Showing 1501 - 1510 of 2040 Items
Statement by Anonymous collected by Rachel George on December 15, 2014
Date: 2014-12-15
Creator: Anonymous
Access: Open access
AF/AM/50 Oral History Project
- In the fall of 2019, students (Nate DeMoranville ‘20, Aisha Rickford ‘20, Marina Henke ‘19) conducted the AF/AM/50 Oral History Project to commemorate the 50th anniversary of the Africana Studies Program at the College. Over the course of the weekend, they interviewed more than 30 alumni, past professors, and staff. Interviewees varied across many spectrums: black and white, old and young. Some had not been back to Bowdoin for more than a decade. Others still lived in Brunswick. While in no way entirely encompassing the experience of black students at Bowdoin or the history of the Africana Studies Program, this project aimed to provide a window into the lives of a select few. These selections are not representative. No path through Bowdoin was identical. Hopes for the future of the College ranged widely. Themes and topics certainly emerged: of isolation, of prejudice, of pushback, but also of friendship and resilience.
Resistance to dislodgement: habitat and size-specific differences in morphology and tenacity in an intertidal snail
Date: 1993-01-01
Creator: G. C. Trussell
A. S. Johnson
S. G. Rudolph
E. S. Gilfillan
Access: Open access
- The authors quantified 1) shell size (defined as the maximum projected surface area, MPSA); 2) shell shape; 3) foot area; 4) maximum force to dislodge a snail in shear; and 5) tenacity (force per foot area required to dislodge) of the herbivorous Littorina obtusata. Wave-exposed snails were smaller (lower average MPSA), and were shorter and had larger foot area and greater dislodgement force than did protected snails of similar MPSA. The greater dislodgement force at the exposed site was due to larger foot area, not to greater tenacity. -from Authors
Two-loop graviton scattering relation and IR behavior in N = 8 supergravity
Date: 2008-12-11
Creator: Stephen G. Naculich
Horatiu Nastase
Howard J. Schnitzer
Access: Open access
- We derive an ABDK-like relation between the one- and two-loop four-graviton amplitudes in N = 8 supergravity. Specifically we show that the infrared-divergent part of the two-loop amplitude is one-half the square of the one-loop amplitude, suggesting an exponential structure for IR divergences. The difference between the two-loop amplitude and one-half the square of the full one-loop amplitude is therefore finite, and expressible in a relatively simple form. We give arguments for generalizations to higher loops and n-point functions, suggesting that the exponential of the full one-loop amplitude may be corrected, to low orders, by only simple finite terms. © 2008 Elsevier B.V. All rights reserved.
Level-rank duality of untwisted and twisted D-branes of the over(so, ̂) (N)K WZW model
Date: 2007-12-24
Creator: Stephen G. Naculich
Benjamin H. Ripman
Access: Open access
- We analyze the level-rank duality of untwisted and ε-twisted D-branes of the over(so, ̂) (N)K WZW model. Untwisted D-branes of over(so, ̂) (N)K are characterized by integrable tensor and spinor representations of over(so, ̂) (N)K. Level-rank duality maps untwisted over(so, ̂) (N)K D-branes corresponding to (equivalence classes of ) tensor representations onto those of over(so, ̂) (K)N. The ε-twisted D-branes of over(so, ̂) (2 n)2 k are characterized by (a subset of ) integrable tensor and spinor representations of over(so, ̂) (2 n - 1)2 k + 1. Level-rank duality maps spinor ε-twisted over(so, ̂) (2 n)2 k D-branes onto those of over(so, ̂) (2 k)2 n. For both untwisted and ε-twisted D-branes, we prove that the spectrum of an open string ending on these D-branes is isomorphic to the spectrum of an open string ending on the level-rank-dual D-branes. © 2007 Elsevier B.V. All rights reserved.
Ploidy variation in fungi: Polyploidy, aneuploidy, and genome evolution
Date: 2017-07-01
Creator: Robert T. Todd
Anja Forche
Anna Selmecki
Access: Open access
- The ability of an organism to replicate and segregate its genome with high fidelity is vital to its survival and for the production of future generations. Errors in either of these steps (replication or segregation) can lead to a change in ploidy or chromosome number. While these drastic genome changes can be detrimental to the organism, resulting in decreased fitness, they can also provide increased fitness during periods of stress. A change in ploidy or chromosome number can fundamentally change how a cell senses and responds to its environment. Here, we discuss current ideas in fungal biology that illuminate how eukaryotic genome size variation can impact the organism at a cellular and evolutionary level. One of the most fascinating observations from the past 2 decades of research is that some fungi have evolved the ability to tolerate large genome size changes and generate vast genomic heterogeneity without undergoing canonical meiosis.
Thompson's group F is 1-counter graph automatic
Date: 2016-05-01
Creator: Murray Elder
Jennifer Taback
Access: Open access
- It is not known whether Thompson's group F is automatic. With the recent extensions of the notion of an automatic group to graph automatic by Kharlampovich, Khoussainov and Miasnikov and then to C-graph automatic by the authors, a compelling question is whether F is graph automatic or C-graph automatic for an appropriate language class C. The extended definitions allow the use of a symbol alphabet for the normal form language, replacing the dependence on generating set. In this paper we construct a 1-counter graph automatic structure for F based on the standard infinite normal form for group elements.
Twisted D-branes of the over(su, ̂) (N)K WZW model and level-rank duality
Date: 2006-10-30
Creator: Stephen G. Naculich
Howard J. Schnitzer
Access: Open access
- We analyze the level-rank duality of ωc-twisted D-branes of over(su, ̂) (N)K (when N and K > 2). When N or K is even, the duality map involves Z2-cominimal equivalence classes of twisted D-branes. We prove the duality of the spectrum of an open string stretched between ωc-twisted D-branes, and ascertain the relation between the charges of level-rank-dual ωc-twisted D-branes. © 2006 Elsevier B.V. All rights reserved.
Erratum: The 'obligate diploid' Candida albicans forms mating-competent haploids (Nature (2013) 494 (55-59) DOI: 10.1038/nature11865)
Date: 2016-02-11
Creator: Meleah A. Hickman
Guisheng Zeng
Anja Forche
Matthew P. Hirakawa
Darren, Abbey
Benjamin D. Harrison
Yan Ming Wang
Ching Hua Su
Richard J. Bennett
Yue Wang
Judith Berman
Access: Open access
C-graph automatic groups
Date: 2014-09-01
Creator: Murray Elder
Jennifer Taback
Access: Open access
- We generalize the notion of a graph automatic group introduced by Kharlampovich, Khoussainov and Miasnikov by replacing the regular languages in their definition with more powerful language classes. For a fixed language class C, we call the resulting groups C-graph automatic. We prove that the class of C-graph automatic groups is closed under change of generating set, direct and free product for certain classes C. We show that for quasi-realtime counter-graph automatic groups where normal forms have length that is linear in the geodesic length, there is an algorithm to compute normal forms (and therefore solve the word problem) in polynomial time. The class of quasi-realtime counter-graph automatic groups includes all Baumslag-Solitar groups, and the free group of countably infinite rank. Context-sensitive-graph automatic groups are shown to be a very large class, which encompasses, for example, groups with unsolvable conjugacy problem, the Grigorchuk group, and Thompson's groups F, T and V. © 2014 Elsevier Inc.