Showing 4151 - 4200 of 5831 Items
Bowdoin College Catalogue (1908-1909)
Date: 1909-01-01
Access: Open access
- Bowdoin College Bulletin no. 20
A cell wall-associated, receptor-like protein kinase
Date: 1996-09-05
Creator: Zheng Hui He, Masaaki Fujiki, Bruce D. Kohorn
Access: Open access
- Physical connections between higher plant cell walls and the plasma membrane have been identified visually, but the molecules involved in the contact are unknown. We describe here an Arabidopsis thaliana protein kinase, designated Wak1 for wall-associated kinase, whose predicted extracytoplasmic domain contains several epidermal growth factor repeats and identity with a viral movement protein. Wak1 fractionates with insoluble material when plant tissue is ground in a variety of buffers and detergents, suggesting a tight association with the plant extracellular matrix. Immunocytochemistry confirms that Wak1 is associated with the cell wall. Enzymatic digestion of the cell wall allows the release of Wak1 from the insoluble cell wall fraction, and protease experiments indicate that Wak1 likely has a cytoplasmic kinase domain, and the EGF containing domain is extracellular. Wak1 is found in all vegetative tissues of Arabidopsis, and has relatives in other angiosperms, but not Chlamydomonas. We suggest that Wak1 is a good candidate for a physical continuum between the cell wall and the cytoplasm, and since the kinase is cytoplasmic, it also has the potential to mediate signals to the cytoplasm from the cell wall.
Functional and mutational analysis of the light-harvesting chlorophyll a/b protein of thylakoid membranes.
Date: 1986-01-01
Creator: B. D. Kohorn, E. Harel, P. R. Chitnis, J. P. Thornber, E. M., Tobin
Access: Open access
- The precursor for a Lemna light-harvesting chlorophyll a/b protein (pLHCP) has been synthesized in vitro from a single member of the nuclear LHCP multigene family. We report the sequence of this gene. When incubated with Lemna chloroplasts, the pLHCP is imported and processed into several polypeptides, and the mature form is assembled into the light-harvesting complex of photosystem II (LHC II). The accumulation of the processed LHCP is enhanced by the addition to the chloroplasts of a precursor and a co-factor for chlorophyll biosynthesis. Using a model for the arrangement of the mature polypeptide in the thylakoid membrane as a guide, we have created mutations that lie within the mature coding region. We have studied the processing, the integration into thylakoid membranes, and the assembly into light-harvesting complexes of six of these deletions. Four different mutant LHCPs are found as processed proteins in the thylakoid membrane, but only one appears to have an orientation in the membrane that is similar to that of the wild type. No mutant LHCP appears in LHC II. The other two mutant LHCPs cannot be detected within the chloroplasts. We conclude that stable complex formation is not required for the processing and insertion of altered LHCPs into the thylakoid membrane. We discuss the results in light of our model.
Risks of multimodal signaling: Bat predators attend to dynamic motion in frog sexual displays
Date: 2014-09-01
Creator: Wouter Halfwerk, Marjorie M. Dixon, Kristina J. Ottens, Ryan C. Taylor, Michael J., Ryan, Rachel A. Page, Patricia L. Jones
Access: Open access
- Many sexual displays contain multiple components that are received through a variety of sensory modalities. Primary and secondary signal components can interact to induce novel receiver responses and become targets of sexual selection as complex signals. However, predators can also use these complex signals for prey assessment, which may limit the evolution of elaborate sexual signals. We tested whether a multimodal sexual display of the male tĂșngara frog (Physalaemus pustulosus) increases predation risk from the fringe-lipped bat (Trachops cirrhosus) when compared with a unimodal display. We gave bats a choice to attack one of two frog models: a model with a vocal sac moving in synchrony with a mating call (multisensory cue), or a control model with the call but no vocal sac movement (unimodal cue). Bats preferred to attack the model associated with the multimodal display. Furthermore, we determined that bats perceive the vocal sac using echolocation rather than visual cues. Our data illustrate the costs associated with multimodal signaling and that sexual and natural selection pressures on the same trait are not always mediated through the same sensory modalities. These data are important when considering the role of environmental fluctuations on signal evolution as different sensory modalities will be differentially affected.
Bounding the number of cycles of O.D.E.S in Rn
Date: 2001-01-01
Creator: M. Farkas, P. Van Den Driessche, M. L. Zeeman
Access: Open access
- Criteria are given under which the boundary of an oriented surface does not consist entirely of trajectories of the C1 differential equation áș = f(x) in Rn. The special case of an annulus is further considered, and the criteria are used to deduce sufficient conditions for the differential equation to have at most one cycle. A bound on the number of cycles on surfaces of higher connectivity is given by similar conditions. ©2000 American Mathematical Society.
Hydrophobic core but not amino-terminal charged residues are required for translocation of an integral thylakoid membrane protein in vivo
Date: 1996-10-07
Creator: Benoit Baillet, Bruce D. Kohorn
Access: Open access
- The integral membrane protein cytochrome f contains an amino-terminal signal sequence that is required for translocation into the thylakoid membrane. The signal sequence contains a hydrophobic core neighbored by an amino-terminal charged residue. Mutations that introduce charged amino acids into the hydrophobic core are inhibitory to cytochrome f translocation, and thus render cells non-photosynthetic. We have isolated both nuclear and chloroplast suppressors of these mutations by selecting for restoration of photosynthetic growth of Chlamydomonas. Here we describe the characterization of two chloroplast, second site suppressor mutations. Both suppressors remove the positively charged amino acid that borders the amino terminus of the hydrophobic core, and replace this arginine with either a cysteine or a leucine. The existence of these suppressors suggests that the hydrophobic core can be shifted in position within the signal sequence, and analysis of triple mutants in the signal confirms this hypothesis. Thus this signal that mediates translocation into the thylakoid membrane is characterized by a hydrophobic region whose exact amino acid content is not critical, and that need not be flanked on its amino terminus by a charged residue.
An Arabidopsis serine/threonine kinase homologue with an epidermal growth factor repeat selected in yeast for its specificity for a thylakoid membrane protein
Date: 1992-01-01
Creator: Bruce D. Kohorn, Steven Lane, Tracy A. Smith
Access: Open access
- A number of molecules have recently been described that effect the correct transport and assembly of cytoplasmically synthesized proteins to cellular membranes. To identify proteins that bind or modify other proteins during the process of membrane translocation, we developed a yeast selection scheme that employs the yeast transcriptional activator GAL4. This selection facilitates the isolation of cDNAs that encode proteases and binding proteins for known target peptide sequences. We report the isolation of an Arabidopsis cDNA encoding a polypeptide that can interact with the amino terminus of a light-harvesting chlorophyll a/b-binding protein (LHCP), a cytoplasmically synthesized protein that is integral to the chloroplast thylakoid membrane. The cDNA was selected in yeast from an Arabidopsis expression library for its ability to inhibit a transcriptional activator GAL4-LHCP fusion protein, but not inhibit native GAL4 protein. The LHCP aminoterminal sequences included in the fusion protein are known to regulate LHCP biogenesis and function. The Arabidopsis cDNA encodes a 595-amino acid protein with at least two functional domains, one with similarity to the family of proteinserine/threonine kinases and another that contains an epidermal growth factor repeat. The identification of an EGF repeat in Arabidopsis indicates that the motif is conserved between the plant and animal kingdoms. Hybridization studies indicate that this gene is likely to be present in other genera of plants. Its mRNA is detected in green leaves but not in other plant tissues or in etiolated plants. The specificity in yeast and the expression pattern in plants together are suggestive of a role for this protein kinase in the assembly or regulation of LHCP.
Determination of the Relationship Between Peptoid Catalyst Oligomeric Length and Catalytic Enantioselectivity of Trifluoromethylation of Aldehydes Access to this record is restricted to members of the Bowdoin community. Log in here to view.
- Restriction End Date: 2025-06-01
Date: 2020-01-01
Creator: Katharine Toll
Access: Access restricted to the Bowdoin Community
Combinatorial properties of Thompson's group F
Date: 2004-07-01
Creator: Sean Cleary, Jennifer Taback
Access: Open access
- We study some combinatorial consequences of Blake Fordham's theorems on the word metric of Thompson's group F in the standard two generator presentation. We explore connections between the tree pair diagram representing an element w of F, its normal form in the infinite presentation, its word length, and minimal length representatives of it. We estimate word length in terms of the number and type of carets in the tree pair diagram and show sharpness of those estimates. In addition we explore some properties of the Cayley graph of F with respect to the two generator finite presentation. Namely, we exhibit the form of "dead end" elements in this Cayley graph, and show that it has no "deep pockets". Finally, we discuss a simple method for constructing minimal length representatives for strictly positive or negative words.
Role of SR-like RNA-binding protein 1 (Slr1) in hyphal tip localization of She3-transported mRNA in Candida albicans This record is embargoed.
- Embargo End Date: 2025-05-13
Date: 2020-01-01
Creator: Emma Beane
Access: Embargoed
Consequences of toxic secondary compounds in nectar for mutualist bees and antagonist butterflies
Date: 2016-10-01
Creator: Patricia L. Jones, Anurag A. Agrawal
Access: Open access
- Attraction of mutualists and defense against antagonists are critical challenges for most organisms and can be especially acute for plants with pollinating and non-pollinating flower visitors. Secondary compounds in flowers have been hypothesized to adaptively mediate attraction of mutualists and defense against antagonists, but this hypothesis has rarely been tested. The tissues of milkweeds (Asclepias spp.) contain toxic cardenolides that have long been studied as chemical defenses against herbivores. Milkweed nectar also contains cardenolides, and we have examined the impact of manipulating cardenolides in nectar on the foraging choices of two flower visitors: generalist bumble bees, Bombus impatiens, which are mutualistic pollinators, and specialist monarch butterflies, Danaus plexippus, which are herbivores as larvae and ineffective pollinators as adults. Although individual bumble bees in single foraging bouts showed no avoidance of cardenolides at the highest natural concentrations reported for milkweeds, a pattern of deterrence did arise when entire colonies were allowed to forage for several days. Monarch butterflies were not deterred by the presence of cardenolides in nectar when foraging from flowers, but laid fewer eggs on plants paired with cardenolide-laced flowers compared to controls. Thus, although deterrence of bumble bees by cardenolides may only occur after extensive foraging, a primary effect of nectar cardenolides appears to be reduction of monarch butterfly oviposition.
Bowdoin College - Medical School of Maine Catalogue (1911-1912)
Date: 1912-01-01
Access: Open access
- Bowdoin College Bulletin no. 37
Bowdoin College Catalogue (1914-1915)
Date: 1915-01-01
Access: Open access
- Bowdoin College Bulletin no. 56
Surface symmetries and PSL2(p)
Date: 2007-05-01
Creator: Murad Ăzaydin, Charlotte Simmons, Jennifer Taback
Access: Open access
- We classify, up to conjugacy, all orientation-preserving actions of PSL2(p) on closed connected orientable surfaces with spherical quotients. This classification is valid in the topological, PL, smooth, conformal, geometric and algebraic categories and is related to the Inverse Galois Problem. © 2006 American Mathematical Society.
Bowdoin College - Medical School of Maine Catalogue (1907-1908)
Date: 1908-01-01
Access: Open access
- Bowdoin College Bulletin no. 12
Social Learning Strategies: Bridge-Building between Fields
Date: 2018-07-01
Creator: Rachel L. Kendal, Neeltje J. Boogert, Luke Rendell, Kevin N. Laland, Mike, Webster, Patricia L. Jones
Access: Open access
- While social learning is widespread, indiscriminate copying of others is rarely beneficial. Theory suggests that individuals should be selective in what, when, and whom they copy, by following 'social learning strategiesâ (SLSs). The SLS concept has stimulated extensive experimental work, integrated theory, and empirical findings, and created impetus to the social learning and cultural evolution fields. However, the SLS concept needs updating to accommodate recent findings that individuals switch between strategies flexibly, that multiple strategies are deployed simultaneously, and that there is no one-to-one correspondence between psychological heuristics deployed and resulting population-level patterns. The field would also benefit from the simultaneous study of mechanism and function. SLSs provide a useful vehicle for bridge-building between cognitive psychology, neuroscience, and evolutionary biology.
Erratum: Context-dependent protein stabilization by methionine-to- leucine substitution shown in T4 lysozyme (Protein Science (November 3, 1998) 7:3 (772))
Date: 1998-01-01
Creator: L. A. Lipscomb, N. C. Gassner, S. D. Snow, A. M. Eldridge, W. A., Baase, D. L. Drew, B. W. Matthews
Access: Open access
Bowdoin College Catalogue (1928-1929)
Date: 1929-01-01
Access: Open access
- Bowdoin College Bulletin no. 178
Mitochondrial genotype influences the response to cold stress in the European green crab, Carcinus maenas
Date: 2019-01-01
Creator: Aidan F. Coyle, Erin R. Voss, Carolyn K. Tepolt, David B. Carlon
Access: Open access
- Hybrid zones provide natural experiments in recombination within and between genomes that may have strong effects on organismal fitness. On the East Coast of North America, two distinct lineages of the European green crab (Carcinus maenas) have been introduced in the last two centuries. These two lineages with putatively different adaptive properties have hybridized along the coast of the eastern Gulf of Maine, producing new nuclear and mitochondrial combinations that show clinal variation correlated with water temperature. To test the hypothesis that mitochondrial or nuclear genes have effects on thermal tolerance, we first measured the response to cold stress in crabs collected throughout the hybrid zone, then sequenced the mitochondrial CO1 gene and two nuclear single nucleotide polymorphisms (SNPs) representative of nuclear genetic lineage. Mitochondrial haplotype had a strong association with the ability of crabs to right themselves at 4.5°C that was sex specific: haplotypes originally from northern Europe gave male crabs an advantage while there was no haplotype effect on righting in female crabs. By contrast, the two nuclear SNPs that were significant outliers in a comparison between northern and southern C. maenas populations had no effect on righting response at low temperature. These results add C. maenas to the shortlist of ectotherms in which mitochondrial variation has been shown to affect thermal tolerance, and suggest that natural selection is shaping the structure of the hybrid zone across the Gulf of Maine. Our limited genomic sampling does not eliminate the strong possibility that mito-nuclear co-adaptation may play a role in the differences in thermal phenotypes documented here. Linkage between mitochondrial genotype and thermal tolerance suggests a role for local adaptation in promoting the spread of invasive populations of C. maenas around the world.
From Left to Right? White Evangelical Politicization, GOP Incorporation, and the Effect of Party Affiliation on Group Opinion Change
Date: 2013-05-01
Creator: Devon B Shapiro
Access: Open access
- While most white evangelicals in America have advocated moral, cultural, and social conservatism since the Founding, the groupâs fiscal and social welfare preferences have been more volatile. Early 20th century evangelicals tended to be socially conservative, fiscally liberal, and, to the extent that they were politicized, mostly Democratic partisans. Since that time, not only have white evangelicals abandoned the Democratic Party, but also they have largely become fiscal and social welfare conservatives. I attempt to explain that transformation. I first examine the dynamics of white evangelical politicization and GOP incorporation, providing social and historical context to the political and partisan calculations of white evangelicals since the 1970s. Further, I propose a party affiliation effect that helps to explain white evangelical fiscal and social welfare conservatism. This effect asserts that partisanship penetrates individual conceptions of political issues. In the case of white evangelicals, I argue that the group affiliated with the GOP largely on the basis of socio-moral issues and concerns. Partly as a result of that affiliation, group opinion on fiscal policy began to drift to the right, toward the Republican Party status quo. Consistent with this claim, I provide longitudinal analyses of ANES and GSS data that shed light on the timing of opinion changes. As we would expect, white evangelical opinion on economic issues was closer to Democratic partisans during the 1960s and moved moved toward Republicans during the 1980s-1990s.
Systemic Risk in the Airline Industry: Investigating the Effects of Network Interconnectedness on MES Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Angela Goldshteyn
Access: Access restricted to the Bowdoin Community
Isolation of nine microsatellite loci in Dolichogenidea homoeosomae (Hymenoptera) a parasitoid of the sunflower moth Homoeosoma electellum (Lepidoptera)
Date: 2006-03-01
Creator: Vladimir Douhovnikoff, Caterina Nerney, George K. Roderick, Craig H. Newton, Stephen C., Welter
Access: Open access
- Nine microsatellite loci were isolated from the insect Dolichogenidea homoeosomae (Hymenoptera: Braconidae), an important parasitoid of the sunflower moth Homosoeosoma electellum (Lepidoptera: Pyralidae), and assayed for polymorphism. All nine loci were polymorphic within the five populations tested, with two to 14 alleles per locus. Expected and observed heterozygosities ranged from 0.39 to 0.90 and 0.25 to 0.72 respectively. These are the first microsatellite primers developed for D. homeosomae and will be useful for studies of population dynamics and connectivity. © 2006 Blackwell Publishing Ltd.
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.
Assessment and Treatment of Pathological Skin Picking
Date: 2012-09-18
Creator: Jedidiah Siev, Hannah E. Reese, Kiara Timpano, Sabine Wilhelm
Access: Open access
- Pathological skin picking (PSP) refers to chronic skin picking or scratching that causes tissue damage and distress. It is a heterogeneous category of behaviors and may be manifest in the context of various psychological disorders. This chapter presents an overview of the empirical literature on the assessment and treatment of PSP, including (1) a cognitive-behavioral model as heuristic for conceptualizing treatment, (2) assessment tools, (3) a review of the pharmacological and psychosocial treatment outcome literatures, (4) cognitive-behavioral treatment techniques, and (5) future directions. The chapter is intended to introduce the clinician to the assessment and psychological tools used to treat PSP, as well as to provide impetus to advance research in this understudied domain.
Human Today, Posthuman Tomorrow in Margaret Atwood's MaddAddam Trilogy
Date: 2020-01-01
Creator: Benjamin Bousquet
Access: Open access
- Human Today, Posthuman Tomorrow explores the relationship between the human and the nonhuman in Margaret Atwoodâs MaddAddam trilogy through the lens of posthuman theory. Atwoodâs trilogy depicts a dystopian, anthropocentric world that hinges upon an apocalyptic, man-made epidemic known as the Waterless Flood. Through posthuman theory, this thesis looks at ways to reconcile the oppositional and hierarchical relationship between the human and the nonhuman. The thesis is split into three main chapters, each of which engages a different posthuman theory. The first chapter addresses the concept of hybridity as it is elaborated by Rosi Braidottiâs The Posthuman. Next, the thesis turns to Donna Harawayâs âThe Companion Species Manifestoâ to address the ways human-animal relations in the trilogy are imagined as mutual and non-hierarchical. The last chapter turns to the pigoon/human relationship through Gilles Deleuze and FĂ©lix Guattariâs concept of becoming to understand the ways in which humans and pigoons build a new, non-oppositional relationship. In all, this thesis works to understand the stakes of the trilogy through posthumanism to argue that only through a posthuman understanding of the world are we able to erode oppositional differences between humans and nonhumans and create a future inhabitable for all.
Nineteenth Century American Paintings at Bowdoin College
Date: 1974-01-01
Access: Open access
- Exhibition catalogue, Bowdoin College Museum of Art.
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.
Art in Craft Media: The Haystack Tradition, A Regional Exhibition from New England and New York
Date: 1981-01-01
Access: Open access
- Participating institutions: William Benton Museum of Art and others.
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.
Separation of internal and interaction dynamics for NLS-described wave packets with different carrier waves
Date: 2008-11-01
Creator: Martina Chirilus-Bruckner, Christopher Chong, Guido Schneider, Hannes Uecker
Access: Open access
- We give a detailed analysis of the interaction of two NLS-described wave packets with different carrier waves for a nonlinear wave equation. By separating the internal dynamics of each wave packet from the dynamics caused by the interaction we prove that there is almost no interaction of such wave packets. We also prove the validity of a formula for the envelope shift caused by the interaction of the wave packets. © 2008 Elsevier Inc. All rights reserved.
Seasonal acclimatization of antioxidants and photosynthesis in Chondrus crispus and Mastocarpus stellatus, two co-occurring red algae with differing stress tolerances
Date: 2004-01-01
Creator: Nissa L. Lohrmann, Barry A. Logan, Amy S. Johnson
Access: Open access
- Mastocarpus stellatus and Chondrus crispus are red macroalgae that co-dominate the lower rocky intertidal zones of the northern Atlantic coast. M. stellatus is more tolerant than C. crispus of environmental stresses, particularly those experienced during winter. This difference in tolerance has been attributed, in part, to greater contents or activities of certain antioxidants in M. stellatus. We compared the photosynthetic capacities and activities of three antioxidant enzymes - superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) - as well as the contents of ascorbate from fronds of M. stellatus and C. crispus collected over a year. Photosynthetic capacity increased in winter, but did not differ between species in any season. The activities of the three antioxidant enzymes and the contents of ascorbate were significantly greater in tissues collected during months with mean air and water temperatures below 7.5°C ("cold" months; December, February, March, April) than in months with mean air temperatures above 11°C ("warm" months; June, July, August, October). Overall, C. crispus had significantly greater SOD and APX activities, while M. stellatus had higher ascorbate contents. Species-specific differences in GR activity depended upon mean monthly temperatures at the time of tissue collection; C. crispus had higher activities during cold months, whereas M. stellatus had higher activities during warm months. Taken together, these data indicate that increased ROS scavenging capacity is a part of winter acclimatization; however, only trends in ascorbate content support the hypothesis that greater levels of antioxidants underlie the relatively greater winter tolerance of M. stellatus in comparison to C. crispus.
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
Bowdoin College Catalogue (1911-1912)
Date: 1912-01-01
Access: Open access
- Bowdoin College Bulletin no. 38
Origami-based impact mitigation via rarefaction solitary wave creation
Date: 2019-01-01
Creator: Hiromi Yasuda, Yasuhiro Miyazawa, Efstathios G. Charalampidis, Christopher Chong, Panayotis G., Kevrekidis, Jinkyu Yang
Access: Open access
- The principles underlying the art of origami paper folding can be applied to design sophisticated metamaterials with unique mechanical properties. By exploiting the flat crease patterns that determine the dynamic folding and unfolding motion of origami, we are able to design an origami-based metamaterial that can form rarefaction solitary waves. Our analytical, numerical, and experimental results demonstrate that this rarefaction solitary wave overtakes initial compressive strain waves, thereby causing the latter part of the origami structure to feel tension first instead of compression under impact. This counterintuitive dynamic mechanism can be used to create a highly efficient-yet reusable-impact mitigating system without relying on material damping, plasticity, or fracture.
Inbreeding shapes the evolution of marine invertebrates
Date: 2020-05-01
Creator: Kevin C. Olsen, Will H. Ryan, Alice A. Winn, Ellen T. Kosman, Jose A., Moscoso, Stacy A. Krueger-Hadfield, Scott C. Burgess, David B. Carlon, Richard K. Grosberg, Susan Kalisz, Don R. Levitan
Access: Open access
- Inbreeding is a potent evolutionary force shaping the distribution of genetic variation within and among populations of plants and animals. Yet, our understanding of the forces shaping the expression and evolution of nonrandom mating in general, and inbreeding in particular, remains remarkably incomplete. Most research on plant mating systems focuses on self-fertilization and its consequences for automatic selection, inbreeding depression, purging, and reproductive assurance, whereas studies of animal mating systems have often assumed that inbreeding is rare, and that natural selection favors traits that promote outbreeding. Given that many sessile and sedentary marine invertebrates and marine macroalgae share key life history features with seed plants (e.g., low mobility, modular construction, and the release of gametes into the environment), their mating systems may be similar. Here, we show that published estimates of inbreeding coefficients (FIS) for sessile and sedentary marine organisms are similar and at least as high as noted in terrestrial seed plants. We also found that variation in FIS within invertebrates is related to the potential to self-fertilize, disperse, and choose mates. The similarity of FIS for these organismal groups suggests that inbreeding could play a larger role in the evolution of sessile and sedentary marine organisms than is currently recognized. Specifically, associations between traits of marine invertebrates and FIS suggest that inbreeding could drive evolutionary transitions between hermaphroditism and separate sexes, direct development and multiphasic life cycles, and external and internal fertilization.
Increasing forest loss worldwide from invasive pests requires new trade regulations
Date: 2014-10-01
Creator: Bitty A. Roy, Helen M. Alexander, Jennifer Davidson, Faith T. Campbell, Jeremy J., Burdon, Richard Sniezko, Clive Brasier
Access: Open access
- Loss of forests due to non-native invasive pests (including insects, nematodes, and pathogens) is a global phenomenon with profound population, community, ecosystem, and economic impacts. We review the magnitude of pest-associated forest loss worldwide and discuss the major ecological and evolutionary causes and consequences of these invasions. After compiling and analyzing a dataset of pest invasions from 21 countries, we show that the number of forest pest invasions recorded for a given country has a significant positive relationship with trade (as indicated by gross domestic product) and is not associated with the amount of forested land within that country. We recommend revisions to existing international protocols for preventing pest entry and proliferation, including prohibiting shipments of non-essential plants and plant products unless quarantined. Because invasions often originate from taxa that are scientifically described only after their introduction, current phytosanitary regulations - which target specific, already named organisms - Are ineffective.
A simple polymerase chain reaction-based method for the construction of recombinase-mediated cassette exchange donor vectors
Date: 2008-11-01
Creator: Jack R. Bateman, C. Ting Wu
Access: Open access
- Here we describe a simple method for generating donor vectors suitable for targeted transgenesis via recombinase-mediated cassette exchange (RMCE) using the ΊC31 integrase. This PCR-based strategy employs small attB "tails" on the primers used to amplify a sequence of interest, permitting the rapid creation of transgenes for in vivo analysis. Copyright © 2008 by the Genetics Society of America.
Narrative, Identity, and Holocaust Memorialization in the United States
Date: 2020-01-01
Creator: Alexander Noah Kogan
Access: Open access
- Narratives at Holocaust memorials and museums in the United States connect the Holocaust to present-day identities and weave the Holocaust into American history. Holocaust narrativesââwhether at the universal, national, or local levelââdraw moral lessons from the past. These narratives and their moral lessons redefine what constitutes the Holocaust and are determined by the needs and sentiments of the present. The sites of remembrance in this thesis at once show the significance of the Holocaust in American identities at both national and local levels, as well as encourage an active remembrance of the past that restructures these identities. The type of active remembrance and its purpose differs at each site, but each encourages a reconsideration of the past to find potentially applicable lessons for the present.