Colby College
  • United States
Recent publications
The analyses of axial and lateral capacity of a pile are significantly dependent on the appropriate estimation of scour depth, while the scour depth estimation procedure is uncertain due to the hydraulic, hydrologic, and geotechnical parameters uncertainty. Work herein is focused on developing a framework for reliability-based pier scour assessment methodology and demonstrate its integration with the concept of Load and Resistance Factor Design (LRFD) approach. Scour factors are proposed based on reliability level (β) and the associated probability of deceedance (POD). Three example applications of axially and laterally loaded pile design approach while including scour factor in the LRFD framework are demonstrated. Based on axial pile capacity analysis, the increase of pile length when the β-based scour assessment is used with the soil resistance factors, was estimated to be 26.5–29.6 % higher compared to using the deterministic scour with soil resistance factor. In the case of lateral pile response analysis, as β is increased from 2.0 to 3.0, the lateral pile head deflection increased by 46–132 % compared to the deterministically-estimated scour depth case. To obtain β= 3.0 for the considered example while maintaining the pile length unchanged, the pile diameter needed to be increased by 35.7 % compared to the base case pile’s diameter.
Gas- and particle-phase molecular markers provide highly specific information about the sources and atmospheric processes that contribute to air pollution. In urban areas, major sources of pollution are changing as regulation selectively mitigates some pollution sources and climate change impacts the surrounding environment. In this study, a comprehensive thermal desorption aerosol gas chromatograph (cTAG) was used to measure volatile, intermediate-volatility and semivolatile molecular markers every other hour over a 10 d period from 11 to 21 April 2018 in suburban Livermore, California. Source apportionment via positive matrix factorization (PMF) was performed to identify major sources of pollution. The PMF analysis identified 13 components, including emissions from gasoline, consumer products, biomass burning, secondary oxidation, aged regional transport and several factors associated with single compounds or specific events with unique compositions. The gasoline factor had a distinct morning peak in concentration but lacked a corresponding evening peak, suggesting commute-related traffic emissions are dominated by cold starts in residential areas. More monoterpene and monoterpenoid mass was assigned to consumer product emissions than biogenic sources, underscoring the increasing importance of volatile chemical products to urban emissions. Daytime isoprene concentrations were controlled by biogenic sunlight- and temperature-dependent processes, mediated by strong midday mixing, but gasoline was found to be the dominant and likely only source of isoprene at night. Biomass burning markers indicated residential wood burning activity remained an important pollution source even in the springtime. This study demonstrates that specific high-time-resolution molecular marker measurements across a wide range of volatility enable more comprehensive pollution source profiles than a narrower volatility range would allow.
Comparative structural neuroanatomy is a cornerstone for understanding human brain structure and function. A parcellation framework that relates systematically to fundamental principles of histological organization is an essential step in generating structural comparisons between species. In the present investigation, we developed a comparative parcellation reasoning system (ComPaRe), which is a formal ontological system in human and non-human primate brains based on the cortical cytoarchitectonic mapping used for both species as detailed by Brodmann. ComPaRe provides a theoretical foundation for mapping neural systems in humans and other species using neuroimaging. Based on this approach, we revised the methodology of the original Harvard-Oxford Atlas (HOA) system of brain parcellation to produce a comparative framework for the human (hHOA) and the rhesus monkey (mHOA) brains, which we refer to as HOA2.0-ComPaRe. In addition, we used dedicated segmentation software in the publicly available 3D Slicer platform to parcellate an individual human and rhesus monkey brain. This method produces quantitative morphometric parcellations in the individual brains. Based on these parcellations we created a representative template and 3D brain atlas for the two species, each based on a single subject. Thus, HOA2.0-ComPaRe provides a theoretical foundation for mapping neural systems in humans and other species using neuroimaging, while also representing a significant revision of the original human and macaque monkey HOA parcellation schemas. The methodology and atlases presented here can be used in basic and clinical neuroimaging for morphometric (volumetric) analysis, further generation of atlases, as well as localization of function and structural lesions.
Mastery goal structures, which communicate value for developing deeper understanding, are an important classroom support for student motivation and engagement, especially in the context of science learning aligned with the Next Generation Science Standards. Prior research has identified key dimensions of goal structures, but a more nuanced examination of the variability of teacher-enacted and student-perceived goal structures within and across classrooms is needed. Using a concurrent mixed-methods approach, we developed case studies of how three 7th-grade science teachers enacted different goal structures while teaching the same chemistry unit and how their students perceived these goal structures. Student perceptions were largely consistent with our observational analysis and suggested that a positive social climate and autonomy support are important elements of mastery goal structure. However, balancing socio-emotional support with sufficient academic rigor may be especially important for students with high levels of mastery goal orientation and self-efficacy in science. Implications for research include the need for further research linking classroom stimuli to variability in perceived goal structure, especially across students with different motivational characteristics. Implications for practice include strategies for science teachers to promote perceptions of a mastery goal focus in students, particularly through feedback and recognition practices.
This Element examines the eighteenth-century novel's contributions to empirical knowledge. Realism has been the conventional framework for treating this subject within literary studies. This Element identifies the limitations of the realism framework for addressing the question of knowledge in the eighteenth-century novel. Moving beyond the familiar focus in the study of novelistic realism on problems of perception and representation, this Element focuses instead on how the eighteenth-century novel staged problems of inductive reasoning. It argues that we should understand the novel's contributions to empirical knowledge primarily in terms of what the novel offered as training ground for methods of reasoning, rather than what it offered in terms of formal innovations for representing knowledge. We learn from such a shift that the eighteenth-century novel was not a failed experiment in realism, or in representing things as they are, but a valuable system for reasoning and thought experiment.
Central to climate justice is the question of who will pay for the mitigation and adaptation efforts needed as the climate crisis worsens, particularly in countries that bear little responsibility for global greenhouse gas emissions. Climate finance is a complex set of mechanisms intended to address this concern. World-systems theory has long understood international development assistance as a tool that reproduces spatial dependency between states. In this paper, we ask whether climate finance follows the expectations of world-systems theory and reproduces relationships of dependency, or if it instead advances climate justice and challenges spatial dependency in the world-system. Through this analysis, we consider the implications of climate finance for world-systems theory. We use recent empirical data to ask whether climate finance follows or challenges world-systems theory expectations, focusing on five areas: (1) spatial flows of climate finance between the core, semi-periphery, and periphery; (2) the governance of climate finance institutions; (3) the types of projects supported by climate finance; (4) the relationship of projects to dominant systems of extraction, production, and consumption; and (5) the agency of peripheral state and non-state actors in shaping climate finance in relation to their interests. Taken together, we argue that climate finance in many ways reproduces relationships of dependency, though potential avenues exist for contesting this unequal balance of power and for advocating for climate justice. This case illustrates the need to approach analyses of dependency in a nuanced way, interrogating specific processes through which dependency is produced and contested across scales.
The local (central) limit theorem precisely describes the behavior of iterated convolution powers of a probability distribution on the d-dimensional integer lattice, Zd. Under certain mild assumptions on the distribution, the theorem says that the convolution powers are well-approximated by a single scaled Gaussian density which we call an attractor. When such distributions are allowed to take on complex values, their convolution powers exhibit new and striking behaviors not seen in the probabilistic setting. Following works of I. J. Schoenberg, T. N. E. Greville, P. Diaconis, and L. Saloff-Coste, the author and L. Saloff-Coste provided a complete description of local limit theorems for the class of finitely supported complex-valued functions on Z. For convolution powers of complex-valued functions on Zd, much less is known. In a previous work by the author and L. Saloff-Coste, local limit theorems were established for complex-valued functions whose Fourier transform is maximized in absolute value at so-called points of positive homogeneous type and, in that case, the resultant attractors are generalized heat kernels corresponding to a class of higher order partial differential operators. By considering the possibility that the Fourier transform can be maximized in absolute value at points of imaginary homogeneous type, a notion motivated by V. Thomée, this article extends previous work of the author and L. Saloff-Coste to broaden the class of complex-valued functions for which it is possible to obtain local limit theorems. These local limit theorems contain attractors given by certain oscillatory integrals and their convergence is established using a generalized polar-coordinate integration formula, due to H. Bui and the author, and the Van der Corput lemma. The article also extends recent results on sup-norm type estimates of H. Bui and the author.
Charred fossils from the Wenlock (Wales) and Ludlow (Poland) are evidence of the earliest wildfires to date, showing this phenomenon was contemporaneous with the earliest records of land plant macrofossils. These data indicate fires began to influence Earth system processes alongside those wrought by the advent of an embryophytic terrestrial flora. By the mid-Silurian, fires affected atmospheric composition, sedimentary systems, carbon-and-nutrient cycling, landscape diversity, community composition, and species interactions. As global-heating alters wildfire regimes, greater recognition is being given to fires and their ecosystem impacts, a relationship we now know extends back >430 million years. Here we document the taxonomic composition of charred phytoclasts, evidence of wildfire activity, from two discrete Silurian localities–the Pen-y-lan Mudstone, Rumney, Wales, and the Winnica Formation, Holy Cross Mountains, Poland. Nematophytes dominate each mesofossil assemblage and quantitative reflectance data indicate generally low-temperature fires at both sites, but with locally intense conditions. These and other Silurian assemblages, herein documented as bearing-charcoal, are used to evaluate the systematics, fuel load, and burn temperatures of these earliest wildfires. We propose a diagrammatic reconstruction to explain the seeming disparity between the diminutive size of the embryophytic biota and the highest temperatures (>700˚ C) recorded in these charcoals. Supplementary material: [Raw Mean Random Reflectance (R o %) data from Rumney Borehole, Winnica, Ludford Lane and North Brown Clee Hill sorted by both Locality and Morphotype] is available at: https://doi.org/10.6084/m9.figshare.c.6179309
Comprehensive and meaningful inclusion of marginalized communities within the research enterprise will be critical to ensuring an equitable, technology-informed, clean energy transition. We provide five key action items for government agencies and philanthropic institutions to operationalize the commitment to an equitable energy transition.
Post-millennial Tamil cinema has seen a marked increase in casting women as protagonists or in pivotal roles. In a historically patriarchal industry that rests on an almost sycophantic male star system, this proliferation of women characters has proven significant in expanding the possibilities of female stardom. In turn, the potential of women stars and women’s narratives participates in and showcases the broader globalising impulses of Tamil cinema in the twenty-first century. This paper focusses on two actors – Jyothika and Nayanthara – who have been instrumental in bringing to the fore a new figure in Tamil cinema, i.e. the ‘lady (super)star’. This paper theorises their rise to stardom as a set of complex negotiations between their personal and professional lives while navigating and resetting the boundaries of the ‘good Tamil woman’.
The purpose of this study was to adapt a Japanese version of the Big Five Inventory-2 (BFI-2-J) to examine its factor structure, reliability, validity, and measurement invariance. The BFI-2-J assesses five domains and 15 facets of the Big Five personality traits. We analyzed two datasets: 487 Japanese undergraduates and 500 Japanese adults. The results of the principal component analysis and confirmatory factor analysis revealed that the domain-facet structure of the BFI-2-J was similar to that of other language versions. The reliability of the BFI-2-J is sufficient. The correlation coefficients between the BFI-2-J and the other Big Five and self-esteem measures supported convergent and discriminant validity. Moreover, we confirmed measurement invariance across age and sex groups in domain-level and facet-level models. The results suggest that the BFI-2-J is a good instrument for measuring the Big Five personality traits and their facets in Japan. The BFI-2-J is expected to be useful in Japanese personality research and international comparative research.
An emerging area of research concerns the phenomenon of young people factoring climate change into their reproductive plans and choices, but existing scholarship and popular discourse have focused exclusively on Western and developed countries. This paper examines whether young people in China are also connecting their reproductive plans and choices to climate change, and why. Based on the quantitative and qualitative results from an exploratory survey of 173 young, educated, climate-alarmed or climate-concerned Chinese, we found that reproductive climate concerns are reported by many young Chinese. Respondents expressed deep and multi-layered concerns about the wellbeing of their (potential) children in a climate-changed future, though they did not rank climate change highly among other factors that might influence their reproductive choices. Climate-alarmed Chinese reported lower levels of reproductive climate concerns and more positive visions of the future than a similar group of US-Americans. We attribute these findings to China’s history of family planning, state-constructed climate discourse, stage of development, and hierarchical cultural worldview. As the first study on reproductive climate concerns in Asia, this research addresses a major gap in our knowledge, with implications for the sociology of climate change, the sociology of reproduction, environmental psychology, Asian studies, and demography.
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Robert A Gastaldo
  • Geology Department
Jennifer H Coane
  • Psychology Department
Denise A. Bruesewitz
  • Environmental Studies
Loren Mcclenachan
  • Environmental Studies
Catherine R Bevier
  • Biology Department
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