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Articles 145651 - 145680 of 302512

Full-Text Articles in Physical Sciences and Mathematics

Primary Spaces, Mackey’S Obstruction, And The Generalized Barycentric Decomposition, Patrick Iglesias-Zemmour, François Ziegler Jan 2015

Primary Spaces, Mackey’S Obstruction, And The Generalized Barycentric Decomposition, Patrick Iglesias-Zemmour, François Ziegler

François Ziegler

We call a hamiltonian N-space primary if its moment map is onto a single coadjoint orbit. The question has long been open whether such spaces always split as (homogeneous) × (trivial), as an analogy with representation theory might suggest. For instance, Souriau’s barycentric decomposition theorem asserts just this when N is a Heisenberg group. For general N, we give explicit examples which do not split, and show instead that primary spaces are always flat bundles over the coadjoint orbit. This provides the missing piece for a full “Mackey theory” of hamiltonian G-spaces, where G is an overgroup in which N …

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Variable Selection With False Discovery Control, Kevin He, Yanming Li, Ji Zhu, Hongliang Liu, Jeffrey E. Lee, Christopher I. Amos, Terry Hyslop, Jiashun Jin, Qinyi Wei, Yi Li Jan 2015

Variable Selection With False Discovery Control, Kevin He, Yanming Li, Ji Zhu, Hongliang Liu, Jeffrey E. Lee, Christopher I. Amos, Terry Hyslop, Jiashun Jin, Qinyi Wei, Yi Li

The University of Michigan Department of Biostatistics Working Paper Series

Technological advances that allow routine identification of high-dimensional risk factors have led to high demand for statistical techniques that enable full utilization of these rich sources of information for genome-wide association studies (GWAS). Variable selection for censored outcome data as well as control of false discoveries (i.e. inclusion of irrelevant variables) in the presence of high-dimensional predictors present serious challenges. In the context of survival analysis with high-dimensional covariates, this paper develops a computationally feasible method for building general risk prediction models, while controlling false discoveries. We have proposed a high-dimensional variable selection method by incorporating stability selection to control …

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Tests For Gene-Environment Interactions And Joint Effects With Exposure Misclassification, Philip S. Boonstra, Bhramar Mukherjee, Stephen B. Gruber, Jaeil Ahn, Stephanie L. Schmit, Nilanjan Chatterjee Jan 2015

Tests For Gene-Environment Interactions And Joint Effects With Exposure Misclassification, Philip S. Boonstra, Bhramar Mukherjee, Stephen B. Gruber, Jaeil Ahn, Stephanie L. Schmit, Nilanjan Chatterjee

The University of Michigan Department of Biostatistics Working Paper Series

The number of methods for genome-wide testing of gene-environment interactions (GEI) continues to increase with the hope of discovering new genetic risk factors and obtaining insight into the disease-gene-environment relationship. The relative performance of these methods based on family-wise type 1 error rate and power depends on underlying disease-gene-environment associations, estimates of which may be biased in the presence of exposure misclassification. This simulation study expands on a previously published simulation study of methods for detecting GEI by evaluating the impact of exposure misclassification. We consider seven single step and modular screening methods for identifying GEI at a genome-wide level …

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The Red Radio Ring: A Gravitationally Lensed Hyperluminous Infrared Radio Galaxy At Z=2.553 Discovered Through Citizen Science, J. E. Geach, A. More, A. Verma, P.J. Marshall, N. Jackson, P. E. Belles, R. Beswick, E. Baeten, M. Chavez, C. Cornen, B. E. Cox, T. Erben, N. J. Erickson, S. Garrington, P. A. Harrison, K. Harrington, D. H. Hughes, R. J. Ivison, C. Jordan, Y. T. Lin, A. Leauthaud, C. Lintott, S. Lynn, A. Kapadia, J. P. Kneib, C. Macmillan, M. Makler, G. Miller, A. Montana, R. Mujica, T. Muxlow, Gopal Narayanan, D. O Briain, T. O'Brien, M. Oguri, E. Paget, M. Parrish, N.P. Ross, E. Rozo, E. Rusu, E. S. Rykoff, D. Sanchez-Arguelles, R. Simpson, C. Snyder, F. P. Schloerb, M. Tecza, L. Van Waerbeke, J. Wilcox, M. Viero, G. W. Wilson, M. S. Yun, M. Zeballos Jan 2015

The Red Radio Ring: A Gravitationally Lensed Hyperluminous Infrared Radio Galaxy At Z=2.553 Discovered Through Citizen Science, J. E. Geach, A. More, A. Verma, P.J. Marshall, N. Jackson, P. E. Belles, R. Beswick, E. Baeten, M. Chavez, C. Cornen, B. E. Cox, T. Erben, N. J. Erickson, S. Garrington, P. A. Harrison, K. Harrington, D. H. Hughes, R. J. Ivison, C. Jordan, Y. T. Lin, A. Leauthaud, C. Lintott, S. Lynn, A. Kapadia, J. P. Kneib, C. Macmillan, M. Makler, G. Miller, A. Montana, R. Mujica, T. Muxlow, Gopal Narayanan, D. O Briain, T. O'Brien, M. Oguri, E. Paget, M. Parrish, N.P. Ross, E. Rozo, E. Rusu, E. S. Rykoff, D. Sanchez-Arguelles, R. Simpson, C. Snyder, F. P. Schloerb, M. Tecza, L. Van Waerbeke, J. Wilcox, M. Viero, G. W. Wilson, M. S. Yun, M. Zeballos

Gopal Narayanan

We report the discovery of a gravitationally lensed hyperluminous infrared galaxy (L_IR~10^13 L_sun) with strong radio emission (L_1.4GHz~10^25 W/Hz) at z=2.553. The source was identified in the citizen science project SpaceWarps through the visual inspection of tens of thousands of iJKs colour composite images of Luminous Red Galaxies (LRGs), groups and clusters of galaxies and quasars. Appearing as a partial Einstein ring (r_e~3") around an LRG at z=0.2, the galaxy is extremely bright in the sub-millimetre for a cosmological source, with the thermal dust emission approaching 1 Jy at peak. The redshift of the lensed galaxy is determined through the …

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The Herschel View Of The Dominant Mode Of Galaxy Growth From Z=4 To The Present Day, C. Schreiber, M. Pannella, D. Elbaz, M. Bethermin, H. Inami, M. Dickinson, B. Magnelli, T. Wang, H. Aussel, E. Daddi, S Juneau, X. Shu, M. T. Sargent, V. Buat, S.M. Faber, H.C. Ferguson, Mauro Giavalisco, A.M. Koekemoer, G. Magdis, G.E. Morrison, C. Papovich, P. Santini, D. Scott Jan 2015

The Herschel View Of The Dominant Mode Of Galaxy Growth From Z=4 To The Present Day, C. Schreiber, M. Pannella, D. Elbaz, M. Bethermin, H. Inami, M. Dickinson, B. Magnelli, T. Wang, H. Aussel, E. Daddi, S Juneau, X. Shu, M. T. Sargent, V. Buat, S.M. Faber, H.C. Ferguson, Mauro Giavalisco, A.M. Koekemoer, G. Magdis, G.E. Morrison, C. Papovich, P. Santini, D. Scott

Mauro Giavalisco

No abstract provided.

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Torque-Limited Growth Of Massive Black Holes In Galaxies Across Cosmic Tim, Daniel Angles-Alcazar, Feryal Ozel, Romeel Dave, Neal S. Katz, Juna Kollmeier, Benjamin D. Oppenheimer Jan 2015

Torque-Limited Growth Of Massive Black Holes In Galaxies Across Cosmic Tim, Daniel Angles-Alcazar, Feryal Ozel, Romeel Dave, Neal S. Katz, Juna Kollmeier, Benjamin D. Oppenheimer

Neal S. Katz

We combine cosmological hydrodynamic simulations with analytic models to evaluate the role of galaxy-scale gravitational torques on the evolution of massive black holes at the centers of star-forming galaxies. We confirm and extend our earlier results to show that torque-limited growth yields black holes and host galaxies evolving on average along the M BH-M bulge relation from early times down to z = 0 and that convergence onto the scaling relation occurs independent of the initial conditions and with no need for mass averaging through mergers or additional self-regulation processes. Smooth accretion dominates the long-term evolution, with black hole mergers …

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Csi 2264: Characterizing Young Stars In Ngc 2264 With Short-Duration, Periodic Flux Dips In Their Light Curves, John Stauffer, Ann Marie Cody, Pauline Mcginnis, Luisa Rebull, Lynne A. Hillenbrand, Neal. J. Turner, John Carpenter, Peter Plavchan, Sean Carey, Susan Terebey, Maria Morales-Calderon, Silvia H.P. Alencar, Jerome Bouvier, Laura Venuti, Lee Hartmann, Nuria Calvet, Giushi Micela, Ettore Flaccomio, Inseok Song, R. A. Gutermuth, David Barrado, Frederick J. Vrba, Kevin Covey, Debbie Padgett, William Herbst, Edward Gillen, Wladimir Lyra, Marcelo Medeiros Guimaraes, Herve Bouy, Fabio Favata Jan 2015

Csi 2264: Characterizing Young Stars In Ngc 2264 With Short-Duration, Periodic Flux Dips In Their Light Curves, John Stauffer, Ann Marie Cody, Pauline Mcginnis, Luisa Rebull, Lynne A. Hillenbrand, Neal. J. Turner, John Carpenter, Peter Plavchan, Sean Carey, Susan Terebey, Maria Morales-Calderon, Silvia H.P. Alencar, Jerome Bouvier, Laura Venuti, Lee Hartmann, Nuria Calvet, Giushi Micela, Ettore Flaccomio, Inseok Song, R. A. Gutermuth, David Barrado, Frederick J. Vrba, Kevin Covey, Debbie Padgett, William Herbst, Edward Gillen, Wladimir Lyra, Marcelo Medeiros Guimaraes, Herve Bouy, Fabio Favata

Robert A. Gutermuth

We identify nine young stellar objects (YSOs) in the NGC 2264 star-forming region with optical CoRoT light curves exhibiting short-duration, shallow periodic flux dips. All of these stars have infrared excesses that are consistent with their having inner disk walls near the Keplerian co-rotation radius. The repeating photometric dips have FWHMs generally less than 1 day, depths almost always less than 15%, and periods (3 < P < 11 days) consistent with dust near the Keplerian co-rotation period. The flux dips vary considerably in their depth from epoch to epoch, but usually persist for several weeks and, in two cases, were present in data collected in successive years. For several of these stars, we also measure the photospheric rotation period and find that the rotation and dip periods are the same, as predicted by standard "disk-locking" models. We attribute these flux dips to clumps of material in or near the inner disk wall, passing through our line of sight to the stellar photosphere. In some cases, these dips are also present in simultaneous Spitzer IRAC light curves at 3.6 and 4.5 microns. We characterize the properties of these dips, and compare the stars with light curves exhibiting this behavior to other classes of YSOs in NGC 2264. A number of physical mechanisms could locally increase the dust scale height near the inner disk wall, and we discuss several of those mechanisms; the most plausible mechanisms are either a disk warp due to interaction with the stellar magnetic field or dust entrained in funnel-flow accretion columns arising near the inner disk wall.

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Elevation-Dependent Warming In Mountain Regions Of The World, Mountain Research Institute, Nicolas Pepin, Raymond S. Bradley Jan 2015

Elevation-Dependent Warming In Mountain Regions Of The World, Mountain Research Institute, Nicolas Pepin, Raymond S. Bradley

Raymond S Bradley

"There is growing evidence that the rate of warming is amplified with elevation, such that high-mountain environments experience more rapid changes in temperature than environments at lower elevations. Elevation-dependent warming (EDW) can accelerate the rate of change in mountain ecosystems, cryospheric systems, hydrological regimes and biodiversity. Here we review important mechanisms that contribute towards EDW: snow albedo and surface-based feedbacks; water vapour changes and latent heat release; surface water vapour and radiative flux changes; surface heat loss and temperature change; and aerosols. All lead to enhanced warming with elevation (or at a critical elevation), and it is believed that combinations …

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Winter Climate Extremes Over The Northeastern United States And Southeastern Canada And Teleconnections With Large-Scale Modes Of Climate Variability, Liang Ning, Raymond S. Bradley Jan 2015

Winter Climate Extremes Over The Northeastern United States And Southeastern Canada And Teleconnections With Large-Scale Modes Of Climate Variability, Liang Ning, Raymond S. Bradley

Raymond S Bradley

The relationship between winter climate extremes across the northeastern United States and adjacent parts of Canada and some important modes of climate variability are examined to determine how these circulation patterns are related to extreme events. Linear correlations between 15 extreme climate indices related to winter daily precipitation, maximum and minimum temperature, and three dominant large-scale patterns of climate variability [the North Atlantic Oscillation (NAO), Pacific–North American (PNA) pattern, and El Niño–Southern Oscillation (ENSO)] were analyzed for the period 1950–99. The mechanisms behind these teleconnections are analyzed by applying composite analysis to the geopotential height, sea level pressure (SLP), moisture …

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Transitions From Order To Disorder In Multi-Dark And Multi-Dark-Bright Soliton Atomic Clouds, Wenlong Wang, Panos Kevrekidis Jan 2015

Transitions From Order To Disorder In Multi-Dark And Multi-Dark-Bright Soliton Atomic Clouds, Wenlong Wang, Panos Kevrekidis

Panos Kevrekidis

We have performed a systematic study quantifying the variation of solitary wave behavior from that of an ordered cloud resembling a “crystalline” configuration to that of a disordered state that can be characterized as a soliton “gas.” As our illustrative examples, we use both one-component, as well as two-component, one-dimensional atomic gases very close to zero temperature, where in the presence of repulsive interatomic interactions and of a parabolic trap, a cloud of dark (dark-bright) solitons can form in the one- (two-) component system. We corroborate our findings through three distinct types of approaches, namely a Gross-Pitaevskii type of partial …

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Fluctuation-Induced First Order Phase Transitions In Type-1.5 Superconductors In Zero External Field, Hannes Meier, Egor Babaev, Mats Wallin Jan 2015

Fluctuation-Induced First Order Phase Transitions In Type-1.5 Superconductors In Zero External Field, Hannes Meier, Egor Babaev, Mats Wallin

Egor Babaev

No abstract provided.

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Pathwise Sensitivity Analysis In Transient Regimes, Georgios Arampatzis, Markos Katsoulakis, Yannis Pantazis Jan 2015

Pathwise Sensitivity Analysis In Transient Regimes, Georgios Arampatzis, Markos Katsoulakis, Yannis Pantazis

Markos Katsoulakis

The instantaneous relative entropy (IRE) and the corresponding instantaneous Fisher information matrix (IFIM) for transient stochastic processes are presented in this paper. These novel tools for sensitivity analysis of stochastic models serve as an extension of the well known relative entropy rate (RER) and the corresponding Fisher information matrix (FIM) that apply to stationary processes. Three cases are studied here, discrete-time Markov chains, continuous-time Markov chains and stochastic differential equations. A biological reaction network is presented as a demonstration numerical example.

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Birational Geometry Of Cluster Algebras, Mark Gross, Paul Hacking, Sean Keel Jan 2015

Birational Geometry Of Cluster Algebras, Mark Gross, Paul Hacking, Sean Keel

Paul Hacking

We give a geometric interpretation of cluster varieties in terms of blowups of toric varieties. This enables us to provide, among other results, an elementary geometric proof of the Laurent phenomenon for cluster algebras (of geometric type), extend Speyer's example [Spe13] of upper cluster algebras which are not finitely generated, and show that the Fock-Goncharov dual basis conjecture is usually false.

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Generating Functions, Polynomials And Vortices With Alternating Signs In Bose-Einstein Condensates, Anna M. Barry, Farshid Hajir, P. G. Kevrekidis Jan 2015

Generating Functions, Polynomials And Vortices With Alternating Signs In Bose-Einstein Condensates, Anna M. Barry, Farshid Hajir, P. G. Kevrekidis

Farshid Hajir

In this work, we construct suitable generating functions for vortices of alternating signs in the realm of quasi-two-dimensional Bose–Einstein condensates in the large density (so-called Thomas–Fermi) limit, where the vortices can be treated as effective particles. In addition to the vortex–vortex interaction included in earlier fluid dynamics constructions of such functions, the vortices here precess around the center of the trap. This results in the generating functions of the vortices of positive charge and of negative charge satisfying a modified, so-called, Tkachenko differential equation. From that equation, we reconstruct collinear few-vortex equilibria obtained in earlier work, as well as extend …

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Dynamics Of Vortex Dipoles In Anisotropic Bose-Einstein Condensates, Roy H. Goodman, Panos Kevrekidis, R. Carretero-Gonzalez Jan 2015

Dynamics Of Vortex Dipoles In Anisotropic Bose-Einstein Condensates, Roy H. Goodman, Panos Kevrekidis, R. Carretero-Gonzalez

Panos Kevrekidis

We study the motion of a vortex dipole in a Bose--Einstein condensate confined to an anisotropic trap. We focus on a system of ODEs describing the vortices' motion, which is in turn a reduced model of the Gross--Pitaevskii equation describing the condensate's motion. Using a sequence of canonical changes of variables, we reduce the dimension and simplify the equations of motion. We uncover two interesting regimes. Near a family of periodic orbits known as guiding centers, we find that the dynamics is essentially that of a pendulum coupled to a linear oscillator, leading to stochastic reversals in the overall direction …

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Vortex Chains Due To Nonpairwise Interactions And Field-Induced Phase Transitions Between States With Different Broken Symmetry In Superconductors With Competing Order Parameters, Julien Garaud, Egor Babaev Jan 2015

Vortex Chains Due To Nonpairwise Interactions And Field-Induced Phase Transitions Between States With Different Broken Symmetry In Superconductors With Competing Order Parameters, Julien Garaud, Egor Babaev

Egor Babaev

We study superconductors with two order components and phase separation driven by intercomponent density-density interaction, focusing on the phase where only one condensate has nonzero ground-state density and a competing order parameter exists only in vortex cores. We demonstrate there that multibody intervortex interactions can be strongly nonpairwise, leading to some unusual vortex patterns in an external field, such as vortex pairs and vortex chains. We demonstrate that in an external magnetic field such a system undergoes a field-driven phase transition from (broken) U(1) to (broken) U(1)×U(1) symmetries when a subdominant order parameter in the vortex cores acquires global coherence. …

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Canonical Bases For Cluster Algebras, Mark Gross, Paul Hacking, Sean Keel, Maxim Kontesevich Jan 2015

Canonical Bases For Cluster Algebras, Mark Gross, Paul Hacking, Sean Keel, Maxim Kontesevich

Paul Hacking

In GHK11, Conjecture 0.6, the first three authors conjectured the ring of regular functions on a natural class of affine log Calabi-Yau varieties (those with maximal boundary) has a canonical vector space basis parameterized by the integral tropical points of the mirror. Further, the structure constants for the multiplication rule in this basis should be given by counting broken lines (certain combinatorial objects, morally the tropicalisations of holomorphic discs). Here we prove the conjecture in the case of cluster varieties, where the statement is a more precise form of the Fock-Goncharov dual basis conjecture, FG06, Conjecture 4.3. In particular, under …

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Spontaneous Breakdown Of Time-Reversal Symmetry Induced By Thermal Fluctuations, Johan Carlström, Egor Babaev Jan 2015

Spontaneous Breakdown Of Time-Reversal Symmetry Induced By Thermal Fluctuations, Johan Carlström, Egor Babaev

Egor Babaev

In systems with broken U(1) symmetry, such as superfluids, superconductors or magnets, the symmetry restoration is driven by proliferation of topological defects in the form of vortex loops. Here we discuss that in certain systems the proliferation of topological defects can, by contrast, lead to the breakdown of an additional symmetry. As a particular example we demonstrate that this effect should take place in s + is superconductors, which are widely discussed in connection with the Iron-based materials. In these systems a vortex excitation can create a “bubble" of fluctuating Z2 order parameter. Thermal excitation of vortices then leads to …

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Scattering Of Matter-Waves In Spatially Inhomogeneous Environments, F. Tsitoura, P. Kruger, Panos Kevrekidis, D. J. Frantzeskakis Jan 2015

Scattering Of Matter-Waves In Spatially Inhomogeneous Environments, F. Tsitoura, P. Kruger, Panos Kevrekidis, D. J. Frantzeskakis

Panos Kevrekidis

We study scattering of quasi-one-dimensional matter waves at an interface of two spatial domains, one with repulsive and one with attractive interatomic interactions. It is shown that the incidence of a Gaussian wave packet from the repulsive to the attractive region gives rise to generation of a soliton train. More specifically, the number of emergent solitons can be controlled, e.g., by the variation of the amplitude or the width of the incoming wave packet. Furthermore, we study the reflectivity of a soliton incident from the attractive region to the repulsive one. We find the reflection coefficient numerically and employ analytical …

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Moduli Of Surfaces With An Anti-Canonical Cycle, Mark Gross, Paul Hacking, Sean Keel Jan 2015

Moduli Of Surfaces With An Anti-Canonical Cycle, Mark Gross, Paul Hacking, Sean Keel

Paul Hacking

We prove a global torelli theorem for pairs (Y,D) where Y is a smooth projective rational surface and D ∈ |−Ky | is a cycle of rational curves, as conjectured by Friedman in 1984. In addition, we construct natural universal families for such pairs.

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Solitons And Vortices In Two-Dimensional Discrete Nonlinear Schrodinger Systems With Spatially Modulated Nonlinearity, Panos Kevrekidis Jan 2015

Solitons And Vortices In Two-Dimensional Discrete Nonlinear Schrodinger Systems With Spatially Modulated Nonlinearity, Panos Kevrekidis

Panos Kevrekidis

We consider a two-dimensional (2D) generalization of a recently proposed model [Gligorić et al., Phys. Rev. E 88, 032905 (2013)], which gives rise to bright discrete solitons supported by the defocusing nonlinearity whose local strength grows from the center to the periphery. We explore the 2D model starting from the anticontinuum (AC) limit of vanishing coupling. In this limit, we can construct a wide variety of solutions including not only single-site excitations, but also dipole and quadrupole ones. Additionally, two separate families of solutions are explored: the usual “extended” unstaggered bright solitons, in which all sites are excited in the …

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Validation Of Recent Shear Wave Velocity Models In The United States With Full-Wave Simulation, Haiying Gao, Yang Shen Jan 2015

Validation Of Recent Shear Wave Velocity Models In The United States With Full-Wave Simulation, Haiying Gao, Yang Shen

Haiying Gao

Interpretations of dynamic processes and the thermal and chemical structure of the Earth depend on the accuracy of Earth models. With the growing number of velocity models constructed with different tomographic methods and seismic data sets, there is an increasing need for a systematic way to validate model accuracy and resolution. This study selects five shear wave velocity models in the U.S. and simulates full wave propagation within the 3-D structures. Surface-wave signals extracted from ambient seismic noise and regional earthquakes are compared with synthetic waveforms at multiple-frequency bands. Phase delays and cross-correlation coefficients between observed and synthetic waveforms allow …

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Responses Of Global Terrestrial Evapotranspiration To Climate Change And Increasing Atmospheric Co2 In The 21st Century, Shufen Pan, Hanqin Tian, Shree R. S. Dangal, Qichun Yang, Jia Yang, Chaoqun (Crystal) Lu, Bo Tao, Wei Ren, Zhiyun Ouyang Jan 2015

Responses Of Global Terrestrial Evapotranspiration To Climate Change And Increasing Atmospheric Co2 In The 21st Century, Shufen Pan, Hanqin Tian, Shree R. S. Dangal, Qichun Yang, Jia Yang, Chaoqun (Crystal) Lu, Bo Tao, Wei Ren, Zhiyun Ouyang

Chaoqun (Crystal) Lu

Quantifying the spatial and temporal patterns of the water lost to the atmosphere through land surface evapotranspiration (ET) is essential for understanding the global hydrological cycle, but remains much uncertain. In this study, we use the Dynamic Land Ecosystem Model to estimate the global terrestrial ET during 2000–2009 and project its changes in response to climate change and increasing atmospheric CO2 under two IPCC SRES scenarios (A2 and B1) during 2010–2099. Modeled results show a mean annual global terrestrial ET of about 549 (545–552) mm yr−1 during 2000–2009. Relative to the 2000s, global terrestrial ET for the 2090s would increase …

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Moffatt Eddies In The Single Screw Extruder: Numerical And Analytical Study, Petru S. Fodor, Miron Kaufman Jan 2015

Moffatt Eddies In The Single Screw Extruder: Numerical And Analytical Study, Petru S. Fodor, Miron Kaufman

Miron Kaufman

A detailed analysis of the fluid flow in the single screw extruder is performed by combining numerical and analytical methods. While finite element analysis numerical models are used to extract the transversal velocity field, an analytical model in the limit of zero Reynolds numbers is used to determine the longitudinal component of the fluid velocities. The high resolution 3D model developed for the fluid flow in single screw extruders with aspect ratios (i.e. depth/width) ranging from 1 to 0.1, allows the identification of the position and extent of Moffatt eddies that impede the fluid mixing through the entire extruder’s volume. …

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Mercury Speciation, Retention, And Abundance Of Genes Involved With Mercury Methylation In Fertilized Salt Marsh Sediments, Caroline Collins Jan 2015

Mercury Speciation, Retention, And Abundance Of Genes Involved With Mercury Methylation In Fertilized Salt Marsh Sediments, Caroline Collins

Biology Honors Papers

Mercury (Hg) is a global pollutant which exists in both aquatic and terrestrial systems in three main forms including elemental Hg, ionic mercury, and methyl mercury, (MeHg), and Hg cycling plays an important role in ecosystems. Great Sippewisset Marsh, (GSM) in Falmouth MA has been chronically treated with fertilizer that contains heavy metals such as Hg in varying concentrations since the early 1970s and provides for an excellent location to study Hg contamination. The overall goal of this study is to analyze the key geochemical and microbial conditions that lead to MeHg production in the presence of the applied fertilizer. …

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Bulletin No. 40: Salt Marsh Plants Of Long Island Sound, R. Scott Warren, Juliana Barrett, Margaret Van Patten Jan 2015

Bulletin No. 40: Salt Marsh Plants Of Long Island Sound, R. Scott Warren, Juliana Barrett, Margaret Van Patten

Bulletins

No abstract provided.

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"What Is Love?" The Sounds Of Love From William S. Burroughs, Kathryn Cronin Jan 2015

"What Is Love?" The Sounds Of Love From William S. Burroughs, Kathryn Cronin

Occam's Razor

William Burroughs, his life and works, have a set beginning and end, but the biological and spiritual connections he draws between language, sound, and the human body appear to have undefined points of origin. Sound has always been. Language has always been. To exist outside of language and sound is to exist outside of time and space and thus outside the body. Burroughs’ theories on language, the word, and their connection to the body are woven through texts filled with structural and narrative convolutions. ­ Nova Trilogy, especially The Ticket that Exploded, as well as the early novel …

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Occam's Razor Vol. 5 - Full (2015) Jan 2015

Occam's Razor Vol. 5 - Full (2015)

Occam's Razor

No abstract provided.

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An Analysis Of Diatom Growth Rate And The Implications For The Biodiesel Industry, Sara Spitzer Jan 2015

An Analysis Of Diatom Growth Rate And The Implications For The Biodiesel Industry, Sara Spitzer

Occam's Razor

The need for an economically-feasible, carbon-neutral fuel source rises as rates of carbon emissions increase and climate change persists. Diatom biodiesel is currently being researched as a carbon-neutral alternative to petroleum. Biochemical engineering, a method utilized to increase lipid accumulation in microalgae for harvest, works by stressing algal cultures in order to bias their metabolism towards lipid (fat) production. Although Nitrogen (N) is the most common limiting-nutrient in research, Silicon (Si) is also vital to diatom cell growth and division, and therefore its limitation would also cause an accumulation of lipids in cells. In fact, Si-limitation has yielded higher lipid …

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Somewhat Stochastic Matrices, Branko Ćurgus, Robert I. Jewett Jan 2015

Somewhat Stochastic Matrices, Branko Ćurgus, Robert I. Jewett

Mathematics Faculty Publications

The standard theorem for stochastic matrices with positive entries is generalized to matrices with no sign restriction on the entries. The condition that column sums be equal to 1 is kept, but the positivity condition is replaced by a condition on the distances between columns.

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