N400-like potentials and reaction times index semantic relations between highly repeated individual words

The N400 ERP is an electrophysiological index of semantic processing. Its amplitude varies with the semantic category of words, their concreteness, or whether their meaning matches that of a preceding context. The results of a number of studies suggest that these effects could be markedly reduced or suppressed for stimuli that are repeated. Nevertheless, we have recently shown that significant effects of semantic matching and category could be obtained on N400-like potentials elicited by massively repeated target words in a prime–target semantic categorization task. If such effects could be obtained when primes also are repeated, it would then be possible to study the semantic associations between individual words. The present study thus aimed to test this hypothesis while (1) controlling for a potential contribution of physical matching to the processing of repeated targets and (2) testing if the N400-like effects obtained in these conditions are modulated by task instruction, as are classic N400 effects. Two category words were used as primes and two exemplars as targets. In one block of trials, subjects had to respond according to the semantic relation between prime and target (semantic instruction) and, in another block, they had to report changes in letter case (physical instruction). Results showed that the amplitude of the N400-like ERP obtained was modulated by semantic matching and category but not by letter case. The effect of semantic matching was observed only in the semantic instruction block. Interestingly, the effect of category was not modulated by task instruction. An independent component analysis showed that the component that made the greatest contribution to the effect of semantic matching in the time window of the N400-like potential had a scalp distribution similar to that reported for the N400 and was best fit as a bilateral generator in the superior temporal gyrus. The use of repetition could thus allow, at least in explicit semantic tasks, a drastic simplification of N400 protocols. Highly repeated individual words could be used to study semantic relations between individual concepts

Efficient Algorithms for Mixed Creative Telescoping

Creative telescoping is a powerful computer algebra paradigm -initiated by Doron Zeilberger in the 90's- for dealing with definite integrals and sums with parameters. We address the mixed continuous-discrete case, and focus on the integration of bivariate hypergeometric-hyperexponential terms. We design a new creative telescoping algorithm operating on this class of inputs, based on a Hermite-like reduction procedure. The new algorithm has two nice features: it is efficient and it delivers, for a suitable representation of the input, a minimal-order telescoper. Its analysis reveals tight bounds on the sizes of the telescoper it produces.Comment: To be published in the proceedings of ISSAC'1

Getting Punnishment Right: Do Costly Monitoring or Redustributive Punishment Help?

We introduce new treatments of a voluntary contribution mechanism with opportunities to punish, to see how contributions and punishments change when (a) each dollar lost in punishment must be awarded to another team member and/or when (b) obtaining information on individuals’ contributions is a costly choice. Conjectures that tying punishments to rewards might reduce punishment of high contributors (perverse punishment) or increase overall punishing are not completely born out, but innovation (a) nonetheless succeeds in making the net punishment of high contributors much less common because they receive enough rewards to offset punishment. A surprise finding is that innovation (b) also decreases the incidence of misdirected punishment, since high contributors do more monitoring than low ones while low contributors do most of the perverse punishing. Both innovations raise both contributions and earnings relative to the familiar VCM-with-punishment treatment.

Discrete ply model of circular pull-through test of fasteners in laminates

In aeronautical structures, assemblies with thin laminates are becoming increasingly usual, especially for fuselage design. In these structures, out-of-plane loads can appear in bolted joints and can lead to progressive punching of the fastener’s head in the laminate resulting, in some cases, in a failure mode called pull-through [1]. This complex phenomenon, which occurs in assemblies, was studied firstly by using a simplified ‘‘circular’’ pull-through test method. Qualitative micrographic examinations showed damage very similar to that observed in impacted specimens. The research presented here extends the Discrete Ply Model Method (DPM) developed by Bouvet et al. [2] to this case. The finite elements model is based on a particular mesh taking ply orientations into account. Cohesive elements are placed at the interfaces between solid elements to represent matrix cracks and delamination, thus allowing the natural coupling between these two damage modes to be represented. The model shows good correlation with test results, in terms of load/displacement curve, and correct prediction of the damage map until failure, including the splitting phenomenon

Torsion order of smooth projective surfaces

To a smooth projective variety $X$ whose Chow group of $0$-cycles is $\mathbf Q$-universally trivial one can associate its torsion index $\mathrm{Tor}(X)$, the smallest multiple of the diagonal appearing in a cycle-theoretic decomposition \`a la Bloch-Srinivas. We show that $\mathrm{Tor}(X)$ is the exponent of the torsion in the N\'eron-Severi-group of $X$ when $X$ is a surface over an algebraically closed field $k$, up to a power of the exponential characteristic of $k$.Comment: A few more minor changes in Colliot-Th\'el\`ene's appendi

X-ray structures of dinuclear copper(I) and polynuclear copper(II) complexes with the 2,4-bis(cyanamido)cyclobutane-1,3-dione dianion

From the 2,4-bis(cyanamido)cyclobutane-1,3-dione dianion (2,4-NCNsq2−), two copper complexes [Cu2(PPh3)4(PhCN)2(μ-2,4-NCNsq)] · PhCN (1) and [Cu(dien)(μ-2,4-NCNsq) · H2O]n (2) have been synthesized and characterized by IR and electronic absorption spectroscopies. Their structures have been determined by X-ray crystallography. Complex 1 is a dinuclear copper(I) compound with a 2,4-NCNsq2− ligand bridging two copper atoms through the nitrile nitrogen atoms. Complex 2 appears as a 3D network constituted of copper(II) atoms bridged by 2,4-NCNsq2− dianions. This complex presents an unexpected coordination mode of the bis(cyanamido) ligands which are both coordinated via the nitrile functions and via the amido nitrogen atoms of the NCN groups