141 research outputs found
Intra‐Seasonal Variability in Sediment Provenance and Transport Processes in the Brahmaputra Basin
No full textAbstractSediment composition in modern fluvial settings is commonly assessed regarding spatial but rarely temporal variability, potentially leading to a bias of unknown extent. Here, we present the grain‐size distribution, bulk chemical and mineralogical composition of a time‐series set of 36 suspended sediment samples from the Brahmaputra river, as well as clay and heavy mineral analysis of selected samples. Sampling covers the June–November 2021 period, which included two major flooding events. We show that the two flooding events are characterized by contrasting grain size, with the first event characterized by a grain‐size minimum and the second by a grain‐size maximum. Although grain sizes of the first flood and the period after the second are similar, their compositions differ significantly, highlighted by a factor‐two decrease of biotite largely compensated by an increase in quartz. By contrast, the content of garnet, clinopyroxene, sillimanite, and rutile increased compared to epidote and amphibole during the second flood event. By relating the results to spatio‐temporal rainfall and discharge patterns and basin morphology, we conclude that the first flooding primarily mobilized hydraulically pre‐sorted sediments from the exposed sandbars of the floodplains, while those sandbars are already submerged during the second flooding in a single‐channel system, resulting in higher sediment contributions from highland tributaries draining igneous and high‐grade metamorphic rocks. Such temporal variations pose constraints on the interpretation of compositional differences between individual samples regarding sediment provenance and dispersal and should be considered in studies of modern drainage basins as well as ancient sediment routing systems.Plain Language Summary: Sediment provenance, which refers to where the sediment in a river comes from, is important to understand because it can tell us about the geology of an area, various earth‐surface processes and how the landscape is changing over time. However, sediment provenance is typically studied at a spatial scale in present day river basins, and temporal variability is rarely considered. This study examines the physical, chemical and mineralogical properties of sediment in the Brahmaputra river during two major flooding events that occurred in the same season. The results show that the sediment composition varies between the events, indicating a change in the relative proportions of distinct sources. This emphasizes the importance of considering temporal variations in sediment composition when interpreting sediment provenance signals.Key Points:
Time‐series analysis of sediment composition during two major flooding events of a single monsoon season is presented
The two flooding events show contrasting grain‐size, chemical and mineralogical composition
Temporal variations in sediment composition pose constraints on the interpretation of provenance and dispersal based on individual samples
DAADGerman Ministry of Education and Researchhttps://doi.org/10.5281/zenodo.7588054http://flood.umd.edu
Of the people, by the people, for the people: in defense of American pop culture, its meaning, and its impact
No full textAmerican pop culture has often been subjected to scorn and ridicule, both at home and abroad, often by those who view it as being immoral or who view it as not being “true” culture. This begs the questions of what exactly are the characteristics of American pop culture, why did it develop along the lines it has, and what are its sociological implications. One can examine the issue by delving into American history, and tracing how American mainstream thought has informed cultural practice. The results of such a study show that the characteristics of American pop culture were directly shaped by the ideals expressed in the American Revolution, and that American pop culture has often been at the heart of a generations-long push towards greater social freedom.M.A.Includes bibliographical referencesIncludes vitaby Avinash R. Chanda
Hand powered portable ultraviolet sterilizing water bottle with active UV dose sensing
Full text linkThesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, September 2007 [first author]; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, June 2006 [second author].Includes bibliographical references (p. 71).A portable hand powered water sterilization device was created to address a portion of the growing epidemic of global water contamination. As being more supply chain independent and having an active dose sensing component that monitors the water to insure sterilization, our device boasts far more than any current off-the-shelf devices. The device is completely hand powered via a hand crank generator. A spermicidal ultraviolet light bulb, rated at 253.7nm (UV-C), was integrated with a common NalgeneTM water bottle. Along with the bulb, UV. dose sensing electronics and a hand crank generator were incorporated as well, with the generator supplying power to both the bulb and the photodiode circuitry. Results show that eradication of common waterborne bacteria, protozoa, and viruses occurs after cranking the generator for approximately 41 seconds in clear water and up to 65 seconds in turbid water. The total weight added to the water bottle was less than a pound.by Chandan Das and Justin Holland.S.B
India’s North East and Hydropower Development
No full textHydropower, while being projected as a clean and renewable energy source, has time and again been resisted vociferously in North East India in recent times because of the obvious and unintended social and environmental impacts. The anticipated negative impacts of the associated dam and reservoir construction have cast a threat to the security of the indigenous people in terms of water, food, livelihood, energy and above all, the related socio-economic concerns. This is all the more due to the uncertainties flowing from an inadequate understanding of the possible geo-environmental impacts in a highly sensitive terrain. To cope and live with the potential negative ramifications of hydropower projects, a comprehensive hydropower policy with emphasis on long-term environmental and social security and sustainability is imperative.</jats:p
Layer-by-layer hybrid chemical doping for high transmittance uniformity in graphene-polymer flexible transparent conductive nanocomposite
Full text linkA traditional transparent conducting film (TCF) such as indium tin oxide (ITO) exhibits poor mechanical flexibility and inconsistent transmittance throughout the UV-VIS-NIR spectrum. Recent TCFs like graphene films exhibit high sheet resistance (Rs) due to defect induced carrier scattering. Here we show a unique hybrid chemical doping method that results in high transmittance uniformity in a layered graphene-polymer nanocomposite with suppressed defect-induced carrier scattering. This layer-by-layer hybrid chemical doping results in low Rs (15 sq at >90% transmittance) and 3.6% transmittance uniformity (300-1000 nm) compared with graphene (17%), polymer (8%) and ITO (46%) films. The weak localization effect in our nanocomposite was reduced to 0.5%, compared with pristine (4.25%) and doped graphene films (1.2%). Furthermore, negligible Rs change (1.2 times compared to 12.6 × 103 times in ITO) and nearly unaltered transmittance spectra were observed up to 24 GPa of applied stress highlighting mechanical flexibility of the nanocomposite film. © 2018 The Author(s
Knowledge-based cluster development in India : opportunities and challenges
Full text linkThesis (S.M. in Real Estate Development)--Massachusetts Institute of Technology, Dept. of Architecture, Center for Real Estate, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 89-92).Knowledge-based industries tend to cluster. The nature of activities illustrate the importance of networks and virtual and proximity aspects of clustering. Review of existing literature brings out the advantages of clustering for such industries. The purpose of the study is to comprehend the current status of development, both economic and real estate, in the knowledge-based industries in India. A stylized model is used as a reference to understand the status of economic development. Current body of literature and interview results from this study suggests transitioning nature of India's knowledge-based industry from being a services provider to becoming a knowledge provider. However, there are challenges in the transition process related to infrastructure and human resource. This study suggests that a large scale mixed use project may in fact be able to address some of the ongoing issues in the economic domain. The proposed development may lead to clustering of business and universities thus, giving rise to a knowledge-based cluster in India.by Chandan Dev Singla.S.M.in Real Estate Developmen
Evaluation of arsenic adsorption capacity of indigenous materials for their suitability as filter media
No full textClimate Change Impact on the Southwest Monsoon Modulated Freshwater Pulsation and Consequent Nutrient Flux Variability in the Continental Shelf of the Northern Indian Ocean
No full textSediment Dynamics in a Large Alluvial River: Characterization of Materials and Processes and Management Challenges
No full textAesoper Galpa Samagra (Aesop's Fables: Bengali)
No full textHere is a genuine find in this sense: I found it without help on the shelves in this fine bookshop near St. Xavier's College in Kolkata. The picture on the cover, including a fox and some grapes, gave me the clue. It is my first book exclusively in Bengali; I have a bilingual copy of Fox Fables that has both Bengali and English. This book features about a dozen full-page black-and-white designs. Among the best of them are The Ethiopian and CW. I cannot give page numbers because those too are in Bengali! I am proud of finding this book on my busy day in Kolkata!This is a hardbound book (hard cover)Language note: BengaliRetold by Naresh Chandra Jan
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