Search results for "Group theory"
showing 10 items of 703 documents
A note on a generalization of Françoise's algorithm for calculating higher order Melnikov functions
2004
In [J. Differential Equations 146 (2) (1998) 320–335], Françoise gives an algorithm for calculating the first nonvanishing Melnikov function M of a small polynomial perturbation of a Hamiltonian vector field and shows that M is given by an Abelian integral. This is done under the condition that vanishing of an Abelian integral of any polynomial form ω on the family of cycles implies that the form is algebraically relatively exact. We study here a simple example where Françoise’s condition is not verified. We generalize Françoise’s algorithm to this case and we show that M belongs to the C[log t, t, 1/t] module above the Abelian integrals. We also establish the linear differential system ver…
A note on higher order Melnikov functions
2005
We present several classes of planar polynomial Hamilton systems and their polynomial perturbations leading to vanishing of the first Melnikov integral. We discuss the form of higher order Melnikov integrals. In particular, we present new examples where the second order Melnikov integral is not an Abelian integral.
Automorphisms of hyperelliptic GAG-codes
2009
Abstract We determine the n –automorphism group of generalized algebraic-geometry codes associated with rational, elliptic and hyperelliptic function fields. Such group is, up to isomorphism, a subgroup of the automorphism group of the underlying function field.
Priming index of the Spanish word fragments from the Dasí, Soler, and Ruiz (2004) database
2007
Word-fragment completion is a frequently used test in implicit memory research. A database of 196 Spanish fragments was recently published (Dasi, Soler, & Ruiz, 2004) in which the fragments were described for indices, such as difficulty, familiarity, frequency, number of meanings, and so on (www.psychonomic.org/archive). In this work, a new index, thepriming index, is described for the same 196 fragments. This index is calculated for each fragment by subtracting the difficulty index (the proportion of correct completion when the fragment is not studied) from the proportion of correct completion when the fragment is studied, and it means the capacity of an item to be primed. In order to dete…
Do transposed-letter similarity effects occur at a morpheme level? Evidence for morpho-orthographic decomposition
2007
When does morphological decomposition occur in visual word recognition? An increasing body of evidence suggests the presence of early morphological processing. The present work investigates this issue via an orthographic similarity manipulation. Three masked priming lexical decision experiments were conducted to examine the transposed-letter similarity effect (e.g., jugde facilitates JUDGE more than the control jupbe) in polymorphemic and monomorphemic words. If morphological decomposition occurs at early stages of visual word recognition, we would expect an interaction with transposed-letter effects. Experiment 1 was carried out in Basque, which is an agglutinative language. The nonword pr…
Can colours be used to segment words when reading?
2015
Rayner, Fischer, and Pollatsek (1998, Vision Research) demonstrated that reading unspaced text in Indo-European languages produces a substantial reading cost in word identification (as deduced from an increased word-frequency effect on target words embedded in the unspaced vs. spaced sentences) and in eye movement guidance (as deduced from landing sites closer to the beginning of the words in unspaced sentences). However, the addition of spaces between words comes with a cost: nearby words may fall outside high-acuity central vision, thus reducing the potential benefits of parafoveal processing. In the present experiment, we introduced a salient visual cue intended to facilitate the process…
Difficulties of Drivers With Dyslexia When Reading Traffic Signs: Analysis of Reading, Eye Gazes, and Driving Performance
2018
A group of adult individuals with dyslexia and a matched group of normally reading individuals participated in a driving simulation experiment. Participants were asked to read the word presented on every direction traffic sign encountered along a route, as far as possible from the sign, maintaining driving performance. Word frequency and word length were manipulated as within-subject factors. We analyzed (a) reading accuracy, (b) how far the sign was when the participant started to give the response, (c) where the participant looked during the time leading up to the response, and (d) the variability of the vehicle’s speed during that time and during driving on similar segments of the route…
All Talk and No Action: A Transcranial Magnetic Stimulation Study of Motor Cortex Activation during Action Word Production
2004
AbstractA number of researchers have proposed that the premotor and motor areas are critical for the representation of words that refer to actions, but not objects. Recent evidence against this hypothesis indicates that the left premotor cortex is more sensitive to grammatical differences than to conceptual differences between words. However, it may still be the case that other anterior motor regions are engaged in processing a word's sensorimotor features. In the present study, we used singleand paired-pulse transcranial magnetic stimulation to test the hypothesis that left primary motor cortex is activated during the retrieval of words (nouns and verbs) associated with specific actions. W…
Efficacy and complications associated with a modified inferior alveolar nerve block technique. A randomized, triple-blind clinical trial
2014
Objectives: To compare the efficacy and complication rates of two different techniques for inferior alveolar nerve blocks (IANB). Study Design: A randomized, triple-blind clinical trial comprising 109 patients who required lower third molar removal was performed. In the control group, all patients received an IANB using the conventional Halsted technique, whereas in the experimental group, a modified technique using a more inferior injection point was performed. Results: A total of 100 patients were randomized. The modified technique group showed a significantly higher onset time in the lower lip and chin area, and was frequently associated to a lingual electric discharge sensation. Three f…
Is there a group effect? It depends on how you ask the question: Intraclass correlations for California Psychotherapy Alliance Scale–Group items.
2014
California Psychotherapy Alliance Scale-Group (CALPAS-G) data were collected from 1,138 group sessions attended by 248 group members in 16 counseling groups. Hierarchical linear modeling (HLM) was used to derive between-groups, between-member, and between-session variance components and intraclass correlation coefficients (ICCs) for the 12 CALPAS-G items. Using Ledermann and Kenny's (2012) descriptions of variable types, we examined differences in between-groups variance for the 6 CALPAS-G items classified as "Individual" items and the 6 CALPAS-G items classified as "Group" items. A Related-Samples Wilcoxon's Signed Ranked Test showed that the ICCs for the Group items were significantly lar…