Bi-sensory, striped representations: comparative insights from owl and platypus

Bi-sensory striped arrays are described in owl and platypus that share some similarities with the other variant of bi-sensory striped array found in primate and carnivore striate cortex: ocular dominance columns. Like ocular dominance columns, the owl and platypus striped systems each involve two different topographic arrays that are cut into parallel stripes, and interdigitated, so that higher-order neurons can integrate across both arrays. Unlike ocular dominance stripes, which have a separate array for each eye, the striped array in the middle third of the owl tectum has a separate array for each cerebral hemisphere. Binocular neurons send outputs from both hemispheres to the striped array where they are segregated into parallel stripes according to hemisphere of origin. In platypus primary somatosensory cortex (SI), the two arrays of interdigitated stripes are derived from separate sensory systems in the bill, 40,000 electroreceptors and 60,000 mechanoreceptors. The stripes in platypus SI cortex produce bimodal electrosensory-mechanosensory neurons with specificity for the time-of-arrival difference between the two systems. This thunder-and-lightning system would allow the platypus to estimate the distance of the prey using time disparities generated at the bill between the earlier electrical wave and the later mechanical wave caused by the motion of benthic prey. The functional significance of parallel, striped arrays is not clear, even for the highly-studied ocular dominance system, but a general strategy is proposed here that is based on the detection of temporal disparities between the two arrays that can be used to estimate distance. (C) 2004 Elsevier Ltd. All rights reserved.

Mesoscopic one-way channels for quantum state transfer via the quantum hall effect

We show that the one-way channel formalism of quantum optics has a physical realization in electronic systems. In particular, we show that magnetic edge states form unidirectional quantum channels capable of coherently transporting electronic quantum information. Using the equivalence between one-way photonic channels and magnetic edge states, we adapt a proposal for quantum state transfer to mesoscopic systems using edge states as a quantum channel, and show that it is feasible with reasonable experimental parameters. We discuss how this protocol may be used to transfer information encoded in number, charge, or spin states of quantum dots, so it may prove useful for transferring quantum information between parts of a solid-state quantum computer

Magic-angle effects in the interlayer magnetoresistance of quasi-one-dimensional metals due to interchain incoherence

The dependence of the magnetoresistance of quasi-one-dimensional metals on the direction of the magnetic field show dips when the field is tilted at the so-called magic angles determined by the structural dimensions of the materials. There is currently no accepted explanation for these magic-angle effects. We present a possible explanation. Our model is based on the assumption that, the intralayer transport in the second most conducting direction has a small contribution from incoherent electrons. This incoherence is modeled by a small uncertainty in momentum perpendicular to the most conducting (chain) direction. Our model predicts the magic angles seen in interlayer transport measurements for different orientations of the field. We compare our results to predictions by other models and to experiment.

Mixed order parameters, accidental nodes and broken time reversal symmetry in organic superconductors: a group theoretical analysis

We present a group theoretical analysis of several classes of organic superconductor. We predict that highly frustrated organic superconductors, such as K-(ET)(2)Cu-2(CN)(3) (where ET is BEDT-TTF, bis(ethylenedithio) tetrathiafulvalene) and beta'-[Pd(dmit)(2)](2)X, undergo two superconducting phase transitions, the first from the normal state to a d-wave superconductor and the second to a d + id state. We show that the monoclinic distortion of K-(ET)(2)Cu(NCS)(2) means that the symmetry of its superconducting order parameter is different from that of orthorhombic-K-(ET)(2)Cu[N(CN)(2)] Br. We propose that beta'' and theta phase organic superconductors have d(xy) + s order parameters.

Excitation spectra of the spin-1/2 triangular-lattice Heisenberg antiferromagnet

We use series expansion methods to calculate the dispersion relation of the one-magnon excitations for the spin-(1)/(2) triangular-lattice nearest-neighbor Heisenberg antiferromagnet above a three-sublattice ordered ground state. Several striking features are observed compared to the classical (large-S) spin-wave spectra. Whereas, at low energies the dispersion is only weakly renormalized by quantum fluctuations, significant anomalies are observed at high energies. In particular, we find rotonlike minima at special wave vectors and strong downward renormalization in large parts of the Brillouin zone, leading to very flat or dispersionless modes. We present detailed comparison of our calculated excitation energies in the Brillouin zone with the spin-wave dispersion to order 1/S calculated recently by Starykh, Chubukov, and Abanov [Phys. Rev. B74, 180403(R) (2006)]. We find many common features but also some quantitative and qualitative differences. We show that at temperatures as low as 0.1J the thermally excited rotons make a significant contribution to the entropy. Consequently, unlike for the square lattice model, a nonlinear sigma model description of the finite-temperature properties is only applicable at temperatures < 0.1J. Finally, we review recent NMR measurements on the organic compound kappa-(BEDT-TTF)(2)Cu-2(CN)(3). We argue that these are inconsistent with long-range order and a description of the low-energy excitations in terms of interacting magnons, and that therefore a Heisenberg model with only nearest-neighbor exchange does not offer an adequate description of this material.

Experiments with Bose-Einstein condensates on an atom chip

We describe the production of BECs on a new type of atom chip based on silver foil. Our atom chip is fabricated with thick wires capable of carrying currents of several amperes without overheating. The silver surface is highly reflective to light resonant with optical transitions used for Rb. The pattern on the chip consists of two parallel Z-trap wires, capable of producing two-wire guide, and two additional endcap wires for varying the axial confinement. Condensates are produced in magnetic microtraps formed within 1 mm of surface of the chip. We have observed the fragmentation of cold atom clouds when brought close to the chip surface. This results from a perturbed trapping potential caused by nanometer deviations of the current path through the wires on the chip. We present results of fragmentation of cold clouds at distances below 100 µm from the wires and investigate the origin of the deviating current. The fragmentation has different characteristics to those seen with copper conductors. The dynamics of atoms in these microtraps is also investigated. ©2005 COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The detection and identification of extraneous metals in material conveyance systems

The aim of this work was to design and build an equipment which can detect ferrous and non-ferrous objects in conveyed commodities, discriminate between them and locate the object along the belt and on the width of the belt. The magnetic induction mechanism was used as a means of achieving the objectives of this research. In order to choose the appropriate geometry and size of the induction field source, the field distributions of different source geometries and sizes were studied in detail. From these investigations it was found the square loop geometry is the most appropriate as a field generating source for the purpose of this project. The phenomena of field distribution in the conductors was also investigated. An equipment was designed and built at the preliminary stages of thework based on a flux-gate magnetometer with the ability to detect only ferrous objects.The instrument was designed such that it could be used to detect ferrous objects in the coal conveyors of power stations. The advantages of employing this detector in the power industry over the present ferrous metal electromagnetic separators were also considered. The objectives of this project culminated in the design and construction of a ferrous and non-ferrous detector with the ability to discriminate between ferrous and non-ferrous metals and to locate the objects on the conveying system. An experimental study was carried out to test the performance of the equipment in the detection of ferrous and non-ferrous objects of a given size carried on the conveyor belt. The ability of the equipment to discriminate between the types of metals and to locate the object on the belt was also evaluated experimentally. The benefits which can be gained from the industrial implementations of the equipment were considered. Further topics which may be investigated as an extension of this work are given.

Developments and extensions of Roth's method of double Fourier series with applications to the solution of electromagnetic field problems

The first part of the thesis compares Roth's method with other methods, in particular the method of separation of variables and the finite cosine transform method, for solving certain elliptic partial differential equations arising in practice. In particular we consider the solution of steady state problems associated with insulated conductors in rectangular slots. Roth's method has two main disadvantages namely the slow rate of con­vergence of the double Fourier series and the restrictive form of the allowable boundary conditions. A combined Roth-separation of variables method is derived to remove the restrictions on the form of the boundary conditions and various Chebyshev approximations are used to try to improve the rate of convergence of the series. All the techniques are then applied to the Neumann problem arising from balanced rectangular windings in a transformer window. Roth's method is then extended to deal with problems other than those resulting from static fields. First we consider a rectangular insulated conductor in a rectangular slot when the current is varying sinusoidally with time. An approximate method is also developed and compared with the exact method.The approximation is then used to consider the problem of an insulated conductor in a slot facing an air gap. We also consider the exact method applied to the determination of the eddy-current loss produced in an isolated rectangular conductor by a transverse magnetic field varying sinusoidally with time. The results obtained using Roth's method are critically compared with those obtained by other authors using different methods. The final part of the thesis investigates further the application of Chebyshdev methods to the solution of elliptic partial differential equations; an area where Chebyshev approximations have rarely been used. A poisson equation with a polynomial term is treated first followed by a slot problem in cylindrical geometry.

Intercultural transfer and artistic innovation:German musicians in Victorian Britain

Throughout the nineteenth century, German classical music production was an aesthetic point of reference for British concert audiences. As a consequence, a sizeable number of German musicians were to be found in Britain as performers, conductors, teachers, musicologists and managers. They acted as agents of intercultural transfer, disseminating performance and organisational practices which had a transformative effect on British musical life. This article moves away from a focus on high-profile visiting artists such as Mendelssohn Bartholdy or Wagner and argues that the extent to which transfer took place can be better assessed by concentrating on the cohort of those artists who remained permanently. Some of these are all but forgotten today, but were household names in Victorian Britain. The case studies have been selected for the range of genres they represent and include Joseph Mainzer (choral singing), Carl Rosa (opera), August Manns, Carl Hallé and Julius Seligmann (orchestral music), and Friedrich Niecks (musicology). On a theoretical level, the concept of ‘intercultural transfer’ is applied in order to determine aspects such as diffusion, adaptation or sustainability of artistic elements within the new cultural context. The approach confirms that ‘national’ cultures do not develop indigenously but always through cross-national interaction. Während des neunzehnten Jahrhunderts war die klassische Musikszene Deutschlands ästhetischer Bezugpunkt für das britische Konzertpublikum. Dies hatte zur Folge, dass vermehrt Deutsche als Musiker, Dirigenten, Lehrer, Musikwissenschaftler und Manager in Großbritannien tätig wurden. Sie fungierten als Vermittler interkulturellen Transfers, indem sie aufführungs- und organisationstechnische Praktiken verbreiteten und damit zu einer Transformation des britischen Musiklebens beitrugen. Vorliegender Artikel konzentriert sich weniger auf bekannte Künstler mit kurzfristigen Engagements (z. B. Mendelssohn Bartholdy, Wagner), und argumentiert vielmehr, dass sich das Ausmaß des Transfers besser über solche Musiker feststellen lässt, die sich längerfristig ansiedelten. Einige davon waren allgemein bekannte Persönlichkeiten im Königreich, sind heute aber vergessen. Die Auswahl der Fallstudien gibt einen Überblick über verschiedene Gattungen und beinhaltet Joseph Mainzer (Chorgesang), Carl Rosa (Oper), August Manns, Carl Hallé und Julius Seligmann (Orchestermusik), sowie Friedrich Niecks (Musikwissenschaft). Auf der Theorieebene wird das Konzept des ‘interkulturellen Transfers’ herangezogen, um Aspekte wie Diffusion, Anpassung oder Nachhaltigkeit künstlerischer Elemente im neuen kulturellen Kontext zu beleuchten. Der Ansatz bestätigt, dass sich ‘nationale’ Kulturen nicht indigen entwickeln sondern immer im Austausch mit anderen Kulturen

Perspective work on optical fibre sensors

Optical fibre based sensors are transforming industry by permitting monitoring in hitherto inaccessible environments or measurement approaches that cannot be reproduced using conventional electronic sensors. A multitude of techniques have been developed to render the fibres sensitive to a wide range of parameters including: temperature, strain, pressure (static and dynamic), acceleration, rotation, gas type, and specific biochemical species. Constructed entirely of glass or polymer material, optical fibre devices like fibre gratings offer the properties: low loss, dielectric construction, small size, multiplexing, and so on [1-3]. In this paper, the authors will show the latest developing industrial applications, using polymer optical fibre (POF) devices, and comparing their performance with silica optical fibre devices. The authors address two pressing commercial requirements. The first concerns the monitoring of fuel level in civil aircraft. There is a strong motivation in the aerospace industry to move away from electrical sensors, especially in the fuel system. This is driven by the need to eliminate potential ignition hazards, the desire to reduce cabling weight and the need to mitigate the effects of lightning strikes in aircraft where the conventional metallic skin is increasingly being replaced by composite materials. In this case, the authors have developed pressure sensors based on a diaphragm in which a polymer fibre Bragg grating (POFBG) has been embedded [3]. These devices provide high pressure sensitivity enabling level measurement in the mm range. Also, it has developed an approach incorporating several such sensors which can compensate for temperature drifts and is insensitive to fluid density. Compared with silica fibre-based sensors, their performance is highly enhanced. Initial results have attracted the interest of Airbus from UK, who is keen to explore the potential of optical technology in commercial aircraft. The second concerns the monitoring of acoustic signals and vibration in the subsea environment, for applications in geophysical surveying and security (detection of unwanted craft or personnel). There is strong motivation to move away from electrical sensors due to the bulk of the sensor and associated cabling and the impossibility of monitoring over large distances without electrical amplification. Optical approaches like optical hydrophones [5] offer a means of overcoming these difficulties. In collaboration with Kongsberg from Norway, the authors will exploit the sensitivity improvements possible by using POF instead of silica fibre. These improvements will arise as a result of the much more compliant nature of POF compared to silica fibre (3 GPa vs 72 GPa, respectively). Essentially, and despite the strain sensitivity of silica and POFBGs being very similar, this renders the POF much more sensitive to the applied stress resulting from acoustic signals or vibration. An alternative way of viewing this is that the POF is better impedance-matched to the surrounding environment (water for the intended applications), because although its impedance is higher than that of water, it is nearly an order of magnitude smaller than that of silica. Finally, other future industrial applications will be presented and discussed, showing the vast range of the optical fiber devices in sensing applications.

Perceptions of French and Creole Among First-Generation Adult Haitian English Language Learners

Context: Due to a unique combination of factors, outdoor athletes in the Southeastern United States are at high risk of lightning deaths and injuries. Lightning detection methods are available to minimize lightning strike victims. Objective: Becoming aware of the risk factors that predispose athletes to lightning strikes and determining the most reliable detection method against hazardous weather will enable Certified Athletic Trainers to develop protocols that protect athletes from injury. Data Sources: A comprehensive literature review of Medline and Pubmed using key words: lightning, lightning risk factors, lightning safety, lightning detection, and athletic trainers and lightning was completed. Data Synthesis: Factors predisposing athletes to lighting death or injury include: time of year, time of day, the athlete’s age, geographical location, physical location, sex, perspiration level, and lack of education and preparedness by athletes and staff. Although handheld lightning detectors have become widely accessible to detect lightning strikes, their performance has not been independently or objectively confirmed. There is evidence that these detectors inaccurately detect strike locations by recording false strikes and not recording actual strikes. Conclusions: Lightning education and preparation are two factors that can be controlled. Measures need to be taken by Certified Athletic Trainers to ensure the safety of athletes during outdoor athletics. It is critical for athletic trainers and supervising staff members to become fully aware of the risks of lightning strikes in order to most effectively protect everyone under their supervision. Even though lightning detectors have been manufactured in an attempt to minimize death and injuries due to lightning strikes, none of the detectors have been proven to be 100% effective. Educating coaches, athletes, and parents on the risks of lightning and the detection methods available, while implementing an emergency action plan for lightning safety, is crucial to ensure the well being of the student-athlete population.

Molecular detection using metallic nanowires with quantized conductance

This thesis studies the adsorption of molecules with different binding strengths onto copper nanowires with prestabilized conductance values fabricated by an electrochemical method. Since the diameters of these wires are comparable to the wavelength of conduction electrons the conductance of the nanowires is quantized, and the adsorption of even a few molecules onto atomically thin wires changes the conductance from integer values to fractional ones. These changes are proportional to the binding strength of the adsorbed molecules. The decrease in conductance is hypothesized to be caused by the scattering of the conduction electrons by the adsorbed molecules. The sensitivity of molecular adsorption-induced conductance change can be used for the development of a chemical sensor. The stabilized copper nanowires obtained in this thesis may also be used for other purposes, such as interconnecting conductors between nanodevices and digital switches in functional nanoelectronic circuitry.

A framework for investigating the use of face features to identify spontaneous emotions

Emotion-based analysis has raised a lot of interest, particularly in areas such as forensics, medicine, music, psychology, and human-machine interface. Following this trend, the use of facial analysis (either automatic or human-based) is the most common subject to be investigated once this type of data can easily be collected and is well accepted in the literature as a metric for inference of emotional states. Despite this popularity, due to several constraints found in real world scenarios (e.g. lightning, complex backgrounds, facial hair and so on), automatically obtaining affective information from face accurately is a very challenging accomplishment. This work presents a framework which aims to analyse emotional experiences through naturally generated facial expressions. Our main contribution is a new 4-dimensional model to describe emotional experiences in terms of appraisal, facial expressions, mood, and subjective experiences. In addition, we present an experiment using a new protocol proposed to obtain spontaneous emotional reactions. The results have suggested that the initial emotional state described by the participants of the experiment was different from that described after the exposure to the eliciting stimulus, thus showing that the used stimuli were capable of inducing the expected emotional states in most individuals. Moreover, our results pointed out that spontaneous facial reactions to emotions are very different from those in prototypic expressions due to the lack of expressiveness in the latter.

"Cantata para louvor e glória", de Cleide Dorta Benjamim: preparo para a execução

This study aims to document the preparation process for the implementation of "Cantata To Praise and Glory"(Cantata Para Louvor e Glória), composed in 1985 by composer Cleide Dorta Benjamin (1936 - ), in order to anticipate and address the possible difficulties faced by future conductors, singers and instrumentalists. Issues that relate to the chosen text as well as its structure and importance in the compositional process, are initially addressed through a brief presentation of the work. Consequently, by addressing every detail of the work, solutions to vocal and instrumental execution difficulties, as well as with the conducting gesture, are analyzed, identified and proposed. The work also presents a report that describes all the practical processes of preparation of the Cantata: reissue of the score; selection and profile of singers and instrumentalists; rehearsals; changes and adjustments to the score; and a brief interview with four singers and two musicians who participated in the process. The interaction with the composer throughout a significant part of the work, brings a notable increase of possible clarifications and idea development, enabling a coherent performance of the work.

O gesto regencial para além do compasso: uma discussão acerca das ferramentas da regência e de seus usos para a performance na música do século XX

This work is the result of a master’s program research developed in the post graduation program in music at the Music School of the UFRN ( Federal University of Rio Grande do Norte) under the orientation of Dr. Andre Luiz Muniz de Oliveira which aimed at making a reflexion about regency gestures and its implications about the objective and subjective elements of the performance connected to a number of regency tools concieved in accordance with the tradition of historic music. As a tool for gestual analysis we’ve used the Harold Farbermann PatternCube method. We’ve used videos from conductors Pierre Boulez e Valery Gergiev, both conducting Igor Stravinsky’s Rite of Spring. In the analysis of the videos we’ve observed the technical use of the gestual aparatus instead of the use of musical gestures fundamented in Hatten. The research showed us the importance of the use of analitical tools in helping subsidise a direction in performance in regency.