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Sample records for axial volumetric 320-detector

  1. Scan time and patient dose for thoracic imaging in neonates and small children using axial volumetric 320-detector row CT compared to helical 64-, 32-, and 16- detector row CT acquisitions.

    PubMed

    Kroft, Lucia J M; Roelofs, Joost J H; Geleijns, Jacob

    2010-03-01

    Recently a 320-detector-row CT (MDCT) scanner has become available that allows axial volumetric scanning of a 16-cm-long range (50 cm field of view) in a single 0.35-s rotation. For imaging neonates and small children, volume scanning is potentially of great advantage as the entire scan range can be acquired in 0.35 s, which can reduce motion artefacts and may reduce the need for sedation in clinical CT imaging. Also, because there is no over-ranging associated with axial volumetric scanning, this may reduce patient radiation dose. To evaluate, by means of a phantom study, scan time and patient dose for thoracic imaging in neonates and small children by using axial cone-beam and helical fan-beam MDCT acquisitions. Paediatric imaging protocols were assessed for a 320-MDCT volumetric scanner (Aquilion ONE, Toshiba, Otawara, Japan). The 320-MDCT scanner allows for cone-beam acquisitions with coverage up to 160 mm, but it also allows for helical fan-beam acquisitions in 64-, 32-, or 16-MDCT modes. The acquisition configurations that were evaluated were 320 x 0.5 mm, 240 x 0.5 mm, and 160 x 0.5 mm for axial volumetric scanning, and 64 x 0.5 mm, 32 x 0.5 mm, and 16 x 0.5 mm for helical scanning. Dose assessment was performed for clinically relevant paediatric angiographic or chest/mediastinum acquisition protocols with tube voltages of 80 or 100 kVp and tube currents between 40 and 80 mA. Scan time was 0.35 s for 320-MDCT acquisitions, scan times varied between 1.9 s and 8.3 s for helical acquisitions. Dose savings varying between 18% and 40% were achieved with axial volumetric scanning as compared to helical scanning (for 320- versus 64-MDCT at 160 mm and 80 kVp, and for 320- versus 16-MDCT at 80 mm and 100 kVp, respectively). Statistically significant reduction in radiation dose was found for axial 320-MDCT volumetric scanning compared to helical 64-, 32-, and 16-MDCT scanning. Axial thoracic CT of neonates and small children with volumetric 320-MDCT can be performed

  2. Patient radiation dose in prospectively gated axial CT coronary angiography and retrospectively gated helical technique with a 320-detector row CT scanner

    SciTech Connect

    Seguchi, Shigenobu; Aoyama, Takahiko; Koyama, Shuji; Fujii, Keisuke; Yamauchi-Kawaura, Chiyo

    2010-11-15

    Purpose: The aim of this study was to evaluate radiation dose to patients undergoing computed tomography coronary angiography (CTCA) for prospectively gated axial (PGA) technique and retrospectively gated helical (RGH) technique. Methods: Radiation doses were measured for a 320-detector row CT scanner (Toshiba Aquilion ONE) using small sized silicon-photodiode dosimeters, which were implanted at various tissue and organ positions within an anthropomorphic phantom for a standard Japanese adult male. Output signals from photodiode dosimeters were read out on a personal computer, from which organ and effective doses were computed according to guidelines published in the International Commission on Radiological Protection Publication 103. Results: Organs that received high doses were breast, followed by lung, esophagus, and liver. Breast doses obtained with PGA technique and a phase window width of 16% at a simulated heart rate of 60 beats per minute were 13 mGy compared to 53 mGy with RGH technique using electrocardiographically dependent dose modulation at the same phase window width as that in PGA technique. Effective doses obtained in this case were 4.7 and 20 mSv for the PGA and RGH techniques, respectively. Conversion factors of dose length product to the effective dose in PGA and RGH were 0.022 and 0.025 mSv mGy{sup -1} cm{sup -1} with a scan length of 140 mm. Conclusions: CTCA performed with PGA technique provided a substantial effective dose reduction, i.e., 70%-76%, compared to RGH technique using the dose modulation at the same phase windows as those in PGA technique. Though radiation doses in CTCA with RGH technique were the same level as, or some higher than, those in conventional coronary angiography (CCA), the use of PGA technique reduced organ and effective doses to levels less than CCA except for breast dose.

  3. CT Coronary Angiography: 256-Slice and 320-Detector Row Scanners

    PubMed Central

    Hsiao, Edward M.; Rybicki, Frank J.; Steigner, Michael

    2010-01-01

    Multidetector computed tomography (MDCT) has rapidly evolved from 4-detector row systems in 1998 to 256-slice and 320-detector row CT systems. With smaller detector element size and faster gantry rotation speed, spatial and temporal resolution of the 64-detector MDCT scanners have made coronary artery imaging a reliable clinical test. Wide-area coverage MDCT, such as the 256-slice and 320-detector row MDCT scanners, has enabled volumetric imaging of the entire heart free of stair-step artifacts at a single time point within one cardiac cycle. It is hoped that these improvements will be realized with greater diagnostic accuracy of CT coronary angiography. Such scanners hold promise in performing a rapid high quality “triple rule-out” test without high contrast load, improved myocardial perfusion imaging, and even four-dimensional CT subtraction angiography. These emerging technical advances and novel applications will continue to change the way we study coronary artery disease beyond detecting luminal stenosis. PMID:20425186

  4. Diagnostic performance of 320-detector CT coronary angiography in patients with atrial fibrillation: preliminary results.

    PubMed

    Xu, Lei; Yang, Lin; Fan, Zhanming; Yu, Wei; Lv, Biao; Zhang, Zhaoqi

    2011-05-01

    To evaluate the feasibility, diagnostic accuracy, and radiation dose of CT coronary angiography (CTCA) in patients with atrial fibrillation (AF) using 320-detector CT. Thirty-seven patients with persistent AF and suspected coronary artery disease (CAD) were enrolled. All patients underwent both 320-detector CTCA and conventional coronary angiography (CCA). CT image quality and the presence of significant (≥ 50%) stenosis were evaluated by two radiologists blinded to the results of CCA. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated using CCA as the reference standard. Differences in detection of coronary artery stenosis between 320-detector CTCA and CCA were evaluated with McNemar's test. Patient radiation dose was calculated by multiplying dose length product by conversion coefficient of 0.017. In total 474 evaluated coronary segments, 459 (96.8%) segments were diagnostically evaluable. On per-segment analysis, sensitivity, specificity, PPV and NPV were 90.0% (18 of 20), 99.3% (436 of 439), 85.7% (18 of 21) and 99.5% (436 of 438). No significant difference was found between 320-detector CTCA and CCA on the detection of significant stenosis (P = 1.000). Effective doses of 320-detector CTCA was 13.0 ± 4.7 mSv. 320-detector CTCA is feasible and accurate in excluding CAD in patients with AF.

  5. SimDoseCT: dose reporting software based on Monte Carlo simulation for a 320 detector-row cone-beam CT scanner and ICRP computational adult phantoms

    NASA Astrophysics Data System (ADS)

    Cros, Maria; Joemai, Raoul M. S.; Geleijns, Jacob; Molina, Diego; Salvadó, Marçal

    2017-08-01

    This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT

  6. SimDoseCT: dose reporting software based on Monte Carlo simulation for a 320 detector-row cone-beam CT scanner and ICRP computational adult phantoms.

    PubMed

    Cros, Maria; Joemai, Raoul M S; Geleijns, Jacob; Molina, Diego; Salvadó, Marçal

    2017-07-17

    This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT

  7. Diagnostic accuracy of noninvasive coronary angiography with 320-detector row computed tomography.

    PubMed

    Nasis, Arthur; Leung, Michael C; Antonis, Paul R; Cameron, James D; Lehman, Sam J; Hope, Sarah A; Crossett, Marcus P; Troupis, John M; Meredith, Ian T; Seneviratne, Sujith K

    2010-11-15

    We sought to evaluate the diagnostic accuracy of noninvasive coronary angiography using 320-detector row computed tomography, which provides 16-cm craniocaudal coverage in 350 ms and can image the entire coronary tree in a single heartbeat, representing a significant advance from previous-generation scanners. We evaluated 63 consecutive patients who underwent 320-detector row computed tomography and invasive coronary angiography for the investigation of suspected coronary artery disease. Patients with known coronary artery disease were excluded. Computed tomographic (CT) studies were assessed by 2 independent observers blinded to results of invasive coronary angiography. A single observer unaware of CT results assessed invasive coronary angiographic images quantitatively. All available coronary segments were included in the analysis, regardless of size or image quality. Lesions with >50% diameter stenoses were considered significant. Mean heart rate was 63 ± 7 beats/min, with 6 patients (10%) in atrial fibrillation during image acquisition. Thirty-three patients (52%) and 70 of 973 segments (7%) had significant coronary stenoses on invasive coronary angiogram. Seventeen segments (2%) were nondiagnostic on computed tomogram and were assumed to contain significant stenoses on an "intention-to-diagnose" analysis. Sensitivity, specificity, and positive and negative predictive values of computed tomography for detecting significant stenoses were 94%, 87%, 88%, and 93%, respectively, by patient (n = 63), 89%, 95%, 82%, and 97%, respectively, by artery (n = 260), and 87%, 97%, 73%, and 99%, respectively, by segment (n = 973). In conclusion, noninvasive 320-detector row CT coronary angiography provides high diagnostic accuracy across all coronary segments, regardless of size, cardiac rhythm, or image quality.

  8. High-speed axial-scanning wide-field microscopy for volumetric particle tracking velocimetry

    NASA Astrophysics Data System (ADS)

    Chen, T.-H.; Ault, J. T.; Stone, H. A.; Arnold, C. B.

    2017-05-01

    The ability to understand and visualize complex flow structures in microfluidic and biological systems relies heavily on the resolving power of three-dimensional (3D) particle velocimetry techniques. We propose a simple technique for acquiring volumetric particle information with the potential for microsecond time resolution. By utilizing a fast varifocal lens in a modified wide-field microscope, we capture both volumetric and planar information with microsecond time resolution. The technique is demonstrated by tracking particle motions in the complex, three-dimensional flow in a high Reynolds number laminar flow at a branching arrow-shaped junction.

  9. Influence of 320-detector-row volume scanning and AAPM report 111 CT dosimetry metrics on size-specific dose estimate: a Monte Carlo study.

    PubMed

    Haba, Tomonobu; Koyama, Shuji; Kinomura, Yutaka; Ida, Yoshihiro; Kobayashi, Masanao

    2016-09-01

    The American Association of Physicists in Medicine (AAPM) task group 204 has recommended the use of size-dependent conversion factors to calculate size-specific dose estimate (SSDE) values from volume computed tomography dose index (CTDIvol) values. However, these conversion factors do not consider the effects of 320-detector-row volume computed tomography (CT) examinations or the new CT dosimetry metrics proposed by AAPM task group 111. This study aims to investigate the influence of these examinations and metrics on the conversion factors reported by AAPM task group 204, using Monte Carlo simulations. Simulations were performed modelling a Toshiba Aquilion ONE CT scanner, in order to compute dose values in water for cylindrical phantoms with 8-40-cm diameters at 2-cm intervals for each scanning parameter (tube voltage, bow-tie filter, longitudinal beam width). Then, the conversion factors were obtained by applying exponential regression analysis between the dose values for a given phantom diameter and the phantom diameter combined with various scanning parameters. The conversion factors for each scanning method (helical, axial, or volume scanning) and CT dosimetry method (i.e., the CTDI100 method or the AAPM task group 111 method) were in agreement with those reported by AAPM task group 204, within a percentage error of 14.2 % for phantom diameters ≥11.2 cm. The results obtained in this study indicate that the conversion factors previously presented by AAPM task group 204 can be used to provide appropriate SSDE values for 320-detector-row volume CT examinations and the CT dosimetry metrics proposed by the AAPM task group 111.

  10. Clinical indications and utilization of 320-detector row CT in 2500 outpatients.

    PubMed

    Tabibian, Benjamin; Roach, Cayce J; Hanson, Eric H; Wynn, Brad L; Orrison, William W

    2011-06-01

    Clinical indications and utilization patterns for 3963 CT scans on 2500 consecutive patents on a 320-detector row CT in an outpatient setting were retrospectively analyzed and compared with previously reported CT studies. The impact of the latest generation CT technology, including whole organ perfusion, on indications and utilization patterns during the study period was also assessed. The top five requested CT scan types were abdomen/pelvis, chest, head, sinuses, and coronary CT angiography. Indication and utilization rates were similar to prior studies for abdomen/pelvis, non-cardiac chest, and head CT scans. Abdominal pain and headaches were the most frequent indications for abdomen/pelvis and head CTs, respectively. The 7.3% cardiac CT scan utilization rate was not comparable to rates of up to 72% in self-referral outpatient settings. Whole organ volume CT imaging was utilized in 100% of coronary CT angiography and 22.7% of head CTs. The 320-row CT had fewer negative head and body CT findings as compared to prior reports. The availability of new technology, such as whole organ dynamic scans, appears to have influenced CT indications, utilization and finding rates with a decrease in negative brain and body results. Comparisons with previous outpatient CT studies were similar for multiple categories with the exception of cardiac CT utilization, which is heavily influenced by self-referral. Further study of outpatient imaging indications and utilization rates from multiple centers may benefit from a standardized categorization to improve understanding of the disparate outpatient imaging environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Impact of heart rate on diagnostic accuracy of second generation 320-detector computed tomography coronary angiography.

    PubMed

    Nerlekar, Nitesh; Ko, Brian S; Nasis, Arthur; Cameron, James D; Leung, Michael; Brown, Adam J; Wong, Dennis T L; Ngu, Philip J; Troupis, John M; Seneviratne, Sujith K

    2017-06-01

    To assess the impact of elevated heart rate (HR) on the diagnostic accuracy and image quality of second-generation 320-detector computed tomography coronary angiography (320-CTCA). Consecutive patients with suspected coronary disease referred for invasive coronary angiography (ICA) were prospectively recruited and underwent 320-CTCA. Pre-scan beta-blockers were administered if native HR>80 bpm and post-scan cohorts stratified by traditional (HR ≤60 bpm) and elevated HR (61-80 bpm). A wider phase window was used for the elevated HR group (30-80%). 320-CTCA and ICA were analyzed by independent readers blinded to other data. Significant disease was defined as ≥50% visual stenosis on ICA. Uninterpretable segments by 320-CTCA were considered to be significant on an intention-to-diagnose principle. Image quality was assessed by 5-point Likert score. Of 107 patients studied (1,662 segments), there was no significant difference in sensitivity, specificity, positive and negative predictive value between patients with HR ≤60 bpm (n=55) vs. HR 61-80 bpm (n=52): 97%, 88%, 95%, 94% vs. 100%, 88%, 95%, 100%; Receiver operator characteristic-area under the curve 0.93 vs. 0.94, P=0.82). Overall per-patient diagnostic accuracy was 96% in both groups with no significant difference in interpretable segments (Likert ≥2) or median radiation dose (2.4 mSv vs. 2.7 mSv, P=0.35). Only 4/1,662 (0.2%) segments were uninterpretable by motion artefact in the whole cohort. In patients with HR >60 and up to 80bpm, second generation 320-CTCA provides comparably adequate diagnostic accuracy to HR ≤60 without significantly impacting upon overall segmental evaluability.

  12. Computed tomography dose assessment for a 160 mm wide, 320 detector row, cone beam CT scanner.

    PubMed

    Geleijns, J; Salvadó Artells, M; de Bruin, P W; Matter, R; Muramatsu, Y; McNitt-Gray, M F

    2009-05-21

    Computed tomography (CT) dosimetry should be adapted to the rapid developments in CT technology. Recently a 160 mm wide, 320 detector row, cone beam CT scanner that challenges the existing Computed Tomography Dose Index (CTDI) dosimetry paradigm was introduced. The purpose of this study was to assess dosimetric characteristics of this cone beam scanner, to study the appropriateness of existing CT dose metrics and to suggest a pragmatic approach for CT dosimetry for cone beam scanners. Dose measurements with a small Farmer-type ionization chamber and with 100 mm and 300 mm long pencil ionization chambers were performed free in air to characterize the cone beam. According to the most common dose metric in CT, namely CTDI, measurements were also performed in 150 mm and 350 mm long CT head and CT body dose phantoms with 100 mm and 300 mm long pencil ionization chambers, respectively. To explore effects that cannot be measured with ionization chambers, Monte Carlo (MC) simulations of the dose distribution in 150 mm, 350 mm and 700 mm long CT head and CT body phantoms were performed. To overcome inconsistencies in the definition of CTDI100 for the 160 mm wide cone beam CT scanner, doses were also expressed as the average absorbed dose within the pencil chamber (D100). Measurements free in air revealed excellent correspondence between CTDI300air and D100air, while CTDI100air substantially underestimates CTDI300air. Results of measurements in CT dose phantoms and corresponding MC simulations at centre and peripheral positions were weighted and revealed good agreement between CTDI300w, D100w and CTDI600w, while CTDI100w substantially underestimates CTDI300w. D100w provides a pragmatic metric for characterizing the dose of the 160 mm wide cone beam CT scanner. This quantity can be measured with the widely available 100 mm pencil ionization chamber within 150 mm long CT dose phantoms. CTDI300w measured in 350 mm long CT dose phantoms serves as an appropriate standard of

  13. Quantification of radiation dose reduction by reducing z-axis coverage in 320-detector coronary CT angiography.

    PubMed

    Murphy, David J; Keraliya, Abhishek; Himes, Nathan; Aghayev, Ayaz; Blankstein, Ron; Steigner, Michael L

    2017-08-01

    To quantify the radiation dose reduction achievable by minimizing z-axis coverage in 320-detector coronary CT angiography (CCTA). We retrospectively reviewed 130 CCTAs performed on 320-detector CT that offers up to 16 cm z-axis coverage (adjustable in 2-cm increments), allowing complete coverage of the heart in a single gantry rotation. For each CT, we obtained the radiation dose [CT dose index and dose-length product (DLP)], measured the z-axis field of view and measured the craniocaudal cardiac size (distance from the left main coronary artery to the cardiac apex). We calculated the radiation dose savings achievable by reducing the z-axis coverage to the minimum necessary to cover the heart using 320 × 0.5-mm (maximum 16 cm) and 256 × 0.5-mm (maximum 12.8 cm) detector collimations. Results are expressed as mean ± standard deviation. The mean craniocaudal cardiac size was 10.5 ± 1.0 cm, with 85% (n = 112) of CCTAs performed with 16 cm of z-axis coverage. The mean DLP was 417.6 ± 182.4 mGy cm, with the mean DLP saving achievable using the minimum z-axis coverage required to completely image the heart being 96.2 ± 47.4 mGy cm, an average dose reduction of 26.9 ± 7.0%. z-axis coverage of ≤12 cm was adequate for 92% and 12.8 cm for 98% of subjects. Using the minimal z-axis coverage to adequately image the heart is a simple step that can reduce the DLP in 320-detector CCTA by approximately 27%. z-axis coverage of ≤12 cm is adequate for 92%, 12.8 cm for 98% and 14 cm for 100% of patients undergoing CCTA. Advances in knowledge: Reducing z-axis coverage in 320-detector CCTA can reduce DLP by approximately 27%.

  14. Superior CT coronary angiography image quality at lower radiation exposure with second generation 320-detector row CT in patients with elevated heart rate: a comparison with first generation 320-detector row CT

    PubMed Central

    Soh, Siang Y.; Ko, Brian S. H.; Cameron, James D.; Crossett, Marcus; Nasis, Arthur; Troupis, John; Meredith, Ian T.; Seneviratne, Sujith K.

    2014-01-01

    Background This study aims to compare the image quality of second generation versus first generation 320-computed tomography coronary angiography (CTCA) in patients with heart rate ≥65 bpm as it has not been specifically reported. Methods Consecutive patients who underwent CTCA using second-generation-320-detector-row-CT were prospectively enrolled. A total of 50 patients with elevated (≥65 bpm) heart rate and 50 patients with controlled (<65 bpm) heart rate were included. Age and gender matched patients who were scanned with the first-generation-320-detector-row-CT were retrospectively identified. Image quality in each coronary artery segment was assessed by two blinded CT angiographers using the five-point Likert scale. Results In the elevated heart rate cohorts, while there was no significant difference in heart rate during scan-acquisition (66 vs. 69 bpm, P=0.308), or body mass index (28.5 vs. 29.6, P=0.464), the second generation scanner was associated with better image quality (3.94±0.6 vs. 3.45±0.8, P=0.001), and with lower radiation (2.8 vs. 4.3 mSv, P=0.009). There was no difference in scan image quality for the controlled heart rate cohorts. Conclusions The second generation CT scanner provides better image quality at lower radiation dose in patients with elevated heart rate (≥65 bpm) compared to first generation CT scanner. PMID:25276615

  15. Radiation dose assessment in a 320-detector-row CT scanner used in cardiac imaging

    SciTech Connect

    Goma, Carles; Ruiz, Agustin; Jornet, Nuria; Latorre, Artur; Pallerol, Rosa M.; Carrasco, Pablo; Eudaldo, Teresa; Ribas, Montserrat

    2011-03-15

    Purpose: In the present era of cone-beam CT scanners, the use of the standardized CTDI{sub 100} as a surrogate of the idealized CTDI is strongly discouraged and, consequently, so should be the use of the dose-length product (DLP) as an estimate of the total energy imparted to the patient. However, the DLP is still widely used as a reference quantity to normalize the effective dose for a given scan protocol mainly because the CTDI{sub 100} is an easy-to-measure quantity. The aim of this article is therefore to describe a method for radiation dose assessment in large cone-beam single axial scans, which leads to a straightforward estimation of the total energy imparted to the patient. The authors developed a method accessible to all medical physicists and easy to implement in clinical practice in an attempt to update the bridge between CT dosimetry and the estimation of the effective dose. Methods: The authors used commercially available material and a simple mathematical model. The method described herein is based on the dosimetry paradigm introduced by the AAPM Task Group 111. It consists of measuring the dose profiles at the center and the periphery of a long body phantom with a commercial solid-state detector. A weighted dose profile is then calculated from these measurements. To calculate the CT dosimetric quantities analytically, a Gaussian function was fitted to the dose profile data. Furthermore, the Gaussian model has the power to condense the z-axis information of the dose profile in two parameters: The single-scan central dose, f(0), and the width of the profile, {sigma}. To check the energy dependence of the solid-state detector, the authors compared the dose profiles to measurements made with a small volume ion chamber. To validate the overall method, the authors compared the CTDI{sub 100} calculated analytically to the measurement made with a 100 mm pencil ion chamber. Results: For the central and weighted dose profiles, the authors found a good

  16. Overbeaming and overlapping of volume-scan CT with tube current modulation in a 320-detector row CT scanner

    NASA Astrophysics Data System (ADS)

    Liao, Ying-Lan; Chen, Yan-Shi; Lai, Nan-Ku; Chuang, Keh-Shih; Tsai, Hui-Yu

    2014-11-01

    The purpose of this study was to evaluate the performance of volume scan tube current modulation (VS-ATCM) with adaptive iterative dose reduction 3D (AIDR3D) technique in abdomen CT examinations. We scanned an elliptical cone-shaped phantom utilizing AIDR3D technique combined with VS-ATCM mode in a 320-detector row CT scanner. The image noise distributions with conventional filtered back-projction (FBP) technique and those with AIDR3D technique were compared. The radiation dose profile and tube current time product (mAs) in three noise levels of VS-ATCM modes were compared. The radiation beam profiles of five preset scan lengths were measured using Gafchromic film strips to assess the effects of overbeaming and everlapping. The results indicated that the image noises with AIDR3D technique was 13-74% lower than those in FBP technique. The mAs distributions can be a prediction for various abdominal sizes when undergoing a VS-ATCM mode scan. Patients can receive the radiation dose of overbeaming and overlapping during the VS-ATCM mode scans.

  17. Radiation dose reduction for coronary artery calcium scoring at 320-detector CT with adaptive iterative dose reduction 3D.

    PubMed

    Tatsugami, Fuminari; Higaki, Toru; Fukumoto, Wataru; Kaichi, Yoko; Fujioka, Chikako; Kiguchi, Masao; Yamamoto, Hideya; Kihara, Yasuki; Awai, Kazuo

    2015-06-01

    To assess the possibility of reducing the radiation dose for coronary artery calcium (CAC) scoring by using adaptive iterative dose reduction 3D (AIDR 3D) on a 320-detector CT scanner. Fifty-four patients underwent routine- and low-dose CT for CAC scoring. Low-dose CT was performed at one-third of the tube current used for routine-dose CT. Routine-dose CT was reconstructed with filtered back projection (FBP) and low-dose CT was reconstructed with AIDR 3D. We compared the calculated Agatston-, volume-, and mass scores of these images. The overall percentage difference in the Agatston-, volume-, and mass scores between routine- and low-dose CT studies was 15.9, 11.6, and 12.6%, respectively. There were no significant differences in the routine- and low-dose CT studies irrespective of the scoring algorithms applied. The CAC measurements of both imaging modalities were highly correlated with respect to the Agatston- (r = 0.996), volume- (r = 0.996), and mass score (r = 0.997; p < 0.001, all); the Bland-Altman limits of agreement scores were -37.4 to 51.4, -31.2 to 36.4 and -30.3 to 40.9%, respectively, suggesting that AIDR 3D was a good alternative for FBP. The mean effective radiation dose for routine- and low-dose CT was 2.2 and 0.7 mSv, respectively. The use of AIDR 3D made it possible to reduce the radiation dose by 67% for CAC scoring without impairing the quantification of coronary calcification.

  18. Preliminary Study of Prospective ECG-Gated 320-Detector CT Coronary Angiography in Patients with Ventricular Premature Beats

    PubMed Central

    Wang, Wei; Wang, Dan; Shen, Baozhong

    2012-01-01

    Background To study the applicability of prospective ECG-gated 320-detector CT coronary angiography (CTCA) in patients with ventricular premature beats(VPB), and determine the scanning mode that best maximizes image quality and reduces radiation dose. Methods: 110 patients were divided into a VPB group (60 cases) and a control group (50 cases) using CTCA.All the patients then underwent coronary angiography (CAG) within one month. CAG served as a reference standard through which the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTCA in diagnosing significant coronary artery stenosis (luminal stenosis ≥50%) could be analyzed. The two radiologists with more than 3 years’ experience in cardiac CT each finished the image analysis after consultation. A personalized scanning mode was adopted to compare image quality and radiation dose between the two groups. Methodology/Principal Findings At the coronary artery segment level, sensitivity, specificity, PPV, and NPV in the premature beat group were 92.55%, 98.21%, 88.51%, and 98.72% respectively. In the control group these values were found to be 95.79%, 98.42%, 90.11%, and 99.28% respectively. Between the two groups, specificity, sensitivity PPV, NPV was no significant difference. The two groups had no significant difference in image quality score (P>0.05). Heart rate (77.20±12.07 bpm) and radiation dose (14.62±1.37 mSv) in the premature beat group were higher than heart rate (58.72±4.73 bpm) and radiation dose (3.08±2.35 mSv) in the control group. In theVPB group, the radiation dose (34.55±7.12 mSv) for S-field scanning was significantly higher than the radiation dose (15.10±1.12 mSv) for M-field scanning. Conclusions/Significance With prospective ECG-gated scanning for VPB, the diagnostic accuracy of coronary artery stenosis is very high. Scanning field adjustment can reduce radiation dose while maintaining good image quality. For patients with slow heart

  19. Assessment of left ventricular volumes, ejection fraction and regional wall motion with retrospective electrocardiogram triggered 320-detector computed tomography: a comparison with 2D-echocardiography.

    PubMed

    Nasis, Arthur; Moir, Stuart; Seneviratne, Sujith K; Cameron, James D; Mottram, Philip M

    2012-04-01

    Left ventricular (LV) volumes, ejection fraction (LVEF) and regional wall motion (LVRWM) have important treatment and prognostic implications in patients with coronary artery disease. We sought to determine the accuracy of 320-row multidetector computed tomography (MDCT) for the assessment of LV volumes, LVEF and LVRWM, using 2D-echocardiography as the reference standard. We evaluated 50 consecutive patients (mean age 60 ± 14 years, 66% male) who underwent 320-detector MDCT (dose-modulated retrospective electrocardiogram-triggering) and 2D-echocardiography within 14 days for investigation of known or suspected coronary artery disease. Two blinded readers measured LV volumes on MDCT and visually assessed LVRWM with a 3-point scale using a 17-segment model. A separate experienced echocardiologist, blinded to MDCT findings, assessed LVRWM on 2D-echocardiograms and determined LV volumes and LVEF using Simpson's biplane method. 2D-echocardiography served as the reference standard. Mean LVEF was 59 ± 9% (range 26-75%) on 2D-echocardiography and 60 ± 9% (range 27-76%) on MDCT. Using linear regression analysis, MDCT agreed very well with 2D-echocardiography for assessment of LVEDV (r(2) = 0.88; P < 0.001), LVESV (r(2) = 0.95; P < 0.001) and LVEF (r(2) = 0.90; P < 0.001). Mean differences (±standard deviation) of 14 ± 13 ml, 5 ± 7 ml and 1 ± 3% were observed between MDCT and 2D-echocardiography for LVEDV, LVESV and LVEF, respectively. On 2D-echocardiography, 81/850 (9.5%) segments had abnormal LVRWM. Agreement for assessment of LVRWM between 2D-echocardiography and MDCT was excellent (96%, k = 0.76). Accurate assessment of LV volumes, LVEF and LVRWM is feasible with 320-detector MDCT, with MDCT demonstrating slightly larger LV volumes than 2D-echocardiography.

  20. Assessment of Renal Function in Patients with Unilateral Ureteral Obstruction Using Whole-Organ Perfusion Imaging with 320-Detector Row Computed Tomography

    PubMed Central

    Yu, Juan; Feng, You-Zhen; Xian, Zhao-Hui; Yang, Wen-Cai; Mo, Xu-Kai

    2015-01-01

    Background Obstructed nephropathy is a common complication of several disease processes. Accurate evaluation of the functional status of the obstructed kidney is important to achieve a good outcome. The purpose of this study was to investigate renal cortical and medullary perfusion changes associated with unilateral ureteral obstruction (UUO) using whole-organ perfusion imaging with 320-detector row computed tomography (CT). Methodology/Principle Findings Sixty-four patients with UUO underwent whole-organ CT perfusion imaging. Patients were divided into 3 groups, mild, moderate, and severe, based on hydronephrosis severity. Twenty sex- and age-matched patients without renal disease, who referred to abdominal CT, were chosen as control subjects. Mean cortical and medullary perfusion parameters of obstructed and contralateral kidneys were compared, and mean perfusion ratios between obstructed and contralateral kidneys were calculated and compared. Mean cortical or medullary blood flow (BF) and blood volume (BV) of the obstructed kidneys in the moderate UUO and BF, BV, and clearance (CL) in the severe UUO were significantly lower than those of the contralateral kidneys (p < 0.05). The mean cortical or medullary BF of the obstructed kidney in the moderate UUO, and BF, BV, and CL in the severe UUO were significantly lower than those of the kidneys in control subjects (p < 0.05). Mean cortical or medullary BF of the non-obstructed kidneys in the severe UUO were statistically greater than that of normal kidneys in control subjects (p < 0.05). An inverse correlation was observed between cortical and medullary perfusion ratios and grades of hydronephosis (p < 0.01). Conclusions/Significance Perfusion measurements of the whole kidney can be obtained with 320-detector row CT, and estimated perfusion ratios have potential for quantitatively evaluating UUO renal injury grades. PMID:25874690

  1. Impact of reduced-radiation dual-energy protocols using 320-detector row computed tomography for analyzing urinary calculus components: initial in vitro evaluation.

    PubMed

    Cai, Xiangran; Zhou, Qingchun; Yu, Juan; Xian, Zhaohui; Feng, Youzhen; Yang, Wencai; Mo, Xukai

    2014-10-01

    To evaluate the impact of reduced-radiation dual-energy (DE) protocols using 320-detector row computed tomography on the differentiation of urinary calculus components. A total of 58 urinary calculi were placed into the same phantom and underwent DE scanning with 320-detector row computed tomography. Each calculus was scanned 4 times with the DE protocols using 135 kV and 80 kV tube voltage and different tube current combinations, including 100 mA and 570 mA (group A), 50 mA and 290 mA (group B), 30 mA and 170 mA (group C), and 10 mA and 60 mA (group D). The acquisition data of all 4 groups were then analyzed by stone DE analysis software, and the results were compared with x-ray diffraction analysis. Noise, contrast-to-noise ratio, and radiation dose were compared. Calculi were correctly identified in 56 of 58 stones (96.6%) using group A and B protocols. However, only 35 stones (60.3%) and 16 stones (27.6%) were correctly diagnosed using group C and D protocols, respectively. Mean noise increased significantly and mean contrast-to-noise ratio decreased significantly from groups A to D (P <.05). In addition, the effective dose decreased markedly from groups A to D at 3.78, 1.81, 1.07, and 0.37 mSv, respectively. Decreasing the DE tube currents from 100 mA and 570 mA to 50 mA and 290 mA resulted in 96.6% accuracy for urinary calculus component analysis while reducing patient radiation exposure to 1.81 mSv. Further reduction of tube currents may compromise diagnostic accuracy. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Non-invasive evaluation of internal thoracic artery anastomosed to the left anterior descending artery with 320-detector row computed tomography and adenosine thallium-201 myocardial perfusion scintigraphy.

    PubMed

    Takagi, Yasushi; Akita, Kiyotoshi; Kondo, Hiroshi; Ishida, Michiko; Kaneko, Kan; Sato, Masato; Ando, Motomi

    2012-01-01

    We evaluated the relationship between internal thoracic artery (ITA) stenosis anastomosed to the left anterior descending artery (LAD) and the degree of LAD stenosis using 320-detector row computed tomography (320-ADCT) and adenosine thallium-201 myocardial perfusion scintigraphy (Tl-201-MPS). We included 101 patients who underwent coronary artery bypass grafting (CABG) using ITA grafts; 320-ADCT and adenosine Tl-201-MPS were performed 2-3 months after CABG. Clinical parameters, degree of LAD stenosis, and regional myocardial ischemia of the LAD territory were compared between patients without ITA stenosis (Group A) and with ITA stenosis (Group B). Thirty patients (30%) had ≤75% LAD stenosis, and 9 patients (30%) showed significant ITA stenosis. Regional ischemia was noted in 23 patients (23%). There were no differences in clinical parameters between the 2 groups. Twenty-two patients (24%) in Group A and 8 patients (89%) in Group B had ≤75% LAD stenosis (P <0.002). No Group B patients had regional myocardial ischemia of the LAD territory. We concluded that ≤75% LAD stenosis significantly influences ITA stenosis, without associated regional myocardial ischemia of the LAD territory. Non-invasive 320-ADCT and adenosine Tl-201-MPS for ITA evaluation may be useful for long-term follow-up of patients after CABG.

  3. The evolution and investigation of native coronary arteries in patients after coronary stent implantation: a study by 320-detector CT angiography.

    PubMed

    Juan, Yu-Hsiang; Huang, Yu-Chieh; Sun, Zhonghua; Hsieh, I-Chang; Chan, Wen-Hui; Chen, Chun-Chi; Hung, Kuo-Chun; Wen, Ming-Shien; Wan, Yung-Liang

    2014-06-01

    To study the role of 320-detector coronary computed tomography angiography (CTA) in assessing native coronary arteries in patients treated with coronary stents. 123 patients with coronary stenting received both CTA and conventional coronary angiography (CCA) within 1 day. The clinical parameters, coronary calcium scoring, CTA and CCA were analyzed to determine the prevalence of significant stenosis of native coronary arteries (SSNCA), the predictive value of CTA and the factors correlating with SSNCA and newly developed SSNCA after stenting (NDSSNCAS), with CCA as the standard of reference, using both vessel-based analysis (VBA) and patient-based analysis (PBA). Both the source and the reconstructed images were analyzed by CTA. All native coronary arteries were interpretable independent of cardiac motion. CTA showed a sensitivity/specificity of 93.5%/97.3% and 92.5%/92.5% in diagnosing SSNCA in VBA and PBA, respectively. The significant factors related to SSNCA were higher calcium scores (P = 0.003), a higher serum glucose level (P = 0.048), a greater number of vessels without previous stent placement (P = 0.003) and fewer stents implanted within the vessels (P = 0.003). The risk factors showed no significant correlation from PBA on SSNCA or from NDSSNCAS on either VBA or PBA. CTA demonstrates excellent correlation with CCA. The prevalence of SSNCA is significantly correlated with the presence of higher calcium scores in the arteries, a higher serum glucose level, a greater number of vessels without previous stent placement and fewer stents implanted within the vessels; PBA on SSNCA and NDSSNCAS on both VBA and PBA showed no significance.

  4. Whole brain CT perfusion deficits using 320-detector-row CT scanner in TIA patients are associated with ABCD2 score.

    PubMed

    Mehta, Bijal K; Mustafa, Ghulam; McMurtray, Aaron; Masud, Mohammed W; Gunukula, Sameer K; Kamal, Haris; Kandel, Amit; Beltagy, Abdelrahman; Li, Ping

    2014-01-01

    Transient ischemic attacks (TIA) are cerebral ischemic events without infarction. The uses of CT perfusion (CTP) techniques such as cerebral blood volume (CBV), time to peak (TTP), mean transit time (MTT) and cerebral blood flow (CBF) provide real time data about ischemia. It has been shown that CTP changes occur in less sensitive CTP scanners in patients with TIA. Larger detector row CTP (whole brain perfusion studies) may show that CTP abnormalities are more prevalent than previously noted. It is also unclear if these changes are associated with TIA severity. To demonstrate that TIA patients are associated with perfusion deficits using whole brain 320-detector-row CT perfusion, and to determine an association between ABCD2 score and perfusion deficit using whole brain perfusion. We retrospectively reviewed all TIA patients for CTP deficits from 2008-2010. Perfusion imaging was reviewed at admission; and it was determined if a perfusion deficit was present along with vascular territory involved. Of 364 TIA patients, 62 patients had CTP deficits. The largest group of patients had MCA territory involved with 48 of 62 patients (77.42%). The most common perfusion abnormality was increased TTP with 46 patients (74.19%). The ABCD2 score was reviewed in association with perfusion deficit. Increased age >60, severe hypertension (>180/100 mmHg), patients with speech abnormalities, and duration of symptoms >10 min were associated with a perfusion deficit but history of diabetes or minimal/moderate hypertension (140/90-179/99 mmHg) was not. There was no association between motor deficit and perfusion abnormality. Perfusion deficits are found in TIA patients using whole brain CTP and associated with components of the ABCD2 score.

  5. Normal values of regional left ventricular myocardial thickness, mass and distribution-assessed by 320-detector computed tomography angiography in the Copenhagen General Population Study.

    PubMed

    Hindsø, Louise; Fuchs, Andreas; Kühl, Jørgen Tobias; Nilsson, Emma Julia P; Sigvardsen, Per Ejlstrup; Køber, Lars; Nordestgaard, Børge G; Kofoed, Klaus Fuglsang

    2017-03-01

    Left ventricular (LV) hypertrophy is associated with cardiovascular complications and the geometry is important for prognosis. In some cardiovascular diseases, myocardial hypertrophy or dilation occurs regionally without modifying the global size of the heart. It is therefore relevant to determine regional normal reference values of the left ventricle. The aim of this study was to derive reference values of regional LV myocardial thickness (LVMT) and mass (LVMM) from a healthy study group of the general population using cardiac computed tomography angiography (CCTA). We wanted to introduce LV myocardial distribution (LVMD) as a measure of regional variation of the LVMT. Moreover, we wanted to determine whether these parameters varied between men and women. We studied 568 (181 men; 32%) adults, free of cardiovascular disease and risk factors, who underwent 320-detector CCTA. Mean age was 55 (range 40-84) years. Regional LVMT and LVMM were measured, according to the American Heart Association's 17 segment model, using semi-automatic software. Mean LVMT were 6.6 mm for men and 5.4 mm for women (p < 0.001). The normal LV was thickest in the basal septum (segment 3; men = 8.3 mm; women = 7.2 mm) and thinnest in the mid-ventricular anterior wall (segment 7; men = 5.6 mm; women = 4.5 mm) for both men and women. However, the regional LVMD differed between men and women, with the LV being most heterogenic in women. The normal human LV is morphologically heterogenic, and showed same overall pattern but different regional distribution for men and women. This study introduces LVMD and provides gender specific reference values for regional LVMT, LVMM, and LVMD.

  6. Quantification of coronary flow using dynamic angiography with 320-detector row CT and motion coherence image processing: Detection of ischemia for intermediate coronary stenosis.

    PubMed

    Nagao, Michinobu; Yamasaki, Yuzo; Kamitani, Takeshi; Kawanami, Satoshi; Sagiyama, Koji; Yamanouchi, Torahiko; Shimomiya, Yamato; Matoba, Tetsuya; Mukai, Yasushi; Odashiro, Keita; Baba, Shingo; Maruoka, Yasuhiro; Kitamura, Yoshiyuki; Nishie, Akihiro; Honda, Hiroshi

    2016-05-01

    Anatomical coronary stenosis is not always indicative of functional stenosis, particularly for intermediate coronary lesions. The purpose of this study is to propose a new method for quantifying coronary flow using dynamic CT angiography for the whole heart (heart-DCT) and investigate its ability for detecting ischemia from intermediate coronary stenosis. Participants comprised 36 patients with coronary artery disease who underwent heart-DCT using 320-detector CT with tube voltage of 80kV and myocardial perfusion scintigraphy (MPS). Heart-DCT was continuously performed at mid-diastole throughout 15-25 cardiac cycles with prospective ECG-gating after bolus injection of contrast media (12-24ml). Dynamic datasets were computed into 90-100 data sets by motion coherence image processing (MCIP). Next, time-density curves (TDCs) for coronary arteries with a diameter >3mm were automatically calculated for all phases using MCIP. On the basis of the maximum slope method, coronary flow index (CFI) was defined as the ratio of the maximum upslope of coronary artery attenuation to the upslope of ascending aorta attenuation on the TDC, and was used to quantify coronary flow. CFIs for the proximal and distal sites of coronary arteries with mild-to-moderate stenosis were calculated. Coronary territories were categorized as non-ischemic or ischemic by MPS. Receiver-operating-characteristic (ROC) analysis was performed to determine the optimal cutoff for CFI to detect ischemia. Distal CFI was significantly lower for ischemia (0.26±0.08) than for non-ischemia (0.50±0.17, p<0.0001). No significant difference in proximal CFI was seen between ischemia (0.55±0.23) and non-ischemia (0.62±0.24). ROC analysis revealed 0.39 as the optimal cutoff for distal CFI to detect ischemia, with C-statistics of 0.91, 100% sensitivity, and 75% specificity. This novel imaging technique allows coronary flow quantification using heart-DCT. Distal CFI can detect myocardial ischemia derived from

  7. Prospective evaluation of the influence of iterative reconstruction on the reproducibility of coronary calcium quantification in reduced radiation dose 320 detector row CT.

    PubMed

    Choi, Andrew D; Leifer, Eric S; Yu, Jeannie; Shanbhag, Sujata M; Bronson, Kathie; Arai, Andrew E; Chen, Marcus Y

    2016-01-01

    Coronary artery calcium (CAC) predicts coronary heart disease events and is important for individualized cardiac risk assessment. This report assesses the interscan variability of CT for coronary calcium quantification using image acquisition with standard and reduced radiation dose protocols and whether the use of reduced radiation dose acquisition with iterative reconstruction (IR; "reduced-dose/IR ") allows for similar image quality and reproducibility when compared to standard radiation dose acquisition with filtered back projection (FBP; "standard-dose/FBP") on 320-detector row computed tomography (320-CT). 200 consecutive patients (60 ± 9 years, 59% male) prospectively underwent two standard- and two reduced-dose acquisitions (800 total scans, 1600 reconstructions) using 320 slice CT and 120 kV tube voltage. Automated tube current modulation was used and for reduced-dose scans, prescribed tube current was lowered by 70%. Image noise and Agatston scores were determined and compared. Regarding stratification by Agatston score categories (0, 1-10, 11-100, 101-400, >400), reduced-dose/IR versus standard-dose/FBP had excellent agreement at 89% (95% CI: 86-92%) with kappa 0.86 (95% CI: 0.81-0.90). Standard-dose/FBP rescan agreement was 93% (95% CI: 89-96%) with kappa = 0.91 (95% CI: 0.86-0.95) while reduced-dose/IR rescan agreement was similar at 91% (95% CI: 87-94%) with kappa 0.88 (95% CI: 0.83-0.93). Image noise was significantly higher but clinically acceptable for reduced-dose/IR (18 Hounsfield Unit [HU] mean) compared to standard-dose/FBP (16 HU; p < 0.0001). Median radiation exposure was 74% lower for reduced- (0.37 mSv) versus standard-dose (1.4 mSv) acquisitions. Rescan agreement was excellent for reduced-dose image acquisition with iterative reconstruction and standard-dose acquisition with filtered back projection for the quantification of coronary calcium by CT. These methods make it possible to reduce radiation exposure by 74%. URL: https

  8. Coronary CT angiography using the second-generation 320-detector row CT: assessment of image quality and radiation dose in various heart rates compared with the first-generation scanner.

    PubMed

    Tomizawa, Nobuo; Maeda, Eriko; Akahane, Masaaki; Torigoe, Rumiko; Kiryu, Shigeru; Ohtomo, Kuni

    2013-10-01

    To assess the image quality and radiation dose reduction in various heart rates in coronary CT angiography using the second-generation 320-detector row CT compared with the first-generation CT. Ninety-six patients were retrospectively included. The first 48 patients underwent coronary CT angiography with the first-generation 320-detector row CT, while the last 48 patients underwent with the second-generation CT. Subjective image quality was graded using a 4-point scale (4, excellent; 1, unable to evaluate). Image noise and contrast-to-noise ratio were also analyzed. Subgroup analysis was performed based on the heart rate. The mean effective dose was derived from the dose length product multiplied by a conversion coefficient for the chest (κ = 0.014 mSv × mGy(-1) × cm(-1)). The overall subjective image quality score showed no significant difference (3.66 vs 3.69, respectively, p = 0.25). The image quality score of the second-generation group tended to be higher than that of the first-generation group in the 66- to 75-bpm subgroup (3.36 vs 3.53, respectively, p = 0.07). No significant difference was observed in image noise and contrast-to-noise ratio. The overall radiation dose reduced by 24 % (3.3 vs 2.5 mSv, respectively, p = 0.03), and the reduction was substantial in patients with higher heart rate (66- to 75-bpm, 4.3 vs 2.2 mSv, respectively, p = 0.009; >75 bpm, 8.2 vs 3.7 mSv, respectively, p = 0.005). The second-generation 320-detector row CT could maintain the image quality while reducing the radiation dose in coronary CT angiography. The dose reduction was larger in patients with higher heart rate.

  9. Volumetric magnetic induction tomography

    NASA Astrophysics Data System (ADS)

    Wei, H.-Y.; Ma, L.; Soleimani, M.

    2012-05-01

    Magnetic induction tomography (MIT) is a new and emerging type of tomography technique that is able to map the passive electromagnetic properties (in particular conductivity) of an object. Because of its non-invasive feature, it becomes a suitable technique for many industries, such as metal processing and mining. This paper presents a volumetric MIT (VMIT) system based on an existing measurement setup in our 2D system (MIT Mk-I). By increasing the number of sensors in the axial direction, volumetric imaging can be realized and hence can improve the spatial resolution of the reconstructed images. All of the system control, data acquisition and signal demodulation are accomplished by a commercial data acquisition card and the National Instruments graphical programming language. In this paper, both the system architecture and the forward 3D sensitivity model will be presented. The image reconstruction scheme is modified by introducing a 3D sensitivity map to replace the previous 2D sensitivity map used for the MIT Mk-I system. The iterative Landweber technique was implemented as the inverse solver to reconstruct the images. Several laboratory-based experimental results are demonstrated in this paper, with different shapes of imaging objects. The reconstructed images are satisfactory showing for the first time volumetric conductivity reconstruction using a multi-layer MIT system. The results indicate the high-quality image reconstruction using our novel VMIT system for potential use in industrial applications, such as metal flow imaging.

  10. Volumetric Combustion Diagnostics

    DTIC Science & Technology

    2017-01-03

    VLIF), 4) the investigation and validation of Volumetric Particle Image Velocimetry (VPIV), 5) the use of fiber bundles in volumetric tomography, and 6...Volumetric Laser Induced Fluorescence (VLIF)………………………………………… 6 2.4. Volumetric Particle Image Velocimetry (VPIV)………………………………………… 9 2.5. Use of Fiber...underway. 4. Volumetric Particle Image Velocimetry (VPIV) This objective was partially completed and will continue into the second year. We have

  11. Axial spondyloarthritis.

    PubMed

    Sieper, Joachim; Braun, Jürgen; Dougados, Maxime; Baeten, Dominique

    2015-07-09

    The term axial spondyloarthritis covers both non-radiographic disease and radiographic disease (also known as ankylosing spondylitis). Some studies have been performed to investigate the prevalence of axial spondyloarthritis, although most are limited to patients with radiographic disease. A strong genetic association has been shown between axial spondyloarthritis and human leukocyte antigen-B27 (HLA-B27), but the pathogenetic role of HLA-B27 has not yet been clarified. Tumour necrosis factor (TNF), IL-17, IL-23 and downstream pathways also seem to be important - based on the good results of therapies directed against these molecules - but their exact role in the inflammatory process is also not yet clear. Elucidating the interaction between osteoproliferation and inflammation will be crucial for the prevention of long-term structural damage of the bone. The development of new criteria for classification, diagnosis and screening of patients with axial spondyloarthritis will enable earlier intervention for this chronic inflammatory disease. MRI has become an important tool for the early detection of axial spondyloarthritis. NSAIDs and TNF blockers are effective therapies, including in the early non-radiographic stage. Therapeutic blockade of IL-17 or IL-23 seems to be a promising new treatment option. Tools for measuring quality of life in axial spondyloarthritis have become relevant to assess the impact that the disease has on patients. These diagnostic and therapeutic advances will continue to change the management of axial spondyloarthritis, and new insights into the disease pathogenesis will hopefully accelerate this process. For an illustrated summary of this Primer, visit: http://go.nature.com/51b1af.

  12. Axial Pump

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George Arthur (Inventor); Bacak, James W. (Inventor); Svejkovsky, Paul A. (Inventor); Benkowski, Robert J. (Inventor)

    1997-01-01

    A rotary blood pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial and radial clearances of blades associated with the flow straightener, inducer portion, impeller portion and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with cross-linked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

  13. Axial superchargers

    NASA Technical Reports Server (NTRS)

    Betz, A

    1944-01-01

    Improvements, however, have been attained which permit a shortening of the structure without any impairment of the efficiency. The axial supercharger has a better efficiency and a simpler design than the radial supercharger. The relatively narrow range in which it operates satisfactorily should not be a very disturbing factor for practical flight problems. The length of this type of supercharger may be reduced considerably if some impairment in the efficiency is permitted.

  14. PSF engineering in multifocus microscopy for increased depth volumetric imaging

    PubMed Central

    Hajj, Bassam; El Beheiry, Mohamed; Dahan, Maxime

    2016-01-01

    Imaging and localizing single molecules with high accuracy in a 3D volume is a challenging task. Here we combine multifocal microscopy, a recently developed volumetric imaging technique, with point spread function engineering to achieve an increased depth for single molecule imaging. Applications in 3D single molecule localization-based super-resolution imaging is shown over an axial depth of 4 µm as well as for the tracking of diffusing beads in a fluid environment over 8 µm. PMID:27231584

  15. Flexible Volumetric Structure

    NASA Technical Reports Server (NTRS)

    Cagle, Christopher M. (Inventor); Schlecht, Robin W. (Inventor)

    2014-01-01

    A flexible volumetric structure has a first spring that defines a three-dimensional volume and includes a serpentine structure elongatable and compressible along a length thereof. A second spring is coupled to at least one outboard edge region of the first spring. The second spring is a sheet-like structure capable of elongation along an in-plane dimension thereof. The second spring is oriented such that its in-plane dimension is aligned with the length of the first spring's serpentine structure.

  16. Continuous volumetric imaging via an optical phase-locked ultrasound lens

    PubMed Central

    Kong, Lingjie; Tang, Jianyong; Little, Justin P.; Yu, Yang; Lämmermann, Tim; Lin, Charles P.; Germain, Ronald N.; Cui, Meng

    2015-01-01

    In vivo imaging at high spatiotemporal resolution holds the key to the fundamental understanding of complex biological systems. Integrating an optical phase-locked ultrasound lens into a conventional two-photon fluorescence microscope, we achieved microsecond scale axial scanning, which enabled high-speed volumetric imaging. We applied this system to multicolor volumetric imaging of fast processes, including calcium dynamics in the cerebral cortex of behaving mice, and transient morphology changes and trafficking of immune cells. PMID:26167641

  17. Snapshot Hyperspectral Volumetric Microscopy

    PubMed Central

    Wu, Jiamin; Xiong, Bo; Lin, Xing; He, Jijun; Suo, Jinli; Dai, Qionghai

    2016-01-01

    The comprehensive analysis of biological specimens brings about the demand for capturing the spatial, temporal and spectral dimensions of visual information together. However, such high-dimensional video acquisition faces major challenges in developing large data throughput and effective multiplexing techniques. Here, we report the snapshot hyperspectral volumetric microscopy that computationally reconstructs hyperspectral profiles for high-resolution volumes of ~1000 μm × 1000 μm × 500 μm at video rate by a novel four-dimensional (4D) deconvolution algorithm. We validated the proposed approach with both numerical simulations for quantitative evaluation and various real experimental results on the prototype system. Different applications such as biological component analysis in bright field and spectral unmixing of multiple fluorescence are demonstrated. The experiments on moving fluorescent beads and GFP labelled drosophila larvae indicate the great potential of our method for observing multiple fluorescent markers in dynamic specimens. PMID:27103155

  18. Snapshot Hyperspectral Volumetric Microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Jiamin; Xiong, Bo; Lin, Xing; He, Jijun; Suo, Jinli; Dai, Qionghai

    2016-04-01

    The comprehensive analysis of biological specimens brings about the demand for capturing the spatial, temporal and spectral dimensions of visual information together. However, such high-dimensional video acquisition faces major challenges in developing large data throughput and effective multiplexing techniques. Here, we report the snapshot hyperspectral volumetric microscopy that computationally reconstructs hyperspectral profiles for high-resolution volumes of ~1000 μm × 1000 μm × 500 μm at video rate by a novel four-dimensional (4D) deconvolution algorithm. We validated the proposed approach with both numerical simulations for quantitative evaluation and various real experimental results on the prototype system. Different applications such as biological component analysis in bright field and spectral unmixing of multiple fluorescence are demonstrated. The experiments on moving fluorescent beads and GFP labelled drosophila larvae indicate the great potential of our method for observing multiple fluorescent markers in dynamic specimens.

  19. VOLUMETRIC TANK TESTING: AN OVERVIEW

    EPA Science Inventory

    This report summarizes the technical findings of an EPA study on volumetric tank testing. It describes the results of the EPA study, which evaluated the viability of volumetric tank tests as a means of detecting leaks in underground storage tanks. It explains the accuracy requi...

  20. VOLUMETRIC TANK TESTING: AN OVERVIEW

    EPA Science Inventory

    This report summarizes the technical findings of an EPA study on volumetric tank testing. The results of this study, which evaluated the viability of volumetric tank tests as a means of detecting leaks in underground storage tanks, are described. Also, the accuracy requirements s...

  1. Light axial vector mesons

    NASA Astrophysics Data System (ADS)

    Chen, Kan; Pang, Cheng-Qun; Liu, Xiang; Matsuki, Takayuki

    2015-04-01

    Inspired by the abundant experimental observation of axial-vector states, we study whether the observed axial-vector states can be categorized into the conventional axial-vector meson family. In this paper we carry out an analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial-vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial-vector mesons, which are valuable for further experimental exploration of the observed and predicted axial-vector mesons.

  2. Synoptic volumetric variations and flushing of the Tampa Bay estuary

    NASA Astrophysics Data System (ADS)

    Wilson, M.; Meyers, S. D.; Luther, M. E.

    2014-03-01

    Two types of analyses are used to investigate the synoptic wind-driven flushing of Tampa Bay in response to the El Niño-Southern Oscillation (ENSO) cycle from 1950 to 2007. Hourly sea level elevations from the St. Petersburg tide gauge, and wind speed and direction from three different sites around Tampa Bay are used for the study. The zonal (u) and meridional (v) wind components are rotated clockwise by 40° to obtain axial and co-axial components according to the layout of the bay. First, we use the subtidal observed water level as a proxy for mean tidal height to estimate the rate of volumetric bay outflow. Second, we use wavelet analysis to bandpass sea level and wind data in the time-frequency domain to isolate the synoptic sea level and surface wind variance. For both analyses the long-term monthly climatology is removed and we focus on the volumetric and wavelet variance anomalies. The overall correlation between the Oceanic Niño Index and volumetric analysis is small due to the seasonal dependence of the ENSO response. The mean monthly climatology between the synoptic wavelet variance of elevation and axial winds are in close agreement. During the winter, El Niño (La Niña) increases (decreases) the synoptic variability, but decreases (increases) it during the summer. The difference in winter El Niño/La Niña wavelet variances is about 20 % of the climatological value, meaning that ENSO can swing the synoptic flushing of the bay by 0.22 bay volumes per month. These changes in circulation associated with synoptic variability have the potential to impact mixing and transport within the bay.

  3. Quantitative Techniques in Volumetric Analysis

    NASA Astrophysics Data System (ADS)

    Zimmerman, John; Jacobsen, Jerrold J.

    1996-12-01

    Quantitative Techniques in Volumetric Analysis is a visual library of techniques used in making volumetric measurements. This 40-minute VHS videotape is designed as a resource for introducing students to proper volumetric methods and procedures. The entire tape, or relevant segments of the tape, can also be used to review procedures used in subsequent experiments that rely on the traditional art of quantitative analysis laboratory practice. The techniques included are: Quantitative transfer of a solid with a weighing spoon Quantitative transfer of a solid with a finger held weighing bottle Quantitative transfer of a solid with a paper strap held bottle Quantitative transfer of a solid with a spatula Examples of common quantitative weighing errors Quantitative transfer of a solid from dish to beaker to volumetric flask Quantitative transfer of a solid from dish to volumetric flask Volumetric transfer pipet A complete acid-base titration Hand technique variations The conventional view of contemporary quantitative chemical measurement tends to focus on instrumental systems, computers, and robotics. In this view, the analyst is relegated to placing standards and samples on a tray. A robotic arm delivers a sample to the analysis center, while a computer controls the analysis conditions and records the results. In spite of this, it is rare to find an analysis process that does not rely on some aspect of more traditional quantitative analysis techniques, such as careful dilution to the mark of a volumetric flask. Figure 2. Transfer of a solid with a spatula. Clearly, errors in a classical step will affect the quality of the final analysis. Because of this, it is still important for students to master the key elements of the traditional art of quantitative chemical analysis laboratory practice. Some aspects of chemical analysis, like careful rinsing to insure quantitative transfer, are often an automated part of an instrumental process that must be understood by the

  4. A comparative study between axial and radial fluxfocusing magnetic gear topologies and mechanical gearboxes

    NASA Astrophysics Data System (ADS)

    Calvin, Matthew

    A variety of magnetic gear topologies have been investigated in recent years as alternatives to traditional mechanical gearboxes. In general these magnetic gears offer advantages in the non-contact transmission of torque including inherent overload protection, reduced acoustic emissions, and a reduction in the number of contacting components subject to wear. The earliest magnetic gear designs however suffered from low volumetric torque densities, which limited their utility for industrial applications. Research into flux focusing magnetic gearbox topologies has resulted in increased volumetric torque densities by actively engaging all of the magnets in the transmission of torque throughout the process. This research compared the volumetric torque density of axial and radial flux focusing magnetic gearbox designs and prototypes to planetary, cycloidal, and harmonic mechanical gearboxes. The rare earth scaled up radial and axial flux focusing topologies were found to have consistently higher volumetric torque densities than planetary gearboxes of comparable diameter. The cycloidal and harmonic gearboxes had comparable volumetric torque densities, with greater volumetric torque densities for some models and lesser volumetric torque densities for others. The expectation is that further improvements in volumetric torque density are possible for flux focusing magnetic gears with additional refinement and optimization of the designs. The current study does show that flux focusing magnetic gear topologies are a plausible future alternative to mechanical gearboxes in applications where their unique torque transmission mechanism would be advantageous.

  5. Volumetric Light-Field Excitation

    PubMed Central

    Schedl, David C.; Bimber, Oliver

    2016-01-01

    We explain how to concentrate light simultaneously at multiple selected volumetric positions by means of a 4D illumination light field. First, to select target objects, a 4D imaging light field is captured. A light field mask is then computed automatically for this selection to avoid illumination of the remaining areas. With one-photon illumination, simultaneous generation of complex volumetric light patterns becomes possible. As a full light-field can be captured and projected simultaneously at the desired exposure and excitation times, short readout and lighting durations are supported. PMID:27363565

  6. Rapid mapping of volumetric errors

    SciTech Connect

    Krulewich, D.; Hale, L.; Yordy, D.

    1995-09-13

    This paper describes a relatively inexpensive, fast, and easy to execute approach to mapping the volumetric errors of a machine tool, coordinate measuring machine, or robot. An error map is used to characterize a machine or to improve its accuracy by compensating for the systematic errors. The method consists of three steps: (1) modeling the relationship between the volumetric error and the current state of the machine; (2) acquiring error data based on length measurements throughout the work volume; and (3) optimizing the model to the particular machine.

  7. BWR AXIAL PROFILE

    SciTech Connect

    J. Huffer

    2004-09-28

    The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I.

  8. Measuring axial pump thrust

    DOEpatents

    Suchoza, Bernard P.; Becse, Imre

    1988-01-01

    An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices.

  9. Measuring axial pump thrust

    DOEpatents

    Suchoza, B.P.; Becse, I.

    1988-11-08

    An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices. 1 fig.

  10. Computerised Axial Tomography (CAT)

    DTIC Science & Technology

    1990-06-01

    Ministry of’ Defence, Defence Research Information Centre, UK. Computerised Axial Tomography ( CAT ) Report Secufty C"uMiauion tide Onadtiicadon (U. R, Cor S...DRIC T 8485 COMPUTERISED AXIAL TOMOGRAPHY ( CAT ) F.P. GENTILE, F. SABETTA, V. TRO1* ISS R 78/4.Rome, 1.5 Mlarch 1978 (from Italian) B Distribution(f...dello Radiazioni ISSN 0390--6477 F.P. GENTILE, F. SABETTA. V. TROI Computerised Axial Tomography ( CAT ) March 15, 1978). This paper is a review of

  11. [Management of axial spondyloarthritis].

    PubMed

    Kiltz, U; Baraliakos, X; Braun, J

    2016-11-01

    The term spondyloarthritis (SpA) is now increasingly used to classify and diagnose patients who are characterized by inflammation in the axial skeleton and peripheral manifestations (arthritis and enthesitis). The management of SpA should be tailored according to the current manifestations of the disease, the disease activity and functional impairment. The current article focuses on diagnosis and therapy in patients with axial SpA. Diagnostic procedures are discussed in light of diagnostic utility and feasibility in daily routine care. Cornerstones of treatment in patients with axial SpA are a combination of regular exercise and pharmacological treatment options aiming at anti-inflammatory strategies.

  12. Slow Growing Volumetric Subdivision for 3D Volumetric Data

    SciTech Connect

    Pascucci, V; Kahn, S; Kelley, R; Kilbourne, C; Porter, F; Wargelin, B

    2004-12-16

    In recent years subdivision methods have been successfully applied to the multi-resolution representation and compression of surface meshes. Unfortunately their use in the volumetric case has remained impractical because of the use of tensor-product generalizations that induce an excessive growth of the mesh size before sufficient number is preformed. This technical sketch presents a new subdivision technique that refines volumetric (and higher-dimensional) meshes at the same rate of surface meshes. The scheme builds adaptive refinements of a mesh without using special decompositions of the cells connecting different levels of resolution. Lower dimensional ''sharp'' features are also handled directly in a natural way. The averaging rules allow to reproduce the same smoothness of the two best known previous tensor product refinement methods.

  13. Axial static mixer

    DOEpatents

    Sandrock, H.E.

    1982-05-06

    Static axial mixing apparatus includes a plurality of channels, forming flow paths of different dimensions. The axial mixer includes a flow adjusting device for adjustable selective control of flow resistance of various flow paths in order to provide substantially identical flows through the various channels, thereby reducing nonuniform coating of interior surfaces of the channels. The flow adjusting device may include diaphragm valves, and may further include a pressure regulating system therefor.

  14. Axial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  15. Volumetric imaging of fish locomotion

    PubMed Central

    Flammang, Brooke E.; Lauder, George V.; Troolin, Daniel R.; Strand, Tyson E.

    2011-01-01

    Fishes use multiple flexible fins in order to move and maintain stability in a complex fluid environment. We used a new approach, a volumetric velocimetry imaging system, to provide the first instantaneous three-dimensional views of wake structures as they are produced by freely swimming fishes. This new technology allowed us to demonstrate conclusively the linked ring vortex wake pattern that is produced by the symmetrical (homocercal) tail of fishes, and to visualize for the first time the three-dimensional vortex wake interaction between the dorsal and anal fins and the tail. We found that the dorsal and anal fin wakes were rapidly (within one tail beat) assimilated into the caudal fin vortex wake. These results show that volumetric imaging of biologically generated flow patterns can reveal new features of locomotor dynamics, and provides an avenue for future investigations of the diversity of fish swimming patterns and their hydrodynamic consequences. PMID:21508026

  16. Volumetric imaging of fish locomotion.

    PubMed

    Flammang, Brooke E; Lauder, George V; Troolin, Daniel R; Strand, Tyson E

    2011-10-23

    Fishes use multiple flexible fins in order to move and maintain stability in a complex fluid environment. We used a new approach, a volumetric velocimetry imaging system, to provide the first instantaneous three-dimensional views of wake structures as they are produced by freely swimming fishes. This new technology allowed us to demonstrate conclusively the linked ring vortex wake pattern that is produced by the symmetrical (homocercal) tail of fishes, and to visualize for the first time the three-dimensional vortex wake interaction between the dorsal and anal fins and the tail. We found that the dorsal and anal fin wakes were rapidly (within one tail beat) assimilated into the caudal fin vortex wake. These results show that volumetric imaging of biologically generated flow patterns can reveal new features of locomotor dynamics, and provides an avenue for future investigations of the diversity of fish swimming patterns and their hydrodynamic consequences.

  17. Volumetric direct nuclear pumped laser

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.; Hohl, F.; Deyoung, R. J.; Williams, M. D. (Inventor)

    1978-01-01

    A volumetric direct nuclear pumped laser was developed in which the gas is a mixture of He-3 and a minority gas from the group of argon, krypton, xenon, chlorine and fluorine. The mixture of He-3 and the minority gas produces lasing with a minority gas concentration of from 0.01 to 10 percent argon, 1 percent krypton, 0.01 to 5 percent xenon and small concentrations of chlorine or fluorine.

  18. Fast volumetric imaging with patterned illumination via digital micro-mirror device-based temporal focusing multiphoton microscopy.

    PubMed

    Chang, Chia-Yuan; Hu, Yvonne Yuling; Lin, Chun-Yu; Lin, Cheng-Han; Chang, Hsin-Yu; Tsai, Sheng-Feng; Lin, Tzu-Wei; Chen, Shean-Jen

    2016-05-01

    Temporal focusing multiphoton microscopy (TFMPM) has the advantage of area excitation in an axial confinement of only a few microns; hence, it can offer fast three-dimensional (3D) multiphoton imaging. Herein, fast volumetric imaging via a developed digital micromirror device (DMD)-based TFMPM has been realized through the synchronization of an electron multiplying charge-coupled device (EMCCD) with a dynamic piezoelectric stage for axial scanning. The volumetric imaging rate can achieve 30 volumes per second according to the EMCCD frame rate of more than 400 frames per second, which allows for the 3D Brownian motion of one-micron fluorescent beads to be spatially observed. Furthermore, it is demonstrated that the dynamic HiLo structural multiphoton microscope can reject background noise by way of the fast volumetric imaging with high-speed DMD patterned illumination.

  19. Fast volumetric imaging with patterned illumination via digital micro-mirror device-based temporal focusing multiphoton microscopy

    PubMed Central

    Chang, Chia-Yuan; Hu, Yvonne Yuling; Lin, Chun-Yu; Lin, Cheng-Han; Chang, Hsin-Yu; Tsai, Sheng-Feng; Lin, Tzu-Wei; Chen, Shean-Jen

    2016-01-01

    Temporal focusing multiphoton microscopy (TFMPM) has the advantage of area excitation in an axial confinement of only a few microns; hence, it can offer fast three-dimensional (3D) multiphoton imaging. Herein, fast volumetric imaging via a developed digital micromirror device (DMD)-based TFMPM has been realized through the synchronization of an electron multiplying charge-coupled device (EMCCD) with a dynamic piezoelectric stage for axial scanning. The volumetric imaging rate can achieve 30 volumes per second according to the EMCCD frame rate of more than 400 frames per second, which allows for the 3D Brownian motion of one-micron fluorescent beads to be spatially observed. Furthermore, it is demonstrated that the dynamic HiLo structural multiphoton microscope can reject background noise by way of the fast volumetric imaging with high-speed DMD patterned illumination. PMID:27231617

  20. Volumetric Three-Dimensional Display Systems

    NASA Astrophysics Data System (ADS)

    Blundell, Barry G.; Schwarz, Adam J.

    2000-03-01

    A comprehensive study of approaches to three-dimensional visualization by volumetric display systems This groundbreaking volume provides an unbiased and in-depth discussion on a broad range of volumetric three-dimensional display systems. It examines the history, development, design, and future of these displays, and considers their potential for application to key areas in which visualization plays a major role. Drawing substantially on material that was previously unpublished or available only in patent form, the authors establish the first comprehensive technical and mathematical formalization of the field, and examine a number of different volumetric architectures. System level design strategies are presented, from which proposals for the next generation of high-definition predictable volumetric systems are developed. To ensure that researchers will benefit from work already completed, they provide: * Descriptions of several recent volumetric display systems prepared from material supplied by the teams that created them * An abstract volumetric display system design paradigm * An historical summary of 90 years of development in volumetric display system technology * An assessment of the strengths and weaknesses of many of the systems proposed to date * A unified presentation of the underlying principles of volumetric display systems * A comprehensive bibliography Beautifully supplemented with 17 color plates that illustrate volumetric images and prototype displays, Volumetric Three-Dimensional Display Systems is an indispensable resource for professionals in imaging systems development, scientific visualization, medical imaging, computer graphics, aerospace, military planning, and CAD/CAE.

  1. Volumetric imaging of fast biological dynamics in deep tissue via wavefront engineering

    NASA Astrophysics Data System (ADS)

    Kong, Lingjie; Tang, Jianyong; Cui, Meng

    2016-03-01

    To reveal fast biological dynamics in deep tissue, we combine two wavefront engineering methods that were developed in our laboratory, namely optical phase-locked ultrasound lens (OPLUL) based volumetric imaging and iterative multiphoton adaptive compensation technique (IMPACT). OPLUL is used to generate oscillating defocusing wavefront for fast axial scanning, and IMPACT is used to compensate the wavefront distortions for deep tissue imaging. We show its promising applications in neuroscience and immunology.

  2. Volumetric structured illumination microscopy enabled by tunable focus lens (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hinsdale, Taylor; Malik, Bilal; Olsovsky, Cory; Jo, Javier A.; Maitland, Kristen C.

    2016-03-01

    We present a volumetric imaging method for biological tissue that is free of mechanically scanning components. The optical sectioning in the system is obtained by structured illumination microscopy (SIM) with the depth of focus being varied by the use of an electronic tunable-focus lens (ETL). The performance of the axial scanning mechanism was evaluated and characterized in conjunction with SIM to ensure volumetric images could be recorded and reconstructed without significant losses in optical section thickness and lateral resolution over the full desired scan range. It was demonstrated that sub-cellular image resolutions were obtainable in both microsphere films and in ex vivo oral mucosa, spanning multiple cell layers, without significant losses in image quality. The mechanism proposed here has the ability to be integrated into any wide-field microscopy system to convert it into a three-dimensional imaging platform without the need for axial scanning of the sample or imaging optics. The ability to axially scan independent of mechanical movement also provides the opportunity for the development of endoscopic systems which can create volumetric images of tissue in vivo.

  3. Altered Axial Skeletal Development

    EPA Science Inventory

    The axial skeleton is routinely examined in standard developmental toxicity bioassays and has proven to be sensitive to a wide variety of chemical agents. Dysmorphogenesis in the skull, vertebral column and ribs has been described in both human populations and in laboratory anima...

  4. Altered Axial Skeletal Development

    EPA Science Inventory

    The axial skeleton is routinely examined in standard developmental toxicity bioassays and has proven to be sensitive to a wide variety of chemical agents. Dysmorphogenesis in the skull, vertebral column and ribs has been described in both human populations and in laboratory anima...

  5. Volumetric Acoustic Vector Intensity Probe

    NASA Technical Reports Server (NTRS)

    Klos, Jacob

    2006-01-01

    A new measurement tool capable of imaging the acoustic intensity vector throughout a large volume is discussed. This tool consists of an array of fifty microphones that form a spherical surface of radius 0.2m. A simultaneous measurement of the pressure field across all the microphones provides time-domain near-field holograms. Near-field acoustical holography is used to convert the measured pressure into a volumetric vector intensity field as a function of frequency on a grid of points ranging from the center of the spherical surface to a radius of 0.4m. The volumetric intensity is displayed on three-dimensional plots that are used to locate noise sources outside the volume. There is no restriction on the type of noise source that can be studied. The sphere is mobile and can be moved from location to location to hunt for unidentified noise sources. An experiment inside a Boeing 757 aircraft in flight successfully tested the ability of the array to locate low-noise-excited sources on the fuselage. Reference transducers located on suspected noise source locations can also be used to increase the ability of this device to separate and identify multiple noise sources at a given frequency by using the theory of partial field decomposition. The frequency range of operation is 0 to 1400Hz. This device is ideal for the study of noise sources in commercial and military transportation vehicles in air, on land and underwater.

  6. Volumetric-driven flows on the Plasma Couette Experiment

    NASA Astrophysics Data System (ADS)

    Flanagan, Ken; Clark, M. M.; Lynn, J.; Siller, R.; Tabbutt, M.; Wallace, J.; Xu, Y.; Forest, C. B.

    2016-10-01

    Experiments for driving Keplerian-like flow profiles with the goal of exciting the magnetorotational instability (MRI) on the Plasma Couette Experiment Upgrade (PCX-U) are described. Instead of driving flow at the boundaries as is typical in many liquid metal Couette experiments, a global drive is implemented. A large (20+ A) radial current is drawn across a small (1-3 G) axial field generating torque across the whole profile. This volumetric-driven flow (VDF) is capable of producing profiles similar to Keplerian flow with Alfvén Mach numbers of order unity-ideal for MRI studies. Experimental measurements will be compared to numerical calculations that show that at sufficiently high magnetic and fluid Reynolds numbers, VDF can drive the MRI. This work is supported by the NSF.

  7. Volumetric optical coherence microscopy enabled by aberrated optics (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Mulligan, Jeffrey A.; Liu, Siyang; Adie, Steven G.

    2017-02-01

    Optical coherence microscopy (OCM) is an interferometric imaging technique that enables high resolution, non-invasive imaging of 3D cell cultures and biological tissues. Volumetric imaging with OCM suffers a trade-off between high transverse resolution and poor depth-of-field resulting from defocus, optical aberrations, and reduced signal collection away from the focal plane. While defocus and aberrations can be compensated with computational methods such as interferometric synthetic aperture microscopy (ISAM) or computational adaptive optics (CAO), reduced signal collection must be physically addressed through optical hardware. Axial scanning of the focus is one approach, but comes at the cost of longer acquisition times, larger datasets, and greater image reconstruction times. Given the capabilities of CAO to compensate for general phase aberrations, we present an alternative method to address the signal collection problem without axial scanning by using intentionally aberrated optical hardware. We demonstrate the use of an astigmatic spectral domain (SD-)OCM imaging system to enable single-acquisition volumetric OCM in 3D cell culture over an extended depth range, compared to a non-aberrated SD-OCM system. The transverse resolution of the non-aberrated and astigmatic imaging systems after application of CAO were 2 um and 2.2 um, respectively. The depth-range of effective signal collection about the nominal focal plane was increased from 100 um in the non-aberrated system to over 300 um in the astigmatic system, extending the range over which useful data may be acquired in a single OCM dataset. We anticipate that this method will enable high-throughput cellular-resolution imaging of dynamic biological systems over extended volumes.

  8. Volumetric apparel for visible female

    NASA Astrophysics Data System (ADS)

    Wu, Zhongke; Goh, Shuang R.; Kluenkaew, Orapan; Tang, Ming L.; Prakash, Edmond C.

    2000-03-01

    In this paper we present a new approach for apparel modeling based on voxel specifications that characterize control vertices and patch specifications. Our specification language is geared for robust apparel modeling by enforcing a strict control vertex coding via a combination of a static cross sectional slice and dynamic control polyhedron checking. Unlike most previous approach for apparel are not hard coded into the system. Instead we simply add suitable type definitions to the specification and define patterns to these types. We compile these specifications into a high performance volumetric apparel design system. Important components of our approach include efficient algorithms, for extraction of control vertices form slices of the volume and transformation of these vertices on sequences of such slices. Our system has been tested with the visible female system and we show a couple of examples generated using our approach.

  9. Volumetric measurements of pulmonary nodules: variability in automated analysis tools

    NASA Astrophysics Data System (ADS)

    Juluru, Krishna; Kim, Woojin; Boonn, William; King, Tara; Siddiqui, Khan; Siegel, Eliot

    2007-03-01

    Over the past decade, several computerized tools have been developed for detection of lung nodules and for providing volumetric analysis. Incidentally detected lung nodules have traditionally been followed over time by measurements of their axial dimensions on CT scans to ensure stability or document progression. A recently published article by the Fleischner Society offers guidelines on the management of incidentally detected nodules based on size criteria. For this reason, differences in measurements obtained by automated tools from various vendors may have significant implications on management, yet the degree of variability in these measurements is not well understood. The goal of this study is to quantify the differences in nodule maximum diameter and volume among different automated analysis software. Using a dataset of lung scans obtained with both "ultra-low" and conventional doses, we identified a subset of nodules in each of five size-based categories. Using automated analysis tools provided by three different vendors, we obtained size and volumetric measurements on these nodules, and compared these data using descriptive as well as ANOVA and t-test analysis. Results showed significant differences in nodule maximum diameter measurements among the various automated lung nodule analysis tools but no significant differences in nodule volume measurements. These data suggest that when using automated commercial software, volume measurements may be a more reliable marker of tumor progression than maximum diameter. The data also suggest that volumetric nodule measurements may be relatively reproducible among various commercial workstations, in contrast to the variability documented when performing human mark-ups, as is seen in the LIDC (lung imaging database consortium) study.

  10. Volumetric Velocity Fields Downstream of a 2-Bladed Turbine

    NASA Astrophysics Data System (ADS)

    Troolin, Daniel

    2013-11-01

    Tip vortices of axial-flow turbines are important in understanding the mean and turbulent characteristics of the wake. Volumetric 3-component velocimetry (V3V) was used to examine the flow downstream of a model two-bladed turbine in air. The turbine had a diameter of 177.8 mm and was powered by a motor operating at approximately 150 rpm. The measurement volume (50 × 50 × 20 mm) was positioned approximately 5 mm downstream of the blade tip, in order to examine the tip vortex structure. The V3V system utilized three 4MP cameras with 85 mm lenses positioned in a fixed triangular frame located at a distance of 450 mm from the back of the measurement volume. The illumination source was a 200 mJ dual-head pulsed Nd:YAG laser operating at 7.25 Hz and illuminating 1 micron olive oil droplets as tracer particles. The particle images were then analyzed to produce volumetric vector fields. The focus was placed on visualizing the complex interaction between the turbine tip vortices. Insights on the tip vortex dynamics and three dimensional characteristics of the wake flow will be discussed.

  11. A reduced volumetric expansion factor plot

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.

    1979-01-01

    A reduced volumetric expansion factor plot was constructed for simple fluids which is suitable for engineering computations in heat transfer. Volumetric expansion factors were found useful in correlating heat transfer data over a wide range of operating conditions including liquids, gases and the near critical region.

  12. A reduced volumetric expansion factor plot

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.

    1979-01-01

    A reduced volumetric expansion factor plot has been constructed for simple fluids which is suitable for engineering computations in heat transfer. Volumetric expansion factors have been found useful in correlating heat transfer data over a wide range of operating conditions including liquids, gases and the near critical region.

  13. Volumetric Video Compression for Interactive Playback★

    PubMed Central

    Sohn, Bong-Soo; Bajaj, Chandrajit; Siddavanahalli, Vinay

    2009-01-01

    We develop a volumetric video system which supports interactive browsing of compressed time-varying volumetric features (significant isosurfaces and interval volumes). Since the size of even one volumetric frame in a time-varying 3D data set is very large, transmission and on-line reconstruction are the main bottlenecks for interactive remote visualization of time-varying volume and surface data. We describe a compression scheme for encoding time-varying volumetric features in a unified way, which allows for on-line reconstruction and rendering. To increase the run-time decompression speed and compression ratio, we decompose the volume into small blocks and encode only the significant blocks that contribute to the isosurfaces and interval volumes. The results show that our compression scheme achieves high compression ratio with fast reconstruction, which is effective for client-side rendering of time-varying volumetric features. PMID:20072724

  14. Rapidly-steered single-element ultrasound for real-time volumetric imaging and guidance

    NASA Astrophysics Data System (ADS)

    Stauber, Mark; Western, Craig; Solek, Roman; Salisbury, Kenneth; Hristov, Dmitre; Schlosser, Jeffrey

    2016-03-01

    Volumetric ultrasound (US) imaging has the potential to provide real-time anatomical imaging with high soft-tissue contrast in a variety of diagnostic and therapeutic guidance applications. However, existing volumetric US machines utilize "wobbling" linear phased array or matrix phased array transducers which are costly to manufacture and necessitate bulky external processing units. To drastically reduce cost, improve portability, and reduce footprint, we propose a rapidly-steered single-element volumetric US imaging system. In this paper we explore the feasibility of this system with a proof-of-concept single-element volumetric US imaging device. The device uses a multi-directional raster-scan technique to generate a series of two-dimensional (2D) slices that were reconstructed into three-dimensional (3D) volumes. At 15 cm depth, 90° lateral field of view (FOV), and 20° elevation FOV, the device produced 20-slice volumes at a rate of 0.8 Hz. Imaging performance was evaluated using an US phantom. Spatial resolution was 2.0 mm, 4.7 mm, and 5.0 mm in the axial, lateral, and elevational directions at 7.5 cm. Relative motion of phantom targets were automatically tracked within US volumes with a mean error of -0.3+/-0.3 mm, -0.3+/-0.3 mm, and -0.1+/-0.5 mm in the axial, lateral, and elevational directions, respectively. The device exhibited a mean spatial distortion error of 0.3+/-0.9 mm, 0.4+/-0.7 mm, and -0.3+/-1.9 in the axial, lateral, and elevational directions. With a production cost near $1000, the performance characteristics of the proposed system make it an ideal candidate for diagnostic and image-guided therapy applications where form factor and low cost are paramount.

  15. Whole-cell, multicolor superresolution imaging using volumetric multifocus microscopy

    PubMed Central

    Hajj, Bassam; Wisniewski, Jan; El Beheiry, Mohamed; Chen, Jiji; Revyakin, Andrey; Wu, Carl; Dahan, Maxime

    2014-01-01

    Single molecule-based superresolution imaging has become an essential tool in modern cell biology. Because of the limited depth of field of optical imaging systems, one of the major challenges in superresolution imaging resides in capturing the 3D nanoscale morphology of the whole cell. Despite many previous attempts to extend the application of photo-activated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM) techniques into three dimensions, effective localization depths do not typically exceed 1.2 µm. Thus, 3D imaging of whole cells (or even large organelles) still demands sequential acquisition at different axial positions and, therefore, suffers from the combined effects of out-of-focus molecule activation (increased background) and bleaching (loss of detections). Here, we present the use of multifocus microscopy for volumetric multicolor superresolution imaging. By simultaneously imaging nine different focal planes, the multifocus microscope instantaneously captures the distribution of single molecules (either fluorescent proteins or synthetic dyes) throughout an ∼4-µm-deep volume, with lateral and axial localization precisions of ∼20 and 50 nm, respectively. The capabilities of multifocus microscopy to rapidly image the 3D organization of intracellular structures are illustrated by superresolution imaging of the mammalian mitochondrial network and yeast microtubules during cell division. PMID:25422417

  16. Axial Plane Optical Microscopy

    PubMed Central

    Li, Tongcang; Ota, Sadao; Kim, Jeongmin; Wong, Zi Jing; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

    2014-01-01

    We present axial plane optical microscopy (APOM) that can, in contrast to conventional microscopy, directly image a sample's cross-section parallel to the optical axis of an objective lens without scanning. APOM combined with conventional microscopy simultaneously provides two orthogonal images of a 3D sample. More importantly, APOM uses only a single lens near the sample to achieve selective-plane illumination microscopy, as we demonstrated by three-dimensional (3D) imaging of fluorescent pollens and brain slices. This technique allows fast, high-contrast, and convenient 3D imaging of structures that are hundreds of microns beneath the surfaces of large biological tissues. PMID:25434770

  17. Volumetric assessment of cerebral asymmetries in dogs.

    PubMed

    Siniscalchi, Marcello; Franchini, Delia; Pepe, Anna M; Sasso, Raffaella; Dimatteo, Salvatore; Vallortigara, Giorgio; Quaranta, Angelo

    2011-09-01

    In the present study we quantified volumetric brain asymmetries from computed tomography (CT) scans in 12 healthy dogs, using a semi-automated technique for assessing in vivo structure asymmetry. Volumetric assessment of asymmetrical cerebral lateral ventricle (ALV) was also investigated. Our results showed that seven dogs exhibited a right hemisphere significantly greater than the left, two dogs had a left-greater-than-right hemisphere asymmetry, and finally two dogs displayed no significant brain volumetric asymmetry. This right-biased hemispheric asymmetry supports data reported previously using post-mortem morphological studies in both dogs and other mammalian species.

  18. Why Students Fail at Volumetric Analysis.

    ERIC Educational Resources Information Center

    Pickering, Miles

    1979-01-01

    Investigates the reasons for students' failure in an introductory volumetric analysis course by analyzing test papers and judging them against a hypothetical ideal method of grading laboratory techniques. (GA)

  19. [A new volumetric infusion pump (author's transl)].

    PubMed

    Radke, J; Wencker, K H

    1977-06-01

    Our experience with a new volumetric infusion pump "Tekmar T 92" is reported. Over a period of months the reported advantages of the instrument were investigated on three separate units. Some few disadvantages for routine use were observed.

  20. Volumetric analysis of abdominal aortic aneurysm

    NASA Astrophysics Data System (ADS)

    Baskin, Kevin M.; Kusnick, Catherine A.; Shamsolkottabi, Susanne; Lang, Elvira V.; Corson, J. D.; Stanford, William; Thompson, Brad H.; Hoffman, Eric A.

    1996-04-01

    The purpose of this study was to develop a valid, reliable and accurate system of measurement of abdominal aortic aneurysms, using volumetric analysis of x-ray computed tomographic data. This study evaluates illustrative cases, and compares measurements of AAA phantoms, using standard 2D versus volumetric methods. To validate the volumetric analysis, four phantom aneurysms were constructed in a range of diameters (4.5 - 7.0 cm) which presents the greatest management challenge to the clinician. These phantoms were imaged using a Toshiba Xpress SX helical CT. Separate scans were obtained at conventional (10 mm X 10 mm) and thin slice (5 mm X 5 mm) collimations. The thin slices were reconstructed at 2 mm intervals. Data from each of the 96 scans were interpreted using a standard 2D approach, then analyzed using task-oriented volumetric software. We evaluate patient assessments, and compare greatest outer diameters of phantoms, by standard versus volumetric methods. Qualitative differences between solutions based on standard versus volumetric analysis of illustrative patient cases are substantial. Expert radiologists' standard measurements of phantom aneurysms are highly reliable (r2 equals 0.901 - 0.958; p < 0.001), but biased toward significant overestimation of aneurysm diameters in the range of clinical interest. For the same phantoms, volumetric analysis was both more reliable (r2 equals 0.986 - 0.996; p < 0.001), and more accurate, with no significant bias in the range of interest. Volumetric analysis promotes selection of more valid management strategies, by providing vital information not otherwise available, and allowing more reliable and accurate assessment of abdominal aortic aneurysms. It is particularly valuable in the presence of aortic tortuosity, vessel eccentricity, and uncertain involvement of critical vessels.

  1. Laser Based 3D Volumetric Display System

    DTIC Science & Technology

    1993-03-01

    Literature, Costa Mesa, CA July 1983. 3. "A Real Time Autostereoscopic Multiplanar 3D Display System", Rodney Don Williams, Felix Garcia, Jr., Texas...8217 .- NUMBERS LASER BASED 3D VOLUMETRIC DISPLAY SYSTEM PR: CD13 0. AUTHOR(S) PE: N/AWIU: DN303151 P. Soltan, J. Trias, W. Robinson, W. Dahlke 7...laser generated 3D volumetric images on a rotating double helix, (where the 3D displays are computer controlled for group viewing with the naked eye

  2. Survey of Volumetric Grid Generators

    NASA Technical Reports Server (NTRS)

    Woo, Alex; Volakis, John; Hulbert, Greg; Case, Jeff; Presley, Leroy L. (Technical Monitor)

    1994-01-01

    This document is the result of an Internet Survey of Volumetric grid generators. As such we have included information from only the responses which were sent to us. After the initial publication and posting of this survey, we would encourage authors and users of grid generators to send further information. Here is the initial query posted to SIGGRID@nas and the USENET group sci.physics.computational.fluid-dynamics. Date: Sun, 30 Jan 94 11:37:52 -0800 From: woo (Alex Woo x6010 227-6 rm 315) Subject: Info Sought for Survey of Grid Generators I am collecting information and reviews of both government sponsored and commercial mesh generators for large scientific calculations, both block structured and unstructured. If you send me a review of a mesh generator, please indicate its availability and cost. If you are a commercial concern with information on a product, please also include references for possible reviewers. Please email to woo@ra-next.arc.nasa.gov. I will post a summary and probably write a short note for the IEEE Antennas and Propagation Magazine. Alex Woo, MS 227-6 woo@ames.arc.nasa.gov NASA Ames Research Center NASAMAIL ACWOO Moffett Field, CA 94035-1000 SPANET 24582::W00 (415) 604-6010 (FAX) 604-4357 fhplabs,decwrl,uunet)!ames!woo Disclaimer: These are not official statements of NASA or EMCC. We did not include all the submitted text here. Instead we have created a database entry in the freely available and widely used BIBTeX format which has an Uniform Resource Locator (URL) field pointing to more details. The BIBTeX database is modeled after those available from the BIBNET project at University of Utah.

  3. GEOS axial booms

    NASA Technical Reports Server (NTRS)

    Schmidt, G. K.

    1979-01-01

    A booms and mechanisms subsystem was designed, developed, and qualified for the geostationary scientific satellite GEOS. Part of this subsystem consist of four axial booms consisting of one pair of 1 m booms and one pair of 2.5 m booms. Each of these booms is carrying one bird cage electric field sensor. Alignment accuracy requirements led to a telescopic type solution. Deployment is performed by pressurized nitrogen. At deployment in orbit two of these booms showed some anomalies and one of these two deployed only about 80%. Following this malfunction a detailed failure investigation was performed resulting in a design modification of some critical components as release mechanism, guide sleeves of the telescopic elements, and pressure system.

  4. Intervertebral disc segmentation and volumetric reconstruction from peripheral quantitative computed tomography imaging.

    PubMed

    Wong, Alexander; Mishra, Akshaya; Yates, Justin; Fieguth, Paul; Clausi, David A; Callaghan, Jack P

    2009-11-01

    An automatic system for segmenting and constructing volumetric representations of excised intervertebral discs from peripheral quantitative computed tomography (PQCT) imagery is presented. The system is designed to allow for automatic quantitative analysis of progressive herniation damage to the intervertebral discs under flexion/extension motions combined with a compressive load. Automatic segmentation and volumetric reconstruction of intervertebral disc from PQCT imagery is a very challenging problem due to factors such as streak artifacts and unclear material density separation between contrasted intervertebral disc and surrounding bone in the PQCT imagery, as well as the formation of multiple contrasted regions under axial scans. To address these factors, a novel multiscale level set approach based on the Mumford-Shah energy functional in iterative bilateral scale space is employed to segment the intervertebral disc regions from the PQCT imagery. A Delaunay triangulation is then performed based on the set of points associated with the intervertebral disc regions to construct the volumetric representation of the intervertebral disc. Experimental results show that the proposed system achieves segmentation and volumetric reconstructions of intervertebral discs with mean absolute distance error below 0.8 mm when compared to ground truth measurements. The proposed system is currently in operational use as a visualization tool for studying progressive intervertebral disc damage.

  5. Axial movements in ideomotor apraxia

    PubMed Central

    Poeck, K; Lehmkuhl, G; Willmes, K

    1982-01-01

    Non-symbolic axial movements were examined and compared to oral and limb movements in a group of 60 aphasic patients (15 of each major subgroup) with exclusively left-sided brain damage. The contention in the literature that axial movements are preserved in patients with ideomotor limb apraxia was not confirmed. PMID:6186771

  6. Axial disease in psoriatic arthritis.

    PubMed

    Gladman, Dafna D

    2007-12-01

    The definition of axial disease in psoriatic arthritis has varied from isolated unilateral grade 2 sacroiliitis to criteria similar to those used for ankylosing spondylitis. Depending on the definition used, the prevalence of axial disease varies from 25% to 70% of patients with psoriatic arthritis. This article reviews the prevalence, clinical and radiologic features, pathogenesis, prognosis, and treatment of psoriatic spondylitis.

  7. Volumetric structured illumination microscopy enabled by a tunable-focus lens.

    PubMed

    Hinsdale, Taylor; Malik, Bilal H; Olsovsky, Cory; Jo, Javier A; Maitland, Kristen C

    2015-11-01

    We present a mechanical-scan-free method for volumetric imaging of biological tissue. The optical sectioning is provided by structured illumination, and the depth of the imaging plane is varied using an electrically tunable-focus lens. We characterize and evaluate the ability of this axial-scanning mechanism in structured illumination microscopy and demonstrate its ability to perform subcellular resolution imaging in oral mucosa ex vivo. The proposed mechanism can potentially convert any wide-field microscope to a 3D-imaging platform without the need for mechanical scanning of imaging optics and/or sample.

  8. Volumetric structured illumination microscopy enabled by a tunable-focus lens

    PubMed Central

    Hinsdale, Taylor; Malik, Bilal H.; Olsovsky, Cory; Jo, Javier A.; Maitland, Kristen C.

    2016-01-01

    We present a mechanical-scan-free method for volumetric imaging of biological tissue. The optical sectioning is provided by structured illumination, and the depth of the imaging plane is varied using an electrically tunable-focus lens. We characterize and evaluate the ability of this axial-scanning mechanism in structured illumination microscopy and demonstrate its ability to perform subcellular resolution imaging in oral mucosa ex vivo. The proposed mechanism can potentially convert any wide-field microscope to a 3D-imaging platform without the need for mechanical scanning of imaging optics and/or sample. PMID:26512489

  9. Three-axis digital holographic microscopy for high speed volumetric imaging.

    PubMed

    Saglimbeni, F; Bianchi, S; Lepore, A; Di Leonardo, R

    2014-06-02

    Digital Holographic Microscopy allows to numerically retrieve three dimensional information encoded in a single 2D snapshot of the coherent superposition of a reference and a scattered beam. Since no mechanical scans are involved, holographic techniques have a superior performance in terms of achievable frame rates. Unfortunately, numerical reconstructions of scattered field by back-propagation leads to a poor axial resolution. Here we show that overlapping the three numerical reconstructions obtained by tilted red, green and blue beams results in a great improvement over the axial resolution and sectioning capabilities of holographic microscopy. A strong reduction in the coherent background noise is also observed when combining the volumetric reconstructions of the light fields at the three different wavelengths. We discuss the performance of our technique with two test objects: an array of four glass beads that are stacked along the optical axis and a freely diffusing rod shaped E.coli bacterium.

  10. A volumetric flask as a projector

    NASA Astrophysics Data System (ADS)

    Limsuwan, P.; Asanithi, P.; Thongpool, V.; Piriyawong, V.; Limsuwan, S.

    2012-03-01

    A lens based on liquid in the confined volume of a volumetric flask was presented as a potential projector to observe microscopic floating organisms or materials. In this experiment, a mosquito larva from a natural pond was selected as a demonstration sample. By shining a light beam from a laser pointer of any visible wavelength through the volumetric flask filled with liquid, the movements of floating objects were clearly observed on a screen. The magnification was simply controlled by changing either the volume of the flask or the distance of the screen from the flask.

  11. Nonequilibrium volumetric response of shocked polymers

    SciTech Connect

    Clements, B E

    2009-01-01

    Polymers are well known for their non-equilibrium deviatoric behavior. However, investigations involving both high rate shock experiments and equilibrium measured thermodynamic quantities remind us that the volumetric behavior also exhibits a non-equilibrium response. Experiments supporting the notion of a non-equilibrium volumetric behavior will be summarized. Following that discussion, a continuum-level theory is proposed that will account for both the equilibrium and non-equilibrium response. Upon finding agreement with experiment, the theory is used to study the relaxation of a shocked polymer back towards its shocked equilibrium state.

  12. Axial gap rotating electrical machine

    DOEpatents

    None

    2016-02-23

    Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.

  13. Study of axial magnetic effect

    SciTech Connect

    Braguta, Victor; Chernodub, M. N.; Goy, V. A.; Landsteiner, K.; Ulybyshev, M.

    2016-01-22

    The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T{sup 2} behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction.

  14. Appropriate management of axial spondyloarthritis.

    PubMed

    LaSalle, Sean P; Deodhar, Atul A

    2007-10-01

    The management of axial spondyloarthritis includes a structured baseline assessment of the disease and follow-up of treatment efficacy using validated instruments. The treatment will depend on the severity and predominant manifestations of the disease. The cornerstone of management remains physical therapy and nonsteroidal anti-inflammatory drugs. Disease-modifying antirheumatic drugs such as sulfasalazine have shown efficacy only in treating peripheral arthritis, whereas thalidomide and pamidronate have shown some efficacy in treating axial inflammation. Anti-tumor necrosis factor-alpha agents are an efficacious option for treating signs and symptoms of axial disease, peripheral arthritis, and enthesitis, and for improving functional outcomes. They have not shown efficacy in reducing radiographic progression in axial disease. Recent evidence suggests that the new bone formation in ankylosing spondylitis may be due to upregulation of Wnt signaling in the osteoblastic pathway secondary to low serum DKK-1 levels, which are further suppressed by tumor necrosis factor inhibitor therapy.

  15. Dissipative axial inflation

    NASA Astrophysics Data System (ADS)

    Notari, Alessio; Tywoniuk, Konrad

    2016-12-01

    We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term phi/fγ F ~F, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density ρR, which can lead to inflation without the need of a flat potential. We analyze the system, for momenta k smaller than the cutoff fγ, including the backreaction numerically. We consider the evolution from a given static initial condition and explicitly show that, if fγ is smaller than the field excursion phi0 by about a factor of at least Script O (20), there is a friction effect which turns on before the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of perturbations, scalars and tensors. Such oscillations have a period of 4-5 efolds and an amplitude which is typically less than a few percent and decreases linearly with fγ. We also stress that the curvature perturbation on uniform density slices should be sensitive to slow-roll parameters related to ρR rather than dot phi2/2 and we discuss the existence of friction terms acting on the perturbations, although we postpone a calculation of the power spectrum and of non-gaussianity to future work and we simply define and compute suitable slow roll parameters. Finally we stress that this scenario may be realized in the axion case, if the coupling 1/fγ to U(1) (photons) is much larger than the coupling 1/fG to non-abelian gauge fields (gluons), since the latter sets the range of the potential and therefore the maximal allowed phi0~ fG.

  16. Volumetric applications for spiral CT in the thorax

    NASA Astrophysics Data System (ADS)

    Rubin, Geoffrey D.; Napel, Sandy; Leung, Ann N.

    1994-05-01

    Spiral computed tomography (CT) is a new technique for rapidly acquiring volumetric data within the body. By combining a continuous gantry rotation and table feed, it is possible to image the entire thorax within a single breath-hold. This eliminates the ventilatory misregistration seen with conventional thoracic CT, which can result in small pulmonary lesions being undetected. An additional advantage of a continuous data set is that axial sections can be reconstructed at arbitrary intervals along the spiral path, resulting in the generation of overlapping sections which diminish partial volume effects resulting from lesions that straddle adjacent sections. The rapid acquisition of spiral CT enables up to a 50% reduction in the total iodinated contrast dose required for routine thoracic CT scanning. This can be very important for imaging patients with cardiac and renal diseases and could reduce the cost of thoracic CT scanning. Alternatively, by combining a high flow peripheral intravenous iodinated contrast injection with a spiral CT acquisition, it is possible to obtain images of the vasculature, which demonstrate pulmonary arterial thrombi, aortic aneurysms and dissections, and congenital vascular anomalies in detail previously unattainable without direct arterial access.

  17. A Volumetric Flask as a Projector

    ERIC Educational Resources Information Center

    Limsuwan, P.; Asanithi, P.; Thongpool, V.; Piriyawong, V.; Limsuwan, S.

    2012-01-01

    A lens based on liquid in the confined volume of a volumetric flask was presented as a potential projector to observe microscopic floating organisms or materials. In this experiment, a mosquito larva from a natural pond was selected as a demonstration sample. By shining a light beam from a laser pointer of any visible wavelength through the…

  18. Indexing Volumetric Shapes with Matching and Packing.

    PubMed

    Koes, David Ryan; Camacho, Carlos J

    2015-04-01

    We describe a novel algorithm for bulk-loading an index with high-dimensional data and apply it to the problem of volumetric shape matching. Our matching and packing algorithm is a general approach for packing data according to a similarity metric. First an approximate k-nearest neighbor graph is constructed using vantage-point initialization, an improvement to previous work that decreases construction time while improving the quality of approximation. Then graph matching is iteratively performed to pack related items closely together. The end result is a dense index with good performance. We define a new query specification for shape matching that uses minimum and maximum shape constraints to explicitly specify the spatial requirements of the desired shape. This specification provides a natural language for performing volumetric shape matching and is readily supported by the geometry-based similarity search (GSS) tree, an indexing structure that maintains explicit representations of volumetric shape. We describe our implementation of a GSS tree for volumetric shape matching and provide a comprehensive evaluation of parameter sensitivity, performance, and scalability. Compared to previous bulk-loading algorithms, we find that matching and packing can construct a GSS-tree index in the same amount of time that is denser, flatter, and better performing, with an observed average performance improvement of 2X.

  19. Indexing Volumetric Shapes with Matching and Packing

    PubMed Central

    Koes, David Ryan; Camacho, Carlos J.

    2014-01-01

    We describe a novel algorithm for bulk-loading an index with high-dimensional data and apply it to the problem of volumetric shape matching. Our matching and packing algorithm is a general approach for packing data according to a similarity metric. First an approximate k-nearest neighbor graph is constructed using vantage-point initialization, an improvement to previous work that decreases construction time while improving the quality of approximation. Then graph matching is iteratively performed to pack related items closely together. The end result is a dense index with good performance. We define a new query specification for shape matching that uses minimum and maximum shape constraints to explicitly specify the spatial requirements of the desired shape. This specification provides a natural language for performing volumetric shape matching and is readily supported by the geometry-based similarity search (GSS) tree, an indexing structure that maintains explicit representations of volumetric shape. We describe our implementation of a GSS tree for volumetric shape matching and provide a comprehensive evaluation of parameter sensitivity, performance, and scalability. Compared to previous bulk-loading algorithms, we find that matching and packing can construct a GSS-tree index in the same amount of time that is denser, flatter, and better performing, with an observed average performance improvement of 2X. PMID:26085707

  20. Uncertainty quantification in volumetric Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sayantan; Charonko, John; Vlachos, Pavlos

    2016-11-01

    Particle Image Velocimetry (PIV) uncertainty quantification is challenging due to coupled sources of elemental uncertainty and complex data reduction procedures in the measurement chain. Recent developments in this field have led to uncertainty estimation methods for planar PIV. However, no framework exists for three-dimensional volumetric PIV. In volumetric PIV the measurement uncertainty is a function of reconstructed three-dimensional particle location that in turn is very sensitive to the accuracy of the calibration mapping function. Furthermore, the iterative correction to the camera mapping function using triangulated particle locations in space (volumetric self-calibration) has its own associated uncertainty due to image noise and ghost particle reconstructions. Here we first quantify the uncertainty in the triangulated particle position which is a function of particle detection and mapping function uncertainty. The location uncertainty is then combined with the three-dimensional cross-correlation uncertainty that is estimated as an extension of the 2D PIV uncertainty framework. Finally the overall measurement uncertainty is quantified using an uncertainty propagation equation. The framework is tested with both simulated and experimental cases. For the simulated cases the variation of estimated uncertainty with the elemental volumetric PIV error sources are also evaluated. The results show reasonable prediction of standard uncertainty with good coverage.

  1. A Volumetric Flask as a Projector

    ERIC Educational Resources Information Center

    Limsuwan, P.; Asanithi, P.; Thongpool, V.; Piriyawong, V.; Limsuwan, S.

    2012-01-01

    A lens based on liquid in the confined volume of a volumetric flask was presented as a potential projector to observe microscopic floating organisms or materials. In this experiment, a mosquito larva from a natural pond was selected as a demonstration sample. By shining a light beam from a laser pointer of any visible wavelength through the…

  2. Differential occupation of axial morphospace.

    PubMed

    Ward, Andrea B; Mehta, Rita S

    2014-02-01

    The postcranial system is composed of the axial and appendicular skeletons. The axial skeleton, which consists of serially repeating segments commonly known as vertebrae, protects and provides leverage for movement of the body. Across the vertebral column, much numerical and morphological diversity can be observed, which is associated with axial regionalization. The present article discusses this basic diversity and the early developmental mechanisms that guide vertebral formation and regionalization. An examination of vertebral numbers across the major vertebrate clades finds that actinopterygian and chondrichthyan fishes tend to increase vertebral number in the caudal region whereas Sarcopterygii increase the number of vertebrae in the precaudal region, although exceptions to each trend exist. Given the different regions of axial morphospace that are occupied by these groups, differential developmental processes control the axial patterning of actinopterygian and sarcopterygian species. It is possible that, among a variety of factors, the differential selective regimes for aquatic versus terrestrial locomotion have led to the differential use of axial morphospace in vertebrates.

  3. Performance comparisons of planar and volumetric observers for lesion detection in PET scanning

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Seung; Kinahan, Paul E.; Lartizien, Carole; Comtat, Claude; Lewellen, Tom K.

    2003-05-01

    This work presents initial results of comparisons between planar and volumetric observer detection task performances for both human and model observers. Positron Emission Tomography (PET) imaging acquires and reconstructs tomographic images as contiguous volumetric (3D) images. Consequently physicians typically interpret these images by searching the image volume using linked orthogonal planar images in the three standard orientations (transverse, sagittal, and coronal). Most of observer studies, however, have typically used planar images for evaluation. For human observer ROC studies, an observer scoring tool, similar to the display tool being used in clinical PET oncology imaging, has been developed. For model observer studies the non-prewhitening matched filter (NPWMF) and the channelized Hotelling observer (CHO) were used to compute detectabilities as figures-of-merit for class separations. For the volumetric (3D)model observers, the entire image volume is used with appropriate 3D templates. For the planar (2D) model observers the transaxial plane centered on the target sphere is extracted and analyzed using 2D templates. Multiple realizations were generated using a non-Monte Carlo analytic simulator for feasible amount of simulation time and statistically accurate noise properties. For comparisons, the correlations between each model observer and human observer performance are computed. The result showed that 3D model observers have a higher correlation with human observers than 2D observers do when axial smoothing is not applied. With axial smoothing, however, the correlation of 2D model observers in general increased to the level of 3D model observer correlations with the human observer.

  4. Thermoacoustic mixture separation with an axial temperature gradient.

    PubMed

    Geller, D A; Swift, G W

    2009-05-01

    The theory of thermoacoustic mixture separation is extended to include the effect of a nonzero axial temperature gradient. The analysis yields a new term in the second-order mole flux that is proportional to the temperature gradient and to the square of the volumetric velocity and is independent of the phasing of the wave. Because of this new term, thermoacoustic separation stops at a critical temperature gradient and changes direction above that gradient. For a traveling wave, this gradient is somewhat higher than that predicted by a simple four-step model. An experiment tests the theory for temperature gradients from 0 to 416 K/m in 50-50 He-Ar mixtures.

  5. Thermoacoustic mixture separation with an axial temperature gradient

    SciTech Connect

    Geller, Drew W; Swift, Gregory A

    2008-01-01

    The theory of thermoacoustic mixture separation is extended to include the effect of a nonzero axial temperature gradient. The analysis yields a new term in the second-order mole flux that is proportional to the temperature gradient and to the square of the volumetric velocity and is independent of the phasing of the wave. Because of this new term, thermoacoustic separation stops at a critical temperature gradient and changes direction above that gradient. For a traveling wave, this gradient is somewhat higher than that predicted by a simple four-step model. An experiment tests the theory for temperature gradients from 0 to 416 K/m in 50-50 He-Ar mixtures.

  6. JPEG2000 Part 10: volumetric imaging

    NASA Astrophysics Data System (ADS)

    Schelkens, Peter; Brislawn, Christopher M.; Barbarien, Joeri; Munteanu, Adrian; Cornelis, Jan P.

    2003-11-01

    Recently, the JPEG2000 committee (ISO/IEC JTC1/SC29/WG1) decided to start up a new standardization activity to support the encoding of volumetric and floating-point data sets: Part 10 - Coding Volumetric and Floating-point Data (JP3D). This future standard will support functionalities like resolution and quality scalability and region-of-interest coding, while exploiting the entropy in the additional third dimension to improve the rate-distortion performance. In this paper, we give an overview of the markets and application areas targeted by JP3D, the imposed requirements and the considered algorithms with a specific focus on the realization of the region-of-interest functionality.

  7. VOLUMETRIC POLYMERIZATION SHRINKAGE OF CONTEMPORARY COMPOSITE RESINS

    PubMed Central

    Nagem, Halim; Nagem, Haline Drumond; Francisconi, Paulo Afonso Silveira; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Coutinho, Kennedy Queiroz

    2007-01-01

    The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (á=0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01) and Definite (1.89±0.01) shrank significantly less than the other composite resins. SureFil (2.01±0.06), Filtek Z250 (1.99±0.03), and Fill Magic (2.02±0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation. PMID:19089177

  8. A volumetric data system for environmental robotics

    SciTech Connect

    Tourtellott, J.

    1994-12-31

    A three-dimensional, spatially organized or volumetric data system provides an effective means for integrating and presenting environmental sensor data to robotic systems and operators. Because of the unstructed nature of environmental restoration applications, new robotic control strategies are being developed that include environmental sensors and interactive data interpretation. The volumetric data system provides key features to facilitate these new control strategies including: integrated representation of surface, subsurface and above-surface data; differentiation of mapped and unmapped regions in space; sculpting of regions in space to best exploit data from line-of-sight sensors; integration of diverse sensor data (for example, dimensional, physical/geophysical, chemical, and radiological); incorporation of data provided at different spatial resolutions; efficient access for high-speed visualization and analysis; and geometric modeling tools to update a {open_quotes}world model{close_quotes} of an environment. The applicability to underground storage tank remediation and buried waste site remediation are demonstrated in several examples. By integrating environmental sensor data into robotic control, the volumetric data system will lead to safer, faster, and more cost-effective environmental cleanup.

  9. Feasibility study on dosimetry verification of volumetric-modulated arc therapy-based total marrow irradiation.

    PubMed

    Liang, Yun; Kim, Gwe-Ya; Pawlicki, Todd; Mundt, Arno J; Mell, Loren K

    2013-03-04

    The purpose of this study was to develop dosimetry verification procedures for volumetric-modulated arc therapy (VMAT)-based total marrow irradiation (TMI). The VMAT based TMI plans were generated for three patients: one child and two adults. The planning target volume (PTV) was defined as bony skeleton, from head to mid-femur, with a 3 mm margin. The plan strategy similar to published studies was adopted. The PTV was divided into head and neck, chest, and pelvic regions, with separate plans each of which is composed of 2-3 arcs/fields. Multiple isocenters were evenly distributed along the patient's axial direction. The focus of this study is to establish a dosimetry quality assurance procedure involving both two-dimensional (2D) and three-dimensional (3D) volumetric verifications, which is desirable for a large PTV treated with multiple isocenters. The 2D dose verification was performed with film for gamma evaluation and absolute point dose was measured with ion chamber, with attention to the junction between neighboring plans regarding hot/cold spots. The 3D volumetric dose verification used commercial dose reconstruction software to reconstruct dose from electronic portal imaging devices (EPID) images. The gamma evaluation criteria in both 2D and 3D verification were 5% absolute point dose difference and 3 mm of distance to agreement. With film dosimetry, the overall average gamma passing rate was 98.2% and absolute dose difference was 3.9% in junction areas among the test patients; with volumetric portal dosimetry, the corresponding numbers were 90.7% and 2.4%. A dosimetry verification procedure involving both 2D and 3D was developed for VMAT-based TMI. The initial results are encouraging and warrant further investigation in clinical trials.

  10. Thermophoresis of Axially Symmetric Bodies

    DTIC Science & Technology

    2007-11-02

    Sweden Abstract. Thermophoresis of axially symmetric bodies is investigated to first order in the Knudsen-mimber, Kn. The study is made in the limit...derived. Asymptotic solutions are studied. INTRODUCTION Thermophoresis as a phenomenon has been known for a long time, and several authors have approached

  11. Axial pumps for propulsion systems

    NASA Technical Reports Server (NTRS)

    Huppert, M. C.; Rothe, K.

    1974-01-01

    The development of axial flow hydrogen pumps is examined. The design features and the performance data obtained during the course of the development programs are discussed. The problems created by the pump characteristics are analyzed. Graphs of four stage pump performance for various turbine blade configurations are developed. The characteristics and performance of a variety of pumps are included.

  12. Axial structure of the nucleon

    SciTech Connect

    Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner

    2002-01-01

    We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.

  13. Gas sorption and the consequent volumetric and permeability change of coal

    NASA Astrophysics Data System (ADS)

    Lin, Wenjuan

    in the injection gas, the greater the amount of total adsorption. Volumetric strain followed the same trend as the amount of adsorption with pressure and injection gas composition. Permeability showed opposite behaviors, decreasing with the increase of pressure and the percentage of CO2 in the injection gas. The experimental adsorption, volumetric strain, and permeability data were analyzed to investigate the numerical correlations between gas sorption, sorption-induced volumetric strain and permeability, and pressure and injection gas composition. The relationship between the amount of adsorption and pressure for pure gases (CO2 and N2) were readily represented by parametric isotherm models, such as Langmuir and the N-layer BET equations. Modeling efforts of multicomponent adsorption included predicting amount of adsorption and adsorbed phase composition based on the extended Langmuir equations and the ideal adsorbed solution model. Activity coefficients of the components in the adsorbed phase were computed based on the real adsorbed solution model and the ABC excess Gibbs free energy model. Algorithms for modeling the CO 2/N2-Coal system were developed, and the constraints and strength of each model were discussed. The experimental volumetric strain was found to be linearly proportional to the total amount of adsorption and independent of the injection gas composition. The permeability reduction could not be readily correlated by the models in the literature unless the change of other coal properties (bulk modulus, axial constrained modulus, etc.) due to gas sorption was incorporated. The sorption, volumetric strain, and permeability data collected in this study can be used for comparison by other researchers conducting similar studies. The algorithms of sorption modeling and the correlations developed in this study are readily incorporated into the simulation of enhanced coalbed methane recovery and CO2 sequestration in coalbeds. (Abstract shortened by UMI.)

  14. Implementation and characterization of a 320-slice volumetric CT scanner for simulation in radiation oncology.

    PubMed

    Coolens, C; Breen, S; Purdie, T G; Owrangi, A; Publicover, J; Bartolac, S; Jaffray, D A

    2009-11-01

    Effective target definition and broad employment of treatment response assessment with dynamic contrast-enhanced CT in radiation oncology requires increased speed and coverage for use within a single bolus injection. To this end, a novel volumetric CT scanner (Aquilion One, Toshiba, Tochigi Pref., Japan) has been installed at the Princess Margaret Hospital for implementation into routine CT simulation. This technology offers great advantages for anatomical and functional imaging in both scan speed and coverage. The aim of this work is to investigate the system's imaging performance and quality as well as CT quantification accuracy which is important for radiotherapy dose calculations. The 320-slice CT scanner uses a 160 mm wide-area (2D) solid-state detector design which provides the possibility to acquire a volumetric axial length of 160 mm without moving the CT couch. This is referred to as "volume" and can be scanned with a rotation speed of 0.35-3 s. The scanner can also be used as a 64-slice CT scanner and perform conventional (axial) and helical acquisitions with collimation ranges of 1-32 and 16-32 mm, respectively. Commissioning was performed according to AAPM Reports TG 66 and 39 for both helical and volumetric imaging. Defrise and other cone-beam image analysis tests were performed. Overall, the imaging spatial resolution and geometric efficiency (GE) were found to be very good (>10 lp/mm, <1 mm spatial integrity and GE160 mm=85%) and within the AAPM guidelines as well as IEC recommendations. Although there is evidence of some cone-beam artifacts when scanning the Defrise phantom, image quality was found to be good and sufficient for treatment planning (soft tissue noise <10 HU). Measurements of CT number stability and contrast-to-noise values across the volume indicate clinically acceptable scan accuracy even at the field edge. Initial experience with this exciting new technology confirms its accuracy for routine CT simulation within radiation oncology

  15. Implementation and characterization of a 320-slice volumetric CT scanner for simulation in radiation oncology

    SciTech Connect

    Coolens, C.; Breen, S.; Purdie, T. G.; Owrangi, A.; Publicover, J.; Bartolac, S.; Jaffray, D. A.

    2009-11-15

    Purpose: Effective target definition and broad employment of treatment response assessment with dynamic contrast-enhanced CT in radiation oncology requires increased speed and coverage for use within a single bolus injection. To this end, a novel volumetric CT scanner (Aquilion One, Toshiba, Tochigi Pref., Japan) has been installed at the Princess Margaret Hospital for implementation into routine CT simulation. This technology offers great advantages for anatomical and functional imaging in both scan speed and coverage. The aim of this work is to investigate the system's imaging performance and quality as well as CT quantification accuracy which is important for radiotherapy dose calculations. Methods: The 320-slice CT scanner uses a 160 mm wide-area (2D) solid-state detector design which provides the possibility to acquire a volumetric axial length of 160 mm without moving the CT couch. This is referred to as ''volume'' and can be scanned with a rotation speed of 0.35-3 s. The scanner can also be used as a 64-slice CT scanner and perform conventional (axial) and helical acquisitions with collimation ranges of 1-32 and 16-32 mm, respectively. Commissioning was performed according to AAPM Reports TG 66 and 39 for both helical and volumetric imaging. Defrise and other cone-beam image analysis tests were performed. Results: Overall, the imaging spatial resolution and geometric efficiency (GE) were found to be very good (>10 lp/mm, <1 mm spatial integrity and GE{sub 160mm}=85%) and within the AAPM guidelines as well as IEC recommendations. Although there is evidence of some cone-beam artifacts when scanning the Defrise phantom, image quality was found to be good and sufficient for treatment planning (soft tissue noise <10 HU). Measurements of CT number stability and contrast-to-noise values across the volume indicate clinically acceptable scan accuracy even at the field edge. Conclusions: Initial experience with this exciting new technology confirms its accuracy for

  16. Volumetric Near-Field Microwave Plasma Generation

    NASA Technical Reports Server (NTRS)

    Exton, R. J.; Balla, R. Jeffrey; Herring, G. C.; Popovic, S.; Vuskovic, L.

    2003-01-01

    A periodic series of microwave-induced plasmoids is generated using the outgoing wave from a microwave horn and the reflected wave from a nearby on-axis concave reflector. The plasmoids are spaced at half-wavelength separations according to a standing-wave pattern. The plasmoids are enhanced by an effective focusing in the near field of the horn (Fresnel region) as a result of a diffractive narrowing. Optical imaging, electron density, and rotational temperature measurements characterize the near field plasma region. Volumetric microwave discharges may have application to combustion ignition in scramjet engines.

  17. Axially grooved heat pipes - 1976

    NASA Technical Reports Server (NTRS)

    Brennan, P. J.; Kroliczek, E. J.; Jen, H.; Mcintosh, R.

    1977-01-01

    This paper summarizes the 'state-of-the-art' of axially grooved heat pipes. Applications are identified and the related heat pipe design and performance are defined. Recent developments in the analysis, design and fabrication of axially grooved hardware are also discussed. A mathematical model which predicts the hydrodynamic behavior and accounts for liquid recession, liquid/vapor shear interaction and 1-g puddle flow is also presented. Performance data for various fluids in the 100-500 K range is compared to predictions from the Groove Analysis Program (GAP). Finally, a simplified closed form solution which accounts for gravity effects, self-priming and composite pumping by the grooves as well as all of the hydrodynamic losses is also discussed.

  18. Ultrasonic measurement of axial stress

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.; Chern, E. J.

    1982-01-01

    The theory of acoustic propagation in strained media is examined, with particular emphasis on rod (bolt) geometries. The continuous wave (CW) approach is the basis of the study, and the theory is developed from a frequency domain analysis standpoint in order to obtain an applied stress/normalized frequency shift relationship. CW measurements may be influenced by such factors as propagation effects, mode conversion, frequency, material properties, and geometry. After the first loading cycle, axial stress measurements for a preloading with an initial frequency of 4.995 36 MHz dropped to 4.989 19 MHz, indicating a 6.17 kHz change. CW and pseudo-CW ultrasonic techniques are found to be reliable for axial stress measurements, and acoustic attenuation measurements correlated to residual stress fields may possibly involve transducer phase cancellation. It is thus concluded that signal drop is an artifact of the transducer directivity, rather than an actual acoustic power decrease.

  19. [Axial spondyloarthritis and ankylosing spondylitis].

    PubMed

    Nordström, Dan; Kauppi, Markku

    2010-01-01

    Current classification criteria for ankylosing spondylitis do not allow diagnosis before radiographic changes are visible in sacroiliacal joints. The the new axial spondyloarthropathy (SpA) criteria include axial SpA without radiographic changes as well as established ankylosing spondylitis, recognizing them as a continuum of the same disease. This is of major importance as the burden of early SpA is comparable to that of later stage disease. Diagnosis relies on inflammatory MRI findings which is the most significant change compared to earlier criteria. Emerging data on the efficacy of tumor necrosis factor (TNF) alpha blocking therapies already in early but also in established disease have given new promising alternatives for treatment of this often very cumbersome disease, that rarely responds to classic DMARDs.

  20. Performance of the Volumetric Diffusive Respirator at Altitude

    DTIC Science & Technology

    2014-08-18

    AFRL-SA-WP-SR-2014-0020 Performance of the Volumetric Diffusive Respirator at Altitude Dario Rodriquez, MSc1; Tyler Britton, RRT2...the Volumetric Diffusive Respirator at Altitude 5a. CONTRACT NUMBER FA8650-12-2-6B012 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...volumetric diffusive respirator is a pneumatic ventilator used by the U.S. Army Burn Team and the U.S. Air Force Lung Team for patients with hypoxemic

  1. Analysis of axial flow turbines

    NASA Astrophysics Data System (ADS)

    Garg, V. K.

    A variety of steady and time-dependent, two and three dimensional numerical techniques for axial-flow turbulent design and analysis is reviewed. Meridional flow solutions are discussed, including the streamline curvature method, the matrix method, and finite element methods. Blade-to-blade flow solutions are considered, including singularity methods, field methods, and transonic blade-to-blade calculations. Three-dimensional flow solutions are briefly examined.

  2. BOREAS HYD-1 Volumetric Soil Moisture Data

    NASA Technical Reports Server (NTRS)

    Cuenca, Richard H.; Kelly, Shaun F.; Stangel, David E.; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-1 team made measurements of volumetric soil moisture at the Southern Study Area (SSA) and Northern Study Area (NSA) tower flux sites in 1994 and at selected tower flux sites in 1995-97. Different methods were used to collect these measurements, including neutron probe and manual and automated Time Domain Reflectometry (TDR). In 1994, the measurements were made every other day at the NSA-OJP (Old Jack Pine), NSA-YJP (Young Jack Pine), NSA-OBS (Old Black Spruce), NSA-Fen, SSA-OJP, SSA-YJP, SSA-Fen, SSA-YA (Young Aspen), and SSA-OBS sites. In 1995-97, when automated equipment was deployed at NSA-OJP, NSA-YJP, NSA-OBS, SSA-OBS, and SSA-OA (Old Aspen), the measurements were made as often as every hour. The data are stored in tabular ASCII files. The volumetric soil moisture data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  3. Integral volumetric imaging using decentered elemental lenses.

    PubMed

    Sawada, Shimpei; Kakeya, Hideki

    2012-11-05

    This paper proposes a high resolution integral imaging system using a lens array composed of non-uniform decentered elemental lenses. One of the problems of integral imaging is the trade-off relationship between the resolution and the number of views. When the number of views is small, motion parallax becomes strongly discrete to maintain the viewing angle. In order to overcome this trade-off, the proposed method uses the elemental lenses whose size is smaller than that of the elemental images. To keep the images generated by the elemental lenses at constant depth, the lens array is designed so that the optical centers of elemental lenses may be located in the centers of elemental images, not in the centers of elemental lenses. To compensate optical distortion, new image rendering algorithm is developed so that undistorted 3D image may be presented with a non-uniform lens array. The proposed design of lens array can be applied to integral volumetric imaging, where display panels are layered to show volumetric images in the scheme of integral imaging.

  4. Volumetric display with holographic multi-photon excitations

    NASA Astrophysics Data System (ADS)

    Hayasaki, Yoshio; Kumagai, Kota

    2016-10-01

    We developed a volumetric display with holographic two- and multi-photon excitations using a computer-generated hologram displayed on a liquid crystal spatial light modulator. The holographic technique has advantages of increasing the number of voxels of the volumetric graphics per unit time, increasing the total input energy to the volumetric display because the maximum energy incident at a point in the display material is limited by the damage threshold, and controlling the size, shape and spatial position of voxels. We demonstrated a volumetric display with stacked multi-color fluorescence plates.

  5. Golimumab for treatment of axial spondyloarthritis.

    PubMed

    Rios Rodriguez, Valeria; Poddubnyy, Denis

    2016-02-01

    Axial spondyloarthritis comprises two forms: nonradiographic (nonradiographic axial spondyloarthritis) and radiographic (better known as ankylosing spondylitis), which are often considered as two stages of one disease. Historically, all currently available TNF-α inhibitors were first investigated in ankylosing spondylitis and later on in nonradiographic axial spondyloarthritis. This year, EMA has granted golimumab approval for the treatment of active nonradiographic axial spondyloarthritis based on the recently published data from the GO-AHEAD study. This article summarizes recent data on efficacy and safety of golimumab in the treatment of ankylosing spondylitis and nonradiographic axial spondyloarthritis.

  6. Multi-volumetric registration and mosaicking using swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Bozic, Ivan; El-Haddad, Mohamed T.; Malone, Joseph D.; Joos, Karen M.; Patel, Shriji N.; Tao, Yuankai K.

    2017-02-01

    Ophthalmic diagnostic imaging using optical coherence tomography (OCT) is limited by bulk eye motions and a fundamental trade-off between field-of-view (FOV) and sampling density. Here, we introduced a novel multi-volumetric registration and mosaicking method using our previously described multimodal swept-source spectrally encoded scanning laser ophthalmoscopy and OCT (SS-SESLO-OCT) system. Our SS-SESLO-OCT acquires an entire en face fundus SESLO image simultaneously with every OCT cross-section at 200 frames-per-second. In vivo human retinal imaging was performed in a healthy volunteer, and three volumetric datasets were acquired with the volunteer moving freely and refixating between each acquisition. In post-processing, SESLO frames were used to estimate en face rotational and translational motions by registering every frame in all three volumetric datasets to the first frame in the first volume. OCT cross-sections were contrast-normalized and registered axially and rotationally across all volumes. Rotational and translational motions calculated from SESLO frames were applied to corresponding OCT B-scans to compensate for interand intra-B-scan bulk motions, and the three registered volumes were combined into a single interpolated multi-volumetric mosaic. Using complementary information from SESLO and OCT over serially acquired volumes, we demonstrated multivolumetric registration and mosaicking to recover regions of missing data resulting from blinks, saccades, and ocular drifts. We believe our registration method can be directly applied for multi-volumetric motion compensation, averaging, widefield mosaicking, and vascular mapping with potential applications in ophthalmic clinical diagnostics, handheld imaging, and intraoperative guidance.

  7. Imaging Subcellular Dynamics with Fast and Light-Efficient Volumetrically Parallelized Microscopy

    PubMed Central

    Dean, Kevin M.; Roudot, Philippe; Welf, Erik S.; Pohlkamp, Theresa; Garrelts, Gerard; Herz, Joachim; Fiolka, Reto

    2017-01-01

    In fluorescence microscopy, the serial acquisition of 2D images to form a 3D volume limits the maximum imaging speed. This is particularly evident when imaging adherent cells in a light-sheet fluorescence microscopy format, as their elongated morphologies require ~200 image planes per image volume. Here, by illuminating the specimen with three light-sheets, each independently detected, we present a light-efficient, crosstalk free, and volumetrically parallelized 3D microscopy technique that is optimized for high-speed (up to 14 Hz) subcellular (300 nm lateral, 600 nm axial resolution) imaging of adherent cells. We demonstrate 3D imaging of intracellular processes, including cytoskeletal dynamics in single cell migration and collective wound healing for 1500 and 1000 time points, respectively. Further, we capture rapid biological processes, including trafficking of early endosomes with velocities exceeding 10 microns per second and calcium signaling in primary neurons. PMID:28944279

  8. Video-rate volumetric functional imaging of the brain at synaptic resolution

    PubMed Central

    Lu, Rongwen; Sun, Wenzhi; Liang, Yajie; Kerlin, Aaron; Bierfeld, Jens; Seelig, Johannes; Wilson, Daniel E.; Scholl, Benjamin; Mohar, Boaz; Tanimoto, Masashi; Koyama, Minoru; Fitzpatrick, David; Orger, Michael B.; Ji, Na

    2017-01-01

    Neurons and neural networks often extend hundreds to thousands of micrometers in three dimensions. To capture all the calcium transients associated with their activity, we need volume imaging methods with sub-second temporal resolution. Such speed is challenging for conventional two-photon laser scanning microscopy (2PLSM) to achieve, because of its dependence on serial focal scanning in 3D and the limited brightness of indicators. Here we present an optical module that can be easily integrated into standard 2PLSMs to generate an axially elongated Bessel focus. Scanning the Bessel focus in 2D turned frame rate into volume rate and enabled video-rate volumetric imaging. Using Bessel foci designed to maintain lateral resolution that resolves synapses in sparsely labeled brains in vivo, we demonstrated the power of this approach in enabling discoveries for neurobiology by imaging the calcium dynamics of volumes of neurons and synapses in fruit flies, zebrafish larvae, mice, and ferrets in vivo. PMID:28250408

  9. Volumetric Properties of Lithium-Lead Melts

    NASA Astrophysics Data System (ADS)

    Khairulin, R. A.; Abdullaev, R. N.; Stankus, S. V.; Agazhanov, A. S.; Savchenko, I. V.

    2017-02-01

    The density of liquid lithium and lithium-lead alloys (10.02 at.% Pb, 14.98 at.% Pb, 18.06 at.% Pb, 20.02 at.% Pb, 22.24 at.% Pb, 23.09 at.% Pb, 25.10 at.% Pb, 30.15 at.% Pb, 38.21 at.% Pb, 40.11 at.% Pb, 43.08 at.% Pb, 46.65 at.% Pb, 50.15 at.% Pb, 60.23 at.% Pb, 70.01 at.% Pb, 83.00 at.% Pb, and 84.30 at.% Pb) has been measured using the gamma-ray attenuation technique over the temperature range from the liquidus line to 1050 K. The position of the liquidus curve in the Li-Pb phase diagram has been clarified. The compositional dependencies of molar volume and volumetric thermal expansion coefficient of the Li-Pb liquid system have been constructed and discussed.

  10. All Photons Imaging Through Volumetric Scattering

    PubMed Central

    Satat, Guy; Heshmat, Barmak; Raviv, Dan; Raskar, Ramesh

    2016-01-01

    Imaging through thick highly scattering media (sample thickness ≫ mean free path) can realize broad applications in biomedical and industrial imaging as well as remote sensing. Here we propose a computational “All Photons Imaging” (API) framework that utilizes time-resolved measurement for imaging through thick volumetric scattering by using both early arrived (non-scattered) and diffused photons. As opposed to other methods which aim to lock on specific photons (coherent, ballistic, acoustically modulated, etc.), this framework aims to use all of the optical signal. Compared to conventional early photon measurements for imaging through a 15 mm tissue phantom, our method shows a two fold improvement in spatial resolution (4db increase in Peak SNR). This all optical, calibration-free framework enables widefield imaging through thick turbid media, and opens new avenues in non-invasive testing, analysis, and diagnosis. PMID:27683065

  11. Volumetric Geophysical Retrievals in Precipitating Cloud Systems

    NASA Astrophysics Data System (ADS)

    Collis, S. M.; North, K. W.; Jensen, M. P.; Kollias, P.; Williams, C. R.; Bharadwaj, N.; Fridlind, A. M.; Widener, K.; Giangrande, S.

    2011-12-01

    Cloud and climate modeling efforts focused around the Mid-Latitude Continental Convective Clouds Experiment (MC3E) require the retrieval of high quality geophysical parameters pertinent to storm microphysical and dynamical properties. The installation of high resolution polarimetric X- and C-Band scanning radars have greatly enhanced measurements at the Atmospheric Radiation Measurement Southern Great Plain site, however, the volumetric data collected by these sensors is only indirectly related to storm properties. This presentation will outline efforts towards creating a suite of model-like Value Added Products (VAPs) for MC3E derived using existing and new retrieval techniques. Particular focus will be on retrieval of storm dynamics, precipitation microphysics and rainfall accumulations from the scanning radar measurements. Algorithm details and verification efforts will be showcased as well as a timetable for data availability.

  12. All Photons Imaging Through Volumetric Scattering

    NASA Astrophysics Data System (ADS)

    Satat, Guy; Heshmat, Barmak; Raviv, Dan; Raskar, Ramesh

    2016-09-01

    Imaging through thick highly scattering media (sample thickness ≫ mean free path) can realize broad applications in biomedical and industrial imaging as well as remote sensing. Here we propose a computational “All Photons Imaging” (API) framework that utilizes time-resolved measurement for imaging through thick volumetric scattering by using both early arrived (non-scattered) and diffused photons. As opposed to other methods which aim to lock on specific photons (coherent, ballistic, acoustically modulated, etc.), this framework aims to use all of the optical signal. Compared to conventional early photon measurements for imaging through a 15 mm tissue phantom, our method shows a two fold improvement in spatial resolution (4db increase in Peak SNR). This all optical, calibration-free framework enables widefield imaging through thick turbid media, and opens new avenues in non-invasive testing, analysis, and diagnosis.

  13. Twin-Axial Wire Antenna

    DTIC Science & Technology

    2015-08-06

    08-2015 Publication Twin-Axial Wire Antenna David A. Tonn Naval Under Warfare Center Division, Newport 1176 Howell St., Code 00L, Bldg 102T...A An antenna includes a polymer coating having a VLF/LF element and an HF/VHF element embedded therein. A blocking choke is interposed between the...VLF/LF element and the antenna feed t block HF/VHF signals. Small chokes are regularly positioned on the VLF/LF element to eliminate resonances caused

  14. In vivo volumetric imaging of the human corneo-scleral limbus with spectral domain OCT

    PubMed Central

    Bizheva, Kostadinka; Hutchings, Natalie; Sorbara, Luigina; Moayed, Alireza A.; Simpson, Trefford

    2011-01-01

    The limbus is the structurally rich transitional region of tissue between the cornea on one side, and the sclera and conjunctiva on the other. This zone, among other things, contains nerves passing to the cornea, blood and lymph vasculature for oxygen and nutrient delivery and for waste, CO2 removal and drainage of the aqueous humour. In addition, the limbus contains stem cells responsible for the existence and healing of the corneal epithelium. Here we present 3D images of the healthy human limbus, acquired in vivo with a spectral domain optical coherence tomography system operating at 1060nm. Cross-sectional and volumetric images were acquired from temporal and nasal locations in the human limbus with ~3µm x 18µm (axial x lateral) resolution in biological tissue at the rate of 92,000 A-scans/s. The imaging enabled detailed mapping of the corneo-scleral tissue morphology, and visualization of structural details such as the Vogt palisades, the blood and lymph vasculature including the Schlemm’s canal and the trabecular meshwork, as well as corneal nerve fiber bundles. Non-invasive, volumetric, high resolution imaging reveals fine details of the normal human limbal structure, and promises to provide invaluable information about its changes in health and disease as well as during and after corneal surgery. PMID:21750758

  15. Axial Globe Length in Congenital Ptosis.

    PubMed

    Takahashi, Yasuhiro; Kang, Hyera; Kakizaki, Hirohiko

    2015-01-01

    To compare axial globe length between affected and unaffected sides in patients with unilateral congenital ptosis. This prospective observational study included 37 patients (age range: 7 months to 58 years). The axial globe length, margin reflex distance-1 (MRD-1), and refractive power were measured. The axial globe length difference was calculated by subtracting the axial globe length on the unaffected side from that of the affected side. The relationships among axial globe length differences, MRD-1 on the affected sides, and patient ages were analyzed using multiple regression analysis. No significant differences were found in the axial globe length between sides (P = .677). The axial globe length difference was 0.17 ± 0.30 mm (mean ± standard deviation), and two patients (5.4%), aged 32 to 57 years, showed axial globe length more than 0.67 mm longer (corresponding to a refractive power of 2 diopters) on the affected side compared to the unaffected side. The multiple regression model between axial globe length difference, patient age, and MRD-1 on the affected sides was less appropriate (YAGL = 0.003XAGE-0.048XMRD-1 +0.112; r = 0.338; adjusted r2 = 0.062; P = .127). The cylindrical power was greater on the affected side (P = .046), although the spherical power was not different between sides (P = .657). No significant difference was identified in the axial globe length between sides, and only 5% of non-pediatric patients showed an axial globe length more than 0.67 mm longer on the affected side. Congenital ptosis may have little effect on axial globe length elongation, and the risk of axial myopia-induced anisometropic amblyopia may be low in patients with unilateral congenital ptosis. Copyright 2015, SLACK Incorporated.

  16. Extra-Axial Cavernous Hemangioma

    PubMed Central

    Kanaan, Imad; Jallu, Ashraf; Alwatban, Jehad; Patay, Zoltan; Hessler, Richard

    2001-01-01

    Two patients with extra-axial cavernous hemangioma who presented with headache and oculovisual disturbances were investigated with computed tomography and magnetic resonance imaging. The lesions masqueraded as basal meningioma, but this diagnosis was not supported by magnetic resonance spectroscopy in one patient. Cerebral angiography with embolization was indicated in one patient, but embolization was not justified in the other. Both patients underwent a pterional craniotomy. The lesions were extradural and highly vascular, necessitating excessive transfusion in one patient in whom gross total resection was achieved, and precluding satisfactory removal in the other. There was no mortality. Transient ophthalmoplegia, the only complication in one patient, was due to surgical manipulation of the cavernous sinus; it resolved progressively over 3 months. Extra-axial skull base cavernous hemangiomas are distinct entities with clinical and radiological characteristics that differ from those of intraparenchymal cavernous malformations. They can mimic meningiomas or pituitary tumors. In some cases, magnetic resonance spectroscopy may narrow the differential diagnoses. Surgical resection remains the treatment of choice, facilitated by preoperative embolization to reduce intraoperative bleeding and by the application of the principles of skull base surgery. Fractionated radiotherapy is an alternative in partial or difficult resections and in high-risk and elderly patients. ImagesFigure 1Figure 2Figure 3Figure 4 PMID:17167631

  17. PWR AXIAL BURNUP PROFILE ANALYSIS

    SciTech Connect

    J.M. Acaglione

    2003-09-17

    The purpose of this activity is to develop a representative ''limiting'' axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the ''end-effect''. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package. The scope of this calculation covers an initial enrichment range of 3.0 through 5.0 wt% U-235 and a burnup range of 10 through 50 GWd/MTU. This activity supports the validation of the process for ensuring conservative generation of spent fuel isotopics with respect to criticality safety applications, and the use of burnup credit for commercial spent nuclear fuel. The intended use of these results will be in the development of PWR waste package loading curves, and applications involving burnup credit. Limitations of this evaluation are that the limiting profiles are only confirmed for use with the B&W 15 x 15 fuel assembly design. However, this assembly design is considered bounding of all other typical commercial PWR fuel assembly designs. This calculation is subject to the Quality Assurance Requirements and Description (QARD) because this activity supports investigations of items or barriers on the Q-list (YMP 2001).

  18. Use of 320-detector computed tomographic angiography for infants and young children with congenital heart disease.

    PubMed

    Al-Mousily, Faris; Shifrin, Roger Y; Fricker, Frederick J; Feranec, Nicholas; Quinn, Nancy S; Chandran, Arun

    2011-04-01

    Pediatric patients with complex congenital heart disease (CHD) face a lifetime of treatment with interventional therapeutic and palliative procedures. Echocardiography remains the mainstay for noninvasive imaging of congenital heart lesions. This often is supplemented with diagnostic cardiac catheterization for additional anatomic and physiologic characterization. However, recent technological improvements in computed tomography (CT) and magnetic resonance imaging (MRI) have led to an increased focus on the use of these techniques given their better safety profile. This study aimed to review the authors' experience with a 320-slice multidetector CT scanner in the evaluation of CHD in children. This retrospective case study investigated 22 infants and young children with a provisional diagnosis of CHD. Their anatomic evaluation was performed using a 320-slice Aquilon ONE CT scanner. Of these 22 patients, 14 were examined without cardiac gating. This was subsequently modified to a prospective gated, targeted protocol to decrease the radiation dose. The images were interpreted by an experienced radiologist and a pediatric cardiologist. Continuous variables were expressed as mean and standard deviation or range, and the two imaging protocols were compared. A comparison of exposure rates with those from other pediatric studies that had used the 64-slice CT angiography also was performed. For the first group of patients, with nongated CT examinations, the mean effective whole-body radiation dose was 1.8 ± 0.71 millisieverts (mSv) (range, 0.96-3.2 mSv). For the second group, the mean was 0.8 ± 0.39 mSv (range, 0.4-1.5 mSv). Although the radiation dose was reduced dramatically, clinicians must be vigilant about the cumulative risk of radiation exposure.

  19. Influence of constraints on axial growth reduction of cylindrical Li-ion battery electrode particles

    NASA Astrophysics Data System (ADS)

    Chakraborty, Jeevanjyoti; Please, Colin P.; Goriely, Alain; Chapman, S. Jonathan

    2015-04-01

    Volumetric expansion of silicon anode particles in a lithium-ion battery during charging may lead to the generation of undesirable internal stresses. For a cylindrical particle such growth may also lead to failure by buckling if the expansion is constrained in the axial direction due to other particles or supporting structures. To mitigate this problem, the possibility of reducing axial growth is investigated theoretically by studying simple modifications of the solid cylinder geometry. First, an annular cylinder is considered with lithiation either from the inside or from the outside. In both cases, the reduction of axial growth is not found to be significant. Next, explicit physical constraints are studied by addition of a non-growing elasto-plastic material: first, an outer annular constraint on a solid silicon cylinder, and second a rod-like inner constraint for an annular silicon cylinder. In both cases, it is found that axial growth can be reduced if the yield stress of the constraining material is significantly higher than that of silicon and/or the thickness of the constraint is relatively high. Phase diagrams are presented for both the outer and the inner constraint cases to identify desirable operating zones. Finally, to interpret the phase diagrams and isolate the key physical principles two different simplified models are presented and are shown to recover important qualitative trends of the numerical simulation results.

  20. Axial vector Z‧ and anomaly cancellation

    NASA Astrophysics Data System (ADS)

    Ismail, Ahmed; Keung, Wai-Yee; Tsao, Kuo-Hsing; Unwin, James

    2017-05-01

    Whilst the prospect of new Z‧ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that in a large class of models masses of these new states are expected to be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.

  1. System Study for Axial Vane Engine Technology

    NASA Technical Reports Server (NTRS)

    Badley, Patrick R.; Smith, Michael R.; Gould, Cedric O.

    2008-01-01

    The purpose of this engine feasibility study was to determine the benefits that can be achieved by incorporating positive displacement axial vane compression and expansion stages into high bypass turbofan engines. These positive-displacement stages would replace some or all of the conventional compressor and turbine stages in the turbine engine, but not the fan. The study considered combustion occurring internal to an axial vane component (i.e., Diesel engine replacing the standard turbine engine combustor, burner, and turbine); and external continuous flow combustion with an axial vane compressor and an axial vane turbine replacing conventional compressor and turbine systems.

  2. Resolution of axial shear strain elastography

    NASA Astrophysics Data System (ADS)

    Thitaikumar, Arun; Righetti, Raffaella; Krouskop, Thomas A.; Ophir, Jonathan

    2006-10-01

    The technique of mapping the local axial component of the shear strain due to quasi-static axial compression is defined as axial shear strain elastography. In this paper, the spatial resolution of axial shear strain elastography is investigated through simulations, using an elastically stiff cylindrical lesion embedded in a homogeneously softer background. Resolution was defined as the smallest size of the inclusion for which the strain value at the inclusion/background interface was greater than the average of the axial shear strain values at the interface and inside the inclusion. The resolution was measured from the axial shear strain profile oriented at 45° to the axis of beam propagation, due to the absence of axial shear strain along the normal directions. The effects of the ultrasound system parameters such as bandwidth, beamwidth and transducer element pitch along with signal processing parameters such as correlation window length (W) and axial shift (ΔW) on the estimated resolution were investigated. The results show that the resolution (at 45° orientation) is determined by the bandwidth and the beamwidth. However, the upper bound on the resolution is limited by the larger of the beamwidth and the window length, which is scaled inversely to the bandwidth. The results also show that the resolution is proportional to the pitch and not significantly affected by the axial window shift.

  3. Axial cylinder internal combustion engine

    SciTech Connect

    Gonzalez, C.

    1992-03-10

    This patent describes improvement in a barrel type internal combustion engine including an engine block having axial-positioned cylinders with reciprocating pistons arranged in a circular pattern: a drive shaft concentrically positioned within the cylinder block having an offset portion extending outside the cylinder block; a wobble spider rotatably journaled to the offset portion; connecting rods for each cylinder connecting each piston to the wobble spider. The improvement comprising: a first sleeve bearing means supporting the drive shaft in the engine block in a cantilevered manner for radial loads; a second sleeve bearing means rotatably supporting the wobble spider on the offset portion of the drive shaft for radial loads; a first roller bearing means positioned between the offset portion of the drive shaft and the wobble spider carrying thrust loadings only; a second roller bearing means carrying thrust loads only reacting to the first roller bearing located on the opposite end of the driveshaft between the shaft and the engine block.

  4. Axially grooved heat pipe study

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A technology evaluation study on axially grooved heat pipes is presented. The state-of-the-art is reviewed and present and future requirements are identified. Analytical models, the Groove Analysis Program (GAP) and a closed form solution, were developed to facilitate parametric performance evaluations. GAP provides a numerical solution of the differential equations which govern the hydrodynamic flow. The model accounts for liquid recession, liquid/vapor shear interaction, puddle flow as well as laminar and turbulent vapor flow conditions. The closed form solution was developed to reduce computation time and complexity in parametric evaluations. It is applicable to laminar and ideal charge conditions, liquid/vapor shear interaction, and an empirical liquid flow factor which accounts for groove geometry and liquid recession effects. The validity of the closed form solution is verified by comparison with GAP predictions and measured data.

  5. Unsteady Flows in Axial Turbomachines

    NASA Technical Reports Server (NTRS)

    Marble, F. E.; Rannie, W. D.

    1957-01-01

    Of the various unsteady flows that occur in axial turbomachines certain asymmetric disturbances, of wave length large in comparison with blade spacing, have become understood to a certain extent. These disturbances divide themselves into two categories: self-induced oscillations and force disturbances. A special type of propagating stall appears as a self-induced disturbance; an asymmetric velocity profile introduced at the compressor inlet constitutes a forced disturbance. Both phenomena have been treated from a unified theoretical point of view in which the asymmetric disturbances are linearized and the blade characteristics are assumed quasi-steady. Experimental results are in essential agreement with this theory wherever the limitations of the theory are satisfied. For the self-induced disturbances and the more interesting examples of the forced disturbances, the dominant blade characteristic is the dependence of total pressure loss, rather than the turning angle, upon the local blade inlet angle.

  6. WE-G-BRF-04: Robust Real-Time Volumetric Imaging Based On One Single Projection

    SciTech Connect

    Xu, Y; Yan, H; Ouyang, L; Wang, J; Jiang, S; Jia, X; Zhou, L

    2014-06-15

    Purpose: Real-time volumetric imaging is highly desirable to provide instantaneous image guidance for lung radiation therapy. This study proposes a scheme to achieve this goal using one single projection by utilizing sparse learning and a principal component analysis (PCA) based lung motion model. Methods: A patient-specific PCA-based lung motion model is first constructed by analyzing deformable vector fields (DVFs) between a reference image and 4DCT images at each phase. At the training stage, we “learn” the relationship between the DVFs and the projection using sparse learning. Specifically, we first partition the projections into patches, and then apply sparse learning to automatically identify patches that best correlate with the principal components of the DVFs. Once the relationship is established, at the application stage, we first employ a patchbased intensity correction method to overcome the problem of different intensity scale between the calculated projection in the training stage and the measured projection in the application stage. The corrected projection image is then fed to the trained model to derive a DVF, which is applied to the reference image, yielding a volumetric image corresponding to the projection. We have validated our method through a NCAT phantom simulation case and one experiment case. Results: Sparse learning can automatically select those patches containing motion information, such as those around diaphragm. For the simulation case, over 98% of the lung region pass the generalized gamma test (10HU/1mm), indicating combined accuracy in both intensity and spatial domain. For the experimental case, the average tumor localization errors projected to the imager are 0.68 mm and 0.4 mm on the axial and tangential direction, respectively. Conclusion: The proposed method is capable of accurately generating a volumetric image using one single projection. It will potentially offer real-time volumetric image guidance to facilitate lung

  7. Regional Volumetric Change of the Tongue during Mastication in Pigs

    PubMed Central

    LIU, Z. J.; YAMAMURA, B.; SHCHERBATYY, V.; GREEN, J. R.

    2007-01-01

    SUMMARY Structure and movement of the tongue have been studied extensively, but little has been done on its 3D deformation and ensuing volumetric changes during various functions. The purpose of this study is to investigate the volumetric changes of a regional section of the tongue during feeding. Four 12-week-old Yucatan miniature pigs were used. During natural mastication and water drinking, the width, length, thickness, and volumetric changes were measured using six implanted ultrasonic crystals, which circumscribed a wedge-shaped volume in the region of the tongue body. Jaw movements were videotaped and digitized. Signals from these two sources were synchronized to allow real-time analyses. Significant volumetric changes (p<0.001) were found in chewing, ingestion and drinking, and these changes were stereotypical in relation to rhythmic jaw movements. Volumetric change during chewing was not only more regular, but significantly larger (45.6%, p < 0.001) than that during ingestion (31.4%). The volumetric changes were less regular in drinking and the changing range (30.4%) was close to that during ingestion. Real-time analysis indicated that the volume began increasing at late jaw closing and reached the peak at late power stroke. The duration of volume increase only took up 33.4% of the total chewing cycle length, significantly shorter than that of volume decrease. Correlation analysis revealed that the change in posterior dorsal and ventral widths had the greatest positive association with volumetric change (r = 0.43) in direction. The covariance calculations further indicated that dimensional changes in length and thickness coupled negatively with volumetric changes in amplitude. These results revealed that regional volumetric change of the tongue occurs during feeding, and chewing requires larger volumetric changes than do ingestion and drinking. Volumetric expansion occurs in the phase of power stroke during chewing and is coupled with increases of widths in

  8. Parkinson's disease: diagnostic utility of volumetric imaging.

    PubMed

    Lin, Wei-Che; Chou, Kun-Hsien; Lee, Pei-Lin; Tsai, Nai-Wen; Chen, Hsiu-Ling; Hsu, Ai-Ling; Chen, Meng-Hsiang; Huang, Yung-Cheng; Lin, Ching-Po; Lu, Cheng-Hsien

    2017-04-01

    This paper aims to examine the effectiveness of structural imaging as an aid in the diagnosis of Parkinson's disease (PD). High-resolution T 1-weighted magnetic resonance imaging was performed in 72 patients with idiopathic PD (mean age, 61.08 years) and 73 healthy subjects (mean age, 58.96 years). The whole brain was parcellated into 95 regions of interest using composite anatomical atlases, and region volumes were calculated. Three diagnostic classifiers were constructed using binary multiple logistic regression modeling: the (i) basal ganglion prior classifier, (ii) data-driven classifier, and (iii) basal ganglion prior/data-driven hybrid classifier. Leave-one-out cross validation was used to unbiasedly evaluate the predictive accuracy of imaging features. Pearson's correlation analysis was further performed to correlate outcome measurement using the best PD classifier with disease severity. Smaller volume in susceptible regions is diagnostic for Parkinson's disease. Compared with the other two classifiers, the basal ganglion prior/data-driven hybrid classifier had the highest diagnostic reliability with a sensitivity of 74%, specificity of 75%, and accuracy of 74%. Furthermore, outcome measurement using this classifier was associated with disease severity. Brain structural volumetric analysis with multiple logistic regression modeling can be a complementary tool for diagnosing PD.

  9. A hand-held immaterial volumetric display

    NASA Astrophysics Data System (ADS)

    Sand, Antti; Rakkolainen, Ismo

    2014-03-01

    We have created an ultralight, movable, "immaterial" fogscreen. It is based on the fogscreen mid-air imaging technology. The hand-held unit is roughly the size and weight of an ordinary toaster. If the screen is tracked, it can be swept in the air to create mid-air slices of volumetric objects, or to show augmented reality (AR) content on top of real objects. Interfacing devices and methodologies, such as hand and gesture trackers, camera-based trackers and object recognition, can make the screen interactive. The user can easily interact with any physical object or virtual information, as the screen is permeable. Any real objects can be seen through the screen, instead of e.g., through a video-based augmented reality screen. It creates a mixed reality setup where both the real world object and the augmented reality content can be viewed and interacted with simultaneously. The hand-held mid-air screen can be used e.g., as a novel collaborating or classroom tool for individual students or small groups.

  10. Volumetric Optoacoustic Temperature Mapping in Photothermal Therapy.

    PubMed

    Landa, Francisco Javier Oyaga; Deán-Ben, Xosé Luís; Sroka, Ronald; Razansky, Daniel

    2017-08-29

    Photothermal therapy and ablation are commonplace medical procedures employed for treatment of tumors, vascular and brain abnormalities as well as other disorders that require selective destruction of tissues. Yet, accurate mapping of the dynamic temperature field distribution in the treated region represents an unmet clinical need, strongly affecting the clinical outcome of these interventions. We introduce a fast three-dimensional temperature mapping method based on real-time optoacoustic sensing of the treated region coupled with a thermal-diffusion-based model of heat distribution in tissues. Deviations of the optoacoustic temperature readings provided at 40  ms intervals remained below 10% in tissue-mimicking phantom experiments for temperature elevations above 3 °C, as validated by simultaneous thermocouple measurements. Performance of the new method to dynamically estimate the volumetric temperature distribution was further showcased in post-mortem mouse imaging experiments. The newly discovered capacity to non-invasively measure the temperature map in an entire treated volume with both high spatial and temporal resolutions holds potential for improving safety and efficacy of light-based therapeutic interventions.

  11. Liquid rocket engine axial-flow turbopumps

    NASA Technical Reports Server (NTRS)

    Scheer, D. D.; Huppert, M. C.; Viteri, F.; Farquhar, J.; Keller, R. B., Jr. (Editor)

    1978-01-01

    The axial pump is considered in terms of the total turbopump assembly. Stage hydrodynamic design, pump rotor assembly, pump materials for liquid hydrogen applications, and safety factors as utilized in state of the art pumps are among the topics discussed. Axial pump applications are included.

  12. Quantification of volumetric cerebral blood flow using hybrid laser speckle contract and optical coherence tomography (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Valim, Niksa; Dunn, Andrew K.

    2016-03-01

    Studying neurovascular blood flow function in cerebrovascular activities requires accurate visualization and characterization of blood flow volume as well as the dynamics of blood cells in microcirculation. In this study, we present a novel integration of laser speckle contrast imaging (LSCI) and spectral domain optical coherence tomography (SD-OCT) for rapid volumetric imaging of blood flow in cortical capillaries. LSCI uses the illumination of wide-field near infrared light (NIR) and monitors back scattered light to characterize the relative dynamics of blood flow in microcirculation. Absolute measurement of blood cells and blood volume requires high-resolution volumetric structural information. SD-OCT system uses coherence gating to measure scattered light from a small volume within high structural resolution. The structural imaging system rapidly assesses large number of capillaries for spatio-temporal tracking of red blood cells (RBC). A very fast-ultra resolution SD-OCT system was developed for imaging high-resolution volumetric samples. The system employed an ultra wideband light source (1310 ± 200 nm in wavelength) corresponding to an axial resolution of 3 micrometers in tissue. The spectrometer of the SD-OCT was customized for a maximum scanning rate of 147,000 line/s. We demonstrated a fast volumetric OCT angiography algorithm to visualize large numbers of vessels in a 2-mm deep sample volume. A LSCI system that has been developed previously in our group was integrated to the imaging system for the characterization of dynamic blood cells. The conjunction data from LSCI and SD-OCT systems imply the feasibility of accurate quantification of absolute cortical blood flow.

  13. Hyperspectral image classification based on volumetric texture and dimensionality reduction

    NASA Astrophysics Data System (ADS)

    Su, Hongjun; Sheng, Yehua; Du, Peijun; Chen, Chen; Liu, Kui

    2015-06-01

    A novel approach using volumetric texture and reduced-spectral features is presented for hyperspectral image classification. Using this approach, the volumetric textural features were extracted by volumetric gray-level co-occurrence matrices (VGLCM). The spectral features were extracted by minimum estimated abundance covariance (MEAC) and linear prediction (LP)-based band selection, and a semi-supervised k-means (SKM) clustering method with deleting the worst cluster (SKMd) bandclustering algorithms. Moreover, four feature combination schemes were designed for hyperspectral image classification by using spectral and textural features. It has been proven that the proposed method using VGLCM outperforms the gray-level co-occurrence matrices (GLCM) method, and the experimental results indicate that the combination of spectral information with volumetric textural features leads to an improved classification performance in hyperspectral imagery.

  14. Using Kriging to Interpolate Spatially Distributed Volumetric Medical Data

    DTIC Science & Technology

    1996-12-01

    Routine cases in diagnostic radiology require the interpolation of volumetric medical imaging data sets. Inaccurate renditions of interpolated...patient space. Kriging is investigated in this research to interpolate medical imaging volumes. Kriging requires data to be spatially distributed

  15. Volumetric expansion of gutta-percha in contact with eugenol.

    PubMed

    Michaud, Rick A; Burgess, John; Barfield, Robert D; Cakir, Deniz; McNeal, Sandre F; Eleazer, Paul D

    2008-12-01

    The aim of this study was to compare the volumetric expansion of gutta-percha in the presence of eugenol or physiologic saline over time. Sections of gutta-percha cones were scanned to determine their total volume and surface area. They were then placed in sealed test tubes with either 2 microL eugenol or 2 microL saline and allowed to soak for 24 hours, 7 days, or 30 days. The results were scanned again to determine the volumetric changes in the material after placement in the test solutions. The results were statistically analyzed by using t tests and analysis of variance. Specimens soaked in eugenol showed a dramatic increase in volumetric expansion versus the saline group at all time periods. Sealers that incorporate eugenol could be attributed to gutta-percha volumetric expansion over time, thereby creating a better seal of the obturation material.

  16. Axial interaction free-electron laser

    DOEpatents

    Carlsten, B.E.

    1997-09-02

    Electron orbits from a helical axial wiggler in an axial guide field are absolutely unstable as power is extracted from the particles. For off-axis beams an axial FEL mechanism exists when the axial electric field in a TM mode is wiggled to interact with the axial velocity of the electrons that form the beam. The interaction strength is comparable to that for helical FELs and is insensitive to beam orbit errors. The orbits for this mechanism are extremely stable in the absence of space charge and lead to high extraction efficiencies without particle phasing incoherence or interception. This interaction mechanism is suitable for use with intense annular electron beams for high power generation at microwave frequencies. 5 figs.

  17. Axial interaction free-electron laser

    DOEpatents

    Carlsten, Bruce E.

    1997-01-01

    Electron orbits from a helical axial wiggler in an axial guide field are absolutely unstable as power is extracted from the particles. For off-axis beams an axial FEL mechanism exists when the axial electric field in a TM mode is wiggled to interact with the axial velocity of the electrons that form the beam. The interaction strength is comparable to that for helical FELs and is insensitive to beam orbit errors. The orbits for this mechanism are extremely stable in the absence of space charge and lead to high extraction efficiencies without particle phasing incoherence or interception. This interaction mechanism is suitable for use with intense annular electron beams for high power generation at microwave frequencies.

  18. Increasing the volumetric efficiency of Diesel engines by intake pipes

    NASA Technical Reports Server (NTRS)

    List, Hans

    1933-01-01

    Development of a method for calculating the volumetric efficiency of piston engines with intake pipes. Application of this method to the scavenging pumps of two-stroke-cycle engines with crankcase scavenging and to four-stroke-cycle engines. The utility of the method is demonstrated by volumetric-efficiency tests of the two-stroke-cycle engines with crankcase scavenging. Its practical application to the calculation of intake pipes is illustrated by example.

  19. Novel Integration Radial and Axial Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Blumenstock, Kenneth; Brown, Gary

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

  20. Novel Integrated Radial and Axial Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Blumenstock, Kenneth A.; Brown, Gary L.; Powers, Edward I. (Technical Monitor)

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.

  1. Volumetric optoacoustic monitoring of endovenous laser treatments

    NASA Astrophysics Data System (ADS)

    Fehm, Thomas F.; Deán-Ben, Xosé L.; Schaur, Peter; Sroka, Ronald; Razansky, Daniel

    2016-03-01

    Chronic venous insufficiency (CVI) is one of the most common medical conditions with reported prevalence estimates as high as 30% in the adult population. Although conservative management with compression therapy may improve the symptoms associated with CVI, healing often demands invasive procedures. Besides established surgical methods like vein stripping or bypassing, endovenous laser therapy (ELT) emerged as a promising novel treatment option during the last 15 years offering multiple advantages such as less pain and faster recovery. Much of the treatment success hereby depends on monitoring of the treatment progression using clinical imaging modalities such as Doppler ultrasound. The latter however do not provide sufficient contrast, spatial resolution and three-dimensional imaging capacity which is necessary for accurate online lesion assessment during treatment. As a consequence, incidence of recanalization, lack of vessel occlusion and collateral damage remains highly variable among patients. In this study, we examined the capacity of volumetric optoacoustic tomography (VOT) for real-time monitoring of ELT using an ex-vivo ox foot model. ELT was performed on subcutaneous veins while optoacoustic signals were acquired and reconstructed in real-time and at a spatial resolution in the order of 200μm. VOT images showed spatio-temporal maps of the lesion progression, characteristics of the vessel wall, and position of the ablation fiber's tip during the pull back. It was also possible to correlate the images with the temperature elevation measured in the area adjacent to the ablation spot. We conclude that VOT is a promising tool for providing online feedback during endovenous laser therapy.

  2. Dual-Gated Volumetric Modulated Arc Therapy.

    PubMed

    Fahimian, Benjamin; Wu, Junqing; Wu, Huanmei; Geneser, Sarah; Xing, Lei

    2014-09-25

    Gated Volumetric Modulated Arc Therapy (VMAT) is an emerging radiation therapy modality for treatment of tumors affected by respiratory motion. However, gating significantly prolongs the treatment time, as delivery is only activated during a single respiratory phase. To enhance the efficiency of gated VMAT delivery, a novel dual-gated VMAT (DG-VMAT) technique, in which delivery is executed at both exhale and inhale phases in a given arc rotation, is developed and experimentally evaluated. Arc delivery at two phases is realized by sequentially interleaving control points consisting of MUs, MLC sequences, and angles of VMAT plans generated at the exhale and inhale phases. Dual-gated delivery is initiated when a respiration gating signal enters the exhale window; when the exhale delivery concludes, the beam turns off and the gantry rolls back to the starting position for the inhale window. The process is then repeated until both inhale and exhale arcs are fully delivered. DG-VMAT plan delivery accuracy was assessed using a pinpoint chamber and diode array phantom undergoing programmed motion. DG-VMAT delivery was experimentally implemented through custom XML scripting in Varian's TrueBeam™ STx Developer Mode. Relative to single gated delivery at exhale, the treatment time was improved by 95.5% for a sinusoidal breathing pattern. The pinpoint chamber dose measurement agreed with the calculated dose within 0.7%. For the DG-VMAT delivery, 97.5% of the diode array measurements passed the 3%/3 mm gamma criterion. The feasibility of DG-VMAT delivery scheme has been experimentally demonstrated for the first time. By leveraging the stability and natural pauses that occur at end-inspiration and end-exhalation, DG-VMAT provides a practical method for enhancing gated delivery efficiency by up to a factor of two.

  3. Subcortical volumetric abnormalities in bipolar disorder

    PubMed Central

    Hibar, D P; Westlye, L T; van Erp, T G M; Rasmussen, J; Leonardo, C D; Faskowitz, J; Haukvik, U K; Hartberg, C B; Doan, N T; Agartz, I; Dale, A M; Gruber, O; Krämer, B; Trost, S; Liberg, B; Abé, C; Ekman, C J; Ingvar, M; Landén, M; Fears, S C; Freimer, N B; Bearden, C E; Sprooten, E; Glahn, D C; Pearlson, G D; Emsell, L; Kenney, J; Scanlon, C; McDonald, C; Cannon, D M; Almeida, J; Versace, A; Caseras, X; Lawrence, N S; Phillips, M L; Dima, D; Delvecchio, G; Frangou, S; Satterthwaite, T D; Wolf, D; Houenou, J; Henry, C; Malt, U F; Bøen, E; Elvsåshagen, T; Young, A H; Lloyd, A J; Goodwin, G M; Mackay, C E; Bourne, C; Bilderbeck, A; Abramovic, L; Boks, M P; van Haren, N E M; Ophoff, R A; Kahn, R S; Bauer, M; Pfennig, A; Alda, M; Hajek, T; Mwangi, B; Soares, J C; Nickson, T; Dimitrova, R; Sussmann, J E; Hagenaars, S; Whalley, H C; McIntosh, A M; Thompson, P M; Andreassen, O A

    2016-01-01

    Considerable uncertainty exists about the defining brain changes associated with bipolar disorder (BD). Understanding and quantifying the sources of uncertainty can help generate novel clinical hypotheses about etiology and assist in the development of biomarkers for indexing disease progression and prognosis. Here we were interested in quantifying case–control differences in intracranial volume (ICV) and each of eight subcortical brain measures: nucleus accumbens, amygdala, caudate, hippocampus, globus pallidus, putamen, thalamus, lateral ventricles. In a large study of 1710 BD patients and 2594 healthy controls, we found consistent volumetric reductions in BD patients for mean hippocampus (Cohen's d=−0.232; P=3.50 × 10−7) and thalamus (d=−0.148; P=4.27 × 10−3) and enlarged lateral ventricles (d=−0.260; P=3.93 × 10−5) in patients. No significant effect of age at illness onset was detected. Stratifying patients based on clinical subtype (BD type I or type II) revealed that BDI patients had significantly larger lateral ventricles and smaller hippocampus and amygdala than controls. However, when comparing BDI and BDII patients directly, we did not detect any significant differences in brain volume. This likely represents similar etiology between BD subtype classifications. Exploratory analyses revealed significantly larger thalamic volumes in patients taking lithium compared with patients not taking lithium. We detected no significant differences between BDII patients and controls in the largest such comparison to date. Findings in this study should be interpreted with caution and with careful consideration of the limitations inherent to meta-analyzed neuroimaging comparisons. PMID:26857596

  4. Real-time volumetric scintillation dosimetry

    NASA Astrophysics Data System (ADS)

    Beddar, S.

    2015-01-01

    The goal of this brief review is to review the current status of real-time 3D scintillation dosimetry and what has been done so far in this area. The basic concept is to use a large volume of a scintillator material (liquid or solid) to measure or image the dose distributions from external radiation therapy (RT) beams in three dimensions. In this configuration, the scintillator material fulfills the dual role of being the detector and the phantom material in which the measurements are being performed. In this case, dose perturbations caused by the introduction of a detector within a phantom will not be at issue. All the detector configurations that have been conceived to date used a Charge-Coupled Device (CCD) camera to measure the light produced within the scintillator. In order to accurately measure the scintillation light, one must correct for various optical artefacts that arise as the light propagates from the scintillating centers through the optical chain to the CCD chip. Quenching, defined in its simplest form as a nonlinear response to high-linear energy transfer (LET) charged particles, is one of the disadvantages when such systems are used to measure the absorbed dose from high-LET particles such protons. However, correction methods that restore the linear dose response through the whole proton range have been proven to be effective for both liquid and plastic scintillators. Volumetric scintillation dosimetry has the potential to provide fast, high-resolution and accurate 3D imaging of RT dose distributions. Further research is warranted to optimize the necessary image reconstruction methods and optical corrections needed to achieve its full potential.

  5. Subcortical volumetric abnormalities in bipolar disorder.

    PubMed

    Hibar, D P; Westlye, L T; van Erp, T G M; Rasmussen, J; Leonardo, C D; Faskowitz, J; Haukvik, U K; Hartberg, C B; Doan, N T; Agartz, I; Dale, A M; Gruber, O; Krämer, B; Trost, S; Liberg, B; Abé, C; Ekman, C J; Ingvar, M; Landén, M; Fears, S C; Freimer, N B; Bearden, C E; Sprooten, E; Glahn, D C; Pearlson, G D; Emsell, L; Kenney, J; Scanlon, C; McDonald, C; Cannon, D M; Almeida, J; Versace, A; Caseras, X; Lawrence, N S; Phillips, M L; Dima, D; Delvecchio, G; Frangou, S; Satterthwaite, T D; Wolf, D; Houenou, J; Henry, C; Malt, U F; Bøen, E; Elvsåshagen, T; Young, A H; Lloyd, A J; Goodwin, G M; Mackay, C E; Bourne, C; Bilderbeck, A; Abramovic, L; Boks, M P; van Haren, N E M; Ophoff, R A; Kahn, R S; Bauer, M; Pfennig, A; Alda, M; Hajek, T; Mwangi, B; Soares, J C; Nickson, T; Dimitrova, R; Sussmann, J E; Hagenaars, S; Whalley, H C; McIntosh, A M; Thompson, P M; Andreassen, O A

    2016-12-01

    Considerable uncertainty exists about the defining brain changes associated with bipolar disorder (BD). Understanding and quantifying the sources of uncertainty can help generate novel clinical hypotheses about etiology and assist in the development of biomarkers for indexing disease progression and prognosis. Here we were interested in quantifying case-control differences in intracranial volume (ICV) and each of eight subcortical brain measures: nucleus accumbens, amygdala, caudate, hippocampus, globus pallidus, putamen, thalamus, lateral ventricles. In a large study of 1710 BD patients and 2594 healthy controls, we found consistent volumetric reductions in BD patients for mean hippocampus (Cohen's d=-0.232; P=3.50 × 10(-7)) and thalamus (d=-0.148; P=4.27 × 10(-3)) and enlarged lateral ventricles (d=-0.260; P=3.93 × 10(-5)) in patients. No significant effect of age at illness onset was detected. Stratifying patients based on clinical subtype (BD type I or type II) revealed that BDI patients had significantly larger lateral ventricles and smaller hippocampus and amygdala than controls. However, when comparing BDI and BDII patients directly, we did not detect any significant differences in brain volume. This likely represents similar etiology between BD subtype classifications. Exploratory analyses revealed significantly larger thalamic volumes in patients taking lithium compared with patients not taking lithium. We detected no significant differences between BDII patients and controls in the largest such comparison to date. Findings in this study should be interpreted with caution and with careful consideration of the limitations inherent to meta-analyzed neuroimaging comparisons.

  6. Volumetric Modulated Arc Radiotherapy for Vestibular Schwannomas

    SciTech Connect

    Lagerwaard, Frank J. Meijer, Otto W.M.; Hoorn, Elles A.P. van der; Verbakel, Wilko; Slotman, Ben J.; Senan, Suresh

    2009-06-01

    Purpose: To evaluate volumetric modulated arc radiotherapy (RapidArc [RA]), a novel approach allowing for rapid treatment delivery, for the treatment of vestibular schwannoma (VS). Methods and Materials: The RA plans were generated for a small (0.5 cm{sup 3}), intermediate (2.8 cm{sup 3}), and large (14.8 cm{sup 3}) VS. The prescription dose was 12.5 Gy to the encompassing 80% isodose. The RA plans were compared with conventional radiosurgery plans using both a single dynamic conformal arc (1DCA) and five noncoplanar dynamic conformal arcs (5DCA). Conformity indices (CI) and dose-volume histograms of critical organs were compared. The RA plan for the medium-sized VS was measured in a phantom using Gafchromic EBT films and compared with calculated dose distributions. Results: The RA planning was completed within 30 min in all cases, and calculated treatment delivery time (after patient setup) was 5 min vs. 20 min for 5DCA. A superior CI was achieved with RA, with a substantial decrease in low-dose irradiation of the normal brain achieved relative to 5DCA plans. Maximum doses to critical organs were similar for RA and 5DCA but were higher for 1DCA. Film measurements showed the differences between calculated and measured doses to be smaller than 1.5% in the high-dose area and smaller than 3% in the low-dose area. Conclusion: The RA plans consistently achieved a higher CI and decrease in areas of low-dose irradiation. This, together with shorter treatment delivery times, has led to RA replacing our conventional five-arc radiosurgery technique for VS.

  7. Soft bilateral filtering volumetric shadows using cube shadow maps

    PubMed Central

    Ali, Hatam H.; Sunar, Mohd Shahrizal; Kolivand, Hoshang

    2017-01-01

    Volumetric shadows often increase the realism of rendered scenes in computer graphics. Typical volumetric shadows techniques do not provide a smooth transition effect in real-time with conservation on crispness of boundaries. This research presents a new technique for generating high quality volumetric shadows by sampling and interpolation. Contrary to conventional ray marching method, which requires extensive time, this proposed technique adopts downsampling in calculating ray marching. Furthermore, light scattering is computed in High Dynamic Range buffer to generate tone mapping. The bilateral interpolation is used along a view rays to smooth transition of volumetric shadows with respect to preserving-edges. In addition, this technique applied a cube shadow map to create multiple shadows. The contribution of this technique isreducing the number of sample points in evaluating light scattering and then introducing bilateral interpolation to improve volumetric shadows. This contribution is done by removing the inherent deficiencies significantly in shadow maps. This technique allows obtaining soft marvelous volumetric shadows, having a good performance and high quality, which show its potential for interactive applications. PMID:28632740

  8. Visualization and volumetric structures from MR images of the brain

    SciTech Connect

    Parvin, B.; Johnston, W.; Robertson, D.

    1994-03-01

    Pinta is a system for segmentation and visualization of anatomical structures obtained from serial sections reconstructed from magnetic resonance imaging. The system approaches the segmentation problem by assigning each volumetric region to an anatomical structure. This is accomplished by satisfying constraints at the pixel level, slice level, and volumetric level. Each slice is represented by an attributed graph, where nodes correspond to regions and links correspond to the relations between regions. These regions are obtained by grouping pixels based on similarity and proximity. The slice level attributed graphs are then coerced to form a volumetric attributed graph, where volumetric consistency can be verified. The main novelty of our approach is in the use of the volumetric graph to ensure consistency from symbolic representations obtained from individual slices. In this fashion, the system allows errors to be made at the slice level, yet removes them when the volumetric consistency cannot be verified. Once the segmentation is complete, the 3D surfaces of the brain can be constructed and visualized.

  9. Non-Radiographic Axial Spondyloarthritis.

    PubMed

    Slobodin, Gleb; Eshed, Iris

    2015-12-01

    The term non-radiographic axial spondyloarthritis (nrAxSpA) was coined for patients who have a clinical picture of ankylosing spondylitis (AS) but do not exhibit radiographic sacroiliitis. The ASAS classification criteria for nrAxSpA, ensuring the recruitment of homogenous study cohorts, were accepted in 2009, although the respective diagnostic criteria for daily clinical practice have not yet been developed. The clinical diagnosis should be based on the composite of clinical symptoms and signs of the disease, HLA B27 status, and magnetic resonance imaging (MRI) of sacroiliac joints. Notably, a negative MRI or HLA B27 does not exclude the diagnosis in patients with a high clinical suspicion for nrAxSpA. The prevalence of nrAxSpA is similar to that of AS, but the former has a higher female preponderance. The rate of progression of nrAxSpA to the radiographic stage of disease (AS) ranges from 10% to 20% over 2 years. Current treatment strategies for nrAxSpA are the same as for AS and include non-steroidal anti-inflammatory drugs and inhibitors of tumor necrosis factor-alpha. While this review summarizes the current achievements in the field of nrAxSpA, further understanding of the epidemiology and natural history of the disease and, particularly, mechanisms of inflammation and subsequent new bone formation is essential for the development of new treatment strategies for nrAxSpA patients.

  10. Enhanced rate performance of flexible and stretchable linear supercapacitors based on polyaniline@Au@carbon nanotube with ultrafast axial electron transport

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Ding, Jianning; Zhou, Xiaoshuang; Zhang, Yang; Zhu, Wenjun; Liu, Zunfen; Ge, Shanhai; Yuan, Ningyi; Fang, Shaoli; Baughman, Ray H.

    2017-02-01

    Linear supercapacitors suffer a severe loss of capacity at high rates due to the trade-off of radial ion diffusion and axial electron transport. Optimizing axial conductivity of electrodes is a key to circumvent this trade-off. We report here the synthesis of Au nanograin decorated aligned multiwall carbon nanotube (CNT) sheets, followed by the incorporation of polyaniline (PANI). The embedded Au nanograins results in fast radial ion diffusion and enhance axial electron transport in the linear electrodes. The flexible linear solid supercapacitor fabricated by twisting two PANI@Au@CNT yarns exhibits an outstanding electrochemical performance with a total volumetric capacitance of ∼6 F cm-3 at scan rate up to 10 V s-1. Diameter of the electrode has little effect on volumetric capacitance even at high scan rates because of its high electrical conductivity. Highly stretchable supercapacitors with high rate performance and excellent cycling and stretching stability have been also fabricated using buckled linear electrodes made by wrapping PANI@Au@CNT sheet on elastic rubber fibers. The stretchable linear supercapacitor possesses a stable total volumetric capacitance of up to ∼0.2 F cm-3 at scan rate of 1 V s-1 and at 400% strain, and remarkable capacitance retention of about 95% over 1000 stretch/release cycles.

  11. Flow Split Venturi, Axially-Rotated Valve

    DOEpatents

    Walrath, David E.; Lindberg, William R.; Burgess, Robert K.; LaBelle, James

    2000-02-22

    The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. An axially aligned outlet may also increase the flow efficiency. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane. A seal separator may increase the useful life of the seal between the fixed and rotatable portions.

  12. Axial Flow Conditioning Device for Mitigating Instabilities

    NASA Technical Reports Server (NTRS)

    Ahuja, Vineet (Inventor); Birkbeck, Roger M. (Inventor); Hosangadi, Ashvin (Inventor)

    2017-01-01

    A flow conditioning device for incrementally stepping down pressure within a piping system is presented. The invention includes an outer annular housing, a center element, and at least one intermediate annular element. The outer annular housing includes an inlet end attachable to an inlet pipe and an outlet end attachable to an outlet pipe. The outer annular housing and the intermediate annular element(s) are concentrically disposed about the center element. The intermediate annular element(s) separates an axial flow within the outer annular housing into at least two axial flow paths. Each axial flow path includes at least two annular extensions that alternately and locally direct the axial flow radially outward and inward or radially inward and outward thereby inducing a pressure loss or a pressure gradient within the axial flow. The pressure within the axial flow paths is lower than the pressure at the inlet end and greater than the vapor pressure for the axial flow. The invention minimizes fluidic instabilities, pressure pulses, vortex formation and shedding, and/or cavitation during pressure step down to yield a stabilized flow within a piping system.

  13. Axial force measurement for esophageal function testing

    PubMed Central

    Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr

    2009-01-01

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the “golden standard” for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method. PMID:19132762

  14. The influence of the tangential velocity of inner rotating wall on axial velocity profile of flow through vertical annular pipe with rotating inner surface

    NASA Astrophysics Data System (ADS)

    Sharf, Abdusalam M.; Jawan, Hosen A.; Almabsout, Fthi A.

    2014-03-01

    In the oil and gas industries, understanding the behaviour of a flow through an annulus gap in a vertical position, whose outer wall is stationary whilst the inner wall rotates, is a significantly important issue in drilling wells. The main emphasis is placed on experimental (using an available rig) and computational (employing CFD software) investigations into the effects of the rotation speed of the inner pipe on the axial velocity profiles. The measured axial velocity profiles, in the cases of low axial flow, show that the axial velocity is influenced by the rotation speed of the inner pipe in the region of almost 33% of the annulus near the inner pipe, and influenced inversely in the rest of the annulus. The position of the maximum axial velocity is shifted from the centre to be nearer the inner pipe, by increasing the rotation speed. However, in the case of higher flow, as the rotation speed increases, the axial velocity is reduced and the position of the maximum axial velocity is skewed towards the centre of the annulus. There is a reduction of the swirl velocity corresponding to the rise of the volumetric flow rate.

  15. Volumetric modulated arc radiotherapy for esophageal cancer

    SciTech Connect

    Vivekanandan, Nagarajan; Sriram, Padmanaban; Syam Kumar, S.A.; Bhuvaneswari, Narayanan; Saranya, Kamalakannan

    2012-04-01

    A treatment planning study was performed to evaluate the performance of volumetric arc modulation with RapidArc (RA) against 3D conformal radiation therapy (3D-CRT) and conventional intensity-modulated radiation therapy (IMRT) techniques for esophageal cancer. Computed tomgraphy scans of 10 patients were included in the study. 3D-CRT, 4-field IMRT, and single-arc and double-arc RA plans were generated with the aim to spare organs at risk (OAR) and healthy tissue while enforcing highly conformal target coverage. The planning objective was to deliver 54 Gy to the planning target volume (PTV) in 30 fractions. Plans were evaluated based on target conformity and dose-volume histograms of organs at risk (lung, spinal cord, and heart). The monitor unit (MU) and treatment delivery time were also evaluated to measure the treatment efficiency. The IMRT plan improves target conformity and spares OAR when compared with 3D-CRT. Target conformity improved with RA plans compared with IMRT. The mean lung dose was similar in all techniques. However, RA plans showed a reduction in the volume of the lung irradiated at V{sub 20Gy} and V{sub 30Gy} dose levels (range, 4.62-17.98%) compared with IMRT plans. The mean dose and D{sub 35%} of heart for the RA plans were better than the IMRT by 0.5-5.8%. Mean V{sub 10Gy} and integral dose to healthy tissue were almost similar in all techniques. But RA plans resulted in a reduced low-level dose bath (15-20 Gy) in the range of 14-16% compared with IMRT plans. The average MU needed to deliver the prescribed dose by RA technique was reduced by 20-25% compared with IMRT technique. The preliminary study on RA for esophageal cancers showed improvements in sparing OAR and healthy tissue with reduced beam-on time, whereas only double-arc RA offered improved target coverage compared with IMRT and 3D-CRT plans.

  16. Ultrafast axial scanning for two-photon microscopy via a digital micromirror device and binary holography.

    PubMed

    Cheng, Jiyi; Gu, Chenglin; Zhang, Dapeng; Wang, Dien; Chen, Shih-Chi

    2016-04-01

    In this Letter, we present an ultrafast nonmechanical axial scanning method for two-photon excitation (TPE) microscopy based on binary holography using a digital micromirror device (DMD), achieving a scanning rate of 4.2 kHz, scanning range of ∼180  μm, and scanning resolution (minimum step size) of ∼270  nm. Axial scanning is achieved by projecting the femtosecond laser to a DMD programmed with binary holograms of spherical wavefronts of increasing/decreasing radii. To guide the scanner design, we have derived the parametric relationships between the DMD parameters (i.e., aperture and pixel size), and the axial scanning characteristics, including (1) maximum optical power, (2) minimum step size, and (3) scan range. To verify the results, the DMD scanner is integrated with a custom-built TPE microscope that operates at 60 frames per second. In the experiment, we scanned a pollen sample via both the DMD scanner and a precision z-stage. The results show the DMD scanner generates images of equal quality throughout the scanning range. The overall efficiency of the TPE system was measured to be ∼3%. With the high scanning rate, the DMD scanner may find important applications in random-access imaging or high-speed volumetric imaging that enables visualization of highly dynamic biological processes in 3D with submillisecond temporal resolution.

  17. Modeling axial compression fatigue in fiber ropes

    SciTech Connect

    Hearle, J.W.S.; Hobbs, R.E.; Overington, M.S.; Banfield, S.J.

    1995-12-31

    The modeling of long-term fatigue performance of twisted ropes has been extended to cover axial compression fatigue. This mode of failure has been observed in use and testing of ropes. It is characterized by sharp cooperative kinking of yarns, which leads to flex fatigue breakage of fibers. A model of pipeline buckling was modified to allow for plasticity in bending. An axial and lateral restraints, which influence the buckling, were derived from the existing rope mechanics model. Axial compression was introduced into the total computational model, in order to predict the form of buckling and the consequent fiber failure. An alternative use of the program is simply to detect conditions in which axial compression occurs as an indication of the occurrence of fatigue.

  18. Axial grading of inert matrix fuels

    SciTech Connect

    Recktenwald, G. D.; Deinert, M. R.

    2012-07-01

    Burning actinides in an inert matrix fuel to 750 MWd/kg IHM results in a significant reduction in transuranic isotopes. However, achieving this level of burnup in a standard light water reactor would require residence times that are twice that of uranium dioxide fuels. The reactivity of an inert matrix assembly at the end of life is less than 1/3 of its beginning of life reactivity leading to undesirable radial and axial power peaking in the reactor core. Here we show that axial grading of the inert matrix fuel rods can reduce peaking significantly. Monte Carlo simulations are used to model the assembly level power distributions in both ungraded and graded fuel rods. The results show that an axial grading of uranium dioxide and inert matrix fuels with erbium can reduces power peaking by more than 50% in the axial direction. The reduction in power peaking enables the core to operate at significantly higher power. (authors)

  19. High temperature co-axial winding transformers

    NASA Technical Reports Server (NTRS)

    Divan, Deepakraj M.; Novotny, Donald W.

    1993-01-01

    The analysis and design of co-axial winding transformers is presented. The design equations are derived and the different design approaches are discussed. One of the most important features of co-axial winding transformers is the fact that the leakage inductance is well controlled and can be made low. This is not the case in conventional winding transformers. In addition, the power density of co-axial winding transformers is higher than conventional ones. Hence, using co-axial winding transformers in a certain converter topology improves the power density of the converter. The design methodology used in meeting the proposed specifications of the co-axial winding transformer specifications are presented and discussed. The final transformer design was constructed in the lab. Co-axial winding transformers proved to be a good choice for high power density and high frequency applications. They have a more predictable performance compared with conventional transformers. In addition, the leakage inductance of the transformer can be controlled easily to suit a specific application. For space applications, one major concern is the extraction of heat from power apparatus to prevent excessive heating and hence damaging of these units. Because of the vacuum environment, the only way to extract heat is by using a cold plate. One advantage of co-axial winding transformers is that the surface area available to extract heat from is very large compared to conventional transformers. This stems from the unique structure of the co-axial transformer where the whole core surface area is exposed and can be utilized for cooling effectively. This is a crucial issue here since most of the losses are core losses.

  20. The Slotted Blade Axial-Flow Blower

    DTIC Science & Technology

    1955-09-01

    YORK 18, NEW YORK w is|’ .THE SLOTTED BLADE AXIAL-FLOW BLOVER AUG 0 1 13941J F Dr. H. E. Sheets, Member ASME Chief Research and Development Engineer ... blades of an axial flow blower. The subject of boundary-layer control has attracted considerable attention in respect to the isolated airfoil (1)1 but... blades . Flow through airfoils displays a region of laminar flow beginning at the leading edge. Further downstream, at approximately the location of the

  1. Axial forces in centrifugal compressor couplings

    NASA Astrophysics Data System (ADS)

    Ivanov, A. N.; Ivanov, N. M.; Yun, V. K.

    2017-08-01

    The article presents the results of the theoretical and experimental investigation of axial forces arising in the toothed and plate couplings of centrifugal compressor shaft lines. Additional loads on the thrust bearing are considered that can develop in the toothed couplings as a result of coupled rotors misalignment. Design relationships to evaluate the level of axial forces and recommendations for their reduction in the operating conditions are given.

  2. Planned Axial Reorientation Investigation on Sloshsat

    NASA Technical Reports Server (NTRS)

    Chato, David J.

    2000-01-01

    This paper details the design and logic of an experimental investigation to study axial reorientation in low gravity. The Sloshsat free-flyer is described. The planned axial reorientation experiments and test matrixes are presented. Existing analytical tools are discussed. Estimates for settling range from 64 to 1127 seconds. The planned experiments are modelled using computational fluid dynamics. These models show promise in reducing settling estimates and demonstrate the ability of pulsed high thrust settling to emulate lower thrust continuous firing.

  3. Volumetric image display for complex 3D data visualization

    NASA Astrophysics Data System (ADS)

    Tsao, Che-Chih; Chen, Jyh Shing

    2000-05-01

    A volumetric image display is a new display technology capable of displaying computer generated 3D images in a volumetric space. Many viewers can walk around the display and see the image from omni-directions simultaneously without wearing any glasses. The image is real and possesses all major elements in both physiological and psychological depth cues. Due to the volumetric nature of its image, the VID can provide the most natural human-machine interface in operations involving 3D data manipulation and 3D targets monitoring. The technology creates volumetric 3D images by projecting a series of profiling images distributed in the space form a volumetric image because of the after-image effect of human eyes. Exemplary applications in biomedical image visualization were tested on a prototype display, using different methods to display a data set from Ct-scans. The features of this display technology make it most suitable for applications that require quick understanding of the 3D relations, need frequent spatial interactions with the 3D images, or involve time-varying 3D data. It can also be useful for group discussion and decision making.

  4. Volumetric loss quantification using ultrasonic inductively coupled transducers

    NASA Astrophysics Data System (ADS)

    Gong, Peng; Hay, Thomas R.; Greve, David W.; Oppenheim, Irving J.

    2015-03-01

    The pulse-echo method is widely used for plate and pipe thickness measurement. However, the pulse echo method does not work well for detecting localized volumetric loss in thick-wall tubes, as created by erosion damage, when the morphology of volumetric loss is irregular and can reflect ultrasonic pulses away from the transducer, making it difficult to detect an echo. In this paper, we propose a novel method using an inductively coupled transducer to generate longitudinal waves propagating in a thick-wall aluminum tube for the volumetric loss quantification. In the experiment, longitudinal waves exhibit diffraction effects during the propagation which can be explained by the Huygens-Fresnel principle. The diffractive waves are also shown to be significantly delayed by the machined volumetric loss on the inside surface of the thick-wall aluminum tube. It is also shown that the inductively coupled transducers can generate and receive similar ultrasonic waves to those from wired transducers, and the inductively coupled transducers perform as well as the wired transducers in the volumetric loss quantification when other conditions are the same.

  5. Volumetric CT with sparse detector arrays (and application to Si-strip photon counters)

    NASA Astrophysics Data System (ADS)

    Sisniega, A.; Zbijewski, W.; Stayman, J. W.; Xu, J.; Taguchi, K.; Fredenberg, E.; Lundqvist, Mats; Siewerdsen, J. H.

    2016-01-01

    Novel x-ray medical imaging sensors, such as photon counting detectors (PCDs) and large area CCD and CMOS cameras can involve irregular and/or sparse sampling of the detector plane. Application of such detectors to CT involves undersampling that is markedly different from the commonly considered case of sparse angular sampling. This work investigates volumetric sampling in CT systems incorporating sparsely sampled detectors with axial and helical scan orbits and evaluates performance of model-based image reconstruction (MBIR) with spatially varying regularization in mitigating artifacts due to sparse detector sampling. Volumetric metrics of sampling density and uniformity were introduced. Penalized-likelihood MBIR with a spatially varying penalty that homogenized resolution by accounting for variations in local sampling density (i.e. detector gaps) was evaluated. The proposed methodology was tested in simulations and on an imaging bench based on a Si-strip PCD (total area 5 cm  ×  25 cm) consisting of an arrangement of line sensors separated by gaps of up to 2.5 mm. The bench was equipped with translation/rotation stages allowing a variety of scanning trajectories, ranging from a simple axial acquisition to helical scans with variable pitch. Statistical (spherical clutter) and anthropomorphic (hand) phantoms were considered. Image quality was compared to that obtained with a conventional uniform penalty in terms of structural similarity index (SSIM), image uniformity, spatial resolution, contrast, and noise. Scan trajectories with intermediate helical width (~10 mm longitudinal distance per 360° rotation) demonstrated optimal tradeoff between the average sampling density and the homogeneity of sampling throughout the volume. For a scan trajectory with 10.8 mm helical width, the spatially varying penalty resulted in significant visual reduction of sampling artifacts, confirmed by a 10% reduction in minimum SSIM (from 0.88 to 0.8) and a 40

  6. Volumetric CT with sparse detector arrays (and application to Si-strip photon counters)

    PubMed Central

    Sisniega, A; Zbijewski, W; Stayman, J W; Xu, J; Taguchi, K; Fredenberg, E; Lundqvist, Mats; Siewerdsen, J H

    2016-01-01

    Novel x-ray medical imaging sensors, such as photon counting detectors (PCDs) and large area CCD and CMOS cameras can involve irregular and/or sparse sampling of the detector plane. Application of such detectors to CT involves undersampling that is markedly different from the commonly considered case of sparse angular sampling. This work investigates volumetric sampling in CT systems incorporating sparsely sampled detectors with axial and helical scan orbits and evaluates performance of model-based image reconstruction (MBIR) with spatially varying regularization in mitigating artifacts due to sparse detector sampling. Volumetric metrics of sampling density and uniformity were introduced. Penalized-likelihood MBIR with a spatially varying penalty that homogenized resolution by accounting for variations in local sampling density (i.e. detector gaps) was evaluated. The proposed methodology was tested in simulations and on an imaging bench based on a Si-strip PCD (total area 5 cm × 25 cm) consisting of an arrangement of line sensors separated by gaps of up to 2.5 mm. The bench was equipped with translation/rotation stages allowing a variety of scanning trajectories, ranging from a simple axial acquisition to helical scans with variable pitch. Statistical (spherical clutter) and anthropomorphic (hand) phantoms were considered. Image quality was compared to that obtained with a conventional uniform penalty in terms of structural similarity index (SSIM), image uniformity, spatial resolution, contrast, and noise. Scan trajectories with intermediate helical width (~10 mm longitudinal distance per 360° rotation) demonstrated optimal tradeoff between the average sampling density and the homogeneity of sampling throughout the volume. For a scan trajectory with 10.8 mm helical width, the spatially varying penalty resulted in significant visual reduction of sampling artifacts, confirmed by a 10% reduction in minimum SSIM (from 0.88 to 0.8) and a 40% reduction in the

  7. STATIC VS PROSPECTIVE GATED, NON-BREATH HOLD VOLUMETRIC MDCT IMAGING OF THE LUNGS

    PubMed Central

    Saba, Osama I.; Chon, Deokiee; Beck, Kenneth; McLennan, Geoffrey; Sieren, Jered; Reinhardt, Joseph; Hoffman, Eric A.

    2005-01-01

    Rationale and Objectives: We seek to establish lung imaging methods which provide for the ability to image the lung under dynamic, non-breath hold conditions while providing “virtual breath hold,” quantifiable volumetric image data sets. We use static, breath hold images as the gold standard for evaluating these virtual breath hold images in both a phantom and sheep. Materials and Methods: We have developed axial methods for gating image acquisition to multiple points in the respiratory cycle interleaved with incremental table stepping during multidetector-row CT (MDCT) scanning. Datasets are generated over multiple breaths, providing volume images representative of multiple points within a respiratory cycle. To determine the reproducibility and accuracy of the methods , 6 anesthetized sheep were studied by MDCT in non-gated and airway-pressure (Pawy)-gated modes where Pawy was 0, 7 and 15 cmH2O. Results: No significant differences were found between the coefficient of variation in air volume measured from repeated static scans (1.74±1.78%), gated scans: Inspiratory gated (1.2±0.44%) or expiratory-gated (1.39±0.98%), or between static (1.74±1.78%) and gated (1.39+/-0.98%) scanning at similar Pawy (p>0.1). Measured air volumes were larger from static vs. gated scans by 5.85±3.77% at 7cmH2O and 4.45±3.6% at 15cmHL2O Pawy (p<0.05) consistent with hysteresis. Differences between air volumes at 7 and 15 cmH2O measured from either static or gated scans or that delivered by a supersyringe were insignificant (p<0.05). Visual accuracy of 3D anatomic geometry was achieved, and landmark certainty was within 1mm across respiratory cycles. Conclusion: A method has been demonstrated which provides for accurate gating to respiratory signals during axial scanning. High resolution volumetric image datasets are achievable while the scanned subject is breathing.Images are quantitatively similar to breath hold images with differences likely explained by known P-V hysteresis

  8. Volumetric CT with sparse detector arrays (and application to Si-strip photon counters).

    PubMed

    Sisniega, A; Zbijewski, W; Stayman, J W; Xu, J; Taguchi, K; Fredenberg, E; Lundqvist, Mats; Siewerdsen, J H

    2016-01-07

    Novel x-ray medical imaging sensors, such as photon counting detectors (PCDs) and large area CCD and CMOS cameras can involve irregular and/or sparse sampling of the detector plane. Application of such detectors to CT involves undersampling that is markedly different from the commonly considered case of sparse angular sampling. This work investigates volumetric sampling in CT systems incorporating sparsely sampled detectors with axial and helical scan orbits and evaluates performance of model-based image reconstruction (MBIR) with spatially varying regularization in mitigating artifacts due to sparse detector sampling. Volumetric metrics of sampling density and uniformity were introduced. Penalized-likelihood MBIR with a spatially varying penalty that homogenized resolution by accounting for variations in local sampling density (i.e. detector gaps) was evaluated. The proposed methodology was tested in simulations and on an imaging bench based on a Si-strip PCD (total area 5 cm  ×  25 cm) consisting of an arrangement of line sensors separated by gaps of up to 2.5 mm. The bench was equipped with translation/rotation stages allowing a variety of scanning trajectories, ranging from a simple axial acquisition to helical scans with variable pitch. Statistical (spherical clutter) and anthropomorphic (hand) phantoms were considered. Image quality was compared to that obtained with a conventional uniform penalty in terms of structural similarity index (SSIM), image uniformity, spatial resolution, contrast, and noise. Scan trajectories with intermediate helical width (~10 mm longitudinal distance per 360° rotation) demonstrated optimal tradeoff between the average sampling density and the homogeneity of sampling throughout the volume. For a scan trajectory with 10.8 mm helical width, the spatially varying penalty resulted in significant visual reduction of sampling artifacts, confirmed by a 10% reduction in minimum SSIM (from 0.88 to 0.8) and a 40

  9. Split Venturi, Axially-Rotated Valve

    DOEpatents

    Walrath, David E.; Lindberg, William R.; Burgess, Robert K.

    2000-08-29

    The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane.

  10. Wave propagation in axially moving periodic strings

    NASA Astrophysics Data System (ADS)

    Sorokin, Vladislav S.; Thomsen, Jon Juel

    2017-04-01

    The paper deals with analytically studying transverse waves propagation in an axially moving string with periodically modulated cross section. The structure effectively models various relevant technological systems, e.g. belts, thread lines, band saws, etc., and, in particular, roller chain drives for diesel engines by capturing both their spatial periodicity and axial motion. The Method of Varying Amplitudes is employed in the analysis. It is shown that the compound wave traveling in the axially moving periodic string comprises many components with different frequencies and wavenumbers. This is in contrast to non-moving periodic structures, for which all components of the corresponding compound wave feature the same frequency. Due to this "multi-frequency" character of the wave motion, the conventional notion of frequency band-gaps appears to be not applicable for the moving periodic strings. Thus, for such structures, by frequency band-gaps it is proposed to understand frequency ranges in which the primary component of the compound wave attenuates. Such frequency band-gaps can be present for a moving periodic string, but only if its axial velocity is lower than the transverse wave speed, and, the higher the axial velocity, the narrower the frequency band-gaps. The revealed effects could be of potential importance for applications, e.g. they indicate that due to spatial inhomogeneity, oscillations of axially moving periodic chains always involve a multitude of frequencies.

  11. A prototype table-top inverse-geometry volumetric CT system.

    PubMed

    Schmidt, Taly Gilat; Star-Lack, Josh; Bennett, N Robert; Mazin, Samuel R; Solomon, Edward G; Fahrig, Rebecca; Pelc, Norbert J

    2006-06-01

    A table-top volumetric CT system has been implemented that is able to image a 5-cm-thick volume in one circular scan with no cone-beam artifacts. The prototype inverse-geometry CT (IGCT) scanner consists of a large-area, scanned x-ray source and a detector array that is smaller in the transverse direction. The IGCT geometry provides sufficient volumetric sampling because the source and detector have the same axial, or slice direction, extent. This paper describes the implementation of the table-top IGCT scanner, which is based on the NexRay Scanning-Beam Digital X-ray system (NexRay, Inc., Los Gatos, CA) and an investigation of the system performance. The alignment and flat-field calibration procedures are described, along with a summary of the reconstruction algorithm. The resolution and noise performance of the prototype IGCT system are studied through experiments and further supported by analytical predictions and simulations. To study the presence of cone-beam artifacts, a "Defrise" phantom was scanned on both the prototype IGCT scanner and a micro CT system with a +/-5 cone angle for a 4.5-cm volume thickness. Images of inner ear specimens are presented and compared to those from clinical CT systems. Results showed that the prototype IGCT system has a 0.25-mm isotropic resolution and that noise comparable to that from a clinical scanner with equivalent spatial resolution is achievable. The measured MTF and noise values agreed reasonably well with theoretical predictions and computer simulations. The IGCT system was able to faithfully reconstruct the laminated pattern of the Defrise phantom while the micro CT system suffered severe cone-beam artifacts for the same object. The inner ear acquisition verified that the IGCT system can image a complex anatomical object, and the resulting images exhibited more high-resolution details than the clinical CT acquisition. Overall, the successful implementation of the prototype system supports the IGCT concept for single

  12. Modelling volumetric growth in a thick walled fibre reinforced artery

    NASA Astrophysics Data System (ADS)

    Eriksson, T. S. E.; Watton, P. N.; Luo, X. Y.; Ventikos, Y.

    2014-12-01

    A novel framework for simulating growth and remodelling (G&R) of a fibre-reinforced artery, including volumetric adaption, is proposed. We show how to implement this model into a finite element framework and propose and examine two underlying assumptions for modelling growth, namely constant individual density (CID) or adaptive individual density (AID). Moreover, we formulate a novel approach which utilises a combination of both AID and CID to simulate volumetric G&R for a tissue composed of several different constituents. We consider a special case of the G&R of an artery subjected to prescribed elastin degradation and we theorise on the assumptions and suitability of CID, AID and the mixed approach for modelling arterial biology. For simulating the volumetric changes that occur during aneurysm enlargement, we observe that it is advantageous to describe the growth of collagen using CID whilst it is preferable to model the atrophy of elastin using AID.

  13. Automated Segmentation and Shape Characterization of Volumetric Data

    PubMed Central

    Galinsky, Vitaly L.; Frank, Lawrence R.

    2015-01-01

    Characterization of complex shapes embedded within volumetric data is an important step in a wide range of applications. Standard approaches to this problem employ surface based methods that require inefficient, time consuming, and error prone steps of surface segmentation and inflation to satisfy the uniqueness or stability of subsequent surface fitting algorithms. Here we present a novel method based on a spherical wave decomposition (SWD) of the data that overcomes several of these limitations by directly analyzing the entire data volume, obviating the segmentation, inflation, and surface fitting steps, significantly reducing the computational time and eliminating topological errors while providing a more detailed quantitative description based upon a more complete theoretical framework of volumetric data. The method is demonstrated and compared to the current state-of-the-art neuroimaging methods for segmentation and characterization of volumetric magnetic resonance imaging data of the human brain. PMID:24521852

  14. A high volume, high throughput volumetric sorption analyzer

    NASA Astrophysics Data System (ADS)

    Soo, Y. C.; Beckner, M.; Romanos, J.; Wexler, C.; Pfeifer, P.; Buckley, P.; Clement, J.

    2011-03-01

    In this talk we will present an overview of our new Hydrogen Test Fixture (HTF) constructed by the Midwest Research Institute for The Alliance for Collaborative Research in Alternative Fuel Technology to test activated carbon monoliths for hydrogen gas storage. The HTF is an automated, computer-controlled volumetric instrument for rapid screening and manipulation of monoliths under an inert atmosphere (to exclude degradation of carbon from exposure to oxygen). The HTF allows us to measure large quantity (up to 500 g) of sample in a 0.5 l test tank, making our results less sensitive to sample inhomogeneity. The HTF can measure isotherms at pressures ranging from 1 to 300 bar at room temperature. For comparison, other volumetric instruments such as Hiden Isochema's HTP-1 Volumetric Analyser can only measure carbon samples up to 150 mg at pressures up to 200 bar. Work supported by the US DOD Contract # N00164-08-C-GS37.

  15. Full-spectrum volumetric solar thermal conversion via photonic nanofluids.

    PubMed

    Liu, Xianglei; Xuan, Yimin

    2017-07-24

    Volumetric solar thermal conversion is an emerging technique for a plethora of applications such as solar thermal power generation, desalination, and solar water splitting. However, achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge. In this work, full-spectrum volumetric solar thermal conversion is demonstrated over a thin layer of the proposed 'photonic nanofluids'. The underlying mechanism is found to be the photonic superposition of core resonances, shell plasmons, and core-shell resonances at different wavelengths, whose coexistence is enabled by the broken symmetry of specially designed composite nanoparticles, i.e., Janus nanoparticles. The solar thermal conversion efficiency can be improved by 10.8% compared with core-shell nanofluids. The extinction coefficient of Janus dimers with various configurations is also investigated to unveil the effects of particle couplings. This work provides the possibility to achieve full-spectrum volumetric solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

  16. Cost-effectiveness of volumetric alcohol taxation in Australia.

    PubMed

    Byrnes, Joshua M; Cobiac, Linda J; Doran, Christopher M; Vos, Theo; Shakeshaft, Anthony P

    2010-04-19

    To estimate the potential health benefits and cost savings of an alcohol tax rate that applies equally to all alcoholic beverages based on their alcohol content (volumetric tax) and to compare the cost savings with the cost of implementation. Mathematical modelling of three scenarios of volumetric alcohol taxation for the population of Australia: (i) no change in deadweight loss, (ii) no change in tax revenue, and (iii) all alcoholic beverages taxed at the same rate as spirits. Estimated change in alcohol consumption, tax revenue and health benefit. The estimated cost of changing to a volumetric tax rate is $18 million. A volumetric tax that is deadweight loss-neutral would increase the cost of beer and wine and reduce the cost of spirits, resulting in an estimated annual increase in taxation revenue of $492 million and a 2.77% reduction in annual consumption of pure alcohol. The estimated net health gain would be 21 000 disability-adjusted life-years (DALYs), with potential cost offsets of $110 million per annum. A tax revenue-neutral scenario would result in an 0.05% decrease in consumption, and a tax on all alcohol at a spirits rate would reduce consumption by 23.85% and increase revenue by $3094 million [corrected]. All volumetric tax scenarios would provide greater health benefits and cost savings to the health sector than the existing taxation system, based on current understandings of alcohol-related health effects. An equalized volumetric tax that would reduce beer and wine consumption while increasing the consumption of spirits would need to be approached with caution. Further research is required to examine whether alcohol-related health effects vary by type of alcoholic beverage independent of the amount of alcohol consumed to provide a strong evidence platform for alcohol taxation policies.

  17. Multiple sparse volumetric priors for distributed EEG source reconstruction.

    PubMed

    Strobbe, Gregor; van Mierlo, Pieter; De Vos, Maarten; Mijović, Bogdan; Hallez, Hans; Van Huffel, Sabine; López, José David; Vandenberghe, Stefaan

    2014-10-15

    We revisit the multiple sparse priors (MSP) algorithm implemented in the statistical parametric mapping software (SPM) for distributed EEG source reconstruction (Friston et al., 2008). In the present implementation, multiple cortical patches are introduced as source priors based on a dipole source space restricted to a cortical surface mesh. In this note, we present a technique to construct volumetric cortical regions to introduce as source priors by restricting the dipole source space to a segmented gray matter layer and using a region growing approach. This extension allows to reconstruct brain structures besides the cortical surface and facilitates the use of more realistic volumetric head models including more layers, such as cerebrospinal fluid (CSF), compared to the standard 3-layered scalp-skull-brain head models. We illustrated the technique with ERP data and anatomical MR images in 12 subjects. Based on the segmented gray matter for each of the subjects, cortical regions were created and introduced as source priors for MSP-inversion assuming two types of head models. The standard 3-layered scalp-skull-brain head models and extended 4-layered head models including CSF. We compared these models with the current implementation by assessing the free energy corresponding with each of the reconstructions using Bayesian model selection for group studies. Strong evidence was found in favor of the volumetric MSP approach compared to the MSP approach based on cortical patches for both types of head models. Overall, the strongest evidence was found in favor of the volumetric MSP reconstructions based on the extended head models including CSF. These results were verified by comparing the reconstructed activity. The use of volumetric cortical regions as source priors is a useful complement to the present implementation as it allows to introduce more complex head models and volumetric source priors in future studies.

  18. Hyperquenched hyaloclastites from Axial Seamount

    NASA Astrophysics Data System (ADS)

    Zezin, D.; Helo, C.; Richard, D.; Clague, D. A.; Dingwell, D. B.; Stix, J.

    2009-12-01

    We determined apparent cooling rates for basaltic hyaloclastites from Axial caldera, Juan de Fuca Ridge. Samples originate from different stratigraphic layers within the unconsolidated volcaniclastic sequences, on flanks of the volcanic edifice. Water depth is ~1400 m below sea level. The hyaloclastite glass fragments comprise two principal morphologies: (1) angular fragments, and (2) thin glassy melt films interpreted as bubble walls, called deep-sea limu o Pele. A natural cooling rate was estimated for each sample of ~50 carefully selected glass shards. The heat capacity was first measured with a differential scanning calorimeter in two heating scans with heating rates of 20 K/min, and a matching cooling rate between those scans. The fictive temperatures Tf were then determined from both heating cycles, and the natural cooling rate derived by the non-Arrhenian relationship between Tf and cooling rate. All samples display hyperquenched states, manifested in a strong exothermic energy release during the initial heating cycle before reaching the glass transition. Cooling rates range from 10 6.73 K/s to 10 3.94 K/s for the limu, and 10 4.92 K/s to 10 2.34 K/s for the angular fragments. Almost all samples of limu shards show elevated cooling rates compared to their angular counterparts of comparable grain mass. In addition, the exothermic part of the enthalpy curves reveal two superimposed relaxation domains, the main broad exothermal peak, ranging from ~350 K to the onset of the glass transition, and a small subordinate peak/shoulder occurring between 550 K and 700 K. The magnitude of the latter varies from clearly identifiable to nearly absent, and tends to be more pronounced in curves obtained from angular fragments. The main exothermal peak is related to the frozen-in structure of the glass and consequently to its thermal history when passing through the glass transition. The subordinate peak may represent strain rate-induced and tensile stress accumulation

  19. Volumetric Hall Effect Tomography – A Feasibility Study

    PubMed Central

    Wen, Han

    2010-01-01

    Hall effect imaging is an ultrasound-based method of mapping spatial variations in the dielectric constants of an acoustically-uniform sample. This paper presents three-dimensional Hall effect images of phantoms obtained by scanning a single transducer across a two-dimensional grid, effectively simulating two-dimensional phased-array signal reception. The experiments demonstrate the feasibility of volumetric Hall effect tomography and show the advantage of volumetric scans over planar scans. The images reflect several limitations of the current scanning method and point to directions for further hardware development. The inherent limitations of Hall effect imaging are also discussed in light of these results. PMID:10604800

  20. Neurologic applications of whole-brain volumetric multidetector computed tomography.

    PubMed

    Snyder, Kenneth V; Mokin, Maxim; Bates, Vernice E

    2014-02-01

    The introduction of computed tomography (CT) scanning in the 1970s revolutionized the way clinicians could diagnose and treat stroke. Subsequent advances in CT technology significantly reduced radiation dose, reduced metallic artifact, and achieved speeds that enable dynamic functional studies. The recent addition of whole-brain volumetric CT perfusion technology has given clinicians a powerful tool to assess parenchymal perfusion parameters as well as visualize dynamic changes in blood vessel flow throughout the brain during a single cardiac cycle. This article reviews clinical applications of volumetric multimodal CT that helped to guide and manage care.

  1. Subcortical and cerebellar volumetric deficits in paediatric sickle cell anaemia.

    PubMed

    Kawadler, Jamie M; Clayden, Jonathan D; Kirkham, Fenella J; Cox, Timothy C; Saunders, Dawn E; Clark, Chris A

    2013-11-01

    Sickle cell anaemia (SCA) is associated with silent cerebral infarction (SCI), affecting white and cortical grey matter, but there are few data on subcortical volumes. We analysed retrospective magnetic resonance imaging (MRI) data in 26 SCA patients and 20 controls, comparing mean subcortical volumes between three groups: controls, SCA with SCI (n = 13) and SCA without visible abnormality (n = 13). Specific volumetric differences were found in the hippocampus, amygdala, pallidum, caudate, putamen, thalamus, and cerebellum. This is the first study to demonstrate subcortical volume change in SCA, with the most severe volumetric deficits occurring in children with SCI seen on MRI.

  2. Volumetric Pricing of Agricultural Water Supplies: A Case Study

    NASA Astrophysics Data System (ADS)

    Griffin, Ronald C.; Perry, Gregory M.

    1985-07-01

    Models of water consumption by rice producers are conceptualized and then estimated using cross-sectional time series data obtained from 16 Texas canal operators for the years 1977-1982. Two alternative econometric models demonstrate that both volumetric and flat rate water charges are strongly and inversely related to agricultural water consumption. Nonprice conservation incentives accompanying flat rates are hypothesized to explain the negative correlation of flat rate charges and water consumption. Application of these results suggests that water supply organizations in the sample population converting to volumetric pricing will generally reduce water consumption.

  3. Volumetric Hall effect tomography--a feasibility study.

    PubMed

    Wen, H

    1999-07-01

    Hall effect imaging is an ultrasound-based method of mapping spatial variations in the dielectric constants of an acoustically-uniform sample. This paper presents three-dimensional Hall effect images of phantoms obtained by scanning a single transducer across a two-dimensional grid, effectively simulating two-dimensional phased-array signal reception. The experiments demonstrate the feasibility of volumetric Hall effect tomography and show the advantage of volumetric scans over planar scans. The images reflect several limitations of the current scanning method and point to directions for further hardware development. The inherent limitations of Hall effect imaging are also discussed in light of these results.

  4. SU-E-I-10: Investigation On Detectability of a Small Target for Different Slice Direction of a Volumetric Cone Beam CT Image

    SciTech Connect

    Lee, C; Han, M; Baek, J

    2015-06-15

    Purpose: To investigate the detectability of a small target for different slice direction of a volumetric cone beam CT image and its impact on dose reduction. Methods: Analytic projection data of a sphere object (1 mm diameter, 0.2/cm attenuation coefficient) were generated and reconstructed by FDK algorithm. In this work, we compared the detectability of the small target from four different backprojection Methods: hanning weighted ramp filter with linear interpolation (RECON 1), hanning weighted ramp filter with Fourier interpolation (RECON2), ramp filter with linear interpolation (RECON 3), and ramp filter with Fourier interpolation (RECON4), respectively. For noise simulation, 200 photons per measurement were used, and the noise only data were reconstructed using FDK algorithm. For each reconstructed volume, axial and coronal slice were extracted and detection-SNR was calculated using channelized Hotelling observer (CHO) with dense difference-of-Gaussian (D-DOG) channels. Results: Detection-SNR of coronal images varies for different backprojection methods, while axial images have a similar detection-SNR. Detection-SNR{sup 2} ratios of coronal and axial images in RECON1 and RECON2 are 1.33 and 1.15, implying that the coronal image has a better detectability than axial image. In other words, using coronal slices for the small target detection can reduce the patient dose about 33% and 15% compared to using axial slices in RECON 1 and RECON 2. Conclusion: In this work, we investigated slice direction dependent detectability of a volumetric cone beam CT image. RECON 1 and RECON 2 produced the highest detection-SNR, with better detectability in coronal slices. These results indicate that it is more beneficial to use coronal slice to improve detectability of a small target in a volumetric cone beam CT image. This research was supported by the MSIP (Ministry of Science, ICT and Future Planning), Korea, under the IT Consilience Creative Program (NIPA-2014-H0201

  5. Complete Volumetric Decomposition of Individual Trabecular Plates and Rods and Its Morphological Correlations With Anisotropic Elastic Moduli in Human Trabecular Bone

    PubMed Central

    Liu, X Sherry; Sajda, Paul; Saha, Punam K; Wehrli, Felix W; Bevill, Grant; Keaveny, Tony M; Guo, X Edward

    2008-01-01

    Trabecular plates and rods are important microarchitectural features in determining mechanical properties of trabecular bone. A complete volumetric decomposition of individual trabecular plates and rods was used to assess the orientation and morphology of 71 human trabecular bone samples. The ITS-based morphological analyses better characterize microarchitecture and help predict anisotropic mechanical properties of trabecular bone. Introduction Standard morphological analyses of trabecular architecture lack explicit segmentations of individual trabecular plates and rods. In this study, a complete volumetric decomposition technique was developed to segment trabecular bone microstructure into individual plates and rods. Contributions of trabecular type–associated morphological parameters to the anisotropic elastic moduli of trabecular bone were studied. Materials and Methods Seventy-one human trabecular bone samples from the femoral neck (FN), tibia, and vertebral body (VB) were imaged using μCT or serial milling. Complete volumetric decomposition was applied to segment trabecular bone microstructure into individual plates and rods. The orientation of each individual trabecula was determined, and the axial bone volume fractions (aBV/TV), axially aligned bone volume fraction along each orthotropic axis, were correlated with the elastic moduli. The microstructural type–associated morphological parameters were derived and compared with standard morphological parameters. Their contributions to the anisotropic elastic moduli, calculated by finite element analysis (FEA), were evaluated and compared. Results The distribution of trabecular orientation suggested that longitudinal plates and transverse rods dominate at all three anatomic sites. aBV/TV along each axis, in general, showed a better correlation with the axial elastic modulus (r 2 = 0.95∼0.99) compared with BV/TV (r 2 = 0.93∼0.94). The plate-associated morphological parameters generally showed higher

  6. Optimization of residual heat removal pump axial thrust and axial bearing

    SciTech Connect

    Schubert, F.

    1996-12-01

    The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.

  7. Axial eye length after retinal detachment surgery.

    PubMed

    Vukojević, Nenad; Sikić, Jakov; Curković, Tihomir; Juratovac, Zlatko; Katusić, Damir; Sarić, Borna; Jukić, Tomislav

    2005-01-01

    Changes in the eye axial diameter were studied to assess the eye globe impact of conventional operation for retinal detachment. The study included 69 eyes in 69 patients operated on for rhegmatogenous retinal detachment. There were 46.4% of men and 53.6% of women, mean age 52.7 (+/- 15.21) years. Results of preoperative and postoperative ultrasonographic measurement of axial diameter are presented. The mean preoperative and postoperative eye axial diameter was 23.69 (+/- 1.84) mm and 24.43 (+/- 1.91) mm, respectively. Postoperative results showed the axial eye length to increase by a mean of 0.74 (+/- 0.44) mm, yielding a statistically significant difference from the preoperative measurement (p < 0.001). The mean myopia induced by this eyeball elongation was 1.77 D. The encircling band with and without segmental buckling used in surgical repair of retinal detachment creates circular and segmental indentation of the eyeball, thus increasing its axial length. The myopia induced by elongation of the eyeball results in considerable myopia, which requires appropriate correction in the early postoperative period to achieve favorable vision rehabilitation.

  8. Axial flow gas turbine engine combustor

    SciTech Connect

    Shekleton, J.R.; Sawyer, K.W.

    1991-02-19

    This patent describes a gas turbine engine. It comprises: radial compressor means for compressing air entering through a compressor inlet opening; axial turbine means in axially spaced relation to the radial compressor means; the radial compressor means being operatively associated with the axial turbine means; radial combustor means intermediate the radial compressor means and axial turbine means; turbine nozzle means proximate the axial turbine means for directing gases of combustion thereto; the radial combustor means defining a radial combustion space in communication with both the radial compressor means and the turbine nozzle means. The radial combustor means including means for introducing compressed air generally tangentially into the radial combustion space upstream of the turbine nozzle means and at a point radially outwardly of the turbine nozzle means and the turbine nozzle means being disposed radially inwardly of the radial combustion space to define a generally radial flow path therebetween. The radial combustor means generating the gases of combustion by combusting fuel from a source and air from the radial compressor means; and fuel injection means operatively associated with the radial combustor means radially outwardly of the turbine nozzle means for injecting a fuel/air mixture generally tangentially into the radial combustion space; whereby a tangential swirl flow is established within the radial combustion space.

  9. Are axial and radial flow chromatography different?

    PubMed

    Besselink, Tamara; van der Padt, Albert; Janssen, Anja E M; Boom, Remko M

    2013-01-04

    Radial flow chromatography can be a solution for scaling up a packed bed chromatographic process to larger processing volumes. In this study we compared axial and radial flow affinity chromatography both experimentally and theoretically. We used an axial flow column and a miniaturized radial flow column with a ratio of 1.8 between outer and inner surface area, both with a bed height of 5 cm. The columns were packed with affinity resin to adsorb BSA. The average velocity in the columns was set equal. No difference in performance between the two columns could be observed. To gain more insight into the design of a radial flow column, the velocity profile and resin distribution in the radial flow column were calculated. Using mathematical models we found that the breakthrough performance of radial flow chromatography is very similar to axial flow when the ratio between outer and inner radius of the radial flow column is around 2. When this ratio is increased, differences become more apparent, but remain small. However, the ratio does have a significant influence on the velocity profile inside the resin bed, which directly influences the pressure drop and potentially resin compression, especially at higher values for this ratio. The choice between axial and radial flow will be based on cost price, footprint and packing characteristics. For small-scale processes, axial flow chromatography is probably the best choice, for resin volumes of at least several tens of litres, radial flow chromatography may be preferable.

  10. Axial super-resolution evanescent wave tomography.

    PubMed

    Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-12-01

    Optical tomographic reconstruction of a three-dimensional (3D) nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography method that enables the use of regular evanescent wave microscopes like the total internal reflection fluorescence microscope beyond surface imaging and achieve a tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of 3D fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by one-dimensional (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of ∼130  nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like stochastic optical reconstruction microscopy and can also be adapted for THz and microwave near-field tomography.

  11. Animated axial surface mapping: The multimedia companion

    SciTech Connect

    Hook, S.C.; Shaw, J.H.; Suppe, J.

    1995-09-01

    This newly expanded version of AAPG`s first DataShare Disk brings to life the concepts and applications of a new method of structural trend analysis. Through the dynamic use of color, sound, animation, and humor, this multimedia companion to the May 1994 article on Axial Surface Mapping introduces the reader (or viewer) to the concepts of rigid-block translation, fault-bend folding, and axial surface mapping. Animated models of growing fault-bend folds allow the viewer to see in four dimensions. The axial surface map shows the horizontal plane; the folding lines show depth planes; and the animations show the structure and its two-dimensional map changing with time and increasing slip. The animations create theoretical map patterns under varying, but controlled conditions that can be compared to axial surface maps from real data. The model patterns are then used to interpret seismic data and axial surface maps from a producing gas field in offshore California and from an exploration play in Pennsylvania.

  12. Axial super-resolution evanescent wave tomography

    NASA Astrophysics Data System (ADS)

    Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-12-01

    Optical tomographic reconstruction of a 3D nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography (AxSET) method that enables the use of regular evanescent wave microscopes like Total Internal Reflection Fluorescence Microscope (TIRF) beyond surface imaging, and achieve tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of three-dimensional fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by 1D (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of $\\sim$130 nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like STORM and can also be adapted for THz and microwave near-field tomography.

  13. Axial resolution enhancement of third harmonic generation microscopy by harmonic focal point axial modulation

    NASA Astrophysics Data System (ADS)

    Mozdoor Dashtabi, Mahdi; Arabanian, Atoosa Sadat; Massudi, Reza

    2017-02-01

    Harmonic focal point axial modulation (h-FPAM) in nonlinear optical microscopy is introduced and used to enhance the axial resolution and the signal to background ratio by modulating the focal point of a beam of femtosecond pulses train along the axial direction and phase sensitively filtering the resulting signals using a lock-in amplifier. Axial resolution enhancement factor of 2.05 is acquired in 2f detection mode for the third harmonic generation microscopy of glass-oil interfaces. This technique also resolves the image interpretation problem of the fundamental harmonic FPAM technique. Moreover, the potential of this technique for axial sectioning is demonstrated by acquiring images from a red blood cell.

  14. Rapid release of growth factors regenerates force output in volumetric muscle loss injuries

    PubMed Central

    Grasman, Jonathan M.; Do, Duc M.; Page, Raymond L.; Pins, George D.

    2015-01-01

    A significant challenge in the design and development of biomaterial scaffolds is to incorporate mechanical and biochemical cues to direct organized tissue growth. In this study, we investigated the effect of hepatocyte growth factor (HGF) loaded, crosslinked fibrin (EDCn-HGF) microthread scaffolds on skeletal muscle regeneration in a mouse model of volumetric muscle loss (VML). The rapid, sustained release of HGF significantly enhanced the force production of muscle tissue 60 days after injury, recovering more than 200% of the force output relative to measurements recorded immediately after injury. HGF delivery increased the number of differentiating myoblasts 14 days after injury, and supported an enhanced angiogenic response. The architectural morphology of microthread scaffolds supported the ingrowth of nascent myofibers into the wound site, in contrast to fibrin gel implants which did not support functional regeneration. Together, these data suggest that EDCn-HGF microthreads recapitulate several of the regenerative cues lost in VML injuries, promote remodeling of functional muscle tissue, and enhance the functional regeneration of skeletal muscle. Further, by strategically incorporating specific biochemical factors and precisely tuning the structural and mechanical properties of fibrin microthreads, we have developed a powerful platform technology that may enhance regeneration in other axially aligned tissues. PMID:26344363

  15. In vivo volumetric imaging of the human upper eyelid with ultrahigh-resolution optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Bizheva, Kostadinka; Lee, Patrick; Sorbara, Luigina; Hutchings, Natalie; Simpson, Trefford

    2010-07-01

    The upper eyelid is a biological tissue with complex structure, essential for the maintenance of an optically clear ocular surface due to its physical (blinking) effect. The Meibomian glands (MGs) are structures that lie beneath the surface of the inner eyelid and are partially responsible for the production of the superficial oily layer of the tear film. The MGs are only superficially visible under magnification when the eyelid is everted. We present for the first time in vivo 3-D images of healthy and inflamed human MGs. Tomograms were acquired from the tarsal plate of everted human eyelids with a 1060-nm ultrahigh-resolution optical coherence tomography (UHOCT) system, with ~3 μm×10 μm (axial×lateral) resolution in biological tissue at the rate of 91,911 A-scans/s. Comparison with histology shows that the UHOCT images reveal a spatial distribution of structures that appear to correspond with the MGs' acini and ducts (in healthy subjects), and accumulation of heterogeneous, highly scattering biological material and clear fluids in the visibly blocked glands. Noninvasive, volumetric high-resolution morphological imaging of the human tarsal area could have a significant impact in the clinical diagnosis of inflammatory and noninflammatory lid pathologies.

  16. Assessing vertebral fracture risk on volumetric quantitative computed tomography by geometric characterization of trabecular bone structure

    NASA Astrophysics Data System (ADS)

    Checefsky, Walter A.; Abidin, Anas Z.; Nagarajan, Mahesh B.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

    2016-03-01

    The current clinical standard for measuring Bone Mineral Density (BMD) is dual X-ray absorptiometry, however more recently BMD derived from volumetric quantitative computed tomography has been shown to demonstrate a high association with spinal fracture susceptibility. In this study, we propose a method of fracture risk assessment using structural properties of trabecular bone in spinal vertebrae. Experimental data was acquired via axial multi-detector CT (MDCT) from 12 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. Common image processing methods were used to annotate the trabecular compartment in the vertebral slices creating a circular region of interest (ROI) that excluded cortical bone for each slice. The pixels inside the ROI were converted to values indicative of BMD. High dimensional geometrical features were derived using the scaling index method (SIM) at different radii and scaling factors (SF). The mean BMD values within the ROI were then extracted and used in conjunction with a support vector machine to predict the failure load of the specimens. Prediction performance was measured using the root-mean-square error (RMSE) metric and determined that SIM combined with mean BMD features (RMSE = 0.82 +/- 0.37) outperformed MDCT-measured mean BMD (RMSE = 1.11 +/- 0.33) (p < 10-4). These results demonstrate that biomechanical strength prediction in vertebrae can be significantly improved through the use of SIM-derived texture features from trabecular bone.

  17. Influence of pore pressure change on coseismic volumetric strain

    NASA Astrophysics Data System (ADS)

    Wang, Chi-Yuen; Barbour, Andrew J.

    2017-10-01

    Coseismic strain is fundamentally important for understanding crustal response to changes of stress after earthquakes. The elastic dislocation model has been widely applied to interpreting observed shear deformation caused by earthquakes. The application of the same theory to interpreting volumetric strain, however, has met with difficulty, especially in the far field of earthquakes. Predicted volumetric strain with dislocation model often differs substantially, and sometimes of opposite signs, from observed coseismic volumetric strains. The disagreement suggests that some processes unaccounted for by the dislocation model may occur during earthquakes. Several hypotheses have been suggested, but none have been tested quantitatively. In this paper we first examine published data to highlight the difference between the measured and calculated static coseismic volumetric strains; we then use these data to provide quantitative test of the model that the disagreement may be explained by the change of pore pressure in the shallow crust. The test allows us to conclude that coseismic change of pore pressure may be an important mechanism for coseismic crustal strain and, in the far field, may even be the dominant mechanism. Thus in the interpretation of observed coseismic crustal strain, one needs to account not only for the elastic strain due to fault rupture but also for the strain due to coseismic change of pore pressure.

  18. Space-Time Transfinite Interpolation of Volumetric Material Properties.

    PubMed

    Sanchez, Mathieu; Fryazinov, Oleg; Adzhiev, Valery; Comninos, Peter; Pasko, Alexander

    2015-02-01

    The paper presents a novel technique based on extension of a general mathematical method of transfinite interpolation to solve an actual problem in the context of a heterogeneous volume modelling area. It deals with time-dependent changes to the volumetric material properties (material density, colour, and others) as a transformation of the volumetric material distributions in space-time accompanying geometric shape transformations such as metamorphosis. The main idea is to represent the geometry of both objects by scalar fields with distance properties, to establish in a higher-dimensional space a time gap during which the geometric transformation takes place, and to use these scalar fields to apply the new space-time transfinite interpolation to volumetric material attributes within this time gap. The proposed solution is analytical in its nature, does not require heavy numerical computations and can be used in real-time applications. Applications of this technique also include texturing and displacement mapping of time-variant surfaces, and parametric design of volumetric microstructures.

  19. Combination Gravimetric/Volumetric Sorption Instrument for Energy Applications

    NASA Astrophysics Data System (ADS)

    Bethea, Donald; Burress, Jacob

    The use of gaseous fuels such as hydrogen and methane (natural gas) will reduce emissions. Unfortunately, the storage of hydrogen and methane at room temperature is difficult because they are both supercritical gases, making the adoption of these fuels cumbersome. One means of overcoming the storage problem is to use physisorption-based systems which exploit the van der Waals interaction between the gas and a nanoporous material to compress the gases to near liquid densities. To measure the amount of gas in these materials, gravimetric or volumetric methods are employed. Gravimetric weighs the amount of gas and volumetric uses differences in gas pressures. Gravimetric systems typically have problems with buoyancy corrections. Volumetric systems normally have larger uncertainties that propagate through the isotherm. A modified system will be presented which allows for both gravimetric and volumetric gas sorption measurements. Additionally, the buoyancy corrections for the gravimetric measurements are significantly small and less than the uncertainties in the measurement. This apparatus can take measurements of most gases at room temperature and up to 200 bar.

  20. Skuller: A volumetric shape registration algorithm for modeling skull deformities.

    PubMed

    Sahillioğlu, Yusuf; Kavan, Ladislav

    2015-07-01

    We present an algorithm for volumetric registration of 3D solid shapes. In comparison to previous work on image based registration, our technique achieves higher efficiency by leveraging a template tetrahedral mesh. In contrast to point- and surface-based registration techniques, our method better captures volumetric nature of the data, such as bone thickness. We apply our algorithm to study pathological skull deformities caused by a particular condition, i.e., craniosynostosis. The input to our system is a pair of volumetric 3D shapes: a tetrahedral mesh and a voxelized object represented by a set of voxel cells segmented from computed tomography (CT) scans. Our general framework first performs a global registration and then launches a novel elastic registration process that uses as much volumetric information as possible while deforming the generic template tetrahedral mesh of a healthy human skull towards the underlying geometry of the voxel cells. Both data are high-resolution and differ by large non-rigid deformations. Our fully-automatic solution is fast and accurate, as compared with the state of the arts from the reconstruction and medical image registration fields. We use the resulting registration to match the ground-truth surfaces extracted from the medical data as well as to quantify the severity of the anatomical deformity.

  1. Video-rate volumetric optical coherence tomography-based microangiography

    NASA Astrophysics Data System (ADS)

    Baran, Utku; Wei, Wei; Xu, Jingjiang; Qi, Xiaoli; Davis, Wyatt O.; Wang, Ruikang K.

    2016-04-01

    Video-rate volumetric optical coherence tomography (vOCT) is relatively young in the field of OCT imaging but has great potential in biomedical applications. Due to the recent development of the MHz range swept laser sources, vOCT has started to gain attention in the community. Here, we report the first in vivo video-rate volumetric OCT-based microangiography (vOMAG) system by integrating an 18-kHz resonant microelectromechanical system (MEMS) mirror with a 1.6-MHz FDML swept source operating at ˜1.3 μm wavelength. Because the MEMS scanner can offer an effective B-frame rate of 36 kHz, we are able to engineer vOMAG with a video rate up to 25 Hz. This system was utilized for real-time volumetric in vivo visualization of cerebral microvasculature in mice. Moreover, we monitored the blood perfusion dynamics during stimulation within mouse ear in vivo. We also discussed this system's limitations. Prospective MEMS-enabled OCT probes with a real-time volumetric functional imaging capability can have a significant impact on endoscopic imaging and image-guided surgery applications.

  2. Uptake and Loss of Carbon Dioxide in Volumetric Analysis.

    ERIC Educational Resources Information Center

    Macca, Carlo

    1986-01-01

    Discusses the use of ratio diagrams, which plot the calculations of equilibrium concentrations of the species of the carbonate system. Provides examples to describe how these diagrams can be used to illustrate the behavior systems of interest in volumetric analysis, where absorption or loss of carbon dioxide takes place. (TW)

  3. VOLUMETRIC LEAK DETECTION IN LARGE UNDERGROUND STORAGE TANKS - VOLUME I

    EPA Science Inventory

    A set of experiments was conducted to determine whether volumetric leak detection system presently used to test underground storage tanks (USTs) up to 38,000 L (10,000 gal) in capacity could meet EPA's regulatory standards for tank tightness and automatic tank gauging systems whe...

  4. Anomalous transport and generalized axial charge

    NASA Astrophysics Data System (ADS)

    Kirilin, Vladimir P.; Sadofyev, Andrey V.

    2017-07-01

    In this paper we continue studying the modification of the axial charge in chiral media by macroscopic helicities. Recently it was shown that magnetic reconnections result in a persistent current of zero mode along flux tubes. Here we argue that in general a change in the helical part of the generalized axial charge results in the same phenomenon. Thus one may say that there is a novel realization of chiral effects requiring no initial chiral asymmetry. The transfer of flow helicity to zero modes is analyzed in a toy model based on a vortex reconnection in a chiral superfluid. Then, we discuss the balance between the two competing processes effect of reconnections and the chiral instability on the example of magnetic helicity. We argue that in the general case there is a possibility for the distribution of the axial charge between the magnetic and fermionic forms at the end of the instability.

  5. Organocatalytic atroposelective synthesis of axially chiral styrenes

    NASA Astrophysics Data System (ADS)

    Zheng, Sheng-Cai; Wu, San; Zhou, Qinghai; Chung, Lung Wa; Ye, Liu; Tan, Bin

    2017-05-01

    Axially chiral compounds are widespread in biologically active compounds and are useful chiral ligands or organocatalysts in asymmetric catalysis. It is well-known that styrenes are one of the most abundant and principal feedstocks and thus represent excellent prospective building blocks for chemical synthesis. Driven by the development of atroposelective synthesis of axially chiral styrene derivatives, we discovered herein the asymmetric organocatalytic approach via direct Michael addition reaction of substituted diones/ketone esters/malononitrile to alkynals. The axially chiral styrene compounds were produced with good chemical yields, enantioselectivities and almost complete E/Z-selectivities through a secondary amine-catalysed iminium activation strategy under mild conditions. Such structural motifs are important precursors for further transformations into biologically active compounds and synthetic useful intermediates and may have potential applications in asymmetric synthesis as olefin ligands or organocatalysts.

  6. Axial flow positive displacement worm gas generator

    NASA Technical Reports Server (NTRS)

    Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)

    2010-01-01

    An axial flow positive displacement engine has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first, second, and third sections of a core assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. The first twist slopes are less than the second twist slopes and the third twist slopes are less than the second twist slopes. A combustor section extends axially downstream through at least a portion of the second section.

  7. Visualization and computer graphics on isotropically emissive volumetric displays.

    PubMed

    Mora, Benjamin; Maciejewski, Ross; Chen, Min; Ebert, David S

    2009-01-01

    The availability of commodity volumetric displays provides ordinary users with a new means of visualizing 3D data. Many of these displays are in the class of isotropically emissive light devices, which are designed to directly illuminate voxels in a 3D frame buffer, producing X-ray-like visualizations. While this technology can offer intuitive insight into a 3D object, the visualizations are perceptually different from what a computer graphics or visualization system would render on a 2D screen. This paper formalizes rendering on isotropically emissive displays and introduces a novel technique that emulates traditional rendering effects on isotropically emissive volumetric displays, delivering results that are much closer to what is traditionally rendered on regular 2D screens. Such a technique can significantly broaden the capability and usage of isotropically emissive volumetric displays. Our method takes a 3D dataset or object as the input, creates an intermediate light field, and outputs a special 3D volume dataset called a lumi-volume. This lumi-volume encodes approximated rendering effects in a form suitable for display with accumulative integrals along unobtrusive rays. When a lumi-volume is fed directly into an isotropically emissive volumetric display, it creates a 3D visualization with surface shading effects that are familiar to the users. The key to this technique is an algorithm for creating a 3D lumi-volume from a 4D light field. In this paper, we discuss a number of technical issues, including transparency effects due to the dimension reduction and sampling rates for light fields and lumi-volumes. We show the effectiveness and usability of this technique with a selection of experimental results captured from an isotropically emissive volumetric display, and we demonstrate its potential capability and scalability with computer-simulated high-resolution results.

  8. Volumetric requirements for foam and mist drilling operations

    SciTech Connect

    Okpobiri, G.A.; Ikoku, C.U.

    1986-02-01

    State-of-the-art foam and mist drilling suggests a need for predictive models for volumetric requirements that properly account for frictional losses caused by the solid phase in solids/foam slurry flow, settling velocities of such solids, and pressure drop across bit nozzles during foam flow. The objective of this paper is to fulfill this need. A model that predicts pressure drop across bit nozzles for foam and mist and minimum volumetric requirements for foam and mist drilling operations is presented. It accounts for the compressibility of foam but assumes negligible pressure losses resulting from friction and change in elevation and for the frictional losses caused by the solid phase, pressure drop across bit nozzles, and particle-settling velocity. This technique offers a high degree of flexibility in the selection of wellhead injection pressures and volumetric injection rates. Field application of this work can be accomplished by two primarily graphical methods that depend on compressor specification: variable-backpressure and constant-backpressure schedules. Charts are presented for 7.875- and 9.00-in. hole sizes, and for 0.500-, 0.75-, and 1.00-in. cutting sizes. Penetration rates range from 30 to 90 ft/hr. Results indicate that volumetric requirements increase with increasing hole size, depth, and particle size. Increases in penetration rate cause only minor increases in volumetric requirements. All foam-drilling and well-cleanout operations can be accomplished within the laminar flow region with adherence to 0.55 minimum bottomhole and 0.96 maximum annular foam quality. Annular backpressures greater than atmospheric pressure are needed to maintain a bottomhole foam quality of 0.55 or more while reaching reasonable depths. To maintain constant depth as backpressure increases, however, both wellhead injection pressure and gas injection rate must be increased, and liquid flow rate decreased.

  9. Analysis of Changing Swarm Rate using Volumetric Strain

    NASA Astrophysics Data System (ADS)

    Kumazawa, T.; Ogata, Y.; Kimura, K.; Maeda, K.; Kobayashi, A.

    2015-12-01

    Near the eastern coast of Izu peninsula is an active submarine volcanic region in Japan, where magma intrusions have been observed many times. The forecast of earthquake swarm activities and eruptions are serious concern particularly in nearby hot spring resort areas. It is well known that temporal durations of the swarm activities have been correlated with early volumetric strain changes at a certain observation station of about 20 km distance apart. Therefore the Earthquake Research Committee (2010) investigated some empirical statistical relations to predict sizes of the swarm activity. Here we looked at the background seismicity rate changes during these swarm periods using the non-stationary ETAS model (Kumazawa and Ogata, 2013, 2014), and have found the followings. The modified volumetric strain data, by removing the effect of earth tides, precipitation and coseismic jumps, have significantly higher cross-correlations to the estimated background rates of the ETAS model than to the swarm rate-changes. Specifically, the background seismicity rate synchronizes clearer to the strain change by the lags around a half day. These relations suggest an enhanced prediction of earthquakes in this region using volumetric strain measurements. Hence we propose an extended ETAS model where the background rate is modulated by the volumetric strain data. We have also found that the response function to the strain data can be well approximated by an exponential functions with the same decay rate, but that their intersects are inversely proportional to the distances between the volumetric strain-meter and the onset location of the swarm. Our numerical results by the same proposed model show consistent outcomes for the various major swarms in this region.

  10. In vivo real-time volumetric synthetic aperture ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Bouzari, Hamed; Rasmussen, Morten F.; Brandt, Andreas H.; Stuart, Matthias B.; Nikolov, Svetoslav; Jensen, Jørgen A.

    2015-03-01

    Synthetic aperture (SA) imaging can be used to achieve real-time volumetric ultrasound imaging using 2-D array transducers. The sensitivity of SA imaging is improved by maximizing the acoustic output, but one must consider the limitations of an ultrasound system, both technical and biological. This paper investigates the in vivo applicability and sensitivity of volumetric SA imaging. Utilizing the transmit events to generate a set of virtual point sources, a frame rate of 25 Hz for a 90° × 90° field-of-view was achieved. data were obtained using a 3.5 MHz 32 × 32 elements 2-D phased array transducer connected to the experimental scanner (SARUS). Proper scaling is applied to the excitation signal such that intensity levels are in compliance with the U.S. Food and Drug Administration regulations for in vivo ultrasound imaging. The measured Mechanical Index and spatial-peak-temporal-average intensity for parallel beam-forming (PB) are 0.83 and 377.5mW/cm2, and for SA are 0.48 and 329.5mW/cm2. A human kidney was volumetrically imaged with SA and PB techniques simultaneously. Two radiologists for evaluation of the volumetric SA were consulted by means of a questionnaire on the level of details perceivable in the beam-formed images. The comparison was against PB based on the in vivo data. The feedback from the domain experts indicates that volumetric SA images internal body structures with a better contrast resolution compared to PB at all positions in the entire imaged volume. Furthermore, the autocovariance of a homogeneous area in the in vivo SA data, had 23.5% smaller width at the half of its maximum value compared to PB.

  11. Axial pico turbine - construction and experimental research

    NASA Astrophysics Data System (ADS)

    Peczkis, G.; Goryca, Z.; Korczak, A.

    2017-08-01

    The paper concerns axial water turbine of power equal to 1 kW. The example of axial water turbine constructional calculations was provided, as well as turbine rotor construction with NACA profile blades. The laboratory test rig designed and built to perform measurements on pico turbine was described. The turbine drove three-phase electrical generator. On the basis of highest efficiency parameters, pico turbine basic characteristics were elaborated. The experimental research results indicated that pico turbine can achieve maximum efficiency close to the values of larger water turbines.

  12. Rotor self-lubricating axial stop

    NASA Technical Reports Server (NTRS)

    Blount, Dale H. (Inventor)

    1989-01-01

    A plurality of lubricating plugs are disposed in the stationary backup face adjacent to the axial stop face of a rotating impeller mounted in a turbopump for pumping liquid oxygen or liquid hydrogen. The stop face and the backup face are those surfaces which engage when the axial load on the impeller exceeds the load balancing capability. The plugs have a truncated conical configuration so as to be trapped in the backup face, and are disposed at varying radii on the face to provide complete surface lubrication. The plugs may be formed from Teflon, Kel-F or bronze filled Teflon.

  13. A Mixed Finite Analysis of Axial Foreshortening

    NASA Technical Reports Server (NTRS)

    Ruzicka, Gene; Rutkowski, Michael (Technical Monitor)

    2000-01-01

    In previous studies, a mixed finite element was derived and shown to be effective in facilitating accurate modal reduction of rotor blades. This study builds upon that earlier work through the development of algorithms that allow the element's Lagrangian axial displacement degrees of freedom to be eliminated in favor of the axial force degrees of freedom. This reduction process, which had been demonstrated previously for the case of a single mixed finite element, may be viewed as a generalization of the UMARC blade analysis methodology to arbitrary topologies. A unique strength of the method. developed here is that the model may consist of two dimensional or even three dimensional elements.

  14. Rotor self-lubricating axial stop

    NASA Technical Reports Server (NTRS)

    Blount, Dale H.

    1988-01-01

    A series of lubricating plugs is located in the stationary backup face adjacent to the axial stop face of a rotating impeller mounted in a turbopump for pumping liquid oxygen or liquid hydrogen. The stop face and the backup face are those surfaces which engage when the axial load on the impeller exceeds the load balancing capability. The plugs have a truncated conical configuration so as to be trapped in the backup face, and are placed at varying radii on the face to provide complete surface lubrication. The plugs may be formed from Teflon, Kel-F or bronze filled Teflon.

  15. Theoretical Determination of Axial Fan Performance

    NASA Technical Reports Server (NTRS)

    Struve, E.

    1943-01-01

    The report presents a method for the computation of axial fan characteristics. The method is based on the assumption that the law of constancy of the circulation along the blade holds, approximately, for all fan conditions for which the blade elements operate at normal angles of attack (up to the stalling angles). Pressure head coefficient K(sub a) and power coefficient K(sub u) for the force components in the axial and tangential directions, respectively, and analogous to the lift and drag coefficients C(sub y) and C(sub x) are conveniently introduced.

  16. Co-axial, high energy gamma generator

    DOEpatents

    Reijonen, Jani Petteri; Gicquel, Frederic

    2011-08-16

    A gamma ray generator includes an ion source in a first chamber. A second chamber is configured co-axially around the first chamber at a lower second pressure. Co-axially arranged plasma apertures separate the two chambers and provide for restricted passage of ions and gas from the first to the second chamber. The second chamber is formed by a puller electrode having at least one long channel aperture to draw ions from the first chamber when the puller electrode is subject to an appropriate applied potential. A plurality of electrodes rings in the third chamber in third pressure co-axially surround the puller electrode and have at least one channel corresponding to the at least one puller electrode aperture and plasma aperture. The electrode rings increase the energy of the ions to a selected energy in stages in passing between successive pairs of the electrodes by application of an accelerating voltage to the successive pairs of accelerator electrodes. A target disposed co-axially around the plurality of electrodes receives the beam of accelerated ions, producing gamma rays.

  17. CONFOCAL MICROSCOPY SYSTEM PERFORMANCE: AXIAL RESOLUTION

    EPA Science Inventory

    Abstract

    Confocal Microscopy System Performance: Axial resolution.
    Robert M. Zucker, PhD

    Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Re...

  18. Computerized axial tomography: the normal EMI scan.

    PubMed Central

    Gawler, J; Bull, J D; Du Boulay, G H; Marshall, J

    1975-01-01

    Computerized axial tomography using the EMI scanner as a new method of using x-rays in diagnosis. The technique displays intracranial and orbital structures in the transverse plane. The appearances of normal EMI Scans are described and correlated with cerebral and orbital anatomy seen in transverse section. Images PMID:1081587

  19. Investigations on Experimental Impellers for Axial Blowers

    NASA Technical Reports Server (NTRS)

    Encke, W.

    1947-01-01

    A selection of measurements obtained on experimental impellers for axial blowers will be reported. In addition to characteristic curves plotted for low and for high peripheral velocities, proportions and blade sections for six different blower models and remarks on the design of blowers will be presented.

  20. CONFOCAL MICROSCOPY SYSTEM PERFORMANCE: AXIAL RESOLUTION

    EPA Science Inventory

    Abstract

    Confocal Microscopy System Performance: Axial resolution.
    Robert M. Zucker, PhD

    Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Re...

  1. Computer programs for axial flow compressor design

    NASA Technical Reports Server (NTRS)

    Carmody, R. H.; Creveling, H. F.

    1969-01-01

    Four computer programs examine effects of design parameters and indicate areas for research of multistage axial flow compressors. The programs provide information on velocity diagrams and stage-by-stage performance calculation, radial equilibrium of flow, radial distribution of total pressure, and off-design performance calculation.

  2. Aerodynamic Design of Axial Flow Compressors

    NASA Technical Reports Server (NTRS)

    Bullock, R. O. (Editor); Johnsen, I. A.

    1965-01-01

    An overview of 'Aerodynamic systems design of axial flow compressors' is presented. Numerous chapters cover topics such as compressor design, ptotential and viscous flow in two dimensional cascades, compressor stall and blade vibration, and compressor flow theory. Theoretical aspects of flow are also covered.

  3. Excitation modes in non-axial nuclei

    SciTech Connect

    Leviatan, A.; Ginnochio, J.N.

    1990-01-01

    Excitation modes of non-axial quadrupole shapes are investigated in the framework of interacting boson models. Both {gamma}-unstable and {gamma}-rigid nuclear shapes are considered for systems with one type of boson as well as with proton-neutron bosons. 6 refs.

  4. Active axial stress in mouse aorta.

    PubMed

    Agianniotis, A; Rachev, A; Stergiopulos, N

    2012-07-26

    The study verifies the development of active axial stress in the wall of mouse aorta over a range of physiological loads when the smooth muscle cells are stimulated to contract. The results obtained show that the active axial stress is virtually independent of the magnitude of pressure, but depends predominately on the longitudinal stretch ratio. The dependence is non-monotonic and is similar to the active stress-stretch dependence in the circumferential direction reported in the literature. The expression for the active axial stress fitted to the experimental data shows that the maximum active stress is developed at longitudinal stretch ratio 1.81, and 1.56 is the longitudinal stretch ratio below which the stimulation does not generate active stress. The study shows that the magnitude of active axial stress is smaller than the active circumferential stress. There is need for more experimental investigations on the active response of different types of arteries from different species and pathological conditions. The results of these studies can promote building of refined constrictive models in vascular rheology. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Axial spondyloarthritis: the heart of the matter.

    PubMed

    Gensler, Lianne S

    2015-06-01

    A variety of cardiovascular clinical manifestations have been described in patients with spondyloarthritis, especially in well-established ankylosing spondylitis. These include both structural heart disease, conduction defects and ischemic heart disease. The true prevalence of cardiovascular involvement in patients with axial spondyloarthritis, including non-radiographic disease needs to be further defined.

  6. Lenses axial space ray tracing measurement.

    PubMed

    Zhao, Weiqian; Sun, Ruoduan; Qiu, Lirong; Shi, Libo; Sha, Dingguo

    2010-02-15

    In order to achieve the precise measurement of the lenses axial space, a new lenses axial space ray tracing measurement (ASRTM) is proposed based on the geometrical theory of optical image. For an assembled lenses with the given radius of curvature r(n) and refractive index nn of every lens, ASRTM uses the annular laser differential confocal chromatography focusing technique (ADCFT) to achieve the precise focusing at the vertex position P(n) of its inner-and-outer spherical surface Sn and obtain the coordinate z(n) corresponding to the axial movement position of ASRTM objective, and then, uses the ray tracing facet iterative algorithm to precisely determine the vertex position P(n) of every spherical surface by these coordinates z(n), refractive index n(n) and spherical radius r(n), and thereby obtaining the lenses inner axial space d(n). The preliminary experimental results indicate that ASRTM has a relative measurement error of less than 0.02%.

  7. Stability of structural members under axial load

    NASA Technical Reports Server (NTRS)

    Lundquist, Eugene E

    1937-01-01

    The principles of the cross method of moment distribution are used to check the stability of structural members under axial load. A brief theoretical treatment of the subject, together with an illustrative problem, is included as well as a discussion of the reduced modulus at high stresses and a set of tables to aid in the solution of practical problems.

  8. Supersonic axial-flow fan flutter

    NASA Technical Reports Server (NTRS)

    Ramsey, John K.

    1988-01-01

    Lane's (1957) analytical formulation of the unsteady pressure distribution on an oscillating two-dimensional flat plate cascade in supersonic axial flow has been developed into a computer code. This unsteady aerodynamic code has shown good agreement with other published data. This code has also been incorporated into an existing aeroelastic code to analyze the NASA Lewis supersonic through-flow fan design.

  9. Axial type self-bearing motor for axial flow blood pump.

    PubMed

    Okada, Yohji; Masuzawa, Toru; Matsuda, Ken-Ichi; Ohmori, Kunihiro; Yamane, Takashi; Konishi, Yoshiaki; Fukahori, Shinya; Ueno, Satoshi; Kim, Seung-Jong

    2003-10-01

    An axial self-bearing motor is proposed which can drive an axial blood pump without physical contact. It is a functional combination of the bi-directional disc motor and the axial active magnetic bearing, where it actively controls single degree-of-freedom motion, while other motions such as lateral vibration are passively stable. For application to a blood pump, the proposed self-bearing motor has the advantages of simple structure and small size. Through the finite element method (FEM) analysis and the experimental test, its good feasibility is verified. Finally, the axial flow pump is fabricated using the developed magnetically suspended motor. The pump test is carried out and the results are discussed in detail.

  10. Noninvasive volumetric imaging and morphometry of the rodent retina with high-speed, ultrahigh-resolution optical coherence tomography.

    PubMed

    Srinivasan, Vivek J; Ko, Tony H; Wojtkowski, Maciej; Carvalho, Mariana; Clermont, Allen; Bursell, Sven-Erik; Song, Qin Hui; Lem, Janis; Duker, Jay S; Schuman, Joel S; Fujimoto, James G

    2006-12-01

    To demonstrate high-speed, ultrahigh-resolution optical coherence tomography (OCT) for noninvasive, in vivo, three-dimensional imaging of the retina in rat and mouse models. A high-speed, ultrahigh-resolution OCT system using spectral, or Fourier domain, detection has been developed for small animal retinal imaging. Imaging is performed with a contact lens and postobjective scanning. An axial image resolution of 2.8 mum is achieved with a spectrally broadband superluminescent diode light source with a bandwidth of approximately 150 nm at approximately 900-nm center wavelength. Imaging can be performed at 24,000 axial scans per second, which is approximately 100 times faster than previous ultrahigh-resolution OCT systems. High-definition and three-dimensional retinal imaging is performed in vivo in mouse and rat models. High-speed, ultrahigh-resolution OCT enabled high-definition, high transverse pixel density imaging of the murine retina and visualization of all major intraretinal layers. Raster scan protocols enabled three-dimensional volumetric imagingand comprehensive retinal segmentation algorithms allowed measurement of retinal layers. An OCT fundus image, akin to a fundus photograph was generated by axial summation of three-dimensional OCT data, thus enabling precise registration of OCT measurements to retinal fundus features. High-speed, ultrahigh-resolution OCT enables imaging of retinal architectural morphology in small animal models. OCT fundus images allow precise registration of OCT images and repeated measurements with respect to retinal fundus features. Three-dimensional OCT imaging enables visualization and quantification of retinal structure, which promises to allow repeated, noninvasive measurements to track disease progression, thereby reducing the need for killing the animal for histology. This capability can accelerate basic research studies in rats and mice and their translation into clinical patient care.

  11. Tidal Triggering and Statistical Patterns of Microseismicity at Axial Volcano on the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Bohnenstiehl, D. R.; Dziak, R. P.; Caplan-Auerbach, J.; Haxel, J. H.; Mann, M. E.; Pennington, C.; Weis, J.; Womack, N.; Levy, S.

    2015-12-01

    Tidal stress changes are known to modulate the timing of microearthquakes within many mid-ocean ridge volcanic systems. At Axial Volcano, located on the Juan de Fuca Ridge, earthquakes occur preferentially when volumetric extension peaks near times of low ocean tide. Autonomous ocean-bottom hydrophone (OBH, 2007-2011) and cabled ocean bottom seismometer (OBS, Nov. 2014-) data are used to quantify the strength of tidal triggering in time periods before the April 2011 and April 2015 eruptions at Axial Volcano. The mean percent excess at times of low ocean-tide is ~14% (16% std) in the four years prior to the 2011 eruption and ~18% (17% std) in the five months prior to the 2015 eruption. The sensitivity of earthquakes to tidal stress does not evolve systematically prior to either eruption; however, this pattern is disturbed by much larger stress changes associated with the onset of dike intrusion. Following dike injection and eruption, seismicity rates drop sharply. As seismicity rates continue to rise in the months following the 2015 eruption, real-time data available from the cabled OBS network will be used quantify temporal patterns in microearthquake activity as dike induced stresses are relaxed and the magma chamber inflates.

  12. Pulse sequence for dynamic volumetric imaging of hyperpolarized metabolic products

    NASA Astrophysics Data System (ADS)

    Cunningham, Charles H.; Chen, Albert P.; Lustig, Michael; Hargreaves, Brian A.; Lupo, Janine; Xu, Duan; Kurhanewicz, John; Hurd, Ralph E.; Pauly, John M.; Nelson, Sarah J.; Vigneron, Daniel B.

    2008-07-01

    Dynamic nuclear polarization and dissolution of a 13C-labeled substrate enables the dynamic imaging of cellular metabolism. Spectroscopic information is typically acquired, making the acquisition of dynamic volumetric data a challenge. To enable rapid volumetric imaging, a spectral-spatial excitation pulse was designed to excite a single line of the carbon spectrum. With only a single resonance present in the signal, an echo-planar readout trajectory could be used to resolve spatial information, giving full volume coverage of 32 × 32 × 16 voxels every 3.5 s. This high frame rate was used to measure the different lactate dynamics in different tissues in a normal rat model and a mouse model of prostate cancer.

  13. Volumetric characterization of delamination fields via angle longitudinal wave ultrasound

    NASA Astrophysics Data System (ADS)

    Wertz, John; Wallentine, Sarah; Welter, John; Dierken, Josiah; Aldrin, John

    2017-02-01

    The volumetric characterization of delaminations necessarily precedes rigorous composite damage progression modeling. Yet, inspection of composite structures for subsurface damage remains largely focused on detection, resulting in a capability gap. In response to this need, angle longitudinal wave ultrasound was employed to characterize a composite surrogate containing a simulated three-dimensional delamination field with distinct regions of occluded features (shadow regions). Simple analytical models of the specimen were developed to guide subsequent experimentation through identification of optimal scanning parameters. The ensuing experiments provided visual evidence of the complete delamination field, including indications of features within the shadow regions. The results of this study demonstrate proof-of-principle for the use of angle longitudinal wave ultrasonic inspection for volumetric characterization of three-dimensional delamination fields. Furthermore, the techniques developed herein form the foundation of succeeding efforts to characterize impact delaminations within inhomogeneous laminar materials such as polymer matrix composites.

  14. Volumetric hydrogen storage in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, C.; Yang, Q. H.; Tong, Y.; Cong, H. T.; Cheng, H. M.

    2002-04-01

    Macroscopically long ropes of aligned single-walled carbon nanotubes (SWNTs), synthesized by a hydrogen and argon arc discharge method, were cold pressed into tablets without any binder for measurements of their volumetric hydrogen storage capacity. The typical apparent density of the tablets was measured to be around 1.7 g/cm3 with respect to a molding pressure of 0.75 Gpa. A volumetric and mass hydrogen storage capacity of 68 kg H2/m3 and 4.0 wt %, respectively, was achieved at room temperature under a pressure of 11 MPa for suitably pretreated SWNT tablets, and more than 70% of the hydrogen adsorbed can be released under ambient pressure at room temperature. Pore structure analysis indicated that the molding process diminished the mesopore volume of the SWNT ropes, but exerts little influence on their intrinsic pore textures.

  15. COMPARISON OF VOLUMETRIC REGISTRATION ALGORITHMS FOR TENSOR-BASED MORPHOMETRY

    PubMed Central

    Villalon, Julio; Joshi, Anand A.; Toga, Arthur W.; Thompson, Paul M.

    2015-01-01

    Nonlinear registration of brain MRI scans is often used to quantify morphological differences associated with disease or genetic factors. Recently, surface-guided fully 3D volumetric registrations have been developed that combine intensity-guided volume registrations with cortical surface constraints. In this paper, we compare one such algorithm to two popular high-dimensional volumetric registration methods: large-deformation viscous fluid registration, formulated in a Riemannian framework, and the diffeomorphic “Demons” algorithm. We performed an objective morphometric comparison, by using a large MRI dataset from 340 young adult twin subjects to examine 3D patterns of correlations in anatomical volumes. Surface-constrained volume registration gave greater effect sizes for detecting morphometric associations near the cortex, while the other two approaches gave greater effects sizes subcortically. These findings suggest novel ways to combine the advantages of multiple methods in the future. PMID:26925198

  16. Volumetric chemical imaging by stimulated Raman projection microscopy and tomography

    PubMed Central

    Chen, Xueli; Zhang, Chi; Lin, Peng; Huang, Kai-Chih; Liang, Jimin; Tian, Jie; Cheng, Ji-Xin

    2017-01-01

    Volumetric imaging allows global understanding of three-dimensional (3D) complex systems. Light-sheet fluorescence microscopy and optical projection tomography have been reported to image 3D volumes with high resolutions and at high speeds. Such methods, however, usually rely on fluorescent labels for chemical targeting, which could perturb the biological functionality in living systems. We demonstrate Bessel-beam-based stimulated Raman projection (SRP) microscopy and tomography for label-free volumetric chemical imaging. Our SRP microscope enables fast quantitation of chemicals in a 3D volume through a two-dimensional lateral scan. Furthermore, combining SRP and sample rotation, we demonstrate the SRP tomography that can reconstruct the 3D distribution of chemical compositions with optical spatial resolution at a higher speed than the Gaussian-beam-based stimulated Raman scattering sectioning imaging can. We explore the potential of our SRP technology by mapping polymer particles in 3D volumes and lipid droplets in adipose cells. PMID:28436473

  17. Volumetric chemical imaging by stimulated Raman projection microscopy and tomography

    NASA Astrophysics Data System (ADS)

    Chen, Xueli; Zhang, Chi; Lin, Peng; Huang, Kai-Chih; Liang, Jimin; Tian, Jie; Cheng, Ji-Xin

    2017-04-01

    Volumetric imaging allows global understanding of three-dimensional (3D) complex systems. Light-sheet fluorescence microscopy and optical projection tomography have been reported to image 3D volumes with high resolutions and at high speeds. Such methods, however, usually rely on fluorescent labels for chemical targeting, which could perturb the biological functionality in living systems. We demonstrate Bessel-beam-based stimulated Raman projection (SRP) microscopy and tomography for label-free volumetric chemical imaging. Our SRP microscope enables fast quantitation of chemicals in a 3D volume through a two-dimensional lateral scan. Furthermore, combining SRP and sample rotation, we demonstrate the SRP tomography that can reconstruct the 3D distribution of chemical compositions with optical spatial resolution at a higher speed than the Gaussian-beam-based stimulated Raman scattering sectioning imaging can. We explore the potential of our SRP technology by mapping polymer particles in 3D volumes and lipid droplets in adipose cells.

  18. High volumetric power density, non-enzymatic, glucose fuel cells.

    PubMed

    Oncescu, Vlad; Erickson, David

    2013-01-01

    The development of new implantable medical devices has been limited in the past by slow advances in lithium battery technology. Non-enzymatic glucose fuel cells are promising replacement candidates for lithium batteries because of good long-term stability and adequate power density. The devices developed to date however use an "oxygen depletion design" whereby the electrodes are stacked on top of each other leading to low volumetric power density and complicated fabrication protocols. Here we have developed a novel single-layer fuel cell with good performance (2 μW cm⁻²) and stability that can be integrated directly as a coating layer on large implantable devices, or stacked to obtain a high volumetric power density (over 16 μW cm⁻³). This represents the first demonstration of a low volume non-enzymatic fuel cell stack with high power density, greatly increasing the range of applications for non-enzymatic glucose fuel cells.

  19. Pulse Sequence for Dynamic Volumetric Imaging of Hyperpolarized Metabolic Products

    PubMed Central

    Cunningham, Charles H.; Chen, Albert P.; Lustig, Michael; Lupo, Janine; Xu, Duan; Kurhanewicz, John; Hurd, Ralph E.; Pauly, John M.; Nelson, Sarah J.; Vigneron, Daniel B.

    2011-01-01

    Dynamic nuclear polarization and dissolution of a 13C-labeled substrate enables the dynamic imaging of cellular metabolism. Spectroscopic information is typically acquired, making the acquisition of dynamic volumetric data a challenge. To enable rapid volumetric imaging, a spectral-spatial excitation pulse was designed to excite a single line of the carbon spectrum. With only a single resonance present in the signal, an echo-planar readout trajectory could be used to resolve spatial information, giving full volume coverage of 32 × 32 × 16 voxels every 3.5 seconds. This high frame rate was used to measure the different lactate dynamics in different tissues in a normal rat model and a mouse model of prostate cancer. PMID:18424203

  20. Normative segment-specific axial and coronal angulation corridors of subaxial cervical column in axial rotation.

    PubMed

    Yoganandan, Narayan; Stemper, Brian D; Pintar, Frank A; Baisden, Jamie L; Shender, Barry S; Paskoff, Glenn

    2008-03-01

    In contrast to clinical studies wherein loading magnitudes are indeterminate, experiments permit controlled and quantifiable moment applications, record kinematics in multiple planes, and allow derivation of moment-angulation corridors. Axial and coronal moment-angulation corridors were determined at every level of the subaxial cervical spine, expressed as logarithmic functions, and level-specificity of range of motion and neutral zones were evaluated. segmental primary axial and coupled coronal motions do not vary by level. Although it is known that cervical spine responses are coupled, segment-specific corridors of axial and coronal kinematics under axial twisting moments from healthy normal spines are not reported. Ten human cadaver columns (23-44 years, mean: 34 +/- 6.8) were fixed at the ends and targets were inserted to each vertebra to obtain kinematics in axial and coronal planes. The columns were subjected to pure axial twisting moments. Range of motion and neutral zone for primary-axial and coupled-coronal rotation components were determined at each spinal level. Data were analyzed using factorial analysis of variance. Moment-rotation angulations were expressed using logarithmic functions, and mean +/-1 standard deviation corridors were derived at each level for both components. Moment-angulations responses were nonlinear. Each segmental curve for both components was well represented by a logarithmic function (r2 > 0.95). Factorial analysis of variance indicated that the biomechanical metrics are spinal level-specific (P < 0.05). Axial and coronal angulations of cervical spinal columns show statistically different level-specific responses. The presentation of moment-angulation corridors for both metrics forms a dataset for the normal population. These segment-specific nonlinear corridors may help clinicians assess dysfunction or instability. These data will assist mathematical models of the spine in improved validation and lead to efficacious design of

  1. Description of Axial Detail for ROK Fuel

    SciTech Connect

    Trellue, Holly R; Galloway, Jack D

    2012-04-20

    For the purpose of NDA simulations of the ROK fuel assemblies, we have developed an axial burnup distribution to represent the pins themselves based on gamma scans of rods in the G23 assembly. For the purpose of modeling the G23 assembly (both at ORNL and LANL), the pin-by-pin burnup map as simulated by ROK is being assumed to represent the radial burnup distribution. However, both DA and NDA results indicate that this simulated estimate is not 100% correct. In particular, the burnup obtained from the axial gamma scan of 7 pins does not represent exactly the same 'average' pin burnup as the ROK simulation. Correction for this discrepancy is a goal of the well-characterized assembly task but will take time. For now, I have come up with a correlation for 26 axial points of the burnup as obtained by gamma scans of 7 different rods (C13, G01, G02, J11, K10, L02, and M04, neglecting K02 at this time) to the average burnup given by the simulation for each of the rods individually. The resulting fraction in each axial zone is then averaged for the 7 different rods so that it can represent every fuel pin in the assembly. The burnup in each of the 26 axial zones of rods in all ROK assemblies will then be directly adjusted using this fraction, which is given in Table 1. Note that the gamma scan data given by ROK for assembly G23 included a length of {approx}3686 mm, so the first 12 mm and the last 14 mm were ignored to give an actual rod length of {approx}366 cm. To represent assembly F02 in which no pin-by-pin burnup distribution is given by ROK, we must model it using infinitely-reflected geometry but can look at the effects of measuring in different axial zones by using intermediate burnup files (i.e. smaller burnups than 28 GWd/MTU) and determining which axial zone(s) each burnup represents. Details for assembly F02 are then given in Tables 2 and 3, which is given in Table 1 and has 44 total axial zones to represent the top meter in explicit detail in addition to the

  2. Volumetric 3D display using a DLP projection engine

    NASA Astrophysics Data System (ADS)

    Geng, Jason

    2012-03-01

    In this article, we describe a volumetric 3D display system based on the high speed DLPTM (Digital Light Processing) projection engine. Existing two-dimensional (2D) flat screen displays often lead to ambiguity and confusion in high-dimensional data/graphics presentation due to lack of true depth cues. Even with the help of powerful 3D rendering software, three-dimensional (3D) objects displayed on a 2D flat screen may still fail to provide spatial relationship or depth information correctly and effectively. Essentially, 2D displays have to rely upon capability of human brain to piece together a 3D representation from 2D images. Despite the impressive mental capability of human visual system, its visual perception is not reliable if certain depth cues are missing. In contrast, volumetric 3D display technologies to be discussed in this article are capable of displaying 3D volumetric images in true 3D space. Each "voxel" on a 3D image (analogous to a pixel in 2D image) locates physically at the spatial position where it is supposed to be, and emits light from that position toward omni-directions to form a real 3D image in 3D space. Such a volumetric 3D display provides both physiological depth cues and psychological depth cues to human visual system to truthfully perceive 3D objects. It yields a realistic spatial representation of 3D objects and simplifies our understanding to the complexity of 3D objects and spatial relationship among them.

  3. Inorganic volumetric light source excited by ultraviolet light

    DOEpatents

    Reed, S.; Walko, R.J.; Ashley, C.S.; Brinker, C.J.

    1994-04-26

    The invention relates to a composition for the volumetric generation of radiation. The composition comprises a porous substrate loaded with a component capable of emitting radiation upon interaction with an exciting radiation. Preferably, the composition is an aerogel substrate loaded with a component, e.g., a phosphor, capable of interacting with exciting radiation of a first energy, e.g., ultraviolet light, to produce radiation of a second energy, e.g., visible light. 4 figures.

  4. Inorganic volumetric light source excited by ultraviolet light

    DOEpatents

    Reed, Scott; Walko, Robert J.; Ashley, Carol S.; Brinker, C. Jeffrey

    1994-01-01

    The invention relates to a composition for the volumetric generation of radiation. The composition comprises a porous substrate loaded with a component capable of emitting radiation upon interaction with an exciting radiation. Preferably, the composition is an aerogel substrate loaded with a component, e.g., a phosphor, capable of interacting with exciting radiation of a first energy, e.g., ultraviolet light, to produce radiation of a second energy, e.g., visible light.

  5. Determining the volumetric steam content in a BWR gravity leg

    SciTech Connect

    Fedulin, V.N.; Bartolomei, G.G.; Solodkii, V.A.; Shmelev, V.E.

    1987-09-01

    The structure of two-phase flow in a large-diameter limited-height gravity leg was investigated in the VK-50 reactor. Phase distribution properties and a physical model of the steam-water mixture flow in the gravity leg were described. On the basis of experimentally derived date a method was proposed for the calculation of volumetric steam content in the leg.

  6. Volumetric Light-field Encryption at the Microscopic Scale

    NASA Astrophysics Data System (ADS)

    Li, Haoyu; Guo, Changliang; Muniraj, Inbarasan; Schroeder, Bryce C.; Sheridan, John T.; Jia, Shu

    2017-01-01

    We report a light-field based method that allows the optical encryption of three-dimensional (3D) volumetric information at the microscopic scale in a single 2D light-field image. The system consists of a microlens array and an array of random phase/amplitude masks. The method utilizes a wave optics model to account for the dominant diffraction effect at this new scale, and the system point-spread function (PSF) serves as the key for encryption and decryption. We successfully developed and demonstrated a deconvolution algorithm to retrieve both spatially multiplexed discrete data and continuous volumetric data from 2D light-field images. Showing that the method is practical for data transmission and storage, we obtained a faithful reconstruction of the 3D volumetric information from a digital copy of the encrypted light-field image. The method represents a new level of optical encryption, paving the way for broad industrial and biomedical applications in processing and securing 3D data at the microscopic scale.

  7. Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV)

    NASA Astrophysics Data System (ADS)

    Falahatpisheh, Ahmad; Kheradvar, Arash

    2015-11-01

    Measurement of 3D flow field inside the cardiac chambers has proven to be a challenging task. Current laser-based 3D PIV methods estimate the third component of the velocity rather than directly measuring it and also cannot be used to image the opaque heart chambers. Modern echocardiography systems are equipped with 3D probes that enable imaging the entire 3D opaque field. However, this feature has not yet been employed for 3D vector characterization of blood flow. For the first time, we introduce a method that generates velocity vector field in 4D based on volumetric echocardiographic images. By assuming the conservation of brightness in 3D, blood speckles are tracked. A hierarchical 3D PIV method is used to account for large particle displacement. The discretized brightness transport equation is solved in a least square sense in interrogation windows of size 163 voxels. We successfully validate the method in analytical and experimental cases. Volumetric echo data of a left ventricle is then processed in the systolic phase. The expected velocity fields were successfully predicted by V-Echo-PIV. In this work, we showed a method to image blood flow in 3D based on volumetric images of human heart using no contrast agent.

  8. Volumetric Light-field Encryption at the Microscopic Scale

    PubMed Central

    Li, Haoyu; Guo, Changliang; Muniraj, Inbarasan; Schroeder, Bryce C.; Sheridan, John T.; Jia, Shu

    2017-01-01

    We report a light-field based method that allows the optical encryption of three-dimensional (3D) volumetric information at the microscopic scale in a single 2D light-field image. The system consists of a microlens array and an array of random phase/amplitude masks. The method utilizes a wave optics model to account for the dominant diffraction effect at this new scale, and the system point-spread function (PSF) serves as the key for encryption and decryption. We successfully developed and demonstrated a deconvolution algorithm to retrieve both spatially multiplexed discrete data and continuous volumetric data from 2D light-field images. Showing that the method is practical for data transmission and storage, we obtained a faithful reconstruction of the 3D volumetric information from a digital copy of the encrypted light-field image. The method represents a new level of optical encryption, paving the way for broad industrial and biomedical applications in processing and securing 3D data at the microscopic scale. PMID:28059149

  9. Innovative system architecture for spatial volumetric acoustic seeing

    NASA Astrophysics Data System (ADS)

    Levin, Eugene; Sergeyev, Aleksandr V.

    2009-04-01

    Situational awareness is a critical issue for the modern battle and security systems improvement of which will increase human performance efficiency. There are multiple research project and development efforts based on omni-directional (fish-eye) electro-optical and other frequency sensor fusion systems implementing head-mounted visualization systems. However, the efficiency of these systems is limited by the human eye-brain system perception limitations. Humans are capable to naturally perceive the situations in front of them, but interpretation of omni-directional visual scenes increases the user's mental workload, increasing human fatigue and disorientation requiring more effort for object recognition. It is especially important to reduce this workload making rear scenes perception intuitive in battlefield situations where a combatant can be attacked from both directions. This paper describes an experimental model of the system fusion architecture of the Visual Acoustic Seeing (VAS) for representation spatial geometric 3D model in form of 3D volumetric sound. Current research in the area of auralization points to the possibility of identifying sound direction. However, for complete spatial perception it is necessary to identify the direction and the distance to an object by an expression of volumetric sound, we initially assume that the distance can be encoded by the sound frequency. The chain: object features -> sensor -> 3D geometric model-> auralization constitutes Volumetric Acoustic Seeing (VAS). Paper describes VAS experimental research for representing and perceiving spatial information by means of human hearing cues in more details.

  10. Volumetric requirements for foam and mist drilling operations

    SciTech Connect

    Okpobiri, G.A.; Ikoku, C.U.

    1983-03-01

    The present state of the art in foam and mist drilling suggests a need for predictive models for volumetric requirements that properly account for frictional losses due to the solid phase in solidsfoam slurry flow, settling velocities of such solids, and pressure drop across bit nozzles during foam flow. The objective of this paper is to fulfill this need. A model for predicting pressure drop across bit nozzles for foam and mist is presented. It accounts for the compressibility of foam, but assumes negligible pressure losses due to friction and change in elevation. A model has been developed for predicting minimum volumetric requirements for foam and mist drilling operations. It accounts for the frictional losses due to the solid phase, pressure drop across bit nozzles, and particle settling velocity. The technique offers a high degree of flexibility in the selection of wellhead injection pressures and volumetric injection rates. Field application of this work can be accomplished by two methods depending on compressor specifications. These are the ''variable back pressure'' and ''constant back pressure'' schedules. These are primarily graphical. Charts are presented for 7.875 and 9.00-inch hole sizes, and cuttings sizes of 0.500, 0.75, and 1.00 inch. Penetration rates range from 30 to 90 ft/hr.

  11. A volumetric three-dimensional digital light photoactivatable dye display

    NASA Astrophysics Data System (ADS)

    Patel, Shreya K.; Cao, Jian; Lippert, Alexander R.

    2017-07-01

    Volumetric three-dimensional displays offer spatially accurate representations of images with a 360° view, but have been difficult to implement due to complex fabrication requirements. Herein, a chemically enabled volumetric 3D digital light photoactivatable dye display (3D Light PAD) is reported. The operating principle relies on photoactivatable dyes that become reversibly fluorescent upon illumination with ultraviolet light. Proper tuning of kinetics and emission wavelengths enables the generation of a spatial pattern of fluorescent emission at the intersection of two structured light beams. A first-generation 3D Light PAD was fabricated using the photoactivatable dye N-phenyl spirolactam rhodamine B, a commercial picoprojector, an ultraviolet projector and a custom quartz imaging chamber. The system displays a minimum voxel size of 0.68 mm3, 200 μm resolution and good stability over repeated `on-off' cycles. A range of high-resolution 3D images and animations can be projected, setting the foundation for widely accessible volumetric 3D displays.

  12. A volumetric three-dimensional digital light photoactivatable dye display

    PubMed Central

    Patel, Shreya K.; Cao, Jian; Lippert, Alexander R.

    2017-01-01

    Volumetric three-dimensional displays offer spatially accurate representations of images with a 360° view, but have been difficult to implement due to complex fabrication requirements. Herein, a chemically enabled volumetric 3D digital light photoactivatable dye display (3D Light PAD) is reported. The operating principle relies on photoactivatable dyes that become reversibly fluorescent upon illumination with ultraviolet light. Proper tuning of kinetics and emission wavelengths enables the generation of a spatial pattern of fluorescent emission at the intersection of two structured light beams. A first-generation 3D Light PAD was fabricated using the photoactivatable dye N-phenyl spirolactam rhodamine B, a commercial picoprojector, an ultraviolet projector and a custom quartz imaging chamber. The system displays a minimum voxel size of 0.68 mm3, 200 μm resolution and good stability over repeated ‘on-off’ cycles. A range of high-resolution 3D images and animations can be projected, setting the foundation for widely accessible volumetric 3D displays. PMID:28695887

  13. Reducing uncertainties in volumetric image based deformable organ registration.

    PubMed

    Liang, J; Yan, D

    2003-08-01

    Applying volumetric image feedback in radiotherapy requires image based deformable organ registration. The foundation of this registration is the ability of tracking subvolume displacement in organs of interest. Subvolume displacement can be calculated by applying biomechanics model and the finite element method to human organs manifested on the multiple volumetric images. The calculation accuracy, however, is highly dependent on the determination of the corresponding organ boundary points. Lacking sufficient information for such determination, uncertainties are inevitable-thus diminishing the registration accuracy. In this paper, a method of consuming energy minimization was developed to reduce these uncertainties. Starting from an initial selection of organ boundary point correspondence on volumetric image sets, the subvolume displacement and stress distribution of the whole organ are calculated and the consumed energy due to the subvolume displacements is computed accordingly. The corresponding positions of the initially selected boundary points are then iteratively optimized to minimize the consuming energy under geometry and stress constraints. In this study, a rectal wall delineated from patient CT image was artificially deformed using a computer simulation and utilized to test the optimization. Subvolume displacements calculated based on the optimized boundary point correspondence were compared to the true displacements, and the calculation accuracy was thereby evaluated. Results demonstrate that a significant improvement on the accuracy of the deformable organ registration can be achieved by applying the consuming energy minimization in the organ deformation calculation.

  14. Volumetric dimensional change of six direct core materials.

    PubMed

    Chutinan, Supattriya; Platt, Jeffrey A; Cochran, Michael A; Moore, B Keith

    2004-05-01

    This study evaluated the influence of water on the volumetric dimensional change of six direct placement core build-up materials by using Archimedes' principle. The effect on dimensional change due to the setting reaction was determined through the use of a silicone oil storage medium. The materials used were two dual-cured resin composites (CoreStore and Build-It FR), two chemically activated resin composites (CorePaste and Ti-Core), one metal-reinforced glass ionomer cement (Ketac-Silver), and one resin-modified glass ionomer (Fuji II LC Core). Using the manufacturers' instructions for each material, cylindrical specimens were prepared with dimensions of 7+/-0.1 mm in diameter and 2+/-0.1 mm in height. Each material had four groups (n = 5) based on storage conditions; silicone oil at 23 and 37 degrees C and distilled water at 23 and 37 degrees C. A 0.01 mg resolution balance was used to determine volumetric dimensional change using an Archimedean equation. Measurements were made 30 min after mixing, and at the time intervals of 1, 14, and 56 days. All materials exhibited dimensional change. Ketac-Silver had the most shrinkage in silicone oil and Fuji II LC showed the highest expansion in distilled water. The glass ionomer materials showed more change than did any of the resin composite materials. Current direct placement core materials show variation in the amount of volumetric dimensional change seen over a period of 56 days.

  15. Quality Multi-domain Meshing for Volumetric Data

    PubMed Central

    Zhang, Qin; Subramanian, Bharadwaj; Xu, Guoliang; Bajaj, Chandrajit L.

    2011-01-01

    Multi-domain meshing from volumetric data is of great importance in many fields like medicine, biology and geology. This paper proposes a new approach to produce a high quality mesh with separated multiple domains. A point cloud is generated from a preliminary mesh representing the boundary between different domains from the discrete volumetric representation used as input. A higher-order level-set method is employed to produce a quality sub-mesh from this point cloud and geometric flow is used as smoothing mechanism. A new approach to detect and curate intersections within an assembly of these 2-manifold sub-meshes by utilizing the intermediate volumetric representation is developed. The separation between sub-meshes can be controlled by the user using a gap threshold parameter. The resulting high quality multi-domain mesh is free from self- and inter-domain intersections and can be further utilized in finite element and boundary element computations. The proposed pipeline has been efficiently implemented and sample meshes have been provided for visualization. PMID:21544233

  16. Volumetric Light-field Encryption at the Microscopic Scale.

    PubMed

    Li, Haoyu; Guo, Changliang; Muniraj, Inbarasan; Schroeder, Bryce C; Sheridan, John T; Jia, Shu

    2017-01-06

    We report a light-field based method that allows the optical encryption of three-dimensional (3D) volumetric information at the microscopic scale in a single 2D light-field image. The system consists of a microlens array and an array of random phase/amplitude masks. The method utilizes a wave optics model to account for the dominant diffraction effect at this new scale, and the system point-spread function (PSF) serves as the key for encryption and decryption. We successfully developed and demonstrated a deconvolution algorithm to retrieve both spatially multiplexed discrete data and continuous volumetric data from 2D light-field images. Showing that the method is practical for data transmission and storage, we obtained a faithful reconstruction of the 3D volumetric information from a digital copy of the encrypted light-field image. The method represents a new level of optical encryption, paving the way for broad industrial and biomedical applications in processing and securing 3D data at the microscopic scale.

  17. Volumetric characterization of sodium-induced G-quadruplex formation.

    PubMed

    Fan, Helen Y; Shek, Yuen Lai; Amiri, Amir; Dubins, David N; Heerklotz, Heiko; Macgregor, Robert B; Chalikian, Tigran V

    2011-03-30

    Oligodeoxyribonucleotides (ODN) with repeats of the human telomeric sequence can adopt different tetrahelical conformations that exhibit similar energetic parameters. We studied the volumetric properties of the folded and unfolded states of an ODN with four repeats of the human telomeric sequence, d[A(GGGTTA)(3)GGG], by combining pressure-perturbation calorimetry (PPC), vibrating tube densimetry, ultrasonic velocimetry, and UV melting under high pressure. We carried out our volumetric measurements in aqueous buffers at pH 7 containing 20, 50, and 100 mM NaCl. All of the methods employed yielded volumetric parameters that were in excellent agreement. The molar volume changes, ΔV, of the conformational transition leading to formation of the folded state are large and positive. At 50 mM NaCl, the average transition volume, ΔV(tr), obtained from all the methods is 56.4 ± 3.5 cm(3) mol(-1) at the transition temperature of 47 °C, with ΔV(tr) decreasing with an increase in temperature. We carried out a molecular dynamics simulation of the change in the intrinsic geometric parameters of the ODN accompanying quadruplex formation. On the basis of the experimental and computational results, the folding transition of the ODN is accompanied by a release of 103 ± 44 water molecules from its hydration shell to the bulk. This number corresponds to ~18% of the net hydration of the coil conformation.

  18. Volumetric lattice Boltzmann simulation for blood flow in aorta arteries

    NASA Astrophysics Data System (ADS)

    Deep, Debanjan; Yu, Huidan (Whitney); Teague, Shawn

    2012-11-01

    Complicated moving boundaries pose a major challenge in computational fluid dynamics for complex flows, especially in the biomechanics of both blood flow in the cardiovascular system and air flow in the respiratory system where the compliant nature of the vessels can have significant effects on the flow rate and wall shear stress. We develop a computation approach to treat arbitrarily moving boundaries using a volumetric representation of lattice Boltzmann method, which distributes fluid particles inside lattice cells. A volumetric bounce-back procedure is applied in the streaming step while momentum exchange between the fluid and moving solid boundary are accounted for in the collision sub-step. Additional boundary-induced migration is introduced to conserve fluid mass as the boundary moves across fluid cells. The volumetric LBM (VLBM) is used to simulate blood flow in both normal and dilated aorta arteries. We first compare flow structure and pressure distribution in steady state with results from Navier-Stokes based solver and good agreements are achieved. Then we focus on wall stress within the aorta for different heart pumping condition and present quantitative measurement of wall shear and normal stress.

  19. Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations

    SciTech Connect

    Wagner, J.C.; DeHart, M.D.

    2000-03-01

    This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ``end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified.

  20. Piping inspection carriage having axially displaceable sensor

    DOEpatents

    Zollinger, W.T.; Treanor, R.C.

    1994-12-06

    A pipe inspection instrument carriage is described for use with a pipe crawler for performing internal inspections of piping surfaces. The carriage has a front leg assembly, a rear leg assembly and a central support connecting the two assemblies and for mounting an instrument arm having inspection instruments. The instrument arm has a Y-arm mounted distally thereon for axially aligning the inspection instrumentation and a mounting block, a linear actuator and axial movement arm for extending the inspection instruments radially outward to operably position the inspection instruments on the piping interior. Also, the carriage has a rotation motor and gear assembly for rotating the central support and the front leg assembly with respect to the rear leg assembly so that the inspection instruments azimuthally scan the piping interior. The instrument carriage allows performance of all piping inspection operations with a minimum of moving parts, thus decreasing the likelihood of performance failure. 4 figures.

  1. Piping inspection carriage having axially displaceable sensor

    DOEpatents

    Zollinger, William T.; Treanor, Richard C.

    1994-01-01

    A pipe inspection instrument carriage for use with a pipe crawler for performing internal inspections of piping surfaces. The carriage has a front leg assembly, a rear leg assembly and a central support connecting the two assemblies and for mounting an instrument arm having inspection instruments. The instrument arm has a y-arm mounted distally thereon for axially aligning the inspection instrumentation and a mounting block, a linear actuator and axial movement arm for extending the inspection instruments radially outward to operably position the inspection instruments on the piping interior. Also, the carriage has a rotation motor and gear assembly for rotating the central support and the front leg assembly with respect to the rear leg assembly so that the inspection instruments azimuthally scan the piping interior. The instrument carriage allows performance of all piping inspection operations with a minimum of moving parts, thus decreasing the likelihood of performance failure.

  2. Axial flow positive displacement worm compressor

    NASA Technical Reports Server (NTRS)

    Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)

    2010-01-01

    An axial flow positive displacement compressor has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first and second sections of a compressor assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first and second twist slopes in the first and second sections respectively. The first twist slopes are less than the second twist slopes. An engine including the compressor has in downstream serial flow relationship from the compressor a combustor and a high pressure turbine drivingly connected to the compressor by a high pressure shaft.

  3. Buckling of axially compressed conical shells

    NASA Technical Reports Server (NTRS)

    Chang, C.-H.; Katz, L.

    1980-01-01

    The buckling of a truncated elastic conical shell subjected to an axial compression is a classical problem in shell structures. The paper reinvestigates the buckling of an axially compressed truncated conical shell with rigid bulkheads. Two improvements are achieved. First, the condition that the total horizontal displacement must vanish due to rigid bulkhead and axisymmetry is treated as a constraint. This constraint is incorporated into the system through the use of the Lagrange multiplier; then the variational method is used to derive a complete set of boundary conditions for conical shells. Second, the stability is evaluated in the deformed state using the asymptotic solutions of the pair of Donnell-type equations for axisymmetric configuration. The results indicate that the buckling strength of conical shells depends mainly on the condition of the smaller end. In addition to the vertex angle, the distance ratio plays, at least, an equally important role.

  4. Tri-axial tactile sensing element

    NASA Astrophysics Data System (ADS)

    Castellanos-Ramos, Julián.; Navas-González, Rafael; Vidal-Verdú, F.

    2013-05-01

    A 13 x 13 square millimetre tri-axial taxel is presented which is suitable for some medical applications, for instance in assistive robotics that involves contact with humans or in prosthetics. Finite Element Analysis is carried out to determine what structure is the best to obtain a uniform distribution of pressure on the sensing areas underneath the structure. This structure has been fabricated in plastic with a 3D printer and a commercial tactile sensor has been used to implement the sensing areas. A three axis linear motorized translation stage with a tri-axial precision force sensor is used to find the parameters of the linear regression model and characterize the proposed taxel. The results are analysed to see to what extent the goal has been reached in this specific implementation.

  5. Micrometer axial resolution OCT for corneal imaging

    PubMed Central

    Yadav, Rahul; Lee, Kye-Sung; Rolland, Jannick P.; Zavislan, James M.; Aquavella, James V.; Yoon, Geunyoung

    2011-01-01

    An optical coherence tomography (OCT) for high axial resolution corneal imaging is presented. The system uses 375 nm bandwidth (625 to 1000 nm) from a broadband supercontinuum light source. The system was developed in free space to minimize image quality degradation due to dispersion. A custom-designed spectrometer based on a Czerny Turner configuration was implemented to achieve an imaging depth of 1 mm. Experimentally measured axial resolution was 1.1 μm in corneal tissue and had a good agreement with the theoretically calculated resolution from the envelope of the spectral interference fringes. In vivo imaging was carried out and thin corneal layers such as the tear film and the Bowman’s layer were quantified in normal, keratoconus, and contact lens wearing eyes, indicating the system’s suitability for several ophthalmic applications. PMID:22076265

  6. The closed co-axial analgesia system.

    PubMed

    Waaben, J; Jørgensen, S; Oxhøj, H; Arnsbo, P

    1980-10-01

    A twin-tube system for nitrous oxide analgesia in dental surgeries is described. The system is a non-polluting modification of the Mapleson A system, employing the principle of co-axial tubing introduced by Bain & Spoerel (1972). Active, continuous and calibrated gas removal takes place via the co-axial tubing by means of an ejector flowmeter. Investigation of the dynamic pressure excursions occurring at the nose-piece are fully compatible with normal breathing. Gas contamination of the dental environment can be reduced by at least 90%. The system described is safe and easy to handle. It is made of light-weight material and is adaptable to the equipment available. No rebreathing takes place when using a fresh gas inflow of 150 ml/kg body weight/min.

  7. Axial length changes after retinal detachment surgery.

    PubMed

    Burton, T C; Herron, B E; Ossoinig, K C

    1977-01-01

    A-scan echography was an accurate method for detecting changes in the depth of the anterior chamber, lens thickness, and length of the vitreous cavity after retinal detachment surgery in 30 eyes. Approximately 60% of the eyes had significant alterations in axial lengths exceeding+/-0.36 mm in aphakic eyes and +/-0.54 mm in phakic eyes. However, the operation of scleral bucklingg with large segments of hard silicone rubber implants or explants supported by an encircling band failed to result in a significant predictable shift of axial change in phakic or aphakic eyes. A-scan echography showed significant shallowing of the anterior chamber, and scleral buckling significantly increases lens thickness for at least six weeks. This induced a minor myopic refractive change that may explain some of the difference in postoperative refracitons between phakic and aphakic eyes.

  8. Microwave axial dielectric properties of carbon fiber

    PubMed Central

    Hong, Wen; Xiao, Peng; Luo, Heng; Li, Zhuan

    2015-01-01

    Randomly distributed carbon fibers (CFs) reinforced epoxy resin composites are prepared by the pouring method, the dielectric properties of CF composites with different fiber content and length have been performed in the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the composite increases with the fiber length, which is attributed to the decrease of depolarization field, and increases with the volume fraction, which is attributed to the increase of polarization. A formula, based on the theory of Reynolds-Hugh, is proposed to calculate the effective permittivity of CF composites, and validated by the experiments. The proposed formula is further applied to derive the axial permittivity of CF and analyze the effect of fiber length on the axial permittivity. PMID:26477579

  9. Modular organization of axial microcircuits in zebrafish

    PubMed Central

    Bagnall, Martha W.; McLean, David L.

    2014-01-01

    Locomotion requires precise control of spinal networks. In tetrapods and bipeds, dynamic regulation of locomotion is simplified by the modular organization of spinal limb circuits, but it is not known whether their predecessors, fish axial circuits, are similarly organized. Here, we demonstrate that the larval zebrafish spinal cord contains distinct, parallel microcircuits for independent control of dorsal and ventral musculature on each side of the body. During normal swimming, dorsal and ventral microcircuits are equally active; but during postural correction, fish differentially engage these microcircuits to generate torque for self-righting. These findings reveal greater complexity in the axial spinal networks responsible for swimming than previously recognized and suggest an early template of modular organization for more complex locomotor circuits in later vertebrates. PMID:24408436

  10. Computed tomography of axial skeletal osteoid osteomas

    SciTech Connect

    Gamba, J.L.; Martinez, S.; Apple, J.; Harrelson, J.M.; Nunley, J.A.

    1984-04-01

    Five cases of axial skeletal osteoid osteomas were viewed with particular attention to the role of computed tomography (CT) as a key diagnostic tool in the evaluation of osteoid osteoma. The complex anatomy of the axial skeleton can make the diagnosis of osteoid osteoma extremely difficult on routine films or tomograms, and the lesion often is well delineated only on CT scans. As complete surgical excision of this benign bony tumor is curative, precise anatomic localization is essential to the surgeon. Conventional radiographs were normal in all patients. Bone scans were positive when obtained and were useful in localizing the lesion and directing CT to the appropriate level. In all five cases CT was of proven value in accurately demonstrating the location, nidus, and other characteristic diagnostic radiographic features of osteoid osteoma.

  11. Innovations of wide-field optical-sectioning fluorescence microscopy: toward high-speed volumetric bio-imaging with simplicity

    NASA Astrophysics Data System (ADS)

    Yu, Jiun-Yann

    result in certain degrees of photo-damages because of the high focal intensity at the scanning point. In order to overcome such an issue, several wide-field optical-sectioning techniques have been proposed and demonstrated, although not without introducing new limitations and compromises such as low signal-to-background ratios and reduced axial resolutions. As a result, single-point-scanning optical-sectioning techniques remain the most widely used instrumentations for volumetric imaging of living biological systems to date. In order to develop wide-field optical-sectioning techniques that has equivalent optical performance as single-point-scanning ones, this thesis first introduces the mechanisms and limitations of existing wide-field optical-sectioning techniques, and then brings in our innovations that aim to overcome these limitations. We demonstrate, theoretically and experimentally, that our proposed wide-field optical-sectioning techniques can achieve diffraction-limited optical sectioning, low out-of-focus excitation and high-frame-rate imaging in living biological systems. In addition to such imaging capabilities, our proposed techniques can be instrumentally simple and economic, and are straightforward for implementation on conventional wide-field microscopes. These advantages together show the potential of our innovations to be widely used for high-speed, volumetric fluorescence imaging of living biological systems.

  12. Measurement of axial forces via natural frequency

    NASA Astrophysics Data System (ADS)

    Petro, Samer H.; Reynolds, Don; EnChen, Shen; GangaRao, Hota V. S.

    1998-03-01

    This paper presents results from testing several suspender ropes of the Delaware Memorial Bridge using vibration measurements and a non-destructive evaluation (NDE) instrument called the Axial Load Monitor (ALM). The testing consisted of measuring the frequencies of suspender ropes and determining their tension levels. Results were compared to theoretical predictions. This paper presents the results of the testing and discusses the problems associated with vibration measurements on actual bridges.

  13. Atlanto-axial subluxation: a case report

    PubMed Central

    Thurlow, Robert D

    1988-01-01

    One of the causes of death in rheumatoid patients is cord compression following atlanto-axial subluxation. Dislocations in the cervical spine are common with patients who have rheumatoid arthritis. Anterior subluxation occurs in up to 35%, followed by vertical subluxation in 22.2%, lateral subluxation in 20.6% and rarely posterior subluxation. A case report is presented to illustrate such a complication. ImagesFigure 1Figure 2Figure 3Figure 4

  14. Compressive strength of axially loaded composite cylinders

    NASA Astrophysics Data System (ADS)

    Kollar, Laszlo P.; Springer, George C.; Spingarn, Jay; McColskey, J. D.

    1993-10-01

    Tests were performed to measure the failure loads of axially compressed glass-fiber-reinforced and graphite-fiber-reinforced composite cylinders. The data were compared with the results of a previous model, which was based on a three-dimensional stress analysis and the Tsai-Wu quadratic first-ply failure criterion. This model predicted the failure loads for glass-fiber-reinforced composites with good accuracy, but less accurately for failure loads of graphite-epoxy composites.

  15. Bessel beam CARS of axially structured samples

    PubMed Central

    Heuke, Sandro; Zheng, Juanjuan; Akimov, Denis; Heintzmann, Rainer; Schmitt, Michael; Popp, Jürgen

    2015-01-01

    We report about a Bessel beam CARS approach for axial profiling of multi-layer structures. This study presents an experimental implementation for the generation of CARS by Bessel beam excitation using only passive optical elements. Furthermore, an analytical expression is provided describing the generated anti-Stokes field by a homogeneous sample. Based on the concept of coherent transfer functions, the underling resolving power of axially structured geometries is investigated. It is found that through the non-linearity of the CARS process in combination with the folded illumination geometry continuous phase-matching is achieved starting from homogeneous samples up to spatial sample frequencies at twice of the pumping electric field wave. The experimental and analytical findings are modeled by the implementation of the Debye Integral and scalar Green function approach. Finally, the goal of reconstructing an axially layered sample is demonstrated on the basis of the numerically simulated modulus and phase of the anti-Stokes far-field radiation pattern. PMID:26046671

  16. Wetting on axially-patterned heterogeneous surfaces.

    PubMed

    Rodríguez-Valverde, M A; Ruiz-Cabello, F J Montes; Cabrerizo-Vilchez, M A

    2008-05-19

    Contact angle variability, leading to errors in interpretation, arises from various sources. Contact angle hysteresis (history-dependent wetting) and contact angle multiplicity (corrugation of three-phase contact line) are irrespectively the most frequent causes of this uncertainty. Secondary effects also derived from the distribution of chemical defects on solid surfaces, and so due to the existence of boundaries, are the known "stick/jump-slip" phenomena. Currently, the underlying mechanisms in contact angle hysteresis and their connection to "stick/jump-slip" effects and the prediction of thermodynamic contact angle are not fully understood. In this study, axial models of smooth heterogeneous surface were chosen in order to mitigate contact angle multiplicity. For each axial pattern, advancing, receding and equilibrium contact angles were predicted from the local minima location of the system free energy. A heuristic model, based on the local Young equation for spherical drops on patch-wise axial patterns, was fruitfully tested from the results of free-energy minimization. Despite the very simplistic surface model chosen in this study, it allowed clarifying concepts usually misleading in wetting phenomena.

  17. Direct optical nanoscopy with axially localized detection

    NASA Astrophysics Data System (ADS)

    Bourg, N.; Mayet, C.; Dupuis, G.; Barroca, T.; Bon, P.; Lécart, S.; Fort, E.; Lévêque-Fort, S.

    2015-09-01

    Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Here, we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called supercritical-angle fluorescence can be captured using a high-numerical-aperture objective and used to determine the axial position of the fluorophore with nanometre precision. We introduce a new technique for three-dimensional nanoscopy that combines direct stochastic optical reconstruction microscopy (dSTORM) with dedicated detection of supercritical-angle fluorescence emission. We demonstrate that our approach of direct optical nanoscopy with axially localized detection (DONALD) typically yields an isotropic three-dimensional localization precision of 20 nm within an axial range of ∼150 nm above the coverslip.

  18. Bessel beam CARS of axially structured samples.

    PubMed

    Heuke, Sandro; Zheng, Juanjuan; Akimov, Denis; Heintzmann, Rainer; Schmitt, Michael; Popp, Jürgen

    2015-06-05

    We report about a Bessel beam CARS approach for axial profiling of multi-layer structures. This study presents an experimental implementation for the generation of CARS by Bessel beam excitation using only passive optical elements. Furthermore, an analytical expression is provided describing the generated anti-Stokes field by a homogeneous sample. Based on the concept of coherent transfer functions, the underling resolving power of axially structured geometries is investigated. It is found that through the non-linearity of the CARS process in combination with the folded illumination geometry continuous phase-matching is achieved starting from homogeneous samples up to spatial sample frequencies at twice of the pumping electric field wave. The experimental and analytical findings are modeled by the implementation of the Debye Integral and scalar Green function approach. Finally, the goal of reconstructing an axially layered sample is demonstrated on the basis of the numerically simulated modulus and phase of the anti-Stokes far-field radiation pattern.

  19. Bessel beam CARS of axially structured samples

    NASA Astrophysics Data System (ADS)

    Heuke, Sandro; Zheng, Juanjuan; Akimov, Denis; Heintzmann, Rainer; Schmitt, Michael; Popp, Jürgen

    2015-06-01

    We report about a Bessel beam CARS approach for axial profiling of multi-layer structures. This study presents an experimental implementation for the generation of CARS by Bessel beam excitation using only passive optical elements. Furthermore, an analytical expression is provided describing the generated anti-Stokes field by a homogeneous sample. Based on the concept of coherent transfer functions, the underling resolving power of axially structured geometries is investigated. It is found that through the non-linearity of the CARS process in combination with the folded illumination geometry continuous phase-matching is achieved starting from homogeneous samples up to spatial sample frequencies at twice of the pumping electric field wave. The experimental and analytical findings are modeled by the implementation of the Debye Integral and scalar Green function approach. Finally, the goal of reconstructing an axially layered sample is demonstrated on the basis of the numerically simulated modulus and phase of the anti-Stokes far-field radiation pattern.

  20. Axial gravity, massless fermions and trace anomalies

    NASA Astrophysics Data System (ADS)

    Bonora, L.; Cvitan, M.; Prester, P. Dominis; Pereira, A. Duarte; Giaccari, S.; Štemberga, T.

    2017-08-01

    This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones.

  1. Vibration of axially loaded circular arches

    SciTech Connect

    Sabir, A.B.; Djoudi, M.S.

    1996-11-01

    The work in the present paper is devoted to the determination of the buckling loads and natural frequencies of axially loaded arch structures. The finite element method is employed using a strain based arch element. The element is based on the conventional Euler curved beam type of strain displacement relationship and satisfies the exact representation of rigid body modes. The sub-space iteration technique is used to determine the eigenvalues and corresponding eigenvectors of the governing transcendental equation. The buckling of a pinned arch subjected to a uniform lateral pressure is first considered. The work is then extended to produce a comprehensive set of results for the vibration of axially loaded arches which are either pinned or fixed at both ends. The first symmetric and anti symmetric modes of vibration are determined and the effect of the axial load on these frequencies is investigated. The practical problem of an arch with a backfill is then considered and the effect of the elastic packing due to this backfill on the natural frequencies is determined.

  2. Golimumab for the treatment of axial spondyloarthritis.

    PubMed

    Gelfer, Gita; Perry, Lisa; Deodhar, Atul

    2016-01-01

    Axial spondyloarthritis (axSpA) is a chronic, immune-mediated inflammatory disease of the axial skeleton that includes ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (nr-axSpA). Patients with AS experience chronic pain due to sacroiliac joint and spinal inflammation, and may develop spinal ankylosing with syndesmophyte formation. Tumor necrosis factor α inhibitors (TNFi) have shown promise in the management of AS and axSpA by targeting the underlying inflammatory process, and providing symptomatic relief. Whether they alter the progression of the disease is uncertain. Golimumab is a fully human IgG1 monoclonal antibody that targets and downregulates the pro-inflammatory cytokine TNF-α. The use of golimumab has been shown to reduce the signs and symptoms of axSpA as well as improve patient function and quality reported outcomes. This review focuses on the biological rationale and the results of clinical trials with golimumab for the treatment of axSpA.

  3. Turbulence Effects of Axial Flow Hydrokinetic Turbines

    NASA Astrophysics Data System (ADS)

    Hill, C.; Chamorro, L. P.; Neary, V. S.; Morton, S.; Sotiropoulos, F.

    2011-12-01

    Axial flow hydrokinetic turbines provide a method for extracting the kinetic energy available in unidirectional (river), bidirectional (tidal) and marine currents; however, a deep understanding of the wake dynamics, momentum recovery, geomorphologic effects, and ecological interaction with these hydrokinetic turbines is required to guarantee their economical and environmental viability. The St. Anthony Falls Laboratory (SAFL) at the University of Minnesota (UMN) has performed physical modeling experiments using a 1:10 scale axial flow tidal turbine in the SAFL Main Channel, a 2.75m x 1.8m x 80m open channel test facility. A sophisticated control system allows synchronous measurements of turbine torque and rotational speed along with high resolution 3-D velocity measurements within the channel. Using acoustic Doppler velocimeters (ADVs), high resolution 3-D velocity profile data were collected up to 15 turbine diameters downstream of the turbine location. These data provide valuable information on the wake characteristics (turbulence, Reynolds stresses, etc.) resulting from a rotating axial flow hydrokinetic machine. Regions of high turbulence and shear zones that persist in the near wake regions are delineated along with the velocity deficit and momentum recovery within the wake downstream of the device. Synchronous ADV data shed light on the rotational and meandering characteristics of the wake and its potential impacts on the local geomorphology and hydrodynamic environment. This dataset on single hydrokinetic turbine flow characteristics is the basis for further work on the optimal arrangement and performance environment for arrays of similar hydrokinetic devices.

  4. Might axial myofascial properties and biomechanical mechanisms be relevant to ankylosing spondylitis and axial spondyloarthritis?

    PubMed

    Masi, Alfonse T

    2014-01-01

    Ankylosing spondylitis and axial spondyloarthropathy have characteristic age- and sex-specific onset patterns, typical entheseal lesions, and marked heritability, but the integrative mechanisms causing the pathophysiological and structural alterations remain largely undefined. Myofascial tissues are integrated in the body into webs and networks which permit transmission of passive and active tensional forces that provide stabilizing support and help to control movements. Axial myofascial hypertonicity was hypothesized as a potential excessive polymorphic trait which could contribute to chronic biomechanical overloading and exaggerated stresses at entheseal sites. Such a mechanism may help to integrate many of the characteristic host, pathological, and structural features of ankylosing spondylitis and axial spondyloarthritis. Biomechanical stress and strain were recently documented to correlate with peripheral entheseal inflammation and new bone formation in a murine model of spondyloarthritis. Ankylosing spondylitis has traditionally been classified by the modified New York criteria, which require the presence of definite radiographic sacroiliac joint lesions. New classification criteria for axial spondyloarthritis now include patients who do not fulfill the modified New York criteria. The male-to-female sex ratios clearly differed between the two patient categories - 2:1 or 3:1 in ankylosing spondylitis and 1:1 in non-radiographic axial spondyloarthritis - and this suggests a spectral concept of disease and, among females, milder structural alterations. Magnetic resonance imaging of active and chronic lesions in ankylosing spondylitis and axial spondyloarthritis reveals complex patterns, usually interpreted as inflammatory reactions, but shows similarities to acute degenerative disc disease, which attributed to edema formation following mechanical stresses and micro-damage. A basic question is whether mechanically induced microinjury and immunologically mediated

  5. Might axial myofascial properties and biomechanical mechanisms be relevant to ankylosing spondylitis and axial spondyloarthritis?

    PubMed Central

    2014-01-01

    Ankylosing spondylitis and axial spondyloarthropathy have characteristic age- and sex-specific onset patterns, typical entheseal lesions, and marked heritability, but the integrative mechanisms causing the pathophysiological and structural alterations remain largely undefined. Myofascial tissues are integrated in the body into webs and networks which permit transmission of passive and active tensional forces that provide stabilizing support and help to control movements. Axial myofascial hypertonicity was hypothesized as a potential excessive polymorphic trait which could contribute to chronic biomechanical overloading and exaggerated stresses at entheseal sites. Such a mechanism may help to integrate many of the characteristic host, pathological, and structural features of ankylosing spondylitis and axial spondyloarthritis. Biomechanical stress and strain were recently documented to correlate with peripheral entheseal inflammation and new bone formation in a murine model of spondyloarthritis. Ankylosing spondylitis has traditionally been classified by the modified New York criteria, which require the presence of definite radiographic sacroiliac joint lesions. New classification criteria for axial spondyloarthritis now include patients who do not fulfill the modified New York criteria. The male-to-female sex ratios clearly differed between the two patient categories - 2:1 or 3:1 in ankylosing spondylitis and 1:1 in non-radiographic axial spondyloarthritis - and this suggests a spectral concept of disease and, among females, milder structural alterations. Magnetic resonance imaging of active and chronic lesions in ankylosing spondylitis and axial spondyloarthritis reveals complex patterns, usually interpreted as inflammatory reactions, but shows similarities to acute degenerative disc disease, which attributed to edema formation following mechanical stresses and micro-damage. A basic question is whether mechanically induced microinjury and immunologically mediated

  6. Structural effects of radiation-induced volumetric expansion on unreinforced concrete biological shields

    DOE PAGES

    Le Pape, Y.

    2015-11-22

    Limited literature (Pomaro et al., 2011, Mirhosseini et al., 2014, Salomoni et al., 2014 and Andreev and Kapliy, 2014) is available on the structural analysis of irradiated concrete biological shield (CBS), although extended operations of nuclear powers plants may lead to critical neutron exposure above 1.0 × 10+19 n cm₋2. To the notable exception of Andreev and Kapliy, available structural models do not account for radiation-induced volumetric expansion, although it was found to develop important linear dimensional change of the order of 1%, and, can lead to significant concrete damage (Le Pape et al., 2015). A 1D-cylindrical model of an unreinforced CBS accounting for temperature and irradiation effects is developed. Irradiated concrete properties are characterized probabilistically using the updated database collected by Oak Ridge National Laboratory (Field et al., 2015). The overstressed concrete ratio (OCR) of the CBS, i.e., the proportion of the wall thickness being subject to stresses beyond the resistance of concrete, is derived by deterministic and probabilistic analysis assuming that irradiated concrete behaves as an elastic materials. In the bi-axial compressive zone near the reactor cavity, the OCR is limited to 5.7%, i.e., 8.6 cm (3more » $$_2^1$$ in.), whereas, in the tension zone, the OCR extends to 72%, i.e., 1.08 m (42$$_2^1$$ in.). Finally, we find that these results, valid for a maximum neutron fluence on the concrete surface of 3.1 × 10+19 n cm₋2 (E > 0.1 MeV) and, obtained after 80 years of operation, give an indication of the potential detrimental effects of prolonged irradiation of concrete in nuclear power plants.« less

  7. Oregon inlet: Hydrodynamics, volumetric flux and implications for larval fish transport

    SciTech Connect

    Nichols, C.R.; Pietrafesa, L.J.

    1997-05-01

    The temporal response of Oregon Inlet currents to atmospheric forcing and sea level fluctuations is analyzed using time and frequency domain analysis. Temporally persistent and spatially extensive ebb and flood events are identified using data sets from both within and outside of Oregon Inlet. Prism estimates are made to generate a time series of volumetric flux of water transported through the inlet. Water masses flooding into the Pamlico Sound via Oregon Inlet are identified in temperature (T) and salinity (S) space to determine their source of origin. Correlations are examined between the atmospheric wind field, the main axial slope of the inlet`s water level, inlet flow and T, S properties. Synoptic scale atmospheric wind events are found to dramatically and directly affect the transport of water towards (away from) the inlet on the ocean side, in concert with the contemporaneous transport away from (towards) the inlet on the estuary side, and a subsequent flooding into (out of) the estuary via Oregon Inlet. Thus, while astronomical tidal flooding and ebbing events are shown to be one-sided as coastal waters either set-up or set-down, synoptic scale wind events are shown to be manifested as a two-sided in-phase response set-up and set-down inside and outside the inlet, and thus are extremely effective in driving currents through the inlet. These subinertial frequency flood events are believed to be essential for both the recruitment and subsequent retention of estuarine dependent larval fish from the coastal ocean into Pamlico Sound. Year class strength of these finish may be determined annually by the relative strength and timing of these climatological wind events.

  8. Characterizing trabecular bone structure for assessing vertebral fracture risk on volumetric quantitative computed tomography

    NASA Astrophysics Data System (ADS)

    Nagarajan, Mahesh B.; Checefsky, Walter A.; Abidin, Anas Z.; Tsai, Halley; Wang, Xixi; Hobbs, Susan K.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

    2015-03-01

    While the proximal femur is preferred for measuring bone mineral density (BMD) in fracture risk estimation, the introduction of volumetric quantitative computed tomography has revealed stronger associations between BMD and spinal fracture status. In this study, we propose to capture properties of trabecular bone structure in spinal vertebrae with advanced second-order statistical features for purposes of fracture risk assessment. For this purpose, axial multi-detector CT (MDCT) images were acquired from 28 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. A semi-automated method was used to annotate the trabecular compartment in the central vertebral slice with a circular region of interest (ROI) to exclude cortical bone; pixels within were converted to values indicative of BMD. Six second-order statistical features derived from gray-level co-occurrence matrices (GLCM) and the mean BMD within the ROI were then extracted and used in conjunction with a generalized radial basis functions (GRBF) neural network to predict the failure load of the specimens; true failure load was measured through biomechanical testing. Prediction performance was evaluated with a root-mean-square error (RMSE) metric. The best prediction performance was observed with GLCM feature `correlation' (RMSE = 1.02 ± 0.18), which significantly outperformed all other GLCM features (p < 0.01). GLCM feature correlation also significantly outperformed MDCTmeasured mean BMD (RMSE = 1.11 ± 0.17) (p< 10-4). These results suggest that biomechanical strength prediction in spinal vertebrae can be significantly improved through characterization of trabecular bone structure with GLCM-derived texture features.

  9. Volumetrics of the caudate nucleus: reliability and validity of a new manual tracing protocol.

    PubMed

    Looi, Jeffrey Chee Leong; Lindberg, Olof; Liberg, Benny; Tatham, Vanessa; Kumar, Rajeev; Maller, Jerome; Millard, Ellen; Sachdev, Perminder; Högberg, Göran; Pagani, Marco; Botes, Lisa; Engman, Eva-Lena; Zhang, Yi; Svensson, Leif; Wahlund, Lars-Olof

    2008-08-30

    Our aim was to develop a reliable and valid manual segmentation protocol for tracing the caudate nucleus in MRI for volumetric and, potentially, shape analysis of the caudate. Using the protocol, two inter- and intra-rater reliability studies were conducted using five different raters on two different image analysis platforms (ANALYZE, Mayo Biomedical Imaging Resource, Rochester MN, USA, and HERMES, Nuclear Diagnostics AB, Stockholm, Sweden). Reference images for the detailed protocol are described. Two studies were performed. In study 1, the intra-rater class correlation ICC(1,1) for an experienced rater (JCLL) using this protocol for caudate nucleus volumes was evaluated by repeating right and left caudate measurements on 10 scans (20 comparisons) and was 0.972. The inter-rater class correlation ICC(1,k) with OL was 0.922 on 5 scans (10 comparisons) and with BL was 0.960 on 5 scans (10 comparisons). In study 2, VT obtained an intra-rater class correlation of 0.9 on 5 scans (involving 10 comparisons, e.g. right and left caudate). The inter-rater class correlation ICC(1,k) was 0.988 on 5 scans (again involving 10 comparisons) with EM. We therefore developed a novel, reliable and reference image-based, method of outlining the caudate nucleus on axial MRI scans, usable in two different image analysis laboratories, across two different sets number of tracers reliably, and across software platforms. This method is therefore potentially usable for any image analysis package capable of displaying and measuring outlined voxels from MRI brain scans.

  10. Structural effects of radiation-induced volumetric expansion on unreinforced concrete biological shields

    SciTech Connect

    Le Pape, Y.

    2015-11-22

    Limited literature (Pomaro et al., 2011, Mirhosseini et al., 2014, Salomoni et al., 2014 and Andreev and Kapliy, 2014) is available on the structural analysis of irradiated concrete biological shield (CBS), although extended operations of nuclear powers plants may lead to critical neutron exposure above 1.0 × 10+19 n cm₋2. To the notable exception of Andreev and Kapliy, available structural models do not account for radiation-induced volumetric expansion, although it was found to develop important linear dimensional change of the order of 1%, and, can lead to significant concrete damage (Le Pape et al., 2015). A 1D-cylindrical model of an unreinforced CBS accounting for temperature and irradiation effects is developed. Irradiated concrete properties are characterized probabilistically using the updated database collected by Oak Ridge National Laboratory (Field et al., 2015). The overstressed concrete ratio (OCR) of the CBS, i.e., the proportion of the wall thickness being subject to stresses beyond the resistance of concrete, is derived by deterministic and probabilistic analysis assuming that irradiated concrete behaves as an elastic materials. In the bi-axial compressive zone near the reactor cavity, the OCR is limited to 5.7%, i.e., 8.6 cm (3$_2^1$ in.), whereas, in the tension zone, the OCR extends to 72%, i.e., 1.08 m (42$_2^1$ in.). Finally, we find that these results, valid for a maximum neutron fluence on the concrete surface of 3.1 × 10+19 n cm₋2 (E > 0.1 MeV) and, obtained after 80 years of operation, give an indication of the potential detrimental effects of prolonged irradiation of concrete in nuclear power plants.

  11. Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

    DOEpatents

    Koplow, Jeffrey P.

    2016-02-16

    Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.

  12. Co-axial multicusp source for low axial energy spread ion beam production

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Gough, R. A.; Leung, K. N.; Vujic, J.; Williams, M. D.; Zahir, N.

    1999-09-01

    A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projets.

  13. Volumetric response of intracranial meningioma after photon or particle irradiation.

    PubMed

    Mozes, Petra; Dittmar, Jan Oliver; Habermehl, Daniel; Tonndorf-Martini, Eric; Hideghety, Katalin; Dittmar, Anne; Debus, Jürgen; Combs, Stephanie E

    2017-03-01

    Meningiomas are usually slow growing, well circumscribed intracranial tumors. In symptom-free cases observation with close follow-up imaging could be performed. Symptomatic meningiomas could be surgically removed and/or treated with radiotherapy. The study aimed to evaluate the volumetric response of intracranial meningiomas at different time points after photon, proton, and a mixed photon and carbon ion boost irradiation. In Group A 38 patients received proton therapy (median dose: 56 GyE in 1.8-2 GyE daily fractions) or a mixed photon/carbon ion therapy (50 Gy in 2 Gy daily fractions with intensity modulated radiotherapy (IMRT) and 18 GyE in 3 GyE daily dose carbon ion boost). Thirty-nine patients (Group B) were treated by photon therapy with IMRT or fractionated stereotactic radiotherapy technique (median dose: 56 Gy in 1.8-2 Gy daily fractions). The delineation of the tumor volume was based on the initial, one- and two-year follow-up magnetic resonance imaging and these volumes were compared to evaluate the volumetric tumor response. Significant tumor volume shrinkage was detected at one- and at two-year follow-up both after irradiation by particles and by photons. No significant difference in tumor volume change was observed between photon, proton or combined photon plus carbon ion boost treated patients. WHO grade and gender appear to be determining factors for tumor volume shrinkage. Significant volumetric shrinkage of meningiomas could be observed independently of the applied radiation modality. Long-term follow-up is recommended to evaluate further dynamic of size reduction and its correlation with outcome data.

  14. Personalized heterogeneous deformable model for fast volumetric registration.

    PubMed

    Si, Weixin; Liao, Xiangyun; Wang, Qiong; Heng, Pheng Ann

    2017-02-20

    Biomechanical deformable volumetric registration can help improve safety of surgical interventions by ensuring the operations are extremely precise. However, this technique has been limited by the accuracy and the computational efficiency of patient-specific modeling. This study presents a tissue-tissue coupling strategy based on penalty method to model the heterogeneous behavior of deformable body, and estimate the personalized tissue-tissue coupling parameters in a data-driven way. Moreover, considering that the computational efficiency of biomechanical model is highly dependent on the mechanical resolution, a practical coarse-to-fine scheme is proposed to increase runtime efficiency. Particularly, a detail enrichment database is established in an offline fashion to represent the mapping relationship between the deformation results of high-resolution hexahedral mesh extracted from the raw medical data and a newly constructed low-resolution hexahedral mesh. At runtime, the mechanical behavior of human organ under interactions is simulated with this low-resolution hexahedral mesh, then the microstructures are synthesized in virtue of the detail enrichment database. The proposed method is validated by volumetric registration in an abdominal phantom compression experiments. Our personalized heterogeneous deformable model can well describe the coupling effects between different tissues of the phantom. Compared with high-resolution heterogeneous deformable model, the low-resolution deformable model with our detail enrichment database can achieve 9.4× faster, and the average target registration error is 3.42 mm, which demonstrates that the proposed method shows better volumetric registration performance than state-of-the-art. Our framework can well balance the precision and efficiency, and has great potential to be adopted in the practical augmented reality image-guided robotic systems.

  15. Volumetric breast density affects performance of digital screening mammography.

    PubMed

    Wanders, Johanna O P; Holland, Katharina; Veldhuis, Wouter B; Mann, Ritse M; Pijnappel, Ruud M; Peeters, Petra H M; van Gils, Carla H; Karssemeijer, Nico

    2017-02-01

    To determine to what extent automatically measured volumetric mammographic density influences screening performance when using digital mammography (DM). We collected a consecutive series of 111,898 DM examinations (2003-2011) from one screening unit of the Dutch biennial screening program (age 50-75 years). Volumetric mammographic density was automatically assessed using Volpara. We determined screening performance measures for four density categories comparable to the American College of Radiology (ACR) breast density categories. Of all the examinations, 21.6% were categorized as density category 1 ('almost entirely fatty') and 41.5, 28.9, and 8.0% as category 2-4 ('extremely dense'), respectively. We identified 667 screen-detected and 234 interval cancers. Interval cancer rates were 0.7, 1.9, 2.9, and 4.4‰ and false positive rates were 11.2, 15.1, 18.2, and 23.8‰ for categories 1-4, respectively (both p-trend < 0.001). The screening sensitivity, calculated as the proportion of screen-detected among the total of screen-detected and interval tumors, was lower in higher density categories: 85.7, 77.6, 69.5, and 61.0% for categories 1-4, respectively (p-trend < 0.001). Volumetric mammographic density, automatically measured on digital mammograms, impacts screening performance measures along the same patterns as established with ACR breast density categories. Since measuring breast density fully automatically has much higher reproducibility than visual assessment, this automatic method could help with implementing density-based supplemental screening.

  16. Extended Kalman filtering for continuous volumetric MR-temperature imaging.

    PubMed

    Denis de Senneville, Baudouin; Roujol, Sébastien; Hey, Silke; Moonen, Chrit; Ries, Mario

    2013-04-01

    Real time magnetic resonance (MR) thermometry has evolved into the method of choice for the guidance of high-intensity focused ultrasound (HIFU) interventions. For this role, MR-thermometry should preferably have a high temporal and spatial resolution and allow observing the temperature over the entire targeted area and its vicinity with a high accuracy. In addition, the precision of real time MR-thermometry for therapy guidance is generally limited by the available signal-to-noise ratio (SNR) and the influence of physiological noise. MR-guided HIFU would benefit of the large coverage volumetric temperature maps, including characterization of volumetric heating trajectories as well as near- and far-field heating. In this paper, continuous volumetric MR-temperature monitoring was obtained as follows. The targeted area was continuously scanned during the heating process by a multi-slice sequence. Measured data and a priori knowledge of 3-D data derived from a forecast based on a physical model were combined using an extended Kalman filter (EKF). The proposed reconstruction improved the temperature measurement resolution and precision while maintaining guaranteed output accuracy. The method was evaluated experimentally ex vivo on a phantom, and in vivo on a porcine kidney, using HIFU heating. On the in vivo experiment, it allowed the reconstruction from a spatio-temporally under-sampled data set (with an update rate for each voxel of 1.143 s) to a 3-D dataset covering a field of view of 142.5×285×54 mm(3) with a voxel size of 3×3×6 mm(3) and a temporal resolution of 0.127 s. The method also provided noise reduction, while having a minimal impact on accuracy and latency.

  17. Volumetric (tomographic) three-dimensional geoacoustic inversion in shallow water.

    PubMed

    Tolstoy, A

    2008-11-01

    Geoacoustic inversion is an important but difficult component for shallow water ocean acoustics. There are numerous methods in use to remotely determine bottom and geometric properties in both range-independent and range-dependent situations. While there have been some efforts to combine two-dimensional bottom estimates (range- and depth-dependent inversion slices) calculated around a receiving array into a three-dimensional (range, depth, and azimuthal) image of a region, there is only one approach in existence today, which attempts to determine consistent volumetric bottom properties using multiple arrays and multiple sources. This approach (geoacoustic tomography) will be discussed here (with final improvements via regularization).

  18. Volumetric relief map for intracranial cerebrospinal fluid distribution analysis.

    PubMed

    Lebret, Alain; Kenmochi, Yukiko; Hodel, Jérôme; Rahmouni, Alain; Decq, Philippe; Petit, Éric

    2015-09-01

    Cerebrospinal fluid imaging plays a significant role in the clinical diagnosis of brain disorders, such as hydrocephalus and Alzheimer's disease. While three-dimensional images of cerebrospinal fluid are very detailed, the complex structures they contain can be time-consuming and laborious to interpret. This paper presents a simple technique that represents the intracranial cerebrospinal fluid distribution as a two-dimensional image in such a way that the total fluid volume is preserved. We call this a volumetric relief map, and show its effectiveness in a characterization and analysis of fluid distributions and networks in hydrocephalus patients and healthy adults.

  19. Volumetric 3D Display System with Static Screen

    NASA Technical Reports Server (NTRS)

    Geng, Jason

    2011-01-01

    Current display technology has relied on flat, 2D screens that cannot truly convey the third dimension of visual information: depth. In contrast to conventional visualization that is primarily based on 2D flat screens, the volumetric 3D display possesses a true 3D display volume, and places physically each 3D voxel in displayed 3D images at the true 3D (x,y,z) spatial position. Each voxel, analogous to a pixel in a 2D image, emits light from that position to form a real 3D image in the eyes of the viewers. Such true volumetric 3D display technology provides both physiological (accommodation, convergence, binocular disparity, and motion parallax) and psychological (image size, linear perspective, shading, brightness, etc.) depth cues to human visual systems to help in the perception of 3D objects. In a volumetric 3D display, viewers can watch the displayed 3D images from a completely 360 view without using any special eyewear. The volumetric 3D display techniques may lead to a quantum leap in information display technology and can dramatically change the ways humans interact with computers, which can lead to significant improvements in the efficiency of learning and knowledge management processes. Within a block of glass, a large amount of tiny dots of voxels are created by using a recently available machining technique called laser subsurface engraving (LSE). The LSE is able to produce tiny physical crack points (as small as 0.05 mm in diameter) at any (x,y,z) location within the cube of transparent material. The crack dots, when illuminated by a light source, scatter the light around and form visible voxels within the 3D volume. The locations of these tiny voxels are strategically determined such that each can be illuminated by a light ray from a high-resolution digital mirror device (DMD) light engine. The distribution of these voxels occupies the full display volume within the static 3D glass screen. This design eliminates any moving screen seen in previous

  20. Marginal Space Deep Learning: Efficient Architecture for Volumetric Image Parsing.

    PubMed

    Ghesu, Florin C; Krubasik, Edward; Georgescu, Bogdan; Singh, Vivek; Zheng, Yefeng; Hornegger, Joachim; Comaniciu, Dorin

    2016-03-07

    Robust and fast solutions for anatomical object detection and segmentation support the entire clinical workflow from diagnosis, patient stratification, therapy planning, intervention and follow-up. Current state-of-the-art techniques for parsing volumetric medical image data are typically based on machine learning methods that exploit large annotated image databases. There are two main challenges that need to be addressed, these are the efficiency in processing large volumetric input images and the need for strong, representative image features. When the object of interest is parametrized in a high dimensional space, standard volume scanning techniques do not scale up to the enormous number of potential hypotheses and representative image features are subject to significant efforts of manual engineering. We propose a pipeline for object detection and segmentation in the context of volumetric image parsing, solving a two-step learning problem: anatomical pose estimation and boundary delineation. For this task we introduce Marginal Space Deep Learning (MSDL), a novel framework exploiting both the strengths of efficient object parametrization in hierarchical marginal spaces and the automated feature design of Deep Learning (DL) network architectures. Deep learning systems automatically identify, disentangle and learn explanatory attributes directly from low-level image data, however their application in the volumetric setting is limited by the very high complexity of the parametrization. More specifically 9 parameters are necessary to describe a restricted affine transformation in 3D (3 for each location, orientation, and scale) resulting in a prohibitive number of scanning hypotheses, in the order of billions for typical sampling. The mechanism of marginal space learning provides excellent run-time performance by learning classifiers in clustered, high-probability regions in spaces of gradually increasing dimensionality, for example starting from location only (3D

  1. Prognostic importance of volumetric measurements in stage I lung adenocarcinoma.

    PubMed

    Yanagawa, Masahiro; Tanaka, Yuko; Leung, Ann N; Morii, Eiichi; Kusumoto, Masahiko; Watanabe, Shunichi; Watanabe, Hirokazu; Inoue, Masayoshi; Okumura, Meinoshin; Gyobu, Tomoko; Ueda, Ken; Honda, Osamu; Sumikawa, Hiromitsu; Johkoh, Takeshi; Tomiyama, Noriyuki

    2014-08-01

    To perform volumetric analysis of stage I lung adenocarcinomas by using an automated computer program and to determine value of volumetric computed tomographic (CT) measurements associated with prognostic factors and outcome. Consecutive patients (n = 145) with stage I lung adenocarcinoma who underwent surgery after preoperative chest CT were enrolled. By using volumetric automated computer-assisted analytic program, nodules were classified into three subgroups: pure ground glass, part solid, or solid. Total tumor volume, solid tumor volume, and percentage of solid volume of each cancer were calculated after eliminating vessel components. One radiologist measured the longest diameter of the solid tumor component and of total tumor with their ratio, which was defined as solid proportion. The value of these quantitative data by examining associations with pathologic prognostic factors and outcome measures (disease-free survival and overall survival) were analyzed with logistic regression and Cox proportional hazards regression models, respectively. Significant parameters identified at univariate analysis were included in the multiple analyses. All 22 recurrences occurred in patients with nodules classified as part solid or solid. Multiple logistic regression analysis revealed that percentage of solid volume of 63% or greater was an independent indicator associated with pleural invasion (P = .01). Multiple Cox proportional hazards regression analysis revealed that percentage of solid volume of 63% or greater was a significant indicator of lower disease-free survival (hazard ratio, 18.45 [95% confidence interval: 4.34, 78.49]; P < .001). Both solid tumor volume of 1.5 cm(3) or greater and percentage of solid volume of 63% or greater were significant indicators of decreased overall survival (hazard ratio, 5.92 and 9.60, respectively [95% confidence interval: 1.17, 30.33 and 1.17, 78.91, respectively]; P = .034 and .036, respectively). Two volumetric measurements (solid

  2. Mucosal wrinkling in animal antra induced by volumetric growth

    NASA Astrophysics Data System (ADS)

    Li, Bo; Cao, Yan-Ping; Feng, Xi-Qiao; Yu, Shou-Wen

    2011-04-01

    Surface wrinkling of animal mucosas is crucial for the biological functions of some tissues, and the change in their surface patterns is a phenotypic characteristic of certain diseases. Here we develop a biomechanical model to study the relationship between morphogenesis and volumetric growth, either physiological or pathological, of mucosas. Theoretical analysis and numerical simulations are performed to unravel the critical characteristics of mucosal wrinkling in a spherical antrum. It is shown that the thicknesses and elastic moduli of mucosal and submucosal layers dictate the surface buckling morphology. The results hold clinical relevance for such diseases as inflammation and gastritis.

  3. Novel method for tracking in homogeneous volumetric media

    NASA Astrophysics Data System (ADS)

    Miller, Timothy N.; Butz, John; Milster, Thomas D.; Bletscher, Warren L.; Walker, Edwin P.; Park, Sang-Ki; Felix, David

    2003-09-01

    Volumetric media have great potential for meeting future optical data storage demands, but homogeneous media lack internal features for tracking. A novel method of tracking inside homogeneous media is described that uses external reference tracks attached to the media. Several possible configurations for implementing the "slave-servo" concept are described and compared. An optical design for the most promising configuration is presented. This desing utilizes a diffractive optical element for dispersion compensation. Modeling describes the limits of device performance and alignment. Early prototype results are presented.

  4. Basic Characteristics and Predicted Lifetime of Stacked Volumetric Optical Disks

    NASA Astrophysics Data System (ADS)

    Inaba, Akira; Ido, Hiroshi; Kishi, Hiroyuki; Yamanaka, Hideaki; Osawa, Seigo; Tani, Manabu; Uchida, Takeshi; Watanabe, Yutaka; Arai, Shinichi; Yoshihiro, Masafumi; Iida, Tamotsu; Awano, Hiroyuki; Ota, Norio; Yoshida, Takashi; Abe, Yukinobu; Yoshida, Kazushi

    2008-07-01

    A stacked volumetric optical disks (SVOD) system has been developed to achieve an over 1 Tbytes cartridge capacity using a commercialized drive and conventional recording layers. To confirm the reliability of thin optical disks in SVOD, several feasibility tests were conducted. The recording power margin, tilt margin and read stability of the thin optical disks were measured, and the lifetime of the thin optical disks was estimated. The results were similar to those of conventional 1.2-mm-thick optical disks regardless of the disk thickness.

  5. Synthesis of Volumetric Ring Antenna Array for Terrestrial Coverage Pattern

    PubMed Central

    Reyna, Alberto; Panduro, Marco A.; Del Rio Bocio, Carlos

    2014-01-01

    This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes X-Y, the positions of the rings on the plane X-Z, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction. PMID:24701150

  6. Two-Photon Laser Scanning Stereomicroscopy for Fast Volumetric Imaging

    PubMed Central

    Yang, Yanlong; Yao, Baoli; Lei, Ming; Dan, Dan; Li, Runze; Horn, Mark Van; Chen, Xun; Li, Yang; Ye, Tong

    2016-01-01

    Bessel beams have been successfully used in two-photon laser scanning fluorescence microscopy to extend the depth of field (EDF), which makes it possible to observe fast events volumetrically. However, the depth information is lost due to integration of fluorescence signals along the propagation direction. We describe the design and implementation of two-photon lasers scanning stereomicroscopy, which allows viewing dynamic processes in three-dimensional (3D) space stereoscopically in real-time with shutter glasses at the speed of 1.4 volumes per second. The depth information can be appreciated by human visual system or be recovered with correspondence algorithms for some cases. PMID:27997624

  7. Volumetric hemispheric ratio as a useful tool in personality psychology.

    PubMed

    Montag, Christian; Schoene-Bake, Jan-Christoph; Wagner, Jan; Reuter, Martin; Markett, Sebastian; Weber, Bernd; Quesada, Carlos M

    2013-02-01

    The present study investigates the link between volumetric hemispheric ratios (VHRs) and personality measures in N=267 healthy participants using Eysenck's Personality Inventory-Revised (EPQ-R) and the BIS/BAS scales. A robust association between extraversion and VHRs was observed for gray matter in males but not females. Higher gray matter volume in the left than in the right hemisphere was associated with higher extraversion in males. The results are discussed in the context of positive emotionality and laterality of the human brain.

  8. No volumetric differences in the anterior cingulate of psychopathic individuals

    PubMed Central

    Glenn, Andrea L.; Yang, Yaling; Raine, Adrian; Colletti, Patrick

    2010-01-01

    Functional imaging studies of psychopathy have demonstrated reduced activity in the anterior cingulate, yet it is unclear whether this region is structurally impaired. In this study, we used structural MRI to examine whether volumetric differences exist in the anterior cingulate between psychopathic (n=24) and control (n=24) male participants. We found no group differences in the volume of the anterior cingulate or its dorsal and ventral subregions. Our findings call into question whether the anterior cingulate is impaired in psychopathy, or whether previous findings of reduced activity may result from reduced input from other deficient regions. PMID:20630717

  9. Application of the sonic volumetric scan log to cement evaluation

    SciTech Connect

    Broding, R.A.

    1984-01-01

    The imaging process of a volumetric scan presentation produces a sonic image that gives a pictorial display of the cement in place. The cemented zone can be further evaluated from transmittance and velocity scans. The image can be selected to include the casing to cement bond, the full cemented zone or the cement to formation bond. Sectoring, tilting and rotation of the image allows one to quickly make a first interpretation for any suspect areas. A more detailed study from transmittance and velocity data permits a reliable qualification of the physical properties of the cement in place.

  10. Drop size selection in axially heated co-axial fiber capillary instability

    NASA Astrophysics Data System (ADS)

    Mowlavi, Saviz; Brun, Pierre-Thomas; Gallaire, Francois

    2015-11-01

    We analyze the sphere size selection mechanism in silicon-in-silica sphere formation through the application of an external axial thermal gradient to a co-axial silicon-in-silica fiber (Gumennik et al., Nature Com., 2013). We first apply a convective/absolute stability analysis to the in-fibre capillary instability governing the sphere formation and demonstrate that the resulting wavelength selection predicts a finite but still too large wavelength. A global stability analysis is then pursued, which accounts for the spatial inhomogeneity of the base flow. F.G. acknowledges funding from ERC SimCoMiCs 280117.

  11. Designing and updating the flow part of axial and radial-axial turbines through mathematical modeling

    NASA Astrophysics Data System (ADS)

    Rusanov, Andrey; Rusanov, Roman; Lampart, Piotr

    2015-10-01

    The paper describes an algorithm for the design of axial and radial-axial type turbines. The algorithm is based on using mathematical models of various levels of complexity - from 1D to 3D. Flow path geometry is described by means of analytical methods of profiling using a limited number of parameters. 3D turbulent flow model is realised in the program complex IPMFlow, developed based on the earlier codes FlowER and FlowER-U. Examples of developed or modernized turbines for differentpurpose power machines are presented. They are: an expansion turbine, ORC turbine and cogeneration mediumpressure turbine.

  12. Design, operation and applications of a visible-light confocal scanning Fourier transform Raman microscope for volumetric Raman spectrochemical imaging

    NASA Astrophysics Data System (ADS)

    Brenan, Colin John Herbert

    A new type of confocal Raman microscope called a Fourier transform confocal Raman microscope (FT-CRM) was designed, built and characterized with respect to its spatio-spectral imaging properties. Several different applications of the FT-CRM are presented that take advantage of its unique spectral and spatial imaging characteristics. The instrument combines focused illumination with spatially-filtered detection in a confocal optical configuration to collect photons scattered from a diffraction-limited volume in the sample (typically [<]5×10-18/ m3) and reject photons from outside that region. The molecular vibrational information encoded in the inelastic, or Raman, spectral component of light scattered from the confocal volume is measured with a visible light Fourier transform Raman spectrometer. By scanning the sample relative to the confocal volume, a volumetric Raman spectrochemical image of the sample can be constructed. Raman scattering is an inherently inefficient process; hence an optimal radius pinhole must be found that balances the FT-CRM optical throughput against the microscope spatial resolution and image contrast. Detailed experimental measurements mapped out the FT-CRM spatial response (axial and lateral), optical throughput and image signal-to-background and signal-to-noise ratios as a function of pinhole radius. Excellent agreement was found between these measurements and the predictions of a theoretical microscope model also developed as part of this thesis. Several applications of the FT-CRM included volumetric compositional imaging of three-dimensional chemically inhomogeneous materials such as cellulose and polyester fibers in water or two immiscible optically- similar liquids, water and trichloroehthylene, in a porous quartz sandstone matrix. The potential of the FT- CRM for non-invasive spectrochemical detection and imaging through a turbid tissue-like medium was demonstrated and a new spectral estimator, Fast Orthogonal Search, was evaluated

  13. Floating volumetric image formation using a dihedral corner reflector array device.

    PubMed

    Miyazaki, Daisuke; Hirano, Noboru; Maeda, Yuki; Yamamoto, Siori; Mukai, Takaaki; Maekawa, Satoshi

    2013-01-01

    A volumetric display system using an optical imaging device consisting of numerous dihedral corner reflectors placed perpendicular to the surface of a metal plate is proposed. Image formation by the dihedral corner reflector array (DCRA) is free from distortion and focal length. In the proposed volumetric display system, a two-dimensional real image is moved by a mirror scanner to scan a three-dimensional (3D) space. Cross-sectional images of a 3D object are displayed in accordance with the position of the image plane. A volumetric image is observed as a stack of the cross-sectional images. The use of the DCRA brings compact system configuration and volumetric real image generation with very low distortion. An experimental volumetric display system including a DCRA, a galvanometer mirror, and a digital micro-mirror device was constructed to verify the proposed method. A volumetric image consisting of 1024×768×400 voxels was formed by the experimental system.

  14. Electronic and optical properties of silicene under uni-axial and bi-axial mechanical strains: A first principle study

    NASA Astrophysics Data System (ADS)

    Mohan, Brij; Kumar, Ashok; Ahluwalia, P. K.

    2014-07-01

    The uni-axial and bi-axial mechanical strain mediated electronic band structures and dielectric properties of silicene have been investigated. It is found that on applying uni- and bi-axial strains, the band gap opens for smaller strain in silicene. However, on further increase of strain beyond 8% silicene changed into metal. The ultimate tensile strength estimated is 3.4 GPa. Imaginary part of dielectric function shows that the inter-band transitions are red-shifted for uni- and bi-axial tensile strains and are blue shifted for uni- and bi-axial compressive strains. Electron energy loss (EEL) function shows that the π+σ plasmon energies are red-shifted for uni- and bi-axial strains and blue-shifted for compressive strains. The π plasmons disappears for tensile and asymmetric strains. Bi-axial asymmetric strain is found to have no influence on inter-band transitions and π+σ plasmon energies.

  15. Digital enhancement of computerized axial tomograms

    NASA Technical Reports Server (NTRS)

    Roberts, E., Jr.

    1978-01-01

    A systematic evaluation has been conducted of certain digital image enhancement techniques performed in image space. Three types of images have been used, computer generated phantoms, tomograms of a synthetic phantom, and axial tomograms of human anatomy containing images of lesions, artificially introduced into the tomograms. Several types of smoothing, sharpening, and histogram modification have been explored. It has been concluded that the most useful enhancement techniques are a selective smoothing of singular picture elements, combined with contrast manipulation. The most useful tool in applying these techniques is the gray-scale histogram.

  16. Digital enhancement of computerized axial tomograms

    NASA Technical Reports Server (NTRS)

    Roberts, E., Jr.

    1978-01-01

    A systematic evaluation was conducted of certain digital image enhancement techniques performed in image space. Three types of images were used, computer generated phantoms, tomograms of a synthetic phantom, and axial tomograms of human anatomy containing images of lesions, artificially introduced into the tomograms. Several types of smoothing, sharpening, and histogram modification were explored. It was concluded that the most useful enhancement techniques are a selective smoothing of singular picture elements, combined with contrast manipulation. The most useful tool in applying these techniques is the gray-scale histogram.

  17. Axial Tomography from Digitized Real Time Radiography

    DOE R&D Accomplishments Database

    Zolnay, A. S.; McDonald, W. M.; Doupont, P. A.; McKinney, R. L.; Lee, M. M.

    1985-01-18

    Axial tomography from digitized real time radiographs provides a useful tool for industrial radiography and tomography. The components of this system are: x-ray source, image intensifier, video camera, video line extractor and digitizer, data storage and reconstruction computers. With this system it is possible to view a two dimensional x-ray image in real time at each angle of rotation and select the tomography plane of interest by choosing which video line to digitize. The digitization of a video line requires less than a second making data acquisition relatively short. Further improvements on this system are planned and initial results are reported.

  18. Water ingestion into jet engine axial compressors

    NASA Technical Reports Server (NTRS)

    Tsuchiya, T.; Murthy, S. N. B.

    1982-01-01

    An axial flow compressor has been tested with water droplet ingestion under a variety of conditions. The results illustrate the manner in which the compressor pressure ratio, efficiency and surging characteristics are affected. A model for estimating the performance of a compressor during water ingestion has been developed and the predictions obtained compare favorably with the test results. It is then shown that with respect to five droplet-associated nonlinearly-interacting processes (namely, droplet-blade interactions, blade performance changes, centrifugal action, heat and mass transfer processes and droplet break-up), the initial water content and centrifugal action play the most dominant roles.

  19. Flow field visualization about external axial corners

    NASA Technical Reports Server (NTRS)

    Talcott, N. A., Jr.

    1978-01-01

    An experimental investigation was conducted to visualize the flow field about external axial corners. The investigation was initiated to provide answers to questions about the inviscid flow pattern for continuing numerical investigations. Symmetrical and asymmetrical corner models were tested at a Reynolds number per meter of 60,700,000. Oil-flow and vapor-screen photographs were taken for both models at angle of attack and yaw. The paper presents the results of the investigation in the form of oil-flow photographs and the surrounding shock wave location obtained from the vapor screens.

  20. Scalar resonances in axially symmetric spacetimes

    NASA Astrophysics Data System (ADS)

    Ranea-Sandoval, Ignacio F.; Vucetich, Héctor

    2015-03-01

    We study properties of resonant solutions to the scalar wave equation in several axially symmetric spacetimes. We prove that nonaxial resonant modes do not exist neither in the Lanczos dust cylinder, the extreme (2 + 1) dimensional Bañados-Taitelboim-Zanelli (BTZ) spacetime nor in a class of simple rotating wormhole solutions. Moreover, we find unstable solutions to the wave equation in the Lanczos dust cylinder and in the r2 < 0 region of the extreme (2 + 1) dimensional BTZ spacetime, two solutions that possess closed timelike curves. Similarities with previous results obtained for the Kerr spacetime are explored.

  1. Water ingestion into jet engine axial compressors

    NASA Technical Reports Server (NTRS)

    Tsuchiya, T.; Murthy, S. N. B.

    1982-01-01

    An axial flow compressor has been tested with water droplet ingestion under a variety of conditions. The results illustrate the manner in which the compressor pressure ratio, efficiency and surging characteristics are affected. A model for estimating the performance of a compressor during water ingestion has been developed and the predictions obtained compare favorably with the test results. It is then shown that with respect to five droplet-associated nonlinearly-interacting processes (namely, droplet-blade interactions, blade performance changes, centrifugal action, heat and mass transfer processes and droplet break-up), the initial water content and centrifugal action play the most dominant roles.

  2. Axial tomography from digitized real time radiography

    SciTech Connect

    Zolnay, A.S.; McDonald, W.M.; Doupont, P.A.; McKinney, R.L.; Lee, M.M.

    1985-01-18

    Axial tomography from digitized real time radiographs provides a useful tool for industrial radiography and tomography. The components of this system are: x-ray source, image intensifier, video camera, video line extractor and digitizer, data storage and reconstruction computers. With this system it is possible to view a two dimensional x-ray image in real time at each angle of rotation and select the tomography plane of interest by choosing which video line to digitize. The digitization of a video line requires less than a second making data acquisition relatively short. Further improvements on this system are planned and initial results are reported.

  3. CBCT-based volumetric and dosimetric variation evaluation of volumetric modulated arc radiotherapy in the treatment of nasopharyngeal cancer patients

    PubMed Central

    2013-01-01

    Objective To investigate the anatomic and dosimetric variations of volumetric modulated arc therapy (VMAT) in the treatment of nasopharyngeal cancer (NPC) patients based on weekly cone beam CT (CBCT). Materials and methods Ten NPC patients treated by VMAT with weekly CBCT for setup corrections were reviewed retrospectively. Deformed volumes of targets and organs at risk (OARs) in the CBCT were compared with those in the planning CT. Delivered doses were recalculated based on weekly CBCT and compared with the planned doses. Results No significant volumetric changes on targets, brainstem, and spinal cord were observed. The average volumes of right and left parotid measured from the fifth CBCT were about 4.4 and 4.5 cm3 less than those from the first CBCT, respectively. There were no significant dose differences between average planned and delivered doses for targets, brainstem and spinal cord. For right parotid, the delivered mean dose was 10.5 cGy higher (p = 0.004) than the planned value per fraction, and the V26 and V32 increased by 7.5% (p = 0.002) and 7.4% (p = 0.01), respectively. For the left parotid, the D50 (dose to the 50% volume) was 8.8 cGy higher (p = 0.03) than the planned values per fraction, and the V26 increased by 8.8% (p = 0.002). Conclusion Weekly CBCTs were applied directly to study the continuous volume changes and resulting dosimetric variations of targets and OARs for NPC patients undergoing VMAT. Significant volumetric and dosimetric variations were observed for parotids. Replanning after 30 Gy will benefit the protection on parotids. PMID:24289312

  4. Volumetric three-dimensional display system with rasterization hardware

    NASA Astrophysics Data System (ADS)

    Favalora, Gregg E.; Dorval, Rick K.; Hall, Deirdre M.; Giovinco, Michael; Napoli, Joshua

    2001-06-01

    An 8-color multiplanar volumetric display is being developed by Actuality Systems, Inc. It will be capable of utilizing an image volume greater than 90 million voxels, which we believe is the greatest utilizable voxel set of any volumetric display constructed to date. The display is designed to be used for molecular visualization, mechanical CAD, e-commerce, entertainment, and medical imaging. As such, it contains a new graphics processing architecture, novel high-performance line- drawing algorithms, and an API similar to a current standard. Three-dimensional imagery is created by projecting a series of 2-D bitmaps ('image slices') onto a diffuse screen that rotates at 600 rpm. Persistence of vision fuses the slices into a volume-filling 3-D image. A modified three-panel Texas Instruments projector provides slices at approximately 4 kHz, resulting in 8-color 3-D imagery comprised of roughly 200 radially-disposed slices which are updated at 20 Hz. Each slice has a resolution of 768 by 768 pixels, subtending 10 inches. An unusual off-axis projection scheme incorporating tilted rotating optics is used to maintain good focus across the projection screen. The display electronics includes a custom rasterization architecture which converts the user's 3- D geometry data into image slices, as well as 6 Gbits of DDR SDRAM graphics memory.

  5. Computational assessment of visual search strategies in volumetric medical images

    PubMed Central

    Wen, Gezheng; Aizenman, Avigael; Drew, Trafton; Wolfe, Jeremy M.; Haygood, Tamara Miner; Markey, Mia K.

    2016-01-01

    Abstract. When searching through volumetric images [e.g., computed tomography (CT)], radiologists appear to use two different search strategies: “drilling” (restrict eye movements to a small region of the image while quickly scrolling through slices), or “scanning” (search over large areas at a given depth before moving on to the next slice). To computationally identify the type of image information that is used in these two strategies, 23 naïve observers were instructed with either “drilling” or “scanning” when searching for target T’s in 20 volumes of faux lung CTs. We computed saliency maps using both classical two-dimensional (2-D) saliency, and a three-dimensional (3-D) dynamic saliency that captures the characteristics of scrolling through slices. Comparing observers’ gaze distributions with the saliency maps showed that search strategy alters the type of saliency that attracts fixations. Drillers’ fixations aligned better with dynamic saliency and scanners with 2-D saliency. The computed saliency was greater for detected targets than for missed targets. Similar results were observed in data from 19 radiologists who searched five stacks of clinical chest CTs for lung nodules. Dynamic saliency may be superior to the 2-D saliency for detecting targets embedded in volumetric images, and thus “drilling” may be more efficient than “scanning.” PMID:26759815

  6. Scanners and drillers: Characterizing expert visual search through volumetric images

    PubMed Central

    Drew, Trafton; Vo, Melissa Le-Hoa; Olwal, Alex; Jacobson, Francine; Seltzer, Steven E.; Wolfe, Jeremy M.

    2013-01-01

    Modern imaging methods like computed tomography (CT) generate 3-D volumes of image data. How do radiologists search through such images? Are certain strategies more efficient? Although there is a large literature devoted to understanding search in 2-D, relatively little is known about search in volumetric space. In recent years, with the ever-increasing popularity of volumetric medical imaging, this question has taken on increased importance as we try to understand, and ultimately reduce, errors in diagnostic radiology. In the current study, we asked 24 radiologists to search chest CTs for lung nodules that could indicate lung cancer. To search, radiologists scrolled up and down through a “stack” of 2-D chest CT “slices.” At each moment, we tracked eye movements in the 2-D image plane and coregistered eye position with the current slice. We used these data to create a 3-D representation of the eye movements through the image volume. Radiologists tended to follow one of two dominant search strategies: “drilling” and “scanning.” Drillers restrict eye movements to a small region of the lung while quickly scrolling through depth. Scanners move more slowly through depth and search an entire level of the lung before moving on to the next level in depth. Driller performance was superior to the scanners on a variety of metrics, including lung nodule detection rate, percentage of the lung covered, and the percentage of search errors where a nodule was never fixated. PMID:23922445

  7. Photoacoustic analysis of proteins: volumetric signals and fluorescence quantum yields.

    PubMed Central

    Kurian, E; Prendergast, F G; Small, J R

    1997-01-01

    A series of proteins has been examined using time-resolved, pulsed-laser volumetric photoacoustic spectroscopy. Photoacoustic waveforms were collected to measure heat release for calculation of fluorescence quantum yields, and to explore the possibility of photoinduced nonthermal volume changes occurring in these protein samples. The proteins studied were the green fluorescent protein (GFP); intestinal fatty acid binding protein (IFABP), and adipocyte lipid-binding protein (ALBP), each labeled noncovalently with 1-anilinonaphthalene-8-sulfonate (1,8-ANS) and covalently with 6-acryloyl-2-(dimethylamino)naphthalene (acrylodan); and acrylodan-labeled IFABP and ALBP with added oleic acid. Of this group of proteins, only the ALBP labeled with 1,8-ANS showed significant nonthermal volume changes at the beta = 0 temperature (approximately 3.8 degrees C) for the buffer used (10 mM Tris-HCI, pH 7.5) (beta is the thermal cubic volumetric expansion coefficient). For all of the proteins except for acrylodan-labeled IFABP, the fluorescence quantum yields calculated assuming simple energy conservation were anomalously high, i.e., the apparent heat signals were lower than those predicted from independent fluorescence measurements. The consistent anomalies suggest that the low photoacoustic signals may be characteristic of fluorophores buried in proteins, and that photoacoustic signals derive in part from the microenvironment of the absorbing chromophore. Images FIGURE 1 PMID:9199809

  8. Volumetric intraoperative brain deformation compensation: model development and phantom validation.

    PubMed

    DeLorenzo, Christine; Papademetris, Xenophon; Staib, Lawrence H; Vives, Kenneth P; Spencer, Dennis D; Duncan, James S

    2012-08-01

    During neurosurgery, nonrigid brain deformation may affect the reliability of tissue localization based on preoperative images. To provide accurate surgical guidance in these cases, preoperative images must be updated to reflect the intraoperative brain. This can be accomplished by warping these preoperative images using a biomechanical model. Due to the possible complexity of this deformation, intraoperative information is often required to guide the model solution. In this paper, a linear elastic model of the brain is developed to infer volumetric brain deformation associated with measured intraoperative cortical surface displacement. The developed model relies on known material properties of brain tissue, and does not require further knowledge about intraoperative conditions. To provide an initial estimation of volumetric model accuracy, as well as determine the model's sensitivity to the specified material parameters and surface displacements, a realistic brain phantom was developed. Phantom results indicate that the linear elastic model significantly reduced localization error due to brain shift, from > 16 mm to under 5 mm, on average. In addition, though in vivo quantitative validation is necessary, preliminary application of this approach to images acquired during neocortical epilepsy cases confirms the feasibility of applying the developed model to in vivo data.

  9. Investigation of Volumetric Sources in Airframe Noise Simulations

    NASA Technical Reports Server (NTRS)

    Casper, Jay H.; Lockard, David P.; Khorrami, Mehdi R.; Streett, Craig L.

    2004-01-01

    Hybrid methods for the prediction of airframe noise involve a simulation of the near field flow that is used as input to an acoustic propagation formula. The acoustic formulations discussed herein are those based on the Ffowcs Williams and Hawkings equation. Some questions have arisen in the published literature in regard to an apparently significant dependence of radiated noise predictions on the location of the integration surface used in the solution of the Ffowcs Williams and Hawkings equation. These differences in radiated noise levels are most pronounced between solid-body surface integrals and off-body, permeable surface integrals. Such differences suggest that either a non-negligible volumetric source is contributing to the total radiation or the input flow simulation is suspect. The focus of the current work is the issue of internal consistency of the flow calculations that are currently used as input to airframe noise predictions. The case study for this research is a computer simulation for a three-element, high-lift wing profile during landing conditions. The noise radiated from this flow is predicted by a two-dimensional, frequency-domain formulation of the Ffowcs Williams and Hawkings equation. Radiated sound from volumetric sources is assessed by comparison of a permeable surface integration with the sum of a solid-body surface integral and a volume integral. The separate noise predictions are found in good agreement.

  10. Multi-sensor 3D volumetric reconstruction using CUDA

    NASA Astrophysics Data System (ADS)

    Aliakbarpour, Hadi; Almeida, Luis; Menezes, Paulo; Dias, Jorge

    2011-12-01

    This paper presents a full-body volumetric reconstruction of a person in a scene using a sensor network, where some of them can be mobile. The sensor network is comprised of couples of camera and inertial sensor (IS). Taking advantage of IS, the 3D reconstruction is performed using no planar ground assumption. Moreover, IS in each couple is used to define a virtual camera whose image plane is horizontal and aligned with the earth cardinal directions. The IS is furthermore used to define a set of inertial planes in the scene. The image plane of each virtual camera is projected onto this set of parallel-horizontal inertial-planes, using some adapted homography functions. A parallel processing architecture is proposed in order to perform human real-time volumetric reconstruction. The real-time characteristic is obtained by implementing the reconstruction algorithm on a graphics processing unit (GPU) using Compute Unified Device Architecture (CUDA). In order to show the effectiveness of the proposed algorithm, a variety of the gestures of a person acting in the scene is reconstructed and demonstrated. Some analyses have been carried out to measure the performance of the algorithm in terms of processing time. The proposed framework has potential to be used by different applications such as smart-room, human behavior analysis and 3D teleconference. [Figure not available: see fulltext.

  11. Volumetric capnography and chronic obstructive pulmonary disease staging

    PubMed Central

    Romero, Pablo V; Rodriguez, Benigno; de Oliveira, Daniela; Blanch, L; Manresa, Federico

    2007-01-01

    Spirometry is difficult for some COPD patient to perform. Volumetric capnography could be a second choice test to evaluate the severity of functional disturbances. The aim of this work is to test this hypothesis. A total number of 98 subjects were classified either as normal ex-smokers (N = 14) or COPD patients. The latter were staged following GOLD recommendations. Spirometry and volumetric capnography recordings were obtained from each patient. Spirometry parameters, Bohr Dead Space (VD Bohr), Airways Dead Space from the pre-interface expirate corrected curve (VD aw), Phase III slope (SlIII) and Volume of alveolar ejection (VAE) were measured. Index of Ventilatory Efficiency (IVE), and Index of Airways Heterogeneity (IAH) were calculated as: IVE = VAE/(VT – VD aw) and IAH = 1 – [(VT – VD Bohr)/(VT – VD aw)]. In ANOCOVA analysis IAH showed the greatest association with stage (F > 40), with no significant covariant dependence on VT. A receiver operating characteristics curve analysis showed values of the area under the curve greater than 0.9 for IAH and IVE at all stage levels, with a sensitivity = specificity value greater than 80%. We conclude that IAH and IVE can be used when spirometry cannot be reliably performed, as an alternative test to evaluate the degree of functional involvement in COPD patients. PMID:18229577

  12. Scanners and drillers: characterizing expert visual search through volumetric images.

    PubMed

    Drew, Trafton; Vo, Melissa Le-Hoa; Olwal, Alex; Jacobson, Francine; Seltzer, Steven E; Wolfe, Jeremy M

    2013-08-06

    Modern imaging methods like computed tomography (CT) generate 3-D volumes of image data. How do radiologists search through such images? Are certain strategies more efficient? Although there is a large literature devoted to understanding search in 2-D, relatively little is known about search in volumetric space. In recent years, with the ever-increasing popularity of volumetric medical imaging, this question has taken on increased importance as we try to understand, and ultimately reduce, errors in diagnostic radiology. In the current study, we asked 24 radiologists to search chest CTs for lung nodules that could indicate lung cancer. To search, radiologists scrolled up and down through a "stack" of 2-D chest CT "slices." At each moment, we tracked eye movements in the 2-D image plane and coregistered eye position with the current slice. We used these data to create a 3-D representation of the eye movements through the image volume. Radiologists tended to follow one of two dominant search strategies: "drilling" and "scanning." Drillers restrict eye movements to a small region of the lung while quickly scrolling through depth. Scanners move more slowly through depth and search an entire level of the lung before moving on to the next level in depth. Driller performance was superior to the scanners on a variety of metrics, including lung nodule detection rate, percentage of the lung covered, and the percentage of search errors where a nodule was never fixated.

  13. [Benefits of volumetric to facial rejuvenation. Part 1: Fat grafting].

    PubMed

    Bui, P; Lepage, C

    2017-09-05

    For a number of years, a volumetric approach using autologous fat injection has been implemented to improve cosmetic outcome in face-lift procedures and to achieve lasting rejuvenation. Autologous fat as filling tissue has been used in plastic surgery since the late 19th century, but has only recently been associated to face lift procedures. The interest of the association lies on the one hand in the pathophysiology of facial aging, involving skin sag and loss of volume, and on the other hand in the tissue induction properties of grafted fat, "rejuvenating" the injected area. The strict methodology consisting in harvesting, treating then injecting an autologous fat graft is known as LipoStructure(®) or lipofilling. We here describe the technique overall, then region by region. It is now well known and seems simple, effective and reproducible, but is nevertheless delicate. For each individual, it is necessary to restore a harmonious face with well-distributed volumes. By associating volumetric to the face lift procedure, the plastic surgeon plays a new role: instead of being a tailor, cutting away excess skin, he or she becomes a sculptor, remodeling the face to restore the harmony of youth. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  14. Evolution of a turbulent jet subjected to volumetric heating

    NASA Astrophysics Data System (ADS)

    Agrawal, Amit; Prasad, Ajay K.

    2004-07-01

    The goal of this study is to understand the effect of latent heat release on entrainment in cumulus clouds by employing a laboratory analogue consisting of a volumetrically heated turbulent axisymmetric jet. The jet fluid is volumetrically heated in an off-source manner to simulate condensation heat release in clouds. The experimental set-up is similar to Bhat & Narasimha (1996), and the current application of wholefield velocimetry and thermometry has allowed us to probe in detail the velocity and temperature fields within the heat injection zone (HIZ) for the first time, leading to several new results. We are able to demarcate three distinct zones within the HIZ based primarily on the nature of the cross-stream velocity profile, and we present sharp differences in flow properties in these zones. Thermochromic liquid crystal-based temperature visualizations have revealed details about the complex interplay of velocity, local concentration and temperature leading to a physically coherent understanding of this flow. We also provide evidence using linear stochastic estimates (LSE) to show that large eddies are disrupted in the latter part of the HIZ; the disruption of large eddies is linked to the change in the nature of the cross-stream velocity profile. While our results have confirmed certain previously reported observations such as a reduction in scalar width, we have measured significantly larger r.m.s. values within the HIZ than previously reported, which is corroborated by direct numerical simulation results.

  15. Volumetric Flow Measurement Using an Implantable CMUT Array.

    PubMed

    Mengli Wang; Jingkuang Chen

    2011-06-01

    This paper describes volumetric-flow velocity measurement using an implantable capacitive micromachined ultrasonic transducer (CMUT) array. The array is comprised of multiple-concentric CMUT rings for ultrasound transmission and an outmost annular CMUT array for ultrasound reception. Microelectromechanical-system (MEMS) fabrication technology allows reception CMUT on this flowmeter to be implemented with a different membrane thickness and gap height than that of transmission CMUTs, optimizing the performance of these two different kinds of devices. The silicon substrate of this 2-mm-diameter CMUT ring array was bulk micromachined to approximately 80 to 100 μm thick, minimizing tissue disruption. The blood-flow velocity was detected using pulse ultrasound Doppler by comparing the demodulated echo ultrasound with the incident ultrasound. The demodulated ultrasound signal was sampled by a pulse delayed in time domain from the transmitted burst, which corresponds to detecting the signal at a specific distance. The flow tube/vessel diameter was detected through the time-flight delay difference from near and far wall reflections, which was measured from the ultrasound pulse echo. The angle between the ultrasound beam and the flow was found by using the cross-correlation from consecutive ultrasound echoes. Artificial blood flowing through three different polymer tubes was experimented with, while keeping the same volumetric flow rate. The discrepancy in flow measurement results between this CMUT meter and a calibrated laser Doppler flowmeter is less than 5%.

  16. High volumetric power density, non-enzymatic, glucose fuel cells

    PubMed Central

    Oncescu, Vlad; Erickson, David

    2013-01-01

    The development of new implantable medical devices has been limited in the past by slow advances in lithium battery technology. Non-enzymatic glucose fuel cells are promising replacement candidates for lithium batteries because of good long-term stability and adequate power density. The devices developed to date however use an “oxygen depletion design” whereby the electrodes are stacked on top of each other leading to low volumetric power density and complicated fabrication protocols. Here we have developed a novel single-layer fuel cell with good performance (2 μW cm−2) and stability that can be integrated directly as a coating layer on large implantable devices, or stacked to obtain a high volumetric power density (over 16 μW cm−3). This represents the first demonstration of a low volume non-enzymatic fuel cell stack with high power density, greatly increasing the range of applications for non-enzymatic glucose fuel cells. PMID:23390576

  17. Volumetric Intraoperative Brain Deformation Compensation: Model Development and Phantom Validation

    PubMed Central

    DeLorenzo, Christine; Papademetris, Xenophon; Staib, Lawrence H.; Vives, Kenneth P.; Spencer, Dennis D.; Duncan, James S.

    2012-01-01

    During neurosurgery, nonrigid brain deformation may affect the reliability of tissue localization based on preoperative images. To provide accurate surgical guidance in these cases, preoperative images must be updated to reflect the intraoperative brain. This can be accomplished by warping these preoperative images using a biomechanical model. Due to the possible complexity of this deformation, intraoperative information is often required to guide the model solution. In this paper, a linear elastic model of the brain is developed to infer volumetric brain deformation associated with measured intraoperative cortical surface displacement. The developed model relies on known material properties of brain tissue, and does not require further knowledge about intraoperative conditions. To provide an initial estimation of volumetric model accuracy, as well as determine the model’s sensitivity to the specified material parameters and surface displacements, a realistic brain phantom was developed. Phantom results indicate that the linear elastic model significantly reduced localization error due to brain shift, from >16 mm to under 5 mm, on average. In addition, though in vivo quantitative validation is necessary, preliminary application of this approach to images acquired during neocortical epilepsy cases confirms the feasibility of applying the developed model to in vivo data. PMID:22562728

  18. Volumetric properties of human islet amyloid polypeptide in liquid water.

    PubMed

    Brovchenko, I; Andrews, M N; Oleinikova, A

    2010-04-28

    The volumetric properties of human islet amyloid polypeptide (hIAPP) in water were studied in a wide temperature range by computer simulations. The intrinsic density rho(p) and the intrinsic thermal expansion coefficient alpha(p) of hIAPP were evaluated by taking into account the difference between the volumetric properties of hydration and bulk water. The density of hydration water rho(h) was found to decrease almost linearly with temperature upon heating and its thermal expansion coefficient was found to be notably higher than that of bulk water. The peptide surface exposed to water is more hydrophobic and its rho(h) is smaller in conformation with a larger number of intrapeptide hydrogen bonds. The two hIAPP peptides studied (with and without disulfide bridge) show negative alpha(p), which is close to zero at 250 K and decreases to approximately -1.5 x 10(-3) K(-1) upon heating to 450 K. The analysis of various structural properties of peptides shows a correlation between the intrinsic peptide volumes and the number of intrapeptide hydrogen bonds. The obtained negative values of alpha(p) can be attributed to the shrinkage of the inner voids of the peptides upon heating.

  19. Volumetric display containing multiple two-dimensional color motion pictures

    NASA Astrophysics Data System (ADS)

    Hirayama, R.; Shiraki, A.; Nakayama, H.; Kakue, T.; Shimobaba, T.; Ito, T.

    2014-06-01

    We have developed an algorithm which can record multiple two-dimensional (2-D) gradated projection patterns in a single three-dimensional (3-D) object. Each recorded pattern has the individual projected direction and can only be seen from the direction. The proposed algorithm has two important features: the number of recorded patterns is theoretically infinite and no meaningful pattern can be seen outside of the projected directions. In this paper, we expanded the algorithm to record multiple 2-D projection patterns in color. There are two popular ways of color mixing: additive one and subtractive one. Additive color mixing used to mix light is based on RGB colors and subtractive color mixing used to mix inks is based on CMY colors. We made two coloring methods based on the additive mixing and subtractive mixing. We performed numerical simulations of the coloring methods, and confirmed their effectiveness. We also fabricated two types of volumetric display and applied the proposed algorithm to them. One is a cubic displays constructed by light-emitting diodes (LEDs) in 8×8×8 array. Lighting patterns of LEDs are controlled by a microcomputer board. The other one is made of 7×7 array of threads. Each thread is illuminated by a projector connected with PC. As a result of the implementation, we succeeded in recording multiple 2-D color motion pictures in the volumetric displays. Our algorithm can be applied to digital signage, media art and so forth.

  20. Volumetric verification of multiaxis machine tool using laser tracker.

    PubMed

    Aguado, Sergio; Samper, David; Santolaria, Jorge; Aguilar, Juan José

    2014-01-01

    This paper aims to present a method of volumetric verification in machine tools with linear and rotary axes using a laser tracker. Beyond a method for a particular machine, it presents a methodology that can be used in any machine type. Along this paper, the schema and kinematic model of a machine with three axes of movement, two linear and one rotational axes, including the measurement system and the nominal rotation matrix of the rotational axis are presented. Using this, the machine tool volumetric error is obtained and nonlinear optimization techniques are employed to improve the accuracy of the machine tool. The verification provides a mathematical, not physical, compensation, in less time than other methods of verification by means of the indirect measurement of geometric errors of the machine from the linear and rotary axes. This paper presents an extensive study about the appropriateness and drawbacks of the regression function employed depending on the types of movement of the axes of any machine. In the same way, strengths and weaknesses of measurement methods and optimization techniques depending on the space available to place the measurement system are presented. These studies provide the most appropriate strategies to verify each machine tool taking into consideration its configuration and its available work space.

  1. Volumetric Verification of Multiaxis Machine Tool Using Laser Tracker

    PubMed Central

    Aguilar, Juan José

    2014-01-01

    This paper aims to present a method of volumetric verification in machine tools with linear and rotary axes using a laser tracker. Beyond a method for a particular machine, it presents a methodology that can be used in any machine type. Along this paper, the schema and kinematic model of a machine with three axes of movement, two linear and one rotational axes, including the measurement system and the nominal rotation matrix of the rotational axis are presented. Using this, the machine tool volumetric error is obtained and nonlinear optimization techniques are employed to improve the accuracy of the machine tool. The verification provides a mathematical, not physical, compensation, in less time than other methods of verification by means of the indirect measurement of geometric errors of the machine from the linear and rotary axes. This paper presents an extensive study about the appropriateness and drawbacks of the regression function employed depending on the types of movement of the axes of any machine. In the same way, strengths and weaknesses of measurement methods and optimization techniques depending on the space available to place the measurement system are presented. These studies provide the most appropriate strategies to verify each machine tool taking into consideration its configuration and its available work space. PMID:25202744

  2. Single-Chip CMUT-on-CMOS Front-End System for Real-Time Volumetric IVUS and ICE Imaging

    PubMed Central

    Gurun, Gokce; Tekes, Coskun; Zahorian, Jaime; Xu, Toby; Satir, Sarp; Karaman, Mustafa; Hasler, Jennifer; Degertekin, F. Levent

    2014-01-01

    Intravascular ultrasound (IVUS) and intracardiac echography (ICE) catheters with real-time volumetric ultrasound imaging capability can provide unique benefits to many interventional procedures used in the diagnosis and treatment of coronary and structural heart diseases. Integration of CMUT arrays with front-end electronics in single-chip configuration allows for implementation of such catheter probes with reduced interconnect complexity, miniaturization, and high mechanical flexibility. We implemented a single-chip forward-looking (FL) ultrasound imaging system by fabricating a 1.4-mm-diameter dual-ring CMUT array using CMUT-on-CMOS technology on a front-end IC implemented in 0.35-µm CMOS process. The dual-ring array has 56 transmit elements and 48 receive elements on two separate concentric annular rings. The IC incorporates a 25-V pulser for each transmitter and a low-noise capacitive transimpedance amplifier (TIA) for each receiver, along with digital control and smart power management. The final shape of the silicon chip is a 1.5-mm-diameter donut with a 430-µm center hole for a guide wire. The overall front-end system requires only 13 external connections and provides 4 parallel RF outputs while consuming an average power of 20 mW. We measured RF A-scans from the integrated single-chip array which show full functionality at 20.1 MHz with 43% fractional bandwidth. We also tested and demonstrated the image quality of the system on a wire phantom and an ex-vivo chicken heart sample. The measured axial and lateral point resolutions are 92 µm and 251 µm, respectively. We successfully acquired volumetric imaging data from the ex-vivo chicken heart with 60 frames per second without any signal averaging. These demonstrative results indicate that single-chip CMUT-on-CMOS systems have the potential to produce real-time volumetric images with image quality and speed suitable for catheter based clinical applications. PMID:24474131

  3. Single-chip CMUT-on-CMOS front-end system for real-time volumetric IVUS and ICE imaging.

    PubMed

    Gurun, Gokce; Tekes, Coskun; Zahorian, Jaime; Xu, Toby; Satir, Sarp; Karaman, Mustafa; Hasler, Jennifer; Degertekin, F Levent

    2014-02-01

    Intravascular ultrasound (IVUS) and intracardiac echography (ICE) catheters with real-time volumetric ultrasound imaging capability can provide unique benefits to many interventional procedures used in the diagnosis and treatment of coronary and structural heart diseases. Integration of capacitive micromachined ultrasonic transducer (CMUT) arrays with front-end electronics in single-chip configuration allows for implementation of such catheter probes with reduced interconnect complexity, miniaturization, and high mechanical flexibility. We implemented a single-chip forward-looking (FL) ultrasound imaging system by fabricating a 1.4-mm-diameter dual-ring CMUT array using CMUT-on-CMOS technology on a front-end IC implemented in 0.35-μm CMOS process. The dual-ring array has 56 transmit elements and 48 receive elements on two separate concentric annular rings. The IC incorporates a 25-V pulser for each transmitter and a low-noise capacitive transimpedance amplifier (TIA) for each receiver, along with digital control and smart power management. The final shape of the silicon chip is a 1.5-mm-diameter donut with a 430-μm center hole for a guide wire. The overall front-end system requires only 13 external connections and provides 4 parallel RF outputs while consuming an average power of 20 mW. We measured RF A-scans from the integrated single- chip array which show full functionality at 20.1 MHz with 43% fractional bandwidth. We also tested and demonstrated the image quality of the system on a wire phantom and an ex vivo chicken heart sample. The measured axial and lateral point resolutions are 92 μm and 251 μm, respectively. We successfully acquired volumetric imaging data from the ex vivo chicken heart at 60 frames per second without any signal averaging. These demonstrative results indicate that single-chip CMUT-on-CMOS systems have the potential to produce realtime volumetric images with image quality and speed suitable for catheter-based clinical applications.

  4. Multi-frequency Axial Transmission Bone Ultrasonometer

    PubMed Central

    Tatarinov, Alexey; Egorov, Vladimir; Sarvazyan, Noune; Sarvazyan, Armen

    2014-01-01

    The last decade has seen a surge in the development of axial transmission QUS (Quantitative UltraSound) technologies for the assessment of long bones using various modes of acoustic waves. The condition of cortical bones and the development of osteoporosis are determined by numerous mechanical, micro-structural, and geometrical or macro-structural bone properties like hardness, porosity and cortical thickness. Such complex manifestations of osteoporosis require the evaluation of multiple parameters with different sensitivities to the various properties of bone that are affected by the disease. This objective may be achieved by using a multi-frequency ultrasonic examination The ratio of the acoustic wavelength to the cortical thickness can be changed by varying the frequency of the ultrasonic pulse propagating through the long bone that results in the change in composition of the induced wave comprised of a set of numerous modes of guided, longitudinal, and surface acoustic waves. The multi-frequency axial transmission QUS method developed at Artann Laboratories (Trenton, NJ) is implemented in the Bone Ultrasonic Scanner (BUSS). In the current version of the BUSS, a train of ultrasonic pulses with 60, 100, 400, 800, and 1200 kHz frequencies is used. The developed technology was tested on a variety of bone phantoms simulating normal, osteopenic, and osteoporotic bones. The results of this study confirm the feasibility of the multi-frequency approach for the assessment of the processes leading to osteoporosis. PMID:24206675

  5. Multi-frequency axial transmission bone ultrasonometer.

    PubMed

    Tatarinov, Alexey; Egorov, Vladimir; Sarvazyan, Noune; Sarvazyan, Armen

    2014-07-01

    The last decade has seen a surge in the development of axial transmission QUS (Quantitative UltraSound) technologies for the assessment of long bones using various modes of acoustic waves. The condition of cortical bones and the development of osteoporosis are determined by numerous mechanical, micro-structural, and geometrical or macro-structural bone properties like hardness, porosity and cortical thickness. Such complex manifestations of osteoporosis require the evaluation of multiple parameters with different sensitivities to the various properties of bone that are affected by the disease. This objective may be achieved by using a multi-frequency ultrasonic examination The ratio of the acoustic wavelength to the cortical thickness can be changed by varying the frequency of the ultrasonic pulse propagating through the long bone that results in the change in composition of the induced wave comprised of a set of numerous modes of guided, longitudinal, and surface acoustic waves. The multi-frequency axial transmission QUS method developed at Artann Laboratories (Trenton, NJ) is implemented in the Bone Ultrasonic Scanner (BUSS). In the current version of the BUSS, a train of ultrasonic pulses with 60, 100, 400, 800, and 1200 kHz frequencies is used. The developed technology was tested on a variety of bone phantoms simulating normal, osteopenic, and osteoporotic bones. The results of this study confirm the feasibility of the multi-frequency approach for the assessment of the processes leading to osteoporosis.

  6. Microbubbling by co-axial electrohydrodynamic atomization.

    PubMed

    Farook, U; Stride, E; Edirisinghe, M J; Moaleji, R

    2007-08-01

    The preparation of microbubble suspensions is an important feature of medical engineering research. Recently, co-axial electrohydrodynamic atomization was used in our laboratory for the first time to prepare microbubble suspensions. In this paper, using a model glycerol-air system, we investigate in detail the characteristics of this microbubbling process. Modes of microbubbling are elucidated with respect to applied voltage and liquid and air flow rates. Thus, a parametric plot is constructed to identify a liquid and gas flow rate regime, which allows continuous microbubbling. This map provides a basis for the selection of a suitable combination of liquid and gas flow rates particularly in relation to yield and bubble size. The mechanism of microbubbling in microfluidic systems is compared with that of microbubbling by co-axial electrohydrodynamic atomization to identify the advantages and the limiting factors of the latter. Stability of microbubbles prepared by this method in terms of variation of diameter as a function of time is compared with previous literature on the dissolution of microbubbles with an air core and suggests the need for further work to stabilize the bubbles.

  7. Modeling of an axial injection torch

    NASA Astrophysics Data System (ADS)

    Alves, L. L.; Álvarez, R.; Marques, L.; Rubio, S. J.; Rodero, A.; Quintero, M. C.

    2009-05-01

    This paper presents simulation results for a microwave (2.45GHz) plasma reactor, operated by an axial injection torch (AIT). The study gives a two-dimensional description of the AIT-reactor system, based on an electromagnetic model (that solves Maxwell's equations adopting a time-harmonic description, yielding the distribution of the electromagnetic fields and the average power absorbed by the plasma), and a hydrodynamic model (that solves the Navier-Stokes' equations for the flowing neutral gas, yielding the distribution of mass density, pressure, temperature, and velocities). Comparison between model results and experimental measurements reveal common variation trends, with changes in the reactor height, for the power reflected by the system, and yield a qualitative agreement for the axial profile of the gas rotational temperature. Model results, such as the power transmission coefficient and the gas temperature, are particularly dependent on the reactor dimensions, the electron density and temperature, and the gas input flow, which indicates that simulations can be used to provide general guidelines for device optimization.

  8. Axial vessel widening in arborescent monocots.

    PubMed

    Petit, Giai; DeClerck, Fabrice A J; Carrer, Marco; Anfodillo, Tommaso

    2014-02-01

    Dicotyledons have evolved a strategy to compensate for the increase in hydraulic resistance to water transport with height growth by widening xylem conduits downwards. In monocots, the accumulation of hydraulic resistance with height should be similar, but the absence of secondary growth represents a strong limitation for the maintenance of xylem hydraulic efficiency during ontogeny. The hydraulic architecture of monocots has been studied but it is unclear how monocots arrange their axial vascular structure during ontogeny to compensate for increases in height. We measured the vessel lumina and estimated the hydraulic diameter (Dh) at different heights along the stem of two arborescent monocots, Bactris gasipaes (Kunth) and Guadua angustifolia (Kunth). For the former, we also estimated the variation in Dh along the leaf rachis. Hydraulic diameter increased basally from the stem apex to the base with a scaling exponent (b) in the range of those reported for dicot trees (b = 0.22 in B. gasipaes; b = 0.31 and 0.23 in G. angustifolia). In B. gasipaes, vessels decrease in Dh from the stem's centre towards the periphery, an opposite pattern compared with dicot trees. Along the leaf rachis, a pattern of increasing Dh basally was also found (b = 0.13). The hydraulic design of the monocots studied revealed an axial pattern of xylem conduits similar to those evolved by dicots to compensate and minimize the negative effect of root-to-leaf length on hydrodynamic resistance to water flow.

  9. Pulsed Detonation Operation of an Axial Turbine

    NASA Astrophysics Data System (ADS)

    Munday, David; St. George, Andrew; Driscoll, Robert; Gutmark, Ephraim; Gas Dynamics and Propulsion Lab Team

    2013-11-01

    A detonation is by its nature a more thermodynamically efficient combustion mode than deflagration. Several attempts are underway to integrate detonating combustion into turbomachines in order to realize the increased efficiency available, save resources and reduce emissions. One approach to this challenge is to employ pulsed detonations as from pulsed detonation engines (PDEs) and use the pulsed outflow to drive a turbine. The difficulty with this approach is that turbines, especially the more efficient axial turbines suffer in efficiency when their inflow is pulsed. At present there is not even a commonly acknowledged turbine efficiency measure which works reasonably for a pulsed input. The present work investigates the efficiency of an axial turbine with pulsed flow. Initial tests are performed with non-combusting flow in order to study the influence of pulsation on the turbine performance. This cold flow will admit a broader range of instrumentation which can be inserted within the turbine. This allows time-resolved measure of the flow angles which have a pronounced effect on the turbine performance. Later tests with detonating inflow yield global measures and these are compared to the non-combusting results. Work sponsored by Innovative Scientific Solutions, Inc.

  10. Volumetric and two-dimensional image interpretation show different cognitive processes in learners.

    PubMed

    van der Gijp, Anouk; Ravesloot, Cécile J; van der Schaaf, Marieke F; van der Schaaf, Irene C; Huige, Josephine C B M; Vincken, Koen L; Ten Cate, Olle Th J; van Schaik, Jan P J

    2015-05-01

    In current practice, radiologists interpret digital images, including a substantial amount of volumetric images. We hypothesized that interpretation of a stack of a volumetric data set demands different skills than interpretation of two-dimensional (2D) cross-sectional images. This study aimed to investigate and compare knowledge and skills used for interpretation of volumetric versus 2D images. Twenty radiology clerks were asked to think out loud while reading four or five volumetric computed tomography (CT) images in stack mode and four or five 2D CT images. Cases were presented in a digital testing program allowing stack viewing of volumetric data sets and changing views and window settings. Thoughts verbalized by the participants were registered and coded by a framework of knowledge and skills concerning three components: perception, analysis, and synthesis. The components were subdivided into 16 discrete knowledge and skill elements. A within-subject analysis was performed to compare cognitive processes during volumetric image readings versus 2D cross-sectional image readings. Most utterances contained knowledge and skills concerning perception (46%). A smaller part involved synthesis (31%) and analysis (23%). More utterances regarded perception in volumetric image interpretation than in 2D image interpretation (Median 48% vs 35%; z = -3.9; P < .001). Synthesis was less prominent in volumetric than in 2D image interpretation (Median 28% vs 42%; z = -3.9; P < .001). No differences were found in analysis utterances. Cognitive processes in volumetric and 2D cross-sectional image interpretation differ substantially. Volumetric image interpretation draws predominantly on perceptual processes, whereas 2D image interpretation is mainly characterized by synthesis. The results encourage the use of volumetric images for teaching and testing perceptual skills. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  11. Elastic Buckling of Orthotropic Plates Under Varying Axial Stresses

    NASA Technical Reports Server (NTRS)

    Badir, Ashraf; Hu, Hurang; Diallo, Abdouramane

    1997-01-01

    The elastic buckling load of simply supported rectangular orthotropic plates subjected to a second degree parabolic variation of axial stresses in the longitudinal direction is calculated using analytical methods. The variation of axial stresses is equilibrated by nonuniform shear stresses along the plate edges and transverse normal stresses. The influence of the aspect ratio is examined, and the results are compared with plates subjected to uniform axial stresses.

  12. A technique to determine a desired preparation axial inclination.

    PubMed

    Parker, M Harry; Ivanhoe, John R; Blalock, John S; Frazier, Kevin B; Plummer, Kevin D

    2003-10-01

    The guidelines recommended in the literature for the convergence angle of a crown preparation vary from 3 to 24 degrees. There is a lack of guidelines on techniques to achieve a specific axial inclination. The purpose of this article was to present a practical technique, with a diamond rotary cutting instrument of known axial inclination, to determine the diamond rotary cutting instrument angulations required to achieve the desired axial inclination of a preparation.

  13. U(1) axial charge in the chiral limit

    NASA Astrophysics Data System (ADS)

    Ji, Xiangdong

    1990-07-01

    The U(1) axial-vector form factor is studied using an unsubtracted dispersion relation. The associated axial charge is shown to be analytic in quark masses in the chiral limit although individual terms in the Cheng-Li separation exhibit large isospin and flavor-SU(3) symmetry breaking. A new separation of the U(1) axial charge is proposed, based on the wave functions of the physical states entering in the spectral density.

  14. Volumetric evaluation of fat resorption after breast lipofilling.

    PubMed

    Ho Quoc, C; Taupin, T; Guérin, N; Delay, E

    2015-12-01

    The fat transfer or the lipofilling is a technique that had a major impact on the breast surgery results. We have been using this technique since 1998 as an adjuvant in breast reconstruction. The transferred fat is partially resorbed in the first three months after fat grafting. Literature shows that fat resorption varies from 30 to 80% and the experimental studies register a variation between 50 and 90%. The difficulty of the lipomodeling consists in anticipating the fat resorption rate in order to obtain breast symmetry. The purpose of this article is to evaluate the resorption rate of the transferred fat in the reconstructed breast by means of volumetric imaging 3 months after fat grafting. A prospective study was undertaken including breast reconstructions with total autologous latissimus dorsi. All the surgical procedures have been done by the same surgeon (1st author). It focused on the second stage of breast reconstruction: the lipofilling. We registered the average harvested volumes, the volumes obtained after centrifugation and the transferred volumes for every reconstructed breast. The intramuscular volume in the reconstructed breast was measured by volumetric imaging on the third day after lipofilling (D3) and three months after lipofilling (M3). The volumetry was performed by using an after treatment console SIEMENS (SOMATOM definition AS 2*64 barettes). The average intramuscular volume was registered at D3 and M3. The average volume difference was calculated in order to obtain the exact resorption rate. This prospective study was undertaken on 32 reconstructed breasts by total autologous latissimus dorsi flap. The average age was 52 years, the average BMI was 24.7 kg/m(2). The average harvested fat volume for the breast lipofilling was 560 cc and the volume obtained after centrifugation was evaluated at about 371 cc, the average fat volume transferred being 291 cc. The volumetric study showed that intramuscular volume at D3 was measured at 284 cc and

  15. The efficiency of a volumetric alcohol tax in Australia.

    PubMed

    Byrnes, Joshua; Petrie, Dennis J; Doran, Christopher M; Shakeshaft, Anthony

    2012-01-01

    In Australia and elsewhere, fiscal measures such as alcohol taxation are a commonly used intervention and cost-effective strategy to reduce alcohol consumption and associated harm. However, alcohol taxation policies distort the market for alcohol, specifically increasing the marginal cost of alcohol. It is proposed that a volumetric tax, which taxes alcohol equally across all beverage types, is less distortive of consumer preferences and more efficient at reducing alcohol consumption than the current Australian tax model, where taxes are charged at varying amounts per litre of pure alcohol, depending on the beverage type. This paper quantifies the effect of four different alcohol taxation systems, relative to the current Australian system: two different types of volumetric taxation (deadweight loss neutral and tax revenue neutral); the recent strategy trialled in Australia of increasing the tax only on ready-to-drink alcoholic beverages (i.e. premixed spirits); and a tiered tax system, which may be more politically acceptable. A partial equilibrium approach was used to measure taxation revenue, consumer welfare and consumption in alcohol markets. Estimates of taxation revenue, consumer welfare and consumption were first calculated for 2008 and then compared with the four scenarios considered. Relative to the previous alcohol taxation scheme in Australia, the taxation strategy that increased the tax solely on ready-to-drink alcoholic beverages increased taxation revenue by 479 million Australian dollars ($A), reduced pure alcohol consumption by 754 000 litres and increased the net deadweight loss of taxation by $A62 million. For a tax-neutral approach, for the same level of taxation revenue as is currently generated, a volumetric tax could substantially reduce the cost of taxation (as described by the net loss in consumer welfare) by $A177 million and reduce pure alcohol consumption by 4 68 000 litres. Under a deadweight loss-neutral scenario, for the same

  16. Rapid mapping of volumetric machine errors using distance measurements

    SciTech Connect

    Krulewich, D.A.

    1998-04-01

    This paper describes a relatively inexpensive, fast, and easy to execute approach to maping the volumetric errors of a machine tool, coordinate measuring machine, or robot. An error map is used to characterize a machine or to improve its accuracy by compensating for the systematic errors. The method consists of three steps: (1) models the relationship between volumetric error and the current state of the machine, (2) acquiring error data based on distance measurements throughout the work volume; and (3)fitting the error model using the nonlinear equation for the distance. The error model is formulated from the kinematic relationship among the six degrees of freedom of error an each moving axis. Expressing each parametric error as function of position each is combined to predict the error between the functional point and workpiece, also as a function of position. A series of distances between several fixed base locations and various functional points in the work volume is measured using a Laser Ball Bar (LBB). Each measured distance is a non-linear function dependent on the commanded location of the machine, the machine error, and the location of the base locations. Using the error model, the non-linear equation is solved producing a fit for the error model Also note that, given approximate distances between each pair of base locations, the exact base locations in the machine coordinate system determined during the non-linear filling procedure. Furthermore, with the use of 2048 more than three base locations, bias error in the measuring instrument can be removed The volumetric errors of three-axis commercial machining center have been mapped using this procedure. In this study, only errors associated with the nominal position of the machine were considered Other errors such as thermally induced and load induced errors were not considered although the mathematical model has the ability to account for these errors. Due to the proprietary nature of the projects we are

  17. Modular functional organisation of the axial locomotor system in salamanders.

    PubMed

    Cabelguen, Jean-Marie; Charrier, Vanessa; Mathou, Alexia

    2014-02-01

    Most investigations on tetrapod locomotion have been concerned with limb movements. However, there is compelling evidence that the axial musculoskeletal system contributes to important functions during locomotion. Adult salamanders offer a remarkable opportunity to examine these functions because these amphibians use axial undulations to propel themselves in both aquatic and terrestrial environments. In this article, we review the currently available biological data on axial functions during various locomotor modes in salamanders. We also present data showing the modular organisation of the neural networks that generate axial synergies during locomotion. The functional implication of this modular organisation is discussed.

  18. Motion and emotion: anxiety-axial connections in Parkinson's disease.

    PubMed

    Šumec, Rastislav; Rektorová, Irena; Jech, Robert; Menšíková, Kateřina; Roth, Jan; Růžička, Evžen; Sochorová, Dana; Dušek, Ladislav; Kaňovský, Petr; Rektor, Ivan; Pavlík, Tomáš; Filip, Pavel; Bareš, Martin

    2017-03-01

    Anxiety is a serious and frequent complication in Parkinson's disease (PD) that significantly affects the quality of life of patients. Multiple neuroanatomical, experimental, and clinical studies suggest its close association with axial disturbances. However, whether this relation applies for PD patients (commonly suffering from axial difficulties, such as balance and gait disturbance) has not been properly tested yet. The purpose of this study was to determine whether PD patients suffering from axial symptoms have higher levels of anxiety than others and to identify other factors associated with anxiety-axial connections. In this questionnaire study, 212 patients with PD were assessed by standardized scales, such as Hamilton Anxiety Scale, Montgomery-Asberg Depression Rating Scale, Montreal Cognitive Assessment, examining their mood and cognitive status. These data were correlated to dominant motor symptoms of these patients, such as tremor, rigidity, bradykinesia, and axial symptoms. Unlike other motor symptoms, only axial symptoms showed to be significantly related to higher levels of anxiety. The patients suffering from anxiety and axial problems have also shown significantly higher depression levels. Axial disturbances are related to higher anxiety levels in PD patients. It is crucial to pay high attention to symptoms of anxiety in patients having postural instability or gait disorder. Further clinical studies are desirable to investigate new, practical implications of anxiety-axial connection to provide complex management options of these serious symptoms.

  19. Nuclear axial currents in chiral effective field theory

    SciTech Connect

    Baroni, Alessandro; Girlanda, Luca; Pastore, Saori; Schiavilla, Rocco; Viviani, Michele

    2016-01-11

    Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory and accounts for cancellations between the contributions of irreducible diagrams and the contributions owing to nonstatic corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and conserved in the chiral limit, while the axial charge requires renormalization. As a result, a complete set of contact terms for the axial charge up to the relevant order in the power counting is constructed.

  20. Nuclear axial currents in chiral effective field theory

    DOE PAGES

    Baroni, Alessandro; Girlanda, Luca; Pastore, Saori; ...

    2016-01-11

    Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory and accounts for cancellations between the contributions of irreducible diagrams and the contributions owing to nonstatic corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and conserved in the chiral limit, while the axial charge requires renormalization. As a result, a complete set of contact terms for the axial charge up to the relevant order in the power countingmore » is constructed.« less

  1. Axially symmetric shapes with minimum wave drag

    NASA Technical Reports Server (NTRS)

    Heaslet, Max A; Fuller, Franklyn B

    1956-01-01

    The external wave drag of bodies of revolution moving at supersonic speeds can be expressed either in terms of the geometry of the body, or in terms of the body-simulating axial source distribution. For purposes of deriving optimum bodies under various given conditions, it is found that the second of the methods mentioned is the more tractable. By use of a quasi-cylindrical theory, that is, the boundary conditions are applied on the surface of a cylinder rather than on the body itself, the variational problems of the optimum bodies having prescribed volume or caliber are solved. The streamline variations of cross-sectional area and drags of the bodies are exhibited, and some numerical results are given.

  2. Axial flux machine, stator and fabrication method

    DOEpatents

    Carl, Ralph James

    2004-03-16

    An axial flux machine comprises: a soft magnetic composite stator extension positioned in parallel with a rotor disk and having slots; soft magnetic composite pole pieces attached to the stator extension and facing a permanent magnet on the rotor disk, each comprising a protrusion situated within a respective one of the slots, each protrusion shaped so as to facilitate orientation of the respective pole piece with respect to the stator extension; electrical coils, each wrapped around a respective one of the pole pieces. In another embodiment the soft magnetic composite pole pieces each comprise a base portion around with the electrical coils are wound and a trapezoidal shield portion a plurality of heights with a first height in a first region being longer than a second height in a second region, the second region being closer to a pole-to-pole gap than the first region.

  3. Temperature gradient formation while axial gas compression

    NASA Astrophysics Data System (ADS)

    Geyko, V. I.; Fisch, N. J.

    2015-11-01

    A spinning gas in equilibrium has a rotation-dependent heat capacity. However, as equilibrium is approached, such as after sudden heating, significant variations in temperature appear. Surprisingly, when fast axial compression or instantaneous gas heating occurs, the temperature does not grow homogeneously in radial direction, but instead has a gradient towards to the maximum of potential energy of external or self potential. The gradient monotonically grows with compression rate and the amplitude of the potential. The gradient builds up due to change of equilibrium density distribution, yet, not due to acoustic waves created by the compression. This result was checked in numerical simulations for particles in an external constant gravitational potential and also for rotating gas in the cylinder with perfect slip boundary conditions on the walls. This work was supported by the U.S. Defense Threat Reduction Agency, and by the NNSA SSAA Program through DOE Research Grant No. DE-FG52-08NA28553.

  4. Axially symmetric static sources of gravitational field

    NASA Astrophysics Data System (ADS)

    Hernandez-Pastora, J. L.; Herrera, L.; Martin, J.

    2016-12-01

    A general procedure to find static and axially symmetric, interior solutions to the Einstein equations is presented. All the so obtained solutions, verify the energy conditions for a wide range of values of the parameters, and match smoothly to some exterior solution of the Weyl family, thereby representing globally regular models describing non-spherical sources of gravitational field. In the spherically symmetric limit, all our models converge to the well known incompressible perfect fluid solution. The key stone of our approach is based on an ansatz allowing to define the interior metric in terms of the exterior metric functions evaluated at the boundary source. Some particular sources are obtained, and the physical variables of the energy-momentum tensor are calculated explicitly, as well as the geometry of the source in terms of the relativistic multipole moments. The total mass of different configurations is also calculated, it is shown to be equal to the monopole of the exterior solution.

  5. Prismatic effect in axially symmetric spectacle lenses.

    PubMed

    Flores, Jose Ramon

    2009-08-01

    The purpose of this article is to compare different approximate formulas to compute the prismatic effect in axially symmetric spectacle lenses. Gaussian formulas to calculate the prismatic effect are derived, for thick and thin lenses, and for near and far vision. The results from these formulas, as well as other taken from the literature, are compared with the exact results. None of the studied approximations provides the most accurate results in all circumstances. The Gaussian formula for thick lenses could be considered globally the most accurate, both in near vision and far vision. However, it is notably more difficult to use than the traditional Prentice rule, because it is mathematically more complex, and needs several additional lens parameters.

  6. Hierarchical tapered bar elements undergoing axial deformation

    NASA Technical Reports Server (NTRS)

    Ganesan, N.; Thampi, S. K.

    1992-01-01

    A method is described to model the dynamics of tapered axial bars of various cross sections based on the well-known Craig/Bampton component mode synthesis technique. This element is formed in terms of the static constraint modes and interface restrained normal modes. This is in contrast with the finite elements as implemented in NASTRAN where the interface restrained normal modes are neglected. These normal modes are in terms of Bessel functions. Restoration of a few of these modes leads to higher accuracy with fewer generalized coordinates. The proposed models are hierarchical so that all lower order element matrices are embedded in higher order element matrices. The advantages of this formulation compared to standard NASTRAN truss element formulation are demonstrated through simple numerical examples.

  7. Aerodynamics of advanced axial-flow turbomachinery

    NASA Technical Reports Server (NTRS)

    Serovy, G. K.; Kavanagh, P.; Kiishi, T. H.

    1980-01-01

    A multi-task research program on aerodynamic problems in advanced axial-flow turbomachine configurations was carried out at Iowa State University. The elements of this program were intended to contribute directly to the improvement of compressor, fan, and turbine design methods. Experimental efforts in intra-passage flow pattern measurements, unsteady blade row interaction, and control of secondary flow are included, along with computational work on inviscid-viscous interaction blade passage flow techniques. This final report summarizes the results of this program and indicates directions which might be taken in following up these results in future work. In a separate task a study was made of existing turbomachinery research programs and facilities in universities located in the United States. Some potentially significant research topics are discussed which might be successfully attacked in the university atmosphere.

  8. Dark energy and collapsing axial system

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Manzoor, Rubab

    This paper investigates the effects of dark source term on the dissipative axially symmetric collapse by taking self-interacting Brans-Dicke (SBD) gravity as a dark energy (DE) candidate. We discuss physically feasible energy source of the model and formulate all the dynamical variables as well as structure scalars. It is found that the dark source term is one of the source of anisotropy and dissipation in the system. Further, we obtain structure scalars in this background. In order to discuss factors describing dissipative collapse, we develop equations related to the evolution of dynamical variables, heat transport equation as well as super-Poynting vector. We conclude that the thermodynamics of the collapse, evolution of kinematical terms (like expansion scalar, shear and vorticity) and inhomogeneity are affected by dark source term. Finally, we study the existence of radiation having repulsive gravitational nature in this collapse scenario.

  9. Buckling of cylindrical panels under axial compression

    NASA Technical Reports Server (NTRS)

    Sobel, L. H.; Weller, T.; Agarwal, B. L.

    1976-01-01

    This paper investigates the effects of boundary conditions and panel width on the axially compressive buckling behavior of unstiffened, isotropic, circular cylindrical panels. Numerical results are presented for eight different sets of boundary conditions along the straight edges of the panels. For all sets of boundary conditions except one (SS1), the results show that the panel buckling loads monotonically approach the complete cylinder buckling load from above as the panel width is increased. Low buckling loads, sometimes less than half the complete cylinder buckling load, are found for simply supported panels with free in-plane edge displacements (SS1). It is observed that the prevention of circumferential edge displacement is the most important in-plane boundary condition from the point of view of increasing the buckling load; and that the prevention of edge rotation in the circumferential direction also significantly increases the buckling load.

  10. Optimization approaches to volumetric modulated arc therapy planning.

    PubMed

    Unkelbach, Jan; Bortfeld, Thomas; Craft, David; Alber, Markus; Bangert, Mark; Bokrantz, Rasmus; Chen, Danny; Li, Ruijiang; Xing, Lei; Men, Chunhua; Nill, Simeon; Papp, Dávid; Romeijn, Edwin; Salari, Ehsan

    2015-03-01

    Volumetric modulated arc therapy (VMAT) has found widespread clinical application in recent years. A large number of treatment planning studies have evaluated the potential for VMAT for different disease sites based on the currently available commercial implementations of VMAT planning. In contrast, literature on the underlying mathematical optimization methods used in treatment planning is scarce. VMAT planning represents a challenging large scale optimization problem. In contrast to fluence map optimization in intensity-modulated radiotherapy planning for static beams, VMAT planning represents a nonconvex optimization problem. In this paper, the authors review the state-of-the-art in VMAT planning from an algorithmic perspective. Different approaches to VMAT optimization, including arc sequencing methods, extensions of direct aperture optimization, and direct optimization of leaf trajectories are reviewed. Their advantages and limitations are outlined and recommendations for improvements are discussed.

  11. Feature-driven data exploration for volumetric rendering.

    PubMed

    Woo, Insoo; Maciejewski, Ross; Gaither, Kelly P; Ebert, David S

    2012-10-01

    We have developed an intuitive method to semiautomatically explore volumetric data in a focus-region-guided or value-driven way using a user-defined ray through the 3D volume and contour lines in the region of interest. After selecting a point of interest from a 2D perspective, which defines a ray through the 3D volume, our method provides analytical tools to assist in narrowing the region of interest to a desired set of features. Feature layers are identified in a 1D scalar value profile with the ray and are used to define default rendering parameters, such as color and opacity mappings, and locate the center of the region of interest. Contour lines are generated based on the feature layer level sets within interactively selected slices of the focus region. Finally, we utilize feature-preserving filters and demonstrate the applicability of our scheme to noisy data.

  12. Volumetric properties of water/AOT/isooctane microemulsions.

    PubMed

    Du, Changfei; He, Wei; Yin, Tianxiang; Shen, Weiguo

    2014-12-23

    The densities of AOT/isooctane micelles and water/AOT/isooctane microemulsions with the molar ratios R of water to AOT being 2, 8, 10, 12, 16, 18, 20, 25, 30, and 40 were measured at 303.15 K. The apparent specific volumes of AOT and the quasi-component water/AOT at various concentrations were calculated and used to estimate the volumetric properties of AOT and water in the droplets and in the continuous oil phase, to discuss the interaction between the droplets, and to determine the critical micelle concentration and the critical microemulsion concentrations. A thermodynamic model was proposed to analysis the stability boundary of the microemulsion droplets, which confirms the maximum value of R being about 65 for the stable AOT/water/isooctane microemulsion droplets.

  13. Electrothermal energy conversion using electron gas volumetric change inside semiconductors

    SciTech Connect

    Yazawa, K.; Shakouri, A.

    2016-07-25

    We propose and analyze an electrothermal energy converter using volumetric changes in non-equilibrium electron gas inside semiconductors. The geometric concentration of electron gas under an electric field increases the effective pressure of the electrons, and then a barrier filters out cold electrons, acting like a valve. Nano- and micro-scale features enable hot electrons to arrive at the contact in a short enough time to avoid thermalization with the lattice. Key length and time scales, preliminary device geometry, and anticipated efficiency are estimated for electronic analogs of Otto and Brayton power generators and Joule-Thomson micro refrigerators on a chip. The power generators convert the energy of incident photons from the heat source to electrical current, and the refrigerator can reduce the temperature of electrons in a semiconductor device. The analytic calculations show that a large energy conversion efficiency or coefficient of performance may be possible.

  14. Semi-automatic volumetrics system to parcellate ROI on neocortex

    NASA Astrophysics Data System (ADS)

    Tan, Ou; Ichimiya, Tetsuya; Yasuno, Fumihiko; Suhara, Tetsuya

    2002-05-01

    A template-based and semi-automatic volumetrics system--BrainVol is build to divide the any given patient brain to neo-cortical and sub-cortical regions. The standard region is given as standard ROI drawn on a standard brain volume. After normalization between the standard MR image and the patient MR image, the sub-cortical ROIs' boundary are refined based on gray matter. The neo-cortical ROIs are refined by sulcus information that is semi-automatically marked on the patient brain. Then the segmentation is applied to 4D PET image of same patient for calculation of TAC (Time Activity Curve) by co-registration between MR and PET.

  15. Three-Dimensional Volumetric Restoration by Structural Fat Grafting

    PubMed Central

    Clauser, Luigi C.; Consorti, Giuseppe; Elia, Giovanni; Galié, Manlio; Tieghi, Riccardo

    2013-01-01

    The use of adipose tissue transfer for correction of maxillofacial defects was reported for the first time at the end of the 19th century. Structural fat grafting (SFG) was introduced as a way to improve facial esthetics and in recent years has evolved into applications in craniomaxillofacial reconstructive surgery. Several techniques have been proposed for harvesting and grafting the fat. However, owing to the damage of many adipocytes during these maneuvers, the results have not been satisfactory and have required several fat injection procedures for small corrections. The author's (L.C.) overview the application of SFG in the management of volumetric deficit in the craniomaxillofacial in patients treated with a long-term follow-up. PMID:24624259

  16. Optimization approaches to volumetric modulated arc therapy planning

    SciTech Connect

    Unkelbach, Jan Bortfeld, Thomas; Craft, David; Alber, Markus; Bangert, Mark; Bokrantz, Rasmus; Chen, Danny; Li, Ruijiang; Xing, Lei; Men, Chunhua; Nill, Simeon; Papp, Dávid; Romeijn, Edwin; Salari, Ehsan

    2015-03-15

    Volumetric modulated arc therapy (VMAT) has found widespread clinical application in recent years. A large number of treatment planning studies have evaluated the potential for VMAT for different disease sites based on the currently available commercial implementations of VMAT planning. In contrast, literature on the underlying mathematical optimization methods used in treatment planning is scarce. VMAT planning represents a challenging large scale optimization problem. In contrast to fluence map optimization in intensity-modulated radiotherapy planning for static beams, VMAT planning represents a nonconvex optimization problem. In this paper, the authors review the state-of-the-art in VMAT planning from an algorithmic perspective. Different approaches to VMAT optimization, including arc sequencing methods, extensions of direct aperture optimization, and direct optimization of leaf trajectories are reviewed. Their advantages and limitations are outlined and recommendations for improvements are discussed.

  17. Electrothermal energy conversion using electron gas volumetric change inside semiconductors

    NASA Astrophysics Data System (ADS)

    Yazawa, K.; Shakouri, A.

    2016-07-01

    We propose and analyze an electrothermal energy converter using volumetric changes in non-equilibrium electron gas inside semiconductors. The geometric concentration of electron gas under an electric field increases the effective pressure of the electrons, and then a barrier filters out cold electrons, acting like a valve. Nano- and micro-scale features enable hot electrons to arrive at the contact in a short enough time to avoid thermalization with the lattice. Key length and time scales, preliminary device geometry, and anticipated efficiency are estimated for electronic analogs of Otto and Brayton power generators and Joule-Thomson micro refrigerators on a chip. The power generators convert the energy of incident photons from the heat source to electrical current, and the refrigerator can reduce the temperature of electrons in a semiconductor device. The analytic calculations show that a large energy conversion efficiency or coefficient of performance may be possible.

  18. The effects of common medications on volumetric phallometry

    PubMed Central

    Lykins, Amy D.; Robinson, Jennifer J.; LeBlanc, Serge; Cantor, James M.

    2015-01-01

    Abstract Phallometry is a physiological measure of sexual response widely used for the assessment of paedophilia among sexual offenders. Although many medications decrease penile response sufficiently to interfere with sexual intercourse, it is unknown to what extent such medications might interfere with phallometric testing. In the current study, we utilized a naturalistic convenience sample of 1078 men who attended a clinic for assessment of sexual preferences, mostly related to sexual offence convictions. In the present analyses, we quantified the differences in penile response during phallometric assessment associated with taking a range of common medications. Participants on medication typically showed less penile output than participants not taking medications; however, differences were largely accounted for by age rather than by medication status. Though most medications were associated with decreases in penile responsivity during volumetric phallometric testing, such changes were small in absolute terms and appeared to be associated with ageing rather than with the medications themselves. PMID:26549976

  19. Volumetric leak detection in large underground storage tanks. Volume 1

    SciTech Connect

    Starr, J.W.; Wise, R.F.; Maresca, J.W.

    1991-08-01

    A set of experiments was conducted to determine whether volumetric leak detection system presently used to test underground storage tanks (USTs) up to 38,000 L (10,000 gal) in capacity could meet EPA's regulatory standards for tank tightness and automatic tank gauging systems when used to test tanks up to 190,000 L (50,000 gal) in capacity. The experiments, conducted on two partially filled 190,000-L (50,000-gal) USTs at Griffiss Air Force Base in upstate New York during late August 1990, showed that a system's performance in large tanks depends primarily on the accuracy of the temperature compensation, which is inversely proportional to the volume of product in the tank. Errors in temperature compensation that were negligible in tests in small tanks were important in large tanks. The experiments further suggest that a multiple-test strategy is also required.

  20. Quantitative volumetric Raman imaging of three dimensional cell cultures

    PubMed Central

    Kallepitis, Charalambos; Bergholt, Mads S.; Mazo, Manuel M.; Leonardo, Vincent; Skaalure, Stacey C.; Maynard, Stephanie A.; Stevens, Molly M.

    2017-01-01

    The ability to simultaneously image multiple biomolecules in biologically relevant three-dimensional (3D) cell culture environments would contribute greatly to the understanding of complex cellular mechanisms and cell–material interactions. Here, we present a computational framework for label-free quantitative volumetric Raman imaging (qVRI). We apply qVRI to a selection of biological systems: human pluripotent stem cells with their cardiac derivatives, monocytes and monocyte-derived macrophages in conventional cell culture systems and mesenchymal stem cells inside biomimetic hydrogels that supplied a 3D cell culture environment. We demonstrate visualization and quantification of fine details in cell shape, cytoplasm, nucleus, lipid bodies and cytoskeletal structures in 3D with unprecedented biomolecular specificity for vibrational microspectroscopy. PMID:28327660

  1. Quantitative volumetric Raman imaging of three dimensional cell cultures

    NASA Astrophysics Data System (ADS)

    Kallepitis, Charalambos; Bergholt, Mads S.; Mazo, Manuel M.; Leonardo, Vincent; Skaalure, Stacey C.; Maynard, Stephanie A.; Stevens, Molly M.

    2017-03-01

    The ability to simultaneously image multiple biomolecules in biologically relevant three-dimensional (3D) cell culture environments would contribute greatly to the understanding of complex cellular mechanisms and cell-material interactions. Here, we present a computational framework for label-free quantitative volumetric Raman imaging (qVRI). We apply qVRI to a selection of biological systems: human pluripotent stem cells with their cardiac derivatives, monocytes and monocyte-derived macrophages in conventional cell culture systems and mesenchymal stem cells inside biomimetic hydrogels that supplied a 3D cell culture environment. We demonstrate visualization and quantification of fine details in cell shape, cytoplasm, nucleus, lipid bodies and cytoskeletal structures in 3D with unprecedented biomolecular specificity for vibrational microspectroscopy.

  2. Volumetric sub-surface imaging using spectrally encoded endoscopy.

    PubMed

    Yelin, D; Bouma, B E; Tearney, G J

    2008-02-04

    Endoscopic imaging below tissue surfaces and through turbid media may provide improved diagnostic capabilities and visibility in surgical settings. Spectrally encoded endoscopy (SEE) is a recently developed method that utilizes a single optical fiber, miniature optics and a diffractive grating for high-speed imaging through small diameter, flexible endoscopic probes. SEE has also been shown to provide three-dimensional topological imaging capabilities. In this paper, we have configured SEE to additionally image beneath tissue surfaces, by increasing the system's sensitivity and acquiring the complex spectral density for each spectrally resolved point on the sample. In order to demonstrate the capability of SEE to obtain subsurface information, we have utilized the system to image a resolution target through intralipid solution, and conduct volumetric imaging of a mouse embryo and excised human middle-ear ossicles. Our results demonstrate that real-time subsurface imaging is possible with this miniature endoscopy technique.

  3. In vivo volumetric imaging of subcutaneous microvasculature by photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Hao F.; Maslov, Konstantin; Li, Meng-Lin; Stoica, George; Wang, Lihong V.

    2006-10-01

    Photoacoustic microscopy was developed to achieve volumetric imaging of the anatomy and functions of the subcutaneous microvasculature in both small animals and humans in vivo with high spatial resolution and high signal-to-background ratio. By following the skin contour in raster scanning, the ultrasonic transducer maintains focusing in the region of interest. Furthermore, off-focus lateral resolution is improved by using a synthetic-aperture focusing technique based on the virtual point detector concept. Structural images are acquired in both rats and humans, whereas functional images representing hemoglobin oxygen saturation are acquired in rats. After multiscale vesselness filtering, arterioles and venules in the image are separated based on the imaged oxygen saturation levels. Detailed structural information, such as vessel depth and spatial orientation, are revealed by volume rendering.

  4. Updated Volumetric Expansion Factors for K Basin Sludge During Storage

    SciTech Connect

    Schmidt, Andrew J. ); Delegard, Calvin H. )

    2003-03-14

    Sludge has accumulated in the K East (KE) and K West (KW) Basins at the Hanford Site. This sludge contains metallic uranium and uranium oxides that will corrode, hydrate, and generate and consume gases during containerized storage. From these corrosion reactions, two sludge expansion mechanisms can be expected: 1) expansion of the volume of the sludge solids from the generation of corrosion oxidation products that occupy more space than the starting-state sludge; and 2) expansion of the bulk sludge volume from the retention of hydrogen gas bubbles. This report provides a review and updated projections of the volumetric expansion occurring due to corrosion and gas retention during the containerized storage of K Basin sludge. New design and safety basis volume expansion values are provided for the following sludge streams: KW Floor, KW North Loadout Pit, KW canister, and fuel piece sludge.

  5. Volumetric dispenser for small particles from plural sources

    DOEpatents

    Bradley, R.A.; Miller, W.H.; Sease, J.D.

    1975-12-16

    Apparatus is described for rapidly and accurately dispensing measured volumes of small particles from a supply hopper. The apparatus includes an adjustable, vertically oriented measuring tube and orifice member defining the volume to be dispensed, a ball plug valve for selectively closing the bottom end of the orifice member, and a compression valve for selectively closing the top end of the measuring tube. A supply hopper is disposed above and in gravity flow communication with the measuring tube. Properly sequenced opening and closing of the two valves provides accurate volumetric discharge through the ball plug valve. A dispensing system is described wherein several appropriately sized measuring tubes, orifice members, and associated valves are arranged to operate contemporaneously to facilitate blending of different particles.

  6. Axially evoked postural reflexes: influence of task.

    PubMed

    Govender, Sendhil; Dennis, Danielle L; Colebatch, James G

    2015-01-01

    Postural reflexes were recorded in healthy subjects (n = 17) using brief axial accelerations and tap stimuli applied at the vertebra prominens (C7) and manubrium sterni. Short latency (SL) responses were recorded from the soleus, hamstrings and tibialis anterior muscles and expressed as a percentage of the background EMG prior to stimulus onset. In the majority of postural conditions tested, subjects were recorded standing erect and leaning forward with their feet together. The SL response was larger for soleus than for the hamstrings during standing (soleus vs hamstrings; 70.4 vs 28.1%), whereas the opposite occurred during kneeling (25.3 vs 127.3%). Concordant head and trunk accelerations produced larger SL responses than discordant accelerations for soleus and hamstrings, but the evoked excitatory response was independent of head direction and as expected for the direction of truncal acceleration. Postural reflexes for soleus and tibialis anterior were strongly affected by conditions that posed a significant threat to postural stability; stimulation at C7 was associated with significant SL enhancement for soleus during anterior lean while sternal stimulation showed SL enhancement for tibialis anterior during posterior lean. Cutaneous anaesthesia applied over the C7 stimulation site had no significant effect on EMG responses, nor did vision or surface type (rigid or compliant). This study provides further evidence that postural reflexes produced by brief axial accelerations are independent of cutaneous receptors, vestibular afferents and ankle proprioceptors, and demonstrates that postural tasks and truncal orientation significantly affect the evoked response, consistent with a role in stabilising posture.

  7. A novel computer algorithm allows for volumetric and cross-sectional area analysis of indirect decompression following transpsoas lumbar arthrodesis despite variations in MRI technique.

    PubMed

    Gates, Timothy A; Vasudevan, Ram R; Miller, Kai J; Stamatopoulou, Vasiliki; Mindea, Stefan A

    2014-03-01

    Many patients present for neurosurgical spine evaluation with MRI studies conducted at facilities outside of the treating medical center. These images often vary widely in technique, for example, variation in slice thickness, number of slices, and gantry angle. While these images may be sufficient in conjunction with a physical exam to make surgical evaluations, we have found they are often incapable of being used for objective post-operative volumetric comparisons. In order to overcome this, we created a computer program that compensates for these variations in MRI technique. For this study, we examined patients who had undergone outside MRI pre-operatively and were deemed appropriate for a lateral retroperitoneal transpsoas lumbar interbody arthrodesis procedure. Volumetric analysis was performed on sagittal and axial T2-weighted pre- and post-operative MRI. The percentage change of central canal volume and foraminal area was calculated for each level. The authors identified five levels with MRI sufficient for volumetric analysis and eight levels (16 foramina) sufficient for foraminal cross-sectional analysis. Through use of our computer algorithm, average central canal volume and foraminal cross-sectional area was calculated to increase by 32.8% and 67.6% respectively following the procedure. These results are consistent with previous study findings and support the idea that restoration of the anterior column via a lateral approach can result in significant indirect decompression of the neural elements. Additionally, the novel algorithm created and used for this study suggests that it can achieve quick measurement and comparison of MRI studies despite variations in pre- and post-operative technique.

  8. Marginal Space Deep Learning: Efficient Architecture for Volumetric Image Parsing.

    PubMed

    Ghesu, Florin C; Krubasik, Edward; Georgescu, Bogdan; Singh, Vivek; Yefeng Zheng; Hornegger, Joachim; Comaniciu, Dorin

    2016-05-01

    Robust and fast solutions for anatomical object detection and segmentation support the entire clinical workflow from diagnosis, patient stratification, therapy planning, intervention and follow-up. Current state-of-the-art techniques for parsing volumetric medical image data are typically based on machine learning methods that exploit large annotated image databases. Two main challenges need to be addressed, these are the efficiency in scanning high-dimensional parametric spaces and the need for representative image features which require significant efforts of manual engineering. We propose a pipeline for object detection and segmentation in the context of volumetric image parsing, solving a two-step learning problem: anatomical pose estimation and boundary delineation. For this task we introduce Marginal Space Deep Learning (MSDL), a novel framework exploiting both the strengths of efficient object parametrization in hierarchical marginal spaces and the automated feature design of Deep Learning (DL) network architectures. In the 3D context, the application of deep learning systems is limited by the very high complexity of the parametrization. More specifically 9 parameters are necessary to describe a restricted affine transformation in 3D, resulting in a prohibitive amount of billions of scanning hypotheses. The mechanism of marginal space learning provides excellent run-time performance by learning classifiers in clustered, high-probability regions in spaces of gradually increasing dimensionality. To further increase computational efficiency and robustness, in our system we learn sparse adaptive data sampling patterns that automatically capture the structure of the input. Given the object localization, we propose a DL-based active shape model to estimate the non-rigid object boundary. Experimental results are presented on the aortic valve in ultrasound using an extensive dataset of 2891 volumes from 869 patients, showing significant improvements of up to 45

  9. Quantitative volumetric breast density estimation using phase contrast mammography

    NASA Astrophysics Data System (ADS)

    Wang, Zhentian; Hauser, Nik; Kubik-Huch, Rahel A.; D'Isidoro, Fabio; Stampanoni, Marco

    2015-05-01

    Phase contrast mammography using a grating interferometer is an emerging technology for breast imaging. It provides complementary information to the conventional absorption-based methods. Additional diagnostic values could be further obtained by retrieving quantitative information from the three physical signals (absorption, differential phase and small-angle scattering) yielded simultaneously. We report a non-parametric quantitative volumetric breast density estimation method by exploiting the ratio (dubbed the R value) of the absorption signal to the small-angle scattering signal. The R value is used to determine breast composition and the volumetric breast density (VBD) of the whole breast is obtained analytically by deducing the relationship between the R value and the pixel-wise breast density. The proposed method is tested by a phantom study and a group of 27 mastectomy samples. In the clinical evaluation, the estimated VBD values from both cranio-caudal (CC) and anterior-posterior (AP) views are compared with the ACR scores given by radiologists to the pre-surgical mammograms. The results show that the estimated VBD results using the proposed method are consistent with the pre-surgical ACR scores, indicating the effectiveness of this method in breast density estimation. A positive correlation is found between the estimated VBD and the diagnostic ACR score for both the CC view (p=0.033 ) and AP view (p=0.001 ). A linear regression between the results of the CC view and AP view showed a correlation coefficient γ = 0.77, which indicates the robustness of the proposed method and the quantitative character of the additional information obtained with our approach.

  10. The volumetric rate of superluminous supernovae at z ˜ 1

    NASA Astrophysics Data System (ADS)

    Prajs, S.; Sullivan, M.; Smith, M.; Levan, A.; Karpenka, N. V.; Edwards, T. D. P.; Walker, C. R.; Wolf, W. M.; Balland, C.; Carlberg, R.; Howell, D. A.; Lidman, C.; Pain, R.; Pritchet, C.; Ruhlmann-Kleider, V.

    2017-01-01

    We present a measurement of the volumetric rate of superluminous supernovae (SLSNe) at z ˜ 1.0, measured using archival data from the first four years of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We develop a method for the photometric classification of SLSNe to construct our sample. Our sample includes two previously spectroscopically identified objects, and a further new candidate selected using our classification technique. We use the point-source recovery efficiencies from Perrett et al. and a Monte Carlo approach to calculate the rate based on our SLSN sample. We find that the three identified SLSNe from SNLS give a rate of 91^{+76}_{-36} SNe yr-1 Gpc-3 at a volume-weighted redshift of z = 1.13. This is equivalent to 2.2^{+1.8}_{-0.9}× 10^{-4} of the volumetric core-collapse supernova rate at the same redshift. When combined with other rate measurements from the literature, we show that the rate of SLSNe increases with redshift in a manner consistent with that of the cosmic star formation history. We also estimate the rate of ultra-long gamma-ray bursts based on the events discovered by the Swift satellite, and show that it is comparable to the rate of SLSNe, providing further evidence of a possible connection between these two classes of events. We also examine the host galaxies of the SLSNe discovered in SNLS, and find them to be consistent with the stellar-mass distribution of other published samples of SLSNe.

  11. A miniature real-time volumetric ultrasound imaging system

    NASA Astrophysics Data System (ADS)

    Wygant, Ira O.; Yeh, David T.; Zhuang, Xuefeng; Nikoozadeh, Amin; Oralkan, Omer; Ergun, Arif S.; Karaman, Mustafa; Khuri-Yakub, Butrus T.

    2005-04-01

    Progress made in the development of a miniature real-time volumetric ultrasound imaging system is presented. This system is targeted for use in a 5-mm endoscopic channel and will provide real-time, 30-mm deep, volumetric images. It is being developed as a clinically useful device, to demonstrate a means of integrating the front-end electronics with the transducer array, and to demonstrate the advantages of the capacitive micromachined ultrasonic transducer (CMUT) technology for medical imaging. Presented here is the progress made towards the initial implementation of this system, which is based on a two-dimensional, 16x16 CMUT array. Each CMUT element is 250 um by 250 um and has a 5 MHz center frequency. The elements are connected to bond pads on the back side of the array with 400-um long through-wafer interconnects. The transducer array is flip-chip bonded to a custom-designed integrated circuit that comprises the front-end electronics. The result is that each transducer element is connected to a dedicated pulser and low-noise preamplifier. The pulser generates 25-V, 100-ns wide, unipolar pulses. The preamplifier has an approximate transimpedance gain of 500 kOhm and 3-dB bandwidth of 10 MHz. In the first implementation of the system, one element at a time can be selected for transmit and receive and thus synthetic aperture images can be generated. In future implementations, 16 channels will be active at a given time. These channels will connect to an FPGA-based data acquisition system for real-time image reconstruction.

  12. A Comparison of Substantia Nigra T1 Hyperintensity in Parkinson's Disease Dementia, Alzheimer's Disease and Age-Matched Controls: Volumetric Analysis of Neuromelanin Imaging

    PubMed Central

    Park, Ju-Yeon; Yun, Won-Sung; Jeon, Ji Yeong; Moon, Yeon Sil; Kim, Heejin; Kwak, Ki-Chang; Lee, Jong-Min; Han, Seol-Heui

    2016-01-01

    Objective Neuromelanin loss of substantia nigra (SN) can be visualized as a T1 signal reduction on T1-weighted high-resolution imaging. We investigated whether volumetric analysis of T1 hyperintensity for SN could be used to differentiate between Parkinson's disease dementia (PDD), Alzheimer's disease (AD) and age-matched controls. Materials and Methods This retrospective study enrolled 10 patients with PDD, 18 patients with AD, and 13 age-matched healthy elderly controls. MR imaging was performed at 3 tesla. To measure the T1 hyperintense area of SN, we obtained an axial thin section high-resolution T1-weighted fast spin echo sequence. The volumes of interest for the T1 hyperintense SN were drawn onto heavily T1-weighted FSE sequences through midbrain level, using the MIPAV software. The measurement differences were tested using the Kruskal-Wallis test followed by a post hoc comparison. Results A comparison of the three groups showed significant differences in terms of volume of T1 hyperintensity (p < 0.001, Bonferroni corrected). The volume of T1 hyperintensity was significantly lower in PDD than in AD and normal controls (p < 0.005, Bonferroni corrected). However, the volume of T1 hyperintensity was not different between AD and normal controls (p = 0.136, Bonferroni corrected). Conclusion The volumetric measurement of the T1 hyperintensity of SN can be an imaging marker for evaluating neuromelanin loss in neurodegenerative diseases and a differential in PDD and AD cases. PMID:27587951

  13. Real-time GPU-accelerated processing and volumetric display for wide-field laser-scanning optical-resolution photoacoustic microscopy

    PubMed Central

    Kang, Heesung; Lee, Sang-Won; Lee, Eun-Soo; Kim, Se-Hwa; Lee, Tae Geol

    2015-01-01

    Fast signal processing and real-time displays are essential for practical imaging modality in various fields of applications. However, the imaging speed in optical-resolution photoacoustic microscopy (OR-PAM), in particular, depends on factors such as the pulse repetition rate of the laser, scanning method, field of view (FOV), and signal processing time. In the past, efforts to increase acquisition speed either focused on developing new scanning methods or using lasers with higher pulse repetition rates. However, high-speed signal processing is also important for real-time volumetric display in OR-PAM. In this study, we carried out parallel signal processing using a graphics processing unit (GPU) to enable fast signal processing and wide-field real-time displays in laser-scanning OR-PAM. The average total GPU processing time for a B-mode PAM image was approximately 1.35 ms at a display speed of 480 fps when the data samples were acquired with 736 (axial) × 500 (lateral) points/B-mode-frame at a pulse repetition rate of 300 kHz. In addition, we successfully displayed maximum amplitude projection images of a mouse’s ear as volumetric images with an FOV of 3 mm × 3 mm (500 × 500 pixels) at 1.02 s, corresponding to 0.98 fps. PMID:26713184

  14. Volumetric image reconstruction in a dental panoramic imaging system with a limited-angle zigzag scan geometry

    NASA Astrophysics Data System (ADS)

    Hong, Daeki; Cho, Hyosung; Lee, Seonhwa; Oh, Jieun; Lee, Minsik; Kim, Hyojeong; Je, Uikyu; Park, Yeonok; Choi, Sungil; Koo, Yangseo; Cho, Heemoon

    2013-01-01

    As a continuation of our dental imaging R&D, we have proposed a novel idea that is capable of implementing cost-effective, low-dose, volumetric image reconstruction directly onto a dental panoramic imaging system. In the proposed geometry, a linear-type panoramic detector is rotated 90° from the orientation for panoramic imaging and scanned along a limited-angle zigzag trajectory in the axial direction to cover the whole imaging volume thickness. We used an effective reconstruction algorithm based on the total-variation (TV) minimization approach for the proposed geometry and performed systematic simulation work to demonstrate the viability of our proposed approach and its effectiveness for three-dimensional (3D) dental X-ray imaging. We have successfully reconstructed images of substantially high image accuracy from the proposed geometry and evaluated the reconstruction quality by using an image similarity metric, the universal-quality index (UQI). We expect the proposed method to be applicable to developing a cost-effective, low-dose, all-in-one dental X-ray imaging system.

  15. Progressive Muscle Cell Delivery as a Solution for Volumetric Muscle Defect Repair

    PubMed Central

    Kim, Ji Hyun; Ko, In Kap; Atala, Anthony; Yoo, James J.

    2016-01-01

    Reconstructing functional volumetric tissue in vivo following implantation remains a critical challenge facing cell-based approaches. Several pre-vascularization approaches have been developed to increase cell viability following implantation. Structural and functional restoration was achieved in a preclinical rodent tissue defect; however, the approach used in this model fails to repair larger (>mm) defects as observed in a clinical setting. We propose an effective cell delivery system utilizing appropriate vascularization at the site of cell implantation that results in volumetric and functional tissue reconstruction. Our method of multiple cell injections in a progressive manner yielded improved cell survival and formed volumetric muscle tissues in an ectopic muscle site. In addition, this strategy supported the reconstruction of functional skeletal muscle tissue in a rodent volumetric muscle loss injury model. Results from our study suggest that our method may be used to repair volumetric tissue defects by overcoming diffusion limitations and facilitating adequate vascularization. PMID:27924941

  16. Global segmentation and curvature analysis of volumetric data sets using trivariate B-spline functions.

    PubMed

    Soldea, Octavian; Elber, Gershon; Rivlin, Ehud

    2006-02-01

    This paper presents a method to globally segment volumetric images into regions that contain convex or concave (elliptic) iso-surfaces, planar or cylindrical (parabolic) iso-surfaces, and volumetric regions with saddle-like (hyperbolic) iso-surfaces, regardless of the value of the iso-surface level. The proposed scheme relies on a novel approach to globally compute, bound, and analyze the Gaussian and mean curvatures of an entire volumetric data set, using a trivariate B-spline volumetric representation. This scheme derives a new differential scalar field for a given volumetric scalar field, which could easily be adapted to other differential properties. Moreover, this scheme can set the basis for more precise and accurate segmentation of data sets targeting the identification of primitive parts. Since the proposed scheme employs piecewise continuous functions, it is precise and insensitive to aliasing.

  17. Design, Implementation and Characterization of a Quantum-Dot-Based Volumetric Display

    NASA Astrophysics Data System (ADS)

    Hirayama, Ryuji; Naruse, Makoto; Nakayama, Hirotaka; Tate, Naoya; Shiraki, Atsushi; Kakue, Takashi; Shimobaba, Tomoyoshi; Ohtsu, Motoichi; Ito, Tomoyoshi

    2015-02-01

    In this study, we propose and experimentally demonstrate a volumetric display system based on quantum dots (QDs) embedded in a polymer substrate. Unlike conventional volumetric displays, our system does not require electrical wiring; thus, the heretofore unavoidable issue of occlusion is resolved because irradiation by external light supplies the energy to the light-emitting voxels formed by the QDs. By exploiting the intrinsic attributes of the QDs, the system offers ultrahigh definition and a wide range of colours for volumetric displays. In this paper, we discuss the design, implementation and characterization of the proposed volumetric display's first prototype. We developed an 8 × 8 × 8 display comprising two types of QDs. This display provides multicolour three-type two-dimensional patterns when viewed from different angles. The QD-based volumetric display provides a new way to represent images and could be applied in leisure and advertising industries, among others.

  18. Design, implementation and characterization of a quantum-dot-based volumetric display.

    PubMed

    Hirayama, Ryuji; Naruse, Makoto; Nakayama, Hirotaka; Tate, Naoya; Shiraki, Atsushi; Kakue, Takashi; Shimobaba, Tomoyoshi; Ohtsu, Motoichi; Ito, Tomoyoshi

    2015-02-16

    In this study, we propose and experimentally demonstrate a volumetric display system based on quantum dots (QDs) embedded in a polymer substrate. Unlike conventional volumetric displays, our system does not require electrical wiring; thus, the heretofore unavoidable issue of occlusion is resolved because irradiation by external light supplies the energy to the light-emitting voxels formed by the QDs. By exploiting the intrinsic attributes of the QDs, the system offers ultrahigh definition and a wide range of colours for volumetric displays. In this paper, we discuss the design, implementation and characterization of the proposed volumetric display's first prototype. We developed an 8 × 8 × 8 display comprising two types of QDs. This display provides multicolour three-type two-dimensional patterns when viewed from different angles. The QD-based volumetric display provides a new way to represent images and could be applied in leisure and advertising industries, among others.

  19. Enhanced volumetric visualization for real time 4D intraoperative ophthalmic swept-source OCT

    PubMed Central

    Viehland, Christian; Keller, Brenton; Carrasco-Zevallos, Oscar M.; Nankivil, Derek; Shen, Liangbo; Mangalesh, Shwetha; Viet, Du Tran; Kuo, Anthony N.; Toth, Cynthia A.; Izatt, Joseph A.

    2016-01-01

    Current-generation software for rendering volumetric OCT data sets based on ray casting results in volume visualizations with indistinct tissue features and sub-optimal depth perception. Recent developments in hand-held and microscope-integrated intrasurgical OCT designed for real-time volumetric imaging motivate development of rendering algorithms which are both visually appealing and fast enough to support real time rendering, potentially from multiple viewpoints for stereoscopic visualization. We report on an enhanced, real time, integrated volumetric rendering pipeline which incorporates high performance volumetric median and Gaussian filtering, boundary and feature enhancement, depth encoding, and lighting into a ray casting volume rendering model. We demonstrate this improved model implemented on graphics processing unit (GPU) hardware for real-time volumetric rendering of OCT data during tissue phantom and live human surgical imaging. We show that this rendering produces enhanced 3D visualizations of pathology and intraoperative maneuvers compared to standard ray casting. PMID:27231623

  20. High Volumetric Energy Density Hybrid Supercapacitors Based on Reduced Graphene Oxide Scrolls.

    PubMed

    Rani, Janardhanan R; Thangavel, Ranjith; Oh, Se-I; Woo, Jeong Min; Chandra Das, Nayan; Kim, So-Yeon; Lee, Yun-Sung; Jang, Jae-Hyung

    2017-07-12

    The low volumetric energy density of reduced graphene oxide (rGO)-based electrodes limits its application in commercial electrochemical energy storage devices that require high-performance energy storage capacities in small volumes. The volumetric energy density of rGO-based electrode materials is very low due to their low packing density. A supercapacitor with enhanced packing density and high volumetric energy density is fabricated using doped rGO scrolls (GFNSs) as the electrode material. The restacking of rGO sheets is successfully controlled through synthesizing the doped scroll structures while increasing the packing density. The fabricated cell exhibits an ultrahigh volumetric energy density of 49.66 Wh/L with excellent cycling stability (>10 000 cycles). This unique design strategy for the electrode material has significant potential for the future supercapacitors with high volumetric energy densities.

  1. New approach to a novel axially chiral ligand showing spontaneous enrichment of axial chirality.

    PubMed

    Hasegawa, Tomokuni; Omote, Masaaki; Sato, Kazuyuki; Ando, Akira; Kumadaki, Itsumaro

    2003-03-01

    We have synthesized novel axially chiral ligand with two chiral centers, (R)-(R)(2)- and (S)-(S)(2)-2,2'-bis(2,2,2-trifluoro-1-hydroxyethyl)biphenyl (1), which showed a high asymmetric induction when used as ligand. Here, another new approach to 1 by kinetic and thermodynamic resolution is presented which gave these ligands in a much shorter steps, in a higher yield, and in a higher enantiomeric excess.

  2. Volumetric brain analysis in neurosurgery: Part 3. Volumetric CT analysis as a predictor of seizure outcome following temporal lobectomy.

    PubMed

    Mandell, Jason G; Hill, Kenneth L; Nguyen, Dan T D; Moser, Kevin W; Harbaugh, Robert E; McInerney, James; Nsubuga, Brian Kaaya; Mugamba, John K; Johnson, Derek; Warf, Benjamin C; Boling, Warren; Webb, Andrew G; Schiff, Steven J

    2015-02-01

    The incidence of temporal lobe epilepsy (TLE) due to mesial temporal sclerosis (MTS) can be high in developing countries. Current diagnosis of MTS relies on structural MRI, which is generally unavailable in developing world settings. Given widespread effects on temporal lobe structure beyond hippocampal atrophy in TLE, the authors propose that CT volumetric analysis can be used in patient selection to help predict outcomes following resection. Ten pediatric patients received preoperative CT scans and temporal resections at the CURE Children's Hospital of Uganda. Engel classification of seizure control was determined 12 months postoperatively. Temporal lobe volumes were measured from CT and from normative MR images using the Cavalieri method. Whole brain and fluid volumes were measured using particle filter segmentation. Linear discrimination analysis (LDA) was used to classify seizure outcome by temporal lobe volumes and normalized brain volume. Epilepsy patients showed normal to small brain volumes and small temporal lobes bilaterally. A multivariate measure of the volume of each temporal lobe separated patients who were seizure free (Engel Class IA) from those with incomplete seizure control (Engel Class IB/IIB) with LDA (p<0.01). Temporal lobe volumes also separate normal subjects, patients with Engel Class IA outcomes, and patients with Class IB/IIB outcomes (p<0.01). Additionally, the authors demonstrated that age-normalized whole brain volume, in combination with temporal lobe volumes, may further improve outcome prediction (p<0.01). This study shows strong evidence that temporal lobe and brain volume can be predictive of seizure outcome following temporal lobe resection, and that volumetric CT analysis of the temporal lobe may be feasible in lieu of structural MRI when the latter is unavailable. Furthermore, since the authors' methods are modality independent, these findings suggest that temporal lobe and normative brain volumes may further be useful in the

  3. An Axial-Torsional, Thermomechanical Fatigue Testing Technique

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Bonacuse, Peter J.

    1995-01-01

    A technique for conducting strain-controlled, thermomechanical, axial-torsional fatigue tests on thin-walled tubular specimens was developed. Three waveforms of loading, namely, the axial strain waveform, the engineering shear strain waveform, and the temperature waveform were required in these tests. The phasing relationships between the mechanical strain waveforms and the temperature and axial strain waveforms were used to define a set of four axial-torsional, thermomechanical fatigue (AT-TMF) tests. Real-time test control (3 channels) and data acquisition (a minimum of 7 channels) were performed with a software program written in C language and executed on a personal computer. The AT-TMF testing technique was used to investigate the axial-torsional thermomechanical fatigue behavior of a cobalt-base superalloy, Haynes 188. The maximum and minimum temperatures selected for the AT-TMF tests were 760 and 316 C, respectively. Details of the testing system, calibration of the dynamic temperature profile of the thin-walled tubular specimen, thermal strain compensation technique, and test control and data acquisition schemes, are reported. The isothermal, axial, torsional, and in- and out-of-phase axial-torsional fatigue behaviors of Haynes 188 at 316 and 760 C were characterized in previous investigations. The cyclic deformation and fatigue behaviors of Haynes 188 in AT-TMF tests are compared to the previously reported isothermal axial-torsional behavior of this superalloy at the maximum and minimum temperatures.

  4. Axial resolution of a chromatic dispersion confocal microscopy

    NASA Astrophysics Data System (ADS)

    Garzon Reyes, Johnson; Meneses, J.; Plata, Arturo; Tribillon, Gilbert M.; Gharbi, Tijani

    2004-10-01

    An analysis of the axial resolution of a chromatic dispersion confocal microscopy is presented. The system is based on the principle of focus multiplexing by wavelength encoding due to a phase Fresnel lens. The axial resolution is related with the measure of the FWHM value of every spectral response.

  5. An Unbroken Axial-Vector Current Conservation Law

    NASA Astrophysics Data System (ADS)

    Sharafiddinov, Rasulkhozha S.

    2016-04-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space in which a neutrino is characterized by left as well as by right space-time coordinates. Therefore, it is not surprising that whatever the main purposes experiments about a quasielastic axial-vector mass say in favor of an axial-vector mirror Minkowski space-time.

  6. An Unbroken Axial-Vector Current Conservation Law

    NASA Astrophysics Data System (ADS)

    Sharafiddinov, Rasulkhozha S.

    2016-03-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space in which a neutrino is characterized by left as well as by right space-time coordinates. Therefore, it is not surprising that whatever the main purposes experiments about a quasielastic axial-vector mass say in favor of an axial-vector mirror Minkowski space-time.

  7. Study of a new airfoil used in reversible axial fans

    NASA Technical Reports Server (NTRS)

    Li, Chaojun; Wei, Baosuo; Gu, Chuangang

    1991-01-01

    The characteristics of the reverse ventilation of axial flow are analyzed. An s shaped airfoil with a double circular arc was tested in a wind tunnel. The experimental results showed that the characteristics of this new airfoil in reverse ventilation are the same as those in normal ventilation, and that this airfoil is better than the existing airfoils used on reversible axial fans.

  8. A new approach to radial and axial gauges

    NASA Astrophysics Data System (ADS)

    Weigert, Heribert; Heinz, Ulrich

    1992-03-01

    We develop a new path integral formulation of QCD in radial and axial gauges. This formalism yields free propagators which are free of gauge poles. We find that radial gauges are ghost free. In axial gauges ghosts cannot generally be excluded from the formalism due to the need to fix the residual gauge freedom.

  9. Development of a High Precision Axial 3-D PET for Brain Imaging

    NASA Astrophysics Data System (ADS)

    Bolle, E.; Braem, A.; Casella, C.; Chesi, E.; Clinthorne, N.; Cochran, E.; De Leo, R.; Dissertori, G.; Djambazov, L.; Honscheid, K.; Huh, S.; Johnson, I.; Joram, C.; Kagan, H.; Lacasta, C.; Lustermann, W.; Meddi, F.; Nappi, E.; Nessi-Tedaldi, F.; Oliver, J. F.; Pauss, F.; Rafecas, M.; Renker, D.; Rudge, A.; Schinzel, D.; Schneider, T.; Séguinot, J.; Smith, S.; Solevi, P.; Stapnes, S.; Vilardi, I.; Weilhammer, P.

    2009-12-01

    We describe a PET device based on a novel method to extract the coordinates of the interaction point of the 511keV γ rays from 100 mm long and thin LYSO (Lutetium Yttrium OxyorthoSilicate) scintillator bars, positioned axially in the tomograph. The coordinate along the hit crystal is measured by using a hodoscope of Wave Length Shifting (WLS) plastic strips mounted perpendicularly to each plane of scintillators. As photodetectors, new Geiger mode Avalanche PhotoDetectors (G-APDs) with integrated electronics are being used to detect both the hit crystal in a block (x and y coordinates) and the interaction point in the crystal (z coordinate) through the light escaping from the crystal and transmitted to the WLS strips. In this way, the γ interaction point can be determined with a spatial resolution of few cubic millimeters down to a minimum deposited energy of about 50 keV, resulting in a volumetric precision very close to the limits imposed by the physics of the positron annihilation. The method allows to increase the detection efficiency without affecting the spatial resolution by adding scintillator planes in the radial direction. A demonstrator scanner, based on two matrices of 8 × 6 LYS crystals and 312 WLS strips, slotted in between the crystals, is under construction. Preliminary results from the feasibility studies of the various components will be presented.

  10. Cerebrovascular dysfunction following subfailure axial stretch.

    PubMed

    Bell, E David; Donato, Anthony J; Monson, Kenneth L

    2017-01-01

    Cerebral blood vessels are vital to maintaining the health of the brain. Traumatic brain injury (TBI) commonly results in autoregulatory dysfunction and associated failure of cerebral vessels to maintain homeostasis in the brain. While post-injury changes to brain biochemistry are known to contribute to this dysfunction, tissue deformation may also directly alter vascular smooth muscle cell (SMC) function. As a first step toward understanding stretch-induced dysfunction, this study investigates the effect of overstretch on the contractile behavior of SMCs in middle cerebral arteries (MCAs). We hypothesized that vessel function is altered above a threshold of stretch and strain rate. Twenty-four MCAs from Sprague Dawley rats were tested. Following development of basal SMC tone, vessels were subjected to increasing levels of isosmotic extracellular potassium (K(+)). Samples were then subjected to an axial overstretch of either 1.2*λIV or 1.3*λIV at strain rates of 0.2 or 20s(-1). Following overstretch, SMC contractile behavior was measured again, both immediately and 60min after overstretch. Control vessels were subjected to the same protocol but without overstretch. SMC contractile behavior was characterized using both percent contraction (%C) relative to the fully dilated inner diameter and the K(+) dose required to evoke the half maximal contractile response (EC50). Control vessels exhibited increased sensitivity to K(+) in successive characterization tests, so all effects were quantified relative to the time-matched control response. Samples exhibited the typical biphasic response to extracellular K(+), dilating and contracting in response to small and large K(+) concentrations, respectively. As hypothesized, axial overstretch altered SMC contractile behavior, as seen in a decrease in %C for sub-maximal contractile K(+) doses (p<0.05) and an increase in EC50 (p<0.01), but only for the test group stretched rapidly to 1.3*λIV. While the change in %C was only

  11. Research on the effect of wear-ring clearances to the axial and radial force of a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhao, W. G.; Y He, M.; Qi, C. X.; Li, Y. B.

    2013-12-01

    Varying of the wear-ring clearance not only has a distinct effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump including the axial and radial forces. Comparing with the experimental studies, numerical simulation methods have some special advantages, such as the low cost, fast and high efficiency, and convenient to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study in recent years. In order to study the effect of wear-ring clearance on the force performance of the centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump with three variable styles of the wear-rings was simulated: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Comparing with the experiment, numerical results show a good agreement. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the axial force of the centrifugal pump, while has tiny effect on the radial force for all the conditions.

  12. Axial flow pump treatment during myocardial depression in calves: an invasive hemodynamic and echocardiographic tissue Doppler study.

    PubMed

    Hubbert, Laila; Peterzén, Bengt; Traff, Stefan; Janerot-Sjoberg, Birgitta; Ahn, Henrik

    2008-01-01

    The aim of this study was to investigate flow characteristics and myocardial function after implantation of an axial pump left ventricular assist device while varying afterload and during progressive myocardial depression. Ten calves were included, seven of which fulfilled the protocol. Invasive hemodynamic monitoring and echocardiography with color-coded systolic tissue Doppler velocity (TD velocity) were used during prepump conditions, at three different pump speeds, during modification of the systemic vascular resistance (SVR), and during increasing degrees of beta-blockade. The TD velocity decreased with the myocardial function whereas left ventricular size, fractional shortening, and pump speed did not correlate significantly with the TD velocity. The TD velocity correlated significantly with native stroke volume, heart rate, SVR and cardiac output but none of these alone could explain more than 20% of the changes in TD velocity. The axial flow pump studied is effective in unloading the severely depressed heart and has a high capacity for maintaining an adequate cardiac output, regardless of differing hemodynamic conditions, pump speed or decreasing LV function. Echocardiography with volumetric rendering and TD velocity imaging are valuable tools for monitoring and quantifying residual myocardial function during pump treatment.

  13. A synthetic diamond diode in volumetric modulated arc therapy dosimetry

    SciTech Connect

    Zani, Margherita; Bucciolini, Marta; Casati, Marta; Talamonti, Cinzia; Marinelli, Marco; Prestopino, Giuseppe; Tonnetti, Alessia; Verona-Rinati, Gianluca

    2013-09-15

    Purpose: The aim of this work is to investigate the behavior of a single crystal diamond diode (SCDD) for volumetric modulated arc therapy (VMAT) dose verifications. This delivery technique is one of the most severe test of a dosimeter performance due to the modulation of the dose rate achieved by simultaneously changing the velocity of the gantry and the position of the collimator leaves. The performed measurements with VMAT photon beams can therefore contribute to an overall global validation of the device to be used in dose distribution verifications.Methods: The SCDD response to 6 MVRX has been tested and compared with reference ionization chambers and treatment planning system (TPS) calculations in different experiments: (a) measurements of output factors for small field sizes (square fields of side ranging between 8 mm and 104 mm) by SCDD and A1SL ionization chamber; (b) angular dependence evaluation of the entire experimental set-up by SCDD, A1SL, and Farmer ionization chambers; and (c) acquisition of dose profiles for a VMAT treatment of a pulmonary disease in latero-lateral and gantry-target directions by SCDD and A1SL ionization chamber.Results: The output factors measured by SCDD favorably compare with the ones obtained by A1SL, whose response is affected by the lack of charged particle equilibrium and by averaging effect when small fields are involved. From the experiment on angular dependence, a good agreement is observed among the diamond diode, the ion chambers, and the TPS. In VMAT profiles, the absorbed doses measured by SCDD and A1SL compare well with the TPS calculated ones. An overall better agreement is observed in the case of the diamond dosimeter, which is also showing a better accuracy in terms of distance to agreement in the high gradient regions.Conclusions: Synthetic diamond diodes, whose performance were previously studied for conformal and IMRT radiotherapy techniques, were found to be suitable detectors also for dosimetric measurements

  14. Volumetric lean percentage measurement using dual energy mammography

    PubMed Central

    Ducote, Justin L.; Klopfer, Michael J.; Molloi, S.

    2011-01-01

    Purpose: Currently, there is no accepted standard for measuring breast density. Dual energy mammography, which has demonstrated accurate measurement in phantoms, has been proposed as one possible method. To examine the use of chemical analysis as a possible means to validate breast density measurements from dual energy mammography, a bovine tissue model was investigated. Known quantities of lean and adipose tissue were compared with composition values measured from dual energy images and chemical analysis. Methods: Theoretical simulations were performed to assess the impact variations in breast composition would have on measurement of breast density from a single calibration. Fourteen ex-vivo tissue samples composed of varying amounts of pure lean tissue and pure adipose tissue (lean percentage) from 0 to 100%, in increments of 10%, were imaged using dual energy mammography. This was followed by chemical analysis based on desiccation, trituration, and fat extraction with petroleum ether to determine water, lipid, and protein content. The volumetric lean percentage (VLP) as measured from images (VLPI) and as derived from chemical analysis data (VLPCA) were compared with the VLP calculated from measurements of sample mass with a scale (VLPM). Finally, data from the bovine tissue model in this study were compared to compositional data from a previous report of human tissue composition. Results: The results from simulation suggest a substantial impact on measuring breast density is likely due to changes in anatomical breast composition. VLPI was related to the VLPM by VLPI = 1.53 VLPM + 10.0 (r2>0.99). VLPCA was related to VLPM by VLPCA = 0.76 VLPM + 22.8 (r2>0.99). VLPI was related to VLPCA by VLPI = 2.00 VLPCA − 35.6 (r2>0.99). Bovine adipose tissue was shown to be very similar to human adipose tissue in terms of water, lipid, and protein content with RMS differences of 1.2%. Bovine lean tissue was shown to be very similar to human skeletal

  15. Widespread Volumetric Brain Changes following Tooth Loss in Female Mice

    PubMed Central

    Avivi-Arber, Limor; Seltzer, Ze'ev; Friedel, Miriam; Lerch, Jason P.; Moayedi, Massieh; Davis, Karen D.; Sessle, Barry J.

    2017-01-01

    Tooth loss is associated with altered sensory, motor, cognitive and emotional functions. These changes vary highly in the population and are accompanied by structural and functional changes in brain regions mediating these functions. It is unclear to what extent this variability in behavior and function is caused by genetic and/or environmental determinants and which brain regions undergo structural plasticity that mediates these changes. Thus, the overall goal of our research program is to identify genetic variants that control structural and functional plasticity following tooth loss. As a step toward this goal, here our aim was to determine whether structural magnetic resonance imaging (sMRI) is sensitive to detect quantifiable volumetric differences in the brains of mice of different genetic background receiving tooth extraction or sham operation. We used 67 adult female mice of 7 strains, comprising the A/J (A) and C57BL/6J (B) strains and a randomly selected sample of 5 of the 23 AXB-BXA strains (AXB1, AXB4, AXB24, BXA14, BXA24) that were produced from the A and B parental mice by recombinations and inbreeding. This panel of 25 inbred strains of genetically diverse inbred strains of mice is used for mapping chromosomal intervals throughout the genome that harbor candidate genes controlling the phenotypic variance of any trait under study. Under general anesthesia, 39 mice received extraction of 3 right maxillary molar teeth and 28 mice received sham operation. On post-extraction day 21, post-mortem whole-brain high-resolution sMRI was used to quantify the volume of 160 brain regions. Compared to sham operation, tooth extraction was associated with a significantly reduced regional and voxel-wise volumes of cortical brain regions involved in processing somatosensory, motor, cognitive and emotional functions, and increased volumes in subcortical sensorimotor and temporal limbic forebrain regions including the amygdala. Additionally, comparison of the 10 BXA14

  16. Volumetric breast density evaluation from ultrasound tomography images

    SciTech Connect

    Glide-Hurst, Carri K.; Duric, Neb; Littrup, Peter

    2008-09-15

    Previous ultrasound tomography work conducted by our group showed a direct correlation between measured sound speed and physical density in vitro, and increased in vivo sound speed with increasing mammographic density, a known risk factor for breast cancer. Building on these empirical results, the purpose of this work was to explore a metric to quantify breast density using our ultrasound tomography sound speed images in a manner analogous to computer-assisted mammogram segmentation for breast density analysis. Therefore, volumetric ultrasound percent density (USPD) is determined by segmenting high sound speed areas from each tomogram using a k-means clustering routine, integrating these results over the entire volume of the breast, and dividing by whole-breast volume. First, a breast phantom comprised of fat inclusions embedded in fibroglandular tissue was scanned four times with both our ultrasound tomography clinical prototype (with 4 mm spatial resolution) and CT. The coronal transmission tomograms and CT images were analyzed using semiautomatic segmentation routines, and the integrated areas of the phantom's fat inclusions were compared between the four repeated scans. The average variability for inclusion segmentation was {approx}7% and {approx}2%, respectively, and a close correlation was observed in the integrated areas between the two modalities. Next, a cohort of 93 patients was imaged, yielding volumetric coverage of the breast (45-75 sound speed tomograms/patient). The association of USPD with mammographic percent density (MPD) was evaluated using two measures: (1) qualitative, as determined by a radiologist's visual assessment using BI-RADS Criteria and (2) quantitative, via digitization and semiautomatic segmentation of craniocaudal and mediolateral oblique mammograms. A strong positive association between BI-RADS category and USPD was demonstrated [Spearman {rho}=0.69 (p<0.001)], with significant differences between all BI-RADS categories as assessed

  17. Hepatosplenic volumetric assessment at MDCT for staging liver fibrosis.

    PubMed

    Pickhardt, Perry J; Malecki, Kyle; Hunt, Oliver F; Beaumont, Claire; Kloke, John; Ziemlewicz, Timothy J; Lubner, Meghan G

    2017-07-01

    To investigate hepatosplenic volumetry at MDCT for non-invasive prediction of hepatic fibrosis. Hepatosplenic volume analysis in 624 patients (mean age, 48.8 years; 311 M/313 F) at MDCT was performed using dedicated software and compared against pathological fibrosis stage (F0 = 374; F1 = 48; F2 = 40; F3 = 65; F4 = 97). The liver segmental volume ratio (LSVR) was defined by Couinaud segments I-III over segments IV-VIII. All pre-cirrhotic fibrosis stages (METAVIR F1-F3) were based on liver biopsy within 1 year of MDCT. LSVR and total splenic volumes increased with stage of fibrosis, with mean(±SD) values of: F0: 0.26 ± 0.06 and 215.1 ± 88.5 mm(3); F1: 0.25 ± 0.08 and 294.8 ± 153.4 mm(3); F2: 0.331 ± 0.12 and 291.6 ± 197.1 mm(3); F3: 0.39 ± 0.15 and 509.6 ± 402.6 mm(3); F4: 0.56 ± 0.30 and 790.7 ± 450.3 mm(3), respectively. Total hepatic volumes showed poor discrimination (F0: 1674 ± 320 mm(3); F4: 1631 ± 691 mm(3)). For discriminating advanced fibrosis (≥F3), the ROC AUC values for LSVR, total liver volume, splenic volume and LSVR/spleen combined were 0.863, 0.506, 0.890 and 0.947, respectively. Relative changes in segmental liver volumes and total splenic volume allow for non-invasive staging of hepatic fibrosis, whereas total liver volume is a poor predictor. Unlike liver biopsy or elastography, these CT volumetric biomarkers can be obtained retrospectively on routine scans obtained for other indications. • Regional changes in hepatic volume (LSVR) correlate well with degree of fibrosis. • Total liver volume is a very poor predictor of underlying fibrosis. • Total splenic volume is associated with the degree of hepatic fibrosis. • Hepatosplenic volume assessment is comparable to elastography for staging fibrosis. • Unlike elastography, volumetric analysis can be performed retrospectively.

  18. Volumetric Spectroscopic Imaging of Glioblastoma Multiforme Radiation Treatment Volumes

    SciTech Connect

    Parra, N. Andres; Maudsley, Andrew A.; Gupta, Rakesh K.; Ishkanian, Fazilat; Huang, Kris; Walker, Gail R.; Padgett, Kyle; Roy, Bhaswati; Panoff, Joseph; Markoe, Arnold; Stoyanova, Radka

    2014-10-01

    Purpose: Magnetic resonance (MR) imaging and computed tomography (CT) are used almost exclusively in radiation therapy planning of glioblastoma multiforme (GBM), despite their well-recognized limitations. MR spectroscopic imaging (MRSI) can identify biochemical patterns associated with normal brain and tumor, predominantly by observation of choline (Cho) and N-acetylaspartate (NAA) distributions. In this study, volumetric 3-dimensional MRSI was used to map these compounds over a wide region of the brain and to evaluate metabolite-defined treatment targets (metabolic tumor volumes [MTV]). Methods and Materials: Volumetric MRSI with effective voxel size of ∼1.0 mL and standard clinical MR images were obtained from 19 GBM patients. Gross tumor volumes and edema were manually outlined, and clinical target volumes (CTVs) receiving 46 and 60 Gy were defined (CTV{sub 46} and CTV{sub 60}, respectively). MTV{sub Cho} and MTV{sub NAA} were constructed based on volumes with high Cho and low NAA relative to values estimated from normal-appearing tissue. Results: The MRSI coverage of the brain was between 70% and 76%. The MTV{sub NAA} were almost entirely contained within the edema, and the correlation between the 2 volumes was significant (r=0.68, P=.001). In contrast, a considerable fraction of MTV{sub Cho} was outside of the edema (median, 33%) and for some patients it was also outside of the CTV{sub 46} and CTV{sub 60}. These untreated volumes were greater than 10% for 7 patients (37%) in the study, and on average more than one-third (34.3%) of the MTV{sub Cho} for these patients were outside of CTV{sub 60}. Conclusions: This study demonstrates the potential usefulness of whole-brain MRSI for radiation therapy planning of GBM and revealed that areas of metabolically active tumor are not covered by standard RT volumes. The described integration of MTV into the RT system will pave the way to future clinical trials investigating outcomes in patients treated based on

  19. Widespread Volumetric Brain Changes following Tooth Loss in Female Mice.

    PubMed

    Avivi-Arber, Limor; Seltzer, Ze'ev; Friedel, Miriam; Lerch, Jason P; Moayedi, Massieh; Davis, Karen D; Sessle, Barry J

    2016-01-01

    Tooth loss is associated with altered sensory, motor, cognitive and emotional functions. These changes vary highly in the population and are accompanied by structural and functional changes in brain regions mediating these functions. It is unclear to what extent this variability in behavior and function is caused by genetic and/or environmental determinants and which brain regions undergo structural plasticity that mediates these changes. Thus, the overall goal of our research program is to identify genetic variants that control structural and functional plasticity following tooth loss. As a step toward this goal, here our aim was to determine whether structural magnetic resonance imaging (sMRI) is sensitive to detect quantifiable volumetric differences in the brains of mice of different genetic background receiving tooth extraction or sham operation. We used 67 adult female mice of 7 strains, comprising the A/J (A) and C57BL/6J (B) strains and a randomly selected sample of 5 of the 23 AXB-BXA strains (AXB1, AXB4, AXB24, BXA14, BXA24) that were produced from the A and B parental mice by recombinations and inbreeding. This panel of 25 inbred strains of genetically diverse inbred strains of mice is used for mapping chromosomal intervals throughout the genome that harbor candidate genes controlling the phenotypic variance of any trait under study. Under general anesthesia, 39 mice received extraction of 3 right maxillary molar teeth and 28 mice received sham operation. On post-extraction day 21, post-mortem whole-brain high-resolution sMRI was used to quantify the volume of 160 brain regions. Compared to sham operation, tooth extraction was associated with a significantly reduced regional and voxel-wise volumes of cortical brain regions involved in processing somatosensory, motor, cognitive and emotional functions, and increased volumes in subcortical sensorimotor and temporal limbic forebrain regions including the amygdala. Additionally, comparison of the 10 BXA14

  20. New treatment targets for axial spondyloarthritis.

    PubMed

    Sieper, Joachim

    2016-12-01

    Axial spondyloarthritis (axSpA) patients can be divided into those with structural damage in the SI joint visible on X-rays, termed radiographic axSpA or AS, and those in an earlier phase of the disease, without structural damage in the SI joint, termed non-radiographic axSpA. TNF-blockers have been shown to be highly effective in the treatment of active axSpA. Interestingly, conventional DMARDs and also non-TNF-blocker biologics targeting IL-1, IL-6 and T cells (abatacept) are not effective. Recent interest has focused on the cytokines IL-23 and IL-17 as potential treatment targets in axSpA. An open-label trial with ustekinumab showed a good efficacy in AS patients. Two placebo-controlled phase 3 trials with a mAb blocking IL-17, secukinumab, showed a good reduction in disease activity, similar to that shown for TNF blockers. Probably triggered by inflammation, new bone formation is another hallmark in AS and a potentially important treatment target. However, a previously reported inhibitory effect of NSAID treatment could not be confirmed in a recent NSAID trial.

  1. Axial compressor middle stage secondary flow study

    NASA Technical Reports Server (NTRS)

    Wagner, J. H.; Dring, R. P.; Joslyn, H. D.

    1983-01-01

    This report describes an experimental investigation of the secondary flow within and aft of an axial compressor model with thick endwall boundary layers. The objective of the study was to obtain detailed aerodynamic and trace gas concentration traverse data aft of a well documented isolated rotor for the ultimate purpose of improving the design phases of compressor development based on an improved physical understanding of secondary flow. It was determined from the flow visualization, aerodynamic, and trace gas concentration results that the relative unloading of the midspan region of the airfoil inhibitied a fullspan separation at high loading preventing the massive radial displacement of the hub corner stall to the tip. Radial distribution of high and low total pressure fluid influenced the magnitude of the spanwise distribution of loss, such that, there was a general decreases in loss near the hub to the extent that for the least loaded case a negative loss (increase in total pressure) was observed. The ability to determine the spanwise distribution of blockage was demonstrated. Large blockage was present in the endwall regions due to the corner stall and tip leakage with little blockage in the core flow region. Hub blockage was found to increase rapidly with loading.

  2. Vertebrate Axial Patterning: From Egg to Asymmetry.

    PubMed

    Houston, Douglas W

    2017-01-01

    The emergence of the bilateral embryonic body axis from a symmetrical egg has been a long-standing question in developmental biology. Historical and modern experiments point to an initial symmetry-breaking event leading to localized Wnt and Nodal growth factor signaling and subsequent induction and formation of a self-regulating dorsal "organizer." This organizer forms at the site of notochord cell internalization and expresses primarily Bone Morphogenetic Protein (BMP) growth factor antagonists that establish a spatiotemporal gradient of BMP signaling across the embryo, directing initial cell differentiation and morphogenesis. Although the basics of this model have been known for some time, many of the molecular and cellular details have only recently been elucidated and the extent that these events remain conserved throughout vertebrate evolution remains unclear. This chapter summarizes historical perspectives as well as recent molecular and genetic advances regarding: (1) the mechanisms that regulate symmetry-breaking in the vertebrate egg and early embryo, (2) the pathways that are activated by these events, in particular the Wnt pathway, and the role of these pathways in the formation and function of the organizer, and (3) how these pathways also mediate anteroposterior patterning and axial morphogenesis. Emphasis is placed on comparative aspects of the egg-to-embryo transition across vertebrates and their evolution. The future prospects for work regarding self-organization and gene regulatory networks in the context of early axis formation are also discussed.

  3. Axial residual stresses in boron fibers

    NASA Technical Reports Server (NTRS)

    Behrendt, D. R.

    1978-01-01

    The axial residual stress distribution as a function of radius was determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diameter fibers were similar, being compressive at the surface and changing monotonically to a region of tensile within the boron. At approximately 25 percent of the original radius, the stress reaches a maximum tensile stress of about 860 mn/sq.m and then decreases to a compressive stress near the tungsten boride core. Data were presented for 203 micron diameter B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102 micron diameter B/W and boron on carbon (b/C) shows that the residual stresses were similar in the outer regions of the fibers, but that large differences near and in the core were observed. The effects of these residual stresses on the fracture of boron fibers were discussed.

  4. Small axial turbine stator technology program

    NASA Technical Reports Server (NTRS)

    Brockett, W.; Kozak, A.

    1982-01-01

    An experimental investigation was conducted to determine the effects of surface finish, fillet radius, inlet boundary layer thickness, and free-stream inlet turbulence level on the aerodynamic performance of a small axial flow turbine stator. The principal objective of this program was to help understand why large turbine efficiency is not maintained when a large turbine is scaled to a smaller size. The stator used in this program as a one-sixth scale of a 762 mm (30 in.) diameter stator design with 50 vanes having a vane height of 17 mm (0.666 in.) and an aspect ratio of 1.77. A comprehensive overall test matrix was used to provide a complete engineering understanding of the effects of each variable over the full range of all the other variables. The range of each variable investigated was as follows: surface finish 0.1 micro (4 micro in.) to 2.4 micro (95 micro in.); boundary layer thickness 2 to 25 percent of channel height at each wall; fillet radius 0 mm (0 in.) to 1.0 mm (.040 in.) and turbulence 2 to 12 percent.

  5. Vector and Axial Vector Pion Form Factors

    NASA Astrophysics Data System (ADS)

    Vitz, Michael; PEN Collaboration

    2015-04-01

    Radiative pion decay π+ -->e+ νγ (RPD) provides critical input to chiral perturbation theory (χPT). Aside from the uninteresting ``inner bremsstrahlung'' contribution from QED, the RPD rate contains ``structure dependent'' terms given by FV and FA, the vector and axial-vector pion form factors, respectively. The two appear in the decay rate in combinations FV -FA and FV +FA , i.e., in the so-called SD- and SD+ terms, respectively. The latter has been measured to high precision by the PIBETA collaboration. We report on the analysis of new data, measured by the PEN collaboration in runs between 2008 and 2010 at the Paul Scherrer Institute, Switzerland. We particularly focus on the possibility of improvement in the determination of the SD- term. Precise determinations of FV and FA test the validity of the CVC hypothesis, provide numerical input for the l9 +l10 terms in the χPT lagrangian, and constrain potential non-(V - A) terms, such as a possible tensor term FT. NSF grants PHY-0970013, 1307328, and others.

  6. Small axial compressor technology, volume 1

    NASA Technical Reports Server (NTRS)

    Holman, F. F.; Kidwell, J. R.; Ware, T. C.

    1976-01-01

    A scaled single-stage, highly-loaded, axial-flow transonic compressor was tested at speeds from 70 to 110% design equivalent speed to evaluate the effects of scaling compromises and the individual and combined effects of rotor tip running clearance and rotor shroud casing treatment on the overall and blade element performance. At design speed and 1% tip clearance the stage demonstrated an efficiency of 83.2% at 96.4% design flow and a pressure ratio of 1.865. Casing treatment increased design speed surge margin 2.0 points to 12.8%. Overall performance was essentially unchanged. An increase in rotor running clearance to 2.2%, with smooth casing, reduced design speed peak efficiency 5.7 points, flow by 7.4%, pressure ratio to 1.740, and surge margin to 5.4%. Reinstalling casing treatment regained 3.5 points in design speed peak efficiency, 4.7% flow, increased pressure ratio to 1.800 and surge margin to 8.7%.

  7. Nitinol stent design - understanding axial buckling.

    PubMed

    McGrath, D J; O'Brien, B; Bruzzi, M; McHugh, P E

    2014-12-01

    Nitinol׳s superelastic properties permit self-expanding stents to be crimped without plastic deformation, but its nonlinear properties can contribute towards stent buckling. This study investigates the axial buckling of a prototype tracheobronchial nitinol stent design during crimping, with the objective of eliminating buckling from the design. To capture the stent buckling mechanism a computational model of a radial force test is simulated, where small geometric defects are introduced to remove symmetry and allow buckling to occur. With the buckling mechanism ascertained, a sensitivity study is carried out to examine the effect that the transitional plateau region of the nitinol loading curve has on stent stability. Results of this analysis are then used to redesign the stent and remove buckling. It is found that the transitional plateau region can have a significant effect on the stability of a stent during crimping, and by reducing the amount of transitional material within the stent hinges during loading the stability of a nitinol stent can be increased.

  8. Recent advances in transonic axial compressor aerodynamics

    NASA Astrophysics Data System (ADS)

    Biollo, Roberto; Benini, Ernesto

    2013-01-01

    Transonic axial flow compressors are fundamental components in aircraft engines as they make it possible to maximize pressure ratios per stage unit. This is achieved through a careful combination of both tangential flow deflections and, above all, by taking advantage of shock wave formation around the rotor blades. The resulting flow field is really complex as it features highly three-dimensional inviscid/viscous structures, strong shock-boundary layer interaction and intense tip clearance effects which negatively influence compressor efficiency. Complications are augmented at part load operation, where stall-related phenomena occur. Therefore, considerable research efforts are being spent, both numerically and experimentally, to improve efficiency and stall margin at peak efficiency and near stall operation. The present work aims at giving a complete review of the most recent advances in the field of aerodynamic design and operation of such machines. A great emphasis has been given to highlight the most relevant contribution in this field and to suggest the prospects for future developments.

  9. High Power Co-Axial SRF Coupler

    SciTech Connect

    M.L. Neubauer, R.A. Rimmer

    2009-05-01

    There are over 35 coupler designs for SRF cavities ranging in frequency from 325 to 1500 MHz. Two-thirds of these designs are coaxial couplers using disk or cylindrical ceramics in various combinations and configurations. While it is well known that dielectric losses go down by several orders of magnitude at cryogenic temperatures, it not well known that the thermal conductivity also goes down, and it is the ratio of thermal conductivity to loss tangent (SRF ceramic Quality Factor) and ceramic volume which will determine the heat load of any given design. We describe a novel robust co-axial SRF coupler design which uses compressed window technology. This technology will allow the use of highly thermally conductive materials for cryogenic windows. The mechanical designs will fit into standard-sized ConFlat® flanges for ease of assembly. Two windows will be used in a coaxial line. The distance between the windows is adjusted to cancel their reflections so that the same window can be used in many different applications at various frequencies.

  10. Giant cell tumors of the axial skeleton.

    PubMed

    Balke, Maurice; Henrichs, Marcel P; Gosheger, Georg; Ahrens, Helmut; Streitbuerger, Arne; Koehler, Michael; Bullmann, Viola; Hardes, Jendrik

    2012-01-01

    Background. We report on 19 cases of giant cell tumor of bone (GCT) affecting the spine or sacrum and evaluate the outcome of different treatment modalities. Methods. Nineteen patients with GCT of the spine (n = 6) or sacrum (n = 13) have been included in this study. The mean followup was 51.6 months. Ten sacral GCT were treated by intralesional procedures of which 4 also received embolization, and 3 with irradiation only. All spinal GCT were surgically treated. Results. Two (15.4%) patients with sacral and 4 (66.7%) with spinal tumors had a local recurrence, two of the letter developed pulmonary metastases. One local recurrence of the spine was successfully treated by serial arterial embolization, a procedure previously described only for sacral tumors. At last followup, 9 patients had no evidence of disease, 8 had stable disease, 1 had progressive disease, 1 died due to disease. Six patients had neurological deficits. Conclusions. GCT of the axial skeleton have a high local recurrence rate. Neurological deficits are common. En-bloc spondylectomy combined with embolization is the treatment of choice. In case of inoperability, serial arterial embolization seems to be an alternative not only for sacral but also for spinal tumors.

  11. Giant Cell Tumors of the Axial Skeleton

    PubMed Central

    Balke, Maurice; Henrichs, Marcel P.; Gosheger, Georg; Ahrens, Helmut; Streitbuerger, Arne; Koehler, Michael; Bullmann, Viola; Hardes, Jendrik

    2012-01-01

    Background. We report on 19 cases of giant cell tumor of bone (GCT) affecting the spine or sacrum and evaluate the outcome of different treatment modalities. Methods. Nineteen patients with GCT of the spine (n = 6) or sacrum (n = 13) have been included in this study. The mean followup was 51.6 months. Ten sacral GCT were treated by intralesional procedures of which 4 also received embolization, and 3 with irradiation only. All spinal GCT were surgically treated. Results. Two (15.4%) patients with sacral and 4 (66.7%) with spinal tumors had a local recurrence, two of the letter developed pulmonary metastases. One local recurrence of the spine was successfully treated by serial arterial embolization, a procedure previously described only for sacral tumors. At last followup, 9 patients had no evidence of disease, 8 had stable disease, 1 had progressive disease, 1 died due to disease. Six patients had neurological deficits. Conclusions. GCT of the axial skeleton have a high local recurrence rate. Neurological deficits are common. En-bloc spondylectomy combined with embolization is the treatment of choice. In case of inoperability, serial arterial embolization seems to be an alternative not only for sacral but also for spinal tumors. PMID:22448122

  12. Is there a role for the use of volumetric cone beam computed tomography in periodontics?

    PubMed

    du Bois, A H; Kardachi, B; Bartold, P M

    2012-03-01

    Volumetric computed cone beam tomography offers a number of significant advantages over conventional intraoral and extraoral panoramic radiography, as well as computed tomography. To date, periodontal diagnosis has relied heavily on the assessment of both intraoral radiographs and extraoral panoramic radiographs. With emerging technology in radiology there has been considerable interest in the role that volumetric cone beam computed tomography might play in periodontal diagnostics. This narrative reviews the current evidence and considers whether there is a role for volumetric cone beam computed tomography in periodontics.

  13. In vivo volumetric imaging of biological dynamics in deep tissue via wavefront engineering

    PubMed Central

    Kong, Lingjie; Tang, Jianyong; Cui, Meng

    2016-01-01

    Biological systems undergo dynamical changes continuously which span multiple spatial and temporal scales. To study these complex biological dynamics in vivo, high-speed volumetric imaging that can work at large imaging depth is highly desired. However, deep tissue imaging suffers from wavefront distortion, resulting in reduced Strehl ratio and image quality. Here we combine the two wavefront engineering methods developed in our lab, namely the optical phase-locked ultrasound lens based volumetric imaging and the iterative multiphoton adaptive compensation technique, and demonstrate in vivo volumetric imaging of microglial and mitochondrial dynamics at large depth in mouse brain cortex and lymph node, respectively. PMID:26832504

  14. In vivo volumetric imaging of biological dynamics in deep tissue via wavefront engineering.

    PubMed

    Kong, Lingjie; Tang, Jianyong; Cui, Meng

    2016-01-25

    Biological systems undergo dynamical changes continuously which span multiple spatial and temporal scales. To study these complex biological dynamics in vivo, high-speed volumetric imaging that can work at large imaging depth is highly desired. However, deep tissue imaging suffers from wavefront distortion, resulting in reduced Strehl ratio and image quality. Here we combine the two wavefront engineering methods developed in our lab, namely the optical phase-locked ultrasound lens based volumetric imaging and the iterative multiphoton adaptive compensation technique, and demonstrate in vivo volumetric imaging of microglial and mitochondrial dynamics at large depth in mouse brain cortex and lymph node, respectively.

  15. Three-dimensional reconstruction and measurements of zebrafish larvae from high-throughput axial-view in vivo imaging

    PubMed Central

    Guo, Yuanhao; Veneman, Wouter J.; Spaink, Herman P.; Verbeek, Fons J.

    2017-01-01

    High-throughput imaging is applied to provide observations for accurate statements on phenomena in biology and this has been successfully applied in the domain of cells, i.e. cytomics. In the domain of whole organisms, we need to take the hurdles to ensure that the imaging can be accomplished with a sufficient throughput and reproducibility. For vertebrate biology, zebrafish is a popular model system for High-throughput applications. The development of the Vertebrate Automated Screening Technology (VAST BioImager), a microscope mounted system, enables the application of zebrafish high-throughput screening. The VAST BioImager contains a capillary that holds a zebrafish for imaging. Through the rotation of the capillary, multiple axial-views of a specimen can be acquired. For the VAST BioImager, fluorescence and/or confocal microscopes are used. Quantitation of a specific signal as derived from a label in one fluorescent channel requires insight in the zebrafish volume to be able to normalize quantitation to volume units. However, from the setup of the VAST BioImager, a specimen volume cannot be straightforwardly derived. We present a high-throughput axial-view imaging architecture based on the VAST BioImager. We propose profile-based 3D reconstruction to produce 3D volumetric representations for zebrafish larvae using the axial-views. Volume and surface area can then be derived from the 3D reconstruction to obtain the shape characteristics in high-throughput measurements. In addition, we develop a calibration and a validation of our methodology. From our measurements we show that with a limited amount of views, accurate measurements of volume and surface area for zebrafish larvae can be obtained. We have applied the proposed method on a range of developmental stages in zebrafish and produced metrical references for the volume and surface area for each stage. PMID:28663894

  16. Phase-transfer-catalyzed asymmetric synthesis of axially chiral anilides.

    PubMed

    Liu, Kun; Wu, Xiangfei; Kan, S B Jennifer; Shirakawa, Seiji; Maruoka, Keiji

    2013-12-01

    Catalytic asymmetric synthesis of axially chiral o-iodoanilides and o-tert-butylanilides as useful chiral building blocks was achieved by means of binaphthyl-modified chiral quaternary ammonium-salt-catalyzed N-alkylations under phase-transfer conditions. The synthetic utility of axially chiral products was demonstrated in various transformations. For example, axially chiral N-allyl-o-iodoanilide was transformed to 3-methylindoline by means of radical cyclization with high chirality transfer from axial chirality to C-centered chirality. Furthermore, stereochemical information on axial chirality in o-tert-butylanilides could be used as a template to control the stereochemistry of subsequent transformations. The transition-state structure of the present phase-transfer reaction was discussed on the basis of the X-ray crystal structure of ammonium anilide, which was prepared from binaphthyl-modified chiral ammonium bromide and o-iodoanilide. The chiral tetraalkylammonium bromide as a phase-transfer catalyst recognized the steric difference between the ortho substituents on anilide to obtain high enantioselectivity. The size and structural effects of the ortho substituents on anilide were investigated, and a wide variety of axially chiral anilides that possess various functional groups could be synthesized with high enantioselectivities. This method is the only general way to access a variety of axially chiral anilides in a highly enantioselective fashion reported to date. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Axial elongation following prolonged near work in myopes and emmetropes.

    PubMed

    Woodman, Emily C; Read, Scott A; Collins, Michael J; Hegarty, Katherine J; Priddle, Scott B; Smith, Josephine M; Perro, Judd V

    2011-05-01

    To investigate the influence of a period of sustained near work upon axial length in groups of emmetropes (EMM) and myopes. Forty young adult subjects (20 myopes and 20 emmetropes) were recruited for the study. Myopes were further classified as early onset (EOM), late onset (LOM), stable (SM) or progressing (PM) subgroups. Axial length was measured with the IOLMaster instrument before, immediately after and then again 10 min after a continuous 30 min near task of 5 D accommodation demand. Measures of distance objective refraction were also collected. Significant changes in axial length were observed immediately following the near task. EOM axial length elongated on average by 0.027±0.021 mm, LOM by 0.014±0.020 mm, EMM by 0.010±0.015 mm, PM by 0.031±0.022 mm and SM by 0.014±0.018 mm. At the conclusion of the 10 min regression period, axial length measures were not significantly different from baseline values. Axial elongation was observed following a prolonged near task. Both EOM and PM groups showed increases in axial length that were significantly greater than emmetropes.

  18. Automatic coregistration of volumetric images based on implanted fiducial markers.

    PubMed

    Koch, Martin; Maltz, Jonathan S; Belongie, Serge J; Gangadharan, Bijumon; Bose, Supratik; Shukla, Himanshu; Bani-Hashemi, Ali R

    2008-10-01

    The accurate delivery of external beam radiation therapy is often facilitated through the implantation of radio-opaque fiducial markers (gold seeds). Before the delivery of each treatment fraction, seed positions can be determined via low dose volumetric imaging. By registering these seed locations with the corresponding locations in the previously acquired treatment planning computed tomographic (CT) scan, it is possible to adjust the patient position so that seed displacement is accommodated. The authors present an unsupervised automatic algorithm that identifies seeds in both planning and pretreatment images and subsequently determines a rigid geometric transformation between the two sets. The algorithm is applied to the imaging series of ten prostate cancer patients. Each test series is comprised of a single multislice planning CT and multiple megavoltage conebeam (MVCB) images. Each MVCB dataset is obtained immediately prior to a subsequent treatment session. Seed locations were determined to within 1 mm with an accuracy of 97 +/- 6.1% for datasets obtained by application of a mean imaging dose of 3.5 cGy per study. False positives occurred in three separate instances, but only when datasets were obtained at imaging doses too low to enable fiducial resolution by a human operator, or when the prostate gland had undergone large displacement or significant deformation. The registration procedure requires under nine seconds of computation time on a typical contemporary computer workstation.

  19. 3D volumetric radar using 94-GHz millimeter waves

    NASA Astrophysics Data System (ADS)

    Takács, Barnabás

    2006-05-01

    This article describes a novel approach to the real-time visualization of 3D imagery obtained from a 3D millimeter wave scanning radar. The MMW radar system employs a spinning antenna to generate a fan-shaped scanning pattern of the entire scene. The beams formed this way provide all weather 3D distance measurements (range/azimuth display) of objects as they appear on the ground. The beam width of the antenna and its side lobes are optimized to produce the best possible resolution even at distances of up to 15 Kms. To create a full 3D data set the fan-pattern is tilted up and down with the help of a controlled stepper motor. For our experiments we collected data at 0.1 degrees increments while using both bi-static as well as a mono-static antennas in our arrangement. The data collected formed a stack of range-azimuth images in the shape of a cone. This information is displayed using our high-end 3D visualization engine capable of displaying high-resolution volumetric models with 30 frames per second. The resulting 3D scenes can then be viewed from any angle and subsequently processed to integrate, fuse or match them against real-life sensor imagery or 3D model data stored in a synthetic database.

  20. Volumetric microscale particle tracking velocimetry (PTV) in porous media

    NASA Astrophysics Data System (ADS)

    Guo, Tianqi; Aramideh, Soroush; Ardekani, Arezoo M.; Vlachos, Pavlos P.

    2016-11-01

    The steady-state flow through refractive-index-matched glass bead microchannels is measured using microscopic particle tracking velocimetry (μPTV). A novel technique is developed to volumetrically reconstruct particles from oversampled two-dimensional microscopic images of fluorescent particles. Fast oversampling of the quasi-steady-state flow field in the lateral direction is realized by a nano-positioning piezo stage synchronized with a fast CMOS camera. Experiments at different Reynolds numbers are carried out for flows through a series of both monodispersed and bidispersed glass bead microchannels with various porosities. The obtained velocity fields at pore-scale (on the order of 10 μm) are compared with direct numerical simulations (DNS) conducted in the exact same geometries reconstructed from micro-CT scans of the glass bead microchannels. The developed experimental method would serve as a new approach for exploring the flow physics at pore-scale in porous media, and also provide benchmark measurements for validation of numerical simulations.

  1. Intuitive Exploration of Volumetric Data Using Dynamic Galleries.

    PubMed

    Jönsson, Daniel; Falk, Martin; Ynnerman, Anders

    2016-01-01

    In this work we present a volume exploration method designed to be used by novice users and visitors to science centers and museums. The volumetric digitalization of artifacts in museums is of rapidly increasing interest as enhanced user experience through interactive data visualization can be achieved. This is, however, a challenging task since the vast majority of visitors are not familiar with the concepts commonly used in data exploration, such as mapping of visual properties from values in the data domain using transfer functions. Interacting in the data domain is an effective way to filter away undesired information but it is difficult to predict where the values lie in the spatial domain. In this work we make extensive use of dynamic previews instantly generated as the user explores the data domain. The previews allow the user to predict what effect changes in the data domain will have on the rendered image without being aware that visual parameters are set in the data domain. Each preview represents a subrange of the data domain where overview and details are given on demand through zooming and panning. The method has been designed with touch interfaces as the target platform for interaction. We provide a qualitative evaluation performed with visitors to a science center to show the utility of the approach.

  2. Optical artefact characterization and correction in volumetric scintillation dosimetry

    PubMed Central

    Robertson, Daniel; Hui, Cheukkai; Archambault, Louis; Mohan, Radhe; Beddar, Sam

    2014-01-01

    The goals of this study were (1) to characterize the optical artefacts affecting measurement accuracy in a volumetric liquid scintillation detector, and (2) to develop methods to correct for these artefacts. The optical artefacts addressed were photon scattering, refraction, camera perspective, vignetting, lens distortion, the lens point spread function, stray radiation, and noise in the camera. These artefacts were evaluated by theoretical and experimental means, and specific correction strategies were developed for each artefact. The effectiveness of the correction methods was evaluated by comparing raw and corrected images of the scintillation light from proton pencil beams against validated Monte Carlo calculations. Blurring due to the lens and refraction at the scintillator tank-air interface were found to have the largest effect on the measured light distribution, and lens aberrations and vignetting were important primarily at the image edges. Photon scatter in the scintillator was not found to be a significant source of artefacts. The correction methods effectively mitigated the artefacts, increasing the average gamma analysis pass rate from 66% to 98% for gamma criteria of 2% dose difference and 2 mm distance to agreement. We conclude that optical artefacts cause clinically meaningful errors in the measured light distribution, and we have demonstrated effective strategies for correcting these optical artefacts. PMID:24321820

  3. Optical artefact characterization and correction in volumetric scintillation dosimetry

    NASA Astrophysics Data System (ADS)

    Robertson, Daniel; Hui, Cheukkai; Archambault, Louis; Mohan, Radhe; Beddar, Sam

    2014-01-01

    The goals of this study were (1) to characterize the optical artefacts affecting measurement accuracy in a volumetric liquid scintillator detector, and (2) to develop methods to correct for these artefacts. The optical artefacts addressed were photon scattering, refraction, camera perspective, vignetting, lens distortion, the lens point spread function, stray radiation, and noise in the camera. These artefacts were evaluated by theoretical and experimental means, and specific correction strategies were developed for each artefact. The effectiveness of the correction methods was evaluated by comparing raw and corrected images of the scintillation light from proton pencil beams against validated Monte Carlo calculations. Blurring due to the lens and refraction at the scintillator tank-air interface were found to have the largest effect on the measured light distribution, and lens aberrations and vignetting were important primarily at the image edges. Photon scatter in the scintillator was not found to be a significant source of artefacts. The correction methods effectively mitigated the artefacts, increasing the average gamma analysis pass rate from 66% to 98% for gamma criteria of 2% dose difference and 2 mm distance to agreement. We conclude that optical artefacts cause clinically meaningful errors in the measured light distribution, and we have demonstrated effective strategies for correcting these optical artefacts.

  4. Laser beam steering via wave mixing in volumetric thermal gratings

    NASA Astrophysics Data System (ADS)

    Tyler, David W.

    1992-06-01

    A volumetric thermal grating (VTG) is a spatially periodic refractive index variation in a volume of gas or liquid, generated by imaging interference fringes into the medium. The fringes can be created and varied by steering laser write beams electronically with acousto- optic (A-O) cells. While the wavelength of the write beams is chosen to be absorbed by a dopant in the VTG medium, a read beam at an off-resonance wavelength can be manipulated by diffraction from the resulting index grating. Potential applications include resonator and amplifier optical isolation prepulse suppression in high-gain amplifiers, noninertial steering of large-diameter laser beams, transfer of phase information between beams to facilitate adaptive optics, Q-switching of chemical lasers, and line selection in broadband lasers. In this paper, we present a preliminary assessment of VTG utility for these optical systems applications by quantitative analysis of the medium density dynamics. In Section 2, we derive a relation between A-O acoustic frequency uncertainty and VTG pointing/steering uncertainty, which also scales desired steering range to required A-O frequency modulation bandwidth. In Section 3, we discuss the temporal response of a doped rare-gas VTG medium. Section 4 is an assessment of VTG beam-steering performance potential using available technology.

  5. Volumetric PIV in Patient-Specific Cerebral Aneurysm

    NASA Astrophysics Data System (ADS)

    Brindise, Melissa; Dickerhoff, Ben; Saloner, David; Rayz, Vitaliy; Vlachos, Pavlos

    2016-11-01

    Cerebral aneurysms impose a unique challenge in which neurosurgeons must assess and decide between the risk of rupture and risk of treatment for each patient. Risk of rupture is often difficult to determine and most commonly assessed using geometric data including the size and shape of the aneurysm and parent vessel. Hemodynamics is thought to play a major role in the growth and rupture of a cerebral aneurysm, but its specific influence is largely unknown due to the inability of in vivo modalities to characterize detailed flow fields and limited in vitro studies. In this work, we use a patient-specific basilar tip aneurysm model and volumetric particle image velocimetry (PIV). In vivo, 4-D PC-MRI measurements were obtained for this aneurysm and the extracted pulsatile waveform was used for the in vitro study. Clinically relevant metrics including wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT), 3-D pressure contours, and pressure wave speed were subsequently computed. This is the first study to investigate in vitro 3-D pressure fields within a cerebral aneurysm. The results of this study demonstrate how these metrics influence the biomechanics of the aneurysm and ultimately their affect on the risk of rupture.

  6. Cortical thickness and brain volumetric analysis in body dysmorphic disorder

    PubMed Central

    Madsen, Sarah K.; Zai, Alex; Pirnia, Tara; Arienzo, Donatello; Zhan, Liang; Moody, Teena D.; Thompson, Paul M.; Feusner, Jamie D.

    2015-01-01

    Individuals with body dysmorphic disorder (BDD) suffer from preoccupations with perceived defects in physical appearance, causing severe distress and disability. Although BDD affects 1-2% of the population, the neurobiology is not understood. Discrepant results in previous volumetric studies may be due to small sample sizes, and no study has investigated cortical thickness in BDD. The current study is the largest neuroimaging analysis of BDD. Participants included 49 medication-free, right-handed individuals with DSM-IV BDD and 44 healthy controls matched by age, sex, and education. Using high-resolution T1-weighted magnetic resonance imaging, we computed vertex-wise gray matter (GM) thickness on the cortical surface and GM volume using voxel-based morphometry. We also computed volumes in cortical and subcortical regions of interest. In addition to group comparisons, we investigated associations with symptom severity, insight, and anxiety within the BDD group. In BDD, greater anxiety was significantly associated with thinner GM in the left superior temporal cortex and greater GM volume in the right caudate nucleus. There were no significant differences in cortical thickness, GM volume, or volumes in regions of interest between BDD and control subjects. Subtle associations with clinical symptoms may characterize brain morphometric patterns in BDD, rather than large group differences in brain structure. PMID:25797401

  7. A volumetric flow sensor for automotive injection systems

    NASA Astrophysics Data System (ADS)

    Schmid, U.; Krötz, G.; Schmitt-Landsiedel, D.

    2008-04-01

    For further optimization of the automotive power train of diesel engines, advanced combustion processes require a highly flexible injection system, provided e.g. by the common rail (CR) injection technique. In the past, the feasibility to implement injection nozzle volumetric flow sensors based on the thermo-resistive measurement principle has been demonstrated up to injection pressures of 135 MPa (1350 bar). To evaluate the transient behaviour of the system-integrated flow sensors as well as an injection amount indicator used as a reference method, hydraulic simulations on the system level are performed for a CR injection system. Experimentally determined injection timings were found to be in good agreement with calculated values, especially for the novel sensing element which is directly implemented into the hydraulic system. For the first time pressure oscillations occurring after termination of the injection pulse, predicted theoretically, could be verified directly in the nozzle. In addition, the injected amount of fuel is monitored with the highest resolution ever reported in the literature.

  8. Volumetric Security Alarm Based on a Spherical Ultrasonic Transducer Array

    NASA Astrophysics Data System (ADS)

    Sayin, Umut; Scaini, Davide; Arteaga, Daniel

    Most of the existent alarm systems depend on physical or visual contact. The detection area is often limited depending on the type of the transducer, creating blind spots. Our proposition is a truly volumetric alarm system that can detect any movement in the intrusion area, based on monitoring the change over time of the impulse response of the room, which acts as an acoustic footprint. The device depends on an omnidirectional ultrasonic transducer array emitting sweep signals to calculate the impulse response in short intervals. Any change in the room conditions is monitored through a correlation function. The sensitivity of the alarm to different objects and different environments depends on the sweep duration, sweep bandwidth, and sweep interval. Successful detection of intrusions also depends on the size of the monitoring area and requires an adjustment of emitted ultrasound power. Strong air flow affects the performance of the alarm. A method for separating moving objects from strong air flow is devised using an adaptive thresholding on the correlation function involving a series of impulse response measurements. The alarm system can be also used for fire detection since air flow sourced from heating objects differ from random nature of the present air flow. Several measurements are made to test the integrity of the alarm in rooms sizing from 834-2080m3 with irregular geometries and various objects. The proposed system can efficiently detect intrusion whilst adequate emitting power is provided.

  9. Volumetric Measurements of Amnioserosa Cells in Developing Drosophila

    NASA Astrophysics Data System (ADS)

    Mashburn, David; Jayasinghe, Aroshan; Hutson, Shane

    2013-03-01

    The behavior of cells in tissue in developing Drosophila melanogaster has become increasingly clearer over the past few decades, in large part due to advances in imaging techniques, genetic markers, predictive modeling, and micromanipulation (notably laser microsurgery). We now know apical contractions in amnioserosa cells are a significant factor in large scale processes like germ band retraction and dorsal closure. Also, laser microsurgery induces cellular recoil that strongly mimics a 2D elastic sheet. Still, what we know about these processes comes entirely from the apical surface where the standard fluorescent markers like cadherin are located, but many open questions exist concerning the remaining ``dark'' portion of cells. Does cell volume remain constant during contraction or do cells leak? Also, what shape changes do cells undergo? Do they bulge, wedge, contract prismatically, or something else? By using a marker that labels the entire membrane of amnioserosa cells (Resille, 117) and adapting our watershed segmentation routines for 4D datasets, we have been able to quantify the entire volumetric region of cells in tissue through time and compare changes in apical area and volume. Preliminary results suggest a fairly constant volume over the course of a contraction cycle.

  10. Skeletal muscle tissue engineering: strategies for volumetric constructs.

    PubMed

    Cittadella Vigodarzere, Giorgio; Mantero, Sara

    2014-01-01

    Skeletal muscle tissue is characterized by high metabolic requirements, defined structure and high regenerative potential. As such, it constitutes an appealing platform for tissue engineering to address volumetric defects, as proven by recent works in this field. Several issues common to all engineered constructs constrain the variety of tissues that can be realized in vitro, principal among them the lack of a vascular system and the absence of reliable cell sources; as it is, the only successful tissue engineering constructs are not characterized by active function, present limited cellular survival at implantation and possess low metabolic requirements. Recently, functionally competent constructs have been engineered, with vascular structures supporting their metabolic requirements. In addition to the use of biochemical cues, physical means, mechanical stimulation and the application of electric tension have proven effective in stimulating the differentiation of cells and the maturation of the constructs; while the use of co-cultures provided fine control of cellular developments through paracrine activity. This review will provide a brief analysis of some of the most promising improvements in the field, with particular attention to the techniques that could prove easily transferable to other branches of tissue engineering.

  11. Ice volumetric changes on active volcanoes in southern Chile

    NASA Astrophysics Data System (ADS)

    Rivera, Andrés; Bown, Francisca; Mella, Ronald; Wendt, Jens; Casassa, Gino; Acuña, César; Rignot, Eric; Clavero, Jorge; Brock, Benjamin

    Most of the glaciers in southern Chile have been retreating and shrinking during recent decades in response to atmospheric warming and decrease in precipitation. However, some glacier fluctuations are directly associated with the effusive and geothermal activity of ice-covered active volcanoes widely distributed in the region. The aim of this paper is to study the ice volumetric changes by comparing several topographic datasets. A maximum mean ice thinning rate of 0.81 ± 0.45 m a-1 was observed on the ash/debris-covered ablation area of Volcán Villarrica between 1961 and 2004, whilst on Volcán Mocho the signal-to-noise ratio was too small to yield any conclusion. An area reduction of 0.036 ± 0.019 km2 a-1 since 1976 was obtained on Glaciar Mocho, while on Volcán Villarrica the area change was -0.090 ± 0.034 km2 a-1 between 1976 and 2005. Glaciers on active volcanoes are therefore shrinking, mainly in response to climatic driving factors. However, volcanic activity is affecting glaciers in two opposite ways: ash/debris advection is helping to reduce surface ablation at lower reaches by insulating the ice from solar radiation, while geothermal activity is probably enhancing melting and water production at the bedrock, resulting in negative ice-elevation changes.

  12. Quality assurance of volumetric modulated arc therapy using Elekta Synergy.

    PubMed

    Haga, Akihiro; Nakagawa, Keiichi; Shiraishi, Kenshiro; Itoh, Saori; Terahara, Atsuro; Yamashita, Hideomi; Ohtomo, Kuni; Saegusa, Shigeki; Imae, Toshikazu; Yoda, Kiyoshi; Pellegrini, Roberto

    2009-01-01

    PURPOSE. Recently, Elekta has supplied volumetric modulated arc therapy (VMAT) in which multi-leaf collimator (MLC) shape, jaw position, collimator angle, and gantry speed vary continuously during gantry rotation. A quality assurance procedure for VMAT delivery is described. METHODS AND MATERIALS. A single-arc VMAT plan with 73 control points (CPs) and 5-degree gantry angle spacing for a prostate cancer patient has been created by ERGO + + treatment planning system (TPS), where MLC shapes are given by anatomic relationship between a target and organs at risk and the monitor unit for each CP is optimized based on given dose prescriptions. Actual leaf and jaw positions, gantry angles and dose rates during prostate VMAT delivery were recorded in every 0.25 seconds, and the errors between planned and actual values were evaluated. The dose re-calculation using these recorded data has been performed and compared with the original TPS plan using the gamma index. RESULTS. Typical peak errors of gantry angles, leaf positions, and jaw positions were 3 degrees, 0.6 mm, and 1 mm, respectively. The dose distribution obtained by the TPS plan and the recalculated one agreed well under 2%-2 mm gamma index criteria. CONCLUSIONS. Quality assurance for prostate VMAT delivery has been performed with a satisfied result.

  13. Normative biometrics for fetal ocular growth using volumetric MRI reconstruction.

    PubMed

    Velasco-Annis, Clemente; Gholipour, Ali; Afacan, Onur; Prabhu, Sanjay P; Estroff, Judy A; Warfield, Simon K

    2015-04-01

    To determine normative ranges for fetal ocular biometrics between 19 and 38 weeks gestational age (GA) using volumetric MRI reconstruction. The 3D images of 114 healthy fetuses between 19 and 38 weeks GA were created using super-resolution volume reconstructions from MRI slice acquisitions. These 3D images were semi-automatically segmented to measure fetal orbit volume, binocular distance (BOD), interocular distance (IOD), and ocular diameter (OD). All biometry correlated with GA (Volume, Pearson's correlation coefficient (CC) = 0.9680; BOD, CC = 0.9552; OD, CC = 0.9445; and IOD, CC = 0.8429), and growth curves were plotted against linear and quadratic growth models. Regression analysis showed quadratic models to best fit BOD, IOD, and OD and a linear model to best fit volume. Orbital volume had the greatest correlation with GA, although BOD and OD also showed strong correlation. The normative data found in this study may be helpful for the detection of congenital fetal anomalies with more consistent measurements than are currently available. © 2015 John Wiley & Sons, Ltd. © 2015 John Wiley & Sons, Ltd.

  14. Volumetric Survey Speed: A Figure of Merit for Transient Surveys

    NASA Astrophysics Data System (ADS)

    Bellm, Eric C.

    2016-08-01

    Time-domain surveys can exchange sky coverage for revisit frequency, complicating the comparison of their relative capabilities. By using different revisit intervals, a specific camera may execute surveys optimized for discovery of different classes of transient objects. We propose a new figure of merit, the instantaneous volumetric survey speed, for evaluating transient surveys. This metric defines the trade between cadence interval and snapshot survey volume and so provides a natural means of comparing survey capability. The related metric of areal survey speed imposes a constraint on the range of possible revisit times: we show that many modern time-domain surveys are limited by the amount of fresh sky available each night. We introduce the concept of “spectroscopic accessibility” and discuss its importance for transient science goals requiring followup observing. We present an extension of the control time algorithm for cases where multiple consecutive detections are required. Finally, we explore how survey speed and choice of cadence interval determine the detection rate of transients in the peak absolute magnitude-decay timescale phase space.

  15. Volumetric stress-strain analysis of optohydrodynamically suspended biological cells.

    PubMed

    Kohles, Sean S; Liang, Yu; Saha, Asit K

    2011-01-01

    Ongoing investigations are exploring the biomechanical properties of isolated and suspended biological cells in pursuit of understanding single-cell mechanobiology. An optical tweezer with minimal applied laser power has positioned biologic cells at the geometric center of a microfluidic cross-junction, creating a novel optohydrodynamic trap. The resulting fluid flow environment facilitates unique multiaxial loading of single cells with site-specific normal and shear stresses resulting in a physical albeit extensional state. A recent two-dimensional analysis has explored the cytoskeletal strain response due to these fluid-induced stresses [Wilson and Kohles, 2010, "Two-Dimensional Modeling of Nanomechanical Stresses-Strains in Healthy and Diseased Single-Cells During Microfluidic Manipulation," J Nanotechnol Eng Med, 1(2), p. 021005]. Results described a microfluidic environment having controlled nanometer and piconewton resolution. In this present study, computational fluid dynamics combined with multiphysics modeling has further characterized the applied fluid stress environment and the solid cellular strain response in three dimensions to accompany experimental cell stimulation. A volumetric stress-strain analysis was applied to representative living cell biomechanical data. The presented normal and shear stress surface maps will guide future microfluidic experiments as well as provide a framework for characterizing cytoskeletal structure influencing the stress to strain response.

  16. Volumetric Modulated Arc Therapy (VMAT) Treatment Planning for Superficial Tumors

    SciTech Connect

    Zacarias, Albert S.; Brown, Mellonie F.; Mills, Michael D.

    2010-10-01

    The physician's planning objective is often a uniform dose distribution throughout the planning target volume (PTV), including superficial PTVs on or near the surface of a patient's body. Varian's Eclipse treatment planning system uses a progressive resolution optimizer (PRO), version 8.2.23, for RapidArc dynamic multileaf collimator volumetric modulated arc therapy planning. Because the PRO is a fast optimizer, optimization convergence errors (OCEs) produce dose nonuniformity in the superficial area of the PTV. We present a postsurgical cranial case demonstrating the recursive method our clinic uses to produce RapidArc treatment plans. The initial RapidArc treatment plan generated using one 360{sup o} arc resulted in substantial dose nonuniformity in the superficial section of the PTV. We demonstrate the use of multiple arcs to produce improved dose uniformity in this region. We also compare the results of this superficial dose compensation method to the results of a recursive method of dose correction that we developed in-house to correct optimization convergence errors in static intensity-modulated radiation therapy treatment plans. The results show that up to 4 arcs may be necessary to provide uniform dose to the surface of the PTV with the current version of the PRO.

  17. Solenoidal filtering of volumetric velocity measurements using Gaussian process regression

    NASA Astrophysics Data System (ADS)

    Azijli, Iliass; Dwight, Richard P.

    2015-11-01

    Volumetric velocity measurements of incompressible flows contain spurious divergence due to measurement noise, despite mass conservation dictating that the velocity field must be divergence-free (solenoidal). We investigate the use of Gaussian process regression to filter spurious divergence, returning analytically solenoidal velocity fields. We denote the filter solenoidal Gaussian process regression (SGPR) and formulate it within the Bayesian framework to allow a natural inclusion of measurement uncertainty. To enable efficient handling of large data sets on regular and near-regular grids, we propose a solution procedure that exploits the Toeplitz structure of the system matrix. We apply SGPR to two synthetic and two experimental test cases and compare it with two other recently proposed solenoidal filters. For the synthetic test cases, we find that SGPR consistently returns more accurate velocity, vorticity and pressure fields. From the experimental test cases, we draw two important conclusions. Firstly, it is found that including an accurate model for the local measurement uncertainty further improves the accuracy of the velocity field reconstructed with SGPR. Secondly, it is found that all solenoidal filters result in an improved reconstruction of the pressure field, as verified with microphone measurements. The results obtained with SGPR are insensitive to correlation length, demonstrating the robustness of the filter to its parameters.

  18. Illustration-inspired depth enhanced volumetric medical visualization.

    PubMed

    Svakhine, Nikolai A; Ebert, David S; Andrews, William M

    2009-01-01

    Volume illustration can be used to provide insight into source data from CT/MRI scanners in much the same way as medical illustration depicts the important details of anatomical structures. As such, proven techniques used in medical illustration should be transferable to volume illustration, providing scientists with new tools to visualize their data. In recent years, a number of techniques have been developed to enhance the rendering pipeline and create illustrative effects similar to the ones found in medical textbooks and surgery manuals. Such effects usually highlight important features of the subject while subjugating its context and providing depth cues for correct perception. Inspired by traditional visual and line-drawing techniques found in medical illustration, we have developed a collection of fast algorithms for more effective emphasis/de-emphasis of data as well as conveyance of spatial relationships. Our techniques utilize effective outlining techniques and selective depth enhancement to provide perceptual cues of object importance as well as spatial relationships in volumetric datasets. Moreover, we have used illustration principles to effectively combine and adapt basic techniques so that they work together to provide consistent visual information and a uniform style.

  19. Volumetric Stress-Strain Analysis of Optohydrodynamically Suspended Biological Cells

    PubMed Central

    Liang, Yu; Saha, Asit K.

    2011-01-01

    Ongoing investigations are exploring the biomechanical properties of isolated and suspended biological cells in pursuit of understanding single-cell mechanobiology. An optical tweezer with minimal applied laser power has positioned biologic cells at the geometric center of a microfluidic cross-junction, creating a novel optohydrodynamic trap. The resulting fluid flow environment facilitates unique multiaxial loading of single cells with site-specific normal and shear stresses resulting in a physical albeit extensional state. A recent two-dimensional analysis has explored the cytoskeletal strain response due to these fluid-induced stresses [Wilson and Kohles, 2010, “Two-Dimensional Modeling of Nanomechanical Stresses-Strains in Healthy and Diseased Single-Cells During Microfluidic Manipulation,” J Nanotechnol Eng Med, 1(2), p. 021005]. Results described a microfluidic environment having controlled nanometer and piconewton resolution. In this present study, computational fluid dynamics combined with multiphysics modeling has further characterized the applied fluid stress environment and the solid cellular strain response in three dimensions to accompany experimental cell stimulation. A volumetric stress-strain analysis was applied to representative living cell biomechanical data. The presented normal and shear stress surface maps will guide future microfluidic experiments as well as provide a framework for characterizing cytoskeletal structure influencing the stress to strain response. PMID:21186894

  20. Surface-Constrained Volumetric Brain Registration Using Harmonic Mappings

    PubMed Central

    Joshi, Anand A.; Shattuck, David W.; Thompson, Paul M.; Leahy, Richard M.

    2015-01-01

    In order to compare anatomical and functional brain imaging data across subjects, the images must first be registered to a common coordinate system in which anatomical features are aligned. Intensity-based volume registration methods can align subcortical structures well, but the variability in sulcal folding patterns typically results in misalignment of the cortical surface. Conversely, surface-based registration using sulcal features can produce excellent cortical alignment but the mapping between brains is restricted to the cortical surface. Here we describe a method for volumetric registration that also produces an accurate one-to-one point correspondence between cortical surfaces. This is achieved by first parameterizing and aligning the cortical surfaces using sulcal landmarks. We then use a constrained harmonic mapping to extend this surface correspondence to the entire cortical volume. Finally, this mapping is refined using an intensity-based warp. We demonstrate the utility of the method by applying it to T1-weighted magnetic resonance images (MRI). We evaluate the performance of our proposed method relative to existing methods that use only intensity information; for this comparison we compute the inter-subject alignment of expert-labeled sub-cortical structures after registration. PMID:18092736

  1. Volumetric Real-Time Imaging Using a CMUT Ring Array

    PubMed Central

    Choe, Jung Woo; Oralkan, Ömer; Nikoozadeh, Amin; Gencel, Mustafa; Stephens, Douglas N.; O’Donnell, Matthew; Sahn, David J.; Khuri-Yakub, Butrus T.

    2012-01-01

    A ring array provides a very suitable geometry for forward-looking volumetric intracardiac and intravascular ultrasound imaging. We fabricated an annular 64-element capacitive micromachined ultrasonic transducer (CMUT) array featuring a 10-MHz operating frequency and a 1.27-mm outer radius. A custom software suite was developed to run on a PC-based imaging system for real-time imaging using this device. This paper presents simulated and experimental imaging results for the described CMUT ring array. Three different imaging methods—flash, classic phased array (CPA), and synthetic phased array (SPA)—were used in the study. For SPA imaging, two techniques to improve the image quality—Hadamard coding and aperture weighting—were also applied. The results show that SPA with Hadamard coding and aperture weighting is a good option for ring-array imaging. Compared with CPA, it achieves better image resolution and comparable signal-to-noise ratio at a much faster image acquisition rate. Using this method, a fast frame rate of up to 463 volumes per second is achievable if limited only by the ultrasound time of flight; with the described system we reconstructed three cross-sectional images in real-time at 10 frames per second, which was limited by the computation time in synthetic beamforming. PMID:22718870

  2. Cortical thickness and brain volumetric analysis in body dysmorphic disorder.

    PubMed

    Madsen, Sarah K; Zai, Alex; Pirnia, Tara; Arienzo, Donatello; Zhan, Liang; Moody, Teena D; Thompson, Paul M; Feusner, Jamie D

    2015-04-30

    Individuals with body dysmorphic disorder (BDD) suffer from preoccupations with perceived defects in physical appearance, causing severe distress and disability. Although BDD affects 1-2% of the population, the neurobiology is not understood. Discrepant results in previous volumetric studies may be due to small sample sizes, and no study has investigated cortical thickness in BDD. The current study is the largest neuroimaging analysis of BDD. Participants included 49 medication-free, right-handed individuals with DSM-IV BDD and 44 healthy controls matched by age, sex, and education. Using high-resolution T1-weighted magnetic resonance imaging, we computed vertex-wise gray matter (GM) thickness on the cortical surface and GM volume using voxel-based morphometry. We also computed volumes in cortical and subcortical regions of interest. In addition to group comparisons, we investigated associations with symptom severity, insight, and anxiety within the BDD group. In BDD, greater anxiety was significantly associated with thinner GM in the left superior temporal cortex and greater GM volume in the right caudate nucleus. There were no significant differences in cortical thickness, GM volume, or volumes in regions of interest between BDD and control subjects. Subtle associations with clinical symptoms may characterize brain morphometric patterns in BDD, rather than large group differences in brain structure. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  3. Volumetric accuracy of cone-beam computed tomography.

    PubMed

    Park, Cheol-Woo; Kim, Jin-Ho; Seo, Yu-Kyeong; Lee, Sae-Rom; Kang, Ju-Hee; Oh, Song-Hee; Kim, Gyu-Tae; Choi, Yong-Suk; Hwang, Eui-Hwan

    2017-09-01

    This study was performed to investigate the influence of object shape and distance from the center of the image on the volumetric accuracy of cone-beam computed tomography (CBCT) scans, according to different parameters of tube voltage and current. Four geometric objects (cylinder, cube, pyramid, and hexagon) with predefined dimensions were fabricated. The objects consisted of Teflon-perfluoroalkoxy embedded in a hydrocolloid matrix (Dupli-Coe-Loid TM; GC America Inc., Alsip, IL, USA), encased in an acrylic resin cylinder assembly. An Alphard Vega Dental CT system (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan) was used to acquire CBCT images. OnDemand 3D (CyberMed Inc., Seoul, Korea) software was used for object segmentation and image analysis. The accuracy was expressed by the volume error (VE). The VE was calculated under 3 different exposure settings. The measured volumes of the objects were compared to the true volumes for statistical analysis. The mean VE ranged from -4.47% to 2.35%. There was no significant relationship between an object's shape and the VE. A significant correlation was found between the distance of the object to the center of the image and the VE. Tube voltage affected the volume measurements and the VE, but tube current did not. The evaluated CBCT device provided satisfactory volume measurements. To assess volume measurements, it might be sufficient to use serial scans with a high resolution, but a low dose. This information may provide useful guidance for assessing volume measurements.

  4. Volumetric Analysis of Regional Cerebral Development in Preterm Children

    PubMed Central

    Kesler, Shelli R.; Ment, Laura R.; Vohr, Betty; Pajot, Sarah K.; Schneider, Karen C.; Katz, Karol H.; Ebbitt, Timothy B.; Duncan, Charles C.; Makuch, Robert W.; Reiss, Allan L.

    2011-01-01

    Preterm birth is frequently associated with both neuropathologic and cognitive sequelae. This study examined cortical lobe, subcortical, and lateral ventricle development in association with perinatal variables and cognitive outcome. High-resolution volumetric magnetic resonance imaging scans were acquired and quantified using advanced image processing techniques. Seventy-three preterm and 33 term control children ages 7.3-11.4 years were included in the study. Results indicated disproportionately enlarged parietal and frontal gray matter, occipital horn, and ventricular body, as well as reduced temporal and subcortical gray volumes in preterm children compared with control subjects. Birth weight was negatively correlated with parietal and frontal gray, as well as occipital horn volumes. Intraventricular hemorrhage was associated with reduced subcortical gray matter. Ventricular cerebrospinal fluid was negatively correlated with subcortical gray matter volumes but not with white matter volumes. Maternal education was the strongest predictor of cognitive function in the preterm group. Preterm birth appears to be associated with disorganized cortical development, possibly involving disrupted synaptic pruning and neural migration. Lower birth weight and the presence of intraventricular hemorrhage may increase the risk for neuroanatomic abnormality. PMID:15519112

  5. Skeletal muscle tissue engineering: strategies for volumetric constructs

    PubMed Central

    Cittadella Vigodarzere, Giorgio; Mantero, Sara

    2014-01-01

    Skeletal muscle tissue is characterized by high metabolic requirements, defined structure and high regenerative potential. As such, it constitutes an appealing platform for tissue engineering to address volumetric defects, as proven by recent works in this field. Several issues common to all engineered constructs constrain the variety of tissues that can be realized in vitro, principal among them the lack of a vascular system and the absence of reliable cell sources; as it is, the only successful tissue engineering constructs are not characterized by active function, present limited cellular survival at implantation and possess low metabolic requirements. Recently, functionally competent constructs have been engineered, with vascular structures supporting their metabolic requirements. In addition to the use of biochemical cues, physical means, mechanical stimulation and the application of electric tension have proven effective in stimulating the differentiation of cells and the maturation of the constructs; while the use of co-cultures provided fine control of cellular developments through paracrine activity. This review will provide a brief analysis of some of the most promising improvements in the field, with particular attention to the techniques that could prove easily transferable to other branches of tissue engineering. PMID:25295011

  6. Volumetric analysis of aeration in the lungs during general anaesthesia.

    PubMed

    Reber, A; Engberg, G; Sporre, B; Kviele, L; Rothen, H U; Wegenius, G; Nylund, U; Hedenstierna, G

    1996-06-01

    Spiral computed tomography (CT) allows volumetric analysis of formation of atelectasis and aeration of the lungs during anaesthesia. We studied 26 premedicated patients undergoing elective surgery allocated to group 1 (conscious, spontaneous breathing, investigating inspiration and expiration), group 2 (general anaesthesia with mechanical ventilation, investigating inspiration and expiration) or group 3 (general anaesthesia with mechanical ventilation, investigating changes over time). Using spiral CT, the lungs were studied either before or during general anaesthesia. CT scans were grouped into the following areas: overaeration, normal aeration, reduced aeration, poor aeration and atelectasis. The mechanism of atelectasis appeared to be both gravitational forces and a diaphragm-related force that acts regionally in caudal lung regions. Mean atelectasis formation and poorly aerated regions comprised approximately 4% of the total lung volume between the diaphragm and carina, giving a mean value of 16-20% of the normal aerated lung tissue being either collapsed or poorly aerated. The vertical ventilation distribution was more even during anaesthesia than in the awake state.

  7. Axial displacements in external and internal implant-abutment connection.

    PubMed

    Lee, Ji-Hye; Kim, Dae-Gon; Park, Chan-Jin; Cho, Lee-Ra

    2014-02-01

    The purpose of this study was to evaluate the axial displacement of the abutments during clinical procedures by the tightening torque and cyclic loading. Two different implant-abutment connection systems were used (external butt joint connection [EXT]; internal tapered conical connection [INT]). The master casts with two implant replicas, angulated 10° from each other, were fabricated for each implant connection system. Four types of impression copings were assembled and tightened with the corresponding implants (hex transfer impression coping, non-hex transfer impression coping, hex pick-up impression coping, non-hex pick-up impression coping). Resin splinted abutments and final prosthesis were assembled. The axial displacement was measured from the length of each assembly, which was evaluated repeatedly, after 30 Ncm torque tightening. After 250 N cyclic loading of final prosthesis for 1,000,000 cycles, additional axial displacement was recorded. The mean axial displacement was statistically analyzed (repeated measured ANOVA). There was more axial displacement in the INT group than that of the EXT group in impression copings, resin splinted abutments, and final prosthesis. Less axial displacement was found at 1-piece non-hex transfer type impression coping than other type of impression copings in the INT group. There was more axial displacement at the final prosthesis than resin splinted abutments in the INT and the EXT groups. After 250 N cyclic loading of final prosthesis, the INT group showed more axial displacement than that of the EXT group. Internal tapered conical connection demonstrated a varying amount of axial displacement with tightening torque and cyclic loading. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  8. Axial penile rigidity: determinants and relation to hemodynamic parameters.

    PubMed

    Goldstein, I; Udelson, D

    1998-05-01

    Erectile dysfunction may be defined in terms of axial penile rigidity, the physical property that enables the erection to be utilized as a penetration tool during sexual activity. Erectile dysfunction occurs when inadequate axial penile rigidity results in buckling of the penile column when subjected to axial compressive loading situations during vaginal intromission. New multi-disciplinary engineering studies of penile hemodynamic and structural dynamic relationships are reviewed concerning the determinants of axial penile rigidity. Axial penile rigidity develops as a continuum during the increases in intracavernosal pressure and volume changes from the flaccid state and is influenced by intracavernosal pressure, penile tissue mechanical properties and penile geometry. Two penile tissue mechanical properties are especially relevant; cavernosal maximum volume at relatively low intracavernosal pressure, and tunical distensibility, the relative volume of the fully erect to completely flaccid pendulous penis. Two penile geometric properties are critical; the penile aspect ratio, defined as the diameter to length ratio of the pendulous penis, and the magnitude of the flaccid penile diameter. Clinically measured values of axial buckling forces in patients undergoing dynamic pharmacocavernosometry strongly correlated to theoretic-based analytic derived magnitudes of axial penile rigidity based on these above pressure, tissue and geometric determinants. Since axial penile rigidity is not exclusively dependent upon intracavernosal pressure, patients with normal erectile hemodynamics may be erroneously labelled as having psychogenic dysfunction where their true pathophysiology may be related to abnormal penile tissue properties and/or penile geometric factors. Similarly, some patients may claim sufficient rigidity for penetration, but have abnormal hemodynamic erectile function studies. They may have uniquely advantageous tissue mechanical and/or geometric properties. More

  9. Identifying Axial Spondyloarthritis in Electronic Medical Records of US Veterans.

    PubMed

    Walsh, Jessica A; Shao, Yijun; Leng, Jianwei; He, Tao; Teng, Chia-Chen; Redd, Doug; Treitler Zeng, Qing; Burningham, Zachary; Clegg, Daniel O; Sauer, Brian C

    2017-09-01

    Large database research in axial spondyloarthritis (SpA) is limited by a lack of methods for identifying most types of axial SpA. Our objective was to develop methods for identifying axial SpA concepts in the free text of documents from electronic medical records. Veterans with documents in the national Veterans Health Administration Corporate Data Warehouse between January 1, 2005 and June 30, 2015 were included. Methods were developed for exploring, selecting, and extracting meaningful terms that were likely to represent axial SpA concepts. With annotation, clinical experts reviewed sections of text containing the meaningful terms (snippets) and classified the snippets according to whether or not they represented the intended axial SpA concept. With natural language processing (NLP) tools, computers were trained to replicate the clinical experts' snippet classifications. Three axial SpA concepts were selected by clinical experts, including sacroiliitis, terms including the prefix spond*, and HLA-B27 positivity (HLA-B27+). With supervised machine learning on annotated snippets, NLP models were developed with accuracies of 91.1% for sacroiliitis, 93.5% for spond*, and 97.2% for HLA-B27+. With independent validation, the accuracies were 92.0% for sacroiliitis, 91.0% for spond*, and 99.0% for HLA-B27+. We developed feasible and accurate methods for identifying axial SpA concepts in the free text of clinical notes. Additional research is required to determine combinations of concepts that will accurately identify axial SpA phenotypes. These novel methods will facilitate previously impractical observational research in axial SpA and may be applied to research with other diseases. © 2016, American College of Rheumatology.

  10. Historical variation of the geomagnetic axial dipole

    NASA Astrophysics Data System (ADS)

    Finlay, Christopher C.

    2008-09-01

    The geomagnetic axial dipole (hereinafter denoted g10) is the largest component of our planet's magnetic field. Its magnitude determines the morphology of solar-terrestrial electrical current systems and it is the most fundamental diagnostic property of the core-generated geodynamo. Elucidating past and future variations of g10(t) is consequently of central importance in geomagnetism. Previous historical geomagnetic field models, such as gufm1 of Jackson et al. [Jackson, A., Jonkers, A.R.T., Walker, M.R., 2000. Four centuries of geomagnetic secular variation from historical records. Philos. Trans. R. Soc. Lond. A 358, 957-990], used direct observations to constrain g10(t) only after 1840 A.D.; before this time a crude linear extrapolation of the post-1840 A.D. rate of change (15 nT/year) was employed. In this contribution I construct historical field models with g10(t) instead constrained from 1590 A.D. to 1840 A.D. by an archaeointensity dataset compiled by Korte et al. [Korte, M., Genevey, A., Constable, C.G., Frank, U., Schnepp, E., 2005. Continuous geomagnetic field models for the past 7 millennia. 1. A new global data compilation. Geochem. Geophys. Geosyst. 6, doi:10.1029/2004GC000800]. A range of possible linear models of the form g10(t)=g10(1840)+β(t-1840) are first explored; β=2.74±42.32 nT/year is found to explain the archaeointensity dataset with maximum likelihood, consistent with the recent findings of Gubbins et al. [Gubbins, D., Jones, A.L., Finlay, C.C., 2006. Fall in Earth's magnetic field is erratic. Science 312, 900-902]. Relaxing the linear constraint in an effort to find more physically plausible models, I find it is necessary to artificially increase the weight given to the archaeointensity data in order to obtain acceptable models. Despite satisfactorily explaining both the historical and archaeointensity data, and possessing reasonable spatial and temporal complexity, such free evolution models perform worse than the simpler linearly

  11. Nonmechanical axial scanning laser Doppler velocimeter with directional discrimination.

    PubMed

    Maru, Koichi; Hata, Takahiro

    2012-07-10

    An axial scanning laser Doppler velocimeter (LDV) with directional discrimination not requiring any moving mechanism in its probe is proposed. The proposed LDV utilizes frequency shift induced by acousto-optic modulators (AOMs) for discriminating the direction of velocity. The measurement position is axially scanned by changing the wavelength of the light input to the probe. The experimental result reveals that both the axial scan and the directional discrimination can be realized by using the proposed method without any moving element in the probe.

  12. A Model for Axial Magnetic Bearings Including Eddy Currents

    NASA Technical Reports Server (NTRS)

    Kucera, Ladislav; Ahrens, Markus

    1996-01-01

    This paper presents an analytical method of modelling eddy currents inside axial bearings. The problem is solved by dividing an axial bearing into elementary geometric forms, solving the Maxwell equations for these simplified geometries, defining boundary conditions and combining the geometries. The final result is an analytical solution for the flux, from which the impedance and the force of an axial bearing can be derived. Several impedance measurements have shown that the analytical solution can fit the measured data with a precision of approximately 5%.

  13. Fluorescence Axial Localization with Nanometer Accuracy and Precision

    SciTech Connect

    Li, Hui; Yen, Chi-Fu; Sivasankar, Sanjeevi

    2012-06-15

    We describe a new technique, standing wave axial nanometry (SWAN), to image the axial location of a single nanoscale fluorescent object with sub-nanometer accuracy and 3.7 nm precision. A standing wave, generated by positioning an atomic force microscope tip over a focused laser beam, is used to excite fluorescence; axial position is determined from the phase of the emission intensity. We use SWAN to measure the orientation of single DNA molecules of different lengths, grafted on surfaces with different functionalities.

  14. Axial magnetic effect in two-color quenched lattice QCD

    NASA Astrophysics Data System (ADS)

    Braguta, V.; Chernodub, M. N.; Goy, V. A.; Landsteiner, K.; Molochkov, A. V.; Polikarpov, M. I.

    2015-05-01

    The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T2 behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction.

  15. Axial magnetic effect in two-color quenched lattice QCD

    NASA Astrophysics Data System (ADS)

    Braguta, V.; Chernodub, M. N.; Goy, V. A.; Landsteiner, K.; Molochkov, A. V.; Polikarpov, M. I.

    2015-01-01

    The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T2 behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction.

  16. Revealing atropisomer axial chirality in drug discovery.

    PubMed

    LaPlante, Steven R; Edwards, Paul J; Fader, Lee D; Jakalian, Araz; Hucke, Oliver

    2011-03-07

    An often overlooked source of chirality is atropisomerism, which results from slow rotation along a bond axis due to steric hindrance and/or electronic factors. If undetected or not managed properly, this time-dependent chirality has the potential to lead to serious consequences, because atropisomers can be present as distinct enantiomers or diastereoisomers with their attendant different properties. Herein we introduce a strategy to reveal and classify compounds that have atropisomeric chirality. Energy barriers to axial rotation were calculated using quantum mechanics, from which predicted high barriers could be experimentally validated. A calculated rotational energy barrier of 20 kcal mol(-1) was established as a suitable threshold to distinguish between atropisomers and non-atropisomers with a prediction accuracy of 86%. This methodology was applied to subsets of drug databases in the course of which atropisomeric drugs were identified. In addition, some drugs were exposed that were not yet known to have this chiral attribute. The most valuable utility of this tool will be to predict atropisomerism along the drug discovery pathway. When used in concert with our compound classification scheme, decisions can be made during early discovery stages such as "hit-to-lead" and "lead optimization," to foresee and validate the presence of atropisomers and to exercise options of removing, further stabilizing, or rendering the chiral axis of interest more freely rotatable via SAR design, thereby decreasing this potential liability within a compound series. The strategy can also improve drug development plans, such as determining whether a drug or series should be developed as a racemic mixture or as an isolated single compound. Moreover, the work described herein can be extended to other chemical fields that require the assessment of potential chiral axes.

  17. High Power Co-Axial Coupler

    SciTech Connect

    Johnson, Rolland; Neubauer, Michael

    2013-08-14

    A superconducting RF (SRF) power coupler capable of handling 500 kW CW RF power at 750 MHz is required for present and future storage rings and linacs. There are over 35 coupler designs for SRF cavities ranging in frequency from 325 to 1500 MHz. Coupler windows vary from cylinders to cones to disks and RF power couplers will always be limited by the ability of ceramic windows and their matching systems to withstand the stresses due to non-uniform heating from dielectric and wall losses, multipactor, and mechanical flexure. In the Phase II project, we built a double window coaxial system with materials that would not otherwise be useable due to individual VSWRs. Double window systems can be operated such that one is cold (LN2) and one is warm. They can have different materials and still have a good match without using matching elements that create problematic multipactor bands. The match of the two windows will always result from the cancellation of the two window’s reflections when they are located approximately a quarter wavelength apart or multiples of a quarter wavelength. The window assemblies were carefully constructed to put the window material and its braze joint in compression at all times. This was done using explosion bonding techniques which allow for inexpensive fabrication of the vacuum / compression ring out of stainless steel with copper plating applied to the inner surface. The EIA 3-1/8” double window assembly was then successfully baked out and tested to 12 kW in a 3-1/8” co-axial system. The thermal gradient across the window was measured to be 90 C which represents about 15 ksi tensile stress in an uncompressed window. In our design the compression was calculated to be about 25 ksi, so the net compressive force was 5 ksi at full power.

  18. Line-tied MHD modes: effect of plasma pressure, axial boundary condition and axial flow

    NASA Astrophysics Data System (ADS)

    Arcudi, Francesco; Delzanno, Gian Luca; Finn, John M.

    2008-11-01

    Recent 3D nonlinear magnetohydrodynamic (MHD) simulations of astrophysical jets [1] showed a narrow jet-like region with very tightly wound magnetic fields, very suggestive of jet observations. These results were unexpected because such tightly wound magnetic fields should be violently MHD unstable. In order to make direct contact with the simulations of Ref. [1], we present a linear stability study in resistive MHD in cylindrical geometry. In this work, stability is studied including axial flows and finite plasma pressure. We also changed the axial boundary conditions to model those typical of astrophysical jets and laboratory experiments, using line-tying at one end of the field lines and non-line-tied boundary conditions at the other end [2]. The numerical results show that pressure strongly shifts the marginal stability threshold relative to the Kruskal-Shafranov threshold and a monotonically increasing pressure profile stabilizes the plasma. On the other hand, non-line-tied boundary conditions have little effect on marginal stability for typical parameters. All the results are supported by analytical studies based on reduced ideal MHD. [1] H. Li, G. Lapenta, J. M. Finn, S. Li, and S. A. Colgate, Astrophys. J. 643, 92 (2006). [2] D. D. Ryutov, I. Furno, T. P. Intrator, S. Abbate, and T. Madziwa-Nussinov, Phys. Plasmas 13, 032105 (2006).

  19. The Nonradiographic Axial Spondyloarthritis, the Radiographic Axial Spondyloarthritis, and Ankylosing Spondylitis: The Tangled Skein of Rheumatology

    PubMed Central

    Rawat, Roopa; Agrawal, Neha; Patil, Nilesh S.

    2017-01-01

    Since 1984 the diagnosis of ankylosing spondylitis (AS) has been based upon the modified New York (mNY) criteria with mandatory presence of radiographic sacroiliitis, without which the diagnosis is not tenable. However, it may take years or decades for radiographic sacroiliitis to develop delaying the diagnosis for long periods. It did not matter in the past because no effective treatment was available. However, with the availability of a highly effective treatment, namely, tumour necrosis factor-α inhibitors (TNFi), the issue of early diagnosis of AS acquired an urgency. The Assessment of SpondyloArthritis International Society (ASAS) classification criteria published in 2009 was a significant step towards this goal. These criteria described an early stage of the disease where sacroiliitis was demonstrable only on MRI but not on standard radiograph. Therefore, this stage of the disease was labelled “nonradiographic axial SpA” (nr-axSpA). But questions have been raised if, in search of early diagnosis, specificity was compromised. The Federal Drug Administration (FDA, USA) withheld approval for the use of TNFi in patients with nr-axSpA because of issues related to the specificity of these criteria. This review attempts to clarify some of these aspects of the nr-axSpA-AS relationship and also tries to answer the question whether ASAS classifiable radiographic axial spondyloarthritis (r-axSpA) term can be interchangeably used with the term AS. PMID:28555158

  20. On the Uncertain Future of the Volumetric 3D Display Paradigm

    NASA Astrophysics Data System (ADS)

    Blundell, Barry G.

    2017-06-01

    Volumetric displays permit electronically processed images to be depicted within a transparent physical volume and enable a range of cues to depth to be inherently associated with image content. Further, images can be viewed directly by multiple simultaneous observers who are able to change vantage positions in a natural way. On the basis of research to date, we assume that the technologies needed to implement useful volumetric displays able to support translucent image formation are available. Consequently, in this paper we review aspects of the volumetric paradigm and identify important issues which have, to date, precluded their successful commercialization. Potentially advantageous characteristics are outlined and demonstrate that significant research is still needed in order to overcome barriers which continue to hamper the effective exploitation of this display modality. Given the recent resurgence of interest in developing commercially viable general purpose volumetric systems, this discussion is of particular relevance.