bluuebunny/crossref_metadata_2025 huggingface dataset:
Spray and Cooling Dynamics of Cryogen Sprays Impinging on a Human Skin Model
Authors: Franco Walfre , Vu Henry , Jia Wangcun , Nelson J. Stuart , Aguilar Guillermo
Published: April 2009

The objective of the present work is to correlate the time-dependent flow characteristics of cryogen sprays to the induced thermal dynamics at the surface of a human skin model. First, a numerical analysis to evaluate our skin model is carried out. Next, diameter and axial velocity of droplets impinging onto the skin model are measured. Diameter, velocity and surface temperature are acquired simultaneously at the center of the spray cone close to and at the skin model surface, respectively. Spurt durations of 10, 30 and 50 ms are investigated. Finally, measurements are used to compute spray number, mass and kinetic energy fluxes and surface heat flux. Numerical modeling shows that, subject to the same heat flux, the thermal response of our model and human skin is qualitatively similar but the total temperature drop in skin is about 50% less than that of the model. A simple transformation can be used to map the temperature response of the model to that of skin. Experimental measurements show that during the initial spray transient, fast and small droplets (respect to steady state values) induce large temperature drops and the highest heat flux because the temperature difference between liquid and substrate is the largest; during the spray steady state, surface temperature remains at its lowest value; during the final transient, droplets are fast and small again, although their impact on the surface heat transfer is negligible due to decreasing mass and kinetic energy fluxes and reduced temperature differences between liquid and substrate.
Transport in Superhydrophobic Microchannels: A Porous Modeling Approach
Authors: Enright Ryan , Eason Cormac , Dalton Tara , Salamon Todd
Published: April 2009

Superhydrophobic surfaces combine roughness features with low energy surfaces to create materials with substantially decreased wettability and reduced drag resistance in laminar flows. These characteristics make superhydrophobic surfaces a promising technology for reducing the flow resistance of microchannels in a variety of applications, including thermal management and biofluidics. The presence of a gas layer that is trapped within the superhydrophobic surface, and which separates the majority of the microchannel wall from the working fluid, gives rise to a low shear-stress region responsible for the observed reduction in flow resistance. Although there have been numerous experimental and computational studies of fluid flow in superhydrophobic microchannels, to our knowledge no predictive analytical model capturing the essential features of the flow has been developed for the case of post-type surface roughness. In this work we propose the use of porous flow theory to predict the behavior of the fully-developed inertia-less flow of a constant viscosity Newtonian fluid in a parallel-plate, super-hydrophobic microchannel whose roughness features are composed of a square array of posts arranged transverse to the flow. The volume-averaged Navier-Stokes (VANS) equation is used to model the flow behavior in both the open and porous regions, taking into account the presence of a recirculating gas layer and the potential for partial liquid penetration into the porous region. The fluid motion in the porous and non-porous regions is coupled by imposing boundary conditions specifying the continuity of velocity and a stress jump at the interface between the two regions. An empirical factor, known as the stress jump coefficient β, appears in the stress jump boundary condition and is shown to be correlated to the geometric properties of the porous region via a scaling law inferred from non-dimensional analysis and observed in 3D computational fluid dynamics simulations. Finally, the predictions of the model are compared with existing experimental studies.
Experimental Study of Turbulent Local Enhanced Heat Transfer in Wavy-Wall Channel
Authors: Couton D. , Hoang-Hong M. , Robert J. , Tuhault J. L. , Doan-Kim S.
Published: April 2009

The aim of this study is to analyze the phenomena of heat transfer enhancement between two periodic sinusoidal walls for a single gas flow. The experimental set-up is characterized by a few geometrical parameters: amplitude of wall waviness (A); channel height (H); fin wavy-channel width (ω); fin period (l) and total wavy length (L). Combination of these ones is reduced to: the wall aspect ratio γ, the cross-section aspect ratio α and the channel spacing ratio ε. The Reynolds number defined on the hydraulic diameter and the bulk velocity is greater than 4000. A constant heat flux is maintained on the second lateral wall. For Re = 5700, we observe an entrance region from the first to the fourth period; beyond, the velocity profiles are autosimilar. A shear layer is generated just downstream of the crest and develops in its wake up to the concavity area. Thermal experimental approach is performed by local measurements of convective heat transfer coefficient along the walls, within the viscous sublayer. The heat transfer profile presents an increasing from the crest of 15%, and the maximum is located at the first quarter of the period, close to the separated point. Beyond, the value of heat transfer decreases of 50% and the minimum is located close to the reattachment point. Then the heat transfer increases up to the next crest. The same phenomenon is observed in the next periods of the channel. To explain theses results, we calculate the turbulence terms obtained from the classical equations of fluid mechanics. The turbulence production (P) presents a maximum in the core of the shear layer, where the Reynolds constraints and the heat transfer are maxima. A good correlation is obtained between turbulence production and heat transfer. The flow pattern (mean, fluctuating and turbulence terms) are performed with PIV technique in order to analyze the vortices that develop in the shear layer, based on 1000 pairs of images.
Experimental Investigation of the CHF Condition During Flow Boiling of Water in Microtubes
Authors: Roday Anand P. , Jensen Michael K.
Published: April 2009

The critical heat flux (CHF) condition sets an upper limit on the flow-boiling heat transfer process. With the growing demand for the use of two-phase flow in micro and nano-sized devices, there is a strong need to understand the CHF phenomenon in channels of such small dimensions. This study experimentally investigates the critical heat flux condition during flow boiling in a single stainless steel microtube of two different diameters—0.427mm, and 0.286 mm. Degassed water is the working fluid. The effects of various parameters—diameter, mass flux (350–1500 kg/m2s), inlet subcooling (2°C–50°C), and length-to-diameter ratio (75–200) on the CHF condition are studied for the exit condition being nearly atmospheric pressure. The CHF increases with an increase in mass flux. The effect of the inlet subcooling on the CHF condition is more complex. With a decreasing inlet subcooling, the CHF decreases until saturated liquid is reached; thereafter, the CHF increases with quality.
In-Plane Thermal and Thermoelectric Properties of Polycrystalline Highly Preferred Orientation [(W)x(WSE2)y]z Superlattice Thin Films
Authors: Mavrokefalos Anastassios , Nguyen Ngoc T. , Pettes Michael T. , Johnson David C. , Shi Li
Published: April 2009

It was recently found by using the time domain thermal reflectance method that polycrystalline highly preferred orientation WSe2 and [(W)x(WSe2)y]z superlattice films possess extremely low cross-plane thermal conductivity, which is desirable for thermal insulation and thermoelectric energy conversion applications. However, it is difficult to obtain the in-plane thermal conductivity by using the laser reflectance or the 3-ω method. Here we employ a suspended microdevice developed for measuring thermoelectric properties of individual nanowires and nanofilms to obtain the in-plane thermal conductivity, electrical conductivity, and Seebeck coefficient of [(W)x(WSe2)y]z superlattice films. The measurement results show that the in-plane thermal conductivities of these films are much higher than the cross-plane values, making the thermal conductivity of the films highly anisotropic.
Numerical Investigation on Transient Natural Convection in Vertical Channels With Heated and Cooled Walls
Authors: Andreozzi Assunta , Buonomo Bernardo , Manca Oronzio
Published: April 2009

A description of transient natural convection in air in a vertical parallel plates channel, with one plate heated and the other one cooled at uniform heat flux, is numerically accomplished. The transient problem is two-dimensional and laminar with constant thermophysical properties. The numerical solution is carried out employing the commercial CFD code Fluent. The computational domain is made up of the physical configuration and two reservoirs, placed downstream and upstream the channel. Results are obtained for Rayleigh number between 103 and 106 and they are presented in terms of wall temperature profiles as a function of time, velocity and temperature profiles along transversal channel sections. The simulation allows to describe the fluid motion structures inside and outside the channel. A complete skew-symmetric motion is detected. For Ra≥105 temperature profiles as a function of time show periodical oscillations. For Ra≥104 overshoots are observed along the profiles and for corresponding average Nusselt number profiles dips are present.
Study on Behavior of Rewetting on Hot Wall
Authors: Ohtake Hiroyasu , Koizumi Yasuo , Kobayashi Shingo , Watanabe Takeshi
Published: April 2009

The behavior of rewetting on high superheated surface, focusing on rewetting temperature during collapse of saturated and subcooled film boiling was investigated experimentally and analytically. Saturated and subcooled film-boiling experiments were conducted by using a Silicon wafer with 20 mm length, 20 mm width and 0.5 mm thickness and pure water at atmospheric condition. Both pool boiling and impingement jet experiments were preformed in the present study. Then, the present experimental results were examined by using hydrodynamics instability on liquid-vapor interface (Rayleigth-Tayor instability) and a heat conduction model (rewetting model under a falling-flow of a liquid layer).
Effect of Jet Arrays and Structured Surfaces on Two-Phase Impingement Heat Transfer
Authors: Feng Xin , Bryan James E.
Published: April 2009

When heat fluxes and heat transport exceed 100 W/cm2, heat transfer efficiencies decrease rapidly. Experimental work will be presented exploring how micro jet arrays and structured surfaces can be used to increase heat transfer efficiency. Using water, ethanol, and HFE-7000 as working fluids, the effect of jet momentum, subcooling temperature and surface wetting are experimentally investigated on 1cm2 smooth and structured surfaces. From results obtained so far, heat transfer efficiency increases with increasing surface tension (decreasing surface wetting) with micro-jet arrays. Further, existing correlations for two-phase jet impingement cannot predict the heat transfer performance with acceptable accuracy as they do not account for surface wetting characteristics.
Natural Convection From a Layered Porous Cavity With Non-Uniform Sublayers
Authors: Marvel R. L. , Lai F. C.
Published: April 2009

A numerical study has been performed to further investigate the flow and temperature fields in layered porous cavity. The geometry considered is a square cavity with 3 or 4 non-uniform sublayers and is subjected to differential heating from the vertical walls. The results obtained are used to further evaluate the feasibility of using the lumped-system analysis for heat transfer in layered porous cavities as proposed in the previous study. To this end, the effective permeabilities based on the arithmetic and harmonic averaging schemes are examined for their use in the conjunction with the lumped-system analysis.
Evaluation of Thermal Characterization Techniques and Tools for Thermal Conductivity Measurement of Sub 100 Angstrom Thick Silicon Layers
Authors: Etessam-Yazdani Keivan , Asheghi Mehdi
Published: April 2009

Experimental measurement of thermal conductivity is considered the most reliable tool for the study of phonon transport in ultra-thin silicon structures. While there has been a great success in thermal conductivity measurement of ultra-thin silicon layers down to 20 nm over the past decade, it is not clear if the existing techniques and tools can be extended to the measurements of sun 100 Angstrom layers. In this paper, an analytical study of the feasibility of electrical Joule heating and thermometry in patterned metal bridges is presented. It is concluded that thermal conductivity of silicon layers as thin as 5 nm can be obtained (uncertainty 20%) by performing steady-state measurements using an on-substrate nanoheater structure. The thermal characterization of silicon layers as thin as 1 nm may be possible using frequency domain measurements.
Semi-Theoretical Modeling Oscillatory Fouling in Enhanced Tubes in Cooling Tower Systems
Authors: Li Wei
Published: April 2009

The fluctuation of fouling data, a well-known fouling phenomenon, was recognized in applications three decades ago, but it had not yet been well understood. Of specific interest is long term, combined precipitation and particulate fouling in cooling tower systems. Fouling data collected in seven 15.54 mm I.D. copper, helically ribbed tubes at water velocity (1.07 m/s) at practical conditions shows an oscillatory behavior. In order to observe it, a water temperature difference of 3.0°C, or greater, was needed for adequate accuracy based on an uncertainty analysis. Oscillatory model was used to analyze the data. The frequencies of the fluctuation are the same for the seven tested tube geometries. A series of semi-theoretical correlations of fluctuation of the long-term cooling tower water fouling data were developed. It was found that there are two ranges of amplitudes of the fluctuation based on internal parameters: linear range and non-linear range.
Moving Sheet With Variable Thermal Conductivity Emerging From a Slot
Authors: Bautista O. , Bautista E. , Me´ndez F.
Published: April 2009

In this work, we treat the heat transfer process of a continuously moving flat sheet with variable thermal conductiviy, emerging from a slot in contact with a quiescent fluid. Due to the thermal conductivity of the sheet, strong longitudinal and transverse temperature gradients arise within it, requiring to solve simultaneously the energy equation of the sheet and fluid equations. The momentum and energy balance equations are reduced to a non-linear system of partial differential equations with four parameters: the Prandtl number, Pr, a non-dimensional sheet thermal conductance β, a non-dimensional parameter identifying the effect of the variable thermal conductivity γ and a suitable Peclet number, Pe. For finite values of the parameter γ we recognize the limits β≪1 and βPe2≪1 as the most relevant from a practical point of view. In this case, the problem is governed by an universal integro-differential equation in order to obtain the spatial evolution of the sheet temperature as a function of the nondimensional longitudinal coordinate.
Effects of Cyclodextrin Solutions on Methane Hydrate Formation
Authors: Nozawa Ryo , Ferdows Mohammad , Murakami Kazuhiko , Ota Masahiro
Published: April 2009

In this paper, we suggest the advanced method of methane hydrate formation by cyclodextrin solutions. The structures of the methane hydrate were experimentally investigated by Raman spectroscopy. The induction time of the methane hydrate formation becomes by shorter 10–30 times and formation rate become by faster 2–4 times originated in the increased methane concentration of hydrate formation water by adding cyclodextrins. The results by the Raman spectroscopy indicate that the structure I methane hydrate is produced and methane molecules exist in both Large and Small cages.
Increase in voice level and speaker comfort in lecture rooms
Authors: Brunskog Jonas , Gade Anders Christian , Bellester Gaspar Payá , Calbo Lilian Reig
Published: April 2009

Teachers often suffer from health problems related to their voice. These problems are related to their working environment, including the acoustics of the lecture rooms. However, there is a lack of studies linking the room acoustic parameters to the voice produced by the speaker. In this pilot study, the main goals are to investigate whether objectively measurable parameters of the rooms can be related to an increase in the voice sound power produced by speakers and to the speakers' subjective judgments about the rooms. In six different rooms with different sizes, reverberation times, and other physical attributes, the sound power level produced by six speakers was measured. Objective room acoustic parameters were measured in the same rooms, including reverberation time and room gain, and questionnaires were handed out to people who had experience talking in the rooms. It is found that in different rooms significant changes in the sound power produced by the speaker can be found. It is also found that these changes mainly have to do with the size of the room and to the gain produced by the room. To describe this quality, a new room acoustic quantity called “room gain” is proposed.
In situ measurement of permeability
Authors: Lin Lin , Peterson M. L. , Greenberg Alan R. , McCool Benjamin A.
Published: April 2009

Permeability of a porous material with a fluid interface is shown to be related to the propagation of the slow longitudinal wave. The propagation threshold of the slow longitudinal wave occurs when the wave number is higher than the critical wave number, kcr. Measuring kcr can provide the intrinsic permeability of a porous interface. The ability to detect a change in kcr due to differences in pore size and fluid viscosity is demonstrated. This measurement is demonstrated in a model material with two pore sizes and two fluid viscosities. The results suggest opportunities to extend the method to a range of materials of scientific and technical importance.
Processing of fast speech by elderly listeners
Authors: Janse Esther
Published: April 2009

This study investigates the relative contributions of auditory and cognitive factors to the common finding that an increase in speech rate affects elderly listeners more than young listeners. Since a direct relation between non-auditory factors, such as age-related cognitive slowing, and fast speech performance has been difficult to demonstrate, the present study took an on-line, rather than off-line, approach and focused on processing time. Elderly and young listeners were presented with speech at two rates of time compression and were asked to detect pre-assigned target words as quickly as possible. A number of auditory and cognitive measures were entered in a statistical model as predictors of elderly participants’ fast speech performance: hearing acuity, an information processing rate measure, and two measures of reading speed. The results showed that hearing loss played a primary role in explaining elderly listeners’ increased difficulty with fast speech. However, non-auditory factors such as reading speed and the extent to which participants were affected by increased rate of presentation in a visual analog of the listening experiment also predicted fast speech performance differences among the elderly participants. These on-line results confirm that slowed information processing is indeed part of elderly listeners’ problem keeping up with fast language.
Effects of incident field refraction on scattered field from vertically extended cylindrical targets in range-dependent ocean waveguides
Authors: Küsel Elizabeth T. , Ratilal Purnima
Published: April 2009

The effect of incident field refraction on the scattered field from vertically extended cylindrical targets is investigated. A theoretical model for the total scattered field from a cylindrical target in a range-dependent ocean waveguide is developed from Green’s theorem. The locally scattered field on the target surface is estimated as a function of the incident field by applying the appropriate boundary conditions on continuity of acoustic pressure and normal velocity, making the model applicable to general penetrable cylinders. The model can account for depth dependence in medium sound speed and hence refraction in the incident field along the target depth. Numerical implementation is done for a passive acoustic reflector, a long cylindrical air-filled rubber hose, often deployed vertically in experiments to provide calibration and charting consistency for wide-area active sonar systems. Analysis with the model indicates that refraction in the incident field along the target depth must be taken into account to accurately estimate the scattered field level from vertically extended cylindrical targets. It is demonstrated that the standard Ingenito waveguide target scattering model, which assumes that the incident field is planar along the target extent, can lead to significant errors of 10dB or more in estimating the scattered field level.
A simplified approach to solving finite rough surface scattering problems
Authors: Fawcett J. A.
Published: April 2009

In this paper a simplified approach is described for the computation of scattering from finite length rough surfaces. In an earlier paper [Fawcett, J. Acoust. Soc. 118, 1348–1357 (2005)], it was described how to solve such problems by considering a scattering chamber and using the method of wavefield superposition to satisfy the various boundary and continuity conditions. In this paper, a form of the field in the interior of the scattering chamber is assumed and the solution to the scattering problem is reduced to solving a system of equations just along the rough surface. The solution to this system of equations can then be used to compute the scattered or total fields anywhere in the half-space. The results of this approach are compared to those obtained by other methods.
Laboratory investigation of the acoustic response of seagrass tissue in the frequency band 0.5–2.5 kHz
Authors: Wilson Preston S. , Dunton Kenneth H.
Published: April 2009

Previous in situ investigations of seagrass have revealed acoustic phenomena that depend on plant density, tissue gas content, and free bubbles produced by photosynthetic activity, but corresponding predictive models that could be used to optimize acoustic remote sensing, shallow water sonar, and mine hunting applications have not appeared. To begin to address this deficiency, low frequency (0.5–2.5 kHz) acoustic laboratory experiments were conducted on three freshly collected Texas Gulf Coast seagrass species. A one-dimensional acoustic resonator technique was used to assess the biomass and effective acoustic properties of the leaves and rhizomes of Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass). Independent biomass and gas content estimates were obtained via microscopic cross-section imagery. The acoustic results were compared to model predictions based on Wood’s equation for a two-phase medium. The effective sound speed in the plant-filled resonator was strongly dependent on plant biomass, but the Wood’s equation model (based on tissue gas content alone) could not predict the effective sound speed for the low irradiance conditions of the experiment, in which no free bubbles were generated by photosynthesis. The results corroborate previously published results obtained in situ for another seagrass species, Posidonia oceanica.
A bulk modulus dependent linear model for acoustical imaging
Authors: Mari Jean Martial , Blu Thierry , Matar Olivier Bou , Unser Michael , Cachard Christian
Published: April 2009

Modeling the acoustical process of soft biological tissue imaging and understanding the consequences of the approximations required by such modeling are key steps for accurately simulating ultrasonic scanning as well as estimating the scattering coefficient of the imaged matter. In this document, a linear solution to the inhomogeneous ultrasonic wave equation is proposed. The classical assumptions required for linearization are applied; however, no approximation is made in the mathematical development regarding density and speed of sound. This leads to an expression of the scattering term that establishes a correspondence between the signal measured by an ultrasound transducer and an intrinsic mechanical property of the imaged tissues. This expression shows that considering the scattering as a function of small variations in the density and speed of sound around their mean values along with classical assumptions in this domain is equivalent to associating the acoustical acquisition with a measure of the relative longitudinal bulk modulus. Comparison of the model proposed to Jensen’s earlier model shows that it is also appropriate to perform accurate simulations of the acoustical imaging process.
Determination of the random anisotropic elasticity layer using transient wave propagation in a fluid-solid multilayer: Model and experiments
Authors: Desceliers Christophe , Soize Christian , Grimal Quentin , Talmant Maryline , Naili Salah
Published: April 2009

The aim of this paper is to introduce a simplified model for an uncertain solid layer sandwiched between two acoustic fluid layers and using the ultrasonic characterization with an acoustic source placed in one fluid layer. Uncertainties are taken into account with a probabilistic model of the elasticity tensor. Its parameters are the mean value of the random tensor and a dispersion parameter that controls the statistical fluctuation level. The characterization of the solid layer given a database of actual measurements consists in the determination of the (i) elastic parameters of the mean elasticity model, (ii) the dispersion parameter, and (iii) mass density of the solid. This is performed with a numerical solver of wave propagation and for in vivo data collected previously. The model is representative of measurements of human bone properties with the so-called axial transmission technique. The capability of the model to predict the velocity of the first experimental arriving signal in the statistical sense is proved. The identified anisotropic elasticity tensor of cortical bone from actual data based on the simplified model is given.
Release from informational masking in children: Effect of multiple signal bursts
Authors: Leibold Lori J. , Bonino Angela Yarnell
Published: April 2009

This study examined the degree to which increasing the number of signal presentations provides children with a release from informational masking. Listeners were younger children (5–7 years), older children (8–10 years), and adults. Detection thresholds were measured for a sequence of repeating 50-ms bursts of a 1000-Hz pure-tone signal embedded in a sequence of 10- and 50-ms bursts of a random-frequency, two-tone masker. Masker bursts were played at an overall level of 60-dB sound pressure level in each interval of a two-interval, forced choice adaptive procedure. Performance was examined for conditions with two, four, five, and six signal bursts. Regardless of the number of signal bursts, thresholds for most children were higher than thresholds for most adults. Despite developmental effects in informational masking, however, masked threshold decreased with additional signal bursts by a similar amount for younger children, older children, and adults. The magnitude of masking release for both groups of children and for adults was inconsistent with absolute energy detection. Instead, increasing the number of signal bursts appears to aid children in the perceptual segregation of the fixed-frequency signal from the random-frequency masker as has been previously reported for adults [Kidd, G., et al. (2003). J. Acoust. Soc. Am. 114, 2835–2845].
A Cumulative Review of the Range and Incidence of Significant Adverse Events Associated with Acupuncture
Authors: White Adrian
Published: April 2009

Objective

To summarise the range and frequency of significant adverse events associated with acupuncture in order to provide evidence on which to base continuing efforts to improve the safety of acupuncture practice.

Methods

Searches were conducted of computerised databases, previous reviews of case reports, population surveys, prospective surveys of acupuncture practice and relevant sections of textbooks for primary and secondary reports to indicate the range of significant adverse events associated with acupuncture. Data from prospective surveys of acupuncture were combined to estimate the incidence of serious adverse events.

Results

A total of 715 adverse events was included. There were 90 primary reports of trauma, and 186 secondary reports; the most common were pneumothorax and injury to the central nervous system. Infection accounted for 204 primary reports and 91 secondary reports. Over 60% of these cases were hepatitis B. The next most common infection was of the external ear, as a complication of auricular acupuncture. The 144 miscellaneous events mainly comprised seizures and drowsiness judged severe enough to cause a traffic hazard. There were 12 primary reports of deaths. According to the evidence from 12 prospective studies which surveyed more than a million treatments, the risk of a serious adverse event with acupuncture is estimated to be 0.05 per 10 000 treatments, and 0.55 per 10 000 individual patients.

Conclusions

The risk of serious events occurring in association with acupuncture is very low, below that of many common medical treatments. The range of adverse events reported is wide and some events, specifically trauma and some episodes of infection, are likely to be avoidable.
DERIVATION OF ELECTROWEAK CHIRAL LAGRANGIAN FROM ONE FAMILY TECHNICOLOR MODEL
Authors: ZHANG HONG-HAO , FENG KAI-XI , JIANG SHAO-ZHOU , WANG QING
Published: April 2009

Based on previous studies deriving the chiral Lagrangian for pseudo scalar mesons from the first principle of QCD in the path integral formalism, we derive the electroweak chiral Lagrangian and dynamically compute all its coefficients from the one family technicolor model. The numerical results of the p4 order coefficients obtained in this paper are proportional to the technicolor number N TC and the technifermion number N TF , which agrees with the arguments in previous works, and which confirms the reliability of this dynamical computation.
TOPOLOGICAL MASS GENERATION, ELECTROWEAK SYMMETRY BREAKING AND BARYOGENESIS
Authors: BASU B. , BANDYOPADHYAY P.
Published: April 2009

We have studied here electroweak symmetry breaking and baryogenesis from the viewpoint of topological mass generation through chiral anomaly. It is shown that the SU(2) gauge symmetry of the electroweak theory breaks in two stages. In the final stage we have Z-strings produced at the phase transition. We have also studied the problem of baryogenesis in this formalism and the ratio of the baryon–antibaryon is found to be in good agreement with the observed value.
PHASE DIAGRAM OF TWO-FLAVOR QUARK MATTER: GLUONIC PHASE AT NONZERO TEMPERATURE
Authors: KIRIYAMA O.
Published: April 2009

The phase structure of neutral two-flavor quark matter at nonzero temperature is studied. Our analysis is performed within the framework of a gauged Nambu–Jona-Lasinio model and the mean-field approximation. We compute the free energy of the gluonic phase (gluonic cylindrical phase II) in a self-consistent manner and investigate the phase transition from the gluonic phase to the 2SC/g2SC/NQ phases. We briefly consider the phase diagram in the plane of coupling strength versus temperature and discuss the mixed phase consisting of the normal quark and 2SC phases.
NON-ORIENTABLE 3-MANIFOLDS ADMITTING COLORED TRIANGULATIONS WITH AT MOST 30 TETRAHEDRA
Authors: BANDIERI PAOLA , CRISTOFORI PAOLA , GAGLIARDI CARLO
Published: April 2009

We present the census of all non-orientable, closed, connected 3-manifolds admitting a rigid crystallization with at most 30 vertices. In order to obtain the above result, we generate, manipulate and compare, by suitable computer procedures, all rigid non-bipartite crystallizations up to 30 vertices.
CREDIT RISK MODELING WITH MISREPORTING AND INCOMPLETE INFORMATION
Authors: CAPPONI AGOSTINO , CVITANIĆ JAKŠA
Published: April 2009

We propose a structural model for the valuation of defaultable securities of a firm which models the effect of deliberate misreporting done by insiders in the firm and unobserved by others. We derive exact formulas for equity and bond prices and approximate expressions for the conditional default probability, recovery rate, and credit spread under the proposed credit risk framework. We propose a novel estimation approach to structural model estimation which accounts for noisy observed asset values. We apply the proposed method to calibrate a simple version of our model to the case of Parmalat and show that the model is able to recover a certain amount of misreporting during the years of accounting irregularities.
HOW DO FIRMS SOURCE EXTERNAL KNOWLEDGE FOR INNOVATION? ANALYSING EFFECTS OF DIFFERENT KNOWLEDGE SOURCING METHODS
Authors: KANG KI H. , KANG JINA
Published: April 2009

In the era of "open innovation", external knowledge is a very important source for technology innovation. In this paper, we investigate the relationship between external knowledge and performance of technology innovation. The effect of external knowledge on the performance of technology innovation can vary with different external knowledge sourcing methods. We identify three ways of external knowledge sourcing: information transfer from informal network, R&D collaboration and technology acquisition. We propose three hypotheses to examine relationship between the three methods of external knowledge sourcing and the technology innovation performance. Our results show that information transfer from informal network and technology acquisition have positive relationships with the technology innovation performance. R&D collaboration, however, has an inverted-U-shape relationship with technology innovation performance. This implies that the effect of external knowledge on technology innovation varies depending on the particular external knowledge sourcing method. This research has an important implication for firms in selecting an appropriate strategy for accessing external knowledge.
GAMMA-RAY IRRADIATION-INDUCED IMPROVEMENT OF HYDROGEN ADSORPTION IN MULTI-WALLED CARBON NANOTUBES
Authors: QIAN WEN , CHEN JIAFU , WEI LINGZHI , WU LIUSUO , CHEN QIANWANG
Published: April 2009

An improved hydrogen adsorption capacity of 0.5–0.6 wt% was obtained at room temperature and 10.0 MPa pressure for commercial MWNT sample by γ-ray irradiation, compared with 0.33 wt% of pristine MWNTs. The irradiation-induced defects in structure, which is favorable for hydrogen adsorption, were characterized by ESR spectrum, elemental analysis, and Raman spectrum. The results show that γ-ray irradiation increased the hydrogen adsorption capacity due to the increasing number of defects created by γ-photons, but would reach the maximum when defect concentration achieves saturation.
BIDIMENSIONAL EMPIRICAL MODE DECOMPOSITION USING VARIOUS INTERPOLATION TECHNIQUES
Authors: BHUIYAN SHARIF M. A. , ATTOH-OKINE NII O. , BARNER KENNETH E. , AYENU-PRAH ALBERT Y. , ADHAMI REZA R.
Published: April 2009

Scattered data interpolation is an essential part of bidimensional empirical mode decomposition (BEMD) of an image. In the decomposition process, local maxima and minima of the image are extracted at each iteration and then interpolated to form the upper and the lower envelopes, respectively. The number of two-dimensional intrinsic mode functions resulting from the decomposition and their properties are highly dependent on the method of interpolation. Though a few methods of interpolation have been tested and/or applied to the BEMD process, many others remain to be tested. This paper evaluates the performance of some of the widely used surface interpolation techniques to identify one or more good choices of such methods for envelope estimation in BEMD. The interpolation techniques studied in this paper include various radial basis function interpolators and Delaunay triangulation based interpolators. The analysis is done first using a synthetic texture image and then using two different real texture images. Simulations are made to focus mainly on the effect of interpolation methods by providing less or negligible control on the other parameters or factors of the BEMD process.
EMPIRIC AND DYNAMIC DETECTION OF THE SEA BOTTOM TOPOGRAPHY FROM SYNTHETIC APERTURE RADAR IMAGE
Authors: YUAN YELI , JIN MEIBIN , SONG PINGJIAN , ZHANG JIE
Published: April 2009

In this study, we develop empiric and dynamic methods to detect the underlying sea bottom topography from synthetic aperture radar (SAR) images. The ocean bottom features can be seen from SAR images due to the modulation of the surface waves by the nonuniform currents, which, by motion equations, should be a function of depth. We first derive the SAR image equation at a given time from Valenzuela's formula and the expression of micro-scale wave spectrum. By integrating the SAR image equation and the governing equations for ocean currents, we establish the "forward and inverse problems" for dynamic detection of topography. To utilize the SAR images, we separate the current modulation scale from the surface waves by a two-dimensional empirical mode decomposition method based on the Delaunay triangulation with the most protruding principle and the Berstein–Bezier fitting and interpolation with the most optimum principle. Examples of bottom topography detection from SAR images are presented.
IMAGE EMPIRICAL MODE DECOMPOSITION: A NEW TOOL FOR IMAGE PROCESSING
Authors: LINDERHED ANNA
Published: April 2009

Image empirical mode decomposition (IEMD) is an empirical mode decomposition concept used in Hilbert–Huang transform (HHT) expanded into two dimensions for the use on images. IEMD provides a tool for image processing by its special ability to locally separate superposed spatial frequencies. The tendency is that the intrinsic mode functions (IMFs) other than the first are low-frequency images. In this study we give an overview of the state-of-the-art methods to decompose an image into a number of IMFs and a residue image with a minimum number of extrema points, together with the use of the method. Ideas and open problems are presented.
PCR NONADAPTIVE GROUP TESTING OF DNA LIBRARIES FOR BIOMOLECULAR COMPUTING AND TAGGANT APPLICATIONS
Authors: MACULA ANTHONY J. , GAL SUSANNAH , ANDAM CHERYL , BISHOP MORGAN A. , RENZ THOMAS E.
Published: April 2009

Using a universal and parallel battery of PCR reactions, we give a nonadaptive group testing method for identifying the individual strands in a pooled sample of several different DNA sequences taken from a DNA library. The method discussed here has potential applications to DNA taggants, DNA memory and DNA computing.
ANALYZING NONBLOCKING MULTILOG NETWORKS WITH THE KÖNIG–EGEVARÝ THEOREM
Authors: NGO HUNG Q. , NGUYEN THANH-NHAN , HA DUC T.
Published: April 2009

When analyzing a nonblocking switching network, the typical problem is to find a route for a new request through the network without disturbing existing routes. By solving this problem, we can derive how many hardware components of a certain type (Banyan planes in a multi-log network, for instance) are needed for the network to be nonblocking. This scenario appears in virtually all combinations of switching environments: strictly, widesense or rearrangeably nonblocking, unicast or multicast switching, and circuit, multirate, or photonic switching.

In this paper, we show that the König–Egevarý theorem is a very good tool which helps solve the above prototypical problem. The idea is to somehow "represent" the potential blocking connections as edges of a bipartite graph. The maximum number of blocking connections roughly corresponds to the size of a maximum matching in that bipartite graph. The size of any vertex cover, by the König–Egevarý theorem, is an upper bound on the maximum number of blocking connections. Thus, by specifying a small vertex cover, we can derive the sufficient number of hardware components for the network to be nonblocking. We illustrate the technique by analyzing crosstalk-free and non-crosstalk-free widesense nonblocking multicast multi-log networks.

Particularly, for the first time in the literature we derive conditions for the d-ary multi-log network to be crosstalk-free multicast widesense nonblocking under the window algorithm for any given window size. Several by-products follow from our approach and results. Firstly, our results allow for computing the best window size minimizing the fabric cost, showing that the multi-log network is a good candidate for crosstalk-free multicast switching architectures. Secondly, the analytical approach also gives a much simpler proof of the known case when the network is not required to be crosstalk-free. Thirdly, we show that several known results for the multi-log multicast networks under the so-called fanout constraints are simple corollaries of our results.
Distinguishing Conjoint and Independent Neural Tuning for Stimulus Features With fMRI Adaptation
Authors: Drucker Daniel M. , Kerr Wesley Thomas , Aguirre Geoffrey Karl
Published: April 2009

A central focus of cognitive neuroscience is identification of the neural codes that represent stimulus dimensions. One common theme is the study of whether dimensions, such as color and shape, are encoded independently by separate pools of neurons or are represented by neurons conjointly tuned for both properties. We describe an application of functional magnetic resonance imaging (fMRI) adaptation to distinguish between independent and conjoint neural representations of dimensions by examining the neural signal evoked by changes in one versus two stimulus dimensions and considering the metric of two-dimension additivity. We describe how a continuous carry-over paradigm may be used to efficiently estimate this metric. The assumptions of the method are examined as are optimizations. Finally, we demonstrate that the method produces the expected result for fMRI data collected from ventral occipitotemporal cortex while subjects viewed sets of shapes predicted to be represented by conjoint or independent neural tuning.
Computational kinetic model of VEGF trapping by soluble VEGF receptor-1: effects of transendothelial and lymphatic macromolecular transport
Authors: Wu Florence T. H. , Stefanini Marianne O. , Mac Gabhann Feilim , Kontos Christopher D. , Annex Brian H. , Popel Aleksander S.
Published: April 2009

Vascular endothelial growth factor (VEGF) signal transduction through the cell surface receptors VEGFR1 and VEGFR2 regulates angiogenesis—the growth of new capillaries from preexistent microvasculature. Soluble VEGF receptor-1 (sVEGFR1), a nonsignaling truncated variant of VEGFR1, has been postulated to inhibit angiogenic signaling via direct sequestration of VEGF ligands or dominant-negative heterodimerization with surface VEGFRs. The relative contributions of these two mechanisms to sVEGFR1's purported antiangiogenic effects in vivo are currently unknown. We previously developed a computational model for predicting the compartmental distributions of VEGF and sVEGFR1 throughout the healthy human body by simulating the molecular interaction networks of the VEGF ligand-receptor system as well as intercompartmental macromolecular biotransport processes. In this study, we decipher the dynamic processes that led to our prior prediction that sVEGFR1, through its ligand trapping mechanism alone, does not demonstrate significant steady-state antiangiogenic effects. We show that sVEGFR1-facilitated tissue-to-blood shuttling of VEGF accounts for a counterintuitive and drastic elevation in plasma free VEGF concentrations after both intramuscular and intravascular sVEGFR1 infusion. While increasing intramuscular VEGF production reduces free sVEGFR1 levels through increased VEGF-sVEGFR1 complex formation, we demonstrate a competing and opposite effect in which increased VEGF occupancy of neuropilin-1 (NRP1) and the corresponding reduction in NRP1 availability for internalization of sVEGFR1 unexpectedly increases free sVEGFR1 levels. In conclusion, dynamic intercompartmental transport processes give rise to our surprising prediction that VEGF trapping alone does not account for sVEGFR1's antiangiogenic potential. sVEGFR1's interactions with cell surface receptors such as NRP1 are also expected to affect its molecular interplay with VEGF.
PTTG Overexpression Promotes Lymph Node Metastasis in Human Esophageal Squamous Cell Carcinoma
Authors: Yan Shuang , Zhou Cuiqi , Lou Xiaomin , Xiao Zefen , Zhu Hongxia , Wang Qifeng , Wang Yihua , Lu Ning , He Shun , Zhan Qimin , Liu Siqi , Xu Ningzhi
Published: April 2009

Human pituitary tumor transforming gene (PTTG) overexpression correlates with metastasis in multiple tumors, and yet its molecular mechanisms of action remain elusive. We detected PTTG overexpression in 66% (111 of 169) of primary esophageal squamous cell carcinoma (ESCC) tumor tissues by in situ hybridization. PTTG overexpression correlated with lymph node metastasis (P < 0.05). Ectopic PTTG overexpression in a representative ESCC cell line, EC9706, increased in vitro cell migration and invasion and promoted in vivo lymph node metastasis. Suppressing PTTG expression by siRNA decreased cell motility in both PTTG-HA/EC9706 and KYSE150 cells. By using mass spectrometric analysis, we identified that PTTG up-regulated S100A4 and galectin-1 secretion and down-regulated tissue inhibitor of metalloproteinase-2 secretion to the culture media. PTTG induced S100A4 and galectin-1 mRNA and protein expression as assessed by Western blot and reverse transcription-PCR. Attenuating galectin-1 expression by siRNA constrained PTTG-HA/EC9706 cell motility (P < 0.05). PTTG activated E-box transcription and induced c-Myc protein expression in EC9706 cells, which in turn may act on an E-box motif within the galectin-1 promoter. Chromatin immunoprecipitation assays further confirmed specific c-Myc binding to galectin-1 promoter. PTTG-induced galectin-1 transactivation and expression were mediated by c-Myc, and both inductions were suppressed by c-Myc RNAi cotranfection. These findings elucidate the molecular mechanisms of PTTG overexpression in promoting tumor metastasis, whereby up-regulated PTTG modulates expression and secretion of metastasis-related factors to facilitate cell motility. [Cancer Res 2009;69(8):3283–90]