Padé approximants for the acoustical properties of rigid frame porous media with pore size distributions

Expressions for the viscosity correction function, and hence bulk complex impedance, density, compressibility, and propagation constant, are obtained for a rigid frame porous medium whose pores are prismatic with fixed cross-sectional shape, but of variable pore size distribution. The lowand high-frequency behavior of the viscosity correction function is derived for the particular case of a log-normal pore size distribution, in terms of coefficients which can, in general, be computed numerically, and are given here explicitly for the particular cases of pores of equilateral triangular, circular, and slitlike cross-section. Simple approximate formulae, based on two-point Pade´ approximants for the viscosity correction function are obtained, which avoid a requirement for numerical integration or evaluation of special functions, and their accuracy is illustrated and investigated for the three pore shapes already mentioned

Padé approximants for the acoustical characteristics of rigid frame porous media

In this paper it is shown that a number of theoretical models of the acoustical properties of rigid frame porous media, especially those involving ratios of Bessel functions of complex argument, can be accurately approximated and greatly simplified by the use of Padé approximation techniques. In the case of the model of Attenborough [J. Acoust. Soc. Am. 81, 93–102 (1987)] rational approximations are produced for the characteristic impedance, propagation constant, dynamic compressibility, and dynamic density, as a function of frequency and the material parameters. The model proposed by Stinson and Champoux

The syntax-semantics of bare and definite plural subjects in the L2 Spanish of English natives

This study investigates the extent to which advanced native-English L2 learners of Spanish come to acquire restrictions on bare plural preverbal subjects in L2 Spanish (e.g. gatos “cats” vs. definite plurals such as los gatos “the cats”). It tests L2 knowledge of available semantic readings of bare plurals and definite plurals in Spanish, where [+specific] and [+generic] interpretations are syntactically represented differently from English. Assuming L1 transfer, and in view of a potential subset/superset relationship of the two grammars, the learning task in this domain is not a straightforward one. Target acquisition requires both grammatical expansion and retraction; Spanish definite plural subjects require the addition of an L1-unavailable [+generic] reading, while a loss of an L1-available [+generic] reading for preverbal subject bare plurals is required. The results and analysis show that advanced L2 learners of Spanish (English L1) can circumvent a superficial subset/superset learnability problem by means of feature resetting in line with the Nominal Mapping Parameter.

Poverty-of-the-stimulus and SLA epistemology: considering L2 knowledge of aspectual phrasal semantics

Coupling a review of previous studies on the acquisition of grammatical aspects undertaken from contrasting paradigmatic views of second language acquisition (SLA) with new experimental data from L2 Portuguese, the present study contributes to this specific literature as well as general debates in L2 epistemology. We tested 31 adult English learners of L2 Portuguese across three experiments, examining the extent to which they had acquired the syntax and (subtle) semantics of grammatical aspect. Demonstrating that many individuals acquired target knowledge of what we contend is a poverty-of-the-stimulus semantic entailment related to the checking of aspectual features encoded in Portuguese preterit and imperfect morphology, namely, a [±accidental] distinction that obtains in a restricted subset of contexts, we conclude that UG-based approaches to SLA are in a better position to tap and gauge underlying morphosyntactic competence, since based on independent theoretical linguistic descriptions, they make falsifiable predictions that are amenable to empirical scrutiny, seek to describe and explain beyond performance, and can account for L2 convergence on poverty-of-the-stimulus knowledge as well as L2 variability/optionality.

Optimal frame length for keeping normalized goodput with lowest requirement on BER

This paper presents an adaptive frame length mechanism based on a cross-layer analysis of intrinsic relations between the MAC frame length, bit error rate (BER) of the wireless link and normalized goodput. The proposed mechanism selects the optimal frame length that keeps the service normalized goodput at required levels while satisfying the lowest requirement on the BER, thus increasing the transmission reliability. Numerical results are provided and show that an optimal frame length satisfying the lowest BER requirement does indeed exist. The performance of BER requirement as a function of the MAC frame length is evaluated and compared for transmission scenarios with and without automatic repeat request (ARQ). Furthermore, issues related to the MAC overhead length are also discussed to illuminate the functionality and performance of the proposed mechanism.

When semantics aids phonology: a processing advantage for iconic word forms in aphasia

Iconicity is the non-arbitrary relation between properties of a phonological form and semantic content (e.g. “moo”, “splash”). It is a common feature of both spoken and signed languages, and recent evidence shows that iconic forms confer an advantage during word learning. We explored whether iconic forms conferred a processing advantage for 13 individuals with aphasia following left-hemisphere stroke. Iconic and control words were compared in four different tasks: repetition, reading aloud, auditory lexical decision and visual lexical decision. An advantage for iconic words was seen for some individuals in all tasks, with consistent group effects emerging in reading aloud and auditory lexical decision. Both these tasks rely on mapping between semantics and phonology. We conclude that iconicity aids spoken word processing for individuals with aphasia. This advantage may be due to a stronger connection between semantic information and phonological forms.

TOWARD SEMANTIC WEB SERVICES AS MVC APPLICATIONS: FROM OWL-S VIA UML

OWL-S is an application of OWL, the Web Ontology Language, that describes the semantics of Web Services so that their discovery, selection, invocation and composition can be automated. The research literature reports the use of UML diagrams for the automatic generation of Semantic Web Service descriptions in OWL-S. This paper demonstrates a higher level of automation by generating complete complete Web applications from OWL-S descriptions that have themselves been generated from UML. Previously, we proposed an approach for processing OWL-S descriptions in order to produce MVC-based skeletons for Web applications. The OWL-S ontology undergoes a series of transformations in order to generate a Model-View-Controller application implemented by a combination of Java Beans, JSP, and Servlets code, respectively. In this paper, we show in detail the documents produced at each processing step. We highlight the connections between OWL-S specifications and executable code in the various Java dialects and show the Web interfaces that result from this process.

Conservation laws and tachyon potentials in the sliver frame

Conservation laws have provided an elegant and efficient tool to evaluate the open string field theory interaction vertex, they have been originally implemented in the case where the string field is expanded in the Virasoro basis. In this work we derive conservation laws in the case where the string field is expanded in the so-called sliver L(0)-basis. As an application of this new set of conservation laws, we compute the open string field action relevant to the tachyon condensation and in order to present not only an illustration but also an additional information, we evaluate the action without imposing a gauge choice.

VSImG: A high frame rate bitmap based display system for neuroscience research

This paper describes a visual stimulus generator (VSImG) capable of displaying a gray-scale, 256 x 256 x 8 bitmap image with a frame rate of 500 Hz using a boustrophedonic scanning technique. It is designed for experiments with motion-sensitive neurons of the fly`s visual system, where the flicker fusion frequency of the photoreceptors can reach up to 500 Hz. Devices with such a high frame rate are not commercially available, but are required, if sensory systems with high flicker fusion frequency are to be studied. The implemented hardware approach gives us complete real-time control of the displacement sequence and provides all the signals needed to drive an electrostatic deflection display. With the use of analog signals, very small high-resolution displacements, not limited by the image`s pixel size can be obtained. Very slow image displacements with visually imperceptible steps can also be generated. This can be of interest for other vision research experiments. Two different stimulus files can be used simultaneously, allowing the system to generate X-Y displacements on one display or independent movements on two displays as long as they share the same bitmap image. (C) 2011 Elsevier B.V. All rights reserved.

Transcriptome analysis of Taenia solium cysticerci using Open Reading Frame ESTs (ORESTES)

Background: Human infection by the pork tapeworm Taenia solium affects more than 50 million people worldwide, particularly in underdeveloped and developing countries. Cysticercosis which arises from larval encystation can be life threatening and difficult to treat. Here, we investigate for the first time the transcriptome of the clinically relevant cysticerci larval form. Results: Using Expressed Sequence Tags (ESTs) produced by the ORESTES method, a total of 1,520 high quality ESTs were generated from 20 ORESTES cDNA mini-libraries and its analysis revealed fragments of genes with promising applications including 51 ESTs matching antigens previously described in other species, as well as 113 sequences representing proteins with potential extracellular localization, with obvious applications for immune-diagnosis or vaccine development. Conclusion: The set of sequences described here will contribute to deciphering the expression profile of this important parasite and will be informative for the genome assembly and annotation, as well as for studies of intra- and inter-specific sequence variability. Genes of interest for developing new diagnostic and therapeutic tools are described and discussed.