scholarly journals Spectral Tomography for 3D Element Detection and Mineral Analysis

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 598
Author(s):  
Jose R. A. Godinho ◽  
Gabriel Westaway-Heaven ◽  
Marijn A. Boone ◽  
Axel D. Renno
Keyword(s):  
Energy Spectrum ◽  
3D Imaging ◽  
X Rays ◽  
3D Images ◽  
Characterization Methods ◽  
X Ray ◽  
Additional Information ◽  
Mineral Phases ◽  
Spectral Computed Tomography

This paper demonstrates the potential of a new 3D imaging technique, Spectral Computed Tomography (sp-CT), to identify heavy elements inside materials, which can be used to classify mineral phases. The method combines the total X-ray transmission measured by a normal polychromatic X-ray detector, and the transmitted X-ray energy spectrum measured by a detector that discriminates between X-rays with energies of about 1.1 keV resolution. An analysis of the energy spectrum allows to identify sudden changes of transmission at K-edge energies that are specific of each element. The additional information about the elements in a phase improves the classification of mineral phases from grey-scale 3D images that would be otherwise difficult due to artefacts or the lack of contrast between phases. The ability to identify the elements inside the minerals that compose ore particles and rocks is crucial to broaden the application of 3D imaging in Earth sciences research and mineral process engineering, which will represent an important complement to traditional 2D imaging mineral characterization methods. In this paper, the first applications of sp-CT to classify mineral phases are showcased and the limitations and further developments are discussed.

scholarly journals 3D Imaging in Unilateral Primary Pulmonary Hypoplasia in an Adult: A Case Report

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
Aristida Georgescu ◽  
Crinu Nuta ◽  
Simona Bondari
Keyword(s):  
3D Imaging ◽  
Pulmonary Hypoplasia ◽  
Left Lung ◽  
Left Lobe ◽  
X Rays ◽  
X Ray ◽  
Female Smoker ◽  
Multidetector Computer Tomography ◽  
Biological Tests ◽  
Chest X Ray

Unilateral primary pulmonary hypoplasia is rare in adulthood (UPHA); it is characterized by a decreased number of bronchial segmentation and decreased/absent alveolar air space. Classical chest X-ray may be confusing, and the biological tests are unspecific. We present a case of UPHA in a 60-year-old female, smoker, with 3 term normal deliveries, who presented with late recurrent pneumonias and bronchiectasis-type symptomathology, arterial hypertension, and obesity. Chest X-rays revealed opacity in the left lower pulmonary zone, an apparent hypoaerated upper left lobe and left deviation of the mediastinum. Preoperatory multidetector computer tomography (MDCT) presented a small retrocardiac left lung with 5-6 bronchial segmentation range and cystic appearance. After pneumonectomy the gross specimen showed a small lung with multiple bronchiectasis and small cysts, lined by hyperplasic epithelium, surrounded by stromal fibrosclerosis. We concluded that this UPHA occurred in the 4–7 embryonic weeks, and the 3D MDCT reconstructions offered the best noninvasive diagnosis.

Classification of Fresh Fractures of the Lunate

1988 ◽  
Vol 13 (4) ◽  
pp. 458-462
Author(s):  
H. TEISEN ◽  
J. HJARBAEK
Keyword(s):  
Vascular Anatomy ◽  
X Rays ◽  
Lunate Bone ◽  
X Ray

The X-rays of 17 patients with fresh fractures of the lunate bone have been reviewed. The fractures were classified according to their radiological appearances and according to the vascular anatomy of the lunate. A long term X-ray follow-up examination was performed.

Effect of Asymmetry on a Trap Model for Solar Hard Xray Bursts

1979 ◽  
Vol 3 (6) ◽  
pp. 369-371 ◽  
Author(s):  
D. B. Melrose ◽  
S. M. White
Keyword(s):  
Magnetic Flux ◽  
Flux Tube ◽  
Magnetic Trap ◽  
Energetic Particles ◽  
Magnetic Flux Tube ◽  
X Rays ◽  
Radio Observations ◽  
X Ray ◽  
Additional Information ◽  
Basic Model

The basic model for the precipitation of trapped energetic particles from a magnetic flux tube is Kennel and Petschek’s (1966) model. Their model is symmetric, implying equal precipitation rates at the two feet of the flux tube. We have developed a model for precipitation in an asymmetric flux tube (Melrose and White 1979). Here we explore some of the consequences for the precipitation model of Melrose and Brown (1976) for solar hard X-ray bursts. In Melrose and Brown’s model roughly half the X-rays arise from precipitating electrons. With present instruments it is not possible to resolve the two feet of the flux tube. However, if the feet can be resolved, either directly by future X-ray telescopes, or indirectly through secondary optical, UV or radio observations, then, as we shall show, the additional information obtained could be used to derive information on processes in the magnetic trap.

scholarly journals Multilayer Laue Lens: A Path Toward One Nanometer X-Ray Focusing

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Hanfei Yan ◽  
Hyon Chol Kang ◽  
Ray Conley ◽  
Chian Liu ◽  
Albert T. Macrander ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Numerical Aperture ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Diffraction Effect ◽  
X Rays ◽  
Dynamical Diffraction ◽  
Characterization Methods ◽  
X Ray ◽  
Laue Lens

The multilayer Laue lens (MLL) is a novel diffractive optic for hard X-ray nanofocusing, which is fabricated by thin film deposition techniques and takes advantage of the dynamical diffraction effect to achieve a high numerical aperture and efficiency. It overcomes two difficulties encountered in diffractive optics fabrication for focusing hard X-rays: (1) small outmost zone width and (2) high aspect ratio. Here, we will give a review on types, modeling approaches, properties, fabrication, and characterization methods of MLL optics. We show that a full-wave dynamical diffraction theory has been developed to describe the dynamical diffraction property of the MLL and has been employed to design the optimal shapes for nanofocusing. We also show a 16 nm line focus obtained by a partial MLL and several characterization methods. Experimental results show a good agreement with the theoretical calculations. With the continuing development of MLL optics, we believe that an MLL-based hard x-ray microscope with true nanometer resolution is on the horizon.

scholarly journals NuSTAR reveals that the heavily obscured nucleus of NGC 2785 was the contaminant of IRAS 09104+4109 in the BeppoSAX/PDS hard X-rays

2018 ◽  
Vol 619 ◽  
pp. A16
Author(s):  
C. Vignali ◽  
P. Severgnini ◽  
E. Piconcelli ◽  
G. Lanzuisi ◽  
R. Gilli ◽  
...  
Keyword(s):  
X Rays ◽  
X Ray ◽  
Star Forming ◽  
Physical Description ◽  
Enhanced Sensitivity ◽  
X Ray Imaging ◽  
First Time ◽  
In Virtue Of

Context. The search for heavily obscured active galactic nuclei has been revitalized in the last five years by NuSTAR, which has provided a good census and spectral characterization of a population of such objects, mostly at low redshift, thanks to its enhanced sensitivity above 10 keV compared to previous X-ray facilities, and its hard X-ray imaging capabilities. Aims. We aim at demonstrating how NGC 2785, a local (z = 0.009) star-forming galaxy, is responsible, in virtue of its heavily obscured active nucleus, for significant contamination in the non-imaging BeppoSAX/PDS data of the relatively nearby (≈17′) quasar IRAS 09104+4109 (z = 0.44), which was originally mis-classified as Compton thick. Methods. We analyzed ≈71 ks NuSTAR data of NGC 2785 using the MYTorus model and provided a physical description of the X-ray properties of the source for the first time. Results. We found that NGC 2785 hosts a heavily obscured (NH ≈ 3 × 1024 cm−2) nucleus. The intrinsic X-ray luminosity of the source, once corrected for the measured obscuration (L2−10keV ≈ 1042 erg s−1), is consistent within a factor of a few with predictions based on the source mid-infrared flux using widely adopted correlations from the literature. Conclusions. Based on NuSTAR data and previous indications from the Neil Gehrels Swift Observatory (BAT instrument), we confirm that NGC 2785, because of its hard X-ray emission and spectral shape, was responsible for at least one third of the 20–100 keV emission observed using the PDS instrument onboard BeppoSAX, originally completely associated with IRAS 09104+4109. Such emission led to the erroneous classification of this source as a Compton-thick quasar, while it is now recognized as Compton thin.

scholarly journals Simultaneous measurements of X-rays and electrons during a pulsating aurora

1998 ◽  
Vol 16 (2) ◽  
pp. 148-160 ◽  
Author(s):  
N. Østgaard ◽  
J. Stadsnes ◽  
K. Aarsnes ◽  
F. Søraas ◽  
K. Måseide ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Energy Range ◽  
Energetic Particle ◽  
Good Method ◽  
Electron Energy Spectrum ◽  
Electron Precipitation ◽  
X Rays ◽  
X Ray ◽  
Electron Spectra ◽  
Simultaneous Measurements

Abstract. The PULSAUR II rocket was launched from Andøya Rocket Range at 23.43 UT on 9 February 1994 into a pulsating aurora. In this paper we focus on the observations of precipitating electrons and auroral X-rays. By using models it is possible to deduce the electron energy spectrum from X-ray measurements. Comparisons are made between the deduced electron fluxes and the directly measured electron fluxes on the rocket. We found the shape of the observed and the deduced electron spectra to fit very well, with almost identical e-folding energies in the energy range from 10 ke V to ~60–80 ke V. For the integrated fluxes from 10.8 to 250 ke V, we found a discrepancy of 30% . By combining two models, we have found a good method of deducing the electron precipitation from X-ray measurements. The discrepancies between calculations and measurements are in the range of the uncertainties in the measurements.Key words. Ionospheric particle precipitation · Magnetospheric physics · Annual phenomena · Energetic particle

scholarly journals NEEDLE DETECTOR OF X-RAY AND GAMMA RADIATION

2017 ◽  
Vol 7 (1) ◽  
pp. 121-124
Author(s):  
Grzegorz Domański ◽  
Roman Szabatin ◽  
Piotr Brzeski ◽  
Bogumił Konarzewski
Keyword(s):  
Energy Spectrum ◽  
Gamma Radiation ◽  
Gamma Rays ◽  
Proportional Counter ◽  
Incident Radiation ◽  
X Rays ◽  
The Novel ◽  
Direction Parallel ◽  
X Ray ◽  
Gas Detector

The article presents the developed structure of the novel needle proportional gas detector (NPC – Needle Proportional Counter) used for the detection of X-rays and gamma rays. The advantage of the detector is its simple mechanical construction and the possibility of detection of incident radiation in a direction parallel to the needle. The measured energy spectrum of the isotope Fe-55 by means of the developed detector is presented.

scholarly journals COVID-19 detection and disease progression visualization: Deep learning on chest X-rays for classification and coarse localization

2020 ◽  
Author(s):  
Tahmina Zebin ◽  
Shahadate Rezvy ◽  
Wei Pang
Keyword(s):  
Disease Progression ◽  
Detection Accuracy ◽  
X Rays ◽  
Automated Classification ◽  
X Ray ◽  
Feature Extractor ◽  
Chest X Ray ◽  
Activation Mapping ◽  
Activation Map

Abstract Chest X-rays are playing an important role in the testing and diagnosis of COVID-19 disease in the recent pandemic. However, due to the limited amount of labelled medical images, automated classification of these images for positive and negative cases remains the biggest challenge in their reliable use in diagnosis and disease progression. We applied and implemented a transfer learning pipeline for classifying COVID-19 chest X-ray images from two publicly available chest X-ray datasets {https://github.com/ieee8023/covid-chestxray-dataset},{https://www.kaggle.com/paultimothymooney/chest-xray-pneumonia}}. The classifier effectively distinguishes inflammation in lungs due to COVID-19 and pneumonia (viral and bacterial) from the ones with no infection (normal). We have used multiple pre-trained convolutional backbones as the feature extractor and achieved an overall detection accuracy of 91.2% , 95.3%, 96.7% for the VGG16, ResNet50 and EfficientNetB0 backbones respectively. Additionally, we trained a generative adversarial framework (a cycleGAN) to generate and augment the minority COVID-19 class in our approach. For visual explanations and interpretation purposes, we visualized the regions of input that are important for predictions and a gradient class activation mapping (Grad-CAM) technique is used in the pipeline to produce a coarse localization map of the highlighted regions in the image. This activation map can be used to monitor affected lung regions during disease progression and severity stages.

scholarly journals Non-solar gamma and X-ray astronomy: optical observations: (Invited discourse)

1970 ◽  
Vol 37 ◽  
pp. 151-161
Author(s):  
Hugh M. Johnson
Keyword(s):  
Variable Stars ◽  
Optical Observations ◽  
X Rays ◽  
Spectral Measurements ◽  
Optical Identification ◽  
Stellar Spectrum ◽  
X Ray ◽  
General Catalogue ◽  
The Continuum

An optical astronomer enters this field only by courtesy of those X-ray astronomers who pay some attention to accurate positional measurements of X-ray sources. So my first and last words are to ask X-ray observers to give more time to establishing positions of X-ray sources. It appears that in fact most effort has been spent on spectral measurements of X-rays, and this has led just to the classification of sources according to either of two mechanisms for the production of the continuum. In one or two early instances the extrapolated X-ray spectrum has been useful for predicting the brightness of the optical counterpart to be found. A typical uncertainty of making optical identification is that of Vel XR-1 for which Gursky et al. (1968) have given a position with an error box of 3 square degrees. One candidate I can suggest for this is CU Vel, the only variable star of the 1958 General Catalogue of Variable Stars inside the error box. It is interesting because it is assigned to the U Gem class with a range of photographic magnitudes from 10.7 to 15.5. The stellar spectrum has not been observed.

scholarly journals Unveiling the Multi-wavelength Phenomenology of Anomalous X-ray Pulsars

2004 ◽  
Vol 218 ◽  
pp. 247-250 ◽  
Author(s):  
GianLuca Israel ◽  
Luigi Stella ◽  
Stefano Covino ◽  
Sergio Campana ◽  
Lorella Angelini ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Broad Band ◽  
Archival Data ◽  
X Rays ◽  
Spectral Variability ◽  
Band Energy ◽  
X Ray ◽  
Pulse Phase ◽  
Multi Wavelength ◽  
Ir Bands

During 2002–2003 the number of IR-identified counterparts to the Anomalous X-ray Pulsars (AXPs) has grown to four (4U 0142+61, IE 2259+586, IE 1048.1−5937 and RXS J170849−400910) out of the six objects (plus two candidates) known in this class. More importantly, some new common characteristics have been identified, such as IR variability, IR flattening in the broad-band energy spectrum, X-ray spectral variability as a function of pulse phase (which are not predicted by the magnetar model), and X-ray bursts (which cannot be explained in terms of standard accretion models). We present the results obtained from an extensive multi-wavelength observational campaign carried out with the NTT and CFHT for the optical/IR bands, and XMM and Chandra (plus BeppoSAX archival data) in X-rays. Based on these results and those reported in the literature, the IR-to-X-ray emission of AXPs is compared.

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