Showing 811 - 820 of 4695 Items
Midazolam-induced amnesia reduces memory for details and affects the ERP correlates of recollection and familiarity
Date: 2012-02-01
Creator: Erika Nyhus
Tim Curran
Access: Open access
- Dual process models suggest that recognition memory is supported by familiarity and recollection processes. Previous research administering amnesic drugs and measuring ERPs during recognition memory have provided evidence for separable neural correlates of familiarity and recollection. This study examined the effect of midazolam-induced amnesia on memory for details and the proposed ERP correlates of recognition. Midazolam or saline was administered while subjects studied oriented pictures of common objects. ERPs were recorded during a recognition test 1 day later. Subjects' discrimination of old and new pictures as well as orientation discrimination was worse when they were given midazolam instead of saline. As predicted, the parietal old/new effect was decreased with the administration of midazolam. However, weaker effects on FN400 old/new effects were also observed. These results provide converging pharmacological and electrophysiological evidence that midazolam primarily affects recollection as indexed by parietal ERP old/new effects and memory for orientation, while also exerting some weaker effects on familiarity as indexed by FN400 old/new effects. © 2011 Massachusetts Institute of Technology.
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.
Analytical representation of a black hole puncture solution
Date: 2007-03-13
Creator: Thomas W. Baumgarte
Stephen G. Naculich
Access: Open access
- The "moving-puncture" technique has led to dramatic advancements in the numerical simulations of binary black holes. Hannam et al. have recently demonstrated that, for suitable gauge conditions commonly employed in moving-puncture simulations, the evolution of a single black hole leads to a well-known, time-independent, maximal slicing of Schwarzschild spacetime. They construct the corresponding solution in isotropic coordinates numerically and demonstrate its usefulness, for example, for testing and calibrating numerical codes that employ moving-puncture techniques. In this brief report we point out that this solution can also be constructed analytically, making it even more useful as a test case for numerical codes. © 2007 The American Physical Society.
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.
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 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.
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.
Probing quantum Hall state homogeneity with surface waves
Date: 2013-01-01
Creator: M. E. Msall
W. Dietsche
S. Schmult
K. Von Klitzing
Access: Open access
- We study single quantum wells and matched density bilayer samples. Simultaneous measurements of the Hall voltages using low frequency lock-in techniques and of the changes in the 232 MHz (12.6 μm) SAW propagation measured with a vector network-analyzer allow comparison of the complex bulk and edge conductivities. The vtotal 1 bilayer state is seen directly in the SAW measurement only when the conductivity is below ∼ 6 × 10 -7 Siemens and is destroyed at moderate SAW powers by localized heating. The simultaneous reduction of the conductivity minima extracted from Hall data and from SAW data conclusively demonstrates that the vtotal 1 state disappears simultaneously throughout the bulk and not by the formation of competing domains or conducting filaments. © Published under licence by IOP Publishing Ltd.