Showing 3481 - 3490 of 5708 Items
Subleading-color contributions to gluon-gluon scattering in N = 4 SYM theory and relations to N = 8 supergravity
Date: 2008-11-01
Creator: Stephen G. Naculich, Horatiu Nastase, Howard J. Schnitzer
Access: Open access
- We study the subleading-color (nonplanar) contributions to the four-gluon scattering amplitudes in = 4 supersymmetric SU(N) Yang-Mills theory. Using the formalisms of Catani and of Sterman and Tejeda-Yeomans, we develop explicit expressions for the infrared-divergent contributions of all the subleading-color L-loop amplitudes up to three loops, and make some conjectures for the IR behavior for arbitrary L. We also derive several intriguing relations between the subleading-color one- and two-loop four-gluon amplitudes and the four-graviton amplitudes of = 8 supergravity. The exact one- and two-loop = 8 supergravity amplitudes can be expressed in terms of the one- and two-loop N-independent = 4 SYM amplitudes respectively, but the natural generalization to higher loops fails, despite having a simple interpretation in terms of the 't Hooft picture. We also find that, at least through two loops, the subleading-color amplitudes of = 4 SYM theory have uniform transcendentality (as do the leading-color amplitudes). Moreover, the = 4 SYM Catani operators, which express the IR-divergent contributions of loop amplitudes in terms of lower-loop amplitudes, are also shown to have uniform transcendentality, and to be the maximum transcendentality piece of the QCD Catani operators. © SISSA 2008.
French Visage: A Century and a Half of Portraiture and Caricature from the Artine Artinian Collection
Date: 1969-01-01
Creator: Richard V. West
Access: Open access
- Catalogue of an exhibition held at Bowdoin College Museum of Art.
Observations beyond the 2-year impact window
Date: 2021-01-01
Creator: José Edwards, Stephen Meardon
Access: Open access
- In 2018, Clarivate Analytics, publisher of the Web of Science Journal Citation Reports (JCR), suppressed publication of the 2017 Journal Impact Factor (JIF) for three of the four journals that it then indexed in the academic field of history of economics. Clarivate judged one of the journals, History of Economic Ideas (HEI), to be the “donor” of citations that distorted the impact factors of the European Journal of the History of Economic Thought (EJHET) and the Journal of the History of Economic Thought (JHET). The other journal, History of Political Economy (HOPE), was not included in that judgment. Our purpose is to define the JIF, summarize the controversy that gave rise to this symposium, and discuss methodologically and historically some of the problems with the use of citation indexes in general and the JIF in particular. We show how these problems pertain differently to the scholarly field of the history of economics than to economics in general. In so doing we also introduce the following five articles of this symposium.
Combining behavior and EEG to study the effects of mindfulness meditation on episodic memory
Date: 2020-05-01
Creator: Erika Nyhus, William A. Engel, Tomas Donatelli Pitfield, Isabella M.W. Vakkur
Access: Open access
- Although there has been recent interest in how mindfulness meditation can affect episodic memory as well as brain structure and function, no study has examined the behavioral and neural effects of mindfulness meditation on episodic memory. Here we present a protocol that combines mindfulness meditation training, an episodic memory task, and EEG to examine how mindfulness meditation changes behavioral performance and the neural correlates of episodic memory. Subjects in a mindfulness meditation experimental group were compared to a waitlist control group. Subjects in the mindfulness meditation experimental group spent four weeks training and practicing mindfulness meditation. Mindfulness was measured before and after training using the Five Facet Mindfulness Questionnaire (FFMQ). Episodic memory was measured before and after training using a source recognition task. During the retrieval phase of the source recognition task, EEG was recorded. The results showed that mindfulness, source recognition behavioral performance, and EEG theta power in right frontal and left parietal channels increased following mindfulness meditation training. In addition, increases in mindfulness correlated with increases in theta power in right frontal channels. Therefore, results obtained from combining mindfulness meditation training, an episodic memory task, and EEG reveal the behavioral and neural effects of mindfulness meditation on episodic memory.
Rapid oligo-galacturonide induced changes in protein phosphorylation in arabidopsis
Date: 2016-04-01
Creator: Bruce D. Kohorn, Divya Hoon, Benjamin B. Minkoff, Michael R. Sussman, Susan L., Kohorn
Access: Open access
- The wall-associated kinases (WAKs)1 are receptor protein kinases that bind to long polymers of cross-linked pectin in the cell wall. These plasma-membrane-associated protein kinases also bind soluble pectin fragments called oligo-galacturonides (OGs) released from the wall after pathogen attack and damage. WAKs are required for cell expansion during development but bind water soluble OGs generated from walls with a higher affinity than the wall-associated polysaccharides. OGs activate a WAKdependent, distinct stress-like response pathway to help plants resist pathogen attack. In this report, a quantitative mass-spectrometric-based phosphoproteomic analysis was used to identify Arabidopsis cellular events rapidly induced by OGs in planta. Using N14/ N15 isotopic in vivo metabolic labeling, we screened 1,000 phosphoproteins for rapid OG-induced changes and found 50 proteins with increased phosphorylation, while there were none that decreased significantly. Seven of the phosphosites within these proteins overlap with those altered by another signaling molecule plants use to indicate the presence of pathogens (the bacterial "elicitor" peptide Flg22), indicating distinct but overlapping pathways activated by these two types of chemicals. Genetic analysis of genes encoding 10 OG-specific and two Flg22/OG-induced phosphoproteins reveals that null mutations in eight proteins compromise the OG response. These phosphorylated proteins with genetic evidence supporting their role in the OG response include two cytoplasmic kinases, two membrane-associated scaffold proteins, a phospholipase C, a CDPK, an unknown cadmium response protein, and a motor protein. Null mutants in two proteins, the putative scaffold protein REM1.3, and a cytoplasmic receptor like kinase ROG2, enhance and suppress, respectively, a dominant WAK allele. Altogether, the results of these chemical and genetic experiments reveal the identity of several phosphorylated proteins involved in the kinase/ phosphatase-mediated signaling pathway initiated by cell wall changes.
Cell wall-associated kinases and pectin perception
Date: 2016-01-01
Creator: Bruce D. Kohorn
Access: Open access
- The pectin matrix of the angiosperm cell wall is regulated in both synthesis and modification and greatly influences the direction and extent of cell growth. Pathogens, herbivory and mechanical stresses all influence this pectin matrix and consequently plant form and function. The cell wall-associated kinases (WAKs) bind to pectin and regulate cell expansion or stress responses depending upon the state of the pectin. This review explores the WAKs in the context of cell wall biology and signal transduction pathways.
Increases in Theta Oscillatory Activity During Episodic Memory Retrieval Following Mindfulness Meditation Training
Date: 2019-09-04
Creator: Erika Nyhus, William Andrew Engel, Tomas Donatelli Pitfield, Isabella Marie Wang Vakkur
Access: Open access
- Mindfulness meditation has been shown to improve episodic memory and increase theta oscillations which are known to play a role in episodic memory retrieval. The present study examined the effect of mindfulness meditation on episodic memory retrieval and theta oscillations. Using a longitudinal design, subjects in the mindfulness meditation experimental group who underwent 4 weeks of mindfulness meditation training and practice were compared to a waitlist control group. During the pre-training and post-training experimental sessions, subjects completed the Five Facet Mindfulness Questionnaire (FFMQ) and studied adjectives and either imagined a scene (Place Task) or judged its pleasantness (Pleasant Task). During the recognition test, subjects decided which task was performed with each word (“Old Place Task” or “Old Pleasant Task”) or “New.” FFMQ scores and source discrimination were greater post-training than pre-training in the mindfulness meditation experimental group. Electroencephalography (EEG) results revealed that for the mindfulness meditation experimental group theta power was greater post-training than pre-training in right frontal and left parietal channels and changes in FFMQ scores correlated with changes in theta oscillations in right frontal channels (n = 20). The present results suggest that mindfulness meditation increases source memory retrieval and theta oscillations in a fronto-parietal network.
Uneven Increases in Racial Diversity of US Geoscience Undergraduates
Date: 2021-06-15
Creator: Rachel J. Beane, Eric M.D. Baer, Rowan Lockwood, R. Heather Macdonald, John, R., McDaris, Vernon R. Morris, I. Joshua Villalobos, Lisa D. White
Access: Open access
Assessing longitudinal pathways between maternal depressive symptoms, parenting self-esteem and infant temperament
Date: 2019-08-01
Creator: Lea Takács, Filip Smolík, Samuel Putnam
Access: Open access
- Background Previous studies of relations between parenting self-concepts, parental adjustment and child temperament have been ambiguous regarding the direction of influence; and have rarely followed families from pregnancy through the first year of life. The current study examines change and stability in maternal depressive symptoms, parenting competences and child temperament through the perinatal period until nine months postpartum. Methods Czech mothers (N = 282) participated at three time points: the third trimester of pregnancy (Time 1), six weeks (Time 2) and nine months postpartum (Time 3). Questionnaire data concerned depressive symptoms (T1, T2, T3), maternal parenting self-esteem (T1, T2) and sense of competence (T3), and child temperament (T2, T3). A path model was used to examine concurrent and longitudinal relations between these variables. Results The analyses indicated longitudinal stability of all constructs, as well as concurrent relations between them. Longitudinal relations supported child-to-parent, rather than parent-to-child, effects: child difficult temperament predicted decreases in perceived maternal parenting competences, but maternal variables did not predict change in infant temperament. In addition, we observed weak mutual relations between maternal depression levels and parenting competences, such that maternal depression diminished perceived parenting competences that in turn contributed to higher levels of depression. Conclusion Mothers’ confidence in their ability to parent is influenced by their experience with a difficult infant and by their depressive symptoms during the child’s first year of life. Depressive symptoms are, in turn, aggravated by mothers’ low perceived competences in the parenting role.