Extracellular volume fraction mapping in the myocardium, part 1: evaluation of an automated method
Directory of Open Access Journals (Sweden)
Kellman Peter
2012-09-01
Full Text Available Abstract Background Disturbances in the myocardial extracellular volume fraction (ECV, such as diffuse or focal myocardial fibrosis or edema, are hallmarks of heart disease. Diffuse ECV changes are difficult to assess or quantify with cardiovascular magnetic resonance (CMR using conventional late gadolinium enhancement (LGE, or pre- or post-contrast T1-mapping alone. ECV measurement circumvents factors that confound T1-weighted images or T1-maps, and has been shown to correlate well with diffuse myocardial fibrosis. The goal of this study was to develop and evaluate an automated method for producing a pixel-wise map of ECV that would be adequately robust for clinical work flow. Methods ECV maps were automatically generated from T1-maps acquired pre- and post-contrast calibrated by blood hematocrit. The algorithm incorporates correction of respiratory motion that occurs due to insufficient breath-holding and due to misregistration between breath-holds, as well as automated identification of the blood pool. Images were visually scored on a 5-point scale from non-diagnostic (1 to excellent (5. Results The quality score of ECV maps was 4.23 ± 0.83 (m ± SD, scored for n = 600 maps from 338 patients with 83% either excellent or good. Co-registration of the pre-and post-contrast images improved the image quality for ECV maps in 81% of the cases. ECV of normal myocardium was 25.4 ± 2.5% (m ± SD using motion correction and co-registration values and was 31.5 ± 8.7% without motion correction and co-registration. Conclusions Fully automated motion correction and co-registration of breath-holds significantly improve the quality of ECV maps, thus making the generation of ECV-maps feasible for clinical work flow.
Extracellular volume fraction mapping in the myocardium, part 2: initial clinical experience.
Kellman, Peter; Wilson, Joel R; Xue, Hui; Bandettini, W Patricia; Shanbhag, Sujata M; Druey, Kirk M; Ugander, Martin; Arai, Andrew E
2012-09-11
Diffuse myocardial fibrosis, and to a lesser extent global myocardial edema, are important processes in heart disease which are difficult to assess or quantify with cardiovascular magnetic resonance (CMR) using conventional late gadolinium enhancement (LGE) or T1-mapping. Measurement of the myocardial extracellular volume fraction (ECV) circumvents factors that confound T1-weighted images or T1-maps. We hypothesized that quantitative assessment of myocardial ECV would be clinically useful for detecting both focal and diffuse myocardial abnormalities in a variety of common and uncommon heart diseases. A total of 156 subjects were imaged including 62 with normal findings, 33 patients with chronic myocardial infarction (MI), 33 with hypertrophic cardiomyopathy (HCM), 15 with non-ischemic dilated cardiomyopathy (DCM), 7 with acute myocarditis, 4 with cardiac amyloidosis, and 2 with systemic capillary leak syndrome (SCLS). Motion corrected ECV maps were generated automatically from T1-maps acquired pre- and post-contrast calibrated by blood hematocrit. Abnormally-elevated ECV was defined as >2SD from the mean ECV in individuals with normal findings. In HCM the size of regions of LGE was quantified as the region >2 SD from remote. Mean ECV of 62 normal individuals was 25.4 ± 2.5% (m ± SD), normal range 20.4%-30.4%. Mean ECV within the core of chronic myocardial infarctions (without MVO) (N=33) measured 68.5 ± 8.6% (pmapping appears promising to complement LGE imaging in cases of more homogenously diffuse disease. The ability to display ECV maps in units that are physiologically intuitive and may be interpreted on an absolute scale offers the potential for detection of diffuse disease and measurement of the extent and severity of abnormal regions.
Myocardial T1 and extracellular volume fraction mapping at 3 tesla.
Lee, Jason J; Liu, Songtao; Nacif, Marcelo S; Ugander, Martin; Han, Jing; Kawel, Nadine; Sibley, Christopher T; Kellman, Peter; Arai, Andrew E; Bluemke, David A
2011-11-28
To compare 11 heartbeat (HB) and 17 HB modified lock locker inversion recovery (MOLLI) pulse sequence at 3T and to establish preliminary reference values for myocardial T1 and the extracellular volume fraction (ECV). Both phantoms and normal volunteers were scanned at 3T using 11 HB and 17 HB MOLLI sequence with the following parameters: spatial resolution = 1.75 × 1.75 × 10 mm on a 256 × 180 matrix, TI initial = 110 ms, TI increment = 80 ms, flip angle = 35°, TR/TE = 1.9/1.0 ms. All volunteers were administered Gadolinium-DTPA (Magnevist, 0.15 mmol/kg), and multiple post-contrast MOLLI scans were performed at the same pre-contrast position from 3.5-23.5 minutes after a bolus contrast injection. Late gadolinium enhancement (LGE) images were also acquired 12-30 minutes after the gadolinium bolus. T1 values of 11 HB and 17 HB MOLLI displayed good agreement in both phantom and volunteers. The average pre-contrast myocardial and blood T1 was 1315 ± 39 ms and 2020 ± 129 ms, respectively. ECV was stable between 8.5 to 23.5 minutes post contrast with an average of 26.7 ± 1.0%. The 11 HB MOLLI is a faster method for high-resolution myocardial T1 mapping at 3T. ECV fractions are stable over a wide time range after contrast administration.
Mapping Bone Mineral Density Obtained by Quantitative Computed Tomography to Bone Volume Fraction
Pennline, James A.; Mulugeta, Lealem
2017-01-01
Methods for relating or mapping estimates of volumetric Bone Mineral Density (vBMD) obtained by Quantitative Computed Tomography to Bone Volume Fraction (BVF) are outlined mathematically. The methods are based on definitions of bone properties, cited experimental studies and regression relations derived from them for trabecular bone in the proximal femur. Using an experimental range of values in the intertrochanteric region obtained from male and female human subjects, age 18 to 49, the BVF values calculated from four different methods were compared to the experimental average and numerical range. The BVF values computed from the conversion method used data from two sources. One source provided pre bed rest vBMD values in the intertrochanteric region from 24 bed rest subject who participated in a 70 day study. Another source contained preflight vBMD values from 18 astronauts who spent 4 to 6 months on the ISS. To aid the use of a mapping from BMD to BVF, the discussion includes how to formulate them for purpose of computational modeling. An application of the conversions would be used to aid in modeling of time varying changes in vBMD as it relates to changes in BVF via bone remodeling and/or modeling.
Extracellular volume fraction mapping in the myocardium, part 2: initial clinical experience
2012-01-01
Background Diffuse myocardial fibrosis, and to a lesser extent global myocardial edema, are important processes in heart disease which are difficult to assess or quantify with cardiovascular magnetic resonance (CMR) using conventional late gadolinium enhancement (LGE) or T1-mapping. Measurement of the myocardial extracellular volume fraction (ECV) circumvents factors that confound T1-weighted images or T1-maps. We hypothesized that quantitative assessment of myocardial ECV would be clinically useful for detecting both focal and diffuse myocardial abnormalities in a variety of common and uncommon heart diseases. Methods A total of 156 subjects were imaged including 62 with normal findings, 33 patients with chronic myocardial infarction (MI), 33 with hypertrophic cardiomyopathy (HCM), 15 with non-ischemic dilated cardiomyopathy (DCM), 7 with acute myocarditis, 4 with cardiac amyloidosis, and 2 with systemic capillary leak syndrome (SCLS). Motion corrected ECV maps were generated automatically from T1-maps acquired pre- and post-contrast calibrated by blood hematocrit. Abnormally-elevated ECV was defined as >2SD from the mean ECV in individuals with normal findings. In HCM the size of regions of LGE was quantified as the region >2 SD from remote. Results Mean ECV of 62 normal individuals was 25.4 ± 2.5% (m ± SD), normal range 20.4%-30.4%. Mean ECV within the core of chronic myocardial infarctions (without MVO) (N = 33) measured 68.5 ± 8.6% (p ECV correlated to the extent of LGE (r = 0.72, p ECV (mean difference 19 ± 7% of slice). Abnormally elevated ECV was identified in 4 of 16 patients with non-ischemic DCM (38.1 ± 1.9% (p ECV values in other disease entities ranged 32-60% for cardiac amyloidosis (N = 4), 40-41% for systemic capillary leak syndrome (N = 2), and 39-56% within abnormal regions affected by myocarditis (N = 7). Conclusions ECV mapping appears promising to complement LGE imaging in cases of more
Myocardial T1 and extracellular volume fraction mapping at 3 tesla
Directory of Open Access Journals (Sweden)
Lee Jason J
2011-11-01
Full Text Available Abstract Background To compare 11 heartbeat (HB and 17 HB modified lock locker inversion recovery (MOLLI pulse sequence at 3T and to establish preliminary reference values for myocardial T1 and the extracellular volume fraction (ECV. Methods Both phantoms and normal volunteers were scanned at 3T using 11 HB and 17 HB MOLLI sequence with the following parameters: spatial resolution = 1.75 × 1.75 × 10 mm on a 256 × 180 matrix, TI initial = 110 ms, TI increment = 80 ms, flip angle = 35°, TR/TE = 1.9/1.0 ms. All volunteers were administered Gadolinium-DTPA (Magnevist, 0.15 mmol/kg, and multiple post-contrast MOLLI scans were performed at the same pre-contrast position from 3.5-23.5 minutes after a bolus contrast injection. Late gadolinium enhancement (LGE images were also acquired 12-30 minutes after the gadolinium bolus. Results T1 values of 11 HB and 17 HB MOLLI displayed good agreement in both phantom and volunteers. The average pre-contrast myocardial and blood T1 was 1315 ± 39 ms and 2020 ± 129 ms, respectively. ECV was stable between 8.5 to 23.5 minutes post contrast with an average of 26.7 ± 1.0%. Conclusion The 11 HB MOLLI is a faster method for high-resolution myocardial T1 mapping at 3T. ECV fractions are stable over a wide time range after contrast administration.
Roller, F C; Harth, S; Schneider, C; Krombach, G A
2015-09-01
Cardiac magnetic resonance imaging (CMRI) is a versatile diagnostic tool. One of its main advantages is the possibility of tissue characterization. T1-weighted images for scar and T2-weighted images for edema visualization are key methods for tissue characterization. Otherwise these sequences are strongly limited for the detection of diffuse myocardial pathologies. Recently, rapid technical innovations have generated new techniques. T1, T2 mapping and evaluation of the extracellular volume fraction (ECV) allow quantification of diffuse myocardial pathologies and showed great potential in the visualization of fibrosis, edema, amyloid, iron overload and lipid. In the future these techniques might enable the detection of early cardiac involvement, even act as a prognosticator. Moreover, therapy monitoring and follow-up might be possible due to versatile parameter quantification with these new techniques. CMR allows for tissue characterization via T1- and T2-weighted sequences. In cases of diffuse, global myocardial pathologies, correct image interpretation with traditional CMR sequences might be difficult. T1, T2 mapping and ECV can quantify diffuse, global myocardial pathologies. Alterations of myocardial T1 and T2 relaxation times occur in various myocardial diseases (e.g. acute myocarditis). In the future mapping might act as a prognosticator or therapy monitoring tool. © Georg Thieme Verlag KG Stuttgart · New York.
Al-Wakeel-Marquard, Nadya; Rastin, Sanaz; Muench, Frédéric; O H-Ici, Darach; Yilmaz, Sevim; Berger, Felix; Kuehne, Titus; Messroghli, Daniel R
2017-12-01
Myocardial extracellular volume fraction (ECV) reflecting diffuse myocardial fibrosis can be measured with T1 mapping cardiovascular magnetic resonance (CMR) before and after the application of a gadolinium-based extracellular contrast agent. The equilibrium between blood and myocardium contrast concentration required for ECV measurements can be obtained with a primed contrast infusion (equilibrium contrast-CMR). We hypothesized that equilibrium can also be achieved with a single contrast bolus to accurately measure diffuse myocardial fibrosis in patients with congenital heart disease (CHD). Healthy controls (n = 17; median age 24.0 years) and patients with CHD (n = 19; 25.0 years) were prospectively enrolled. Using modified Look-Locker inversion recovery T1 mapping before, 15 min after bolus injection, and during constant infusion of gadolinium-DOTA, T1 values were obtained for blood pool and myocardium of the left ventricle (LV), the interventricular septum (IVS), and the right ventricle (RV) in a single midventricular plane in short axis or in transverse orientation. ECV of LV, IVS and RV by bolus-only and bolus-infusion correlated significantly in CHD patients (r = 0.94, 0.95, and 0.74; p < 0.01, respectively) and healthy controls (r = 0.96, 0.89, and 0.64; p < 0.05, respectively). Bland-Altman plots revealed no significant bias between the techniques for any of the analyzed regions. ECV of LV and RV myocardium measured by bolus-only T1 mapping agrees well with bolus-infusion measurements in patients with CHD. The use of a bolus-only approach facilitates the integration of ECV measurements into existing CMR imaging protocols, allowing for assessment of diffuse myocardial fibrosis in CHD in clinical routine.
Perea, Rosario J; Morales-Ruiz, Manuel; Ortiz-Perez, Jose T; Bosch, Xavier; Andreu, David; Borras, Roger; Acosta, Juan; Penela, Diego; Prat-González, Susanna; de Caralt, Teresa M; Martínez, Mikel; Morales-Romero, Blai; Lasalvia, Luis; Donnelly, James; Jiménez, Wladimiro; Mira, Aurea; Mont, Lluis; Berruezo, Antonio
2016-11-15
ST-segment elevation myocardial infarction (STEMI) triggers remote extracellular matrix expansion. Myocardial extracellular volume fraction (ECV), determined by cardiovascular magnetic resonance, permits quantification of interstitial space expansion. Our aim was to determine the relationship between early serum fibrosis biomarkers and 180-day post-infarct remote myocardium remodeling using ECV. In 26 patients with STEMI, functional imaging, T1-mapping, and late-gadolinium-enhancement were performed on a 3-T CMR scanner at baseline (days 3 to 5) and 180days. Biomarkers were measured at days 1, 3, and 7 after STEMI. The mean initial and follow-up left ventricular ejection fraction (LVEF) were 48.3±18.1% and 52.6±12.3%, respectively. Initial infarct size was 11.6±16.8% of LV mass. ECV in the remote myocardium at 180days correlated with indexed end-systolic volume (r=0.4, p=0.045). A significant correlation was observed between galectin-3 at day 7 and ECV at 6months (r=0.428, p=0.037). A trend towards a direct correlation was found for BNP (r=0.380, p=0.059). Multivariate analysis revealed that BNP and galectin-3 were independent predictors of long-term changes in ECV and explained nearly 30% of the variance in this parameter (r 2 =0.34; p=0.01). A galectin-3 cutoff value of 10.15ng/mL was the most powerful predictor of high ECV values (≥28.5%) at follow-up. Galectin-3 at day 7 was an independent predictor of high ECV values at follow-up (OR=22.51; CI 95%: 2.1-240.72; p=0.01) with 0.76 AUC (CI: 0.574-0.964; p=0.03). Galectin-3 measured acutely after STEMI is an independent predictor of increased ECV at 6-month follow-up that might be useful for long-term risk stratification. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Vassiliou, Vassilios S; Wassilew, Katharina; Cameron, Donnie; Heng, Ee Ling; Nyktari, Evangelia; Asimakopoulos, George; de Souza, Anthony; Giri, Shivraman; Pierce, Iain; Jabbour, Andrew; Firmin, David; Frenneaux, Michael; Gatehouse, Peter; Pennell, Dudley J; Prasad, Sanjay K
2018-02-01
Our objectives involved identifying whether repeated averaging in basal and mid left ventricular myocardial levels improves precision and correlation with collagen volume fraction for 11 heartbeat MOLLI T 1 mapping versus assessment at a single ventricular level. For assessment of T 1 mapping precision, a cohort of 15 healthy volunteers underwent two CMR scans on separate days using an 11 heartbeat MOLLI with a 5(3)3 beat scheme to measure native T 1 and a 4(1)3(1)2 beat post-contrast scheme to measure post-contrast T 1 , allowing calculation of partition coefficient and ECV. To assess correlation of T 1 mapping with collagen volume fraction, a separate cohort of ten aortic stenosis patients scheduled to undergo surgery underwent one CMR scan with this 11 heartbeat MOLLI scheme, followed by intraoperative tru-cut myocardial biopsy. Six models of myocardial diffuse fibrosis assessment were established with incremental inclusion of imaging by averaging of the basal and mid-myocardial left ventricular levels, and each model was assessed for precision and correlation with collagen volume fraction. A model using 11 heart beat MOLLI imaging of two basal and two mid ventricular level averaged T 1 maps provided improved precision (Intraclass correlation 0.93 vs 0.84) and correlation with histology (R 2 = 0.83 vs 0.36) for diffuse fibrosis compared to a single mid-ventricular level alone. ECV was more precise and correlated better than native T 1 mapping. T 1 mapping sequences with repeated averaging could be considered for applications of 11 heartbeat MOLLI, especially when small changes in native T 1 /ECV might affect clinical management.
Roller, Fritz C; Wiedenroth, Christoph; Breithecker, Andreas; Liebetrau, Christoph; Mayer, Eckhard; Schneider, Christian; Rolf, Andreas; Hamm, Christian; Krombach, Gabriele A
2017-05-01
The aim of this study was to assess septal and right ventricular insertion point (RVIP) fibrosis in patients with chronic thromboembolic pulmonary hypertension (CTEPH) via native T1 mapping and extracellular volume fraction (ECV) determination and to analyze correlations with functional parameters. Imaging was performed at 1.5 Tesla in 24 patients diagnosed with CTEPH and 24 controls. T1 values were measured within the septal myocardium, the upper and lower RVIP, and the lateral wall at basal short axis section. The mean septal native T1 values were 1012.8 ms ± 50.5 in the CTEPH group and 956.9 ms ± 24.4 in controls (p T1 showed a strong negative correlation with right ventricular ejection fraction (k = -0.92; p = 0.01). We conclude that native T1 mapping and ECV assessment enable visualization and quantification of septal fibrosis in CTEPH patients. The results also correlate well with right ventricular ejection fraction. Therefore, these parameters might be useful for prognosis and as therapy-monitoring tool in the future. • Septal native T1 and ECV values are significantly higher in CTEPH patients. • Native T1 and ECV values are elevated even in absence of LGE. • These techniques therefore enable an improved quantification of septal fibrosis in CTEPH. • Native T1 values also correlate well with right ventricular EF and PA-pressure. • Prognosis and therapy-monitoring might be assessable in the future with these parameters.
Florian, Anca; Ludwig, Anna; Rösch, Sabine; Yildiz, Handan; Sechtem, Udo; Yilmaz, Ali
2014-09-01
Cardiac involvement with progressive myocardial fibrosis leading to dilated cardiomyopathy is a major cause of death in muscular dystrophy patients. Extracellular volume fraction (ECV) measurement based on T1-mapping pre- and post-contrast promises the detection of early 'diffuse' myocardial fibrosis that cannot be depicted by conventional contrast-imaging based on late gadolinium enhancement (LGE). With this study, we evaluated the presence of diffuse myocardial fibrosis in regions of 'normal' (LGE-negative) and 'diseased' (LGE-positive) appearing myocardium as well as its relation to the extent of left ventricular (LV) dysfunction and the occurrence of arrhythmias in Becker muscular dystrophy (BMD) patients. Twenty-seven BMD patients (35 ± 12 years) and 17 matched male healthy controls (33 ± 8 years) underwent cardiovascular magnetic resonance (CMR) studies including ECV measurement and LGE-imaging. Ambulatory monitoring of arrhythmic events was performed by means of an external event loop recorder. Twenty BMD patients (74%) demonstrated cardiac involvement as detected by typical inferolateral presence of LGE. Twelve patients (44%) had an impaired LV ejection fraction-all being LGE-positive. Global myocardial ECV was significantly higher in the BMD group (29 ± 6%) compared with the control group (24 ± 2%, P = 0.001). Patients with cardiac involvement demonstrated higher global ECV (31 ± 6%) as well as significantly increased regional ECV not only in LGE-positive segments (34 ± 6%), but also in LGE-negative segments (28 ± 6%) compared with BMD patients without cardiac involvement and to controls, respectively (24 ± 3 and 24 ± 2%, P = 0.005). Global ECV in patients with cardiac involvement substantially correlated to LV ejection fraction (r = -0.629, P = 0.003) and to the number of LGE-positive segments (r = 0.783, P ECV-but not the categorical presence of LGE per se--was significantly associated with arrhythmic events (OR: 1.97, CI: 32.22-1.21, P = 0
Bulluck, Heerajnarain; Rosmini, Stefania; Abdel-Gadir, Amna; White, Steven K; Bhuva, Anish N; Treibel, Thomas A; Fontana, Marianna; Gonzalez-Lopez, Esther; Reant, Patricia; Ramlall, Manish; Hamarneh, Ashraf; Sirker, Alex; Herrey, Anna S; Manisty, Charlotte; Yellon, Derek M; Kellman, Peter; Moon, James C; Hausenloy, Derek J
2016-07-11
Whether the remote myocardium of reperfused ST-segment elevation myocardial infarction (STEMI) patients plays a part in adverse left ventricular (LV) remodeling remains unclear. We aimed to use automated extracellular volume fraction (ECV) mapping to investigate whether changes in the ECV of the remote (ECVR emote) and infarcted myocardium (ECVI nfarct) impacted LV remodeling. Forty-eight of 50 prospectively recruited reperfused STEMI patients completed a cardiovascular magnetic resonance at 4±2 days and 40 had a follow-up scan at 5±2 months. Twenty healthy volunteers served as controls. Mean segmental values for native T1, T2, and ECV were obtained. Adverse LV remodeling was defined as ≥20% increase in LV end-diastolic volume. ECVR emote was higher on the acute scan when compared to control (27.9±2.1% vs 26.4±2.1%; P=0.01). Eight patients developed adverse LV remodeling and had higher ECVR emote acutely (29.5±1.4% vs 27.4±2.0%; P=0.01) and remained higher at follow-up (28.6±1.5% vs 26.6±2.1%; P=0.02) compared to those without. Patients with a higher ECVR emote and a lower myocardial salvage index (MSI) acutely were significantly associated with adverse LV remodeling, independent of T1Remote, T1Core and microvascular obstruction, whereas a higher ECVI nfarct was significantly associated with worse wall motion recovery. ECVR emote was increased acutely in reperfused STEMI patients. Those with adverse LV remodeling had higher ECVR emote acutely, and this remained higher at follow-up than those without adverse LV remodeling. A higher ECVR emote and a lower MSI acutely were significantly associated with adverse LV remodeling whereas segments with higher ECVI nfarct were less likely to recover wall motion. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.
Extracellular volume fractions in chronic myocardial infarction.
Bauner, Kerstin Ulrike; Biffar, Andreas; Theisen, Daniel; Greiser, Andreas; Zech, Christoph Johannes; Nguyen, Elsie T; Reiser, Maximilian F; Wintersperger, Bernd J
2012-09-01
The aim of this study was to assess and delineate chronic myocardial infarction (CMI) using precontrast and postcontrast T1 mapping techniques including quantification of extracellular volume fractions (ECVs). A total of 26 patients with CMI were examined at 1.5 T applying a modified Look-Locker Inversion Recovery sequence before and 10 minutes after contrast at 3 short-axis slice positions. An inversion recovery gradient recalled echo sequence (standard of reference) was used for imaging late gadolinium enhancement. Precontrast and postcontrast T1 maps were calculated, and CMI was defined as areas with T1 values more than 3 SDs different compared with normal myocardium (MYO). T1 values of CMI, MYO, and blood pool were measured, and ECVs of CMI and MYO were calculated. Two-tailed Student t test was used for statistical analysis of T1 values and ECVs. Sensitivities and specificities for detection of CMI on precontrast and postcontrast T1 maps were calculated. Receiver operating characteristic (ROC) analysis was performed for postcontrast T1 values and ECV for discrimination of CMI. The comparison of T1 values of CMI and MYO revealed significant differences in precontrast and postcontrast scans (1159 ± 64 vs 1001 ± 47 milliseconds, P T1 mapping were 41.7% and 100% in precontrast Look-Locker Inversion Recovery scans and 95.8% and 99.3% in postcontrast images, respectively. Average ECV for MYO and CMI were 28% ± 5% and 53% ± 10% (P T1 values and ECV, respectively (P = 0.137). Sensitivities and specificities were 92.3% and 92.3% for detecting CMI by postcontrast T1 values and 95.5% and 100% for ECV, with cutoff values being 305 milliseconds or less and greater than 42%. Combined criteria did not result in any further improvement of sensitivity for CMI detection. Postcontrast T1 values and ECV of chronically infarcted MYO are significantly different compared with respective values of normal MYO. Both parameters allow for accurate detection of CMI with ECV showing
Energy Technology Data Exchange (ETDEWEB)
Youn, Jong-Chan [Hallym University College of Medicine, Division of Cardiology, Dongtan Sacred Heart Hospital, Hwaseong (Korea, Republic of); Yonsei University College of Medicine, Division of Cardiology, Severance Cardiovascular Hospital, Seoul (Korea, Republic of); Hong, Yoo Jin; Lee, Hye-Jeong; Han, Kyunghwa; Suh, Young Joo; Hur, Jin; Kim, Young Jin; Choi, Byoung Wook [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Seoul (Korea, Republic of); Shim, Chi Young; Hong, Geu-Ru; Kang, Seok-Min [Yonsei University College of Medicine, Division of Cardiology, Severance Cardiovascular Hospital, Seoul (Korea, Republic of)
2017-09-15
We aimed to evaluate the prognostic role of cardiac magnetic resonance imaging (CMR)-based extracellular volume fraction (ECV) in patients with non-ischemic dilated cardiomyopathy (NIDCM) and compare it with late gadolinium enhancement (LGE) parameters. This was a single-center, prospective, cohort study of 117 NIDCM patients (71 men, 51.9 ± 16.7 years) who underwent clinical 3.0-T CMR. Myocardial ECV and LGE were quantified on the left ventricular myocardium. The presence of midwall LGE was also detected. Nineteen healthy subjects served as controls. The primary end points were cardiovascular (CV) events defined by CV death, rehospitalization due to heart failure, and heart transplantation. During the follow-up period (median duration, 11.2 months; 25{sup th}-75{sup th} percentile, 7.8-21.9 months), the primary end points occurred in 19 patients (16.2%). The ECV (per 3% and 1% increase) was associated with a hazard ratio of 1.80 and 1.22 (95% confidence interval [CI], 1.48-2.20 and 1.14-1.30, respectively; p < 0.001) for the CV events. Multivariable analysis also indicated that ECV was an independent prognostic factor and had a higher prognostic value (Harrell's c statistic, 0.88) than LGE quantification values (0.77) or midwall LGE (0.80). CMR-based ECV independently predicts the clinical outcome in NIDCM patients. (orig.)
Rommel, Karl-Philipp; von Roeder, Maximilian; Latuscynski, Konrad; Oberueck, Christian; Blazek, Stephan; Fengler, Karl; Besler, Christian; Sandri, Marcus; Lücke, Christian; Gutberlet, Matthias; Linke, Axel; Schuler, Gerhard; Lurz, Philipp
2016-04-19
Optimal patient characterization in heart failure with preserved ejection fraction (HFpEF) is essential to tailor successful treatment strategies. Cardiac magnetic resonance (CMR)-derived T1 mapping can noninvasively quantify diffuse myocardial fibrosis as extracellular volume fraction (ECV). This study aimed to elucidate the diagnostic performance of T1 mapping in HFpEF by examining the relationship between ECV and invasively measured parameters of diastolic function. It also investigated the potential of ECV to differentiate among pathomechanisms in HFpEF. We performed T1 mapping in 24 patients with HFpEF and 12 patients without heart failure symptoms. Pressure-volume loops were obtained with a conductance catheter during basal conditions and handgrip exercise. Transient pre-load reduction was used to extrapolate the diastolic stiffness constant. Patients with HFpEF showed higher ECV (p Heart Failure With Preserved Ejection Fraction [STIFFMAP]; NCT02459626). Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Kim, Yong Pyo; Kannengiesser, Stephan; Paek, Mun-Young; Kim, Sungjun; Chung, Tae-Sub; Yoo, Yeon Hwa; Yoon, Choon-Sik; Song, Ho-Taek; Lee, Young Han; Suh, Jin-Suck
2014-01-01
To assess the feasibility of T2*-corrected fat-signal fraction (FF) map by using the three-echo volume interpolated breath-hold gradient echo (VIBE) Dixon sequence to differentiate between malignant marrow-replacing lesions and benign red marrow deposition of vertebrae. We assessed 32 lesions from 32 patients who underwent magnetic resonance imaging after being referred for assessment of a known or possible vertebral marrow abnormality. The lesions were divided into 21 malignant marrow-replacing lesions and 11 benign red marrow depositions. Three sequences for the parameter measurements were obtained by using a 1.5-T MR imaging scanner as follows: three-echo VIBE Dixon sequence for FF; conventional T1-weighted imaging for the lesion-disc ratio (LDR); pre- and post-gadolinium enhanced fat-suppressed T1-weighted images for the contrast-enhancement ratio (CER). A region of interest was drawn for each lesion for parameter measurements. The areas under the curve (AUC) of the parameters and their sensitivities and specificities at the most ideal cutoff values from receiver operating characteristic curve analysis were obtained. AUC, sensitivity, and specificity were respectively compared between FF and CER. The AUCs of FF, LDR, and CER were 0.96, 0.80, and 0.72, respectively. In the comparison of diagnostic performance between the FF and CER, the FF showed a significantly larger AUC as compared to the CER (p = 0.030), although the difference of sensitivity (p = 0.157) and specificity (p = 0.157) were not significant. Fat-signal fraction measurement using T2*-corrected three-echo VIBE Dixon sequence is feasible and has a more accurate diagnostic performance, than the CER, in distinguishing benign red marrow deposition from malignant bone marrow-replacing lesions.
Directory of Open Access Journals (Sweden)
Kawel Nadine
2012-04-01
Full Text Available Abstract Purpose Myocardial T1 relaxation time (T1 time and extracellular volume fraction (ECV are altered in patients with diffuse myocardial fibrosis. The purpose of this study was to perform an intra-individual assessment of normal T1 time and ECV for two different contrast agents. Methods A modified Look-Locker Inversion Recovery (MOLLI sequence was acquired at 3 T in 24 healthy subjects (8 men; 28 ± 6 years at mid-ventricular short axis pre-contrast and every 5 min between 5-45 min after injection of a bolus of 0.15 mmol/kg gadopentetate dimeglumine (Gd-DTPA; Magnevist® (exam 1 and 0.1 mmol/kg gadobenate dimeglumine (Gd-BOPTA; Multihance® (exam 2 during two separate scanning sessions. T1 times were measured in myocardium and blood on generated T1 maps. ECVs were calculated as ΔR1myocardium/ΔR1blood*1−hematocrit. Results Mean pre-contrast T1 relaxation times for myocardium and blood were similar for both the first and second CMR exam (p > 0.5. Overall mean post-contrast myocardial T1 time was 15 ± 2 ms (2.5 ± 0.7% shorter for Gd-DTPA at 0.15 mmol/kg compared to Gd-BOPTA at 0.1 mmol/kg (p 0.05. Between 5 and 45 minutes after contrast injection, mean ECV values increased linearly with time for both contrast agents from 0.27 ± 0.03 to 0.30 ± 0.03 (p pre-contrast myocardial T1 relaxation time (CV 4.5% [exam 1] and 3.0% [exam 2], respectively. ECV with Gd-DTPA was highly correlated to ECV by Gd-BOPTA (r = 0.803; p Conclusion In comparison to pre-contrast myocardial T1 relaxation time, variation in ECV values of normal subjects is larger. However, absolute differences in ECV between Gd-DTPA and Gd-BOPTA were small and rank correlation was high. There is a small and linear increase in ECV over time, therefore ideally images should be acquired at the same delay after contrast injection.
Kawel, Nadine; Nacif, Marcelo; Zavodni, Anna; Jones, Jacquin; Liu, Songtao; Sibley, Christopher T; Bluemke, David A
2012-04-28
Myocardial T1 relaxation time (T1 time) and extracellular volume fraction (ECV) are altered in patients with diffuse myocardial fibrosis. The purpose of this study was to perform an intra-individual assessment of normal T1 time and ECV for two different contrast agents. A modified Look-Locker Inversion Recovery (MOLLI) sequence was acquired at 3 T in 24 healthy subjects (8 men; 28 ± 6 years) at mid-ventricular short axis pre-contrast and every 5 min between 5-45 min after injection of a bolus of 0.15 mmol/kg gadopentetate dimeglumine (Gd-DTPA; Magnevist®) (exam 1) and 0.1 mmol/kg gadobenate dimeglumine (Gd-BOPTA; Multihance®) (exam 2) during two separate scanning sessions. T1 times were measured in myocardium and blood on generated T1 maps. ECVs were calculated as ΔR1 myocardium/ΔR1 blood*1-hematocrit. Mean pre-contrast T1 relaxation times for myocardium and blood were similar for both the first and second CMR exam (p > 0.5). Overall mean post-contrast myocardial T1 time was 15 ± 2 ms (2.5 ± 0.7%) shorter for Gd-DTPA at 0.15 mmol/kg compared to Gd-BOPTA at 0.1 mmol/kg (p T1 time of blood pool (p > 0.05). Between 5 and 45 minutes after contrast injection, mean ECV values increased linearly with time for both contrast agents from 0.27 ± 0.03 to 0.30 ± 0.03 (p T1 relaxation time (CV 4.5% [exam 1] and 3.0% [exam 2], respectively). ECV with Gd-DTPA was highly correlated to ECV by Gd-BOPTA (r = 0.803; p T1 relaxation time, variation in ECV values of normal subjects is larger. However, absolute differences in ECV between Gd-DTPA and Gd-BOPTA were small and rank correlation was high. There is a small and linear increase in ECV over time, therefore ideally images should be acquired at the same delay after contrast injection.
2012-01-01
Purpose Myocardial T1 relaxation time (T1 time) and extracellular volume fraction (ECV) are altered in patients with diffuse myocardial fibrosis. The purpose of this study was to perform an intra-individual assessment of normal T1 time and ECV for two different contrast agents. Methods A modified Look-Locker Inversion Recovery (MOLLI) sequence was acquired at 3 T in 24 healthy subjects (8 men; 28 ± 6 years) at mid-ventricular short axis pre-contrast and every 5 min between 5-45 min after injection of a bolus of 0.15 mmol/kg gadopentetate dimeglumine (Gd-DTPA; Magnevist®) (exam 1) and 0.1 mmol/kg gadobenate dimeglumine (Gd-BOPTA; Multihance®) (exam 2) during two separate scanning sessions. T1 times were measured in myocardium and blood on generated T1 maps. ECVs were calculated as ΔR1myocardium/ΔR1blood*1−hematocrit. Results Mean pre-contrast T1 relaxation times for myocardium and blood were similar for both the first and second CMR exam (p > 0.5). Overall mean post-contrast myocardial T1 time was 15 ± 2 ms (2.5 ± 0.7%) shorter for Gd-DTPA at 0.15 mmol/kg compared to Gd-BOPTA at 0.1 mmol/kg (p 0.05). Between 5 and 45 minutes after contrast injection, mean ECV values increased linearly with time for both contrast agents from 0.27 ± 0.03 to 0.30 ± 0.03 (p < 0.0001). Mean ECV values were slightly higher (by 0.01, p < 0.05) for Gd-DTPA compared to Gd-BOPTA. Inter-individual variation of ECV was higher (CV 8.7% [exam 1, Gd-DTPA] and 9.4% [exam 2, Gd-BOPTA], respectively) compared to variation of pre-contrast myocardial T1 relaxation time (CV 4.5% [exam 1] and 3.0% [exam 2], respectively). ECV with Gd-DTPA was highly correlated to ECV by Gd-BOPTA (r = 0.803; p < 0.0001). Conclusion In comparison to pre-contrast myocardial T1 relaxation time, variation in ECV values of normal subjects is larger. However, absolute differences in ECV between Gd-DTPA and Gd-BOPTA were small and rank correlation was high. There is a small
Fractional-Step, Finite-Volume Computation Of Flow
Kwak, Dochan; Rosenfeld, Moshe; Vinokur, Marcel
1992-01-01
Method of solving Navier-Stokes equations of incompressible flow in general nonorthogonal curvilinear coordinates incorporates fractional-step and finite-volume approaches. Developed in continuing effort to achieve accuracy without need for excessive computation time in numerical simulation of time-dependent, three-dimensional flows bounded by surfaces of complicated shape.
Effect of reinforcement volume fraction on the density & elastic ...
African Journals Online (AJOL)
It was found the elastic moduli of high volume fraction composites are improved with the introduction of certain materials reinforcement such as Mo, Pt, Cr, Fe, U, etc. However, they decrease with some other materials reinforcements, as in the case of glass E and Cd. Moreover, we showed that the densities and elastic ...
Fractional labelmaps for computing accurate dose volume histograms
Sunderland, Kyle; Pinter, Csaba; Lasso, Andras; Fichtinger, Gabor
2017-03-01
PURPOSE: In radiation therapy treatment planning systems, structures are represented as parallel 2D contours. For treatment planning algorithms, structures must be converted into labelmap (i.e. 3D image denoting structure inside/outside) representations. This is often done by triangulated a surface from contours, which is converted into a binary labelmap. This surface to binary labelmap conversion can cause large errors in small structures. Binary labelmaps are often represented using one byte per voxel, meaning a large amount of memory is unused. Our goal is to develop a fractional labelmap representation containing non-binary values, allowing more information to be stored in the same amount of memory. METHODS: We implemented an algorithm in 3D Slicer, which converts surfaces to fractional labelmaps by creating 216 binary labelmaps, changing the labelmap origin on each iteration. The binary labelmap values are summed to create the fractional labelmap. In addition, an algorithm is implemented in the SlicerRT toolkit that calculates dose volume histograms (DVH) using fractional labelmaps. RESULTS: We found that with manually segmented RANDO head and neck structures, fractional labelmaps represented structure volume up to 19.07% (average 6.81%) more accurately than binary labelmaps, while occupying the same amount of memory. When compared to baseline DVH from treatment planning software, DVH from fractional labelmaps had agreement acceptance percent (1% ΔD, 1% ΔV) up to 57.46% higher (average 4.33%) than DVH from binary labelmaps. CONCLUSION: Fractional labelmaps promise to be an effective method for structure representation, allowing considerably more information to be stored in the same amount of memory.
Dynamical evolution of volume fractions in multipressure multiphase flow models.
Chang, C H; Ramshaw, J D
2008-06-01
Compared to single-pressure models, multipressure multiphase flow models require additional closure relations to determine the individual pressures of the different phases. These relations are often taken to be evolution equations for the volume fractions. We present a rigorous theoretical framework for constructing such equations for compressible multiphase mixtures in terms of submodels for the relative volumetric expansion rates DeltaE_{i} of the phases. These quantities are essentially the rates at which the phases dynamically expand or contract in response to pressure differences, and represent the general tendency of the volume fractions to relax toward values that produce local pressure equilibrium. We present a simple provisional model of this type in which DeltaE_{i} is proportional to pressure differences divided by the time required for sound waves to traverse an appropriate characteristic length. It is shown that the resulting approach to pressure equilibrium is monotonic rather than oscillatory, and occurs instantaneously in the incompressible limit.
Method and apparatus for probing relative volume fractions
Energy Technology Data Exchange (ETDEWEB)
Jandrasits, W.G.; Kikta, T.J.
1996-12-31
A relative volume fraction probe particularly for use in a multiphase fluid system includes two parallel conductive paths defining there between a sample zone within the system. A generating unit generates time varying electrical signals which are inserted into one of the two parallel conductive paths. A time domain reflectometer receives the time varying electrical signals returned by the second of the two parallel conductive paths and, responsive thereto, outputs a curve of impedance versus distance. An analysis unit then calculates the area under the curve, subtracts the calculated area from an area produced when the sample zone consists entirely of material of a first fluid phase, and divides this calculated difference by the difference between an area produced when the sample zone consists entirely of material of the first fluid phase and an area produced when the sample zone consists entirely of material of a second fluid phase. The result is the volume fraction.
Laser-induced incandescence: Towards quantitative soot volume fraction measurements
Energy Technology Data Exchange (ETDEWEB)
Tzannis, A.P.; Wienbeucker, F.; Beaud, P.; Frey, H.-M.; Gerber, T.; Mischler, B.; Radi, P.P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1999-08-01
Laser-Induced Incandescence has recently emerged as a versatile tool for measuring soot volume fraction in a wide range of combustion systems. In this work we investigate the essential features of the method. LII is based on the acquisition of the incandescence of soot when heated through a high power laser pulse. Initial experiments have been performed on a model laboratory flame. The behaviour of the LII signal is studied experimentally. By applying numerical calculations we investigate the possibility to obtain two-dimensional soot volume fraction distributions. For this purpose a combination of LII with other techniques is required. This part is discussed in some extent and the future work is outlined. (author) 4 figs., 3 refs.
Effect of reinforcement volume fraction on the density & elastic ...
African Journals Online (AJOL)
unidirectional Zr41.2Ti13.8Cu12.5Ni10Be22.5, Vit.1, Bulk metallic glass matrix composites, reinforced with glass E,. Fe, Mo, Ni, Cr, Mn, Nb, Cd, Pt, U, Cu or Zr fibers, has been investigated. It was found the elastic moduli of high volume fraction composites are improved with the introduction of certain materials reinforcement ...
Extracellular volume fraction in coronary chronic total occlusion patients.
Chen, Yin Yin; Zhang, Wei Guo; Yang, Shan; Yun, Hong; Deng, Sheng Ming; Fu, Cai Xia; Zeng, Meng Su; Jin, Hang; Guo, Liang
2015-08-01
(1) To assess extracellular volume fraction (ECV) and regional systolic function in patients presenting with coronary chronic total occlusion (CTO) in areas without significant late gadolinium enhancement (LGE), and (2) to investigate the correlation between angiography collateral flow and ECV in territories supplied by CTO vessels. A total of 50 angiographically documented CTO patients and 15 age- and sex-matched normal controls were recruited to the study. Myocardial ECV, was calculated in infarcted, global non-infarcted and the entire myocardium respectively. Segmental ECV was calculated from myocardial segments within the perfusion territory of a CTO vessel. The global and regional systolic function was evaluated using ejection fraction and percent systolic thickening. ECVs in global myocardium and global non-infarcted myocardium were significantly elevated in comparison with that in controls (29.1 ± 4.2% and 26.6 ± 2.6% vs. 23.3 ± 2.0%, all P ECV significantly correlated with LV ejection fraction (r = -0.56, P ECV inversely correlated with systolic thickening in global non-infarcted myocardium (r = -0.31, P ECV was associated with the presence of well-developed collaterals (P = 0.004), and multivariate binary logistic analysis demonstrated that mean segmental ECV and course of disease were the independent discriminator of collateral flow with overall diagnostic accuracy of 74.4%. In patients with CTO, ECV is found to be increased beyond that observed with LGE, and correlates with LV regional wall motion abnormality, which appears to reflect diffuse myocardial fibrosis. Mean segmental ECV value, combined with course of disease, may serve as good predictors of collateral flow.
Accuracy of cancellous bone volume fraction measured by micro-CT scanning
DEFF Research Database (Denmark)
Ding, Ming; Odgaard, A; Hvid, I
1999-01-01
which covered a large range of volume fraction (9.8-39.8%) were produced. The specimens were micro-CT scanned, and the volume fraction based on Archimedes' principle was determined as a reference. After scanning, all micro-CT data were segmented using individual thresholds determined by the scanner...
Conklin, Lindsey
2017-01-01
Fiber-reinforced composite structures have become more common in aerospace components due to their light weight and structural efficiency. In general, the strength and stiffness of a composite structure are directly related to the fiber volume fraction, which is defined as the fraction of fiber volume to total volume of the composite. The most common method to measure the fiber volume fraction is acid digestion, which is a useful method when the total weight of the composite, the fiber weight, and the total weight can easily be obtained. However, acid digestion is a destructive test, so the material will no longer be available for additional characterization. Acid digestion can also be difficult to machine out specific components of a composite structure with complex geometries. These disadvantages of acid digestion led the author to develop a method to calculate the fiber volume fraction. The developed method uses optical microscopy to calculate the fiber area fraction based on images of the cross section of the composite. The fiber area fraction and fiber volume fraction are understood to be the same, based on the assumption that the shape and size of the fibers are consistent in the depth of the composite. This tutorial explains the developed method for optically determining fiber area fraction performed at NASA Langley Research Center.
Nakamori, Shiro; Dohi, Kaoru; Ishida, Masaki; Goto, Yoshitaka; Imanaka-Yoshida, Kyoko; Omori, Taku; Goto, Itaru; Kumagai, Naoto; Fujimoto, Naoki; Ichikawa, Yasutaka; Kitagawa, Kakuya; Yamada, Norikazu; Sakuma, Hajime; Ito, Masaaki
2017-06-09
The purpose of this study was to examine the histological correlation of native myocardial T1 and extracellular volume fraction (ECV) measurement at 3-T for the assessment of diffuse pathological changes in the myocardial tissue, including myocardial fibrosis and extracellular space in dilated cardiomyopathy (DCM). Cardiac magnetic resonance T1 techniques allow the quantification of diffuse myocardial fibrosis. However, there are no definitive head-to-head studies of native T1 versus ECV for the detection, quantification, and characterization of pathological changes in the myocardial tissue in DCM by using histological samples for confirmation. A total of 36 subjects with DCM (31 men, mean age 56 ± 16 years) underwent pre- and post-contrast T1 mapping as well as late gadolinium enhancement (LGE) cardiac magnetic resonance at 3-T. Biopsy samples were used for the quantification of collagen volume fraction using picrosirius red staining and an extracellular space component from hematoxylin and eosin-stained myocardium. Nonischemic LGE was observed in 14 of 36 patients. Although patients with LGE had significantly greater biopsy-proven collagen volume fraction than those without LGE (21 ± 12% vs. 11 ± 8%; p T1 value and ECV were similarly and significantly associated with biopsy-proven collagen volume fraction (r = 0.77 and r = 0.66, respectively; p T1 had only a moderate correlation (r = 0.55). Interobserver and intraobserver reproducibility for native T1 and ECV were 0.89, 0.95, 0.96, and 0.98, respectively. Native T1 exhibited comparable ability as ECV measurement in the detection and quantification of histological collagen volume fraction, with high reproducibility, and therefore diffuse myocardial fibrosis in DCM may be reliably assessed by native T1 mapping without the administration of gadolinium contrast agent. In addition, cardiac magnetic resonance-derived ECV showed excellent agreement with histological extracellular space. Copyright © 2017
Lamb Waves in a Functionally Graded Composite Plate with Nonintegral Power Function Volume Fractions
National Research Council Canada - National Science Library
Cao, Xiaoshan; Qu, Zhen; Shi, Junping; Ru, Yan
2015-01-01
...) plate, which is a composite of two kinds of materials. The mechanical parameters depend on the volume fractions, which are nonintegral power functions, and the gradient coefficient is the power value...
Volumic omit maps in ab initio dual-space phasing.
Oszlányi, Gábor; Sütő, András
2016-07-01
Alternating-projection-type dual-space algorithms have a clear construction, but are susceptible to stagnation and, thus, inefficient for solving the phase problem ab initio. To improve this behaviour new omit maps are introduced, which are real-space perturbations applied periodically during the iteration process. The omit maps are called volumic, because they delete some predetermined subvolume of the unit cell without searching for atomic regions or analysing the electron density in any other way. The basic algorithms of positivity, histogram matching and low-density elimination are tested by their solution statistics. It is concluded that, while all these algorithms based on weak constraints are practically useless in their pure forms, appropriate volumic omit maps can transform them to practically useful methods. In addition, the efficiency of the already useful reflector-type charge-flipping algorithm can be further improved. It is important that these results are obtained by using non-sharpened structure factors and without any weighting scheme or reciprocal-space perturbation. The mathematical background of volumic omit maps and their expected applications are also discussed.
Matos, B. R.; Isidoro, R. A.; Santiago, E. I.; Fonseca, F. C.
2014-12-01
The present study reports on the performance enhancement of direct ethanol fuel cell (DEFC) at 130 °C with Nafion-titania composite electrolytes prepared by sol-gel technique and containing high volume fractions of the ceramic phase. It is found that for high volume fractions of titania (>10 vol%) the ethanol uptake of composites is largely reduced while the proton conductivity at high-temperatures is weakly dependent on the titania content. Such tradeoff between alcohol uptake and conductivity resulted in a boost of DEFC performance at high temperatures using Nafion-titania composites with high fraction of the inorganic phase.
Viscosity of water-in-oil emulsions. Variation with temperature and water volume fraction
Energy Technology Data Exchange (ETDEWEB)
Farah, Marco A.; Caldas, Jorge Navaes [Petroleo Brasileiro S.A., Rua General Canabarro, 500, Maracana, Rio, CEP 2057-900 (Brazil); Oliveira, Roberto C. [Petroleo Brasileiro S.A., Cenpes, Cidade Universitaria (Brazil); Rajagopal, Krishnaswamy [LATCA-Laboratorio de Termodinamica e Cinetica Aplicada-Escola de Quimica, Departamento de Engenharia Quimica, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universitaria, C.P. 68452, CEP 21949-900, Rio de Janeiro (Brazil)
2005-09-15
Water-in-oil emulsions are important in the petroleum industry in production operations, where the water content of the emulsion can be as high as 60% in volume, also in petroleum refining operations where generally the water content is low. The effective viscosity of water-in-oil emulsions depends mainly on the volume fraction of dispersed phase and temperature, along with several minor effects, such as shear rate, average droplet size, droplet size distribution, viscosity and density of oil. Using six different crude oils, the effective viscosities of several synthetic water-in-oil emulsions are measured at atmospheric pressure using a dynamic viscosimeter for different shear rates, temperatures and volume fractions of the dispersed phase. The ASTM equation, method D-341, for describing viscosity as a function of temperature is extended to include the variation of dispersed phase volume fraction. The proposed equation gives good correlation between the measured viscosities of water-in-oil emulsions as a function of temperature and the volume fraction of water.
Ezzati, Ali; Katz, Mindy J; Lipton, Michael L; Zimmerman, Molly E; Lipton, Richard B
2016-09-01
The objective of this study was to investigate the relationship of medial temporal lobe and posterior cingulate cortex (PCC) volumetrics as well as fractional anisotropy of the cingulum angular bundle (CAB) and the cingulum cingulate gyrus (CCG) bundle to performance on measures of verbal memory in non-demented older adults. The participants were 100 non-demented adults over the age of 70 years from the Einstein Aging Study. Volumetric data were estimated from T1-weighted images. The entire cingulum was reconstructed using diffusion tensor MRI and probabilistic tractography. Association between verbal episodic memory and MRI measures including volume of hippocampus (HIP), entorhinal cortex (ERC), PCC and fractional anisotropy of CAB and CCG bundle were modeled using linear regression. Relationships between atrophy of these structures and regional cingulum fractional anisotropy were also explored. Decreased HIP volume on the left and decreased fractional anisotropy of left CAB were associated with lower memory performance. Volume changes in ERC, PCC and CCG disruption were not associated with memory performance. In regression models, left HIP volume and left CAB-FA were each independently associated with episodic memory. The results suggest that microstructural changes in the left CAB and decreased left HIP volume independently influence episodic memory performance in older adults without dementia. The importance of these findings in age and illness-related memory decline require additional exploration.
Energy Technology Data Exchange (ETDEWEB)
Mercier, J.C.; DiSessa, T.G.; Jarmakani, J.M.; Nakanishi, T.; Hiraishi, S.; Isabel-Jones, J.; Friedman, W.F.
1982-05-01
The ability of two-dimensional echocardiography to measure left ventricular volumes and ejection fraction was evaluated in 25 children with congenital heart disease. Dimensions and planimetered areas were obtained in the short-axis view at the mitral valve and high and low papillary muscle levels and in the apical two- and four-chamber views. Eight algorithms using five geometric models were assessed. Left ventricular end-diastolic volume, end-systolic volume and ejection fraction were compared with data from biplane cineangiocardiograms. The correlation varied with the algorithm used. Algorithms using short-axis views appeared superior to those using only apical long-axis views. Four algorithms estimated left ventricular volumes with equal accuracy (Simpson's rule, assuming the ventricle to be a truncated cone; Simpson's rule, algorithm that best estimated left ventricular ejection fraction was the ellipsoid biplane formula using the short-axis view at the papillary muscle level (r = 0.91, slope = 0.94, SEE = 6.7%). Thus, two-dimensional echocardiography can accurately assess left ventricular volumes and ejection fraction in children with congenital heart disease.
Phase-segregated model for plant cell culture: The effect of cell volume fraction
Energy Technology Data Exchange (ETDEWEB)
Zhang, W. [Univ. of Adelaide, Adelaide (Australia). Dept. of Chemical Engineering]|[Tokyo Univ. (Japan)hinese Academy of Sciences, Dalian (China). Dalian Inst. of Chemical Physics; Furusaki, S. [Tokyo Univ. (Japan)] Middelberg, A. [Univ. of Adelaide, Adelaide (Australia). Dept. of Chemical Engineering
1998-06-01
Plant cells are characterized by low water content, so the fraction of cell volume (volume fraction) in a vessel is large compared with other cell systems, even if the cell concentrations are the same. Therefore, concentration of plant cells should preferably be expressed by the liquid volume basis rather than by the total vessel volume basis. In this paper, a new model is proposed to analyze behavior of a plant cell culture by dividing the cell suspension into the biotic- and abiotic-phases. Using this model, we analyzed the cell-growth and the alkaloid production by Catharanthus roseus. Large errors in the simulated results were observed if the phase-segregation was not considered. 12 refs., 3 figs.
Directory of Open Access Journals (Sweden)
Zhu Chun
2012-12-01
Full Text Available In this paper, Riemann-Liouville type fractional integral identity and inequality for differentiable convex mappings are studied. Some applications to special means of real numbers are given. Finally, error estimates for a midpoint formula are also obtained.
Savannah fractional woody vegetation cover mapping with optical and radar data and machine learning
Symeonakis, Elias; Marqués-Mateu, Ángel; Petroulaki, Kyriaki; Higginbottom, Thomas
2017-04-01
The fraction of woody vegetation plays an important role in natural and anthropogenic processes of savannah ecosystems. We investigate the optimal combination of Landsat optical and thermal bands as well as ALOS PALSAR L-band radar data from both wet and dry seasons for the mapping of fractional woody vegetation cover in southern African savannah environments. We employ colour aerial photography for sampling and validation and a random forest classification approach to map the fraction of woody cover in the Northwest Province of South Africa. Our results from random forests classifications show that the most accurate estimates are produced from the model that incorporates all parameters: Landsat optical and thermal bands and vegetation indices for the dry and wet seasons, and HH and HV polarised ALOS PALSAR L-band data. However, the combination of the six Landsat bands from either the wet or the dry season with either the HH or the HV PALSAR band, appears to be sufficient for achieving fractional woody cover balanced accuracies of >85%. Dry season optical bands alone are able to map fractional woody cover with more than 80% balanced accuracy. Our findings can provide much needed assistance to woody vegetation monitoring efforts in southern African savannahs where its expansion over the last decades is partly attributed to bush encroachment and land degradation brought about by recent climatic changes and/or land mismanagement.
Andrews, C. W.
1976-01-01
Volume fraction of a constituent or phase was estimated in six specimens of conventional and DS-eutectic superalloys, using ASTM E562-76, a new standard recommended practice for determining volume fraction by systematic manual point count. Volume fractions determined ranged from 0.086 to 0.36, and with one exception, the 95 percent relative confidence limits were approximately 10 percent of the determined volume fractions. Since the confidence-limit goal of 10 percent, which had been arbitrarily chosen previously, was achieved in all but one case, this application of the new practice was considered successful.
Pancreas volume and fat fraction in children with Type 1 diabetes.
Regnell, S E; Peterson, P; Trinh, L; Broberg, P; Leander, P; Lernmark, Å; Månsson, S; Elding Larsson, H
2016-10-01
People with Type 1 diabetes have smaller pancreases than healthy individuals. Several diseases causing pancreatic atrophy are associated with pancreatic steatosis, but pancreatic fat in Type 1 diabetes has not been measured. This cross-sectional study aimed to compare pancreas size and fat fraction in children with Type 1 diabetes and controls. The volume and fat fraction of the pancreases of 22 children with Type 1 diabetes and 29 controls were determined using magnetic resonance imaging. Pancreas volume was 27% smaller in children with diabetes (median 34.9 cm(3) ) than in controls (47.8 cm(3) ; P Pancreas volume correlated positively with age in controls (P = 0.033), but not in children with diabetes (P = 0.649). Pancreas volume did not correlate with diabetes duration, but it did correlate positively with units of insulin/kg body weight/day (P = 0.048). A linear model of pancreas volume as influenced by age, body surface area and insulin units/kg body weight/day found that insulin dosage correlated with pancreas volume after controlling for both age and body surface area (P = 0.009). Pancreatic fat fraction was not significantly different between the two groups (1.34% vs. 1.57%; P = 0.891). Our findings do not indicate that pancreatic atrophy in Type 1 diabetes is associated with an increased pancreatic fat fraction, unlike some other diseases featuring reduced pancreatic volume. We speculate that our results may support the hypotheses that much of pancreatic atrophy in Type 1 diabetes occurs before the clinical onset of the disease and that exogenous insulin administration decelerates pancreatic atrophy after diabetes onset. © 2016 Diabetes UK.
Thermosetting resins with high fractions of free volume and inherently low dielectric constants.
Lin, Liang-Kai; Hu, Chien-Chieh; Su, Wen-Chiung; Liu, Ying-Ling
2015-08-18
This work demonstrates a new class of thermosetting resins, based on Meldrum's acid (MA) derivatives, which have high fractions of free volume and inherently low k values of about 2.0 at 1 MHz. Thermal decomposition of the MA groups evolves CO2 and acetone to create air-trapped cavities so as to reduce the dielectric constants.
Non-contact spectroscopic determination of large blood volume fractions in turbid media
R.H. Bremmer (Rolf); S.C. Kanick (Stephen); N. Laan (Nick); A. Amelink (Arjen); T.G. van Leeuwen (Ton); M.J.A.M. Aalders
2011-01-01
textabstractWe report on a non-contact method to quantitatively determine blood volume fractions in turbid media by reflectance spectroscopy in the VIS/NIR spectral wavelength range. This method will be used for spectral analysis of tissue with large absorption coefficients and assist in age
Jamming in frictionless packings of spheres: determination of the critical volume fraction
Göncü, F.; Göncü, F.; Duran Vinent, Orencio; Durán, O.; Masami, Nakagawa; Luding, Stefan
2009-01-01
The jamming transition in granular packings is characterized by a sudden change in the coordination number. In this work we investigate the evolution of coordination number as function of volume fraction for frictionless packings of spheres undergoing isotropic deformation. Using the results
Blood volume fraction imaging of the human lung using intravoxel incoherent motion.
Carinci, Flavio; Meyer, Cord; Phys, Dipl; Breuer, Felix A; Triphan, Simon; Choli, Morwan; Phys, Dipl; Jakob, Peter M
2015-05-01
To present a technique for non-contrast-enhanced in vivo imaging of the blood volume fraction of the human lung. The technique is based on the intravoxel incoherent motion (IVIM) approach. However, a substantial novelty is introduced here: the need for external diffusion sensitizing gradients is eliminated by exploiting the internal magnetic field gradients typical of the lung tissue, due to magnetic susceptibility differences at air/tissue interfaces. A single shot turbo spin-echo sequence with stimulated-echo preparation and electrocardiograph synchronization was used for acquisition. Two images were acquired in a single breath-hold of 10 seconds duration: one reference image and one blood-suppressed image. The blood volume fraction was quantified using a two-compartment signal decay model, as given by the IVIM theory. Experiments were performed at 1.5T in eight healthy volunteers. Values of the blood volume fraction obtained within the lung parenchyma (36 ± 16%) are in good agreement with previous reports, obtained using contrast-enhanced magnetic resonance angiography (33%), and show relatively good reproducibility. The presented technique offers a robust way to quantify the blood volume fraction of the human lung parenchyma without using contrast agents. Image acquisition can be accomplished in a single breath-hold and could be suitable for clinical applications on patients with lung diseases. J. Magn. Reson. Imaging 2015;41:1454-1464. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.
A novel optical method for estimating the near-wall volume fraction in granular flows
Sarno, Luca; Nicolina Papa, Maria; Carleo, Luigi; Tai, Yih-Chin
2016-04-01
Geophysical phenomena, such as debris flows, pyroclastic flows and rock avalanches, involve the rapid flow of granular mixtures. Today the dynamics of these flows is far from being deeply understood, due to their huge complexity compared to clear water or monophasic fluids. To this regard, physical models at laboratory scale represent important tools for understanding the still unclear properties of granular flows and their constitutive laws, under simplified experimental conditions. Beside the velocity and the shear rate, the volume fraction is also strongly interlinked with the rheology of granular materials. Yet, a reliable estimation of this quantity is not easy through non-invasive techniques. In this work a novel cost-effective optical method for estimating the near-wall volume fraction is presented and, then, applied to a laboratory study on steady-state granular flows. A preliminary numerical investigation, through Monte-Carlo generations of grain distributions under controlled illumination conditions, allowed to find the stochastic relationship between the near-wall volume fraction, c3D, and a measurable quantity (the two-dimensional volume fraction), c2D, obtainable through an appropriate binarization of gray-scale images captured by a camera placed in front of the transparent boundary. Such a relation can be well described by c3D = aexp(bc2D), with parameters only depending on the angle of incidence of light, ζ. An experimental validation of the proposed approach is carried out on dispersions of white plastic grains, immersed in various ambient fluids. The mixture, confined in a box with a transparent window, is illuminated by a flickering-free LED lamp, placed so as to form a given ζ with the measuring surface, and is photographed by a camera, placed in front of the same window. The predicted exponential law is found to be in sound agreement with experiments for a wide range of ζ (10° digital scale at the channel outlet for measuring the mass flow
Mapping soil textural fractions across a large watershed in north-east Florida.
Lamsal, S; Mishra, U
2010-08-01
Assessment of regional scale soil spatial variation and mapping their distribution is constrained by sparse data which are collected using field surveys that are labor intensive and cost prohibitive. We explored geostatistical (ordinary kriging-OK), regression (Regression Tree-RT), and hybrid methods (RT plus residual Sequential Gaussian Simulation-SGS) to map soil textural fractions across the Santa Fe River Watershed (3585 km(2)) in north-east Florida. Soil samples collected from four depths (L1: 0-30 cm, L2: 30-60 cm, L3: 60-120 cm, and L4: 120-180 cm) at 141 locations were analyzed for soil textural fractions (sand, silt and clay contents), and combined with textural data (15 profiles) assembled under the Florida Soil Characterization program. Textural fractions in L1 and L2 were autocorrelated, and spatially mapped across the watershed. OK performance was poor, which may be attributed to the sparse sampling. RT model structure varied among textural fractions, and the model explained variations ranged from 25% for L1 silt to 61% for L2 clay content. Regression residuals were simulated using SGS, and the average of simulated residuals were used to approximate regression residual distribution map, which were added to regression trend maps. Independent validation of the prediction maps showed that regression models performed slightly better than OK, and regression combined with average of simulated regression residuals improved predictions beyond the regression model. Sand content >90% in both 0-30 and 30-60 cm covered 80.6% of the watershed area. Copyright 2010 Elsevier Ltd. All rights reserved.
Parallel plate model for trabecular bone exhibits volume fraction-dependant bias
DEFF Research Database (Denmark)
Day, J; Ding, Ming; Odgaard, A
2000-01-01
, canine distal femur, rat tail, and pig spine and scanned in a micro-CT scanner. Trabecular thickness, trabecular spacing, and trabecular number were calculated using the parallel plate model. Direct thickness, and spacing and connectivity density were calculated using unbiased three-dimensional methods....... Both thickness and spacing calculated using the plate model were well correlated to the direct three-dimensional measures (r(2) = 0. 77-0.92). The correlation between trabecular number and connectivity density varied greatly (r(2) = 0.41-0.94). Whereas trabecular thickness was consistently...... underestimated using the plate model, trabecular spacing was underestimated at low volume fractions and overestimated at high volume fractions. Use of the plate model resulted in a volume-dependent bias in measures of thickness and spacing (p
Collins, Jeremy; Sommerville, Cort; Magrath, Patrick; Spottiswoode, Bruce; Freed, Benjamin H; Benzuly, Keith H; Gordon, Robert; Vidula, Himabindu; Lee, Dan C; Yancy, Clyde; Carr, James; Markl, Michael
2014-01-01
Background Non-ischemic cardiomyopathy (NICM) is a common cause of left ventricular (LV) dysfunction and myocardial fibrosis. The purpose of this study was to non-invasively evaluate changes in segmental LV extracellular volume fraction (ECV), LV velocities, myocardial scar, and wall motion in NICM patients. Methods and Results Cardiac MRI including pre- and post-contrast myocardial T1-mapping and velocity quantification (tissue phase mapping, TPM) of the LV (basal, mid-ventricular, apical short axis) was applied in 31 patients with NICM (50±18years). Analysis based on the 16-segment AHA model was employed to evaluate the segmental distribution of ECV, peak systolic and diastolic myocardial velocities, scar determined by late gadolinium enhancement (LGE), and wall motion abnormalities. LV segments with scar or impaired wall motion were significantly associated with elevated ECV (r=0.26, pECV were similar for patients with reduced (n=12, ECV=0.28±0.06) and preserved LV ejection fraction (LVEF) (n=19, ECV=0.30±0.09). Patients with preserved LVEF showed significant relationships between increasing ECV and reduced systolic (r=−0.19, r=−0.30) and diastolic (r=0.34, r=0.26) radial and long-axis peak velocities (pECV and segmental LV velocities were maintained indicating the potential of elevated ECV to identify regional diffuse fibrosis not visible by LGE which was associated with impaired regional LV function Conclusions Regionally elevated ECV negatively impacted myocardial velocities. The association of elevated regional ECV with reduced myocardial velocities independent of LVEF suggests a structure-function relationship between altered ECV and segmental myocardial function in NICM. PMID:25552491
White, Steven K; Sado, Daniel M; Fontana, Marianna; Banypersad, Sanjay M; Maestrini, Viviana; Flett, Andrew S; Piechnik, Stefan K; Robson, Matthew D; Hausenloy, Derek J; Sheikh, Amir M; Hawkins, Philip N; Moon, James C
2013-09-01
The aim of this study was to determine the accuracy of the contrast "bolus only" T1 mapping cardiac magnetic resonance (CMR) technique for measuring myocardial extracellular volume fraction (ECV). Myocardial ECV can be measured with T1 mapping before and after contrast agent if the contrast agent distribution between blood/myocardium is at equilibrium. Equilibrium distribution can be achieved with a primed contrast infusion (equilibrium contrast-CMR [EQ-CMR]) or might be approximated by the dynamic equilibration achieved by delayed post-bolus measurement. This bolus only approach is highly attractive, but currently limited data support its use. We compared the bolus only technique with 2 independent standards: collagen volume fraction (CVF) from myocardial biopsy in aortic stenosis (AS); and the infusion technique in 5 representative conditions. One hundred forty-seven subjects were studied: healthy volunteers (n = 50); hypertrophic cardiomyopathy (n = 25); severe AS (n = 22); amyloid (n = 20); and chronic myocardial infarction (n = 30). Bolus only (at 15 min) and infusion ECV measurements were performed and compared. In 18 subjects with severe AS the results were compared with histological CVF. The ECV by both techniques correlated with histological CVF (n = 18, r² = 0.69, p infarction), Bland-Altman analysis indicates the bolus only technique has a consistent and increasing offset, giving a higher value for ECVs above 0.4 (mean difference ± limit of agreement for ECV 0.4 = 0.040 ± 0.075, p T1 mapping-derived ECV measurement is sufficient for ECV measurement across a range of cardiac diseases, and this approach is histologically validated in AS. However, when ECV is >0.4, the bolus only technique consistently measures ECV higher compared with infusion. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Determination of volume fractions in two-phase flows from sound speed measurement
Energy Technology Data Exchange (ETDEWEB)
Chaudhuri, Anirban [Los Alamos National Laboratory; Sinha, Dipen N. [Los Alamos National Laboratory; Osterhoudt, Curtis F. [University of Alaska
2012-08-15
Accurate measurement of the composition of oil-water emulsions within the process environment is a challenging problem in the oil industry. Ultrasonic techniques are promising because they are non-invasive and can penetrate optically opaque mixtures. This paper presents a method of determining the volume fractions of two immiscible fluids in a homogenized two-phase flow by measuring the speed of sound through the composite fluid along with the instantaneous temperature. Two separate algorithms are developed by representing the composite density as (i) a linear combination of the two densities, and (ii) a non-linear fractional formulation. Both methods lead to a quadratic equation with temperature dependent coefficients, the root of which yields the volume fraction. The densities and sound speeds are calibrated at various temperatures for each fluid component, and the fitted polynomial is used in the final algorithm. We present results when the new algorithm is applied to mixtures of crude oil and process water from two different oil fields, and a comparison of our results with a Coriolis meter; the difference between mean values is less than 1%. Analytical and numerical studies of sensitivity of the calculated volume fraction to temperature changes and calibration errors are also presented.
Niinemets, Ulo; Lukjanova, Aljona; Turnbull, Matthew H; Sparrow, Ashley D
2007-08-01
Acclimation potential of needle photosynthetic capacity varies greatly among pine species, but the underlying chemical, anatomical and morphological controls are not entirely understood. We investigated the light-dependent variation in needle characteristics in individuals of Pinus patula Schlect. & Cham., which has 19-31-cm long pendulous needles, and individuals of P. radiata D. Don., which has shorter (8-17-cm-long) stiffer needles. Needle nitrogen and carbon contents, mesophyll and structural tissue volume fractions, needle dry mass per unit total area (M(A)) and its components, volume to total area ratio (V/A(T)) and needle density (D = M(A)/(V/A(T))), and maximum carboxylase activity of Rubisco (V(cmax)) and capacity of photosynthetic electron transport (J(max)) were investigated in relation to seasonal mean integrated irradiance (Q(int)). Increases in Q(int) from canopy bottom to top resulted in proportional increases in both needle thickness and width such that needle total to projected surface area ratio, characterizing the efficiency of light interception, was independent of Q(int). Increased light availability also led to larger M(A) and nitrogen content per unit area (N(A)). Light-dependent modifications in M(A) resulted from increases in both V/A(T) and D, whereas N(A) changed because of increases in both M(A) and mass-based nitrogen content (N(M)) (N(A) = N(M)M(A)). Overall, the volume fraction of mesophyll cells increased with increasing irradiance and V/A(T) as the fraction of hypodermis and epidermis decreased with increasing needle thickness. Increases in M(A) and N(A) resulted in enhanced J(max) and V(cmax) per unit area in both species, but mass-based photosynthetic capacity increased only in P. patula. In addition, J(max) and V(cmax) showed greater plasticity in response to light in P. patula. Species differences in mesophyll volume fraction explained most of the variation in mass-based needle photosynthetic capacity between species
Quantitative susceptibility mapping of small objects using volume constraints.
Liu, Saifeng; Neelavalli, Jaladhar; Cheng, Yu-Chung N; Tang, Jin; Mark Haacke, E
2013-03-01
Microbleeds have been implicated to play a role in many neurovascular and neurodegenerative diseases. The diameter of each microbleed has been used previously as a possible quantitative measure for grading microbleeds. We propose that magnetic susceptibility provides a new quantitative measure of extravasated blood. Recently, a Fourier-based method has been used that allows susceptibility quantification from phase images for any arbitrarily shaped structures. However, when very small objects, such as microbleeds, are considered, the accuracy of this susceptibility mapping method still remains to be evaluated. In this article, air bubbles and glass beads are taken as microbleed surrogates to evaluate the quantitative accuracy of the susceptibility mapping method. We show that when an object occupies only a few voxels, an estimate of the true volume of the object is necessary for accurate susceptibility quantification. Remnant errors in the quantified susceptibilities and their sources are evaluated. We show that quantifying magnetic moment, rather than the susceptibility of these small structures, may be a better and more robust alternative. Copyright © 2012 Wiley Periodicals, Inc.
Na, Kyung-Su; Kim, Ji-Hwan
2008-02-01
The volume fraction optimization of Functionally Graded Material (FGM) composite plate is investigated for stress reduction and thermo-mechanical buckling. Material properties are assumed to be temperature dependent and varied continuously in the thickness direction. The 3-D finite element is adopted using an 18-node solid element to analyze the plate model more accurately for the variation of material properties and temperature field in the thickness direction. Tensile and compressive stress ratios of the structure under mechanical load are evaluated for stress analysis. Temperature at each node is obtained by solving the steady-state heat transfer problem in the thermo-mechanical buckling analysis, and Newton-Raphson method is used for nonlinear analysis. Tensile stress ratios, compressive stress ratios and critical temperatures are analyzed for various thickness ratios and volume fraction distributions in the numerical study. Finally, the optimal design of FGM composite plate is investigated by considering the stress and the critical temperature.
Rheology of suspensions of viscoelastic spheres: Deformability as an effective volume fraction
Rosti, Marco E.; Brandt, Luca; Mitra, Dhrubaditya
2018-01-01
We study suspensions of deformable (viscoelastic) spheres in a Newtonian solvent in plane Couette geometry, by means of direct numerical simulations. We find that in the limit of vanishing inertia, the effective viscosity μ of the suspension increases as the volume fraction occupied by the spheres Φ increases and decreases as the elastic modulus of the spheres G decreases; the function μ (Φ ,G ) collapses to a universal function μ (Φe) with a reduced effective volume fraction Φe(Φ ,G ) . Remarkably, the function μ (Φe) is the well-known Eilers fit that describes the rheology of suspension of rigid spheres at all Φ . Our results suggest different ways to interpret the macrorheology of blood.
Wang, Ya-fei; Huang, Qun-xing; Wang, Fei; Chi, Yong; Yan, Jian-hua
2018-01-01
A novel method to evaluate the quantitative effects of soot morphology and incident wavelength on the measurement accuracy of soot volume fraction, by the laser extinction (LE) technique is proposed in this paper. The results indicate that the traditional LE technique would overestimate soot volume fraction if the effects of morphology and wavelength are not considered. Before the agglomeration of isolated soot primary particles, the overestimation of the LE technique is in the range of 2–20%, and rises with increasing primary particle diameter and with decreasing incident wavelength. When isolated primary particles are agglomerated into fractal soot aggregates, the overestimation would exceed 30%, and rise with increasing primary particle number per soot aggregate, fractal dimension and fractal prefactor and with decreasing incident wavelength to a maximum value of 55%. Finally, based on these results above, the existing formula of the LE technique gets modified, and the modification factor is 0.65–0.77.
The equivalent electrical permittivity of gas-solid mixtures at intermediate solid volume fractions.
Energy Technology Data Exchange (ETDEWEB)
Torczynski, John Robert; Ceccio, Steven Louis; Tortora, Paul Richard
2005-07-01
Several mixture models are evaluated for their suitability in predicting the equivalent permittivity of dielectric particles in a dielectric medium for intermediate solid volume fractions (0.4 to 0.6). Predictions of the Maxwell, Rayleigh, Bottcher and Bruggeman models are compared to computational simulations of several arrangements of solid particles in a gas and to the experimentally determined permittivity of a static particle bed. The experiment uses spherical glass beads in air, so air and glass permittivity values (1 and 7, respectively) are used with all of the models and simulations. The experimental system used to measure the permittivity of the static particle bed and its calibration are described. The Rayleigh model is found to be suitable for predicting permittivity over the entire range of solid volume fractions (0-0.6).
Energy Technology Data Exchange (ETDEWEB)
Salgado, C.M.; Pereira, Claudio M.N.A.; Brandao, Luis E.B., E-mail: otero@ien.gov.b, E-mail: cmnap@ien.gov.b, E-mail: brandao@ien.gov.b [Instituto de Engenharia Nuclear (DIRA/IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Radiofarmacos
2011-07-01
This work investigates the response of a volume fraction prediction system for water-gas-oil multiphase flows considering variations on water salinity. The approach is based on gamma-ray pulse height distributions pattern recognition by means the artificial neural networks (ANNs). The detection system uses appropriate fan beam geometry, comprised of a dual-energy gamma-ray source and two NaI(Tl) detectors adequately positioned outside the pipe in order measure transmitted and scattered beams. An ideal and static theoretical model for annular flow regime have been developed using MCNP-X code, which was used to provide training, test and validation data for the ANN. More than 500 simulations have been done, in which water salinity have been ranged from 0 to 16% in order to cover a most practical situations. Validation tests have included values of volume fractions and water salinity different from those used in ANN training phase. The results presented here show that the proposed approach may be successfully applied to material volume fraction prediction on watergas- oil multiphase flows considering practical (real) levels of variations in water salinity. (author)
Energy Technology Data Exchange (ETDEWEB)
Brown, Judith Alice [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Long, Kevin Nicholas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-05-01
This work was done to support customer questions about whether a Sylgard/Glass Microballoon (GMB) potting material in current use could be replaced with pure Sylgard and if this would significantly change stresses imparted to internal components under thermal cycling conditions. To address these questions, we provide micromechanics analysis of Sylgard/GMB materials using both analytic composite theory and finite element simulations to better understand the role of the GMB volume fraction in determining thermal expansion coefficient, elastic constants, and behavior in both confined and unconfined compression boundary value problems. A key finding is that damage accumulation in the material from breakage of GMBs significantly limits the global stress magnitude and results in a plateau stress behavior over large ranges of compressive strain. The magnitude of this plateau stress is reduced with higher volume fractions of GMBs. This effect is particularly pronounced in confined compression, which we estimate bears the most similarity to the application of interest. This stress-limiting damage mechanism is not present in pure Sylgard, however, and the result is much higher stresses under confined compression. Thus, we recommend that some volume fraction greater than 10% GMBs be used for confined deformation applications.
Kellman, Peter; Arai, Andrew E; Xue, Hui
2013-06-21
Quantitative measurements in the myocardium may be used to detect both focal and diffuse disease processes that result in an elevation of T1 and/or extracellular volume (ECV) fraction. Detection of abnormal myocardial tissue by these methods is affected by both the accuracy and precision. The sensitivity for detecting abnormal elevation of T1 and ECV is limited by the precision of T1 estimates which is a function of the number and timing of measurements along the T1-inversion recovery curve, the signal-to-noise ratio (SNR), the tissue T1, and the method of fitting. The standard deviation (SD) of T1 and ECV estimates are formulated and SD maps are calculated on a pixel-wise basis using the Modified Look-Locker Inversion recovery (MOLLI) method. SD estimates are validated by numerical simulation using Monte-Carlo analysis and with phantoms using repeated trials. SD estimates are provided for pre- and post-contrast optimized protocols for a range of T1s and SNRs. In-vivo examples are provide for normal, myocarditis, and HCM in human subjects. The formulation of SD maps was extended to R1 and ECV. The measured myocardial SNR ranged from 23 to 43 across the heart using the specific T1-mapping protocol in this study. In this range of SNRs, the estimated SD for T1 was approximately 20-45 ms for pre-contrast myocardial T1 around 1000 ms, and was approximately 10-20 ms for post contrast T1 around 400 ms. The proposed estimate of SD was an unbiased estimate of the standard deviation of T1 validated by numerical simulation and had > 99% correlation with phantom measurements. The measured SD maps exhibited variation across the heart due to drop off in surface coil sensitivity as expected for the variation in SNR. Focal elevation in T1 and ECV was shown to have statistical significance on a pixel-wise basis for in-vivo examples. Pixel-wise estimates of T1 mapping errors have been formulated and validated, and the formulation has been extended to ECV. The ability to
Fractional Snow Cover Mapping by Artificial Neural Networks and Support Vector Machines
Çiftçi, B. B.; Kuter, S.; Akyürek, Z.; Weber, G.-W.
2017-11-01
Snow is an important land cover whose distribution over space and time plays a significant role in various environmental processes. Hence, snow cover mapping with high accuracy is necessary to have a real understanding for present and future climate, water cycle, and ecological changes. This study aims to investigate and compare the design and use of artificial neural networks (ANNs) and support vector machines (SVMs) algorithms for fractional snow cover (FSC) mapping from satellite data. ANN and SVM models with different model building settings are trained by using Moderate Resolution Imaging Spectroradiometer surface reflectance values of bands 1-7, normalized difference snow index and normalized difference vegetation index as predictor variables. Reference FSC maps are generated from higher spatial resolution Landsat ETM+ binary snow cover maps. Results on the independent test data set indicate that the developed ANN model with hyperbolic tangent transfer function in the output layer and the SVM model with radial basis function kernel produce high FSC mapping accuracies with the corresponding values of R = 0.93 and R = 0.92, respectively.
Validation of Binary, Fractional and Interpolated Snow Maps at Multiple Resolutions
Rittger, K.; McKenzie, C.; Painter, T.; Dozier, J.
2008-12-01
Mapping snow cover from multispectral sensors began with a simple normalized index using visible and near infrared wavelengths to classify pixels as either snow covered or snow free, a "binary" classification. Using a canopy reflectance model and incorporating a vegetation index improved the binary algorithm. Although the binary snow mapping methods are computationally simple, they are in practice flawed because sensors with fine spatial resolution usually have a coarse temporal resolution, and vice versa. For sensors with fine enough temporal resolution to track the dynamic seasonal snow environment, few pixels are either completely snow covered or completely snow free. Methods to estimate snow cover enable us to determine the fraction of the pixel covered with snow. Fractional methods include: decision tree classifiers, relationships of snow cover to snow index developed using regressions with finer-resolution data, and spectral un-mixing. Finally, daily data can be interpolated to produce a best estimate of snow cover. Here, we compare snow cover retrievals from binary and fractional snow cover algorithms using various satellites at fine and moderate resolution: AVHRR (1km), MODIS (500m), Landsat (30m) and ASTER (15m), AVIRIS (2m), and 1m data from degraded classified imagery. For binary snow cover we use both NDSI and NDSI with vegetation correction. For fractional snow cover we use a currently implemented operation algorithm MOD10A1 and our own estimates from MODSCAG spectral un-mixing. For smoothed estimates of snow cover we use another operational algorithm, MOD10A2 and our own reanalysis of MODSCAG fractional snow cover. The main study area is the Sierra Nevada of California, along with scenes in the Upper Rio Grande, Colorado Rocky Mountains and the Annapurna and Khumbal Himal. We find that fractional methods are superior to binary methods. Moreover, we find that linear spectral un-mixing gives the best estimates of snow cover at moderate resolution over
Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead
Yang, Sha; Liu, Yun
2015-01-01
The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac’s formalism of full-electron wave function. Equilibrium 202Hg/198Hg, 205Tl/203Tl, 207Pb/206Pb and 208Pb/206Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of vs. for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb4+-bearing species are found can enrich heavier Pb isotopes than Pb2+-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of 208Pb/206Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb2+-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., ) and odd-mass MIFs (i.e., ) are almost the same but with opposite signs. PMID:26224248
Statistics of the fractional polarization of compact radio sources in Planck maps
Bonavera, Laura; González-Nuevo, Joaquin; Argüeso, Francisco; Toffolatti, Luigi
2017-08-01
In this work, we apply the stacking technique to estimate the average fractional polarization from 30 to 353 GHz of a primary sample of 1560 compact sources - essentially all radio sources - detected in the 30 GHz Planck all-sky map and listed in the second version of the Planck Catalogue of Compact Sources (PCCS2). We divide our primary sample in two subsamples according to whether the sources lay (679 sources) or not (881 sources) inside the sky region defined by the Planck Galactic mask (fsky ˜ 60 per cent) and the area around the Magellanic Clouds. We find that the average fractional polarization of compact sources is approximately constant (with frequency) in both samples (with a weighted mean over all the channels of 3.08 per cent outside and 3.54 per cent inside the Planck mask). In the sky region outside the adopted mask, we also estimate the μ and σ parameters for the lognormal distribution of the fractional polarization, finding a weighted mean value over all the Planck frequency range of 1.0 for σ and 0.7 for μ (that would imply a weighted mean value for the median fractional polarization of 1.9 per cent).
Statistics of the fractional polarisation of compact radio sources in Planck maps
Bonavera, Laura; González-Nuevo, Joaquin; Argüeso, Francisco; Toffolatti, Luigi
2017-01-01
In this work we apply the stacking technique to estimate the average fractional polarisation from 30 to 353 GHz of a primary sample of 1560 compact sources - essentially all radio sources - detected in the 30 GHz Planck all-sky map and listed in the second version of the Planck Catalogue of Compact Sources (PCCS2). We divide our primary sample in two subsamples according to whether the sources lay (679 sources) or not (881 sources) inside the sky region defined by the Planck Galactic mask (fs...
Assessment of volume fraction and fabric in the distal radius using HR-pQCT.
Varga, P; Zysset, P K
2009-11-01
The aim of this study was to investigate the capabilities of the state of the art HR-pQCT technique to predict mineral content, volume fraction and fabric of trabecular bone structure compared to the gold standard microCT. Four cadaveric human forearms were scanned with HR-pQCT and the dissected radius epiphyses with microCT. After registering the images, bone mineral density (BMD), volume fraction (BV/TV) and fabric were computed on corresponding cubical regions of interest for both image sources. In particular, the effect of the segmentation procedure on BV/TV was analyzed. Assessment of fabric was performed with three different methods comparing their efficiency and robustness against resolution change. The results showed that in order to achieve optimal results at the lower image resolution, different filtering and thresholding approaches needed to be selected for different tasks. Therefore, to preserve BV/TV, the BMD-based volume fraction provided best match with the reference values of microCT, while in case of Mean Intercept Length (MIL) fabric a Gaussian filter and a histogram-based threshold were optimal. Using the latter, MIL was found to be more robust against resolution change than the other approaches. Additionally, we proposed a linear model for describing the mathematical transformation that the second order fabric tensor undergoes when the resolution of the input images changes. As a conclusion, we found that the investigated properties of trabecular bone structure can be adequately predicted from the lower resolution technique that is available in vivo for peripheral bones, when proper image processing and corrections are applied.
LENUS (Irish Health Repository)
Mullaney, L.
2014-01-10
Organ motion is a contributory factor to the variation in location of the prostate and organs at risk during a course of fractionated prostate radiation therapy (RT). A prospective randomized controlled trial was designed with the primary endpoint to provide evidence-based bladder-filling instructions to achieve a consistent bladder volume (BV) and thus reduce the bladder-related organ motion. The secondary endpoints were to assess the incidence of acute and late genitourinary (GU) and gastrointestinal (GI) toxicity for patients and patients’ satisfaction with the bladder-filling instructions.
Study of the free volume fraction in polylactic acid (PLA) by thermal analysis
Abdallah, A.; Benrekaa, N.
2015-10-01
The poly (lactic acid) or polylactide (PLA) is a biodegradable polymer with high modulus, strength and thermoplastic properties. In this work, the evolution of various properties of PLA is studied, such as glass transition temperature, mechanical modules and elongation percentage with the aim of investigating the free volume fraction. To do so, two thermal techniques have been used: the dynamic mechanical analysis (DMA) and dilatometry. The results obtained by these techniques are combined to go back to the structural properties of the studied material.
Energy Technology Data Exchange (ETDEWEB)
Ayranci, Isil [Department of Chemical Engineering, Middle East Technical University, 06531 Ankara (Turkey); Centre de Thermique de Lyon (CETHIL CNRS-INSA Lyon-UCBL), INSA de Lyon, 20 av. A. Einstein, 69621 Villeurbanne cedex (France); Vaillon, Rodolphe [Centre de Thermique de Lyon (CETHIL CNRS-INSA Lyon-UCBL), INSA de Lyon, 20 av. A. Einstein, 69621 Villeurbanne cedex (France); Selcuk, Nevin [Department of Chemical Engineering, Middle East Technical University, 06531 Ankara (Turkey)]. E-mail: selcuk@metu.edu.tr; Andre, Frederic [Centre de Thermique de Lyon (CETHIL CNRS-INSA Lyon-UCBL), INSA de Lyon, 20 av. A. Einstein, 69621 Villeurbanne cedex (France); Escudie, Dany [Centre de Thermique de Lyon (CETHIL CNRS-INSA Lyon-UCBL), INSA de Lyon, 20 av. A. Einstein, 69621 Villeurbanne cedex (France)
2007-03-15
An inversion scheme based on tomographic reconstruction of flame emission spectra has been developed for nonintrusive characterization of soot temperature and volume fraction fields within an optically thin axisymmetric flame by extracting characteristic information on soot refractive index from spectral gradients of emission spectra. Its performance is assessed by providing input data obtained from intensities simulated by a direct code based on experimental data for a flame available in the literature. Proposed method was found to be especially powerful in the near-infrared range for accurate prediction of flame properties where spectral variation of optical constants is significant.
Keller, Harald; Hope, Andrew; Meier, Gabriel; Davison, Matt
2013-08-01
To explore the potential of a novel dose-volume based metric to assist in the selection of optimal fractionation schedules for lung cancer patients. Selecting the dose per fraction that maximizes the therapeutic ratio via a linear-quadratic effect on normal tissue complication probability and tumor cell survival is an optimization problem. The mathematical solution reveals that the optimal fractionation schedule is determined by a generalized dose ratio between the normal tissue and the tumor, here termed the bifurcation number B, that can be derived from the dose-volume histogram of the normal tissue. The bifurcation number characterizes the volume effect of a normal tissue and its dependency on the fractionation schedule. The clinical relevance of the bifurcation number was evaluated in 46 patients previously treated for nonsmall cell lung cancer (NSCLC) according to various fractionation protocols. Bifurcation numbers were computed for both lung and esophagus as the normal tissues. The value of the bifurcation number determines whether the volume effect reverses the traditional radiobiological advantage of small dose per fraction for the normal tissue. If B is smaller than the ratio of alpha/beta ratios between normal tissue and tumor, then a single fraction is optimal; otherwise the optimal treatment is an infinite number of doses (hence the name "bifurcation" number). These fractionation schedules correspond clinically to hypo- and standard/hyperfractionation, respectively. Compared with traditional dose-volume metrics, the bifurcation number is a unitless ratio and independent of dose fractionation. The B-numbers derived from the clinical treatment plans are also strongly consistent with historically prescribed clinical fractionation protocols for NSCLC treatments. The B-numbers for esophagus and lung for all patients receiving a high dose per fraction protocol (>7.5 Gy/fraction) were all smaller than the B-numbers for the patients receiving standard 2 Gy/fraction
Regional Disparities in Online Map User Access Volume and Determining Factors
Li, R.; Yang, N.; Li, R.; Huang, W.; Wu, H.
2017-09-01
The regional disparities of online map user access volume (use `user access volume' in this paper to indicate briefly) is a topic of growing interest with the increment of popularity in public users, which helps to target the construction of geographic information services for different areas. At first place we statistically analysed the online map user access logs and quantified these regional access disparities on different scales. The results show that the volume of user access is decreasing from east to the west in China as a whole, while East China produces the most access volume; these cities are also the crucial economic and transport centres. Then Principal Component Regression (PCR) is applied to explore the regional disparities of user access volume. A determining model for Online Map access volume is proposed afterwards, which indicates that area scale is the primary determining factor for regional disparities, followed by public transport development level and public service development level. Other factors like user quality index and financial index have very limited influence on the user access volume. According to the study of regional disparities in user access volume, map providers can reasonably dispatch and allocate the data resources and service resources in each area and improve the operational efficiency of the Online Map server cluster.
Digital Mapping and Land Information Systems - Volume 6
DEFF Research Database (Denmark)
Frederiksen, Poul
1998-01-01
Introduction of digital mapping techniques in the 28 counties of Latvia related to the offices of the national mapping agency (State Land Service). Major components are: Training of regional staff, procurement of hard- and software, training of technical staff from State Land Service, HQ...
Uwano, Ikuko; Kudo, Kohsuke; Sato, Ryota; Ogasawara, Kuniaki; Kameda, Hiroyuki; Nomura, Jun-Ichi; Mori, Futoshi; Yamashita, Fumio; Ito, Kenji; Yoshioka, Kunihiro; Sasaki, Makoto
2017-08-01
The oxygen extraction fraction (OEF) is an effective metric to evaluate metabolic reserve in chronic ischemia. However, OEF is considered to be accurately measured only when using positron emission tomography (PET). Thus, we investigated whether OEF maps generated by magnetic resonance quantitative susceptibility mapping (QSM) at 7 Tesla enabled detection of OEF changes when compared with those obtained with PET. Forty-one patients with chronic stenosis/occlusion of the unilateral internal carotid artery or middle cerebral artery were examined using 7 Tesla-MRI and PET scanners. QSM images were obtained from 3-dimensional T2*-weighted images, using a multiple dipole-inversion algorithm. OEF maps were generated based on susceptibility differences between venous structures and brain tissues on QSM images. OEF ratios of the ipsilateral middle cerebral artery territory against the contralateral side were calculated on the QSM-OEF and PET-OEF images, using an anatomic template. The OEF ratio in the middle cerebral artery territory showed significant correlations between QSM-OEF and PET-OEF maps (r=0.69; P1.09, as determined by receiver operating characteristic analysis, showed a sensitivity and specificity of 0.82 and 0.86, respectively, for the substantial increase in the PET-OEF ratio. Absolute QSM-OEF values were significantly correlated with PET-OEF values in the patients with increased PET-OEF. OEF ratios on QSM-OEF images at 7 Tesla showed a good correlation with those on PET-OEF images in patients with unilateral steno-occlusive internal carotid artery/middle cerebral artery lesions, suggesting that noninvasive OEF measurement by MRI can be a substitute for PET. © 2017 American Heart Association, Inc.
Energy Technology Data Exchange (ETDEWEB)
Gama, Adriana M., E-mail: adrianaamg@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil); Rezende, Mirabel C., E-mail: mirabelmcr@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil); Dantas, Christine C., E-mail: christineccd@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil)
2011-11-15
We report the analysis of measurements of the complex magnetic permeability ({mu}{sub r}) and dielectric permittivity ({epsilon}{sub r}) spectra of a rubber radar absorbing material (RAM) with various MnZn ferrite volume fractions. The transmission/reflection measurements were carried out in a vector network analyzer. Optimum conditions for the maximum microwave absorption were determined by substituting the complex permeability and permittivity in the impedance matching equation. Both the MnZn ferrite content and the RAM thickness effects on the microwave absorption properties, in the frequency range of 2-18 GHz, were evaluated. The results show that the complex permeability and permittivity spectra of the RAM increase directly with the ferrite volume fraction. Reflection loss calculations by the impedance matching degree (reflection coefficient) show the dependence of this parameter on both thickness and composition of RAM. - Highlights: > Permeability and permittivity spectra of a MnZn ferrite RAM (2-18 GHz) are given. > Higher MnZn volume fraction favors increase of RAM/'s permeability and permittivity. > Minimum RL as a function of frequency, thickness and MnZn volume fraction given. > Higher thicknesses imply better absorption; optimum band shifts to lower frequencies. > For higher volume fractions, smaller thickness might offer better absorption (>10 GHz).
Volume fraction instability in an oscillating non-Brownian iso-dense suspension.
Directory of Open Access Journals (Sweden)
Roht Y.L.
2017-01-01
Full Text Available The instability of an iso-dense non-Brownian suspension of polystyrene beads of diameter 40 μm dispersed in a water-glycerol mixture submitted to a periodic square wave oscillating flow in a Hele-Shaw cell is studied experimentally. The instability gives rise to stationary bead concentration waves transverse to the flow. It has been observed for average particle volume fractions between 0.25 and 0.4, for periods of the square wave flow variation between 0.4 and 10 s and in finite intervals of the amplitude of the fluid displacement. The study shows that the wavelength λ increases roughly linearly with the amplitude of the oscillatory flow; on the other hand, λ is independent of the particle concentration and of the period of oscillation of the flow although the minimum threshold amplitude for observing the instability increases with the period.
DEFF Research Database (Denmark)
Lyngaae-Jørgensen, Jørgen; Utracki, Leszek
2003-01-01
A hypothesis providing a guideline for the development of immiscible polymer blends with co-continuous phase structure at very low critical volume fraction of one component is. postulated and experimentally verified. Based on a number of simplifying assumptions the following relation was derived......: phi(cr) = k(lambdagamma)(1-z)/(theta(b)(*))(z) where lambdagamma is a Deborah number and theta(b)(*) is a dimensionless break-up time. The equation parameters, k and z are constant that depend on the flow field hence on the blending equipment. For the studies an internal mixer with Walzenkneter......-type 30 mixing shafts was used. For this equipment the experimental values of the equation parameters, k = 1801 and z = 2.01, were found. (C) 2002 Elsevier Science Ltd. All rights reserved....
Effect of Mo microstructure on the critical volume fraction for conduction in Mo-alumina cermets
Energy Technology Data Exchange (ETDEWEB)
Kelso, J.F.; Higgins, R.R.; Krivda, F.J. [Alcoa Technical Center, Alcoa Center, Pennsylvania 15069 (United States)
1997-03-01
The microstructure of Mo in an alumina/frit matrix was found to be dependent on the initial partial sizes of the alumina and Mo powders, the glass content in the matrix ceramic, and the amount of moisture in the firing atmosphere. The Mo microstructure had a significant influence on the critical volume fraction for conductivity in these cermets. Coarser alumina powder, finer Mo powder, and higher glass content promoted coalescence of Mo into conductive networks at lower metal contents. Drier firing atmospheres produced a more coarsened Mo microstructure with a slight decrease in the amount of network contiguity, causing an increase in the amount required for electrical percolation. {copyright} {ital 1997 Materials Research Society.}
Directory of Open Access Journals (Sweden)
Terhzaz Jaouad
2014-04-01
Full Text Available This W presents a new technique of Dielectric Characterization of composites building materials. This technique is based on the modeling of an open coaxial cell with a mathematical formulation that links the admittances of the filled and empty cell to the complex permittivity ε* of materials characterization. We applied this technique to the dielectric characterization of some building materials powder in the frequency band (100MHz-4GHz. We also characterize some composite materials (sand- brick, cement- sand, and cement-brick depending on the volume fraction for Mobile Phone Frequencies. We made a comparison with the laws of mixtures to identify the most appropriate law to render the dielectric behavior of these materials.
Domsch, Sebastian; Mürle, Bettina; Weingärtner, Sebastian; Zapp, Jascha; Wenz, Frederik; Schad, Lothar R
2018-02-01
The oxygen extraction fraction (OEF) is an important biomarker for tissue-viability. MRI enables noninvasive estimation of the OEF based on the blood-oxygenation-level-dependent (BOLD) effect. Quantitative OEF-mapping is commonly applied using least-squares regression (LSR) to an analytical tissue model. However, the LSR method has not yet become clinically established due to the necessity for long acquisition times. Artificial neural networks (ANNs) recently have received increasing interest for robust curve-fitting and might pose an alternative to the conventional LSR method for reduced acquisition times. This study presents in vivo OEF mapping results using the conventional LSR and the proposed ANN method. In vivo data of five healthy volunteers and one patient with a primary brain tumor were acquired at 3T using a gradient-echo sampled spin-echo (GESSE) sequence. The ANN was trained with simulated BOLD data. In healthy subjects, the mean OEF was 36 ± 2% (LSR) and 40 ± 1% (ANN). The OEF variance within subjects was reduced from 8% to 6% using the ANN method. In the patient, both methods revealed a distinct OEF hotspot in the tumor area, whereas ANN showed less apparent artifacts in surrounding tissue. In clinical scan times, the ANN analysis enables OEF mapping with reduced variance, which could facilitate its integration into clinical protocols. Magn Reson Med 79:890-899, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
Clustered deep shadow maps for integrated polyhedral and volume rendering
Bornik, Alexander
2012-01-01
This paper presents a hardware-accelerated approach for shadow computation in scenes containing both complex volumetric objects and polyhedral models. Our system is the first hardware accelerated complete implementation of deep shadow maps, which unifies the computation of volumetric and geometric shadows. Up to now such unified computation was limited to software-only rendering . Previous hardware accelerated techniques can handle only geometric or only volumetric scenes - both resulting in the loss of important properties of the original concept. Our approach supports interactive rendering of polyhedrally bounded volumetric objects on the GPU based on ray casting. The ray casting can be conveniently used for both the shadow map computation and the rendering. We show how anti-aliased high-quality shadows are feasible in scenes composed of multiple overlapping translucent objects, and how sparse scenes can be handled efficiently using clustered deep shadow maps. © 2012 Springer-Verlag.
Mapping soil particle-size fractions: A comparison of compositional kriging and log-ratio kriging
Wang, Zong; Shi, Wenjiao
2017-03-01
Soil particle-size fractions (psf) as basic physical variables need to be accurately predicted for regional hydrological, ecological, geological, agricultural and environmental studies frequently. Some methods had been proposed to interpolate the spatial distributions of soil psf, but the performance of compositional kriging and different log-ratio kriging methods is still unclear. Four log-ratio transformations, including additive log-ratio (alr), centered log-ratio (clr), isometric log-ratio (ilr), and symmetry log-ratio (slr), combined with ordinary kriging (log-ratio kriging: alr_OK, clr_OK, ilr_OK and slr_OK) were selected to be compared with compositional kriging (CK) for the spatial prediction of soil psf in Tianlaochi of Heihe River Basin, China. Root mean squared error (RMSE), Aitchison's distance (AD), standardized residual sum of squares (STRESS) and right ratio of the predicted soil texture types (RR) were chosen to evaluate the accuracy for different interpolators. The results showed that CK had a better accuracy than the four log-ratio kriging methods. The RMSE (sand, 9.27%; silt, 7.67%; clay, 4.17%), AD (0.45), STRESS (0.60) of CK were the lowest and the RR (58.65%) was the highest in the five interpolators. The clr_OK achieved relatively better performance than the other log-ratio kriging methods. In addition, CK presented reasonable and smooth transition on mapping soil psf according to the environmental factors. The study gives insights for mapping soil psf accurately by comparing different methods for compositional data interpolation. Further researches of methods combined with ancillary variables are needed to be implemented to improve the interpolation performance.
Middle Atmosphere Program. Handbook for MAP, volume 25
Roper, R. G. (Editor)
1987-01-01
GLOBMET (the Global Meteor Observation System) was first proposed by the Soviet Geophysical Committee and was accepted by the Middle Atmosphere Program Steering Committee in 1982. While the atmospheric dynamics data from the system are of primary interest to MAP, GLOBMET also encompasses the astronomical radio and optical observations of meteoroids, and the physics of their interaction with the Earth's atmosphere. These astronomical observations and interactional physics with the Earth's atmosphere are discussed in detail.
Sui, Liansheng; Duan, Kuaikuai; Liang, Junli
2015-05-01
A new discrete fractional transform defined by the fractional order, periodicity and vector parameters is presented, which is named as the discrete multiple-parameter fractional angular transform. Based on this transform and two-coupled logistic map, a double-image encryption scheme is proposed. First, an enlarged image is obtained by connecting two plaintext images sequentially and scrambled by using a chaotic permutation process, in which the sequences of chaotic pairs generated by using the two-coupled logistic map. Then, the scrambled enlarged image is decomposed into two new components. Second, a chaotic random phase mask is generated based on the logistic map, with which one of two components is converted to the modulation phase mask. Another component is encoded into an interim matrix with the help of the modulation phase mask. Finally, the two-dimensional discrete multiple-parameter fractional angular transform is performed on the interim matrix to obtain the ciphertext with stationary white noise distribution. The proposed encryption scheme has an obvious advantage that no phase keys are used in the encryption and decryption process, which is convenient to key management. Moreover, the security of the cryptosystem can be enhanced by using extra parameters such as initial values of chaos functions, fractional orders and vector parameters of transform. Simulation results and security analysis verify the feasibility and effectiveness of the proposed scheme.
Effect of Fibre Volume Fraction on Mixed-Mode Fracture of a Fabric Carbon/Epoxy Composite
Feret, Victor; Ghiasi, Hossein; Hubert, Pascal
2013-08-01
Variation in fibre volume fraction is a common characteristic of composites made by an injection moulding process. The effect of this variation on fracture toughness is not yet fully investigated. This paper examines the fracture in fabric carbon/epoxy composite laminates under a wide range of combined mode-I and mode-II delamination. A total of 60 double cantilever beam and edge-notched flexure specimens are manufactured by resin transfer moulding with two different fibre volume fractions. It was observed that increasing the fibre volume fraction decreased the initiation fracture toughness in all mixed-mode ratios. This behaviour is believed to relate to the fact that the initiation fracture energy is dominantly absorbed by the resin-rich regions at the delamination tip. In contrast, an increase in fibre volume fraction was found to increase the propagation fracture toughness at high mode-I contribution where the fibre bridging is believed to be the major energy dissipating mechanism. Fractographic analysis also demonstrated that an increase in contribution of mode-II delamination is accompanied by a decrease in fibre bridging and an increase in shear hackles.
DEFF Research Database (Denmark)
Kelbaek, H; Svendsen, Jesper Hastrup; Aldershvile, J
2011-01-01
The stroke volume (SV) was determined by first passage radionuclide cardiography and the left ventricular ejection fraction (LVEF) by multigated radionuclide cardiography in 20 patients with ischemic heart disease. The results were evaluated against those obtained by the invasive dye dilution or ...
Energy Technology Data Exchange (ETDEWEB)
Murthy, Vedang, E-mail: vmurthy@actrec.gov.in [Department of Radiation Oncology and Medical Physics, Tata Memorial Hospital and Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Mumbai (India); Shukla, Pragya; Adurkar, Pranjal; Master, Zubin; Mahantshetty, Umesh; Shrivastava, Shyamkishore [Department of Radiation Oncology and Medical Physics, Tata Memorial Hospital and Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Mumbai (India)
2012-09-01
Purpose: To evaluate whether information from the initial fractions can determine which patients are likely to consistently exceed their planning dose-volume constraints during the course of radiotherapy for prostate cancer. Methods and Materials: Ten patients with high-risk prostate cancer were treated with helical tomotherapy to a dose of 60 Gy in 20 fractions. The prostate, rectum, and bladder were recontoured on their daily megavoltage computed tomography scans and the dose was recalculated. The bladder and rectal volumes (in mL) receiving {>=}100% and {>=}70% of the prescribed dose in each fraction and in the original plans were recorded. A fraction for which the difference between planned and delivered was more than 2 mL was considered a volume failure. Similarly if the difference in the planned and delivered maximum dose (D{sub max}) was {>=}1% for the rectum and bladder, the fraction was considered a dose failure. Each patient's first 3 to 5 fractions were analyzed to determine if they correctly identified those patients who would consistently fail (i.e., {>=}20% of fractions) during the course of their radiotherapy. Results: Six parameters were studied; the rectal volume (RV) and bladder volumes (BV) (in mL) received {>=}100% and {>=}70% of the prescribed dose and maximum dose to 2 mL of the rectum and bladder. This was given by RV{sub 100}, RV{sub 70}, BV{sub 100}, BV{sub 70}, RD{sub max}, and BD{sub max}, respectively. When more than 1 of the first 3 fractions exceed the planning constraint as defined, it accurately predicts consistent failures through the course of the treatment. This method is able to correctly identify the consistent failures about 80% (RV{sub 70}, BV{sub 100}, and RV{sub 100}), 90% (BV{sub 70}), and 100% (RD{sub max} and BD{sub max}) of the times. Conclusions: This study demonstrates the feasibility of a method accurately identifying patients who are likely to consistently exceed the planning constraints during the course of
A Volume-Fraction Based Two-Phase Constitutive Model for Blood
Energy Technology Data Exchange (ETDEWEB)
Zhao, Rui (Carnegie-Mellon Univ.); Massoudi, Mehrdad; Hund, S.J. (Carnegie-Mellon Univ.); •Antaki, J.F. (Carnegie-Mellon Univ.)
2008-06-01
Mechanically-induced blood trauma such as hemolysis and thrombosis often occurs at microscopic channels, steps and crevices within cardiovascular devices. A predictive mathematical model based on a broad understanding of hemodynamics at micro scale is needed to mitigate these effects, and is the motivation of this research project. Platelet transport and surface deposition is important in thrombosis. Microfluidic experiments have previously revealed a significant impact of red blood cell (RBC)-plasma phase separation on platelet transport [5], whereby platelet localized concentration can be enhanced due to a non-uniform distribution of RBCs of blood flow in a capillary tube and sudden expansion. However, current platelet deposition models either totally ignored RBCs in the fluid by assuming a zero sample hematocrit or treated them as being evenly distributed. As a result, those models often underestimated platelet advection and deposition to certain areas [2]. The current study aims to develop a two-phase blood constitutive model that can predict phase separation in a RBC-plasma mixture at the micro scale. The model is based on a sophisticated theory known as theory of interacting continua, i.e., mixture theory. The volume fraction is treated as a field variable in this model, which allows the prediction of concentration as well as velocity profiles of both RBC and plasma phases. The results will be used as the input of successive platelet deposition models.
Caliman, R.
2017-08-01
This paper contains an analysis of the factors that have an influence on the tribological characteristics of the composite material sintered with metal matrix reinforced with carbon fibers. These composites are used generally if it’s needed the wear resistant materials, whereas these composites have high specific strength in conjunction with a good corrosion resistance at low densities and some self-lubricating properties. Through the knowledge of the better tribological properties of the materials and their behavior to wear, can be generated by dry and the wet friction. Thus, where necessary the use of high temperature resistant material with low friction between the elements, carbon fiber composite materials are very suitable because they have: mechanical strength and good ductility, melting temperature on the higher values, higher electrical and thermal conductivity, lower wear speed and lower friction forces. For this purpose, this paper also contains an experimental program based on the evidence of formaldehyde resin made from fiber reinforced Cu-carbon with the aim to specifically determine the volume of fibers fraction for the consolidation of the composite material. In order to determine the friction coefficient and the wear rates of the various fiber reinforced polymer mixtures of carbon have been used special devices with needle-type with steel disc. These tests were conducted in the atmosphere at the room temperature without external lubrication study taking into consideration the sliding different speeds with constant loading task.
A framework of whole heart extracellular volume fraction estimation for low dose cardiac CT images
Chen, Xinjian; Summers, Ronald M.; Nacif, Marcelo Souto; Liu, Songtao; Bluemke, David A.; Yao, Jianhua
2012-02-01
Cardiac magnetic resonance imaging (CMRI) has been well validated and allows quantification of myocardial fibrosis in comparison to overall mass of the myocardium. Unfortunately, CMRI is relatively expensive and is contraindicated in patients with intracardiac devices. Cardiac CT (CCT) is widely available and has been validated for detection of scar and myocardial stress/rest perfusion. In this paper, we sought to evaluate the potential of low dose CCT for the measurement of myocardial whole heart extracellular volume (ECV) fraction. A novel framework was proposed for CCT whole heart ECV estimation, which consists of three main steps. First, a shape constrained graph cut (GC) method was proposed for myocardium and blood pool segmentation for post-contrast image. Second, the symmetric Demons deformable registrations method was applied to register pre-contrast to post-contrast images. Finally, the whole heart ECV value was computed. The proposed method was tested on 7 clinical low dose CCT datasets with pre-contrast and post-contrast images. The preliminary results demonstrated the feasibility and efficiency of the proposed method.
Kailasanathan, Ranjith Kumar Abhinavam
2014-05-20
Soot surface temperature and volume fraction are measured in ethylene/air coflowing laminar diffusion flames at high pressures, diluted with one of four diluents (argon, helium, nitrogen, and carbon dioxide) using a two-color technique. Both temperature and soot measurements presented are line-of-sight averages. The results aid in understanding the kinetic and thermodynamic behavior of the soot formation and oxidation chemistry with changes in diluents, ultimately leading to possible methods of reducing soot emission from practical combustion hardware. The diluted fuel and coflow exit velocities (top-hat profiles) were matched at all pressures to minimize shear effects. In addition to the velocity-matched flow rates, the mass fluxes were held constant for all pressures. Addition of a diluent has a pronounced effect on both the soot surface temperature and volume fraction, with the helium diluted flame yielding the maximum and carbon dioxide diluted flame yielding minimum soot surface temperature and volume fraction. At low pressures, peak soot volume fraction exists at the tip of the flame, and with an increase in pressure, the location shifts lower to the wings of the flame. Due to the very high diffusivity of helium, significantly higher temperature and volume fraction are measured and explained. Carbon dioxide has the most dramatic soot suppression effect. By comparing the soot yield with previously measured soot precursor concentrations in the same flame, it is clear that the lower soot yield is a result of enhanced oxidation rates rather than a reduction in precursor formation. Copyright © 2014 Taylor & Francis Group, LLC.
Chen, Yin-Yin; Ren, Dao-Yuan; Zeng, Meng-Su; Yang, Shan; Yun, Hong; Fu, Cai-Xia; Ge, Jun-Bo; Jin, Hang; Qian, Ju-Ying; Zhang, Wei-Guo
2016-10-01
To investigate whether myocardial extracellular volume fraction (ECV) measurement by cardiac MR is indicative of myocardial injury, angiographic collateral flow, and functional recovery in patients with chronic total coronary occlusion (CTO). A total of 50 CTO patients undergoing 1.5 Tesla MR were prospectively enrolled, and 28 underwent a second MR 6 months after revascularization. T1-mapping based indices, including pre- and postcontrast T1 values and ECV, were obtained from infarcted and non-infarcted myocardium, myocardial segments, and coronary territory. The severity of myocardial injury was rated by transmurality extent of infarction (TEI) and regional wall motion abnormalities (RWMA) score. Angiographic collateral flow was evaluated using Rentrop classification. Improvement in segmental wall motion at 6 months was also assessed. ECV and postcontrast T1 value significantly outperformed precontrast T1 value for identifying myocardial infarction (area under the receiver operating characteristic curve [AUC]: 0.998 and 0.953 versus 0.824, all P < 0.02). Myocardial ECV was strongly correlated with TEI (P = 0.000), RWMA score (P = 0.000), and collateral classification (P = 0.007 for left anterior descending artery [LAD] territory, P = 0.001 for non-LAD territory). Furthermore, the likelihood of functional recovery was better predicted by ECV than by late gadolinium enhancement (LGE) (AUC: 0.76 versus 0.68, P < 0.02). Myocardial ECV may be a useful surrogate to assess myocardial injury and angiographic collateral flow in CTO, and ECV provides incremental value to LGE in assessing functional recovery after revascularization. J. MAGN. RESON. IMAGING 2016;44:972-982. © 2016 International Society for Magnetic Resonance in Medicine.
Directory of Open Access Journals (Sweden)
Josiane Hélou
2013-01-01
Full Text Available Background: Fractionated carbon dioxide (CO 2 lasers are a new treatment modality for skin resurfacing. The cosmetic rejuvenation market abounds with various injectable devices (poly-L-lactic acid, polymethyl-methacrylate, collagens, hyaluronic acids, silicone. The objective of this study is to examine the efficacy and safety of 10,600-nm CO 2 fractional laser on facial skin with previous volume injections. Materials and Methods: This is a retrospective study including 14 patients treated with fractional CO 2 laser and who have had previous facial volume restoration. The indication for the laser therapy, the age of the patients, previous facial volume restoration, and side effects were all recorded from their medical files. Objective assessments were made through clinical physician global assessment records and improvement scores records. Patients′ satisfaction rates were also recorded. Results: Review of medical records of the 14 patients show that five patients had polylactic acid injection prior to the laser session. Eight patients had hyaluronic acid injection prior to the laser session. Two patients had fat injection, two had silicone injection and one patient had facial thread lift. Side effects included pain during the laser treatment, post-treatment scaling, post-treatment erythema, hyperpigmentation which spontaneously resolved within a month. Concerning the previous facial volume restoration, no granulomatous reactions were noted, no facial shape deformation and no asymmetry were encountered whatever the facial volume product was. Conclusion: CO 2 fractional laser treatments do not seem to affect facial skin which had previous facial volume restoration with polylactic acid for more than 6 years, hyaluronic acid for more than 0.5 year, silicone for more than 6 years, or fat for more than 1.4 year. Prospective larger studies focusing on many other variables (skin phototype, injected device type are required to achieve better
Directory of Open Access Journals (Sweden)
Weijie Yan
2017-05-01
Full Text Available A method for simultaneously visualizing the two-dimensional distributions of temperature and soot volume fraction in an ethylene flame was presented. A single-color charge-coupled device (CCD camera was used to capture the flame image in the visible spectrum considering the broad-response spectrum of the R and G bands of the camera. The directional emissive power of the R and G bands were calibrated and used for measurement. Slightly increased temperatures and reduced soot concentration were predicted in the central flame without self-absorption effects considered, an iterative algorithm was used for eliminating the effect of self-absorption. Nine different cases were presented in the experiment to demonstrate the effects of fuel mass flow rate and oxygen concentration on temperature and soot concentration in three different atmospheres. For ethylene combustion in pure-air atmosphere, as the fuel mass flow rate increased, the maximum temperature slightly decreased, and the maximum soot volume fraction slightly increased. For oxygen fractions of 30%, 40%, and 50% combustion in O2/N2 oxygen-enhanced atmospheres, the maximum flame temperatures were 2276, 2451, and 2678 K, whereas combustion in O2/CO2 atmospheres were 1916, 2322, and 2535 K. The maximum soot volume fractions were 4.5, 7.0, and 9.5 ppm in oxygen-enriched O2/N2 atmosphere and 13.6, 15.3, and 14.8 ppm in oxygen-enriched O2/CO2 atmosphere. Compared with the O2/CO2 atmosphere, combustion in the oxygen-enriched O2/N2 atmosphere produced higher flame temperature and larger soot volume fraction. Preliminary results indicated that this technique is reliable and can be used for combustion diagnosis.
Foetal fractional thigh volume: an early 3D ultrasound marker of neonatal adiposity.
Roelants, J A; Vermeulen, M J; Koning, I V; Groenenberg, I A L; Willemsen, S P; Hokken-Koelega, A C S; Joosten, K F M; Reiss, I K M; Steegers-Theunissen, R P M
2017-08-01
The predisposition for obesity is suggested to originate in the prenatal period. Prenatal markers are needed to identify foetuses at risk for neonatal adiposity, as early marker of childhood obesity. The aim of this study is to assess the association between foetal fractional thigh volume (TVol) and neonatal percentage fat mass from mid-gestation onward. In this perinatal cohort study, singleton pregnancies with term born infants were included. Foetal TVol was measured on three-dimensional ultrasound scans (3D US) obtained at 22, 26 and 32 weeks of gestation. Neonatal body composition measurement (percentage body fat (%BF)) was planned between 42+0 and 42+6 -week postmenstrual age. Cross-sectional and longitudinal linear regression analyses were performed. Seventy-nine mother-child pairs were included. Median (interquartile range) TVol increased from 7.6 (7.1; 8.5) cm3 at 22 weeks to 36.5 (33.8; 40.9) cm3 at 32 weeks. Median neonatal %BF was 14.3% (11.7; 17.0). TVol at 22 weeks (β = -1.58, 95% CI -2.45; -0.70, explained variance 31%) was negatively associated with %BF, but no associations were found at 26 and 32 weeks of gestation. TVol growth between 22 and 32 weeks of gestation (explained variance 18%) was also statistically significantly negatively associated with %BF. Foetal TVol is a promising 3D US marker for prediction of neonatal adiposity from mid-gestation onward. © 2017 World Obesity Federation.
Luo, Kun; Hu, Chenshu; Wu, Fan; Fan, Jianren
2017-05-01
In the present work, a direct numerical simulation (DNS) of dilute particulate flow in a turbulent boundary layer has been conducted, containing thousands of finite-sized solid rigid particles. The particle surfaces are resolved with the multi-direct forcing immersed-boundary method. This is, to the best of the authors' knowledge, the first DNS study of a turbulent boundary layer laden with finite-sized particles. The particles have a diameter of approximately 11.3 wall units, a density of 3.3 times that of the fluid, and a solid volume fraction of 1/1000. The simulation shows that the onset and the completion of the transition processes are shifted earlier with the inclusion of the solid phase and that the resulting streamwise mean velocity of the boundary layer in the particle-laden case is almost consistent with the results of the single-phase case. At the same time, relatively stronger particle movements are observed in the near-wall regions, due to the driving of the counterrotating streamwise vortexes. As a result, increased levels of dissipation occur on the particle surfaces, and the root mean square of the fluctuating velocities of the fluid in the near-wall regions is decreased. Under the present parameters, including the particle Stokes number St + = 24 and the particle Reynolds number Re p = 33 based on the maximum instantaneous fluid-solid velocity lag, no vortex shedding behind the particle is observed. Lastly, a trajectory analysis of the particles shows the influence of turbophoresis on particle wall-normal concentration, and the particles that originated between y + = 60 and 2/3 of the boundary-layer thickness are the most influenced.
Directory of Open Access Journals (Sweden)
Jian-feng Zhao
2017-01-01
Full Text Available This paper presents a three-dimensional autonomous chaotic system with high fraction dimension. It is noted that the nonlinear characteristic of the improper fractional-order chaos is interesting. Based on the continuous chaos and the discrete wavelet function map, an image encryption algorithm is put forward. The key space is formed by the initial state variables, parameters, and orders of the system. Every pixel value is included in secret key, so as to improve antiattack capability of the algorithm. The obtained simulation results and extensive security analyses demonstrate the high level of security of the algorithm and show its robustness against various types of attacks.
Yarnykh, V.; Korostyshevskaya, A.
2017-08-01
Macromolecular proton fraction (MPF) is a biophysical parameter describing the amount of macromolecular protons involved into magnetization exchange with water protons in tissues. MPF represents a significant interest as a magnetic resonance imaging (MRI) biomarker of myelin for clinical applications. A recent fast MPF mapping method enabled clinical translation of MPF measurements due to time-efficient acquisition based on the single-point constrained fit algorithm. However, previous MPF mapping applications utilized only 3 Tesla MRI scanners and modified pulse sequences, which are not commonly available. This study aimed to test the feasibility of MPF mapping implementation on a 1.5 Tesla clinical scanner using standard manufacturer’s sequences and compare the performance of this method between 1.5 and 3 Tesla scanners. MPF mapping was implemented on 1.5 and 3 Tesla MRI units of one manufacturer with either optimized custom-written or standard product pulse sequences. Whole-brain three-dimensional MPF maps obtained from a single volunteer were compared between field strengths and implementation options. MPF maps demonstrated similar quality at both field strengths. MPF values in segmented brain tissues and specific anatomic regions appeared in close agreement. This experiment demonstrates the feasibility of fast MPF mapping using standard sequences on 1.5 T and 3 T clinical scanners.
Zhao, Hongjie; Zhong, Zhi; Fang, Weiwei; Xie, Hong; Zhang, Yabin; Shan, Mingguang
2016-09-01
A double-image encryption method is reported using chaotic maps, nonlinear non-DC joint transform correlator (JTC), and fractional Fourier transform (FrFT). The double images are converted into the amplitude and phase of a synthesized function through the application of chaotic pixel scrambling. The synthesized function bonded with a chaotic random phase mask (CRPM) and another different CRPM serve as the input signal of the JTC architecture in the fractional Fourier domain to obtain a real-valued encrypted image. The nonlinear and non-DC operation is also done to improve the security and decrypted image quality. The parameters in joint FrFT correlator and chaotic map serve as the encrypted keys. Numerical simulations have been done to demonstrate the feasibility and validity of this algorithm.
Hematoma volume measurement in gradient echo MRI using quantitative susceptibility mapping.
Wang, Shuo; Lou, Min; Liu, Tian; Cui, Deqi; Chen, Xiaomei; Wang, Yi
2013-08-01
A novel quantitative susceptibility mapping (QSM) processing technology has been developed to map tissue susceptibility property without blooming artifacts. We hypothesize that hematoma volume measurement on QSM is independent of imaging parameters, eliminating its echo time dependence on gradient echo MRI. Gradient echo MRI of 16 patients with intracerebral hemorrhage was processed with susceptibility-weighted imaging, R2* (=1/T2*) mapping, and QSM at various echo times. Hematoma volumes were measured from these images. Linear regression of hematoma volume versus echo time showed substantial slopes for gradient echo magnitude (0.45±0.31 L/s), susceptibility-weighted imaging (0.52±0.46), and R2* (0.39±0.30) but nearly zero slope for QSM (0.01±0.05). At echo time=20 ms, hematoma volume on QSM was 0.80× that on gradient echo magnitude image (R2=0.99). QSM can provide reliable measurement of hematoma volume, which can be performed rapidly and accurately using a semiautomated segmentation tool.
Wilson, S. A.; Libor, Z.; Skordos, A. A.; Zhang, Q.
2009-03-01
The dc conductivities of several different types of nanoparticles (nickel, barium titanate and magnetite) suspended in both silicone and perfluorinated oils have been measured and contrasted. Enhanced dc conductivity through interaction between the particles and the fluid has been demonstrated, even at quite moderate fields, and different types of nanoparticles have been shown to exhibit different behavioural trends. Whilst the dc enhancement is partly related to the concentration (or spatial arrangement) of the particles as expected, there is clear evidence that energy-activated (electric field activated) processes also play a major role. It can be said that effective-medium theories based solely on the electrical properties and volume fractions of the component materials have limited applicability when assessing the dc conductivities of these nanoparticle-fluid combinations at low volume fractions.
Loury, Chloé; Lanari, Pierre; Rolland, Yann; Guillot, Stéphane; Ganino, Clément
2014-05-01
Understanding geodynamic processes in subduction zones and mountains belts relies on the reconstruction of precise pressure-temperature paths (P-T paths) from metamorphic rocks. Most P-T paths are obtained using quantitative thermobarometry such as forward thermodynamics models. The question of the scale of the equilibration volume is of prime importance because its chemistry is used as input for the calculation of P-T sections. In chemically homogeneous rocks the bulk rock may be obtained either by ICP-MS or XRF analysis on whole rocks. For chemically heterogeneous rocks, containing different mineral assemblages and/or a high proportion of zoned minerals, the concept of local effective bulk (LEB) is essential. In the last 10 years, X-ray micro-mapping methods have been developed in this aim. Here we show how standardized X-ray maps can be used to estimate the equilibration volume at the pressure peak in an eclogite sample. The study area lies in the Atbashi range, in Kyrgyzstan, along the South-Tianshan carboniferous suture of the Central Asian Orogenic Belt with the Tarim block. We use the micro-mapping approach to unravel the P-T path of a mafic eclogite containing mm-scale garnet porphyroblasts. Quantitative compositional maps of a garnet and its surrounding matrix are obtained from standardized X-ray maps processed with the XMapTools program (Lanari et al, 2014). By using these maps we measured the LEB corresponding to the different stages of garnet growth. The equilibration volume is then modeled using the local compositions (extrapolated in 3D) combined with Gibbs free energy minimization. Our model suggests that equilibrium conditions are attained for chemistry made of 90% of garnet and 10% of matrix. P-T sections are calculated from the core of the garnet to the rim taking into account the fractionation at each stage of garnet growth by changing the bulk composition. We obtained the following P-T path: (1) garnet core crystallization during prograde stage
Directory of Open Access Journals (Sweden)
K. M. Kim
2016-06-01
Full Text Available Traditional field methods for measuring tree heights are often too costly and time consuming. An alternative remote sensing approach is to measure tree heights from digital stereo photographs which is more practical for forest managers and less expensive than LiDAR or synthetic aperture radar. This work proposes an estimation of stand height and forest volume(m3/ha using normalized digital surface model (nDSM from high resolution stereo photography (25cm resolution and forest type map. The study area was located in Mt. Maehwa model forest in Hong Chun-Gun, South Korea. The forest type map has four attributes such as major species, age class, DBH class and crown density class by stand. Overlapping aerial photos were taken in September 2013 and digital surface model (DSM was created by photogrammetric methods(aerial triangulation, digital image matching. Then, digital terrain model (DTM was created by filtering DSM and subtracted DTM from DSM pixel by pixel, resulting in nDSM which represents object heights (buildings, trees, etc.. Two independent variables from nDSM were used to estimate forest stand volume: crown density (% and stand height (m. First, crown density was calculated using canopy segmentation method considering live crown ratio. Next, stand height was produced by averaging individual tree heights in a stand using Esri’s ArcGIS and the USDA Forest Service’s FUSION software. Finally, stand volume was estimated and mapped using aerial photo stand volume equations by species which have two independent variables, crown density and stand height. South Korea has a historical imagery archive which can show forest change in 40 years of successful forest rehabilitation. For a future study, forest volume change map (1970s–present will be produced using this stand volume estimation method and a historical imagery archive.
Kim, K. M.
2016-06-01
Traditional field methods for measuring tree heights are often too costly and time consuming. An alternative remote sensing approach is to measure tree heights from digital stereo photographs which is more practical for forest managers and less expensive than LiDAR or synthetic aperture radar. This work proposes an estimation of stand height and forest volume(m3/ha) using normalized digital surface model (nDSM) from high resolution stereo photography (25cm resolution) and forest type map. The study area was located in Mt. Maehwa model forest in Hong Chun-Gun, South Korea. The forest type map has four attributes such as major species, age class, DBH class and crown density class by stand. Overlapping aerial photos were taken in September 2013 and digital surface model (DSM) was created by photogrammetric methods(aerial triangulation, digital image matching). Then, digital terrain model (DTM) was created by filtering DSM and subtracted DTM from DSM pixel by pixel, resulting in nDSM which represents object heights (buildings, trees, etc.). Two independent variables from nDSM were used to estimate forest stand volume: crown density (%) and stand height (m). First, crown density was calculated using canopy segmentation method considering live crown ratio. Next, stand height was produced by averaging individual tree heights in a stand using Esri's ArcGIS and the USDA Forest Service's FUSION software. Finally, stand volume was estimated and mapped using aerial photo stand volume equations by species which have two independent variables, crown density and stand height. South Korea has a historical imagery archive which can show forest change in 40 years of successful forest rehabilitation. For a future study, forest volume change map (1970s-present) will be produced using this stand volume estimation method and a historical imagery archive.
Ming Kun Yew; Hilmi Bin Mahmud; Bee Chin Ang; Ming Chian Yew
2015-01-01
This paper presents the effects of low volume fraction (Vf) of polyvinyl alcohol (PVA) fibers on the mechanical properties of oil palm shell (OPS) high strength lightweight concrete mixtures. The slump, density, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity under various curing conditions have been measured and evaluated. The results indicate that an increase in PVA fibers decreases the workability of the concrete and decreases the density slig...
Grzegorz Kossakowski, Paweł; Wciślik, Wiktor
2017-10-01
The paper is concerned with the nucleation, growth and coalescence of microdefects in the form of voids in S235JR steel. The material is known to be one of the basic steel grades commonly used in the construction industry. The theory and methods of damage mechanics were applied to determine and describe the failure mechanisms that occur when the material undergoes deformation. Until now, engineers have generally employed the Gurson-Tvergaard- Needleman model. This material model based on damage mechanics is well suited to define and analyze failure processes taking place in the microstructure of S235JR steel. It is particularly important to determine the critical void volume fraction fc , which is one of the basic parameters of the Gurson-Tvergaard-Needleman material model. As the critical void volume fraction fc refers to the failure stage, it is determined from the data collected for the void coalescence phase. A case of multi-axial stresses is considered taking into account the effects of spatial stress state. In this study, the parameter of stress triaxiality η was used to describe the failure phenomena. Cylindrical tensile specimens with a circumferential notch were analysed to obtain low values of initial stress triaxiality (η = 0.556 of the range) in order to determine the critical void volume fraction fc . It is essential to emphasize how unique the method applied is and how different it is from the other more common methods involving parameter calibration, i.e. curve-fitting methods. The critical void volume fraction fc at void coalescence was established through digital image analysis of surfaces of S235JR steel, which involved studying real, physical results obtained directly from the material tested.
Liu, Dian; Steingoetter, Andreas; Curcic, Jelena; Kozerke, Sebastian
2018-01-01
To investigate and exploit the effect of intravoxel off-resonance compartments in the triple-echo steady-state (TESS) sequence without fat suppression for T2 mapping and to leverage the results for fat fraction quantification. In multicompartment tissue, where at least one compartment is excited off-resonance, the total signal exhibits periodic modulations as a function of echo time (TE). Simulated multicompartment TESS signals were synthesized at various TEs. Fat emulsion phantoms were prepared and scanned at the same TE combinations using TESS. In vivo knee data were obtained with TESS to validate the simulations. The multicompartment effect was exploited for fat fraction quantification in the stomach by acquiring TESS signals at two TE combinations. Simulated and measured multicompartment signal intensities were in good agreement. Multicompartment effects caused erroneous T2 offsets, even at low water-fat ratios. The choice of TE caused T2 variations of as much as 28% in cartilage. The feasibility of fat fraction quantification to monitor the decrease of fat content in the stomach during digestion is demonstrated. Intravoxel off-resonance compartments are a confounding factor for T2 quantification using TESS, causing errors that are dependent on the TE. At the same time, off-resonance effects may allow for efficient fat fraction mapping using steady-state imaging. Magn Reson Med 79:423-429, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
Mapping the Potentially Affected Fraction (PAF) of species as an indicator of generic toxic stress
Klepper O; Meent D van de; ECO
1997-01-01
The Potentially Affected Fraction (PAF) is the fraction of species exposed above the no-effect concentration (NOEC). The PAF is a measure that allows a comparison in toxic stress between substances and areas. In the report the PAF is calculated for four heavy metals (cadmium, copper, lead and zinc)
Directory of Open Access Journals (Sweden)
Marcel Schwieder
2014-04-01
Full Text Available Anthropogenic interventions in natural and semi-natural ecosystems often lead to substantial changes in their functioning and may ultimately threaten ecosystem service provision. It is, therefore, necessary to monitor these changes in order to understand their impacts and to support management decisions that help ensuring sustainability. Remote sensing has proven to be a valuable tool for these purposes, and especially hyperspectral sensors are expected to provide valuable data for quantitative characterization of land change processes. In this study, simulated EnMAP data were used for mapping shrub cover fractions along a gradient of shrub encroachment, in a study region in southern Portugal. We compared three machine learning regression techniques: Support Vector Regression (SVR; Random Forest Regression (RF; and Partial Least Squares Regression (PLSR. Additionally, we compared the influence of training sample size on the prediction performance. All techniques showed reasonably good results when trained with large samples, while SVR always outperformed the other algorithms. The best model was applied to produce a fractional shrub cover map for the whole study area. The predicted patterns revealed a gradient of shrub cover between regions affected by special agricultural management schemes for nature protection and areas without land use incentives. Our results highlight the value of EnMAP data in combination with machine learning regression techniques for monitoring gradual land change processes.
Hendricks, S.; Hoppmann, M.; Hunkeler, P. A.; Kalscheuer, T.; Gerdes, R.
2015-12-01
In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise and accumulate beneath nearby sea ice to form a several meter thick sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator for ice - ocean interactions. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and sub-ice platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions from platelet-layer conductivities using Archie's Law. The thickness results agreed well with drill-hole validation datasets within the uncertainty range, and the ice-volume fraction also yielded plausible results. Our findings imply that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties. However, we emphasize that the successful application of this technique requires a break with traditional EM sensor calibration strategies due to the need of absolute calibration with respect to a physical forward model.
DEFF Research Database (Denmark)
Ghanbarpour, S.; Mazaheripour, H.; Mirmoradi, S. H.
2010-01-01
is to investigate the effects of type and volume fraction of steel fiber on the compressive strength, split tensile strength, flexural strength and modulus of elasticity of steel fiber reinforced self-compacting concrete (SFRSCC). Design/methodology/approach – For this purpose, Micro wire and Wave type steel fibers...... with l/d ratios of 50 were used. Three different fiber volumes were added to concrete mixes at 0.5, 0.75 and 1 per cent by volume of SCC. Six different SFRSCC mixes were prepared. After 28 days of curing, compressive, split and flexural strength and modulus of elasticity were determined. Findings...... – It was found that, inclusion of steel fibers significantly affect the split tensile and flexural strength of SCC accordance with type and vf. Besides, mathematical expressions were developed to estimate the flexural, modulus of elasticity and split tensile strength of SFRSCCs regarding of compressive strength...
Mapping Regional Differences of Local Pressure-Volume Curves With Electrical Impedance Tomography.
Beda, Alessandro; Carvalho, Alysson R; Carvalho, Nadja C; Hammermüller, Sören; Amato, Marcelo B P; Muders, Thomas; Gittel, Claudia; Noreikat, Katharina; Wrigge, Hermann; Reske, Andreas W
2017-04-01
Lung-protective mechanical ventilation aims to prevent alveolar collapse and overdistension, but reliable bedside methods to quantify them are lacking. We propose a quantitative descriptor of the shape of local pressure-volume curves derived from electrical impedance tomography, for computing maps that highlight the presence and location of regions of presumed tidal recruitment (i.e., elastance decrease during inflation, pressure-volume curve with upward curvature) or overdistension (i.e., elastance increase during inflation, downward curvature). Secondary analysis of experimental cohort study. University research facility. Twelve mechanically ventilated pigs. After induction of acute respiratory distress syndrome by hydrochloric acid instillation, animals underwent a decremental positive end-expiratory pressure titration (steps of 2 cm H2O starting from ≥ 26 cm H2O). Electrical impedance tomography-derived maps were computed at each positive end-expiratory pressure-titration step, and whole-lung CT taken every second steps. Airway flow and pressure were recorded to compute driving pressure and elastance. Significant correlations between electrical impedance tomography-derived maps and positive end-expiratory pressure indicate that, expectedly, tidal recruitment increases in dependent regions with decreasing positive end-expiratory pressure (p electrical impedance tomography-derived tidal recruitment with poorly aerated regions (r = 0.43; p electrical impedance tomography-derived overdistension with nonaerated regions at lower positive end-expiratory pressures and with hyperaerated regions at higher positive end-expiratory pressures (r ≥ 0.72; p electrical impedance tomography-derived maps showed nonnegligible regions of presumed overdistension and tidal recruitment. Electrical impedance tomography-derived maps of pressure-volume curve shapes allow to detect regions in which elastance changes during inflation. This could promote individualized mechanical
Roshani, G H; Karami, A; Salehizadeh, A; Nazemi, E
2017-11-01
The problem of how to precisely measure the volume fractions of oil-gas-water mixtures in a pipeline remains as one of the main challenges in the petroleum industry. This paper reports the capability of Radial Basis Function (RBF) in forecasting the volume fractions in a gas-oil-water multiphase system. Indeed, in the present research, the volume fractions in the annular three-phase flow are measured based on a dual energy metering system including the 152Eu and 137Cs and one NaI detector, and then modeled by a RBF model. Since the summation of volume fractions are constant (equal to 100%), therefore it is enough for the RBF model to forecast only two volume fractions. In this investigation, three RBF models are employed. The first model is used to forecast the oil and water volume fractions. The next one is utilized to forecast the water and gas volume fractions, and the last one to forecast the gas and oil volume fractions. In the next stage, the numerical data obtained from MCNP-X code must be introduced to the RBF models. Then, the average errors of these three models are calculated and compared. The model which has the least error is picked up as the best predictive model. Based on the results, the best RBF model, forecasts the oil and water volume fractions with the mean relative error of less than 0.5%, which indicates that the RBF model introduced in this study ensures an effective enough mechanism to forecast the results. Copyright © 2017 Elsevier Ltd. All rights reserved.
Swertfeger, Debi K; Li, Hailong; Rebholz, Sandra; Zhu, Xiaoting; Shah, Amy S; Davidson, W Sean; Lu, Long J
2017-04-01
HDL has been shown to possess a variety of cardio-protective functions, including removal of excess cholesterol from the periphery, and inhibition of lipoprotein oxidation. It has been proposed that various HDL subparticles exist, each with distinct protein and lipid compositions, which may be responsible for HDL's many functions. We hypothesized that HDL functions will co-migrate with the operational lipoprotein subspecies when separated by gel filtration chromatography. Plasma from 10 healthy male donors was fractionated and the protein composition of the phospholipid containing fractions was analyzed by mass spectrometry (MS). Each fraction was evaluated for its proteomic content as well as its ability to promote cholesterol efflux and protect low density lipoprotein (LDL) from free radical oxidation. For each function, several peaks of activity were identified across the plasma size gradient. Neither cholesterol efflux or LDL antioxidation activity correlated strongly with any single protein across the fractions. However, we identified multiple proteins that had strong correlations (r values >0.7, p functional categories, including those traditionally associated with lipid metabolism, as well as alternative complement cascade, innate immunity and clotting cascades and immunoglobulins. Additionally, the phospholipid and cholesterol concentration of the fractions correlated strongly with cholesterol efflux (r = 0.95 and 0.82 respectively), whereas the total protein content of the fractions correlated best with antioxidant activity across all fractions (r = 0.746). Furthermore, two previously postulated subspecies (apoA-I, apoA-II and apoC-1; as well as apoA-I, apoC-I and apoJ) were found to have strong correlations with both cholesterol efflux and antioxidation activity. Up till now, very little has been known about how lipoprotein composition mediates functions like cholesterol efflux and antioxidation. © 2017 by The American Society for Biochemistry and
Voskrebenzev, Andreas; Gutberlet, Marcel; Becker, Lena; Wacker, Frank; Vogel-Claussen, Jens
2016-11-01
To reduce the influence of tidal volume on fractional ventilation (FV) derived by Fourier decomposition (FD). Twelve volunteers were examined on a 1.5 Tesla scanner. Spoiled gradient echo imaging of coronal and sagittal slices of the lung were performed. The tidal volume variations between different acquisitions were studied by reproducibility and repeatability measurements. To adjust the FV derived by FD for tidal volume differences between the measurements, during all acquisitions, the lung volume changes were measured by a spirometer and used to calculate a global FV parameter. As an alternative, using the FD data, the lung area changes were calculated and used for the adjustment. Reproducibility analysis of unadjusted coronal FV showed a determination coefficient of R2 = 71% and an intraclass correlation coefficient of ICC = 93%. Differences in the measurements could be ascribed to different tidal volumes. Area adjusted values exhibited an increased R2 of 84% and a higher ICC of 97%. For the coronal middle slice/sagittal slices in free breathing, the inter-volunteer coefficient of variation was reduced from 0.23/0.28 (unadjusted) to 0.16/0.20 (spirometer) or 0.12/0.13 (area). The calculation of lung area changes is sufficient to increase the reproducibility of FV in a volunteer cohort avoiding the need for an MRI compatible spirometer. Magn Reson Med 76:1542-1550, 2016. © 2015 International Society for Magnetic Resonance in Medicine. © 2015 International Society for Magnetic Resonance in Medicine.
Prediction of gas volume fraction in fully-developed gas-liquid flow in a vertical pipe
Energy Technology Data Exchange (ETDEWEB)
Islam, A.S.M.A.; Adoo, N.A.; Bergstrom, D.J., E-mail: nana.adoo@usask.ca [University of Saskatchewan, Department of Mechanical Engineering, Saskatoon, SK (Canada); Wang, D.F. [Canadian Nuclear Laboratories, Chalk River, ON (Canada)
2015-07-01
An Eulerian-Eulerian two-fluid model has been implemented for the prediction of the gas volume fraction profile in turbulent upward gas-liquid flow in a vertical pipe. The two-fluid transport equations are discretized using the finite volume method and a low Reynolds number κ-ε turbulence model is used to predict the turbulence field for the liquid phase. The contribution to the effective turbulence by the gas phase is modeled by a bubble induced turbulent viscosity. For the fully-developed flow being considered, the gas volume fraction profile is calculated using the radial momentum balance for the bubble phase. The model potentially includes the effect of bubble size on the interphase forces and turbulence model. The results obtained are in good agreement with experimental data from the literature. The one-dimensional formulation being developed allows for the efficient assessment and further development of both turbulence and two-fluid models for multiphase flow applications in the nuclear industry. (author)
Developing Methods for Fraction Cover Estimation Toward Global Mapping of Ecosystem Composition
Roberts, D. A.; Thompson, D. R.; Dennison, P. E.; Green, R. O.; Kokaly, R. F.; Pavlick, R.; Schimel, D.; Stavros, E. N.
2016-12-01
Terrestrial vegetation seldom covers an entire pixel due to spatial mixing at many scales. Estimating the fractional contributions of photosynthetic green vegetation (GV), non-photosynthetic vegetation (NPV), and substrate (soil, rock, etc.) to mixed spectra can significantly improve quantitative remote measurement of terrestrial ecosystems. Traditional methods for estimating fractional vegetation cover rely on vegetation indices that are sensitive to variable substrate brightness, NPV and sun-sensor geometry. Spectral mixture analysis (SMA) is an alternate framework that provides estimates of fractional cover. However, simple SMA, in which the same set of endmembers is used for an entire image, fails to account for natural spectral variability within a cover class. Multiple Endmember Spectral Mixture Analysis (MESMA) is a variant of SMA that allows the number and types of pure spectra to vary on a per-pixel basis, thereby accounting for endmember variability and generating more accurate cover estimates, but at a higher computational cost. Routine generation and delivery of GV, NPV, and substrate (S) fractions using MESMA is currently in development for large, diverse datasets acquired by the Airborne Visible Infrared Imaging Spectrometer (AVIRIS). We present initial results, including our methodology for ensuring consistency and generalizability of fractional cover estimates across a wide range of regions, seasons, and biomes. We also assess uncertainty and provide a strategy for validation. GV, NPV, and S fractions are an important precursor for deriving consistent measurements of ecosystem parameters such as plant stress and mortality, functional trait assessment, disturbance susceptibility and recovery, and biomass and carbon stock assessment. Copyright 2016 California Institute of Technology. All Rights Reserved. We acknowledge support of the US Government, NASA, the Earth Science Division and Terrestrial Ecology program.
Nomura, J-I; Uwano, I; Sasaki, M; Kudo, K; Yamashita, F; Ito, K; Fujiwara, S; Kobayashi, M; Ogasawara, K
2017-10-05
Preoperative hemodynamic impairment in the affected cerebral hemisphere is associated with the development of cerebral hyperperfusion following carotid endarterectomy. Cerebral oxygen extraction fraction images generated from 7T MR quantitative susceptibility mapping correlate with oxygen extraction fraction images on positron-emission tomography. The present study aimed to determine whether preoperative oxygen extraction fraction imaging generated from 7T MR quantitative susceptibility mapping could identify patients at risk for cerebral hyperperfusion following carotid endarterectomy. Seventy-seven patients with unilateral internal carotid artery stenosis (≥70%) underwent preoperative 3D T2*-weighted imaging using a multiple dipole-inversion algorithm with a 7T MR imager. Quantitative susceptibility mapping images were then obtained, and oxygen extraction fraction maps were generated. Quantitative brain perfusion single-photon emission CT was also performed before and immediately after carotid endarterectomy. ROIs were automatically placed in the bilateral middle cerebral artery territories in all images using a 3D stereotactic ROI template, and affected-to-contralateral ratios in the ROIs were calculated on quantitative susceptibility mapping-oxygen extraction fraction images. Ten patients (13%) showed post-carotid endarterectomy hyperperfusion (cerebral blood flow increases of ≥100% compared with preoperative values in the ROIs on brain perfusion SPECT). Multivariate analysis showed that a high quantitative susceptibility mapping-oxygen extraction fraction ratio was significantly associated with the development of post-carotid endarterectomy hyperperfusion (95% confidence interval, 33.5-249.7; P = .002). Sensitivity, specificity, and positive- and negative-predictive values of the quantitative susceptibility mapping-oxygen extraction fraction ratio for the prediction of the development of post-carotid endarterectomy hyperperfusion were 90%, 84%, 45%, and 98
Reflectometric mapping of microregional blood flow and blood volume in the brain cortex.
Eke, A
1982-01-01
A reflectometric indicator-dilution method has been developed for mapping the parenchymal minute volume flow and blood content over tiny superficial areas of the brain cortex at 625 or 2500 locations, respectively. About 0.4 ml dextran-saline solution was used as nondiffusible indicator and injected into the feline cerebral circulation for each measurement. The subsequent cerebrocortical transit of the hemodiluted bolus was detected as a temporary change in the tissue optical density [OD(t)] and interpreted as indicator dilution, C(t). This gave the data necessary to calculate the microregional blood volume (mrCBV), mean transit time of the bolus (mrMTT), and the microregional blood flow (mrCBF = mrCBV/mrMTT). A two-dimensional record of the OD(t) function was made on Kodak SO 115 film by 16-mm cinematography, as a reflectometric tool, over an exposed area of the brain cortex during the bolus perfusion. Later, the microregional OD(t) functions were retrieved for analysis in a square array from the developed film by computer-controlled, frame-by-frame scanning densitometry. Maps of mrCBF, mrCBV, and mrMTT were presented as square arrays of gray-scaled pixels. The maximal spatial and temporal resolution of the method was 0.015 mm2 (mrCBF), 0.004 mm2 (mrCBV), 6 maps/min (mrCBF), and 600 maps/min (mrCBV).
Statistics of the fractional polarisation of extragalactic dusty sources in Planck HFI maps
Bonavera, L.; Gonzalez-Nuevo, J.; De Marco, B.; Argüeso, F.; Toffolatti, L.
2017-01-01
We estimate the average fractional polarisation at 143, 217 and 353 GHz of a sample of 4697 extragalactic dusty sources by applying stacking technique. The sample is selected from the second version of the Planck Catalogue of Compact Sources at 857 GHz, avoiding the region inside the Planck Galactic mask (fsky ~ 60 per cent). We recover values for the mean fractional polarisation at 217 and 353 GHz of (3.10 \\pm 0.75) per cent and (3.65 \\pm 0.66) per cent, respectively, whereas at 143 GHz we g...
Energy Technology Data Exchange (ETDEWEB)
Sayah, N [Thomas Cancer Center, Richmond, VA (United States); Weiss, E [Virginia Commonwealth University, Richmond, Virginia (United States); Watkins, W [University of Virginia, Charlottesville, VA (United States); Siebers, J [University of Virginia Health System, Charlottesville, VA (United States)
2016-06-15
Purpose: To evaluate the dose-mapping error (DME) inherent to conventional dose-mapping algorithms as a function of dose-matrix resolution. Methods: As DME has been reported to be greatest where dose-gradients overlap tissue-density gradients, non-clinical 66 Gy IMRT plans were generated for 11 lung patients with the target edge defined as the maximum 3D density gradient on the 0% (end of inhale) breathing phase. Post-optimization, Beams were copied to 9 breathing phases. Monte Carlo dose computed (with 2*2*2 mm{sup 3} resolution) on all 10 breathing phases was deformably mapped to phase 0% using the Monte Carlo energy-transfer method with congruent mass-mapping (EMCM); an externally implemented tri-linear interpolation method with voxel sub-division; Pinnacle’s internal (tri-linear) method; and a post-processing energy-mass voxel-warping method (dTransform). All methods used the same base displacement-vector-field (or it’s pseudo-inverse as appropriate) for the dose mapping. Mapping was also performed at 4*4*4 mm{sup 3} by merging adjacent dose voxels. Results: Using EMCM as the reference standard, no clinically significant (>1 Gy) DMEs were found for the mean lung dose (MLD), lung V20Gy, or esophagus dose-volume indices, although MLD and V20Gy were statistically different (2*2*2 mm{sup 3}). Pinnacle-to-EMCM target D98% DMEs of 4.4 and 1.2 Gy were observed ( 2*2*2 mm{sup 3}). However dTransform, which like EMCM conserves integral dose, had DME >1 Gy for one case. The root mean square RMS of the DME for the tri-linear-to- EMCM methods was lower for the smaller voxel volume for the tumor 4D-D98%, lung V20Gy, and cord D1%. Conclusion: When tissue gradients overlap with dose gradients, organs-at-risk DME was statistically significant but not clinically significant. Target-D98%-DME was deemed clinically significant for 2/11 patients (2*2*2 mm{sup 3}). Since tri-linear RMS-DME between EMCM and tri-linear was reduced at 2*2*2 mm{sup 3}, use of this resolution is
Energy Technology Data Exchange (ETDEWEB)
Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Hu, Shenyang Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); McGarrah, Eric J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
2016-04-12
The purpose of this document is to provide a theoretical framework for (1) estimating uranium carbide (UC) volume fraction in a final alloy of uranium with 10 weight percent molybdenum (U-10Mo) as a function of final alloy carbon concentration, and (2) estimating effective^{ 235}U enrichment in the U-10Mo matrix after accounting for loss of ^{235}U in forming UC. This report will also serve as a theoretical baseline for effective density of as-cast low-enriched U-10Mo alloy. Therefore, this report will serve as the baseline for quality control of final alloy carbon content
Energy Technology Data Exchange (ETDEWEB)
Johnson, J.
1995-12-31
A preliminary study of a new method for determining respirable mass concentration is described. This method uses a high volume air sampler and subsequent fractionation of the collected mass using a particle sedimentation technique. Side-by-side comparisons of this method with cyclones were made in the field and in the laboratory. There was good agreement among the samplers in the laboratory, but poor agreement in the field. The effect of wind on the samplers` capture efficiencies is the primary hypothesized source of error among the field results. The field test took place at the construction site of a hazardous waste landfill located on the Hanford Reservation.
Hao, Tian
2017-02-22
The Hall effects, especially the integer, fractional and anomalous quantum Hall effects, have been addressed using Eyring's rate process theory and free volume concept. The basic assumptions are that the conduction process is a common rate controlled "reaction" process that can be described with Eyring's absolute rate process theory; the mobility of electrons should be dependent on the free volume available for conduction electrons. The obtained Hall conductivity is clearly quantized as with prefactors related to both the magnetic flux quantum number and the magnetic quantum number via the azimuthal quantum number, with and without an externally applied magnetic field. This article focuses on two dimensional (2D) systems, but the approaches developed in this article can be extended to 3D systems.
Classification of Alzheimer's disease using regional saliency maps from brain MR volumes
Pulido, Andrea; Rueda, Andrea; Romero, Eduardo
2013-02-01
Accurate diagnosis of Alzheimer's disease (AD) from structural Magnetic Resonance (MR) images is difficult due to the complex alteration of patterns in brain anatomy that could indicate the presence or absence of the pathology. Currently, an effective approach that allows to interpret the disease in terms of global and local changes is not available in the clinical practice. In this paper, we propose an approach for classification of brain MR images, based on finding pathology-related patterns through the identification of regional structural changes. The approach combines a probabilistic Latent Semantic Analysis (pLSA) technique, which allows to identify image regions through latent topics inferred from the brain MR slices, with a bottom-up Graph-Based Visual Saliency (GBVS) model, which calculates maps of relevant information per region. Regional saliency maps are finally combined into a single map on each slice, obtaining a master saliency map of each brain volume. The proposed approach includes a one-to-one comparison of the saliency maps which feeds a Support Vector Machine (SVM) classifier, to group test subjects into normal or probable AD subjects. A set of 156 brain MR images from healthy (76) and pathological (80) subjects, splitted into a training set (10 non-demented and 10 demented subjects) and one testing set (136 subjects), was used to evaluate the performance of the proposed approach. Preliminary results show that the proposed method reaches a maximum classification accuracy of 87.21%.
Directory of Open Access Journals (Sweden)
Lunde Ketil
2009-04-01
Full Text Available Abstract Background Recent studies have shown that real-time three-dimensional (3D echocardiography (RT3DE gives more accurate and reproducible left ventricular (LV volume and ejection fraction (EF measurements than traditional two-dimensional methods. A new semi-automated tool (4DLVQ for volume measurements in RT3DE has been developed. We sought to evaluate the accuracy and repeatability of this method compared to a 3D echo standard. Methods LV end-diastolic volumes (EDV, end-systolic volumes (ESV, and EF measured using 4DLVQ were compared with a commercially available semi-automated analysis tool (TomTec 4D LV-Analysis ver. 2.2 in 35 patients. Repeated measurements were performed to investigate inter- and intra-observer variability. Results Average analysis time of the new tool was 141s, significantly shorter than 261s using TomTec (p p = NS, with bias and 95% limits of agreement of 2.1 ± 21 ml, -0.88 ± 17 ml, and 1.6 ± 11% for EDV, ESV, and EF respectively. Intra-observer variability of 4DLVQ vs. TomTec was 7.5 ± 6.2 ml vs. 7.7 ± 7.3 ml for EDV, 5.5 ± 5.6 ml vs. 5.0 ± 5.9 ml for ESV, and 3.0 ± 2.7% vs. 2.1 ± 2.0% for EF (p = NS. The inter-observer variability of 4DLVQ vs. TomTec was 9.0 ± 5.9 ml vs. 17 ± 6.3 ml for EDV (p p p = NS. Conclusion In conclusion, the new analysis tool gives rapid and reproducible measurements of LV volumes and EF, with good agreement compared to another RT3DE volume quantification tool.
Statistics of the fractional polarization of extragalactic dusty sources in Planck HFI maps
Bonavera, L.; González-Nuevo, J.; De Marco, B.; Argüeso, F.; Toffolatti, L.
2017-11-01
We estimate the average fractional polarization at 143, 217 and 353 GHz of a sample of 4697 extragalactic dusty sources by applying stacking technique. The sample is selected from the second version of the Planck Catalogue of Compact Sources at 857 GHz, avoiding the region inside the Planck Galactic mask (fsky ˜ 60 per cent). We recover values for the mean fractional polarization at 217 and 353 GHz of (3.10 ± 0.75) per cent and (3.65 ± 0.66) per cent, respectively, whereas at 143 GHz we give a tentative value of (3.52 ± 2.48) per cent. We discuss the possible origin of the measured polarization, comparing our new estimates with those previously obtained from a sample of radio sources. We test different distribution functions and we conclude that the fractional polarization of dusty sources is well described by a log-normal distribution, as determined in the radio band studies. For this distribution we estimate μ217GHz = 0.3 ± 0.5 [that would correspond to a median fractional polarization of Πmed = (1.3 ± 0.7) per cent] and μ353GHz = 0.7 ± 0.4 (Πmed = (2.0 ± 0.8) per cent), σ217GHz = 1.3 ± 0.2 and σ353GHz = 1.1 ± 0.2. With these values we estimate the source number counts in polarization and the contribution given by these sources to the Cosmic Microwave Background B-mode angular power spectrum at 217, 353, 600 and 800 GHz. We conclude that extragalactic dusty sources might be an important contaminant for the primordial B-mode at frequencies >217 GHz.
Yao, Y; Nguyen, T D; Pandya, S; Zhang, Y; Hurtado Rúa, S; Kovanlikaya, I; Kuceyeski, A; Liu, Z; Wang, Y; Gauthier, S A
2018-02-01
A hyperintense rim on susceptibility in chronic MS lesions is consistent with iron deposition, and the purpose of this study was to quantify iron-related myelin damage within these lesions as compared with those without rim. Forty-six patients had 2 longitudinal quantitative susceptibility mapping with automatic zero reference scans with a mean interval of 28.9 ± 11.4 months. Myelin water fraction mapping by using fast acquisition with spiral trajectory and T2 prep was obtained at the second time point to measure myelin damage. Mixed-effects models were used to assess lesion quantitative susceptibility mapping and myelin water fraction values. Quantitative susceptibility mapping scans were on average 6.8 parts per billion higher in 116 rim-positive lesions compared with 441 rim-negative lesions ( P quantitative susceptibility mapping values of both the rim and core regions ( P Quantitative susceptibility mapping scans and myelin water fraction in rim-positive lesions decreased from rim to core, which is consistent with rim iron deposition. Whole lesion myelin water fractions for rim-positive and rim-negative lesions were 0.055 ± 0.07 and 0.066 ± 0.04, respectively. In the mixed-effects model, rim-positive lesions had on average 0.01 lower myelin water fraction compared with rim-negative lesions ( P quantitative susceptibility mapping scan was negatively associated with follow-up myelin water fraction ( P Quantitative susceptibility mapping rim-positive lesions maintained a hyperintense rim, increased in susceptibility, and had more myelin damage compared with rim-negative lesions. Our results are consistent with the identification of chronic active MS lesions and may provide a target for therapeutic interventions to reduce myelin damage. © 2018 by American Journal of Neuroradiology.
Novel cardiac magnetic resonance biomarkers: native T1 and extracellular volume myocardial mapping
Cannaò, Paola Maria; Altabella, Luisa; Petrini, Marcello; Alì, Marco; Secchi, Francesco; Sardanelli, Francesco
2016-01-01
Cardiac magnetic resonance (CMR) is a non-invasive diagnostic tool playing a key role in the assessment of cardiac morphology and function as well as in tissue characterization. Late gadolinium enhancement is a fundamental CMR technique for detecting focal or regional abnormalities such as scar tissue, replacement fibrosis, or inflammation using qualitative, semi-quantitative, or quantitative methods, but not allowing for evaluating the whole myocardium in the presence of diffuse disease. The novel T1 mapping approach permits a quantitative assessment of the entire myocardium providing a voxel-by-voxel map of native T1 relaxation time, obtained before the intravenous administration of gadolinium-based contrast material. Combining T1 data obtained before and after contrast injection, it is also possible to calculate the voxel-by-voxel extracellular volume (ECV), resulting in another myocardial parametric map. This article describes technical challenges and clinical perspectives of these two novel CMR biomarkers: myocardial native T1 and ECV mapping. PMID:28533719
LOD map--A visual interface for navigating multiresolution volume visualization.
Wang, Chaoli; Shen, Han-Wei
2006-01-01
In multiresolution volume visualization, a visual representation of level-of-detail (LOD) quality is important for us to examine, compare, and validate different LOD selection algorithms. While traditional methods rely on ultimate images for quality measurement, we introduce the LOD map--an alternative representation of LOD quality and a visual interface for navigating multiresolution data exploration. Our measure for LOD quality is based on the formulation of entropy from information theory. The measure takes into account the distortion and contribution of multiresolution data blocks. A LOD map is generated through the mapping of key LOD ingredients to a treemap representation. The ordered treemap layout is used for relative stable update of the LOD map when the view or LOD changes. This visual interface not only indicates the quality of LODs in an intuitive way, but also provides immediate suggestions for possible LOD improvement through visually-striking features. It also allows us to compare different views and perform rendering budget control. A set of interactive techniques is proposed to make the LOD adjustment a simple and easy task. We demonstrate the effectiveness and efficiency of our approach on large scientific and medical data sets.
Energy Technology Data Exchange (ETDEWEB)
Fukami, Tadanori [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Sato, Hidenori [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Wu, Jin [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Lwin, Thet-Thet- [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Yuasa, Tetsuya [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Kawano, Satoru [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Iida, Keiji [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Akatsuka, Takao [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Hontani, Hidekata [Department of Computer Science and Engineering, Nagoya Institute of Technology, Aichi 466-8555 (Japan); Takeda, Tohoru [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Tamura, Masao [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Yokota, Hiroshi [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan)
2007-07-21
Our study aimed to quantitatively evaluate blood flow in the left ventricle (LV) of apical hypertrophic cardiomyopathy (APH) by combining wall thickness obtained from cardiac magnetic resonance imaging (MRI) and myocardial perfusion from single-photon emission computed tomography (SPECT). In this study, we considered paired MRI and myocardial perfusion SPECT from ten patients with APH and ten normals. Myocardial walls were detected using a level set method, and blood flow per unit myocardial volume was calculated using 3D surface-based registration between the MRI and SPECT images. We defined relative blood flow based on the maximum in the whole myocardial region. Accuracies of wall detection and registration were around 2.50 mm and 2.95 mm, respectively. We finally created a bull's-eye map to evaluate wall thickness, blood flow (cardiac perfusion) and blood flow per unit myocardial volume. In patients with APH, their wall thicknesses were over 10 mm. Decreased blood flow per unit myocardial volume was detected in the cardiac apex by calculation using wall thickness from MRI and blood flow from SPECT. The relative unit blood flow of the APH group was 1/7 times that of the normals in the apex. This normalization by myocardial volume distinguishes cases of APH whose SPECT images resemble the distributions of normal cases.
Object Tracking Vision System for Mapping the UCN τ Apparatus Volume
Lumb, Rowan; UCNtau Collaboration
2016-09-01
The UCN τ collaboration has an immediate goal to measure the lifetime of the free neutron to within 0.1%, i.e. about 1 s. The UCN τ apparatus is a magneto-gravitational ``bottle'' system. This system holds low energy, or ultracold, neutrons in the apparatus with the constraint of gravity, and keeps these low energy neutrons from interacting with the bottle via a strong 1 T surface magnetic field created by a bowl-shaped array of permanent magnets. The apparatus is wrapped with energized coils to supply a magnetic field throughout the ''bottle'' volume to prevent depolarization of the neutrons. An object-tracking stereo-vision system will be presented that precisely tracks a Hall probe and allows a mapping of the magnetic field throughout the volume of the UCN τ bottle. The stereo-vision system utilizes two cameras and open source openCV software to track an object's 3-d position in space in real time. The desired resolution is +/-1 mm resolution along each axis. The vision system is being used as part of an even larger system to map the magnetic field of the UCN τ apparatus and expose any possible systematic effects due to field cancellation or low field points which could allow neutrons to depolarize and possibly escape from the apparatus undetected. Tennessee Technological University.
Prediction of the Soil Water Characteristic from Soil Particle Volume Fractions
DEFF Research Database (Denmark)
Naveed, Muhammad; Møldrup, Per; Tuller, Markus
2012-01-01
) for the SWC, derived from readily available soil properties such as texture and bulk density. A total of 46 soils from different horizons at 15 locations across Denmark were used for models evaluation. The Xw-model predicts the volumetric water content as a function of volumetric fines content (organic matter......Modelling water distribution and flow in partially saturated soils requires knowledge of the soil-water characteristic (SWC). However, measurement of the SWC is challenging and time-consuming, and in some cases not feasible. This study introduces two predictive models (Xw-model and Xw*-model...... and clay). It performed reasonably well for the dry-end (above a pF value of 2.0; pF = log(|Ψ|), where Ψ is the matric potential in cm), but did not do as well closer to saturated conditions. The Xw*-model gives the volumetric water content as a function of volumetric content of particle size fractions...
Jadhav, Shital; Powar, Amit; Patil, Sandip; Supare, Ashish; Farane, Bhagwan; Singh, Rajkumar, Dr.
2017-05-01
The present study was performed to investigate the effect of volume fraction of alpha and transformed beta phase on the high-cycle fatigue (HCF) properties of the bimodal titanium Ti6Al4V alloy. The effect of such morphology on mechanical properties was studied using tensile and rotating bending fatigue test as per ASTM standards. Microstructures and fractography of the specimens were studied using optical and scanning electron microscopy (SEM) respectively.Ti6Al4V alloy samples were heat treated to have three distinctive volume fractions of alpha and transformed beta phase. With an increase in quench delay from 30,50 and 70 sec during quenching after solutionizing temperature of 967°C, the volume fraction of alpha was found to be increased from 20% to 67%. Tests on tensile and rotating bending fatigue showed that the specimen with 20% volume fraction of alpha phase exhibited the highest tensile and fatigue strength, however the properties gets deteriorate with increase in volume fraction of alpha.
DEFF Research Database (Denmark)
Poulsen, Stefan Othmar; Voorhees, P.W.; Lauridsen, Erik Mejdal
2013-01-01
-state distributions of grain sizes and topology were determined. It was found that the grain size distributions were in good agreement with experimentally characterized size distributions for solid particles coarsening in a liquid matrix, and that the distributions of the number of faces were in good agreement....../50 and 40/60 were examined. After an initial transient, the number of grains decrease from ∼2600 to ∼500. It was found that the mean grain size of grains of both phases obeyed a power law with an exponent of 3, and the microstructural evolution was found to be controlled by diffusion. Steady...... with the topology of single-phase grain structures as determined by experiment and simulation. The evolution of size and number of faces for the minority and majority phase grains in the 40/60 volume fraction simulation is presented and discussed. Non-constant curvature across some interphase boundaries...
Pillai, S.; Hemmersam, A. G.; Mukhopadhyay, R.; Meyer, R. L.; Moghimi, S. M.; Besenbacher, F.; Kingshott, P.
2009-01-01
Polymer-based nanopatterning on metal surfaces is of increasing importance to a number of applications, including biosensors, bioelectronic devices and medical implants. Here we show that polycrystalline gold surfaces can be functionalized with monocomponent nanoparticle (NP) assemblies by a simple drop deposition method. Ordered 3D hexagonal close-packed structures consisting of 350 nm polystyrene (PS) NPs on hydrophobically modified gold surfaces from solutions of very low volume fraction (phiv = 0.0006) were obtained as a result of capillary force induced self-assembly, whilst 2D self-assembly of PS NPs was generated over large area on hydrophilic gold and TiO2 surfaces by spin coating. Furthermore, we show that when Triton X-100 is added to the PS NP suspending medium longer range ordering is obtained. Our observations may initiate interesting applications in the areas of nanoengineering of metal-based sensors and as a means to design new nanostructures for biocompatible implant surfaces.
Kockova, Radka; Kacer, Petr; Pirk, Jan; Maly, Jiri; Sukupova, Lucie; Sikula, Viktor; Kotrc, Martin; Barciakova, Lucia; Honsova, Eva; Maly, Marek; Kautzner, Josef; Sedmera, David; Penicka, Martin
2016-04-25
The aim of our study was to investigate the relationship between the cardiac magnetic resonance (CMR)-derived native T1 relaxation time and myocardial extracellular volume (ECV) fraction and the extent of diffuse myocardial fibrosis (DMF) on targeted myocardial left ventricular (LV) biopsy. The study population consisted of 40 patients (age 63±8 years, 65% male) undergoing valve and/or ascending aorta surgery for severe aortic stenosis (77.5%), root dilatation (7.5%) or valve regurgitation (15%). The T1 relaxation time was assessed in the basal interventricular septum pre- and 10-min post-contrast administration using the modified Look-Locker Inversion recovery sequence prior to surgery. LV myocardial biopsy specimen was obtained during surgery from the basal interventricular septal segment matched with the T1 mapping assessment. The percentage of myocardial collagen was quantified using picrosirius red staining. The average percentage of myocardial collagen was 22.0±14.8%. Both native T1 relaxation time with cutoff value ≥1,010 ms (sensitivity=90%, specificity=73%, area under the curve=0.82) and ECV with cutoff value ≥0.32 (sensitivity=80%, specificity=90%, area under the curve=0.85) showed high accuracy to identify severe (>30%) DMF. The native T1 relaxation time showed significant correlation with LV mass (Pmarkers of DMF. (Circ J 2016; 80: 1202-1209).
Ouyang, X; Chen, K; Yao, L; Hu, B; Wu, X; Ye, Q; Guo, X
2015-08-20
The prominent morphometric alterations of Alzheimer's disease (AD) occur both in gray matter and in white matter. Multimodal fusion can examine joint information by combining multiple neuroimaging datasets to identify the covariant morphometric alterations in AD in greater detail. In the current study, we conducted a multimodal canonical correlation analysis and joint independent component analysis to identify the covariance patterns of the gray and white matter by fusing structural magnetic resonance imaging and diffusion tensor imaging data of 39 AD patients (23 males and 16 females, mean age: 74.91±8.13years) and 41 normal controls (NCs) (20 males and 21 females, mean age: 73.97±6.34years) derived from the Alzheimer's Disease Neuroimaging Initiative database. The results revealed 25 joint independent components (ICs), of which three joint ICs exhibited strong links between the gray matter volume and the white matter fractional anisotropy (FA) and significant differences between the AD and NC group. The joint IC maps revealed that the simultaneous changes in the gray matter and FA values primarily involved the following areas: (1) the temporal lobe/hippocampus-cingulum, (2) the frontal/cingulate gyrus-corpus callosum, and (3) the temporal/occipital/parietal lobe-corpus callosum/corona radiata. Our findings suggest that gray matter atrophy is associated with reduced white matter fiber integrity in AD and possibly expand the understanding of the neuropathological mechanisms in AD. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.
Wu, L-M; An, D-A L; Yao, Q-Y; Ou, Y-R Z; Lu, Q; Jiang, M; Xu, J-R
2017-10-01
To explore the relationship between extracellular volume (ECV), native T1, and systolic strain in hypertrophic cardiomyopathy (HCM) and hypertensive patients with left ventricular hypertrophy (HTN LVH) with mildly reduced or preserved ejection fraction. T1 mapping was performed in 45 patients with late gadolinium enhancement positive (LGE+) HCM (mean age, 53±6 years), 11 patients with LGE- (LGE-) HCM (mean age, 56±5 years), and 20 patients with HTN LVH (mean age, 55±6 years) on at 3 T magnetic resonance imaging (MRI) using the modified look-locker inversion-recovery (MOLLI) pulse sequence. Mean T1 value, ECV and circumferential strain parameters were determined for each patient. Overall, the HCM patients had higher native T1 values (1242.92±68.94) and ECV (0.31±0.05) in comparison to those of the HTN LVH patients (1197±46.80, 0.27±0.04; p<0.05). In the subgroup analysis, the HCM LGE+ patients had the highest native T1 values among the three groups. The HCM LGE+ patients had higher ECV than the LGE- patients. HCM LGE- patients had higher ECV than HTN LVH patients (p<0.05). Peak systolic circumferential strain and early diastolic strain rates were reduced in the HCM LGE+ patients in comparison to the HCM LGE- and HTN LVH patients (p<0.05). Reduced peak systolic and early diastolic circumferential strain rates were associated with increased levels of ECV and native T1 values among all the patients. HCM LGE+ patients had higher native T1 values, higher ECV, and an associated reduction in early diastolic strain rates and peak systolic circumferential strains when compared to the HCM LGE- and HTN LVH patients with mildly reduced or preserved ejection fraction. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Singh, Anvesha; Horsfield, Mark A; Bekele, Soliana; Khan, Jamal N; Greiser, Andreas; McCann, Gerry P
2015-07-01
(i) To establish the test-retest reproducibility of myocardial T1 and extracellular volume (ECV) fraction measurement in asymptomatic patients with moderate-severe aortic stenosis (AS), (ii) to compare reproducibility using motion-corrected (MOCO) parametric T1 maps for analysis vs. full MOLLI series of images, and (iii) to compare T1 and ECV between patients and age-matched controls. 3 T cardiac MRI was performed twice on 10 patients (median interval 7 days) to assess reproducibility. An additional 40 patients and 22 asymptomatic controls underwent a single MRI. Native T1 and ECV were calculated by outlining the myocardium on T1 maps generated inline, and using an offline T1 fit on the MOCO multiple inversion-time raw image series, in the reproducibility cohort (n = 10). Reproducibility was excellent using the inline T1 maps (CoVs for T1: 1.77%; ECV: 6.52%) and good using the full MOLLI series (CoVs for T1: 8.52%; ECV: 12.98%). On comparing AS and controls, who were well matched for age, gender and co-morbidities, there was no significant difference in the native T1 or ECV (T1 = 1103.32 ± 33.07 vs. 1092.27 ± 34.29; ECV = 0.243 ± 0.019 vs. 0.251 ± 0.026 in patients and controls, P > 0.05), which was maintained even after splitting the patients into moderate and severe AS subgroups. The test-retest reproducibility of myocardial T1 quantification using MOLLI is excellent in patients with AS and is highest using inline generated T1 maps for analysis. There was no difference in native myocardial T1 or ECV between asymptomatic patients with moderate-severe AS and age-matched controls without valve disease. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.
Neilan, Tomas G; Coelho-Filho, Otavio R; Shah, Ravi V; Abbasi, Siddique A; Heydari, Bobak; Watanabe, Eri; Chen, Yucheng; Mandry, Damien; Pierre-Mongeon, Francois; Blankstein, Ron; Kwong, Raymond Y; Jerosch-Herold, Michael
2013-06-01
This study aimed to test the characteristics of the myocardial extracellular volume fraction (ECV) derived from pre- and post-contrast T1 measurements among healthy volunteers. Cardiac magnetic resonance (CMR) T1 measurements of myocardium and blood before and after contrast allow quantification of the ECV, a tissue parameter that has been shown to change in proportion to the connective tissue fraction. Healthy volunteers underwent standard CMR imaging with administration of gadolinium. T1 measurements were performed with a Look-Locker sequence followed by gradient-echo acquisition. We tested the segmental, interslice, inter-, intra-, and test-retest characteristics of the ECV, as well as the association of the ECV with other variables. Juvenile and aged mice underwent a similar protocol, and cardiac sections were harvested for measurement of fibrosis. In healthy volunteers (N = 32, 56% female; age 21 to 72 years), the ECV averaged 0.28 ± 0.03 (range 0.23 to 0.33). The intraclass coefficients for the intraobserver, interobserver, and test-retest absolute agreements of the ECV were 0.94 (95% confidence interval: 0.84 to 0.98), 0.93 (95% confidence interval: 0.80 to 0.98), and 0.95 (95% confidence interval: 0.52 to 0.99), respectively. In volunteers, the ECV was associated with age (r = 0.74, p volunteers, the myocardial ECV ranges from 0.23 to 0.33, has acceptable test characteristics, and is associated with age, left atrial volume, and left ventricular mass. In mice, the ECV also increases with age and strongly correlates with the extent of myocardial fibrosis. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Neilan, Tomas G.; Coelho-Filho, Otavio R.; Shah, Ravi V.; Abbasi, Siddique A.; Heydari, Bobak; Watanabe, Eri; Chen, Yucheng; Mandry, Damien; Pierre-Mongeon, Francois; Blankstein, Ron; Kwong, Raymond; Jerosch-Herold, Michael
2013-01-01
Objectives We aimed to test the characteristics of the myocardial extracellular volume (ECV) fraction derived from pre and post-contrast T1 measurements among healthy volunteers. Background Cardiac magnetic resonance (CMR) T1 measurements of myocardium and blood before and after contrast allow quantification of the ECV, a tissue parameter that has been shown to change in proportion to the connective tissue fraction. Methods Healthy volunteers underwent a standard CMR with administration of gadolinium. T1 measurements were performed with a Look-Locker sequence followed by gradient-echo acquisition. We tested the segmental, inter-slice, inter-, intra-, and test-retest characteristics of the ECV, as well as the association of the ECV with other variables. Juvenile and aged mice underwent a similar protocol and cardiac sections were harvested for measurement of fibrosis. Results In healthy volunteers (n=32, 56% female; ages 21 to 72), the ECV averaged 0.28 ± 0.03 (range 0.23 to 0.33). The intra-class coefficients for the intra-observer, inter-observer, and test-retest absolute agreements of the ECV were 0.94 (95% confidence interval, 0.84 to 0.98), 0.93 (95% confidence interval, 0.80 to 0.98), and 0.95 (95% confidence interval, 0.52 to 0.99), respectively. In volunteers, the ECV was associated with age (r=0.74, pvolunteers, the myocardial ECV ranges from 0.23 to 0.33, has acceptable test characteristics, and is associated with age, LA volume, and LV mass. In mice, the ECV also increases with age and strongly correlates with the extent of myocardial fibrosis. PMID:23643283
Spathis, G.; Kontou, E.
2017-11-01
In the present work, the nonlinear viscoelastic/viscoplastic response of polymeric materials is described by introducing essential modifications on a model developed in previous works. A constitutive equation of viscoelasticity, based on the transient network theory, is introduced in a more generalized form, which takes into account volume changes during deformation. This time-dependent equation accounts for the nonlinearity and viscoplasticity at small elastic and finite plastic strain regime. The present description was proved to be more flexible, given that it contains a relaxation function that has been derived by considering instead of first order kinetics a fractional derivative that controls the rate of molecular chain detachment from their junctions. Therefore, the new equation has a more global character, appropriate for cases where heavy tails are expected. On the basis of the distributed nature of free volume, a new functional form of the rate of plastic deformation is developed, which is combined with a proper kinematic formulation and leads to the separation of the total strain into the elastic and plastic part. A three-dimensional constitutive equation is then derived for an isotropic, compressible medium. This analysis was proved to be capable of capturing the main aspects of inelastic response as well as the instability stage taking place at the tertiary creep, related to the creep failure.
Directory of Open Access Journals (Sweden)
Bas Versluis
Full Text Available OBJECTIVES: The aim of the current study was to describe a method that assesses the hyperemic microvascular blood plasma volume of the calf musculature. The reversibly albumin binding contrast agent gadofosveset was used in dynamic contrast-enhanced magnetic resonance imaging (DCE MRI to assess the microvascular status in patients with peripheral arterial disease (PAD and healthy controls. In addition, the reproducibility of this method in healthy controls was determined. MATERIALS AND METHODS: Ten PAD patients with intermittent claudication and 10 healthy control subjects were included. Patients underwent contrast-enhanced MR angiography of the peripheral arteries, followed by one DCE MRI examination of the musculature of the calf. Healthy control subjects were examined twice on different days to determine normative values and the interreader and interscan reproducibility of the technique. The MRI protocol comprised dynamic imaging of contrast agent wash-in under reactive hyperemia conditions of the calf musculature. Using pharmacokinetic modeling the hyperemic fractional microvascular blood plasma volume (V(p, unit: % of the anterior tibial, gastrocnemius and soleus muscles was calculated. RESULTS: V(p was significantly lower for all muscle groups in PAD patients (4.3±1.6%, 5.0±3.3% and 6.1±3.6% for anterior tibial, gastrocnemius and soleus muscles, respectively compared to healthy control subjects (9.1±2.0%, 8.9±1.9% and 9.3±2.1%. Differences in V(p between muscle groups were not significant. The coefficient of variation of V(p varied from 10-14% and 11-16% at interscan and interreader level, respectively. CONCLUSIONS: Using DCE MRI after contrast-enhanced MR angiography with gadofosveset enables reproducible assessment of hyperemic fractional microvascular blood plasma volume of the calf musculature. V(p was lower in PAD patients than in healthy controls, which reflects a promising functional (hemodynamic biomarker for the
Raucci, Frank J; Parra, David A; Christensen, Jason T; Hernandez, Lazaro E; Markham, Larry W; Xu, Meng; Slaughter, James C; Soslow, Jonathan H
2017-08-02
Extracellular volume fraction (ECV) is altered in pathological cardiac remodeling and predicts death and arrhythmia. ECV can be quantified using cardiovascular magnetic resonance (CMR) T1 mapping but calculation requires a measured hematocrit (Hct). The longitudinal relaxation of blood has been used in adults to generate a synthetic Hct (estimate of true Hct) but has not been validated in pediatric populations. One hundred fourteen children and young adults underwent a total of 163 CMRs with T1 mapping. The majority of subjects had a measured Hct the same day (N = 146). Native and post-contrast T1 were determined in blood pool, septum, and free wall of mid-LV, avoiding areas of late gadolinium enhancement. Synthetic Hct and ECV were calculated and intraclass correlation coefficient (ICC) and linear regression were used to compare measured and synthetic values. The mean age was 16.4 ± 6.4 years and mean left ventricular ejection fraction was 59% ± 9%. The mean measured Hct was 41.8 ± 3.0% compared to the mean synthetic Hct of 43.2% ± 2.9% (p ECV was 30.5% ± 4.8% and mean synthetic mid-free wall ECV of local model was 29.7% ± 4.6% (p ECV ranged from -8.4% to 4.3% in the septum and -12.6% to 15.8% in the free wall. Using our laboratory's normal cut-off of 28.5%, 59 patients (37%) were miscategorized (53 false negatives, 6 false positives) with published model ECV. The local model had 37 miscategorizations (20 false negatives, 17 false positives), significantly fewer but still a substantial number (23%). Our data suggest that use of synthetic Hct for the calculation of ECV results in miscategorization of individual patients. This difference may be less significant once synthetic ECV is calculated and averaged over a large research cohort, making it potentially useful as a research tool. However, we recommend formal measurement of Hct in children and young adults for clinical CMRs.
Hanafee, Z. M.; Khalina, A.; Norkhairunnisa, M.; Syams, Z. Edi; Liew, K. E.
2017-09-01
This paper investigates the effect of fibre volume fraction on mechanical properties of banana-pineapple leaf (PaLF)-glass reinforced epoxy resin under tensile loading. Uniaxial tensile tests were carried out on specimens with different fibre contents (30%, 40%, 50% in weight). The composite specimens consists of 13 different combinations. The effect of hybridisation between synthetic and natural fibre onto tensile properties was determined and the optimum fibre volume fraction was obtained at 50% for both banana and PaLF composites. Additional 1 layer of woven glass fibre increased the tensile strength of banana-PaLF composite up to 85%.
Kim, P.; Choi, Y.; Ghim, Y. S.
2016-12-01
Both sunphotometer (Cimel, CE-318) and skyradiometer (Prede, POM-02) were operated in May, 2015 as a part of the Megacity Air Pollution Studies-Seoul (MAPS-Seoul) campaign. These instruments were collocated at the Hankuk University of Foreign Studies (Hankuk_UFS) site of AErosol RObotic NETwork (AERONET) and the Yongin (YGN) site of SKYradiometer NETwork (SKYNET). The aerosol volume size distribution at the surface was measured using a wide range aerosol spectrometer (WRAS) system consisting of a scanning mobility particle sizer (Grimm, Model 5.416; 45 bins, 0.01-1.09 μm) and an optical particle counter (Grimm, Model 1.109; 31 bins, 0.27-34 μm). The measurement site (37.34oN, 127.27oE, 167 m above sea level) is located about 35 km southeast of downtown Seoul. To investigate the discrepancies in volume concentrations, effective diameters and fine mode volume fractions, we compared the volume size distributions from sunphotometer, skyradiometer, and WRAS system when the measurement time coincided within 5 minutes considering that the measurement intervals were different between instruments.
Directory of Open Access Journals (Sweden)
M. S. Adams
2016-06-01
Full Text Available Debris flows cause an average € 30 million damages and 1-2 fatalities every year in Austria. Detailed documentation of their extent and magnitude is essential for understanding, preventing and mitigating these natural hazard events. The recent development of unmanned aerial systems (UAS has provided a new possibility for on-demand high-resolution monitoring and mapping. Here, we present a study, where the spatial extent and volume of a large debris flow event were mapped with different UAS, fitted with commercial off-the-shelf sensors. Orthophotos and digital terrain models (DTM were calculated using structure-from-motion photogrammetry software. Terrain height differences caused by the debris flow in the catchment and valley floor were derived by subtracting the pre-event airborne laser scanning (ALS DTM from a post-event UAS-DTM. The analysis of the volumetric sediment budget showed, that approximately 265,000 m³ material was mobilised in the catchment, of which 45,000 m³ settled there; of the material, which reached the valley floor, 120,000 m³ was deposited, while another 10,000 m³ was eroded from there. The UAS-results were validated against ALS data and imagery from a traditional manned-aircraft photogrammetry campaign. In conclusion, the UAS-data can reach an accuracy and precision comparable to manned aircraft data, but with the added benefits of higher flexibility, easier repeatability, less operational constraints and higher spatial resolution.
Meng, Yiqing; Lucas, Gary P.
2017-05-01
This paper presents the design and implementation of an inductive flow tomography (IFT) system, employing a multi-electrode electromagnetic flow meter (EMFM) and novel reconstruction techniques, for measuring the local water velocity distribution in water continuous single and multiphase flows. A series of experiments were carried out in vertical-upward and upward-inclined single phase water flows and ‘water continuous’ gas-water and oil-gas-water flows in which the velocity profiles ranged from axisymmetric (single phase and vertical-upward multiphase flows) to highly asymmetric (upward-inclined multiphase flows). Using potential difference measurements obtained from the electrode array of the EMFM, local axial velocity distributions of the continuous water phase were reconstructed using two different IFT reconstruction algorithms denoted RT#1, which assumes that the overall water velocity profile comprises the sum of a series of polynomial velocity components, and RT#2, which is similar to RT#1 but which assumes that the zero’th order velocity component may be replaced by an axisymmetric ‘power law’ velocity distribution. During each experiment, measurement of the local water volume fraction distribution was also made using the well-established technique of electrical resistance tomography (ERT). By integrating the product of the local axial water velocity and the local water volume fraction in the cross section an estimate of the water volumetric flow rate was made which was compared with a reference measurement of the water volumetric flow rate. In vertical upward flows RT#2 was found to give rise to water velocity profiles which are consistent with the previous literature although the profiles obtained in the multiphase flows had relatively higher central velocity peaks than was observed for the single phase profiles. This observation was almost certainly a result of the transfer of axial momentum from the less dense dispersed phases to the water
Zare, Ehsan; Huang, Jingyi; Triantafilis, John
2017-04-01
Together the three particle size fractions (PSFs) of clay, silt, and sand are the most fundamental soil properties because of their relative abundance influences the physical, chemical and biological activities in soil. Therefore, there is an increasing need for high-resolution information on spatial distribution of soil texture. Unfortunately, determining PSFs requires a laboratory method which is time-consuming. One way to add value is to use digital soil mapping. Specifically, using mathematical models, such as multiple linear regression (MLR), to couple ancillary data to PSF data. However, this approach does not account for the special requirements of compositional data. Here we demonstrated how ancillary data can be coupled via MLR modelling to an additive log-ratio transformation (ALR) of the PSF to meet these requirements. We compared these two approaches (MLR vs. ALR-MLR). We also compared the use of different ancillary data including proximally sensed gamma-ray spectrometry (i.e. RS700), electromagnetic induction (i.e. DUALEM-421S) and elevation data. In addition, we tested how prediction might be improved by using ancillary data measured on transects (which simulated measurements made on 6.5 m transects) as compared to interpolation from transects spaced 13 m and 26 m apart. Although the ALR-MLR approach did not produce significantly better results, it generated predicted soil PSFs which summed to 100. We found that for predicting PSFs at various depths, all ancillary data was useful with elevation and gamma-ray slightly better for topsoil and elevation and EM data better for subsoil prediction. In addition, a reduced transect spacing (26 m) and sampling size (9-16) can be adopted for mapping soil PSFs and soil texture across the study field.
Automatic Estimation of Excavation Volume from Laser Mobile Mapping Data for Mountain Road Widening
Directory of Open Access Journals (Sweden)
Massimo Menenti
2013-09-01
Full Text Available Roads play an indispensable role as part of the infrastructure of society. In recent years, society has witnessed the rapid development of laser mobile mapping systems (LMMS which, at high measurement rates, acquire dense and accurate point cloud data. This paper presents a way to automatically estimate the required excavation volume when widening a road from point cloud data acquired by an LMMS. Firstly, the input point cloud is down-sampled to a uniform grid and outliers are removed. For each of the resulting grid points, both on and off the road, the local surface normal and 2D slope are estimated. Normals and slopes are consecutively used to separate road from off-road points which enables the estimation of the road centerline and road boundaries. In the final step, the left and right side of the road points are sliced in 1-m slices up to a distance of 4 m, perpendicular to the roadside. Determining and summing each sliced volume enables the estimation of the required excavation for a widening of the road on the left or on the right side. The procedure, including a quality analysis, is demonstrated on a stretch of a mountain road that is approximately 132 m long as sampled by a Lynx LMMS. The results in this particular case show that the required excavation volume on the left side is 8% more than that on the right side. In addition, the error in the results is assessed in two ways. First, by adding up estimated local errors, and second, by comparing results from two different datasets sampling the same piece of road both acquired by the Lynx LMMS. Results of both approaches indicate that the error in the estimated volume is below 4%. The proposed method is relatively easy to implement and runs smoothly on a desktop PC. The whole workflow of the LMMS data acquisition and subsequent volume computation can be completed in one or two days and provides road engineers with much more detail than traditional single-point surveying methods such as
Directory of Open Access Journals (Sweden)
Panagiotis Lagouvardos
2015-01-01
Full Text Available Background: Volume fraction (Vf and location of internal voids and gaps in relation to material type and cavity dimensions in ultraconservative restorations were investigated in this study. Materials and Methods: Forty-eight round cavities of 1.3 mm mean diameter and 2.6 mm mean depth were made on buccal and lingual surfaces of recently extracted human teeth. These were filled and thermocycled with two low viscosity composites (AeliteFlo LV [AF], PermaFlo [PF], one high viscosity composite (Aelite aesthetic enamel [AA] and one glass-ionomer (GCFuji IX GP. X-ray microtomography, following a specific procedure, was applied to all cavities before and after their restoration, using SkyScan-1072 microtomographer. Vf percent (Vf% and location of voids and gaps were recorded and analysed statistically at a = 0.05. Kruskal-Wallis nonparametric analysis of variance, post-hoc analysis, Mann-Whitney test, Spearman′s correlation analysis were used to analyze data. Results: Cavities filled with AF and PF showed significantly lower V f % of voids and gaps than all other restorations (P 0.05. The proportion of cavities with gaps at the bottom and side walls was lower in those filled with AF and PF (P < 0.05. Conclusion: Cavities filled with low viscosity composites presented the lowest amount of internal voids and gaps. Glass-ionomer and high viscosity composite restorative materials showed the highest amount of interfacial gaps. Only in the high viscosity composite restorations the amount of voids and gaps correlated with the cavity depth, width and volume.
Future use of tritium in mapping pre-bomb groundwater volumes.
Eastoe, C J; Watts, C J; Ploughe, M; Wright, W E
2012-01-01
The tritium input to groundwater, represented as volume-weighted mean tritium concentrations in precipitation, has been close to constant in Tucson and Albuquerque since 1992, and the decrease in tritium concentrations at the tail end of the bomb tritium pulse has ceased. To determine the future usefulness of tritium measurements in southwestern North America, volume-weighted mean tritium levels in seasonal aggregate precipitation samples have been gathered from 26 sites. The averages range from 2 to 9 tritium units (TU). Tritium concentrations increase with site latitude, and possibly with distance from the coast and with site altitude, reflecting local ratios of combination of low-tritium moisture advected from the oceans with high-tritium moisture originating near the tropopause. Tritium used alone as a tool for mapping aquifer volumes containing only pre-bomb recharge to groundwater will become ambiguous when the tritium in precipitation at the end of the bomb tritium pulse decays to levels close to the analytical detection limit. At such a time, tritium in precipitation from the last one to two decades of the bomb pulse will become indistinguishable from pre-bomb recharge. The threshold of ambiguity has already arrived in coastal areas with a mean of 2 TU in precipitation and will follow in the next three decades throughout the study region. Where the mean tritium level is near 5 TU, the threshold will occur between 2025 and 2030, given a detection limit of 0.6 TU. Similar thresholds of ambiguity, with different local timing possible, apply globally. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.
Directory of Open Access Journals (Sweden)
Dańko R.
2016-12-01
Full Text Available The aim of the hereby paper is to present the developed model of determining the volume and surface porosity based on the main fraction of polifractional materials, its experimental verification and utilisation for the interpretation of effects accompanying the formation of a moulding sand apparent density, porosity and permeability in the blowing processes of the core and moulds technology.
Gholipour Peyvandi, R.; Islami Rad, S. Z.
2017-12-01
The determination of the volume fraction percentage of the different phases flowing in vessels using transmission gamma rays is a conventional method in petroleum and oil industries. In some cases, with access only to the one side of the vessels, attention was drawn toward backscattered gamma rays as a desirable choice. In this research, the volume fraction percentage was measured precisely in water-gasoil-air three-phase flows by using the backscatter gamma ray technique andthe multilayer perceptron (MLP) neural network. The volume fraction determination in three-phase flows requires two gamma radioactive sources or a dual-energy source (with different energies) while in this study, we used just a 137Cs source (with the single energy) and a NaI detector to analyze backscattered gamma rays. The experimental set-up provides the required data for training and testing the network. Using the presented method, the volume fraction was predicted with a mean relative error percentage less than 6.47%. Also, the root mean square error was calculated as 1.60. The presented set-up is applicable in some industries with limited access. Also, using this technique, the cost, radiation safety and shielding requirements are minimized toward the other proposed methods.
Directory of Open Access Journals (Sweden)
Sascha Nink
2015-09-01
Full Text Available The availability of accurate and timely information on timber volume is important for supporting operational forest management. One option is to combine statistical concepts (e.g., small area estimates with specifically designed terrestrial sampling strategies to provide estimations also on the level of administrative units such as forest districts. This may suffice for economic assessments, but still fails to provide spatially explicit information on the distribution of timber volume within these management units. This type of information, however, is needed for decision-makers to design and implement appropriate management operations. The German federal state of Rhineland-Palatinate is currently implementing an object-oriented database that will also allow the direct integration of Earth observation data products. This work analyzes the suitability of forthcoming multi- and hyperspectral satellite imaging systems for producing local distribution maps for timber volume of Norway spruce, one of the most economically important tree species. In combination with site-specific inventory data, fully processed hyperspectral data sets (HyMap were used to simulate datasets of the forthcoming EnMAP and Sentinel-2 systems to establish adequate models for estimating timber volume maps. The analysis included PLS regression and the k-NN method. Root Mean Square Errors between 21.6% and 26.5% were obtained, where k-NN performed slightly better than PLSR. It was concluded that the datasets of both simulated sensor systems fulfill accuracy requirements to support local forest management operations and could be used in synergy. Sentinel-2 can provide meaningful volume distribution maps in higher geometric resolution, while EnMAP, due to its hyperspectral coverage, can contribute complementary information, e.g., on biophysical conditions.
Energy Technology Data Exchange (ETDEWEB)
Wang, Shuli; Li, Jinghui; Chen, Xiuyu; Yin, Gang; Lan, Tian; Dai, Linlin; Zhang, Yan; Yin, Xiaorong; Zhao, Shihua [Chinese Academy of Medical Sciences and Peking Union Medical College, Department of Magnetic Resonance Imaging, Cardiovascular Imaging and Intervention Center, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Beijing (China); Hu, Hongjie [Zhejiang University, Department of Radiology, Sir Run Run Shaw Hospital, School of Medicine, Hangzhou (China); Lu, Minjie [Chinese Academy of Medical Sciences and Peking Union Medical College, Department of Magnetic Resonance Imaging, Cardiovascular Imaging and Intervention Center, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Beijing (China); Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Department of Health and Human Services, Bethesda, MD (United States); Sirajuddin, Arlene; Arai, Andrew E. [Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Department of Health and Human Services, Bethesda, MD (United States); An, Jing [Siemens Shenzhen Magnetic Resonance Ltd., Siemens MRI Center, Shenzhen, Guangdong (China); Song, Lei; Dang, Aimin [Chinese Academy of Medical Sciences and Peking Union Medical College, Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Beijing (China); Kellman, Peter [National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), US Department of Health and Human Services, Cardiovascular and Pulmonary Branch, Bethesda, MD (United States)
2017-11-15
To determine whether extracellular volume fraction (ECV) quantification by cardiac magnetic resonance (CMR) can demonstrate left ventricle (LV) abnormalities and relationship between ECV and LV remodeling in hypertension (HTN) patients ECV quantification was prospectively performed in 134 consecutive HTN patients and 97 healthy subjects. Individual and regional ECV were compared to the regions on late gadolinium enhancement (LGE) images. Statistical analysis of the relationship between LV global functional parameters and ECV was carried out using Pearson's correlation, Student's t test and multiple regressions. In the HTN group, 70.1% (94/134) were LGE negative and 29.9% (40/134) LGE positive. The mean ECV after adjusting for age, sex, BMI, diabetes, smoking and dyslipidaemia in healthy controls and LGE-negative patients were 26.9 ± 2.67% and 28.5 ± 2.9% (p < 0.001), respectively. The differences in ECV reached statistical significance among the regions of LGE, LGE-Peri, LGE remote and the normal area between the control and LGE-positive subgroup (all p < 0.05). Global ECV significantly correlated with LVEF (r = -0.466, p < 0.001) and LV hypertrophy (r = 0.667, p < 0.001). ECV can identify LV abnormalities at an early stage in HTN patients without LGE. These abnormalities may reflect an increase in diffuse myocardial fibrosis and are associated with LV remodeling. (orig.)
Directory of Open Access Journals (Sweden)
Ming Kun Yew
2015-01-01
Full Text Available This paper presents the effects of low volume fraction (Vf of polyvinyl alcohol (PVA fibers on the mechanical properties of oil palm shell (OPS high strength lightweight concrete mixtures. The slump, density, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity under various curing conditions have been measured and evaluated. The results indicate that an increase in PVA fibers decreases the workability of the concrete and decreases the density slightly. The 28-day compressive strength of oil palm shell fiber-reinforced concrete (OPSFRC high strength lightweight concrete (HSLWC subject to continuous moist curing was within the range of 43–49 MPa. The average modulus of elasticity (E value is found to be 16.1 GPa for all mixes, which is higher than that reported in previous studies and is within the range of normal weight concrete. Hence, the findings of this study revealed that the PVA fibers can be used as an alternative material to enhance the properties of OPS HSLWC for building and construction applications.
Effect of CNT volume fraction on wear properties of hybrid CNT+SiCsf/AS52 Mg matrix composites
Lee, Byoung Woo; Cho, Dae Hyun; Nam, Ji Hoon; Park, Ik Min
2016-07-01
The effect of the carbon nanotube (CNT) volume fraction on the wear properties of hybrid Mg composites was investigated. The hybrid x vol% CNT + 15 vol% SiCsf-reinforced Mg-5Al-2Si alloy (AS52) matrix composites (x=0, 5 and 10 vol%) were fabricated in two steps involving preform fabrication and squeeze infiltration. The wear rate of the hybrid CNT+SiCsf/AS52 Mg metal matrix composites (MMCs) was evaluated using ballon-disk wear testing, and the roughness was measured using confocal laser 3D microscopy. Additionally, the worn surfaces were examined using high-resolution transmission electron microscopy. The adhesive wear and worn surface roughness of the hybrid CNT+SiCsf/AS52 Mg MMCs were reduced with increasing CNT addition. The CNTs hindered pull-out or cracking of the SiCsfs and matrix deformation. The wear resistance of the hybrid CNT+SiCsf/AS52 Mg MMCs was improved by the CNT additions, causing self-lubricant and strengthening effects compared with the single SiCsf/AS52 Mg MMCs.
Jamil, Norazaliza Mohd; Wang, Qi
2017-09-01
Renewable energy or biofuel from lignocellulosic biomass is an alternative way to replace the depleting fossil fuels. The production cost can be reduced by increasing the concentration of biomass particles. However, lignocellulosic biomass is a suspension of natural fibres, and processing at high solid concentration is a challenging task. Thus, understanding the factors that affect the rheology of biomass suspension is crucial in order to maximize the production at a minimum cost. Our aim was to develop a mathematical model for enzymatic hydrolysis of cellulose by combining three scales: the macroscopic flow field, the mesoscopic particle orientation, and the microscopic reactive kinetics. The governing equations for the flow field, particle stress, kinetic equations, and particle orientation were coupled and were simultaneously solved using a finite element method based software, COMSOL. One of the main results was the changes in rheology of biomass suspension were not only due to the decrease in volume fraction of particles, but also due the types of fibres. The results from the simulation model agreed qualitatively with the experimental findings. This approach has enables us to obtain better predictive capabilities, hence increasing our understanding on the behaviour of biomass suspension.
DEFF Research Database (Denmark)
Haarmark, Christian; Haase, Christine; Jensen, Maria Maj
2016-01-01
age and both left and right ventricular volumes in women (r = -0.4, P right end systolic ventricular volume in men (r = -0.3, P = .001). CONCLUSION: A set of reference values for cardiac evaluation prior to chemotherapy in cancer patients without other known cardiopulmonary......BACKGROUND: Estimation of left ventricular ejection fraction (LVEF) using equilibrium radionuclide angiography is an established method for assessment of left ventricular function. The purpose of this study was to establish normative data on left and right ventricular volumes and ejection fraction......, using cadmium-zinc-telluride SPECT camera. METHODS AND RESULTS: From routine assessments of left ventricular function in 1172 patients, we included 463 subjects (194 men and 269 women) without diabetes, previous potentially cardiotoxic chemotherapy, known cardiovascular or pulmonary disease. The lower...
National Oceanic and Atmospheric Administration, Department of Commerce — This data set comprises the Environmental Sensitivity Index (ESI) maps in Portable Document Format (.PDF) for the shoreline of East Florida (to encompass the coastal...
Wang, Shuli; Hu, Hongjie; Lu, Minjie; Sirajuddin, Arlene; Li, Jinghui; An, Jing; Chen, Xiuyu; Yin, Gang; Lan, Tian; Dai, Linlin; Zhang, Yan; Yin, Xiaorong; Song, Lei; Dang, Aimin; Kellman, Peter; Arai, Andrew E; Zhao, Shihua
2017-04-24
To determine whether extracellular volume fraction (ECV) quantification by cardiac magnetic resonance (CMR) can demonstrate left ventricle (LV) abnormalities and relationship between ECV and LV remodeling in hypertension (HTN) patients METHODS: ECV quantification was prospectively performed in 134 consecutive HTN patients and 97 healthy subjects. Individual and regional ECV were compared to the regions on late gadolinium enhancement (LGE) images. Statistical analysis of the relationship between LV global functional parameters and ECV was carried out using Pearson's correlation, Student's t test and multiple regressions. In the HTN group, 70.1% (94/134) were LGE negative and 29.9% (40/134) LGE positive. The mean ECV after adjusting for age, sex, BMI, diabetes, smoking and dyslipidaemia in healthy controls and LGE-negative patients were 26.9 ± 2.67% and 28.5 ± 2.9% (p ECV reached statistical significance among the regions of LGE, LGE-Peri, LGE remote and the normal area between the control and LGE-positive subgroup (all p ECV significantly correlated with LVEF (r = -0.466, p ECV can identify LV abnormalities at an early stage in HTN patients without LGE. These abnormalities may reflect an increase in diffuse myocardial fibrosis and are associated with LV remodeling. • Diffuse myocardial fibrosis may develop in hypertensive cardiomyopathy before conventional MRI detectable LGE. • ECV can identify myocardial fibrosis at an early stage in hypertensive patients. • Elevated ECV is associated with decreased LV global function and LV remodeling in hypertension.
DEFF Research Database (Denmark)
Svarer, Claus; Madsen, Karina; Hasselbalch, Steen G.
2005-01-01
The purpose of this study was to develop and validate an observer-independent approach for automatic generation of volume-of-interest (VOI) brain templates to be used in emission tomography studies of the brain. The method utilizes a VOI probability map created on the basis of a database of several...... delineation of the VOI set. The approach was also shown to work equally well in individuals with pronounced cerebral atrophy. Probability-map-based automatic delineation of VOIs is a fast, objective, reproducible, and safe way to assess regional brain values from PET or SPECT scans. In addition, the method...
Ye, Fangxia; Hojamberdiev, Mirabbos; Xu, Yunhua; Zhong, Lisheng; Yan, Honghua; Chen, Zhe
2014-04-01
The V8C7 particulates-reinforced iron-based metal matrix composite with 8-33 vol.% V8C7 was produced by infiltration casting process with subsequent heat treatment at 1164 °C for 3 h. With increasing the volume fraction of V8C7 in the composite, microhardness of the composite increases, while its impact toughness decreases. Relative wear resistance of the composite with different volume fractions of V8C7 was also investigated in this study. The composite with 24 vol.% V8C7 shows the highest relative wear resistance, which is much higher than that of gray cast iron. Microcracking, microploughing, and the fragmentation of particulates are found to be the dominant wear mechanisms.
Wear Behavior of Al-Mg2Si Cast In-situ Composite: Effect of Mg2Si Different Volume Fractions
Ghiasinejad, J.; Emamy, M.; Ghorbani, M. R.; Malekan, A.
2010-06-01
Al-Mg2Si in situ composites are great candidates for automobile brake discs due to their low density, reasonably high young's modulus and low thermal expansion coefficient. Thus, understanding wear properties of this composite is of a great importance. In this study wear behavior of an in-situ Al-Mg2Si composite, prepared from a simple casting route, has been investigated using a pin-on-disc configuration concerning the effect of Mg2Si volume fractions, 15, 20 and 25% respectively. It was found that the weight loss increases with increase in reinforce volume fraction which can be due to a coarse morphology of primary Mg2Si particles. It was found that the variations of weight loss with sliding distance comprise different regimes of which the mechanisms are discussed.
Oh, Jungsu S.; Kim, Jae Seung; Chae, Sun Young; Oh, Minyoung; Oh, Seung Jun; Cha, Seung Nam; Chang, Ho-Jong; Lee, Chong Sik; Lee, Jae Hong
2017-03-01
We present an optimized voxelwise statistical parametric mapping (SPM) of partial-volume (PV)-corrected positron emission tomography (PET) of 11C Pittsburgh Compound B (PiB), incorporating the anatomical precision of magnetic resonance image (MRI) and amyloid β (A β) burden-specificity of PiB PET. First, we applied region-based partial-volume correction (PVC), termed the geometric transfer matrix (GTM) method, to PiB PET, creating MRI-based lobar parcels filled with mean PiB uptakes. Then, we conducted a voxelwise PVC by multiplying the original PET by the ratio of a GTM-based PV-corrected PET to a 6-mm-smoothed PV-corrected PET. Finally, we conducted spatial normalizations of the PV-corrected PETs onto the study-specific template. As such, we increased the accuracy of the SPM normalization and the tissue specificity of SPM results. Moreover, lobar smoothing (instead of whole-brain smoothing) was applied to increase the signal-to-noise ratio in the image without degrading the tissue specificity. Thereby, we could optimize a voxelwise group comparison between subjects with high and normal A β burdens (from 10 patients with Alzheimer's disease, 30 patients with Lewy body dementia, and 9 normal controls). Our SPM framework outperformed than the conventional one in terms of the accuracy of the spatial normalization (85% of maximum likelihood tissue classification volume) and the tissue specificity (larger gray matter, and smaller cerebrospinal fluid volume fraction from the SPM results). Our SPM framework optimized the SPM of a PV-corrected A β PET in terms of anatomical precision, normalization accuracy, and tissue specificity, resulting in better detection and localization of A β burdens in patients with Alzheimer's disease and Lewy body dementia.
Directory of Open Access Journals (Sweden)
Kouhei Kamiya
Full Text Available PURPOSE: Previous studies suggest that compression and stretching of the corticospinal tract (CST potentially cause treatable gait disturbance in patients with idiopathic normal pressure hydrocephalus (iNPH. Measurement of axon diameter with diffusion MRI has recently been used to investigate microstructural alterations in neurological diseases. In this study, we investigated alterations in the axon diameter and intra-axonal fraction of the CST in iNPH by q-space imaging (QSI analysis. METHODS: Nineteen patients with iNPH and 10 age-matched controls were recruited. QSI data were obtained with a 3-T system by using a single-shot echo planar imaging sequence with the diffusion gradient applied parallel to the antero-posterior axis. By using a two-component low-q fit model, the root mean square displacements of intra-axonal space ( = axon diameter and intra-axonal volume fraction of the CST were calculated at the levels of the internal capsule and body of the lateral ventricle, respectively. RESULTS: Wilcoxon's rank-sum test revealed a significant increase in CST intra-axonal volume fraction at the paraventricular level in patients (p<0.001, whereas no significant difference was observed in the axon diameter. At the level of the internal capsule, neither axon diameter nor intra-axonal volume fraction differed significantly between the two groups. CONCLUSION: Our results suggest that in patients with iNPH, the CST does not undergo irreversible axonal damage but is rather compressed and/or stretched owing to pressure from the enlarged ventricle. These analyses of axon diameter and intra-axonal fraction yield insights into microstructural alterations of the CST in iNPH.
Energy Technology Data Exchange (ETDEWEB)
Schwab, K.; Brack, W. [UFZ - Helmholtz Centre or Environmental Research, Leipzig (Germany). Dept. of Effect-Directed Analysis
2007-06-15
Background, Aim and Scope: Effect-directed analysis (EDA) is a powerful tool for the identification of key toxicants in complex environmental samples. In most cases, EDA is based on total extraction of organic contaminants leading to an erroneous prioritization with regard to hazard and risk. Bioaccessibility-directed extraction aims to discriminate between contaminants that take part in partitioning between sediment and biota in a relevant time frame and those that are enclosed in structures, that do not allow rapid desorption. Standard protocols of targeted extraction of rapidly desorbing, and thus bioaccessible fraction using TENAX {sup registered} are based only on small amounts of sediment. In order to get sufficient amounts of extracts for subsequent biotesting, fractionation, and structure elucidation a large volume extraction technique needs to be developed applying one selected extraction time and excluding toxic procedural blanks. Materials and Methods: Desorption behaviour of sediment contaminants was determined by a consecutive solid-solid extraction of sediment using TENAX {sup registered} fitting a tri-compartment model on experimental data. Time needed to remove the rapidly desorbing fraction trap was calculated to select a fixed extraction time for single extraction procedures. Up-scaling by about a factor of 100 provided a large volume extraction technique for EDA. Reproducibility and comparability to small volume approach were proved. Blanks of respective TENAX {sup registered} mass were investigated using Scenedesmus vacuolatus and Artemia salina as test organisms. Results: Desorption kinetics showed that 12 to 30 % of sediment associated pollutants are available for rapid desorption. t{sub r}ap is compound dependent and covers a range of 2 to 18 h. On that basis a fixed extraction time of 24 h was selected. Validation of large volume approach was done by the means of comparison to small method and reproducibility. The large volume showed a good
STATEWIDE MAPPING OF FLORIDA SOIL RADON POTENTIALS VOLUME 1. TECHNICAL REPORT
The report gives results of a statewide mapping of Florida soil radon potentials. Statewide maps identify Florida Regions with different levels of soil radon potential. The maps provide scientific estimates of regional radon potentials that can serve as a basis for implementing r...
STATEWIDE MAPPING OF FLORIDA SOIL RADON POTENTIALS VOLUME 2. APPENDICES A-P
The report gives results of a statewide mapping of Florida soil radon potentials. Statewide maps identify Florida Regions with different levels of soil radon potential. The maps provide scientific estimates of regional radon potentials that can serve as a basis for implementing r...
DEFF Research Database (Denmark)
Oddershede, Jette; Majkut, Marta; Caosyd, Qinghua
2015-01-01
a bulk sample. Such information is critical to furthering our understanding of the grainscale interactions of ferroic domains and their influence on bulk properties. The method also provides a validation tool for mesoscopic ferroic domain modelling efforts. The mathematical formulations presented here......A method for the extension of the three-dimensional X-ray diffraction technique to allow the extraction of domain volume fractions in polycrystalline ferroic materials is presented. This method gives access to quantitative domain volume fractions of hundreds of independent embedded grains within...... are applied to tetragonal coarse-grained Ba0.88Ca0.12Zr0.06Ti0.94O3 and rhombohedral fine-grained (0.82)Bi0.5Na0.5TiO3–(0.18)Bi0.5K0.5TiO3 electroceramic materials. The fitted volume fraction information is used to calculate grain-scale non-180° ferroelectric domain switching strains. The absolute errors...
Directory of Open Access Journals (Sweden)
H. Shokrollahi
2016-03-01
Full Text Available The purpose of this work is to investigate the effects of the volume fraction and bimodal distribution of solid particles on the compression and tension behavior of the Co-ferrite-based magneto-rheological fluids (MRFs containing silicon oil as a carrier. Hence, Co-ferrite particles (CoFe2O4 with two various sizes were synthesized by the chemical co-precipitation method and mixed so as to prepare the bimodal MRF. The X-Ray Diffraction (XRD analysis, Fourier Transform Infrared Spectroscopy (FTIR, Laser Particle Size Analysis (LPSA and Vibrating Sample Magnetometer (VSM were conducted to examine the structural and magnetic properties, respectively. The results indicated that the increase of the volume fraction has a direct increasing influence on the values of the compression and tension strengths of fluids. In addition, the compression and tension strengths of the mixed MRF sample (1.274 and 0.647 MPa containing 60 and 550 nm samples were higher than those of the MRF sample with the same volume fraction and uniform particle size of 550 nm.
Groundwater contaminant plume maps and volumes, 100-K and 100-N Areas, Hanford Site, Washington
Johnson, Kenneth H.
2016-09-27
extents are shown graphically and in tabular form for comparison to previous estimates. Plume data also were interpolated to a finer grid (10 × 10 m) for some processing, particularly to estimate volumes of contaminated groundwater. However, hydrogeologic transport modeling was not considered for the interpolation. The compilation of plume extents for each contaminant also allowed estimates of overlap of the plumes or areas with more than one contaminant above regulatory standards.A mapping of saturated aquifer thickness also was derived across the 100-K and 100–N study area, based on the vertical difference between the groundwater level (water table) at the top and the altitude of the top of the Ringold Upper Mud geologic unit, considered the bottom of the uppermost unconfined aquifer. Saturated thickness was calculated for each cell in the finer (10 × 10 m) grid. The summation of the cells’ saturated thickness values within each polygon of plume regulatory exceedance provided an estimate of the total volume of contaminated aquifer, and the results also were checked using a SURFER® volumetric integration procedure. The total volume of contaminated groundwater in each plume was derived by multiplying the aquifer saturated thickness volume by a locally representative value of porosity (0.3).Estimates of the uncertainty of the plume delineation also are presented. “Upper limit” plume delineations were calculated for each contaminant using the same procedure as the “average” plume extent except with values at each well that are set at a 95-percent upper confidence limit around the log-normally transformed mean concentrations, based on the standard error for the distribution of the mean value in that well; “lower limit” plumes are calculated at a 5-percent confidence limit around the geometric mean. These upper- and lower-limit estimates are considered unrealistic because the statistics were increased or decreased at each well simultaneously and were not
Tao, Qian; van der Tol, Pieternel; Berendsen, Floris F; Paiman, Elisabeth H M; Lamb, Hildo J; van der Geest, Rob J
2017-09-27
Myocardial tissue characterization by MR T1 and extracellular volume (ECV) mapping has demonstrated clinical value. The modified Look-Locker inversion recovery (MOLLI) sequence is a standard mapping technique, but its quality can be negatively affected by motion. To develop a robust motion correction method for T1 and ECV mapping. Retrospective analysis of clinical data. Fifty patients who were referred to cardiac MR exam for T1 mapping. 3.0T cardiac MRI with precontrast and postcontrast MOLLI acquisition of the left ventricle (LV). A groupwise registration method based on principle component analysis (PCA) was developed to register all MOLLI frames simultaneously. The resulting T1 and ECV maps were compared to those from the original and motion-corrected MOLLI with pairwise registration, in terms of standard deviation (SD) error. Paired variables were compared using the Wilcoxon signed-rank test. The groupwise registration method demonstrated improved registration performance compared to pairwise registration, with the T1 SD error reduced from 31 ± 20 msec to 26 ± 15 msec (P registration was significantly shorter than that of the pairwise registration, 17.5 ± 3.0 seconds compared to 43.5 ± 2.2 seconds (P registration scheme. The method led to lower mapping error compared to the conventional pairwise registration method in reduced execution time. 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017. © 2017 International Society for Magnetic Resonance in Medicine.
Directory of Open Access Journals (Sweden)
Jonny Nordström
2017-11-01
Full Text Available Abstract Background Quantitative measurement of myocardial blood flow (MBF is of increasing interest in the clinical assessment of patients with suspected coronary artery disease (CAD. 15O-water positron emission tomography (PET is considered the gold standard for non-invasive MBF measurements. However, calculation of left ventricular (LV volumes and ejection fraction (EF is not possible from standard 15O-water uptake images. The purpose of the present work was to investigate the possibility of calculating LV volumes and LVEF from cardiac-gated parametric blood volume (V B 15O-water images and from first pass (FP images. Sixteen patients with mitral or aortic regurgitation underwent an eight-gate dynamic cardiac-gated 15O-water PET/CT scan and cardiac MRI. V B and FP images were generated for each gate. Calculations of end-systolic volume (ESV, end-diastolic volume (EDV, stroke volume (SV and LVEF were performed with automatic segmentation of V B and FP images, using commercially available software. LV volumes and LVEF were calculated with surface-, count-, and volume-based methods, and the results were compared with gold standard MRI. Results Using V B images, high correlations between PET and MRI ESV (r = 0.89, p 0.86, p < 0.001. Conclusion Calculation of LV volumes and LVEF from dynamic 15O-water PET is feasible and shows good correlation with MRI. However, the analysis method is laborious, and future work is needed for more automation to make the method more easily applicable in a clinical setting.
Weingärtner, Sebastian; Meßner, Nadja M; Zöllner, Frank G; Akçakaya, Mehmet; Schad, Lothar R
2017-08-01
To study the feasibility of black-blood contrast in native T1 mapping for reduction of partial voluming at the blood-myocardium interface. A saturation pulse prepared heart-rate-independent inversion recovery (SAPPHIRE) T1 mapping sequence was combined with motion-sensitized driven-equilibrium (MSDE) blood suppression for black-blood T1 mapping at 3 Tesla. Phantom scans were performed to assess the T1 time accuracy. In vivo black-blood and conventional SAPPHIRE T1 mapping was performed in eight healthy subjects and analyzed for T1 times, precision, and inter- and intraobserver variability. Furthermore, manually drawn regions of interest (ROIs) in all T1 maps were dilated and eroded to analyze the dependence of septal T1 times on the ROI thickness. Phantom results and in vivo myocardial T1 times show comparable accuracy with black-blood compared to conventional SAPPHIRE (in vivo: black-blood: 1562 ± 56 ms vs. conventional: 1583 ± 58 ms, P = 0.20); Using black-blood SAPPHIRE precision was significantly lower (standard deviation: 133.9 ± 24.6 ms vs. 63.1 ± 6.4 ms, P T1 time measurement was not possible. Significantly increased interobserver interclass correlation coefficient (ICC) (0.996 vs. 0.967, P = 0.011) and similar intraobserver ICC (0.979 vs. 0.939, P = 0.11) was obtained with the black-blood sequence. Conventional SAPPHIRE showed strong dependence on the ROI thickness (R(2) = 0.99). No such trend was observed using the black-blood approach (R(2) = 0.29). Black-blood SAPPHIRE successfully eliminates partial voluming at the blood pool in native myocardial T1 mapping while providing accurate T1 times, albeit at a reduced precision. Magn Reson Med 78:484-493, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.
Directory of Open Access Journals (Sweden)
A. Pantet
2010-01-01
Full Text Available Coastal erosion results from a combination of various factors, both natural and humaninduced, which have different time and space patterns. In addition, uncertainties still remain about the interactions of the forcing agents, as well as on the significance of non-local causes of erosion. We focused about the surface sediments in the Marennes Oléron bay, after a general description of the site that has many various activities. The superficial sediments show a mechanical behavior, mainly depends on the fine fraction for a composition that contains up to 60% of sandy material. Fine sediments fraction has a typical yield stress depending naturally of concentration or water content. This yield could be modified slightly or significantly by adding silt or sand. As a result, the rheological measurement sensitivity allows us to characterize five typical sediments that correlate with solid fraction and fine fraction.
Mandapaka, Sangeeta; Hamilton, Craig A; Morgan, Timothy M; Hundley, William Gregory
2011-01-01
During cardiovascular stress, if right ventricular (RV) stroke volume exceeds left ventricular (LV) stroke volume, then a large volume of blood is displaced into the pulmonary circulation that may precipitate pulmonary edema. We sought to determine the metrics by which cardiovascular magnetic resonance (CMR) could measure simultaneous displacement of RV and LV stroke volumes during dobutamine stress. Thirteen healthy subjects (5 women) aged 53 ± 10 years without medical conditions and taking no medications underwent 2 CMR examinations at 1.5 T separated by 4 to 8 weeks in which RV and LV stroke volumes were determined during intravenous dobutamine and atropine infused to achieve 80% of the maximum predicted heart rate response for age. The RV and LV stroke volumes were highly correlated at each level of stress (rest: r = 0.98, P = 0.007; low stress: r = 0.87, P = 0.001; and peak stress: r = 0.88, P = 0.001), and the mean difference in SV at each level of stress (rest, low stress, and peak stress was 0 to 2 mL on examinations 1 and 2. Simultaneous change in right and left ventricular stroke volumes can be assessed in a highly reproducible manner throughout the course of dobutamine CMR stress administered to achieve 80% of maximum predicted heart rate response for age. This technology may help identify discrepancies in RV and LV stroke volumes during cardiovascular stress that are associated with the development of pulmonary edema.
Griffiths, A E; Wang, W; Hagen, F K; Fay, P J
2011-08-01
Neutralizing factor (F) VIII antibodies develop in approximately 30% of individuals with hemophilia A and show specificity to multiple sites in the FVIII protein. Reactive epitopes to an immobilized IgG fraction prepared from a high-titer, FVIII inhibitor plasma were determined after immuno-precipitation (IP) of tryptic and chymotryptic peptides derived from digests of the A1 and A2 subunits of FVIIIa and FVIII light chain. Peptides were detected and identified using highly sensitive liquid chromatography-mass spectrometry (LC-MS). Coverage maps of the A1 subunit, A2 subunit and light chain represented 79%, 69% and 90%, respectively, of the protein sequences. Dot blots indicated that the inhibitor IgG reacted with epitopes contained within each subunit of FVIIIa. IP coupled with LC-MS identified 19 peptides representing epitopes from all FVIII A and C domains. The majority of peptides (10) were derived from the A2 domain. Three peptides mapped to the C2 domain, while two mapped to the A1 and A3 domains, and single peptides mapped to the a1 segment and C1 domain. Epitopes were typically defined by peptide sequences of < 12 residues. IP coupled with LC-MS identified extensive antibody reactivity at high resolution over the entire functional FVIII molecule and yielded sequence lengths of < 15 residues. A number of the peptides identified mapped to known sequences involved in functionally important protein-protein and protein-membrane interactions. © 2011 International Society on Thrombosis and Haemostasis.
Garg, Pankaj; Broadbent, David A; Swoboda, Peter P; Foley, James R J; Fent, Graham J; Musa, Tarique A; Ripley, David P; Erhayiem, Bara; Dobson, Laura E; McDiarmid, Adam K; Haaf, Philip; Kidambi, Ananth; van der Geest, Rob J; Greenwood, John P; Plein, Sven
2017-07-01
Late gadolinium enhancement (LGE) imaging overestimates acute infarct size. The main aim of this study was to investigate whether acute extracellular volume (ECV) maps can reliably quantify myocardial area at risk (AAR) and final infarct size (IS). Fifty patients underwent cardiovascular magnetic resonance imaging acutely (24-72 hours) and at convalescence (3 months). The cardiovascular magnetic resonance protocol included cines, T2-weighted imaging, native T1 maps, 15-minute post-contrast T1 maps, and LGE. Optimal AAR and IS ECV thresholds were derived in a validation group of 10 cases (160 segments). Eight hundred segments (16 per patient) were analyzed to quantify AAR/IS by ECV maps (ECV thresholds for AAR is 33% and IS is 46%), T2-weighted imaging, T1 maps, and acute LGE. Follow-up LGE imaging was used as the reference standard for final IS and viability assessment. The AAR derived from ECV maps (threshold of >33) demonstrated good agreement with T2-weighted imaging-derived AAR (bias, 0.18; 95% confidence interval [CI], -1.6 to 1.3) and AAR derived from native T1 maps (bias=1; 95% CI, -0.37 to 2.4). ECV demonstrated the best linear correlation to final IS at a threshold of >46% (R=0.96; 95% CI, 0.92-0.98; Pmaps demonstrated better agreement with final IS than acute IS on LGE (ECV maps: bias, 1.9; 95% CI, 0.4-3.4 versus LGE imaging: bias, 10; 95% CI, 7.7-12.4). On multiple variable regression analysis, the number of nonviable segments was independently associated with IS by ECV maps (β=0.86; Pmaps can reliably quantify AAR and final IS in reperfused acute myocardial infarction. Acute ECV maps were superior to acute LGE in terms of agreement with final IS. IS quantified by ECV maps are independently associated with viability at follow-up. © 2017 American Heart Association, Inc.
Mertzanidou, Thomy; Hipwell, John H; Reis, Sara; Hawkes, David J; Ehteshami Bejnordi, Babak; Dalmis, Mehmet; Vreemann, Suzan; Platel, Bram; van der Laak, Jeroen; Karssemeijer, Nico; Hermsen, Meyke; Bult, Peter; Mann, Ritse
2017-03-01
In breast imaging, radiological in vivo images, such as x-ray mammography and magnetic resonance imaging (MRI), are used for tumor detection, diagnosis, and size determination. After excision, the specimen is typically sliced into slabs and a small subset is sampled. Histopathological imaging of the stained samples is used as the gold standard for characterization of the tumor microenvironment. A 3D volume reconstruction of the whole specimen from the 2D slabs could facilitate bridging the gap between histology and in vivo radiological imaging. This task is challenging, however, due to the large deformation that the breast tissue undergoes after surgery and the significant undersampling of the specimen obtained in histology. In this work, we present a method to reconstruct a coherent 3D volume from 2D digital radiographs of the specimen slabs. To reconstruct a 3D breast specimen volume, we propose the use of multiple target neighboring slices, when deforming each 2D slab radiograph in the volume, rather than performing pairwise registrations. The algorithm combines neighborhood slice information with free-form deformations, which enables a flexible, nonlinear deformation to be computed subject to the constraint that a coherent 3D volume is obtained. The neighborhood information provides adequate constraints, without the need for any additional regularization terms. The volume reconstruction algorithm is validated on clinical mastectomy samples using a quantitative assessment of the volume reconstruction smoothness and a comparison with a whole specimen 3D image acquired for validation before slicing. Additionally, a target registration error of 5 mm (comparable to the specimen slab thickness of 4 mm) was obtained for five cases. The error was computed using manual annotations from four observers as gold standard, with interobserver variability of 3.4 mm. Finally, we illustrate how the reconstructed volumes can be used to map histology images to a 3D specimen
Cottin, Y; Touzery, C; Guy, F; Lalande, A; Ressencourt, O; Roy, S; Walker, P M; Louis, P; Brunotte, F; Wolf, J E
1999-11-01
To determine the extent to which the number of planes imaged at magnetic resonance (MR) imaging could be reduced without modifying the calculated volume and thickness of the left ventricle. Sixty-one patients were examined after a myocardial infarction. The whole left ventricle was imaged by using 5-mm contiguous breath-hold cine MR short-axis sections with no gap (SAng) (two-dimensional fast low-angle shot sequence, 9/4.8 [repetition time msec/echo time msec]). The effect of omitting one section in two (short-axis sections with 5-mm gap [SA5 mm]) or two sections in three (short-axis sections with 10-mm gap [SA10 mm]) was studied. In the comparison of SA5 mm or SA10 mm with respect to the reference SAng, the standard error of the estimate (SEE) for the diastolic volume did not exceed the 6.1% interobserver SEE, and the SEE for the ejection fraction remained lower than the 3% interobserver SEE. The measured wall thickness was not affected. In addition, six simple geometric models were compared with SAng and yielded an SEE of 9.5%-28.1% for the diastolic volume and 3.8%-13.3% for the ejection fraction. In the study of left ventricles with heterogeneous contractility, short-axis imaging is more accurate than geometric modeling and permits wall thickness measurements when an intersection gap of 5 or 10 mm is used.
Ferreira, Vanessa M; Wijesurendra, Rohan S; Liu, Alexander; Greiser, Andreas; Casadei, Barbara; Robson, Matthew D; Neubauer, Stefan; Piechnik, Stefan K
2015-08-28
T1-mapping using the Shortened Modified Look-Locker Inversion Recovery (ShMOLLI) technique enables non-invasive assessment of important myocardial tissue characteristics. However, tachyarrhythmia may cause mistriggering and inaccurate T1 estimation. We set out to test whether systolic T1-mapping might overcome this, and whether T1 values or data quality would be significantly different compared to conventional diastolic T1-mapping. Native T1 maps were acquired using ShMOLLI at 1.5 T (Magnetom Avanto, Siemens Healthcare) in 10 healthy volunteers (5 male) in sinus rhythm, at varying prescribed trigger delay (TD) times: 0, 50, 100 and 150 ms (all "systolic"), 340 ms (MOLLI TD 500 ms, the conventional TD for ShMOLLI) and also "end diastolic". T1 maps were also acquired using a shorter readout, to explore the effect of reducing image readout time and sensitivity to systolic motion. The feasibility and image quality of systolic T1-mapping was tested in 15 patients with tachyarrhythmia (n = 13 atrial fibrillation, n = 2 sinus tachycardia; mean HR range 93-121 bpm). In healthy volunteers, systolic readout increased the thickness of myocardium compared to the diastolic readout. There was a small overall effect of TD on T1 values (p = 0.04), with slightly shorter T1 values in systole compared to diastole (maximum difference 10 ms). While there were apparent gender differences (with no effect of TD on T1 values in males, more marked differences in females, and exaggeration of this effect in thinner myocardial segments in females), dilatation and erosion of contours suggested that the effect of TD on T1 in females was almost entirely due to more partial-volume effects in diastole. All T1 maps were of excellent quality, but systolic TD and shorter readout were associated with less variability in segmental T1 values. In tachycardic patients, systolic acquisitions produced consistently excellent T1 maps (median R (2) = 0.993). In healthy volunteers, systolic
Selkowitz, D.J.
2010-01-01
Shrub cover appears to be increasing across many areas of the Arctic tundra biome, and increasing shrub cover in the Arctic has the potential to significantly impact global carbon budgets and the global climate system. For most of the Arctic, however, there is no existing baseline inventory of shrub canopy cover, as existing maps of Arctic vegetation provide little information about the density of shrub cover at a moderate spatial resolution across the region. Remotely-sensed fractional shrub canopy maps can provide this necessary baseline inventory of shrub cover. In this study, we compare the accuracy of fractional shrub canopy (> 0.5 m tall) maps derived from multi-spectral, multi-angular, and multi-temporal datasets from Landsat imagery at 30 m spatial resolution, Moderate Resolution Imaging SpectroRadiometer (MODIS) imagery at 250 m and 500 m spatial resolution, and MultiAngle Imaging Spectroradiometer (MISR) imagery at 275 m spatial resolution for a 1067 km2 study area in Arctic Alaska. The study area is centered at 69 ??N, ranges in elevation from 130 to 770 m, is composed primarily of rolling topography with gentle slopes less than 10??, and is free of glaciers and perennial snow cover. Shrubs > 0.5 m in height cover 2.9% of the study area and are primarily confined to patches associated with specific landscape features. Reference fractional shrub canopy is determined from in situ shrub canopy measurements and a high spatial resolution IKONOS image swath. Regression tree models are constructed to estimate fractional canopy cover at 250 m using different combinations of input data from Landsat, MODIS, and MISR. Results indicate that multi-spectral data provide substantially more accurate estimates of fractional shrub canopy cover than multi-angular or multi-temporal data. Higher spatial resolution datasets also provide more accurate estimates of fractional shrub canopy cover (aggregated to moderate spatial resolutions) than lower spatial resolution datasets
Garcia-Lazaro, Haydee Guadalupe; Becerra-Laparra, Ivonne; Cortez-Conradis, David; Roldan-Valadez, Ernesto
2016-01-01
Summary Several parameters of brain integrity can be derived from diffusion tensor imaging. These include fractional anisotropy (FA) and mean diffusivity (MD). Combination of these variables using multivariate analysis might result in a predictive model able to detect the structural changes of human brain aging. Our aim was to discriminate between young and older healthy brains by combining structural and volumetric variables from brain MRI: FA, MD, and white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF) volumes. This was a cross-sectional study in 21 young (mean age, 25.71±3.04 years; range, 21–34 years) and 10 elderly (mean age, 70.20±4.02 years; range, 66–80 years) healthy volunteers. Multivariate discriminant analysis, with age as the dependent variable and WM, GM and CSF volumes, global FA and MD, and gender as the independent variables, was used to assemble a predictive model. The resulting model was able to differentiate between young and older brains: Wilks’ λ = 0.235, χ2 (6) = 37.603, p = .000001. Only global FA, WM volume and CSF volume significantly discriminated between groups. The total accuracy was 93.5%; the sensitivity, specificity and positive and negative predictive values were 91.30%, 100%, 100% and 80%, respectively. Global FA, WM volume and CSF volume are parameters that, when combined, reliably discriminate between young and older brains. A decrease in FA is the strongest predictor of membership of the older brain group, followed by an increase in WM and CSF volumes. Brain assessment using a predictive model might allow the follow-up of selected cases that deviate from normal aging. PMID:27027893
Directory of Open Access Journals (Sweden)
Mina Park
Full Text Available To assess the added value of arterial enhancement fraction (AEF color maps for the differentiation of small metastases from hepatic benign lesions.We retrospectively analyzed 46 patients with colorectal cancer who underwent multiphasic liver CT imaging and had low-attenuating liver lesions smaller than 3 cm (123 total lesions; metastasis: benign = 32:91. AEF color maps of the liver were created from multiphasic liver CT images using dedicated software. Two radiologists independently reviewed multiphasic CT image sets alone and in combination with image sets with AEF color maps using a five-point scale. The additional diagnostic value of the color maps was assessed by means of receiver-operating characteristic (ROC analysis.The area under the ROC curve (Az increased when multiphasic CT images were combined with AEF color map analysis as compared with evaluation based only on multiphasic CT images (from 0.698 to 0.897 for reader 1, and from 0.825 to 0.945 for reader 2; P < 0.001 and 0.002, respectively. The increase Az was especially significant for lesions less than 1 cm (from 0.702 to 0.888 for reader 1, and from 0.768 to 0.958 for reader 2; P = 0.001 and P = 0.001, respectively. The mean AEF of tumor-adjacent parenchyma (35.07 ± 27.2 was significantly higher than that of tumor-free liver parenchyma (27.3 ± 20.6 (P = 0.04.AEF color mapping can improve the diagnostic performance for small hepatic metastases from colorectal cancer and may allow for the elimination of additional examinations.
DEFF Research Database (Denmark)
Svarer, Claus; Madsen, Karina; Hasselbalch, Steen G.
2005-01-01
The purpose of this study was to develop and validate an observer-independent approach for automatic generation of volume-of-interest (VOI) brain templates to be used in emission tomography studies of the brain. The method utilizes a VOI probability map created on the basis of a database of several...... subjects' MR-images, where VOI sets have been defined manually. High-resolution structural MR-images and 5-HT(2A) receptor binding PET-images (in terms of (18)F-altanserin binding) from 10 healthy volunteers and 10 patients with mild cognitive impairment were included for the analysis. A template including...... delineation of the VOI set. The approach was also shown to work equally well in individuals with pronounced cerebral atrophy. Probability-map-based automatic delineation of VOIs is a fast, objective, reproducible, and safe way to assess regional brain values from PET or SPECT scans. In addition, the method...
DEFF Research Database (Denmark)
Wejdemann, Christian; Poulsen, Henning Friis; Lienert, U.
2009-01-01
dislocation density called subgrains bounded by dislocation rich walls. With the new technique reciprocal space maps, consisting of sharp peaks arising from the subgrains superimposed on a cloud of lower intensity arising from the dislocation walls, are obtained, which allows properties such as subgrain...
Energy Technology Data Exchange (ETDEWEB)
Guzik, S; McCorquodale, P; Colella, P
2011-12-16
A fourth-order accurate finite-volume method is presented for solving time-dependent hyperbolic systems of conservation laws on mapped grids that are adaptively refined in space and time. Novel considerations for formulating the semi-discrete system of equations in computational space combined with detailed mechanisms for accommodating the adapting grids ensure that conservation is maintained and that the divergence of a constant vector field is always zero (freestream-preservation property). Advancement in time is achieved with a fourth-order Runge-Kutta method.
Energy Technology Data Exchange (ETDEWEB)
Chawla, N.; Andres, C.; Jones, J.W. [Univ. of Michigan, Ann Arbor, MI (United States); Allison, J.E. [Ford Motor Co., Dearborn, MI (United States)
1998-11-01
The effect of SiC volume fraction and particle size on the fatigue behavior of 2080 Al was investigated. Matrix microstructure in the composite and the unreinforced alloy was held relatively constant by the introduction of a deformation stage prior to aging. It was found that increasing volume fraction and decreasing particle size resulted in an increase in fatigue resistance. Mechanisms responsible for this behavior are described in terms of load transfer from the matrix to the high stiffness reinforcement, increasing obstacles for dislocation motion in the form of S{prime} precipitates, and the decrease in strain localization with decreasing reinforcement interparticle spacing as a result of reduced particle size. Microplasticity was also observed in the composite, in the form of stress-strain hysteresis loops, and is related to stress concentrations at the poles of the reinforcement. Finally, intermetallic inclusions in the matrix acted as fatigue crack initiation sites. The effect of inclusion size and location on fatigue life of the composites is discussed.
Directory of Open Access Journals (Sweden)
Hamed Sabet
2013-06-01
Full Text Available In this investigation, three different chemical compositions of Fe-Cr-C alloys were fabricated on AISI 1010 steel substrates by gas tungsten arc welding (GTAW. The optical emission spectroscopy (OES, optical microscopy (OM, scanning electron microscopy (SEM, techniques and corrosion test were used for determining chemical composition studying the microstructure and corrosion behavior of the Fe-Cr-C alloys. The OM and SEM results show that the microstructure of these alloys consisted of (Cr,Fe7C3 carbides with austenite, and by increasing of the carbon and chromium content in hardfacing alloys, the volume fraction of (Cr,Fe7C3 carbides in microstructure was increased. The polarization curves of the corrosion tests show that the increase of the volume fraction of (Cr,Fe7C3 carbides in the microstructure promotes the corrosion resistance of the Fe-Cr-C hardfacing alloys. The corrosion mechanism of the Fe-Cr-C hardfacing alloys was intergranular and galvanic corrosion.
Hu, Chun-Hong; Hu, Su; Gao, Xi; Sun, Chun-Ming; Gan, Wen-Juan; Liu, Yun-Lian; Wen, Fang; Dai, Qi-Chun; Li, Ping
2015-01-01
To investigate the feasibility of tissue similarity map (TSM)-based relative cerebral blood volume (rCBV) assessment in evaluating the hemodynamic characteristics of gliomas and in differentiating high-grade gliomas from low-grade ones without concentration time curve (CTC). TSM-based rCBV (rCBV TSM ) and conventional rCBV (rCBV PWI ) maps were generated (n = 35). The differences in percentage and concordance correlation coefficient (CCC) of the rCBV TSM and rCBV PWI ratios were calculated. The Mann-Whitney test and the receiver operating characteristic (ROC) curve analysis were also performed to examine the relationships of rCBV ratios between high- and low-grade gliomas. The improvement factors of signal to noise ratio (SNR) of rCBV TSM maps were also calculated. The mean difference in percentage between rCBV TSM and rCBV PWI ratios was 4.29 ± 2.62%. The CCC of rCBV TSM and rCBV PWI ratios was 0.9974, with 95% confidence interval of 0.9948, 0.9987, which implied a high agreement between them. The Mann-Whitney test suggested that the rCBV TSM and rCBV PWI ratios of high-grade gliomas were significantly different from those of low-grade gliomas (P TSM map were 1.31 ± 0.24 for glioma and 1.28 ± 0.24 for normal white matter. It is feasible to use rCBV TSM in the evaluation of hemodynamic characteristics of gliomas and differentiation of high- and low-grade gliomas without CTC. Moreover, rCBV TSM maps possess a higher SNR, which allows potentially more accurate diagnosis compared with the conventional ones.
Mapping growing stock volume and forest live biomass: a case study of the Polissya region of Ukraine
Bilous, Andrii; Myroniuk, Viktor; Holiaka, Dmytrii; Bilous, Svitlana; See, Linda; Schepaschenko, Dmitry
2017-10-01
Forest inventory and biomass mapping are important tasks that require inputs from multiple data sources. In this paper we implement two methods for the Ukrainian region of Polissya: random forest (RF) for tree species prediction and k-nearest neighbors (k-NN) for growing stock volume and biomass mapping. We examined the suitability of the five-band RapidEye satellite image to predict the distribution of six tree species. The accuracy of RF is quite high: ~99% for forest/non-forest mask and 89% for tree species prediction. Our results demonstrate that inclusion of elevation as a predictor variable in the RF model improved the performance of tree species classification. We evaluated different distance metrics for the k-NN method, including Euclidean or Mahalanobis distance, most similar neighbor (MSN), gradient nearest neighbor, and independent component analysis. The MSN with the four nearest neighbors (k = 4) is the most precise (according to the root-mean-square deviation) for predicting forest attributes across the study area. The k-NN method allowed us to estimate growing stock volume with an accuracy of 3 m3 ha-1 and for live biomass of about 2 t ha-1 over the study area.
Map It: Tools for Charting the Vast Territories of Your Mind. Interactive Comics Volume 1.
Margulies, Nancy
Teachers and students are continuously searching for fun and easy ways to help students organize and enhance their thoughts. This document uses interactive comics to describe the process of mind mapping to aid learners in developing new and creative ideas. The document also includes a brief overview of the functions of the brain's right and left…
Automatic estimation of excavation volume from laser mobile mapping data for mountain road widening
Wang, J.; González-Jorge, H.; Lindenbergh, R.; Arias-Sánchez, P.; Menenti, M.
2013-01-01
Roads play an indispensable role as part of the infrastructure of society. In recent years, society has witnessed the rapid development of laser mobile mapping systems (LMMS) which, at high measurement rates, acquire dense and accurate point cloud data. This paper presents a way to automatically
Directory of Open Access Journals (Sweden)
Somayya Komal
2016-10-01
Full Text Available In this article, we introduced the best proximity point theorems for $\\mathcal{Z}$-contraction and Suzuki type $\\mathcal{Z}$-contraction in the setting of complete metric spaces. Also by the help of weak $P$-property and $P$-property, we proved existence and uniqueness of best proximity point. There is a simple example to show the validity of our results. Our results extended and unify many existing results in the literature. Moreover, an application to fractional order functional differential equation is discussed.
Keyes, S D; Gillard, F; Soper, N; Mavrogordato, M N; Sinclair, I; Roose, T
2016-06-14
The mechanical impedance of soils inhibits the growth of plant roots, often being the most significant physical limitation to root system development. Non-invasive imaging techniques have recently been used to investigate the development of root system architecture over time, but the relationship with soil deformation is usually neglected. Correlative mapping approaches parameterised using 2D and 3D image data have recently gained prominence for quantifying physical deformation in composite materials including fibre-reinforced polymers and trabecular bone. Digital Image Correlation (DIC) and Digital Volume Correlation (DVC) are computational techniques which use the inherent material texture of surfaces and volumes, captured using imaging techniques, to map full-field deformation components in samples during physical loading. Here we develop an experimental assay and methodology for four-dimensional, in vivo X-ray Computed Tomography (XCT) and apply a Digital Volume Correlation (DVC) approach to the data to quantify deformation. The method is validated for a field-derived soil under conditions of uniaxial compression, and a calibration study is used to quantify thresholds of displacement and strain measurement. The validated and calibrated approach is then demonstrated for an in vivo test case in which an extending maize root in field-derived soil was imaged hourly using XCT over a growth period of 19h. This allowed full-field soil deformation data and 3D root tip dynamics to be quantified in parallel for the first time. This fusion of methods paves the way for comparative studies of contrasting soils and plant genotypes, improving our understanding of the fundamental mechanical processes which influence root system development. Copyright © 2016 Elsevier Ltd. All rights reserved.
Taylor, Graham K; Holbrook, Robert Iain; de Perera, Theresa Burt
2010-09-06
Fish must orient in three dimensions as they navigate through space, but it is unknown whether they are assisted by a sense of depth. In principle, depth can be estimated directly from hydrostatic pressure, but although teleost fish are exquisitely sensitive to changes in pressure, they appear unable to measure absolute pressure. Teleosts sense changes in pressure via changes in the volume of their gas-filled swim-bladder, but because the amount of gas it contains is varied to regulate buoyancy, this cannot act as a long-term steady reference for inferring absolute pressure. In consequence, it is generally thought that teleosts are unable to sense depth using hydrostatic pressure. Here, we overturn this received wisdom by showing from a theoretical physical perspective that absolute depth could be estimated during fast, steady vertical displacements by combining a measurement of vertical speed with a measurement of the fractional rate of change of swim-bladder volume. This mechanism works even if the amount of gas in the swim-bladder varies, provided that this variation occurs over much longer time scales than changes in volume during displacements. There is therefore no a priori physical justification for assuming that teleost fish cannot sense absolute depth by using hydrostatic pressure cues.
Cardiac T1 Mapping and Extracellular Volume (ECV) in clinical practice: a comprehensive review.
Haaf, Philip; Garg, Pankaj; Messroghli, Daniel R; Broadbent, David A; Greenwood, John P; Plein, Sven
2016-11-30
Cardiovascular Magnetic Resonance is increasingly used to differentiate the aetiology of cardiomyopathies. Late Gadolinium Enhancement (LGE) is the reference standard for non-invasive imaging of myocardial scar and focal fibrosis and is valuable in the differential diagnosis of ischaemic versus non-ischaemic cardiomyopathy. Diffuse fibrosis may go undetected on LGE imaging. Tissue characterisation with parametric mapping methods has the potential to detect and quantify both focal and diffuse alterations in myocardial structure not assessable by LGE. Native and post-contrast T1 mapping in particular has shown promise as a novel biomarker to support diagnostic, therapeutic and prognostic decision making in ischaemic and non-ischaemic cardiomyopathies as well as in patients with acute chest pain syndromes. Furthermore, changes in the myocardium over time may be assessed longitudinally with this non-invasive tissue characterisation method.
Directory of Open Access Journals (Sweden)
Wust Peter
2010-05-01
Full Text Available Abstract Background To assess radiobiological restrictions and tolerance doses as well as other toxic effects derived from repeated applications of single-fraction high dose rate irradiation of small liver volumes in clinical practice. Methods Twenty patients with liver metastases were treated repeatedly (2 - 4 times at identical or intersecting locations by CT-guided interstitial brachytherapy with varying time intervals. Magnetic resonance imaging using the hepatocyte selective contrast media Gd-BOPTA was performed before and after treatment to determine the volume of hepatocyte function loss (called pseudolesion, and the last acquired MRI data set was merged with the dose distributions of all administered brachytherapies. We calculated the BED (biologically equivalent dose for a single dose d = 2 Gy for different α/β values (2, 3, 10, 20, 100 based on the linear-quadratic model and estimated the tolerance dose for liver parenchyma D90 as the BED exposing 90% of the pseudolesion in MRI. Results The tolerance doses D90 after repeated brachytherapy sessions were found between 22 - 24 Gy and proved only slightly dependent on α/β in the clinically relevant range of α/β = 2 - 10 Gy. Variance analysis showed a significant dependency of D90 with respect to the intervals between the first irradiation and the MRI control (p 90 and the pseudolesion's volume. No symptoms of liver dysfunction or other toxic effects such as abscess formation occurred during the follow-up time, neither acute nor on the long-term. Conclusions Inactivation of liver parenchyma occurs at a BED of approx. 22 - 24 Gy corresponding to a single dose of ~10 Gy (α/β ~ 5 Gy. This tolerance dose is consistent with the large potential to treat oligotopic and/or recurrent liver metastases by CT-guided HDR brachytherapy without radiation-induced liver disease (RILD. Repeated small volume irradiation may be applied safely within the limits of this study.
Energy Technology Data Exchange (ETDEWEB)
Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.
2017-06-01
This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.
Energy Technology Data Exchange (ETDEWEB)
Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.
2017-06-01
This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.
Directory of Open Access Journals (Sweden)
D. Deepak
2012-01-01
Full Text Available Abrasive particles in the suspension mixture in an abrasive water suspension jet (AWSJ machining causes acute skin friction effect thereby effectively changing the jet diameter due to wear, which in turn influences jet exit kinetic energy. This results in lowering the life of the jet for effective machining. In consideration of this aspect, the present work examines the effect of inlet pressure on skin friction coefficient and jet exit kinetic energy. It is inferred from the analysis that an increase in inlet pressure causes a significant increase in skin friction coefficient and also results in proportional increase in the exit kinetic energy of the jet. Further, it is revealed from the analysis that an increase volume fraction of abrasive (abrasive concentration in water results in significant decrease in the skin friction coefficient and jet exit kinetic energy.
Directory of Open Access Journals (Sweden)
R. Kandasamy
2017-12-01
Full Text Available The squeezed MHD flow of water based metallic nanoparticles over a porous sensor surface in the presence of heat source has been investigated. The physical significance of the problem is water based on the geometry and the interaction of copper (Cu, aluminum oxide (Al2O3 and SWCNTs. The governing partial differential equations of momentum and energy are converted into ODEs for assured groups of the controlling parameters. The numerical and analytical results of the ODEs are determined utilizing fourth or fifth order Fehlberg method with shooting technique and OHAM and it is analyzed that there is no import difference between them. It is investigated that in squeezing flow phenomena, the effect of nanoparticle volume fraction on SWCNTs–water in the presence of magnetic field with thermal radiation energy plays a dominant role on heat transfer as compared to the other mixtures in the flow regime.
Agustini, S.; Wahyuono, R. A.; Sawitri, D.; Risanti, D. D.
2013-09-01
Since its first development, efforts to improve efficiency of Dye Sensitized Solar Cell (DSSC) are continuously carried out, either through selection of dye materials, the type of semiconductor, counter electrode design or the sandwiched structure. It is widely known that anatase and rutile are phases of TiO2 that often being used for fabrication of DSSC. Rutile is thermodynamically more stable phase having band-gap suitable for absorption of sunlight spectrum. On the other hand, anatase has higher electrical conductivity, capability to adsorp dye as well as higher electron diffusion coefficient than those of rutile. Present research uses mangosteen pericarp and Rhoeo spathacea extracted in ethanol as natural dye containing anthocyanin. These dyes were characterized by using UV-Vis and FTIR, showing that the absorption maxima peaks obtained at 389 nm and 413 nm, for mangosteen and Rhoeo spathacea, respectively. The nano TiO2 was prepared by means of co-precipitation method. The particle size were 9-11 nm and 54.5 nm for anatase and rutile, respectively, according to Scherrer's equation. DSSCs were fabricated in various volume fractions of anatase and rutile TiO2. The fabricated DSSCs were tested under 17 mW/cm2 of solar irradiation. The current-voltage (I-V) characteristic of DSSCs employing 75%: 25% volume fraction of anatase and rutile TiO2 have outstanding result than others. The highest conversion efficiencies of 0.037% and 0.013% are obtained for DSSC employing natural dye extract from mangosteen pericarp and Rhoeo spathacea, respectively.
Li, Geoffrey C; Srivastava, Atul K; Kim, Jonggul; Taylor, Susan S; Veglia, Gianluigi
2015-07-07
Protein kinase A is a prototypical phosphoryl transferase, sharing its catalytic core (PKA-C) with the entire kinase family. PKA-C substrate recognition, active site organization, and product release depend on the enzyme's conformational transitions from the open to the closed state, which regulate its allosteric cooperativity. Here, we used equilibrium nuclear magnetic resonance hydrogen/deuterium (H/D) fractionation factors (φ) to probe the changes in the strength of hydrogen bonds within the kinase upon binding the nucleotide and a pseudosubstrate peptide (PKI5-24). We found that the φ values decrease upon binding both ligands, suggesting that the overall hydrogen bond networks in both the small and large lobes of PKA-C become stronger. However, we observed several important exceptions, with residues displaying higher φ values upon ligand binding. Notably, the changes in φ values are not localized near the ligand binding pockets; rather, they are radiated throughout the entire enzyme. We conclude that, upon ligand and pseudosubstrate binding, the hydrogen bond networks undergo extensive reorganization, revealing that the open-to-closed transitions require global rearrangements of the internal forces that stabilize the enzyme's fold.
Alonzo, M.; Bookhagen, B.; McFadden, J. P.; Sun, A.; Roberts, D. A.
2014-12-01
In urban areas leaf area index (LAI) is a key ecosystem structural attribute with implications for energy and water balance, gas exchange, and anthropogenic energy use. Typically, citywide LAI estimates are extrapolated from those made on forest inventory sample plots through intensive crown measurement and allometric scaling. This is a time- and labor-intensive process yielding coarse spatial resolution results. In this study we generate spatially explicit estimates of LAI using high-point density airborne lidar throughout our study area in downtown Santa Barbara, CA. We implement two theoretically distinct modeling approaches. First, based on hemispherical photography at our 71 field plots, we estimate effective LAI using scan-angle corrected lidar laser penetration metrics (LPM). For our second approach, we adapt existing allometric equations for use with a suite of crown structural metrics (e.g., tree height, crown base height) measured with lidar. This approach allows for estimates of LAI to be made at the individual tree crown scale (ITC). This is important for evaluating fine-scale interactions between canopy and urban surfaces. The LPM method resulted in good agreement with field estimates (r2 = 0.80) and a slope of near unity (β = 0.998) using a model that assumed a spherical leaf angle distribution. Within ITC segments that were automatically delineated using watershed segmentation, lidar estimates of crown structure closely paralleled field measurements (r2=0.87 for crown length). LAI estimates based on the lidar structural variables corresponded well with estimates from field measurements (r2 = 0.84). Agreement between the LPM and allometric lidar methods was also strong across the 71 validation plots (r2 = 0.88) and among 450 sample points (r2 = 0.72) randomly distributed throughout the citywide maps. This is notably higher than the agreement between the hemiphoto and allometric ground-based estimates (r2 = 0.56). The allometric approach generally
Callaghan, David J; Vaziri, Ashkan; Nayeb-Hashemi, Hamid
2006-01-01
The main objective of this study was to evaluate the wear characteristics of fiber-reinforced dental composites. Variables under investigation include the fiber weight percent added to the matrix as well as fiber length. Dental specimens with glass fiber content of 2, 5.1, 5.7, and 7.6 wt% with fiber length of either 1.5 or 3 mm, were prepared by mixing an activated dental resin with commercial glass fibers. The specimens were then tested on a pin on disc setup, where the antagonist disc was manufactured of a similar fiber-reinforced composite with 5.1 wt% fiber and fiber length of 3 mm. The volume loss and coefficient of friction of the specimens was monitored periodically throughout testing. In addition, the wear surfaces of all specimens were evaluated using a scanning electron microscope. The specimens with 5.7 wt% fibers and fiber length of 3 mm performed better in this study compared to all other fiber-reinforced specimens under all load conditions. In fact, this specimen had a comparable wear rate to a particle-filled dental composite. For the fiber lengths considered, increasing the length of the fibers increased the wear resistance of the specimen. The coefficient of friction showed a good correlation with the wear resistance of specimens. Fiber-reinforced composites demonstrated a high resistance to wear and may therefore be advantageous for dental applications, where high wear resistance is essential to functionality.
Directory of Open Access Journals (Sweden)
Manuela Domínguez-Beisiegel
2016-07-01
Full Text Available Inland saline wetlands are complex systems undergoing continuous changes in moisture and salinity and are especially vulnerable to human pressures. Remote sensing is helpful to identify vegetation change in semi-arid wetlands and to assess wetland degradation. Remote sensing-based monitoring requires identification of the spectral characteristics of soils and vegetation and their correspondence with the vegetation cover and soil conditions. We studied the spectral characteristics of soils and vegetation of saline wetlands in Monegros, NE Spain, through field and satellite images. Radiometric and complementary field measurements in two field surveys in 2007 and 2008 were collected in selected sites deemed as representative of different soil moisture, soil color, type of vegetation, and density. Despite the high local variability, we identified good relationships between field spectral data and Quickbird images. A methodology was established for mapping the fraction of vegetation cover in Monegros and other semi-arid areas. Estimating vegetation cover in arid wetlands is conditioned by the soil background and by the occurrence of dry and senescent vegetation accompanying the green component of perennial salt-tolerant plants. Normalized Difference Vegetation Index (NDVI was appropriate to map the distribution of the vegetation cover if the green and yellow-green parts of the plants are considered.
George, David L.; Iverson, Richard M.
2011-01-01
Pore-fluid pressure plays a crucial role in debris flows because it counteracts normal stresses at grain contacts and thereby reduces intergranular friction. Pore-pressure feedback accompanying debris deformation is particularly important during the onset of debrisflow motion, when it can dramatically influence the balance of forces governing downslope acceleration. We consider further effects of this feedback by formulating a new, depth-averaged mathematical model that simulates coupled evolution of granular dilatancy, solid and fluid volume fractions, pore-fluid pressure, and flow depth and velocity during all stages of debris-flow motion. To illustrate implications of the model, we use a finite-volume method to compute one-dimensional motion of a debris flow descending a rigid, uniformly inclined slope, and we compare model predictions with data obtained in large-scale experiments at the USGS debris-flow flume. Predictions for the first 1 s of motion show that increasing pore pressures (due to debris contraction) cause liquefaction that enhances flow acceleration. As acceleration continues, however, debris dilation causes dissipation of pore pressures, and this dissipation helps stabilize debris-flow motion. Our numerical predictions of this process match experimental data reasonably well, but predictions might be improved by accounting for the effects of grain-size segregation.
Morse, A; Yu, N Y C; Peacock, L; Mikulec, K; Kramer, I; Kneissel, M; McDonald, M M; Little, D G
2015-02-01
Sclerostin deficiency, via genetic knockout or anti-Sclerostin antibody treatment, has been shown to cause increased bone volume, density and strength of calluses following endochondral bone healing. However, there is limited data on the effect of Sclerostin deficiency on the formative early stage of fibrocartilage (non-bony tissue) formation and removal. In this study we extensively investigate the early fibrocartilage callus. Closed tibial fractures were performed on Sost(-/-) mice and age-matched wild type (C57Bl/6J) controls and assessed at multiple early time points (7, 10 and 14days), as well as at 28days post-fracture after bony union. External fixation was utilized, avoiding internal pinning and minimizing differences in stability stiffness, a variable that has confounded previous research in this area. Normal endochondral ossification progressed in wild type and Sost(-/-) mice with equivalent volumes of fibrocartilage formed at early day 7 and day 10 time points, and bony union in both genotypes by day 28. There were no significant differences in rate of bony union; however there were significant increases in fibrocartilage removal from the Sost(-/-) fracture calluses at day 14 suggesting earlier progression of endochondral healing. Earlier bone formation was seen in Sost(-/-) calluses over wild type with greater bone volume at day 10 (221%, pfractured Sost(-/-) tibiae was greater than that that of wild type fractured tibiae. In summary, bony union was not altered by Sclerostin deficiency in externally-fixed closed tibial fractures, but fibrocartilage removal was enhanced and the resultant united bony calluses had increased bone fraction and increased strength. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Yoo, Yeon Hwa; Kim, Hak Sun; Lee, Young Han [Dept. of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); and others
2015-10-15
To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2{sup *} estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2{sup *}-corrected two-echo Dixon or T2{sup *}-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard. Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2{sup *}-corrected Dixon technique with two (non-T2{sup *}-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences. A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 ± 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (p < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (p < 0.001), as compared with two- or three-echo methods. T2{sup *}-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification.
Fractional and noncommutative spacetimes
Arzano, M.|info:eu-repo/dai/nl/32616443X; Calcagni, M.; Oriti, D.; Scalisi, M.
2011-01-01
We establish a mapping between fractional and noncommutative spacetimes in configuration space. Depending on the scale at which the relation is considered, there arise two possibilities. For a fractional spacetime with log-oscillatory measure, the effective measure near the fundamental scale
Energy Technology Data Exchange (ETDEWEB)
Jing, Hao [Department of Radiation Oncology, Cancer Hospital and Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China); Wang, Shu-Lian, E-mail: wsl20040118@yahoo.com [Department of Radiation Oncology, Cancer Hospital and Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China); Li, Jing; Xue, Mei; Xiong, Zu-Kun [Department of Radiology, Cancer Hospital and Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China); Jin, Jing; Wang, Wei-Hu; Song, Yong-Wen; Liu, Yue-Ping; Ren, Hua; Fang, Hui; Yu, Zi-Hao; Liu, Xin-Fan [Department of Radiation Oncology, Cancer Hospital and Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China); Li, Ye-Xiong, E-mail: yexiong12@163.com [Department of Radiation Oncology, Cancer Hospital and Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China)
2015-10-01
Purpose: To map the location of metastatic supraclavicular (SCV) lymph nodes (LNMs) in breast cancer patients with SCV node involvement and determine whether and where the radiation therapy clinical target volume (CTV) of this region could be modified in high-risk subsets. Methods and Materials: Fifty-five patients with metastatic SCV LNMs were eligible for geographic mapping and atlas coverage analysis. All LNMs and their epicenters were registered proportionally by referencing the surrounding landmarks onto simulation computed tomography images of a standard patient. CTVs based on selected SCV atlases, including the one by the Radiation Therapy Oncology Group (RTOG) were contoured. A modified SCV CTV was tried and shown to have better involved-node coverage and thus theoretically improved prophylaxis in this setting. Results: A total of 50 (91%) and 45 (81.8%) patients had LNMs in the medial and lateral SCV subregions, respectively. Also, 36 patients (65.5%) had LNMs located at the junction of the jugular-subclavian veins. All nodes were covered in only 25.5% to 41.8% of patients by different atlases. The RTOG atlas covered all nodes in 25.5% of patients. Stratified by the nodes in all the patients as a whole, 49.2% to 81.3% were covered, and the RTOG atlas covered 62.6%. The lateral and posterior borders were the most overlooked locations. Modification by extending the borders to natural anatomic barriers allowed the new CTV to cover all the nodes in 81.8% of patients and encompass 96.1% of all the nodes. Conclusions: According to the distribution of SCV LNMs, the extent of existing atlases might not be adequate for potential metastatic sites in certain groups of patients. The extension of the lateral and posterior CTV borders in high-risk or recurrent patients might be a reasonable approach for increasing coverage. However, additional data in more homogeneous populations with localized disease are needed before routine application.
Schelbert, Erik B; Piehler, Kayla M; Zareba, Karolina M; Moon, James C; Ugander, Martin; Messroghli, Daniel R; Valeti, Uma S; Chang, Chung-Chou H; Shroff, Sanjeev G; Diez, Javier; Miller, Christopher A; Schmitt, Matthias; Kellman, Peter; Butler, Javed; Gheorghiade, Mihai; Wong, Timothy C
2015-12-18
Myocardial fibrosis (MF) in noninfarcted myocardium may be an interstitial disease pathway that confers vulnerability to hospitalization for heart failure, death, or both across the spectrum of heart failure and ejection fraction. Hospitalization for heart failure is an epidemic that is difficult to predict and prevent and requires potential therapeutic targets associated with outcomes. We quantified MF with cardiovascular magnetic resonance extracellular volume fraction (ECV) measures in 1172 consecutive patients without amyloidosis or hypertrophic or stress cardiomyopathy and assessed associations with outcomes using Cox regression. ECV ranged from 16.6% to 47.8%. Over a median of 1.7 years, 111 patients experienced events after cardiovascular magnetic resonance, 55 had hospitalization for heart failure events, and there were 74 deaths. ECV was more strongly associated with outcomes than "nonischemic" MF observed with late gadolinium enhancement, thus ECV quantified MF in multivariable models. Adjusting for age, sex, renal function, myocardial infarction size, ejection fraction, hospitalization status, and heart failure stage, higher ECV was associated with hospitalization for heart failure (hazard ratio 1.77; 95% CI 1.32 to 2.36 for every 5% increase in ECV), death (hazard ratio 1.87 95% CI 1.45 to 2.40) or both (hazard ratio 1.85, 95% CI 1.50 to 2.27). ECV improved classification of persons at risk and improved model discrimination for outcomes (eg, hospitalization for heart failure: continuous net reclassification improvement 0.33, 95% CI 0.05 to 0.66; P=0.02; 0.16, 95% CI 0.01 to 0.33; P=0.02; integrated discrimination improvement 0.037, 95% CI 0.008 to 0.073; Pheart failure, death, or both. MF may represent a principal phenotype of cardiac vulnerability that improves risk stratification. Because MF can be reversible, cells and enzymes regulating collagen could be potential therapeutic targets. © 2015 The Authors. Published on behalf of the American Heart
Kinzl, M; Boger, A; Zysset, P K; Pahr, D H
2011-10-13
Vertebroplasty forms a porous PMMA/bone composite which was shown to be weaker and less stiff than pure PMMA. It is not known what determines the mechanical properties of such composites in detail. This study investigated the effects of bone volume fraction (BV/TV), cement porosity (PV/(TV-BV), PV…pore volume) and cement stiffness. Nine human vertebral bodies were augmented with either standard or low-modulus PMMA cement and scanned with a HR-pQCT system before and after augmentation. Fourteen cylindrical PMMA/bone biopsies were extracted from the augmented region, scanned with a micro-CT system and tested in compression until failure. Micro-finite element (FE) models of the complete biopsies, of the trabecular bone alone as well as of the porous cement alone were generated from CT images to gain more insight into the role of bone and pores. PV/(TV-BV) and experimental moduli of standard/low-modulus cement (R(2)=0.91/0.98) as well as PV/(TV-BV) and yield stresses (R(2)=0.92/0.83) were highly correlated. No correlation between BV/TV (ranging from 0.057 to 0.138) and elastic moduli was observed (R(2)< 0.05). Interestingly, the micro-FE models of the porous cement alone reproduced the experimental elastic moduli of the standard/low-modulus cement biopsies (R(2)=0.75/0.76) more accurately than the models with bone (R(2)=0.58/0.31). In conclusion, the mechanical properties of the biopsies were mainly determined by the cement porosity and the cement material properties. The study showed that bone tissue inside the biopsies was mechanically "switched off" such that load was carried essentially by the porous PMMA. Copyright © 2011 Elsevier Ltd. All rights reserved.
Jin, Hee; Jeon, Seulgi; Kang, Ga-Young; Lee, Hae-June; Cho, Jaeho; Lee, Yun-Sil
2017-02-01
The molecular effects of focal exposure of limited lung volumes to high-dose per fraction irradiation (HDFR) such as stereotactic body radiotherapy (SBRT) have not been fully characterized. In this study, we used such an irradiation system and identified the genes and proteins after HDFR to mouse lung, similar to those associated with human therapy. High focal radiation (90 Gy) was applied to a 3-mm volume of the left lung of C57BL6 mice using a small-animal stereotactic irradiator. As well as histological examination for lungs, a cDNA micro array using irradiated lung tissues and a protein array of sera were performed until 4 weeks after irradiation, and radiation-responsive genes and proteins were identified. For comparison, the long-term effects (12 months) of 20 Gy radiation wide-field dose to the left lung were also investigated. The genes ermap, epb4.2, cd200r3 (up regulation) and krt15, hoxc4, gdf2, cst9, cidec, and bnc1 (down-regulation) and the proteins of AIF, laminin, bNOS, HSP27, β-amyloid (upregulation), and calponin (downregulation) were identified as being responsive to 90 Gy HDFR. The gdf2, cst9, and cidec genes also responded to 20 Gy, suggesting that they are universal responsive genes in irradiated lungs. No universal proteins were identified in both 90 Gy and 20 Gy. Calponin, which was downregulated in protein antibody array analysis, showed a similar pattern in microarray data, suggesting a possible HDFR responsive serum biomarker that reflects gene alteration of irradiated lung tissue. These genes and proteins also responded to the lower doses of 20 Gy and 50 Gy HDFR. These results suggest that identified candidate genes and proteins are HDFR-specifically expressed in lung damage induced by HDFR relevant to SBRT in humans.
Zhang, Guifeng; Wei, Zhongxin; Chen, Biqiang; Chen, Bo
2017-12-01
Features of transient liquid phase (TLP) bondability of high-volume fraction (70 vol.%) SiC particle-reinforced A356 composite for popular Cu interlayer were investigated. Although Cu foil was melted, molten Cu was completely expulsed, indicating that the numerous SiC particles significantly deteriorated wettability not only at particle/braze metal (P/M) interface, but also at the matrix/braze metal (M/M) interface. For the reason of poor wettability at P/M interface, a model showing there is a "window period" for actual wetting reaction (allowing liquid phase to be in contact with surficial SiC particles) much shorter than nominal isothermal solidification time during TLP bonding of the composite containing sintered ceramic preform was proposed. For the poor wettability at M/M interface, both size effect of too small matrix unit (2 20 μm) and restraint effect of the rigid porous ceramic preform on suppressing oxide film crack on the small matrix unit surface were proposed. Thus, chemical route to disrupt oxide film on the small matrix unit surface should be preferred in braze composition design. For example, Al-27Cu-5Si-2Mg-1Ti braze was developed by co-addition of Mg and Ti to improve wettability and to in situ reinforce bond seam, respectively; Ti also could remedy Mg loss for improving wettability.
DeKoninck, Philip; Jimenez, Julio; Russo, Francesca M; Hodges, Ryan; Gratacós, Eduard; Deprest, Jan
2014-10-01
The objective of this study is to evaluate whether assessment pulmonary vascular reactivity in response to maternal hyperoxygenation using fractional moving blood volume (FMBV) is associated with lesser variability between individual measurements than what is observed with direct Doppler measurements. Forty-five measurements were performed in 15 singleton fetuses with normal lung development at three time points in the latter half of pregnancy (range: 25.9-36.7 weeks). We further evaluated five fetuses with severe congenital diaphragmatic hernia. Lung perfusion was assessed using power Doppler ultrasound, and images were stored for offline FMBV calculation, both at base line and during oxygen administration (9 L/min for 10 min). The proportionate difference between both measurements is further referred to as deltaFMBV. Overall, 91% of images were of sufficient quality for further analysis. There was no correlation between pulmonary reactivity to oxygen (deltaFMBV) and gestational age in controls (12.9 ± 32.1%). Moreover, deltaFMBV showed large variability between subjects, as well as within the same fetus throughout gestation. We observed good intraobserver (0.88; 0.84) and interobserver (0.88; 0.77) reproducibility for both controls and congenital diaphragmatic hernia, respectively (intraclass correlation coefficients). Despite being a reproducible method to study the lung vasculature, the large variability of FMBV following hyperoxygenation limits its clinical translation. © 2014 John Wiley & Sons, Ltd.
Russin, W. R.
1974-01-01
Tests were conducted to determine the performance of a hydrogen burner used to produce a test gas that simulates air entering a scramjet combustor at various flight conditions. The test gas simulates air in that it duplicates the total temperature, total pressure, and the volume fraction of oxygen of air at flight conditions. The main objective of the tests was to determine the performance of the burner as a function of the effective exhaust port area. The conclusions were: (1) pressure oscillations of the chugging type were reduced in amplitude to plus or minus 2 percent of the mean pressure level by proper sizing of hydrogen, oxygen, and air injector flow areas; (2) combustion efficiency remained essentially constant as the exhaust port area was increased by a factor of 3.4; (3) the mean total temperature determined from integrating the exit radial gas property profiles was within plus or minus 5 percent of the theoretical bulk total temperature; (4) the measured exit total temperature profile had a local peak temperature more than 30 percent greater than the theoretical bulk total temperature; and (5) measured heat transfer to the burner liner was 75 percent of that predicted by theory based on a flat radial temperature profile.
Park, Sang Hoo; Im, Min Ji; Eom, Sang-Yong; Hahn, Youn-Soo
2017-09-01
Airway pathology in children with atopic asthma can be reflected by the concave shape of the maximal expiratory flow-volume (MEFV) curve and high fractional exhaled nitric oxide (FeNO) values. We evaluated the capacity of the curvilinearity of the MEFV curve, FeNO, and their combination to distinguish subjects with atopic asthma from healthy individuals. FeNO and angle β, which characterizes the general configuration of the MEFV curve, were determined in 119 steroid-naïve individuals with atopic asthma aged 8 to 16 years, and in 92 age-matched healthy controls. Receiver operating characteristic (ROC) curve analyses were performed to determine the cutoff points of FeNO and angle β that provided the best combination of sensitivity and specificity for asthma detection. Asthmatic patients had a significantly smaller angle β and higher FeNO compared with healthy controls (both, Pcurve for the combination of angle β and FeNO improved to 0.91 (95% confidence interval [CI], 0.87-0.95) from 0.80 (95% CI, 0.75-0.86; Pcurve and FeNO is a useful tool to differentiate between children with and without atopic asthma.
Wang, S; Huang, L J; Geng, L; Scarpa, F; Jiao, Y; Peng, H X
2017-01-17
We present a new class of TiBw/Ti6Al4V composites with a network reinforcement architecture that exhibits a significant creep resistance compared to monolithic Ti6Al4V alloys. Creep tests performed at temperatures between 773 K and 923 K and stress range of 100 MPa-300 MPa indicate both a significant improvement of the composites creep resistance due to the network architecture made by the TiB whiskers (TiBw), and a decrease of the steady-state creep rates by augmenting the local volume fractions of TiBw in the network region. The deformation behavior is driven by a diffusion-controlled dislocation climb process. Moreover, the activation energies of these composites are significantly higher than that of Ti6Al4V alloys, indicating a higher creep resistance. The increase of the activation energy can be attributed to the TiBw architecture that severely impedes the movements of dislocation and grain boundary sliding and provides a tailoring of the stress transfer. These micromechanical mechanisms lead to a remarkable improvement of the creep resistance of these networked TiBw/Ti6Al4V composites featuring the special networked architecture.
Wang, S.; Huang, L. J.; Geng, L.; Scarpa, F.; Jiao, Y.; Peng, H. X.
2017-01-01
We present a new class of TiBw/Ti6Al4V composites with a network reinforcement architecture that exhibits a significant creep resistance compared to monolithic Ti6Al4V alloys. Creep tests performed at temperatures between 773 K and 923 K and stress range of 100 MPa-300 MPa indicate both a significant improvement of the composites creep resistance due to the network architecture made by the TiB whiskers (TiBw), and a decrease of the steady-state creep rates by augmenting the local volume fractions of TiBw in the network region. The deformation behavior is driven by a diffusion-controlled dislocation climb process. Moreover, the activation energies of these composites are significantly higher than that of Ti6Al4V alloys, indicating a higher creep resistance. The increase of the activation energy can be attributed to the TiBw architecture that severely impedes the movements of dislocation and grain boundary sliding and provides a tailoring of the stress transfer. These micromechanical mechanisms lead to a remarkable improvement of the creep resistance of these networked TiBw/Ti6Al4V composites featuring the special networked architecture.
Chaos in discrete fractional difference equations
Indian Academy of Sciences (India)
In the present paper, the chaotic behaviour of fractional difference equations for the tent map, Gauss map and 2x(mod 1) map are studied numerically. We analyse the chaotic behaviour of these fractional difference equations and compare them with their integer counterparts. It is observed that fractional difference equations ...
Energy Technology Data Exchange (ETDEWEB)
Amiot, L.W.; Lima, R.J.; Scholbrock, S.D.; Shelman, C.B.; Wehman, R.H.
1979-06-01
Volume I of An Interim Report on the Development and Application of Environmental Mapped Data Digitization, Encoding, Analysis, and Display Software for the ALICE System provided an overall description of the software developed for the ALICE System and presented an example of its application. The scope of the information presented in Volume I was directed both to the users and developers of digitization, encoding, analysis, and display software. Volume II presents information which is directly related to the actual computer code and operational characteristics (keys and subroutines) of the software. Volume II will be of more interest to developers of software than to users of the software. However, developers of software should be aware that the code developed for the ALICE System operates in an environment where much of the peripheral hardware to the PDP-10 is ANL/AMD built. For this reason, portions of the code may have to be modified for implementation on other computer system configurations. 11 tables.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 1. Continued Fractions for e. Shailesh A Shirali. General Article Volume 5 Issue 1 January 2000 pp 14-28. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/005/01/0014-0028. Author Affiliations.
Ohlerth, Stefanie; Bley, Carla Rohrer; Laluhová, Dagmar; Roos, Malgorzata; Kaser-Hotz, Barbara
2010-10-01
Radiation therapy does not only target tumour cells but also affects tumour vascularity. In the present study, changes in tumour vascularity and blood volume were investigated in five grade 1 oral fibrosarcomas, eight other sarcomas (non-oral soft tissue and bone sarcomas) and 12 squamous cell carcinomas in dogs during fractionated radiation therapy (total dose, 45-56 Gy). Contrast-enhanced power Doppler ultrasound was performed before fraction 1, 3, 6, 8, 10, 12, 14 and 15 or 16 (sarcomas) or 17 (squamous cell carcinomas). Prior to treatment, median vascularity and blood volume were significantly higher in squamous cell carcinomas (P=0.0005 and 0.001), whereas measurements did not differ between oral fibrosarcomas and other sarcomas (P=0.88 and 0.999). During the course of radiation therapy, only small, non-significant changes in vascularity and blood volume were observed in all three tumour histology groups (P=0.08 and P=0.213), whereas median tumour volume significantly decreased until the end of treatment (P=0.04 for fibrosarcomas and other sarcomas, P=0.008 for squamous cell carcinomas). It appeared that there was a proportional decrease in tumour volume, vascularity and blood volume. Doppler measurements did not predict progression free interval or survival in any of the three tumour groups (P=0.06-0.86). However, the number of tumours investigated was small and therefore, the results can only be considered preliminary. Copyright © 2009 Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Eble, Michael J. [Dept. of Radiotherapy, RWTH Aachen (Germany); Pinkawa, Michael; Piroth, Marc D.; Fischedick, Karin; Holy, Richard; Klotz, Jens; Nussen, Sandra; Krenkel, Barbara
2009-11-15
Purpose: to evaluate the impact of the clinical target volume (CTV) and fraction dose on quality of life (QoL) after external-beam radiotherapy (EBRT) for prostate cancer. Patients and methods: a group of 283 patients has been surveyed prospectively before, at the last day, at a median time of 2 months and 15 months after EBRT (70.2-72 Gy) using a validated questionnaire (Expanded Prostate Cancer Index Composite). FBRT of prostate alone (P, n = 70) versus prostate with seminal vesicles (PS, n = 213) was compared. Differences of fraction doses (1.8 Gy, n = 80, vs. 2.0 Gy, n = 69) have been evaluated in the patient group receiving a total dose of 72 Gy. Results: significantly higher bladder and rectum volumes were found at all dose levels for the patients with PS versus P within the CTV (p < 0.001). Similar volumes resulted in the groups with different fraction doses. Paradoxically, bowel function scores decreased significantly less 2 and 15 months after EBRT of PS versus P. 2 months after EBRT, patients with a fraction dose of 2.0 Gy versus 1.8 Gy reported pain with urination ({>=} once a day in 12% vs. 3%; p = 0.04) and painful bowel movements ({>=} rarely in 46% vs. 29%; p = 0.05) more frequently. No long-term differences were found. Conclusion: the risk of adverse QoL changes after EBRT for prostate cancer cannot be derived from the dose-volume histogram alone. Seminal vesicles can be included in the CTV up to a moderate total dose without adverse effects on QoL. Apart from a longer recovery period, higher fraction doses were not associated with higher toxicity. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Henzel, Martin; Engenhart-Cabillic, Rita [Dept. of Radiation Oncology, Philipps Univ. Marburg (Germany); Hamm, Klaus; Surber, Gunnar; Kleinert, Gabriele [Dept. of Stereotactic Neurosurgery and Radiosurgery, HELIOS Klinikum, Erfurt (Germany); Sitter, Helmut [Dept. of Theoretical Surgery, Philipps Univ. Marburg (Germany); Gross, Markus W. [Dept. of Radiation Oncology, Philipps Univ. Marburg (Germany); Dept. of Radio-Oncology, Univ. Hospital of Basel (Switzerland)
2009-09-15
Background and purpose: stereotactic radiosurgery (SRS) and also fractionated stereotactic radiotherapy (SRT) offer high local control (LC) rates (> 90%). This study aimed to evaluate three-dimensional (3-D) tumor volume (TV) shrinkage and to assess quality of life (QoL) after SRS/SRT. Patients and methods: from 1999 to 2005, 35/74 patients were treated with SRS, and 39/74 with SRT. Median age was 60 years. Treatment was delivered by a linear accelerator. Median single dose was 13 Gy (SRS) or 54 Gy (SRT). Patients were followed up {>=} 12 months after SRS/SRT. LC and toxicity were evaluated by clinical examinations and magnetic resonance imaging. 3-D TV shrinkage was evaluated with the planning system. QoL was assessed using the questionnaire Short Form-36. Results: Median follow-up was 50/36 months (SRS/SRT). Actuarial 5-year freedom from progression/overall survival was 88.1%/100% (SRS), and 87.5%/87.2% (SRT). TV shrinkage was 15.1%/40.7% (SRS/SRT; p = 0.01). Single dose (< 13 Gy) was the only determinant factor for TV shrinkage after SRS (p = 0.001). Age, gender, initial TV, and previous operations did not affect TV shrinkage. Acute or late toxicity ({>=} grade 3) was never seen. Concerning QoL, no significant differences were observed after SRS/SRT. Previous operations and gender did not affect QoL (p > 0.05). Compared with the German normal population, patients had worse values for all domains except for mental health. Conclusion: TV shrinkage was significantly higher after SRT than after SRS. Main symptoms were not affected by SRS/SRT. Retrospectively, QoL was neither affected by SRS nor by SRT. (orig.)
National Oceanic and Atmospheric Administration, Department of Commerce — Currently, the most widely used approach to sensitive environment mapping in the United States is the NOAA Environmental Sensitivity Index (ESI). This approach...
National Oceanic and Atmospheric Administration, Department of Commerce — This data set comprises the Environmental Sensitivity Index (ESI) maps for the shoreline of South Carolina. ESI data characterize coastal environments and wildlife...
National Oceanic and Atmospheric Administration, Department of Commerce — This data set comprises the Environmental Sensitivity Index (ESI) maps for the shoreline of North Carolina. ESI data characterize coastal environments and wildlife...
Maffessanti, Francesco; Muraru, Denisa; Esposito, Roberta; Gripari, Paola; Ermacora, Davide; Santoro, Ciro; Tamborini, Gloria; Galderisi, Maurizio; Pepi, Mauro; Badano, Luigi P
2013-09-01
Right ventricular (RV) volumes and ejection fraction (EF) vary significantly with demographic and anthropometric factors and are associated with poor prognosis in several cardiovascular diseases. This multicenter study was designed to (1) establish the reference values for RV volumes and EF using transthoracic three-dimensional (3D) echocardiography; (2) investigate the influence of age, sex, and body size on RV anatomy; (3) develop normative equations. RV volumes (end-diastolic volume and end-systolic volume), stroke volume, and EF were measured by 3D echocardiography in 540 healthy adult volunteers, prospectively enrolled, evenly distributed across age and sex. The relation of age, sex, and body size parameters was investigated using bivariate and multiple linear regression. Analysis was feasible in 507 (94%) subjects (260 women; age, 45 ± 16 years; range, 18-90). Age, sex, height, and weight significantly influenced RV volumes and EF. Sex effect was significant (Pallometric indexing for age, sex, and body size resulted in no significant residual correlation between RV measures and height or weight. The presented normative ranges and equations could help standardize the 3D echocardiography assessment of RV volumes and function in clinical practice, considering the effects of age, sex, and body size.
Edelman, Mark
2015-07-01
In this paper, we consider a simple general form of a deterministic system with power-law memory whose state can be described by one variable and evolution by a generating function. A new value of the system's variable is a total (a convolution) of the generating functions of all previous values of the variable with weights, which are powers of the time passed. In discrete cases, these systems can be described by difference equations in which a fractional difference on the left hand side is equal to a total (also a convolution) of the generating functions of all previous values of the system's variable with the fractional Eulerian number weights on the right hand side. In the continuous limit, the considered systems can be described by the Grünvald-Letnikov fractional differential equations, which are equivalent to the Volterra integral equations of the second kind. New properties of the fractional Eulerian numbers and possible applications of the results are discussed.
Energy Technology Data Exchange (ETDEWEB)
Peixoto, Philippe Netto Belache
2016-07-01
This study presents a methodology based on the principles of gamma ray attenuation to identify volume fractions in biphasic systems composed of oil-gas-water and gas which are found in the offshore oil industry. This methodology is based on the acknowledgment counts per second on the photopeak energy using a detection system composed of a NaI (Tl) detector, a source of {sup 137}Cs without collimation positioned at 180 ° relative to the detector on a smooth stratified flow regime. The mathematical modeling for computational simulation using the code MCNP-X was performed using the experimental measurements of the detector characteristics (energy resolution and efficiency), characteristics of the material water and oil (density and coefficient attenuation) and measurement of the volume fractions. To predict these fractions were used artificial neural networks (ANNs), and to obtain an adequate training the ANNs for the prediction of volume fractions were simulated a larger number of volume fractions in MCNP-X. The experimental data were used in the set data necessary for validation of ANNs and the data generated using the computer code MCNP-X were used in training and test sets of the ANNs. Were used ANNs of type feed-forward Multilayer Perceptron (MLP) and analyzed two functions of training, Levenberg-Marquardt (LM) and gradient descent with momentum (GDM), both using the Backpropagation training algorithm. The ANNs identified correctly the volume fractions of the multiphase system with mean relative errors lower than 1.21 %, enabling the application of this methodology for this purpose. (author)
2005-09-01
The Long-Term Plan for Concrete Pavement Research and Technology (CP Road Map) is a holistic, strategic : plan for concrete pavement research and technology transfer. The CP Road Map is a 7- to 10-year plan that : includes 12 distinct but integrated ...
Mendlovic, D; Ozaktas, H M; Lohmann, A W
1995-01-10
Recently, optical interpretations of the fractional-Fourier-transform operator have been introduced. On the basis of this operator the fractional correlation operator is defined in two different ways that are both consistent with the definition of conventional correlation. Fractional correlation is not always a shift-invariant operation. This property leads to some new applications for fractional correlation as shift-variant image detection. A bulk-optics implementation of fractional correlation is suggested and demonstrated with computer simulations.
Gloger, Oliver; Tönnies, Klaus; Mensel, Birger; Völzke, Henry
2015-11-01
In epidemiological studies as well as in clinical practice the amount of produced medical image data strongly increased in the last decade. In this context organ segmentation in MR volume data gained increasing attention for medical applications. Especially in large-scale population-based studies organ volumetry is highly relevant requiring exact organ segmentation. Since manual segmentation is time-consuming and prone to reader variability, large-scale studies need automatized methods to perform organ segmentation. Fully automatic organ segmentation in native MR image data has proven to be a very challenging task. Imaging artifacts as well as inter- and intrasubject MR-intensity differences complicate the application of supervised learning strategies. Thus, we propose a modularized framework of a two-stepped probabilistic approach that generates subject-specific probability maps for renal parenchyma tissue, which are refined subsequently by using several, extended segmentation strategies. We present a three class-based support vector machine recognition system that incorporates Fourier descriptors as shape features to recognize and segment characteristic parenchyma parts. Probabilistic methods use the segmented characteristic parenchyma parts to generate high quality subject-specific parenchyma probability maps. Several refinement strategies including a final shape-based 3D level set segmentation technique are used in subsequent processing modules to segment renal parenchyma. Furthermore, our framework recognizes and excludes renal cysts from parenchymal volume, which is important to analyze renal functions. Volume errors and Dice coefficients show that our presented framework outperforms existing approaches.
National Oceanic and Atmospheric Administration, Department of Commerce — This data set comprises the Environmental Sensitivity Index (ESI) maps in Portable Document Format (.PDF) for the shoreline of lower West Peninsular Florida (to...
Huang, Shengli; Ramirez, Carlos; Conway, Scott; Kennedy, Kama; Kohler, Tanya; Liu, Jinxun
2016-01-01
High-resolution site index (SI) and mean annual increment (MAI) maps are desired for local forest management. We integrated field inventory, Landsat, and ecological variables to produce 30 m SI and MAI maps for the Tahoe National Forest (TNF) where different tree species coexist. We converted species-specific SI using adjustment factors. Then, the SI map was produced by (i) intensifying plots to expand the training sets to more climatic, topographic, soil, and forest reflective classes, (ii) using results from a stepwise regression to enable a weighted imputation that minimized the effects of outlier plots within classes, and (iii) local interpolation and strata median filling to assign values to pixels without direct imputations. The SI (reference age is 50 years) map had an R2 of 0.7637, a root-mean-square error (RMSE) of 3.60, and a mean absolute error (MAE) of 3.07 m. The MAI map was similarly produced with an R2 of 0.6882, an RMSE of 1.73, and a MAE of 1.20 m3·ha−1·year−1. Spatial patterns and trends of SI and MAI were analyzed to be related to elevation, aspect, slope, soil productivity, and forest type. The 30 m SI and MAI maps can be used to support decisions on fire, plantation, biodiversity, and carbon.
Directory of Open Access Journals (Sweden)
Sebastian Wilhelm
2014-08-01
Full Text Available The forests of the Russian Taiga can be described as an enormous biomass and carbon reservoir. Therefore, they are of utmost importance for the global carbon cycle. Large-area forest inventories in these mostly remote regions are associated with logistical problems and high financial efforts. Remotely-sensed data from satellite platforms may have the capability to provide such huge amounts of information. This study presents an application-oriented approach to derive aboveground growing stock volume (GSV maps using the annual large-area L-band backscatter mosaics provided by the Japan Aerospace Exploration Agency (JAXA. Furthermore, a multi-temporal map has been created to improve GSV estimation accuracy. Based on information from Russian forest inventory data, the maps were generated using the machine learning algorithm, RandomForest. The results showed the high potential of this method for an operational, large-scale and high-resolution biomass estimation over boreal forests. An RMSE from 55.2 to 63.3 m3/ha could be obtained for the annual maps. Using the multi-temporal approach, the error could be slightly reduced to 54.4 m3/ha.
Energy Technology Data Exchange (ETDEWEB)
Tang, Robert Y., E-mail: rx-tang@laurentian.ca [Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada); McDonald, Nancy, E-mail: mcdnancye@gmail.com; Laamanen, Curtis, E-mail: cx-laamanen@laurentian.ca [Department of Physics, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada); LeClair, Robert J., E-mail: rleclair@laurentian.ca [Department of Physics, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada and Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada)
2014-11-01
Purpose: To develop a method to estimate the mean fractional volume of fat (ν{sup ¯}{sub fat}) within a region of interest (ROI) of a tissue sample for wide-angle x-ray scatter (WAXS) applications. A scatter signal from the ROI was obtained and use of ν{sup ¯}{sub fat} in a WAXS fat subtraction model provided a way to estimate the differential linear scattering coefficient μ{sub s} of the remaining fatless tissue. Methods: The efficacy of the method was tested using animal tissue from a local butcher shop. Formalin fixed samples, 5 mm in diameter 4 mm thick, were prepared. The two main tissue types were fat and meat (fibrous). Pure as well as composite samples consisting of a mixture of the two tissue types were analyzed. For the latter samples, ν{sub fat} for the tissue columns of interest were extracted from corresponding pixels in CCD digital x-ray images using a calibration curve. The means ν{sup ¯}{sub fat} were then calculated for use in a WAXS fat subtraction model. For the WAXS measurements, the samples were interrogated with a 2.7 mm diameter 50 kV beam and the 6° scattered photons were detected with a CdTe detector subtending a solid angle of 7.75 × 10{sup −5} sr. Using the scatter spectrum, an estimate of the incident spectrum, and a scatter model, μ{sub s} was determined for the tissue in the ROI. For the composite samples, a WAXS fat subtraction model was used to estimate the μ{sub s} of the fibrous tissue in the ROI. This signal was compared to μ{sub s} of fibrous tissue obtained using a pure fibrous sample. Results: For chicken and beef composites, ν{sup ¯}{sub fat}=0.33±0.05 and 0.32 ± 0.05, respectively. The subtractions of these fat components from the WAXS composite signals provided estimates of μ{sub s} for chicken and beef fibrous tissue. The differences between the estimates and μ{sub s} of fibrous obtained with a pure sample were calculated as a function of the momentum transfer x. A t-test showed that the mean of the
Povstenko, Yuriy
2015-01-01
This book is devoted to fractional thermoelasticity, i.e. thermoelasticity based on the heat conduction equation with differential operators of fractional order. Readers will discover how time-fractional differential operators describe memory effects and space-fractional differential operators deal with the long-range interaction. Fractional calculus, generalized Fourier law, axisymmetric and central symmetric problems and many relevant equations are featured in the book. The latest developments in the field are included and the reader is brought up to date with current research. The book contains a large number of figures, to show the characteristic features of temperature and stress distributions and to represent the whole spectrum of order of fractional operators. This work presents a picture of the state-of-the-art of fractional thermoelasticity and is suitable for specialists in applied mathematics, physics, geophysics, elasticity, thermoelasticity and engineering sciences. Corresponding sections of ...
Lam, Carolyn S. P.; Rienstra, Michiel; Tay, Wan-Ting; Liu, Licette C. Y.; Hummel, Yoran M.; van der Meer, Peter; de Boer, Rudolf A.; Van Gelder, Isabelle C.; van Veldhuisen, Dirk J.; Voors, Adriaan A.; Hoendermis, Elke S.
OBJECTIVES This study sought to study the association of atrial fibrillation (AF) with exercise capacity, left ventricular filling pressure, natriuretic peptides, and left atrial size in heart failure with preserved ejection fraction (HFpEF). BACKGROUND The diagnosis of HFpEF in patients with AF
Energy Technology Data Exchange (ETDEWEB)
Yang Haihua [Department of Radiation Oncology, Taizhou Hospital, Wenzhou Medical College, Taizhou, Zhejiang (China); Hu Wei, E-mail: huw@tzhospital.com [Department of Radiation Oncology, Taizhou Hospital, Wenzhou Medical College, Taizhou, Zhejiang (China); Ding Weijun; Shan Guoping; Wang Wei; Yu Changhui; Wang Biyun; Shao Minghai; Wang Jianhua; Yang Weifang [Department of Radiation Oncology, Taizhou Hospital, Wenzhou Medical College, Taizhou, Zhejiang (China)
2012-07-01
To quantify changes of the transverse diameter and volume and dosimetry, and to illustrate the inferiority of non-replanning during intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) patients. Fifty-three NPC patients who received IMRT in 33 fractions were enrolled in this prospective trial. Before the 25th fraction, a new simulation computed tomography (CT) scan was acquired for all patients. The dose-volume histograms of the phantom plan were compared with the initial plan. Significant reduction of the transverse diameter of the nasopharyngeal, the neck, and 2 parotid glands volume was observed on second CT compared with the first CT (mean reduction 7.48 {+-} 4.45 mm, 6.80 {+-} 15.14 mm, 5.70 {+-} 6.26 mL, and 5.04 {+-} 5.85 mL, respectively; p < 0.01). The maximum dose and V-40 of the spinal cord, mean dose, and V30 of the left and right parotid, and V-50 of the brain stem were increased significantly in the phantom plan compared with the initial plan (mean increase 4.75 {+-} 5.55 Gy, 7.18 {+-} 10.07%, 4.51 {+-} 8.55 Gy, 6.59 {+-} 17.82%, 5.33 {+-} 8.55 Gy, 11.68 {+-} 17.11% and 1.48 {+-} 3.67%, respectively; p < 0.01). On the basis of dose constraint criterion in the RTOG0225 protocol, the dose of the normal critical structures for 52.83% (28/53) of the phantom plans were out of limit compared with 1.89% (1/53) of the initial plans (p < 0.0001). Because of the significant change in anatomy and dose before the 25th fraction during IMRT, replanning should be necessary during IMRT with NPC.
Aurand, Alexander M; Dufour, Jonathan S; Marras, William S
2017-06-14
Optical motion capture is commonly used in biomechanics to measure human kinematics. However, no studies have yet examined the accuracy of optical motion capture in a large capture volume (>100m 3 ), or how accuracy varies from the center to the extreme edges of the capture volume. This study measured the dynamic 3D errors of an optical motion capture system composed of 42 OptiTrack Prime 41 cameras (capture volume of 135m 3 ) by comparing the motion of a single marker to the motion reported by a ThorLabs linear motion stage. After spline interpolating the data, it was found that 97% of the capture area had error below 200μm. When the same analysis was performed using only half (21) of the cameras, 91% of the capture area was below 200μm of error. The only locations that exceeded this threshold were at the extreme edges of the capture area, and no location had a mean error exceeding 1mm. When measuring human kinematics with skin-mounted markers, uncertainty of marker placement relative to underlying skeletal features and soft tissue artifact produce errors that are orders of magnitude larger than the errors attributed to the camera system itself. Therefore, the accuracy of this OptiTrack optical motion capture system was found to be more than sufficient for measuring full-body human kinematics with skin-mounted markers in a large capture volume (>100m 3 ). Copyright © 2017 Elsevier Ltd. All rights reserved.
DEFF Research Database (Denmark)
Mogensen, O.; Sørensen, Flemming Brandt; Bichel, P.
1999-01-01
We evaluated the following nine parameters with respect to their prognostic value in females with endometrial cancer: four stereologic parameters [mean nuclear volume (MNV), nuclear volume fraction, nuclear index and mitotic index], the immunohistochemical expression of cancer antigen (CA125...
Directory of Open Access Journals (Sweden)
Arti Parekh, MD
2018-01-01
Conclusions: We identified multiple risk factors for acute skin toxicity, including the use of PMRT and conventionally fractionated regimens. Elevated BMI, regional nodal irradiation, and chemotherapy use were associated with an increased risk of MD. Our findings highlight the need to explore the use of less toxic hypofractionated regimens in patients who are at the highest risk of acute skin toxicity, including those with a higher BMI and those receiving PMRT.
Franzin, Alberto; Panni, Pietro; Spatola, Giorgio; Vecchio, Antonella Del; Gallotti, Alberto L; Gigliotti, Carmen R; Cavalli, Andrea; Donofrio, Carmine A; Mortini, Pietro
2016-12-01
OBJECTIVE There are few reported series regarding volume-staged Gamma Knife radiosurgery (GKRS) for the treatment of large, complex, cerebral arteriovenous malformations (AVMs). The object of this study was to report the results of using volume-staged Gamma Knife radiosurgery for patients affected by large and complex AVMs. METHODS Data from 20 patients with large AVMs were prospectively included in the authors' AVM database between 2004 and 2012. A staging strategy was used when treating lesion volumes larger than 10 cm(3). Hemorrhage and seizures were the presenting clinical feature for 6 (30%) and 8 (40%) patients, respectively. The median AVM volume was 15.9 cm(3) (range 10.1-34.3 cm(3)). The mean interval between stages (± standard deviation) was 15 months (± 9 months). The median margin dose for each stage was 20 Gy (range 18-25 Gy). RESULTS Obliteration was confirmed in 8 (42%) patients after a mean follow-up of 45 months (range 19-87 months). A significant reduction (> 75%) of the original nidal volume was achieved in 4 (20%) patients. Engel Class I-II seizure status was reported by 75% of patients presenting with seizures (50% Engel Class I and 25% Engel Class II) after radiosurgery. After radiosurgery, 71.5% (5/7) of patients who had presented with a worsening neurological deficit reported a complete resolution or amelioration. None of the patients who presented acutely because of hemorrhage experienced a new bleeding episode during follow-up. One (5%) patient developed radionecrosis that caused sensorimotor hemisyndrome. Two (10%) patients sustained a bleeding episode after GKRS, although only 1 (5%) was symptomatic. High nidal flow rate and a time interval between stages of less than 11.7 months were factors significantly associated with AVM obliteration (p = 0.021 and p = 0.041, respectively). Patient age younger than 44 years was significantly associated with a greater than 75% reduction in AVM volume but not with AVM obliteration (p = 0
Mas-Ribas, Lluís; Hennawi, Joseph F.; Dijkstra, Mark; Davies, Frederick B.; Stern, Jonathan; Rix, Hans-Walter
2017-09-01
We present a new method to quantify the value of the escape fraction of ionizing photons, and the existence of ultra-faint galaxies clustered around brighter objects during the epoch of cosmic reionization, using the diffuse Lyα, continuum, and Hα emission observed around galaxies at z˜ 6. We model the surface brightness profiles of the diffuse halos, considering the fluorescent emission powered by ionizing photons escaping from the central galaxies, and the nebular emission from satellite star-forming sources, by extending the formalisms developed in Mas-Ribas & Dijkstra and Mas-Ribas et al. The comparison between our predicted profiles and Lyα observations at z = 5.7 and z = 6.6 favors a low ionizing escape fraction, {f}{esc}{ion}˜ 5 % , for galaxies in the range -19≳ {M}{UV}≳ -21.5. However, uncertainties and possible systematics in the observations do not allow for firm conclusions. We predict Hα and rest-frame visible continuum observations with the James Webb Space Telescope (JWST), and show that it will be able to detect extended (a few tens of kiloparsecs) fluorescent Hα emission powered by ionizing photons escaping from a bright, L≳ 5{L}* , galaxy. Such observations could differentiate fluorescent emission from nebular emission by satellite sources. We discuss how observations and stacking several objects may provide unique constraints on the escape fraction for faint galaxies and/or the abundance of ultra-faint radiation sources.
Chaos in discrete fractional difference equations
Indian Academy of Sciences (India)
2016-09-07
Sep 7, 2016 ... Abstract. Recently, the discrete fractional calculus (DFC) is receiving attention due to its potential applica- tions in the mathematical modelling of real-world phenomena with memory effects. In the present paper, the chaotic behaviour of fractional difference equations for the tent map, Gauss map and 2x(mod ...
Gérard, M; Jumeau, R; Pichon, B; Biau, J; Blais, E; Horion, J; Noël, G
2017-10-01
Cerebral radiation-induced toxicities after radiotherapy (RT) of brain tumors are frequent. The protection of organs at risk (OAR) is crucial, especially for brain tumors, to preserve cognition in cancer survivors. Dose constraints of cerebral OAR used in conventional RT, radiosurgery (SRS) and stereotactic radiotherapy (SRT) are debated. In fact, they are based on historical cohorts or calculated with old mathematical models. Values of α/β ratio of cerebral OAR are also controversial leading to misestimate the equivalent dose in 2Gy fractions or the biological equivalent dose, especially during hypofractionated RT. Although recent progresses in medical imaging, the diagnosis of radionecrosis remains difficult. In this article, we propose a large review of dose constraints used for three major cerebral OAR: the brain stem, the hippocampus and the brain. Copyright © 2017 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.
Directory of Open Access Journals (Sweden)
Christian Hüttich
2014-07-01
Full Text Available Growing stock volume is an important biophysical parameter describing the state and dynamics of the Boreal zone. Validation of growing stock volume (GSV maps based on satellite remote sensing is challenging due to the lack of consistent ground reference data. The monitoring and assessment of the remote Russian forest resources of Siberia can only be done by integrating remote sensing techniques and interdisciplinary collaboration. In this paper, we assess the information content of GSV estimates in Central Siberian forests obtained at 25 m from ALOS-PALSAR and 1 km from ENVISAT-ASAR backscatter data. The estimates have been cross-compared with respect to forest inventory data showing 34% relative RMSE for the ASAR-based GSV retrievals and 39.4% for the PALSAR-based estimates of GSV. Fragmentation analyses using a MODIS-based land cover dataset revealed an increase of retrieval error with increasing fragmentation of the landscape. Cross-comparisons of multiple SAR-based GSV estimates helped to detect inconsistencies in the forest inventory data and can support an update of outdated forest inventory stands.
Mapping high-fidelity volume rendering for medical imaging to CPU, GPU and many-core architectures.
Smelyanskiy, Mikhail; Holmes, David; Chhugani, Jatin; Larson, Alan; Carmean, Douglas M; Hanson, Dennis; Dubey, Pradeep; Augustine, Kurt; Kim, Daehyun; Kyker, Alan; Lee, Victor W; Nguyen, Anthony D; Seiler, Larry; Robb, Richard
2009-01-01
Medical volumetric imaging requires high fidelity, high performance rendering algorithms. We motivate and analyze new volumetric rendering algorithms that are suited to modern parallel processing architectures. First, we describe the three major categories of volume rendering algorithms and confirm through an imaging scientist-guided evaluation that ray-casting is the most acceptable. We describe a thread- and data-parallel implementation of ray-casting that makes it amenable to key architectural trends of three modern commodity parallel architectures: multi-core, GPU, and an upcoming many-core Intel architecture code-named Larrabee. We achieve more than an order of magnitude performance improvement on a number of large 3D medical datasets. We further describe a data compression scheme that significantly reduces data-transfer overhead. This allows our approach to scale well to large numbers of Larrabee cores.
Energy Technology Data Exchange (ETDEWEB)
Airimioaei, M., E-mail: mirela.airimioaei@yahoo.com [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” University of Iasi, Blv. Carol I, nr.11, 700506, Iasi (Romania); Stanculescu, R.; Preutu, V.; Ciomaga, C.; Horchidan, N. [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” University of Iasi, Blv. Carol I, nr.11, 700506, Iasi (Romania); Tascu, S. [Interdisciplinary Research Department – Field Science (RAMTECH), “Al. I. Cuza” University of Iasi, Blv. Carol I, nr.11, 700506, Iasi (Romania); Lutic, D.; Pui, A. [Faculty of Chemistry, “Al. I. Cuza” University of Iasi, 700506, Iasi (Romania); Mitoseriu, L., E-mail: lmtsr@uaic.ro [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” University of Iasi, Blv. Carol I, nr.11, 700506, Iasi (Romania)
2016-10-01
A systematic study concerning the effect of particle size and volume fraction of BaTiO{sub 3} filler on the functional properties of composite materials with poly-(ε-caprolactone) polymer matrix obtained by solvent casting method was performed. Two series of xBT-(1-x)PCL composites prepared by using BaTiO{sub 3} powders with two different particles size (60 nm and 400 nm) in different amounts (x = 2; 5; 10 and 20 vol %) were investigated. The X-ray diffraction analysis indicated a particle size dependence of phase symmetry for BT filler powders (cubic phase for ultrafine particles and tetragonal phase for larger particles size) and the formation of pure composites consisting of orthorhombic PCL and cubic or tetragonal BT with no chemical reactions between them. The micrographs of the composites revealed the formation of homogeneous composites with two distinct phases, a good dispersion of ferroelectric phase into the polymer matrix and a low content of air pores. Dielectric investigations at room temperature showed the increases of permittivity with increasing the particle volume fraction of ferroelectric filler as result of the “sum property” of the effective permittivity in composites. For a given concentration, the permittivity of composites increases with particle size, as result of a size effect of BT powder. The composites with low BT addition presents stable dielectric properties at bending cycles. The polarization-field dependences also show a BT-induced size dependence, i.e. at a given value of field, polarization is higher for the composites with coarser BT particles. The composition x = 0.05 with coarse particles can be considered as an optimum among these series for the stored energy density. - Highlights: • Study of particles size effect of BT on the properties of composites with PCL matrix. • xBT-(1-x)PCL composite films were prepared by solvent casting method. • Homogeneous composites with good dispersion of BT filler PCL matrix were
Fukuda, Nobuaki; Itatani, Keiichi; Kimura, Koichi; Ebihara, Aya; Negishi, Kazuaki; Uno, Kansei; Miyaji, Kagami; Kurabayashi, Masahiko; Takenaka, Katsu
2014-07-01
Vortex formation in the left ventricle (LV) can be visualized by novel vector flow mapping (VFM) based on color Doppler and speckle tracking data. The aim of this study was to evaluate the impact of a vortex during the ejection period using VFM. Color Doppler images were obtained to produce VFM images in 80 subjects (20 normal, 29 with dilated cardiomyopathy, and 31 with old myocardial infarction). The duration of the LV vortex was measured and expressed as the ratio to the ejection time (VTRe). The VTRe showed significant correlations with EDV (ρ = 0.672, p vortex existed for only a limited time during the early ejection period. In contrast, the lower the EF was, the longer the vortex remained during systole. Evaluation of vortices by VFM may noninvasively provide novel insights into the pathophysiology of impaired cardiac function.
Wang, B.
2017-10-15
Cellular microstructures within natural materials enlighten and promote the development of novel materials and structures in the industrial and engineering fields. Characterization of the microstructures and mechanical properties of these natural materials can help to understand the morphology-related mechanical properties and guide the structural optimization in industrial design. Among these natural cellular materials, pomelo peels, having a foam-like hierarchical microstructure, represent an ideal model for developing materials with high energy absorption efficiency. In this work, by combining X-ray tomographic imaging technique and digital volume correlation (DVC), in-situ stepwise uniaxial compression tests were performed to quantify the internal morphological evolution and kinematic responses of pomelo peel samples during compression. Via these experiments, the varying microstructure features and thus diverse resistance to compression from endocarp to exocarp are examined, and the evolution of both bundles bending and large strain domain from endocarp to mesocarp are explored. Based on the experimental results, the microstructure-related mechanical properties of pomelo peels in response to compressive loading that demonstrates nearly linear morphology-mechanics relationship were revealed.
Identification of myocardial diffuse fibrosis by 11 heartbeat MOLLI T 1 mapping
DEFF Research Database (Denmark)
Vassiliou, Vassilios S; Wassilew, Katharina; Cameron, Donnie
2017-01-01
OBJECTIVES: Our objectives involved identifying whether repeated averaging in basal and mid left ventricular myocardial levels improves precision and correlation with collagen volume fraction for 11 heartbeat MOLLI T 1 mapping versus assessment at a single ventricular level. MATERIALS AND METHODS...
Energy Technology Data Exchange (ETDEWEB)
Vieira, Marcelo L.C.; Nomura, Cesar H.; Tranchesi Junior, Bernardino; Oliveira, Wercules A. de; Naccarato, Gustavo; Serpa, Bruna S.; Cury, Alexandre; Passos, Rodrigo B.D.; Nobrega, Marcel V. da; Funari, Marcelo B.G.; Pfefermam, Abhaham; Makdisse, Marcia; Fischer, Claudio H.; Morhy, Samira S., E-mail: luiz766@terra.com.br [Hospital Israelita Albert Einstein, Sao Paulo, SP (Brazil)
2008-10-15
Background and objective: Few studies addressed the comparison between real-time 3D echocardiography (RT3DE) and cardiac computed tomography (CCT) concerning left ventricular ejection fraction and volumes assessment. We sought to compare both techniques regarding left ventricle (LV) ejection fraction function and volumes analysis. Methods: we studied by RT3DE (Philips IE 33, And, MA, USA) and by CCT (Toshiba, 64-slice, Otawara, Japan) 41 consecutive patients (29 males, 58 ± 11 yrs). We analysed by both techniques LVEF, LVEDV, LVESV. RT3DE and CCT data were compared by coefficients of determination (r: Pearson), Bland and Altman test and linear regression, 95% CI. Results: RT3DE data: LVEF ranged from 56.7 to 78.9 % (65.3 + 5.7 ); LVEDV ranged from 49.6 to 178.2 (88 + 27.5) mL; LVESV from 11.4 to 78 ( 33.9 + 13.7) mL. CCT data: LVEF ranged from 53 to 86 % (67.3 + 7.9 ); LVEDV ranged from 51 to 186 (106.4 + 30.7) mL; LVESV from 7 to 72 ( 35.1 + 13.8) mL. Correlations relative to RT3DE and CCT were: LVEF (r: 0. 7877, p<0.0001, 95 % CI 0.6327 to 0.8853 ); LVEDV (r:0.7671, p<0.0001, 95 % CI 0.5974 to 0.8745); LVESV (r: 0.8121, p<0.0001, 95 % CI 0.6659 to 0.8957). Conclusions: it was observed adequate correlation between real-time 3D echocardiography and cardiac computed tomography concerning ejection fraction and volumes assessment. (author)
Online maps with APIs and webservices
Peterson, Michael P
2014-01-01
With the Internet now the primary method of accessing maps, this volume examines developments in the world of online map delivery, focusing in particular on application programmer interfaces such as the Google Maps API, and their utility in thematic mapping.
Iriki, Yasuhisa; Ishida, Sanemasa; Oketani, Naoya; Ichiki, Hitoshi; Okui, Hideki; Ninomiya, Yuichi; Maenosono, Ryuichi; Matsushita, Takehiko; Miyata, Masaaki; Hamasaki, Shuichi; Tei, Chuwa
2011-11-01
Controversy exists as to whether atrial fibrillation (AF) ablation guided solely by complex fractionated atrial electrogram (CFAE) has a good outcome despite not requiring pulmonary vein isolation (PVI). The purpose of this study was to evaluate the effectiveness of AF ablation guided solely by targeting CFAE areas, and to determine whether its clinical efficacy has any relationship with unintentionally isolating the PV. We studied 100 consecutive patients (ages 59 ± 11 years; 54 with paroxysmal, 35 persistent, and 11 long-standing persistent AF), who underwent CFAE-ablation. PV potential (PVP) was recorded before and after ablation. After excluding 39 patients in whom sinus rhythm could not be maintained before ablation by internal cardioversion and/or who had a history of PVI(s), PVPs were analyzed. AF was terminated during ablation in 98% of paroxysmal, 80% of persistent, and 55% of long-standing persistent AF patients. Nifekalant (0.3-0.6 mg/kg) was administered in 30%, 57%, and 83%, respectively. The common areas of CFAE around the PVs were anterior to the right PVs, posterior to the left PVs, and at the ridge of the left atrial appendage. Among 215 PVs in 61 patients (42 paroxysmal, 19 persistent), only 17 PVs (8%) were unintentionally isolated. The atrial potential to PVP was prolonged (>30 ms) in 13% of PVs. After at least 12 months of follow-up (23 ± 5 months), 65% of paroxysmal (11% with drug), 54% of persistent (37% with drug), and 45% of long-standing (60% with drug) AF patients were free from atrial arrhythmia after one session. CFAE-ablation terminates AF without isolating PVs in a high percentage of patients, and yields excellent clinical outcomes. Copyright Â© 2011 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.
Bhattacharyya, Sonalee; Namakshi, Nama; Zunker, Christina; Warshauer, Hiroko K.; Warshauer, Max
2016-01-01
Making math more engaging for students is a challenge that every teacher faces on a daily basis. These authors write that they are constantly searching for rich problem-solving tasks that cover the necessary content, develop critical-thinking skills, and engage student interest. The Mystery Fraction activity provided here focuses on a key number…
Fuxe, Kjell; Dahlström, Annica; Höistad, Malin; Marcellino, Daniel; Jansson, Anders; Rivera, Alicia; Diaz-Cabiale, Zaida; Jacobsen, Kirsten; Tinner-Staines, Barbro; Hagman, Beth; Leo, Giuseppina; Staines, William; Guidolin, Diego; Kehr, Jan; Genedani, Susanna; Belluardo, Natale; Agnati, Luigi F
2007-08-01
After Golgi-Cajal mapped neural circuits, the discovery and mapping of the central monoamine neurons opened up for a new understanding of interneuronal communication by indicating that another form of communication exists. For instance, it was found that dopamine may be released as a prolactin inhibitory factor from the median eminence, indicating an alternative mode of dopamine communication in the brain. Subsequently, the analysis of the locus coeruleus noradrenaline neurons demonstrated a novel type of lower brainstem neuron that monosynaptically and globally innervated the entire CNS. Furthermore, the ascending raphe serotonin neuron systems were found to globally innervate the forebrain with few synapses, and where deficits in serotonergic function appeared to play a major role in depression. We propose that serotonin reuptake inhibitors may produce antidepressant effects through increasing serotonergic neurotrophism in serotonin nerve cells and their targets by transactivation of receptor tyrosine kinases (RTK), involving direct or indirect receptor/RTK interactions. Early chemical neuroanatomical work on the monoamine neurons, involving primitive nervous systems and analysis of peptide neurons, indicated the existence of alternative modes of communication apart from synaptic transmission. In 1986, Agnati and Fuxe introduced the theory of two main types of intercellular communication in the brain: wiring and volume transmission (WT and VT). Synchronization of phasic activity in the monoamine cell clusters through electrotonic coupling and synaptic transmission (WT) enables optimal VT of monoamines in the target regions. Experimental work suggests an integration of WT and VT signals via receptor-receptor interactions, and a new theory of receptor-connexin interactions in electrical and mixed synapses is introduced. Consequently, a new model of brain function must be built, in which communication includes both WT and VT and receptor-receptor interactions in the
Chang, Gregory; Wiggins, Graham C.; Xia, Ding; Lattanzi, Riccardo; Madelin, Guillaume; Raya, Jose G.; Finnerty, Matthew; Fujita, Hiroyuki; Recht, Michael P.; Regatte, Ravinder R.
2011-01-01
Purpose To compare a new birdcage-transmit, 28 channel-receive array (28 Ch) coil and a quadrature volume coil for 7 Tesla morphologic MRI and T2 mapping of knee cartilage. Methods The right knees of ten healthy subjects were imaged on a 7 Tesla whole body MR scanner using both coils. 3-dimensional fast low-angle shot (3D-FLASH) and multi-echo spin-echo (MESE) sequences were implemented. Cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), thickness, and T2 values were assessed. Results SNR/CNR was 17–400% greater for the 28 Ch compared to the quadrature coil (p≤0.005). Bland-Altman plots show mean differences between measurements of tibial/femoral cartilage thickness and T2 values obtained with each coil to be small (−0.002±0.009 cm/0.003±0.011 cm) and large (−6.8±6.7 ms/−8.2±9.7 ms), respectively. For the 28 Ch coil, when parallel imaging with acceleration factors (AF) 2, 3, and 4 was performed, SNR retained was: 62–69%, 51–55%, and 39–45%. Conclusion A 28 Ch knee coil provides increased SNR/CNR for 7T cartilage morphologic imaging and T2 mapping. Coils should be switched with caution during clinical studies because T2 values may differ. The greater SNR of the 28 Ch coil could be used to perform parallel imaging with AF2 and obtain similar SNR as the quadrature coil. PMID:22095723
Jerome, N P; d'Arcy, J A; Feiweier, T; Koh, D-M; Leach, M O; Collins, D J; Orton, M R
2016-12-21
The bi-exponential intravoxel-incoherent-motion (IVIM) model for diffusion-weighted MRI (DWI) fails to account for differential T 2 s in the model compartments, resulting in overestimation of pseudodiffusion fraction f. An extended model, T2-IVIM, allows removal of the confounding echo-time (TE) dependence of f, and provides direct compartment T 2 estimates. Two consented healthy volunteer cohorts (n = 5, 6) underwent DWI comprising multiple TE/b-value combinations (Protocol 1: TE = 62-102 ms, b = 0-250 mm-2s, 30 combinations. Protocol 2: 8 b-values 0-800 mm-2s at TE = 62 ms, with 3 additional b-values 0-50 mm-2s at TE = 80, 100 ms; scanned twice). Data from liver ROIs were fitted with IVIM at individual TEs, and with the T2-IVIM model using all data. Repeat-measures coefficients of variation were assessed for Protocol 2. Conventional IVIM modelling at individual TEs (Protocol 1) demonstrated apparent f increasing with longer TE: 22.4 ± 7% (TE = 62 ms) to 30.7 ± 11% (TE = 102 ms); T2-IVIM model fitting accounted for all data variation. Fitting of Protocol 2 data using T2-IVIM yielded reduced f estimates (IVIM: 27.9 ± 6%, T2-IVIM: 18.3 ± 7%), as well as T 2 = 42.1 ± 7 ms, 77.6 ± 30 ms for true and pseudodiffusion compartments, respectively. A reduced Protocol 2 dataset yielded comparable results in a clinical time frame (11 min). The confounding dependence of IVIM f on TE can be accounted for using additional b/TE images and the extended T2-IVIM model.
Directory of Open Access Journals (Sweden)
Kalle Eerikäinen
2012-12-01
Full Text Available An approach based on the nearest neighbors techniques is presented for producing thematic maps of forest cover (forest/non-forest and total stand volume for the Terai region in southern Nepal. To create the forest cover map, we used a combination of Landsat TM satellite data and visual interpretation data, i.e., a sample grid of visual interpretation plots for which we obtained the land use classification according to the FAO standard. These visual interpretation plots together with the field plots for volume mapping originate from an operative forest inventory project, i.e., the Forest Resource Assessment of Nepal (FRA Nepal project. The field plots were also used in checking the classification accuracy. MODIS satellite data were used as a reference in a local correction approach conducted for the relative calibration of Landsat TM images. This study applied a non-parametric k-nearest neighbor technique (k-NN to the forest cover and volume mapping. A tree height prediction approach based on a nonlinear, mixed-effects (NLME modeling procedure is presented in the Appendix. The MODIS image data performed well as reference data for the calibration approach applied to make the Landsat image mosaic. The agreement between the forest cover map and the field observed values of forest cover was substantial in Western Terai (KHAT 0.745 and strong in Eastern Terai (KHAT 0.825. The forest cover and volume maps that were estimated using the k-NN method and the inventory data from the FRA Nepal project are already appropriate and valuable data for research purposes and for the planning of forthcoming forest inventories. Adaptation of the methods and techniques was carried out using Open Source software tools.
Fraction Reduction through Continued Fractions
Carley, Holly
2011-01-01
This article presents a method of reducing fractions without factoring. The ideas presented may be useful as a project for motivated students in an undergraduate number theory course. The discussion is related to the Euclidean Algorithm and its variations may lead to projects or early examples involving efficiency of an algorithm.
Nadjiri, Jonathan; Nieberler, Hanna; Hendrich, Eva; Will, Albrecht; Pellegrini, Costanza; Husser, Oliver; Hengstenberg, Christian; Greiser, Andreas; Martinoff, Stefan; Hadamitzky, Martin
2016-11-01
The benefit of a transcatheter aortic valve replacement (TAVR) can differ in patients, and therapy bears severe risks. High-degree aortic stenosis can lead to cardiac damage such as diffuse myocardial fibrosis, evaluable by extra-cellular volume (ECV) in CMR. Therefore, fibrosis might be a possible risk factor for unfavorable outcome after TAVR. We sought to assess the prognostic value of T1-mapping and ECV to predict adverse events during and after TAVR. The study population consisted of patients undergoing clinically indicated TAVR by performing additional CMR with native and contrast-enhanced T1-mapping sequences for additional evaluation of ECV. Study endpoints were congestive heart failure (CHF) and TAVR-associated conduction abnormalities defined as new onset of left bundle branch block (LBBB), AV-Block or implantation of a pacemaker. 94 patients were examined and followed. Median follow up time was 187 days (IQR 79-357 days). ECV was increased (>30 %) in 38 patients (40 %). There was no significant correlation between ECV and death, Hazard ratio (HR) 0.847 (95 % CI 0.335; 2.14), p = 0.72. ECV in patients with subsequent CHF was higher than in those without an event (33.5 ± 4.6 and 29.1 ± 4.1 %, respectively), but the difference just did not reach the level of significance HR 2.16 (95 % CI 0.969; 4.84), p = 0.06. Patients with post-TAVR conduction abnormality (LBBB, AV-block or pacemaker implantation) had statistically relevant lower ECV values compared to those without an event. Patients with an event had a mean ECV of 28.1 ± 3.16 %; patients without an event had a mean ECV of 29.8 ± 4.53, HR 0.56 (95 % CI 0.32; 0.96), p = 0.036. In this study, elevated myocardial ECV is a predictor of CHF by trend; CMR may be helpful in identifying patients with a high risk for post-TAVR cardiac decompensation benefitting from an intensified post-interventional surveillance. Patients with post-TAVR conductions abnormalities
Energy Technology Data Exchange (ETDEWEB)
Tinnel, E.P.; Hinze, W.J.
1981-09-01
Total intensity magnetic anomaly data acquired as a supplement to radiometric data in the DOE National Uranium Resource Evaluation (NURE) Program are useful in preparing regional profile and contour maps. Survey-contractor-supplied magnetic anomaly data are subjected to a multiprocess, computer-based procedure which prepares these data for presentation. This procedure is used to produce the following machine plotted maps of National Topographic Map Series quadrangle units at a 1:250,000 scale: (1) profile map of contractor-supplied magnetic anomaly data, (2) profile map of high-cut filtered data with contour levels of each profile marked and annotated on the associated flight track, (3) profile map of critical-point data with contour levels indicated, and (4) contour map of filtered and selected data. These quadrangle maps are supplemented with a range of statistical measures of the data which are useful in quality evaluation.
Transportable Maps Software. Volume I.
1982-07-01
FACj DIMENSION hAMES(6,3) BYTE NAMES DATA lITVP/Ihi,1HN.IHA,114GIHE,0/ !Default DATA I2TYP/ IHD ,lHM,lHA11b4P.1hS,0/ ! Default DATA Ac/ILo./ £Default DATA...NAMEs/1HI,lHM,INA. 1HG,IIE,0. IHD ,INN,1NA.HP1I4S,O. * INA,114D,1HAIHP,114T.0/ 12x2 TYPE 500r 500 FORtNAT(/,lX,32(1H*) ./,IX, S ,30X, *-,/,IX...3331,3 DOn 0 110 JjPin1,16 NL48KL4+1 ITS8ISVM9(JJWIU.4,IT) JT53335 %blIIS4PT(ITS#JT5) .AND*0 JTSB16-JJP NOXNW.Og.ll&HFTCITSJTS) 110 CONTINUE L4T(JJJ
Fractional Derivative as Fractional Power of Derivative
Tarasov, Vasily E.
2007-01-01
Definitions of fractional derivatives as fractional powers of derivative operators are suggested. The Taylor series and Fourier series are used to define fractional power of self-adjoint derivative operator. The Fourier integrals and Weyl quantization procedure are applied to derive the definition of fractional derivative operator. Fractional generalization of concept of stability is considered.
Directory of Open Access Journals (Sweden)
Stepan Havranek
Full Text Available Left atrial (LA enlargement is a predictor of worse outcome after catheter ablation for atrial fibrillation (AF. Widely used two-dimensional (2D-echocardiography is inaccurate and underestimates real LA volume (LAV. We hypothesized that baseline clinical characteristics of patients can be used to adjust 2D-ECHO indices of LAV in order to minimize this disagreement.The study enrolled 535 patients (59 ± 9 years; 67% males; 43% paroxysmal AF who underwent catheter ablation for AF in three specialized centers. We investigated multivariately the relationship between 2D-echocardiographic indices of LA size, specifically LA diameter in M-mode in the parasternal long-axis view (LAD, LAV assessed by the prolate-ellipsoid method (LAVEllipsoid, LAV by the planimetric method (LAVPlanimetry, and LAV derived from 3D-electroanatomic mapping (LAVCARTO.Cubed LAD of 106 ± 45 ml, LAVEllipsoid of 72 ± 24 ml and LAVPlanimetry of 88 ± 30 ml correlated only modestly (r = 0.60, 0.69, and 0.53, respectively with LAVCARTO of 137 ± 46 ml, which was significantly underestimated with a bias (±1.96 standard deviation of -31 (-111; +49 ml, -64 (-132; +2 ml, and -49 (-125; +27 ml, respectively; p < 0.0001 for their mutual difference. LA enlargement itself, age, gender, type of AF, and the presence of structural heart disease were independent confounders of measurement error of 2D-echocardiographic LAV.Accuracy and precision of all 2D-echocardiographic LAV indices are poor. Their agreement with true LAV can be significantly improved by multivariate adjustment to clinical characteristics of patients.
Stefanescu, Doru M.; Moitra, Avijit; Kacar, A. Sedat; Dhindaw, Brij K.
1990-01-01
Directional solidification experiments in a Bridgman-type furnace were used to study particle behavior at the liquid/solid interface in aluminum metal matrix composites. Graphite or silicon-carbide particles were first dispersed in aluminum-base alloys via a mechanically stirred vortex. Then, 100-mm-diameter and 120-mm-long samples were cast in steel dies and used for directional solidification. The processing variables controlled were the direction and velocity of solidification and the temperature gradient at the interface. The material variables monitored were the interface energy, the liquid/particle density difference, the particle/liquid thermal conductivity ratio, and the volume fraction of particles. These properties were changed by selecting combinations of particles (graphite or silicon carbide) and alloys (Al-Cu, Al-Mg, Al-Ni). A model which consideres process thermodynamics, process kinetics (including the role of buoyant forces), and thermophysical properties was developed. Based on solidification direction and velocity, and on materials properties, four types of behavior were predicted. Sessile drop experiments were also used to determine some of the interface energies required in calculation with the proposed model. Experimental results compared favorably with model predictions.
Energy Technology Data Exchange (ETDEWEB)
Wang, Bo, E-mail: xiaoboking@gmail.com [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xianning West Road No. 28, Xi' an 710049, Shaanxi Province (China); State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi' an Jiaotong University, Xianning West Road No. 28, Xi' an 710049, Shaanxi Province (China); Qin, Yi [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xianning West Road No. 28, Xi' an 710049, Shaanxi Province (China); Jin, Feng [State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi' an Jiaotong University, Xianning West Road No. 28, Xi' an 710049, Shaanxi Province (China); Yang, Jian-Feng, E-mail: yang155@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xianning West Road No. 28, Xi' an 710049, Shaanxi Province (China); Ishizaki, Kozo [Department of Mechanical Engineering, Nagaoka University of Technology, Nagaoka 940-2188 (Japan)
2014-06-01
Cubic boron nitride/tungsten carbide–cobalt (cBN/WC–Co) composites were fabricated by pulse electric current sintering (PECS), using Ni–P as sintering additives to promote low temperature densification. The effect of cBN particle size and volume fraction on the densification, microstructure and mechanical properties of WC–Co composites was investigated. There was no phase transformation from cBN to hBN (hexagonal BN) with low-hardness due to low sintering temperature (1100–1200 °C) and short sintering time. Smaller cBN particle led to lower sinter-ability of the composites due to its high specific surface area. The 30 vol% 10–14 µm cBN/WC–Co composite (P14V30) exhibited high hardness (18.3 GPa, 1200 °C) and high fracture toughness (15.6 MP·m{sup 1/2}, 1000 °C). The high hardness resulted from the homogeneously dispersed cBN particles, which had a good bonding with the WC matrix. Increased fracture toughness was mainly attributed to crack deflection or bridging and pullout of cBN grains.
Directory of Open Access Journals (Sweden)
Chan-Gi Park
2016-01-01
Full Text Available Hybrid glass/jute fiber reinforced polymer (HGJFRP composite bars were manufactured for concrete structures, and their interlaminar shear stress and tensile performance were evaluated. HGJFRP composite bars were manufactured using a combination of pultrusion and braiding processes. Jute fiber was surface-treated with a silane coupling agent. The mixing ratio of the fiber to the vinyl ester used in the HGJFRP composite bars was 7 : 3. Jute fiber was used to replace glass fiber in proportions of 0, 30, 50, 70, and 100%. The interlaminar shear stress decreased as the proportion of jute fiber increased. Fractures appeared due to delamination between the surface-treated component and the main part of the HGJFRP composite bar. Tensile load-strain curves with 50% jute fiber exhibited linear behavior. With a jute fiber volume fraction of 70%, some plastic deformation occurred. A jute fiber mixing ratio of 100% resulted in a display of linear elastic brittle behavior from the fiber; however, when the surface of the fiber was coated with poly(vinyl acetate, following failure, the jute fiber exhibited partial load resistance. The tensile strength decreased as the jute fiber content increased; however, the tensile strength did not vary linearly with jute fiber content.
Fractional complex transform for fractional differential equations
National Research Council Canada - National Science Library
Lİ, Zheng Biao; HE, Ji Huan
2010-01-01
Fractional complex transform is proposed to convert fractional differential equations into ordinary differential equations, so that all analytical methods devoted to advanced calculus can be easily...
Quantitative metric theory of continued fractions
Indian Academy of Sciences (India)
Quantitative versions of the central results of the metric theory of contin- ued fractions were given primarily by C. ... Continued fractions; ergodic averages; metric theory of numbers. Mathematics Subject ... of subsets of X, a probability measure μ on the measurable space (X, β) and a measurable self-map T of X that is also ...
2014-01-01
Background Systemic sclerosis (SSc) is characterised by multi-organ tissue fibrosis including the myocardium. Diffuse myocardial fibrosis can be detected non-invasively by T1 and extracellular volume (ECV) quantification, while focal myocardial inflammation and fibrosis may be detected by T2-weighted and late gadolinium enhancement (LGE), respectively, using cardiovascular magnetic resonance (CMR). We hypothesised that multiparametric CMR can detect subclinical myocardial involvement in patients with SSc. Methods 19 SSc patients (18 female, mean age 55 ± 10 years) and 20 controls (19 female, mean age 56 ± 8 years) without overt cardiovascular disease underwent CMR at 1.5T, including cine, tagging, T1-mapping, T2-weighted, LGE imaging and ECV quantification. Results Focal fibrosis on LGE was found in 10 SSc patients (53%) but none of controls. SSc patients also had areas of myocardial oedema on T2-weighted imaging (median 13 vs. 0% in controls). SSc patients had significantly higher native myocardial T1 values (1007 ± 29 vs. 958 ± 20 ms, p 990 ms (median 52 vs. 3% in controls) and expansion of ECV (35.4 ± 4.8 vs. 27.6 ± 2.5%, p ECV were significantly elevated in SSc and correlated with disease activity and severity. Although biventricular size and global function were preserved, there was impairment in the peak systolic circumferential strain (-16.8 ± 1.6 vs. -18.6 ± 1.0, p < 0.001) and peak diastolic strain rate (83 ± 26 vs. 114 ± 16 s-1, p < 0.001) in SSc, which inversely correlated with diffuse myocardial fibrosis indices. Conclusions Cardiac involvement is common in SSc even in the absence of cardiac symptoms, and includes chronic myocardial inflammation as well as focal and diffuse myocardial fibrosis. Myocardial abnormalities detected on CMR were associated with impaired strain parameters, as well as disease activity and severity in SSc patients. CMR may be useful in future in the study of treatments aimed at preventing or reducing adverse myocardial
Fractional vector calculus for fractional advection dispersion
Meerschaert, Mark M.; Mortensen, Jeff; Wheatcraft, Stephen W.
2006-07-01
We develop the basic tools of fractional vector calculus including a fractional derivative version of the gradient, divergence, and curl, and a fractional divergence theorem and Stokes theorem. These basic tools are then applied to provide a physical explanation for the fractional advection-dispersion equation for flow in heterogeneous porous media.
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-09-01
This document contains the Large Maps for the F-Area and H-Area Seepage Basins Groundwater Monitoring Reports for the Savannah River Plant in Aiken, South Carolina. The maps contain the ground-water concentrations of various heavy metals and radionuclides in the vicinity of the seepage basins for the dates sampled.
2012-04-01
The Long-Term Plan for Concrete Pavement Research and Technology (CP Road Map) is a holistic strategic plan for concrete : pavement research and technology transfer. The CP Road Map is a living plan that includes 12 distinct but integrated research :...
2005-09-01
The Long-Term Plan for Concrete Pavement Research and Technology (CP Road Map) is a holistic, strategic plan : for concrete pavement research and technology transfer. The CP Road Map is a 7- to 10-year plan that includes 12 : distinct but integrated ...
2012-07-01
The Long-Term Plan for Concrete Pavement Research and Technology (CP Road Map) is a holistic strategic plan for : concrete pavement research and technology transfer. The CP Road Map is a living plan that includes 12 distinct but : integrated research...
Bergstra, Jan A.
2015-01-01
In the context of an involutive meadow a precise definition of fractions is formulated and on that basis formal definitions of various classes of fractions are given. The definitions follow the fractions as terms paradigm. That paradigm is compared with two competing paradigms for storytelling on fractions: fractions as values and fractions as pairs.
Alexander, R. H. (Principal Investigator); Fitzpatrick, K. A.
1975-01-01
The author has identified the following significant results. Level 2 land use maps produced at three scales (1:24,000, 1:100,000, and 1:250,000) from high altitude photography were compared with each other and with point data obtained in the field. The same procedures were employed to determine the accuracy of the Level 1 land use maps produced at 1:250,000 from high altitude photography and color composite ERTS imagery. Accuracy of the Level 2 maps was 84.9 percent at 1:24,000, 77.4 percent at 1:100,000 and 73.0 percent at 1:250,000. Accuracy of the Level 1 1:250,000 maps was 76.5 percent for aerial photographs and 69.5 percent for ERTS imagery. The cost of Level 2 land use mapping at 1:24,000 was found to be high ($11.93 per sq km). The cost of mapping at 1:100,000 ($1.75) was about two times as expensive as mapping at 1:250,000 ($.88), and the accuracy increased by only 4.4 percent.
Directory of Open Access Journals (Sweden)
Arheden Håkan
2011-04-01
Full Text Available Abstract Background Functional and morphological changes of the heart influence blood flow patterns. Therefore, flow patterns may carry diagnostic and prognostic information. Three-dimensional, time-resolved, three-directional phase contrast cardiovascular magnetic resonance (4D PC-CMR can image flow patterns with unique detail, and using new flow visualization methods may lead to new insights. The aim of this study is to present and validate a novel visualization method with a quantitative potential for blood flow from 4D PC-CMR, called Volume Tracking, and investigate if Volume Tracking complements particle tracing, the most common visualization method used today. Methods Eight healthy volunteers and one patient with a large apical left ventricular aneurysm underwent 4D PC-CMR flow imaging of the whole heart. Volume Tracking and particle tracing visualizations were compared visually side-by-side in a visualization software package. To validate Volume Tracking, the number of particle traces that agreed with the Volume Tracking visualizations was counted and expressed as a percentage of total released particles in mid-diastole and end-diastole respectively. Two independent observers described blood flow patterns in the left ventricle using Volume Tracking visualizations. Results Volume Tracking was feasible in all eight healthy volunteers and in the patient. Visually, Volume Tracking and particle tracing are complementary methods, showing different aspects of the flow. When validated against particle tracing, on average 90.5% and 87.8% of the particles agreed with the Volume Tracking surface in mid-diastole and end-diastole respectively. Inflow patterns in the left ventricle varied between the subjects, with excellent agreement between observers. The left ventricular inflow pattern in the patient differed from the healthy subjects. Conclusion Volume Tracking is a new visualization method for blood flow measured by 4D PC-CMR. Volume Tracking
Directory of Open Access Journals (Sweden)
Ferjan Ormeling
2008-09-01
Full Text Available Discussing the requirements for map data quality, map users and their library/archives environment, the paper focuses on the metadata the user would need for a correct and efficient interpretation of the map data. For such a correct interpretation, knowledge of the rules and guidelines according to which the topographers/cartographers work (such as the kind of data categories to be collected, and the degree to which these rules and guidelines were indeed followed are essential. This is not only valid for the old maps stored in our libraries and archives, but perhaps even more so for the new digital files as the format in which we now have to access our geospatial data. As this would be too much to ask from map librarians/curators, some sort of web 2.0 environment is sought where comments about data quality, completeness and up-to-dateness from knowledgeable map users regarding the specific maps or map series studied can be collected and tagged to scanned versions of these maps on the web. In order not to be subject to the same disadvantages as Wikipedia, where the ‘communis opinio’ rather than scholarship, seems to be decisive, some checking by map curators of this tagged map use information would still be needed. Cooperation between map curators and the International Cartographic Association ( ICA map and spatial data use commission to this end is suggested.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 10. Ramachandran and his Map. C Ramakrishnan. General Article Volume 6 Issue 10 October 2001 pp 48-56. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/006/10/0048-0056. Author Affiliations.
Alomari, Ali Hamed; Wille, Marie-Luise; Langton, Christian M
2018-02-01
Conventional mechanical testing is the 'gold standard' for assessing the stiffness (N mm -1 ) and strength (MPa) of bone, although it is not applicable in-vivo since it is inherently invasive and destructive. The mechanical integrity of a bone is determined by its quantity and quality; being related primarily to bone density and structure respectively. Several non-destructive, non-invasive, in-vivo techniques have been developed and clinically implemented to estimate bone density, both areal (dual-energy X-ray absorptiometry (DXA)) and volumetric (quantitative computed tomography (QCT)). Quantitative ultrasound (QUS) parameters of velocity and attenuation are dependent upon both bone quantity and bone quality, although it has not been possible to date to transpose one particular QUS parameter into separate estimates of quantity and quality. It has recently been shown that ultrasound transit time spectroscopy (UTTS) may provide an accurate estimate of bone density and hence quantity. We hypothesised that UTTS also has the potential to provide an estimate of bone structure and hence quality. In this in-vitro study, 16 human femoral bone samples were tested utilising three techniques; UTTS, micro computed tomography (μCT), and mechanical testing. UTTS was utilised to estimate bone volume fraction (BV/TV) and two novel structural parameters, inter-quartile range of the derived transit time (UTTS-IQR) and the transit time of maximum proportion of sonic-rays (TTMP). μCT was utilised to derive BV/TV along with several bone structure parameters. A destructive mechanical test was utilised to measure the stiffness and strength (failure load) of the bone samples. BV/TV was calculated from the derived transit time spectrum (TTS); the correlation coefficient (R 2 ) with μCT-BV/TV was 0.885. For predicting mechanical stiffness and strength, BV/TV derived by both μCT and UTTS provided the strongest correlation with mechanical stiffness (R 2 =0.567 and 0.618 respectively) and
Reply to "Comment on 'Fractional quantum mechanics' and 'Fractional Schrödinger equation' ".
Laskin, Nick
2016-06-01
The fractional uncertainty relation is a mathematical formulation of Heisenberg's uncertainty principle in the framework of fractional quantum mechanics. Two mistaken statements presented in the Comment have been revealed. The origin of each mistaken statement has been clarified and corrected statements have been made. A map between standard quantum mechanics and fractional quantum mechanics has been presented to emphasize the features of fractional quantum mechanics and to avoid misinterpretations of the fractional uncertainty relation. It has been shown that the fractional probability current equation is correct in the area of its applicability. Further studies have to be done to find meaningful quantum physics problems with involvement of the fractional probability current density vector and the extra term emerging in the framework of fractional quantum mechanics.
Abdelgawad, Enas A; Higazi, Mahmoud M; Abdelbaky, Abdelraouf O; Abdelghany, Hosny S
2017-02-01
Recent developments in treatment of ischemic stroke increased importance of defining limits of ischemic insult by imaging. Some studies postulated that CTP is a promising technique, which can discriminate between ischemic core and penumbra. In this study, we sought to evaluate diagnostic performance of CTP-CBV colour maps, regarded as a marker of acute infarct; in comparison with DWI. We retrospectively analyzed 48 patients with CTA proved major ischemic stroke within 12hours of onset, they had DWI and CTP exams within 1hour of each other, regardless of order. DWI sizes were calculated. Sensitivity, specificity, PPV and NPV of CBV colour maps for identification of acute infarcts were calculated. ROC curve was constructed. CBV colour maps missed a lot of small infarcts that were identified by DWI with an overall diagnostic accuracy of (62.5%) and low sensitivity (38.5%) for patients whom DWI sizecolour maps (P=0.005). Assuming direct equivalence of DWI and CBV-based core might be unrealistic for individual patients in clinical practice. CBV colour maps are highly specific for acute infarcts, but with lack of sufficient sensitivity; particularly for small sized infarcts. Copyright © 2016 Elsevier Masson SAS. All rights reserved.
Fractional boundary value problems with multiple orders of fractional derivatives and integrals
Directory of Open Access Journals (Sweden)
Sotiris K. Ntouyas
2017-04-01
Full Text Available In this article we study a new class of boundary value problems for fractional differential equations and inclusions with multiple orders of fractional derivatives and integrals, in both fractional differential equation and boundary conditions. The Sadovski's fixed point theorem is applied in the single-valued case while, in multi-valued case, the nonlinear alternative for contractive maps is used. Some illustrative examples are also included.
Directory of Open Access Journals (Sweden)
Alexandre ten Caten
2013-04-01
Full Text Available Digital information generates the possibility of a high degree of redundancy in the data available for fitting predictive models used for Digital Soil Mapping (DSM. Among these models, the Decision Tree (DT technique has been increasingly applied due to its capacity of dealing with large datasets. The purpose of this study was to evaluate the impact of the data volume used to generate the DT models on the quality of soil maps. An area of 889.33 km² was chosen in the Northern region of the State of Rio Grande do Sul. The soil-landscape relationship was obtained from reambulation of the studied area and the alignment of the units in the 1:50,000 scale topographic mapping. Six predictive covariates linked to the factors soil formation, relief and organisms, together with data sets of 1, 3, 5, 10, 15, 20 and 25 % of the total data volume, were used to generate the predictive DT models in the data mining program Waikato Environment for Knowledge Analysis (WEKA. In this study, sample densities below 5 % resulted in models with lower power of capturing the complexity of the spatial distribution of the soil in the study area. The relation between the data volume to be handled and the predictive capacity of the models was best for samples between 5 and 15 %. For the models based on these sample densities, the collected field data indicated an accuracy of predictive mapping close to 70 %.Informações digitais tornam possível um elevado grau de redundância das informações disponíveis para o ajuste de modelos preditores aplicados ao Mapeamento Digital de Solos (MDS. Entre esses modelos, a técnica de Árvores de Decisão (AD tem aplicação crescente, em razão da sua potência no tratamento de grandes volumes de dados. Objetivou-se com este trabalho avaliar o impacto do volume de dados utilizados para gerar os modelos por AD, na qualidade dos mapas de solos gerados pela técnica de MDS. Uma área de estudo com 889,33 km² foi escolhida na região do
Random fractional Fourier transform.
Liu, Zhengjun; Liu, Shutian
2007-08-01
We propose a novel random fractional Fourier transform by randomizing the transform kernel function of the conventional fractional Fourier transform. The random fractional Fourier transform inherits the excellent mathematical properties from the fractional Fourier transform and can be easily implemented in optics. As a primary application the random fractional Fourier transform can be directly used in optical image encryption and decryption. The double phase encoding image encryption schemes can thus be modeled with cascaded random fractional Fourier transformers.
Role of T1 Mapping in Inherited Cardiomyopathies.
Swoboda, Peter P; McDiarmid, Adam K; Page, Stephen P; Greenwood, John P; Plein, Sven
2016-01-01
T1 mapping by cardiovascular magnetic resonance is a rapidly evolving method for the quantitative assessment of tissue characteristics in cardiac disease. The myocardial T1 time can be measured without contrast (native T1) or following the administration of intravenous gadolinium-based contrast agent (post-contrast T1). By combining both of these measures, the myocardial extracellular volume fraction can be approximated. This value has been validated histologically in various inherited cardiomyopathies. Due to overlapping phenotypes, the diagnosis of inherited cardiomyopathy can at times be challenging. In this article we discuss when T1 mapping may be a useful tool in the differential diagnosis of cardiomyopathy. We also present evidence of when T1 mapping provides incremental risk stratification over other biomarkers.
A novel fractional sliding mode control configuration for ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 89; Issue 3. A novel fractional sliding mode ... In this paper, a new design of fractional-order sliding mode control scheme is proposed for the synchronization of a class of nonlinear fractional-order systems with chaotic behaviour. The considered design approach ...
Initialized Fractional Calculus
Lorenzo, Carl F.; Hartley, Tom T.
2000-01-01
This paper demonstrates the need for a nonconstant initialization for the fractional calculus and establishes a basic definition set for the initialized fractional differintegral. This definition set allows the formalization of an initialized fractional calculus. Two basis calculi are considered; the Riemann-Liouville and the Grunwald fractional calculi. Two forms of initialization, terminal and side are developed.
Energy Technology Data Exchange (ETDEWEB)
Sabzikar, Farzad, E-mail: sabzika2@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Meerschaert, Mark M., E-mail: mcubed@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Chen, Jinghua, E-mail: cjhdzdz@163.com [School of Sciences, Jimei University, Xiamen, Fujian, 361021 (China)
2015-07-15
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.
Hu, Chenxi; Sinusas, Albert J; Huber, Steffen; Thorn, Stephanie; Stacy, Mitchel R; Mojibian, Hamid; Peters, Dana C
2017-08-18
High resolution 3D T1 mapping is important for assessment of diffuse myocardial fibrosis in left atrium or other thin-walled structures. In this work, we investigated a fast single-TI 3D high resolution T1 mapping method that directly transforms a 3D late gadolinium enhancement (LGE) volume to a 3D T1 map. The proposed method, T1-refBlochi, is based on Bloch equation modeling of the LGE signal, a single-point calibration, and assumptions that proton density and T2* are relatively uniform in the heart. Several sources of error of this method were analyzed mathematically and with simulations. Imaging was performed in phantoms, eight swine and five patients, comparing T1-refBlochi to a standard spin-echo T1 mapping, 3D multi-TI T1 mapping, and 2D ShMOLLI, respectively. The method has a good accuracy and adequate precision, even considering various sources of error. In phantoms, over a range of protocols, heart-rates and T1 s, the bias ±1SD was -3 ms ± 9 ms. The porcine studies showed excellent agreement between T1-refBlochi and the multi-TI method (bias ±1SD = -6 ± 22 ms). The proton density and T2* weightings yielded ratios for scar/blood of 0.94 ± 0.01 and for myocardium/blood of 1.03 ± 0.02 in the eight swine, confirming that sufficient uniformity of proton density and T2* weightings exists among heterogeneous tissues of the heart. In the patients, the mean T1 bias ±1SD in myocardium and blood between T1-refBlochi and ShMOLLI was -9 ms ± 21 ms. T1-refBlochi provides a fast single-TI high resolution 3D T1 map of the heart with good accuracy and adequate precision.
Snyder, D. T.; Haluska, T. L.; Respini-Irwin, D.
2012-12-01
The Shoreline Management Tool is a GIS-based program developed to assist water- and land-resource managers in assessing the benefits and impacts of changes in surface-water stage on water depth, inundated area, and water volume. In addition, the tool can be used to identify aquatic or terrestrial habitat areas where conditions may be suitable for specific plants or animals as defined by user-specified criteria, including water depth, land-surface slope, and land-surface aspect or to delineate areas for use in determining a variety of hydrologic budget components such as surface-water storage, precipitation, runoff, or evapotranspiration. The Shoreline Management Tool consists of two parts, a graphical user interface for use with ArcMap GIS software to interact with the user to define scenarios and map results, and a spreadsheet in Microsoft Excel® developed to display tables and graphs of the results. The graphical user interface allows the user to define a scenario consisting of an inundation level (stage), land areas (parcels), and habitats (areas meeting user-specified conditions) based on water depth, slope, and aspect criteria. The tool uses data consisting of land-surface elevation, tables of stage/volume and stage/area, and delineated parcel boundaries to produce maps (data layers) of inundated areas and areas that meet the habitat criteria. The tool can be run in a Single-Time Scenario mode or in a Time-Series Scenario mode which uses an input file of dates and associated stages. The spreadsheet portion of the tool uses a macro to process the results from the graphical user interface to create tables and graphs of inundated water volume, inundated area, dry area, and mean water depth for each land parcel based on the user-specified stage. The macro also creates tables and graphs of the area, perimeter, and number of polygons comprising the user-specified habitat areas within each parcel. The Shoreline Management Tool is designed to be highly transferable
MEERSCHAERT, MARK M.; SABZIKAR, FARZAD; CHEN, JINGHUA
2014-01-01
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series. PMID:26085690
Meerschaert, Mark M; Sabzikar, Farzad; Chen, Jinghua
2015-07-15
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.
FRACTIONAL INTEGRATION TOOLBOX.
Marinov, Toma M; Ramirez, Nelson; Santamaria, Fidel
2013-09-01
The problems formulated in the fractional calculus framework often require numerical fractional integration/differentiation of large data sets. Several existing fractional control toolboxes are capable of performing fractional calculus operations, however, none of them can efficiently perform numerical integration on multiple large data sequences. We developed a Fractional Integration Toolbox (FIT), which efficiently performs fractional numerical integration/differentiation of the Riemann-Liouville type on large data sequences. The toolbox allows parallelization and is designed to be deployed on both CPU and GPU platforms.
Fleming, John; Conway, Joy; Majoral, Caroline; Bennett, Michael; Caillibotte, Georges; Montesantos, Spyridon; Katz, Ira
2014-07-25
Determination of regional lung air volume has several clinical applications. This study investigates the use of mid-tidal breathing CT scans to provide regional lung volume data. Low resolution CT scans of the thorax were obtained during tidal breathing in 11 healthy control male subjects, each on two separate occasions. A 3D map of air volume was derived, and total lung volume calculated. The regional distribution of air volume from centre to periphery of the lung was analysed using a radial transform and also using one dimensional profiles in three orthogonal directions. The total air volumes for the right and left lungs were 1035 +/- 280 ml and 864 +/- 315 ml, respectively (mean and SD). The corresponding fractional air volume concentrations (FAVC) were 0.680 +/- 0.044 and 0.658 +/- 0.062. All differences between the right and left lung were highly significant (p lung air volumes and FAVC were 6.5% and 6.9% and 2.5% and 3.6%, respectively. FAVC correlated significantly with lung space volume (r = 0.78) (p lung. Central to peripheral ratios were significantly higher for the right (0.100 +/- 0.007 SD) than the left (0.089 +/- 0.013 SD) (p volume in the lung at mid-tidal breathing is described. Mean values and reproducibility are described for healthy male control subjects. Fractional air volume concentration is shown to increase with lung size.
Applications of fractional calculus in physics
2000-01-01
Fractional calculus is a collection of relatively little-known mathematical results concerning generalizations of differentiation and integration to noninteger orders. While these results have been accumulated over centuries in various branches of mathematics, they have until recently found little appreciation or application in physics and other mathematically oriented sciences. This situation is beginning to change, and there are now a growing number of research areas in physics which employ fractional calculus.This volume provides an introduction to fractional calculus for physicists, and co
Energy Technology Data Exchange (ETDEWEB)
Filss, Christian P., E-mail: c.filss@fz-juelich.de [Institute of Neuroscience and Medicine (INM-3,-4,-5), Research Center Jülich, Jülich (Germany); Stoffels, Gabriele [Institute of Neuroscience and Medicine (INM-3,-4,-5), Research Center Jülich, Jülich (Germany); Galldiks, Norbert [Institute of Neuroscience and Medicine (INM-3,-4,-5), Research Center Jülich, Jülich (Germany); Department of Neurology, University of Cologne, Cologne (Germany); Sabel, Michael [Department of Neurosurgery, University Düsseldorf, Medical Faculty, Düsseldorf (Germany); Wittsack, Hans J. [Department of Diagnostic and Interventional Radiology, University Düsseldorf, Medical Faculty, Düsseldorf (Germany); Coenen, Heinz H. [Institute of Neuroscience and Medicine (INM-3,-4,-5), Research Center Jülich, Jülich (Germany); Jülich-Aachen Research Alliance (JARA) – Section JARA-Brain (Germany); Shah, Nadim J. [Institute of Neuroscience and Medicine (INM-3,-4,-5), Research Center Jülich, Jülich (Germany); Jülich-Aachen Research Alliance (JARA) – Section JARA-Brain (Germany); Department of Neurology, RWTH Aachen University Hospital, Aachen (Germany); Herzog, Hans [Institute of Neuroscience and Medicine (INM-3,-4,-5), Research Center Jülich, Jülich (Germany); Jülich-Aachen Research Alliance (JARA) – Section JARA-Brain (Germany); and others
2014-01-11
Anatomical imaging with magnetic resonance imaging (MRI) is currently the method of first choice for diagnostic investigation of glial tumors. However, different MR sequences may over- or underestimate tumor size and thus it may not be possible to delineate tumor from adjacent brain. In order to compensate this confinement additonal MR sequences like perfusion weighted MRI (PWI) with regional cerebral blood volume (rCBV) or positron emission tomography (PET) with aminoacids are used to gain further information. Recent studies suggest that both of theses image modalities provide similar diagnostic information. For comparison tumor to brain ratios (TBR) with mean and maximum values are frequently used but results from different studies can often not be checked against each other. Furthermore, especially the maximum TBR in rCBV is at risk to be falsified by artifacts (e.g. blood vessels). These confinements are reduced by the use of histograms since all information of the VOIs are equally displayed. In this study we measured and compared the intersection of tumor and reference tissue histograms in {sup 18}F-FET PET and rCBV maps in glioma patients. Methods: Twenty-seven glioma patients with contrast enhancing lesion on T1-weighted MR images were investigated using static {sup 18}F-FET PET and rCBV in MRI using a PET–MR hybrid scanner. In all patients diagnosis was confirmed histologically (7 grade II gliomas, 6 grade III gliomas and 14 grade IV gliomas). We generated a set of tumor and reference tissue Volumes-of-Interest (VOIs) based on T1 weighted images in MRI with the tumor VOI defined by contrast enhancement and transferred these VOIs to the corresponding {sup 18}F-FET PET scans and rCBV maps. From these VOIs we generated tumor and reference tissue histograms with a unity of one for each curve integral and measured the proportion of the area under the tumor curve that falls into the reference curve for {sup 18}F-FET PET and rCBV maps for each patient. Results
Dewi, D. A. K.; Suryadi, D.; Suratno, T.; Mulyana, E.; Kurniawan, H.
2017-02-01
Introducing fractions is identical to divide an object. Suppose we divide the apple into two parts. One divided into two parts, the question arises whether one part can be called a half or not. Based on this activity, how can students give meaning to fractions. This study aims at designing a different fractions lesson by applying Didactical Design Research. In doing so, we undertook several research phases: 1) thinking what is fractions and why students should learn this concept; 2) designing didactical situation based on identified learning obstacles; and 3) reflecting retrospectively on the lesson design and its implementation as to redesign the fractions lesson. Our analysis revealed that most students held epistemological obstacles in giving meaning of fractions because they only know fractions as numbers that have numerator and denominator. By positioning ourselves as students, we discuss the ideal design to help students in constructing the meaning of fractions.
Fractional Multidimensional System
Zhu, Xiaogang; Lu, Junguo
2017-01-01
The multidimensional ($n$-D) systems described by Roesser model are presented in this paper. These $n$-D systems consist of discrete systems and continuous fractional order systems with fractional order $\
Sisk, Diane
This autoinstructional program, developed as part of a general science course, is offered for students in the middle schools. Mathematics of fractions and decimals is considered to be prerequisite knowledge. The behavioral objectives are directed toward mastery of determining volumes of solid objects using the water displacement method as well as…
MEERSCHAERT, MARK M.; SABZIKAR, FARZAD; CHEN, JINGHUA
2015-01-01
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly obs...
DEFF Research Database (Denmark)
Goerres, Achim; Vanhuysse, Pieter
2012-01-01
Whereas the call for a political science based study of older people and ageing is not new (Cutler 1977; Heclo 1988), relatively little unified progress has been made so far. This chapter maps the field of generational politics and introduces our edited volume "Ageing Populations in Post-Industri......Whereas the call for a political science based study of older people and ageing is not new (Cutler 1977; Heclo 1988), relatively little unified progress has been made so far. This chapter maps the field of generational politics and introduces our edited volume "Ageing Populations in Post...
Observability of Nonlinear Fractional Dynamical Systems
Directory of Open Access Journals (Sweden)
K. Balachandran
2013-01-01
Full Text Available We study the observability of linear and nonlinear fractional differential systems of order 0<α<1 by using the Mittag-Leffler matrix function and the application of Banach’s contraction mapping theorem. Several examples illustrate the concepts.
On continued fraction algorithms
Smeets, Ionica
2010-01-01
Is there a good continued fraction approximation between every two bad ones? What is the entropy of the natural extension for alpha-Rosen fractions? How do you find multi-dimensional continued fractions with a guaranteed quality in polynomial time? These, and many more, questions are answered in
Nonlinear fractional relaxation
Indian Academy of Sciences (India)
Nonlinear fractional equation; nonlinear fractional relaxation; -expansion. Abstract. We deﬁne a nonlinear model for fractional relaxation phenomena. We use -expansion method to analyse this model. By studying the fundamental solutions of this model we ﬁnd that when → 0 the model exhibits a fast decay rate and ...
Unfolding Fraction Multiplication
Wyberg, Terry; Whitney, Stephanie R.; Cramer, Kathleen A.; Monson, Debra S.; Leavitt, Seth
2011-01-01
Students often have difficulty understanding fractions, in general, and understanding how to multiply fractions, in particular. To move past this potential problem area, students need to develop a deeper understanding of multiplication and connect the ideas to fractions. In this article, the authors share their insights into teaching fraction…
Snyder, Daniel T.; Haluska, Tana L.; Respini-Irwin, Darius
2013-01-01
The Shoreline Management Tool is a geographic information system (GIS) based program developed to assist water- and land-resource managers in assessing the benefits and effects of changes in surface-water stage on water depth, inundated area, and water volume. Additionally, the Shoreline Management Tool can be used to identify aquatic or terrestrial habitat areas where conditions may be suitable for specific plants or animals as defined by user-specified criteria including water depth, land-surface slope, and land-surface aspect. The tool can also be used to delineate areas for use in determining a variety of hydrologic budget components such as surface-water storage, precipitation, runoff, or evapotranspiration. The Shoreline Management Tool consists of two parts, a graphical user interface for use with Esri™ ArcMap™ GIS software to interact with the user to define scenarios and map results, and a spreadsheet in Microsoft® Excel® developed to display tables and graphs of the results. The graphical user interface allows the user to define a scenario consisting of an inundation level (stage), land areas (parcels), and habitats (areas meeting user-specified conditions) based on water depth, slope, and aspect criteria. The tool uses data consisting of land-surface elevation, tables of stage/volume and stage/area, and delineated parcel boundaries to produce maps (data layers) of inundated areas and areas that meet the habitat criteria. The tool can be run in a Single-Time Scenario mode or in a Time-Series Scenario mode, which uses an input file of dates and associated stages. The spreadsheet part of the tool uses a macro to process the results from the graphical user interface to create tables and graphs of inundated water volume, inundated area, dry area, and mean water depth for each land parcel based on the user-specified stage. The macro also creates tables and graphs of the area, perimeter, and number of polygons comprising the user-specified habitat areas
Fractional Differential Equations
Directory of Open Access Journals (Sweden)
Jianping Zhao
2012-01-01
Full Text Available An extended fractional subequation method is proposed for solving fractional differential equations by introducing a new general ansätz and Bäcklund transformation of the fractional Riccati equation with known solutions. Being concise and straightforward, this method is applied to the space-time fractional coupled Burgers’ equations and coupled MKdV equations. As a result, many exact solutions are obtained. It is shown that the considered method provides a very effective, convenient, and powerful mathematical tool for solving fractional differential equations.
Shamim, Atif
2011-03-01
For the first time, a generalized Smith chart is introduced here to represent fractional order circuit elements. It is shown that the standard Smith chart is a special case of the generalized fractional order Smith chart. With illustrations drawn for both the conventional integer based lumped elements and the fractional elements, a graphical technique supported by the analytical method is presented to plot impedances on the fractional Smith chart. The concept is then applied towards impedance matching networks, where the fractional approach proves to be much more versatile and results in a single element matching network for a complex load as compared to the two elements in the conventional approach. © 2010 IEEE.
Fractional Dynamics and Control
Machado, José; Luo, Albert
2012-01-01
Fractional Dynamics and Control provides a comprehensive overview of recent advances in the areas of nonlinear dynamics, vibration and control with analytical, numerical, and experimental results. This book provides an overview of recent discoveries in fractional control, delves into fractional variational principles and differential equations, and applies advanced techniques in fractional calculus to solving complicated mathematical and physical problems.Finally, this book also discusses the role that fractional order modeling can play in complex systems for engineering and science. Discusses how fractional dynamics and control can be used to solve nonlinear science and complexity issues Shows how fractional differential equations and models can be used to solve turbulence and wave equations in mechanics and gravity theories and Schrodinger’s equation Presents factional relaxation modeling of dielectric materials and wave equations for dielectrics Develops new methods for control and synchronization of...
Dey, Aloke
2009-01-01
A one-stop reference to fractional factorials and related orthogonal arrays.Presenting one of the most dynamic areas of statistical research, this book offers a systematic, rigorous, and up-to-date treatment of fractional factorial designs and related combinatorial mathematics. Leading statisticians Aloke Dey and Rahul Mukerjee consolidate vast amounts of material from the professional literature--expertly weaving fractional replication, orthogonal arrays, and optimality aspects. They develop the basic theory of fractional factorials using the calculus of factorial arrangements, thereby providing a unified approach to the study of fractional factorial plans. An indispensable guide for statisticians in research and industry as well as for graduate students, Fractional Factorial Plans features: * Construction procedures of symmetric and asymmetric orthogonal arrays. * Many up-to-date research results on nonexistence. * A chapter on optimal fractional factorials not based on orthogonal arrays. * Trend-free plans...
Fractional graph theory a rational approach to the theory of graphs
Scheinerman, Edward R
2013-01-01
A unified treatment of the most important results in the study of fractional graph concepts, this volume explores the various ways in which integer-valued concepts can be modified to derive nonintegral values. It begins with the general fractional theory of hypergraphs and presents in-depth coverage of fundamental and advanced topics. Subjects include fractional matching, fractional coloring, fractional edge coloring, fractional arboricity via matroid methods, and fractional isomorphism. The final chapter examines additional topics such as fractional domination, fractional intersection numbers
Bohnen, Sebastian; Radunski, Ulf K; Lund, Gunnar K; Kandolf, Reinhard; Stehning, Christian; Schnackenburg, Bernhard; Adam, Gerhard; Blankenberg, Stefan; Muellerleile, Kai
2015-06-01
This study evaluated the performance of novel quantitative T1 and T2 mapping cardiovascular magnetic resonance (CMR) techniques to identify active myocarditis in patients with recent-onset heart failure. Thirty-one consecutive patients with recent-onset heart failure, reduced left ventricular function and clinically suspected myocarditis underwent endomyocardial biopsy and CMR at 1.5 Tesla. The CMR protocol included standard Lake-Louise parameters as well as T1 mapping using a modified Look-Locker inversion recovery sequence and T2 mapping using a hybrid gradient and spin-echo sequence. Short-axis maps were generated using an OsiriX plug-in to calculate global myocardial T1, T2, and extracellular volume fraction. Active myocarditis was defined by ongoing inflammation on endomyocardial biopsy. Endomyocardial biopsy revealed active myocarditis in 16 (52%) of 31 patients. Neither clinical characteristics, standard Lake-Louise CMR parameters, global myocardial T1 nor extracellular volume fraction differed significantly between patients with and without active myocarditis. However, median global myocardial T2 was significantly higher in patients with active myocarditis (65 ms [Q1-Q3, 61-70 ms]) than in patients without active myocarditis (59 ms [Q1-Q3, 55-64 ms]; Psuperior when compared with standard CMR parameters, global myocardial T1, and extracellular volume fraction values for assessing the activity of myocarditis in patients with recent-onset heart failure and reduced left ventricular function. © 2015 American Heart Association, Inc.
Dividing Fractions: A Pedagogical Technique
Lewis, Robert
2016-01-01
When dividing one fraction by a second fraction, invert, that is, flip the second fraction, then multiply it by the first fraction. To multiply fractions, simply multiply across the denominators, and multiply across the numerators to get the resultant fraction. So by inverting the division of fractions it is turned into an easy multiplication of…
Directory of Open Access Journals (Sweden)
Edmundo Arteaga
2009-03-01
ó, con éxito, biopsia endomiocárdica del ventrículo derecho en 21 pacientes sintomáticos con CMH. La fracción de volumen de colágeno (FVC miocárdico se determinó por medio de histología. Se determinó la FVC también en fragmentos de nueve corazones normales de individuos fallecidos por causas no cardiacas. Respecto a la FVC, se dividieron a los pacientes en grupos supra e inframedianos (FVC elevada y FVC baja, respectivamente, y se compararon las características clínicas y ecocardiográficas y las curvas de sobrevida. RESULTADOS: Entre los pacientes, la FVC tuvo variación del 1,86% al 29,9%, con mediana en el 6,19%. Ya en los corazones normales, del 0,13% al 1,46%, mediana en el 0,36% (p6,19%, sin que se observara diferencias basales. Sin embargo, tras un período de seguimiento promedio de 110 meses, cuatro muertes ocurrieron (dos súbitas, y otras dos por insuficiencia cardiaca en el grupo con FVC mayor, mientras que los pacientes del grupo con FVC menor estaban vivos al final del período (p=0,02. CONCLUSIÓN: Por primera vez, se asoció prospectivamente la fibrosis miocárdica a un peor diagnóstico en pacientes con CMH. Se deben encaminar esfuerzos hacia la cuantificación de la fibrosis en la CMH, al aceptar que la asociación con el pronóstico puede auxiliar tanto en la estratificación de riesgo para implante de desfibrilador, como en la prescripción de fármacos potencialmente reparadores miocárdicos.BACKGROUND: In hypertrophic cardiomyopathy (HCM, interstitial myocardial fibrosis is an important histological modification that has been associated with sudden death and evolution toward myocardial dilation. OBJECTIVE:To prospectively evaluate the prognostic value of the collagen volume fraction in HCM. METHODS: An endomyocardial biopsy of the right ventricle was successfully performed in 21 symptomatic patients with HCM. The myocardial collagen volume fraction (CVF was determined by histology. The CVF was also determined in fragments of nine normal
Takemura, A.; Harauchi, H.; Suzuki, M.; Hoffmann, K. R.; Inamura, K.; Umeda, T.
2003-08-01
This paper proposes an algorithm which maps the position of a catheter tip on a fluorograph to the 3D position in magnetic resonance angiography (MRA) data. This algorithm was assessed for its accuracy. We designed an algorithm consisting of a registration step and a recognition step. The registration step registers MRA and fluorography data using a digital subtraction angiography (DSA) image. The recognition step recognizes the position in the MRA data corresponding to the catheter tip position on a fluorograph. We checked the accuracy of the recognition step by employing an artificial data set consisting of 3D image data (64 × 64 × 64 matrix) and its projection image (92 × 92 matrix) and the accuracy of the registration step with the aid of three of the 3D time-of-flight MRA data sets (256 × 256 matrix and 60 slices) and their projection images in the form of DSA images. The accuracy of the recognition step depended upon that of the registration. When there was no misregistration, all of the mean errors were less than 0.2 mm. The mean errors of the registration step were 0.273 mm and 0.226 mm, respectively, for the longitudinal shift along the X and Y axes, 0.478°, 1.203° and 0.208°, respectively, for the rotation angles around the X, Y and Z axes and 0.020 times for the magnification. The mean image error between the projection image of the registered MRA data and that of the MRA data which were employed as the DSA image was 0.034 mm.
Generalized Smooth Transition Map Between Tent and Logistic Maps
Sayed, Wafaa S.; Fahmy, Hossam A. H.; Rezk, Ahmed A.; Radwan, Ahmed G.
There is a continuous demand on novel chaotic generators to be employed in various modeling and pseudo-random number generation applications. This paper proposes a new chaotic map which is a general form for one-dimensional discrete-time maps employing the power function with the tent and logistic maps as special cases. The proposed map uses extra parameters to provide responses that fit multiple applications for which conventional maps were not enough. The proposed generalization covers also maps whose iterative relations are not based on polynomials, i.e. with fractional powers. We introduce a framework for analyzing the proposed map mathematically and predicting its behavior for various combinations of its parameters. In addition, we present and explain the transition map which results in intermediate responses as the parameters vary from their values corresponding to tent map to those corresponding to logistic map case. We study the properties of the proposed map including graph of the map equation, general bifurcation diagram and its key-points, output sequences, and maximum Lyapunov exponent. We present further explorations such as effects of scaling, system response with respect to the new parameters, and operating ranges other than transition region. Finally, a stream cipher system based on the generalized transition map validates its utility for image encryption applications. The system allows the construction of more efficient encryption keys which enhances its sensitivity and other cryptographic properties.
Complex Transforms for Systems of Fractional Differential Equations
Directory of Open Access Journals (Sweden)
Rabha W. Ibrahim
2012-01-01
Full Text Available We provide a complex transform that maps the complex fractional differential equation into a system of fractional differential equations. The homogeneous and nonhomogeneous cases for equivalence equations are discussed and also nonequivalence equations are studied. Moreover, the existence and uniqueness of solutions are established and applications are illustrated.
Kitchin, Rob
2001-01-01
A cognitive map is a representative expression of an individual's cognitive map knowledge, where cognitive map knowledge is an individual's knowledge about the spatial and environmental relations of geographic space. For example, a sketch map drawn to show the route between two locations is a cognitive map — a representative expression of the drawer's knowledge of the route between the two locations. This map can be analyzed using classification schemes or quantitatively using spatial statist...
FRACTIONAL PEARSON DIFFUSIONS.
Leonenko, Nikolai N; Meerschaert, Mark M; Sikorskii, Alla
2013-07-15
Pearson diffusions are governed by diffusion equations with polynomial coefficients. Fractional Pearson diffusions are governed by the corresponding time-fractional diffusion equation. They are useful for modeling sub-diffusive phenomena, caused by particle sticking and trapping. This paper provides explicit strong solutions for fractional Pearson diffusions, using spectral methods. It also presents stochastic solutions, using a non-Markovian inverse stable time change.
Directory of Open Access Journals (Sweden)
Sally L Collins
Full Text Available To undertake an observational study to see whether first trimester placental vascularity, measured with a standardized power Doppler index: 3D-FMBV, is different in pregnancies which either develop pre-eclampsia or lead to term, normotensive small for gestational age (SGA babies.Women were scanned between 11 and 13+6 weeks. The placental volume (sPlaV was estimated using our previously validated semi-automated tool. Estimates of 3D-FMBV were generated from the raw power Doppler signal for the whole utero-placental interface, UPI (FMBV-UPI and 5mm into the placenta (FMBV-IVS. Differences in the placental volume and FMBV for pregnancies developing pre-eclampsia and resulting in term, normotensive SGA babies were compared with term, normotensive, appropriate for gestational age (AGA, controls.Results were available for 143 women. The placental volume (sPlaV was reduced in both pre-eclampsia (p = 0.007 and term, normotensive SGA (p = 0.001 when compared with term normotensive AGA controls. 3D-FMBV estimates were significantly lower for pregnancies developing pre-eclampsia (FMBV-UPI, p = 0.03, FMBV-IVS, p = 0.01 but not for the normotensive SGA pregnancies (FMBV-UPI, p = 0.16, FMBV-IVS, p = 0.27.Pregnancies destined to develop pre-eclampsia are more likely to have small placentas with significantly reduced vascularity at 11-13 weeks. Those pregnancies which were normotensive throughout but resulted in an SGA baby delivered at term, had significantly smaller placentas but with similar vascularity to normotensive AGA pregnancies.
Knowledge Map of Facilities Management
DEFF Research Database (Denmark)
Nenonen, Suvi; Jensen, Per Anker; Lindahl, Göran
2014-01-01
Purpose This paper aims to draft a knowledge map of the fragmented and multidisciplinary research of and relevant to FM. Facilities management knowledge map is a tool for presenting what relevant data and knowledge, a.k.a. knowledge, resides in different disciplines. Knowledge mapping is a step...... in creating an inventory of knowledge (i.e. the knowledge base) and developing/improving the processes of knowledge sharing in research, education and practice. Theory Knowledge mapping is discussed in terms of knowledge management. The research is connected to knowledge mapping in the facilities management...... profession, research and education. The knowledge map aims to contrast perspectives on how to map interdisciplinary research. Design/methodology/approach The Knowledge map is based on classification of 83 articles, including volume 2013 of Facilities (40 articles) and of Journal of Facilities Management (21...
Karthikeyan, Anitha; Rajagopal, Karthikeyan
2018-01-01
A new fourth-order memristor chaotic oscillator is taken to investigate its fractional-order discrete synchronisation. The fractional-order differential model memristor system is transformed to its discrete model and the dynamic properties of the fractional-order discrete system are investigated. A new method for synchronising commensurate and incommensurate fractional discrete chaotic maps are proposed and validated. Numerical results are established to support the proposed methodologies. This method of synchronisation can be applied for any fractional discrete maps. Finally the fractional-order memristor system is implemented in FPGA to show that the chaotic system is hardware realisable.
Can Kindergartners Do Fractions?
Cwikla, Julie
2014-01-01
Mathematics professor Julie Cwikla decided that she needed to investigate young children's understandings and see what precurricular partitioning notions young minds bring to the fraction table. Cwikla realized that only a handful of studies have examined how preschool-age and early elementary school-age students solve fraction problems (Empson…
Callison, Daniel
2001-01-01
Explains concept mapping as a heuristic device that is helpful in visualizing the relationships between and among ideas. Highlights include how to begin a map; brainstorming; map applications, including document or information summaries and writing composition; and mind mapping to strengthen note-taking. (LRW)
Filss, Christian P.; Stoffels, Gabriele; Galldiks, Norbert; Sabel, Michael; Wittsack, Hans J.; Coenen, Heinz H.; Shah, Nadim J.; Herzog, Hans; Langen, Karl-Josef
2014-01-01
Anatomical imaging with magnetic resonance imaging (MRI) is currently the method of first choice for diagnostic investigation of glial tumors. However, different MR sequences may over- or underestimate tumor size and thus it may not be possible to delineate tumor from adjacent brain. In order to compensate this confinement additonal MR sequences like perfusion weighted MRI (PWI) with regional cerebral blood volume (rCBV) or positron emission tomography (PET) with aminoacids are used to gain further information. Recent studies suggest that both of theses image modalities provide similar diagnostic information. For comparison tumor to brain ratios (TBR) with mean and maximum values are frequently used but results from different studies can often not be checked against each other. Furthermore, especially the maximum TBR in rCBV is at risk to be falsified by artifacts (e.g. blood vessels). These confinements are reduced by the use of histograms since all information of the VOIs are equally displayed. In this study we measured and compared the intersection of tumor and reference tissue histograms in 18F-FET PET and rCBV maps in glioma patients.
DEFF Research Database (Denmark)
Mogensen, O.; Sørensen, Flemming Brandt; Bichel, P.
1999-01-01
We evaluated the following nine parameters with respect to their prognostic value in females with endometrial cancer: four stereologic parameters [mean nuclear volume (MNV), nuclear volume fraction, nuclear index and mitotic index], the immunohistochemical expression of cancer antigen (CA125...... (range 5.0-8.4 years). Cox regression analysis (automatic forward selection) showed the MNV to be the most significant prognostic parameter followed by the P-stage. Patients who had localized tumors or tumors with small nuclei had a better probability of surviving than did women with advanced tumors...
Schwendimann, Beat Adrian
2014-01-01
A concept map is a node-link diagram showing the semantic relationships among concepts. The technique for constructing concept maps is called "concept mapping". A concept map consists of nodes, arrows as linking lines, and linking phrases that describe the relationship between nodes. Two nodes connected with a labeled arrow are called a proposition. Concept maps are versatile graphic organizers that can represent many different forms of relationships between concepts. The relationship between...
Fractional Dynamics Applications of Fractional Calculus to Dynamics of Particles, Fields and Media
Tarasov, Vasily E
2010-01-01
"Fractional Dynamics: Applications of Fractional Calculus to Dynamics of Particles, Fields and Media" presents applications of fractional calculus, integral and differential equations of non-integer orders in describing systems with long-time memory, non-local spatial and fractal properties. Mathematical models of fractal media and distributions, generalized dynamical systems and discrete maps, non-local statistical mechanics and kinetics, dynamics of open quantum systems, the hydrodynamics and electrodynamics of complex media with non-local properties and memory are considered. This book is intended to meet the needs of scientists and graduate students in physics, mechanics and applied mathematics who are interested in electrodynamics, statistical and condensed matter physics, quantum dynamics, complex media theories and kinetics, discrete maps and lattice models, and nonlinear dynamics and chaos. Dr. Vasily E. Tarasov is a Senior Research Associate at Nuclear Physics Institute of Moscow State University and...
Simplified fractional Fourier transforms.
Pei, S C; Ding, J J
2000-12-01
The fractional Fourier transform (FRFT) has been used for many years, and it is useful in many applications. Most applications of the FRFT are based on the design of fractional filters (such as removal of chirp noise and the fractional Hilbert transform) or on fractional correlation (such as scaled space-variant pattern recognition). In this study we introduce several types of simplified fractional Fourier transform (SFRFT). Such transforms are all special cases of a linear canonical transform (an affine Fourier transform or an ABCD transform). They have the same capabilities as the original FRFT for design of fractional filters or for fractional correlation. But they are simpler than the original FRFT in terms of digital computation, optical implementation, implementation of gradient-index media, and implementation of radar systems. Our goal is to search for the simplest transform that has the same capabilities as the original FRFT. Thus we discuss not only the formulas and properties of the SFRFT's but also their implementation. Although these SFRFT's usually have no additivity properties, they are useful for the practical applications. They have great potential for replacing the original FRFT's in many applications.
FPGA implementation of fractional-order discrete memristor chaotic ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 90; Issue 1. FPGA implementation of fractional-order discrete memristor chaotic system and its commensurate and incommensurate synchronisations. ANITHA KARTHIKEYAN KARTHIKEYAN RAJAGOPAL. Research Article Volume 90 Issue 1 January 2018 Article ID ...
Fractional calculus in bioengineering.
Magin, Richard L
2004-01-01
Fractional calculus (integral and differential operations of noninteger order) is not often used to model biological systems. Although the basic mathematical ideas were developed long ago by the mathematicians Leibniz (1695), Liouville (1834), Riemann (1892), and others and brought to the attention of the engineering world by Oliver Heaviside in the 1890s, it was not until 1974 that the first book on the topic was published by Oldham and Spanier. Recent monographs and symposia proceedings have highlighted the application of fractional calculus in physics, continuum mechanics, signal processing, and electromagnetics, but with few examples of applications in bioengineering. This is surprising because the methods of fractional calculus, when defined as a Laplace or Fourier convolution product, are suitable for solving many problems in biomedical research. For example, early studies by Cole (1933) and Hodgkin (1946) of the electrical properties of nerve cell membranes and the propagation of electrical signals are well characterized by differential equations of fractional order. The solution involves a generalization of the exponential function to the Mittag-Leffler function, which provides a better fit to the observed cell membrane data. A parallel application of fractional derivatives to viscoelastic materials establishes, in a natural way, hereditary integrals and the power law (Nutting/Scott Blair) stress-strain relationship for modeling biomaterials. In this review, I will introduce the idea of fractional operations by following the original approach of Heaviside, demonstrate the basic operations of fractional calculus on well-behaved functions (step, ramp, pulse, sinusoid) of engineering interest, and give specific examples from electrochemistry, physics, bioengineering, and biophysics. The fractional derivative accurately describes natural phenomena that occur in such common engineering problems as heat transfer, electrode/electrolyte behavior, and sub
T1 and T2 Mapping in Cardiology: "Mapping the Obscure Object of Desire".
Mavrogeni, Sophie; Apostolou, Dimitris; Argyriou, Panayiotis; Velitsista, Stella; Papa, Lilika; Efentakis, Stelios; Vernardos, Evangelos; Kanoupaki, Mikela; Kanoupakis, George; Manginas, Athanassios
2017-08-17
The increasing use of cardiovascular magnetic resonance (CMR) is based on its capability to perform biventricular function assessment and tissue characterization without radiation and with high reproducibility. The use of late gadolinium enhancement (LGE) gave the potential of non-invasive biopsy for fibrosis quantification. However, LGE is unable to detect diffuse myocardial disease. Native T1 mapping and extracellular volume fraction (ECV) provide knowledge about pathologies affecting both the myocardium and interstitium that is otherwise difficult to identify. Changes of myocardial native T1 reflect cardiac diseases (acute coronary syndromes, infarction, myocarditis, and diffuse fibrosis, all with high T1) and systemic diseases such as cardiac amyloid (high T1), Anderson-Fabry disease (low T1), and siderosis (low T1). The ECV, an index generated by native and post-contrast T1 mapping, measures the cellular and extracellular interstitial matrix (ECM) compartments. This myocyte-ECM dichotomy has important implications for identifying specific therapeutic targets of great value for heart failure treatment. On the other hand, T2 mapping is superior compared with myocardial T1 and ECM for assessing the activity of myocarditis in recent-onset heart failure. Although these indices can significantly affect the clinical decision making, multicentre studies and a community-wide approach (including MRI vendors, funding, software, contrast agent manufacturers, and clinicians) are still missing. © 2017 S. Karger AG, Basel.
Fractional finite Fourier transform.
Khare, Kedar; George, Nicholas
2004-07-01
We show that a fractional version of the finite Fourier transform may be defined by using prolate spheroidal wave functions of order zero. The transform is linear and additive in its index and asymptotically goes over to Namias's definition of the fractional Fourier transform. As a special case of this definition, it is shown that the finite Fourier transform may be inverted by using information over a finite range of frequencies in Fourier space, the inversion being sensitive to noise. Numerical illustrations for both forward (fractional) and inverse finite transforms are provided.
Social Trust and Fractionalization:
DEFF Research Database (Denmark)
Bjørnskov, Christian
2008-01-01
This paper takes a closer look at the importance of fractionalization for the creation of social trust. It first argues that the determinants of trust can be divided into two categories: those affecting individuals' trust radii and those affecting social polarization. A series of estimates using...... a much larger country sample than in previous literature confirms that fractionalization in the form of income inequality and political diversity adversely affects social trust while ethnic diversity does not. However, these effects differ systematically across countries, questioning standard...... interpretations of the influence of fractionalization on trust....
DEFF Research Database (Denmark)
Andersen, Andreas G; Casares-Magaz, Oscar; Muren, Ludvig P
2015-01-01
BACKGROUND: The benefit of proton therapy may be jeopardized by dose deterioration caused by water equivalent path length (WEPL) variations. In this study we introduced a method to evaluate robustness of proton therapy with respect to inter-fractional motion and applied it to irradiation of the p......BACKGROUND: The benefit of proton therapy may be jeopardized by dose deterioration caused by water equivalent path length (WEPL) variations. In this study we introduced a method to evaluate robustness of proton therapy with respect to inter-fractional motion and applied it to irradiation......) to the planning target volume (PTV) were investigated. The optimized fluence maps for the pCT for each beam were applied onto all rCTs and the dose distributions were re-calculated. WEPL variation for each beam angle was computed by averaging over beams eye view WEPL distributions. RESULTS: Similarity...
White matter microstructure from nonparametric axon diameter distribution mapping.
Benjamini, Dan; Komlosh, Michal E; Holtzclaw, Lynne A; Nevo, Uri; Basser, Peter J
2016-07-15
We report the development of a double diffusion encoding (DDE) MRI method to estimate and map the axon diameter distribution (ADD) within an imaging volume. A variety of biological processes, ranging from development to disease and trauma, may lead to changes in the ADD in the central and peripheral nervous systems. Unlike previously proposed methods, this ADD experimental design and estimation framework employs a more general, nonparametric approach, without a priori assumptions about the underlying form of the ADD, making it suitable to analyze abnormal tissue. In the current study, this framework was used on an ex vivo ferret spinal cord, while emphasizing the way in which the ADD can be weighted by either the number or the volume of the axons. The different weightings, which result in different spatial contrasts, were considered throughout this work. DDE data were analyzed to derive spatially resolved maps of average axon diameter, ADD variance, and extra-axonal volume fraction, along with a novel sub-micron restricted structures map. The morphological information contained in these maps was then used to segment white matter into distinct domains by using a proposed k-means clustering algorithm with spatial contiguity and left-right symmetry constraints, resulting in identifiable white matter tracks. The method was validated by comparing histological measures to the estimated ADDs using a quantitative similarity metric, resulting in good agreement. With further acquisition acceleration and experimental parameters adjustments, this ADD estimation framework could be first used preclinically, and eventually clinically, enabling a wide range of neuroimaging applications for improved understanding of neurodegenerative pathologies and assessing microstructural changes resulting from trauma. Published by Elsevier Inc.
Emmett, Louise; Ng, Austin; Ha, Leo; Russo, Robert; Mansberg, Robert; Zhao, Wei; Chow, S Vincent; Kritharides, Leonard
2012-08-01
Transient ischaemic dilation (TID) on myocardial perfusion imaging (MPI) is an important finding, conveying a high risk of subsequent cardiac events. However, the mechanism leading to TID on MPI is not well elucidated. This study aimed to determine if TID is due to true LV cavity dilation and ventricular stunning, or is due to relative subendocardial hypoperfusion. 31 patients undergoing single-day Tc-99m adenosine sestamibi MPI were recruited. All had routine ECG-gated single-day rest-stress adenosine MPI, with transthoracic echocardiograms (echo) acquired concurrently at rest, and both immediately, and 2 hours, post-stress. Echocardiography was performed using a Vivid-7 (GE). LV volumes and LVEF were quantified blinded to MPI results, using biplane Simpson method on echo, and quantitatively (including TID) with QGS(®), on MPI. Patients were divided into quartiles for TID, with the top quartile considered TID positive [TID+ 9/31 (TID ratio 1.3 ± 0.09)], and TID negative [TID- 22/31 (TID ratio 1.01 ± 0.04)]. There was good correlation between resting echo and MPI physical measurements (LVEDV r(2) = 0.79, LVESV r(2) = 0.9, and LVEF r(2) = 0.75). On MPI, a significant drop in LVEF was observed between rest and early stress in the TID+ group (56.6% vs 46.5%, P subendocardial hypoperfusion and impaired coronary flow reserve.
Energy Technology Data Exchange (ETDEWEB)
Ziada, G.; Abdel-Dayem, H.M.; Higazy, E.; Mohamed, M.M.; Bahar, R.; Hayat, N.; Yousof, A.M.
1987-03-01
A dual gated tomography (DGT) program for end systolic and end diastolic acquisition and subsequent processing for calculation of LVEF, end diastolic and end systolic volumes (EDV, ESV) has been evaluated in 20 healthy volunteers (25 years-40 years) and 45 patients (25 years-60 years): 20 with ischaemic heart disease and 25 with valvular heart disease (VHD). All had biplane multigated blood pool (MUGA) studies in the 40/sup 0/ LAO projection using in vivo /sup 99m/Tc-R BCs, immediately followed by DG. The results in the patients group were correlated with contrast ventriculography (CV). In the volunteer group, the normal values for LVEF, EDV and ESV measured with DGT were found to be 63%+10%, 91 ml + 6 ml and 30 ml + 6ml and r value for the LVEF=0.91 compared with MUGA. In the IHD group, r values compared with CV were 0.915 and 0.97 for the EDV and ESV and 0.934 for the LVEF. Compared with the MUGA, the r value for LVEF was 0.883. In the VHD group, r values were 0.98 for both the EDV and ESV and 0.948 for the LVEF (P<0.002) compared with CV and 0.789 for the LVEF compared with the MUGA. We feel that DGT is an accurate and reproducible technique for LV function measurements.
FRACTIONS: CONCEPTUAL AND DIDACTIC ASPECTS
Directory of Open Access Journals (Sweden)
Sead Rešić
2016-09-01
Full Text Available Fractions represent the manner of writing parts of whole numbers (integers. Rules for operations with fractions differ from rules for operations with integers. Students face difficulties in understanding fractions, especially operations with fractions. These difficulties are well known in didactics of Mathematics throughout the world and there is a lot of research regarding problems in learning about fractions. Methods for facilitating understanding fractions have been discovered, which are essentially related to visualizing operations with fractions.
Slimming and regularization of cozero maps
Directory of Open Access Journals (Sweden)
Mohamad Mehdi Ebrahimi
2017-01-01
Full Text Available Cozero maps are generalized forms of cozero elements. Two particular cases of cozero maps, slim and regular cozero maps, are significant. In this paper we present methods to construct slim and regular cozero maps from a given cozero map. The construction of the slim and the regular cozero map from a cozero map are called slimming and regularization of the cozero map, respectively. Also, we prove that the slimming and regularization create reflector functors, and so we may say that they are the best method of constructing slim and regular cozero maps, in the sense of category theory. Finally, we give slim regularization for a cozero map c:M→L in the general case where A is not a Q-algebra. We use the ring and module of fractions, in this construction process.
Goodrich, Christopher
2015-01-01
This text provides the first comprehensive treatment of the discrete fractional calculus. Experienced researchers will find the text useful as a reference for discrete fractional calculus and topics of current interest. Students who are interested in learning about discrete fractional calculus will find this text to provide a useful starting point. Several exercises are offered at the end of each chapter and select answers have been provided at the end of the book. The presentation of the content is designed to give ample flexibility for potential use in a myriad of courses and for independent study. The novel approach taken by the authors includes a simultaneous treatment of the fractional- and integer-order difference calculus (on a variety of time scales, including both the usual forward and backwards difference operators). The reader will acquire a solid foundation in the classical topics of the discrete calculus while being introduced to exciting recent developments, bringing them to the frontiers of the...
Laskin, Nick
2000-12-01
A new extension of a fractality concept in financial mathematics has been developed. We have introduced a new fractional Langevin-type stochastic differential equation that differs from the standard Langevin equation: (i) by replacing the first-order derivative with respect to time by the fractional derivative of order μ; and (ii) by replacing “white noise” Gaussian stochastic force by the generalized “shot noise”, each pulse of which has a random amplitude with the α-stable Lévy distribution. As an application of the developed fractional non-Gaussian dynamical approach the expression for the probability distribution function (pdf) of the returns has been established. It is shown that the obtained fractional pdf fits well the central part and the tails of the empirical distribution of S&P 500 returns.
Generalized Fractional Statistics
Kaniadakis, G.; A. Lavagno(Politecnico di Torino and INFN Sezione di Torino, Torino Italy); Quarati, P.
1996-01-01
We link, by means of a semiclassical approach, the fractional statistics of particles obeying the Haldane exclusion principle to the Tsallis statistics and derive a generalized quantum entropy and its associated statistics.
Stable Chlorine Isotope Fractionation
Sharp, Z.
2006-12-01
Chlorine isotope partitioning between different phases is not well understood. Pore fluids can have δ37Cl values as low as -8‰, with neoform sediments having strongly positive values. Most strikingly, volcanic gases have δ37Cl values that cover a range in excess of 14‰ (Barnes et al., this meeting). The large range is difficult to explain in terms of equilibrium fractionation, which, although calculated to be very large for Cl in different oxidation states, should be less than 2‰ between chloride species (Schauble et al., 2003, GCA). To address the discrepancy between Nature and theory, we have measured Cl isotope fractionation for selected equilibrium and disequilibrium experiments in order to identify mechanisms that might lead to large fractionations. 1) NaCl (s,l) NaCl (v): NaCl was sealed in an evacuated silica tube and heated at one end, causing vaporization and reprecipitation of NaCl (v) at the cool end of the tube. The fractionation is 0.2‰ at 700°C (halite-vapor) and 0.7‰ at 800°C (liquid-vapor), respectively. The larger fractionation at higher temperature may be related to equilibrium fractionation between liquid and gas vs. `stripping' of the solid in the lower T experiments. 2) Sodalite NaCl(l): Nepheline and excess NaCl were sealed in a Pt crucible at 825°C for 48 hrs producing sodalite. The measured newly-formed sodalite-NaCl fractionation is -0.2‰. 3) Volatilization of HCl: Dry inert gas was bubbled through HCl solutions and the vapor was collected in a downstream water trap. There was no fractionation for 12.4M HCl (HCl fuming) vapor at 25°C. For a 1 M boiling HCl solution, the HCl-vapor fractionation was ~9‰. The difference is probably related to the degree of dissociation in the acid, with HCl dissolved in water for the highly acidic solutions, and dissociated H3O+ and Cl- for lower concentrations. The HCl volatilization experiments are in contrast to earlier vapor-liquid experiments in NaCl-H2O system, where fractionation was
Single fraction stereotactic radiosurgery for multiple brain metastases
Directory of Open Access Journals (Sweden)
Dror Limon, MD
2017-10-01
Conclusion: In single-fraction SRS for patients with multiple BM, smaller total tumor volume, higher total dose, and lower volume of normal brain receiving >12 Gy were associated with increased survival. These data suggest that using SRS for the treatment of multiple BM is efficacious and that outcomes may be affected more by total tumor volume than by the number of lesions.
Liu, Si-Qi; Zhang, Youjin; Zhou, Chunhui
2018-02-01
The generating function of cubic Hodge integrals satisfying the local Calabi-Yau condition is conjectured to be a tau function of a new integrable system which can be regarded as a fractional generalization of the Volterra lattice hierarchy, so we name it the fractional Volterra hierarchy. In this paper, we give the definition of this integrable hierarchy in terms of Lax pair and Hamiltonian formalisms, construct its tau functions, and present its multi-soliton solutions.
fractional differential equations
Indian Academy of Sciences (India)
Pramana – Journal of Physics. Current Issue : Vol. 90, Issue 2 · Current Issue Volume 90 | Issue 2. February 2018. Home · Volumes & Issues · Special Issues · Forthcoming Articles · Search · Editorial Board · Information for Authors · Subscription ...
Spatiotemporal Fractionation Schemes for Irradiating Large Cerebral Arteriovenous Malformations
Energy Technology Data Exchange (ETDEWEB)
Unkelbach, Jan, E-mail: junkelbach@mgh.harvard.edu [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Bussière, Marc R. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Chapman, Paul H. [Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts (United States); Loeffler, Jay S.; Shih, Helen A. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States)
2016-07-01
Purpose: To optimally exploit fractionation effects in the context of radiosurgery treatments of large cerebral arteriovenous malformations (AVMs). In current practice, fractionated treatments divide the dose evenly into several fractions, which generally leads to low obliteration rates. In this work, we investigate the potential benefit of delivering distinct dose distributions in different fractions. Methods and Materials: Five patients with large cerebral AVMs were reviewed and replanned for intensity modulated arc therapy delivered with conventional photon beams. Treatment plans allowing for different dose distributions in all fractions were obtained by performing treatment plan optimization based on the cumulative biologically effective dose delivered at the end of treatment. Results: We show that distinct treatment plans can be designed for different fractions, such that high single-fraction doses are delivered to complementary parts of the AVM. All plans create a similar dose bath in the surrounding normal brain and thereby exploit the fractionation effect. This partial hypofractionation in the AVM along with fractionation in normal brain achieves a net improvement of the therapeutic ratio. We show that a biological dose reduction of approximately 10% in the healthy brain can be achieved compared with reference treatment schedules that deliver the same dose distribution in all fractions. Conclusions: Boosting complementary parts of the target volume in different fractions may provide a therapeutic advantage in fractionated radiosurgery treatments of large cerebral AVMs. The strategy allows for a mean dose reduction in normal brain that may be valuable for a patient population with an otherwise normal life expectancy.
A discrete fractional random transform
Liu, Zhengjun; Zhao, Haifa; Liu, Shutian
2006-01-01
We propose a discrete fractional random transform based on a generalization of the discrete fractional Fourier transform with an intrinsic randomness. Such discrete fractional random transform inheres excellent mathematical properties of the fractional Fourier transform along with some fantastic features of its own. As a primary application, the discrete fractional random transform has been used for image encryption and decryption.
New Fractional Complex Transform for Conformable Fractional Partial Differential Equations
Directory of Open Access Journals (Sweden)
Çenesiz Y.
2016-12-01
Full Text Available Conformable fractional complex transform is introduced in this paper for converting fractional partial differential equations to ordinary differential equations. Hence analytical methods in advanced calculus can be used to solve these equations. Conformable fractional complex transform is implemented to fractional partial differential equations such as space fractional advection diffusion equation and space fractional telegraph equation to obtain the exact solutions of these equations.
Cann, H M
1992-06-01
There are CEPH genetic maps on each homologous human chromosome pair. Genotypes for these maps have been generated in 88 laboratories that receive DNA from a reference panel of large nuclear pedigrees/families supplied by the Centre d'Etude du Polymorphisme Humain. These maps serve as useful tools for the localization of both disease genes and other genes of interest.
Li, Xin; Rooney, William D.; Várallyay, Csanád G.; Gahramanov, Seymur; Muldoon, Leslie L.; Goodman, James A.; Tagge, Ian J.; Selzer, Audrey H.; Pike, Martin M.; Neuwelt, Edward A.; Springer, Charles S.
2010-10-01
The accurate mapping of the tumor blood volume (TBV) fraction ( vb) is a highly desired imaging biometric goal. It is commonly thought that achieving this is difficult, if not impossible, when small molecule contrast reagents (CRs) are used for the T1-weighted (Dynamic-Contrast-Enhanced) DCE-MRI technique. This is because angiogenic malignant tumor vessels allow facile CR extravasation. Here, a three-site equilibrium water exchange model is applied to DCE-MRI data from the cerebrally-implanted rat brain U87 glioma, a tumor exhibiting rapid CR extravasation. Analyses of segments of the (and the entire) DCE data time-course with this "shutter-speed" pharmacokinetic model, which admits finite water exchange kinetics, allow TBV estimation from the first-pass segment. Pairwise parameter determinances were tested with grid searches of 2D parametric error surfaces. Tumor blood volume ( vb), as well as ve (the extracellular, extravascular space volume fraction), and Ktrans (a CR extravasation rate measure) parametric maps are presented. The role of the Patlak Plot in DCE-MRI is also considered.
Jeon, Jae-Hyung; Metzler, Ralf
2010-02-01
Motivated by subdiffusive motion of biomolecules observed in living cells, we study the stochastic properties of a non-Brownian particle whose motion is governed by either fractional Brownian motion or the fractional Langevin equation and restricted to a finite domain. We investigate by analytic calculations and simulations how time-averaged observables (e.g., the time-averaged mean-squared displacement and displacement correlation) are affected by spatial confinement and dimensionality. In particular, we study the degree of weak ergodicity breaking and scatter between different single trajectories for this confined motion in the subdiffusive domain. The general trend is that deviations from ergodicity are decreased with decreasing size of the movement volume and with increasing dimensionality. We define the displacement correlation function and find that this quantity shows distinct features for fractional Brownian motion, fractional Langevin equation, and continuous time subdiffusion, such that it appears an efficient measure to distinguish these different processes based on single-particle trajectory data.
Biswas, Karabi; Caponetto, Riccardo; Mendes Lopes, António; Tenreiro Machado, José António
2017-01-01
This book focuses on two specific areas related to fractional order systems – the realization of physical devices characterized by non-integer order impedance, usually called fractional-order elements (FOEs); and the characterization of vegetable tissues via electrical impedance spectroscopy (EIS) – and provides readers with new tools for designing new types of integrated circuits. The majority of the book addresses FOEs. The interest in these topics is related to the need to produce “analogue” electronic devices characterized by non-integer order impedance, and to the characterization of natural phenomena, which are systems with memory or aftereffects and for which the fractional-order calculus tool is the ideal choice for analysis. FOEs represent the building blocks for designing and realizing analogue integrated electronic circuits, which the authors believe hold the potential for a wealth of mass-market applications. The freedom to choose either an integer- or non-integer-order analogue integrator...
,
2008-01-01
The U.S. Geological Survey (USGS) produced its first topographic map in 1879, the same year it was established. Today, more than 100 years and millions of map copies later, topographic mapping is still a central activity for the USGS. The topographic map remains an indispensable tool for government, science, industry, and leisure. Much has changed since early topographers traveled the unsettled West and carefully plotted the first USGS maps by hand. Advances in survey techniques, instrumentation, and design and printing technologies, as well as the use of aerial photography and satellite data, have dramatically improved mapping coverage, accuracy, and efficiency. Yet cartography, the art and science of mapping, may never before have undergone change more profound than today.
The Local Fractional Bootstrap
DEFF Research Database (Denmark)
Bennedsen, Mikkel; Hounyo, Ulrich; Lunde, Asger
new resampling method, the local fractional bootstrap, relies on simulating an auxiliary fractional Brownian motion that mimics the fine properties of high frequency differences of the Brownian semistationary process under the null hypothesis. We prove the first order validity of the bootstrap method...... and in simulations we observe that the bootstrap-based hypothesis test provides considerable finite-sample improvements over an existing test that is based on a central limit theorem. This is important when studying the roughness properties of time series data; we illustrate this by applying the bootstrap method...
A Computer-Interfaced Drop Counter as an Inexpensive Fraction Collector for Column Chromatography
Nash, Barbara T.
2008-01-01
A computer-interfaced drop counter is described that serves as an inexpensive alternative to a fraction collector for column chromatography experiments. Undergraduate biochemistry laboratories frequently do not have the budget to purchase fraction collectors. Protocols that call for the manual measurement of fraction volumes as well as the manual…
Digestion kinetics of carbohydrate fractions of citrus by-products.
Lashkari, Saman; Taghizadeh, Akbar
2015-01-01
The present experiment was carried out to determine the digestion kinetics of carbohydrate fractions of citrus by-products. Grapefruit pulp (GP), lemon pulp (LE), lime pulp (LI) and orange pulp (OP) were the test feed. Digestion kinetic of whole citrus by-products and neutral detergent fiber (NDF) fraction and acid detergent fiber (ADF) fractions of citrus by-products were measured using the in vitro gas production technique. Fermentation kinetics of the neutral detergent soluble carbohydrates (NDSC) fraction and hemicelluloses were calculated using a curve subtraction. The fermentation rate of whole was the highest for the LE (p citrus by-products lag time was longer for hemicellulose than other carbohydrate fractions. There was no significant difference among potential gas production (A) volumes of whole test feeds (p citrus by-products have high potential for degradability. It could also be concluded that carbohydrate fractions of citrus by-products have remarkable difference in digestion kinetics and digestive behavior.
Brewing with fractionated barley
Donkelaar, van L.H.G.
2016-01-01
Brewing with fractionated barley Beer is a globally consumed beverage, which is produced from malted barley, water, hops and yeast. In recent years, the use of unmalted barley and exogenous enzymes have become more popular because they enable simpler processing and reduced environmental impact. Raw
Fractional Differential Equation
Directory of Open Access Journals (Sweden)
Moustafa El-Shahed
2007-01-01
where 2<α<3 is a real number and D0+α is the standard Riemann-Liouville fractional derivative. Our analysis relies on Krasnoselskiis fixed point theorem of cone preserving operators. An example is also given to illustrate the main results.
Vinogradova, Natalya; Blaine, Larry
2013-01-01
Almost everyone loves chocolate. However, the same cannot be said about fractions, which are loved by markedly fewer. Middle school students tend to view them with wary respect, but little affection. The authors attempt to sweeten the subject by describing a type of game involving division of chocolate bars. The activity they describe provides a…
Energy Technology Data Exchange (ETDEWEB)
Haack, Soeren (Dept. of Clinical Engineering, Aarhus Univ. Hospital (Denmark)), E-mail: Soeren.haack@stab.rm.dk; Morre Pedersen, Erik (Dept. of Radiology, Aarhus Sygehus, Aarhus Univ. Hospital (Denmark)); Jespersen, Sune N. (Center of Functionally Integrative Neuroscience, Aarhus Univ. Hospital (Denmark)); Kallehauge, Jesper F. (Dept. of Medical Physics, Aarhus Univ. Hospital (Denmark)); Lindegaard, Jacob Christian; Tanderup, Kari (Dept. of Oncology Aarhus Univ. Hospital (Denmark))
2010-10-15
Background and purpose. T2 weighted MRI is recommended for image guided adaptive brachytherapy (IGABT) in cervical cancer. Diffusion weighted imaging (DWI) and the derived apparent diffusion coefficient (ADC) may add additional biological information on tumour cell density. The purpose of this study was to evaluate the distribution of the ADC within target volumes as recommended by GEC-ESTRO: Gross Tumour Volume at BT (GTVBT), High-Risk Clinical Tumour Volume (HR-CTV) and Intermediate-Risk Clinical Target Volume (IR-CTV) and to evaluate the change of diffusion between fractions of IGABT. Material and methods. Fifteen patients with locally advanced cervical cancer were examined by MRI before their first (BT1) and second (BT2) fraction of IGABT, resulting in a total of 30 MR examinations including both T2 weighted and DWI sequences. The Apparent Diffusion Coefficient (ADC) was calculated by use of three levels of b-values (0, 600, 1000 s/mm2). ADC maps were constructed and fused with the GEC ESTRO target contours. The mean ADC value within each target volume was calculated. Furthermore, volumes of low diffusion (ADClow) were defined based on an ADC threshold of 1.2 x 10-3 mm2/s, and overlap with target volumes was evaluated. Change of ADC level in target volumes and change of ADClow volume from BT1 to BT2 was also evaluated. Results. The mean ADC was significantly lower in GTVBT than in HR-CTV (p<0.001) which again was significantly lower than in IR-CTV (p<0.001). There was no significant change of the ADClow volume or ADC level within each target structure between BT1 and BT2 (p=0.242). All three GEC-ESTRO volumes contained volumes with low diffusion. The GTVBT contained 37.2% volume of low diffusion, HR-CTV 20.3% and IR-CTV 10.8%. Conclusion. With DWI we were able to find a significant difference in ADC-values for the three different GEC ESTRO targets. This supports the assumption that the target volumes used for dose prescription in IGABT contain tissues with
Haack, Søren; Pedersen, Erik Morre; Jespersen, Sune N; Kallehauge, Jesper F; Lindegaard, Jacob Christian; Tanderup, Kari
2010-10-01
T2 weighted MRI is recommended for image guided adaptive brachytherapy (IGABT) in cervical cancer. Diffusion weighted imaging (DWI) and the derived apparent diffusion coefficient (ADC) may add additional biological information on tumour cell density. The purpose of this study was to evaluate the distribution of the ADC within target volumes as recommended by GEC-ESTRO: Gross Tumour Volume at BT (GTV(BT)), High-Risk Clinical Tumour Volume (HR-CTV) and Intermediate-Risk Clinical Target Volume (IR-CTV) and to evaluate the change of diffusion between fractions of IGABT. Fifteen patients with locally advanced cervical cancer were examined by MRI before their first (BT1) and second (BT2) fraction of IGABT, resulting in a total of 30 MR examinations including both T2 weighted and DWI sequences. The Apparent Diffusion Coefficient (ADC) was calculated by use of three levels of b-values (0, 600, 1000 s/mm(2)). ADC maps were constructed and fused with the GEC ESTRO target contours. The mean ADC value within each target volume was calculated. Furthermore, volumes of low diffusion (ADC(low)) were defined based on an ADC threshold of 1.2 × 10(-3) mm(2)/s, and overlap with target volumes was evaluated. Change of ADC level in target volumes and change of ADC(low) volume from BT1 to BT2 was also evaluated. The mean ADC was significantly lower in GTV(BT) than in HR-CTV (p<0.001) which again was significantly lower than in IR-CTV (p<0.001). There was no significant change of the ADC(low) volume or ADC level within each target structure between BT1 and BT2 (p=0.242). All three GEC-ESTRO volumes contained volumes with low diffusion. The GTV(BT) contained 37.2% volume of low diffusion, HR-CTV 20.3% and IR-CTV 10.8%. With DWI we were able to find a significant difference in ADC-values for the three different GEC ESTRO targets. This supports the assumption that the target volumes used for dose prescription in IGABT contain tissues with different characteristics, with the tumour (GTV
-Dimensional Fractional Lagrange's Inversion Theorem
Directory of Open Access Journals (Sweden)
F. A. Abd El-Salam
2013-01-01
Full Text Available Using Riemann-Liouville fractional differential operator, a fractional extension of the Lagrange inversion theorem and related formulas are developed. The required basic definitions, lemmas, and theorems in the fractional calculus are presented. A fractional form of Lagrange's expansion for one implicitly defined independent variable is obtained. Then, a fractional version of Lagrange's expansion in more than one unknown function is generalized. For extending the treatment in higher dimensions, some relevant vectors and tensors definitions and notations are presented. A fractional Taylor expansion of a function of -dimensional polyadics is derived. A fractional -dimensional Lagrange inversion theorem is proved.
Erratum to: Mapping sediment thickness of Islamabad city using ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Earth System Science; Volume 125; Issue 4. Erratum to: Mapping sediment thickness of Islamabad city using empirical relationships: Implications for seismic hazard assessment. Volume 125 Issue 4 June 2016 pp 897-898 ...
Arbitrage with fractional Gaussian processes
Zhang, Xili; Xiao, Weilin
2017-04-01
While the arbitrage opportunity in the Black-Scholes model driven by fractional Brownian motion has a long history, the arbitrage strategy in the Black-Scholes model driven by general fractional Gaussian processes is in its infancy. The development of stochastic calculus with respect to fractional Gaussian processes allowed us to study such models. In this paper, following the idea of Shiryaev (1998), an arbitrage strategy is constructed for the Black-Scholes model driven by fractional Gaussian processes, when the stochastic integral is interpreted in the Riemann-Stieltjes sense. Arbitrage opportunities in some fractional Gaussian processes, including fractional Brownian motion, sub-fractional Brownian motion, bi-fractional Brownian motion, weighted-fractional Brownian motion and tempered fractional Brownian motion, are also investigated.
Analytic Solutions of the Space-Time Fractional Combined KdV-mKdV Equation
Directory of Open Access Journals (Sweden)
Emad A.-B. Abdel-Salam
2015-01-01
Full Text Available The fractional mapping method is proposed to solve fractional differential equations. To illustrate the effectiveness of the method, we discuss the space-time fractional combined KdV-mKdV equation. Many types of exact analytical solutions are obtained. The solutions include generalized trigonometric and hyperbolic functions solutions. These solutions are useful to understand the mechanisms of the complicated nonlinear physical phenomena and fractional differential equations. Among these solutions, some are found for the first time.
Uranium in US surface, ground, and domestic waters. Volume 2
Energy Technology Data Exchange (ETDEWEB)
Drury, J.S.; Reynolds, S.; Owen, P.T.; Ross, R.H.; Ensminger, J.T.
1981-04-01
The report Uranium in US Surface, Ground, and Domestic Waters comprises four volumes. Volumes 2, 3, and 4 contain data characterizing the location, sampling date, type, use, and uranium conentrations of 89,994 individual samples presented in tabular form. The tabular data in volumes 2, 3, and 4 are summarized in volume 1 in narrative form and with maps and histograms.
Fractional derivatives for physicists and engineers background and theory
Uchaikin, Vladimir V
2013-01-01
The first derivative of a particle coordinate means its velocity, the second means its acceleration, but what does a fractional order derivative mean? Where does it come from, how does it work, where does it lead to? The two-volume book written on high didactic level answers these questions. Fractional Derivatives for Physicists and Engineers— The first volume contains a clear introduction into such a modern branch of analysis as the fractional calculus. The second develops a wide panorama of applications of the fractional calculus to various physical problems. This book recovers new perspectives in front of the reader dealing with turbulence and semiconductors, plasma and thermodynamics, mechanics and quantum optics, nanophysics and astrophysics. The book is addressed to students, engineers and physicists, specialists in theory of probability and statistics, in mathematical modeling and numerical simulations, to everybody who doesn't wish to stay apart from the new mathematical methods becoming more and ...
Deformable structure registration of bladder through surface mapping.
Xiong, Li; Viswanathan, Akila; Stewart, Alexandra J; Haker, Steven; Tempany, Clare M; Chin, Lee M; Cormack, Robert A
2006-06-01
Cumulative dose distributions in fractionated radiation therapy depict the dose to normal tissues and therefore may permit an estimation of the risk of normal tissue complications. However, calculation of these distributions is highly challenging because of interfractional changes in the geometry of patient anatomy. This work presents an algorithm for deformable structure registration of the bladder and the verification of the accuracy of the algorithm using phantom and patient data. In this algorithm, the registration process involves conformal mapping of genus zero surfaces using finite element analysis, and guided by three control landmarks. The registration produces a correspondence between fractions of the triangular meshes used to describe the bladder surface. For validation of the algorithm, two types of balloons were inflated gradually to three times their original size, and several computerized tomography (CT) scans were taken during the process. The registration algorithm yielded a local accuracy of 4 mm along the balloon surface. The algorithm was then applied to CT data of patients receiving fractionated high-dose-rate brachytherapy to the vaginal cuff, with the vaginal cylinder in situ. The patients' bladder filling status was intentionally different for each fraction. The three required control landmark points were identified for the bladder based on anatomy. Out of an Institutional Review Board (IRB) approved study of 20 patients, 3 had radiographically identifiable points near the bladder surface that were used for verification of the accuracy of the registration. The verification point as seen in each fraction was compared with its predicted location based on affine as well as deformable registration. Despite the variation in bladder shape and volume, the deformable registration was accurate to 5 mm, consistently outperforming the affine registration. We conclude that the structure registration algorithm presented works with reasonable accuracy and
Multicomponent diffusivities from the free volume theory
Wesselingh, J.A; Bollen, A.M
In this paper the free volume theory of diffusion is extended to multicomponent mixtures. The free volume is taken to be accessible for any component according to its surface. fraction. The resulting equations predict multicomponent (Maxwell-Stefan) diffusivities in simple liquid mixtures from pure
Fractional cointegration rank estimation
DEFF Research Database (Denmark)
Lasak, Katarzyna; Velasco, Carlos
We consider cointegration rank estimation for a p-dimensional Fractional Vector Error Correction Model. We propose a new two-step procedure which allows testing for further long-run equilibrium relations with possibly different persistence levels. The fi…rst step consists in estimating the parame......We consider cointegration rank estimation for a p-dimensional Fractional Vector Error Correction Model. We propose a new two-step procedure which allows testing for further long-run equilibrium relations with possibly different persistence levels. The fi…rst step consists in estimating...... to control for stochastic trend estimation effects from the first step. The critical values of the tests proposed depend only on the number of common trends under the null, p - r, and on the interval of the cointegration degrees b allowed, but not on the true cointegration degree b0. Hence, no additional...
Alternatives for plasma fractionation.
Schneider, W; Wolter, D; McCarty, L J
1976-01-01
At the present time there is an enormously increasing demand for albumin. The most common procedure for the isolation of this plasma component is the cold ethanol technique developed by Cohn. Because this process necessarily isolates other blood components for which there is less demand in relation to albumin, albumin production is expensive. Therefore, we have developed a two-step fractionation for the isolation of albumin. It is basically a heat precipitation method with the albumin yield being about 90% of the original plasma albumin. In comparison to cold ethanol methods, it is considerably less expensive. Other blood components, e.g., clotting factors, immunoglobulins, may also be isolated. A nonmodified gamma-globulin for intravenous use is obtained by removing anti-complementary activity with hydroxyethyl starch. Additional fractionation steps are required to isolate these other components, but unlike in established methods, these are not necessary for the isolation of solely albumin.
Fractional Galilean symmetries
Directory of Open Access Journals (Sweden)
Ali Hosseiny
2016-09-01
Full Text Available We generalize the differential representation of the operators of the Galilean algebras to include fractional derivatives. As a result a whole new class of scale invariant Galilean algebras are obtained. The first member of this class has dynamical index z=2 similar to the Schrödinger algebra. The second member of the class has dynamical index z=3/2, which happens to be the dynamical index Kardar–Parisi–Zhang equation.
Fractional Number Operator and Associated Fractional Diffusion Equations
Rguigui, Hafedh
2018-03-01
In this paper, we study the fractional number operator as an analog of the finite-dimensional fractional Laplacian. An important relation with the Ornstein-Uhlenbeck process is given. Using a semigroup approach, the solution of the Cauchy problem associated to the fractional number operator is presented. By means of the Mittag-Leffler function and the Laplace transform, we give the solution of the Caputo time fractional diffusion equation and Riemann-Liouville time fractional diffusion equation in infinite dimensions associated to the fractional number operator.
Khonina, S N; Ustinov, A V
2017-11-01
Airy beams possess a number of properties that ensure their multifunction and high relevance in many applications. This fact stimulates scientists to search for new modifications and generalizations of classical Airy beams. Several generalizations of the Airy functions are known, on the basis of both the modification of the differential equation and the variations in the integral representation. In this paper we propose and investigate a new type of Airy beams-fractional Airy beams (FrAiB). They are based on the generalization of the integral representation and are close to the Olver functions, but we are considering a wider range of the power-law dependence of the argument, including non-integer (fractional) values of the power. A theoretical and numerical analysis of the FrAiBs, as well as their symmetrized variants, was performed. The properties of FrAiBs, such as being non-diffracting and autofocusing, were numerically investigated by means of the fractional Fourier transform, describing the beam transformations by paraxial optical systems. We believe that new beams can be useful for laser manipulation techniques and lensless laser patterning.
A feasible and automatic free tool for T1 and ECV mapping.
Altabella, Luisa; Borrazzo, Cristian; Carnì, Marco; Galea, Nicola; Francone, Marco; Fiorelli, Andrea; Di Castro, Elisabetta; Catalano, Carlo; Carbone, Iacopo
2017-01-01
Cardiac magnetic resonance (CMR) is a useful non-invasive tool for characterizing tissues and detecting myocardial fibrosis and edema. Estimation of extracellular volume fraction (ECV) using T1 sequences is emerging as an accurate biomarker in cardiac diseases associated with diffuse fibrosis. In this study, automatic software for T1 and ECV map generation consisting of an executable file was developed and validated using phantom and human data. T1 mapping was performed in phantoms and 30 subjects (22 patients and 8 healthy subjects) on a 1.5T MR scanner using the modified Look-Locker inversion-recovery (MOLLI) sequence prototype before and 15 min after contrast agent administration. T1 maps were generated using a Fast Nonlinear Least Squares algorithm. Myocardial ECV maps were generated using both pre- and post-contrast T1 image registration and automatic extraction of blood relaxation rates. Using our software, pre- and post-contrast T1 maps were obtained in phantoms and healthy subjects resulting in a robust and reliable quantification as compared to reference software. Coregistration of pre- and post-contrast images improved the quality of ECV maps. Mean ECV value in healthy subjects was 24.5%±2.5%. This study demonstrated that it is possible to obtain accurate T1 maps and informative ECV maps using our software. Pixel-wise ECV maps obtained with this automatic software made it possible to visualize and evaluate the extent and severity of ECV alterations. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
Martin, Josh
2012-01-01
After accepting the principal position at Farmersville (TX) Junior High, the author decided to increase instructional rigor through question mapping because of the success he saw using this instructional practice at his prior campus. Teachers are the number one influence on student achievement (Marzano, 2003), so question mapping provides a…
DEFF Research Database (Denmark)
Rasmussen, Lauge Baungaard
2006-01-01
The lecture note explains how to use the causal mapping method as well as the theoretical framework aoosciated to the method......The lecture note explains how to use the causal mapping method as well as the theoretical framework aoosciated to the method...
High Volume Fraction Carbon Nanotube Composites for Aerospace Applications
Siochi, E. J.; Kim, J.-W.; Sauti, G.; Cano, R. J.; Wincheski, R. A.; Ratcliffe, J. G.; Czabaj, M.
2016-01-01
Reported mechanical properties of carbon nanotubes (CNTs) at the nanoscale suggest their potential to enable significantly lighter structures of interest for space applications. However, their utility depends on the retention of these properties in bulk material formats that permit practical fabrication of large structures. This presentation summarizes recent progress made to produce carbon nanotube composites with specific tensile properties that begin to rival those of carbon fiber reinforced polymer composites. CNT content in these nanocomposites was greater than 70% by weight. Tested nanocomposite specimens were fabricated from kilometers or tens of square meters of CNT, depending on the starting material format. Processing methods to yield these results, and characterization and testing to evaluate the performance of these composites will be discussed. The final objective is the demonstration of a CNT composite overwrapped pressure vessel to be flight tested in the Fall of 2016.
Tcp and NTCP radiobiological models: conventional and hypo fractionated treatments in radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Astudillo V, A.; Paredes G, L. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Resendiz G, G.; Posadas V, A. [Hospital Angeles Lomas, Av. Vialidad de la Barranca s/n, Col. Valle de las Palmas, 52763 Huixquilucan de Degallado, Estado de Mexico (Mexico); Mitsoura, E. [Universidad Autonoma del Estado de Mexico, Facultad de Medicina, Paseo Tollocan, Esq. Jesus Carranza s/n, Col. Moderna de la Cruz, 50180 Toluca, Estado de Mexico (Mexico); Rodriguez L, A.; Flores C, J. M., E-mail: armando.astudillo@inin.gob.mx [Hospital Medica Sur, Puente de Piedra 150, Col. Toriello Guerra, 14050 Tlalpan, Mexico D. F. (Mexico)
2015-10-15
The hypo and conventional fractionated schedules performance were compared in terms of the tumor control and the normal tissue complications. From the records of ten patients, treated for adenocarcinoma and without mastectomy, the dose-volume histogram was used. Using radiobiological models the probabilities for tumor control and normal tissue complications were calculated. For both schedules the tumor control was approximately the same. However, the damage in the normal tissue was larger in conventional fractionated schedule. This is important because patients assistance time to their fractions (15 fractions/25 fractions) can be optimized. Thus, the hypo fractionated schedule has suitable characteristics to be implemented. (Author)
Stemkens, Bjorn; Glitzner, Markus; Kontaxis, Charis; de Senneville, Baudouin Denis; Prins, Fieke M.; Crijns, Sjoerd P. M.; Kerkmeijer, Linda G. W.; Lagendijk, Jan J. W.; van den Berg, Cornelis A. T.; Tijssen, Rob H. N.
2017-09-01
Stereotactic body radiation therapy (SBRT) has shown great promise in increasing local control rates for renal-cell carcinoma (RCC). Characterized by steep dose gradients and high fraction doses, these hypo-fractionated treatments are, however, prone to dosimetric errors as a result of variations in intra-fraction respiratory-induced motion, such as drifts and amplitude alterations. This may lead to significant variations in the deposited dose. This study aims to develop a method for calculating the accumulated dose for MRI-guided SBRT of RCC in the presence of intra-fraction respiratory variations and determine the effect of such variations on the deposited dose. For this, RCC SBRT treatments were simulated while the underlying anatomy was moving, based on motion information from three motion models with increasing complexity: (1) STATIC, in which static anatomy was assumed, (2) AVG-RESP, in which 4D-MRI phase-volumes were time-weighted, and (3) PCA, a method that generates 3D volumes with sufficient spatio-temporal resolution to capture respiration and intra-fraction variations. Five RCC patients and two volunteers were included and treatments delivery was simulated, using motion derived from subject-specific MR imaging. Motion was most accurately estimated using the PCA method with root-mean-squared errors of 2.7, 2.4, 1.0 mm for STATIC, AVG-RESP and PCA, respectively. The heterogeneous patient group demonstrated relatively large dosimetric differences between the STATIC and AVG-RESP, and the PCA reconstructed dose maps, with hotspots up to 40% of the D99 and an underdosed GTV in three out of the five patients. This shows the potential importance of including intra-fraction motion variations in dose calculations.
The Extended Fractional Subequation Method for Nonlinear Fractional Differential Equations
Zhao, Jianping; Tang, Bo; Kumar, Sunil; Hou, Yanren
2012-01-01
An extended fractional subequation method is proposed for solving fractional differential equations by introducing a new general ansätz and Bäcklund transformation of the fractional Riccati equation with known solutions. Being concise and straightforward, this method is applied to the space-time fractional coupled Burgers’ equations and coupled MKdV equations. As a result, many exact solutions are obtained. It is shown that the considered method provides a very effective, convenient, and powe...
Fractional Langevin equation and Riemann-Liouville fractional derivative.
Sau Fa, Kwok
2007-10-01
In this present work we consider a fractional Langevin equation with Riemann-Liouville fractional time derivative which modifies the classical Newtonian force, nonlocal dissipative force, and long-time correlation. We investigate the first two moments, variances and position and velocity correlation functions of this system. We also compare them with the results obtained from the same fractional Langevin equation which uses the Caputo fractional derivative.
Methane productivity of manure, straw and solid fractions of manure
DEFF Research Database (Denmark)
Møller, H.B.; Sommer, S.G.; Ahring, Birgitte Kiær
2004-01-01
are in the same range (282-301 m(3) CH4 LU-1). Pre-treatment of manure by separation is a way of making fractions of the manure that have a higher gas potential per volume. Theoretical methane potential and biodegradability of three types of fractions deriving from manure separation were tested. The volumetric...... methane yield of straw was found to be higher than the yield from total manure and the solid fractions of manure, due to the higher VS content, and hence the use of straw as bedding material will increase the volumetric as well as the livestock-based methane productivity....
Two-Dimensional Fractional Order Generalized Thermoelastic Porous Material
Directory of Open Access Journals (Sweden)
Ibrahim A. Abbas
Full Text Available AbstractIn the work, a two-dimensional problem of a porous material is considered within the context of the fractional order generalized thermoelasticity theory with one relaxation time. The medium is assumed initially quiescent for a thermoelastic half space whose surface is traction free and has a constant heat flux. The normal mode analysis and eigenvalue approach techniques are used to solve the resulting non-dimensional coupled equations. The effect of the fractional order of the temperature, displacement components, the stress components, changes in volume fraction field and temperature distribution have been depicted graphically.
Cosmological Models with Fractional Derivatives and Fractional Action Functional
Shchigolev, V. K.
2010-01-01
Cosmological models of a scalar field with dynamical equations containing fractional derivatives or derived from the Einstein-Hilbert action of fractional order, are constructed. A number of exact solutions to those equations of fractional cosmological models in both cases is given.
Multigrid, Fractional-Step Computation Of Flow
Kwak, Dochan; Rosenfeld, Moshe
1996-01-01
Speed of computer code solving three-dimensional Navier-Stokes equations of flow of incompressible fluid by fractional-step method increased significantly by use of multigrid procedures. In method, equations solved on general nonorthogonal curvilinear coordinate grid, using volume fluxes. At each time step, computations performed in two fractional steps. In first step, equations of conservation of momentum solved by use of gradient of pressure from previous time step via explicit approximate-factorization method, yielding approximate flow field that does not satisfy equation of conservation of mass. In second step, discrete Poisson-like equation with Neumann-type boundary conditions, formed by combining equations of conservation of momentum and mass, solved iteratively.
DEFF Research Database (Denmark)
Salovaara-Moring, Inka
2016-01-01
practice. In particular, mapping environmental damage, endangered species, and human-made disasters has become one focal point for environmental knowledge production. This type of digital map has been highlighted as a processual turn in critical cartography, whereas in related computational journalism......, it can be seen as an interactive and iterative process of mapping complex and fragile ecological developments. This article looks at computer-assisted cartography as part of environmental knowledge production. It uses InfoAmazonia, the data-journalism platform on Amazon rainforests, as an example...
A functional equation for the Riemann Zeta fractional derivative
Guariglia, Emanuel; Silvestrov, Sergei
2017-01-01
In this paper a functional equation for the fractional derivative of the Riemann ζ function is presented. The fractional derivative of ζ is computed by a generalization of the Grünwald-Letnikov fractional operator, which satisfies the generalized Leibniz rule. It is applied to the asymmetric functional equation of ζ in order to obtain the result sought. Moreover, further properties of this fractional derivative are proposed and discussed. At the request of both authors and with the approval of the proceedings editor, article 020146 titled, "A functional equation for the Riemann Zeta fractional derivative," is being retracted from the public record due to the fact that it is a duplication of article 020063 published in the same volume.
Unbiased estimation of cell number using the automatic optical fractionator.
Mouton, Peter R; Phoulady, Hady Ahmady; Goldgof, Dmitry; Hall, Lawrence O; Gordon, Marcia; Morgan, David
2017-03-01
A novel stereology approach, the automatic optical fractionator, is presented for obtaining unbiased and efficient estimates of the number of cells in tissue sections. Used in combination with existing segmentation algorithms and ordinary immunostaining methods, automatic estimates of cell number are obtainable from extended depth of field images built from three-dimensional volumes of tissue (disector stacks). The automatic optical fractionator is more accurate, 100% objective and 8-10 times faster than the manual optical fractionator. An example of the automatic fractionator is provided for counts of immunostained neurons in neocortex of a genetically modified mouse model of neurodegeneration. Evidence is presented for the often overlooked prerequisite that accurate counting by the optical fractionator requires a thin focal plane generated by a high optical resolution lens. Copyright © 2016 Elsevier B.V. All rights reserved.
Fleming, John; Conway, Joy; Majoral, Caroline; Bennett, Michael; Caillibotte, Georges; Montesantos, Spyridon; Katz, Ira
2014-02-01
Determination of the lung outline and regional lung air volume is of value in analysis of three-dimensional (3D) distribution of aerosol deposition from radionuclide imaging. This study describes a technique for using computed tomography (CT) scans for this purpose. Low-resolution CT scans of the thorax were obtained during tidal breathing in 11 healthy control male subjects on two occasions. The 3D outline of the lung was determined by image processing using minimal user interaction. A 3D map of air volume was derived and total lung air volume calculated. The regional distribution of air volume from center to periphery of the lung was analyzed using a radial transform and the outer-to-inner ratio of air volume determined. The average total air volume in the lung was 1,900±126 mL (1 SEM), which is in general agreement with the expected value for adult male subjects in the supine position. The fractional air volume concentration increased from the center toward the periphery of the lung. Outer-to-inner (O/I) ratios were higher for the left lung [11.5±1.8 (1 SD)] than for the right [10.1±0.8 (1 SD)] (plungs from CT images and obtaining an image of the distribution of air volume is described. The normal range of various parameters describing the regional distribution of air volume is presented, together with a measure of intrasubject repeatability. This technique and data will be of value in analyzing 3D radionuclide images of aerosol deposition.
Myocardial T1 and T2 Mapping: Techniques and Clinical Applications.
Kim, Pan Ki; Hong, Yoo Jin; Im, Dong Jin; Suh, Young Joo; Park, Chul Hwan; Kim, Jin Young; Chang, Suyon; Lee, Hye-Jeong; Hur, Jin; Kim, Young Jin; Choi, Byoung Wook
2017-01-01
Cardiac magnetic resonance (CMR) imaging is widely used in various medical fields related to cardiovascular diseases. Rapid technological innovations in magnetic resonance imaging in recent times have resulted in the development of new techniques for CMR imaging. T1 and T2 image mapping sequences enable the direct quantification of T1, T2, and extracellular volume fraction (ECV) values of the myocardium, leading to the progressive integration of these sequences into routine CMR settings. Currently, T1, T2, and ECV values are being recognized as not only robust biomarkers for diagnosis of cardiomyopathies, but also predictive factors for treatment monitoring and prognosis. In this study, we have reviewed various T1 and T2 mapping sequence techniques and their clinical applications.
Myocardial T1 and T2 mapping: Techniques and clinical applications
Energy Technology Data Exchange (ETDEWEB)
Kim, Pan Ki; Hong, Yoo Jin; Im, Dong Jin [Dept. of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); and others
2017-01-15
Cardiac magnetic resonance (CMR) imaging is widely used in various medical fields related to cardiovascular diseases. Rapid technological innovations in magnetic resonance imaging in recent times have resulted in the development of new techniques for CMR imaging. T1 and T2 image mapping sequences enable the direct quantification of T1, T2, and extracellular volume fraction (ECV) values of the myocardium, leading to the progressive integration of these sequences into routine CMR settings. Currently, T1, T2, and ECV values are being recognized as not only robust biomarkers for diagnosis of cardiomyopathies, but also predictive factors for treatment monitoring and prognosis. In this study, we have reviewed various T1 and T2 mapping sequence techniques and their clinical applications.
Advances in robust fractional control
Padula, Fabrizio
2015-01-01
This monograph presents design methodologies for (robust) fractional control systems. It shows the reader how to take advantage of the superior flexibility of fractional control systems compared with integer-order systems in achieving more challenging control requirements. There is a high degree of current interest in fractional systems and fractional control arising from both academia and industry and readers from both milieux are catered to in the text. Different design approaches having in common a trade-off between robustness and performance of the control system are considered explicitly. The text generalizes methodologies, techniques and theoretical results that have been successfully applied in classical (integer) control to the fractional case. The first part of Advances in Robust Fractional Control is the more industrially-oriented. It focuses on the design of fractional controllers for integer processes. In particular, it considers fractional-order proportional-integral-derivative controllers, becau...
Fractional variational principles with delay
Baleanu, Dumitru; Maaraba Abdeljawad, Thabet; Jarad, Fahd
2008-08-01
The fractional variational principles within Riemann-Liouville fractional derivatives in the presence of delay are analyzed. The corresponding Euler-Lagrange equations are obtained and one example is analyzed in detail.
Fractional variational principles with delay
Energy Technology Data Exchange (ETDEWEB)
Baleanu, Dumitru; Abdeljawad, Thabet Maaraba; Jarad, Fahd [Department of Mathematics and Computer Sciences, Faculty of Arts and Sciences, Cankaya University, 06530 Ankara (Turkey)], E-mail: dumitru@cankaya.edu.tr, E-mail: baleanu@venus.nipne.ro
2008-08-08
The fractional variational principles within Riemann-Liouville fractional derivatives in the presence of delay are analyzed. The corresponding Euler-Lagrange equations are obtained and one example is analyzed in detail.
Existence of solutions for fractional differential inclusions with boundary conditions
Directory of Open Access Journals (Sweden)
Dandan Yang
2010-07-01
Full Text Available This article concerns the existence of solutions for fractional-order differential inclusions with boundary-value conditions. The main tools are based on fixed point theorems due to Bohnerblust-Karlin and Leray-Schauder together with a continuous selection theorem for upper semi-continuous multi-valued maps.
A COURSE IN URDU, VOLUME THREE.
BARKER, MUHAMMAD ABD AL RAHMAN; AND OTHERS
THIS SUPPLEMENTARY VOLUME OF "A COURSE IN URDU" CONSISTS OF FIVE APPENDICES--(1) ABBREVIATIONS, (2) URDU-ENGLISH VOCABULARY, (3) ENGLISH-URDU FINDER LIST, (4) SUPPLEMENTARY URDU-ENGLISH VOCABULARY, AND (5) ENGLISH-URDU FINDER LIST FOR THE SUPPLEMENTARY VOCABULARY. ALSO INCLUDED IS AN INDEX TO ALL VOLUMES AND A LANGUAGE MAP OF INDIA AND…
How Weird Are Weird Fractions?
Stuffelbeam, Ryan
2013-01-01
A positive rational is a weird fraction if its value is unchanged by an illegitimate, digit-based reduction. In this article, we prove that each weird fraction is uniquely weird and initiate a discussion of the prevalence of weird fractions.
Fractional Hopfield Neural Networks: Fractional Dynamic Associative Recurrent Neural Networks.
Pu, Yi-Fei; Yi, Zhang; Zhou, Ji-Liu
2017-10-01
This paper mainly discusses a novel conceptual framework: fractional Hopfield neural networks (FHNN). As is commonly known, fractional calculus has been incorporated into artificial neural networks, mainly because of its long-term memory and nonlocality. Some researchers have made interesting attempts at fractional neural networks and gained competitive advantages over integer-order neural networks. Therefore, it is naturally makes one ponder how to generalize the first-order Hopfield neural networks to the fractional-order ones, and how to implement FHNN by means of fractional calculus. We propose to introduce a novel mathematical method: fractional calculus to implement FHNN. First, we implement fractor in the form of an analog circuit. Second, we implement FHNN by utilizing fractor and the fractional steepest descent approach, construct its Lyapunov function, and further analyze its attractors. Third, we perform experiments to analyze the stability and convergence of FHNN, and further discuss its applications to the defense against chip cloning attacks for anticounterfeiting. The main contribution of our work is to propose FHNN in the form of an analog circuit by utilizing a fractor and the fractional steepest descent approach, construct its Lyapunov function, prove its Lyapunov stability, analyze its attractors, and apply FHNN to the defense against chip cloning attacks for anticounterfeiting. A significant advantage of FHNN is that its attractors essentially relate to the neuron's fractional order. FHNN possesses the fractional-order-stability and fractional-order-sensitivity characteristics.
Kosambi and the Genetic Mapping Function
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 6. Kosambi and the Genetic Mapping Function. K K Vinod. General Article Volume 16 Issue 6 June 2011 pp 540-550. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/016/06/0540-0550. Keywords.
Pen, Ue-Li; Staveley-Smith, Lister; Chang, Tzu-Ching; Peterson, Jeff; Bandura, Kevin
2008-04-01
We propose to scan the 2dF survey field with Parkes multibeam in driftscan mode to make a map to cross correlate with galaxy redshifts. This allows a statistical detection of HI large scale structure out to z=0.15. In this cross correlation, the HI in ALL galaxies contributes, not only the bright ones, which significantly boosts the sensitivity. The proposed 40 hours on the fields result in a forecasted 20 sigma detection. The survey volume is 10 million cubic megaparsec, which contain 10^15 solar masses of hydrogen.
Radiation dose-volume effects in the lung
DEFF Research Database (Denmark)
Marks, Lawrence B; Bentzen, Soren M; Deasy, Joseph O
2010-01-01
The three-dimensional dose, volume, and outcome data for lung are reviewed in detail. The rate of symptomatic pneumonitis is related to many dosimetric parameters, and there are no evident threshold "tolerance dose-volume" levels. There are strong volume and fractionation effects....
Membrane Assisted Enzyme Fractionation
DEFF Research Database (Denmark)
Yuan, Linfeng
Purification of proteins is an increasingly important process for the biotechnology industry. Separation of the desired high value protein from other proteins produced by the cell is usually attempted using a combination of different chromatographic techniques. These techniques separate mixtures...... of proteins on the basis of their charge, degree of hydrophobicity, affinity or size. Adequate purity is often not achieved unless several purification steps are combined thereby increasing cost and reducing product yield. Conventional fractionation of proteins using ultrafiltration membranes is limited....... In this thesis, separations using crossflow elecro-membrane filtration (EMF) of amino acids, bovine serum albumin (BSA) and industrial enzymes from Novozymes were performed. The main objective of this study was to investigate the technological feasibility of EMF in the application of industrial enzyme...
Energy Technology Data Exchange (ETDEWEB)
Vernardos, G.; Fluke, C. J.; Croton, D. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria, 3122 (Australia); Bate, N. F. [Sydney Institute for Astronomy, School of Physics, A28, University of Sydney, NSW, 2006 (Australia)
2014-03-01
As synoptic all-sky surveys begin to discover new multiply lensed quasars, the flow of data will enable statistical cosmological microlensing studies of sufficient size to constrain quasar accretion disk and supermassive black hole properties. In preparation for this new era, we are undertaking the GPU-Enabled, High Resolution cosmological MicroLensing parameter survey (GERLUMPH). We present here the GERLUMPH Data Release 1, which consists of 12,342 high resolution cosmological microlensing magnification maps and provides the first uniform coverage of the convergence, shear, and smooth matter fraction parameter space. We use these maps to perform a comprehensive numerical investigation of the mass-sheet degeneracy, finding excellent agreement with its predictions. We study the effect of smooth matter on microlensing induced magnification fluctuations. In particular, in the minima and saddle-point regions, fluctuations are enhanced only along the critical line, while in the maxima region they are always enhanced for high smooth matter fractions (≈0.9). We describe our approach to data management, including the use of an SQL database with a Web interface for data access and online analysis, obviating the need for individuals to download large volumes of data. In combination with existing observational databases and online applications, the GERLUMPH archive represents a fundamental component of a new microlensing eResearch cloud. Our maps and tools are publicly available at http://gerlumph.swin.edu.au/.
Toward lattice fractional vector calculus
Tarasov, Vasily E.
2014-09-01
An analog of fractional vector calculus for physical lattice models is suggested. We use an approach based on the models of three-dimensional lattices with long-range inter-particle interactions. The lattice analogs of fractional partial derivatives are represented by kernels of lattice long-range interactions, where the Fourier series transformations of these kernels have a power-law form with respect to wave vector components. In the continuum limit, these lattice partial derivatives give derivatives of non-integer order with respect to coordinates. In the three-dimensional description of the non-local continuum, the fractional differential operators have the form of fractional partial derivatives of the Riesz type. As examples of the applications of the suggested lattice fractional vector calculus, we give lattice models with long-range interactions for the fractional Maxwell equations of non-local continuous media and for the fractional generalization of the Mindlin and Aifantis continuum models of gradient elasticity.
Capacitive Sensing Of Gaseous Fraction In Two-Phase Flow
Crowley, Christopher J.; Sahm, Michael K.
1995-01-01
Instrument makes nonintrusive, real-time capacitive measurements to determine volume fraction of vapor or other gas in flowing, electrically nonconductive liquid/gas mixture. Works even with liquids having relatively low permittivities. Useful for measuring proportions of vapor in boiling, condensing, and flowing heat-transfer fluids and in cryogenic fluids.
Fractional vector calculus and fractional Maxwell’s equations
Tarasov, Vasily E.
2008-11-01
The theory of derivatives and integrals of non-integer order goes back to Leibniz, Liouville, Grunwald, Letnikov and Riemann. The history of fractional vector calculus (FVC) has only 10 years. The main approaches to formulate a FVC, which are used in the physics during the past few years, will be briefly described in this paper. We solve some problems of consistent formulations of FVC by using a fractional generalization of the Fundamental Theorem of Calculus. We define the differential and integral vector operations. The fractional Green's, Stokes' and Gauss's theorems are formulated. The proofs of these theorems are realized for simplest regions. A fractional generalization of exterior differential calculus of differential forms is discussed. Fractional nonlocal Maxwell's equations and the corresponding fractional wave equations are considered.
DEFF Research Database (Denmark)
Collin, Ib; Nielsen, Povl Holm; Larsen, Michael Holm
1998-01-01
To enhance the industrial applications of CALS, CALS Center Danmark has developed a cost efficient and transparent assessment, CALS Mapping, to uncover the potential of CALS - primarily dedicated to small and medium sized enterprises. The idea behind CALS Mapping is that the CALS State...... of the enterprise is compared with a Reference Enterprise Model (REM). The REM is a CALS idealised enterprise providing full product support throughout the extended enterprise and containing different manufacturing aspects, e.g. component industry, process industry, and one-piece production. This CALS idealised...... enterprise is, when applied in a given organisation modified with respect to the industry regarded, hence irrelevant measure parameters are eliminated to avoid redundancy. This assessment of CALS Mapping, quantify the CALS potential of an organisation with the purpose of providing decision support to the top...
Continuous and discrete fractional operators and some fractional functions
Sadjang, P. Njionou; Mboutngam, S.
2016-01-01
The classical orthogonal polynomials are usually defined by the Rodrigues' formula. This paper refers to a fractional extension of the classical Hermite, Laguerre, Jacobi, Charlier, Meixner, Krawtchouk and Hahn polynomials. By means of the Caputo operator of fractional calculus, C-Hermite, C-Laguerre, C-Legndre and the C-Jacobi functions are defined and their representation in terms of the hypergeometric functions are provided. Also, by means of the Gray and Zhang fractional difference oparat...
Fractional telegrapher's equation from fractional persistent random walks
Masoliver, Jaume, 1951-
2016-01-01
We generalize the telegrapher's equation to allow for anomalous transport. We derive the space-time fractional telegrapher's equation using the formalism of the persistent random walk in continuous time. We also obtain the characteristic function of the space-time fractional process and study some particular cases and asymptotic approximations. Similarly to the ordinary telegrapher's equation, the time-fractional equation also presents distinct behaviors for different time scales. Specificall...
DEFF Research Database (Denmark)
Minder, Bettina; Laursen, Linda Nhu; Lassen, Astrid Heidemann
2014-01-01
. Conceptual clustering is used to analyse and order information according to concepts or variables from within the data. The cognitive maps identified are validated through the comments of some of the same experts. The study presents three cognitive maps and respective world-views explaining how the design...... and innovation field are related and under which dimensions they differ. The paper draws preliminary conclusions on the implications of the different world- views on the innovation process. With the growing importance of the design approach in innovation e.g. design thinking, a clear conception...
DEFF Research Database (Denmark)
Salovaara-Moring, Inka
towards a new political ecology. This type of digital cartographies has been highlighted as the ‘processual turn’ in critical cartography, whereas in related computational journalism it can be seen as an interactive and iterative process of mapping complex and fragile ecological developments. This paper...... looks at computer-assisted cartography as part of environmental knowledge production. It uses InfoAmazonia, the databased platform on Amazon rainforests, as an example of affective geo-visualization within information mapping that enhances embodiment in the experience of the information. Amazonia...
Fractional telegrapher's equation from fractional persistent random walks.
Masoliver, Jaume
2016-05-01
We generalize the telegrapher's equation to allow for anomalous transport. We derive the space-time fractional telegrapher's equation using the formalism of the persistent random walk in continuous time. We also obtain the characteristic function of the space-time fractional process and study some particular cases and asymptotic approximations. Similarly to the ordinary telegrapher's equation, the time-fractional equation also presents distinct behaviors for different time scales. Specifically, transitions between different subdiffusive regimes or from superdiffusion to subdiffusion are shown by the fractional equation as time progresses.
Fractional telegrapher's equation from fractional persistent random walks
Masoliver, Jaume
2016-05-01
We generalize the telegrapher's equation to allow for anomalous transport. We derive the space-time fractional telegrapher's equation using the formalism of the persistent random walk in continuous time. We also obtain the characteristic function of the space-time fractional process and study some particular cases and asymptotic approximations. Similarly to the ordinary telegrapher's equation, the time-fractional equation also presents distinct behaviors for different time scales. Specifically, transitions between different subdiffusive regimes or from superdiffusion to subdiffusion are shown by the fractional equation as time progresses.
Polder maps: improving OMIT maps by excluding bulk solvent.
Liebschner, Dorothee; Afonine, Pavel V; Moriarty, Nigel W; Poon, Billy K; Sobolev, Oleg V; Terwilliger, Thomas C; Adams, Paul D
2017-02-01
The crystallographic maps that are routinely used during the structure-solution workflow are almost always model-biased because model information is used for their calculation. As these maps are also used to validate the atomic models that result from model building and refinement, this constitutes an immediate problem: anything added to the model will manifest itself in the map and thus hinder the validation. OMIT maps are a common tool to verify the presence of atoms in the model. The simplest way to compute an OMIT map is to exclude the atoms in question from the structure, update the corresponding structure factors and compute a residual map. It is then expected that if these atoms are present in the crystal structure, the electron density for the omitted atoms will be seen as positive features in this map. This, however, is complicated by the flat bulk-solvent model which is almost universally used in modern crystallographic refinement programs. This model postulates constant electron density at any voxel of the unit-cell volume that is not occupied by the atomic model. Consequently, if the density arising from the omitted atoms is weak then the bulk-solvent model may obscure it further. A possible solution to this problem is to prevent bulk solvent from entering the selected OMIT regions, which may improve the interpretative power of residual maps. This approach is called a polder (OMIT) map. Polder OMIT maps can be particularly useful for displaying weak densities of ligands, solvent molecules, side chains, alternative conformations and residues both in terminal regions and in loops. The tools described in this manuscript have been implemented and are available in PHENIX.
Energy Technology Data Exchange (ETDEWEB)
Wiggenraad, R.; Verbeek-de Kanter, A.; Mast, M. [Radiotherapy Centre West, The Hague (Netherlands); Molenaar, R. [Diaconessenhuis, Leiden (Netherlands). Dept. of Neurology; Lycklama a Nijeholt, G. [Medical Centre Haagladen, The Hague (Netherlands). Dept. of Radiology; Vecht, C. [Medical Centre Haagladen, The Hague (Netherlands). Dept. of Neurology; Struikmans, H. [Radiotherapy Centre West, The Hague (Netherlands); Leiden Univ. Medical Centre (Netherlands). Dept. of Radiotherapy; Kal, H.B.
2012-08-15
Purpose: The 1-year local control rates after single-fraction stereotactic radiotherapy (SRT) for brain metastases > 3 cm diameter are less than 70%, but with fractionated SRT (FSRT) higher local control rates have been reported. The purpose of this study was to compare our treatment results with SRT and FSRT for large brain metastases. Materials and methods: In two consecutive periods, 41 patients with 46 brain metastases received SRT with 1 fraction of 15 Gy, while 51 patients with 65 brain metastases received FSRT with 3 fractions of 8 Gy. We included patients with brain metastases with a planning target volume of > 13 cm{sup 3} or metastases in the brainstem. Results: The minimum follow-up of patients still alive was 22 months. Comparing 1 fraction of 15 Gy with 3 fractions of 8 Gy, the 1-year rates of freedom from any local progression (54% and 61%, p = 0.93) and pseudo progression (85% and 75%, p = 0.25) were not significantly different. Overall survival rates were also not different. Conclusion: The 1-year local progression and pseudo progression rates after 1 fraction of 15 Gy or 3 fractions of 8 Gy for large brain metastases and metastases in the brainstem are similar. For better local control rates, FSRT schemes with a higher biological equivalent dose may be necessary. (orig.)
Fractional CO2 Laser Pretreatment Facilitates Transdermal Delivery of Two Vitamin C Derivatives
Directory of Open Access Journals (Sweden)
Chien-Yu Hsiao
2016-11-01
Full Text Available Background: Topical vitamin C derivatives have been used to treat melasma and used as a skin whitener. The aim of this study was to compare skin histology and permeation of l-ascorbic acid 2-phosphate sesquimagnesium salt (MAP-1 and magnesium l-ascorbic acid-2-phosphate (MAP-2 after fractional CO2 laser pretreatment. Methods: The effect of fractional laser treatment on porcine skin was examined by scanning electron microscopy and confocal laser scanning electron microscopy. The effect of fractional CO2 laser treatment of different fluencies and pass numbers on transdermal flux of the two vitamin C derivatives through porcine skin was examined in vitro using a Franz diffusion chamber. Results: Fluxes of MAP-1 and MAP-2 across fractional CO2 laser-treated (5 W skin were eight- to 13-fold, and 20- to 22-fold higher, respectively, than the fluxes of these compounds across intact skin. Fluxes of MAP-1 and MAP-2 across fractional CO2 laser-treated (9 W skin were 14- to 19-fold, and 30- to 42-fold higher, respectively, than their fluxes across intact skin. Conclusion: Fractional CO2 laser treatment is an effective way of delivering vitamin C derivatives into the skin.
Wang, Qingzhu; Chen, Xiaoming; Zhu, Yihai
2017-09-01
Existing image compression and encryption methods have several shortcomings: they have low reconstruction accuracy and are unsuitable for three-dimensional (3D) images. To overcome these limitations, this paper proposes a tensor-based approach adopting tensor compressive sensing and tensor discrete fractional random transform (TDFRT). The source video images are measured by three key-controlled sensing matrices. Subsequently, the resulting tensor image is further encrypted using 3D cat map and the proposed TDFRT, which is based on higher-order singular value decomposition. A multiway projection algorithm is designed to reconstruct the video images. The proposed algorithm can greatly reduce the data volume and improve the efficiency of the data transmission and key distribution. The simulation results validate the good compression performance, efficiency, and security of the proposed algorithm.
Zhong, Hualiang; Chetty, Indrin J.
2017-06-01
Tumor regression during the course of fractionated radiotherapy confounds the ability to accurately estimate the total dose delivered to tumor targets. Here we present a new criterion to improve the accuracy of image intensity-based dose mapping operations for adaptive radiotherapy for patients with non-small cell lung cancer (NSCLC). Six NSCLC patients were retrospectively investigated in this study. An image intensity-based B-spline registration algorithm was used for deformable image registration (DIR) of weekly CBCT images to a reference image. The resultant displacement vector fields were employed to map the doses calculated on weekly images to the reference image. The concept of energy conservation was introduced as a criterion to evaluate the accuracy of the dose mapping operations. A finite element method (FEM)-based mechanical model was implemented to improve the performance of the B-Spline-based registration algorithm in regions involving tumor regression. For the six patients, deformed tumor volumes changed by 21.2 ± 15.0% and 4.1 ± 3.7% on average for the B-Spline and the FEM-based registrations performed from fraction 1 to fraction 21, respectively. The energy deposited in the gross tumor volume (GTV) was 0.66 Joules (J) per fraction on average. The energy derived from the fractional dose reconstructed by the B-spline and FEM-based DIR algorithms in the deformed GTV’s was 0.51 J and 0.64 J, respectively. Based on landmark comparisons for the 6 patients, mean error for the FEM-based DIR algorithm was 2.5 ± 1.9 mm. The cross-correlation coefficient between the landmark-measured displacement error and the loss of radiation energy was -0.16 for the FEM-based algorithm. To avoid uncertainties in measuring distorted landmarks, the B-Spline-based registrations were compared to the FEM registrations, and their displacement differences equal 4.2 ± 4.7 mm on average. The displacement differences were
Zhong, Hualiang; Chetty, Indrin J
2017-06-07
Tumor regression during the course of fractionated radiotherapy confounds the ability to accurately estimate the total dose delivered to tumor targets. Here we present a new criterion to improve the accuracy of image intensity-based dose mapping operations for adaptive radiotherapy for patients with non-small cell lung cancer (NSCLC). Six NSCLC patients were retrospectively investigated in this study. An image intensity-based B-spline registration algorithm was used for deformable image registration (DIR) of weekly CBCT images to a reference image. The resultant displacement vector fields were employed to map the doses calculated on weekly images to the reference image. The concept of energy conservation was introduced as a criterion to evaluate the accuracy of the dose mapping operations. A finite element method (FEM)-based mechanical model was implemented to improve the performance of the B-Spline-based registration algorithm in regions involving tumor regression. For the six patients, deformed tumor volumes changed by 21.2 ± 15.0% and 4.1 ± 3.7% on average for the B-Spline and the FEM-based registrations performed from fraction 1 to fraction 21, respectively. The energy deposited in the gross tumor volume (GTV) was 0.66 Joules (J) per fraction on average. The energy derived from the fractional dose reconstructed by the B-spline and FEM-based DIR algorithms in the deformed GTV's was 0.51 J and 0.64 J, respectively. Based on landmark comparisons for the 6 patients, mean error for the FEM-based DIR algorithm was 2.5 ± 1.9 mm. The cross-correlation coefficient between the landmark-measured displacement error and the loss of radiation energy was -0.16 for the FEM-based algorithm. To avoid uncertainties in measuring distorted landmarks, the B-Spline-based registrations were compared to the FEM registrations, and their displacement differences equal 4.2 ± 4.7 mm on average. The displacement differences were
DEFF Research Database (Denmark)
Thuesen, Christian Langhoff; Koch, Christian
2011-01-01
trends as globalization. Three niches (Lean Construction, BIM and System Deliveries) are subject to a detailed analysis showing partly incompatible rationales and various degrees of innovation potential. The paper further discusses how existing policymaking operates in a number of tensions one being......, the innovation map can act as a medium in which policymakers, interest organization and companies can develop and coordinate future innovation activities....
DEFF Research Database (Denmark)
Scholderer, Joachim; Kügler, Jens; Olsen, Nina Veflen
2013-01-01
probabilities are subjected to multiple correspondence analysis and mapped into low-dimensional space. In a third step, the principal coordinates representing meal centres and side components in the correspondence analysis solution are subjected to cluster analysis to identify distinct groups of compatible...
DEFF Research Database (Denmark)
Gilje, Øystein; Frølunde, Lisbeth; Lindstrand, Fredrik
2010-01-01
This chapter concerns mapping patterns in regards to how young filmmakers (age 15 – 20) in the Scandinavian countries learn about filmmaking. To uncover the patterns, we present portraits of four young filmmakers who participated in the Scandinavian research project Making a filmmaker. The focus...
DEFF Research Database (Denmark)
Salovaara-Moring, Inka
of digital cartographies has been highlighted as the ‘processual turn’ in critical cartography, whereas in related computational journalism it can be seen as an interactive and iterative process of mapping complex and fragile ecological developments. This paper looks at computer-assisted cartography as part...
Heterogeneous fractionation profiles of meta-analytic coactivation networks.
Laird, Angela R; Riedel, Michael C; Okoe, Mershack; Jianu, Radu; Ray, Kimberly L; Eickhoff, Simon B; Smith, Stephen M; Fox, Peter T; Sutherland, Matthew T
2017-04-01
Computational cognitive neuroimaging approaches can be leveraged to characterize the hierarchical organization of distributed, functionally specialized networks in the human brain. To this end, we performed large-scale mining across the BrainMap database of coordinate-based activation locations from over 10,000 task-based experiments. Meta-analytic coactivation networks were identified by jointly applying independent component analysis (ICA) and meta-analytic connectivity modeling (MACM) across a wide range of model orders (i.e., d=20-300). We then iteratively computed pairwise correlation coefficients for consecutive model orders to compare spatial network topologies, ultimately yielding fractionation profiles delineating how "parent" functional brain systems decompose into constituent "child" sub-networks. Fractionation profiles differed dramatically across canonical networks: some exhibited complex and extensive fractionation into a large number of sub-networks across the full range of model orders, whereas others exhibited little to no decomposition as model order increased. Hierarchical clustering was applied to evaluate this heterogeneity, yielding three distinct groups of network fractionation profiles: high, moderate, and low fractionation. BrainMap-based functional decoding of resultant coactivation networks revealed a multi-domain association regardless of fractionation complexity. Rather than emphasize a cognitive-motor-perceptual gradient, these outcomes suggest the importance of inter-lobar connectivity in functional brain organization. We conclude that high fractionation networks are complex and comprised of many constituent sub-networks reflecting long-range, inter-lobar connectivity, particularly in fronto-parietal regions. In contrast, low fractionation networks may reflect persistent and stable networks that are more internally coherent and exhibit reduced inter-lobar communication. Copyright © 2017 Elsevier Inc. All rights reserved.
Gover, A. Rod; Waldron, Andrew
2017-09-01
We develop a universal distributional calculus for regulated volumes of metrics that are suitably singular along hypersurfaces. When the hypersurface is a conformal infinity we give simple integrated distribution expressions for the divergences and anomaly of the regulated volume functional valid for any choice of regulator. For closed hypersurfaces or conformally compact geometries, methods from a previously developed boundary calculus for conformally compact manifolds can be applied to give explicit holographic formulæ for the divergences and anomaly expressed as hypersurface integrals over local quantities (the method also extends to non-closed hypersurfaces). The resulting anomaly does not depend on any particular choice of regulator, while the regulator dependence of the divergences is precisely captured by these formulæ. Conformal hypersurface invariants can be studied by demanding that the singular metric obey, smoothly and formally to a suitable order, a Yamabe type problem with boundary data along the conformal infinity. We prove that the volume anomaly for these singular Yamabe solutions is a conformally invariant integral of a local Q-curvature that generalizes the Branson Q-curvature by including data of the embedding. In each dimension this canonically defines a higher dimensional generalization of the Willmore energy/rigid string action. Recently, Graham proved that the first variation of the volume anomaly recovers the density obstructing smooth solutions to this singular Yamabe problem; we give a new proof of this result employing our boundary calculus. Physical applications of our results include studies of quantum corrections to entanglement entropies.
Nootropic Effects of Filipendula Vulgaris Moench Water Extract Fractions.
Shilova, I V; Suslov, N I; Amelchenko, V P
2015-07-01
Nootropic activity of water extract fractions from aerial parts of Filipendula vulgaris Moench was demonstrated on the models of hermetic volume hypoxia, conditioned passive avoidance response, open field test, and forced swimming with a load. The fractions stimulated hypoxic resistance, normalized orientation and exploratory behavior, improved conditioned response reproduction during testing after hypoxic injury, and increased exercise tolerance. Fractionation of the extract led to dissociation of the effect components, which suggests that individual constituents have specific characteristics. Ethylacetate fraction exhibited most pronounced nootropic activity and was superior to plant extract by some characteristics. The detected effects seemed to be caused by modulation of the hippocampus activity the under the effects of phenol and triterpene compounds.
Stochastic calculus for fractional Brownian motion and related processes
Mishura, Yuliya S
2008-01-01
The theory of fractional Brownian motion and other long-memory processes are addressed in this volume. Interesting topics for PhD students and specialists in probability theory, stochastic analysis and financial mathematics demonstrate the modern level of this field. Among these are results about Levy characterization of fractional Brownian motion, maximal moment inequalities for Wiener integrals including the values 0
T1-Mapping and Outcome in Nonischemic Cardiomyopathy: All-Cause Mortality and Heart Failure.
Puntmann, Valentina O; Carr-White, Gerry; Jabbour, Andrew; Yu, Chung-Yao; Gebker, Rolf; Kelle, Sebastian; Hinojar, Rocio; Doltra, Adelina; Varma, Niharika; Child, Nicholas; Rogers, Toby; Suna, Gonca; Arroyo Ucar, Eduardo; Goodman, Ben; Khan, Sitara; Dabir, Darius; Herrmann, Eva; Zeiher, Andreas M; Nagel, Eike
2016-01-01
The study sought to examine prognostic relevance of T1 mapping parameters (based on a T1 mapping method) in nonischemic dilated cardiomyopathy (NIDCM) and compare them with conventional markers of adverse outcome. NIDCM is a recognized cause of poor clinical outcome. NIDCM is characterized by intrinsic myocardial remodeling due to complex pathophysiological processes affecting myocardium diffusely. Lack of accurate and noninvasive characterization of diffuse myocardial disease limits recognition of early cardiomyopathy and effective clinical management in NIDCM. Cardiac magnetic resonance (CMR) supports detection of diffuse myocardial disease by T1 mapping. This is a prospective observational multicenter longitudinal study in 637 consecutive patients with dilated NIDCM (mean age 50 years [interquartile range: 37 to 76 years]; 395 males [62%]) undergoing CMR with T1 mapping and late gadolinium enhancement (LGE) at 1.5-T and 3.0-T. The primary endpoint was all-cause mortality. A composite of heart failure (HF) mortality and hospitalization was a secondary endpoint. During a median follow-up period of 22 months (interquartile range: 19 to 25 months), we observed a total of 28 deaths (22 cardiac) and 68 composite HF events. T1 mapping indices (native T1 and extracellular volume fraction), as well as the presence and extent of LGE, were predictive of all-cause mortality and HF endpoint (p T1 was the sole independent predictor of all-cause and HF composite endpoints (hazard ratio: 1.1; 95% confidence interval: 1.06 to 1.15; hazard ratio: 1.1; 95% confidence interval: 1.05 to 1.1; p T1 mapping are significantly predictive of all-cause mortality and HF events in NIDCM. We provide a basis for a novel algorithm of risk stratification in NIDCM using a complementary assessment of diffuse and regional disease by T1 mapping and LGE, respectively. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Ranga B. Myneni
2013-02-01
Full Text Available Long-term global data sets of vegetation Leaf Area Index (LAI and Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR are critical to monitoring global vegetation dynamics and for modeling exchanges of energy, mass and momentum between the land surface and planetary boundary layer. LAI and FPAR are also state variables in hydrological, ecological, biogeochemical and crop-yield models. The generation, evaluation and an example case study documenting the utility of 30-year long data sets of LAI and FPAR are described in this article. A neural network algorithm was first developed between the new improved third generation Global Inventory Modeling and Mapping Studies (GIMMS Normalized Difference Vegetation Index (NDVI3g and best-quality Terra Moderate Resolution Imaging Spectroradiometer (MODIS LAI and FPAR products for the overlapping period 2000–2009. The trained neural network algorithm was then used to generate corresponding LAI3g and FPAR3g data sets with the following attributes: 15-day temporal frequency, 1/12 degree spatial resolution and temporal span of July 1981 to December 2011. The quality of these data sets for scientific research in other disciplines was assessed through (a comparisons with field measurements scaled to the spatial resolution of the data products, (b comparisons with broadly-used existing alternate satellite data-based products, (c comparisons to plant growth limiting climatic variables in the northern latitudes and tropical regions, and (d correlations of dominant modes of interannual variability with large-scale circulation anomalies such as the EI Niño-Southern Oscillation and Arctic Oscillation. These assessment efforts yielded results that attested to the suitability of these data sets for research use in other disciplines. The utility of these data sets is documented by comparing the seasonal profiles of LAI3g with profiles from 18 state-of-the-art Earth System Models: the models
Rapid mapping of volumetric errors
Energy Technology Data Exchange (ETDEWEB)
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.
Park, No-Wook; Jang, Dong-Ho
2014-01-01
This paper compares the predictive performance of different geostatistical kriging algorithms for intertidal surface sediment facies mapping using grain size data. Indicator kriging, which maps facies types from conditional probabilities of predefined facies types, is first considered. In the second approach, grain size fractions are first predicted using cokriging and the facies types are then mapped. As grain size fractions are compositional data, their characteristics should be considered during spatial prediction. For efficient prediction of compositional data, additive log-ratio transformation is applied before cokriging analysis. The predictive performance of cokriging of the transformed variables is compared with that of cokriging of raw fractions in terms of both prediction errors of fractions and facies mapping accuracy. From a case study of the Baramarae tidal flat, Korea, the mapping method based on cokriging of log-ratio transformation of fractions outperformed the one based on cokriging of untransformed fractions in the prediction of fractions and produced the best facies mapping accuracy. Indicator kriging that could not account for the variation of fractions within each facies type showed the worst mapping accuracy. These case study results indicate that the proper processing of grain size fractions as compositional data is important for reliable facies mapping.
Fractional random walk lattice dynamics
Michelitsch, T. M.; Collet, B. A.; Riascos, A. P.; Nowakowski, A. F.; Nicolleau, F. C. G. A.
2017-02-01
We analyze time-discrete and time-continuous ‘fractional’ random walks on undirected regular networks with special focus on cubic periodic lattices in n = 1, 2, 3,.. dimensions. The fractional random walk dynamics is governed by a master equation involving fractional powers of Laplacian matrices {{L}\\fracα{2}}} where α =2 recovers the normal walk. First we demonstrate that the interval 0<α ≤slant 2 is admissible for the fractional random walk. We derive analytical expressions for the transition matrix of the fractional random walk and closely related the average return probabilities. We further obtain the fundamental matrix {{Z}(α )} , and the mean relaxation time (Kemeny constant) for the fractional random walk. The representation for the fundamental matrix {{Z}(α )} relates fractional random walks with normal random walks. We show that the matrix elements of the transition matrix of the fractional random walk exihibit for large cubic n-dimensional lattices a power law decay of an n-dimensional infinite space Riesz fractional derivative type indicating emergence of Lévy flights. As a further footprint of Lévy flights in the n-dimensional space, the transition matrix and return probabilities of the fractional random walk are dominated for large times t by slowly relaxing long-wave modes leading to a characteristic {{t}-\\frac{n{α}} -decay. It can be concluded that, due to long range moves of fractional random walk, a small world property is emerging increasing the efficiency to explore the lattice when instead of a normal random walk a fractional random walk is chosen.
DEFF Research Database (Denmark)
Thuesen, Christian Langhoff; Koch, Christian
2011-01-01
By adopting a theoretical framework from strategic niche management research (SNM) this paper presents an analysis of the innovation system of the Danish Construction industry. The analysis shows a multifaceted landscape of innovation around an existing regime, built around existing ways of working...... and developed over generations. The regime is challenged from various niches and the socio-technical landscape through trends as globalization. Three niches (Lean Construction, BIM and System Deliveries) are subject to a detailed analysis showing partly incompatible rationales and various degrees of innovation...... potential. The paper further discusses how existing policymaking operates in a number of tensions one being between government and governance. Based on the concepts from SNM the paper introduces an innovation map in order to support the development of meta-governance policymaking. By mapping some...
Fractions, Number Lines, Third Graders
Cramer, Kathleen; Ahrendt, Sue; Monson, Debra; Wyberg, Terry; Colum, Karen
2017-01-01
The Common Core State Standards for Mathematics (CCSSM) (CCSSI 2010) outlines ambitious goals for fraction learning, starting in third grade, that include the use of the number line model. Understanding and constructing fractions on a number line are particularly complex tasks. The current work of the authors centers on ways to successfully…
Unwrapping Students' Ideas about Fractions
Lewis, Rebecca M.; Gibbons, Lynsey K.; Kazemi, Elham; Lind, Teresa
2015-01-01
Supporting students to develop an understanding of the meaning of fractions is an important goal of elementary school mathematics. This involves developing partitioning strategies, creating representations, naming fractional quantities, and using symbolic notation. This article describes how teachers can use a formative assessment problem to…
Understanding Magnitudes to Understand Fractions
Gabriel, Florence
2016-01-01
Fractions are known to be difficult to learn and difficult to teach, yet they are vital for students to have access to further mathematical concepts. This article uses evidence to support teachers employing teaching methods that focus on the conceptual understanding of the magnitude of fractions.
Financial Planning with Fractional Goals
M.H. Goedhart; J. Spronk (Jaap)
1995-01-01
textabstractWhen solving financial planning problems with multiple goals by means of multiple objective programming, the presence of fractional goals leads to technical difficulties. In this paper we present a straightforward interactive approach for solving such linear fractional programs with
Fractional Kinetics of Chaotic Dynamics of Particles in Complex Systems
2009-12-31
equivalent to the Volterra integral equation of the second kind [24-26] x(t) = Pi ta-\\ ta-2 r(o) r(o -1) K /-sin[x(T)]i:~0«(f-n)dT — ( r(a)J (t...maps from fractional differential equations , we use the equivalence of the Cauchy-type problems and to the nonlinear Volterra integral equations of...equivalence of the differential equation with Riemann-Liouville and Caputo fractional derivatives and the Volterra integral equation . This approach is
Volumetric Spectroscopic Imaging of Glioblastoma Multiforme Radiation Treatment Volumes
Energy Technology Data Exchange (ETDEWEB)
Parra, N. Andres [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Maudsley, Andrew A. [Department of Radiology, University of Miami Miller School of Medicine, Miami, Florida (United States); Gupta, Rakesh K. [Department of Radiology and Imaging, Fortis Memorial Research Institute, Gurgaon, Haryana (India); Ishkanian, Fazilat; Huang, Kris [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Walker, Gail R. [Biostatistics and Bioinformatics Core Resource, Sylvester Cancer Center, University of Miami Miller School of Medicine, Miami, Florida (United States); Padgett, Kyle [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Department of Radiology, University of Miami Miller School of Medicine, Miami, Florida (United States); Roy, Bhaswati [Department of Radiology and Imaging, Fortis Memorial Research Institute, Gurgaon, Haryana (India); Panoff, Joseph; Markoe, Arnold [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Stoyanova, Radka, E-mail: RStoyanova@med.miami.edu [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States)
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
Radiating subdispersive fractional optical solitons
Energy Technology Data Exchange (ETDEWEB)
Fujioka, J., E-mail: fujioka@fisica.unam.mx; Espinosa, A.; Rodríguez, R. F. [Departamento de Física Química, Instituto de Física, Universidad Nacional Autónoma de México, Mexico, DF 04510 (Mexico); Malomed, B. A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)
2014-09-01
It was recently found [Fujioka et al., Phys. Lett. A 374, 1126 (2010)] that the propagation of solitary waves can be described by a fractional extension of the nonlinear Schrödinger (NLS) equation which involves a temporal fractional derivative (TFD) of order α > 2. In the present paper, we show that there is also another fractional extension of the NLS equation which contains a TFD with α < 2, and in this case, the new equation describes the propagation of radiating solitons. We show that the emission of the radiation (when α < 2) is explained by resonances at various frequencies between the pulses and the linear modes of the system. It is found that the new fractional NLS equation can be derived from a suitable Lagrangian density, and a fractional Noether's theorem can be applied to it, thus predicting the conservation of the Hamiltonian, momentum and energy.
A new fractional wavelet transform
Dai, Hongzhe; Zheng, Zhibao; Wang, Wei
2017-03-01
The fractional Fourier transform (FRFT) is a potent tool to analyze the time-varying signal. However, it fails in locating the fractional Fourier domain (FRFD)-frequency contents which is required in some applications. A novel fractional wavelet transform (FRWT) is proposed to solve this problem. It displays the time and FRFD-frequency information jointly in the time-FRFD-frequency plane. The definition, basic properties, inverse transform and reproducing kernel of the proposed FRWT are considered. It has been shown that an FRWT with proper order corresponds to the classical wavelet transform (WT). The multiresolution analysis (MRA) associated with the developed FRWT, together with the construction of the orthogonal fractional wavelets are also presented. Three applications are discussed: the analysis of signal with time-varying frequency content, the FRFD spectrum estimation of signals that involving noise, and the construction of fractional Harr wavelet. Simulations verify the validity of the proposed FRWT.
Hinojar, Rocio; Varma, Niharika; Child, Nick; Goodman, Benjamin; Jabbour, Andrew; Yu, Chung-Yao; Gebker, Rolf; Doltra, Adelina; Kelle, Sebastian; Khan, Sitara; Rogers, Toby; Arroyo Ucar, Eduardo; Cummins, Ciara; Carr-White, Gerald; Nagel, Eike; Puntmann, Valentina O
2015-12-01
The differential diagnosis of left ventricular (LV) hypertrophy remains challenging in clinical practice, in particular, between hypertrophic cardiomyopathy (HCM) and increased LV wall thickness because of systemic hypertension. Diffuse myocardial disease is a characteristic feature in HCM, and an early manifestation of sarcomere-gene mutations in subexpressed family members (G+P- subjects). This study aimed to investigate whether detecting diffuse myocardial disease by T1 mapping can discriminate between HCM versus hypertensive heart disease as well as to detect genetically driven interstitial changes in the G+P- subjects. Patients with diagnoses of HCM or hypertension (HCM, n=95; hypertension, n=69) and G+P- subjects (n=23) underwent a clinical cardiovascular magnetic resonance protocol (3 tesla) for cardiac volumes, function, and scar imaging. T1 mapping was performed before and >20 minutes after administration of 0.2 mmol/kg of gadobutrol. Native T1 and extracellular volume fraction were significantly higher in HCM compared with patients with hypertension (P15 mm (P2 SD above the mean of the normal range. Native T1 was an independent discriminator between HCM and hypertension, over and above extracellular volume fraction, LV wall thickness and indexed LV mass. Native T1 was also useful in separating G+P- subjects from controls. Native T1 may be applied to discriminate between HCM and hypertensive heart disease and detect early changes in G+P- subjects. © 2015 American Heart Association, Inc.
High-order fractional partial differential equation transform for molecular surface construction.
Hu, Langhua; Chen, Duan; Wei, Guo-Wei
2013-01-01
Fractional derivative or fractional calculus plays a significant role in theoretical modeling of scientific and engineering problems. However, only relatively low order fractional derivatives are used at present. In general, it is not obvious what role a high fractional derivative can play and how to make use of arbitrarily high-order fractional derivatives. This work introduces arbitrarily high-order fractional partial differential equations (PDEs) to describe fractional hyperdiffusions. The fractional PDEs are constructed via fractional variational principle. A fast fractional Fourier transform (FFFT) is proposed to numerically integrate the high-order fractional PDEs so as to avoid stringent stability constraints in solving high-order evolution PDEs. The proposed high-order fractional PDEs are applied to the surface generation of proteins. We first validate the proposed method with a variety of test examples in two and three-dimensional settings. The impact of high-order fractional derivatives to surface analysis is examined. We also construct fractional PDE transform based on arbitrarily high-order fractional PDEs. We demonstrate that the use of arbitrarily high-order derivatives gives rise to time-frequency localization, the control of the spectral distribution, and the regulation of the spatial resolution in the fractional PDE transform. Consequently, the fractional PDE transform enables the mode decomposition of images, signals, and surfaces. The effect of the propagation time on the quality of resulting molecular surfaces is also studied. Computational efficiency of the present surface generation method is compared with the MSMS approach in Cartesian representation. We further validate the present method by examining some benchmark indicators of macromolecular surfaces, i.e., surface area, surface enclosed volume, surface electrostatic potential and solvation free energy. Extensive numerical experiments and comparison with an established surface model
UHECR Maps: mysteries and surprises
Fargion, D.
2010-01-01
The rise of nucleon UHECR above GZK astronomy made by protons is puzzled by three main mysteries: an unexpected nearby Virgo UHECR suppression, a rich crowded clustering frozen vertically (north-south) along Cen A, a composition suggesting nuclei and not nucleons. The UHECR map, initially consistent with GZK volumes, to day seem to be not much correlated with expected Super Galactic Plane. Moreover slant depth data of UHECR from AUGER airshower shape do not favor the proton but points to a nu...
Ferroelectric Fractional-Order Capacitors
Agambayev, Agamyrat
2017-07-25
Poly(vinylidene fluoride)-based polymers and their blends are used to fabricate electrostatic fractional-order capacitors. This simple but effective method allows us to precisely tune the constant phase angle of the resulting fractional-order capacitor by changing the blend composition. Additionally, we have derived an empirical relation between the ratio of the blend constituents and the constant phase angle to facilitate the design of a fractional order capacitor with a desired constant phase angle. The structural composition of the fabricated blends is investigated using Fourier transform infrared spectroscopy and X-ray diffraction techniques.
Intelligent fractions learning system: implementation
CSIR Research Space (South Africa)
Smith, Adrew C
2011-05-01
Full Text Available surface, manipulatives, mobile phone, fractions, developing region, Montessori-inspired manipulatives. 1. Introduction A set of fraction blocks is a tool to learn about fractions, often used in schools. With large classes often in excess of 35 children... children prefer using manipulatives instead of on-screen interfaces [2]. However, with the poor teacher-to-student ratio in developing regions it is hardly possible for the teacher to take note of the children?s use of the available tools. In developing...
On Generalized Fractional Differentiator Signals
Directory of Open Access Journals (Sweden)
Hamid A. Jalab
2013-01-01
Full Text Available By employing the generalized fractional differential operator, we introduce a system of fractional order derivative for a uniformly sampled polynomial signal. The calculation of the bring in signal depends on the additive combination of the weighted bring-in of N cascaded digital differentiators. The weights are imposed in a closed formula containing the Stirling numbers of the first kind. The approach taken in this work is to consider that signal function in terms of Newton series. The convergence of the system to a fractional time differentiator is discussed.
Relationship between fractional calculus and fractional Fourier transform
Zhang, Yanshan; Zhang, Feng; Lu, Mingfeng
2015-09-01
The fractional calculus (FC) deals with integrals and derivatives of arbitrary (i.e., non-integer) order, and shares its origins with classical integral and differential calculus. The fractional Fourier transform (FRFT), which has been found having many applications in optics and other areas, is a generalization of the usual Fourier transform. The FC and the FRFT are two of the most interesting and useful fractional areas. In recent years, it appears many papers on the FC and FRFT, however, few of them discuss the connection of the two fractional areas. We study their relationship. The relational expression between them is deduced. The expectation of interdisciplinary cross fertilization is our motivation. For example, we can use the properties of the FC (non-locality, etc.) to solve the problem which is difficult to be solved by the FRFT in optical engineering; we can also through the physical meaning of the FRFT optical implementation to explain the physical meaning of the FC. The FC and FRFT approaches can be transposed each other in the two fractional areas. It makes that the success of the fractional methodology is unquestionable with a lot of applications, namely in nonlinear and complex system dynamics and image processing.
Falcão, Renato Pinto de Queiroz
2003-01-01
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção. Esta dissertação apresenta uma ferramenta de apoio à decisão, baseada na Metodologia Multicritérios de Apoio à Decisão - MCDA, através do desenvolvimento de um software denominado Reasoning Maps. O software permite, de maneira integrada, a construção de mapas cognitivos, suas diversas análises topológicas e o cadastramento e análise de alternativas. Abor...
DEFF Research Database (Denmark)
Dehlholm, Christian; Brockhoff, Per B.; Bredie, Wender Laurentius Petrus
2012-01-01
instructions and influence heavily the product placements and the descriptive vocabulary (Dehlholm et.al., 2012b). The type of assessors performing the method influences results with an extra aspect in Projective Mapping compared to more analytical tests, as the given spontaneous perceptions are much dependent...... the applied framework, semantic restrictions, the choice of type of assessors and the validation of product separations. The applied framework concerns the response surface as presented to the assessor in different shapes, e.g. rectangular, square or round. Semantic restrictions are a part of the assessor...
Advanced Hough transform using a multilayer fractional Fourier method.
Shi, Daming; Zheng, Liying; Liu, Jigang
2010-06-01
The Hough transform (HT) is a commonly used technique for the identification of straight lines in an image. The Hough transform can be equivalently computed using the Radon transform (RT), by performing line detection in the frequency domain through use of central-slice theorem. In this research, an advanced Radon transform is developed using a multilayer fractional Fourier transform, a Cartesian-to-polar mapping, and 1-D inverse Fourier transforms, followed by peak detection in the sinogram. The multilayer fractional Fourier transform achieves a more accurate sampling in the frequency domain, and requires no zero padding at the stage of Cartesian-to-polar coordinate mapping. Our experiments were conducted on mix-shape images, noisy images, mixed-thickness lines and a large data set consisting of 751,000 handwritten Chinese characters. The experimental results have shown that our proposed method outperforms all known representative line detection methods based on the standard Hough transform or the Fourier transform.
Ugander, Martin; Oki, Abiola J; Hsu, Li-Yueh; Kellman, Peter; Greiser, Andreas; Aletras, Anthony H; Sibley, Christopher T; Chen, Marcus Y; Bandettini, W Patricia; Arai, Andrew E
2012-05-01
Conventional late gadolinium enhancement (LGE) cardiac magnetic resonance can detect myocardial infarction and some forms of non-ischaemic myocardial fibrosis. However, quantitative imaging of extracellular volume fraction (ECV) may be able to detect subtle abnormalities such as diffuse fibrosis or post-infarct remodelling of remote myocardium. The aims were (1) to measure ECV in myocardial infarction and non-ischaemic myocardial fibrosis, (2) to determine whether ECV varies with age, and (3) to detect sub-clinical abnormalities in 'normal appearing' myocardium remote from regions of infarction. Cardiac magnetic resonance ECV imaging was performed in 126 patients with T1 mapping before and after injection of gadolinium contrast. Conventional LGE images were acquired for the left ventricle. In patients with a prior myocardial infarction, the infarct region had an ECV of 51 ± 8% which did not overlap with the remote 'normal appearing' myocardium that had an ECV of 27 ± 3% (P infarctions increased as left ventricular ejection fraction decreased (r = -0.50, P = 0.02). Extracellular volume fraction imaging can quantitatively characterize myocardial infarction, atypical diffuse fibrosis, and subtle myocardial abnormalities not clinically apparent on LGE images. Taken within the context of prior literature, these subtle ECV abnormalities are consistent with diffuse fibrosis related to age and changes remote from infarction.
Ugander, Martin; Oki, Abiola J.; Hsu, Li-Yueh; Kellman, Peter; Greiser, Andreas; Aletras, Anthony H.; Sibley, Christopher T.; Chen, Marcus Y.; Bandettini, W. Patricia; Arai, Andrew E.
2012-01-01
Aims Conventional late gadolinium enhancement (LGE) cardiac magnetic resonance can detect myocardial infarction and some forms of non-ischaemic myocardial fibrosis. However, quantitative imaging of extracellular volume fraction (ECV) may be able to detect subtle abnormalities such as diffuse fibrosis or post-infarct remodelling of remote myocardium. The aims were (1) to measure ECV in myocardial infarction and non-ischaemic myocardial fibrosis, (2) to determine whether ECV varies with age, and (3) to detect sub-clinical abnormalities in ‘normal appearing’ myocardium remote from regions of infarction. Methods and results Cardiac magnetic resonance ECV imaging was performed in 126 patients with T1 mapping before and after injection of gadolinium contrast. Conventional LGE images were acquired for the left ventricle. In patients with a prior myocardial infarction, the infarct region had an ECV of 51 ± 8% which did not overlap with the remote ‘normal appearing’ myocardium that had an ECV of 27 ± 3% (P myocardial infarctions increased as left ventricular ejection fraction decreased (r = −0.50, P = 0.02). Conclusion Extracellular volume fraction imaging can quantitatively characterize myocardial infarction, atypical diffuse fibrosis, and subtle myocardial abnormalities not clinically apparent on LGE images. Taken within the context of prior literature, these subtle ECV abnormalities are consistent with diffuse fibrosis related to age and changes remote from infarction. PMID:22279111
Directory of Open Access Journals (Sweden)
Rob Alkemade
2011-09-01
Full Text Available Mapping ecosystem services (ESs is an important tool for providing the quantitative information necessary for the optimal use and protection of ecosystems and biodiversity. A common mapping approach is to apply established empirical relationships to ecosystem property maps. Often, ecosystem properties that provide services to humanity are strongly related to the land use and land cover, where the spatial allocation of the land cover in the landscape is especially important. Land use and land cover maps are, therefore, essential for ES mapping. However, insight into the uncertainties in land cover maps and how these propagate into ES maps is lacking. To analyze the effects of these uncertainties, we mapped pollination efficiency as an example of an ecosystem function, using two continental-scale land cover maps and two global-scale land cover maps. We compared the outputs with maps based on a detailed national-scale map. The ecosystem properties and functions could be mapped using the GLOBCOVER map with a reasonable to good accuracy. In homogeneous landscapes, an even coarser resolution map would suffice. For mapping ESs that depend on the spatial allocation of land cover in the landscape, a classification of satellite images using fractional land cover or mosaic classes is an asset.
aus dem Siepen, Fabian; Buss, Sebastian J; Messroghli, Daniel; Andre, Florian; Lossnitzer, Dirk; Seitz, Sebastian; Keller, Marius; Schnabel, Philipp A; Giannitsis, Evangelos; Korosoglou, Grigorios; Katus, Hugo A; Steen, Henning
2015-02-01
The aim of this study was to determine the value of extracellular volume fraction (ECV) for the non-invasive assessment of diffuse myocardial fibrosis (MF) in different stages of systolic left ventricular (LV) dysfunction in dilated cardiomyopathy (DCM) in comparison with endomyocardial biopsy. Non-invasive ECV assessment using cardiovascular magnetic resonance (CMR) T1 mapping reflects diffuse MF in patients with severe DCM, but earlier stages of DCM with mild LV functional impairment have not been investigated yet. Forty-five subjects with mild functional impairment and LV dilation ['early DCM', ejection fraction (EF) 45-55%], 29 with LV dysfunction and volume dilatation ('DCM', EF ECV. The collagen volume fraction (CVF) was quantified histologically from endomyocardial biopsies of 24 DCM patients out of the study cohort. The ECV between 'early DCM' (25 ± 4%), 'DCM' (27 ± 4%), and controls (23 ± 3; P ECV and EF (r = -0.35; P ECV and CVF could be detected (r = 0.85; P = 0.01). The cut-off value for ECV to differentiate between healthy myocardium and DCM was 26% (specificity 91.1%, sensitivity 62.1%, area under the curve 0.8, P ECV is already elevated at early stages of functional impairment, whereby an overlap between early DCM and controls is present. But 31% of the early DCM patients had an ECV fraction above the mean ±2 SD ECV of controls. ECV measurement with CMR reflects myocardial collagen content in DCM. Therefore, CMR-based assessment of ECV may have the potential to serve as a non-invasive tool for the quantification of diffuse MF in order to monitor therapy response and aid risk stratification in different stages of DCM. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.
Directory of Open Access Journals (Sweden)
Sayed M. Arafat
2014-06-01
Full Text Available Land cover map of North Sinai was produced based on the FAO-Land Cover Classification System (LCCS of 2004. The standard FAO classification scheme provides a standardized system of classification that can be used to analyze spatial and temporal land cover variability in the study area. This approach also has the advantage of facilitating the integration of Sinai land cover mapping products to be included with the regional and global land cover datasets. The total study area is covering a total area of 20,310.4 km2 (203,104 hectare. The landscape classification was based on SPOT4 data acquired in 2011 using combined multispectral bands of 20 m spatial resolution. Geographic Information System (GIS was used to manipulate the attributed layers of classification in order to reach the maximum possible accuracy. GIS was also used to include all necessary information. The identified vegetative land cover classes of the study area are irrigated herbaceous crops, irrigated tree crops and rain fed tree crops. The non-vegetated land covers in the study area include bare rock, bare soils (stony, very stony and salt crusts, loose and shifting sands and sand dunes. The water bodies were classified as artificial perennial water bodies (fish ponds and irrigated canals and natural perennial water bodies as lakes (standing. The artificial surfaces include linear and non-linear features.
Sequence finishing and mapping of Drosophila melanogasterheterochromatin
Energy Technology Data Exchange (ETDEWEB)
Hoskins, Roger A.; Carlson, Joseph W.; Kennedy, Cameron; Acevedo,David; Evans-Holm, Martha; Frise, Erwin; Wan, Kenneth H.; Park, Soo; Mendez-Lago, Maria; Rossi, Fabrizio; Villasante, Alfredo; Dimitri,Patrizio; Karpen, Gary H.; Celniker, Susan E.
2007-06-15
Genome sequences for most metazoans are incomplete due tothe presence of repeated DNA in the pericentromeric heterochromatin. Theheterochromatic regions of D. melanogaster contain 20 Mb of sequenceamenable to mapping, sequence assembly and finishing. Here we describethe generation of 15 Mb of finished or improved heterochromatic sequenceusing available clone resources and assembly and mapping methods. We alsoconstructed a BAC-based physical map that spans approximately 13 Mb ofthe pericentromeric heterochromatin, and a cytogenetic map that positionsapproximately 11 Mb of BAC contigs and sequence scaffolds in specificchromosomal locations. The integrated sequence assembly and maps greatlyimprove our understanding of the structure and composition of this poorlyunderstood fraction of a metazoan genome and provide a framework forfunctional analyses.
Australia's Next Top Fraction Model
Gould, Peter
2013-01-01
Peter Gould suggests Australia's next top fraction model should be a linear model rather than an area model. He provides a convincing argument and gives examples of ways to introduce a linear model in primary classrooms.
Physcicists rewarded for 'fractional electrons'
Ball, P
1998-01-01
The 1998 Nobel prize for physics has been awarded to Horst Stormer, Daniel Tsui and Robert Laughlin.Stormer and Tsui were the first to observe the fractional quantum Hall effect and Laughlin provided the theory shortly afterwards (1 page).
Fractional Transmission Line with Losses
Gómez-Aguilar, José Francisco; Dumitru, Baleanu
2014-11-01
In this manuscript, the fractional transmission line with losses is presented. The order of the Caputo derivative is considered as 0 Mittag-Leffler functions. The classic cases are recovered when β and γ are equal to 1.
Commercial SNF Accident Release Fractions
Energy Technology Data Exchange (ETDEWEB)
J. Schulz
2004-11-05
The purpose of this analysis is to specify and document the total and respirable fractions for radioactive materials that could be potentially released from an accident at the repository involving commercial spent nuclear fuel (SNF) in a dry environment. The total and respirable release fractions are used to support the preclosure licensing basis for the repository. The total release fraction is defined as the fraction of total commercial SNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. Radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses; this subset of the total release fraction is referred to as the respirable release fraction. Accidents may involve waste forms characterized as: (1) bare unconfined intact fuel assemblies, (2) confined intact fuel assemblies, or (3) canistered failed commercial SNF. Confined intact commercial SNF assemblies at the repository are contained in shipping casks, canisters, or waste packages. Four categories of failed commercial SNF are identified: (1) mechanically and cladding-penetration damaged commercial SNF, (2) consolidated/reconstituted assemblies, (3) fuel rods, pieces, and debris, and (4) nonfuel components. It is assumed that failed commercial SNF is placed into waste packages with a mesh screen at each end (CRWMS M&O 1999). In contrast to bare unconfined fuel assemblies, the
A Dream of the Perfect Map – Calvino’s Invisible Cities
Directory of Open Access Journals (Sweden)
Mario Vrbančić
2012-06-01
monsters; cartographers were involved in the production of abstract and functional systems based on mathematically rigorous depiction. By conceiving space as abstract, homogenous and universal, perspectivism and mathematical mapping enabled the era of great discoveries and colonization. Since then, the world has become more and more enmeshed in different maps, in different spaces, including that without volume, a new immaterial space of digital being. By constantly increasing digital connections of one site with thousands of others, cyberspace branches out in many directions at once, creating a labyrinthine web. Its expansion parallels the latest theory of cosmology, of an ‘inflationary’ period, during which the whole cosmos swelled from a microscopic point smaller than a proton to the size of a grapefruit in a fraction of a second. Paradoxically, we live in an ambiguous spatial construction: on one hand there seems to be a perfect map of the Empire that covers the territory (modern science masters both micro and macro worlds ever more precisely; on the other hand social theory reflects an overwhelming disorientation and confusion, characteristics of an existence within ‘the ruins of the Map’. However, both premises of Borges’ parable appear to be confusing. The map that covers the territory would confuse a traveller: does one navigate the actual or the virtual? Is the perfect map that would be a substitute for reality possible? Do we live in the ‘Tattered Ruins of that Map’? Maybe the map does not mirror the real, but precedes the territory and opens new, as yet undiscovered spaces. Or, better still, we should invent new maps. Borges’ parable teems with many readings describing postmodern cartography’s attempt to map the territory, or reality, and at the same time show the impossibility of such an endeavour.
Energy Technology Data Exchange (ETDEWEB)
Waghorn, Ben J; Shah, Amish P; Ngwa, Wilfred; Meeks, Sanford L; Langen, Katja M [Department of Radiation Oncology, M. D. Anderson Cancer Center Orlando, 1400 South Orange Avenue, Orlando, FL 32806 (United States); Moore, Joseph A; Siebers, Jeffrey V, E-mail: benjamin.waghorn@orlandohealth.co [Department of Radiation Oncology, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298 (United States)
2010-07-21
Intra-fraction organ motion during intensity-modulated radiation therapy (IMRT) treatment can cause differences between the planned and the delivered dose distribution. To investigate the extent of these dosimetric changes, a computational model was developed and validated. The computational method allows for calculation of the rigid motion perturbed three-dimensional dose distribution in the CT volume and therefore a dose volume histogram-based assessment of the dosimetric impact of intra-fraction motion on a rigidly moving body. The method was developed and validated for both step-and-shoot IMRT and solid compensator IMRT treatment plans. For each segment (or beam), fluence maps were exported from the treatment planning system. Fluence maps were shifted according to the target position deduced from a motion track. These shifted, motion-encoded fluence maps were then re-imported into the treatment planning system and were used to calculate the motion-encoded dose distribution. To validate the accuracy of the motion-encoded dose distribution the treatment plan was delivered to a moving cylindrical phantom using a programmed four-dimensional motion phantom. Extended dose response (EDR-2) film was used to measure a planar dose distribution for comparison with the calculated motion-encoded distribution using a gamma index analysis (3% dose difference, 3 mm distance-to-agreement). A series of motion tracks incorporating both inter-beam step-function shifts and continuous sinusoidal motion were tested. The method was shown to accurately predict the film's dose distribution for all of the tested motion tracks, both for the step-and-shoot IMRT and compensator plans. The average gamma analysis pass rate for the measured dose distribution with respect to the calculated motion-encoded distribution was 98.3 {+-} 0.7%. For static delivery the average film-to-calculation pass rate was 98.7 {+-} 0.2%. In summary, a computational technique has been developed to calculate the
Fractional Charge Definitions and Conditions
Energy Technology Data Exchange (ETDEWEB)
Goldhaber, A.S.
2004-06-04
Fractional charge is known through theoretical and experimental discoveries of isolable objects carrying fractions of familiar charge units--electric charge Q, spin S, and the difference of baryon and lepton numbers B-L. With a few simple assumptions all these effects may be described using a generalized version of charge renormalization for locally conserved charges, in which medium correlations yield familiar adiabatic, continuous renormalization, or sometimes nonadiabatic, discrete renormalization. Fractional charges may be carried by fundamental particles or fundamental solitons. Either picture works for the simplest fractional-quantum-Hall-effect quasiholes, though the particle description is far more general. The only known fundamental solitons in three or fewer space dimensions d are the kink (d = 1), the vortex (d = 2), and the magnetic monopole (d = 3). Further, for a charge not intrinsically coupled to the topological charge of a soliton, only the kink and the monopole may carry fractional values. The same reasoning enforces fractional values of B-L for electrically charged elementary particles.
DEFF Research Database (Denmark)
Carruth, Susan
2015-01-01
Resilience theory is a growing discipline with great relevance for the discipline of planning, particularly in fields like energy planning that face great uncertainty and rapidly transforming contexts. Building on the work of the Stockholm Resilience Centre, this paper begins by outlining...... the relationship between resilience and energy planning, suggesting that planning in, and with, time is a core necessity in this domain. It then reviews four examples of graphically mapping with time, highlighting some of the key challenges, before tentatively proposing a graphical language to be employed...... by planners when aiming to construct resilient energy plans. It concludes that a graphical language has the potential to be a significant tool, flexibly facilitating cross-disciplinary communication and decision-making, while emphasising that its role is to support imaginative, resilient planning rather than...
Lascu, Dan
2014-01-01
We consider a family {τ m : m ≥ 2} of interval maps which are generalizations of the Gauss transformation. For the continued fraction expansion arising from τ m , we solve a Gauss-Kuzmin-type problem.
Modeling of GPS tropospheric delay wet Neill mapping function (NMF)
Sakidin, Hamzah; Ahmad, Asmala; Bugis, Ismadi
2014-10-01
The modeling of the GPS tropospheric delay mapping function should be revised by modifying or simplify its mathematical model. Some current mapping functions models are separated into hydrostatic and the wet part. The current tropospheric delay models use mapping functions in the form of continued fractions. This model is quite complex and need to be simplified. By using regression method, the wet mapping function models has been selected to be simplified. There are eleven operations for wet mapping function component of Neill Mapping Function (NMF), to be carried out before getting the mapping function scale factor. So, there is a need to simplify the mapping function models to allow faster calculation and also better understanding of the models.
Modeling nuclear volume isotope effects in crystals
Schauble, Edwin A.
2013-01-01
Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac–Hartree–Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor–crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium
Modeling nuclear volume isotope effects in crystals.
Schauble, Edwin A
2013-10-29
Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from (119)Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium.
REFractions: The Representing Equivalent Fractions Game
Tucker, Stephen I.
2014-01-01
Stephen Tucker presents a fractions game that addresses a range of fraction concepts including equivalence and computation. The REFractions game also improves students' fluency with representing, comparing and adding fractions.
Directory of Open Access Journals (Sweden)
L. Sabo Boschi
2012-09-01
submerged aquatic plants is a complex task due to the difficulty in volumetrically mapping and quantifying the colonized areas. In these cases, the use of hydro-acoustic data allows mapping and measuring these areas, helping formulate proposals for sustainable management of this type of aquatic vegetation. This study used the kriging technique and acoustic data to perform the spatial inference of the biovolume of submerged aquatic plants. The data was obtained from three echobathimetric surveys conducted in a Paraná River study area, characterized by the proliferation of submerged aquatic vegetation, hindering navigation. High spatial resolution multi-spectral imagery World View-2 was used to delimit the areas with submerged aquatic plants. The mapping of the bio-volume of submerged aquatic plants was conducted through the bio-volume inference using the Kriging technique and slicing of the inferred values at 15% intervals. The map generated allowed identifying the areas of highest concentration of submerged macrophytes, which predominantly presented bio-volume values between 15-30% and 30-45%. This confirms the feasibility of using the kriging technique for biovolume spatial inference through geo-referenced ecobathimetric measurements and the support of high spatial resolution imagery.
Fractional active disturbance rejection control.
Li, Dazi; Ding, Pan; Gao, Zhiqiang
2016-05-01
A fractional active disturbance rejection control (FADRC) scheme is proposed to improve the performance of commensurate linear fractional order systems (FOS) and the robust analysis shows that the controller is also applicable to incommensurate linear FOS control. In FADRC, the traditional extended states observer (ESO) is generalized to a fractional order extended states observer (FESO) by using the fractional calculus, and the tracking differentiator plus nonlinear state error feedback are replaced by a fractional proportional-derivative controller. To simplify controller tuning, the linear bandwidth-parameterization method has been adopted. The impacts of the observer bandwidth ωo and controller bandwidth ωc on system performance are then analyzed. Finally, the FADRC stability and frequency-domain characteristics for linear single-input single-output FOS are analyzed. Simulation results by FADRC and ADRC on typical FOS are compared to demonstrate the superiority and effectiveness of the proposed scheme. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
Topology of singular fibers of differentiable maps
Saeki, Osamu
2004-01-01
The volume develops a thorough theory of singular fibers of generic differentiable maps. This is the first work that establishes the foundational framework of the global study of singular differentiable maps of negative codimension from the viewpoint of differential topology. The book contains not only a general theory, but also some explicit examples together with a number of very concrete applications. This is a very interesting subject in differential topology, since it shows a beautiful interplay between the usual theory of singularities of differentiable maps and the geometric topology of manifolds.
Mapping strategy, structure, ownership and performance in European corporations : Introduction
Colli, A.; Iversen, M.J.; de Jong, A.
2011-01-01
This paper is the introduction to the Business History special issue on European Business Models. The volume presents results of the international project about mapping European corporations, within the strategy, structure, ownership and performance (SSOP) framework. The paper describes the
Global asymptotical ω-periodicity of a fractional-order non-autonomous neural networks.
Chen, Boshan; Chen, Jiejie
2015-08-01
We study the global asymptotic ω-periodicity for a fractional-order non-autonomous neural networks. Firstly, based on the Caputo fractional-order derivative it is shown that ω-periodic or autonomous fractional-order neural networks cannot generate exactly ω-periodic signals. Next, by using the contraction mapping principle we discuss the existence and uniqueness of S-asymptotically ω-periodic solution for a class of fractional-order non-autonomous neural networks. Then by using a fractional-order differential and integral inequality technique, we study global Mittag-Leffler stability and global asymptotical periodicity of the fractional-order non-autonomous neural networks, which shows that all paths of the networks, starting from arbitrary points and responding to persistent, nonconstant ω-periodic external inputs, asymptotically converge to the same nonconstant ω-periodic function that may be not a solution. Copyright © 2015 Elsevier Ltd. All rights reserved.
Semi-infinite fractional programming
Verma, Ram U
2017-01-01
This book presents a smooth and unified transitional framework from generalised fractional programming, with a finite number of variables and a finite number of constraints, to semi-infinite fractional programming, where a number of variables are finite but with infinite constraints. It focuses on empowering graduate students, faculty and other research enthusiasts to pursue more accelerated research advances with significant interdisciplinary applications without borders. In terms of developing general frameworks for theoretical foundations and real-world applications, it discusses a number of new classes of generalised second-order invex functions and second-order univex functions, new sets of second-order necessary optimality conditions, second-order sufficient optimality conditions, and second-order duality models for establishing numerous duality theorems for discrete minmax (or maxmin) semi-infinite fractional programming problems. In the current interdisciplinary supercomputer-oriented research envi...
1981-01-19
Computer Mapping in Geoecology , The Harvard Library of Computer Graphics, 1979 Mapping Collection, Vol. 5, pp 11-27. 5. Robinson, A.H. (1974) A New Map...Use of Synagraphic Computer Mapping in Geoecology , The Harvard Library of Computer Graphics, 1979 Mapping Collection, Vol. 5, pp 11-27. 5. Robinson, A
Glass, Tom
2016-01-01
When students generate mind maps, or concept maps, the maps are usually on paper, computer screens, or a blackboard. Human Mind Maps require few resources and little preparation. The main requirements are space where students can move around and a little creativity and imagination. Mind maps can be used for a variety of purposes, and Human Mind…
Liu, Dan; Borlotti, Alessandra; Viliani, Dafne; Jerosch-Herold, Michael; Alkhalil, Mohammad; De Maria, Giovanni Luigi; Fahrni, Gregor; Dawkins, Sam; Wijesurendra, Rohan; Francis, Jane; Ferreira, Vanessa; Piechnik, Stefan; Robson, Matthew D.; Banning, Adrian; Choudhury, Robin; Neubauer, Stefan; Channon, Keith; Kharbanda, Rajesh
2017-01-01
Background— CMR T1 mapping is a quantitative imaging technique allowing the assessment of myocardial injury early after ST-segment–elevation myocardial infarction. We sought to investigate the ability of acute native T1 mapping to differentiate reversible and irreversible myocardial injury and its predictive value for left ventricular remodeling. Methods and Results— Sixty ST-segment–elevation myocardial infarction patients underwent acute and 6-month 3T CMR, including cine, T2-weighted (T2W) imaging, native shortened modified look-locker inversion recovery T1 mapping, rest first pass perfusion, and late gadolinium enhancement. T1 cutoff values for oedematous versus necrotic myocardium were identified as 1251 ms and 1400 ms, respectively, with prediction accuracy of 96.7% (95% confidence interval, 82.8% to 99.9%). Using the proposed threshold of 1400 ms, the volume of irreversibly damaged tissue was in good agreement with the 6-month late gadolinium enhancement volume (r=0.99) and correlated strongly with the log area under the curve troponin (r=0.80) and strongly with 6-month ejection fraction (r=−0.73). Acute T1 values were a strong predictor of 6-month wall thickening compared with late gadolinium enhancement. Conclusions— Acute native shortened modified look-locker inversion recovery T1 mapping differentiates reversible and irreversible myocardial injury, and it is a strong predictor of left ventricular remodeling in ST-segment–elevation myocardial infarction. A single CMR acquisition of native T1 mapping could potentially represent a fast, safe, and accurate method for early stratification of acute patients in need of more aggressive treatment. Further confirmatory studies will be needed. PMID:28798137
On a Fractional Master Equation
Directory of Open Access Journals (Sweden)
Anitha Thomas
2011-01-01
derivative and Caputo derivative of order ,,1<ℜ(≤2 and 1<ℜ(≤2 respectively. In this paper, we derive an analytic solution for the fractional time-independent form of the wave equation or diffusion equation in two dimensions in terms of the Mittag-Leffler function. The solutions to the fractional Poisson and the Laplace equations of the same kind are obtained, again represented by means of the Mittag-Leffler function. In all three cases, the solutions are represented also in terms of Fox's -function.
On a fractional difference operator
Directory of Open Access Journals (Sweden)
P. Baliarsingh
2016-06-01
Full Text Available In the present article, a set of new difference sequence spaces of fractional order has been introduced and subsequently, an application of these spaces, the notion of the derivatives and the integrals of a function to the case of non-integer order have been generalized. Certain results involving the unusual and non-uniform behavior of the corresponding difference operator have been investigated and also been verified by using some counter examples. We also verify these unusual and non-uniform behaviors by studying the geometry of fractional calculus.
Long memory and tail dependence in trading volume and volatility
DEFF Research Database (Denmark)
Rossi, Eduardo; Santucci de Magistris, Paolo
2013-01-01
We investigate the relationship between volatility, measured by realized volatility, and trading volume for 25 NYSE stocks. We show that volume and volatility are long memory but not fractionally cointegrated in most cases. We also find right tail dependence in the volatility and volume innovations......, say long memory, marginal non-normality and tail dependence. A simulation and forecasting exercise highlight the importance of modeling both long memory and tail dependence to capture extreme events....
Hong, Yoo Jin; Kim, Tai Kyung; Hong, Donghyun; Park, Chul Hwan; Yoo, Sae Jong; Wickum, Mary Ellen; Hur, Jin; Lee, Hye-Jeong; Kim, Young Jin; Suh, Young Joo; Greiser, Andreas; Paek, Mun Young; Choi, Byoung Wook
2016-07-01
This study sought to evaluate whether patterns of myocardial change in doxorubicin-induced dilated cardiomyopathy determined using dual-energy computed tomography (CT) were similar to characterization by extracellular volume fraction (ECV) using cardiac magnetic resonance (CMR) T1-mapping and collagen volume fraction (CVF) measured using histology. Anthracycline chemoagents are effective against a wide range of malignant conditions. However, cardiotoxicity is a well-known adverse effect of these drugs. Dual-energy CT could be as useful as magnetic resonance (MR) to evaluate myocardial change in anthracycline-induced cardiotoxicity. A dilated cardiomyopathy rabbit model was generated by injecting 11 adult New Zealand rabbits with 1.0 mg/kg of doxorubicin twice weekly for 16 weeks. Contrast-enhanced dual-energy CT and pre-contrast and post-contrast T1-mapping CMR using a prototype modified Look-Locker inversion recovery on a clinical 3-T scanner were performed on 15 rabbits, including 4 control animals, to calculate ECV at baseline, and at 6, 12, and 16 weeks after doxorubicin administration. The mean ECV values (%) on CT and CMR at 6, 12, and 16 weeks after modeling were significantly higher than those measured at baseline (CT ECV: 35.3%, 41.9%, 42.1% vs. 28.5%; MR ECV: 32.6%, 35.8%, 41.3% vs. 28.8%, respectively; all p histology (CT ECV vs. CVF, r = 0.925, p histology. Dual-energy CT is useful for characterizing doxorubicin-induced cardiomyopathy by measuring ECV fraction; however, further technical improvements are desirable to lower motion artifact and improve image quality of the iodine map. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Fractional Processes and Fractional-Order Signal Processing Techniques and Applications
Sheng, Hu; Qiu, TianShuang
2012-01-01
Fractional processes are widely found in science, technology and engineering systems. In Fractional Processes and Fractional-order Signal Processing, some complex random signals, characterized by the presence of a heavy-tailed distribution or non-negligible dependence between distant observations (local and long memory), are introduced and examined from the ‘fractional’ perspective using simulation, fractional-order modeling and filtering and realization of fractional-order systems. These fractional-order signal processing (FOSP) techniques are based on fractional calculus, the fractional Fourier transform and fractional lower-order moments. Fractional Processes and Fractional-order Signal Processing: • presents fractional processes of fixed, variable and distributed order studied as the output of fractional-order differential systems; • introduces FOSP techniques and the fractional signals and fractional systems point of view; • details real-world-application examples of FOSP techniques to demonstr...
Phani, M Kalyan; Kumar, Anish; Jayakumar, T; Samwer, Konrad
2015-01-01
Summary The distribution of elastic stiffness and damping of individual phases in an α + β titanium alloy (Ti-6Al-4V) measured by using atomic force acoustic microscopy (AFAM) is reported in the present study. The real and imaginary parts of the contact stiffness k * are obtained from the contact-resonance spectra and by using these two quantities, the maps of local elastic stiffness and the damping factor are derived. The evaluation of the data is based on the mass distribution of the cantilever with damped flexural modes. The cantilever dynamics model considering damping, which was proposed recently, has been used for mapping of indentation modulus and damping of different phases in a metallic structural material. The study indicated that in a Ti-6Al-4V alloy the metastable β phase has the minimum modulus and the maximum damping followed by α′- and α-phases. Volume fractions of the individual phases were determined by using a commercial material property evaluation software and were validated by using X-ray diffraction (XRD) and electron back-scatter diffraction (EBSD) studies on one of the heat-treated samples. The volume fractions of the phases and the modulus measured through AFAM are used to derive average modulus of the bulk sample which is correlated with the bulk elastic properties obtained by ultrasonic velocity measurements. The average modulus of the specimens estimated by AFAM technique is found to be within 5% of that obtained by ultrasonic velocity measurements. The effect of heat treatments on the ultrasonic attenuation in the bulk sample could also be understood based on the damping measurements on individual phases using AFAM. PMID:25977847
Directory of Open Access Journals (Sweden)
S. I. Pérez-Elvira
Full Text Available Abstract The fractioning into separate liquid and solid fractions obtained by centrifugation of thickened fresh and thermally pretreated (170 ºC, 50 minutes secondary sludge showed that 30% of the particulate organic matter was released during the pretreatment, correspondingly increasing the methane production of the particulate matter by 30% (from 259 to 329 mL CH4/g VSfed. The responsible of this enhancement was the liquid fraction, as the biodegradability of the solid fraction remained constant after the pretreatment. Mass balances showed that 34% of the VS were released to the liquid fraction, generating nearly 50% of the total methane produced, with much faster kinetics compared to the solid fraction. These results support the hypothesis of a separate liquid-solid digestion of thermally pretreated sludge, which would result in decreasing the digestion volume to half while duplicating the methane productivity per kilogram of sludge fed to digestion.