WorldWideScience

Sample records for axial tomography evidence

  1. Computer axial tomography in geosciences

    International Nuclear Information System (INIS)

    Computer Axial Tomography (CAT) is one of the most adequate non-invasive techniques for the investigation of the internal structure of a large category of objects. Initially designed for medical investigations, this technique, based on the attenuation of X- or gamma-ray (and in some cases neutrons), generates digital images which map the numerical values of the linear attenuation coefficient of a section or of the entire volume of the investigated sample. Shortly after its application in medicine, CAT has been successfully used in archaeology, life sciences, and geosciences as well as for the industrial materials non-destructive testing. Depending on the energy of the utilized radiation as well as on the effective atomic number of the sample, CAT can provide with a spatial resolution of 0.01 - 0.5 mm, quantitative as well as qualitative information concerning local density, porosity or chemical composition of the sample. At present two types of axial Computer Tomographs (CT) are in use. One category, consisting of medical as well as industrial CT is equipped with X-ray tubes while the other uses isotopic gamma-ray sources. CT provided with intense X-ray sources (equivalent to 12-15 kCi or 450-550 TBq) has the advantage of an extremely short running time (a few seconds and even less) but presents some disadvantages known as beam hardening and absorption edge effects. These effects, intrinsically related to the polychromatic nature of the X-rays generated by classical tubes, need special mathematical or physical corrections. A polychromatic X-ray beam can be made almost monochromatic by means of crystal diffraction or by using adequate multicomponent filters, but these devices are costly and considerably diminish the output of X-ray generators. In the case of CT of the second type, monochromatic gamma-rays generated by radioisotopic sources, such as 169 Yb (50.4 keV), 241 Am (59 keV), 192 Ir (310.5 and 469.1 keV ) or 137 Cs (662.7 keV), are used in combination with

  2. Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to demonstrate key elements of feasibility for a high speed automated time domain terahertz computed axial tomography (TD-THz CT) non destructive...

  3. Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Phase 2 project, we propose to develop, construct, and deliver to NASA a computed axial tomography time-domain terahertz (CT TD-THz) non destructive...

  4. Computerized axial tomography : the tool in osseointegrated dental implants

    International Nuclear Information System (INIS)

    Failure rates in rehabilitations with osseointegrated implants are handled through appropriate radiographic preoperative planning. The appropriate length of the implant without running the risk of a perforation of vital structures, has been determined by a radiographic diagnosis. Computerized and conventional axial tomography have proved to be invaluable elements for pre-surgical evaluation. A radiologic guidance is elaborated to perform a computerized axial tomography (CT) of maxillary bones in totally edentulous patients. Surgical guides are constructed from a wax-up emanated from the information of the CT. The CT has proven to be an radiographic indispensable element to achieve the surgical-prosthetic success in osseointegrated dental implants. The CT has allowed the realization of a precise wax-up for making of surgical guide and a precise temporary prostheses in positioning of osseointegrated implants, with the consequent saving time and money for the rehabilitator and patient

  5. Axial myopia in computed and magnetic resonance tomography

    International Nuclear Information System (INIS)

    The case of a 44-year old woman suffering from amblyopia on the left eye with unilateral proptosis caused by axial (progressive) myopia is presented. The clinical and radiological findings were discussed in reference to the literature. The diagnosis was established by ruling out neoplastic, inflammatory or endocrine causes for the exophtalmos. CT and MR scans revealed an enlarged left globe without evidence of orbital masses. The findings were regarded as typical for the diagnosis at axial myopia. (orig.)

  6. Axial myopia in computed and magnetic resonance tomography

    Energy Technology Data Exchange (ETDEWEB)

    Beyer-Enke, S.A.; Goerich, J.; Gamroth, A.

    1987-08-01

    The case of a 44-year old woman suffering from amblyopia on the left eye with unilateral proptosis caused by axial (progressive) myopia is presented. The clinical and radiological findings were discussed in reference to the literature. The diagnosis was established by ruling out neoplastic, inflammatory or endocrine causes for the exophtalmos. CT and MR scans revealed an enlarged left globe without evidence of orbital masses. The findings were regarded as typical for the diagnosis at axial myopia.

  7. Axial positrons emission tomography: from mouse to human brain imaging

    International Nuclear Information System (INIS)

    Positrons emission tomography is a nuclear imaging technics using nuclear decays. It is used both in clinical and preclinical studies. The later requires the use of small animals such as the mouse. The objective is to obtain the best signal with the best spatial resolution. Yet, a weight ratio between humans and mice indicates the need of a sub-millimeter resolution. A conventional scanner is based on detection modules surrounding the object to image and arranged perpendicularly. This implies a strong relationship between efficiency and spatial resolution. This work focuses on the axial geometry in which detection modules are arranged parallel to the object. This limits the relationship between the figures of merit, leading to both high spatial resolution and efficiency. The simulations of prototypes showed great perspectives in term of sub-millimeter resolution with efficiencies of 15 or 40% according to the scanner's axial extension. These results indicate great perspectives for both clinical and preclinical imaging. (author)

  8. A review of X-ray computed axial tomography

    International Nuclear Information System (INIS)

    A review of Computed axial tomography (CAT) scanning literature outlining the theoretical and practical aspects of this technique with application in both medical diagnosis and industrial non-destructive inspection (NDI) is presented. Practical aspects of CAT scanning discussed include : radiation sources, currently available spatial and contrast resolution limits and the evolution of the computerized tomography (CT) system. It was found that monochromatic gamma rays are preferred to X-rays, especially for very high density materials, and that in medical CAT scanning, the special resolution is only, 0.5 mm while spatial resolutions of less than 50μm have been achieved in NDI. An increased number of scientific and industrial applications are anticipated (e.g. for studying sintering reactions), as the capital cost of CAT scanning decreased. 13 refs., 9 figs., 2 tabs

  9. Computerized axial tomography in the detection of brain damage

    International Nuclear Information System (INIS)

    The cranial computerized axial tomography (CAT) findings in groups of patients with epilepsy, migraine, hypertension, and other general medical disorders have been reviewed to assess the frequency and patterns of focal and diffuse brain damage. In addition to demonstrating focal lesions in a proportion of patients with seizures and in patients presenting with a stroke, the CAT scan showed a premature degree of cerebral atrophy in an appreciable proportion of patients with long-standing epilepsy, hypertension and diabetes, and in some patients with migraine, valvular and ischaemic heart disease, chronic obstructive airways disease, and chronic renal failure. The value of CAT as a means of screening for brain damage in groups of individuals at risk is discussed

  10. Contribution of conventional axial computed tomography (nonhelical), in conjunction with panoramic tomography (zonography), in evaluating mandibular fractures.

    Science.gov (United States)

    Wilson, I F; Lokeh, A; Benjamin, C I; Hilger, P A; Hamlar, D D; Ondrey, F G; Tashjian, J H; Thomas, W; Schubert, W

    2000-10-01

    Previous studies comparing the sensitivity between different radiological exams have concluded that conventional axial computed tomography (CT; nonhelical) is unsuitable in the assessment of mandibular fractures. Axial CT was shown to have a reduced sensitivity compared with plain radiographs and panoramic tomography because it missed nondisplaced fractures in the posterior portion of the mandible. Because the resolution of CT has improved from the time of these previous studies, the authors were interested in assessing whether axial CT (nonhelical) could now provide additional clinically useful information and enhance our understanding of mandibular fractures, beyond that obtained from panoramic tomography alone. In their study, 5 staff surgeons initially evaluated the panoramic tomograms and then the CT scans of 39 patients with 66 fractures. A series of four questions assessed the relative contribution of these two radiological exams in formulating an optimal operative plan for each patient. The authors found that axial CT provided supplementary information regarding missed fractures, comminution, and the exact size and degree of displacement of fracture fragments. This additional data could have changed the operative plan in a substantial proportion of patients (17 of 39). Axial CT demonstrated two missed parasymphyseal fractures (2 of 39 patients) that were not seen on these patients' panoramic tomograms. Axial CT also revealed undiscovered comminution or demonstrated fracture displacement more precisely in 39% of patients (15 of 39) and 24% of fractures (16 of 66). This study demonstrates that axial CT was clinically useful as an additional investigation to panoramic tomography. Axial CT helped elucidate further the nature of suspected mandibular fractures. PMID:11037164

  11. Development of Axial Tomography for Steam Explosion Study

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Young; Seo, Shi Won [HanDong Global University, Pohang (Korea, Republic of); Song, Jin Ho [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2006-07-01

    Visual understanding of complicated system leads us often to the intuitive enlightenment of the invisible causes of the effect. When it is formulated based on the rigorous mathematics, the produced formula or correlation will be very useful in design and analysis of the engineering system. In this point of view, the tomography technology can be a tool to meet such a purpose. However, the traditional hard ray tomography using high energy radiation cannot meet the case due to heavy shielding structure which obstructs access of the sensing unit to the very complicated and limited space. Therefore, the recent development of the electric tomography is noteworthy in the application to the industrial process monitoring. It has the merit not only of low cost but also of easier access to the limited space than the hard ray tomography.

  12. Investigations of the radiation exposure of the head during computerized axial tomography

    International Nuclear Information System (INIS)

    Various head phantoms and patients were used to measure, by means of thermoluminescence and film dosimetry, the radiation exposure of the head, especially of the eye lenses, in computerized axial tomography with the EMI scanner. The form of the isodoses and the dependence on position of the exposure dose in the region of the eyes were confirmed by calculations with a computer program. (orig.)

  13. Comparison of Computed Tomography Scout Based Reference Point Localization to Conventional Film and Axial Computed Tomography

    International Nuclear Information System (INIS)

    Identification of source positions after implantation is an important step in brachytherapy planning. Reconstruction is traditionally performed from films taken by conventional simulators, but these are gradually being replaced in the clinic by computed tomography (CT) simulators. The present study explored the use of a scout image–based reconstruction algorithm that replaces the use of traditional film, while exhibiting low sensitivity to metal-induced artifacts that can appear in 3D CT methods. In addition, the accuracy of an in-house graphical software implementation of scout-based reconstruction was compared with seed location reconstructions for 2 phantoms by conventional simulator and CT measurements. One phantom was constructed using a planar fixed grid of 1.5-mm diameter ball bearings (BBs) with 40-mm spacing. The second was a Fletcher-Suit applicator embedded in Styrofoam (Dow Chemical Co., Midland, MI) with one 3.2-mm-diameter BB inserted into each of 6 surrounding holes. Conventional simulator, kilovoltage CT (kVCT), megavoltage CT, and scout-based methods were evaluated by their ability to calculate the distance between seeds (40 mm for the fixed grid, 30–120 mm in Fletcher-Suit). All methods were able to reconstruct the fixed grid distances with an average deviation of <1%. The worst single deviations (approximately 6%) were exhibited in the 2 volumetric CT methods. In the Fletcher-Suit phantom, the intermodality agreement was within approximately 3%, with the conventional sim measuring marginally larger distances, with kVCT the smallest. All of the established reconstruction methods exhibited similar abilities to detect the distances between BBs. The 3D CT-based methods, with lower axial resolution, showed more variation, particularly with the smaller BBs. With a software implementation, scout-based reconstruction is an appealing approach because it simplifies data acquisition over film-based reconstruction without requiring any specialized

  14. Time-Domain Terahertz Computed Axial Tomography NDE System

    Science.gov (United States)

    Zimdars, David

    2012-01-01

    NASA has identified the need for advanced non-destructive evaluation (NDE) methods to characterize aging and durability in aircraft materials to improve the safety of the nation's airline fleet. 3D THz tomography can play a major role in detection and characterization of flaws and degradation in aircraft materials, including Kevlar-based composites and Kevlar and Zylon fabric covers for soft-shell fan containment where aging and durability issues are critical. A prototype computed tomography (CT) time-domain (TD) THz imaging system has been used to generate 3D images of several test objects including a TUFI tile (a thermal protection system tile used on the Space Shuttle and possibly the Orion or similar capsules). This TUFI tile had simulated impact damage that was located and the depth of damage determined. The CT motion control gan try was designed and constructed, and then integrated with a T-Ray 4000 control unit and motion controller to create a complete CT TD-THz imaging system prototype. A data collection software script was developed that takes multiple z-axis slices in sequence and saves the data for batch processing. The data collection software was integrated with the ability to batch process the slice data with the CT TD-THz image reconstruction software. The time required to take a single CT slice was decreased from six minutes to approximately one minute by replacing the 320 ps, 100-Hz waveform acquisition system with an 80 ps, 1,000-Hz waveform acquisition system. The TD-THZ computed tomography system was built from pre-existing commercial off-the-shelf subsystems. A CT motion control gantry was constructed from COTS components that can handle larger samples. The motion control gantry allows inspection of sample sizes of up to approximately one cubic foot (.0.03 cubic meters). The system reduced to practice a CT-TDTHz system incorporating a COTS 80- ps/l-kHz waveform scanner. The incorporation of this scanner in the system allows acquisition of 3D

  15. Measurement of tibial torsion by axial computerized tomography

    International Nuclear Information System (INIS)

    The results of measurement of abnormal tibial torsion by computerized tomography are described. The technique allows precise measurement of tibial torsion and is easier than conventional clinical and radiological methods. Tibial torsion was found to be symmetrical in the small group of patients in this series, and there was considerable variation between individuals. In 17 patients (age range: 12-82 years) the tibial torsion was 28.80 +- 13.40 (mean +-2 SD). An extremely abnormal bilateral rachitic tibial torsion of 580 was found in a 17 year old female. Tibial torsion was measured in 6 patients with fractures of the lower leg; there were no significant differences between the injured and uninjured sides in 3 patients, but in the 3 remaining patients the fractured legs showed significantly decreased torsion caused by internal rotation deformity. (orig.)

  16. A study of the imaging of atomic elements by computerised axial tomography

    OpenAIRE

    McCarthy, K J

    1989-01-01

    Conventional computerized axial tomography images show the spatial variation in the linear attenuation coefficient in a cross-section of a specimen. However, no information is present to enable one to predict the location nor concentration of an atomic element in the image. Differential X-ray absorptiometry is a well established analytic technique for determining the concentration of an atomic element in a specimen. In this thesis, it is shown that by applying differential X-ray absorpt...

  17. Analysis and calibration of stage axial vibration for synchrotron radiation nanoscale computed tomography.

    Science.gov (United States)

    Fu, Jian; Li, Chen; Liu, Zhenzhong

    2015-10-01

    Synchrotron radiation nanoscale computed tomography (SR nano-CT) is a powerful analysis tool and can be used to perform chemical identification, mapping, or speciation of carbon and other elements together with X-ray fluorescence and X-ray absorption near edge structure (XANES) imaging. In practical applications, there are often challenges for SR nano-CT due to the misaligned geometry caused by the sample stage axial vibration. It occurs quite frequently because of experimental constraints from the mechanical error of manufacturing and assembly and the thermal expansion during the time-consuming scanning. The axial vibration will lead to the structure overlap among neighboring layers and degrade imaging results by imposing artifacts into the nano-CT images. It becomes worse for samples with complicated axial structure. In this work, we analyze the influence of axial vibration on nano-CT image by partial derivative. Then, an axial vibration calibration method for SR nano-CT is developed and investigated. It is based on the cross correlation of plane integral curves of the sample at different view angles. This work comprises a numerical study of the method and its experimental verification using a dataset measured with the full-field transmission X-ray microscope nano-CT setup at the beamline 4W1A of the Beijing Synchrotron Radiation Facility. The results demonstrate that the presented method can handle the stage axial vibration. It can work for random axial vibration and needs neither calibration phantom nor additional calibration scanning. It will be helpful for the development and application of synchrotron radiation nano-CT systems. PMID:26265032

  18. Dose profile measurement in computerized axial tomography equipment using thermoluminescent dosemeters; Medicion del perfil de dosis en equipos de tomografia axial computarizada usando dosimetros termoluminiscentes

    Energy Technology Data Exchange (ETDEWEB)

    Azorin V, J.C.; Falcony, C.; Azorin N, J. [Centro de Investigacion en Ciencia y Tecnologia Avanzada, IPN, 07000 Mexico D.F. (Mexico)

    2000-07-01

    In this work are presented the results about measuring the radiation dose profile in two equipment of computerized axial tomography (Tac). Thermoluminescent dosemeters (Dtl) of LiF, Mg, Cu, P + Ptfe in form of disks were used which were developed and made in Mexico. The results showed that Dtl are appropriated for these type of studies. (Author)

  19. Study of the human encephalon morphology by computerized axial tomography in neurological diseases

    International Nuclear Information System (INIS)

    Since the middle of the last century, the study of the human encephalon morphology has been of great interest for the researchers. With the introduction of the computerized axial tomography in 1974, it was possible to expand the knowledge about this area and at the same time provide information on the structural lesions that are pathologies of great psychosocial repercussion like epilepsy and Parkinsonism. This paper used 90 tomographic studies on people aged 20-80 years. A series of linear measurements were made and statistically processed. The results showed variations in linear measurements among control, epileptic and Parkinsonian subjects

  20. X-ray detectors in axial computed tomography development; Sensori di radiazioni X negli sviluppi della tomografia assiale computerizzata

    Energy Technology Data Exchange (ETDEWEB)

    Gislon, R.; Imperiali, F. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dip. Innovazione

    1996-12-01

    The increase of potentially of axial computed tomography as a non destructive investigation method in industrial field is particularly tied to the development of the X-rays detectors. The transition from the first gas ionization detectors to the last semiconductor detectors has indeed dramatically increased the performances of tomographic systems. In this report, after a quick analysis of fundamental principles of tomography, the most significant parameters for a detector to be used in a tomographic system are reviewed. The examination of the principal kinds of detectors that have been up to now used, with their working schemes, allows to delineate their characteristics and so to compare them with the ideal detector sketched above. The necessity of using high definition arrays brings to put into evidence the inadequacy of both gas and liquid ionization detectors and also of those types of light conversion devices which utilize for signal amplification a photomultiplier tube. Systems based on charge coupled devices or on a light conversion obtained with semiconductor photodiode arrays are definitely to be preferred. The progress of the last years in microelectronic technologies has brought great improvements in this field.

  1. Value of the computerized axial tomography for early diagnosis of cranio cerebral trauma

    International Nuclear Information System (INIS)

    A descriptive and cross-sectional study was conducted in 62 patients with cranio cerebral trauma admitted to 'Saturnino Lora' Provincial Teaching Hospital of Santiago de Cuba, from January 2005 to May 2006, in whom computerized axial tomography indicated at the emergency room was performed with the purpose of evaluating the effectiveness of this radiographic technique for early diagnosis of the injury. In the case material there was neither association between the source and imaging results, nor between the age and sex. The main clinical manifestations were vomiting, headache and motor deficit as well as frontal location, intraparenchymatous hematoma (the latter as the most common image finding) and the hyperdense area as tomographic pattern. The survival was of 91,9%

  2. Computerized axial tomography of the chest for visualization of ''absent'' pulmonary arteries

    International Nuclear Information System (INIS)

    To expand the search for central pulmonary arteries in six patients with absence of cardiac-pulmonary continuity, computerized axial tomography (CAT) of the chest was performed. The CAT scans were compared with previous arteriograms and pulmonary vein wedge angiograms. Three patients with type IV truncus arteriosus were studied, and none had a central, right or left pulmonary artery on CAT scan. However, two patients with tetralogy of Fallot with pulmonary atresia and a patent ductus arteriosus to the right lung demonstrated the presence of a left pulmonary artery. In addition, one child with truncus arteriosus with ''absent'' left pulmonary artery demonstrated a left pulmonary artery on the CAT scan. The CAT scan may therefore enhance our ability to search for disconnected pulmonary arteries in children with complex cyanotic congenital heart disease

  3. Spectral estimation optical coherence tomography for axial super-resolution (Conference Presentation)

    Science.gov (United States)

    Liu, Xinyu; Yu, Xiaojun; Wang, Nanshuo; Bo, En; Luo, Yuemei; Chen, Si; Cui, Dongyao; Liu, Linbo

    2016-03-01

    The sample depth reflectivity profile of Fourier domain optical coherence tomography (FD-OCT) is estimated from the inverse Fourier transform of the spectral interference signals (interferograms). As a result, the axial resolution is fundamentally limited by the coherence length of the light source. We demonstrate an axial resolution improvement method by using the autoregressive spectral estimation technique to instead of the inverse Fourier transform to analyze the spectral interferograms, which is named as spectral estimation OCT (SE-OCT). SE-OCT improves the axial resolution by a factor of up to 4.7 compared with the corresponding FD-OCT. Furthermore, SE-OCT provides a complete sidelobe suppression in the point-spread function. Using phantoms such as an air wedge and micro particles, we prove the ability of resolution improvement. To test SE-OCT for real biological tissue, we image the rat cornea and demonstrate that SE-OCT enables clear identification of corneal endothelium anatomical details ex vivo. We also find that the performance of SE-OCT is depended on SNR of the feature object. To evaluate the potential usage and define the application scope of SE-OCT, we further investigate the property of SNR dependence and the artifacts that may be caused. We find SE-OCT may be uniquely suited for viewing high SNR layer structures, such as the epithelium and endothelium in cornea, retina and aorta. Given that SE-OCT can be implemented in the FD-OCT devices easily, the new capabilities provided by SE-OCT are likely to offer immediate improvements to the diagnosis and management of diseases based on OCT imaging.

  4. Geneva University - The AX-PET experiment : A demonstrator for an axial Positron Emission Tomography

    CERN Multimedia

    Université de Genève

    2012-01-01

    Geneva University École de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92   Wednesday 14 March 2012 SEMINAIRE DE PHYSIQUE CORPUSCULAIRE 11.15 a.m. - Science II, Auditoire 1S081, 30, quai Ernest-Ansermet, 1211 Genève 4 The AX-PET experiment : A demonstrator for an axial Positron Emission Tomography Dr Chiara CASELLA   ETH Zurich   PET (Positron Emission Tomography) is a tool for in-vivo functional imaging, successfully used since the earliest days of nuclear medicine. It is based on the detection of the two coincident 511 keV photons from the annihilation of a positron, emitted from a radiotracer injected into the body. Tomographic analysis of the coincidence data allows for a 3D reconstructed image of the source distribution. The AX-PET experiment proposes a novel geometrical approach for a PET scanner, in which l...

  5. Measurements of computed tomography dose index for axial and spiral CT scanners

    International Nuclear Information System (INIS)

    The energy deposited in the patient by the rotating x-ray beam in computed tomography produces more uniform absorbed dose values within the section of imaged tissue than those produced in conventional radiological procedures. The dose values within a specific section are determined by factors such as voltage, current, scan field, rotation angle, filtration, collimation, and section thickness and spacing. This study is a part of extensive project, aiming to investigate practice of computed tomography at various hospitals and to implement a Reference Dose Levels (RDLs) to routine CT examinations in Egypt. The dosimetric quantities proposed in the European Guidelines (EG) for CT are weighted computed tomography dose index (CTDIw) for a single slice and dose-length product (DLP) for a complete examination. Patient-related data as well as technical parameters for head, chest, abdomen and pelvis examinations were collected for seven CT scanners in public and private hospitals.Dose measurements were performed for both axial and spiral models for a range of CT examinations using CT dosimetry head and body phantoms, and ion chamber designed for CT dosimetry. The determined CTDIw and DLP values were compared with the European Commission reference dose levels (ECRDLs) and also with some international survey results. Mean values of CTDIw had a range of 36-69 m Gy with average 55 m Gy for head, and 11-35 mGy with average 23 mGy for chest, abdomen and pelvis examinations. The current reference CTDIw values are 60 m Gy for adult head and 25 m Gy for adult Abdomen

  6. Seeing the Axial Line: Evidence from Wayfinding Experiments

    Directory of Open Access Journals (Sweden)

    Beatrix Emo

    2014-07-01

    Full Text Available Space-geometric measures are proposed to explain the location of fixations during wayfinding. Results from an eye tracking study based on real-world stimuli are analysed; the gaze bias shows that attention is paid to structural elements in the built environment. Three space-geometric measures are used to explain the data: sky area, floor area and longest line of sight. Together with the finding that participants choose the more connected street, a relationship is proposed between the individual cognitive processes that occur during wayfinding, relative street connectivity measured through space syntactic techniques and the spatial geometry of the environment. The paper adopts an egocentric approach to gain a greater understanding on how individuals process the axial map.

  7. Imagenological characterization by Computerized Axial Tomography of the primary intracranial tumors

    International Nuclear Information System (INIS)

    A descriptive observational study to 56 patients with imagenological diagnosis of primary intracranial neoplasia attended in the service of imagenology of the Provincial Docent Hospital 'Dr. Antonio Luaces Iraola' was carried out from March 1st 2006 to February 1st 2008, with the aim of characterizing these injuries by Computerized Axial Tomography and establishing an evaluation with the histological diagnosis. A questionnaire with the following variables was applied: sex, presuntive age, clinic, topographical characteristics (location, size, tumoral density, changes with administration of the resistance, calcifications, effect of mass and evaluation of the imagenological diagnosis with the histological diagnosis. Masculine sex and the group of ages of 60 are more predominated. The more frequent clinical manifestations were migraine, convulsions, difficulty to walk and vertigo. The size of the injury that prevailed was of 5, 9 and 2, 1 cm with supratentorial location. The majority of primary intracranial neoplasms were hypodense, and enhancement of the injuries with the administration of the resistance was observed. The mass effect bears a close relation with the location and size of the injury. The imagenological diagnosis fitted in with the histological one, being the gliomas the more frequent histological type

  8. Regional myocardial perfusion assessed by N-13 labeled ammonia and positron emission computerized axial tomography

    International Nuclear Information System (INIS)

    The usefulness of 13NH3 as an indicator of regional myocardial perfusion suitable for positron emission computerized axial tomography (PCT) has been suggested. However, the relationship between myocardial blood flow and uptake of 13NH3 has not been examined quantitatively. It was therefore the purpose of the current investigation to quantitate the relationship of myocardial 13NH3 tissue concentration to myocardial blood flow and to examine its suitability for PCT imaging. Twelve open chest dogs were studied. In 8 of the dogs 25 imaging procedures with 13NH3 and PCT were performed. In the remaining four dogs the relationship between flow and myocardial 13NH3 tissue concentration was assessed by in vitro techniques. The PCT technique provided high quality cross-sectional images of the distribution of 13NH3 in left ventricular myocardium. No significant redistribution of 13NH3 in myocardium occurred with time. Alterations in regional myocardial blood flow resulted in changes of the regional distribution of 13NH3 that were readily appreciated on the PCT images

  9. Development of analysis and processing programs for the numerical diagnosis of head by computed axial tomography

    International Nuclear Information System (INIS)

    The series of basic processing programs for the numerical diagnosis of head by computed axial tomography (CT) were developed as one step connecting to the future automatic screening and diagnosis. The system for this CT numerical processing, consisting of the computer EMI 1010, the mini-computer ECLIPSE S/200, the real time disc operating system (RDOS) and the CRT, is presented. As for the basic programs, the transmission of picture data to the disc (TTRDQ), the picture output (NGRPIC), the noise elimination outside skulls (ERATF), the smoothing process (SM 9PIC), the statistical quantity in the interesting region (ROISTAT), the statistical values of whole pictures (GRSTAT), the measurement of the symmetry of pictures (NCGAPIC), the parallel movement of pictures (MVPIC), the subtraction (SBPIC), the reconstruction of pictures (RCONST) and the Sigma-scan (SIGMASCAN) are explained, showing the many experimental data and pictures, such as the format of the print-out program NGRPIC, the picture of the cross section of a brain, the output data of the statistical quantity in the interesting region ROISTAT, the calculating formula of CGAPIC and the histogram, the picture of a tumor of meninx in a brain utilizing SM9PIC, etc. The pictures utilizing RCONST and slicing a brain into 5 mm thickness, and the pictures of a brain utilizing SIGMASCAN. These pictures were taken out as the output with a line printer. These programs were designed originally, and the characteristics of these programs are explained, especially about the special print-out, the peripheral correction for partial volume effect, the calculation of CT-Weight and the skull elimination. The future effective diagnosis is expected by this program. (Nakai, Y.)

  10. [Correlation between diagnostic hypothesis and result of cranial computed axial tomography].

    Science.gov (United States)

    Nóvak, E M; Terabe, F; Nasimoto, A L; Carvalho, P H; Loper, A D; Büchele, F S; Nogara, J C

    2001-09-01

    The use of computed axial tomography (CT) in the investigation of neurologic disorders is attractive for its disponibility in the health services. However, the indications of the exam and the correlation with the clinical features has not been frequently studied. We study correlation between the requests of CT and the findings reported by the radiologist, in 367 exams performed from 07/1995 to 07/ 1996. The mean age was 31.7 +/- 22.9 years. The CT were requested in decrescent order of frequency by the Services of Neurology (36.2%), Emergency room (17.4%), Pediatric Neurology (16.9%) and Internal Medicine (5.9%). The CT was more indicated in cases of seizures (30%), headache (26.2%), motor impairment (20.2%) and reduction of conscience level (16.9%). The main hypothetic diagnosis were "to discard anatomic lesions" (9.0%), not specified stroke (8.2%) and neurocisticercosis (8.2%). The result of the CT was normal in 50.4% of the exams specially those requested in cases of headache (94.4%), seizures (71.4%) and "to discard anatomic lesions"(66.7%). The more frequently CT abnormalities were hydrocephalus (5.4%), ischemic stroke (5.4%) and neoplasm (3.5%) The greatest rates of correlation were among those to discard anatomic lesions (66,7%), hydrocephalus (50%), ischemic stroke (50%) and hematoma (50%). We concluded that CT is more helpful if more clinical data is provided in the request form, so aiding the radiologist in the final report. PMID:11593279

  11. Discrepancies in determination of abdominal aortic aneurysms maximum diameter and growth rate, using axial and orhtogonal computed tomography measurements

    International Nuclear Information System (INIS)

    Purpose: Maximum diameter and growth rate of abdominal aortic aneurysms (AAAs) which are currently used as the only variables to set the indication for elective repair are recorded through computed tomography (CT) measurements on an axial plane or on an orthogonal plane that is perpendicular to vessel centerline, interchangeably. We will attempt to record possible discrepancies between the two methods, identify whether such differences could influence therapeutic decisions and determine in which cases this should be expected. Materials and methods: We retrospectively reviewed sixty CT-scans performed in thirty-nine patients. Three-dimensional reconstruction of AAAs has been performed and differences in maximum diameter measured on axial and orthogonal planes were recorded. A measure for asymmetry was introduced termed ShapeIndex defined as the value of section minor over major axis and was related with differences in maximum diameter recordings. Growth rates were also determined using both axial and orthogonal measurements. Results: Axial measurements overestimate maximum diameter by 2 ± 2.7 mm (P < 0.001) with a range of 0–12.3 mm. Overall, 20% of the CTs had an axial maximum diameter >5.5 cm indicating the need for intervention whereas, orthogonal diameter was below that threshold. Asymmetry of the axial sections with ShapeIndex ≤ 0.8 was found to be related to an overestimation of maximum diameter by >5 mm. There were no significant differences in growth rates when determined using orthogonal or axial measurements in both examinations (median growth rate: 2.3 mm and 3.3 mm respectively P = 0.2). However there were significant differences when orthogonal measurements were used at initial and axial measurements used at follow-up examination or vice versa (median growth rate: 4.9 mm and 0.9 mm respectively P < 0.001). Conclusions: Although the mean difference between measurements is low there is a wide range among cases, mainly observed in asymmetrical AAAs

  12. Discrepancies in determination of abdominal aortic aneurysms maximum diameter and growth rate, using axial and orhtogonal computed tomography measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kontopodis, Nikolaos, E-mail: kontopodisn@yahoo.gr [Department of Vascular Surgery, University of Crete Medical School, Heraklion (Greece); Metaxa, Eleni, E-mail: emmetaxa@gmail.com [Institute of Applied and Computational Mathematics, Foundation for Research and Technology-Hellas, Heraklion, Crete (Greece); Gionis, Michalis, E-mail: gkionismichalis@yahoo.gr [Department of Vascular Surgery, University of Crete Medical School, Heraklion (Greece); Papaharilaou, Yannis, E-mail: yannisp@iacm.forth.gr [Institute of Applied and Computational Mathematics, Foundation for Research and Technology-Hellas, Heraklion, Crete (Greece); Ioannou, Christos V., E-mail: ioannou@med.uoc.gr [Department of Vascular Surgery, University of Crete Medical School, Heraklion (Greece)

    2013-09-15

    Purpose: Maximum diameter and growth rate of abdominal aortic aneurysms (AAAs) which are currently used as the only variables to set the indication for elective repair are recorded through computed tomography (CT) measurements on an axial plane or on an orthogonal plane that is perpendicular to vessel centerline, interchangeably. We will attempt to record possible discrepancies between the two methods, identify whether such differences could influence therapeutic decisions and determine in which cases this should be expected. Materials and methods: We retrospectively reviewed sixty CT-scans performed in thirty-nine patients. Three-dimensional reconstruction of AAAs has been performed and differences in maximum diameter measured on axial and orthogonal planes were recorded. A measure for asymmetry was introduced termed ShapeIndex defined as the value of section minor over major axis and was related with differences in maximum diameter recordings. Growth rates were also determined using both axial and orthogonal measurements. Results: Axial measurements overestimate maximum diameter by 2 ± 2.7 mm (P < 0.001) with a range of 0–12.3 mm. Overall, 20% of the CTs had an axial maximum diameter >5.5 cm indicating the need for intervention whereas, orthogonal diameter was below that threshold. Asymmetry of the axial sections with ShapeIndex ≤ 0.8 was found to be related to an overestimation of maximum diameter by >5 mm. There were no significant differences in growth rates when determined using orthogonal or axial measurements in both examinations (median growth rate: 2.3 mm and 3.3 mm respectively P = 0.2). However there were significant differences when orthogonal measurements were used at initial and axial measurements used at follow-up examination or vice versa (median growth rate: 4.9 mm and 0.9 mm respectively P < 0.001). Conclusions: Although the mean difference between measurements is low there is a wide range among cases, mainly observed in asymmetrical AAAs

  13. Linear fractures invisible on routine axial computed tomography. A pitfall at radiological screening for minor head injury

    International Nuclear Information System (INIS)

    Computed tomography (CT) is now widely used as the only screening method for fractures in patients with head injury. However, clear depiction of a fracture requires a discontinuity in the skull, so linear fractures parallel to the CT slice may not be visualized. We retrospectively evaluated 302 patients with minor head injuries aged from 0 to 91 years, who had undergone routine skull radiography (anteroposterior and lateral views) and head CT to study these types of fracture and discuss the risk of nondetection. Three patients had linear fractures (0.99%) that were invisible on bone window axial CT but detected on skull radiography, which all ran parallel to the scan slice. Two patients developed acute epidural hematoma or traumatic subarachnoid hemorrhage. Evaluation of head injury by only axial CT may miss such fractures and result in sequelae, so diagnosticians should be alert to the possible presence of this type of fracture. (author)

  14. Radiation dose to the head, and particularly to the lens of the eye, during axial tomography with the EMI scanner

    International Nuclear Information System (INIS)

    Radiation dose to the lens of the eye was estimated using thermoluminescence and film dosimetry on patients undergoing computerised axial skull tomography with the EMI scanner, and also on various phantoms. The dose decreases from the lateral margin of the right eye to the lateral margin of the left eye. During conventional three-layer tomography, maximal exposure of the eye is about 0.6 R (1.55 x 10-4 C x kg-1), produced entirely by scatter. Direct irradiation of the plane of the orbits produces a maximal exposure rate of 3 R (7.7 x 10-4 C x kg-1). Maximal dose to the head depends on skull size and is about 4 R (approximately 10-3 C x kg-1). The local dose dependence of the eyes was confirmed theoretically by drawing up a computer programme, and was related to the method used by the EMI scanner. (orig.)

  15. The feasibility of axial and coronal combined imaging using multi-detector row computed tomography for the diagnosis and treatment of a primary spontaneous pneumothorax

    Directory of Open Access Journals (Sweden)

    Kim Do

    2011-05-01

    Full Text Available Abstract Background The preoperative detection of emphysema like changes (ELCs is necessary for the successful treatment of pneumothorax. High resolution computed tomography (HRCT has been used for the preoperative detection of ELCs. However, the traditional HRCT method uses only the axial view, which is perpendicular to the distribution of ELCs. This is not an ideal diagnostic method for the evaluation of ELCs. Methods Forty-eight patients with pneumothorax had multi-detector computed tomography (MDCT reconstruction using the coronal view. ELCs were evaluated in the axial and coronal view by a radiologist. A surgeon performed intra-operative examinations of the ELCs. The sensitivity of the different views was compared. Results The detection sensitivity was 74.4% (70/94 for the axial view and 91.5% (86/94 for the axial-coronal combined view. The intra-operative detection rate was 95.7% (90/94. The preoperative detection of ELCs on the axial-coronal combined view was significantly higher than on the conventional axial view alone (p Conclusions Evaluation of ELCs on the axial and coronal combined HRCT improved the sensitivity of preoperative detection of ELCs compared to the conventional single axial HRCT. This increased sensitivity will help decrease the recurrence with VATS.

  16. Reproducibility of Abdominal Aortic Aneurysm Diameter Measurement and Growth Evaluation on Axial and Multiplanar Computed Tomography Reformations

    International Nuclear Information System (INIS)

    Purpose: To compare different methods measuring abdominal aortic aneurysm (AAA) maximal diameter (Dmax) and its progression on multidetector computed tomography (MDCT) scan. Materials and Methods: Forty AAA patients with two MDCT scans acquired at different times (baseline and follow-up) were included. Three observers measured AAA diameters by seven different methods: on axial images (anteroposterior, transverse, maximal, and short-axis views) and on multiplanar reformation (MPR) images (coronal, sagittal, and orthogonal views). Diameter measurement and progression were compared over time for the seven methods. Reproducibility of measurement methods was assessed by intraclass correlation coefficient (ICC) and Bland–Altman analysis. Results: Dmax, as measured on axial slices at baseline and follow-up (FU) MDCTs, was greater than that measured using the orthogonal method (p = 0.046 for baseline and 0.028 for FU), whereas Dmax measured with the orthogonal method was greater those using all other measurement methods (p-value range: <0.0001–0.03) but anteroposterior diameter (p = 0.18 baseline and 0.10 FU). The greatest interobserver ICCs were obtained for the orthogonal and transverse methods (0.972) at baseline and for the orthogonal and sagittal MPR images at FU (0.973 and 0.977). Interobserver ICC of the orthogonal method to document AAA progression was greater (ICC = 0.833) than measurements taken on axial images (ICC = 0.662–0.780) and single-plane MPR images (0.772–0.817). Conclusion: AAA Dmax measured on MDCT axial slices overestimates aneurysm size. Diameter as measured by the orthogonal method is more reproducible, especially to document AAA progression.

  17. Determination of the antetorsional angle at the femur via axial computer tomography

    International Nuclear Information System (INIS)

    The antetorsional angle was determined in several patient as well as in an isolated femoral bone by means of computer tomography. A comparison with Rippsteins method shows good correlation, taking different definitions of the antetorsional angle into consideration. Due to a mathematical correction method, the CT determination method is independent of the positioning of the patient. (orig.) 891 MG/orig. 892 MB

  18. Computerized axial tomography of the chest for visualization of ''absent'' pulmonary arteries

    Energy Technology Data Exchange (ETDEWEB)

    Sondheimer, H.M. (Upstate Medical Center, Syracuse, NY); Oliphant, M.; Schneider, B.; Kavey, R.E.W.; Blackman, M.S.; Parker, F.B. Jr.

    1982-05-01

    To expand the search for central pulmonary arteries in six patients with absence of cardiac-pulmonary continuity, computerized axial tomography (CAT) of the chest was performed. The CAT scans were compared with previous arteriograms and pulmonary vein wedge angiograms. Three patients with type IV truncus arteriosus were studied, and none had a central, right or left pulmonary artery on CAT scan. However, two patients with tetralogy of Fallot with pulmonary atresia and a patent ductus arteriosus to the right lung demonstrated the presence of a left pulmonary artery. In addition, one child with truncus arteriosus with ''absent'' left pulmonary artery demonstrated a left pulmonary artery on the CAT scan. The CAT scan may therefore enhance our ability to search for disconnected pulmonary arteries in children with complex cyanotic congenital heart disease.

  19. Neutron tomography of axially symmetric objects using 14 MeV neutrons from a portable neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, P., E-mail: peter.andersson@physics.uu.se; Andersson-Sunden, E.; Sjöstrand, H.; Jacobsson-Svärd, S. [Department of Physics and Astronomy, Division of Applied Nuclear Physics, Uppsala University, Lägerhyddsgatan 1, 751 20 Uppsala (Sweden)

    2014-08-01

    In nuclear boiling water reactor cores, the distribution of water and steam (void) is essential for both safety and efficiency reasons. In order to enhance predictive capabilities, void distribution assessment is performed in two-phase test-loops under reactor-relevant conditions. This article proposes the novel technique of fast-neutron tomography using a portable deuterium-tritium neutron generator to determine the time-averaged void distribution in these loops. Fast neutrons have the advantage of high transmission through the metallic structures and pipes typically concealing a thermal-hydraulic test loop, while still being fairly sensitive to the water/void content. However, commercially available fast-neutron generators also have the disadvantage of a relatively low yield and fast-neutron detection also suffers from relatively low detection efficiency. Fortunately, some loops are axially symmetric, a property which can be exploited to reduce the amount of data needed for tomographic measurement, thus limiting the interrogation time needed. In this article, three axially symmetric test objects depicting a thermal-hydraulic test loop have been examined; steel pipes with outer diameter 24 mm, thickness 1.5 mm, and with three different distributions of the plastic material POM inside the pipes. Data recorded with the FANTOM fast-neutron tomography instrument have been used to perform tomographic reconstructions to assess their radial material distribution. Here, a dedicated tomographic algorithm that exploits the symmetry of these objects has been applied, which is described in the paper. Results are demonstrated in 20 rixel (radial pixel) reconstructions of the interior constitution and 2D visualization of the pipe interior is demonstrated. The local POM attenuation coefficients in the rixels were measured with errors (RMS) of 0.025, 0.020, and 0.022 cm{sup −1}, solid POM attenuation coefficient. The accuracy and precision is high enough to provide a useful

  20. Neutron tomography of axially symmetric objects using 14 MeV neutrons from a portable neutron generator

    International Nuclear Information System (INIS)

    In nuclear boiling water reactor cores, the distribution of water and steam (void) is essential for both safety and efficiency reasons. In order to enhance predictive capabilities, void distribution assessment is performed in two-phase test-loops under reactor-relevant conditions. This article proposes the novel technique of fast-neutron tomography using a portable deuterium-tritium neutron generator to determine the time-averaged void distribution in these loops. Fast neutrons have the advantage of high transmission through the metallic structures and pipes typically concealing a thermal-hydraulic test loop, while still being fairly sensitive to the water/void content. However, commercially available fast-neutron generators also have the disadvantage of a relatively low yield and fast-neutron detection also suffers from relatively low detection efficiency. Fortunately, some loops are axially symmetric, a property which can be exploited to reduce the amount of data needed for tomographic measurement, thus limiting the interrogation time needed. In this article, three axially symmetric test objects depicting a thermal-hydraulic test loop have been examined; steel pipes with outer diameter 24 mm, thickness 1.5 mm, and with three different distributions of the plastic material POM inside the pipes. Data recorded with the FANTOM fast-neutron tomography instrument have been used to perform tomographic reconstructions to assess their radial material distribution. Here, a dedicated tomographic algorithm that exploits the symmetry of these objects has been applied, which is described in the paper. Results are demonstrated in 20 rixel (radial pixel) reconstructions of the interior constitution and 2D visualization of the pipe interior is demonstrated. The local POM attenuation coefficients in the rixels were measured with errors (RMS) of 0.025, 0.020, and 0.022 cm−1, solid POM attenuation coefficient. The accuracy and precision is high enough to provide a useful

  1. Usefulness of thin axial images of computerized tomography angiography for surgery on paraclinoid carotid artery aneurysms

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, Shiro; Deguchi, Jun; Arai, Motohiro; Tanaka, Hideo; Ohta, Tomio [Osaka Medical Coll., Takatsuki (Japan)

    1995-08-01

    Ten cases involving a total of 13 aneurysms located in the clinoid portion of the carotid artery were included in this study according to Al-Radham`s classification. Non-ionic, iodinated contrast solution, a total of 2 ml/ kg, was intravenously infused at a rate of 2 ml/sec. Helical scanning was begun 30 seconds after initiating the infusion, 1 mm pitch/1.5 second/rotation. 3-D images and original images of axial slices were compared to conventional angiography, DSA and surgical findings. The 3-D images of 3-D-CT-A were able to demonstrate both aneurysms located in the C2 segment of the carotid artery (groups I and II), and five of nine carotid cave aneurysms (group III). The aneurysms located more proximally (group IV or V) could not be visualized. Original axial images of 3-D-CT-A, on the other hand, clearly demonstrated the C2, C3 and C4 segment of the carotid artery, dome and neck of the aneurysm and bone structures such as the anterior clinoid process (ACP) and sella turcica in all cases. 3-D-CT-A is known to have several advantages in cases involving common locations around the Willis ring: multiple aneurysms on a single approach line, a giant aneurysm whose neck is not clearly demonstrated, or bony structures disturbing the access to aneurysms. However, it has been generally regarded that 3-D-CT-A is of little value for diagnosing paraclinoid internal carotid artery aneurysms. This study demonstrated that a series of original axial images of 3-D-CT-A provides excellent information regarding surgical anatomy; each segment of the carotid artery, neck and dome of the aneurysms, the ACP and its topographic relations to the aneurysm, calcification, and so forth. Since aneurysms can be visualized even in the presence of clips applied to adjacent aneurysms, original images are useful for the follow-up of these specific untreated aneurysms. (J.P.N.).

  2. Usefulness of thin axial images of computerized tomography angiography for surgery on paraclinoid carotid artery aneurysms

    International Nuclear Information System (INIS)

    Ten cases involving a total of 13 aneurysms located in the clinoid portion of the carotid artery were included in this study according to Al-Radham's classification. Non-ionic, iodinated contrast solution, a total of 2 ml/ kg, was intravenously infused at a rate of 2 ml/sec. Helical scanning was begun 30 seconds after initiating the infusion, 1 mm pitch/1.5 second/rotation. 3-D images and original images of axial slices were compared to conventional angiography, DSA and surgical findings. The 3-D images of 3-D-CT-A were able to demonstrate both aneurysms located in the C2 segment of the carotid artery (groups I and II), and five of nine carotid cave aneurysms (group III). The aneurysms located more proximally (group IV or V) could not be visualized. Original axial images of 3-D-CT-A, on the other hand, clearly demonstrated the C2, C3 and C4 segment of the carotid artery, dome and neck of the aneurysm and bone structures such as the anterior clinoid process (ACP) and sella turcica in all cases. 3-D-CT-A is known to have several advantages in cases involving common locations around the Willis ring: multiple aneurysms on a single approach line, a giant aneurysm whose neck is not clearly demonstrated, or bony structures disturbing the access to aneurysms. However, it has been generally regarded that 3-D-CT-A is of little value for diagnosing paraclinoid internal carotid artery aneurysms. This study demonstrated that a series of original axial images of 3-D-CT-A provides excellent information regarding surgical anatomy; each segment of the carotid artery, neck and dome of the aneurysms, the ACP and its topographic relations to the aneurysm, calcification, and so forth. Since aneurysms can be visualized even in the presence of clips applied to adjacent aneurysms, original images are useful for the follow-up of these specific untreated aneurysms. (J.P.N.)

  3. Utility of computed axial tomography angiography in anatomic evaluation of pediatric patients with congenital heart diseases

    International Nuclear Information System (INIS)

    Although echocardiogram and cardiac catheterization are used as first option tools for congenital heart diseases diagnosis, computed tomography angiography is a minimally invasive exam that through two to three dimensional images in real time gives an adequate approach to patients having this type of pathologies that require a rapid and precise evaluation of its extra cardiac anatomy. Objective: describe the institutional experience from August 2005 to August 2006 in the use of angiography by tomography as a complementary diagnostic method in the evaluation of pediatric patients with congenital heart diseases. Method: serial descriptive study. 58 pediatric patients with clinical and echocardiographic diagnosis of congenital heart diseases were evaluated through the General Electric Multislice Light peed/16 scanner. Results: 58 patients with history of congenital heart disease were evaluated through CT angiography. Mean age was 2.4 ± 4.03 years. Twenty (33.8%) had diagnosis of pulmonary atresia, four (6.7%) had tricuspid atresia, eight (13.5%,) had double-outlet right ventricle, seven (11.8%) had tetralogy of Fallot, nine (15.2%) had alterations of the aortic arch, seven (11.8%) had coarctation of the aorta two (3.3%) had interrupted aortic arch, six (10.3%) had persistent ductus arteriosus, four (6.7%) had anomalous venous drainage and three (5.1 %) had transposition of the great arteries. High quality images that allowed assessing the precise vascular anatomy were obtained. Conclusions: computed tomography angiography turned out to be a useful tool in the diagnostic approach of congenital heart diseases, because it allowed a tridimensional anatomic reconstruction. New studies that may permit the assessment of sensitivity, specificity and concordance level of this technique with other invasive diagnostic methods available for the diagnosis of this type of diseases, are required

  4. Principle of multi-sections of plane or axial transverse tomography using recorded fluoroscopic images

    Energy Technology Data Exchange (ETDEWEB)

    Katakura, Tsuyoshi (Tohoku Univ., Sendai (Japan))

    1983-11-01

    In the studies of radiological technology, it is very important that we should research for improved functions of conventional equipment. The experimental study has been performed as to the possibility for the application of X-TV system for the synthesis of plane or axial transverse tomographic images. By this method, it is possible to obtain any of multisection images which are constructed from the video-images recorded during one linear, circular or one rotary motion of the X-ray tube. On the plane tomographic method, each recorded image is displaced following to exposure angle and height-ratio of the plane, therefore; multi-tomographic images can be obtained on the storage tube surface when recorded images are synthesized reversely to cancel displacement. On the transverse tomographic method, selected slit-signals from each of the recorded frames are back-projected on the storage tube surface and are reconstructed as tomographic images. Therefore, other slit-signals from the same video images reconstruct another tomographic section.

  5. Principle of multi-sections of plane or axial transverse tomography using recorded fluoroscopic images

    International Nuclear Information System (INIS)

    In the studies of radiological technology, it is very important that we should research for improved functions of conventional equipment. The experimental study has been performed as to the possibility for the application of X-TV system for the synthesis of plane or axial transverse tomographic images, By this method, it is possible to obtain any of multisection images which are constructed from the video-images recorded during one linear, circular or one rotary motion of the X-ray tube. On the plane tomographic method, each recorded images are displaced following to exposure angle and height-ratio of the plane, therefore, multi-tomographic images can be obtained on the storage tube surface when recorded images are synthesized reversely to cancel displacement. On the transverse tomographic method, selected slit-signals from each of the recorded frames are back-projected on the storage tube surface and are reconstructed as tomographic images. Therefore, other slit-signals from the samevideo images reconstruct another tomographic section. We have shown the synthesized images obtained with chest, lead wire and dried lumbar bone. (author)

  6. Compton scatter axial tomography with x-rays: SCAT-CAT.

    Science.gov (United States)

    Brateman, L; Jacobs, A M; Fitzgerald, L T

    1984-11-01

    A method of extracting information from the backscattered field produced in parallel beam x-ray computed tomography (CT) is presented. A calculational model to predict the backscattered field based on Compton scattering is described, and the model is verified by measurements of simple phantoms. The phantoms tested--cylinders of polymethylmethacrylate (PMM) with air gaps and aluminium rods placed internally--are irradiated on a scanning assembly, built to simulate a first generation CT scanner with a transmission and a scatter detector (the SCAT-CAT). Data from the transmission detector are reconstructed by traditional CT methods to provide a transmission image; it is the data from the backscatter detector which are analysed in this study. After verification of the model for the scattered field calculations, a method of extracting information from the scattered field is developed, based on ratios of scatter signals from non-uniform to uniform phantoms. This method is demonstrated for predicted data of a simulated phantom and for measured data of the same and two additional phantoms. The method is very sensitive to air gaps in the phantoms because of the relative electron density of air with respect to PMM; it is not as sensitive to aluminium rods for the same reason. Various methods of applying the scattered field information to produce an image representing a simulated phantom are considered, and a preferred method is chosen to reconstruct scattered field data into an image for the three phantoms studied. PMID:6505017

  7. Comparison of coronal and axial computed tomography measurements of mediastinal nodes before primary surgery for non-small cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Guinet, Claude [Department of Radiology, Hôtel Dieu Hospital, AP-HP, 1, Place du Parvis Notre-Dame, 75181 Paris Cedex (France); Rousset, Pascal, E-mail: roussetpascal@gmail.com [Department of Radiology, Hôtel Dieu Hospital, AP-HP, 1, Place du Parvis Notre-Dame, 75181 Paris Cedex (France); Bobbio, Antonio; Alifano, Marco [Department of Thoracic Surgery, Hôtel Dieu Hospital, AP-HP, 1, Place du Parvis Notre-Dame, 75181 Paris Cedex (France); Damotte, Diane [Department of Pathology, Hôtel Dieu Hospital, AP-HP, 1, Place du Parvis Notre-Dame, 75181 Paris Cedex (France); Régnard, Jean-François [Department of Thoracic Surgery, Hôtel Dieu Hospital, AP-HP, 1, Place du Parvis Notre-Dame, 75181 Paris Cedex (France); Buy, Jean-Noël [Department of Radiology, Hôtel Dieu Hospital, AP-HP, 1, Place du Parvis Notre-Dame, 75181 Paris Cedex (France)

    2012-09-15

    Objective: To assess computed tomography (CT) evaluation of mediastinal nodes in non-small cell lung cancer to predict metastatic involvement by measurement of their axis and surface area in the coronal plane, as compared to standard short-axis measures in the axial plane. Methods: Evaluation of mediastinal nodes was retrospectively performed on CT scans of 100 patients before thoracotomy. In all patients, mediastinal dissection was performed in the appropriate stations (n = 264) according to the side (59 right, 41 left) of the tumor. Measurements of short axis and surface area of the largest node in each dissected station were performed on axial and coronal planes. Results: By using the standard threshold of axial short axis ≥10 mm, sensitivity and specificity were 25% and 98%, respectively. Areas under receiver operating characteristic curves were 0.828 and 0.821 for axial short axis and axial surface area data. For comparison, areas under receiver operating characteristic curves were 0.843 and 0.845 for coronal short axis and coronal surface area data, respectively. So, for a specificity of 98%, sensitivity was 29% for coronal short axis ≥11 mm and 33% for coronal surface area ≥123 mm{sup 2}. When using axial short axis ≥10 mm or coronal surface area ≥120 mm{sup 2}, sensitivity was 45%, whereas specificity remained at 96%. Conclusion: Coronal measurements of mediastinal nodes give a slightly albeit non-significant improvement of diagnostic accuracy over axial ones. If both axial short axis and coronal surface area are taken into account, accuracy is improved.

  8. Ultrastructural evidence of the excretory function in the asteroid axial organ (Asteroidea, Echinodermata).

    Science.gov (United States)

    Ezhova, O V; Egorova, E A; Malakhov, V V

    2016-05-01

    The ultrastructure of the axial organ of Asterias amurensis has been studied The organ is a network of canals of the axial coelom separated by haemocoelic spaces. The axial coelom is lined with two types of monociliary cells: podocytes and musculo-epithelial cells. Podocytes form numerous basal processes adjacent to the basal lamina on the coelomic side. Musculo-epithelial cells form processes running along the basal lamina. Some bundles of these processes wrapped in the basal lamina pass through haemocoelic spaces between neighboring coelomic canals. It is hypothesized that the axial organ serves for filtration of fluid from haemocoelic spaces into the axial coelom cavity, from which urine is excreted through the madreporite to the exterior. PMID:27411825

  9. Vertebral Pneumaticity in the Ornithomimosaur Archaeornithomimus (Dinosauria: Theropoda Revealed by Computed Tomography Imaging and Reappraisal of Axial Pneumaticity in Ornithomimosauria.

    Directory of Open Access Journals (Sweden)

    Akinobu Watanabe

    Full Text Available Among extant vertebrates, pneumatization of postcranial bones is unique to birds, with few known exceptions in other groups. Through reduction in bone mass, this feature is thought to benefit flight capacity in modern birds, but its prevalence in non-avian dinosaurs of variable sizes has generated competing hypotheses on the initial adaptive significance of postcranial pneumaticity. To better understand the evolutionary history of postcranial pneumaticity, studies have surveyed its distribution among non-avian dinosaurs. Nevertheless, the degree of pneumaticity in the basal coelurosaurian group Ornithomimosauria remains poorly known, despite their potential to greatly enhance our understanding of the early evolution of pneumatic bones along the lineage leading to birds. Historically, the identification of postcranial pneumaticity in non-avian dinosaurs has been based on examination of external morphology, and few studies thus far have focused on the internal architecture of pneumatic structures inside the bones. Here, we describe the vertebral pneumaticity of the ornithomimosaur Archaeornithomimus with the aid of X-ray computed tomography (CT imaging. Complementary examination of external and internal osteology reveals (1 highly pneumatized cervical vertebrae with an elaborate configuration of interconnected chambers within the neural arch and the centrum; (2 anterior dorsal vertebrae with pneumatic chambers inside the neural arch; (3 apneumatic sacral vertebrae; and (4 a subset of proximal caudal vertebrae with limited pneumatic invasion into the neural arch. Comparisons with other theropod dinosaurs suggest that ornithomimosaurs primitively exhibited a plesiomorphic theropod condition for axial pneumaticity that was extended among later taxa, such as Archaeornithomimus and large bodied Deinocheirus. This finding corroborates the notion that evolutionary increases in vertebral pneumaticity occurred in parallel among independent lineages of bird

  10. Preoperative lymph-node staging of invasive urothelial bladder cancer with ¹⁸F-fluorodeoxyglucose positron emission tomography/computed axial tomography and magnetic resonance imaging: correlation with histopathology

    DEFF Research Database (Denmark)

    Jensen, Thor Knak; Holt, Per; Gerke, Oke;

    2011-01-01

    OBJECTIVE: The treatment and prognosis of bladder cancer are based on the depth of primary tumour invasion and the presence of metastases. A highly accurate preoperative tumour, node, metastasis (TNM) staging is critical to proper patient management and treatment. This study retrospectively...... investigated the value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed axial tomography (¹⁸F-FDG PET/CT) and magnetic resonance imaging (MRI) for preoperative N staging of bladder cancer. Material and methods. From June 2006 to January 2008, 48 consecutive patients diagnosed with bladder...

  11. Are Hox genes ancestrally involved in axial patterning? Evidence from the hydrozoan Clytia hemisphaerica (Cnidaria.

    Directory of Open Access Journals (Sweden)

    Roxane Chiori

    Full Text Available BACKGROUND: The early evolution and diversification of Hox-related genes in eumetazoans has been the subject of conflicting hypotheses concerning the evolutionary conservation of their role in axial patterning and the pre-bilaterian origin of the Hox and ParaHox clusters. The diversification of Hox/ParaHox genes clearly predates the origin of bilaterians. However, the existence of a "Hox code" predating the cnidarian-bilaterian ancestor and supporting the deep homology of axes is more controversial. This assumption was mainly based on the interpretation of Hox expression data from the sea anemone, but growing evidence from other cnidarian taxa puts into question this hypothesis. METHODOLOGY/PRINCIPAL FINDINGS: Hox, ParaHox and Hox-related genes have been investigated here by phylogenetic analysis and in situ hybridisation in Clytia hemisphaerica, an hydrozoan species with medusa and polyp stages alternating in the life cycle. Our phylogenetic analyses do not support an origin of ParaHox and Hox genes by duplication of an ancestral ProtoHox cluster, and reveal a diversification of the cnidarian HOX9-14 genes into three groups called A, B, C. Among the 7 examined genes, only those belonging to the HOX9-14 and the CDX groups exhibit a restricted expression along the oral-aboral axis during development and in the planula larva, while the others are expressed in very specialised areas at the medusa stage. CONCLUSIONS/SIGNIFICANCE: Cross species comparison reveals a strong variability of gene expression along the oral-aboral axis and during the life cycle among cnidarian lineages. The most parsimonious interpretation is that the Hox code, collinearity and conservative role along the antero-posterior axis are bilaterian innovations.

  12. Study of the relationship and importance of clinical semiology, axial computed tomography and electroneuromyography in lumbar radioculopathies

    OpenAIRE

    Murade Emílio Cezar Mamede; Hungria Neto José Soares; Avanzi Osmar

    2002-01-01

    The authors evaluated forty-three patients with clinical suspect of lumbar radiculopathy caused by disk hernia, concerning to clinical semiology, computed tomography and electromyography were studied and their correlations. The clinical semiology was altered in 100,0% of the patients, the computed tomography in 90,7% and the electromyography in 88,7%. The correlation among the three exams didnt show any prevalency among any of the possible associations. The authors emphasize the importance of...

  13. Limitaciones de la tomografia axial computada en la localizacion de quistes hidatidicos abdominales en pacientes con confirmacion inmunodiagnostica Limitations of computerized axial tomography in the localization of abdominal hydatid cysts in patients with immunodiagnostic confirmation

    Directory of Open Access Journals (Sweden)

    E. A. Guarnera

    1984-12-01

    Full Text Available Se describe el aporte de la prueba de doble disfusión arco 5 (DD5 al diagnóstico de la hidatidosis en dos pacientes con operaciones previas. En una de ellas, asintomática, la reacción positiva a los cinco años de su última intervención quirúrgica por hidatidosis, permitió diagnosticar la presencia de quistes cuya localización abdominal fue establecida por la tomografía axial computada (TAC. En el otro caso, sintomático, aunque operado de hidatidosis nueve años antes, la positividad a la DD5 confirmó la etiología de la enfermedad que se había sospechado por centellografía, TAC y su historia clínica. En ambos casos, sin embargo, se hallaron en el acto quirúrgico otros quistes abdominales cuyas imágenes no habían sido reveladas en los estudios a los que se las había sometido.The contribution of the arc 5 double diffusion test (DD5 to the diagnosis of hydatidosis in two patients with previous surgery for this parasitic infection is described. In one of the patients, who was asymptomatic, the diagnosis was established on the basis of a positive DD5 reaction five years after her last surgical intervention. The abdominal location of cysts was revealed by computerized axial tomography (CAT. The other patient had been operated on for hydatidosis nine years earlier and showed symptoms. Positivity to the DD5 test confirmed the etiology of the disease, which had been suspected on the basis of her clinical history and the findings of scintillographic and CAT studies. In both cases, however, other abdominal cysts were found at surgery whose images had not been revealed in the previous studies.

  14. Preparation of carbon-11 labelled acetate and palmitic acid for the study of myocardial metabolism by emission-computerised axial tomography

    International Nuclear Information System (INIS)

    Methods have been developed for the labelling of acetate and palmitic acid with the positron-emitting radionuclide, 11C(T=20.4 min). Labelling was achieved via carbonation of the appropriate alkyl magnesium bromide (methyl magnesium bromide or n-pentadecyl magnesium bromide) with 11C-labelled carbon dioxide produced by the 14Np(p,α)11C nuclear reaction. The radiochemical yield and speed of each method of labelling are such that a radiochemically pure product is obtained in injectable form and in activity (>10 mCi) suitable for the study of myocardial metabolism by emission-computerised axial tomography. High pressure liquid chromatography and thin layer chromatography were used to assess the radiochemical purity of each radiopharmaceutical. The specific activity of 11C-labelled acetate was estimated by an enzymic procedure to be greater than 0.5 Ci/μmole. (author)

  15. Prosthesis alignment affects axial rotation motion after total knee replacement: a prospective in vivo study combining computed tomography and fluoroscopic evaluations

    Directory of Open Access Journals (Sweden)

    Harman Melinda K

    2012-10-01

    Full Text Available Abstract Background Clinical consequences of alignment errors in total knee replacement (TKR have led to the rigorous evaluation of surgical alignment techniques. Rotational alignment in the transverse plane has proven particularly problematic, with errors due to component malalignment relative to bone anatomic landmarks and an overall mismatch between the femoral and tibial components’ relative positions. Ranges of nominal rotational alignment are not well defined, especially for the tibial component and for relative rotational mismatch, and some studies advocate the use of mobile-bearing TKR to accommodate the resulting small rotation errors. However, the relationships between prosthesis rotational alignment and mobile-bearing polyethylene insert motion are poorly understood. This prospective, in vivo study evaluates whether component malalignment and mismatch affect axial rotation motions during passive knee flexion after TKR. Methods Eighty patients were implanted with mobile-bearing TKR. Rotational alignment of the femoral and tibial components was measured from postoperative CT scans. All TKR were categorized into nominal or outlier groups based on defined norms for surgical rotational alignment relative to bone anatomic landmarks and relative rotational mismatch between the femoral and tibial components. Axial rotation motion of the femoral, tibial and polyethylene bearing components was measured from fluoroscopic images acquired during passive knee flexion. Results Axial rotation motion was generally accomplished in two phases, dominated by polyethylene bearing rotation on the tibial component in early to mid-flexion and then femoral component rotation on the polyethylene articular surface in later flexion. Opposite rotations of the femur-bearing and bearing-baseplate articulations were evident at flexion greater than 80°. Knees with outlier alignment had lower magnitudes of axial rotation and distinct transitions from external to

  16. Comparison of positions of the trochlear groove line and the vertical midline of the pericondylar rectangle on axial computed tomography: a retrospective pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Nizic, Dinko [Zagreb University Hospital Center, Clinical Institute of Diagnostic and Interventional Radiology, Zagreb (Croatia)

    2012-09-15

    To compare the positions of the trochlear groove (TG) line and the vertical midline of the pericondylar rectangle on axial computed tomography (CT). A retrospective pilot study was conducted in February and March 2011 comprising 14 knees in 9 consecutive patients with patellofemoral pain, a normal trochlear angle (124 -145 ), and no medical record of prior knee surgery. After the axial CT image displaying the center of the trochlear groove (''reference cut'') with a normal trochlear angle was identified, the pericondylar rectangle was drawn and located in the first quadrant of the Cartesian rectangular coordinate system. The x-coordinates of the vertical lines passing through the most posterior point of the trochlear groove (TG line) and the midpoints of the horizontal sides of the pericondylar rectangle (vertical midline) were obtained at 2-week intervals and statistically analyzed as matched pairs for differences (Wilcoxon signed rank test), agreements (Bland-Altman plot, intraclass correlation coefficient [ICC]) and relative variations (coefficient of variation [CV]). There were no statistically significant differences between matched pairs (2-tailed p from 0.583 to 0.641) whereas the agreements were substantial (bias = -0.37 and -0.45 respectively, ICC = 0.688 and 0.670 respectively) to almost perfect for duplicate measurements (bias = 0.11 and 0.04 respectively, ICC = 0.975 and 0.998 respectively), with much less relative variation with regard to the vertical midline (CV = 1.22% to CV = 0.34% respectively). The positions of the TG line and the vertical midline of the pericondylar rectangle on axial CT were identical. The latter was identified regardless of trochlear morphology. (orig.)

  17. Comparison of positions of the trochlear groove line and the vertical midline of the pericondylar rectangle on axial computed tomography: a retrospective pilot study

    International Nuclear Information System (INIS)

    To compare the positions of the trochlear groove (TG) line and the vertical midline of the pericondylar rectangle on axial computed tomography (CT). A retrospective pilot study was conducted in February and March 2011 comprising 14 knees in 9 consecutive patients with patellofemoral pain, a normal trochlear angle (124 -145 ), and no medical record of prior knee surgery. After the axial CT image displaying the center of the trochlear groove (''reference cut'') with a normal trochlear angle was identified, the pericondylar rectangle was drawn and located in the first quadrant of the Cartesian rectangular coordinate system. The x-coordinates of the vertical lines passing through the most posterior point of the trochlear groove (TG line) and the midpoints of the horizontal sides of the pericondylar rectangle (vertical midline) were obtained at 2-week intervals and statistically analyzed as matched pairs for differences (Wilcoxon signed rank test), agreements (Bland-Altman plot, intraclass correlation coefficient [ICC]) and relative variations (coefficient of variation [CV]). There were no statistically significant differences between matched pairs (2-tailed p from 0.583 to 0.641) whereas the agreements were substantial (bias = -0.37 and -0.45 respectively, ICC = 0.688 and 0.670 respectively) to almost perfect for duplicate measurements (bias = 0.11 and 0.04 respectively, ICC = 0.975 and 0.998 respectively), with much less relative variation with regard to the vertical midline (CV = 1.22% to CV = 0.34% respectively). The positions of the TG line and the vertical midline of the pericondylar rectangle on axial CT were identical. The latter was identified regardless of trochlear morphology. (orig.)

  18. Coronary computed tomography angiography using prospective electrocardiography-gated axial scans with 64-detector computed tomography. Evaluation of stair-step artifacts and padding time

    International Nuclear Information System (INIS)

    We compared stair-step artifacts and radiation dose between prospective electrocardiography (ECG)-gated coronary computed tomography angiography (prospective CCTA) and retrospective CCTA using 64-detector CT and determined the optimal padding time (PT) for prospective CCTA. We retrospectively evaluated 183 patients [mean heart rate (HR) <65 beats/min, maximum HR instability <5 beats/min] who had undergone CCTA. We scored stair-step artifacts from 1 (severe) to 5 (none) and evaluated the effective dose in 53 patients with retrospective CCTA and 130 with prospective CCTA (PT 200 ms, n=32; PT 50 ms, n=98). Mean artifact scores were 4.3 in both retrospective and prospective CCTAs. However, statistically more arteries scored <3 (nonassessable) on prospective CCTA (P<0.001). Mean scores for prospective CCTA with 200- and 50-ms PT were 4.1 and 4.3, respectively (no significant difference). The radiation dose of prospective CCTA was reduced by 59.1% to 80.7%. Prospective CCTA reduces the radiation dose and allows diagnostic imaging in most cases but shows more nonevaluable artifacts than retrospective CCTA. Use of 50-ms instead of 200-ms PT appears to maintain image quality in patients with a mean HR <65 beats/min and HR instability of <5 beats/min. (author)

  19. Retinal optical coherence tomography at 1 μm with dynamic focus control and axial motion tracking

    Science.gov (United States)

    Cua, Michelle; Lee, Sujin; Miao, Dongkai; Ju, Myeong Jin; Mackenzie, Paul J.; Jian, Yifan; Sarunic, Marinko V.

    2016-02-01

    High-resolution optical coherence tomography (OCT) retinal imaging is important to noninvasively visualize the various retinal structures to aid in better understanding of the pathogenesis of vision-robbing diseases. However, conventional OCT systems have a trade-off between lateral resolution and depth-of-focus. In this report, we present the development of a focus-stacking OCT system with automatic focus optimization for high-resolution, extended-focal-range clinical retinal imaging by incorporating a variable-focus liquid lens into the sample arm optics. Retinal layer tracking and selection was performed using a graphics processing unit accelerated processing platform for focus optimization, providing real-time layer-specific en face visualization. After optimization, multiple volumes focused at different depths were acquired, registered, and stitched together to yield a single, high-resolution focus-stacked dataset. Using this system, we show high-resolution images of the retina and optic nerve head, from which we extracted clinically relevant parameters such as the nerve fiber layer thickness and lamina cribrosa microarchitecture.

  20. Application of the axial tomography computed for the detection of bags of dampness in dry wood of Gmelina arborea (Roxb.)

    International Nuclear Information System (INIS)

    Gmelina arborea (Roxb.) is widely used for commercial reforestation in Costa Rica due to its excellent growth rate and productivity. However, during the lumber drying process, the wooden boards show non-uniform values of final moisture content (MC). The low uniformity in final MC is caused by the presence of wet pockets, originated during the growing process of the tree. The regions with wet pockets present zones with a high MC, which are hard to detect with traditional methods for MC measurements during the wood drying process. It is possible to detect and to set the limits of the presence of wet wood in Gmelina arborea boards using scanning computed tomography (CT-scanning), a technique applied in medical diagnostic. A board with wet pockets is shown in the CT-scanning images in clear color and with low values of the Hounsfield Unit (HU) or CT number. When these values were transformed to wood density, it was determined that wet pockets were in a density of around 190 kg/m3, a value higher than normal wood. Also, it was possible to observe growth tree rings in the CT-scanning images, an important feature for dendrochronological research. The obtained results allowed showing that it is possible to apply this technique in the process of lumber production, to detect the zones with high MC in kiln dried Gmelina arborea wood. (author)

  1. Real-time axial motion detection and correction for single photon emission computed tomography using a linear prediction filter

    International Nuclear Information System (INIS)

    We have developed an algorithm for real-time detection and complete correction of the patient motion effects during single photon emission computed tomography. The algorithm is based on a linear prediction filter (LPC). The new prediction of projection data algorithm (PPDA) detects most motions-such as those of the head, legs, and hands-using comparison of the predicted and measured frame data. When the data acquisition for a specific frame is completed, the accuracy of the acquired data is evaluated by the PPDA. If patient motion is detected, the scanning procedure is stopped. After the patient rests in his or her true position, data acquisition is repeated only for the corrupted frame and the scanning procedure is continued. Various experimental data were used to validate the motion detection algorithm; on the whole, the proposed method was tested with approximately 100 test cases. The PPDA shows promising results. Using the PPDA enables us to prevent the scanner from collecting disturbed data during the scan and replaces them with motion-free data by real-time rescanning for the corrupted frames. As a result, the effects of patient motion is corrected in real time. (author)

  2. Correlação entre hipótese diagnóstica e laudo de tomografia axial computadorizada craniana Correlation between diagnostic hypothesis and result of cranial computed axial tomography

    Directory of Open Access Journals (Sweden)

    Edison Matos Nóvak

    2001-09-01

    Full Text Available Para avaliar a utilização da tomografia axial computadorizada craniana (TC em nosso meio, analisamos as solicitações de 367 exames consecutivos no período compreendido entre 07/1995 e 07/1996. Houve ampla variação da faixa etária, com média de 31,7 ± 22,9 anos. As especialidades que mais solicitaram o exame foram: Neurologia (36,2%, Pronto Atendimento (17,4%, Neuropediatria (16,9% e Clínica Médica (5,9%. As indicações mais frequentes para o exame foram: convulsão (30%, cefaléia (26,2%, déficit motor (20,2% e redução do nível de consciência (16,9%. As "hipóteses" aventadas com maior frequência foram: afastar lesão estrutural (9,0%, acidente vascular não discriminado (8,2% e neurocisticercose (8,2%. O laudo da TC foi normal em 50,4% dos exames. Os laudos anormais mais frequentes foram: hidrocefalia (5,4%, acidente vascular isquêmico (5,4% e neoplasia (3,5%. As maiores taxas de achados normais foram encontradas nas "hipóteses" de cefaléia (94,4%, convulsão (71,4% e afastar lesão estrutural (66,7%. Os maiores índices de acerto entre hipótese e laudo foram encontrados nas situações de "afastar lesões estruturais" (66,7%, hidrocefalia (50%, acidente vascular cerebral isquêmico (50% e hematoma (50%. Concluimos que a utilização de um recurso auxiliar de diagnóstico como a TC cumpre melhor ainda a sua função se o requisitante do exame preencher com clareza e detalhamento o pedido do exame.The use of computed axial tomography (CT in the investigation of neurologic disorders is attractive for his disponibility in the health services. However, the indications of the exam and the correlation with the clinical features has not been frequently studied. We study correlation between the requests of CT and the findings reported by the radiologist, in 367 exams performed from 07/1995 to 07/ 1996. The mean age was 31.7 ± 22.9 years. The CT were requested in decrescent order of frequency by the Services of Neurology (36

  3. Study of the relationship and importance of clinical semiology, axial computed tomography and electroneuromyography in lumbar radioculopathies Estudo da relação e da importância entre a semiologia clínica, tomografia axial computadorizada e eletroneuromiografia nas radiculopatias lombares

    Directory of Open Access Journals (Sweden)

    Emílio Cezar Mamede Murade

    2002-12-01

    Full Text Available The authors evaluated forty-three patients with clinical suspect of lumbar radiculopathy caused by disk hernia, concerning to clinical semiology, computed tomography and electromyography were studied and their correlations. The clinical semiology was altered in 100,0% of the patients, the computed tomography in 90,7% and the electromyography in 88,7%. The correlation among the three exams didn´t show any prevalency among any of the possible associations. The authors emphasize the importance of clinical semiology, computed tomography and electromyography for a more accurate diagnosis of lumbar radiculopathy following by disk hernia.Os autores estudaram 43 pacientes com suspeita clínica de radiculopatia lombar, causada por hérnia de disco, relacionando os achados da semiologia clínica, tomografia axial computadorizada e eletroneuromiografia, entre si. A semiologia clínica estava alterada em 100,0% dos pacientes, a tomografia axial computadorizada em 90,7% e a eletroneuromiografia em 88,7%. A correlação entre os três exames não mostrou prevalência entre nenhuma associação. Os autores enfatizam a importância da semiologia clínica, tomografia axial computadorizada e eletroneuromiografia para maior exatidão diagnóstica das radiculopatias lombares por hérnia de disco.

  4. Tomography

    International Nuclear Information System (INIS)

    Tomography is a non-intrusive imaging technique being developed at CRNL as an industrial tool for generating quantitative cross-sectional density maps of objects. Of most interest is tomography's ability to: distinguish features within complex geometries where other NDT techniques fail because of the complexity of the geometry; detect/locate small density changes/defects within objects, e.g. void fraction measurements within thick-walled vessels, shrink cavities in castings, etc.; provide quantitative data that can be used in analyses, e.g. of complex processes, or fracture mechanics; and provide objective quantitative data that can be used for (computer-based) quality assurance decisions, thereby reducing and in some cases eliminating the present subjectivity often encountered in NDT. The CRNL program is reviewed and examples are presented to illustrate the potential and the limitations of the technology

  5. Tomography

    International Nuclear Information System (INIS)

    Tomography images of a body are constructed by placing a plurality of surface electrodes at spaced intervals on the body, causing currents to flow in the body (e.g. by applying a potential between each pair of electrodes in turn, or by induction), and measuring the potential between pairs of electrodes, calculating the potential expected in each case on the assumption that the body consists of a medium of uniform impedance, plotting the isopotentials corresponding to the calculated results to create a uniform image of the body, obtaining the ratio between the measured potential and the calculated potential in each case, and modifying the image in accordance with the respective ratios by increasing the assumed impedance along an isopotential in proportion to a ratio greater than unity or decreasing the assumed impedance in proportion to a ratio less than unity. The modified impedances along the isopotentials for each pair of electrodes are superimposed. The calculations are carried out using a computer and the plotting is carried out by a visual display unit and/or a print-out unit. (author)

  6. Limitaciones de la tomografia axial computada en la localizacion de quistes hidatidicos abdominales en pacientes con confirmacion inmunodiagnostica Limitations of computerized axial tomography in the localization of abdominal hydatid cysts in patients with immunodiagnostic confirmation

    OpenAIRE

    Guarnera, E A; V. M. Varela-Díaz

    1984-01-01

    Se describe el aporte de la prueba de doble disfusión arco 5 (DD5) al diagnóstico de la hidatidosis en dos pacientes con operaciones previas. En una de ellas, asintomática, la reacción positiva a los cinco años de su última intervención quirúrgica por hidatidosis, permitió diagnosticar la presencia de quistes cuya localización abdominal fue establecida por la tomografía axial computada (TAC). En el otro caso, sintomático, aunque operado de hidatidosis nueve años antes, la positividad a la DD5...

  7. Evidence for a caudate role in aphasia from FDG positron emission tomography

    International Nuclear Information System (INIS)

    In a recent study correlations between language function and regional glucose metabolism from FDG positron computed tomography were examined. Caudate metabolism correlated with PICA speaking and comprehension factors, as well as BDAE mean writing and reading scores. To identify the language function implicated with caudate metabolism in these eleven patients, twenty subtests making up these two PICA factors and mean BDAE scores were correlated to caudate metabolism. Also a principle components analysis on the twenty subtests identified three factors, only one of which correlated with caudate metabolism. Evidence was found that the caudate has a functional relationship to recognition or motor planning of simple and overlearned materials. This involved simple syntax, low levels of abstraction, identification or sequencing of phonetic and semantic material. This role appeared related to but independent of Broca and frontal lobe function, and may involve the focusing of cortical functions, by allowing two or more regions to interact together

  8. Correlação entre hipótese diagnóstica e laudo de tomografia axial computadorizada craniana Correlation between diagnostic hypothesis and result of cranial computed axial tomography

    OpenAIRE

    Edison Matos Nóvak; Fábio Terabe; André Luís Nasimoto; Paulo Henrique Migliari de Carvalho; Ariane Desirée Loper; Fabiana Schenato Büchele; Júlio César Nogara

    2001-01-01

    Para avaliar a utilização da tomografia axial computadorizada craniana (TC) em nosso meio, analisamos as solicitações de 367 exames consecutivos no período compreendido entre 07/1995 e 07/1996. Houve ampla variação da faixa etária, com média de 31,7 ± 22,9 anos. As especialidades que mais solicitaram o exame foram: Neurologia (36,2%), Pronto Atendimento (17,4%), Neuropediatria (16,9%) e Clínica Médica (5,9%). As indicações mais frequentes para o exame foram: convulsão (30%), cefaléia (26,2%),...

  9. Examinations with computerized cranial axial tomography carried out on patients with epileptic seizures, taking into consideration the EEG and the clinical picture

    International Nuclear Information System (INIS)

    204 patients suffering from epileptic seizures were examined with the help of computerized cranial X-ray tomography; the results were compared with anamnestic, clinical, and EEC-findings. In good agreement with results published in literature, in 54% of the patients pathologic CT's such as tumours, attack scars, changes in ventricles and arachnoid spaces etc. were found. A pathological CT is very likely to appear in male patients who are 30 or even 50 years of age, having partial attacks with elementary symptoms, focal diagnosis in the EEG and a neurological unilateral finding. Especially noteworthy is the tumour detecting rate achieved by CT and the fact that in nearly 5% of the cases CT detected a cerebral lesion which has not been suspected, neither clinically nor in the EEG (4 tumours). This shows clearly that CT represents a heighly valuable diagnostic help, especially for patients with epileptic seizures. (orig./MG)

  10. Hybrid averaging offers high-flow contrast by cost apportionment among imaging time, axial, and lateral resolution in optical coherence tomography angiography.

    Science.gov (United States)

    Li, Peng; Cheng, Yuxuan; Li, Pei; Zhou, Liping; Ding, Zhihua; Ni, Yang; Pan, Cong

    2016-09-01

    The current temporal, wavelength, angular, and spatial averaging approaches trade imaging time and resolution for multiple independent measurements that improve the flow contrast in optical coherence tomography angiography (OCTA). We find that these averaging approaches are equivalent in principle, offering almost the same flow contrast enhancement as the number of averages increases. Based on this finding, we propose a hybrid averaging strategy for contrast enhancement by cost apportionment. We demonstrate that, compared with any individual approach, the hybrid averaging is able to offer a desired flow contrast without severe degradation of imaging time and resolution. Making use of the extended range of a VCSEL-based swept-source OCT, an angular averaging approach by path length encoding is also demonstrated for flow contrast enhancement. PMID:27607943

  11. Axial skeletal CT densitometry

    International Nuclear Information System (INIS)

    Since the discovery of the Roentgen ray a precise and accurate assessment of bone mineral content has been a challenge to many investigators. A number of methods have been developed but no one satisfied. Considering its technical possibilities computed tomography is very promising in determination of bone mineral content (BMC). The new modality enables BMC estimations in the axial skeletal trabecular bone. CT densitometry can be performed on a normal commercially available third generation whole body CT scanner. No dedicated device in a special clinical set-up is necessary. In this study 106 patients, most of them clinically suspected of osteoporosis, were examined. The new method CT densitometry has been evaluated. The results have been correlated to alternative BMC determination methods. (Auth.)

  12. Origin of the Changbai intraplate volcanism in Northeast China:Evidence from seismic tomography

    Institute of Scientific and Technical Information of China (English)

    ZHAO Dapeng; LEI Jianshe; TANG Rongyu

    2004-01-01

    Seismic images of the mantle beneath the active Changbai intraplate volcano in Northeast China determined by teleseismic travel time tomography are presented. The data are measured at a new seismic network consisting of 19 portable stations and 3 permanent stations. The results show a columnar low-velocity (-3 %) anomaly extending to 400 km depth under the Changbai volcano. High velocity anomalies are visible in the mantle transition zone, and deep earthquakes occur at depths of 500-600 km under the region,suggesting that the subducting Pacific slab is stagnant in the transition zone, as imaged clearly also by global tomography.These results suggest that the Changbai intraplate volcano is not a hotspot like Hawaii but a kind of back-arc volcano related to the upwelling of hot asthenospheric materials associated with the deep subduction and stagnancy of the Pacific slab under northeast Asia.

  13. Contrasting Subduction Modes with Slab Tearing beneath Eastern Himalaya: Evidence from Teleseismic P-wave Tomography

    Science.gov (United States)

    Peng, M.; Jiang, M.; Li, Z. H.; Xu, Z.; Chen, Y.; Chan, W. W. W.; Wang, Y.; Yu, C.; Lei, J.

    2014-12-01

    On the eastern margin of the Himalayan orogenic belt, the rapid uplift of the Namche Barwa metamorphic terrane and the significant bending of the Yarlung Zangbo suture zone occur. However, the formation mechanism and dynamics of the Eastern Himalayan Syntaxis is still debated. In order to better understand the deep structures beneath eastern Himalaya, we further deployed 35 broadband seismic stations (2010-2013) around the Namche Barwa Mountain, which is integrated with the existing Lehigh data sets of 45 stations (2003-2004). We totally selected 18,979 high-quality P-wave arrival times from 2,140 teleseismic events to image P-wave teleseismic tomography. The results demonstrate complex deep structures and significantly different subduction modes in the eastern Himalaya. In contrast to the steep subduction of the Indian lithosphere beneath the Eastern Himalayan Syntaxis, the Indian slab flatly subducted in the west, which might extend close to the Bangong-Nujiang Suture and then steeply sink and bend over. The contrasting subduction model results in the tearing and fragmentation of the Indian lithosphere in the transition zone between the flat and steep subduction. Consequently, the upwelling of hot asthenospheric mantle may occur through the slab tear window, which might further lead to the rapid uplift of Namche Barwa and the formation of the Eastern Himalayan Syntaxis. The lateral variation in subduction mode and slab tearing induced asthenospheric mantle upwelling is similar to that observed in the Hellenide and Anatolide domains of the Tethyan orogen.

  14. Seasonal variation in thoracic vessel calcifications: Evidence from a chest computed tomography study

    International Nuclear Information System (INIS)

    Background: Cardiovascular disease incidence and mortality exhibit a winter peak and a summer trough, a fact that could have radiological manifestations. Purpose: To identify possible seasonal trends in the occurrence of thoracic vessel calcifications. Material and Methods: 505 male construction workers (aged 39-80 years) were each imaged once with chest spiral computed tomography (CT) during a 2-year period. Based on visual assessment of calcified plaques (0=no, 1=slight, 2=moderate, 3=extensive calcification), sum scores of atherosclerosis in coronary arteries, in the thoracic aorta, in the pre-cervical artery bases, and overall were constructed. The scores were regressed on the annual rank number of the CT day. Results: By using the cubic regression model, seasonal variation in calcified plaques in coronary arteries (P=0.003), in pre-cervical artery origins (P=0.015), and in the overall sum score (P=0.004) was observed. The peak occurred in January-February and the nadir in August. Depending on the model, about 2-3% of the variation in atherosclerotic calcifications could be explained by the season of imaging. Conclusion: The observed seasonal trend in calcifications parallels with mortality reports. Seasonal variations should be considered in atherosclerosis treatment studies. Confirmatory studies using modern imaging technology are needed in different countries and geographical locations, preferably with repeat imaging of the same individuals

  15. Evidence for anomalous mantle upwelling beneath the Arabian Platform from travel time tomography inversion

    Science.gov (United States)

    Koulakov, Ivan; Burov, Evgeniy; Cloetingh, Sierd; El Khrepy, Sami; Al-Arifi, Nassir; Bushenkova, Natalia

    2016-01-01

    We present a new model of P-velocity anomalies in the upper mantle beneath the Arabian Peninsula, Red Sea, and surrounding regions. This model was computed with the use of travel time data from the global catalogue of the International Seismological Center (ISC) for the years of 1980-2011. The reliability of the model was tested with several synthetic tests. In the resulting seismic model, the Red Sea is clearly associated with a higher P-velocity anomaly in the upper mantle at least down to 300 km depth. This anomaly might be caused by upward deviation of the main mantle interfaces caused by extension and thinning of the lithosphere due to passive rifting. Thick lithosphere of the Arabian Platform is imaged as a high-velocity anomaly down to 200-250 km depth. Below this plate, we observe a low-velocity structure that is interpreted as a hot mantle upwelling. Based on the tomography results, we propose that this upper mantle anomaly may represent hot material that migrates westward and play a major role in the formation of Cenozoic basaltic lava fields in western Arabia. On the northeastern side of the Arabian Plate, we clearly observe a dipping high-velocity zone beneath Zagros and Makran, which is interpreted as a trace of subduction or delamination of the Arabian Plate lithosphere.

  16. More Evidence for the Redshift Dependence of Color from the JLA Supernova Sample Using Redshift Tomography

    Science.gov (United States)

    Li, Miao; Li, Nan; Wang, Shuang; Lanjun, Zhou

    2016-05-01

    In this work, by applying the redshift tomography method to Joint Light-curve Analysis (JLA) supernova sample, we explore the possible redshift-dependence of stretch-luminosity parameter α and color-luminosity parameter β. The basic idea is to divide the JLA sample into different redshift bins, assuming that α and β are piecewise constants. Then, by constraining the ΛCDM model, we check the consistency of cosmology-fit results given by the SN sample of each redshift bin. We also adopt the same technique to explore the possible evolution of β in various subsamples of JLA. Using the full JLA data, we find that α is always consistent with a constant. In contrast, at high redshift β has a significant trend of decreasing, at ˜3.5σ confidence level (CL). Moreover, we find that low-z subsample favors a constant β; in contrast, SDSS and SNLS subsamples favor a decreasing β at 2σ and 3.3σ CL, respectively. Besides, by using a binned parameterization of β, we study the impacts of β's evolution on parameter estimation. We find that compared with a constant β, a varying β yields a larger best-fit value of fractional matter density Ωm0, which slightly deviates from the best-fit result given by other cosmological observations. However, for both the varying β and the constant β cases, the 1σ regions of Ωm0 are still consistent with the result given by other observations.

  17. Cryoelectron tomography of HIV-1 envelope spikes: further evidence for tripod-like legs.

    Directory of Open Access Journals (Sweden)

    Ping Zhu

    2008-11-01

    Full Text Available A detailed understanding of the morphology of the HIV-1 envelope (Env spike is key to understanding viral pathogenesis and for informed vaccine design. We have previously presented a cryoelectron microscopic tomogram (cryoET of the Env spikes on SIV virions. Several structural features were noted in the gp120 head and gp41 stalk regions. Perhaps most notable was the presence of three splayed legs projecting obliquely from the base of the spike head toward the viral membrane. Subsequently, a second 3D image of SIV spikes, also obtained by cryoET, was published by another group which featured a compact vertical stalk. We now report the cryoET analysis of HIV-1 virion-associated Env spikes using enhanced analytical cryoET procedures. More than 2,000 Env spike volumes were initially selected, aligned, and sorted into structural classes using algorithms that compensate for the "missing wedge" and do not impose any symmetry. The results show varying morphologies between structural classes: some classes showed trimers in the head domains; nearly all showed two or three legs, though unambiguous three-fold symmetry was not observed either in the heads or the legs. Subsequently, clearer evidence of trimeric head domains and three splayed legs emerged when head and leg volumes were independently aligned and classified. These data show that HIV-1, like SIV, also displays the tripod-like leg configuration, and, unexpectedly, shows considerable gp41 leg flexibility/heteromorphology. The tripod-like model for gp41 is consistent with, and helps explain, many of the unique biophysical and immunological features of this region.

  18. Multislice computed tomography coronary angiography

    OpenAIRE

    Cademartiri, Filippo

    2005-01-01

    markdownabstract__Abstract__ Computed Tomography (CT) imaging is also known as "CAT scanning" (Computed Axial Tomography). Tomography is from the Greek word "tomos" meaning "slice" or "section" and "graphia" meaning "describing". CT was invented in 1972 by British engineer Godfrey Hounsfield of EMI Laboratories, England, and independently by South Mrican born physicist Allan Cormack of Tufts University, Massachusetts.1 • 2 Hounsfield was later awarded the Nobel Peace Prize and honoured with K...

  19. Positron Emission Tomography (PET) in the oncologic clinical practice

    International Nuclear Information System (INIS)

    We intended to determine the frequency with that the computer axial tomography (TAC), it was able to visualize the lesions extra neoplasia detected by the PET tomography in patients with fully identified primary malignant neoplasia. (Author)

  20. Study of the relationship and importance of clinical semiology, axial computed tomography and electroneuromyography in lumbar radioculopathies Estudo da relação e da importância entre a semiologia clínica, tomografia axial computadorizada e eletroneuromiografia nas radiculopatias lombares

    OpenAIRE

    Emílio Cezar Mamede Murade; José Soares Hungria Neto; Osmar Avanzi

    2002-01-01

    The authors evaluated forty-three patients with clinical suspect of lumbar radiculopathy caused by disk hernia, concerning to clinical semiology, computed tomography and electromyography were studied and their correlations. The clinical semiology was altered in 100,0% of the patients, the computed tomography in 90,7% and the electromyography in 88,7%. The correlation among the three exams didn´t show any prevalency among any of the possible associations. The authors emphasize the import...

  1. BWR AXIAL PROFILE

    International Nuclear Information System (INIS)

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

  2. BWR AXIAL PROFILE

    Energy Technology Data Exchange (ETDEWEB)

    J. Huffer

    2004-09-28

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

  3. Signatures for axial chromodynamics

    International Nuclear Information System (INIS)

    Within the context of basic left-right symmetry and the hypothesis of unification of weak, electromagnetic and strong forces at a mass level approximately equal to 104-106 GeV, relatively light ''mass'' axial gluons, confined or liberated, must be postulated. The authors remark that the existence of such ''light'' axial gluons supplementing the familiar vector octet preserves the successes of QCD, both for deep inelastic processes and charmonium physics. Through the characteristic spin-spin force, generated by their exchange, they may even help resolve some of the discrepancies between vector QCD predictions and charmonium physics. The main remark of this note is that if colour is liberated, not only vector but also axial-vector gluons are produced in high-energy e-e+ experiments, e.g. at PETRA and PEP, with fairly large cross-section. Distinctive decay modes of such liberated axial gluons are noted

  4. Surface nanoscale axial photonics

    OpenAIRE

    Sumetsky, M.; Fini, J. M.

    2011-01-01

    Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger e...

  5. Neuroanatomy of cranial computed tomography

    International Nuclear Information System (INIS)

    Based on the fundamental structures visualized by means of computed tomography, the authors present the functional systems which are relevant in neurology by means of axial cross-sections. All drawings were prepared from original preparations by means of a new technique which is similar to the grey values of X-ray CT and nuclear magnetic resonance tomography. A detailed description is given of the topics of neurofunctional lesions

  6. Computed Tomography Status

    Science.gov (United States)

    Hansche, B. D.

    1983-01-01

    Computed tomography (CT) is a relatively new radiographic technique which has become widely used in the medical field, where it is better known as computerized axial tomographic (CAT) scanning. This technique is also being adopted by the industrial radiographic community, although the greater range of densities, variation in samples sizes, plus possible requirement for finer resolution make it difficult to duplicate the excellent results that the medical scanners have achieved.

  7. Computed Tomography. Chapter 11

    International Nuclear Information System (INIS)

    After its clinical introduction in 1971, computed tomography (CT) developed from an X ray modality that was limited to axial imaging of the brain in neuroradiology into a versatile 3-D whole body imaging modality for a wide range of applications, including oncology, vascular radiology, cardiology, traumatology and interventional radiology. CT is applied for diagnosis and follow-up studies of patients, for planning of radiotherapy, and even for screening of healthy subpopulations with specific risk factors

  8. Evident?

    DEFF Research Database (Denmark)

    Plant, Peter

    2012-01-01

    Quality assurance and evidence in career guidance in Europe are often seen as self-evident approaches, but particular interests lie behind......Quality assurance and evidence in career guidance in Europe are often seen as self-evident approaches, but particular interests lie behind...

  9. On renormalization of axial anomaly

    International Nuclear Information System (INIS)

    It is shown that multiplicative renormalization of the axial singlet current results in renormalization of the axial anomaly in all orders of perturbation theory. It is a necessary condition for the Adler - Bardeen theorem being valid. 10 refs.; 2 figs

  10. Axial compressor stability enhancement

    OpenAIRE

    Houghton, Timothy Oliver.

    2010-01-01

    Aircraft jet engines must operate in a stable manner at all times. One source of instability is compressor stall. Stall problems can be reduced by machining cavities into the compressor casing adjacent to the rotor blades. This ?casing treatment? is the focus of the present work. Two treatment configurations are tested: circumferential grooves cut into the casing above the rotor blades, and axial slots cut into the casing adjacent to the rotor blade leading edges. The performance of a single ...

  11. Grapevine petioles are more sensitive to drought induced embolism than stems: evidence from in vivo MRI and microcomputed tomography observations of hydraulic vulnerability segmentation.

    Science.gov (United States)

    Hochberg, Uri; Albuquerque, Caetano; Rachmilevitch, Shimon; Cochard, Herve; David-Schwartz, Rakefet; Brodersen, Craig R; McElrone, Andrew; Windt, Carel W

    2016-09-01

    The 'hydraulic vulnerability segmentation' hypothesis predicts that expendable distal organs are more susceptible to water stress-induced embolism than the main stem of the plant. In the current work, we present the first in vivo visualization of this phenomenon. In two separate experiments, using magnetic resonance imaging or synchrotron-based microcomputed tomography, grapevines (Vitis vinifera) were dehydrated while simultaneously scanning the main stems and petioles for the occurrence of emboli at different xylem pressures (Ψx ). Magnetic resonance imaging revealed that 50% of the conductive xylem area of the petioles was embolized at a Ψx of -1.54 MPa, whereas the stems did not reach similar losses until -1.9 MPa. Microcomputed tomography confirmed these findings, showing that approximately half the vessels in the petioles were embolized at a Ψx of -1.6 MPa, whereas only few were embolized in the stems. Petioles were shown to be more resistant to water stress-induced embolism than previously measured with invasive hydraulic methods. The results provide the first direct evidence for the hydraulic vulnerability segmentation hypothesis and highlight its importance in grapevine responses to severe water stress. Additionally, these data suggest that air entry through the petiole into the stem is unlikely in grapevines during drought. PMID:26648337

  12. Critical Axial Load

    Directory of Open Access Journals (Sweden)

    Walt Wells

    2008-01-01

    Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.

  13. Evidence for regional catecholamine uptake and storage sites in the transplanted human heart by positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography in combination with the newly introduced catecholamine analogue [11C]hydroxyephedrine ([11C]HED) enables the noninvasive delineation of sympathetic nerve terminals of the heart. To address the ongoing controversy over possible reinnervation of the human transplant, 5 healthy control subjects and 11 patients were studied after cardiac transplant by this imaging approach. Regional [11C]HED retention was compared to regional blood flow as assessed by rubidium-82. Transplant patients were divided into two groups. Group I had recent (less than 1 yr, 4.4 +/- 2.3 mo) surgery, while group II patients underwent cardiac transplantation more than 2 yr before imaging (3.5 +/- 1.3 yr). [11C]HED retention paralleled blood flow in normals, but was homogeneously reduced in group I. In contrast, group II patients revealed heterogeneous [11C]HED retention, with increased uptake in the proximal anterior and septal wall. Quantitative evaluation of [11C]HED retention revealed a 70% reduction in group I and 59% reduction in group II patients (P less than 0.001). In group II patients, [11C]HED retention reached 60% of normal in the proximal anterior wall. These data suggest the presence of neuronal tissue in the transplanted human heart, which may reflect regional sympathetic reinnervation

  14. Evidence for regional catecholamine uptake and storage sites in the transplanted human heart by positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Schwaiger, M.; Hutchins, G.D.; Kalff, V.; Rosenspire, K.; Haka, M.S.; Mallette, S.; Deeb, G.M.; Abrams, G.D.; Wieland, D. (Univ. of Michigan Medical Center, Ann Arbor (USA))

    1991-05-01

    Positron emission tomography in combination with the newly introduced catecholamine analogue ({sup 11}C)hydroxyephedrine (({sup 11}C)HED) enables the noninvasive delineation of sympathetic nerve terminals of the heart. To address the ongoing controversy over possible reinnervation of the human transplant, 5 healthy control subjects and 11 patients were studied after cardiac transplant by this imaging approach. Regional ({sup 11}C)HED retention was compared to regional blood flow as assessed by rubidium-82. Transplant patients were divided into two groups. Group I had recent (less than 1 yr, 4.4 +/- 2.3 mo) surgery, while group II patients underwent cardiac transplantation more than 2 yr before imaging (3.5 +/- 1.3 yr). ({sup 11}C)HED retention paralleled blood flow in normals, but was homogeneously reduced in group I. In contrast, group II patients revealed heterogeneous ({sup 11}C)HED retention, with increased uptake in the proximal anterior and septal wall. Quantitative evaluation of ({sup 11}C)HED retention revealed a 70% reduction in group I and 59% reduction in group II patients (P less than 0.001). In group II patients, ({sup 11}C)HED retention reached 60% of normal in the proximal anterior wall. These data suggest the presence of neuronal tissue in the transplanted human heart, which may reflect regional sympathetic reinnervation.

  15. Paracoccidioidomycosis: high-resolution computed tomography - anatomo-pathological correlation; Paracoccidioidomicose: correlacao da tomografia computadorizada de alta resolucao com a anatomopatologia

    Energy Technology Data Exchange (ETDEWEB)

    Marchiori, Edson; Muniz, Maria Angelica Soares; Santos, Maria Lucia de Oliveira [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Radiologia; Moraes, Heleno Pinto de [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Patologia; Capone, Domenico [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Pneumologia

    2000-12-01

    We reviewed the high-resolution computed tomography scans of 13 patients with paracoccidioidomycosis and correlated the findings with the anatomo-pathological findings of 5 patients. The most frequent findings observed were thickening of the interlobular septa, emphysema, ground glass areas, thickening of bronchial walls, tracheal dilatation, nodules, cavities and evidence of fibrosing disease such as architectural distortion, parenchymatous bands, spicular pleural thickening, intralobular reticulate and thickening with distortion off the axial interstitium. (author)

  16. Calidad de imagen y dosis de radiación de la angiografía coronaria por tomografía computada multidetector con técnica de adquisición axial con gatillado prospectivo Imaging quality and effective radiation dose of prospective ECG-gated axial multidetector row computed tomography coronary angiography Objective

    Directory of Open Access Journals (Sweden)

    Carlos Capuñay

    2011-09-01

    Full Text Available Objetivo. Determinar la calidad de imagen y la dosis de radiación efectiva (DRE de la angiografía coronaria por tomografía computada con adquisición con gatillado prospectivo (ACTC-P en comparación con la técnica de adquisición con gatillado retrospectivo (ACTC-R. Materiales y Métodos. Cuarenta y cinco estudios de ACTC-P fueron analizados en forma retrospectiva para la valoración de la calidad de imagen y DRE, y se compararon con 90 estudios de ACTC-R realizados sin (n = 45 y con (n = 45 modulación de la corriente del tubo de rayos X seleccionados de la base de datos acorde a características demográficas similares. La DRE se comparó entre los tres grupos. La calidad de imagen fue analizada en forma independiente por dos observadores y comparada con el grupo de ACTC-R modulada. Se determinó también la variabilidad interobservador. Resultados. No hubo diferencias significativas en la calidad de imagen entre los dos grupos. La variabilidad interobservador fue k=0,92 (IC 95%: 0,87 a 0,96. La DRE (media ± DS de la ACTC-P fue 2,88 ± 0,37 mSv comparado con 10,50 ± 1,15 mSv (p To determine the imaging quality and effective radiation dose (ERD of prospective ECG-gated multidetector row computed tomography coronary angiography (PMDCT-CA compared to retrospective ECG-gating (RMDCT-CA. Materials and Methods. Forty-five PMDCT-CA scans were retrospectively reviewed for assessing imaging quality and ERD, and compared to 90 RMDCT-CA scans performed with (n= 45 and without (n= 45 tube current modulation, selected from our database on the basis of similar demographical characteristics. ERD was compared between all three groups. Imaging quality was assessed by two independent observers and compared to the imaging quality of the group of RMDCT-CA scans performed with tube current modulation. The interobserver variability was also determined. Results. There were no significant differences in imaging quality between the two groups. Interobserver

  17. 18F-fluorodeoxyglucose positron emission tomography in restaging of colorectal cancer. Evidence-based recommendations and cost-effectiveness

    International Nuclear Information System (INIS)

    Aim, method: Recommendations for the use of FDG-PET in relapsed colorectal cancer and the decision of reimbursement should base on published studies and on their level of evidence. Therefore, the PET-studies published between 1997 and 2002 were graded by the bias-criteria, by two rating-systems and by two classification-systems for the level of evidence according to AHCPR (Agency for Health Care Policy and Research) and VHA (Veterans Health Administration). Results: The recommendation for the use of PET in relapsed colorectal cancer reached the level IIa according to the AHCPR, corresponding to level B according to the VHA. The sensitivity and specificity of FDG-PET were 94% (95% CI: 91-96%) and 78% (95% CI: 69-86%), respectively. Staging was changed correctly in 27% of patients (95% CI: 24-30%). Staging by FDG-PET was incorrect in 4% of the patients (95% CI: 2-5%) compared with the conventionel methods. The additional use of PET changed the prospectively defined management plan for 34% of patients (95% CI: 31-38%). Either potentially curative operations were initiated in case of resectable tumour or futile operations were cancelled in case of multiple metastases. Conclusion: The 3-years-survival-rate following surgery would have exceeded 70% if the selection of patients had included an additional PET-examination. The correct selection of patients is requested in the daily routine as well as in the clinical implementation of neoadjuvant therapies to prevent a selection-bias from a suboptimal restaging without PET. (orig.)

  18. Axial anomaly in nonrenormalizable theories

    International Nuclear Information System (INIS)

    The anomaly for the axial current in nonrenormalizable theories with electromagnetic coupling is considered. The spinor electrodynamics with Pauli term is examined in detail using the Feynman graph technique and the point-splitting method. The same finite value for the axial anomaly emerges. (author)

  19. Positron Emission Tomography (PET) in the oncologic clinical practice; Tomografia por Emision de Positrones (PET) en la practica clinica oncologica

    Energy Technology Data Exchange (ETDEWEB)

    Serna M, J.A.; Luviano, C.; Martinez V, D. [Hospital Angeles del Pedregal Mexico DF (Mexico); Maldonado S, A. [Centro PET Complutense, Madrid (Spain)

    2005-07-01

    We intended to determine the frequency with that the computer axial tomography (TAC), it was able to visualize the lesions extra neoplasia detected by the PET tomography in patients with fully identified primary malignant neoplasia. (Author)

  20. Proto-I axial-focusing experiments

    International Nuclear Information System (INIS)

    The time-integrated axial (z) focus of the 4.5-cm-radius Proto I (1.5 MV, 500 kA) radial proton diode is presently limited to approx. 3 mm FWHM. This result is obtained with current neutralized beam transport in a gas cell with 6 Torr argon. If the vertical local divergence were the same (10 or less) as the horizontal divergence, the local divergence alone would produce a 1.5 mm FWHM focus. The axial focal size is evidently limited by time-dependent effects. These are studied by observing the beam incident upon various targets with two time-resolved pinhole cameras. The first camera observes Rutherford-scattered protons from gold targets with an array of 11 siicon PIN detectors. The second camera observes K/sub α/-fluorescence from aluminum targets with 4 independently-gated microchannel plates imaging tubes

  1. Extra-axial brain tumors.

    Science.gov (United States)

    Rapalino, Otto; Smirniotopoulos, James G

    2016-01-01

    Extra-axial brain tumors are the most common adult intracranial neoplasms and encompass a broad spectrum of pathologic subtypes. Meningiomas are the most common extra-axial brain tumor (approximately one-third of all intracranial neoplasms) and typically present as slowly growing dural-based masses. Benign meningiomas are very common, and may occasionally be difficult to differentiate from more aggressive subtypes (i.e., atypical or malignant varieties) or other dural-based masses with more aggressive biologic behavior (e.g., hemangiopericytoma or dural-based metastases). Many neoplasms that typically affect the brain parenchyma (intra-axial), such as gliomas, may also present with primary or secondary extra-axial involvement. This chapter provides a general and concise overview of the common types of extra-axial tumors and their typical imaging features. PMID:27432671

  2. Build Axial Gradient Field by Using Axial Magnetized Permanent Rings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

  3. Dissipative Axial Inflation

    CERN Document Server

    Notari, Alessio

    2016-01-01

    We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...

  4. Axial Patterning in Hydra

    Science.gov (United States)

    Bode, Hans R.

    2009-01-01

    Morphogen gradients play an important role in pattern formation during early stages of embryonic development in many bilaterians. In an adult hydra, axial patterning processes are constantly active because of the tissue dynamics in the adult. These processes include an organizer region in the head, which continuously produces and transmits two signals that are distributed in gradients down the body column. One signal sets up and maintains the head activation gradient, which is a morphogenetic gradient. This gradient confers the capacity of head formation on tissue of the body column, which takes place during bud formation, hydra's mode of asexual reproduction, as well as during head regeneration following bisection of the animal anywhere along the body column. The other signal sets up the head inhibition gradient, which prevents head formation, thereby restricting bud formation to the lower part of the body column in an adult hydra. Little is known about the molecular basis of the two gradients. In contrast, the canonical Wnt pathway plays a central role in setting up and maintaining the head organizer. PMID:20066073

  5. Atom probe tomography evidence for uniform incorporation of Bi across the growth front in GaAs1-xBix/GaAs superlattice

    Science.gov (United States)

    Chen, Weixin; Ronsheim, Paul A.; Wood, Adam W.; Forghani, Kamran; Guan, Yingxin; Kuech, Thomas F.; Babcock, Susan E.

    2016-07-01

    The three-dimensional distribution of Bi atoms in a GaAs1-xBix/GaAs superlattice grown by metalorganic vapor phase epitaxy (MOVPE) was studied using atom probe tomography (APT). The Bi distribution in the growth direction deduced from APT agreed quantitatively with the complex Bi concentration profile that was discovered using high-angle annular dark-field scanning transmission electron microscopy in a previous study. More importantly, APT revealed the Bi atom distribution in the growth planes at near atomic resolution. Bi nearest neighbor distribution and concentration frequency distribution analysis of the APT data indicated a statistically random distribution of Bi atoms in 1-2 nm thick layers oriented perpendicular to the growth direction. These results provide evidence that Bi is incorporated homogeneously across the growth front even when the concentration profile in the growth direction is complex. They also suggest that MOVPE growth conditions can promote uniform Bi distribution within GaAs1-xBix layers, opening a path for application of these materials in the optoelectronic devices for which they show much promise.

  6. The role of metabotropic glutamate receptor 5 in the pathogenesis of mood disorders and addiction:Combining preclinical evidence with human Positron Emission Tomography (PET studies

    Directory of Open Access Journals (Sweden)

    Sylvia eTerbeck

    2015-03-01

    Full Text Available In the present review, we deliver an overview of the involvement of metabotropic glutamate receptor 5 (mGluR5 activity and density in pathological anxiety, mood disorders and addiction. Specifically, we will describe mGluR5 studies in humans that employed Positron Emission Tomography (PET and combined the findings with preclinical animal research. This combined view of different methodological approaches — from basic neurobiological approaches to human studies — might give a more comprehensive and clinically relevant view of mGluR5 function in mental health than the view on preclinical data alone. We will also review the current research data on mGluR5 along the Research Domain Criteria (RDoC. Firstly, we found evidence of abnormal glutamate activity related to the positive and negative valence systems, which would suggest that antagonistic mGluR5 intervention has prominent anti-addictive, anti-depressive and anxiolytic effects. Secondly, there is evidence that mGluR5 plays in important role in systems for social functioning and the response to social stress. Finally, mGluR5’s important role in sleep homeostasis suggests that this glutamate receptor may play an important role in RDoC’s arousal and modulatory systems domain. Glutamate was previously mostly investigate in non-human studies, however initial human clinical PET research now also supports the hypothesis that, by mediating brain excitability, neuroplasticity and social cognition, abnormal metabotropic glutamate activity might predispose individuals to a broad range of psychiatric problems.

  7. Computerized Tomography

    International Nuclear Information System (INIS)

    The physical bases of computerized tomography are presented, the following items being discussed:attenuation of a photon beam by an absorbent material, reconstruction algorithms and detection systems. Image statistics is also presented. The emission computerized tomography is discussed. Clinical results of computerized tomography are presented. (M.A.)

  8. Study of axial magnetic effect

    International Nuclear Information System (INIS)

    The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T2 behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction

  9. Characterization of Multiflux Axial Compressors

    International Nuclear Information System (INIS)

    In the present work the results of analytical models of performance are compared with experimental data acquired in the multi flux axial compressor test facility, built in The Pilcaniyeu Technological Complex for the SIGMA project.We describe the experimental circuit and the data of the dispersion inside the axial compressor obtained using a tracer gas through one of the annular inlets.The attained results can be used to validate the design code for the multi flux axial compressors and SIGMA industrial plant

  10. Axial gap rotating electrical machine

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-02-23

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

  11. Fe-implanted 6H-SiC: Direct evidence of Fe{sub 3}Si nanoparticles observed by atom probe tomography and {sup 57}Fe Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, M. L.; Fnidiki, A., E-mail: abdeslem.fnidiki@univ-rouen.fr; Lardé, R.; Cuvilly, F.; Blum, I. [Groupe de Physique des Matériaux, Université et INSA de Rouen - UMR CNRS 6634 - Normandie Université. F-76801 Saint Etienne du Rouvray (France); Lechevallier, L. [Groupe de Physique des Matériaux, Université et INSA de Rouen - UMR CNRS 6634 - Normandie Université. F-76801 Saint Etienne du Rouvray (France); Département de GEII, Université de Cergy-Pontoise, rue d' Eragny, Neuville sur Oise, 95031 Cergy-Pontoise (France); Debelle, A.; Thomé, L. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), CNRS-IN2P3-Univ. Paris-Sud 11, Bât. 108, 91405 Orsay (France); Viret, M. [Service de Physique de l' Etat Condensé (DSM/IRAMIS/SPEC), UMR 3680 CNRS, Bât. 772, Orme des Merisiers, CEA Saclay 91191 Gif sur Yvette (France); Marteau, M.; Eyidi, D.; Declémy, A. [Institut PPRIME, UPR 3346 CNRS, Université de Poitiers, ENSMA, SP2MI, téléport 2, 11 Bvd M. et P. Curie 86962 Futuroscope, Chasseneuil (France)

    2015-05-14

    In order to understand ferromagnetic ordering in SiC-based diluted magnetic semiconductors, Fe-implanted 6H-SiC subsequently annealed was studied by Atom Probe Tomography, {sup 57}Fe Mössbauer spectroscopy and SQUID magnetometry. Thanks to its 3D imaging capabilities at the atomic scale, Atom Probe Tomography appears as the most suitable technique to investigate the Fe distribution in the 6H-SiC host semiconductor and to evidence secondary phases. This study definitely evidences the formation of Fe{sub 3}Si nano-sized clusters after annealing. These clusters are unambiguously responsible for the main part of the magnetic properties observed in the annealed samples.

  12. Chest computed tomography

    DEFF Research Database (Denmark)

    Loeve, Martine; Krestin, Gabriel P.; Rosenfeld, Margaret;

    2013-01-01

    are not suitable to study CF lung disease in young children. Chest computed tomography (CT) holds great promise for use as a sensitive surrogate endpoint in CF. A large body of evidence has been produced to validate the use of chest CT as primary endpoint to study CF lung disease. However, before...

  13. Vectorial versus axial goldstone bosons

    International Nuclear Information System (INIS)

    The Yukawa interactions of fermions with Goldstone bosons are given in closed form for an arbitrary renormalizable field theory to all orders of perturbation theory or for a general effective Lagrangian. Although the diagonal couplings are always pseudoscalar there is an important difference between spontaneously broken vector and axial-vector global symmetries. Compared to the axial case, the diagonal douplings of 'vectorial' Goldstone bosons to charged fermions are suppressed by mixing angles or appear only via radiative corrections involving gauge fields. This general result may be relevant for the problem of flavour symmetry breaking in composite models. (Author)

  14. Simulation of an Axial Vircator

    CERN Document Server

    Tikhomirov, V V

    2013-01-01

    An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly generalized to the case of axially nonsymmetric modes, while the parameters of these correction methods can be widely used to improve an agreement between the simulation predictions and the experimental data.

  15. Axial structure of the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner

    2002-01-01

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

  16. Amplified Dispersive Optical Tomography

    CERN Document Server

    Goda, Keisuke; Jalali, Bahram

    2008-01-01

    Optical coherence tomography (OCT) has proven to be a powerful technique for studying tissue morphology in ophthalmology, cardiology, and endomicroscopy. Its performance is limited by the fundamental trade-off between the imaging sensitivity and acquisition speed -- a predicament common in virtually all imaging systems. In this paper, we circumvent this limit by using distributed Raman post-amplification of the reflection from the sample. We combine the amplification with simultaneously performed dispersive Fourier transformation, a process that maps the optical spectrum into an easily measured time-domain waveform. The Raman amplification enables measurement of weak signals which are otherwise buried in noise. It extends the depth range without sacrificing the acquisition speed or causing damage to the sample. As proof of concept, single-shot imaging with 15 dB improvement in sensitivity at an axial scan rate of 36.6 MHz is demonstrated.

  17. Positron emission tomography/computed tomography.

    Science.gov (United States)

    Townsend, David W

    2008-05-01

    Accurate anatomical localization of functional abnormalities obtained with the use of positron emission tomography (PET) is known to be problematic. Although tracers such as (18)F-fluorodeoxyglucose ((18)F-FDG) visualize certain normal anatomical structures, the spatial resolution is generally inadequate for accurate anatomic localization of pathology. Combining PET with a high-resolution anatomical imaging modality such as computed tomography (CT) can resolve the localization issue as long as the images from the two modalities are accurately coregistered. However, software-based registration techniques have difficulty accounting for differences in patient positioning and involuntary movement of internal organs, often necessitating labor-intensive nonlinear mapping that may not converge to a satisfactory result. Acquiring both CT and PET images in the same scanner obviates the need for software registration and routinely provides accurately aligned images of anatomy and function in a single scan. A CT scanner positioned in line with a PET scanner and with a common patient couch and operating console has provided a practical solution to anatomical and functional image registration. Axial translation of the couch between the 2 modalities enables both CT and PET data to be acquired during a single imaging session. In addition, the CT images can be used to generate essentially noiseless attenuation correction factors for the PET emission data. By minimizing patient movement between the CT and PET scans and accounting for the axial separation of the two modalities, accurately registered anatomical and functional images can be obtained. Since the introduction of the first PET/CT prototype more than 6 years ago, numerous patients with cancer have been scanned on commercial PET/CT devices worldwide. The commercial designs feature multidetector spiral CT and high-performance PET components. Experience has demonstrated an increased level of accuracy and confidence in the

  18. Axially symmetric rotating traversable wormholes

    CERN Document Server

    Kuhfittig, P K F

    2003-01-01

    This paper generalizes the static and spherically symmetric traversable wormhole geometry to a rotating axially symmetric one with a time-dependent angular velocity by means of an exact solution. It was found that the violation of the weak energy condition, although unavoidable, is considerably less severe than in the static spherically symmetric case. The radial tidal constraint is more easily met due to the rotation. Similar improvements are seen in one of the lateral tidal constraints. The magnitude of the angular velocity may have little effect on the weak energy condition violation for an axially symmetric wormhole. For a spherically symmetric one, however, the violation becomes less severe with increasing angular velocity. The time rate of change of the angular velocity, on the other hand, was found to have no effect at all. Finally, the angular velocity must depend only on the radial coordinate, confirming an earlier result.

  19. View of the Axial Field Spectrometer

    CERN Multimedia

    1980-01-01

    The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.

  20. Simulation of an Axial Vircator

    OpenAIRE

    Tikhomirov, V. V.; Siahlo, S. E.

    2013-01-01

    An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly gene...

  1. Progress in computerized body tomography

    International Nuclear Information System (INIS)

    Since computerized tomography of the head has become well-established as a most important diagnostic tool in medicine, technical advance and scientific investigation has centered on CT of the remainder of the body. A proliferation of scientific papers covering many aspects of body scanning has occured, but the evidence is only slowly emerging to establish the indications, advantages, and cost effectiveness of computerized tomography below the head. An appraisal of the present status of computerized body tomography from viewpoint of the clinical radiologist is presented. 1977 planning recommendations for the western United States are cited. (orig.) 891 MG/orig. 892 MB

  2. Transverse tomography and radiotherapy

    International Nuclear Information System (INIS)

    This study was intended to delineate the indications for radiotherapy treatment-planning with the help of computerized axial tomography (C.T.) and transverse analog tomography (T.A.T.). Radiotherapy localisation procedures with the conventional method (simulator), with the CT-scanner and with the transverse analog tomograph (T.A.T., Simtomix, Oldelft) were compared. As criterium for evaluation differences in reconstruction drawing based on these methods were used. A certain method was judged ''superior'' to another if the delineation of the target volume was more accurate, if a better impression was gained of the site of (for irradiation) organs at risk, or if the localisation could only be performed with that method. The selected group of patients consisted of 120 patients for whom a reconstruction drawing in the transverse plane was made according to the treatment philosophy. In this group CT-assisted localisation was judged on 68 occasions superior to the conventional method. In a number of cases it was found that a ''standard'' change in a standard target volume, on the base of augmented anatomical knowledge, made the conventional method sufficient. The use of CT-scanner for treatment planning was estimated. For ca. 270/1000 new patients a CT-scan is helpful (diagnostic scan), for 140 of them the scan is necessary (planning scan). The quality of the anatomical information obtained with the T.A.T. does not yet fall within acceptable limits, but progress has been made. (Auth.)

  3. Axial Force at the Vessel Bottom Induced by Axial Impellers

    OpenAIRE

    I. Fořt; P. Hasal; A. Paglianti; F. Magelli

    2008-01-01

    This paper deals with the axial force affecting the flat bottom of a cylindrical stirred vessel. The vessel is equipped with four radial baffles and is stirred with a four 45° pitched blade impeller pumping downwards. The set of pressure transducers is located along the whole radius of the flat bottom between two radial baffles. The radial distribution of the dynamic pressures indicated by the transducers is measured in dependence on the impeller off-bottom clearance and impeller speed.It fol...

  4. Facility for positron computed tomography

    International Nuclear Information System (INIS)

    For positron computed tomography two or more rings of scintillation detectors are used by which three or more sections of the object may be determined at a time. The rings are placed in parallel planes having got some distance from each other, axially movable collimator rings being provided for. Each collimator can be moved towards the opposite collimator and towards a central collimator which also is ring-shaped and is placed between the rows of detectors. The external and internal collimator are used for data selection and image-forming. (DG)

  5. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Sinuses What is CT (Computed Tomography) of ... of CT of the Sinuses? What is CT (Computed Tomography) of the Sinuses? Computed tomography, more commonly known ...

  6. Computed Tomography (CT) -- Sinuses

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Sinuses Computed tomography (CT) of the sinuses ... CT of the Sinuses? What is CT (Computed Tomography) of the Sinuses? Computed tomography, more commonly known ...

  7. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available ... Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Sinuses Computed tomography (CT) of the sinuses ... CT of the Sinuses? What is CT (Computed Tomography) of the Sinuses? Computed tomography, more commonly known ...

  8. Strange axial-vector mesons

    International Nuclear Information System (INIS)

    The strange axial-vector mesons K1 (1270) and K1 (1400) are reanalyzed in the light of the updated experimental information and compared with the recent result on the Kππ production in τ decay. The mixing angle between the strange mesons of 3P1 and 1P1 is determined by the partial decay rates, and, independently, by the masses. They lead to θK∼33 degree or 57 degree. The observed K1 (1400) production dominance in the τ decay favors θK∼33 degree. Flavor-SU(3) breaking of 20% or so in the production amplitudes can explain quantitatively the observed production ratio

  9. Neutron tomography

    International Nuclear Information System (INIS)

    In this paper a survey is given of recent developments in selected areas of neutron tomography, within the context of several applications Argonne is involved in, including high penetration of reactor-fuel bundles in thick containers (involving TREAT and NRAD facilities), dual-energy hydrogen imaging (performed at IPNS), dynamic coarse-resolution emission tomography of rector fuel under test (a proposed modification to the TREAT hodoscope), and an associated-particle system that uses neutron flight-time to electronically collimate transmitted neutrons and to tomographically image nuclides identified by reaction gamma-rays

  10. PWR AXIAL BURNUP PROFILE ANALYSIS

    International Nuclear Information System (INIS)

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

  11. PWR AXIAL BURNUP PROFILE ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    J.M. Acaglione

    2003-09-17

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

  12. Seismic Tomography.

    Science.gov (United States)

    Anderson, Don L.; Dziewonski, Adam M.

    1984-01-01

    Describes how seismic tomography is used to analyze the waves produced by earthquakes. The information obtained from the procedure can then be used to map the earth's mantle in three dimensions. The resulting maps are then studied to determine such information as the convective flow that propels the crustal plates. (JN)

  13. Mass Effect on Axial Charge Dynamics

    CERN Document Server

    Guo, Er-dong

    2016-01-01

    We studied effect of finite quark mass on the dynamics of axial charge using the D3/D7 model in holography. The mass term in axial anomaly equation affects both the fluctuation (generation) and dissipation of axial charge. We studied the dependence of the effect on quark mass and external magnetic field. For axial charge generation, we calculated the mass diffusion rate, which characterizes the helicity flipping rate. The rate is a non-monotonous function of mass and can be significantly enhanced by the magnetic field. The diffusive behavior is also related to a divergent susceptibility of axial charge. For axial charge dissipation, we found that in the long time limit, the mass term dissipates all the charge effectively generated by parallel electric and magnetic fields. The result is consistent with a relaxation time approximation. The rate of dissipation through mass term is a monotonous increasing function of both quark mass and magnetic field.

  14. Axial Vector $Z'$ and Anomaly Cancellation

    CERN Document Server

    Ismail, Ahmed; Tsao, Kuo-Hsing; Unwin, James

    2016-01-01

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

  15. Computed tomography of the spine

    International Nuclear Information System (INIS)

    Until the advent of Computed Tomography (CT), axial studies of the spine were limited in the main to gross bony anatomy and to conventional transaxial tomography (TAT). Others studied the upper cervical cord in transverse section during gas myelography and encephalography. The potential role of CT in the evaluation of spinal anatomy and disease was recognized, however, at an early stage in the development of the general purpose CT scanner. CT is not organ specific and therefore provides a uniformly thin (1.5-13 mm) axial section displaying detailed spinal topographical anatomy against a background of paravertebral muscles, vascular structures and body cavity organs. The relationships of the apophyseal joints to the spinal canal and intervertebral foramina are particularly well displayed. The study of neural tissue and pathology within the spinal canal is facilitated by the use of a non-ionic water-soluble contrast medium (viz. metrizamide) in the subarachnoid spaces. The high sensitivity of CT to very small changes in X-ray attenuation permits studies to be continued over several hours. The digital derivation of the sequential CT transaxial sections enables not only interrogation of data and quantitative studies to be made but also makes possible computer-generated reconstructions in other planes

  16. Axial velocity in decaying swirl flow

    Science.gov (United States)

    Algifri, A. H.; Bhardwaj, R. K.; Rao, Y. V. N.

    1988-09-01

    Experiments were carried out on turbulent swirling flow with variable initial swirl at different flow rates to study the effect of swirl on axial velocity. A correlation was made between the defect in the swirling flow axial velocity and the swirl number which locally defines the swirl intensity. An expression which can be used to predict the axial velocity distribution of turbulent swirling flow in a pipe is presented.

  17. Sensorless Control of Axial Magnetic Bearings

    Science.gov (United States)

    Atsumo, Daichi; Yoshida, Toshiya; Ohniwa, Katsumi

    This paper describes a sensorless control method of axial active magnetic bearings (AMBs). At high frequencies, inductance of the axial electromagnets is hardly dependent on the airgap because of the eddy current effects of the non-laminated core. Therefore the carrier frequency should be 3 kHz below to improve the sensitivity to the airgap. In the experiment, Sensorless controll of the axial AMBs have been achieved.

  18. Axial asymmetry in the IVBM

    International Nuclear Information System (INIS)

    The dynamical symmetry limit of the two-fluid Interacting Vector Boson Model (IVBM), defined through the chain Sp(12,R) contains U(3,3) contains Up(3) x Un(3) contains SU*(3) contains SO(3), is considered and applied for the description of nuclear collective spectra exhibiting axially asymmetric features. The effect of the introduction of a Majorana interaction to the SU*(3) model Hamiltonian on the γ-band energies is studied. The theoretical predictions are compared with the experimental data for 192Os, 190Os, and 112Ru isotopes. It is shown that by taking into account the full symplectic structures in the considered dynamical symmetry of the IVBM, the proper description of the energy spectra and the γ-band energy staggering of the nuclei under considerations can be achieved. The obtained results show that the potential energy surfaces for the following two nuclei 192Os and 112Ru, possess almost γ-flat potentials with very shallow triaxial minima, suggesting a more complex and intermediate situation between γ-rigid and γ-unstable structures. Additionally, the absolute B(E2) intraband transition probabilities between the states of the ground-state band and γ band, as well as the B(M1) interband transition probabilities between the states of the ground and γ bands for the two nuclei 192Os and 190Os are calculated and compared with experiment and for the B(E2) values with the predictions of some other collective models incorporating the γ-rigid or γ-unstable structures. The obtained results agree well with the experimental data and reveal the relevance of the used dynamical symmetry of IVBM in the description of nuclei exhibiting axially asymmetric features in their spectra. (orig.)

  19. Effective quantum number for axially symmetric problems

    OpenAIRE

    Trunov, N. N.

    2014-01-01

    We generalize the universal effective quantum number introduced earlier for centrally symmetric problems. The proposed number determines the semiclassical quantization condition for axially symmetric potentials.

  20. Origin of axial current in scyllac

    International Nuclear Information System (INIS)

    The origin of the axial current observed in Scyllac (a high beta stellarator experiment) is discussed. A shaped coil and/or helical winding produce rotational transform which links magnetic lines of force to the plasma column and the axial current is induced electromagnetically. This phenomenon is inherent in a pulsed high-beta stellarator. The rotational transform produced by the induced axial current is much smaller than that associated with the l = 1, 0 equilibrium fields. The effect of the axial current on the equilibrium and stability of the plasma column is thus small. It is also shown that the magnetic field shear near a plasma surface is very strong

  1. 3D SPIRAL COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF AN ABDOMINAL TUMOUR

    OpenAIRE

    R.C. Tiutiuca; Iuliana Eva

    2006-01-01

    Patients with digestive illnesses requires a full exploration, cases where imagistic assets support (echographic examination, radiological data, computed tomography, magnetic resonance) are very usefully. Computed tomography, in this process, has a special value. The results from axial images are sustained by the informations supplied from three-dimensional reconstruction processes (3D reconstruction) with relevant importance in establishment of diagnosis and therapeutic plan.

  2. Computerized tomography

    Energy Technology Data Exchange (ETDEWEB)

    Caille, J.M.; Salamon, G.

    1980-01-01

    As X-ray CT becomes more commonplace, other techniques of investigation using roughly comparable hardware and software have appeared. Positron-Emission Tomography already provides indispensable physiological and physio-pathological information. Similarly, in the histo-chemical field, Nuclear Magnetic Resonance seems very promising. Some of these new techniques will no doubt shortly be considered as essential as CT in establishing accurate diagnoses non-invasively.

  3. Computerized tomography

    International Nuclear Information System (INIS)

    As X-ray Ct becomes more commonplace, other techniques of investigation using roughly comparable hardware and software have appeared. Positron-Emission Tomography already provides indispensable physiological and physio-pathological information. Similarly, in the histo-chemical field, Nuclear Magnetic Resonance seems very promising. Some of these new techniques will no doubt shortly be considered as essential as CT in establishing accurate diagnoses non-invasively. (orig./VJ)

  4. Color Tomography

    CERN Document Server

    Jain, B; Takada, M; Jain, Bhuvnesh; Connolly, Andrew; Takada, Masahiro

    2006-01-01

    Lensing tomography with multi-color imaging surveys can probe dark energy and the cosmological power spectrum. However accurate photometric redshifts for tomography out to high redshift require imaging in five or more bands, which is expensive to carry out over thousands of square degrees. Since lensing makes coarse, statistical use of redshift information, we explore the prospects for tomography using limited color information from two or three band imaging. With an appropriate calibration sample, we find that it is feasible to create up to four redshift bins using imaging data in just the g, r and i bands. We construct such redshift sub-samples from mock catalogs by clustering galaxies in color space and discarding regions with poorly-defined redshift distributions. The loss of galaxy number density decreases the accuracy of lensing measurements, but even losing half or more of the galaxies is not a severe loss for large area surveys. We estimate the errors on lensing power spectra and dark energy parameter...

  5. Evidence for a low permeability fluid trap in the Nový Kostel Seismic Zone, Czech Republic, using double-difference tomography

    Science.gov (United States)

    Alexandrakis, C.; Calo, M.; Vavrycuk, V.

    2012-12-01

    The West Bohemia/Vogtland region is the border area between the Czech Republic and Germany known for frequent occurrences of earthquake swarms. The most prominent earthquake swarms occurred recently in 1985/86, 1997, 2000 (Fischer and Horálek, 2003) and 2008 (Fischer et al., 2010). They comprised thousands of microearthquakes, their duration was between 2 weeks to 2 months, and the activity focused typically at depths ranging from 7 to 12 km. The seismic activity is concentrated mostly at the same epicentral area, called the Nový Kostel Zone. This zone is located on the edge of the Cheb Basin, Eger Rift, and at the junction of the Mariánské-Lázně Fault with the Počátky-Plesná Shear Zone. Numerous gas vents and mineral springs within and around the Cheb Basin indicate that uprising magmatic fluids may act as a swarm trigger. In this study, we apply double-difference tomography to investigate the structure within and around the Nový Kostel focal zone. We use data from the 2008 earthquake swarm, as it has been extensively analyzed, and focal mechanisms, principal faults, tectonic stress, source migration and other basic characteristics are known. We selected about 500 microearthquakes recorded at 22 local seismic stations of the West Bohemia Network (WEBNET). The events were inverted for the 3-D seismic structure using the TomoDD code (Zhang and Thurber, 2003) and post-processed using the Weighted Average Model method (Calò et al., 2011). The application of double-difference tomography is advantageous for this setting as swarm foci are closely spaced and form a dense cluster. The geometry of the focal zone and the WEBNET network configuration offer good raypath coverage in all directions. Applying double-difference tomography we produce and interpret 3-D models of the P and S velocities. In this work, we interpret 3-D models of the P velocity and P-to-S ratio in and around the focal zone. The P-to-S model was obtained by calculating directly the ratio

  6. Investigation of Valve Plate in Water Hydraulic Axial Piston Motor

    Institute of Scientific and Technical Information of China (English)

    聂松林; 李壮云; 等

    2002-01-01

    This paper has introduced the developments of water hydraulic axial piston equipments.According to the effects of physicochemical properties of water on water hydraulic components,a novel valve plate for water hydraulic axial motor has been put forward,whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely.The material screening experiment of valve plate is done on the test rig.Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied.The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively.It is evident that the appropriate structure should change the wear status between matching paris and reduces the wear and specific pressure of the matching pairs.The specimen with the new type valve plate is used in a tool system.

  7. The Sex and Race Specific Relationship between Anthropometry and Body Fat Composition Determined from Computed Tomography: Evidence from the Multi-Ethnic Study of Atherosclerosis.

    Directory of Open Access Journals (Sweden)

    Morgana Mongraw-Chaffin

    Full Text Available Few studies have investigated the relationship of anthropometric measurements with computed tomography (CT body fat composition, and even fewer determined if these relationships differ by sex and race.CT scans from 1,851 participants in the population based Multi-Ethnic Study of Atherosclerosis were assessed for visceral and subcutaneous fat areas by semi-automated segmentation of body compartments. Regression models were used to investigate relationships for anthropometry with visceral and subcutaneous fat separately by sex and race/ethnicity.Participants were 50% female, 41% Caucasian, 13% Asian, 21% African American, and 25% Hispanic. For visceral fat, the positive relationship with weight (p = 0.028, waist circumference (p<0.001, waist to hip ratio (p<0.001, and waist to height ratio (p = 0.05 differed by sex, with a steeper slope for men. That is, across the range of these anthropometric measures the rise in visceral fat is faster for men than for women. Additionally, there were differences by race/ethnicity in the relationship with height (p<0.001, weight (p<0.001, waist circumference (p<0.001, hip circumference (p = 0.006, and waist to hip ratio (p = 0.001 with the Hispanic group having shallower slopes. For subcutaneous fat, interaction by sex was found for all anthropometric indices at p<0.05, but not for race/ethnicity.The relationship between anthropometry and underlying adiposity differs by sex and race/ethnicity. When anthropometry is used as a proxy for visceral fat in research, sex-specific models should be used.

  8. More evidence for the red-shift dependence of colour from the Joint Light-curve Analysis supernova sample using red-shift tomography

    Science.gov (United States)

    Li, Miao; Li, Nan; Wang, Shuang; Zhou, Lanjun

    2016-08-01

    In this work, by applying the red-shift tomography method to the Joint Light-curve Analysis (JLA) supernova sample, we explore the possible red-shift dependence of the stretch luminosity α and the colour luminosity β. The basic idea is to divide the JLA sample into different red-shift bins, assuming that α and β are piecewise constants. Then, by constraining the ΛCDM model, we check the consistency of the cosmology-fitting results given by the supernova sample of each red-shift bin. We also adopt the same technique to explore the possible evolution of β in various subsamples of JLA. Using the full JLA data, we find that α is always consistent with a constant value. In contrast, at high red shift, β has a significant trend of decreasing, at ˜3.5σ confidence level (CL). Moreover, we find that the low-z subsample favours a constant β; in contrast, the Sloan Digital Sky Survey and Supernova Legacy Survey subsamples favour a decreasing β at 2σ and 3.3σ CL, respectively. Besides, by using a binned parametrization of β, we study the impact of the evolution of β on parameter estimation. We find that compared with a constant β, a varying β yields a larger best-fitting value of fractional matter density Ωm0, which slightly deviates from the best-fitting result given by other cosmological observations. However, for both the varying β and the constant β cases, the 1σ regions of Ωm0 are still consistent with the result given by other observations.

  9. Spinal computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Sartor, K.

    1980-10-01

    Computed tomography (CT) of the spine and spinal cord is gaining more and more importance as a valuable investigative method in neuroradiology. Performed as a noninvasive procedure, with or without intravenous contrast enhancement, it can be used to diagnose paravertebral soft tissue lesions, constrictive lesions of the bony spinal canal, structure changes of the vertebral column or of individual vertebrae, vascular intraspinal lesions, and intraspinal tumors with abnormally high or abnormally low attenuation values. Performed as an invasive procedure, after intrathecal introduction of metrizamide, spinal CT can in selected cases be used in conjunction with conventional metrizamide myelography as an additional procedure (secondary CT-myelography) or even as initial procedure ( primary CT-myelography), taking advantage of its unique properties, namely to provide a transverse axial image of the spine and related soft tissue structures and to detect even small differences in density. Further improvement of spinal CT, particularly the routine non-invasive demonstration of the intraspinal soft tissues, is to be expected.

  10. Optical Coherence Tomography

    Science.gov (United States)

    ... Cardiac Magnetic Resonance Imaging (MRI and MRA) Computed Tomography (CT) Scan Diagnostic Tests and Procedures Echocardiography Electrocardiogram ... Ultrasound Nuclear Stress Test Nuclear Ventriculography Positron Emission Tomography (PET) Stress ... Optical Coherence Tomography | ...

  11. Computed Tomography (CT) -- Head

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Head Computed tomography (CT) of the head uses special x-ray ... What is CT Scanning of the Head? Computed tomography, more commonly known as a CT or CAT ...

  12. Computerized tomography

    International Nuclear Information System (INIS)

    A brief outline of the history and the medical significance of computerized tomography is followed by a summary description of the principles involved, indicating the essential features of the technique: X-ray transradiation only of the slice of the body of interest, distorsion-correcting image reconstruction, digital-electronic data acquisition and processing. A comparison between computerized tomography and the conventional X-ray techniques first draws attention to what they have in common, and then takes a look at the main differences: substitution image instead of superposition image, scarcely varying dose distribution throughout the whole cross-section of the patient in place of a marked drop in dose from the radiation entry side to the radiation exit side, a mathematically reconstructed instead of a natural-physical image, and motion artefacts instead of kinetic blurring. With respect to the state of the art of the technology, the different forms of the radiation/detector system of the types of equipment available, together with the possible effects on the characteristic features of the image produced, are discussed. Image evaluation and image filing are briefly considered. The concluding look at the tendencies in the field of development presents a breakdown of these latter with regard to the general properties of the system, component technology and the opening up of new applications. (orig.)

  13. Terahertz Computed Tomography of NASA Thermal Protection System Materials

    Science.gov (United States)

    Roth, D. J.; Reyes-Rodriguez, S.; Zimdars, D. A.; Rauser, R. W.; Ussery, W. W.

    2011-01-01

    A terahertz axial computed tomography system has been developed that uses time domain measurements in order to form cross-sectional image slices and three-dimensional volume renderings of terahertz-transparent materials. The system can inspect samples as large as 0.0283 cubic meters (1 cubic foot) with no safety concerns as for x-ray computed tomography. In this study, the system is evaluated for its ability to detect and characterize flat bottom holes, drilled holes, and embedded voids in foam materials utilized as thermal protection on the external fuel tanks for the Space Shuttle. X-ray micro-computed tomography was also performed on the samples to compare against the terahertz computed tomography results and better define embedded voids. Limits of detectability based on depth and size for the samples used in this study are loosely defined. Image sharpness and morphology characterization ability for terahertz computed tomography are qualitatively described.

  14. Axial force measurement for esophageal function testing.

    Science.gov (United States)

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

    2009-01-14

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

  15. Axial force measurement for esophageal function testing

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

  16. Axial length variability in cataract surgery

    International Nuclear Information System (INIS)

    To determine the mean axial length and biometric measures in patients undergoing cataract surgery and further compare the variability of axial length between the gender and with age. Study Design: Cross-sectional observational study. Place and Duration of Study: Eye Unit I, Department of Ophthalmology, Liaquat University of Medical and Health Sciences, Hyderabad, Pakistan from January 2010 to December 2012. Methodology: All patients referred for cataract surgery were assessed. The study included 886 eyes which were straightforward cataract cases with no other ocular problem. The data was collected for axial length, keratometric values and Intra-Ocular Lens (IOL) power prior to cataract surgery. The collected data was then analyzed using SPSS version 19 for windows software. Results: Gender based comparison showed significant difference in age, axial length, keratometric values and IOL power between the two groups (p=0.000). 86% of the eyes had an axial length between 21.00 mm and 23.99 mm. In univariate analysis there was significant (p=0.000) relation between overall age and axial length. The keratometric values ranged between 36.75 D and 52.50 D. Majority of the IOL powers ranged between 20.00 D and 23.00 D. Conclusion: The mean axial length of patients undergoing cataract surgery was 22.96 +- 1.04 mm, was comparable to Indian and Chinese population but shorter than the Western population. Females had shorter axial lengths, similar to other studies. Axial length was positively associated with age among the females, the cause of which is yet to be determined. (author)

  17. New Anomaly of the Axial-Vector Current

    Institute of Scientific and Technical Information of China (English)

    HE Han-Xin

    2001-01-01

    By computing the axial-vector current operator equation, we find the anomalous axial-vector curl equation besides the well-known anomalous axial-vector divergence equation (the Adler-Bell-Jackiw anomaly) and discuss its implication.``

  18. ASAS classification criteria for axial spondyloarthritis: time to modify.

    Science.gov (United States)

    Akkoc, Nurullah; Khan, Muhammad A

    2016-06-01

    The relationship between ankylosing spondylitis and the recently proposed entity called axial spondyloarthritis with its radiographic and non-radiographic forms that have been defined by the Assessment of Spondyloarthritis International Society (ASAS) criteria for axial spondyloarthritis (axSpA), is currently being debated. The Food and Drug Agency (FDA) had criticized the ASAS criteria and the studies which used these criteria to enroll patients in a clinical trial of certolizumab and adalimumab for the treatment of non-radiographic axial spondyloarthritis. The primary aim of classification criteria is to create homogenous patient populations for basic and clinical research. But the multi-arm construct of the ASAS criteria is a potential source of heterogeneity reducing their utility. Criteria sets should be regarded as dynamic concepts open to modifications or updates as our knowledge advances. We provide evidence to conclude that it is time to modify the ASAS Criteria for axSpA, and we propose some of the steps that can be taken to start moving forward in improving the validity of these criteria. PMID:27094940

  19. Computerised tomography

    International Nuclear Information System (INIS)

    Ever since the initial development of cranial computerised tomography (CT) it has been anticipated that this technique would make a substantial impact on the diagnosis, staging, treatment and follow-up of various malignancies. When whole-body CT machines became available in the mid 1970s, this hope started to be fulfilled - despite the fact that the images obtained by these early models were somewhat primitive compared with the high-resolution images produced by modern scanners. Now that such modern scanners are quite widely available within the UK, a rational outline of some of the uses of body CT in oncological practice can be considered. A few technical and procedural points are considered first and then some of the clinical problems in which CT has a role are discussed

  20. Axial Thermal Rotation of Slender Rods

    Science.gov (United States)

    Li, Dichuan; Fakhri, Nikta; Pasquali, Matteo; Biswal, Sibani Lisa

    2011-05-01

    Axial rotational diffusion of rodlike polymers is important in processes such as microtubule filament sliding and flagella beating. By imaging the motion of small kinks along the backbone of chains of DNA-linked colloids, we produce a direct and systematic measurement of axial rotational diffusivity of rods both in bulk solution and near a wall. The measured diffusivities decrease linearly with the chain length, irrespective of the distance from a wall, in agreement with slender-body hydrodynamics theory. Moreover, the presence of small kinks does not affect the chain’s axial diffusivity. Our system and measurements provide insights into fundamental axial diffusion processes of slender objects, which encompass a wide range of entities including biological filaments and linear polymer chains.

  1. SU(3)--Breaking Effects in Axial--Vector Couplings of Octet Baryons

    CERN Document Server

    Gensini, P M; Gensini, Paolo M.; Violini, Galileo

    1993-01-01

    Present evidence on baryon axial--vector couplings is reviewed, the main emphasis being on internal consistency between asymmetry and rate data. A complete account of all {\\sl small} terms in the Standard Model description of these latter leads to {\\sl both} consistency {\\sl and} evidence for breaking of flavour SU(3) in the axial couplings of octet baryons. Talk presented at "5th Int. Sympos. on Meson--Nucleon Physics and the Structure of the Nucleon", Boulder, CO, sept. 1993. To be published in $\\pi N$ Newsletter.

  2. Nonperturbative features of the axial current

    CERN Document Server

    Kopeliovich, B Z; Siddikov, M

    2013-01-01

    In this paper we study the nonperturbative structure of the axial current and evaluate the two-point distribution amplitudes $\\int d\\xi\\, e^{-iq...\\xi}$ in the framework of the instanton vacuum model in the leading order in $\\mathcal{O}(N_{c})$. We perform a direct numerical test of the relations between the axial current and the pion distribution amplitudes, imposed by PCAC, and found excellent agreement.

  3. Axial Vircator for Electronic Warfare Applications

    OpenAIRE

    L. Drazan; R. Vrana

    2009-01-01

    This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM) is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered b...

  4. Nonperturbative Aspects of Axial Vector Vertex

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang

    2002-01-01

    It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.

  5. An Unbroken Axial Vector Current Conservation Law

    CERN Document Server

    Sharafiddinov, Rasulkhozha S

    2015-01-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space i...

  6. Computed tomography in sport injuries

    International Nuclear Information System (INIS)

    Computed tomography (CT) provides axial slices plane and shows excellent details of bones and different soft tissues, favoring its use in traumatic lesions caused by sporting activities. Complex anatomical structures such as the shoulder, the vertebral column, the pelvis, the knee, the tarsal and carpal bones are often better recognized in detail than by conventional radiography. Fracture lines, localization of bone fragments and involvement of soft tissues are clearly demonstrated. Luxations and bone changes leading to luxations can be shown. CT arthrography provides for the first time a direct visualization of joint cartilage and of cruciate ligaments in the knee joint, so traumatic lesions such as chondropathia patellae or rupture of the cruciate ligaments are shown with a high degree of reliability. (orig.)

  7. Diffraction tomography with Fourier ptychography

    CERN Document Server

    Horstmeyer, Roarke

    2015-01-01

    This article presents a method to perform diffraction tomography in a standard microscope that includes an LED array for illumination. After acquiring a sequence of intensity-only images of a thick sample, a ptychography-based reconstruction algorithm solves for its unknown complex index of refraction across three dimensions. The experimental microscope demonstrates a spatial resolution of 0.39 $\\mu$m and an axial resolution of 3.7 $\\mu$m at the Nyquist-Shannon sampling limit (0.54 $\\mu$m and 5.0 $\\mu$m at the Sparrow limit, respectively), across a total imaging volume of 2.2 mm $\\times$ 2.2 mm $\\times$ 110 $\\mu$m. Unlike competing methods, the 3D tomograms presented in this article are continuous, quantitative, and formed without the need for interferometry or any moving parts. Wide field-of-view reconstructions of thick biological specimens demonstrate potential applications in pathology and developmental biology.

  8. Sensitivity assessment of wide Axial Field of View PET systems via Monte Carlo simulations of NEMA-like measurements

    International Nuclear Information System (INIS)

    The sensitivity characteristics of Positron Emission Tomography (PET) systems with wide Axial Field of View (AFOV) was studied by MonteCarlo simulations complemented by an approximate analytical model, aiming at full-body human PET systems with AFOV in the order of 200 cm. Simulations were based on the GEANT4 package and followed closely the NEMA NU-2 1994 norm. The sensitivity, dominated by the solid angle, grows strongly with the AFOV and with the axial acceptance angle, while the scatter fraction is almost independent from the geometry

  9. Práticas cirúrgicas baseadas em evidências: tomografia computadorizada helicoidal no diagnóstico da apendicite aguda Evidence-based surgical practices: helical computed tomography in acute appendicitis diagnosis

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Guimarães

    2008-08-01

    Full Text Available Os cirurgiões são instados a não somente ler os artigos dos periódicos, mas também a compreendê-los e analisá-los criticamente quanto à validade. Eles cuidam melhor dos seus pacientes se são capazes de analisar criticamente a literatura e aplicar os resultados a sua prática. Este é o segundo artigo de uma série - Práticas Cirúrgicas Baseadas em Evidência - que tem por objetivo apresentar a avaliação crítica de um teste diagnóstico.Surgeons are told that they need not only read journal articles, but also understand them and make a critical appraisal of their validity. They offer better care if they are able to appraise critically the original literature and apply the results to their practice. This is the second article of a series - Evidence-Based Surgical Practices - which focus on critical appraisal of a diagnostic test.

  10. Interleaved optical coherence tomography.

    Science.gov (United States)

    Lee, Hee Yoon; Sudkamp, Helge; Marvdashti, Tahereh; Ellerbee, Audrey K

    2013-11-01

    We present a novel and cost-effective technique--interleaved optical coherence tomography (iOCT)--to enhance the imaging speed of swept source OCT systems by acquiring data from multiple lateral positions simultaneously during a single wavelength sweep, using a single detector and a virtually imaged phase array (VIPA) as a multi-band demultiplexer. This technique uses spectral encoding to convert coherence length into higher imaging speed; the speed enhancement factor is independent of the source speed or center wavelength, and the effective A-scan rate scales linearly with sweep speed. The optical configuration requires only a change in the sample arm of a traditional OCT system and preserves the axial resolution and fall-off characteristic of a traditional SS-OCT using the same light source. Using 10 kHz, 20 kHz and 100 kHz sources we provide a first demonstration of image speed enhancement factors of up to 12, 6 and 10, respectively, which yield effective A-scan rates of 120 kHz, 120 kHz and 1 MHz for B-scan imaging, with a sensitivity of up to 82.5 dB. We also show that iOCT can image faster dynamics than traditional OCT B-scan imaging and is capable of 3D biological imaging. The iOCT concept suggests a new route to high-speed OCT imaging for laser developers: that is, by focusing on improving the coherence length and linewidth of existing and emerging sources. Hence, iOCT is a nice complement to ongoing research and commercial efforts to enable faster imaging through development of lasers with faster sweep rates, and offers new hope for existing sources with slow sweep rates and potential for enhancement of coherence length to compete with faster sources to achieve high-speed OCT. PMID:24216876

  11. Bioluminescence tomography with Gaussian prior

    OpenAIRE

    Gao, Hao; Zhao, Hongkai; Cong, Wenxiang; Wang, Ge

    2010-01-01

    Parameterizing the bioluminescent source globally in Gaussians provides several advantages over voxel representation in bioluminescence tomography. It is mathematically unique to recover Gaussians [Med. Phys. 31(8), 2289 (2004)] and practically sufficient to approximate various shapes by Gaussians in diffusive medium. The computational burden is significantly reduced since much fewer unknowns are required. Besides, there are physiological evidences that the source can be modeled by Gaussians....

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

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, F.

    1996-12-01

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

  13. Value of computed tomography for the diagnosis and pre and post-treatment work-up of aortic aneurysms. Comparison with angiographic findings. A report of data in 112 cases

    International Nuclear Information System (INIS)

    The authors report that CT scan provided decisive or complementary data, as compared to angiography, in 112 cases of aortic aneurysm. CT scan thus emerges as an useful tool. The inadequate angiographies were either nearly normal, or showed evidence that pointed to total arterial occlusion whose thrombotic and aneurysmal nature was demonstrated only upon computed tomography; CT scan proved irreplaceable for evaluating prostheses and postoperative complications. The axial transverse plane of CT sections explains why computed tomography is so informative: the channel, thrombosis, wall and peri-adventicia (fibrosis, fissuration) are visible successively from the center to the periphery. In the authors' opinion, the pretreatment evaluation of an aortic aneurysm should include a CT angioscan in addition to an angiography as the two procedures complement one another. After surgery, CT scan is even more widely indicated. CT scan is the primary procedure for controlling a prosthesis and often makes other investigations unnecessary

  14. Polarization converters based on axially symmetric twisted nematic liquid crystal.

    Science.gov (United States)

    Ko, Shih-Wei; Ting, Chi-Lun; Fuh, Andy Y-G; Lin, Tsung-Hsien

    2010-02-15

    An axially symmetric twisted nematic liquid crystal (ASTNLC) device, based on axially symmetric photoalignment, was demonstrated. Such an ASTNLC device can convert axial (azimuthal) to azimuthal (axial) polarization. The optical properties of the ASTNLC device are analyzed and found to agree with simulation results. The ASTNLC device with a specific device can be adopted as an arbitrary axial symmetric polarization converter or waveplate for axially, azimuthally or vertically polarized light. A design for converting linear polarized light to axially symmetric circular polarized light is also demonstrated. PMID:20389369

  15. Improving the lattice axial vector current

    CERN Document Server

    Horsley, R; Perlt, H; Rakow, P E L; Schierholz, G; Schiller, A; Zanotti, J M

    2015-01-01

    For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order $O(a)$ effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.

  16. Axial instability of rotating relativistic stars

    CERN Document Server

    Friedman, J L; Friedman, John L.; Morsink, Sharon M.

    1998-01-01

    Perturbations of rotating relativistic stars can be classified by their behavior under parity. For axial perturbations (r-modes), initial data with negative canonical energy is found with angular dependence $e^{im\\phi}$ for all values of $m\\geq 2$ and for arbitrarily slow rotation. This implies instability (or marginal stability) of such perturbations for rotating perfect fluids. This low $m$-instability is strikingly different from the instability to polar perturbations, which sets in first for large values of $m$. The timescale for the axial instability appears, for small angular velocity $\\Omega$, to be proportional to a high power of $\\Omega$. As in the case of polar modes, viscosity will again presumably enforce stability except for hot, rapidly rotating neutron stars. This work complements Andersson's numerical investigation of axial modes in slowly rotating stars.

  17. The axial distribution of reactivity coefficients

    International Nuclear Information System (INIS)

    The purpose of the present work is to investigate the correlation of the axial distributions of the different reactivity coefficients with the neutron flux and the neutron flux squared. Calculations were carried out for the Zion Unit 2 PWR. Reactivity coefficients, forward fluxes and adjoint fluxes were all computed and correlations obtained. The core length was divided into 7 axial regions in order to obtain the effect on reactivity in the reactor as a whole of changing the cross sections in each axial region in turn. The parameters chosen for change were coolant density, coolant temperature and fuel temperature. The results appear to bear out our original hypothesis that the reactivity coefficient profiles have a higher positive correlation with the total flux squared profile than with the linear flux profile. (authors). 5 refs., 2 figs

  18. Computed tomography studies of human brain movements

    International Nuclear Information System (INIS)

    Rhythmic brain movements have been revealed by sets of sequential computed tomography scans of human brains (seen retrospectively to be normal). These scans have shown that both (unenhanced) brain parenchymal density and the shapes of the elements of the supratentorial ventricular/cisternal system are subject to wave motions having similar periods - ranging from 26 s through 56 s, 77-96 s, 109 s and 224 s to 224 X 2 s (or even longer), with good correlation between peak values. These motions, as well as phase variations between the waves, suggest a peristaltic movement of cerebrospinal fluid through the ventricular/cisternal system with progressive axial damping

  19. Three-dimensional image reconstruction for PET by multi-slice rebinning and axial image filtering.

    Science.gov (United States)

    Lewittt, R M; Muehllehner, G; Karpt, J S

    1994-03-01

    A fast method is described for reconstructing volume images from three-dimensional (3D) coincidence data in positron emission tomography (PET). The reconstruction method makes use of all coincidence data acquired by high-sensitivity PET systems that do not have inter-slice absorbers (septa) to restrict the axial acceptance angle. The reconstruction method requires only a small amount of storage and computation, making it well suited for dynamic and whole-body studies. The method consists of three steps: (i) rebinning of coincidence data into a stack of 2D sinograms; (ii) slice-by-slice reconstruction of the sinogram associated with each slice to produce a preliminary 3D image having strong blurring in the axial (z) direction, but with different blurring at different z positions; and (iii) spatially variant filtering of the 3D image in the axial direction (i.e. 1D filtering in z for each x-y column) to produce the final image. The first step involves a new form of the rebinning operation in which multiple sinograms are incremented for each oblique coincidence line (multi-slice rebinning). The axial filtering step is formulated and implemented using the singular value decomposition (SVD). The method has been applied successfully to simulated data and to measured data for different kinds of phantom (multiple point sources, multiple discs, a cylinder with cold spheres, and a 3D brain phantom). PMID:15551583

  20. A pictorial review of atlanto-axial rotatory fixation: Key points for the radiologist

    International Nuclear Information System (INIS)

    Atlanto-axial rotatory fixation (AARF) is a rare condition which occurs more commonly in children than in adults. The terminology can be confusing and the condition is also known as 'atlanto-axial rotatory subluxation' and 'atlanto-axial rotary dislocation'. Rotatory fixation is the preferred term, however, as in most cases the fixation occurs within the normal range of rotation of the joint. By definition, therefore, the joint is neither subluxed nor dislocated. AARF is a cause of acquired torticollis. Diagnosis can be difficult and is often delayed. The radiologist plays a key role in confirming the diagnosis. The classification system proposed by Fielding in 1977 is most frequently used and will be discussed in detail. Given that this classification system was devised in the days before computed tomography (CT), as well as the fact that combined atlanto-axial and atlanto-occipital rotatory subluxation (AORF) is omitted from the classification, we propose a modification to the classification of this rare but significant disorder. The radiological findings in six cases of AARF will be illustrated, including a case with associated atlanto-occipital subluxation. The pertinent literature is reviewed and a more comprehensive classification system proposed. The imaging approach to diagnosis and the orthopaedic approach to management will be discussed. Roche, C.J. et al. (2001)

  1. A pictorial review of atlanto-axial rotatory fixation: Key points for the radiologist

    Energy Technology Data Exchange (ETDEWEB)

    Roche, Clare J.; O' Malley, Michael; Dorgan, John C.; Carty, Helen M

    2001-12-01

    Atlanto-axial rotatory fixation (AARF) is a rare condition which occurs more commonly in children than in adults. The terminology can be confusing and the condition is also known as 'atlanto-axial rotatory subluxation' and 'atlanto-axial rotary dislocation'. Rotatory fixation is the preferred term, however, as in most cases the fixation occurs within the normal range of rotation of the joint. By definition, therefore, the joint is neither subluxed nor dislocated. AARF is a cause of acquired torticollis. Diagnosis can be difficult and is often delayed. The radiologist plays a key role in confirming the diagnosis. The classification system proposed by Fielding in 1977 is most frequently used and will be discussed in detail. Given that this classification system was devised in the days before computed tomography (CT), as well as the fact that combined atlanto-axial and atlanto-occipital rotatory subluxation (AORF) is omitted from the classification, we propose a modification to the classification of this rare but significant disorder. The radiological findings in six cases of AARF will be illustrated, including a case with associated atlanto-occipital subluxation. The pertinent literature is reviewed and a more comprehensive classification system proposed. The imaging approach to diagnosis and the orthopaedic approach to management will be discussed. Roche, C.J. et al. (2001)

  2. Helical x-ray differential phase contrast computed tomography

    Science.gov (United States)

    Qi, Zhihua; Thériault-Lauzier, Pascal; Bevins, Nicholas; Zambelli, Joseph; Li, Ke; Chen, Guang-Hong

    2011-03-01

    Helical computed tomography revolutionized the field of x-ray computed tomography two decades ago. The simultaneous translation of an image object with a standard computed tomography acquisition allows for fast volumetric scan for long image objects. X-ray phase sensitive imaging methods have been studied over the past few decades to provide new contrast mechanisms for imaging an object. A Talbot-Lau grating interferometer based differential phase contrast imaging method has recently demonstrated its potential for implementation in clinical and industrial applications. In this work, the principles of helical computed tomography are extended to differential phase contrast imaging to produce volumetric reconstructions based on fan-beam data. The method demonstrates the potential for helical differential phase contrast CT to scan long objects with relatively small detector coverage in the axial direction.

  3. Cranial computerized tomography in children suffering from acute leukemia

    International Nuclear Information System (INIS)

    Cranial computerized (axial) tomography permits a more complete neurologic supervision of children with acute leukemia and a better knowledge of the frequency and varieties of cerebral complications in leukemia. Endocranial complications in acute leukemia are essentially infiltrative, hemorrhagic, infectious or iatrogenic. Cranial computerized tomography can demonstrate cerebral changes in meningeal leukemia, hemorrhages, calcifications, brain atrophy or leukencephalopathy. The preliminary results of cranial computerized tomography in childhood leukemia suggest that the iatrogenic main lesion of the brain due to combined radiation-chemotherapy is atrophy whereas that of the intrathecal cytostatic therapy is demyelination. Accurate diagnostics and control of possible cerebral complications in therapy of leukemia is essentially for appropriate therapeutic management. For that cranial computerized tomography is the best method to a effective supervision of the brain. (author)

  4. Selection rules and ratios for axial couplings

    CERN Document Server

    Buccella, F; Pugliese, A; Sorace, E

    1972-01-01

    The predictions for the axial couplings following from the use of the mixing operator U(Z), previously introduced to tilt the axial charges of SU/sub 6/ in the physical ones, are studied. The quantum number (-1)/sup L+L3/, where L and L/sub 3/ are the O/sub 3/ angular momentum and its third component, is shown to be conserved. From the properties of Z further predictions can be achieved as the D/F= /sup 3///sub 2/ for the /sup 1///sub 2//sup +/ baryon octet in general agreement with experiment. (14 refs).

  5. Axial Stiffness of Multiwalled Carbon Nanotubes

    OpenAIRE

    Zavalniuk, Vladimir

    2011-01-01

    The axial stiffness of MWCNTs is demonstrated to be determined only by several external shells (usually 3-5 and up to 15 for the extremely large nanotubes and high elongations) what is in a good agreement with experimentally observed inverse relation between the radius and Young modulus (i.e., stiffness) of MWCNTs. This result is a consequence of the van der Waals intershell interaction. The interpolating formula is obtained for the actual axial stiffness of MWCNT as a function of the tube ex...

  6. Axial Vircator for Electronic Warfare Applications

    Directory of Open Access Journals (Sweden)

    L. Drazan

    2009-12-01

    Full Text Available This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO, it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.

  7. Organ localization: Toward prospective patient-specific organ dosimetry in computed tomography

    International Nuclear Information System (INIS)

    Purpose: With increased focus on radiation dose from medical imaging, prospective radiation dose estimates are becoming increasingly desired. Using available populations of adult and pediatric patient phantoms, radiation dose calculations can be catalogued and prospectively applied to individual patients that best match certain anatomical characteristics. In doing so, the knowledge of organ size and location is a required element. Here, the authors develop a predictive model of organ locations and volumes based on an analysis of adult and pediatric computed tomography (CT) data. Methods: Fifty eight adult and 69 pediatric CT datasets were segmented and utilized in the study. The maximum and minimum points of the organs were recorded with respect to the axial distance from the tip of the sacrum. The axial width, midpoint, and volume of each organ were calculated. Linear correlations between these three organ parameters and patient age, BMI, weight, and height were determined. Results: No statistically significant correlations were found in adult patients between the axial width, midpoint, and volume of the organs versus the patient age or BMI. Slight, positive linear trends were found for organ midpoint versus patient weight (max r2 = 0.382, mean r2 = 0.236). Similar trends were found for organ midpoint versus height (max r2 = 0.439, mean r2 = 0.200) and for organ volume versus height (max r2 = 0.410, mean r2 = 0.153). Gaussian fits performed on probability density functions of the adult organs resulted in r2-values ranging from 0.96 to 0.996. The pediatric patients showed much stronger correlations overall. Strong correlations were observed between organ axial midpoint versus age, height, and weight (max r2 = 0.842, mean r2 = 0.790; max r2 = 0.949, mean r2 = 0.894; and max r2 = 0.870, mean r2 = 0.847, respectively). Moderate linear correlations were also observed for organ axial width versus height (max r2 = 0.772, mean r2 = 0.562) and for organ volume versus

  8. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Head What is CT Scanning of the ... Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a CT or CAT ...

  9. Absorbed and effective dose from spiral and computed tomography for the dental implant planning

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Beong Hee; Han, Won Jeong; Kim, Eun Kyung [Dankook Univ. School of Dentistry, Seoul (Korea, Republic of)

    2001-09-15

    To evaluate the absorbed and effective doses of spiral and computed tomography for the dental implant planning. For radiographic projection. TLD chips were placed in 22 sites of humanoid phantom to record the exposure to skin and the mean absorbed dose to bone marrow, thyroid, pituitary, parotid and submandibular glands and nesophages. Effective dose was calculated, using the method suggested by Frederiksen at al.. Patient situations of a single tooth gap in upper and lower midline region, edentulous maxilla and mandible were simulated for spiral tomography. 35 axial slices (maxilla) and 40 axial slices (mandible) with low and standard dose setting were used for computed tomography. All the radiographic procedures were repeated three times. The mean effective dose in case of maxilla was 0.865 mSv, 0.452 mSv, 0.136 mSv and 0.025 mSv, in spiral tomography of complete edentulous maxilla, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). That in case of mandible was 0.614 mSv, 0.448 mSv, 0.137 mSv and 0.036 mSv, in spiral tomography of complete edentulous mandible, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). Based on these results, it can be concluded that low mAs computed tomography is recommended instead of spiral tomography for the complete edentulous maxilla and mandible dental implant treatment planning.

  10. Absorbed and effective dose from spiral and computed tomography for the dental implant planning

    International Nuclear Information System (INIS)

    To evaluate the absorbed and effective doses of spiral and computed tomography for the dental implant planning. For radiographic projection. TLD chips were placed in 22 sites of humanoid phantom to record the exposure to skin and the mean absorbed dose to bone marrow, thyroid, pituitary, parotid and submandibular glands and nesophages. Effective dose was calculated, using the method suggested by Frederiksen at al.. Patient situations of a single tooth gap in upper and lower midline region, edentulous maxilla and mandible were simulated for spiral tomography. 35 axial slices (maxilla) and 40 axial slices (mandible) with low and standard dose setting were used for computed tomography. All the radiographic procedures were repeated three times. The mean effective dose in case of maxilla was 0.865 mSv, 0.452 mSv, 0.136 mSv and 0.025 mSv, in spiral tomography of complete edentulous maxilla, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). That in case of mandible was 0.614 mSv, 0.448 mSv, 0.137 mSv and 0.036 mSv, in spiral tomography of complete edentulous mandible, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). Based on these results, it can be concluded that low mAs computed tomography is recommended instead of spiral tomography for the complete edentulous maxilla and mandible dental implant treatment planning

  11. Knowledge Based Design of Axial Flow Compressor

    Directory of Open Access Journals (Sweden)

    Dinesh kumar.R

    2015-05-01

    Full Text Available In the aerospace industry with highly competitive market the time to design and delivery is shortening every day. Pressure on delivering robust product with cost economy is in demand in each development. Even though technology is older, it is new for each customer requirement and highly non-liner to fit one in another place. Gas turbine is considered one of a complex design in the aircraft system. It involves experts to be grouped with designers of various segments to arrive the best output. The time is crucial to achieve a best design and it needs knowledge automation incorporated with CAD/CAE tools. In the present work an innovative idea in the form of Knowledge Based Engineering for axial compressor is proposed, this includes the fundamental design of axial compressor integrated with artificial intelligence in the form of knowledge capturing and programmed with high level language (Visual Basis.Net and embedded into CATIA v5. This KBE frame work eases out the design and modeling of axial compressor design and produces 3D modeling for further flow simulation with fluid dynamic in Ansys-Fluent. Most of the aerospace components are developed through simulation driven product development and in this case it is established for axial compressor.

  12. The Axial Current in Electromagnetic Interaction

    CERN Document Server

    Cheoun, M K; Cheon, I T; Cheoun, Myung Ki; Cheon, Il-Tong

    1998-01-01

    We discussed the possibility that the charged axial currents of matter fields could be non-conserved in electromagnetic interaction at $O(e) $ order. It means that chiral symmetry is broken explicitly by electromagnetic interaction. This explicit symmetry breaking of chiral symmetry is shown to lead the mass differences between the charged and neutral particles of matter fields.

  13. Constant-axial-intensity nondiffracting beam.

    Science.gov (United States)

    Cox, A J; D'Anna, J

    1992-02-15

    Numerical solutions of the Fresnel diffraction integral with various apodizing filter functions are used to indicate that a so-called nondiffracting beam can be produced that maintains a constant spot size and constant axial intensity over a considerable range, approximately 30 m in our example. PMID:19784285

  14. Axially symmetric SU(3) gravitating skyrmions

    Energy Technology Data Exchange (ETDEWEB)

    Ioannidou, Theodora [Maths Division, School of Technology, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)]. E-mail: ti3@auth.gr; Kleihaus, Burkhard [Institut fuer Physik, Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany)]. E-mail: kleihaus@theorie.physik.uni-oldenburg.de; Zakrzewski, Wojtek [Department of Mathematical Sciences, University of Durham, Durham DH1 3LE (United Kingdom)]. E-mail: w.j.zakrzewski@durham.ac.uk

    2004-10-21

    Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [J. Math. Phys. 40 (1999) 6353]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail.

  15. Axially symmetric SU(3) Gravitating Skyrmions

    CERN Document Server

    Ioannidou, T A; Zakrzewski, W J; Ioannidou, Theodora; Kleihaus, Burkhard; Zakrzewski, Wojtek

    2004-01-01

    Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [1]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail.

  16. Axially symmetric SU(3) gravitating skyrmions

    International Nuclear Information System (INIS)

    Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [J. Math. Phys. 40 (1999) 6353]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail

  17. Primitive axial algebras of Jordan type

    OpenAIRE

    Hall, J I; Rehren, F; Shpectorov, S.

    2014-01-01

    An axial algebra over the field $\\mathbb F$ is a commutative algebra generated by idempotents whose adjoint action has multiplicity-free minimal polynomial. For semisimple associative algebras this leads to sums of copies of $\\mathbb F$. Here we consider the first nonassociative case, where adjoint minimal polynomials divide $(x-1)x(x-\\eta)$ for fixed $0\

  18. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Head Computed tomography (CT) of the head uses special x-ray ... What is CT Scanning of the Head? Computed tomography, more commonly known as a CT or CAT ...

  19. The spacetime outside a source of gravitational radiation: The axially symmetric null fluid

    CERN Document Server

    Herrera, L; Ospino, J

    2016-01-01

    We carry out a study of the exterior of an axially and reflection symmetric source of gravitational radiation. The exterior of such a source is filled with a null fluid produced by the dissipative processes inherent to the emission of gravitational radiation, thereby representing a generalization of the Vaidya metric for axially and reflection symmetric spacetimes. The role of the vorticity, and its relationship with the presence of gravitational radiation is put in evidence. The spherically symmetric case (Vaidya) is, asymptotically, recovered within the context of the $1+3$ formalism.

  20. Detection of hepatic tumor by means of single photon emission computed tomography, Gray scale ultrasonography, and computed tomography

    International Nuclear Information System (INIS)

    We have studied the hepatic tumor detection by single photon emission computed tomography (SPECT) using rotatory chair and gamma camera. SPECT were taken by multiple section slice not only in transaxial view, but also in frontal and sagital. The results were superior in detectability to conventional liver scintiphoto (CLS). In cases of obstructive jaundice, ultrasonography (US) and/or computed axial tomography (CAT) should be taken before SPECT, because there are various probabilities of evaluation like as false positive by means of SPECT. Simultaneous interpretation of SPECT, US, and CAT was more helpful than independent interpretation

  1. Role of Optical Coherence Tomography on Corneal Surface Laser Ablation

    OpenAIRE

    Ventura, Bruna V.; Moraes, Haroldo V.; Newton Kara-Junior; Santhiago, Marcony R.

    2012-01-01

    This paper focuses on reviewing the roles of optical coherence tomography (OCT) on corneal surface laser ablation procedures. OCT is an optical imaging modality that uses low-coherence interferometry to provide noninvasive cross-sectional imaging of tissue microstructure in vivo. There are two types of OCTs, each with transverse and axial spatial resolutions of a few micrometers: the time-domain and the fourier-domain OCTs. Both have been increasingly used by refractive surgeons and have spec...

  2. Optical Coherence Tomography of Retinal and Choroidal Tumors

    OpenAIRE

    Say, Emil Anthony T.; Shah, Sanket U.; Ferenczy, Sandor; Shields, Carol L.

    2011-01-01

    Optical coherence tomography (OCT) has revolutionized the field of ophthalmology since its introduction 20 years ago. Originally intended primarily for retina specialists to image the macula, it has found its role in other subspecialties that include glaucoma, cornea, and ocular oncology. In ocular oncology, OCT provides axial resolution to approximately 7 microns with cross-sectional images of the retina, delivering valuable information on the effects of intraocular tumors on the retinal arc...

  3. Estudo de caso de oferta induzindo a demanda: o caso da oferta de exames de imagem (tomografia axial computadorizada e ressonância magnética na Unimed-Manaus Case study of supply induced demand: the case of provision of imaging scans (computed tomography and magnetic resonance at Unimed-Manaus

    Directory of Open Access Journals (Sweden)

    Edson de Oliveira Andrade

    2011-04-01

    Full Text Available OBJETIVO: Apresentar a experiência de uma operadora de plano de saúde (Unimed-Manaus na cidade de Manaus, Estado do Amazonas, com o credenciamento de serviços de imagem e a indução de demanda pela oferta dos novos serviços (Lei de Roemer. MÉTODOS: Trata-se de uma pesquisa de caráter retrospectivo, com estudo de série temporal, abordando o período de janeiro de 1998 a junho de 2004, lapso de tempo em que ocorreu a implantação dos serviços de tomografia computadorizada e da ressonância magnética no âmbito dos serviços oferecidos por aquele plano de saúde. A análise estatística consistiu em uma parte descritiva e uma inferencial, sendo esta última utilizando teste paramétrico de média (teste t de Student e ANOVA e o teste de correlação de Pearson. Foi adotado um alfa de 5% e um intervalo de confiança de 95%. RESULTADOS: Foi possível identificar na Unimed-Manaus que a oferta de novos serviços de imagem foi capaz de, por si só, gerar um aumento da demanda do serviço caracterizando o fenômeno descrito por Roemer. CONCLUSÃO: Os resultados deste trabalho ressaltam a necessidade de se estar atento ao fato de que a oferta de novos serviços no setor da saúde poderá acarretar, por si só, um aumento de sua utilização sem que haja uma demanda real.OBJECTIVE: To present the experience of a health plan operator (Unimed-Manaus in Manaus, Amazonas, Brazil, with the accreditation of imaging services and the demand induced by the supply of new services (Roemer's Law. METHODS: This is a retrospective work studying a time series covering the period from January 1998 to June 2004, in which the computed tomography and the magnetic resonance imaging services were implemented as part of the services offered by that health plan operator. Statistical analysis consisted of a descriptive and an inferential part, with the latter using a mean parametric test (Student T-test and ANOVA and the Pearson correlation test. A 5% alpha and a 95

  4. High-speed frequency-domain terahertz coherence tomography.

    Science.gov (United States)

    Yahng, Ji Sang; Park, Choon-Su; Don Lee, Hwi; Kim, Chang-Seok; Yee, Dae-Su

    2016-01-25

    High-speed frequency-domain terahertz (THz) coherence tomography is demonstrated using frequency sweeping of continuous-wave THz radiation and beam steering. For axial scanning, THz frequency sweeping with a kHz sweep rate and a THz sweep range is executed using THz photomixing with an optical beat source consisting of a wavelength-swept laser and a distributed feedback laser diode. During the frequency sweep, frequency-domain THz interferograms are measured using coherent homodyne detection employing signal averaging for noise reduction and used as axial-scan data via fast Fourier transform. Axial-scan data are acquired while scanning a transverse range of 100 × 100 mm2 by use of a THz beam scanner with moving neither sample nor THz transmitter/receiver unit. It takes 100 s to acquire axial-scan data for 100 × 100 points with 5 averaged traces at a sweep rate of 1 kHz. THz tomographic images of a glass fiber reinforced polymer sample with artificial internal defects are presented, acquired using the tomography system. PMID:26832489

  5. Axial flow positive displacement worm compressor

    Science.gov (United States)

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

    2010-01-01

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

  6. Microwave axial dielectric properties of carbon fiber

    Science.gov (United States)

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

    2015-10-01

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

  7. Direct optical nanoscopy with axially localized detection

    CERN Document Server

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

    2014-01-01

    Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Herein we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called Supercritical Angle Fluorescence (SAF) can be captured using a hig-NA objective and used to determine the axial position of the fluorophore with nanometer precision. We introduce a new technique for 3D nanoscopy that combines direct STochastic Optical Reconstruction Microscopy (dSTORM) imaging with dedicated detection of SAF emission. We demonstrate that our approach of a Direct Optical Nanoscopy with Axially Localized Detection (DONALD) yields a typical isotropic 3D localization precision of 20 nm.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-03-01

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

  10. On the problem of axial anomaly in supersymmetric gauge theories

    International Nuclear Information System (INIS)

    The explicit relation is found between the axial current obeying the Adler-Bardeen theorem and the supersymmetric one belonging to a supermultiplet. It is shown that the axial and superconformal anomalies are consistent in all orders of perturbation theory

  11. Multimode interaction in axially excited cylindrical shells

    OpenAIRE

    Silva F. M. A.; Rodrigues L.; Gonçalves P. B.; Del Prado Z. J. G. N

    2014-01-01

    Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural fr...

  12. Axial flux permanent magnet brushless machines

    CERN Document Server

    Gieras, Jacek F; Kamper, Maarten J

    2008-01-01

    Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators

  13. Axial Flow Characteristics within a Screw Compressor

    OpenAIRE

    Nouri, J. M.; Guerrato, D.; Stosic, N.; Arcoumanis, C.

    2008-01-01

    Angle-resolved axial mean flow and turbulence characteristics were measured inside the working chamber of the male rotor of a screw compressor with high spatial and temporal resolution using laser Doppler velocimetry at two rotor speeds, 750 and 1000 rpm. Measurements were performed through a transparent window near the discharge port to allow the application of various laser techniques. The results showed that an angular resolution up to 2° could fully describe the flow variation inside the ...

  14. Axial force measurement for esophageal function testing

    OpenAIRE

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

    2009-01-01

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the “golden standard” for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure o...

  15. Axially evoked postural reflexes: influence of task

    OpenAIRE

    Govender, Sendhil; Dennis, Danielle L.; Colebatch, James G.

    2014-01-01

    Postural reflexes were recorded in healthy subjects (n = 17) using brief axial accelerations and tap stimuli applied at the vertebra prominens (C7) and manubrium sterni. Short latency (SL) responses were recorded from the soleus, hamstrings and tibialis anterior muscles and expressed as a percentage of the background EMG prior to stimulus onset. In the majority of postural conditions tested, subjects were recorded standing erect and leaning forward with their feet together. The SL response wa...

  16. Numerical simulation of an axial blood pump.

    Science.gov (United States)

    Chua, Leok Poh; Su, Boyang; Lim, Tau Meng; Zhou, Tongming

    2007-07-01

    The axial blood pump with a magnetically suspended impeller is superior to other artificial blood pumps because of its small size. In this article, the distributions of velocity, path line, pressure, and shear stress in the straightener, the rotor, and the diffuser of the axial blood pump, as well as the gap zone were obtained using the commercial software, Fluent (version 6.2). The main focus was on the flow field of the blood pump. The numerical results showed that the axial blood pump could produce 5.14 L/min of blood at 100 mm Hg through the outlet when rotating at 11,000 rpm. However, there was a leakage flow of 1.06 L/min in the gap between the rotor cylinder and the pump housing, and thus the overall flow rate the impeller could generate was 6.2 L/min. The numerical results showed that 75% of the scalar shear stresses (SSs) were less than 250 Pa, and 10% were higher than 500 Pa within the whole pump. The high SS region appeared around the blade tip where a large variation of velocity direction and magnitude was found, which might be due to the steep angle variation at the blade tip. Because the exposure time of the blood cell at the high SS region within the pump was relatively short, it might not cause serious damage to the blood cells, but the improvement of blade profile should be considered in the future design of the axial pump. PMID:17584481

  17. DYNAMIC RESPONSES OF VISCOELASTIC AXIALLY MOVING BELT

    Institute of Scientific and Technical Information of China (English)

    李映辉; 高庆; 蹇开林; 殷学纲

    2003-01-01

    Based on the Kelvin viscoelastic differential constitutive law and the motion equation of the axially moving belt, the nonlinear dynamic model of the viscoelastic axial moving belt was established. And then it was reduced to be a linear differential system which the analytical solutions with a constant transport velocity and with a harmonically varying transport velocity were obtained by applying Lie group transformations. According to the nonlinear dynamic model, the effects of material parameters and the steady-state velocity and the perturbed axial velocity of the belt on the dynamic responses of the belts were investigated by the research of digital simulation. The result shows: 1 ) The nonlinear vibration frequency of the belt will become small when the relocity of the belt increases. 2 ) Increasing the value of viscosity or decreasing the value of elasticity leads to a deceasing in vibration frequencies. 3 ) The most effects of the transverse amplitudes come from the frequency of the perturbed velocity when the belt moves with harmonic velocity.

  18. The window of opportunity: a relevant concept for axial spondyloarthritis

    OpenAIRE

    Robinson, Philip C.; Brown, Matthew A.

    2014-01-01

    The window of opportunity is a concept critical to rheumatoid arthritis treatment. Early treatment changes the outcome of rheumatoid arthritis treatment, in that response rates are higher with earlier disease-modifying anti-rheumatic drug treatment and damage is substantially reduced. Axial spondyloarthritis is an inflammatory axial disease encompassing both nonradiographic axial spondyloarthritis and established ankylosing spondylitis. In axial spondyloarthritis, studies of magnetic resonanc...

  19. Extra-Axial Medulloblastoma in the Cerebellar Hemisphere

    OpenAIRE

    Chung, Eui Jin; Jeun, Sin Soo

    2014-01-01

    Extra-axial medulloblastoma is a rare phenomenon. We report a case in a 5-year-old boy who presented with nausea, vomiting, and gait disturbance. He was treated with total removal of the tumor. This is the first case of an extra-axially located medulloblastoma occurring in the cerebellar hemisphere posteriolateral to the cerebellopontine angle in Korea. Although the extra-axial occurrence of medulloblastoma is rare, it should be considered in the differential diagnosis of extra-axial lesions ...

  20. Turbocharging Quantum Tomography.

    Energy Technology Data Exchange (ETDEWEB)

    Blume-Kohout, Robin J; Gamble, John King,; Nielsen, Erik; Maunz, Peter Lukas Wilhelm; Scholten, Travis L.; Rudinger, Kenneth Michael

    2015-01-01

    Quantum tomography is used to characterize quantum operations implemented in quantum information processing (QIP) hardware. Traditionally, state tomography has been used to characterize the quantum state prepared in an initialization procedure, while quantum process tomography is used to characterize dynamical operations on a QIP system. As such, tomography is critical to the development of QIP hardware (since it is necessary both for debugging and validating as-built devices, and its results are used to influence the next generation of devices). But tomography su %7C ers from several critical drawbacks. In this report, we present new research that resolves several of these flaws. We describe a new form of tomography called gate set tomography (GST), which unifies state and process tomography, avoids prior methods critical reliance on precalibrated operations that are not generally available, and can achieve unprecedented accuracies. We report on theory and experimental development of adaptive tomography protocols that achieve far higher fidelity in state reconstruction than non-adaptive methods. Finally, we present a new theoretical and experimental analysis of process tomography on multispin systems, and demonstrate how to more e %7C ectively detect and characterize quantum noise using carefully tailored ensembles of input states.

  1. Unusual case of infantile fibrosarcoma evaluated on F-18 fluorodeoxyglucose positron emission tomography-computed tomography.

    Science.gov (United States)

    Bedmutha, Akshay; Singh, Natasha; Shivdasani, Divya; Gupta, Nitin

    2016-01-01

    Infantile fibrosarcoma (IFS) is a rare soft-tissue sarcoma originating from extremities and occasionally from axial soft tissue. The prognosis is good with favorable long-term survival. It is rarely metastasizing tumor, the chances being lesser with IFS originating from extremities. Use of neoadjuvant chemotherapy (NACT) as a treatment regime further reduces the chances of local relapse and distant metastasis. The organs commonly affected in metastatic IFS are lungs and lymph nodes. We report an unusual case of an IFS originating from extremity, which received NACT, yet presented with an early metastatic disease involving soft tissues and sparing lungs and lymph nodes, as demonstrated on fluorodeoxyglucose positron emission tomography-computed tomography. PMID:27385891

  2. Resolution of axial anomaly problem in supersymmetric gauge theories

    International Nuclear Information System (INIS)

    The explicit form of transformation is found which converters the operators, involved in axial anomaly, from the renormalization scheme obeying the Adler-BaAdeen theorem to a supersymmetric one. It is shown that there is no contradiction between axial current and superconformal anomalies. In supersymmetric scheme the axial current and its anomaly belong to the corresponding supermultiplets

  3. A new strategy of axial power distribution control based on three axial offsets concept

    International Nuclear Information System (INIS)

    We have proposed a very simple control procedure for axial xenon oscillation control based on a characteristic trajectory. The trajectory is drawn by three offsets of power distributions, namely, AOp, AOi and AOx. They are defined as the offset of axial power distribution, the offset of the power distribution under which the current iodine distribution is obtained as the equilibrium and that for xenon distribution, respectively. When these offsets are plotted on X-Y plane for (AOp-AOx, AOi-AOx) the trajectory draws a quite characteristic ellipse (or an elliptic spiral). On the other hands, Constant Axial Offset Control (CAOC) procedure is adopted as axial power distribution control strategy during both base load and load following operations in domestic PWRs. In the previous paper, we have presented an innovative procedure of axial power distribution control during load following in PWRs based on this trajectory such that the AOp-AOx is to be controlled to zero when the value deviates the pre-determined limiting values. In this paper we propose a modified control strategy to get more stability of axial power distributions. In this strategy, we control the trajectory to be close to the major axis of the ellipse when the power distribution reaches the limiting values. In other words, the plot is not controlled only to reduce AOp-AOx but also AOi-AOx is taken into account at the same time. It is known that when the plot is controlled to the major axis, it means that the point gives the peak position of axial xenon oscillation. Therefore xenon oscillation will not increase its amplitude any more. Thus more stable axial power distribution control is attained. This kind of design concept is quite important especially for the future PWRs with elongated fuel length and longer core life. Because in a longer effective core and also the longer core life, it has been known that the stability of axial xenon oscillation becomes more unstable. In this paper, some simulation

  4. Computed tomography of stress fracture

    International Nuclear Information System (INIS)

    An athletic young female developed gradual onset of pain in the right leg. Plain radiographs demonstrated solid periosteal reaction in the tibia compatible with stress fracture. She stopped sport activites but her pain continued. Follow-up radiographs of the tibia revealed changes suspicious for osteoid osteoma. Computed tomography (CT) scan demonstrated periosteal reaction, but in addition, lucent fracture lines in the tibial cortex were evident. CT obviated the need for more invasive diagnostic procedures in this patient. In selected cases CT may be useful to confirm the diagnosis of stress fracture when plain radiographic or routine tomographic studies are not diagnostic. (orig.)

  5. Soft X-ray Tomography and Cryogenic Light Microscopy: The Cool Combination in Cellular Imaging

    OpenAIRE

    McDermott, Gerry; Le Gros, Mark A.; Knoechel, Christian G.; Uchida, Maho; Larabell, Carolyn A.

    2009-01-01

    Soft x-ray tomography (SXT) is ideally suited to imaging sub-cellular architecture and organization, particularly in eukaryotic cells. SXT is similar in concept to the well-established medical diagnostic technique computed axial tomography (CAT), except SXT is capable of imaging with a spatial resolution of 50 nm, or better. In soft x-ray tomography (SXT) cells are imaged using photons from a region of the spectrum known as the ‘water window’. This results in quantitative, high-contrast image...

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

    Science.gov (United States)

    Koplow, Jeffrey P.

    2016-02-16

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

  7. Abnormal access of axial vibrotactile input to deafferented somatosensory cortex in human upper limb amputees.

    Science.gov (United States)

    Kew, J J; Halligan, P W; Marshall, J C; Passingham, R E; Rothwell, J C; Ridding, M C; Marsden, C D; Brooks, D J

    1997-05-01

    input delivered to the axial body surface may gain access to the S1 hand/arm area in some humans who have suffered extensive deafferentation of this area. The findings are consistent with the hypothesis that deafferentation of an area of S1 may result in activation of previously dormant inputs from body surfaces represented in immediately adjacent parts of S1. The results also provide evidence that changes in functional connectivity between these adjacent areas of the cortex play a role in the somatotopic reorganization. PMID:9163390

  8. CFD Simulation of Casing Treatment of Axial Flow Compressors

    Science.gov (United States)

    DeWitt, Kenneth

    2005-01-01

    A computational study is carried out to understand the physical mechanism responsible for the improvement in stall margin of an axial flow rotor due to the circumferential casing grooves. It is shown that the computational tool used predicts an increase in operating range of the rotor when casing grooves are present. A budget of the axial momentum equation is carried out at the rotor casing in the tip gap in order to uncover the physical process behind this stall margin improvement. It is shown that for the smooth casing the net axial pressure force . However in the presence of casing grooves the net axial shear stress force acting at the casing is augmented by the axial force due to the radial transport of axial momentum, which occurs across the grooves and power stream interface. This additional force adds to the net axial viscous sheer force and thus leads to an increase in the stall margin of the rotor.

  9. Computed tomography of traumatic intracranial lesions

    International Nuclear Information System (INIS)

    The cranial computed tomography (CT) is a new radiological technique with which, for the first time, minimal differences an attenuation by intracranial soft tissue can be measured exactly. The basic physical principles of computed tomography have been extensively presented by Hounsfield (1973). It is well established that the attenuation of extravasated blood measures between 35 and 45 Hounsfield units. Therefore no difficulty should be encountered in the recognition and diagnosis of extra-axial hematoma and cerebral contusion since the density of the brain parenchyma never measures more than 25 units. As the constant increase in high velocity accidents and violence, the problem of acute head injury is one of the matters of great importance in today's medical practice. Therefore it is very important to figure out the method that would allow us to diagnose easily and precisely the effects of trauma upon the brain in order to institute the proper treatment at the earliest possible moment. Computed tomography allows us to make a diagnosis quickly and in a non-invasive manner. The CT scan was carried out on 310 head trauma cases in the department of radiology, St. Mary's and Kang Nam St. Mary's Hospital, Catholic Medical College, for 16 months from June 1979 to October 1980. All the scans were obtained with the Hitachi CT-H2 scanner and the scans were repeated following intravenous injection of high dose of contrast media (roughly 1.8 cc per kg body weight of 60% Conray). We have reviewed the CT scans of 310 patients got acute head injury in order to assess the location of brain lesions, the relationship between the CT densities of hematomas and their stage, the shape and mass effect of the extra-axial hematomas, and the effect of contrast enhancement. The results were as follows: 1. Of all 310 cases of the head injuries, epidural hematoma was 13.5%, subdural hematoma was 8.7%, subdural hygroma was 10%, cerebral contusion was 39%, hydrocephalus and atrophy was 3.9% and

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

    Science.gov (United States)

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

    2015-11-01

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

  11. Axial electron-channelling analysis of perovskite

    International Nuclear Information System (INIS)

    The orientation dependence of characteristic X-ray emission (the Borrmann effect) under near-zone-axis diffraction conditions has been used to identify the site preferences of strontium, zirconium and uranium impurities within a CaTiO3 (perovskite) host structure. As characteristic emission lines from these impurities occur at both higher and lower energies than the calcium or titanium K-shell excitations, effects of delocalization are clearly measureable, and are used as a tool in axial electron channeling or ALCHEMI analysis. It is found that strontium and uranium strongly partition into calcium sites, whereas zirconium occupies titanium sites. (author)

  12. Single Band Helical Antenna in Axial Mode

    Directory of Open Access Journals (Sweden)

    Parminder Singh

    2012-11-01

    Full Text Available Helical antennas have been widely used in a various useful applications, due to their low weight and low profile conformability, easy and cheap realization.Radiation properties of this antenna are examined both theoretically and experimentally. In this paper, an attempt has been made to investigate new helical antenna structure for Applications. CST MWS Software is used for the simulation and design calculations of the helical antennas. The axial ratio, return loss, VSWR, Directivity, gain, radiation pattern is evaluated. Using CST MWS simulation software proposed antenna is designed/simulated and optimized. The antenna exhibits a single band from 0 GHz to 3 GHz for GPS and several satellite applications

  13. Resonances in axially symmetric dielectric objects

    CERN Document Server

    Helsing, Johan

    2016-01-01

    A high-order convergent and robust numerical solver is constructed and used to find complex eigenwavenumbers and electromagnetic eigenfields of dielectric objects with axial symmetry. The solver is based on Fourier--Nystr\\"om discretization of M\\"uller's combined integral equations for the transmission problem and can be applied to demanding resonance problems at microwave, terahertz, and optical wavelengths. High achievable accuracy, even at very high wavenumbers, makes the solver ideal for benchmarking and for assessing the performance of general purpose commercial software.

  14. Cervical Spine Axial Rotation Goniometer Design

    Directory of Open Access Journals (Sweden)

    Emin Ulaş Erdem

    2012-06-01

    Full Text Available To evaluate the cervical spine rotation movement is quiet harder than other joints. Configuration and arrangement of current goniometers and devices is not always practic in clinics and some methods are quiet expensive. The cervical axial rotation goniometer designed by the authors is consists of five pieces (head apparatus, chair, goniometric platform, eye pads and camera. With this goniometer design a detailed evaluation of cervical spine range of motion can be obtained. Besides, measurement of "joint position sense" which is recently has rising interest in researches can be made practically with this goniometer.

  15. Thermophoretic motion of bodies with axial symmetry

    International Nuclear Information System (INIS)

    Thermophoresis of axially symmetric bodies is investigated to first order in the Knudsen number, K n. The study is made in the limit where the typical length of the immersed body is small compared with the mean free path. It is shown that in this case, in contrast to what is the case for spherical bodies, the arising thermal force on the body is not in general anti-parallel to the temperature gradient. It is also shown that the gas exerts a torque on the body, which in magnitude and direction depends on the body geometry. Equations of motion describing the body movement are derived. Stationary solutions are studied

  16. Children's (Pediatric) CT (Computed Tomography)

    Science.gov (United States)

    ... Site Index A-Z Children's (Pediatric) CT (Computed Tomography) Pediatric computed tomography (CT) is a fast, painless exam that uses ... of Children's CT? What is Children's CT? Computed tomography, more commonly known as a CT or CAT ...

  17. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Sinuses What is CT (Computed Tomography) of the Sinuses? What are ...

  18. Computerized tomography: Techniques

    International Nuclear Information System (INIS)

    The book is an introduction to the physical and technical fundamentals of computerized tomography. The measuring and imaging mechanisms of the various CT techniques are described with a view to relevant medical perspectives and potential side effects. Particular regard is given to magnetic resonance tomography. (orig./MG)

  19. Tomography of nonclassical states

    NARCIS (Netherlands)

    Bazrafkan, MR; Man'ko, [No Value

    2003-01-01

    A review of the symplectic tomography method is presented. Superpositions of different types of photon states are considered within the framework of the tomography approach. Such nonclassical photon states as even and odd coherent states, crystallized Schrodinger cat states, and other superposition

  20. Axial vessel widening in arborescent monocots.

    Science.gov (United States)

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

    2014-02-01

    Dicotyledons have evolved a strategy to compensate for the increase in hydraulic resistance to water transport with height growth by widening xylem conduits downwards. In monocots, the accumulation of hydraulic resistance with height should be similar, but the absence of secondary growth represents a strong limitation for the maintenance of xylem hydraulic efficiency during ontogeny. The hydraulic architecture of monocots has been studied but it is unclear how monocots arrange their axial vascular structure during ontogeny to compensate for increases in height. We measured the vessel lumina and estimated the hydraulic diameter (Dh) at different heights along the stem of two arborescent monocots, Bactris gasipaes (Kunth) and Guadua angustifolia (Kunth). For the former, we also estimated the variation in Dh along the leaf rachis. Hydraulic diameter increased basally from the stem apex to the base with a scaling exponent (b) in the range of those reported for dicot trees (b = 0.22 in B. gasipaes; b = 0.31 and 0.23 in G. angustifolia). In B. gasipaes, vessels decrease in Dh from the stem's centre towards the periphery, an opposite pattern compared with dicot trees. Along the leaf rachis, a pattern of increasing Dh basally was also found (b = 0.13). The hydraulic design of the monocots studied revealed an axial pattern of xylem conduits similar to those evolved by dicots to compensate and minimize the negative effect of root-to-leaf length on hydrodynamic resistance to water flow. PMID:24488857

  1. The failure of axially loaded steel columns

    International Nuclear Information System (INIS)

    Slender compression steel members fail by elastic bucking, and short compression members may be loaded until the steel yields. In the majority of usual situations, failure occurs by inelastic buckling after a portion of the cross section has yielded. Residual stresses are the primary cause of the nonlinear protion of the average stress strain curve of axially loaded compression members (huber and Beedle, 1954). A number of theories tackled the problem of inelastic bucking. The LRFD Code ended with adopting an empirical parabolic equation that is stitched to the Euler hyperbola at the column slenderness value of λ C =2 square root and is believed to provide a reasonable approximation for column strength curves. The analysis of steel sections used in this paper defines an explicit from of failure to define the failure load of axially loaded columns in the inelastic range. inelastic bucking is defined in terms of the elaSTIC bucking of transformed sections. Two examples are used to clarify the method of analysis that accounts for residual stresses. (author). 9 refs., 5 figs

  2. Atroposelective Synthesis of Axially Chiral Thiohydantoin Derivatives.

    Science.gov (United States)

    Sarigul, Sevgi; Dogan, Ilknur

    2016-07-15

    Nonracemic axially chiral thiohydantoins were synthesized atroposelectively by the reaction of o-aryl isothiocyanates with amino acid ester salts in the presence of triethylamine (TEA). The synthesis of the nonaxially chiral derivatives, however, gave thiohydantoins racemized at C-5 of the heterocyclic ring. The micropreparatively resolved enantiomers of the nonaxially chiral derivatives from the racemic products were found to be optically stable under neutral conditions. On formation of the 5-methyl-3-arylthiohydantoin ring, bulky o-aryl substituents at N3 were found to suppress the C-5 racemization and in this way enabled the transfer of chirality from the α-amino acid to the products. The corresponding 5-isopropylthiohydantoins turned out to be more prone to racemization at C-5 during the ring formation. The isomer compositions of the synthesized axially chiral thiohydantoins have been determined through HPLC analyses with chiral stationary phases. In most cases a high prevalence of the P isomers over the M isomers has been obtained. The barriers to rotation determined around the Nsp(2)-Caryl chiral axis were found to be dependent upon the size of the o-halo aryl substituents. PMID:27322739

  3. Proton spin and baryon octet axial couplings

    International Nuclear Information System (INIS)

    Peripheral spin structure of the nucelon generated by the soft mesonic radiative corrections is studied within the light-cone perturbation theory. Starting with the tree-level SU(6) symmetry, we find a good description of the axial-vector couplings in β-decay of hyperons. We study the proton helicity flow from the baryonic core to the angular momentum of the pionic cloud. It is found that in the relativistic light-cone approach the spin-flip pattern is different from that in the coventional non-relativistic models. The axial-vector current matrix elements are shown to receive large corrections from beyond the conventional static limit. The important virtue of using the light-cone vertex functions of the meson-baryon Fock components of the proton is that the local gauge invariance and the energy-momentum sum rule are satisfied automatically. We infer the radius of the light-cone form factor from an analysis of the experimental data on the fragmentation of high-energy protons into nucleons and hyperons-the process dominated by stripping off the mesons of the meson-baryon Fock states. (orig.)

  4. Estimation of Reversed Flow in Long Pipeline Based on Axial Vibration Model of Dense Paste

    Directory of Open Access Journals (Sweden)

    Fuyan Lyu

    2016-01-01

    Full Text Available Intense axial vibration of the paste and the reversed flow make damage to the transportation system and lag the transport progress. This paper analyzed the axial vibration of the paste by building the vibration model according to the working situations of the system. The amount of the reversed flow share is then estimated based on the formed axial vibration model. The estimation of the reversed flow is carried out by counting the amount of the decompressed paste in certain time, which is being relative to the displacement in a single process of the vibration in numerical. The estimation of the reversed flow share of coal slime paste under certain transportation conditions was given and compared with the result based on the wave velocity method. It is evident that the introduction of axial vibration model into the study of the pipeline transportation system is feasible and reasonable, which also supplements the theoretical foundation for the analysis of dense paste vibrations in pipeline transportation system and its impacts on the system.

  5. Presumed orbital sarcoidosis: report of a case followed by computerized axial tomography and conjunctival biopsy.

    Science.gov (United States)

    Nichols, C W; Mishkin, M; Yanoff, M

    1978-01-01

    A thirty-two-year old woman with known sarcoidosis was seen in the Ophthalmology Clinic because of discomfort in the left eye and orbit when looking up. A CT scan showed a small mass in the posterior left orbit. Conjunctival biopsy of the left eye showed a granuloma consistent with sarcoid. Rapid resolution of her condition occurred with prednisone therapy. One year later she had a recurrence with inability to elevate or depress the left eye. Similar, but more extensive, changes were seen on a CT scan. Conjunctival biopsy again was positive. With steroid therapy rapid and complete resolution occurred both clinically and as demonstrated by a CT scan. The relationship between her orbital mass and systemic sarcoidosis is discussed. Images FIGURE 1 A FIGURE 1 B FIGURE 1 C FIGURE 1 D FIGURE 2 A FIGURE 2 B FIGURE 2 C FIGURE 2 D FIGURE 3 A FIGURE 3 B FIGURE 3 C FIGURE 3 D FIGURE 4 A FIGURE 4 B FIGURE 4 C FIGURE 4 D FIGURE 5 A FIGURE 5 B FIGURE 5 C FIGURE 5 D PMID:754385

  6. The place of computerized axial tomography in the evaluation of acetabular fractures

    OpenAIRE

    Asik, Mehmet; Akman, Senol; Taser, Omer; Aritamur, Ayhan

    2004-01-01

    Besides the importance of standard AP and Judet s 45° iliac and obturator pelvic views, CAT has proved to be very useful in the evaluation of the fractures of the acetabulum. Of 96 patients with acetabular fractures, who applied to the Orthopaedics and Traumatology Department, Istanbul Medical Faculty, Istanbul University between 1987 and 1991 in addition to conventional radiography, CAT investigation was done in 32 patients for whom it was considered necessary. The results of both convention...

  7. The clinical significance of computerized axial tomography (CAT) in consideration of conventional diagnostic methods

    International Nuclear Information System (INIS)

    Regarding CAT of the intracranial region, the article informs on a) techniques of examination including the production of normal structures, b) the recognizable pathological changes, c) possibilities of enhancement, d) possibilities of course observation, e) limitations of the methods, as well as on f) risk/benefit aspects g) benefit/cost calculations as compared to conventional methods, and on h) the influence of CAT on the frequency of conventional methods of examination. Regarding CAT of the extracranial region, the information available up to the meeting is reported on. (orig./LH)

  8. Axial stress corrosion cracking forming method to metal tube

    International Nuclear Information System (INIS)

    Generally, it is more difficult in a metal tube, to intentionally cause a stress corrosion cracking in axial direction than in circumferential direction. In the present invention, a bevel is formed on a metal tube and welding is conducted in circumferential direction along the bevel, and welding is conducted in axial direction partially to the portion welded in circumferential direction. Namely, a bevel is formed in circumferential direction to an abutting portion of thick-walled metal tubes with each other, welding is conducted in circumferential direction along the bevel, and welding is conducted in axial direction partially to a portion welded in circumferential direction. With such procedures, since tensile stress in the circumferential direction is increased partially at a portion welded in axial direction, stress corrosion cracking is caused in axial direction at the portion. Then, stress corrosion cracking in axial direction can thus be formed on the thick-walled metal tube. (N.H.)

  9. Universal Axial Algebras and a Theorem of Sakuma

    OpenAIRE

    Hall, J I; Rehren, F; Shpectorov, S.

    2013-01-01

    In the first half of this paper, we define axial algebras: nonassociative commutative algebras generated by axes, that is, semisimple idempotents---the prototypical example of which is Griess' algebra [C85] for the Monster group. When multiplication of eigenspaces of axes is controlled by fusion rules, the structure of the axial algebra is determined to a large degree. We give a construction of the universal Frobenius axial algebra on $n$ generators with a specified fusion rules, of which all...

  10. Composite Axial Flow Propulsor for Small Aircraft

    Directory of Open Access Journals (Sweden)

    R. Poul

    2005-01-01

    Full Text Available This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element  Method. The skin of the blade is calculated as a laminate and the foam core as a solid. A static and dynamic analysis were made. The RTM technology is compared with other technologies and is described in detail. 

  11. Axially symmetric static sources of gravitational field

    CERN Document Server

    Hernandez-Pastora, J L; Martin, J

    2016-01-01

    A general procedure to find static and axially symmetric, interior solutions to the Einstein equations is presented. All the so obtained solutions, verify the energy conditions for a wide range of values of the parameters, and match smoothly to some exterior solution of the Weyl family, thereby representing globally regular models describing non spherical sources of gravitational field. In the spherically symmetric limit, all our models converge to the well known incompressible perfect fluid solution.The key stone of our approach is based on an ansatz allowing to define the interior metric in terms of the exterior metric functions evaluated at the boundary source. Some particular sources are obtained, and the physical variables of the energy-momentum tensor are calculated explicitly, as well as the geometry of the source in terms of the relativistic multipole moments. The total mass of different configurations is also calculated, it is shown to be equal to the monopole of the exterior solution.

  12. Fragmentation of an axially impacted slender rod

    Science.gov (United States)

    Ji, W.; Waas, A. M.

    2010-02-01

    Motivated by experimental results on the dynamic buckling and fragmentation of a vertical column impacted by a falling mass, results from an analytical model for dynamic buckling which considers the dynamic interaction between the axial column deformation and the out-of-plane buckling displacements are used to interpret the fragmentation process and the resulting fragment lengths. It is shown that a critical time exists for the rod to undergo fragmentation. At this critical time, the rod deforms in a modulated pattern of waves, setting up the stage for the ensuing fragmentation as a result of induced large curvatures that exceed the critical bending strain of the rod material. The resulting fragment length distributions, which show two characteristics peaks at \\frac{\\lambda}{2} and \\frac{\\lambda}{4} , where λ is a characteristic half-wavelength, are found to compare favorably with the experimental results.

  13. Acoustic horizons in axially symmetric relativistic accretion

    CERN Document Server

    Abraham, H; Das, T K; Abraham, Hrvoje; Bilic, Neven; Das, Tapas K.

    2006-01-01

    Transonic accretion onto astrophysical objects is a unique example of analogue black hole realized in nature. In the framework of acoustic geometry we study axially symmetric accretion and wind of a rotating astrophysical black hole or of a neutron star assuming isentropic flow of a fluid described by a polytropic equation of state. In particular we analyze the causal structure of multitransonic configurations with two sonic points and a shock. Retarded and advanced null curves clearly demonstrate the presence of the acoustic black hole at regular sonic points and of the white hole at the shock. We calculate the analogue surface gravity and the Hawking temperature for the inner and the outer acoustic horizons.

  14. Dynamics of Flapping Flag in Axial Flow

    Science.gov (United States)

    Abderrahmane, Hamid Ait; Fayed, Mohamed; Gunter, Amy-Lee; Paidoussis, Michael P.; Ng, Hoi Dick

    2010-11-01

    We investigate experimentally the phenomenon of the flapping of a flag, placed within a low turbulent axial flow inside a small scale wind tunnel test section. Flags of different sizes and flexural rigidities were used. Image processing technique was used and the time series of a given point on the edge of the flag was analyzed. The stability condition of the flag was obtained and compared to the recent theoretical models and numerical simulations. Afterwards, the nonlinear dynamics of the flapping was investigated using nonlinear time series method. The nonlinear dynamics is depicted in phase space and the correlation dimension of the attractors is determined. On the basis of observations made in this study, some conclusions on the existing models were drawn.

  15. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    The objects of this invention are first to reduce the time required to obtain statistically significant data in trans-axial tomographic radioisotope scanning using a scintillation camera. Secondly, to provide a scintillation camera system to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a known radiation source without sacrificing spatial resolution. Thirdly to reduce the scanning time without loss of image clarity. The system described comprises a scintillation camera detector, means for moving this in orbit about a cranial-caudal axis relative to a patient and a collimator having septa defining apertures such that gamma rays perpendicular to the axis are admitted with high spatial resolution, parallel to the axis with low resolution. The septa may be made of strips of lead. Detailed descriptions are given. (U.K.)

  16. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    The principal problem in trans-axial tomographic radioisotope scanning is the length of time required to obtain meaningful data. Patient movement and radioisotope migration during the scanning period can cause distortion of the image. The object of this invention is to reduce the scanning time without degrading the images obtained. A system is described in which a scintillation camera detector is moved to an orbit about the cranial-caudal axis relative to the patient. A collimator is used in which lead septa are arranged so as to admit gamma rays travelling perpendicular to this axis with high spatial resolution and those travelling in the direction of the axis with low spatial resolution, thus increasing the rate of acceptance of radioactive events to contribute to the positional information obtainable without sacrificing spatial resolution. (author)

  17. Optical Tomography of Polydisperse Dry Foam

    Science.gov (United States)

    Chieco, Anthony; Feitosa, Klebert; Korda, P. T.; Roth, A. E.; Durian, D. J.

    2011-11-01

    Dry foam is a disordered packing of bubbles that distort into familiar polyhedral shapes. We have implemented a method that uses optical axial tomography to reconstruct the internal structure of a dry foam in three dimensions. The technique consists of taking a series of photographs of the dry foam against a uniformly illuminated background at successive angles. By summing the projections we create images of the cross section of the foam and analyze them to locate the Plateau borders and vertices. The vertices are then connected according to Plateau's rules to reconstruct the internal structure of the foam. Using this technique we are able to visualize a large number of bubbles of real 3D foams and obtain statistics of faces and edges. We gratefully acknowledge support from DOD-ASSURE/NSF-REU grant # DMR-0851367.

  18. Computed tomography findings in convergent strabismus fixus

    International Nuclear Information System (INIS)

    X-ray computed tomography (CT) of the eyeball and orbit revealed the cause of eye movement disorder in convergent strabismus fixus. The findings suggest that the disease can be diagnosed and treated at an early stage. Twelve cases of progressive esotropia with high myopia and 20 cases with normal visual acuity served as subjects in this study. The CT slice was parallel to the German horizontal plane, and the lens and medial and lateral rectus muscles were scanned. The average axial length of the affected eyes was significantly longer than in normal eyes. In progressive esotropia, the characteristic CT findings are an elongated eyeball, mechanical contact between the eyeball and lateral wall of the orbit, and a downward displacement of the lateral rectus muscle. Thus, it is reasonable to conclude that eye movement disorder in convergent strabismus fixus results from weakness of the lateral rectus muscle which has been displaced downward due to compression of the eyeball against the orbital wall. (author)

  19. Advances in positron tomography for oncology

    International Nuclear Information System (INIS)

    Development of PET instrumentation over the past 42 years has moved from simple dual-detector coincidence scanners, to proposed systems having 60,000 detectors and simultaneous coverage of 15-cm regions of the body with spatial resolutions better than 4 mm. The principal determinants of positron emission tomography (PET) instrumentation advances are positron range, noncollinearity of the annihilation photons, scattering, random event rates, detector size, efficiency, speed and light output; capability to correct for depth of crystal interaction, attenuation compensation, axial coverage, and rapid data analysis and presentation. While general-purpose systems with 2-mm resolution are expected, special-purpose PET devices are being built for breast and brain tumor studies with resolutions from 1.7 to 5 mm

  20. Computed tomography findings in convergent strabismus fixus

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Michitaka; Iwashige, Hiroyasu; Hayashi, Takao; Maruo, Toshio [Teikyo Univ., Tokyo (Japan). Faculty of Medicine

    1995-08-01

    X-ray computed tomography (CT) of the eyeball and orbit revealed the cause of eye movement disorder in convergent strabismus fixus. The findings suggest that the disease can be diagnosed and treated at an early stage. Twelve cases of progressive esotropia with high myopia and 20 cases with normal visual acuity served as subjects in this study. The CT slice was parallel to the German horizontal plane, and the lens and medial and lateral rectus muscles were scanned. The average axial length of the affected eyes was significantly longer than in normal eyes. In progressive esotropia, the characteristic CT findings are an elongated eyeball, mechanical contact between the eyeball and lateral wall of the orbit, and a downward displacement of the lateral rectus muscle. Thus, it is reasonable to conclude that eye movement disorder in convergent strabismus fixus results from weakness of the lateral rectus muscle which has been displaced downward due to compression of the eyeball against the orbital wall. (author).

  1. Axially symmetric Lorentzian wormholes in general relativity

    International Nuclear Information System (INIS)

    The field equations of Einstein's theory of general relativity, being local, do not fix the global structure of space-time. They admit topologically non-trivial solutions, including spatially closed universes and the amazing possibility of shortcuts for travel between distant regions in space and time - so-called Lorentzian wormholes. The aim of this thesis is to (mathematically) construct space-times which contain traversal wormholes connecting arbitrary distant regions of an asymptotically flat or asymptotically de Sitter universe. Since the wormhole mouths appear as two separate masses in the exterior space, space-time can at best be axially symmetric. We eliminate the non-staticity caused by the gravitational attraction of the mouths by anchoring them by strings held at infinity or, alternatively, by electric repulsion. The space-times are obtained by surgically grafting together well-known solutions of Einstein's equations along timelike hypersurfaces. This surgery naturally concentrates a non-zero stress-energy tensor on the boundary between the two space-times which can be investigated by using the standard thin shell formalism. It turns out that, when using charged black holes, the provided constructions are possible without violation of any of the energy conditions. In general, observers living in the axially symmetric, asymptotically flat (respectively asymptotically de Sitter) region axe able to send causal signals through the topologically non-trivial region. However, the wormhole space-times contain closed timelike curves. Because of this explicit violation of global hyperbolicity these models do not serve as counterexamples to known topological censorship theorems. (author)

  2. Transverse vibration characteristics of axially moving viscoelastic plate

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yin-feng; WANG Zhong-min

    2007-01-01

    The dynamic characteristics and stability of axially moving viscoelastic rectangular thin plate are investigated. Based on the two dimensional viscoelastic differential constitutive relation, the differential equations of motion of the axially moving viscoelastic plate are established. Dimensionless complex frequencies of an axially moving viscoelastic plate with four edges simply supported, two opposite edges simply supported and other two edges clamped are calculated by the differential quadrature method. The effects of the aspect ratio, moving speed and dimensionless delay time of the material on the transverse vibration and stability of the axially moving viscoelastic plate are analyzed.

  3. Spectral-domain optical coherence tomography of macula in myopia.

    Science.gov (United States)

    Choovuthayakorn, Janejit; Laowong, Taksaorn; Watanachai, Nawat; Patikulsila, Direk; Chaikitmongkol, Voraporn

    2016-06-01

    The aim of this study is to determine the associations between regional macular thickness and gender, age, axial length, and degree of myopia in young and middle-aged healthy myopic eyes. One hundred and seventy-one subjects with -0.5 diopters of myopia or worse underwent prospective macular thickness measurement by Spectralis spectral-domain optical coherence tomography. Subjects' mean age was 32.40 ± 8.25 years (range 18 to 49 years), with 45 % being male. The mean degree of myopia was -4.57 ± 3.52 diopters, with a mean axial length of 25.09 ± 1.67 mm. Multivariate regression analysis demonstrated significantly thicker central (mean 9.13 µm thicker) and inner subfields (mean 8.55 µm thicker) in males (P values were <0.001 and 0.002, respectively). In addition, in both genders, for each millimeter of increased axial length, the central subfield thickness increased by 2.11 µm, the inner subfield decreased by 2.25 µm, and the outer subfield decreased by 3.62 µm (P values were 0.010, <0.001, and <0.001, respectively). Factors including gender and axial length affect baseline regional macular thickness in young and middle-age myopic subjects. The central subfield and inner subfield were affected by both gender and axial length, while the outer subfield was affected only by axial length. The macular thickness of myopic subjects with macular disease should be interpreted in light of these factors. PMID:26290135

  4. Green's Functions in Axial and Lorentz-type Gauges and Application to The Axial Pole Prescription and The Wilson Loop

    OpenAIRE

    Joglekar, Satish D.

    2000-01-01

    We summarize the work done in connecting Green's functions in a different classes of gauges and its applications to the problems in the axial gauges.The procedure adopted uses finite field-dependent BRS [FFBRS] transformations to connect axial and the Lorentz type gauges.These transformations preserve the vacuum expectation of gauge-invariant observables explicitly. We discuss the applications of these ideas to the axial gauge pole problem and to the preservation of the Wilson loop and the th...

  5. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Videos related to Computed Tomography (CT) - Head About this Site RadiologyInfo.org is produced by: Please note ... you can search the ACR-accredited facilities database . This website does not provide cost information. The costs ...

  6. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available ... Images related to Computed Tomography (CT) - Sinuses About this Site RadiologyInfo.org is produced by: Please note ... you can search the ACR-accredited facilities database . This website does not provide cost information. The costs ...

  7. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Sinuses ...

  8. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Head ...

  9. Three dimensional time reversal optical tomography

    Science.gov (United States)

    Wu, Binlin; Cai, W.; Alrubaiee, M.; Xu, M.; Gayen, S. K.

    2011-03-01

    Time reversal optical tomography (TROT) approach is used to detect and locate absorptive targets embedded in a highly scattering turbid medium to assess its potential in breast cancer detection. TROT experimental arrangement uses multi-source probing and multi-detector signal acquisition and Multiple-Signal-Classification (MUSIC) algorithm for target location retrieval. Light transport from multiple sources through the intervening medium with embedded targets to the detectors is represented by a response matrix constructed using experimental data. A TR matrix is formed by multiplying the response matrix by its transpose. The eigenvectors with leading non-zero eigenvalues of the TR matrix correspond to embedded objects. The approach was used to: (a) obtain the location and spatial resolution of an absorptive target as a function of its axial position between the source and detector planes; and (b) study variation in spatial resolution of two targets at the same axial position but different lateral positions. The target(s) were glass sphere(s) of diameter ~9 mm filled with ink (absorber) embedded in a 60 mm-thick slab of Intralipid-20% suspension in water with an absorption coefficient μa ~ 0.003 mm-1 and a transport mean free path lt ~ 1 mm at 790 nm, which emulate the average values of those parameters for human breast tissue. The spatial resolution and accuracy of target location depended on axial position, and target contrast relative to the background. Both the targets could be resolved and located even when they were only 4-mm apart. The TROT approach is fast, accurate, and has the potential to be useful in breast cancer detection and localization.

  10. Informationally Incomplete Quantum Tomography

    OpenAIRE

    Teo, Yong Siah; Rehacek, Jaroslav; Hradil, Zdenek

    2013-01-01

    In quantum-state tomography on sources with quantum degrees of freedom of large Hilbert spaces, inference of quantum states of light for instance, a complete characterization of the quantum states for these sources is often not feasible owing to limited resources. As such, the concepts of informationally incomplete state estimation becomes important. These concepts are ideal for applications to quantum channel/process tomography, which typically requires a much larger number of measurement se...

  11. Role of magnetic cusp for multiple axial potential structures (MAPS) formation

    International Nuclear Information System (INIS)

    Cusp like magnetic field profile in expanding helicon experimental system is studied for the formation of multiple axial potential structures (MAPS). Double layer like this potential structures formation in this kind of expanding helicon system produces thrusts along the axial direction. Observation of multiple ion beams is an indirect evidence for the formation of multiple double layers like potential structures. However, there is no such direct evidence available to identify the strength and location for the formation of these structures, in magnetic and geometric expanding helicon plasma systems. Transition from single to multiple axial potential structures is observed by varying the magnetic field topology from diverging to cusp. A localized threshold density is required to maintain the steady state potential structure inside the bulk plasma. Cusp like magnetic field profile inside the expansion controls this downstream density rise and beyond the threshold limit of this density rise, the second potential structure is formed. In this presentation, quantitative discussion will be presented to understand the root causes to maintain the critical density for the formation of MAPS and the mechanism responsible for maintaining this density inhomogeneity in these expanding plasmas. (author)

  12. Evaluation of superior vena cava syndrome by axial CT and CT phlebography

    International Nuclear Information System (INIS)

    Transverse axial computed tomography (CT) has been combined with CT digital phlebography to study nine patients with superior vena cava syndrome. Six were due to malignancy, two were secondary to benign disease, and one was a paraneoplastic manifestation. This combined CT approach successfully identified the abnormal morphology of the superior vena cava, demonstrating external compression, encasement, or intraluminal thrombus in all patients and the collateral venous channels in eight. This technique is a rapid, informative, and cost-effective method for the workup of superior vena cava syndrome. The CT digital phlebogram, however, is not successful in regularly and optimally opacifying the normal superior vena cava because of the limited amount of contrast material, dilution effect of the nonopacified incoming flow from the jugular and azygos veins, and the lack of image enhancement from the CT digital scanograms

  13. Evaluation of superior vena cava syndrome by axial CT and CT phlebography

    Energy Technology Data Exchange (ETDEWEB)

    Moncada, R.; Cardella, R.; Demos, T.C.; Churchill, R.J.; Cardoso, M.; Love, L.; Reynes, C.J.

    1984-10-01

    Transverse axial computed tomography (CT) has been combined with CT digital phlebography to study nine patients with superior vena cava syndrome. Six were due to malignancy, two were secondary to benign disease, and one was a paraneoplastic manifestation. This combined CT approach successfully identified the abnormal morphology of the superior vena cava, demonstrating external compression, encasement, or intraluminal thrombus in all patients and the collateral venous channels in eight. This technique is a rapid, informative, and cost-effective method for the workup of superior vena cava syndrome. The CT digital phlebogram, however, is not successful in regularly and optimally opacifying the normal superior vena cava because of the limited amount of contrast material, dilution effect of the nonopacified incoming flow from the jugular and azygos veins, and the lack of image enhancement from the CT digital scanograms.

  14. Single Photon Emission Tomography Imaging in Parkinsonian Disorders: A Review

    OpenAIRE

    Acton, Paul D.; P. David Mozley

    2000-01-01

    Parkinsonian symptoms are associated with a number of neurodegenerative disorders, such as Parkinson’s disease, multiple system atrophy and progressive supranuclear palsy. Pathological evidence has shown clearly that these disorders are associated with a loss of neurons, particularly in the nigrostriatal dopaminergic pathway. Positron emission tomography (PET) and single photon emission tomography (SPECT) now are able to visualise and quantify changes in cerebral blood flow, glucose metabolis...

  15. Fabrication and Experimental Analysis of Axially Oriented Nanofibers.

    Science.gov (United States)

    Aphale, Ashish N; Mahakalkar, Kapil; Macwan, Isaac G; Mukerji, Ishita; Cox, Paris J; Mahapatra, Manoj; Singh, Prabhakar; Ajayan, Pulickel M; Patra, Prabir K

    2016-03-01

    A novel design of a laboratory built axially rotating collector (ARC) having capability to align electrospun nanofibers have been described. A detailed morphological comparison of such nanofibers orientation and their geometry is done using scanning electron microscopy (SEM). For comparison various polymeric solutions were electrospun on conventional static collector as well as ARC. The average diameter of polyvinyl alcohol (PVA) nanofibers was found to be 250 nm while polycaprolactone (PCL) nanofibers were found to be within a range of 600-800 nm. Conducting nanoparticles such as graphene and multi-walled carbon nanotubes (MWNTs) mixed with polymer solutions shown to have a significant influence on the overall geometry of these nanofibers and their diameter distribution. It is evident from the SEM analysis that both graphene and MWNTs in polymer solution play a crucial role in achieving a uniform diameter of nanofibers. Lastly, the formation of the aligned nanofibers using ARC has been mathematically modeled and the electromagnetic field governing the process has been simulated. PMID:27455687

  16. Pre-bilaterian origin of the blastoporal axial organizer

    Science.gov (United States)

    Kraus, Yulia; Aman, Andy; Technau, Ulrich; Genikhovich, Grigory

    2016-01-01

    The startling capacity of the amphibian Spemann organizer to induce naïve cells to form a Siamese twin embryo with a second set of body axes is one of the hallmarks of developmental biology. However, the axis-inducing potential of the blastopore-associated tissue is commonly regarded as a chordate feature. Here we show that the blastopore lip of a non-bilaterian metazoan, the anthozoan cnidarian Nematostella vectensis, possesses the same capacity and uses the same molecular mechanism for inducing extra axes as chordates: Wnt/β-catenin signaling. We also demonstrate that the establishment of the secondary, directive axis in Nematostella by BMP signaling is sensitive to an initial Wnt signal, but once established the directive axis becomes Wnt-independent. By combining molecular analysis with experimental embryology, we provide evidence that the emergence of the Wnt/β-catenin driven blastopore-associated axial organizer predated the cnidarian-bilaterian split over 600 million years ago. PMID:27229764

  17. Retinal Optical Coherence Tomography Imaging

    Science.gov (United States)

    Drexler, Wolfgang; Fujimoto, James G.

    The eye is essentially transparent, transmitting light with only minimal optical attenuation and scattering providing easy optical access to the anterior segment as well as the retina. For this reason, ophthalmic and especially retinal imaging has been not only the first but also most successful clinical application for optical coherence tomography (OCT). This chapter focuses on the development of OCT technology for retinal imaging. OCT has significantly improved the potential for early diagnosis, understanding of retinal disease pathogenesis, as well as monitoring disease progression and response to therapy. Development of ultrabroad bandwidth light sources and high-speed detection techniques has enabled significant improvements in ophthalmic OCT imaging performance, demonstrating the potential of three-dimensional, ultrahigh-resolution OCT (UHR OCT) to perform noninvasive optical biopsy of the living human retina, i.e., the in vivo visualization of microstructural, intraretinal morphology in situ approaching the resolution of conventional histopathology. Significant improvements in axial resolution and speed not only enable three-dimensional rendering of retinal volumes but also high-definition, two-dimensional tomograms, topographic thickness maps of all major intraretinal layers, as well as volumetric quantification of pathologic intraretinal changes. These advances in OCT technology have also been successfully applied in several animal models of retinal pathologies. The development of light sources emitting at alternative wavelengths, e.g., around #1,060 nm, not only enabled three-dimensional OCT imaging with enhanced choroidal visualization but also improved OCT performance in cataract patients due to reduced scattering losses in this wavelength region. Adaptive optics using deformable mirror technology, with unique high stroke to correct higher-order ocular aberrations, with specially designed optics to compensate chromatic aberration of the human eye, in

  18. Test Setup for Axially Loaded Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina

    The test setup for testing axially static and cyclic loaded piles in sand is described in the following. The purpose for the tests is to examine the tensile capacity of axially loaded piles in dense fully saturated sand. The pile dimensions are chosen to resemble full scale dimension of piles used...

  19. An Unbroken Axial-Vector Current Conservation Law

    Science.gov (United States)

    Sharafiddinov, Rasulkhozha S.

    2016-04-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space in which a neutrino is characterized by left as well as by right space-time coordinates. Therefore, it is not surprising that whatever the main purposes experiments about a quasielastic axial-vector mass say in favor of an axial-vector mirror Minkowski space-time.

  20. Improved axial flux shape generator for quick DNB test

    International Nuclear Information System (INIS)

    Axial power shapes that develop during power maneuvering in pressurized water reactors must be analyzed to ensure that adequate margin to avoid departure from nucleate boiling (DNB) is maintained during these transients. In order to reduce the number of flux shapes that need to be analyzed in detail to determine DNB ratio (DNBR), often generic axial flux shapes are analyzed and Maximum Allowable Peaking (MAP) limits are determined to conservatively filter those actual axial power shapes that are clearly safe. Current generic MAP limits, obtained for axial flux shapes, generated by a two-parameter based axial flux shape generator, are overly conservative for some power shapes and nonconservative for others leading to unnecessary operational restrictions on conservative cases. A penalty is imposed on nonconservative cases. In order to reduce the number of overly conservative and nonconservative cases, the authors have developed a new generic axial power shape generator, that is based on three parameters. Generic MAP limits have been developed for the new axial flux shape generator and tested using real flux shapes by plotting the percent deviation of MAP limits for generic flux shapes from the corresponding value for actual flux shapes. New axial flux shape generator, which is clearly superior as it leads to significantly lower percent deviation, will lead to reduced man-hours for detailed DNBR analyses and remove some of the unnecessary operational restrictions imposed by the old flux shape generator

  1. A new approach to radial and axial gauges

    Energy Technology Data Exchange (ETDEWEB)

    Weigert, H.; Heinz, U. (Regensburg Univ. (Germany). Inst. fuer Theoretische Physik)

    1992-10-01

    We develop a new path integral formulation of QCD in radial and axial gauges. This formalism yields free propagators which are free of gauge poles. We find that radial gauges are ghost free. In axial gauges ghosts cannot generally be excluded from the formalism due to the need to fix the residual gauge freedom. (orig.).

  2. Study of a new airfoil used in reversible axial fans

    Science.gov (United States)

    Li, Chaojun; Wei, Baosuo; Gu, Chuangang

    1991-01-01

    The characteristics of the reverse ventilation of axial flow are analyzed. An s shaped airfoil with a double circular arc was tested in a wind tunnel. The experimental results showed that the characteristics of this new airfoil in reverse ventilation are the same as those in normal ventilation, and that this airfoil is better than the existing airfoils used on reversible axial fans.

  3. Computed tomography of juvenile nasopharyngeal angiofibroma

    International Nuclear Information System (INIS)

    It is well known that computed tomography (CT) is useful in detecting accurately the location, extent, erosion and relationship of angiofibroma to surrounding structures such as pterygopalation fossa. It is well known that computed tomography (CT) is useful in detecting accurately the location, sphenoid sinus, and etc. CT of 20 patients with juvenile angiofibroma, which were examined for 5 yeas from February, 1979 to May, 1984 at Department of Radiology, Seoul National University Hospital, were retrospectively analyzed. The results were as follows: 1. All 20 patients of juvenile angiofibroma had tumors in nasopharynx and posterior nasal cavity showing homogeneously dense-enhancing soft tissue mass on CT. There was extension of the tumor from nasopharynx and posterior nasal cavity into paranasal sinus (60%, 12/20), pterygopalatine fossa (55%, 11/20), infratemporal fossa (30%, 6/20), posterior orbit (10%, 2/20) and cranial cavity (15%, 3/20). 2. Angiogrpahy usually adds little diagnostic information, but is still needed to identify the precise source of blood supply to the tumor, and to perform the pre-operative embolization. The use of CT has deferred angiography until just before surgery, permitting embolization at optimal time. 3. CT is almost always necessary to reveal accurately the full extent of the tumor, especially intracranial space in the axial and coronal planes with contrast enhancement. CT is useful both in diagnosis as a guide to angiography and in planning the adequate therapy of juvenile angiofibroma

  4. Multimode interaction in axially excited cylindrical shells

    Directory of Open Access Journals (Sweden)

    Silva F. M. A.

    2014-01-01

    Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.

  5. Diagnosis of spondyloarthritis of the axial skeleton

    International Nuclear Information System (INIS)

    Conventional radiography is used as the first-line imaging test in evaluating the axial skeleton for manifestations of spondyloarthritis, which is a cover term for five entities: ankylosing spondylitis, psoriatric spondyloarthritis, reactive arthritis, enteropathic arthritis, and undifferentiated spondyloarthritis. However, as it often takes many years from the onset of clinical symptoms and the first appearance of radiographic changes, a cross-sectional imaging is warranted (CT and/or MRI) for early diagnosis. MRI sensitively detects early inflammatory stages of spondyloarthritis and can thus fill the gap by markedly reducing the interval between initial symptoms and diagnosis. The aim of this article is to show that all manifestations and forms of spondyloarthritis share the same pathogenetic inflammatory pattern, namely a mixture of bone destruction and bone proliferation: enthesis - enthesitis - enthesiophyte. An enthesis in the true sense is a fibrocartilaginous junction (uncalcified fibrocartilage - tidemark - calcified fibrocartilage) between a tendon, ligament, joint capsule, or fascia and bone. The sacroiliac joint is a special form, a so-called articular fibrocartilaginous enthesis. A wide range of images - including radiographs, CT scans, and MR images - will be presented to provide a comprehensive picture of the entheseal manifestations and inflammatory patterns of the sacroiliac joints, vertebral endplates and ridges, facet joints, costovertebral junctions, and spinal ligaments in spondyloarthritis. (orig.)

  6. Analysis of SONACO axial cooling experiments

    International Nuclear Information System (INIS)

    The SONACO test rig contained a sodium-cooled, electrically heated 37-pin bundle. On this rig, a series of forced, mixed and natural convection experiments have been performed with the aim of contributing to the understanding of thermal-hydraulic phenomena and providing data for code validation for a subassembly at decay heat power level with low flow or stagnant coolant. The test section and especially the heater pins were equipped with an extensive number of chromel-alumel thermocouples. In addition, special permanent-magnet probes were used for measuring local velocities. In this paper we give a survey of results from axial cooling experiments, where heat was removed by natural convection to a cooling coil situated in the coolant channel (plenum) above the bundle. The experimental conditions led to turbulent convection with a slowly varying, large scale flow pattern. It is shown that a power tilt in the bundle reduces these fluctuations but does not eliminate them. For the uniformly heated bundle, aglebraic expressions for the average turbulent heat flux as well as for temperature and velocity fluctuations are derived from a second-moments model and compared with experimental data. Furthermore, heat transfer in the plenum and the consequences of the SONACO experiments for the coolability of reactor fuel elements under loss-of-flow conditions are discussed. ((orig.))

  7. Axial change in semi-leptonic processes

    International Nuclear Information System (INIS)

    According to a general argument the time component AOof the axial current should have a large exchange current Aexch0due to a soft-pion exchange diagram the structure and magnitude of which are dictated by current algebra and the low-energy theorem. This implies that Aexch0carries valuable information on the role of chiral symmetry in nuclear medium, and many theoretical and experimental studies have been devoted to Aexch0 in the recent years. My talk surveys the latest developments in these studies. I first review the current status2 of analysis of the relevant Β decay data, paying particular attention to the assessment of nuclear physics uncertainties. I then discuss the observed extra enhancement of Aexch0 over the soft-pion prediction. Two possible explanations to this problem have been reported in the literature: (1) contributions of heavy- meson exchange processes; (2) higher-order terms in chiral perturbation expansion. I review critically these two different approaches and discuss a possible interrelation between them. Finally, I touch upon the relevance of Aexch0 to the in-medium value of the pseudoscalar form factor gp

  8. Axially Loaded Behavior of Driven PC Piles

    Science.gov (United States)

    Hsu, Shih-Tsung

    2010-05-01

    To obtain a fair load-settlement curve of a driven pile, and to evaluate the ultimate pile capacity more accurately, a numerical model was created to simulate the ground movements during a pile being driven. After the procedure, the axially loaded behaviors of the piles in silty sand were analyzed. The numerical results are compared with those results by full scale pile load tests. It was found, although the loads added on the tested piles are different from those by the numerical analyses which applied displacement increments on piles, the load-settlement behaviors of piles calculated from the numerical model were close to those measured from field tests before the piles stressed to peak. Total load, shaft friction, and point bearing do not reach peak values at the same pile settlement; furthermore, the point bearing slowly increases all the while, with no peak. However, the point bearing only contributes 10˜20% of ultimate pile capacity. No matter which relative density of silty sand, pile diameter, and pile length increased, ultimate pile capacity increased as well.

  9. The Klinger hot gas double axial valve

    International Nuclear Information System (INIS)

    The Klinger hot gas valve is a medium controlled double axial valve with advanced design features and safety function. It was first proposed by Klinger early in 1976 for the PNP-Project as a containment shut-off for hot helium (918 deg. C and 42 bar), because a market research has shown that such a valve is not state of present techniques. In the first stage of development a feasibility study had to be made by detailed design, calculation and by basic experiments for key components in close collaboration with Interatom/GHT. This was the basis for further design, calculation, construction and experimental work for such a valve prototype within the new development contract. The stage of knowledge to that time revealed the following key priority development areas: Finite element stress analysis for the highly stressed high temperature main components; development of an insulation layout; Detailed experimental tests of functionally important structural components or units of the valve, partly at Klingers (gasstatic bearings, flexible metallic sealing element, aerodynamic and thermohydraulic tests), partly at Interatom (actuator unit and also gasstatic bearings), partly at HRB in Juelich (flexible metallic sealing system, aerodynamic and thermohydraulic tests); Design of a test valve for experimental work in the KVK (test circuit at Interatom) for evaluation of temperature distribution and reliability of operation; Design of a prototype and extensive testing in the KVK

  10. Axial channeling of boron ions into silicon

    Science.gov (United States)

    La Ferla, A.; Galvagno, G.; Raineri, V.; Setola, R.; Rimini, E.; Carbera, A.; Gasparotto, A.

    1992-04-01

    Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5 × 10 11 and 1 × 10 15 atoms/cm 2. The axial channeling concentration profiles of implanted B + were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energ dependence of the electronic stopping power is given by Sc = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles.

  11. Axial channeling of boron ions into silicon

    International Nuclear Information System (INIS)

    Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x1011 and 1x1015 atoms/cm2. The axial channeling concentration profiles of implanted B+ were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energy dependence of the electronic stopping power is given by Se = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.)

  12. Axial channeling of boron ions into silicon

    Energy Technology Data Exchange (ETDEWEB)

    La Ferla, A.; Galvagno, G. (Ist. di Tecnologie e Metodologie per la Microelettronica, CNR, Dipt. di Fisica, Catania (Italy)); Raineri, V.; Setola, R.; Rimini, E. (Dipt. di Fisica, Univ. di Catania (Italy)); Carnera, A.; Gasparotto, A. (Dipt. di Fisica, Univ. di Padova (Italy))

    1992-04-01

    Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x10{sup 11} and 1x10{sup 15} atoms/cm{sup 2}. The axial channeling concentration profiles of implanted B{sup +} were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, S{sub c}, was extracted from the experimental maximum ranges for the (100) and (110) axis. The energy dependence of the electronic stopping power is given by S{sub e} = KE{sup p} with p{sub (100)} = 0.469{+-}0.010 and p{sub (110)} = 0.554{+-}0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.).

  13. Ultrahigh resolution optical coherence tomography with femtosecond Ti:sapphire laser and photonic crystal fiber

    Institute of Scientific and Technical Information of China (English)

    XUE Ping; James G FUJIMOTO

    2008-01-01

    Optical coherence tomography (OCT) with ultrahigh axial resolution was achieved by the super-contin- uum generated by coupling femtosecond pulses from a commercial Ti :sapphire laser into an air-silica microstructure fiber. The visible spectrum of the super-continuum from 450 to 700 nm centered at 540 nm can be generated. A free-space axial OCT resolution of 0.64 IJm was achieved. The sensitivity of OCT system was 108 dB with incident light power 3 mW at sample, only 7dB below the theoretical limit. Subcellular OCT imaging was also demonstrated, showing great potential for biomedical application.

  14. Metastatic disease of the brain: extra-axial metastases (skull, dura, leptomeningeal) and tumour spread

    Energy Technology Data Exchange (ETDEWEB)

    Maroldi, Roberto; Ambrosi, Claudia; Farina, Davide [University of Brescia, Department of Radiology, Brescia, BS (Italy)

    2005-03-01

    Extra-axial intracranial metastases may arise through several situations. Hematogenous spread to the meninges is the most frequent cause. Direct extension from contiguous extra-cranial neoplasms, secondary invasion of the meninges by calvarium and skull base metastases, and migration along perineural or perivascular structures are less common. Leptomeningeal invasion gives rise to tumour cell dissemination by the cerebrospinal fluid (CSF), eventually leading to neoplastic coating of brain surfaces. Contrast-enhanced magnetic resonance (MR) imaging is complementary to CSF examinations and can be invaluable, detecting up to 50% of false-negative lumbar punctures. MR findings range from diffuse linear leptomeningeal enhancement to multiple enhancing extra-axial nodules, obstructive communicating and non-communicating hydrocephalus. Both calvarial and epidural metastases infrequently transgress the dura, which acts as a barrier against tumour spread. Radionuclide bone studies are still a valuable screening test to detect bone metastases. With computed tomography (CT) and MR, bone metastases extending intracranially and primary dural metastases show the characteristic biconvex shape, usually associated with brain displacement away from the inner table. Although CT is better in detecting skull base erosion, MR is more sensitive and provides more detailed information about dural involvement. Perineural and perivascular spread from head and neck neoplasms require thin-section contrast-enhanced MR. (orig.)

  15. Metastatic disease of the brain: extra-axial metastases (skull, dura, leptomeningeal) and tumour spread

    International Nuclear Information System (INIS)

    Extra-axial intracranial metastases may arise through several situations. Hematogenous spread to the meninges is the most frequent cause. Direct extension from contiguous extra-cranial neoplasms, secondary invasion of the meninges by calvarium and skull base metastases, and migration along perineural or perivascular structures are less common. Leptomeningeal invasion gives rise to tumour cell dissemination by the cerebrospinal fluid (CSF), eventually leading to neoplastic coating of brain surfaces. Contrast-enhanced magnetic resonance (MR) imaging is complementary to CSF examinations and can be invaluable, detecting up to 50% of false-negative lumbar punctures. MR findings range from diffuse linear leptomeningeal enhancement to multiple enhancing extra-axial nodules, obstructive communicating and non-communicating hydrocephalus. Both calvarial and epidural metastases infrequently transgress the dura, which acts as a barrier against tumour spread. Radionuclide bone studies are still a valuable screening test to detect bone metastases. With computed tomography (CT) and MR, bone metastases extending intracranially and primary dural metastases show the characteristic biconvex shape, usually associated with brain displacement away from the inner table. Although CT is better in detecting skull base erosion, MR is more sensitive and provides more detailed information about dural involvement. Perineural and perivascular spread from head and neck neoplasms require thin-section contrast-enhanced MR. (orig.)

  16. Quantitative analysis of cone photoreceptor distribution and its relationship with axial length, age, and early age-related macular degeneration.

    Directory of Open Access Journals (Sweden)

    Ryo Obata

    Full Text Available PURPOSE: It has not been clarified whether early age-related macular degeneration (AMD is associated with cone photoreceptor distribution. We used adaptive optics fundus camera to examine cone photoreceptors in the macular area of aged patients and quantitatively analyzed its relationship between the presence of early AMD and cone distribution. METHODS: Sixty cases aged 50 or older were studied. The eyes were examined with funduscopy and spectral-domain optical coherence tomography to exclude the eyes with any abnormalities at two sites of measurement, 2° superior and 5° temporal to the fovea. High-resolution retinal images with cone photoreceptor mosaic were obtained with adaptive optics fundus camera (rtx1, Imagine Eyes, France. After adjusting for axial length, cone packing density was calculated and the relationship with age, axial length, or severity of early AMD based on the age-related eye disease study (AREDS classification was analyzed. RESULTS: Patient's age ranged from 50 to 77, and axial length from 21.7 to 27.5 mm. Mean density in metric units and that in angular units were 24,900 cells/mm2, 2,170 cells/deg2 at 2° superior, and 18,500 cells/mm2, 1,570 cels/deg2 at 5° temporal, respectively. Axial length was significantly correlated with the density calculated in metric units, but not with that in angular units. Age was significantly correlated with the density both in metric and angular units at 2° superior. There was no significant difference in the density in metric and angular units between the eyes with AREDS category one and those with categories two or three. CONCLUSION: Axial length and age were significantly correlated with parafoveal cone photoreceptor distribution. The results do not support that early AMD might influence cone photoreceptor density in the area without drusen or pigment abnormalities.

  17. Optical coherence tomography for process control of laser micromachining.

    Science.gov (United States)

    Wiesner, Markus; Ihlemann, Jürgen; Müller, Heike H; Lankenau, Eva; Hüttmann, Gereon

    2010-03-01

    In situ surface imaging for nondestructive evaluation (NDE) by optical coherence tomography (OCT) before, during, and after ablative laser processing is presented. Furthermore, it is shown that the ability of in situ characterization is beneficial for samples such as optical fibers, which are difficult to handle in the standard analysis. Surface images taken by the OCT are compared with these common analysis tools such as scanning electron microscopy (SEM), reflected-light, and confocal microscopy. An axial resolution of approximately 126 nm for surface detection and a lateral resolution <2.5 microm are obtained and the potential of the setup to imaging structures with high aspect ratio is demonstrated. PMID:20370183

  18. Nano-sensitive optical coherence tomography

    Science.gov (United States)

    Alexandrov, Sergey A.; Subhash, Hrebesh M.; Zam, Azhar; Leahy, Martin

    2014-03-01

    Depth resolved label-free detection of structural changes with nanoscale sensitivity is an outstanding problem in the biological and physical sciences and has significant applications in both the fundamental research and healthcare diagnostics arenas. Here we experimentally demonstrate a novel label-free depth resolved sensing technique based on optical coherence tomography (OCT) to detect structural changes at the nanoscale. Structural components of the 3D object, spectrally encoded in the remitted light, are transformed from the Fourier domain into each voxel of the 3D OCT image without compromising sensitivity. Spatial distribution of the nanoscale structural changes in the depth direction is visualized in just a single OCT scan. This label free approach provides new possibilities for depth resolved study of pathogenic and physiologically relevant molecules in the body with high sensitivity and specificity. It offers a powerful opportunity for early diagnosis and treatment of diseases. Experimental results show the ability of the approach to differentiate structural changes of 30 nm in nanosphere aggregates, located at different depths, from a single OCT scan, and structural changes less than 30 nm in time from two OCT scans. Application for visualization of the structure of human skin in vivo is also demonstrated.Depth resolved label-free detection of structural changes with nanoscale sensitivity is an outstanding problem in the biological and physical sciences and has significant applications in both the fundamental research and healthcare diagnostics arenas. Here we experimentally demonstrate a novel label-free depth resolved sensing technique based on optical coherence tomography (OCT) to detect structural changes at the nanoscale. Structural components of the 3D object, spectrally encoded in the remitted light, are transformed from the Fourier domain into each voxel of the 3D OCT image without compromising sensitivity. Spatial distribution of the nanoscale

  19. Computed Tomography Imaging of the Topographical Anatomy of Canine Prostate

    International Nuclear Information System (INIS)

    AIM: To investigate the topographical anatomy of canine prostate gland by computed tomography (CT) for diagnostic imaging purposes. ÐœATERIAL AND METHODS: Seven clinically healthy mongrel male dogs at the age of 3−4 years and body weight of 10−15 kg were submitted to transverse computerized axial tomography (CAT) with cross section thickness of 5 mm. RESULTS: The CT image of canine prostate is visualized throughout the scans of the pelvis in the planes through the first sacral vertebra (S1) dorsally; the bodies of iliac bones laterally and cranially to the pelvic brim (ventrally). The body of prostate appears as an oval homogenous relatively hypo dense finding with soft tissue density. The gland is well differentiated from the adjacent soft tissues. CONCLUSION: By means of CT, the cranial part of prostate gland in adult dogs aged 3−4 years exhibited an abdominal localization. (author)

  20. Method of evaluation of diagnostics reference levels in computerized tomography

    International Nuclear Information System (INIS)

    Computerized tomography is a complex technique with several selectable exposition parameters delivering high doses to the patient. In this work it was developed a simple methodology to evaluate diagnostic reference levels in computerized tomography, using the concept of Multiple Scan Average Dose (MSAD), recently adopted by the Health Ministry. For evaluation of the MSAD, a dose distribution was obtained through a measured dose profile on the axial axis of a water phantom with thermoluminescence dosemeters, TLD-100, for different exam technique. The MSAD was evaluated hrough two distinct methods. First, it was evaluated by the integration of the dose profile of a single slice and, second, obtained by the integration on central slice of the profile of several slices. The latter is in of accordance with the ionization chamber method, suggesting to be the most practical method of dose evaluation to be applied in the diagnostic reference level assessment routine for CT, using TLDs. (author)

  1. Análisis de la fuerza axial en un transportador de sinfín // Analysis of axial force in a screw conveyor.

    Directory of Open Access Journals (Sweden)

    F. Aguilar Parés

    1999-01-01

    Full Text Available Durante el movimiento de un material en un transportador de sinfín surge una fuerza en dirección axial que influye en laselección de uno de los cojinetes de apoyo del equipo. En el artículo aparecen algunas soluciones constructivas que tienen encuentan la fuerza axial. Por otro lado se establece la relación entre la fuerza axial y el empuje axial y se precisa de quiendepende el sentido del empuje axial. Por último se propone un modelo matemático que relaciona la fuerza axial con la potenciarequerida por el equipo.Palabras claves: Transportador de sinf in, fuerza axial , empuje axial ._________________________________________________________________________AbstractDuring the movement of material in a screw conveyor surge a force in axial direction that influence in the selection of one ofthe equipment support bearings. Some constructive solutions appear in the article for considering the axial force. In the otherhand it is established the relation between axial force and axial thurst and it is precised whose direction thurst axial depend of.Finally it is proposed a mathematic model that relates the axial force with the power required by the equipment.Key words: Screw conveyor, axial force, axial thurst .

  2. An update on biomarkers in axial spondyloarthritis.

    Science.gov (United States)

    Prajzlerová, Klára; Grobelná, Kristýna; Pavelka, Karel; Šenolt, Ladislav; Filková, Mária

    2016-06-01

    Axial spondyloarthritis is a chronic inflammatory disease with the onset at a young age, and, if undiagnosed and untreated, it may result in permanent damage and lifelong disability. Rates of early diagnosis have improved, due in particular to the addition of magnetic resonance imaging into the diagnostic armamentaria; however, it is costly, not widely available, and requires experienced readers to interpret the findings. In addition to clinical measures and imaging techniques, biomarkers that will be described in this review may represent useful tools for diagnosis, monitoring disease activity and outcomes as well as therapeutic responses. Currently, HLA-B27 remains the best genetic biomarker for making a diagnosis, while CRP currently appears to be the best circulating measure for assessing disease activity, predicting structural progression and therapeutic response. Interestingly, key molecules in the pathogenesis of the disease and essential therapeutic targets, such as tumour necrosis factor (TNF)α, interleukin (IL)-17 and IL-23, show only limited association with disease characteristics or disease progression. Some genetic biomarkers and particularly anti-CD74 antibodies, may become a promising tool for the early diagnosis of axSpA. Further biomarkers, such as matrix metalloproteinases (MMP)-3, calprotectin (S100A8/9), vascular endothelial growth factor (VEGF), C-terminal telopeptide of type II collagen (CTX-II) or dickkopf-1 (DKK-1), are not sufficient to reflect disease activity, but may predict spinal structural progression. In addition, recent data have shown that monitoring calprotectin might represent a valuable biomarker of therapeutic response. However, all of these results need to be confirmed in large cohort studies prior to use in daily clinical practice. PMID:26851549

  3. Reactivity effects of nonuniform axial burnup distributions on spent fuel

    International Nuclear Information System (INIS)

    When conducting future criticality safety analyses on spent fuel shipping casks, burnup credit may play a significant role in determining the number of fuel assemblies that can be safely loaded into each cask. An important area in burnup credit analysis is the burnup variation along the length of the fuel assembly, which is determined by the location of the assembly in the reactor core and its residence time. A study of the effects of axial burnup distributions on reactivity has been conducted, using data from existing power plant fuel. Utilizing a one-dimensional, two-group diffusion code, named REALAX, the reactivity effects of axial burnup profiles have been calculated for various PWR fuel assemblies. The reactivity effects calculated by the code are defined in terms of k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup divided by k for a uniform axial burnup distribution at the assembly average burnup. Criticality safety specialists can take advantage of the quick-running code to determine axial effects of different assembly burnup profiles. In general, the positive reactivity effects of axial burnup distributions increase as burnup increases, though they do not increase faster than the overall decrease in reactivity due to burnup

  4. Reactivity effects of nonuniform axial burnup distributions on spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Leary, R.W. II; Parish, T.A. [Texas A & M Univ., College Station, TX (United States)

    1995-12-01

    When conducting future criticality safety analyses on spent fuel shipping casks, burnup credit may play a significant role in determining the number of fuel assemblies that can be safely loaded into each cask. An important area in burnup credit analysis is the burnup variation along the length of the fuel assembly, which is determined by the location of the assembly in the reactor core and its residence time. A study of the effects of axial burnup distributions on reactivity has been conducted, using data from existing power plant fuel. Utilizing a one-dimensional, two-group diffusion code, named REALAX, the reactivity effects of axial burnup profiles have been calculated for various PWR fuel assemblies. The reactivity effects calculated by the code are defined in terms of k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup divided by k for a uniform axial burnup distribution at the assembly average burnup. Criticality safety specialists can take advantage of the quick-running code to determine axial effects of different assembly burnup profiles. In general, the positive reactivity effects of axial burnup distributions increase as burnup increases, though they do not increase faster than the overall decrease in reactivity due to burnup.

  5. Ocean acoustic reverberation tomography.

    Science.gov (United States)

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  6. Practical Bayesian Tomography

    CERN Document Server

    Granade, Christopher; Cory, D G

    2015-01-01

    In recent years, Bayesian methods have been proposed as a solution to a wide range of issues in quantum state and process tomography. State-of- the-art Bayesian tomography solutions suffer from three problems: numerical intractability, a lack of informative prior distributions, and an inability to track time-dependent processes. Here, we solve all three problems. First, we use modern statistical methods, as pioneered by Husz\\'ar and Houlsby and by Ferrie, to make Bayesian tomography numerically tractable. Our approach allows for practical computation of Bayesian point and region estimators for quantum states and channels. Second, we propose the first informative priors on quantum states and channels. Finally, we develop a method that allows online tracking of time-dependent states and estimates the drift and diffusion processes affecting a state. We provide source code and animated visual examples for our methods.

  7. Neutron Computed Tomography

    International Nuclear Information System (INIS)

    Computed tomography is a non-destructive testing method which can visualize cross-section of materials based on their nuclear characteristics. In the previous work, X-ray was used as its radiation media. The aim of this experiment was to improve the computed tomography technique using neutron beam. For reconstructing the cross-section image of materials, a filtered back projection was used. Result indicated that a minimum hole shown was 3 mm in diameter using a black and white presentation. While using eight colour levels, a hole of 2 mm in diameter could be seen clearly. It is expected that neutron computed tomography can improve the results of non-destructive testing. (author). 5 refs., 6 figs

  8. Comparative evaluation of computed tomography for dental implants on the mandibular edentulous area

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Kyung Hoon; Jeong, Ho Gul; Park, Hyok; Park, Chang Seo; Kim, Kee Deog [Department of Oral and Maxillofacial Radiology, Oral Science Research Center, College of Dentistry, Yonsei University, Seoul (Korea, Republic of)

    2009-03-15

    The purpose of this study was to evaluate the clinical usefulness of the recently developed multi-detector computed tomography and cone beam computed tomography in pre-operative implant evaluation, by comparing them with the single detector computed tomography, already confirmed for accuracy in this area. Five partially edentulous dry human mandibles, with 1 X 1 mm gutta percha cones, placed in 5 mm intervals posterior to the mental foramen on each side of the buccal part of the mandible, were used in this study. They were scanned as follows: 1) Single detector computed tomography: slice thickness 1 mm, 200 mA, 120 kV 2) Multi-detector computed tomography: slice thickness 0.75 mm, 250 mA, 120 kV 3) Cone beam computed tomography: 15 mAs, 120 kV Axial images acquired from three computed tomographs were transferred to personal computer, and then reformatted cross-sectional images were generated using V-Implant 2.0 (CyberMed Inc., Seoul, Korea) software. Among the cross-sectional images of the gutta percha cone, placed in the buccal body of the mandible, the most precise cross section was selected as the measuring point and the distance from the most superior border of the mandibular canal to the alveolar crest was measured and analyzed 10 times by a dentist. There were no significant intraobserver differences in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). There were no significant differences among single detector computed tomography, multi-detector computed tomography and cone beam computed tomography in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). Multi-detector computed tomography and cone beam computed tomography are clinically useful in the evaluation of pre-operative site for mandibular dental implants, with consideration for radiation exposure dose and scanning time.

  9. Comparative evaluation of computed tomography for dental implants on the mandibular edentulous area

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate the clinical usefulness of the recently developed multi-detector computed tomography and cone beam computed tomography in pre-operative implant evaluation, by comparing them with the single detector computed tomography, already confirmed for accuracy in this area. Five partially edentulous dry human mandibles, with 1 X 1 mm gutta percha cones, placed in 5 mm intervals posterior to the mental foramen on each side of the buccal part of the mandible, were used in this study. They were scanned as follows: 1) Single detector computed tomography: slice thickness 1 mm, 200 mA, 120 kV 2) Multi-detector computed tomography: slice thickness 0.75 mm, 250 mA, 120 kV 3) Cone beam computed tomography: 15 mAs, 120 kV Axial images acquired from three computed tomographs were transferred to personal computer, and then reformatted cross-sectional images were generated using V-Implant 2.0 (CyberMed Inc., Seoul, Korea) software. Among the cross-sectional images of the gutta percha cone, placed in the buccal body of the mandible, the most precise cross section was selected as the measuring point and the distance from the most superior border of the mandibular canal to the alveolar crest was measured and analyzed 10 times by a dentist. There were no significant intraobserver differences in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). There were no significant differences among single detector computed tomography, multi-detector computed tomography and cone beam computed tomography in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). Multi-detector computed tomography and cone beam computed tomography are clinically useful in the evaluation of pre-operative site for mandibular dental implants, with consideration for radiation exposure dose and scanning time.

  10. Axial 3D region of interest reconstruction using weighted cone beam BPF/DBPF algorithm cascaded with adequately oriented orthogonal butterfly filtering

    Science.gov (United States)

    Tang, Shaojie; Tang, Xiangyang

    2016-03-01

    Axial cone beam (CB) computed tomography (CT) reconstruction is still the most desirable in clinical applications. As the potential candidates with analytic form for the task, the back projection-filtration (BPF) and the derivative backprojection filtered (DBPF) algorithms, in which Hilbert filtering is the common algorithmic feature, are originally derived for exact helical and axial reconstruction from CB and fan beam projection data, respectively. These two algorithms have been heuristically extended for axial CB reconstruction via adoption of virtual PI-line segments. Unfortunately, however, streak artifacts are induced along the Hilbert filtering direction, since these algorithms are no longer accurate on the virtual PI-line segments. We have proposed to cascade the extended BPF/DBPF algorithm with orthogonal butterfly filtering for image reconstruction (namely axial CB-BPP/DBPF cascaded with orthogonal butterfly filtering), in which the orientation-specific artifacts caused by post-BP Hilbert transform can be eliminated, at a possible expense of losing the BPF/DBPF's capability of dealing with projection data truncation. Our preliminary results have shown that this is not the case in practice. Hence, in this work, we carry out an algorithmic analysis and experimental study to investigate the performance of the axial CB-BPP/DBPF cascaded with adequately oriented orthogonal butterfly filtering for three-dimensional (3D) reconstruction in region of interest (ROI).

  11. Cervical computed tomography

    International Nuclear Information System (INIS)

    This book describes the possibilities of cervical computed tomography with the apparatus available at present. The normal anatomy of the cervical region as it appears in computed tomography is described with special regard to its compartimental structure and functional aspects; this is supplemented by anatomically normal measures obtained from cervical computed tomograms of 60 healthy individuals of different age and both sexes. The morphology of cervical anomalies obtained via CT and of the various acquired cervical disease processes is discussed and illustrated by means of the authors' own observations; the diagnostic value of the findings obtained by CT is discussed, a diagnosis is set up. (orig./MG)

  12. Tomography of solitons

    International Nuclear Information System (INIS)

    We develop the tomographic representation of wavefunctions which are solutions of the generalized nonlinear Schroedinger equation (NLSE) and show its connection with the Weyl-Wigner map. The generalized NLSE is presented in the form of a nonlinear Fokker-Planck-type equation for the standard probability distribution function (tomogram). In particular, this theory is applied to solitons, where tomograms for envelope bright solitons of a family of modified NLSEs are presented and numerically evaluated. Examples of symplectic tomography and Fresnel tomography of linear and nonlinear signals are discussed

  13. Emission tomography: Physical aspects

    International Nuclear Information System (INIS)

    Two different approaches have been followed: i/ tomography by single gamma-photon counting (SPC), using either conventional scintillation cameras or specially designed detector arrays. These systems use radionuclides which are readily available commercially (99 mTc, 131 I, 201 Tl); ii/ positron-emission tomography (ACD) which relies on the simultaneous and colinear emission of two 511 keV gamma photons, permitting a higher detection efficiency and effective 'electronic collimation'. These factors give good spatial resolution and quantitative precision. The principal positron-emitting isotopes 11 C, 13 N, 150 O can also serve as tracers in a very wide range of biological processes. (orig./VJ)

  14. Gravitational waves from the axial perturbations of hyperon stars

    Institute of Scientific and Technical Information of China (English)

    Wen De-Hua; Yan Jing; Liu Xue-Mei

    2012-01-01

    The eigen-frequencies of the axial w-mode oscillations of hyperon stars are examined.It is shown that as the appearance of hyperons softens the equation of state of the super-density matter,the frequency of gravitational waves from the axial w-mode of hyperon star becomes smaller than that of a traditional neutron star at the same stellar mass.Moreover,the eigenfrequencies of hyperon stars also have scaling universality.It is shown that the EURO thirdgeneration gravitational-wave detector has the potential to detect the gravitational-wave signal emitted from the axial w-mode oscillations of a hyperon star.

  15. Tensile Property of Bi-axial Warp Knitted Structure

    Institute of Scientific and Technical Information of China (English)

    沈为

    2003-01-01

    The tensile property of bi-axial warp knitted fabrics is tested and compared with that of the plain weave fabric. The results show that there are obvious differences between the tensile property of a bi-axial warp knitted fabric and that of a plain weave fabric.The former can give fuller play to the property of a high modulus yarn than the latter. The tensile strength of a bi-axial warp knitted fabric is linear with the number of yarns in the direction of force.

  16. The axial charges of the hidden-charm pentaquark states

    CERN Document Server

    Wang, Guang-Juan; Zhu, Shi-Lin

    2016-01-01

    With the chiral quark model, we have calculated the axial charges of the pentaquark states with $(I,I_3)=(\\frac{1}{2},\\frac{1}{2})$ and $J^{P}=\\frac{1}{2}^{\\pm},\\frac{3}{2}^{\\pm},\\frac{5}{2}^{\\pm}$. The $P_c$ states with the same $J^P$ quantum numbers but different color-spin-flavor configurations have very different axial charges, which encode important information on their underlying structures. For some of the $J^{P}=\\frac{3}{2}^{\\pm}$ or $\\frac{5}{2}^{\\pm}$ pentaquark states, their axial charges are much smaller than that of the proton.

  17. Effects of external axial magnetic field on fast electron propagation

    International Nuclear Information System (INIS)

    A scheme employing an external axial magnetic field is proposed to diagnose the intrinsic divergence of laser-generated fast electron beams, and this is studied numerically with hybrid simulations. The maximum beam radius of fast electrons increases with the initial divergence and decreases with the amplitude of the axial magnetic field. It is indicated that the intrinsic divergence of fast electrons can be inferred from measurements of the beam radius at different depth under the axial field. The proposed scheme here may be useful for future fast ignition experiments and in other applications of laser-generated fast electron beams.

  18. Dynamic Analysis of Axial Magnetic Forces for DVD Spindle Motors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The axial magnetic force, induced by the complicated flux linkage distribution from rotor magnet and stator slotted, is constructed by different relative heights and calculated by 3D finite element method (FEM) to analyze the dynamic characteristics for a DVD spindle motor. The axial magnetic force is designed to provide an axial stiffness and govern the natural frequency of the dynamic performance. According to the simulation results and experimental measurements, the dynamic behaviors are significantly improved with a variation of relative height of rotor magnet and stator slotted on a DVD spindle motor.

  19. A non-integral, axial-force measuring element

    Science.gov (United States)

    Ringel, M.; Levin, D.; Seginer, A.

    1989-10-01

    A new approach to the measurement of the axial force is presented. A nonintegral axial-force measuring element, housed within the wind-tunnel model, avoids the interactions that are caused by nonlinear elastic phenomena characteristic of integral balances. The new design overcomes other problems, such as friction, misalignment and relative motion between metric elements, that plagued previous attempts at separate measurement of the axial force. Calibration and test results prove the ability of the new approach to duplicate and even surpass the results of much more complicated and expensive integral balances. The advantages of the new design make it the best known solution for particular measurement problems.

  20. In vivo visualization of photoreceptor layer and lipofuscin accumulation in Stargardt’s disease and fundus flavimaculatus by high resolution spectral-domain optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Giuseppe Querques

    2009-12-01

    Full Text Available Giuseppe Querques, Rosy Prato, Gabriel Coscas, Gisèle Soubrane, Eric H SouiedDepartment of Ophthalmology, Hopital Intercommunal de Creteil, University Paris XII, FranceIntroduction: To assess photoreceptor (PR layer morphology in patients with Stargardt’s disease (STGD and fundus flavimaculatus (FFM using high resolution spectral domain optical coherence tomography (HD-OCT; OCT 4000 Cirrus, Humphrey-Zeiss, San Leandro, CA.Methods: This was a prospective observational case series. Sixteen consecutive patients with STGD and FFM underwent a complete ophthalmologic examination. Optical coherence tomography examination was performed with HD-OCT, a high-speed (27,000 axial scans per second OCT system using spectral/Fourier domain detection, with an axial image resolution of 5 µm.Results: A total of 31 eyes were included in the study. Transverse loss of the PR layer in the foveal region was shown by HD-OCT. Twenty eyes with clinically evident central atrophy had a disruption of either the Verhoeff‘s membrane (VM or the layer corresponding to the interface of inner segment (IS and outer segment (OS of PR in the foveal region. Among these eyes, 12/20 eyes had a loss of the PR layer (loss of both VM and IS-OS interface in the foveal region. Eleven eyes (11/31 without clinically evident central atrophy had an intact interface of IS and OS of PR centrally. Moreover, we observed hyperreflective deposits: type 1 lesions located within the retinal pigment epithelium (RPE layer and at the level of the outer segments of PR, and type 2 lesions located at the level of the outer nuclear layer and clearly separated from the RPE layer. Type 1 lesions alone were associated with absence of loss of the PR layer in the foveal region in all eyes; type 2 lesions were always associated with presence of type 1 lesions, and often (8/12 eyes associated with loss of the PR layer within the foveal region. Mean best-corrected visual acuity (BCVA was significantly

  1. AXIAL: a system for boiling water reactor fuel assembly axial optimization using genetic algorithms

    International Nuclear Information System (INIS)

    A system named AXIAL is developed based on the genetic algorithms (GA) optimization method, using the 3D steady state simulator code Core-Master-PRESTO (CM-PRESTO) to evaluate the objective function. The feasibility of this methodology is investigated for a typical boiling water reactor (BWR) fuel assembly (FA). The axial location of different fuel compositions is found in order to minimize the FA mean enrichment needed to obtain the cycle length under the safety constraints. Thermal limits are evaluated at the end of cycle using the Haling calculation; the hot excess reactivity and the shutdown margin at the beginning of cycle are also evaluated. The implemented objective function is very flexible and complete, incorporating all the thermal and reactivity limits imposed during fuel design analysis; furthermore, additional constraints can be easily introduced in order to obtain an improved solution. The results show a small improvement in the FA average enrichment obtained with the system related to the reference case that has been studied. The results show that the system converge to an optimal solution, it is observed that the mean fuel enrichment decreases while all the constraints are satisfied. A comparison was also performed using one-point and two-points crossover operator and the results of a sensitivity study for different mutation percentage are also showed

  2. Organ localization: Toward prospective patient-specific organ dosimetry in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Segars, W. P., E-mail: paul.segars@duke.edu; Rybicki, K.; Norris, Hannah; Samei, E. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Frush, D. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States)

    2014-12-15

    Purpose: With increased focus on radiation dose from medical imaging, prospective radiation dose estimates are becoming increasingly desired. Using available populations of adult and pediatric patient phantoms, radiation dose calculations can be catalogued and prospectively applied to individual patients that best match certain anatomical characteristics. In doing so, the knowledge of organ size and location is a required element. Here, the authors develop a predictive model of organ locations and volumes based on an analysis of adult and pediatric computed tomography (CT) data. Methods: Fifty eight adult and 69 pediatric CT datasets were segmented and utilized in the study. The maximum and minimum points of the organs were recorded with respect to the axial distance from the tip of the sacrum. The axial width, midpoint, and volume of each organ were calculated. Linear correlations between these three organ parameters and patient age, BMI, weight, and height were determined. Results: No statistically significant correlations were found in adult patients between the axial width, midpoint, and volume of the organs versus the patient age or BMI. Slight, positive linear trends were found for organ midpoint versus patient weight (max r{sup 2} = 0.382, mean r{sup 2} = 0.236). Similar trends were found for organ midpoint versus height (max r{sup 2} = 0.439, mean r{sup 2} = 0.200) and for organ volume versus height (max r{sup 2} = 0.410, mean r{sup 2} = 0.153). Gaussian fits performed on probability density functions of the adult organs resulted in r{sup 2}-values ranging from 0.96 to 0.996. The pediatric patients showed much stronger correlations overall. Strong correlations were observed between organ axial midpoint versus age, height, and weight (max r{sup 2} = 0.842, mean r{sup 2} = 0.790; max r{sup 2} = 0.949, mean r{sup 2} = 0.894; and max r{sup 2} = 0.870, mean r{sup 2} = 0.847, respectively). Moderate linear correlations were also observed for organ axial width

  3. Children's (Pediatric) CT (Computed Tomography)

    Medline Plus

    Full Text Available ... Site Index A-Z Children's (Pediatric) CT (Computed Tomography) Pediatric computed tomography (CT) is a fast, painless exam that uses ... of Children's CT? What is Children's CT? Computed tomography, more commonly known as a CT or CAT ...

  4. Investigation on centrifugal impeller in an axial-radial combined compressor with inlet distortion

    Science.gov (United States)

    Li, Du; Yang, Ce; Zhao, Ben; Zhou, Mi; Qi, Mingxu; Zhang, Jizhong

    2011-12-01

    Assembling an axial rotor and a stator at centrifugal compressor upstream to build an axial-radial combined compressor could achieve high pressure ratio and efficiency by appropriate size augment. Then upstream potential flow and wake effect appear at centrifugal impeller inlet. In this paper, the axial-radial compressor is unsteadily simulated by three-dimensional Reynolds averaged Navier-Stokes equations with uniform and circumferential distorted total pressure inlet condition to investigate upstream effect on radial rotor. The results show that span-wise nonuniform total pressure distribution is generated and radial and circumferential combined distortion is formed at centrifugal rotor inlet. The upstream stator wake deflects to rotor rotation direction and decreases with blade span increases. Circumferential distortion causes different separated flow formations at different pitch positions. The tip leakage vortex is suppressed in centrifugal blade passages. Under distorted inlet condition, flow direction of centrifugal impeller leading edge upstream varies evidently near hub and shroud but varies slightly at mid-span. In addition, compressor stage inlet distortion produces remarkable effect on blade loading of centrifugal blade both along chordwise and pitchwise.

  5. Uniform versus Nonuniform Axial Power Distribution in Rod Bundle CHF Experiments

    Directory of Open Access Journals (Sweden)

    Baowen Yang

    2014-01-01

    Full Text Available Rod bundle experiments with axially uniform and nonuniform heat fluxes are examined to explore the potential limitations of using uniform rod bundle CHF data for CHF correlation development of light water reactors with nonuniform axial power distribution (APD. The case of upstream burnout is presented as an example of unique phenomena associated with nonuniform rod bundle CHF experiments. It is a result from combined effect of axial nonuniform power shape and different interchannel mixing mechanisms. In addition, several key parameters are investigated with respect to their potential impacts on the thermal-hydraulic behaviors between rod bundles with uniform and nonuniform APDs. This type of misrepresentation cannot be amended or compensated through the use of correction factors due to the lack of critical information in the uniform rod bundle CHF testing as well as the fundamental difference in the underlining driving mechanisms. Other potential issues involved with the use of uniform rod bundle CHF data for nonuniform APD system applications also present strong evidence concerning the limitations and inadequacy of using uniform rod bundle CHF data for the correlation, prediction, and design limit calculation for safety analysis.

  6. Celebral computerized tomography

    International Nuclear Information System (INIS)

    Indications for cerebral computerized tomography (CT) and the diagnostic results from this examination are evaluated in 127 children. Pathological changes were found in 31 children, mostly based on such indications as increasing head size, suspicion of brain tumor, cerebral paresis, delayed psychomotor development and epileptic seizures. A list of indications for CT in children is given

  7. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Head What is CT Scanning of the Head? What are some ...

  8. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Safety En Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Computed Tomography ( ... used in your exam. You should inform your physician of all medications you are taking and if ...

  9. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available ... Safety En Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Computed Tomography ( ... used in your exam. You should inform your physician of all medications you are taking and if ...

  10. What is Computed Tomography?

    Science.gov (United States)

    ... word "tomography" is from the Greek word "tomos" meaning "slice" or "section" and "graphe" meaning "drawing." A CT imaging system produces cross-sectional ... The patient may receive an injection of a "contrast material" to facilitate visualization of vascular structure. Detectors ...

  11. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Head ... CT exam to be stressful. The technologist or nurse, under the direction of a physician, may offer ...

  12. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available ... Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Sinuses ... visibility of certain tissues or blood vessels. A nurse or technologist will insert an intravenous (IV) line ...

  13. Modulated Luminescent Tomography

    OpenAIRE

    Stefanov, Plamen; Cong, Wenxiang; Wang, Ge

    2014-01-01

    We propose and analyze a mathematical model of Modulated Luminescent Tomography. We show that when single X-rays or focused X-rays are used as an excitation, the problem is similar to the inversion of weighted X-ray transforms. In particular, we give an explicit inversion in the case of Dual Cone X-ray excitation.

  14. Positron emission tomography

    International Nuclear Information System (INIS)

    The aim of this project is to provide a simple summary of new trends in positron emission tomography and its basic physical principles. It provides thereby compendious introduction of the trends of the present development in diagnostics using PET systems. A review of available literature was performed. (author)

  15. Waste inspection tomography (WIT)

    International Nuclear Information System (INIS)

    The WIT program will provide an inspection system that offers the nuclear waste evaluator a unique combination of tools for regulatory-driven characterization of low-level waste (LLW), transuranic waste (TRU), and mixed waste drums. WIT provides nondestructive, noninvasive, and environmentally safe inspections using X-ray and gamma ray technologies, with reasonable cost and throughput. Two emission imaging techniques will be employed for characterizing materials in waste containers. The first of these is gamma emission tomography, commonly called single-photon emission computed tomography (SPECT). Rather than using an external radiation source, SPECT uses the emission of radioactive materials within the object of interest for imaging. In this case, emission from actual nuclear waste within a container will provide a three-dimensional image of the radioactive substances in the container. The second emission technique will use high-purity germanium detectors for gamma ray spectroscopy. This technique, called nondestructive assay (NDA), can identify the emitting isotopic species and strength. Work in emission tomography and assay of nuclear waste has been undertaken at Lawrence Livermore National Laboratory using a technique called Passive Tomography. Results from a process development unit are presented

  16. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available ... Computed tomography (CT) of the sinuses uses special x-ray equipment to evaluate the paranasal sinus cavities – hollow, ... is a diagnostic medical test that, like traditional x-rays, produces multiple images or pictures of the inside ...

  17. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Computed tomography (CT) of the head uses special x-ray equipment to help assess head injuries, severe headaches, ... is a diagnostic medical test that, like traditional x-rays, produces multiple images or pictures of the inside ...

  18. Dental Optical Coherence Tomography

    OpenAIRE

    Kun-Feng Lin; Jui-che Tsai; Ching-Cheng Chuang; Shyh-Yuan Lee; Yi-Ching Ho; Yao-Sheng Hsieh; Chia-Wei Sun

    2013-01-01

    This review paper describes the applications of dental optical coherence tomography (OCT) in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

  19. Holography and tomography

    Energy Technology Data Exchange (ETDEWEB)

    Howells, M. [Lawrence Berkeley National Lab., CA (United States)

    1997-02-01

    This session includes a collection of outlines of pertinent information, diagrams, graphs, electron micrographs, and color photographs pertaining to historical aspects and recent advances in the development of X-ray Gabor Holography. Many of the photographs feature or pertain to instrumentation used in holography, tomography, and cryo-holography.

  20. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina;

    2014-01-01

    Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described as the...

  1. Evaluation of the middle and inner ear structures: comparison of hybrid rendering, virtual endoscopy and axial 2D source images

    International Nuclear Information System (INIS)

    Recent developments in 3D reconstructions can enhance the quality and diagnostic value of axial 2D image data sets with direct benefits for clinical practice. To show the possible advantages of a hybrid rendering method [color-coded 3D shaded-surface display (SSD)- and volume rendering method] with the possibility of virtual endoscopy we have specifically highlighted the use in relation to the middle and inner ear structures. We examined 12 patients with both normal findings and postoperative changes, using image data sets from high-resolution spiral computed tomography (HRSCT). The middle and inner ear was segmented using an interactive threshold interval density volume-growing method and visualized with a color-coded SSD rendering method. The temporal bone was visualized using a transparent volume rendering method. The 3D- and virtual reconstructions were compared with the axial 2D source images. The evaluated middle and inner ear structures could be seen in their complete form and correct topographical relationship, and the 3D- and virtual reconstructions indicated an improved representation and spatial orientation of these structures. A hybrid and virtual endoscopic method could add information and improve the value of imaging in the diagnosis and management of patients with middle or inner ear diseases making the understanding and interpretation of axial 2D CT image data sets easier. The introduction of an improved rendering algorithm aids radiological diagnostics, medical education, surgical planning, surgical training, and postoperative assessment. (orig.)

  2. Numerical analysis of cocurrent conical and cylindrical axial cyclone separators

    Science.gov (United States)

    Nor, M. A. M.; Al-Kayiem, H. H.; Lemma, T. A.

    2015-12-01

    Axial concurrent liquid-liquid separator is seen as an alternative unit to the traditional tangential counter current cyclone due to lower droplet break ups, turbulence and pressure drop. This paper presents the numerical analysis of a new conical axial cocurrent design along with a comparison to the cylindrical axial cocurrent type. The simulation was carried out using CFD technique in ANSYS-FLUENT software. The simulation results were validated by comparison with experimental data from literature, and mesh independency and quality were performed. The analysis indicates that the conical version achieves better separation performance compared to the cylindrical type. Simulation results indicate tangential velocity with 8% higher and axial velocity with 80% lower recirculation compared to the cylindrical type. Also, the flow visualization counters shows smaller recirculation region relative to the cylindrical unit. The proposed conical design seems more efficient and suits the crude/water separation in O&G industry.

  3. Energy Dissipation in Sandwich Structures During Axial Compression

    DEFF Research Database (Denmark)

    Urban, Jesper

    2002-01-01

    The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full......-scale structural elements in fast sandwich vessels. Two of the crushing tests are simulated with the explicit finite element software LS-DYNA3D. The key results are load-end shortening relationship and the energy dissipation. Good agreement between the numerical predictions and the experiments are obtained. A...... simple analytical model for the energy dissipation during axial crushing is proposed. Keywords: Sandwich, Energy Dissipation, Axial Crushing, LS-DYNA, Analytical crushing models, Crashworthiness....

  4. CT of posterior ocular staphyloma in axial myopia

    International Nuclear Information System (INIS)

    We present two cases of posterior ocular staphylomas in axial myopia. CT findings of an enlarged globe with focal posterior bulging and scleraluveal rim thinning appear to be specific for this diagnosis. (orig.)

  5. Effect of axial heat flux distribution on CHF

    International Nuclear Information System (INIS)

    Previous investigations for the effect of axial heat flux distributions on CHF and the prediction methods are reviewed and summarized. A total of 856 CHF data in a tube with a non-uniform axial heat flux distribution has been compiled from the articles and analyzed using the 1995 Groeneveld look-up table. The results showed that two representative correction factors, K5 of the look-up table and Tongs F factor, can be applied to describe the axial heat flux distribution effect on CHF. However, they overpredict slightly the measured CHF, depending on the quality and flux peak shape. Hence, a corrected K5 factor, which accounts for the axial heat flux distribution effect is suggested to correct these trends. It predicted the CHF power for the compiled data with an average error of 1.5% and a standard deviation of 10.3%, and also provides a reasonable prediction of CHF locations

  6. CT of posterior ocular staphyloma in axial myopia

    Energy Technology Data Exchange (ETDEWEB)

    Swayne, L.C.; Garfinkle, W.B.; Bennett, R.H.

    1984-05-01

    We present two cases of posterior ocular staphylomas in axial myopia. CT findings of an enlarged globe with focal posterior bulging and scleraluveal rim thinning appear to be specific for this diagnosis.

  7. Evolving "Diagnostic" Criteria for Axial Spondyloarthritis in the Context of Anterior Uveitis.

    Science.gov (United States)

    Rosenbaum, James T

    2016-08-01

    Anterior uveitis is far more common than intermediate, posterior or panuveitis. About 50% of patients with acute anterior uveitis are HLA B27+. Those who are HLA B27+ are highly likely to have associated back, joint, or tendon disease. The majority of patients with acute anterior uveitis and inflammatory low back pain are suffering from axial spondyloarthritis and radiographic evidence for abnormal sacroiliac joints is not required to make this diagnosis. Received 12 October 2015; revised 31 January 2016; accepted 16 February 2016; published online 12 April 2016. PMID:27070270

  8. Physical activity in axial spondyloarthritis-tails from bench to bedside.

    Science.gov (United States)

    Gensler, Lianne S

    2016-06-01

    Physical therapy and exercise (recreational activity) are the cornerstones of non-pharmacologic therapy in axial spondyloarthritis (AxSpA) [1, 2]. These are components of physical activity, though physical activity is made up of activities beyond these and also include occupational activity. Not all activities in AxSpA appear to derive the same benefit for patients. In fact, it might be that while some activities are extremely beneficial for disease activity, function, and other outcomes, other activities may be harmful for the disease. The following review will examine animal model-based evidence and epidemiologic studies on physical activity in AxSpA. PMID:27118200

  9. The development of an axial active magnetic bearing / R. Gouws

    OpenAIRE

    Gouws, Rupert

    2004-01-01

    In this dissertation, the author presents the operation and development of active magnetic bearings (AMBs) , with specific focus on axial M s . The project objective is the development of an axial AMB system. The electromagnetic design, inductive sensor design, dSpace controller model design and actuating amplifier design are aspects discussed in this dissertation. The physical model constitutes two electromagnets positioned above and beneath a 2 kg steel disc with an air gap o...

  10. Design and Simulation of Axial Flow Maglev Blood Pump

    OpenAIRE

    Huachun Wu; Ziyan Wang; Xujun Lv

    2011-01-01

    The axial flow maglev blood pump (AFMBP) has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element an...

  11. Radial breathing mode of carbon nanotubes subjected to axial pressure

    OpenAIRE

    Lei, Xiao-Wen; Ni, Qing-Qing; Shi, Jin-Xing; Natsuki, Toshiaki

    2011-01-01

    In this paper, a theoretical analysis of the radial breathing mode (RBM) of carbon nanotubes (CNTs) subjected to axial pressure is presented based on an elastic continuum model. Single-walled carbon nanotubes (SWCNTs) are described as an individual elastic shell and double-walled carbon nanotubes (DWCNTs) are considered to be two shells coupled through the van der Waals force. The effects of axial pressure, wave numbers and nanotube diameter on the RBM frequency are investigated in detail. Th...

  12. Nuclear Axial Currents in Chiral Effective Field Theory

    OpenAIRE

    Baroni, A.; Girlanda, L.; Pastore, S.; Schiavilla, R.; Viviani, M

    2015-01-01

    Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory, and accounts for cancellations between the contributions of irreducible diagrams and the contributions due to non-static corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and...

  13. Watson's theorem and the $N\\Delta(1232)$ axial transition

    CERN Document Server

    Alvarez-Ruso, L; Nieves, J; Vacas, M J Vicente

    2016-01-01

    We present a new determination of the $N\\Delta$ axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez et al., Phys. Rev. D76, 033005 (2007) is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger $C_5^A(0)$, in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.

  14. Volume Dependence of the Axial Charge of the Nucleon

    OpenAIRE

    Hall, N. L.; Thomas, A. W.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia); Zanotti, J. M.

    2012-01-01

    It is shown that the strong volume-dependence of the axial charge of the nucleon seen in lattice QCD calculations can be understood quantitatively in terms of the pion-induced interactions between neighbouring nucleons. The associated wave function renormalization leads to an increased suppression of the axial charge as the strength of the interaction increases, either because of a decrease in lattice size or in pion mass.

  15. Passive axial stabilization of a magnetic radial bearing by superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Marinescu, M.; Marinescu, N. (Ing.-Buro f. Magnettechnik, Mailander Str.19, D-6000 Frankfurt/M. 70 (DE)); Tenbrink, J.; Krauth, H. (Vacuumschmelze GmbH, Gruner Weg 37, D-6450 Hanau (DE))

    1989-09-01

    Contactless bearings for high-speed operation can be constructed using passive magnet systems, which inherently need a second, active bearing for their stabilization. Completely passive bearings only can be obtained using diamagnetic materials. This study deals with the axial stabilization of magnetic radial bearings using a permanent magnet/superconductor system. Using finite element calculation procedures it is shown that axial forces of up 3000 N and stiffnesses of up to 400 N/mm may be achieved.

  16. Organo-Axial Volvulus of the Stomach with Diaphragmatic Eventration

    OpenAIRE

    Lee, June Sung; Park, Jae Wan; Sohn, Jang Won; Kim, Kyung Chul; Hwang, Seong Gyu; Park, Pil Won; Rim, Kyu Sung; Kim, Hee Jin

    2000-01-01

    Gastric volvulus occurs when the stomach rotates about its longitudinal axis (organo-axial volvulus), or about an axis joining the lesser and greater curvatures (mesentero-axial volvulus). Primary gastric volvulus, making up one third of cases, occurs when the stabilizing ligaments are too lax as a result of congenital or acquired causes. Secondary gastric volvulus, making up the remainder of cases, occurs in association with a paraesophageal hernia or other congenital or acquired diaphragmat...

  17. Particle simulation of an improved axially extracted vircator

    International Nuclear Information System (INIS)

    An axially extracted virtual cathode oscillator (vircator) with a feedback annulus is proposed and configured through particle-in-cell (PIC) simulation. In this paper, the effects of the feedback mechanism are studied through PIC method. The simulated results indicate that the improved new vircator can increase the output power twice large than that of the axially-extracted conventional vircator under the same condition. On the other hand, it can narrow the bandwidth and purify the modes

  18. Particle Simulation of an Improved Axially Extracted Vircator

    Institute of Scientific and Technical Information of China (English)

    刘振祥; 舒挺; 张建德; 钱宝良

    2003-01-01

    An axially extracted virtual cathode oscillator (vircator) with a feedback annulusis proposed and configured through particle-in-cell (PIC) simulation in Ref. [1]. In this paper,the effects of the feedback mechanism are studied through PIC method. The simulated resultsindicate that the improved new vircator can increase the output power twice large than that ofthe axially-extracted conventional vircator under the same condition. On the other hand, it cannarrow the bandwidth and purify the modes.

  19. Axial Non-linear Dynamic Soil-Pile Interaction - Keynote

    OpenAIRE

    Holeyman A.; Whenham V.

    2014-01-01

    This keynote lecture describes recent analytical and numerical advances in the modeling of the axial nonlinear dynamic interaction between a single pile and its embedding soil. On one hand, analytical solutions are developed for assessing the nonlinear axial dynamic response of the shaft of a pile subjected to dynamic loads, and in particular to vibratory loads. Radial inhomogeneity arising from shear modulus degradation is evaluated over a range of parameters and compared with those obtained...

  20. The New Performance Calculation Method of Fouled Axial Flow Compressor

    OpenAIRE

    Huadong Yang; Hong Xu

    2014-01-01

    Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section in...

  1. Axial Myopia and its Influence on Diabetic Retinopathy

    International Nuclear Information System (INIS)

    Objective: To evaluate the correlation between axial myopia and diabetic retinopathy. Study Design: Cross-sectional study. Place and Duration of Study: Eye Department of Postgraduate Medical Institute, Lahore General Hospital, from August 2012 to February 2013. Methodology: A total of 258 participants suffering from type-2 diabetic retinopathy were included. Axial length was measured by two optometrists using contact type ultrasound biometer. Colored retinal photographs, red free retinal photographs and Fundus Fluorescein Angiography (FFA) were performed on all patients using standard fundus camera. All fundus photographs and angiograms were independently reviewed and graded by two qualified vitreoretinal fellows. Results: Out of 258 patients, 163 were males (63.2%) and 95 (36.8%) were females. Average age of patients was 56.30 +- 7.57 years. Average axial length of right and left eyes were 23.16 mm and 23.15 mm respectively. There was statistically significant negative correlation between axial length and severity of diabetic retinopathy in the right eye, (Spearman correlation = -0.511, p = 0.0001) as well as the left eye (Spearman correlation = -0.522, p = 0.0001). Conclusion: There is a protective influence of longer axial length of globe on the stage and severity of diabetic retinopathy. This study may help in modifying the screening protocol for diabetic retinopathy amongst patients of differing axial lengths. (author)

  2. Difference between measured and predicted axial offset at NPP Krsko

    International Nuclear Information System (INIS)

    At NPP Krsko axial power distribution is monitored through periodic measurements of the AO (axial offset). AO represents the normalized power difference between top and bottom of the core. Within the core design process predicted values of axial offset (P-AO) for the entire core lifetime are calculated. During the core performance surveillance measured AO (M-AO) is compared to the predicted value. Measured vs. predicted axial offset difference (D-AO) of +3% at hot-full-power (HFP) steady-state core conditions is considered to be within measurement and design tolerances. During the last two 18 months cycles increase in the D-AO above 3 % was experienced for limited period of time at NPP Krsko - in cycle 22 for more than 90 EFPD (Effective Full Power Days). For such deviation evaluation has to be performed to confirm that reload safety evaluation and analysis of the core has not been impacted. Root cause analysis was performed afterwards and it was classified as a core design computer code deficiency. Precisely, inadequate axial actinides treatment in the computer code contributed to the observed axial offset difference. (author)

  3. Superfluid phase stability of 3He in axially anisotropic aerogel

    International Nuclear Information System (INIS)

    Measurements of superfluid 3He in 98% aerogel demonstrate the existence of a metastable A-like phase and a stable B-like phase. It has been suggested that the relative stability of these two phases is controlled by anisotropic quasiparticle scattering in the aerogel. Anisotropic scattering produced by axial compression of the aerogel has been predicted to stabilize the axial state of superfluid 3He. To explore this possibility, we used transverse acoustic impedance to map out the phase diagram of superfluid 3He in a ∼ 98% porous silica aerogel subjected to 17% axial compression. We have previously shown that axial anisotropy in aerogel leads to optical birefringence and that optical cross-polarization studies can be used to characterize such anisotropy. Consequently, we have performed optical cross-polarization experiments to verify the presence and uniformity of the axial anisotropy in our aerogel sample. We find that uniform axial anisotropy introduced by 17% compression does not stabilize the A-like phase. We also find an increase in the supercooling of the A-like phase at lower pressure, indicating a modification to B-like phase nucleation in globally anisotropic aerogels.

  4. Ultrasonic reflection tomography vs. canonical body approximation: experimental assessment of an infinite elastic cylindrical tube

    OpenAIRE

    Lasaygues, Philippe; Le Marrec, Loïc

    2008-01-01

    Comparisons were made between the results obtained using two quantitative ultrasound imaging methods on the solid cross section of a cylindrical tube that is infinite in the axial direction. The first method tested was the classical reflection tomography method based on the first-order Born approximation, which can only be used under conditions to obtain limited reconstruction of the external bound aries of the high contrast scatterer. The results were compared with those obtained using anoth...

  5. Direct coronal computed tomography of the lumbar spine: A new technical approach in supine position

    International Nuclear Information System (INIS)

    Computed tomography (CT) was carried out on 46 subjects with L5-S1 disk hernia. All the patients had a L5-S1 angle equal or greater than 40 degrees. Coronal sections of the disk were obtained with a rostral angulation of the gantry, having placed the lumbar spin in a hyperlordotic position. Results are discussed and compared with those obtained from para-axial transverse sections and multidirectional reformated images. (orig.)

  6. Direct coronal computed tomography of the lumbar spine: A new technical approach in supine position

    Energy Technology Data Exchange (ETDEWEB)

    Schnyder, P.; Uske, A.; Mansouri, B.

    1986-11-01

    Computed tomography (CT) was carried out on 46 subjects with L5-S1 disk hernia. All the patients had a L5-S1 angle equal or greater than 40 degrees. Coronal sections of the disk were obtained with a rostral angulation of the gantry, having placed the lumbar spin in a hyperlordotic position. Results are discussed and compared with those obtained from para-axial transverse sections and multidirectional reformated images.

  7. Diagnosis Of Lateral Sinus Thrombosis With Computed Tomography, Magnetic Resonance Imaging And Mr Angiography

    OpenAIRE

    KOYUNCU, M.; ŞEŞEN, T.; TANYERİ, Y.; Ünal, R.; TEKAT, A.; ÇELEBİ, M.; İNCESU, L.

    2010-01-01

    Three cases of lateral sinus thrombosis with chronic mastoiditis in children are presented. The findings of contrast enhanced computed tomography, Tl weighted axial magnetic resonance imaging, magnetic resonance angiography and neck ultrasonography were consisted with the diagnosis of lateral sinus thrombosis. Complete and modified radical mastoidectomies were underwent to the patients as connection with the extent of disease. The internal jugular vein was ligated in one case. Lateral sinus t...

  8. Neutron tomography for void distribution measurements

    International Nuclear Information System (INIS)

    Neutron tomography has previously been performed using large, stationary neutron sources such as reactors and spallation sources for applications where the object under study can be transported to the source. This paper accounts for the challenges met when applying neutron tomography using a portable accelerator driven neutron generator, which is required when studying non-transportable objects. In general, portable sources offer significantly lower neutron yields than stationary sources, implying the need for either longer measurement times or highly efficient measurement and/or analysis procedures. The particular application investigated here is the mapping of steam distributions in water (void distribution), which is of high importance for the performance of nuclear fuel assemblies in boiling water reactors (BWR). The void distribution cannot be measured directly in a reactor core, so instead various electrically-heated thermal-hydraulic test loops are used. In these loops, void correlations can be determined in full-size fuel assembly models, such as FRIGG in Sweden and DESIRE in Holland, but measurements are also performed in smaller, less complicated geometries. Previously, gamma tomography has been used to measure the void distribution in the FRIGG loop. However, improved capabilities to map the void distribution can be expected using neutrons because of their higher sensitivity to water relative to metal structures, as compared to gamma rays. At the same time, neutrons as probe also give rise to some challenges, such as high background from scattering. This paper investigates the possibility to use neutron tomography at axially symmetric objects such as the HWAT test loop in Sweden, where an annular two-phase flow of water/void is confined and heated by a steel cylinder. Monte Carlo simulations of the HWAT geometry and a suggested measurement setup have been carried out, using the particle transport code MCNPX. A reconstruction technique which exploits the

  9. Simultaneous measurement of cerebral blood flow and oxygen extraction fraction by positron emission tomography: theoretical study and experimental evidence of cerebral blood flow measurement with the C15O2 continuous inhalation technique

    International Nuclear Information System (INIS)

    The method of the continuous inhalation technique of oxygen-15 labelled CO2 coupled with positron emission tomography for the measurement of cerebral blood flow (C.B.F.) is described. An indirect experimental verification that this technique allowed the measurement of C.B.F. has been carried out in baboons by showing the expected change in the measured parameter with variations in the PaCO2. A critical investigation of the C15O2 model was performed. The amount of tracer present in the cerebral vascular pool has a negligible effect on C.B.F. value. The use of a mean brain-blood partition coefficient of water instead of that specific to gray or to white matter is commented upon, and its influence on the final C.B.F. value is studied. Lastly, the problem of the limited diffusion of water across the blood-brain-barrier is discussed. The study of the combined effects of gray-white mixing and limited wates extraction of the C.B.F. value shows that the C15O2 technique tends to understimate real C.B.F., and that this error is more severe with high flows and even gray white mixing. These limitations do not depart from the possibility to estimate in the same brain locus not only C.B.F. but oxygen utilization as well by the consecutive inhalation of C15O2 and 15O2. The advantages of this possibility has already been shown in a number of clinical studies

  10. EDITORIAL: Industrial Process Tomography

    Science.gov (United States)

    West, Robert M.

    2004-07-01

    Industrial process tomography remains a multidisciplinary field with considerable interest for many varied participants. Indeed this adds greatly to its appeal. It is a pleasure and a privilege to once again act as guest editor for a special feature issue of Measurement Science and Technology on industrial process tomography, the last being in December 2002. Those involved in the subject appreciate the efforts of Measurement Science and Technology in producing another issue and I thank the journal on their behalf. It can be seen that there are considerable differences in the composition of material covered in this issue compared with previous publications. The dominance of electrical impedance and electrical capacitance techniques is reduced and there is increased emphasis on general utility of tomographic methods. This is encompassed in the papers of Hoyle and Jia (visualization) and Dierick et al (Octopus). Electrical capacitance tomography has been a core modality for industrial applications. This issue includes new work in two very interesting aspects of image reconstruction: pattern matching (Takei and Saito) and simulated annealing (Ortiz-Aleman et al). It is important to take advantage of knowledge of the process such as the presence of only two components, and then to have robust reconstruction methods provided by pattern matching and by simulated annealing. Although crude reconstruction methods such as approximation by linear back projection were utilized for initial work on electrical impedance tomography, the techniques published here are much more advanced. The paper by Kim et al includes modelling of a two-component system permitting an adaption-related approach; the paper by Tossavainen et al models free surface boundaries to enable the estimation of shapes of objects within the target. There are clear improvements on the previous crude and blurred reconstructions where boundaries were merely inferred rather than estimated as in these new developments

  11. Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation.

    Science.gov (United States)

    Fuchs, Silvio; Rödel, Christian; Blinne, Alexander; Zastrau, Ulf; Wünsche, Martin; Hilbert, Vinzenz; Glaser, Leif; Viefhaus, Jens; Frumker, Eugene; Corkum, Paul; Förster, Eckhart; Paulus, Gerhard G

    2016-01-01

    Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1 μm, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence lengths corresponding to the spectral transmission windows of, e.g., silicon samples. The axial resolution of coherence tomography is thus improved from micrometers to a few nanometers. Tomographic imaging with an axial resolution better than 18 nm is demonstrated for layer-type nanostructures buried in a silicon substrate. Using wavelengths in the water transmission window, nanometer-scale layers of platinum are retrieved with a resolution better than 8 nm. XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window. PMID:26860894

  12. Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation

    Science.gov (United States)

    Fuchs, Silvio; Rödel, Christian; Blinne, Alexander; Zastrau, Ulf; Wünsche, Martin; Hilbert, Vinzenz; Glaser, Leif; Viefhaus, Jens; Frumker, Eugene; Corkum, Paul; Förster, Eckhart; Paulus, Gerhard G.

    2016-02-01

    Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1 μm, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence lengths corresponding to the spectral transmission windows of, e.g., silicon samples. The axial resolution of coherence tomography is thus improved from micrometers to a few nanometers. Tomographic imaging with an axial resolution better than 18 nm is demonstrated for layer-type nanostructures buried in a silicon substrate. Using wavelengths in the water transmission window, nanometer-scale layers of platinum are retrieved with a resolution better than 8 nm. XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window.

  13. Impact of iterative reconstruction on shape reproducibility of three-dimensional computed tomography

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate the effect of an iterative reconstruction method (IR) on shape reproducibility in three-dimensional (3D) computed tomography images. We used an IR (sinogram-affirmed iterative reconstruction: SAFIRE) implemented in a 64-channel multi slice computed tomography system (Siemens, SOMATOM Definition AS). We scanned a simulated vessel phantom with 180-Hounsfield unit (HU) vessel contrast at various radiation doses and reconstructed axial images of filtered back projection (FBP) and SAFIRE. Then we reconstructed multi-planar reconstruction (MPR) and volume rendering (VR) images from the axial images. Roundness was evaluated from MPR images and vessel surface roughness was evaluated from pixel value profiles of a vessel in VR images and visual evaluation by radiological technologists. In comparison on equivalent dose, the roundness and roughness were improved with increase of SAFIRE strength level. However, in comparison on equivalent noise (standard deviation: SD) of axial images, SAFIRE strength levels of 2 to 5 were significantly inferior to FBP (p<0.05). SAFIRE strength of 1 with a dose reduction of 19% maintained the shape reproducibility in all evaluations. Therefore, it would be not appropriate to use the SD of axial image as index for the dose reduction rate determination of 3D-CT images. (author)

  14. Determination of Axial Length Requiring Adjustment of Measured Circumpapillary Retinal Nerve Fiber Layer Thickness for Ocular Magnification

    Science.gov (United States)

    Hirasawa, Kazunori; Shoji, Nobuyuki; Yoshii, Yukako; Haraguchi, Shota

    2014-01-01

    Purpose To determine the axial length requiring adjustment of measured circumpapillary retinal nerve fiber layer (cpRNFL) thickness to account for ocular magnification during spectral-domain optical coherence tomography (SD-OCT). Methods In this prospective study, 148 eyes of 148 healthy student volunteers were imaged by two examiners using three-dimensional SD-OCT. In 54 randomly selected eyes, total cpRNFL thickness was measured with and without adjustment for ocular magnification to establish intra-examiner and inter-examiner measurement error. The 148 eyes were then divided into three groups according to the error values: control group (difference in the corrected and uncorrected total cpRNFL thickness was within the measurement error range), thinner group (the corrected total cpRNFL thickness was less than the uncorrected one), and thicker group (the corrected total cpRNFL thickness was more than the uncorrected one). The cutoff values of axial length between the control and the other groups were calculated by receiver operating characteristic analysis. Results Measurement error ranged from 4.2 to 5.3 µm; the threshold value was defined as 5.3 µm. The cutoff values of axial length between the thinner and the control groups and between the control and the thicker groups were 23.60 (area under the curve [AUC] = 0.959) and 25.55 (AUC = 0.944) mm, respectively. Conclusions Axial lengths shorter than 23.60 mm and longer than 25.55 mm require adjustment of measured cpRNFL thickness to account for ocular magnification during SD-OCT. Clinical Trial Registration UMIN Clinical Trials Registry (http://www.umin.ac.jp/) under unique trial number UMIN000013248 (date of registration: 02/24/2014) PMID:25215521

  15. Analysis of acetabular version in the native hip: comparison between 2D axial CT and 3D CT measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dandachli, Wael [Department of Orthopaedic Surgery, Imperial College London Hospitals, London (United Kingdom); Ul Islam, Saif; Tippett, Richard; Hall-Craggs, Margaret A.; Witt, Johan D. [University College London Hospitals, London (United Kingdom)

    2011-07-15

    To compare two-dimensional (2D) axial with three-dimensional (3D) computerized tomography (CT) measurements of acetabular version in native hips. CT scans of 34 hips in 17 consecutive patients being investigated for femoroacetabular impingement were analyzed. Acetabular version was measured using 2D CT at two different axial levels, one cranial (slice 2) and the other at the equator (slice 3). The measurements were repeated after correction for pelvic tilt. The results were compared to the measurements of anatomical version obtained using a 3D CT method that automatically corrects for pelvic tilt. The mean acetabular version using the 3D CT method was 15.7 (SD 6.9 ). The mean version using slice 2 was 9.3 (SD 6.5 ) before correction for pelvic tilt and 15.7 (SD 8.0 ) after the correction. The mean version using slice 3 was 16.4 (SD 4.2 ) before tilt correction and 19.0 (SD 5.0 ) after the correction. In relation to the 3D method, the intraclass correlation coefficient (ICC) was 0.58 for the uncorrected and 0.93 for the corrected slice 2 method. For the uncorrected and corrected slice 3 methods, the ICC was 0.64 and 0.89, respectively. The 2D axial methods produced variable results. The results that correlated best with the 3D method were those of the cranial slice (slice 2) after correction for pelvic tilt. Interpretation of 2D axial CT measurements of acetabular version should be done with caution. The level at which the measurement is done and the presence of pelvic tilt appear to be significant factors. (orig.)

  16. Investigation of axial power gradients near a control rod tip

    International Nuclear Information System (INIS)

    Highlights: → Pin power gradients near BWR control rod tips have been investigated. → A control rod tip is modeled in MCNP and compared to simplified 2D/3D geometry. → Small nodes increases pin power gradients; standard nodes underestimates gradients. → The MCNP results are validated against axial gamma scan of a controlled fuel pin. - Abstract: Control rod withdrawal in BWRs induces large power steps in the adjacent fuel assemblies. This paper investigates how well a 2D/3D method, e.g., CASMO5/SIMULATE5 computes axial pin power gradients adjacent to an asymmetrical control-rod tip in a BWR. The ability to predict pin power gradients accurately is important for safety considerations whereas large powers steps induced by control rod withdrawal can cause Pellet Cladding Interaction. The computation of axial pin power gradients axially around a control rod tip is a challenging task for any nodal code. On top of that, asymmetrical control rod handles are present in some BWR designs. The lattice code CASMO requires diagonal symmetry of all control rod parts. This introduces an error in computed pin power gradients that has been evaluated by Monte Carlo calculations. The results show that CASMO5/SIMULATE5, despite the asymmetrical control rod handle, is able to predict the axial pin power gradient within 1%/cm for axial nodal sizes of 15-3.68 cm. However, a nodal size of 3.68 cm still causes underestimations of pin power gradients compared with 1 cm nodes. Furthermore, if conventional node sizes are used, ∼15 cm, pin power gradients can be underestimated by over 50% compared with 1 cm nodes. The detailed axial pin power profiles from MCNP are corroborated by measured gamma scan data on fuel rods irradiated adjacent to control rods.

  17. Controllable tomography phase microscopy

    Science.gov (United States)

    Xiu, Peng; Zhou, Xin; Kuang, Cuifang; Xu, Yingke; Liu, Xu

    2015-03-01

    Tomography phase microscopy (TPM) is a new microscopic method that can quantitatively yield the volumetric 3D distribution of a sample's refractive index (RI), which is significant for cell biology research. In this paper, a controllable TPM system is introduced. In this system a circulatory phase-shifting method and piezoelectric ceramic are used which enable the TPM system to record the 3D RI distribution at a more controllable speed, from 1 to 40 fps, than in the other TPM systems reported. The resolution of the RI distribution obtained by this controllable TPM is much better than that in images recorded by phase contrast microscopy and interference tomography microscopy. The realization of controllable TPM not only allows for the application of TPM to the measurement of kinds of RI sample, but also contributes to academic and technological support for the practical use of TPM.

  18. Polarised light sheet tomography.

    Science.gov (United States)

    Reidt, Sascha L; O'Brien, Daniel J; Wood, Kenneth; MacDonald, Michael P

    2016-05-16

    The various benefits of light sheet microscopy have made it a widely used modality for capturing three-dimensional images. It is mostly used for fluorescence imaging, but recently another technique called light sheet tomography solely relying on scattering was presented. The method was successfully applied to imaging of plant roots in transparent soil, but is limited when it comes to more turbid samples. This study presents a polarised light sheet tomography system and its advantages when imaging in highly scattering turbid media. The experimental configuration is guided by Monte Carlo radiation transfer methods, which model the propagation of a polarised light sheet in the sample. Images of both reflecting and absorbing phantoms in a complex collagenous matrix were acquired, and the results for different polarisation configurations are compared. Focus scanning methods were then used to reduce noise and produce three-dimensional reconstructions of absorbing targets. PMID:27409945

  19. Neutron beam tomography software

    International Nuclear Information System (INIS)

    When a sample is traversed by a neutron beam, inhomogeneities in the sample will cause deflections, and the deflections will permit conclusions to be drawn concerning the location and size of the inhomogeneities. The associated computation is similar to problems in tomography, analogous to X-ray tomography though significantly different in detail. We do not have any point-sample information, but only mean values over short line segments. Since each mean value is derived from a separate neutron counter, the quantity of available data has to be modest; also, since each datum is an integral, its geometric precision is inferior to that of X-ray data. Our software is designed to cope with these difficulties. (orig.)

  20. Positron emission tomography.

    Science.gov (United States)

    Hoffman, E J; Phelps, M E

    1979-01-01

    Conventional nuclear imaging techniques utilizing lead collimation rely on radioactive tracers with little role in human physiology. The principles of imaging based on coincidence detection of the annihilation radiation produced in positron decay indicate that this mode of detection is uniquely suited for use in emission computed tomography. The only gamma-ray-emitting isotopes of carbon, nitrogen, and oxygen are positron emitters, which yield energies too high for conventional imaging techniques. Thus development of positron emitters in nuclear medicine imaging would make possible the use of a new class of physiologically active, positron-emitting radiopharmaceuticals. The application of these principles is described in the use of a physiologically active compound labeled with a positron emitter and positron-emission computed tomography to measure the local cerebral metabolic rate in humans. PMID:440173

  1. Mathematical Methods in Tomography

    CERN Document Server

    Louis, Alfred; Natterer, Frank

    1991-01-01

    The conference was devoted to the discussion of present and future techniques in medical imaging, including 3D x-ray CT, ultrasound and diffraction tomography, and biomagnetic ima- ging. The mathematical models, their theoretical aspects and the development of algorithms were treated. The proceedings contains surveys on reconstruction in inverse obstacle scat- tering, inversion in 3D, and constrained least squares pro- blems.Research papers include besides the mentioned imaging techniques presentations on image reconstruction in Hilbert spaces, singular value decompositions, 3D cone beam recon- struction, diffuse tomography, regularization of ill-posed problems, evaluation reconstruction algorithms and applica- tions in non-medical fields. Contents: Theoretical Aspects: J.Boman: Helgason' s support theorem for Radon transforms-a newproof and a generalization -P.Maass: Singular value de- compositions for Radon transforms- W.R.Madych: Image recon- struction in Hilbert space -R.G.Mukhometov: A problem of in- teg...

  2. Reinforced concrete tomography

    International Nuclear Information System (INIS)

    In this paper we describe the technique of reinforced concrete tomography, its historical background, recent technological developments and main applications. Gamma radiation sensitive plates are imprinted with radiation going through the concrete sample under study, and then processed to reveal the presence of reinforcement and defects in the material density. The three dimensional reconstruction, or tomography, of the reinforcement out of a single gammagraphy is an original development alternative to conventional methods. Re-bar diameters and positions may be determined with an accuracy of ± 1 mm 0.5-1 cm, respectively. The non-destructive character of this technique makes it particularly attractive in cases of inhabited buildings and diagnoses of balconies. (author)

  3. Construction and Biomechanical Properties of PolyAxial Self-Locking Anatomical Plate Based on the Geometry of Distal Tibia

    OpenAIRE

    Weiguo Liang; Weixiong Ye; Dongping Ye; Ziqiang Zhou; Zhiguang Chen; Aiguo Li; Zong-Han Xie; Lihai Zhang; Jiake Xu

    2014-01-01

    In order to provide scientific and empirical evidence for the clinical application of the polyaxial self-locking anatomical plate, 80 human tibias from healthy adults were scanned by spiral CT and their three-dimensional images were reconstructed using the surface shaded display (SSD) method. Firstly, based on the geometric data of distal tibia, a polyaxial self-locking anatomical plate for distal tibia was designed and constructed. Biomechanical tests were then performed by applying axial lo...

  4. An appraisal of golimumab in the treatment of severe, active nonradiographic axial spondyloarthritis

    Directory of Open Access Journals (Sweden)

    Paccou J

    2016-07-01

    Full Text Available Julien Paccou, René-Marc Flipo Department of Rheumatology, Lille University Hospital, Lille, France Abstract: Golimumab (Simponi® is a fully human tumor necrosis factor α inhibitor (TNFi antibody administered subcutaneously. In the European Union, golimumab is indicated for the treatment of adults with severe, active axial spondyloarthritis (axSpA, which includes both ankylosing spondylitis (AS and nonradiographic axSpA (nr-axSpA. In the US, it is indicated for the treatment of adults with active AS only. This article reviews the efficacy and tolerability of golimumab in nr-axSpA patients compared to other TNFi agents (adalimumab, infliximab, etanercept, and certolizumab pegol. In one ongoing, well-designed controlled study (GO-AHEAD, data at 16 weeks showed that treatment with golimumab (50 mg every 4 weeks was effective in improving the clinical signs and symptoms of disease in nr-axSpA patients. In addition, 16 weeks of treatment with golimumab reduced inflammation in the sacroiliac joints and spine in patients with nr-axSpA. Moreover, objective evidence of active inflammation at baseline, such as a positive magnetic resonance imaging scan and/or an elevated CRP level, was a good predictor of treatment response to golimumab. Golimumab was generally well tolerated in this study, with a tolerability profile consistent with that seen in previous clinical trials for other indications. Although additional long-term data are needed, current evidence indicates that golimumab is an effective option for the treatment of nr-axSpA. However, in the absence of comparative head-to-head trials, there is no recommended hierarchy for the first prescription of a TNFi agent for the treatment of either nr-axSpA or AS. Keywords: axial spondyloarthritis, nonradiographic axial spondyloarthritis, ankylosing spondylitis, golimumab, tumor necrosis factor α inhibitor, therapy

  5. Tutorial on photoacoustic tomography.

    Science.gov (United States)

    Zhou, Yong; Yao, Junjie; Wang, Lihong V

    2016-06-01

    Photoacoustic tomography (PAT) has become one of the fastest growing fields in biomedical optics. Unlike pure optical imaging, such as confocal microscopy and two-photon microscopy, PAT employs acoustic detection to image optical absorption contrast with high-resolution deep into scattering tissue. So far, PAT has been widely used for multiscale anatomical, functional, and molecular imaging of biological tissues. We focus on PAT’s basic principles, major implementations, imaging contrasts, and recent applications. PMID:27086868

  6. Positron-emission tomography

    International Nuclear Information System (INIS)

    Positron-emission tomography (PET) combines early biochemical assessment of pathology achieved by nuclear medicine with the precise localization achieved by computerized image reconstruction. In this technique a chemical compound with the desired biological activity is labeled with a radioactive isotope that decays by emitting a positron, or positive electron. With suitable interpretation PET images can provide a noninvasive, regional assessment of many biochemical processes that are essential to the functioning of the organ that is being visualized

  7. Reference structure tomography

    Science.gov (United States)

    Brady, David J.; Pitsianis, Nikos P.; Sun, Xiaobai

    2004-07-01

    Reference structure tomography (RST) uses multidimensional modulations to encode mappings between radiating objects and measurements. RST may be used to image source-density distributions, estimate source parameters, or classify sources. The RST paradigm permits scan-free multidimensional imaging, data-efficient and computation-efficient source analysis, and direct abstraction of physical features. We introduce the basic concepts of RST and illustrate the use of RST for multidimensional imaging based on a geometric radiation model.

  8. Compton tomography system

    Energy Technology Data Exchange (ETDEWEB)

    Grubsky, Victor; Romanoov, Volodymyr; Shoemaker, Keith; Patton, Edward Matthew; Jannson, Tomasz

    2016-02-02

    A Compton tomography system comprises an x-ray source configured to produce a planar x-ray beam. The beam irradiates a slice of an object to be imaged, producing Compton-scattered x-rays. The Compton-scattered x-rays are imaged by an x-ray camera. Translation of the object with respect to the source and camera or vice versa allows three-dimensional object imaging.

  9. Polychromatic diffraction contrast tomography

    Energy Technology Data Exchange (ETDEWEB)

    King, A., E-mail: king@synchrotron-soleil.fr [Synchrotron SOLEIL, Gif-sur-Yvette 91192 (France); Reischig, P. [Xnovo Technology ApS, 4600 Køge (Denmark); Department of Materials Science and Engineering, Delft University of Technology, Delft 2628 CD (Netherlands); Adrien, J. [MATEIS, INSA de Lyon, Villeurbanne 69621 (France); Peetermans, S. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Ludwig, W. [MATEIS, INSA de Lyon, Villeurbanne 69621 (France); European Synchrotron Radiation Facility, Grenoble 38043 (France)

    2014-11-15

    This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented.

  10. Polychromatic diffraction contrast tomography

    International Nuclear Information System (INIS)

    This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented

  11. Tomography with thermal neutrons

    International Nuclear Information System (INIS)

    This paper describes some tomographic measurements performed with thermal neutrons at the Instituto de Engenharia Nuclear - IEN/CNEN. The Argonauta Reactor at this Institute was used as neutron source. During the measurements this reactor produced a 36 x 105 n.cm-1.s-1 thermal neutron flux at end of the irradiation channel, wherein the tomographic system was installed. An homogeneous aluminum cylindrical rod was used to calibrate the system and to determine parameters governing the quality of the images. The aluminum cross section emerging from the image reconstruction process, was then compared with the values found in the literature. To evaluate the capability of this technique as a complementary tool, to the X-ray tomography, images of a solid aluminum cylinder, wherein, several thin rods of different materials were inserted, were taken. These materials were chosen among elements with high atomic numbers, as well as, among elements having a Z close to each other. A tomographic image of a small electric motor, displayed several elements of its internal structure. The overall results have demonstrated the capability of the thermal neutron tomography to complement the X-ray tomography, specially for samples containing elements of high atomic numbers such as lead (Z=82), or elements having atomic numbers close to each other such as iron (Z=26) and copper (Z=29). (author)

  12. An Axial Vector Photon in a Mirror World

    CERN Document Server

    Sharafiddinov, Rasulkhozha S

    2015-01-01

    The unity of symmetry laws emphasizes, in the case of a mirror CP-even Dirac Lagrangian, the ideas of the left- and right-handed axial-vector photons referring to long- and short-lived bosons of true neutrality, respectively. Such a difference in lifetimes expresses the unidenticality of masses, energies and momenta of axial-vector photons of the different components. They define the unified field theory equation of C-odd particles with an integral spin. Together with a new equation of a theory of truly neutral particles with the half-integral spin, the latter reflects the availability in their nature of the second type of the local axial-vector gauge transformation responsible for origination in the Lagrangian of C-oddity of an interaction Newton component giving an axial-vector mass to all the interacting particles and fields. The mirror axial-vector mass, energy and momentum operators constitute a CP-invariant equation of quantum mechanics, confirming that each of them can individually influence on matter ...

  13. Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in high-low labyrinth seals over a range of seal clearances and inlet swirl velocities. A well-established CFD-perturbation model was employed to predict the rotordynamic coefficients. A surprisingly large effect was detected for rotordynamic characteristics due to rotor shifting. It was also found that a less destabilizing effect arose from rotor axial shifting in the leakage flow direction, whereas a more destabilizing effect arose from shifting against the leakage flow direction. Further, a tentative explanation was proposed for the large sensitivities of dynamic forces to rotor axial shifting.

  14. Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting

    Directory of Open Access Journals (Sweden)

    David L. Rhode

    2006-03-01

    Full Text Available Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in high-low labyrinth seals over a range of seal clearances and inlet swirl velocities. A well-established CFD-perturbation model was employed to predict the rotordynamic coefficients. A surprisingly large effect was detected for rotordynamic characteristics due to rotor shifting. It was also found that a less destabilizing effect arose from rotor axial shifting in the leakage flow direction, whereas a more destabilizing effect arose from shifting against the leakage flow direction. Further, a tentative explanation was proposed for the large sensitivities of dynamic forces to rotor axial shifting.

  15. Artery Remodeling Under Axial Twist in Three Days Organ Culture.

    Science.gov (United States)

    Wang, Guo-Liang; Xiao, Yangming; Voorhees, Andrew; Qi, Ying-Xin; Jiang, Zong-Lai; Han, Hai-Chao

    2015-08-01

    Arteries often endure axial twist due to body movement and surgical procedures, but how arteries remodel under axial twist remains unclear. The objective of this study was to investigate early stage arterial wall remodeling under axial twist. Porcine carotid arteries were twisted axially and maintained for three days in ex vivo organ culture systems while the pressure and flow remained the same as untwisted controls. Cell proliferation, internal elastic lamina (IEL) fenestrae shape and size, endothelial cell (EC) morphology and orientation, as well as the expression of matrix metalloproteinases (MMPs), MMP-2 and MMP-9, and tissue inhibitor of metalloproteinase-2 (TIMP-2) were quantified using immunohistochemistry staining and immunoblotting. Our results demonstrated that cell proliferation in both the intima and media were significantly higher in the twisted arteries compared to the controls. The cell proliferation in the intima increased from 1.33 ± 0.21% to 7.63 ± 1.89%, and in the media from 1.93 ± 0.84% to 8.27 ± 2.92% (p culture, a decrease from the initial 15.58 ± 1.29 degrees. These results demonstrate that axial twist can stimulate artery remodeling. These findings complement our understanding of arterial wall remodeling under mechanical stress resulting from pressure and flow variations. PMID:25503524

  16. Method to measure tone of axial and proximal muscle.

    Science.gov (United States)

    Gurfinkel, Victor S; Cacciatore, Timothy W; Cordo, Paul J; Horak, Fay B

    2011-01-01

    The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention. PMID:22214974

  17. An Axial-Vector Photon in a Mirror World

    Science.gov (United States)

    Sharafiddinov, Rasulkhozha S.

    2016-03-01

    The unity of symmetry laws emphasizes, in the case of a mirror CP-even Dirac Lagrangian, the ideas of the left- and right-handed axial-vector photons referring to long- and short-lived bosons of true neutrality, respectively. Such a difference in lifetimes expresses the unidenticality of masses, energies and momenta of axial-vector photons of the different components. They define the unified field theory equation of C-odd particles with an integral spin. Together with a new equation of a theory of truly neutral particles with the half-integral spin, the latter reflects the availability in their nature of the second type of the local axial-vector gauge transformation responsible for origination in the Lagrangian of C-oddity of an interaction Newton component giving an axial-vector mass to all the interacting particles and fields. The mirror axial-vector mass, energy and momentum operators constitute a CP-invariant equation of quantum mechanics, confirming that each of them can individually influence on matter field. Thereby, findings suggest at the level of the mass-charge structure of gauge invariance a new equation for the C-noninvariant Lagrangian.

  18. Fluoroscopic lumbar interlaminar epidural injections in managing chronic lumbar axial or discogenic pain

    Directory of Open Access Journals (Sweden)

    Manchikanti L

    2012-08-01

    Full Text Available Laxmaiah Manchikanti,1,2 Kimberly A Cash,1 Carla D McManus,1 Vidyasagar Pampati,1 Ramsin Benyamin3,41Pain Management Center of Paducah, Paducah, KY; 2University of Louisville, Louisville, KY; 3Millennium Pain Center, Bloomington, IL; 4University of Illinois, Urbana-Champaign, IL, USAAbstract: Among the multiple causes of chronic low back pain, axial and discogenic pain are common. Various modalities of treatments are utilized in managing discogenic and axial low back pain including epidural injections. However, there is a paucity of evidence regarding the effectiveness, indications, and medical necessity of any treatment modality utilized for managing axial or discogenic pain, including epidural injections. In an interventional pain management practice in the US, a randomized, double-blind, active control trial was conducted. The objective was to assess the effectiveness of lumbar interlaminar epidural injections of local anesthetic with or without steroids for managing chronic low back pain of discogenic origin. However, disc herniation, radiculitis, facet joint pain, or sacroiliac joint pain were excluded. Two groups of patients were studied, with 60 patients in each group receiving either local anesthetic only or local anesthetic mixed with non-particulate betamethasone. Primary outcome measures included the pain relief-assessed by numeric rating scale of pain and functional status assessed by the, Oswestry Disability Index, Secondary outcome measurements included employment status, and opioid intake. Significant improvement or success was defined as at least a 50% decrease in pain and disability. Significant improvement was seen in 77% of the patients in Group I and 67% of the patients in Group II. In the successful groups (those with at least 3 weeks of relief with the first two procedures, the improvement was 84% in Group I and 71% in Group II. For those with chronic function-limiting low back pain refractory to conservative management

  19. Positron Emission Tomography Imaging of Pancreatic Cancer

    Directory of Open Access Journals (Sweden)

    Saravanan Kokila Krishnamoorthy

    2014-03-01

    Full Text Available Positron emission tomography (PET using 18F-fluorodeoxyglucose (FDG is increasingly used for the staging of solidmalignancies, including lung and esophagus. However, controversy still exists in relation to the application of PET inpancreatic cancer. The authors review seven studies (Abstracts #183, #189, #190, #254, #357, #375, #378 presented at the2014 ASCO Gastrointestinal Cancers Symposium and discuss on the role of PET in this disease. As the limitations of theResponse Evaluation Criteria In Solid Tumors (RECIST continue to become evident, FDG-PET may identify changes in themetabolic activity within pancreatic adenocarcinoma, and can provide both diagnostic and prognostic information.

  20. Cork quality estimation by using Compton tomography

    CERN Document Server

    Brunetti, A; Golosio, B; Luciano, P; Ruggero, A

    2002-01-01

    The quality control of cork stoppers is mandatory in order to guarantee the perfect conservation of the wine. Several techniques have been developed but until now the quality control was essentially related to the status of the external surface. Thus possible cracks or holes inside the stopper will be hidden. In this paper a new technique based on X-ray Compton tomography is described. It is a non-destructive technique that allows one to reconstruct and visualize the cross-section of the cork stopper analyzed, and so to put in evidence the presence of internal imperfections. Some results are reported and compared with visual classification.

  1. Finite quantum tomography via semidefinite programming

    OpenAIRE

    Jafarizadeh, M. A.; Mirzaee, M.; Rezaee, M

    2007-01-01

    Using the the convex semidefinite programming method and superoperator formalism we obtain the finite quantum tomography of some mixed quantum states such as: qudit tomography, N-qubit tomography, phase tomography and coherent spin state tomography, where that obtained results are in agreement with those of References \\cite{schack,Pegg,Barnett,Buzek,Weigert}.

  2. Evaluation of renal artery stenosis on CT-angiography: Comparison of various rendering techniques (AXIAL, MPR, MIP, SSD)

    International Nuclear Information System (INIS)

    Purpose: To evaluate the various reconstruction methods of helical-CT angiography for the assessment of hemodynamically relevant renal artery stenoses in comparison to i.a. DSA. Methods: In 76 renal arteries the reconstruction modalities AXIAL, MRP, MIP and SSD of helical-CT angiography were compared with the results of i.a. DSA for the determination of the grade and location of the stenosis. Results: The highest accuracy of stenosis grading was 76% with AXIAL reconstruction. In 8% of the cases grading of the stenosis was not evaluable by the AXIAL reconstruction. In these cases, a higher sensitivity in the detection of hemodynamically relevant stenoses (>grade II, >50%) was achieved with the reconstruction mode MPR (96%) than with MIP (92%). In 51% of the cases the reconstruction mode SSD was not suitable for any diagnosis of renal artery stenosis because of overlying calcified plaques. Conclusions: The evidence of hemodynamically relevant stenosis in helical-CT angiography in comparison to i.a. DSA succeeds most reliably by using the reconstruction modality AXIAL in combination with MRP. The MIP reconstruction provides information about the anatomy of the renal arteries within one image. (orig.)

  3. STED microscopy based on axially symmetric polarized vortex beams

    Science.gov (United States)

    Zhehai, Zhou; Lianqing, Zhu

    2016-03-01

    A stimulated emission depletion (STED) microscopy scheme using axially symmetric polarized vortex beams is proposed based on unique focusing properties of such kinds of beams. The concept of axially symmetric polarized vortex beams is first introduced, and the basic principle about the scheme is described. Simulation results for several typical beams are then shown, including radially polarized vortex beams, azimuthally polarized vortex beams, and high-order axially symmetric polarized vortex beams. The results indicate that sharper doughnut spots and thus higher resolutions can be achieved, showing more flexibility than previous schemes based on flexible modulation of both phase and polarization for incident beams. Project supported by the National Natural Science Foundation of China (Grant Nos. 61108047 and 61475021), the Natural Science Foundation of Beijing, China (Grant No. 4152015), the Program for New Century Excellent Talents in Universities of China (Grant No. NCET-13-0667), and the Top Young Talents Support Program of Beijing, China (Grant No. CIT&TCD201404113).

  4. Identification du comportement de composites en fatigue bi-axiale

    OpenAIRE

    Busca, Damien

    2014-01-01

    La connaissance du comportement de composites sous un état de contraintes multi-axial reste un enjeu majeur pour l’optimisation du dimensionnement des structures. La machine de fatigue bi-axiale présente au LGP permet de générer un état de contrainte bi-axial par l’utilisation d’éprouvettes cruciformes. La conception des éprouvettes reste un enjeu majeur pour les chercheurs pour répondre aux problèmes spécifiques liés aux matériaux composites. Un nouveau type d’éprouvette cruciforme en compos...

  5. Liquid Axial Mixing in Packed Tower at Elevated Pressure

    Institute of Scientific and Technical Information of China (English)

    唐忠利; 张鹏; 等

    2003-01-01

    Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m,in which the structured packing,Mellapak 350Y,was installed.Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa.The model parameters of Bo andθwere estimated with the least square method in the time domain.As liquid flow rate was increased,the liquid axial mixing decreased.under our experimental conditions,the effect of pressure on Bo number on single liquid phase was negligible,and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.

  6. Axial Shock in a Cylindrical Plasma with Current

    International Nuclear Information System (INIS)

    Hugoniot relations of a two-dimensional axial shock with current and magnetic field in a cylindrical shock tube were investigated by a numerical method. The radial profiles of the magnetic field, electric current, pressures, flow velocities and temperatures between the up- and down-stream radial force-balanced plasma of the shock were revealed by numerical analysis. It is clearly found that the axial shock can lead to two effects: one is an inverse skin effect (i.e., the current density rises towards the center of the conductor), the another is a reversed current effect which occurs near the edge and about a half radius. It is also found that the radial gradient of pressure, density and temperature all become very large near the center due to the axial shock

  7. Ball Screw Actuator Including an Axial Soft Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)

    2016-01-01

    An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.

  8. Fast imaging of mean, axial and radial diffusion kurtosis

    DEFF Research Database (Denmark)

    Hansen, Brian; Shemesh, Noam; Jespersen, Sune Nørhøj

    2016-01-01

    benefit from more efficient acquisition and computational methods. To meet this demand, we recently developed a method capable of estimating mean kurtosis with only 13 diffusion weighted images. This approach was later shown to provide very accurate mean kurtosis estimates and to be more efficient in...... terms of contrast to noise per unit time. However, insofar, the computation of two other critical DKI parameters, radial and axial kurtosis, has required the estimation of all 22 variables parameterizing the full DKI signal expression. Here, we present two strategies for estimating all of DKI......'s principal parameters – mean kurtosis, radial kurtosis, and axial kurtosis – using only 19 diffusion weighted images, compared to the current state-of-the-art acquisitions typically requiring about 60 images. The first approach is based on axially symmetric diffusion and kurtosis tensors, presented here for...

  9. Modified approach for calculating axial vector vacuum susceptibility

    International Nuclear Information System (INIS)

    We generalize our previous work [Phys. Rev. C 72, 035202 (2005)] on the linear response theory of the dressed quark propagator in the presence of a constant external field to the case of a variable external field in order to make it applicable to a wider class of problems. Using the axial vector vacuum susceptibility as an illustration, we apply this general formalism to extract a new expression for the axial vector vacuum susceptibility in the quantum chromodynamical (QCD) sum rule two-point external field formula. The numerical values of the axial vector vacuum susceptibility are calculated within the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach. A comparison with the results of the previous approaches is given

  10. Numerical analysis of cavitation within slanted axial-flow pump

    Institute of Scientific and Technical Information of China (English)

    张睿; 陈红勋

    2013-01-01

    In this paper, the cavitating flow within a slanted axial-flow pump is numerically researched. The hydraulic and cavitation performance of the slanted axial-flow pump under different operation conditions are estimated. Compared with the experimental hydraulic performance curves, the numerical results show that the filter-based model is better than the standard k-e model to predict the parameters of hydraulic performance. In cavitation simulation, compared with the experimental results, the proposed numerical method has good predicting ability. Under different cavitation conditions, the internal cavitating flow fields within slanted axial-flow pump are investigated. Compared with flow visualization results, the major internal flow features can be effectively grasped. In order to explore the origin of the cavitation performance breakdown, the Boundary Vorticity Flux (BVF) is introduced to diagnose the cavitating flow fields. The analysis results indicate that the cavitation performance drop is relevant to the instability of cavitating flow on the blade suction surface.

  11. The small axial charge of the N(1535) resonance

    CERN Document Server

    an, C S

    2008-01-01

    There is a natural cancellation between the contributions of the $qqq$ and $qqqq\\bar q$ components to the axial charge of the N(1535) resonance. While the probability of the former is larger than that of the latter, its coefficient in the axial charge expression is exceptionally small. The magnitude of two of the corresponding coefficients of the $qqqq\\bar q$ components are in contrast large and have the opposite sign. This result provides a phenomenological illustration of the recent unquenched lattice calculation result that the axial charge of the N(1535) resonance is very small, if not vanishing \\cite{takah}. The result sets an upper limit on the magnitude of the probability of $qqqq\\bar q$ components as well.

  12. Optimum axial flow taper in a countercurrent gas centrifuge

    Energy Technology Data Exchange (ETDEWEB)

    Von Halle, E.

    1979-02-01

    The effect of an axially varying countercurrent circulation rate in a gas centrifuge on the efficiency factors, e/sub I/, the ideality efficiency, and e/sub C/, the circulation efficiency, is investigated and compared with the case in which the countercurrent circulation rate is constant throughout the centrifuge. The optimum variation of the centrifuge parameter m, which is a measure of the countercurrent circulation rate, as a function of axial position in the centrifuge is determined. It is shown that when the countercurrent circulation rate has its optimum value at every axial position in the centrifuge, the product of the efficiency factors, e/sub I/ x e/sub C/, can exceed 81 per cent, the nominal upper limit of the value of the product of the efficiency factors for a constant countercurrent circulation rate, and can be quite close to unity. This is illustrated by numerical examples based on a centrifuge previously described in the literature.

  13. Twenty axial level handling in the APOSTOL code

    International Nuclear Information System (INIS)

    In many high-resolution calculation it has been proved that, in assemblies beside the control rod the pin-wise linear heat rate is different from linear heat rate calculated by pin-wise diffusion codes using only ten axial level code. In the linear heat rate of these assemblies there is a positive peak beside the intermediate part of control rod, which is the connection between the absorber and the fuel. In the ten level calculation cases this peak is not observable because of the homogenisation of the levels. Therefore more detailed axial division has to be used for the calculations. In this paper it is presented the application of a twenty axial level division in the APOSTOL code. It is presented the geometry of the nodes and the calculation of the cross sections of the nodes. Furthermore, the twenty level handling in the APOSTOL code is described. The same calculation result in realistic cases are presented. (author)

  14. Electromagnetic and axial structures of Baryon ground and resonant states

    International Nuclear Information System (INIS)

    This thesis is devoted to the investigation of the electroweak structures of baryons. One performs a comprehensive study of the electromagnetic and axial form factors of baryon ground states with flavors 'up', 'down', and 'strange'; regarding baryon resonances the axial charges are investigated. The dynamics for the description of baryons is furnished by the relativistic constituent-quark model, of which three different variants are applied here. The calculations are performed in the framework of relativistic quantum mechanics, where the electromagnetic and axial current operators are constructed along a spectator model in the point-form.While the evaluations of the electroweak form factors are based on an already established formalism, one develops a generally valid formulation for the axial charges. Thereby it becomes possible to calculate these quantities for arbitrary baryon states and completely general interaction models.It turns out that relativistic constituent-quark models can describe in the framework of a Poincare-invariant formalism not only the electromagnetic but also the axial form factors, which are calculated here for the first time for all baryons. Globally, a good agreement with experiment is achieved up to momentum transfers of about 4 GeV/c. With regard to the particularly sensitive quantities, like the electric radii and magnetic moments, the constituent-quark model based on Goldstone-boson exchange yields the best results. In cases, where no experimental data exist, the predictions agree well with results from lattice quantum chromodynamics. The analogue is true for the axial charges of baryon ground and resonant states. Except for some special cases, their values are presented here for the first time comprehensively and consistently. (author)

  15. A three-dimensional nodal method with Channel-wise Intrinsic Axial Mesh Adaptation

    International Nuclear Information System (INIS)

    Highlights: • CIAMA solves axial heterogeneity without iterative node re-homogenization. • CIAMA can easily resolve the control rod cusping problem. • CIAMA result shows great potential for 3-D pin-by-pin calculation. - Abstract: In a conventional coarse mesh nodal method the more accurate treatment of intra-nodal axial heterogeneity requires iterative axial node re-homogenization using axial flux profiles either reconstructed from core-wise coarse mesh solution or obtained from channel-wise axial fine mesh calculation. In this paper a new nodal method formulation, using Channel-wise Intrinsic Axial Mesh Adaptation (CIAMA), is proposed to solve this problem in a more fundamental way. For a given transverse (radial) leakage, along each axial channel a rigorous sub-node heterogeneous calculation is performed with the explicit axial heterogeneity within each coarse axial node. However, the transverse leakage between the axial channels is still calculated on the basis of coarse axial nodes, using the axially averaged radial current in each coarse axial node. Since the coupling between the axial channels is through the coarse axial nodes, it is not necessary to match the boundaries of the axial sub-nodes of neighboring axial channels in order to incorporate the axial sub-node calculation as an intrinsic part of the whole core global calculation. Therefore in the CIAMA nodal method, each axial channel is allowed to have its own sub-nodes adapting to its own axial heterogeneity variation. The CIAMA method has been implemented in the commercial code EGRET, which is used to qualify CIAMA. Excellent results of modeling fuel grid and control rod movement are presented. Application of CIAMA to three-dimensional pin-by-pin core calculation is also discussed and demonstrated to work well

  16. Value of computed tomography for evaluating the sub glottis in laryngeal and hypopharyngeal squamous cell carcinoma

    International Nuclear Information System (INIS)

    Context And Objective: Sub glottic involvement in squamous cell carcinoma is a determining factor for contraindicating conservative partial surgery. The subglottis is easily identified by axial computed tomography sections. The present study aimed to evaluate the occurrence of false-negative and false-positive results, and the overall accuracy of staging by computed tomography, in order to detect the involvement of the subglottic laryngeal compartment, in cases of laryngeal and hypopharyngeal squamous cell carcinoma. Design And Setting: Retrospective, non-randomized study of patients treated at Hospital Heliopolis, Sao Paulo, Brazil. Methods: Computed tomography scans were performed on third-generation equipment with 5-mm slice thickness. Afterwards, all patients underwent surgical and anatomopathological examinations as the gold standard procedures. Results: Among 60 patients, 14 were diagnosed with subglottic extension by surgical and histopathological examination. There were three false-negative and no false-positive results from computed tomography scans. The sensitivity and negative predictive value were 100.0%. Accuracy was 95.0%, specificity was 93.5% and positive predictive value was 82.4%. Conclusions: Computed tomography could serve as a powerful auxiliary method for staging laryngeal and hypopharyngeal cancer. However, precautions should be taken in analyzing computed tomography scan data, because vegetating lesions may also be projected into the subglottic compartment, without real involvement of the subglottis, which may cause a false-positive result. (author)

  17. Value of computed tomography for evaluating the sub glottis in laryngeal and hypopharyngeal squamous cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Ricardo Pires de; Barros, Nestor de; Paes Junior, Ademar Jose de Oliveira; Tornin, Olger de Souza; Rapoport, Abrao; Cerri, Giovanni Guido [Hospital Heliopolis, Sao Paulo, SP (Brazil). Dept. de Cirurgia de Cabeca e Pescoco, Otorrinolaringologia e Imagem]. E-mail: ricapires@ig.com.br; olger1@uol.com.br

    2007-03-15

    Context And Objective: Sub glottic involvement in squamous cell carcinoma is a determining factor for contraindicating conservative partial surgery. The subglottis is easily identified by axial computed tomography sections. The present study aimed to evaluate the occurrence of false-negative and false-positive results, and the overall accuracy of staging by computed tomography, in order to detect the involvement of the subglottic laryngeal compartment, in cases of laryngeal and hypopharyngeal squamous cell carcinoma. Design And Setting: Retrospective, non-randomized study of patients treated at Hospital Heliopolis, Sao Paulo, Brazil. Methods: Computed tomography scans were performed on third-generation equipment with 5-mm slice thickness. Afterwards, all patients underwent surgical and anatomopathological examinations as the gold standard procedures. Results: Among 60 patients, 14 were diagnosed with subglottic extension by surgical and histopathological examination. There were three false-negative and no false-positive results from computed tomography scans. The sensitivity and negative predictive value were 100.0%. Accuracy was 95.0%, specificity was 93.5% and positive predictive value was 82.4%. Conclusions: Computed tomography could serve as a powerful auxiliary method for staging laryngeal and hypopharyngeal cancer. However, precautions should be taken in analyzing computed tomography scan data, because vegetating lesions may also be projected into the subglottic compartment, without real involvement of the subglottis, which may cause a false-positive result. (author)

  18. A simple approach to the ABJ axial anomaly

    International Nuclear Information System (INIS)

    A very simple semi-quantitative derivation of the Adler-Bell-Jackiw (ABJ) axial anomaly is given, based on an investigation of the absorptive part of the VVA triangle graph and dispersion relations. Essential ingredients of our discussion are: normal Ward identities for the absorptive part of the relevant diagram, dimensional analysis, unitarity, and energy-momentum conservation. An explanation of the physical origin of axial anomaly, proposed in some earlier treatments within such a dispersive framework, is critically examined. In particular, the interpretation of the ABJ anomaly as an analogy of the Lee-Nauenberg effect occurring in the massless limit of spinor electrodynamics is shown to be fallacious

  19. Axial-symmetrical domain structures in ferrite-garnet films

    International Nuclear Information System (INIS)

    Applying the improved technique of double ultrahigh-speed photography one studied occurrence and progress of domain structure upon magnetization of a small section of (BiLaTm)3(FeGa)5O12 ferrite-garnet film prior to saturation. The radial deformation affecting the specimen on the magnetized coil side was determined to break single-axis anisotropy resulting in occurrence of axial-oriented band domain structure inside the magnetized range. That structure period reduced with growth of the pulse field amplitude. Band axial-oriented domain structure is formed under the effect of the magnetostatic axisymmetric field

  20. Vector and axial currents in Wilson chiral perturbation theory

    International Nuclear Information System (INIS)

    We reconsider the construction of the vector and axial-vector currents in Wilson Chiral Perturbation Theory, the low-energy effective theory for lattice QCD with Wilson fermions. We discuss in detail the finite renormalization of the currents that has to be taken into account in order to properly match the currents. We explicitly show that imposing the chiral Ward identities on the currents does, in general, affect the axial-vector current at O(a). As an application of our results we compute the pion decay constant to one loop in the two-flavor theory. Our result differs from previously published ones.

  1. Instability of Meridional Axial System in f(R) Gravity

    CERN Document Server

    Sharif, M

    2015-01-01

    We analyze dynamical instability of non-static reflection axial stellar structure by taking into account generalized Euler's equation in metric $f(R)$ gravity. Such an equation is obtained by contracting Bianchi identities of usual anisotropic and effective stress-energy tensors, which after using radial perturbation technique gives modified collapse equation. In the realm of $R+\\epsilon R^n$ gravity model, we investigate instability constraints at Newtonian and post-Newtonian approximations. We find that instability of meridional axial self-gravitating system depends upon static profile of structure coefficients while $f(R)$ extra curvature terms induce stability to the evolving celestial body.

  2. The gravitational axial superfield and the formalism of differential geometry

    International Nuclear Information System (INIS)

    The formalism of differential geometry in the physical 4+4-dimensional superspace (SS) is developed on the basis of the simplest supergravity group of general transformations of the coordinates of the left and right chiral SS. In this formalism the only independent dynamical variable is the axial gravitational superfield (SF). All the geometrical objects - supertetrades, affinities, etc. - are expressed in terms of the axial gravitational SF. Analysis of the transformation properties of the spinor-coordinate derivatives has led to a natural definition of the local Lorentz group for SF. The simplest Lagrangian for pure supergravity is discussed

  3. Axial crack propagation and arrest in pressurized fuselage

    Science.gov (United States)

    Kosai, M.; Shimamoto, A.; Yu, C.-T.; Walker, S. I.; Kobayashi, A. S.; Tan, P.

    1994-01-01

    The crack arrest capability of a tear strap in a pressurized precracked fuselage was studied through instrumented axial rupture tests of small scale models of an idealized fuselage. Upon pressurization, rapid crack propagation initiated at an axial through crack along the stringer and immediately kinked due to the mixed modes 1 and 2 state caused by the one-sided opening of the crack flap. The diagonally running crack further turned at the tear straps. Dynamic finite element analysis of the rupturing cylinder showed that the crack kinked and also ran straight in the presence of a mixed mode state according to a modified two-parameter crack kinking criterion.

  4. Experimental investigation on ducted counter-rotating axial flow fans

    OpenAIRE

    Nouri, Hussain; Ravelet, Florent; Bakir, Farid; Sarraf, Christophe

    2011-01-01

    An experimental study on counter-rotating axial-flow fans was carried out. The fans of diameter D = 375 mm were designed using an inverse method. The counter-rotating fans operate in a ducted-flow configuration and the overall performances are measured in a normalized test bench. The rotation rate of each fan is independently controlled. The axial spacing between the fans can vary from 10 to 50 mm by steps of 10 mm. The results show that the efficiency is strongly increased compared to a conv...

  5. An effective theory for QCD with an axial chemical potential

    CERN Document Server

    Andrianov, Alexander A; Espriu, Domenec; Planells, Xumeu

    2013-01-01

    We consider the low energy realization of QCD in terms of meson fields when an axial chemical potential is present; a situation that may be relevant in heavy ion collisions. We shall demonstrate that the presence of an axial charge constitutes an explicit source of parity breaking. The eigenstates of strong interactions do not have a definite parity and interactions that would otherwise be forbidden compete with the familiar ones. In this work, we first focus on scalars and pseudoscalars that are described by a generalized linear sigma model; and next, we give some hints on how the Vector Meson Dominance model describes the vector sector.

  6. Infrared and terahertz radiation of a crystal at axial channeling

    International Nuclear Information System (INIS)

    Basic properties of radiation of a crystal lattice excited by an axial channeling particle are considered. It is shown that a coherent radiation of atoms occurs if the frequency of oscillations of the channeled particle comes to a resonance with the vibrational mode of the crystal. Spectral and angular distribution of radiation and its polarization are calculated. In case of a relativistic channeled particle, the radiation of atoms is generated into a narrow cone in the direction of a crystallographic axis along which the particle is channeling. The radiation of atoms exited at axial channelling has significant degree of circular polarization

  7. Buckling localization in a cylindrical panel under axial compression

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Needleman, A.

    2000-01-01

    Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile......, but where subsequently the load starts to increase again, it is found that near the local load minimum, the buckling pattern switches back to a periodic type of pattern. The inelastic material behavior of the panel is described in terms of J(2) corner theory, which avoids the sometimes unrealistically...

  8. Spectral analysis in thin tubes with axial heterogeneities

    KAUST Repository

    Ferreira, Rita

    2015-01-01

    In this paper, we present the 3D-1D asymptotic analysis of the Dirichlet spectral problem associated with an elliptic operator with axial periodic heterogeneities. We extend to the 3D-1D case previous 3D-2D results (see [10]) and we analyze the special case where the scale of thickness is much smaller than the scale of the heterogeneities and the planar coefficient has a unique global minimum in the periodic cell. These results are of great relevance in the comprehension of the wave propagation in nanowires showing axial heterogeneities (see [17]).

  9. Ambient Noise Tomography of the British Isles

    Science.gov (United States)

    Nicolson, H. J.; Curtis, A.; Baptie, B.

    2009-12-01

    In recent years, surface wave tomography using empirical Green’s functions computed via the ambient noise interferometry method has become an established approach to lithospheric imaging problems. To date, ambient noise tomography has been successfully applied to seismometer arrays in the United States, Australia, Iceland, China, South Africa, Europe and the Tibetan Plateau. The basis of the ambient seismic interferometry method is that, by cross-correlating noise data between two seismic stations and stacking over a long enough time period, one can approximate the Green’s Function that would have been recorded at one of the stations if the other had actually been a source. Consequently, one of the main advantages of ambient noise interferometry is that traditional seismic sources such as earthquakes or ballistics are not required; therefore it is ideal for application to seismically quiescent areas such as the British Isles. The British Isles are an archipelago located adjacent to the Eurasian continental shelf in a typically intra-plate setting, formed by a complex amalgamation of several terranes. These range from Laurentian north of the Highland Boundary fault to Avalonian south of the Iapetus Suture and evidence of the regions turbulent geological past can be inferred from its lithospheric structure. Previous studies of the structure of the British Isles considered relatively few seismic stations and/or were limited to using offshore shots, quarry blasts or teleseismic earthquakes as seismic energy sources. We have applied the ambient noise tomography method to noise data recorded on approximately 100 broadband and short period seismometers, including many new stations, in the British Isles and mainland Europe. This dense coverage of the British Isles allows us to image the crust and upper mantle velocity structure with a horizontal resolution in the region of 100km across the North Sea and 30km in the mainland United Kingdom. Here we present the first

  10. Resistive plate chambers in positron emission tomography

    Science.gov (United States)

    Crespo, Paulo; Blanco, Alberto; Couceiro, Miguel; Ferreira, Nuno C.; Lopes, Luís; Martins, Paulo; Ferreira Marques, Rui; Fonte, Paulo

    2013-07-01

    Resistive plate chambers (RPC) were originally deployed for high energy physics. Realizing how their properties match the needs of nuclear medicine, a LIP team proposed applying RPCs to both preclinical and clinical positron emission tomography (RPC-PET). We show a large-area RPC-PET simulated scanner covering an axial length of 2.4m —slightly superior to the height of the human body— allowing for whole-body, single-bed RPC-PET acquisitions. Simulations following NEMA (National Electrical Manufacturers Association, USA) protocols yield a system sensitivity at least one order of magnitude larger than present-day, commercial PET systems. Reconstruction of whole-body simulated data is feasible by using a dedicated, direct time-of-flight-based algorithm implemented onto an ordered subsets estimation maximization parallelized strategy. Whole-body RPC-PET patient images following the injection of only 2mCi of 18-fluorodesoxyglucose (FDG) are expected to be ready 7 minutes after the 6 minutes necessary for data acquisition. This compares to the 10-20mCi FDG presently injected for a PET scan, and to the uncomfortable 20-30minutes necessary for its data acquisition. In the preclinical field, two fully instrumented detector heads have been assembled aiming at a four-head-based, small-animal RPC-PET system. Images of a disk-shaped and a needle-like 22Na source show unprecedented sub-millimeter spatial resolution.

  11. Integrated diffuse optical tomography and photoacoustic tomography: phantom validations

    OpenAIRE

    Li, Xiaoqi; Xi, Lei; Jiang, Ruixin; Yao, Lei; Jiang, Huabei

    2011-01-01

    We designed, fabricated and tested a novel imaging system that fuses diffuse optical tomography (DOT) and photoacoustic tomography (PAT) in a single platform. This platform takes advantages of both DOT and PAT, and can potentially provide dual-modality two dimensional functional and cellular images of the breast quantitatively. Here we describe this integrated platform along with initial tissue phantom validations.

  12. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina;

    2014-01-01

    Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described as the...... optical analogue to ultrasound. The inherent safety of the technology allows for in vivo use of OCT in patients. The main strength of OCT is the depth resolution. In dermatology, most OCT research has turned on non-melanoma skin cancer (NMSC) and non-invasive monitoring of morphological changes in a...

  13. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Andersen, Peter E.

    2015-01-01

    Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. Mapping the local reflectivity, OCT visualizes the morphology of the sample, in real time or at video rate. In addition......-rate imaging is feasible, which has enabled optical microangiography, i.e., visualization of retinal and chorodial blood flow. Such label-free optical microangiography might be feasible as an adjunct modality to fluorescence-based angiography. In this review, the fundamental principles of OCT imaging and its...

  14. DIY Tomography sample holder

    Science.gov (United States)

    Lari, L.; Wright, I.; Boyes, E. D.

    2015-10-01

    A very simple tomography sample holder at minimal cost was developed in-house. The holder is based on a JEOL single tilt fast exchange sample holder where its exchangeable tip was modified to allow high angle degree tilt. The shape of the tip was designed to retain mechanical stability while minimising the lateral size of the tip. The sample can be mounted on as for a standard 3mm Cu grids as well as semi-circular grids from FIB sample preparation. Applications of the holder on different sample systems are shown.

  15. Quantitative Computed Tomography

    OpenAIRE

    Balda, Michael

    2011-01-01

    Computed Tomography (CT) is a wide-spread medical imaging modality. Traditional CT yields information on a patient's anatomy in form of slice images or volume data. Hounsfield Units (HU) are used to quantify the imaged tissue properties. Due to the polychromatic nature of X-rays in CT, the HU values for a specific tissue depend on its density and composition but also on CT system parameters and settings and the surrounding materials. The main objective of Quantitative CT (QCT) is measuring ch...

  16. Compressive Phase Contrast Tomography

    CERN Document Server

    Maia, F R N C; Marchesini, S; Padmore, H A; Parkinson, D Y; Pien, J; Schirotzek, A; Yang, C; 10.1117/12.861946

    2010-01-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. In- terference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher con- trast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  17. Positron emission tomography

    CERN Document Server

    Paans, A M J

    2006-01-01

    Positron Emission Tomography (PET) is a method for measuring biochemical and physiological processes in vivo in a quantitative way by using radiopharmaceuticals labelled with positron emitting radionuclides such as 11C, 13N, 15O and 18F and by measuring the annihilation radiation using a coincidence technique. This includes also the measurement of the pharmacokinetics of labelled drugs and the measurement of the effects of drugs on metabolism. Also deviations of normal metabolism can be measured and insight into biological processes responsible for diseases can be obtained. At present the combined PET/CT scanner is the most frequently used scanner for whole-body scanning in the field of oncology.

  18. Radial reflection diffraction tomography

    Science.gov (United States)

    Lehman, Sean K.

    2012-12-18

    A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

  19. Hyperspectral optical diffraction tomography

    CERN Document Server

    Jung, JaeHwang; Yoon, Jonghee; Park, YongKeun

    2015-01-01

    Here, we present a novel microscopic technique for measuring wavelength-dependent three-dimensional (3-D) distributions of the refractive indices (RIs) of microscopic samples in the visible wavelengths. Employing 3-D quantitative phase microscopy techniques with a wavelength-swept source, 3-D RI tomograms were obtained in the range of 450 - 700 nm with a spectral resolution of a few nanometers. The capability of the technique was demonstrated by measuring the hyperspectral 3-D RI tomograms of polystyrene beads, human red blood cells, and hepatocytes. The results demonstrate the potential for label-free molecular specific 3-D tomography of biological samples.

  20. Approaching electrical tomography

    Directory of Open Access Journals (Sweden)

    P. L. Cosentino

    2000-06-01

    Full Text Available A general approach to electrical tomography is here described, based on the distribution of the experimental data to the set of voxels in which the subsoil has been divided. This approach utilizes the sensitivity coefficients as factors of the convolution procedure to execute the back projection of the data, to obtain the 3D pictures of the subsoil. A subsequent probabilistic filtering technique is described to improve the pictures in view of sharp boundary models. Some models are finally presented, mostly regarding cubic buried anomalies as well as pipe-shaped and L-shaped anomalies.

  1. Stored Luminescence Computed Tomography

    CERN Document Server

    Cong, Wenxiang; Wang, Ge

    2013-01-01

    The phosphor nanoparticles made of doped semiconductors, pre-excited by well-collimated X-ray radiation, were recently reported for their light emission upon NIR light stimulation. The characteristics of X-ray energy storage and NIR stimulated emission is highly desirable to design targeting probes and improve molecular and cellular imaging. Here we propose stored luminescence computed tomography (SLCT), perform realistic numerical simulation, and demonstrate a much-improved spatial resolution in a preclinical research context. The future opportunities are also discussed along this direction.

  2. Compressive Phase Contrast Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-09-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  3. Computed tomography device

    International Nuclear Information System (INIS)

    A computed tomography device comprising a subtraction unit which obtains differential data strings representing the difference between each time-serial projection data string of a group of projection data strings corresponding to a prospective reconstruction image generated by projection data strings acquired by a data acquisition system, a convolution unit which convolves each time-serial projection data string of the group of projection data strings corresponding to the prospective reconstruction image, and a back-projection unit which back-projects the convolved data strings

  4. Multiple scattering tomography.

    Science.gov (United States)

    Modregger, Peter; Kagias, Matias; Peter, Silvia; Abis, Matteo; Guzenko, Vitaliy A; David, Christian; Stampanoni, Marco

    2014-07-11

    Multiple scattering represents a challenge for numerous modern tomographic imaging techniques. In this Letter, we derive an appropriate line integral that allows for the tomographic reconstruction of angular resolved scattering distributions, even in the presence of multiple scattering. The line integral is applicable to a wide range of imaging techniques utilizing various kinds of probes. Here, we use x-ray grating interferometry to experimentally validate the framework and to demonstrate additional structural sensitivity, which exemplifies the impact of multiple scattering tomography. PMID:25062159

  5. Extended Diffraction Tomography

    CERN Document Server

    Schlottmann, R B

    2009-01-01

    We present the development of extended diffraction tomography, a new approach to the solution of the linear seismic waveform inversion problem. This method has several appealing features, such as the use of arbitrary depth-dependent reference models and the decomposition of the full 2D or 3D inverse problem into a large number of independent 1D problems. This decomposition makes the method naturally highly parallelizable. Careful implementation yields significant robustness with respect to noise. Several synthetic examples are shown which characterize the benefits of our method and demonstrate the usefulness of choosing realistic 1D reference media.

  6. Positron Emission Tomography (PET)

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs

  7. Pion electroproduction, partially conserved axial-vector current, chiral Ward identities, and the axial form factor revisited

    International Nuclear Information System (INIS)

    We reinvestigate Adler's partially conserved axial-vector current relation in the presence of an external electromagnetic field within the framework of QCD coupled to external fields. We discuss pion electroproduction within a tree-level approximation to chiral perturbation theory and explicitly verify a chiral Ward identity referred to as the Adler-Gilman relation. We critically examine soft-momentum techniques and point out how inadmissable approximations may lead to results incompatible with chiral symmetry. As a result we confirm that threshold pion electroproduction is indeed a tool to obtain information on the axial form factor of the nucleon

  8. Compressed sensing electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Leary, Rowan, E-mail: rkl26@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Saghi, Zineb; Midgley, Paul A. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Holland, Daniel J. [Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA (United Kingdom)

    2013-08-15

    The recent mathematical concept of compressed sensing (CS) asserts that a small number of well-chosen measurements can suffice to reconstruct signals that are amenable to sparse or compressible representation. In addition to powerful theoretical results, the principles of CS are being exploited increasingly across a range of experiments to yield substantial performance gains relative to conventional approaches. In this work we describe the application of CS to electron tomography (ET) reconstruction and demonstrate the efficacy of CS–ET with several example studies. Artefacts present in conventional ET reconstructions such as streaking, blurring of object boundaries and elongation are markedly reduced, and robust reconstruction is shown to be possible from far fewer projections than are normally used. The CS–ET approach enables more reliable quantitative analysis of the reconstructions as well as novel 3D studies from extremely limited data. - Highlights: • Compressed sensing (CS) theory and its application to electron tomography (ET) is described. • The practical implementation of CS–ET is outlined and its efficacy demonstrated with examples. • High fidelity tomographic reconstruction is possible from a small number of images. • The CS–ET reconstructions can be more reliably segmented and analysed quantitatively. • CS–ET is applicable to different image content by choice of an appropriate sparsifying transform.

  9. Advances in neutron tomography

    Indian Academy of Sciences (India)

    W Treimer

    2008-11-01

    In the last decade neutron radiography (NR) and tomography (NCT) have experienced a number of improvements, due to the well-known properties of neutrons interacting with matter, i.e. the low attenuation by many materials, the strong attenuation by hydrogenous constituent in samples, the wavelength-dependent attenuation in the neighbourhood of Bragg edges and due to better 2D neutron detectors. So NR and NCT were improved by sophisticated techniques that are based on the attenuation of neutrons or on phase changes of the associated neutron waves if they pass through structured materials. Up to now the interaction of the neutron spin with magnetic fields in samples has not been applied to imaging techniques despite the fact that it was proposed many years ago. About ten years ago neutron depolarization as imaging signal for neutron radiography or tomography was demonstrated and in principle it works. Now one can present much improved test experiments using polarized neutrons for radiographic imaging. For this purpose the CONRAD instrument of the HMI was equipped with polarizing and analysing benders very similar to conventional scattering experiments using polarized neutrons. Magnetic fields in different coils and in samples (superconductors) at low temperatures could be visualized. In this lecture a summary about standard signals (attenuation) and the more `sophisticated' imaging signals as refraction, small angle scattering and polarized neutrons will be given.

  10. Waste inspection tomography (WIT)

    Energy Technology Data Exchange (ETDEWEB)

    Bernardi, R.T. [Bio-Imaging Research, Inc., Lincolnshire, IL (United States)

    1995-10-01

    Waste Inspection Tomography (WIT) provides mobile semi-trailer mounted nondestructive examination (NDE) and assay (NDA) for nuclear waste drum characterization. WIT uses various computed tomography (CT) methods for both NDE and NDA of nuclear waste drums. Low level waste (LLW), transuranic (TRU), and mixed radioactive waste can be inspected and characterized without opening the drums. With externally transmitted x-ray NDE techniques, WIT has the ability to identify high density waste materials like heavy metals, define drum contents in two- and three-dimensional space, quantify free liquid volumes through density and x-ray attenuation coefficient discrimination, and measure drum wall thickness. With waste emitting gamma-ray NDA techniques, WIT can locate gamma emitting radioactive sources in two- and three-dimensional space, identify gamma emitting, isotopic species, identify the external activity levels of emitting gamma-ray sources, correct for waste matrix attenuation, provide internal activity approximations, and provide the data needed for waste classification as LLW or TRU.

  11. Positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a method for quantitative imaging of regional physiological and biochemical parameters. Positron emitting radioactive isotopes can be produced by a cyclotron, eg. the biologically important carbon (11C), oxygen (15O), and nitrogen (13N) elements. With the tomographic principles of the PET scanner the quantitative distribution of the administered isotopes can be determined and images can be provided as well as dynamic information on blood flow, metabolism and receptor function. In neurology PET has been used for investigations on numerous physiological processes in the brain: circulation, metabolism and receptor studies. In Parkinson's disease PET studies have been able to localize the pathology specifically, and in early stroke PET technique can outline focal areas with living but non-functioning cells, and this could make it possible to intervene in this early state. With positron emission tomography a quantitative evaluation of myocardial blood flow, glucose and fatty acid metabolism can be made as well as combined assessments of blood flow and metabolism. Combined studies of blood flow and metabolism can determine whether myocardial segments with abnormal motility consist of necrotic or viable tissue, thereby delineating effects of revascularisation. In the future it will probably be possible to characterize the myocardial receptor status in different cardiac diseases. The PET technique is used in oncology for clinical as well as more basic research on tumor perfusion and metabolism. Further, tumor uptake of positron labelled cytotoxic drugs might predict the clinical benefit of treatment. (au) (19 refs.)

  12. Computed tomography of electronics

    Science.gov (United States)

    Bossi, Richard H.; Kruse, Robert J.; Knutson, Benjamin W.

    1989-12-01

    The application of Computed Tomography (CT) and laminography was tested on a variety of electronic components. The effort was performed as a preliminary testing task assignment in the Advanced Development of X ray Computed Tomography Application program. A key area for testing was printed circuit boards for the inspection of solder bonds and in particular for leadless chip carrier devices. During the course of the task assignment several other categories of electronic devices were examined including transformers, connectors, switches from solution and contrast sensitivity phantoms developed for the programs were used to establish quantitative measures of capability used to generate images. This preliminary testing of electronics lead to the conclusion that higher resolution CT scanning is needed to resolve details of interest. CT testing on commercially available system could resolve high contrast details in the range of 2 to 4 lp/mm; however, in many electronic components finer resolution is needed to detect microcracking, voiding and other features. Further testing on high resolution system is recommended. Two areas of immediate potential economic payback for electronics inspection were identified; the inspection of high volume printed circuit board production using high speed laminography and nondestructive failure analysis studies components using high-resolution CT.

  13. Auroral Tomography Workshop, Proceedings

    International Nuclear Information System (INIS)

    In ionospheric and atmospheric physics the importance of multi-station imaging has grown as a consequence of the availability of scientific grade CCD cameras with digital output and affordable massive computing power. Tomographic inversion techniques are used in many different areas, e.g. medicine, plasma research and space physics. The tomography workshop was announced to gather a limited group of people interested in auroral tomography or tomographic inversion methods in general. ALIS (Auroral Large Imaging System) is a multi-station ground-based system developed primarily for three-dimensional auroral imaging, however other non-auroral objects can be studied with ALIS, e.g. stratospheric clouds. Several of the contributions in the workshop dealt with problems related to geometries similar to the ALIS-configuration. The Proceedings contain written contributions received either in abstract form or as full papers. The Proceedings also contain contributions intended for the Workshop but not presented due to the absence of the speaker. Separate abstracts have been prepared for 15 of the 17 papers

  14. Elevated temperature axial and torsional fatigue behavior of Haynes 188

    Science.gov (United States)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1992-06-01

    The results of high-temperature axial and torsional low-cycle fatigue experiments performed on Haynes 188, a wrought cobalt-base superalloy, are reported. Fatigue tests were performed at 760 C in air on thin-walled tubular specimens at various ranges under strain control. Data are also presented for coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. The data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME boiler and pressure vessel code), Manson-Halford, Modified Multiaxiality Factor (proposed here), Modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The Modified Multiaxiality Factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.

  15. Improving axial depth of cut accuracy in micromilling

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2004-01-01

    and their rapid warming and cooling, which prevent the achievement of a steady state. Several other factors, independent on the tool-workpiece interaction, influence the machining accuracy. The cutting parameter most heavily affected is the axial depth of cut which is the most critical when using...

  16. Elevated temperature axial and torsional fatigue behavior of Haynes 188

    Science.gov (United States)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1995-01-01

    The results are reported for high-temperature axial and torsional low-cycle fatigue experiments performed at 760 C in air on thin-walled tubular specimens of Haynes 188, a wrought cobalt-based superalloy. Data are also presented for mean coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. This data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME Boiler and Pressure Code), Manson-Halford, modified multiaxiality factor (proposed in this paper), modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The modified multiaxiality factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.

  17. Axial heterogeneous core concept applied for super phoenix reactor

    International Nuclear Information System (INIS)

    Always maintaining the current design rules, this paper presents a parametric study on the type of axial heterogeneous core concept (CHA), utilizing a core of fast reactor Super Phenix type, reaching a maximum thermal burnup rate of 150000 M W d/t and being managed in single batch. (author)

  18. Defining active sacroiliitis on MRI for classification of axial spondyloarthritis

    DEFF Research Database (Denmark)

    Lambert, Robert G W; Bakker, Pauline A C; van der Heijde, Désirée;

    2016-01-01

    OBJECTIVES: To review and update the existing definition of a positive MRI for classification of axial spondyloarthritis (SpA). METHODS: The Assessment in SpondyloArthritis International Society (ASAS) MRI working group conducted a consensus exercise to review the definition of a positive MRI for...

  19. Dynamic calibration of tri-axial piezoelectric force transducers

    International Nuclear Information System (INIS)

    Applied dynamic loads are often difficult to measure accurately due to the dynamic response of the sensor used and the dependence of the sensor's sensitivity on the mounting and loading details. For tri-axial force transducers, which are capable of measuring forces along the axial direction and along both directions of the transducer's face, dynamic calibration is further complicated by the coupling of the sensor's measurement directions. For this reason, a new apparatus for dynamic calibration of normal and tangential directions of a tri-axial piezoelectric force transducer has been constructed and tested. The calibration force is provided from a spring loaded uni-axial impulse hammer. The apparatus allows for calibration at a variety of calibration angles and speeds; the loading for all cases of a nonzero calibration angle is oblique, with the point of force application being eccentric to the centerline of the force transducer's normal axis. As such, tangential loads are always accompanied by a normal load. The calibration results show that the normal direction correction factors have a systematic dependence on the calibration angle; the tangential correction factors show some scatter but do not appear to be dependent on the calibration angle

  20. AXIAL DEFFLECTION STUDIES OF RING SHAPED FORCE TRANSDUCER: A REVIEW

    Directory of Open Access Journals (Sweden)

    SUDHIR KUMAR,

    2011-01-01

    Full Text Available The ring shaped force transducers are widely used in practice and are available in varying capacities from few hundred newtons to mega newtons. The present paper discusses the deflection studies of thering shaped force transducers under action of axial forces. Various methods leading to the measurement of deflection have been discussed and compared here.

  1. On the axially symmetric equilibrium of a magnetically confined plasma

    International Nuclear Information System (INIS)

    The axially symmetric equilibrium of a magnetically confined plasma is reconsidered, with the special purpose of studying high-beta schemes with a purely poloidal magnetic field. A number of special solutions of the pressure and magnetic flux functions are shown to exist, the obtained results may form starting-points in a further analysis of physically relevant configurations. (Auth.)

  2. COMPARISON OF AXIAL FAN ROTOR EXPERIMENTAL DATA WITH CFD SIMULATION

    OpenAIRE

    Aleš Prachař

    2016-01-01

    Data obtained from an experimental simulation on a new test rig for axial fans are compared to a CFD simulation. The Edge solver is used and the development needed for the simulation (boundary conditions, free stream consistency) is described. Adequate agreement between the measured and calculated data is observed.

  3. COMPARISON OF AXIAL FAN ROTOR EXPERIMENTAL DATA WITH CFD SIMULATION

    Directory of Open Access Journals (Sweden)

    Aleš Prachař

    2016-02-01

    Full Text Available Data obtained from an experimental simulation on a new test rig for axial fans are compared to a CFD simulation. The Edge solver is used and the development needed for the simulation (boundary conditions, free stream consistency is described. Adequate agreement between the measured and calculated data is observed.

  4. A cylindrical drift chamber with azimuthal and axial position readout

    International Nuclear Information System (INIS)

    A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in π-p interactions. We describe the chamber's design considerations, details of its construction, electronics, and performance characteristics. (orig.)

  5. Modelling the cardiac transverse-axial tubular system

    Czech Academy of Sciences Publication Activity Database

    Pásek, Michal; Šimurda, J.; Christé, G.; Orchard, C.

    2008-01-01

    Roč. 96, - (2008), s. 226-246. ISSN 0079-6107 Institutional research plan: CEZ:AV0Z20760514 Keywords : cardiac cell * transverse-axial tubular system * quantitative modelling Subject RIV: BO - Biophysics Impact factor: 6.388, year: 2008

  6. On the Applications of Axial Representation of Trigonometric Functions

    Science.gov (United States)

    Siadat, M. Vali

    2006-01-01

    In terms of modern pedagogy, having visual interpretation of trigonometric functions is useful and quite helpful. This paper presents, pictorially, an easy approach to prove all single angle trigonometric identities on the axes. It also discusses the application of axial representation in calculus--finding the derivative of trigonometric functions.

  7. FINITE ELEMENT ANALYSIS OF AXIAL FEED BAR ROLLING

    Institute of Scientific and Technical Information of China (English)

    C.G. Xu; G.H. Liu; G.S. Ren; Z. Shen; C.P. Ma; W. W. Ren

    2007-01-01

    A flexible technique of hot working of bars by axial feed rolling was introduced. The processdeformation, strain field, stress field, and temperature field of the parts are analyzed by finite elementmethod (FEM)-simulation software DEFORM-3D. The material flow rule and tool load have beeninvestigated.

  8. View of the Axial Field Spectrometer (R807)

    CERN Multimedia

    1980-01-01

    In this view of the Axial Field Spectrometer at I8, the vertical uranium/scintillator hadron calorimeter (just left of centre) is retracted to give access to the cylindrical central drift chamber. The yellow iron structure served as a filter to identify muons, with MWPCs and the array of Cherenkov counters to the right.

  9. Axial and focal-plane diffraction catastrophe integrals

    Energy Technology Data Exchange (ETDEWEB)

    Berry, M V [H H Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Howls, C J [School of Mathematics, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

    2010-09-17

    Exact expressions in terms of Bessel functions are found for some of the diffraction catastrophe integrals that decorate caustics in optics and mechanics. These are the axial and focal-plane sections of the elliptic and hyperbolic umbilic diffraction catastrophes, and symmetric elliptic and hyperbolic unfoldings of the X{sub 9} diffraction catastrophes. These representations reveal unexpected relations between the integrals.

  10. On the generation techniques of axially symmetric stationary metrics

    Indian Academy of Sciences (India)

    S Chaudhuri

    2002-03-01

    In the present paper, a relationship between the method of Gutsunaev–Manko and the soliton technique (for two-soliton solutions) of Belinskii–Zakharov, for generating solutions of axially symmetric stationary space-times in general relativity is discussed.

  11. Etanercept for the treatment of non-radiographic axial spondyloarthritis.

    Science.gov (United States)

    Rios Rodriguez, Valeria; Poddubnyy, Denis

    2016-05-01

    Presently, tumor necrosis factor α antagonist therapy is the only effective alternative treatment to nonsteroidal anti-inflammatory drugs for the entire spectrum of axial spondyloarthritis, including non-radiographic and radiographic (=ankylosing spondylitis) forms. Recently, etanercept has been approved by the European Medicines Agency for the treatment of non-radiographic axial spondyloarthritis, increasing the number of available treatment options for this indication. The latest data on etanercept concerning clinical efficacy and safety in short-term and long-term treatment of patients with non-radiographic axial spondyloarthritis who do not respond to the first-line therapy with non-steroidal anti-inflammatory drugs suggests good efficacy and safety profiles similar to that observed previously in ankylosing spondylitis. This article reviews recent data on the efficacy and safety of etanercept and is focused on the treatment of non-radiographic axial spondyloarthritis. This article will also discuss the role of etanercept in the context of current and developing treatment options. PMID:26788837

  12. Computed Tomography Measuring Inside Machines

    Science.gov (United States)

    Wozniak, James F.; Scudder, Henry J.; Anders, Jeffrey E.

    1995-01-01

    Computed tomography applied to obtain approximate measurements of radial distances from centerline of turbopump to leading edges of diffuser vanes in turbopump. Use of computed tomography has significance beyond turbopump application: example of general concept of measuring internal dimensions of assembly of parts without having to perform time-consuming task of taking assembly apart and measuring internal parts on coordinate-measuring machine.

  13. Computed tomography of abdominal trauma

    International Nuclear Information System (INIS)

    Abdominal lesions following an accident or surgical interventions are becoming more frequently indications for investigations by computed tomography. Changes of spleen, liver, kidneys, pancreas, and of the retroperitoneal space are discussed. Advantages of computed tomography compared to other investigative methods are shown. (orig.)

  14. Fluid Chemistry Through an Eruption Cycle at Axial Seamount 1998-2011

    Science.gov (United States)

    Butterfield, D. A.; Chadwick, B.; Lilley, M. D.; Roe, K. K.; Lupton, J. E.; Dziak, R. P.; Walker, S. L.; Olson, E. J.; Evans, L. J.

    2011-12-01

    A primary goal for the NeMO seafloor observatory at Axial Seamount was to monitor and study a hydrothermal system through the cycle from one eruption to the next. With the January 1998 eruption and the April 2011 eruption discovered during Jason ROV operations in late July this year, that goal has now been accomplished. Based on observations and fluid temperature/chemistry measurements before and after both eruptions, there are common features leading up to and following the eruptions. Both eruptions at Axial originated in the SE corner of the caldera associated with the S Rift Zone. Isolated snowblower vents were found on new lava following both eruptions. Centimeter-thick orange hydrothermal mats formed rapidly on the new lava flows. There is some evidence that the fluids from ASHES vent field, located near the SW caldera wall, were hottest before the 1998 eruption. A second high-temperature vent field is located in the SE caldera just east of the recent lava flows. Lava flows came close to both high-temperature fields in 2011, but did not flow over any known chimneys. Recorded time series for several high-temperature vents show increasing temperatures from 2001 through 2010. Vent fluid chlorinity decreased at ASHES for 0.5 to 2 years following the 1998 eruption. As of 3.5 months after the 2011 eruption, ASHES fluid chlorinity did not change significantly. High gas contents reflect magma degassing throughout the entire history of fluid sampling at Axial. Spatial and temporal patterns of vent fluid chemistry will be presented.

  15. The Role of 18F-FDG-Positron Emission Tomography/Computed Tomography in Staging Primary Breast Cancer

    Directory of Open Access Journals (Sweden)

    Naoki Niikura, Naoto T. Ueno

    2010-01-01

    Full Text Available Despite Medicare approving the use of positron emission tomography/computed tomography (PET/CT in staging primary breast cancer, little evidence is available to support the use of 18F-FDG-PET/CT for the detection of distant metastases in the initial staging of breast cancer. In this review of the literature listed in MEDLINE, we examine whether 18F-FDG-PET/CT may play a role in the initial staging of breast cancer. We discuss studies comparing PET/CT with conventional imaging for diagnosing distant metastases and axillary and extra-axillary lymph node metastases.

  16. Computerised tomography of the orbits

    Directory of Open Access Journals (Sweden)

    Talwar Inder

    1988-01-01

    Full Text Available Computerised Tomography has revolutionised the approach to many problems, especially orbital diseases. It is a simple, safe, non-invasive diagnostic examination done on an out patient. Computerised Tomography not only shows the presence of a lesion but also shows the extent of the disease and its relationship to other intraorbital and adjacent structures. With coronal scans, relationship of orbital disease to the optic nerve and extraocular muscles can be well demonstrated. However it must be remembered that Computerised Tomography is not a microscope to give histopathological diagnosis but we can often draw a conclusion of the nature of the disease by Computerised′ Tomography appearances and clinical details. Now Computerised Tomography has become the primary investigation of choice in evaluating orbital disease.

  17. Axial SPN and radial MOC coupled whole core transport calculation

    International Nuclear Information System (INIS)

    The Simplified PN(SPN) method is applied to the axial solution of the two-dimensional (2-D) method of characteristics (MOC) solution based whole core transport calculation. A sub-plane scheme and the nodal expansion method (NEM) are employed for the solution of the one-dimensional (1-D) SPN equations involving a radial transverse leakage. The SPN solver replaces the axial diffusion solver of the DeCART direct whole core transport code to provide more accurate, transport theory based axial solutions. In the sub-plane scheme, the radial equivalent homogenization parameters generated by the local MOC for a thick plane are assigned to the multiple finer planes in the subsequent global three-dimensional (3-D) coarse mesh finite difference (CMFD) calculation in which the NEM is employed for the axial solution. The sub-plane scheme induces a much less nodal error while having little impact on the axial leakage representation of the radial MOC calculation. The performance of the sub-plane scheme and SPN nodal transport solver is examined by solving a set of demonstrative problems and the C5G7MOX 3-D extension benchmark problems. It is shown in the demonstrative problems that the nodal error reaching upto 1,400 pcm in a rodded case is reduced to 10 pcm by introducing 10 sub-planes per MOC plane and the transport error is reduced from about 150 pcm to 10 pcm by using SP3. Also it is observed, in the C5G7MOX rodded configuration B problem, that the eigenvalues and pin power errors of 180 pcm and 2.2% of the 10 sub-planes diffusion case are reduced to 40 pcm and 1.4%, respectively, for SP3 with only about a 15% increase in the computing time. It is shown that the SP5 case gives very similar results to the SP3 case. (author)

  18. Imaging of cerebellopontine angle lesions: an update. Part 2: intra-axial lesions, skull base lesions that may invade the CPA region, and non-enhancing extra-axial lesions

    Energy Technology Data Exchange (ETDEWEB)

    Bonneville, Fabrice; Chiras, Jacques [Pitie-Salpetriere Hospital, Department of Neuroradiology, Paris (France); Savatovsky, Julien [Adolphe de Rothschild Foundation, Department of Radiology, Paris (France)

    2007-11-15

    Computed tomography (CT) and magnetic resonance (MR) imaging reliably demonstrate typical features of vestibular schwannomas or meningiomas in the vast majority of mass lesions responsible for cerebellopontine angle (CPA) syndrome. However, a large variety of unusual lesions can also be encountered in the CPA. Covering the entire spectrum of lesions potentially found in the CPA, these articles explain the pertinent neuroimaging features that radiologists need to know to make clinically relevant diagnoses in these cases, including data from diffusion- and perfusion-weighted imaging or MR spectroscopy, when available. A diagnostic algorithm based on the lesion's site of origin, shape and margins, density, signal intensity and contrast material uptake is also proposed. Non-enhancing extra-axial CPA masses are cystic (epidermoid cyst, arachnoid cyst, neurenteric cyst) or contain fat (dermoid cyst, lipoma). Tumours can also extend into the CPA by extension from the skull base (paraganglioma, chondromatous tumours, chordoma, cholesterol granuloma, endolymphatic sac tumour). Finally, brain stem or ventricular tumours can present with a significant exophytic component in the CPA that may be difficult to differentiate from an extra-axial lesion (lymphoma, hemangioblastoma, choroid plexus papilloma, ependymoma, glioma, medulloblastoma, dysembryoplastic neuroepithelial tumour). (orig.)

  19. Two-dimensional nonlinear dynamics of an axially moving viscoelastic beam with time-dependent axial speed

    International Nuclear Information System (INIS)

    In the present study, the coupled nonlinear dynamics of an axially moving viscoelastic beam with time-dependent axial speed is investigated employing a numerical technique. The equations of motion for both the transverse and longitudinal motions are obtained using Newton’s second law of motion and the constitutive relations. A two-parameter rheological model of the Kelvin–Voigt energy dissipation mechanism is employed in the modelling of the viscoelastic beam material, in which the material time derivative is used in the viscoelastic constitutive relation. The Galerkin method is then applied to the coupled nonlinear equations, which are in the form of partial differential equations, resulting in a set of nonlinear ordinary differential equations (ODEs) with time-dependent coefficients due to the axial acceleration. A change of variables is then introduced to this set of ODEs to transform them into a set of first-order ordinary differential equations. A variable step-size modified Rosenbrock method is used to conduct direct time integration upon this new set of first-order nonlinear ODEs. The mean axial speed and the amplitude of the speed variations, which are taken as bifurcation parameters, are varied, resulting in the bifurcation diagrams of Poincaré maps of the system. The dynamical characteristics of the system are examined more precisely via plotting time histories, phase-plane portraits, Poincaré sections, and fast Fourier transforms (FFTs)

  20. Use of a coccygeal axial pattern flap for reconstruction following tumour excision in a cat.

    Science.gov (United States)

    Montinaro, Vincenzo; Massari, Federico; Romanelli, Giorgio

    2015-04-01

    A 6-year-old male castrated Chartreux cat was referred for recurrence of an injection site sarcoma at the base of the tail 7 months after the initial surgery. Upon presentation, the physical examination was unremarkable except for a non-painful, subcutaneous mass, 2 cm in diameter, firmly attached to the underlying tissue on the left lateral side of the tail base. Complete blood count, biochemistry and urinalysis were within normal limits; thoracic radiographs and abdominal ultrasound showed no evidence of metastatic disease. After removing the mass with 3 cm margins laterally and two deep fascial planes, the defect was reconstructed after tail amputation using a coccygeal axial pattern flap based on the lateral coccygeal arteries and veins. There were no complications with wound healing and the only visible change was a difference in hair coat direction at the 1 month re-check. This is the first report to describe the utility and feasibility of the coccygeal axial pattern flap to reconstruct a large cutaneous defect over the caudodorsal pelvic region in a cat. PMID:24899050

  1. An Intact Brachyury Function Is Necessary to Prevent Spurious Axial Development in Xenopus laevis

    Science.gov (United States)

    Aguirre, Cecilia E.; Murgan, Sabrina; Carrasco, Andrés E.; López, Silvia L.

    2013-01-01

    We have previously shown that the member of the HES family hairy2 induces the ectopic expression of dorsal markers when it is overexpressed in the ventral side of Xenopus embryos. Intriguingly, hairy2 represses the mesoderm transcription factor brachyury (bra) throughout its domain in the marginal zone. Here we show that in early gastrula, bra and hairy2 are expressed in complementary domains. Overexpression of bra repressed hairy2. Interference of bra function with a dominant-negative construct expanded the hairy2 domain and, like hairy2 overexpression, promoted ectopic expression of dorsal axial markers in the ventral side and induced secondary axes without head and notochord. Hairy2 depletion rescued the ectopic dorsal development induced by interference of bra function. We concluded that an intact bra function is necessary to exclude hairy2 expression from the non-organiser field, to impede the ectopic specification of dorsal axial fates and the appearance of incomplete secondary axes. This evidence supports a previously unrecognised role for bra in maintaining the dorsal fates inhibited in the ventral marginal zone, preventing the appearance of trunk duplications. PMID:23359630

  2. Optical Tomography in Combustion

    DEFF Research Database (Denmark)

    Evseev, Vadim

    The new methodology of optical infrared tomography of flames and hot gas flows was developed in the PhD project with a view to future industrial applications. In particular, the methodology for the tomographic reconstruction of an axisymmetric lab flame temperature profile was developed and tested...... in the lab using Fourier transform infrared spectroscopy techniques, including a new tomographic measurement scheme, sweeping scanning, having great potential for industrial applications with limited optical access. The results were compared to the reference point measurements on the same flame and...... infrared spectral measurements at several line-of-sights with a view to applications for tomographic measurements on full-scale industrial combustion systems. The system was successfully applied on industrial scale for simultaneous fast exhaust gas temperature measurements in the three optical ports of the...

  3. 4-D Photoacoustic Tomography

    Science.gov (United States)

    Xiang, Liangzhong; Wang, Bo; Ji, Lijun; Jiang, Huabei

    2013-01-01

    Photoacoustic tomography (PAT) offers three-dimensional (3D) structural and functional imaging of living biological tissue with label-free, optical absorption contrast. These attributes lend PAT imaging to a wide variety of applications in clinical medicine and preclinical research. Despite advances in live animal imaging with PAT, there is still a need for 3D imaging at centimeter depths in real-time. We report the development of four dimensional (4D) PAT, which integrates time resolutions with 3D spatial resolution, obtained using spherical arrays of ultrasonic detectors. The 4D PAT technique generates motion pictures of imaged tissue, enabling real time tracking of dynamic physiological and pathological processes at hundred micrometer-millisecond resolutions. The 4D PAT technique is used here to image needle-based drug delivery and pharmacokinetics. We also use this technique to monitor 1) fast hemodynamic changes during inter-ictal epileptic seizures and 2) temperature variations during tumor thermal therapy.

  4. Neurovascular photoacoustic tomography

    Directory of Open Access Journals (Sweden)

    Song Hu

    2010-06-01

    Full Text Available Neurovascular coupling refers to the relationship between neuronal activities and downstream hemodynamic responses. Photoacoustic tomography (PAT, enabling comprehensive label-free imaging of hemodynamic activities with highly scalable penetration and spatial resolution, has great potential in the study of neurovascular coupling. In this review, we first introduce the technical basis of hemodynamic PAT—including label-free quantification of total hemoglobin concentration, blood oxygenation, and blood flow—as well as its applications in hemodynamic monitoring. Then, we demonstrate the potential application of PAT in neurovascular imaging by highlighting representative studies on cerebral vascular responses to whisker stimulation and Alzheimer’s disease. Finally, potential research directions and associated technical challenges are discussed.

  5. Positon Emission Tomography sampling

    International Nuclear Information System (INIS)

    This work deals with the study of data acquisition in Positon Emission Tomography (PET). Its aim is to optimize the quantity of data measured compared with the maximum spatial resolution it is possible to reach on a reconstructed image. One of the contribution in this field is to determine the efficiency of rectangular detectors compared with the square ones. In the second part of this thesis is studied the performances of a PET scanner for the small animal imagery. The originality of this scanner is the use of liquid xenon as scintillating medium and the ability to measure the interaction depth. A Monte Carlo simulation chain of this scanner has been carried out, compared and validated with the experimental results. (O.M.)

  6. Atom Probe Tomography

    International Nuclear Information System (INIS)

    Atom probe tomography (APT) is a lens-less point-projection microscopy that resolves individual atoms on the surface of a sharply pointed tip (radius of curvature R < 100 nm), at a magnification of the order of ⁓106. The specimen tip is pulsed to a positive potential V with respect to ground, thereby generating electric fields E ⁓ V/R of some 10 V/nm. Ions released from the apex due to field evaporation are sent flying to a position sensitive detector where they are identified by time-of-flight mass spectrometry. Continuous removal of single atoms provides the possibility of a 3D elemental characterization of solids with sub-nm spatial resolution. The basic principles of the technique and some selected analytical applications will be discussed. (author)

  7. Computed tomography in neurocysticercosis

    International Nuclear Information System (INIS)

    Three hundred and fifty seven computed tomography (CT) from 100 different patients with neurocysticercosis (NC) were studied between 1979 and 1988. All patients were treated with praziquantel (PZQ). A new classification attempting to recognize the CT evolution profile in NC as well as assigning a possible link between CT findings and biological conditions of cysts is evaluated. It was possible to conclude that: intact cysts remain unchanged in consecutive CTs by 11 months and exhibit signs of degeneration in about 18 months after PZQ drug therapy; degenerating cysts can be detected by 10.5 months, disappear in 11 months and become nodular calcifications in about 25 months. Therefore, a time period of at least 36 months can be estimated for the complete evolution profile of cysts in the brain parenchyma. (author)

  8. Tomography by positrons emission

    International Nuclear Information System (INIS)

    The tomography by positrons emission is a technology that allows to measure the concentration of positrons emission in a tri dimensional body through external measurements. Among the isotope emissions have carbon isotopes are (11C), of the oxygen (15O), of the nitrogen (13N) that are three the element that constitute the base of the organic chemistry. Theses have on of the PET's most important advantages, since many biological interesting organic molecules can be tracer with these isotopes for the metabolism studies 'in vivo' through PET, without using organic tracers that modify the metabolism. The mentioned isotopes, also possess the characteristic of having short lifetime, that constitute on of PET's advantages from the dosimetric point of view. Among 11C, 15O, and 13N, other isotopes that can be obtained of a generator as the 68Ga and 82Rb

  9. Emission computed tomography

    International Nuclear Information System (INIS)

    Although there are many common aspects to x-ray transmission and radionuclide emission (ECT) computerized tomography, there are added difficulties and a number of particular factors which form the basis of ECT. The relationship between the physical factors, system design, methodologic approach and assumptions of ECT is discussed. The instrumentation design and application strategies in ECT at this time are diverse and in a rapid stage of development. The approaches are divided into two major categories of Single Photon Counting (SPC) employing scanner and camera concepts with radionuclides of 99/sup m/Tc, 201Tl, 123I etc., and Annihilation Coincidence Detection (ACD) of positron-emitting radionuclides. Six systems in the former and ten systems in the latter category, with examples of typical studies, illustrate the different approaches

  10. High-resolution spectrometer: solution to the axial resolution and ranging depth trade-off of SD-OCT

    Science.gov (United States)

    Marvdashti, Tahereh; Lee, Hee Yoon; Ellerbee, Audrey K.

    2013-03-01

    We demonstrate a cross-dispersed spectrometer for Spectral Domain Optical Coherence Tomography (SD-OCT). The resolution of a conventional SD-OCT spectrometer is limited by the available sizes of the linear array detectors. The adverse consequences of this finite resolution is a trade-off between achieving practical field of view (i.e. ranging depth) and maintaining high axial resolution. Inspired by spectrometer designs for astronomy, we take advantage of very high pixel-density 2D CCD arrays to map a single-shot 2D spectrum to an OCT A-scan. The basic system can be implemented using a high-resolution Echelle grating crossed with a prism in a direction orthogonal to the dispersion axis. In this geometry, the interferometric light returning from the OCT system is dispersed in two dimensions; the resulting spectrum can achieve more pixels than a traditional OCT spectrometer (which increases the ranging depth) and maintains impressive axial resolution because of the broad bandwidth of the detected OCT light. To the best of our knowledge, we present the first demonstration of OCT data using an Echelle-based cross-dispersed spectrometer. Potential applications for such a system include high-resolution imaging of the retina or the anterior segment of the eye over extended imaging depths and small animal imaging.

  11. Common approach for compensation of axial motion artifacts in swept-source OCT and dispersion in Fourier-domain OCT.

    Science.gov (United States)

    Hillmann, Dierck; Bonin, Tim; Lührs, Christian; Franke, Gesa; Hagen-Eggert, Martin; Koch, Peter; Hüttmann, Gereon

    2012-03-12

    Swept-source optical coherence tomography (SS-OCT) is sensitive to sample motion during the wavelength sweep, which leads to image blurring and image artifacts. In line-field and full-field SS-OCT parallelization is achieved by using a line or area detector, respectively. Thus, approximately 1000 lines or images at different wavenumbers are acquired. The sweep duration is identically with the acquisition time of a complete B-scan or volume, rendering parallel SS-OCT more sensitive to motion artifacts than scanning OCT. The effect of axial motion on the measured spectra is similar to the effect of non-balanced group velocity dispersion (GVD) in the interferometer arms. It causes the apparent optical path lengths in the sample arm to vary with the wavenumber. Here we propose the cross-correlation of sub-bandwidth reconstructions (CCSBR) as a new algorithm that is capable of detecting and correcting the artifacts induced by axial motion in line-field or full-field SS-OCT as well as GVD mismatch in any Fourier-domain OCT (FD-OCT) setup. By cross-correlating images which were reconstructed from a limited spectral range of the interference signal, a phase error is determined which is used to correct the spectral modulation prior to the calculation of the A-scans. Performance of the algorithm is demonstrated on in vivo full-field SS-OCT images of skin and scanning FD-OCT of skin and retina. PMID:22418560

  12. Mixing and axial dispersion in Taylor-Couette flow: experimental and numerical study

    International Nuclear Information System (INIS)

    Taylor-Couette flows between two concentric cylinders have great potential applications in chemical engineering. They are particularly convenient for two-phase small scale devices enabling solvent extraction operations. An experimental device was designed with this idea in mind. It consists of two concentric cylinders with the inner one rotating and the outer one fixed. Taylor-Couette flows take place in the annular gap between them, and are known to evolve towards turbulence through a sequence of successive instabilities. Macroscopic quantities, such as axial dispersion and mixing index, are extremely sensitive to these flow structures, which may lead to flawed modelling of the coupling between hydrodynamics and mass transfer. This particular point has been studied both experimentally and numerically. The flow and mixing have been characterized by means of flow visualization and simultaneous PIV (Particle Imaging Velocimetry) and PLIF (Planar Laser Induced Fluorescence) measurements. PLIF visualizations showed clear evidences of different transport mechanisms including 'intra-vortex mixing' and 'inter-vortex mixing'. Under WVF and MWVF regimes, intra-vortex mixing is controlled by chaotic advection, due to the 3D nature of the flow, while inter-vortex transport occurs due to the presence of waves between neighboring vortices. The combination of these two mechanisms results in enhanced axial dispersion. We showed that hysteresis may occur between consecutive regimes depending on flow history and this may have a significant effect on mixing for a given Reynolds number. The axial dispersion coefficient Dx evolution along the successive flow states was investigated thanks to dye Residence Time Distribution measurements (RTD) and particle tracking (DNS). Both experimental and numerical results have confirmed the significant effect of the flow structure and history on axial dispersion. Our study confirmed that the commonly used 1-parameter chemical engineering models (e

  13. Rapid, accurate, and non-invasive measurement of zebrafish axial length and other eye dimensions using SD-OCT allows longitudinal analysis of myopia and emmetropization.

    Directory of Open Access Journals (Sweden)

    Ross F Collery

    Full Text Available Refractive errors in vision can be caused by aberrant axial length of the eye, irregular corneal shape, or lens abnormalities. Causes of eye length overgrowth include multiple genetic loci, and visual parameters. We evaluate zebrafish as a potential animal model for studies of the genetic, cellular, and signaling basis of emmetropization and myopia. Axial length and other eye dimensions of zebrafish were measured using spectral domain-optical coherence tomography (SD-OCT. We used ocular lens and body metrics to normalize and compare eye size and relative refractive error (difference between observed retinal radial length and controls in wild-type and lrp2 zebrafish. Zebrafish were dark-reared to assess effects of visual deprivation on eye size. Two relative measurements, ocular axial length to body length and axial length to lens diameter, were found to accurately normalize comparisons of eye sizes between different sized fish (R2=0.9548, R2=0.9921. Ray-traced focal lengths of wild-type zebrafish lenses were equal to their retinal radii, while lrp2 eyes had longer retinal radii than focal lengths. Both genetic mutation (lrp2 and environmental manipulation (dark-rearing caused elongated eye axes. lrp2 mutants had relative refractive errors of -0.327 compared to wild-types, and dark-reared wild-type fish had relative refractive errors of -0.132 compared to light-reared siblings. Therefore, zebrafish eye anatomy (axial length, lens radius, retinal radius can be rapidly and accurately measured by SD-OCT, facilitating longitudinal studies of regulated eye growth and emmetropization. Specifically, genes homologous to human myopia candidates may be modified, inactivated or overexpressed in zebrafish, and myopia-sensitizing conditions used to probe gene-environment interactions. Our studies provide foundation for such investigations into genetic contributions that control eye size and impact refractive errors.

  14. Plasma tomography of higher resolution

    International Nuclear Information System (INIS)

    New microwave tomography scheme for plasma diagnostic is suggested - ray based diffraction tomography, which promises to reach a resolution, close to a diffraction limit. Besides, this scheme is less sensitive to the amplitude fluctuations as compared with traditional phase tomography. The method, which was suggested earlier for the ionosphere applications, can be helpful also for revealing of electron density inhomogeneities in a hot plasma. The algorithm, used for processing, is able to reveal small-scale plasma inhomogeneities of characteristic length, comparable with microwave wavelength, that is up to 1-3 cm. (author)

  15. Computed tomography of the paranasal sinus for endonasal sinus surgery

    International Nuclear Information System (INIS)

    In a retrospective study 170 computed tomographies recorded in patients with chronic sinus disease were evaluated. The extent of sinus disease and the involvement of the different paranasalsinuses were well seen. Up to now 50 patients have undergone surgical treatment. The coincidence of the preoperative CT with the intraoperative findings was about 90%. Anatomic particularities of the paranasal sinus in an individual patient may predispose to recurrent sinusitis or mean there is an increased risk of intraoperative complications. The main risk factors are a far lateral location of the posterior ethmoid cells (28.8%), a much lower position of the cibriform plate in comparison to the ethmoid roof (11.8%), and extensive lateral aeration of the sphenoidal sinus (1.2%). All patients should undergo CT scanning in coronal and axial planes prior to endonasal sinus surgery. This gives a guide for detection of inflammatory lesions and anatomic variations or anomalies, thus making it possible to prevent intraoperative complications. (orig.)

  16. A non-commutative time-frequency tomography

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The characterization of non-stationary signal requires joint time and frequency information. However, time and frequency are a pair of non-commuting variables that cannot constitute a joint probability density in the time-frequency plane. The time-frequency distributions have difficult interpretation problems arising from negative and complex values or spurious components. In this paper, we get time-frequency information from the marginal distributions in rotated directions in the time-frequency plane. The rigorous probability interpretation of the marginal distributions is without any ambiguities. This time-frequency transformation is similar to the computerized axial tomography (CT or CAT) and is applied to signal analysis and signal detection and reveals a lot of advantages especially in the signal detection of the low signal/noise (S/N).

  17. Optical Coherence Tomography of Retinal and Choroidal Tumors

    Directory of Open Access Journals (Sweden)

    Emil Anthony T. Say

    2011-01-01

    Full Text Available Optical coherence tomography (OCT has revolutionized the field of ophthalmology since its introduction 20 years ago. Originally intended primarily for retina specialists to image the macula, it has found its role in other subspecialties that include glaucoma, cornea, and ocular oncology. In ocular oncology, OCT provides axial resolution to approximately 7 microns with cross-sectional images of the retina, delivering valuable information on the effects of intraocular tumors on the retinal architecture. Some effects include retinal edema, subretinal fluid, retinal atrophy, photoreceptor loss, outer retinal thinning, and retinal pigment epithelial detachment. With more advanced technology, OCT now provides imaging deeper into the choroid using a technique called enhanced depth imaging. This allows characterization of the thickness and reflective quality of small (<3 mm thick choroidal lesions including choroidal nevus and melanoma. Future improvements in image resolution and depth will allow better understanding of the mechanisms of visual loss, tumor growth, and tumor management.

  18. Anterior Segment Tomography with the Cirrus Optical Coherence Tomography

    OpenAIRE

    Rodrigues, Eduardo B.; Margara Johanson; Fernando M Penha

    2012-01-01

    Optical coherence tomography (OCT) is an optical acquisition method to examine biological tissues. In recent years, OCT has become an important imaging technology used in diagnosing and following macular pathologies. Further development enabled application of optical coherence tomography in evaluation of the integrity of the nerve fiber layer, optic nerve cupping, anterior chamber angle, or corneal topography. In this manuscript we overview the use of OCT in the clinical practice to enable co...

  19. AXIAL RATIO OF EDGE-ON SPIRAL GALAXIES AS A TEST FOR BRIGHT RADIO HALOS

    Energy Technology Data Exchange (ETDEWEB)

    Singal, J.; Jones, E.; Dunlap, H. [Physics Department, University of Richmond 28 Westhampton Way, Richmond, VA 23173 (United States); Kogut, A., E-mail: jsingal@richmond.edu [Code 665, NASA Goddard Space Flight Center Greenbelt, MD 20771 (United States)

    2015-01-20

    We use surface brightness contour maps of nearby edge-on spiral galaxies to determine whether extended bright radio halos are common. In particular, we test a recent model of the spatial structure of the diffuse radio continuum by Subrahmanyan and Cowsik which posits that a substantial fraction of the observed high-latitude surface brightness originates from an extended Galactic halo of uniform emissivity. Measurements of the axial ratio of emission contours within a sample of normal spiral galaxies at 1500 MHz and below show no evidence for such a bright, extended radio halo. Either the Galaxy is atypical compared to nearby quiescent spirals or the bulk of the observed high-latitude emission does not originate from this type of extended halo. (letters)

  20. Report on the Dynamical Evolution of an Axially Symmetric Quasar Model

    Indian Academy of Sciences (India)

    N. J. Papadopoulos; N. D. Caranicolas

    2006-12-01

    The role of the angular momentum in the regular or chaotic character of motion in an axially symmetric quasar model is examined. It is found that, for a given value of the critical angular momentum , there are two values of the mass of the nucleus for which transition from regular to chaotic motion occurs. The [-] relationship shows a linear dependence for the time independent model and an exponential dependence for the evolving model. Both cases are explained using theoretical arguments together with some numerical evidence. The evolution of the orbits is studied, as mass is transported from the disk to the nucleus. The results are compared with the outcomes derived for galactic models with massive nuclei.