Showing 5401 - 5450 of 5831 Items
Brain Networks Related to Beta Oscillatory Activityduring Episodic Memory Retrieval
Date: 2018-02-01
Creator: Erika Nyhus
Access: Open access
- Evidence from fMRI has consistently located a widespread network of frontal, parietal, and temporal lobe regions during episodic retrieval. However, the temporal limitations of the fMRI methodology have made it difficult to assess the transient network dynamics by which these distributed regions coordinate activity. Recent evidence suggests that beta oscillations (17-20 Hz) are important for top-down control for memory suppression. However, the spatial limitations of the EEG methodology make it difficult to assess the relationship between these oscillatory signals and the distributed networks identified with fMRI. This study used simultaneous EEG/fMRI to identify networks related to beta oscillations during episodic retrieval. Participants studied adjectives and either imagined a scene (Place Task) or judged its pleasantness (Pleasant Task). During the recognition test, participants decided which task was performed with each word (“Old Place Task” or “Old Pleasant Task”) or “New.” EEG results revealed that posterior beta power was greater for new than old words. fMRI results revealed activity in a frontal, parietal network that was greater for old than new words, consistent with prior studies. Although overall beta power increases correlated with decreased activity within a predominantly parietal network, within the right dorsolateral and ventrolateral pFC, beta power correlated with BOLD activity more under conditions requiring more cognitive control and EEG/fMRI effects in the right frontal cortex correlated with BOLD activity in a frontoparietal network. Therefore, using simultaneous EEG and fMRI, the present results suggest that beta oscillations are related to postretrieval control operations in the right frontal cortex and act within a broader postretrieval control network. © 2017 Massachusetts Institute of Technology.
Identifying a distinct developmental module in the zebrafish dentition
Date: 2018-01-01
Creator: Caleb Matthew Gordon
Access: Open access
- In the zebrafish pharynx, the first three teeth to form, 3V1, 4V1, and 5V1, have distinct adult and embryonic morphologies, suggesting that these teeth may form using different developmental pathways. Previous studies of gene expression profiles and mutant phenotypes in 3V1, 4V1, and 5V1 have identified four genes that might be involved in dissociating these tooth modules: pitx2b, eve1, pbx1a, and pbx1b. To determine how the developmental roles of these four genes differ across 3V1, 4V1, and 5V1, and obtain a better understanding of how these three teeth develop, I performed CRISPR/Cas9– mediated knockouts in each of these genes, or analyzed embryos from a stable transgenic mutant line where available, and observed the resulting tooth germs and mineralized tooth structures via fluorescence and confocal microscopy. Preliminary results implicate pitx2 as being required for tooth mineralization, offer a possible role for pbx1a, pbx1b, and eve1 in distinguishing the developmental pathway of 3V1, and suggest that 3V1 constitutes a distinct developmental module within the early ventral dentition.
Alpha modulation in younger and older adults during distracted
encoding
Date: 2022-06-01
Creator: Syanah C. Wynn, Erika Nyhus, Ole Jensen
Access: Open access
- To successfully encode information into long-term memory, we need top-down control to focus our attention on target stimuli. This attentional focus is achieved by the modulation of sensory neuronal excitability through alpha power. Failure to modulate alpha power and to inhibit distracting information has been reported in older adults during attention and working memory tasks. Given that alpha power during encoding can predict subsequent memory performance, aberrant oscillatory modulations might play a role in age-related memory deficits. However, it is unknown whether there are age-related differences in memory performance or alpha modulation when encoding targets with distraction. Here we show that both older and younger adults are able to encode targets paired with distractors and that the level of alpha power modulation during encoding predicted recognition success. Even though older adults showed signs of higher distractibility, this did not harm their episodic memory for target information. Also, we demonstrate that older adults only modulated alpha power during high distraction, both by enhancing target processing and inhibiting distractor processing. These results indicate that both younger and older adults are able to employ the same inhibitory control mechanisms successfully, but that older adults fail to call upon these when distraction is minimal. The findings of this study give us more insight into the mechanisms involved in memory encoding across the lifespan. © 2020 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
Effects of permafrost aggradation on peat properties as determined from a pan-Arctic synthesis of plant macrofossils
Date: 2016-01-01
Creator: C. C. Treat, M. C. Jones, P. Camill, A. Gallego-Sala, M., Garneau, J. W. Harden, G. Hugelius, E. S. Klein, U. Kokfelt, P. Kuhry, J. Loisel, P. J.H. Mathijssen, J. A. O'Donnell, P. O. Oksanen, T. M. Ronkainen, A. B.K. Sannel
Access: Open access
- Permafrost dynamics play an important role in high-latitude peatland carbon balance and are key to understanding the future response of soil carbon stocks. Permafrost aggradation can control the magnitude of the carbon feedback in peatlands through effects on peat properties. We compiled peatland plant macrofossil records for the northern permafrost zone (515 cores from 280 sites) and classified samples by vegetation type and environmental class (fen, bog, tundra and boreal permafrost, and thawed permafrost). We examined differences in peat properties (bulk density, carbon (C), nitrogen (N) and organic matter content, and C/N ratio) and C accumulation rates among vegetation types and environmental classes. Consequences of permafrost aggradation differed between boreal and tundra biomes, including differences in vegetation composition, C/N ratios, and N content. The vegetation composition of tundra permafrost peatlands was similar to permafrost-free fens, while boreal permafrost peatlands more closely resembled permafrost-free bogs. Nitrogen content in boreal permafrost and thawed permafrost peatlands was significantly lower than in permafrost-free bogs despite similar vegetation types (0.9% versus 1.5% N). Median long-term C accumulation rates were higher in fens (23 g C m yr ) than in permafrost-free bogs (18 g C m yr ) and were lowest in boreal permafrost peatlands (14 g C m yr ). The plant macrofossil record demonstrated transitions from fens to bogs to permafrost peatlands, bogs to fens, permafrost aggradation within fens, and permafrost thaw and reaggradation. Using data synthesis, we have identified predominant peatland successional pathways, changes in vegetation type, peat properties, and C accumulation rates associated with permafrost aggradation. -2 -1 -2 -1 -2 -1
The supply of media slant across outlets and demand for slant within outlets: Evidence from US presidential campaign news
Date: 2020-06-01
Creator: Marcel Garz, Gaurav Sood, Daniel F. Stone, Justin Wallace
Access: Open access
- We conduct across-outlet and within-outlet (and within-topic) analyses of “congenially” slanted news. We study “horse race” news (news on candidates' chances in an upcoming election) from six major online outlets for the 2012 and 2016 US presidential campaigns. We find robust evidence that horse race headlines were slanted congenially with respect to the preferences of the outlets' typical readers. However, evidence of congenial slant in the timing and frequency of horse race stories is weaker. We also find limited evidence of greater within-outlet demand for headlines most congenial to outlets' typical readers, and somewhat stronger evidence of greater demand for relatively uncongenial headlines. We discuss how various aspects of our results are consistent with each of the major mechanisms driving slant studied in the theoretical literature, and may help explain when each mechanism is more likely to come into play. In particular, readers may be more likely to click on uncongenial headlines due to inferring that these stories are particularly informative when they stand in contrast to an outlet's typically congenial slant.
Lake-landscape connections at the forest-tundra transition of northern Manitoba
Date: 2015-01-01
Creator: Charles E. Umbanhowar, Philip Camill, Mark B. Edlund, Christoph Geiss, Patrick, Henneghan, Kendra Passow
Access: Open access
- To better understand aquatic-terrestrial linkages in the sub-Arctic, and specifically the relative importance of landscape position versus land cover, we surveyed lakes, soils, land cover, and lake/basin characteristics in a 14000 km region of acidic forest-tundra landscape near northern Manitoba, Canada (59.56°N, 97.72°W) in 2009. We analyzed 39 different biological, chemical, and physical variables for lakes and soils. We used a remote-sensing-based classification to determine that the landscape was 21% water, 46% peat-forming lowland, and 24.9% open tundra, and we assigned lake order to all lakes based on the order of the outlet stream for each lake. Lakes were oligotrophic to mesotrophic (median total phosphorus: TP = 11.8 μg L ), N-limited (median dissolved inorganic nitrogen: TP = 1.6), acidic (median pH 5.7), and had moderate amounts of dissolved organic carbon (median DOC = 5.2 mg L ). We identified 2 principle groups of variables represented by DOC and conductivity/ cations, respectively, that captured major axes of lake variation. DOC, 2 measures of DOC quality (a /a [a proxy for molecular weight and aromaticity] and specific ultraviolet absorbance), and Fe and were significantly correlated with percent cover of lowland forest, but conductivity/cations were not correlated with variation in land cover. Soils were generally acidic (pH 2.7-4.4) and nutrient-poor, and wetland soils contained more carbon and higher concentrations of calcium, magnesium, and other cations than upland open tundra. Landscape position of lakes (measured as lake order) did not capture systematic differences in land cover or lake biogeochemistry. Our results highlight the importance of lowland export of DOC to lakes and further suggest the need for additional regional studies of aquatic-terrestrial connections in Arctic and sub-Arctic landscapes. 2 -1 -1 250 365
Assessment of temperament in children: Translation of instruments to portuguese (Brazil) language
Date: 2009-12-01
Creator: Vivian Caroline Klein, Samuel P. Putnam, Maria Beatriz Martins Linhares
Access: Open access
- International research has increasingly considered temperament as a relevant personal variable in child developmental pathways. The purpose of the present study was to describe the methodology for translation to Portuguese (Brazil) of three child temperament assessment instruments based on Rothbart's theoretical approach. An original translation was modified, based on feedback by two professional translators, three bilingual psychologists, and a sample of 15 Brazilian mothers. A backtranslation by a professional translator was then assessed by the authors of the original (English language) instruments. For the final version of the measure, authors of the original instrument judged that 100% of items were consistent with the original items, and a second sample of 15 Brazilian mothers identified no problems with the Portuguese items.
Measurement of fine-grained aspects of toddler temperament: The Early Childhood Behavior Questionnaire
Date: 2006-07-01
Creator: Samuel P. Putnam, Maria A. Gartstein, Mary K. Rothbart
Access: Open access
- This article describes the development, reliability, and factor structure of a finely differentiated (18 dimensions) parent-report measure of temperament in 1.5- to 3-year-old children, using a cross-sectional sample (N = 317) and a longitudinal sample of primary (N = 104) and secondary (N = 61) caregivers. Adequate internal consistency was demonstrated for all scales and moderate inter-rater reliability was evident for most scales. Longitudinal stability correlations were primarily large over 6- and 12-month spans and moderate to large from 18 to 36 months. Factor analysis revealed a three-factor structure of Surgency/Extraversion, Negative Affectivity, and Effortful Control. In both samples and for both primary and secondary caregivers, older children received higher scores for Attention Focusing, Discomfort, Inhibitory Control, and Positive Anticipation. Primary caregivers rated females higher in Fear, and lower in High-intensity Pleasure, than males; secondary caregivers rated females higher than males in several aspects of Effortful Control. © 2006 Elsevier Inc. All rights reserved.
Multistable solitons in the cubic-quintic discrete nonlinear Schrödinger equation
Date: 2006-04-01
Creator: R. Carretero-González, J. D. Talley, C. Chong, B. A. Malomed
Access: Open access
- We analyze the existence and stability of localized solutions in the one-dimensional discrete nonlinear Schrödinger (DNLS) equation with a combination of competing self-focusing cubic and defocusing quintic onsite nonlinearities. We produce a stability diagram for different families of soliton solutions that suggests the (co)existence of infinitely many branches of stable localized solutions. Bifurcations that occur with an increase in the coupling constant are studied in a numerical form. A variational approximation is developed for accurate prediction of the most fundamental and next-order solitons, together with their bifurcations. Salient properties of the model, which distinguish it from the well-known cubic DNLS equation, are the existence of two different types of symmetric solitons and stable asymmetric soliton solutions that are found in narrow regions of the parameter space. The asymmetric solutions appear from and disappear back into the symmetric ones via loops of forward and backward pitchfork bifurcations. © 2006 Elsevier Ltd. All rights reserved.
A relation for domino robinson-schensted algorithms
Date: 2010-01-01
Creator: Thomas Pietraho
Access: Open access
- We describe a map relating hyperoctahedral Robinson-Schensted algorithms on standard domino tableaux of unequal rank. Iteration of this map relates the algorithms defined by Garfinkle and Stanton-White and when restricted to involutions, this construction answers a question posed by van Leeuwen. The principal technique is derived from operations defined on standard domino tableaux by Garfinkle which must be extended to this more general setting. © Birkhäuser Verlag Basel/Switzerland 2009.
“I’m Going to Help You Become a Better You”: Teacher-Student Dynamics in Special Education
Date: 2019-05-01
Creator: Sophie Sadovnikoff
Access: Open access
- This study explores teachers’ roles in special education in terms of how they interact with students with disabilities. In the struggle against oppression and disempowerment, teachers can play a crucial role in employing education as the great equalizer, or else not. The question this research seeks to answer is: how do special education teachers interact with their students with disabilities, and how does this teacher role fit within a society that seeks to marginalize these students? I argue that special education teachers reproduce ableism by disciplining, normalizing, and controlling their students, but teachers express a deep sense of caring for and about their students, and understand their work as being their best effort at helping their students. The ableist actions that they perform are, ironically, an effort to help their students create fulfilling lives within an ableist society.
History lessons: The early development of intellectual property institutions in the United States
Date: 2001-01-01
Creator: B. Zorina Khan, Kenneth L. Sokoloff
Access: Open access
Political advertising in 2016: The presidential election as outlier?
Date: 2016-12-01
Creator: Erika Franklin Fowler, Travis N. Ridout, Michael M. Franz
Access: Open access
- The 2016 presidential campaign broke the mold when it comes to patterns of political advertising. Using data from the Wesleyan Media Project, we show the race featured far less advertising than the previous cycle, a huge imbalance in the number of ads across candidates and one candidate who almost ignored discussions of policy. This departure from past patterns, however, was not replicated at the congressional level. We draw some lessons about advertising from the 2016 campaign, suggesting that its seeming lack of effectiveness may owe to the unusual nature of the presidential campaign with one unconventional candidate and the other using an unconventional message strategy, among other non-advertising related factors.
On the sign representations for the complex reflection groups G(r, p, n)
Date: 2016-11-01
Creator: Aba Mbirika, Thomas Pietraho, William Silver
Access: Open access
- We present a formula for the values of the sign representations of a complex reflection group G(r, p, n) in terms of its image under a generalized Robinson–Schensted algorithm.
Structural strengthening of urchin skeletons by collagenous sutural ligaments
Date: 1998-01-01
Creator: Olaf Ellers, Amy S. Johnson, Philip E. Moberg
Access: Open access
- Sea urchin skeletons are strengthened by flexible collagenous ligaments that bind together rigid calcite plates at sutures. Whole skeletons without ligaments (removed by bleaching) broke at lower apically applied forces than did intact, fresh skeletons. In addition, in three-point bending tests on excised plate combinations, sutural ligaments strengthened sutures but not plates. The degree of sutural strengthening by ligaments depended on sutural position; in tensile tests, ambital and adapical sutures were strengthened more than adoral sutures. Adapical sutures, which grow fastest, were also the loosest, suggesting that strengthening by ligaments is associated with growth. In fed, growing urchins, sutures overall were looser than in unfed urchins. Looseness was demonstrated visually and by vibration analysis: bleached skeletons of unfed urchins rang at characteristic frequencies, indicating that sound traveled across tightly fitting sutures; skeletons of fed urchins damped vibrations, indicating loss of vibrational energy across looser sutures. Furthermore, bleached skeletons of fed urchins broke at lower apically applied forces than bleached skeletons of unfed urchins, indicating that the sutures of fed urchins had been held together relatively loosely by sutural ligaments. Thus, the apparently rigid dome-like skeleton of urchins sometimes transforms into a flexible, jointed membrane as sutures loosen and become flexible during growth.
Dark breathers in granular crystals
Date: 2013-04-08
Creator: C. Chong, P. G. Kevrekidis, G. Theocharis, Chiara Daraio
Access: Open access
- We present a study of the existence, stability, and bifurcation structure of families of dark breathers in a one-dimensional uniform chain of spherical beads under static load. A defocusing nonlinear Schrödinger equation (NLS) is derived for frequencies that are close to the edge of the phonon band and is used to construct targeted initial conditions for numerical computations. Salient features of the system include the existence of large amplitude solutions that emerge from the small amplitude solutions described by the NLS equation, and the presence of a nonlinear instability that, to the best of the authors' knowledge, has not been observed in classical Fermi-Pasta-Ulam lattices. Finally, it is also demonstrated that these dark breathers can be detected in a physically realistic experimental settings by merely actuating the ends of an initially at rest chain of beads and inducing destructive interference between their signals. © 2013 American Physical Society.
Ecotourism Reconsidered: Chinese and Western Participation in the Thai Elephant Industry
Date: 2019-05-01
Creator: Miao (Jasmine) Long
Access: Open access
Effects of Arabidopsis wall associated kinase mutations on ESMERALDA1 and elicitor induced ROS
Date: 2021-05-01
Creator: Bruce D. Kohorn, Bridgid E. Greed, Gregory Mouille, Stéphane Verger, Susan L., Kohorn
Access: Open access
- Angiosperm cell adhesion is dependent on interactions between pectin polysaccharides which make up a significant portion of the plant cell wall. Cell adhesion in Arabidopsis may also be regulated through a pectin-related signaling cascade mediated by a putative O-fucosyltransferase ESMERALDA1 (ESMD1), and the Epidermal Growth Factor (EGF) domains of the pectin binding Wall associated Kinases (WAKs) are a primary candidate substrate for ESMD1 activity. Genetic interactions between WAKs and ESMD1 were examined using a dominant hyperactive allele of WAK2, WAK2cTAP, and a mutant of the putative O-fucosyltransferase ESMD1. WAK2cTAP expression results in a dwarf phenotype and activation of the stress response and reactive oxygen species (ROS) production, while esmd1 is a suppressor of a pectin deficiency induced loss of adhesion. Here we find that esmd1 suppresses the WAK2cTAP dwarf and stress response phenotype, including ROS accumulation and gene expression. Additional analysis suggests that mutations of the potential WAK EGF O-fucosylation site also abate the WAK2cTAP phenotype, yet only evidence for an N-linked but not O-linked sugar addition can be found. Moreover, a WAK locus deletion allele has no effect on the ability of esmd1 to suppress an adhesion deficiency, indicating WAKs and their modification are not a required component of the potential ESMD1 signaling mechanism involved in the control of cell adhesion. The WAK locus deletion does however affect the induction of ROS but not the transcriptional response induced by the elicitors Flagellin, Chitin and oligogalacturonides (OGs).
A "Peculiarly American" Enthusiasm: George Bellows, Traditional Masculinity, and The Big Dory
Date: 2014-01-01
Creator: James W. Denison, IV
Access: Open access
- A “Peculiarly American” Enthusiasm: George Bellows, Traditional Masculinity, and The Big Dory investigates the portrayal of masculinity in the oeuvre of the much-lauded yet enigmatic American painter George Bellows (1882-1925). Rather than relying on Bellows’ urban works for source material, a significant portion of this investigation is conducted via a case study of Bellows’ 1913 panel The Big Dory, a scene of fishermen pushing a boat into the North Atlantic off Monhegan Island, Maine that the artist painted during a sojourn on the island in the months after his involvement in the landmark Armory Show in New York. The paper situates The Big Dory within the greater context of the history of the depiction of Maine through the lens of the heroic fisherman. Bellows achieved a heroic effect by forcing the viewer to focus on the labor of the fishermen via their positioning in the near middleground and by echoing the hues and forms of the men elsewhere in the painting, giving the work a sense of visual unity. I argue that these strategies highlight Bellows’ interest in tradition rather than modernism. Armed with this knowledge, Bellows’ other works come more sharply into focus. I reveal that the traditional heterosexual mode of white male identity Bellows represented in The Big Dory was not simply echoed in Bellows’ personal comportment, but in fact pervaded his oeuvre; such masculinity was a reaction by patriarchal American society against the perceived growth of other influences in the early twentieth century. The portrayal of such masculinity is then established as the key underlying feature of the sense of “Americanism” which has traditionally dominated reception of Bellows’ art.
Parterre: An Installation by Lauren Fensterstock
Date: 2008-01-01
Creator: Alison Ferris
Access: Open access
- Catalog of an exhibition held at the Bowdoin College Museum of Art from Oct. 3, 2008 through Jan.11, 2009. Essay by Alison Ferris.
Receptors and Neuropeptides in the Cardiac Ganglion of the American Lobster, Homarus americanus: A Bioinformatics and Mass Spectrometric Investigation
Date: 2019-01-01
Creator: Louis Mendez
Access: Open access
- Central pattern generators (CPGs) are neural networks that generate rhythmic motor patterns to allow organisms to perform stereotypical tasks, such as breathing, scratching, flying, and walking. The American lobster, Homarus americanus, is a simple model system whose CPGs are functionally analogous to those in vertebrate models and model complex rhythmic behaviors. CPGs in many Crustacea, including the American lobster, have been studied because of their ability to maintain biological function after isolation in physiologically relevant conditions. The cardiac ganglion (CG) is a CPG consisting of five larger motor neurons and four smaller pacemaker neurons that innervate the cardiac neuromuscular system and generate electrical bursts that drive patterned behaviors. Neuromodulators, such as neuropeptides, are known to modulate neural output in the CPGs of the American lobster. Currently, neuromodulators affecting the cardiac ganglia are thought to be mainly expressed and secreted outside of the cardiac ganglia, acting as extrinsic neuromodulators. However, there is current evidence to support the idea that neuromodulators can be intrinsically expressed within the cardiac ganglion of the American lobster. Preliminary studies using transcriptomic techniques on genomic and transcriptomic information indicate that neuropeptides are likely expressed within the cardiac ganglion. However, little research has been done to determine whether these neuropeptides are expressed in the cardiac ganglion of the American lobster. Therefore, the purpose of this study is to combine bioinformatics and mass spectrometric techniques to determine whether select neuropeptides are present in the cardiac ganglion within the cardiac neuromuscular system of the American lobster, Homarus americanus. Our data mining techniques using protein query sequences obtained from previously annotated brain and eyestalk transcriptomes resulted in the identification of 22 putative neuropeptides preprohormones from 17 neuropeptide families and 20 putative neuropeptide receptors from 17 neuropeptide receptor families in the CG transcriptome. Additionally, 9 putative neuropeptide receptors from 7 neuropeptide receptor families were detected in the cardiac muscle transcriptome. Of the 17 neuropeptide families detected, receptors for 9 of these neuropeptide families were detected in the CG transcriptome. Receptors for 6 of the neuropeptide families were also present in the cardiac muscle transcriptome. Interestingly, receptors for 6 of neuropeptide families detected were not found in either the CG or cardiac muscle transcriptomes, and receptors for 4 neuropeptide families that weren’t detected in the CG transcriptome were found in the cardiac muscle transcriptome. Therefore, our research suggests that neuropeptides are able to modulate CPG activity extrinsically, either though hormonal or local delivery, or intrinsically. Additionally, neuropeptides were extracted from the stomatogastric ganglion and the commissural ganglion using a scaled-down neuropeptide extraction protocol to estimate the number of tissues required to obtain sufficiently strong mass spectrometry signals. Pooled samples with two commissural ganglia and single samples of a commissural ganglion and a stomatogastric ganglion displayed little signal and an increase in larger peptides and impurities relative to single-tissue samples. Therefore, further optimization of the scaled-down neuropeptide extraction protocol must be done prior to analysis of a cardiac ganglion in the American lobster.
Forces generated during stretch in the heart of the lobster Homarus americanus are anisotropic and are altered by neuromodulators
Date: 2016-01-01
Creator: E. S. Dickinson, A. S. Johnson, O. Ellers, P. S. Dickinson
Access: Open access
- Mechanical and neurophysiological anisotropies mediate three-dimensional responses of the heart of Homarus americanus. Although hearts in vivo are loaded multi-axially by pressure, studies of invertebrate cardiac function typically use uniaxial tests. To generate whole-heart length-tension curves, stretch pyramids at constant lengthening and shortening rates were imposed uniaxially and biaxially along longitudinal and transverse axes of the beating whole heart. To determine whether neuropeptides that are known to modulate cardiac activity in H. americanus affect the active or passive components of these length-tension curves, we also performed these tests in the presence of SGRNFLRFamide (SGRN) and GYSNRNYLRFamide (GYS). In uniaxial and biaxial tests, both passive and active forces increased with stretch along both measurement axes. The increase in passive forces was anisotropic, with greater increases along the longitudinal axis. Passive forces showed hysteresis and active forces were higher during lengthening than shortening phases of the stretch pyramid. Active forces at a given length were increased by both neuropeptides. To exert these effects, neuropeptides might have acted indirectly on the muscle via their effects on the cardiac ganglion, directly on the neuromuscular junction, or directly on the muscles. Because increases in response to stretch were also seen in stimulated motor nerve-muscle preparations, at least some of the effects of the peptides are likely peripheral. Taken together, these findings suggest that flexibility in rhythmic cardiac contractions results from the amplified effects of neuropeptides interacting with the length-tension characteristics of the heart.
Elizabeth Peak: Prints and Drawings
Date: 1982-01-01
Access: Open access
- Exhibition held March 18-April 25, 1982 at Bowdoin College Museum of Art. Catalog by Alan Shestack.
"This is N.Y.C. Not Little Rock": The Battle to Integrate New York City's Public Schools
Date: 2019-01-01
Creator: Anne Fraser Gregory
Access: Open access
- The landmark Brown vs. Board of Education decision of 1954, and its subsequent implementation, offer an essential question: Are segregated schools inherently evil, and is integration the only solution to unequal education? The statistics that illustrate the effects of segregated schooling are indeed staggering. According to a 2016 Government Accountability Office study, the number of schools segregated along racial and economic lines doubled between 2000 and 2013. In New York City, the achievement gap between Black and white students has continued to grow. In 2018, the National Assessment of Achievement Progress reported that 48 percent of white fourth-graders were proficient in math, while only 16 percent of black students met the standard. With a gap of 32 percentage points—growing 5 points since 2015—Black children in New York are consistently behind their white peers in academics. Sixty years ago, New York's Black and Latino parents parents grappled with this same issue as they fought to desegregate the city’s schools. This Honors Project will discuss segregated schooling in New York City during the 1950s and 60s, and the actors who fought to disrupt the system. Throughout this work, I will attempt to illustrate the power of community in New York City, for both good and evil, for equality and bigotry. Parents—Black, white, and Puerto Rican—function as key players in this story, as they continually fought local and state Boards to access the education they believed to be rightfully theirs and their children’s. I will also assert the notion that segregation was not solely a Southern issue: the similarities between the fight for school integration in both North and South are striking, and highlight the far reaches of prejudice in the nation both then and now. Most importantly, I argue that unequal education may not be solved by integration alone, and that believing in integration as the only viable option perpetuates the incorrect notion that children of color require proximity to white students in order to be academically successful.
The Future Regained: Toward a Modernist Ethics of Time
Date: 2020-01-01
Creator: Jack Rodgers
Access: Open access
- This project explores the convergence of futurity and ethics through an examination of key figures in modernist literature. It studies works by Virginia Woolf, Marcel Proust, and James Joyce in order to conceptualize an encounter with the future which goes beyond a traditionally linear and teleological model of time, setting out to reimagine the role of both temporality and ethics in novels including Orlando, Mrs. Dalloway, In Search of Lost Time, and Ulysses. Key facets of this exploration, which is metaphorized and guided by the image of a window, include temporal otherness, transgression and fracturing of the self (primarily understood through the paradoxical experience of dying), and the arrival of the future into the present. Major theoretical influences include queer theory, poststructuralism, and anti-dialectics. Ultimately, the project makes the case that it is possible to construct a modernist ethics which embraces the messianic potential of absences, blanks, and blind spots, a proposition made possible by our encounter with an incomprehensible yet imminent fragment of the future out of place in the present. At the close, it suggests an ethical imperative towards “affirmative negation”—a messianic, annunciatory, affirmation of that which is missing or omitted.
Perception is key? Does perceptual sensitivity and parenting behavior predict children's reactivity to others’ emotions?
Date: 2017-11-01
Creator: Joyce Weeland, Alithe Van den Akker, Meike Slagt, Samuel Putnam
Access: Open access
- When interacting with other people, both children's biological predispositions and past experiences play a role in how they will process and respond to social–emotional cues. Children may partly differ in their reactions to such cues because they differ in the threshold for perceiving such cues in general. Theoretically, perceptual sensitivity (i.e., the amount of detection of slight, low-intensity stimuli from the external environment independent of visual and auditory ability) might, therefore, provide us with specific information on individual differences in susceptibility to the environment. However, the temperament trait of perceptual sensitivity is highly understudied. In an experiment, we tested whether school-aged children's (N = 521, 52.5% boys, Mage = 9.72 years, SD = 1.51) motor (facial electromyography) and affective (self-report) reactivities to dynamic facial expressions and vocalizations is predicted by their (parent-reported) perceptual sensitivity. Our results indicate that children's perceptual sensitivity predicts their motor reactivity to both happy and angry expressions and vocalizations. In addition, perceptual sensitivity interacted with positive (but not negative) parenting behavior in predicting children's motor reactivity to these emotions. Our findings suggest that perceptual sensitivity might indeed provide us with information on individual differences in reactivity to social–emotional cues, both alone and in interaction with parenting behavior. Because perceptual sensitivity focuses specifically on whether children perceive cues from their environment, and not on whether these cues cause arousal and/or whether children are able to regulate this arousal, it should be considered that perceptual sensitivity lies at the root of such individual differences.
Differential gene expression during compensatory plasticity in the prothoracic ganglion of the cricket, Gryllus bimaculatus Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Felicia F. Wang
Access: Access restricted to the Bowdoin Community
Images of the Madonna and Child by Three Tuscan Artists of the Early Seicento: Vanni, Roncalli, and Manetti
Date: 1986-01-01
Access: Open access
- Exhibition catalogue, Bowdoin College Museum of Art.
Tree-based language complexity of Thompson's group F
Date: 2015-11-01
Creator: Jennifer Taback, Sharif Younes
Access: Open access
- The definition of graph automatic groups by Kharlampovich, Khoussainov and Miasnikov and its extension to C-graph automatic by Elder and the first author raise the question of whether Thompson's group F is graph automatic. We define a language of normal forms based on the combinatorial "caret types", which arise when elements of F are considered as pairs of finite rooted binary trees. The language is accepted by a finite state machine with two counters, and forms the basis of a 3-counter graph automatic structure for the group.
Interaction of stretch feedback and beat regularity in response to AMGSEFLamide in the heart of Homarus americanus
Date: 2020-01-01
Creator: William Allen
Access: Open access
- Central pattern generators (CPGs) are neural circuits whose component neurons possess intrinsic properties and synaptic connections that allow them to generate rhythmic motor outputs in the absence of descending inputs. The cardiac ganglion (CG) is a nine-cell CPG located in the American lobster, Homarus americanus. Stretch of the myocardium feeds back to the CG through mechano-sensitive dendrites and is thought to play a role in maintaining regularity in the beating pattern of the heart. The novel peptide AMGSEFLamide has been observed to induce irregular beating patterns when applied at high concentrations. This study investigated the interaction between stretch-related feedback and AMGSEFLamide modulation in generating irregular beating patterns in the whole heart of Homarus americanus. It was hypothesized that greater longitudinal stretch of the heart would result in greater regularity in the instantaneous beat frequency, based on previous findings that stretch-sensitive dendrites play a role in the regulation of the heartbeat. Furthermore, it was predicted that the elimination of stretch feedback via deafferentation of the heart would augment the irregularity induced by AMGSEFLamide. Data showed significantly increased irregularity in beating in response to 10-6 M AMGSEFLamide application. Longitudinal stretch did not reliably alter baseline variability in frequency, nor did it influence the modulatory effect of AMGSEFLamide. Deafferentation did not significantly alter baseline irregularity. Deafferented preparations did exhibit a trend of responding to AMGSEFLamide with a greater percent increase in irregularity compared to when afferents were intact, suggesting a potential role of stretch-stabilization in response to modulatory perturbations in the Homarus heart.
Regulation of eyes absent gene expression in Drosophila melanogaster by Polycomb Group Response Elements 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: Boris S. Dimitrov
Access: Access restricted to the Bowdoin Community
Sensory-based niche partitioning in a multiple predator-multiple prey community
Date: 2015-05-20
Creator: Jay J. Falk, Hannah M. Ter Hofstede, Patricia L. Jones, Marjorie M. Dixon, Paul A., Faure, Elisabeth K.V. Kalko, Rachel A. Page
Access: Open access
- Many predators and parasites eavesdrop on the communication signals of their prey. Eavesdropping is typically studied as dyadic predator-prey species interactions; yet in nature, most predators target multiple prey species and most prey must evade multiple predator species. The impact of predator communities on prey signal evolution is not well understood. Predators could converge in their preferences for conspicuous signal properties, generating competition among predators and natural selection on particular prey signal features. Alternatively, predator species could vary in their preferences for prey signal properties, resulting in sensory-based niche partitioning of prey resources. In the Neotropics, many substrate-gleaning bats use the mate-attraction songs of male katydids to locate them as prey. We studied mechanisms of niche partitioning in four substrate- gleaning bat species and found they are similar in morphology, echolocation signal design and prey-handling ability, but each species preferred different acoustic features of male song in 12 sympatric katydid species. This divergence in predator preference probably contributes to the coexistence of many substrate-gleaning bat species in the Neotropics, and the substantial diversity in the mate-attraction signals of katydids. Our results provide insight into how multiple eavesdropping predator species might influence prey signal evolution through sensory-based niche partitioning.