Paleomagnetism of Archean rocks from northwestern Ontario: IV. Burchell Lake granite, Wawa–Shebandowan Subprovince

1984 ◽  
Vol 21 (10) ◽  
pp. 1098-1104 ◽  
Author(s):  
David J. Dunlop
Keyword(s):  
Natural Remanent Magnetization ◽  
Reverse Polarity ◽  
Polar Wander ◽  
Apparent Polar Wander Path ◽  
Northwestern Ontario ◽  
Normal Polarity ◽  
The Mean ◽  
Low K

The late Archean Burchell Lake granite of the Shebandowan greenstone belt in northwestern Ontario has a characteristic natural remanent magnetization (NRM) resembling the type 1 NRM of the nearby Shelley Lake granite of the Quetico gneiss belt. Of 36 stably magnetized samples, 21 had predominantly normal polarity (1N) NRM and 15 had reverse polarity (1R). The mean direction based on stable end-point and vector subtracted directions is D = 2.3 °I = 48.9 °(k = 23.9, α95 = 10.0°, N = 10 sites). Intersecting remagnetization circles gave a similar direction. The corresponding paleopole BL1 lies at 83.2°E, 71.1°N, near track 6 of the Laurentian apparent polar wander path around 2600 Ma. Although the Burchell Lake pluton is not dated radiometrically, neighbouring granites give K/Ar biotite ages of 2550–2600 Ma, and it is reasonable to suppose that the NRM dates from the time of intrusion or shortly thereafter. A type 2 NRM like that of the Shelley Lake granite was isolated in 12 samples. Its mean direction is D = 80.9 °I = −11.1°, but the precision is unacceptably low (k = 7.7).

Paleomagntism of Archean rocks from northwestern Ontario: II. Shelley Lake granite, Quetico Subprovince

1984 ◽  
Vol 21 (8) ◽  
pp. 869-878 ◽  
Author(s):  
David J. Dunlop
Keyword(s):  
Dipole Field ◽  
Polar Wander ◽  
Orthogonal Vector ◽  
Site Type ◽  
Apparent Polar Wander Path ◽  
Northwestern Ontario ◽  
Heating Event ◽  
The Mean

The 2580 ± 20 Ma Shelley Lake granite of the Quetico gneiss belt in northwestern Ontario preserves two distinct natural remanent magnetizations (NRM's) of different ages. Type 1 NRM of either normal (1N) or reverse (1R) polarity was isolated in 43 samples, using three methods: stable end-point directions, orthogonal vector plots, and converging remagnetization circles. The mean direction based on both 1N and 1R results is D = 5.9 °I = +56.4 °(k = 95.4, α95 = 4.4°, N = 12 sites), which is significantly different from both the present Earth's field (PEF) and axial dipole field directions at the site. Type 2 NRM, either normal (2N) or reverse (2R), was successfully separated from 1N/1R in 13 samples. Its mean direction, combining both polarities, is D = 70.3 °I = −27.8 °(k = 20.1, α95 = 9.4°, N = 13 samples).The paleopole SL1 corresponding to 1N/1R falls at 65.8°E, 77.6°N, near track 6 of the Laurentian apparent polar wander path (APWP) around 2600 Ma. This remanence is carried principally by primary multidomain magnetite with blocking temperatures up to 580 °C. If it is a primary thermoremanence, as is argued here, SL1 provides a well dated tie point for the APWP at 2580 ± 20 Ma.Paleopole SL2 corresponding to 2N/2R falls at 157.1°W, 1.3°S, around 1250 Ma on the APWP. The remanence is probably a chemical or thermochemical overprint acquired during a mild heating event (T < 300 °C, t > 1100 Ma) that reset 40Ar/39Ar feldspar ages. An earlier tentative assignment of SL2 to track 6 around 2800 Ma is incorrect.

Paleomagnetism of Archean rocks from northwestern Ontario: V. Poohbah Lake alkaline complex, Quetico Subprovince

1985 ◽  
Vol 22 (1) ◽  
pp. 27-38 ◽  
Author(s):  
David J. Dunlop
Keyword(s):  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Reverse Polarity ◽  
Alkaline Complex ◽  
Field Reversal ◽  
Polar Wander ◽  
Fine Grained ◽  
Rock Types ◽  
Northwestern Ontario ◽  
Normal Polarity

The Poohbah Lake alkaline complex is a late synkinematic Kenoran pluton in the Quetico gneiss belt of the western Superior Province. Three units of the complex, porphyritic syenite (PS), malignite (M: a nepheline–clinopyroxene–K-feldspar rock), and hornblende syenite (HS), as well as baked Archean schists near the intrusive contact, have a predominantly reverse-polarity R magnetization with mean direction D = 198° I = −22.5° (k = 62, α95 = 5°, N = 13 sites) and a paleopole at 60°E, 50.5°N. Pyrrhotite and coarse primary magnetite are carriers of the R remanence. PS, M, and biotite pyroxenite (BP) exhibit also a predominantly normal N magnetization carried by fine-grained, probably secondary magnetite. N is systematically steeper than R: its mean direction is D = 359.5° I = +55.5° (k = 28, α95 = 8°, N = 13 sites) with a paleopole at 90°E, 77.5°N. R and N do not record an asymmetric field reversal, since reverse-polarity N vectors and normal-polarity R vectors are occasionally found. R resembles in polarity and direction the natural remanent magnetization (NRM) of the 2630 Ma Matachewan diabase. It is probably the primary NRM of the Poohbah Lake pluton, with an age of about 2650 Ma in approximate agreement with the K/Ar isochron age of 2700 ± 25 Ma. N resembles in polarity and direction NRM's from the 2580 Ma Shelley Lake granite and the late Archean Burchell Lake granite. It is probably a secondary NRM about 2550 Ma in age, as suggested by updated K/Ar mica ages. The characteristic NRM of HS samples and secondary magnetizations in other rock types have poles on the Grenville Track of the polar wander path but there is no evidence for Grenvillian-age events in the area.

Paleomagnetism of Archean rocks from northwestern Ontario: III. Rock magnetism of the Shelley Lake granite, Quetico Subprovince

1984 ◽  
Vol 21 (8) ◽  
pp. 879-886 ◽  
Author(s):  
David J. Dunlop ◽  
Larry D. Schutts ◽  
Christopher J. Hale
Keyword(s):  
Remanent Magnetization ◽  
Rock Magnetism ◽  
Natural Remanent Magnetization ◽  
Thermal Decay ◽  
Magnetic Phases ◽  
Northwestern Ontario ◽  
Component Type ◽  
Thermal Overprint

The Shelley Lake granite of northwestern Ontario contains five magnetic phases: deuteric and post-crystallization hematites, which are relatively abundant but carry only 1–4% of the natural remanent magnetization (NRM); primary magnetite in coarse (50–500 μm) grains, both optically homogeneous and subdivided by hematite lamellae; micrometre-size secondary magnetite in chloritized biotites; and submicrometre-size magnetite, whose presence is inferred from low blocking temperatures in thermal decay curves of the NRM. The NRM is a composite of type 1 and type 2 remanences, which differ in direction by about 90° (see companion paleomagnetic paper). Both NRM components occur in normal (N) and reverse (R) polarities. Type 1 remanences (1N/1R) have the hallmarks of multidomain (MD) behaviour: high blocking temperatures but low coercivities, exponential alternating field (AF) decay curves, generally MD results of the Lowrie–Fuller test, and MD to transitional values (0.3–10) of the Koenigsberger Qn ratio. Furthermore, intensities of 0.6 Oe (0.06 mT) laboratory thermoremanent magnetizations (TRM's) match those of 1R and some 1N NRM's. We argue on this evidence that 1R and at least part of 1N NRM's are TRM's residing in coarse MD-size primary magnetite. This primary TRM dates from initial cooling of the Shelley Lake pluton around 2580 Ma. Thermal decay spectra of single-component type 2 NRM's (2N/2R) resemble those of 1R. However, the considerable overlap of 2N/2R and 1R blocking temperatures in multivectorial NRM's demonstrates that type 2 remanence must be a chemical or thermochemical rather than a thermal overprint.

Paleomagnetism of Archean rocks from northwestern Ontario: Wabigoon gabbro, Wabigoon Subprovince

1983 ◽  
Vol 20 (12) ◽  
pp. 1805-1817 ◽  
Author(s):  
David J. Dunlop
Keyword(s):  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Blocking Temperature ◽  
Virtual Geomagnetic Pole ◽  
Polar Wander ◽  
Apparent Polar Wander Path ◽  
Northwestern Ontario ◽  
Paleomagnetic Pole ◽  
Geomagnetic Pole ◽  
Chemical Remanent Magnetization

The Wabigoon gabbro of the Archean Wabigoon greenstone belt in northwestern Ontario preserves a univectorial natural remanent magnetization (NRM) with D = 246°, I = 12° (k = 19.5, α95 = 10.5°, N = 11 sites). The precision is reduced if sample means are averaged, however (k = 9.3, α95 = 9.2°, N = 29 samples). The paleomagnetic pole falls either at 160°W, 11°S (δp = 5.3°, δm = 10.6°), corresponding to an age of ~1300 Ma on the Laurentian apparent polar wander path, or the reverse of this, 20°E, 11° N, corresponding to a late Archean age (~2800 Ma). No ~1300 Ma igneous or metamorphic event is known in the area; a major west-northwest-trending dike about 9 km south of the gabbro yields a virtual geomagnetic pole at 122°W, 45°N and seems to be of Abitibi age (~2150 Ma) rather than Mackenzie age (~1250 Ma). A few gabbro samples and some greenstones from the intrusive baked zone have hybrid remanences in which a higher blocking temperature Kenoran-age (~2600 Ma) NRM is superimposed on the gabbro characteristic NRM. However, the Kenoran component may be a younger chemical remanent magnetization (CRM) residing in hematite. The hypothesis that the gabbro characteristic remanence is itself a hybrid of Kenoran and Keweenawan (~1100 Ma) NRM's, which would explain both the high between-sample scatter and the lack of a ~1300 Ma remagnetizing event, is considered but rejected because fewer than 10% of the gabbro samples exhibit multivectorial swings during alternating field or thermal cleaning. Two geomagnetic field reversals are recorded at interior sites, but only one or none is recorded near the margin of the intrusion. The different cooling histories of margin and interior, as well as the bulk of the other evidence, favour magnetization during initial cooling in late Archean time.

scholarly journals Modified approach to the characterization of adrenal nodules using a standard abdominal magnetic resonance imaging protocol

2017 ◽  
Vol 50 (1) ◽  
pp. 19-25 ◽  
Author(s):  
António P. Matos ◽  
Richard C. Semelka ◽  
Vasco Herédia ◽  
Mamdoh AlObaidiy ◽  
Filipe Veloso Gomes ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Imaging Protocol ◽  
Intensity Index ◽  
Abdominal Magnetic Resonance Imaging ◽  
Phase Type ◽  
The Mean ◽  
Magnetic Resonance Imaging Protocol ◽  
Type 3

Abstract Objective: To describe a modified approach to the evaluation of adrenal nodules using a standard abdominal magnetic resonance imaging protocol. Materials and Methods: Our sample comprised 149 subjects (collectively presenting with 132 adenomas and 40 nonadenomas). The adrenal signal intensity index was calculated. Lesions were grouped by pattern of enhancement (PE), according to the phase during which the wash-in peaked: arterial phase (type 1 PE); portal venous phase (type 2 PE); and interstitial phase (type 3 PE). The relative and absolute wash-out values were calculated. To test for mean differences between adenomas and nonadenomas, Student's t-tests were used. Receiver operating characteristic curve analysis was also performed. Results: The mean adrenal signal intensity index was significantly higher for the adenomas than for the nonadenomas (p < 0.0001). Chemical shift imaging showed a sensitivity and specificity of 94.4% and 100%, respectively, for differentiating adenomas from nonadenomas. Of the adenomas, 47.6%, 48.5%, and 3.9%, respectively, exhibited type 1, 2, and 3 PEs. For the mean wash-in proportions, significant differences were found among the enhancement patterns. The wash-out calculations revealed a trend toward better lesion differentiation for lesions exhibiting a type 1 PE, showing a sensitivity and specificity of 71.4% and 80.0%, respectively, when the absolute values were referenced, as well as for lesions exhibiting a type 2 PE, showing a sensitivity and specificity of 68.0% and 100%, respectively, when the relative values were referenced. The calculated probability of a lipid-poor lesion that exhibited a type 3 PE being a nonadenoma was > 99%. Conclusion: Subgrouping dynamic enhancement patterns yields high diagnostic accuracy in differentiating adenomas from nonadenomas.

scholarly journals There is a Correlation between Fragility Fractures of the Pelvis and a Circle-Type Morphology of the True Pelvis, but Not with Pelvic Incidence

2021 ◽  
pp. 1-6
Author(s):  
Matthias Spalteholz ◽  
Matthias Spalteholz ◽  
Gulow Jens ◽  
Pap Geza
Keyword(s):  
Pelvic Incidence ◽  
Fragility Fractures ◽  
Statistical Correlation ◽  
X Ray ◽  
Lack Of Information ◽  
The Mean ◽  
Fracture Types ◽  
Type 3

Purpose: Osteoporosis is a major risk factor for the development of fragility fractures of the pelvis (FFP). There is a lack of information about the influence of anatomical conditions such as Pelvic Incidence and Pelvic Ratio (DT/DS ratio) on this kind of fractures. Methods: This is a monocentric retrospective analysis. X-ray images of the lumbar spine and pelvis and 3D-MPR CT reconstructions of the pelvis were analysed to determine Pelvic Incidence (PI) and Pelvic Ratio (PR) in 141 fragility fractures of the pelvis. Statistical analyses were performed to examine the correlation between these spinopelvic parameters and fragility fractures of the pelvis. Results: A total of 141 fragility fractures of the pelvis (14 men = 9.93%, 127 women = 90.07%) were analysed. According to the FFP-classification we recognized FFP type 1 fractures in 19.15%, FFP type 2 in 41.13%, FFP type 3 in 8.51% and FFP type 4 fractures in 32.21%. The mean PI was 58.83º. There was no statistical correlation between PI and fracture types (p=0.81). The mean PR was 1.099. 57 patients (40.43%) demonstrated a DT/DS ratio ≤ 1.06, corresponding to a circle-type morphology. 24 patients (17.02%) demonstrated a DT/DS ratio ≥ 1.18, corresponding to an ellipse-type pelvis. A circle-type pelvis is significantly more often associated with fragility fractures of the pelvis than an ellipse-type morphology (p<0.001). Conclusion: The results of our work demonstrate a strong statistical correlation between the circle-type morphology of the pelvis (PR ≤ 1.06) and fragility fractures of the pelvis. There is no statistical correlation between fragility fractures of the pelvis and Pelvic Incidence.

scholarly journals Expression of cyclooxygenase-2 in orbital fibroadipose connective tissues of Graves’ ophthalmopathy patients

2006 ◽  
Vol 155 (5) ◽  
pp. 681-685 ◽  
Author(s):  
E Berrin Yuksel Konuk ◽  
Onur Konuk ◽  
Muge Misirlioglu ◽  
Adnan Menevse ◽  
Mehmet Unal
Keyword(s):  
Disease Duration ◽  
Clinical Activity ◽  
Connective Tissues ◽  
Positive Correlation ◽  
Graves Ophthalmopathy ◽  
Compressive Neuropathy ◽  
The Mean ◽  
Cox 2

Objective: The aim of this study is to evaluate the expression of cycloocygenase-2 (COX-2) in orbital fibroadipose connective tissue in Graves’ ophthalmopathy (GO) patients, and investigate the associations between COX-2 expression and GO characteristics. Methods: The orbital fibroadipose connective tissues of 23 cases demonstrating moderate or severe GO, and eight control subjects without any history of thyroid or autoimmune disease were analyzed for COX-2 mRNA expression. Real-time relative quantitative PCR was performed to assess transcripts of COX-2 using the LightCycler. The disease activity was evaluated by the clinical activity score (CAS). The clinical features of GO were evaluated by total eye score (TES) and the cases were divided into two groups; type 1 cases included higher degrees of proptosis with orbital fat volume increase, and type 2 cases included cases with compressive neuropathy and limited extraocular muscle functions. Results: The mean ± s.d. disease duration was 5.7 ± 7.1 years. The mean ± s.d. CAS and TES of cases were 1.60 ± 1.04 and 7.5 ± 1.8 respectively. The mean ± s.d. expression of COX-2 was 0.023 ± 0.013 and 0.010 ± 0.002 in GO cases and controls (P = 0.008), and 0.015 ± 0.073 and 0.029 ± 0.135 in type 1 and type 2 cases respectively (P = 0.007). COX-2 expression showed a statistically significant positive correlation with TES (r = 0.634, P = 0.001), and a negative correlation with the disease duration (r = −0.621, P = 0.002). Conclusions: COX-2 is expressed at higher levels in orbital fibroadipose tissues of GO cases. This showed a positive correlation with increasing severity of orbital disease suggesting possible relation with COX-2 expression and orbital inflammation in GO.

Mooring System Design and Optimization for Floating Bridge of Urmia Lake

2002 ◽  
Author(s):  
M. Daghigh ◽  
R. T. Paein Koulaei ◽  
M. S. Seif
Keyword(s):  
Burial Depth ◽  
Floating Bodies ◽  
Mooring Lines ◽  
Sea Floor ◽  
Design And Optimization ◽  
Sea Bed ◽  
Floating Bridge ◽  
The Mean

In order to get better understanding on the response of floating bodies, different design aspects of mooring lines has been investigated in this paper. Mooring lines are categerized into two types; the catenary settling on the sea floor (type 1) and the limited one which has no dead-length on sea floor (type 2). It has been observed that the stiffness of both types may be well predicted by Jain’s formulation and in the design process of floating bodies the mooring lines may be replaced by uncoupled horizontal and vertical springs. On the other hand, the anchor capacity against sliding and release from the mean still water has been studied in this paper. From the results of a parametric study, using the discrete element method, the block anchor the dimensions for the Urmia floating bridge has been optimized and the behavior of anchor and seabed deposits for release of block anchor indicates that the burial depth and the stress level on the block anchor itself and the sea bed are in the allowable and elastic region, respectively.

scholarly journals Estimating Utility value for Female Genital Mutilation

2020 ◽  
Author(s):  
Cyrus Alinia ◽  
Bakhtiar Piroozi ◽  
Fariba Jahanbin ◽  
Hossein Safari ◽  
Amjad Mohamadi-Bolbanabad ◽  
...  
Keyword(s):  
Female Genital Mutilation ◽  
Health Utility ◽  
Utility Value ◽  
Genital Mutilation ◽  
Lower Health ◽  
The Mean ◽  
Socio Demographic Factors ◽  
Female Genital

Abstract Background: Female genital mutilation/cutting (FGM/C) is a clear violation of women's rights and can have adverse and irreversible health effects as well. Worldwide, more than 200 million women and girls have undergone FGM/C. Utility value of FGM/C has not been estimated yet, so we designed this study to extract the health utility value of FGM/C for the first time in the world.Methods: In a cross-sectional study in Iran, 125 girls and women who underwent FGM/C procedure were examined by the trained midwives in order to determine its type. In addition, a questionnaire was completed for identifying the socio-demographic factors and extracting the health utility of these individuals. Health utility was measured using Time Trade-off method and also to determine the effects of the socio-demographic factors on the health utility a two-limit censored regression model was applied.Results: The mean and median of the health utility of women with FGM/C were 0.971 (SE: 0.003) and 0.968 (IQR: 1-0.95), respectively. Number of non-traders was 58 (46.4%) who reported perfect health utility. However, the mean of health utility among traders was 0.946 (SE: 0.002). Only type 1 (Clitoridectomy) and type 2 (Excision) FGM/C were seen in this study. Women with Type 1 FGM/C had significantly lower health utility value (Mean: 0.968, Median: 0.957) than their type 2 counterparts (Mean: 0.987, Median: 1.00). Moreover, women in the age group of 31-45 years (Mean: 0.962, Median: 0.956), single (Mean: 0.950, Median: 0.954), divorced (Mean: 0.951, Median: 0.950), employed (Mean: 0.959, Median: 0.956), and with supplementary insurance (Mean: 0.962, Median: 0.950) had significantly lower health utility than their counterparts.Conclusion: FGM/C affects physical and psychological well-being of these individuals, resulting in a lack of personal and marital satisfaction, which ultimately leads to a 3% reduction in their health related quality of life. Therefore, preventing from this practice is very important and should be considered by health system policy makers more than before.

scholarly journals Clinical and morphological characteristics of type 1 and 2 autoimmune pancreatitis

2018 ◽  
Vol 46 (4) ◽  
pp. 330-337
Author(s):  
S. V. Lishchuk ◽  
Е. A. Dubova ◽  
K. А. Pavlov ◽  
Yu. D. Udalov
Keyword(s):  
Differential Diagnosis ◽  
Autoimmune Pancreatitis ◽  
Morphological Characteristics ◽  
High Power Field ◽  
Obliterative Phlebitis ◽  
Inflammatory Infiltration ◽  
Diagnostic Potential ◽  
The Mean

Rationale: In the recent years, an increased interest to autoimmune pancreatitis (AIP) has been seen, related to growing diagnostic potential. In its turn, this leads to an increase in numbers of diagnosed AIP cases. At present, two types of AIP have been described with diverse clinical manifestation and morphology of the pancreas. However, the reproducibility of the differential diagnosis between AIP type 1 and 2 is low even among pancreatic pathologists.Aim: To identify criteria for the morphologic diagnosis of AIP type 1 and 2.Materials and methods: A morphological study of biopsy and surgical specimens from 26 patients with AIP was performed. There were 22 cases of AIP type 1 and 4 cases of AIP type 2. In addition to hematoxylin eosin staining of the specimens, immunohistochemistry was used with counting of CD138+ absolute numbers, determination of IgG+ and IgG4+ cells in the inflammatory infiltrates, as well as the ratios of IgG4+/IgG+ and IgG4+/CD138+ cells.Results: AIP type 1 was characterized by storiform fibrosis of the pancreatic tissue (81.8% cases), involving the parapancreatic fat tissue, by moderateto-severe lymphoplasmocytic infiltration and signs of obliterative/non-obliterative phlebitis. Type 2 AIP was characterized by severe fibrosis with predominantly periductal (centrilobular) fibrosis and mild chronic inflammatory infiltration of the pancreas, while there was no extension of fibrosis and inflammatory infiltration to the parapancreatic tissues in any case. The mean number of CD138+ cell in AIP type 1 was 101.2 ± 27.9 per 1 high-power field (HPF), and in AIP type 2, it was 42.8 ± 20.9 per 1 HPF. The mean absolute number of IgG+ cells in AIP type 1 was 99.6 ± 25.7 per 1 HPF, whereas in AIP type 2, 42.1 ± 20.8 per 1 HPF. In AIP type 1, the mean number of IgG4+ plasmatic cells in the infiltrates was 74.5 ± 27.2 per 1 HPF, whereas in AIP type 2, it was 3.4 ± 2.7 per 1 HPF. The IgG4+/IgG+ ratio was 75 ± 12.6% vs. 8.4 ± 6.2%, and the IgG4+/CD138+ ratio was 72.4 ± 12.3% vs. 8.3 ± 5.9% in AIP type 1 and type 2, respectively.Conclusion: For the differential diagnosis of type 1 and 2 AIP, it is necessary to take into consideration not only typical histological abnormalities, but also the numbers of CD138+, IgG+ and IgG4+ cells within the inflammatory infiltrate, as well as the IgG4+/IgG+ and IgG4+/CD138+ ratios.

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