210 research outputs found
Fine-scale spatial and temporal acoustic occurrence of island-associated odontocetes near a mid-oceanic atoll in the northern Indian Ocean
No full text© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Panicker, D., Baumgartner, M. F., & Stafford, K. M. Fine-scale spatial and temporal acoustic occurrence of island-associated odontocetes near a mid-oceanic atoll in the northern Indian Ocean. Marine Ecology Progress Series, 683, (2022): 195–208, https://doi.org/10.3354/meps13947.Temporal patterns of oceanic predators can provide valuable information on both lunar and diel influences not just on the distributions of these predators, but also on prey patches that are often difficult to study. Mid-oceanic island chains in the northern Indian Ocean have high odontocete occurrence, but the ecology of these animals is not well characterized. We investigated fine-scale spatial and temporal patterns of island-associated odontocetes using passive acoustic monitoring from January 2019 to January 2020 around Kavaratti Island, Lakshadweep, India. Based on opportunistic recordings in the presence of odontocetes, the majority of the detected whistles were likely made by spinner dolphins Stenella longirostris. We identified a resident population whose whistle occurrence was significantly influenced by month, site, and diel and lunar cycles. More acoustic detections were made in the northeast monsoon month of November and fewer during pre-monsoon and southwest monsoon periods. Distinct day-night differences along with fine-scale temporal variability were also observed, suggesting that delphinids use nearshore waters as a daytime resting habitat. Odontocete detections were highest during the new moon period and lowest during the first quarter phase. Detection rates were higher on the south side of the island. Our study shows that solar and lunar cycles modulate odontocete vocal occurrence, presumably through influences on their prey. Similarities of odontocete occurrence around Lakshadweep to other mid-oceanic island chains suggests that an island-associated micronekton community may exist around Lakshadweep that may also be important to other pelagic species targeted by local fisheries.Funding was provided by the Office of Naval Research Marine Mammal Biology Program, USA, under grant N000141812795.
We thank Ajith Kumar, the National Centre for Biological Sciences and Idrees Babu for in-country support
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
Data: Cetacean Distribution and Diversity in Lakshadweep Waters, India Using a Platform of Opportunity: Oct 2015 to Apr 2016
No full textUnderstanding cetacean community composition and distribution in Lakshadweep waters, Northern Indian Ocean
No full textThesis (Ph.D.)--University of Washington, 2022The Northern Indian Ocean (NIO) is a region of high environment variability driven by seasonally reversing winds. The southwest monsoons generate substantial plankton blooms in these tropical waters and shape biogeography of higher trophic levels. Cetaceans in oceanic waters are good indicators of epipelagic and mesopelagic prey bases. This dissertation examines species composition and distribution of cetaceans in a mid-oceanic island habitat in southeastern Arabian Sea. I use passive acoustic monitoring (PAM), which is particularly useful to collect data year-round including night periods and the rough-weather southwest monsoon season when visual surveys are challenging. In Chapter 2, I examine the occurrence and species composition of the cetacean community in the Lakshadweep archipelago via visual surveys using a platform of opportunity. The surveys documented 139 sightings, including eight odontocete species and one mysticete species. Occurrence of cetacean species differed across seafloor slope gradients and distances to nearest landmass. In Chapter 3, I investigate baleen whale occurrence in Lakshadweep waters using PAM. The study showed occurrence of Central Indian Ocean (CIO; formerly Northern Indian Ocean) acoustic population of blue whales in Indian waters. These results extend the known range of CIO pygmy blue whales about 1000 km north-westward from the waters surrounding Sri Lanka. In Chapter 4, I determined the occurrence and temporal patterns of island-associated odontocetes in Lakshadweep waters using PAM. A resident population, likely to be spinner dolphins, was identified. Whistle occurrence was significantly influenced by month, site, and diel and lunar cycles. Similarities of odontocete occurrence to other mid-oceanic island chains suggest that an island-associated micronekton community may exist around Lakshadweep. In Chapter 5, I characterize dominant sound sources to the shallow water reef soundscape in Lakshadweep and their correlation with local oceanographic parameters across monsoon and non-monsoon months. Four acoustic bands of interest, namely a geophonic band of wind-driven wave sounds and three biophonic bands containing animal choruses, are presented. Low frequency biophonic choruses peaked in inter-monsoon months, while low frequency geophonic sound levels peaked during monsoon months. Choruses showed site-wise variability and correlation with sea surface salinity, chlorophyll-a, and wind speed. Understanding cetaceans and the underwater soundscape through an oceanographic lens highlight the underlying biological resources and physical drivers in this poorly studied area. This dissertation demonstrates that employing appropriate technology and methodologies can shed light on even highly mobile species (such as blue whales) in challenging conditions. Within the context of a changing climate, the information presented here can provide a baseline to compare with future cetacean and soundscape studies in this region. Furthermore, the dissertation emphasizes that current plans for tourism development in these islands need to incorporate potential impacts on near-island cetacean communities and on underwater noise
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
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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