Mid-frequency MTF compensation of optical sparse aperture system.

PubMed

Zhou, Chenghao; Wang, Zhile

2018-03-19

Optical sparse aperture (OSA) can greatly improve the spatial resolution of optical system. However, because of its aperture dispersion and sparse, its mid-frequency modulation transfer function (MTF) are significantly lower than that of a single aperture system. The main focus of this paper is on the mid-frequency MTF compensation of the optical sparse aperture system. Firstly, the principle of the mid-frequency MTF decreasing and missing of optical sparse aperture are analyzed. This paper takes the filling factor as a clue. The method of processing the mid-frequency MTF decreasing with large filling factor and method of compensation mid-frequency MTF with small filling factor are given respectively. For the MTF mid-frequency decreasing, the image spatial-variant restoration method is proposed to restore the mid-frequency information in the image; for the mid-frequency MTF missing, two images obtained by two system respectively are fused to compensate the mid-frequency information in optical sparse aperture image. The feasibility of the two method are analyzed in this paper. The numerical simulation of the system and algorithm of the two cases are presented using Zemax and Matlab. The results demonstrate that by these two methods the mid-frequency MTF of OSA system can be compensated effectively.

Image quality analysis of a color LCD as well as a monochrome LCD using a Foveon color CMOS camera

NASA Astrophysics Data System (ADS)

Dallas, William J.; Roehrig, Hans; Krupinski, Elizabeth A.

2007-09-01

We have combined a CMOS color camera with special software to compose a multi-functional image-quality analysis instrument. It functions as a colorimeter as well as measuring modulation transfer functions (MTF) and noise power spectra (NPS). It is presently being expanded to examine fixed-pattern noise and temporal noise. The CMOS camera has 9 μm square pixels and a pixel matrix of 2268 x 1512 x 3. The camera uses a sensor that has co-located pixels for all three primary colors. We have imaged sections of both a color and a monochrome LCD monitor onto the camera sensor with LCD-pixel-size to camera-pixel-size ratios of both 12:1 and 17.6:1. When used as an imaging colorimeter, each camera pixel is calibrated to provide CIE color coordinates and tristimulus values. This capability permits the camera to simultaneously determine chromaticity in different locations on the LCD display. After the color calibration with a CS-200 colorimeter the color coordinates of the display's primaries determined from the camera's luminance response are very close to those found from the CS-200. Only the color coordinates of the display's white point were in error. For calculating the MTF a vertical or horizontal line is displayed on the monitor. The captured image is color-matrix preprocessed, Fourier transformed then post-processed. For NPS, a uniform image is displayed on the monitor. Again, the image is pre-processed, transformed and processed. Our measurements show that the horizontal MTF's of both displays have a larger negative slope than that of the vertical MTF's. This behavior indicates that the horizontal MTF's are poorer than the vertical MTF's. However the modulations at the Nyquist frequency seem lower for the color LCD than for the monochrome LCD. The spatial noise of the color display in both directions is larger than that of the monochrome display. Attempts were also made to analyze the total noise in terms of spatial and temporal noise by applying subtractions of images taken at exactly the same exposure. Temporal noise seems to be significantly lower than spatial noise.

MTF measurement and analysis of linear array HgCdTe infrared detectors

NASA Astrophysics Data System (ADS)

Zhang, Tong; Lin, Chun; Chen, Honglei; Sun, Changhong; Lin, Jiamu; Wang, Xi

2018-01-01

The slanted-edge technique is the main method for measurement detectors MTF, however this method is commonly used on planar array detectors. In this paper the authors present a modified slanted-edge method to measure the MTF of linear array HgCdTe detectors. Crosstalk is one of the major factors that degrade the MTF value of such an infrared detector. This paper presents an ion implantation guard-ring structure which was designed to effectively absorb photo-carriers that may laterally defuse between adjacent pixels thereby suppressing crosstalk. Measurement and analysis of the MTF of the linear array detectors with and without a guard-ring were carried out. The experimental results indicated that the ion implantation guard-ring structure effectively suppresses crosstalk and increases MTF value.

Lunar-edge based on-orbit modulation transfer function (MTF) measurement

NASA Astrophysics Data System (ADS)

Cheng, Ying; Yi, Hongwei; Liu, Xinlong

2017-10-01

Modulation transfer function (MTF) is an important parameter for image quality evaluation of on-orbit optical image systems. Various methods have been proposed to determine the MTF of an imaging system which are based on images containing point, pulse and edge features. In this paper, the edge of the moon can be used as a high contrast target to measure on-orbit MTF of image systems based on knife-edge methods. The proposed method is an extension of the ISO 12233 Slanted-edge Spatial Frequency Response test, except that the shape of the edge is a circular arc instead of a straight line. In order to get more accurate edge locations and then obtain a more authentic edge spread function (ESF), we choose circular fitting method based on least square to fit lunar edge in sub-pixel edge detection process. At last, simulation results show that the MTF value at Nyquist frequency calculated using our lunar edge method is reliable and accurate with error less than 2% comparing with theoretical MTF value.

Optical analysis of electro-optical systems by MTF calculus

NASA Astrophysics Data System (ADS)

Barbarini, Elisa Signoreto; Dos Santos, Daniel, Jr.; Stefani, Mário Antonio; Yasuoka, Fátima Maria Mitsue; Castro Neto, Jarbas C.; Rodrigues, Evandro Luís Linhari

2011-08-01

One of the widely used methods for performance analysis of an optical system is the determination of the Modulation Transfer Function (MTF). The MTF represents a quantitative and direct measure of image quality, and, besides being an objective test, it can be used on concatenated optical system. This paper presents the application of software called SMTF (software modulation transfer function), built in C++ and Open CV platforms for MTF calculation on electro-optical system. Through this technique, it is possible to develop specific method to measure the real time performance of a digital fundus camera, an infrared sensor and an ophthalmological surgery microscope. Each optical instrument mentioned has a particular device to measure the MTF response, which is being developed. Then the MTF information assists the analysis of the optical system alignment, and also defines its resolution limit by the MTF graphic. The result obtained from the implemented software is compared with the theoretical MTF curve from the analyzed systems.

Directional MTF measurement using sphere phantoms for a digital breast tomosynthesis system

NASA Astrophysics Data System (ADS)

Lee, Changwoo; Baek, Jongduk

2015-03-01

The digital breast tomosynthesis (DBT) has been widely used as a diagnosis imaging modality of breast cancer because of potential for structure noise reduction, better detectability, and less breast compression. Since 3D modulation transfer function (MTF) is one of the quantitative metrics to assess the spatial resolution of medical imaging systems, it is very important to measure 3D MTF of the DBT system to evaluate the resolution performance. In order to do that, Samei et al. used sphere phantoms and applied Thornton's method to the DBT system. However, due to the limitation of Thornton's method, the low frequency drop, caused by the limited data acquisition angle and reconstruction filters, was not measured correctly. To overcome this limitation, we propose a Richardson-Lucy (RL) deconvolution based estimation method to measure the directional MTF. We reconstructed point and sphere objects using FDK algorithm within a 40⁰ data acquisition angle. The ideal 3D MTF is obtained by taking Fourier transform of the reconstructed point object, and three directions (i.e., fx-direction, fy-direction, and fxy-direction) of the ideal 3D MTF are used as a reference. To estimate the directional MTF, the plane integrals of the reconstructed and ideal sphere object were calculated and used to estimate the directional PSF using RL deconvolution technique. Finally, the directional MTF was calculated by taking Fourier transform of the estimated PSF. Compared to the previous method, the proposed method showed a good agreement with the ideal directional MTF, especially at low frequency regions.

Development of Pseudorandom Binary Arrays for Calibration of Surface Profile Metrology Tools

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

Barber, S.K.; Takacs, P.; Soldate, P.

2009-12-01

Optical metrology tools, especially for short wavelengths (extreme ultraviolet and x-ray), must cover a wide range of spatial frequencies from the very low, which affects figure, to the important mid-spatial frequencies and the high spatial frequency range, which produces undesirable scattering. A major difficulty in using surface profilometers arises due to the unknown point-spread function (PSF) of the instruments [G. D. Boreman, Modulation Transfer Function in Optical and Electro-Optical Systems (SPIE, Bellingham, WA, 2001)] that is responsible for distortion of the measured surface profile. Generally, the distortion due to the PSF is difficult to account for because the PSF ismore » a complex function that comes to the measurement via the convolution operation, while the measured profile is described with a real function. Accounting for instrumental PSF becomes significantly simpler if the result of measurement of a profile is presented in the spatial frequency domain as a power spectral density (PSD) distribution [J. W. Goodman, Introduction to Fourier Optics, 3rd ed. (Roberts and Company, Englewood, CO, 2005)]. For example, measured PSD distributions provide a closed set of data necessary for three-dimensional calculations of scattering of light by the optical surfaces [E. L. Church et al., Opt. Eng. (Bellingham) 18, 125 (1979); J. C. Stover, Optical Scattering, 2nd ed. (SPIE Optical Engineering Press, Bellingham, WA, 1995)]. The distortion of the surface PSD distribution due to the PSF can be modeled with the modulation transfer function (MTF), which is defined over the spatial frequency bandwidth of the instrument. The measured PSD distribution can be presented as a product of the squared MTF and the ideal PSD distribution inherent for the system under test. Therefore, the instrumental MTF can be evaluated by comparing a measured PSD distribution of a known test surface with the corresponding ideal numerically simulated PSD. The square root of the ratio of the measured and simulated PSD distributions gives the MTF of the instrument. The applicability of the MTF concept to phase map measurements with optical interferometric microscopes needs to be experimentally verified as the optical tool and algorithms may introduce nonlinear artifacts into the process. In previous work [V. V. Yashchuk et al., Proc. SPIE 6704, 670408 (2007); Valeriy V. Yashchuk et al., Opt. Eng. (Bellingham) 47, 073602 (2008)] the instrumental MTF of a surface profiler was precisely measured using reference test surfaces based on binary pseudorandom (BPR) gratings. Here, the authors present results of fabricating and using two-dimensional (2D) BPR arrays that allow for a direct 2D calibration of the instrumental MTF. BPR sequences are widely used in engineering and communication applications such as global position systems and wireless communication protocols. The ideal BPR pattern has a flat 'white noise' response over the entire range of spatial frequencies of interest. The BPR array used here is based on the uniformly redundant array (URA) prescription [E. E. Fenimore and T. M. Cannon, Appl. Opt. 17, 337 (1978)] initially used for x-ray and gamma ray astronomy applications. The URA's superior imaging capability originates from the fact that its cyclical autocorrelation function very closely approximates a delta function, which produces a flat PSD. Three different size BPR array patterns were fabricated by electron beam lithography and induction coupled plasma etching of silicon. The basic size units were 200, 400, and 600 nm. Two different etch processes were used, CF{sub 4}/Ar and HBr, which resulted in undercut and vertical sidewall profiles, respectively. The 2D BPR arrays were used as standard test surfaces for MTF calibration of the MicroMap{trademark}-570 interferometric microscope using all available objectives. The MicroMap{trademark}-570 interferometric microscope uses incoherent illumination from a tungsten filament source and common path modulated phase shifting interference to produce a set of interferograms detected on a change coupled device. Mathematical algorithms applied to the datasets yield the surface phase map. The HBr etched two-dimensional BPR arrays have proven to be a very effective calibration standard making possible direct calibration corrections without the need of additional calculation considerations, while departures from the ideal vertical sidewall require an additional correction term for the CF{sub 4}/Ar etched samples [Samuel K. Barber et al., Abstract to Optics and Photonics 2009: Optical Engineering and Applications Symposium, San Diego, CA, 2-6 August 2009]. Initial surface roughness of low cost 'prime' wafers limits low magnification calibration but should not be a limitation if better polished samples are used.« less

MTF measurements on real time for performance analysis of electro-optical systems

NASA Astrophysics Data System (ADS)

Stuchi, Jose Augusto; Signoreto Barbarini, Elisa; Vieira, Flavio Pascoal; dos Santos, Daniel, Jr.; Stefani, Mário Antonio; Yasuoka, Fatima Maria Mitsue; Castro Neto, Jarbas C.; Linhari Rodrigues, Evandro Luis

2012-06-01

The need of methods and tools that assist in determining the performance of optical systems is actually increasing. One of the most used methods to perform analysis of optical systems is to measure the Modulation Transfer Function (MTF). The MTF represents a direct and quantitative verification of the image quality. This paper presents the implementation of the software, in order to calculate the MTF of electro-optical systems. The software was used for calculating the MTF of Digital Fundus Camera, Thermal Imager and Ophthalmologic Surgery Microscope. The MTF information aids the analysis of alignment and measurement of optical quality, and also defines the limit resolution of optical systems. The results obtained with the Fundus Camera and Thermal Imager was compared with the theoretical values. For the Microscope, the results were compared with MTF measured of Microscope Zeiss model, which is the quality standard of ophthalmological microscope.

Dynamic MTF measurement

NASA Astrophysics Data System (ADS)

Bardoux, Alain; Gimenez, Thierry; Jamin, Nicolas; Seve, Frederic

2017-11-01

MTF (Modulation Transfer Frequency) of a detector is a key parameter for imagers. When image is not moving on the detector, MTF can be measured by some methods (knife edge, slanted slit,…). But with LEO satellites, image is moving on the surface of the detector, and MTF has to be measured in the same way: that is what we call "dynamic MTF". CNES (French Space Agency) has built a specific bench in order to measure dynamic MTF of detectors (CCD and CMOS), especially with component working in TDI (Time delay and integration) mode. The method is based on a moving edge, synchronized with the movement of charges inside the TDI detector. The moving part is a rotating cube, allowing a very stable movement of the image on the surface of the detector The main difficulties were: - stability of the rotating speed - synchronization between cube speed and charge transfer inside the detectors - synchronization between cube position and data acquisition. Different methods have been tested for the displacement of the knife edge: - geometrical displacement - electrical shift of the charge transfer clocks. Static MTF has been performed before dynamic measurements, in order to fix a reference measurement, Then dynamic MTF bench has been set up. The results, for a TDI CCD show a very good precision. So this bench is validated, and the dynamic MTF value of the TDI CCD is confirmed.

Technical Note: Comparison of first- and second-generation photon-counting slit-scanning tomosynthesis systems.

PubMed

Berggren, Karl; Cederström, Björn; Lundqvist, Mats; Fredenberg, Erik

2018-02-01

Digital breast tomosynthesis (DBT) is an emerging tool for breast-cancer screening and diagnostics. The purpose of this study is to present a second-generation photon-counting slit-scanning DBT system and compare it to the first-generation system in terms of geometry and image quality. The study presents the first image-quality measurements on the second-generation system. The geometry of the new system is based on a combined rotational and linear motion, in contrast to a purely rotational scan motion in the first generation. In addition, the calibration routines have been updated. Image quality was measured in the center of the image field in terms of in-slice modulation transfer function (MTF), artifact spread function (ASF), and in-slice detective quantum efficiency (DQE). Images were acquired using a W/Al 29 kVp spectrum at 13 mAs with 2 mm Al additional filtration and reconstructed using simple back-projection. The in-slice 50% MTF was improved in the chest-mammilla direction, going from 3.2 to 3.5 lp/mm, and the zero-frequency DQE increased from 0.71 to 0.77. The MTF and ASF were otherwise found to be on par for the two systems. The new system has reduced in-slice variation of the tomographic angle. The new geometry is less curved, which reduces in-slice tomographic-angle variation, and increases the maximum compression height, making the system accessible for a larger population. The improvements in MTF and DQE were attributed to the updated calibration procedures. We conclude that the second-generation system maintains the key features of the photon-counting system while maintaining or improving image quality and improving the maximum compression height. © 2017 American Association of Physicists in Medicine.

A method to measure the presampling MTF in digital radiography using Wiener deconvolution

NASA Astrophysics Data System (ADS)

Zhou, Zhongxing; Zhu, Qingzhen; Gao, Feng; Zhao, Huijuan; Zhang, Lixin; Li, Guohui

2013-03-01

We developed a novel method for determining the presampling modulation transfer function (MTF) of digital radiography systems from slanted edge images based on Wiener deconvolution. The degraded supersampled edge spread function (ESF) was obtained from simulated slanted edge images with known MTF in the presence of poisson noise, and its corresponding ideal ESF without degration was constructed according to its central edge position. To meet the requirements of the absolute integrable condition of Fourier transformation, the origianl ESFs were mirrored to construct the symmetric pattern of ESFs. Then based on Wiener deconvolution technique, the supersampled line spread function (LSF) could be acquired from the symmetric pattern of degraded supersampled ESFs in the presence of ideal symmetric ESFs and system noise. The MTF is then the normalized magnitude of the Fourier transform of the LSF. The determined MTF showed a strong agreement with the theoritical true MTF when appropriated Wiener parameter was chosen. The effects of Wiener parameter value and the width of square-like wave peak in symmetric ESFs were illustrated and discussed. In conclusion, an accurate and simple method to measure the presampling MTF was established using Wiener deconvolution technique according to slanted edge images.

MTF measurement of LCDs by a linear CCD imager: I. Monochrome case

NASA Astrophysics Data System (ADS)

Kim, Tae-hee; Choe, O. S.; Lee, Yun Woo; Cho, Hyun-Mo; Lee, In Won

1997-11-01

We construct the modulation transfer function (MTF) measurement system of a LCD using a linear charge-coupled device (CCD) imager. The MTF used in optical system can not describe in the effect of both resolution and contrast on the image quality of display. Thus we present the new measurement method based on the transmission property of a LCD. While controlling contrast and brightness levels, the MTF is measured. From the result, we show that the method is useful for describing of the image quality. A ne measurement method and its condition are described. To demonstrate validity, the method is applied for comparison of the performance of two different LCDs.

Optimization of x-ray capillary optics for mammography

NASA Astrophysics Data System (ADS)

Ross, Richard E.; Bradford, Carla D.; Peppler, Walter W.

2002-05-01

The purpose of this study is to develop a full-field digital mammography system utilizing capillary optics. Specific aims are to identify optic properties that affect image quality and to optimize those properties in the design of a multi-element capillary array. It has been shown that polycapillary optics significantly improve mammographic image quality through increased resolution and reduced x-ray scatter. For practical clinical application much larger multi-element optics will be required. This study quantified the contributing factors to the multi-element optic MTF and investigated methods to determine optimal parameters for a practical design. Individual and a prototype multi-element array of linearly tapered optics with a common focal point were investigated. A conventional (MO/MO) mammography tube and computed radiography system were used. The system and optic MTF were measured using the angled slit method with a slit camera (10 micron slit). MTF measurements were performed with both stationary and scanned optics. Contributions to MTF included: distortion within individual optics, misalignment between optics, capillary channel size, and vibration. Measurement techniques used to identify and quantify the contributions to optic MTF included a phantom chosen specifically for polycapillary optics. This phantom provided a method for assessing the coherence among capillaries within an optic as well as the relative alignment of the optics within the array. In addition, modifications to the scanning procedure allowed for the isolation and quantification of several contributors to the system MTF. Specifically, measurements were made using a stationary optic, a scanning optic, and an optic placed at multiple locations within the imaged field of view. These techniques yielded the optic MTF, the degradation of MTF due to loss of coherence within the optic, and the degradation of MTF due to vibration of the scanning mechanism. Distortion within individual optics was, typically, quite small. However, MTF degradation resulting from twist was significant in some optics. MTF degradation due to misalignment was relatively large in the prototype triad. Modeling found that misalignment up to 50 microns reduced MTF by less than 10 percent up to 3 cycles/mm. Channel diameters of 52 microns and 85 microns reduced MTF by 9 percent to 20 percent at 5 cycles/mm and provided an optimal tradeoff between transmission and MTF. Vibration was identified as a significant degradation to MTF but can easily reduced with simple modifications. In spite of some reduced optic MTF values, system MTF has always been significantly improved - in some cases almost by the magnification ratio. These results allow for accurate modeling of optic performance and optimization of design parameters. This study demonstrates that a multi-element array can be produced with nearly optimal properties. A large area array suitable for clinical trial is feasible and is the next step in this program.

Pipeline for effective denoising of digital mammography and digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Borges, Lucas R.; Bakic, Predrag R.; Foi, Alessandro; Maidment, Andrew D. A.; Vieira, Marcelo A. C.

2017-03-01

Denoising can be used as a tool to enhance image quality and enforce low radiation doses in X-ray medical imaging. The effectiveness of denoising techniques relies on the validity of the underlying noise model. In full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT), calibration steps like the detector offset and flat-fielding can affect some assumptions made by most denoising techniques. Furthermore, quantum noise found in X-ray images is signal-dependent and can only be treated by specific filters. In this work we propose a pipeline for FFDM and DBT image denoising that considers the calibration steps and simplifies the modeling of the noise statistics through variance-stabilizing transformations (VST). The performance of a state-of-the-art denoising method was tested with and without the proposed pipeline. To evaluate the method, objective metrics such as the normalized root mean square error (N-RMSE), noise power spectrum, modulation transfer function (MTF) and the frequency signal-to-noise ratio (SNR) were analyzed. Preliminary tests show that the pipeline improves denoising. When the pipeline is not used, bright pixels of the denoised image are under-filtered and dark pixels are over-smoothed due to the assumption of a signal-independent Gaussian model. The pipeline improved denoising up to 20% in terms of spatial N-RMSE and up to 15% in terms of frequency SNR. Besides improving the denoising, the pipeline does not increase signal smoothing significantly, as shown by the MTF. Thus, the proposed pipeline can be used with state-of-the-art denoising techniques to improve the quality of DBT and FFDM images.

[Accuracy of Modulation Transfer Function for Target Size and Field of View in a Circular Edge Strategy Using the CT Image Measurement Program].

PubMed

Fukunaga, Masaaki; Onishi, Hideo; Matsutomo, Norikazu; Yamamoto, Hiroyuki

2016-06-01

The purpose of this study was to evaluate the effects of target diameter and display-field of view (D-FOV) in modulation transfer function (MTF) by circular edge strategy using the computed tomography (CT) image measurement program "CTmeasure". We calculated the MTF (MTF(edge)) using the circular edge strategy applied to cylindrical phantom (200 mmφ) that inserted with cylinders have 10, 20, 30, and 40 mm diameters. The phantom images were reconstructed using filtered back projection method varied with D-FOV (240, 320, 400, and 500 mm). The study compared both MTF(edge) and MTF(wire) at MTF50% and MTF(10%) for target diameter and D-FOV, respectively. The MTF(edge) by the different of target diameter indicated in rough compatibility. However, MTF(edge) of D-FOV diameters (320, 400, and 500 mm) decreased in the high frequency range. The circular edge strategy for MTF depended on the D-FOV, however, it was little dependent on target diameter using the CT image measurement program "CTmeasure".

Modulation Transfer Function (MTF) measurement techniques for lenses and linear detector arrays

NASA Technical Reports Server (NTRS)

Schnabel, J. J., Jr.; Kaishoven, J. E., Jr.; Tom, D.

1984-01-01

Application is the determination of the Modulation Transfer Function (MTF) for linear detector arrays. A system set up requires knowledge of the MTF of the imaging lens. Procedure for this measurement is described for standard optical lab equipment. Given this information, various possible approaches to MTF measurement for linear arrays is described. The knife edge method is then described in detail.

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

Yashchuk, V.V.; Conley, R.; Anderson, E.H.

Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binarypseudo-random (BPR) gratings and arrays has been suggested and and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer. Here we describe the details of development of binarypseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electronmore » microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi{sub 2}/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML testsamples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.« less

MTF measurements of a type-II superlattice infrared focal plane array sealed in a cryocooler.

PubMed

Nghiem, Jean; Jaeck, Julien; Primot, Jerome; Coudrain, Christophe; Derelle, Sophie; Huard, Edouard; Caes, Marcel; Bernhardt, Sylvie; Haidar, Riad; Christol, Philippe; Ribet-Mohamed, Isabelle

2018-04-16

In operational electro-optical systems, infrared focal plane arrays (IR FPA) are integrated in cryocoolers which induce vibrations that may strongly affect their modulation transfer function (MTF). In this paper, we present the MTF measurement of an IR FPA sealed in its cryocooler. The method we use to measure the MTF decorrelates operational constraints and the technological limitations of the IR FPA. The bench is based on the diffraction properties of a continuously self imaging grating (CSIG). The 26 µm pixel size extracted from the MTF measurement is in good agreement with the expected value.

Intravaginal administration of metformin hydrochloride loaded cationic niosomes amalgamated with thermosensitive gel for the treatment of polycystic ovary syndrome: In vitro and in vivo studies.

PubMed

Saini, Neetu; Sodhi, Rupinder Kaur; Bajaj, Lotika; Pandey, Ravi Shankar; Jain, Upendra Kumar; Katare, Om Prakash; Madan, Jitender

2016-08-01

Metformin hydrochloride (MTF-HCl) is extensively recommended by physicians for the treatment of polycystic ovary syndrome (PCOS). Mechanistically, MTF-HCl activates AMP-dependent kinase-α (AMPK-α) pathway to decrease the glucose production, enhances fatty acid oxidation and elevates the uptake of glucose in tissues. However, despite favourable physicochemical properties, oral administration of MTF-HCl is associated with impaired bioavailability (50-60%), lactic-acidosis and frequent dosing (500mg 2-3 times a day) in PCOS that ultimately influence the patient compliance. Therefore, in present investigation, MTF-HCl loaded unmodified and cationic small unilamellar niosomes were separately amalgamated with thermosensitive gel (MTF-HCl-SUNs-Gel and MTF-HCl-C-SUNs-Gel) for the treatment of PCOS through vaginal route of administration. MTF-HCl-SUNs and MTF-HCl-C-SUNs were separately prepared by reverse phase evaporation method. The nanovesicle size and zeta-potential of MTF-HCl-C-SUNs were measured to be 210.3±14.8-nm (P<0.05) and +8.7±2.7-mV (P<0.001), significantly higher than 198.5±20.3-nm and -16.6±3.9-mV of MTF-HCl-SUNs, respectively. Moreover, promising results of in vitro characterization parameters like gelation time, gelling temperature, viscosity analysis, percent mucoadhesiveness and drug release of MTF-HCl-C-SUNs-Gel and MTF-HCl-SUNs-Gel ensured the candidature of tailored gels for further in vivo investigations. In this way, treatment of PCOS rats under scheduled dose-dosage regimen with oral MTF-HCl solution, intravaginal MTF-HCl-SUNs-Gel and intravaginal MTF-HCl-C-SUNs-gel exhibited remarkable alterations, recruitment and development of normal follicles in addition to normalization of level of various hormones in PCOS. In conclusion, MTF-C-SUNs-Gel has paved the way for developing intravaginal dosage form of MTF-HCl for the treatment of PCOS. Copyright © 2016 Elsevier B.V. All rights reserved.

Addressing challenges of modulation transfer function measurement with fisheye lens cameras

NASA Astrophysics Data System (ADS)

Deegan, Brian M.; Denny, Patrick E.; Zlokolica, Vladimir; Dever, Barry; Russell, Laura

2015-03-01

Modulation transfer function (MTF) is a well defined and accepted method of measuring image sharpness. The slanted edge test, as defined in ISO12233 is a standard method of calculating MTF, and is widely used for lens alignment and auto-focus algorithm verification. However, there are a number of challenges which should be considered when measuring MTF in cameras with fisheye lenses. Due to trade-offs related Petzval curvature, planarity of the optical plane is difficult to achieve in fisheye lenses. It is therefore critical to have the ability to accurately measure sharpness throughout the entire image, particularly for lens alignment. One challenge for fisheye lenses is that, because of the radial distortion, the slanted edges will have different angles, depending on the location within the image and on the distortion profile of the lens. Previous work in the literature indicates that MTF measurements are robust for angles between 2 and 10 degrees. Outside of this range, MTF measurements become unreliable. Also, the slanted edge itself will be curved by the lens distortion, causing further measurement problems. This study summarises the difficulties in the use of MTF for sharpness measurement in fisheye lens cameras, and proposes mitigations and alternative methods.

Multi-frame linear regressive filter for the measurement of infrared pixel spatial response and MTF from sparse data.

PubMed

Huard, Edouard; Derelle, Sophie; Jaeck, Julien; Nghiem, Jean; Haïdar, Riad; Primot, Jérôme

2018-03-05

A challenging point in the prediction of the image quality of infrared imaging systems is the evaluation of the detector modulation transfer function (MTF). In this paper, we present a linear method to get a 2D continuous MTF from sparse spectral data. Within the method, an object with a predictable sparse spatial spectrum is imaged by the focal plane array. The sparse data is then treated to return the 2D continuous MTF with the hypothesis that all the pixels have an identical spatial response. The linearity of the treatment is a key point to estimate directly the error bars of the resulting detector MTF. The test bench will be presented along with measurement tests on a 25 μm pitch InGaAs detector.

An optimized knife-edge method for on-orbit MTF estimation of optical sensors using powell parameter fitting

NASA Astrophysics Data System (ADS)

Han, Lu; Gao, Kun; Gong, Chen; Zhu, Zhenyu; Guo, Yue

2017-08-01

On-orbit Modulation Transfer Function (MTF) is an important indicator to evaluate the performance of the optical remote sensors in a satellite. There are many methods to estimate MTF, such as pinhole method, slit method and so on. Among them, knife-edge method is quite efficient, easy-to-use and recommended in ISO12233 standard for the wholefrequency MTF curve acquisition. However, the accuracy of the algorithm is affected by Edge Spread Function (ESF) fitting accuracy significantly, which limits the range of application. So in this paper, an optimized knife-edge method using Powell algorithm is proposed to improve the ESF fitting precision. Fermi function model is the most popular ESF fitting model, yet it is vulnerable to the initial values of the parameters. Considering the characteristics of simple and fast convergence, Powell algorithm is applied to fit the accurate parameters adaptively with the insensitivity to the initial parameters. Numerical simulation results reveal the accuracy and robustness of the optimized algorithm under different SNR, edge direction and leaning angles conditions. Experimental results using images of the camera in ZY-3 satellite show that this method is more accurate than the standard knife-edge method of ISO12233 in MTF estimation.

Modified slanted-edge method for camera modulation transfer function measurement using nonuniform fast Fourier transform technique

NASA Astrophysics Data System (ADS)

Duan, Yaxuan; Xu, Songbo; Yuan, Suochao; Chen, Yongquan; Li, Hongguang; Da, Zhengshang; Gao, Limin

2018-01-01

ISO 12233 slanted-edge method experiences errors using fast Fourier transform (FFT) in the camera modulation transfer function (MTF) measurement due to tilt angle errors in the knife-edge resulting in nonuniform sampling of the edge spread function (ESF). In order to resolve this problem, a modified slanted-edge method using nonuniform fast Fourier transform (NUFFT) for camera MTF measurement is proposed. Theoretical simulations for images with noise at a different nonuniform sampling rate of ESF are performed using the proposed modified slanted-edge method. It is shown that the proposed method successfully eliminates the error due to the nonuniform sampling of the ESF. An experimental setup for camera MTF measurement is established to verify the accuracy of the proposed method. The experiment results show that under different nonuniform sampling rates of ESF, the proposed modified slanted-edge method has improved accuracy for the camera MTF measurement compared to the ISO 12233 slanted-edge method.

Generic Sensor Modeling Using Pulse Method

NASA Technical Reports Server (NTRS)

Helder, Dennis L.; Choi, Taeyoung

2005-01-01

Recent development of high spatial resolution satellites such as IKONOS, Quickbird and Orbview enable observation of the Earth's surface with sub-meter resolution. Compared to the 30 meter resolution of Landsat 5 TM, the amount of information in the output image was dramatically increased. In this era of high spatial resolution, the estimation of spatial quality of images is gaining attention. Historically, the Modulation Transfer Function (MTF) concept has been used to estimate an imaging system's spatial quality. Sometimes classified by target shapes, various methods were developed in laboratory environment utilizing sinusoidal inputs, periodic bar patterns and narrow slits. On-orbit sensor MTF estimation was performed on 30-meter GSD Landsat4 Thematic Mapper (TM) data from the bridge pulse target as a pulse input . Because of a high resolution sensor s small Ground Sampling Distance (GSD), reasonably sized man-made edge, pulse, and impulse targets can be deployed on a uniform grassy area with accurate control of ground targets using tarps and convex mirrors. All the previous work cited calculated MTF without testing the MTF estimator's performance. In previous report, a numerical generic sensor model had been developed to simulate and improve the performance of on-orbit MTF estimating techniques. Results from the previous sensor modeling report that have been incorporated into standard MTF estimation work include Fermi edge detection and the newly developed 4th order modified Savitzky-Golay (MSG) interpolation technique. Noise sensitivity had been studied by performing simulations on known noise sources and a sensor model. Extensive investigation was done to characterize multi-resolution ground noise. Finally, angle simulation was tested by using synthetic pulse targets with angles from 2 to 15 degrees, several brightness levels, and different noise levels from both ground targets and imaging system. As a continuing research activity using the developed sensor model, this report was dedicated to MTF estimation via pulse input method characterization using the Fermi edge detection and 4th order MSG interpolation method. The relationship between pulse width and MTF value at Nyquist was studied including error detection and correction schemes. Pulse target angle sensitivity was studied by using synthetic targets angled from 2 to 12 degrees. In this report, from the ground and system noise simulation, a minimum SNR value was suggested for a stable MTF value at Nyquist for the pulse method. Target width error detection and adjustment technique based on a smooth transition of MTF profile is presented, which is specifically applicable only to the pulse method with 3 pixel wide targets.

Characterization of photon-counting multislit breast tomosynthesis.

PubMed

Berggren, Karl; Cederström, Björn; Lundqvist, Mats; Fredenberg, Erik

2018-02-01

It has been shown that breast tomosynthesis may improve sensitivity and specificity compared to two-dimensional mammography, resulting in increased detection-rate of cancers or lowered call-back rates. The purpose of this study is to characterize a spectral photon-counting multislit breast tomosynthesis system that is able to do single-scan spectral imaging with multiple collimated x-ray beams. The system differs in many aspects compared to conventional tomosynthesis using energy-integrating flat-panel detectors. The investigated system was a prototype consisting of a dual-threshold photon-counting detector with 21 collimated line detectors scanning across the compressed breast. A review of the system is done in terms of detector, acquisition geometry, and reconstruction methods. Three reconstruction methods were used, simple back-projection, filtered back-projection and an iterative algebraic reconstruction technique. The image quality was evaluated by measuring the modulation transfer-function (MTF), normalized noise-power spectrum, detective quantum-efficiency (DQE), and artifact spread-function (ASF) on reconstructed spectral tomosynthesis images for a total-energy bin (defined by a low-energy threshold calibrated to remove electronic noise) and for a high-energy bin (with a threshold calibrated to split the spectrum in roughly equal parts). Acquisition was performed using a 29 kVp W/Al x-ray spectrum at a 0.24 mGy exposure. The difference in MTF between the two energy bins was negligible, that is, there was no energy dependence on resolution. The MTF dropped to 50% at 1.5 lp/mm to 2.3 lp/mm in the scan direction and 2.4 lp/mm to 3.3 lp/mm in the slit direction, depending on the reconstruction method. The full width at half maximum of the ASF was found to range from 13.8 mm to 18.0 mm for the different reconstruction methods. The zero-frequency DQE of the system was found to be 0.72. The fraction of counts in the high-energy bin was measured to be 59% of the total detected spectrum. Scantimes ranged from 4 s to 16.5 s depending on voltage and current settings. The characterized system generates spectral tomosynthesis images with a dual-energy photon-counting detector. Measurements show a high DQE, enabling high image quality at a low dose, which is beneficial for low-dose applications such as screening. The single-scan spectral images open up for applications such as quantitative material decomposition and contrast-enhanced tomosynthesis. © 2017 American Association of Physicists in Medicine.

[Study of Image Quality Comparison Based on the MTF Method Between Different Medical Rigid Endoscopes in an In Vitro Model].

PubMed

Wang, Yunlong; Ji, Jun; Jiang, Changsong; Huang, Zengyue

2015-04-01

This study was aimed to use the method of modulation transfer function (MTF) to compare image quality among three different Olympus medical rigid cystoscopes in an in vitro model. During the experimental processes, we firstly used three different types of cystoscopes (i. e. OLYMPUS cystourethroscopy with FOV of 12 degrees, OLYMPUS Germany A22003A and OLYMPUS A2013A) to collect raster images at different brightness with industrial camera and computer from the resolution target which is with different spatial frequency, and then we processed the collected images using MALAB software with the optical transfer function MTF to obtain the values of MTF at different brightness and different spatial frequency. We then did data mathematical statistics and compared imaging quality. The statistical data showed that all three MTF values were smaller than 1. MTF values with the spatial frequency gradually increasing would decrease approaching 0 at the same brightness. When the brightness enhanced in the same process at the same spatial frequency, MTF values showed a slowly increasing trend. The three endoscopes' MTF values were completely different. In some cases the MTF values had a large difference, and the maximum difference could reach 0.7. Conclusion can be derived from analysis of experimental data that three Olympus medical rigid cystoscopes have completely different imaging quality abilities. The No. 3 endoscope OLYMPUS A2013A has low resolution but high contrast. The No. 1 endoscope OLYMPUS cystourethroscopy with FOV of 12 degrees, on the contrary, had high resolution and lower contrast. The No. 2 endoscope OLYMPUS Germany A22003A had high contrast and high resolution, and its image quality was the best.

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

V Yashchuk; R Conley; E Anderson

Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1] and [2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanningmore » (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.« less

Resolution Properties Of A Computed Radiographic System

NASA Astrophysics Data System (ADS)

Fujita, Hiroshi; Morishita, Junji; Ueda, Katsuhiko; Tsai, Du Y.; Ohtsuka, Akiyoshi; Fujikawa, Tsuyoshi

1989-05-01

The analysis of spatial-resolution properties in terms of the modulation transfer function (MTF) has been presented in a computed radiographic (CR) system (FCR-101) with the photostimulable-phosphor plate (imaging plate, IP). The newly devised method of determining the presampling MTF which includes the x-ray detector (IP) unsharpness and the unsharpness of the sampling aperture is described in which an image of a slightly-angulated lead slit relative to a horizontal or vertical direction is employed. The IP MTFs as an analog MTF in the system, the presampling MTFs for different types of IPs, different sampling distances, different versions of IPs, simultaneous multisection tomography and magnification radiography, and the laser-printer MTFs as display MTF are measured and shown. The effective sampling aperture MTFs calculated indicate that the noticeable degradation of resolution occurs at the stage of image data sampling. The usefulness of the magnification technique for mammography and bone radiography is demonstrated. It is shown that both of the digital MTF and the overall MTF are difficult to use for general purpose due to the aliasing artifacts. The effect of glare on the contrast is also characterized by lead-disk method. The glare fraction is found to be approximately 6.5%.

GOCI image enhancement using an MTF compensation technique for coastal water applications.

PubMed

Oh, Eunsong; Choi, Jong-Kuk

2014-11-03

The Geostationary Ocean Color Imager (GOCI) is the first optical sensor in geostationary orbit for monitoring the ocean environment around the Korean Peninsula. This paper discusses on-orbit modulation transfer function (MTF) estimation with the pulse-source method and its compensation results for the GOCI. Additionally, by analyzing the relationship between the MTF compensation effect and the accuracy of the secondary ocean product, we confirmed the optimal MTF compensation parameter for enhancing image quality without variation in the accuracy. In this study, MTF assessment was performed using a natural target because the GOCI system has a spatial resolution of 500 m. For MTF compensation with the Wiener filter, we fitted a point spread function with a Gaussian curve controlled by a standard deviation value (σ). After a parametric analysis for finding the optimal degradation model, the σ value of 0.4 was determined to be an optimal indicator. Finally, the MTF value was enhanced from 0.1645 to 0.2152 without degradation of the accuracy of the ocean color product. Enhanced GOCI images by MTF compensation are expected to recognize small-scale ocean products in coastal areas with sharpened geometric performance.

Contrast computation methods for interferometric measurement of sensor modulation transfer function

NASA Astrophysics Data System (ADS)

Battula, Tharun; Georgiev, Todor; Gille, Jennifer; Goma, Sergio

2018-01-01

Accurate measurement of image-sensor frequency response over a wide range of spatial frequencies is very important for analyzing pixel array characteristics, such as modulation transfer function (MTF), crosstalk, and active pixel shape. Such analysis is especially significant in computational photography for the purposes of deconvolution, multi-image superresolution, and improved light-field capture. We use a lensless interferometric setup that produces high-quality fringes for measuring MTF over a wide range of frequencies (here, 37 to 434 line pairs per mm). We discuss the theoretical framework, involving Michelson and Fourier contrast measurement of the MTF, addressing phase alignment problems using a moiré pattern. We solidify the definition of Fourier contrast mathematically and compare it to Michelson contrast. Our interferometric measurement method shows high detail in the MTF, especially at high frequencies (above Nyquist frequency). We are able to estimate active pixel size and pixel pitch from measurements. We compare both simulation and experimental MTF results to a lens-free slanted-edge implementation using commercial software.

MTF analysis of LANDSAT-4 Thematic Mapper

NASA Technical Reports Server (NTRS)

Schowengerdt, R.

1983-01-01

The spatial radiance distribution of a ground target must be known to a resolution at least four to five times greater than that of the system under test when measuring a satellite sensor's modulation transfer function. Calibration of the target requires either the use of man-made special purpose targets with known properties, e.g., a small reflective mirror or a dark-light linear pattern such as line or edge, or use of relatively high resolution underflight imagery to calibrate an arbitrary ground scene. Both approaches are to be used in addition a technique that utilizes an analytical model for the scene spatial frequency power spectrum is being investigated as an alternative to calibration of the scene.

MTF Analysis of LANDSAT-4 Thematic Mapper

NASA Technical Reports Server (NTRS)

Schowengerdt, R.

1985-01-01

The spatial radiance distribution of a ground target must be known to a resolution at least four to five times greater than that of the system under test when measuring a satellite sensor's modulation transfer function. Calibration of the target requires either the use of man-made special purpose targets with known properties, e.g., a small reflective mirror or a dark-light linear pattern such as line or edge, or use of relatively high resolution underflight imagery to calibrate an arbitrary ground scene. Both approaches are to be used, in addition a technique that utilizes an analytical model of the scene spatial frequency power spectrum is being investigated as an alternative to calibration of the scene.

Reference-free determination of tissue absorption coefficient by modulation transfer function characterization in spatial frequency domain.

PubMed

Chen, Weiting; Zhao, Huijuan; Li, Tongxin; Yan, Panpan; Zhao, Kuanxin; Qi, Caixia; Gao, Feng

2017-08-08

Spatial frequency domain (SFD) measurement allows rapid and non-contact wide-field imaging of the tissue optical properties, thus has become a potential tool for assessing physiological parameters and therapeutic responses during photodynamic therapy of skin diseases. The conventional SFD measurement requires a reference measurement within the same experimental scenario as that for a test one to calibrate mismatch between the real measurements and the model predictions. Due to the individual physical and geometrical differences among different tissues, organs and patients, an ideal reference measurement might be unavailable in clinical trials. To address this problem, we present a reference-free SFD determination of absorption coefficient that is based on the modulation transfer function (MTF) characterization. Instead of the absolute amplitude that is used in the conventional SFD approaches, we herein employ the MTF to characterize the propagation of the modulated lights in tissues. With such a dimensionless relative quantity, the measurements can be naturally corresponded to the model predictions without calibrating the illumination intensity. By constructing a three-dimensional database that portrays the MTF as a function of the optical properties (both the absorption coefficient μ a and the reduced scattering coefficient [Formula: see text]) and the spatial frequency, a look-up table approach or a least-square curve-fitting method is readily applied to recover the absorption coefficient from a single frequency or multiple frequencies, respectively. Simulation studies have verified the feasibility of the proposed reference-free method and evaluated its accuracy in the absorption recovery. Experimental validations have been performed on homogeneous tissue-mimicking phantoms with μ a ranging from 0.01 to 0.07 mm -1 and [Formula: see text] = 1.0 or 2.0 mm -1 . The results have shown maximum errors of 4.86 and 7% for [Formula: see text] = 1.0 mm -1 and [Formula: see text] = 2.0 mm -1 , respectively. We have also presented quantitative ex vivo imaging of human lung cancer in a subcutaneous xenograft mouse model for further validation, and observed high absorption contrast in the tumor region. The proposed method can be applied to the rapid and accurate determination of the absorption coefficient, and better yet, in a reference-free way. We believe this reference-free strategy will facilitate the clinical translation of the SFD measurement to achieve enhanced intraoperative hemodynamic monitoring and personalized treatment planning in photodynamic therapy.

Separation of presampling and postsampling modulation transfer functions in infrared sensor systems

NASA Astrophysics Data System (ADS)

Espinola, Richard L.; Olson, Jeffrey T.; O'Shea, Patrick D.; Hodgkin, Van A.; Jacobs, Eddie L.

2006-05-01

New methods of measuring the modulation transfer function (MTF) of electro-optical sensor systems are investigated. These methods are designed to allow the separation and extraction of presampling and postsampling components from the total system MTF. The presampling MTF includes all the effects prior to the sampling stage of the imaging process, such as optical blur and detector shape. The postsampling MTF includes all the effects after sampling, such as interpolation filters and display characteristics. Simulation and laboratory measurements are used to assess the utility of these techniques. Knowledge of these components and inclusion into sensor models, such as the U.S. Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate's NVThermIP, will allow more accurate modeling and complete characterization of sensor performance.

A hyperspectral image optimizing method based on sub-pixel MTF analysis

NASA Astrophysics Data System (ADS)

Wang, Yun; Li, Kai; Wang, Jinqiang; Zhu, Yajie

2015-04-01

Hyperspectral imaging is used to collect tens or hundreds of images continuously divided across electromagnetic spectrum so that the details under different wavelengths could be represented. A popular hyperspectral imaging methods uses a tunable optical band-pass filter settled in front of the focal plane to acquire images of different wavelengths. In order to alleviate the influence of chromatic aberration in some segments in a hyperspectral series, in this paper, a hyperspectral optimizing method uses sub-pixel MTF to evaluate image blurring quality was provided. This method acquired the edge feature in the target window by means of the line spread function (LSF) to calculate the reliable position of the edge feature, then the evaluation grid in each line was interpolated by the real pixel value based on its relative position to the optimal edge and the sub-pixel MTF was used to analyze the image in frequency domain, by which MTF calculation dimension was increased. The sub-pixel MTF evaluation was reliable, since no image rotation and pixel value estimation was needed, and no artificial information was introduced. With theoretical analysis, the method proposed in this paper is reliable and efficient when evaluation the common images with edges of small tilt angle in real scene. It also provided a direction for the following hyperspectral image blurring evaluation and the real-time focal plane adjustment in real time in related imaging system.

Theory of lidar method for measurement of the modulation transfer function of water layers.

PubMed

Dolin, Lev S

2013-01-10

We develop a method to evaluate the modulation transfer function (MTF) of a water layer from the characteristics of lidar signal backscattered by water volume. We propose several designs of a lidar system for remote measurement of the MTF and the procedure to determine optical properties of water using the measured MTF. We discuss a laser system for sea-bottom imaging that accounts for the influence of water slab on the image structure and allows for correction of image distortions caused by light scattering in water. © 2013 Optical Society of America

Modulation transfer function of a fish-eye lens based on the sixth-order wave aberration theory.

PubMed

Jia, Han; Lu, Lijun; Cao, Yiqing

2018-01-10

A calculation program of the modulation transfer function (MTF) of a fish-eye lens is developed with the autocorrelation method, in which the sixth-order wave aberration theory of ultra-wide-angle optical systems is used to simulate the wave aberration distribution at the exit pupil of the optical systems. The autocorrelation integral is processed with the Gauss-Legendre integral, and the magnification chromatic aberration is discussed to calculate polychromatic MTF. The MTF calculation results of a given example are then compared with those previously obtained based on the fourth-order wave aberration theory of plane-symmetrical optical systems and with those from the Zemax program. The study shows that MTF based on the sixth-order wave aberration theory has satisfactory calculation accuracy even for a fish-eye lens with a large acceptance aperture. And the impacts of different types of aberrations on the MTF of a fish-eye lens are analyzed. Finally, we apply the self-adaptive and normalized real-coded genetic algorithm and the MTF developed in the paper to optimize the Nikon F/2.8 fish-eye lens; consequently, the optimized system shows better MTF performances than those of the original design.

Proceedings of the 2004 High Spatial Resolution Commercial Imagery Workshop

NASA Technical Reports Server (NTRS)

2006-01-01

Topics covered include: NASA Applied Sciences Program; USGS Land Remote Sensing: Overview; QuickBird System Status and Product Overview; ORBIMAGE Overview; IKONOS 2004 Calibration and Validation Status; OrbView-3 Spatial Characterization; On-Orbit Modulation Transfer Function (MTF) Measurement of QuickBird; Spatial Resolution Characterization for QuickBird Image Products 2003-2004 Season; Image Quality Evaluation of QuickBird Super Resolution and Revisit of IKONOS: Civil and Commercial Application Project (CCAP); On-Orbit System MTF Measurement; QuickBird Post Launch Geopositional Characterization Update; OrbView-3 Geometric Calibration and Geopositional Accuracy; Geopositional Statistical Methods; QuickBird and OrbView-3 Geopositional Accuracy Assessment; Initial On-Orbit Spatial Resolution Characterization of OrbView-3 Panchromatic Images; Laboratory Measurement of Bidirectional Reflectance of Radiometric Tarps; Stennis Space Center Verification and Validation Capabilities; Joint Agency Commercial Imagery Evaluation (JACIE) Team; Adjacency Effects in High Resolution Imagery; Effect of Pulse Width vs. GSD on MTF Estimation; Camera and Sensor Calibration at the USGS; QuickBird Geometric Verification; Comparison of MODTRAN to Heritage-based Results in Vicarious Calibration at University of Arizona; Using Remotely Sensed Imagery to Determine Impervious Surface in Sioux Falls, South Dakota; Estimating Sub-Pixel Proportions of Sagebrush with a Regression Tree; How Do YOU Use the National Land Cover Dataset?; The National Map Hazards Data Distribution System; Recording a Troubled World; What Does This-Have to Do with This?; When Can a Picture Save a Thousand Homes?; InSAR Studies of Alaska Volcanoes; Earth Observing-1 (EO-1) Data Products; Improving Access to the USGS Aerial Film Collections: High Resolution Scanners; Improving Access to the USGS Aerial Film Collections: Phoenix Digitizing System Product Distribution; System and Product Characterization: Issues Approach; Innovative Approaches to Analysis of Lidar Data for the National Map; Changes in Imperviousness near Military Installations; Geopositional Accuracy Evaluations of QuickBird and OrbView-3: Civil and Commercial Applications Project (CCAP); Geometric Accuracy Assessment: OrbView ORTHO Products; QuickBird Radiometric Calibration Update; OrbView-3 Radiometric Calibration; QuickBird Radiometric Characterization; NASA Radiometric Characterization; Establishing and Verifying the Traceability of Remote-Sensing Measurements to International Standards; QuickBird Applications; Airport Mapping and Perpetual Monitoring Using IKONOS; OrbView-3 Relative Accuracy Results and Impacts on Exploitation and Accuracy Improvement; Using Remotely Sensed Imagery to Determine Impervious Surface in Sioux Falls, South Dakota; Applying High-Resolution Satellite Imagery and Remotely Sensed Data to Local Government Applications: Sioux Falls, South Dakota; Automatic Co-Registration of QuickBird Data for Change Detection Applications; Developing Coastal Surface Roughness Maps Using ASTER and QuickBird Data Sources; Automated, Near-Real Time Cloud and Cloud Shadow Detection in High Resolution VNIR Imagery; Science Applications of High Resolution Imagery at the USGS EROS Data Center; Draft Plan for Characterizing Commercial Data Products in Support of Earth Science Research; Atmospheric Correction Prototype Algorithm for High Spatial Resolution Multispectral Earth Observing Imaging Systems; Determining Regional Arctic Tundra Carbon Exchange: A Bottom-Up Approach; Using IKONOS Imagery to Assess Impervious Surface Area, Riparian Buffers and Stream Health in the Mid-Atlantic Region; Commercial Remote Sensing Space Policy Civil Implementation Update; USGS Commercial Remote Sensing Data Contracts (CRSDC); and Commercial Remote Sensing Space Policy (CRSSP): Civil Near-Term Requirements Collection Update.

SU-E-I-17: Comparison of Two Novel Algorithms for the Modulation Transfer Function of CT Using a Simple Cylindrical Phantom

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

Kam, S; Youn, H; Kim, H

2014-06-01

Purpose: To compare and analyze two novel algorithms for the assessment of modulation transfer functions (MTFs) of computed tomography (CT) systems using a simple acrylic cylindrical phantom Method and Materials: Images of the acrylic cylindrical phantom were acquired by a GE LightSpeed 16 RT (GE Healthcare, Milwaukee, WI) using 120 kVp, 330 mA, 2.5 mm slice thickness, 10 cm field-of view (FOV), four reconstruction kernels (e.g. standard, soft, detail, bone, and lung). Two different algorithms were used to analyze images for MTF assessment. First, Richard et al. suggested a task-based MTF assessment method through an edge spread function (ESF) whichmore » described pixel intensities as a function of distance from the center. The MTF was obtained as the absolute value of Fourier transform of the differentiated ESF. Second, Ohkubo et al. devised an effective method to determine the point spread function (PSF) of CT system accompanied with verification. The line spread function (LSF), which was the one-dimensional integration of the PSF, was used to obtain the MTF. We validated the reliability of two above-mentioned methods through the comparison with a conventional method using a thin tungsten wire phantom. Results: The measured MTFs by two methods were mostly similar each other for standard, soft, and detail kernels. In 0.6 lp/mm, the MTF difference between two methods were 0.012(standard), 0.004(soft), and 0.037(detail). They also coincided with the MTF by the conventional method well. However, there were considerable distinctions for bone and lung kernels containing edge enhancement that might cause undershoots near the peak of the LSF. Conclusions: We compared two novel methods to assess task-based MTFs for clinical CT systems especially using a simple acrylic cylindrical phantom with high-convenience and low-cost, and validated them against a conventional method. This work can provide a practical solution to users for the quality assurance of CT.« less

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

Yashchuk, Valeriy V; Conley, Raymond; Anderson, Erik H

Verification of the reliability of metrology data from high quality x-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [Proc. SPIE 7077-7 (2007), Opt. Eng. 47(7), 073602-1-5 (2008)} and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [Nucl. Instr. and Meth. A 616, 172-82 (2010)]. Here we describe the details ofmore » development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize x-ray microscopes. Corresponding work with x-ray microscopes is in progress.« less

Estimation of the two-dimensional presampled modulation transfer function of digital radiography devices using one-dimensional test objects

PubMed Central

Wells, Jered R.; Dobbins, James T.

2012-01-01

Purpose: The modulation transfer function (MTF) of medical imaging devices is commonly reported in the form of orthogonal one-dimensional (1D) measurements made near the vertical and horizontal axes with a slit or edge test device. A more complete description is found by measuring the two-dimensional (2D) MTF. Some 2D test devices have been proposed, but there are some issues associated with their use: (1) they are not generally available; (2) they may require many images; (3) the results may have diminished accuracy; and (4) their implementation may be particularly cumbersome. This current work proposes the application of commonly available 1D test devices for practical and accurate estimation of the 2D presampled MTF of digital imaging systems. Methods: Theory was developed and applied to ensure adequate fine sampling of the system line spread function for 1D test devices at orientations other than approximately vertical and horizontal. Methods were also derived and tested for slit nonuniformity correction at arbitrary angle. Techniques were validated with experimental measurements at ten angles using an edge test object and three angles using a slit test device on an indirect-detection flat-panel system [GE Revolution XQ/i (GE Healthcare, Waukesha, WI)]. The 2D MTF was estimated through a simple surface fit with interpolation based on Delaunay triangulation of the 1D edge-based MTF measurements. Validation by synthesis was also performed with simulated images from a hypothetical direct-detection flat-panel device. Results: The 2D MTF derived from physical measurements yielded an average relative precision error of 0.26% for frequencies below the cutoff (2.5 mm−1) and approximate circular symmetry at frequencies below 4 mm−1. While slit analysis generally agreed with the results of edge analysis, the two showed subtle differences at frequencies above 4 mm−1. Slit measurement near 45° revealed radial asymmetry in the MTF resulting from the square pixel aperture (0.2 mm × 0.2 mm), a characteristic which was not necessarily appreciated with the orthogonal 1D MTF measurements. In simulation experiments, both slit- and edge-based measurements resolved the radial asymmetries in the 2D MTF. The average absolute relative accuracy error in the 2D MTF between the DC and cutoff (2.5 mm−1) frequencies was 0.13% with average relative precision error of 0.11%. Other simulation results were similar to those derived from physical data. Conclusions: Overall, the general availability, acceptance, accuracy, and ease of implementation of 1D test devices for MTF assessment make this a valuable technique for 2D MTF estimation. PMID:23039654

Estimation of the two-dimensional presampled modulation transfer function of digital radiography devices using one-dimensional test objects

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

Wells, Jered R.; Dobbins, James T. III; Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705

2012-10-15

Purpose: The modulation transfer function (MTF) of medical imaging devices is commonly reported in the form of orthogonal one-dimensional (1D) measurements made near the vertical and horizontal axes with a slit or edge test device. A more complete description is found by measuring the two-dimensional (2D) MTF. Some 2D test devices have been proposed, but there are some issues associated with their use: (1) they are not generally available; (2) they may require many images; (3) the results may have diminished accuracy; and (4) their implementation may be particularly cumbersome. This current work proposes the application of commonly available 1Dmore » test devices for practical and accurate estimation of the 2D presampled MTF of digital imaging systems. Methods: Theory was developed and applied to ensure adequate fine sampling of the system line spread function for 1D test devices at orientations other than approximately vertical and horizontal. Methods were also derived and tested for slit nonuniformity correction at arbitrary angle. Techniques were validated with experimental measurements at ten angles using an edge test object and three angles using a slit test device on an indirect-detection flat-panel system [GE Revolution XQ/i (GE Healthcare, Waukesha, WI)]. The 2D MTF was estimated through a simple surface fit with interpolation based on Delaunay triangulation of the 1D edge-based MTF measurements. Validation by synthesis was also performed with simulated images from a hypothetical direct-detection flat-panel device. Results: The 2D MTF derived from physical measurements yielded an average relative precision error of 0.26% for frequencies below the cutoff (2.5 mm{sup -1}) and approximate circular symmetry at frequencies below 4 mm{sup -1}. While slit analysis generally agreed with the results of edge analysis, the two showed subtle differences at frequencies above 4 mm{sup -1}. Slit measurement near 45 Degree-Sign revealed radial asymmetry in the MTF resulting from the square pixel aperture (0.2 mm Multiplication-Sign 0.2 mm), a characteristic which was not necessarily appreciated with the orthogonal 1D MTF measurements. In simulation experiments, both slit- and edge-based measurements resolved the radial asymmetries in the 2D MTF. The average absolute relative accuracy error in the 2D MTF between the DC and cutoff (2.5 mm{sup -1}) frequencies was 0.13% with average relative precision error of 0.11%. Other simulation results were similar to those derived from physical data. Conclusions: Overall, the general availability, acceptance, accuracy, and ease of implementation of 1D test devices for MTF assessment make this a valuable technique for 2D MTF estimation.« less

WE-D-204-02: Novel Method for Correcting Degradation of Sharpness of Liquid-Crystal Display Based On Modulation Transfer Function

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

Tokurei, S; Department of Radiology, Yamaguchi University Hospital, Ube, Yamaguchi; Morishita, J

2015-06-15

Purpose: To develop a method for improving sharpness of images reproduced on liquid-crystal displays (LCDs) by compensating for the degradation of modulation transfer function (MTF) of the LCD. Methods: The inherent MTF of a color LCD (display MTF) was measured using a commercially available color digital camera. The frequency responses necessary to compensate for the resolution property of the LCD were calculated from the inverses of the display MTFs in both the horizontal and vertical directions. In addition, the inverses of the display MTFs were combined with the response of the human eye. The finite impulse response (FIR) filters weremore » computed by taking the inverse Fourier transform of the frequency responses, and the effects of the FIR filtering on both the resolution and noise properties of the displayed images were verified by measuring the MTF and Wiener spectrum (WS), respectively. The FIR filtering was then applied to the representation of digital bone and chest radiographs. Results: The FIR filtering improved the MTF values by up to almost 1.0 or greater over the frequency range of interest, while it minimally increased the WS values. Combining the inverses of the display MTFs with the response of the human eye led to further refinement of the MTF. Our method was successfully and beneficially applied to the image interpretation of bone radiographs. The resolution enhancement of chest radiographs, which include larger scattered radiation than bone radiographs, was easily perceived by incorporating the response of the human eye. In addition, no artifacts were observed on the processed images. Conclusion: Our proposed method to compensate for the degradation of the resolution properties of LCDs has the potential to improve the observer performance of radiologists when reading digital radiographs. This work was supported in part by grant from EIZO Corporation.« less

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

Novak, Erik; Trolinger, James D.; Lacey, Ian

This work reports on the development of a binary pseudo-random test sample optimized to calibrate the MTF of optical microscopes. The sample consists of a number of 1-D and 2-D patterns, with different minimum sizes of spatial artifacts from 300 nm to 2 microns. We describe the mathematical background, fabrication process, data acquisition and analysis procedure to return spatial frequency based instrument calibration. We show that the developed samples satisfy the characteristics of a test standard: functionality, ease of specification and fabrication, reproducibility, and low sensitivity to manufacturing error. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading ofmore » the abstract is permitted for personal use only.« less

MTF evaluation of in-line phase contrast imaging system

NASA Astrophysics Data System (ADS)

Sun, Xiaoran; Gao, Feng; Zhao, Huijuan; Zhang, Limin; Li, Jiao; Zhou, Zhongxing

2017-02-01

X-ray phase contrast imaging (XPCI) is a novel method that exploits the phase shift for the incident X-ray to form an image. Various XPCI methods have been proposed, among which, in-line phase contrast imaging (IL-PCI) is regarded as one of the most promising clinical methods. The contrast of the interface is enhanced due to the introduction of the boundary fringes in XPCI, thus it is generally used to evaluate the image quality of XPCI. But the contrast is a comprehensive index and it does not reflect the information of image quality in the frequency range. The modulation transfer function (MTF), which is the Fourier transform of the system point spread function, is recognized as the metric to characterize the spatial response of conventional X-ray imaging system. In this work, MTF is introduced into the image quality evaluation of the IL-PCI system. Numerous simulations based on Fresnel - Kirchhoff diffraction theory are performed with varying system settings and the corresponding MTFs were calculated for comparison. The results show that MTF can provide more comprehensive information of image quality comparing to contrast in IL-PCI.

Spatial resolution characterization of differential phase contrast CT systems via modulation transfer function (MTF) measurements

NASA Astrophysics Data System (ADS)

Li, Ke; Zambelli, Joseph; Bevins, Nicholas; Ge, Yongshuai; Chen, Guang-Hong

2013-06-01

By adding a Talbot-Lau interferometer to a conventional x-ray absorption computed tomography (CT) imaging system, both differential phase contrast (DPC) signal and absorption contrast signal can be simultaneously measured from the same set of CT measurements. The imaging performance of such multi-contrast x-ray CT imaging systems can be characterized with standard metrics such as noise variance, noise power spectrum, contrast-to-noise ratio, modulation transfer function (MTF), and task-based detectability index. Among these metrics, the measurement of the MTF can be challenging in DPC-CT systems due to several confounding factors such as phase wrapping and the difficulty of using fine wires as probes. To address these technical challenges, this paper discusses a viable and reliable method to experimentally measure the MTF of DPC-CT. It has been found that the spatial resolution of DPC-CT is degraded, when compared to that of the corresponding absorption CT, due to the presence of a source grating G0 in the Talbot-Lau interferometer. An effective MTF was introduced and experimentally estimated to describe the impact of the Talbot-Lau interferometer on the system MTF.

Modulation transfer function estimation of optical lens system by adaptive neuro-fuzzy methodology

NASA Astrophysics Data System (ADS)

Petković, Dalibor; Shamshirband, Shahaboddin; Pavlović, Nenad T.; Anuar, Nor Badrul; Kiah, Miss Laiha Mat

2014-07-01

The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the adaptive neuro-fuzzy (ANFIS) estimator is designed and adapted to estimate MTF value of the actual optical system. Neural network in ANFIS adjusts parameters of membership function in the fuzzy logic of the fuzzy inference system. The back propagation learning algorithm is used for training this network. This intelligent estimator is implemented using Matlab/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method.

Error of the slanted edge method for measuring the modulation transfer function of imaging systems.

PubMed

Xie, Xufen; Fan, Hongda; Wang, Hongyuan; Wang, Zebin; Zou, Nianyu

2018-03-01

The slanted edge method is a basic approach for measuring the modulation transfer function (MTF) of imaging systems; however, its measurement accuracy is limited in practice. Theoretical analysis of the slanted edge MTF measurement method performed in this paper reveals that inappropriate edge angles and random noise reduce this accuracy. The error caused by edge angles is analyzed using sampling and reconstruction theory. Furthermore, an error model combining noise and edge angles is proposed. We verify the analyses and model with respect to (i) the edge angle, (ii) a statistical analysis of the measurement error, (iii) the full width at half-maximum of a point spread function, and (iv) the error model. The experimental results verify the theoretical findings. This research can be referential for applications of the slanted edge MTF measurement method.

[A method of measuring presampled modulation transfer function using a rationalized approximation of geometrical edge slope].

PubMed

Honda, Michitaka

2014-04-01

Several improvements were implemented in the edge method of presampled modulation transfer function measurements (MTFs). The estimation technique for edge angle was newly developed by applying an algorithm for principal components analysis. The error in the estimation was statistically confirmed to be less than 0.01 even in the presence of quantum noise. Secondly, the geometrical edge slope was approximated using a rationalized number, making it possible to obtain an oversampled edge response function (ESF) with equal intervals. Thirdly, the final MTFs were estimated using the average of multiple MTFs calculated for local areas. This averaging operation eliminates the errors caused by the rationalized approximation. Computer-simulated images were used to evaluate the accuracy of our method. The relative error between the estimated MTF and the theoretical MTF at the Nyquist frequency was less than 0.5% when the MTF was expressed as a sinc function. For MTFs representing an indirect detector and phase-contrast detector, good agreement was also observed for the estimated MTFs for each. The high accuracy of the MTF estimation was also confirmed, even for edge angles of around 10 degrees, which suggests the potential for simplification of the measurement conditions. The proposed method could be incorporated into an automated measurement technique using a software application.

Co-Administration of Metformin and N-Acetyl Cysteine Fails to Improve Clinical Manifestations in PCOS Individual Undergoing ICSI

PubMed Central

Cheraghi, Ebrahim; Soleimani Mehranjani, Malek; Shariatzadeh, Mohammad Ali; Nasr Esfahani, Mohammad Hossein; Ebrahimi, Zahra

2014-01-01

Background Studies have demonstrated the efficacy of metformin (MTF ) in reducing insulin resistance and N-acetyl cysteine (NAC) in inhibiting oxidative stress which are involved in the pathogenesis of polycystic ovarian syndrome (PCOS). We aimed to compare the effects of MTF and NAC combination on serum metabolite and hormonal levels during the course of ovulation induction in PCOS individual candidates of intracytoplasmic sperm injection (ICSI). Materials and Methods In this prospective randomized clinical trial, placebo con- trolled pilot study, 80 patients of polycystic ovarian syndrome at the age of 25-35 years were divided into 4 groups (n=20): i. NAC=treated with N-acetyl cysteine (600 mg three times daily), ii. MTF=treated with metformin (500 mg three times daily), iii. MTF+NAC=treated with N-acetyl cysteine plus metformin (the offered doses) and iv. placebo (PLA). A total number of 20 patients (6 from MTF group, 4 from NAC group, 6 from MTF+NAC group and 4 from PLA group) were dropped of the study. The drugs were administrated from day 3 of menses of previous cycle until ovum pick-up. Results Serum levels of luteinizing hormone (LH), total testosterone, cholester- ol and triglyceride, insulin and leptin significantly reduced in the MTF and NAC groups compared to the placebo (p<0.01). But levels of LH, total testosterone, cholesterol and triglyceride had no significant reduction in the MTF+NAC groups compared to the placebo. The serum levels of malonyldialdehyde (MDA), insulin and leptin reduced significantly after treatment in the MTF+NAC group compared to the placebo (p<0.05). Conclusion Considering the adverse effect of combination therapy, we proposed the conadministration might have no beneficial effect for PCOS patient during course of ovulation induction of ICSI (Registration Number: IRCT201204159476N1). PMID:25083175

On use of image quality metrics for perceptual blur modeling: image/video compression case

NASA Astrophysics Data System (ADS)

Cha, Jae H.; Olson, Jeffrey T.; Preece, Bradley L.; Espinola, Richard L.; Abbott, A. Lynn

2018-02-01

Linear system theory is employed to make target acquisition performance predictions for electro-optical/infrared imaging systems where the modulation transfer function (MTF) may be imposed from a nonlinear degradation process. Previous research relying on image quality metrics (IQM) methods, which heuristically estimate perceived MTF has supported that an average perceived MTF can be used to model some types of degradation such as image compression. Here, we discuss the validity of the IQM approach by mathematically analyzing the associated heuristics from the perspective of reliability, robustness, and tractability. Experiments with standard images compressed by x.264 encoding suggest that the compression degradation can be estimated by a perceived MTF within boundaries defined by well-behaved curves with marginal error. Our results confirm that the IQM linearizer methodology provides a credible tool for sensor performance modeling.

Accurate and cost-effective MTF measurement system for lens modules of digital cameras

NASA Astrophysics Data System (ADS)

Chang, Gao-Wei; Liao, Chia-Cheng; Yeh, Zong-Mu

2007-01-01

For many years, the widening use of digital imaging products, e.g., digital cameras, has given rise to much attention in the market of consumer electronics. However, it is important to measure and enhance the imaging performance of the digital ones, compared to that of conventional cameras (with photographic films). For example, the effect of diffraction arising from the miniaturization of the optical modules tends to decrease the image resolution. As a figure of merit, modulation transfer function (MTF) has been broadly employed to estimate the image quality. Therefore, the objective of this paper is to design and implement an accurate and cost-effective MTF measurement system for the digital camera. Once the MTF of the sensor array is provided, that of the optical module can be then obtained. In this approach, a spatial light modulator (SLM) is employed to modulate the spatial frequency of light emitted from the light-source. The modulated light going through the camera under test is consecutively detected by the sensors. The corresponding images formed from the camera are acquired by a computer and then, they are processed by an algorithm for computing the MTF. Finally, through the investigation on the measurement accuracy from various methods, such as from bar-target and spread-function methods, it appears that our approach gives quite satisfactory results.

Measurements of system sharpness for two digital breast tomosynthesis systems

NASA Astrophysics Data System (ADS)

Marshall, N. W.; Bosmans, H.

2012-11-01

The aim of this work was to propose system sharpness parameters for digital breast tomosynthesis (DBT) systems that include the influence of focus size and focus motion for use in quality assurance protocols. X-ray focus size was measured using a multiple pinhole test object, while detector presampling modulation transfer function (MTF) was measured from projection images of a 10 cm × 10 cm, 1 mm thick steel edge, for the Siemens Inspiration and Hologic Selenia Dimensions DBT systems. The height of the edge above the table was then varied from 1 to 78 mm. The MTF expected from theory for the projection images was calculated from the measured detector MTF, focus size MTF and focus motion MTF and was compared against measured curves. Two methods were used to measure the in-plane MTF in the DBT volume: a tungsten wire of diameter 25 µm and an Al edge 0.2 mm thick, both imaged with a 15 mm thick poly(methyl methacrylate) (PMMA) plate. The in-depth point spread function (PSF) was measured using an angled tungsten wire. The full 3D MTF was estimated with a 0.5 mm diameter aluminium bead held in a 45 mm thick PMMA phantom, with the bead 15 and 65 mm above the table. Inspiration DBT projection images are saved at native detector resolution (85 µm), while the Dimensions re-bins projections to 140 µm pixels (2 × 2 binning); both systems used 2 × 2 binning of projection data before reconstruction. The 50% point for the MTF (MTF0.50) measured in the DBT projection images for the tube-travel direction fell as a function of height above the table from 3.60 to 0.90 mm-1 for the Inspiration system and from 2.50 to 1.20 mm-1 for the Dimensions unit. The maximum deviation of measured MTF0.50 from the calculated value was 13%. MTF0.50 measured in-plane (tube-travel direction) fell as a function of height above the table from 1.66 to 0.97 mm-1 for the Inspiration system and from 2.21 to 1.31 mm-1 for the Dimensions system. The full-width half-maximum for the in-depth PSF was 3.0 and 5.9 mm for the Inspiration and Dimensions systems, respectively. There was no difference in the 3D MTF curves, sectioned in the tube-travel direction, for bead heights of 15 and 65 mm above the table. A 25 µm tungsten wire held within a 15 mm thick PMMA plate was found to be a suitable test object for measurement of in-plane MTF. Evaluation of MTF as a function of height above the table, both in the projection images and in the reconstructed planes, provides important information on the impact of focus size and focus motion on the DBT system's imaging performance.

Measurements of system sharpness for two digital breast tomosynthesis systems.

PubMed

Marshall, N W; Bosmans, H

2012-11-21

The aim of this work was to propose system sharpness parameters for digital breast tomosynthesis (DBT) systems that include the influence of focus size and focus motion for use in quality assurance protocols. X-ray focus size was measured using a multiple pinhole test object, while detector presampling modulation transfer function (MTF) was measured from projection images of a 10 cm × 10 cm, 1 mm thick steel edge, for the Siemens Inspiration and Hologic Selenia Dimensions DBT systems. The height of the edge above the table was then varied from 1 to 78 mm. The MTF expected from theory for the projection images was calculated from the measured detector MTF, focus size MTF and focus motion MTF and was compared against measured curves. Two methods were used to measure the in-plane MTF in the DBT volume: a tungsten wire of diameter 25 µm and an Al edge 0.2 mm thick, both imaged with a 15 mm thick poly(methyl methacrylate) (PMMA) plate. The in-depth point spread function (PSF) was measured using an angled tungsten wire. The full 3D MTF was estimated with a 0.5 mm diameter aluminium bead held in a 45 mm thick PMMA phantom, with the bead 15 and 65 mm above the table. Inspiration DBT projection images are saved at native detector resolution (85 µm), while the Dimensions re-bins projections to 140 µm pixels (2 × 2 binning); both systems used 2 × 2 binning of projection data before reconstruction. The 50% point for the MTF (MTF(0.50)) measured in the DBT projection images for the tube-travel direction fell as a function of height above the table from 3.60 to 0.90 mm(-1) for the Inspiration system and from 2.50 to 1.20 mm(-1) for the Dimensions unit. The maximum deviation of measured MTF(0.50) from the calculated value was 13%. MTF(0.50) measured in-plane (tube-travel direction) fell as a function of height above the table from 1.66 to 0.97 mm(-1) for the Inspiration system and from 2.21 to 1.31 mm(-1) for the Dimensions system. The full-width half-maximum for the in-depth PSF was 3.0 and 5.9 mm for the Inspiration and Dimensions systems, respectively. There was no difference in the 3D MTF curves, sectioned in the tube-travel direction, for bead heights of 15 and 65 mm above the table. A 25 µm tungsten wire held within a 15 mm thick PMMA plate was found to be a suitable test object for measurement of in-plane MTF. Evaluation of MTF as a function of height above the table, both in the projection images and in the reconstructed planes, provides important information on the impact of focus size and focus motion on the DBT system's imaging performance.

Spatial resolution measurements by Radia diagnostic software with SEDENTEXCT image quality phantom in cone beam CT for dental use.

PubMed

Watanabe, Hiroshi; Nomura, Yoshikazu; Kuribayashi, Ami; Kurabayashi, Tohru

2018-02-01

We aimed to employ the Radia diagnostic software with the safety and efficacy of a new emerging dental X-ray modality (SEDENTEXCT) image quality (IQ) phantom in CT, and to evaluate its validity. The SEDENTEXCT IQ phantom and Radia diagnostic software were employed. The phantom was scanned using one medical full-body CT and two dentomaxillofacial cone beam CTs. The obtained images were imported to the Radia software, and the spatial resolution outputs were evaluated. The oversampling method was employed using our original wire phantom as a reference. The resultant modulation transfer function (MTF) curves were compared. The null hypothesis was that MTF curves generated using both methods would be in agreement. One-way analysis of variance tests were applied to the f50 and f10 values from the MTF curves. The f10 values were subjectively confirmed by observing the line pair modules. The Radia software reported the MTF curves on the xy-plane of the CT scans, but could not return f50 and f10 values on the z-axis. The null hypothesis concerning the reported MTF curves on the xy-plane was rejected. There were significant differences between the results of the Radia software and our reference method, except for f10 values in CS9300. These findings were consistent with our line pair observations. We evaluated the validity of the Radia software with the SEDENTEXCT IQ phantom. The data provided were semi-automatic, albeit with problems and statistically different from our reference. We hope the manufacturer will overcome these limitations.

First in-flight results of Pleiades 1A innovative methods for optical calibration

NASA Astrophysics Data System (ADS)

Kubik, Philippe; Lebègue, Laurent; Fourest, Sébastien; Delvit, Jean-Marc; de Lussy, Françoise; Greslou, Daniel; Blanchet, Gwendoline

2017-11-01

The PLEIADES program is a space Earth Observation system led by France, under the leadership of the French Space Agency (CNES). Since it was successfully launched on December 17th, 2011, Pleiades 1A high resolution optical satellite has been thoroughly tested and validated during the commissioning phase led by CNES. The whole system has been designed to deliver submetric optical images to users whose needs were taken into account very early in the design process. This satellite opens a new era in Europe since its off-nadir viewing capability delivers a worldwide 2- days access, and its great agility will make possible to image numerous targets, strips and stereo coverage from the same orbit. Its imaging capability of more than 450 images of 20 km x 20 km per day can fulfill a broad spectrum of applications for both civilian and defence users. For an earth observing satellite with no on-board calibration source, the commissioning phase is a critical quest of wellcharacterized earth landscapes and ground patterns that have to be imaged by the camera in order to compute or fit the parameters of the viewing models. It may take a long time to get the required scenes with no cloud, whilst atmosphere corrections need simultaneous measurements that are not always possible. The paper focuses on new in-flight calibration methods that were prepared before the launch in the framework of the PLEIADES program : they take advantage of the satellite agility that can deeply relax the operational constraints and may improve calibration accuracy. Many performances of the camera were assessed thanks to a dedicated innovative method that was successfully validated during the commissioning period : Modulation Transfer Function (MTF), refocusing, absolute calibration, line of sight stability were estimated on stars and on the Moon. Detectors normalization and radiometric noise were computed on specific pictures on Earth with a dedicated guidance profile. Geometric viewing frame was determined with a particular image acquisition combining different views of the same target. All these new methods are expected to play a key role in the future when active optics will need sophisticated in-flight calibration strategy.

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

Gislason-Lee, Amber J., E-mail: A.J.Gislason@leeds.ac.uk; Tunstall, Clare M.; Kengyelics, Stephen K.

Purpose: Cardiac x-ray detectors are used to acquire moving images in real-time for angiography and interventional procedures. Detective quantum efficiency (DQE) is not generally measured on these dynamic detectors; the required “for processing” image data and control of x-ray settings have not been accessible. By 2016, USA hospital physicists will have the ability to measure DQE and will likely utilize the International Electrotechnical Commission (IEC) standard for measuring DQE of dynamic x-ray imaging devices. The current IEC standard requires an image of a tilted tungsten edge test object to obtain modulation transfer function (MTF) for DQE calculation. It specifies themore » range of edge angles to use; however, it does not specify a preferred method to determine this angle for image analysis. The study aimed to answer the question “will my choice in method impact my results?” Four different established edge angle determination methods were compared to investigate the impact on DQE. Methods: Following the IEC standard, edge and flat field images were acquired on a cardiac flat-panel detector to calculate MTF and noise power spectrum, respectively, to determine DQE. Accuracy of the methods in determining the correct angle was ascertained using a simulated edge image with known angulations. Precision of the methods was ascertained using variability of MTF and DQE, calculated via bootstrapping. Results: Three methods provided near equal angles and the same MTF while the fourth, with an angular difference of 6%, had a MTF lower by 3% at 1.5 mm{sup −1} spatial frequency and 8% at 2.5 mm{sup −1}; corresponding DQE differences were 6% at 1.5 mm{sup −1} and 17% at 2.5 mm{sup −1}; differences were greater than standard deviations in the measurements. Conclusions: DQE measurements may vary by a significant amount, depending on the method used to determine the edge angle when following the IEC standard methodology for a cardiac x-ray detector. The most accurate and precise methods are recommended for absolute assessments and reproducible measurements, respectively.« less

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

Li, G; Nishino, T; Greene, T

Purpose: To determine the consistency of digital detector (DR) tests recommended by AAPM TG150 and tests provided by commercially available DirectView Total Quality Tool (TQT). Methods: The DR tests recommended by the TG150 Detector Subgroup[1] were performed on 4 new Carestream DRX-Revolution and one Carestream DRX1C retrofit of a GE AMX-4 that had been in service for three years. After detector calibration, flat-field images plus images of two bar patterns oriented parallel and perpendicular to the A-C axis, were acquired at conditions recommended by TG150. Raw images were harvested and then analyzed using a MATLAB software previously validated[2,3,4]. Data weremore » analyzed using ROIs of two different dimensions: 1) 128 x 128 ROIs matching the detector electronics; and 2) 256 x 256 ROIs, each including 4 adjacent smaller ROIs. TG150 metrics from 128 x 128 ROIs were compared to TQT metrics, which are also obtained from 128 x 128 ROIs[5]. Results: The results show that both TG150 and TQT measurements were consistent among these detectors. Differences between TG150 and TQT values appear systematic. Compared with 128 x 128 ROIs, noise and SNR non-uniformity were lower with 256 x 256 ROIs, although signal non-uniformity was similar, indicating detectors were appropriately calibrated for gain and offset. MTF of the retrofit unit remained essentially the same between 2012 and 2015, but was inferior to the new units. The older generator focal spot is smaller (0.75mm vs. 1.2mm), and the SID for acquisition is 182cm as well, so focal spot dimensions cannot explain the difference. The difference in MTF may be secondary to differences in generator X-ray spectrum or by unannounced changes in detector architecture. Further investigation is needed. Conclusion: The study shows that both TG150 and TQT tests are consistent. The numerical value of some metrics are dependent on ROI size.« less

Estimation of the two-dimensional presampled modulation transfer function of digital radiography devices using one-dimensional test objects.

PubMed

Wells, Jered R; Dobbins, James T

2012-10-01

The modulation transfer function (MTF) of medical imaging devices is commonly reported in the form of orthogonal one-dimensional (1D) measurements made near the vertical and horizontal axes with a slit or edge test device. A more complete description is found by measuring the two-dimensional (2D) MTF. Some 2D test devices have been proposed, but there are some issues associated with their use: (1) they are not generally available; (2) they may require many images; (3) the results may have diminished accuracy; and (4) their implementation may be particularly cumbersome. This current work proposes the application of commonly available 1D test devices for practical and accurate estimation of the 2D presampled MTF of digital imaging systems. Theory was developed and applied to ensure adequate fine sampling of the system line spread function for 1D test devices at orientations other than approximately vertical and horizontal. Methods were also derived and tested for slit nonuniformity correction at arbitrary angle. Techniques were validated with experimental measurements at ten angles using an edge test object and three angles using a slit test device on an indirect-detection flat-panel system [GE Revolution XQ∕i (GE Healthcare, Waukesha, WI)]. The 2D MTF was estimated through a simple surface fit with interpolation based on Delaunay triangulation of the 1D edge-based MTF measurements. Validation by synthesis was also performed with simulated images from a hypothetical direct-detection flat-panel device. The 2D MTF derived from physical measurements yielded an average relative precision error of 0.26% for frequencies below the cutoff (2.5 mm(-1)) and approximate circular symmetry at frequencies below 4 mm(-1). While slit analysis generally agreed with the results of edge analysis, the two showed subtle differences at frequencies above 4 mm(-1). Slit measurement near 45° revealed radial asymmetry in the MTF resulting from the square pixel aperture (0.2 mm × 0.2 mm), a characteristic which was not necessarily appreciated with the orthogonal 1D MTF measurements. In simulation experiments, both slit- and edge-based measurements resolved the radial asymmetries in the 2D MTF. The average absolute relative accuracy error in the 2D MTF between the DC and cutoff (2.5 mm(-1)) frequencies was 0.13% with average relative precision error of 0.11%. Other simulation results were similar to those derived from physical data. Overall, the general availability, acceptance, accuracy, and ease of implementation of 1D test devices for MTF assessment make this a valuable technique for 2D MTF estimation.

Measured and calculated K-fluorescence effects on the MTF of an amorphous-selenium based CCD x-ray detector.

PubMed

Hunter, David M; Belev, George; Kasap, Safa; Yaffe, Martin J

2012-02-01

Theoretical reasoning suggests that direct conversion digital x-ray detectors based upon photoconductive amorphous-selenium (a-Se) could attain very high values of the MTF (modulation transfer function) at spatial frequencies well beyond 20 cycles mm(-1). One of the fundamental factors affecting resolution loss, particularly at x-ray energies just above the K-edge of selenium (12.66 keV), is the K-fluorescence reabsorption mechanism, wherein energy can be deposited in the detector at locations laterally displaced from the initial x-ray interaction site. This paper compares measured MTF changes above and below the Se K-edge of a CCD based a-Se x-ray detector with theoretical expectations. A prototype 25 μm sampling pitch (Nyquist frequency = 20 cycles mm(-1), 200 μm thick a-Se layer based x-ray detector, utilizing a specialized CCD readout device (200 × 400 area array), was used to make edge images with monochromatic x-rays above and below the K-edge of Se. A vacuum double crystal monochromator, exposed to polychromatic x-rays from a synchrotron, formed the monochromatic x-ray source. The monochromaticity of the x-rays was 99% or better. The presampling MTF was determined using the slanted edge method. The theory modeling the MTF performance of the detector includes the basic x-ray interaction physics in the a-Se layer as well as effects related to the operation of the CCD and charge trapping at a blocking layer present at the CCD/a-Se interface. The MTF performance of the prototype a-Se CCD was reduced from the theoretical value prescribed by the basic Se x-ray interaction physics, principally by the presence of a blocking layer. Nevertheless, the K-fluorescence reduction in the MTF was observed, approximately as predicted by theory. For the CCD prototype detector, at five cycles mm(-1), there was a 14% reduction of the MTF, from a value of 0.7 below the K-edge of Se, to 0.6 just above the K-edge. The MTF of an a-Se x-ray detector has been measured using monochromatic x-rays above and below the K-edge of selenium. The MTF is poorer above the K-edge by an amount consistent with theoretical expectations.

Modeling and measurement of the detector presampling MTF of a variable resolution x-ray CT scanner.

PubMed

Melnyk, Roman; DiBianca, Frank A

2007-03-01

The detector presampling modulation transfer function (MTF) of a 576-channel variable resolution x-ray (VRX) computed tomography (CT) scanner was evaluated in this study. The scanner employs a VRX detector, which provides increased spatial resolution by matching the scanner's field of view (FOV) to the size of an object being imaged. Because spatial resolution is the parameter the scanner promises to improve, the evaluation of this resolution is important. The scanner's pre-reconstruction spatial resolution, represented by the detector presampling MTF, was evaluated using both modeling (Monte Carlo simulation) and measurement (the moving slit method). The theoretical results show the increase in the cutoff frequency of the detector presampling MTF from 1.39 to 43.38 cycles/mm as the FOV of the VRX CT scanner decreases from 32 to 1 cm. The experimental results are in reasonable agreement with the theoretical data. Some discrepancies between the measured and the modeled detector presampling MTFs can be explained by the limitations of the model. At small FOVs (1-8 cm), the MTF measurements were limited by the size of the focal spot. The obtained results are important for further development of the VRX CT scanner.

Modeling and measurement of the detector presampling MTF of a variable resolution x-ray CT scanner

PubMed Central

Melnyk, Roman; DiBianca, Frank A.

2007-01-01

The detector presampling MTF of a 576-channel variable resolution x-ray (VRX) CT scanner was evaluated in this study. The scanner employs a VRX detector, which provides increased spatial resolution by matching the scanner’s field of view (FOV) to the size of an object being imaged. Because spatial resolution is the parameter the scanner promises to improve, the evaluation of this resolution is important. The scanner’s pre-reconstruction spatial resolution, represented by the detector presampling MTF, was evaluated using both modeling (Monte Carlo simulation) and measurement (the moving slit method). The theoretical results show the increase in the cutoff frequency of the detector presampling MTF from 1.39 cy/mm to 43.38 cy/mm as the FOV of the VRX CT scanner decreases from 32 cm to 1 cm. The experimental results are in reasonable agreement with the theoretical data. Some discrepancies between the measured and the modeled detector presampling MTFs can be explained by the limitations of the model. At small FOVs (1–8 cm), the MTF measurements were limited by the size of the focal spot. The obtained results are important for further development of the VRX CT scanner. PMID:17369872

[Drugs for attention deficit hyperactivity disorder].

PubMed

Montañés-Rada, F; Gangoso-Fermoso, A B; Martíínez-Granero, M A

Quantitative studies have highlighted differences in several drugs approved for use in Spain in the treatment of attention deficit hyperactivity disorder. No clear differences are observed, however, in the case of qualitative studies. The number of patients needed to be treated in order for one to reach complete remission (NNT) of methylphenidate (MTF) is from 2.2 to 5, and the effect size (ES) is 0.9. Atomoxetine has an NNT of 4 and an ES of 0.7. The advantages of immediate-release MTF (IR-MTF) over the extended-release version (ER-MTF) lie in its low cost, its flexibility and the better results obtained in quantitative studies. In contrast, ER-MTF offers a lower risk of abuse, needs to be taken fewer times with less need for third parties to control administration, and there is a lower risk of stigmatisation. Combination or changes of IR-MTF and ER-MTF and the combination of MTF with atomoxetine are sometimes necessary to adjust the weekday or weekend doses. Starting treatment with IR-MTF and then maintaining or changing to ER-MTF offers certain advantages as regards safety, dose adjustments and dosage. Atomoxetine is the best alternative if there is a background of adverse events with low or moderate doses of stimulants, or lack of response to high doses of stimulants. In cases of notable comorbid anxiety, both MTF and atomoxetine have the same level of indication. If there is a risk of substance abuse, both atomoxetine and ER-MTF are the preferred treatment. For the other indications, MTF is the preferred treatment.

[Evaluation of the resolving power of different angles in MPR images of 16DAS-MDCT].

PubMed

Kimura, Mikio; Usui, Junshi; Nozawa, Takeo

2007-03-20

In this study, we evaluated the resolving power of three-dimensional (3D) multiplanar reformation (MPR) images with various angles by using 16 data acquisition system multi detector row computed tomography (16DAS-MDCT) . We reconstructed the MPR images using data with a 0.75 mm slice thickness of the axial image in this examination. To evaluate resolving power, we used an original new phantom (RC phantom) that can be positioned at any slice angle in MPR images. We measured the modulation transfer function (MTF) by using the methods of measuring pre-sampling MTF, and used Fourier transform of image data of the square wave chart. The scan condition and image reconstruction condition that were adopted in this study correspond to the condition that we use for three-dimensional computed tomographic angiography (3D-CTA) examination of the head in our hospital. The MTF of MPR images showed minimum values at slice angles in parallel with the axial slice, and showed maximum values at the sagittal slice and coronal slice angles that are parallel to the Z-axis. With an oblique MPR image, MTF did not change with angle changes in the oblique sagittal slice plane, but in the oblique coronal slice plane, MTF increased as the tilt angle increased from the axial plane to the Z plane. As a result, we could evaluate the resolving power of a head 3D image by measuring the MTF of the axial image and sagittal image or the coronal image.

Improvement of the edge method for on-orbit MTF measurement.

PubMed

Viallefont-Robinet, Françoise; Léger, Dominique

2010-02-15

The edge method is a widely used way to assess the on-orbit Modulation Transfer Function (MTF). Since good quality is required for the edge, the higher the spatial resolution, the better the results are. In this case, an artificial target can be built and used to ensure a good edge quality. For moderate spatial resolutions, only natural targets are available. Hence the edge quality is unknown and generally rather poor. Improvements of the method have been researched in order to compensate for the poor quality of natural edges. This has been done through the use of symmetry and/or a transfer function model, which enables the elimination of noise. This has also been used for artificial target. In this case, the use of the model overcomes the incomplete sampling when the target is too small or gives the opportunity to assess the defocus of the sensor. This paper begins with a recall of the method followed by a presentation of the changes relying on transfer function parametric model. The transfer function model and the process corresponding to the changes are described. Applications of these changes for several satellites of the French spatial agency are presented: for SPOT 1, it enables to assess XS MTF with natural edges, for SPOT 5, it enables to use the Salon-de-Provence artificial target for MTF assessment in the HM mode, and for the foreseen Pleiades, it enables to estimate the defocus.

LCD displays performance comparison by MTF measurement using the white noise stimulus method

NASA Astrophysics Data System (ADS)

Mitjà, Carles; Escofet, Jaume

2011-01-01

The amount of images produced to be viewed as soft copies on output displays are significantly increasing. This growing occurs at the expense of the images targeted to hard copy versions on paper or any other physical support. Even in the case of high quality hard copy production, people working in professional imaging uses different displays in selecting, editing, processing and showing images, from laptop screen to specialized high end displays. Then, the quality performance of these devices is crucial in the chain of decisions to be taken in image production. Metrics of this quality performance can help in the equipment acquisition. Different metrics and methods have been described to determine the quality performance of CRT and LCD computer displays in clinical area. One of most important metrics in this field is the device spatial frequency response obtained measuring the modulation transfer function (MTF). This work presents a comparison between the MTF of three different LCD displays, Apple MacBook Pro 15", Apple LED Cinema Display 24" and Apple iPhone4, measured by the white noise stimulus method, over vertical and horizontal directions. Additionally, different displays show particular pixels structure pattern. In order to identify this pixel structure, a set of high magnification images is taken from each display to be related with the respective vertical and horizontal MTF.

Imaging quality evaluation method of pixel coupled electro-optical imaging system

NASA Astrophysics Data System (ADS)

He, Xu; Yuan, Li; Jin, Chunqi; Zhang, Xiaohui

2017-09-01

With advancements in high-resolution imaging optical fiber bundle fabrication technology, traditional photoelectric imaging system have become ;flexible; with greatly reduced volume and weight. However, traditional image quality evaluation models are limited by the coupling discrete sampling effect of fiber-optic image bundles and charge-coupled device (CCD) pixels. This limitation substantially complicates the design, optimization, assembly, and evaluation image quality of the coupled discrete sampling imaging system. Based on the transfer process of grayscale cosine distribution optical signal in the fiber-optic image bundle and CCD, a mathematical model of coupled modulation transfer function (coupled-MTF) is established. This model can be used as a basis for following studies on the convergence and periodically oscillating characteristics of the function. We also propose the concept of the average coupled-MTF, which is consistent with the definition of traditional MTF. Based on this concept, the relationships among core distance, core layer radius, and average coupled-MTF are investigated.

Improvements In The Calculation Of White Light Modulation Transfer Function (MTF) In Japan Optical Engineering Research Association (JOERA)

NASA Astrophysics Data System (ADS)

Minami, Setsuo; Ogawa, Ryota

1980-09-01

Consequences of the working project formed in JOERA (JAPAN OPTICAL ENGINEERING RESEARCH ASSOCIATION) from 1976 to 1978 are to be reported. The question, "What is the most reasonable number of mesh divides of entrance pupil to get monochromatic OTF and the most economical sampling method of spectral wavelengths to calculate White Light MTF?" is important in the actual stage of designing to optimize the conflict relationship between numerical accuracy and computing time. We have examined the spectral characteristics of OTF using some typical lenses such as photographic telephoto lens and wide angled retrofocus lens, cleared the structure of the White Light MTF, and found some techniques to get the reasonable numerical results. As a result of trial experiments to get coincidence between measurements and calculat-ions, the standard filter, which should be added to the MTF lens tester and whose spectral transmittance should be installed in the calculation, are proposed.

The effect of intrinsic attenuation correction methods on the stationarity of the 3-D modulation transfer function of SPECT.

PubMed

Glick, S J; Hawkins, W G; King, M A; Penney, B C; Soares, E J; Byrne, C L

1992-01-01

The application of stationary restoration techniques to SPECT images assumes that the modulation transfer function (MTF) of the imaging system is shift invariant. It was hypothesized that using intrinsic attenuation correction (i.e., methods which explicitly invert the exponential radon transform) would yield a three-dimensional (3-D) MTF which varies less with position within the transverse slices than the combined conjugate view two-dimensional (2-D) MTF varies with depth. Thus the assumption of shift invariance would become less of an approximation for 3-D post- than for 2-D pre-reconstruction restoration filtering. SPECT acquisitions were obtained from point sources located at various positions in three differently shaped, water-filled phantoms. The data were reconstructed with intrinsic attenuation correction, and 3-D MTFs were calculated. Four different intrinsic attenuation correction methods were compared: (1) exponentially weighted backprojection, (2) a modified exponentially weighted backprojection as described by Tanaka et al. [Phys. Med. Biol. 29, 1489-1500 (1984)], (3) a Fourier domain technique as described by Bellini et al. [IEEE Trans. ASSP 27, 213-218 (1979)], and (4) the circular harmonic transform (CHT) method as described by Hawkins et al. [IEEE Trans. Med. Imag. 7, 135-148 (1988)]. The dependence of the 3-D MTF obtained with these methods, on point source location within an attenuator, and on shape of the attenuator, was studied. These 3-D MTFs were compared to: (1) those MTFs obtained with no attenuation correction, and (2) the depth dependence of the arithmetic mean combined conjugate view 2-D MTFs.(ABSTRACT TRUNCATED AT 250 WORDS)

The transcription factor MTF-1 is essential for basal and heavy metal-induced metallothionein gene expression.

PubMed

Heuchel, R; Radtke, F; Georgiev, O; Stark, G; Aguet, M; Schaffner, W

1994-06-15

We have described and cloned previously a factor (MTF-1) that binds specifically to heavy metal-responsive DNA sequence elements in the enhancer/promoter region of metallothionein genes. MTF-1 is a protein of 72.5 kDa that contains six zinc fingers and multiple domains for transcriptional activation. Here we report the disruption of both alleles of the MTF-1 gene in mouse embryonic stem cells by homologous recombination. The resulting null mutant cell line fails to produce detectable amounts of MTF-1. Moreover, due to the loss of MTF-1, the endogenous metallothionein I and II genes are silent, indicating that MTF-1 is required for both their basal and zinc-induced transcription. In addition to zinc, other heavy metals, including cadmium, copper, nickel and lead, also fail to activate metal-responsive promoters in null mutant cells. However, cotransfection of an MTF-1 expression vector and metal-responsive reporter genes yields strong basal transcription that can be further boosted by zinc treatment of cells. These results demonstrate that MTF-1 is essential for metallothionein gene regulation. Finally, we present evidence that MTF-1 itself is a zinc sensor, which exhibits increased DNA binding activity upon zinc treatment.

On-Orbit MTF Measurement and Product Quality Monitoring for Commercial Remote Sensing Systems

NASA Technical Reports Server (NTRS)

Person, Steven

2007-01-01

Initialization and opportunistic targets are chosen that represent the MTF on the spatial domain. Ideal targets have simple mathematical relationships. Determine the MTF of an on-orbit satellite using in-scene targets: Slant-Edge, Line Source, point Source, and Radial Target. Attempt to facilitate the MTF calculation by automatically locating targets of opportunity. Incorporate MTF results into a product quality monitoring architecture.

Inhibition of endogenous MTF-1 signaling in zebrafish embryos identifies novel roles for MTF-1 in development.

PubMed

O'Shields, Britton; McArthur, Andrew G; Holowiecki, Andrew; Kamper, Martin; Tapley, Jeffrey; Jenny, Matthew J

2014-09-01

The metal responsive element-binding transcription factor-1 (MTF-1) responds to changes in cellular zinc levels caused by zinc exposure or disruption of endogenous zinc homeostasis by heavy metals or oxygen-related stress. Here we report the functional characterization of a complete zebrafish MTF-1 in comparison with the previously identified isoform lacking the highly conserved cysteine-rich motif (Cys-X-Cys-Cys-X-Cys) found in all other vertebrate MTF-1 orthologs. In an effort to develop novel molecular tools, a constitutively nuclear dominant-negative MTF-1 (dnMTF-1) was generated as tool for inhibiting endogenous MTF-1 signaling. The in vivo efficacy of the dnMTF-1 was determined by microinjecting in vitro transcribed dnMTF-1 mRNA into zebrafish embryos (1-2 cell stage) followed by transcriptomic profiling using an Agilent 4x44K array on 28- and 36-hpf embryos. A total of 594 and 560 probes were identified as differentially expressed at 28hpf and 36hpf, respectively, with interesting overlaps between timepoints. The main categories of genes affected by the inhibition of MTF-1 signaling were: nuclear receptors and genes involved in stress signaling, neurogenesis, muscle development and contraction, eye development, and metal homeostasis, including novel observations in iron and heme homeostasis. Finally, we investigate both the transcriptional activator and transcriptional repressor role of MTF-1 in potential novel target genes identified by transcriptomic profiling during early zebrafish development. Copyright © 2014 Elsevier B.V. All rights reserved.

Imaging quality analysis of multi-channel scanning radiometer

NASA Astrophysics Data System (ADS)

Fan, Hong; Xu, Wujun; Wang, Chengliang

2008-03-01

Multi-channel scanning radiometer, on boarding FY-2 geostationary meteorological satellite, plays a key role in remote sensing because of its wide field of view and continuous multi-spectral images acquirements. It is significant to evaluate image quality after performance parameters of the imaging system are validated. Several methods of evaluating imaging quality are discussed. Of these methods, the most fundamental is the MTF. The MTF of photoelectric scanning remote instrument, in the scanning direction, is the multiplication of optics transfer function (OTF), detector transfer function (DTF) and electronics transfer function (ETF). For image motion compensation, moving speed of scanning mirror should be considered. The optical MTF measurement is performed in both the EAST/WEST and NORTH/SOUTH direction, whose values are used for alignment purposes and are used to determine the general health of the instrument during integration and testing. Imaging systems cannot perfectly reproduce what they see and end up "blurring" the image. Many parts of the imaging system can cause blurring. Among these are the optical elements, the sampling of the detector itself, post-processing, or the earth's atmosphere for systems that image through it. Through theory calculation and actual measurement, it is proved that DTF and ETF are the main factors of system MTF and the imaging quality can satisfy the requirement of instrument design.

Numerical simulation of the modulation transfer function (MTF) in infrared focal plane arrays: simulation methodology and MTF optimization

NASA Astrophysics Data System (ADS)

Schuster, J.

2018-02-01

Military requirements demand both single and dual-color infrared (IR) imaging systems with both high resolution and sharp contrast. To quantify the performance of these imaging systems, a key measure of performance, the modulation transfer function (MTF), describes how well an optical system reproduces an objects contrast in the image plane at different spatial frequencies. At the center of an IR imaging system is the focal plane array (FPA). IR FPAs are hybrid structures consisting of a semiconductor detector pixel array, typically fabricated from HgCdTe, InGaAs or III-V superlattice materials, hybridized with heat/pressure to a silicon read-out integrated circuit (ROIC) with indium bumps on each pixel providing the mechanical and electrical connection. Due to the growing sophistication of the pixel arrays in these FPAs, sophisticated modeling techniques are required to predict, understand, and benchmark the pixel array MTF that contributes to the total imaging system MTF. To model the pixel array MTF, computationally exhaustive 2D and 3D numerical simulation approaches are required to correctly account for complex architectures and effects such as lateral diffusion from the pixel corners. It is paramount to accurately model the lateral di_usion (pixel crosstalk) as it can become the dominant mechanism limiting the detector MTF if not properly mitigated. Once the detector MTF has been simulated, it is directly decomposed into its constituent contributions to reveal exactly what is limiting the total detector MTF, providing a path for optimization. An overview of the MTF will be given and the simulation approach will be discussed in detail, along with how different simulation parameters effect the MTF calculation. Finally, MTF optimization strategies (crosstalk mitigation) will be discussed.

The Putative C2H2 Transcription Factor MtfA Is a Novel Regulator of Secondary Metabolism and Morphogenesis in Aspergillus nidulans

PubMed Central

Ramamoorthy, Vellaisamy; Dhingra, Sourabh; Kincaid, Alexander; Shantappa, Sourabha; Feng, Xuehuan; Calvo, Ana M.

2013-01-01

Secondary metabolism in the model fungus Aspergillus nidulans is controlled by the conserved global regulator VeA, which also governs morphological differentiation. Among the secondary metabolites regulated by VeA is the mycotoxin sterigmatocystin (ST). The presence of VeA is necessary for the biosynthesis of this carcinogenic compound. We identified a revertant mutant able to synthesize ST intermediates in the absence of VeA. The point mutation occurred at the coding region of a gene encoding a novel putative C2H2 zinc finger domain transcription factor that we denominated mtfA. The A. nidulans mtfA gene product localizes at nuclei independently of the illumination regime. Deletion of the mtfA gene restores mycotoxin biosynthesis in the absence of veA, but drastically reduced mycotoxin production when mtfA gene expression was altered, by deletion or overexpression, in A. nidulans strains with a veA wild-type allele. Our study revealed that mtfA regulates ST production by affecting the expression of the specific ST gene cluster activator aflR. Importantly, mtfA is also a regulator of other secondary metabolism gene clusters, such as genes responsible for the synthesis of terrequinone and penicillin. As in the case of ST, deletion or overexpression of mtfA was also detrimental for the expression of terrequinone genes. Deletion of mtfA also decreased the expression of the genes in the penicillin gene cluster, reducing penicillin production. However, in this case, over-expression of mtfA enhanced the transcription of penicillin genes, increasing penicillin production more than 5 fold with respect to the control. Importantly, in addition to its effect on secondary metabolism, mtfA also affects asexual and sexual development in A. nidulans. Deletion of mtfA results in a reduction of conidiation and sexual stage. We found mtfA putative orthologs conserved in other fungal species. PMID:24066102

Modulation transfer function of a triangular pixel array detector.

PubMed

Karimzadeh, Ayatollah

2014-07-01

The modulation transfer function (MTF) is the main parameter that is used to evaluate image quality in electro-optical systems. Detector sampling MTF in most electro-optical systems determines the cutoff frequency of the system. The MTF of the detector depends on its pixel shape. In this work, we calculated the MTF of a detector with an equilateral triangular pixel shape. Some new results were found in deriving the MTF for the equilateral triangular pixel shape.

Increased Cortical Thickness in Male-to-Female Transsexualism

PubMed Central

Luders, Eileen; Sánchez, Francisco J.; Tosun, Duygu; Shattuck, David W.; Gaser, Christian; Vilain, Eric; Toga, Arthur W.

2013-01-01

Background The degree to which one identifies as male or female has a profound impact on one’s life. Yet, there is a limited understanding of what contributes to this important characteristic termed gender identity. In order to reveal factors influencing gender identity, studies have focused on people who report strong feelings of being the opposite sex, such as male-to-female (MTF) transsexuals. Method To investigate potential neuroanatomical variations associated with transsexualism, we compared the regional thickness of the cerebral cortex between 24 MTF transsexuals who had not yet been treated with cross-sex hormones and 24 age-matched control males. Results Results revealed thicker cortices in MTF transsexuals, both within regions of the left hemisphere (i.e., frontal and orbito-frontal cortex, central sulcus, perisylvian regions, paracentral gyrus) and right hemisphere (i.e., pre-/post-central gyrus, parietal cortex, temporal cortex, precuneus, fusiform, lingual, and orbito-frontal gyrus). Conclusion These findings provide further evidence that brain anatomy is associated with gender identity, where measures in MTF transsexuals appear to be shifted away from gender-congruent men. PMID:23724358

Quickbird Satellite in-orbit Modulation Transfer Function (MTF) Measurement Using Edge, Pulse and Impulse Methods for Summer 2003

NASA Technical Reports Server (NTRS)

Helder, Dennis; Choi, Taeyoung; Rangaswamy, Manjunath

2005-01-01

The spatial characteristics of an imaging system cannot be expressed by a single number or simple statement. However, the Modulation Transfer Function (MTF) is one approach to measure the spatial quality of an imaging system. Basically, MTF is the normalized spatial frequency response of an imaging system. The frequency response of the system can be evaluated by applying an impulse input. The resulting impulse response is termed the Point Spread function (PSF). This function is a measure of the amount of blurring present in the imaging system and is itself a useful measure of spatial quality. An underlying assumption is that the imaging system is linear and shift-independent. The Fourier transform of the PSF is called the Optical Transfer Function (OTF) and the normalized magnitude of the OTF is the MTF. In addition to using an impulse input, a knife-edge in technique has also been used in this project. The sharp edge exercises an imaging system at all spatial frequencies. The profile of an edge response from an imaging system is called an Edge Spread Function (ESF). Differentiation of the ESF results in a one-dimensional version of the Point Spread Function (PSF). Finally, MTF can be calculated through use of Fourier transform of the PSF as stated previously. Every image includes noise in some degree which makes MTF of PSF estimation more difficult. To avoid the noise effects, many MTF estimation approaches use smooth numerical models. Historically, Gaussian models and Fermi functions were applied to reduce the random noise in the output profiles. The pulse-input method was used to measure the MTF of the Landsat Thematic Mapper (TM) using 8th order even functions over the San Mateo Bridge in San Francisco, California. Because the bridge width was smaller than the 30-meter ground sample distance (GSD) of the TM, the Nyquist frequency was located before the first zero-crossing point of the sinc function from the Fourier transformation of the bridge pulse. To avoid the zero-crossing points in the frequency domain from a pulse, the pulse width should be less than the width of two pixels (or 2 GSD's), but the short extent of the pulse results in a poor signal-to-noise ratio. Similarly, for a high-resolution satellite imaging system such as Quickbird, the input pulse width was critical because of the zero crossing points and noise present in the background area. It is important, therefore, that the width of the input pulse be appropriately sized. Finally, the MTF was calculated by taking ratio between Fourier transform of output and Fourier transform of input. Regardless of whether the edge, pulse and impulse target method is used, the orientation of the targets is critical in order to obtain uniformly spaced sub-pixel data points. When the orientation is incorrect, sample data points tend to be located in clusters that result in poor reconstruction of the edge or pulse profiles. Thus, a compromise orientation must be selected so that all spectral bands can be accommodated. This report continues by outlining the objectives in Section 2, procedures followed in Section 3, descriptions of the field campaigns in Section 4, results in Section 5, and a brief summary in Section 6.

Intercomparison of methods for image quality characterization. I. Modulation transfer function

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

Samei, Ehsan; Ranger, Nicole T.; Dobbins, James T. III

The modulation transfer function (MTF) and the noise power spectrum (NPS) are widely recognized as the most relevant metrics of resolution and noise performance in radiographic imaging. These quantities have commonly been measured using various techniques, the specifics of which can have a bearing on the accuracy of the results. As a part of a study aimed at comparing the relative performance of different techniques, in this paper we report on a comparison of two established MTF measurement techniques: one using a slit test device [Dobbins et al., Med. Phys. 22, 1581-1593 (1995)] and another using a translucent edge testmore » device [Samei et al., Med. Phys. 25, 102-113 (1998)], with one another and with a third technique using an opaque edge test device recommended by a new international standard (IEC 62220-1, 2003). The study further aimed to substantiate the influence of various acquisition and processing parameters on the estimated MTF. The slit test device was made of 2 mm thick Pb slabs with a 12.5 {mu}m opening. The translucent edge test device was made of a laminated and polished Pt{sub 0.9}Ir{sub 0.1} alloy foil of 0.1 mm thickness. The opaque edge test device was made of a 2 mm thick W slab. All test devices were imaged on a representative indirect flat-panel digital radiographic system using three published beam qualities: 70 kV with 0.5 mm Cu filtration, 70 kV with 19 mm Al filtration, and 74 kV with 21 mm Al filtration (IEC-RQA5). The latter technique was also evaluated in conjunction with two external beam-limiting apertures (per IEC 62220-1), and with the tube collimator limiting the beam to the same area achieved with the apertures. The presampled MTFs were deduced from the acquired images by Fourier analysis techniques, and the results analyzed for relative values and the influence of impacting parameters. The findings indicated that the measurement technique has a notable impact on the resulting MTF estimate, with estimates from the overall IEC method 4.0%{+-}0.2% lower than that of Dobbins et al. and 0.7%{+-}0.4% higher than that of Samei et al. averaged over the zero to cutoff frequency range. Over the same frequency range, keeping beam quality and limitation constant, the average MTF estimate obtained with the edge techniques differed by up to 5.2%{+-}0.2% from that of the slit, with the opaque edge providing lower MTF estimates at lower frequencies than those obtained with the translucent edge or slit. The beam quality impacted the average estimated MTF by as much as 3.7%{+-}0.9% while the use of beam limiting devices alone increased the average estimated MTF by as much as 7.0%{+-}0.9%. While the slit method is inherently very sensitive to misalignment, both edge techniques were found to tolerate misalignments by as much as 6 cm. The results suggest the use of the opaque edge test device and the tube internal collimator for beam limitation in order to achieve an MTF result most reflective of the overall performance of the imaging system and least susceptible to misalignment and scattered radiation. Careful attention to influencing factors is warranted to achieve accurate results.« less

Intercomparison of methods for image quality characterization. I. Modulation transfer function.

PubMed

Samei, Ehsan; Ranger, Nicole T; Dobbins, James T; Chen, Ying

2006-05-01

The modulation transfer function (MTF) and the noise power spectrum (NPS) are widely recognized as the most relevant metrics of resolution and noise performance in radiographic imaging. These quantities have commonly been measured using various techniques, the specifics of which can have a bearing on the accuracy of the results. As a part of a study aimed at comparing the relative performance of different techniques, in this paper we report on a comparison of two established MTF measurement techniques: one using a slit test device [Dobbins et al., Med. Phys. 22, 1581-1593 (1995)] and another using a translucent edge test device [Samei et al., Med. Phys. 25, 102-113 (1998)], with one another and with a third technique using an opaque edge test device recommended by a new international standard (IEC 62220-1, 2003). The study further aimed to substantiate the influence of various acquisition and processing parameters on the estimated MTF. The slit test device was made of 2 mm thick Pb slabs with a 12.5 microm opening. The translucent edge test device was made of a laminated and polished Pt(0.9)Ir(0.1). alloy foil of 0.1 mm thickness. The opaque edge test device was made of a 2 mm thick W slab. All test devices were imaged on a representative indirect flat-panel digital radiographic system using three published beam qualities: 70 kV with 0.5 mm Cu filtration, 70 kV with 19 mm Al filtration, and 74 kV with 21 mm Al filtration (IEC-RQA5). The latter technique was also evaluated in conjunction with two external beam-limiting apertures (per IEC 62220-1), and with the tube collimator limiting the beam to the same area achieved with the apertures. The presampled MTFs were deduced from the acquired images by Fourier analysis techniques, and the results analyzed for relative values and the influence of impacting parameters. The findings indicated that the measurement technique has a notable impact on the resulting MTF estimate, with estimates from the overall IEC method 4.0% +/- 0.2% lower than that of Dobbins et al. and 0.7% +/- 0.4% higher than that of Samei et al. averaged over the zero to cutoff frequency range. Over the same frequency range, keeping beam quality and limitation constant, the average MTF estimate obtained with the edge techniques differed by up to 5.2% +/- 0.2% from that of the slit, with the opaque edge providing lower MTF estimates at lower frequencies than those obtained with the translucent edge or slit. The beam quality impacted the average estimated MTF by as much as 3.7% +/- 0.9% while the use of beam limiting devices alone increased the average estimated MTF by as much as 7.0% +/- 0.9%. While the slit method is inherently very sensitive to misalignment, both edge techniques were found to tolerate misalignments by as much as 6 cm. The results suggest the use of the opaque edge test device and the tube internal collimator for beam limitation in order to achieve an MTF result most reflective of the overall performance of the imaging system and least susceptible to misalignment and scattered radiation. Careful attention to influencing factors is warranted to achieve accurate results.

Study of Plasma Liner Driven Magnetized Target Fusion Via Advanced Simulations

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

Samulyak, Roman V.; Brookhaven National Lab.; Parks, Paul

The feasibility of the plasma liner driven Magnetized Target Fusion (MTF) via terascale numerical simulations will be assessed. In the MTF concept, a plasma liner, formed by merging of a number (60 or more) of radial, highly supersonic plasma jets, implodes on the target in the form of two compact plasma toroids, and compresses it to conditions of the fusion ignition. By avoiding major difficulties associated with both the traditional laser driven inertial confinement fusion and solid liner driven MTF, the plasma liner driven MTF potentially provides a low-cost and fast R&D path towards the demonstration of practical fusion energy.more » High fidelity numerical simulations of full nonlinear models associated with the plasma liner MTF using state-of-art numerical algorithms and terascale computing are necessary in order to resolve uncertainties and provide guidance for future experiments. At Stony Brook University, we have developed unique computational capabilities that ideally suite the MTF problem. The FronTier code, developed in collaboration with BNL and LANL under DOE funding including SciDAC for the simulation of 3D multi-material hydro and MHD flows, has beenbenchmarked and used for fundamental and engineering problems in energy science applications. We have performed 3D simulations of converging supersonic plasma jets, their merger and the formation of the plasma liner, and a study of the corresponding oblique shock problem. We have studied the implosion of the plasma liner on the magnetized plasma target by resolving Rayleigh-Taylor instabilities in 2D and 3D and other relevant physics and estimate thermodynamic conditions of the target at the moment of maximum compression and the hydrodynamic efficiency of the method.« less

Technical Note: Image filtering to make computer-aided detection robust to image reconstruction kernel choice in lung cancer CT screening

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

Ohkubo, Masaki, E-mail: mook@clg.niigata-u.ac.jp

Purpose: In lung cancer computed tomography (CT) screening, the performance of a computer-aided detection (CAD) system depends on the selection of the image reconstruction kernel. To reduce this dependence on reconstruction kernels, the authors propose a novel application of an image filtering method previously proposed by their group. Methods: The proposed filtering process uses the ratio of modulation transfer functions (MTFs) of two reconstruction kernels as a filtering function in the spatial-frequency domain. This method is referred to as MTF{sub ratio} filtering. Test image data were obtained from CT screening scans of 67 subjects who each had one nodule. Imagesmore » were reconstructed using two kernels: f{sub STD} (for standard lung imaging) and f{sub SHARP} (for sharp edge-enhancement lung imaging). The MTF{sub ratio} filtering was implemented using the MTFs measured for those kernels and was applied to the reconstructed f{sub SHARP} images to obtain images that were similar to the f{sub STD} images. A mean filter and a median filter were applied (separately) for comparison. All reconstructed and filtered images were processed using their prototype CAD system. Results: The MTF{sub ratio} filtered images showed excellent agreement with the f{sub STD} images. The standard deviation for the difference between these images was very small, ∼6.0 Hounsfield units (HU). However, the mean and median filtered images showed larger differences of ∼48.1 and ∼57.9 HU from the f{sub STD} images, respectively. The free-response receiver operating characteristic (FROC) curve for the f{sub SHARP} images indicated poorer performance compared with the FROC curve for the f{sub STD} images. The FROC curve for the MTF{sub ratio} filtered images was equivalent to the curve for the f{sub STD} images. However, this similarity was not achieved by using the mean filter or median filter. Conclusions: The accuracy of MTF{sub ratio} image filtering was verified and the method was demonstrated to be effective for reducing the kernel dependence of CAD performance.« less

32 CFR 728.34 - Care beyond the capabilities of a naval MTF.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 5 2010-07-01 2010-07-01 false Care beyond the capabilities of a naval MTF. 728... Dependents of the Uniformed Services § 728.34 Care beyond the capabilities of a naval MTF. When either during... determination is made that required care or services are beyond the capability of the naval MTF, the provisions...

32 CFR 728.34 - Care beyond the capabilities of a naval MTF.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 5 2011-07-01 2011-07-01 false Care beyond the capabilities of a naval MTF. 728... Dependents of the Uniformed Services § 728.34 Care beyond the capabilities of a naval MTF. When either during... determination is made that required care or services are beyond the capability of the naval MTF, the provisions...

Aerosol scattering and absorption modulation transfer function

NASA Astrophysics Data System (ADS)

Sadot, Dan; Kopeika, Norman S.

1993-08-01

Recent experimental measurements of overall atmospheric modulation transfer function (MTF) indicate significant difference between the turbulence and overall atmospheric MTFs, except often at midday when turbulence is strong. We suggest here a physical explanation for those results which essentially relates to what we call a practical instrumentation-based atmospheric aerosol MTF which is a modification of the classical aerosol MTF theory. It is shown that system field-of-view and dynamic range affect strongly aerosol and overall atmospheric MTFs. It is often necessary to choose between MTF and SNR depending upon dynamic range requirements. Also, a new approach regarding aerosol absorption is presented. It is shown that aerosol-absorbed irradiance is spatial frequency dependent and enhances the degradation in image quality arising from received scattered light. This is most relevant for thermal imaging. An analytically corrected model for the aerosol MTF is presented which is relevant for imaging. An important conclusion is that the aerosol MTF is often the dominant part in the actual overall atmospheric MTF all across the optical spectral region.

Crossover And MTF Characteristics Of A Tabular-Grain X-Ray Film

NASA Astrophysics Data System (ADS)

Huff, K. E.; Wagner, P. W.

1984-08-01

An orthochromatic x-ray film made with tabular silver halide grains has a significantly higher MTF when exposed with green-emitting intensifying screens than do conventional films with similar sensitometric properties. The primary reason for the improved MTF is a decrease in the amount of crossover exposure, i.e., exposure by light that has crossed the support one or more times. Two well-established sensitometric procedures for measuring crossover have been compared. One produces results accurate enough for calculations of MTF relationships. Calculated MTF relationships for tabulargrain and conventional films are compared with measured values.

Evaluation of cassette-based digital radiography detectors using standardized image quality metrics: AAPM TG-150 Draft Image Detector Tests.

PubMed

Li, Guang; Greene, Travis C; Nishino, Thomas K; Willis, Charles E

2016-09-08

The purpose of this study was to evaluate several of the standardized image quality metrics proposed by the American Association of Physics in Medicine (AAPM) Task Group 150. The task group suggested region-of-interest (ROI)-based techniques to measure nonuniformity, minimum signal-to-noise ratio (SNR), number of anomalous pixels, and modulation transfer function (MTF). This study evaluated the effects of ROI size and layout on the image metrics by using four different ROI sets, assessed result uncertainty by repeating measurements, and compared results with two commercially available quality control tools, namely the Carestream DIRECTVIEW Total Quality Tool (TQT) and the GE Healthcare Quality Assurance Process (QAP). Seven Carestream DRX-1C (CsI) detectors on mobile DR systems and four GE FlashPad detectors in radiographic rooms were tested. Images were analyzed using MATLAB software that had been previously validated and reported. Our values for signal and SNR nonuniformity and MTF agree with values published by other investigators. Our results show that ROI size affects nonuniformity and minimum SNR measurements, but not detection of anomalous pixels. Exposure geometry affects all tested image metrics except for the MTF. TG-150 metrics in general agree with the TQT, but agree with the QAP only for local and global signal nonuniformity. The difference in SNR nonuniformity and MTF values between the TG-150 and QAP may be explained by differences in the calculation of noise and acquisition beam quality, respectively. TG-150's SNR nonuniformity metrics are also more sensitive to detector nonuniformity compared to the QAP. Our results suggest that fixed ROI size should be used for consistency because nonuniformity metrics depend on ROI size. Ideally, detector tests should be performed at the exact calibration position. If not feasible, a baseline should be established from the mean of several repeated measurements. Our study indicates that the TG-150 tests can be used as an independent standardized procedure for detector performance assessment. © 2016 The Authors.

Evaluation of cassette‐based digital radiography detectors using standardized image quality metrics: AAPM TG‐150 Draft Image Detector Tests

PubMed Central

Greene, Travis C.; Nishino, Thomas K.; Willis, Charles E.

2016-01-01

The purpose of this study was to evaluate several of the standardized image quality metrics proposed by the American Association of Physics in Medicine (AAPM) Task Group 150. The task group suggested region‐of‐interest (ROI)‐based techniques to measure nonuniformity, minimum signal‐to‐noise ratio (SNR), number of anomalous pixels, and modulation transfer function (MTF). This study evaluated the effects of ROI size and layout on the image metrics by using four different ROI sets, assessed result uncertainty by repeating measurements, and compared results with two commercially available quality control tools, namely the Carestream DIRECTVIEW Total Quality Tool (TQT) and the GE Healthcare Quality Assurance Process (QAP). Seven Carestream DRX‐1C (CsI) detectors on mobile DR systems and four GE FlashPad detectors in radiographic rooms were tested. Images were analyzed using MATLAB software that had been previously validated and reported. Our values for signal and SNR nonuniformity and MTF agree with values published by other investigators. Our results show that ROI size affects nonuniformity and minimum SNR measurements, but not detection of anomalous pixels. Exposure geometry affects all tested image metrics except for the MTF. TG‐150 metrics in general agree with the TQT, but agree with the QAP only for local and global signal nonuniformity. The difference in SNR nonuniformity and MTF values between the TG‐150 and QAP may be explained by differences in the calculation of noise and acquisition beam quality, respectively. TG‐150's SNR nonuniformity metrics are also more sensitive to detector nonuniformity compared to the QAP. Our results suggest that fixed ROI size should be used for consistency because nonuniformity metrics depend on ROI size. Ideally, detector tests should be performed at the exact calibration position. If not feasible, a baseline should be established from the mean of several repeated measurements. Our study indicates that the TG‐150 tests can be used as an independent standardized procedure for detector performance assessment. PACS number(s): 87.57.‐s, 87.57.C PMID:27685102

Detector evaluation of a prototype amorphous selenium-based full field digital mammography system

NASA Astrophysics Data System (ADS)

Jesneck, Jonathan L.; Saunders, Robert S.; Samei, Ehsan; Xia, Jessie Q.; Lo, Joseph Y.

2005-04-01

This study evaluated the physical performance of a selenium-based direct full-field digital mammography prototype detector (Siemens Mammomat NovationDR), including the pixel value vs. exposure linearity, the modulation transfer function (MTF), the normalized noise power spectrum (NNPS), and the detective quantum efficiency (DQE). The current detector is the same model which received an approvable letter from FDA for release to the US market. The results of the current prototype are compared to those of an earlier prototype. Two IEC standard beam qualities (RQA-M2: Mo/Mo, 28 kVp, 2 mm Al; RQA-M4: Mo/Mo, 35 kVp, 2 mm Al) and two additional beam qualities (MW2: W/Rh, 28 kVp, 2 mm Al; MW4: W/Rh, 35 kVp, 2 mm Al) were investigated. To calculate the modulation transfer function (MTF), a 0.1 mm Pt-Ir edge was imaged at each beam quality. Detector pixel values responded linearly against exposure values (R2 0.999). As before, above 6 cycles/mm Mo/Mo MTF was slightly higher along the chest-nipple axis compared to the left-right axis. MTF was comparable to the previously reported prototype, with slightly reduced resolution. The DQE peaks ranged from 0.71 for 3.31 μC/kg (12.83 mR) to 0.4 for 0.48 μC/kg (1.86 mR) at 1.75 cycles/mm for Mo/Mo at 28 kVp. The DQE range for W/Rh at 28 kVP was 0.81 at 2.03 μC/kg (7.87 mR) to 0.50 at 0.50 μC/kg (1.94 mR) at 1 cycle/mm. NNPS tended to increase with greater exposures, while all exposures had a significant low-frequency component. Bloom and detector edge artifacts observed previously were no longer present in this prototype. The new detector shows marked noise improvement, with slightly reduced resolution. There remain artifacts due to imperfect gain calibration, but at a reduced magnitude compared to a prototype detector.

Similar Response Patterns to 5%Topical Minoxidil Foam in Frontal and Vertex Scalp of Men with Androgenetic Alopecia: A Microarray Analysis

PubMed Central

Mirmirani, P.; Consolo, M.; Oyetakin-White, P.; Baron, E.; Leahy, P.; Karnik, P.

2014-01-01

Summary Background There are regional variations in scalp hair miniaturization seen in androgenetic alopecia (AGA). Use of topical minoxidil can lead to reversal of miniaturization in the vertex scalp. However, its effects on other scalp regions are less well studied. Methods A placebo controlled double-blinded prospective pilot study of minoxidil topical foam 5% (MTF) vs placebo was conducted in sixteen healthy men ages 18-49 with Hamilton-Norwood type IV-V thinning. The subjects were asked to apply the treatment (active drug or placebo) to the scalp twice daily for eight weeks. Stereotactic scalp photographs were taken at the baseline and final visits to monitor global hair growth. Scalp biopsies were done at the leading edge of hair loss from the frontal and vertex scalp before and after treatment with MTF and placebo and microarray analysis was done using the Affymetrix GeneChip HG U133 Plus 2.0. Results Global stereotactic photographs showed that MTF induced hair growth in both the frontal and vertex scalp of AGA patients. Regional differences in gene expression profiles were observed before treatment. However, MTF treatment induced the expression of hair keratin associated genes and decreased the expression of epidermal differentiation complex (EDC) and inflammatory genes in both scalp regions. Conclusions These data suggest that MTF is effective in the treatment of both the frontal and vertex scalp of AGA patients. PMID:25204361

Genetic variation in metallothionein and metal-regulatory transcription factor 1 in relation to urinary cadmium, copper, and zinc

PubMed Central

Adams, Scott V.; Barrick, Brian; Freney, Emily P.; Shafer, Martin M.; Makar, Karen; Song, Xiaoling; Lampe, Johanna; Vilchis, Hugo; Ulery, April; Newcomb, Polly A.

2015-01-01

Background Metallothionein (MT) proteins play critical roles in the physiological handling of both essential (Cu and Zn) and toxic (Cd) metals. MT expression is regulated by metal-regulatory transcription factor 1 (MTF1). Hence, genetic variation in the MT gene family and MTF1 might therefore influence excretion of these metals. Methods 321 women were recruited in Seattle, WA and Las Cruces, NM and provided demographic information, urine samples for measurement of metal concentrations by mass spectrometry and creatinine, and blood or saliva for extraction of DNA. Forty-one single nucleotide polymorphisms (SNPs) within the MTF1 gene region and the region of chromosome 16 encoding the MT gene family were selected for genotyping in addition to an ancestry informative marker panel. Linear regression was used to estimate the association of SNPs with urinary Cd, Cu, and Zn, adjusted for age, urinary creatinine, smoking history, study site, and ancestry. Results Minor alleles of rs28366003 and rs10636 near the MT2A gene were associated with lower urinary Cd, Cu, and Zn. Minor alleles of rs8044719 and rs1599823, near MT1A and MT1B, were associated with lower urinary Cd and Zn, respectively. Minor alleles of rs4653329 in MTF1 was associated with lower urinary Cd. Conclusions These results suggest that genetic variation in the MT gene region and MTF1 influences urinary Cd, Cu, and Zn excretion. PMID:26529669

Image quality of the cat eye measured during retinal ganglion cell experiments.

PubMed

Bonds, A B; Enroth-Cugell, C; Pinto, L H

1972-01-01

1. The modulation transfer function (MTF) of the dioptrics of fifteen cat eyes was determined. The aerial image, formed by the eye of a standard object (a 0.5-1.0 degrees annulus), was photographed. The transmission of the film negative was measured with a scanning microdensitometer to yield the light distribution within the aerial image. Correcting for the double passage, this experimentally determined light distribution and the known object light distribution were used to obtain the MTF, applying Fourier methods. Each MTF was used to calculate the light distribution within the retinal image of stimuli of various geometry used in experiments on retinal ganglion cells in the same eye.2. When the eye was equipped with an artificial pupil of the same size as that used in the neurophysiological experiments (4.0-4.8 mm diam.) the MTF had fallen to 0.5 at 2.43 c/deg. When the pupil was removed the MTF had fallen to 0.5 at a much lower spatial frequency (1.0 c/deg). This shows that even when one uses an artificial pupil too large to provide optimal image quality there is a vast improvement over using no pupil.3. These image quality measurements were prompted by the need to know the actual stimulus image in experiments on the functional organization of the receptive field, a need exemplified in this paper by a few specific physiological results. The full neurophysiological results appear in the next two papers.

Bulk flow in the combined 2MTF and 6dFGSv surveys

NASA Astrophysics Data System (ADS)

Qin, Fei; Howlett, Cullan; Staveley-Smith, Lister; Hong, Tao

2018-07-01

We create a combined sample of 10 904 late- and early-type galaxies from the 2MTF and 6dFGSv surveys in order to accurately measure bulk flow in the local Universe. Galaxies and groups of galaxies common between the two surveys are used to verify that the difference in zero-points is <0.02 dex. We introduce a maximum likelihood estimator (ηMLE) for bulk flow measurements that allows for more accurate measurement in the presence of non-Gaussian measurement errors. To calibrate out residual biases due to the subtle interaction of selection effects, Malmquist bias and anisotropic sky distribution, the estimator is tested on mock catalogues generated from 16 independent large-scale GiggleZ and SURFS simulations. The bulk flow of the local Universe using the combined data set, corresponding to a scale size of 40 h-1 Mpc, is 288 ± 24 km s-1 in the direction (l, b) = (296 ± 6°, 21 ± 5°). This is the most accurate bulk flow measurement to date, and the amplitude of the flow is consistent with the Λ cold dark matter expectation for similar size scales.

Bulk flow in the combined 2MTF and 6dFGSv surveys

NASA Astrophysics Data System (ADS)

Qin, Fei; Howlett, Cullan; Staveley-Smith, Lister; Hong, Tao

2018-04-01

We create a combined sample of 10,904 late and early-type galaxies from the 2MTF and 6dFGSv surveys in order to accurately measure bulk flow in the local Universe. Galaxies and groups of galaxies common between the two surveys are used to verify that the difference in zero-points is <0.02 dex. We introduce a new maximum likelihood estimator (ηMLE) for bulk flow measurements which allows for more accurate measurement in the presence non-Gaussian measurement errors. To calibrate out residual biases due to the subtle interaction of selection effects, Malmquist bias and anisotropic sky distribution, the estimator is tested on mock catalogues generated from 16 independent large-scale GiggleZ and SURFS simulations. The bulk flow of the local Universe using the combined data set, corresponding to a scale size of 40 h-1 Mpc, is 288 ± 24 km s-1 in the direction (l, b) = (296 ± 6°, 21 ± 5°). This is the most accurate bulk flow measurement to date, and the amplitude of the flow is consistent with the ΛCDM expectation for similar size scales.

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

Melnyk, Roman; DiBianca, Frank A.

The detector presampling modulation transfer function (MTF) of a 576-channel variable resolution x-ray (VRX) computed tomography (CT) scanner was evaluated in this study. The scanner employs a VRX detector, which provides increased spatial resolution by matching the scanner's field of view (FOV) to the size of an object being imaged. Because spatial resolution is the parameter the scanner promises to improve, the evaluation of this resolution is important. The scanner's pre-reconstruction spatial resolution, represented by the detector presampling MTF, was evaluated using both modeling (Monte Carlo simulation) and measurement (the moving slit method). The theoretical results show the increase inmore » the cutoff frequency of the detector presampling MTF from 1.39 to 43.38 cycles/mm as the FOV of the VRX CT scanner decreases from 32 to 1 cm. The experimental results are in reasonable agreement with the theoretical data. Some discrepancies between the measured and the modeled detector presampling MTFs can be explained by the limitations of the model. At small FOVs (1-8 cm), the MTF measurements were limited by the size of the focal spot. The obtained results are important for further development of the VRX CT scanner.« less

Influence of Iterative Reconstruction Algorithms on PET Image Resolution

NASA Astrophysics Data System (ADS)

Karpetas, G. E.; Michail, C. M.; Fountos, G. P.; Valais, I. G.; Nikolopoulos, D.; Kandarakis, I. S.; Panayiotakis, G. S.

2015-09-01

The aim of the present study was to assess image quality of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction. The simulated PET scanner was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution (1MBq). Image quality was assessed in terms of the modulation transfer function (MTF). MTF curves were estimated from transverse reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL, the ordered subsets separable paraboloidal surrogate (OSSPS), the median root prior (MRP) and OSMAPOSL with quadratic prior, algorithms. OSMAPOSL reconstruction was assessed by using fixed subsets and various iterations, as well as by using various beta (hyper) parameter values. MTF values were found to increase with increasing iterations. MTF also improves by using lower beta values. The simulated PET evaluation method, based on the TLC plane source, can be useful in the resolution assessment of PET scanners.

Brain Activation in Response to Visually Evoked Sexual Arousal in Male-to-Female Transsexuals: 3.0 Tesla Functional Magnetic Resonance Imaging

PubMed Central

Oh, Seok-Kyun; Kim, Gwang-Won; Yang, Jong-Chul; Kim, Seok-Kwun; Kang, Heoung-Keun

2012-01-01

Objective This study used functional magnetic resonance imaging (fMRI) to contrast the differential brain activation patterns in response to visual stimulation with both male and female erotic nude pictures in male-to-female (MTF) transsexuals who underwent a sex reassignment surgery. Materials and Methods A total of nine healthy MTF transsexuals after a sex reassignment surgery underwent fMRI on a 3.0 Tesla MR Scanner. The brain activation patterns were induced by visual stimulation with both male and female erotic nude pictures. Results The sex hormone levels of the postoperative MTF transsexuals were in the normal range of healthy heterosexual females. The brain areas, which were activated by viewing male nude pictures when compared with viewing female nude pictures, included predominantly the cerebellum, hippocampus, putamen, anterior cingulate gyrus, head of caudate nucleus, amygdala, midbrain, thalamus, insula, and body of caudate nucleus. On the other hand, brain activation induced by viewing female nude pictures was predominantly observed in the hypothalamus and the septal area. Conclusion Our findings suggest that distinct brain activation patterns associated with visual sexual arousal in postoperative MTF transsexuals reflect their sexual orientation to males. PMID:22563262

Optical bench performance of a novel trifocal intraocular lens compared with a multifocal intraocular lens

PubMed Central

Lee, Shinwook; Choi, Myoung; Xu, Zaiwei; Zhao, Zeyu; Alexander, Elsinore; Liu, Yueai

2016-01-01

Purpose The purpose of this study is to compare the optical characteristics of the novel PanOptix presbyopia-correcting trifocal intraocular lens (IOL) and the multifocal ReSTOR +3.0 D IOL, through in vitro bench investigations. Methods The optical characteristics of AcrySof® IQ PanOptix™ (PanOptix) and AcrySof® IQ ReSTOR +3.0 D (ReSTOR +3.0 D) IOLs were evaluated by through-focus Badal images, simulated headlight images, and modulation transfer function (MTF) measurements which determine resolution, photic phenomena, and image quality. Through-focus Badal images of an Early Treatment of Diabetic Retinopathy Study chart were recorded at both photopic and mesopic pupil sizes. Simulated headlight images were taken on an MTF bench with a 50-μm pinhole target and a 5.0 mm pupil at the distance focus of the IOL. MTF curves were measured with a 3.0 mm pupil, and spatial frequencies equivalent to 20/40 and 20/20 visual acuities were recorded to illustrate the through-focus MTF curves. Far-, intermediate-, and near-focus MTF values were obtained. Results Bench Badal image testing and MTF measurements showed that PanOptix has a near focus at a distance of 42 cm and an additional intermediate focus at a distance of about 60 cm. The near focus for ReSTOR +3.0 D is at 45 cm. PanOptix and ReSTOR +3.0 D have comparable photopic distances and near MTF values. Additionally, PanOptix provided a substantial continuous range of vision from distance to intermediate and to near compared with ReSTOR +3.0 D. The halo propensity for PanOptix was slightly higher than that for ReSTOR +3.0 D. Conclusion Laboratory-based in vitro simulations showed that PanOptix trifocal IOL has comparable resolution and image quality performance in distance and near foci compared with ReSTOR +3.0 D IOL. PanOptix showed better resolution and image quality performance at the intermediate focus than ReSTOR +3.0 D IOL. PMID:27330273

Correlation between k-space sampling pattern and MTF in compressed sensing MRSI.

PubMed

Heikal, A A; Wachowicz, K; Fallone, B G

2016-10-01

To investigate the relationship between the k-space sampling patterns used for compressed sensing MR spectroscopic imaging (CS-MRSI) and the modulation transfer function (MTF) of the metabolite maps. This relationship may allow the desired frequency content of the metabolite maps to be quantitatively tailored when designing an undersampling pattern. Simulations of a phantom were used to calculate the MTF of Nyquist sampled (NS) 32 × 32 MRSI, and four-times undersampled CS-MRSI reconstructions. The dependence of the CS-MTF on the k-space sampling pattern was evaluated for three sets of k-space sampling patterns generated using different probability distribution functions (PDFs). CS-MTFs were also evaluated for three more sets of patterns generated using a modified algorithm where the sampling ratios are constrained to adhere to PDFs. Strong visual correlation as well as high R 2 was found between the MTF of CS-MRSI and the product of the frequency-dependant sampling ratio and the NS 32 × 32 MTF. Also, PDF-constrained sampling patterns led to higher reproducibility of the CS-MTF, and stronger correlations to the above-mentioned product. The relationship established in this work provides the user with a theoretical solution for the MTF of CS MRSI that is both predictable and customizable to the user's needs.

Optical aberrations in underwater photogrammetry with flat and hemispherical dome ports

NASA Astrophysics Data System (ADS)

Menna, Fabio; Nocerino, Erica; Remondino, Fabio

2017-06-01

The paper analyses differences between dome and flat port housings used for underwater photogrammetry. The underwater environment negatively affects image quality and 3D reconstructions, but this influence on photogrammetric measurements, so far, has not been addressed properly in the literature. In this work, motivations behind the need for systematic underwater calibrations are provided, then experimental tests using a specifically designed photogrammetric modular test object in laboratory and at sea are reported. The experiments are carried out using a Nikon D750 24 Mpx DSLR camera with a 24 mm f2.8 AF/D lens coupled with a NIMAR NI3D750ZM housing, equipped first with a dome and, successively, with a flat port. To quantify the degradation of image quality, MTF measurements are carried out, then the outcomes of self-calibrating bundle adjustment calibrations are shown and commented. Optical phenomena like field curvature as well as chromatic aberration and astigmatism are analysed and their implications on the degradation of image quality is factored in the bundle adjustment through a different weighting of 2D image observations.

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

Scaduto, DA; Hu, Y-H; Zhao, W

Purpose: Spatial resolution in digital breast tomosynthesis (DBT) is affected by inherent/binned detector resolution, oblique entry of x-rays, and focal spot size/motion; the limited angular range further limits spatial resolution in the depth-direction. While DBT is being widely adopted clinically, imaging performance metrics and quality control protocols have not been standardized. AAPM Task Group 245 on Tomosynthesis Quality Control has been formed to address this deficiency. Methods: Methods of measuring spatial resolution are evaluated using two prototype quality control phantoms for DBT. Spatial resolution in the detector plane is measured in projection and reconstruction domains using edge-spread function (ESF), point-spreadmore » function (PSF) and modulation transfer function (MTF). Spatial resolution in the depth-direction and effective slice thickness are measured in the reconstruction domain using slice sensitivity profile (SSP) and artifact spread function (ASF). An oversampled PSF in the depth-direction is measured using a 50 µm angulated tungsten wire, from which the MTF is computed. Object-dependent PSF is derived and compared with ASF. Sensitivity of these measurements to phantom positioning, imaging conditions and reconstruction algorithms is evaluated. Results are compared from systems of varying acquisition geometry (9–25 projections over 15–60°). Dependence of measurements on feature size is investigated. Results: Measurements of spatial resolution using PSF and LSF are shown to depend on feature size; depth-direction spatial resolution measurements are shown to similarly depend on feature size for ASF, though deconvolution with an object function removes feature size-dependence. A slanted wire may be used to measure oversampled PSFs, from which MTFs may be computed for both in-plane and depth-direction resolution. Conclusion: Spatial resolution measured using PSF is object-independent with sufficiently small object; MTF is object-independent. Depth-direction spatial resolution may be measured directly using MTF or indirectly using ASF or SSP as surrogate measurements. While MTF is object-independent, it is invalid for nonlinear reconstructions.« less

Edge method for on-orbit defocus assessment.

PubMed

Viallefont-Robinet, Françoise

2010-09-27

In the earth observation domain, two classes of sensors may be distinguished: a class for which sensor performances are driven by radiometric accuracy of the images and a class for which sensor performances are driven by spatial resolution. In this latter case, as spatial resolution depends on the triplet constituted by the Ground Sampling Distance (GSD), Modulation Transfer Function (MTF), and Signal to Noise Ratio (SNR), refocusing, acting as an MTF improvement, is very important. Refocusing is not difficult by itself as far as the on-board mechanism is reliable. The difficulty is on the defocus assessment side. Some methods such as those used for the SPOT family rely on the ability of the satellite to image the same landscape with two focusing positions. This can be done with a bi-sensor configuration, with adequate focal plane, or with the satellite agility. A new generation of refocusing mechanism will be taken aboard Pleiades. As the speed of this mechanism will be much slower than the speed of the older generation, it won't be possible, despite the agility of the satellite, to image the same landscape with two focusing positions on the same orbit. That's why methods relying on MTF measurement with edge method have been studied. This paper describes the methods and the work done to assess the defocus measurement accuracy in the Pleiades context.

Measurement of cone beam CT coincidence with megavoltage isocentre and image sharpness using the QUASAR Penta-Guide phantom.

PubMed

Sykes, J R; Lindsay, R; Dean, C J; Brettle, D S; Magee, D R; Thwaites, D I

2008-10-07

For image-guided radiotherapy (IGRT) systems based on cone beam CT (CBCT) integrated into a linear accelerator, the reproducible alignment of imager to x-ray source is critical to the registration of both the x-ray-volumetric image with the megavoltage (MV) beam isocentre and image sharpness. An enhanced method of determining the CBCT to MV isocentre alignment using the QUASAR Penta-Guide phantom was developed which improved both precision and accuracy. This was benchmarked against our existing method which used software and a ball-bearing (BB) phantom provided by Elekta. Additionally, a method of measuring an image sharpness metric (MTF(50)) from the edge response function of a spherical air cavity within the Penta-Guide phantom was developed and its sensitivity was tested by simulating misalignments of the kV imager. Reproducibility testing of the enhanced Penta-Guide method demonstrated a systematic error of <0.2 mm when compared to the BB method with near equivalent random error (s=0.15 mm). The mean MTF(50) for five measurements was 0.278+/-0.004 lp mm(-1) with no applied misalignment. Simulated misalignments exhibited a clear peak in the MTF(50) enabling misalignments greater than 0.4 mm to be detected. The Penta-Guide phantom can be used to precisely measure CBCT-MV coincidence and image sharpness on CBCT-IGRT systems.

A Study of the Efficacy of the Five Phase Recovery Process as a Method of Maximizing Reimbursements under the Third Party Collection Program

DTIC Science & Technology

1991-07-01

MTF, or establishing a standard CGR should be done cautiously since health care is a local phenomenon and a number of factors influence (1) the...goals should be formulated locally. That is, each MTF must identify for itself those beneficiaries in its catchment area with billable insurance who...this, managers must know the work they supervise. 8. Drive out fear. Employees should not be afraid to point out problems for fear of argument or being

A plasmid containing the human metallothionein II gene can function as an antibody-assisted electrophoretic biosensor for heavy metals.

PubMed

Wooten, Dennis C; Starr, Clarise R; Lyon, Wanda J

2016-01-01

Different forms of heavy metals affect biochemical systems in characteristic ways that cannot be detected with typical metal analysis methods like atomic absorption spectrometry. Further, using living systems to analyze interaction of heavy metals with biochemical systems can be laborious and unreliable. To generate a reliable easy-to-use biologically-based biosensor system, the entire human metallothionein-II (MT-II) gene was incorporated into a plasmid (pUC57-MT) easily replicated in Escherichia coli. In this system, a commercial polyclonal antibody raised against human metal-responsive transcription factor-1 protein (MTF-1 protein) could modify the electrophoretic migration patterns (i.e. cause specific decreases in agarose gel electrophoretic mobility) of the plasmid in the presence or absence of heavy metals other than zinc (Zn). In the study here, heavy metals, MTF-1 protein, and polyclonal anti-MTF-1 antibody were used to assess pUC57-MT plasmid antibody-assisted electrophoretic mobility. Anti-MTF-1 antibody bound both MTF-1 protein and pUC57-MT plasmid in a non-competitive fashion such that it could be used to differentiate specific heavy metal binding. The results showed that antibody-inhibited plasmid migration was heavy metal level-dependent. Zinc caused a unique mobility shift pattern opposite to that of other metals tested, i.e. Zn blocked the antibody ability to inhibit plasmid migration, despite a greatly increased affinity for DNA by the antibody when Zn was present. The Zn effect was reversed/modified by adding MTF-1 protein. Additionally, antibody inhibition of plasmid mobility was resistant to heat pre-treatment and trypsinization, indicating absence of residual DNA extraction-resistant bacterial DNA binding proteins. DNA binding by anti-DNA antibodies may be commonly enhanced by xenobiotic heavy metals and elevated levels of Zn, thus making them potentially effective tools for assessment of heavy metal bioavailability in aqueous solutions and fluid obtained from metal implant sites.

Contributions to the Characterization and Mitigation of Rotorcraft Brownout

NASA Astrophysics Data System (ADS)

Tritschler, John Kirwin

Rotorcraft brownout, the condition in which the flow field of a rotorcraft mobilizes sediment from the ground to generate a cloud that obscures the pilot's field of view, continues to be a significant hazard to civil and military rotorcraft operations. This dissertation presents methodologies for: (i) the systematic mitigation of rotorcraft brownout through operational and design strategies and (ii) the quantitative characterization of the visual degradation caused by a brownout cloud. In Part I of the dissertation, brownout mitigation strategies are developed through simulation-based brownout studies that are mathematically formulated within a numerical optimization framework. Two optimization studies are presented. The first study involves the determination of approach-to-landing maneuvers that result in reduced brownout severity. The second study presents a potential methodology for the design of helicopter rotors with improved brownout characteristics. The results of both studies indicate that the fundamental mechanisms underlying brownout mitigation are aerodynamic in nature, and the evolution of a ground vortex ahead of the rotor disk is seen to be a key element in the development of a brownout cloud. In Part II of the dissertation, brownout cloud characterizations are based upon the Modulation Transfer Function (MTF), a metric commonly used in the optics community for the characterization of imaging systems. The use of the MTF in experimentation is examined first, and the application of MTF calculation and interpretation methods to actual flight test data is described. The potential for predicting the MTF from numerical simulations is examined second, and an initial methodology is presented for the prediction of the MTF of a brownout cloud. Results from the experimental and analytical studies rigorously quantify the intuitively-known facts that the visual degradation caused by brownout is a space and time-dependent phenomenon, and that high spatial frequency features, i.e., fine-grained detail, are obscured before low spatial frequency features, i.e., large objects. As such, the MTF is a metric that is amenable to Handling Qualities (HQ) analyses.

Metformin as a prophylactic treatment of gestational diabetes in pregnant patients with pregestational insulin resistance: A randomized study.

PubMed

Valdés, Enrique; Sepúlveda-Martínez, Alvaro; Candia, Paula; Abusada, Nancy; Orellana, Rodrigo; Manukian, Bárbara; Cuellar, Eduardo

2018-01-01

We aimed to assess the use of metformin (MTF) in the prevention of gestational diabetes mellitus (GDM) in patients with pregestational insulin resistance (PIR). A double blind, multicenter, randomized trial was carried out in patients with a history of PIR and pregestational MTF treatment. Groups were allocated either to MTF 1700 mg/day or placebo. Patients were recruited between 12 +0 and 15 +6  gestational weeks, and treatment was extended until week 36. A multiple logistic regression analysis was applied to determine the relation between the use of metformin and the development of GDM. One hundred and forty one patients were randomized (68 patients in the MTF group and 73 in the placebo group). A total of 30 patients withdrew from the study during follow-up. Administration of MTF was not associated with a decrease in the incidence of GDM as compared to placebo (37.5% vs 25.4%, respectively; P = 0.2). Moreover, MTF administration was associated with a significant increase in drug intolerance as compared to placebo (14.3% vs 1.8%, respectively; P = 0.02). The use of MTF is not effective in prevention of GDM in populations with PIR. The use of MTF shows a significantly higher frequency of drug intolerance than placebo. © 2017 Japan Society of Obstetrics and Gynecology.

Sociodemographic Study of Danish Individuals Diagnosed with Transsexualism

PubMed Central

Simonsen, Rikke; Hald, Gert Martin; Giraldi, Annamaria; Kristensen, Ellids

2015-01-01

Introduction Male-to-female (MtF) and female-to-male (FtM) individuals with transsexualism (International Classification of Diseases-10) may differ in core clinical and sociodemographic variables such as age, sexual orientation, marriage and parenthood, school, educational level, and employment. Assessing and understanding the implication of such differences may be a key to developing appropriate and effective treatment and intervention strategies for this group. However, research in the area remains sparse and is often on small populations, making the generalization of results from current studies on individuals diagnosed with transsexualism difficult. Aims (i) To describe and assess key sociodemographic and treatment-related differences between MtF and FtM individuals in a Danish population of individuals diagnosed with transsexualism; (ii) to assess possible implications of such difference, if any, for clinical treatment initiatives for individuals diagnosed with transsexualism. Methods Follow-up of 108 individuals who had permission to undergo sex reassignment surgery (SRS, meaning castration and genital plastic surgery) over a 30-year period from 1978 to 2008 through the Gender Identity Unit in Copenhagen, Denmark. The individuals were identified through Social Security numbers. Clinical and sociodemographic data from medical records were collected. Results The sex ratio was 1.16:1 (MtF : FtM). Mean age at first referral was 26.9 (standard deviation [SD] 8.8) years for FtM and 30.2 (SD 9.7) for MtF individuals. Compared with MtF, FtM had a significantly lower onset age (before 12 years of age) and lower age when permission for SRS was granted. Further, FtM individuals were significantly more often gynephilic (sexually attracted to females) during research period and less likely to start self-initiated hormonal sex reassignment (SR) (treatment with cross-sex hormones). The MtF and FtM groups did not differ in years of school, educational level, employment, or engagement in marriage and cohabitation. Conclusions As approximately half of MtF started cross-sex hormonal SR without attending a gender unit, future treatment needs to focus on this group of MtF individuals in order to accommodate the medical risks of self-initiated hormonal treatment.Earlier intervention with adolescents appears necessary since three-quarters of FtM individuals before age 12 had problems with their assigned sex. For both MtF and FtM, we found problems in areas of school, education, and employment and recommend further help in these core areas. PMID:26185676

Towards the Experimental Assessment of the DQE in SPECT Scanners

NASA Astrophysics Data System (ADS)

Fountos, G. P.; Michail, C. M.

2017-11-01

The purpose of this work was to introduce the Detective Quantum Efficiency (DQE) in single photon emission computed tomography (SPECT) systems using a flood source. A Tc-99m-based flood source (Eγ = 140 keV) consisting of a radiopharmaceutical solution of dithiothreitol (DTT, 10-3 M)/Tc-99m(III)-DMSA, 40 mCi/40 ml bound to the grains of an Agfa MammoRay HDR Medical X-ray film) was prepared in laboratory. The source was placed between two PMMA blocks and images were obtained by using the brain tomographic acquisition protocol (DatScan-brain). The Modulation Transfer Function (MTF) was evaluated using the Iterative 2D algorithm. All imaging experiments were performed in a Siemens e-Cam gamma camera. The Normalized Noise Power spectra (NNPS) were obtained from the sagittal views of the source. The higher MTF values were obtained for the Flash Iterative 2D with 24 iterations and 20 subsets. The noise levels of the SPECT reconstructed images, in terms of the NNPS, were found to increase as the number of iterations increase. The behavior of the DQE was influenced by both MTF and NNPS. As the number of iterations was increased, higher MTF values were obtained, however with a parallel, increase of magnitude in image noise, as depicted from the NNPS results. DQE values, which were influenced by both MTF and NNPS, were found higher when the number of iterations results in resolution saturation. The method presented here is novel and easy to implement, requiring materials commonly found in clinical practice and can be useful in the quality control of SPECT scanners.

Performance characteristics of a Kodak computed radiography system.

PubMed

Bradford, C D; Peppler, W W; Dobbins, J T

1999-01-01

The performance characteristics of a photostimulable phosphor based computed radiographic (CR) system were studied. The modulation transfer function (MTF), noise power spectra (NPS), and detective quantum efficiency (DQE) of the Kodak Digital Science computed radiography (CR) system (Eastman Kodak Co.-model 400) were measured and compared to previously published results of a Fuji based CR system (Philips Medical Systems-PCR model 7000). To maximize comparability, the same measurement techniques and analysis methods were used. The DQE at four exposure levels (30, 3, 0.3, 0.03 mR) and two plate types (standard and high resolution) were calculated from the NPS and MTF measurements. The NPS was determined from two-dimensional Fourier analysis of uniformly exposed plates. The presampling MTF was determined from the Fourier transform (FT) of the system's finely sampled line spread function (LSF) as produced by a narrow slit. A comparison of the slit type ("beveled edge" versus "straight edge") and its effect on the resulting MTF measurements was also performed. The results show that both systems are comparable in resolution performance. The noise power studies indicated a higher level of noise for the Kodak images (approximately 20% at the low exposure levels and 40%-70% at higher exposure levels). Within the clinically relevant exposure range (0.3-3 mR), the resulting DQE for the Kodak plates ranged between 20%-50% lower than for the corresponding Fuji plates. Measurements of the presampling MTF with the two slit types have shown that a correction factor can be applied to compensate for transmission through the relief edges.

Image quality of the cat eye measured during retinal ganglion cell experiments

PubMed Central

Bonds, A. B.; Enroth-Cugell, Christina; Pinto, L. H.

1972-01-01

1. The modulation transfer function (MTF) of the dioptrics of fifteen cat eyes was determined. The aerial image, formed by the eye of a standard object (a 0·5-1·0° annulus), was photographed. The transmission of the film negative was measured with a scanning microdensitometer to yield the light distribution within the aerial image. Correcting for the double passage, this experimentally determined light distribution and the known object light distribution were used to obtain the MTF, applying Fourier methods. Each MTF was used to calculate the light distribution within the retinal image of stimuli of various geometry used in experiments on retinal ganglion cells in the same eye. 2. When the eye was equipped with an artificial pupil of the same size as that used in the neurophysiological experiments (4·0-4·8 mm diam.) the MTF had fallen to 0·5 at 2·43 c/deg. When the pupil was removed the MTF had fallen to 0·5 at a much lower spatial frequency (1·0 c/deg). This shows that even when one uses an artificial pupil too large to provide optimal image quality there is a vast improvement over using no pupil. 3. These image quality measurements were prompted by the need to know the actual stimulus image in experiments on the functional organization of the receptive field, a need exemplified in this paper by a few specific physiological results. The full neurophysiological results appear in the next two papers. ImagesFig. 3Fig. 4 PMID:5014105

Small pixel cross-talk MTF and its impact on MWIR sensor performance

NASA Astrophysics Data System (ADS)

Goss, Tristan M.; Willers, Cornelius J.

2017-05-01

As pixel sizes reduce in the development of modern High Definition (HD) Mid Wave Infrared (MWIR) detectors the interpixel cross-talk becomes increasingly difficult to regulate. The diffusion lengths required to achieve the quantum efficiency and sensitivity of MWIR detectors are typically longer than the pixel pitch dimension, and the probability of inter-pixel cross-talk increases as the pixel pitch/diffusion length fraction decreases. Inter-pixel cross-talk is most conveniently quantified by the focal plane array sampling Modulation Transfer Function (MTF). Cross-talk MTF will reduce the ideal sinc square pixel MTF that is commonly used when modelling sensor performance. However, cross-talk MTF data is not always readily available from detector suppliers, and since the origins of inter-pixel cross-talk are uniquely device and manufacturing process specific, no generic MTF models appear to satisfy the needs of the sensor designers and analysts. In this paper cross-talk MTF data has been collected from recent publications and the development for a generic cross-talk MTF model to fit this data is investigated. The resulting cross-talk MTF model is then included in a MWIR sensor model and the impact on sensor performance is evaluated in terms of the National Imagery Interoperability Rating Scale's (NIIRS) General Image Quality Equation (GIQE) metric for a range of fnumber/ detector pitch Fλ/d configurations and operating environments. By applying non-linear boost transfer functions in the signal processing chain, the contrast losses due to cross-talk may be compensated for. Boost transfer functions, however, also reduce the signal to noise ratio of the sensor. In this paper boost function limits are investigated and included in the sensor performance assessments.

Sinusoidal modulation analysis for optical system MTF measurements.

PubMed

Boone, J M; Yu, T; Seibert, J A

1996-12-01

The modulation transfer function (MTF) is a commonly used metric for defining the spatial resolution characteristics of imaging systems. While the MTF is defined in terms of how an imaging system demodulates the amplitude of a sinusoidal input, this approach has not been in general use to measure MTFs in the medical imaging community because producing sinusoidal x-ray patterns is technically difficult. However, for optical systems such as charge coupled devices (CCD), which are rapidly becoming a part of many medical digital imaging systems, the direct measurement of modulation at discrete spatial frequencies using a sinusoidal test pattern is practical. A commercially available optical test pattern containing spatial frequencies ranging from 0.375 cycles/mm to 80 cycles/mm was sued to determine the MRF of a CCD-based optical system. These results were compared with the angulated slit method of Fujita [H. Fujita, D. Tsia, T. Itoh, K. Doi, J. Morishita, K. Ueda, and A. Ohtsuka, "A simple method for determining the modulation transfer function in digital radiography," IEEE Trans. Medical Imaging 11, 34-39 (1992)]. The use of a semiautomated profiled iterated reconstruction technique (PIRT) is introduced, where the shift factor between successive pixel rows (due to angulation) is optimized iteratively by least-squares error analysis rather than by hand measurement of the slit angle. PIRT was used to find the slit angle for the Fujita technique and to find the sine-pattern angle for the sine-pattern technique. Computer simulation of PIRT for the case of the slit image (a line spread function) demonstrated that it produced a more accurate angle determination than "hand" measurement, and there is a significant difference between the errors in the two techniques (Wilcoxon Signed Rank Test, p < 0.001). The sine-pattern method and the Fujita slit method produced comparable MTF curves for the CCD camera evaluated.

Design, assembly, and metrology of an oil-immersion microscope objective with long working distance

NASA Astrophysics Data System (ADS)

Peng, Wei-Jei; Lin, Wen-Lung; Kuo, Hui-Jean; Ho, Cheng-Fang; Hsu, Wei-Yao

2016-10-01

The design, tolerance sensitivity reduction, assembly, and optical bench test for an oil-immersion microscope objective with long working distance employed in a lattice light-sheet microscope is presented in this paper. In this application, the orthogonal excitation and detection objectives are dipped in an oil medium. The excitation objective focuses the incident laser beam to generate fluorescence on specimen for collecting by detection objective. The excitation objective is custom-designed to meet the requirement specification such as oil-immersion, the long working distance, and numerical aperture (NA) of 0.5, etc. To produce an acceptable point spread function (PSF) for effective excitation, the performance of the objective needs to be close to diffraction limit. Because the tolerance of the modulation transfer function (MTF) is more and more sensitive at higher spatial frequency, it is extremely critical to keep the performance after manufacture. Consequently, an insensitive optical design is very important for relaxing tolerance. We compare the design with and without tolerance sensitivity reduction, and the as-built MTF shows the result. Furthermore, the method for sensitivity reduction is presented. The opto-mechanical design and assembly method are also discussed. Eventually, the objective with five spherical lenses was fabricated. In optical bench test, the depth of the oil is sensitive to MTF, and it leads to the complicated adjustment. For solving this issue, we made an index-matching lens to replace oil for measurement easily. Finally, the measured MTF of the excitation objective can accomplish the requirement specification and successfully employed in a lattice light-sheet microscope.

Comparison of edge analysis techniques for the determination of the MTF of digital radiographic systems.

PubMed

Samei, Ehsan; Buhr, Egbert; Granfors, Paul; Vandenbroucke, Dirk; Wang, Xiaohui

2005-08-07

The modulation transfer function (MTF) is well established as a metric to characterize the resolution performance of a digital radiographic system. Implemented by various laboratories, the edge technique is currently the most widespread approach to measure the MTF. However, there can be differences in the results attributed to differences in the analysis technique employed. The objective of this study was to determine whether comparable results can be obtained from different algorithms processing identical images representative of those of current digital radiographic systems. Five laboratories participated in a round-robin evaluation of six different algorithms including one prescribed in the International Electrotechnical Commission (IEC) 62220-1 standard. The algorithms were applied to two synthetic and 12 real edge images from different digital radiographic systems including CR, and direct- and indirect-conversion detector systems. The results were analysed in terms of variability as well as accuracy of the resulting presampled MTFs. The results indicated that differences between the individual MTFs and the mean MTF were largely below 0.02. In the case of the two simulated edge images, all algorithms yielded similar results within 0.01 of the expected true MTF. The findings indicated that all algorithms tested in this round-robin evaluation, including the IEC-prescribed algorithm, were suitable for accurate MTF determination from edge images, provided the images are not excessively noisy. The agreement of the MTF results was judged sufficient for the measurement of the MTF necessary for the determination of the DQE.

The Master Transcription Factor mtfA Governs Aflatoxin Production, Morphological Development and Pathogenicity in the Fungus Aspergillus flavus.

PubMed

Zhuang, Zhenhong; Lohmar, Jessica M; Satterlee, Timothy; Cary, Jeffrey W; Calvo, Ana M

2016-01-20

Aspergillus flavus produces a variety of toxic secondary metabolites; among them, the aflatoxins (AFs) are the most well known. These compounds are highly mutagenic and carcinogenic, particularly AFB₁. A. flavus is capable of colonizing a number of economically-important crops, such as corn, cotton, peanut and tree nuts, and contaminating them with AFs. Molecular genetic studies in A. flavus could identify novel gene targets for use in strategies to reduce AF contamination and its adverse impact on food and feed supplies worldwide. In the current study, we investigated the role of the master transcription factor gene mtfA in A. flavus. Our results revealed that forced overexpression of mtfA results in a drastic decrease or elimination of several secondary metabolites, among them AFB₁. The reduction in AFB₁ was accompanied by a decrease in aflR expression. Furthermore, mtfA also regulates development; conidiation was influenced differently by this gene depending on the type of colonized substrate. In addition to its effect on conidiation, mtfA is necessary for the normal maturation of sclerotia. Importantly, mtfA positively affects the pathogenicity of A. flavus when colonizing peanut seeds. AF production in colonized seeds was decreased in the deletion mtfA strain and particularly in the overexpression strain, where only trace amounts were detected. Interestingly, a more rapid colonization of the seed tissue occurred when mtfA was overexpressed, coinciding with an increase in lipase activity and faster maceration of the oily part of the seed.

A Digital Sensor Simulator of the Pushbroom Offner Hyperspectral Imaging Spectrometer

PubMed Central

Tao, Dongxing; Jia, Guorui; Yuan, Yan; Zhao, Huijie

2014-01-01

Sensor simulators can be used in forecasting the imaging quality of a new hyperspectral imaging spectrometer, and generating simulated data for the development and validation of the data processing algorithms. This paper presents a novel digital sensor simulator for the pushbroom Offner hyperspectral imaging spectrometer, which is widely used in the hyperspectral remote sensing. Based on the imaging process, the sensor simulator consists of a spatial response module, a spectral response module, and a radiometric response module. In order to enhance the simulation accuracy, spatial interpolation-resampling, which is implemented before the spatial degradation, is developed to compromise the direction error and the extra aliasing effect. Instead of using the spectral response function (SRF), the dispersive imaging characteristics of the Offner convex grating optical system is accurately modeled by its configuration parameters. The non-uniformity characteristics, such as keystone and smile effects, are simulated in the corresponding modules. In this work, the spatial, spectral and radiometric calibration processes are simulated to provide the parameters of modulation transfer function (MTF), SRF and radiometric calibration parameters of the sensor simulator. Some uncertainty factors (the stability, band width of the monochromator for the spectral calibration, and the integrating sphere uncertainty for the radiometric calibration) are considered in the simulation of the calibration process. With the calibration parameters, several experiments were designed to validate the spatial, spectral and radiometric response of the sensor simulator, respectively. The experiment results indicate that the sensor simulator is valid. PMID:25615727

Assessing the Performance of Military Treatment Facilities

DTIC Science & Technology

2011-01-01

NUMBER OF PAGES 140 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c . THIS PAGE unclassified Standard Form...Benchmark Analysis of MTF Outcomes . . . . . . . . 73 C . Outpatient utilization and MTF Size...and FY 2006, Mean by MTF Size Quintile . . . . . . . . . . . . . . . . . . . . . 99 C .1. Regression of Outpatient Utilization

Differences in personality traits between male-to-female and female-to-male gender identity disorder subjects.

PubMed

Miyajima, Eiichi; Taira, Naoki; Koda, Munenaga; Kondo, Tsuyoshi

2014-12-15

The present study aimed to investigate differences in personality traits among male-to-female (MtF), female-to-male (FtM) gender identity disorder (GID) subjects and non-transsexual male (M) and female (F) controls. Subjects were 72 MtF and 187 FtM GID subjects without psychiatric comorbidities together with 184 male and 159 female non-transsexual controls. Personality traits were assessed using a short version of the Temperament and Character Inventory (TCI-125). Group comparisons were made by two-way ANOVA. Statistical significances were observed as follows: 1) lower novelty seeking in FtM than in M or MtF, 2) higher reward dependence in FtM than in M, 3) higher cooperativeness in FtM than in M or MtF, 4) the highest self-transcendence in MtF among all the groups. The highest self-transcendence in MtF subjects may reflect their vulnerable identity and constrained adaptation to society as the minority. Nevertheless, higher reward dependence and cooperativeness in FtM subjects can be related to more determined motivation for the treatments of GID and might promise better social functioning and adjustment than MtF subjects. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Performance of SEM scintillation detector evaluated by modulation transfer function and detective quantum efficiency function.

PubMed

Bok, Jan; Schauer, Petr

2014-01-01

In the paper, the SEM detector is evaluated by the modulation transfer function (MTF) which expresses the detector's influence on the SEM image contrast. This is a novel approach, since the MTF was used previously to describe only the area imaging detectors, or whole imaging systems. The measurement technique and calculation of the MTF for the SEM detector are presented. In addition, the measurement and calculation of the detective quantum efficiency (DQE) as a function of the spatial frequency for the SEM detector are described. In this technique, the time modulated e-beam is used in order to create well-defined input signal for the detector. The MTF and DQE measurements are demonstrated on the Everhart-Thornley scintillation detector. This detector was alternated using the YAG:Ce, YAP:Ce, and CRY18 single-crystal scintillators. The presented MTF and DQE characteristics show good imaging properties of the detectors with the YAP:Ce or CRY18 scintillator, especially for a specific type of the e-beam scan. The results demonstrate the great benefit of the description of SEM detectors using the MTF and DQE. In addition, point-by-point and continual-sweep e-beam scans in SEM were discussed and their influence on the image quality was revealed using the MTF. © 2013 Wiley Periodicals, Inc.

The parkin Mutant Phenotype in the Fly Is Largely Rescued by Metal-Responsive Transcription Factor (MTF-1) ▿ †

PubMed Central

Saini, Nidhi; Georgiev, Oleg; Schaffner, Walter

2011-01-01

The gene for Parkin, an E3 ubiquitin ligase, is mutated in some familial forms of Parkinson's disease, a severe neurodegenerative disorder. A homozygous mutant of the Drosophila ortholog of human parkin is viable but results in severe motoric impairment including an inability to fly, female and male sterility, and a decreased life span. We show here that a double mutant of the genes for Parkin and the metal-responsive transcription factor 1 (MTF-1) is not viable. MTF-1, which is conserved from insects to mammals, is a key regulator of heavy metal homeostasis and detoxification and plays additional roles in other stress conditions, notably oxidative stress. In contrast to the synthetic lethality of the double mutant, elevated expression of MTF-1 dramatically ameliorates the parkin mutant phenotype, as evidenced by a prolonged life span, motoric improvement including short flight episodes, and female fertility. At the cellular level, muscle and mitochondrial structures are substantially improved. A beneficial effect is also seen with a transgene encoding human MTF-1. We propose that Parkin and MTF-1 provide complementary functions in metal homeostasis, oxidative stress and other cellular stress responses. Our findings also raise the possibility that MTF-1 gene polymorphisms in humans could affect the severity of Parkinson's disease. PMID:21383066

Genetic variation in metallothionein and metal-regulatory transcription factor 1 in relation to urinary cadmium, copper, and zinc

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

Adams, Scott V., E-mail: sadams@fhcrc.org; Barrick, Brian; Christopher, Emily P.

Background: Metallothionein (MT) proteins play critical roles in the physiological handling of both essential (Cu and Zn) and toxic (Cd) metals. MT expression is regulated by metal-regulatory transcription factor 1 (MTF1). Hence, genetic variation in the MT gene family and MTF1 might influence excretion of these metals. Methods: 321 women were recruited in Seattle, WA and Las Cruces, NM and provided demographic information, urine samples for measurement of metal concentrations by mass spectrometry and creatinine, and blood or saliva for extraction of DNA. Forty-one single nucleotide polymorphisms (SNPs) within the MTF1 gene region and the region of chromosome 16 encodingmore » the MT gene family were selected for genotyping in addition to an ancestry informative marker panel. Linear regression was used to estimate the association of SNPs with urinary Cd, Cu, and Zn, adjusted for age, urinary creatinine, smoking history, study site, and ancestry. Results: Minor alleles of rs28366003 and rs10636 near the MT2A gene were associated with lower urinary Cd, Cu, and Zn. Minor alleles of rs8044719 and rs1599823, near MT1A and MT1B, were associated with lower urinary Cd and Zn, respectively. Minor alleles of rs4653329 in MTF1 were associated with lower urinary Cd. Conclusions: These results suggest that genetic variation in the MT gene region and MTF1 influences urinary Cd, Cu, and Zn excretion. - Highlights: • Genetic variation in metallothionein (MT) genes was assessed in two diverse populations. • Single nucleotide polymorphisms (SNPs) in MT genes were associated with mean urinary Cd, Cu and Zn. • Genetic variation may influence biomarkers of exposure, and associations of exposure with health.« less

[Comparison of noise characteristics of direct and indirect conversion flat panel detectors].

PubMed

Murai, Masami; Kishimoto, Kenji; Tanaka, Katsuhisa; Oota, Kenji; Ienaga, Akinori

2010-11-20

Flat-panel detector (FPD) digital radiography systems have direct and indirect conversion systems, and the 2 conversion systems provide different imaging performances. We measured some imaging performances [input-output characteristic, presampled modulation transfer function (presampled MTF), noise power spectrum (NPS)] of direct and indirect FPD systems. Moreover, some image samples of the NPSs were visually evaluated by the pair comparison method. As a result, the presampled MTF of the direct FPD system was substantially higher than that of the indirect FPD system. The NPS of the direct FPD system had a high value for all spatial frequencies. In contrast, the NPS of the indirect FPD system had a lower value as the frequency became higher. The results of visual evaluations showed the same tendency as that found for NPSs. We elucidated the cause of the difference in NPSs in a simulation study, and we determined that the cause of the difference in the noise components of the direct and indirect FPD systems was closely related to the presampled MTF.

MTF Driven by Plasma Liner Dynamically Formed by the Merging of Plasma Jets: An Overview

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Eskridge, Richard; Martin, Adam; Smith, James; Lee, Michael; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

One approach for standoff delivery of the momentum flux for compressing the target in MTF consists of using a spherical array of plasma jets to form a spherical plasma shell imploding towards the center of a magnetized plasma, a compact toroid (Figure 1). A 3-year experiment (PLX-1) to explore the physics of forming a 2-D plasma liner (shell) by merging plasma jets is described. An overview showing how this 3-year project (PLX-1) fits into the program plan at the national and international level for realizing MTF for energy and propulsion is discussed. Assuming that there will be a parallel program in demonstrating and establishing the underlying physics principles of MTF using whatever liner is appropriate (e.g. a solid liner) with a goal of demonstrating breakeven by 2010, the current research effort at NASA MSFC attempts to complement such a program by addressing the issues of practical embodiment of MTF for propulsion. Successful conclusion of PLX-1 will be followed by a Physics Feasibility Experiment (PLX-2) for the Plasma Liner Driven MTF.

Orthopedic surgeons' attitudes to osteoporosis investigation and management after minimal trauma fracture (MTF).

PubMed

Anderson-Wurf, Jane; McGirr, Joe; Seal, Alexa; Harding, Catherine

2017-12-01

A study of orthopedic surgeons in rural and regional Southeast Australia to determine attitudes to investigation and management of osteoporosis found they believe follow-up in regard to osteoporosis after MTF is important; responsibility for follow-up diagnosis and management lies with primary health care and current communication systems are poor. The investigation and treatment of osteoporosis after minimal trauma fracture (MTF) is regarded as sub-optimal. There is strong evidence of the benefit of identifying and treating osteoporosis after MTF, and there has been discussion of the possible role that orthopedic surgeons might play in the management of osteoporosis after MTF. The study surveyed orthopedic surgeons in rural and regional Southeast Australia to determine their attitudes to investigation and management of osteoporosis, the role health professionals should play, and the communication and co-ordination of follow-up care. A survey was developed and piloted prior to being posted to 69 orthopedic surgeons asking for their opinions about the general management of osteoporosis, and the roles and responsibilities of health professionals in dealing with osteoporosis following an MTF. Responses were received from 42 participants (60.8%) with the majority of respondents agreeing that it is important to treat osteoporosis following MTF. Less than 15% of respondents felt that it was their responsibility to initiate discussion or treatment or investigation after MTF. No respondent felt that the coordination of osteoporosis care was good and 45% stated it was poor. Communication after discharge is mostly left to the hospital (30%), while 20% stated they did not follow up at all. This study shows that many rural orthopedic surgeons believe that follow-up in regard to osteoporosis after MTF is important, that responsibility for follow-up diagnosis and management of osteoporosis lies with primary health care and the current communication systems are poor.

Hi-Res scan mode in clinical MDCT systems: Experimental assessment of spatial resolution performance

PubMed Central

Cruz-Bastida, Juan P.; Gomez-Cardona, Daniel; Li, Ke; Sun, Heyi; Hsieh, Jiang; Szczykutowicz, Timothy P.; Chen, Guang-Hong

2016-01-01

Purpose: The introduction of a High-Resolution (Hi-Res) scan mode and another associated option that combines Hi-Res mode with the so-called High Definition (HD) reconstruction kernels (referred to as a Hi-Res/HD mode in this paper) in some multi-detector CT (MDCT) systems offers new opportunities to increase spatial resolution for some clinical applications that demand high spatial resolution. The purpose of this work was to quantify the in-plane spatial resolution along both the radial direction and tangential direction for the Hi-Res and Hi-Res/HD scan modes at different off-center positions. Methods: A technique was introduced and validated to address the signal saturation problem encountered in the attempt to quantify spatial resolution for the Hi-Res and Hi-Res/HD scan modes. Using the proposed method, the modulation transfer functions (MTFs) of a 64-slice MDCT system (Discovery CT750 HD, GE Healthcare) equipped with both Hi-Res and Hi-Res/HD modes were measured using a metal bead at nine different off-centered positions (0–16 cm with a step size of 2 cm); at each position, both conventional scans and Hi-Res scans were performed. For each type of scan and position, 80 repeated acquisitions were performed to reduce noise induced uncertainties in the MTF measurements. A total of 15 reconstruction kernels, including eight conventional kernels and seven HD kernels, were used to reconstruct CT images of the bead. An ex vivo animal study consisting of a bone fracture model was performed to corroborate the MTF results, as the detection of this high-contrast and high frequency task is predominantly determined by spatial resolution. Images of this animal model generated by different scan modes and reconstruction kernels were qualitatively compared with the MTF results. Results: At the centered position, the use of Hi-Res mode resulted in a slight improvement in the MTF; each HD kernel generated higher spatial resolution than its counterpart conventional kernel. However, the MTF along the tangential direction of the scan field of view (SFOV) was significantly degraded at off-centered positions, yet the combined Hi-Res/HD mode reduced this azimuthal MTF degradation. Images of the animal bone fracture model confirmed the improved spatial resolution at the off-centered positions through the use of the Hi-Res mode and HD kernels. Conclusions: The Hi-Res/HD scan improve spatial resolution of MDCT systems at both centered and off-centered positions. PMID:27147351

The Choice of Enzyme for Human Pancreas Digestion is a Critical Factor for Increasing the Success of Islet Isolation.

PubMed

Qi, Meirigeng; Valiente, Luis; McFadden, Brian; Omori, Keiko; Bilbao, Shiela; Juan, Jemily; Rawson, Jeffrey; Scott, Stephen; Ferreri, Kevin; Mullen, Yoko; El-Shahawy, Mohamed; Dafoe, Donald; Kandeel, Fouad; Al-Abdullah, Ismail H

2015-05-01

We evaluated three commercially available enzymes for pancreatic digestion by comparing key parameters during the islet isolation process, as well as islet quality post-isolation. Retrospectively compared and analyzed islet isolations from pancreata using three different enzyme groups: Liberase HI (n=63), Collagenase NB1/Neutral Protease (NP) (n=43), and Liberase Mammalian Tissue Free Collagenase/Thermolysin (MTF C/T) (n=115). A standardized islet isolation and purification method was used. Islet quality assessment was carried out using islet count, viability, in vitro glucose-stimulated insulin secretion (GSIS), glucose-stimulated oxygen consumption rate (ΔOCR), and in vivo transplantation model in mice. Donor characteristics were not significantly different among the three enzyme groups used in terms of age, sex, hospital stay duration, cause of death, body mass index (BMI), hemoglobin A1c (HbA1c), cold ischemia time (CIT), and pancreas weight. Digestion efficacy (percentage of digested tissue by weight) was significantly higher in the Liberase MTF C/T group (73.5 ± 1.5 %) when compared to the Liberase HI group (63.6 ± 2.3 %) (p<0.001) and the Collagenase NB1/NP group (61.7 ± 2.9%) (p<0.001). The stimulation index for GSIS was significantly higher in the Liberase MTF C/T group (5.3 ± 0.5) as compared to the Liberase HI (2.9 ± 0.2) (p<0.0001) and the Collagenase NB1/NP (3.6 ± 2.9) (p=0.012) groups. Furthermore, the Liberase MTF C/T enzymes showed the highest success rate of transplantation in diabetic NOD Scid mice (65%), which was significantly higher than the Liberase HI (42%, p=0.001) and the Collagenase NB1/NP enzymes (41%, p<0.001). Liberase MTF C/T is superior to Liberase HI and Collagenase NB1/NP in terms of digestion efficacy and glucose-stimulated insulin secretion in vitro . Moreover, Liberase MTF C/T had a significantly higher success rate of transplantation in diabetic NOD Scid mice compared to Liberase HI and Collagenase NB1/NP enzymes.

76 FR 39043 - TRICARE; Reimbursement of Sole Community Hospitals and Adjustment to Reimbursement of Critical...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-05

... hospitals located within Military Treatment Facility (MTF) Prime Service Areas (PSAs) and deemed essential... costs. It has come to our attention that there may be some CAHs located in MTF PSAs that are deemed... proposing a CAH TMCPA for TRICARE network hospitals located within MTF PSAs and deemed essential for...

Improvement of spatial resolution in a Timepix based CdTe photon counting detector using ToT method

NASA Astrophysics Data System (ADS)

Park, Kyeongjin; Lee, Daehee; Lim, Kyung Taek; Kim, Giyoon; Chang, Hojong; Yi, Yun; Cho, Gyuseong

2018-05-01

Photon counting detectors (PCDs) have been recognized as potential candidates in X-ray radiography and computed tomography due to their many advantages over conventional energy-integrating detectors. In particular, a PCD-based X-ray system shows an improved contrast-to-noise ratio, reduced radiation exposure dose, and more importantly, exhibits a capability for material decomposition with energy binning. For some applications, a very high resolution is required, which translates into smaller pixel size. Unfortunately, small pixels may suffer from energy spectral distortions (distortion in energy resolution) due to charge sharing effects (CSEs). In this work, we propose a method for correcting CSEs by measuring the point of interaction of an incident X-ray photon by the time-of-threshold (ToT) method. Moreover, we also show that it is possible to obtain an X-ray image with a reduced pixel size by using the concept of virtual pixels at a given pixel size. To verify the proposed method, modulation transfer function (MTF) and signal-to-noise ratio (SNR) measurements were carried out with the Timepix chip combined with the CdTe pixel sensor. The X-ray test condition was set at 80 kVp with 5 μA, and a tungsten edge phantom and a lead line phantom were used for the measurements. Enhanced spatial resolution was achieved by applying the proposed method when compared to that of the conventional photon counting method. From experiment results, MTF increased from 6.3 (conventional counting method) to 8.3 lp/mm (proposed method) at 0.3 MTF. On the other hand, the SNR decreased from 33.08 to 26.85 dB due to four virtual pixels.

A comprehensive model for x-ray projection imaging system efficiency and image quality characterization in the presence of scattered radiation

NASA Astrophysics Data System (ADS)

Monnin, P.; Verdun, F. R.; Bosmans, H.; Rodríguez Pérez, S.; Marshall, N. W.

2017-07-01

This work proposes a method for assessing the detective quantum efficiency (DQE) of radiographic imaging systems that include both the x-ray detector and the antiscatter device. Cascaded linear analysis of the antiscatter device efficiency (DQEASD) with the x-ray detector DQE is used to develop a metric of system efficiency (DQEsys); the new metric is then related to the existing system efficiency parameters of effective DQE (eDQE) and generalized DQE (gDQE). The effect of scatter on signal transfer was modelled through its point spread function (PSF), leading to an x-ray beam transfer function (BTF) that multiplies with the classical presampling modulation transfer function (MTF) to give the system MTF. Expressions are then derived for the influence of scattered radiation on signal-difference to noise ratio (SDNR) and contrast-detail (c-d) detectability. The DQEsys metric was tested using two digital mammography systems, for eight x-ray beams (four with and four without scatter), matched in terms of effective energy. The model was validated through measurements of contrast, SDNR and MTF for poly(methyl)methacrylate thicknesses covering the range of scatter fractions expected in mammography. The metric also successfully predicted changes in c-d detectability for different scatter conditions. Scatter fractions for the four beams with scatter were established with the beam stop method using an extrapolation function derived from the scatter PSF, and validated through Monte Carlo (MC) simulations. Low-frequency drop of the MTF from scatter was compared to both theory and MC calculations. DQEsys successfully quantified the influence of the grid on SDNR and accurately gave the break-even object thickness at which system efficiency was improved by the grid. The DQEsys metric is proposed as an extension of current detector characterization methods to include a performance evaluation in the presence of scattered radiation, with an antiscatter device in place.

Validation of a Custom-made Software for DQE Assessment in Mammography Digital Detectors

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

Ayala-Dominguez, L.; Perez-Ponce, H.; Brandan, M. E.

2010-12-07

This works presents the validation of a custom-made software, designed and developed in Matlab, intended for routine evaluation of detective quantum efficiency DQE, according to algorithms described in the IEC 62220-1-2 standard. DQE, normalized noise power spectrum NNPS and pre-sampling modulation transfer function MTF were calculated from RAW images from a GE Senographe DS (FineView disabled) and a Siemens Novation system. Calculated MTF is in close agreement with results obtained with alternative codes: MTF lowbar tool (Maidment), ImageJ plug-in (Perez-Ponce) and MIQuaELa (Ayala). Overall agreement better than {approx_equal}90% was found in MTF; the largest differences were observed at frequencies closemore » to the Nyquist limit. For the measurement of NNPS and DQE, agreement is similar to that obtained in the MTF. These results suggest that the developed software can be used with confidence for image quality assessment.« less

Modulation transfer function measurement of microbolometer focal plane array by Lloyd's mirror method

NASA Astrophysics Data System (ADS)

Druart, Guillaume; Rommeluere, Sylvain; Viale, Thibault; Guerineau, Nicolas; Ribet-Mohamed, Isabelle; Crastes, Arnaud; Durand, Alain; Taboury, Jean

2014-05-01

Today, both military and civilian applications require miniaturized and cheap optical systems. One way to achieve this trend consists in decreasing the pixel pitch of focal plane arrays (FPA). In order to evaluate the performance of the overall optical systems, it is necessary to measure the modulation transfer function (MTF) of these pixels. However, small pixels lead to higher cut-off frequencies and therefore, original MTF measurements that are able to extract frequencies up to these high cut-off frequencies, are needed. In this paper, we will present a way to extract 1D MTF at high frequencies by projecting fringes on the FPA. The device uses a Lloyd mirror placed near and perpendicular to the focal plane array. Consequently, an interference pattern of fringes can be projected on the detector. By varying the angle of incidence of the light beam, we can tune the period of the interference fringes and, thus, explore a wide range of spatial frequencies, and mainly around the cut-off frequency of the pixel which is one of the most interesting area. Illustration of this method will be applied to a 640×480 microbolometer focal plane array with a pixel pitch of 17µm in the LWIR spectral region.

Remote Sensing Image Quality Assessment Experiment with Post-Processing

NASA Astrophysics Data System (ADS)

Jiang, W.; Chen, S.; Wang, X.; Huang, Q.; Shi, H.; Man, Y.

2018-04-01

This paper briefly describes the post-processing influence assessment experiment, the experiment includes three steps: the physical simulation, image processing, and image quality assessment. The physical simulation models sampled imaging system in laboratory, the imaging system parameters are tested, the digital image serving as image processing input are produced by this imaging system with the same imaging system parameters. The gathered optical sampled images with the tested imaging parameters are processed by 3 digital image processes, including calibration pre-processing, lossy compression with different compression ratio and image post-processing with different core. Image quality assessment method used is just noticeable difference (JND) subject assessment based on ISO20462, through subject assessment of the gathered and processing images, the influence of different imaging parameters and post-processing to image quality can be found. The six JND subject assessment experimental data can be validated each other. Main conclusions include: image post-processing can improve image quality; image post-processing can improve image quality even with lossy compression, image quality with higher compression ratio improves less than lower ratio; with our image post-processing method, image quality is better, when camera MTF being within a small range.

Associations between the Transsexual Voice Questionnaire (TVQ[superscript MtF) and Self-Report of Voice Femininity and Acoustic Voice Measures

ERIC Educational Resources Information Center

Dacakis, Georgia; Oates, Jennifer; Douglas, Jacinta

2017-01-01

Background: The Transsexual Voice Questionnaire (TVQ[Superscript MtF]) was designed to capture the voice-related perceptions of individuals whose gender identity as female is the opposite of their birth-assigned gender (MtF women). Evaluation of the psychometric properties of the TVQ[Superscript MtF]is ongoing. Aims: To investigate associations…

Simulating muscular thin films using thermal contraction capabilities in finite element analysis tools.

PubMed

Webster, Victoria A; Nieto, Santiago G; Grosberg, Anna; Akkus, Ozan; Chiel, Hillel J; Quinn, Roger D

2016-10-01

In this study, new techniques for approximating the contractile properties of cells in biohybrid devices using Finite Element Analysis (FEA) have been investigated. Many current techniques for modeling biohybrid devices use individual cell forces to simulate the cellular contraction. However, such techniques result in long simulation runtimes. In this study we investigated the effect of the use of thermal contraction on simulation runtime. The thermal contraction model was significantly faster than models using individual cell forces, making it beneficial for rapidly designing or optimizing devices. Three techniques, Stoney׳s Approximation, a Modified Stoney׳s Approximation, and a Thermostat Model, were explored for calibrating thermal expansion/contraction parameters (TECPs) needed to simulate cellular contraction using thermal contraction. The TECP values were calibrated by using published data on the deflections of muscular thin films (MTFs). Using these techniques, TECP values that suitably approximate experimental deflections can be determined by using experimental data obtained from cardiomyocyte MTFs. Furthermore, a sensitivity analysis was performed in order to investigate the contribution of individual variables, such as elastic modulus and layer thickness, to the final calibrated TECP for each calibration technique. Additionally, the TECP values are applicable to other types of biohybrid devices. Two non-MTF models were simulated based on devices reported in the existing literature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Space station interior noise analysis program

NASA Technical Reports Server (NTRS)

Stusnick, E.; Burn, M.

1987-01-01

Documentation is provided for a microcomputer program which was developed to evaluate the effect of the vibroacoustic environment on speech communication inside a space station. The program, entitled Space Station Interior Noise Analysis Program (SSINAP), combines a Statistical Energy Analysis (SEA) prediction of sound and vibration levels within the space station with a speech intelligibility model based on the Modulation Transfer Function and the Speech Transmission Index (MTF/STI). The SEA model provides an effective analysis tool for predicting the acoustic environment based on proposed space station design. The MTF/STI model provides a method for evaluating speech communication in the relatively reverberant and potentially noisy environments that are likely to occur in space stations. The combinations of these two models provides a powerful analysis tool for optimizing the acoustic design of space stations from the point of view of speech communications. The mathematical algorithms used in SSINAP are presented to implement the SEA and MTF/STI models. An appendix provides an explanation of the operation of the program along with details of the program structure and code.

Sentinel-2 radiometric image quality commissioning: first results

NASA Astrophysics Data System (ADS)

Lachérade, S.; Lonjou, V.; Farges, M.; Gamet, P.; Marcq, S.; Raynaud, J.-L.; Trémas, T.

2015-10-01

In partnership with the European Commission and in the frame of the Copernicus program, the European Space Agency (ESA) is developing the Sentinel-2 optical imaging mission devoted to the operational monitoring of land and coastal areas. The Sentinel-2 mission is based on a satellites constellation deployed in polar sun-synchronous orbit. Sentinel-2 offers a unique combination of global coverage with a wide field of view (290km), a high revisit (5 days with two satellites), a high spatial resolution (10m, 20m and 60m) and multi-spectral imagery (13 spectral bands in visible and shortwave infrared domains). The first satellite, Sentinel-2A, has been launched in June 2015. The Sentinel-2A Commissioning Phase starts immediately after the Launch and Early Orbit Phase and continues until the In-Orbit Commissioning Review which is planned three months after the launch. The Centre National d'Etudes Spatiales (CNES) supports ESA/ESTEC to insure the Calibration/Validation commissioning phase during the first three months in flight. This paper provides first an overview of the Sentinel-2 system and a description of the products delivered by the ground segment associated to the main radiometric specifications to achieve. Then the paper focuses on the preliminary radiometric results obtained during the in-flight commissioning phase. The radiometric methods and calibration sites used in the CNES image quality center to reach the specifications of the sensor are described. A status of the Sentinel-2A radiometric performances at the end of the first three months after the launch is presented. We will particularly address in this paper the results in term of absolute calibration, pixel to pixel relative sensitivity and MTF estimation.

Simulation of the modulation transfer function dependent on the partial Fourier fraction in dynamic contrast enhancement magnetic resonance imaging.

PubMed

Takatsu, Yasuo; Ueyama, Tsuyoshi; Miyati, Tosiaki; Yamamura, Kenichirou

2016-12-01

The image characteristics in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) depend on the partial Fourier fraction and contrast medium concentration. These characteristics were assessed and the modulation transfer function (MTF) was calculated by computer simulation. A digital phantom was created from signal intensity data acquired at different contrast medium concentrations on a breast model. The frequency images [created by fast Fourier transform (FFT)] were divided into 512 parts and rearranged to form a new image. The inverse FFT of this image yielded the MTF. From the reference data, three linear models (low, medium, and high) and three exponential models (slow, medium, and rapid) of the signal intensity were created. Smaller partial Fourier fractions, and higher gradients in the linear models, corresponded to faster MTF decline. The MTF more gradually decreased in the exponential models than in the linear models. The MTF, which reflects the image characteristics in DCE-MRI, was more degraded as the partial Fourier fraction decreased.

The effect of split pixel HDR image sensor technology on MTF measurements

NASA Astrophysics Data System (ADS)

Deegan, Brian M.

2014-03-01

Split-pixel HDR sensor technology is particularly advantageous in automotive applications, because the images are captured simultaneously rather than sequentially, thereby reducing motion blur. However, split pixel technology introduces artifacts in MTF measurement. To achieve a HDR image, raw images are captured from both large and small sub-pixels, and combined to make the HDR output. In some cases, a large sub-pixel is used for long exposure captures, and a small sub-pixel for short exposures, to extend the dynamic range. The relative size of the photosensitive area of the pixel (fill factor) plays a very significant role in the output MTF measurement. Given an identical scene, the MTF will be significantly different, depending on whether you use the large or small sub-pixels i.e. a smaller fill factor (e.g. in the short exposure sub-pixel) will result in higher MTF scores, but significantly greater aliasing. Simulations of split-pixel sensors revealed that, when raw images from both sub-pixels are combined, there is a significant difference in rising edge (i.e. black-to-white transition) and falling edge (white-to-black) reproduction. Experimental results showed a difference of ~50% in measured MTF50 between the falling and rising edges of a slanted edge test chart.

Assessment of motivation to control alcohol use: The motivational thought frequency and state motivation scales for alcohol control.

PubMed

Robinson, Nicole; Kavanagh, David; Connor, Jason; May, Jon; Andrade, Jackie

2016-08-01

The Elaborated Intrusion Theory of Desire holds that desires for functional and dysfunctional goals share a common form. Both are embodied cognitive events, characterised by affective intensity and frequency. Accordingly, we developed scales to measure motivational cognitions for functional goals (Motivational Thought Frequency, MTF; State Motivation, SM), based on the existing Craving Experience Questionnaire (CEQ). When applied to increasing exercise, MTF and SM showed the same three-factor structure as the CEQ (Intensity, Imagery, Availability). The current study tested the internal structure and concurrent validity of the MTF and SM Scales when applied to control of alcohol consumption (MTF-A; SM-A). Participants (N=417) were adult tertiary students, staff or community members who had recently engaged in high-risk drinking or were currently trying to control alcohol consumption. They completed an online survey comprising the MTF-A, SM-A, Alcohol Use Disorders Identification Test (AUDIT), Readiness to Change Questionnaire (RCQ) and demographics. Confirmatory Factor Analysis gave acceptable fit for the MTF-A, but required the loss of one SM-A item, and was improved by intercorrelations of error terms. Higher scores were associated with more severe problems on the AUDIT and with higher Contemplation and Action scores on the RCQ. The MTF-A and SM-A show potential as measures of motivation to control drinking. Future research will examine their predictive validity and sensitivity to change. The scales' application to both increasing functional and decreasing dysfunctional behaviours is consistent with EI Theory's contention that both goal types operate in similar ways. Copyright © 2016 Elsevier Ltd. All rights reserved.

The significance of measuring monocyte tissue factor activity in patients with breast and colorectal cancer

PubMed Central

Lwaleed, B A; Chisholm, M; Francis, J L

1999-01-01

Monocytes express tissue factor (mTF) in several conditions including cancer where levels may be valuable in assessing tumour presence and progression. Using a two-stage kinetic chromogenic assay (KCA), mTF levels were measured in controls [normal subjects (n = 60) and patients undergoing hernia repair or cholecystectomy (n = 60)], in patients with benign and malignant disease of the breast (n = 83) and of the large bowel (n = 62). This was performed under fresh (resting) conditions and after incubation for 6 h without (unstimulated) and with (stimulated) Escherichia coli endotoxin. The malignant groups showed higher mTF levels than each of the three controls for resting (P < 0.05 breast, P < 0.05 colorectal) unstimulated (P < 0.05 breast, P < 0.05 colorectal) and stimulated cells (P < 0.001 breast, P < 0.01 colorectal). Similarly, the benign inflammatory groups had higher mTF levels than controls for resting (P < 0.05 colorectal), unstimulated (P < 0.05 colorectal) and stimulated cells (P < 0.01 breast, P < 0.01 colorectal). There was no significant difference between malignant and benign inflammatory groups in each organ. mTF levels showed an increase corresponding to that of histological tumour progression and were higher in non-surviving patients. In conclusion, mTF levels are raised in malignant and inflammatory disease compared to controls and patients with non-inflammatory conditions. Stimulated cells give better discrimination between the groups and may be of value in identifying high risk individuals. mTF levels showed an association with tumour grade or stage and the patients' survival time. © 1999 Cancer Research Campaign PMID:10390009

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

Bache, S; Rong, J

Purpose: To quantify a radiology team’s assessment of image quality differences between two CT scanner models currently in clinical use, with emphasis on spatial resolution that could be impacted by focal spot size. Methods: Modulation Transfer Functions (MTF) measurements were performed by scanning the impulse source insert module of the Catphan 600 at 120/140 kVp with both large (LFS) and small (SFS) focal spots and reconstructed to 2.5mm and 5.0mm thicknesses on a GE Discovery CT750 HD and a LightSpeed VCT CT scanner. MTFs were calculated by summing the 2D PSF along one-dimension to obtain line-spread-function (LSF), and calculating themore » Fourier Transform of the zero-padded and background corrected LSF. Spatial resolution performance was evaluated by comparing MTF curves, 50% and 10% MTF cutoff, and total area under the MTF curve (AUC). In addition, images of the Catphan high-contrast module and a Kagaku anthropomorphic body phantom were acquired from the HD scanner for visual comparisons. Results: For each scanner model, SFS was superior to LFS spatial resolution with respect to 50%/10% MTF cutoff and AUC. For the HD, 50%/10% cutoff was 4.29/7.22cm-1 for the LFS and 4.43/7.45cm-1 for the SFS. VCT outperformed HD, with 50%/10% cutoff of 4.40/7.29 cm-1 for LFS and 4.62/7.47cm-1 for SFS. Scanner model performance in order of decreasing AUC performance was VCT SFS (7.43), HD SFS (7.20), VCT LFS (7.09) and HD LFS (6.93). Visual evaluations of Kagaku phantom images confirmed that VCT outperformed HD. Conclusion: VCT outperformed HD and small focal spot is desired for either model over large focal spot in term of spatial resolution – in agreement with radiologist feedback of overall image quality. In-depth evaluations of clinical impact and focal spot selection mechanisms is currently being assessed.« less

Interface healing and its correlation with visual recovery and quality of vision following small incision lenticule extraction

PubMed Central

Ganesh, Sri; Brar, Sheetal; Pandey, Rahul; Pawar, Archana

2018-01-01

Purpose: To study the time course of interface healing and its correlation with visual acuity, modulation transfer function (MTF), and aberrations after myopic small-incision lenticule extraction (SMILE) correction. Methods: Seventy-eight eyes of 78 patients (1 eye per patient) with a mean age of 25.7 years and mean spherical equivalent (SE) of −3.74D, undergoing bilateral SMILE procedure, were included in this study. On postoperative day 1, 2 weeks, and 3 months, dilated retroillumination photographs were taken and morphology of corneal interface was graded by comparing them with 5 standard templates representing 5 grades of interface roughness (IRG): IRG – 0 (clear), IRG – 1 (mild), IRG – 2 (moderate), IRG – 3 (severe), and IRG – 4 (severe IRG with Bowman's folds in visual axis). Pearson's correlations were computed to study correlation associations, and Wilcoxon signed-rank test was used for intragroup comparison of means. P ≤ 0.05 was considered statistically significant. Results: At 3 months, 90.70% eyes were Grade 0 while 9.30% eyes still had Grade 2 interface granularity. Mean IRG significantly improved from 2.47 ± 0.57 at day 1 to 0.62 ± 0.53 at 3 months (P = 0.00). At day 1, pre-SE showed a significant positive correlation with IRG; however, mean postoperative corrected distant visual acuity (CDVA, in decimal), corneal Strehl ratio (SR), and MTF showed weak but significant negative correlation with IRG (r2 = 0.28 for SE, −0.052 for CDVA, −0.017 for SR, and −0.39 for MTF, respectively, P < 0.05 for all correlations). At 2 weeks and 3 months, corneal MTF continued to show a significant negative correlation, whereas other parameters did not show any correlation with IRG. Conclusion: Visual quality and corneal MTF may be significantly affected by the IRG in the immediate postoperative period after SMILE and may take 3 months or more for complete recovery. PMID:29380760

The influence of focal spot blooming on high-contrast spatial resolution in CT imaging.

PubMed

Grimes, Joshua; Duan, Xinhui; Yu, Lifeng; Halaweish, Ahmed F; Haag, Nicole; Leng, Shuai; McCollough, Cynthia

2015-10-01

The objective of this work was to investigate focal spot blooming effects on the spatial resolution of CT images and to evaluate an x-ray tube that uses dynamic focal spot control for minimizing focal spot blooming. The influence of increasing tube current at a fixed tube potential of 80 kV on high-contrast spatial resolution of seven different CT scanner models (scanners A-G), including one scanner that uses dynamic focal spot control to reduce focal spot blooming (scanner A), was evaluated. Spatial resolution was assessed using a wire phantom for the modulation transfer function (MTF) calculation and a copper disc phantom for measuring the slice sensitivity profile (SSP). The impact of varying the tube potential was investigated on two scanner models (scanners A and B) by measuring the MTF and SSP and also by using the resolution bar pattern module of the ACR CT phantom. The phantoms were scanned at 70-150 kV on scanner A and 80-140 kV on scanner B, with tube currents from 100 mA up to the maximum tube current available on each scanner. The images were reconstructed using a slice thickness of 0.6 mm with both smooth and sharp kernels. Additionally, focal spot size at varying tube potentials and currents was directly measured using pinhole and slit camera techniques. Evaluation of the MTF and SSP data from the 7 CT scanner models evaluated demonstrated decreased focal spot blooming for newer scanners, as evidenced by decreasing deviations in MTF and SSP as tube current varied. For scanners A and B, where focal spot blooming effects as a function of tube potential were assessed, the spatial resolution variation in the axial plane was much smaller on scanner A compared to scanner B as tube potential and current changed. On scanner A, the 50% MTF never decreased by more than 2% from the 50% MTF measured at 100 mA. On scanner B, the 50% MTF decreased by as much as 19% from the 50% MTF measured at 100 mA. Assessments of the SSP, the bar patterns in the ACR phantom and the pinhole and slit camera measurements were consistent with the MTF calculations. Focal spot blooming has a noticeable effect on spatial resolution in CT imaging. The focal spot shaping technology of scanner A greatly reduced blooming effects.

Conformational heterogeneity in the C-terminal zinc fingers of human MTF-1: an NMR and zinc-binding study.

PubMed

Giedroc, D P; Chen, X; Pennella, M A; LiWang, A C

2001-11-09

The human metalloregulatory transcription factor, metal-response element (MRE)-binding transcription factor-1 (MTF-1), contains six TFIIIA-type Cys(2)-His(2) motifs, each of which was projected to form well-structured betabetaalpha domains upon Zn(II) binding. In this report, the structure and backbone dynamics of a fragment containing the unusual C-terminal fingers F4-F6 has been investigated. (15)N heteronuclear single quantum coherence (HSQC) spectra of uniformly (15)N-labeled hMTF-zf46 show that Zn(II) induces the folding of hMTF-zf46. Analysis of the secondary structure of Zn(3) hMTF-zf46 determined by (13)Calpha chemical shift indexing and the magnitude of (3)J(Halpha-HN) clearly reveal that zinc fingers F4 and F6 adopt typical betabetaalpha structures. An analysis of the heteronuclear backbone (15)N relaxation dynamics behavior is consistent with this picture and further reveals independent tumbling of the finger domains in solution. Titration of apo-MTF-zf46 with Zn(II) reveals that the F4 domain binds Zn(II) significantly more tightly than do the other two finger domains. In contrast to fingers F4 and F6, the betabetaalpha fold of finger F5 is unstable and only partially populated at substoichiometric Zn(II); a slight molar excess of zinc results in severe conformational exchange broadening of all F5 NH cross-peaks. Finally, although Cd(II) binds to apo-hMTF-zf46 as revealed by intense S(-)-->Cd(II) absorption, a non-native structure results; addition of stoichiometric Zn(II) to the Cd(II) complex results in quantitative refolding of the betabetaalpha structure in F4 and F6. The functional implications of these results are discussed.

Bean Metal-Responsive Element-Binding Transcription Factor Confers Cadmium Resistance in Tobacco1

PubMed Central

Sun, Na; Liu, Meng; Zhang, Wentao; Yang, Wanning; Bei, Xiujuan; Ma, Hui; Qiao, Fan; Qi, Xiaoting

2015-01-01

Cadmium (Cd) is highly toxic to plants. Modulation of Cd-responsive transcription is an important way for Cd detoxification in plants. Metal-responsive element (MRE) is originally described in animal metallothionein genes. Although functional MREs also exist in Cd-regulated plant genes, specific transcription factors that bind MRE to regulate Cd tolerance have not been identified. Previously, we showed that Cd-inducible bean (Phaseolus vulgaris) stress-related gene2 (PvSR2) produces a short (S) PvSR2 transcript (S-PvSR2) driven by an intronic promoter. Here, we demonstrate that S-PvSR2 encodes a bean MRE-binding transcription factor1 (PvMTF-1) that confers Cd tolerance in tobacco (Nicotiana tabacum). PvMTF-1 expression was up-regulated by Cd at the levels of RNA and protein. Importantly, expression of PvMTF-1 in tobacco enhanced Cd tolerance, indicating its role in regulating Cd resistance in planta. This was achieved through direct regulation of a feedback-insensitive Anthranilate Synthase α-2 chain gene (ASA2), which catalyzes the first step for tryptophan biosynthesis. In vitro and in vivo DNA-protein interaction studies further revealed that PvMTF-1 directly binds to the MRE in the ASA2 promoter, and this binding depends on the zinc finger-like motif of PvMTF-1. Through modulating ASA2 up-regulation by Cd, PvMTF-1 increased free tryptophan level and subsequently reduced Cd accumulation, thereby enhancing Cd tolerance of transgenic tobacco plants. Consistent with this observation, tobacco transiently overexpressing ASA2 also exhibited increased tolerance to Cd. We conclude that PvMTF-1 is a zinc finger-like transcription factor that links MRE to Cd resistance in transgenic tobacco through activation of tryptophan biosynthesis. PMID:25624396

Engineering of the Magnetized Target Fusion Propulsion System

NASA Technical Reports Server (NTRS)

Statham, G.; White, S.; Adams, R. B.; Thio, Y. C. F.; Santarius, J.; Alexander, R.; Chapman, J.; Fincher, S.; Philips, A.; Polsgrove, T.

2003-01-01

Engineering details are presented for a magnetized target fusion (MTF) propulsion system designed to support crewed missions to the outer solar system. Basic operation of an MTF propulsion system is introduced. Structural, thermal, radiation-management and electrical design details are presented. The propellant storage and supply system design is also presented. A propulsion system mass estimate and associated performance figures are given. The advantages of helium-3 as a fusion fuel for an advanced MTF system are discussed.

A Single-Centre, Randomized, Double-Blind, Placebo-Controlled Clinical Trial to Investigate the Efficacy and Safety of Minoxidil Topical Foam in Frontotemporal and Vertex Androgenetic Alopecia in Men.

PubMed

Hillmann, Kathrin; Garcia Bartels, Natalie; Kottner, Jan; Stroux, Andrea; Canfield, Douglas; Blume-Peytavi, Ulrike

2015-01-01

5% minoxidil formulations twice daily are effective in treating vertex male androgenetic alopecia (AGA); however, efficacy and safety data in frontotemporal regions are lacking. To assess the efficacy of 5% minoxidil topical foam (5% MTF) in the frontotemporal region of male AGA patients after 24 weeks of treatment compared to placebo treatment and to the vertex region. Seventy males with moderate AGA applied 5% MTF or placebo foam (plaTF) twice daily for 24 weeks in frontotemporal and vertex regions. Target area non-vellus hair count (TAHC) was the primary end point. Frontotemporal and vertex TAHC and target area cumulative non-vellus hair width (TAHW) showed similar responses to 5% MTF with significant increases up to week 16 compared to baseline (p < 0.001). After 24 weeks of treatment, frontotemporal TAHW increased significantly in the 5% MTF group compared to the plaTF group (p = 0.017), while TAHC showed a similar non-significant increase from baseline in both regions. At 24 weeks, 5% MTF users rated a significant improvement in scalp coverage for the frontotemporal (p = 0.016) and vertex areas (p = 0.027). 5% MTF twice a day promotes hair density and width in both frontotemporal and vertex regions in men with moderate stages of AGA. © 2015 S. Karger AG, Basel.

The effect of serum on monocyte tissue factor generation.

PubMed

Edwards, R L; Perla, D

1984-09-01

Human monocytes generate the procoagulant tissue factor (MTF) following exposure to a variety of immune stimuli in vitro. The generation of MTF is modified by T cells, lymphokines, and immunoregulatory lipoproteins, and recent studies have shown that MTF can be activated in an immune-specific manner following exposure to antigen. We have examined the role of serum factors in the regulation of MTF generation. Low concentrations (less than 1%) of heat-inactivated normal human serum greatly enhanced MTF generation in cultures of normal peripheral blood mononuclear cells. The stimulatory effect was observed in cultures of both unstimulated cells and cells exposed to bacterial lipopolysaccharide. Stimulation was not observed at high serum concentrations (greater than 10%) and could not be explained by endotoxin contamination or activation of the assay system. Stimulatory activity was present in plasma and BaSO4-adsorbed plasma as well as autologous and allogeneic serum, was not abolished by removal of serum lipoproteins, and did not require the presence of T cells for its expression. Sera from 28 different normal volunteers were screened for stimulatory activity and demonstrated a wide variation in potency. These results suggest that a potent factor is present in sera that enhances the expression of MTF activity in vitro. This factor is distinct from previously described lipoprotein regulators and may play a role in the initiation of coagulation in both normal hemostasis and pathologic states.

Societal individualism predicts prevalence of nonhomosexual orientation in male-to-female transsexualism.

PubMed

Lawrence, Anne A

2010-04-01

There are two distinct subtypes of male-to-female (MtF) transsexuals: homosexual and nonhomosexual. The relative prevalence of these two subtypes varies dramatically between countries, but no explanation of this variability has yet been proposed. This study examined the hypothesis that the prevalence of nonhomosexual MtF transsexualism, relative to homosexual MtF transsexualism, would be higher in individualistic countries than in collectivistic countries. I analyzed data from 22 studies of MtF transsexualism, conducted in 16 countries, examining the association between percentage of nonhomosexual participants and Hofstede's (Culture's consequences: Comparing values, behaviors, institutions, and organizations across nations, 2001) Individualism Index (IDV). IDV accounted for 77% of observed variance in the percentage of nonhomosexual MtF participants (r = 0.88, p < .0001). Controlling for differences in national wealth and in Hofstede's other indices of societal values (Power Distance, Uncertainty Avoidance, and Masculinity) did not significantly change the ability of IDV to account for variance in the percentage of nonhomosexual participants. The factors that contribute to the observed association between societal individualism and the relative prevalence of nonhomosexual MtF transsexualism remain to be determined, but a greater tolerance within individualistic countries for socially disruptive gender transitions by nonhomosexual gender dysphoric men, and the availability within many collectivistic countries of socially approved transgender roles for pervasively feminine homosexual gender dysphoric men, are plausible contributors.

Evaluation of modulation transfer function of optical lens system by support vector regression methodologies - A comparative study

NASA Astrophysics Data System (ADS)

Petković, Dalibor; Shamshirband, Shahaboddin; Saboohi, Hadi; Ang, Tan Fong; Anuar, Nor Badrul; Rahman, Zulkanain Abdul; Pavlović, Nenad T.

2014-07-01

The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the polynomial and radial basis function (RBF) are applied as the kernel function of Support Vector Regression (SVR) to estimate and predict estimate MTF value of the actual optical system according to experimental tests. Instead of minimizing the observed training error, SVR_poly and SVR_rbf attempt to minimize the generalization error bound so as to achieve generalized performance. The experimental results show that an improvement in predictive accuracy and capability of generalization can be achieved by the SVR_rbf approach in compare to SVR_poly soft computing methodology.

Simultaneous Determination of Metformin, Glipizide, Repaglinide, and Glimepiride or Metformin and Pioglitazone by a Validated LC Method: Application in the Presence of Metformin Impurity (1-Cyanoguanidine).

PubMed

El-Zaher, Asmaa A; Elkady, Ehab F; Elwy, Hanan M; Saleh, Mahmoud A

2016-07-01

A rapid, simple, and precise RPLC method was developed for the simultaneous determination of the widely used oral antidiabetic, metformin hydrochloride (MTF), with some commonly coadministered oral antidiabetics from different pharmacological classes-glipizide (GPZ), pioglitazone hydrochloride (PGZ), glimepiride (GLM), and repaglinide (RPG)-in bulk, laboratory-prepared mixtures and pharmaceutical formulations in the presence of metformin-reported impurity [1-cyanoguanidine (CNG)]. Chromatographic separation was achieved using isocratic elution mode with a mobile phase of acetonitrile: 0.02 M potassium dihydrogen phosphate (pH 3.17; 50-50, v/v) flowing through a CN Phenomenex column (Phenosphere Next, 250 × 4.6 mm, 5 μm) at a rate of 1.5 mL/min at ambient temperature. UV detection was carried out at 220 nm. The method was validated according to International Conference on Harmonization guidelines. Linearity, accuracy, and precision were satisfactory for concentration ranges: 0.175-350 μg/mL for MTF, 0.0525-105 μg/mL for GPZ, 0.125-250 μg/mL for PGZ, and 0.05-100 μg/mL for GLM and RPG. Correlation coefficients were >0.99 for all analytes. LOQs were 0.009 μg/mL for MTF, 0.009 μg/mL for GPZ, 0.04 μg/mL for GLM, 0.124 μg/mL for PGZ, and 0.044 μg/mL for RPG. The developed method is specific, accurate, and suitable for the QC and routine analysis of the cited drugs in their pharmaceutical products.

A distance-driven deconvolution method for CT image-resolution improvement

NASA Astrophysics Data System (ADS)

Han, Seokmin; Choi, Kihwan; Yoo, Sang Wook; Yi, Jonghyon

2016-12-01

The purpose of this research is to achieve high spatial resolution in CT (computed tomography) images without hardware modification. The main idea is to consider geometry optics model, which can provide the approximate blurring PSF (point spread function) kernel, which varies according to the distance from the X-ray tube to each point. The FOV (field of view) is divided into several band regions based on the distance from the X-ray source, and each region is deconvolved with a different deconvolution kernel. As the number of subbands increases, the overshoot of the MTF (modulation transfer function) curve increases first. After that, the overshoot begins to decrease while still showing a larger MTF than the normal FBP (filtered backprojection). The case of five subbands seems to show balanced performance between MTF boost and overshoot minimization. It can be seen that, as the number of subbands increases, the noise (STD) can be seen to show a tendency to decrease. The results shows that spatial resolution in CT images can be improved without using high-resolution detectors or focal spot wobbling. The proposed algorithm shows promising results in improving spatial resolution while avoiding excessive noise boost.

Measurements of ocean wave spectra and modulation transfer function with the airborne two frequency scatterometer

NASA Technical Reports Server (NTRS)

Weissman, D. E.; Johnson, J. W.

1984-01-01

The directional spectrum and the microwave modulation transfer function of ocean waves can be measured with the airborne two frequency scatterometer technique. Similar to tower based observations, the aircraft measurements of the Modulation Transfer Function (MTF) show that it is strongly affected by both wind speed and sea state. Also detected are small differences in the magnitudes of the MTF between downwind and upwind radar look directions, and variations with ocean wavenumber. The MTF inferred from the two frequency radar is larger than that measured using single frequency, wave orbital velocity techniques such as tower based radars or ROWS measurements from low altitude aircraft. Possible reasons for this are discussed. The ability to measure the ocean directional spectrum with the two frequency scatterometer, with supporting MTF data, is demonstrated.

Measurements of ocean wave spectra and modulation transfer function with the airborne two-frequency scatterometer

NASA Technical Reports Server (NTRS)

Weissman, D. E.; Johnson, J. W.

1986-01-01

The directional spectrum and the microwave modulation transfer function of ocean waves can be measured with the airborne two frequency scatterometer technique. Similar to tower based observations, the aircraft measurements of the Modulation Transfer Function (MTF) show that it is strongly affected by both wind speed and sea state. Also detected are small differences in the magnitudes of the MTF between downwind and upwind radar look directions, and variations with ocean wavenumber. The MTF inferred from the two frequency radar is larger than that measured using single frequency, wave orbital velocity techniques such as tower based radars or ROWS measurements from low altitude aircraft. Possible reasons for this are discussed. The ability to measure the ocean directional spectrum with the two frequency scatterometer, with supporting MTF data, is demonstrated.

Spatial Resolution Characterization for QuickBird Image Products 2003-2004 Season

NASA Technical Reports Server (NTRS)

Blonski, Slawomir

2006-01-01

This presentation focuses on spatial resolution characterization for QuickBird panochromatic images in 2003-2004 and presents data measurements and analysis of SSC edge target deployment and edge response extraction and modeling. The results of the characterization are shown as values of the Modulation Transfer Function (MTF) at the Nyquist spatial frequency and as the Relative Edge Response (RER) components. The results show that RER is much less sensitive to accuracy of the curve fitting than the value of MTF at Nyquist frequency. Therefore, the RER/edge response slope is a more robust estimator of the digital image spatial resolution than the MTF. For the QuickBird panochromatic images, the RER is consistently equal to 0.5 for images processed with the Cubic Convolution resampling and to 0.8 for the MTF resampling.

Monocyte B7 and Sialyl Lewis X modulates the efficacy of IL-10 down-regulation of LPS-induced monocyte tissue factor in whole blood.

PubMed

Warnes, G; Biggerstaff, J P; Francis, J L

1998-07-01

Recent studies have investigated the use of anti-inflammatory cytokine, interleukin 10 (IL-10) to control the development of disseminated intravascular coagulation (DIC) in sepsis by down-regulation of monocyte tissue factor (MTF) induced by lipopolysaccharide (LPS) in the initial phase of the disease. In vitro and in vivo human studies have shown that a minimal (<1 h) delay in IL-10 treatment significantly reduces the cytokines ability to inhibit LPS-induced MTF expression and the end products of coagulation. In this whole blood in vitro study we investigated the role of lymphocyte and platelet interactions with monocytes to up-regulate MTF expression in the presence of IL-10 in the initial phase of exposure to LPS. Individual blockade of monocyte B7 or platelet P-selectin significantly (35%) reduced MTF expression (P<0.05). IL-10 showed a dose-dependent inhibition of LPS (0.1 microg/ml) induced MTF expression, with 56% inhibition at 1 ng/ml, maximizing at 5 ng/ml IL-10 (75%; P<0.05). Simultaneous exposure to LPS and IL-10 (1 ng/ml) or addition of IL-10 1 h after LPS, with individual B7 and P-selectin blockade significantly enhanced the inhibition of MTF expression by IL-10 (P<0.05). We conclude that the efficacy of IL-10 to control DIC could be enhanced by a simultaneous B7 and P-selectin blockade.

Autogynephilia: an underappreciated paraphilia.

PubMed

Lawrence, Anne A

2011-01-01

Autogynephilia is defined as a male's propensity to be sexually aroused by the thought of himself as a female. It is the paraphilia that is theorized to underlie transvestism and some forms of male-to-female (MtF) transsexualism. Autogynephilia encompasses sexual arousal with cross-dressing and cross-gender expression that does not involve women's clothing per se. The concept of autogynephilia defines a typology of MtF transsexualism and offers a theory of motivation for one type of MtF transsexualism. Autogynephilia resembles a sexual orientation in that it involves elements of idealization and attachment as well as erotic desire. Nearly 3% of men in Western countries may experience autogynephilia; its most severe manifestation, MtF transsexualism, is rare but increasing in prevalence. Some theorists and clinicians reject the transsexual typology and theory of motivation derived from autogynephilia; their objections suggest a need for additional research. The concept of autogynephilia can assist clinicians in understanding some otherwise puzzling manifestations of nonhomosexual MtF transsexualism. Autogynephilia exemplifies an unusual paraphilic category called 'erotic target identity inversions', in which men desire to impersonate or turn their bodies into facsimiles of the persons or things to which they are sexually attracted. Copyright © 2011 S. Karger AG, Basel.

Onboard TDI stage estimation and calibration using SNR analysis

NASA Astrophysics Data System (ADS)

Haghshenas, Javad

2017-09-01

Electro-Optical design of a push-broom space camera for a Low Earth Orbit (LEO) remote sensing satellite is performed based on the noise analysis of TDI sensors for very high GSDs and low light level missions. It is well demonstrated that the CCD TDI mode of operation provides increased photosensitivity relative to a linear CCD array, without the sacrifice of spatial resolution. However, for satellite imaging, in order to utilize the advantages which the TDI mode of operation offers, attention should be given to the parameters which affect the image quality of TDI sensors such as jitters, vibrations, noises and etc. A predefined TDI stages may not properly satisfy image quality requirement of the satellite camera. Furthermore, in order to use the whole dynamic range of the sensor, imager must be capable to set the TDI stages in every shots based on the affecting parameters. This paper deals with the optimal estimation and setting the stages based on tradeoffs among MTF, noises and SNR. On-board SNR estimation is simulated using the atmosphere analysis based on the MODTRAN algorithm in PcModWin software. According to the noises models, we have proposed a formulation to estimate TDI stages in such a way to satisfy the system SNR requirement. On the other hand, MTF requirement must be satisfy in the same manner. A proper combination of both parameters will guaranty the full dynamic range usage along with the high SNR and image quality.

Hi-Res scan mode in clinical MDCT systems: Experimental assessment of spatial resolution performance.

PubMed

Cruz-Bastida, Juan P; Gomez-Cardona, Daniel; Li, Ke; Sun, Heyi; Hsieh, Jiang; Szczykutowicz, Timothy P; Chen, Guang-Hong

2016-05-01

The introduction of a High-Resolution (Hi-Res) scan mode and another associated option that combines Hi-Res mode with the so-called High Definition (HD) reconstruction kernels (referred to as a Hi-Res/HD mode in this paper) in some multi-detector CT (MDCT) systems offers new opportunities to increase spatial resolution for some clinical applications that demand high spatial resolution. The purpose of this work was to quantify the in-plane spatial resolution along both the radial direction and tangential direction for the Hi-Res and Hi-Res/HD scan modes at different off-center positions. A technique was introduced and validated to address the signal saturation problem encountered in the attempt to quantify spatial resolution for the Hi-Res and Hi-Res/HD scan modes. Using the proposed method, the modulation transfer functions (MTFs) of a 64-slice MDCT system (Discovery CT750 HD, GE Healthcare) equipped with both Hi-Res and Hi-Res/HD modes were measured using a metal bead at nine different off-centered positions (0-16 cm with a step size of 2 cm); at each position, both conventional scans and Hi-Res scans were performed. For each type of scan and position, 80 repeated acquisitions were performed to reduce noise induced uncertainties in the MTF measurements. A total of 15 reconstruction kernels, including eight conventional kernels and seven HD kernels, were used to reconstruct CT images of the bead. An ex vivo animal study consisting of a bone fracture model was performed to corroborate the MTF results, as the detection of this high-contrast and high frequency task is predominantly determined by spatial resolution. Images of this animal model generated by different scan modes and reconstruction kernels were qualitatively compared with the MTF results. At the centered position, the use of Hi-Res mode resulted in a slight improvement in the MTF; each HD kernel generated higher spatial resolution than its counterpart conventional kernel. However, the MTF along the tangential direction of the scan field of view (SFOV) was significantly degraded at off-centered positions, yet the combined Hi-Res/HD mode reduced this azimuthal MTF degradation. Images of the animal bone fracture model confirmed the improved spatial resolution at the off-centered positions through the use of the Hi-Res mode and HD kernels. The Hi-Res/HD scan improve spatial resolution of MDCT systems at both centered and off-centered positions.

Evaluation of Mean Glandular Dose and Modulation Transfer Function for Different Tube Potentials and Target-Filter Combinations in Computed Radiography Mammography

PubMed Central

Abdul Aziz,, Siti Aishah; Mohd Saparudin, Abdul Khaliq; Harun, Ahmad Zaky

2013-01-01

Background: Different target-filter combinations in computed radiography have different impacts on the dose and image quality in digital radiography. This study aims to evaluate the mean glandular dose (MGD) and modulation transfer function (MTF) of various target-filter combinations by investigating the signal intensities of X-ray beams. Methods: General Electric (GE) Senographe DMR Plus mammography unit was used for MGD and MTF evaluation. The measured MGD was compared with the dose reference level (DRL), whereas the MTF was evaluated using ImageJ 1.46o software. A modified Mammography Accreditation Phantom RMI 156 was exposed using different target-filter combinations of molybdenum-molybdenum (Mo-Mo), molybdenum-rhodium (Mo-Rh) and rhodium-rhodium (Rh-Rh) at two different tube voltages, 26 kV and 32 kV with 50 mAs. Results: In the MGD evaluations, all target-filters gave an MGD value of < 1.5 mGy. The one-way ANOVA test showed a highly significant interaction between the MGD and the kilovoltage and target-filter material used (26 kV: F (2,12) = 49,234, P = 0.001;32 kV: F (2,12) = 89,972, P = 0.001). A Tukey post-hoc test revealed that the MGD for 26 kV and 32 kV was highly affected by the target-filter combinations. The test of homogeneity of variances indicates that the MGD varies significantly for 26 kV and 32 kV images (0.045 and 0.030 (P < 0.05), respectively). However, the one-way ANOVA for the MTF shows that no significant difference exists between the target-filter combinations used with 26 kV and 32 kV images either in parallel or perpendicular to the chest wall side F (2,189) = 0.26, P > 0.05). Conclusion: Higher tube voltage and atomic number target-filter yield higher MGD values. However, the MTF is independent of the X-ray energy and the type of target-filter combinations used. PMID:23966821

Zinc-induced Dnmt1 expression involves antagonism between MTF-1 and nuclear receptor SHP

PubMed Central

Zhang, Yuxia; Andrews, Glen K.; Wang, Li

2012-01-01

Dnmt1 is frequently overexpressed in cancers, which contributes significantly to cancer-associated epigenetic silencing of tumor suppressor genes. However, the mechanism of Dnmt1 overexpression remains elusive. Herein, we elucidate a pathway through which nuclear receptor SHP inhibits zinc-dependent induction of Dnmt1 by antagonizing metal-responsive transcription factor-1 (MTF-1). Zinc treatment induces Dnmt1 transcription by increasing the occupancy of MTF-1 on the Dnmt1 promoter while decreasing SHP expression. SHP in turn represses MTF-1 expression and abolishes zinc-mediated changes in the chromatin configuration of the Dnmt1 promoter. Dnmt1 expression is increased in SHP-knockout (sko) mice but decreased in SHP-transgenic (stg) mice. In human hepatocellular carcinoma (HCC), increased DNMT1 expression is negatively correlated with SHP levels. Our study provides a molecular explanation for increased Dnmt1 expression in HCC and highlights SHP as a potential therapeutic target. PMID:22362755

Saturn Apollo Program

NASA Image and Video Library

1967-01-01

This photograph is a view of the Saturn V S-IC-5 (first) flight stage being hoisted into the S-IC-B1 test stand at the Mississippi Test Facility (MTF), Bay St. Louis, Mississippi. Begirning operations in 1966, the MTF has two test stands, a dual-position structure for running the S-IC stage at full throttle, and two separate stands for the S-II (Saturn V third) stage. It became the focus of the static test firing program. The completed S-IC stage was shipped from Michoud Assembly Facility (MAF) to the MTF. The stage was then installed into the 124-meter-high test stand for static firing tests before shipment to the Kennedy Space Center for final assembly of the Saturn V vehicle. The MTF was renamed to the National Space Technology Laboratory (NSTL) in 1974 and later to the Stennis Space Center (SSC) in May 1988.

Saturn Apollo Program

NASA Image and Video Library

1967-01-01

This photograph is a view of the Saturn V S-IC (first) test stage being hoisted into the S-IC-B1 test stand at the Mississippi Test Facility (MTF), Bay St. Louis, Mississippi. This stage was used to prove the operational readiness of the stand. Begirning operations in 1966, the MTF has two test stands; a dual-position structure for running the S-IC stage at full throttle, and two separate stands for the S-II (Saturn V third) stage. It became the focus of the static test firing program. The completed S-IC stage was shipped from the Michoud Assembly Facility (MAF) to the MTF. The stage was then installed into the 124-meter-high test stand for static firing tests before shipment to the Kennedy Space Center for final assembly of the Saturn V vehicle. The MTF was renamed to the National Space Technology Laboratory (NSTL) in 1974 and later to the Stennis Space Center (SSC) in May 1988.

Saturn Apollo Program

NASA Image and Video Library

1967-08-01

This photograph is a view of the Saturn V S-IC-5 (first) flight stage static test firing at the S-IC-B1 test stand at the Mississippi Test Facility (MTF), Bay St. Louis, Mississippi. Begirning operations in 1966, the MTF has two test stands, a dual-position structure for running the S-IC stage at full throttle, and two separate stands for the S-II (Saturn V third) stage. It became the focus of the static test firing program. The completed S-IC stage was shipped from Michoud Assembly Facility (MAF) to the MTF. The stage was then installed into the 407-foot-high test stand for the static firing tests before shipment to the Kennedy Space Center for final assembly of the Saturn V vehicle. The MTF was renamed to the National Space Technology Laboratory (NSTL) in 1974 and later to the Stennis Space Center (SSC) in May 1988.

HIV Prevalence and Risk Behaviors in Male to Female (MTF) Transgender Persons in Tijuana, Mexico.

PubMed

Salas-Espinoza, Kristian Jesús; Menchaca-Diaz, Rufino; Patterson, Thomas L; Urada, Lianne A; Smith, Davey; Strathdee, Steffanie A; Pitpitan, Eileen V

2017-12-01

Compared to HIV research on men who have sex with men, less is known about the risks and vulnerabilities for HIV among Male to Female (MTF) transgender persons, particularly in different geographic regions like Mexico. In Tijuana, Mexico, a border city experiencing a dynamic HIV epidemic, no precedent data exists on the MTF transgender population. Our aims were to estimate HIV prevalence and examine the behaviors and characteristics of the population. We conducted a cross-sectional study of 100 MTF transgender persons recruited through time location sampling in 2012. Participants underwent interviewer-administered (paper and pen) surveys and rapid tests for HIV. Descriptive univariate analyses were conducted on various factors, including sociodemographics, substance use, accessing social services (requested vs. received), stigma, and sex behaviors. A total of 22% tested positive for HIV, a prevalence higher than other key populations at risk for HIV in Tijuana.

Mental health of transgender youth in care at an adolescent urban community health center: A matched retrospective cohort study

PubMed Central

Reisner, Sari L.; Vetters, Ralph; Leclerc, M; Zaslow, Shayne; Wolfrum, Sarah; Shumer, Daniel; Mimiaga, Matthew J.

2014-01-01

Purpose Transgender youth represent a vulnerable population at risk for negative mental health outcomes including depression, anxiety, self-harm, and suicidality. Limited data exists to compare the mental health of transgender adolescents and emerging adults to cisgender youth accessing community-based clinical services; the current study aimed to fill this gap. Methods A retrospective cohort study of electronic health record (EHR) data from 180 transgender patients age 12–29 years seen between 2002–2011 at a Boston-based community health center was performed. The 106 female-to-male (FTM) and 74 male-to-female (MTF) patients were matched on gender identity, age, visit date, and race/ethnicity to cisgender controls. Mental health outcomes were extracted and analyzed using conditional logistic regression models. Logistic regression models compared FTM to MTF youth on mental health outcomes. Results The sample (n=360) had a mean age of 19.6 (SD=3.0); 43% white, 33% racial/ethnic minority, and 24% race/ethnicity unknown. Compared to cisgender matched controls, transgender youth had a two- to three-fold increased risk of depression, anxiety disorder, suicidal ideation, suicide attempt, self-harm without lethal intent, and both inpatient and outpatient mental health treatment (all p<0.05). No statistically significant differences in mental health outcomes were observed comparing FTM and MTF patients, adjusting for age, race/ethnicity, and hormone use. Conclusions Transgender youth were found to have a disparity in negative mental health outcomes compared to cisgender youth, with equally high burden in FTM and MTF patients. Identifying gender identity differences in clinical settings and providing appropriate services and supports are important steps in addressing this disparity. PMID:25577670

A cross-platform survey of CT image quality and dose from routine abdomen protocols and a method to systematically standardize image quality

PubMed Central

Favazza, Christopher P.; Duan, Xinhui; Zhang, Yi; Yu, Lifeng; Leng, Shuai; Kofler, James M.; Bruesewitz, Michael R.; McCollough, Cynthia H.

2015-01-01

Through this investigation we developed a methodology to evaluate and standardize CT image quality from routine abdomen protocols across different manufacturers and models. The influence of manufacturer-specific automated exposure control systems on image quality was directly assessed to standardize performance across a range of patient sizes. We evaluated 16 CT scanners across our health system, including Siemens, GE, and Toshiba models. Using each practice’s routine abdomen protocol, we measured spatial resolution, image noise, and scanner radiation output (CTDIvol). Axial and in-plane spatial resolutions were assessed through slice sensitivity profile (SSP) and modulation transfer function (MTF) measurements, respectively. Image noise and CTDIvol values were obtained for three different phantom sizes. SSP measurements demonstrated a bimodal distribution in slice widths: an average of 6.2 ± 0.2 mm using GE’s “Plus” mode reconstruction setting and 5.0 ± 0.1 mm for all other scanners. MTF curves were similar for all scanners. Average spatial frequencies at 50%, 10%, and 2% MTF values were 3.24 ± 0.37, 6.20 ± 0.34, and 7.84 ± 0.70 lp/cm, respectively. For all phantom sizes, image noise and CTDIvol varied considerably: 6.5–13.3 HU (noise) and 4.8–13.3 mGy (CTDIvol) for the smallest phantom; 9.1–18.4 HU and 9.3–28.8 mGy for the medium phantom; and 7.8–23.4 HU and 16.0–48.1 mGy for the largest phantom. Using these measurements and benchmark SSP, MTF, and image noise targets, CT image quality can be standardized across a range of patient sizes. PMID:26459751

Effects of intraocular lenses with different diopters on chromatic aberrations in human eye models.

PubMed

Song, Hui; Yuan, Xiaoyong; Tang, Xin

2016-01-11

In this study, the effects of intraocular lenses (IOLs) with different diopters (D) on chromatic aberration were investigated in human eye models, and the influences of the central thickness of IOLs on chromatic aberration were compared. A Liou-Brennan-based IOL eye model was constructed using ZEMAX optical design software. Spherical IOLs with different diopters (AR40e, AMO Company, USA) were implanted; modulation transfer function (MTF) values at 3 mm of pupil diameter and from 0 to out-of-focus blur were collected and graphed. MTF values, measured at 555 nm of monochromatic light under each spatial frequency, were significantly higher than the values measured at 470 to 650 nm of polychromatic light. The influences of chromatic aberration on MTF values decreased with the increase in IOL diopter when the spatial frequency was ≤12 c/d, while increased effects were observed when the spatial frequency was ≥15 c/d. The MTF values of each IOL eye model were significantly lower than the MTF values of the Liou-Brennan eye models when measured at 555 nm of monochromatic light and at 470 to 650 nm of polychromatic light. The MTF values were also found to be increased with the increase in IOL diopter. With higher diopters of IOLs, the central thickness increased accordingly, which could have created increased chromatic aberration and decreased the retinal image quality. To improve the postoperative visual quality, IOLs with lower chromatic aberration should be selected for patients with short axial lengths.

MONITORING THE FUTURE (MTF) SURVEY

EPA Science Inventory

Monitoring The Future (MTF) is an ongoing study of the behaviors, attitudes, and values of American secondary school students, college students, and young adults, conducted by the University of Michigan's Institute for Social Research and funded by the National Institute on Drug ...

Comparison of Double-Freeze versus Modified Triple-Freeze Pulmonary Cryoablation and Hemorrhage Volume Using Different Probe Sizes in an In Vivo Porcine Lung.

PubMed

Pan, Patrick J; Bansal, Anshuman K; Genshaft, Scott J; Kim, Grace H; Suh, Robert D; Abtin, Fereidoun

2018-05-01

To determine size of ablation zone and pulmonary hemorrhage in double-freeze (DF) vs modified triple-freeze (mTF) cryoablation protocols with different probe sizes in porcine lung. In 10 healthy adult pigs, 20 pulmonary cryoablations were performed using either a 2.4-mm or a 1.7-mm probe. Either conventional DF or mTF protocol was used. Serial noncontrast CT scans were performed during ablations. Ablation iceball and hemorrhage volumes were measured and compared between protocols and probe sizes. With 1.7-mm probe, greater peak iceball volume was observed with DF compared with mTF, although difference was not statistically significant (16.1 mL ± 1.9 vs 8.8 mL ± 3.6, P = .07). With 2.4-mm probe, DF and mTF produced similar peak iceball volumes (14.0 mL ± 2.8 vs 14.6 mL ± 2.7, P = .88). Midcycle hemorrhage was significantly larger with DF with the 1.7-mm probe (94.3 mL ± 22.2 vs 19.6 mL ± 2.1, P = .02) and with both sizes combined (93.2 mL ± 17.5 vs. 50.9 mL ± 12.6, P = .048). Rate of hemorrhage increase was significantly higher in DF (10.4 mL/min vs 5.1 mL/min, P = .003). End-cycle hemorrhage was visibly larger in DF compared with mTF across probe sizes, although differences were not statistically significant (P = .14 for 1.7 mm probe, P = .18 for 2.4 mm probe, and P = .07 for both probes combined). Rate of increase in hemorrhage during the last thaw period was not statistically different between DF and mTF (3.0 mL/min vs 2.8 mL/min, P = .992). mTF reduced rate of midcycle hemorrhage compared with DF. With mTF, midcycle hemorrhage was significantly smaller with 1.7-mm probe; although noticeably smaller with 2.4-mm probe, statistical significance was not achieved. Iceball size was not significantly different across both protocols and probe types. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

Sociodemographic Study of Danish Individuals Diagnosed with Transsexualism.

PubMed

Simonsen, Rikke; Hald, Gert Martin; Giraldi, Annamaria; Kristensen, Ellids

2015-06-01

Male-to-female (MtF) and female-to-male (FtM) individuals with transsexualism (International Classification of Diseases-10) may differ in core clinical and sociodemographic variables such as age, sexual orientation, marriage and parenthood, school, educational level, and employment. Assessing and understanding the implication of such differences may be a key to developing appropriate and effective treatment and intervention strategies for this group. However, research in the area remains sparse and is often on small populations, making the generalization of results from current studies on individuals diagnosed with transsexualism difficult. (i) To describe and assess key sociodemographic and treatment-related differences between MtF and FtM individuals in a Danish population of individuals diagnosed with transsexualism; (ii) to assess possible implications of such difference, if any, for clinical treatment initiatives for individuals diagnosed with transsexualism. Follow-up of 108 individuals who had permission to undergo sex reassignment surgery (SRS, meaning castration and genital plastic surgery) over a 30-year period from 1978 to 2008 through the Gender Identity Unit in Copenhagen, Denmark. The individuals were identified through Social Security numbers. Clinical and sociodemographic data from medical records were collected. The sex ratio was 1.16:1 (MtF : FtM). Mean age at first referral was 26.9 (standard deviation [SD] 8.8) years for FtM and 30.2 (SD 9.7) for MtF individuals. Compared with MtF, FtM had a significantly lower onset age (before 12 years of age) and lower age when permission for SRS was granted. Further, FtM individuals were significantly more often gynephilic (sexually attracted to females) during research period and less likely to start self-initiated hormonal sex reassignment (SR) (treatment with cross-sex hormones). The MtF and FtM groups did not differ in years of school, educational level, employment, or engagement in marriage and cohabitation. As approximately half of MtF started cross-sex hormonal SR without attending a gender unit, future treatment needs to focus on this group of MtF individuals in order to accommodate the medical risks of self-initiated hormonal treatment.Earlier intervention with adolescents appears necessary since three-quarters of FtM individuals before age 12 had problems with their assigned sex. For both MtF and FtM, we found problems in areas of school, education, and employment and recommend further help in these core areas.

A Novel Method for Estimating Transgender Status Using Electronic Medical Records

PubMed Central

Roblin, Douglas; Barzilay, Joshua; Tolsma, Dennis; Robinson, Brandi; Schild, Laura; Cromwell, Lee; Braun, Hayley; Nash, Rebecca; Gerth, Joseph; Hunkeler, Enid; Quinn, Virginia P.; Tangpricha, Vin; Goodman, Michael

2016-01-01

Background We describe a novel algorithm for identifying transgender people and determining their male-to-female (MTF) or female-to-male (FTM) identity in electronic medical records (EMR) of an integrated health system. Methods A SAS program scanned Kaiser Permanente Georgia EMR from January 2006 through December 2014 for relevant diagnostic codes, and presence of specific keywords (e.g., “transgender” or “transsexual”) in clinical notes. Eligibility was verified by review of de-identified text strings containing targeted keywords, and if needed, by an additional in-depth review of records. Once transgender status was confirmed, FTM or MTF identity was assessed using a second SAS program and another round of text string reviews. Results Of 813,737 members, 271 were identified as possibly transgender: 137 through keywords only, 25 through diagnostic codes only, and 109 through both codes and keywords. Of these individuals, 185 (68%, 95% confidence interval [CI]: 62-74%) were confirmed as definitely transgender. The proportions (95% CIs) of definite transgender status among persons identified via keywords, diagnostic codes, and both were 45% (37-54%), 56% (35-75%), and 100% (96-100%), respectively. Of the 185 definitely transgender people, 99 (54%, 95% CI: 46-61%) were MTF, 84 (45%, 95% CI: 38-53%) were FTM. For two persons, gender identity remained unknown. Prevalence of transgender people (per 100,000 members) was 4.4 (95% CI: 2.6-7.4) in 2006 and 38.7 (95% CI: 32.4-46.2) in 2014. Conclusions The proposed method of identifying candidates for transgender health studies is low cost and relatively efficient. It can be applied in other similar health care systems. PMID:26907539

NPP VIIRS Geometric Performance Status

NASA Technical Reports Server (NTRS)

Lin, Guoqing; Wolfe, Robert E.; Nishihama, Masahiro

2011-01-01

Visible Infrared Imager Radiometer Suite (VIIRS) instrument on-board the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) satellite is scheduled for launch in October, 2011. It is to provide satellite measured radiance/reflectance data for both weather and climate applications. Along with radiometric calibration, geometric characterization and calibration of Sensor Data Records (SDRs) are crucial to the VIIRS Environmental Data Record (EDR) algorithms and products which are used in numerical weather prediction (NWP). The instrument geometric performance includes: 1) sensor (detector) spatial response, parameterized by the dynamic field of view (DFOV) in the scan direction and instantaneous FOV (IFOV) in the track direction, modulation transfer function (MTF) for the 17 moderate resolution bands (M-bands), and horizontal spatial resolution (HSR) for the five imagery bands (I-bands); 2) matrices of band-to-band co-registration (BBR) from the corresponding detectors in all band pairs; and 3) pointing knowledge and stability characteristics that includes scan plane tilt, scan rate and scan start position variations, and thermally induced variations in pointing with respect to orbital position. They have been calibrated and characterized through ground testing under ambient and thermal vacuum conditions, numerical modeling and analysis. This paper summarizes the results, which are in general compliance with specifications, along with anomaly investigations, and describes paths forward for characterizing on-orbit BBR and spatial response, and for improving instrument on-orbit performance in pointing and geolocation.

Becoming what we love: autogynephilic transsexualism conceptualized as an expression of romantic love.

PubMed

Lawrence, Anne A

2007-01-01

The increasing prevalence of male-to-female (MtF) transsexualism in Western countries is largely due to the growing number of MtF transsexuals who have a history of sexual arousal with cross-dressing or cross-gender fantasy. Ray Blanchard proposed that these transsexuals have a paraphilia he called autogynephilia, which is the propensity to be sexually aroused by the thought or image of oneself as female. Autogynephilia defines a transsexual typology and provides a theory of transsexual motivation, in that Blanchard proposed that MtF transsexuals are either sexually attracted exclusively to men (homosexual) or are sexually attracted primarily to the thought or image of themselves as female (autogynephilic), and that autogynephilic transsexuals seek sex reassignment to actualize their autogynephilic desires. Despite growing professional acceptance, Blanchard's formulation is rejected by some MtF transsexuals as inconsistent with their experience. This rejection, I argue, results largely from the misconception that autogynephilia is a purely erotic phenomenon. Autogynephilia can more accurately be conceptualized as a type of sexual orientation and as a variety of romantic love, involving both erotic and affectional or attachment-based elements. This broader conception of autogynephilia addresses many of the objections to Blanchard's theory and is consistent with a variety of clinical observations concerning autogynephilic MtF transsexualism.

Benchmarking the performance of fixed-image receptor digital radiographic systems part 1: a novel method for image quality analysis.

PubMed

Lee, Kam L; Ireland, Timothy A; Bernardo, Michael

2016-06-01

This is the first part of a two-part study in benchmarking the performance of fixed digital radiographic general X-ray systems. This paper concentrates on reporting findings related to quantitative analysis techniques used to establish comparative image quality metrics. A systematic technical comparison of the evaluated systems is presented in part two of this study. A novel quantitative image quality analysis method is presented with technical considerations addressed for peer review. The novel method was applied to seven general radiographic systems with four different makes of radiographic image receptor (12 image receptors in total). For the System Modulation Transfer Function (sMTF), the use of grid was found to reduce veiling glare and decrease roll-off. The major contributor in sMTF degradation was found to be focal spot blurring. For the System Normalised Noise Power Spectrum (sNNPS), it was found that all systems examined had similar sNNPS responses. A mathematical model is presented to explain how the use of stationary grid may cause a difference between horizontal and vertical sNNPS responses.

A novel x-ray detector design with higher DQE and reduced aliasing: Theoretical analysis of x-ray reabsoprtion in detector converter material

NASA Astrophysics Data System (ADS)

Nano, Tomi; Escartin, Terenz; Karim, Karim S.; Cunningham, Ian A.

2016-03-01

The ability to improve visualization of structural information in digital radiography without increasing radiation exposures requires improved image quality across all spatial frequencies, especially at high frequencies. The detective quantum efficiency (DQE) as a function of spatial frequency quantifies image quality given by an x-ray detector. We present a method of increasing DQE at high spatial frequencies by improving the modulation transfer function (MTF) and reducing noise aliasing. The Apodized Aperature Pixel (AAP) design uses a detector with micro-elements to synthesize desired pixels and provide higher DQE than conventional detector designs. A cascaded system analysis (CSA) that incorporates x-ray interactions is used for comparison of the theoretical MTF, noise power spectrum (NPS), and DQE. Signal and noise transfer through the converter material is shown to consist of correlated an uncorrelated terms. The AAP design was shown to improve the DQE of both material types that have predominantly correlated transfer (such as CsI) and predominantly uncorrelated transfer (such as Se). Improvement in the MTF by 50% and the DQE by 100% at the sampling cut-off frequency is obtained when uncorrelated transfer is prevalent through the converter material. Optimizing high-frequency DQE results in improved image contrast and visualization of small structures and fine-detail.

Varied Reports of Adult Transgender Suicidality: Synthesizing and Describing the Peer-Reviewed and Gray Literature

PubMed Central

Adams, Noah; Hitomi, Maaya; Moody, Cherie

2017-01-01

Abstract Purpose: This article reports on the findings of a meta-synthesis undertaken on published gray transgender suicidality literature, to determine the average rate of suicidal ideation and attempts in this population. Methods: Studies included in this synthesis were restricted to the 42 that reported on 5 or more Canadian or U.S. adult participants, as published between 1997 and February 2016 in either gray or peer-reviewed health literature. Results: Across these 42 studies an average of 55% of respondents ideated about and 29% attempted suicide in their lifetimes. Within the past year, these averages were, respectively, 51% and 11%, or 14 and 22 times that of the general public. Overall, suicidal ideation was higher among individuals of a male-to-female (MTF) than female-to-male (FTM) alignment, and lowest among those who were gender non-conforming (GNC). Conversely, attempts occurred most often among FTM individuals, then decreased for MTF individuals, followed by GNC individuals. Conclusion: These findings may be useful in creating targeted interventions that take into account both the alarmingly high rate of suicidality in this population, and the relatively differential experience of FTM, MTF, and GNC individuals. Future research should examine minority stress theory and suicidality protection/resilience factors, particularly transition, on this population. PMID:28861548

Measuring the spatial resolution of an optical system in an undergraduate optics laboratory

NASA Astrophysics Data System (ADS)

Leung, Calvin; Donnelly, T. D.

2017-06-01

Two methods of quantifying the spatial resolution of a camera are described, performed, and compared, with the objective of designing an imaging-system experiment for students in an undergraduate optics laboratory. With the goal of characterizing the resolution of a typical digital single-lens reflex (DSLR) camera, we motivate, introduce, and show agreement between traditional test-target contrast measurements and the technique of using Fourier analysis to obtain the modulation transfer function (MTF). The advantages and drawbacks of each method are compared. Finally, we explore the rich optical physics at work in the camera system by calculating the MTF as a function of wavelength and f-number. For example, we find that the Canon 40D demonstrates better spatial resolution at short wavelengths, in accordance with scalar diffraction theory, but is not diffraction-limited, being significantly affected by spherical aberration. The experiment and data analysis routines described here can be built and written in an undergraduate optics lab setting.

Viral hepatitis screening in transgender patients undergoing gender identity hormonal therapy.

PubMed

Mangla, Neeraj; Mamun, Rifat; Weisberg, Ilan S

2017-11-01

Viral hepatitis is a global health issue and can lead to cirrhosis, liver failure, and hepatocellular carcinoma. Guidelines for viral hepatitis screening in the transgender population do not exist. Transgender patients may be at higher risk for contracting viral hepatitis due to socioeconomic and behavioral factors. The aim of this study was to measure the quality of screening, prevalence, and susceptibility of viral hepatitis, and to identify barriers to screening in transgender patients undergoing gender identity hormonal therapy. LGBTQ-friendly clinic visits from transgender patients older than 18 years in New York City from 2012 to 2015 were reviewed. Approximately 13% of patients were screened for any viral hepatitis on initial consultation. Screening rates for hepatitis C virus (HCV), hepatitis B virus (HBV), and hepatitis A virus (HAV) at any point were 27, 22, and 20%. HAV screening was performed in 28% of the female to male (FtM) patients and 16% of male to female (MtF) (P<0.05) patients. HBV screening was performed in 30% of FtM patients and 18% of MtF patients (P<0.05). Thirty-one percent of FtM, 24% of MtF, and 17% of genderqueer patients were tested for HCV (P>0.05). Prevalence of HCV, HBV, and HIV in FtM was 0, 0, and 0.44% and that in MtF was 1.78, 0.89, and 1.78%, respectively. Percentage of patients immune to hepatitis A in FtM and MtF subgroups were 55 and 47% (P>0.05). Percentage of patients immune to HBV in FtM and MtF subgroups were 54 and 48% (P>0.05). This study indicates a significant lack of hepatitis screening in the transgender population and a concerning proportion of patients susceptible to disease.

Similar response patterns to topical minoxidil foam 5% in frontal and vertex scalp of men with androgenetic alopecia: a microarray analysis.

PubMed

Mirmirani, P; Consolo, M; Oyetakin-White, P; Baron, E; Leahy, P; Karnik, P

2015-06-01

There are regional variations in the scalp hair miniaturization seen in androgenetic alopecia (AGA). Use of topical minoxidil can lead to reversal of miniaturization in the vertex scalp. However, its effects on other scalp regions have been less well studied. To determine whether scalp biopsies from men with AGA show variable gene expression before and after 8 weeks of treatment with minoxidil topical foam 5% (MTF) vs. placebo. A placebo-controlled double-blinded prospective pilot study of MTF vs. placebo was conducted in 16 healthy men aged 18-49 years with Hamilton-Norwood type IV-V thinning. The subjects were asked to apply the treatment (active drug or placebo) to the scalp twice daily for 8 weeks. Stereotactic scalp photographs were taken at the baseline and final visits, to monitor global hair growth. Scalp biopsies were taken at the leading edge of hair loss from the frontal and vertex scalp before and after treatment with MTF and placebo, and microarray analysis was performed using the Affymetrix GeneChip HG U133 Plus 2.0. Global stereotactic photographs showed that MTF induced hair growth in both the frontal and vertex scalp of patients with AGA. Regional differences in gene expression profiles were observed before treatment. However, MTF treatment induced the expression of hair keratin-associated genes and decreased the expression of epidermal differentiation complex and inflammatory genes in both scalp regions. These data suggest that MTF is effective in the treatment of both the frontal and vertex scalp of patients with AGA. © 2014 British Association of Dermatologists.

Association study of ERβ, AR, and CYP19A1 genes and MtF transsexualism.

PubMed

Fernández, Rosa; Esteva, Isabel; Gómez-Gil, Esther; Rumbo, Teresa; Almaraz, Mari Cruz; Roda, Ester; Haro-Mora, Juan-Jesús; Guillamón, Antonio; Pásaro, Eduardo

2014-12-01

The etiology of male-to-female (MtF) transsexualism is unknown. Both genetic and neurological factors may play an important role. To investigate the possible influence of the genetic factor on the etiology of MtF transsexualism. We carried out a cytogenetic and molecular analysis in 442 MtFs and 473 healthy, age- and geographical origin-matched XY control males. The karyotype was investigated by G-banding and by high-density array in the transsexual group. The molecular analysis involved three tandem variable regions of genes estrogen receptor β (ERβ) (CA tandem repeats in intron 5), androgen receptor (AR) (CAG tandem repeats in exon 1), and CYP19A1 (TTTA tandem repeats in intron 4). The allele and genotype frequencies, after division into short and long alleles, were obtained. We investigated the association between genotype and transsexualism by performing a molecular analysis of three variable regions of genes ERβ, AR, and CYP19A1 in 915 individuals (442 MtFs and 473 control males). Most MtFs showed an unremarkable 46,XY karyotype (97.96%). No specific chromosome aberration was associated with MtF transsexualism, and prevalence of aneuploidy (2.04%) was slightly higher than in the general population. Molecular analyses showed no significant difference in allelic or genotypic distribution of the genes examined between MtFs and controls. Moreover, molecular findings presented no evidence of an association between the sex hormone-related genes (ERβ, AR, and CYP19A1) and MtF transsexualism. The study suggests that the analysis of karyotype provides limited information in these subjects. Variable regions analyzed from ERβ, AR, and CYP19A1 are not associated with MtF transsexualism. Nevertheless, this does not exclude other polymorphic regions not analyzed. © 2014 International Society for Sexual Medicine.

[Therapeutic effect of metformin for clomiphene-resistant infertility patients with polycystic ovary syndrome: a systematic analysis].

PubMed

Wang, Ling-li; Ren, Wei; Cheng, Qing-feng; Fan, Xiao-dong

2012-09-01

To evaluate the efficacy of metformin (MTF) in treatment of clomiphene (CC)-resistant patients with polycystic ovary syndrome (PCOS). The published articles of randomized controlled trial (RCT) of comparison of MTF combined with CC and CC alone in treatment of CC-resistant PCOS were searched in PubMed, EMBASE, OVID, EBSCO databases and Cochrane Library, and these studies were screened under inclusion and exclusion criteria. The quality of included studies and extract data of comparison of ovulation rates and pregnancy rates were evaluated. And the Meta-analysis using statistic software RevMan 5.0 was completed. Total of 333 patients in total 8 trials were included. Meta analysis showed that MTF plus CC led to a significantly higher clinical ovulation rate (OR = 7.31, 95%CI: 2.57 - 20.76, P < 0.05) and pregnancy rate (OR = 7.93, 95%CI: 2.45 - 25.63, P < 0.05) than that of CC alone. MTF can increase ovulation and pregnancy rates of CC-resistant PCOS women.

Increased Cortical Thickness in Male-to-Female Transsexualism.

PubMed

Luders, Eileen; Sánchez, Francisco J; Tosun, Duygu; Shattuck, David W; Gaser, Christian; Vilain, Eric; Toga, Arthur W

2012-08-01

The degree to which one identifies as male or female has a profound impact on one's life. Yet, there is a limited understanding of what contributes to this important characteristic termed gender identity . In order to reveal factors influencing gender identity, studies have focused on people who report strong feelings of being the opposite sex, such as male-to-female (MTF) transsexuals. To investigate potential neuroanatomical variations associated with transsexualism, we compared the regional thickness of the cerebral cortex between 24 MTF transsexuals who had not yet been treated with cross-sex hormones and 24 age-matched control males. Results revealed thicker cortices in MTF transsexuals, both within regions of the left hemisphere (i.e., frontal and orbito-frontal cortex, central sulcus, perisylvian regions, paracentral gyrus) and right hemisphere (i.e., pre-/post-central gyrus, parietal cortex, temporal cortex, precuneus, fusiform, lingual, and orbito-frontal gyrus). These findings provide further evidence that brain anatomy is associated with gender identity, where measures in MTF transsexuals appear to be shifted away from gender-congruent men.

Structure and Function of the Glycopeptide N-methyltransferase MtfA, a Tool for the Biosynthesis of Modified Glycopeptide Antibiotics

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

Shi, Rong; Lamb, Sherry S.; Zakeri, Bijan

2009-06-01

There is a considerable interest in the modification of existing antibiotics to generate new antimicrobials. Glycopeptide antibiotics (GPAs) are effective against serious Gram-positive bacterial pathogens including methicillin-resistant Staphylococcus aureus. However, resistance to these antibiotics is becoming a serious problem requiring new strategies. We show that the Amycolatopsis orientalis (S)-adenosyl-L-methionine-dependent methyltransferase MtfA, from the vancomycin-class GPA chloroeremomycin biosynthetic pathway, catalyzes in vivo and in vitro methyl transfer to generate methylated GPA derivatives of the teicoplanin class. The crystal structure of MtfA complexed with (S)-adenosyl-L-methionine, (S)-adenosylhomocysteine, or sinefungin inhibitor, coupled with mutagenesis, identified His228 as a likely general base required for methylmore » transfer to the N terminus of the glycopeptide. Computational docking and molecular dynamics simulations were used to model binding of demethyl-vancomycin aglycone to MtfA. These results demonstrate its utility as a tool for engineering methylated analogs of GPAs.« less

Performance evaluation for pinhole collimators of small gamma camera by MTF and NNPS analysis: Monte Carlo simulation study

NASA Astrophysics Data System (ADS)

Jeon, Hosang; Kim, Hyunduk; Cha, Bo Kyung; Kim, Jong Yul; Cho, Gyuseong; Chung, Yong Hyun; Yun, Jong-Il

2009-06-01

Presently, the gamma camera system is widely used in various medical diagnostic, industrial and environmental fields. Hence, the quantitative and effective evaluation of its imaging performance is essential for design and quality assurance. The National Electrical Manufacturers Association (NEMA) standards for gamma camera evaluation are insufficient to perform sensitive evaluation. In this study, modulation transfer function (MTF) and normalized noise power spectrum (NNPS) will be suggested to evaluate the performance of small gamma camera with changeable pinhole collimators using Monte Carlo simulation. We simulated the system with a cylinder and a disk source, and seven different pinhole collimators from 1- to 4-mm-diameter pinhole with lead. The MTF and NNPS data were obtained from output images and were compared with full-width at half-maximum (FWHM), sensitivity and differential uniformity. In the result, we found that MTF and NNPS are effective and novel standards to evaluate imaging performance of gamma cameras instead of conventional NEMA standards.

Biological indicators for monitoring water quality of MTF canals system

NASA Technical Reports Server (NTRS)

Sethi, S. L.

1975-01-01

Biological models, diversity indexes, were developed to predict environmental effects of NASA's Mississippi test facility (MTF) chemical operations on canal systems in the area. To predict the effects on local streams, a physical model of unpolluted streams was established. The model is fed by artesian well water free of background levels of pollutants. The species diversity and biota composition of unpolluted MTF stream was determined; resulting information will be used to form baseline data for future comparisons. Biological modeling was accomplished by adding controlled quantities or kinds of chemical pollutants and evaluating the effects of these chemicals on the biological life of the stream.

Modulation transfer function measurement technique for small-pixel detectors

NASA Technical Reports Server (NTRS)

Marchywka, Mike; Socker, Dennis G.

1992-01-01

A modulation transfer function (MTF) measurement technique suitable for large-format, small-pixel detector characterization has been investigated. A volume interference grating is used as a test image instead of the bar or sine wave target images normally used. This technique permits a high-contrast, large-area, sinusoidal intensity distribution to illuminate the device being tested, avoiding the need to deconvolve raw data with imaging system characteristics. A high-confidence MTF result at spatial frequencies near 200 cycles/mm is obtained. We present results at several visible light wavelengths with a 6.8-micron-pixel CCD. Pixel response functions are derived from the MTF results.

Assessment of three dead detector correction methods for cone-beam computed tomography

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

Nelms, David W.; Shukla, Hemant I.; Nixon, Earl

Purpose: Dead detectors due to manufacturing defects or radiation damage in the electronic portal imaging devices (EPIDs) used for cone-beam computed tomography (CBCT) can lead to image degradation and ring artifacts. In this work three dead detector correction methods were assessed using megavoltage CBCT (MVCBCT) as a test system, with the goals of assessing the relative effectiveness of the three methods and establishing the conditions for which they fail. Methods: MVCBCT projections acquired with four linacs at 8 and 60 MU (monitor units) were degraded with varying percentages (2%-95%) of randomly distributed dead single detectors (RDSs), randomly distributed dead detectormore » clusters (RDCs) of 2 mm diameter, and nonrandomly distributed dead detector disks (NRDDs) of varying diameter (4-16 mm). Correction algorithms were bidirectional linear interpolation (BLI), quad-directional linear interpolation (QLI), and a Laplacian solution (LS) method. Correction method failure was defined to occur if ring artifacts were present in the reconstructed phantom images from any linac or if the modulation transfer function (MTF) for any linac dropped below baseline with a p value, calculated with the two sample t test, of less than 0.01. Results: All correction methods failed at the same or lower RDC/RDS percentages and NRDD diameters for the 60 MU as for the 8 MU cases. The LS method tended to outperform or match the BLI and QLI methods. If ring artifacts anywhere in the images were considered unacceptable, the LS method failed for 60 MU at >33% RDS, >2% RDC, and >4 mm NRDD. If ring artifacts within 4 mm longitudinally of the phantom section interfaces were considered acceptable, the LS method failed for 60 MU at >90% RDS, >80% RDC, and >4 mm NRDD. LS failed due to MTF drop for 60 MU at >50% RDS, >25% RDC, and >4 mm NRDD. Conclusions: The LS method is superior to the BLI and QLI methods, and correction algorithm effectiveness decreases as imaging dose increases. All correction methods failed first due to ring artifacts and second due to MTF drop. If ring artifacts in axial slices within a 4 mm longitudinal distance from phantom section interfaces are acceptable, statistically significant loss in spatial resolution does not occur until over 25% of the EPID is covered in randomly distributed dead detectors, or NRDDs of 4 mm diameter are present.« less

Laboratory-confirmed HIV and sexually transmitted infection seropositivity and risk behavior among sexually active transgender patients at an adolescent and young adult urban community health center.

PubMed

Reisner, Sari L; Vetters, Ralph; White, Jaclyn M; Cohen, Elijah L; LeClerc, M; Zaslow, Shayne; Wolfrum, Sarah; Mimiaga, Matthew J

2015-01-01

The sexual health of transgender adolescents and young adults who present for health care in urban community health centers is understudied. A retrospective review of electronic health record (EHR) data was conducted from 180 transgender patients aged 12-29 years seen for one or more health-care visits between 2001 and 2010 at an urban community health center serving youth in Boston, MA. Analyses were restricted to 145 sexually active transgender youth (87.3% of the sample). Laboratory-confirmed HIV and sexually transmitted infections (STIs) seroprevalence, demographics, sexual risk behavior, and structural and psychosocial risk indicators were extracted from the EHR. Analyses were descriptively focused for HIV and STIs. Stratified multivariable logistic regression models were fit for male-to-female (MTF) and female-to-male (FTM) patients separately to examine factors associated with any unprotected anal and/or vaginal sex (UAVS). The mean age was 20.0 (SD=2.9); 21.7% people of color, 46.9% white (non-Hispanic), 21.4% race/ethnicity unknown; 43.4% MTF, and 56.6% FTM; and 68.3% were on cross-sex hormones. Prevalence of STIs: 4.8% HIV, 2.8% herpes simplex virus, 2.8% syphilis, 2.1% chlamydia, 2.1% gonorrhea, 2.8% hepatitis C, 1.4% human papilloma virus. Only gonorrhea prevalence significantly differed by gender identity (MTF 2.1% vs. 0.0% FTM; p=0.046). Nearly half (47.6%) of the sample engaged in UAVS (52.4% MTF, 43.9% FTM, p=0.311). FTM more frequently had a primary sex partner compared to MTF (48.8% vs. 25.4%; p=0.004); MTF more frequently had a casual sex partner than FTM (69.8% vs. 42.7% p=0.001). In multivariable models, MTF youth who were younger in age, white non-Hispanic, and reported a primary sex partner had increased odds of UAVS; whereas, FTM youth reporting a casual sex partner and current alcohol use had increased odds of UAVS (all p<0.05). Factors associated with sexual risk differ for MTF and FTM youth. Partner type appears pivotal to understanding sexual risk in transgender adolescents and young adults. HIV and STI prevention efforts, including early intervention efforts, are needed in community-based settings serving transgender youth that attend to sex-specific (biological) and gender-related (social) pathways.

Effects of rubber shock absorber on the flywheel micro vibration in the satellite imaging system

NASA Astrophysics Data System (ADS)

Deng, Changcheng; Mu, Deqiang; Jia, Xuezhi; Li, Zongxuan

2016-12-01

When a satellite is in orbit, its flywheel will generate micro vibration and affect the imaging quality of the camera. In order to reduce this effect, a rubber shock absorber is used, and a numerical model and an experimental setup are developed to investigate its effect on the micro vibration in the study. An integrated model is developed for the system, and a ray tracing method is used in the modeling. The spot coordinates and displacements of the image plane are obtained, and the modulate transfer function (MTF) of the system is calculated. A satellite including a rubber shock absorber is designed, and the experiments are carried out. Both simulation and experiments results show that the MTF increases almost 10 %, suggesting the rubber shock absorber is useful to decrease the flywheel vibration.

Different mathematical processing of absorption, ratio and derivative spectra for quantification of mixtures containing minor component: An application to the analysis of the recently co-formulated antidiabetic drugs; canagliflozin and metformin

NASA Astrophysics Data System (ADS)

Lotfy, Hayam M.; Mohamed, Dalia; Elshahed, Mona S.

2018-01-01

In the presented work several spectrophotometric methods were performed for the quantification of canagliflozin (CGZ) and metformin hydrochloride (MTF) simultaneously in their binary mixture. Two of these methods; response correlation (RC) and advanced balance point-spectrum subtraction (ABP-SS) were developed and introduced for the first time in this work, where the latter method (ABP-SS) was performed on both the zero order and the first derivative spectra of the drugs. Besides, two recently established methods; advanced amplitude modulation (AAM) and advanced absorbance subtraction (AAS) were also accomplished. All the proposed methods were validated in accordance to the ICH guidelines, where all methods were proved to be accurate and precise. Additionally, the linearity range, limit of detection and limit of quantification were determined and the selectivity was examined through the analysis of laboratory prepared mixtures and the combined dosage form of the drugs. The proposed methods were capable of determining the two drugs in the ratio present in the pharmaceutical formulation CGZ:MTF (1:17) without the requirement of any preliminary separation, further dilution or standard spiking. The results obtained by the proposed methods were in compliance with the reported chromatographic method when compared statistically, proving the absence of any significant difference in accuracy and precision between the proposed and reported methods.

Stress-coping strategies of patients with gender identity disorder.

PubMed

Matsumoto, Yosuke; Sato, Toshiki; Ohnishi, Masaru; Kishimoto, Yuki; Terada, Seishi; Kuroda, Shigetoshi

2009-12-01

Previous research has not addressed gender differences in coping strategies among patients with gender identity disorder (GID). Nor has the relationship of coping strategies to other demographic characteristics ever been clarified in GID. In this study, we tried to clarify the relationship between stress-coping strategies and demographic characteristics among patients with GID. The coping strategies of 344 patients with GID [227 female-to-male (FTM) and 117 male-to-female (MTF)] were assessed using the Japanese version of the Ways of Coping Questionnaires, Lazarus Stress-coping Inventory. Comparison of the stress-coping inventory between MTF and FTM GID patients revealed that FTM GID patients were significantly more reliant on positive reappraisal strategies in stressful situations than MTF GID patients (P = 0.007). The difference in the usage of positive reappraisal strategies between MTF and FTM type GID patients was not explained by other demographic characteristics, and we suppose that the gender difference in GID patients might influence the usage of positive reappraisal strategies. The ratio of FTM GID patients might be higher at our center because MTF GID patients can obtain vaginoplasty easily, whereas phalloplasty surgery for FTM GID patients is performed at only a few centers, including our clinic, in Japan. As a result, more FTM GID patients come to our clinic with a clear intention to undergo sexual rearrangement surgery, which might influence the gender difference in using positive reappraisal.

Study of the Effects of Total Modulation Transfer Function Changes on Observer Performance Using Clinical Mammograms.

NASA Astrophysics Data System (ADS)

Bencomo, Jose Antonio Fagundez

The main goal of this study was to relate physical changes in image quality measured by Modulation Transfer Function (MTF) to diagnostic accuracy. One Hundred and Fifty Kodak Min-R screen/film combination conventional craniocaudal mammograms obtained with the Pfizer Microfocus Mammographic system were selected from the files of the Department of Radiology, at M.D. Anderson Hospital and Tumor Institute. The mammograms included 88 cases with a variety of benign diagnosis and 62 cases with a variety of malignant biopsy diagnosis. The average age of the patient population was 55 years old. 70 cases presented calcifications with 30 cases having calcifications smaller than 0.5mm. 46 cases presented irregular bordered masses larger than 1 cm. 30 cases presented smooth bordered masses with 20 larger than 1 cm. Four separated copies of the original images were made each having a different change in the MTF using a defocusing technique whereby copies of the original were obtained by light exposure through different thicknesses (spacing) of transparent film base. The mammograms were randomized, and evaluated by three experienced mammographers for the degree of visibility of various anatomical breast structures and pathological lesions (masses and calicifications), subjective image quality, and mammographic interpretation. 3,000 separate evaluations were anayzed by several statistical techniques including Receiver Operating Characteristic curve analysis, McNemar test for differences between proportions and the Landis et al. method of agreement weighted kappa for ordinal categorical data. Results from the statistical analysis show: (1) There were no statistical significant differences in the diagnostic accuracy of the observers when diagnosing from mammograms with the same MTF. (2) There were no statistically significant differences in diagnostic accuracy for each observer when diagnosing from mammograms with the different MTF's used in the study. (3) There statistical significant differences in detail visibility between the copies and the originals. Detail visibility was better in the originals. (4) Feature interpretations were not significantly different between the originals and the copies. (5) Perception of image quality did not affect image interpretation. Continuation and improvement of this research ca be accomplished by: using a case population more sensitive to MTF changes, i.e., asymptomatic women with minimum breast cancer, more observers (including less experienced radiologists and experienced technologists) must collaborate in the study, and using a minimum of 200 benign and 200 malignant cases.

Beyond the Binary: Differences in Eating Disorder Prevalence by Gender Identity in a Transgender Sample.

PubMed

Diemer, Elizabeth W; White Hughto, Jaclyn M; Gordon, Allegra R; Guss, Carly; Austin, S Bryn; Reisner, Sari L

2018-01-01

Purpose: To investigate whether the prevalence of eating disorders (EDs) differs across diverse gender identity groups in a transgender sample. Methods: Secondary analysis of data from Project VOICE, a cross-sectional study of stress and health among 452 transgender adults (ages 18-75 years) residing in Massachusetts. Age-adjusted logistic regression models were fit to compare the prevalence of self-reported lifetime EDs in female-to-male (FTM), male-to-female (MTF), and gender-nonconforming participants assigned male at birth (MBGNC) to gender-nonconforming participants assigned female at birth (FBGNC; referent). Results: The age-adjusted odds of self-reported ED in MTF participants were 0.14 times the odds of self-reported ED in FBGNC participants ( p =0.022). In FTM participants, the age-adjusted odds of self-reported ED were 0.46 times the odds of self-reported ED in FBGNC participants, a marginally significant finding ( p =0.068). No statistically significant differences in ED prevalence were found for MBGNC individuals. Conclusions: Gender nonconforming individuals assigned a female sex at birth appear to have heightened lifetime risk of EDs relative to MTF participants. Further research into specific biologic and psychosocial ED risk factors and gender-responsive intervention strategies are urgently needed. Training clinical providers and ensuring competency of treatment services beyond the gender binary will be vital to addressing this disparity.

Beyond the Binary: Differences in Eating Disorder Prevalence by Gender Identity in a Transgender Sample

PubMed Central

Diemer, Elizabeth W.; White Hughto, Jaclyn M.; Gordon, Allegra R.; Guss, Carly; Austin, S. Bryn; Reisner, Sari L.

2018-01-01

Abstract Purpose: To investigate whether the prevalence of eating disorders (EDs) differs across diverse gender identity groups in a transgender sample. Methods: Secondary analysis of data from Project VOICE, a cross-sectional study of stress and health among 452 transgender adults (ages 18–75 years) residing in Massachusetts. Age-adjusted logistic regression models were fit to compare the prevalence of self-reported lifetime EDs in female-to-male (FTM), male-to-female (MTF), and gender-nonconforming participants assigned male at birth (MBGNC) to gender-nonconforming participants assigned female at birth (FBGNC; referent). Results: The age-adjusted odds of self-reported ED in MTF participants were 0.14 times the odds of self-reported ED in FBGNC participants (p=0.022). In FTM participants, the age-adjusted odds of self-reported ED were 0.46 times the odds of self-reported ED in FBGNC participants, a marginally significant finding (p=0.068). No statistically significant differences in ED prevalence were found for MBGNC individuals. Conclusions: Gender nonconforming individuals assigned a female sex at birth appear to have heightened lifetime risk of EDs relative to MTF participants. Further research into specific biologic and psychosocial ED risk factors and gender-responsive intervention strategies are urgently needed. Training clinical providers and ensuring competency of treatment services beyond the gender binary will be vital to addressing this disparity. PMID:29359198

Plasma Liner Research for MTF at NASA Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Thio, Y. C. F.; Eskridge, R.; Lee, M.; Martin, A.; Smith, J.; Cassibry, J. T.; Wu, S. T.; Kirkpatrick, R. C.; Knapp, C. E.; Turchi, P. J.;

Slanted-edge MTF testing for establishing focus alignment at infinite conjugate of space optical systems with gravity sag effects

NASA Astrophysics Data System (ADS)

Newswander, T.; Riesland, David W.; Miles, Duane; Reinhart, Lennon

2017-09-01

For space optical systems that image extended scenes such as earth-viewing systems, modulation transfer function (MTF) test data is directly applicable to system optical resolution. For many missions, it is the most direct metric for establishing the best focus of the instrument. Additionally, MTF test products can be combined to predict overall imaging performance. For fixed focus instruments, finding the best focus during ground testing is critical to achieving good imaging performance. The ground testing should account for the full-imaging system, operational parameters, and operational environment. Testing the full-imaging system removes uncertainty caused by breaking configurations and the combination of multiple subassembly test results. For earth viewing, the imaging system needs to be tested at infinite conjugate. Operational environment test conditions should include temperature and vacuum. Optical MTF testing in the presence of operational vibration and gravity release is less straightforward and may not be possible on the ground. Gravity effects are mitigated by testing in multiple orientations. Many space telescope systems are designed and built to have optimum performance in a gravity-free environment. These systems can have imaging performance that is dominated by aberration including astigmatism. This paper discusses how the slanted edge MTF test is applied to determine the best focus of a space optical telescope in ground testing accounting for gravity sag effects. Actual optical system test results and conclusions are presented.

Effects of image processing on the detective quantum efficiency

NASA Astrophysics Data System (ADS)

Park, Hye-Suk; Kim, Hee-Joung; Cho, Hyo-Min; Lee, Chang-Lae; Lee, Seung-Wan; Choi, Yu-Na

2010-04-01

Digital radiography has gained popularity in many areas of clinical practice. This transition brings interest in advancing the methodologies for image quality characterization. However, as the methodologies for such characterizations have not been standardized, the results of these studies cannot be directly compared. The primary objective of this study was to standardize methodologies for image quality characterization. The secondary objective was to evaluate affected factors to Modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) according to image processing algorithm. Image performance parameters such as MTF, NPS, and DQE were evaluated using the international electro-technical commission (IEC 62220-1)-defined RQA5 radiographic techniques. Computed radiography (CR) images of hand posterior-anterior (PA) for measuring signal to noise ratio (SNR), slit image for measuring MTF, white image for measuring NPS were obtained and various Multi-Scale Image Contrast Amplification (MUSICA) parameters were applied to each of acquired images. In results, all of modified images were considerably influence on evaluating SNR, MTF, NPS, and DQE. Modified images by the post-processing had higher DQE than the MUSICA=0 image. This suggests that MUSICA values, as a post-processing, have an affect on the image when it is evaluating for image quality. In conclusion, the control parameters of image processing could be accounted for evaluating characterization of image quality in same way. The results of this study could be guided as a baseline to evaluate imaging systems and their imaging characteristics by measuring MTF, NPS, and DQE.

MTF measurement of IR optics in different temperature ranges

NASA Astrophysics Data System (ADS)

Bai, Alexander; Duncker, Hannes; Dumitrescu, Eugen

2017-10-01

Infrared (IR) optical systems are at the core of many military, civilian and manufacturing applications and perform mission critical functions. To reliably fulfill the demanding requirements imposed on today's high performance IR optics, highly accurate, reproducible and fast lens testing is of crucial importance. Testing the optical performance within different temperature ranges becomes key in many military applications. Due to highly complex IR-Applications in the fields of aerospace, military and automotive industries, MTF Measurement under realistic environmental conditions become more and more relevant. A Modulation Transfer Function (MTF) test bench with an integrated thermal chamber allows measuring several sample sizes in a temperature range from -40 °C to +120°C. To reach reliable measurement results under these difficult conditions, a specially developed temperature stable design including an insulating vacuum are used. The main function of this instrument is the measurement of the MTF both on- and off-axis at up to +/-70° field angle, as well as measurement of effective focal length, flange focal length and distortion. The vertical configuration of the system guarantees a small overall footprint. By integrating a high-resolution IR camera with focal plane array (FPA) in the detection unit, time consuming measurement procedures such as scanning slit with liquid nitrogen cooled detectors can be avoided. The specified absolute accuracy of +/- 3% MTF is validated using internationally traceable reference optics. Together with a complete and intuitive software solution, this makes the instrument a turn-key device for today's state-of- the-art optical testing.

Copper Sensing Function of Drosophila Metal-Responsive Transcription Factor-1 Is Mediated By a Tetranuclear Cu(I) Cluster

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

Chen, X.; Hua, H.; Balamurugan, K.

2009-05-12

Drosophila melanogaster MTF-1 (dMTF-1) is a copper-responsive transcriptional activator that mediates resistance to Cu, as well as Zn and Cd. Here, we characterize a novel cysteine-rich domain which is crucial for sensing excess intracellular copper by dMTF-1. Transgenic flies expressing mutant dMTF-1 containing alanine substitutions of two, four or six cysteine residues within the sequence {sup 547}CNCTNCKCDQTKSCHGGDC{sup 565} are significantly or completely impaired in their ability to protect flies from copper toxicity and fail to up-regulate MtnA (metallothionein) expression in response to excess Cu. In contrast, these flies exhibit wild-type survival in response to copper deprivation thus revealing that themore » cysteine cluster domain is required only for sensing Cu load by dMTF-1. Parallel studies show that the isolated cysteine cluster domain is required to protect a copper-sensitive S. cerevisiae ace1 strain from copper toxicity. Cu(I) ligation by a Cys-rich domain peptide fragment drives the cooperative assembly of a polydentate [Cu{sub 4}-S{sub 6}] cage structure, characterized by a core of trigonally S{sub 3} coordinated Cu(I) ions bound by bridging thiolate ligands. While reminiscent of Cu{sub 4}-L{sub 6} (L = ligand) tetranuclear clusters in copper regulatory transcription factors of yeast, the absence of significant sequence homology is consistent with convergent evolution of a sensing strategy particularly well suited for Cu(I).« less

2MTF - VI. Measuring the velocity power spectrum

NASA Astrophysics Data System (ADS)

Howlett, Cullan; Staveley-Smith, Lister; Elahi, Pascal J.; Hong, Tao; Jarrett, Tom H.; Jones, D. Heath; Koribalski, Bärbel S.; Macri, Lucas M.; Masters, Karen L.; Springob, Christopher M.

2017-11-01

We present measurements of the velocity power spectrum and constraints on the growth rate of structure fσ8, at redshift zero, using the peculiar motions of 2062 galaxies in the completed 2MASS Tully-Fisher survey (2MTF). To accomplish this we introduce a model for fitting the velocity power spectrum including the effects of non-linear redshift space distortions (RSD), allowing us to recover unbiased fits down to scales k = 0.2 h Mpc-1 without the need to smooth or grid the data. Our fitting methods are validated using a set of simulated 2MTF surveys. Using these simulations we also identify that the Gaussian distributed estimator for peculiar velocities of Watkins & Feldman is suitable for measuring the velocity power spectrum, but sub-optimal for the 2MTF data compared to using magnitude fluctuations δm, and that, whilst our fits are robust to a change in fiducial cosmology, future peculiar velocity surveys with more constraining power may have to marginalize over this. We obtain scale-dependent constraints on the growth rate of structure in two bins, finding fσ 8 = [0.55^{+0.16}_{-0.13},0.40^{+0.16}_{-0.17}] in the ranges k = [0.007-0.055, 0.55-0.150] h Mpc-1. We also find consistent results using four bins. Assuming scale-independence we find a value fσ 8 = 0.51^{+0.09}_{-0.08}, a ˜16 per cent measurement of the growth rate. Performing a consistency check of general relativity (GR) and combining our results with cosmic microwave background data only we find γ = 0.45^{+0.10}_{-0.11}, a remarkable constraint considering the small number of galaxies. All of our results are completely independent of the effects of galaxy bias, and fully consistent with the predictions of GR (scale-independent fσ8 and γ ≈ 0.55).

Transgender Transitioning and Change of Self-Reported Sexual Orientation

PubMed Central

Höhne, Nina; Stalla, Günter K.; Sievers, Caroline

2014-01-01

Objective Sexual orientation is usually considered to be determined in early life and stable in the course of adulthood. In contrast, some transgender individuals report a change in sexual orientation. A common reason for this phenomenon is not known. Methods We included 115 transsexual persons (70 male-to-female “MtF” and 45 female-to-male “FtM”) patients from our endocrine outpatient clinic, who completed a questionnaire, retrospectively evaluating the history of their gender transition phase. The questionnaire focused on sexual orientation and recalled time points of changes in sexual orientation in the context of transition. Participants were further asked to provide a personal concept for a potential change in sexual orientation. Results In total, 32.9% (n =  23) MtF reported a change in sexual orientation in contrast to 22.2% (n =  10) FtM transsexual persons (p =  0.132). Out of these patients, 39.1% (MtF) and 60% (FtM) reported a change in sexual orientation before having undergone any sex reassignment surgery. FtM that had initially been sexually oriented towards males ( = androphilic), were significantly more likely to report on a change in sexual orientation than gynephilic, analloerotic or bisexual FtM (p  =  0.012). Similarly, gynephilic MtF reported a change in sexual orientation more frequently than androphilic, analloerotic or bisexual MtF transsexual persons (p  =  0.05). Conclusion In line with earlier reports, we reveal that a change in self-reported sexual orientation is frequent and does not solely occur in the context of particular transition events. Transsexual persons that are attracted by individuals of the opposite biological sex are more likely to change sexual orientation. Qualitative reports suggest that the individual's biography, autogynephilic and autoandrophilic sexual arousal, confusion before and after transitioning, social and self-acceptance, as well as concept of sexual orientation itself may explain this phenomenon. PMID:25299675

A cross-platform survey of CT image quality and dose from routine abdomen protocols and a method to systematically standardize image quality.

PubMed

Favazza, Christopher P; Duan, Xinhui; Zhang, Yi; Yu, Lifeng; Leng, Shuai; Kofler, James M; Bruesewitz, Michael R; McCollough, Cynthia H

2015-11-07

Through this investigation we developed a methodology to evaluate and standardize CT image quality from routine abdomen protocols across different manufacturers and models. The influence of manufacturer-specific automated exposure control systems on image quality was directly assessed to standardize performance across a range of patient sizes. We evaluated 16 CT scanners across our health system, including Siemens, GE, and Toshiba models. Using each practice's routine abdomen protocol, we measured spatial resolution, image noise, and scanner radiation output (CTDIvol). Axial and in-plane spatial resolutions were assessed through slice sensitivity profile (SSP) and modulation transfer function (MTF) measurements, respectively. Image noise and CTDIvol values were obtained for three different phantom sizes. SSP measurements demonstrated a bimodal distribution in slice widths: an average of 6.2  ±  0.2 mm using GE's 'Plus' mode reconstruction setting and 5.0  ±  0.1 mm for all other scanners. MTF curves were similar for all scanners. Average spatial frequencies at 50%, 10%, and 2% MTF values were 3.24  ±  0.37, 6.20  ±  0.34, and 7.84  ±  0.70 lp cm(-1), respectively. For all phantom sizes, image noise and CTDIvol varied considerably: 6.5-13.3 HU (noise) and 4.8-13.3 mGy (CTDIvol) for the smallest phantom; 9.1-18.4 HU and 9.3-28.8 mGy for the medium phantom; and 7.8-23.4 HU and 16.0-48.1 mGy for the largest phantom. Using these measurements and benchmark SSP, MTF, and image noise targets, CT image quality can be standardized across a range of patient sizes.

Cal/Val activities for DubaiSat-2 performance assessment

NASA Astrophysics Data System (ADS)

Bushahab, A.; Al-Mansoori, S.; Al-Suwaidi, K.; Al Matroushi, Hessa; Al-Tunaiji, E.; Al Shamsi, Meera

2014-10-01

Emirates Institution for Advanced Science and Technology (EIAST) was established by the Dubai Government in 2006. After three years of working together with Satrec Initiative (South Korea), EIAST was able to launch DubaiSat-1 on the 29th of July 2009. Building on the success of DubaiSat-1 and the roll out of the knowledge transfer program, UAE engineers were involved in almost 70% of the total build and design of DubaiSat-2. Targeting the commercial market, DubaiSat-2 was launched on the 21st of November 2013 for capturing 1-meter resolution images. The 1st Cal/Val phase was the most critical phase in the satellite life-time, where most of the initial measurements took place. This phase extended over the period of 25/11/2013 till 12/12/2013. Moreover, this phase included most of the relative calibration tasks, color balancing and band matching. 2nd Cal/Val phase included most of the debugging and the pointing accuracy calibration tests. This phase extended over the period of 11/02/2014 till 09/03/2014. This phase emphasized on the calibration of the pointing accuracy. The 3rd Cal/Val phase included fine tuning for the Gyro system to further increase the stability of the satellite and thus improve the pointing accuracy. Moreover, new techniques were implemented to the Pan-Sharpening and to the MTF compensation procedures to enhance the final product. This phase extended over the period of 04/05/2014 till 21/05/2014.

A randomized, single-blind trial of 5% minoxidil foam once daily versus 2% minoxidil solution twice daily in the treatment of androgenetic alopecia in women.

PubMed

Blume-Peytavi, Ulrike; Hillmann, Kathrin; Dietz, Ekkehart; Canfield, Douglas; Garcia Bartels, Natalie

2011-12-01

Although twice-daily application of propylene glycol-containing 2% minoxidil topical solution (MTS) stimulates new hair growth, higher concentrations of minoxidil in a once-daily, propylene glycol-free formulation may improve efficacy and reduce unpleasant side effects. We sought to compare the efficacy, safety, and acceptability and to show noninferiority of once-daily 5% minoxidil topical foam (MTF) with twice-daily 2% MTS in women with androgenetic alopecia. A total of 113 women with androgenetic alopecia were randomized to 24 weeks of treatment with 5% MTF or 2% MTS. The primary efficacy parameter was change from baseline in nonvellus target area hair count at week 24. Secondary end points included change in nonvellus target area hair width, overall efficacy by global photographic review as assessed by treatment-blinded evaluators and the subject herself, adverse events, and participants' assessment of product aesthetics. After 24 weeks, women randomized to 5% MTF once daily showed noninferior target area hair count and target area hair width and experienced greater, but nonsignificant, improvements in target area hair count, target area hair width, and overall efficacy by global photographic review than those randomized to 2% MTS used twice daily. 5% MTF was significantly superior to 2% MTS in participants' agreement with "the treatment does not interfere with styling my hair" (P = .002). Women randomized to 5% MTF experienced significantly lower rates of local intolerance (P = .046) especially in pruritus and dandruff compared with 2% MTS. Because of differences in the formulations tested, study participants were not blinded to treatment. Once-daily 5% MTF is noninferior and as effective for stimulating hair growth as twice-daily 2% MTS in women with androgenetic alopecia and is associated with several aesthetic and practical advantages. Copyright © 2010 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

Trends in teen driver licensure, driving patterns and crash involvement in the United States, 2006-2015.

PubMed

Shults, Ruth A; Williams, Allan F

2017-09-01

The Monitoring the Future (MTF) survey provides nationally-representative annual estimates of licensure and driving patterns among U.S. teens. A previous study using MTF data reported substantial declines in the proportion of high school seniors that were licensed to drive and increases in the proportion of nondrivers following the recent U.S. economic recession. To explore whether licensure and driving patterns among U.S. high school seniors have rebounded in the post-recession years, we analyzed MTF licensure and driving data for the decade of 2006-2015. We also examined trends in teen driver involvement in fatal and nonfatal injury crashes for that decade using data from the Fatality Analysis Reporting System and National Automotive Sampling System General Estimates System, respectively. During 2006-2015, the proportion of high school seniors that reported having a driver's license declined by 9 percentage points (11%) from 81% to 72% and the proportion that did not drive during an average week increased by 8 percentage points (44%) from 18% to 26%. The annual proportion of black seniors that did not drive was consistently greater than twice the proportion of nondriving white seniors. Overall during the decade, 17- and 18-year-old drivers experienced large declines in fatal and nonfatal injury crashes, although crashes increased in both 2014 and 2015. The MTF data indicate that licensure and driving patterns among U.S. high school seniors have not rebounded since the economic recession. The recession had marked negative effects on teen employment opportunities, which likely influenced teen driving patterns. Possible explanations for the apparent discrepancies between the MTF data and the 2014 and 2015 increases in crashes are explored. MTF will continue to be an important resource for clarifying teen driving trends in relation to crash trends and informing strategies to improve teen driver safety. Published by Elsevier Ltd.

A Phase III, Multicenter, Parallel-Design Clinical Trial to Compare the Efficacy and Safety of 5% Minoxidil Foam Versus Vehicle in Women With Female Pattern Hair Loss.

PubMed

Bergfeld, Wilma; Washenik, Ken; Callender, Valerie; Zhang, Paul; Quiza, Carlos; Doshi, Uday; Blume-Peytavi, Ulrike

2016-07-01

BACKGROUND Female pattern hair loss (FPHL) is a common hair disorder that affects millions of women. A new 5% minoxidil topical foam (MTF) formulation, which does not contain propylene glycol, has been developed.
To compare the efficacy and safety of once-daily 5% MTF with vehicle foam for the treatment of FPHL.
This was a Phase III, randomized, double-blind, vehicle-controlled, parallel-group, international multicenter trial (17 sites) in women aged at least 18 years with FPHL (grade D3 to D6 on the Savin Density Scale), treated once daily with 5% MTF or vehicle foam for 24 weeks. The co-primary efficacy endpoints were the change from baseline at week 24 in target area hair count (TAHC) and subject assessment of scalp coverage. Also evaluated were TAHC at week 12, expert panel review of hair regrowth at week 24, and change from baseline in total unit area density (TUAD, sum of hair diameters/cm²) at weeks 12 and 24.
A total of 404 women were enrolled. At 12 and 24 weeks, 5% MTF treatment resulted in regrowth of 10.9 hairs/cm² and 9.1 hairs/cm² more than vehicle foam, respectively (both P<.0001). Improved scalp coverage at week 24 was observed by both subject self-assessment (0.69-point improvement over vehicle foam; P<.0001) and expert panel review (0.36-point improvement over the vehicle foam; P<.0001). TUAD increased by 658 μm/cm² and 644 μm/cm² more with 5% MTF than with vehicle foam at weeks 12 and 24, respectively (both P<.0001). MTF was well tolerated. A low incidence of scalp irritation and facial hypertrichosis was observed, with no clinically significant differences between groups.
Five percent MTF once daily for 24 weeks was well tolerated and promoted hair regrowth in women with FPHL, resulting in improved scalp coverage and increased hair density compared with vehicle foam. ClinicalTrials.gov identifier: nCT01226459

J Drugs Dermatol. 2016;15(7):874-881.

Application of Oversampling to obtain the MTF of Digital Radiology Equipment.

NASA Astrophysics Data System (ADS)

Narváez, M.; Graffigna, J. P.; Gómez, M. E.; Romo, R.

2016-04-01

Within the objectives of theproject Medical Image Processing for QualityAssessment ofX Ray Imaging, the present research work is aimed at developinga phantomX ray image and itsassociated processing algorithms in order to evaluatethe image quality rendered by digital X ray equipment. These tools are used to measure various image parameters, among which spatial resolution shows afundamental property that can be characterized by the Modulation Transfer Function (MTF)of an imaging system [1]. After performing a thorough literature surveyon imaging quality control in digital X film in Argentine and international publications, it was decided to adopt for this work the Norm IEC 62220 1:2003 that recommends using an image edge as a testingmethod. In order to obtain the characterizing MTF, a protocol was designedfor unifying the conditions under which the images are acquired for later evaluation. The protocol implied acquiring a radiography image by means of a specific referential technique, i.e. referred either to voltage, current, time, distance focus plate (/film?) distance, or other referential parameter, and to interpret the image through a system of computed radiology or direct digital radiology. The contribution of the work stems from the fact that, even though the traditional way of evaluating an X film image quality has relied mostly on subjective methods, this work presents an objective evaluative toolfor the images obtained with a givenequipment, followed by a contrastive analysis with the renderings from other X filmimaging sets.Once the images were obtained, specific calculations were carried out. Though there exist some methods based on the subjective evaluation of the quality of image, this work offers an objective evaluation of the equipment under study. Finally, we present the results obtained on different equipment.

MTF Database: A Repository of Students' Academic Performance Measurements for the Development of Techniques for Evaluating Team Functioning

ERIC Educational Resources Information Center

Hsiung, Chin-Min; Zheng, Xiang-Xiang

2015-01-01

The Measurements for Team Functioning (MTF) database contains a series of student academic performance measurements obtained at a national university in Taiwan. The measurements are acquired from unit tests and homework tests performed during a core mechanical engineering course, and provide an objective means of assessing the functioning of…

Dynamic MTF, an innovative test bench for detector characterization

NASA Astrophysics Data System (ADS)

Emmanuel, Rossi; Raphaël, Lardière; Delmonte, Stephane

2017-11-01

PLEIADES HR are High Resolution satellites for Earth observation. Placed at 695km they reach a 0.7m spatial resolution. To allow such performances, the detectors are working in a TDI mode (Time and Delay Integration) which consists in a continuous charge transfer from one line to the consecutive one while the image is passing on the detector. The spatial resolution, one of the most important parameter to test, is characterized by the MTF (Modulation Transfer Function). Usually, detectors are tested in a staring mode. For a higher level of performances assessment, a dedicated bench has been set-up, allowing detectors' MTF characterization in the TDI mode. Accuracy and reproducibility are impressive, opening the door to new perspectives in term of HR imaging systems testing.

Breadboard linear array scan imager using LSI solid-state technology

NASA Technical Reports Server (NTRS)

Tracy, R. A.; Brennan, J. A.; Frankel, D. G.; Noll, R. E.

1976-01-01

The performance of large scale integration photodiode arrays in a linear array scan (pushbroom) breadboard was evaluated for application to multispectral remote sensing of the earth's resources. The technical approach, implementation, and test results of the program are described. Several self scanned linear array visible photodetector focal plane arrays were fabricated and evaluated in an optical bench configuration. A 1728-detector array operating in four bands (0.5 - 1.1 micrometer) was evaluated for noise, spectral response, dynamic range, crosstalk, MTF, noise equivalent irradiance, linearity, and image quality. Other results include image artifact data, temporal characteristics, radiometric accuracy, calibration experience, chip alignment, and array fabrication experience. Special studies and experimentation were included in long array fabrication and real-time image processing for low-cost ground stations, including the use of computer image processing. High quality images were produced and all objectives of the program were attained.

Efficacy and Safety of Once-Daily Minoxidil Foam 5% Versus Twice-Daily Minoxidil Solution 2% in Female Pattern Hair Loss: A Phase III, Randomized, Investigator-Blinded Study.

PubMed

Blume-Peytavi, Ulrike; Shapiro, Jerry; Messenger, Andrew G; Hordinsky, Maria K; Zhang, Paul; Quiza, Carlos; Doshi, Uday; Olsen, Elise A

2016-07-01

A once-daily minoxidil topical foam (MTF) has been developed to treat female pattern hair loss.
Determine noninferiority of once-daily 5% MTF versus twice-daily 2% minoxidil topical solution (MTS) based on the change from baseline in target area hair count (TAHC) at 24 weeks. In a randomized, phase III trial, women with female pattern hair loss received once-daily 5% MTF (n=161) or twice-daily 2% MTS (n=161) for 52 weeks. Primary endpoint was change from baseline in TAHC at 24 weeks. Secondary endpoint was change from baseline in TAHC at 12 weeks. Exploratory endpoints included change in total unit area density and change in overall scalp coverage.
Once-daily 5% MTF increased TAHC from baseline (adjusted mean ± standard error) by 23.9 ± 2.1 hairs/cm² at week 24. Twice-daily 2% MTS increased TAHC 24.2 ± 2.1 hairs/cm² at week 24. The treatment difference was -0.3 hairs/cm² (95% CI = -6.0, 5.4). Since the lower bound of the 95% CI was less than -5.0, the prespecified noninferiority goal was not met. Both treatments were well tolerated.
Once-daily 5% MTF and twice-daily 2% MTS induced hair regrowth in female pattern hair loss, but prespecified noninferiority criteria were not met.
ClinicalTrials.gov identifier: NCT01145625

J Drugs Dermatol. 2016;15(7):883-889.

Assessment of Motivational Cognitions in Diabetes Self-Care: the Motivation Thought Frequency Scales for Glucose Testing, Physical Activity and Healthy Eating.

PubMed

Parham, Sophie C; Kavanagh, David J; Gericke, Christian A; King, Neil; May, Jon; Andrade, Jackie

2017-06-01

There is a need for improved measurement of motivation for diabetes self-care. The Elaborated Intrusion Theory of Desire offers a coherent framework for understanding and identifying the cognitive-affective events that constitute the subjective experience of motivation and may therefore inform the development of such an instrument. Recent research has shown the resultant Motivation Thought Frequency scale (MTF) to have a stable factor structure (Intensity, Incentives Imagery, Self-Efficacy Imagery, Availability) when applied to physical activity, excessive snacking or alcohol use in the general population. The current study aimed to confirm the four-factor structure of the MTF for glucose testing, physical activity and healthy eating in people with type 2 diabetes. Associations with self-reports of concurrent diabetic self-care behaviours were also examined. Confirmatory factor analyses tested the internal structure, and multiple regressions assessed the scale's relationship with concurrent self-care behaviours. The MTF was completed by 340 adults with type 2 diabetes, and 237 from that sample also reported self-care behaviours. Separate MTFs assessed motivation for glucose testing, physical activity and healthy eating. Self-care was assessed using questions from the Summary of Diabetes Self-Care Activities. The MTF for each goal achieved an acceptable fit on all indices after selected errors within factors were allowed to intercorrelate. Intensity and Self-Efficacy Imagery provided the strongest and most consistent correlations with relevant self-care behaviours. Results provide preliminary support for the MTF in a diabetes sample. Testing of its sensitivity to change and its predictive utility over time is needed.

The modulation transfer function and signal-to-noise ratio of different digital filters: a technical approach.

PubMed

Brüllmann, D D; d'Hoedt, B

2011-05-01

The aim of this study was to illustrate the influence of digital filters on the signal-to-noise ratio (SNR) and modulation transfer function (MTF) of digital images. The article will address image pre-processing that may be beneficial for the production of clinically useful digital radiographs with lower radiation dose. Three filters, an arithmetic mean filter, a median filter and a Gaussian filter (standard deviation (SD) = 0.4), with kernel sizes of 3 × 3 pixels and 5 × 5 pixels were tested. Synthetic images with exactly increasing amounts of Gaussian noise were created to gather linear regression of SNR before and after application of digital filters. Artificial stripe patterns with defined amounts of line pairs per millimetre were used to calculate MTF before and after the application of the digital filters. The Gaussian filter with a 5 × 5 kernel size caused the highest noise suppression (SNR increased from 2.22, measured in the synthetic image, to 11.31 in the filtered image). The smallest noise reduction was found with the 3 × 3 median filter. The application of the median filters resulted in no changes in MTF at the different resolutions but did result in the deletion of smaller structures. The 5 × 5 Gaussian filter and the 5 × 5 arithmetic mean filter showed the strongest changes of MTF. The application of digital filters can improve the SNR of a digital sensor; however, MTF can be adversely affected. As such, imaging systems should not be judged solely on their quoted spatial resolutions because pre-processing may influence image quality.

Monitoring the Future National Survey Results on Drug Use, 1975-2016. Volume I, Secondary School Students

ERIC Educational Resources Information Center

Miech, Richard A.; Johnston, Lloyd D.; O'Malley, Patrick M.; Bachman, Jerald G.; Schulenberg, John E.; Patrick, Megan E.

2017-01-01

Monitoring the Future (MTF) is designed to give sustained attention to substance use among the nation's youth and adults. It is an investigator-initiated study that originated with and is conducted by a team of research professors at the University of Michigan's Institute for Social Research. Since its onset in 1975, MTF has been continuously…

Monitoring the Future National Survey Results on Drug Use, 1975-2015. Volume I, Secondary School Students

ERIC Educational Resources Information Center

Miech, Richard A.; Johnston, Lloyd D.; O'Malley, Patrick M.; Bachman, Jerald G.; Schulenberg, John E.

2016-01-01

Monitoring the Future (MTF) is designed to give sustained attention to substance use among the nation's youth and adults. It is an investigator-initiated study that originated with and is conducted by a team of research professors at the University of Michigan's Institute for Social Research. Since its onset in 1975, MTF has been continuously…

Examining the Spatial Frequency Components of a Digital Dental Detector

NASA Astrophysics Data System (ADS)

Anastasiou, A.; Michail, C.; Koukou, V.; Martini, N.; Bakas, A.; Papastamati, F.; Maragkaki, P.; Lavdas, L.; Fountos, G.; Valais, I.; Kalyvas, N.

2017-11-01

Digital X-ray detectors are widely used in dental radiography. The scope of this work is the examination of the spatial frequency component of a dedicated dental CMOS detector. A commercially available SCHICK CDR CMOS detector was irradiated at a Del Medical Eureka X-ray system at 60kVp and 70kVp. The irradiation setup included images of an edge, for Modulation Transfer Function (MTF) calculation. The air-KERMA was measured with an RTI PIRANHA X-ray multimeter. The images were evaluated in ‘for presentation’ format with the use of ImageJ software. The linear range of the detector was found in the range 13μGy-183μGy at 60 kVp and 18μGy-180μGy at 70 kVp. By inspecting the MTF curves it was found that MTF(6lp/mm)60kVp=0.29 and MTF(6lp/mm)70kVp=0.25. The inspection of the Normalized Noise Power Spetrum (NNPS) showed similar low noise components. Our results indicate that this detector presents comparable performance at both kVp, although its X-ray response (pixel value vs air KERMA) was not equal to previously published results, for the same detector type.

Insulin resistance in clomiphene responders and non-responders with polycystic ovarian disease and therapeutic effects of metformin.

PubMed

Parsanezhad, M E; Alborzi, S; Zarei, A; Dehbashi, S; Omrani, G

2001-10-01

To evaluate the clinical features, endocrine and metabolic profiles in clomiphene (CC) responders and non-responders with polycystic ovarian disease (PCOD), and to examine the effects of metformin (MTF) on the above parameters of CC resistance. A prospective clinical trial was undertaken at the infertility division of a university teaching hospital. Forty-one CC responders were selected and their hormonal and clinical features were determined. Forty-one CC-resistant PCOD women were also selected and clinical features; metabolic and hormonal profiles before and after treatment with MTF 1500 mg/day for 6-8 weeks were evaluated. Women who failed to conceive were treated by CC while continuing to take MTF. CC responders had higher insulin levels while non-responders were hyperinsulinemic. Menstrual irregularities improved in 30%. Mean+/-S.D. area under curve of insulin decreased from 297.58+/-191.33 to 206+/-0.1 mIU/ml per min (P=0.005). Only 39.39% ovulated and 24.24% conceived. PCOD is associated with insulin resistance (IR) particularly in CC-resistant women. Insulin resistance and androgen levels are significantly higher in obese patients. MTF therapy improved hyperandrogenemia, IR, and pregnancy rate.

Microalgal biomass production and on-site bioremediation of carbon dioxide, nitrogen oxide and sulfur dioxide from flue gas using Chlorella sp. cultures.

PubMed

Chiu, Sheng-Yi; Kao, Chien-Ya; Huang, Tzu-Ting; Lin, Chia-Jung; Ong, Seow-Chin; Chen, Chun-Da; Chang, Jo-Shu; Lin, Chih-Sheng

2011-10-01

The growth and on-site bioremediation potential of an isolated thermal- and CO₂-tolerant mutant strain, Chlorella sp. MTF-7, were investigated. The Chlorella sp. MTF-7 cultures were directly aerated with the flue gas generated from coke oven of a steel plant. The biomass concentration, growth rate and lipid content of Chlorella sp. MTF-7 cultured in an outdoor 50-L photobioreactor for 6 days was 2.87 g L⁻¹ (with an initial culture biomass concentration of 0.75 g L⁻¹), 0.52 g L⁻¹ d⁻¹ and 25.2%, respectively. By the operation with intermittent flue gas aeration in a double-set photobioreactor system, average efficiency of CO₂ removal from the flue gas could reach to 60%, and NO and SO₂ removal efficiency was maintained at approximately 70% and 50%, respectively. Our results demonstrate that flue gas from coke oven could be directly introduced into Chlorella sp. MTF-7 cultures to potentially produce algal biomass and efficiently capture CO₂, NO and SO₂ from flue gas. Copyright © 2011 Elsevier Ltd. All rights reserved.

Regional gray matter variation in male-to-female transsexualism

PubMed Central

Luders, Eileen; Sánchez, Francisco J.; Gaser, Christian; Toga, Arthur W.; Narr, Katherine L.; Hamilton, Liberty S.; Vilain, Eric

2009-01-01

Gender identity—one's sense of being a man or a woman—is a fundamental perception experienced by all individuals that extends beyond biological sex. Yet, what contributes to our sense of gender remains uncertain. Since individuals who identify as transsexual report strong feelings of being the opposite sex and a belief that their sexual characteristics do not reflect their true gender, they constitute an invaluable model to understand the biological underpinnings of gender identity. We analyzed MRI data of 24 male-to-female (MTF) transsexuals not yet treated with cross-sex hormones in order to determine whether gray matter volumes in MTF transsexuals more closely resemble people who share their biological sex (30 control men), or people who share their gender identity (30 control women). Results revealed that regional gray matter variation in MTF transsexuals is more similar to the pattern found in men than in women. However, MTF transsexuals show a significantly larger volume of regional gray matter in the right putamen compared to men. These findings provide new evidence that transsexualism is associated with distinct cerebral pattern, which supports the assumption that brain anatomy plays a role in gender identity. PMID:19341803

Regional gray matter variation in male-to-female transsexualism.

PubMed

Luders, Eileen; Sánchez, Francisco J; Gaser, Christian; Toga, Arthur W; Narr, Katherine L; Hamilton, Liberty S; Vilain, Eric

2009-07-15

Gender identity-one's sense of being a man or a woman-is a fundamental perception experienced by all individuals that extends beyond biological sex. Yet, what contributes to our sense of gender remains uncertain. Since individuals who identify as transsexual report strong feelings of being the opposite sex and a belief that their sexual characteristics do not reflect their true gender, they constitute an invaluable model to understand the biological underpinnings of gender identity. We analyzed MRI data of 24 male-to-female (MTF) transsexuals not yet treated with cross-sex hormones in order to determine whether gray matter volumes in MTF transsexuals more closely resemble people who share their biological sex (30 control men), or people who share their gender identity (30 control women). Results revealed that regional gray matter variation in MTF transsexuals is more similar to the pattern found in men than in women. However, MTF transsexuals show a significantly larger volume of regional gray matter in the right putamen compared to men. These findings provide new evidence that transsexualism is associated with distinct cerebral pattern, which supports the assumption that brain anatomy plays a role in gender identity.

Model MTF for the mosaic window

NASA Astrophysics Data System (ADS)

Xing, Zhenchong; Hong, Yongfeng; Zhang, Bao

2017-10-01

An electro-optical targeting system mounted either within an airframe or housed in separate pods requires a window to form an environmental barrier to the outside world. In current practice, such windows usually use a mosaic or segmented window. When scanning the target, internally gimbaled systems sweep over the window, which can affect the modulation transfer function (MTF) due to wave-front division and optical path differences arising from the thickness/wedge differences between panes. In this paper, a mathematical model of the MTF of the mosaic window is presented that allows an analysis of influencing factors; we show how the model may be integrated into ZEMAX® software for optical design. The model can be used to guide both the design and the tolerance analysis of optical systems that employ a mosaic window.

Modulation transfer function of partial gating detector by liquid crystal auto-controlling light intensity

NASA Astrophysics Data System (ADS)

Yang, Xusan; Tang, Yuanhe; Liu, Kai; Liu, Hanchen; Gao, Haiyang; Li, Qing; Zhang, Ruixia; Ye, Na; Liang, Yuan; Zhao, Gaoxiang

2008-12-01

Based on the electro-optical properties of liquid crystal, we have designed a novel partial gating detector. Liquid crystal can be taken to change its own transmission according to the light intensity outside. Every single pixel of the image is real-time modulated by liquid crystal, thus the strong light is weakened and low light goes through the detector normally .The purpose of partial-gating strong light (>105lx) can be achieved by this detector. The modulation transfer function (MTF) equations of the main optical sub-systems are calculated in this paper, they are liquid crystal panels, linear fiber panel and CCD array detector. According to the relevant size, the MTF value of this system is fitted out. The result is MTF= 0.518 at Nyquist frequency.

Cascaded systems analysis of photon counting detectors

PubMed Central

Xu, J.; Zbijewski, W.; Gang, G.; Stayman, J. W.; Taguchi, K.; Lundqvist, M.; Fredenberg, E.; Carrino, J. A.; Siewerdsen, J. H.

2014-01-01

Purpose: Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). Methods: A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1–7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. Results: The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f50 (spatial-frequency at which the MTF falls to a value of 0.50) by ∼30% with corresponding improvement in DQE. The range in exposure and additive noise for which PCDs yield intrinsically higher DQE was quantified, showing performance advantages under conditions of very low-dose, high additive noise, and high fidelity rejection of coincident photons. Conclusions: The model for PCD signal and noise performance agreed with measurements of detector signal, MTF, and NPS and provided a useful basis for understanding complex dependencies in PCD imaging performance and the potential advantages (and disadvantages) in comparison to EIDs as well as an important guide to task-based optimization in developing new PCD imaging systems. PMID:25281959

Phase and group delay of S-band megawatt Cassegrain diplexer and S-band megawatt transmit filter

NASA Technical Reports Server (NTRS)

Lay, R.

1977-01-01

The phase characteristics and group delay of the S-band Megawatt Cassegrain Diplexer (MCD) and S-band Megawatt Transmit Filter (MTF) are reported. These phase measurements on the MCD and MTF were done in response to the need to obtain the total DSS hardware ground delay required for very long baseline interferometry and ranging radio metric measurements.

PRIMUS/NAVCARE Cost-Effectiveness Analysis

DTIC Science & Technology

1991-04-08

ICD-9-CM diagnosis codes that occurred most frequently in the medical record sample - 328.9 ( otitis media , unspecified) and 465.9 (upper...when attention is focused upon a single diagnosis, the MTF CECs are no longer consistently above the PRIMUS CECs. For otitis media , the MTF CECs are...CHAMPUS-EQUIVALENT COSTS FOR SELECTED DIAGNOSES 328.9 OTITIS MEDIA , UNSPECIFIED Sample Size Mean 95% Confidence Interval Upper Limit Lower

Prevalence of Human Immunodeficiency Virus, Hepatitis B Virus, and Hepatitis C Virus Infections Among Transgender Persons Referred to an Italian Center for Total Sex Reassignment Surgery.

PubMed

Luzzati, Roberto; Zatta, Marta; Pavan, Nicola; Serafin, Maurizia; Maurel, Cristina; Trombetta, Carlo; Barbone, Fabio

2016-07-01

The burden of human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) infections in transgender population is an underestimated issue. We performed a study to evaluate the prevalence of such infections in transgender persons addressed our center for total sex reassignment surgery (SRS). All transgender persons undergoing SRS from 2000 to 2014 were evaluated retrospectively. Participant characteristics and results of HIV, HBV, and HCV testing were collected. Exact Fisher test, Cochran-Armitage tests for trend and correct prevalence ratios were estimated. Among 498 transgender persons, 243 had confirmed serological data. Of them, 25 were female-to-male and 218 male-to-female (MtF) subjects. The prevalence of HIV, HBV and HCV infections was 0%, 4.0%, and 8.0% in female-to-male, and 12.1%, 4.6%, and 3.7% in MtF. Among MtF, younger age and earlier year of SRS were associated with lower HIV prevalence. From the multivariate model, the mutually adjustment prevalence ratios were 1.9 (95% confidence interval [95% CI], 1.2-3.1) for SRS in 2005-2010 and 3.6 (95% CI, 1.3-9.4) in 2010-2014, as compared with SRS in 2000-2004; and 4.7 (95% CI, 2.4-9.4) for South Americans as compared with others. Among the HCV-positive MtF, 57.1% were also HIV-positive. Regarding HBV, the immunity was 38.5% and, after mutual adjustment, the prevalence ratios were 2.1 (95% CI, 1.3-3.4) for South Americans versus others and 2.2 (95% CI, 1.6-3.1) for year of birth ≥ 1980. The prevalence of HBV and HCV infections among our transgender persons overlaps that reported in the general population, but HCV prevalence was much higher in HIV-infected MtF. The high burden of HIV infection among MtF and its recent incremented prevalence points out that social and medical support should be strongly promoted in such population.

Light-reflection random-target method for measurement of the modulation transfer function of a digital video-camera

NASA Astrophysics Data System (ADS)

Pospisil, J.; Jakubik, P.; Machala, L.

2005-11-01

This article reports the suggestion, realization and verification of the newly developed measuring means of the noiseless and locally shift-invariant modulation transfer function (MTF) of a digital video camera in a usual incoherent visible region of optical intensity, especially of its combined imaging, detection, sampling and digitizing steps which are influenced by the additive and spatially discrete photodetector, aliasing and quantization noises. Such means relates to the still camera automatic working regime and static two-dimensional spatially continuous light-reflection random target of white-noise property. The introduced theoretical reason for such a random-target method is also performed under exploitation of the proposed simulation model of the linear optical intensity response and possibility to express the resultant MTF by a normalized and smoothed rate of the ascertainable output and input power spectral densities. The random-target and resultant image-data were obtained and processed by means of a processing and evaluational PC with computation programs developed on the basis of MATLAB 6.5E The present examples of results and other obtained results of the performed measurements demonstrate the sufficient repeatability and acceptability of the described method for comparative evaluations of the performance of digital video cameras under various conditions.

Dimensional profiles of male to female gender identity disorder: an exploratory research.

PubMed

Fisher, Alessandra D; Bandini, Elisa; Ricca, Valdo; Ferruccio, Naika; Corona, Giovanni; Meriggiola, Maria C; Jannini, Emmanuele A; Manieri, Chiara; Ristori, Jiska; Forti, Gianni; Mannucci, Edoardo; Maggi, Mario

2010-07-01

Male-to-Female Gender Identity Disorder (MtF GID) is a complex phenomenon that could be better evaluated by using a dimensional approach. To explore the aggregation of clinical manifestations of MtF GID in order to identify meaningful variables describing the heterogeneity of the disorder. A consecutive series of 80 MtF GID subjects (mean age 37 +/- 10.3 years), referred to the Interdepartmental Center for Assistance Gender Identity Disorder of Florence and to other Italian centers from July 2008 to June 2009, was studied. Diagnosis was based on formal psychiatric classification criteria. Factor analysis was performed. Several socio-demographic and clinical parameters were investigated. Patients were asked to complete the Bem Sex Role Inventory (BSRI, a self-rating scale to evaluate gender role) and Symptom Checklist-90 Revised (SCL-90-R, a self-rating scale to measure psychological state). Factor analysis identified two dimensional factors: Factor 1 was associated with sexual orientation, and Factor 2 related to behavioral and psychological correlates of early GID development. No correlation was observed between the two factors. A positive correlation between Factor 2 and feminine BSRI score was found, along with a negative correlation between Factor 2 and undifferentiated BSRI score. Moreover, a significant association between SCL-90-R Phobic subscale score and Factor 2 was observed. A variety of other socio-demographic parameters and clinical features were associated with both factors. Behavioral and psychological correlates of Factor 1 (sexual orientation) and Factor 2 (gender identity) do not constitute the framework of two separate clinical entities, but instead represent two dimensions of the complex MtF GID structure, which can be variably intertwined in the same subject. By using factor analysis, we offer a new approach capable of delineating a psychopathological and clinical profile of MtF GID patients.

Twenty years of endocrinologic treatment in transsexualism: analyzing the role of chromosomal analysis and hormonal profiling in the diagnostic work-up.

PubMed

Auer, Matthias K; Fuss, Johannes; Stalla, Guenter K; Athanasoulia, Anastasia P

2013-10-01

To demonstrate that adequate pubertal history, physical examination, and a basal hormone profile is sufficient to exclude disorders of sexual development (DSD) in adult transsexuals and that chromosomal analysis could be omitted in cases of unremarkable hormonal profile and pubertal history. Retrospective chart analysis. Endocrine outpatient clinic of a psychiatric research institute. A total of 475 subjects (302 male-to-female transsexuals [MtF], 173 female-to-male transsexuals [FtM]). Data from 323 (192 MtF/131 FtM) were collected for hormonal and pubertal abnormalities. Information regarding chromosomal analysis was available for 270 patients (165 MtF/105 FtM). None. Pubertal abnormalities, menstrual cycle, and hormonal irregularities in relation to chromosomal analysis conducted by karyotype or hair root analysis. In the MtF group, 5.2% of the patients reported pubertal irregularities and 5.7% hormonal abnormalities, and in the FtM group 3.8% and 19.1%, respectively. Overall chromosomal abnormality in both groups was 1.5% (2.9% in the FtM and 0.6% in the MtF group). The aneuploidies found included one gonosomal aneuploidy (45,X[10]/47,XXX[6]/46,XX[98]), two Robertsonian translocations (45,XXder(14;22)(q10;q10)), and one Klinefelter syndrome (47,XXY) that had already been diagnosed in puberty. Our data show a low incidence of chromosomal abnormalities and thus question routine chromosomal analysis at the baseline evaluation of transsexualism, and suggest that it be considered only in cases of abnormal history or hormonal examination. Copyright © 2013 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Central obscuration effects on optical synthetic aperture imaging

NASA Astrophysics Data System (ADS)

Wang, Xue-wen; Luo, Xiao; Zheng, Li-gong; Zhang, Xue-jun

2014-02-01

Due to the central obscuration problem exists in most optical synthetic aperture systems, it is necessary to analyze its effects on their image performance. Based on the incoherent diffraction limited imaging theory, a Golay-3 type synthetic aperture system was used to study the central obscuration effects on the point spread function (PSF) and the modulation transfer function (MTF). It was found that the central obscuration does not affect the width of the central peak of the PSF and the cutoff spatial frequency of the MTF, but attenuate the first sidelobe of the PSF and the midfrequency of the MTF. The imaging simulation of a Golay-3 type synthetic aperture system with central obscuration proved this conclusion. At last, a Wiener Filter restoration algorithm was used to restore the image of this system, the images were obviously better.

HIV infection risk factors among male-to-female transgender persons: a review of the literature.

PubMed

De Santis, Joseph P

2009-01-01

Male-to-female (MTF) transgender women experience a host of psychosocial issues such as discrimination, stigmatization, and marginalization. These challenges often limit economic opportunities, affect mental health, and may place members of this population at an increased risk for HIV infection. This report presents a review of the literature that focuses on risk factors for HIV infection specific to the MTF population. Factors including needle sharing and substance abuse, high-risk sexual behaviors, commercial sex work, health care access, lack of knowledge regarding HIV transmission, violence, stigma and discrimination, and mental health issues have been identified in the literature as risk factors for the acquisition of HIV infection by members of this population. Implications for care provided to MTF transgender persons are presented, and suggestions for future research are identified.

Adsorbed radioactivity and radiographic imaging of surfaces of stainless steel and titanium

NASA Astrophysics Data System (ADS)

Jung, Haijo

1997-11-01

Type 304 stainless steel used for typical surface materials of spent fuel shipping casks and titanium were exposed in the spent fuel storage pool of a typical PWR power plant. Adsorption characteristics, effectiveness of decontamination by water cleaning and by electrocleaning, and swipe effectiveness on the metal surfaces were studied. A variety of environmental conditions had been manipulated to stimulate the potential 'weeping' phenomenon that often occurs with spent fuel shipping casks during transit. In a previous study, few heterogeneous effects of adsorbed contamination onto metal surfaces were observed. Radiographic images of cask surfaces were made in this study and showed clearly heterogeneous activity distributions. Acquired radiographic images were digitized and further analyzed with an image analysis computer package and compared to calibrated images by using standard sources. The measurements of activity distribution by using the radiographic image method were consistent with that using a HPGe detector. This radiographic image method was used to study the effects of electrocleaning for total and specified areas. The Modulation Transfer Function (MTF) of a film-screen system in contact with a radioactive metal surface was studied with neutron activated gold foils and showed more broad resolution properties than general diagnostic x-ray film-screen systems. Microstructure between normal areas and hot spots showed significant differences, and one hot spot appearing as a dot on the film image consisted of several small hot spots (about 10 μm in diameter). These hot spots were observed as structural defects of the metal surfaces.

Conceptual Design of In-Space Vehicles for Human Exploration of the Outer Planets

NASA Technical Reports Server (NTRS)

Adams, R. B.; Alexander, R. A.; Chapman, J. M.; Fincher, S. S.; Hopkins, R. C.; Philips, A. D.; Polsgrove, T. T.; Litchford, R. J.; Patton, B. W.; Statham, G.

2003-01-01

During FY-2002, a team of engineers from TD30/Advanced Concepts and TD40/Propulsion Research Center embarked on a study of potential crewed missions to the outer solar system. The study was conducted under the auspices of the Revolutionary Aerospace Systems Concepts activity administered by Langley Research Center (LaRC). The Marshall Space Flight Center (MSFC) team interacted heavily with teams from other Centers including Glenn Research Center, LaRC, Jet Propulsion Laboratory, and Johnson Space Center. The MSFC team generated five concept missions for this project. The concept missions use a variety of technologies, including magnetized target fusion (MTF), magnetoplasmadynamic thrusters, solid core reactors, and molten salt reactors in various combinations. The Technical Publication (TP) reviews these five concepts and the methods used to generate them. The analytical methods used are described for all significant disciplines and subsystems. The propulsion and power technologies selected for each vehicle are reviewed in detail. The MSFC team also expended considerable effort refining the MTF concept for use with this mission. The results from this effort are also contained within this TP. Finally, the lessons learned from this activity are summarized in the conclusions section.

Cathode Ray Tube Displays

DTIC Science & Technology

1988-06-17

Two difinitions have been devised to quantify contrast. Contrast ratio is given by - L2CR= = L (1) in which L2 and Li are luminance measurements and L2...units, which are quantitative , well understood, and predictable, before the display hardware is built. The last advantage is economically important in...then estimate quantitatively the effect of the resultant MTF change on user performance. 10 The reader interested in probing MTF in further depth is

Tidewater Multi-Service Market Perspectives: Driving change through MTF and market-level assessment and strategies

DTIC Science & Technology

2011-01-25

The Quadruple Aim: Working Together, Achieving Success 2011 Military Health System Conference Driving change through MTF and market -level assessment...and strategies Tidewater Multi-Service Market Perspectives January 25, 2011 Rear Admiral A. Stocks, MC, USN Colonel E. Stone, MC, USAF...Colonel K. Gausman, NC, USA 1 Military Health System Conference Tidewater Multi-Service Market Report Documentation Page Form ApprovedOMB No. 0704-0188

Demographic Subgroup Trends among Adolescents in the Use of Various Licit and Illicit Drugs, 1975-2013. Monitoring the Future Occasional Paper Series. Paper 81

ERIC Educational Resources Information Center

Johnston, Lloyd D.; O'Malley, Patrick M.; Bachman, Jerald G.; Schulenberg, John E.; Miech, Richard A.

2014-01-01

This occasional paper presents national demographic subgroup trends for U.S. secondary school students in a series of figures and tables. It supplements two of four annual monographs from the Monitoring the Future (MTF) study, namely the "Overview of Key Findings" and "Volume I: Secondary School Students." MTF is funded by the…

Chromatin insulation by a transcriptional activator

PubMed Central

Sutter, Nathan B.; Scalzo, David; Fiering, Steven; Groudine, Mark; Martin, David I. K.

2003-01-01

In eukaryotic genomes, transcriptionally active regions are interspersed with silent chromatin that may repress genes in its vicinity. Chromatin insulators are elements that can shield a locus from repressive effects of flanking chromatin. Few such elements have been characterized in higher eukaryotes, but transcriptional activating elements are an invariant feature of active loci and have been shown to suppress transgene silencing. Hence, we have assessed the ability of a transcriptional activator to cause chromatin insulation, i.e., to relieve position effects at transgene integration sites in cultured cells. The transgene contained a series of binding sites for the metal-inducible transcriptional activator MTF, linked to a GFP reporter. Clones carrying single integrated transgenes were derived without selection for expression, and in most clones the transgene was silent. Induction of MTF resulted in transition of the transgene from the silent to the active state, prolongation of the active state, and a marked narrowing of the range of expression levels at different genomic sites. At one genomic site, prolonged induction of MTF resulted in suppression of transgene silencing that persisted after withdrawal of the induction stimulus. These results are consistent with MTF acting as a chromatin insulator and imply that transcriptional activating elements can insulate active loci against chromatin repression. PMID:12547916

Clinical characteristics of patients with gender identity disorder at a Japanese gender identity disorder clinic.

PubMed

Okabe, Nobuyuki; Sato, Toshiki; Matsumoto, Yosuke; Ido, Yumiko; Terada, Seishi; Kuroda, Shigetoshi

2008-01-15

The aim of this study was to examine the clinical characteristics of patients with gender identity disorder (GID) at a GID clinic in Japan. A total of 603 consecutive patients were evaluated at the GID clinic using clinical information and results of physical and neurological examinations. Using DSM-IV criteria, 579 patients (96.0%) were diagnosed with GID. Four patients were excluded for transvestic fetishism, eight for homosexuality, five for schizophrenia, three for personality disorders, and four for other psychiatric disorders. Among the GID patients, 349 (60.3%) were the female-to-male (FTM) type, and 230 (39.7%) were the male-to-female (MTF) type. Almost all FTM-type GID patients started to feel discomfort with their sex before puberty and were sexually attracted to females. The proportion of FTM patients who had experienced marriage as a female was very low, and very few had children. Therefore, FTM-type GID patients seem to be highly homogeneous. On the other hand, various patterns of age at onset and sexual attraction existed among MTF patients. Among the MTF-type GID patients, 28.3% had married as males and 18.7% had sired children. Thus, MTF-type GID patients seem to be more heterogeneous.

One-dimensional MHD simulations of MTF systems with compact toroid targets and spherical liners

NASA Astrophysics Data System (ADS)

Khalzov, Ivan; Zindler, Ryan; Barsky, Sandra; Delage, Michael; Laberge, Michel

2017-10-01

One-dimensional (1D) MHD code is developed in General Fusion (GF) for coupled plasma-liner simulations in magnetized target fusion (MTF) systems. The main goal of these simulations is to search for optimal parameters of MTF reactor, in which spherical liquid metal liner compresses compact toroid plasma. The code uses Lagrangian description for both liner and plasma. The liner is represented as a set of spherical shells with fixed masses while plasma is discretized as a set of nested tori with circular cross sections and fixed number of particles between them. All physical fields are 1D functions of either spherical (liner) or small toroidal (plasma) radius. Motion of liner and plasma shells is calculated self-consistently based on applied forces and equations of state. Magnetic field is determined by 1D profiles of poloidal and toroidal fluxes - they are advected with shells and diffuse according to local resistivity, this also accounts for flux leakage into the liner. Different plasma transport models are implemented, this allows for comparison with ongoing GF experiments. Fusion power calculation is included into the code. We performed a series of parameter scans in order to establish the underlying dependencies of the MTF system and find the optimal reactor design point.

How Question Types Reveal Student Thinking: An Experimental Comparison of Multiple-True-False and Free-Response Formats

PubMed Central

Hubbard, Joanna K.; Potts, Macy A.; Couch, Brian A.

2017-01-01

Assessments represent an important component of undergraduate courses because they affect how students interact with course content and gauge student achievement of course objectives. To make decisions on assessment design, instructors must understand the affordances and limitations of available question formats. Here, we use a crossover experimental design to identify differences in how multiple-true-false (MTF) and free-response (FR) exam questions reveal student thinking regarding specific conceptions. We report that correct response rates correlate across the two formats but that a higher percentage of students provide correct responses for MTF questions. We find that MTF questions reveal a high prevalence of students with mixed (correct and incorrect) conceptions, while FR questions reveal a high prevalence of students with partial (correct and unclear) conceptions. These results suggest that MTF question prompts can direct students to address specific conceptions but obscure nuances in student thinking and may overestimate the frequency of particular conceptions. Conversely, FR questions provide a more authentic portrait of student thinking but may face limitations in their ability to diagnose specific, particularly incorrect, conceptions. We further discuss an intrinsic tension between question structure and diagnostic capacity and how instructors might use multiple formats or hybrid formats to overcome these obstacles. PMID:28450446

Examination of the dental cone-beam CT equipped with flat-panel-detector (FPD)

NASA Astrophysics Data System (ADS)

Ito, Rieko; Fujita, Naotoshi; Kodera, Yoshie

2011-03-01

In dentistry, computed tomography (CT) is essential for diagnosis. Recently, cone-beam CT has come into use. We used an "Alphard 3030" cone-beam CT equipped with an FPD system. This system can obtain fluoroscopic and CT images. Moreover, the Alphard has 4 exposure modes for CT, and each mode has a different field of view (FOV) and voxel size. We examined the image quality of kinetic and CT images obtained using the cone-beam CT system. To evaluate kinetic image quality, we calculated the Wiener spectrum (WS) and modulation transfer function (MTF). We then analyzed the lag images and exposed a phantom. To evaluate CT image quality, we calculated WS and MTF at various places in the FOV and examined the influence of extension of the cone beam X-ray on voxel size. Furthermore, we compared the WS and MTF values of cone-beam CT to those of another CT system. Evaluation of the kinetic images showed that cone-beam CT is sufficient for clinical diagnosis and provides better image quality than the other system tested. However, during exposure of a CT image, the distance from the center influences image quality (especially MTF). Further, differences in voxel size affect image quality. It is therefore necessary to carefully position the region of interest and select an appropriate mode.

Final Report on Development of Optimized Field-Reversed Configuration Plasma Formation Techniques for Magnetized Target Fusion

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

Lynn, Alan

2013-11-01

The University of New Mexico (UNM) proposed a collaboration with Los Alamos National Laboratory (LANL) to develop and test methods for improved formation of field-reversed configuration (FRC) plasmas relevant to magnetized target fusion (MTF) energy research. MTF is an innovative approach for a relatively fast and cheap path to the production of fusion energy that utilizes magnetic confinement to assist in the compression of a hot plasma to thermonuclear conditions by an external driver. LANL is currently pursing demonstration of the MTF concept via compression of an FRC plasma by a metal liner z-pinch in conjunction with the Air Forcemore » Research Laboratory in Albuquerque, NM. A key physics issue for the FRC's ultimate success as an MTF target lies in the initial pre-ionization (PI) stage. The PI plasma sets the initial conditions from which the FRC is created. In particular, the PI formation process determines the amount of magnetic flux that can be trapped to form the FRC. A ringing theta pinch ionization (RTPI) technique, such as currently used by the FRX-L device at LANL, has the advantages of high ionization fraction, simplicity (since no additional coils are required), and does not require internal electrodes which can introduce impurities into the plasma. However RTPI has been shown to only trap 50% of the initial bias flux at best and imposes additional engineering constraints on the capacitor banks. The amount of trapped flux plays an important role in the FRC's final equilibrium, transport, and stability properties, and provides increased ohmic heating of the FRC through induced currents as the magnetic field decays. Increasing the trapped flux also provides the route to greatest potential gains in FRC lifetime, which is essential to provide enough time to translate and compress the FRC effectively. In conjunction with LANL we initially planned to develop and test a microwave break- down system to improve the initial PI plasma formation. The UNM team would design the microwave optics and oversee the fabrication and assembly of all components and assist with integration into the FRX-L machine control system. LANL would provide a preexisting 65 kW X-band microwave source and some associated waveguide hardware. Once constructed and installed, UNM would take the lead in operating the microwave breakdown system and conducting studies to optimize its use in FRC PI formation in close cooperation with the needs of the LANL MTF team. In conjunction with our LANL collaborators, we decided after starting the project to switch from a microwave plasma breakdown approach to a plasma gun technology to use for enhanced plasma formation in the FRX-L field-reversed configuration experiment at LANL. Plasma guns would be able to provide significantly higher density plasma with greater control over its distribution in time and space within the experiment. This would allow greater control and ne-tuning of the PI plasma formed in the experiment. Multiple plasma guns would be employed to fill a Pyrex glass test chamber (built at UNM) with plasma which would then be characterized and optimized for the MTF effort.« less

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

Rottmann, J; Myronakis, M; Hu, Y

Purpose: Beams-eye-view imaging applications such as real-time soft-tissue motion estimation and MV-CBCT are hindered by the inherently low image contrast of electronic portal imaging devices (EPID) currently in clinical use. We investigate a cost effective scintillating glass that provides substantially increased detective quantum efficiency (DQE) and contrast to noise ratio (CNR). Methods: A pixelated scintillator prototype was built from LKH-5 glass. The array is 12mm thick; 42.4×42.4cm2 wide and features 1.51mm pixel pitch with 20µm separation (glue+septa). The LKH-5 array was mounted on the active matrix flat panel imager (AMPFI) of an AS-1200 (Varian) with the GdO2S2:Tb removed. A secondmore » AS-1200 was utilized as reference detector. The prototype EPID was characterized in terms of CNR, modulation transfer function (MTF) and DQE. Additionally, the visibility of various fiducial markers typically used in the clinic as well as a realistic 3D-printed lung tumor model was assessed. All items were placed in a 12cm thick solid water phantom. CNR is estimated using a Las Vegas contrast phantom, presampled MTF is estimated using a slanted slit technique and the DQE is calculated from measured normalized noise power spectra (NPS) and the MTF. Results: DQE(0) for the LKH-5 prototype increased by a factor of 8× to about 10%, compared to the AS-1200 equipped with its standard GdO2S2:Tb scintillator. CNR increased by a factor of 5.3×. Due to the pixel size the MTF50 decreased by about 55% to 0.23lp/mm. The visibility of all fiducial markers as well as the tumor model were however markedly improved in comparison to an acquisition with the same parameters using the GdO2S2:Tb scintillator. Conclusion: LKH-5 scintillating glasses allow the cost effective construction of thick pixelated scintillators for portal imaging which can yield a substantial increase in DQE and CNR. Soft tissue and fiducial marker visibility was found to be markedly improved. The project was supported in part by NIH grant R01CA188446-01 and a grant from Varian Medical Systems.« less

Comparative expression analysis of immune-related factors in the sea cucumber Apostichopus japonicus.

PubMed

Jiang, Jingwei; Zhou, Zunchun; Dong, Ying; Zhao, Zelong; Sun, Hongjuan; Wang, Bai; Jiang, Bei; Chen, Zhong; Gao, Shan

2018-01-01

In order to preliminarily explore the joint involvement of different immune-related factors during the same immune process in Apostichopus japonicus, the transcriptional expression of Cu/Zn superoxide dismutase (Cu/Zn-SOD), catalase (CAT), c-type lysozyme (c-LYZ), i-type lysozyme (i-LYZ), cathepsin D, melanotransferrin (MTF), Toll, c-type lectin (c-LCT) and complement 3 (C3) during the development from fertilized eggs to juveniles and after challenging the juveniles with Vibrio splendidus, Pseudoalteromonas nigrifaciens, Shewanella baltica and Bacillus cereus, respectively, was measured using the method of quantitative real-time PCR (qRT-PCR), and then the correlations among different immune-related factors were analyzed. The results showed that the selected immune-related factors were expressed at all of the determined developmental stages and significantly up-regulated at doliolaria stage, suggesting the selected factors are indispensable immune components and the immune system might be broadly activated at doliolaria stage in A. japonicus. After challenged with four pathogenic bacteria, Cu/Zn-SOD, CAT, i-LYZ, cathepsin D, MTF, Toll, C3 were all significantly down-regulated at 4 h, indicating that some components of A. japonicus immune system might be inhibited at the beginning of pathogenic bacteria invasion. The immune-responsive analysis also showed that the significant regulation in Toll after challenged with four tested bacteria, that in MTF after challenged with S. baltica and that in C3 after challenged with P. nigrifaciens were all minus, suggesting Toll, MTF and C3 are probably the primary targets of pathogenic bacteria attack. Furthermore, the correlation analysis indicated that, all of the selected immune-related factors except cathepsin D might be in the same immune regulatory network during A. japonicus development, while all of the selected immune-related factors except c-LYZ might be in the same responsive regulatory network after challenged with four pathogenic bacteria. Altogether, A. japonicus immune system exhibited high complexity in regulation during organism development and after bacterial challenges. Copyright © 2017 Elsevier Ltd. All rights reserved.

WE-D-18A-04: How Iterative Reconstruction Algorithms Affect the MTFs of Variable-Contrast Targets in CT Images

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

Dodge, C.T.; Rong, J.; Dodge, C.W.

2014-06-15

Purpose: To determine how filtered back-projection (FBP), adaptive statistical (ASiR), and model based (MBIR) iterative reconstruction algorithms affect the measured modulation transfer functions (MTFs) of variable-contrast targets over a wide range of clinically applicable dose levels. Methods: The Catphan 600 CTP401 module, surrounded by an oval, fat-equivalent ring to mimic patient size/shape, was scanned on a GE HD750 CT scanner at 1, 2, 3, 6, 12 and 24 mGy CTDIvol levels with typical patient scan parameters: 120kVp, 0.8s, 40mm beam width, large SFOV, 2.5mm thickness, 0.984 pitch. The images were reconstructed using GE's Standard kernel with FBP; 20%, 40% andmore » 70% ASiR; and MBIR. A task-based MTF (MTFtask) was computed for six cylindrical targets: 2 low-contrast (Polystyrene, LDPE), 2 medium-contrast (Delrin, PMP), and 2 high-contrast (Teflon, air). MTFtask was used to compare the performance of reconstruction algorithms with decreasing CTDIvol from 24mGy, which is currently used in the clinic. Results: For the air target and 75% dose savings (6 mGy), MBIR MTFtask at 5 lp/cm measured 0.24, compared to 0.20 for 70% ASiR and 0.11 for FBP. Overall, for both high-contrast targets, MBIR MTFtask improved with increasing CTDIvol and consistently outperformed ASiR and FBP near the system's Nyquist frequency. Conversely, for Polystyrene at 6 mGy, MBIR (0.10) and 70% ASiR (0.07) MTFtask was lower than for FBP (0.18). For medium and low-contrast targets, FBP remains the best overall algorithm for improved resolution at low CTDIvol (1–6 mGy) levels, whereas MBIR is comparable at higher dose levels (12–24 mGy). Conclusion: MBIR improved the MTF of small, high-contrast targets compared to FBP and ASiR at doses of 50%–12.5% of those currently used in the clinic. However, for imaging low- and mediumcontrast targets, FBP performed the best across all dose levels. For assessing MTF from different reconstruction algorithms, task-based MTF measurements are necessary.« less

TU-E-BRA-05: Reverse Geometry Imaging with MV Detector for Improved Image Resolution.

PubMed

Ganguly, A; Abel, E; Sun, M; Fahrig, R; Virshup, G; Star-Lack, J

2012-06-01

Thick pixilated scintillators can offer significant improvements in quantum efficiency over phosphor screen megavoltage (MV) detectors. However spatial resolution can be compromised due to the spreading of light across pixels within septa. Of particular interest are the lower energy x-ray photons and associated light photons that produce higher image contrast but are stopped near the scintillator entrance surface. They suffer the most scattering in the scintillator prior to detection in the photodiodes. Reversing the detector geometry, so that the incident x-ray beam passes through the photodiode array into the scintillator, allows the light to scatter less prior to detection. This also reduces the Swank noise since now higher and lower energy x-ray photons tend to produce similar electronic signals. In this work, we present simulations and measurements of detector MTF for the conventional/forward and reverse geometries to demonstrate this phenomenon. A tabletop system consisting of a Varian CX1 1MeV linear accelerator and a modified Varian Paxscan4030 with the readout electronics moved away from the incident the beam was used. A special holder was used to press a 2.5W×5.0L×2.0Hcm 3 pixellated Cesium Iodide (CsI:Tl) scintillator array on to the detector glass. The CsI array had a pitch of 0.784mm with plastic septa between pixels and the photodiode array pitch was 0.192 mm. The MTF in the forward and reverse geometries was measured using a 0.5mm thick Tantalum slanted edge. Geant4-based Monte Carlo simulations were performed for comparison. The measured and simulated MTFs matched to within 3.4(±3.7)% in the forward and 4.4(±1.5)% in reverse geometries. The reverse geometry MTF was higher than the forward geometry MTF at all spatial frequencies and doubled to .25 at 0.3lp/mm. A novel method of improving the image resolution at MV energies was demonstrated. The improvements should be more pronounced with increased scintillator thickness. Funding support provided by NIH (grant number NIH R01 CA138426). © 2012 American Association of Physicists in Medicine.

Evaluate depth of field limits of fixed focus lens arrangements in thermal infrared

NASA Astrophysics Data System (ADS)

Schuster, Norbert

2016-05-01

More and more modern thermal imaging systems use uncooled detectors. High volume applications work with detectors that have a reduced pixel count (typically between 200x150 and 640x480). This reduces the usefulness of modern image treatment procedures such as wave front coding. On the other hand, uncooled detectors demand lenses with fast fnumbers, near f/1.0, which reduces the expected Depth of Field (DoF). What are the limits on resolution if the target changes distance to the camera system? The desire to implement lens arrangements without a focusing mechanism demands a deeper quantification of the DoF problem. A new approach avoids the classic "accepted image blur circle" and quantifies the expected DoF by the Through Focus MTF of the lens. This function is defined for a certain spatial frequency that provides a straightforward relation to the pixel pitch of imaging device. A certain minimum MTF-level is necessary so that the complete thermal imaging system can realize its basic functions, such as recognition or detection of specified targets. Very often, this technical tradeoff is approved with a certain lens. But what is the impact of changing the lens for one with a different focal length? Narrow field lenses, which give more details of targets in longer distances, tighten the DoF problem. A first orientation is given by the hyperfocal distance. It depends in a square relation on the focal length and in a linear relation on the through focus MTF of the lens. The analysis of these relations shows the contradicting requirements between higher thermal and spatial resolution, faster f-number and desired DoF. Furthermore, the hyperfocal distance defines the DoF-borders. Their relation between is such as the first order imaging formulas. A calculation methodology will be presented to transfer DoF-results from an approved combination lens and camera to another lens in combination with the initial camera. Necessary input for this prediction is the accepted DoF of the initial combination and the through focus MTFs of both lenses. The accepted DoF of the initial combination defines an application and camera related MTF-level, which must be provided also by the new lens. Examples are provided. The formula of the Diffraction-Limited-Through-Focus-MTF (DLTF) quantifies the physical limit and works without any ray trace. This relation respects the pixel pitch, the waveband and the aperture based f-number, but is independent of detector size. The DLTF has a steeper slope than the ray traced Through-Focus-MTF; its maximum is the diffraction limit. The DLTF predicts the DoF-relations quite precisely. Differences to ray trace results are discussed. Last calculations with modern detectors show that a static chosen MTF-level doesn't reflect the reality for the DoFproblem. The MTF-level to respect depends on application, pixel pitch, IR-camera and image treatment. A value of 0.250 at the detector Nyquist frequency seems to be a reasonable starting point for uncooled FPAs with 17μm pixel pitch.

Simultaneous deblurring and iterative reconstruction of CBCT for image guided brain radiosurgery.

PubMed

Hashemi, SayedMasoud; Song, William Y; Sahgal, Arjun; Lee, Young; Huynh, Christopher; Grouza, Vladimir; Nordström, Håkan; Eriksson, Markus; Dorenlot, Antoine; Régis, Jean Marie; Mainprize, James G; Ruschin, Mark

2017-04-07

One of the limiting factors in cone-beam CT (CBCT) image quality is system blur, caused by detector response, x-ray source focal spot size, azimuthal blurring, and reconstruction algorithm. In this work, we develop a novel iterative reconstruction algorithm that improves spatial resolution by explicitly accounting for image unsharpness caused by different factors in the reconstruction formulation. While the model-based iterative reconstruction techniques use prior information about the detector response and x-ray source, our proposed technique uses a simple measurable blurring model. In our reconstruction algorithm, denoted as simultaneous deblurring and iterative reconstruction (SDIR), the blur kernel can be estimated using the modulation transfer function (MTF) slice of the CatPhan phantom or any other MTF phantom, such as wire phantoms. The proposed image reconstruction formulation includes two regularization terms: (1) total variation (TV) and (2) nonlocal regularization, solved with a split Bregman augmented Lagrangian iterative method. The SDIR formulation preserves edges, eases the parameter adjustments to achieve both high spatial resolution and low noise variances, and reduces the staircase effect caused by regular TV-penalized iterative algorithms. The proposed algorithm is optimized for a point-of-care head CBCT unit for image-guided radiosurgery and is tested with CatPhan phantom, an anthropomorphic head phantom, and 6 clinical brain stereotactic radiosurgery cases. Our experiments indicate that SDIR outperforms the conventional filtered back projection and TV penalized simultaneous algebraic reconstruction technique methods (represented by adaptive steepest-descent POCS algorithm, ASD-POCS) in terms of MTF and line pair resolution, and retains the favorable properties of the standard TV-based iterative reconstruction algorithms in improving the contrast and reducing the reconstruction artifacts. It improves the visibility of the high contrast details in bony areas and the brain soft-tissue. For example, the results show the ventricles and some brain folds become visible in SDIR reconstructed images and the contrast of the visible lesions is effectively improved. The line-pair resolution was improved from 12 line-pair/cm in FBP to 14 line-pair/cm in SDIR. Adjusting the parameters of the ASD-POCS to achieve 14 line-pair/cm caused the noise variance to be higher than the SDIR. Using these parameters for ASD-POCS, the MTF of FBP and ASD-POCS were very close and equal to 0.7 mm -1 which was increased to 1.2 mm -1 by SDIR, at half maximum.

Simultaneous deblurring and iterative reconstruction of CBCT for image guided brain radiosurgery

NASA Astrophysics Data System (ADS)

Hashemi, SayedMasoud; Song, William Y.; Sahgal, Arjun; Lee, Young; Huynh, Christopher; Grouza, Vladimir; Nordström, Håkan; Eriksson, Markus; Dorenlot, Antoine; Régis, Jean Marie; Mainprize, James G.; Ruschin, Mark

2017-04-01

One of the limiting factors in cone-beam CT (CBCT) image quality is system blur, caused by detector response, x-ray source focal spot size, azimuthal blurring, and reconstruction algorithm. In this work, we develop a novel iterative reconstruction algorithm that improves spatial resolution by explicitly accounting for image unsharpness caused by different factors in the reconstruction formulation. While the model-based iterative reconstruction techniques use prior information about the detector response and x-ray source, our proposed technique uses a simple measurable blurring model. In our reconstruction algorithm, denoted as simultaneous deblurring and iterative reconstruction (SDIR), the blur kernel can be estimated using the modulation transfer function (MTF) slice of the CatPhan phantom or any other MTF phantom, such as wire phantoms. The proposed image reconstruction formulation includes two regularization terms: (1) total variation (TV) and (2) nonlocal regularization, solved with a split Bregman augmented Lagrangian iterative method. The SDIR formulation preserves edges, eases the parameter adjustments to achieve both high spatial resolution and low noise variances, and reduces the staircase effect caused by regular TV-penalized iterative algorithms. The proposed algorithm is optimized for a point-of-care head CBCT unit for image-guided radiosurgery and is tested with CatPhan phantom, an anthropomorphic head phantom, and 6 clinical brain stereotactic radiosurgery cases. Our experiments indicate that SDIR outperforms the conventional filtered back projection and TV penalized simultaneous algebraic reconstruction technique methods (represented by adaptive steepest-descent POCS algorithm, ASD-POCS) in terms of MTF and line pair resolution, and retains the favorable properties of the standard TV-based iterative reconstruction algorithms in improving the contrast and reducing the reconstruction artifacts. It improves the visibility of the high contrast details in bony areas and the brain soft-tissue. For example, the results show the ventricles and some brain folds become visible in SDIR reconstructed images and the contrast of the visible lesions is effectively improved. The line-pair resolution was improved from 12 line-pair/cm in FBP to 14 line-pair/cm in SDIR. Adjusting the parameters of the ASD-POCS to achieve 14 line-pair/cm caused the noise variance to be higher than the SDIR. Using these parameters for ASD-POCS, the MTF of FBP and ASD-POCS were very close and equal to 0.7 mm-1 which was increased to 1.2 mm-1 by SDIR, at half maximum.

Demographic Subgroup Trends among Adolescents in the Use of Various Licit and Illicit Drugs, 1975-2015. Monitoring the Future Occasional Paper Series. Paper 86

ERIC Educational Resources Information Center

Johnston, Lloyd D.; O'Malley, Patrick M.; Miech, Richard A.; Bachman, Jerald G.; Schulenberg, John E.

2016-01-01

This occasional paper presents national demographic subgroup data for the 1975-2015 Monitoring the Future (MTF) national survey results on 8th, 10th, and 12th graders' use of drugs, alcohol, and tobacco. MTF is funded by the National Institute on Drug Abuse at the National Institutes of Health under a series of investigator-initiated, competitive…

Demographic Subgroup Trends among Adolescents in the Use of Various Licit and Illicit Drugs, 1975-2014. Monitoring the Future Occasional Paper Series. Paper 83

ERIC Educational Resources Information Center

Johnston, Lloyd D.; O'Malley, Patrick M.; Miech, Richard A.; Bachman, Jerald G.; Schulenberg, John E.

2015-01-01

This occasional paper presents national demographic subgroup data for the 1975-2014 Monitoring the Future (MTF) national survey results on 8th, 10th, and 12th graders' use of drugs, alcohol, and tobacco. MTF is funded by the National Institute on Drug Abuse at the National Institutes of Health under a series of investigator-initiated, competitive…

Demographic Subgroup Trends among Adolescents in the Use of Various Licit and Illicit Drugs, 1975-2016. Monitoring the Future Occasional Paper Series. Paper 88

ERIC Educational Resources Information Center

Johnston, Lloyd D.; O'Malley, Patrick M.; Miech, Richard A.; Bachman, Jerald G.; Schulenberg, John E.

2017-01-01

This occasional paper presents national demographic subgroup data for the 1975-2016 Monitoring the Future (MTF) national survey results on 8th , 10th, and 12th graders' use of drugs, alcohol, and tobacco. MTF is funded by the National Institute on Drug Abuse at the National Institutes of Health under a series of investigator-initiated, competitive…

Using Time-Phased Casualty Estimates to Determine Medical Resupply Requirements

DTIC Science & Technology

2006-09-18

calculated from the list of tasks. The RSVP-planned MTF laydown would be replaced by the reporting MTF with a known location. One advantage of...Another advantage is the ability to adapt quickly to changing requirements. Supplies that are used at a faster than initially forecast rate will...Officer ( GMO ) Platforms. San Diego, Calif: Naval Health Research Center; 2001. Technical Report No. 01-18. 5. Galarneau MR, Pang G, Konoske PJ

Implementation of the Asthma Practice Guideline in the Army Medical Department: Evaluation of Process and Effects

DTIC Science & Technology

2005-01-01

Summary xxv their knowledge and to train newly arrived providers who rotated in from previous MTF assignments. Patient Education . The provision of... patient education on self- care was one of the weaker components of the implementation activi- ties. Patient behaviors affect the MTFs’ ability to...and severity of asthma exacerbations. Inadequacies in MTF patient education activities were identified, including problems with program design, limited

Computational modeling of joint U.S.-Russian experiments relevant to magnetic compression/magnetized target fusion (MAGO/MTF)

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

Sheehey, P.T.; Faehl, R.J.; Kirkpatrick, R.C.

1997-12-31

Magnetized Target Fusion (MTF) experiments, in which a preheated and magnetized target plasma is hydrodynamically compressed to fusion conditions, present some challenging computational modeling problems. Recently, joint experiments relevant to MTF (Russian acronym MAGO, for Magnitnoye Obzhatiye, or magnetic compression) have been performed by Los Alamos National Laboratory and the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF). Modeling of target plasmas must accurately predict plasma densities, temperatures, fields, and lifetime; dense plasma interactions with wall materials must be characterized. Modeling of magnetically driven imploding solid liners, for compression of target plasmas, must address issues such as Rayleigh-Taylor instability growthmore » in the presence of material strength, and glide plane-liner interactions. Proposed experiments involving liner-on-plasma compressions to fusion conditions will require integrated target plasma and liner calculations. Detailed comparison of the modeling results with experiment will be presented.« less

Error analysis of the Golay3 optical imaging system.

PubMed

Wu, Quanying; Fan, Junliu; Wu, Feng; Zhao, Jun; Qian, Lin

2013-05-01

We use aberration theory to derive a generalized pupil function of the Golay3 imaging system when astigmatisms exist in its submirrors. Theoretical analysis and numerical simulation using ZEMAX show that the point spread function (PSF) and the modulation transfer function (MTF) of the Golay3 sparse aperture system have a periodic change when there are piston errors. When the peak-valley value of the wavefront (PV(tilt)) due to the tilt error increases from zero to λ, the PSF and the MTF change significantly, and the change direction is determined by the location of the submirror with the tilt error. When PV(tilt) becomes larger than λ, the PSF and the MTF remain unvaried. We calculate the peaks of the signal-to-noise ratio (PSNR) resulting from the piston and tilt errors according to the Strehl ratio, and show that the PSNR decreases when the errors increase.

High-MTF hybrid ferroelectric IRFPA

NASA Astrophysics Data System (ADS)

Evans, Scott B.; Hayden, Terrence

1998-07-01

Low cost, uncooled hybrid infrared focal plane arrays (IRFPA's) are in full-scale production at Raytheon Systems Company (RSC), formerly Texas Instruments Defense Systems and Electronics Group. Detectors consist of reticulated ceramic barium strontium titanate (BST) arrays of 320 X 240 pixels on 48.5 micrometer pitch. The principal performance shortcoming of the hybrid arrays has been low MTF due to thermal crosstalk between pixels. In the past two years, significant improvements have been made to increase MTF making hybrids more competitive in performance with monolithic arrays. The improvements are (1) the reduction of the thickness of the IR absorbing layer electrode that maintains electrical continuity and increases thermal isolation between pixels, (2) reduction of the electrical crosstalk from the ROIC, and (3) development of a process to increase the thermal path-length between pixels called 'elevated optical coat.' This paper describes all three activities and their efficacy. Also discussed is the uncooled IRFPA production capability at RSC.

Comparison of analytic and iterative digital tomosynthesis reconstructions for thin slab objects

NASA Astrophysics Data System (ADS)

Yun, J.; Kim, D. W.; Ha, S.; Kim, H. K.

2017-11-01

For digital x-ray tomosynthesis of thin slab objects, we compare the tomographic imaging performances obtained from the filtered backprojection (FBP) and simultaneous algebraic reconstruction (SART) algorithms. The imaging performance includes the in-plane molulation-transfer function (MTF), the signal difference-to-noise ratio (SDNR), and the out-of-plane blur artifact or artifact-spread function (ASF). The MTF is measured using a thin tungsten-wire phantom, and the SDNR and the ASF are measured using a thin aluminum-disc phantom embedded in a plastic cylinder. The FBP shows a better MTF performance than the SART. On the contrary, the SART outperforms the FBP with regard to the SDNR and ASF performances. Detailed experimental results and their analysis results are described in this paper. For a more proper use of digital tomosynthesis technique, this study suggests to use a reconstuction algorithm suitable for application-specific purposes.

Severe Spastic Contractures and Diabetes Mellitus Independently Predict Subsequent Minimal Trauma Fractures Among Long-Term Care Residents.

PubMed

Lam, Kuen; Leung, Man Fuk; Kwan, Chi Wai; Kwan, Joseph

2016-11-01

The study aimed to examine the epidemiology of hypertonic contractures and its relationship with minimal trauma fracture (MTF), and to determine the incidence and predictors of (MTF) in long-term care residents. This was a longitudinal cohort study of prospectively collected data. Participants were followed from March 2007 to March 2016 or until death. A 300-bed long-term care hospital in Hong Kong. All long-term care residents who were in need of continuous medical and nursing care for their activities of daily living. Information on patients' demographic data, severe contracture defined as a decrease of 50% or more of the normal passive range of joint movement of the joint, and severe limb spasticity defined by the Modified Ashworth Scale higher than grade 3, medical comorbidities, functional status, cognitive status, nutritional status including body mass index and serum albumin, past history of fractures, were evaluated as potential risk factors for subsequent MTF. Three hundred ninety-six residents [148 males, mean ± standard deviation (SD), age = 79 ± 16 years] were included for analysis. The presence of severe contracture was highly prevalent among the study population: 91% of residents had at least 1 severe contracture, and 41% of residents had severe contractures involving all 4 limbs. Moreover, there were a significant proportion of residents who had severe limb spasticity with the elbow flexors (32.4%) and knee flexors (33.9%) being the most commonly involved muscles. Twelve residents (3%) suffered from subsequent MTF over a median follow-up of 33 (SD = 30) months. Seven out of these 12 residents died during the follow-up period, with a mean survival of 17.8 months (SD = 12.6) after the fracture event. The following 2 factors were found to independently predict subsequent MTF in a multivariate Cox regression: bilateral severe spastic knee contractures (hazard ratio = 16.5, P < .0001, confidence interval 4.8-56.4) and diabetes mellitus (hazard ratio = 4.0. P = .018, confidence interval 1.3-12.7). Severe spasticity and contractures are common morbidities in long-term care residents, and bilateral severe spastic knee contractures and diabetes mellitus are 2 independent predictors of subsequent MTF. Spasticity management and prevention of contractures, combined with educational programs for caregivers to identify the high-risk residents and apply proper handling techniques during routine care, may be helpful in reducing the risk of MTF in long-term care residents. Further large-scale longitudinal studies are needed to confirm these findings. Copyright © 2016 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

An alternative approach to depth of field which avoids the blur circle and uses the pixel pitch

NASA Astrophysics Data System (ADS)

Schuster, Norbert

2015-09-01

Modern thermal imaging systems apply more and more uncooled detectors. High volume applications work with detectors which have a reduced pixel count (typical between 200x150 and 640x480). This shrinks the application of modern image treatment procedures like wave front coding. On the other hand side, uncooled detectors demand lenses with fast F-numbers near 1.0. Which are the limits on resolution if the target to analyze changes its distance to the camera system? The aim to implement lens arrangements without any focusing mechanism demands a deeper quantification of the Depth of Field problem. The proposed Depth of Field approach avoids the classic "accepted image blur circle". It bases on a camera specific depth of focus which is transformed in the object space by paraxial relations. The traditional RAYLEIGH's -criterion bases on the unaberrated Point Spread Function and delivers a first order relation for the depth of focus. Hence, neither the actual lens resolution neither the detector impact is considered. The camera specific depth of focus respects a lot of camera properties: Lens aberrations at actual F-number, detector size and pixel pitch. The through focus MTF is the base of the camera specific depth of focus. It has a nearly symmetric course around the maximum of sharp imaging. The through focus MTF is considered at detector's Nyquist frequency. The camera specific depth of focus is this the axial distance in front and behind of sharp image plane where the through focus MTF is <0.25. This camera specific depth of focus is transferred in the object space by paraxial relations. It follows a general applicable Depth of Field diagram which could be applied to lenses realizing a lateral magnification range -0.05…0. Easy to handle formulas are provided between hyperfocal distance and the borders of the Depth of Field in dependence on sharp distances. These relations are in line with the classical Depth of Field-theory. Thermal pictures, taken by different IR-camera cores, illustrate the new approach. The quite often requested graph "MTF versus distance" choses the half Nyquist frequency as reference. The paraxial transfer of the through focus MTF in object space distorts the MTF-curve: hard drop at closer distances than sharp distance, smooth drop at further distances. The formula of a general Diffraction-Limited-Through-Focus-MTF (DLTF) is deducted. Arbitrary detector-lens combinations could be discussed. Free variables in this analysis are waveband, aperture based F-number (lens) and pixel pitch (detector). The DLTF- discussion provides physical limits and technical requirements. The detector development with pixel pitches smaller than captured wavelength in the LWIR-region generates a special challenge for optical design.

Study on the properties of infrared wavefront coding athermal system under several typical temperature gradient distributions

NASA Astrophysics Data System (ADS)

Cai, Huai-yu; Dong, Xiao-tong; Zhu, Meng; Huang, Zhan-hua

2018-01-01

Wavefront coding for athermal technique can effectively ensure the stability of the optical system imaging in large temperature range, as well as the advantages of compact structure and low cost. Using simulation method to analyze the properties such as PSF and MTF of wavefront coding athermal system under several typical temperature gradient distributions has directive function to characterize the working state of non-ideal temperature environment, and can effectively realize the system design indicators as well. In this paper, we utilize the interoperability of data between Solidworks and ZEMAX to simplify the traditional process of structure/thermal/optical integrated analysis. Besides, we design and build the optical model and corresponding mechanical model of the infrared imaging wavefront coding athermal system. The axial and radial temperature gradients of different degrees are applied to the whole system by using SolidWorks software, thus the changes of curvature, refractive index and the distance between the lenses are obtained. Then, we import the deformation model to ZEMAX for ray tracing, and obtain the changes of PSF and MTF in optical system. Finally, we discuss and evaluate the consistency of the PSF (MTF) of the wavefront coding athermal system and the image restorability, which provides the basis and reference for the optimal design of the wavefront coding athermal system. The results show that the adaptability of single material infrared wavefront coding athermal system to axial temperature gradient can reach the upper limit of temperature fluctuation of 60°C, which is much higher than that of radial temperature gradient.

Optical performance of toric intraocular lenses in the presence of decentration

PubMed Central

Zhang, Bin; Ma, Jin-Xue; Liu, Dan-Yan; Du, Ying-Hua; Guo, Cong-Rong; Cui, Yue-Xian

2015-01-01

AIM To evaluate the optical performance of toric intraocular lenses (IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned. METHODS Optical performances of toric T5 and SN60AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from 0° to 90°. The ratio of the modulation transfer function (MTF) between a decentered and a centered IOL (MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance. RESULTS Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased, whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentration ratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs. CONCLUSIONS Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position. PMID:26309871

Modulation transfer function assessment in parallel beam and fan beam collimators with square and cylindrical holes.

PubMed

Khorshidi, Abdollah; Ashoor, Mansour

2014-05-01

This study investigates modulation transfer function (MTF) in parallel beam (PB) and fan beam (FB) collimators using the Monte Carlo method with full width at half maximum (FWHM), square and circular-shaped holes, and scatter and penetration (S + P) components. A regulation similar to the lead-to-air ratio was used for both collimators to estimate output data. The hole pattern was designed to compare FB by PB parameters. The radioactive source in air and in a water phantom placed in front of the collimators was simulated using MCNP5 code. The test results indicated that the square holes in PB (PBs) had better FWHM than did the cylindrical (PBc) holes. In contrast, the cylindrical holes in the FB (FBc) had better FWHM than the square holes. In general, the resolution of FBc was better than that of the PBc in air and scatter mediums. The S + P decreased for all collimators as the distance from the source to the collimator surface (z) increased. The FBc had a lower S + P than FBs, but PBc had a higher S + P than PBs. Of the FB and PB collimators with the identical hole shapes, PBs had a smaller S + P than FBs, and FBc had a smaller S + P than PBc. The MTF value for the FB was greater than for the PB and had increased spatial frequency; the FBc had higher MTF than the FBs and PB collimators. Estimating the FB using PB parameters and diverse hole shapes may be useful in collimator design to improve the resolution and efficiency of SPECT images.

Final report on the Magnetized Target Fusion Collaboration

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

John Slough

Nuclear fusion has the potential to satisfy the prodigious power that the world will demand in the future, but it has yet to be harnessed as a practical energy source. The entry of fusion as a viable, competitive source of power has been stymied by the challenge of finding an economical way to provide for the confinement and heating of the plasma fuel. It is the contention here that a simpler path to fusion can be achieved by creating fusion conditions in a different regime at small scale (~ a few cm). One such program now under study, referred tomore » as Magnetized Target Fusion (MTF), is directed at obtaining fusion in this high energy density regime by rapidly compressing a compact toroidal plasmoid commonly referred to as a Field Reversed Configuration (FRC). To make fusion practical at this smaller scale, an efficient method for compressing the FRC to fusion gain conditions is required. In one variant of MTF a conducting metal shell is imploded electrically. This radially compresses and heats the FRC plasmoid to fusion conditions. The closed magnetic field in the target plasmoid suppresses the thermal transport to the confining shell, thus lowering the imploding power needed to compress the target. The undertaking to be described in this proposal is to provide a suitable target FRC, as well as a simple and robust method for inserting and stopping the FRC within the imploding liner. The timescale for testing and development can be rapidly accelerated by taking advantage of a new facility funded by the Department of Energy. At this facility, two inductive plasma accelerators (IPA) were constructed and tested. Recent experiments with these IPAs have demonstrated the ability to rapidly form, accelerate and merge two hypervelocity FRCs into a compression chamber. The resultant FRC that was formed was hot (T&ion ~ 400 eV), stationary, and stable with a configuration lifetime several times that necessary for the MTF liner experiments. The accelerator length was less than 1 meter, and the time from the initiation of formation to the establishment of the final equilibrium was less than 10 microseconds. With some modification, each accelerator was made capable of producing FRCs suitable for the production of the target plasma for the MTF liner experiment. Based on the initial FRC merging/compression results, the design and methodology for an experimental realization of the target plasma for the MTF liner experiment can now be defined. A high density FRC plasmoid is to be formed and accelerated out of each IPA into a merging/compression chamber similar to the imploding liner at AFRL. The properties of the resultant FRC plasma (size, temperature, density, flux, lifetime) are obtained in the reevant regime of interest. The process still needs to be optimized, and a final design for implementation at AFRL must now be carried out. When implemented at AFRL it is anticipated that the colliding/merging FRCs will then be compressed by the liner. In this manner it is hoped that ultimately a plasma with ion temperatures reaching the 10 keV range and fusion gain near unity can be obtained.« less

A new compartmental method for the analysis of liver FDG kinetics in small animal models.

PubMed

Garbarino, Sara; Vivaldi, Valentina; Delbary, Fabrice; Caviglia, Giacomo; Piana, Michele; Marini, Cecilia; Capitanio, Selene; Calamia, Iolanda; Buschiazzo, Ambra; Sambuceti, Gianmario

2015-12-01

Compartmental analysis is a standard method to quantify metabolic processes using fluorodeoxyglucose-positron emission tomography (FDG-PET). For liver studies, this analysis is complex due to the hepatocyte capability to dephosphorylate and release glucose and FDG into the blood. Moreover, a tracer is supplied to the liver by both the hepatic artery and the portal vein, which is not visible in PET images. This study developed an innovative computational approach accounting for the reversible nature of FDG in the liver and directly computing the portal vein tracer concentration by means of gut radioactivity measurements. Twenty-one mice were subdivided into three groups: the control group 'CTR' (n = 7) received no treatment, the short-term starvation group 'STS' (n = 7) was submitted to food deprivation with free access to water within 48 h before imaging, and the metformin group 'MTF' (n = 7) was treated with metformin (750 mg/Kg per day) for 1 month. All mice underwent a dynamic micro-PET study for 50 min after an (18)F-FDG injection. The compartmental analysis considered two FDG pools (phosphorylated and free) in both the gut and liver. A tracer was carried into the liver by the hepatic artery and the portal vein, and tracer delivery from the gut was considered as the sole input for portal vein tracer concentration. Accordingly, both the liver and gut were characterized by two compartments and two exchange coefficients. Each one of the two two-compartment models was mathematically described by a system of differential equations, and data optimization was performed by applying a Newton algorithm to the inverse problems associated to these differential systems. All rate constants were stable in each group. The tracer coefficient from the free to the metabolized compartment in the liver was increased by STS, while it was unaltered by MTF. By contrast, the tracer coefficient from the metabolized to the free compartment was reduced by MTF and increased by STS. Data demonstrated that our method was able to analyze FDG kinetics under pharmacological or pathophysiological stimulation, quantifying the fraction of the tracer trapped in the liver or dephosphorylated and released into the bloodstream.

Magnetized Target Fusion Collaboration. Final report

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

Slough, John

Nuclear fusion has the potential to satisfy the prodigious power that the world will demand in the future, but it has yet to be harnessed as a practical energy source. The entry of fusion as a viable, competitive source of power has been stymied by the challenge of finding an economical way to provide for the confinement and heating of the plasma fuel. It is the contention here that a simpler path to fusion can be achieved by creating fusion conditions in a different regime at small scale (~ a few cm). One such program now under study, referred tomore » as Magnetized Target Fusion (MTF), is directed at obtaining fusion in this high energy density regime by rapidly compressing a compact toroidal plasmoid commonly referred to as a Field Reversed Configuration (FRC). To make fusion practical at this smaller scale, an efficient method for compressing the FRC to fusion gain conditions is required. In one variant of MTF a conducting metal shell is imploded electrically. This radially compresses and heats the FRC plasmoid to fusion conditions. The closed magnetic field in the target plasmoid suppresses the thermal transport to the confining shell, thus lowering the imploding power needed to compress the target. The undertaking described in this report was to provide a suitable target FRC, as well as a simple and robust method for inserting and stopping the FRC within the imploding liner. The FRC must also survive during the time it takes for the metal liner to compress the FRC target. The initial work at the UW was focused on developing adequate preionization and flux trapping that were found to be essential in past experiments for obtaining the density, flux and most critically, FRC lifetime required for MTF. The timescale for testing and development of such a source can be rapidly accelerated by taking advantage of a new facility funded by the Department of Energy. At this facility, two inductive plasma accelerators (IPA) were constructed and tested. Recent experiments with these IPAs have demonstrated the ability to rapidly form, accelerate and merge two hypervelocity FRCs into a compression chamber. The resultant FRC that was formed was hot (T{sub ion} ~ 400 eV), stationary, and stable with a configuration lifetime several times that necessary for the MTF liner experiments. The accelerator length was less than 1 meter, and the time from the initiation of formation to the establishment of the final equilibrium was less than 10 microseconds. With some modification, each accelerator can be made capable of producing FRCs suitable for the production of the target plasma for the MTF liner experiment. Based on the initial FRC merging/compression results, the design and methodology for an experimental realization of the target plasma for the MTF liner experiment can now be defined. The construction and testing of the key components for the formation of the target plasma at the Air Force Research Laboratory (AFRL) will be performed on the IPA experiment, now at MSNW. A high density FRC plasmoid will be formed and accelerated out of each IPA into a merging/compression chamber similar to the imploding liner at AFRL. The properties of the resultant FRC plasma (size, temperature, density, flux, lifetime) will be obtained. The process will be optimized, and a final design for implementation at AFRL will be carried out. When implemented at AFRL it is anticipated that the colliding/merging FRCs will then be compressed by the liner. In this manner it is hoped that ultimately a plasma with ion temperatures reaching the 10 keV range and fusion gain near unity can be obtained.« less

Dual-energy imaging method to improve the image quality and the accuracy of dose calculation for cone-beam computed tomography.

PubMed

Men, Kuo; Dai, Jianrong; Chen, Xinyuan; Li, Minghui; Zhang, Ke; Huang, Peng

2017-04-01

To improve the image quality and accuracy of dose calculation for cone-beam computed tomography (CT) images through implementation of a dual-energy cone-beam computed tomography method (DE-CBCT), and evaluate the improvement quantitatively. Two sets of CBCT projections were acquired using the X-ray volumetric imaging (XVI) system on a Synergy (Elekta, Stockholm, Sweden) system with 120kV (high) and 70kV (low) X-rays, respectively. Then, the electron density relative to water (relative electron density (RED)) of each voxel was calculated using a projection-based dual-energy decomposition method. As a comparison, single-energy cone-beam computed tomography (SE-CBCT) was used to calculate RED with the Hounsfield unit-RED calibration curve generated by a CIRS phantom scan with identical imaging parameters. The imaging dose was measured with a dosimetry phantom. The image quality was evaluated quantitatively using a Catphan 503 phantom with the evaluation indices of the reproducibility of the RED values, high-contrast resolution (MTF 50% ), uniformity, and signal-to-noise ratio (SNR). Dose calculation of two simulated volumetric-modulated arc therapy plans using an Eclipse treatment-planning system (Varian Medical Systems, Palo Alto, CA, USA) was performed on an Alderson Rando Head and Neck (H&N) phantom and a Pelvis phantom. Fan-beam planning CT images for the H&N and Pelvis phantom were set as the reference. A global three-dimensional gamma analysis was used to compare dose distributions with the reference. The average gamma values for targets and OAR were analyzed with paired t-tests between DE-CBCT and SE-CBCT. In two scans (H&N scan and body scan), the imaging dose of DE-CBCT increased by 1.0% and decreased by 1.3%. It had a better reproducibility of the RED values (mean bias: 0.03 and 0.07) compared with SE-CBCT (mean bias: 0.13 and 0.16). It also improved the image uniformity (57.5% and 30.1%) and SNR (9.7% and 2.3%), but did not affect the MTF 50% . Gamma analyses of the 3D dose distribution with criteria of 1%/1mm showed a pass rate of 99.0-100% and 85.3-97.6% for DE-CBCT and 73.5-99.1% and 80.4-92.7% for SE-CBCT. The average gamma values were reduced significantly by DE-CBCT (p< 0.05). Gamma index maps showed that matching of the dose distribution between CBCT-based and reference was improved by DE-CBCT. DE-CBCT can achieve both better image quality and higher accuracy of dose calculation, and could be applied to adaptive radiotherapy. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

The Progress of Research Project for Magnetized Target Fusion in China

NASA Astrophysics Data System (ADS)

Yang, Xian-Jun

2015-11-01

The fusion of magnetized plasma called Magnetized Target Fusion (MTF) is a hot research area recently. It may significantly reduce the cost and size. Great progress has been achieved in past decades around the world. Five years ago, China initiated the MTF project and has gotten some progress as follows: 1. Verifying the feasibility of ignition of MTF by means of first principle and MHD simulation; 2. Generating the magnetic field over 1400 Tesla, which can be suppress the heat conduction from charged particles, deposit the energy of alpha particle to promote the ignition process, and produce the stable magnetized plasma for the target of ignition; 3. The imploding facility of FP-1 can put several Mega Joule energy to the solid liner of about ten gram in the range of microsecond risen time, while the simulating tool has been developed for design and analysis of the process; 4. The target of FRC can be generated by ``YG 1 facility'' while some simulating tools have be developed. Next five years, the above theoretical work and the experiments of MTF may be integrated to step up as the National project, which may make my term play an important lead role and be supposed to achieve farther progress in China. Supported by the National Natural Science Foundation of China under Grant No 11175028.

The dependence of the modulation transfer function on the blocking layer thickness in amorphous selenium x-ray detectors

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

Hunter, David M.; Belev, Gueorgi; DeCrescenzo, Giovanni

2007-08-15

Blocking layers are used to reduce leakage current in amorphous selenium detectors. The effect of the thickness of the blocking layer on the presampling modulation transfer function (MTF) and on dark current was experimentally determined in prototype single-line CCD-based amorphous selenium (a-Se) x-ray detectors. The sampling pitch of the detectors evaluated was 25 {mu}m and the blocking layer thicknesses varied from 1 to 51 {mu}m. The blocking layers resided on the signal collection electrodes which, in this configuration, were used to collect electrons. The combined thickness of the blocking layer and a-Se bulk in each detector was {approx}200 {mu}m. Asmore » expected, the dark current increased monotonically as the thickness of the blocking layer was decreased. It was found that if the blocking layer thickness was small compared to the sampling pitch, it caused a negligible reduction in MTF. However, the MTF was observed to decrease dramatically at spatial frequencies near the Nyquist frequency as the blocking layer thickness approached or exceeded the electrode sampling pitch. This observed reduction in MTF is shown to be consistent with predictions of an electrostatic model wherein the image charge from the a-Se is trapped at a characteristic depth within the blocking layer, generally near the interface between the blocking layer and the a-Se bulk.« less

Restoration of motion blurred image with Lucy-Richardson algorithm

NASA Astrophysics Data System (ADS)

Li, Jing; Liu, Zhao Hui; Zhou, Liang

2015-10-01

Images will be blurred by relative motion between the camera and the object of interest. In this paper, we analyzed the process of motion-blurred image, and demonstrated a restoration method based on Lucy-Richardson algorithm. The blur extent and angle can be estimated by Radon transform algorithm and auto-correlation function, respectively, and then the point spread function (PSF) of the motion-blurred image can be obtained. Thus with the help of the obtained PSF, the Lucy-Richardson restoration algorithm is used for experimental analysis on the motion-blurred images that have different blur extents, spatial resolutions and signal-to-noise ratios (SNR's). Further, its effectiveness is also evaluated by structural similarity (SSIM). Further studies show that, at first, for the image with a spatial frequency of 0.2 per pixel, the modulation transfer function (MTF) of the restored images can maintains above 0.7 when the blur extent is no bigger than 13 pixels. That means the method compensates low frequency information of the image, while attenuates high frequency information. At second, we fund that the method is more effective on condition that the product of the blur extent and spatial frequency is smaller than 3.75. Finally, the Lucy-Richardson algorithm is found insensitive to the Gaussian noise (of which the variance is not bigger than 0.1) by calculating the MTF of the restored image.

Culture-dependent enumeration methods failed to simultaneously detect disinfectant-injured and genetically modified Escherichia coli in drinking water.

PubMed

Li, Jing; Liu, Lu; Yang, Dong; Liu, Wei-Li; Shen, Zhi-Qiang; Qu, Hong-Mei; Qiu, Zhi-Gang; Hou, Ai-Ming; Wang, Da-Ning; Ding, Chen-Shi; Li, Jun-Wen; Guo, Jian-Hua; Jin, Min

2017-05-24

Underestimation of Escherichia coli in drinking water, an indicator microorganism of sanitary risk, may result in potential risks of waterborne diseases. However, the detection of disinfectant-injured or genetically modified (GM) E. coli has been largely overlooked so far. To evaluate the accuracy of culture-dependent enumeration with regard to disinfectant-injured and GM E. coli, chlorine- or ozone-injured wild-type (WT) and GM E. coli were prepared and characterized. Then, water samples contaminated with these E. coli strains were assayed by four widely used methods, including lactose tryptose broth-based multiple-tube fermentation (MTF), m-endo-based membrane filtration method (MFM), an enzyme substrate test (EST) known as Colilert, and Petrifilm-based testing slip method (TSM). It was found that MTF was the most effective method to detect disinfectant-injured WT E. coli (with 76.9% trials detecting all these bacteria), while this method could not effectively detect GM E. coli (with uninjured bacteria undetectable and a maximal detection rate of 21.5% for the injured). The EST was the only method which enabled considerable enumeration of uninjured GM E. coli, with a detection rate of over 93%. However, the detection rate declined to lower than 45.4% once the GM E. coli was injured by disinfectants. The MFM was invalid for both disinfectant-injured and GM E. coli. This is the first study to report the failure of these commonly used enumeration methods to simultaneously detect disinfectant-injured and GM E. coli. Thus, it highlights the urgent requirement for the development of a more accurate and versatile enumeration method which allows the detection of disinfectant-injured and GM E. coli on the assessment of microbial quality of drinking water.

Transgender transitioning and change of self-reported sexual orientation.

PubMed

Auer, Matthias K; Fuss, Johannes; Höhne, Nina; Stalla, Günter K; Sievers, Caroline

2014-01-01

Sexual orientation is usually considered to be determined in early life and stable in the course of adulthood. In contrast, some transgender individuals report a change in sexual orientation. A common reason for this phenomenon is not known. We included 115 transsexual persons (70 male-to-female "MtF" and 45 female-to-male "FtM") patients from our endocrine outpatient clinic, who completed a questionnaire, retrospectively evaluating the history of their gender transition phase. The questionnaire focused on sexual orientation and recalled time points of changes in sexual orientation in the context of transition. Participants were further asked to provide a personal concept for a potential change in sexual orientation. In total, 32.9% (n = 23) MtF reported a change in sexual orientation in contrast to 22.2% (n = 10) FtM transsexual persons (p = 0.132). Out of these patients, 39.1% (MtF) and 60% (FtM) reported a change in sexual orientation before having undergone any sex reassignment surgery. FtM that had initially been sexually oriented towards males ( = androphilic), were significantly more likely to report on a change in sexual orientation than gynephilic, analloerotic or bisexual FtM (p = 0.012). Similarly, gynephilic MtF reported a change in sexual orientation more frequently than androphilic, analloerotic or bisexual MtF transsexual persons (p =0.05). In line with earlier reports, we reveal that a change in self-reported sexual orientation is frequent and does not solely occur in the context of particular transition events. Transsexual persons that are attracted by individuals of the opposite biological sex are more likely to change sexual orientation. Qualitative reports suggest that the individual's biography, autogynephilic and autoandrophilic sexual arousal, confusion before and after transitioning, social and self-acceptance, as well as concept of sexual orientation itself may explain this phenomenon.

Impact of Sexual Orientation Identity on Medical Morbidities in Male-to-Female Transgender Patients.

PubMed

Gaither, Thomas W; Awad, Mohannad A; Osterberg, E Charles; Romero, Angelita; Bowers, Marci L; Breyer, Benjamin N

2017-02-01

We aim to describe the relationship between sexual orientation identity and medical morbidities in a large sample of male-to-female (MTF) transgender patients. We reviewed medical records of patients presenting for MTF sex reassignment surgery (SRS) by a single, high-volume surgeon from 2011 to 2015. Sexual attraction to men (heterosexual), women (lesbian), or both (bisexual) was asked of each patient. We examined 16 medical morbidities for this analysis. During the study period, 330 MTF transgender patients presented for SRS. The average age at the time of surgery was 38.9 (range 18-76). One hundred and one patients (32%) reported being heterosexual, 110 patients (34%) reported being lesbian, and 108 patients (34%) reported being bisexual. Lesbian patients presented for SRS at older ages (mean = 43 years old) compared with heterosexual patients (mean = 36 years old) and bisexual patients (mean = 37), P < 0.01. No differences were found in the majority of coexisting medical morbidities by sexual orientation identity. Lesbian patients had greater odds of having a history of depression, age-adjusted odds ratio (aOR) = 2.36, 95% confidence interval (CI) 1.26-4.40, compared with heterosexual patients. Lesbian patients had higher odds of being married or partnered, aOR = 2.31, 95% CI (1.27-4.19), compared with heterosexual patients. Heterosexual patients had higher odds of having human immunodeficiency virus (HIV), aOR = 9.07, 95% CI (1.08-76.5) compared with lesbian patients. Sexual orientation identity in MTF transgender patients is variable. The majority of medical morbidities are not associated with sexual orientation identity. Although HIV and depression are common morbidities among MTF patients seeking SRS, the prevalence of these morbidities differs by sexual orientation identity, but these findings need replication. Counseling and future research initiatives in transgender care should incorporate sexual orientation identity and associated risk behavior.

Interface healing and its correlation with visual recovery and quality of vision following small incision lenticule extraction.

PubMed

Ganesh, Sri; Brar, Sheetal; Pandey, Rahul; Pawar, Archana

2018-02-01

To study the time course of interface healing and its correlation with visual acuity, modulation transfer function (MTF), and aberrations after myopic small-incision lenticule extraction (SMILE) correction. Seventy-eight eyes of 78 patients (1 eye per patient) with a mean age of 25.7 years and mean spherical equivalent (SE) of -3.74D, undergoing bilateral SMILE procedure, were included in this study. On postoperative day 1, 2 weeks, and 3 months, dilated retroillumination photographs were taken and morphology of corneal interface was graded by comparing them with 5 standard templates representing 5 grades of interface roughness (IRG): IRG - 0 (clear), IRG - 1 (mild), IRG - 2 (moderate), IRG - 3 (severe), and IRG - 4 (severe IRG with Bowman's folds in visual axis). Pearson's correlations were computed to study correlation associations, and Wilcoxon signed-rank test was used for intragroup comparison of means. P ≤ 0.05 was considered statistically significant. At 3 months, 90.70% eyes were Grade 0 while 9.30% eyes still had Grade 2 interface granularity. Mean IRG significantly improved from 2.47 ± 0.57 at day 1 to 0.62 ± 0.53 at 3 months (P = 0.00). At day 1, pre-SE showed a significant positive correlation with IRG; however, mean postoperative corrected distant visual acuity (CDVA, in decimal), corneal Strehl ratio (SR), and MTF showed weak but significant negative correlation with IRG (r2 = 0.28 for SE, -0.052 for CDVA, -0.017 for SR, and -0.39 for MTF, respectively, P < 0.05 for all correlations). At 2 weeks and 3 months, corneal MTF continued to show a significant negative correlation, whereas other parameters did not show any correlation with IRG. Visual quality and corneal MTF may be significantly affected by the IRG in the immediate postoperative period after SMILE and may take 3 months or more for complete recovery.

Reinforcing the Military in Military Medicine: Driving a Cultural Change in Investigating, Tracking and Training to Prevent Patient Safety Events in Military Facilities

DTIC Science & Technology

2011-04-01

habits, and the complex nature of health care operations resulting from team efforts. Concerns about medical liability from medical malpractice ...investigations as blame is easier to assign to one individual than to evaluate the layers of an organization for failures. Medical malpractice fears...Risk Manager will brief the MTF/CC and Executive Staff on MTF medical malpractice claims semi-annually as well as discuss lessons learned, systemic

Coming Soon to an MTF Near You: Psychological Health Policy Initiatives

DTIC Science & Technology

2011-01-25

Force Health Protection and Readiness Coming Soon to an MTF Near You: Psychological Health Policy Initiatives 25 Jan 11 LCDR Nicole Frazer, Ph.D. & Dr...it does not display a currently valid OMB control number. 1. REPORT DATE 25 JAN 2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011...if a disaster were to occur next week? *U.S. Navy photo by Mass Communication Specialist 1st Class Carmichael Yepez, 5/12/10, Armona, CA 2011 MHS

Optimization and Comparison of Different Digital Mammographic Tomosynthesis Reconstruction Methods

DTIC Science & Technology

2007-04-01

physical measurements of impulse response analysis, modulation transfer function (MTF) and noise power spectrum (NPS). (Months 5- 12). 1.2.1. Simulate...added: projection images with simulated impulse and the 1/r2 shading difference. Other system blur and noise issues were not addressed in this paper...spectrum (NPS), Noise -equivalent quanta (NEQ), impulse response, Back Projection (BP) 1. INTRODUCTION Digital breast tomosynthesis is a new

Optimization and Comparison of Different Digital Mammographic Tomosynthesis Reconstruction Methods

DTIC Science & Technology

2008-04-01

physical measurements of impulse response analysis, modulation transfer function (MTF) and noise power spectrum (NPS). (Months 5- 12). This task has...and 2 impulse -added: projection images with simulated impulse and the I /r2 shading difference. Other system blur and noise issues are not...blur, and suppressed high frequency noise . Point-by-point BP rather than traditional SAA should be considered as the basis of further deblurring

High resolution MR based polymer dosimetry versus film densitometry: a systematic study based on the modulation transfer function approach.

PubMed

Berg, A; Pernkopf, M; Waldhäusl, C; Schmidt, W; Moser, E

2004-09-07

Precise methods of modem radiation therapy such as intensity modulated radiotherapy (IMRT), brachytherapy (BT) and high LET irradiation allow for high dose localization in volumes of a few mm3. However, most dosimetry methods-ionization chambers, TLD arrangements or silicon detectors, for example-are not capable of detecting sub-mm dose variations or do not allow for simple dose imaging. Magnetic resonance based polymer dosimetry (MRPD) appears to be well suited to three-dimensional high resolution relative dosimetry but the spatial resolution based on a systematic modulation transfer function (MTF) approach has not yet been investigated. We offer a theoretical construct for addressing the spatial resolution in different dose imaging systems, i.e. the dose modulation transfer function (DMTF) approach, an experimental realization of this concept with a phantom and quantitative comparisons between two dosimetric systems: polymer gel and film dosimetry. Polymer gel samples were irradiated by Co-60 photons through an absorber grid which is characterized by periodic structures of different spatial period (a), the smallest one at width of a/2 = 280 microm. The modulation in dose under the grid is visualized via calibrated, high resolution, parameter-selective (T2) and dose images based on multi-echo MR imaging. The DMTF is obtained from the modulation depth of the spin-spin relaxation time (T2) after calibration. Voxel sizes below 0.04 mm3 could be achieved, which are significantly smaller than those reported in MR based dose imaging on polymer gels elsewhere, using a powerful gradient system and a highly sensitive small birdcage resonator on a whole-body 3T MR scanner. Dose modulations at 22% of maximum dose amplitude could be observed at about 2 line pairs per mm. The polymer DMTF results are compared to those of a typical clinical film-scanner system. This study demonstrates that MR based gel dosimetry at 200 microm pixel resolution might even be superior, with reference to relative spatial resolution, to the results of a standard film-scanner system offering a nominal scan resolution of 200 microm.

Comparison of high resolution x-ray detectors with conventional FPDs using experimental MTFs and apodized aperture pixel design for reduced aliasing

NASA Astrophysics Data System (ADS)

Shankar, A.; Russ, M.; Vijayan, S.; Bednarek, D. R.; Rudin, S.

2017-03-01

Apodized Aperture Pixel (AAP) design, proposed by Ismailova et.al, is an alternative to the conventional pixel design. The advantages of AAP processing with a sinc filter in comparison with using other filters include non-degradation of MTF values and elimination of signal and noise aliasing, resulting in an increased performance at higher frequencies, approaching the Nyquist frequency. If high resolution small field-of-view (FOV) detectors with small pixels used during critical stages of Endovascular Image Guided Interventions (EIGIs) could also be extended to cover a full field-of-view typical of flat panel detectors (FPDs) and made to have larger effective pixels, then methods must be used to preserve the MTF over the frequency range up to the Nyquist frequency of the FPD while minimizing aliasing. In this work, we convolve the experimentally measured MTFs of an Microangiographic Fluoroscope (MAF) detector, (the MAF-CCD with 35μm pixels) and a High Resolution Fluoroscope (HRF) detector (HRF-CMOS50 with 49.5μm pixels) with the AAP filter and show the superiority of the results compared to MTFs resulting from moving average pixel binning and to the MTF of a standard FPD. The effect of using AAP is also shown in the spatial domain, when used to image an infinitely small point object. For detectors in neurovascular interventions, where high resolution is the priority during critical parts of the intervention, but full FOV with larger pixels are needed during less critical parts, AAP design provides an alternative to simple pixel binning while effectively eliminating signal and noise aliasing yet allowing the small FOV high resolution imaging to be maintained during critical parts of the EIGI.

Crystalline lens MTF measurement during simulated accommodation

NASA Astrophysics Data System (ADS)

Borja, David; Takeuchi, Gaku; Ziebarth, Noel; Acosta, Ana C.; Manns, Fabrice; Parel, Jean-Marie

2005-04-01

Purpose: To design and test an optical system to measure the optical quality of post mortem lenses during simulated accommodation. Methods: An optical bench top system was designed to measure the point spread function and calculate the modulation transfer function (MTF) of monkey and human ex-vivo crystalline lenses. The system consists of a super luminescent diode emitting at 850nm, collimated into a 3mm beam which is focused by the ex-vivo lens under test. The intensity distribution at the focus (point spread function) is re-imaged and magnified onto a beam profiler CCD camera. The optical quality in terms of spatial frequency response (modulation transfer function) is calculated by Fourier transform of the point spread function. The system was used on ex-vivo lenses with attached zonules, ciliary body and sclera. The sclera was glued to 8 separate PMMA segments and stretched radial by 5mm on an accommodation simulating lens stretching device. The point spread function was measured for each lens in the relaxed and stretched state for 5 human (ages 38-86 years) and 5 cynomolgus monkey (ages 53 - 67 months) fresh post mortem crystalline lenses. Results: Stretching induced measurable changes in the MTF. The cutoff frequency increased from 54.4+/-13.6 lp/mm unstretched to 59.5+/-21.4 lp/mm stretched in the post-presbyopic human and from 51.9+/-24.7 lp/mm unstretched to 57.7+/-18.5 lp/mm stretched cynomolgus monkey lenses. Conclusion: The results demonstrate the feasibility of measuring the optical quality of ex-vivo human and cynomolgus monkey lenses during simulated accommodation. Additional experiments are underway to quantify changes in optical quality induced by stretching.

Sci-Thur AM: YIS – 08: Automated Imaging Quality Assurance for Image-Guided Small Animal Irradiators

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

Johnstone, Chris; Bazalova-Carter, Magdalena

Purpose: To develop quality assurance (QA) standards and tolerance levels for image quality of small animal irradiators. Methods: A fully automated in-house QA software for image analysis of a commercial microCT phantom was created. Quantitative analyses of CT linearity, signal-to-noise ratio (SNR), uniformity and noise, geometric accuracy, modulation transfer function (MTF), and CT number evaluation was performed. Phantom microCT scans from seven institutions acquired with varying parameters (kVp, mA, time, voxel size, and frame rate) and five irradiator units (Xstrahl SARRP, PXI X-RAD 225Cx, PXI X-RAD SmART, GE explore CT/RT 140, and GE Explore CT 120) were analyzed. Multi-institutional datamore » sets were compared using our in-house software to establish pass/fail criteria for each QA test. Results: CT linearity (R2>0.996) was excellent at all but Institution 2. Acceptable SNR (>35) and noise levels (<55HU) were obtained at four of the seven institutions, where failing scans were acquired with less than 120mAs. Acceptable MTF (>1.5 lp/mm for MTF=0.2) was obtained at all but Institution 6 due to the largest scan voxel size (0.35mm). The geometric accuracy passed (<1.5%) at five of the seven institutions. Conclusion: Our QA software can be used to rapidly perform quantitative imaging QA for small animal irradiators, accumulate results over time, and display possible changes in imaging functionality from its original performance and/or from the recommended tolerance levels. This tool will aid researchers in maintaining high image quality, enabling precise conformal dose delivery to small animals.« less

Comparative evaluation of image quality among different detector configurations using area detector computed tomography.

PubMed

Miura, Yohei; Ichikawa, Katsuhiro; Fujimura, Ichiro; Hara, Takanori; Hoshino, Takashi; Niwa, Shinji; Funahashi, Masao

2018-03-01

The 320-detector row computed tomography (CT) system, i.e., the area detector CT (ADCT), can perform helical scanning with detector configurations of 4-, 16-, 32-, 64-, 80-, 100-, and 160-detector rows for routine CT examinations. This phantom study aimed to compare the quality of images obtained using helical scan mode with different detector configurations. The image quality was measured using modulation transfer function (MTF) and noise power spectrum (NPS). The system performance function (SP), based on the pre-whitening theorem, was calculated as MTF 2 /NPS, and compared between configurations. Five detector configurations, i.e., 0.5 × 16 mm (16 row), 0.5 × 64 mm (64 row), 0.5 × 80 mm (80 row), 0.5 × 100 mm (100 row), and 0.5 × 160 mm (160 row), were compared using a constant volume CT dose index (CTDI vol ) of 25 mGy, simulating the scan of an adult abdomen, and with a constant effective mAs value. The MTF was measured using the wire method, and the NPS was measured from images of a 20-cm diameter phantom with uniform content. The SP of 80-row configuration was the best, for the constant CTDI vol , followed by the 64-, 160-, 16-, and 100-row configurations. The decrease in the rate of the 100- and 160-row configurations from the 80-row configuration was approximately 30%. For the constant effective mAs, the SPs of the 100-row and 160-row configurations were significantly lower, compared with the other three detector configurations. The 80- and 64-row configurations were adequate in cases that required dose efficiency rather than scan speed.

Characterization of on-site digital mammography systems: Direct versus indirect conversion detectors

NASA Astrophysics Data System (ADS)

Youn, Hanbean; Han, Jong Chul; Yun, Seungman; Kam, Soohwa; Cho, Seungryong; Kim, Ho Kyung

2015-06-01

We investigated the performances of two digital mammography systems. The systems use a cesium-iodide (CsI) scintillator and an amorphous selenium ( a-Se) photoconductor for X-ray detection and are installed in the same hospital. As physical metrics, we measured the modulationtransfer function (MTF), the noise-power spectrum (NPS), and the detective quantum efficiency (DQE). In addition, we analyzed the contrast-detail performances of the two systems by using a commercial contrast-detail phantom. The CsI-based indirect conversion detector provided better MTF and DQE performances than the a-Se-based direct conversion detector whereas the former provided a poorer NPS performance than the latter. These results are explained by the fact that the CsI-based detector used an MTF restoration preprocessing algorithm. The a-Se-based detector showed better contrast-detail performance than the CsI-based detector. We believe that the highfrequency noise characteristic of a detector is more responsible for the visibility of small details than its spatial-resolution performance.

Suppressing the image smear of the vibration modulation transfer function for remote-sensing optical cameras.

PubMed

Li, Jin; Liu, Zilong; Liu, Si

2017-02-20

In on-board photographing processes of satellite cameras, the platform vibration can generate image motion, distortion, and smear, which seriously affect the image quality and image positioning. In this paper, we create a mathematical model of a vibrating modulate transfer function (VMTF) for a remote-sensing camera. The total MTF of a camera is reduced by the VMTF, which means the image quality is degraded. In order to avoid the degeneration of the total MTF caused by vibrations, we use an Mn-20Cu-5Ni-2Fe (M2052) manganese copper alloy material to fabricate a vibration-isolation mechanism (VIM). The VIM can transform platform vibration energy into irreversible thermal energy with its internal twin crystals structure. Our experiment shows the M2052 manganese copper alloy material is good enough to suppress image motion below 125 Hz, which is the vibration frequency of satellite platforms. The camera optical system has a higher MTF after suppressing the vibration of the M2052 material than before.

Modulation Transfer Function of Infrared Focal Plane Arrays

NASA Technical Reports Server (NTRS)

Gunapala, S. D.; Rafol, S. B.; Ting, D. Z.; Soibel, A.; Hill, C. J.; Khoshakhlagh, A.; Liu, J. K.; Mumolo, J. M.; Hoglund, L.; Luong, E. M.

2015-01-01

Modulation transfer function (MTF) is the ability of an imaging system to faithfully image a given object. The MTF of an imaging system quantifies the ability of the system to resolve or transfer spatial frequencies. In this presentation we will discuss the detail MTF measurements of 1024x1024 pixels mid -wavelength and long- wavelength quantum well infrared photodetector, and 320x256 pixels long- wavelength InAs/GaSb superlattice infrared focal plane arrays (FPAs). Long wavelength Complementary Barrier Infrared Detector (CBIRD) based on InAs/GaSb superlattice material is hybridized to recently designed and fabricated 320x256 pixel format ROIC. The n-type CBIRD was characterized in terms of performance and thermal stability. The experimentally measured NE delta T of the 8.8 micron cutoff n-CBIRD FPA was 18.6 mK with 300 K background and f/2 cold stop at 78K FPA operating temperature. The horizontal and vertical MTFs of this pixel fully delineated CBIRD FPA at Nyquist frequency are 49% and 52%, respectively.

Optical design of optical synthetic aperture telescope

NASA Astrophysics Data System (ADS)

Zhou, Chenghao; Wang, Zhile

2018-03-01

Optical synthetic aperture (OSA) is a promising solution for very high-resolution imaging while reducing its volume and mass. In this paper, first, the configuration of OSA systems are analyzed and the design methods of two types (Fizeau and Michelson) of OSA systems are summarized and researched. Second, Fizeau and Michelson OSA prototype systems are designed in detail. In the Michelson configuration, the instrument is made of sub-telescopes distributed in entrance pupil and combined by a common telescope via phase delay line. The design of Michelson configuration is more difficult than that of Fizeau configuration. In the design of Fizeau configuration, according to the third aberration theory tworeflective system is designed. Then the primary mirror of the two mirror system is replaced by the synthetic aperture. The whole system was simulated by Zemax software to obtain the Modulation transform function (MTF). In the design of Michelson configuration, the system is first divided into three parts: the afocal interferometric telescopes, beam combiner system and phase delay line. The three parts are designed respectively and then combined in Zemax software to obtain the MTF.

Optimization of design and operating parameters of a space-based optical-electronic system with a distributed aperture.

PubMed

Tcherniavski, Iouri; Kahrizi, Mojtaba

2008-11-20

Using a gradient optimization method with objective functions formulated in terms of a signal-to-noise ratio (SNR) calculated at given values of the prescribed spatial ground resolution, optimization problems of geometrical parameters of a distributed optical system and a charge-coupled device of a space-based optical-electronic system are solved for samples of the optical systems consisting of two and three annular subapertures. The modulation transfer function (MTF) of the distributed aperture is expressed in terms of an average MTF taking residual image alignment (IA) and optical path difference (OPD) errors into account. The results show optimal solutions of the optimization problems depending on diverse variable parameters. The information on the magnitudes of the SNR can be used to determine the number of the subapertures and their sizes, while the information on the SNR decrease depending on the IA and OPD errors can be useful in design of a beam combination control system to produce the necessary requirements to its accuracy on the basis of the permissible deterioration in the image quality.

Study of the detail content of Apollo orbital photography

NASA Technical Reports Server (NTRS)

Kinzly, R. E.

1972-01-01

The results achieved during a study of the Detail Content of Apollo Orbital Photography are reported. The effect of residual motion smear or image reproduction processes upon the detail content of lunar surface imagery obtained from the orbiting command module are assessed. Data and conclusions obtained from the Apollo 8, 12, 14 and 15 missions are included. For the Apollo 8, 12 and 14 missions, the bracket-mounted Hasselblad camera had no mechanism internal to the camera for motion compensation. If the motion of the command module were left totally uncompensated, these photographs would exhibit a ground smear varying from 12 to 27 meters depending upon the focal length of the lens and the exposure time. During the photographic sequences motion compensation was attempted by firing the attitude control system of the spacecraft at a rate to compensate for the motion relative to the lunar surface. The residual smear occurring in selected frames of imagery was assessed using edge analyses methods to obtain and achieved modulation transfer function (MTF) which was compared to a baseline MTF.

Evaluation of image quality in terahertz pulsed imaging using test objects.

PubMed

Fitzgerald, A J; Berry, E; Miles, R E; Zinovev, N N; Smith, M A; Chamberlain, J M

2002-11-07

As with other imaging modalities, the performance of terahertz (THz) imaging systems is limited by factors of spatial resolution, contrast and noise. The purpose of this paper is to introduce test objects and image analysis methods to evaluate and compare THz image quality in a quantitative and objective way, so that alternative terahertz imaging system configurations and acquisition techniques can be compared, and the range of image parameters can be assessed. Two test objects were designed and manufactured, one to determine the modulation transfer functions (MTF) and the other to derive image signal to noise ratio (SNR) at a range of contrasts. As expected the higher THz frequencies had larger MTFs, and better spatial resolution as determined by the spatial frequency at which the MTF dropped below the 20% threshold. Image SNR was compared for time domain and frequency domain image parameters and time delay based images consistently demonstrated higher SNR than intensity based parameters such as relative transmittance because the latter are more strongly affected by the sources of noise in the THz system such as laser fluctuations and detector shot noise.

Characterizing 3D sensors using the 3D modulation transfer function

NASA Astrophysics Data System (ADS)

Kellner, Timo; Breitbarth, Andreas; Zhang, Chen; Notni, Gunther

2018-03-01

The fields of optical 3D measurement system applications are continuously expanding and becoming more and more diverse. To evaluate appropriate systems for various measurement tasks, comparable parameters are necessary, whereas the 3D modulation transfer function (3D-MTF) has been established as a further criterion. Its aim is the determination of the system response between the measurement of a straight, sharp-edged cube and its opposite ideal calculated one. Within the scope of this work simulations and practical investigations regarding the 3D-MTF’s influences and its main issues are specifically investigated. Therefore, different determined edge radii representing the high-frequency spectra lead to various decreasing 3D-MTF characteristics. Furthermore, rising sampling frequencies improve its maximum transfer value to a saturation point in dependence of the radius. To approve these results of previous simulations, three fringe projection scanners were selected to determine the diversity. As the best 3D-MTF characteristic, a saturated transfer value of H_3D( f_N, 3D) = 0.79 has been identified at a sufficient sampling frequency, which is reached at four times the Nyquist limit. This high 3D resolution can mainly be achieved due to an improved camera projector interaction. Additionally, too small sampling ratios lead to uncertainties in the edge function determination, while higher ratios do not show major improvements. In conclusion, the 3D-MTF algorithm has thus been practically verified and its repeatability as well as its robustness have been confirmed.

Specific cerebral activation due to visual erotic stimuli in male-to-female transsexuals compared with male and female controls: an fMRI study.

PubMed

Gizewski, Elke R; Krause, Eva; Schlamann, Marc; Happich, Friederike; Ladd, Mark E; Forsting, Michael; Senf, Wolfgang

2009-02-01

Transsexuals harbor the strong feeling of having been born to the wrong sex. There is a continuing controversial discussion of whether or not transsexualism has a biological representation. Differences between males and females in terms of functional imaging during erotic stimuli have been previously described, revealing gender-specific results. Therefore, we postulated that male-to-female (MTF) transsexuals may show specific cerebral activation differing from their biological gender. Cerebral activation patterns during viewing of erotic film excerpts in functional magnetic resonance imaging (fMRI). Twelve male and 12 female heterosexual volunteers and 12 MTF transsexuals before any treatment viewed erotic film excerpts during fMRI. Additionally, subjective rating of sexual arousal was assessed. Statistics were performed using the Statistical Parametric Mapping software. Significantly enhanced activation for men compared with women was revealed in brain areas involved in erotic processing, i.e., the thalamus, the amygdala, and the orbitofrontal and insular cortex, whereas no specific activation for women was found. When comparing MTF transsexuals with male volunteers, activation patterns similar to female volunteers being compared with male volunteers were revealed. Sexual arousal was assessed using standard rating scales and did not differ significantly for the three groups. We revealed a cerebral activation pattern in MTF transsexuals compared with male controls similar to female controls compared with male controls during viewing of erotic stimuli, indicating a tendency of female-like cerebral processing in transsexualism.

Geographic variation within the military health system.

PubMed

Kimsey, Linda; Olaiya, Samuel; Smith, Chad; Hoburg, Andrew; Lipsitz, Stuart R; Koehlmoos, Tracey; Nguyen, Louis L; Weissman, Joel S

2017-04-13

This study seeks to quantify variation in healthcare utilization and per capita costs using system-defined geographic regions based on enrollee residence within the Military Health System (MHS). Data for fiscal years 2007 - 2010 were obtained from the Military Health System under a data sharing agreement with the Defense Health Agency (DHA). DHA manages all aspects of the Department of Defense Military Health System, including TRICARE. Adjusted rates were calculated for per capita costs and for two procedures with high interest to the MHS- back surgery and Cesarean sections for TRICARE Prime and Plus enrollees. Coefficients of variation (CoV) and interquartile ranges (IQR) were calculated and analyzed using residence catchment area as the geographic unit. Catchment areas anchored by a Military Treatment Facility (MTF) were compared to catchment areas not anchored by a MTF. Variation, as measured by CoV, was 0.37 for back surgery and 0.13 for C-sections in FY 2010- comparable to rates documented in other healthcare systems. The 2010 CoV (and average cost) for per capita costs was 0.26 ($3,479.51). Procedure rates were generally lower and CoVs higher in regions anchored by a MTF compared with regions not anchored by a MTF, based on both system-wide comparisons and comparisons of neighboring areas. In spite of its centrally managed system and relatively healthy beneficiaries with very robust health benefits, the MHS is not immune to unexplained variation in utilization and cost of healthcare.

Comparative investigation of the detective quantum efficiency of direct and indirect conversion detector technologies in dedicated breast CT.

PubMed

Kuttig, Jan D; Steiding, Christian; Kolditz, Daniel; Hupfer, Martin; Karolczak, Marek; Kalender, Willi A

2015-06-01

To investigate the dose saving potential of direct-converting CdTe photon-counting detector technology for dedicated breast CT. We analyzed the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE) of two detector technologies, suitable for breast CT (BCT): a flat-panel energy-integrating detector with a 70 μm and a 208 μm thick gadolinium oxysulfide (GOS) and a 150 μm thick cesium iodide (CsI) scintillator and a photon-counting detector with a 1000 μm thick CdTe sensor. The measurements for GOS scintillator thicknesses of 70 μm and 208 μm delivered 10% pre-sampled MTF values of 6.6 mm(-1) and 3.2 mm(-1), and DQE(0) values of 23% and 61%. The 10% pre-sampled MTF value for the 150 μm thick CsI scintillator 6.9 mm(-1), and the DQE(0) value was 49%. The CdTe sensor reached a 10% pre-sampled MTF value of 8.5 mm(-1) and a DQE(0) value of 85%. The photon-counting CdTe detector technology allows for significant dose reduction compared to the energy-integrating scintillation detector technology used in BCT today. Our comparative evaluation indicates that a high potential dose saving may be possible for BCT by using CdTe detectors, without loss of spatial resolution. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Comparison of methods for acceptance and constancy testing in dental cone-beam computed tomography.

PubMed

Steiding, C; Kolditz, D; Kalender, W

2015-04-01

The aim of this work was to implement, validate, and compare two procedures for routine image quality (IQ) assurance in dental cone-beam computed tomography (CBCT): 1. the German standard DIN 6868 - 161 introduced in 2013 and 2. the established standard IEC 61,223 - 3-5 for clinical CT x-ray equipment referenced as "DIN" and "IEC" below. The approximated in-plane modulation transfer function (MTF), the contrast-to-noise indicator (CNI), and the uniformity indicator (UI*) were determined in accordance with DIN. Image noise, the uniformity index (UI), the contrast-to-noise ratio (CNR), and the 3 D MTF were measured according to IEC 61,223 - 3-5 using a previously proposed quality assurance (QA) framework. For this, a modular phantom was used. All experiments were performed on a clinical dental CBCT unit. The severity of image artefacts was measured at different z-positions. A dedicated computer program was implemented to allow for automated QA procedure. The position and orientation of the phantoms were detected automatically in all of the measurements providing a reproducible placement of the evaluation regions and volumes. 50 % and 10 % in-plane MTF values of the approximated and the exact MTF calculation procedure were in agreement to within 5 %. With increasing axial distance from the isocentre, UI* and CNI dropped by 30 % and 19 %, respectively. Conventional IQ parameters showed higher sensitivity to image artefacts; i. e., UI and CNR were reduced by about 197 % and 37 %. The implemented automated QA routines are compatible with both the DIN and the IEC approach and offer reliable and quantitative tracking of imaging performance in dental CBCT for clinical practice. However, there is no equivalence between the DIN and the IEC metrics. In addition, direct measurements of physical IQ parameters such as image contrast and noise, uniformity, and axial resolution are not supported by the new concept according to DIN. The new DIN 6868 - 161 is not equivalent to the established IEC 61 223 - 3-5. Noise, uniformity, and contrast are well-suited to assess image artefacts. The implemented automated quality assurance program fits clinical routine. © Georg Thieme Verlag KG Stuttgart · New York.

Performance measurement of commercial electronic still picture cameras

NASA Astrophysics Data System (ADS)

Hsu, Wei-Feng; Tseng, Shinn-Yih; Chiang, Hwang-Cheng; Cheng, Jui-His; Liu, Yuan-Te

1998-06-01

Commercial electronic still picture cameras need a low-cost, systematic method for evaluating the performance. In this paper, we present a measurement method to evaluating the dynamic range and sensitivity by constructing the opto- electronic conversion function (OECF), the fixed pattern noise by the peak S/N ratio (PSNR) and the image shading function (ISF), and the spatial resolution by the modulation transfer function (MTF). The evaluation results of individual color components and the luminance signal from a PC camera using SONY interlaced CCD array as the image sensor are then presented.

Constraining the surface properties of effective Skyrme interactions

NASA Astrophysics Data System (ADS)

Jodon, R.; Bender, M.; Bennaceur, K.; Meyer, J.

2016-08-01

Background: Deformation energy surfaces map how the total binding energy of a nuclear system depends on the geometrical properties of intrinsic configurations, thereby providing a powerful tool to interpret nuclear spectroscopy and large-amplitude collective-motion phenomena such as fission. The global behavior of the deformation energy is known to be directly connected to the surface properties of the effective interaction used for its calculation. Purpose: The precise control of surface properties during the parameter adjustment of an effective interaction is key to obtain a reliable and predictive description of nuclear properties. The most relevant indicator is the surface-energy coefficient asurf. There are several possibilities for its definition and estimation, which are not fully equivalent and require a computational effort that can differ by orders of magnitude. The purpose of this study is threefold: first, to identify a scheme for the determination of asurf that offers the best compromise between robustness, precision, and numerical efficiency; second, to analyze the correlation between values for asurf and the characteristic energies of the fission barrier of 240Pu; and third, to lay out an efficient and robust procedure for how the deformation properties of the Skyrme energy density functional (EDF) can be constrained during the parameter fit. Methods: There are several frequently used possibilities to define and calculate the surface energy coefficient asurf of effective interactions built for the purpose of self-consistent mean-field calculations. The most direct access is provided by the model system of semi-infinite nuclear matter, but asurf can also be extracted from the systematics of binding energies of finite nuclei. Calculations can be carried out either self-consistently [Hartree-Fock (HF)], which incorporates quantal shell effects, or in one of the semiclassical extended Thomas-Fermi (ETF) or modified Thomas-Fermi (MTF) approximations. The latter is of particular interest because it provides asurf as a numerical integral without the need to solve self-consistent equations. Results for semi-infinite nuclear matter obtained with the HF, ETF, and MTF methods will be compared with one another and with asurf, as deduced from ETF calculations of very heavy fictitious nuclei. Results: The surface energy coefficient of 76 parametrizations of the Skyrme EDF have been calculated. Values obtained with the HF, ETF, and MTF methods are not identical, but differ by fairly constant systematic offsets. By contrast, extracting asurf from the binding energy of semi-infinite matter or of very large nuclei within the same method gives the same result within the numerical uncertainties. Conclusions: Despite having some drawbacks compared to the other methods studied here, the MTF approach provides sufficiently precise values for asurf such that it can be used as a very robust constraint on surface properties during a parameter fit at negligible additional cost. While the excitation energy of superdeformed states and the height of fission barriers is obviously strongly correlated to asurf, the presence of shell effects prevents a one-to-one correspondence between them. As in addition the value of asurf providing realistic fission barriers depends on the choices made for corrections for spurious motion, its "best value" (within a given scheme to calculate it) depends on the fit protocol. Through the construction of a series of eight parametrizations SLy5s1-SLy5s8 of the standard Skyrme EDF with systematically varied asurf value, it is shown how to arrive at a fit with realistic deformation properties.

Emulation Aid System II (EASY II) System Programmer’s Guide.

DTIC Science & Technology

1981-03-01

DISK-SAVE, PASSWD =SSSS .MTUINIT= 17 ,MTF IILE=99,D)SKUNIT=7. RESTORE-DISK, PASSWD =SSSS,,MTt!NI=I 7,MTF [LE--=99,DSKtJNIT=7. where PASSWD - a system disk...DISK-SAVE, PASSWD =SSSS ,MTUNIT=17,MTFILE=99,DSKtJNIT=7. SAVE A DISK FILE ON TAPE HELP ,O,O,O. DSKSV. EDIT. CR’r BASED EDITOR (COMM ANDS EXPLAINED AS...BE EXPLICITLY TURNED ON QCNTRL ,LOCKED. RDTAPE,UNIT= 17. READING TAPE FOR USE WITH 6000 AND PRINT. 0. RDTAPE. RESTORE-DISK, PASSWD =SSSS ,MTUNIT= 17

Design Method For Ultra-High Resolution Linear CCD Imagers

NASA Astrophysics Data System (ADS)

Sheu, Larry S.; Truong, Thanh; Yuzuki, Larry; Elhatem, Abdul; Kadekodi, Narayan

1984-11-01

This paper presents the design method to achieve ultra-high resolution linear imagers. This method utilizes advanced design rules and novel staggered bilinear photo sensor arrays with quadrilinear shift registers. Design constraint in the detector arrays and shift registers are analyzed. Imager architecture to achieve ultra-high resolution is presented. The characteristics of MTF, aliasing, speed, transfer efficiency and fine photolithography requirements associated with this architecture are also discussed. A CCD imager with advanced 1.5 um minimum feature size was fabricated. It is intended as a test vehicle for the next generation small sampling pitch ultra-high resolution CCD imager. Standard double-poly, two-phase shift registers were fabricated at an 8 um pitch using the advanced design rules. A special process step that blocked the source-drain implant from the shift register area was invented. This guaranteed excellent performance of the shift registers regardless of the small poly overlaps. A charge transfer efficiency of better than 0.99995 and maximum transfer speed of 8 MHz were achieved. The imager showed excellent performance. The dark current was less than 0.2 mV/ms, saturation 250 mV, adjacent photoresponse non-uniformity ± 4% and responsivity 0.7 V/ μJ/cm2 for the 8 μm x 6 μm photosensor size. The MTF was 0.6 at 62.5 cycles/mm. These results confirm the feasibility of the next generation ultra-high resolution CCD imagers.

Effective DQE (eDQE) for monoscopic and stereoscopic chest radiography imaging systems with the incorporation of anatomical noise

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

Boyce, Sarah J.; Choudhury, Kingshuk Roy; Samei, Ehsan

2013-09-15

Purpose: Stereoscopic chest biplane correlation imaging (stereo/BCI) has been proposed as an alternative modality to single view chest x-ray (CXR). The metrics effective modulation transfer function (eMTF), effective normalized noise power spectrum (eNNPS), and effective detective quantum efficiency (eDQE) have been proposed as clinically relevant metrics for assessing clinical system performance taking into consideration the magnification and scatter effects. This study compared the metrics eMTF, eNNPS, eDQE, and detectability index for stereo/BCI and single view CXR under isodose conditions at two magnifications for two anthropomorphic phantoms of differing sizes.Methods: Measurements for the eMTF were taken for two phantom sizes withmore » an opaque edge test device using established techniques. The eNNPS was measured at two isodose conditions for two phantoms using established techniques. The scatter was measured for two phantoms using an established beam stop method. All measurements were also taken at two different magnifications with two phantoms. A geometrical phantom was used for comparison with prior results for CXR although the results for an anatomy free phantom are not expected to vary for BCI.Results: Stereo/BCI resulted in improved metrics compared to single view CXR. Results indicated that magnification can potentially improve the detection performance primarily due to the air gap which reduced scatter by ∼20%. For both phantoms, at isodose, eDQE(0) for stereo/BCI was ∼100 times higher than that for CXR. Magnification at isodose improved eDQE(0) by ∼10 times for stereo/BCI. Increasing the dose did not improve eDQE. The detectability index for stereo/BCI was ∼100 times better than single view CXR for all conditions. The detectability index was also not improved with increased dose.Conclusions: The findings indicate that stereo/BCI with magnification may improve detectability of subtle lung nodules compared to single view CXR. Results were improved with magnification for the smaller phantom but not for the larger phantom. The effective DQE and the detectability index did not improve with increasing dose.« less

Gender identity rather than sexual orientation impacts on facial preferences.

PubMed

Ciocca, Giacomo; Limoncin, Erika; Cellerino, Alessandro; Fisher, Alessandra D; Gravina, Giovanni Luca; Carosa, Eleonora; Mollaioli, Daniele; Valenzano, Dario R; Mennucci, Andrea; Bandini, Elisa; Di Stasi, Savino M; Maggi, Mario; Lenzi, Andrea; Jannini, Emmanuele A

2014-10-01

Differences in facial preferences between heterosexual men and women are well documented. It is still a matter of debate, however, how variations in sexual identity/sexual orientation may modify the facial preferences. This study aims to investigate the facial preferences of male-to-female (MtF) individuals with gender dysphoria (GD) and the influence of short-term/long-term relationships on facial preference, in comparison with healthy subjects. Eighteen untreated MtF subjects, 30 heterosexual males, 64 heterosexual females, and 42 homosexual males from university students/staff, at gay events, and in Gender Clinics were shown a composite male or female face. The sexual dimorphism of these pictures was stressed or reduced in a continuous fashion through an open-source morphing program with a sequence of 21 pictures of the same face warped from a feminized to a masculinized shape. An open-source morphing program (gtkmorph) based on the X-Morph algorithm. MtF GD subjects and heterosexual females showed the same pattern of preferences: a clear preference for less dimorphic (more feminized) faces for both short- and long-term relationships. Conversely, both heterosexual and homosexual men selected significantly much more dimorphic faces, showing a preference for hyperfeminized and hypermasculinized faces, respectively. These data show that the facial preferences of MtF GD individuals mirror those of the sex congruent with their gender identity. Conversely, heterosexual males trace the facial preferences of homosexual men, indicating that changes in sexual orientation do not substantially affect preference for the most attractive faces. © 2014 International Society for Sexual Medicine.

In vitro comparative optical bench analysis of a spherical and aspheric optic design of the same IOL model.

PubMed

Tandogan, Tamer; Auffarth, Gerd U; Choi, Chul Y; Liebing, Stephanie; Mayer, Christian; Khoramnia, Ramin

2017-02-08

To analyse objective optical properties of the spherical and aspheric design of the same intraocular lens (IOL) model using optical bench analysis. This study entailed a comparative analysis of 10 spherical C-flex 570 C and 10 aspheric C-flex 970 C IOLs (Rayner Intraocular Lenses Ltd., Hove, UK) of 26 diopters [D] using an optical bench (OptiSpheric, Trioptics, Germany). In all lenses, we evaluated the modulation transfer function (MTF) at 50 lp/mm and 100 lp/mm and the Strehl Ratio using a 3-mm (photopic) and 4.5-mm (mesopic) aperture. At 50 lp/mm, the MTF values were 0.713/0.805 (C-flex 570 C/C-flex 970 C) for a 3-mm aperture and 0.294/0.591 for a 4.5-mm aperture. At 100 lp/mm, the MTF values were 0.524/0.634 for a 3-mm aperture and 0.198/0.344 for a 4.5-mm aperture. The Strehl Ratio was 0.806/0.925 and 0.237/0.479 for a 3-mm and 4.5-mm aperture respectively. A Mann-Whitney U test revealed all intergroup differences to be statistically significant (p < 0.01). The aspheric IOL design achieved higher MTF values than the spherical design of the same IOL for both apertures. Moreover, the differences between the two designs of the IOL were more prominent for larger apertures. This suggests that the evaluated IOL provides enhanced optical quality to patients with larger pupils or working under mesopic conditions.

Clinical and theoretical parallels between desire for limb amputation and gender identity disorder.

PubMed

Lawrence, Anne A

2006-06-01

Desire for amputation of a healthy limb has usually been regarded as a paraphilia (apotemnophilia), but some researchers propose that it may be a disorder of identity, similar to Gender Identity Disorder (GID) or transsexualism. Similarities between the desire for limb amputation and nonhomosexual male-to-female (MtF) transsexualism include profound dissatisfaction with embodiment, related paraphilias from which the conditions plausibly derive (apotemnophilia and autogynephilia), sexual arousal from simulation of the sought-after status (pretending to be an amputee and transvestism), attraction to persons with the same body type one wants to acquire, and an elevated prevalence of other paraphilic interests. K. Freund and R. Blanchard (1993) proposed that nonhomosexual MtF transsexualism represents an erotic target location error, in which men whose preferred erotic targets are women also eroticize their own feminized bodies. Desire for limb amputation may also reflect an erotic target location error, occurring in combination with an unusual erotic target preference for amputees. This model predicts that persons who desire limb amputation would almost always be attracted to amputees and would display an increased prevalence of gender identity problems, both of which have been observed. Persons who desire limb amputation and nonhomosexual MtF transsexuals often assert that their motives for wanting to change their bodies reflect issues of identity rather than sexuality, but because erotic/romantic orientations contribute significantly to identity, such distinctions may not be meaningful. Experience with nonhomosexual MtF transsexualism suggests possible directions for research and treatment for persons who desire limb amputation.

Evaluation of loss in optical quality of multifocal intraocular lenses with glistenings.

PubMed

DeHoog, Edward; Doraiswamy, Anand

2016-04-01

To study the impact of loss in optical quality from glistenings in diffractive multifocal intraocular lenses (IOLs) using ray tracing in a model eye. Independent research laboratory, Irvine, California, USA. Experimental study. A pseudophakic eye model was constructed in Zemax, an optical ray-tracing program, using the Arizona eye model as the basis. The Mie scattering theory was used to describe the intensity and direction of light as it scattered for a spherical particle immersed in a diffractive multifocal IOL. To evaluate the impact of glistening scatter, a more advanced eye model was constructed in Fred, a nonsequential optical ray-tracing software. An evaluation of scatter and modulation transfer function (MTF) was performed for a hydrophobic biomaterial with a refractive index of 1.54 for various sizes and densities of glistenings under mesopic conditions. As predicted by the Mie theory, the amount of scatter was a function of the change in the refractive index, size of the scatterer, and volume fraction of the scatterers. This modeling showed that an increase in density of glistenings can lead to a significant drop of MTF of the IOL. This effect was more pronounced in multifocal IOLs than in monofocal IOLs. Mathematical modeling showed that glistenings in multifocal IOLs lead to a reduction in MTF of the IOL and the pseudophakic eye. The relative loss of MTF in multifocal IOLs was more significant than in monofocal IOLs because of the nature of the design. Drs. DeHoog and Doraiswamy are consultants to Advanced Vision Science, Inc. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Evaluation of the impact of light scatter from glistenings in pseudophakic eyes.

PubMed

DeHoog, Edward; Doraiswamy, Anand

2014-01-01

To study the impact of light scatter from glistenings in pseudophakic eyes using ray tracing in a model eye Department of Research, Advanced Vision Science, Inc., Goleta, California, USA. Mathematical modeling and simulation. A pseudophakic eye model was constructed in Zemax using the Arizona eye model as the basis. The Mie scattering theory was used to describe the intensity and direction of light as it scatters for a spherical particle immersed in a given media (intraocular lens [IOL]). The modeling and evaluation of scatter and modulation transfer function (MTF) were performed for several biomaterials with various size and density of glistenings under scotopic, mesopic, and photopic conditions. As predicted by the Mie theory, the amount of scatter was a function of the relative difference in refractive index between the media and the scatterer, the size of the scatterer, and the volume fraction of the scatterer. The simulation demonstrated that an increase in density of glistenings can lead to a significant drop in the MTF of the IOL and the pseudophakic eye. This effect was more pronounced in IOLs with smaller cavitations, and the observation was consistent for all tested biomaterials. Mathematical modeling demonstrated that glistenings in IOLs will lead to reduction in the MTF of the IOL and the pseudophakic eye. The loss in MTF was more pronounced at high densities and small cavitation sizes across all biomaterials. Inconsistent and poor clinical quantification of glistenings in IOLs may explain some inconsistencies in the literature. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Gender transition affects neural correlates of empathy: A resting state functional connectivity study with ultra high-field 7T MR imaging.

PubMed

Spies, M; Hahn, A; Kranz, G S; Sladky, R; Kaufmann, U; Hummer, A; Ganger, S; Kraus, C; Winkler, D; Seiger, R; Comasco, E; Windischberger, C; Kasper, S; Lanzenberger, R

2016-09-01

Sex-steroid hormones have repeatedly been shown to influence empathy, which is in turn reflected in resting state functional connectivity (rsFC). Cross-sex hormone treatment in transgender individuals provides the opportunity to examine changes to rsFC over gender transition. We aimed to investigate whether sex-steroid hormones influence rsFC patterns related to unique aspects of empathy, namely emotion recognition and description as well as emotional contagion. RsFC data was acquired with 7Tesla magnetic resonance imaging in 24 male-to-female (MtF) and 33 female-to-male (FtM) transgender individuals before treatment, in addition to 33 male- and 44 female controls. Of the transgender participants, 15 MtF and 20 FtM were additionally assessed after 4 weeks and 4 months of treatment. Empathy scores were acquired at the same time-points. MtF differed at baseline from all other groups and assimilated over the course of gender transition in a rsFC network around the supramarginal gyrus, a region central to interpersonal emotion processing. While changes to sex-steroid hormones did not correlate with rsFC in this network, a sex hormone independent association between empathy scores and rsFC was found. Our results underline that 1) MtF transgender persons demonstrate unique rsFC patterns in a network related to empathy and 2) changes within this network over gender transition are likely related to changes in emotion recognition, -description, and -contagion, and are sex-steroid hormone independent. Copyright © 2016 Elsevier Inc. All rights reserved.

Finger length ratio (2D:4D) in adults with gender identity disorder.

PubMed

Kraemer, Bernd; Noll, Thomas; Delsignore, Aba; Milos, Gabriella; Schnyder, Ulrich; Hepp, Urs

2009-06-01

From early childhood, gender identity and the 2nd to 4th finger length ratio (2D:4D) are discriminative characteristics between sexes. Both the human brain and 2D:4D may be influenced by prenatal testosterone levels. This calls for an examination of 2D:4D in patients with gender identity disorder (GID) to study the possible influence of prenatal testosterone on gender identity. Until now, the only study carried out on this issue suggests lower prenatal testosterone levels in right-handed male-to-female GID patients (MtF). We compared 2D:4D of 56 GID patients (39 MtF; 17 female-to-male GID patients, FtM) with data from a control sample of 176 men and 190 women. Bivariate group comparisons showed that right hand 2D:4D in MtF was significantly higher (feminized) than in male controls, but similar to female controls. The comparison of 2D:4D ratios of biological women revealed significantly higher (feminized) values for right hands of right handed FtM. Analysis of variance confirmed significant effects for sex and for gender identity on 2D:4D ratios but not for sexual orientation or for the interaction among variables. Our results indirectly point to the possibility of a weak influence of reduced prenatal testosterone as an etiological factor in the multifactorially influenced development of MtF GID. The development of FtM GID seems even more unlikely to be notably influenced by prenatal testosterone.

The EarthCARE multi spectral imager thermal infrared optical unit

NASA Astrophysics Data System (ADS)

Chang, M. P. J. L.; Woods, D.; Baister, Guy; Lobb, Dan; Wood, Trevor

2017-11-01

The EarthCARE satellite mission objective is the observation of clouds and aerosols from low Earth orbit. The key spatial context providing instrument within the payload suite of 4 instruments is the Multi-Spectral Imager (MSI), previously described in [1]. The MSI is intended to provide information on the horizontal variability of the atmospheric conditions and to identify e.g. cloud type, textures, and temperature. It will form Earth images at 500m ground sample distance (GSD) over a swath width of 150km; it will image Earth in 7 spectral bands: one visible, one near-IR, two short-wave IR and three thermal IR. The instrument will be comprised of two key parts: • a visible-NIR-SWIR (VNS) optical unit radiometrically calibrated using a sun illuminated quasivolume diffuser and shutter system • a thermal IR (TIR) optical unit radiometrically calibrated using cold space and an internal black-body. This paper, being the first of a sequence of two, will provide an overview of the MSI and enter into more detail the critical performance parameters and detailed design the MSI TIR optical design. The TIR concept is to provide pushbroom imaging of its 3 bands through spectral separation from a common aperture. The result is an efficient, well controlled optical design without the need for multiple focal plane arrays. The designed focal plane houses an area array detector and will meet a challenging set of requirements, including radiometric resolution, accuracy, distortion and MTF.

Intonation and gender perception: applications for transgender speakers.

PubMed

Hancock, Adrienne; Colton, Lindsey; Douglas, Fiacre

2014-03-01

Intonation is commonly addressed in voice and communication feminization therapy, yet empirical evidence of gender differences for intonation is scarce and rarely do studies examine how it relates to gender perception of transgender speakers. This study examined intonation of 12 males, 12 females, six female-to-male, and 14 male-to-female transgender speakers describing a Norman Rockwell image. Several intonation measures were compared between biological gender groups, between perceived gender groups, and between male-to-female (MTF) speakers who were perceived as male, female, or ambiguous gender. Speakers with a larger percentage of utterances with upward intonation and a larger utterance semitone range were perceived as female by listeners, despite no significant differences between the actual intonation of the four gender groups. MTF speakers who do not pass as female appear to use less upward and more downward intonations than female and passing MTF speakers. Intonation has potential for use in transgender communication therapy because it can influence perception to some degree. Copyright © 2014 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

Social context of HIV risk behaviours among male-to-female transgenders of colour.

PubMed

Nemoto, T; Operario, D; Keatley, J; Villegas, D

2004-08-01

To explore the social context of drug use and sexual behaviours that put male-to-female (MTF) transgenders at risk for HIV, focus groups were conducted consisting of African American, Latina and Asian and Pacific Islander MTF transgenders (N = 48) who reside or work in San Francisco, California. Participants were likely to report having unprotected sex with primary partners to signify love and emotional connection, as well as to receive gender validation from their partners. In contrast, viewing sex work with customers as a business encouraged intentious to use condoms. Safer sex intentions with customers were frequently undermined by urgent financial needs, which stemmed from transphobia, employment discrimination and costly procedures associated with gender transition. Participants reported using drugs as a way to cope with or escape life stresses associated with relationships, sex work, transphobia and financial hardship. Interventions with at-risk MTF transgenders should address the interpersonal and social context of unsafe sex and drug use, particularly the unique roles of relationship issues with male partners, stigma, discrimination and community norms regarding sex work and drug use.

Automated Data Handling And Instrument Control Using Low-Cost Desktop Computers And An IEEE 488 Compatible Version Of The ODETA V.

NASA Astrophysics Data System (ADS)

van Leunen, J. A. J.; Dreessen, J.

1984-05-01

The result of a measurement of the modulation transfer function is only useful as long as it is accompanied by a complete description of all relevant measuring conditions involved. For this reason it is necessary to file a full description of the relevant measuring conditions together with the results. In earlier times some of our results were rendered useless because some of the relevant measuring conditions were accidentally not written down and were forgotten. This was mainly due to the lack of concensus about which measuring conditions had to be filed together with the result of a measurement. One way to secure uniform and complete archiving of measuring conditions and results is to automate the data handling. An attendent advantage of automation of data handling is that it does away with the time-consuming correction of rough measuring results. The automation of the data handling was accomplished with rather cheap desktop computers, which were powerfull enough, however, to allow us to automate the measurement as well. After automation of the data handling we started with automatic collection of rough measurement data. Step by step we extended the automation by letting the desktop computer control more and more of the measuring set-up. At present the desktop computer controls all the electrical and most of the mechanical measuring conditions. Further it controls and reads the MTF measuring instrument. Focussing and orientation optimization can be fully automatic, semi-automatic or completely manual. MTF measuring results can be collected automatically but they can also be typed in by hand. Due to the automation we are able to implement proper archival of measuring results together with all necessary measuring conditions. The improved measuring efficiency made it possible to increase the number of routine measurements done in the same time period by an order of magnitude. To our surprise the measuring accuracy also improved by a factor of two. This was due to the much better reproducibility of the automatic optimization, which resulted in better reproducibility of the measurement result. Another advantage of the automation is that the programs that control the data handling and the automatic measurement are "user friendly". They guide the operator through the measuring procedure using information from earlier measurements of equivalent test specimens. This makes it possible to let routine measurements be done by much less skilled assistants. It also removes much of the tedious routine labour normally involved in MTF measurements. It can be concluded that automation of MTF measurements as described in the foregoing enhances the usefulness of MTF results as well as reducing the cost of MTF measurements.

Optical photon transport in powdered-phosphor scintillators. Part II. Calculation of single-scattering transport parameters

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

Poludniowski, Gavin G.; Evans, Philip M.

2013-04-15

Purpose: Monte Carlo methods based on the Boltzmann transport equation (BTE) have previously been used to model light transport in powdered-phosphor scintillator screens. Physically motivated guesses or, alternatively, the complexities of Mie theory have been used by some authors to provide the necessary inputs of transport parameters. The purpose of Part II of this work is to: (i) validate predictions of modulation transform function (MTF) using the BTE and calculated values of transport parameters, against experimental data published for two Gd{sub 2}O{sub 2}S:Tb screens; (ii) investigate the impact of size-distribution and emission spectrum on Mie predictions of transport parameters; (iii)more » suggest simpler and novel geometrical optics-based models for these parameters and compare to the predictions of Mie theory. A computer code package called phsphr is made available that allows the MTF predictions for the screens modeled to be reproduced and novel screens to be simulated. Methods: The transport parameters of interest are the scattering efficiency (Q{sub sct}), absorption efficiency (Q{sub abs}), and the scatter anisotropy (g). Calculations of these parameters are made using the analytic method of Mie theory, for spherical grains of radii 0.1-5.0 {mu}m. The sensitivity of the transport parameters to emission wavelength is investigated using an emission spectrum representative of that of Gd{sub 2}O{sub 2}S:Tb. The impact of a grain-size distribution in the screen on the parameters is investigated using a Gaussian size-distribution ({sigma}= 1%, 5%, or 10% of mean radius). Two simple and novel alternative models to Mie theory are suggested: a geometrical optics and diffraction model (GODM) and an extension of this (GODM+). Comparisons to measured MTF are made for two commercial screens: Lanex Fast Back and Lanex Fast Front (Eastman Kodak Company, Inc.). Results: The Mie theory predictions of transport parameters were shown to be highly sensitive to both grain size and emission wavelength. For a phosphor screen structure with a distribution in grain sizes and a spectrum of emission, only the average trend of Mie theory is likely to be important. This average behavior is well predicted by the more sophisticated of the geometrical optics models (GODM+) and in approximate agreement for the simplest (GODM). The root-mean-square differences obtained between predicted MTF and experimental measurements, using all three models (GODM, GODM+, Mie), were within 0.03 for both Lanex screens in all cases. This is excellent agreement in view of the uncertainties in screen composition and optical properties. Conclusions: If Mie theory is used for calculating transport parameters for light scattering and absorption in powdered-phosphor screens, care should be taken to average out the fine-structure in the parameter predictions. However, for visible emission wavelengths ({lambda} < 1.0 {mu}m) and grain radii (a > 0.5 {mu}m), geometrical optics models for transport parameters are an alternative to Mie theory. These geometrical optics models are simpler and lead to no substantial loss in accuracy.« less

Descriptive Study of Gender Dysphoria in Japanese Individuals with Male-to-Female Gender Identity Disorder.

PubMed

Shinohara, Yoshie; Nakatsuka, Mikiya

2018-04-01

We focus on Japanese individuals with gender identity disorder (GID), especially male-to-female (MTF) GID, who have experienced difficulty in adapting to social life. We clarify what gender dysphoria is, and we examine methods of intervention. Semi-structured interviews were conducted with 11 individuals with MTF-GID from August 2015 to April 2017. We categorized the subjects'experiences regarding dysphoria into the 'Onset of gender dysphoria,' 'Experience of feeling gender dysphoria,' and 'Changes due to receiving medical care.' The subjects reported experiencing great pain and distress because they did not fully understand that they were experiencing dysphoria and could not align their gender identity and their self-identity. All subjects described their experiences of dysphoria as negative. Additionally, all said that the dysphoria was alleviated by a medical intervention such as visiting a gender clinic, receiving a diagnosis and treatment, and changing their physical sex to the sex congruent with their gender identity. The provision of information at the gender clinic and the physical changes achieved by medical intervention exerted a positive effect both mentally and socially on the subjects, who suffered various physical, mental and social problems.

Comparison of interpolation functions to improve a rebinning-free CT-reconstruction algorithm.

PubMed

de las Heras, Hugo; Tischenko, Oleg; Xu, Yuan; Hoeschen, Christoph

2008-01-01

The robust algorithm OPED for the reconstruction of images from Radon data has been recently developed. This reconstructs an image from parallel data within a special scanning geometry that does not need rebinning but only a simple re-ordering, so that the acquired fan data can be used directly for the reconstruction. However, if the number of rays per fan view is increased, there appear empty cells in the sinogram. These cells need to be filled by interpolation before the reconstruction can be carried out. The present paper analyzes linear interpolation, cubic splines and parametric (or "damped") splines for the interpolation task. The reconstruction accuracy in the resulting images was measured by the Normalized Mean Square Error (NMSE), the Hilbert Angle, and the Mean Relative Error. The spatial resolution was measured by the Modulation Transfer Function (MTF). Cubic splines were confirmed to be the most recommendable method. The reconstructed images resulting from cubic spline interpolation show a significantly lower NMSE than the ones from linear interpolation and have the largest MTF for all frequencies. Parametric splines proved to be advantageous only for small sinograms (below 50 fan views).

Assessment of image quality in x-ray radiography imaging using a small plasma focus device

NASA Astrophysics Data System (ADS)

Kanani, A.; Shirani, B.; Jabbari, I.; Mokhtari, J.

2014-08-01

This paper offers a comprehensive investigation of image quality parameters for a small plasma focus as a pulsed hard x-ray source for radiography applications. A set of images were captured from some metal objects and electronic circuits using a low energy plasma focus at different voltages of capacitor bank and different pressures of argon gas. The x-ray source focal spot of this device was obtained to be about 0.6 mm using the penumbra imaging method. The image quality was studied by several parameters such as image contrast, line spread function (LSF) and modulation transfer function (MTF). Results showed that the contrast changes by variations in gas pressure. The best contrast was obtained at a pressure of 0.5 mbar and 3.75 kJ stored energy. The results of x-ray dose from the device showed that about 0.6 mGy is sufficient to obtain acceptable images on the film. The measurements of LSF and MTF parameters were carried out by means of a thin stainless steel wire 0.8 mm in diameter and the cut-off frequency was obtained to be about 1.5 cycles/mm.

A method to optimize the processing algorithm of a computed radiography system for chest radiography.

PubMed

Moore, C S; Liney, G P; Beavis, A W; Saunderson, J R

2007-09-01

A test methodology using an anthropomorphic-equivalent chest phantom is described for the optimization of the Agfa computed radiography "MUSICA" processing algorithm for chest radiography. The contrast-to-noise ratio (CNR) in the lung, heart and diaphragm regions of the phantom, and the "system modulation transfer function" (sMTF) in the lung region, were measured using test tools embedded in the phantom. Using these parameters the MUSICA processing algorithm was optimized with respect to low-contrast detectability and spatial resolution. Two optimum "MUSICA parameter sets" were derived respectively for maximizing the CNR and sMTF in each region of the phantom. Further work is required to find the relative importance of low-contrast detectability and spatial resolution in chest images, from which the definitive optimum MUSICA parameter set can then be derived. Prior to this further work, a compromised optimum MUSICA parameter set was applied to a range of clinical images. A group of experienced image evaluators scored these images alongside images produced from the same radiographs using the MUSICA parameter set in clinical use at the time. The compromised optimum MUSICA parameter set was shown to produce measurably better images.

Design, assembly, and optical bench testing of a high-numerical-aperture miniature injection-molded objective for fiber-optic confocal reflectance microscopy.

PubMed

Chidley, Matthew D; Carlson, Kristen D; Richards-Kortum, Rebecca R; Descour, Michael R

2006-04-10

The design, analysis, assembly methods, and optical-bench test results for a miniature injection-molded plastic objective lens used in a fiber-optic confocal reflectance microscope are presented. The five-lens plastic objective was tested as a stand-alone optical system before its integration into a confocal microscope for in vivo imaging of cells and tissue. Changing the spacing and rotation of the individual optical elements can compensate for fabrication inaccuracies and improve performance. The system performance of the miniature objective lens is measured by use of an industry-accepted slanted-edge modulation transfer function (MTF) metric. An estimated Strehl ratio of 0.61 and a MTF value of 0.66 at the fiber-optic bundle Nyquist frequency have been obtained. The optical bench testing system is configured to permit interactive optical alignment during testing to optimize performance. These results are part of an effort to demonstrate the manufacturability of low-cost, high-performance biomedical optics for high-resolution in vivo imaging. Disposable endoscopic microscope objectives could help in vivo confocal microscopy technology mature to permit wide-scale clinical screening and detection of early cancers and precancerous lesions.

A new clinical unit for digital radiography based on a thick amorphous selenium plate: physical and psychophysical characterization.

PubMed

Rivetti, Stefano; Lanconelli, Nico; Bertolini, Marco; Acchiappati, Domenico

2011-08-01

Here, we present a physical and psychophysical characterization of a new clinical unit (named AcSelerate) for digital radiography based on a thick a-Se layer. We also compared images acquired with and without a software filter (named CRF) developed for reducing sharpness and noise of the images and making them similar to images coming from traditional computed radiography systems. The characterization was achieved in terms of physical figures of merit [modulation transfer function (MTF), noise power spectra (NPS), detective quantum efficiency (DQE)], and psychophysical parameters (contrast-detail analysis with an automatic reading of CDRAD images). We accomplished measurements with four standard beam conditions: RAQ3, RQA5, RQA7, and RQA9. The system shows an excellent MTF (about 50% at the Nyquist frequency). The DQE is about 55% at 0.5 lp/mm and above 20% at the Nyquist frequency and is almost independent from exposure. The contrast-detail curves are comparable to some of the best published data for other systems devoted to imaging in general radiography. The CRF filter influences both the MTF and NPS, but it does lead to very small changes on DQE. Also the visibility of CDRAD details is basically unaltered, when the filter is activated. As normally happens with detector based on direct conversion, the system presents an excellent MTF. The improved efficiency caused by the thick layer allows getting good noise characteristics and DQE results better (about 10% on average) than many of the computed radiography (CR) systems and comparable to those obtained by the best systems for digital radiography available on the market.

Final Report: Radiation-magnetohydrodynamic evolution and instability of conductors driven by megagauss magnetic fields

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

Bauer, Bruno, S.; Siemon, Richard, E.

2008-10-22

We are pleased to report important progress in experimentally characterizing and numerically modeling the transformation into plasma of walls subjected to pulsed megagauss magnetic fields. Understanding this is important to Magnetized Target Fusion (MTF) because an important limitation to the metal liner approach to MTF comes from the strong eddy current heating on the surface of the metal liner. This has intriguing non-linear aspects when the magnetic field is in the megagauss regime as needed for MTF, and may limit the magnetic field in an MTF implosion. Many faculty, students, and staff have contributed to this work, and, implicitly ormore » explicitly, to this report. Contributors include, in addition to the PIs, Andrey Esaulov, Stephan Fuelling, Irvin Lindemuth, Volodymyr Makhin, Ioana Paraschiv, Milena Angelova, Tom Awe, Tasha Goodrich, Arunkumar Prasadam, Andrew Oxner, Bruno Le Galloudec, Radu Presura, and Vladimir Ivanov. Highlights of the progress made during the grant include: • 12 articles published, and 44 conference and workshop presentations made, on a broad range of issues related to this project; • An ongoing experiment that uses the 1 MA, 100-ns Zebra z-pinch at UNR to apply 2 5 megagauss to a variety of metal surfaces, examining plasma formation and evolution; • Numerical simulation studies of the 1-MA Zebra, and potential Shiva Star and Atlas experiments that include realistic equations of state and radiation effects, using a variety of tables. • Collaboration with other groups doing simulations of this experiment at LANL, VNIIEF, SNL, and NumerEx leading to a successful international workshop at UNR in the spring of 2008.« less

[Nutrition and attention deficit hyperactivity disorder: developmental follow-up of the anthropometric variables of a group of patients receiving treatment with osmotic controlled-release methylphenidate].

PubMed

Dura-Trave, T; Yoldi-Petri, M E; Zardoya-Santos, P

2011-09-01

To perform a developmental analysis of the anthropometric variables of a group of patients diagnosed with attention deficit hyperactivity disorder (ADHD) in order to determine the repercussions of treatment with osmotic controlled-release methylphenidate (MTF-OROS). The medical records of 187 patients with ADHD under treatment with MTF-OROS over a period of 30 months were reviewed. Data collected included weight, height and body mass index at diagnosis (baseline) and at 6, 12, 18, 24 and 30 months' follow-up. The mean age at diagnosis was 8.14 ± 1.6 years. The dose of MTF-OROS was progressively increased until 36.9 ± 12.1 mg/day (1.05 mg/kg/day) at day 30 of the follow-up. At diagnosis, 34.9% of patients had a deficient nutritional situation (subnutrition or malnutrition), which affected 50.3% of the patients at 30 months. The baseline value for weight (Z-score) progressively decreased during treatment until values that were significantly lower than the baseline value at 12 months were reached (p < 0.05); these values remained significantly lower until 30 months. The baseline value for height (Z-score) also progressively decreased during treatment until values that were significantly lower than the baseline value at 24 and 30 months were reached (p < 0.05). At the time they were diagnosed with ADHD, one out of every three patients was in a deficient nutritional situation (subnutrition or malnutrition). Continued treatment with MTF-OROS for 30 months had a negative influence on height, which could perhaps be attenuated by improving the patients' nutrition.

MFP scanner diagnostics using a self-printed target to measure the modulation transfer function

NASA Astrophysics Data System (ADS)

Wang, Weibao; Bauer, Peter; Wagner, Jerry; Allebach, Jan P.

2014-01-01

In the current market, reduction of warranty costs is an important avenue for improving profitability by manufacturers of printer products. Our goal is to develop an autonomous capability for diagnosis of printer and scanner caused defects with mid-range laser multifunction printers (MFPs), so as to reduce warranty costs. If the scanner unit of the MFP is not performing according to specification, this issue needs to be diagnosed. If there is a print quality issue, this can be diagnosed by printing a special test page that is resident in the firmware of the MFP unit, and then scanning it. However, the reliability of this process will be compromised if the scanner unit is defective. Thus, for both scanner and printer image quality issues, it is important to be able to properly evaluate the scanner performance. In this paper, we consider evaluation of the scanner performance by measuring its modulation transfer function (MTF). The MTF is a fundamental tool for assessing the performance of imaging systems. Several ways have been proposed to measure the MTF, all of which require a special target, for example a slanted-edge target. It is unacceptably expensive to ship every MFP with such a standard target, and to expect that the customer can keep track of it. To reduce this cost, in this paper, we develop new approach to this task. It is based on a self-printed slanted-edge target. Then, we propose algorithms to improve the results using a self-printed slanted-edge target. Finally, we present experimental results for MTF measurement using self-printed targets and compare them to the results obtained with standard targets.

Effect of minoxidil topical foam on frontotemporal and vertex androgenetic alopecia in men: a 104-week open-label clinical trial.

PubMed

Kanti, V; Hillmann, K; Kottner, J; Stroux, A; Canfield, D; Blume-Peytavi, U

2016-07-01

Topical minoxidil formulations have been shown to be effective in treating androgenetic alopecia (AGA) for 12 months. Efficacy and safety in both frontotemporal and vertex regions over longer application periods have not been studied so far. To evaluate the effect of 5% minoxidil topical foam (5% MTF) in the frontotemporal and vertex areas in patients with moderate AGA over 104 weeks. An 80-week, open-label extension phase was performed, following a 24-week randomized, double-blind, placebo-controlled study in men with AGA grade IIIvertex to VI. Group 1 (n = 22) received ongoing 5% MTF for 104 weeks, Group 2 (n = 23) received placebo topical foam (plaTF) until week 24, followed by 5% MTF until week 104 during the extension phase. Frontotemporal and vertex target area non-vellus hair counts (f-TAHC, v-TAHC) and cumulative hair width (f-TAHW, v-TAHW) were assessed at baseline and at weeks 24, 52, 76 and 104. In Group 1, f-TAHW and f-TAHC showed a statistically significant increase from baseline to week 52 and week 76, respectively, returning to values comparable to baseline at week 104. No significant differences were found between baseline and week 104 in v-TAHC in Group 1 as well as f-TAHC, v-TAHC, f-TAHW and v-TAHW values in Group 2. 5% MTF is effective in stabilizing hair density, hair width and scalp coverage in both frontotemporal and vertex areas over an application period of 104 weeks, while showing a good safety and tolerability profile with a low rate of irritant contact dermatitis. © 2015 European Academy of Dermatology and Venereology.

How Question Types Reveal Student Thinking: An Experimental Comparison of Multiple-True-False and Free-Response Formats.

PubMed

Hubbard, Joanna K; Potts, Macy A; Couch, Brian A

2017-01-01

Assessments represent an important component of undergraduate courses because they affect how students interact with course content and gauge student achievement of course objectives. To make decisions on assessment design, instructors must understand the affordances and limitations of available question formats. Here, we use a crossover experimental design to identify differences in how multiple-true-false (MTF) and free-response (FR) exam questions reveal student thinking regarding specific conceptions. We report that correct response rates correlate across the two formats but that a higher percentage of students provide correct responses for MTF questions. We find that MTF questions reveal a high prevalence of students with mixed (correct and incorrect) conceptions, while FR questions reveal a high prevalence of students with partial (correct and unclear) conceptions. These results suggest that MTF question prompts can direct students to address specific conceptions but obscure nuances in student thinking and may overestimate the frequency of particular conceptions. Conversely, FR questions provide a more authentic portrait of student thinking but may face limitations in their ability to diagnose specific, particularly incorrect, conceptions. We further discuss an intrinsic tension between question structure and diagnostic capacity and how instructors might use multiple formats or hybrid formats to overcome these obstacles. © 2017 J. K. Hubbard et al. CBE—Life Sciences Education © 2017 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

An acute, double-blind, placebo-controlled cross-over study of 320 mg and 640 mg doses of Bacopa monnieri (CDRI 08) on multitasking stress reactivity and mood.

PubMed

Benson, Sarah; Downey, Luke A; Stough, Con; Wetherell, Mark; Zangara, Andrea; Scholey, Andrew

2014-04-01

Little research exists in humans concerning the anxiolytic, antidepressant, sedative, and adaptogenic actions the traditional Ayurvedic medicine Bacopa monnieri (BM) possesses in addition to its documented cognitive-enhancing effects. Preclinical work has identified a number of acute anxiolytic, nootropic, and adaptogenic effects of BM that may also co-occur in humans. The current double-blind, placebo-controlled cross-over study assessed the acute effects of a specific extract of BM (KeenMind® - CDRI 08) in normal healthy participants during completion of a multitasking framework (MTF). Seventeen healthy volunteers completed the MTF, at baseline, then 1 h and 2 h after consuming a placebo, 320 mg BM and 640 mg of BM. Treatments were separated by a 7-day washout with order determined by Latin Square. Outcome measures included cognitive outcomes from the MTF, with mood and salivary cortisol measured before and after each completion of the MTF. Change from baseline scores indicated positive cognitive effects, notably at both 1 h post and 2 h post BM consumption on the Letter Search and Stroop tasks, suggesting an earlier nootropic effect of BM than previously investigated. There were also some positive mood effects and reduction in cortisol levels, pointing to a physiological mechanism for stress reduction associated with BM consumption. It was concluded that acute BM supplementation produced some adaptogenic and nootropic effects that need to be replicated in a larger sample and in isolation from stressful cognitive tests in order to quantify the magnitude of these effects. The study was registered with the Australian and New Zealand Clinical Trials Registry (ACTRN12612000834853). Copyright © 2013 John Wiley & Sons, Ltd.

A novel EPID design for enhanced contrast and detective quantum efficiency

NASA Astrophysics Data System (ADS)

Rottmann, Joerg; Morf, Daniel; Fueglistaller, Rony; Zentai, George; Star-Lack, Josh; Berbeco, Ross

2016-09-01

Beams-eye-view imaging applications such as real-time soft-tissue motion estimation are hindered by the inherently low image contrast of electronic portal imaging devices (EPID) currently available for clinical use. We introduce and characterize a novel EPID design that provides substantially increased detective quantum efficiency (DQE), contrast-to-noise ratio (CNR) and sensitivity without degradation in spatial resolution. The prototype design features a stack of four conventional EPID layers combined with low noise integrated readout electronics. Each layer consists of a copper plate, a scintillator (\\text{G}{{\\text{d}}2}{{\\text{O}}2}{{\\text{S}}{}}\\text{:Tb} ) and a photodiode/TFT-switch (aSi:H). We characterize the prototype’s signal response to a 6 MV photon beam in terms of modulation transfer function (MTF), DQE and CNR. The presampled MTF is estimated using a slanted slit technique, the DQE is calculated from measured normalized noise power spectra (nNPS) and the MTF and CNR is estimated using a Las Vegas contrast phantom. The prototype has been designed and built to be interchangeable with the current clinical EPID on the Varian TrueBeam platform (AS-1200) in terms of size and data output specifications. Performance evaluation is conducted in absolute values as well as in relative terms using the Varian AS-1200 EPID as a reference detector. A fivefold increase of DQE(0) to about 6.7% was observed by using the four-layered design versus the AS-1200 reference detector. No substantial differences are observed between each layer’s individual MTF and the one for all four layers operating combined indicating that defocusing due to beam divergence is negligible. Also, using four layers instead of one increases the signal to noise ratio by a factor of 1.7.

Mental health of transgender youth in care at an adolescent urban community health center: a matched retrospective cohort study.

PubMed

Reisner, Sari L; Vetters, Ralph; Leclerc, M; Zaslow, Shayne; Wolfrum, Sarah; Shumer, Daniel; Mimiaga, Matthew J

2015-03-01

Transgender youth represent a vulnerable population at risk for negative mental health outcomes including depression, anxiety, self-harm, and suicidality. Limited data exist to compare the mental health of transgender adolescents and emerging adults to cisgender youth accessing community-based clinical services; the present study aimed to fill this gap. A retrospective cohort study of electronic health record data from 180 transgender patients aged 12-29 years seen between 2002 and 2011 at a Boston-based community health center was performed. The 106 female-to-male (FTM) and 74 male-to-female (MTF) patients were matched on gender identity, age, visit date, and race/ethnicity to cisgender controls. Mental health outcomes were extracted and analyzed using conditional logistic regression models. Logistic regression models compared FTM with MTF youth on mental health outcomes. The sample (N = 360) had a mean age of 19.6 years (standard deviation, 3.0); 43% white, 33% racial/ethnic minority, and 24% race/ethnicity unknown. Compared with cisgender matched controls, transgender youth had a twofold to threefold increased risk of depression, anxiety disorder, suicidal ideation, suicide attempt, self-harm without lethal intent, and both inpatient and outpatient mental health treatment (all p < .05). No statistically significant differences in mental health outcomes were observed comparing FTM and MTF patients, adjusting for age, race/ethnicity, and hormone use. Transgender youth were found to have a disparity in negative mental health outcomes compared with cisgender youth, with equally high burden in FTM and MTF patients. Identifying gender identity differences in clinical settings and providing appropriate services and supports are important steps in addressing this disparity. Copyright © 2015 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Evaluation of the technical performance of three different commercial digital breast tomosynthesis systems in the clinical environment.

PubMed

Rodríguez-Ruiz, A; Castillo, M; Garayoa, J; Chevalier, M

2016-06-01

The aim of this work was to research and evaluate the performance of three different digital breast tomosynthesis (DBT) systems in the clinical environment (Siemens Mammomat Inspiration, Hologic Selenia Dimensions, and Fujifilm Amulet Innovality). The characterization included the study of the detector, the automatic exposure control, and the resolution of DBT projections and reconstructed planes. The modulation transfer function (MTF) of the DBT projections was measured with a 1mm thick steel edge, showing a strong anisotropy (30-40% lower MTF0.5 frequencies in the tube travel direction). The in-plane MTF0.5, measured with a 25μm tungsten wire, ranges from 1.3 to 1.8lp/mm in the tube-travel direction and between 2.4 and 3.7lp/mm in the chest wall-nipple. In the latter direction, the MTF peak shift is more emphasized for large angular range systems (2.0 versus 1.0lp/mm). In-depth resolution of the planes, via the full width at half maximum (FWHM) from the point spread function of a 25μm tungsten wire, is not only influenced by angular range and yields 1.3-4.6mm among systems. The artifact spread function from 1mm diameter tungsten beads depends mainly on angular range, yielding two tendencies whether large (FWHM is 4.5mm) or small (FWHM is 10mm) angular range is used. DBT delivers per scan a mean glandular dose between 1.4 and 2.7mGy for a 45mm thick polymethyl methacrylate (PMMA) block. In conclusion, we have identified and analysed specific metrics that can be used for quality assurance of DBT systems. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

In-vivo detectability index: development and validation of an automated methodology

NASA Astrophysics Data System (ADS)

Smith, Taylor Brunton; Solomon, Justin; Samei, Ehsan

2017-03-01

The purpose of this study was to develop and validate a method to estimate patient-specific detectability indices directly from patients' CT images (i.e., "in vivo"). The method works by automatically extracting noise (NPS) and resolution (MTF) properties from each patient's CT series based on previously validated techniques. Patient images are thresholded into skin-air interfaces to form edge-spread functions, which are further binned, differentiated, and Fourier transformed to form the MTF. The NPS is likewise estimated from uniform areas of the image. These are combined with assumed task functions (reference function: 10 mm disk lesion with contrast of -15 HU) to compute detectability indices for a non-prewhitening matched filter model observer predicting observer performance. The results were compared to those from a previous human detection study on 105 subtle, hypo-attenuating liver lesions, using a two-alternative-forcedchoice (2AFC) method, over 6 dose levels using 16 readers. The in vivo detectability indices estimated for all patient images were compared to binary 2AFC outcomes with a generalized linear mixed-effects statistical model (Probit link function, linear terms only, no interactions, random term for readers). The model showed that the in vivo detectability indices were strongly predictive of 2AFC outcomes (P < 0.05). A linear comparison between the human detection accuracy and model-predicted detection accuracy (for like conditions) resulted in Pearson and Spearman correlations coefficients of 0.86 and 0.87, respectively. These data provide evidence that the in vivo detectability index could potentially be used to automatically estimate and track image quality in a clinical operation.

Using a two-step method to measure transgender identity in Latin America/the Caribbean, Portugal, and Spain.

PubMed

Reisner, Sari L; Biello, Katie; Rosenberger, Joshua G; Austin, S Bryn; Haneuse, Sebastien; Perez-Brumer, Amaya; Novak, David S; Mimiaga, Matthew J

2014-11-01

Few comparative data are available internationally to examine health differences by transgender identity. A barrier to monitoring the health and well-being of transgender people is the lack of inclusion of measures to assess natal sex/gender identity status in surveys. Data were from a cross-sectional anonymous online survey of members (n > 36,000) of a sexual networking website targeting men who have sex with men in Spanish- and Portuguese-speaking countries/territories in Latin America/the Caribbean, Portugal, and Spain. Natal sex/gender identity status was assessed using a two-step method (Step 1: assigned birth sex, Step 2: current gender identity). Male-to-female (MTF) and female-to-male (FTM) participants were compared to non-transgender males in age-adjusted regression models on socioeconomic status (SES) (education, income, sex work), masculine gender conformity, psychological health and well-being (lifetime suicidality, past-week depressive distress, positive self-worth, general self-rated health, gender related stressors), and sexual health (HIV-infection, past-year STIs, past-3 month unprotected anal or vaginal sex). The two-step method identified 190 transgender participants (0.54%; 158 MTF, 32 FTM). Of the 12 health-related variables, six showed significant differences between the three groups: SES, masculine gender conformity, lifetime suicidality, depressive distress, positive self-worth, and past-year genital herpes. A two-step approach is recommended for health surveillance efforts to assess natal sex/gender identity status. Cognitive testing to formally validate assigned birth sex and current gender identity survey items in Spanish and Portuguese is encouraged.

Using a Two-Step Method to Measure Transgender Identity in Latin America/the Caribbean, Portugal, and Spain

PubMed Central

Reisner, Sari L.; Biello, Katie; Rosenberger, Joshua G.; Austin, S. Bryn; Haneuse, Sebastien; Perez-Brumer, Amaya; Novak, David S.; Mimiaga, Matthew J.

2014-01-01

Few comparative data are available internationally to examine health differences by transgender identity. A barrier to monitoring the health and well-being of transgender people is the lack of inclusion of measures to assess natal sex/gender identity status in surveys. Data were from a cross-sectional anonymous online survey of members (n > 36,000) of a sexual networking website targeting men who have sex with men in Spanish- and Portuguese-speaking countries/ territories in Latin America/the Caribbean, Portugal, and Spain. Natal sex/gender identity status was assessed using a two-step method (Step 1: assigned birth sex, Step 2: current gender identity). Male-to-female (MTF) and female-to-male (FTM) participants were compared to non-transgender males in age-adjusted regression models on socioeconomic status (SES) (education, income, sex work), masculine gender conformity, psychological health and well-being (lifetime suicidality, past-week depressive distress, positive self-worth, general self-rated health, gender related stressors), and sexual health (HIV-infection, past-year STIs, past-3 month unprotected anal or vaginal sex). The two-step method identified 190 transgender participants (0.54%; 158 MTF, 32 FTM). Of the 12 health-related variables, six showed significant differences between the three groups: SES, masculine gender conformity, lifetime suicidality, depressive distress, positive self-worth, and past-year genital herpes. A two-step approach is recommended for health surveillance efforts to assess natal sex/gender identity status. Cognitive testing to formally validate assigned birth sex and current gender identity survey items in Spanish and Portuguese is encouraged. PMID:25030120

Potential benefit of the CT adaptive statistical iterative reconstruction method for pediatric cardiac diagnosis

NASA Astrophysics Data System (ADS)

Miéville, Frédéric A.; Ayestaran, Paul; Argaud, Christophe; Rizzo, Elena; Ou, Phalla; Brunelle, Francis; Gudinchet, François; Bochud, François; Verdun, Francis R.

2010-04-01

Adaptive Statistical Iterative Reconstruction (ASIR) is a new imaging reconstruction technique recently introduced by General Electric (GE). This technique, when combined with a conventional filtered back-projection (FBP) approach, is able to improve the image noise reduction. To quantify the benefits provided on the image quality and the dose reduction by the ASIR method with respect to the pure FBP one, the standard deviation (SD), the modulation transfer function (MTF), the noise power spectrum (NPS), the image uniformity and the noise homogeneity were examined. Measurements were performed on a control quality phantom when varying the CT dose index (CTDIvol) and the reconstruction kernels. A 64-MDCT was employed and raw data were reconstructed with different percentages of ASIR on a CT console dedicated for ASIR reconstruction. Three radiologists also assessed a cardiac pediatric exam reconstructed with different ASIR percentages using the visual grading analysis (VGA) method. For the standard, soft and bone reconstruction kernels, the SD is reduced when the ASIR percentage increases up to 100% with a higher benefit for low CTDIvol. MTF medium frequencies were slightly enhanced and modifications of the NPS shape curve were observed. However for the pediatric cardiac CT exam, VGA scores indicate an upper limit of the ASIR benefit. 40% of ASIR was observed as the best trade-off between noise reduction and clinical realism of organ images. Using phantom results, 40% of ASIR corresponded to an estimated dose reduction of 30% under pediatric cardiac protocol conditions. In spite of this discrepancy between phantom and clinical results, the ASIR method is as an important option when considering the reduction of radiation dose, especially for pediatric patients.

Three-dimensional cascaded system analysis of a 50 µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis.

PubMed

Zhao, C; Vassiljev, N; Konstantinidis, A C; Speller, R D; Kanicki, J

2017-03-07

High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 µm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g.  ±30°) improves the low spatial frequency (below 5 mm -1 ) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used. Theoretical analysis suggests that a pixelated scintillator in combination with the 50 µm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.

Remote Imaging of Earthquake Characteristics Along Oceanic Transforms

NASA Astrophysics Data System (ADS)

Cleveland, M.; Ammon, C. J.

2014-12-01

Compared with subduction and continental transform systems, many characteristics of oceanic transform faults (OTF) are better defined (first-order structure and composition, thermal properties, etc.). Still, many aspects of earthquake behavior along OTFs remain poorly understood as a result of their relative remoteness. But the substantial aseismic deformation (averaging roughly 85%) that occurs along OTFs and the implied interaction of aseismic with seismic deformation is an opportunity to explore fundamental earthquake nucleation and rupture processes. However, the study of OTF earthquake properties is not easy because these faults are often located in remote regions, lacking nearby seismic networks. Thus, many standard network-based seismic approaches are infeasible, but some can be adapted to the effort. For example, double-difference methods applied to cross-correlation measured Rayleigh wave time shifts is an effective tool to provide greatly improved relative epicentroid locations, origin-time shifts, and relative event magnitudes for earthquakes in remote regions. The same comparative waveform measurements can provide insight into rupture directivity of the larger OTF events. In this study, we calculate improved relative earthquake locations and magnitudes of earthquakes along the Blanco Fracture Zone in the northeast Pacific Ocean and compare and contrast that work with a study of the more remote Menard Transform Fault (MTF), located in the southeast Pacific Ocean. For the Blanco, we work exclusively with Rayleigh (R1) observations exploiting the dense networks in the northern hemisphere. For the MTF, we combine R1 with Love (G1) observations to map and to analyze the distribution of strong asperities along this remote, 200-km-long fault. Specifically, we attempt to better define the relationship between observed near-transform normal and vertical strike-slip earthquakes in the vicinity of the MTF. We test our ability to use distant observations (the closest station is about 2,500 km distant) to constrain rupture characteristics of recent strong earthquakes in the region. We compare the seismicity characteristics along the faults to explore the relationship of fault age and morphology on rupture behavior.

Three-dimensional cascaded system analysis of a 50 µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Zhao, C.; Vassiljev, N.; Konstantinidis, A. C.; Speller, R. D.; Kanicki, J.

2017-03-01

High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 µm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g.  ±30°) improves the low spatial frequency (below 5 mm-1) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used. Theoretical analysis suggests that a pixelated scintillator in combination with the 50 µm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.

Automated Verification of Spatial Resolution in Remotely Sensed Imagery

NASA Technical Reports Server (NTRS)

Davis, Bruce; Ryan, Robert; Holekamp, Kara; Vaughn, Ronald

2011-01-01

Image spatial resolution characteristics can vary widely among sources. In the case of aerial-based imaging systems, the image spatial resolution characteristics can even vary between acquisitions. In these systems, aircraft altitude, speed, and sensor look angle all affect image spatial resolution. Image spatial resolution needs to be verified with estimators that include the ground sample distance (GSD), the modulation transfer function (MTF), and the relative edge response (RER), all of which are key components of image quality, along with signal-to-noise ratio (SNR) and dynamic range. Knowledge of spatial resolution parameters is important to determine if features of interest are distinguishable in imagery or associated products, and to develop image restoration algorithms. An automated Spatial Resolution Verification Tool (SRVT) was developed to rapidly determine the spatial resolution characteristics of remotely sensed aerial and satellite imagery. Most current methods for assessing spatial resolution characteristics of imagery rely on pre-deployed engineered targets and are performed only at selected times within preselected scenes. The SRVT addresses these insufficiencies by finding uniform, high-contrast edges from urban scenes and then using these edges to determine standard estimators of spatial resolution, such as the MTF and the RER. The SRVT was developed using the MATLAB programming language and environment. This automated software algorithm assesses every image in an acquired data set, using edges found within each image, and in many cases eliminating the need for dedicated edge targets. The SRVT automatically identifies high-contrast, uniform edges and calculates the MTF and RER of each image, and when possible, within sections of an image, so that the variation of spatial resolution characteristics across the image can be analyzed. The automated algorithm is capable of quickly verifying the spatial resolution quality of all images within a data set, enabling the appropriate use of those images in a number of applications.

High resolution optical surface metrology with the slope measuring portable optical test system

NASA Astrophysics Data System (ADS)

Maldonado, Alejandro V.

New optical designs strive to achieve extreme performance, and continually increase the complexity of prescribed optical shapes, which often require wide dynamic range and high resolution. SCOTS, or the Software Configurable Optical Test System, can measure a wide range of optical surfaces with high sensitivity using surface slope. This dissertation introduces a high resolution version of SCOTS called SPOTS, or the Slope measuring Portable Optical Test System. SPOTS improves the metrology of surface features on the order of sub-millimeter to decimeter spatial scales and nanometer to micrometer level height scales. Currently there is no optical surface metrology instrument with the same utility. SCOTS uses a computer controlled display (such as an LCD monitor) and camera to measure surface slopes over the entire surface of a mirror. SPOTS differs in that an additional lens is placed near the surface under test. A small prototype system is discussed in general, providing the support for the design of future SPOTS devices. Then the SCOTS instrument transfer function is addressed, which defines the way the system filters surface heights. Lastly, the calibration and performance of larger SPOTS device is analyzed with example measurements of the 8.4-m diameter aspheric Large Synoptic Survey Telescope's (LSST) primary mirror. In general optical systems have a transfer function, which filters data. In the case of optical imaging systems the instrument transfer function (ITF) follows the modulation transfer function (MTF), which causes a reduction of contrast as a function of increasing spatial frequency due to diffraction. In SCOTS, ITF is shown to decrease the measured height of surface features as their spatial frequency increases, and thus the SCOTS and SPOTS ITF is proportional to their camera system's MTF. Theory and simulations are supported by a SCOTS measurement of a test piece with a set of lithographically written sinusoidal surface topographies. In addition, an example of a simple inverse filtering technique is provided. The success of a small SPOTS proof of concept instrument paved the way for a new larger prototype system, which is intended to measure subaperture regions on large optical mirrors. On large optics, the prototype SPOTS is light weight and it rests on the surface being tested. One advantage of this SPOTS is stability over time in maintaining its calibration. Thus the optician can simply place SPOTS on the mirror, perform a simple alignment, collect measurement data, then pick the system up and repeat at a new location. The entire process takes approximately 5 to 10 minutes, of which 3 minutes is spent collecting data. SPOTS' simplicity of design, light weight, robustness, wide dynamic range, and high sensitivity make it a useful tool for optical shop use during the fabrication and testing process of large and small optics.

Joint Interoperability of Tactical Command and Control Systems (JINTACCS) Technical Interface Design Plan (Test Edition). Appendix C. Glossary

DTIC Science & Technology

1981-03-01

m u z r- Z > H < m ff -< C 2 C) 2 3 r- c is o 1 L_ • o > • en • • • Ŕ O > 00 o 30 n 30 T r- 1> - n o > IDE N T S E LIN E D IT...responsibilities to the Defense Intelligence Agency ( DIA ), the Services, and the unified and specified commands for carrying out that guidance. 3 - JCS...Testing 1-2 1.4 JINTACCS Message Text Eorinats (MTF) and TADIL Messages 1-2 1.4.1 JINTACCS Message Text Formats (MTF) 1- 3 1.4.2 Developmental TADIL

Determination of modulation transfer function of a printer by measuring the autocorrelation of the transmission function of a printed Ronchi grating

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

Madanipour, Khosro; Tavassoly, Mohammad T

2009-02-01

We show theoretically and verify experimentally that the modulation transfer function (MTF) of a printing system can be determined by measuring the autocorrelation of a printed Ronchi grating. In practice, two similar Ronchi gratings are printed on two transparencies and the transparencies are superimposed with parallel grating lines. Then, the gratings are uniformly illuminated and the transmitted light from a large section is measured versus the displacement of one grating with respect to the other in a grating pitch interval. This measurement provides the required autocorrelation function for determination of the MTF.

Effect of aberrations in human eye on contrast sensitivity function

NASA Astrophysics Data System (ADS)

Quan, Wei; Wang, Feng-lin; Wang, Zhao-qi

2011-06-01

The quantitative analysis of the effect of aberrations in human eye on vision has important clinical value in the correction of aberrations. The wave-front aberrations of human eyes were measured with the Hartmann-Shack wave-front sensor and modulation transfer function (MTF) was computed from the wave-front aberrations. Contrast sensitivity function (CSF) was obtained from MTF and the retinal aerial image modulation (AIM). It is shown that the 2nd, 3rd, 4th, 5th, 6th Zernike aberrations deteriorate contrast sensitivity function. When the 2nd, 3rd, 4th, 5th, 6th Zernike aberrations are corrected high contrast sensitivity function can be obtained.

A high density field reversed configuration (FRC) target for magnetized target fusion: First internal profile measurements of a high density FRC

NASA Astrophysics Data System (ADS)

Intrator, T.; Zhang, S. Y.; Degnan, J. H.; Furno, I.; Grabowski, C.; Hsu, S. C.; Ruden, E. L.; Sanchez, P. G.; Taccetti, J. M.; Tuszewski, M.; Waganaar, W. J.; Wurden, G. A.

2004-05-01

Magnetized target fusion (MTF) is a potentially low cost path to fusion, intermediate in plasma regime between magnetic and inertial fusion energy. It requires compression of a magnetized target plasma and consequent heating to fusion relevant conditions inside a converging flux conserver. To demonstrate the physics basis for MTF, a field reversed configuration (FRC) target plasma has been chosen that will ultimately be compressed within an imploding metal liner. The required FRC will need large density, and this regime is being explored by the FRX-L (FRC-Liner) experiment. All theta pinch formed FRCs have some shock heating during formation, but FRX-L depends further on large ohmic heating from magnetic flux annihilation to heat the high density (2-5×1022m-3), plasma to a temperature of Te+Ti≈500 eV. At the field null, anomalous resistivity is typically invoked to characterize the resistive like flux dissipation process. The first resistivity estimate for a high density collisional FRC is shown here. The flux dissipation process is both a key issue for MTF and an important underlying physics question.

Lower bound for LCD image quality

NASA Astrophysics Data System (ADS)

Olson, William P.; Balram, Nikhil

1996-03-01

The paper presents an objective lower bound for the discrimination of patterns and fine detail in images on a monochrome LCD. In applications such as medical imaging and military avionics the information of interest is often at the highest frequencies in the image. Since LCDs are sampled data systems, their output modulation is dependent on the phase between the input signal and the sampling points. This phase dependence becomes particularly significant at high spatial frequencies. In order to use an LCD for applications such as those mentioned above it is essential to have a lower (worst case) bound on the performance of the display. We address this problem by providing a mathematical model for the worst case output modulation of an LCD in response to a sine wave input. This function can be interpreted as a worst case modulation transfer function (MTF). The intersection of the worst case MTF with the contrast threshold function (CTF) of the human visual system defines the highest spatial frequency that will always be detectable. In addition to providing the worst case limiting resolution, this MTF is combined with the CTF to produce objective worst case image quality values using the modulation transfer function area (MTFA) metric.

Amplitude modulation detection by human listeners in reverberant sound fields: Carrier bandwidth effects and binaural versus monaural comparison.

PubMed

Zahorik, Pavel; Kim, Duck O; Kuwada, Shigeyuki; Anderson, Paul W; Brandewie, Eugene; Collecchia, Regina; Srinivasan, Nirmal

2012-06-01

Previous work [Zahorik et al., POMA, 12, 050005 (2011)] has reported that for a broadband noise carrier signal in a simulated reverberant sound field, human sensitivity to amplitude modulation (AM) is higher than would be predicted based on the broadband acoustical modulation transfer function (MTF) of the listening environment. Interpretation of this result was complicated by the fact that acoustical MTFs of rooms are often quite different for different carrier frequency regions, and listeners may have selectively responded to advantageous carrier frequency regions where the effective acoustic modulation loss due to the room was less than indicated by a broadband acoustic MTF analysis. Here, AM sensitivity testing and acoustic MTF analyses were expanded to include narrowband noise carriers (1-octave and 1/3-octave bands centered at 4 kHz), as well as monaural and binaural listening conditions. Narrowband results were found to be consistent with broadband results: In a reverberant sound field, human AM sensitivity is higher than indicated by the acoustical MTFs. The effect was greatest for modulation frequencies above 32 Hz and was present whether the stimulation was monaural or binaural. These results are suggestive of mechanisms that functionally enhance modulation in reverberant listening.

Structural Connectivity Networks of Transgender People

PubMed Central

Hahn, Andreas; Kranz, Georg S.; Küblböck, Martin; Kaufmann, Ulrike; Ganger, Sebastian; Hummer, Allan; Seiger, Rene; Spies, Marie; Winkler, Dietmar; Kasper, Siegfried; Windischberger, Christian; Swaab, Dick F.; Lanzenberger, Rupert

2015-01-01

Although previous investigations of transsexual people have focused on regional brain alterations, evaluations on a network level, especially those structural in nature, are largely missing. Therefore, we investigated the structural connectome of 23 female-to-male (FtM) and 21 male-to-female (MtF) transgender patients before hormone therapy as compared with 25 female and 25 male healthy controls. Graph theoretical analysis of whole-brain probabilistic tractography networks (adjusted for differences in intracranial volume) showed decreased hemispheric connectivity ratios of subcortical/limbic areas for both transgender groups. Subsequent analysis revealed that this finding was driven by increased interhemispheric lobar connectivity weights (LCWs) in MtF transsexuals and decreased intrahemispheric LCWs in FtM patients. This was further reflected on a regional level, where the MtF group showed mostly increased local efficiencies and FtM patients decreased values. Importantly, these parameters separated each patient group from the remaining subjects for the majority of significant findings. This work complements previously established regional alterations with important findings of structural connectivity. Specifically, our data suggest that network parameters may reflect unique characteristics of transgender patients, whereas local physiological aspects have been shown to represent the transition from the biological sex to the actual gender identity. PMID:25217469

Exploring barriers and facilitators to participation of male-to-female transgender persons in preventive HIV vaccine clinical trials.

PubMed

Andrasik, Michele Peake; Yoon, Ro; Mooney, Jessica; Broder, Gail; Bolton, Marcus; Votto, Teress; Davis-Vogel, Annet

2014-06-01

Observed seroincidence and prevalence rates in male-to-female (MTF) transgender individuals highlight the need for effective targeted HIV prevention strategies for this community. In order to develop an effective vaccine that can be used by transgender women, researchers must understand and address existing structural issues that present barriers to this group's participation in HIV vaccine clinical trials. Overcoming barriers to participation is important for ensuring HIV vaccine acceptability and efficacy for the MTF transgender community. To explore barriers and facilitators to MTF transgender participation in preventive HIV vaccine clinical trials, the HIV Vaccine Trials Network conducted focus groups among transgender women in four urban areas (Atlanta, Boston, Philadelphia, and San Francisco). Barriers and facilitators to engagement of transgender women in preventive HIV vaccine clinical trials led to the following recommendations: (a) transgender cultural competency training, (b) creating trans-friendly environments, (c) true partnerships with local trans-friendly organizations and health care providers, (d) protocols that focus on transgender specific issues, and (e) data collection and tracking of transgender individuals. These results have implications for the conduct of HIV vaccine trials, as well as engagement of transgender women in research programs in general.

A Review of the Status of Brain Structure Research in Transsexualism.

PubMed

Guillamon, Antonio; Junque, Carme; Gómez-Gil, Esther

2016-10-01

The present review focuses on the brain structure of male-to-female (MtF) and female-to-male (FtM) homosexual transsexuals before and after cross-sex hormone treatment as shown by in vivo neuroimaging techniques. Cortical thickness and diffusion tensor imaging studies suggest that the brain of MtFs presents complex mixtures of masculine, feminine, and demasculinized regions, while FtMs show feminine, masculine, and defeminized regions. Consequently, the specific brain phenotypes proposed for MtFs and FtMs differ from those of both heterosexual males and females. These phenotypes have theoretical implications for brain intersexuality, asymmetry, and body perception in transsexuals as well as for Blanchard's hypothesis on sexual orientation in homosexual MtFs. Falling within the aegis of the neurohormonal theory of sex differences, we hypothesize that cortical differences between homosexual MtFs and FtMs and male and female controls are due to differently timed cortical thinning in different regions for each group. Cross-sex hormone studies have reported marked effects of the treatment on MtF and FtM brains. Their results are used to discuss the early postmortem histological studies of the MtF brain.

Transgender Surgery in Denmark From 1994 to 2015: 20-Year Follow-Up Study.

PubMed

Aydin, Dogu; Buk, Liv Johanne; Partoft, Søren; Bonde, Christian; Thomsen, Michael Vestergaard; Tos, Tina

2016-04-01

Gender dysphoria is a mismatch between a person's biological sex and gender identity. The best treatment is believed to be hormonal therapy and gender-confirming surgery that will transition the individual toward the desired gender. Treatment in Denmark is covered by public health care, and gender-confirming surgery in Denmark is centralized at a single-center with few specialized plastic surgeons conducting top surgery (mastectomy or breast augmentation) and bottom surgery (vaginoplasty or phalloplasty and metoidioplasty). To report the first nationwide single-center review on transsexual patients in Denmark undergoing gender-confirming surgery performed by a single surgical team and to assess whether age at time of gender-confirming surgery decreased during a 20-year period. Electronic patient databases were used to identify patients diagnosed with gender identity disorders from January 1994 through March 2015. Patients were excluded from the study if they were pseudohermaphrodites or if their gender was not reported. Gender distribution, age trends, and surgeries performed for Danish patients who underwent gender-confirming surgery. One hundred fifty-eight patients referred for gender-confirming surgery were included. Fifty-five cases (35%) were male-to-female (MtF) and 103 (65%) were female-to-male (FtM). In total, 126 gender-confirming surgeries were performed. For FtM cases, top surgery (mastectomy) was conducted in 62 patients and bottom surgery (phalloplasty and metoidioplasty) was conducted in 17 patients. For MtF cases, 45 underwent bottom surgery (vaginoplasty), 2 of whom received breast augmentation. The FtM:MtF ratio of the referred patients was 1.9:1. The median age at the time of surgery decreased from 40 to 27 years during the 20-year period. Gender-confirming surgery was performed on 65 FtM and 40 MtF cases at our hospital, and 21 transsexuals underwent surgery abroad. Mastectomy was performed in 62 FtM and bottom surgery in 17 FtM cases. Vaginoplasty was performed in 45 MtF and breast augmentation in 2 MtF cases. There was a significant decrease in age at the time of gender-confirming surgery during the course of the study period. Copyright © 2016 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

Optimization technique of wavefront coding system based on ZEMAX externally compiled programs

NASA Astrophysics Data System (ADS)

Han, Libo; Dong, Liquan; Liu, Ming; Zhao, Yuejin; Liu, Xiaohua

2016-10-01

Wavefront coding technique as a means of athermalization applied to infrared imaging system, the design of phase plate is the key to system performance. This paper apply the externally compiled programs of ZEMAX to the optimization of phase mask in the normal optical design process, namely defining the evaluation function of wavefront coding system based on the consistency of modulation transfer function (MTF) and improving the speed of optimization by means of the introduction of the mathematical software. User write an external program which computes the evaluation function on account of the powerful computing feature of the mathematical software in order to find the optimal parameters of phase mask, and accelerate convergence through generic algorithm (GA), then use dynamic data exchange (DDE) interface between ZEMAX and mathematical software to realize high-speed data exchanging. The optimization of the rotational symmetric phase mask and the cubic phase mask have been completed by this method, the depth of focus increases nearly 3 times by inserting the rotational symmetric phase mask, while the other system with cubic phase mask can be increased to 10 times, the consistency of MTF decrease obviously, the maximum operating temperature of optimized system range between -40°-60°. Results show that this optimization method can be more convenient to define some unconventional optimization goals and fleetly to optimize optical system with special properties due to its externally compiled function and DDE, there will be greater significance for the optimization of unconventional optical system.

Characterization of a clinical unit for digital radiography based on irradiation side sampling technology

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

Rivetti, Stefano; Lanconelli, Nico; Bertolini, Marco

2013-10-15

Purpose: A characterization of a clinical unit for digital radiography (FUJIFILM FDR D-EVO) is presented. This system is based on the irradiation side sampling (ISS) technology and can be equipped with two different scintillators: one traditional gadolinium-oxysulphide phosphor (GOS) and a needle structured cesium iodide (CsI) phosphor panel.Methods: The characterization was achieved in terms of response curve, modulation transfer function (MTF), noise power spectra (NPS), detective quantum efficiency (DQE), and psychophysical parameters (contrast-detail analysis with an automatic reading of CDRAD images). For both scintillation screens the authors accomplished the measurements with four standard beam conditions: RAQ3, RQA5, RQA7, and RQA9.Results:more » At the Nyquist frequency (3.33 lp/mm) the MTF is about 35% and 25% for CsI and GOS detectors, respectively. The CsI scintillator has better noise properties than the GOS screen in almost all the conditions. This is particularly true for low-energy beams, where the noise for the GOS system can go up to a factor 2 greater than that found for CsI. The DQE of the CsI detector reaches a peak of 60%, 60%, 58%, and 50% for the RQA3, RQA5, RQA7, and RQA9 beams, respectively, whereas for the GOS screen the maximum DQE is 40%, 44%, 44%, and 35%. The contrast-detail analysis confirms that in the majority of cases the CsI scintillator is able to provide improved outcomes to those obtained with the GOS screen.Conclusions: The limited diffusion of light produced by the ISS reading makes possible the achievement of very good spatial resolution. In fact, the MTF of the unit with the CsI panel is only slightly lower to that achieved with direct conversion detectors. The combination of very good spatial resolution, together with the good noise properties reached with the CsI screen, allows achieving DQE on average about 1.5 times greater than that obtained with GOS. In fact, the DQE of unit equipped with CsI is comparable to the best alternative methods available which are based on the same technology, and similar to others based on an a-Se direct conversion detectors.« less

Intra-ocular lens optical changes resulting from the loading of dexamethasone.

PubMed

Artigas, José M; García-Domene, M Carmen; Navea, Amparo; Botella, Pablo; Fernández, Eduardo

2017-10-01

To study the optical changes on hydrogel-silicone intraocular lenses (IOLs) resulting from loading them with dexamethasone. We used prototype hydrogel(pHEMA)-silicone IOLs and loaded the matrices with an anti-inflammatory drug (dexamethasone). The optical properties we analyzed experimentally were a) modulation transfer function (MTF); b) spectral transmission; c) diopter power. These determinations were performed on drug-loaded IOLs, IOLs that had released the drug, and IOLs that had not been drug-loaded. Loading a hydrogel-silicone IOL with dexamethasone results in impairment of its optical qualities, in particular its MTF and spectral transmission, but not dioptric power. However, once the drug has been released, it almost recovers its initial optical properties.

Intra-ocular lens optical changes resulting from the loading of dexamethasone

PubMed Central

Artigas, José M.; García-Domene, M. Carmen; Navea, Amparo; Botella, Pablo; Fernández, Eduardo

2017-01-01

To study the optical changes on hydrogel-silicone intraocular lenses (IOLs) resulting from loading them with dexamethasone. We used prototype hydrogel(pHEMA)-silicone IOLs and loaded the matrices with an anti-inflammatory drug (dexamethasone). The optical properties we analyzed experimentally were a) modulation transfer function (MTF); b) spectral transmission; c) diopter power. These determinations were performed on drug-loaded IOLs, IOLs that had released the drug, and IOLs that had not been drug-loaded. Loading a hydrogel-silicone IOL with dexamethasone results in impairment of its optical qualities, in particular its MTF and spectral transmission, but not dioptric power. However, once the drug has been released, it almost recovers its initial optical properties. PMID:29082089

Minimum resolvable power contrast model

NASA Astrophysics Data System (ADS)

Qian, Shuai; Wang, Xia; Zhou, Jingjing

2018-01-01

Signal-to-noise ratio and MTF are important indexs to evaluate the performance of optical systems. However,whether they are used alone or joint assessment cannot intuitively describe the overall performance of the system. Therefore, an index is proposed to reflect the comprehensive system performance-Minimum Resolvable Radiation Performance Contrast (MRP) model. MRP is an evaluation model without human eyes. It starts from the radiance of the target and the background, transforms the target and background into the equivalent strips,and considers attenuation of the atmosphere, the optical imaging system, and the detector. Combining with the signal-to-noise ratio and the MTF, the Minimum Resolvable Radiation Performance Contrast is obtained. Finally the detection probability model of MRP is given.

Resolution Properties of a Calcium Tungstate (CaWO4) Screen Coupled to a CMOS Imaging Detector

NASA Astrophysics Data System (ADS)

Koukou, Vaia; Martini, Niki; Valais, Ioannis; Bakas, Athanasios; Kalyvas, Nektarios; Lavdas, Eleftherios; Fountos, George; Kandarakis, Ioannis; Michail, Christos

2017-11-01

The aim of the current work was to assess the resolution properties of a calcium tungstate (CaWO4) screen (screen coating thickness: 50.09 mg/cm2, actual thickness: 167.2 μm) coupled to a high resolution complementary metal oxide semiconductor (CMOS) digital imaging sensor. A 2.7x3.6 cm2 CaWO4 sample was extracted from an Agfa Curix universal screen and was coupled directly with the active area of the active pixel sensor (APS) CMOS sensor. Experiments were performed following the new IEC 62220-1-1:2015 International Standard, using an RQA-5 beam quality. Resolution was assessed in terms of the Modulation Transfer Function (MTF), using the slanted-edge method. The CaWO4/CMOS detector configuration was found with linear response, in the exposure range under investigation. The final MTF was obtained through averaging the oversampled edge spread function (ESF), using a custom-made software developed by our team, according to the IEC 62220-1-1:2015. Considering the renewed interest in calcium tungstate for various applications, along with the resolution results of this work, CaWO4 could be also considered for use in X-ray imaging devices such as charged-coupled devices (CCD) and CMOS.

Simulation of aspheric tolerance with polynomial fitting

NASA Astrophysics Data System (ADS)

Li, Jing; Cen, Zhaofeng; Li, Xiaotong

2018-01-01

The shape of the aspheric lens changes caused by machining errors, resulting in a change in the optical transfer function, which affects the image quality. At present, there is no universally recognized tolerance criterion standard for aspheric surface. To study the influence of aspheric tolerances on the optical transfer function, the tolerances of polynomial fitting are allocated on the aspheric surface, and the imaging simulation is carried out by optical imaging software. Analysis is based on a set of aspheric imaging system. The error is generated in the range of a certain PV value, and expressed as a form of Zernike polynomial, which is added to the aspheric surface as a tolerance term. Through optical software analysis, the MTF of optical system can be obtained and used as the main evaluation index. Evaluate whether the effect of the added error on the MTF of the system meets the requirements of the current PV value. Change the PV value and repeat the operation until the acceptable maximum allowable PV value is obtained. According to the actual processing technology, consider the error of various shapes, such as M type, W type, random type error. The new method will provide a certain development for the actual free surface processing technology the reference value.

Basic imaging properties of an indirect flat-panel detector system employing irradiation side sampling (ISS) technology for chest radiography: comparison with a computed radiographic system.

PubMed

Tanaka, Nobukazu; Yano, Yuki; Yabuuchi, Hidetake; Akasaka, Tsutomu; Sasaki, Masayuki; Ohki, Masafumi; Morishita, Junji

2013-01-01

The image quality and potential usefulness for patient skin-dose reduction of a newly developed flat-panel detector (FPD) system employing irradiation side sampling (ISS) were investigated and compared to a conventional computed radiography (CR) system. We used the X-ray beam quality of RQA 9 as noted in the standard evaluation method by the International Electrotechnical Commission 62220-1 to evaluate the image quality of the detector for chest radiography. The presampled modulation transfer function (MTF) of the ISS-FPD system was slightly higher than that of the CR system in the horizontal direction at more than 2.2 cycles/mm. However, the presampled MTF of the ISS-FPD system was slightly lower than that of the CR system in the vertical direction. The Wiener spectrum of the ISS-FPD system showed a 50-65 % lesser noise level than that of the CR system under the same exposure condition. The detective quantum efficiency of the ISS-FPD system was at least twice as great as that of the CR system. We conclude that the ISS-FPD system has the potential to reduce the patient skin dose compared to a conventional CR system for chest radiography.

SU-G-BRA-06: Quantification of Tracking Performance of a Multi-Layer Electronic Portal Imaging Device

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

Hu, Y; Rottmann, J; Myronakis, M

2016-06-15

Purpose: The purpose of this study was to quantify the improvement in tumor tracking, with and without fiducial markers, afforded by employing a multi-layer (MLI) electronic portal imaging device (EPID) over the current state-of-the-art, single-layer, digital megavolt imager (DMI) architecture. Methods: An ideal observer signal-to-noise ratio (d’) approach was used to quantify the ability of an MLI EPID and a current, state-of-the-art DMI EPID to track lung tumors from the treatment beam’s-eye-view. Using each detector modulation transfer function (MTF) and noise power spectrum (NPS) as inputs, a detection task was employed with object functions describing simple three-dimensional Cartesian shapes (spheresmore » and cylinders). Marker-less tumor tracking algorithms often use texture discrimination to differentiate benign and malignant tissue. The performance of such algorithms is simulated by employing a discrimination task for the ideal observer, which measures the ability of a system to differentiate two image quantities. These were defined as the measured textures for benign and malignant lung tissue. Results: The NNPS of the MLI ∼25% of that of the DMI at the expense of decreased MTF at intermediate frequencies (0.25≤« less

Image quality and stability of image-guided radiotherapy (IGRT) devices: A comparative study

PubMed Central

Stock, Markus; Pasler, Marlies; Birkfellner, Wolfgang; Homolka, Peter; Poetter, Richard; Georg, Dietmar

2010-01-01

Introduction Our aim was to implement standards for quality assurance of IGRT devices used in our department and to compare their performances with that of a CT simulator. Materials and methods We investigated image quality parameters for three devices over a period of 16 months. A multislice CT was used as a benchmark and results related to noise, spatial resolution, low contrast visibility (LCV) and uniformity were compared with a cone beam CT (CBCT) at a linac and simulator. Results All devices performed well in terms of LCV and, in fact, exceeded vendor specifications. MTF was comparable between CT and linac CBCT. Integral nonuniformity was, on average, 0.002 for the CT and 0.006 for the linac CBCT. Uniformity, LCV and MTF varied depending on the protocols used for the linac CBCT. Contrast-to-noise ratio was an average of 51% higher for the CT than for the linac and simulator CBCT. No significant time trend was observed and tolerance limits were implemented. Discussion Reasonable differences in image quality between CT and CBCT were observed. Further research and development are necessary to increase image quality of commercially available CBCT devices in order for them to serve the needs for adaptive and/or online planning. PMID:19695725

Early experience in the use of quantitative image quality measurements for the quality assurance of full field digital mammography x-ray systems

NASA Astrophysics Data System (ADS)

Marshall, N. W.

2007-09-01

Quantitative image quality results in the form of the modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE) are presented for nine full field digital mammography (FFDM) systems. These parameters are routinely measured as part of the quality assurance (QA) programme for the seven FFDM units covered by our centre. Just one additional image is required compared to the standard FFDM protocol; this is the image of an edge, from which the MTF is calculated. A variance image is formed from one of the flood images used to measure the detector response and this provides useful information on the condition of the detector with respect to artefacts. Finally, the NNPS is calculated from the flood image acquired at a target detector air kerma (DAK) of 100 µGy. DQE is then estimated from these data; however, no correction is currently made for effects of detector cover transmission on DQE. The coefficient of variation (cov) of the 50% point of the MTF for five successive MTF results was 1%, while the cov for the 50% MTF point for an a-Se system over a period of 17 months was approximately 3%. For four a-Se based systems, the cov for the NNPS at 1 mm-1 for a target DAK of 100 µGy was approximately 4%; the same result was found for four CsI based FFDM units. With regard to the stability of NNPS over time, the cov for four NNPS results acquired over a period of 12 months was also approximately 4%. The effect of acquisition geometry on NNPS was also assessed for a CsI based system. NNPS data acquired with the antiscatter grid in place showed increased noise at low spatial frequency; this effect was more severe as DAK increased. DQE results for the three detector types (a-Se, CsI and CR) are presented as a function of DAK. Some reduction in DQE was found for both the a-Se and CsI based systems at a target DAK of 12.5 µGy when compared to DQE data acquired at 100 µGy. For the CsI based systems, DQE at 1 mm-1 fell from 0.49 at 100 µGy to 0.38 at 12.5 µGy. For the a-Se units, there was a slightly greater reduction in average DQE at 1 mm-1, from 0.53 at 100 µGy to 0.31 at 12.5 µGy. Somewhat different behaviour was seen for the CR unit; DQE (at 1 mm-1) increased from 0.40 at 100 µGy to 0.49 at 12.5 µGy however, DQE fell to 0.30 at 420 µGy. DQE stability over time was assessed using the cov of DQE at 1 mm-1 and a target DAK of 100 µGy the cov for data acquired over a period of 17 months for an a-Se system was approximately 7%. For comparison with conventional testing methods, the cov was calculated for contrast-detail (cd) data acquired over the same period of time for this unit. The cov for the threshold contrast results (averaged for disc diameters between 0.1 mm and 2 mm) was 6%, indicating similar stability.

Comparative evaluation of toric intraocular lens alignment and visual quality with image-guided surgery and conventional three-step manual marking

PubMed Central

Titiyal, Jeewan S; Kaur, Manpreet; Jose, Cijin P; Falera, Ruchita; Kinkar, Ashutosh; Bageshwar, Lalit MS

2018-01-01

Purpose To compare toric intraocular lens (IOL) alignment assisted by image-guided surgery or manual marking methods and its impact on visual quality. Patients and methods This prospective comparative study enrolled 80 eyes with cataract and astigmatism ≥1.5 D to undergo phacoemulsification with toric IOL alignment by manual marking method using bubble marker (group I, n=40) or Callisto eye and Z align (group II, n=40). Postoperatively, accuracy of alignment and visual quality was assessed with a ray tracing aberrometer. Primary outcome measure was deviation from the target axis of implantation. Secondary outcome measures were visual quality and acuity. Follow-up was performed on postoperative days (PODs) 1 and 30. Results Deviation from the target axis of implantation was significantly less in group II on PODs 1 and 30 (group I: 5.5°±3.3°, group II: 3.6°±2.6°; p=0.005). Postoperative refractive cylinder was −0.89±0.35 D in group I and −0.64±0.36 D in group II (p=0.003). Visual acuity was comparable between both the groups. Visual quality measured in terms of Strehl ratio (p<0.05) and modulation transfer function (MTF) (p<0.05) was significantly better in the image-guided surgery group. Significant negative correlation was observed between deviation from target axis and visual quality parameters (Strehl ratio and MTF) (p<0.05). Conclusion Image-guided surgery allows precise alignment of toric IOL without need for reference marking. It is associated with superior visual quality which correlates with the precision of IOL alignment. PMID:29731603

SU-E-I-33: Initial Evaluation of Model-Based Iterative CT Reconstruction Using Standard Image Quality Phantoms

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

Gingold, E; Dave, J

2014-06-01

Purpose: The purpose of this study was to compare a new model-based iterative reconstruction with existing reconstruction methods (filtered backprojection and basic iterative reconstruction) using quantitative analysis of standard image quality phantom images. Methods: An ACR accreditation phantom (Gammex 464) and a CATPHAN600 phantom were scanned using 3 routine clinical acquisition protocols (adult axial brain, adult abdomen, and pediatric abdomen) on a Philips iCT system. Each scan was acquired using default conditions and 75%, 50% and 25% dose levels. Images were reconstructed using standard filtered backprojection (FBP), conventional iterative reconstruction (iDose4) and a prototype model-based iterative reconstruction (IMR). Phantom measurementsmore » included CT number accuracy, contrast to noise ratio (CNR), modulation transfer function (MTF), low contrast detectability (LCD), and noise power spectrum (NPS). Results: The choice of reconstruction method had no effect on CT number accuracy, or MTF (p<0.01). The CNR of a 6 HU contrast target was improved by 1–67% with iDose4 relative to FBP, while IMR improved CNR by 145–367% across all protocols and dose levels. Within each scan protocol, the CNR improvement from IMR vs FBP showed a general trend of greater improvement at lower dose levels. NPS magnitude was greatest for FBP and lowest for IMR. The NPS of the IMR reconstruction showed a pronounced decrease with increasing spatial frequency, consistent with the unusual noise texture seen in IMR images. Conclusion: Iterative Model Reconstruction reduces noise and improves contrast-to-noise ratio without sacrificing spatial resolution in CT phantom images. This offers the possibility of radiation dose reduction and improved low contrast detectability compared with filtered backprojection or conventional iterative reconstruction.« less

[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.

A Physics Exploratory Experiment on Plasma Liner Formation

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Knapp, Charles E.; Kirkpatrick, Ronald C.; Siemon, Richard E.; Turchi, Peter

2002-01-01

Momentum flux for imploding a target plasma in magnetized target fusion (MTF) may be delivered by an array of plasma guns launching plasma jets that would merge to form an imploding plasma shell (liner). In this paper, we examine what would be a worthwhile experiment to do in order to explore the dynamics of merging plasma jets to form a plasma liner as a first step in establishing an experimental database for plasma-jets driven magnetized target fusion (PJETS-MTF). Using past experience in fusion energy research as a model, we envisage a four-phase program to advance the art of PJETS-MTF to fusion breakeven Q is approximately 1). The experiment (PLX (Plasma Liner Physics Exploratory Experiment)) described in this paper serves as Phase I of this four-phase program. The logic underlying the selection of the experimental parameters is presented. The experiment consists of using twelve plasma guns arranged in a circle, launching plasma jets towards the center of a vacuum chamber. The velocity of the plasma jets chosen is 200 km/s, and each jet is to carry a mass of 0.2 mg - 0.4 mg. A candidate plasma accelerator for launching these jets consists of a coaxial plasma gun of the Marshall type.

Native and engineered sensors for Ca2+ and Zn2+: lessons from calmodulin and MTF1.

PubMed

Carpenter, Margaret C; Palmer, Amy E

2017-05-09

Ca 2+ and Zn 2+ dynamics have been identified as important drivers of physiological processes. In order for these dynamics to encode function, the cell must have sensors that transduce changes in metal concentration to specific downstream actions. Here we compare and contrast the native metal sensors: calmodulin (CaM), the quintessential Ca 2+ sensor and metal-responsive transcription factor 1 (MTF1), a candidate Zn 2+ sensor. While CaM recognizes and modulates the activity of hundreds of proteins through allosteric interactions, MTF1 recognizes a single DNA motif that is distributed throughout the genome regulating the transcription of many target genes. We examine how the different inorganic chemistries of these two metal ions may shape these different mechanisms transducing metal ion concentration into changing physiologic activity. In addition to native metal sensors, scientists have engineered sensors to spy on the dynamic changes of metals in cells. The inorganic chemistry of the metals shapes the possibilities in the design strategies of engineered sensors. We examine how different strategies to tune the affinities of engineered sensors mirror the strategies nature developed to sense both Ca 2+ and Zn 2+ in cells. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Drivers and mechanisms of tree mortality in moist tropical forests.

PubMed

McDowell, Nate; Allen, Craig D; Anderson-Teixeira, Kristina; Brando, Paulo; Brienen, Roel; Chambers, Jeff; Christoffersen, Brad; Davies, Stuart; Doughty, Chris; Duque, Alvaro; Espirito-Santo, Fernando; Fisher, Rosie; Fontes, Clarissa G; Galbraith, David; Goodsman, Devin; Grossiord, Charlotte; Hartmann, Henrik; Holm, Jennifer; Johnson, Daniel J; Kassim, Abd Rahman; Keller, Michael; Koven, Charlie; Kueppers, Lara; Kumagai, Tomo'omi; Malhi, Yadvinder; McMahon, Sean M; Mencuccini, Maurizio; Meir, Patrick; Moorcroft, Paul; Muller-Landau, Helene C; Phillips, Oliver L; Powell, Thomas; Sierra, Carlos A; Sperry, John; Warren, Jeff; Xu, Chonggang; Xu, Xiangtao

2018-02-16

Tree mortality rates appear to be increasing in moist tropical forests (MTFs) with significant carbon cycle consequences. Here, we review the state of knowledge regarding MTF tree mortality, create a conceptual framework with testable hypotheses regarding the drivers, mechanisms and interactions that may underlie increasing MTF mortality rates, and identify the next steps for improved understanding and reduced prediction. Increasing mortality rates are associated with rising temperature and vapor pressure deficit, liana abundance, drought, wind events, fire and, possibly, CO 2 fertilization-induced increases in stand thinning or acceleration of trees reaching larger, more vulnerable heights. The majority of these mortality drivers may kill trees in part through carbon starvation and hydraulic failure. The relative importance of each driver is unknown. High species diversity may buffer MTFs against large-scale mortality events, but recent and expected trends in mortality drivers give reason for concern regarding increasing mortality within MTFs. Models of tropical tree mortality are advancing the representation of hydraulics, carbon and demography, but require more empirical knowledge regarding the most common drivers and their subsequent mechanisms. We outline critical datasets and model developments required to test hypotheses regarding the underlying causes of increasing MTF mortality rates, and improve prediction of future mortality under climate change. No claim to original US government works New Phytologist © 2018 New Phytologist Trust.

Imaging characteristics of different mammographic screens.

PubMed

Kuhn, H; Knüpfer, W

1992-01-01

A study of mammography systems with green-emitting screens was conducted to determine how the image quality parameters (apart from dose requirement), such as modulation transfer function (MTF) and Wiener spectrum (WS), depend on the dye content of the compound and coating weight of the screen. In addition, the contribution to total noise of the individual components, i.e., film, screen, and quantum noise, was studied. The quantities derived from MTF and WS, namely detective quantum efficiency (DQE) and noise equivalent quanta (NEQ), were also investigated in regard to their dose dependency. It can be demonstrated that the MTF of the screens becomes more favorable when the dye content is increased, while noise is not significantly affected. This suggests the use of a mammography screen capable of greater detail recognition, requiring at least double the dose of today's conventional systems with approximately 80 microGy system dose. On the other hand, the manufacture of a screen with about 60% of the dose of the conventional system is possible with very little loss in image quality. For the systems in common use today (80 microGy), quantum noise represents a considerable share of the total noise at low spatial frequencies, whereas in high spatial frequencies, the graininess of the film dominates quantum noise and screen structure.

The Brazilian wide field imaging camera (WFI) for the China/Brazil earth resources satellite: CBERS 3 and 4

NASA Astrophysics Data System (ADS)

Scaduto, L. C. N.; Carvalho, E. G.; Modugno, R. G.; Cartolano, R.; Evangelista, S. H.; Segoria, D.; Santos, A. G.; Stefani, M. A.; Castro Neto, J. C.

2017-11-01

The purpose of this paper is to present the optical system developed for the Wide Field imaging Camera - WFI that will be integrated to the CBERS 3 and 4 satellites (China Brazil Earth resources Satellite). This camera will be used for remote sensing of the Earth and it is aimed to work at an altitude of 778 km. The optical system is designed for four spectral bands covering the range of wavelengths from blue to near infrared and its field of view is +/-28.63°, which covers 866 km, with a ground resolution of 64 m at nadir. WFI has been developed through a consortium formed by Opto Electrônica S. A. and Equatorial Sistemas. In particular, we will present the optical analysis based on the Modulation Transfer Function (MTF) obtained during the Engineering Model phase (EM) and the optical tests performed to evaluate the requirements. Measurements of the optical system MTF have been performed using an interferometer at the wavelength of 632.8nm and global MTF tests (including the CCD and signal processing electronic) have been performed by using a collimator with a slit target. The obtained results showed that the performance of the optical system meets the requirements of project.

Application of Magnetized Target Fusion to High-Energy Space Propulsion

NASA Technical Reports Server (NTRS)

Thio, Y. C. F.; Schmidt, G. R.; Kirkpatrick, R. C.; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

Most fusion propulsion concepts that have been investigated in the past employ some form of inertial or magnetic confinement. Although the prospective performance of these concepts is excellent, the fusion processes on which these concepts are based still require considerable development before they can be seriously considered for actual applications. Furthermore, these processes are encumbered by the need for sophisticated plasma and power handling systems that are generally quite inefficient and have historically resulted in large, massive spacecraft designs. Here we present a comparatively new approach, Magnetized Target Fusion (MTF), which offers a nearer-term avenue for realizing the tremendous performance benefits of fusion propulsion'. The key advantage of MTF is its less demanding requirements for driver energy and power processing. Additional features include: 1) very low system masses and volumes, 2) high gain and relatively low waste heat, 3) substantial utilization of energy from product neutrons, 4) efficient, low peak-power drivers based on existing pulsed power technology, and 5) very high Isp, specific power and thrust. MTF overcomes many of the problems associated with traditional fusion techniques, thus making it particularly attractive for space applications. Isp greater than 50,000 seconds and specific powers greater than 50 kilowatts/kilogram appear feasible using relatively near-term pulse power and plasma gun technology.

Sex trade in a male-to-female transgender population: psychosocial correlates of inconsistent condom use.

PubMed

Clements-Nolle, Kristen; Guzman, Robert; Harris, Susan G

2008-03-01

Research suggests that because of economic necessity, many male-to-female (MTF) transgender individuals trade sex for money, drugs, housing, and other things they may need. To date, no studies have quantitatively assessed psychosocial correlates of condom use with this population. We conducted a cross sectional study with 190 MTF transgender individuals involved in sex trade in San Francisco, California. Multivariate logistic regression was used to determine factors independently associated with inconsistent condom use during receptive anal sex with exchange partners. About one fifth of our participants reported inconsistent condom use during receptive anal sex in the past 6 months. In the multivariate model, low self-esteem [adjusted odds ratio (AOR)=3.09; 95% confidence interval (CI) (1.28, 7.47)], a history of forced sex or rape [AOR=2.91; 95% CI (1.06, 8.01)], and use of crack-cocaine [AOR=2.59; 95% CI (1.09, 6.13)] were independently associated with inconsistent condom use. Our findings highlight an urgent need for multilevel risk reduction interventions for MTF transgender individuals involved in sex trade. Such interventions will be most effective if they address the psychosocial context of sexual risk taking by focusing on issues such as low self-esteem, sexual violence, and illicit drug use.

Development of Field-Reversed Configuration Plasma Gun Formation Techniques for Magnetized Target Fusion

NASA Astrophysics Data System (ADS)

Lynn, Alan; Gilmore, Mark; Wynkoop, Tyler; Intrator, Thomas; Weber, Thomas

2012-10-01

Magnetized Target Fusion (MTF) is an innovative approach for a relatively fast and cheap path to the production of fusion energy that utilizes magnetic confinement to assist in the compression of a hot plasma to thermonuclear conditions by an external driver. Los Alamos National Laboratory (LANL) is currently pursing demonstration of the MTF concept via compression of an FRC (field-reversed configuration) plasma by a metal liner z-pinch in conjunction with the Air Force Research Laboratory in Albuquerque, NM. A key physics issue for the FRC as an MTF target lies in the initial pre-ionization (PI) stage. The PI formation process determines the amount of magnetic flux that can be trapped to form the FRC. This trapped flux plays an important role in the FRC's final equilibrium, transport, and stability properties. It also provides the route to greatest potential gains in FRC lifetime, which is essential to provide enough time to translate and compress the FRC effectively. In conjunction with LANL we plan to test and characterize a new system to improve the initial PI plasma formation. This system will use an array of plasma guns to form the initial plasma. Initial characterization of the plasma gun behavior will be presented.

Physics considerations in MV-CBCT multi-layer imager design.

PubMed

Hu, Yue-Houng; Fueglistaller, Rony; Myronakis, Marios E; Rottmann, Joerg; Wang, Adam; Shedlock, Daniel; Morf, Daniel; Baturin, Paul; Huber, Pascal; Star-Lack, Josh M; Berbeco, Ross I

2018-05-30

Megavoltage (MV) cone-beam computed tomography (CBCT) using an electronic portal imaging (EPID) offers advantageous features, including 3D mapping, treatment beam registration, high-z artifact suppression, and direct radiation dose calculation. Adoption has been slowed by image quality limitations and concerns about imaging dose. Developments in imager design, including pixelated scintillators, structured phosphors, inexpensive scintillation materials, and multi-layer imager (MLI) architecture have been explored to improve EPID image quality and reduce imaging dose. The present study employs a hybrid Monte Carlo and linear systems model to determine the effect of detector design elements, such as multi-layer architecture and scintillation materials. We follow metrics of image quality including modulation transfer function (MTF) and noise power spectrum (NPS) from projection images to 3D reconstructions to in-plane slices and apply a task based figure-of-merit, the ideal observer signal-to-noise ratio (d') to determine the effect of detector design on object detectability. Generally, detectability was limited by detector noise performance. Deploying an MLI imager with a single scintillation material for all layers yields improvement in noise performance and d' linear with the number of layers. In general, improving x-ray absorption using thicker scintillators results in improved DQE(0). However, if light yield is low, performance will be affected by electronic noise at relatively high doses, resulting in rapid image quality degradation. Maximizing image quality in a heterogenous MLI detector (i.e. multiple different scintillation materials) is most affected by limiting imager noise. However, while a second-order effect, maximizing total spatial resolution of the MLI detector is a balance between the intensity contribution of each layer against its individual MTF. So, while a thinner scintillator may yield a maximal individual-layer MTF, its quantum efficiency will be relatively low in comparison to a thicker scintillator and thus, intensity contribution may be insufficient to noticeably improve the total detector MTF. © 2018 Institute of Physics and Engineering in Medicine.

A polymorphism of the CYP17 gene related to sex steroid metabolism is associated with female-to-male but not male-to-female transsexualism.

PubMed

Bentz, Eva-Katrin; Hefler, Lukas A; Kaufmann, Ulrike; Huber, Johannes C; Kolbus, Andrea; Tempfer, Clemens B

2008-07-01

To assess the association between transsexualism and allele and genotype frequencies of the common cytochrome P450 (CYP) 17 -34 T>C single nucleotide polymorphism (SNP). Case-control study. Academic research institution. 102 male-to-female (MtF) and 49 female-to-male (FtM) transsexuals, 756 male controls, and 915 female controls. Buccal swabs and multiplex polymerase chain reaction on a microarray system. Analysis of the CYP17 -34 T>C SNP. CYP17 -34 T>C SNP allele frequencies were statistically significantly different between FtM transsexuals and female controls (CYP17 T: 55/98 [56%] and CYP17 C: 43/98 [44%] versus CYP17 T: 1253/1826 [69%] and CYP17 C: 573/1826 [31%], respectively). In accordance, genotype distributions were also different between FtM transsexuals and female controls using a recessive genotype model (CYP17 T/T+T/C: 39/49 [80%] and C/C 10/49 [20%] vs. CYP17 T/T+T/C: 821/913 [90%] and C/C 92/913 [10%], respectively). The CYP17 -34 T>C allele and genotype distributions were not statistically significantly different between MtF transsexuals and male controls. Of note, the CYP17 -34 T>C allele distribution was gender-specific among controls (CYP17 C: males; 604 of 1512 [40%] vs. females; 573 of 1826 [31%]). The MtF transsexuals had an allele distribution equivalent to male controls, whereas FtM transsexuals did not follow the gender-specific allele distribution of female controls but rather had an allele distribution equivalent to MtF transsexuals and male controls. These data support CYP17 as a candidate gene of FtM transsexualism and indicate that loss of a female-specific CYP17 T -34C allele distribution pattern is associated with FtM transsexualism.

Retrospective analysis of a detector fault for a full field digital mammography system

NASA Astrophysics Data System (ADS)

Marshall, N. W.

2006-11-01

This paper describes objective and subjective image quality measurements acquired as part of a routine quality assurance (QA) programme for an amorphous selenium (a-Se) full field digital mammography (FFDM) system between August-04 and February-05. During this period, the FFDM detector developed a fault and was replaced. A retrospective analysis of objective image quality parameters (modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE)) is presented to try and gain a deeper understanding of the detector problem that occurred. These measurements are discussed in conjunction with routine contrast-detail (c-d) results acquired with the CDMAM (Artinis, The Netherlands) test object. There was significant reduction in MTF over this period of time indicating an increase in blurring occurring within the a-Se converter layer. This blurring was not isotropic, being greater in the data line direction (left to right across the detector) than in the gate line direction (chest wall to nipple). The initial value of the 50% MTF point was 6 mm-1; for the faulty detector the 50% MTF points occurred at 3.4 mm-1 and 1.0 mm-1 in the gate line and data line directions, respectively. Prior to NNPS estimation, variance images were formed of the detector flat field images. Spatial distribution of variance was not uniform, suggesting that the physical blurring process was not constant across the detector. This change in variance with image position implied that the stationarity of the noise statistics within the image was limited and that care would be needed when performing objective measurements. The NNPS measurements confirmed the results found for the MTF, with a strong reduction in NNPS as a function of spatial frequency. This reduction was far more severe in the data line direction. A somewhat tentative DQE estimate was made; in the gate line direction there was little change in DQE up to 2.5 mm-1 but at the Nyquist frequency the DQE had fallen to approximately 35% of the original value. There was severe attenuation of DQE in the data line direction, the DQE falling to less than 0.01 above approximately 3.0 mm-1. C-d results showed an increase in threshold contrast of approximately 25% for details less than 0.2 mm in diameter, while no reduction in c-d performance was found at the largest detail diameters (1.0 mm and above). Despite the detector fault, the c-d curve was found to pass the European protocol acceptable c-d curve.

Cascaded systems analysis of photon counting detectors.

PubMed

Xu, J; Zbijewski, W; Gang, G; Stayman, J W; Taguchi, K; Lundqvist, M; Fredenberg, E; Carrino, J A; Siewerdsen, J H

2014-10-01

Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1-7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f50 (spatial-frequency at which the MTF falls to a value of 0.50) by ∼30% with corresponding improvement in DQE. The range in exposure and additive noise for which PCDs yield intrinsically higher DQE was quantified, showing performance advantages under conditions of very low-dose, high additive noise, and high fidelity rejection of coincident photons. The model for PCD signal and noise performance agreed with measurements of detector signal, MTF, and NPS and provided a useful basis for understanding complex dependencies in PCD imaging performance and the potential advantages (and disadvantages) in comparison to EIDs as well as an important guide to task-based optimization in developing new PCD imaging systems.

Objective measurement of the optical image quality in the human eye

NASA Astrophysics Data System (ADS)

Navarro, Rafael M.

2001-05-01

This communication reviews some recent studies on the optical performance of the human eye. Although the retinal image cannot be recorded directly, different objective methods have been developed, which permit to determine optical quality parameters, such as the Point Spread Function (PSF), the Modulation Transfer Function (MTF), the geometrical ray aberrations or the wavefront distortions, in the living human eye. These methods have been applied in both basic and applied research. This includes the measurement of the optical performance of the eye across visual field, the optical quality of eyes with intraocular lens implants, the aberrations induced by LASIK refractive surgery, or the manufacture of customized phase plates to compensate the wavefront aberration in the eye.

Plasma Liner Development for MTF Applications: A Status Report

NASA Technical Reports Server (NTRS)

Eskridge, R. E.; Thio, Y. F.; Lee, M.; Martin, A.; Smith, J. W.; Griffin, S. T.; Schafer, Charles (Technical Monitor)

2001-01-01

An experimental plasma gun for Magnetic Target Fusion (MTF) applications under development at the NASA Marshall Space Flight Center is described. This gun has been tested experimentally and plasma jet velocities of approximately 50 km/sec have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter has been characterized and future work for second generation "ultra-low jitter" gun development is identified.

Influence of local inhomogeneities induced in corneal ablation on the evolution of contrast sensitivity

NASA Astrophysics Data System (ADS)

Ortiz, Dolores; Saiz, Jose M.; González, Francisco

2004-04-01

The presence of local inhomogeneities in corneal tissue after refractive surgery has an influence on visual performance. Here we focus on the corneal ablation associated with Lasik surgery and its effect on the modulation transfer function (MTF) that we obtained by modifying a personalized Kooijman model. Inhomogeneities induced by the ablation occur in the form of Gaussian-distributed refractive-index variations of a given correlation length. We show how variation of refractive-index deviation and correlation length (size) of the inhomogeneities allows us to obtain pairs of values that are able to achieve a MTF evolution similar to that observed for contrast sensitivity in the same patients. An estimate of the characteristics of the local effects is obtained.

LANDSAT-4 Thematic Mapper Modulation Transfer Function (MTF) evaluation

NASA Technical Reports Server (NTRS)

Schowengerdt, R. (Principal Investigator)

1985-01-01

The Modulation Transfer Function (MTF) for thematic mapping (TM) bands 3, 4, 5 and 7 is reliably estimated with the San Mateo Bridge target in the 12/31/82 scene. These results are to be compared with those from the 8/12/83 scene. Bands 1, 2 and 6 are to be analyzed with a different target possessing greater contrast. This may be possible with the underflight data comparison currently underway. The registration of this data to the TM image of 8/12/83 for a region arround the Stockton sewage pond east of San Francisco has begun. This particular approach has the advantage that the full two-dimensional MFT will be measured instead of the MFT in only one azimuth as reported.

Optical design of laser zoom projective lens with variable total track

NASA Astrophysics Data System (ADS)

He, Yulan; Xiao, Xiangguo; Lu, Feng; Li, Yuan; Han, Kunye; Wang, Nanxi; Qiang, Hua

2017-02-01

In order to project the laser command information to the proper distance , so a laser zoom projective lens with variable total track optical system is designed in the carrier-based aircraft landing system. By choosing the zoom structure, designing of initial structure with PW solution, correcting and balancing the aberration, a large variable total track with 35 × zoom is carried out. The size of image is invariable that is φ25m, the distance of projective image is variable from 100m to 3500m. Optical reverse design, the spot is less than 8μm, the MTF is near the diffraction limitation, the value of MTF is bigger than 0.4 at 50lp/mm.

Security camera resolution measurements: Horizontal TV lines versus modulation transfer function measurements.

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

Birch, Gabriel Carisle; Griffin, John Clark

2015-01-01

The horizontal television lines (HTVL) metric has been the primary quantity used by division 6000 related to camera resolution for high consequence security systems. This document shows HTVL measurements are fundamen- tally insufficient as a metric to determine camera resolution, and propose a quantitative, standards based methodology by measuring the camera system modulation transfer function (MTF), the most common and accepted metric of res- olution in the optical science community. Because HTVL calculations are easily misinterpreted or poorly defined, we present several scenarios in which HTVL is frequently reported, and discuss their problems. The MTF metric is discussed, and scenariosmore » are presented with calculations showing the application of such a metric.« less

A calibration method for fringe reflection technique based on the analytical phase-slope description

NASA Astrophysics Data System (ADS)

Wu, Yuxiang; Yue, Huimin; Pan, Zhipeng; Liu, Yong

2018-05-01

The fringe reflection technique (FRT) has been one of the most popular methods to measure the shape of specular surface these years. The existing system calibration methods of FRT usually contain two parts, which are camera calibration and geometric calibration. In geometric calibration, the liquid crystal display (LCD) screen position calibration is one of the most difficult steps among all the calibration procedures, and its accuracy is affected by the factors such as the imaging aberration, the plane mirror flatness, and LCD screen pixel size accuracy. In this paper, based on the deduction of FRT analytical phase-slope description, we present a novel calibration method with no requirement to calibrate the position of LCD screen. On the other hand, the system can be arbitrarily arranged, and the imaging system can either be telecentric or non-telecentric. In our experiment of measuring the 5000mm radius sphere mirror, the proposed calibration method achieves 2.5 times smaller measurement error than the geometric calibration method. In the wafer surface measuring experiment, the measurement result with the proposed calibration method is closer to the interferometer result than the geometric calibration method.

Effective DQE (eDQE) for monoscopic and stereoscopic chest radiography imaging systems with the incorporation of anatomical noise.

PubMed

Boyce, Sarah J; Choudhury, Kingshuk Roy; Samei, Ehsan

2013-09-01

Stereoscopic chest biplane correlation imaging (stereo∕BCI) has been proposed as an alternative modality to single view chest x-ray (CXR). The metrics effective modulation transfer function (eMTF), effective normalized noise power spectrum (eNNPS), and effective detective quantum efficiency (eDQE) have been proposed as clinically relevant metrics for assessing clinical system performance taking into consideration the magnification and scatter effects. This study compared the metrics eMTF, eNNPS, eDQE, and detectability index for stereo∕BCI and single view CXR under isodose conditions at two magnifications for two anthropomorphic phantoms of differing sizes. Measurements for the eMTF were taken for two phantom sizes with an opaque edge test device using established techniques. The eNNPS was measured at two isodose conditions for two phantoms using established techniques. The scatter was measured for two phantoms using an established beam stop method. All measurements were also taken at two different magnifications with two phantoms. A geometrical phantom was used for comparison with prior results for CXR although the results for an anatomy free phantom are not expected to vary for BCI. Stereo∕BCI resulted in improved metrics compared to single view CXR. Results indicated that magnification can potentially improve the detection performance primarily due to the air gap which reduced scatter by ∼20%. For both phantoms, at isodose, eDQE(0) for stereo∕BCI was ∼100 times higher than that for CXR. Magnification at isodose improved eDQE(0) by ∼10 times for stereo∕BCI. Increasing the dose did not improve eDQE. The detectability index for stereo∕BCI was ∼100 times better than single view CXR for all conditions. The detectability index was also not improved with increased dose. The findings indicate that stereo∕BCI with magnification may improve detectability of subtle lung nodules compared to single view CXR. Results were improved with magnification for the smaller phantom but not for the larger phantom. The effective DQE and the detectability index did not improve with increasing dose.

SU-E-I-51: Quantitative Assessment of X-Ray Imaging Detector Performance in a Clinical Setting - a Simple Approach Using a Commercial Instrument

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

Sjoeberg, J; Bujila, R; Omar, A

2015-06-15

Purpose: To measure and compare the performance of X-ray imaging detectors in a clinical setting using a dedicated instrument for the quantitative determination of detector performance. Methods: The DQEPro (DQE Instruments Inc., London, Ontario Canada) was used to determine the MTF, NPS and DQE using an IEC compliant methodology for three different imaging modalities: conventional radiography (CsI-based detector), general-purpose radioscopy (CsI-based detector), and mammography (a-Se based detector). The radiation qualities (IEC) RQA-5 and RQA-M-2 were used for the CsI-based and a-Se-based detectors, respectively. The DQEPro alleviates some of the difficulties associated with DQE measurements by automatically positioning test devices overmore » the detector, guiding the user through the image acquisition process and providing software for calculations. Results: A comparison of the NPS showed that the image noise of the a-Se detector was less correlated than the CsI detectors. A consistently higher performance was observed for the a-Se detector at all spatial frequencies (MTF: 0.97@0.25 cy/mm, DQE: 0.72@0.25 cy/mm) and the DQE drops off slower than for the CsI detectors. The CsI detector used for conventional radiography displayed a higher performance at low spatial frequencies compared to the CsI detector used for radioscopy (DQE: 0.65 vs 0.60@0.25 cy/mm). However, at spatial frequencies above 1.3 cy/mm, the radioscopy detector displayed better performance than the conventional radiography detector (DQE: 0.35 vs 0.24@2.00 cy/mm). Conclusion: The difference in the MTF, NPS and DQE that was observed for the two different CsI detectors and the a-Se detector reflect the imaging tasks that the different detector types are intended for. The DQEPro has made the determination and calculation of quantitative metrics of X-ray imaging detector performance substantially more convenient and accessible to undertake in a clinical setting.« less

Automated optical testing of LWIR objective lenses using focal plane array sensors

NASA Astrophysics Data System (ADS)

Winters, Daniel; Erichsen, Patrik; Domagalski, Christian; Peter, Frank; Heinisch, Josef; Dumitrescu, Eugen

2012-10-01

The image quality of today's state-of-the-art IR objective lenses is constantly improving while at the same time the market for thermography and vision grows strongly. Because of increasing demands on the quality of IR optics and increasing production volumes, the standards for image quality testing increase and tests need to be performed in shorter time. Most high-precision MTF testing equipment for the IR spectral bands in use today relies on the scanning slit method that scans a 1D detector over a pattern in the image generated by the lens under test, followed by image analysis to extract performance parameters. The disadvantages of this approach are that it is relatively slow, it requires highly trained operators for aligning the sample and the number of parameters that can be extracted is limited. In this paper we present lessons learned from the R and D process on using focal plane array (FPA) sensors for testing of long-wave IR (LWIR, 8-12 m) optics. Factors that need to be taken into account when switching from scanning slit to FPAs are e.g.: the thermal background from the environment, the low scene contrast in the LWIR, the need for advanced image processing algorithms to pre-process camera images for analysis and camera artifacts. Finally, we discuss 2 measurement systems for LWIR lens characterization that we recently developed with different target applications: 1) A fully automated system suitable for production testing and metrology that uses uncooled microbolometer cameras to automatically measure MTF (on-axis and at several o-axis positions) and parameters like EFL, FFL, autofocus curves, image plane tilt, etc. for LWIR objectives with an EFL between 1 and 12mm. The measurement cycle time for one sample is typically between 6 and 8s. 2) A high-precision research-grade system using again an uncooled LWIR camera as detector, that is very simple to align and operate. A wide range of lens parameters (MTF, EFL, astigmatism, distortion, etc.) can be easily and accurately measured with this system.

WE-G-204-03: Photon-Counting Hexagonal Pixel Array CdTe Detector: Optimal Resampling to Square Pixels

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

Shrestha, S; Vedantham, S; Karellas, A

Purpose: Detectors with hexagonal pixels require resampling to square pixels for distortion-free display of acquired images. In this work, the presampling modulation transfer function (MTF) of a hexagonal pixel array photon-counting CdTe detector for region-of-interest fluoroscopy was measured and the optimal square pixel size for resampling was determined. Methods: A 0.65mm thick CdTe Schottky sensor capable of concurrently acquiring up to 3 energy-windowed images was operated in a single energy-window mode to include ≥10 KeV photons. The detector had hexagonal pixels with apothem of 30 microns resulting in pixel spacing of 60 and 51.96 microns along the two orthogonal directions.more » Images of a tungsten edge test device acquired under IEC RQA5 conditions were double Hough transformed to identify the edge and numerically differentiated. The presampling MTF was determined from the finely sampled line spread function that accounted for the hexagonal sampling. The optimal square pixel size was determined in two ways; the square pixel size for which the aperture function evaluated at the Nyquist frequencies along the two orthogonal directions matched that from the hexagonal pixel aperture functions, and the square pixel size for which the mean absolute difference between the square and hexagonal aperture functions was minimized over all frequencies up to the Nyquist limit. Results: Evaluation of the aperture functions over the entire frequency range resulted in square pixel size of 53 microns with less than 2% difference from the hexagonal pixel. Evaluation of the aperture functions at Nyquist frequencies alone resulted in 54 microns square pixels. For the photon-counting CdTe detector and after resampling to 53 microns square pixels using quadratic interpolation, the presampling MTF at Nyquist frequency of 9.434 cycles/mm along the two directions were 0.501 and 0.507. Conclusion: Hexagonal pixel array photon-counting CdTe detector after resampling to square pixels provides high-resolution imaging suitable for fluoroscopy.« less

WE-FG-207B-11: Objective Image Characterization of Spectral CT with a Dual-Layer Detector

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

Ozguner, O; Halliburton, S; Dhanantwari, A

2016-06-15

Purpose: To obtain objective reference data for the spectral performance on a dual-layer detector CT platform (IQon, Philips) and compare virtual monoenergetic to conventional CT images. Methods: Scanning was performed using the hospital’s clinical adult body protocol: helical acquisition at 120kVp, with CTDIvol=15mGy. Multiple modules (591, 515, 528) of a CATPHAN 600 phantom and a 20 cm diameter cylindrical water phantom were scanned. No modifications to the standard protocol were necessary to enable spectral imaging. Both conventional and virtual monoenergetic images were generated from acquired data. Noise characteristics were assessed through Noise Power Spectra (NPS) and pixel standard deviation frommore » water phantom images. Spatial resolution was evaluated using Modulation Transfer Functions (MTF) of a tungsten wire as well as resolution bars. Low-contrast detectability was studied using contrast-to-noise ratio (CNR) of a low contrast object. Results: MTF curves of monoenergetic and conventional images were almost identical. MTF 50%, 10%, and 5% levels for monoenergetic images agreed with conventional images within 0.05lp/cm. These observations were verified by the resolution bars, which were clearly resolved at 7lp/cm but started blurring at 8lp/cm for this protocol in both conventional and 70 keV images. NPS curves indicated that, compared to conventional images, the noise power distribution of 70 keV monoenergetic images is similar (i.e. noise texture is similar) but exhibit a low frequency peak at keVs higher and lower than 70 keV. Standard deviation measurements show monoenergetic images have lower noise except at 40 keV where it is slightly higher. CNR of monoenergetic images is mostly flat across keV values and is superior to that of conventional images. Conclusion: Values for standard image quality metrics are the same or better for monoenergetic images compared to conventional images. Results indicate virtual monoenergetic images can be used without any loss in image quality or noise penalties relative to conventional images. This study was performed as part of a research agreement among Philips Healthcare, University Hospitals of Cleveland, and Case Western Reserve University.« less

Calibration method for a large-scale structured light measurement system.

PubMed

Wang, Peng; Wang, Jianmei; Xu, Jing; Guan, Yong; Zhang, Guanglie; Chen, Ken

2017-05-10

The structured light method is an effective non-contact measurement approach. The calibration greatly affects the measurement precision of structured light systems. To construct a large-scale structured light system with high accuracy, a large-scale and precise calibration gauge is always required, which leads to an increased cost. To this end, in this paper, a calibration method with a planar mirror is proposed to reduce the calibration gauge size and cost. An out-of-focus camera calibration method is also proposed to overcome the defocusing problem caused by the shortened distance during the calibration procedure. The experimental results verify the accuracy of the proposed calibration method.

Automated assembly of camera modules using active alignment with up to six degrees of freedom

NASA Astrophysics Data System (ADS)

Bräuniger, K.; Stickler, D.; Winters, D.; Volmer, C.; Jahn, M.; Krey, S.

2014-03-01

With the upcoming Ultra High Definition (UHD) cameras, the accurate alignment of optical systems with respect to the UHD image sensor becomes increasingly important. Even with a perfect objective lens, the image quality will deteriorate when it is poorly aligned to the sensor. For evaluating the imaging quality the Modulation Transfer Function (MTF) is used as the most accepted test. In the first part it is described how the alignment errors that lead to a low imaging quality can be measured. Collimators with crosshair at defined field positions or a test chart are used as object generators for infinite-finite or respectively finite-finite conjugation. The process how to align the image sensor accurately to the optical system will be described. The focus position, shift, tilt and rotation of the image sensor are automatically corrected to obtain an optimized MTF for all field positions including the center. The software algorithm to grab images, calculate the MTF and adjust the image sensor in six degrees of freedom within less than 30 seconds per UHD camera module is described. The resulting accuracy of the image sensor rotation is better than 2 arcmin and the accuracy position alignment in x,y,z is better 2 μm. Finally, the process of gluing and UV-curing is described and how it is managed in the integrated process.

Airborne Camera System for Real-Time Applications - Support of a National Civil Protection Exercise

NASA Astrophysics Data System (ADS)

Gstaiger, V.; Romer, H.; Rosenbaum, D.; Henkel, F.

2015-04-01

In the VABENE++ project of the German Aerospace Center (DLR), powerful tools are being developed to aid public authorities and organizations with security responsibilities as well as traffic authorities when dealing with disasters and large public events. One focus lies on the acquisition of high resolution aerial imagery, its fully automatic processing, analysis and near real-time provision to decision makers in emergency situations. For this purpose a camera system was developed to be operated from a helicopter with light-weight processing units and microwave link for fast data transfer. In order to meet end-users' requirements DLR works close together with the German Federal Office of Civil Protection and Disaster Assistance (BBK) within this project. One task of BBK is to establish, maintain and train the German Medical Task Force (MTF), which gets deployed nationwide in case of large-scale disasters. In October 2014, several units of the MTF were deployed for the first time in the framework of a national civil protection exercise in Brandenburg. The VABENE++ team joined the exercise and provided near real-time aerial imagery, videos and derived traffic information to support the direction of the MTF and to identify needs for further improvements and developments. In this contribution the authors introduce the new airborne camera system together with its near real-time processing components and share experiences gained during the national civil protection exercise.

The partial coherence modulation transfer function in testing lithography lens

NASA Astrophysics Data System (ADS)

Huang, Jiun-Woei

2018-03-01

Due to the lithography demanding high performance in projection of semiconductor mask to wafer, the lens has to be almost free in spherical and coma aberration, thus, in situ optical testing for diagnosis of lens performance has to be established to verify the performance and to provide the suggesting for further improvement of the lens, before the lens has been build and integrated with light source. The measurement of modulation transfer function of critical dimension (CD) is main performance parameter to evaluate the line width of semiconductor platform fabricating ability for the smallest line width of producing tiny integrated circuits. Although the modulation transfer function (MTF) has been popularly used to evaluation the optical system, but in lithography, the contrast of each line-pair is in one dimension or two dimensions, analytically, while the lens stand along in the test bench integrated with the light source coherent or near coherent for the small dimension near the optical diffraction limit, the MTF is not only contributed by the lens, also by illumination of platform. In the study, the partial coherence modulation transfer function (PCMTF) for testing a lithography lens is suggested by measuring MTF in the high spatial frequency of in situ lithography lens, blended with the illumination of partial and in coherent light source. PCMTF can be one of measurement to evaluate the imperfect lens of lithography lens for further improvement in lens performance.

[Is Sexual Identity Optional? A Study of The Genetics of Transsexuality].

PubMed

Fernández García, Rosa M; Pásaro Méndez, Eduardo

2017-01-01

Transsexualism in the ICD-10 (International Classification of Diseases, Tenth Revision), Gender Dysphoria in adolescents and adults in the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition), is characterized by a marked incongruence between one's experienced gender and biological sex. The etiology is complex, but some hypotheses suggest that Gender Dysphoria (GD) arises from discrepant cerebral and biological sexual differentiation. Increasing evidence supports the idea of genetic vulnerability. Henningsson et al, (2004) found significant differences when they examined estrogen receptor β (ERβ) in a male-to- female (MtF) population. They suggested that a long ERβ polymorphism is more common in MtFs. Hare et al, (2009) also examined an MtF population and found a significant association between the androgen receptor (AR) and GD. Our group analyzed the same polymorphisms and found an association between ERα, ERβ and AR in GD. Our results suggest a genetic basis of GD in MtF and FtM populations. Our data corroborate the implication of the two estrogen receptors, ERα and β, and the androgen receptor in the genetic basis of GD, and advise the importance of estrogens and androgens in cerebral masculinization. Our data also confirm that sexual identity is not optional, but is determined prenatally by the genes, although it has a very important hormonal component. Therefore, its substrate is cerebral, not ideological.

Garrison Clinical Setting Inadequate for Maintenance of Procedural Skills for Emergency Medicine Physicians: A Cross-Sectional Study.

PubMed

Schauer, Steven G; Varney, Shawn M; Cox, Kristin L

2015-01-01

Emergency medicine physicians (EPs) are often placed in far-forward, isolated areas in theater. Maintenance of their emergency intervention skills is vital to keep the medical forces deployment ready. The US Army suggests that working at a Military Treatment Facility (MTF) is sufficient to keep emergency procedural skills at a deployment-ready level. We sought to compare the volume of emergency procedures that providers reported necessary to maintain their skills with the number available in the MTF setting. EPs were surveyed to quantify the number of procedures they reported they would need to perform yearly to stay deployment-ready. We obtained procedure data for their duty stations and compared the procedure volume with the survey responses to determine if working at an MTF is sufficient to keep providers' skills deployment ready. The reported necessary average numbers per year were as follows: tube thoracostomy (5.9), intubation (11.4), cricothyrotomy (4.2), lumbar puncture (5.2), central line (10.0), focused assessment with sonography for trauma (FAST) (21.3), reductions (10.6), splints (10.5), and sedations (11.7). None of the procedure volumes at MTFs met provider requirements with the exception of FAST examinations at the only trauma center. This suggests the garrison clinical environment is inadequate for maintaining procedure skills. Further research is needed to determine modalities that will provide adequate training volume. 2015.

Distortion improvement of capsule endoscope image

NASA Astrophysics Data System (ADS)

Mang, Ou-Yang; Huang, Shih-Wei; Chen, Yung-Lin; Lin, Chu-Hsun; Lin, Tai-Yung; Kuo, Yi-Ting

2007-02-01

Distortion exists in the present capsule endoscope image resulting from the confined space and the wide-angle requirement [8]. Based on the previous two lens works, the optimal design had obtained that the field of view was about 86 degrees , and MTF was about 18% at 100 lp/mm, but distortion would go to -26%. It's difficult to add another lens on the 7mm optical path between the dome and imaging lenses for improving distortion. In order to overcome this problem, we intend to design the optical dome as another optical lens. The original dome is transparent and has an equal thickness, namely without refracting light almost. Our objective in this paper is to design the inner curvature of the dome and associate two aspheric imaging lenses in front of the CMOS sensors to advance the distortion with maintaining field of view and MTF under the same capsule volume. Furthermore, the paper proposes the real object plane of intestine is nearly a curved surface rather than an ideal flat surface. Taking those reasons under consideration, we design three imaging lenses with curved object plane and obtain the field of view is about 86 degrees , MTF is about 26% at 100 lp/mm, and the distortion improve to -7.5%. Adding the dome lens is not only to enhance the image quality, but also to maintain the tiny volume requirement.

Ocular Chromatic Aberrations and Their Effects on Polychromatic Retinal Image Quality

NASA Astrophysics Data System (ADS)

Zhang, Xiaoxiao

Previous studies of ocular chromatic aberrations have concentrated on chromatic difference of focus (CDF). Less is known about the chromatic difference of image position (CDP) in the peripheral retina and no experimental attempt has been made to measure the ocular chromatic difference of magnification (CDM). Consequently, theoretical modelling of human eyes is incomplete. The insufficient knowledge of ocular chromatic aberrations is partially responsible for two unsolved applied vision problems: (1) how to improve vision by correcting ocular chromatic aberration? (2) what is the impact of ocular chromatic aberration on the use of isoluminance gratings as a tool in spatial-color vision?. Using optical ray tracing methods, MTF analysis methods of image quality, and psychophysical methods, I have developed a more complete model of ocular chromatic aberrations and their effects on vision. The ocular CDM was determined psychophysically by measuring the tilt in the apparent frontal parallel plane (AFPP) induced by interocular difference in image wavelength. This experimental result was then used to verify a theoretical relationship between the ocular CDM, the ocular CDF and the entrance pupil of the eye. In the retinal image after correcting the ocular CDF with existing achromatizing methods, two forms of chromatic aberration (CDM and chromatic parallax) were examined. The CDM was predicted by theoretical ray tracing and measured with the same method used to determine ocular CDM. The chromatic parallax was predicted with a nodal ray model and measured with the two-color vernier alignment method. The influence of these two aberrations on polychromatic MTF were calculated. Using this improved model of ocular chromatic aberration, luminance artifacts in the images of isoluminance gratings were calculated. The predicted luminance artifacts were then compared with experimental data from previous investigators. The results show that: (1) A simple relationship exists between two major chromatic aberrations and the location of the pupil; (2) The ocular CDM is measurable and varies among individuals; (3) All existing methods to correct ocular chromatic aberration face another aberration, chromatic parallax, which is inherent in the methodology; (4) Ocular chromatic aberrations have the potential to contaminate psychophysical experimental results on human spatial-color vision.

Towards adaptive and integrated management paradigms to meet the challenges of water governance.

PubMed

Halbe, J; Pahl-Wostl, C; Sendzimir, J; Adamowski, J

2013-01-01

Integrated Water Resource Management (IWRM) aims at finding practical and sustainable solutions to water resource issues. Research and practice have shown that innovative methods and tools are not sufficient to implement IWRM - the concept needs to also be integrated in prevailing management paradigms and institutions. Water governance science addresses this human dimension by focusing on the analysis of regulatory processes that influence the behavior of actors in water management systems. This paper proposes a new methodology for the integrated analysis of water resources management and governance systems in order to elicit and analyze case-specific management paradigms. It builds on the Management and Transition Framework (MTF) that allows for the examination of structures and processes underlying water management and governance. The new methodology presented in this paper combines participatory modeling and analysis of the governance system by using the MTF to investigate case-specific management paradigms. The linking of participatory modeling and research on complex management and governance systems allows for the transfer of knowledge between scientific, policy, engineering and local communities. In this way, the proposed methodology facilitates assessment and implementation of transformation processes towards IWRM that require also the adoption of adaptive management principles. A case study on flood management in the Tisza River Basin in Hungary is provided to illustrate the application of the proposed methodology.

Near-field phase-change recording using a GaN laser diode

NASA Astrophysics Data System (ADS)

Kishima, Koichiro; Ichimura, Isao; Yamamoto, Kenji; Osato, Kiyoshi; Kuroda, Yuji; Iida, Atsushi; Saito, Kimihiro

2000-09-01

We developed a 1.5-Numerical-Aperture optical setup using a GaN blue-violet laser diode. We used a 1.0 mm-diameter super-hemispherical solid immersion lens, and optimized a phase-change disk structure including the cover layer by the method of MTF simulation. The disk surface was polished by tape burnishing technique. An eye-pattern of (1-7)-coded data at the linear density of 80 nm/bit was demonstrated on the phase-change disk below a 50 nm gap height, which was realized through our air-gap servo mechanism.

A projector calibration method for monocular structured light system based on digital image correlation

NASA Astrophysics Data System (ADS)

Feng, Zhixin

2018-02-01

Projector calibration is crucial for a camera-projector three-dimensional (3-D) structured light measurement system, which has one camera and one projector. In this paper, a novel projector calibration method is proposed based on digital image correlation. In the method, the projector is viewed as an inverse camera, and a plane calibration board with feature points is used to calibrate the projector. During the calibration processing, a random speckle pattern is projected onto the calibration board with different orientations to establish the correspondences between projector images and camera images. Thereby, dataset for projector calibration are generated. Then the projector can be calibrated using a well-established camera calibration algorithm. The experiment results confirm that the proposed method is accurate and reliable for projector calibration.

42 CFR 37.42 - Chest radiograph specifications-digital radiography systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... resolution, modulation transfer function (MTF), image signal-to-noise and detective quantum efficiency must... Information Object Definitions, sections: Computed Radiography Image Information Object Definition; Digital X...

Up Periscope! Designing a New Perceptual Metric for Imaging System Performance

NASA Technical Reports Server (NTRS)

Watson, Andrew B.

2016-01-01

Modern electronic imaging systems include optics, sensors, sampling, noise, processing, compression, transmission and display elements, and are viewed by the human eye. Many of these elements cannot be assessed by traditional imaging system metrics such as the MTF. More complex metrics such as NVTherm do address these elements, but do so largely through parametric adjustment of an MTF-like metric. The parameters are adjusted through subjective testing of human observers identifying specific targets in a set of standard images. We have designed a new metric that is based on a model of human visual pattern classification. In contrast to previous metrics, ours simulates the human observer identifying the standard targets. One application of this metric is to quantify performance of modern electronic periscope systems on submarines.

Management of transgenderism.

PubMed

Spack, Norman P

2013-02-06

Gender identity disorder (transgenderism) is poorly understood from both mechanistic and clinical standpoints. Awareness of the condition appears to be increasing, probably because of greater societal acceptance and available hormonal treatment. Therapeutic options include hormone and surgical treatments but may be limited by insurance coverage because costs are high. For patients seeking male-to-female (MTF) change, hormone treatment includes estrogens, finasteride, spironolactone, and gonadotropin-releasing hormone (GnRH) analogs. Surgical options include feminizing genital and facial surgery, breast augmentation, and various fat transplantations. For patients seeking a female-to-male (FTM) gender change, medical therapy includes testosterone and GnRH analogs and surgical therapy includes mammoplasty and phalloplasty. Medical therapy for both FTM and MTF can be started in early puberty, although long-term effects are not known. All patients considering treatment need counseling and medical monitoring.

Cascaded systems analysis of charge sharing in cadmium telluride photon-counting x-ray detectors.

PubMed

Tanguay, Jesse; Cunningham, Ian A

2018-05-01

Single-photon-counting (SPC) and spectroscopic x-ray detectors are under development in academic and industry laboratories for medical imaging applications. The spatial resolution of SPC and spectroscopic x-ray detectors is an important design criterion. The purpose of this article was to extend the cascaded systems approach to include a description of the spatial resolution of SPC and spectroscopic x-ray imaging detectors. A cascaded systems approach was used to model reabsorption of characteristic x rays, Coulomb repulsion, and diffusion in SPC and spectroscopic x-ray detectors. In addition to reabsorption, diffusion, and Coulomb repulsion, the model accounted for x-ray conversion to electron-hole (e-h) pairs, integration of e-h pairs in detector elements, electronic noise, and energy thresholding. The probability density function (PDF) describing the number of e-h pairs was propagated through each stage of the model and was used to derive new theoretical expressions for the large-area gain and modulation transfer function (MTF) of CdTe SPC x-ray detectors, and the energy bin sensitivity functions and MTFs of CdTe spectroscopic detectors. Theoretical predictions were compared with the results of MATLAB-based Monte Carlo (MC) simulations and published data. Comparisons were also made with the MTF of energy-integrating systems. Under general radiographic conditions, reabsorption, diffusion, and Coulomb repulsion together artificially inflate count rates by 20% to 50%. For thicker converters (e.g. 1000 μm) and larger detector elements (e.g. 500 μm pixel pitch) these processes result in modest inflation (i.e. ∼10%) in apparent count rates. Our theoretical and MC analyses predict that SPC MTFs will be degraded relative to those of energy-integrating systems for fluoroscopic, general radiographic, and CT imaging conditions. In most cases, this degradation is modest (i.e., ∼10% at the Nyquist frequency). However, for thicker converters, the SPC MTF can be degraded by up to 25% at the Nyquist frequency relative to EI systems. Additionally, unlike EI systems, the MTF of spectroscopic systems is strongly dependent on photon energy, which results in energy-bin-dependent spatial resolution in spectroscopic systems. The PDF-transfer approach to modeling signal transfer through SPC and spectroscopic x-ray imaging systems provides a framework for understanding system performance. Application of this approach demonstrated that charge sharing artificially inflates the SPC image signal and degrades the MTF of SPC and spectroscopic systems relative to energy-integrating systems. These results further motivate the need for anticharge-sharing circuits to mitigate the effects of charge sharing on SPC and spectroscopic x-ray image quality. © 2018 American Association of Physicists in Medicine.

77 FR 71176 - Proposed Collection; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-29

... appointments at an MTF when needed. TRICARE Plus enrollment will help MTFs maintain an adequate clinical case mix for Graduate Medical Education programs and support readiness-related medical skills sustainment...

Automatic multi-camera calibration for deployable positioning systems

NASA Astrophysics Data System (ADS)

Axelsson, Maria; Karlsson, Mikael; Rudner, Staffan

2012-06-01

Surveillance with automated positioning and tracking of subjects and vehicles in 3D is desired in many defence and security applications. Camera systems with stereo or multiple cameras are often used for 3D positioning. In such systems, accurate camera calibration is needed to obtain a reliable 3D position estimate. There is also a need for automated camera calibration to facilitate fast deployment of semi-mobile multi-camera 3D positioning systems. In this paper we investigate a method for automatic calibration of the extrinsic camera parameters (relative camera pose and orientation) of a multi-camera positioning system. It is based on estimation of the essential matrix between each camera pair using the 5-point method for intrinsically calibrated cameras. The method is compared to a manual calibration method using real HD video data from a field trial with a multicamera positioning system. The method is also evaluated on simulated data from a stereo camera model. The results show that the reprojection error of the automated camera calibration method is close to or smaller than the error for the manual calibration method and that the automated calibration method can replace the manual calibration.

Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications

PubMed Central

Shrestha, Suman; Karellas, Andrew; Shi, Linxi; Gounis, Matthew J.; Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo

2016-01-01

Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54 μm. After resampling to 54 μm square pixels using trilinear interpolation, the presampled MTF at Nyquist frequency of 9.26 cycles/mm was 0.29 and 0.24 along the orthogonal directions and the limiting resolution (10% MTF) occurred at approximately 12 cycles/mm. Visual analysis of a bar pattern image showed the ability to resolve close to 12 line-pairs/mm and qualitative evaluation of a neurovascular nitinol-stent showed the ability to visualize its struts at clinically relevant conditions. Conclusions: Hexagonal pixel array photon-counting CdTe detector provides high spatial resolution in single-photon counting mode. After resampling to optimal square pixel size for distortion-free display, the spatial resolution is preserved. The dual-energy capabilities of the detector could allow for artifact-free subtraction angiography and basis material decomposition. The proposed high-resolution photon-counting detector with energy-resolving capability can be of importance for several image-guided interventional procedures as well as for pediatric applications. PMID:27147324

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

Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew, E-mail: andrew.karellas@umassmed.edu

Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixelmore » pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54 μm. After resampling to 54 μm square pixels using trilinear interpolation, the presampled MTF at Nyquist frequency of 9.26 cycles/mm was 0.29 and 0.24 along the orthogonal directions and the limiting resolution (10% MTF) occurred at approximately 12 cycles/mm. Visual analysis of a bar pattern image showed the ability to resolve close to 12 line-pairs/mm and qualitative evaluation of a neurovascular nitinol-stent showed the ability to visualize its struts at clinically relevant conditions. Conclusions: Hexagonal pixel array photon-counting CdTe detector provides high spatial resolution in single-photon counting mode. After resampling to optimal square pixel size for distortion-free display, the spatial resolution is preserved. The dual-energy capabilities of the detector could allow for artifact-free subtraction angiography and basis material decomposition. The proposed high-resolution photon-counting detector with energy-resolving capability can be of importance for several image-guided interventional procedures as well as for pediatric applications.« less

Cross-sex hormonal treatment and body uneasiness in individuals with gender dysphoria.

PubMed

Fisher, Alessandra D; Castellini, Giovanni; Bandini, Elisa; Casale, Helen; Fanni, Egidia; Benni, Laura; Ferruccio, Naika; Meriggiola, Maria Cristina; Manieri, Chiara; Gualerzi, Anna; Jannini, Emmanuele; Oppo, Alessandro; Ricca, Valdo; Maggi, Mario; Rellini, Alessandra H

2014-03-01

Cross-sex hormonal treatment (CHT) used for gender dysphoria (GD) could by itself affect well-being without the use of genital surgery; however, to date, there is a paucity of studies investigating the effects of CHT alone. This study aimed to assess differences in body uneasiness and psychiatric symptoms between GD clients taking CHT and those not taking hormones (no CHT). A second aim was to assess whether length of CHT treatment and daily dose provided an explanation for levels of body uneasiness and psychiatric symptoms. A consecutive series of 125 subjects meeting the criteria for GD who not had genital reassignment surgery were considered. Subjects were asked to complete the Body Uneasiness Test (BUT) to explore different areas of body-related psychopathology and the Symptom Checklist-90 Revised (SCL-90-R) to measure psychological state. In addition, data on daily hormone dose and length of hormonal treatment (androgens, estrogens, and/or antiandrogens) were collected through an analysis of medical records. Among the male-to-female (MtF) individuals, those using CHT reported less body uneasiness compared with individuals in the no-CHT group. No significant differences were observed between CHT and no-CHT groups in the female-to-male (FtM) sample. Also, no significant differences in SCL score were observed with regard to gender (MtF vs. FtM), hormone treatment (CHT vs. no-CHT), or the interaction of these two variables. Moreover, a two-step hierarchical regression showed that cumulative dose of estradiol (daily dose of estradiol times days of treatment) and cumulative dose of androgen blockers (daily dose of androgen blockers times days of treatment) predicted BUT score even after controlling for age, gender role, cosmetic surgery, and BMI. The differences observed between MtF and FtM individuals suggest that body-related uneasiness associated with GD may be effectively diminished with the administration of CHT even without the use of genital surgery for MtF clients. A discussion is provided on the importance of controlling both length and daily dose of treatment for the most effective impact on body uneasiness. © 2013 International Society for Sexual Medicine.

Gender identity disorder and eating disorders: similarities and differences in terms of body uneasiness.

PubMed

Bandini, Elisa; Fisher, Alessandra Daphne; Castellini, Giovanni; Lo Sauro, Carolina; Lelli, Lorenzo; Meriggiola, Maria Cristina; Casale, Helen; Benni, Laura; Ferruccio, Naika; Faravelli, Carlo; Dettore, Davide; Maggi, Mario; Ricca, Valdo

2013-04-01

Subjects with gender identity disorder (GID) have been reported to be highly dissatisfied with their body, and it has been suggested that the body is their primary source of suffering. AIMS.: To evaluate quality and intensity of body uneasiness in GID subjects, comparing them with a sample of eating disorder patients and a control group. To detect similarities and differences between subgroups of GID subjects, on the basis of genotypic sex and transitional stage. Fifty male-to-female (MtF) GID (25 without and 25 with genital reassignment surgery performed), 50 female-to-male (FtM) GID (28 without and 22 with genital reassignment surgery performed), 88 eating disorder subjects (26 anorexia nervosa, 26 bulimia nervosa, and 36 binge eating disorder), and 107 healthy subjects were evaluated. Subjects were studied by means of the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, the Symptom Checklist (SCL-90), and the Body Uneasiness Test (BUT). GID and controls reported lower psychiatric comorbidity and lower SCL-90 General Severity Index (GSI) scores than eating disorder subjects. GID MtF without genital reassignment surgery showed the highest BUT values, whereas GID FtM without genital reassignment surgery and eating disorder subjects showed higher values compared with both GID MtF and FtM who underwent genital reassignment surgery and controls. Considering BUT subscales, a different pattern of body uneasiness was observed in GID and eating disorder subjects. GID MtF and FtM without genital reassignment surgery showed the highest BUT GSI/SCL-90 GSI ratio compared with all the eating disorder groups. GID and eating disorders are characterized by a severe body uneasiness, which represents the core of distress in both conditions. Different dimensions of body uneasiness seem to be involved in GID subsamples, depending on reassignment stage and genotypic sex. In eating disorder subjects body uneasiness is primarily linked to general psychopathology, whereas in GID such a relationship is lacking. © 2013 International Society for Sexual Medicine.

Real-world antidiabetic drug use and fracture risk in 12,277 patients with type 2 diabetes mellitus: a nested case-control study.

PubMed

Losada, E; Soldevila, B; Ali, M S; Martínez-Laguna, D; Nogués, X; Puig-Domingo, M; Díez-Pérez, A; Mauricio, D; Prieto-Alhambra, D

2018-06-02

We conducted a nested case-control study to study the association between antidiabetic treatments (alone or in combination) use and fracture risk among incident type 2 Diabetes mellitus patients. We found an increased risk of bone fracture with insulin therapy compared to metformin monotherapy. Patients with type 2 diabetes mellitus (T2DM) have an increased risk of fragility fractures, to which antidiabetic therapies may contribute. We aimed to characterize the risk of fracture associated with different antidiabetic treatments as usually prescribed to T2DM patients in actual practice conditions. A case-control study was nested within a cohort of incident T2DM patients registered in 2006-2012 in the Information System for Research Development in Primary Care (Catalan acronym, SIDIAP), a database which includes records for > 5.5 million patients in Catalonia (Spain). Each case (incident major osteoporotic fracture) was risk-set matched with up to five same-sex controls by calendar year of T2DM diagnosis and year of birth (± 10 years). Study exposure included previous use of all antidiabetic medications (alone or in combination), as dispensed in the 6 months before the index date, with metformin (MTF) monotherapy, the most commonly used drug, as a reference group (active comparator). Data on 12,277 T2DM patients (2049 cases and 10,228 controls) were analyzed. Insulin use was associated with increased fracture risk (adjusted OR 1.63 (95% CI 1.30-2.04)), as was the combination of MTF and sulfonylurea (SU) (adjusted OR 1.29 (1.07-1.56)), compared with MTF monotherapy. Sensitivity analyses suggest possible causality for insulin therapy but not for the MTF + SU combination association. No significant association was found with any other antidiabetic medications. Insulin monotherapy was associated with an increased fracture risk compared to MTF monotherapy in T2DM patients. Fracture risk should be taken into account when starting a glucose-lowering drug as part of T2DM treatment.

Effect of cross-sex hormone treatment on cardiovascular risk factors in transsexual individuals. Experience in a specialized unit in Catalonia.

PubMed

Quirós, Carmen; Patrascioiu, Ioana; Mora, Mireia; Aranda, Gloria Beatriz; Hanzu, Felicia Alexandra; Gómez-Gil, Esther; Godás, Teresa; Halperin, Irene

2015-05-01

Since the onset of cross hormone therapy (CHT) in transsexual individuals, there has been concern about possible chronic side effects. Our objective was to assess baseline differences in lipid profile in individuals with gender identity disorder in relation to prior CHT, and changes in the lipid profile and other cardiovascular (CV) risk factors after 24 months of treatment. Retrospective longitudinal study including all individuals assisted for the first time in the Gender Identity Unit of Catalonia from 2006 to 2010. Socio-demographical, anthropometric and laboratory data were collected. We evaluated 247 transsexuals, 150 male to female (MtF: 60.7%) and 97 female to male (FtM; 39.3%). At baseline, FtM transsexuals were younger and had started prior CHT less often than MtF (13.4% vs. 64.7%; p<0.001). During follow up, in MtF weight and BMI increased significantly, as well as systolic and diastolic blood pressure, though these latter remained within normal range. No significant differences in lipid profile were observed. FtM transsexuals also presented an increase in weight and BMI, without differences in blood pressure. A general worsening in lipid profile was observed in this group, with increased total cholesterol (166.0 ± 35.1 vs. 175.6 ± 38.2mg/dL; p=0.001), triglycerides (70.6 ± 30.7 vs. 102.3 ± 68.5 mg/dL; p<0.001) and LDL cholesterol (103.8 ± 28.7 vs. 112.8 ± 30.3 mg/dL; p=.013) and decreased HDL cholesterol (52.2 ± 12.2 vs. 45.4 ± 13.8 mg/dL; p=0.001), even though final levels were all within normal range. There is no detectable increase in CV risk factors in MtF transsexuals who were treated with currently prescribed estrogenic compounds, while a slight worsening in lipid profile takes place in the FtM group, though within normal limits. Copyright © 2014 SEEN. Published by Elsevier España, S.L.U. All rights reserved.

Relationship challenges and relationship maintenance activities following disclosure of transsexualism.

PubMed

Alegría, C Aramburu

2010-12-01

• Transsexual persons are increasing their visibility in society, and health care providers and others (such as social workers) will be called upon to help with issues that transsexual persons face. Challenges that face transsexual persons often include issues involving relationships. Psychiatric and mental health nurses and other caregivers can increase their therapeutic skills in working with couples that include transsexual persons by becoming aware of these challenges and subsequent activities that can help with them. • This research study looks at couple relationships in which one partner reveals male-to-female transsexual identity. These are relationships that were established as man-woman and now will transition into relationships that include a male-to-female person and a female partner. • Common challenges for these couples include issues related to: (1) sexual identity and relationship uncertainty; (2) male-to-female transition decision making; and (3) presenting in public. • Relationship maintenance activities that helped the couples in the study maintain and strengthen their relationships through these challenges include: (1) communication; (2) self-talk (for example, putting the situation in perspective); (3) social networks; (4) positive interactions; (5) impression management (for example, managing displays of affection in public); and (6) social activism. This qualitative study describes the relational dynamics that help sustain relationships of couples that include male-to-female transsexual persons (MTF) and their natal female partners (NF) following disclosure of transsexualism. Relationship challenges and relationship maintenance activities are identified. Each partner in 17 MTF-NF couples participated in individual surveys and interviews. The data were coded for themes related to relationship challenges and activities. MTF-NF couples experience challenges within the contexts of their relationships and of society. These challenges include: (1) sexual identity and relationship uncertainty; (2) male-to-female transition decision making; and (3) public presentation. Relationship maintenance activities enabled the study couples to maintain and strengthen their relationships through these challenges. These activities include: (1) communication; (2) self-talk; (3) social networks; (4) positivity; (5) impression management; and (6) social activism. Via this report, psychiatric and mental health nurses can increase their therapeutic skills in working with MTF-NF couples. © 2010 Blackwell Publishing.

A Novel Multi-Camera Calibration Method based on Flat Refractive Geometry

NASA Astrophysics Data System (ADS)

Huang, S.; Feng, M. C.; Zheng, T. X.; Li, F.; Wang, J. Q.; Xiao, L. F.

2018-03-01

Multi-camera calibration plays an important role in many field. In the paper, we present a novel multi-camera calibration method based on flat refractive geometry. All cameras can acquire calibration images of transparent glass calibration board (TGCB) at the same time. The application of TGCB leads to refractive phenomenon which can generate calibration error. The theory of flat refractive geometry is employed to eliminate the error. The new method can solve the refractive phenomenon of TGCB. Moreover, the bundle adjustment method is used to minimize the reprojection error and obtain optimized calibration results. Finally, the four-cameras calibration results of real data show that the mean value and standard deviation of the reprojection error of our method are 4.3411e-05 and 0.4553 pixel, respectively. The experimental results show that the proposed method is accurate and reliable.

Comparative evaluation of toric intraocular lens alignment and visual quality with image-guided surgery and conventional three-step manual marking.

PubMed

Titiyal, Jeewan S; Kaur, Manpreet; Jose, Cijin P; Falera, Ruchita; Kinkar, Ashutosh; Bageshwar, Lalit Ms

2018-01-01

To compare toric intraocular lens (IOL) alignment assisted by image-guided surgery or manual marking methods and its impact on visual quality. This prospective comparative study enrolled 80 eyes with cataract and astigmatism ≥1.5 D to undergo phacoemulsification with toric IOL alignment by manual marking method using bubble marker (group I, n=40) or Callisto eye and Z align (group II, n=40). Postoperatively, accuracy of alignment and visual quality was assessed with a ray tracing aberrometer. Primary outcome measure was deviation from the target axis of implantation. Secondary outcome measures were visual quality and acuity. Follow-up was performed on postoperative days (PODs) 1 and 30. Deviation from the target axis of implantation was significantly less in group II on PODs 1 and 30 (group I: 5.5°±3.3°, group II: 3.6°±2.6°; p =0.005). Postoperative refractive cylinder was -0.89±0.35 D in group I and -0.64±0.36 D in group II ( p =0.003). Visual acuity was comparable between both the groups. Visual quality measured in terms of Strehl ratio ( p <0.05) and modulation transfer function (MTF) ( p <0.05) was significantly better in the image-guided surgery group. Significant negative correlation was observed between deviation from target axis and visual quality parameters (Strehl ratio and MTF) ( p <0.05). Image-guided surgery allows precise alignment of toric IOL without need for reference marking. It is associated with superior visual quality which correlates with the precision of IOL alignment.

Generalized two-dimensional (2D) linear system analysis metrics (GMTF, GDQE) for digital radiography systems including the effect of focal spot, magnification, scatter, and detector characteristics.

PubMed

Jain, Amit; Kuhls-Gilcrist, Andrew T; Gupta, Sandesh K; Bednarek, Daniel R; Rudin, Stephen

2010-03-01

The MTF, NNPS, and DQE are standard linear system metrics used to characterize intrinsic detector performance. To evaluate total system performance for actual clinical conditions, generalized linear system metrics (GMTF, GNNPS and GDQE) that include the effect of the focal spot distribution, scattered radiation, and geometric unsharpness are more meaningful and appropriate. In this study, a two-dimensional (2D) generalized linear system analysis was carried out for a standard flat panel detector (FPD) (194-micron pixel pitch and 600-micron thick CsI) and a newly-developed, high-resolution, micro-angiographic fluoroscope (MAF) (35-micron pixel pitch and 300-micron thick CsI). Realistic clinical parameters and x-ray spectra were used. The 2D detector MTFs were calculated using the new Noise Response method and slanted edge method and 2D focal spot distribution measurements were done using a pin-hole assembly. The scatter fraction, generated for a uniform head equivalent phantom, was measured and the scatter MTF was simulated with a theoretical model. Different magnifications and scatter fractions were used to estimate the 2D GMTF, GNNPS and GDQE for both detectors. Results show spatial non-isotropy for the 2D generalized metrics which provide a quantitative description of the performance of the complete imaging system for both detectors. This generalized analysis demonstrated that the MAF and FPD have similar capabilities at lower spatial frequencies, but that the MAF has superior performance over the FPD at higher frequencies even when considering focal spot blurring and scatter. This 2D generalized performance analysis is a valuable tool to evaluate total system capabilities and to enable optimized design for specific imaging tasks.

Endocrine Treatment of Transsexual Persons

MedlinePlus

... describe persons who felt profound discomfort with their biological sex. Today, medical treatment, sometimes together with surgery, ... to reduce estrogens to the levels found in biological males. Male-to-female transsexual (MTF) persons Cross- ...

A method for evaluating image quality of monochrome and color displays based on luminance by use of a commercially available color digital camera

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

Tokurei, Shogo, E-mail: shogo.tokurei@gmail.com, E-mail: junjim@med.kyushu-u.ac.jp; Morishita, Junji, E-mail: shogo.tokurei@gmail.com, E-mail: junjim@med.kyushu-u.ac.jp

Purpose: The aim of this study is to propose a method for the quantitative evaluation of image quality of both monochrome and color liquid-crystal displays (LCDs) using a commercially available color digital camera. Methods: The intensities of the unprocessed red (R), green (G), and blue (B) signals of a camera vary depending on the spectral sensitivity of the image sensor used in the camera. For consistent evaluation of image quality for both monochrome and color LCDs, the unprocessed RGB signals of the camera were converted into gray scale signals that corresponded to the luminance of the LCD. Gray scale signalsmore » for the monochrome LCD were evaluated by using only the green channel signals of the camera. For the color LCD, the RGB signals of the camera were converted into gray scale signals by employing weighting factors (WFs) for each RGB channel. A line image displayed on the color LCD was simulated on the monochrome LCD by using a software application for subpixel driving in order to verify the WF-based conversion method. Furthermore, the results obtained by different types of commercially available color cameras and a photometric camera were compared to examine the consistency of the authors’ method. Finally, image quality for both the monochrome and color LCDs was assessed by measuring modulation transfer functions (MTFs) and Wiener spectra (WS). Results: The authors’ results demonstrated that the proposed method for calibrating the spectral sensitivity of the camera resulted in a consistent and reliable evaluation of the luminance of monochrome and color LCDs. The MTFs and WS showed different characteristics for the two LCD types owing to difference in the subpixel structure. The MTF in the vertical direction of the color LCD was superior to that of the monochrome LCD, although the WS in the vertical direction of the color LCD was inferior to that of the monochrome LCD as a result of luminance fluctuations in RGB subpixels. Conclusions: The authors’ method based on the use of a commercially available color camera is useful to evaluate and understand the display performances of both monochrome and color LCDs in radiology departments.« less

A calibration method of infrared LVF based spectroradiometer

NASA Astrophysics Data System (ADS)

Liu, Jiaqing; Han, Shunli; Liu, Lei; Hu, Dexin

2017-10-01

In this paper, a calibration method of LVF-based spectroradiometer is summarize, including spectral calibration and radiometric calibration. The spectral calibration process as follow: first, the relationship between stepping motor's step number and transmission wavelength is derivative by theoretical calculation, including a non-linearity correction of LVF;second, a line-to-line method was used to corrected the theoretical wavelength; Finally, the 3.39 μm and 10.69 μm laser is used for spectral calibration validation, show the sought 0.1% accuracy or better is achieved.A new sub-region multi-point calibration method is used for radiometric calibration to improving accuracy, results show the sought 1% accuracy or better is achieved.

Optics-Only Calibration of a Neural-Net Based Optical NDE Method for Structural Health Monitoring

NASA Technical Reports Server (NTRS)

Decker, Arthur J.

2004-01-01

A calibration process is presented that uses optical measurements alone to calibrate a neural-net based NDE method. The method itself detects small changes in the vibration mode shapes of structures. The optics-only calibration process confirms previous work that the sensitivity to vibration-amplitude changes can be as small as 10 nanometers. A more practical value in an NDE service laboratory is shown to be 50 nanometers. Both model-generated and experimental calibrations are demonstrated using two implementations of the calibration technique. The implementations are based on previously published demonstrations of the NDE method and an alternative calibration procedure that depends on comparing neural-net and point sensor measurements. The optics-only calibration method, unlike the alternative method, does not require modifications of the structure being tested or the creation of calibration objects. The calibration process can be used to test improvements in the NDE process and to develop a vibration-mode-independence of damagedetection sensitivity. The calibration effort was intended to support NASA s objective to promote safety in the operations of ground test facilities or aviation safety, in general, by allowing the detection of the gradual onset of structural changes and damage.

Wavelength calibration of dispersive near-infrared spectrometer using relative k-space distribution with low coherence interferometer

NASA Astrophysics Data System (ADS)

Kim, Ji-hyun; Han, Jae-Ho; Jeong, Jichai

2016-05-01

The commonly employed calibration methods for laboratory-made spectrometers have several disadvantages, including poor calibration when the number of characteristic spectral peaks is low. Therefore, we present a wavelength calibration method using relative k-space distribution with low coherence interferometer. The proposed method utilizes an interferogram with a perfect sinusoidal pattern in k-space for calibration. Zero-crossing detection extracts the k-space distribution of a spectrometer from the interferogram in the wavelength domain, and a calibration lamp provides information about absolute wavenumbers. To assign wavenumbers, wavelength-to-k-space conversion is required for the characteristic spectrum of the calibration lamp with the extracted k-space distribution. Then, the wavelength calibration is completed by inverse conversion of the k-space into wavelength domain. The calibration performance of the proposed method was demonstrated with two experimental conditions of four and eight characteristic spectral peaks. The proposed method elicited reliable calibration results in both cases, whereas the conventional method of third-order polynomial curve fitting failed to determine wavelengths in the case of four characteristic peaks. Moreover, for optical coherence tomography imaging, the proposed method could improve axial resolution due to higher suppression of sidelobes in point spread function than the conventional method. We believe that our findings can improve not only wavelength calibration accuracy but also resolution for optical coherence tomography.

Verification of the ISO calibration method for field pyranometers under tropical sky conditions

NASA Astrophysics Data System (ADS)

Janjai, Serm; Tohsing, Korntip; Pattarapanitchai, Somjet; Detkhon, Pasakorn

2017-02-01

Field pyranomters need to be annually calibrated and the International Organization for Standardization (ISO) has defined a standard method (ISO 9847) for calibrating these pyranometers. According to this standard method for outdoor calibration, the field pyranometers have to be compared to a reference pyranometer for the period of 2 to 14 days, depending on sky conditions. In this work, the ISO 9847 standard method was verified under tropical sky conditions. To verify the standard method, calibration of field pyranometers was conducted at a tropical site located in Nakhon Pathom (13.82o N, 100.04o E), Thailand under various sky conditions. The conditions of the sky were monitored by using a sky camera. The calibration results for different time periods used for the calibration under various sky conditions were analyzed. It was found that the calibration periods given by this standard method could be reduced without significant change in the final calibration result. In addition, recommendation and discussion on the use of this standard method in the tropics were also presented.

High School and Youth Trends

MedlinePlus

... High School and Youth Trends Monitoring the Future Survey: High School and Youth Trends Email Facebook Twitter ... December 2017 This year's Monitoring the Future (MTF) survey of drug use and attitudes among 8th, 10th, ...

47 CFR 87.145 - Acceptability of transmitters for licensing.

Code of Federal Regulations, 2010 CFR

2010-10-01

...., SW., Washington, DC 20591. (c) The equipment listed below is exempted from certification. The... § 87.147(e). (4) Signal generators when used as radionavigation land test stations (MTF). (d) Aircraft...

Optimization of wavefront coding imaging system using heuristic algorithms

NASA Astrophysics Data System (ADS)

González-Amador, E.; Padilla-Vivanco, A.; Toxqui-Quitl, C.; Zermeño-Loreto, O.

2017-08-01

Wavefront Coding (WFC) systems make use of an aspheric Phase-Mask (PM) and digital image processing to extend the Depth of Field (EDoF) of computational imaging systems. For years, several kinds of PM have been designed to produce a point spread function (PSF) near defocus-invariant. In this paper, the optimization of the phase deviation parameter is done by means of genetic algorithms (GAs). In this, the merit function minimizes the mean square error (MSE) between the diffraction limited Modulated Transfer Function (MTF) and the MTF of the system that is wavefront coded with different misfocus. WFC systems were simulated using the cubic, trefoil, and 4 Zernike polynomials phase-masks. Numerical results show defocus invariance aberration in all cases. Nevertheless, the best results are obtained by using the trefoil phase-mask, because the decoded image is almost free of artifacts.

A comparison of the performance of digital mammography systems.

PubMed

Monnin, P; Gutierrez, D; Bulling, S; Guntern, D; Verdun, F R

2007-03-01

An objective analysis of image quality parameters was performed for six digital mammography systems. The presampled modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) for the systems were determined at different doses, for 28 kVp with a Mo/Mo or W/Al target/filter combination and 2 mm of additional aluminium filtration. The flat-panel units have higher MTF and DQE in the mid to high frequency range than standard CR systems. The highest DQE, over the whole dose range, is for the slit-scanning direct photon counting system. Dual-side read CR can overcome the inherent x-ray absorption and signal collection limitations of standard CR mammography, improving the low-frequency DQE by 40%, to the same level as full-field systems, but it does not improve the poor spatial resolution of phosphor.

Magnetized Target Fusion Propulsion: Plasma Injectors for MTF Guns

NASA Technical Reports Server (NTRS)

Griffin, Steven T.

2003-01-01

To achieve increased payload size and decreased trip time for interplanetary travel, a low mass, high specific impulse, high thrust propulsion system is required. This suggests the need for research into fusion as a source of power and high temperature plasma. The plasma would be deflected by magnetic fields to provide thrust. Magnetized Target Fusion (MTF) research consists of several related investigations into these topics. These include the orientation and timing of the plasma guns and the convergence and interface development of the "pusher" plasma. Computer simulations of the gun as it relates to plasma initiation and repeatability are under investigation. One of the items under development is the plasma injector. This is a surface breakdown driven plasma generator designed to function at very low pressures. The performance, operating conditions and limitations of these injectors need to be determined.

WISE TF: A MID-INFRARED, 3.4 {mu}m EXTENSION OF THE TULLY-FISHER RELATION USING WISE PHOTOMETRY

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

Lagattuta, David J.; Mould, Jeremy R.; Staveley-Smith, Lister

2013-07-10

We present a mid-infrared Tully-Fisher (TF) relation using photometry from the 3.4 {mu}m W1 band of the Wide-field Infrared Survey Explorer (WISE) satellite. The WISE TF relation is formed from 568 galaxies taken from the all-sky 2MASS Tully-Fisher (2MTF) galaxy catalog, spanning a range of environments including field, group, and cluster galaxies. This constitutes the largest mid-infrared TF relation constructed to date. After applying a number of corrections to galaxy magnitudes and line widths, we measure a master TF relation given by M{sub corr} = -22.24 - 10.05[log (W{sub corr}) - 2.5], with an average dispersion of {sigma}{sub WISE} =more » 0.686 mag. There is some tension between WISE TF and a preliminary 3.6 {mu}m relation, which has a shallower slope and almost no intrinsic dispersion. However, our results agree well with a more recent relation constructed from a large sample of cluster galaxies. We additionally compare WISE TF to the near-infrared 2MTF template relations, finding a good agreement between the TF parameters and total dispersions of WISE TF and the 2MTF K-band template. This fact, coupled with typical galaxy colors of (K - W1) {approx} 0, suggests that these two bands are tracing similar stellar populations, including the older, centrally-located stars in the galactic bulge which can (for galaxies with a prominent bulge) dominate the light profile.« less

Visual outcomes after balanced salt solution infiltration during lenticule separation in small-incision lenticule extraction for myopic astigmatism.

PubMed

Liu, Ting; Zhu, Xiaomin; Chen, Kaijian; Bai, Ji

2017-07-01

To evaluate the refractive outcomes of balanced salt solution infiltration during small-incision lenticule extraction (SMILE).This randomized prospective study enrolled 52 patients (104 eyes) with myopic astigmatism. Patients underwent SMILE to correct the myopic astigmatism in Daping Hospital of the Third Military Medical University between January and July 2013. One eye of each patient received traditional SMILE (control group) and the other received a modified SMILE procedure (liquid infiltration group). The corrected distance visual acuity (CDVA), postoperative uncorrected distance visual acuity (UDVA), refraction, wavefront aberration, intraocular pressure (IOP), modulation transfer function (MTF) cut-off frequency, and objective scattering index (OSI) were evaluated.UDVA in the liquid infiltration group was significantly higher than that in the control group at 1 day postoperatively, but not at 1 month after surgery. Moreover, OSI and MTF cut-off frequency in the liquid infiltration group were higher than those in the control group at early follow-up. However, no significant intergroup difference was observed in the OSI and MTF cut-off frequency at 3 months after surgery. In addition, the predictability was better in the liquid infiltration group than in the control group. The changes of horizontal coma in the liquid infiltration group were lesser than those in the control group. However, no intergroup difference was observed in the reduction of IOP at 1 month after surgery.The modified SMILE procedure results in better visual outcomes than did the traditional SMILE procedure when used for treating myopic astigmatism.

Anti-cancer Antibody Trastuzumab-Melanotransferrin Conjugate (BT2111) for the Treatment of Metastatic HER2+ Breast Cancer Tumors in the Brain: an In-Vivo Study.

PubMed

Nounou, Mohamed Ismail; Adkins, Chris E; Rubinchik, Evelina; Terrell-Hall, Tori B; Afroz, Mohamed; Vitalis, Tim; Gabathuler, Reinhard; Tian, Mei Mei; Lockman, Paul R

2016-12-01

The ability of human melanotransferrin (hMTf) to carry a therapeutic concentration of trastuzumab (BTA) in the brain after conjugation (in the form of trastuzumab-melanotransferrin conjugate, BT2111 conjugate) was investigated by measuring the reduction of the number and size of metastatic human HER 2+ breast cancer tumors in a preclinical model of brain metastases of breast cancer. Human metastatic brain seeking breast cancer cells were injected in NuNu mice (n = 6-12 per group) which then developed experimental brain metastases. Drug uptake was analyzed in relation to metastasis size and blood-tumor barrier permeability. To investigate in-vivo activity against brain metastases, equimolar doses of the conjugate, and relevant controls (hMTf and BTA) in separate groups were administered biweekly after intracardiac injection of the metastatic cancer cells. The trastuzumab-melanotransferrin conjugate (BT2111) reduced the number of preclinical human HER 2+ breast cancer metastases in the brain by 68% compared to control groups. Tumors which remained after treatment were 46% smaller than the control groups. In contrast, BTA alone had no effect on reducing number of metastases, and was associated with only a minimal reduction in metastasis size. The results suggest the novel trastuzumab-melanotransferrin conjugate (BT2111) may have utility in treating brain metastasis and validate hMTf as a potential vector for antibody transport across the Blood Brain Barrier (BBB).

HIV-related sexual risk behaviors among male-to-female transgender people in Nepal.

PubMed

Bhatta, Dharma Nand

2014-05-01

Transgender women are a vulnerable and key risk group for HIV, and most research has shown an increased frequency of HIV infection among this minority population. This study examined the prevalence of HIV-related sexual risk behaviors and the socio-demographic correlates with HIV-related sexual risk behaviors among male-to-female (MtF) transgender persons. Data were collected from a sample of 232 individuals through venue-based and snowball sampling and face-to-face interviews. The HIV-related sexual risk behaviors among the MtF transgender persons were: sex without using a condom (48.3%; 95% confidence interval (CI) 41.8-54.8), unprotected anal sex (68.1%; 95% CI 62.0-74.2), and unprotected sex with multiple partners (88.4%; 95% CI 84.3-92.5). Statistically significant differences were found for age, income, education, alcohol habit, and sex with more than two partners per day for these three different HIV-related sexual risk behaviors. MtF transgender persons with a secondary or higher level of education were three times (OR 2.93) more likely to have unprotected sex with multiple partners compared to those with a primary level or no education. Age, education, income, frequency of daily sexual contact, and an alcohol habit remain significant with regard to HIV-related sexual risk behavior. There is an urgent need for programs and interventions to reduce risky sexual behaviors in this minority population. Copyright © 2014 The Author. Published by Elsevier Ltd.. All rights reserved.

Investigation of Spheromak Plasma Cooling through Metallic Liner Spallation during Compression

NASA Astrophysics Data System (ADS)

Ross, Keeton; Mossman, Alex; Young, William; Ivanov, Russ; O'Shea, Peter; Howard, Stephen

2016-10-01

Various magnetic-target fusion (MTF) reactor concepts involve a preliminary magnetic confinement stage, followed by a metallic liner implosion that compresses the plasma to fusion conditions. The process is repeated to produce a pulsed, net-gain energy system. General Fusion, Inc. is pursuing one scheme that involves the compression of spheromak plasmas inside a liner formed by a collapsing vortex of liquid Pb-Li. The compression is driven by focused acoustic waves launched by gas-driven piston impacts. Here we describe a project to exploring the effects of possible liner spallation during compression on the spheromaks temperature, lifetime, and stability. We employ a 1 J, 10 ns pulsed YAG laser at 532nm focused onto a thin film of Li or Al to inject a known quantity of metallic impurities into a spheromak plasma and then measure the response. Diagnostics including visible and ultraviolet spectrometers, ion Doppler, B-probes, and Thomson scattering are used for plasma characterization. We then plan to apply the trends measured under these controlled conditions to evaluate the role of wall impurities during `field shots', where spheromaks are compressed through a chemically driven implosion of an aluminum flux conserver. The hope is that with further study we could more accurately include the effect of wall impurities on the fusion yield of a reactor-scale MTF system. Experimental procedures and results are presented, along with their relation to other liner-driven, MTF schemes. -/a

Experiences of Discrimination, Harassment, and Violence in a Sample of Italian Transsexuals Who Have Undergone Sex-Reassignment Surgery.

PubMed

Prunas, Antonio; Bandini, Elisa; Fisher, Alessandra D; Maggi, Mario; Pace, Valeria; Quagliarella, Luca; Todarello, Orlando; Bini, Maurizio

2018-07-01

The present study aims to provide an overview of experiences of discrimination, harassment, and violence in a sample of Italian transsexuals who have undergone sex-reassignment surgery (SRS). Lack of support for gender transition from family members was also assessed, before and after SRS. Data were collected in the context of a multicentric study (Milan, Florence, and Bari) on SRS outcome. Patients who underwent SRS were contacted and asked to fill out a questionnaire concerning experiences of discrimination, harassment, violence, and crime they might have experienced in previous years. Seventy-two participants took part in the research: 46 were male-to-female (MtF; 64%) and 26 were female-to-male (FtM; 36%). Thirty-six percent of the total sample (with no differences between MtF and FtM) experienced at least one episode of harassment, violence, or discrimination. The workplace was reported to be the social area with the highest risk of discrimination and harassment (22% of participants). Reports of more than one incident of discrimination, harassment, and violence characterized the majority of participants in the MtF sample. Compared with previous studies carried out in other countries, a much larger proportion of participants could count on a supportive family environment before and after transition. Our results show that Italian society at large is prejudiced against transsexuals, but at a more "micro" level, having a trans person as a family member might result in a protective and tolerant attitude.

Kisspeptin Expression in the Human Infundibular Nucleus in Relation to Sex, Gender Identity, and Sexual Orientation.

PubMed

Taziaux, Melanie; Staphorsius, Annemieke S; Ghatei, Mohammad A; Bloom, Stephen R; Swaab, Dick F; Bakker, Julie

2016-06-01

Since the discovery of its central role in reproduction, our functional neuroanatomical knowledge of the hypothalamic kisspeptin system is predominantly based on animal studies. Although sex differences in kisspeptin expression have been shown in humans in adulthood, the developmental origin of this sex difference is unknown. Our objectives were to determine the following: 1) when during development the sex difference in kisspeptin expression in the infundibular nucleus would emerge and 2) whether this sex difference is related to sexual orientation or transsexuality. Postmortem hypothalamic tissues were collected by The Netherlands Brain Bank, and sections were stained for kisspeptin by immunohistochemistry. Hypothalami of 43 control subjects were categorized into three periods: infant/prepubertal (six girls, seven boys), adult (11 women, seven men), and elderly (six aged women, six aged men). Eight male-to-female (MTF) transsexuals, three HIV(+) heterosexual men, and five HIV(+) homosexual men were also analyzed. We estimated the total number of kisspeptin-immunoreactive neurons within the infundibular nucleus. Quantitative analysis confirmed that the human infundibular kisspeptin system exhibits a female-dominant sex difference. The number of kisspeptin neurons is significantly greater in the infant/prepubertal and elderly periods compared with the adult period. Finally, in MTF transsexuals, but not homosexual men, a female-typical kisspeptin expression was observed. These findings suggest that infundibular kisspeptin neurons are sensitive to circulating sex steroid hormones throughout life and that the sex reversal observed in MTF transsexuals might reflect, at least partially, an atypical brain sexual differentiation.

Physical characterization and performance comparison of active- and passive-pixel CMOS detectors for mammography.

PubMed

Elbakri, I A; McIntosh, B J; Rickey, D W

2009-03-21

We investigated the physical characteristics of two complementary metal oxide semiconductor (CMOS) mammography detectors. The detectors featured 14-bit image acquisition, 50 microm detector element (del) size and an active area of 5 cm x 5 cm. One detector was a passive-pixel sensor (PPS) with signal amplification performed by an array of amplifiers connected to dels via data lines. The other detector was an active-pixel sensor (APS) with signal amplification performed at each del. Passive-pixel designs have higher read noise due to data line capacitance, and the APS represents an attempt to improve the noise performance of this technology. We evaluated the detectors' resolution by measuring the modulation transfer function (MTF) using a tilted edge. We measured the noise power spectra (NPS) and detective quantum efficiencies (DQE) using mammographic beam conditions specified by the IEC 62220-1-2 standard. Our measurements showed the APS to have much higher gain, slightly higher MTF, and higher NPS. The MTF of both sensors approached 10% near the Nyquist limit. DQE values near dc frequency were in the range of 55-67%, with the APS sensor DQE lower than the PPS DQE for all frequencies. Our results show that lower read noise specifications in this case do not translate into gains in the imaging performance of the sensor. We postulate that the lower fill factor of the APS is a possible cause for this result.

[Social support in gender reassignment surgery].

PubMed

Hess, J; Kurth, I; Henkel, A; Panic, L; Rübben, H; Rossi Neto, R; Hess-Busch, Y

2017-02-01

Gender reassignment surgery (GRS) can lead to discrimination. This transition makes great demands on the individual and also affects the social environment. To evaluate the social support of male-to-female (MtF) transgender people. Group A comprised 254 consecutive MtF transsexuals, who received a penile inversion vaginoplasty between 2004 and 2010. These women were surveyed retrospectively. Group B comprised 144 consecutive MtF transsexuals who presented for preoperative counselling. These patients were asked to answer the survey in advance of the planned GRS. The return rate was 46.9 % (A) and 95.1 % (B). In both groups, approximately two-thirds lived with their parents or children at ease. About 13.4 % (A) and 16.9 % (B) estimated the relationship towards their parents and one- seventh (A) or one-sixth (B) woman rated their relationship towards their children as poor. The acceptance of the parents regarding GRS was 65.6 % (A) and 77.1 % (B). In total 20 % (A) and 9.2 % (B) did not, however, accept GRS in their children. The acceptance of children regarding GRS was 64.9 % (A) and 71.1 % (B) with 10.8 % (A) and 6.7 % (B) who did not approve the decision. Social support is an important resource in the context of gender reassignment surgery. Understanding can help to improve the situation for transsexuals and to reduce consecutive healthcare utilisation.

Psychiatric comorbidity among patients with gender identity disorder.

PubMed

Hoshiai, Masahiko; Matsumoto, Yosuke; Sato, Toshiki; Ohnishi, Masaru; Okabe, Nobuyuki; Kishimoto, Yuki; Terada, Seishi; Kuroda, Shigetoshi

2010-10-01

Psychiatric comorbidity and mental instability seem to be important unfavorable prognostic factors for long-term psychosocial adjustment in gender identity disorder (GID). However, psychiatric comorbidity in patients with GID has rarely been assessed. In this study, we investigated the psychiatric comorbidity and life events of patients with GID in Japan. A total of 603 consecutive patients were evaluated independently by at least two senior psychiatrists at the GID clinic using clinical information and results of examinations. Using DSM-IV criteria, 579 patients (96.0%) were diagnosed with GID. Among the GID patients, 349 (60.3%) were the female-to-male (FTM) type, and 230 (39.7%) were the male-to-female (MTF) type. Current psychiatric comorbidity was 19.1% (44/230) among MTF patients and 12.0% (42/349) among FTM patients. The lifetime positive history of suicidal ideation and self mutilation was 76.1% and 31.7% among MTF patients, and 71.9% and 32.7% among FTM patients. Among current psychiatric diagnoses, adjustment disorder (6.7%, 38/579) and anxiety disorder (3.6%, 21/579) were relatively frequent. Mood disorder was the third most frequent (1.4%, 8/579). Comparison with previous reports on the psychiatric comorbidity among GID patients revealed that the majority of GID patients had no psychiatric comorbidity. GID is a diagnostic entity in its own right, not necessarily associated with severe comorbid psychological findings. © 2010 The Authors. Journal compilation © 2010 Japanese Society of Psychiatry and Neurology.

Research on camera on orbit radial calibration based on black body and infrared calibration stars

NASA Astrophysics Data System (ADS)

Wang, YuDu; Su, XiaoFeng; Zhang, WanYing; Chen, FanSheng

2018-05-01

Affected by launching process and space environment, the response capability of a space camera must be attenuated. So it is necessary for a space camera to have a spaceborne radiant calibration. In this paper, we propose a method of calibration based on accurate Infrared standard stars was proposed for increasing infrared radiation measurement precision. As stars can be considered as a point target, we use them as the radiometric calibration source and establish the Taylor expansion method and the energy extrapolation model based on WISE catalog and 2MASS catalog. Then we update the calibration results from black body. Finally, calibration mechanism is designed and the technology of design is verified by on orbit test. The experimental calibration result shows the irradiance extrapolation error is about 3% and the accuracy of calibration methods is about 10%, the results show that the methods could satisfy requirements of on orbit calibration.

A Comparison of Two Balance Calibration Model Building Methods

NASA Technical Reports Server (NTRS)

DeLoach, Richard; Ulbrich, Norbert

2007-01-01

Simulated strain-gage balance calibration data is used to compare the accuracy of two balance calibration model building methods for different noise environments and calibration experiment designs. The first building method obtains a math model for the analysis of balance calibration data after applying a candidate math model search algorithm to the calibration data set. The second building method uses stepwise regression analysis in order to construct a model for the analysis. Four balance calibration data sets were simulated in order to compare the accuracy of the two math model building methods. The simulated data sets were prepared using the traditional One Factor At a Time (OFAT) technique and the Modern Design of Experiments (MDOE) approach. Random and systematic errors were introduced in the simulated calibration data sets in order to study their influence on the math model building methods. Residuals of the fitted calibration responses and other statistical metrics were compared in order to evaluate the calibration models developed with different combinations of noise environment, experiment design, and model building method. Overall, predicted math models and residuals of both math model building methods show very good agreement. Significant differences in model quality were attributable to noise environment, experiment design, and their interaction. Generally, the addition of systematic error significantly degraded the quality of calibration models developed from OFAT data by either method, but MDOE experiment designs were more robust with respect to the introduction of a systematic component of the unexplained variance.

A forward bias method for lag correction of an a-Si flat panel detector

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

Starman, Jared; Tognina, Carlo; Partain, Larry

2012-01-15

Purpose: Digital a-Si flat panel (FP) x-ray detectors can exhibit detector lag, or residual signal, of several percent that can cause ghosting in projection images or severe shading artifacts, known as the radar artifact, in cone-beam computed tomography (CBCT) reconstructions. A major contributor to detector lag is believed to be defect states, or traps, in the a-Si layer of the FP. Software methods to characterize and correct for the detector lag exist, but they may make assumptions such as system linearity and time invariance, which may not be true. The purpose of this work is to investigate a new hardwaremore » based method to reduce lag in an a-Si FP and to evaluate its effectiveness at removing shading artifacts in CBCT reconstructions. The feasibility of a novel, partially hardware based solution is also examined. Methods: The proposed hardware solution for lag reduction requires only a minor change to the FP. For pulsed irradiation, the proposed method inserts a new operation step between the readout and data collection stages. During this new stage the photodiode is operated in a forward bias mode, which fills the defect states with charge. A Varian 4030CB panel was modified to allow for operation in the forward bias mode. The contrast of residual lag ghosts was measured for lag frames 2 and 100 after irradiation ceased for standard and forward bias modes. Detector step response, lag, SNR, modulation transfer function (MTF), and detective quantum efficiency (DQE) measurements were made with standard and forward bias firmware. CBCT data of pelvic and head phantoms were also collected. Results: Overall, the 2nd and 100th detector lag frame residual signals were reduced 70%-88% using the new method. SNR, MTF, and DQE measurements show a small decrease in collected signal and a small increase in noise. The forward bias hardware successfully reduced the radar artifact in the CBCT reconstruction of the pelvic and head phantoms by 48%-81%. Conclusions: Overall, the forward bias method has been found to greatly reduce detector lag ghosts in projection data and the radar artifact in CBCT reconstructions. The method is limited to improvements of the a-Si photodiode response only. A future hybrid mode may overcome any limitations of this method.« less

Geometric calibration of Colour and Stereo Surface Imaging System of ESA's Trace Gas Orbiter

NASA Astrophysics Data System (ADS)

Tulyakov, Stepan; Ivanov, Anton; Thomas, Nicolas; Roloff, Victoria; Pommerol, Antoine; Cremonese, Gabriele; Weigel, Thomas; Fleuret, Francois

2018-01-01

There are many geometric calibration methods for "standard" cameras. These methods, however, cannot be used for the calibration of telescopes with large focal lengths and complex off-axis optics. Moreover, specialized calibration methods for the telescopes are scarce in literature. We describe the calibration method that we developed for the Colour and Stereo Surface Imaging System (CaSSIS) telescope, on board of the ExoMars Trace Gas Orbiter (TGO). Although our method is described in the context of CaSSIS, with camera-specific experiments, it is general and can be applied to other telescopes. We further encourage re-use of the proposed method by making our calibration code and data available on-line.

Calibration of mass spectrometric peptide mass fingerprint data without specific external or internal calibrants

PubMed Central

Wolski, Witold E; Lalowski, Maciej; Jungblut, Peter; Reinert, Knut

2005-01-01

Background Peptide Mass Fingerprinting (PMF) is a widely used mass spectrometry (MS) method of analysis of proteins and peptides. It relies on the comparison between experimentally determined and theoretical mass spectra. The PMF process requires calibration, usually performed with external or internal calibrants of known molecular masses. Results We have introduced two novel MS calibration methods. The first method utilises the local similarity of peptide maps generated after separation of complex protein samples by two-dimensional gel electrophoresis. It computes a multiple peak-list alignment of the data set using a modified Minimum Spanning Tree (MST) algorithm. The second method exploits the idea that hundreds of MS samples are measured in parallel on one sample support. It improves the calibration coefficients by applying a two-dimensional Thin Plate Splines (TPS) smoothing algorithm. We studied the novel calibration methods utilising data generated by three different MALDI-TOF-MS instruments. We demonstrate that a PMF data set can be calibrated without resorting to external or relying on widely occurring internal calibrants. The methods developed here were implemented in R and are part of the BioConductor package mscalib available from . Conclusion The MST calibration algorithm is well suited to calibrate MS spectra of protein samples resulting from two-dimensional gel electrophoretic separation. The TPS based calibration algorithm might be used to correct systematic mass measurement errors observed for large MS sample supports. As compared to other methods, our combined MS spectra calibration strategy increases the peptide/protein identification rate by an additional 5 – 15%. PMID:16102175

An investigation into force-moment calibration techniques applicable to a magnetic suspension and balance system. M.S. Thesis

NASA Technical Reports Server (NTRS)

Eskins, Jonathan

1988-01-01

The problem of determining the forces and moments acting on a wind tunnel model suspended in a Magnetic Suspension and Balance System is addressed. Two calibration methods were investigated for three types of model cores, i.e., Alnico, Samarium-Cobalt, and a superconducting solenoid. Both methods involve calibrating the currents in the electromagnetic array against known forces and moments. The first is a static calibration method using calibration weights and a system of pulleys. The other method, dynamic calibration, involves oscillating the model and using its inertia to provide calibration forces and moments. Static calibration data, found to produce the most reliable results, is presented for three degrees of freedom at 0, 15, and -10 deg angle of attack. Theoretical calculations are hampered by the inability to represent iron-cored electromagnets. Dynamic calibrations, despite being quicker and easier to perform, are not as accurate as static calibrations. Data for dynamic calibrations at 0 and 15 deg is compared with the relevant static data acquired. Distortion of oscillation traces is cited as a major source of error in dynamic calibrations.

Performance evaluation and geologic utility of LANDSAT-4 thematic mapper data

NASA Technical Reports Server (NTRS)

Paylor, E. D.; Abrams, M. J.; Conel, J. E.; Kahle, A. B.; Lang, H. R.

1985-01-01

The overall objective of the project was to evaluate LANDSAT-4 Thematic Mapper (TM) data in the context of geologic applications. This involved a quantitative assessment of the data quality including the spatial and spectral characteristics realized by the instrument. Three test sites were selected for the study: (1) Silver Bell, Arizona; (2) Death Valley, California; and (3) Wind River/Bighorn Basin area, Wyoming. Conclusions include: (1) Artificial and natural targets can be used to atmospherically calibrate TM data and investigate scanner radiometry, atmospheric parameters, and construction of atmospheric Modulation Transfer Functions (MTF's), (2) No significant radiometric degradation occurs in TM data as a result of SCROUNGE processing; however, the data exhibit narrow digital number (DN) distributiosn suggesting that the configuration of the instrument is not optimal for each science applications, (30 Increased spatial resolution, 1:24,000 enlargement capability, and good geometric fidelity of TM data allow accurate photogeologic/geomorphic mapping, including relative age dating of alluvial fans, measurement of structural and bedding attitudes, and construction of such things as structural cross sections and stratigraphic columns. (4) TM bands 5 and 7 are particularly useful for geologic applications because they span a region of the spectrum not previously sampled by multispectral scanner data and are important for characterizing clay and carbonate materials.

The calibration methods for Multi-Filter Rotating Shadowband Radiometer: a review

NASA Astrophysics Data System (ADS)

Chen, Maosi; Davis, John; Tang, Hongzhao; Ownby, Carolyn; Gao, Wei

2013-09-01

The continuous, over two-decade data record from the Multi-Filter Rotating Shadowband Radiometer (MFRSR) is ideal for climate research which requires timely and accurate information of important atmospheric components such as gases, aerosols, and clouds. Except for parameters derived from MFRSR measurement ratios, which are not impacted by calibration error, most applications require accurate calibration factor(s), angular correction, and spectral response function(s) from calibration. Although a laboratory lamp (or reference) calibration can provide all the information needed to convert the instrument readings to actual radiation, in situ calibration methods are implemented routinely (daily) to fill the gaps between lamp calibrations. In this paper, the basic structure and the data collection and pretreatment of the MFRSR are described. The laboratory lamp calibration and its limitations are summarized. The cloud screening algorithms for MFRSR data are presented. The in situ calibration methods, the standard Langley method and its variants, the ratio-Langley method, the general method, Alexandrov's comprehensive method, and Chen's multi-channel method, are outlined. The reason that all these methods do not fit for all situations is that they assume some properties, such as aerosol optical depth (AOD), total optical depth (TOD), precipitable water vapor (PWV), effective size of aerosol particles, or angstrom coefficient, are invariant over time. These properties are not universal and some of them rarely happen. In practice, daily calibration factors derived from these methods should be smoothed to restrain error.

Simple transfer calibration method for a Cimel Sun-Moon photometer: calculating lunar calibration coefficients from Sun calibration constants.

PubMed

Li, Zhengqiang; Li, Kaitao; Li, Donghui; Yang, Jiuchun; Xu, Hua; Goloub, Philippe; Victori, Stephane

2016-09-20

The Cimel new technologies allow both daytime and nighttime aerosol optical depth (AOD) measurements. Although the daytime AOD calibration protocols are well established, accurate and simple nighttime calibration is still a challenging task. Standard lunar-Langley and intercomparison calibration methods both require specific conditions in terms of atmospheric stability and site condition. Additionally, the lunar irradiance model also has some known limits on its uncertainty. This paper presents a simple calibration method that transfers the direct-Sun calibration constant, V_0,Sun, to the lunar irradiance calibration coefficient, C_Moon. Our approach is a pure calculation method, independent of site limits, e.g., Moon phase. The method is also not affected by the lunar irradiance model limitations, which is the largest error source of traditional calibration methods. Besides, this new transfer calibration approach is easy to use in the field since C_Moon can be obtained directly once V_0,Sun is known. Error analysis suggests that the average uncertainty of C_Moon over the 440-1640 nm bands obtained with the transfer method is 2.4%-2.8%, depending on the V_0,Sun approach (Langley or intercomparison), which is comparable with that of lunar-Langley approach, theoretically. In this paper, the Sun-Moon transfer and the Langley methods are compared based on site measurements in Beijing, and the day-night measurement continuity and performance are analyzed.

Sensor performance analysis

NASA Technical Reports Server (NTRS)

Montgomery, H. E.; Ostrow, H.; Ressler, G. M.

1990-01-01

The theory is described and the equations required to design are developed and the performance of electro-optical sensor systems that operate from the visible through the thermal infrared spectral regions are analyzed. Methods to compute essential optical and detector parameters, signal-to-noise ratio, MTF, and figures of merit such as NE delta rho and NE delta T are developed. A set of atmospheric tables are provided to determine scene radiance in the visible spectral region. The Planck function is used to determine radiance in the infrared. The equations developed were incorporated in a spreadsheet so that a wide variety of sensor studies can be rapidly and efficiently conducted.

Optimized star sensors laboratory calibration method using a regularization neural network.

PubMed

Zhang, Chengfen; Niu, Yanxiong; Zhang, Hao; Lu, Jiazhen

2018-02-10

High-precision ground calibration is essential to ensure the performance of star sensors. However, the complex distortion and multi-error coupling have brought great difficulties to traditional calibration methods, especially for large field of view (FOV) star sensors. Although increasing the complexity of models is an effective way to improve the calibration accuracy, it significantly increases the demand for calibration data. In order to achieve high-precision calibration of star sensors with large FOV, a novel laboratory calibration method based on a regularization neural network is proposed. A multi-layer structure neural network is designed to represent the mapping of the star vector and the corresponding star point coordinate directly. To ensure the generalization performance of the network, regularization strategies are incorporated into the net structure and the training algorithm. Simulation and experiment results demonstrate that the proposed method can achieve high precision with less calibration data and without any other priori information. Compared with traditional methods, the calibration error of the star sensor decreased by about 30%. The proposed method can satisfy the precision requirement for large FOV star sensors.

Features calibration of the dynamic force transducers

NASA Astrophysics Data System (ADS)

Sc., M. Yu Prilepko D.; Lysenko, V. G.

2018-04-01

The article discusses calibration methods of dynamic forces measuring instruments. The relevance of work is dictated by need to valid definition of the dynamic forces transducers metrological characteristics taking into account their intended application. The aim of this work is choice justification of calibration method, which provides the definition dynamic forces transducers metrological characteristics under simulation operating conditions for determining suitability for using in accordance with its purpose. The following tasks are solved: the mathematical model and the main measurements equation of calibration dynamic forces transducers by load weight, the main budget uncertainty components of calibration are defined. The new method of dynamic forces transducers calibration with use the reference converter “force-deformation” based on the calibrated elastic element and measurement of his deformation by a laser interferometer is offered. The mathematical model and the main measurements equation of the offered method is constructed. It is shown that use of calibration method based on measurements by the laser interferometer of calibrated elastic element deformations allows to exclude or to considerably reduce the uncertainty budget components inherent to method of load weight.

Radiometer calibration methods and resulting irradiance differences: Radiometer calibration methods and resulting irradiance differences

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

Habte, Aron; Sengupta, Manajit; Andreas, Afshin

Accurate solar radiation measured by radiometers depends on instrument performance specifications, installation method, calibration procedure, measurement conditions, maintenance practices, location, and environmental conditions. This study addresses the effect of different calibration methodologies and resulting differences provided by radiometric calibration service providers such as the National Renewable Energy Laboratory (NREL) and manufacturers of radiometers. Some of these methods calibrate radiometers indoors and some outdoors. To establish or understand the differences in calibration methodologies, we processed and analyzed field-measured data from radiometers deployed for 10 months at NREL's Solar Radiation Research Laboratory. These different methods of calibration resulted in a difference ofmore » +/-1% to +/-2% in solar irradiance measurements. Analyzing these differences will ultimately assist in determining the uncertainties of the field radiometer data and will help develop a consensus on a standard for calibration. Further advancing procedures for precisely calibrating radiometers to world reference standards that reduce measurement uncertainties will help the accurate prediction of the output of planned solar conversion projects and improve the bankability of financing solar projects.« less

Research on the calibration methods of the luminance parameter of radiation luminance meters

NASA Astrophysics Data System (ADS)

Cheng, Weihai; Huang, Biyong; Lin, Fangsheng; Li, Tiecheng; Yin, Dejin; Lai, Lei

2017-10-01

This paper introduces standard diffusion reflection white plate method and integrating sphere standard luminance source method to calibrate the luminance parameter. The paper compares the effects of calibration results by using these two methods through principle analysis and experimental verification. After using two methods to calibrate the same radiation luminance meter, the data obtained verifies the testing results of the two methods are both reliable. The results show that the display value using standard white plate method has fewer errors and better reproducibility. However, standard luminance source method is more convenient and suitable for on-site calibration. Moreover, standard luminance source method has wider range and can test the linear performance of the instruments.

Evaluating the Biostability of Yellow and Clear Intraocular Lenses with a System Simulating Natural Intraocular Environment

PubMed Central

Hayashi, Rijo; Hayashi, Shimmin; Arai, Kiyomi; Yoshida, Shinichirou; Chikuda, Makoto; Machida, Shigeki

2016-01-01

Purpose Blue light–filtering intraocular lenses (IOLs) are thought to protect the retina from blue light damage after cataract surgery, and the implantation of yellow-tinted IOLs has been commonly used in cataract surgery. To our knowledge, this is the first investigation measuring the long-term biostability of yellow-tinted IOLs using an in vitro system simulating natural intraocular environment. Methods Six hydrophobic acrylic IOLs, three clear IOLs, and three yellow-tinted IOLs were included in the study. Each yellow-tinted IOL was a matching counterpart of a clear IOL, with the only difference being the lens color. The IOLs were kept in conditions replicating the intraocular environment using a perfusion culture system for 7 months. Resolution, light transmittance rate, and the modulation transfer function (MTF) were measured before and after culturing. Surface roughness of the anterior and posterior surfaces was also measured. Results After culturing for 7 months, there were no changes in the resolution, the light transmittance rate, and MTF. The surface roughness of the anterior and posterior surfaces increased after culturing; however, this increase was clinically insignificant. There were no differences in surface roughness between the clear and yellow-tinted IOLs, either before or after culturing. Conclusions A novel in vitro system replicating intraocular environment was used to investigate the biostability of yellow-tinted IOLs. The surface roughness showed no clinically significant increase after culturing for 7 months. Translational Relevance This system is useful for evaluating the biostability of IOLs. PMID:27933221

High-resolution x-ray imaging using a structured scintillator

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

Hormozan, Yashar, E-mail: hormozan@kth.se; Sychugov, Ilya; Linnros, Jan

2016-02-15

Purpose: In this study, the authors introduce a new generation of finely structured scintillators with a very high spatial resolution (a few micrometers) compared to conventional scintillators, yet maintaining a thick absorbing layer for improved detectivity. Methods: Their concept is based on a 2D array of high aspect ratio pores which are fabricated by ICP etching, with spacings (pitches) of a few micrometers, on silicon and oxidation of the pore walls. The pores were subsequently filled by melting of powdered CsI(Tl), as the scintillating agent. In order to couple the secondary emitted photons of the back of the scintillator arraymore » to a CCD device, having a larger pixel size than the pore pitch, an open optical microscope with adjustable magnification was designed and implemented. By imaging a sharp edge, the authors were able to calculate the modulation transfer function (MTF) of this finely structured scintillator. Results: The x-ray images of individually resolved pores suggest that they have been almost uniformly filled, and the MTF measurements show the feasibility of a few microns spatial resolution imaging, as set by the scintillator pore size. Compared to existing techniques utilizing CsI needles as a structured scintillator, their results imply an almost sevenfold improvement in resolution. Finally, high resolution images, taken by their detector, are presented. Conclusions: The presented work successfully shows the functionality of their detector concept for high resolution imaging and further fabrication developments are most likely to result in higher quantum efficiencies.« less

[Analysis of stress in periodontal ligament of the maxillary first molar on distal movement by nonlinear finite element method].

PubMed

Dong, Jing; Zhang, Zhe-chen; Zhou, Guo-liang

2015-06-01

To analyze the stress distribution in periodontal ligament of maxillary first molar during distal movement with nonlinear finite element analysis, and to compare it with the result of linear finite element analysis, consequently to provide biomechanical evidence for clinical application. The 3-D finite element model including a maxillary first molar, periodontal ligament, alveolar bone, cancellous bone, cortical bone and a buccal tube was built up by using Mimics, Geomagic, ProE and Ansys Workbench. The material of periodontal ligament was set as nonlinear material and linear elastic material, respectively. Loads of different combinations were applied to simulate the clinical situation of distalizing the maxillary first molar. There were channels of low stress in peak distribution of Von Mises equivalent stress and compressive stress of periodontal ligament in nonlinear finite element model. The peak of Von Mises equivalent stress was lower when it was satisfied that Mt/F minus Mr/F approximately equals 2. The peak of compressive stress was lower when it was satisfied that Mt/F was approximately equal to Mr/F. The relative stress of periodontal ligament was higher and violent in linear finite element model and there were no channels of low stress in peak distribution. There are channels in which stress of periodontal ligament is lower. The condition of low stress should be satisfied by applied M/F during the course of distalizing the maxillary first molar.

The School Food Environment and Student BMI and Food Consumption: 2004 to 2007 National Data

PubMed Central

Terry-McElrath, Yvonne M.; O’Malley, Patrick M.; Delva, Jorge; Johnston, Lloyd D.

2009-01-01

Purpose This study identifies trends in the availability of various food choices in United States’ middle and high schools from 2004–2007, and examines the potential associations between such food availability and students’ self-reported eating habits and BMI-related outcomes. Methods Data are based on nationally representative samples of 78,442 students in 684 secondary schools surveyed from 2004 to 2007 as part of the Youth, Education, and Society (YES) study and the Monitoring the Future (MTF) study. In the YES study, school administrators and food service managers completed self-administered questionnaires on their school’s food environment. In the MTF study, students in the same schools completed self-administered questionnaires, providing data used to construct BMI and food consumption measures. Results Overall, there was a decrease in the availability of regular sugar/fat food items in both middle and high schools, and some indication of an increase high school availability of reduced fat food items through school lunch or a la carte. Some minimal evidence was found for relationships between the school food environment and student BMI-related outcomes and food consumption measures. Conclusions United States secondary schools are making progress in the types of foods offered to students, with food items of lower nutritional value becoming less prevalent in recent years. Continued monitoring of food environment trends may help clarify if and how such factors relate to youth health outcomes. PMID:19699436

A novel dual-camera calibration method for 3D optical measurement

NASA Astrophysics Data System (ADS)

Gai, Shaoyan; Da, Feipeng; Dai, Xianqiang

2018-05-01

A novel dual-camera calibration method is presented. In the classic methods, the camera parameters are usually calculated and optimized by the reprojection error. However, for a system designed for 3D optical measurement, this error does not denote the result of 3D reconstruction. In the presented method, a planar calibration plate is used. In the beginning, images of calibration plate are snapped from several orientations in the measurement range. The initial parameters of the two cameras are obtained by the images. Then, the rotation and translation matrix that link the frames of two cameras are calculated by using method of Centroid Distance Increment Matrix. The degree of coupling between the parameters is reduced. Then, 3D coordinates of the calibration points are reconstructed by space intersection method. At last, the reconstruction error is calculated. It is minimized to optimize the calibration parameters. This error directly indicates the efficiency of 3D reconstruction, thus it is more suitable for assessing the quality of dual-camera calibration. In the experiments, it can be seen that the proposed method is convenient and accurate. There is no strict requirement on the calibration plate position in the calibration process. The accuracy is improved significantly by the proposed method.

Finding trap stiffness of optical tweezers using digital filters.

PubMed

Almendarez-Rangel, Pedro; Morales-Cruzado, Beatriz; Sarmiento-Gómez, Erick; Pérez-Gutiérrez, Francisco G

2018-02-01

Obtaining trap stiffness and calibration of the position detection system is the basis of a force measurement using optical tweezers. Both calibration quantities can be calculated using several experimental methods available in the literature. In most cases, stiffness determination and detection system calibration are performed separately, often requiring procedures in very different conditions, and thus confidence of calibration methods is not assured due to possible changes in the environment. In this work, a new method to simultaneously obtain both the detection system calibration and trap stiffness is presented. The method is based on the calculation of the power spectral density of positions through digital filters to obtain the harmonic contributions of the position signal. This method has the advantage of calculating both trap stiffness and photodetector calibration factor from the same dataset in situ. It also provides a direct method to avoid unwanted frequencies that could greatly affect calibration procedure, such as electric noise, for example.

Improvement of Gaofen-3 Absolute Positioning Accuracy Based on Cross-Calibration

PubMed Central

Deng, Mingjun; Li, Jiansong

2017-01-01

The Chinese Gaofen-3 (GF-3) mission was launched in August 2016, equipped with a full polarimetric synthetic aperture radar (SAR) sensor in the C-band, with a resolution of up to 1 m. The absolute positioning accuracy of GF-3 is of great importance, and in-orbit geometric calibration is a key technology for improving absolute positioning accuracy. Conventional geometric calibration is used to accurately calibrate the geometric calibration parameters of the image (internal delay and azimuth shifts) using high-precision ground control data, which are highly dependent on the control data of the calibration field, but it remains costly and labor-intensive to monitor changes in GF-3’s geometric calibration parameters. Based on the positioning consistency constraint of the conjugate points, this study presents a geometric cross-calibration method for the rapid and accurate calibration of GF-3. The proposed method can accurately calibrate geometric calibration parameters without using corner reflectors and high-precision digital elevation models, thus improving absolute positioning accuracy of the GF-3 image. GF-3 images from multiple regions were collected to verify the absolute positioning accuracy after cross-calibration. The results show that this method can achieve a calibration accuracy as high as that achieved by the conventional field calibration method. PMID:29240675

Radiometric calibration of the Earth observing system's imaging sensors

NASA Technical Reports Server (NTRS)

Slater, P. N.

1987-01-01

Philosophy, requirements, and methods of calibration of multispectral space sensor systems as applicable to the Earth Observing System (EOS) are discussed. Vicarious methods for calibration of low spatial resolution systems, with respect to the Advanced Very High Resolution Radiometer (AVHRR), are then summarized. Finally, a theoretical introduction is given to a new vicarious method of calibration using the ratio of diffuse-to-global irradiance at the Earth's surfaces as the key input. This may provide an additional independent method for in-flight calibration.

Configurations and calibration methods for passive sampling techniques.

PubMed

Ouyang, Gangfeng; Pawliszyn, Janusz

2007-10-19

Passive sampling technology has developed very quickly in the past 15 years, and is widely used for the monitoring of pollutants in different environments. The design and quantification of passive sampling devices require an appropriate calibration method. Current calibration methods that exist for passive sampling, including equilibrium extraction, linear uptake, and kinetic calibration, are presented in this review. A number of state-of-the-art passive sampling devices that can be used for aqueous and air monitoring are introduced according to their calibration methods.

Application of composite small calibration objects in traffic accident scene photogrammetry.

PubMed

Chen, Qiang; Xu, Hongguo; Tan, Lidong

2015-01-01

In order to address the difficulty of arranging large calibration objects and the low measurement accuracy of small calibration objects in traffic accident scene photogrammetry, a photogrammetric method based on a composite of small calibration objects is proposed. Several small calibration objects are placed around the traffic accident scene, and the coordinate system of the composite calibration object is given based on one of them. By maintaining the relative position and coplanar relationship of the small calibration objects, the local coordinate system of each small calibration object is transformed into the coordinate system of the composite calibration object. The two-dimensional direct linear transformation method is improved based on minimizing the reprojection error of the calibration points of all objects. A rectified image is obtained using the nonlinear optimization method. The increased accuracy of traffic accident scene photogrammetry using a composite small calibration object is demonstrated through the analysis of field experiments and case studies.

Signal inference with unknown response: calibration-uncertainty renormalized estimator.

PubMed

Dorn, Sebastian; Enßlin, Torsten A; Greiner, Maksim; Selig, Marco; Boehm, Vanessa

2015-01-01

The calibration of a measurement device is crucial for every scientific experiment, where a signal has to be inferred from data. We present CURE, the calibration-uncertainty renormalized estimator, to reconstruct a signal and simultaneously the instrument's calibration from the same data without knowing the exact calibration, but its covariance structure. The idea of the CURE method, developed in the framework of information field theory, is to start with an assumed calibration to successively include more and more portions of calibration uncertainty into the signal inference equations and to absorb the resulting corrections into renormalized signal (and calibration) solutions. Thereby, the signal inference and calibration problem turns into a problem of solving a single system of ordinary differential equations and can be identified with common resummation techniques used in field theories. We verify the CURE method by applying it to a simplistic toy example and compare it against existent self-calibration schemes, Wiener filter solutions, and Markov chain Monte Carlo sampling. We conclude that the method is able to keep up in accuracy with the best self-calibration methods and serves as a noniterative alternative to them.

Characteristic investigation of Golay9 multiple mirror telescope with a spherical primary mirror

NASA Astrophysics Data System (ADS)

Wu, Feng; Wu, Quanying; Zhu, Xifang; Xiang, Ruxi; Qian, Lin

2017-10-01

The sparse aperture provides a novel solution to the manufacturing difficulties of modern super large telescopes. Golay configurations are optimal in the sparse aperture family. Characteristics of the Golay9 multiple mirror telescope having a spherical primary mirror are investigated. The arrangement of the nine sub-mirrors is discussed after the planar Golay9 configuration is analyzed. The characteristics of the entrance pupil are derived by analyzing the sub-aperture shapes with different relative apertures and sub-mirror sizes. Formulas about the fill factor and the overlay factor are deduced. Their maximal values are presented based on the derived tangency condition. Formulas for the point spread function (PSF) and the modulation transfer function (MTF) of the Golay9 MMT are also deduced. Two Golay9 MMT have been developed by Zemax simulation. Their PSF, MTF, fill factors, and overlay factors prove that our theoretical results are consistent with the practical simulation ones.

Correlation between Post-LASIK Starburst Symptom and Ocular Wavefront Aberrations

NASA Astrophysics Data System (ADS)

Liu, Yong-Ji; Mu, Guo-Guang; Wang, Zhao-Qi; Wang-Yan

2006-06-01

Monochromatic aberrations in post laser in-situ keratomileusis (LASIK) eyes are measured. The data are categorized into reference group and starburst group according to the visual symptoms. Statistic analysis has been made to find the correlation between the ocular wavefront aberrations and the starburst symptom. The rms aberrations of the 3rd and 4th orders for the starburst group are significantly larger than those for the reference group. The starburst symptom shows a strong correlation with vertical coma, total coma, spherical aberrations. For 3-mm pupil size and 5.8-mm pupil size, the modulation transfer function (MTF) of the starburst group are lower than those of the reference group, but their visual acuities are close. MTF and PSF analyses are made for two groups, and the results are consistent with the statistical analysis, which means the difference between the two groups is mainly due to the third- and fourth-order Zernike aberrations.

Study of Permanent Magnet Focusing for Astronomical Camera Tubes

NASA Technical Reports Server (NTRS)

Long, D. C.; Lowrance, J. L.

1975-01-01

A design is developed of a permanent magnet assembly (PMA) useful as the magnetic focusing unit for the 35 and 70 mm (diagonal) format SEC tubes. Detailed PMA designs for both tubes are given, and all data on their magnetic configuration, size, weight, and structure of magnetic shields adequate to screen the camera tube from the earth's magnetic field are presented. A digital computer is used for the PMA design simulations, and the expected operational performance of the PMA is ascertained through the calculation of a series of photoelectron trajectories. A large volume where the magnetic field uniformity is greater than 0.5% appears obtainable, and the point spread function (PSF) and modulation transfer function(MTF) indicate nearly ideal performance. The MTF at 20 cycles per mm exceeds 90%. The weight and volume appear tractable for the large space telescope and ground based application.

Adiabatic model and design of a translating field reversed configuration

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

Intrator, T. P.; Siemon, R. E.; Sieck, P. E.

We apply an adiabatic evolution model to predict the behavior of a field reversed configuration (FRC) during decompression and translation, as well as during boundary compression. Semi-empirical scaling laws, which were developed and benchmarked primarily for collisionless FRCs, are expected to remain valid even for the collisional regime of FRX-L experiment. We use this approach to outline the design implications for FRX-L, the high density translated FRC experiment at Los Alamos National Laboratory. A conical theta coil is used to accelerate the FRC to the largest practical velocity so it can enter a mirror bounded compression region, where it mustmore » be a suitable target for a magnetized target fusion (MTF) implosion. FRX-L provides the physics basis for the integrated MTF plasma compression experiment at the Shiva-Star pulsed power facility at Kirtland Air Force Research Laboratory, where the FRC will be compressed inside a flux conserving cylindrical shell.« less

Saturn Apollo Program

NASA Image and Video Library

1967-01-01

This photograph shows a test firing of the the Saturn V S-II (second) stage at the Mississippi Test Facility's (MTF) S-II test stand. When the Saturn V booster stage (S-IC) burns out and drops away, power for the Saturn will be provided by the 82-foot-long and 33-foot-diameter S-II stage. Developed by the Space Division of North American Aviation under the direction of the Marshall Space Flight Center, the stage utilized five J-2 engines, each producing 200,000 pounds of thrust. The engines used liquid oxygen and liquid hydrogen as propellants. Static test of ground test versions of the S-II stage were conducted at North American Aviation's Santa Susana, California test site. All flight stages were tested at the Mississippi Test Facility, Bay St. Louis, Mississippi. MTF was renamed to the National Space Technology Laboratory (NSTL) in 1974 and later to the Sternis Space Center in May 1988.

Saturn Apollo Program

NASA Image and Video Library

1967-01-01

This photograph shows a test firing of the the Saturn V S-II (second) stage at the Mississippi Test Facility's (MTF) S-II test stand. When the Saturn V booster stage (S-IC) burns out and drops away, power for the Saturn will be provided by the 82-foot-long and 33-foot-diameter S-II stage. Developed by the Space Division of North American Aviation under the direction of the Marshall Space Flight Center, the stage utilized five J-2 engines, each producing 200,000 pounds of thrust. The engine used liquid oxygen and liquid hydrogen as its propellants. Static test of ground test versions of the S-II stage were conducted at North American Aviation's Santa Susana, California test site. All flight stages were tested at the Mississippi Test Facility, Bay St. Louis, Mississippi. The MTF was renamed to the National Space Technology Laboratory (NSTL) in 1974 and later to the Sternis Space Center (SSC) in May 1988.

A real-time MTFC algorithm of space remote-sensing camera based on FPGA

NASA Astrophysics Data System (ADS)

Zhao, Liting; Huang, Gang; Lin, Zhe

2018-01-01

A real-time MTFC algorithm of space remote-sensing camera based on FPGA was designed. The algorithm can provide real-time image processing to enhance image clarity when the remote-sensing camera running on-orbit. The image restoration algorithm adopted modular design. The MTF measurement calculation module on-orbit had the function of calculating the edge extension function, line extension function, ESF difference operation, normalization MTF and MTFC parameters. The MTFC image filtering and noise suppression had the function of filtering algorithm and effectively suppressing the noise. The algorithm used System Generator to design the image processing algorithms to simplify the design structure of system and the process redesign. The image gray gradient dot sharpness edge contrast and median-high frequency were enhanced. The image SNR after recovery reduced less than 1 dB compared to the original image. The image restoration system can be widely used in various fields.

The Joint Military Medical Executive Skills initiative: an impressive response to changing human resource management rules of engagement.

PubMed

Kerr, Bernard J

2007-01-01

Confronted with a sudden and substantial change in the rules regarding who could command a military medical treatment facility (MTF), the Military Health System (MHS) responded to the challenge with an impressive human resource management solution-the Joint Medical Executive Skills Program. The history, emergence, and continuing role of this initiative exemplifies the MHS's capacity to fulfill the spirit and intent of an arduous Congressional mandate while enhancing professional development and sustaining the career opportunities of medical officers. The MHS response to the Congressional requirement that candidates for MTF command demonstrate professional administrative skills was decisive, creative, and consistent with the basic principles of human resource management. The Joint Medical Executive Skills Program is a management success story that demonstrates how strategic planning, well-defined skills requirements, and structured training can assure a ready supply of qualified commanders for the military's MTFs.

Structured light system calibration method with optimal fringe angle.

PubMed

Li, Beiwen; Zhang, Song

2014-11-20

For structured light system calibration, one popular approach is to treat the projector as an inverse camera. This is usually performed by projecting horizontal and vertical sequences of patterns to establish one-to-one mapping between camera points and projector points. However, for a well-designed system, either horizontal or vertical fringe images are not sensitive to depth variation and thus yield inaccurate mapping. As a result, the calibration accuracy is jeopardized if a conventional calibration method is used. To address this limitation, this paper proposes a novel calibration method based on optimal fringe angle determination. Experiments demonstrate that our calibration approach can increase the measurement accuracy up to 38% compared to the conventional calibration method with a calibration volume of 300(H)  mm×250(W)  mm×500(D)  mm.

Simultaneous calibration phantom commission and geometry calibration in cone beam CT

NASA Astrophysics Data System (ADS)

Xu, Yuan; Yang, Shuai; Ma, Jianhui; Li, Bin; Wu, Shuyu; Qi, Hongliang; Zhou, Linghong

2017-09-01

Geometry calibration is a vital step for describing the geometry of a cone beam computed tomography (CBCT) system and is a prerequisite for CBCT reconstruction. In current methods, calibration phantom commission and geometry calibration are divided into two independent tasks. Small errors in ball-bearing (BB) positioning in the phantom-making step will severely degrade the quality of phantom calibration. To solve this problem, we propose an integrated method to simultaneously realize geometry phantom commission and geometry calibration. Instead of assuming the accuracy of the geometry phantom, the integrated method considers BB centers in the phantom as an optimized parameter in the workflow. Specifically, an evaluation phantom and the corresponding evaluation contrast index are used to evaluate geometry artifacts for optimizing the BB coordinates in the geometry phantom. After utilizing particle swarm optimization, the CBCT geometry and BB coordinates in the geometry phantom are calibrated accurately and are then directly used for the next geometry calibration task in other CBCT systems. To evaluate the proposed method, both qualitative and quantitative studies were performed on simulated and realistic CBCT data. The spatial resolution of reconstructed images using dental CBCT can reach up to 15 line pair cm-1. The proposed method is also superior to the Wiesent method in experiments. This paper shows that the proposed method is attractive for simultaneous and accurate geometry phantom commission and geometry calibration.

Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film.

PubMed

Gotanda, Tatsuhiro; Katsuda, Toshizo; Gotanda, Rumi; Kuwano, Tadao; Akagawa, Takuya; Tanki, Nobuyoshi; Tabuchi, Akihiko; Shimono, Tetsunori; Kawaji, Yasuyuki

2016-01-01

Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were -32.336 and -33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range.

Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film

PubMed Central

Gotanda, Tatsuhiro; Katsuda, Toshizo; Gotanda, Rumi; Kuwano, Tadao; Akagawa, Takuya; Tanki, Nobuyoshi; Tabuchi, Akihiko; Shimono, Tetsunori; Kawaji, Yasuyuki

2016-01-01

Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were −32.336 and −33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range. PMID:28144120

A new systematic calibration method of ring laser gyroscope inertial navigation system

NASA Astrophysics Data System (ADS)

Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Xiong, Zhenyu; Long, Xingwu

2016-10-01

Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.

Calibrating the stress-time curve of a combined finite-discrete element method to a Split Hopkinson Pressure Bar experiment

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

Osthus, Dave; Godinez, Humberto C.; Rougier, Esteban

We presenmore » t a generic method for automatically calibrating a computer code to an experiment, with uncertainty, for a given “training” set of computer code runs. The calibration technique is general and probabilistic, meaning the calibration uncertainty is represented in the form of a probability distribution. We demonstrate the calibration method by calibrating a combined Finite-Discrete Element Method (FDEM) to a Split Hopkinson Pressure Bar (SHPB) experiment with a granite sample. The probabilistic calibration method combines runs of a FDEM computer simulation for a range of “training” settings and experimental uncertainty to develop a statistical emulator. The process allows for calibration of input parameters and produces output quantities with uncertainty estimates for settings where simulation results are desired. Input calibration and FDEM fitted results are presented. We find that the maximum shear strength σ t max and to a lesser extent maximum tensile strength σ n max govern the behavior of the stress-time curve before and around the peak, while the specific energy in Mode II (shear) E t largely governs the post-peak behavior of the stress-time curve. Good agreement is found between the calibrated FDEM and the SHPB experiment. Interestingly, we find the SHPB experiment to be rather uninformative for calibrating the softening-curve shape parameters (a, b, and c). This work stands as a successful demonstration of how a general probabilistic calibration framework can automatically calibrate FDEM parameters to an experiment.« less

Calibrating the stress-time curve of a combined finite-discrete element method to a Split Hopkinson Pressure Bar experiment

DOE PAGES

Osthus, Dave; Godinez, Humberto C.; Rougier, Esteban; ...

2018-05-01

We presenmore » t a generic method for automatically calibrating a computer code to an experiment, with uncertainty, for a given “training” set of computer code runs. The calibration technique is general and probabilistic, meaning the calibration uncertainty is represented in the form of a probability distribution. We demonstrate the calibration method by calibrating a combined Finite-Discrete Element Method (FDEM) to a Split Hopkinson Pressure Bar (SHPB) experiment with a granite sample. The probabilistic calibration method combines runs of a FDEM computer simulation for a range of “training” settings and experimental uncertainty to develop a statistical emulator. The process allows for calibration of input parameters and produces output quantities with uncertainty estimates for settings where simulation results are desired. Input calibration and FDEM fitted results are presented. We find that the maximum shear strength σ t max and to a lesser extent maximum tensile strength σ n max govern the behavior of the stress-time curve before and around the peak, while the specific energy in Mode II (shear) E t largely governs the post-peak behavior of the stress-time curve. Good agreement is found between the calibrated FDEM and the SHPB experiment. Interestingly, we find the SHPB experiment to be rather uninformative for calibrating the softening-curve shape parameters (a, b, and c). This work stands as a successful demonstration of how a general probabilistic calibration framework can automatically calibrate FDEM parameters to an experiment.« less

Subjective Visual Performance and Objective Optical Quality With Intraocular Lens Glistening and Surface Light Scattering.

PubMed

Luo, Furong; Bao, Xuan; Qin, Yingyan; Hou, Min; Wu, Mingxing

2018-06-01

To evaluate the long-term effect of glistenings and surface light scattering of intraocular lenses (IOLs) on visual and optical performance after cataract surgery. Pseudophakic eyes that underwent standard phacoemulsification and two types of hydrophobic acrylic spherical IOL implantation without complications for at least 5 years were included in this retrospective study. Participants were divided into the glistenings, surface light scattering, and control groups according to the current condition of the IOLs. Then participants received a follow-up examination including uncorrected and corrected distance visual acuity (UDVA and CDVA), contrast sensitivity, straylight, and intraocular higher order aberrations, as well as point spread function (PSF) and modulation transfer function (MTF). A total of 140 eyes were included in the study. UDVA, CDVA, and glare sensitivity were not significantly different among the three groups (P > .05). However, compared with the control group, the IOLs of the glistenings and surface light scattering groups were associated with significantly lower contrast sensitivity under no glare conditions. Furthermore, eye with glistenings exhibited the highest straylight value (P < .05), whereas no difference was found between the surface light scattering and control groups. In contrast to the control group, the spherical aberration increased and the mean values of PSF and MTF decreased in the glistenings and surface light scattering groups. Both glistenings and surface light scattering tend to impair subjective visual performance, such as contrast sensitivity, and potentially affect objective optical quality, including straylight, spherical aberration, PSF, and MTF. [J Refract Surg. 2018;34(6):372-378.]. Copyright 2018, SLACK Incorporated.

[High-contrast resolution of film-screen systems in oral and maxillofacial radiology].

PubMed

Kaeppler, G; Reinert, S

2007-11-01

The aim was to determine differences in high-contrast resolution of film-screen systems used in dental panoramic and cephalometric radiography by calculating the modulation transfer function (MTF). The radiographs used to determine the MTF should be taken by the same x-ray units as those used for patient radiographs. The MTF was determined using a lead grid and according to DIN 6867-2 for 11 film-screen systems (speed 250, speed class 200 and 400) used in dental radiographic diagnostics. The optical density was measured using a microdensitometer developed by PTB. With 10% of the modulation transfer factor, newly developed film-screen systems (speed class 200 and 400) demonstrated a resolution of 4.9 to 6 line pairs per mm (panoramic radiography). In cephalometric radiography a film-screen system (speed class 400 and green-sensitive film) had a resolution of 4.2 line pairs per mm and surpassed two film-screen systems (speed class 400, resolution of 3 line pairs per mm, blue-sensitive films). The relevance of this study is underlined by the diagnostic reference doses defined in the German X-ray Ordinance (RöV) which are also intended for dentistry. Film-screen systems (speed 250, speed class 200) previously used in dental panoramic and cephalometric radiography can be replaced by newly developed film-screen systems (speed class 400). In dental radiography dose reductions are possible with film-screen systems (speed class 400) without impairing diagnostic accuracy. The introduction of newly developed film-screen systems (speed class 400) requires lower milliampere-seconds and therefore an adjustment of the x-ray units to lower milliampere settings.

Free software for performing physical analysis of systems for digital radiography and mammography.

PubMed

Donini, Bruno; Rivetti, Stefano; Lanconelli, Nico; Bertolini, Marco

2014-05-01

In this paper, the authors present a free software for assisting users in achieving the physical characterization of x-ray digital systems and image quality checks. The program was developed as a plugin of a well-known public-domain suite ImageJ. The software can assist users in calculating various physical parameters such as the response curve (also termed signal transfer property), modulation transfer function (MTF), noise power spectra (NPS), and detective quantum efficiency (DQE). It also includes the computation of some image quality checks: defective pixel analysis, uniformity, dark analysis, and lag. The software was made available in 2009 and has been used during the last couple of years by many users who gave us valuable feedback for improving its usability. It was tested for achieving the physical characterization of several clinical systems for digital radiography and mammography. Various published papers made use of the outcomes of the plugin. This software is potentially beneficial to a variety of users: physicists working in hospitals, staff working in radiological departments, such as medical physicists, physicians, engineers. The plugin, together with a brief user manual, are freely available and can be found online (www.medphys.it/downloads.htm). With our plugin users can estimate all three most important parameters used for physical characterization (MTF, NPS, and also DQE). The plugin can run on any operating system equipped with ImageJ suite. The authors validated the software by comparing MTF and NPS curves on a common set of images with those obtained with other dedicated programs, achieving a very good agreement.

In vitro optical quality of monofocal aspheric toric intraocular lenses: effect of cylindrical power.

PubMed

Ferrer-Blasco, Teresa; Domínguez-Vicent, Alberto; García-Lázaro, Santiago; Diez, María Amparo; Alfonso, José F; Esteve-Taboada, José J

2018-06-01

To assess the in vitro optical quality of monofocal aspheric toric intraocular lenses (IOLs) as a function of the cylindrical power. The in vitro optical quality of the AcrySof IQ Toric IOLs SN6AT2, SN6AT3, SN6AT4, SN6AT5 and SN6AT6 (Alcon Laboratories Inc., Forth Worth, TX, USA) was assessed with an instrument conceived for measuring Zernike's coefficients at 3.0- and 5.0-mm apertures. As a reference, the aspheric monofocal lens AcrySof IQ Aspheric SN60WF (Alcon Laboratories Inc., Forth Worth, TX, USA) was also measured. The area of visibility and cut-off frequency were used to describe the modulation transfer function (MTF) of each lens; meanwhile, the light in the bucket and the diameter of a circular area centred on the point-spread function (PSF) peak that captures 50% of the light energy were used to describe the PSF of each lens. Finally, an image simulation was computed from the Zernike values with reference purposes. Small differences were found on the metrics used for describing the MTF and PSF of the lenses at both tested apertures, but these were not statistically significant (p > 0.05). Furthermore, the image simulation showed that these differences would not have clinical relevance at all. The optical performance of the AcrySof IQ toric IOLs in terms of MTF and PSF is good and seems to be independent of the cylindrical power and similar to a non-toric aspheric lens.

Optical performance of toric intraocular lenses in the presence of decentration.

PubMed

Zhang, Bin; Ma, Jin-Xue; Liu, Dan-Yan; Du, Ying-Hua; Guo, Cong-Rong; Cui, Yue-Xian

2015-01-01

To evaluate the optical performance of toric intraocular lenses (IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned. Optical performances of toric T5 and SN60AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from 0° to 90°. The ratio of the modulation transfer function (MTF) between a decentered and a centered IOL (MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance. Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased, whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentration ratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs. Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position.

Long-Term Muscle Fatigue After Standing Work.

PubMed

Garcia, Maria-Gabriela; Läubli, Thomas; Martin, Bernard J

2015-11-01

The aims of this study were to determine long-term fatigue effects in the lower limbs associated with standing work and to estimate possible age and gender influences. The progressive accumulation of muscle fatigue effects is assumed to lead to musculoskeletal disorders, as fatigue generated by sustained low-level exertions exhibits long-lasting effects. However, these effects have received little attention in the lower limbs. Fourteen men and 12 women from two different age groups simulated standing work for 5 hr including 5-min seated rest breaks and a 30-min lunch. The younger group was also tested in a control day. Muscle fatigue was quantified by electrically induced muscle twitches (muscle twitch force [MTF]), postural stability, and subjective evaluation of discomfort. MTF showed a significant fatigue effect after standing work that persisted beyond 30 min after the end of the workday. MTF was not affected on the control day. The center of pressure displacement speed increased significantly over time after standing work but was also affected on the control day. Subjective evaluations of discomfort indicated a significant increase in perception of fatigue immediately after the end of standing work; however, this perception did not persist 30 min after. Age and gender did not influence fatigue. Objective measures show the long-term effects of muscle fatigue after 5 hr of standing work; however, this fatigue is no longer perceived after 30 min of rest postwork. The present results suggest that occupational activities requiring prolonged standing are likely to contribute to lower-extremity and/or back disorders. © 2015, Human Factors and Ergonomics Society.