Showing 171 - 180 of 733 Items
Kernel functions on domains with hyperelliptic double
Date: 1977-01-01
Creator: William H. Barker
Access: Open access
- Iii this paper we show that the structure of the Bergman and Szegö kernel functions is especially simple on domains with hyperelliptic double. Each such domain is conformally equivalent to the exterior of a system of slits taken from the real axis, and on such domains the Bergman kernel function and its adjoint are essentially the same, while the Szegö kernel function and its adjoint are elementary and can be written in a closed form involving nothing worse than fourth roots of polynomials. Additionally, a number of applications of these results are obtained. © 1977 American Mathematical Society.
Attention training toward and away from threat in social phobia: Effects on subjective, behavioral, and physiological measures of anxiety
Date: 2012-01-01
Creator: Alexandre Heeren, Hannah E. Reese, Richard J. McNally, Pierre Philippot
Access: Open access
- Social phobics exhibit an attentional bias for threat in probe detection and probe discrimination paradigms. Attention training programs, in which probes always replace nonthreatening cues, reduce attentional bias for threat and self-reported social anxiety. However, researchers have seldom included behavioral measures of anxiety reduction, and have never taken physiological measures of anxiety reduction. In the present study, we trained individuals with generalized social phobia (n = 57) to attend to threat cues (attend to threat), to attend to positive cues (attend to positive), or to alternately attend to both (control condition). We assessed not only self-reported social anxiety, but also behavioral and physiological measures of social anxiety. Participants trained to attend to nonthreatening cues demonstrated significantly greater reductions in self-reported, behavioral, and physiological measures of anxiety than did participants from the attend to threat and control conditions. © 2011 Elsevier Ltd.
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.
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.
Sign Under the Domino Robinson-Schensted Maps
Date: 2014-01-01
Creator: Thomas Pietraho
Access: Open access
- We generalize a formula obtained independently by Reifegerste and Sjöstrand for the sign of a permutation under the classical Robinson-Schensted map to a family of domino Robinson-Schensted algorithms. © 2014 Springer Basel.
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.
Natural and experimental evolution of sexual conflict within Caenorhabditis nematodes
Date: 2015-05-22
Creator: Michael F. Palopoli, Colin Peden, Caitlin Woo, Ken Akiha, Megan, Ary, Lori Cruze, Jennifer L. Anderson, Patrick C. Phillips
Access: Open access
- Background: Although males and females need one another in order to reproduce, they often have different reproductive interests, which can lead to conflict between the sexes. The intensity and frequency of male-male competition for fertilization opportunities is thought to be an important contributor to this conflict. The nematode genus Caenorhabditis provides an opportunity to test this hypothesis because the frequency of males varies widely among species with different mating systems. Results: We find evidence that there is strong inter- and intra-sexual conflict within C. remanei, a dioecious species composed of equal frequencies of males and females. In particular, some C. remanei males greatly reduce female lifespan following mating, and their sperm have a strong competitive advantage over the sperm of other males. In contrast, our results suggest that both types of conflict have been greatly reduced within C. elegans, which is an androdioecious species that is composed of self-fertilizing hermaphrodites and rare males. Using experimental evolution in mutant C. elegans populations in which sperm production is blocked in hermaphrodites (effectively converting them to females), we find that the consequences of sexual conflict observed within C. remanei evolve rapidly within C. elegans populations experiencing high levels of male-male competition. Conclusions: Together, these complementary data sets support the hypothesis that the intensity of intersexual conflict varies with the intensity of competition among males, and that male-induced collateral damage to mates can evolve very rapidly within populations.
A semester-long project-oriented biochemistry laboratory based on Helicobacter pylori urease
Date: 2015-09-01
Creator: Kate R. Farnham, Danielle H. Dube
Access: Open access
- Here we present the development of a 13 week project-oriented biochemistry laboratory designed to introduce students to foundational biochemical techniques and then enable students to perform original research projects once they have mastered these techniques. In particular, we describe a semester-long laboratory that focuses on a biomedically relevant enzyme-Helicobacter pylori (Hp) urease-the activity of which is absolutely required for the gastric pathogen Hp to colonize the human stomach. Over the course of the semester, students undertake a biochemical purification of Hp urease, assess the success of their purification, and investigate the activity of their purified enzyme. In the final weeks of the semester, students design and implement their own experiments to study Hp urease. This laboratory provides students with an understanding of the importance of biochemistry in human health while empowering them to engage in an active area of research.
Post-coring entrapment of modern air in some shallow ice cores collected near the firn-ice transition: Evidence from CFC-12 measurements in Antarctic firn air and ice cores
Date: 2010-06-18
Creator: M. Aydin, S. A. Montzka, M. O. Battle, M. B. Williams, W. J., De Bruyn, J. H. Butler, K. R. Verhulst, C. Tatum, B. K. Gun, D. A. Plotkin, B. D. Hall, E. S. Saltzman
Access: Open access
- In this study, we report measurements of CFC-12 (CCl2F2) in firn air and in air extracted from shallow ice cores from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, some of the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for the presence of modern air entrapped in the shallow ice core samples that likely contained open pores at the time of collection. We propose that this is due to closure of the open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our results reveal that open porosity can exist below the maximum depth at which firn air samples can be collected, particularly at sites with lower accumulation rates. CFC-12 measurements demonstrate that post-drilling closure of open pores can lead to a change in the composition of bubble air in shallow ice cores through purely physical processes. The results have implications for investigations involving trace gas composition of bubbles in shallow ice cores collected near the firn-ice transition. © Author(s) 2010.