Magnetic Measurements Over Darnley Bay, N.W.T.

1972 ◽  
Vol 9 (8) ◽  
pp. 972-978 ◽  
Author(s):  
R. P. Riddihough ◽  
G. V. Haines

Five high level, 3-component, magnetic profiles outline a large magnetic anomaly approximately coincident with the previously observed, 130 mgal, positive gravity anomaly. Three-dimensional interpretations of the magnetic data establish the major dimensions of the source body but do not distinguish between a normal and inverted conical shape. Directions of magnetization derived from the interpretations suggest that the body is geologically related to the Precambrian Franklin Diabases.

1981 ◽  
Vol 18 (4) ◽  
pp. 680-692 ◽  
Author(s):  
P. S. Kumarapeli ◽  
A. K. Goodacre ◽  
M. D. Thomas

Prominent, nearly coincident, positive gravity and magnetic anomalies occur in the Sutton Mountains region, centered about 100 km east of Montreal, Quebec. Several lines of evidence indicate that the gravity anomaly stems from two principal sources: a deep (mid and lower crustal) source of speculative origin and a shallow source identifiable with a narrow belt of late Precambrian – early Cambrian metavolcanic rocks, the Tibbit Hill volcanics. The magnetic anomaly seems to be produced mainly by the metavolcanic rocks. Three-dimensional modelling of a residual gravity anomaly, supplemented by two-dimensional modelling of the magnetic anomaly, shows that the seemingly minor belt of metavolcanic rocks constitutes the surface expression of a thick (maximum thickness ~8 km) pile of dominantly mafic volcanics, which are only slightly exposed at the present level of erosion.The Tibbit Hill volcanics are regarded as products of rift-related volcanism that occurred at an rrr triple junction developed during the early stages of the opening of the Iapetus Ocean. The Ottawa graben is probably the failed arm of this triple junction. The emplacement of the Grenville dike swarm whose trend is nearly coincident with that of the Ottawa graben was probably coeval with the volcanism in the Sutton Mountains region. The present work shows that the volcanism in the region was on a much larger scale than hitherto recognized.


2001 ◽  
Vol 674 ◽  
Author(s):  
Chiung-Hsiung Chen ◽  
Ting-Sheng Huang ◽  
Ming-Fong Tai

ABSTRACTIn this study, we used x-ray diffraction patterns and dc magnetic measurements to investigate the crystallographic structure, magnetic properties and scaling behavior of the distorted perovskite La0.7(Ba1−xPbx)0.3CoO3 (0 ≤ x ≤ 0.5) system with a constant ratio of Co4+/Co3+. Samples with x = 0.0 and 0.1 were crystallized in the cubic structure with a ∼ 7.76 Å whereas samples with x ≥ 0.2 were crystallized in an orthorhombic Pbnm space group with a ∼ b ∼ 5.50 Å and c ∼ 7.85 Å. For all our samples the spin-glass-like behavior were observed in low temperature and low field ranges. The Pb2+ substitution on Ba2+ site does not significantly affect the ferromagnetic transition temperature TC, but does introduce large variation in the magnetic strength. In both the ferromagnetic and paramagnetic states the minimum values of the average effective moments provided by every Co ion occur at x = 0.3. We also observed the scaling behaviors of magnetic data in all samples. The derived values of the critical exponents (β, γ, δ) were consistent with those predicted by mean field theory and a three-dimensional Heisenberg model.


2014 ◽  
Vol 1 (4) ◽  
pp. 272-288 ◽  
Author(s):  
Tomotake Furuhata ◽  
Inho Song ◽  
Hong Zhang ◽  
Yoed Rabin ◽  
Kenji Shimada

Abstract This paper presents a two-step, semi-automated method for reconstructing a three-dimensional (3D) shape of the prostate from a 3D transrectal ultrasound (TRUS) image. While the method has been developed for prostate ultrasound imaging, it can potentially be applicable to any other organ of the body and other imaging modalities. The proposed method takes as input a 3D TRUS image and generates a watertight 3D surface model of the prostate. In the first step, the system lets the user visualize and navigate through the input volumetric image by displaying cross sectional views oriented in arbitrary directions. The user then draws partial/full contours on selected cross sectional views. In the second step, the method automatically generates a watertight 3D surface of the prostate by fitting a deformable spherical template to the set of user-specified contours. Since the method allows the user to select the best cross-sectional directions and draw only clearly recognizable partial or full contours, the user can avoid time-consuming and inaccurate guesswork on where prostate contours are located. By avoiding the usage of noisy, incomprehensible portions of the TRUS image, the proposed method yields more accurate prostate shapes than conventional methods that demand complete cross-sectional contours selected manually, or automatically using an image processing tool. Our experiments confirmed that a 3D watertight surface of the prostate can be generated within five minutes even from a volumetric image with a high level of speckles and shadow noises.


2019 ◽  
Vol 41 (1) ◽  
pp. 69-80
Author(s):  
Nguyen Thi Thu Hang ◽  
Erdinc Oksum ◽  
Le Huy Minh ◽  
Do Duc Thanh

The paper presents an improved algorithm based on Bhaskara Rao and Ramesh Babu’s algorithm to invert magnetic anomalies of three-dimensional basement structures. The magnetic basement is approximated by an ensemble of juxtaposed vertical prisms whose bottom surface coincides with Curie surface with the known depth. The computer program operating with the proposed algorithm is built in Matlab environment. Test applications show that the proposed method can perform computations with fast and stable convergence rate where the results also coincide well with the actual model structure. The effectiveness of the method is demonstrated by inverting magnetic anomalies of the southeast part of Vietnam continental shelf. The calculated magnetic basement relief of the study area provides useful additional information for studies in the aim of dealing with the geological structure of the area.References Beiki M., 2010. Analytic signals of gravity gradient tensor and their application to estimate source location, Geophysics, 75(6), i59–i74.Bui C.Q. (chief author), Le T., Tran T. D., Nguyen T. H., Phi T.T., 2007. Map of deep structure of the Earth’s crust, Atlas of the characteristics of natural conditions and environment in Vietnam’s waters and adjacent region. Publisher of Science and Technology, Ha Noi. Do D.T., Nguyen T.T.H., 2011. Atempt the improvement of inversion of magnetic anomalies of two dimensional polygonal cross sections to determine the depth of magnetic basement in some data profile of middle off shelf of Vietnam. Journal of Science and Technology, Vietnam Academy of Science and Technology, 49(2), 125–132.Do D.T., 2013. Study for application of 3D magnetic and gravity method to determine density contribution of basement rock and depth of magnetic basement on Vietnam’s shelf for oil research and prospecting Vietnam National University, Hanoi, Project code QG-11-04. Keating P. and Pilkington M., 2000, Euler deconvolution of the analytic signal, 62nd Annual International Meeting, EAGE, Session P0193.Keating P., Zerbo L., 1996. An improved technique for reduction to the pole at low latitudes, Geophysics, 61, 131–137.Le H.M., Luu V.H., 2003. Preliminary interpretation of the magnetic anomalies of the Eastern Vietnam sea and adiacent regions. J.  Sci. of the Earth, 25(2), 173–181. Mai T.T., Pham V.T., Dang V.B., Le D.B., Nguyen B., Le V.D., 2011. Characteristics of Pliocene - Quaternary geology and Geoengineering in the Center and Southeast parts of Continental Shelf of Vietnam. J.  Sci.  of the Earth, 33(2), 109-118.Mushayandebvu M.F., Lesur V., Reid A.B., Fairhead J.D., 2004. Grid Euler deconvolution with constraints for 2D structures, Geophysics, 69, 489–496.Nguyen N.T., Bui V.N., Nguyen T.T.H., Than D.L., 2014a. Application of power density spectrum of magnetic anomaly to estimate the structure of magnetic layer of the earth crust in the Bac Bo gulf. Journal of Marine Science and Technology, 14(4A), 137–148.Nguyen N.T., Bui V.N., Nguyen T.T.H., 2014b. Determining the depth to the magnetic basementand fault systems in Tu Chinh - Vung May area  by magnetic data interpretation. Journal of Marine Science and Technology, 14(4A), 16–25.Nguyen T.T.H., Pham T.L., Do D.T., Le H.M., 2018. Improving algorithm of determining the coordinates of the vertices of the polygon to invert magnetic anomalies of two-dimensional basement structures in space domain, Journal of Marine Science and Technology (preparing to print).Parker R.L., 1973. The rapid calculation of potential anomalies, Geophys. J. Roy. Astron. Soc, 31, 447–455. Pilkington M., Gregotski M.E., Todoeschuck J.P., 1994. Using fractal crustal magnetization models in magnetic interpretation, Geophysical Prospecting, 42, 677–692.Pilkington M., 2006. Joint inversion of gravity and magnetic data for two-layer models, Geophysics, 71, L35–L42.Rao D.B., Babu N.R., 1993. A fortran 77 computer program for three dimensional inversion of magnetic anomalies resulting from multiple prismatic bodies, Computer & Geosciences, 19(8), 781–801.Tanaka A., Okubo Y., Matsubayashi O., 1999. Curie point depth based on spectrum analysis of the magnetic anomaly data in East and Southeast Asia, Tectonic Pphysics, 306, 461–470.Thompson D.T., 1982. EULDTH – A new technique for marking computer-assisted depth estimates from magnetic data, Geophysics, 47, 31–37.Vo T.S., Le H.M., Luu V.H., 2005. Determining the horizontal position and depth of the density discontinuties in Red River Delta by using the vertical derivative and Euler deconvolution for the gravity anomaly data, Vietnam. Journal of Geology, Series A, 287(3–4), 39–52.  Werner S., 1955. Interpretation of magnetic anomalies of sheet-like bodies, Sveriges Geologiska Undersokning, Series C, Arsbok, 43, 6.Xu S.Z., 2006. The integral-iteration method for continuation of potential fields, Chinese journal of geophysics (in Chinese), 49(4), 1176–1182.Zhang C., Huang D.N., Zhang K., Pu Y.T., Yu P., 2016. Magnetic interface forward and inversion method based on Padé approximation, Applied Geophysics, 13(4), 712–720.CCOP, 1996. Magnetic anomaly map of East Asia, scale 1:4.000.000, Geological survey of Japan and Committee for co-ordination of joint prospecting for mineral resources in asian offshore areas.


2021 ◽  
Author(s):  
Ran Issachar ◽  
Jörg Ebbing ◽  
Dilixiati Yixiati ◽  
Nils Holzrichter

<p>We explore the lithosphere structure of the Red Sea using gravity and magnetic data.</p><p>We re-processed marine data form past surveys conducted during the 70’s and the 80’s, available at the NGDC database. By correcting the magnetic measurements according to the DGRF (definitive magnetic reference field), leveling and replacing the long wavelengths with satellite data (LCS1 model) we managed to generate a consistent magnetic anomaly map for the entire length of the Red Sea that is composed of 10 different surveys and contain overs 100,000 measuring points. The magnetic anomaly map highlights structural differences between the southern, central and northern parts of the Red Sea.</p><p>Using forward gravity approach, constrains from seismic, wells and petrophysical data, and by integrating insights from magnetic analysis, we define the lithospheric model of the Red Sea to address key questions regarding rifting, sea floor spreading and transition processes.  For example, the southern parts of the Red Sea are characterized by shallow and wide asthenosphere upwelling, while in the axial trough lithosphere is thin with thicknesses of less than 15 km. The lithosphere thickness increase asymmetrically towards the rift shoulders. In general, the lithosphere is thicker on the eastern sides than on the western sides. In the central parts of the Red Sea, the lithosphere structure is not significantly different from the southern parts, however, asthenosphere upwelling is slightly narrower. In northern parts of the Red Sea asthenosphere upwelling significantly narrows and focused mainly beneath the axial trough and the lithosphere is thicker. This architecture reflects the currently transition from continental rifting (in the north) to oceanic seafloor spreading (in the south) in the Red Sea.</p>


Geophysics ◽  
1966 ◽  
Vol 31 (4) ◽  
pp. 803-811 ◽  
Author(s):  
M. H. P. Bott ◽  
R. A. Smith ◽  
R. A. Stacey

A two‐dimensional form of the pseudo‐gravity transformation, applicable to bodies magnetized in directions not parallel to the ambient field, is given. Assuming that a body of finite cross section is magnetized in the same direction and sense at every point, then an adaptation of this pseudo‐gravity transformation enables the direction of magnetization of the body to be estimated, within limits, from the magnetic anomaly it causes. The method has been programmed for a computer. A simple extension enables it to be applied to three‐dimensional bodies. The method is shown to be reliable by testing it against calculated magnetic profiles over geometrical shapes. It is applied to the Lambay magnetic anomaly in the west Irish Sea, showing this to be caused by a body magnetized approximately in the direction of the present earth’s field.


Author(s):  
O. Faroon ◽  
F. Al-Bagdadi ◽  
T. G. Snider ◽  
C. Titkemeyer

The lymphatic system is very important in the immunological activities of the body. Clinicians confirm the diagnosis of infectious diseases by palpating the involved cutaneous lymph node for changes in size, heat, and consistency. Clinical pathologists diagnose systemic diseases through biopsies of superficial lymph nodes. In many parts of the world the goat is considered as an important source of milk and meat products.The lymphatic system has been studied extensively. These studies lack precise information on the natural morphology of the lymph nodes and their vascular and cellular constituent. This is due to using improper technique for such studies. A few studies used the SEM, conducted by cutting the lymph node with a blade. The morphological data collected by this method are artificial and do not reflect the normal three dimensional surface of the examined area of the lymph node. SEM has been used to study the lymph vessels and lymph nodes of different animals. No information on the cutaneous lymph nodes of the goat has ever been collected using the scanning electron microscope.


Author(s):  
Michelle Carvalho de Sales ◽  
Rafael Maluza Flores ◽  
Julianny da Silva Guimaraes ◽  
Gustavo Vargas da Silva Salomao ◽  
Tamara Kerber Tedesco ◽  
...  

Dental surgeons need in-depth knowledge of the bone tissue status and gingival morphology of atrophic maxillae. The aim of this study is to describe preoperative virtual planning of placement of five implants and to compare the plan with the actual surgical results. Three-dimensional planning of rehabilitation using software programs enables surgical guides to be specially designed for the implant site and manufactured using 3D printing. A patient with five teeth missing was selected for this study. The patient’s maxillary region was scanned with CBCT and a cast model was produced. After virtual planning using ImplantViewer, five implants were placed using a printed surgical guide. Two weeks after the surgical procedure, the patient underwent another CBCT scan of the maxilla. Statistically significant differences were detected between the virtually planned positions and the actual positions of the implants, with a mean deviation of 0.36 mm in the cervical region and 0.7 mm in the apical region. The surgical technique used enables more accurate procedures when compared to the conventional technique. Implants can be better positioned, with a high level of predictability, reducing both operating time and patient discomfort.


2019 ◽  
Vol 20 (7) ◽  
pp. 661-665
Author(s):  
Cunxi Nie ◽  
Fei Xie ◽  
Ning Ma ◽  
Yueyu Bai ◽  
Wenju Zhang ◽  
...  

As a major component of biologically active compounds in the body, proteins contribute to the synthesis of body tissues for the renewal and growth of the body. The high level of dietary protein and the imbalance of amino acid (AA) composition in mammals result in metabolic disorders, inefficient utilization of protein resources and increased nitrogen excretion. Fortunately, nutritional interventions can be an effective way of attenuating the nitrogen excretion and increasing protein utilization, which include, but are not limited to, formulating the AA balance and protein-restricted diet supplementing with essential AAs, and adding probiotics in the diet. This review highlights recent advances in the turnover of dietary proteins and mammal’s metabolism for health, in order to improve protein bioavailability through nutritional approach.


2021 ◽  
pp. 0308518X2199781
Author(s):  
Xinyue Luo ◽  
Mingxing Chen

The nodes and links in urban networks are usually presented in a two-dimensional(2D) view. The co-occurrence of nodes and links can also be realized from a three-dimensional(3D) perspective to make the characteristics of urban network more intuitively revealed. Our result shows that the external connections of high-level cities are mainly affected by the level of cities(nodes) and less affected by geographical distance, while medium-level cities are affected by the interaction of the level of cities(nodes) and geographical distance. The external connections of low-level cities are greatly restricted by geographical distance.


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