Showing 1761 - 1770 of 5709 Items
General Catalogue of Bowdoin College and the Medical School of Maine: A Biographical Record of Alumni and Officers, 1794-1950
Date: 1950-01-01
Access: Open access
- General Catalogue of Bowdoin College and the Medical School of Maine: A Biographical Record of Alumni and Officers, 1794-1950 (1950) provides a complete and comprehensive biographical record of all of Bowdoin’s students, faculty, and administrative officers from the founding of the College in 1794 through 1950.
Monteverde: Ecology and Conservation of a Tropical Cloud Forest
Date: 2000-01-01
Creator: Nalini M. Nadkarni, Nathaniel T. Wheelwright
Access: Open access
- The Monteverde Cloud Forest Reserve has captured the worldwide attention of biologists, conservationists, and ecologists and has been the setting for extensive investigation over the past 40 years. Roughly 40,000 ecotourists visit the Cloud Forest each year, and it is often considered the archetypal high-altitude rain forest. Featuring synthetic chapters and specific accounts written by more than 100 biologists and local residents, the 573-page book documents in a single volume everything known about the biological diversity of Monteverde, Costa Rica, and how to protect it. New short chapters which update and expand the research presented in the 2000 Oxford publication were written in 2014 and are now available.
Bilateral consequences of chronic unilateral deafferentation in the auditory system of the cricket gryllus bimaculatus
Date: 2011-04-01
Creator: Hadley Wilson Horch, Elizabeth Sheldon, Claire C. Cutting, Claire R. Williams, Dana M., Riker, Hannah R. Peckler, Rohit B. Sangal
Access: Open access
- The auditory system of the cricket has the unusual ability to respond to deafferentation by compensatory growth and synapse formation. Auditory interneurons such as ascending neuron 2 (AN-2) in the cricket Gryllus bimaculatus possess a dendritic arbor that normally grows up to, but not over, the midline of the prothoracic ganglion. After chronic deafferentation throughout larval development, however, the AN-2 dendritic arbor changes dramatically, and medial dendrites sprout across the midline where they form compensatory synapses with the auditory afferents from the contralateral ear. We quantified the extent of the effects of chronic, unilateral deafferentation by measuring several cellular parameters of 3 different neuronal components of the auditory system: the deafferented AN-2, the contralateral (or nondeafferented) AN-2 and the contralateral auditory afferents. Neuronal tracers and confocal microscopy were used to visualize neurons, and double-label experiments were performed to examine the cellular relationship between pairs of cells. Dendritic complexity was quantified using a modified Sholl analysis, and the length and volume of processes and presynaptic varicosities were assessed under control and deafferented conditions. Chronic deafferentation significantly influenced the morphology of all 3 neuronal components examined. The overall dendritic complexity of the deafferented AN-2 dendritic arbor was reduced, while both the contralateral AN-2 dendritic arbor and the remaining, intact, auditory afferents grew longer. We found no significant changes in the volume or density of varicosities after deafferentation. These complex cellular changes after deafferentation are interpreted in the light of the reported differential regulation of vesicle-associated membrane protein and semaphorin 2a. Copyright © 2011 S. Karger AG, Basel.
Sri Lanka in 2017: Sluggish on many fronts
Date: 2018-01-01
Creator: Sree Padma
Access: Open access
- Sri Lanka's 69-year-old parliamentary democracy continues with power concentrated at the center, and consequently, the country's non-Sinhala-Buddhist minorities on the periphery continue to press for equal rights, while ethnic strife hinders prospects for unified progress. Maithripala Sirisena, president since 2015, promises reconciliation but has received little cooperation from the majority Sinhala Buddhists.
Baroque Paintings from the Collection of Walter P. Chrysler, Jr.
Date: 1963-01-01
Access: Open access
- This catalogue is in lieu of Bulletin vol. II: no. 3.
Geochemical and Stratigraphic Analysis of the Linnévatnet Sediment Record: A Study of Late Holocene Cirque Glacier Activity in Spitsbergen, Svalbard
Date: 2014-05-01
Creator: Graham Harper Edwards
Access: Open access
- Morainal and lacustrine sediments in Linnédalen, Spitsbergen, Svalbard, record the fluctuations of a glacier in a currently unglaciated mountain cirque during the Little Ice Age (LIA). This study attempts to reconstruct Late Holocene glacial activity within this cirque from geochemical, physical, and visual stratigraphic variation of the Linnévatnet lacustrine sediment record. A 57 cm lacustrine sediment core (D10.5) from Linnévatnet was analyzed at a high-resolution for variations in X-Ray Fluorescence (XRF)-measured elemental composition, spectral reflectance, and magnetic susceptibility. The visual stratigraphy was observed at a microscopic scale. An age-depth model for D10.5 is developed by extrapolating sedimentation rates from dated horizons, measured by 239+240Pu radionuclide fallout dating and chemostratigraphic enrichment of atmospheric anthropogenic pollutants. Visual stratigraphy of the sediment record indicates two periods of cirque glacier sediment delivery to Linnévatnet during the LIA (1329-1363 CE, 1816 CE-Present) and a third period of sediment delivery during the Medieval Climate Anomaly (MCA; 984-1082 CE). During non-glacial periods, stratigraphic variation in XRF-measured Ti and K appear to be associated with fluctuations in North Atlantic Oscillation (NAO)-regulated precipitation. Within the LIA glacial intervals, decadal-scale variations in sediment Ti and K geochemistry may result from advance and retreat of the cirque glacier ice-margin or fluctuations in precipitation. Stratigraphic variation in Fe content indicates complex erosional and hydrological processes associated with MCA precipitation and glacial meltwater. Stratigraphic and geochemical variations in the lacustrine record of Linnévatnet indicate that both cirque glacier activity and sediment transport in Linnédalen are more sensitive to climatological change than previously thought.
Teaching Computers to Teach Themselves: Synthesizing Training Data based on Human-Perceived Elements
Date: 2019-05-01
Creator: James Little
Access: Open access
- Isolation-Based Scene Generation (IBSG) is a process for creating synthetic datasets made to train machine learning detectors and classifiers. In this project, we formalize the IBSG process and describe the scenarios—object detection and object classification given audio or image input—in which it can be useful. We then look at the Stanford Street View House Number (SVHN) dataset and build several different IBSG training datasets based on existing SVHN data. We try to improve the compositing algorithm used to build the IBSG dataset so that models trained with synthetic data perform as well as models trained with the original SVHN training dataset. We find that the SVHN datasets that perform best are composited from isolations extracted from existing training data, leading us to suggest that IBSG be used in situations where a researcher wants to train a model with only a small amount of real, unlabeled training data.
Economic Analysis of the Critical Habitat Designation Process for Endangered and Threatened Species Under the Endangered Species Act of 1973
Date: 2022-01-01
Creator: Katherine Fosburgh
Access: Open access
- Habitat destruction is the leading cause of biodiversity loss in the US. Under the Endangered Species Act (ESA), habitat deemed essential to endangered and threatened species recovery is proposed as critical habitat (CH). CH areas are subject to regulations that could alter land development plans or increase costs. The potential economic opportunity cost created by CH regulations may lead to the exclusion of land proposed for CH designation, thereby reducing the conservation benefits of the CH rule. In this paper, I use a unique dataset collected from Federal Register (FR) documents to estimate the reduction in CH acreage from proposed to final ruling, both on the extensive and intensive margin. I find a negative relationship between the level of household income in an area proposed for CH and the probability that a CH gains acreage or maintains acreage during the establishment process. I also find some evidence that higher household income in a CH area is associated with a greater relative loss in acreage between proposal and finalization. I also find that private land proposed for CH designation is less likely to be in the final designation than federal land. Overall, my results suggest that economic considerations influence CH allocation decisions. Whether reducing the amount of private land subject to CH designations is socially efficient depends on the unknown economic benefit of private land exclusions versus the cost of biodiversity and ecosystem service loss that may result from not protecting all land deemed vital to species recovery.