Showing 171 - 180 of 733 Items
Neural inhibition enables selection during language processing
Date: 2010-09-21
Creator: Hannah R. Snyder, Natalie Hutchison, Erika Nyhus, Tim Curran, Marie T., Banich, Randall C. O'Reilly, Yuko Munakata
Access: Open access
- Whether grocery shopping or choosing words to express a thought, selecting between options can be challenging, especially for people with anxiety. We investigate the neural mechanisms supporting selection during language processing and its breakdown in anxiety. Our neural network simulations demonstrate a critical role for competitive, inhibitory dynamics supported by GABAergic interneurons. As predicted by our model, we find that anxiety (associated with reduced neural inhibition) impairs selection among options and associated prefrontal cortical activity, even in a simple, nonaffective verb-generation task, and the GABA agonist midazolam (which increases neural inhibition) improves selection, whereas retrieval from semantic memory is unaffected when selection demands are low. Neural inhibition is key to choosing our words.
BEING CAYLEY AUTOMATIC IS CLOSED under TAKING WREATH PRODUCT with VIRTUALLY CYCLIC GROUPS
Date: 2021-12-13
Creator: Dmitry Berdinsky, Murray Elder, Jennifer Taback
Access: Open access
- We extend work of Berdinsky and Khoussainov ['Cayley automatic representations of wreath products', International Journal of Foundations of Computer Science 27(2) (2016), 147-159] to show that being Cayley automatic is closed under taking the restricted wreath product with a virtually infinite cyclic group. This adds to the list of known examples of Cayley automatic groups.
The N = 2 U(N) gauge theory prepotential and periods from a perturbative matrix model calculation
Date: 2003-02-24
Creator: Stephen G. Naculich, Howard J. Schnitzer, Niclas Wyllard
Access: Open access
- We perform a completely perturbative matrix model calculation of the physical low-energy quantities of the N = 2 U(N) gauge theory. Within the matrix model framework we propose a perturbative definition of the periods a i in terms of certain tadpole diagrams, and check our conjecture up to first order in the gauge theory instanton expansion. The prescription does not require knowledge of the Seiberg-0Witten differential or curve.We also compute the N = 2 prepotential F(a) perturbatively up to the first-instanton level, finding agreement with the known result. 2002 Elsevier Science B.V. All rights reserved.
A note on convexity properties of Thompson's group F
Date: 2012-01-01
Creator: Matthew Horak, Melanie Stein, Jennifer Taback
Access: Open access
- We prove that Thompson's group F is not minimally almost convex with respect to any generating set which is a subset of the standard infinite generating set for F and which contains x1. We use this to show that F is not almost convex with respect to any generating set which is a subset of the standard infinite generating set, generalizing results in [4]. © Gruyter 2012.
Vacuum states of N =1* mass deformations of N =4 and N =2 conformal gauge theories and their brane interpretations
Date: 2001-08-27
Creator: Stephen G. Naculich, Howard J. Schnitzer, Niclas Wyllard
Access: Open access
- We find the classical supersymmetric vacuum states of a class of N =1* field theories obtained by mass deforming superconformal models with simple gauge groups and N =4 or N =2 supersymmetry. In particular, new classical vacuum states for mass-deformed N =4 models with Sp(2N) and SO(N) gauge symmetry are found. We also derive the classical vacua for various mass-deformed N =2 models with Sp(2N) and SU(N) gauge groups and antisymmetric (and symmetric) hypermultiplets. We suggest interpretations of the mass-deformed vacua in terms of three-branes expanded into five-brane configurations. © 2001 Elsevier Science B.V.
An Arabidopsis cell wall-associated kinase required for invertase activity and cell growth
Date: 2006-04-01
Creator: Bruce D. Kohorn, Masaru Kobayashi, Sue Johansen, Jeff Riese, Li Fen, Huang, Karen Koch, Sarita Fu, Anjali Dotson, Nicole Byers
Access: Open access
- The wall-associated kinases (WAK), a family of five proteins that contain extracellular domains that can be linked to pectin molecules of the cell wall, span the plasma membrane and have a cytoplasmic serine/threonine kinase domain. Previous work has shown that a reduction in WAK protein levels leads to a loss of cell expansion, indicating that these receptor-like proteins have a role in cell shape formation. Here it is shown that a single wak2 mutation exhibits a dependence on sugars and salts for seedling growth. This mutation also reduces the expression and activity of vacuolar invertase, often a key factor in turgor and expansion. WAKs may thus provide a molecular mechanism linking cell wall sensing (via pectin attachment) to regulation of solute metabolism, which in turn is known to be involved in turgor maintenance in growing cells. © 2006 The Authors.
Improved matrix-model calculation of the N = 2 prepotential
Date: 2004-04-01
Creator: Marta Gómez-Reino, Howard J. Schnitzer, Stephen G. Naculich
Access: Open access
- We present a matrix-model expression for the sum of instanton contributions to the prepotential of an N = 2 supersymmetric U (N) gauge theory, with matter in various representations. This expression is derived by combining the renormalization-group approach to the gauge theory prepotential with matrix-model methods. This result can be evaluated order-by-order in matrix-model perturbation theory to obtain the instanton corrections to the prepotential. We also show, using this expression, that the one-instanton prepotential assumes a universal form. © SISSA/ISAS 2004.
The use of Hardy-Weinberg Equilibrium in clonal plant systems
Date: 2016-02-01
Creator: Vladimir Douhovnikoff, Matthew Leventhal
Access: Open access
- Traditionally population genetics precludes the use of the same genetic individual more than once in Hardy-Weinberg (HW) based calculations due to the model's explicit assumptions. However, when applied to clonal plant populations this can be difficult to do, and in some circumstances, it may be ecologically informative to use the ramet as the data unit. In fact, ecologists have varied the definition of the individual from a strict adherence to a single data point per genotype to a more inclusive approach of one data point per ramet. With the advent of molecular tools, the list of facultatively clonal plants and the recognition of their ecological relevance grows. There is an important risk of misinterpretation when HW calculations are applied to a clonal plant not recognized as clonal, as well as when the definition of the individual for those calculations is not clearly stated in a known clonal species. Focusing on heterozygosity values, we investigate cases that demonstrate the extreme range of potential modeling outcomes and describe the different contexts where a particular definition could better meet ecological modeling goals. We emphasize that the HW model can be ecologically relevant when applied to clonal plants, but caution is necessary in how it is used, reported, and interpreted. We propose that in known clonal plants, both genotype (GHet) and ramet (RHet) based calculations are reported to define the full range of potential values and better facilitate cross-study comparisons.
Does differential receptor distribution underlie variable responses to a neuropeptide in the lobster cardiac system?
Date: 2021-08-02
Creator: Audrey J. Muscato, Patrick Walsh, Sovannarath Pong, Alixander Pupo, Roni J., Gross, Andrew E. Christie, J. Joe Hull, Patsy S. Dickinson
Access: Open access
- Central pattern generators produce rhythmic behaviors independently of sensory input; however, their outputs can be modulated by neuropeptides, thereby allowing for functional flexibility. We investigated the effects of C-type allatostatins (AST-C) on the cardiac ganglion (CG), which is the central pattern generator that controls the heart of the American lobster, Homarus americanus, to identify the biological mechanism underlying the significant variability in individual responses to AST-C. We proposed that the presence of multiple receptors, and thus differential receptor distribution, was at least partly responsible for this observed variability. Using transcriptome mining and PCR-based cloning, we identified four AST-C receptors (ASTCRs) in the CG; we then characterized their cellular localization, binding potential, and functional activation. Only two of the four receptors, ASTCR1 and ASTCR2, were fully functional GPCRs that targeted to the cell surface and were activated by AST-C peptides in our insect cell expression system. All four, however, were amplified from CG cDNAs. Following the confirmation of ASTCR expression, we used physiological and bioinformatic techniques to correlate receptor expression with cardiac responses to AST-C across individuals. Expression of ASTCR1 in the CG showed a negative correlation with increasing contraction amplitude in response to AST-C perfusion through the lobster heart, suggesting that the differential expression of ASTCRs within the CG is partly responsible for the specific physiological response to AST-C exhibited by a given individual lobster.
Assessment and comparison of putative amine receptor complement/diversity in the brain and eyestalk ganglia of the lobster, Homarus americanus
Date: 2020-06-01
Creator: Andrew E. Christie, J. Joe Hull, Patsy S. Dickinson
Access: Open access
- In decapods, dopamine, octopamine, serotonin, and histamine function as locally released/hormonally delivered modulators of physiology/behavior. Although the functional roles played by amines in decapods have been examined extensively, little is known about the identity/diversity of their amine receptors. Recently, a Homarus americanus mixed nervous system transcriptome was used to identify putative neuronal amine receptors in this species. While many receptors were identified, some were fragmentary, and no evidence of splice/other variants was found. Here, the previously predicted proteins were used to search brain- and eyestalk ganglia-specific transcriptomes to assess/compare amine receptor complements in these portions of the lobster nervous system. All previously identified receptors were reidentified from the brain and/or eyestalk ganglia transcriptomes, i.e., dopamine alpha-1, beta-1, and alpha-2 (Homam-DAα2R) receptors, octopamine alpha (Homam-OctαR), beta-1, beta-2, beta-3, beta-4, and octopamine–tyramine (Homam-OTR-I) receptors, serotonin type-1A, type-1B (Homam-5HTR1B), type-2B, and type-7 receptors; and histamine type-1 (Homam-HA1R), type-2, type-3, and type-4 receptors. For many previously partial proteins, full-length receptors were deduced from brain and/or eyestalk ganglia transcripts, i.e., Homam-DAα2R, Homam-OctαR, Homam-OTR-I, and Homam-5HTR1B. In addition, novel dopamine/ecdysteroid, octopamine alpha-2, and OTR receptors were discovered, the latter, Homam-OTR-II, being a putative paralog of Homam-OTR-I. Finally, evidence for splice/other variants was found for many receptors, including evidence for some being assembly-specific, e.g., a brain-specific Homam-OTR-I variant and an eyestalk ganglia-specific Homam-HA1R variant. To increase confidence in the transcriptome-derived sequences, a subset of receptors was cloned using RT-PCR. These data complement/augment those reported previously, providing a more complete picture of amine receptor complement/diversity in the lobster nervous system.