Unfortunately, this is not feasible for a typical clear-field poly gate masks to be patterned by a positive resist process. In this work, we report a production-worthy DDL mask pattern decomposition scheme for full-chip application. A new generation of DDL technology reticle set has been developed to verify the printing performance. Shielding is a critical part of the DDL. An innovative shielding scheme has been developed to protect the critical features and minimize the impact of stray light during double exposure.

Molecular detection of Ehrlichia canis, Hepatozoon canis and Babesia canis vogeli in stray dogs in Mahasarakham province, Thailand.

PubMed

Piratae, Supawadee; Pimpjong, Kiattisak; Vaisusuk, Kotchaphon; Chatan, Wasupon

2015-01-01

Canine tick borne diseases showing distribution worldwide have caused morbidity and mortality in dogs. This study observed the mainly tick borne pathogens described for dogs in Thailand, Ehrlichia canis, Hepatozoon canis and Babesia canis vogeli. From May to July 2014, blood samples were collected from 79 stray dogs from 7 districts of Mahasarakham province to molecular surveyed for 16s rRNA gene of E. canis and 18s rRNA gene of H. canis and B. canis vogeli. Twenty eight (35.44%) of stray dogs showed the infection with tick borne pathogens. The prevalence of E. canis infection was the highest with 21.5% (17/79). DNA of H. canis and B. canis vogeli were detected at the prevalence of 10.1% (8/79) and 6.3% (5/79), respectively. Co-infection between E. canis and B. canis vogeli were identified in 2 (2.5%) dogs. The results indicated that a wide range of tick borne pathogens are circulation in the canine population in Mahasarakham province. This study is the first report on prevalence of E. canis, H. canis and B. canis vogeli in stray dogs in Mahasarakham, a province in northern part of Thailand. This data providing is important to understand the prevalence of E. canis, H. canis and B. canis vogeli infection in stray dogs in this region, which will assist in the management of these blood parasite.

Stray Cats Gastrointestinal Parasites and its Association With Public Health in Ahvaz City, South Western of Iran

PubMed Central

Khademvatan, Shahram; Abdizadeh, Rahman; Rahim, Fakher; Hashemitabar, Mahamoud; Ghasemi, Mohammad; Tavalla, Mahdi

2014-01-01

Background: Cats are the hosts for some zoonotic parasites such as Toxoplasma gondii and Toxocara spp. which are important in medicine and veterinary. Studies on the prevalence of intestinal parasites of cats have received little attention in south west of Iran. Objectives: The current study aimed to investigate the prevalence of parasites in stray cats in Ahvaz. Materials and Methods: Random sampling was carried out from January to May 2012. One hundred and forty fecal samples from stray cats were examined using sucrose flotation method. Results: Gastrointestinal parasites were found in 121 of the 140 (86.4%) examined samples. The parasites detected in stray cats were Toxocara spp. (45%, 63/140), Isospora spp. (21.4%, 30/140), nematode larvae (21.4%, 30/140), Taenia spp. (18.6%, 26/140), Sarcocystis spp. (17.1%, 24/140), Eimeria spp. (15%, 21/140), Blastocystis spp. (14.3%, 20/140), Giardia spp, (10.7%, 15/140), Physaloptera spp. (7.1%, 10/140), and amoeba cyst (5.7%, 8/140) respectively. The prevalence of infection by Joyexiella spp. and hook worms (4.3%, 6/140), for example, Dipylidium caninum (2.9%, 4/140) was similar; and the prevalence of infection by T. gondii and Dicrocoelium dendriticum was similar (1.4%, 2/140). Conclusions: Since the prevalence of zoonotic gastrointestinal parasites such as Toxocara spp. in stray cats is high, there is a need to plan adequate programs to control these zoonotic parasites. PMID:25485047

Microfluidic platform for detection and quantification of magnetic markers

NASA Astrophysics Data System (ADS)

Kokkinis, Georgios; Cardoso, Susana; Giouroudi, Ioanna

2017-05-01

This paper reports on a microfluidic platform with an integrated spin valve giant magneto-resistance (GMR) sensor used for the detection and quantification of single magnetic micromarkers. A microfluidic channel containing the magnetic fluid, microconductors (MCs) for collection of the magnetic markers and a spin valve GMR sensor for detecting the presence of their magnetic stray field were integrated on a single chip. The results show that the sensor is capable of detecting a single magnetic marker with 2.8 μm diameter.

Stray magnetic-field response of linear birefringent optical current sensors

NASA Astrophysics Data System (ADS)

MacDougall, Trevor W.; Hutchinson, Ted F.

1995-07-01

It is well known that the line integral, describing Faraday rotation in an optical medium, reduces to zero at low frequencies for a closed path that does not encircle a current source. If the closed optical path possesses linear birefringence in addition to Faraday rotation, the cumulative effects on the state of polarization result in a response to externally located current-carrying conductors. This effect can induce a measurable error of the order of 0.3% during certain steady-state operating conditions.

Size and spatial distribution of stray dog population in the University of São Paulo campus, Brazil.

PubMed

Dias, Ricardo Augusto; Guilloux, Aline Gil Alves; Borba, Mauro Riegert; Guarnieri, Maria Cristina de Lourdes; Prist, Ricardo; Ferreira, Fernando; Amaku, Marcos; Neto, José Soares Ferreira; Stevenson, Mark

2013-06-01

A longitudinal study was carried out to describe the size and spatial distribution of the stray dog population in the University of São Paulo campus, Brazil from November 2010 to November 2011. The campus is located within the urban area of São Paulo, the largest city of Brazil, with a population over 11 million. The 4.2 km(2) that comprise the university grounds are walled, with 10 access gates, allowing stray dogs to move in and out freely. Over 100,000 people and 50,000 vehicles circulate in the campus daily. Five observations were made during the study period, using a mark-resight method. The same route was performed in all observations, being traveled twice on each observation day. Observed animals were photographed and the sight coordinates were obtained using a GPS device. The estimated size of the stray dog population varied from 32 (CI 95% 23-56) to 56 (CI 95% 45-77) individuals. Differences between in- and outward dog movements influenced dog population estimates. Overlapping home ranges of docile dogs were observed in areas where most people circulate. An elusive group was observed close to a protected rain forest area and the estimated home range for this group did not overlap with the home ranges for other dogs within the campus. A kernel density map showed that higher densities of stray dog sighting is associated with large organic matter generators, such as university restaurants. We conclude that the preferred source of food of the stray dogs on the University of São Paulo campus was leftover food deliberately offered by restaurant users. The population was stable during the study period and the constant source of food was the main reason to retain this population within the campus. Copyright © 2012 Elsevier B.V. All rights reserved.

Genetic characterization of Toxoplasma gondii isolates and toxoplasmosis seroprevalence in stray cats of İzmir, Turkey.

PubMed

Can, Hüseyin; Döşkaya, Mert; Ajzenberg, Daniel; Özdemir, H Gökhan; Caner, Ayşe; İz, Sultan Gülce; Döşkaya, Aysu Değirmenci; Atalay, Esra; Çetinkaya, Çağdaş; Ürgen, Saygun; Karaçalı, Sabire; Ün, Cemal; Dardé, Marie-Laure; Gürüz, Yüksel

2014-01-01

Currently, some Toxoplasma gondii genotypes are being associated with serious clinical presentations. A recent report showing the Africa 1 genotype in two local congenital toxoplasmosis cases acquired in Turkey formed the basis of this study because atypical Africa 1 genotype is most frequently detected in animals and patients from sub-Saharan Africa. Since stray cats are considered as the linkage between wild life and urban life in T. gondii transmission, the present study aimed to isolate and characterize T. gondii strains circulating in stray cats of İzmir (Western Turkey). A secondary objective was to determine toxoplasmosis seroprevalence in this cat population. Tissues obtained from 100 deceased stray cats were bioassayed and isolated strains were genotyped using 15 microsatellite markers. In addition, toxoplasmosis seroprevalence was analyzed in 1121 cat sera collected from several large veterinary clinics in İzmir. Among the 22 isolates, 19 were Type II (86.3%), two were Type III (9%) and one was Africa 1 genotype (4.5%). The overall seropositivity rates in cats were 42-48% and 33.4-34.4% according to IFA and ELISA, respectively. Seroprevalence in deceased cats was significantly higher than in healthy cats (P = 0.0033). Finding both the major clonal Type II lineage together with the Type III lineage also found in Middle East, and an atypical genotype, Africa 1 appears consistent with the specific geographic location of Turkey between three continents and raises the possibility of transportation of these strains between continents through trade routes or long distance migratory birds. In addition, the first large study of toxoplasma seroprevalence in a stray cat population was also reported. The relatively high seropositivity rates and the variety of T. gondii genotypes confirm the local stray cat population as a risk factor for human toxoplasmosis in İzmir.

Genetic Characterization of Toxoplasma gondii Isolates and Toxoplasmosis Seroprevalence in Stray Cats of İzmir, Turkey

PubMed Central

Can, Hüseyin; Döşkaya, Mert; Ajzenberg, Daniel; Özdemir, H. Gökhan; Caner, Ayşe; İz, Sultan Gülce; Döşkaya, Aysu Değirmenci; Atalay, Esra; Çetinkaya, Çağdaş; Ürgen, Saygun; Karaçalı, Sabire; Ün, Cemal; Dardé, Marie-Laure; Gürüz, Yüksel

2014-01-01

Currently, some Toxoplasma gondii genotypes are being associated with serious clinical presentations. A recent report showing the Africa 1 genotype in two local congenital toxoplasmosis cases acquired in Turkey formed the basis of this study because atypical Africa 1 genotype is most frequently detected in animals and patients from sub-Saharan Africa. Since stray cats are considered as the linkage between wild life and urban life in T. gondii transmission, the present study aimed to isolate and characterize T. gondii strains circulating in stray cats of İzmir (Western Turkey). A secondary objective was to determine toxoplasmosis seroprevalence in this cat population. Tissues obtained from 100 deceased stray cats were bioassayed and isolated strains were genotyped using 15 microsatellite markers. In addition, toxoplasmosis seroprevalence was analyzed in 1121 cat sera collected from several large veterinary clinics in İzmir. Among the 22 isolates, 19 were Type II (86.3%), two were Type III (9%) and one was Africa 1 genotype (4.5%). The overall seropositivity rates in cats were 42–48% and 33.4–34.4% according to IFA and ELISA, respectively. Seroprevalence in deceased cats was significantly higher than in healthy cats (P = 0.0033). Finding both the major clonal Type II lineage together with the Type III lineage also found in Middle East, and an atypical genotype, Africa 1 appears consistent with the specific geographic location of Turkey between three continents and raises the possibility of transportation of these strains between continents through trade routes or long distance migratory birds. In addition, the first large study of toxoplasma seroprevalence in a stray cat population was also reported. The relatively high seropositivity rates and the variety of T. gondii genotypes confirm the local stray cat population as a risk factor for human toxoplasmosis in İzmir. PMID:25127360

Feline immunodeficiency virus testing in stray, feral, and client-owned cats of Ottawa

PubMed Central

2005-01-01

Abstract Feline immunodeficiency virus (FIV) seroprevalence is evaluated in 3 groups of cats. Seventy-four unowned urban strays were tested, as well as 20 cats from a small feral cat colony, and 152 client-owned cats. Of the 246 cats tested, 161 (65%) were male and 85 (35%) were female. Seroprevalence for FIV was 23% in the urban strays, 5% in the feral cat colony, and 5.9% in the client-owned cats. Ten cats (4%) were also positive for Feline leukemia virus (FeLV) antigen, including 2 cats coinfected with FeLV and FIV. Seroprevalence for FIV in cats from Ottawa is similar to that found in other nonrandom studies of cats in North America. PMID:16454381

Feline immunodeficiency virus testing in stray, feral, and client-owned cats of Ottawa.

PubMed

Little, Susan E

2005-10-01

Feline immunodeficiency virus (FIV) seroprevalence is evaluated in 3 groups of cats. Seventy-four unowned urban strays were tested, as well as 20 cats from a small feral cat colony, and 152 client-owned cats. Of the 246 cats tested, 161 (65%) were male and 85 (35%) were female. Seroprevalence for FIV was 23% in the urban strays, 5% in the feral cat colony, and 5.9% in the client-owned cats. Ten cats (4%) were also positive for Feline leukemia virus (FeLV) antigen, including 2 cats coinfected with FeLV and FIV. Seroprevalence for FIV in cats from Ottawa is similar to that found in other nonrandom studies of cats in North America.

Contamination control program for the Cosmic Background Explorer

NASA Technical Reports Server (NTRS)

Barney, Richard D.

1991-01-01

Each of the three state of the art instruments flown aboard NASA's Cosmic Background Explorer (COBE) were designed, fabricated, and integrated using unique contamination control procedures to ensure accurate characterization of the diffuse radiation in the universe. The most stringent surface level cleanliness specifications ever attempted by NASA were required by the Diffuse Infrared Background Experiment (DRIBE) which is located inside a liquid helium cooled dewar along with the Far Infrared Absolute Spectrophotometer (FIRAS). The DRIBE instrument required complex stray radiation suppression that defined a cold primary optical baffle system surface cleanliness level of 100A. The cleanliness levels of the cryogenic FIRAS instrument and the Differential Microwave Radiometer (DMR) which were positioned symmetrically around the dewar were less stringent ranging from 300 to 500A. To achieve these instrument cleanliness levels, the entire flight spacecraft was maintained at level 500A throughout each phase of development. The COBE contamination control program is described along with the difficulties experienced in maintaining the cleanliness quality of personnel and flight hardware throughout instrument assembly.

Induced Radioactivity in Lead Shielding at the National Synchrotron Light Source

DOE PAGES

Ghosh, Vinita J.; Schaefer, Charles; Kahnhauser, Henry

2017-06-30

The National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory was shut down in September 2014. Lead bricks used as radiological shadow shielding within the accelerator were exposed to stray radiation fields during normal operations. The FLUKA code, a fully integrated Monte Carlo simulation package for the interaction and transport of particles and nuclei in matter, was used to estimate induced radioactivity in this shielding and stainless steel beam pipe from known beam losses. The FLUKA output was processed using MICROSHIELD® to estimate on-contact exposure rates with individually exposed bricks to help design and optimize the radiological survey process. Thismore » entire process can be modeled using FLUKA, but use of MICROSHIELD® as a secondary method was chosen because of the project’s resource constraints. Due to the compressed schedule and lack of shielding configuration data, simple FLUKA models were developed in this paper. FLUKA activity estimates for stainless steel were compared with sampling data to validate results, which show that simple FLUKA models and irradiation geometries can be used to predict radioactivity inventories accurately in exposed materials. During decommissioning 0.1% of the lead bricks were found to have measurable levels of induced radioactivity. Finally, post-processing with MICROSHIELD® provides an acceptable secondary method of estimating residual exposure rates.« less

Induced Radioactivity in Lead Shielding at the National Synchrotron Light Source.

PubMed

Ghosh, Vinita J; Schaefer, Charles; Kahnhauser, Henry

2017-06-01

The National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory was shut down in September 2014. Lead bricks used as radiological shadow shielding within the accelerator were exposed to stray radiation fields during normal operations. The FLUKA code, a fully integrated Monte Carlo simulation package for the interaction and transport of particles and nuclei in matter, was used to estimate induced radioactivity in this shielding and stainless steel beam pipe from known beam losses. The FLUKA output was processed using MICROSHIELD® to estimate on-contact exposure rates with individually exposed bricks to help design and optimize the radiological survey process. This entire process can be modeled using FLUKA, but use of MICROSHIELD® as a secondary method was chosen because of the project's resource constraints. Due to the compressed schedule and lack of shielding configuration data, simple FLUKA models were developed. FLUKA activity estimates for stainless steel were compared with sampling data to validate results, which show that simple FLUKA models and irradiation geometries can be used to predict radioactivity inventories accurately in exposed materials. During decommissioning 0.1% of the lead bricks were found to have measurable levels of induced radioactivity. Post-processing with MICROSHIELD® provides an acceptable secondary method of estimating residual exposure rates.

Detection of Hepatozoon canis in stray dogs and cats in Bangkok, Thailand.

PubMed

Jittapalapong, Sathaporn; Rungphisutthipongse, Opart; Maruyama, Soichi; Schaefer, John J; Stich, Roger W

2006-10-01

A rapidly increasing stray animal population in Bangkok has caused concern regarding transmission of vector-borne and zoonotic diseases. The purpose of this study was to determine if stray animals in Bangkok are a potential reservoir of Hepatozoon, a genus of tick-borne parasites that has received little attention in Thailand. Blood samples were collected from stray companion animals near monasteries in 42 Bangkok metropolitan districts. Both dogs and cats were sampled from 26 districts, dogs alone from 4 districts and cats alone from 12 districts. Samples were collected from a total of 308 dogs and 300 cats. Light microscopy and an 18 S rRNA gene-based PCR assay were used to test these samples for evidence of Hepatozoon infection. Gamonts were observed in blood smears for 2.6% of dogs and 0.7% of cats by microscopy. The PCR assay detected Hepatozoon in buffy coats from 11.4% of dogs and 32.3% of cats tested. The prevalence of infection was the same between male and female dogs or cats, and PCR-positive dogs and cats were found in 36.6% and 36.8% of the districts surveyed, respectively. There was an association between the percentages of PCR-positive dogs and cats in districts where both host species were sampled. Sequences of representative amplicons were closest to those reported for H. canis. These results represent the first molecular confirmation that H. canis is indigenous to Thailand. The unexpectedly high prevalence of Hepatozoon among stray cats indicates that their role in the epizootiology of hepatozoonosis should be investigated.

Identification of pixels with stray light and cloud shadow contaminations in the satellite ocean color data processing.

PubMed

Jiang, Lide; Wang, Menghua

2013-09-20

A new flag/masking scheme has been developed for identifying stray light and cloud shadow pixels that significantly impact the quality of satellite-derived ocean color products. Various case studies have been carried out to evaluate the performance of the new cloud contamination flag/masking scheme on ocean color products derived from the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP). These include direct visual assessments, detailed quantitative case studies, objective statistic analyses, and global image examinations and comparisons. The National Oceanic and Atmospheric Administration (NOAA) Multisensor Level-1 to Level-2 (NOAA-MSL12) ocean color data processing system has been used in the study. The new stray light and cloud shadow identification method has been shown to outperform the current stray light flag in both valid data coverage and data quality of satellite-derived ocean color products. In addition, some cloud-related flags from the official VIIRS-SNPP data processing software, i.e., the Interface Data Processing System (IDPS), have been assessed. Although the data quality with the IDPS flags is comparable to that of the new flag implemented in the NOAA-MSL12 ocean color data processing system, the valid data coverage from the IDPS is significantly less than that from the NOAA-MSL12 using the new stray light and cloud shadow flag method. Thus, the IDPS flag/masking algorithms need to be refined and modified to reduce the pixel loss, e.g., the proposed new cloud contamination flag/masking can be implemented in IDPS VIIRS ocean color data processing.

The LSST Dome final design

NASA Astrophysics Data System (ADS)

DeVries, J.; Neill, D. R.; Barr, J.; De Lorenzi, Simone; Marchiori, Gianpietro

2016-07-01

The Large Synoptic Survey Telescope (LSST) is a large (8.4 meter) wide-field (3.5 degree) survey telescope, which will be located on the Cerro Pachón summit in Chile 1. As a result of the Telescope wide field of view, the optical system is unusually susceptible to stray light 2. In addition, balancing the effect of wind induced telescope vibrations with Dome seeing is crucial. The rotating enclosure system (Dome) includes a moving wind screen and light baffle system. All of the Dome vents include hinged light baffles, which provide exceptional Dome flushing, stray light attenuation, and allows for vent maintenance access from inside the Dome. The wind screen also functions as a light screen, and helps define a clear optical aperture for the Telescope. The Dome must operate continuously without rotational travel limits to accommodate the Telescope cadence and travel. Consequently, the Azimuth drives are located on the fixed lower enclosure to accommodate glycol water cooling without the need for a utility cable wrap. An air duct system aligns when the Dome is in its parked position, and this provides air cooling for temperature conditioning of the Dome during the daytime. A bridge crane and a series of ladders, stairs and platforms provide for the inspection, maintenance and repair of all of the Dome mechanical systems. The contract to build the Dome was awarded to European Industrial Engineering in Mestre, Italy in May 2015. In this paper, we present the final design of this telescope and site sub-system.

Optical design of the STAR-X telescope

NASA Astrophysics Data System (ADS)

Saha, Timo T.; Zhang, William W.; McClelland, Ryan S.

2017-08-01

Top-level science objectives of the Survey and Time-domain Astrophysical Research eXplorer (STAR-X) include: investigations of most violent explosions in the universe, study of growth of black holes across cosmic time and mass scale, and measure how structure formation heats majority of baryons in the universe. To meet these objectives, the STAR-X telescope requires a field of view of about 1 square-degree, an angular resolution of 5 arc-seconds or better across large part of the field of view. The on-axis effective area at 1 keV should be about 2,000 cm2 . Payload cost and launch considerations limit the outer diameter, focal length, and mass to 1.3 meters, 5 meters, and 250 kilograms, respectively. Telescope design is based on a segmented meta-shell approach we have developed at Goddard Space Flight Center. The telescope mirror shells are divided into segments. Individual shells are nested inside each other to meet the effective area requirements in 0.5 - 6.0 keV range. We consider Wolter-Schwarzschild, and Modified-WolterSchwarzschild telescopes. These designs offer an excellent PSF over a large field of view. Nested shells are vulnerable to stray light problems. We have designed a multi-component baffle system to eliminate direct and single-reflection light paths inside the mirror assembly. Large numbers of internal and external baffles are required to prevent stray rays from reaching the focal plane. We have developed a simple ray-trace tool to determine the dimensions and locations of the baffles. In this paper, we present the results of our trade studies, baffle design studies, and optical performance analyses of the STAR-X telescope.

Design of the STAR-X Telescope

NASA Technical Reports Server (NTRS)

Saha, Timo T.; Zhang, William W.; McClelland, Ryan S.

2017-01-01

Top-level science goals of the Survey and Time-domain Astrophysical Research eXplorer (STAR-X) include: investigations of most violent explosions in the universe, study of growth of black holes across cosmic time and mass scale, and measure how structure formation heats majority of baryons in the universe. To meet these goals, the field-of-view of the telescope should be about 1 square-degree, the angular resolution should be 5 arc-seconds or below across large part of the field-of-view. The on-axis effective area at 1 KeV should be about 2,000 sq cm. Payload cost and launch considerations limit the outer diameter, focal length, and mass to 1.3 meters, 5 meters, and 250 kilograms, respectively. Telescope design is based on a segmented meta-shell approach we have developed at Goddard Space Flight Center for the STAR-X telescope. The telescope shells are divided into 30-degree segments. Individual telescopes and meta-shells are nested inside each other to meet the effective area requirements in 0.5 - 6.0 KeV range. We consider Wolter-Schwarzschild, and Modified-Wolter-Schwarzschild telescope designs as basic building blocks of the nested STAR-X telescope. These designs offer an excellent resolution over a large field of views. Nested telescopes are vulnerable to stray light problems. We have designed a multi-component baffle system to eliminate direct and single-reflection light paths inside the telescopes. Large number of internal and external baffle vane structures are required to prevent stray rays from reaching the focal plane. We have developed a simple ray-trace based tool to determine the dimensions and locations of the baffles. In this paper, we present the results of our trade studies, baffle design studies, and optical performance analyses of the STAR-X telescope.

Optical Design of the STAR-X Telescope

NASA Technical Reports Server (NTRS)

Saha, Timo T.; Zhang, William W.; McClelland, Ryan S.

2017-01-01

Top-level science goals of the Survey and Time-domain Astrophysical Research eXplorer (STAR-X) include: investigations of most violent explosions in the universe, study of growth of black holes across cosmic time and mass scale, and measure how structure formation heats majority of baryons in the universe. To meet these goals, the field-of-view of the telescope should be about 1 square-degree, the angular resolution should be 5 arc-seconds or below across large part of the field-of-view. The on-axis effective area at 1 KeV should be about 2,000 sq cm. Payload cost and launch considerations limit the outer diameter, focal length, and mass to 1.3 meters, 5 meters, and 250 kilograms, respectively. Telescope design is based on a segmented meta-shell approach we have developed at Goddard Space Flight Center for the STAR-X telescope. The telescope shells are divided into 30-degree segments. Individual telescopes and meta-shells are nested inside each other to meet the effective area requirements in 0.5 - 6.0 KeV range. We consider Wolter-Schwarzschild, and Modified-Wolter-Schwarzschild telescope designs as basic building blocks of the nested STAR-X telescope. These designs offer an excellent resolution over a large field of views. Nested telescopes are vulnerable to stray light problems. We have designed a multi-component baffle system to eliminate direct and single-reflection light paths inside the telescopes. Large number of internal and external baffle vane structures are required to prevent stray rays from reaching the focal plane. We have developed a simple ray-trace based tool to determine the dimensions and locations of the baffles. In this paper, we present the results of our trade studies, baffle design studies, and optical performance analyses of the STAR-X telescope.

Development of a neutron spectrometer using multi-wire spark chambers for the measurement of the spectra of stray neutrons in the vicinity of high energy accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Chun Bin

A method of neutron spectrometry which measures the energy spectra of the stray neutrons around the high energy accelerators, roughly between 50 MeV and 300 MeV has been developed using a series of multi-wire spark chambers and polyethylene n-p converters.

Image and Processing Models for Satellite Detection in Images Acquired by Space-based Surveillance-of-Space Sensors

DTIC Science & Technology

2010-09-01

external sources ‘L1’ like zodiacal light (or diffuse nebula ) or stray light ‘L2’ and these components change with the telescope pointing. Bk (T,t...Astronomical scene background (zodiacal light, diffuse nebulae , etc.). L2(P A(tk), t): Image background component caused by stray light. MS

Configuration and validation of an analytical model predicting secondary neutron radiation in proton therapy using Monte Carlo simulations and experimental measurements.

PubMed

Farah, J; Bonfrate, A; De Marzi, L; De Oliveira, A; Delacroix, S; Martinetti, F; Trompier, F; Clairand, I

2015-05-01

This study focuses on the configuration and validation of an analytical model predicting leakage neutron doses in proton therapy. Using Monte Carlo (MC) calculations, a facility-specific analytical model was built to reproduce out-of-field neutron doses while separately accounting for the contribution of intra-nuclear cascade, evaporation, epithermal and thermal neutrons. This model was first trained to reproduce in-water neutron absorbed doses and in-air neutron ambient dose equivalents, H*(10), calculated using MCNPX. Its capacity in predicting out-of-field doses at any position not involved in the training phase was also checked. The model was next expanded to enable a full 3D mapping of H*(10) inside the treatment room, tested in a clinically relevant configuration and finally consolidated with experimental measurements. Following the literature approach, the work first proved that it is possible to build a facility-specific analytical model that efficiently reproduces in-water neutron doses and in-air H*(10) values with a maximum difference less than 25%. In addition, the analytical model succeeded in predicting out-of-field neutron doses in the lateral and vertical direction. Testing the analytical model in clinical configurations proved the need to separate the contribution of internal and external neutrons. The impact of modulation width on stray neutrons was found to be easily adjustable while beam collimation remains a challenging issue. Finally, the model performance agreed with experimental measurements with satisfactory results considering measurement and simulation uncertainties. Analytical models represent a promising solution that substitutes for time-consuming MC calculations when assessing doses to healthy organs. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Horse impoundments under Control of Horses legislation in the Munster region of Ireland: factors affecting euthanasia.

PubMed

Cullinane, M; O'Sullivan, E; Collins, D M; Byrne, A W; More, S J

2015-01-24

Recently, considerable international attention has been paid to the problem of unwanted horses. In Ireland, stray horses, particularly in urban areas, are a further problem. The Control of Horses Act 1996 was enacted in response to an ongoing problem of uncontrolled horses in public places. As yet, no research work has been conducted focusing on stray horses in Ireland. This paper describes horses impounded under the Act in the Munster region of Ireland during 2005-2012 and the factors influencing decisions regarding their disposal. A logistic regression model was developed to investigate factors influencing the probability that a horse was euthanised during impoundment. In total, 3625 seizure events were recorded, most towards the end of the study period. Predictors for euthanasia during 2010-2012 included seizure location, sex, age, colour, body condition score and year. This study highlights the problem of stray horses in Ireland, particularly in urban areas. There is a need for rigorous enforcement of newly enacted horse identification legislation, allowing a fully integrated traceability system. More is required to manage the long-established societal problems of stray horses in urban settings, with a uniform approach by all Local Authorities being long overdue. British Veterinary Association.

[Scattered light and glare sensitivity after wavefront-guided photorefractive keratectomy (WFG-PRK) and laser in situ keratomileusis (WFG-LASIK)].

PubMed

Vignal, R; Tanzer, D; Brunstetter, T; Schallhorn, S

2008-05-01

To compare glare sensitivity measured by the intraocular scattered light between WFG-PRK and WFG-LASIK at 12 months follow-up and to assess its correlation to patients' complaints. Prospective and randomized study on 13 patients treated with WFG-LASIK, 13 patients with WFG-PRK and a control group of 35 patients. The intraocular stray light was measured by the Oculus C-Quant 12 months after surgery and before surgery for the control group. Photopic and mesopic contrast acuity and glare symptoms were reported pre- and postoperatively. Stray light values were normal in 79% of patients after WFG-LASIK and PRK and 86% in the control group, with mean values of 1.05 log, 1.03 log, and 0.99 log, respectively (p>0.05). All the patients with significant glare complaints had impaired stray light values versus 31.5% in the no-complaint group. Photopic and mesopic contrast acuity and glare symptoms were improved 1 year after surgery compared to preoperatively (no significant difference between groups). WFG-LASIK and PRK are safe and equivalent procedures regarding quality of vision. The measurement of stray light can be a discriminative test to assessing patients' glare complaints.

Toxoplasmosis, leptospirosis and brucellosis in stray dogs housed at the shelter in Umuarama municipality, Paraná, Brazil

PubMed Central

2013-01-01

Background Leptospirosis, toxoplasmosis and brucellosis are diseases with worldwide distribution. Among stray dogs, these zoonoses are facilitated by direct contact with other animal species, by the habit of scavenging garbage and hunting in search of food, drinking standing water, smelling other animals’ urine, licking female genitalia and the sexual act itself. The objective of this study was to detect antibodies anti-Toxoplasma gondii, anti-Leptospira spp., anti-Brucella canis and anti-Brucella abortus in stray dogs housed in shelters at Umuarama city, Paraná, Brazil. In order to detect toxoplasmosis, indirect immunofluorescence assay (IFA) was performed, agglutination microscopic (MAT) test for leptospirosis and agar gel immunodiffusion (AGID) and buffered acidified antigen (BAA) tests for brucellosis. Results Of the 175 serum samples analyzed, 70.85% were considered positive for toxoplasmosis by IFA, 20% by MAT for leptospirosis and 2.85% by AGID for Brucella canis. Conclusions The serological results of this study showed that stray dogs housed at the private shelter are potential carriers of these three different zoonoses and contribute to the spread and maintenance of these etiologic agents in the urban area of Umuarama (PR), Brazil. PMID:24066949

Rapid optimization method of the strong stray light elimination for extremely weak light signal detection.

PubMed

Wang, Geng; Xing, Fei; Wei, Minsong; You, Zheng

2017-10-16

The strong stray light has huge interference on the detection of weak and small optical signals, and is difficult to suppress. In this paper, a miniaturized baffle with angled vanes was proposed and a rapid optimization model of strong light elimination was built, which has better suppression of the stray lights than the conventional vanes and can optimize the positions of the vanes efficiently and accurately. Furthermore, the light energy distribution model was built based on the light projection at a specific angle, and the light propagation models of the vanes and sidewalls were built based on the Lambert scattering, both of which act as the bias of a calculation method of stray light. Moreover, the Monte-Carlo method was employed to realize the Point Source Transmittance (PST) simulation, and the simulation result indicated that it was consistent with the calculation result based on our models, and the PST could be improved by 2-3 times at the small incident angles for the baffle designed by the new method. Meanwhile, the simulation result was verified by laboratory tests, and the new model with derived analytical expressions which can reduce the simulation time significantly.

Spin Vector Distribution in the Koronis Family for a Sample Complete to IAU H=10.88

NASA Astrophysics Data System (ADS)

Slivan, Stephen M.; Hosek, Matt; Sokol, Alyssa; Maynard, Sarah; Payne, Anna; Radford, Arden; Springmann, Alessondra; Mailhot, Emily; Midkiff, Alan; Russell, April; Stephens, Robert D.

2016-10-01

Because they share the same formation age, asteroid family members have experienced similar evolution for similar lengths of time, offering valuable information to help understand spin evolution processes. Clustered distributions of spin vectors determined from observations of ten of the largest Koronis family members (Slivan 2002) revealed evidence of spin modification by YORP thermal radiation torques (Vokrouhlický et al. 2003). The currently known spin vector sample in the Koronis family (Slivan et al., 2003; Slivan et al., 2009, Hanuš et al., 2011; Hanuš et al., 2013; Durech et al., 2016) clearly shows the two spin groupings observed among the large members: (1) the larger group with low-obliquity retrograde spin and periods between about 3 h and 30 h, and (2) a smaller group with prograde spin obliquity near 45° and periods near 8 h, characteristic of trapping in the s6 spin-orbit resonance (Vokrouhlický et al. 2003). There's also one "stray" longer-period prograde object with smaller obliquity, perhaps trapped in some other resonance.A limitation of the existing spin vector sample, which (using IAU H as a proxy for size) includes 16 of the brightest 27 members of the family, is that selection biases render it complete only to the brightest 12 members. Slivan et al. (2008) began a lightcurve observing program to increase the sample of Koronis family spin vectors down to about 20 km diameter.We report pole solutions that were determined for fourteen survey objects using lightcurves recorded from 2005-2016, which complete the Koronis spin vector sample to the brightest 22 members, now including 24 of the brightest 27 members. The larger sample adds several objects to the existing group of low-obliquity retrograde rotators, increasing the period range upward to almost 60 h, and also identifies two companions for the stray longer-period prograde spin object, strengthening the case for the presence of a second cluster of objects trapped in a spin-orbit resonance. The more complete distribution also reveals two new "strays" of its own - one lone fast prograde rotator, and one spin vector of atypical high obliquity, close to the ecliptic plane.

Tunable interactions between paramagnetic colloidal particles driven in a modulated ratchet potential.

PubMed

Straube, Arthur V; Tierno, Pietro

2014-06-14

We study experimentally and theoretically the interactions between paramagnetic particles dispersed in water and driven above the surface of a stripe patterned magnetic garnet film. An external rotating magnetic field modulates the stray field of the garnet film and generates a translating potential landscape which induces directed particle motion. By varying the ellipticity of the rotating field, we tune the inter-particle interactions from net repulsive to net attractive. For attractive interactions, we show that pairs of particles can approach each other and form stable doublets which afterwards travel along the modulated landscape at a constant mean speed. We measure the strength of the attractive force between the moving particles and propose an analytically tractable model that explains the observations and is in quantitative agreement with experiment.

Irreversible magnetization switching at the onset of superconductivity in a superconductor ferromagnet hybrid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curran, P. J.; Bending, S. J.; Kim, J.

2015-12-28

We demonstrate that the magnetic state of a superconducting spin valve, that is normally controlled with an external magnetic field, can also be manipulated by varying the temperature which increases the functionality and flexibility of such structures as switching elements. In this case, switching is driven by changes in the magnetostatic energy due to spontaneous Meissner screening currents forming in the superconductor below the critical temperature. Our scanning Hall probe measurements also reveal vortex-mediated pinning of the ferromagnetic domain structure due to the pinning of quantized stray fields in the adjacent superconductor. The ability to use temperature as well asmore » magnetic field to control the local magnetisation structure raises the prospect of potential applications in magnetic memory devices.« less

Spectrometry and filtering with high rejection of stray light

DOEpatents

Ferrell, Thomas L.; Thundat, Thomas G.

2004-12-14

A microoptoelectromechanical integrated spectrometer with a photonic element assembly having metal foil removably disposed on a first transparent substrate surface, the substrate having no foil on any other surface. A means is provided for directing source photons that are reflected from or transmitted through a sample, over a range of angles of incidence, into the transparent substrate and onto the metal foil such that source photons are incident at the Brewsters angle. A means is also provided for detecting an induced exponential field in the metal foil. A means is also provided for relating the induced exponential field to a known exponential field for the sample and determining the identity of the sample. The spectrometer performs ultraviolet-to-visible-to-infrared spectroscopy using photon tunneling and surface plasmon excitation.

A Bonner Sphere Spectrometer for pulsed fields

PubMed Central

Aza, E.; Dinar, N.; Manessi, G. P.; Silari, M.

2016-01-01

The use of conventional Bonner Sphere Spectrometers (BSS) in pulsed neutron fields (PNF) is limited by the fact that proportional counters, usually employed as the thermal neutron detectors, suffer from dead time losses and show severe underestimation of the neutron interaction rate, which leads to strong distortion of the calculated spectrum. In order to avoid these limitations, an innovative BSS, called BSS-LUPIN, has been developed for measuring in PNF. This paper describes the physical characteristics of the device and its working principle, together with the results of Monte Carlo simulations of its response matrix. The BSS-LUPIN has been tested in the stray neutron field at the CERN Proton Synchrotron, by comparing the spectra obtained with the new device, the conventional CERN BSS and via Monte Carlo simulations. PMID:25948828

Circular-polarization-sensitive metamaterial based on triple-quantum-dot molecules.

PubMed

Kotetes, Panagiotis; Jin, Pei-Qing; Marthaler, Michael; Schön, Gerd

2014-12-05

We propose a new type of chiral metamaterial based on an ensemble of artificial molecules formed by three identical quantum dots in a triangular arrangement. A static magnetic field oriented perpendicular to the plane breaks mirror symmetry, rendering the molecules sensitive to the circular polarization of light. By varying the orientation and magnitude of the magnetic field one can control the polarization and frequency of the emission spectrum. We identify a threshold frequency Ω, above which we find strong birefringence. In addition, Kerr rotation and circular-polarized lasing action can be implemented. We investigate the single-molecule lasing properties for different energy-level arrangements and demonstrate the possibility of circular-polarization conversion. Finally, we analyze the effect of weak stray electric fields or deviations from the equilateral triangular geometry.

Design and performance of the collective Thomson scattering receiver at ASDEX Upgrade.

PubMed

Furtula, V; Salewski, M; Leipold, F; Michelsen, P K; Korsholm, S B; Meo, F; Moseev, D; Nielsen, S K; Stejner, M; Johansen, T

2012-01-01

Here we present the design of the fast-ion collective Thomson scattering receiver for millimeter wave radiation installed at ASDEX Upgrade, a tokamak for fusion plasma experiments. The receiver can detect spectral power densities of a few eV against the electron cyclotron emission background on the order of 100 eV under presence of gyrotron stray radiation that is several orders of magnitude stronger than the signal to be detected. The receiver down converts the frequencies of scattered radiation (100-110 GHz) to intermediate frequencies (IF) (4.5-14.5 GHz) by heterodyning. The IF signal is divided into 50 IF channels tightly spaced in frequency space. The channels are terminated by square-law detector diodes that convert the signal power into DC voltages. We present measurements of the transmission characteristics and performance of the main receiver components operating at mm-wave frequencies (notch, bandpass, and lowpass filters, a voltage-controlled variable attenuator, and an isolator), the down-converter unit, and the IF components (amplifiers, bandpass filters, and detector diodes). Furthermore, we determine the performance of the receiver as a unit through spectral response measurements and find reasonable agreement with the expectation based on the individual component measurements.

Stray light modeling of the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM)

NASA Astrophysics Data System (ADS)

Rohrbach, Scott O.; Irvin, Ryan G.; Seals, Lenward T.; Skelton, Dennis L.

2016-09-01

This paper describes an integrated stray light model of each Science Instrument (SI) in the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) and the Optical Telescope Element Simulator (OSIM), the light source used to characterize the performance of ISIM in cryogenic-vacuum tests at the Goddard Space Flight Center (GSFC). We present three cases where this stray light model was integral to solving questions that arose during the testing campaign - 1) ghosting and coherent diffraction from hardware surfaces in the Near Infrared Imager and Slitless Spectrograph (NIRISS) GR700XD grism mode, 2) ghost spots in the Near Infrared Camera (NIRCam) GRISM modes, and 3) scattering from knife edges of the NIRCam focal plane array masks.

Integrated focal plane arrays for millimeter-wave astronomy

NASA Astrophysics Data System (ADS)

Bock, James J.; Goldin, Alexey; Hunt, Cynthia; Lange, Andrew E.; Leduc, Henry G.; Day, Peter K.; Vayonakis, Anastasios; Zmuidzinas, Jonas

2002-02-01

We are developing focal plane arrays of bolometric detectors for sub-millimeter and millimeter-wave astrophysics. We propose a flexible array architecture using arrays of slot antennae coupled via low-loss superconducting Nb transmission line to microstrip filters and antenna-coupled bolometers. By combining imaging and filtering functions with transmission line, we are able to realize unique structures such as a multi-band polarimeter and a planar, dispersive spectrometer. Micro-strip bolometers have significantly smaller active volume than standard detectors with extended absorbers, and can realize higher sensitivity and speed of response. The integrated array has natural immunity to stray radiation or spectral leaks, and minimizes the suspended mass operating at 0.1-0.3 K. We also discuss future space-borne spectroscopy and polarimetry applications. .

Coronagraphic and low-emissivity astronomical reflector (CLEAR): heat trap design

NASA Astrophysics Data System (ADS)

Siegmund, Walter A.

1998-08-01

The heat trap in a coronagraphic telescope is located at its prime focus and blocks the transmission of radiation from unwanted portions of the solar disk to subsequent optics in the telescope. This reduces light scattered and heat absorbed by these optics. For observations of the corona, the solar disk is completely blocked, whereas for observations of the disk, typically 90% or more of the disk is blocked. The proposed heat trap design is constructed largely of fused silica plates, partially coated with platinum, and cooled with air. It is robust and handles high irradiance, i.e., almost f megawatt/m(superscript 2) at f/3.75, without degrading the image quality of the telescope or contributing significant stray light to the focal surface.

ASPIICS/PROBA-3 formation flying solar coronagraph: Stray light analysis and optimization of the occulter

NASA Astrophysics Data System (ADS)

Landini, F.; Mazzoli, A.; Venet, M.; Vivès, S.; Romoli, M.; Lamy, P.; Massone, G.

2017-11-01

The "Association de Satellites Pour l'Imagerie et l'Interferometrie de la Couronne Solaire", ASPIICS, selected by ESA for the PROBA-3 mission, heralds the next generation of coronagraph for solar research, exploiting formation flying to gain access to the inner corona under eclipse-like conditions for long periods of time. A detailed description of the ASPIICS instrument and of its scientific objectives can be found in [1]. ASPIICS is distributed on the two PROBA 3 spacecrafts (S/C) separated by 150 m. The coronagraph optical assembly is hosted by the "coronagraph S/C" protected from direct solar disk light by the occulting disk on the "occulter S/C". The most critical issue in the design of a solar coronagraph is the reduction of the stray light due to the diffraction and scattering of the solar disk light by the occulter, the aperture and the optics. In the present article, we deal with two of these issues: - The analysis of the stray light inside the telescope. - The optimization of the external occulter edge, in order to eliminate the Poisson spot behind the occulter and to lower the stray light level going through the entrance pupil of the telescope. This work was performed in the framework of the ESA STARTIGER program which took place at the Laboratoire d'Astrophysique de Marseille (LAM) during a 6-month period from September 2009 to March 2010. In general, it is a very complicated task to combine the above two stray light issues together in the simulation and design phase as it requires to consider the propagation inside the telescope of the light diffracted by the external occulter. Actually, the present literature only reports diffraction calculations performed for simple occulting systems (i.e., two disks and serrated disk). A more pragmatic approach, also driven by the tight schedule of the STARTIGER program, is to separate the two contributions, and perform two different stray light analyses. This paper is dedicated to the description of both analyses: in particular, the first part is dedicated to the evaluation of the stray light inside the telescope, assuming a simple disk as occulter, and a preliminary baffle design is presented; the second part describes the investigation on the geometry of the external occulter, with a detailed description of the laboratory setup that has been designed and implemented to compare together several types of occulting systems.

Design Features of the Neutral Particle Diagnostic System for the ITER Tokamak

NASA Astrophysics Data System (ADS)

Petrov, S. Ya.; Afanasyev, V. I.; Melnik, A. D.; Mironov, M. I.; Navolotsky, A. S.; Nesenevich, V. G.; Petrov, M. P.; Chernyshev, F. V.; Kedrov, I. V.; Kuzmin, E. G.; Lyublin, B. V.; Kozlovski, S. S.; Mokeev, A. N.

2017-12-01

The control of the deuterium-tritium (DT) fuel isotopic ratio has to ensure the best performance of the ITER thermonuclear fusion reactor. The diagnostic system described in this paper allows the measurement of this ratio analyzing the hydrogen isotope fluxes (performing neutral particle analysis (NPA)). The development and supply of the NPA diagnostics for ITER was delegated to the Russian Federation. The diagnostics is being developed at the Ioffe Institute. The system consists of two analyzers, viz., LENPA (Low Energy Neutral Particle Analyzer) with 10-200 keV energy range and HENPA (High Energy Neutral Particle Analyzer) with 0.1-4.0MeV energy range. Simultaneous operation of both analyzers in different energy ranges enables researchers to measure the DT fuel ratio both in the central burning plasma (thermonuclear burn zone) and at the edge as well. When developing the diagnostic complex, it was necessary to account for the impact of several factors: high levels of neutron and gamma radiation, the direct vacuum connection to the ITER vessel, implying high tritium containment, strict requirements on reliability of all units and mechanisms, and the limited space available for accommodation of the diagnostic hardware at the ITER tokamak. The paper describes the design of the diagnostic complex and the engineering solutions that make it possible to conduct measurements under tokamak reactor conditions. The proposed engineering solutions provide a safe—with respect to thermal and mechanical loads—common vacuum channel for hydrogen isotope atoms to pass to the analyzers; ensure efficient shielding of the analyzers from the ITER stray magnetic field (up to 1 kG); provide the remote control of the NPA diagnostic complex, in particular, connection/disconnection of the NPA vacuum beamline from the ITER vessel; meet the ITER radiation safety requirements; and ensure measurements of the fuel isotopic ratio under high levels of neutron and gamma radiation.

What Do They Have That We Don't Have? Local Libraries and Distance Students: Why Do Students Stray and Can We Get Them Back?

ERIC Educational Resources Information Center

Behr, Michele; LaDell-Thomas, Julie

2014-01-01

A significant number of distance students report they "stray" from their home universities by using local libraries, despite the fact that distance education librarians work hard to provide customized resources and services tailored to their programs and needs. Are public libraries and special libraries able to meet the research needs of…

A rare case of acute toxoplasmosis in a stray dog due to infection of T. gondii clonal type I: public health concern in urban settings with stray animals?

PubMed

Migliore, Sergio; La Marca, Salvatore; Stabile, Cristian; Di Marco Lo Presti, Vincenzo; Vitale, Maria

2017-08-17

Typing of Toxoplasma gondii strains is important in epidemiological surveys, to understand the distribution and virulence of different clones of the parasite among human and animal populations. Stray dogs can be consider sentinel animals for contaminated environments playing an important but probably under- evaluated role in the epidemiology of T. gondii. We reported a rare case of acute toxoplasmosis in a stray dog due to clonal type I infection. The clonal type I, sporadic in Europe, is frequently associated with severe toxoplasmosis in humans and the control of its circulation is particularly relevant for public health. The symptomatology suggested a potential infection with the high similar parasite Neospora caninum but differential diagnosis showed that only T. gondii was involved highlighting the importance of multiple diagnostic methods beyond the clinical signs. A female stray dog approximately six-month of age presented muscular atrophy of the femoral region and hyperextension of hind limbs. Body condition score (BCS) was 20% below ideal weight, ribs had almost no fat and the sensor state was depressed. Haematological values were normal and the dog did not show any neurological abnormalities. Serological analysis showed a positive response for T. gondii immunoglobulin G (IgG) antibodies and exclude N. caninum infection. To confirm T. gondii infection, a muscle biopsy was performed and genomic DNA was extracted. PCR analysis resulted positive to T. gondii and strain genotyping reveals clonal type I infection. The dog recovered after 4 weeks of treatment with clindamycin hydrochloride and aquatic physiotherapy. Our study reports a rare and severe case of T. gondii clonal type I infection in a stray dog feeding in garbage containers. The data confirm the importance of an in vivo early diagnosis for toxoplasmosis in dog. Clinical signs are often related to specific T. gondii genotype and parasite genotyping is important in the epidemiological survey of toxoplasmosis in public health. The detection of parasitic DNA in the tissue could be an useful diagnostic method in facilitating early treatment of the disease, which is important for a timely clinical recovery.

SU-E-T-598: Parametric Equation for Quick and Reliable Estimate of Stray Neutron Doses in Proton Therapy and Application for Intracranial Tumor Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonfrate, A; Farah, J; Sayah, R

2015-06-15

Purpose: Development of a parametric equation suitable for a daily use in routine clinic to provide estimates of stray neutron doses in proton therapy. Methods: Monte Carlo (MC) calculations using the UF-NCI 1-year-old phantom were exercised to determine the variation of stray neutron doses as a function of irradiation parameters while performing intracranial treatments. This was done by individually changing the proton beam energy, modulation width, collimator aperture and thickness, compensator thickness and the air gap size while their impact on neutron doses were put into a single equation. The variation of neutron doses with distance from the target volumemore » was also included in it. Then, a first step consisted in establishing the fitting coefficients by using 221 learning data which were neutron absorbed doses obtained with MC simulations while a second step consisted in validating the final equation. Results: The variation of stray neutron doses with irradiation parameters were fitted with linear, polynomial, etc. model while a power-law model was used to fit the variation of stray neutron doses with the distance from the target volume. The parametric equation fitted well MC simulations while establishing fitting coefficients as the discrepancies on the estimate of neutron absorbed doses were within 10%. The discrepancy can reach ∼25% for the bladder, the farthest organ from the target volume. Finally, the validation showed results in compliance with MC calculations since the discrepancies were also within 10% for head-and-neck and thoracic organs while they can reach ∼25%, again for pelvic organs. Conclusion: The parametric equation presents promising results and will be validated for other target sites as well as other facilities to go towards a universal method.« less

Gastrointestinal Helminths and Ectoparasites in the Stray Cats (Felidae: Felis catus) of Ahar Municipality, Northwestern Iran

PubMed Central

YAKHCHALI, Mohammad; HAJIPOUR, Nasser; MALEKZADEH-VIAYEH, Reza; ESMAEILNEJAD, Bijan; NEMATI-HARAVANI, Taher; FATHOLLAHZADEH, Mohammad; JAFARI, Rasool

2017-01-01

Background: The stray cats are considered as the sources of emerging humans and domestic livestock pathogens and the zoonoses of public health importance. The present study was aimed to elucidate intestinal helminth infections and infestation with ectoparasites of the stray cats of Ahar City, northwestern Iran. Methods: Totally, 51 stray cats were randomly trapped from different parts of the city between Mar and Nov 2013. The cats were assessed for ectoparasites by hair brushing, skin scraping, acetate tape preparation and othic swabs. They were euthanized and inspected for helminths infection. Results: Overall prevalence of helminths and flea were 44/51 (86.3%) and 31/51 (60.78%), respectively. The infection rates were significantly different among different age groups (P<0.05). Of the 282 isolated helminths, three species of nematodes (Toxocara cati (86.3%), T. leonina (11.77%), Ancylostoma tubaeforme (5.9%)) and four species of cestodes (Taenia taeniaeformis (64.7%), Mesocestoides lineatus (49.02%), Dipylidium caninum (29.41%), T. hydatigena (19.6%)) were identified. The predominant infectious helminths in all the infected cats were T. cati (86.3% with egg per gram of feces 27.75±9). Of the 270 collected fleas, two species of Ctenocephalides felis (80%) and C. canis (20%) were notably frequent in the cats aged 2-3-year-old. The average number of fleas per each infected cat was recorded as 5.29, with no incidence of cross-infection. Conclusion: The results indicated the high rate of helminths infections and flea infestation in the urban stray cats of which Toxocara cati and Ctenocephalides felis may play important roles as zoonotic agents in the region. PMID:28761492

Gastrointestinal and ectoparasites from urban stray dogs in Fortaleza (Brazil): high infection risk for humans?

PubMed

Klimpel, Sven; Heukelbach, Jörg; Pothmann, David; Rückert, Sonja

2010-08-01

Dogs are important definite or reservoir hosts for zoonotic parasites. However, only few studies on the prevalence of intestinal parasites in urban areas in Brazil are available. We performed a comprehensive study on parasites of stray dogs in a Brazilian metropolitan area. We included 46 stray dogs caught in the urban areas of Fortaleza (northeast Brazil). After euthanization, dogs were autopsied. Ectoparasites were collected, and the intestinal content of dogs were examined for the presence of parasites. Faecal samples were collected and analysed using merthiolate iodine formaldehyde concentration method. A total of nine different parasite species were found, including five endoparasite (one protozoan, one cestode and three nematode species) and four ectoparasite species (two flea, one louse and one tick species). In the intestinal content, 3,162 specimens of four helminth species were found: Ancylostoma caninum (prevalence, 95.7%), Dipylidium caninum (45.7%), Toxocara canis (8.7%) and Trichuris vulpis (4.3%). A total of 394 ectoparasite specimens were identified, including Rhipicephalus sanguineus (prevalence, 100.0%), Heterodoxus spiniger (67.4%), Ctenocephalides canis (39.1%) and Ctenocephalides felis (17.4%). In the faeces, intestinal parasites were detected in 38 stray dogs (82.6%), including oocysts of Giardia sp. (2.2%) and eggs of the nematode A. caninum (82.6%). Neither eggs nor larval stages of D. caninum, T. canis or T. vulpis were detected in dog faeces. Sensitivity of faecal examination for A. caninum was 86.4% (95% confidence interval, 72.0-94.3) but zero percentage for the other intestinal helminth species. Our data show that stray dogs in northeast Brazil carry a multitude of zoonotic ecto- and endoparasites, posing a considerable risk for humans. With the exception of A. caninum, sensitivity of faecal examination was negligible.

Effects of shielding coatings on the anode shaping process during counter-rotating electrochemical machining

NASA Astrophysics Data System (ADS)

Wang, Dengyong; Zhu, Zengwei; Wang, Ningfeng; Zhu, Di

2016-09-01

Electrochemical machining (ECM) has been widely used in the aerospace, automotive, defense and medical industries for its many advantages over traditional machining methods. However, the machining accuracy in ECM is to a great extent limited by the stray corrosion of the unwanted material removal. Many attempts have been made to improve the ECM accuracy, such as the use of a pulse power, passivating electrolytes and auxiliary electrodes. However, they are sometimes insufficient for the reduction of the stray removal and have their limitations in many cases. To solve the stray corrosion problem in CRECM, insulating and conductive coatings are respectively used. The different implement processes of the two kinds of coatings are introduced. The effects of the two kinds of shielding coatings on the anode shaping process are investigated. Numerical simulations and experiments are conducted for the comparison of the two coatings. The simulation and experimental results show that both the two kinds of coatings are valid for the reduction of stray corrosion on the top surface of the convex structure. However, for insulating coating, the convex sidewall becomes concave when the height of the convex structure is over 1.26 mm. In addition, it is easy to peel off by the high-speed electrolyte. In contrast, the conductive coating has a strong adhesion, and can be well reserved during the whole machining process. The convex structure fabricated by using a conductive iron coating layer presents a favorable sidewall profile. It is concluded that the conductive coating is more effective for the improvement of the machining quality in CRECM. The proposed shielding coatings can also be employed to reduce the stray corrosion in other schemes of ECM.

How to manipulate magnetic states of antiferromagnets

NASA Astrophysics Data System (ADS)

Song, Cheng; You, Yunfeng; Chen, Xianzhe; Zhou, Xiaofeng; Wang, Yuyan; Pan, Feng

2018-03-01

Antiferromagnetic materials, which have drawn considerable attention recently, have fascinating features: they are robust against perturbation, produce no stray fields, and exhibit ultrafast dynamics. Discerning how to efficiently manipulate the magnetic state of an antiferromagnet is key to the development of antiferromagnetic spintronics. In this review, we introduce four main methods (magnetic, strain, electrical, and optical) to mediate the magnetic states and elaborate on intrinsic origins of different antiferromagnetic materials. Magnetic control includes a strong magnetic field, exchange bias, and field cooling, which are traditional and basic. Strain control involves the magnetic anisotropy effect or metamagnetic transition. Electrical control can be divided into two parts, electric field and electric current, both of which are convenient for practical applications. Optical control includes thermal and electronic excitation, an inertia-driven mechanism, and terahertz laser control, with the potential for ultrafast antiferromagnetic manipulation. This review sheds light on effective usage of antiferromagnets and provides a new perspective on antiferromagnetic spintronics.

Symmetric modular torsatron

DOEpatents

Rome, J.A.; Harris, J.H.

1984-01-01

A fusion reactor device is provided in which the magnetic fields for plasma confinement in a toroidal configuration is produced by a plurality of symmetrical modular coils arranged to form a symmetric modular torsatron referred to as a symmotron. Each of the identical modular coils is helically deformed and comprise one field period of the torsatron. Helical segments of each coil are connected by means of toroidally directed windbacks which may also provide part of the vertical field required for positioning the plasma. The stray fields of the windback segments may be compensated by toroidal coils. A variety of magnetic confinement flux surface configurations may be produced by proper modulation of the winding pitch of the helical segments of the coils, as in a conventional torsatron, winding the helix on a noncircular cross section and varying the poloidal and radial location of the windbacks and the compensating toroidal ring coils.

Stray Light Analysis

NASA Technical Reports Server (NTRS)

1997-01-01

Based on a Small Business Innovation Research contract from the Jet Propulsion Laboratory, TracePro is state-of-the-art interactive software created by Lambda Research Corporation to detect stray light in optical systems. An image can be ruined by incidental light in an optical system. To maintain image excellence from an optical system, stray light must be detected and eliminated. TracePro accounts for absorption, specular reflection and refraction, scattering and aperture diffraction of light. Output from the software consists of spatial irradiance plots and angular radiance plots. Results can be viewed as contour maps or as ray histories in tabular form. TracePro is adept at modeling solids such as lenses, baffles, light pipes, integrating spheres, non-imaging concentrators, and complete illumination systems. The firm's customer base includes Lockheed Martin, Samsung Electronics and other manufacturing, optical, aerospace, and educational companies worldwide.

A Survey of Public Opinion on Cat (Felis catus) Predation and the Future Direction of Cat Management in New Zealand.

PubMed

Walker, Jessica K; Bruce, Stephanie J; Dale, Arnja R

2017-07-03

Cat predation is a prominent issue in New Zealand that provokes strong and opposing views. We explored, via 1011 face-to-face questionnaires, public opinion on (a) support for a National Cat Management Strategy (78% support); (b) concern regarding predation of wildlife by owned and un-owned cats (managed stray, unmanaged stray, and feral cats); (c) the acceptability of management techniques for owned cats; and (d) the acceptability of population management techniques for un-owned cats. The highest concern was expressed regarding the predation of non-native and native wildlife by feral cats (60 and 86% repectively), followed by unmanaged stray cats (59 and 86% respectively), managed stray cats (54 and 82% respectively), and finally owned cats (38 and 69% repectively). Limits to the number of cats owned and cat restriction zones received high levels of support (>65%), and compulsory microchipping, Council registration, and de-sexing were supported by the majority (>58%). Public support of population control methods for unowned cats was explored, and the influence of participant demographic variables on responses is described. These findings provide insight into public opinion regarding the management of cats in New Zealand, which should be considered during the development of legislation in this area.

An assessment of the stray-light in 25 years Dobson total ozone data at Athens, Greece

NASA Astrophysics Data System (ADS)

Christodoulakis, J.; Varotsos, C.; Cracknell, A. P.; Tzanis, C.; Neofytos, A.

2015-02-01

In this study, we investigated the susceptibility of the Dobson spectrophotometer No. 118 to stray-light interference. In this regard, a series of total ozone content measurements were carried out in Athens, Greece for airmass values (μ) extending up to μ = 5. The monochromatic-heterochromatic stray-light derived by Basher's model was used in order to evaluate the specific instrumental parameters which determine if this instrument suffers from this problem or not. The results obtained indicate that the Athens Dobson instrument appears to have an insignificant stray-light error. The comparison of the values of the same parameters measured 15 years ago with the present ones indicates the good maintenance of the Dobson spectrophotometer No. 118. This fact is of crucial importance because the variability of the daily total ozone observations collected by the Athens Dobson Station since 1989 has proved to be representative to the variability of the mean total ozone observed over the whole mid-latitude zone of the Northern Hemisphere. This stresses the point that the Athens total ozone station, being the unique Dobson station in south eastern Europe, may be assumed as a ground-truth station for the reliable conversion of the satellite radiance observations to total ozone measurements.

Potential Zoonotic Trematodes Recovered in Stray Cats from Kuwait Municipality, Kuwait

PubMed Central

El-Azazy, Osama Mohamed ElShfei; Abdou, Nadra-Elwgoud Mohamed Ibrahim; Khalil, Amal Iskander; Al-Batel, Maha Khaled; Majeed, Qais Abdulrazak Habeeb; Henedi, Adawia Abdul-Ruhman; Tahrani, Laila Mohamed Azad

2015-01-01

Stray cats are a common feature roaming the streets and alleys of Kuwait; they could be a source of parasites, including trematodes, that affect humans. A survey was conducted to identify feline trematodes and throw the light on their public health significance in Kuwait. Out of 240 stray cats trapped from different localities of Kuwait from June 2011 to May 2012, 59 (24.6%) were found to be infected with 14 species of trematodes. The most common were trematodes of the genus Heterophyes, particularly H. heterophyes and H. dispar that were found in respectively 15.8% and 10.8% of the cats examined. Other trematodes recorded, with lower prevalences, were Heterophyes nocens (2.9%), Haplorchis taichui (3.8%), Stictodora sawakinensis (2.1%), Stellantchasmus falcatus (1.6%), Echinochasmus japonicus (1.6%), and Mesostephanus dottrensi (1.3%). Centrocestus cuspidatus, Galactosomum fregatae, Ascocotyle sp., Mesostephanus appendiculatus, Haplorchis yokogawai, and Pygidiopsis genata showed the lowest prevalence (0.4%) and intensity. The majority of the trematodes are recorded for the first time in Kuwait and even in the Gulf region. The study reveals that stray cats are good indicators of fish-borne trematodes in the environment. As all trematodes recovered are zoonotic, their significance to public health should be considred. PMID:26174821

Development of an experimental system for characterization of high-temperature superconductors cooled by liquid hydrogen under the external magnetic field

NASA Astrophysics Data System (ADS)

Tatsumoto, H.; Shirai, Y.; Shiotsu, M.; Naruo, Y.; Kobayashi, H.; Inatani, Y.

2014-05-01

An experimental system has been developed to investigate electro-magnetic properties of high-Tc superconductors cooled by liquid hydrogen under the external magnetic field of up to 7 T. A LH2 cryostat is concentrically mounted on the inside of a LHe cryostat to cool a NbTi superconducting magnet. The experimental system is installed in an explosion-proof room. Explosion proof electrical devices are used and current leads are covered with an enclosure filled with nitrogen gas. A remote control system has been developed. Furthermore, the effects of stray magnetic field on the existing and the new devices are investigated and electro-magnetic shielding panels and enclosure made of iron were designed. It is confirmed through the cryogenic test that the experimental system meets the design requirements.

SU-E-J-200: Operation of An Electron Accelerator On An Integrated MR-Linac System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harasimowicz, J; Roberts, D; Shinton, I

2015-06-15

Purpose: An integrated MRI guided radiotherapy system poses a challenge of operating a linear accelerator in the presence of a magnetic field as the magnetic force acting on the electrons could Result in radiation source displacement and subsequent reduction of dose output. It was the purpose of this work to test the performance of a linac in the presence of a 1.5T MRI system. Methods: The first experimental MRI guided radiotherapy system at UMC-Utrecht consisting of an Elekta linac rotating around a 1.5T Magnex magnet was examined. A passive magnetic shield was simulated, designed and installed to reduce the influencemore » of the MRI magnet stray field on the electron beamline. The B field inside the shield was measured as a function of gantry angle and measurements of dose rate constancy upon gantry rotation were performed. Results: The magnitude of the magnetic field on the electron beam path without the shield was as high as 70G. It varied by up to 15G with gantry rotation due to the presence of metal beams in the bunker floor which resulted in dose output drop of up to 70% at certain gantry angles. With the prototype shield, field magnitude was reduced to well below 0.5G everywhere along the electron beam path. Field variation with gantry rotation was decreased to below 0.2G and enabled dose output of the linac to be recovered at all gantry angles. The homogeneity of the field inside the MRI magnet has not been compromised. Conclusion: It was demonstrated that the influence of the 1.5T magnet and the bunker design on the linac operation has been minimised. The performance will be further improved on the Elekta Atlantic system which incorporates a newly developed and optimised Philips magnet design and bunker construction. J Harasimowicz, D Roberts, I Shinton and S Sund are employed by Elekta Limited Crawley, H Wang and M Zhong are employed by Elekta Beijing Medical Systems Co. Ltd., J Overweg is employed by Philips Technologie GmbH Forschungslaboratorien.« less

Self-healing patterns in ferromagnetic-superconducting hybrids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlasko-Vlasov, V. K.; Palacious, E.; Rosenmann, D.

We study magnetic flux dynamic effects in a superconducting bridge with thin soft magnetic stripes placed either on top or under the bridge. Voltage-current (VI) measurements reveal that the edges of magnetic stripes oriented transvers or along the bridge introduce channels or barriers for vortex motion, resulting in the decrease or increase of the critical current, respectively. We demonstrate a remarkable self-healing effect whereby the magnetic pinning strength for the longitudinal stripes increases with current. The self-field of the current polarizes the magnetic stripes along their width, which enhances the stray fields at their edges and creates a dynamic vortexmore » pinning landscape to impede vortex flow. Our results highlight new strategies to engineer adaptive pinning topologies in superconducting-ferromagnetic hybrids.« less

Piezoelectric and Magnetoelectric Thick Films for Fabricating Power Sources in Wireless Sensor Nodes

PubMed Central

Priya, Shashank; Ryu, Jungho; Park, Chee-Sung; Oliver, Josiah; Choi, Jong-Jin; Park, Dong-Soo

2009-01-01

In this manuscript, we review the progress made in the synthesis of thick film-based piezoelectric and magnetoelectric structures for harvesting energy from mechanical vibrations and magnetic field. Piezoelectric compositions in the system Pb(Zr,Ti)O3–Pb(Zn1/3Nb2/3)O3 (PZNT) have shown promise for providing enhanced efficiency due to higher energy density and thus form the base of transducers designed for capturing the mechanical energy. Laminate structures of PZNT with magnetostrictive ferrite materials provide large magnitudes of magnetoelectric coupling and are being targeted to capture the stray magnetic field energy. We analyze the models used to predict the performance of the energy harvesters and present a full system description. PMID:22454590

Fixing Stellarator Magnetic Surfaces

NASA Astrophysics Data System (ADS)

Hanson, James D.

1999-11-01

Magnetic surfaces are a perennial issue for stellarators. The design heuristic of finding a magnetic field with zero perpendicular component on a specified outer surface often yields inner magnetic surfaces with very small resonant islands. However, magnetic fields in the laboratory are not design fields. Island-causing errors can arise from coil placement errors, stray external fields, and design inadequacies such as ignoring coil leads and incomplete characterization of current distributions within the coil pack. The problem addressed is how to eliminate such error-caused islands. I take a perturbation approach, where the zero order field is assumed to have good magnetic surfaces, and comes from a VMEC equilibrium. The perturbation field consists of error and correction pieces. The error correction method is to determine the correction field so that the sum of the error and correction fields gives zero island size at specified rational surfaces. It is particularly important to correctly calculate the island size for a given perturbation field. The method works well with many correction knobs, and a Singular Value Decomposition (SVD) technique is used to determine minimal corrections necessary to eliminate islands.

The application of magnetic resonance microimaging to the visible light curing of dental resins. 3. Stray-field nuclear magnetic resonance imaging (STRAFI).

PubMed

Lloyd, C H; Scrimgeour, S N; Lane, D M; Hunter, G; McDonald, P J

2001-09-01

To investigate the application of stray-field nuclear magnetic resonance imaging (STRAFI) to the visible light curing of dental restorative materials. STRAFI can overcome peak broadening associated with the conventional magnetic resonance microimaging (MRM) of glassy polymers, and has the potential to image dental restorative resins at both low and high degrees of conversion. Cylindrical composite specimens were light-cured from one end to produce some that were fully cured throughout their length and others that were fully cured at one end and uncured at the other. A one-dimensional probe was used to measure the magnetisation in 40 microm thick slices at 100 microm intervals along the length of the specimen. A quadrature pulse sequence was applied and the magnetisation decay recorded in a train of eight echoes. A value for T(2) could be obtained only for the polymer (59+/-16 microms), therefore the echoes were summed to give an approximate indication of the degree of conversion. The echo sum for the monomer was significantly higher than that for the polymer. Differences in composite shade and cure time produced changes in the cure profiles. STRAFI produced measurements for both monomer and polymer in all stages of conversion that allowed cure profiles to be produced. Summing the decay echoes produced a qualitative measure of the condition of the material in the selected slice. The same data can be used to calculate T(2), a quantitative parameter. This first investigation has demonstrated that STRAFI is well suited to polymerisation studies.

Canine transmissible venereal tumour: a review.

PubMed

Ganguly, B; Das, U; Das, A K

2016-03-01

Canine transmissible venereal tumour (CTVT) is a contagious venereal tumour of dogs, commonly observed in dogs that are in close contact with one another, or in stray and wild dogs that exhibit unrestrained sexual activity. CTVT represents a unique, naturally transmissible, contagious tumour, where the mutated tumour cell itself is the causative agent and perpetuates as a parasitic allograft in the host. Clinical history, signalment and cytological features are often obvious for establishing a diagnosis though biopsy and histological examination may be needed in atypical cases. Most cases are curable with three intravenous injections of vincristine sulphate at weekly intervals. The role of stray and wild dogs makes the disease difficult to control and necessitates sustained animal birth control in stray dogs along with prompt therapy of the affected dogs. This review captures the manifold developments in different areas embracing this fascinating tumour, including its biology, diagnosis and therapeutic alternatives. © 2013 John Wiley & Sons Ltd.

Stray cats are more frequently infected with zoonotic protists than pet cats.

PubMed

Kvac, Martin; Hofmannova, Lada; Ortega, Ynes; Holubova, Nikola; Horcickova, Michaela; Kicia, Marta; Hlaskova, Lenka; Kvetonova, Dana; Sak, Bohumil; McEvoy, John

2017-12-06

Faecal samples were collected from cats kept as pets (n = 120) and stray cats (n = 135) in Central Europe (Czech Republic, Poland and Slovakia) and screened for the presence of Cryptosporidium spp., Giardia intestinalis (Kunstler, 1882), Encephalitozoon spp. and Enterocytozoon bieneusi Desportes, Le Charpentier, Galian, Bernard, Cochand-Priollet, Lavergne, Ravisse et Modigliani, 1985 by PCR analysis of the small-subunit of rRNA (Cryptosporidium spp. and G. intestinalis) and ITS (microsporidia) genes. Sequence analysis of targeted genes revealed the presence of C. felis Iseki, 1979, G. intestinalis assemblage F, E. cuniculi Levaditi, Nicolau et Schoen, 1923 genotype II, and E. bieneusi genotype D. There was no correlation between the occurrence of detected parasites and sex, presence of diarrhoea or drug treatment (drug containing pyrantel and praziquantel). Compared to pet cats (7%), stray cats (30%) were statistically more frequently infected with protist parasites and overall may present a greater risk to human health.

Bartonella and Toxoplasma Infections in Stray Cats from Iraq

PubMed Central

Switzer, Alexandra D.; McMillan-Cole, Audrey C.; Kasten, Rickie W.; Stuckey, Matthew J.; Kass, Philip H.; Chomel, Bruno B.

2013-01-01

Because of overpopulation, stray/feral cats were captured on military bases in Iraq as part of the US Army Zoonotic Disease Surveillance Program. Blood samples were collected from 207 cats, mainly in Baghdad but also in North and West Iraq, to determine the prevalence of Bartonella and Toxoplasma infections. Nine (4.3%) cats, all from Baghdad, were bacteremic with B. henselae type I. Seroprevalence was 30.4% for T. gondii, 15% for B. henselae, and 12.6% for B. clarridgeiae. Differences in Bartonella prevalence by location were statistically significant, because most of the seropositive cats were from Baghdad. There was no association between T. gondii seropositivity and either of the two Bartonella species surveyed. This report is the first report on the prevalence of Bartonella and T. gondii among stray cats in Iraq, which allows for better evaluation of the zoonotic risk potential to the Iraqi people and deployed military personnel by feral cat colonies. PMID:24062480

Genital mycoplasmas of healthy bitches.

PubMed

Maksimović, Zinka; Maksimović, Alan; Halilbašić, Anis; Rifatbegović, Maid

2018-05-01

Little is known about the presence of mycoplasmas in the genital tracts of domestic and stray bitches or in the vaginas of ovariohysterectomized (OHE) bitches. Moreover, to our knowledge, there has been no research to investigate the presence of canine vaginal mycoplasmas during the different stages of the reproductive cycle. We investigated the occurrence of mycoplasmas in the vaginas of healthy domestic and stray intact bitches, to correlate their presence with specific stages of the reproductive cycle, and to compare them with those in OHE bitches. We also investigated the presence of uterine mycoplasmas. Mycoplasmas were isolated from 41 of 122 vaginal swabs (34%) from domestic (27%) and stray (39%) bitches. Mycoplasma canis was the most commonly identified species ( n = 26; 63%), and was detected in both intact (60%) and OHE (73%) bitches. Mycoplasma isolates from the vaginas of healthy bitches did not vary during the various stages of the estrous cycle. Mycoplasmas were not detected in uterine samples.

Stray light suppression in the Goddard IRAM 2-Millimeter Observer (GISMO)

NASA Astrophysics Data System (ADS)

Sharp, E. H.; Benford, D. J.; Fixsen, D. J.; Moseley, S. H.; Staguhn, J. G.; Wollack, E. J.

2012-09-01

The Goddard-IRAM Superconducting 2 Millimeter Observer (GISMO) is an 8x16 Transition Edge Sensor (TES) array of bolometers built as a pathfinder for TES detector development efforts at NASA Goddard Space Flight Center. GISMO has been used annually at the Institut de Radioastronomie Millimétrique (IRAM) 30 meter telescope since 2007 under engineering time and was opened in the spring of 2012 to the general astronomical community. The spring deployment provided an opportunity to modify elements of the room temperature optics before moving the instrument to its new permanent position in the telescope receiver cabin. This allowed for the possibility to extend the cryostat, introduce improved cold baffling and thus further optimize the stray light performance for final astronomical use of the instrument, which has been completed and validated. We will demonstrate and discuss several of the methods used to quantify and limit the influence of stray light in the GISMO camera.

Stray Light Suppression in the Goddard IRAM 2-Millimeter Observer (GISMO)

NASA Technical Reports Server (NTRS)

Sharp, E. H.; Benford, D. J.; Fixsen, D. J.; Moseley, S. H.; Staguhn, J. G.; Wollack, E. J.

2012-01-01

The Goddard-IRAM Superconducting 2 Millimeter Observer (GISMO) is an 8xl6 Transition Edge Sensor (TES) array of bolometers built as a pathfinder for TES detector development efforts at NASA Goddard Space Flight Center. GISMO has been used annually at the Institut de Radioastronomie Millimetrique (IRAM) 30 meter telescope since 2007 under engineering time and was opened in the spring of 2012 to the general astronomical community. The spring deployment provided an opportunity to modify elements of the room temperature optics before moving the instrument to its new permanent position in the telescope receiver cabin. This allowed for the possibility to extend the cryostat, introduce improved cold baffling and thus further optimize the stray light performance for final astronomical use of the instrument, which has been completed and validated. We will demonstrate and discuss several of the methods used to quantify and limit the influence of stray light in the GISMO camera.

A Survey Study on Gastrointestinal Parasites of Stray Cats in Northern Region of Nile Delta, Egypt

PubMed Central

Khalafalla, Reda E.

2011-01-01

A survey study on gastrointestinal parasites in 113 faecal samples from stray cats collected randomly from Kafrelsheikh province, northern region of Nile delta of Egypt; was conducted in the period between January and May 2010. The overall prevalence was 91%. The results of this study reported seven helminth species: Toxocara cati (9%), Ancylostoma tubaeforme (4%), Toxascaris leonina (5%), Dipylidium caninum (5%), Capillaria spp. (3%), Taenia taeniformis (22%) and Heterophyes heterophyes (3%), four protozoal species: Toxoplasma gondii (9%), Sarcocyst spp. (1%), Isospora spp. (2%) and Giardia spp. (2%) and two arthropod species; Linguatula serrata (2%) and mites eggs (13%). The overall prevalence of intestinal parasites may continue to rise due to lack of functional veterinary clinics for cat care in Egypt. Therefore, there is a need to plan adequate control programs to diagnose, treat and control gastrointestinal parasites of companion as well as stray cats in the region. PMID:21760884

Transparent Flexible Active Faraday Cage Enables In Vivo Capacitance Measurement in Assembled Microsensor.

PubMed

Ahmadi, Mahdi; Rajamani, Rajesh; Sezen, Serdar

2017-10-01

Capacitive micro-sensors such as accelerometers, gyroscopes and pressure sensors are increasingly used in the modern electronic world. However, the in vivo use of capacitive sensing for measurement of pressure or other variables inside a human body suffers from significant errors due to stray capacitance. This paper proposes a solution consisting of a transparent thin flexible Faraday cage that surrounds the sensor. By supplying the active sensing voltage simultaneously to the deformable electrode of the capacitive sensor and to the Faraday cage, the stray capacitance during in vivo measurements can be largely eliminated. Due to the transparency of the Faraday cage, the top and bottom portions of a capacitive sensor can be accurately aligned and assembled together. Experimental results presented in the paper show that stray capacitance is reduced by a factor of 10 by the Faraday cage, when the sensor is subjected to a full immersion in water.

Broadband notch filter design for millimeter-wave plasma diagnostics.

PubMed

Furtula, V; Michelsen, P K; Leipold, F; Salewski, M; Korsholm, S B; Meo, F; Nielsen, S K; Stejner, M; Moseev, D; Johansen, T

2010-10-01

Notch filters are integrated in plasma diagnostic systems to protect millimeter-wave receivers from intensive stray radiation. Here we present a design of a notch filter with a center frequency of 140 GHz, a rejection bandwidth of ∼900 MHz, and a typical insertion loss below 2 dB in the passband of ±9 GHz. The design is based on a fundamental rectangular waveguide with eight cylindrical cavities coupled by T-junction apertures formed as thin slits. Parameters that affect the notch performance such as physical lengths and conductor materials are discussed. The excited resonance mode in the cylindrical cavities is the fundamental TE(11). The performance of the constructed filter is measured using a vector network analyzer monitoring a total bandwidth of 30 GHz. We compare the measurements with numerical simulations.

Measurements of the neutron dose equivalent for various radiation qualities, treatment machines and delivery techniques in radiation therapy

NASA Astrophysics Data System (ADS)

Hälg, R. A.; Besserer, J.; Boschung, M.; Mayer, S.; Lomax, A. J.; Schneider, U.

2014-05-01

In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small.

Measurements of the neutron dose equivalent for various radiation qualities, treatment machines and delivery techniques in radiation therapy.

PubMed

Hälg, R A; Besserer, J; Boschung, M; Mayer, S; Lomax, A J; Schneider, U

2014-05-21

In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small.

Shielded capacitive electrode

DOEpatents

Kireeff Covo, Michel

2013-07-09

A device is described, which is sensitive to electric fields, but is insensitive to stray electrons/ions and unlike a bare, exposed conductor, it measures capacitively coupled current while rejecting currents due to charged particle collected or emitted. A charged particle beam establishes an electric field inside the beam pipe. A grounded metallic box with an aperture is placed in a drift region near the beam tube radius. The produced electric field that crosses the aperture generates a fringe field that terminates in the back surface of the front of the box and induces an image charge. An electrode is placed inside the grounded box and near the aperture, where the fringe fields terminate, in order to couple with the beam. The electrode is negatively biased to suppress collection of electrons and is protected behind the front of the box, so the beam halo cannot directly hit the electrode and produce electrons. The measured signal shows the net potential (positive ion beam plus negative electrons) variation with time, as it shall be observed from the beam pipe wall.

Interlayer-coupled spin vortex pairs and their response to external magnetic fields

NASA Astrophysics Data System (ADS)

Wintz, Sebastian; Bunce, Christopher; Banholzer, Anja; Körner, Michael; Strache, Thomas; Mattheis, Roland; McCord, Jeffrey; Raabe, Jörg; Quitmann, Christoph; Erbe, Artur; Fassbender, Jürgen

2012-06-01

We report on the response of multilayer spin textures to static magnetic fields. Coupled magnetic vortex pairs in trilayer elements (ferromagnetic/nonmagnetic/ferromagnetic) are imaged directly by means of layer-selective magnetic x-ray microscopy. We observe two different circulation configurations with parallel and opposing senses of magnetization rotation at remanence. Upon application of a field, all of the vortex pairs investigated react with a displacement of their cores. For purely dipolar coupled pairs, the individual core displacements are similar to those of an isolated single-layer vortex, but also a noticeable effect of the mutual stray fields is detected. Vortex pairs that are linked by an additional interlayer exchange coupling (IEC), which is either ferromagnetic or antiferromagnetic, mainly exhibit a layer-congruent response. We find that, apart from a possible decoupling at higher fields, these strict IEC vortex pairs can be described by a single-layer model with effective material parameters. This result implies the possibility to design multilayer spin structures with arbitrary effective magnetization.

Stray energy transfer during endoscopy.

PubMed

Jones, Edward L; Madani, Amin; Overbey, Douglas M; Kiourti, Asimina; Bojja-Venkatakrishnan, Satheesh; Mikami, Dean J; Hazey, Jeffrey W; Arcomano, Todd R; Robinson, Thomas N

2017-10-01

Endoscopy is the standard tool for the evaluation and treatment of gastrointestinal disorders. While the risk of complication is low, the use of energy devices can increase complications by 100-fold. The mechanism of increased injury and presence of stray energy is unknown. The purpose of the study was to determine if stray energy transfer occurs during endoscopy and if so, to define strategies to minimize the risk of energy complications. A gastroscope was introduced into the stomach of an anesthetized pig. A monopolar generator delivered energy for 5 s to a snare without contacting tissue or the endoscope itself. The endoscope tip orientation, energy device type, power level, energy mode, and generator type were varied to mimic in vivo use. The primary outcome (stray current) was quantified as the change in tissue temperature (°C) from baseline at the tissue closest to the tip of the endoscope. Data were reported as mean ± standard deviation. Using the 60 W coag mode while changing the orientation of the endoscope tip, tissue temperature increased by 12.1 ± 3.5 °C nearest the camera lens (p < 0.001 vs. all others), 2.1 ± 0.8 °C nearest the light lens, and 1.7 ± 0.4 °C nearest the working channel. Measuring temperature at the camera lens, reducing power to 30 W (9.5 ± 0.8 °C) and 15 W (8.0 ± 0.8 °C) decreased stray energy transfer (p = 0.04 and p = 0.002, respectively) as did utilizing the low-voltage cut mode (6.6 ± 0.5 °C, p < 0.001). An impedance-monitoring generator significantly decreased the energy transfer compared to a standard generator (1.5 ± 3.5 °C vs. 9.5 ± 0.8 °C, p < 0.001). Stray energy is transferred within the endoscope during the activation of common energy devices. This could result in post-polypectomy syndrome, bleeding, or perforation outside of the endoscopist's view. Decreasing the power, utilizing low-voltage modes and/or an impedance-monitoring generator can decrease the risk of complication.

Environmental contamination with Toxocara eggs: a quantitative approach to estimate the relative contributions of dogs, cats and foxes, and to assess the efficacy of advised interventions in dogs.

PubMed

Nijsse, Rolf; Mughini-Gras, Lapo; Wagenaar, Jaap A; Franssen, Frits; Ploeger, Harm W

2015-07-28

Environmental contamination with Toxocara eggs is considered the main source of human toxocariasis. The contribution of different groups of hosts to this contamination is largely unknown. Current deworming advices focus mainly on dogs. However, controversy exists about blind deworming regimens for >6-month-old dogs, as most of them do not actually shed Toxocara eggs. We aim to estimate the contribution of different non-juvenile hosts to the environmental Toxocara egg contamination and to assess the effects of different Toxocara-reducing interventions for dogs. A stochastic model was developed to quantify the relative contribution to the environmental contamination with Toxocara eggs of household dogs, household cats, stray cats, and foxes, all older than 6 months in areas with varying urbanization degrees. The model was built upon an existing model developed by Morgan et al. (2013). We used both original and published data on host density, prevalence and intensity of infection, coprophagic behaviour, faeces disposal by owners, and cats' outdoor access. Scenario analyses were performed to assess the expected reduction in dogs' egg output according to different deworming regimens and faeces clean-up compliances. Estimates referred to the Netherlands, a country free of stray dogs. Household dogs accounted for 39% of the overall egg output of >6-month-old hosts in the Netherlands, followed by stray cats (27%), household cats (19%), and foxes (15%). In urban areas, egg output was dominated by stray cats (81%). Intervention scenarios revealed that only with a high compliance (90%) to the four times a year deworming advice, dogs' contribution would drop from 39 to 28%. Alternatively, when 50% of owners would always remove their dogs' faeces, dogs' contribution would drop to 20%. Among final hosts of Toxocara older than 6 months, dogs are the main contributors to the environmental egg contamination, though cats in total (i.e. both owned and stray) transcend this contribution. A higher than expected compliance to deworming advice is necessary to reduce dogs' egg output meaningfully. Actions focusing solely on household dogs and cats are unlikely to sufficiently reduce environmental contamination with eggs, as stray cats and foxes are also important contributors.

Molecular and Serological Evidence of Leishmania Infection in Stray Dogs from Visceral Leishmaniasis-Endemic Areas of Bangladesh.

PubMed

Akter, Shirin; Alam, Mohammad Zahangir; Nakao, Ryo; Yasin, Golam; Kato, Hirotomo; Katakura, Ken

2016-10-05

Visceral leishmaniasis (VL), or kala-azar, is mainly caused by two closely related Leishmania species, Leishmania infantum and Leishmania donovani Leishmania infantum is responsible for zoonotic VL, with dogs as the main reservoir host in the Mediterranean, the Middle East, Asia, and South America. In the Indian subcontinent, VL is caused by L. donovani and is considered anthroponotic, although the only known vector, the sand fly, is zoophilic in nature. The role of domestic and stray dogs in VL transmission is still unclear in this area. We screened 50 stray dogs from VL-endemic areas of Bangladesh for serological and molecular evidence of Leishmania infection. We detected anti-Leishmania antibodies in six (12%) dog serum samples using rK39 immunochromatographic tests. We observed Leishmania kinetoplast DNA in 10 (20%) buffy coat DNA samples by real-time polymerase chain reaction (PCR), five of which were positive based on internal transcribed spacer 1-PCR. A sequencing analysis of the amplified products confirmed that the parasitic DNA was derived from L. donovani Our findings support the hypothesis that stray dogs are an animal reservoir for L. donovani in this endemic region. Further studies are required to determine the precise role of dogs in the epidemiology of VL in Bangladesh. © The American Society of Tropical Medicine and Hygiene.

An epidemiological survey on intestinal helminths of stray dogs in Mashhad, North-east of Iran.

PubMed

Emamapour, Seyed Rasoul; Borji, Hassan; Nagibi, Abolghasem

2015-06-01

This research was conducted to determine the prevalence of gastrointestinal helminths in stray dogs in the northeast of Iran, with special attention to those parasites that can be transmitted to human. In this experiment, a total of 72 adult and 18 juvenile stray dogs were collected and necropsied for the presence of helminth parasites from October 2011 to August 2012. The overall prevalence of gastrointestinal helminths was 86 % (95 % CI: 79.2-92.8 %). The observed helminths of the gastrointestinal tract were listed as follows: Toxocara canis (29 %), Toxascaris leonina (7 %), Ancylostoma caninum (2 %), Taenia hydatigena (43 %), Dipylidium caninum (39 %), Echinococcus granulosus (38 %), Mesocestoides lineatus (16 %), Taenia multiceps (11 %), Taenia ovis (3 %). There were no significant differences for the prevalence of gastrointestinal helminths between female (83.6 %) and male (89.7 %) and between young (89 %) and adult (72.2 %) animals. However, the prevalence of E. granulosus, T. hydatigena and D. caninum showed an increasing trend with increasing host age, significantly. Based on our data, it is important to point out the presence of zoonotic agents, namely E. granulosus and T. canis in stray dogs in the investigated area. Due to its impact on public health, appropriate control measures should be taken and it is recommended to determine the most appropriate preventive methods.

Prevalence of swine viral and bacterial pathogens in rodents and stray cats captured around pig farms in Korea.

PubMed

Truong, Quang Lam; Seo, Tae Won; Yoon, Byung-Il; Kim, Hyeon-Cheol; Han, Jeong Hee; Hahn, Tae-Wook

2013-12-30

In 2008, 102 rodents and 24 stray cats from the areas around 9 pig farms in northeast South Korea were used to determine the prevalence of the following selected swine pathogens: ten viral pathogens [porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), rotavirus, classical swine fever virus (CSFV), porcine circovirus type 2 (PCV2), encephalomyocarditis virus (EMCV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine parvovirus (PPV), pseudorabies virus (PRV) and Japanese encephalitis virus (JEV)] and four bacterial pathogens (Brucella, Leptospira, Salmonella and Lawsonia intracellularis). In total, 1,260 tissue samples from 102 rodents and 24 stray cats were examined by specific PCR and RT-PCR assays, including tissue samples of the brain, tonsils, lungs, heart, liver, kidneys, spleen, small intestine, large intestine and mesenteric lymph nodes. The percentages of PCR-positive rodents for the porcine pathogens were as follows: 63.7% for Leptospira, 39.2% for Brucella, 6.8% for Salmonella, 15.7% for L. intracellularis, 14.7% for PCV2 and 3.9% for EMCV. The percentages of PCR-positive stray cats for the swine pathogens were as follows: 62.5% for Leptospira, 25% for Brucella, 12.5% for Salmonella, 12.5% for L. intracellularis and 4.2% for PEDV. These results may be helpful for developing control measures to prevent the spread of infectious diseases of pigs.

Prevalence of zoonotic intestinal parasites in household and stray dogs in rural areas of Hamadan, Western Iran.

PubMed

Sardarian, K; Maghsood, A H; Ghiasian, S A; Zahirnia, A H

2015-06-01

Zoonotic parasitic infections are a major global public and veterinary health problem and widespread among dogs. The objective of this study was to assess the prevalence of intestinal parasites in stray and household dogs in the rural areas of Hamadan district. During 2012, 1,500 fresh fecal samples from 243 household and 1,257 stray dogs were examined by using direct wet mount, simple zinc sulfate flotation, and Lugol's solution staining. Of 1,500 dogs, 20.4% were positive for intestinal parasites. Helminthes eggs were more frequently found in fecal samples than protozoan cysts or trophozoites (15.9% vs. 4.5%, respectively). Toxocara canis was the most frequently detected parasite, with a prevalence of 6.3%, followed by Taenia/Echinococcus spp. (2.9%), Isospora spp. (2.7%), and Toxascaris leonina (2.6%). Helminthes and protozoa were significantly more prevalent in household dogs than in stray dogs (P<0.001). There were significant differences in the prevalence of Isospora spp., T. canis and D. caninum among three age groups (P<0.05). The wide range of isolated parasites indicated that people residing in this area are at risk of exposure to these potentially hazardous zoonotic pathogens. Mass education of the general population is highly recommended to increase awareness of the potential for horizontal transmission of these parasitic infections from dogs to humans.

Microstructural, Magnetic Anisotropy, and Magnetic Domain Structure Correlations in Epitaxial FePd Thin Films with Perpendicular Magnetic Anisotropy

NASA Technical Reports Server (NTRS)

Skuza, J. R.; Clavero, C.; Yang, K.; Wincheski, B.; Lukaszew, R. A.

2009-01-01

L1(sub 0)-ordered FePd epitaxial thin films were prepared using dc magnetron sputter deposition on MgO (001) substrates. The films were grown with varying thickness and degree of chemical order to investigate the interplay between the microstructure, magnetic anisotropy, and magnetic domain structure. The experimentally measured domain size/period and magnetic anisotropy in this high perpendicular anisotropy system were found to be correlated following the analytical energy model proposed by Kooy and Enz that considers a delicate balance between the domain wall energy and the demagnetizing stray field energy.

Partial Return Yoke for MICE Step IV and Final Step

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witte, Holger; Plate, Stephen; Berg, J.Scott

2015-06-01

This paper reports on the progress of the design and construction of a retro-fitted return yoke for the international Muon Ionization Cooling Experiment (MICE). MICE is a proof-of-principle experiment aiming to demonstrate ionization cooling experimentally. In earlier studies we outlined how a partial return yoke can be used to mitigate stray magnetic field in the experimental hall; we report on the progress of the construction of the partial return yoke for MICE Step IV. We also discuss an extension of the Partial Return Yoke for the final step of MICE; we show simulation results of the expected performance.

Partial return yoke for MICE step IV and final step

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witte, H.; Plate, S.; Berg, J. S.

2015-05-03

This paper reports on the progress of the design and construction of a retro-fitted return yoke for the international Muon Ionization Cooling Experiment (MICE). MICE is a proof-of-principle experiment aiming to demonstrate ionization cooling experimentally. In earlier studies we outlined how a partial return yoke can be used to mitigate stray magnetic field in the experimental hall; we report on the progress of the construction of the partial return yoke for MICE Step IV. We also discuss an extension of the Partial Return Yoke for the final step of MICE; we show simulation results of the expected performance.

Similarity of SABRE field dependence in chemically different substrates

NASA Astrophysics Data System (ADS)

Dücker, Eibe B.; Kuhn, Lars T.; Münnemann, Kerstin; Griesinger, Christian

2012-01-01

The Non-Hydrogenative Parahydrogen-Induced Polarization (NH-PHIP) technique, which is referred to as Signal Amplification by Reversible Exchange (SABRE), has been reported to be applicable to various substrates and catalysts. For more detailed studies, pyridine was mainly examined in the past. Here, we examined several pyrazole derivatives towards their amenability to this method using Crabtree's Catalyst, which is the polarization transfer catalyst that is best documented. Additionally, the dependence of the signal enhancement on the field strength, at which the polarization step takes place, was examined for pyridine and four different pyrazoles. To achieve this, the polarization step was performed at numerous previously determined magnetic fields in the stray field of the NMR spectrometer. The substrate dependence of the field dependence proved to be relatively small for the different pyrazoles and a strong correlation to the field dependence for pyridine was observed. Reducing the number of spins in the catalyst by deuteration leads to increased enhancement. This indicates that more work has to be invested in order to be able to reproduce the SABRE field dependence by simulations.

Processing of DMSP magnetic data and its use in geomagnetic field modeling

NASA Technical Reports Server (NTRS)

Ridgway, J. R.; Sabaka, T. J.; Chinn, D.; Langel, R. A.

1989-01-01

The DMSP F-7 satellite is an operational Air Force meteorological satellite which carried a magnetometer for geophysical measurements. The magnetometer was located within the body of the spacecraft in the presence of large spacecraft fields. In addition to stray magnetic fields, the data have inherent position and time inaccuracies. Algorithms were developed to identify and remove time varying magnetic field noise from the data. Techniques developed for Magsat were then modified and used to attempt determination of the spacecraft fields, of any rotation between the magnetometer axes and the spacecraft axes, and of any scale changes within the magnetometer itself. The corrected data were then used to attempt to model the geomagnetic field. This was done in combination with data from Magsat, from the standard magnetic observatories, from aeromagnetic and other survey data, and from DE-2 spacecraft field data. Future DMSP missions can be upgraded in terms of geomagnetic measurements by upgrading the time and position information furnished with the data, placing the magnetometer at the end of the boom, upgrading the attitude determination at the magnetometer, and increasing the accuracy of the magnetometer.

Prevalence, risk factors and genetic characterization of Toxoplasma gondii in sick pigs and stray cats in Jiangsu Province, eastern China.

PubMed

Hou, Zhao-Feng; Su, Shi-Jie; Liu, Dan-Dan; Wang, Le-le; Jia, Chuan-Li; Zhao, Zhen-Xing; Ma, Yi-Fei; Li, Qiao-Qiao; Xu, Jin-Jun; Tao, Jian-Ping

2018-06-01

Toxoplasma gondii is an obligate intracellular parasitic protozoan with a worldwide distribution. The parasites in edible tissues of pigs and oocysts from cats are the major sources of T. gondii infection in humans. However, there are no data from sick pigs in veterinary clinics or from stray cats in Jiangsu Province, eastern China. In total, biological samples from 141 sick pigs and 64 stray cats were collected from this region. The rate of T. gondii infection in sick pigs was 46.81% using a polymerase chain reaction (PCR), and the overall prevalence of toxoplasmosis in stray cats was 34.38% by PCR and an enzyme-linked immunosorbent assay (ELISA). T. gondii was significantly more prevalent in lungs and heart than in liver and spleen (P < 0.05). Age and geographic region were considered to be the main risk factors associated with T. gondii infection in these pigs. The DNA samples from 17 sick pigs and seven stray cats, were successfully genotyped by multilocus PCR-restriction fragment length polymorphism (PCR-RFLP) with 10 genetic markers [SAG1, SAG2 (5'-3'SAG2, alt. SAG2), SAG3, GRA6, PK1, c22-8, c29-2, BTUB, L358 and Apico]. Six distinct genotypes were found, which were designated ToxoDB PCR-RFLP genotypes #9 (Chinese I), #10 (Type I), #213, and #89, and New 1 and New 2. Chinese I is the most prevalent T. gondii genotype in this region. The two new genotypes (designated New 1 and New 2) are reported and the ToxoDB PCR-RFLP genotype #89 is found for the first time in China. Such information will be useful for the prevention, diagnosis and treatment of porcine toxoplasmosis in Jiangsu Province, eastern China. Copyright © 2018 Elsevier B.V. All rights reserved.

Contribution of the polarization moments of different rank to the integral CPT signal

NASA Astrophysics Data System (ADS)

Taskova, E.; Alipieva, E.; Todorov, G.

2016-01-01

In the present work we investigate the relation of the polarization moments having different ranks with the tensor components which form the observable integral CPT signal, in the presence of a stray magnetic field. A numerical experiment with parameters close to the real ones is performed, using a program based on the irreducible tensor operator formalism1. The integral fluorescent signal is calculated for the non-polarized fluorescence at different laser power excitation. Detailed analysis of the numerical solutions for all tensor components which describe population and alignment allows visualizing the dynamics of their behavior in dependence on the experimental geometry and laboratory magnetic field B'. The dependence of population f00, longitudinal f02 and transverse f22 alignment in the presence of transverse magnetic field is investigated. The shape and sign of the resonance change with laser power.

Magnetic nanoparticle detection method employing non-linear magnetoimpedance effects

NASA Astrophysics Data System (ADS)

Beato-López, J. J.; Pérez-Landazábal, J. I.; Gómez-Polo, C.

2017-04-01

In this work, a sensitive tool to detect magnetic nanoparticles (Fe3O4) based on a non-linear Giant Magnetoimpedance (GMI) effect is presented. The GMI sensor is designed with four nearly zero magnetostrictive ribbons connected in series and was analysed as a function of a constant external magnetic field and exciting frequency. The influence of the magnetic nanoparticles deposited on the ribbon surface was characterized using the first (fundamental) and second (non-linear) harmonics of the magnetoinductive voltage. The results show a clear enhancement of the sensor response in the high magnetic field region (H = 1.5 kA/m) as a consequence of the stray field generated by the magnetic nanoparticles on the GMI ribbons' surface. The highest sensitivity ratios are obtained for the non-linear component in comparison with the fundamental response. The results open a new research strategy in magnetic nanoparticle detection.

Globally optimal superconducting magnets part II: symmetric MSE coil arrangement.

PubMed

Tieng, Quang M; Vegh, Viktor; Brereton, Ian M

2009-01-01

A globally optimal superconducting magnet coil design procedure based on the Minimum Stored Energy (MSE) current density map is outlined. The method has the ability to arrange coils in a manner that generates a strong and homogeneous axial magnetic field over a predefined region, and ensures the stray field external to the assembly and peak magnetic field at the wires are in acceptable ranges. The outlined strategy of allocating coils within a given domain suggests that coils should be placed around the perimeter of the domain with adjacent coils possessing alternating winding directions for optimum performance. The underlying current density maps from which the coils themselves are derived are unique, and optimized to possess minimal stored energy. Therefore, the method produces magnet designs with the lowest possible overall stored energy. Optimal coil layouts are provided for unshielded and shielded short bore symmetric superconducting magnets.

Perspectives of antiferromagnetic spintronics

NASA Astrophysics Data System (ADS)

Jungfleisch, Matthias B.; Zhang, Wei; Hoffmann, Axel

2018-04-01

Antiferromagnets are promising for future spintronic applications owing to their advantageous properties: They are magnetically ordered, but neighboring magnetic moments point in opposite directions, which results in zero net magnetization. This means antiferromagnets produce no stray fields and are insensitive to external magnetic field perturbations. Furthermore, they show intrinsic high frequency dynamics, exhibit considerable spin-orbit and magneto-transport effects. Over the past decade, it has been realized that antiferromagnets have more to offer than just being utilized as passive components in exchange bias applications. This development resulted in a paradigm shift, which opens the pathway to novel concepts using antiferromagnets for spin-based technologies and applications. This article gives a broad perspective on antiferromagnetic spintronics. In particular, the manipulation and detection of antiferromagnetic states by spintronics effects, as well as spin transport and dynamics in antiferromagnetic materials will be discussed. We will also outline current challenges and future research directions in this emerging field.

High-field penning-malmberg trap: confinement properties and use in positron accumulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartley, J.H.

1997-09-01

This dissertation reports on the development of the 60 kG cryogenic positron trap at Lawrence Livermore National Laboratory, and compares the trap`s confinement properties with other nonneutral plasma devices. The device is designed for the accumulation of up to 2{times}10{sup 9} positrons from a linear-accelerator source. This positron plasma could then be used in Bhabha scattering experiments. Initial efforts at time-of-flight accumulation of positrons from the accelerator show rapid ({approximately}100 ms) deconfinement, inconsistent with the long electron lifetimes. Several possible deconfinement mechanisms have been explored, including annihilation on residual gas, injection heating, rf noise from the accelerator, magnet field curvature,more » and stray fields. Detailed studies of electron confinement demonstrate that the empirical scaling law used to design the trap cannot be extrapolated into the parameter regime of this device. Several possible methods for overcoming these limitations are presented.« less

Perspectives of antiferromagnetic spintronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jungfleisch, Matthias B.; Zhang, Wei; Hoffmann, Axel

2018-04-01

Antiferromagnets are promising for future spintronics applications owing to their interesting properties: They are magnetically ordered, but neighboring magnetic moments point in opposite directions which results in zero net magneti- zation. This means antiferromagnets produce no stray fields and are insensitive to external magnetic field perturbations. Furthermore, they show intrinsic high frequency dynamics, exhibit considerable spin-orbit and magneto-transport effects. Over the past decade, it has been realized that antiferromagnets have more to offer than just being utilized as passive components in exchange bias applications. This development resulted in a paradigm shift, which opens the pathway to novel concepts using antiferromagnetsmore » for spin-based technologies and applications. This article gives a broad per- spective on antiferromagnetic spintronics. In particular, the manipulation and detection of anitferromagnetic states by spintronics effects, as well as spin transport and dynamics in antiferromagnetic materials will be discussed. We will also outline current challenges and future research directions in this emerging field.« less

VizieR Online Data Catalog: Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)

NASA Astrophysics Data System (ADS)

Kalberla, P. M. W.; Burton, W. B.; Hartmann, D.; Arnal, E. M.; Bajaja, E.; Morras, R.; Poeppel, W. G. L.

2005-07-01

The LAB survey contains the final data release of observations of 21-cm emission from Galactic neutral hydrogen over the entire sky, merging the Leiden/Dwingeloo Survey (LDS: Hartmann & Burton 1997, Cat. VIII/54) of the sky north of -30{deg} with the Instituto Argentino de Radioastronomia Survey (IAR: Arnal et al. 2000A&AS..142...35A and Bajaja et al. 2005, Cat. VIII/75) of the sky south of -25{deg}. The angular resolution of the combined material is HPBW ~ 0.6{deg}. The LSR velocity coverage spans the interval -450 km/s to +400 km/s, at a resolution of 1.3km/s. The data were corrected for stray radiation at the Institute for Radioastronomy of the University of Bonn, refining the original correction applied to the LDS. The rms brightness-temperature noise of the merged database is 0.07-0.09 K. Residual errors in the profile wings due to defects in the correction for stray radiation are for most of the data below a level of 20-40 mK. It would be necessary to construct a telescope with a main beam efficiency of {eta}MB>99% to achieve the same accuracy. The merged and refined material entering the LAB Survey of Galactic H I is intended to be a general resource useful to a wide range of studies of the physical and structural characteristices of the Galactic interstellar environment. The LAB Survey is the most sensitive Milky Way H I survey to date, with the most extensive coverage both spatially and kinematically. The Survey is available as 3-D maps, with or without Hanning smoothing, covering the whole +/-458km/s or limited to +/-250km/s range. The resolution of the 3-D maps is 0.5{deg} in galactic longitude and latitude, and up to 1km/s in velocity. The survey exists also as (b,v) maps at longitude intervals stepped by 0.5{deg} -- these files supersedes the FITS files given in the Hartmann and Burton Atlas (Cat. VIII/54) (1 data file).

Field-cycling NMR experiments in an ultra-wide magnetic field range: relaxation and coherent polarization transfer.

PubMed

Zhukov, Ivan V; Kiryutin, Alexey S; Yurkovskaya, Alexandra V; Grishin, Yuri A; Vieth, Hans-Martin; Ivanov, Konstantin L

2018-05-09

An experimental method is described allowing fast field-cycling Nuclear Magnetic Resonance (NMR) experiments over a wide range of magnetic fields from 5 nT to 10 T. The method makes use of a hybrid technique: the high field range is covered by positioning the sample in the inhomogeneous stray field of the NMR spectrometer magnet. For fields below 2 mT a magnetic shield is mounted on top of the spectrometer; inside the shield the magnetic field is controlled by a specially designed coil system. This combination allows us to measure T1-relaxation times and nuclear Overhauser effect parameters over the full range in a routine way. For coupled proton-carbon spin systems relaxation with a common T1 is found at low fields, where the spins are "strongly coupled". In some cases, experiments at ultralow fields provide access to heteronuclear long-lived spin states. Efficient coherent polarization transfer is seen for proton-carbon spin systems at ultralow fields as follows from the observation of quantum oscillations in the polarization evolution. Applications to analysis and the manipulation of heteronuclear spin systems are discussed.

On the matter of building high-frequency amplifiers minimally influenced by interstage stray reactances

NASA Astrophysics Data System (ADS)

A, Volkov Y.

2017-01-01

The expedience of building wideband multistage amplifiers, the stages of which are connected with each other so, that the “modes of impedance mismatch” are realized, is justified. Those modes allow us to reduce considerably the sensitivity of amplifier transfer factors to the stray (constructional) capacitances and inductances of interstage circuits. The procedure of synthesizing the schematics of such amplifiers is proposed, the efficiency and clarity of which are provided by using the method of signal graphs.

Suppression of shunting current in a magnetically insulated coaxial vacuum diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yalandin, M. I.; Sharypov, K. A.; Shpak, V. G.

2015-06-08

Real-time investigations of the dynamics of explosive electron emission from a high-voltage cathode holder made of nonmagnetic stainless steel in a magnetically insulated coaxial vacuum diode have been performed. It has been shown that aging the cathode with several tens of voltage pulses at a field of 1–2 MV/cm provides a stray emission delay ranging from hundreds of picoseconds to a nanosecond or more. In addition, the magnetic field must be configured so that the magnetic lines would not cross the vacuum gap between the diode case and the cathode holder in the region behind the emitting edge of themore » cathode. These efforts provide conditions for stable emission of the working beam from a graphite cathode with a sharp emitting edge.« less

Spurious Grain Formation at Cross-Sectional Expansion During Directional Solidification: Influence of Thermosolutal Convection

NASA Astrophysics Data System (ADS)

Ghods, M.; Lauer, M.; Upadhyay, S. R.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

2018-04-01

Formation of spurious grains during directional solidification (DS) of Al-7 wt.% Si and Al-19 wt.% Cu alloys through an abrupt increase in cross-sectional area has been examined by experiments and by numerical simulations. Stray grains were observed in the Al-19 wt.% Cu samples and almost none in the Al-7 wt.% Si. The locations of the stray grains correlate well where numerical solutions indicate the solute-rich melt to be flowing up the thermal gradient faster than the isotherm velocity. It is proposed that the spurious grain formation occurred by fragmentation of slender tertiary dendrite arms was enhanced by thermosolutal convection. In Al-7 wt.% Si, the dendrite fragments sink in the surrounding melt and get trapped in the dendritic array growing around them, and therefore they do not grow further. In the Al-19 wt.% Cu alloy, on the other hand, the dendrite fragments float in the surrounding melt and some find conducive thermal conditions for further growth and become stray grains.

Carbon Nanotubes on Titanium Substrates for Stray Light Suppression

NASA Technical Reports Server (NTRS)

Hagopian, John; Getty, Stephanie; Quijada, Manuel

2011-01-01

A method has been developed for growing carbon nanotubes on a titanium substrate, which makes the nano tubes ten times blacker than the current state-of-the-art paints in the visible to near infrared. This will allow for significant improvement of stray light performance in scientific instruments, or any other optical system. Because baffles, stops, and tubes used in scientific observations often undergo loads such as vibration, it is critical to develop this surface treatment on structural materials. This innovation optimizes the carbon nano - tube growth for titanium, which is a strong, lightweight structural material suitable for spaceflight use. The steps required to grow the nanotubes require the preparation of the surface by lapping, and the deposition of an iron catalyst over an alumina stiction layer by e-beam evaporation. In operation, the stray light controls are fabricated, and nanotubes (multi-walled 100 microns in length) are grown on the surface. They are then installed in the instruments or other optical devices.

Bidirectional reflectance distribution function /BRDF/ measurements of stray light suppression coatings for the Space Telescope /ST/

NASA Technical Reports Server (NTRS)

Griner, D. B.

1979-01-01

The paper considers the bidirectional reflectance distribution function (BRDF) of black coatings used on stray light suppression systems for the Space Telescope (ST). The ST stray light suppression requirement is to reduce earth, moon, and sun light in the focal plane to a level equivalent to one 23 Mv star per square arcsecond, an attenuation of 14 orders of magnitude. It is impractical to verify the performance of a proposed baffle system design by full scale tests because of the large size of the ST, so that a computer analysis is used to select the design. Accurate computer analysis requires a knowledge of the diffuse scatter at all angles from the surface of the coatings, for all angles of incident light. During the early phases of the ST program a BRDF scanner was built at the Marshall Space Flight Center to study the scatter from black materials; the measurement system is described and the results of measurements on samples proposed for use on the ST are presented.

Genetic evidence of enzootic leishmaniasis in a stray canine and Texas mouse from sites in west and central Texas

PubMed Central

Kipp, Evan J; Mariscal, Jacqueline; Armijos, Rodrigo X; Weigel, Margaret; Waldrup, Kenneth

2016-01-01

We detected Leishmania mexicana in skin biopsies taken from a stray canine (Canis familiaris) and Texas mouse (Peromyscus attwateri) at two ecologically disparate sites in west and central Texas using polymerase chain reaction (PCR). A single PCR-positive dog was identified from a sample of 96 stray canines and was collected in a peri-urban area in El Paso County, Texas. The PCR-positive P. attwateri was trapped at a wildlife reserve in Mason County, Texas, from a convenience sample of 20 sylvatic mammals of different species. To our knowledge, this represents the first description of L. mexicana in west Texas and extends the known geographic range of the parasite to an area that includes the arid Chihuahuan Desert. Our finding of L. mexicana in P. attwateri represents a new host record and is the first description of the parasite in a wild peromyscid rodent in the United States. PMID:27759765

Life on magnets: stem cell networking on micro-magnet arrays.

PubMed

Zablotskii, Vitalii; Dejneka, Alexandr; Kubinová, Šárka; Le-Roy, Damien; Dumas-Bouchiat, Frédéric; Givord, Dominique; Dempsey, Nora M; Syková, Eva

2013-01-01

Interactions between a micro-magnet array and living cells may guide the establishment of cell networks due to the cellular response to a magnetic field. To manipulate mesenchymal stem cells free of magnetic nanoparticles by a high magnetic field gradient, we used high quality micro-patterned NdFeB films around which the stray field's value and direction drastically change across the cell body. Such micro-magnet arrays coated with parylene produce high magnetic field gradients that affect the cells in two main ways: i) causing cell migration and adherence to a covered magnetic surface and ii) elongating the cells in the directions parallel to the edges of the micro-magnet. To explain these effects, three putative mechanisms that incorporate both physical and biological factors influencing the cells are suggested. It is shown that the static high magnetic field gradient generated by the micro-magnet arrays are capable of assisting cell migration to those areas with the strongest magnetic field gradient, thereby allowing the build up of tunable interconnected stem cell networks, which is an elegant route for tissue engineering and regenerative medicine.

Processing of DMSP magnetic data: Handbook of programs, tapes, and datasets

NASA Technical Reports Server (NTRS)

Langel, R. A.; Sabaka, T. J.; Ridgway, J. R.

1990-01-01

The DMSP F-7 satellite was an operational Air Force meteorological satellite which carried a magnetometer for geophysical measurements. The magnetometer was located within the body of the spacecraft in the presence of large spacecraft fields. In addition to stray magnetic fields, the data have inherent position and time inaccuracies. Algorithms were developed to identify and remove time varying magnetic field noise from the data. These algorithms are embodied in an automated procedure which fits a smooth curve through the data and then identifies outliers and which filters the predominant Fourier component of noise from the data. Techniques developed for Magsat were then modified and used to attempt determination of the spacecraft fields, of any rotation between the magnetometer axes and the spacecraft axes, and of any scale changes within the magnetometer itself. Software setup and usage are documented and program listings are included in the Appendix. The initial and resulting data are archived on magnetic cartridge and the formats are documented.

Electromagnetic properties of a modular MHD thruster

NASA Astrophysics Data System (ADS)

Kom, C. H.; Brunet, Y.

1999-04-01

The magnetic field of an annular MHD thruster made of independent superconducting modules has been studied with analytical and numerical methods. This configuration allows to obtain large magnetized volumes and high induction levels with rapidly decreasing stray fields. When some inductors are out of order, the thruster remains still operational, but the stray fields increase in the vicinity of the failure. For given structural materials and superconductors, it is possible to determine the size of the conductor in order to reduce the electromagnetic forces and the peak field supported by the conductors. For an active field of 10 T in a 6 m ray annular active channel of a thruster with 24 modules, the peak field is exactly 15.6 T in the Nb3Sn conductors and the structure has to sustain 10^8 N/m forces. The necessity to place some magnetic or superconducting shield is discussed, particularly when the thruster is in a degraded regime. Nous présentons une étude analytique et numérique du champ magnétique d'un propulseur MHD naval annulaire, constitué de secteurs inducteurs supraconducteurs. Cette configuration nécessite des champs magnétiques élevés dans des volumes importants, et permet une décroissance rapide des champs de fuite. Lorsque quelques inducteurs sont en panne, le propulseur reste toujours opérationnel, mais les champs de fuite sont importants aux environs des modules hors service. Étant donné un matériau supraconducteur, il est possible de déterminer la forme des inducteurs dans le but de réduire à la fois les forces électromagnétiques et le surchamp supporté par le bobinage. Pour un propulseur annulaire constitué de 24 modules inducteurs, et un champ actif de 10 T au centre de la partie active du canal (r = 6 m) on obtient avec du Nb3Sn un champ maximun sur le conducteur de 15,5 T et la structure supporte une force de 10^8 N/m. De plus, la nécessité de placer des écrans magnétique ou supraconducteur en régime dégradé (mise hors service d'un ou de plusieurs modules inducteurs) est discutée.

AsteroidFinder - the space-borne telescope to search for NEO Asteroids

NASA Astrophysics Data System (ADS)

Hartl, M.; Mosebach, H.; Schubert, J.; Michaelis, H.; Mottola, S.; Kührt, E.; Schindler, K.

2017-11-01

This paper presents the mission profile as well as the optical configuration of the space-borne AsteroidFinder telescope. Its main objective is to retrieve asteroids with orbits interior to the earth's orbit. The instrument requires high sensitivity to detect asteroids with a limiting magnitude of equal or larger than 18.5mag (V-Band) and astrometric accuracy of 1arcsec (1σ). This requires a telescope aperture greater than 400cm2, high image stability, detector with high quantum efficiency (peak > 90%) and very low noise, which is only limited by zodiacal background. The telescope will observe the sky between 30° and 60° in solar elongation. The telescope optics is based on a Cook type TMA. An effective 2°×2° field of view (FOV) is achieved by a fast F/3.4 telescope with near diffraction-limited performance. The absence of centre obscuration or spiders in combination with an accessible intermediate field plane and exit pupil allow for efficient stray light mitigation. Design drivers for the telescope are the required point spread function (PSF) values, an extremely efficient stray light suppression (due to the magnitude requirement mentioned above), the detector performance, and the overall optical and mechanical stability for all orientations of the satellite. To accommodate the passive thermal stabilization scheme and the necessary structural stability, the materials selection for the telescope main structure and the mirrors are of vital importance. A focal plane with four EMCCD detectors is envisaged. The EMCCD technology features shorter integration times, which is in favor regarding the pointing performance of the satellite. The launch of the mission is foreseen for the year 2013 with a subsequent mission lifetime of at least 1 year.

A display model for the TOU of PLATO: just a cool toy or a benchmark of opportunities?

NASA Astrophysics Data System (ADS)

Dima, M.; Greggio, D.; Bergomi, M.; Biondi, F.; Farinato, J.; Farisato, G.; Magrin, D.; Lessio, L.; Marafatto, L.; Munari, M.; Pagano, I.; Ragazzoni, R.; Viotto, V.; Piazza, D.

2016-07-01

We produced a "toy-model" of one Telescope Optical Unit of PLATO, the Medium sized mission selected by ESA to fly in 2024. This is a six lenses dioptric very wide field camera with a window in front to take care of radiation impact on the first lens whose optical glass cannot be replaced with a radiation hardened one. The main aim of this project is just to produce a "cool" model for display purposes, in which one can "explore" the details of the inside through some openings in the tube, in order to visually inspect some of the fine details of the opto-mechanics. While its didactic and advertising role is out of doubt, during its construction we realized that some interesting outcome can be of some relevance for the project itself and that some findings could be useful, in order to assess the ability of producing with the same technology some (of course of much more modest quality) optical systems. In this context, we immediately dropped the option of producing the lenses with opaque material painted with a color resembling a refractive material (like blue for instance) and decided to actually produce them with transparent plastic. Furthermore the surfaces are then finely polished in order to give them basic optical properties. Such an optical system has only very coarsely the converging properties of the original nominal design for a number of reasons: the refractive indexes are not the nominal ones, the quality of the surfaces and their nominal values are only roughly, within a few percent, the targeted one, and the way the surfaces are built up makes them prone to some diffraction effects. However, the bulk of the lens and the surface roughness will give a large magnification of the scattering effects that will be experienced, at a much lower level, on the actual flight model. We investigated through propagation of a laser beam and by digital camera the main stray light modes that this toymodel offers. In other words, the model amplifies, to a large extent, the negative bulk scattering and spurious reflection just because surfaces and materials are orders of magnitude rougher that the intended ones. Even if this did not allow to attempt to make any quantitative measurement, in order to scale down to the actual one, we used it to look out independently for the main sources of stray light and we compared them with the one discussed by the optical design team, obtained using professional ray tracing code. Finally, we point out some of the technicalities used in the design to mimic the finest mechanical elements that cannot be safely incorporate in the final design and to produce pieces of size much larger than the maximum volume allowed by our 3D printer in a single shot.

New main reflector, subreflector and dual chamber concepts for compact range applications

NASA Technical Reports Server (NTRS)

Pistorius, C. W. I.; Burnside, W. D.

1987-01-01

A compact range is a facility used for the measurement of antenna radiation and target scattering problems. Most presently available parabolic reflectors do not produce ideal uniform plane waves in the target zone. Design improvements are suggested to reduce the amplitude taper, ripple and cross polarization errors. The ripple caused by diffractions from the reflector edges can be reduced by adding blended rolled edges and shaping the edge contour. Since the reflected edge continues smoothly from the parabola onto the rolled surface, rather than being abruptly terminated, the discontinuity in the reflected field is reduced which results in weaker diffracted fields. This is done by blending the rolled edges from the parabola into an ellipse. An algorithm which enables one to design optimum blended rolled edges was developed that is based on an analysis of the continuity of the surface radius of curvature and its derivatives across the junction. Futhermore, a concave edge contour results in a divergent diffracted ray pattern and hence less stray energy in the target zone. Design equations for three-dimensional reflectors are given. Various examples were analyzed using a new physical optics method which eliminates the effects of the false scattering centers on the incident shadow boundaries. A Gregorian subreflector system, in which both the subreflector and feed axes are tilted, results in a substantial reduction in the amplitude taper and cross polarization errors. A dual chamber configuration is proposed to eliminate the effects of diffraction from the subreflector and spillover from the feed. A computationally efficient technique, based on ray tracing and aperture integration, was developed to analyze the scattering from a lossy dielectric slab with a wedge termination.

A PARASITOLOGIC AND MOLECULAR SURVEY OF HEPATOZOON CANIS INFECTION IN STRAY DOGS IN NORTHEAST OF IRAN.

PubMed

Barati, Ali; Razmi, Gholamreza

2018-05-15

Canine hepatozoonosis, caused by H. canis, is a tick-borne disease in domestic and wild dogs that is transmitted by ingestion of Rhipicephalus sanguineus ticks. The aim of the study was to detect H. canis in stray dogs in Iran using blood smear examination and molecular techniques. From October 2014 to September 2015, 150 EDTA blood samples were collected from stray dogs in the northeast region of Iran. Blood smears were microscopically examined for the presence of Hepatozoon gamonts; whole blood was evaluated by PCR, with subsequent sequencing and phylogenetic analysis. Hepatozoon spp. Gamonts were observed in the neutrophils of 5/150 (3.3%) blood smears, whereas Hepatozoon spp. 18S rDNA was detected in 12/150 (8.0%) blood samples from stray dogs. There was a good agreement between microscopy and PCR methods. (Kappa= 0.756). The highest rate of infection was seasonally detected in the summer (p<0.05). The difference of frequency of Hepatozoon spp infection was not significant by gender and age factors (p>0.05). The alignment analysis of the sequenced samples showed ≥99% similarity with other nucleotide sequences of Hepatozoon spp. in GenBank. The phylogenetic tree also revealed that the nucleotide sequences in this study were clustered in the H. canis clade and different from the H. felis and H. americanum clades. According to the results, it is concluded that H. canis infection is present among dogs in northeastern region of Iran.

Toxocara nematodes in stray cats from shiraz, southern iran: intensity of infection and molecular identification of the isolates.

PubMed

Mikaeili, Fattaneh; Mirhendi, Hossein; Hosseini, Mostafa; Asgari, Qasem; Kia, Eshrat Beigom

2013-10-01

Toxocara is a common nematode of cats in different parts of Iran. Despite the close association of cats with human, no attempt has been done so far for molecular identification of this nematode in the country. Therefore, current study was performed on identification of some isolates of Toxocara from stray cats in Shiraz, Fars Province, Southern Iran, based on morphological and molecular approaches, and also determination of intensity of infection. This cross-sectional study was carried out on 30 stray cats trapped from different geographical areas of Shiraz in 2011. Adult male and female worms were recovered from digestive tract after dissection of cats. Morphological features using existing keys and PCR-sequencing of ITS-rDNA region and pcox1 mitochondrial l gene were applied for the delineating the species of the parasites. Eight out of 30 cats (26.7%) were found infected with Toxocara nematodes. All the isolates were confirmed as Toxocara cati based on morphological features and the sequence of ribosomal and mitochondrial targets. Intensity of infection ranged from one to a maximum of 39 worms per cat, with a mean of 10.25±12.36, and higher abundance of female nematodes. The most prevalent ascaridoid nematode of stray cats in the study area was T. cati and female nematodes were more abundant than that of males. This issue has important role in spreading of eggs in the environment and impact on human toxocariasis.

Absence of acute ocular damage in humans after prolonged exposure to intense RF EMF

NASA Astrophysics Data System (ADS)

Adibzadeh, F.; van Rhoon, G. C.; Verduijn, G. M.; Naus-Postema, N. C.; Paulides, M. M.

2016-01-01

The eye is considered to be a critical organ when determining safety standards for radio frequency (RF) radiation. Experimental data obtained using animals showed that RF heating of the eye, particularly over a specific threshold, can induce cataracts. During the treatment of cancer in the head and neck by hyperthermia, the eyes receive a considerable dose of RF radiation due to stray radiation from the prolonged (60 min) and intense exposure at 434 MHz of this region. In the current study, we verified the exposure guidelines for humans by determining the association between the electromagnetic and thermal dose in the eyes with the reported ocular effects. We performed a simulation study to retrospectively assess the specific absorption rate (SAR) and temperature increase in the eyes of 16 selected patients (encompassing a total of 74 treatment sessions) whose treatment involved high power delivery as well as a minimal distance between the tumor site and the eye. Our results show that the basic restrictions on the peak 10 g spatial-averaged SAR (10 W kg-1) and peak tissue temperature increase (1 °C) are exceeded by up to 10.4 and 4.6 times, on average, and by at least 6.2 and 1.8 times when considering the lower limit of the 95% confidence interval. Evaluation of the acute effects according to patients’ feedback (all patients), the common toxicity criteria scores (all patients) and an ophthalmology investigation (one patient with the highest exposure) revealed no indication of any serious acute ocular effect, even though the eyes were exposed to high electromagnetic fields, leading to a high thermal dose. We also found that, although there is a strong correlation (R 2  =  0.88) between the predicted induced SAR and temperature in the eye, there are large uncertainties regarding the temperature-SAR relationship. Given this large uncertainty (129%) compared with the uncertainty of 3D temperature simulations (61%), we recommend using temperature simulations as a dosimetric measure in electromagnetic exposure risk assessments.

Landsat-8 TIRS thermal radiometric calibration status

USGS Publications Warehouse

Barsi, Julia A.; Markham, Brian L.; Montanaro, Matthew; Gerace, Aaron; Hook, Simon; Schott, John R.; Raqueno, Nina G.; Morfitt, Ron

2017-01-01

The Thermal Infrared Sensor (TIRS) instrument is the thermal-band imager on the Landsat-8 platform. The initial onorbit calibration estimates of the two TIRS spectral bands indicated large average radiometric calibration errors, -0.29 and -0.51 W/m2 sr μm or -2.1K and -4.4K at 300K in Bands 10 and 11, respectively, as well as high variability in the errors, 0.87K and 1.67K (1-σ), respectively. The average error was corrected in operational processing in January 2014, though, this adjustment did not improve the variability. The source of the variability was determined to be stray light from far outside the field of view of the telescope. An algorithm for modeling the stray light effect was developed and implemented in the Landsat-8 processing system in February 2017. The new process has improved the overall calibration of the two TIRS bands, reducing the residual variability in the calibration from 0.87K to 0.51K at 300K for Band 10 and from 1.67K to 0.84K at 300K for Band 11. There are residual average lifetime bias errors in each band: 0.04 W/m2 sr μm (0.30K) and -0.04 W/m2 sr μm (-0.29K), for Bands 10 and 11, respectively.

Thomson scattering diagnostic on the Compact Toroidal Hybrid Experiment

NASA Astrophysics Data System (ADS)

Traverso, P. J.; Ennis, D. A.; Hartwell, G. J.; Kring, J. D.; Maurer, D. A.

2017-10-01

A Thomson scattering system is being commissioned for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH), a five-field period current-carrying torsatron. The system takes a single point measurement at the magnetic axis to both calibrate the two-color soft x-ray Te system and serve as an additional diagnostic for the V3FIT 3D equilibrium reconstruction code. A single point measurement will reduce the uncertainty in the reconstructed peak pressure by an order of magnitude for both current-carrying plasmas and future gyrotron-heated stellarator plasmas. The beam, generated by a frequency doubled Continuum 2 J, Nd:YAG laser, is passed vertically through an entrance Brewster window and a two-aperture optical baffle system to minimize stray light. Thomson scattered light is collected by two adjacent f/2 plano-convex condenser lenses and routed via a fiber bundle through a Holospec f/1.8 spectrograph. The red-shifted scattered light from 533-563 nm will be collected by an array of Hamamatsu H11706-40 PMTs. The system has been designed to measure plasmas with core Te of 100 to 200 eV and densities of 5 ×1018 to 5 ×1019 m-3. Stray light and calibration data for a single wavelength channel will be presented. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

Iron-platinum-coated carbon nanocone probes on tipless cantilevers for high resolution magnetic force imaging.

PubMed

Chen, I-Chen; Chen, Li-Han; Gapin, Andrew; Jin, Sungho; Yuan, Lu; Liou, Sy-Hwang

2008-02-20

High coercivity iron-platinum-coated carbon nanocones (CNCs) have been fabricated for magnetic force microscopy (MFM) by direct-current plasma-enhanced chemical vapor deposition growth of nanocones on tipless cantilevers followed by sputtering and annealing of the FePt film. The FePt-coated CNC probe has many localized magnetic stray fields due to the high-aspect-ratio geometry and small radius of the tip. The MFM imaging on magnetic recording media was performed using CNC probes and compared with the imaging by FePt-coated silicon probes. An image with 20 nm lateral resolution has been demonstrated.

Domain-wall superconductivity in superconductor-ferromagnet hybrids.

PubMed

Yang, Zhaorong; Lange, Martin; Volodin, Alexander; Szymczak, Ritta; Moshchalkov, Victor V

2004-11-01

Superconductivity and magnetism are two antagonistic cooperative phenomena, and the intriguing problem of their coexistence has been studied for several decades. Recently, artificial hybrid superconductor-ferromagnet systems have been commonly used as model systems to reveal the interplay between competing superconducting and magnetic order parameters, and to verify the existence of new physical phenomena, including the predicted domain-wall superconductivity (DWS). Here we report the experimental observation of DWS in superconductor-ferromagnet hybrids using a niobium film on a BaFe(12)O(19) single crystal. We found that the critical temperature T(c) of the superconductivity nucleation in niobium increases with increasing field until it reaches the saturation field of BaFe(12)O(19). In accordance with the field-shift of the maximum value of T(c), pronounced hysteresis effects have been found in resistive transitions. We argue that the compensation of the applied field by the stray fields of the magnetic domains as well as the change in the domain structure is responsible for the appearance of the DWS and the coexistence of superconductivity and magnetism in the superconductor-ferromagnet hybrids.

Test-particle simulations of SEP propagation in IMF with large-scale fluctuations

NASA Astrophysics Data System (ADS)

Kelly, J.; Dalla, S.; Laitinen, T.

2012-11-01

The results of full-orbit test-particle simulations of SEPs propagating through an IMF which exhibits large-scale fluctuations are presented. A variety of propagation conditions are simulated - scatter-free, and scattering with mean free path, λ, of 0.3 and 2.0 AU - and the cross-field transport of SEPs is investigated. When calculating cross-field displacements the Parker spiral geometry is accounted for and the role of magnetic field expansion is taken into account. It is found that transport across the magnetic field is enhanced in the λ =0.3 AU and λ =2 AU cases, compared to the scatter-free case, with the λ =2 AU case in particular containing outlying particles that had strayed a large distance across the IMF. Outliers are catergorized by means of Chauvenet's criterion and it is found that typically between 1 and 2% of the population falls within this category. The ratio of latitudinal to longitudinal diffusion coefficient perpendicular to the magnetic field is typically 0.2, suggesting that transport in latitude is less efficient.

Life on Magnets: Stem Cell Networking on Micro-Magnet Arrays

PubMed Central

Zablotskii, Vitalii; Dejneka, Alexandr; Kubinová, Šárka; Le-Roy, Damien; Dumas-Bouchiat, Frédéric; Givord, Dominique; Dempsey, Nora M.; Syková, Eva

2013-01-01

Interactions between a micro-magnet array and living cells may guide the establishment of cell networks due to the cellular response to a magnetic field. To manipulate mesenchymal stem cells free of magnetic nanoparticles by a high magnetic field gradient, we used high quality micro-patterned NdFeB films around which the stray field’s value and direction drastically change across the cell body. Such micro-magnet arrays coated with parylene produce high magnetic field gradients that affect the cells in two main ways: i) causing cell migration and adherence to a covered magnetic surface and ii) elongating the cells in the directions parallel to the edges of the micro-magnet. To explain these effects, three putative mechanisms that incorporate both physical and biological factors influencing the cells are suggested. It is shown that the static high magnetic field gradient generated by the micro-magnet arrays are capable of assisting cell migration to those areas with the strongest magnetic field gradient, thereby allowing the build up of tunable interconnected stem cell networks, which is an elegant route for tissue engineering and regenerative medicine. PMID:23936425

Equivalent circuit simulation of cylindrical monopole impedance measurements in ionospheric electron plasma

NASA Astrophysics Data System (ADS)

Kiraga, A.

Several common problems occur in measurement techniques and interpretation of plasma natural emissions and impedance data. Antenna characteristics are of prime importance in equivalent circuit analysis. Spacecraft - plasma interaction contributes to variability of equivalent circuit impedances and e.m.f. components and imposes constrains on usefulness of experimental data. In order to have independent, built in estimate of local plasma frequency and to get deeper insight into properties of equivalent circuit for wave diagnostics, impedance measurement was integrated with radio receivers on the ACTIVE, APEX and CORONAS satellites. Impedance measurements of 7.5m long monopole were performed in frequency range .1-10MHz with the frequency step of 50kHz, in voltage divider configuration. Due to high inclination of 82.5deg and altitude range of 500-3000km, data from very different plasmas were collected. Data can be split into quasi normal, disturbed and very disturbed measurements. Equivalent circuit structure evolved in attempt to m tcha even very disturbed measurements. For quasi normal measurements, satisfactory matching is obtained with computed gyrofrequency fc and fitted plasma frequency fn, stray capacitance Cs and capacitance Cv of phenomenological vacuum sheath. With Balmain formula for monopole impedance in cold magnetoplasma, two basic spectral structures are explained. For sufficiently magnetized plasma (roughly fn/fc<2 if Cs=20pF), circuit parallel resonance frequency Fr falls into upper hybrid band (max(fn,fc),fu), resonance amplitude is reduced by high antenna resistance and horn like absolute maximum points fu. For values of fn/fc ratio, greater then critical, Fr is less than fn and broad absolute maximum at Fr follows from low antenna resistance. Further increase of fn/fc results in increasing lag of Fr behind fn. Critical rati o fn/fc increases with decreasing stray capacitance Cs. It follows from data analysis that stray capacitance may change in flight, at least due to attitude changes, so mentioned basic structures may be relevant in stray compensated bridge configuration. It is found that strongly disturbed measurements are related to activation of fast diodes, designed for input protection. Injections of charged particle beams saturated instrument. On line telemetry transmission interfered directly by receipted VHF fields and indirectly by particle acceleration leading to differential charging and direct current flow. In dense equatorial plasma, very peculiar evolution of base voltage spectra is linked to differential charging and intense direct current flow of thermal electrons. Deep, quasi periodic modulations or irregular excursions on time scales much shorter than sweep period are indicative of differential charging by ambient, energetic minor populations. Presented data and simulations address challenges in instrument design, monitoring and onboard data processing.

Phase diagrams of vortex matter with multi-scale inter-vortex interactions in layered superconductors.

PubMed

Meng, Qingyou; Varney, Christopher N; Fangohr, Hans; Babaev, Egor

2017-01-25

It was recently proposed to use the stray magnetic fields of superconducting vortex lattices to trap ultracold atoms for building quantum emulators. This calls for new methods for engineering and manipulating of the vortex states. One of the possible routes utilizes type-1.5 superconducting layered systems with multi-scale inter-vortex interactions. In order to explore the possible vortex states that can be engineered, we present two phase diagrams of phenomenological vortex matter models with multi-scale inter-vortex interactions featuring several attractive and repulsive length scales. The phase diagrams exhibit a plethora of phases, including conventional 2D lattice phases, five stripe phases, dimer, trimer, and tetramer phases, void phases, and stable low-temperature disordered phases. The transitions between these states can be controlled by the value of an applied external field.

Epidemiological role of dogs since the human leishmaniosis outbreak in Madrid.

PubMed

Miró, Guadalupe; Müller, Aurora; Montoya, Ana; Checa, Rocía; Marino, Valentina; Marino, Eloy; Fuster, Fernando; Escacena, Cristina; Descalzo, Miguel Angel; Gálvez, Rosa

2017-04-26

Canine leishmaniosis (CanL) has been in the spotlight since the 2009 outbreak of human leishmaniosis in Madrid. In the framework of the Leishmaniosis Surveillance Programme set up in Madrid, this study examines Leishmania-specific seroprevalences in stray dogs for the outbreak area and rest of the Madrid region over the period spanning from the outbreak to the present (2009-2016). These data are of interest because stray dogs could be sentinels for disease surveillance in endemic areas. Since 2011, we have also been monitoring owned dogs in the outbreak area. Over the study period, Leishmania infantum seroprevalence was determined in 2,123 stray dogs from the outbreak and non-outbreak areas. A serological study was also performed for owned dogs in the outbreak area: high-risk dogs such as hunting or farm dogs (n = 1,722) and pets (n = 1372). All dogs were examined and blood was collected. The variables recorded for each animal were: breed, age, sex, and clinical history indicating if the animal was healthy or clinically suspected of having any disease, and if they showed a clinical picture compatible with CanL. Seroprevalences of L. infantum in stray dogs were similar in the two areas examined: 4.7% (20 out of 346) in the outbreak area and 5.4% (96 out of 1,777) in the remaining Madrid region (χ 2  = 0.080, P = 0.777). A significant association was found between seroprevalence and age (z = -6.319; P < 0.001). Seroprevalence in owned dogs in the outbreak area was 2.1% in high-risk dogs (37 out of 1,722) and 1.2% in pets (17 out of 1,372) (χ 2  = 3.561, P = 0.0591). Both stray and owned dogs do not seem to play an important role in maintaining the transmission cycle of L. infantum in the Madrid outbreak area. The stable seroprevalence of infection observed in sentinel dogs suggests the good clinical management and prevention of CanL by local practitioners in owned dogs.

Fast space-varying convolution using matrix source coding with applications to camera stray light reduction.

PubMed

Wei, Jianing; Bouman, Charles A; Allebach, Jan P

2014-05-01

Many imaging applications require the implementation of space-varying convolution for accurate restoration and reconstruction of images. Here, we use the term space-varying convolution to refer to linear operators whose impulse response has slow spatial variation. In addition, these space-varying convolution operators are often dense, so direct implementation of the convolution operator is typically computationally impractical. One such example is the problem of stray light reduction in digital cameras, which requires the implementation of a dense space-varying deconvolution operator. However, other inverse problems, such as iterative tomographic reconstruction, can also depend on the implementation of dense space-varying convolution. While space-invariant convolution can be efficiently implemented with the fast Fourier transform, this approach does not work for space-varying operators. So direct convolution is often the only option for implementing space-varying convolution. In this paper, we develop a general approach to the efficient implementation of space-varying convolution, and demonstrate its use in the application of stray light reduction. Our approach, which we call matrix source coding, is based on lossy source coding of the dense space-varying convolution matrix. Importantly, by coding the transformation matrix, we not only reduce the memory required to store it; we also dramatically reduce the computation required to implement matrix-vector products. Our algorithm is able to reduce computation by approximately factoring the dense space-varying convolution operator into a product of sparse transforms. Experimental results show that our method can dramatically reduce the computation required for stray light reduction while maintaining high accuracy.

Zoonotic Intestinal Trematodes in Stray Cats (Felis catus) from Riverside Areas of the Republic of Korea

PubMed Central

Shin, Sung-Shik; Oh, Dae-Sung; Ahn, Kyu-Sung; Cho, Shin-Hyeong; Lee, Won-Ja; Na, Byoung-Kuk; Sohn, Woon-Mok

2015-01-01

The present study was performed to survey the infection status of zoonotic intestinal trematode (ZIT) in stray cats from 5 major riverside areas in the Republic of Korea. Total 400 stray cats were captured with live-traps in riverside areas of Seomjingang (‘gang’ means river) (203 cats) from June to October 2010, and of Yeongsangang (41), Nakdonggang (57), Geumgang (38), and Hangang (61 cats) from June to October 2011, respectively. Small intestines resected from cats were opened with a pair of scissors in a beaker with 0.85% saline and examined with naked eyes and under a stereomicroscope. More than 16 ZIT species were detected in 188 (92.6%) cats from Seomjingang areas, and the number of worms recovered was 111 per cat infected. In cats from riverside areas of Yeongsangang, Nakdonggang, Geumgang, and Hangang, more than 9, 8, 3, and 5 ZIT species were recovered, and the worm burdens were 13, 42, 11, and 56 specimens per infected cat, respectively. As the members of family Heterophyidae, more than 10 species, i.e., Metagonimus spp., Pygidiopsis summa, Heterophyes nocens, Stellantchasmus falcatus, Heterophyopsis continua, Acanthotrema felis, Centrocestus armatus, Procerovum varium, Cryptocotyle concava, and Stictodora lari, were recovered. More than 5 species of echinostomes, i.e., Echinostoma hortense, Echinochasmus japonicus, Echinochasmus sp., Echinoparyphium sp., and unidentified larval echinostomes, were collected. Plagiorchis spp. were detected in cats from areas of Seomjin-gang and Yeongsangang. From the above results, it has been confirmed that stray cats in 5 major riverside areas of Korea are highly infected with various species of ZITs. PMID:25925180

Vector-Borne Pathogens in Stray Dogs in Northeastern Turkey.

PubMed

Guven, Esin; Avcioglu, Hamza; Cengiz, Seyda; Hayirli, Armagan

2017-08-01

This experiment was carried out to attain prevalence and molecular characterization of pathogens causing canine vector-borne diseases (CVBDs) including babesiosis, hepatozoonosis, leishmaniasis, filariosis (Dirofilaria immitis, Dirofilaria repens, and Acanthocheilonema reconditum), ehrlichiosis (Ehrlichia canis), and anaplasmosis (Anaplasma platys) in stray dogs. The study material consisted of 133 asymptomatic female (n = 96) and male (n = 37) stray dogs (≤1 year old, n = 16 and 1-6 years old, n = 117) housed in the Animal Care and Rehabilitation Center, Erzurum, Northeastern Turkey. Conventional and nested PCR were performed on blood samples to detect Babesia spp., Leishmania spp., Hepatozoon spp., D. immitis, D. repens, A. reconditum, E. canis, and A. platys. Sex and age association with the pathogen prevalence was determined using X 2 statistics. The positivity rate for at least one CVBD pathogen was 48.9% (65/133). DNA of B. canis, Hepatozoon spp., H. canis, D. immitis, and E. canis were detected in 5.3% (7/133), 27.1% (36/133), 5.3% (7/133), 1.5% (2/133), and 9.8% (13/133) of the dogs, respectively. Leishmania spp., D. repens, A. reconditum, and A. platys DNA were not detected. Mixed pathogens were determined in seven (10.8%) of the infected dogs, with predominant involvement of Hepatozoon spp. or H. canis. The pathogen prevalence did not vary by sex or age. Nucleotide blast analysis of Erzurum isolates showed 99.8-100% identities with the corresponding reference isolates. This study indicates presence of five CVB pathogens, including the first report of E. canis, in stray dogs in Erzurum, Turkey.

Survey of patient dosimetry for head and neck cancer patients undergoing external radiotherapy treatment: a study from northeastern hospitals of India.

PubMed

Sharma, Arunkumar B; Singh, Tomcha Th; Singh, Khelendra N; Gartia, R K

2009-01-01

To study dosimetry of patients during the external radiotherapy of head and neck cancers from different hospitals of the northeastern region (NER) of India. 35 confirmed cases of head and neck cancers reporting to three different hospitals in the NER of India who underwent radiation treatment were the materials for the study. Dosimetry was carried out at 8(eight) anatomical points to these patients, namely, target (entrance and exit points), forehead, chest, abdomen, gonad, arm, and leg respectively by thermoluminescence (TL) as well as optically stimulated luminescence (OSL) dosimeters. Unlike conventional appliances, we used common iodized salt as TL/OSL phosphor. Patient dosimetry was found to vary with an average of 1.17 +/- 0.39 Sv at forehead, 1.24 +/- 0.39 Sv at chest, 0.52 +/- 0.13 Sv at gonad to a minimum of 0.26 +/- 0.07 Sv at leg areas when exposed to a cumulative dose of 65 Sv at the target. Maximum dose received from a stray radiation is about 1.5 Sv at forehead/chest and dosimetry of patient among the three centers is not significantly different at the 5% level of probability.

Progress on ITER Diagnostic Integration

NASA Astrophysics Data System (ADS)

Johnson, David; Feder, Russ; Klabacha, Jonathan; Loesser, Doug; Messineo, Mike; Stratton, Brentley; Wood, Rick; Zhai, Yuhu; Andrew, Phillip; Barnsley, Robin; Bertschinger, Guenter; Debock, Maarten; Reichle, Roger; Udintsev, Victor; Vayakis, George; Watts, Christopher; Walsh, Michael

2013-10-01

On ITER, front-end components must operate reliably in a hostile environment. Many will be housed in massive port plugs, which also shield the machine from radiation. Multiple diagnostics reside in a single plug, presenting new challenges for developers. Front-end components must tolerate thermally-induced stresses, disruption-induced mechanical loads, stray ECH radiation, displacement damage, and degradation due to plasma-induced coatings. The impact of failures is amplified due to the difficulty in performing robotic maintenance on these large structures. Motivated by needs to minimize disruption loads on the plugs, standardize the handling of shield modules, and decouple the parallel efforts of the many parties, the packaging strategy for diagnostics has recently focused on the use of 3 vertical shield modules inserted from the plasma side into each equatorial plug structure. At the front of each is a detachable first wall element with customized apertures. Progress on US equatorial and upper plugs will be used as examples, including the layout of components in the interspace and port cell regions. Supported by PPPL under contract DE-AC02-09CH11466 and UT-Battelle, LLC under contract DE-AC05-00OR22725 with the U.S. DOE.

Design of a Rail Gun System for Mitigating Disruptions in Fusion Reactors

NASA Astrophysics Data System (ADS)

Lay, Wei-Siang

Magnetic fusion devices, such as the tokamak, that carry a large amount of current to generate the plasma confining magnetic fields have the potential to lose magnetic stability control. This can lead to a major plasma disruption, which can cause most of the stored plasma energy to be lost to localized regions on the walls, causing severe damage. This is the most important issue for the $20B ITER device (International Thermonuclear Experimental Reactor) that is under construction in France. By injecting radiative materials deep into the plasma, the plasma energy could be dispersed more evenly on the vessel surface thus mitigating the harmful consequences of a disruption. Methods currently planned for ITER rely on the slow expansion of gases to propel the radiative payloads, and they also need to be located far away from the reactor vessel, which further slows down the response time of the system. Rail guns are being developed for aerospace applications, such as for mass transfer from the surface of the moon and asteroids to low earth orbit. A miniatured version of this aerospace technology seems to be particularly well suited to meet the fast time response needs of an ITER disruption mitigation system. Mounting this device close to the reactor vessel is also possible, which substantially increases its performance because the stray magnetic fields near the vessel walls could be used to augment the rail gun generated magnetic fields. In this thesis, the potential viability on Rail Gun based DMS is studied to investigate its projected fast time response capability by design, fabrication, and experiment of an NSTX-U sized rail gun system. Material and geometry based tests are used to find the most suitable armature design for this system for which the desirable attributes are high specific stiffness and high electrical conductivity. With the best material in these studies being aluminum 7075, the experimental Electromagnetic Particle Injector (EPI) system has propelled an aluminum armature (weighing 3g) to a velocity more than 150 m/s within two milliseconds post trigger, consistent with the predicted projection for a system with those parameters. Fixed magnetic field probes and high-speed images capture the velocity profile. To propel the armatures, a 20 mF capacitor bank charged to 2 kV and augmented with external field coils powers the rails. These studies indicate that an EPI based system can indeed operate with a fast response time of less than three milliseconds after an impending disruption is detected, and thus warrants further studies to more fully develop the concept as a back-up option for an ITER DMS.

The legal status of cats in New Zealand: a perspective on the welfare of companion, stray, and feral domestic cats (Felis catus).

PubMed

Farnworth, Mark J; Dye, Nicholson G; Keown, Natasha

2010-01-01

Pinpointing and safeguarding the welfare status of domestic cats is problematic, especially in New Zealand where cats are introduced predators with significant impact on indigenous fauna. Usually the identification of welfare status depends on conservational, legal, and public attitudes that are often contrasting. Cats may rapidly transgress definitions placed on them, confounding attempts to categorize them. In 1 generation, cats can move from a human-dependent state ("stray" or "companion") to wild ("feral"). Often this categorization uses arbitrary behavioral and or situational parameters; consequent treatment and welfare protection for these cats are similarly affected. Terminology used to describe cats is not equitable across research. However, the New Zealand Animal Welfare (Companion Cats) Code of Welfare 2007 seeks to create a new definition of the terms companion, stray, and feral. It distinguishes between cats who live within and without human social constructs. This legislation mandates that cats in human environments or indirectly dependent on humans cannot be classified as feral. Such definitions may prove vital when safeguarding the welfare of free-living domestic cats and cat colonies.

Origins Space Telescope Concept 1: Mid to Far Infrared Mission

NASA Astrophysics Data System (ADS)

Carter, Ruth; DiPirro, Michael; Origins Space Telescope Decadal Mission Study Team

2018-01-01

Origins Space Telescope (OST), is a NASA large mission concept designed to investigate the mid to far infrared sky. It would launch in the mid 2030’s, with mission development and implementation beginning in the mid-2020’s. This poster presents the overall architecture of OST Mission Concept 1. The Concept 1 telescope has a 9-meter diameter off-axis primary mirror, a three-mirror astigmat with a field steering mirror, covering the wavelength range of 6 to 600 µm. Five science instruments are on board the OST observatory for spectroscopy, imaging and coronagraphy. The instruments are the Medium Resolution Survey Spectrometer (MRSS), High Resolution Spectrometer (HRS), Far –IR Imaging and Polarimeter (FIP), Mid-IR Imaging Spectrometer and Coronagraph (MISC) and Heterodyne Instrument (HERO). The instruments are housed in the Instrument Accommodation Module (IAM). The Telescope and IAM are actively cooled to 4 Kelvin by relative high maturity 4 K cryocoolers To limit the Sun, Earth, Moon, and Spacecraft thermal radiation into the 4 K environment, multiple layers of sun shields similar to those used on JWST, are implemented. The sun-shields are also designed to minimize solar pressure and center of gravity discrepancies, thus resulting in the “sugar-scoop” like shape. To prevent locally generated stray light from entering the 4 Kelvin environment during mission operations, a 4 K baffle around the telescope and IAM is used. The OST Observatory will be inserted to a Sun-Earth L2 for mission operations.

Global Noise Studies for CMS Tracker Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arteche, F.; /Zaragoza, ITA; Esteban, C.

The characterization of the noise emissions of DC-DC converters at system level is critical to optimize the design of the detector and define rules for the integration strategy. This paper presents the impedance effects on the noise emissions of DC-DC converters at system level. Conducted and radiated noise emissions at the input and at the output from DC-DC converters have been simulated for different types of power network and FEE impedances. System aspects as granularity, stray capacitances of the system and different working conditions of the DC-DC converters are presented too. This study has been carried out using simulation modelsmore » of noise emissions of DC-DC converters in the real scenario. The results of these studies show important recommendations and criteria to be applied to integrate the DC-DC converters and decrease the system noise level.« less

A microprocessor-based one dimensional optical data processor for spatial frequency analysis

NASA Technical Reports Server (NTRS)

Collier, R. L.; Ballard, G. S.

1982-01-01

A high degree of accuracy was obtained in measuring the spatial frequency spectrum of known samples using an optical data processor based on a microprocessor, which reliably collected intensity versus angle data. Stray light control, system alignment, and angle measurement problems were addressed and solved. The capabilities of the instrument were extended by the addition of appropriate optics to allow the use of different wavelengths of laser radiation and by increasing the travel limits of the rotating arm to + or - 160 degrees. The acquisition, storage, and plotting of data by the computer permits the researcher a free hand in data manipulation such as subtracting background scattering from a diffraction pattern. Tests conducted to verify the operation of the processor using a 25 mm diameter pinhole, a 39.37 line pairs per mm series of multiple slits, and a microscope slide coated with 1.091 mm diameter polystyrene latex spheres are described.

Coupled thermo-elastic and optical performance analyses of a reflective baffle for the BepiColombo laser altimeter (BELA) receiver

NASA Astrophysics Data System (ADS)

Heesel, E.; Weigel, T.; Lochmatter, P.; Rugi Grond, E.

2017-11-01

For the BepiColombo mission, the extreme thermal environment around Mercury requires good heat shields for the instruments. The BepiColombo Laser altimeter (BELA) Receiver will be equipped with a specular reflective baffle in order to limit the solar power impact. The design uses a Stavroudis geometry with alternating elliptical and hyperbolic vanes to reflect radiation at angles >38° back into space. The thermal loads on the baffle lead to deformations, and the resulting changes in the optical performance can be modeled by ray-tracing. Conventional interfaces, such as Zernike surface fitting, fail to provide a proper import of the mechanical distortions into optical models. We have studied alternative models such as free form surface representations and compared them to a simple modeling approach with straight segments. The performance merit is presented in terms of the power rejection ratio and the absence of specular stray-light.

Note: Wide band amplifier for quartz tuning fork sensors with digitally controlled stray capacitance compensation.

PubMed

Peng, Ping; Hao, Lifeng; Ding, Ning; Jiao, Weicheng; Wang, Qi; Zhang, Jian; Wang, Rongguo

2015-11-01

We presented a preamplifier design for quartz tuning fork (QTF) sensors in which the stray capacitance is digitally compensated. In this design, the manually controlled variable capacitor is replaced by a pair of varicap diodes, whose capacitance could be accurately tuned by a bias voltage. A tuning circuit including a single side low power operational amplifier, a digital-to-analog converter, and a microprocessor is also described, and the tuning process can be conveniently carried out on a personal computer. For the design, the noise level was investigated experimentally.

Humoral immune response to Dipylidium caninum infection of stray dogs in Taiwan.

PubMed

Shin, J W; Liao, W T

2002-04-02

Two kinds of homogeneous proglottid, mature and gravid, of Dipylidium caninum were used as the antigens for immunodiagnosis of canine dipylidiosis in stray dogs in Tainan, Taiwan. The ELISA was performed on 30 serum samples; 24 from dipylidiosis, four from ancylostomosis and two from toxocariosis. The ELISA have specificity and sensitive of 100 and 50% for mature proglottid extract, and 75 and 100%, respectively, for gravid proglottid extract. EITB technique showed two major peptide bands of 94.8 and 97.9kDa were recognized in the sera pool of infected dogs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dong-Hwan; Hong, Suk-Ho; National Fusion Research Institute

Plasma characteristics in the far scrape-off layer region of tokamak play a crucial role in the stable plasma operation and its sustainability. Due to the huge facility, electrical diagnostic systems to measure plasma properties have extremely long cable length resulting in large stray current. To overcome this problem, a sideband harmonic method was applied to the Korea Superconducting Tokamak Advanced Research tokamak plasma. The sideband method allows the measurement of the electron temperature and the plasma density without the effect of the stray current. The measured plasma densities are compared with those from the interferometer, and the results show reliabilitymore » of the method.« less

Current polarity-dependent manipulation of antiferromagnetic domains

NASA Astrophysics Data System (ADS)

Wadley, Peter; Reimers, Sonka; Grzybowski, Michal J.; Andrews, Carl; Wang, Mu; Chauhan, Jasbinder S.; Gallagher, Bryan L.; Campion, Richard P.; Edmonds, Kevin W.; Dhesi, Sarnjeet S.; Maccherozzi, Francesco; Novak, Vit; Wunderlich, Joerg; Jungwirth, Tomas

2018-05-01

Antiferromagnets have several favourable properties as active elements in spintronic devices, including ultra-fast dynamics, zero stray fields and insensitivity to external magnetic fields1. Tetragonal CuMnAs is a testbed system in which the antiferromagnetic order parameter can be switched reversibly at ambient conditions using electrical currents2. In previous experiments, orthogonal in-plane current pulses were used to induce 90° rotations of antiferromagnetic domains and demonstrate the operation of all-electrical memory bits in a multi-terminal geometry3. Here, we demonstrate that antiferromagnetic domain walls can be manipulated to realize stable and reproducible domain changes using only two electrical contacts. This is achieved by using the polarity of the current to switch the sign of the current-induced effective field acting on the antiferromagnetic sublattices. The resulting reversible domain and domain wall reconfigurations are imaged using X-ray magnetic linear dichroism microscopy, and can also be detected electrically. Switching by domain-wall motion can occur at much lower current densities than those needed for coherent domain switching.

A low-cost, tunable laser lock without laser frequency modulation

NASA Astrophysics Data System (ADS)

Shea, Margaret E.; Baker, Paul M.; Gauthier, Daniel J.

2015-05-01

Many experiments in optical physics require laser frequency stabilization. This can be achieved by locking to an atomic reference using saturated absorption spectroscopy. Often, the laser frequency is modulated and phase sensitive detection used. This method, while well-proven and robust, relies on expensive components, can introduce an undesirable frequency modulation into the laser, and is not easily frequency tuned. Here, we report a simple locking scheme similar to those implemented previously. We modulate the atomic resonances in a saturated absorption setup with an AC magnetic field created by a single solenoid. The same coil applies a DC field that allows tuning of the lock point. We use an auto-balanced detector to make our scheme more robust against laser power fluctuations and stray magnetic fields. The coil, its driver, and the detector are home-built with simple, cheap components. Our technique is low-cost, simple to setup, tunable, introduces no laser frequency modulation, and only requires one laser. We gratefully acknowledge the financial support of the NSF through Grant # PHY-1206040.

Design and Application of Hybrid Magnetic Field-Eddy Current Probe

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Wallace, Terryl; Newman, Andy; Leser, Paul; Simpson, John

2013-01-01

The incorporation of magnetic field sensors into eddy current probes can result in novel probe designs with unique performance characteristics. One such example is a recently developed electromagnetic probe consisting of a two-channel magnetoresistive sensor with an embedded single-strand eddy current inducer. Magnetic flux leakage maps of ferrous materials are generated from the DC sensor response while high-resolution eddy current imaging is simultaneously performed at frequencies up to 5 megahertz. In this work the design and optimization of this probe will be presented, along with an application toward analysis of sensory materials with embedded ferromagnetic shape-memory alloy (FSMA) particles. The sensory material is designed to produce a paramagnetic to ferromagnetic transition in the FSMA particles under strain. Mapping of the stray magnetic field and eddy current response of the sample with the hybrid probe can thereby image locations in the structure which have experienced an overstrain condition. Numerical modeling of the probe response is performed with good agreement with experimental results.

Superconducting magnetoresistance in ferromagnet/superconductor/ferromagnet trilayers

PubMed Central

Stamopoulos, D.; Aristomenopoulou, E.

2015-01-01

Magnetoresistance is a multifaceted effect reflecting the diverse transport mechanisms exhibited by different kinds of plain materials and hybrid nanostructures; among other, giant, colossal, and extraordinary magnetoresistance versions exist, with the notation indicative of the intensity. Here we report on the superconducting magnetoresistance observed in ferromagnet/superconductor/ferromagnet trilayers, namely Co/Nb/Co trilayers, subjected to a parallel external magnetic field equal to the coercive field. By manipulating the transverse stray dipolar fields that originate from the out-of-plane magnetic domains of the outer layers that develop at coercivity, we can suppress the supercurrent of the interlayer. We experimentally demonstrate a scaling of the magnetoresistance magnitude that we reproduce with a closed-form phenomenological formula that incorporates relevant macroscopic parameters and microscopic length scales of the superconducting and ferromagnetic structural units. The generic approach introduced here can be used to design novel cryogenic devices that completely switch the supercurrent ‘on’ and ‘off’, thus exhibiting the ultimate magnetoresistance magnitude 100% on a regular basis. PMID:26306543

Comparison of the optical depth of total ozone and atmospheric aerosols in Poprad-Gánovce, Slovakia

NASA Astrophysics Data System (ADS)

Hrabčák, Peter

2018-06-01

The amount of ultraviolet solar radiation reaching the Earth's surface is significantly affected by atmospheric ozone along with aerosols. The present paper is focused on a comparison of the total ozone and atmospheric aerosol optical depth in the area of Poprad-Gánovce, which is situated at the altitude of 706 m a. s. l. in the vicinity of the highest mountain in the Carpathian mountains. The direct solar ultraviolet radiation has been measured here continuously since August 1993 using a Brewer MKIV ozone spectrophotometer. These measurements have been used to calculate the total amount of atmospheric ozone and, subsequently, its optical depth. They have also been used to determine the atmospheric aerosol optical depth (AOD) using the Langley plot method. Results obtained by this method were verified by means of comparison with a method that is part of the Brewer operating software, as well as with measurements made by a Cimel sun photometer. Diffuse radiation, the stray-light effect and polarization corrections were applied to calculate the AOD using the Langley plot method. In this paper, two factors that substantially attenuate the flow of direct ultraviolet solar radiation to the Earth's surface are compared. The paper presents results for 23 years of measurements, namely from 1994 to 2016. Values of optical depth were determined for the wavelengths of 306.3, 310, 313.5, 316.8 and 320 nm. A statistically significant decrease in the total optical depth of the atmosphere was observed with all examined wavelengths. Its root cause is the statistically significant decline in the optical depth of aerosols.

The Space Technology 5 Avionics System

NASA Technical Reports Server (NTRS)

Speer, Dave; Jackson, George; Stewart, Karen; Hernandez-Pellerano, Amri

2004-01-01

The Space Technology 5 (ST5) mission is a NASA New Millennium Program project that will validate new technologies for future space science missions and demonstrate the feasibility of building launching and operating multiple, miniature spacecraft that can collect research-quality in-situ science measurements. The three satellites in the ST5 constellation will be launched into a sun-synchronous Earth orbit in early 2006. ST5 fits into the 25-kilogram and 24-watt class of very small but fully capable spacecraft. The new technologies and design concepts for a compact power and command and data handling (C&DH) avionics system are presented. The 2-card ST5 avionics design incorporates new technology components while being tightly constrained in mass, power and volume. In order to hold down the mass and volume, and quali& new technologies for fUture use in space, high efficiency triple-junction solar cells and a lithium-ion battery were baselined into the power system design. The flight computer is co-located with the power system electronics in an integral spacecraft structural enclosure called the card cage assembly. The flight computer has a full set of uplink, downlink and solid-state recording capabilities, and it implements a new CMOS Ultra-Low Power Radiation Tolerant logic technology. There were a number of challenges imposed by the ST5 mission. Specifically, designing a micro-sat class spacecraft demanded that minimizing mass, volume and power dissipation would drive the overall design. The result is a very streamlined approach, while striving to maintain a high level of capability, The mission's radiation requirements, along with the low voltage DC power distribution, limited the selection of analog parts that can operate within these constraints. The challenge of qualifying new technology components for the space environment within a short development schedule was another hurdle. The mission requirements also demanded magnetic cleanliness in order to reduce the effect of stray (spacecraft-generated) magnetic fields on the science-grade magnetometer.

Comparison between Modelled and Measured Magnetic Field Scans of Different Planar Coil Topologies for Stress Sensor Applications.

PubMed

Gibbs, Robert; Moreton, Gregory; Meydan, Turgut; Williams, Paul

2018-03-21

The investigation of planar coils of differing topologies, when combined with a magnetostrictive amorphous ribbon to form a stress-sensitive self-inductor, is an active research area for applications as stress or pressure sensors. Four topologies of planar coil (Circular, Mesh, Meander, and Square) have been constructed using copper track on 30 mm wide PCB substrate. The coils are energized to draw 0.4 A and the resulting magnetic field distribution is observed with a newly developed three-dimensional magnetic field scanner. The system is based on a variably angled Micromagnetics ® STJ-020 tunneling magneto-resistance sensor with a spatial resolution of 5-10 µm and sensitivity to fields of less than 10 A/m. These experimental results are compared with the fields computed by ANSYS Maxwell ® finite element modelling of the same topologies. Measured field shape and strength correspond well with the results of modelling, including direct observation of corner and edge effects. Three-dimensional analysis of the field shape produced by the square coil, isolating the components H ( x ) and H ( z ) , is compared with the three-dimensional field solutions from modelling. The finite element modelling is validated and the accuracy and utility of the new system for three-dimensional scanning of general stray fields is confirmed.

Comparison between Modelled and Measured Magnetic Field Scans of Different Planar Coil Topologies for Stress Sensor Applications

PubMed Central

Moreton, Gregory

2018-01-01

The investigation of planar coils of differing topologies, when combined with a magnetostrictive amorphous ribbon to form a stress-sensitive self-inductor, is an active research area for applications as stress or pressure sensors. Four topologies of planar coil (Circular, Mesh, Meander, and Square) have been constructed using copper track on 30 mm wide PCB substrate. The coils are energized to draw 0.4 A and the resulting magnetic field distribution is observed with a newly developed three-dimensional magnetic field scanner. The system is based on a variably angled Micromagnetics® STJ-020 tunneling magneto-resistance sensor with a spatial resolution of 5–10 µm and sensitivity to fields of less than 10 A/m. These experimental results are compared with the fields computed by ANSYS Maxwell® finite element modelling of the same topologies. Measured field shape and strength correspond well with the results of modelling, including direct observation of corner and edge effects. Three-dimensional analysis of the field shape produced by the square coil, isolating the components H(x) and H(z), is compared with the three-dimensional field solutions from modelling. The finite element modelling is validated and the accuracy and utility of the new system for three-dimensional scanning of general stray fields is confirmed. PMID:29561809

Groundwater methane in relation to oil and gas development and shallow coal seams in the Denver-Julesburg Basin of Colorado

PubMed Central

Sherwood, Owen A.; Rogers, Jessica D.; Lackey, Greg; Burke, Troy L.; Osborn, Stephen G.; Ryan, Joseph N.

2016-01-01

Unconventional oil and gas development has generated intense public concerns about potential impacts to groundwater quality. Specific pathways of contamination have been identified; however, overall rates of contamination remain ambiguous. We used an archive of geochemical data collected from 1988 to 2014 to determine the sources and occurrence of groundwater methane in the Denver-Julesburg Basin of northeastern Colorado. This 60,000-km2 region has a 60-y-long history of hydraulic fracturing, with horizontal drilling and high-volume hydraulic fracturing beginning in 2010. Of 924 sampled water wells in the basin, dissolved methane was detected in 593 wells at depths of 20–190 m. Based on carbon and hydrogen stable isotopes and gas molecular ratios, most of this methane was microbially generated, likely within shallow coal seams. A total of 42 water wells contained thermogenic stray gas originating from underlying oil and gas producing formations. Inadequate surface casing and leaks in production casing and wellhead seals in older, vertical oil and gas wells were identified as stray gas migration pathways. The rate of oil and gas wellbore failure was estimated as 0.06% of the 54,000 oil and gas wells in the basin (lower estimate) to 0.15% of the 20,700 wells in the area where stray gas contamination occurred (upper estimate) and has remained steady at about two cases per year since 2001. These results show that wellbore barrier failure, not high-volume hydraulic fracturing in horizontal wells, is the main cause of thermogenic stray gas migration in this oil- and gas-producing basin. PMID:27402747

Ghost analysis visualization techniques for complex systems: examples from the NIF Final Optics Assembly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beer, G K; Hendrix, J L; Rowe, J

1998-06-26

The stray light or "ghost" analysis of the National Ignition Facility's (NIP) Final Optics Assembly (FOA) has proved to be one of the most complex ghost analyses ever attempted. The NIF FOA consists of a bundle of four beam lines that: 1) provides the vacuum seal to the target chamber, 2) converts 1ω to 3ω light, 3) focuses the light on the target, 4) separates a fraction of the 3ω beam for energy diagnostics, 5) separates the three wavelengths to diffract unwanted 1ω & 2ω light away from the target, 6) provides spatial beam smoothing, and 7) provides a debrismore » barrier between the target chamber and the switchyard mirrors. The three wavelengths of light and seven optical elements with three diffractive optic surfaces generate three million ghosts through 4 th order. Approximately 24,000 of these ghosts have peak fluence exceeding 1 J/cm 2. The shear number of ghost paths requires a visualization method that allows overlapping ghosts on optics and mechanical components to be summed and then mapped to the optical and mechanical component surfaces in 3D space. This paper addresses the following aspects of the NIF Final Optics Ghost analysis: 1) materials issues for stray light mitigation, 2) limitations of current software tools (especially in modeling diffractive optics), 3) computer resource limitations affecting automated coherent raytracing, 4) folding the stray light analysis into the opto-mechanical design process, 5) analysis and visualization tools from simple hand calculations to specialized stray light analysis computer codes, and 6) attempts at visualizing these ghosts using a CAD model and another using a high end data visualization software approach.« less

Optical Design of the Camera for Transiting Exoplanet Survey Satellite (TESS)

NASA Technical Reports Server (NTRS)

Chrisp, Michael; Clark, Kristin; Primeau, Brian; Dalpiaz, Michael; Lennon, Joseph

2015-01-01

The optical design of the wide field of view refractive camera, 34 degrees diagonal field, for the TESS payload is described. This fast f/1.4 cryogenic camera, operating at -75 C, has no vignetting for maximum light gathering within the size and weight constraints. Four of these cameras capture full frames of star images for photometric searches of planet crossings. The optical design evolution, from the initial Petzval design, took advantage of Forbes aspheres to develop a hybrid design form. This maximized the correction from the two aspherics resulting in a reduction of average spot size by sixty percent in the final design. An external long wavelength pass filter was replaced by an internal filter coating on a lens to save weight, and has been fabricated to meet the specifications. The stray light requirements were met by an extended lens hood baffle design, giving the necessary off-axis attenuation.

Large aperture and wide field of view space telescope for the detection of ultra high energy cosmic rays and neutrinos

NASA Astrophysics Data System (ADS)

Mazzinghi, Piero; Bratina, Vojko; Gambicorti, Lisa; Simonetti, Francesca; Zuccaro Marchi, Alessandro

2017-11-01

New technologies are proposed for large aperture and wide Field of View (FOV) space telescopes dedicated to detection of Ultra High Energy Cosmic Rays and Neutrinos flux, through observation of fluorescence traces in atmosphere and diffused Cerenkov signals. The presented advanced detection system is a spaceborne LEO telescope, with better performance than ground-based observatories, detecting up to 103 - 104 events/year. Different design approaches are implemented, all with very large FOV and focal surface detectors with sufficient segmentation and time resolution to allow precise reconstructions of the arrival direction. In particular, two Schmidt cameras are suggested as an appropriate solution to match most of the optical and technical requirements: large FOV, low f/#, reduction of stray light, optionally flat focal surface, already proven low-cost construction technologies. Finally, a preliminary proposal of a wideFOV retrofocus catadioptric telescope is explained.

High temperature superconductor dc-SQUID microscope with a soft magnetic flux guide

NASA Astrophysics Data System (ADS)

Poppe, U.; Faley, M. I.; Zimmermann, E.; Glaas, W.; Breunig, I.; Speen, R.; Jungbluth, B.; Soltner, H.; Halling, H.; Urban, K.

2004-05-01

A scanning SQUID microscope based on high-temperature superconductor (HTS) dc-SQUIDs was developed. An extremely soft magnetic amorphous foil was used to guide the flux from room temperature samples to the liquid-nitrogen-cooled SQUID sensor and back. The flux guide passes through the pick-up loop of the HTS SQUID, providing an improved coupling of magnetic flux of the object to the SQUID. The device measures the z component (direction perpendicular to the sample surface) of the stray field of the sample, which is rastered with submicron precision in the x-y direction by a motorized computer-controlled scanning stage. A lateral resolution better than 10 µm, with a field resolution of about 0.6 nT Hz-1/2 was achieved for the determination of the position of the current carrying thin wires. The presence of the soft magnetic foil did not significantly increase the flux noise of the SQUID.

Magnetoimpedance biosensor prototype for ferrogel detection

NASA Astrophysics Data System (ADS)

Kurlyandskaya, G. V.; Fernández, E.; Safronov, A. P.; Blyakhman, F. A.; Svalov, A. V.; Burgoa Beitia, A.; Beketov, I. V.

2017-11-01

Ferrogels are composite materials widely introduced in the area of biomedical engineering as magnetic field sensitive transformers. These biomimetic materials can be prepared by incorporating monodomain magnetic nanoparticles into chemically crosslinked hydrogels. The properties of a biomimetic ferrogels taken for the study unlike that of the biological prototype might be set up by the synthesis and can be thoroughly controlled in a physical experiment. In this work we developed a giant magnetoimpedance sensor with a multilayered FeNi/Ti-based sensitive element adapted for ferrogel studies. Ferrogels were synthesized by radical polymerization of acrylamide in a stable aqueous suspension of γ-Fe2O3 MNPs fabricated by laser target evaporation. The magnetoimpedance measurements in initial state and in the presence of ferrogels with concentrations of nanoparticles from 0 to 2.4 wt% in a frequency range of 1-300 MHz allowed a precise characterization of the stray fields of the nanoparticles present in the ferrogel.

Faraday-Shielded dc Stark-Shift-Free Optical Lattice Clock

NASA Astrophysics Data System (ADS)

Beloy, K.; Zhang, X.; McGrew, W. F.; Hinkley, N.; Yoon, T. H.; Nicolodi, D.; Fasano, R. J.; Schäffer, S. A.; Brown, R. C.; Ludlow, A. D.

2018-05-01

We demonstrate the absence of a dc Stark shift in an ytterbium optical lattice clock. Stray electric fields are suppressed through the introduction of an in-vacuum Faraday shield. Still, the effectiveness of the shielding must be experimentally assessed. Such diagnostics are accomplished by applying high voltage to six electrodes, which are grounded in normal operation to form part of the Faraday shield. Our measurements place a constraint on the dc Stark shift at the 10-20 level, in units of the clock frequency. Moreover, we discuss a potential source of error in strategies to precisely measure or cancel nonzero dc Stark shifts, attributed to field gradients coupled with the finite spatial extent of the lattice-trapped atoms. With this consideration, we find that Faraday shielding, complemented with experimental validation, provides both a practically appealing and effective solution to the problem of dc Stark shifts in optical lattice clocks.

Faraday-Shielded dc Stark-Shift-Free Optical Lattice Clock.

PubMed

Beloy, K; Zhang, X; McGrew, W F; Hinkley, N; Yoon, T H; Nicolodi, D; Fasano, R J; Schäffer, S A; Brown, R C; Ludlow, A D

2018-05-04

We demonstrate the absence of a dc Stark shift in an ytterbium optical lattice clock. Stray electric fields are suppressed through the introduction of an in-vacuum Faraday shield. Still, the effectiveness of the shielding must be experimentally assessed. Such diagnostics are accomplished by applying high voltage to six electrodes, which are grounded in normal operation to form part of the Faraday shield. Our measurements place a constraint on the dc Stark shift at the 10^{-20} level, in units of the clock frequency. Moreover, we discuss a potential source of error in strategies to precisely measure or cancel nonzero dc Stark shifts, attributed to field gradients coupled with the finite spatial extent of the lattice-trapped atoms. With this consideration, we find that Faraday shielding, complemented with experimental validation, provides both a practically appealing and effective solution to the problem of dc Stark shifts in optical lattice clocks.

Modular transportable superconducting magnetic energy systems

NASA Technical Reports Server (NTRS)

Lieurance, Dennis; Kimball, Foster; Rix, Craig

1995-01-01

Design and cost studies were performed for the magnet components of mid-size (1-5 MWh), cold supported SMES systems using alternative configurations. The configurations studied included solenoid magnets, which required onsite assembly of the magnet system, and toroid and racetrack configurations which consisted of factory assembled modules. For each configuration, design concepts and cost information were developed for the major features of the magnet system including the conductor, electrical insulation, and structure. These studies showed that for mid-size systems, the costs of solenoid and toroid magnet configurations are comparable and that the specific configuration to be used for a given application should be based upon customer requirements such as limiting stray fields or minimizing risks in development or construction.

System and method for cancelling the effects of stray magnetic fields from the output of a variable reluctance sensor

DOEpatents

Chen, Chingchi; Degner, Michael W.

2002-11-19

A sensor system for sensing a rotation of a sensing wheel is disclosed. The sensor system has a sensing coil in juxtaposition with the sensing wheel. Moreover, the sensing coil has a sensing coil output signal indicative of the rotational speed of the sensing wheel. Further, a cancellation coil is located remotely from the sensing coil and connected in series therewith. Additionally, the cancellation coil has a cancellation coil output signal indicative of an environmental disturbance which is effecting the sensing coil output signal. The cancellation coil output signal operates to cancel the effects of the environmental disturbance on the sensing coil output signal.

Modular transportable superconducting magnetic energy systems

NASA Astrophysics Data System (ADS)

Lieurance, Dennis; Kimball, Foster; Rix, Craig

1995-04-01

Design and cost studies were performed for the magnet components of mid-size (1-5 MWh), cold supported SMES systems using alternative configurations. The configurations studied included solenoid magnets, which required onsite assembly of the magnet system, and toroid and racetrack configurations which consisted of factory assembled modules. For each configuration, design concepts and cost information were developed for the major features of the magnet system including the conductor, electrical insulation, and structure. These studies showed that for mid-size systems, the costs of solenoid and toroid magnet configurations are comparable and that the specific configuration to be used for a given application should be based upon customer requirements such as limiting stray fields or minimizing risks in development or construction.

Pre-clinical Training for New Notes Procedures: From Ex-vivo Models to Virtual Reality Simulators.

PubMed

Gromski, Mark A; Ahn, Woojin; Matthes, Kai; De, Suvranu

2016-04-01

Natural orifice transluminal endoscopic surgery (NOTES) is a newer field of endoscopic surgery that allows for scarless treatment of pathologic entities, using novel transluminal approaches. There has been a shift of focus from a clinical and research standpoint from the development and dissemination of "first-generation" NOTES procedures to "new NOTES" procedures that traverse the mucosa of luminal structures, yet do not stray far into the peritoneal cavity. It has been a challenge to find appropriate and effective ways to train gastroenterologists and surgeons in these novel approaches. We review the importance of simulation in training and discuss available simulation options. Copyright © 2016 Elsevier Inc. All rights reserved.

Field-cycling NMR with high-resolution detection under magic-angle spinning: determination of field-window for nuclear hyperpolarization in a photosynthetic reaction center.

PubMed

Gräsing, Daniel; Bielytskyi, Pavlo; Céspedes-Camacho, Isaac F; Alia, A; Marquardsen, Thorsten; Engelke, Frank; Matysik, Jörg

2017-09-21

Several parameters in NMR depend on the magnetic field strength. Field-cycling NMR is an elegant way to explore the field dependence of these properties. The technique is well developed for solution state and in relaxometry. Here, a shuttle system with magic-angle spinning (MAS) detection is presented to allow for field-dependent studies on solids. The function of this system is demonstrated by exploring the magnetic field dependence of the solid-state photochemically induced nuclear polarization (photo-CIDNP) effect. The effect allows for strong nuclear spin-hyperpolarization in light-induced spin-correlated radical pairs (SCRPs) under solid-state conditions. To this end, 13 C MAS NMR is applied to a photosynthetic reaction center (RC) of the purple bacterium Rhodobacter (R.) sphaeroides wildtype (WT). For induction of the effect in the stray field of the magnet and its subsequent observation at 9.4 T under MAS NMR conditions, the sample is shuttled by the use of an aerodynamically driven sample transfer technique. In the RC, we observe the effect down to 0.25 T allowing to determine the window for the occurrence of the effect to be between about 0.2 and 20 T.

Magnetic small-angle neutron scattering of bulk ferromagnets.

PubMed

Michels, Andreas

2014-09-24

We summarize recent theoretical and experimental work in the field of magnetic small-angle neutron scattering (SANS) of bulk ferromagnets. The response of the magnetization to spatially inhomogeneous magnetic anisotropy and magnetostatic stray fields is computed using linearized micromagnetic theory, and the ensuing spin-misalignment SANS is deduced. Analysis of experimental magnetic-field-dependent SANS data of various nanocrystalline ferromagnets corroborates the usefulness of the approach, which provides important quantitative information on the magnetic-interaction parameters such as the exchange-stiffness constant, the mean magnetic anisotropy field, and the mean magnetostatic field due to jumps ΔM of the magnetization at internal interfaces. Besides the value of the applied magnetic field, it turns out to be the ratio of the magnetic anisotropy field Hp to ΔM, which determines the properties of the magnetic SANS cross-section of bulk ferromagnets; specifically, the angular anisotropy on a two-dimensional detector, the asymptotic power-law exponent, and the characteristic decay length of spin-misalignment fluctuations. For the two most often employed scattering geometries where the externally applied magnetic field H0 is either perpendicular or parallel to the wave vector k0 of the incoming neutron beam, we provide a compilation of the various unpolarized, half-polarized (SANSPOL), and uniaxial fully-polarized (POLARIS) SANS cross-sections of magnetic materials.

Fast, high-resolution 3D dosimetry utilizing a novel optical-CT scanner incorporating tertiary telecentric collimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakhalkar, H. S.; Oldham, M.

2008-01-15

This study introduces a charge coupled device (CCD) area detector based optical-computed tomography (optical-CT) scanner for comprehensive verification of radiation dose distributions recorded in nonscattering radiochromic dosimeters. Defining characteristics include: (i) a very fast scanning time of {approx}5 min to acquire a complete three-dimensional (3D) dataset, (ii) improved image formation through the use of custom telecentric optics, which ensures accurate projection images and minimizes artifacts from scattered and stray-light sources, and (iii) high resolution (potentially 50 {mu}m) isotropic 3D dose readout. The performance of the CCD scanner for 3D dose readout was evaluated by comparison with independent 3D readout frommore » the single laser beam OCTOPUS-scanner for the same PRESAGE dosimeters. The OCTOPUS scanner was considered the 'gold standard' technique in light of prior studies demonstrating its accuracy. Additional comparisons were made against calculated dose distributions from the ECLIPSE treatment-planning system. Dose readout for the following treatments were investigated: (i) a single rectangular beam irradiation to investigate small field and very steep dose gradient dosimetry away from edge effects, (ii) a 2-field open beam parallel-opposed irradiation to investigate dosimetry along steep dose gradients, and (iii) a 7-field intensity modulated radiation therapy (IMRT) irradiation to investigate dosimetry for complex treatment delivery involving modulation of fluence and for dosimetry along moderate dose gradients. Dose profiles, dose-difference plots, and gamma maps were employed to evaluate quantitative estimates of agreement between independently measured and calculated dose distributions. Results indicated that dose readout from the CCD scanner was in agreement with independent gold-standard readout from the OCTOPUS-scanner as well as the calculated ECLIPSE dose distribution for all treatments, except in regions within a few millimeters of the edge of the dosimeter, where edge artifact is predominant. Agreement of line profiles was observed, even along steep dose gradients. Dose difference plots indicated that the CCD scanner dose readout differed from the OCTOPUSscanner readout and ECLIPSE calculations by {approx}10% along steep dose gradients and by {approx}5% along moderate dose gradients. Gamma maps (3% dose-difference and 3 mm distance-to-agreement acceptance criteria) revealed agreement, except for regions within 5 mm of the edge of the dosimeter where the edge artifact occurs. In summary, the data demonstrate feasibility of using the fast, high-resolution CCD scanner for comprehensive 3D dosimetry in all applications, except where dose readout is required close to the edges of the dosimeter. Further work is ongoing to reduce this artifact.« less

Prevalence of Toxocara canis infection in dogs in the Warszawa area.

PubMed

Borecka, A; Gawor, J

2000-01-01

The evaluation of Toxocara canis infection in stray dogs from two shelters and private owners dogs in the Warszawa district was the aim of this study. In 1998 five hundred faecal samples were examined. The homeless dogs were found more infected than those kept as pets. T. canis was recorded in 3.4% and 8.8% of stray dogs from the shelters and in 0.4% of animals from flats. The higher prevalence of infection in homeless dogs was due to high density of dogs population, worse environmental condition and irregular anthelmintic treatment in the shelters when compare with housed dogs.

The new design of final optics assembly on SG-III prototype facility

NASA Astrophysics Data System (ADS)

Li, Ping; Zhao, Runchang; Wang, Wei; Jia, Huaiting; Chen, Liangmin; Su, Jingqin

2014-09-01

To improve the performance of SG-III prototype facility (TIL-Technical Integration Line), final optics assembly (FOA) is re-designed. It contains that stray light and focusing ghosts are optimized, operational performance and environments are improved and the total thickness of optics is reduced. With the re-designed FOA, Some performance advantages are achieved. First, the optics damages are mitigated obviously, especially crystals and Focus lens; Second, stray light and focusing ghosts are controlled better that organic contamination sources inside FOA are eliminated; Third, maintenance and operation are more convenient for the atoms environment; Fourth, the focusable power on target is increased for lower B-integral.

Microtextured metals for stray-light suppression in the Clementine startracker

NASA Technical Reports Server (NTRS)

Johnson, E. A.

1993-01-01

Anodized blacks for suppressing stray light in optical systems can now be replaced by microscopically textured metal surfaces. An application of these black surfaces to the Clementine star-tracker navigational system, which will be launched in early 1994 to examine the Moon, en route to intercept an asteroid, is detailed. Rugged black surfaces with Lambertian BRDF less than 10(exp -2) srad(sup -1) are critical for suppressing stray light in the star-tracker optical train. Previously available materials spall under launch vibrations to contaminate mirrors and lenses. Microtextured aluminum is nearly as dark, but much less fragile. It is made by differential ion beam sputtering, which generates light-trapping pores and cones slightly smaller than the wavelength to be absorbed. This leaves a sturdy but light-absorbing surface that can survive challenging conditions without generating debris or contaminants. Both seeded ion beams and plasma immersion (from ECR plasmas) extraction can produce these microscopic textures without fragile interfaces. Process parameters control feature size, spacing, and optical effects (THR, BRDF). Both broad and narrow absorption bands can be engineered with tuning for specific wavelengths and applications. Examples are presented characterized by FTIR in reflection librators (0.95 normal emissivity), heat rejection, and enhanced nucleate boiling.

Optical design and stray light analysis for the JANUS camera of the JUICE space mission

NASA Astrophysics Data System (ADS)

Greggio, D.; Magrin, D.; Munari, M.; Zusi, M.; Ragazzoni, R.; Cremonese, G.; Debei, S.; Friso, E.; Della Corte, V.; Palumbo, P.; Hoffmann, H.; Jaumann, R.; Michaelis, H.; Schmitz, N.; Schipani, P.; Lara, L. M.

2015-09-01

The JUICE (JUpiter ICy moons Explorer) satellite of the European Space Agency (ESA) is dedicated to the detailed study of Jupiter and its moons. Among the whole instrument suite, JANUS (Jovis, Amorum ac Natorum Undique Scrutator) is the camera system of JUICE designed for imaging at visible wavelengths. It will conduct an in-depth study of Ganymede, Callisto and Europa, and explore most of the Jovian system and Jupiter itself, performing, in the case of Ganymede, a global mapping of the satellite with a resolution of 400 m/px. The optical design chosen to meet the scientific goals of JANUS is a three mirror anastigmatic system in an off-axis configuration. To ensure that the achieved contrast is high enough to observe the features on the surface of the satellites, we also performed a preliminary stray light analysis of the telescope. We provide here a short description of the optical design and we present the procedure adopted to evaluate the stray-light expected during the mapping phase of the surface of Ganymede. We also use the results obtained from the first run of simulations to optimize the baffle design.

Factors affecting the prevalence of mange-mite infestations in stray dogs of Yucatán, Mexico.

PubMed

Rodriguez-Vivas, R I; Ortega-Pacheco, A; Rosado-Aguilar, J A; Bolio, G M E

2003-07-10

The aim of the present study was to determine the factors affecting the prevalence of mange-mite infestations in stray dogs of Yucatán, Mexico. The study was carried out in 200 stray dogs of Mérida capital city of Yucatán, Mexico. Four samples (head, thoracic-abdominal area, extremities and ear) were taken from each animal by skin scraping and examined microscopically in 10% KOH solution to detect the presence of mites. Mites were also collected from the external ear canal of dogs using cotton-tipped swabs. The prevalence of different mite species was calculated. A primary screening was performed using 2xK contingency tables of exposure variables. All variables with P< or =0.20 were analyzed by a logistic-binomial regression. The overall prevalence was 34%. Demodex canis (23.0%) was the most frequent mite, followed by Sarcoptes scabei var. canis (7.0%) and Otodectes cynotis (3.5%). The following factors were found: body condition (bad, OR: 5.35, CI 95%: 1.66-17.3; regular, OR: 3.72, CI 95%: 1.39-9.99) and the presence of macroscopic lesions of dermatosis (OR: 42.80, CI 95%: 13.65-134.24).

Community perception regarding rabies prevention and stray dog control in urban slums in India.

PubMed

Herbert, Mrudu; Riyaz Basha, S; Thangaraj, Selvi

2012-12-01

The lack of community awareness about rabies control is a major issue that thwarts efforts to prevent human deaths caused by rabies. The objectives of this study were (1) to assess community knowledge and attitudes about rabies, rabies prevention and stray dog control in an urban slum community and (2) to determine the factors that influence rabies awareness in urban slums. Using a systematic random sampling strategy, 185 participants were selected from 8 urban slums. The data were collected by direct interview using a pre-tested, structured questionnaire. In the study population, 74.1% of the participants had heard about rabies, and 54.1% knew that rabies is a fatal disease. Only 33.5% of the interviewees felt that people in the community had a role to play in controlling the stray dog population. Gender, age and educational status were significantly associated with rabies awareness. Our study indicates that there are gaps in the knowledge and attitudes of individuals living in urban slums regarding rabies prevention and control. Efforts to promote awareness should be targeted at men, older people and uneducated individuals. Copyright © 2012 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Improvements to the MST Thomson Scattering Diagnostic

NASA Astrophysics Data System (ADS)

Adams, D. T.; Borchardt, M. T.; den Hartog, D. J.; Holly, D. J.; Kile, T.; Kubala, S. Z.; Jacobson, C. M.; Thomas, M. A.; Wallace, J. P.; Young, W. C.; MST Thomson Scattering Team

2017-10-01

Multiple upgrades to the MST Thomson Scattering diagnostic have been implemented to expand capabilities of the system. In the past, stray laser light prevented electron density measurements everywhere and temperature measurements for -z/a >0.75. To mitigate stray light, a new laser beamline is being commissioned that includes a longer entrance flight tube, close-fitting apertures, and baffles. A polarizer has been added to the collection optics to further reduce stray light. An absolute density calibration using Rayleigh scattering in argon will be performed. An insertable integrating sphere will provide a full-system spectral calibration as well as maps optical fibers to machine coordinates. Reduced transmission of the collection optics due to coatings from plasma-surface interactions is regularly monitored to inform timely replacements of the first lens. Long-wavelength filters have been installed to better characterize non-Maxwellian electron distribution features. Previous work has identified residual photons not described by a Maxwellian distribution during m =0 magnetic bursts. Further effort to characterize the distribution function will be described. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences program under Award No. DE-FC02-05ER54814.

Population differentiation in Pacific salmon: local adaptation, genetic drift, or the environment?

USGS Publications Warehouse

Adkison, Milo D.

1995-01-01

Morphological, behavioral, and life-history differences between Pacific salmon (Oncorhynchus spp.) populations are commonly thought to reflect local adaptation, and it is likewise common to assume that salmon populations separated by small distances are locally adapted. Two alternatives to local adaptation exist: random genetic differentiation owing to genetic drift and founder events, and genetic homogeneity among populations, in which differences reflect differential trait expression in differing environments. Population genetics theory and simulations suggest that both alternatives are possible. With selectively neutral alleles, genetic drift can result in random differentiation despite many strays per generation. Even weak selection can prevent genetic drift in stable populations; however, founder effects can result in random differentiation despite selective pressures. Overlapping generations reduce the potential for random differentiation. Genetic homogeneity can occur despite differences in selective regimes when straying rates are high. In sum, localized differences in selection should not always result in local adaptation. Local adaptation is favored when population sizes are large and stable, selection is consistent over large areas, selective diffeentials are large, and straying rates are neither too high nor too low. Consideration of alternatives to local adaptation would improve both biological research and salmon conservation efforts.

A serological study of Leishmania infantum in dogs of Khorasan Razavi province, Iran.

PubMed

Sabzevari, S; Razmi, G R; Naghibi, A; Khoshnegah, J

2013-10-01

Leishmania infantum is the principal agent of visceral leishmaniosis (kala-azar) in all areas of Iran. The disease is endemic in Fars, Ardabil, East Azerbaijan and Bushehr provinces while it is sporadic in other parts of the country. Dog as a member of canidae family is the main animal reservoir host of kala-azar. The present study was carried out to determine the sero-prevalence of canine leishmaniosis in Mashhad, the capital city of Khorasan Razavi Province, in the north east of Iran. Two-hundred and nine dogs in two different classes including stray and sheepdogs were selected for this cross-sectional study. The blood samples were collected and tested by indirect immunofluorescent antibody test for detection of anti-Leishmania infantum antibodies. The results showed that 16/209 (7.6 %) of blood samples were positive. The sero-prevalence rates in stray and sheepdogs were 11/94 (11.7 %) and 5/115 (4.3 %), respectively (p < 0.05). Based on the results obtained, it is concluded that visceral leishmaniosis is distributed among dogs of this area, also sero-prevalence of canine leishmaniosis in stray dogs higher than sheepdogs.

Effects of stray lights on Faraday rotation measurement for polarimeter-interferometer system on EAST.

PubMed

Zou, Z Y; Liu, H Q; Ding, W X; Chen, J; Brower, D L; Lian, H; Wang, S X; Li, W M; Yao, Y; Zeng, L; Jie, Y X

2018-01-01

A double-pass radially view 11 chords polarimeter-interferometer system has been operated on the experimental advanced superconducting tokamak and provides important current profile information for plasma control. Stray light originating from spurious reflections along the optical path (unwanted reflections from various optical components/mounts and transmissive optical elements such as windows, waveplates, and lens as well as the detectors) and also direct feedback from the retro-reflector used to realize the double-pass configuration can both contribute to contamination of the Faraday rotation measurement accuracy. Modulation of the Faraday rotation signal due to the interference from multiple reflections is observable when the interferometer phase (plasma density) varies with time. Direct reflection from the detector itself can be suppressed by employing an optical isolator consisting of a λ/4-waveplate and polarizer positioned in front of the mixer. A Faraday angle oscillation during the density ramping up (or down) can be reduced from 5°-10° to 1°-2° by eliminating reflections from the detector. Residual modulation arising from misalignment and stray light from other sources must be minimized to achieve accurate measurements of Faraday rotation.

Stray-light analyses of the multielement telescope for imaging and spectroscopy coronagraph on Solar Orbiter

NASA Astrophysics Data System (ADS)

Sandri, Paolo; Fineschi, Silvano; Romoli, Marco; Taccola, Matteo; Landini, Federico; Da Deppo, Vania; Naletto, Giampiero; Morea, Danilo; Naughton, Denis; Antonucci, Ester

2018-01-01

The modeling of the scattering phenomena for the multielement telescope for imaging and spectroscopy (METIS) coronagraph on board the European Space Agency Solar Orbiter is reported. METIS is an inverted occultation coronagraph including two optical paths: the broadband imaging of the full corona in linearly polarized visible-light (580 to 640 nm) and the narrow-band imaging of the full corona in the ultraviolet Lyman-α (121.6 nm). METIS will have the unique opportunity of observing the solar outer atmosphere as close to the Sun as 0.28 AU and from up to 35 deg out-of-ecliptic. The stray-light simulations performed on the UV and VL channels of the METIS analyzing the contributors of surface microroughness, particulate contamination, cosmetic defects, and diffraction are reported. The results obtained with the nonsequential modality of Zemax OpticStudio are compared with two different approaches: the Monte Carlo ray trace with Advanced Systems Analysis Program (ASAP®) and a semianalytical model. The results obtained with the three independently developed approaches are in considerable agreement and show compliance to the requirement of stray-light level for both the UV and VL channels.

Current status of L. infantum infection in stray cats in the Madrid region (Spain): implications for the recent outbreak of human leishmaniosis?

PubMed

Miró, Guadalupe; Rupérez, Cristina; Checa, Rocío; Gálvez, Rosa; Hernández, Leticia; García, Manuel; Canorea, Isabel; Marino, Valentina; Montoya, Ana

2014-03-24

Since 2009, the incidence of human leishmaniosis in the SW of the Madrid region has been unusually high. Although dogs are the main reservoir for this disease, a role played by dogs in this outbreak has been ruled out and investigators are now considering other hosts (eg. cats, rabbits, hares) as possible alternative reservoirs.This study was designed to examine the Leishmania infantum status of stray cats in Madrid to assess its possible implications in the human leishmaniosis outbreak. 346 captured stray cats were tested for antibodies against L. infantum by the indirect fluorescent antibody technique (IFAT) and nested-PCR methods were used to detect Leishmania DNA in blood samples of cats testing seropositive for L. infantum and/or retroviruses infection. Cats were also tested for Toxoplasma gondii using the direct agglutination test (DAT) and feline leukemia virus (FeLV) antigen and feline immunodeficiency virus (FIV) antibodies (PetChek* FIV/FeLV). The presence of intestinal parasites was determined using a routine coprological method. The seroprevalence of L. infantum infection (cut off ≥ 1/100) was 3.2% (11/346). However, it was not possible to amplify Leishmania DNA in any of the blood samples. Seropositivity was not associated with sex, age, capture site, clinical status, retrovirus infection or T. gondii seropositivity. Of the 11 cats seropositive for L. infantum, 3 also tested positive for FIV, none for FeLV and 6 for T. gondii. It should be mentioned that the prevalence of FeLV p27 antigen was 4% and of FIV antibody was 9.2%. Although the seroprevalence of T. gondii was quite high at 53.5%, no T. gondii oocysts were found in any of the faeces samples analysed (n = 287). In contrast, intestinal parasites were detected in 76 (26.5%) samples, Toxocara cati being the most prevalent. Our results suggest a stable L. infantum infection situation among the stray cats of the Madrid area; the disease is uncommon and no clinical cases have been reported to date. The detection of other zoonotic parasites such as T. gondii and T. cati in stray cats indicates a need to adopt strict control measures in this population.

Advanced space propulsion thruster research

NASA Technical Reports Server (NTRS)

Wilbur, P. J.

1981-01-01

Experiments showed that stray magnetic fields can adversely affect the capacity of a hollow cathode neutralizer to couple to an ion beam. Magnetic field strength at the neutralizer cathode orifice is a crucial factor influencing the coupling voltage. The effects of electrostatic accelerator grid aperture diameters on the ion current extraction capabilities were examined experimentally to describe the divergence, deflection, and current extraction capabilities of grids with the screen and accelerator apertures displaced relative to one another. Experiments performed in orificed, mercury hollow cathodes support the model of field enhanced thermionic electron mission from cathode inserts. Tests supported the validity of a thermal model of the cathode insert. A theoretical justification of a Saha equation model relating cathode plasma properties is presented. Experiments suggest that ion loss rates to discharge chamber walls can be controlled. A series of new discharge chamber magnetic field configurations were generated in the flexible magnetic field thruster and their effect on performance was examined. A technique used in the thruster to measure ion currents to discharge chamber walls is described. Using these ion currents the fraction of ions produced that are extracted from the discharge chamber and the energy cost of plasma ions are computed.

Magnetoresistance engineering and singlet/triplet switching in InAs nanowire quantum dots with ferromagnetic sidegates

NASA Astrophysics Data System (ADS)

Fábián, G.; Makk, P.; Madsen, M. H.; Nygârd, J.; Schönenberger, C.; Baumgartner, A.

2016-11-01

We present magnetoresistance (MR) experiments on an InAs nanowire quantum dot device with two ferromagnetic sidegates (FSGs) in a split-gate geometry. The wire segment can be electrically tuned to a single dot or to a double dot regime using the FSGs and a backgate. In both regimes we find a strong MR and a sharp MR switching of up to 25% at the field at which the magnetizations of the FSGs are inverted by the external field. The sign and amplitude of the MR and the MR switching can both be tuned electrically by the FSGs. In a double dot regime close to pinch-off we find two sharp transitions in the conductance, reminiscent of tunneling MR (TMR) between two ferromagnetic contacts, with one transition near zero and one at the FSG switching fields. These surprisingly rich characteristics we explain in several simple resonant tunneling models. For example, the TMR-like MR can be understood as a stray-field controlled transitions between singlet and triplet double dot states. Such local magnetic fields are the key elements in various proposals to engineer novel states of matter and may be used for testing electron spin based Bell inequalities.

Permanent Magnet Ecr Plasma Source With Magnetic Field Optimization

DOEpatents

Doughty, Frank C.; Spencer, John E.

2000-12-19

In a plasma-producing device, an optimized magnet field for electron cyclotron resonance plasma generation is provided by a shaped pole piece. The shaped pole piece adjusts spacing between the magnet and the resonance zone, creates a convex or concave resonance zone, and decreases stray fields between the resonance zone and the workpiece. For a cylindrical permanent magnet, the pole piece includes a disk adjacent the magnet together with an annular cylindrical sidewall structure axially aligned with the magnet and extending from the base around the permanent magnet. The pole piece directs magnetic field lines into the resonance zone, moving the resonance zone further from the face of the magnet. Additional permanent magnets or magnet arrays may be utilized to control field contours on a local scale. Rather than a permeable material, the sidewall structure may be composed of an annular cylindrical magnetic material having a polarity opposite that of the permanent magnet, creating convex regions in the resonance zone. An annular disk-shaped recurve section at the end of the sidewall structure forms magnetic mirrors keeping the plasma off the pole piece. A recurve section composed of magnetic material having a radial polarity forms convex regions and/or magnetic mirrors within the resonance zone.

A numerical experiment on light pollution from distant sources

NASA Astrophysics Data System (ADS)

Kocifaj, M.

2011-08-01

To predict the light pollution of the night-time sky realistically over any location or measuring point on the ground presents quite a difficult calculation task. Light pollution of the local atmosphere is caused by stray light, light loss or reflection of artificially illuminated ground objects or surfaces such as streets, advertisement boards or building interiors. Thus it depends on the size, shape, spatial distribution, radiative pattern and spectral characteristics of many neighbouring light sources. The actual state of the atmospheric environment and the orography of the surrounding terrain are also relevant. All of these factors together influence the spectral sky radiance/luminance in a complex manner. Knowledge of the directional behaviour of light pollution is especially important for the correct interpretation of astronomical observations. From a mathematical point of view, the light noise or veil luminance of a specific sky element is given by a superposition of scattered light beams. Theoretical models that simulate light pollution typically take into account all ground-based light sources, thus imposing great requirements on CPU and MEM. As shown in this paper, a contribution of distant sources to the light pollution might be essential under specific conditions of low turbidity and/or Garstang-like radiative patterns. To evaluate the convergence of the theoretical model, numerical experiments are made for different light sources, spectral bands and atmospheric conditions. It is shown that in the worst case the integration limit is approximately 100 km, but it can be significantly shortened for light sources with cosine-like radiative patterns.

Electron cyclotron resonance heating by magnetic filter field in a negative hydrogen ion source.

PubMed

Kim, June Young; Cho, Won-Hwi; Dang, Jeong-Jeung; Chung, Kyoung-Jae; Hwang, Y S

2016-02-01

The influence of magnetic filter field on plasma properties in the heating region has been investigated in a planar-type inductively coupled radio-frequency (RF) H(-) ion source. Besides filtering high energy electrons near the extraction region, the magnetic filter field is clearly observed to increase the electron temperature in the heating region at low pressure discharge. With increasing the operating pressure, enhancement of electron temperature in the heating region is reduced. The possibility of electron cyclotron resonance (ECR) heating in the heating region due to stray magnetic field generated by a filter magnet located at the extraction region is examined. It is found that ECR heating by RF wave field in the discharge region, where the strength of an axial magnetic field is approximately ∼4.8 G, can effectively heat low energy electrons. Depletion of low energy electrons in the electron energy distribution function measured at the heating region supports the occurrence of ECR heating. The present study suggests that addition of axial magnetic field as small as several G by an external electromagnet or permanent magnets can greatly increase the generation of highly ro-vibrationally excited hydrogen molecules in the heating region, thus improving the performance of H(-) ion generation in volume-produced negative hydrogen ion sources.

Seroprevalence of Leishmania infection and molecular detection of Leishmania tropica and Leishmania infantum in stray cats of İzmir, Turkey.

PubMed

Can, Hüseyin; Döşkaya, Mert; Özdemir, H Gökhan; Şahar, Esra Atalay; Karakavuk, Muhammet; Pektaş, Bayram; Karakuş, Mehmet; Töz, Seray; Caner, Ayşe; Döşkaya, Aysu Değirmenci; İz, Sultan Gülce; Özbel, Yusuf; Gürüz, Yüksel

2016-08-01

Leishmaniasis caused by more than 20 species of genus Leishmania is transmitted by the bite of infected phlebotomine sand flies. The studies on Leishmania infection in cats is very few in Turkey and therefore we aimed to screen stray cats living in city of İzmir located in western Turkey using nested PCR targeting kinetoplast DNA and serological techniques (ELISA and IFA). Leishmania DNA positive samples were also studied by ITS1 real time PCR. Whole blood and serum samples were obtained from stray cats (n: 1101) living in different counties of İzmir. In serological assays, a serum sample was considered positive in 1:40 dilution in IFA and for ELISA a serum sample was accepted positive when the absorbance value (AV) exceeded the mean AV + Standard Deviation (SD) of the negative control serum samples. According to the results, the seropositivity rates were 10.8% (119/1101) and 15.2% (167/1101) by in house ELISA and IFA, respectively. Among serology coherent samples, the seropositivity rate was 11.1% (116/1047) as detected by both assays after discordant samples (n: 54) were discarded. Of the 1101 stray cats, six (0.54%) were positive by nested PCR while only one of these six samples was positive by ITS1 real time PCR. During PCR, three controls designated as Leishmania infantum, Leishmania tropica, and Leishmania major were used for species identification. According to nested PCR results, L. tropica was identified in two cats (no.76 and 95). In another cat (no. 269), there were two bands in which one of them was well-matched with L. infantum and the other band had ∼850 bp size which does not match with any controls. Remaining three cats (no. 86, 514, and 622) also had the ∼850 bp atypical band size. ITS1 real time PCR detected L. tropica in only one cat (no. 622) which showed an atypical band size in nested PCR. These results indicated that three cats with only one atypical band (no. 86, 514, and 622) and the cat with mixed infection (no. 269) were infected with L. tropica. Altogether, L. tropica was detected in all six DNA positive cats and L. infantum was detected in one cat with mixed infection. In conclusion, although the reservoir role of cats in nature is still unclear the high seroprevalence rate against Leishmania parasites and detecting parasite DNA in stray cats in İzmir indicates that the stray cats are frequently bitten by infected sand flies. Further research activities are required to reveal the frequency of leishmaniasis in cats in different regions of Turkey where Leishmania species are endemic. Copyright © 2016 Elsevier Inc. All rights reserved.

Proposal for a multilayer read-only-memory optical disk structure.

PubMed

Ichimura, Isao; Saito, Kimihiro; Yamasaki, Takeshi; Osato, Kiyoshi

2006-03-10

Coherent interlayer cross talk and stray-light intensity of multilayer read-only-memory (ROM) optical disks are investigated. From results of scalar diffraction analyses, we conclude that layer separations above 10 microm are preferred in a system using a 0.85 numerical aperture objective lens in terms of signal quality and stability in focusing control. Disk structures are optimized to prevent signal deterioration resulting from multiple reflections, and appropriate detectors are determined to maintain acceptable stray-light intensity. In the experiment, quadrilayer and octalayer high-density ROM disks are prepared by stacking UV-curable films onto polycarbonate substrates. Data-to-clock jitters of < or = 7% demonstrate the feasibility of multilayer disk storage up to 200 Gbytes.

Low-volume aluminum and aluminum / titanium nitride bilayer lumped-element kinetic inductance detectors for far-infrared astronomy

NASA Astrophysics Data System (ADS)

Glenn, Jason; Fyhrie, Adalyn; Wheeler, Jordan; Day, Peter K.; Eom, Byeong H.; Leduc, Henry G.

2016-07-01

We present the design and characterization of low-volume, lumped-element aluminum kinetic inductance de- tectors for sensitive far-infrared astronomy observations. The lumped-element kinetic inductance detectors are comprised of meandered inductors that serve as radiation absorbers in parallel with interdigitated capacitors, forming high quality factor resonators. Low inductor volumes lead to low noise equivalent powers by raising quasiparticles densities, and hence responsivities, with respect to larger volumes. Low volumes are achieved with thin (20 nm), narrow (150 nm) inductors. The interdigitated capacitor architecture is designed to mitigate two-level system noise by lowering electric fields in the silicon substrate. Resonance frequencies are in the range of 190 to 500 MHz, with measured internal quality factors in excess of 1 x 105. In a prior incarnation, a titanium nitride layer on top of the aluminum served as a protective layer, but complicated the superconducting proper- ties. These results were reported previously. In the current incarnation, the aluminum layer is left bare with no titanium nitride over-layer. The results for these bare aluminum devices include a yield of 88%, frequency responsivity of 109 W-1, and noise equivalent power of 1 x 10-17 W Hz-1/2 for a 350μm array. There is no evidence for 1=f noise down to at least 200 mHz. The sensitivity is currently limited by white noise, very likely from stray light in the testbed; for this detector design, sensitivities limited by generation-recombination noise in a lower-background environment should be several orders of magnitude lower.

Mounting a thermocouple of type E onto a Cu single crystal for use in a magnetically sensitive environment below 77 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Potzuweit, Alexander; Schaffner, Anuschka; Jänsch, Heinz Julius, E-mail: heinz.jaensch@physik.uni-marburg.de

2014-09-01

Type E thermocouples show magnetic effects at liquid nitrogen temperature and below. This may cause trouble in experiments that are sensitive to magnetic stray fields like nuclear magnetic resonance, photoemission or high resolution electron energy loss spectroscopy. Here, a solution for the temperature measurement of a single crystal is presented. The authors weld a copper rod onto the back side of the single crystal, thereby relocating the sensitive sample from the thermocouple attachment position. They show that it is possible to measure the crystal temperature at the end of the rod while significantly reducing the ferromagnetic influence due to themore » increased distance.« less

The Logarithmic Tail of Néel Walls

NASA Astrophysics Data System (ADS)

Melcher, Christof

We study the multiscale problem of a parametrized planar 180° rotation of magnetization states in a thin ferromagnetic film. In an appropriate scaling and when the film thickness is comparable to the Bloch line width, the underlying variational principle has the form where the reduced stray-field operator Q approximates (-Δ)1/2 as the quality factor Q tends to zero. We show that the associated Néel wall profile u exhibits a very long logarithmic tail. The proof relies on limiting elliptic regularity methods on the basis of the associated Euler-Lagrange equation and symmetrization arguments on the basis of the variational principle. Finally we study the renormalized limit behavior as Q tends to zero.

Design of a magnetic shielding system for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Z. Q.; Chen, Z. J.; Xie, X. F.

2014-11-15

The novel neutron spectrometer TOFED (Time of Flight Enhanced Diagnostics), comprising 90 individual photomultiplier tubes coupled with 85 plastic scintillation detectors through light guides, has been constructed and installed at Experimental Advanced Superconducting Tokamak. A dedicated magnetic shielding system has been constructed for TOFED, and is designed to guarantee the normal operation of photomultiplier tubes in the stray magnetic field leaking from the tokamak device. Experimental measurements and numerical simulations carried out employing the finite element method are combined to optimize the design of the magnetic shielding system. The system allows detectors to work properly in an external magnetic fieldmore » of 200 G.« less

Modular transportable superconducting magnetic Energy Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lieurance, D.; Kimball, F.; Rix, C.

1994-12-31

Design and cost studies were performed for the magnet components of mid-size (1-5 MWh), cold supported SMES systems using alternative configurations. The configurations studied included solenoid magnets, which required onsite assembly of the magnet system, and toroid and racetrack configurations which consisted of factory assembled modules. For each configuration, design concepts and cost information were developed for the major features of the magnet system including the conductor, electrical insulation, and structure. These studies showed that for mid-size systems, the costs of solenoid and toroid magnet configurations are comparable and that the specific configuration to be used for a given applicationmore » should be based upon customer requirements such as limiting stray fields or minimizing risks in development or construction.« less

Space mapping method for the design of passive shields

NASA Astrophysics Data System (ADS)

Sergeant, Peter; Dupré, Luc; Melkebeek, Jan

2006-04-01

The aim of the paper is to find the optimal geometry of a passive shield for the reduction of the magnetic stray field of an axisymmetric induction heater. For the optimization, a space mapping algorithm is used that requires two models. The first is an accurate model with a high computational effort as it contains finite element models. The second is less accurate, but it has a low computational effort as it uses an analytical model: the shield is replaced by a number of mutually coupled coils. The currents in the shield are found by solving an electrical circuit. Space mapping combines both models to obtain the optimal passive shield fast and accurately. The presented optimization technique is compared with gradient, simplex, and genetic algorithms.

Micrometric periodic assembly of magnetotactic bacteria and magnetic nanoparticles using audio tapes

NASA Astrophysics Data System (ADS)

Godoy, M.; Moreno, A. J.; Jorge, G. A.; Ferrari, H. J.; Antonel, P. S.; Mietta, J. L.; Ruiz, M.; Negri, R. M.; Pettinari, M. J.; Bekeris, V.

2012-02-01

We report micrometric periodic assembly of live and dead magnetotactic bacteria, Magnetospirillum magneticum AMB-1, which synthesize chains of magnetic nanoparticles inside their bodies, and of superparamagnetic Fe3O4 and ferromagnetic CoFe2O4 nanoparticles in aqueous suspensions using periodically magnetized audio tapes. The distribution of the stray magnetic field at the surface of the tapes was determined analytically and experimentally by magneto-optic imaging. Calculations showed that the magnetic field close to the tape surface was of the order of 100 mT, and the magnetic field gradient was larger than 1 T mm-1. Drops of aqueous solutions were deposited on the tapes, and bacteria and particles were trapped at locations where magnetic energy is minimized, as observed using conventional optical microscopy. Suspensions of M. magneticum AMB-1 treated with formaldehyde and kanamycin were studied, and patterns of trapped dead bacteria indicated that magnetic forces dominate over self-propelling forces in these experiments, in accordance with calculated values. The behavior of the different types of samples is discussed.

Fast switching and signature of efficient domain wall motion driven by spin-orbit torques in a perpendicular anisotropy magnetic insulator/Pt bilayer

NASA Astrophysics Data System (ADS)

Avci, Can Onur; Rosenberg, Ethan; Baumgartner, Manuel; Beran, Lukáš; Quindeau, Andy; Gambardella, Pietro; Ross, Caroline A.; Beach, Geoffrey S. D.

2017-08-01

We report fast and efficient current-induced switching of a perpendicular anisotropy magnetic insulator thulium iron garnet by using spin-orbit torques (SOT) from the Pt overlayer. We first show that, with quasi-DC (10 ms) current pulses, SOT-induced switching can be achieved with an external field as low as 2 Oe, making TmIG an outstanding candidate to realize efficient switching in heterostructures that produce moderate stray fields without requiring an external field. We then demonstrate deterministic switching with fast current pulses (≤20 ns) with an amplitude of ˜1012 A/m2, similar to all-metallic structures. We reveal that, in the presence of an initially nucleated domain, the critical switching current is reduced by up to a factor of five with respect to the fully saturated initial state, implying efficient current-driven domain wall motion in this system. Based on measurements with 2 ns-long pulses, we estimate the domain wall velocity of the order of ˜400 m/s per j = 1012 A/m2.

Effect of Discontinuities and Penetrations on the Shielding Efficacy of High Temperature Superconducting Magnetic Shields

NASA Astrophysics Data System (ADS)

Hatwar, R.; Kvitkovic, J.; Herman, C.; Pamidi, S.

2015-12-01

High Temperature Superconducting (HTS) materials have been demonstrated to be suitable for applications in shielding of both DC and AC magnetic fields. Magnetic shielding is required for protecting sensitive instrumentation from external magnetic fields and for preventing the stray magnetic fields produced by high power density equipment from affecting neighbouring devices. HTS shields have high current densities at relatively high operating temperatures (40-77 K) and can be easily fabricated using commercial HTS conductor. High current densities in HTS materials allow design and fabrication of magnetic shields that are lighter and can be incorporated into the body and skin of high power density devices. HTS shields are particularly attractive for HTS devices because a single cryogenic system can be used for cooling the device and the associated shield. Typical power devices need penetrations for power and signal cabling and the penetrations create discontinuities in HTS shields. Hence it is important to assess the effect of the necessary discontinuities on the efficacy of the shields and the design modifications necessary to accommodate the penetrations.

Magnetometry of micro-magnets with electrostatically defined Hall bars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lachance-Quirion, Dany; Camirand Lemyre, Julien; Bergeron, Laurent

2015-11-30

Micro-magnets are key components for quantum information processing with individual spins, enabling arbitrary rotations and addressability. In this work, characterization of sub-micrometer sized CoFe ferromagnets is performed with Hall bars electrostatically defined in a two-dimensional electron gas. Due to the ballistic nature of electron transport in the cross junction of the Hall bar, anomalies such as the quenched Hall effect appear near zero external magnetic field, thus hindering the sensitivity of the magnetometer to small magnetic fields. However, it is shown that the sensitivity of the diffusive limit can be almost completely restored at low temperatures using a large currentmore » density in the Hall bar of about 10 A/m. Overcoming the size limitation of conventional etched Hall bars with electrostatic gating enables the measurement of magnetization curves of 440 nm wide micro-magnets with a signal-to-noise ratio above 10{sup 3}. Furthermore, the inhomogeneity of the stray magnetic field created by the micro-magnets is directly measured using the gate-voltage-dependent width of the sensitive area of the Hall bar.« less

Nuclear Spin Dependent Parity Violation in Diatomic Molecules

NASA Astrophysics Data System (ADS)

Cahn, Sidney; Altuntas, Emine; Ammon, Jeffrey; Demille, David

2015-10-01

Nuclear spin-dependent parity violation (NSD-PV) effects arise from the exchange of the Z0 boson between electrons and the nucleus and from the interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The anapole moment grows as A2/3 of the nucleus,while the Z0 coupling is independent of A. We study NSD-PV effects using diatomic molecules, where signals are dramatically amplified by bringing rotational levels of opposite parity close to degeneracy in a strong magnetic field. Using a Stark-interference technique, we measure the NSD-PV interaction matrix element. We present results that demonstrate statistical sensitivity to NSD-PV effects surpassing that of any previous atomic parity violation measurement, using the test system 138Ba19F. We also discuss improvements on investigations of systematics due to non-reversing stray E-fields, Enr together with B-field inhomogeneities, and short-term prospects for measuring the nuclear anapole moment of 137Ba. In the long term, our technique is sufficiently general and sensitive to enable measurements across a broad range of nuclei.

Magnetic domain structure imaging near sample surface with alternating magnetic force microscopy by using AC magnetic field modulated superparamagnetic tip.

PubMed

Cao, Yongze; Nakayama, Shota; Kumar, Pawan; Zhao, Yue; Kinoshita, Yukinori; Yoshimura, Satoru; Saito, Hitoshi

2018-05-03

For magnetic domain imaging with a very high spatial resolution by magnetic force microscopy the tip-sample distance should be as small as possible. However, magnetic imaging near sample surface is very difficult with conventional MFM because the interactive forces between tip and sample includes van der Waals and electrostatic forces along with magnetic force. In this study, we proposed an alternating magnetic force microscopy (A-MFM) which extract only magnetic force near sample surface without any topographic and electrical crosstalk. In the present method, the magnetization of a FeCo-GdOx superparamagnetic tip is modulated by an external AC magnetic field in order to measure the magnetic domain structure without any perturbation from the other forces near the sample surface. Moreover, it is demonstrated that the proposed method can also measure the strength and identify the polarities of the second derivative of the perpendicular stray field from a thin-film permanent magnet with DC demagnetized state and remanent state. © 2018 IOP Publishing Ltd.

A survey of ectoparasite infestations in stray dogs of Gwang-ju City, Republic of Korea.

PubMed

Chee, Jeong Hyun; Kwon, Jung Kee; Cho, Ho Seong; Cho, Kyoung Oh; Lee, Yu Jin; Abd El-Aty, A M; Abdel-Aty, A M; Shin, Sung Shik

2008-03-01

This study was designed to investigate the incidence of ectoparasite infestation among stray dogs in Gwang-ju City, Republic of Korea. A total of 103 stray dogs collected in the Animal Shelter of Gwang-ju City from November 2003 to August 2005 were investigated in this study. Ectoparasites of one or more genera were detected in 45.6% (47 / 103) of the dogs examined for dermatologic lesions and/or skin scrapings (from 3-5 affected areas). Otodectes cynotis was found to be the most frequent parasite (22.3%, 23 / 103), followed by Sarcoptes scabiei var canis (19.4%, 20 / 103), Ctenocephalides canis (6.8%, 7 / 103), Demodex canis (4.9%, 5 / 103), and Trichodectes canis (1.0%, 1 / 103). Monospecific infestation was found in 83.0% (39 / 47) of the affected dogs, whereas concurrent infestations with 2 or more ectoparasites per animal were found in 17.0% (8 / 47) of the affected dogs. Trichodectes canis is reported for the first time in the Republic of Korea. Dogs less than 1 yr old were more heavily infected than other age groups (66.7%), and small-sized dogs of less than 3 kg body weight were more heavily infected than larger dogs (41.7%).

A Survey of Ectoparasite Infestations in Stray Dogs of Gwang-ju City, Republic of Korea

PubMed Central

Chee, Jeong-Hyun; Kwon, Jung-Kee; Cho, Ho-Seong; Cho, Kyoung-Oh; Lee, Yu-Jin; Abd El-Aty, A. M.

2008-01-01

This study was designed to investigate the incidence of ectoparasite infestation among stray dogs in Gwang-ju City, Republic of Korea. A total of 103 stray dogs collected in the Animal Shelter of Gwang-ju City from November 2003 to August 2005 were investigated in this study. Ectoparasites of one or more genera were detected in 45.6% (47 / 103) of the dogs examined for dermatologic lesions and/or skin scrapings (from 3-5 affected areas). Otodectes cynotis was found to be the most frequent parasite (22.%, 23 / 103), followed by Sarcoptes scabiei var canis (19.4%, 20 / 103), Ctenocephalides canis (6.8%, 7 / 103), Demodex canis (4.9%, 5 / 103), and Trichodectes canis (1.0%, 1 / 103). Monospecific infestation was found in 83.0% (39 / 47) of the affected dogs, whereas concurrent infestations with 2 or more ectoparasites per animal were found in 17.0% (8 / 47) of the affected dogs. Trichodectes canis is reported for the first time in the Republic of Korea. Dogs less than 1 yr old were more heavily infected than other age groups (66.7%), and small-sized dogs of less than 3 kg body weight were more heavily infected than larger dogs (41.7%). PMID:18344673

SeaWiFS technical report series. Volume 19: Case studies for SeaWiFS calibration and validation, part 2

NASA Technical Reports Server (NTRS)

Hooker, Stanford B. (Editor); Acker, James G. (Editor); Firestone, Elaine R. (Editor); Mcclain, Charles R.; Fraser, Robert S.; Mclean, James T.; Darzi, Michael; Firestone, James K.; Patt, Frederick S.; Schieber, Brian D.

1994-01-01

This document provides brief reports, or case studies, on a number of investigations and data set development activities sponsored by the Calibration and Validation Team (CVT) within the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project. Chapter 1 is a comparison with the atmospheric correction of Coastal Zone Color Scanner (CZCS) data using two independent radiative transfer formulations. Chapter 2 is a study on lunar reflectance at the SeaWiFS wavelengths which was useful in establishing the SeaWiFS lunar gain. Chapter 3 reports the results of the first ground-based solar calibration of the SeaWiFS instrument. The experiment was repeated in the fall of 1993 after the instrument was modified to reduce stray light; the results from the second experiment will be provided in the next case studies volume. Chapter 4 is a laboratory experiment using trap detectors which may be useful tools in the calibration round-robin program. Chapter 5 is the original data format evaluation study conducted in 1992 which outlines the technical criteria used in considering three candidate formats, the hierarchical data format (HDF), the common data format (CDF), and the network CDF (netCDF). Chapter 6 summarizes the meteorological data sets accumulated during the first three years of CZCS operation which are being used for initial testing of the operational SeaWiFS algorithms and systems and would be used during a second global processing of the CZCS data set. Chapter 7 describes how near-real time surface meteorological and total ozone data required for the atmospheric correction algorithm will be retrieved and processed. Finally, Chapter 8 is a comparison of surface wind products from various operational meteorological centers and field observations. Surface winds are used in the atmospheric correction scheme to estimate glint and foam radiances.

Measurements of magnetic spin excitations in Permalloy microstructures using nitrogen-vacancy magnetometry

NASA Astrophysics Data System (ADS)

Liu, H. J. Jason; Yoon, Seungha; McMichael, Robert

The magnetic properties of nitrogen-vacancy (NV) centers in diamond have enabled emerging applications in fields ranging from cell biology to quantum computing. An NV center is a lattice defect, which behaves like a spin-1 system. NV centers can be prepared in the mz = 0 state by excitation with green light, and the spin state can be detected by the center's fluorescence of red light. The Zeeman splitting of the mz = +/-1 state, combined with a spin coherence time that can approach 1 ms, makes the NV center a sensitive, atom-sized magnetometer. Recently, NV centers have been used to measure spin wave excitations and vortex core dynamics in a Permalloy microdisk. In this talk, we present current NV center measurements on Permalloy micro and nanostructures that build on previous work. Permalloy structures were fabricated on top of a microstrip antenna and the measurements were conducted on a home-built confocal microscope. Preliminary measurements show photoluminescence contrast of ~12% and field detectivity on the order of µT/Hz1/2. This allows for fine field mapping of stray magnetic fields produced by micro and nanostructures, which are typically a few milliteslas in magnitude. Maryland Nanocenter, University of Maryland.

The Focal Plane Assembly for the Athena X-Ray Integral Field Unit Instrument

NASA Technical Reports Server (NTRS)

Jackson, B. D.; Van Weers, H.; van der Kuur, J.; den Hartog, R.; Akamatsu, H.; Argan, A.; Bandler, S. R.; Barbera, M.; Barret, D.; Bruijn, M. P.;

Characteristics and Outcomes of Dogs Admitted into Queensland RSPCA Shelters

PubMed Central

Rand, Jacquie; Morton, John; Paterson, Mandy

2017-01-01

Simple Summary An up-to-date and comprehensive understanding of the characteristics and outcomes of dogs entering shelters is required for implementing targeted strategies to reduce euthanasia of healthy and treatable dogs in Australia. Currently, there are few up-to-date Australian data published on dogs entering shelters, and their outcomes. Of dogs entering the Royal Society for Prevention of Cruelty to Animals, Queensland shelters in 2014, the majority (58%) were strays and 26% were puppies. Only 18% of dogs >6 months were desexed. Most dogs were reclaimed (32%) or adopted (43%). Strategies targeted to locations and breeds overrepresented by admissions are required to reduce shelter admissions, particularly of strays and unwanted litters. Abstract Over 200,000 stray and surrendered dogs are admitted to shelters and municipal facilities in Australia each year, and approximately 20% are euthanized. Contemporary, comprehensive data on the characteristics and outcomes of dogs entering shelters are required to reduce shelter admissions and euthanasia. However, there are currently limited up-to-date data published on dog admission into shelters. A retrospective single cohort study was conducted to describe the characteristics and outcomes of the dog population entering Royal Society for Prevention of Cruelty to Animals, Queensland (RSPCA-QLD) shelters in 2014 (n = 11,967). The majority of dog admissions were strays from the public (24%) or from municipal councils (34%). Just over a quarter of admissions were puppies, 18% of adults (>6 months) were desexed, and the majority of admissions were crossbred dogs (92%). The majority of owner surrenders (86%) were due to human-related reasons. Most dogs were reclaimed (32%) or adopted (43%) and aggression was the most common reason for euthanasia of adult dogs (45%). Low-cost or free desexing and identification programs targeted to areas and breeds contributing to high intake, and increased support services for owners at risk of surrendering their dog, should be trialed to determine their cost effectiveness in reducing shelter admissions and euthanasia. PMID:28862692

Mitigation of Manhole Events Caused by Secondary Cable Failure

NASA Astrophysics Data System (ADS)

Zhang, Lili

"Manhole event" refers to a range of phenomena, such as smokers, fires and explosions which occur on underground electrical infrastructure, primarily in major cities. The most common cause of manhole events is decomposition of secondary cable initiated by an electric fault. The work presented in this thesis addresses various aspects related to the evolution and mitigation of the manhole events caused by secondary cable insulation failure. Manhole events develop as a result of thermal decomposition of organic materials present in the cable duct and manholes. Polymer characterization techniques are applied to intensively study the materials properties as related to manhole events, mainly the thermal decomposition behaviors of the polymers present in the cable duct. Though evolved gas analysis, the combustible gases have been quantitatively identified. Based on analysis and knowledge of field conditions, manhole events is divided into at least two classes, those in which exothermic chemical reactions dominate and those in which electrical energy dominates. The more common form of manhole event is driven by air flow down the duct. Numerical modeling of smolder propagation in the cable duct demonstrated that limiting air flow is effective in reducing the generation rate of combustible gas, in other words, limiting manhole events to relatively minor "smokers". Besides manhole events, another by-product of secondary cable insulation breakdown is stray voltage. The danger to personnel due to stray voltage is mostly caused by the 'step potential'. The amplitude of step potential as a result of various types of insulation defects is calculated using Finite Element Analysis (FEA) program.

Objective straylight assessment of the human eye with a novel device

NASA Astrophysics Data System (ADS)

Schramm, Stefan; Schikowski, Patrick; Lerm, Elena; Kaeding, André; Klemm, Matthias; Haueisen, Jens; Baumgarten, Daniel

2016-03-01

Forward scattered light from the anterior segment of the human eye can be measured by Shack-Hartmann (SH) wavefront aberrometers with limited visual angle. We propose a novel Point Spread Function (PSF) reconstruction algorithm based on SH measurements with a novel measurement devise to overcome these limitations. In our optical setup, we use a Digital Mirror Device as variable field stop, which is conventionally a pinhole suppressing scatter and reflections. Images with 21 different stop diameters were captured and from each image the average subaperture image intensity and the average intensity of the pupil were computed. The 21 intensities represent integral values of the PSF which is consequently reconstructed by derivation with respect to the visual angle. A generalized form of the Stiles-Holladay-approximation is fitted to the PSF resulting in a stray light parameter Log(IS). Additionaly the transmission loss of eye is computed. For the proof of principle, a study on 13 healthy young volunteers was carried out. Scatter filters were positioned in front of the volunteer's eye during C-Quant and scatter measurements to generate straylight emulating scatter in the lens. The straylight parameter is compared to the C-Quant measurement parameter Log(ISC) and scatter density of the filters SDF with a partial correlation. Log(IS) shows significant correlation with the SDF and Log(ISC). The correlation is more prominent between Log(IS) combined with the transmission loss and the SDF and Log(ISC). Our novel measurement and reconstruction technique allow for objective stray light analysis of visual angles up to 4 degrees.

[Design of a Component and Transmission Imaging Spectrometer].

PubMed

Sun, Bao-peng; Zhang, Yi; Yue, Jiang; Han, Jing; Bai, Lian-fa

2015-05-01

In the reflection-based imaging spectrometer, multiple reflection(diffraction) produces stray light and it is difficult to assemble. To address that, a high performance transmission spectral imaging system based on general optical components was developed. On the basis of simple structure, the system is easy to assemble. And it has wide application and low cost compared to traditional imaging spectrometers. All components in the design can be replaced according to different application situations, having high degree of freedom. In order to reduce the influence of stray light, a method based on transmission was introduced. Two sets of optical systems with different objective lenses were simulated; the parameters such as distortion, MTF and aberration.were analyzed and optimized in the ZEMAX software. By comparing the performance of system with different objective len 25 and 50 mm, it can be concluded that the replacement of telescope lens has little effect on imaging quality of whole system. An imaging spectrometer is developed successfully according design parameters. The telescope lens uses double Gauss structures, which is beneficial to reduce field curvature and distortion. As the craftsmanship of transmission-type plane diffraction grating is mature, it can be used without modification and it is easy to assemble, so it is used as beam-split. component of the imaging spectrometer. In addition, the real imaging spectrometer was tested for spectral resolution and distortion. The result demonstrates that the system has good ability in distortion control, and spectral resolution is 2 nm. These data satisfy the design requirement, and obtained spectrum of deuterium lamp through calibrated system are ideal results.

Development of a high permeability cored transintegumental power transformer.

PubMed

Helmicki, A J; Melvin, D M; Henderson, H T; Nebrigic, D; Venkat, R; Glos, D L

1996-01-01

Circulatory support devices require 10-20 W. Currently, several devices are under development for the transmission of this power via transcutaneous transformers, with the secondary implanted subcutaneously and the primary worn externally. Because these devices are air cored, they have relatively large, bulky external appliances, poor coil to coil coupling, and result in significant stray fields passing through adjacent tissues. This article reports on the engineering design of a novel, high permeability cored transformer implanted in a transenteric configuration using an isolated intestinal pouch. Such an approach offers greater energy transmission efficiency, less heat dissipation, less stray electromagnetic energy, and greatly reduced device size. Two competing designs using this concept have been developed and tested. Each consists of the transformer, together with power interface electronics, forming a direct current (DC)/DC resonant converter. Operating frequencies are 90.2 and 14.7 kHz, respectively, with primary/secondary turns ratios of 10/10 and 11/14, respectively. In addition, data interface electronics allows communication across the transformer of up to four signals at a per channel sample rate of 10 Hz. Both designs are able to continuously transmit 25 W at an output level of 12 Vdc into a 5.8 omega load. Calorimetry tests indicate DC to DC efficiencies greater than 75% and coil to coil efficiencies greater than 96%. Total package size for the implantable portion of each device (including sensor internal interface electronics) is less than 40 ml, with a weight weight of less than 100 g. The results of short-term implantation studies have been favorable. Long-term implantation studies currently are under way.

Analytical Model and Optimized Design of Power Transmitting Coil for Inductively Coupled Endoscope Robot.

PubMed

Ke, Quan; Luo, Weijie; Yan, Guozheng; Yang, Kai

2016-04-01

A wireless power transfer system based on the weakly inductive coupling makes it possible to provide the endoscope microrobot (EMR) with infinite power. To facilitate the patients' inspection with the EMR system, the diameter of the transmitting coil is enlarged to 69 cm. Due to the large transmitting range, a high quality factor of the Litz-wire transmitting coil is a necessity to ensure the intensity of magnetic field generated efficiently. Thus, this paper builds an analytical model of the transmitting coil, and then, optimizes the parameters of the coil by enlarging the quality factor. The lumped model of the transmitting coil includes three parameters: ac resistance, self-inductance, and stray capacitance. Based on the exact two-dimension solution, the accurate analytical expression of ac resistance is derived. Several transmitting coils of different specifications are utilized to verify this analytical expression, being in good agreements with the measured results except the coils with a large number of strands. Then, the quality factor of transmitting coils can be well predicted with the available analytical expressions of self- inductance and stray capacitance. Owing to the exact estimation of quality factor, the appropriate coil turns of the transmitting coil is set to 18-40 within the restrictions of transmitting circuit and human tissue issues. To supply enough energy for the next generation of the EMR equipped with a Ø9.5×10.1 mm receiving coil, the coil turns of the transmitting coil is optimally set to 28, which can transfer a maximum power of 750 mW with the remarkable delivering efficiency of 3.55%.

Engineering aspects of design and integration of ECE diagnostic in ITER

DOE PAGES

Udintsev, V. S.; Taylor, G.; Pandya, H. K.B.; ...

2015-03-12

ITER ECE diagnostic [1] needs not only to meet measurement requirements, but also to withstand various loads, such as electromagnetic, mechanical, neutronic and thermal, and to be protected from stray ECH radiation at 170 GHz and other millimeter wave emission, like Collective Thomson scattering which is planned to operate at 60 GHz. Same or similar loads will be applied to other millimetre-wave diagnostics [2], located both in-vessel and in-port plugs. These loads must be taken into account throughout the design phases of the ECE and other microwave diagnostics to ensure their structural integrity and maintainability. The integration of microwave diagnosticsmore » with other ITER systems is another challenging activity which is currently ongoing through port integration and in-vessel integration work. Port Integration has to address the maintenance and the safety aspects of diagnostics, too. Engineering solutions which are being developed to support and to operate ITER ECE diagnostic, whilst complying with safety and maintenance requirements, are discussed in this paper.« less

Relevamiento de HI en el Hemisferio Austral

NASA Astrophysics Data System (ADS)

Arnal, E. M.; Bajaja, E.; Morras, R.; Pöppel, W. G. L.

Un nuevo relevamiento de HI de todo el Hemisferio Austral, comprendido entre -90o <= δ <= -25o, está siendo observado con la antena I del IAR. El mismo es realizado con alta sensibilidad (r.m.s.<= 0.07 K) y alta resolución espectral (1 Km/s). Un total de ~50000 posiciones en el cielo serán observadas, espaciadas en una grilla (lxb) de (0.5o x 0.5o). El intervalo de velocidades cubierto en este relevamiento abarca el rango -450 km/s a +450 km/s en el sistema LSR. Esta base de datos será corregida por efectos de ``stray radiation''. Al presente se ha observado ~70% del total del relevamiento. El mismo es complementario de uno similar realizado en el Hemisferio Norte por Hartman y Burton (1996), con cubrimiento espacial, sensibilidad, resoluciones espaciales y en velocidad, similares a los del IAR. El objetivo final de ambos relevamientos es disponer de una base de datos uniforme en todo el cielo.

Reduction of short wavelength reflectance of multi-wall carbon nanotubes through ultraviolet laser irradiation

NASA Astrophysics Data System (ADS)

Stephens, Michelle S.; Simonds, Brian J.; Yung, Christopher S.; Conklin, Davis; Livigni, David J.; Oliva, Alberto Remesal; Lehman, John H.

2018-05-01

Multi-wall carbon nanotube coatings are used as broadband, low-reflectance absorbers for bolometric applications and for stray light control. They are also used as high emittance blackbody radiators. Irradiation of single wall carbon nanotubes with ultraviolet (UV) laser light has been shown to remove amorphous carbon debris, but there have been few investigations of the interaction of UV light with the more complex physics of multi-wall carbon nanotubes. We present measurements of reflectance and surface morphology before and after exposure of multi-wall carbon nanotube coatings to 248 nm UV laser light. We show that UV exposure reduces the reflectivity at wavelengths below 600 nm and present modeling of the thermal cycling the UV exposure causes at the surface of the carbon nanotubes. This effect can be used to flatten the spectral shape of the reflectivity curve of carbon nanotube absorber coatings used for broadband applications. Finally, we find that the effect of UV exposure depends on the nanotube growth process.

[Distribution of corneal densitometry and its correlation with ocular stray light in healthy eyes].

PubMed

Wu, Zhiqing; Wang, Yan; Zhang, Lin; Wu, Di; Wei, Shengsheng; Su, Xiaolian

2014-01-01

To evaluate and investigate the distribution of corneal density and its Correlation with stray-light value in adult and healthy eyes. A prospective study. Human corneal specimens ranging in age between 20 and 49 years, 116 patients (232 eyes) in total, divided into three groups: 20-29, 30-39, 40-49. Pentacam was used to evaluate total corneal average density and corneal thickness at different diameter around the corneal apex, for corneal density were ≤ 2 mm, >2 mm and ≤ 6 mm, >6 mm and ≤ 10 mm, for corneal thickness were 2 mm, 6 mm and 10 mm, C-quant was used for the stray-light value. Software SPSS 17.0 was used for statistical analysis. Independent samples t testing method was applied to compare the corneal densitometry in different gender and between left eyes and right ones, One-way ANOVA was applied to analyze the differences of corneal density in different age groups and diameters. Pearson correlation analysis was applied to assess the correlation in corneal densitometry values of different diameters, between corneal density of different diameters and age, corneal density of different diameters and corneal thickness of different diameters, corneal density of different diameters and stray-light values. Corneal density for ≤ 2 mm, >2 mm and ≤ 6 mm, >6 mm and ≤ 10 mm diameter are 10.1 ± 1.5(8.2-16.7), 9.3 ± 1.3(7.9-14.2), 9.6 ± 1.7(7.3-16.2). Corneal density of >6 mm and ≤ 10 mm diameter in different age groups were 8.9 ± 1.1, 9.3 ± 1.2, 10.7 ± 2.1, there was a statistical difference in these values (F = 28.939, P = 0.000), and there was a positive correlation between corneal density of >6 mm and ≤ 10 mm diameter and age (r = 0.417, P = 0.000), There were no statistical differences in corneal density values of ≤ 2 mm and >2 mm and ≤ 6 mm in different age groups (F = 1.575, 1.436; P > 0.05), and they had no correlation with age (r = 0.002, 0.048; P > 0.05). There was no statistical difference in corneal density in different gender (t = 1.744, 1.647, -1.181; P > 0.05). Corneal density values of left eyes and right ones had positive relationships at the same diameter (r = 0.977, P = 0.000; r = 0.992, P = 0.000; r = 0.933, P = 0.000), and there were no statistical differences (t = 0.124, 0.199, -0.020;P > 0.05). Between corneal density values of different diameter, there are also some positive relationships, >6 mm and ≤ 10 mm and ≤ 2 mm (r = 0.710, P = 0.000), >6 mm and ≤ 10 mm and >2 mm and ≤ 6 mm (r = 0.748, P = 0.000), ≤ 2 mm and >2 mm and ≤ 6 mm (r = 0.973, P = 0.000), relationship between ≤ 2 mm and >2 mm and ≤ 6 mm, >2 mm and ≤ 6 mm and >6 mm and ≤ 10 mm was obvious, and there was statistical difference in them (F = 17.057, P = 0.000) . The ocular stray light value was 0.95 ± 0.19(0.48-1.38), Corneal density values of ≤ 2 mm, >2 mm and ≤ 6 mm and >6 mm and ≤ 10 mm diameter had positive relationships with the stray light value (r = 0.134,0.146,0.159, P = 0.042,0.026,0.016). Corneal density can be influenced by age, the influence from age infected the corneal density of peripheral more. There was no correlation between corneal density and corneal thickness. There were some influences of corneal density of healthy eyes to the ocular stray light.

Cotunneling and polaronic effect in granular systems

NASA Astrophysics Data System (ADS)

Ioselevich, A. S.; Sivak, V. V.

2017-06-01

We theoretically study the conductivity in arrays of metallic grains due to the variable-range multiple cotunneling of electrons with short-range (screened) Coulomb interaction. The system is supposed to be coupled to random stray charges in the dielectric matrix that are only loosely bounded to their spatial positions by elastic forces. The flexibility of the stray charges gives rise to a polaronic effect, which leads to the onset of Arrhenius-type conductivity behavior at low temperatures, replacing conventional Mott variable-range hopping. The effective activation energy logarithmically depends on temperature due to fluctuations of the polaron barrier heights. We present the unified theory that covers both weak and strong polaron effect regimes of hopping in granular metals and describes the crossover from elastic to inelastic cotunneling.

High frequency measures of OHC nonlinear capacitance (NLC) and their significance: Why measures stray away from predictions

NASA Astrophysics Data System (ADS)

Santos-Sacchi, Joseph

2018-05-01

Measures of membrane capacitance (Cm) can be used to assess important characteristics of voltage-dependent membrane proteins (e.g., channels and transporters). In particular, a protein's time-dependent voltage-sensor charge movement is equivalently represented as a frequency-dependent component of Cm, telling much about the kinetics of the protein's conformational behavior. Recently, we have explored the frequency dependence of OHC voltage-dependent capacitance (aka nonlinear capacitance, NLC) to query rates of conformational switching within prestin (SLC26a5), the cell's lateral membrane molecular motor 1. Following removal of confounding stray capacitance effects, high frequency Cm measures using wide-band stimuli accurately reveal unexpected low pass behavior in prestin's molecular motions.

Magneto-optical imaging of thin magnetic films using spins in diamond

NASA Astrophysics Data System (ADS)

Simpson, David A.; Tetienne, Jean-Philippe; McCoey, Julia M.; Ganesan, Kumaravelu; Hall, Liam T.; Petrou, Steven; Scholten, Robert E.; Hollenberg, Lloyd C. L.

2016-03-01

Imaging the fields of magnetic materials provides crucial insight into the physical and chemical processes surrounding magnetism, and has been a key ingredient in the spectacular development of magnetic data storage. Existing approaches using the magneto-optic Kerr effect, x-ray and electron microscopy have limitations that constrain further development, and there is increasing demand for imaging and characterisation of magnetic phenomena in real time with high spatial resolution. Here we show how the magneto-optical response of an array of negatively-charged nitrogen-vacancy spins in diamond can be used to image and map the sub-micron stray magnetic field patterns from thin ferromagnetic films. Using optically detected magnetic resonance, we demonstrate wide-field magnetic imaging over 100 × 100 μm2 with sub-micron spatial resolution at video frame rates, under ambient conditions. We demonstrate an all-optical spin relaxation contrast imaging approach which can image magnetic structures in the absence of an applied microwave field. Straightforward extensions promise imaging with sub-μT sensitivity and sub-optical spatial and millisecond temporal resolution. This work establishes practical diamond-based wide-field microscopy for rapid high-sensitivity characterisation and imaging of magnetic samples, with the capability for investigating magnetic phenomena such as domain wall and skyrmion dynamics and the spin Hall effect in metals.

New Generation of Superconducting Solenoids for Heavy-Ion Linac Application

NASA Astrophysics Data System (ADS)

Ostroumov, P. N.; Kim, S. H.; Lessner, E. S.; Shepard, K. W.; Laxdal, R. E.

2002-01-01

The beam dynamics of superconducting (SC) heavy-ion linacs operating in the velocity range below 0.4c require a compact accelerating-focusing lattice. The use of SC solenoids together with SC RF resonators within a common cryostat can solve the real-estate problem. The solenoids must have low fringe fields to avoid magnetic-flux capture in the SC RF resonators. Also, incorporating dipole steering coils together with the SC solenoids in one magnet assembly can increase the compactness of the linac lattice. R&D work has been carried out to determine the feasibility of combining the three elements of high solenoid field, low fringe field, and integral dipole field, into one compact package. A 9-Tesla magnet has been initially designed and will be prototyped, with the goal of eventually developing 14-Tesla solenoids of similar design. The most important design issues are: (1) to minimize stray field in the RF cavity region using SC bucking coils and (2) to achieve adequate mechanical stability of the transverse dipole windings in the presence of forces produced by the solenoid/bucking coil assembly. The assembly, including terminals, switches, and protection circuit, are designed to fit inside a 25-cm diameter helium reservoir. The results of the preliminary design of the solenoid, including numerical simulations of the beam dynamics, are reported.

Electrostatically screened, voltage-controlled electrostatic chuck

DOEpatents

Klebanoff, Leonard Elliott

2001-01-01

Employing an electrostatically screened, voltage-controlled electrostatic chuck particularly suited for holding wafers and masks in sub-atmospheric operations will significantly reduce the likelihood of contaminant deposition on the substrates. The electrostatic chuck includes (1) an insulator block having a outer perimeter and a planar surface adapted to support the substrate and comprising at least one electrode (typically a pair of electrodes that are embedded in the insulator block), (2) a source of voltage that is connected to the at least one electrode, (3) a support base to which the insulator block is attached, and (4) a primary electrostatic shield ring member that is positioned around the outer perimeter of the insulator block. The electrostatic chuck permits control of the voltage of the lithographic substrate; in addition, it provides electrostatic shielding of the stray electric fields issuing from the sides of the electrostatic chuck. The shielding effectively prevents electric fields from wrapping around to the upper or front surface of the substrate, thereby eliminating electrostatic particle deposition.

Design of Current Leads for the MICE Coupling Magnet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Li; Li, L.K.; Wu, Hong

2008-04-02

A pair of superconducting coupling magnets will be part of the Muon Ionization Cooling Experiment (MICE). They were designed and will be constructed by the Institute of Cryogenics and Superconductivity Technology, Harbin Institute of Technology, in collaboration with Lawrence Berkeley National Laboratory. The coupling magnet is to be cooled by using cryocoolers at 4.2K. In order to reduce the heat leak to the 4.2K cold mass from 300 K, a pair of current leads composed of conventional copper leads and high temperature superconductor (HTS) leads will be used to supply current to the magnet. This paper presents the optimization ofmore » the conventional conduction-cooled metal leads for the coupling magnet. Analyses on heat transfer down the leads using theoretical method and numerical simulation were carried out. The stray magnetic field around the HTS leads has been calculated and effects of the magnetic field on the performance of the HTS leads has also been analyzed.« less

Optical system design, analysis, and production for advanced technology systems; Proceedings of the Meeting, Innsbruck, Austria, Apr. 15-17, 1986

NASA Technical Reports Server (NTRS)

Fischer, Robert E. (Editor); Rogers, Philip J. (Editor)

1986-01-01

The present conference considers topics in the fields of optical systems design software, the design and analysis of optical systems, illustrative cases of advanced optical system design, the integration of optical designs into greater systems, and optical fabrication and testing techniques. Attention is given to an extended range diffraction-based merit function for lens design optimization, an assessment of technologies for stray light control and evaluation, the automated characterization of IR systems' spatial resolution, a spectrum of design techniques based on aberration theory, a three-field IR telescope, a large aperture zoom lens for 16-mm motion picture cameras, and the use of concave holographic gratings as monochomators. Also discussed are the use of aspherics in optical systems, glass choice procedures for periscope design, the fabrication and testing of unconventional optics, low mass mirrors for large optics, and the diamond grinding of optical surfaces on aspheric lens molds.

Calibrating the SNfactory Integral Field Spectrograph (SNIFS) with SCALA

NASA Astrophysics Data System (ADS)

Küsters, Daniel; Lombardo, Simona; Kowalski, Marek; Aldering, Greg; Nordin, Jakob; Rigault, Mickael

2016-08-01

The SNIFS CALibration Apparatus (SCALA), a device to calibrate the Supernova Integral Field Spectrograph on the University Hawaii 2.2m telescope, was developed and installed in Spring 2014. SCALA produces an artificial planet with a diameter of 1° and a constant surface brightness. The wavelength of the beam can be tuned between 3200 Å and 10000 Å and has a bandwidth of 35 Å. The amount of light injected into the telescope is monitored with NIST calibrated photodiodes. SCALA was upgraded in 2015 with a mask installed at the entrance pupil of the UH88 telescope, ensuring that the illumination of the telescope by stars is similar to that of SCALA. With this setup, a first calibration run was performed in conjunction with the spectrophotometric observations of standard stars. We present first estimates for the expected systematic uncertainties of the in-situ calibration and discuss the results of tests that examine the influence of stray light produced in the optics.

Unravelling the tunable exchange bias-like effect in magnetostatically-coupled two dimensional hybrid (hard/soft) composites

NASA Astrophysics Data System (ADS)

Hierro-Rodriguez, A.; Teixeira, J. M.; Rodriguez-Rodriguez, G.; Rubio, H.; Vélez, M.; Álvarez-Prado, L. M.; Martín, J. I.; Alameda, J. M.

2015-06-01

Hybrid 2D hard-soft composites have been fabricated by combining soft (Co73Si27) and hard (NdCo5) magnetic materials with in-plane and out-of-plane magnetic anisotropies, respectively. They have been microstructured in a square lattice of CoSi anti-dots with NdCo dots within the holes. The magnetic properties of the dots allow us to introduce a magnetostatic stray field that can be controlled in direction and sense by their last saturating magnetic field. The magnetostatic interactions between dot and anti-dot layers induce a completely tunable exchange bias-like shift in the system’s hysteresis loops. Two different regimes for this shift are present depending on the lattice parameter of the microstructures. For large parameters, dipolar magnetostatic decay is observed, while for the smaller one, the interaction between the adjacent anti-dot’s characteristic closure domain structures enhances the exchange bias-like effect as clarified by micromagnetic simulations.

Novel reference radiation fields for pulsed photon radiation installed at PTB.

PubMed

Klammer, J; Roth, J; Hupe, O

2012-09-01

Currently, ∼70 % of the occupationally exposed persons in Germany are working in pulsed radiation fields, mainly in the medical sector. It has been known for a few years that active electronic dosemeters exhibit considerable deficits or can even fail completely in pulsed fields. Type test requirements for dosemeters exist only for continuous radiation. Owing to the need of a reference field for pulsed photon radiation and accordingly to the upcoming type test requirements for dosemeters in pulsed radiation, the Physikalisch-Technische Bundesanstalt has developed a novel X-ray reference field for pulsed photon radiation in cooperation with a manufacturer. This reference field, geared to the main applications in the field of medicine, has been well characterised and is now available for research and type testing of dosemeters in pulsed photon radiation.

The effect of the earth's and stray magnetic fields on mobile mass spectrometer systems.

PubMed

Bell, Ryan J; Davey, Nicholas G; Martinsen, Morten; Short, R Timothy; Gill, Chris G; Krogh, Erik T

2015-02-01

Development of small, field-portable mass spectrometers has enabled a rapid growth of in-field measurements on mobile platforms. In such in-field measurements, unexpected signal variability has been observed by the authors in portable ion traps with internal electron ionization. The orientation of magnetic fields (such as the Earth's) relative to the ionization electron beam trajectory can significantly alter the electron flux into a quadrupole ion trap, resulting in significant changes in the instrumental sensitivity. Instrument simulations and experiments were performed relative to the earth's magnetic field to assess the importance of (1) nonpoint-source electron sources, (2) vertical versus horizontal electron beam orientation, and (3) secondary magnetic fields created by the instrument itself. Electron lens focus effects were explored by additional simulations, and were paralleled by experiments performed with a mass spectrometer mounted on a rotating platform. Additionally, magnetically permeable metals were used to shield (1) the entire instrument from the Earth's magnetic field, and (2) the electron beam from both the Earth's and instrument's magnetic fields. Both simulation and experimental results suggest the predominant influence on directionally dependent signal variability is the result of the summation of two magnetic vectors. As such, the most effective method for reducing this effect is the shielding of the electron beam from both magnetic vectors, thus improving electron beam alignment and removing any directional dependency. The improved ionizing electron beam alignment also allows for significant improvements in overall instrument sensitivity.

Coaxial Electric Heaters

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute

2008-01-01

Coaxial electric heaters have been conceived for use in highly sensitive instruments in which there are requirements for compact heaters but stray magnetic fields associated with heater electric currents would adversely affect operation. Such instruments include atomic clocks and magnetometers that utilize heated atomic-sample cells, wherein stray magnetic fields at picotesla levels could introduce systematic errors into instrument readings. A coaxial electric heater is essentially an axisymmetric coaxial cable, the outer conductor of which is deliberately made highly electrically resistive so that it can serve as a heating element. As in the cases of other axisymmetric coaxial cables, the equal magnitude electric currents flowing in opposite directions along the inner and outer conductors give rise to zero net magnetic field outside the outer conductor. Hence, a coaxial electric heater can be placed near an atomic-sample cell or other sensitive device. A coaxial electric heater can be fabricated from an insulated copper wire, the copper core of which serves as the inner conductor. For example, in one approach, the insulated wire is dipped in a colloidal graphite emulsion, then the emulsion-coated wire is dried to form a thin, uniform, highly electrically resistive film that serves as the outer conductor. Then the film is coated with a protective layer of high-temperature epoxy except at the end to be electrically connected to the power supply. Next, the insulation is stripped from the wire at that end. Finally, electrical leads from the heater power supply are attached to the exposed portions of the wire and the resistive film. The resistance of the graphite film can be tailored via its thickness. Alternatively, the film can be made from an electrically conductive paint, other than a colloidal graphite emulsion, chosen to impart the desired resistance. Yet another alternative is to tailor the resistance of a graphite film by exploiting the fact that its resistance can be changed permanently within about 10 percent by heating it to a temperature above 300 C. A coaxial heater, with electrical leads attached, that has been bent into an almost full circle for edge heating of a circular window is shown. (In the specific application, there is a requirement for a heated cell window, through which an optical beam enters the cell.)

High prevalence of intestinal zoonotic parasites in dogs from Belgrade, Serbia--short communication.

PubMed

Nikolić, Aleksandra; Dimitrijević, Sanda; Katić-Radivojević, Sofija; Klun, Ivana; Bobrć, Branko; Djurković-Djaković, Olgica

2008-09-01

To identify areas of risk for canine-related zoonoses in Serbia, the aim of this study was to provide baseline knowledge about intestinal parasites in 151 dogs (65 household pets, 75 stray and 11 military working dogs) from Belgrade. The following parasites, with their respective prevalences, were detected: Giardia duodenalis (14.6%), Ancylostomatidae (24.5%), Toxocara canis (30.5%), Trichuris vulpis (47.0%) and Taenia-type helminths (6.6%). Of all examined dogs, 75.5% (114/151) were found to harbour at least one parasite species. Of these, mixed infections with up to four species per dog occurred in 44.7% (51/114). Infections with all detected species were significantly higher (p < 0.05) in military working (100%) and stray dogs (93.3%) versus household pets (50.8%). Among all parasites, agents with zoonotic potential including Giardia, Ancylostomatidae and Toxocara were detected in 58.3% (88/151) of all examined dogs with a significant difference (p < 0.05) among the subgroups (100%, 62.7% and 46.2% for military working dogs, stray dogs and household pets, respectively). The high prevalence of zoonotic parasites registered in the dog population from a highly urban area in south-eastern Europe indicates a potential risk to human health. Thus, veterinarians should play an important role in helping to prevent or minimise zoonotic transmission.

Feline immunodeficiency virus and feline leukemia virus: frequency and associated factors in cats in northeastern Brazil.

PubMed

Lacerda, L C; Silva, A N; Freitas, J S; Cruz, R D S; Said, R A; Munhoz, A D

2017-05-10

Our aims were to determine the frequencies of feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) in owned and stray cats in the northeastern region of Brazil, ascertain the status of FeLV infection, and investigate potential associated factors among the owned cats. Blood samples from 200 asymptomatic owned cats and 30 stray cats were processed using nested PCR and commercial immunochromatographic tests to diagnose infections. To evaluate the factors associated with FIV and/or FeLV in owned cats, a semi-structured interview was conducted with each owner about the animal's environment, and these data were subjected to unconditional logistic regression. The frequencies for owned cats were 6% (12/200) and 3% (6/200) for FIV and FeLV, respectively. No owned cat was positive for both viruses. Stray cats showed frequencies of 6.66% (2/30) and 0% (0/30) for FIV and FeLV, respectively. Contact with other cats and living in peri-urban areas were considered to be risk factors (P < 0.05) for FIV. We did not identify any factors associated with infections with FeLV. Our results confirm the presence of these two retroviruses in the region under study. Our use of different diagnostic techniques allowed us to determine the frequency of retroviruses in the feline population more accurately, particularly with regard to infections by FeLV, which have complex pathogenesis.

Prevalence of Echinococcus granulosus taeniasis in stray dogs in the region of Constantine (North-East Algeria).

PubMed

Kohil, K; Benchikh El Fegoun, M C; Gharbi, M

2017-10-01

In North Africa, the domestic dog is regarded as the main reservoir for infection by Echinococcus granulosus of domestic livestock and man. In Algeria, there is very little data on the rate of infestation of dogs, while the prevalence of E. granulosus in the definitive host is a very reliable marker of the potential risk of transmission of cystic tapeworm to humans and livestock. To find out this information, a survey was conducted to assess the prevalence of infection with E. granulosus in stray dogs in the region of Constantine (North-East Algeria). We autopsied and examined 120 stray dogs, 22 (18.3%) of which were infected with E. granulosus, with an average intensity of infestation of 249 worms. The prevalence in the area of survey was evaluated: 15.5% (14/90) and 26.6% (8/30) dogs were parasitized by E. granulosus in urban and rural areas respectively. The influence of age on the rate of infection was very marked. In addition, the appreciation of the prevalence of parasitism by cestodes as a whole showed that 56 (46.6%) animals out of 120 were infected. Facing such a situation of endemic tapeworm parasitism, with a potential risk of transmission to humans, there is an urgent need to take measures to control and break the epidemiological cycles of the parasite.

Helminth Infections of Stray Dogs from Garmsar, Semnan Province, Central Iran

PubMed Central

Eslami, A; Ranjbar-Bahadori, Sh; Meshgi, B; Dehghan, M; Bokaie, S

2010-01-01

Background The aim was to study the gastro-intestinal helminths of stray dogs of Garmsar, Semnan Province, Central Iran, and its impacts on human health and animal production. Methods During 2006, the alimentary tracts of 50 stray dogs at necropsy, selected from villages around Garmsar, were removed, and examined for helminth infections. Subsequently helminths were collected from the contents of each part and scraped sample of small intestines of washed materials in a 100-mesh sieve. To identify the species of helminths, the nematodes were cleared in lactophenol and cestodes were stained using carmine acid. Results Mixed infection was the rule and 40 dogs (80%) harbored more than one species of helminth. Taenia hydatigena was the most prevalent species (80%) followed by Echinococcus granulosus (64%), Toxocara canis (22%), Mesocestoides lineatus (12%), Taenia multiceps (10%) and Dipylidium caninum (4%). The mean intensity of worm infection was low (1–3) except for that of E. granulosus (645). No significant difference was noticed between sex, age and most helminth infections except for that of sex and T. hydatigena (P=0.001) as well as age and T. canis (P=0.001). Conclusion Although human infection with T. hydatigena is unlikely, but other helminths reported in this study are of zoonotic importance, and may pose a threat to community health, and reduce the productions of ruminants harboring taeniid metacestodes. PMID:22347264

Thomson scattering diagnostic system design for the Compact Toroidal Hybrid experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Traverso, P. J., E-mail: pjt0002@auburn.edu; Maurer, D. A.; Ennis, D. A.

2014-11-15

A new Thomson scattering system using standard commercially available components has been designed for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH). The beam, generated by a frequency doubled Continuum PL DLS 2 J Nd:YAG laser, is passed vertically through an entrance Brewster window and an aperturing baffle system to minimize the stray laser light that could enter the collection optics. The beam line has been designed with an 8 m propagation distance to the mid-plane of the CTH device with the beam diameter kept less than 3 mm inside the plasma volume. The beam exits the vacuum systemmore » through another Brewster window and enters a beam dump, again to minimize the stray light in the vacuum chamber. Light collection, spectral processing, and signal detection are accomplished with an f/#∼ 1 aspheric lens, a commercially available Holospec f/1.8 spectrometer, and an Andor iStar DH740-18U-C3 image intensified camera. Spectral rejection of stray laser light, if needed, can be performed with the use of an optional interference filter at the spectrometer input. The system has been developed for initial single point measurements of plasmas with core electron temperatures of approximately 20–300 eV and densities of 5 × 10{sup 18} to 5 × 10{sup 19} m{sup −3} dependent upon operational scenario.« less

UV spectroscopy with the CETUS multi-object spectrometer

NASA Astrophysics Data System (ADS)

Kendrick, Stephen E.; Woodruff, Robert; Hull, Anthony; Heap, Sara; Kutyrev, Alexander; Purves, Lloyd; Danchi, William

2018-01-01

The ultraviolet multi-object spectrograph (MOS) for the Cosmic Evolution Through UV Spectroscopy (CETUS) concept is a slit-based instrument allowing multiple simultaneous observations over a wide field of view. The UV MOS will be able to target up to 100 objects at a time without the issues of confusion with nearby sources or unwanted background like zodiacal stray light. The multiplexing will allow over 100,000 galaxies to be observed over a typical mission lifetime which greatly enhances the scientific yield. The MOS utilizes a next-generation micro-shutter array, an efficient aspheric Offner-like spectrometer design with a convex grating, and nanotube light traps for suppressing unwanted wavelengths. The optical coatings are also designed for optimizing the UV throughput while minimizing out-of-band signal at the detector.

Multiplexing in astrophysics with a UV multi-object spectrometer on CETUS, a probe-class mission study

NASA Astrophysics Data System (ADS)

Kendrick, Stephen E.; Woodruff, Robert A.; Hull, Tony; Heap, Sara R.; Kutyrev, Alexander; Danchi, William; Purves, Lloyd

2017-09-01

The ultraviolet multi-object spectrograph (MOS) for the Cosmic Evolution Through UV Spectroscopy (CETUS) concept1,2 is a slit-based instrument allowing multiple simultaneous observations over a wide field of view. It utilizes a next-generation micro-shutter array, an efficient aspheric Offner spectrometer design with a convex grating, and carbon nanotube light traps for suppressing unwanted wavelengths. The optical coatings are also designed to optimize the UV throughput while minimizing out-of-band signal at the detector. The UV MOS will be able to target up to 100 objects at a time without the issues of confusion with nearby sources or unwanted background like zodiacal stray light. With this multiplexing, the scientific yield of both Probe and Great Observatories will be greatly enhanced.

An Overview of the HST Advanced Camera for Surveys' On-orbit Performance

NASA Astrophysics Data System (ADS)

Hartig, G. F.; Ford, H. C.; Illingworth, G. D.; Clampin, M.; Bohlin, R. C.; Cox, C.; Krist, J.; Sparks, W. B.; De Marchi, G.; Martel, A. R.; McCann, W. J.; Meurer, G. R.; Sirianni, M.; Tsvetanov, Z.; Bartko, F.; Lindler, D. J.

2002-05-01

The Advanced Camera for Surveys (ACS) was installed in the HST on 7 March 2002 during the fourth servicing mission to the observatory, and is now beginning science operations. The ACS provides HST observers with a considerably more sensitive, higher-resolution camera with wider field and polarimetric, coronagraphic, low-resolution spectrographic and solar-blind FUV capabilities. We review selected results of the early verification and calibration program, comparing the achieved performance with the advertised specifications. Emphasis is placed on the optical characteristics of the camera, including image quality, throughput, geometric distortion and stray-light performance. More detailed analyses of various aspects of the ACS performance are presented in other papers at this meeting. This work was supported by a NASA contract and a NASA grant.

Linear bunchers and half-frequency bunching method

NASA Astrophysics Data System (ADS)

Tang, J. Y.; Jiang, J. Z.; Shi, A. M.; Yin, Z. K.; Wang, Y. F.

2000-12-01

A new buncher system consisting of two bunchers has been designed and constructed for HIRFL injector cyclotron, working at the SFC acceleration modes of H=1 and H=3, respectively. The bunchers use saw-tooth RF waveform, but with double-gap drift tube electrodes and single-gap grid electrodes, respectively. The special merit of the design is introduction of the half-frequency bunching mode, utilizing half of the cyclotron RF frequency. With this method, a perfect longitudinal match between the injector SFC and the main cyclotron SSC has been reached theoretically, compared to the original efficiency of 50% for most cases. Detailed studies have been made concerning space charge effects, longitudinal dispersions through the yoke hole and the spiral inflector, and non-linearity in both the RF waveform and the stray electric field of electrodes.

Opto-mechanical architecture of the LISA instrument

NASA Astrophysics Data System (ADS)

Weise, Dennis; Marenaci, Pierangelo; Weimer, Peter; Berger, Marcel; Schulte, Hans R.; Gath, Peter; Johann, Ulrich

2017-11-01

We report on the latest iteration of the baseline opto-mechanical architecture of the LISA instru- ment, which has been developed within the current LISA Mission Formulation study under ESA con- tract. The collective features of the current architec- ture have been consolidated in an extensive trade of various alternative payload configurations, including variants with only one active proof mass per space- craft and the application of "In-Field Pointing" for accommodation of constellation breathing. With respect to the original configuration [1], the newly established architecture most notably distin- guishes itself by the use of an off-axis telescope and a "non-frequency-swap" science interferometer for stray light mitigation, as well as the implementa- tion of ancillary pathlength metrology in terms of an "Optical Truss" and Point Ahead Angle sensing.

Fiber optic and laser sensors X; Proceedings of the Meeting, Boston, MA, Sept. 8-11, 1992

NASA Technical Reports Server (NTRS)

Udd, Eric (Editor); Depaula, Ramon P. (Editor)

1993-01-01

Topics addressed include acoustic and pressure sensors; fiber optic gyros; electric and magnetic field sensors; bend, strain, and temperature sensors; industrial applications of sensors; and processing techniques. Particular attention is given to fiber optic interferometric acoustic sensors for wind tunnel applications, polished coupler and resonator fabrication, second-harmonic detection for rotation sensing in fiber optic gyros, simplified control theory in closed-loop fiber optic gyroscopes, and a Fabry-Perot sensor with digital signal processing for the measurement of magnetostriction. Also discussed are a Bragg fiber laser sensor, commercialization of fiber optic strain gauge systems, thermal ignition in hazardous environments due to stray light from optical fibers, a system for absolute measurements by interferometric sensors, and high-performance interferometric demodulation techniques.

Practical Design Guidelines of qZSI Based Step-Up DC/DC Converter

NASA Astrophysics Data System (ADS)

Zakis, Janis; Vinnikov, Dmitri; Roasto, Indrek; Jalakas, Tanel

2010-01-01

This paper presents some design guidelines for a new voltage fed step-up DC/DC isolated converter. The most significant advantage of proposed converter is voltage buck-boost operation on single stage. The most promising application for proposed converter is in the field of distributed power generation e.g. fuel cells or photovoltaic. The most sensitive issues - such as power losses caused by high currents in the input side of converter and high transient overvoltages across the inverter bridge caused by stray inductances were discussed and solved. The proposals and recommendations to overcome these issues are given in the paper. The Selection and design guidelines of converter elements are proposed and explained. The prototype of proposed converter was built and experimentally tested. Some results are presented and evaluated.

Synchronized Re-Entrant Flux Reversal of Multiple FeSiB Amorphous Wires Having the Larger Output

NASA Astrophysics Data System (ADS)

Takajo, Minoru; Yamasaki, Jiro

Technique to synchronize the re-entrant flux reversal of the multiple magnetostrictive Fe77.5Si7.5B15 amorphous wires was developed using a flux keeper of amorphous ribbons contacted to the wire ends. It is comprehended that the characteristics of the re-entrant flux takes place respectively at almost the same time in the three Fe-Si-B amorphous wires with a diameter of 65, 95μm. This phenomenon can be explained by considering the strong magnetic coupling of wires and amorphous ribbon by stray field from the each wire ends. As a result, the magnitude of the induced voltage in the sense coil is increased in proportion to the multiplication of the number of the wires.

Cooling and stabilization of graphene nanoplatelets in high vacuum

NASA Astrophysics Data System (ADS)

Nagornykh, Pavel

The study of 2D materials is a rapidly growing area of research, where the ability to isolate and probe an individual single-layer specimen is of high importance. The levitation approach serves as a natural solution for this problem and can be used in ways complementary to the standard techniques. Experiments, including study of properties at high or close to melting temperatures, stretching, folding, vibration and functionalization, can be conducted on levitated 2D materials. As a first step towards realization of all these ideas, one needs to develop and test a system allowing for control over the thermal state and orientation of mono-layer flakes. In this thesis, I present the results of implementation of the parametric feedback cooling scheme in a quadrupole ion trap for stabilization and cooling of graphene nanopletelets. I have tested and showed that the feedback allows to stabilize levitated graphene nanoplatelets in high vacuum conditions (<1 microTorr) to have trapped life times longer than a week. Cooling of the center of mass motion to temperatures below 20 K for all translational degrees of freedom was observed. I have also studied the coupling of DC patch potentials, which were found to be present in the high vacuum chamber. Their effect on cooling was studied and the protocol for minimizing the noise coupling created by the DC fields was designed. We have shown that by varying DC voltages on a set of auxiliary DC electrodes, placed near the trap, one can balance out the DC fields and achieve the lowest cooling temperature. The settings corresponding to this temperature were measured to have a slow drift in time. Ability to tune the settings to balance this drift without breaking the vacuum was studied and found to be a viable solution for the drift cancellation. In addition, our effort in characterization of the flakes is presented. It was shown that the flake discharge quantization observed during the initial pumping down of the high vacuum chamber allows to extract absolute values of flake mass and charge. I also mention the issues experienced with estimation of the shape of the flake, as well as its temperature based on an equipartition theorem. Finally, I discuss the preliminary data on the precession and reorientation of the flakes in the presence of circularly polarized light (CPL) and DC stray fields. The dependence of flake orientation on the offset from the nulling settings is observed and is explained in terms of basic model of a solid charged disk in the presence of two torques created by CPL and DC stray fields.

Comparison of solar photospheric bright points between Sunrise observations and MHD simulations

NASA Astrophysics Data System (ADS)

Riethmüller, T. L.; Solanki, S. K.; Berdyugina, S. V.; Schüssler, M.; Martínez Pillet, V.; Feller, A.; Gandorfer, A.; Hirzberger, J.

2014-08-01

Bright points (BPs) in the solar photosphere are thought to be the radiative signatures (small-scale brightness enhancements) of magnetic elements described by slender flux tubes or sheets located in the darker intergranular lanes in the solar photosphere. They contribute to the ultraviolet (UV) flux variations over the solar cycle and hence may play a role in influencing the Earth's climate. Here we aim to obtain a better insight into their properties by combining high-resolution UV and spectro-polarimetric observations of BPs by the Sunrise Observatory with 3D compressible radiation magnetohydrodynamical (MHD) simulations. To this end, full spectral line syntheses are performed with the MHD data and a careful degradation is applied to take into account all relevant instrumental effects of the observations. In a first step it is demonstrated that the selected MHD simulations reproduce the measured distributions of intensity at multiple wavelengths, line-of-sight velocity, spectral line width, and polarization degree rather well. The simulated line width also displays the correct mean, but a scatter that is too small. In the second step, the properties of observed BPs are compared with synthetic ones. Again, these are found to match relatively well, except that the observations display a tail of large BPs with strong polarization signals (most likely network elements) not found in the simulations, possibly due to the small size of the simulation box. The higher spatial resolution of the simulations has a significant effect, leading to smaller and more numerous BPs. The observation that most BPs are weakly polarized is explained mainly by the spatial degradation, the stray light contamination, and the temperature sensitivity of the Fe i line at 5250.2 Å. Finally, given that the MHD simulations are highly consistent with the observations, we used the simulations to explore the properties of BPs further. The Stokes V asymmetries increase with the distance to the center of the mean BP in both observations and simulations, consistent with the classical picture of a production of the asymmetry in the canopy. This is the first time that this has been found also in the internetwork. More or less vertical kilogauss magnetic fields are found for 98% of the synthetic BPs underlining that basically every BP is associated with kilogauss fields. At the continuum formation height, the simulated BPs are on average 190 K hotter than the mean quiet Sun, the mean BP field strength is found to be 1750 G, and the mean inclination is 17°, supporting the physical flux-tube paradigm to describe BPs. On average, the synthetic BPs harbor downflows increasing with depth. The origin of these downflows is not yet understood very well and needs further investigation.

Optimization of fiber-optic/infrared measurement system and spectral modeling for enhanced temperature acquisition from an aluminized polymer membrane

NASA Astrophysics Data System (ADS)

Smith, Christopher M.; Rowley, Matthew J.

2004-04-01

A fiber-optic/infrared (F-O/IR), non-contact temperature measurement system was characterized, and the existing technique for data collection improved, resulting in greater repeatability and precision of data collected. The F-O/IR system is a dual-waveband measurement apparatus that was recently enhanced by the installation of a tuning fork chopper directly into the fiber optical head. This permits a shortened distance between fiber and detector pair, and therefore a stronger signal can be collected. A simple closed box with the inside painted flat black was constructed and used to prevent stray radiation and convection, thus minimizing undesired effects on the measurement process. Analyses of the new data sets demonstrate that system improvements provide a cleaner and more reliable data collection capability. The exponential relationship between detector output voltage and object temperature indicates that the instrument is operating within its nominal range. The overall goal of this project was to develop a reliable technique to measure the temperature of Kapton HN, an aluminized polymer material being studied for potential future NASA missions. A spectral model that emulates the instrument was also developed in this study. Our measurements and characterization of KaptonÓ HN will be incorporated into the spectral model in order to determine the sensitivity of the instrument to background radiation, spectral emittance of Kapton HN, and other parameters that may affect thermal measurements.

EDITORIAL Complexity of advanced radiation therapy necessitates multidisciplinary inquiry into dose reconstruction and risk assessment Complexity of advanced radiation therapy necessitates multidisciplinary inquiry into dose reconstruction and risk assessment

NASA Astrophysics Data System (ADS)

Newhauser, Wayne

2010-07-01

The availability of low-cost, high-performance computing is rapidly transforming the landscape of cancer research. Computational techniques are playing an increasingly important role and have become the third major method of scientific inquiry, supplementing traditional methods of observation and theory. This evolution began in the 1940s when high-performance computing techniques were developed for military applications, including radiation transport calculations. These same basic methods are still widely utilized in a broad spectrum of computational problems in medicine, including radiation cancer therapy (Rogers 2006, Spezi 2010) and radiologic diagnostic imaging (Doi 2006, Kalender 2006). Supercomputing is also now being used to study the genetics and genomics of cancer (Geurts van Kessel 2010), with application to gene sequencing (Mardis 2008), genome-wide association studies (Pearson and Manolio 2008), biomolecular dynamics (Sanbonmatsu and Tung 2007) and systems biology (Wolkenhauer et al 2010). The extensive and growing body of literature is evidence of a remarkable expansion of activity and enormous boost to cancer research from the application of high-performance computing. Early successes were facilitated by inexpensive computing resources and advances in modeling algorithms. Many contemporary models require extensive approximations and phenomenological approaches. In fact, many critical problems remain computationally intractable; the underlying physical and biological processes are simply too complex to model with contemporary theory and computing capacity. In the future, a vast stream of new insights will flow from studies that use increasingly exact models and first-principles approaches. Hence, in the war on cancer the present status of computational research could be summarized as the beginning of the beginning. For these reasons, there is a vital need for scientists and clinicians to periodically discuss progress and future plans regarding computational cancer research, particularly research involving supercomputing. In April 2010, a symposium entitled '4th Joint Symposium on Computational Medical Physics: The Nexus of Research on Cancer, Radiation, and Supercomputing: Dawn of a Golden Age?' was convened at Rice University in Houston, Texas. One objective of this symposium was to provide researchers and clinicians with an overview of recent progress in advanced radiation therapy. Another was to review basic concepts and methods from a wide variety of disciplines related to cancer radiation therapy, including supercomputing, physics, informatics, imaging, and epidemiology. The symposium featured current issues and controversies and, in particular, a review of recent advances in research on proton and photon therapies. Sessions included Current Issues in Proton Therapy for Pediatric Cancers; Current Issues in Advanced Radiotherapy for Prostate Cancer; Charged Particles in Space and Military Applications; Recent Advances in Radiation Epidemiology; Advanced Computing Techniques: Perspectives from Cancer Researchers and Computer Scientists; Radiobiologic, Dosimetric, and Outcomes Modeling; Imaging and Informatics, and a Young Investigators' Symposium. The complete program is available at www.regonline.com/joint_symposium. The symposium was attended by more than 100 delegates who delivered 47 oral presentations. The delegates included leading scientists and clinicians from the fields of epidemiology, particle physics, medical physics, mathematics, oncology, and cancer prevention. This issue of Physics in Medicine and Biology contains 13 original research articles based on selected presentations from the symposium. Each article underwent the journal's usual rigorous peer review process; we are grateful to the many individuals who contributed to this issue, including the publishing editor, board members, referees, and of course the authors, all of whom generously shared their time and expertise. The majority of articles from the symposium are interrelated and focus on dose and risk assessments related to radiation exposures from advanced radiation therapies. These research topics have become increasingly complex and require the combined expertise of researchers with highly specialized and diverse investigational skills. Innovative multidisciplinary teams will be needed to achieve breakthroughs and, ultimately, to translate the research into clinical practice (Disis and Slattery 2010). The symposium's scientific goals included fostering and promoting such multidisciplinary teams, which will work to solve these complex problems and thereby improve cancer outcomes. To help clarify how the 13 articles each contribute to the goal of improving cancer outcomes, a brief digression is necessary. The proportion of patients surviving their cancers for five years or more is large and increasing (Jemal et al 2009). Unfortunately, in survivors who received radiation therapy, the prevalence of radiogenic late effects is likewise large and increasing (cf Altekruse et al 2010, Meadows et al 2009, Hudson et al 2009, Friedman et al 2010), with the potential to become a public health issue of considerable scale (Travis 2006). A multitude of late effects are associated with radiation exposure, including the development of second cancers, cardiac toxicity, cognitive deficits, and musculoskeletal growth abnormalities in children. In modern radiation therapy, much effort is devoted to developing personalized treatments that control the tumor while minimizing acute toxicities to surrounding healthy tissues; comparatively less attention has been paid to minimizing late effects (Durante and Loeffler 2010). In recent years, however, there has been an encouraging increase in research activities seeking to quantify radiation exposures (Stovall et al 2006) and the associated risks of late effects from modern external-beam therapies (Xu et al 2008). In this issue, Zhang et al (2010) report on Monte Carlo and analytical models to predict the stray radiation exposure in a patient receiving proton radiotherapy. In this study, the authors focused on stray neutron radiation that emanated from the treatment unit. Despite the complexity of high-energy neutron dosimetry, the authors succeeded in developing a relatively simple analytical model to predict these exposures. This finding is important because, with further development, it could provide a method to predict stray radiation exposures as an enhanced form of routine treatment planning. Fontenot et al (2010) report on methods to evaluate uncertainties in comparative risk assessments; knowledge of uncertainties is vital to determine the limits of applicability in these assessments, which may in turn affect clinical and policy decisions. Howell et al (2010a) report on the accuracy of a widely used radiation treatment planning system. In particular, they investigated the system's dosimetric accuracy outside the treatment beam, e.g. due to scatter and leakage radiation from external-beam photon therapy. This study provides important illustrative evidence of the need to carefully validate dose algorithms in out-of-field regions. In a related study, Howell et al (2010b) developed a methodology to estimate doses to partially in-field and out-of-field organs. Scarboro et al (2010) report on the impact of organ size and position on out-of-field dose estimates. Taddei et al (2010a) report on the targeting accuracy of a novel device that can be used to treat age-related macular degeneration, the leading cause of blindness in the developed world. Taddei et al (2010b) report on the risks of radiogenic second cancers following proton and photon radiation therapies for liver cancer. Taddei et al (2010c) also compare the risks of radiogenic second cancers from secondary neutrons for a boy and a girl after receiving craniospinal irradiation with passively scattered proton beams. Scanned-beam proton therapy is presently considered the technologically most complex beam delivery approach and is used in only a few centers worldwide. Coutrakon et al (2010) reported on an investigation of dosimetric errors associated with the delivery of scanned proton beams. Titt et al (2010) report on a novel method to adjust the size of scanned proton beams. This study is important because our inability to produce very small beam spot sizes has been an obstacle to realizing the full clinical potential of this technique. Yepes et al (2010) report on the speedup and accuracy of a fast proton dose algorithm that uses an array of graphics processing units; this technique represents a nascent low-cost alternative to the traditional approach of high-performance computing using central processing units. Radiation exposures from kilovoltage computed tomography (CT) procedures have increased dramatically, with the fraction of collective effective dose from CT exposures rising from 3% in the early 1980s to 49% in 2006 (NCRP 2009). Proton CT is an emerging technology that may enable reductions in both proton range uncertainties and the imaging dose to the patient relative to comparable kilovoltage CT techniques. Erdelyi (2010) reports on uncertainties in electron densities estimated using proton CT. Finally, Cheung et al (2010) report on the suitability of advanced composite fiducial markers for localization of the prostate in proton therapy. Their analysis is particularly important because approximately 60% of the proton treatment capacity in the United States is used for patients with prostate cancer. The symposium was the fourth of a series entitled 'Symposia on Computational Cancer Research'. The symposia have alternately been hosted by The University of Texas M D Anderson Cancer Center, Rice University, and Northern Illinois University. The fifth joint symposium will be held in Houston, on 5-7 April 2011, and will focus on survivorship issues after childhood cancers (www.regonline.com/5thjointsymposium). On behalf of the symposium organizing committee, I hope to see you there. Wayne Newhauser, The University of Texas M D Anderson Cancer Center, USA Chairman of 4th Joint Symposium Organizing Committee and Guest Editor References Altekruse S F et al (ed) SEER Cancer Statistics Review, 1975--2007 (Bethesda, MD: National Cancer Institute) (http://seer.cancer.gov/csr/1975_2007/) based on November 2009 SEER data submission, posted to the SEER website, 2010 Cheung J, Kudchadker R J, Zhu X R, Lee A K and Newhauser W D 2010 Dose perturbations and image artifacts caused by carbon-coated ceramic and stainless steel fiducials used in proton therapy for prostate cancer Phys. Med. Biol. 55 7135-47 Coutrakon G, Wang N, Miller D W and Yang Y 2010 Dose error analysis for a scanned proton beam delivery system Phys. Med. Biol. 55 7081-96 Disis M L and Slattery J T 2010 The road we must take: multidisciplinary team science Sci. Transl. Med. 2 22cm9 Doi K 2006 Diagnostic imaging over the last 50 years: research and development in medical imaging science and technology Phys. Med. Biol. 51 R5-27 Durante M and Loeffler J S 2010 Charged particles in radiation oncology Nat. Rev. Clin. Oncol. 7 37-43 Erdelyi B 2010 Electron density uncertainties in proton computed tomography Phys. Med. Biol. 55 7121-34 Fontenot J D, Bloch C, Followill D, Titt U, Zhang M and Newhauser W D 2010 Estimate of the uncertainties in the relative risk of secondary malignant neoplasms following proton therapy and intensity-modulated photon therapy Phys. Med. Biol. 55 6987-98 Friedman D L, Whitton J, Leisenring W, Mertens A C, Hammond S, Stovall M, Donaldson S S, Meadows A T, Robison L L and Neglia J P 2010 Subsequent neoplasms in 5-year survivors of childhood cancer: the Childhood Cancer Survivor Study J. Natl Cancer Inst. 102 1083-95 Geurts van Kessel A 2010 The 'omics' of cancer Cancer Genet. Cytogenet. 203 37-42 Howell R M, Scarboro S B, Kry S F and Yaldo D Z 2010a Accuracy of out-of-field dose calculations by a commercial treatment planning system Phys. Med. Biol. 55 6999-7008 Howell R M, Scarboro S B, Taddei P J, Krishnan S, Kry S F and Newhauser W D 2010b Methodology for determining doses to in-field, out-of-field and partially in-field organs for late effects studies in proton radiotherapy Phys. Med. Biol. 55 7009-23 Hudson M M, Mulrooney D A, Bowers D C, Sklar C A, Green D M, Donaldson S S, Oeffinger K C, Neglia J P, Meadows A T and Robison L L 2009 High-risk populations identified in Childhood Cancer Survivor Study investigations: implications for risk-based surveillance J. Clin. Oncol. 27 2405-14 Jemal A, Siegel R, Ward E, Hao Y, Xu J and Thun M J 2009 Cancer statistics, 2009 CA Cancer J. Clin. 59 225-49 Kalender W A 2006 X-ray computed tomography Phys. Med. Biol. 51 R29-43 Mardis E R 2008 Next-generation DNA sequencing methods Annu. Rev. Genomics Hum. Genet. 9 387-402 Meadows A T, Friedman D L, Neglia J P, Mertens A C, Donaldson S S, Stovall M, Hammond S, Yasui Y and Inskip P D 2009 Second neoplasms in survivors of childhood cancer: findings from the Childhood Cancer Survivor Study cohort J. Clin. Oncol. 27 2356-62 NCRP (National Council on Radiation Protection and Measurements) 2009 Ionizing radiation exposure of the population of the United States {\\it NCRP Report No. 160} (Bethesda, MD: NCRP) Pearson T A and Manolio T A 2008 How to interpret a genome-wide association study JAMA 299 1335-44 Rogers D W 2006 Fifty years of Monte Carlo simulations for medical physics Phys. Med. Biol. 51 R287-301 Sanbonmatsu K Y and Tung C S 2007 High performance computing in biology: multimillion atom simulations of nanoscale systems J. Struct. Biol. 157 470-80 Scarboro S B, Stovall M, White A, Smith S A, Yaldo D, Kry S F and Howell R M 2010 Effect of organ size and position on out-of-field dose distributions during radiation therapy Phys. Med. Biol. 55 7025-36 Spezi E (ed) 2010 Special section: Selected papers from the Second European Workshop on Monte Carlo Treatment Planning (MCTP2009) Phys. Med. Biol. 55 (16) 4431-614 Stovall M, Weathers R, Kasper C, Smith S A, Travis L, Ron E and Kleinerman R 2006 Dose reconstruction for therapeutic and diagnostic radiation exposures: use in epidemiological studies Radiat. Res. 166 141-57 Taddei P J, Chell E, Hansen S, Gertner M and Newhauser W D 2010a Assessment of targeting accuracy of a low-energy stereotactic radiosurgery treatment for age-related macular degeneration Phys. Med. Biol. 55 7037-54 Taddei P J, Howell R M, Krishnan S, Scarboro S B, Mirkovic D and Newhauser W D 2010b Risk of second malignant neoplasm following proton versus intensity-modulated photon radiotherapies for hepatocellular carcinoma Phys. Med. Biol. 55 7055-65 Taddei P J, Mahajan A, Mirkovic D, Zhang R, Giebeler A, Kornguth D, Harvey M, Woo S and Newhauser W D 2010c Predicted risks of second malignant neoplasm incidence and mortality due to secondary neutrons in a girl and boy receiving proton craniospinal irradiation Phys. Med. Biol. 55 7067-80 Titt U, Mirkovic D, Sawakuchi G O, Perles L A, Newhauser W D, Taddei P J and Mohan R 2010 Adjustment of the lateral and longitudinal size of scanned proton beam spots using a pre-absorber to optimize penumbrae and delivery efficiency Phys. Med. Biol. 55 7097-106 Travis L B 2006 The epidemiology of second primary cancers Cancer Epidemiol. Biomarkers Prev. 15 2020-6 Wolkenhauer O et al 2010 Systems biologists seek fuller integration of systems biology approaches in new cancer research programs Cancer Res. 70 12-3 Xu X G, Bednarz B and Paganetti H 2008 A review of dosimetry studies on external-beam radiation treatment with respect to second cancer induction Phys. Med. Biol. 53 R193-241 Yepes P, Mirkovic D and Taddei P J 2010 A GPU implementation of a track-repeating algorithm for proton radiotherapy dose calculations Phys. Med. Biol. 55 7107-20 Zhang R, P\\'{e}rez-And\\'{u}jar A, Fontenot J D, Taddei P J and Newhauser W D 2010 An analytic model of neutron ambient dose equivalent and equivalent dose for proton radiotherapy Phys. Med. Biol. 55 6975-85

MULTI-WAVELENGTH STUDY OF A DELTA-SPOT. I. A REGION OF VERY STRONG, HORIZONTAL MAGNETIC FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaeggli, S. A., E-mail: sarah.jaeggli@nasa.gov

Active region NOAA 11035 appeared in 2009 December, early in the new solar activity cycle. This region achieved a delta sunspot (δ spot) configuration when parasitic flux emerged near the rotationally leading magnetic polarity and traveled through the penumbra of the largest sunspot in the group. Both visible and infrared imaging spectropolarimetry of the magnetically sensitive Fe i line pairs at 6302 and 15650 Å show large Zeeman splitting in the penumbra between the parasitic umbra and the main sunspot umbra. The polarized Stokes spectra in the strongest field region display anomalous profiles, and strong blueshifts are seen in anmore » adjacent region. Analysis of the profiles is carried out using a Milne–Eddington inversion code capable of fitting either a single magnetic component with stray light or two independent magnetic components to verify the field strength. The inversion results show that the anomalous profiles cannot be produced by the combination of two profiles with moderate magnetic fields. The largest field strengths are 3500–3800 G in close proximity to blueshifts as strong as 3.8 km s{sup −1}. The strong, nearly horizontal magnetic field seen near the polarity inversion line in this region is difficult to understand in the context of a standard model of sunspot magnetohydrostatic equilibrium.« less

System for the measurement of ultra-low stray light levels. [determining the adequacy of large space telescope systems

NASA Technical Reports Server (NTRS)

Wyman, C. L.; Griner, D. B.; Hurd, W. A.; Shelton, G. B.; Hunt, G. H.; Fannin, B. B.; Brealt, R. P.; Hawkins, C. A. (Inventor)

1978-01-01

An apparatus is described for measuring the effectiveness of stray light suppression light shields and baffle arrangements used in optical space experiments and large space telescopes. The light shield and baffle arrangement and a telescope model are contained in a vacuum chamber. A source of short, high-powered light energy illuminates portions of the light shield and baffle arrangement and reflects a portion of same to a photomultiplier tube by virtue of multipath scattering. The resulting signal is transferred to time-channel electronics timed by the firing of the high energy light source allowing time discrimination of the signal thereby enabling the light scattered and suppressed by the model to be distinguished from the walls and holders around the apparatus.

A synchrotron study of defect and strain inhomogeneity in laser-assisted three-dimensionally-printed Ni-based superalloy

DOE PAGES

Li, Yao; Qian, Dan; Xue, Jiawei; ...

2015-11-02

Synchrotron X-ray microdiffraction was employed to investigate the inhomogeneous distribution of defect and residual strain in the transitional region between the dendritic and stray grains in a laser-assisted 3D printed Ni-based superalloy. The dendritic region was found to be under tensile strain transversely to the primary dendrite arm directions. The dendrite edges, where high level of strains and geometrically necessary dislocations were detected, were discerned as low angle grain boundaries. Lastly, high angle grain boundaries were observed in the stray grain region, and the orientation of the strain tensor in this region varied dramatically at the micron scale, in contrastmore » with the more or less homogeneous distribution in the dendritic region.« less

Space optics; Proceedings of the Seminar, Huntsville, Ala., May 22-24, 1979

NASA Technical Reports Server (NTRS)

Wyman, C. L.

1979-01-01

The seminar focused on infrared systems, the space telescope, new design for space astronomy, future earth resources systems, and planetary systems. Papers were presented on infrared astronomy satellite, infrared telescope on Spacelab 2, design alternatives for the Shuttle Infrared Telescope Facility, Spacelab 2 infrared telescope cryogenic system, geometrical theory of diffraction and telescope stray-light analysis, Space Telescope scientific instruments, faint-object spectrograph for the Space Telescope, light scattering from multilayer optics, bidirectional reflectance distribution function measurements of stray light suppression coatings for the Space Telescope, optical fabrication of a 60-in. mirror, interferogram analysis for space optics, nuclear-pumped lasers for space application, geophysical fluid flow experiment, coherent rays for optical astronomy in space, optical system with fiber-optical elements, and Pioneer-Venus solar flux radiometer.

Comparative investigation of diagnosis media for induction machine mechanical unbalance fault.

PubMed

Salah, Mohamed; Bacha, Khmais; Chaari, Abdelkader

2013-11-01

For an induction machine, we suggest a theoretical development of the mechanical unbalance effect on the analytical expressions of radial vibration and stator current. Related spectra are described and characteristic defect frequencies are determined. Moreover, the stray flux expressions are developed for both axial and radial sensor coil positions and a substitute diagnosis technique is proposed. In addition, the load torque effect on the detection efficiency of these diagnosis media is discussed and a comparative investigation is performed. The decisive factor of comparison is the fault sensitivity. Experimental results show that spectral analysis of the axial stray flux can be an alternative solution to cover effectiveness limitation of the traditional stator current technique and to substitute the classical vibration practice. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

The use of computed radiography plates to determine light and radiation field coincidence.

PubMed

Kerns, James R; Anand, Aman

2013-11-01

Photo-stimulable phosphor computed radiography (CR) has characteristics that allow the output to be manipulated by both radiation and optical light. The authors have developed a method that uses these characteristics to carry out radiation field and light field coincidence quality assurance on linear accelerators. CR detectors from Kodak were used outside their cassettes to measure both radiation and light field edges from a Varian linear accelerator. The CR detector was first exposed to a radiation field and then to a slightly smaller light field. The light impinged on the detector's latent image, removing to an extent the portion exposed to the light field. The detector was then digitally scanned. A MATLAB-based algorithm was developed to automatically analyze the images and determine the edges of the light and radiation fields, the vector between the field centers, and the crosshair center. Radiographic film was also used as a control to confirm the radiation field size. Analysis showed a high degree of repeatability with the proposed method. Results between the proposed method and radiographic film showed excellent agreement of the radiation field. The effect of varying monitor units and light exposure time was tested and found to be very small. Radiation and light field sizes were determined with an uncertainty of less than 1 mm, and light and crosshair centers were determined within 0.1 mm. A new method was developed to digitally determine the radiation and light field size using CR photo-stimulable phosphor plates. The method is quick and reproducible, allowing for the streamlined and robust assessment of light and radiation field coincidence, with no observer interpretation needed.

Impact of a 3-year pet management program on pet population and owner's perception.

PubMed

Dias Costa, Esther; Martins, Camila Marinelli; Cunha, Graziela Ribeiro; Catapan, Dariane Cristina; Ferreira, Fernando; Oliveira, Simone Tostes; Garcia, Rita de Cassia Maria; Biondo, Alexander Welker

2017-04-01

Although pet population management programs have been established worldwide, few reports on program evaluation have been carried out to date. Accordingly, a 3-year longitudinal study has been carried out in a 4000 household neighborhood located within the metropolitan area of Curitiba, the eighth most populated city of Brazil. Visits were conducted and questionnaires completed to estimate and characterize the local pet population (animal sex, reproductive and vaccination status, street access). Care provided by owners, community perception on stray dog management and the possible changes were compared in these variables over time (2010 and 2013) were evaluated, after the establishment of a city pet population management program. In addition, associations between having children, owning dogs and cats, responsible pet ownership education and owner's perception on stray dogs were statistically tested. A total of 354/4000 (8.9%) household families were interviewed in 2010 and 70/354 (19.8%) of the same families again in 2013. No significant changes were found in overall number of dogs and cats and average pet age, animal care and owner's perception on stray dogs following the 3-year population management program. In 2010, an average of 1.6 dogs and 0.3 cats were found per family, with slightly more females (51.3% dogs and 51.1% cats), adults (4.0±3.5years for dogs and 2.1±2.4 for cats), intact (not neutered; 94.2% dogs and 84.0% cats) and lacking regular visit to veterinarian (71.6%). Although more families (53.1%) had children under 12 years old, no association was found between having children and having dogs and cats. Questionnaires revealed that owners perceived neutering/spaying to be the best pet population control method (42.4%), with "society" (50%) and "government" (49.4%) as responsible for pet population management. A significant positive association has been found between education level and the best way to control stray dogs (p=0.03), between having dogs and in favor of neutering/spaying (p=0.04) and considering neutering/spaying as the best control method (p=0.02). The chances of thinking the best way to control stray dogs by neutering/spaying and adoption were almost 2.0 fold higher than other methods. In conclusion, the present study has provided indicators (education level, having dogs) for pet population control program assessment and effectiveness evaluation. Moreover, this study may serve as a warning on the real long-term effect of such programs, which should be periodically evaluated to identify necessary adjustments and/or improvements. Copyright © 2017 Elsevier B.V. All rights reserved.

Light-Cone Effect of Radiation Fields in Cosmological Radiative Transfer Simulations

NASA Astrophysics Data System (ADS)

Ahn, Kyungjin

2015-02-01

We present a novel method to implement time-delayed propagation of radiation fields in cosmo-logical radiative transfer simulations. Time-delayed propagation of radiation fields requires construction of retarded-time fields by tracking the location and lifetime of radiation sources along the corresponding light-cones. Cosmological radiative transfer simulations have, until now, ignored this "light-cone effect" or implemented ray-tracing methods that are computationally demanding. We show that radiative trans-fer calculation of the time-delayed fields can be easily achieved in numerical simulations when periodic boundary conditions are used, by calculating the time-discretized retarded-time Green's function using the Fast Fourier Transform (FFT) method and convolving it with the source distribution. We also present a direct application of this method to the long-range radiation field of Lyman-Werner band photons, which is important in the high-redshift astrophysics with first stars.

Simulation and modeling of silicon pore optics for the ATHENA x-ray telescope

NASA Astrophysics Data System (ADS)

Spiga, D.; Christensen, F. E.; Bavdaz, M.; Civitani, M. M.; Conconi, P.; Della Monica Ferreira, D.; Knudsen, E. B.; Massahi, S.; Pareschi, G.; Salmaso, B.; Shortt, B.; Tayabaly, K.; Westergaard, N. J.; Wille, E.

2016-07-01

The ATHENA X-ray observatory is a large-class ESA approved mission, with launch scheduled in 2028. The technology of silicon pore optics (SPO) was selected as baseline to assemble ATHENA's optic with more than 1000 mirror modules, obtained by stacking wedged and ribbed silicon wafer plates onto silicon mandrels to form the Wolter-I configuration. Even if the current baseline design fulfills the required effective area of 2 m2 at 1 keV on-axis, alternative design solutions, e.g., privileging the field of view or the off-axis angular resolution, are also possible. Moreover, the stringent requirement of a 5 arcsec HEW angular resolution at 1 keV entails very small profile errors and excellent surface smoothness, as well as a precise alignment of the 1000 mirror modules to avoid imaging degradation and effective area loss. Finally, the stray light issue has to be kept under control. In this paper we show the preliminary results of simulations of optical systems based on SPO for the ATHENA X-ray telescope, from pore to telescope level, carried out at INAF/OAB and DTU Space under ESA contract. We show ray-tracing results, including assessment of the misalignments of mirror modules and the impact of stray light. We also deal with a detailed description of diffractive effects expected in an SPO module from UV light, where the aperture diffraction prevails, to X-rays where the surface diffraction plays a major role. Finally, we analyze the results of X-ray tests performed at the BESSY synchrotron, we compare them with surface finishing measurements, and we estimate the expected HEW degradation caused by the X-ray scattering.

Grass height and transmission ecology of Echinococcus multilocularis in Tibetan communities, China.

PubMed

Wang, Qian; Raoul, Francis; Budke, Christine; Craig, Philip S; Xiao, Yong-fu; Vuitton, Dominique A; Campos-Ponce, Maiza; Qiu, Dong-chuan; Pleydell, David; Giraudoux, Patrick

2010-01-05

Alveolar echinococcosis is a major zoonosis of public health significance in western China. Overgrazing was recently assumed as a potential risk factor for transmission of alveolar echinococcosis. The research was designed to further test the overgrazing hypothesis by investigating how overgrazing influenced the burrow density of intermediate host small mammals and how the burrow density of small mammals was associated with dog Echinococcus multilocularis infection. The study sites were chosen by previous studies which found areas where the alveolar echinococcosis was prevalent. The data, including grass height, burrow density of intermediate host small mammals, dog and fox fecal samples as well as Global Positioning System (GPS) position, were collected from field investigations in Shiqu County, Sichuan Province, China. The fecal samples were analyzed using copro-PCR. The worms, teeth, bones and hairs in the fecal samples were visually examined. Single factor and multifactor analyses tools including chi square and generalized linear models were applied to these data. By using grass height as a proxy of grazing pressure in the homogenous pasture, this study found that taller grass in the pasture led to lower small mammals' burrow density (chi(2) = 4.670, P = 0.031, coefficient = -1.570). The Echinococcus multilocularis worm burden in dogs was statistically significantly related to the maximum density of the intermediate host Ochotona spp. (chi(2) = 5.250, P = 0.022, coefficient = 0.028). The prevalence in owned dogs was positively correlated to the number of stray dogs seen within a 200 meter radius (Wald chi(2) = 8.375, P = 0.004, odds ratio = 1.198). Our findings support the hypothesis that overgrazing promotes transmission of alveolar echinococcosis and confirm the role of stray dogs in the transmission of alveolar echinococcosis.

Concurrence of aqueous and gas phase contamination of groundwater in the Wattenberg oil and gas field of northern Colorado.

PubMed

Li, Huishu; Son, Ji-Hee; Carlson, Kenneth H

2016-01-01

The potential impact of rapid development of unconventional oil and natural gas resources using hydraulic fracturing and horizontal drilling on regional groundwater quality has received significant attention. Major concerns are methane or oil/gas related hydrocarbon (such as TPHs, BTEX including benzene, toluene, ethybenzene and xylene) leaks into the aquifer due to the failure of casing and/or stray gas migration. Previously, we investigated the relationship between oil and gas activity and dissolved methane concentration in a drinking water aquifer with the major finding being the presence of thermogenic methane contamination, but did not find detectable concentrations of TPHs or BTEX. To understand if aqueous and gas phases from the producing formation were transported concurrently to drinking water aquifers without the presence of oil/gas related hydrocarbons, the ionic composition of three water groups was studied: (1) uncontaminated deep confined aquifer, (2) suspected contaminated groundwater - deep confined aquifer containing thermogenic methane, and (3) produced water from nearby oil and gas wells that would represent aqueous phase contaminants. On the basis of quantitative and spatial analysis, we identified that the "thermogenic methane contaminated" groundwater did not have similarities to produced water in terms of ionic character (e.g. Cl/TDS ratio), but rather to the "uncontaminated" groundwater. The analysis indicates that aquifer wells with demonstrated gas phase contamination have not been contacted by an aqueous phase from oil and gas operations according to the methodology we use in this study and the current groundwater quality data from COGCC. However, the research does not prove conclusively that this the case. The results may provide insight on contamination mechanisms since improperly sealed well casing may result in stray gas but not aqueous phase transport. Copyright © 2015 Elsevier Ltd. All rights reserved.

Landsat 9: Status and Plans

NASA Technical Reports Server (NTRS)

Markham, Brian L.; Jenstrom, Del; Masek, Jeffrey G.; Dabney, Phil; Pedelty, Jeffrey A.; Barsi, Julia A.; Montanaro, Matthew

2016-01-01

The Landsat 9 mission, currently under development and proceeding towards a targeted launch in late 2020, will be very similar to the Landsat 8 mission, launched in 2013. Like Landsat 8, Landsat 9 is a joint effort between NASA and USGS with two sensors, the Operational Land Imager 2 (OLI-2), essentially a copy of the OLI on Landsat 8 and the Thermal Infrared Sensor 2 (TIRS-2), very similar to the TIRS on Landsat 8. The OLI-2, like OLI, provides 14-bit image data, though for Landsat 9, all 14 bits will be retained and transmitted to the ground. The focal plane modules to be used for OLI-2 were flight spares for OLI and are currently being retested by Ball Aerospace. Results indicate radiometric performance comparable to OLI. The TIRS was a class C instrument, with a 3-year design lifetime, and therefore had limited redundancy. TIRS-2 will be a class B instrument, with a 5-year design lifetime, like OLI (and OLI-2), necessitating design changes to increase redundancy. The stray light and Scene Select Mechanism (SSM) encoder problems observed on orbit with TIRS have also instigated a few design changes to TIRS-2. Stray light analysis and testing have indicated that additional baffles in the TIRS-2 optical system will suppress the out-of-field response. The SSM encoder problems have not been definitively traced to a route cause, though conductive anodic filament growth in the circuit boards is suspected. Improved designs for the encoder are being considered for TIRS-2. The spare Focal Plane Array (FPA) from TIRS is planned for use in TIRS-2; FPA spectral and radiometric performance testing is scheduled for September of this year at NASA's Goddard Space Flight Center.

Development of diagnostic and manipulation systems for space-charge dominated electron beams and confined electron plasmas in ELTRAP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rome, M.; Cavaliere, F.; Maero, G.

2013-03-19

Modifications have been implemented in the Penning-Malmberg device ELTRAP aimed at performing studies on the dynamics of space-charge dominated nanosecond electron bunches traveling along the magnetic field. In particular, a Thomson backscattering apparatus has been developed where an infrared (IR) laser pulse collides with the bunched electron beam. The frequency-shifted backscattered radiation, acquired by means of a photomultiplier (PMT), can be exploited to evaluate information on energy, energy spread and density of the bunch. The achievable sensitivity of the diagnostics has been estimated, and valuable information on the main parameters affecting the signal-to-noise (S/N) ratio has been obtained [B. Paroli,more » F. Cavaliere, M. Cavenago, F. De Luca, M. Ikram, G. Maero, C. Marini, R. Pozzoli, and M. Rome, JINST 7, P01008 (2012)]. A series of upgrades are under way, aimed at increasing the S/N ratio through the use of a new laser for the electron source, the insertion of a stray light shield, and the optimization of the detection electronics. Moreover, electromagnetic simulations relevant to the design and implementation of a microwave heating system are presented. The generation of an electron plasma in ELTRAP by means of a low-power radio frequency (RF) drive in the MHz range applied on one of the trap electrodes and under ultra-high vacuum (UHV) conditions has previously been demonstrated [B. Paroli, F. De Luca, G. Maero, F. Pozzoli, and M. Rome, Plasma Sources Sci. Technol. 19, 045013 (2010)]. The new heating system will allow the extension of the RF studies to the GHz range and in particular the production of a more energetic electron plasma via cyclotron resonant excitation.« less

On the use of a novel Ferrous Xylenol-orange gelatin dosimeter for HDR brachytherapy commissioning and quality assurance testing.

PubMed

Pappas, Eleftherios P; Peppa, Vasiliki; Hourdakis, Costas J; Karaiskos, Pantelis; Papagiannis, Panagiotis

2018-01-01

To evaluate a commercially available Ferrous-Xylenol Orange-Gel (FXG) dosimeter (TrueView™) coupled with Optical-Computed Tomography (OCT) read out, for 3D dose verification in an Ir-192 superficial brachytherapy application. Two identical polyethylene containers filled with gel from the same batch were used. One was irradiated with an 18 MeV electron field to examine the dose-response linearity and obtain a calibration curve. A flap surface applicator was attached to the other to simulate treatment of a skin lesion. The dose distribution in the experimental set up was calculated with the TG-43 and the model based dose calculation (MBCA) algorithms of a commercial treatment planning system (TPS), as well as Monte Carlo (MC) simulation using the MCNP code. Measured and calculated dose distributions were spatially registered and compared. Apart from a region close to the container's neck, where gel measurements exhibited an over-response relative to MC calculations (probably due to stray light perturbation), an excellent agreement was observed between measurements and simulations. More than 97% of points within the 10% isodose line (80 cGy) met the gamma index criteria established from uncertainty analysis (5%/2 mm). The corresponding passing rates for the comparison of experiment to calculations using the TG-43 and MBDCA options of the TPS were 57% and 92%, respectively. TrueView™ is suitable for the quality assurance of demanding radiotherapy applications. Experimental results of this work confirm the advantage of the studied MBDCA over TG-43, expected from the improved account of scatter radiation in the treatment geometry. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

30 CFR 57.6605 - Isolation of blasting circuits.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Extraneous Electricity-Surface and Underground § 57.6605 Isolation of blasting circuits. Lead wires and... shall be protected from sources of stray or static electricity. Blasting circuits shall be protected...

30 CFR 57.6605 - Isolation of blasting circuits.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Extraneous Electricity-Surface and Underground § 57.6605 Isolation of blasting circuits. Lead wires and... shall be protected from sources of stray or static electricity. Blasting circuits shall be protected...

30 CFR 57.6605 - Isolation of blasting circuits.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Extraneous Electricity-Surface and Underground § 57.6605 Isolation of blasting circuits. Lead wires and... shall be protected from sources of stray or static electricity. Blasting circuits shall be protected...

30 CFR 57.6605 - Isolation of blasting circuits.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Extraneous Electricity-Surface and Underground § 57.6605 Isolation of blasting circuits. Lead wires and... shall be protected from sources of stray or static electricity. Blasting circuits shall be protected...