Showing 1941 - 1950 of 2040 Items
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
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.
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.
A super MHV vertex expansion for n=4 SYM theory
Date: 2009-07-06
Creator: Michael Kiermaier
Stephen G. Naculich
Access: Open access
- We present a supersymmetric generalization of the MHV vertex expansion for all tree amplitudes in = 4 SYM theory. In addition to the choice of a reference spinor, this super MHV vertex expansion also depends on four reference Grassmann parameters. We demonstrate that a significant fraction of diagrams in the expansion vanishes for a judicious choice of these Grassmann parameters, which simplifies the computation of amplitudes. Even pure-gluon amplitudes require fewer diagrams than in the ordinary MHV vertex expansion. We show that the super MHV vertex expansion arises from the recursion relation associated with a holomorphic all-line supershift. This is a supersymmetric generalization of the holomorphic all-line shift recently introduced in arXiv:0811.3624. We study the large-z behavior of generating functions under these all-line supershifts, and find that they generically provide 1/z k falloff at (Next-to) kMHV level. In the case of anti-MHV generating functions, we find that a careful choice of shift parameters guarantees a stronger 1/z k+4 falloff. These particular all-line supershifts may therefore play an important role in extending the super MHV vertex expansion to = 8 supergravity. © SISSA 2009.
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).
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.
Disruption of Thylakoid-associated Kinase 1 Leads to Alteration of Light Harvesting in Arabidopsis
Date: 2001-08-24
Creator: Shaun Snyders
Bruce D. Kohorn
Access: Open access
- To survive fluctuations in quality and intensity of light, plants and algae are able to preferentially direct the absorption of light energy to either one of the two photosystems PSI or PSII. This rapid process is referred to as a state transition and has been correlated with the phosphorylation and migration of the light-harvesting complex protein (LHCP) between PSII and PSI. We show here that thylakoid protein kinases (TAKs) are required for state transitions in Arabidopsis. Antisense TAK1 expression leads to a loss of LHCP phosphorylation and a reduction in state transitions. Preferential activation of PSII causes LHCP to accumulate with PSI, and TAK1 mutants disrupt this process. Finally, TAKs also influence the phosphorylation of multiple thylakoid proteins.
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.
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.
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.