bluuebunny/crossref_metadata_2025 huggingface dataset:
Perception of peer group rank of individuals with early psychosis
Authors: Allison Gemma , Harrop Chris , Ellett Lyn
Published: July 2012

Objectives. Social rank theory has been applied to psychosis, in particular the relationship between an individual and their voices. However, perceived peer group rank has not been empirically tested in an early psychosis group. The purpose of the study was to test the prediction that individuals with early psychosis will have lower perceived social status, engage in submissive behaviours more frequently, and will feel more entrapped by external events compared to a healthy control group.

Design. The study employed a cross‐sectional design, comparing individuals with early psychosis and healthy controls.

Methods. A total of 24 participants with early psychosis and 24 matched controls completed self‐report measures of social rank, including social comparison, submissive behaviours and entrapment, measures of depression, anxiety and psychotic symptoms, and measures of peer network size and peer relationship quality.

Results. Individuals with early psychosis viewed themselves as being of lower social rank and inferior in relation to matched controls, and also reported engaging in submissive behaviours more frequently and felt more entrapped by external events.

Conclusions. Perception of lower social rank and inferiority amongst individuals with early psychosis may impact on engagement in peer relationships and impact on the social decline in early psychosis, which could have significant implications for interventions and recovery.

Practitioner Points

Individuals with early psychosis felt less satisfied with, and more excluded by, their peer group than matched controls.

Low rank in relation to peers might be a mechanism whereby individuals with early psychosis avoid their friends and lose friendships.

It may be appropriate to assess perceived social rank in relation to peers amongst individuals with early psychosis in clinical settings.

Cross‐sectional design means that no conclusions regarding causality can be made.

Peer network was assessed using self‐report and at a single time point; future longitudinal studies are therefore needed.
Multi-Modal Vibration Energy Harvesting Using a Trapezoidal Plate
Authors: Arafa Mustafa H.
Published: July 2012

Vibration-based energy harvesters are usually designed to exhibit natural frequencies that match those of the excitation for maximum power output. This has spurred interest into the design of devices that respond to variable frequency sources. In this work, an electromagnetic energy harvester in the form of a base excited trapezoidal plate is proposed. The plate geometry is designed to achieve two closely spaced vibration modes in order to harvest energy across a broader bandwidth. The ensuing bending and twisting vibrations are utilized in this capacity by placing a magnet on the plate tip that moves past a stationary coil. A dynamic model is presented to predict the system performance and is verified experimentally.
Percentiles of von Mises Stress from Combined Random Vibration and Static Loading by Approximate Noncentral Chi Square Distribution
Authors: Tibbits Patrick. A
Published: July 2012

Firstly, a calculation for percentiles of von Mises stress in linear structures subjected to Gaussian random loads is extended to the case of Gaussian random loads having nonzero mean values, i.e.,the inclusion of static loads. The development is restricted to the case of plane stress. The method includes calculation of a given percentile of von Mises stress to any desired accuracy, a rapid estimate of the percentile, and upper and lower bounds on the von Mises stress. The calculation expands the cumulative distribution function of the von Mises stress as a series of noncentral chi-square distributions. Summation of a sufficient number of terms of the series calculates the percentile to the desired accuracy. The rapid estimate of the percentile interpolates the distribution of the von Mises stress in a small number of inverse noncentral chi-square2 distribution functions. The upper and lower bounds on the percentiles take advantage of the noncentral chi-square distribution of summations of normally distributed stress components. Second and third calculation methods arise from approximations of the distribution of quadratic forms of noncentral normal variables, or equivalently, linear combinations of noncentral chi-square variables. These methods provide rapid estimates of percentiles of von Mises stress in linear structures under random loads having nonzero mean values. The accuracy and computational efficiency of the methods are reviewed and compared. The methods are expected to have wide application in design of and prognostics for components subjected to constant structural loads coupled with random loading arising from vibrations caused by wind, waves, seismic events, engines, turbulence, acoustic noise, etc.
The Response of Infinite Strings and Beams to an Initially Applied Moving Force: Analytical Solution
Authors: Langlet André , Safont Ophélie , Renard Jérôme
Published: July 2012

This paper presents the analytical solutions for bilaterally infinite strings and infinite beams on which a point force is initially applied, which then moves on the structure at a constant velocity. The solutions are sought by first applying the Fourier transform to the spatial coordinate dependence, and then the Laplace transform to the time variable of dependence, of the governing equations of motion. For the strings, it is necessary to distinguish between the case of a sonic load (a force moving at the phase velocity of transverse waves) and the cases of subsonic and supersonic loads. This is achieved by a suitable expansion in polynomial ratios of the Laplace transform, before going back to the original Fourier transform, whose inverse is obtained by exact calculations of the integrals over the complex infinite domain. For the Euler-Bernoulli beam, the same process leads to the closed-form (exact) formula for the displacement, from which the stress can be deduced. The displacement consists of the sum of two integrals: one representing the transient part, and the other, the stationary part of the solution. The stationary part is observed in the vicinity of the force for a very long travel time. The transient part is observed at a finite position coordinate, in relative proximity to the starting point of the moving force. For the Timoshenko beam, the final step in the calculation of the displacement and rotation, which requires a numerical evaluation of the integrals, leads to Fourier cosine and sine transforms. The response of the beam depends on the load velocity, relative to the two characteristic velocities: those of shear waves and longitudinal waves. This demonstrates that the transient parts of the solutions, in the Euler-Bernoulli beam or in the Timoshenko beam, are quasi identical. However, classical theory fails to forecast high frequency responses, occurring with velocities of the load exceeding twenty per cent of the bar velocity. For a velocity greater than the velocity of the shear waves, classical theory wrongly forecasts the response. In addition, according to the Euler-Bernoulli beam theory, the flexural waves are able to exceed the bar velocity, which is not realistic. If the load moves for a long period, the solution in the vicinity of the load tends towards a stationary solution. It is important to note that the solution to the stationary problem must be completed by the solution to the associated homogeneous system to represent the physical stationary solution.
A Photographic Flux Mapping Method for Concentrating Solar Collectors and Receivers
Authors: Ho Clifford K. , Khalsa Siri S.
Published: July 2012

A new method is described to determine irradiance distributions on receivers and targets from heliostats or other collectors for concentrating solar power applications. The method uses a digital camera, and, unlike previous beam characterization systems, it does not require additional sensors, calorimeters, or flux gauges on the receiver or target. In addition, spillage can exist and can also be measured (the beam does not need to be contained within the target). The only additional information required besides the images recorded from the digital camera is the direct normal irradiance and the reflectivity of the receiver. Methods are described to calculate either an average reflectivity or a reflectivity distribution for the receiver using the digital camera. The novel feature of this new photographic flux (PHLUX) mapping method is the use of recorded images of the sun to scale both the magnitude of each pixel value and the subtended angle of each pixel. A test was performed to evaluate the PHLUX method using a heliostat beam on the central receiver tower at the National Solar Thermal Test Facility in Albuquerque, NM. Results showed that the PHLUX method was capable of producing an accurate flux map of the heliostat beam on a Lambertian surface with a relative error in the peak flux of ∼2% when the filter attenuation factors and effective receiver reflectivity were well characterized. Total relative errors associated with the measured irradiance using the PHLUX method can be up to 20%–40%, depending on various error sources identified in the paper, namely, uncertainty in receiver reflectivity and filter attenuation.
The Dimensional Synthesis of Planar Parallel Cable-Driven Mechanisms Through Convex Relaxations
Authors: Azizian K. , Cardou P.
Published: July 2012

The wrench-closure workspace (WCW) of parallel cable-driven mechanisms is the set of poses for which any wrench can be produced at the end-effector by a set of positive cable tensions. In this paper, we tackle the dimensional synthesis problem, namely, that of finding a geometry for a planar parallel cable-driven mechanism (PPCDM) whose WCW contains a prescribed workspace. To this end, we first recall a linear program to determine whether a given pose is inside or outside the WCW of a given PPCDM. The relaxation of this linear program over a box leads to a nonlinear feasibility problem that can only be satisfied when this box is completely inside the WCW. We extend this feasibility problem to find a PPCDM geometry whose WCW includes a given set of boxes. These boxes represent the prescribed workspace or an estimate thereof, which may be obtained through interval analysis. Finally, we introduce a nonlinear program through which the PPCDM geometry is changed while maximizing the scaling factor of the prescribed set of boxes. When the optimum scaling factor is greater or equal to one, the WCW of the resulting PPCDM contains the set of boxes.
Experimental Investigation of Thermal Storage Processes in a Thermocline Tank
Authors: Valmiki M. M. , Karaki Wafaa , Li Peiwen , Lew Jon Van , Chan Cholik , Stephens Jake
Published: July 2012

This paper presents an experimental study of the energy charge and discharge processes in a packed bed thermocline thermal storage tank for application in concentrated solar power plants. A mathematical analysis was provided for better understanding and planning of the experimental tests. The mathematical analysis indicated that the energy storage effectiveness is related to fluid and solid material properties, tank dimensions, packing schemes of the solid filler material, and the durations of the charge and discharge times. Dimensional analysis of the governing equations was applied to consolidate many parameters into a few dimensionless parameters, allowing scaling from a laboratory system to an actual industrial application. Experiences on the system design, packing of solid filler material, system operation, and data analysis in a laboratory-scale system have been obtained in this work. These data are used to validate a recently published numerical solution method. The study will benefit the application of thermocline thermal storage systems in the large scale concentrated solar thermal power plants in industry.
Comparative Analysis of Thrust Production for Distinct Arm-Pull Styles in Competitive Swimming
Authors: Loebbecke Alfred von , Mittal Rajat
Published: July 2012

A computational fluid dynamics (CFD) based analysis of the propulsive forces generated by two distinct styles of arm-pulls in front-crawl as well as backstroke is presented in this Technical Brief. Realistic models of the arm pulling through water are created by combining underwater video footage and laser-scans of an arm with computer animation. The contributions of drag and lift forces on the arm to thrust are computed from CFD, and it is found that lift forces provide a dominant contribution to thrust for all the arm-pull styles examined. However, contrary to accepted notions in swimming, pronounced sculling (lateral motion) not only does not increase the contribution of lift forces on the hand to overall thrust, it decreases the contribution of drag forces to thrust. Consequently, pronounced sculling seems to reduce the effectiveness of the arm-pull.
Failure of Carbon Fibers at a Crease in a Fiber-Reinforced Silicone Sheet
Authors: López Jiménez Francisco , Pellegrino Sergio
Published: July 2012

Thin sheets of unidirectional carbon fibers embedded in a silicone matrix can be folded to very high curvatures, as elastic microbuckles with a half-wavelength on the order of 1 mm decrease the maximum strain in the fibers near the compression surface. This paper shows that probabilistic failure models derived from tension tests on individual fibers can be used to predict accurately the value of the outer surface curvature of the sheet, at which a small percentage of fibers break when a crease is formed in the sheet. The most accurate results are obtained by using a strain-based Weibull distribution of the failure probability in tension.
Investigation of Hydrodynamic Focusing in a Microfluidic Coulter Counter Device
Authors: Zhang Muheng , Lian Yongsheng , Harnett Cindy , Brehob Ellen
Published: July 2012

The Coulter technique enables rapid analysis of particles or cells suspended in a fluid stream. In this technique, the cells are suspended in an electrically conductive solution, which is hydrodynamically focused by nonconducting sheath flows. The cells produce a characteristic voltage signal when they interrupt an electrical path. The population and size of the cells can be obtained through analyzing the voltage signal. In a microfluidic Coulter counter device, the hydrodynamic focusing technique is used to position the conducting sample stream and the cells and also to separate close cells to generate distinct signals for each cell and avoid signal jam. The performance of hydrodynamic focusing depends on the relative flow ratio between the sample stream and sheath stream. We use a numerical approach to study the hydrodynamic focusing in a microfluidic Coulter counter device. In this approach, the flow field is described by solving the incompressible Navier-Stokes equations. The sample stream concentration is modeled by an advection-diffusion equation. The motion of the cells is governed by the Newton-Euler equations of motion. Particle motion through the flow field is handled using an overlapping grid technique. A numerical model for studying a microfluidic Coulter counter has been validated. Using the model, the impact of relative flow rate on the performance of hydrodynamic focusing was studied. Our numerical results show that the position of the sample stream can be controlled by adjusting the relative flow rate. Our simulations also show that particles can be focused into the stream and initially close particles can be separated by the hydrodynamic focusing. From our study, we conclude that hydrodynamic focusing provides an effective way to control the position of the sample stream and cells and it also can be used to separate cells to avoid signal jam.
Performance of Self-Expanding Nitinol Stent in a Curved Artery: Impact of Stent Length and Deployment Orientation
Authors: Zhao Shijia , Gu Linxia , Froemming Stacey R.
Published: July 2012

The primary aim of this work was to investigate the performance of self-expanding Nitinol stents in a curved artery through finite element analysis. The interaction between a PROTÉGÉTM GPSTM self-expanding Nitinol stent and a stenosed artery, as well as a sheath, was characterized in terms of acute lumen gain, stent underexpansion, incomplete stent apposition, and tissue prolapse. The clinical implications of these parameters were discussed. The impact of stent deployment orientation and the stent length on the arterial wall stress distribution were evaluated. It was found that the maximum principal stress increased by 17.46%, when the deployment orientation of stent was varied at a 5 deg angle. A longer stent led to an increased contact pressure between stent and underlying tissue, which might alleviate the stent migration. However, it also caused a severe hinge effect and arterial stress concentration correspondingly, which might aggravate neointimal hyperplasia. The fundamental understanding of the behavior of a self-expanding stent and its clinical implications will facilitate a better device design.
Participation of focused ion beam implanted gallium ions in metal-assisted chemical etching of silicon
Authors: Hildreth Owen , Rykaczewski Konrad , Wong Ching Ping
Published: July 2012

Metal-assisted chemical etching (MaCE) of silicon has proven to be a fast and effective method to fabricate 1D, 2D, and 3D micro- to nano-scale features in silicon. It has been shown that platinum catalysts deposited using focused ion beam (FIB) are a viable catalyst for MaCE; however, the feature fidelity of channels etched with FIB patterned catalysts are found to be significantly lower than catalysts formed using e-beam lithography. In this work we show that gallium (Ga+) ions implanted into the silicon during sample exposure result in significant etching in the irradiated regions as well as long-distance etching peripheral regions. The accelerating voltage, dose, and etching time were varied to show that the etch depth depends primarily on accelerating voltage and is largely independent of dose while the width of the peripheral region was found to scale with dose. The slope of the peripheral etching region was found to vary with both accelerating voltage and dose with three different etching times evaluated to examine how the etch profile evolves over time. These results show that Ga+ ions do participate in MaCE and care must be taken when a Ga+ ion based FIB is used.
Biaxial texture development in aluminum nitride layers during off-axis sputter deposition
Authors: Deng Ruopeng , Muralt Paul , Gall Daniel
Published: July 2012

Polycrystalline aluminum nitride (AlN) layers were deposited by pulsed-dc reactive magnetron sputtering from a variable deposition angle α = 0°–84° in 5 mTorr pure N2 at room temperature. X-ray diffraction pole figure analyses show that layers deposited from a normal angle (α = 0°) exhibit fiber texture, with a random in-plane grain orientation and the c-axis tilted by 42° ± 2° off the substrate normal, yielding wurtzite AlN grains with the {101¯2} plane approximately parallel (±2°) to the substrate surface. However, as α is increased to 45°, two preferred in-plane grain orientations emerge, with populations I and II having the c-axis tilted toward and away from the deposition flux, by 53° ± 2° and 47° ± 1° off the substrate normal, respectively. Increasing α further to 65° and 84°, results in the development of a single population II with a 43° ± 1° tilt. This developing biaxial texture is attributed to a competitive growth mode under conditions where the adatom mobility is sufficient to cause intergrain mass transport, but insufficient for the thermodynamically favored low energy {0001} planes to align parallel to the layer surface. Consequently, AlN nuclei are initially randomly oriented and form a kinetically determined crystal habit exposing {0001} and {112¯0} facets. The expected direction of its highest growth rate is 49° ± 5° tilted relative to the c-axis, in good agreement with the 42°–53° measured tilt. The in-plane preferred orientation for α > 0° is well explained by the orientation dependence in the cross section of the asymmetric pyramidal nuclei to capture directional deposition flux. The observed tilt is ideal for shear mode electromechanical coupling, which is maximized at 48°.
Bergmann Glial AMPA Receptors Are Required for Fine Motor Coordination
Authors: Saab Aiman S. , Neumeyer Alexander , Jahn Hannah M. , Cupido Alexander , Šimek Antonia A. M. , Boele Henk-Jan , Scheller Anja , Le Meur Karim , Götz Magdalena , Monyer Hannah , Sprengel Rolf , Rubio Maria E. , Deitmer Joachim W. , De Zeeuw Chris I. , Kirchhoff Frank
Published: July 2012

Crucial Cerebellar Glial Cells

The role of glial cells and their interaction with neurons in normal behavior is unclear. To address this question,

Saab
et al.

(p.
749
, published online 5 July) studied a special type of glial cell in the cerebellum. Conditional mutant mice were produced in which the two glutamate receptor subunits normally present in Bergmann glial cells were efficiently ablated in a temporally controlled manner. Glutamate signaling of the glial cells contributed to the structural and functional integrity of the cerebellar network. Bergmann glial cells also played a role in the “fine-tuning” of neuronal processing, which is crucial for the fast and precise control of complex motor behavior.
Type 6 Secretion Dynamics Within and Between Bacterial Cells
Authors: Basler M. , Mekalanos J. J.
Published: July 2012

Time-lapse video records a bacterial protein transportation machine in action.
Ethnic inequalities in incidence, survival and mortality from abdominal aortic aneurysm in New Zealand
Authors: Sandiford Peter , Mosquera Damien , Bramley Dale
Published: July 2012

Background

Ethnic variation in abdominal aortic aneurysm (AAA) incidence, survival and mortality is not well documented and yet has important equity implications for screening programmes. This study quantifies ethnic differences in hospital incidence, mortality and survival from AAA among Māori, Pacific, Asian and European/other ethnicities in New Zealand (NZ).

Methods

Retrospective analysis of linked NZ hospital and death register records identified all patients admitted to a public hospital with a diagnosis of AAA and deaths from AAA from 1996 to 2007. Patients were grouped by ethnicity as Asian, Māori, Pacific or European/other.

Results

Compared with the European/other group, Māori were 8.3 years younger at first admission, had higher mortality rates (RR=1.30, 95% CI 1.06 to 1.60 for men; RR=2.66, CI 2.13 to 3.31 for women), lower 1-year cumulative relative survival (60% vs 73% for men and 56% vs 67% for women; p<0.0001 for both) and were much less likely to have their aneurysm repaired electively (39.6% vs 61.1%; p<0.00001). Also, Māori women but not men were found to have a significantly higher standardised incidence rate (RR=1.56, 95% CI 1.37 to 1.79). In contrast, the incidence rate ratio for Asians (both men and women) was just 0.38 (95% CI 0.27 to 0.54 and 0.30 to 0.47, respectively) and both sexes also had a significantly lower mortality rate than European/other. Pacific men but not women also had a significantly lower incidence rate and frequency of aneurysm repair (40.0%; p=0.027).

Conclusions

Ethnic variation in the incidence, mortality and cumulative relative survival from AAA in NZ resembles ethnic inequalities in other health outcomes. This provides additional support for screening on equity grounds.
To nudge or not to nudge: cancer screening programmes and the limits of libertarian paternalism
Authors: Ploug Thomas , Holm Søren , Brodersen John
Published: July 2012

‘Nudging—and the underlying idea ‘libertarian paternalism’—to an increasing degree influences policy thinking in the healthcare sector. This article discusses the influence exerted upon a woman's choice of participation in the Danish breast screening programme in light of ‘libertarian paternalism’. The basic tenet of ‘libertarian paternalism’ is outlined and the relationship between ‘libertarian paternalism’ and informed consent investigated. Key elements in the process of enrolling women into the Danish mammography screening programme are introduced. It is shown that for several reasons the influence exerted upon women's choices of participation cannot be justified within a welfare-enhancing libertarian paternalistic framework. The article suggests that screening programmes alternatively adopt a liberty-enhancing approach and considers the practical implications of this alternative.
CLOSED TIMELIKE CURVES IN RELATIVISTIC COMPUTATION
Authors: ANDRÉKA HAJNAL , NÉMETI ISTVÁN , SZÉKELY GERGELY
Published: July 2012

In this paper, we investigate the possibility of using closed timelike curves (CTCs) in relativistic hypercomputation. We introduce a wormhole based hypercomputation scenario which is free of the common worries, such as the blueshift problem. We also discuss the physical reasonability of our scenario, and why we cannot simply ignore the possibility of the existence of spacetimes containing CTCs.
THE MYTH OF 'THE MYTH OF HYPERCOMPUTATION'
Authors: GOVINDARAJULU NAVEEN SUNDAR , BRINGSJORD SELMER
Published: July 2012

A myth has unfortunately arisen in connection with Martin Davis's rather aggressively titled paper "The Myth of Hypercomputation." The myth is that Davis is profoundly and decisively right therein, and that hypercomputation is indeed therefore a myth. We show herein that Davis is wrong: i.e., that it's a myth that hypercomputation is a myth. We begin by pointing out and putting to use an obvious fact about the adjective 'mythic.' (E.g., if it's a myth that ϕ (= if ϕ is mythic), where ϕ is some declarative statement, then ϕ is false.) These facts allow us to quickly prove that some of the propositions Davis can be charitably read as advancing are provably false, that some are vacuously true, and that the remainder are indeterminate. Since all that he advances falls into one of these categories, his project is an utter failure.
EMBODIED COMPUTATION: APPLYING THE PHYSICS OF COMPUTATION TO ARTIFICIAL MORPHOGENESIS
Authors: MACLENNAN BRUCE J.
Published: July 2012

We discuss the problem of assembling complex physical systems that are structured from the nanoscale up through the macroscale, and argue that embryological morphogenesis provides a good model of how this can be accomplished. Morphogenesis (whether natural or artificial) is an example of embodied computation, which exploits physical processes for computational ends, or performs computations for their physical effects. Examples of embodied computation in natural morphogenesis can be found at many levels, from allosteric proteins, which perform simple embodied computations, up through cells, which act to create tissues with specific patterns, compositions, and forms. We outline a notation for describing morphogenetic programs and illustrate its use with two examples: simple diffusion and the assembly of a simple spine with attachment points for legs. While much research remains to be done — at the simulation level before we attempt physical implementations — our results to date show how we may implement the fundamental processes of morphogenesis as a practical application of embodied computation at the nano- and microscale.
EXPLOITING THE MEMORY HIERARCHY OF MULTICORE SYSTEMS FOR PARALLEL TRIANGULATION REFINEMENT
Authors: RODRÍGUEZ PEDRO , RIVARA MARÍA CECILIA , SCHERSON ISAAC D.
Published: July 2012

A novel parallelization of the Lepp-bisection algorithm for triangulation refinement on multicore systems is presented. Randomization and wise use of the memory hierarchy are shown to highly improve algorithm performance. Given a list of selected triangles to be refined, random selection of candidates together with pre-fetching of Lepp-submeshes lead to a scalable and efficient multi-core parallel implementation. The quality of the refinement is shown to be preserved.
BLOCK-PARALLEL SYSTOLIC-ARRAY ARCHITECTURE FOR 2-D NTT-BASED FRAGILE WATERMARK EMBEDDING
Authors: ARJUNA MADANAYAKE H. L. P. , CINTRA R. J. , DIMITROV V. S. , BRUTON L. T.
Published: July 2012

Number-theoretic transforms (NTTs) have been applied in the fragile watermarking of digital images. A block-parallel systolic-array architecture is proposed for watermarking based on the 2-D special Hartley NTT (HNTT). The proposed core employs two 2-D special HNTT hardware cores, each using digital arithmetic over GF(3), and processes 4 × 4 blocks of pixels in parallel every clock cycle. Prototypes are operational on a Xilinx Sx35-10ff668 FPGA device. The maximum estimated throughput of the FPGA circuit is 100 million 4 × 4 HNTT fragile watermarked blocks per second, when clocked at 100 MHz. Potential applications exist in high-traffic back-end servers dealing with large amounts of protected digital images requiring authentication, in remote-sensing for high-security surveillance applications, in real-time video processing of information of a sensitive nature or matters of national security, in video/photographic content management of corporate clients, in authenticating multimedia for the entertainment industry, in the authentication of electronic evidence material, and in real-time news streaming.
MICROSTRUCTURE DYNAMICS AND AGENT-BASED FINANCIAL MARKETS: CAN DINOSAURS RETURN?
Authors: KAMPOURIDIS MICHAEL , CHEN SHU-HENG , TSANG EDWARD
Published: July 2012

This paper formalizes observations made under agent-based artificial stock market models into a concrete hypothesis, which is called the Dinosaur Hypothesis. This hypothesis states that the behavior of financial markets constantly changes and that the trading strategies in a market need to continuously co-evolve with it in order to remain effective. After formalizing the hypothesis, we suggest a testing methodology and run tests under 10 international financial markets. Our tests are based on a framework that we recently developed, which used Genetic Programming as a rule inference engine, and Self-Organizing Maps as a clustering machine for the above rules. However, an important assumption of that study was that maps among different periods were directly comparable with each other. In order to allow this to happen, we had to keep the same clusters throughout the different time periods of our experiments. Nevertheless, this assumption could be considered as strict or even unrealistic. In this paper, we relax this assumption. This makes our model more realistic. In addition, this allows us to investigate in depth the dynamics of market behavior and test for the plausibility of the Dinosaur Hypothesis. The results show that indeed markets' behavior constantly changes. As a consequence, strategies need to continuously co-evolve with the market; if they do not, they become obsolete or dinosaurs.
BORN'S PROPHECY LEAVES NO SPACE FOR QUANTUM GRAVITY
Authors: AMELINO-CAMELIA GIOVANNI
Published: July 2012

I stress that spacetime is a redundant abstraction, since describing the physical content of all so-called "spacetime measurements" only requires timing (by a physical/material clock) of particle detections (at a physical/material detector). It is interesting then to establish which aspects of our current theories afford us the convenient abstraction of a spacetime. I emphasize the role played by the assumed triviality of the geometry of momentum space, which makes room for an observer-independent notion of locality. This is relevant for some recent studies of the quantum-gravity problem that stumbled upon hints of a nontrivial geometry of momentum space, something which had been strikingly envisaged for quantum gravity already in 1938 by Max Born. If indeed momentum space has nontrivial geometry then the abstraction of a spacetime becomes more evidently redundant and less convenient: one may still abstract a spacetime but only allowing for the possibility of a relativity of spacetime locality. I also provide some examples of how all this could affect our attitude toward the quantum-gravity problem, including some for the program of emergent gravity and emergent spacetime. And in order to give an illustrative example of possible logical path for the "disappearance of spacetime" I rely on formulas inspired by the κ-Poincaré framework.
ATTEMPTS TO DEFINE QUASI-INTEGRABILITY
Authors: FERREIRA LUIZ A. , ZAKRZEWSKI WOJTEK J.
Published: July 2012

In this paper we discuss some ideas on how to define the concept of quasi-integrability. Our ideas stem from the observation that many field theory models are "almost" integrable; i.e. they possess a large number of "almost" conserved quantities. Most of our discussion will involve a certain class of models which generalize the sine-Gordon model in (1 + 1) dimensions. As will be mentioned many field configurations of these models look like those of the integrable systems and so appear to be close to those in integrable model. We will then attempt to quantify these claims looking in particular, both analytically and numerically, at field configurations with scattering solitons. We will also discuss some preliminary results obtained in other models.
Static and dynamic imaging of alveoli using optical coherence tomography needle probes
Authors: McLaughlin Robert A. , Yang Xiaojie , Quirk Bryden C. , Lorenser Dirk , Kirk Rodney W. , Noble Peter B. , Sampson David D.
Published: July 2012

Imaging of alveoli in situ has for the most part been infeasible due to the high resolution required to discern individual alveoli and limited access to alveoli beneath the lung surface. In this study, we present a novel technique to image alveoli using optical coherence tomography (OCT). We propose the use of OCT needle probes, where the distal imaging probe has been miniaturized and encased within a hypodermic needle (as small as 30-gauge, outer diameter 310 μm), allowing insertion deep within the lung tissue with minimal tissue distortion. Such probes enable imaging at a resolution of ∼12 μm within a three-dimensional cylindrical field of view with diameter ∼1.5 mm centered on the needle tip. The imaging technique is demonstrated on excised lungs from three different species: adult rats, fetal sheep, and adult pigs. OCT needle probes were used to image alveoli, small bronchioles, and blood vessels, and results were matched to histological sections. We also present the first dynamic OCT images acquired with an OCT needle probe, allowing tracking of individual alveoli during simulated cyclical lung inflation and deflation.
Myocardial accumulation and localization of the inducible 70-kDa heat shock protein, Hsp70, following exercise
Authors: Milne K. J. , Wolff S. , Noble E. G.
Published: July 2012

Exercise increases the 70-kDa heat shock protein (Hsp70) in the myocardium, and this exercise-induced increase is associated with significantly improved cardiac recovery following insult. However, while heat shock has been shown to elevate Hsp70 primarily in the cardiac vasculature of the myocardium, the localization following exercise is unknown. Male Sprague-Dawley rats performed continuous treadmill running at 30 m/min for 60 min (2% incline) on either 1 or 5 consecutive days. At 30 min and 24 h following exercise, hearts were extirpated, and the left ventricle was isolated, OCT-cork mounted, and sectioned for immunofluorescent analysis. Whereas immunofluorescent analysis revealed little to no Hsp70 in control hearts and 30 min postexercise, the accumulation of Hsp70 24 h after a single exercise bout or 5 days of training was predominantly located in large blood vessels and, in particular, colocalized with a marker of smooth muscle. Furthermore, higher core temperatures attained during exercise led to more abundant accumulation in smaller vessels and the endothelium. It is concluded that the accumulation of myocardial Hsp70 following acute exercise predominantly occurs in a cell type-specific manner, such that changes in the cardiac vasculature account for much of the increase. This accumulation appears first in the smooth muscle of larger vessels and then increases in smaller vessels and the endothelium, as core temperature attained during exercise increases. This finding supports the observations after heat shock and further suggests that the vasculature is a primary target in exercise-induced cardioprotection.
Ventilation-perfusion distribution in normal subjects
Authors: Beck Kenneth C. , Johnson Bruce D. , Olson Thomas P. , Wilson Theodore A.
Published: July 2012

Functional values of LogSD of the ventilation distribution (σV̇) have been reported previously, but functional values of LogSD of the perfusion distribution (σq̇) and the coefficient of correlation between ventilation and perfusion (ρ) have not been measured in humans. Here, we report values for σV̇, σq̇, and ρ obtained from wash-in data for three gases, helium and two soluble gases, acetylene and dimethyl ether. Normal subjects inspired gas containing the test gases, and the concentrations of the gases at end-expiration during the first 10 breaths were measured with the subjects at rest and at increasing levels of exercise. The regional distribution of ventilation and perfusion was described by a bivariate log-normal distribution with parameters σV̇, σq̇, and ρ, and these parameters were evaluated by matching the values of expired gas concentrations calculated for this distribution to the measured values. Values of cardiac output and LogSD ventilation/perfusion (V̇a/Q̇) were obtained. At rest, σq̇ is high (1.08 ± 0.12). With the onset of ventilation, σq̇ decreases to 0.85 ± 0.09 but remains higher than σV̇ (0.43 ± 0.09) at all exercise levels. Rho increases to 0.87 ± 0.07, and the value of LogSD V̇a/Q̇ for light and moderate exercise is primarily the result of the difference between the magnitudes of σq̇ and σV̇. With known values for the parameters, the bivariate distribution describes the comprehensive distribution of ventilation and perfusion that underlies the distribution of the V̇a/Q̇ ratio.
Dietary nitrate improves muscle but not cerebral oxygenation status during exercise in hypoxia
Authors: Masschelein Evi , Van Thienen Ruud , Wang Xu , Van Schepdael Ann , Thomis Martine , Hespel Peter
Published: July 2012

Exercise tolerance is impaired in hypoxia, and it has recently been shown that dietary nitrate supplementation can reduce the oxygen (O2) cost of muscle contractions. Therefore, we investigated the effect of dietary nitrate supplementation on arterial, muscle, and cerebral oxygenation status, symptoms of acute mountain sickness (AMS), and exercise tolerance at simulated 5,000 m altitude. Fifteen young, healthy volunteers participated in three experimental sessions according to a crossover study design. From 6 days prior to each session, subjects received either beetroot (BR) juice delivering 0.07 mmol nitrate/kg body wt/day or a control drink (CON). One session was in normoxia with CON (NORCON); the two other sessions were in hypoxia (11% O2), with either CON (HYPCON) or BR (HYPBR). Subjects first cycled for 20 min at 45% of peak O2consumption (VO2peak; EX45%) and thereafter, performed a maximal incremental exercise test (EXmax). Whole-body VO2, arterial O2saturation (%SpO2) via pulsoximetry, and tissue oxygenation index of both muscle (TOIM) and cerebral (TOIC) tissue by near-infrared spectroscopy were measured. Hypoxia per se substantially reduced VO2peak, %SpO2, TOIM, and TOIC(NORCONvs. HYPCON, P < 0.05). Compared with HYPCON, VO2at rest and during EX45%was lower in HYPBR( P < 0.05), whereas %SpO2was higher ( P < 0.05). TOIMwas ∼4-5% higher in HYPBRthan in HYPCONboth at rest and during EX45%and EXmax( P < 0.05). TOICas well as the incidence of AMS symptoms were similar between HYPCONand HYPBRat any time. Hypoxia reduced time to exhaustion in EXmaxby 36% ( P < 0.05), but this ergolytic effect was partly negated by BR (+5%, P < 0.05). Short-term dietary nitrate supplementation improves arterial and muscle oxygenation status but not cerebral oxygenation status during exercise in severe hypoxia. This is associated with improved exercise tolerance against the background of a similar incidence of AMS.
Impact of hydroxyl radical-induced injury on calcium handling and myofilament sensitivity in isolated myocardium
Authors: Haizlip Kaylan M. , Hiranandani Nitisha , Biesiadecki Brandon J. , Janssen Paul M. L.
Published: July 2012

Hydroxyl radicals (OH˙) are involved in the pathogenesis of reperfusion injury and are observed in acute heart failure, stroke, and myocardial infarction. Two different subcellular defects are involved in the pathogenesis of OH˙ injury, deranged calcium handling, and alterations of myofilament responsiveness, but their temporal impact on contractile function is not resolved. Initially, after brief OH˙ exposure, there is a corresponding marked increase in diastolic calcium and diastolic force. We followed these parameters until a new steady-state level was reached at ∼45 min post-OH˙ exposure. At this new baseline, diastolic calcium had returned to near-normal, pre-OH˙ levels, whereas diastolic force remained markedly elevated. An increased calcium sensitivity was observed at the new baseline after OH˙-induced injury compared with the pre-OH˙ state. The acute injury that occurs after OH˙ exposure is mainly due to calcium overload, while the later sustained myocardial dysfunction is mainly due to the altered/increased myofilament responsiveness.
Hand-held tools with complex kinematics are efficiently incorporated into movement planning and online control
Authors: Baugh Lee A. , Hoe Erica , Flanagan J. Randall
Published: July 2012

Certain hand-held tools alter the mapping between hand motion and motion of the tool end point that must be controlled in order to perform a task. For example, when using a pool cue, the motion of the cue tip is reversed relative to the hand. Previous studies have shown that the time required to initiate a reaching movement (Fernandez-Ruiz J, Wong W, Armstrong IT, Flanagan JR. Behav Brain Res 219: 8–14, 2011), or correct an ongoing reaching movement (Gritsenko V, Kalaska JF. J Neurophysiol 104: 3084–3104, 2010), is prolonged when the mapping between hand motion and motion of a cursor controlled by the hand is reversed. Here we show that these time costs can be significantly reduced when the reversal is instantiated by a virtual hand-held tool. Participants grasped the near end of a virtual tool, consisting of a rod connecting two circles, and moved the end point to displayed targets. In the reversal condition, the rod translated through, and rotated about, a pivot point such that there was a left-right reversal between hand and end point motion. In the nonreversal control, the tool translated with the hand. As expected, when only the two circles were presented, movement initiation and correction times were much longer in the reversal condition. However, when full vision of the tool was provided, the reaction time cost was almost eliminated. These results indicate that tools with complex kinematics can be efficiently incorporated into sensorimotor control mechanisms used in movement planning and online control.
Sensitivity to prediction error in reach adaptation
Authors: Marko Mollie K. , Haith Adrian M. , Harran Michelle D. , Shadmehr Reza
Published: July 2012

It has been proposed that the brain predicts the sensory consequences of a movement and compares it to the actual sensory feedback. When the two differ, an error signal is formed, driving adaptation. How does an error in one trial alter performance in the subsequent trial? Here we show that the sensitivity to error is not constant but declines as a function of error magnitude. That is, one learns relatively less from large errors compared with small errors. We performed an experiment in which humans made reaching movements and randomly experienced an error in both their visual and proprioceptive feedback. Proprioceptive errors were created with force fields, and visual errors were formed by perturbing the cursor trajectory to create a visual error that was smaller, the same size, or larger than the proprioceptive error. We measured single-trial adaptation and calculated sensitivity to error, i.e., the ratio of the trial-to-trial change in motor commands to error size. We found that for both sensory modalities sensitivity decreased with increasing error size. A reanalysis of a number of previously published psychophysical results also exhibited this feature. Finally, we asked how the brain might encode sensitivity to error. We reanalyzed previously published probabilities of cerebellar complex spikes (CSs) and found that this probability declined with increasing error size. From this we posit that a CS may be representative of the sensitivity to error, and not error itself, a hypothesis that may explain conflicting reports about CSs and their relationship to error.
β- And γ-band EEG power predicts illusory auditory continuity perception
Authors: Vinnik Ekaterina , Itskov Pavel M. , Balaban Evan
Published: July 2012

Because acoustic landscapes are complex and rapidly changing, auditory systems have evolved mechanisms that permit rapid detection of novel sounds, sound source segregation, and perceptual restoration of sounds obscured by noise. Perceptual restoration is particularly important in noisy environments because it allows organisms to track sounds over time even when they are masked. The continuity illusion is a striking example of perceptual restoration with sounds perceived as intact even when parts of them have been replaced by gaps and rendered inaudible by being masked by an extraneous sound. The mechanisms of auditory filling-in are complex and are currently not well-understood. The present study used the high temporal resolution of EEG to examine brain activity related to continuity illusion perception. Masking noise loudness was adjusted individually for each subject so that physically identical sounds on some trials elicited a continuity illusion (failure to detect a gap in a sound) and on other trials resulted in correct gap detection. This design ensured that any measurable differences in brain activity would be due to perceptual differences rather than physical differences among stimuli. We found that baseline activity recorded immediately before presentation of the stimulus significantly predicted the occurrence of the continuity illusion in 10 out of 14 participants based on power differences in γ-band EEG (34–80 Hz). Across all participants, power in the β and γ (12- to 80-Hz range) was informative about the subsequent perceptual decision. These data suggest that a subject's baseline brain state influences the strength of continuity illusions.