TRIAXIAL AND INJECTION EXPERIMENTS ON ROCKS AND THEIR IMPACT ON PERMEABILITY AND ACOUSTIC EMISSIONS

Understanding the various micromechanical processes that occur in a rock under in-situ stress conditions has been a major imperative of rock mechanics. Some of the applications of rock mechanics include the science of earthquakes, improved recovery of energy from hydrocarbon and enhanced geothermal systems (EGS), civil and mining engineering to name a few. To obtain a comprehensive understanding of these micromechanical processes, triaxial experiments (heated and non –heated) have been performed while monitoring stress, strain, permeability alteration, wave velocity, and acoustic emissions. A variation of triaxial testing in which failure is caused by increasing the pore pressure of the sample during triaxial loading has also been carried out and studied. A range of rocks with a wide distribution of properties has been tested for this purpose – this includes sandstone, shale, rhyolite, rhyolitic tuff, basalt, limestones and granite. The reservoir rocks were also characterized using mineralogical and pore structure (SEM and thin sections) analysis. Permeability of is an important rock property, and in this work, rock permeability variation has been studied during triaxial compression tests for a number of tuffs and basalts from potential EGS sites. Correlations have been found which link the change in permeability after failure to the rock’s initial porosity. It has been shown that axial permeability reduces for high porosity samples while it increases for low porosity samples after triaxial loading. Using the data for a range of rocks a porosity cut-off value for transition from decrease to increase of permeability has been proposed. Porosity of all samples was also measured and has been provided – in most cases the influence of confining pressure has also been provided. In addition, Acoustic emission (AE) generation has monitored during the failure process and at various stages of triaxial deformation. Depending upon rock type, high or low AE activity has been observed. It has been observed that sandstones, granites and basalts generate high AE while limestone while certain types of tuffs rich in clay minerals do not generate much AE activity. Rocks that display ductile failure do not generate high acoustic emissions while brittle failure almost always does. In this study, ductile tuff samples generated less than 10 events up to failure whereas brittle samples from the same well generated greater than 1000 events. The AE events were located to better depict areas of high AE activity within the samples. Higher AE activity was always observed in the fractured area and zones closer to the fracture. In addition to the above temporal and spatial analysis, Moment tensor analysis has also been performed using two techniques –one simplistic based on first wave arrival and the second with full tensor inversion with the primary aim of understanding emission source type – shear, tensile or mixed. Results show that both techniques only slightly differ from each other. Energy released during fracturing, amplitude of events and their frequency has also been studied for the rocks tested. The results show that maximum energy release happens during fracturing and a range of frequencies are generated during fracturing with no specific frequency tied to fracturing process. Using the strain, stress, permeability, wave velocity and AE data sets, the micromechanical processes which usually culminate into the shear fracture has been illustrated for the rocks tested. In relation to permeability change, pore collapse and micro-cracking compete with each other during loading and depending upon the rock porosity, the final permeability may be higher or lower. It has been argued in this thesis that the above kind of analysis – combining several methods of data monitoring including stress, strain, wave velocities, permeability, mineralogical, pore structure and acoustic emission analysis with moment tensor inversion is a powerful tool for elucidating the micromechanical or macromechanical evolution of damage, during the deformation of rock. Overall it has been shown here that in a triaxial test, permeability alteration within a rock is strongly linked to rock porosity and the event of largest change in permeability always coincides with a major release of AE. It has also been shown that volumetric strain determines the changes in permeability more strongly than any other parameter. The triaxial-injection tests were completed successfully for a range of rocks. The results show that there are differences in results obtained while using this test instead of the standard triaxial test. Several high temperature tests were also performed and associated parameters calculated -it has been concluded that temperatures higher than 100 OC are needed for observing changes in elastic properties as compared to room temperature testing

Opening closets and dividing audiences: Rituparno Ghosh, the queer star of Bengali cinema

Opening closets and dividing audiences: Rituparno Ghosh, the queer star of Bengali cinem

From Teen Kanya to Arshinagar: feminist politics, Bengali high culture and the stardom of Aparna Sen

This paper makes an attempt to understand the stardom of the Bengali film-maker and actor Aparna Sen, who has been associated with the industry for 55 years. We argue that Sen’s star persona is based on a polysemic structure, to borrow Richard Dyer’s term, which comes from the multiple roles she has played in her career. Achieving a local stardom through her work as an actor in Bengali popular cinema, she went on to acquire international fame through the films she made. Besides, as the editor of an immensely popular Bengali women’s magazine, Sen became a cultural commentator through her columns and also played an active part, through the magazine, in entering into dialogue with her readers on diverse issues such as communalism and sexuality rights. As a socially conscientious critic who has participated in several humanitarian and political causes, Sen emerged as a figure of trust and reliance for her fans and even her staunchest critics. The paper analyses the construction of her stardom, based on a series of interviews that both authors conducted with Aparna Sen over a period of time, interviews with a cross section of her fans, alongside an analysis of her media presence and finally the films she made and acted in

Local thrombolytic treatment of cerebral venous thrombosis in three paediatric patients

There is increasing evidence that local thrombolysis can be used with relative safety and efficacy in adults with superior sagittal sinus thrombosis (SSST). However, little data is available on the use of local thrombolysis in children with SSST. We report three patients who received local thrombolysis for dural sinus thrombosis. Two patients received urokinase and one patient received urokinase followed by local TPA infusion. Recanalization was achieved in two patients

Queer creative Indian city: queer film festivals, precarious cultural work and community making in Kolkata

In this article, we offer a new concept of the “queer creative city”, through a critical examination of how a regional queer Bengali film culture has emerged in Kolkata as a result of the convergence of certain urban policies, queer political organising and cultural activism. We explore two queer film festivals in Kolkata – the Siddharth Gautam Film Festival and Dialogues, both having a very significant impact in transforming LGBTQ + lives in Kolkata. Through archival research, autoethnography and conducting extensive interviews with organising committees, venue sponsors and owners, and viewers, we show how these film festivals and a pre-existing Bengali film culture engendered the emergence of a prolific creative queer city, which became a site of resistance, and community building that created a solid base for queer counterpublics. Queer film festivals, we argue, are critical sites for charting the dynamics of the public sphere in contemporary India

Nonrandomized comparison of local urokinase thrombolysis versus systemic heparin anticoagulation for superior sagittal sinus thrombosis

Background and Purpose We sought to compare the safety and efficacy of direct urokinase thrombolysis with systemic heparin anticoagulation for superior sagittal sinus thrombosis (SSST). Methods At University at Buffalo (NY) and University of Texas (Dallas, Houston), we reviewed 40 consecutive patients with SSST, treated with local urokinase (thrombolysis group) or systemic heparin anticoagulation (heparin group). The thrombolysis group (n=20) received local urokinase into the SSS followed by systemic heparin anticoagulation. The heparin group (n=20) received systemic heparin anticoagulation only. Neurological dysfunction was rated as follows: 0, normal; 1, mild (but able to ambulate and communicate); 2, moderate (unable to ambulate, normal mentation); and 3, severe (unable to ambulate, altered mentation). Results Age (P=0.49), sex (P=0.20), baseline venous infarction (P=0.73), and predisposing illnesses (P=0.52) were similar between the thrombolysis and heparin groups. Pretreatment neurological function was worse in the thrombolysis group (normal, n=5; mild, n=8; moderate, n=4; severe, n=3) than in the heparin group (normal, n=8; mild, n=8; moderate, n=3; severe, n=1) (P=NS). Discharge neurological function was better in the thrombolysis group (normal, n=16; mild, n=3; moderate, n=1; severe, n=0) than in the heparin group (normal, n=9; mild, n=6; moderate, n=5; severe, n=0) (P=0.019, Mann-Whitney U test). Hemorrhagic complications were 10% (n=2) in the thrombolysis group (subdural hematoma, retroperitoneal hemorrhage) and none in the heparin group (P=0.49). Three of the heparin group patients developed complications of the underlying disease (status epilepticus, hydrocephalus, refractory papilledema). No deaths occurred. Length of hospital stay was similar between the groups (P=0.79). Conclusions Local thrombolysis with urokinase is fairly well tolerated and may be more effective than systemic heparin anticoagulation alone in treating SSST. A randomized, prospective study comparing these 2 treatments for SSST is warranted

Effects of Systolic Blood Pressure on Brain Integrity in Multiple Sclerosis

Background: In MS patients, hypertension is associated with a delayed diagnosis and an increased risk of progression. Understanding the mechanisms of this association could potentially lead to improved prevention of disease progression. We aimed to establish whether high blood pressure contributes to white-matter injury and brain atrophy in MS.Methods: Cross-sectional study of 95 patients with RRMS. Estimates of fractional anisotropy, gray-matter volume and lesion load were obtained from 3T MRI. We used fractional anisotropy voxel-based statistics to establish the effect of blood pressure on white matter tracts. Additionally, we used voxel-based morphometry (VBM) to study the effect on gray matter integrity.Results: Only 29.5% had normal blood pressure levels, with 52.6% suffering from prehypertension and 17.9% with hypertension. Increasing systolic blood pressure was associated with damage to posterior white-matter tracts as well as greater levels of gray matter atrophy, in particular in the frontal cortex. Age-adjusted linear regression indicated that neither lesion volume (β = 0.002, 95%CI: 0.02–0.02; p = 0.85) or lesion number (β = −0.004, 95%CI: 0.03–0.02; p = 0.74) were associated with systolic blood pressure.Conclusions: Prehypertension and hypertension are frequent in MS. Increased blood pressure is related to white- and gray-matter integrity, both related to MS disability outcomes. These findings suggest attention to the control of blood pressure in MS patients

The Impact of Lesion In-Painting and Registration Methods on Voxel-Based Morphometry in Detecting Regional Cerebral Gray Matter Atrophy in Multiple Sclerosis

Background and Purpose: VBM has been widely used to study GM atrophy in MS. MS lesions lead to segmentation and registration errors that may affect the reliability of VBM results. Improved segmentation and registration have been demonstrated by WM LI before segmentation. DARTEL appears to improve registration versus the USM. Our aim was to compare the performance of VBM-DARTEL versus VBM-USM and the effect of LI in the regional analysis of GM atrophy in MS. Materials and Methods: 3T T1 MR imaging scans were acquired from 26 patients with RRMS and 28 age-matched NC. LI replaced WM lesions with normal-appearing WM intensities before image segmentation. VBM analysis was performed in SPM8 by using DARTEL and USM with and without LI, allowing the comparison of 4 VBM methods (DARTEL + LI, DARTEL − LI, USM + LI, and USM − LI). Accuracy of VBM was assessed by using NMI, CC, and a simulation analysis. Results: Overall, DARTEL + LI yielded the most accurate GM maps among the 4 methods (highest NMI and CC, P < .001). DARTEL + LI showed significant GM loss in the bilateral thalami and caudate nuclei in patients with RRMS versus NC. The other 3 methods overestimated the number of regions of GM loss in RRMS versus NC. LI improved the accuracy of both VBM methods. Simulated data suggested the accuracy of the results provided from patient MR imaging analysis. Conclusions: We introduce a pipeline that shows promise in limiting segmentation and registration errors in VBM analysis in MS

Effects of systolic blood pressure on brain integrity in multiple sclerosis

Background: In MS patients, hypertension is associated with a delayed diagnosis and an increased risk of progression. Understanding the mechanisms of this association could potentially lead to improved prevention of disease progression. We aimed to establish whether high blood pressure contributes to white-matter injury and brain atrophy in MS. Methods: Cross-sectional study of 95 patients with RRMS. Estimates of fractional anisotropy, gray-matter volume and lesion load were obtained from 3T MRI. We used fractional anisotropy voxel-based statistics to establish the effect of blood pressure on white matter tracts. Additionally, we used voxel-based morphometry (VBM) to study the effect on gray matter integrity. Results: Only 29.5% had normal blood pressure levels, with 52.6% suffering from prehypertension and 17.9% with hypertension. Increasing systolic blood pressure was associated with damage to posterior white-matter tracts as well as greater levels of gray matter atrophy, in particular in the frontal cortex. Age-adjusted linear regression indicated that neither lesion volume (β = 0.002, 95%CI: 0.02-0.02; p = 0.85) or lesion number (β = -0.004, 95%CI: 0.03-0.02; p = 0.74) were associated with systolic blood pressure. Conclusions: Prehypertension and hypertension are frequent in MS. Increased blood pressure is related to white- and gray-matter integrity, both related to MS disability outcomes. These findings suggest attention to the control of blood pressure in MS patients.Fil: Dossi, Daiana. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Chaves, Hernán. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Heck, Evelyn Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Rodriguez Murua, Sofia. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ventrice, Fernando. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Bakshi, Rohit. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Quintana, Francisco Javier. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Correale, Jorge. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Farez, Mauricio Franco. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia. Instituto de Neurociencias - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Neurociencias; Argentin