215 research outputs found
CTX DTM and ORI Mosaics over Sakarya Vallis, Gale Crater, Mars
No full textLocal digital terrain model (DTM) and orthorectified image (ORI) mosaics over Sakarya Vallis, west of Aeolis Mons in Gale crater, Mars. The two constituent DTMs were processed using the CASP-GO suite described in Tao et al. (2018); the ORIs were processed using Ames Stereo Pipeline. The DTMs were then co-registered to an HRSC DTM mosaic (Persaud et al. 2021, https://doi.org/10.5281/zenodo.5808354) and each other using Ames Stereo Pipeline, and then cropped and mosaicked.
Format: GeoTiff
Projection: Equidistant cylindrical
Datum: Spheroid (r = 3396.190 km)
Bit depth: Float32
DTM grid-spacing: 18 m/pixel
ORI resolution: 6 m/pixel
Stereo pairs (from Grindrod and Davis, 2018):
P04_002675_1746_XI_05S222W, B21_017786_1746_XN_05S222W
D02_027834_1748_XN_05S222W, G04_019698_1747_XI_05S222W
Image IDs of the ORIs: P04_002675_1746_XI_05S222W, D02_027834_1748_XN_05S222WThe first author is now at Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California. Contact: [email protected]
Merchants of Virtue
No full textMerchants of Virtue explores the question of what it meant to be Hindu in precolonial South Asia. Divya Cherian presents a fine-grained study of everyday life and local politics in the kingdom of Marwar in eighteenth-century western India to uncover how merchants enforced their caste ideals of vegetarianism and bodily austerity as universal markers of Hindu identity. Using legal strategies and alliances with elites, these merchants successfully remade the category of “Hindu,” setting it in contrast to “Untouchable” in a process that reconfigured Hinduism in caste terms. In a history pertinent to understanding India today, Cherian establishes the centrality of caste to the early-modern Hindu self and to its imagination of inadmissible others.
“A refreshingly different perspective on the history of caste and untouchability in India, enlarging the field of scholarship from its focus on the colonial era by telling us how precolonial configurations of power in the locality shaped the everyday experience of caste.” — GOPAL GURU, coauthor of The Cracked Mirror and Experience, Caste, and the Everyday Social
“This provocative and empirically rich study offers a plenitude of fascinating insights into aspects of western Indian history ca. 1800, from kingship and caste hierarchy to abortion and alcohol consumption. Particularly innovative is its focus on the critical role played by merchants in articulating social identities that became widespread in modern times.” — CYNTHIA TALBOT, author of The Last Hindu Emperor
“A pathbreaking book that explodes essentialist views of the construction of Hindu and Muslim identities in precolonial India. Divya Cherian provocatively argues that the category of ‘Hindu’ was the primary locus for a system of radical othering that excluded Untouchables (and Muslims as Untouchables) through mechanisms of state, law, and everyday life.” — CHRISTIAN LEE NOVETZKE, Professor of South Asian and Religious Studies, University of Washingto
Merchants of Virtue
No full textMerchants of Virtue explores the question of what it meant to be Hindu in precolonial South Asia. Divya Cherian presents a fine-grained study of everyday life and local politics in the kingdom of Marwar in eighteenth-century western India to uncover how merchants enforced their caste ideals of vegetarianism and bodily austerity as universal markers of Hindu identity. Using legal strategies and alliances with elites, these merchants successfully remade the category of “Hindu,” setting it in contrast to “Untouchable” in a process that reconfigured Hinduism in caste terms. In a history pertinent to understanding India today, Cherian establishes the centrality of caste to the early-modern Hindu self and to its imagination of inadmissible others.
“A refreshingly different perspective on the history of caste and untouchability in India, enlarging the field of scholarship from its focus on the colonial era by telling us how precolonial configurations of power in the locality shaped the everyday experience of caste.” — GOPAL GURU, coauthor of The Cracked Mirror and Experience, Caste, and the Everyday Social
“This provocative and empirically rich study offers a plenitude of fascinating insights into aspects of western Indian history ca. 1800, from kingship and caste hierarchy to abortion and alcohol consumption. Particularly innovative is its focus on the critical role played by merchants in articulating social identities that became widespread in modern times.” — CYNTHIA TALBOT, author of The Last Hindu Emperor
“A pathbreaking book that explodes essentialist views of the construction of Hindu and Muslim identities in precolonial India. Divya Cherian provocatively argues that the category of ‘Hindu’ was the primary locus for a system of radical othering that excluded Untouchables (and Muslims as Untouchables) through mechanisms of state, law, and everyday life.” — CHRISTIAN LEE NOVETZKE, Professor of South Asian and Religious Studies, University of Washingto
Improved collision detection in StarLogo Nova
No full textThesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (page 65).StarLogo Nova is blocks-based educational software that allows students to write and play their own 3D games online. It is the online version of StarLogo TNG. This thesis explores the problem of needing more accurate collision detection in StarLogo Nova while maintaining reasonable performance. Three new collision detection systems for StarLogo Nova are developed and evaluated. Compared to the spheres used to perform collision checks in the current system, the first new system, called the TightestFitCollider, introduces a variety of bounding spheres, bounding boxes, and bounding capsules as bounding structures that may fit the models in StarLogo Nova more closely. The second system, called the HierarchicalCollider, uses hierarchies of bounding boxes to perform even more precise collision detection than the TightestFitCollider. Finally, the third system combines the first two systems, so that the advantages of each can be used as appropriate. The three systems are evaluated for their accuracy and performance within the StarLogo Nova framework.by Divya Bajekal.M. Eng
Antiepileptic drugs for the primary and secondary prevention of seizures after subarachnoid haemorrhage
No full textBackground: subarachnoid haemorrhage may result in seizures both acutely and in the longer term. The use of antiepileptic drugs (AEDs) in the primary and secondary prevention of seizures after subarachnoid haemorrhage is uncertain, and there is currently no consensus on treatment.Objectives: to assess the effects of AEDs for the primary and secondary prevention of seizures after subarachnoid haemorrhage.Search methods: we searched the Cochrane Epilepsy Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 1) in The Cochrane Library, and MEDLINE (1946 to 12th March 2013). We checked the reference lists of articles retrieved from these searches.Selection criteria: we considered all randomised and quasi-randomised controlled trials in which patients were assigned to a treatment (one or more AEDs) or placebo.Data collection and analysis: two review authors (RM and JK) independently screened and assessed the methodological quality of the studies. If studies were included, one author extracted the data and the other checked it.Main results: no relevant studies were found.Authors' conclusions: there was no evidence to support or refute the use of antiepileptic drugs for the primary or secondary prevention of seizures related to subarachnoid haemorrhage. Well-designed randomised controlled trials are urgently needed to guide clinical practice
On Multi-Resolution 3D Orbital Imagery and Visualisation for Mars Geological Analysis
No full textMars Science Laboratory has revealed a dynamic history of water as the rover has ascended the mysterious Mount Sharp in Gale crater. Because rovers only “see” their local environment, planetary scientists rely on satellite-based orbital imagery to understand the regional geology of Gale crater. However, orbital imagery is map-view—viewed from above, lacking perspective—which presents challenges to interpretation of stratigraphy.
3D visualisation is an emerging opportunity to study orbital images in more intuitive, field-like environments, but has had limited application to Mars. In this work, I formulate and analyse 3D orbital imagery over Gale crater, Mars to investigate the stratigraphy of Mount Sharp 700 m above and 40 km away from MSL. First, I process orbital imagery from the HRSC, CTX, and HiRISE cameras into 3D digital terrain models (DTMs). I then co-register and evaluate these DTMs using statistical tools and existing products to build a new, validated, multi-resolution basemap tied down to MOLA.
Sakarya Vallis, a 400-m deep canyon on Mount Sharp, was then analysed in a 3D environment at 1 m/px. From measurements of exposed rock layers, I construct cross-sections, stratigraphic logs, and a geological unit map to capture this geology. Seven geological units are interpreted across 1 km of exposure, varying in thicknesses (10–174 m) and dips (3–12º). These units may reveal a cyclic depositional environment; a progradational sequence and channel; and unconformities. This work therefore suggests two periods of sub-aqueous deposition in this region during the Late Noachian to Early Hesperian. These results further provide geological context of Gale crater as MSL ascends Mount Sharp, and future inputs for palaeoenvironmental models of Gale crater
Morpho-Stratigraphy of Sakarya Vallis, Gale Crater, Mars: A Virtual Outcrop Study
No full textSakarya Vallis is a 26-km-long, up to 3.5-km-wide, and up to 450-m-deep feature that cross-cuts the northwest of Mount Sharp in Gale crater, Mars. The center of the canyon is ~30 km from and 700 m higher in elevation than the approximate location of the Mars Science Laboratory (MSL) and exposes the upper Lower mound formation of the Mount Sharp group. Analysis of this immense outcrop can provide insight into the extents and geometries of these rock layers, contribute to understanding of the stratigraphy of Gale crater, and help to inform depositional models of these strata and the formation of Mount Sharp.
We present morpho-stratigraphic interpretations from a 3D HiRISE scene visualized and analyzed as a 400-m-thick, 15-km-long digital outcrop in the 3D visualization environment PRo3D. Seven primary units (packages 1–7) were identified from the exposed stratigraphy based on their visible morphologies, such as bedding styles, key features, sub-packages, and bounding surfaces. Stratigraphic logs and cross-sections were constructed at eleven sites throughout the canyon, derived from topographic profiles and measured layer thicknesses and dips and dip directions (e.g., Fig. 1). Finally, these interpretations were extrapolated over a basemap of the northwest Mt. Sharp, and compared with units identified in other works alongside insight from CRISM.
Four packages exhibit morphologies and bedding geometries that may indicate aqueous deposition or otherwise problematize a layer-cake model for the Lower mound formation: a progradational sequence; cyclic bedding; an unconformity; and a lens feature. The package bounding surfaces overwhelmingly dip to the west and northwest, consistent with other works, while internal layers vary. Initial CRISM analysis reveals monohydrated and polyhydrated sulfates, along with low-Ca pyroxene dust, exposed in Sakarya Vallis, while Package 3 is likely a mix of sulphates and other hydrated mineralogy.
We also present a commentary on both automated and manual image processing techniques and how they affect digital outcrop measurements, with relevance to future 3D studies in this field. It is observed that at changes in slope, slight shifts between the overlying imagery and the terrain data can generate uncertainty in layer boundaries, and this will affect dip/dip-direction measurements
Space Science in Context: Lessons Learned and Recommendations for IDEA Practice and Beyond
No full textNo abstract available
30-m HRSC DTM Mosaic of Gale Crater, Mars
No full textDigital terrain model (DTM) mosaic of Gale crater, Mars, processed from High-Resolution Stereo Camera (HRSC) stereo images using the modification of DLR-VICAR described by Kim and Muller (2009).
Format: GeoTiff
Projection: Equidistant cylindrical
Datum: Spheroid (r = 3396.190 km)
Bit depth: Float32
Grid-spacing: 30 m/pixel
Terrain reference: 200-m MOLA and HRSC blended global DTM (Fergason et al. 2018)
HRSC source images: H1938_0000, H1927_0000, and H1916_0000The first author is now at Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California. Contact: [email protected]
Magnetic resonance imaging of the cerebral metabolic rate of oxygen (CMRO₂)
No full textThesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 120-128).Oxygen consumption is an essential process of the functioning brain. The rate at which the brain consumes oxygen is known as the cerebral metabolic rate of oxygen (CMRO₂). CMRO₂ is intimately related to brain health and function, and will change in settings of disease and functional activation. Accurate CMRO₂ measurement will enable detailed investigation of neuropathology and facilitate our understanding of the brain's underlying functional architecture. Despite the importance of CMRO₂ in both clinical and basic neuroscience settings, a robust CMRO₂ mapping technique amenable to functional and clinical MRI has not been established. To address this issue, a novel method called QUantitative Imaging of eXtraction of Oxygen and TIssue Consumption, or QUIXOTIC, is introduced. The key innovation in QUIXOTIC is the use of velocity-selective spin labeling to isolate MR signal exclusively from post-capillary venular blood on a voxel-by-voxel basis. This isolated signal can be related to venular oxygen saturation, oxygen extraction fraction, and ultimately CMRO₂. This thesis first explores fundamental theory behind the QUIXOTIC technique, including design of a novel MRI pulse sequence, explanation of the principal sequence parameters, and results from initial human experiences. A human trial follows, in which QUIXOTIC is used to measure cortical gray matter CMRO₂ in ten healthy volunteers.(cont.) QUIXOTIC-measured CMRO₂ is found to be within the expected physiological range and is comparable to values reported by other techniques. QUIXOTIC is then applied to evaluate CMRO₂ response to carbon-dioxide-induced hypercapnia in awake humans. In this study, CMRO₂ is observed to decrease in response to mild hypercapnia. Finally, pilot studies that show feasibility of QUIXOTIC-based functional MRI (fMRI) and so-called "turbo" QUIXOTIC are presented and discussed.by Divya Sanam Bolar.Ph.D
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