Journal articles: 'Static phantom'

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Shin, Hyun Joo, Myung-Joon Kim, Choon-Sik Yoon, Kwanseop Lee, Kwan Sik Lee, Jong-Chul Park, Mi-Jung Lee, and Haesung Yoon. "Motion effects on the measurement of stiffness on ultrasound shear wave elastography: a moving liver fibrosis phantom study." Medical Ultrasonography 1, no. 1 (February 4, 2018): 14. http://dx.doi.org/10.11152/mu-1138.

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Aims: To evaluate the differences between shear wave velocities (SWVs) measured with ultrasound elastography during the continuous motion using liver fibrosis phantoms.Materials and methods: Elasticities were measured with convex and linear transducers of supersonic shear wave imaging (SSI) and acoustic radiation force impulse imaging (ARFI) using liver elasticity phantoms (3.0 and 16.9 kPa) at depths of 2, 3, 4, and 5 cm. Motion velocities were 30 and 60 rpm with the phantoms in an upright position on the Orbital shaker. To simulate different directional motion, the phantoms were laid on their side on the shaker. The values between moving and static status were compared, and the number of measurement failure was counted. Results: In SSI, the convex transducer was less affected by motion at 30 rpm with the 3 kPa phantom. In the higher velocity motion and in the higher stiffness phantom, most values from SSI were different comparing with static status, and there was a tendency for elasticity values to increase during movement. In ARFI, there were frequent measurement failures without stable results during the motion.Conclusions: Motion affected the measurement of elasticity differently in SSI and ARFI, according to the velocity, direction of the motion, and phantom stiffness. The convex transducer of SSI was less affected by motion in lower velocity motion and when using normal liver stiffness phantom.

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El-Nabulsi, Rami Ahmad. "Asymptotically Static Universe Dominated by Phantom Energy." Zeitschrift für Naturforschung A 70, no. 2 (February 1, 2015): 101–8. http://dx.doi.org/10.1515/zna-2014-0242.

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AbstractIn this article, we investigated a generalised scalar field cosmology characterised by a time-dependent coupling function, a time-dependent cosmological constant, a chameleonic field, and a time-dependent equation of state parameter. Based on a particular choice of the Hubble parameter as function of the scalar field and its time derivative, we have investigated the dynamics of the Friedmann–Robertson–Walker flat universe. We have observed that for a particular choice of the free parameters in the theory, the universe accelerates with time and asymptotically tends toward a static universe. For specific values of the free parameters, the asymptotically static universe may be dominated by phantom energy or a cosmological constant without the need to implement in the theory multiple scalar fields or additional interactions. It is also pointed out that an asymptotically static universe is as well one special class of solutions for Horndeski and generalised galileons cosmologies. Special properties and features are discussed accordingly.

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DZHUNUSHALIEV, VLADIMIR, and VLADIMIR FOLOMEEV. "4D STATIC SOLUTIONS WITH INTERACTING PHANTOM FIELDS." International Journal of Modern Physics D 17, no. 11 (October 2008): 2125–42. http://dx.doi.org/10.1142/s0218271808013753.

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Three static models with two interacting phantom and ghost scalar fields are considered: a model of a traversable wormhole, a branelike model and a spherically symmetric problem. It is shown numerically that regular solutions exist for all three cases.

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Pawel Gromek and Mariusz Nepelski. "The Methodology to Evaluate a Rescue and Training Phantom for the Road Rescuing Organized by Police Officers as Exemplified by Crash Kelly." Communications - Scientific letters of the University of Zilina 23, no. 3 (July 1, 2021): F83—F95. http://dx.doi.org/10.26552/com.c.2021.3.f83-f95.

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The paper presents a methodology to evaluate a rescue and training phantom for road rescuing organized by Police officers. The methodology is exemplified by the Crash Kelly phantom, static and dynamic functionalities of which seem to be more frequently implemented in the road safety training processes. It stems from a morphological analysis, focusing on the quality of rescue activities, emergency resources’ adequacy and the training levels. In addition, experts’ evaluation allows to examine phantoms using 6 practically determined criteria, expressing their strengths and weaknesses in analysed context. The results introduce Crash Kelly as a reference training equipment for Police officers dedicated to rescue victims after the road accidents. Basing on the research results, practical training guidelines are formulated.

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SEMİZ, İBRAHİM. "ALL "STATIC" SPHERICALLY SYMMETRIC PERFECT FLUID SOLUTIONS OF EINSTEIN'S EQUATIONS WITH CONSTANT EQUATION OF STATE PARAMETER AND FINITE POLYNOMIAL "MASS FUNCTION"." Reviews in Mathematical Physics 23, no. 08 (September 2011): 865–82. http://dx.doi.org/10.1142/s0129055x1100445x.

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We look for "static" spherically symmetric solutions of Einstein's Equations for perfect fluid source with equation of state p = wρ, for constant w. We consider all four cases compatible with the standard ansatz for the line element, discussed in previous work. For each case, we derive the equation obeyed by the mass function or its analogs. For these equations, we find all finite-polynomial solutions, including possible negative powers. For the standard case, we find no significantly new solutions, but show that one solution is a static phantom solution, another a black hole-like solution. For the dynamic and/or tachyonic cases we find, among others, dynamic and static tachyonic solutions, a Kantowski–Sachs (KS) class phantom solution, another KS-class solution for dark energy, and a second black hole-like solution. The black hole-like solutions feature segregated normal and tachyonic matter, consistent with the assertion of previous work. In the first black hole-like solution, tachyonic matter is inside the horizon, in the second, outside. The static phantom solution, a limit of an old one, is surprising at first, since phantom energy is usually associated with super-exponential expansion. The KS-phantom solution stands out since its "mass function" is a ninth order polynomial.

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Strehlow, Jan, Xu Xiao, Markus Domschke, Michael Schwenke, Ioannis Karakitsios, Senay Mihcin, Julia Schwaab, Yoav Levy, Tobias Preusser, and Andreas Melzer. "US-tracked steered FUS in a respiratory ex vivo ovine liver phantom." Current Directions in Biomedical Engineering 1, no. 1 (September 1, 2015): 294–97. http://dx.doi.org/10.1515/cdbme-2015-0073.

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AbstractOrgan motion is a major problem for Focused Ultrasound Surgery (FUS) of liver tumors. We present a liver phantom mimicking human respiratory motion (20 mm range, 3 − 7 s/cycle) and the evaluation of an ultrasound-tracked steered FUS system on that phantom. Temperature curves are recorded while sonicating in moving and static phantom. The temperature curves correlate well and show the ability of the system to compensate breathing like motion.

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Kleihaus, Burkhard, Jutta Kunz, and Eugen Radu. "Balancing a static black ring with a phantom scalar field." Physics Letters B 797 (October 2019): 134892. http://dx.doi.org/10.1016/j.physletb.2019.134892.

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Liu, Ruigang, Feng Fu, Fusheng You, Xuetao Shi, and Xiuzhen Dong. "Static imaging of the electrical impedance tomography on cylinder physical phantom." Bio-Medical Materials and Engineering 26, s1 (August 17, 2015): S1381—S1388. http://dx.doi.org/10.3233/bme-151436.

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Lazov, Boian, Petya Nedkova, and Stoytcho Yazadjiev. "Uniqueness theorem for static phantom wormholes in Einstein–Maxwell-dilaton theory." Physics Letters B 778 (March 2018): 408–13. http://dx.doi.org/10.1016/j.physletb.2018.01.059.

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Batchelor, S. "An anthropomorphic head phantom for evaluation of static and tomographic radioscintigraphy." British Journal of Radiology 58, no. 695 (November 1985): 1111–14. http://dx.doi.org/10.1259/0007-1285-58-695-1111.

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Sukupova, Lucie, Jan Rydlo, Ondrej Hlavacek, Daniel Vedlich, and Jan H. Peregrin. "Comparison of image quality of an abdominal acquisition mode of angiography systems from four major manufacturers." International Journal of Diagnostic Imaging 5, no. 2 (August 13, 2018): 6. http://dx.doi.org/10.5430/ijdi.v5n2p6.

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Objective: The aim of this study was to compare image quality of different abdominal acquisition modes under conditions simulating obese patients whose images suffer more from noise and scatter radiation. Images were acquired in clinically used acquisition modes on the static and dynamic phantom for four angiography systems.Methods: A LEGO cart with 34 cm of PMMA and Pro-RTG Fluo18 phantom were used to simulate obese patients. The low-contrast resolution was assessed subjectively by two readers and objectively using signal-difference-to-noise ratio (SDNR) and using SDNR to air kerma rate. The line-pair resolution was assessed using the transmitted contrast value for line-pair groups.Results: Systems use different exposure parameters and dose but they differ in postprocessing too. Qualitative and quantitative assessments of noise produced similar results, images produced by systems A and C were noisier than by systems B and D. Highest SDNR was provided by System B, whilst System A produced the lowest values, which were almost the same for objects with different contrast. The image quality was affected mainly by frame lengths and postprocessing, but also by the dose. The images of the static phantom were better compared to the images of the dynamic phantom, which was an expected result.Conclusions: It was possible to identify image quality differences and to characterize features of postprocessing from measurements on standardized objects. A potential for optimization on some systems was identified, although further work, including assessment of clinical images, would be needed as part of the optimization process.

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Li, Jin, Kai Lin, Hao Wen, and Wei-Liang Qian. "Gravitational Quasinormal Modes of Regular Phantom Black Hole." Advances in High Energy Physics 2017 (2017): 1–19. http://dx.doi.org/10.1155/2017/5234214.

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We investigate the gravitational quasinormal modes (QNMs) for a type of regular black hole (BH) known as phantom BH, which is a static self-gravitating solution of a minimally coupled phantom scalar field with a potential. The studies are carried out for three different spacetimes: asymptotically flat, de Sitter (dS), and anti-de Sitter (AdS). In order to consider the standard odd parity and even parity of gravitational perturbations, the corresponding master equations are derived. The QNMs are discussed by evaluating the temporal evolution of the perturbation field which, in turn, provides direct information on the stability of BH spacetime. It is found that in asymptotically flat, dS, and AdS spacetimes the gravitational perturbations have similar characteristics for both odd and even parities. The decay rate of perturbation is strongly dependent on the scale parameterb, which measures the coupling strength between phantom scalar field and the gravity. Furthermore, through the analysis of Hawking radiation, it is shown that the thermodynamics of such regular phantom BH is also influenced byb. The obtained results might shed some light on the quantum interpretation of QNM perturbation.

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Sahoo, Parbati, Annika Kirschner, and P. K. Sahoo. "Phantom fluid wormhole in f(R, T) gravity." Modern Physics Letters A 34, no. 37 (December 6, 2019): 1950303. http://dx.doi.org/10.1142/s0217732319503036.

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Wormholes (WHs) are considered as hypothetical shortcuts or tunnels in spacetime. In general relativity (GR), the fundamental ingredient of WH geometry is the presence of exotic matter at the throat, which is responsible for the violation of null energy condition (NEC). However, the modified gravity theories have shown to be able to provide WH solutions satisfying energy conditions (ECs). In this paper, we study the static spherically symmetric WH solutions in modified [Formula: see text] gravity for a phantom fluid case. The exact solutions of this model are obtained through the equation of state (EoS), [Formula: see text], associated with phantom dark energy (DE) [Formula: see text]. We find the existence of spherically symmetric WH solution supported by phantom energy distribution. The shape function of the WH obtained in this model obeys all the WH metric conditions. In modified gravity scenario, the phantom fluid WH violates the NEC in radial case, unlike in the tangential case. Furthermore, using the “volume integral quantifier” (VIQ) method, the total amount of EC violating matter in spacetime is discussed briefly.

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Richards, Michael S., Paul E. Barbone, and Assad A. Oberai. "Quantitative three-dimensional elasticity imaging from quasi-static deformation: a phantom study." Physics in Medicine and Biology 54, no. 3 (January 9, 2009): 757–79. http://dx.doi.org/10.1088/0031-9155/54/3/019.

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Muttakin, Imamul, David Abraham, Rocky Alfanz, and Rohmadi Rohmadi. "Respiration Monitoring System of Lung Phantom Using Magnetic Sensor." Bulletin of Electrical Engineering and Informatics 7, no. 1 (March 1, 2018): 15–20. http://dx.doi.org/10.11591/eei.v7i1.711.

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Monitoring vital signs is substantial in healthcare to assist both diagnosis and treatment. This work proposes a means of telemonitoring system at initial stage to observe respiratory pattern on lung phantom. Magnetic sensor module LDC1000 is used to read inductance value of conductive material in relation to distance variation. Therefore, respiration pattern can be observed. In continuous mode, the inspiration inductance value is 8 uH, while expiration is 17 uH, with stoppage is 17 uH. For static measurement, the inspiration inductance value is 7.80 uH, while expiration is 16.46 uH and stoppage is 16.46 uH. Those values could be further referred for vital signs telemonitoring system design based on contactless and portable devices.

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Schultz, Geoffrey, and Ronald Melzack. "The Charles Bonnet Syndrome: ‘Phantom Visual Images’." Perception 20, no. 6 (December 1991): 809–25. http://dx.doi.org/10.1068/p200809.

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The Charles Bonnet syndrome is a condition in which individuals experience complex visual hallucinations without demonstrable psychopathology or disturbance of normal consciousness. An analysis of the sixty-four cases described in the literature reveals that the syndrome can occur at any age though it is more common in elderly people. Reduction in vision, due to peripheral eye pathology as well as pathology within the brain, is associated with the syndrome. Individual hallucinatory episodes can last from a few seconds to most of the day. Episodes can occur for periods of time ranging from days to years, with the hallucinations changing both in frequency and in complexity during this time. The hallucinations may be triggered or stopped by a number of factors which may exert their effect through a general arousal mechanism. People, animals, buildings, and scenery are reported most often. These images may appear static, moving in the visual field, or animated. Emotional reaction to the hallucinations may be positive or negative. Several theories have been proposed to account for the hallucinations. This paper highlights the sensory deprivation framework, with particular emphasis on the activity in the visual system after sensory loss that produces patterns of nerve impulses that, in turn, give rise to visual experience.

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Daouk, J., L. Fin, P. Bailly, and M. E. Meyer. "Respiratory-gated positron emission tomography and breath-hold computed tomography coupling to reduce the influence of respiratory motion: Methodology and feasibility." Acta Radiologica 50, no. 2 (March 2009): 144–55. http://dx.doi.org/10.1080/02841850802627437.

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Background: Respiratory motion causes uptake in positron emission tomography (PET) images of chest and abdominal structures to be blurred and reduced in intensity. Purpose: To compare two respiratory-gated PET binning methods (based on frequency and amplitude analyses of the respiratory signal) and to propose a “BH-based” method based on an additional breath-hold computed tomography (CT) acquisition. Material and Methods: Respiratory-gated PET consists in list-mode (LM) acquisition with simultaneous respiratory signal recording. A phantom study featured rectilinear movement of a 0.5-ml sphere filled with 18F-fluorodeoxyglucose (18F-FDG) solution, placed in a radioactive background (sphere-to-background contrast 6:1). Two patients were also examined. Three figures of merit were calculated: the target-to-background ratio profile (TBRP) in the axial direction through the uptake (i.e., the sphere or lesion), full-width-at-half-maximum (FWHM) values, and maximized standard uptake values (SUVmax). Results: In the phantom study, the peak TBRP was 0.9 for non-gated volume, 1.83 for BH-based volume, and varied between 1.13 and 1.73 for Freq-based volumes and between 1.34 and 1.66 for Amp-based volumes. A reference volume (REF-static) was also acquired for the phantom (in a static, “expiratory” state), with a peak TBRP at 1.88. TBRPs were computed for patient data, with higher peak values for all gated volumes than for non-gated volumes. Conclusion: Respiratory-gated PET acquisition reduces the blurring effect and increases image contrast. However, Freq-based and Amp-based volumes are still influenced by inappropriate attenuation correction and misregistration of mobile lesions on CT images. The proposed BH-based method both reduces motion artifacts and improves PET-CT registration.

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Altarawneh, M. M., G. A. Alharazneh, and O. Y. Al-Madanat. "Dielectric properties of single wall carbon nanotubes-based gelatin phantoms." Journal of Advanced Dielectrics 08, no. 02 (April 2018): 1850010. http://dx.doi.org/10.1142/s2010135x18500108.

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In this work, we report the dielectric properties of Single wall Carbon Nanotubes (SWCNTs)-based phantom that is mainly composed of gelatin and water. The fabricated gelatin-based phantom with desired dielectric properties was fabricated and doped with different concentrations of SWCNTs (e.g., 0%, 0.05%, 0.10%, 0.15%, 0.2%, 0.4% and 0.6%). The dielectric constants (real [Formula: see text] and imaginary [Formula: see text] were measured at different positions for each sample as a function of frequency (0.5–20[Formula: see text]GHz) and concentrations of SWCNTs and their averages were found. The Cole–Cole plot ([Formula: see text] versus [Formula: see text] was obtained for each concentration of SWCNTs and was used to obtain the static dielectric constant [Formula: see text], the dielectric constant at the high limit of frequency [Formula: see text] and the average relaxation time [Formula: see text]. The measurements showed that the fabricated samples are in good homogeneity and the SWCNTs are dispersed well in the samples as an acceptable standard deviation is achieved. The study showed a linear increase in the static dielectric constant [Formula: see text] and invariance of the average relaxation time [Formula: see text] and the value of [Formula: see text] at room temperature for the investigated concentrations of SWCNTs.

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Noto, Kimiya, Shinichi Ueda, Hironori Kojima, Naoki Isomura, Akihiro Takemura, Shigeyuki Takamatsu, Tomoyasu Kumano, and Tsuyoshi Takanaka. "Accuracy of Dose Delivery in Multiple Breath-Hold Segmented Volumetric Modulated Arc Therapy: A Static Phantom Study." Journal of Radiotherapy 2014 (September 16, 2014): 1–5. http://dx.doi.org/10.1155/2014/743150.

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Purpose. Accuracy of dose delivery in multiple breath-hold segmented volumetric modulated arc therapy (VMAT) was evaluated in comparison to noninterrupted VMAT using a static phantom. Material and Methods. Five VMAT plans were evaluated. A Synergy linear accelerator (Elekta AB, Stockholm, Sweden) was employed. A VMAT delivery sequence was divided into multiple segments according to each of the predefined breath-hold periods (10, 15, 20, 30, and 40 seconds). The segmented VMAT delivery was compared to noninterrupted VMAT delivery in terms of the isocenter dose and pass rates of a dose difference of 1% with a dose threshold of 10% of the maximum dose on a central coronal plane using a two-dimensional dosimeter, MatriXX Evolution (IBA Dosimetry, Schwarzenbruck, Germany). Results. Means of the isocenter dose differences were 0.5%, 0.2%, 0.2%, 0.0%, and 0.0% for the beam-on-times between interrupts of 10, 15, 20, 30, and 40 seconds, respectively. Means of the pass rates were 85%, 99.9%, 100%, 100%, and 100% in the same order as the above. Conclusion. Our static phantom study indicated that the multiple breath-hold segmented VMAT maintains stable and accurate dose delivery when the beam-on-time between interrupts is 15 seconds or greater.

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Brink, Wyger M., Zhiyi Wu, and Andrew G. Webb. "A simple head-sized phantom for realistic static and radiofrequency characterization at high fields." Magnetic Resonance in Medicine 80, no. 4 (March 1, 2018): 1738–45. http://dx.doi.org/10.1002/mrm.27153.

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Nishimura, Y., M. Okubo, K. Nakamatsu, M. Okumura, T. Shibata, S. Kanamori, R. Koike, K. Hiroi, T. Nishikawa, and M. Hosono. "Static and Moving Phantom Studies for Treatment Planning in an Integrated PET/CT System." International Journal of Radiation Oncology*Biology*Physics 69, no. 3 (November 2007): S694—S695. http://dx.doi.org/10.1016/j.ijrobp.2007.07.2066.

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Kim, Deok-Hwan, Eun-Hye Yoo, Ui-Seong Hong, Jun-Hyeok Kim, Young-Heon Ko, Seung-Cheol Moon, Miju Cheon, and Jang Yoo. "Image Registration of 18F-FDG PET/CT Using the MotionFree Algorithm and CT Protocols through Phantom Study and Clinical Evaluation." Healthcare 9, no. 6 (June 4, 2021): 669. http://dx.doi.org/10.3390/healthcare9060669.

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We evaluated the benefits of the MotionFree algorithm through phantom and patient studies. The various sizes of phantom and vacuum vials were linked to RPM moving with or without MotionFree application. A total of 600 patients were divided into six groups by breathing protocols and CT scanning time. Breathing protocols were applied as follows: (a) patients who underwent scanning without any breathing instructions; (b) patients who were instructed to hold their breath after expiration during CT scan; and (c) patients who were instructed to breathe naturally. The length of PET/CT misregistration was measured and we defined the misregistration when it exceeded 10 mm. In the phantom tests, the images produced by the MotionFree algorithm were observed to have excellent agreement with static images. There were significant differences in PET/CT misregistration according to CT scanning time and each breathing protocol. When applying the type (c) protocol, decreasing the CT scanning time significantly reduced the frequency and length of misregistrations (p < 0.05). The MotionFree application is able to correct respiratory motion artifacts and to accurately quantify lesions. The shorter time of CT scan can reduce the frequency, and the natural breathing protocol also decreases the lengths of misregistrations.

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Midgley, Stewart M., Damien L. Stella, Bruce CV Campbell, Francesca Langenberg, and Paul F. Einsiedel. "CT brain perfusion: A static phantom study of contrast-to-noise ratio and radiation dose." Journal of Medical Imaging and Radiation Oncology 61, no. 3 (November 27, 2016): 361–66. http://dx.doi.org/10.1111/1754-9485.12561.

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Lee, Byung Il, Suk Hoon Oh, Eung Je Woo, Soo Yeol Lee, Min Hyoung Cho, Ohin Kwon, Jin Keun Seo, and Woon Sik Baek. "Static resistivity image of a cubic saline phantom in magnetic resonance electrical impedance tomography (MREIT)." Physiological Measurement 24, no. 2 (April 30, 2003): 579–89. http://dx.doi.org/10.1088/0967-3334/24/2/367.

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Lee, Fu-Feng, Qiong He, and Jianwen Luo. "Electromagnetic tracking-based freehand 3D quasi-static elastography with 1D linear array: a phantom study." Physics in Medicine & Biology 63, no. 24 (December 10, 2018): 245006. http://dx.doi.org/10.1088/1361-6560/aaefae.

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Arrochman, Ibnu Fajar, Dhomas Hatta Fudholi, and Yudi Prayudi. "PENGGUNAAN METODE STATIS DAN LIVE FORENSIK PADA UAV UNTUK MENDAPATKAN BUKTI DIGITAL." ILKOM Jurnal Ilmiah 11, no. 2 (August 31, 2019): 152–58. http://dx.doi.org/10.33096/ilkom.v11i2.444.152-158.

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In recent years, the use of drones by civilians is increasing rapidly by the presentation of total sales continued to increase rapidly every year. With the increasing possibility of Unmanned Aerial Vehicle (UAV) abuse, crime in the use of UAVs to be larger. Through forensic analysis of data using static forensic and live forensic to obtain data that allows it to be used as digital evidence. To dig up information that could be used as digital evidence in the UAV and controllers, as well as to know the characteristics of digital evidence on a UAV. The results showed that digital evidence on a UAV, the smartphone is used as a controller UAV has a very important role in the investigation. The findings in aircraft has a percentage of 50% and a camera memory card with 16.6%. DJI Phantom 3 Advanced GPS coordinates always store data in flight LOG; the data is always stored even when the flight mode is used does not use GPS signals to stability. Due to DJI Phantom 3 Advanced always use GPS on flights, file, image or video captured by the camera has the best GPS location coordinates to the metadata therein.

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Lee, Ho-Beom, Yong-Soo Han, and Sung-Min Kim. "Effect of Gradient Linearity and Static Magnetic Field Homogeneity on Diffusion Weighted Image: A Phantom Study." Journal of Magnetics 25, no. 2 (June 30, 2020): 157–63. http://dx.doi.org/10.4283/jmag.2020.25.2.157.

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Hyun Soo Khang, Byung Il Lee, Suk Hoon Oh, Eung Je Woo, Soo Yeol Lee, Min Hyoung Cho, Ohin Kwon, Jeong Rock Yoon, and Jin Keun Seo. "J-substitution algorithm in magnetic resonance electrical impedance tomography (MREIT): phantom experiments for static resistivity images." IEEE Transactions on Medical Imaging 21, no. 6 (June 2002): 695–702. http://dx.doi.org/10.1109/tmi.2002.800604.

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Groen, J. M., K. F. Kofoed, M. Zacho, R. Vliegenthart, T. P. Willems, and M. J. W. Greuter. "Calcium score of small coronary calcifications on multidetector computed tomography: Results from a static phantom study." European Journal of Radiology 82, no. 2 (February 2013): e58-e63. http://dx.doi.org/10.1016/j.ejrad.2012.09.018.

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Sini, Carla, Sara Broggi, Claudio Fiorino, Giovanni Mauro Cattaneo, and Riccardo Calandrino. "Accuracy of dose calculation algorithms for static and rotational IMRT of lung cancer: A phantom study." Physica Medica 31, no. 4 (June 2015): 382–90. http://dx.doi.org/10.1016/j.ejmp.2015.02.013.

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Novosyadlyj, B. "Dark Sector in Cosmology: Dark Energy on Cosmological and Astrophysical Scales." Ukrainian Journal of Physics 64, no. 11 (November 25, 2019): 998. http://dx.doi.org/10.15407/ujpe64.11.998.

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The properties and observational manifestations of the dynamical dark energy on the cosmological and astrophysical scales are discussed. We consider the dynamical dark energy in the form of quintessential and phantom scalar fields with different parameters of the equation of state and the effective sound speed. The evolution of the dynamical dark energy and its impact on the dynamics of expansion of the Universe, halos, and voids, and its behavior in the static gravitational fields of astrophysical objects are analyzed. The current state and possible tests designed to establish the nature of dark energy are highlighted.

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Сдобнов, А. Ю., В. В. Кальченко, А. В. Быков, А. П. Попов, Г. Молодый, and И. В. Меглинский. "Визуализация кровотока методом лазерных спекл-контрастных измерений в условиях неэргодичности." Журнал технической физики 128, no. 6 (2020): 773. http://dx.doi.org/10.21883/os.2020.06.49410.35-20.

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In current work, the influence of static structural inclusions in heterogeneous highly scattering media such as biotissue on the results of laser speckle contrast imaging using both temporal and spatial processing algorithms has been investigated. The applicability of laser speckle contrast imaging technique has been studied in case of non-ergodic conditions. It was shown using the phantom model that increment of amount of static scatterers comparing to the dynamic ones in tissue causes significant error in results of temporal and spatial speckle contrast processing for the given camera exposure time. At the same time, the analysis of the spatial and temporal speckle contrast values, values of coefficient of speckle dynamics as well as results of Monte Carlo simulation of sampling volumes showed that presence of relatively thin static layer (up to 30% of all volume) cannot cause significant changes in results of laser speckle contrast imaging. The camera exposure time, as well as amount of frames for image processing can vary depending on the experiment goals. Finally, the proposed spatial and temporal algorisms of laser speckle contrast imaging were verified during transcranial visualization of the mouse brain vasculature.

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Jayanthy, A. K., N. Sujatha, and M. Ramasubba Reddy. "Non-invasive assessment of static scatterer concentration in phantom body fluids using laser speckle contrast analysis technique." Optics and Lasers in Engineering 49, no. 4 (April 2011): 553–56. http://dx.doi.org/10.1016/j.optlaseng.2010.12.003.

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Rump, Jens C., Martin Jonczyk, Christian J. Seebauer, Florian Streitparth, Felix V. Güttler, Thula Walter, Bernd Hamm, and Ulf K. M. Teichgräber. "The impact of imaging speed of MR-guided punctures and interventions in static organs—A phantom study." European Journal of Radiology 80, no. 3 (December 2011): 856–60. http://dx.doi.org/10.1016/j.ejrad.2010.12.030.

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Goncharenko, Igor, Mikhail Svinin, Yutaka Kanou, and Shigeyuki Hosoe. "Predictability of Rest-to-Rest Movements in Haptic Environments with 3D Constraints." Journal of Robotics and Mechatronics 18, no. 4 (August 20, 2006): 458–66. http://dx.doi.org/10.20965/jrm.2006.p0458.

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We present a networked system with interchangeable constraints for studying skillful human movements via haptic (PHANToM-based) displays. The unified interface easily links different physical models with 2D and 3D static spatial constraints and graphical content related to the models. We analyzed motions based on data recorded by a history unit with a frequency of 100Hz. Theoretical and experimental kinematic profiles compared for several cases of basic reaching rest-to-rest tasks included curve-constrained motions with different curvatures, flexible object control, and cooperative two-arm movements. Experimental patterns exhibit the best agreement with optimal control models based on jerk and force-change minimization criteria.

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Lüghausen, Fabian, Benoit Famaey, and Pavel Kroupa. "Phantom of RAMSES (POR): A new Milgromian dynamics N-body code." Canadian Journal of Physics 93, no. 2 (February 2015): 232–41. http://dx.doi.org/10.1139/cjp-2014-0168.

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Since its first formulation in 1983, Milgromian dynamics (MOND) has been very successful in predicting the gravitational potential of galaxies from the distribution of baryons alone, including general scaling relations and detailed rotation curves of large statistical samples of individual galaxies covering a large range of masses and sizes. Most predictions, however, rely on static models, and only a handful of N-body codes have been developed over the years to investigate the consequences of the Milgromian framework for the dynamics of complex evolving dynamical systems. In this work, we present a new Milgromian N-body code, which is a customized version of the RAMSES code (R. Teyssier. Astron. Astrophys. 385, 337 (2002). doi:10.1051/0004-6361:20011817 ) and thus comes with all its features: it includes particles and gas dynamics, and importantly allows for high spatial resolution of complex systems owing to the adaptive mesh refinement technique. It further allows the direct comparison between Milgromian simulations and standard Newtonian simulations with dark matter particles. We provide basic tests of this customized code and demonstrate its performance by presenting N-body computations of dark-matter-free spherical equilibrium models as well as dark-matter-free disk galaxies in Milgromian dynamics.

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Koziol, Leo, John J. Pitre, Joseph L. Bull, Robert E. Dodde, Grant Kruger, Alan Vollmer, and William F. Weitzel. "The feasibility of using compression bioimpedance measurements to quantify peripheral edema." Journal of Electrical Bioimpedance 5, no. 1 (August 8, 2019): 99–109. http://dx.doi.org/10.5617/jeb.929.

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Abstract The accurate assessment of body fluid volume is important in many clinical situations, especially in the determination of “dry weight” in a dialysis setting. Currently, no clinically applicable diagnostic system exists to determine the mechanical properties that accurately characterize peripheral edema in an objective and quantitative manner. We have developed a method for quantifying the impact of compression on the electrical properties of tissue by measuring stress-induced changes in bioimpedance (BIS). Using this method, we simultaneously measured the impedance and mechanical response of a tissue mimicking material (tofu) under both quasi-static and dynamic loading conditions. Our results demonstrate a temporal quantification of viscoelastic properties using a viscoelastic phantom tissue model.

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Sahoo, Parbati, Barkha Taori, and K. L. Mahanta. "Mixed fluid cosmological model in f(R, T) gravity." Canadian Journal of Physics 98, no. 11 (November 2020): 1015–22. http://dx.doi.org/10.1139/cjp-2019-0494.

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We construct a locally rotationally symmetric (LRS) Bianchi type-I cosmological model in f(R, T) theory of gravity when the source of gravitation is a mixture of barotropic fluid and dark energy (DE) by employing a time-varying deceleration parameter. We observe through the behavior of the state finder parameters (r, s) that our model begins from the Einstein static era and goes to ΛCDM era. The equation of state (EOS) parameter (ωd) for DE varies from the phantom (ω < –1) phase to quintessence (ω > –1) phase, which is consistent with observational results. It is found that the discussed model can reproduce the current accelerating phase of the expansion of the universe.

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Qi-Yuan, Pan, and Jing Ji-Liang. "Late-Time Evolution of the Phantom Scalar Perturbation in the Background of a Spherically Symmetric Static Black Hole." Chinese Physics Letters 27, no. 6 (June 2010): 060302. http://dx.doi.org/10.1088/0256-307x/27/6/060302.

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Burgess, Adam. "Real and phantom risks at the petrol station: The curious case of mobile phones, fires and body static." Health, Risk & Society 9, no. 1 (March 2007): 53–66. http://dx.doi.org/10.1080/13698570601181524.

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Bronnikov, Kirill, Sergey Bolokhov, and Milena Skvortsova. "Hybrid Metric-Palatini Gravity: Regular Stringlike Configurations." Universe 6, no. 10 (October 11, 2020): 172. http://dx.doi.org/10.3390/universe6100172.

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We discuss static, cylindrically symmetric vacuum solutions of hybrid metric-Palatini gravity (HMPG), a recently proposed theory that has been shown to successfully pass the local observational tests and produce a certain progress in cosmology. We use HMPG in its well-known scalar-tensor representation. The latter coincides with general relativity containing, as a source of gravity, a conformally coupled scalar field ϕ and a self-interaction potential V(ϕ). The ϕ field can be canonical or phantom, and, accordingly, the theory splits into canonical and phantom sectors. We seek solitonic (stringlike) vacuum solutions of HMPG, that is, completely regular solutions with Minkowski metric far from the symmetry axis, with a possible angular deficit. A transition of the theory to the Einstein conformal frame is used as a tool, and many of the results apply to the general Bergmann-Wagoner-Nordtvedt class of scalar-tensor theories as well as f(R) theories of gravity. One of these results is a one-to-one correspondence between stringlike solutions in the Einstein and Jordan frames if the conformal factor that connects them is everywhere regular. An algorithm for the construction of stringlike solutions in HMPG and scalar-tensor theories is suggested, and some examples of such solutions are obtained and discussed.

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Jacobsen, S., and Y. Birkelund. "Improved Resolution and Reduced Clutter in Ultra-Wideband Microwave Imaging Using Cross-Correlated Back Projection: Experimental and Numerical Results." International Journal of Biomedical Imaging 2010 (2010): 1–10. http://dx.doi.org/10.1155/2010/781095.

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Microwave breast cancer detection is based on the dielectric contrast between healthy and malignant tissue. This radar-based imaging method involves illumination of the breast with an ultra-wideband pulse. Detection of tumors within the breast is achieved by some selected focusing technique. Image formation algorithms are tailored to enhance tumor responses and reduce early-time and late-time clutter associated with skin reflections and heterogeneity of breast tissue. In this contribution, we evaluate the performance of the so-called cross-correlated back projection imaging scheme by using a scanning system in phantom experiments. Supplementary numerical modeling based on commercial software is also presented. The phantom is synthetically scanned with a broadband elliptical antenna in a mono-static configuration. The respective signals are pre-processed by a data-adaptive RLS algorithm in order to remove artifacts caused by antenna reverberations and signal clutter. Successful detection of a 7 mm diameter cylindrical tumor immersed in a low permittivity medium was achieved in all cases. Selecting the widely used delay-and-sum (DAS) beamforming algorithm as a benchmark, we show that correlation based imaging methods improve the signal-to-clutter ratio by at least 10 dB and improves spatial resolution through a reduction of the imaged peak full-width half maximum (FWHM) of about 40–50%.

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BRONNIKOV, K. A., and OLEG B. ZASLAVSKII. "HORIZONS IN MATTER: BLACK HOLE HAIR VERSUS NULL BIG BANG." International Journal of Modern Physics D 18, no. 14 (December 31, 2009): 2283–87. http://dx.doi.org/10.1142/s0218271809015898.

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It is shown that only particular kinds of matter (in terms of the "radial" pressure-to-density ratio w) can coexist with Killing horizons in black hole or cosmological space–times. Thus, for arbitrary (not necessarily spherically symmetric) static black holes, admissible are vacuum matter (w = −1, i.e. the cosmological constant or its generalization with the same value of w) and matter with certain values of w between 0 and −1, in particular a gas of disordered cosmic strings (w = −1/3). If the cosmological evolution starts from a horizon (the so-called null big bang scenarios), this horizon can coexist with vacuum matter and certain kinds of phantom matter with w ≤ −3. It is concluded that normal matter in such scenarios is entirely created from vacuum.

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Potashov, Ivan, Julia Tchemarina, and Alexander Tsirulev. "Null and Timelike Geodesics near the Throats of Phantom Scalar Field Wormholes." Universe 6, no. 10 (October 16, 2020): 183. http://dx.doi.org/10.3390/universe6100183.

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We study geodesic motion near the throats of asymptotically flat, static, spherically symmetric traversable wormholes supported by a self-gravitating minimally coupled phantom scalar field with an arbitrary self-interaction potential. We assume that any such wormhole possesses the reflection symmetry with respect to the throat, and consider only its observable “right half”. It turns out that the main features of bound orbits and photon trajectories close to the throats of such wormholes are very different from those near the horizons of black holes. We distinguish between wormholes of two types, the first and second ones, depending on whether the redshift metric function has a minimum or maximum at the throat. First, it turns out that orbits located near the centre of a wormhole of any type exhibit retrograde precession, that is, the angle of pericentre precession is negative. Second, in the case of high accretion activity, wormholes of the first type have the innermost stable circular orbit at the throat while those of the second type have the resting-state stable circular orbit in which test particles are at rest at all times. In our study, we have in mind the possibility that the strongly gravitating objects in the centres of galaxies are wormholes, which can be regarded as an alternative to black holes, and the scalar field can be regarded as a realistic model of dark matter surrounding galactic centres. In this connection, we discuss qualitatively some observational aspects of results obtained in this article.

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Ketola, Roope, Vigyanshu Mishra, and Asimina Kiourti. "Modeling Fabric Movement for Future E-Textile Sensors." Sensors 20, no. 13 (July 3, 2020): 3735. http://dx.doi.org/10.3390/s20133735.

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Studies with e-textile sensors embedded in garments are typically performed on static and controlled phantom models that do not reflect the dynamic nature of wearables. Instead, our objective was to understand the noise e-textile sensors would experience during real-world scenarios. Three types of sleeves, made of loose, tight, and stretchy fabrics, were applied to a phantom arm, and the corresponding fabric movement was measured in three dimensions using physical markers and image-processing software. Our results showed that the stretchy fabrics allowed for the most consistent and predictable clothing-movement (average displacement of up to −2.3 ± 0.1 cm), followed by tight fabrics (up to −4.7 ± 0.2 cm), and loose fabrics (up to −3.6 ± 1.0 cm). In addition, the results demonstrated better performance of higher elasticity (average displacement of up to −2.3 ± 0.1 cm) over lower elasticity (average displacement of up to −3.8 ± 0.3 cm) stretchy fabrics. For a case study with an e-textile sensor that relies on wearable loops to monitor joint flexion, our modeling indicated errors as high as 65.7° for stretchy fabric with higher elasticity. The results from this study can (a) help quantify errors of e-textile sensors operating “in-the-wild,” (b) inform decisions regarding the optimal type of clothing-material used, and (c) ultimately empower studies on noise calibration for diverse e-textile sensing applications.

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Boye, D., O. Springer, F. Wassmer, S. Scheidegger, L. Remonda, and J. Berberat. "Effects of contour propagation and background corrections in different MRI flow software packages." Acta Radiologica Open 4, no. 6 (June 1, 2015): 205846011558912. http://dx.doi.org/10.1177/2058460115589124.

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Background Velocity-encoded magnetic resonance imaging (VENC-MRI) is a commonly used technique in cardiac examinations. This technique utilizes the phase shift properties of protons moving along a magnetic field gradient. VENC-MRI offers a unique way of measuring the severity of valve regurgitation by directly quantifying the regurgitation flow volume. Purpose To compare flow analysis results of different software programs and to assess the effect of background correction in sample patient cases. Material and Methods A phantom was built out of Polymethyl methacrylate (PMMA) which provides tubes of different diameters. These tubes can be connected to an external water circuit to generate a water flow inside the tubes. Expected absolute flow quantities inside the tubes were determined from preset tube- and flow-parameters. Different flow conditions were measured with a VENC-MRI sequence and the images evaluated using different software packages. In a second step six randomly selected patients showing different degrees of aortic insufficiency were evaluated in clinical terms. Results The contour propagation algorithms used in the software packages performed differently even on static phantom geometry. In terms of clinical evaluation the software packages performed similarly. Enabling background correction or leaving out manual correction of propagated contours changed results for severity of aortic insufficiency. Conclusion Turning on background correction and manual correction of propagated contours in MRI flow volume measurements is strongly recommended.

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Ray, Xenia, Casey Bojechko, and Kevin L. Moore. "Evaluating the sensitivity of Halcyon’s automatic transit image acquisition for treatment error detection: A phantom study using static IMRT." Journal of Applied Clinical Medical Physics 20, no. 11 (October 6, 2019): 131–43. http://dx.doi.org/10.1002/acm2.12749.

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WANG, XINGJI, and SHAN JIANG. "STUDY OF THE TARGETING ERROR FOR PERCUTANEOUS NEEDLE INSERTION INTO SOFT PHANTOM MATERIAL." Journal of Mechanics in Medicine and Biology 16, no. 02 (March 2016): 1650005. http://dx.doi.org/10.1142/s0219519416500056.

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Percutaneous needle insertion is widely used in minimally invasive procedures, in which the flexible needle is steered to reach a specific target inside the human body. The targeting error is due to a combination of flexible needle deflection and target displacement in soft tissue and only a very limited number of studies have focused on both two factors. This paper presents a targeting error calculation method which incorporates an energy-based needle deflection model into a soft tissue finite-element (FE) model. The needle insertion process is discretized into several increments on the basis of the quasi-static method. Needle deflection in each step is obtained by the needle-soft tissue interaction model which is applied into the FE model as the displacement input. A 2D-planar FE model is used to model the target displacement by imposing needle distribution forces and needle deflection at different steps on the appointed reference nodes. The soft tissue is modeled as a non-linear hyperelastic material with geometrical non-linearity. Uniaxial tensile strength tests are utilized to determine the soft tissue parameters. Needle targeting experiments are conducted to validate the simulation results. Results show that the proposed method can predict the needle targeting errors while the averaged prediction error stays below 0.4[Formula: see text]mm. At last, we conduct different experiments to compensate the obtained targeting error and thus, reaching preferable effects.

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GEOGHEGAN, PATRICK H., MARK C. JERMY, and DAVID S. NOBES. "A PIV COMPARISON OF THE FLOW FIELD AND WALL SHEAR STRESS IN RIGID AND COMPLIANT MODELS OF HEALTHY CAROTID ARTERIES." Journal of Mechanics in Medicine and Biology 17, no. 03 (July 21, 2016): 1750041. http://dx.doi.org/10.1142/s0219519417500415.

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Certain systems relevant to circulatory disease have walls which are neither rigid nor static, for example, the coronary arteries, the carotid artery and the heart chambers. In vitro modeling allows the fluid mechanics of the circulatory system to be studied without the ethical and safety issues associated with animal and human experiments. Computational methods in which the equations are coupled governing the flow and the elastic walls are maturing. Currently there is a lack of experimental data in compliant arterial systems to validate the numerical predictions. Previous experimental work has commonly used rigid wall boundaries, ignoring the effect of wall compliance. Particle Image Velocimetry is used to provide a direct comparison of both the flow field and wall shear stress (WSS) observed in experimental phantoms of rigid and compliant geometries representing an idealized common carotid artery. The input flow waveform and the mechanical response of the phantom are physiologically realistic. The results show that compliance affects the velocity profile within the artery. A rigid boundary causes severe overestimation of the peak WSS with a maximum relative difference of 61% occurring; showing compliance protects the artery from exposure to high magnitude WSS. This is important when trying to understand the development of diseases like atherosclerosis. The maximum, minimum and time averaged WSS in the rigid geometry was 2.3, 0.51 and 1.03[Formula: see text]Pa and in the compliant geometry 1.4, 0.58 and 0.84[Formula: see text]Pa, respectively.

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Caorsi, Salvatore, and Claudio Lenzi. "ANN-based radar approach to detect breast cancers in fibro-glandular tissues: numerical analysis." International Journal of Microwave and Wireless Technologies 9, no. 8 (August 22, 2017): 1597–602. http://dx.doi.org/10.1017/s1759078717000897.

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This paper presents a new artificial neural network (ANN)-based radar data processing approach for the detection of breast cancers located inside fibro-glandular tissues. The aim is not the breast imaging but detecting tumors through ANN processing of data extracted from the radar signals measured around the breast. The proposed approach has been assessed using several realistic two-dimensional breast geometries derived from the models provided by the numerical breast phantom repository of the University of Wisconsin Cross-Disciplinary Electromagnetic Laboratory (UWCEM). The pulsed radar system was assumed to operate in the mono-static configuration. The obtained results showed the abilities of the proposed approach to detect, for any single radar trace, tumors located inside the fibro-glandular tissues with a sensitivity of 93%, a specificity of 90%, and an overall accuracy of 92%.

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Journal articles on the topic 'Static phantom'

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