bluuebunny/crossref_metadata_2025 huggingface dataset:
Ordering of limits in the Jarzynski equality
Authors: Pressé Steve , Silbey Robert
Published: February 2006

We consider the sampling problems encountered in computing free-energy differences using Jarzynski’s nonequilibrium work relation [Phys. Rev. Lett. 56, 2690 (1997)]. This relation expresses the free-energy change of a system, on which finite-time work is done, as an average over all possible trajectories of the system. This average can then be expressed as a cumulant expansion of the work. We study the scaling of these cumulants with an appropriately defined measure of phase-space accessibility ε and particle number N for two simple changes in state. We find that the cumulant expansion is slowly convergent for predominantly entropic processes, those where ε is considerably altered during the course of the process. An accurate determination of the free-energy change requires some knowledge of the behavior of the tails of the work distribution associated with the process. Jarzynski’s irreversible work relation is only valid with the correct ordering of the infinite limits of N and ε, clarifying the regime of its applicability.
Development of magnetic Fe-based metallic glasses without metalloids
Authors: Mastrogiacomo Giovanni , Kradolfer Jürg , Löffler Jörg F.
Published: February 2006

The glass-forming ability of Fe-based metallic glasses has a direct relationship with their metalloid content. A good glass-former usually needs a metalloid content of approximately 20at.%. However, a high metalloid content causes deterioration not only in magnetic properties but also in elasticity and plasticity. Based on destabilization of the solid state we have developed a series of metalloid-free Fe-based metallic glasses of composition (Fe0.582Co0.418)100−x−yCrxZry (10⩽x⩽28 and 8⩽y⩽11). Via this destabilization the liquid state is stabilized, which results in a decreasing liquidus temperature. The mechanical and magnetic properties of the metalloid-free Fe-based metallic glass with the highest Fe and Co fractions were analyzed. The alloy of composition (Fe0.582Co0.418)80Cr10Zr10 exhibits bending elasticity and plasticity. Magnetization measurements reveal a saturation magnetization of up to 1.1T and an inverted hysteresis. The origin of this inverted hysteresis presumably lies in the inclination to decompose in a ferromagnetic iron-rich α1 phase and an antiferromagnetic chromium-rich α2 phase.
Spall behavior of aluminum with varying microstructures
Authors: Chen X. , Asay J. R. , Dwivedi S. K. , Field D. P.
Published: February 2006

A series of plate-impact spall experiments was conducted to study the spall strength of seven microstructural conditions of aluminum, including three grain sizes of 6061 Al alloy, both ultrapure and commercially pure (1060) polycrystalline aluminum, and single-crystal Al with two different orientations, over the stress range of 4–22 GPa. The pullback velocity, which is a characteristic signature of spall strength, is observed to depend on initial microstructure, impact stress, pulse duration, and loading rate. The pullback velocity generally increases over the stress range of 4–14 GPa and achieves a maximum as the impact stress approaches 22 GPa. The pullback velocity of [100] single-crystal Al is higher than that for both polycrystalline samples and [111] single-crystal samples, indicating that grain orientation strongly affects material response. Experimental results also show that the spall behavior is strongly dependent on sample thickness, while the effect of shock pulse duration was observed to be less significant. Comparison among three 6061 materials indicates that the observed differences depend on initial yield strength. The results also show that initial microstructures and impurities have a diminishing effect on the pullback velocity at stresses near 22 GPa. However, initial properties are observed to have a pronounced effect on the detailed structure of the pullback velocity profile at all stress levels. In particular, an interesting feature, i.e., a sharp slope during pullback followed by a distinct transition to a slower slope, is consistently observed. The occurrence of this change in slope is observed to depend on impact stress, loading rate, and grain size.
Comparative study of hole transport in polyspirobifluorene polymers measured by the charge-generation layer time-of-flight technique
Authors: Laquai Frédéric , Wegner Gerhard , Im Chan , Bässler Heinz , Heun Susanne
Published: February 2006

Hole transport in a polyspirobifluorene homopolymer and a statistical polyspirobifluorene-triarylamine copolymer has been studied in detail employing the charge-generation layer time-of-flight (TOF) technique over a wide range of electric fields and temperatures. Both materials exhibit nondispersive TOF signals after injection of a sheet of charge carriers from a thin (10nm) perylene-diimide charge-carrier generation layer into a relatively thick (d>1μm) polymer film. Results were analyzed within the framework of the Gaussian disorder model and the charge transport parameters were extracted for both polymers. The zero-field hole mobility of the spirohomopolymer was found to be on the order of 10−6cm2∕Vs, whereas the copolymer showed a considerably lower hole mobility of 6×10−8cm2∕Vs. The width of the density of states σ was determined to be 86meV for the homopolymer and 107meV for the copolymer. The latter polymer also showed an increased positional disorder due to the statistically incorporated triarylamine units.
One-dimensional model of valveless pumping in a closed loop and a numerical solution
Authors: Manopoulos Christos G. , Mathioulakis Demetri S. , Tsangaris Sokrates G.
Published: February 2006

The development of a theoretical model of valveless pumping and its numerical solution is presented in this work, applied for the case of a closed hydraulic loop, consisting of a soft and a rigid tube. A periodic compression and decompression of the soft tube causes a unidirectional flow, under certain conditions. The integration of the governing flow equations (continuity and momentum), over the tube cross-sectional area results in a quasi-one-dimensional unsteady model. A system of nonlinear partial differential equations of the hyperbolic type is solved numerically, employing three finite difference schemes: Lax-Wendroff, MacCormack, and Dispersion Relation Preserving, the last being the most accurate one. When the excitation takes place far from the midlength of the soft tube, a phase difference between the pressures at the two edges of each tube is developed, being in advance the one that is closer to the excitation area. Increasing the tube occlusion or the length of the excited part of the loop the mean flow rate increases and maximizes at the natural frequency of the loop. The direction of the maximum mean flow rate, for a given tube occlusion, is from the excitation area toward the edge of the stiff tube, which is located closer to the excitation area. Varying the excitation frequency both above and below the resonance frequency, local flow rate extremes appear, manifesting the complex character of the valveless pumping phenomenon.
Numerical simulation of immiscible two-phase flow in porous media
Authors: Riaz Amir , Tchelepi Hamdi A.
Published: February 2006

Nonlinear evolution of viscous and gravitational instability in two-phase immiscible displacements is analyzed with a high-accuracy numerical method. We compare our results with linear stability theory and find good agreement at small times. The fundamental physical mechanisms of finger evolution and interaction are described in terms of the competing viscous, capillary, and gravitational forces. For the parameter range considered, immiscible viscous fingers are found to undergo considerably weak interaction as compared to miscible fingers. The wave number of nonlinear fingers decreases rapidly due to the shielding mechanism and scales uniformly as t−1 at long times. We have observed that even a small amount of density contrast can eliminate viscous fingers. The dominant feature for these flows is the gravity tongue, which develops a “ridge instability” when capillary and gravity effects are of similar magnitude.
Validation of Markov state models using Shannon’s entropy
Authors: Park Sanghyun , Pande Vijay S.
Published: February 2006

Markov state models are kinetic models built from the dynamics of molecular simulation trajectories by grouping similar configurations into states and examining the transition probabilities between states. Here we present a procedure for validating the underlying Markov assumption in Markov state models based on information theory using Shannon’s entropy. This entropy method is applied to a simple system and is compared with the previous eigenvalue method. The entropy method also provides a way to identify states that are least Markovian, which can then be divided into finer states to improve the model.
Normal solutions of the Boltzmann equation for highly nonequilibrium Fourier flow and Couette flow
Authors: Gallis M. A. , Torczynski J. R. , Rader D. J. , Tij M. , Santos A.
Published: February 2006

The state of a single-species monatomic gas from near-equilibrium to highly nonequilibrium conditions is investigated using analytical and numerical methods. Normal solutions of the Boltzmann equation for Fourier flow (uniform heat flux) and Couette flow (uniform shear stress) are found in terms of the heat-flux and shear-stress Knudsen numbers. Analytical solutions are found for inverse-power-law molecules from hard sphere through Maxwell at small Knudsen numbers using Chapman-Enskog (CE) theory and for Maxwell molecules at finite Knudsen numbers using a moment-hierarchy (MH) method. Corresponding numerical solutions are obtained using the direct simulation Monte Carlo (DSMC) method of Bird. The thermal conductivity, the viscosity, and the Sonine-polynomial coefficients of the velocity distribution function from DSMC agree with CE results at small Knudsen numbers and with MH results at finite Knudsen numbers. Subtle differences between inverse-power-law, variable-soft-sphere, and variable-hard-sphere representations of Maxwell molecules are observed. The MH and DSMC results both indicate that the effective thermal conductivity and the effective viscosity for Maxwell molecules are independent of the heat-flux Knudsen number, and additional DSMC simulations indicate that these transport properties for hard-sphere molecules decrease slightly as the heat-flux Knudsen number is increased. Similarly, the MH and DSMC results indicate that the effective thermal conductivity and the effective viscosity for Maxwell molecules decrease as the shear-stress Knudsen number is increased, and additional DSMC simulations indicate the same behavior for hard-sphere molecules. These results provide strong evidence that the DSMC method can be used to determine the state of a gas under highly nonequilibrium conditions.
On Landau’s prediction for large-scale fluctuation of turbulence energy dissipation
Authors: Mouri Hideaki , Takaoka Masanori , Hori Akihiro , Kawashima Yoshihide
Published: February 2006

Kolmogorov’s theory for turbulence, proposed in 1941, is based on a hypothesis that small-scale statistics are uniquely determined by the kinematic viscosity and the mean rate of energy dissipation. Landau remarked that the local rate of energy dissipation should fluctuate in space over large scales and hence should affect small-scale statistics. Experimentally, we confirm the significance of this large-scale fluctuation, which is comparable to the mean rate of energy dissipation at the typical scale for energy-containing eddies. The significance is independent of the Reynolds number and the configuration for turbulence production. With an increase of scale r above the scale of largest energy-containing eddies, the fluctuation comes to have the scaling r−1∕2 and becomes close to Gaussian. We also confirm that the large-scale fluctuation affects small-scale statistics.
Incompressibility of the Leray-α model for wall-bounded flows
Authors: van Reeuwijk M. , Jonker H. J. J. , Hanjalić K.
Published: February 2006

This study shows that the Leray-α model does not explicitly enforce a divergence-free field for the filtered velocity. While this condition is automatically satisfied in the absence of boundaries, bounded domains require extra attention. It is shown, both analytically and through simulations of Rayleigh–Bénard convection, that incompressibility of the filtered velocity field cannot be guaranteed in the current formulation. Several suggestions are made to restore the incompressibility of the filtered velocity, and it is shown that free-slip boundary conditions for the filtered velocity do guarantee incompressibility for the domain under consideration.
Tribochemical wear of sodium trisilicate glass at the nanometer size scale
Authors: Stevens F. , Langford S. C. , Dickinson J. T.
Published: February 2006

We report measurements of single-asperity wear on sodium trisilicate glass in basic solution using atomic force microscopy (AFM), where the silicon nitride tip was used both to tribologically load and image the surface. Single-asperity micron-square polishing was performed by rastering the AFM tip in a square pattern. More localized, “nano”-machining was performed by drawing the AFM tip back and forth across the substrate in a linear fashion. In both modes, the wear rate gradually slowed during prolonged scanning. Changes in contact stress due to the wear of the AFM tip dramatically affect the observed wear rates. The changes in surface elevation for both the tip and the substrate display the same dependence on true stress and time for the case of square-raster scanning over micron dimensions. In the case of linear reciprocal scanning, conformal wear substantially modifies the rates and morphology of the wear of both the tip and the substrate.
Local control of the quantum dynamics in multiple potential wells
Authors: Marquetand Philipp , Gräfe Stefanie , Scheidel Daniel , Engel Volker
Published: February 2006

The driven wave-packet dynamics in potentials exhibiting several potential wells is investigated. Therefore, local-control strategies are employed where the control field is constructed from the system’s dynamics at any instant of time. It is shown that particles can be moved successively between various potential minima. Furthermore, results presented indicate that the intuitive local-control scheme allows for the initiation of a clockwise or counterclockwise rotational motion of a model molecular motor.
Effect of degassed elements on the degradation behavior of carbon nanotube cathodes in sealed field emission-backlight units
Authors: Lee Sora , Jeon Duk Young
Published: February 2006

The effect of degassed elements from the phosphor layer on a carbon nanotube (CNT) cathode was investigated. During the operation of field emission backlight units, it was found that zinc and sulfur were degassed from the phosphor anode. X-ray photoelectron spectroscopy analysis showed that sp2 bonding in the CNTs changed to zinc-assisted sp3-like bonding, modified by the adsorption of the zinc. The change of the CNT structure to a nonhexagonal carbon network suggests that the electron emission from the degraded CNT tips decreases due to the higher work function of sp3-like bonding, compared to that of sp2 bonding.
Combining half-metals and multiferroics into epitaxial heterostructures for spintronics
Authors: Béa H. , Bibes M. , Sirena M. , Herranz G. , Bouzehouane K. , Jacquet E. , Fusil S. , Paruch P. , Dawber M. , Contour J.-P. , Barthélémy A.
Published: February 2006

We report on the growth of epitaxial bilayers of the La2∕3Sr1∕3MnO3 (LSMO) half-metallic ferromagnet and the BiFeO3 (BFO) multiferroic, on SrTiO3(001) by pulsed laser deposition. The growth mode of both layers is two dimensional, which results in unit-cell smooth surfaces. We show that both materials keep their properties inside the heterostructures, i.e., the LSMO layer (11 nm thick) is ferromagnetic with a Curie temperature of ∼330K, while the BFO films shows ferroelectricity down to very low thicknesses (5 nm). Conductive-tip atomic force microscope mappings of BFO/LSMO bilayers for different BFO thicknesses reveal a high and homogeneous resistive state for the BFO film that can thus be used as a ferroelectric tunnel barrier in tunnel junctions based on a half-metal.
Evidence of water-related discrete trap state formation in pentacene single-crystal field-effect transistors
Authors: Goldmann C. , Gundlach D. J. , Batlogg B.
Published: February 2006

We report on the generation of a discrete trap state during negative gate bias stress in pentacene single-crystal “flip-crystal” field-effect transistors with a SiO2 gate dielectric. Trap densities of up to 2∙1012cm−2 were created in the experiments. Trap formation and trap relaxation are distinctly different above and below ∼280K. In devices in which a self-assembled monolayer on top of the SiO2 provides a hydrophobic insulator surface we do not observe trap formation. These results indicate the microscopic cause of the trap state to be related to molecular layers of water adsorbed on the SiO2 surface.
Room temperature slow and fast light in quantum-dot semiconductor optical amplifiers
Authors: Su Hui , Chuang Shun Lien
Published: February 2006

We demonstrate room temperature optically and electrically controllable group delay using population oscillation in a quantum-dot (QD) semiconductor optical amplifier (SOA). A reduction of the group index up to 10% with a bandwidth of 13 GHz is achieved under different configurations of injection current and optical pump intensity. Our theoretical results based on population pulsation agree well with experimental data. We extract the linewidth enhancement factor and effective carrier diffusion coefficient of the QD SOA. We also observe slow light when the injection current is increased.
Functionalization of carbon nanotubes with proteins and quantum dots in aqueous buffer solutions
Authors: Prakash R. , Superfine Rich , Washburn S. , Falvo Michael R.
Published: February 2006

We report here on a method of suspending carbon nanotubes (CNTs) in aqueous buffer solutions and functionalizing CNTs with a molecule that is “sticky” to proteins. The specific bifunctional molecule used in this study is 1-pyrene butanoic acid succidymidyl ester (1-pbase). We report successful protein and quantum dot functionalization of the CNTs, using 1-pbase as a linking agent.
Studies of charge carrier trapping and recombination processes in Si∕SiO2∕MgO structures using second-harmonic generation
Authors: White Y. V. , Lu X. , Pasternak R. , Tolk N. H. , Chatterjee A. , Schrimpf R. D. , Fleetwood D. M. , Ueda A. , Mu R.
Published: February 2006

Effects of MgO deposition on Si∕SiO2 system and charge carrier trapping and recombination in Si∕SiO2∕MgO structures are studied using second-harmonic generation (SHG). An ultrafast 800nm laser was used both for multi-photon induced electron injection through the SiO2 into a potential well in the MgO, and for monitoring the time-dependent SHG signal, which is sensitive to the electric field at the Si∕SiO2 interface. Our results indicate that the MgO deposition introduces new trap states, and electrons trapped in the MgO transport more readily through the SiO2 than those in traps on the surface of SiO2. We attribute this to differences in trap energy levels and/or differences in process damage-induced defect densities in the SiO2.
Propagation of stacking faults from surface damage in SiC PiN diodes
Authors: Zhang Z. , Maximenko S. I. , Shrivastava A. , Sadagopan P. , Gao Y. , Sudarshan T. S.
Published: February 2006

The propagation of stacking faults (SF) in SiC PiN diodes under forward bias was studied by the electron beam induced current mode of scanning electron microscopy. The primary SF nucleation sites were confirmed to be pre-existing basal plane dislocations (BPD). Damage to the diode surface can also cause SF propagation in the device. Hence, in addition to the elimination of BPDs in the active layer of the diode, avoidance of surface damage by paying careful attention to device processing and testing is also important for fabricating stable SiC PiN diodes.
Electrical modulation of silicon-based two-dimensional photonic bandgap structures
Authors: Haurylau M. , Anderson S. P. , Marshall K. L. , Fauchet P. M.
Published: February 2006

Electrically tunable photonic band gap (PBG) structures hold the potential to become a versatile and compact backbone for optical signal processing. In this letter we report electrical tuning of silicon-based two-dimensional PBG structures infiltrated with liquid crystals. An improved electrode configuration is used to avoid electric field screening by the conductive silicon walls. Electrical tuning using fields well below 1V∕μm is demonstrated experimentally using both polarized light microscopy and reflectance PBG measurements. The structures can be operated with any electro-optic materials and lead to fast and efficient modulators, routers, and tunable filters.
Efficient 3-μm difference frequency generation using direct-bonded quasi-phase-matched LiNbO3 ridge waveguides
Authors: Tadanaga Osamu , Yanagawa Tsutomu , Nishida Yoshiki , Miyazawa Hiroshi , Magari Katsuaki , Asobe Masaki , Suzuki Hiroyuki
Published: February 2006

We fabricate 50-mm-long direct-bonded quasi-phase-matched LiNbO3 ridge waveguides for difference frequency generation in the 3-μm wavelength range. Conversion efficiency of 40%/W is achieved using a 1-μm-band pump and a 1.55-μm-band signal, and a 0.26-mW output is obtained. We also use the device to demonstrate methane gas detection at around 3.3μm.
Exciton localization in AlGaN alloys
Authors: Nepal N. , Li J. , Nakarmi M. L. , Lin J. Y. , Jiang H. X.
Published: February 2006

Deep ultraviolet (UV) photoluminescence emission spectroscopy has been employed to study the exciton localization effect in AlGaN alloys. The temperature dependence of the exciton emission peak energy in AlxGa1−xN alloys (0⩽x⩽1) was measured from 10to800K and fitted by the Varshni equation. Deviations of the measured data from the Varshni equation at low temperatures directly provide the exciton localization energies, ELoc. It was found that ELoc increases with x for x⩽0.7, and decreases with x for x⩾0.8. Our experimental results revealed that for AlGaN alloys, ELoc obtained by the above method has simple linear relations with the localized exciton thermal activation energy and the emission linewidth, thereby established three parallel methods for directly measuring the exciton localization energies in AlGaN alloys. The consequence of strong carrier and exciton localization in AlGaN alloys on the applications of nitride deep UV optoelectronic devices is also discussed.
Improved performance in Ru∕Ta2O5∕Ru capacitors using forming gas annealing
Authors: Lin Jun , Suzuki Toshiya , Matsunaga Daisuke , Eguchi Kazuhiro
Published: February 2006

The effects of forming gas (H2∕N2=3%∕97%) annealing (FGA) on Ru∕Ta2O5∕Ru capacitors are studied. It is confirmed that the effects of FGA highly depend on its timing in the preparation sequence. Though FGA after the patterning of the Ru top electrode results in the increased leakage current of the capacitor, FGA prior to the patterning of the Ru top electrode substantially reduces the leakage current and prevents subsequent thermal process-induced peeling between Ta2O5 and Ru, yielding the capacitor with the best electrical characteristics. Such improvements most likely originate from the formation of a stable bonded interface intrinsically linked to Ta2O5 and Ru, and the phase change from TaOx to Ta2O5.
Marketing the Eikaiwa Wonderland: Ideology, Akogare, and Gender Alterity in English Conversation School Advertising in Japan
Authors: Bailey Keiron
Published: February 2006

The English conversation school ( eikaiwa) industry in Japan has grown significantly over the past twenty-five years. In this paper I perform a semiological analysis on a set of eikaiwa promotional materials gathered in Tokyo and Kanagawa during the period 1998–2002. This analysis relies on a framework of social modalities (Rose, 2001 Visual Methodologies Sage, London) within which a set of gendered Occidentalized longings ( akogare) is discussed. Career development, establishment of relationships with white males, and the potentials for foreign travel and study are highlighted by these eikaiwa promotions. These factors are presented as radical gender alterities that work against the social modalities encountered in Japan. These modalities include a set of rigid life-course expectations and a mode of social regulation that strongly directs women's professional and personal development. While English-language learning and use contain potentials for epistemological challenge to ideologies of gender, the eikaiwa visually emphasize the development of new selfhood ( atarashii jibun). In these promotions key signification is performed by white-male and Japanese-female pairings. According to Kelsky (2001 Women on the Verge Duke University Press, Durham, NC), the white male is represented as an agent of personal transformation and liberation associated with the development of new selfhood. The white male embodies an Occidentalist fantasy that is associated with personal freedom, career development, and individuation. Simultaneously, the promotions articulate with the valorization of female agency in the broader Japanese cultural sphere, and with what Kelsky (1999, page 238) terms “emergent erotic discourses of new selfhood”. Where women are featured, in contrast to Western promotional materials, their purpose is to appeal to other women. This is accomplished by presenting famous women in professionally iconic settings. When they do appear, Japanese males are infantalized and marginalized. The eikaiwa are therefore marketed as wonderlands, rich with radical gender alterities, within which the akogare of female students can be realized.
Reontologising Race: The Machinic Geography of Phenotype
Authors: Saldanha Arun
Published: February 2006

In contradistinction to the treatment of race as a problem of epistomology—how is phenotype represented in racial discourse—the author seeks to defend a materialist ontology of race. The creative materiality of race is asserted following the ‘material turn’ in feminism, anthropology, complexity theory, and Deleuze. Race is shown to be an embodied and material event, a ‘machine assemblage’ with a different spatiality than the self/other scheme of Hegel. Taking issue with the calls for the transcendence of race amongst cultural studies scholars such as Paul Gilroy, the author ends the paper by suggesting that the political battle against racial subordination includes a serious engagement with its biological dimensions. Race should not be eliminated, but its energies harnessed through a cosmopolitan ethics which is sensitive to its heterogeneous and dynamic nature.
Public Relations, Private Security: Managing Youth and Race at the Mall of America
Authors: O'Dougherty Maureen
Published: February 2006

In this paper, I examine the weekend night curfew imposed on youth under 16 years of age at the Mall of America (MOA). The discussion is based on qualitative research including twenty-six weekend observations of the curfew enforcement, interviews with security of color subcontracted by mall management to enforce the curfew, and media analysis of public relations efforts concerning disturbances and lawsuits involving security guards and youth of color at the mall. I argue that MOA security measures are closely linked with public relations (PR) and that a central function of PR as a support for security is to veil the racial dynamics motivating management policies at the mall. Key illustrations of the PR–security links and aims are seen in the campaign to ‘sell’ the curfew, which displaced issues of racial and generational inequalities onto moralizing discourses of property, safety, and family values, and in the deployment of security of color to accomplish friendly exclusions and managed inclusions of youth.
Aesthetic Phenomena as Supernormal Stimuli: The Case of Eye, Lip, and Lower-Face Size and Roundness in Artistic Portraits
Authors: Costa Marco , Corazza Leonardo
Published: February 2006

In the first study, eye and lip size and roundness, and lower-face roundness were compared between a control sample of 289 photographic portraits and an experimental sample of 776 artistic portraits covering the whole period of the history of art. Results showed that eye roundness, lip roundness, eye height, eye width, and lip height were significantly enhanced in artistic portraits compared to photographic ones. Lip width and lower-face roundness, on the contrary, were less prominent in artistic than in photographic portraits. In a second study, forty-two art academy students were requested to draw two self-portraits, one with a mirror and one without (from memory). Eye, lip, and lower-face roundness in artistic self-portraits was compared to the same features derived from photographic portraits of the participants. The results obtained confirmed those found in the first study. Eye and lip size and roundness were greater in artistic self-portraits, while lower-face roundness was significantly reduced. The same degree of modification was found also when a mirror was available to the subjects. In a third study the effect of lower-face roundness on the perception of attractiveness was assessed: fifty-three participants had to adjust the face width of 24 photographic portraits in order to achieve the highest level of attractiveness. Participants contracted the face width by a mean value of 5.26%, showing a preference for a reduced lower-face roundness. All results are discussed in terms of the importance of the ‘supernormalisation’ process as a means of assigning aesthetic value to perceptual stimuli.
Disparity and Shading Cues Cooperate for Surface Interpolation
Authors: Vuong Quoc C , Domini Fulvio , Caudek Corrado
Published: February 2006

In two experiments, we tested whether disparity and shading cues cooperated for surface interpolation. Observers adjusted a probe dot to lie on a surface specified either by a sparse disparity field, a continuous stereo shading or monocular shading gradient, or both cues. Observers' adjustments were very consistent with disparity information but their adjustments were much more variable with shading information. However, observers significantly improved their precision when both cues were present, relative to when only disparity information was present. These results cannot be explained by assuming that separate modules analyze disparity and shading information, even if observers optimally combined these cues. Rather, we attribute this improvement to a process through which the shading gradient constrains the disparity field in regions where disparities cannot be directly measured. This cooperative process may be based on the natural covariation existing between these cues produced by the retinal projection of smooth surfaces.
The Perception of Tempo in Music
Authors: Quinn Sandra , Watt Roger
Published: February 2006

Tempo is one factor that is frequently associated with the expressive nature of a piece of music. Composers often indicate the tempo of a piece of music through the use of numerical markings (beats min−1) and subjective terms (adagio, allegro). Three studies were conducted to assess whether listeners were able to make consistent judgments about tempo that varied from piece to piece. Listeners heard short extracts of Scottish music played at a range of tempi and were asked to make a two-alternative forced choice of “too fast” or “too slow” for each extract. The responses for each study were plotted as proportion of too fast responses as a function of tempo for each piece, and cumulative normal curves were fitted to each data set. The point where these curves cross 0.5 is the tempo at which the music sounds right to the listeners, referred to as the optimal tempo. The results from each study show that listeners are capable of making consistent tempo judgments and that the optimal tempo varies across extracts. The results also revealed that rhythm plays a role, but not the only role in making temporal judgments.
Testing the Tilt-Constancy Theory of Visual Illusions
Authors: Wenderoth Peter , Burke Darren
Published: February 2006

Prinzmetal and Beck (2001) Journal of Experimental Psychology: Human Perception and Performance27 206–217) argued that a subset of visual illusions is caused by the same mechanisms that are responsible for the perception of vertical and horizontal—a theory they referred to as the tilt-constancy theory of visual illusions. They argued that these illusions should increase if the observer's head or head and body are tilted because extra reliance would then be placed on the illusion-inducing local visual context. Exactly that result had previously been reported in the case of the tilted-room and the rod-and-frame illusions. Prinzmetal and Beck reported similar increases in the tilt illusion (TI), as well as the Zöllner, Poggendorff, and Ponzo illusions. In two experiments, we re-examined the effect of head tilt on the TI. In experiment 1, we used more conventional TI stimuli, more standard experimental methods, and a more complete experimental design than Prinzmetal and Beck, and additionally extended the investigation to attraction as well as repulsion effects. Experiment 2 more closely replicated the Prinzmetal and Beck stimuli. Although we found that head tilt did increase TIs in both experiments, the increases were of the order of 1°–2°, more modest than the 7° reported by Prinzmetal and Beck. Significantly, the TI increase was larger when inducing tilts and head tilts were in the same direction than when they were in opposite directions, suggesting that the tilt-constancy theory may be oversimplified. In addition, because previous evidence renders unlikely the claim that the Poggendorff illusion can be explained simply in terms of misperceived orientation of the transversals, the question arises whether there might be some other explanation for the increase in the Zöllner, Poggendorff, and Ponzo illusions with body tilt that Prinzmetal and Beck reported.
Molecular cloning and assessment of the immunocontraceptive potential of the zona pellucida subunit 3 from Brandt's vole (Microtus brandti)
Authors: Li Hui , Piao Yun-shang , Zhang Zhi-bin , Hardy Christopher M. , Hinds Lyn A.
Published: February 2006

A full-length cDNA encoding Brandt’s vole (Microtus brandti) zona pellucida glycoprotein subunit 3 (vZP3) was isolated using rapid amplification of cDNA ends–polymerase chain reaction (RACE-PCR). The cDNA contains an open reading frame of 1254 nucleotides encoding a polypeptide of 418 amino acid residues. The deduced amino acid sequence of vZP3 revealed high overall homology with hamster (82.1%), mouse (81.3%) and rat (80.6%). A synthetic vZP3 peptide corresponding to amino acid residues 328–343 was conjugated to keyhole limpet hemocyanin (KLH-vZP3328–343) and used to immunise female Brandt’s voles in order to test the efficacy of this peptide as a contraceptive antigen. High IgG antibody levels to the vZP3328–343 peptide were present in the sera of female voles immunised with KLH-vZP3328–343 and these also cross-reacted to the zona pellucida in ovaries of Brandt’s vole. The fertility of the KLH-vZP3328–343-immunised voles was reduced by 50% compared with controls without evidence of significant ovarian pathology.
Development of sperm sexing and associated assisted reproductive technology for sex preselection of captive bottlenose dolphins (Tursiops truncatus)
Authors: O'Brien J. K. , Robeck T. R.
Published: February 2006

Research was conducted to develop sperm sorting and novel sperm preservation methodologies for sex predetermination in the bottlenose dolphin (Tursiops truncatus) using artificial insemination. In Study 1, the effect of seminal plasma (SP), sperm concentration and freezing rate (FR) on in vitro sperm quality of liquid-stored, non-sorted spermatozoa was examined. There was no effect (P > 0.05) of prefreeze SP addition on post-thaw quality (progressive motility, kinetic rating, sperm motility index (SMI), viability and acrosome integrity). Post-thaw motility parameters and viability were higher (P < 0.05) for slow FR than fast FR samples. In Study 2 investigating the effects of liquid storage and sorting on sperm quality, motility and SMI after sorting and centrifugation were lower (P < 0.05) than those of the initial ejaculate. The sort rate for enrichment (91 ± 4% purity) of X- and Y-bearing spermatozoa was 3400 ± 850 spermatozoa sex−1 s−1. In Study 3, compared with a modified straw method, directional freezing resulted in enhanced in vitro quality of sorted and non-sorted spermatozoa derived from liquid-stored semen (P < 0.05). In Study 4, endoscopic insemination of three dolphins with sorted, frozen–thawed X-bearing spermatozoa resulted in one conception and the birth of a female calf. High-purity sorting of dolphin spermatozoa, derived from liquid-stored semen, can be achieved with minimal loss of in vitro sperm quality and samples are functional in vivo.
Assessment of sperm quality parameters of six bulls showing different abilities to promote embryo development in vitro
Authors: Alomar M. , Mahieu J. , Verhaeghe B. , Defoin L. , Donnay I.
Published: February 2006

Experiments were conducted to investigate the possible origins of variation between six bulls showing various blastocyst rates after in vitro fertilisation. No significant difference was observed for the rates of cleavage and 5–8 cell stages, whereas blastocyst yields at Day 6, 7 and 8 post insemination were significantly different between bulls (P < 0.05). Fertilisation rates ranged from 59.5 to 79.3% (P < 0.05), with no difference in the incidence of polyspermy. The proportions of motile and progressive spermatozoa before and after Percoll separation were analysed. A positive effect of Percoll was noted on both parameters (P < 0.05), leading to the absence of difference between bulls after the separation process. Sperm viability and spontaneous acrosome reaction were assessed during 18 h incubation in fertilisation medium. A sharp decrease in sperm viability was observed for all bulls after 2 h incubation, with only 12.6–21.7% of spermatozoa still viable at 18 h. In contrast, the proportion of reacted acrosomes was low in five out of six bulls (<15% at 18 h). In conclusion, the fertilisation rate was the only parameter to show some correlation with blastocyst rate for all bulls.
Nutritional restriction in lactating primiparous sows selectively affects female embryo survival and overall litter development
Authors: Vinsky M. D. , Novak S. , Dixon W. T. , Dyck M. K. , Foxcroft G. R.
Published: February 2006

This study explored the possibility of sex-specific effects on embryonic survival in primiparous sows subjected to restricted feed intake during the last week of lactation and bred after weaning (Restrict; n = 16), compared with control sows fed close to ad libitum feed intakes (Control; n = 17). Restrict sows were in a substantial negative net energy balance at weaning, and lost 13% of estimated protein and 17% of fat mass during lactation, yet the weaning-to-oestrous interval and ovulation rate were not different between treatments. However, embryonic survival at Day 30 of gestation was lower (P < 0.05) in Restrict than Control sows, and selectively reduced the proportion of female embryos surviving (P < 0.01). A decrease in weight and crown–rump length of surviving female (P < 0.05) and male (P < 0.05) embryos was seen in Restrict litters. The mechanisms mediating this sex-specific effect on embryonic loss in feed-restricted sows are unclear. The data presented here indicate that feed-restriction during the last week of lactation in primiparous sows causes a selective decrease in survival of female embryos and limits the growth of all surviving embryos.
The Kadison–Singer Problem in mathematics and engineering
Authors: Casazza Peter G. , Tremain Janet Crandell
Published: February 2006

We will see that the famous intractible 1959 Kadison–Singer Problem in
C
*-algebras is equivalent to fundamental open problems in a dozen different areas of research in mathematics and engineering. This work gives all these areas common ground on which to interact as well as explaining why each area has volumes of literature on their respective problems without a satisfactory resolution.
Anthrax lethal factor and edema factor act on conserved targets in
Drosophila
Authors: Guichard Annabel , Park Jin Mo , Cruz-Moreno Beatriz , Karin Michael , Bier Ethan
Published: February 2006

Many bacterial toxins act on conserved components of essential host-signaling pathways. One consequence of this conservation is that genetic model organisms such as
Drosophila melanogaster
can be used for analyzing the mechanism of toxin action. In this study, we characterize the activities of two anthrax virulence factors, lethal factor (LF) and edema factor, in transgenic
Drosophila
. LF is a zinc metalloprotease that cleaves and inactivates most human mitogen-activated protein kinase (MAPK) kinases (MAPKKs). We found that LF similarly cleaves the
Drosophila
MAPK kinases Hemipterous (Hep) and Licorne
in vitro
. Consistent with these observations, expression of LF in
Drosophila
inhibited the Hep/c-Jun N-terminal kinase pathway during embryonic dorsal closure and the related process of adult thoracic closure. Epistasis experiments confirmed that LF acts at the level of Hep. We also found that LF inhibits Ras/MAPK signaling during wing development and that LF acts upstream of MAPK and downstream of Raf, consistent with LF acting at the level of Dsor. In addition, we found that edema factor, a potent adenylate cyclase, inhibits the
hh
pathway during wing development, consistent with the known role of cAMP-dependent PKA in suppressing the Hedgehog response. These results demonstrate that anthrax toxins function in
Drosophila
as they do in mammalian cells and open the way to using
Drosophila
as a multicellular host system for studying the
in vivo
function of diverse toxins and virulence factors.
Unique, common, and interacting cortical correlates of thirst and pain
Authors: Farrell Michael J. , Egan Gary F. , Zamarripa Frank , Shade Robert , Blair-West John , Fox Peter , Denton Derek A.
Published: February 2006

This study used positron-emission tomography to establish the patterns of brain activity involved in the isolated and concurrent experiences of thirst and pain. Ten subjects were scanned while experiencing pain evoked with noxious pressure, while experiencing thirst after the infusion of hypertonic saline, and while experiencing pain when thirsty. After the onset of thirst, noxious pressure evoked more intense sensations of pain. Noxious pressure did not change subjective ratings of thirst. Thirst caused activation in the anterior cingulate (Brodmann area 32) and the insula. Enhanced pain responses were associated with increased activity in cortical regions that are known to correlate with pain intensity, and also with unique activity in the pregenual anterior cingulate and ventral orbitofrontal cortex. These findings suggest a role for limbic and prefrontal cortices in the modulation of pain during the experience of thirst.
Molecular Epidemiology of Vancomycin-Resistant Enterococci: A 2-Year Perspective
Authors: Stosor Valentina , Kruszynski Julie , Suriano Terra , Noskin Gary A. , Peterson Lance R.
Published: February 2006

Objective:

To determine the molecular epidemiology of vancomycin-resistant enterococci (VRE) at our medical center in order to identify the extent of strain clonality and possible transmission patterns of this pathogen.

Design:

An important facet of our infection control program includes molecular typing of all clinical and surveillance isolates of VRE to determine transmission patterns in the hospital. Molecular strain typing is performed by restriction endonuclease analysis (REA) of genomic DNA. REA patterns are visually compared to categorize VRE strains into type and subtype designations.

Setting:

A 588-bed, university-affiliated, tertiary-care hospital and a neighboring 155-bed rehabilitation facility.

Results:

From January 1995 through December 1996, 379 VRE isolates were collected from 197 patients. Thirty-three genotypes were determined by REA typing; 15 genotypes were implicated in 29 instances of potential nosocomial transmission. Three major clusters of VRE involving patients on multiple nursing units and two adjacent hospitals were identified. The remaining instances of nosocomial transmission occurred in small patient clusters.

Conclusions:

In conclusion, the VRE epidemic at this medical center is polyclonal. VRE transmission patterns are complex, and, while large clusters do occur, the usual pattern of nosocomial acquisition of this pathogen occurs in the setting of “mini-clusters”.
Requirements for Infrastructure and Essential Activities of Infection Control and Epidemiology in Out-of-Hospital Settings: A Consensus Panel Report
Authors: Friedman Candace , Barnette Marcie , Buck Alfred S. , Ham Rosemary , Harris Jo-Ann , Hoffman Peggy , Johnson Debra , Manian Farrin , Nicolle Lindsay , Pearson Michele L. , Perl Trish M. , Solomon Steven L.
Published: February 2006

In 1997 the Association for Professionals in Infection Control and Epidemiology and the Society for Healthcare Epidemiology of America established a consensus panel to develop recommendations for optimal infrastructure and essential activities of infection control and epidemiology programs in out-of-hospital settings. The following report represents the Consensus Panel's best assessment of requirements for a healthy and effective out-of-hospital-based infection control and epidemiology program. The recommendations fall into 5 categories: managing critical data and information; developing and recommending policies and procedures; intervening directly to prevent infections; educating and training of health care workers, patients, and nonmedical caregivers; and resources. The Consensus Panel used an evidence-based approach and categorized recommendations according to modifications of the scheme developed by the Clinical Affairs Committee of the Infectious Diseases Society of America and the Centers for Disease Control and Prevention's Healthcare Infection Control Practices Advisory Committee.