scholarly journals Shatter cones: (Mis)understood?

2016 ◽  
Vol 2 (8) ◽  
pp. e1600616 ◽  
Author(s):  
Gordon R. Osinski ◽  
Ludovic Ferrière
Keyword(s):  
Accurate Method ◽  
Small Region ◽  
Impact Craters ◽  
Meteorite Impact ◽  
Geological Features ◽  
Cone Formation ◽  
Apparent Diameter ◽  
Shatter Cones ◽  
Evidence Of Impact

Meteorite impact craters are one of the most common geological features in the solar system. An impact event is a near-instantaneous process that releases a huge amount of energy over a very small region on a planetary surface. This results in characteristic changes in the target rocks, from vaporization and melting to solid-state effects, such as fracturing and shock metamorphism. Shatter cones are distinctive striated conical fractures that are considered unequivocal evidence of impact events. They are one of the most used and trusted shock-metamorphic effects for the recognition of meteorite impact structures. Despite this, there is still considerable debate regarding their formation. We show that shatter cones are present in several stratigraphic settings within and around impact structures. Together with the occurrence of complete and “double” cones, our observations are most consistent with shatter cone formation due to tensional stresses generated by scattering of the shock wave due to heterogeneities in the rock. On the basis of field mapping, we derive the relationshipDsc= 0.4Da, whereDscis the maximum spatial extent of in situ shatter cones, andDais the apparent crater diameter. This provides an important, new, more accurate method to estimate the apparent diameter of eroded complex craters on Earth. We have reestimated the diameter of eight well-known impact craters as part of this study. Finally, we suggest that shatter cones may reduce the strength of the target, thus aiding crater collapse, and that their distribution in central uplifts also records the obliquity of impact.

Low diffusion level within a fibroadenoma as the sole sign of ductal carcinoma in situ: A case report

2021 ◽  
pp. 1-4
Author(s):  
Corrado Tagliati ◽  
Giuseppe Lanni ◽  
Federico Cerimele ◽  
Antonietta Di Martino ◽  
Valentina Calamita ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Ductal Carcinoma In Situ ◽  
Carcinoma In Situ ◽  
Ductal Carcinoma ◽  
Surgical Excision ◽  
Small Region ◽  
Apparent Diffusion Coefficient Value ◽  
Apparent Diffusion

We present a case of ductal carcinoma in situ within a fibroadenoma. Breast cancer arising within fibroadenoma incidence ranges from 0.125% to 0.02%, and ductal carcinoma in situ is not the most frequent malignancy that can be found within a fibroadenoma. Dynamic contrast-enhanced magnetic resonance imaging showed an oval mass with circumscribed margins and dark internal septations, suspicious for fibroadenoma. According to European Society of Breast Radiology diffusion-weighted imaging consensus, mean apparent diffusion coefficient value obtained by drawing a small region of interest on the lesion apparent diffusion coefficient map showed a low diffusion level. Therefore, ductal carcinoma in situ within a fibroadenoma was diagnosed at final pathology after surgical excision.

scholarly journals Meteorite impact craters as hotspots for mineral resources and energy fuels: A global review

2021 ◽  
Author(s):  
S. James ◽  
Saranya R. Chandran ◽  
M. Santosh ◽  
A.P. Pradeepkumar ◽  
M.N. Praveen ◽  
...  
Keyword(s):  
Mineral Resources ◽  
Impact Craters ◽  
Meteorite Impact

scholarly journals A new method based on diffusive gradients in thin films for in situ monitoring microcystin-LR in waters

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lei Yao ◽  
Alan D. Steinman ◽  
Xiang Wan ◽  
Xiubo Shu ◽  
Liqiang Xie
Keyword(s):  
Thin Films ◽  
Passive Sampling ◽  
Sampling Method ◽  
Binding Capacity ◽  
Accurate Method ◽  
In Situ Monitoring ◽  
Active Sampling ◽  
Binding Agent ◽  
Diffusive Gradients

AbstractThe passive sampling method of diffusive gradients in thin-films (DGT) was developed to provide a quantitative and time-integrated measurement of microcystin-LR (MC-LR) in waters. The DGT method in this study used HLB (hydrophilic-lipophilic-balanced) material as a binding agent, and methanol as an eluent. The diffusion coefficient of MC-LR was 5.01 × 10−6 cm2 s−1 at 25 °C in 0.45 mm thick diffusion layer. This DGT method had a binding capacity of 4.24 μg per binding gel disk (3.14 cm2), ensuring sufficient capacity to measure MC-LR in most water matrices. The detection limit of HLB DGT was 0.48 ng L−1. DGT coupled to analysis by HPLC appears to be an accurate method for MC-LR monitoring. Comparison of DGT measurements for MC-LR in water and a conventional active sampling method showed little difference. This study demonstrates that HLB-based DGT is a useful tool for in situ monitoring of MC-LR in fresh waters.

The exploration potential of Australia’s meteorite impact craters

2006 ◽  
Vol 2006 (1) ◽  
pp. 1-6 ◽  
Author(s):  
P. J. Hawke ◽  
M. C. Dentith
Keyword(s):  
Impact Craters ◽  
Meteorite Impact

Orientation of planar element systems in quartz from rocks of meteorite impact craters

1981 ◽  
Vol 23 (1) ◽  
pp. 11-16
Author(s):  
Ye. P. Gurov ◽  
Ye. P. Gurova ◽  
R. B. Rakitskaya
Keyword(s):  
Impact Craters ◽  
Meteorite Impact

scholarly journals The accuracy of Intramedullary Femoral alignment in Total Knee Replacement in the prescence of ipsilateral Hip Replacement

2017 ◽  
Vol 5 (5_suppl5) ◽  
pp. 2325967117S0016
Author(s):  
A/Prof Michael Reid ◽  
Dr Benjamin Parkinson ◽  
Dr Adam Parr ◽  
Dr Christopher Conyard ◽  
Dr Drew Armit ◽  
...  
Keyword(s):  
Total Knee Replacement ◽  
Knee Replacement ◽  
Hip Replacement ◽  
Mechanical Axis ◽  
Computer Navigation ◽  
Accurate Method ◽  
Revision Stem ◽  
Number Of Patients ◽  
Total Knee

Objectives: During total knee replacement (TKR) surgery, the most commonly used method for aligning the distal femur appropriately is via an intramedullary (IM) distal femoral alignment rod. The alignment of the rod itself is reliant on the isthmus which is used to most accurately place the rod in the correct anatomical axis. In the instance of something preventing the rod from entering the isthmus correctly, such as a hip replacement, then the degree of accuracy could be assumed to be even less. Mechanical-anatomical malalignment has been shown to decrease the implant (TKR) survival and so methods of increasing accuracy of alignment relative to the mechanical axis have been developed. At present the most accurate method intraoperatively is computer navigation and several studies have demonstrated improved alignment. An increasing number of patients year on year are having both knee and hip replacements and as the population ages the likelihood of having both a knee and hip replacement will also increase. We propose that the presence of a hip replacement within the isthmus of the femur may further decrease the accuracy of the IM alignment of the femur leading to incorrect implant positioning. Methods: The study was conducted on 10 cadaveric specimens (20 femurs). Computational navigation instrumentation was attached in turn to each femur and the ideal alignment data recorded in a standard fashion by a single operator (principal investigator). A standard entry port was then be made in the femur for the introduction of the IM rod. An IM rod was then inserted with the distal femoral cutting block in the accepted position recorded blindly on the computer navigation (both in terms of varus/valgus alignment to the mechanical axis and the degree of flexion). The process was then repeated at 3 levels to represent primary and revision hip lengths from the greater trochanter (replicating the changes that would occur in the presence of a hip replacement) The process was recorded three times at each level. Results: The resection angles between the cutting surface and the mechanical axis were measured and collected by means of computer navigation system. The results show that the IM alignment had mean Valgus of 0 degrees +/- 0.8 but with a hip replacement in situ this increased to 0.46 degrees +/- 1.49 (range 2.5 varus to 4.5 valgus), with a revision stem 0.825 +/- 1.68 (range 2.5 varus to 4.5 valgus) and long stemmed revision 1.325 +/- 2.09 (range 5 varus to 6.5 valgus). In terms of Flexion IM alignment had a mean flexion of 0.92 +/- 1.7 (range 3 extension to 4 flexion) but with a hip replacement in situ this increased to 1.88 degrees +/- 2.03 (range 2.5 extension to 8.5 flexion), with a revision stem 2.35 +/- 2.2 (range 2.5 extension to 8 flexion) and long stemmed revision 2.75 +/- 2.16 (range 3.5 extension to 7 flexion). Conclusion: This Study concludes that the prescence of a hip replacement, in particular long stemmed prosthesis, further reduces the accuracy of IM alignment in the Femur for Total Knee Replacement. Consideration of an alternative method, such as navigation, should be considered in such situations.

Geology and geochemistry of the molybdenite showings of the Ackley City batholith, southeast Newfoundland

1980 ◽  
Vol 17 (9) ◽  
pp. 1246-1258 ◽  
Author(s):  
J. B. Whalen
Keyword(s):  
Trace Elements ◽  
Vapour Phase ◽  
Major And Trace Elements ◽  
Composite Body ◽  
Precambrian Rocks ◽  
Geological Features ◽  
Tectonic Zones ◽  
Host Rocks ◽  
Residual Melt

The Ackley City batholith of southeast Newfoundland is an oval-shaped granitoid of approximately 5400 km2 which intruded Ordovician and Precambrian rocks of the Gander and Avalon tectonic zones, respectively, about 345 Ma ago. It is a composite body, consisting mainly of K-feldspar megacrystic granite and alaskite. Spatially related to the southeast contact of the alaskite are younger aplites and pegmatites within which are six separate molybdenite showings. The showings vary in their type of host rocks and in features of mineralization and alteration, but can all be classed as being of aplite–pegmatite type.This notably felsic (SiO2 > 71.8%) pluton has alkaline affinities and features indicative of derivation from an igneous source (I-type). Some major and trace elements exhibit considerable variations. These variations and other geological features indicate that aplites and pegmatites formed by in situ fractional crystallization of the alaskite at shallow depths (1.8 to 3.7 km) to produce a roof-zone complex. Mo is localized in these rocks, which formed from the final residual melt and coexisting vapour phase, and is considered to be closely genetically related to them.

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