Showing 5051 - 5100 of 5831 Items
Statement by Anonymous collected by Rachel George on October 14, 2014
Date: 2014-10-14
Creator: Anonymous
Access: Open access
Statement by Kirk Francis collected by Charlotte Bacon on November 4, 2014
Date: 2014-11-04
Creator: Kirk Francis
Access: Open access
Statement by Molly Newell and Mary Lou Barnes collected by Margo Milliken on November 22, 2013
Date: 2013-11-22
Access: Open access
Statement by Melody Paul collected by Rachel George on December 13, 2013
Date: 2013-12-13
Access: Open access
Statement by Sandra McDonald collected by Marcie Lister on August 6, 2014
Date: 2014-08-06
Access: Open access
Statement by Joshua Gagnon collected by Rachel George on May 1, 2014
Date: 2014-05-01
Access: Open access
Statement by Tyneshia Wright collected by Rachel George on March 27, 2014
Date: 2014-03-27
Access: Open access
Statement by Regina Petit collected by Charlotte Bacon on April 9, 2014
Date: 2014-04-09
Access: Open access
Statement by Gail D'Agostino collected by Meredith Eaton on July 10, 2014
Date: 2014-07-10
Access: Open access
Statement by Anonymous collected by Joan Uraneck on November 3, 2014
Date: 2014-11-03
Access: Open access
Investigating the Effects of Student Debt on Career Outcomes: An Empirical Approach
Date: 2019-05-01
Creator: Gideon Moore
Access: Open access
- High student debt has been hypothesized to affect career choice, causing students to desire stable, high paying jobs. To test this hypothesis, I rely on plausibly exogenous variation in debt due to a federal policy shift. In the summer of 2007, the Higher Education Reconciliation Act (or HERA) expanded the cap for federally subsidized student loans. I examine how variation in debt affects career choice and eventual salary of students using data from the National Longitudinal Survey of Youth 1979 Child and Young Adult Cohort of students who were of college age during the implementation of the policy. I find that student debt has no impact on salary two years after graduation; however, it does seem to shift students’ career choices, leading some to avoid careers in public service industries such as teaching and social work.
Exploring film language with a digital analysis tool: The case of kinolab
Date: 2021-01-01
Creator: Allison Cooper, Fernando Nascimento, David Francis
Access: Open access
- This article presents a case study of Kinolab, a digital platform for the analysis of narrative film language. It describes the need for a scholarly database of clips focusing on film language for cinema and media studies faculty and students, highlighting recent technological and legal advances that have created a favorable environment for this kind of digital humanities work. Discussion of the project is situated within the broader context of contemporary developments in moving image annotation and a discussion of the unique challenges posed by computationally-driven moving image analysis. The article also argues for a universally accepted data model for film language to facilitate the academic crowdsourcing of film clips and the sharing of research and resources across the Semantic Web.
Crazy American
Date: 2022-01-01
Creator: Emma Quan Dewey
Access: Open access
- Crazy American is an evening-length dance solo choreographed and performed by Bowdoin's first Dance honors student, Emma Quan Dewey. This dance is an embodied exploration of her mother's family migration history from South China to the Philippines to the US, and how it places her and her family within structures of US imperialism, racial hierarchies, and Chineseness itself. Based on ethnographic, historical, theoretical, and embodied research, Crazy American examines the intimate ways these structures play out at the level of the body, and seeks to imagine new possibilities for moving through systems and stories of power.
Modeling Oyster Growth Dynamics in FLUPSY Systems to Develop a Decision Support Tool for Seed Management
Date: 2023-01-01
Creator: Gretchen Clauss
Access: Open access
- As the Gulf of Maine warms and lobsters move north to colder waters, Maine’s working water front has begun to diversify. There is a thriving new ecosystem of aquaculturists looking to keep Maine’s waterfront traditions alive in a lasting, sustainable way. One of the most popular aquaculture industries is oyster farming. With an increasing number of oyster farms developing in Midcoast Maine each year, we seek to develop a decision support tool to aid farmers in seed management. Oyster farmers can choose weather or not to use an upweller on their farm, and our goal is to provide guidance on this choice, as well as on upweller management. We begin by culminating and synthesizing data from previous literature and oyster farmers. We then use this data to first build a basic analytical model of a cohort of oysters based on an exponential growth model. We expand this model to include biological differences among oysters as well as management practices. Finally, we walk through a case study, illustrating how our tool could be used to make seed management decisions on an individual farm scale.
Lake water chemistry and local adaptation shape NaCl toxicity in Daphnia ambigua
Date: 2024-01-01
Creator: Mary Alta Rogalski, Elizabeth S Baker, Clara M Benadon
Access: Open access
- Increasing application of road deicing agents (e.g., NaCl) has caused widespread salinization of freshwater environments. Chronic exposure to toxic NaCl levels can impact freshwater biota at genome to ecosystem scales, yet the degree of harm caused by road salt pollution is likely to vary among habitats and populations. The background ion chemistry of freshwater environments may strongly impact NaCl toxicity, with greater harm occurring in ion-poor, soft water conditions. In addition, populations exposed to salinization may evolve increased NaCl tolerance. Notably, if organisms are adapted to their natal lake water chemistry, toxicity responses may also vary among populations in a given test medium. We examined how this evolutionary and environmental context may interact in shaping NaCl toxicity with a pair of laboratory reciprocal transplant toxicity experiments, using natural populations of the water flea Daphnia ambigua from three lakes differing in ion availability. The lake water environment strongly influenced NaCl toxicity in both trials. NaCl greatly reduced reproduction and r in lake water from a low-ion/ calcium-poor environment compared with water from both a calcium-rich lake and an ion-rich coastal lake. Daphnia from this coastal lake were most robust to the effects of NaCl. A significant population x environment interaction shaped survival in both trials, suggesting that local adaptation to the test waters used contributed to toxicity responses. Our findings that the lake water environment, adaptation to that environment, and adaptation to a focal contaminant may shape toxicity demonstrate the importance of considering environmental and biological complexity in mitigating pollution impacts.
Henry Wadsworth Longfellow to William Wood, Brunswick, 1835 Feb 27 regarding his impending departure from Bowdoin [4p.]
Date: 1835-02-27
Creator: Henry Wadsworth Longfellow
Access: Open access
- Letter from Henry Wadsworth Longfellow to William Wood regarding his impending departure from Bowdoin.
Map of Brunswick and Topsham, Maine
Date: 1877-01-01
Access: Open access
- Lithograph panoramic view looking north.
Exploring Solution-Based Co-Crystal Growth of Curcumin as an Approach for Alzheimer’s Therapeutics Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Nadia E. Puente
Access: Access restricted to the Bowdoin Community
Dynamic Multi-Objective Optimization With Applications to AI for Social Good Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Sajel Surati
Access: Access restricted to the Bowdoin Community
Settling down to a long winter's nap: Seasonality and temperature on evergreen entrance into winter dormancy Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Roger M. Wilder
Access: Access restricted to the Bowdoin Community
Using Fluorogenic Monosaccharides to Detect and Identify Glycan-Degrading Enzymes Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Esteban Tarazona Guzman
Access: Access restricted to the Bowdoin Community
The Collision of Oil and Anticolonial Nationalism in the Persian Gulf
Date: 2025-01-01
Creator: Vaughn Vial
Access: Open access
- In the 1950s and 1960s, Arab nationalism swept across the Arabian Peninsula from Egypt and the Levant, carried by migrants, refugees, and in magazines and newspapers that circulated across national borders. In the Gulf countries this wave of Arab nationalism collided with a flow more material in nature: the movement of enormous amounts of carbon energy in the form of oil. In Arab nationalism, oil workers at Aramco in Saudi Arabia and Bapco in Bahrain found not only a direction for political change but a means of overcoming religious and national divides with their fellow workers. Strikes and labor actions soon ensued at a scale that was unprecedented in these countries. This project explores how the confluence of oil flows and anticolonial nationalism both imbued this moment with the potential to effect egalitarian political change and, simultaneously, limited that potential.
The Sublethal Impacts of Epizootic Shell Disease, Molting and Damage on Energy Storage and Immune Function in the American Lobster (Homarus americanus) Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Annika Ruth Bell
Access: Access restricted to the Bowdoin Community
Latent Landscapes: Deep Learning Techniques for Measuring Poverty and Vulnerability Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Brian Liu
Access: Access restricted to the Bowdoin Community
New Creatures in Old Gazes: Investigating Shifts Away from Anthropocentrism in Contemporary Animal Fiction
Date: 2025-01-01
Creator: Catherine Mose
Access: Open access
- This paper examines three works of animal-based fiction published within the last decade that all center on hypothetical forms of animals with a focus on decentering anthropocentric narratives of how much agency an animal is allowed to have in a human-centric narrative without engaging in anthropmorphism. By comparing the books with theory from the academic field of animal studies, older works of animal-based fiction, and historical debates surrounding the depiction of real-world animals in writing, I aim to interrogate the methods these authors use to decouple their animals' agency from anthropomorphism, and the ways in which this shift allows anthropocentrism to take new forms rather than be eradicated.
Exploring the functional role of theta oscillations in top-down control of episodic memory retrieval Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Emma F.B. Gibbens
Access: Access restricted to the Bowdoin Community
Suite For a Changing Climate
Date: 2025-01-01
Creator: Hayden Byrne
Access: Open access
- Suite for a Changing Climate is a set of compositions inspired by the changing rhythms of the New England seasons and the evolving ways in which we experience them in the shadow of climate change. Each piece captures a distinct facet of the seasonal year, whether rooted in sensory experience or in cultural memory, while reflecting on how these once-familiar patterns are being reshaped by environmental instability.
“I belong as much as I want to”: Changing Perceptions of Belonging through COVID and After among Elite Undergraduates Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Fiona Bor
Access: Access restricted to the Bowdoin Community
Exploring Eelgrass Restoration: Understanding Zostera marina seed development and germination in Casco Bay, ME Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Lucille Jean de Ferranti Dutton
Access: Access restricted to the Bowdoin Community
As Maine Goes
Date: 1966-01-01
Creator: John McKee, photographer, William O. Douglas, writer of introduction, Bowdoin College Museum of Art
Access: Open access
- Catalogue of an exhibition held at the Bowdoin College Museum of Art
The Progression of Women’s Studies in Higher Education, by Maya White
Date: 2023-12-01
Creator: Maya White
- This paper was submitted as part of EDUC 2285 Ivory Tower: Higher Education in American History, Fall 2023.
Atmospheric abundance and global emissions of perfluorocarbons CF4, C2F6 and C3F8 since 1800 inferred from ice core, firn, air archive and in situ measurements
Date: 2016-09-21
Creator: Cathy M. Trudinger, Paul J. Fraser, David M. Etheridge, William T. Sturges, Martin K. Vollmer, Matt Rigby, Patricia Martinerie, Jens Mühle, David R. Worton, Paul B. Krummel, L. Paul Steele, Benjamin R. Miller, Johannes Laube, Francis S. Mani, Peter J. Rayner, Christina M. Harth, Emmanuel Witrant, Thomas Blunier, Jakob Schwander, Simon O'Doherty, Mark Battle
Access: Open access
- Perfluorocarbons (PFCs) are very potent and long-lived greenhouse gases in the atmosphere, released predominantly during aluminium production and semiconductor manufacture. They have been targeted for emission controls under the United Nations Framework Convention on Climate Change. Here we present the first continuous records of the atmospheric abundance of CF4 (PFC-14), C2F6 (PFC-116) and C3F8 (PFC-218) from 1800 to 2014. The records are derived from high-precision measurements of PFCs in air extracted from polar firn or ice at six sites (DE08, DE08-2, DSSW20K, EDML, NEEM and South Pole) and air archive tanks and atmospheric air sampled from both hemispheres. We take account of the age characteristics of the firn and ice core air samples and demonstrate excellent consistency between the ice core, firn and atmospheric measurements. We present an inversion for global emissions from 1900 to 2014. We also formulate the inversion to directly infer emission factors for PFC emissions due to aluminium production prior to the 1980s. We show that 19th century atmospheric levels, before significant anthropogenic influence, were stable at 34.1 ± 0.3 ppt for CF4 and below detection limits of 0.002 and 0.01 ppt for C2F6 and C3F8, respectively. We find a significant peak in CF4 and C2F6 emissions around 1940, most likely due to the high demand for aluminium during World War II, for example for construction of aircraft, but these emissions were nevertheless much lower than in recent years. The PFC emission factors for aluminium production in the early 20th century were significantly higher than today but have decreased since then due to improvements and better control of the smelting process. Mitigation efforts have led to decreases in emissions from peaks in 1980 (CF4) or early-to-mid-2000s (C2F6 and C3F8) despite the continued increase in global aluminium production; however, these decreases in emissions appear to have recently halted. We see a temporary reduction of around 15 % in CF4 emissions in 2009, presumably associated with the impact of the global financial crisis on aluminium and semiconductor production.
Schwarzschild-de Sitter spacetimes, McVittie coordinates, and trumpet geometries
Date: 2017-12-15
Creator: Kenneth A. Dennison, Thomas W. Baumgarte
Access: Open access
- Trumpet geometries play an important role in numerical simulations of black hole spacetimes, which are usually performed under the assumption of asymptotic flatness. Our Universe is not asymptotically flat, however, which has motivated numerical studies of black holes in asymptotically de Sitter spacetimes. We derive analytical expressions for trumpet geometries in Schwarzschild-de Sitter spacetimes by first generalizing the static maximal trumpet slicing of the Schwarzschild spacetime to static constant mean curvature trumpet slicings of Schwarzschild-de Sitter spacetimes. We then switch to a comoving isotropic radial coordinate which results in a coordinate system analogous to McVittie coordinates. At large distances from the black hole the resulting metric asymptotes to a Friedmann-Lemaître-Robertson-Walker metric with an exponentially-expanding scale factor. While McVittie coordinates have another asymptotically de Sitter end as the radial coordinate goes to zero, so that they generalize the notion of a "wormhole" geometry, our new coordinates approach a horizon-penetrating trumpet geometry in the same limit. Our analytical expressions clarify the role of time-dependence, boundary conditions and coordinate conditions for trumpet slices in a cosmological context, and provide a useful test for black hole simulations in asymptotically de Sitter spacetimes.
General relativistic binary merger simulations and short gamma-ray bursts
Date: 2006-01-01
Creator: J.A. Faber, T.W. Baumgarte, S.L. Shapiro, K. Taniguchi
Access: Open access
Effect of differential rotation on the maximum mass of neutron stars: Realistic nuclear equations of state
Date: 2004-01-01
Creator: I.A. Morrison, T.W. Baumgarte, S.L. Shapiro
Access: Open access
Electronic branching ratio of the lepton
Date: 1992-01-01
Creator: R. Ammar, P. Baringer, D. Coppage, R. Davis, M., Kelly, N. Kwak, H. Lam, S. Ro, Y. Kubota, M. Lattery, J. K. Nelson, D. Perticone, R. Poling, S. Schrenk, R. Wang, M. S. Alam, I. J. Kim, B. Nemati, V. Romero, C. R. Sun, P. N. Wang, M. M. Zoeller, G. Crawford, R. Fulton, K. K. Gan, H. Kagan, R. Kass, J. Lee, R. Malchow, F. Morrow, M. K. Sung
Access: Open access
- Using data accumulated by the CLEO I detector operating at the Cornell Electron Storage Ring, we have measured the ratio R=( e» e ) 1 where " 1 is the decay rate to final states with one charged particle. We find R=0.2231 0.0044 0.0073 where the first error is statistical and the second is systematic. Together with the measured topological one-charged-particle branching fraction, this yields the branching fraction of the lepton to electrons, Be=0.192 0.004 0.006. © 1992 The American Physical Society.
Measurement of the c+ decay-asymmetry parameter
Date: 1990-01-01
Creator: P. Avery, D. Besson, L. Garren, J. Yelton, K., Kinoshita, F. M. Pipkin, M. Procario, Richard Wilson, J. Wolinski, D. Xiao, Y. Zhu, R. Ammar, P. Baringer, D. Coppage, R. Davis, P. Haas, M. Kelly, N. Kwak, Ha Lam, S. Ro, Y. Kubota, J. K. Nelson, D. Perticone, R. Poling, R. Fulton, T. Jensen, D. R. Johnson, H. Kagan, R. Kass, F. Morrow, J. Whitmore
Access: Open access
- We report a measurement of polarization in the two-body decay c+, in nonresonant e+e- interactions from data taken with the CLEO detector. Using these data we have determined the parity-violating asymmetry decay parameter c to be -1.0-0.0+0.4. We see no evidence for significant c+ polarization. © 1990 The American Physical Society.
A 60 yr record of atmospheric carbon monoxide reconstructed from Greenland firn air
Date: 2013-08-19
Creator: V. V. Petrenko, P. Martinerie, P. Novelli, D. M. Etheridge, I., Levin, Z. Wang, T. Blunier, J. Chappellaz, J. Kaiser, P. Lang, L. P. Steele, S. Hammer, J. Mak, R. L. Langenfelds, J. Schwander, J. P. Severinghaus, E. Witrant, G. Petron, M. O. Battle, G. Forster, W. T. Sturges, J. F. Lamarque, K. Steffen, J. W.C. White
Access: Open access
- We present the first reconstruction of the Northern Hemisphere (NH) high latitude atmospheric carbon monoxide (CO) mole fraction from Greenland firn air. Firn air samples were collected at three deep ice core sites in Greenland (NGRIP in 2001, Summit in 2006 and NEEM in 2008). CO records from the three sites agree well with each other as well as with recent atmospheric measurements, indicating that CO is well preserved in the firn at these sites. CO atmospheric history was reconstructed back to the year 1950 from the measurements using a combination of two forward models of gas transport in firn and an inverse model. The reconstructed history suggests that Arctic CO in 1950 was 140-150 nmol mol-1, which is higher than today's values. CO mole fractions rose by 10-15 nmol mol-1 from 1950 to the 1970s and peaked in the 1970s or early 1980s, followed by a ≈ 30 nmol mol-1 decline to today's levels. We compare the CO history with the atmospheric histories of methane, light hydrocarbons, molecular hydrogen, CO stable isotopes and hydroxyl radicals (OH), as well as with published CO emission inventories and results of a historical run from a chemistry-transport model. We find that the reconstructed Greenland CO history cannot be reconciled with available emission inventories unless unrealistically large changes in OH are assumed. We argue that the available CO emission inventories strongly underestimate historical NH emissions, and fail to capture the emission decline starting in the late 1970s, which was most likely due to reduced emissions from road transportation in North America and Europe. © Author(s) 2013.
Inelastic channels in WW scattering
Date: 1993-01-01
Creator: S. G. Naculich, C. P. Yuan
Access: Open access
- If the electroweak symmetry-breaking sector becomes strongly interacting at high energies, it can be probed through longitudinal W scattering. We present a model with many inelastic channels in the WLWL scattering process, corresponding to the production of heavy fermion pairs. These heavy fermions affect the elastic scattering of WL's by propagating in loops, greatly reducing the amplitudes in some charge channels. We conclude that the symmetry-breaking sector cannot be fully explored by using, for example, the WL±WL± mode alone, even when no resonance is present; all WLWL→WLWL scattering modes must be measured. © 1993 The American Physical Society.
Higgs-regularized three-loop four-gluon amplitude in N = 4 SYM: Exponentiation and Regge limits
Date: 2010-01-01
Creator: Johannes M. Henn, Stephen G. Naculich, Howard J. Schnitzer, Marcus Spradlin
Access: Open access
- We compute the three-loop contribution to the N = 4 supersymmetric Yang- Mills planar four-gluon amplitude using the recently-proposed Higgs IR regulator of Alday, Henn, Plefka, and Schuster. In particular, we test the proposed exponential ansatz for the four-gluon amplitude that is the analog of the BDS ansatz in dimensional regularization. By evaluating our results at a number of kinematic points, and also in several kinematic limits, we establish the validity of this ansatz at the three-loop level. We also examine the Regge limit of the planar four-gluon amplitude using several different IR regulators: dimensional regularization, Higgs regularization, and a cutoff regularization. In the latter two schemes, it is shown that the leading logarithmic (LL) behavior of the amplitudes, and therefore the lowest-order approximation to the gluon Regge trajectory, can be correctly obtained from the ladder approximation of the sum of diagrams. In dimensional regularization, on the other hand, there is no single dominant set of diagrams in the LL approximation. We also compute the NLL and NNLL behavior of the L-loop ladder diagram using Higgs regularization. © SISSA 2010.
Isospin mass splittings from precision measurements of D*-D mass differences
Date: 1992-01-01
Creator: D. Bortoletto, D. N. Brown, J. Dominick, R. L. Mcilwain, T., Miao, D. H. Miller, M. Modesitt, S. F. Schaffner, E. I. Shibata, I. P.J. Shipsey, M. Battle, J. Ernst, H. Kroha, S. Roberts, K. Sparks, E. H. Thorndike, C. H. Wang, S. Sanghera, T. Skwarnicki, R. Stroynowski, M. Artuso, M. Goldberg, N. Horwitz, R. Kennett, G. C. Moneti, F. Muheim, S. Playfer, Y. Rozen, P. Rubin, S. Stone, M. Thulasidas
Access: Open access
- Using the decay modes, D*+→D+π0 and D*0→D0π0, we have measured the D*+-D+ and D*0-D0 mass differences to be 140±0.08±0.06 and 142.12±0.05±0.05 MeV, respectively. Combining these measurements with the Particle Data Group average for the D*+-D0 mass difference, we obtain isospin mass splittings for D*+-Dusp*0 and D+-D0 of 3.32±0.08±0.05 and 4.80±0.10 ±0.06 MeV. We discuss the implications of these measurements for models of isospin mass differences and model-dependent estimates of fD. © 1992 The American Physical Society.
Inelastic channels in the electroweak symmetry-breaking sector
Date: 1992-10-29
Creator: S. G. Naculich, C. P. Yuan
Access: Open access
- It has been argued that if light Higgs bosons do not exist then the self-interactions of W's become strong in the TeV region and can be observed in longitudinal WW scattering. We present a model with many inelastic channels in the WW scattering process, corresponding to the creation of heavy fermion pairs. The presence of these heavy fermions affects the elastic scattering of W's by propagating in loops, greatly reducing the amplitudes in some charge channels. Consequently, the symmetry-breaking sector cannot be fully explored by using, for example, the W+W+ mode alone; all WW→WW scattering modes must be measured. © 1992.
Symmetric-group decomposition of SU(N) group-theory constraints on four-, five-, and six-point color-ordered amplitudes at all loop orders
Date: 2012-01-01
Creator: Alexander C. Edison, Stephen G. Naculich
Access: Open access
- Color-ordered amplitudes for the scattering of n particles in the adjoint representation of SU(N) gauge theory satisfy constraints that arise from group theory alone. These constraints break into subsets associated with irreducible representations of the symmetric group Sn, which allows them to be presented in a compact and natural way. Using an iterative approach, we derive the constraints for six-point amplitudes at all loop orders, extending earlier results for n = 4 and n = 5. We then decompose the four-, five-, and six-point group-theory constraints into their irreducible Sn subspaces. We comment briefly on higher-point two-loop amplitudes. © SISSA 2012.
Atmospheric measurements of the terrestrial O2 : CO2 exchange ratio of a midlatitude forest
Date: 2019-07-10
Creator: Mark O. Battle, J. William Munger, Margaret Conley, Eric Sofen, Rebecca, Perry, Ryan Hart, Zane Davis, Jacob Scheckman, Jayme Woogerd, Karina Graeter, Samuel Seekins, Sasha David, John Carpenter
Access: Open access
- Measurements of atmospheric O2 have been used to quantify large-scale fluxes of carbon between the oceans, atmosphere and land since 1992 (Keeling and Shertz, 1992). With time, datasets have grown and estimates of fluxes have become more precise, but a key uncertainty in these calculations is the exchange ratio of O2 and CO2 associated with the net land carbon sink (B). We present measurements of atmospheric O2 and CO2 collected over a 6-year period from a mixed deciduous forest in central Massachusetts, USA (42.537 N, 72.171 W). Using a differential fuel-cellbased instrument for O2 and a nondispersive infrared analyzer for CO2, we analyzed airstreams collected within and 5m above the forest canopy. Averaged over the entire period of record, we find these two species covary with a slope of -1:081±0:007 mol of O2 per mole of CO2 (the mean and standard error of 6 h periods). If we limit the data to values collected on summer days within the canopy, the slope is -1:03±0:01. These are the conditions in which biotic influences are most likely to dominate. This result is significantly different from the value of -1.1 widely used in O2-based calculations of the global carbon budget, suggesting the need for a deeper understanding of the exchange ratios of the various fluxes and pools comprising the net sink.
Large N universality of the two-dimensional Yang-Mills string
Date: 1995-07-17
Creator: Michael Crescimanno, Stephen G. Naculich, Howard J. Schnitzer
Access: Open access
- We exhibit the gauge-group independence ("universality") of all normalized non-intersecting Wilson loop expectation values in the large N limit of two-dimensional Yang-Mills theory. This universality is most easily understood via the string theory reformulation of these gauge theories. By constructing an isomorphism between the string maps contributing to normalized Wilson loop expectation values in the different theories, we prove the large N universality of these observables on any surface. The string calculation of the Wilson loop expectation value on the sphere also leads to an indication of the large N phase transition separating strong- and weak-coupling phases. © 1995.
Amplitudes for massive vector and scalar bosons in spontaneously-broken gauge theory from the CHY representation
Date: 2015-09-26
Creator: Stephen G. Naculich
Access: Open access
- Abstract: In the formulation of Cachazo, He, and Yuan, tree-level amplitudes for massless particles in gauge theory and gravity can be expressed as rational functions of the Lorentz invariants ka · kb, ϵa · kb, and ϵa · ϵb, valid in any number of spacetime dimensions. We use dimensional reduction of higher-dimensional amplitudes of particles with internal momentum κ to obtain amplitudes for massive particles in lower dimensions. In the case of gauge theory, we argue that these massive amplitudes belong to a theory in which the gauge symmetry is spontaneously broken by an adjoint Higgs field. Consequently, we show that tree-level n-point amplitudes containing massive vector and scalar bosons in this theory can be obtained by simply replacing ka · kb with ka · kb − κaκb in the corresponding massless amplitudes, where the masses of the particles are given by |κa|.
One-loop SYM-supergravity relation for five-point amplitudes
Date: 2011-11-21
Creator: Stephen G. Naculich, Howard J. Schnitzer
Access: Open access
- We derive a linear relation between the one-loop five-point amplitude of N = 8 supergravity and the one-loop five-point subleading-color amplitudes of N = 4 supersymmetric Yang-Mills theory. © 2011 SISSA.
Regge behavior of gluon scattering amplitudes in N = 4 SYM theory
Date: 2008-05-01
Creator: Stephen G. Naculich, Howard J. Schnitzer
Access: Open access
- It is shown that the four-gluon scattering amplitude for N = 4 supersymmetric Yang-Mills theory in the planar limit can be written, in both the weak- and strong-coupling limits, as a reggeized amplitude, with a parent trajectory and an infinite number of daughter trajectories. This result is not evident a priori, and relies crucially on the fact that the leading IR-divergence and the finite log2 (s / t)-dependent piece of the amplitude are characterized by the same function for all values of the coupling, as conjectured by Bern, Dixon, and Smirnov, and proved by Alday and Maldacena in the strong-coupling limit. We use the Alday-Maldacena result to determine the exact strong-coupling Regge trajectory. © 2007 Elsevier B.V. All rights reserved.
One-instanton test of a Seiberg-Witten curve from M-theory: The antisymmetric representation of SU(N)
Date: 1998-11-16
Creator: Stephen G. Naculich, Henric Rhedin, Howard J. Schnitzer
Access: Open access
- One-instanton predictions are obtained from the Seiberg-Witten curve derived from M-theory by Landsteiner and Lopez for the Coulomb branch of N = 2 supersymmetric SU(N) gauge theory with a matter hypermultiplet in the antisymmetric representation. Since this cubic curve describes a Riemann surface that is non-hyperelliptic, a systematic perturbation expansion about a hyperelliptic curve is developed, with a comparable expansion for the Seiberg-Witten differential. Calculation of the period integrals of the SW differential by the method of residues of D'Hoker, Krichever, and Phong enables us to compute the prepotential explicitly to one-instanton order. It is shown that the one-instanton predictions for SU(2), SU(3), and SU(4) agree with previously available results. For SU(N), N ≥ 5, our analysis provides explicit predictions of a curve derived from M-theory at the one-instanton level in field theory. © 1998 Elsevier Science B.V.