Medline Plus

... stenosis. It looks from the transesophageal and the 3-D echo that most of the problem is really ... posterior leaflet, which you can see on the 3-D echo image is a major source. The anterior ...

Energy Technology Data Exchange (ETDEWEB)

The applications of neutron reflectometry to study dynamic phenomena at surface and interfaces have been restricted so far. This was mainly due to the low intensity of neutron sources, but now high-intensity spallation neutron sources are under construction in Japan (J-PARC) and US (SNS). We are planning to install a spin-echo option on the J-PARC neutron reflectometer with horizontal sample geometry for studies of dynamics of surfaces and interfaces. This option is based on the resonance spin-echo method and aimed at dynamics up to hundreds of nanoseconds. In this contribution, the plan and status of development are introduced together with the principle and characteristics of this option.

British Library Electronic Table of Contents (United Kingdom)

This paper introduces the application of independent component analysis mixture modelling (ICAMM) in non-destructive testing (NDT). The application consists of discriminating patterns for material quality control from homogeneous and defective materials inspected by impact-echo testing. This problem is modelled as a mixture of independent component analysis (ICA) models, representing a class of defective or homogeneous material by an ICA model whose parameters are learned from the impact-echo signal spectrum. These parameters define a kind of particular signature for the different defects. The proposed procedure is intended to exploit to the maximum the information obtained with the cost efficiency of only a single impact. To illustrate this capability, four levels of classification detail...

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Proton magnetic resonance spectroscopy (MRS) measures concentrations of metabolites in vivo and provides a powerful method for identifying tumours. MRS has not entered routine clinical use partly due to the difficulty of analysing the spectra. To create a straightforward method for interpreting short-echo-time MRS of childhood cerebellar tumours. Single-voxel MRS (1.5-T Siemens Symphony NUM4, TR/TE 1,500/30 ms) was performed at presentation in 30 children with cerebellar tumours. The MRS results were analysed for comparison with histological diagnosis. Peak heights for N-acetyl aspartate (NAA), creatine (Cr), choline (Cho) and myo-inositol (mIns) were determined and receiver operator characteristic curves used to select ratios that best discriminated between the tumour types. The method was implemented by a group of clinicians and scientists, blinded to the results. A total of 27 MRS studies met the quality control criteria. NAA/Cr >4.0 ...

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Detecting a camouflaged target in a visually noisy background depends on the ability of the observer to discriminate the target from the surrounding terrain. Visible laser irradiation at less than damage levels can act as a masking source by compromising or reducing the observer's ability to resolve differences in the visual scene. Previous research has examined this concept by investigating laser flash effects on: acuity (size discrimination); tracking (motion discrimination); visual sensitivity (color); and contrast sensitivity functions (luminance contrast). In all cases, flashes from continuous-wave (CW) sources have proven more effective visually than pulsed (Q-switched) sources, when compared on peak-energy criteria (i.e., MPE), even though Q-switched lasers induce damage at lower energy doses. Additionally, the inherent safety of ultra-short ...

Energy Technology Data Exchange (ETDEWEB)

This is a prompt report. These days the importance of acquiring knowledge about the structure from the lower crust down to the upper mantle is often discussed with reference taken to Hyogo-ken Nanbu Earthquake. The Hidaka collision belt where the lower crust is exposed on the surface is a rare phenomenon in the world and has been the subject of seismic survey. As a part of the survey, experiments are conducted by the use of vibrations produced by Vibroseis and dynamite sources. Every one of the shot records (20-second record) from the two types of vibration sources contains a clear echo in the vicinity of 16 seconds supposedly from a level deeper than 40 kilometers, not to mention reflections from shallow levels. Although some studies have to be conducted before the reflecting geological boundary (possibly the upper mantle) of the echo near the 16-second point can be identified, yet this is probably the ...

KoreaScience (Korea)

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International Nuclear Information System (INIS)

... interval analyzers counting techniques discriminators electronic circuits

Norwegian Open Research Archives (NORA)

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Energy Technology Data Exchange (ETDEWEB)

Because the number of neutrons and gamma rays and the energy spectrum of particles from spontaneous fission are well characterized for {sup 252}Cf, it can be used as a timed source of fission neutrons and gamma rays. The first such usage incorporated a {sup 252}Cf source into gas scintillators. This paper describes a timed source of neutrons and gamma rays made by depositing {sup 252}Cf on one electrode of a parallel plate ionization chamber that can then be used for determining detection-system characteristics. The emission time of neutrons from spontaneous fission has also been determined by recording the emission time of prompt gamma rays from a {sup 252}Cf source (not incorporated into a detector) adjacent to the surface of a solid or liquid scintillator. This well characterized source of neutrons can thus be used as a randomly pulsed source for a variety of ...

Science.gov (United States)

Characteristics of inertia gravity waves associated with convection are investigated in the lower stratosphere using high-resolution radiosonde data observed from 18 June to 15 July of 2005 and 2007 in Korea. Three-dimensional ray-tracing model and reanalysis data are used to investigate the propagation and the sources of the observed waves. The observed waves associated with convections are discriminated based on the existence of convections when and where the rays reach the average height range of convective clouds. Waves observed in 2005 and 2007 show similar spectral characteristics, but wave energy in 2007 is significantly larger than in 2005. The observed waves propagate from three source regions: the northeastern, southeastern, and western regions around Korea. They show preferential propagation directions based on their sources, and convections from the western region generate larger-amplitude ...

CERN Document Server

Using spectral hole-burning-based ultraslow group velocity in a dilute solid medium, we report enhanced photon echo efficiency three orders of magnitude higher than that in a nonslow light regime. The enhancement is due to exponentially increased absorption of an optical data pulse owing to the enhanced photon-atom interaction in an ultraslow light regime, whereas echo reabsorption is negligibly small due to group-velocity dependent population depletion.

Energy Technology Data Exchange (ETDEWEB)

We have examined the theory of NMR multiple echoes developed for solid {sup 3}He to determine whether multiple echoes could be observed in solid hydrogen. We were particularly interested in the possibility of testing for low frequency quantum tunneling motions in solid hydrogen by the observation of multiple echoes. We find that for easily accessible nuclear spin polarizations, P > 12%, multiple echoes would be observed for HD impurities in solid parahydrogen if motional narrowing is effective in increasing the HD nuclear spin-spin relaxation time T{sub 2} to the order of 1 msec. These values for T{sub 2}, which have been observed for HD impurity concentrations of the order of 1%, are larger than the calculated rigid lattice values and can be attributed to quantum tunneling at frequencies of the order of 1kHz.

International Nuclear Information System (INIS)

T_2 weighted ultra-short turbo spin echo sequences were used in five individuals with variations in echo times, delayed triggering and echo intervals. To reduce movement artifacts all examinations were carried out with ECG and respiratory triggering. The sequences giving optimal image quality were then employed in 19 patients having various pulmonary abnormalities. Image resolutions, artifacts, image contrasts and diagnostic value were then judged by two observers and compared with CT. In the first study, a diastole-triggered UTSE sequence with the shortest echo proved optimal (T_E=90 ms, T_R=2-4 s, echo=9 ms, turbo factor=19). In the patient series studied, MRT was inferior to CT with regard to resolution and number of artifacts, but better in respect of contrast and diagnostic value. Using UTSE of the lung, MRT can produce images of good quality. Compared with CT, contrast is ...

Science.gov (United States)

This data set contains data from in situ infrared thermometer measurements ... Surface temperature was measured using an Apogee Infrared Thermometer from 23 ...

Science.gov (United States)

A univibrator and a pulse height discriminator using tunnel diodes and backward diodes are described, along with their applications in pulse shaping and fast coincidence technique. The main advantages achieved are simplicity of design and speed. The characteristics of the two diodes are shown. (auth)

Energy Technology Data Exchange (ETDEWEB)

Qualitative interpretation of data of different nature and sources, based on segmentation techniques such as discriminant analysis, is useful to characterize and monitor hydrocarbon reservoirs. In order to make this interpretation more reliable, it is necessary to characterize uncertainties attached to data and then, to propagate them in the interpretation work-flow. In this thesis, uncertainties are represented by intervals, because usually, little is known about input data errors. The uncertainty characterization issue is dealt with specifically for each case study. The uncertainty propagation issue is treated by a new technique, based on interval analysis, which consists in extending to intervals various popular approaches (non parametric, quadratic and linear) to discriminant analysis: Firstly, a learning phase allows calibrating an imprecise classifying model on the basis of pre-interpreted data. If the quality of this ...

Science.gov (United States)

Throughout their history, Americans have believed that citizens' fulfillment of their individual duties in a participatory democracy is at least partly met through the forming of groups around important societal issues. Given the complex nature of political socialization, this study investigated identifiable determinants of social action that might be used to advantage in educating young people for citizenship in a democracy. This study attempted to differentiate among junior high, high school and college students (N=517) who were inclined and not inclined to act on their concerns about nuclear threat with selected demographic, psychological, political, and educational variables. The results of a discriminant functional analysis indicated that in comparison with the non-action group, students in the action group were characterized by reporting less trust in government, more exposure to sources of nuclear war information, more political ...

International Nuclear Information System (INIS)

Artifical valve prostheses are often regarded as a contraindication for magnetic resonance imaging (MRI), although preliminary in vitro studies suggested, that patients with these metallic implants might safely undergo MR examination. This study reports on the experience with a group of 89 patients with 100 heart valve prostheses who were examined by spin-echo MR and gradient-echo MR. MR examination was performed in all patients without complications. The spin-echo sequence showed advantages in the depiction of anatomical structures like paravalvular abcesses. Anatomical structures adjacent to the artificial valve were clearly visivle and the metal components of the valves showes no or only small artifacts. Artifacts were accentuated when using gradient-echo sequences. Gradient-echo sequences provided valuable information regarding the presence of valvular insufficiency. ...

British Library Electronic Table of Contents (United Kingdom)

The objective of this study is to test the validity of sex determination in children and adolescents using lateral radiographic cephalometry and discriminant function analysis. Fifty male and 50 female cephalograms of Taiwanese children were used (males and females with mean age of 15.52???1.38 and 15.67???1.54?years, respectively). Twenty-two cephalometric measurements were performed using computerized cephalometry. Statistical analysis shows that all measurements were sexually dimorphic (p?discriminant function analysis. A stepwise discriminant procedure selected seven of the nine variables, producing 95% accuracy in sex determination. Resubstitution classification reveals the same discriminant rat...

Energy Technology Data Exchange (ETDEWEB)

Gel dosimetry is a new dosimetry method applied in radiation therapy. Gel dosimeters consist of a radiation sensitive gel, which can integrate absorbed doses from several radiation sources or beams. The dose to the gel can be evaluated by magnetic resonance imaging (MRI), a procedure that is the focus of the present thesis. A robust tool for the evaluation of the nonuniformity in MRI has been developed, the Deviation Image method. Unlike previously presented methods, the Deviation Image method includes all nonuniformity variations across a phantom surface and is insensitive to stochastic noise. Methods for the estimation of stochastic noise were analyzed in terms of sensitivity to nonuniformities. A method that averages the stochastic noise level over five regions over the phantom surface, and a method that assesses the stochastic noise level from the background, were found to be the methods of choice. Pronounced MR image nonuniformity variation with repetition and ...

International Nuclear Information System (INIS)

This paper investigates regional and age-related changes in metabolite ratios using image-localized H-1 MR spectroscopy in children. Twenty-seven children referred for MR imaging of the brain underwent localized H-1 MR spectroscopy with a Siemens 1.5-T whole-body imager. Localization to 2 x 2 x 2-cm volumes of interest was achieved with a stimulated-echo or spin-echo technique. Repetition times of 1,600 and 5,000 msec were used, with echo times varying between 68 and 270 msec. Total combined imaging and spectroscopy times were 90-120 minutes.

International Nuclear Information System (INIS)

Ten patients with traumatic femoral neck fracture were studied with MR imaging (0.5 T, Magnetom, Siemens): unenhanced (multiecho, TR/TE = 1,600/30--240 [repetition time/echo time, msec]; gradient echo, TR/TE = 315/14, #theta# = 90 degrees) and Gd-DTPA enhanced (0.1 mM/kg body weight, Magnevist, Schering; gradient echo, TR/TE = 315/14, #theta# = 90 degrees). MR images were compared with clinical-radiographic findings. Digital subtraction angiography of the femoral head (FH) in five patients showed complete interruption of blood supply to the FH in three patients (signal intensity of FH did not increase on postcontrast images) and intact FH arteries in two patients (FH signal increased on postcontrast images, as did the healthy-side signal).

Science.gov (United States)

The abuse of volatile solvents may be due to their ability to produce an intoxication similar to that produced by classical central nervous system depressants such as the barbiturates and ethanol. To evaluate this hypothesis, mice were trained to discriminate pentobarbital from saline injections in a two-lever operant task. Stimulus generalization was examined following 20-min inhalation exposures to toluene (300-5400 ppm). In 8 of 10 subjects, pentobarbital-lever responding occurred following toluene exposure indicating an overlap in the discriminative stimulus properties of toluene and pentobarbital.

UK PubMed Central (United Kingdom)

Chimpanzee (Pan troglodytes) agonistic screams are graded vocal signals that are produced in a context-specific manner. Screams given by aggressors and victims can be discriminated...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

T{sub 2} weighted ultra-short turbo spin echo sequences were used in five individuals with variations in echo times, delayed triggering and echo intervals. To reduce movement artifacts all examinations were carried out with ECG and respiratory triggering. The sequences giving optimal image quality were then employed in 19 patients having various pulmonary abnormalities. Image resolutions, artifacts, image contrasts and diagnostic value were then judged by two observers and compared with CT. In the first study, a diastole-triggered UTSE sequence with the shortest echo proved optimal (T{sub E}=90 ms, T{sub R}=2-4 s, echo=9 ms, turbo factor=19). In the patient series studied, MRT was inferior to CT with regard to resolution and number of artifacts, but better in respect of contrast and diagnostic value. Using UTSE of the lung, MRT can produce images of good quality. Compared with CT, ...

Energy Technology Data Exchange (ETDEWEB)

Purpose: In vitro evaluation of possible deflection and heating of present-day prosthetic heart valves, 12 technical and 5 biological, were investigated using a 1.5 Tesla Siemens Vision system. Deflection was measured at the edge of a 1.5 Tesla superconducting magnet. Each valve was then submerged in a vial of a 1/1 electrolyte solution and temperature was measured before and after imaging with a turbo-spin-echo sequence (TR 5200 ms, TE 138 ms, Flip angle 180 C, acquisition time 10.5 minutes, length of echo train 29). MR imaging was performed with phase encoding parallel and perpendicular to the plane of the valves. Results: None of the investigated prosthetic heart valves was deflected. The maximal observed temperature rise was 0.5 C. During MR investigation of the prostheses, artifacts caused by metallic parts were less evident using a spin-echo sequence than a gradient-echo sequence. Conclusions: ...

Energy Technology Data Exchange (ETDEWEB)

Personnel radiation monitoring is essential to the operation of any nuclear facility and work in this area continues to strive for an accurate determination of personnel dose. In particular recent attention has been focused upon the need to improve the accuracy of neutron dosimetry, mainly because of their high Relative Biological Effectiveness. In this work the feasibility of using the NE-213 liquid scintillation detector as an efficient neutron/..gamma.. ray radiation monitor is demonstrated. Derivative method spectrum unfolding used in MATXUF for on-line analysis of fast neutron spectra has also been applied to real time ..gamma.. spectrum unfolding (MATXUF2), making possible simultaneous on-line monitoring of both fast neutrons and gammas. To eliminate the negative fluxes in the unfolded ..gamma.. spectra created by the photopeak-Compton edge combination in the plateau portion of the knee response, correcting equations using a linearized approximation to the electron recoil ...

Science.gov (United States)

Personnel radiation monitoring is essential to the operation of any nuclear facility and work in this area continues to strive for an accurate determination of personnel dose. In particular recent attention has been focused upon the need to improve the accuracy of neutron dosimetry, mainly because of their high Relative Biological Effectiveness. In this work the feasibility of using the NE-213 liquid scintillation detector as an efficient neutron/gamma ray radiation monitor is demonstrated. Derivative method spectrum unfolding used in MATXUF for on-line analysis of fast neutron spectra has also been applied to real time gamma spectrum unfolding (MATXUF2), making possible simultaneous on-line monitoring of both fast neutrons and gammas. To eliminate the negative fluxes in the unfolded gamma spectra created by the photopeak-compton edge combination in the plateau portion of the knee response, correcting equations using a linearized approximation to the electron recoil spectrum has been ...

Energy Technology Data Exchange (ETDEWEB)

The security of ports and transportation is of utmost importance for the development of economy and the security of a nation. Among the necessary actions to ensure the security of ports and borders, the inspection of containers is one of the most time consuming and expensive procedures. Potential threats are the illegal traffic of radioactive materials that could be employed for the construction of weapons, as uranium and plutonium. New techniques for the inspections of containers should be fast, allow the detection and identification of dangerous materials, and be non-invasive, to reduce costs and delays. We propose to build a large surface photon and neutron detector based on plastic scintillator to identify the presence of fissile or fertile material inside a container. The detector consists of scintillator bars, wrapped in thin foils of reflecting material containing gadolinium for neutron capture and arranged in planes separated by few-millimeter-thick lead sheets. The total ...

Energy Technology Data Exchange (ETDEWEB)

In the 14 MeV Neutron Laboratory, we have continued the development of a facility that is now the only one of its kind in operation in the United States. We have refined the klystron bunching system described in last year's report to the point that 1.2 nanosecond pulses have been directly measured. We have tested the pulse shape discrimination capability of our primary NE 213 neutron detector. We have converted the RF sweeper section of the beamline to a frequency of 1 MHz to replace the function of the high voltage pulser described in last year's report which proved to be difficult to maintain and unreliable in its operation. We have also overcome several other significant experimental difficulties, including a major problem with a vacuum leak in the main accelerator column. We have completed additional testing to prove the remainder of the generation and measurement systems, but overcoming some of these experimental difficulties has delayed the ...

International Nuclear Information System (INIS)

An attempt to determine lysozyme hydration by employing a proton nuclear magnetic resonance (NMR) spin-echo technique and to correlated such measurements with the 20 "0C sorption equilibrium data is made. Determinations of specific site hydration for lysozyme, as well as proton NMR transverse relaxation rates for five different types of water populations in the lysozyme-water system, are presented over the whole range of lysozyme concentrations. The proton spin-echo NMR results are consistent with a three-component analysis of the sorption isotherm up to 70% water content, above which two additional water populations are identified by 360-MHz proton NMR spin-echoes. On the basis of the proton NMR results, a major component (III) of the lysozyme sorption isotherm is assigned to the water trapped between lysozyem molecules, whose relaxation rate is increased by diffusion barriers. The trapped water population dominates the ...

International Nuclear Information System (INIS)

The use of magnetic resonance imaging for diagnosis and the preoperative staging of renal cell carconoma was evaluated in 79 patients with 88 tumors. Gradient-echo and spin-echo images before and after intravenous administration of Gadolinium DTPA were compared with the results of computed tomography (CT) and histologic staging. The two imaging techniques had comparable results: T-stage was predicted correctly with CT in 78%.4% and with MRI in 84.0% of the cases, while the N-stage was accurately assessed in 81.8% and 79.5%, respectively. MRI had some advantages in diagnosing perirental tumor spread and in excluding an infiltration beyond Gerota's fascia. Therefore, MRI is a true alternative to CT for staging large renal cell carcinomas and especially for patients with contraindications for iodinated contrast agents. (orig.).

CERN Document Server

We investigate decoherence in quantum systems coupled via dephasing-type interactions to an arbitrary environment with chaotic underlying classical dynamics. The coherences of the reduced state of the central system written in the preferential energy eigenbasis are quantum Loschmidt echoes, which in the strong coupling regime are characterized at long times scales by fluctuations around a constant mean value. We show that due to the chaotic dynamics of the environment, the mean value and the width of the Loschmidt echo fluctuations are inversely proportional to the quantity we define as the effective Hilbert space dimension of the environment, which in general is smaller than the dimension of the entire available Hilbert space. Nevertheless, in the semiclassical regime this effective Hilbert space dimension is in general large, in which case even a chaotic environment with few degrees of freedom produces decoherence without revivals. Moreover ...

UK PubMed Central (United Kingdom)

Virulent strains of Newcastle disease virus ([NDV] also known as avian paramyxovirus type 1) can be discriminated from low-virulence strains by the presence of multiple basic amino acid residues at...Full Text Available

Science.gov (United States)

... M. Taylor, T. Kurt Kyser. (2009) Feather isotope analysis discriminates age-classes of Western, Least, and Semipalmated sandpipers when plumage ... ...

International Nuclear Information System (INIS)

The cosmic ray neutron spectrum at sea level has been measured by the method of pulse shape discrimination in anthracene scintillator. The exponent of the differential spectrum was found to be 2.2+-0.1. (Auth.).

UK PubMed Central (United Kingdom)

Animals in a variety of taxa discriminate between a greater quantity and a lesser quantity of the same object, an ability that is referred to as relative numerousness judgment. For example,...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundA previous study showed for Anopheles gambiae s.s. a gradation of feeding preference on common plant species growing in a malaria holoendemic area in western...Full Text Available

UK PubMed Central (United Kingdom)

Double cones (DCs) are the most common cone types in fish, reptiles and birds. It has been suggested that DCs are used for achromatic tasks such as luminance, motion and polarization vision. Here we...Full Text Available

UK PubMed Central (United Kingdom)

After discrimination training on a multiple variable-interval extinction schedule of food reinforcement, pigeons were placed on the uncued or mixed version of the same schedule and allowed to make...Full Text Available

UK PubMed Central (United Kingdom)

Essential in mitosis, the human Kinesin-5 protein is a target for >80 classes of allosteric compounds that bind to a surface-exposed site formed by the L5 loop. Not established is why there...Full Text Available

Science.gov (United States)

...treated for leukemia. B' s physician, who is employed by the HMO, is considering a treatment plan that includes six-mercaptopurine, a drug for treating leukemia in most children. However, the drug could be fatal if taken by a small percentage of...

Energy Technology Data Exchange (ETDEWEB)

Already, MR Imaging is superior in diagnostic imaging of joints in many cases; however, there have been recent developments, which are the subjects of this paper. With gradient-echo sequences acquired in 3D technique, it is possible to produce high-resolution images of joints in acceptable scantime, because gradient-echo sequences are less time-consuming than convential SE sequences. With the acquisition of two echoes, phase difference between water and fat protons have to be considered. 3D Imaging is capable of displaying complex pathology in a superior way, which should be useful in preoperative planning. Tissue contrast is altered by fat saturation or magnetization transfer in order to achieve better conspicuity of lesions. Although diagnostic value of some of these options is not yet clear and further clinical studies are needed, they are a promising possibility for improving MR Imaging of the joints. (orig.) [Deutsch] ...

UK PubMed Central (United Kingdom)

A pulsed field gradient spin echo sequence has been incorporated in a nuclear magnetic resonance (NMR) imaging experiment to provide an image contrast dependent on local molecular self-diffusion. The...Full Text Available

International Nuclear Information System (INIS)

The Polarized Gamma-ray Observer (PoGOLite) is a balloon-borne instrument that will measure gamma-ray polarization in the energy range 25-80 keV from astronomical sources such as pulsars, accretion discs and jets from active galactic nuclei. The two additional parameters provided by such observations, polarization angle and degree, will allow these objects to be studied in a new way, providing information about their emission mechanisms and geometries. The instrument measures azimuthal scattering angles of photons within a close packed array of phoswich detector cells (PDCs) based on coincident detection of Compton scattering and photoelectric absorption. Each PDC comprises three different scintillating components and combines photon detection, active collimation and bottom anticoincidence into one single unit. The three parts are viewed by a photomultiplier tube (PMT) and pulse shape discrimination is used to identify signals from dierent ...

Science.gov (United States)

This paper proposes a new pattern recognition system employing optical joint transform correlation (JTC) technique which offers a great number of advantages over similar digital techniques, including very fast operation, simple architecture and capability of updating the reference image in real time. The proposed JTC technique incorporates a synthetic discriminant function (SDF) of the target image estimated from different training images to make the pattern recognition performance invariant to noise and distortion. It then involves four different phase-shifted versions of the same target SDF reference image, which are individually joint transform correlated with the given input scene. When the correlation signals are combined, it produces a single cross-correlation peak corresponding to each potential target present in the given input scene. The proposed technique also includes a fringe-adjusted filter to generate a delta-like correlation peak with high ...

International Nuclear Information System (INIS)

Cerebral maturation in the human fetal brain was investigated by in utero localized proton magnetic resonance spectroscopy (MRS). Spectra were acquired on a clinical MR system operating at 1.5 T. Body phased array coils (four coils) were used in combination with spinal coils (two coils). The size of the nominal volume of interest (VOI) was 4.5 cm"3 (20 mm x 15 mm x 15 mm). The MRS acquisitions were performed using a spin echo sequence at short and long echo times (TE = 30 ms and 135 ms) with a VOI located within the cerebral hemisphere at the level of the centrum semiovale. A significant reduction in myo-inositol and choline and an increase in N-acetylaspartate were observed with progressive age. The normal MR spectroscopy data reported here will help to determine whether brain metabolism is altered, especially when subtle anatomic changes are observed on conventional images. Some examples of impaired fetal brain development studied by MRS are ...

International Nuclear Information System (INIS)

Purpose: To determine the diagnostic value of high resolution MR imaging with a circularly polarised (c.p.) body phased-array coil for the staging of pelvic lymph nodes in cervical carcinoma. Material and methods: 42 patients with histologically proven carcinoma of the cervix were studied on a 1.5 T scanner by using a c.p. body phased-array coil. The imaging protocol included T_2-weighted turbo-spin-echo (TSE) and T_1-weighted spin-echo sequences pre and post IV application of Gd-DTPA; slice thickness was 5-7 mm and pixel size 0.53 mm"2. Lymph nodes with a diameter of #>=#8 mm were considered to have metastatic involvement. MR imaging results were compared with histopathologic findings. Results: MR imaging showed enlarged lymph nodes (#>=# 8 mm) in 16 of 18 patients with histologic proof of lymph node metastases (sensitivity 89%). In 22 of 24 cases MR findings were true negative (specificity 92%). Diagnostic accuracy was 91%. Conclusion: ...

Energy Technology Data Exchange (ETDEWEB)

Introduction: The goal of this study was to compare contrast-enhanced T1-weighted Flash and Turbo-Flash sequences with conventional spin-echo sequences as a basis for planning high-precision radiotherapy. Methods: A total of 25 consecutive patients with different intracranial tumors and a disrupted blood-brain barrier were studied. T1-weighted Flash, Turbo-Flash and conventional spin-echo images were evaluated after controlled 30-s infusion of 0.1 mmol/kg body weight of Gd-DTPA. The evaluation of the three sequences included the measurement of the signal- and contrast-to-noise ratios, the visual inspection of the tumors and artifacts, and the measurement of tumor size. Results: The signal- and contrast-to-noise ratios were significantly (P<0.05-0.01) lower for Flash and Turbo-Flash than for conventional spin-echo sequences. However, visual inspection of the contrast-enhancing tumors revealed in 23 and 24 of 25 lesions of ...

Energy Technology Data Exchange (ETDEWEB)

A study has been conducted on the statistics of detected neutrons that leaked from four subcritical reflected, enriched-uranium assemblies, to explore the feasibility of developing a criticality warning system based on neutron noise analysis. Studies were conducted on three possible discriminators, i.e., three signatures that might be used to discriminate among assemblies of various multiplications. The noise analysis techniques studied performed well enough in deeply subcritical situations to deserve testing in an applications environment. They have a good chance of detecting changes in reactivity that are potentially dangerous. One can expect sharpest results when doing comparisons, i.e., when comparing two records, one taken in the past under circumstances known to be normal and one taken now to search for change.

Energy Technology Data Exchange (ETDEWEB)

The defects localization in power cables follows several steps: identification, pre-localization and precise localization. Pre-localization methods, other than echo-metry, are presented first: bridge methods, particular case of low voltage networks, future perspectives. Then, the precise localization methods are described: magneto-acoustic method, audible frequencies method. The particular case of underwater and high-voltage cables is considered too (oil and gas leaks detection). (J.S.)

International Nuclear Information System (INIS)

This paper reports, to complement current knowledge on brain development, late regional brain maturation assessed with quantitative MR imaging. Axial and coronal head spin-echo (SE) images were obtained in 60 healthy individuals aged 5--56 years, with a double-echo, flow compensated imaging sequence obtained with a 1.5-T Magnetom spectroscopy and imaging system. T2-weighted images were calculated from the intensity differences in SE images at echo times (TEs) of 15 and 90 msec (TR = 2.5 second). The mean T2 values were determined at 16 sites in each cerebral hemisphere. T2 values of the six frontal subcortical white matter (FSCWM) sites and of the internal capsule (IC) were evaluated. Mean T2 values in the IC decreased until age 10 years, whereas this decrease continued in the FSCWM past age 15 years before reaching a plateau. Differential age-dependent patterns of mean T2 values emerged between the six FSCWM sites. The ...

Wastenet

... Wanting to help a charity is commendable but the main focus of generosity should be the people in front of you, not your choice of spiritual overlord - especially so if the group is being funded with money from taxpayers. Recommend? (44) Report abuse | Link ...

Energy Technology Data Exchange (ETDEWEB)

The transition radiation detector (TRD) for the D{Phi} experiment is currently in operation at Fermilab. Transition radiation production, which has been clearly observed in the collider data, makes the TRD a valuable tool to discriminate electrons and hadrons. We describe an algorithm based on the truncated energy, and illustrate its use for top signal and background. (authors). 7 refs., 6 figs., 2 tabs.

International Nuclear Information System (INIS)

A multi-spectral Schottky barrier infrared detector array in which individual pixels of radiation from a remote radiating object are detected by two or more Schottky barrier infrared radiation detectors each having a different spectral response so as to provide a ''color'' discrimination for the array.

Energy Technology Data Exchange (ETDEWEB)

The intrasphenoid form of basal cephalocele is uncommon. We describe the clinical, CT and MRI findings in two cases presenting in middle age with persistent cerebrospinal fluid rhinorrhoea. Emphasis is placed upon the imaging findings which aid in discrimination of intrasphenoidal cephalocele from more common causes of a sphenoid sinus mass. (orig.)

International Nuclear Information System (INIS)

The convolution/superposition algorithm for computing dose from photon beams in radiation therapy planning requires knowledge of the energy spectrum. The algorithm can compute the dose for a polyenergetic beam as the weighted sum of the individual dose contributions from monoenergetic beams. In this study we exploit interface effects apparent in the dose distributions to discriminate among spectra of high energy photon beams. We have studied the sensitivity of the depth dose distribution to the energy components using a hypothetical beam for various field sizes and depths in water and water-lung-water media. Six theoretical spectra were simulated. We compared depth dose data from these spectra using three quantitative measures which are inherently free of normalization ambiguities: for homogeneous water, the ratio D_2_0/D_1_0 and a logarithmic derivative in the buildup region LD_b_u_i_l_d_-_u_p and for inhomogeneous lung/water, the lung correction factor (CF). It ...

UK PubMed Central (United Kingdom)

1. Using a grease-gap recording technique we have investigated the effects of some antagonists of P2-purinoceptors on the depolarization of the rat isolated superior cervical ganglion evoked by 100...Full Text Available

International Nuclear Information System (INIS)

A four-stage scoring system for brain maturation was established with MR imaging. First, gyration and myelination were analyzed in 50 anamnestically normal children (32-240 weeks postconceptional age). Subsequently 60 patients (same age range) with birth asphyxia, seizures, or developmental delays were evaluated analogously. T1- and T2-weighted images (500/30 and 3,000/120 [repetition time msec/echo time msec]) were obtained with a 2.35-T magnet in all children. Whereas gyration abnormalities were seen in some patients, all handicapped children presented with delayed myelination. In conclusion, prospective staging of brain development (gyration and myelination) is possible and is best obtained with T2-weighted images.

Energy Technology Data Exchange (ETDEWEB)

Purpose: To evaluate a T{sub 2}-weighted URSE sequence for the assessment of pulmonary infiltrations in comparison to CT. Methods: 28 MRT scans of 22 patients with confirmed pneumonia were recorded on a 1.5 Tesla apparatus with an expiratory and diastolic triggered, T{sub 2}-weighted ultrafast-spin-echo sequence in axial slice mode with the following parameters: TR{sub eff}/T{sub E}/Turbofactor 2000-4000/90 ms/21-23; slice thickness/separation 6/0.6 mm; FOV 360 mm; 24 slices. 24 spiral CTs (sice thickness/table advance: 1-2 mm/10 mm) were available for comparison. The separate evaluation of MRTs and CTs was performed by three radiologists in a consensus procedure with regard to pulmonary lesions (e.g., infiltration, round foci, net patterns) and image quality of the MRTs (4-step scale). Results: In 71% of the cases the CTs and MRTs agreed with the diagnosis and representation of the lesions, in 25% MRT was superior. MRT was better for the detection of pulmonary ...

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Purpose: To determine the diagnostic value of high resolution MR imaging with a circularly polarised (c.p.) body phased-array coil for the staging of pelvic lymph nodes in cervical carcinoma. Material and methods: 42 patients with histologically proven carcinoma of the cervix were studied on a 1.5 T scanner by using a c.p. body phased-array coil. The imaging protocol included T{sub 2}-weighted turbo-spin-echo (TSE) and T{sub 1}-weighted spin-echo sequences pre and post IV application of Gd-DTPA; slice thickness was 5-7 mm and pixel size 0.53 mm{sup 2}. Lymph nodes with a diameter of {>=}8 mm were considered to have metastatic involvement. MR imaging results were compared with histopathologic findings. Results: MR imaging showed enlarged lymph nodes ({>=} 8 mm) in 16 of 18 patients with histologic proof of lymph node metastases (sensitivity 89%). In 22 of 24 cases MR findings were true negative (specificity 92%). Diagnostic accuracy was ...

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An array of sonic transducers, useful for medical ultrasonic imaging, has individual sections thereof separately coupled for forming separate beams of sonic energy which converge, respectively, to separate foci along a common axis of the beams. The ratio of the diameter of the radiating aperture of the array relative to a wavelength of the sonic energy is chosen to provide a moderate degree of focusing so that the depth of field at one focus blends with the depth of field of the next focus. Thereby, there is formed a continuous region of substantially uniform intensity of sonic radiation along the common beam axis. Circuitry is provided for selecting one or more specific foci dependent on the bounds of a selected region to be insonified. Upon reception of sonic energy, circuitry is provided for selecting one or more specific foci as a function of the time of travel of an echo from a subject being observed to approximate a continuously varying focus in accordance ...

British Library Electronic Table of Contents (United Kingdom)

Purpose To evaluate the methods of applicator reconstruction in 3D MR-based planning for brachytherapy of cervical cancer, and to investigate applicator shifts and changes in DVH parameters during PDR treatment. Methods For each application MR scans with applicator in situ were made: three T2-weighted (4.5mm slices) Turbo Spin Echo (TSE) scans and a balanced Steady State Free Precession scan (1.5mm). Three observers tested two applicator reconstruction methods: (A) directly on the bSSFP scan and (B) on a resampled combination of the three T2-weighted scans. For 10 patients MR imaging was repeated on the second day of each PDR fraction to determine applicator shifts and changes in DVH parameters. Results For both applicator reconstruction methods the interobserver variation for the DVH para...

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In this paper heavy metal pollution at an abandoned Italian pyrite mine has been investigated by comparing total concentrations and speciation of heavy metals (Fe, Cu, Mn, Zn, Pb and As) in a red mud sample and a river sediment. Acid digestions show that all the investigated heavy metals present larger concentrations in the sediment than in the tailing. A modified Tessier's procedure has been used to discriminate heavy metal bound to organic fraction from those originally present in the mineral sulphide matrix and to detect a possible trend of metal mobilisation from red mud to river sediment. Sequential extractions on bulk and size fractionated samples denote that sediment samples present larger percent concentrations of the investigated heavy metals in the first extractive steps (I-IV) especially in lower dimension size fractionated samples suggesting that heavy metals in the sediment are significantly bound by superficial adsorption mechanisms. - ...

Science.gov (United States)

Anxiety is a common symptom during ethanol withdrawal contributing to its continuous abuse and alcoholism. Ethanol withdrawal in rats produces an interoceptive discriminative stimulus (IDS) similar to that produced by the anxiogenic drug pentylenetetrazol (PTZ). This stimulus peaks at 12 hours after last dose of ethanol and thereafter the IDS is detected for several days (protracted withdrawal) by sensitization to a probe drug. previously, the authors have shown that during the protracted withdrawal, the IDS is enhanced by GABA receptor antagonists suggesting alteration of brain GABA systems. This report provides further evidence that chronic ethanol alters GABAergic systems. Rats were trained to discriminate PTZ (20 mg/kg, ip) from saline. Diazepam, pentobarbital and phenobarbital blocked the PTZ-IDS dose dependently. Ethanol, 4.5% w/v, was then given in a nutritionally complete diet for a week. On termination of the ethanol diet, rats ...

International Nuclear Information System (INIS)

Materials Scientists need information on the kinetics of the microstructural evolution processes that determine the finished microstructure, and hence the properties, of any material. E.g. recrystallisation, grain growth and phase changes. Such kinetic information requires reliable discrimination of differently oriented crystallites and/or different crystal phases coupled with useful spatial resolution and temporal resolution (i.e. high frame rates). These imaging results must be realised from a hot and changing specimen, in an instrument that is compatible with that hot specimen and with a practical specimen heater. Focused Ion Beams (FIB) offer strong contrast between crystallites and phases, and hence offer the ability to discriminate between these features even while imaging at fast frame rates, however their compatibility with hot specimens was unproven. Here we report results from a novel combination of FIB with an in-situ heating stage, ...

International Nuclear Information System (INIS)

In many experiments involving fast neutrons generated in nuclear reactions initiated by accelerator produced charged particle beams, it is important to be able to determine accurately the neutron yield from the target. A detector suitable for such applications should have: a constant efficiency over a large energy range; a fast time response; and the ability to discriminate between gamma rays and neutrons. The authors have constructed a open-quotes black neutron detectorclose quotes based on the design of Poenitz that has these characteristics. At the Lowell Van de Graaff accelerator laboratory neutrons are produced via the "7Li(p,n)"7Be reaction using a pulsed proton beam which impinges on metallic lithium targets. The pulsed beam enables the detector to be used in a time-of-flight spectrometer. Use of BC501 liquid scintillator permits neutron-gamma discrimination. The scintillator is viewed by five RCA 48796 photo tubes. The detector is ...

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Apparatus and method for selective measurement of tritium oxide in an environment which may include other radioactive components and gamma radiation, the measurement including the selective separation of tritium oxide from a sample gas through a membrane into a counting gas, the generation of electrical pulses individually representative by rise times of tritium oxide and other radioactivity in the counting gas, separation of the pulses by rise times, and counting of those pulses representative of tritium oxide. The invention further includes the separate measurement of any tritium in the sample gas by oxidizing the tritium to tritium oxide and carrying out a second separation and analysis procedure as described above.

CERN Document Server

The Electromagnetic Calorimeter (ECAL) of the AMS-02 experiment is a lead-scintillating fibers sampling calorimeter characterized by high granularity that allows to image the longitudinal and lateral showers development, a key issue to provide high electron/hadron discrimination. The light collection system and the FE electronics are designed to let the calorimeter operate over a wide energy range from few GeV up to 1 TeV. A full-scale prototype of the e.m. calorimeter was tested at CERN in October 2001 using electrons and pions beams with energy ranging from 3 to 100 GeV. Effective sampling thickness, linearity and energy resolution were measured. (8 refs).

International Nuclear Information System (INIS)

The ability of the Packard 2000 CA/LL liquid scintillation counter to reduce background count rates relies on pulse shape/duration analysis in which short duration organic scintillation events are discriminated from longer duration non-quenchable background events. A consequence of this is a loss in the counting efficiency. The results of this investigation indicate that much of the lost efficiency can be regained by sharpening the true #beta#"- pulse widths via the use of different scintillant combinations and by certain counter modifications. (author).

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The paper describes an application of the tree classification method Random Forest (RF), as used in the analysis of data from the ground-based gamma telescope MAGIC. In such telescopes, cosmic gamma-rays are observed and have to be discriminated against a dominating background of hadronic cosmic-ray particles. We describe the application of RF for this gamma/hadron separation. The RF method often shows superior performance in comparison with traditional semi-empirical techniques. Critical issues of the method and its implementation are discussed. An application of the RF method for estimation of a continuous parameter from related variables, rather than discrete classes, is also discussed.

CERN Document Server

PAMELA is a space telescope orbiting around the Earth since June 2006. The scientific objectives addressed by the mission are the measurement of the antiprotons and positrons spectra in cosmic rays, the hunt for anti-nuclei as well as the determination of light nuclei fluxes from Hydrogen to Oxygen in a wide energy range and with very high statistics. In this paper the charge discrimination capabilities of the PAMELA Time-Of-Flight system for light nuclei, determined during a beam test calibration, will be presented.

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No abstract prepared

Science.gov (United States)

This document presents the findings of an extensive study of the ore mining and dressing industry, for the purpose of developing effluent limitations guidelines for existing point sources and standards for performance new sources, to implement Sections 30...

Science.gov (United States)

...false Priorities for use of Government supply sources. 208.002 Section 208...ACQUISITION PLANNING REQUIRED SOURCES OF SUPPLIES AND SERVICES 208.002 Priorities for use of Government supply sources. (a)(1)(v)...

International Nuclear Information System (INIS)

CT of the gastrointestinal tract is commonly performed after administration of a high-density diluted iodinated oral contrast material. However, because if inadequate mixing of the contrast material with the gastrointestinal contents, pseudotumor and poor mucosal visualization are frequently shown on abdominal CT. To overcome these problem, 10% corn oil emulsion (COE) is tested as an alternative oral contrast agent in 40 patients. We analyse patients tolerance, gastric mucosal visualization and discrimination of pancreas from the duodenal C-loop to 10% COE in 40 patients compared with those obtained from 35 patients, who was received high-density diluted iodinated oral contrast agent (gastrografin). The results are as follows : 1. Patients' tolerance to 10% COE is similar to that to conventional oral contrast agent. 2. Image of the gastric mucosa from patients receiving 10% COE is superior to that receiving oral contrast agent. 3. The ...

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Purpose: To evaluate MR artifacts of carotid artery stents and to optimize stent properties and sequence parameters. Material and Methods: Four carotid artery stents - Wallstent (mediloy), Precise (nitinol), ACCULINK (nitinol) and a stent prototype (nitinol) - were investigated in a flow model of the cervical vessels. The model was made of silicon tubing and a flow pump that produces realistic flow curves of the carotid artery. To investigate the effects of magnetic susceptibility and radiofrequency induced shielding artifacts, turbo spin echo and gradient echo sequences as well as CE-MRAs were measured. To improve the visualization of the stent lumen in a CE-MRA, flip angle as well as geometry and covering of the stent prototype were altered. Results: Susceptibility artifacts in stents of the carotid artery only influence the lumen visualization at the proximal and distal end of the braided mediloy stent. A change of stent coverings has no ...

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The purpose of this study was to correlate MR imaging findings with pathology in experimental hyperoxia-induced acute lung injury, which has similar pathology to diffuse alveolar damage (DAD). Seventeen Yorkshire pigs were studied. These animals were exposed to more than 80% oxygen for 24, 48, 72, and 96 hours in a sealed cage. The lungs were removed and inflated with air infused through the trachea, and then examined by both MRI and high-resolution CT (HRCT). T1-weighted spin-echo (T1WSE), T2-weighted fast (T2WFSE), and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences were performed. Severity in MR findings and signal-to-noise ratios (SNR) on MR images were well correlated with pathological scores. CT values were also correlated well with pathologic scores. Abnormal SNR values were obtained from a pathological score of 5, whereas abnormal CT values were obtained from a pathological score of 15. Furthermore, significant ...

International Nuclear Information System (INIS)

To find out the sonographic findings that are useful to differentiate hepatic abscess from peripheral cholangiocarcinoma. Twenty-two hepatic abscesses and 22 peripheral cholangiocarcinomas which had been confirmed histologically were included in this study. Objective points were echo characteristics of the lesion, internal septation, presence of peripheral low echoic rim, demarcation from normal liver(well or poorly defined), posterior enhancement, multiplicity, dilatation of bile duct(obstructive or non-obstructive), intrahepatic duct stone, pleural effusion, and intra-abdominal fluid collection. Echo characteristics of the lesion were classified in-to four types. Type I; Predominantly echogenic with hypoechoic portion, type II; Echogenic without hypoechoic portion, type III; Predominantly hypoechoic with echogenic portion, type IV; Hypoechoic without echogenic portion. 1)Nine abscesses and 2 peripheral cholangiocarcinomas were type ...

International Nuclear Information System (INIS)

Background. In multiple myeloma 5 different infiltration patterns can be differentiated: 1. Normal appearance of bone marrow, 2. focal involvement, 3. homogeneous diffuse infiltration, 4. combined diffuse and focal infiltration, 5. 'salt-and pepper' pattern with inhomogeneous bone marrow with interposition of fat islands. Methods. For the fast and total acquisition of all patterns a combination of a T1-weighted spin echo sequence and a fat suppression technique is superior. The focal involvement is clearly demonstrated as areas of high signal intensity on e.g. STIR images. Diffuse involvement can be quantified objectively by calculation of the percentage of signal intensity increase after contrast material injection. MRI is superior to X-ray in focal and diffuse involvement. With ultrafast sequences a 'screening' of the whole red bone marrow as for myeloma infiltration is possible. Prognosis. In prognosis studies diffuse infiltration is inferior to focal ...

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The purpose of this study is to investigate the role of femoral marrow MR imaging as predictor of outcome for hemopoietic stem cell transplantation (HSCT) in beta-thalassemia major. MR imaging of the proximal femur, including T1- and T2-weighted spin echo and short-tau inversion recovery and in-phase and out-of-phase fast field echo images, was prospectively performed in 27 thalassemia major patients being prepared for HSCT. The area of red marrow and its percentage of the proximal femur were measured, and the presence of marrow hemosiderosis was assessed. Age-adjusted multivariate logistic regression was used to determine the relationship between red marrow area percentage and marrow hemosiderosis and HSCT outcome. Red area percentage were less in patients with successful (90.25{+-}4.14%) compared to unsuccessful transplants (94.54% {+-}2.93%; p=0.01). Red marrow area percentage correlated positively with duration of symptoms(r=0.428, p=0.026) ...

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Purpose: The aim of this study was to evaluate the accuracy of MRI in the measurement of cartilage thickness of the ankle joint in comparison to pathologic and histologic specimens. Patients and methods: The ankle joints of four fresh cadaver feet were imaged on a 1.5 T MR-unit in the coronal plane. Standard T{sub 1}-weighted spin echo (SE) and a T{sub 1}-weighted 3D-GE (FLASH-3D) sequence with fat saturation were applied. Following MR imaging, the talus was explanted and cut parallel to the MR images for macroscopic evaluation and histologic specimens were prepared. MRI measurements of the cartilage thickness of the talus were carried out in two ways: Without and with consideration of a transition zone of intermediate signal intensity between hyperintense cartilage and hypointense cortical bone. The data were compared with the anatomic specimens as the gold standard expressing the difference as a percentage value. On histologic specimens thickness of deep ...

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A spherical-geometry, self-extraction negative ion source has been designed and fabricated. The source utilizes direct surface ionization to form negative ion beams resulting from interactions between high electron affinity gaseous elemental or molecular materials and a negatively biased, spherical-sector LaB{sub 6} surface ionizer maintained at {similar to}1300 K. The design features of this source and principles upon which the source is based are discussed in this report.

UK PubMed Central (United Kingdom)

The reference medium for brachytherapy dose measurements is water. Accuracy of dose measurements of brachytherapy sources is critically dependent on precise measurement of the source–detector...Full Text Available

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AbstractPurpose: To implement and examine the feasibility of a three-dimensional (3D) ultrashort TE (UTE) sequence on a 7 Tesla (T) clinical MR scanner in comparison with 3T MRI at high isotropic resolution. Materials and Methods: Using an in-house built saddle coil at both field strengths we have imaged mid-diaphysial sections of five fresh cadaveric specimens of the distal tibia. An additional in vivo scan was performed at 7 Tesla using a quadrature knee coil. Results: Using the same type of saddle coil at both field strengths, a significant increase in SNR at 7T compared with 3T (factor 1.7) was found. Significantly shorter T2* values were found at the higher field strength (T2* = 552.2 126 s at 7T versus T2* = 1163 391 s at 3T). Conclusion: UHF MRI at 7T has great potential for imaging...

CERN Document Server

We report the results of a worldwide campaign to observe WZ Sagittae during its 2001 superoutburst. After a 23-year slumber at V=15.5, the star rose within 2 days to a peak brightness of 8.2, and showed a main eruption lasting 25 days. The return to quiescence was punctuated by 12 small eruptions, of ~1 mag amplitude and 2 day recurrence time; these "echo outbursts" are of uncertain origin, but somewhat resemble the normal outbursts of dwarf novae. After 52 days, the star began a slow decline to quiescence. Periodic waves in the light curve closely followed the pattern seen in the 1978 superoutburst: a strong orbital signal dominated the first 12 days, followed by a powerful /common superhump/ at 0.05721(5) d, 0.92(8)% longer than P_orb. The latter endured for at least 90 days, although probably mutating into a "late" superhump with a slightly longer mean period [0.05736(5) d]. The superhump appeared to follow familiar rules for such phenomena in dwarf novae, with ...

International Nuclear Information System (INIS)

Glasses in the system (95-x) [0.25 Na2O-0.75 B2O3]-x P2O5-5 Fe2O3 (0?x?15 mol%), have been prepared by the melt quenching technique. Elastic properties and FT-IR spectroscopic studies have been employed to study the role of P2O5 on the structure of the glass system. Elastic properties Poisson's ratio, micro-hardness and Debye temperature have been investigated using sound wave velocity measurements at 4 MHz (both longitudinal and shear) at room temperature. The results showed that the density and the molar volume increase as both sound velocities and the determined glass transition temperatures decrease with increasing the contents of P2O5. Infrared spectra of the glasses reveal that the borate network consists of diborate units and is affected by the increase in the concentration of P2O5 content as a second network former. These results are interpreted in terms of the replacement of the diborate units with B-O-B bridges by phosphate units with non-bridging oxygens (NBOs). Therefore, ...

British Library Electronic Table of Contents (United Kingdom)

A novel method for non-destructive intramuscular fat (IMF) estimation via spectral ultrasound backscatter analysis of signals obtained from pig carcasses early post mortem is described. A commercial hand-held ultrasound device (center frequency: 2.7MHz) was modified to focus the sound beam to the longissimus muscle at the 2nd/3rd last rib. Time-resolved ultrasound backscatter signals of loin muscle were recorded 45minp.m. on 82 pig carcass sides. Backfat width (d"B"F=18.9+/-3.8mm) and muscle attenuation (@a"m"u"s"c"l"e=.77+/-.15dBMHz^-^1cm^-^1) were assessed from the measured pulse echo data. Other propagation properties of skin, backfat and muscle tissue obtained in a previous investigation were incorporated into the signal pre-processing to minimize parameter estimation artifacts. Spectr...

Energy Technology Data Exchange (ETDEWEB)

This document gathers a series of very short articles concerning nuclear industry around the world. Areva company is investing 30 million euros in its Chalon-Saint-Marcel plant, it is the consequence of the extension of service life of nuclear power plants in the Usa. Areva holds 40% of the American market concerning the replacement of steam generators and 50% of that concerning the replacement of closure heads. The Obrigheim nuclear power plant was definitely closed down on may 2004, this decommissioning is a step forward in the German policy of progressively stepping out of nuclear energy. Chinese authorities are willing to construct 40 nuclear reactors in 15 years, despite that, the contribution of nuclear energy to the generation of electricity will reach only 4% in 2020. In 2007 Cea will begin the construction works of a new research reactor (Jules Horowitz reactor) in the Cadarache site. Prices of the yellow cake have been going up during the last years: from 9 dollar the pound ...

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MRT criteria have been developed to distinguish between tumour and implant material following examination of 50 patients who had transsphenoidal hypophysectomies for tumours. Judgements were based on the postoperative hormonal status and the operation notes. Following contrast injection of Gd-DTPA and using T[sub 1] weighted spin-echo sequences, implant material appeared as sandwich-like, linear or circular structures. Residual recurrent tumour produced homogenous or non-homogenous aspects without marginal enhancement in 84% of cases. Postoperative displacement of the infundibulum to the opposite side was observed in 73% of patients with tumour remnants. Sensitivity of MRT was 70%, specificity 95%. There was a positive predictive value of 94% and a negative predictive value of 72% with an accuracy of 81%. This provides assistance in differentiating between tumour remnants and implant material. MRT is recommended as a method of examination for hypophyseal tumours to ...

International Nuclear Information System (INIS)

Purpose: With intracranial tumors a flat, contrast-enhancing, probably dural structure adjacent to the tumor can occasionally be observed on gadolinium-DTPA enhanced MR images. Therefore we have attempted to evaluate a tumor infiltration of this enthancement on MRI. Material and Methods: This study included 50 patients. 19 patients had a dural thickening at the tumor base (13 meningiomas and 6 metastases), while 31 patients did not (12 meningiomas and 19 metastases). Studies included plane T_2-weighted spin echo (SE) images as well as T_1-weighted axial, coronal, or sagittal plains with and without contrast agent. Histopathological examinations, were done on the tumor base adjacent to the dura mater. Results: 7 of 12 meningiomas showed a meningeal thickening on MRI with histopathologically proven tumor infiltration as did also 5 of 6 metastases. But 3 of 12 meningiomas and 15 of 19 metastases without dural thickening at the tumor base also showed tumor invasion ...

British Library Electronic Table of Contents (United Kingdom)

The aim of this study was to estimate the sensitivity of biomarkers of stress and exposure in the bivalve mollusk Anodonta cygnea to spontaneous anthropogenic activities typical for the Western Ukraine. Three sites were examined during spring, summer and autumn: an agricultural site (A); the cooling pond of nuclear power plant (N) and a forestry close to the municipal water inlet (F). Common temporal changes of a battery of biochemical markers in the gills and hemolymph and morphological characteristics were shown by discriminant functional analysis. Classification trees built on the basis of the screened biomarkers demonstrated persistent peculiarities at each site: genotoxicity (nuclear abnormalities) at site A and endocrine disruption (high levels of vitellogenin-like proteins (Vtg-LP) ...

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The detectors used in the TS93 balloon flight produced a large volume of information for each cosmic ray trigger. Some of the data was visual in nature, other portions contained energy deposition and timing information. The data sets are amenable to conventional analysis techniques but there is no assurance that conventional techniques make full use of subtle correlations and relations amongst the detector responses. With the advent of neural network technologies, particularly adept at classification of complex phenomena, it would seem appropriate to explore the utility of neural network techniques to classify particles observed with the instruments. In this paper neural network based methodology for signal/background discrimination in a cosmic ray space experiment is discussed. Results are presented for electron and positron classification in the TS93 flight data set and will be compared to conventional analyses.

Science.gov (United States)

This article examines relevant government policy documents on education and culture and discovers that Nigerian education authorities do not "discriminate" against art and culture in its articulation of educational policies per se, but lack of administrative machinery or political will has resulted in the deprivation of the Nigerian child in the process of creative activity in early childhood development. The article argues that lack of creative ability in our educational products is perhaps a major setback in the nation's quest for industrial and technological development. In this article a new art curriculum for elementary schools is advocated as a means of engaging the young child in order to attain functional educational skills necessary in the world of work.

CERN Document Server

In a first paper (Forni & Aghanim 1999), we developed several statistical discriminators to test the non-gaussian nature of a signal. These tests are based on the study of the coefficients in a wavelet decomposition basis. In this paper, we apply them in a cosmological context, to the study of the nature of the Cosmic Microwave Background (CMB) anisotropies. The latter represent the superposition of primary anisotropy imprints of the initial density perturbations and secondary ones due to photon interactions after recombination. In an inflationary scenario (standard Cold Dark Matter) with gaussian distributed fluctuations, we study the statistical signature of the secondary effects. More specifically, we investigate the dominant effects arising from the Compton scattering of CMB photons in ionised regions of the Universe: the Sunyaev-Zel'dovich effect of galaxy clusters and the effects of a spatially inhomogeneous re-ionisation of the Universe. Our study ...

International Nuclear Information System (INIS)

MRI findings in 13 patients with monolateral parotid tumor were compared with US, sialographic and CT findings. MRI did not allow an accurate diagnosis in 2 patients with diffuse chronic parotitis. MRI was superior to CT in 1 case in defining the intraglandular site of the lesion, and in 2 patients in showing the extraglandular involvement. MRI proved to be superior to CT thanks to its contrast resolution and to multiplanar imaging. MRI high contrast resolution made it possible to demonstrate neoplastic lesions of 4 mm in diameter. The lesion has low signal intensity on T1-weighted images and high signal intensity on T2-weighted. Parotid tumors cannot be characterized by signal intensity alone: only morphology allows to discriminate between benign and malignant lesions. To conclude, US is a screening method, while MRI is helpful in detecting multifocal lesions and in evaluating the tumor extent.

Energy Technology Data Exchange (ETDEWEB)

Thermoluminescence of inorganic dust extract from herbs and spices has been demonstrated to be a useful method to discriminate irradiated food products as well as to estimate the total dose exposure. The time evolution of infrared stimulated luminescence has been systematically investigated in potassium feldspar and albite minerals subjected to different doses of gamma irradiation (ranging from 0 to 8 kGy). Experimental results reveal a 300-600 nm signal which is greatly intensified for irradiated samples, following the same irradiation dose dependence observed in thermoluminescence. The luminescence intensity disappears after few seconds of illumination, following a time evolution which is proportional to (1 + Bt){sup -P}. The influence of both B and P factors upon the irradiation dose has been systematically analysed. (author)

Energy Technology Data Exchange (ETDEWEB)

The neutron-induced fission cross-section of {sup 233}U has been measured at the CERN n-TOF facility relative to the standard fission cross-section of {sup 235}U between 0.5 and 20MeV. The experiment was performed with a fast ionization chamber for the detection of the fission fragments and to discriminate against {alpha} -particles from the natural radioactivity of the samples. The high instantaneous flux and the low background of the n-TOF facility result in data with uncertainties of {approx} 3%, which were found in good agreement with previous experiments. The high quality of the present results allows to improve the evaluation of the {sup 233}U (n,f) cross-section and, consequently, the design of energy systems based on the Th/U cycle. (orig.)

Energy Technology Data Exchange (ETDEWEB)

We describe in detail the space of the two Kaehler parameters of the Calabi-Yau manifold P[sub 4][sup (1,1,1,6,9)][D. R. Morrison, 1993] by exploiting mirror symmetry. The large complex structure limit of the mirror, which corresponds to the classical large radius limit, is found by studying the monodromy of the periods about the discriminant locus, the boundary of the moduli space corresponding to singular Calabi-Yau manifolds. A symplectic basis of periods is found and the action of the Sp(6, Z) generators of the modular group is determined. From the mirror map we compute the instanton expansion of the Yukawa couplings and the generalized N=2 index, arriving at the numbers of instantons of genus zero and genus one of each bidegree. We find that these numbers can be negative, even in genus zero. We also investigate an SL(2, Z) symmetry that acts on a boundary of the moduli space. ((orig.))

British Library Electronic Table of Contents (United Kingdom)

The key factors of enzymatic lysis of cells are the interaction between the enzyme and the cell - catalytic and non-catalytic adsorption of enzyme on cell surface. Here, the studies of lysis of intact Escherichia coli cells by chicken egg white lysozyme were performed. It was found that the ionic strength has a dual effect onto the system. On the one hand, the desorption constant of the enzyme increases with the increase of the solution ionic strength, which results in a better enzyme performance. On the other hand, due to the higher osmosis, the cell lysis rate decreases with the increasing of ionic strength of the system. It was found that pH 8.6 and 30mM NaCl are optimal conditions for lysis of E. coli cells by lysozyme.

British Library Electronic Table of Contents (United Kingdom)

Vignon, M. (2011) Inference in morphological taxonomy using collinear data and small sample sizes: Monogenean sclerites (Platyhelminthes) as a case study. -Zoologica Scripta, 40, 306-316. Taxonomists and evolutionary biologists frequently use a combination of morphological measurements to distinguish between species and investigate local adaptation. However, the entire set of characters often displays various degrees of collinearity. This paper discusses the effect of using collinear data in morphological taxonomy and ways to handle multicollinearity in a classification context, with special consideration for small sample size. In addition, I propose a robust and easy-to-use combination of dimension reduction using partial least squares (PLS) with traditional discriminant methods for morph...

British Library Electronic Table of Contents (United Kingdom)

Women who have academic careers in engineering have successfully navigated the social identity threats that prevent many other women from feeling that they belong in science, technology, engineering, and math fields. In this research, we examined what factors may be related to resilience in these academic environments. Female academics in engineering and nonengineering fields watched a fictitious conference video depicting either an unbalanced ratio of men to women or a balanced ratio. Subjective measures of identity threat were collected. Past experience with discrimination, positive experience with female role models, family support, and general social support were associated with a greater sense of belonging to or desire to participate in the conference. These variables all buffered neg...

British Library Electronic Table of Contents (United Kingdom)

SummaryBackgroundCandida albicans is one of the most important etiologic agents causing superficial and deep fungal infections. For prevention of candidiasis, it is important to develop a rapid system that discriminates C. albicans at the strain level.ObjectiveTo develop a system that can identify C. albicans at the strain level.MethodsGenomic DNAs were purified from 179 clinical isolates of C. albicans, and were used as templates for PCR amplification of 25S rDNA and ALT repeats in repetitive sequences (RPSs). PCR products generated from ALT repeats were digested with EcoRI and/or ClaI in order to study the relationships between restriction profiles and amplification profiles.ResultsOne hundred and seventy nine clinical isolates were grouped into genotypes A (92 isolates), B (38 isolates)...

British Library Electronic Table of Contents (United Kingdom)

Roller bearing is one of the most widely used elements in rotary machines. Condition monitoring of such elements is conceived as pattern recognition problem. Pattern recognition has three main phases: feature extraction, feature selection and feature classification. Histogram features can be used for fault diagnosis of roller bearing. This paper presents the use of decision tree for selecting best few histogram features (bin ranges) that will discriminate the fault conditions of the bearing from given train samples. These features are extracted from vibration signals. A rule set is formed from the extracted features and fed to a fuzzy classifier. The rule set necessary for building the fuzzy classifier is obtained largely by intuition and domain knowledge. This paper also presents the usag...

International Nuclear Information System (INIS)

Neutron capture #gamma#-ray spectra have been measured at 11 average neutron energies from 10 to 530 keV in /sup 88/Sr using a 20 x 15 cm NaI detector with time-of-flight discrimination of background events. The partial radiation widths and the calculated partial valence widths are compared for the strong p-wave resonances at 287 and 321 keV and found to be highly correlated. At these energies, the spectra are dominated by strong transitions to low-lying single particle states, in confirmation of the role of valence capture in the 3p region. However, the data do not support this mechanism at <508> keV.

British Library Electronic Table of Contents (United Kingdom)

Abstract When both sexes mate with multiple partners, theory predicts that males should adjust their investment in ejaculates in response to the risk and/or intensity of sperm competition. Here, we demonstrate that, in the harlequin beetle riding pseudoscorpion, Cordylochernes scorpioides, males use cues deposited on females by previous males to distinguish between virgin, once-mated, and multiply-mated females and adjust sperm allocation accordingly. Sperm number declined in direct proportion to the number of previous males, with virgin females receiving nearly three times more sperm than females exposed to three previous males. Given the lack of first-male sperm precedence in C.scorpioides, this pattern is not consistent with current sperm competition models and appears best explained by...

British Library Electronic Table of Contents (United Kingdom)

Purpose: The DBA/2J mice have been used as an animal model for human pigmentary glaucoma. However, these mice develop various degrees of disease symptoms at different ages, making it difficult to detect pathological changes of retinal degeneration at glaucoma onset. The purpose of this study is to develop a non-invasive assay to identify individual mice that develop visual deficits. Materials and Methods: We apply two behavioral tests, a swimming test of visual discrimination and a test of optomotor response, to identify glaucomatous DBA/2J mice. We then examine whether the elevation of intraocular pressure (IOP), the common risk factor for glaucoma, affects visual performances of the DBA/2J mice. We further compare the retinal ganglion cell death, one of the signature glaucoma symptoms, i...

International Nuclear Information System (INIS)

This paper describes stable strontium as composed of four stable isotopes ( Sr 88, Sr 87, Sr 86, and Sr 84), of which Sr 88 contributes more than 82% to its composition. Strontium exists in three crystalline, plymorphic forms; face-centered cubic alpha form, hexagonal beta form and body-centered cubic gamma form. Strontium occupies in many physicochemical aspects an intermediate position between calcium and barium, as does the solubility of strontium salts. As a result of its oxidation potential, strontium readily forms oxides, halides, and sulfide. The author proposes that the slight discrimination against strontium incorporation into bony tissues may be due to the difference in ionic potential (14%) between strontium and calcium. Ionic potential is an indicator of the strength of ionic bonds: strontium has a smaller ratio of ionic charge to ionic radius when compared with calcium.

British Library Electronic Table of Contents (United Kingdom)

Nuclear magnetic resonance (NMR) techniques coupled with multivariate data analysis were used to conduct monitoring of biochemical changes of black raspberry fruits at different stages of maturation and under various extraction and NMR dissolution solvent conditions: extraction with 50% methanol and D"2O as an NMR dissolution solvent, extraction with 50% methanol and 50% methanol-d"4 as an NMR dissolution solvent, and extraction with 100% ethyl acetate and 100% methanol-d"4 as an NMR dissolution solvent. Partial least-squares discriminant analysis reliably distinguished black raspberry fruits according to the maturation stage, whereby the relative levels of various compounds such as amino acids, organic acids, sugars and phenolic compounds were compared using analysis of variance. Sucrose ...

British Library Electronic Table of Contents (United Kingdom)

From the COMBO-17 digital sky survey data, 1,231 faint blue galaxies with photometric redshifts of 0.1discriminating those misjudged low-redshift galaxies by using only the optical data. We have studied a...

International Nuclear Information System (INIS)

A car-borne NaI(Tl) spectrometric system was used together with a "1"3"7Cs source to obtain realistic data in the search for unshielded and semi-shielded orphan sources. The potassium-stripped counts (PSC) method was used to estimate the influence by the shielding on the detection ability. A reduction of about 5% in the critical distance was obtained for the semi-shielded source. A curve fitting method was also developed and evaluated. Results from the curve fitting method showed inferior ability to find the source compared to the PSC method. However, it can be a useful complementary tool, for characterisation of the source shielding, and estimation of the distance from the road.

Energy Technology Data Exchange (ETDEWEB)

Parallel imaging and echo sharing techniques have markedly reduced the acquisition times for MRI of large volumes. Dynamic 2 and 3-dimensional data sets of the chest with high temporal resolution (up to 10 images/s with single slice and 2 volume/s) allow an analysis of respiratory motion of the lungs and tumors. Time-resolved 2D series in preselected planes can be used to observe respiratory motion during free breathing or after respiratory commands, e.g. to exclude chest wall invasion by a tumor or for diagnosing impairment of respiratory mechanics. Time-resolved 3D-series (4D-MRI) allow monitoring of the spatial displacement of the lungs and tumors as a whole volume. Present limitations such as an overestimation of tumor size and an underestimation of displacement due to a limited temporal resolution are expected to be overcome with further technical developments. However, 4D-MRI already appears to be the appropriate tool to select patients for motion-adapted ...

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Polarized electron sources for high energy accelerators took a significant step forward with the introduction of a new laser-driven photocathode source for the SLC in 1992. With an electron beam polarization of >80% and with {approximately}99% uptime during continuous operation, this source is a key factor in the success of the current SLC high-energy physics program. The SLC source performance is used to illustrate both the capabilities and the limitations of solid-state sources. The beam requirements for future colliders are similar to that of the SLC with the addition in most cases of multiple-bunch operation. A design for the next generation accelerator source that can improve the operational characteristics and at least minimize some of the inherent limitations of present sources is presented. Finally, the possibilities for producing ...

UK PubMed Central (United Kingdom)

Sources of industrial emissions of 1,3-butadiene are discussed both by process (production, consumers) and type (equipment leaks, point sources). Quantification of the emissions are presented, as reported...Full Text Available

Science.gov (United States)

Jan 25, 2006 ... Source positions are determined using matched-filter and centroiding .... The upper 1-sigma statistical error in the full-band counts. ...

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Alluvial fans along the east side of central Death Valley are being actively back-tilted along the Death Valley fault zone. Initial modelling of the Copper Canyon and Furnace Creek fans led to recognition of distinct segments. Field reconnaissance and aerial photo mapping were conducted to check model results and improve segment discrimination. Surface roughness, relative position, vegetation distribution, and drainage patterns provided independent evidence for segment discrimination. Subsequent modelling of individual segments produced a range of tilt values from 0.275[degree] to 0.559[degree] down to the northeast. Continued analysis of these fan segments is concentrated on: (1) assigning confidence and error values to the tilt values; and (2) dating individual segments. Further work will compare the tilt rates of east-side fans with those from the west. The mean squared error (MSE) is currently being used as a first order assessment of the ...

International Nuclear Information System (INIS)

A new generation of transmit-receive single-pass probes, denoted as C6 or X probe, was field tested during the Gentilly II, 2000 steam generator tube inspection. This probe has a performance equivalent to rotating probes and can be used for tubesheet and full-length inspection at an inspection speed equivalent to that of bobbin probes. Existing C3 transmit-receive probes have been demonstrated to be effective in detecting circumferential cracks. The C5 probe can detect both circumferential and axial cracks and volumetric defects but cannot discriminate between them. The C6 probe expands on the capabilities of both probes in a single probe head. It can simultaneously detect and discriminate between circumferential and axial cracks to satisfy different plugging criteria. It has excellent coverage, good defect detectability, and improved sizing and characterization. Probe data is displayed in C-scan format so that the amount of data to be analyzed ...

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A summary of the topics covered in papers presented at the 1995 Brookhaven joint conference on production, neutralization, and application of negative ion beams is given. The conference topics covered included plasma ion sources, plasma seeding of these sources for increased ion production, beam extraction and transport, computer simulation and design studies, and operation of existing and experimental ion source facilities. Application of the sources to accelerator, tokamak, and thin film deposition are discussed. (AIP) {copyright} {ital 1996 American Institute of Physics.}

KoreaScience (Korea)

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No abstract prepared.

International Nuclear Information System (INIS)

Short communication.

International Nuclear Information System (INIS)

An electron accelerator unit is described for electron beam therapy, comprising: a source of an electron beam; means for finally directing at least a portion of the beam to a therapy site, the directing means being mechanically independent of, and electrically isolated from, the source, and having a target area; and means for aligning the source with the directing means, the aligning means comprising means for projecting at least one beam of light from the source toward the target area.

KoreaScience (Korea)

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KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

Materials for the construction of cold neutron sources must satisfy a range of demands. The cryogenic temperature and irradiation create a severe environment. Candidate materials are identified and existing cold sources are briefly surveyed to determine which materials may be used. Aluminum- and magnesium-based alloys are the preferred materials. Existing data for the effects of cryogenic temperature and near-ambient irradiation on the mechanical properties of these alloys are briefly reviewed, and the very limited information on the effects of cryogenic irradiation are outlined. Generating mechanical property data under cold source operating conditions is a daunting prospect. It is clear that the cold source material will be degraded by neutron irradiation, and so the cold source must be designed as a brittle vessel. The continued effective operation of many different cold ...

International Nuclear Information System (INIS)

To respond to an increase of social problems concerning orphan sources in Japan, a working group was formed in the Japan Health Physics Society. In this working group, we investigated how to prevent acute radiation hazard or social panic regarding orphan sources in scrap metal and detection system for orphan sources brought into scrap yards before recycle. For detection system in a scrap yard we conducted an experiment on detectability of monitoring instrument using a radiation source mixed in scrap metal on a truck. The result showed that it was not easy to detect even a high-level source if it was shielded by scrap metal. We also estimated detection limits for radioactive materials in scrap metal by calculation that was validated with experimental data. We summarized present status about orphan sources in Japan and proposed a categorization of orphan ...

Energy Technology Data Exchange (ETDEWEB)

Background. In multiple myeloma 5 different infiltration patterns can be differentiated: 1. Normal appearance of bone marrow, 2. focal involvement, 3. homogeneous diffuse infiltration, 4. combined diffuse and focal infiltration, 5. 'salt-and pepper' pattern with inhomogeneous bone marrow with interposition of fat islands. Methods. For the fast and total acquisition of all patterns a combination of a T1-weighted spin echo sequence and a fat suppression technique is superior. The focal involvement is clearly demonstrated as areas of high signal intensity on e.g. STIR images. Diffuse involvement can be quantified objectively by calculation of the percentage of signal intensity increase after contrast material injection. MRI is superior to X-ray in focal and diffuse involvement. With ultrafast sequences a 'screening' of the whole red bone marrow as for myeloma infiltration is possible. Prognosis. In prognosis studies diffuse ...

Science.gov (United States)

The choice of treatment in adult skeletal Class III occlusions often poses a particularly tricky problem for the orthodontist. Faced with the option of either orthodontic camouflage or orthognathic surgery, the clinician's clinical experience is of paramount importance, especially in borderline cases. The aim of our study was to uncover a guide model enabling the practitioner to distinguish between skeletal Class III cases which can be suitably treated with orthodontics and those requiring orthognathic surgery. The lateral headfilms of 47 adult patients exhibiting skeletal Class III occlusions were analyzed. The orthodontic group comprised 22 patients and the surgical group 25. Twenty-seven linear, proportional and angular measurements were scrutinized. Stepwise discriminant analysis was used to identify the dentoskeletal and esthetic variables which most distinguished the two groups. The Holdaway angle was chosen to differentiate between patients prior to ...

International Nuclear Information System (INIS)

We present 14 years of contemporaneous photometric and spectroscopic observations of 28 solar analog stars, taken with the Tennessee State University Automatic Photometric Telescopes at Fairborn Observatory and the Solar-Stellar Spectrograph at Lowell Observatory. These are the best observed and most nearly Sun-like of the targets in our magnitude-limited (V #<=# 7.5) sample. The correlations between luminosity and activity reveal the expected inverse activity-brightness correlations for active stars. Strong direct correlations between activity and brightness are not prevalent for the less active solar age stars, but are precision limited. The Sun does not appear to have unusually low photometric variability when compared with the most Sun-like inactive solar analogs. We present evidence that the activity index R'_H_K is not a good discriminant of Maunder Minimum candidate stars. On the basis of a star that appears to have transitioned from a low-variability ...

International Nuclear Information System (INIS)

The nuclide "2"4"1Am decays by alpha emission to "2"3"7Np. Most of the decays (84.6%) populate the excited level of "2"3"7Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of "2"4"1Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid scintillation counting using the logical sum of double coincidences in a TDCR array and defined solid angle counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.

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A scintimetric study using Tc-99m MDP was made of 54 patients with delayed union, nonunion, or late segmental collapse of the femoral head, 4-92 months after femoral neck fracture. In radiographically verified collapse, the radionuclide uptake ratio between the femoral head on the fractured and on the intact side (HHR) was significantly higher than in fractures resulting in delayed union or nonunion. On the basis of scintimetric and radiographic findings, the patients with healing disturbances could be divided into three groups, characterized by the following features: (1) Satisfactory post-reduction position of the fracture without subsequent redisplacement and a high HHR, which as a rule turned out to be delayed union; (2) The same radiographic pattern but with a lower HHR, which in most cases resulted in nonunion; (3) Inadequate reduction or early redisplacement of the fracture with a high HHR, which resulted in nonunion. The fractional precision in ...

CERN Document Server

High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide (NaI(Tl)) and hyperpure germanium as gamma spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g. 2% (at) 662keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse risetimes, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic risetime compensation methods. A two-electrode cylindrical high pressure xenon gamma detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise time of deposited gamma photons. Time ...

CERN Document Server

We present a phenomenological analysis of the recent Tevatron results on the $t \\bar t$ forward-backward asymmetry and invariant-mass spectrum assuming a new contribution from an s-channel gluon resonance with a mass in the range from 700 to 2500 GeV. In contrast to most of the previous works, this analysis shows that for masses below ~1 TeV resonant New Physics could accommodate the experimental data. In general, we find that axial-like couplings are preferred for light and top quark couplings, and that only top quark couples strongly to New Physics. We find that composite model scenarios arise naturally from only phenomenological analyses of the experimental results. We show that our results are compatible with recent LHC limits in dijet and $t \\bar t$ production, and find some tension for large resonance mass ~2.5 TeV. We indicate as best observables for discriminating a relatively light new gluon a better resolution in CDF forward-backward asymmetry, as well ...

CERN Document Server

The presented results are the first measurements at RHIC for direct $\\gamma$-charged hadron azimuthal correlations in heavy ion collisions. We use these correlations to study the color charge density of the medium through the medium-induced modification of high-p$_T$ parton fragmentation. Azimuthal correlations of direct photons at high transverse energy (8 $<$ p$_T$ $<$ 16 GeV) with away-side charged hadrons of transverse momentum (3 $<$ p$_T$ $<$ 6 GeV/c) have been measured over a broad range of centrality for $Au+Au$ collisions and $p+p$ collisions at $\\sqrt{s_{NN}}$ = 200 GeV in the STAR experiment. A transverse shower shape analysis in the STAR Barrel Electromagnetic Calorimeter Shower Maximum Detector is used to discriminate between the direct photons and photons from the decays of high p$_T$ $\\pi^{0}$. The per-trigger away-side yield of direct $\\gamma$ is smaller than from $\\pi^{0}$ trigger at the same centrality class. Within the current ...

International Nuclear Information System (INIS)

In this study, a miniature fiber-optic radiation detector has been developed using a water-equivalent organic scintillator for electron beam therapy dosimetry. Usually, two kinds of light signals such as fluorescent and Cherenkov lights are generated in a fiber-optic radiation detector when a high-energy electron beam is irradiated. The fluorescent light signal is produced in the scintillator and is transmitted through a plastic optical fiber to a remote light-measuring device such as a PMT or a photodiode. The Cherenkov light could be also produced in the plastic optical fiber itself and be detected by a light-measuring device. Therefore, it could cause problems or limit the accuracy of the detection of a fluorescent light signal that is proportional to dose. The objectives of this study are to measure, characterize and eliminate Cherenkov light generated in a plastic optical fiber used as a component of a fiber-optic radiation detector and to detect a real fluorescent light signal ...

CERN Document Server

A complete macromolecule modeling package must be able to solve the simplest structure prediction problems. Despite recent successes in high resolution structure modeling and design, the Rosetta software suite fares poorly on deceptively small protein and RNA puzzles, some as small as four residues. To illustrate these problems, this manuscript presents extensive Rosetta results for four well-defined test cases: the 20-residue mini-protein Trp cage, an even smaller disulfide-stabilized conotoxin, the reactive loop of a serine protease inhibitor, and a UUCG RNA tetraloop. In contrast to previous Rosetta studies, several lines of evidence indicate that conformational sampling is not the major bottleneck in modeling these small systems. Instead, approximations and omissions in the Rosetta all-atom energy function currently preclude discriminating experimentally observed conformations from de novo models at atomic resolution. These molecular "puzzles" should serve as ...

Energy Technology Data Exchange (ETDEWEB)

Manned-space missions bring an exposure due to corpuscular radiations of which nature is quite different from what we encounter in the ground environment. In the space environment, many secondaries are produced through interactions of cosmic ray primaries with the spacecraft wall and other surrounding materials. Among this large variety of radiation components in the space, the contribution of neutrons to the radiation exposure of astronauts has remained to be studied. Up to today, efforts to measure neutron dose equivalent have been made using passive detector systems. Considering uncertainties involved in current measurements and estimations of high energy neutrons, and their increasing importance for future manned missions, it is necessary to measure neutron spectrum in the spacecraft under realistic conditions. The neutron spectra have never been measured on board a spacecraft, because the neutron measurement requires to discriminate between the neutron events ...

Science.gov (United States)

This work investigates the potential use of simultaneously near-infrared (NIR) and mid-infrared (MIR) spectroscopies for the quantitative analysis of fatty acids and triacylglycerols and for identifying the Registered Designation of Origin (RDO) of extra virgin olive oils. The two spectral ranges were used separately using PLS and PLS-DA regressions. To combine both information, concatenated matrix was used at the first time, multiblock method using H-PLS models were constructed at the second time. The models were compared in terms of prediction errors. The results obtained with MIR spectroscopy are better than the ones obtained with NIR spectroscopy. The H-PLS methodology seems to be very interesting for quantitative analysis with the use of additional information in the NIR range, which is not present in the MIR one. For RDO identification by discriminant analysis, the use of multiblock method was less efficient. PMID:20433960

Science.gov (United States)

Examination of measurement invariance provides a powerful method to evaluate the hypothesis that the same set of psychological constructs underlies a set of test scores in different populations. If measurement invariance is observed, then the same psychological meaning can be ascribed to scores in both populations. In this study, the measurement model including core and supplementary subtests of the Wechsler Adult Intelligence Scale-Fourth edition (WAIS-IV) were compared across the U.S. and Canadian standardization samples. Populations were compared on the 15 subtest version of the test in people aged 70 and younger and on the 12 subtest version in people aged 70 or older. Results indicated that a slightly modified version of the four-factor model reported in the WAIS-IV technical manual provided the best fit in both populations and in both age groups. The null hypothesis of measurement invariance across populations was not rejected, and the results provide direct evidence for the ...

International Nuclear Information System (INIS)

A case study is presented where an integrated, ecologically relevant exposure assessment is presented for a polluted lowland river. Using partial least squares regression of latent structures (PLS), an analysis of the impact of two effluents on physico-chemical water quality measures, macroinvertebrate and diatom communities, and in situ bioassay responses with four different test species are combined into an integrative exposure assessment. Bioassays focussed on growth and condition related endpoints, because they are key functional processes of organisms and populations. Integrating these multiple lines of evidence, we were able to discriminate among the impact of both effluents, link changes in physico-chemical water quality with bioassay endpoints and ecological quality of the ecosystem, and address the importance of integrating all information into one exposure assessment framework. The bioassays under field conditions indicated that most endpoints measured ...

CERN Document Server

If gamma-ray bursts originate in galaxies at cosmological distances, the host galaxy should be detected if a burst error box is searched deep enough; are the host galaxies present? We present and implement a statistical methodology which evaluates whether the observed galaxy detections in a burst's error box are consistent with the presence of the host galaxy, or whether all the detections can be attributed to unrelated background galaxies. This methodology requires the model-dependent distribution of host galaxy fluxes. While our methodology was derived for galaxies in burst error boxes, it can be applied to other candidate host objects (e.g., active galaxies) and to other types of error boxes. As examples, we apply this methodology to two published studies of burst error boxes. We find that the nine error boxes observed by Larson and McLean (1997) are too large to discriminate between the presence or absence of host galaxies, while the absence of bright galaxies ...

UK PubMed Central (United Kingdom)

Behavioral detection of a low-frequency (40 Hz) vibratory dipole at source distances of 1.5–24 cm was measured by classically conditioned respiratory suppression in goldfish (Carassius...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Taking the development of large current, negative ion sources which is in progress aiming at nuclear fusion reactors and the development of high luminance ion sources planned as a part of the Omega Project as the examples, the technology for generating high power ion beams is explained. Both these projects are positioned at the limit of the present technology of high power ion beam application as their targeted beam power reaches several tens MW. Consequently, the requirement for the ion sources is severe, and in particular, the generation of the ion beams having large current density with good convergence is beyond all precedents. The application of high power ion sources has been realized as the neutral beam injectors for large tokamaks. Also the hydrogen negative ion source of large current and the electrostatic acceleration technology for negative ion beams have been developed. ...

Energy Technology Data Exchange (ETDEWEB)

The Holifield Radioactive Ion Beam Facility (HRIBF) now under construction at the Oak Ridge National Laboratory will use the 25-MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility; the choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. A high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the HRIBF because of its low emittance, relatively high ionization efficiencies and ...

UK PubMed Central (United Kingdom)

Convolutive mixtures of signals, which are common in acoustic environments, can be difficult to separate into their component sources. Here we present a uniform probabilistic framework to separate...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Recent organic geochemical studies differ radically in their interpretation of the origin of the Gulf coast oils. However all studies since (and including) Thompson, et al. 1989, emphasize the considerable geographic variation in genetic oil types and are in generalized agreement as to the genetic oil types present and their spatial and stratigraphic relationships. In particular it is accepted that the Gulf rim (both north and south) is encircled by a ring of Mesozoic carbonate-sourced oils and that there is also at least one major deep water trend of carbonate-sourced oils in the northern Gulf. It is also generally agreed that many of the Gulf rim oils are of Oxfordian-Kimmeridgian age, though some, like the Sunniland oils of Florida, are of lower Cretaceous origin. Major disagreement still occurs over the sources of the Louisiana offshore oils and onshore Wilcox reservoired oils. One {open_quotes}school of ...

UK PubMed Central (United Kingdom)

Cultural monitoring was used to determine the incidence and sources of salmonellae in a 4160-bird broiler flock raised on litter in 32 pens. Twenty-five of the pens remained apparently free of salmonellae...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundBlood spots collected onto filter paper are an established and convenient source of antibodies for serological diagnosis and epidemiological surveys. Although recommendations...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The polarization of extracted SATURNE II proton beam as a function of different ion source configurations was studied. Two distinct experiments were necessary for this purpose. In the first one, the left-right instrumental asymmetry of the beam polarimeter was determined using an unpolarized beam. In the second one this correction factor was applied to asymmetries measured with the beam from the polarized ion source in all polarization states. The measurements were carried out at the proton beam kinetic energy 0.80 GeV, where the pp-elastic scattering analyzing power is near its maximum. The results confirmed that the two so-called ``unpolarized states`` of the source were polarized to several percent, whereas the absolute values of the beam polarizations in the so-called ``polarized states`` were equal and opposite. It was observed that the hexapole lens of the ion source produced beam polarization in ...

Science.gov (United States)

This table contains point-source catalogs for the ~2 Ms exposure of the Chandra Deep ... Source positions are determined using centroid and matched-filter techniques; .... The 1-sigma upper statistical error (Gehrels 1986, ApJ, 303, ...

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...identity of a confidential source and, in the case of...lawful national security intelligence investigation, confidential...only by the confidential source, (v) Disclose investigative...exercise its authority to open to public observation...requires that the meeting be...

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... The Taiwanese business community is inter- ested in developing access to potential markets as well as to sources of raw materials and some ...

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... by the Bureau. A canvas of supply sources produced only one other, the Flexo roller bearing swivel. Accordingly, only the ...

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Featured Collections Featured collections are information sources that use federated search or are known for presenting exceptional, authoritative information for...

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... range 01-10 nuclei photons radiation sources recoils resonance scattering

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... For the P-wave test, the seismic source was an exploding bridgewire (EBW) detonator which was sufficiently strong in energy ...

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Negative ion based neutral beam injector is one of the most attractive heating system in future fusion reactors. In realizing the system, the crucial device which has to be developed is a high intensity negative ion source. Significant progress has been made on the negative ion source in these years. Among them, a few ampere negative ion beam were produced stably, while the divergence of negative ion beams becomes to be as low as < 10 mrad. We consider these results are demonstrating the potential of the negative ion source for the heating device in future reactors.

International Nuclear Information System (INIS)

Source-term codes to predict the release of radionuclides from nuclear waste packages have been developed and implemented worldwide. A survey and initial comparison of the attributes and capabilities of 13 international source-term codes was recently completed. This preliminary analysis focused on comparison of transport factors/processes and solution methods. This initial comparison is a necessary first step in a properly-conceived, systematic benchmarking of source-term codes. Advantages of such a comparison include assurance of the mathematical correctness of implemented models, comparison and quantification of variances introduced by different types of simplifications, and identification and quantification of the impact of near-field processes.

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There are 13 Electron Beam Ion Sources in operation which produce highly charged ions, up to Th[sup 80+] and Xe[sup 53+]. Most of the sources are used to study these ions under electron impact or when recombining with gaseous or solid targets. That provides an insight into the atomic physics of these highly charged ions and into the physics of the plasma in which such ions can be found. This paper reviews the present knowledge of atomic processes, important in the production of such ions with an EBIS.

International Nuclear Information System (INIS)

The current status and future plans of the Ok Ridge Spallation Neutron Source (ORSNS) are reviewed. The ORSNS is a new project initiated by the U.S. Department of Energy (DOE) beginning October 1, 1995, to prepare the conceptual for a new spallation neutron source. (author) 2 refs.

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Results are described of the study of the analytical applicability of a highly efficient ion source developed for a mass spectrometer. Its ionizer is in the form of a partially closed cavity with a small aperture for leading out ions, heated to a high temperature. The new ion source increases the sensitivity of the apparatus in operations with transuranium elements by almost two orders of magnitude. It is possible to perform isotopic analyses with a high salt content in the sample, and to study the characteristics of nuclear fuel, even without chemical separation of the sample elements.

International Nuclear Information System (INIS)

In conveyor type irradiators, the movement of conveyor and the product boxes is not there until the source is fully in the irradiation position. In case the conveyor system fails the source must automatically be returned to its shielded storage vault. The dose received by the product during the movement of the source from or to the shield becomes significant if the total dose to be received by the product is small. A study has been carried out for evaluating the transient dose received by onions in the POTON irradiator. The results of the study are discussed in this paper. (author)

Science.gov (United States)

This document presents the findings of a study of the Ink Manufacturing Industry for the purpose of developing effluent limitations and standards, and pretreatment standards for existing and new sources to implement Sections 301, 304, 306, 307 and 501 of ...

Energy Technology Data Exchange (ETDEWEB)

A new, magnetically insulated negative ion source has recently been discovered which can produce pulsed negative ion beams (H/sup -/, Li/sup -/, and C/sup -/) with intensities of 100-300 A/cm/sup 2/ at 1-4 MeV. This source may provide the basis for a high energy neutral beam system for heating large tokamaks.

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Glasses in the system (95-x) [0.25 Na{sub 2}O-0.75 B{sub 2}O{sub 3}]-x P{sub 2}O{sub 5}-5 Fe{sub 2}O{sub 3} (0<=x<=15 mol%), have been prepared by the melt quenching technique. Elastic properties and FT-IR spectroscopic studies have been employed to study the role of P{sub 2}O{sub 5} on the structure of the glass system. Elastic properties Poisson's ratio, micro-hardness and Debye temperature have been investigated using sound wave velocity measurements at 4 MHz (both longitudinal and shear) at room temperature. The results showed that the density and the molar volume increase as both sound velocities and the determined glass transition temperatures decrease with increasing the contents of P{sub 2}O{sub 5}. Infrared spectra of the glasses reveal that the borate network consists of diborate units and is affected by the increase in the concentration of P{sub 2}O{sub 5} content as a second network former. These results are interpreted in terms of the replacement of ...

International Nuclear Information System (INIS)

Magnetic resonance (MR) imaging was performed in 26 patients with Ewing's sarcoma of bone preceding and following neoadjuvant chemotherapy, to assess tumour response non-invasively prior to surgery. T1- and T2-weighted spin echo images were obtained. Changes including intra- and extramedullary signal intensities, tumour demarcation, tumour volume and the appearance of residual extramedullary tumour were compared with histophathology of the resected specimens. Reduction of tumour volume was significantly higher in good responders. Other single parameters did not correlated with histologic tumour response. However, when several MR parameters summarized in a classification system were combined, a positive correlation with histopathologic response was found. A limited decrease of tumour volume (<25 %) and/or residual soft tissue mass following chemotherapy correlated with a poor response. An inhomogeneous, well-defined cuff of abnormal tissue encircling the bone ...

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56 patients with the clinical diagnosis of sprained ankles were investigated. Evaluation of the anterior (AFTL) and posterior fibulotalar ligament (PFTL) was performed with the foot in dorsiflexion (20 ) and of the fibulo calcanear ligament (FCL) in plantarflexion (45 ). Axial T{sub 1}w-SE and T{sub 2}w-TSE images were obtained. Full-length visualisation of ligmaments in one slice and the extent of injury were evaluated. 12 ankle injuries were confirmed by operation. With MRI full-length visualisation of lateral ankle ligaments was possible in 86%. A partial/complete rupture of the AFTL was noticed in 33/64% and of the FCI in 29/39%, and of the PFTL in 27/5%. Sensitivity/specificity of MRI when compared to surgery was 100/100% for injuries of the AFTL, 64/100% for the FCL, and 33/78% for the PFTL. (orig./MG) [Deutsch] 56 Patienten wurden mit der klinischen Diagnose einer frischen Supinationsverletzung des oberen Sprunggelenkes untersucht. Das Lig. talofibulare anterius (TFA) und ...

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The evaluation of possible manufacture-based defects in turbine shafts and housings for component serviceability relevance is of particular interest not only in post-manufacturing NDT but also in evaluation of NDT results obtained by in-service inspections of components with long service lives. The results discussed in the paper are summarized as follows: Most of the examined natural defects in the forgings and castings behave like cracks under the simulated operating conditions and hence may well be evaluated by fracture mechanical methods for their serviceability relevance determined by crack propagation under fatigue, creep and creep-fatigue stress. The empirical correlation of true defect size and US testing results (echo signal, echodynamics, attenuation) permits improved determination of true defect sizes in the turbine components. Care has to be taken to select the proper testing and evaluation methods in compliance with defect types. (orig./MM) [Deutsch] ...

International Nuclear Information System (INIS)

Forty-four patients with small cell carcinoma of the bronchus underwent CT and MR studies of the brain to detect cerebral metastases. All patients were studied with contrast-enhanced CT scans, short (T1-weighted) and long (T2-weighted), spin-echo (SE) and FLASH 90 grades sequences were also obtained. A quantitative comparison of the results was carried out to assess the sensitivity of the different techniques in the detection of brain metastases according to lesion diameter. Metastases were identified in 19/44 patients (43%). All techniques detected the lesions >2 cm; of the metastases <2 cm, 63/124 (51%) were detected only by GdDTPA SE-T1 and FLASH sequences and 11 more (9%) only by Gd-DTPA SE-T1 scans. All the lesions identified oh enhanced CT scans or on T2-weighted images were easily detected by Gd-DTPA scans. CT sensitivity was higher than that of pre-contrast SE-T1 and FLASH studies and only slightly lower than that of T2-weighted images. As for lesions ...

International Nuclear Information System (INIS)

This report seeks to address the role of hydrogen bonding with Bronsted acids and bases in proton-coupled electron transfer (PCET) as it pertains to concerted or stepwise pathways of quinone (Q) and hydroquinone (QH_2) electrochemistry. This study was performed using a series of techniques that included cyclic voltammetry (CV), digital simulations, computational chemistry and "1H NMR. Hydrogen bonding was inferred by a decrease in diffusion coefficient (D) values measured using a pulsed gradient echo- (PGE-) "1H NMR technique. Changes of 40.8% and 37.9% in D values were only noted after the addition of two equivalents of acetate to 1,4-hydroquinone (1,4-QH_2) and catechol (1,2-QH_2), respectively. In contrast, the D values for the addition of selected amines (pyridine, N,N-diisopropylethylamine and triethylamine) changed only 3.2% on average. Quantum mechanical calculations were conducted to determine the pK_a of all quinoid species to serve as a starting point for ...

CERN Document Server

We observed at 22 GHz with the VLBI array VERA a sample of 1536 sources with correlated flux densities brighter than 200 mJy at 8 GHz. One half of target sources has been detected. The detection limit was around 200 mJy. We derived the correlated flux densities of 877 detected sources in three ranges of projected baseline lengths. The objective of these observations was to determine the suitability of given sources as phase calibrators for dual-beam and phase-referencing observations at high frequencies. Preliminary results indicate that the number of compact extragalactic sources at 22 GHz brighter than a given correlated flux density level is twice less than at 8 GHz.

International Nuclear Information System (INIS)

Despite the widely recognized usefulness of the AAPM TG-43 brachytherapy dose calculation formalism, a straightforward application of this approach to describe the dose distribution about intravascular line sources as proposed by TG-60 may be difficult or even impossible, especially when these line sources emit low-energy photons or beta particles. The causes of these limitations are investigated and illustrated by means of some numerical examples. In order to solve the observed limitations an adapted formalism is proposed, intended specifically for the description of the dose rate distribution about line sources but conceptually similar to the TG-43/TG-60 formalism. Several examples are presented to illustrate the usefulness of the proposed line source dose calculation formalism.

CERN Document Server

Consider the set of source distributions within a fixed maximum relative entropy with respect to a given nominal distribution. Lossless source coding over this relative entropy ball can be approached in more than one way. A problem previously considered is finding a minimax average length source code. The minimizing players are the codeword lengths --- real numbers for arithmetic codes, integers for prefix codes --- while the maximizing players are the uncertain source distributions. Another traditional minimizing objective is the first one considered here, maximum (average) redundancy. This problem reduces to an extension of an exponential Huffman objective treated in the literature but heretofore without direct practical application. In addition to these, this paper examines the related problem of maximal minimax pointwise redundancy and the problem considered by Gawrychowski and Gagie, which, for a ...

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The Holifield Radioactive Ion Beam Facility now under construction at the Oak Ridge National Laboratory will use the 25 MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility. The choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. Although direct-extraction negative ion sources are clearly desirable, the ion formation efficiencies are often too low for practical consideration; for this situation, positive ion sources, in combination with charge exchange, are the logical choice. The ...

CERN Document Server

XMM-Newton EPIC observations reveal the population of X-ray sources of the bright Local Group spiral galaxy M 31, a low-star-formation-rate galaxy like the Milky Way, down to a 0.2-4.5 keV luminosity of 4.4E34 erg/s. With the help of X-ray hardness ratios and optical and radio information different source classes can be distinguished. The survey detected 856 sources in an area of 1.24 square degrees. Sources within M 31 are 44 supernova remnants (SNR) and candidates, 18 super-soft sources (SSS), 16 X-ray binaries (XRBs) and candidates, as well as 37 globular cluster sources (GlC) and candidates, i.e. most likely low mass XRBs within the GlC. 567 hard sources may either be XRBs or Crab-like SNRs in M 31 or background AGN. 22 sources are new SNR candidates in M 31 based on X-ray selection criteria. Time variability ...

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Electron cyclotron resonance (ECR) ion sources possess several advantages over ion sources conventionally used for injectors of electrostatic accelerators: improved reliability, high efficiency, simplicity, and the capability of generating bright, high-current ion beams. We have adapted a high-current ECR source originally developed as an injector for a CW RFQ proton linac to serve as a source of intense negative-ion beams for the Tandem Accelerator Superconducting Cyclotron (TASCC) facility at Chalk River. The range of ion species of the source has been extended from H{sup 1+} alone up to Bi{sup 1+}, with both gaseous and nonvolatile feeds. Two intense negative-ion beams of He{sup -} and O{sup -} have been generated so far with the source coupled to a standard charge-exchange canal. We foresee no major problems generating a broad range of negative ions with ...

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The flux of cosmic ray antiprotons with kinetic energies between /approximately/1 and 15 GeV is /approximately/5 times greater than the flux predicted on the basis of the leaky-box model. This excess is attributed to secondary antineutron production in compact sources. Because the antineutrons are not confined by the magnetic field of the compact source, they leave the interaction site, decay in interstellar space and account for the apparent excess cosmic ray antiproton flux. The escape and decay of neutrons produced in association with the antineutrons is a source of cosmic ray protons. Observations of the angular variation of the intensity and spectral shape of 100 MeV ..gamma..-rays produced by neutron-decay protons in the reaction p + p ..-->.. ..pi../sup 0/ ..-->.. 2..gamma.. could reveal compact-source cosmic ray production sites. COS-B observations of spectral hardening near point ...

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A versatile, high brightness, volume type, low power RF source, capable of producing positive ion beams with intensities as high as 1 mA from gaseous feed materials and microamperes of negative ion beams has been characterized. The source can also be operated as a plasma sputter negative ion source to generate up to 1 mA of a selected species. The performance of the source in the positive and negative volume modes of operation can be greatly enhanced by addition of a removable, water cooled filament assembly in place of the negative sputter probe. For examine, the material utilization efficiencies of gaseous feed species can be more than doubled, total current intensities increased up to 40%, molecular dissociation fractions increased by 20% and minimum operating pressures reduced by a factor of four when operated in the volume mode. These added electrons also favorably effect, as a consequence of lower ...

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Recent analyses of the anisotropy of cosmic rays at 10{sup 18} eV (the AGASA and SUGAR data) show significant excesses from regions close to the galactic centre and Cygnus. Our aim is to check whether such anisotropies can be caused by single sources of charged particles. We investigate propagation of protons in two models of the galactic regular magnetic field (with the irregular component included) assuming that the particles are injected by a short-lived discrete source lying in the direction of the galactic centre. We show that apart from a prompt image of the source, the regular magnetic field may cause delayed images at quite large angular distances from the actual source direction. The image is strongly dependent on the time elapsed after ejection of particles and it is also very sensitive to their energy. For the most favourable conditions for particle acceleration by a young pulsar, the ...

CERN Document Server

Volume sources is used for standard sources by radioactive measurement using Ge semiconductor detector of environmental sample, e.g. water, soil and etc. that require large volume. The commercial volume source used in measurement of the water sample is made of agar-agar, and that used in measurement of the soil sample is made of alumina powder. When the plastic receptacles of this two kinds of volume sources were damaged, the leakage contents cause contamination. Moreover, if hermetically sealing performance of volume source made of agar-agar fell, volume decrease due to an evaporation off moisture gives an error to radioactive measurement. Therefore, we developed the two type methods using unsaturated polyester resin, vinilester resin, their hardening agent and acrylicresin. The first type is due to dispersing the hydrochloric acid solution included the radioisotopes uniformly in ...

International Nuclear Information System (INIS)

We present a development of the use of the AAPM TG-43 dose formalism applied to "1"3"7Cs gynecological implant sources. The geometry factor, radial dose function, and anisotropy function of a "1"3"7Cs source modeled after the Nuclear Associates 67-809 series stainless steel jacketed tube source were derived following the AAPM TG-43 formalism. The dose rate distribution through the center of the source using the AAPM TG-43 dose formalism is calculated and compared with the calculations obtained using the Sievert summation and Monte Carlo simulation. The three methods resulted in an agreement within less than 5%, or an isodose rate line agreement within 2 mm. We demonstrate that the AAPM TG-43 formalism can be applied to "1"3"7Cs linear sources and is capable of serving as a "1"3"7Cs dose calculation algorithm that can be used for treatment planning purpose.

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A multicusp magnetic field plasma surface ion source, normally used for H/sup /minus//ion beam formation, has been modified for the generation of high-intensity, pulsed, heavy negative ion beams suitable for a variety of uses. To date, the source has been utilized to produce mA intensity pulsed beams of more than 24 species. A brief description of the source, and basic pulsed-mode operational data, (e.g., intensity versus cesium oven temperature, sputter probe voltage, and discharge pressure), are given. In addition, illustrative examples of intensity versus time and the mass distributions of ion beams extracted from a number of samples along with emittance data, are also presented. Preliminary results obtained during dc operation of the source under low discharge power conditions suggest that sources of this type may also be used to produce high-intensity (mA) dc beams. The results ...

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Aim: Today, MRI is an integral part of the presurgical evaluation of patients suffering from partial epilepsy. These patients frequently show focal morphological abnormalities with potential epileptogenic character and surgical resection of these lesions is associated with superior postsurgical outcome as to seizure frequency. Apart from easily detectable defects, such as post-traumatic lesions or cerebral infarction, as wide variety of mainly small abnormalities can be detected using MRI. Methods: In this study, 484 patients suffering from partial epilepsy of temporal or frontal onset were evaluated for the incidence of different lesions in this population. Results: All lesions found were included without evaluating their potential epileptogenicity, which remains to be proven using other procedures (EEG, SPECT, PET, etc.). Involvement of the hippocampal formation was a major finding in temporal lobe epilepsy, which could be detected as sclerosis (T2w-images), atrophy (T2w-TSE or ...

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Considering the hardware characteristics of the laser-induced plasma X-ray source and the limitations of the conventional cone-beam reconstruction algorithm, a general cone-beam reconstruction algorithm has been developed at our laboratory, in which the motion locus of the X-ray source is an arbitrary curve corresponding to at least a 2{pi} continuous horizontal angular displacement in the coordinate system of the specimen. The preliminary simulation shows that the general cone-beam reconstruction algorithm consistently results in visually satisfactory images.

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Ammonia gas (NH{sub 3}) has been used as a nitrogen source for plasma source ion implantation processing of electroplated chromium. No evidence was found of increased hydrogen concentrations in the bulk material, implying that ammonia can be used without risking hydrogen embrittlement. The retained nitrogen dose of 2.1 {times} 10{sup 17} N-at/cm{sup 2} is sufficient to increase the surface hardness of electroplated Cr by 24% and decrease the wear rate by a factor of 4.

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This paper presents calculations of the {sup 252}Cf-source-driven noise analysis measurements for subcritical highly enriched uranium metal cylinders using the Monte Carlo code MCNP-DSP. This code directly calculates the noise analysis data from the {sup 252}Cf- source-driven noise analysis method for both neutron and gamma ray detectors. Direct calculation of experimental observables by the Monte Carlo method allows for the benchmarking of the calculational model and the cross sections and for determining the bias in the calculation.

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Average emittance data for ion beams extracted from cesium-sputter negative ion sources equipped with spherical, ellipsoidal, and cylindrical geometry cesium-surface ionizers are presented. The attributes of the respective source geometries are described in terms of their cesium ion optical properties. The results of recent measurement of the emittances of momentum-analyzed beams extracted from the ellipsoidal geometry source are also presented. These measurements indicate the presence of a species-dependent effect. The effect is believed to be attributable to differences in the energy spreads of the respective negative ion beams introduced by the sputter generation process. 11 refs., 8 figs.