bluuebunny/crossref_metadata_2025 huggingface dataset:
One-Dimensional Numerical Investigation of a Cylindrical Micro Combustor
Authors: Irani R. A. , Saediamiri M. , Saidi M. S. , Saidi M. H. , Shafii M. B.
Published: June 2010

In this paper, a one-dimensional numerical approach is used to study the effect of various parameters such as micro combustor diameter, mass flow rate and external convection heat transfer coefficient on the temperature and species mass fraction profiles. A premixed mixture of H2-Air with a multi-step chemistry (9 species and 19 reactions) is used and thermal conductivity of the mixture is considered as a function of species thermal conductivity and temperature by using a set of new relations. The transient gas phase energy and species conservation equations result in an Advection-Diffusion-Reaction system (A-D-R) that leads to two stiff systems of PDEs, which can not be solved by conventional Computational Fluid Dynamics (CFD) methods. In the present work, Strang splitting method, which is suitable for nonlinear stiff system of PDEs, is used. The results show that both convection heat transfer coefficient and micro combustor diameter have a significant effect on the combustion and heat transfer rates in the micro scales. Also, increasing the convective heat transfer coefficient and decreasing the diameter and inlet mixture velocity, decreases the temperature and active radicals along the micro combustor.
Generation of Water Channel During Melting Process of an Ice Packed Bed
Authors: Murakami Kengo , Asaoka Tatsunori , Okada Masashi , Teraoka Yoshikazu
Published: June 2010

In the melting process of a packed bed of ice particles in an ice thermal storage tank, water channel is formed by non homogeneity melting. Water channel causes some problems such as the decrease of heat exchange rate and the increase of residual of ice. In this study, the generation of water channel during melting process of an ice packed bed was investigated. The experiment and numerical analysis of melting of an ice packed bed were performed in a two-dimensional model. In this model, water at 0°C flows through the ice packed bed continuously. In order to realize the non homogeneous melting, the ice packed bed was intentionally melted by a line heat source. In the experiment, the shape of melting front in the ice packed bed was observed on some typical conditions. The effects of the permeability and porosity distribution in the ice packed bed and the flow velocity of water on the shape of melting front were investigated in the numerical analysis. As a result, it was found that the growth rate of water channel is affected by the permeability in the ice packed bed and the flow velocity of water. It was also found that the results of the numerical analysis considering the porosity distribution of the packed bed correspond to the experimental results.
Laminar Slug Flow: Heat Transfer Characteristics With Constant Heat Flux Boundary
Authors: Walsh P. A. , Walsh E. J. , Muzychka Y. S.
Published: June 2010

The problem of elevated heat flux in modern electronics has led to the development of numerous liquid cooling devices which yield superior heat transfer coefficients over their air based counterparts. This study investigates the use of liquid/gas slug flows where a liquid coolant is segregated into discrete slugs, resulting in a segmented flow, and heat transfer rates are enhanced by an internal circulation within slugs. This circulation directs cooler fluid from the center of the slug towards the heated surface and elevates the temperature difference at the wall. An experimental facility is built to examine this problem in circular tube flow with a constant wall heat flux boundary condition. This was attained by Joule heating a thin walled stainless steel tube. Water was used as the coolant and air as the segregating phase. The flow rates of each were controlled using high precision syringe pumps and a slug producing mechanism was introduced for segmenting the flow into slugs of various lengths at any particular flow rate. Tube flows with Reynolds numbers in the range 10 to 1500 were examined ensuring a well ordered segmented flow throughout. Heat transfer performance was calculated by measuring the exterior temperature of the thin tube wall at various locations using an Infrared camera. Nusselt number results are presented for inverse Graetz numbers over four decades, which spans both the thermally developing and developed regions. The results show that Nu in the early thermally developing region are slightly inferior to single phase flows for heat transfer performance but become far superior at higher values of inverse Gr. Additionally, the slug length plays an important role in maximizing Nusselt number in the fully developed region as Nu plateaus at different levels for slugs of differing lengths. Overall, this paper provides a new body of experimental findings relating to segmented flow heat transfer in constant heat flux tubes without boiling. Put abstract text here.
Numerical Simulation of Magneto-Convection in an Enclosure
Authors: Ghassemi M. , Pirmohammadi M.
Published: June 2010

Natural-convection flow in the presence of a magnetic field in an enclosure heated from bottom and cooled from top is considered. The fluid (molten sodium) properties are function of temperature. To solve the governing non-linear differential equations (mass, momentum and energy) a finite volume code based on PATANKAR’s SIMPLER method is utilized. The results for different Rayleigh and Hartmann numbers show that the strength of the magnetic field has significant effects on the flow and temperature fields. The convection becomes stronger as the Rayleigh number increases while the magnetic field suppresses the convective flow and the heat transfer rate. When the magnetic field is weak and the Rayleigh number is high, the convection is dominant.
A 2D-PIV Study on Natural Convective Heat Transfer in a Square Enclosure With Partially Active Side Walls
Authors: Paroncini Massimo , Corvaro Francesco , Montucchiari Alessia
Published: June 2010

The present study is an experimental and numerical analysis on the natural convection of air in square enclosures with partially active side walls. The experimental equipment is based on two different systems: an holographic interferometer and a 2D-PIV. The test cell is a square enclosure filled of air with vertical partially active side walls at different temperatures. The hot and cold regions on these sides are located in the middle of the cavity. The remaining vertical walls are made up of glass to allow an optical access to the cavity. The top and bottom surfaces of the enclosure are made up of plexiglas to reduce heat leakages. The experimental study is carried out both through the holographic interferometry, in order to obtain the average Nusselt numbers at different Rayleigh numbers, and through the 2D-PIV, in order to analyse the dynamic behaviour of the phenomenon at the same Rayleigh numbers. The average Nusselt numbers are obtained measuring the temperature distribution in the air layer trough the real-time and double-exposure holographic interferometry; the dynamic structures are the velocity vector distribution, the streamlines and the velocity maps. Finally these experimental data are compared to the results obtained through a numerical study carried out using the finite volume code, Fluent 6.2.3. The aim of this comparison is the validation of the numerical procedure. In this way it is possible to use the numerical code to enlarge the Rayleigh number range.
Effect of Turbulent Prandtl Number on Convective Heat Transfer to Turbulent Upflow of Supercritical Carbon Dioxide
Authors: Bazargan Majid , Mohseni Mahdi
Published: June 2010

A two-dimensional model is developed to simultaneously solve the momentum and energy equations and thus predict convection heat transfer to an upward flow of supercritical carbon dioxide in a round tube. The effect of the turbulent Prandtl number, Prt, on heat transfer coefficients has been extensively studied. A number of constant values of Prt, as well as a number of suggested equations accounting for variations of Prt with flow conditions, have been examined. The investigation has been carried out for both regimes of enhanced and deteriorated heat transfer. The results of this study show that the increase of Prt, even in the viscous sublayer, cause the heat transfer coefficients to decrease. The models of Prt leading to best agreement with experiments in either regimes of heat transfer were recognized. From the effect Prt has on heat transfer coefficients, it has been deduced that the buoyancy effects in upward flow of a supercritical fluid causes the Prt to decrease and hence the heat transfer coefficients to increase.
Modeling of Free Convection Heat Transfer to a Supercritical Fluid in a Square Enclosure by the Lattice Boltzmann Method
Authors: Bazargan Majid , Varmazyar Mostafa
Published: June 2010

During the last decade a number of numerical computations based on the finite volume approach have been reported studying various aspects of heat transfer near the critical point. In this paper, a Lattice Boltzmann Method (LBM) has been developed to simulate laminar free convection heat transfer to a supercritical fluid in a square enclosure. The LBM is an ideal mesoscopic approach to solve nonlinear macroscopic conservation equations due to its simplicity and capability of parallelization. The Lattice Boltzmann Equation (LBE) represents the minimal form of the Boltzmann kinetic equation. The LBE is a very elegant and simple equation, for a discrete density distribution function and is the basis of the LBM. For the mass and momentum equations, an LBM is used while the heat equation is solved numerically by a finite volume scheme. In this study, inter-particle forces are taken into account for non-ideal gases in order to simulate the velocity profile more accurately. The laminar free convection cavity flow has been extensively used as a benchmark test to evaluate the accuracy of the numerical code. It is found that the numerical results of this study are in good agreement with the experimental and numerical results reported in the literature. The results of the LBM–FVM combination are found to be in excellent agreement with the FVM–FVM combination for the Navier-Stokes and heat transfer equations.
Experimental Study on the Effect of Viscous Heating on the Temperature Field in Microchannel Gas Flow
Authors: Zhang T. T. , Jia L. , Li C. W. , Jaluria Y.
Published: June 2010

An experimental system for single-phase gas flow in microchannels was set up. The effects of viscous heating on the temperature field in the flow were studied experimentally. Also, a theoretical model for the flow and heat transfer in the slip flow region was developed and the resulting equations were solved analytically by using a method based on the superposition principle. The results obtained agree well with the experimental data. The study also provides greater insight into microchannel flow and the associated heat transfer.
Utilizing Disk Shaped Thermistors to Experimentally Determine the Prandtl Number Dependence Ranging From Vapors to Liquids
Authors: Kobus Chris J.
Published: June 2010

The current research utilizes disk-shaped thermistors to indirectly measure the convective heat transfer coefficient in the case of natural convection. Thermistors are resistors which have a resistance that is extremely temperature sensitive, so that experiments can be run with exceptional resolution. Not only can the convective heat transfer be indirectly measured, but so can the surface temperature, without the need for external temperature sensors which can interfere with the phenomena itself. Utilizing these themistors, heat transfer data was taken utilizing a variety of fluids from gasses (Pr = 0.72) to heavy oils (Pr ∼ 1000). From the experimental data, it was shown that the classical Nusselt-Rayleigh type correlation does not accurately predict the Prandtl number dependence for this geometry, and a new dimensionless correlation is proposed.
Feedback Control of Heat Transfer Systems by the Numerical Method of Lines
Authors: Brown David , Zhang Chao , Jiang Jin
Published: June 2010

A direct method for feedback optimal control of fluid flow and heat transfer systems is investigated. The method consists of discretizing the spatial component of the governing partial differential equations using standard finite-volume methods (FVM) while leaving the transient term in its differential form. This partial discretization method is commonly known as the Numerical Method of Lines (NUMOL). The control is then applied to the partially discretized system of linear ordinary time differential equations. Of particular interest is the effectiveness of linearizing about the current state rather than the origin. The effectiveness of this method is investigated through numerical implementation on a simple one-dimensional heat transfer system.
Thermal Rectification by Ballistic Phonons in Asymmetric Nanostructures
Authors: Miller John , Jang Wanyoung , Dames Chris
Published: June 2010

In analogy to an electrical diode, a thermal rectifier transports heat more easily in one direction than in the reverse direction. Among various possible nanoscale rectification mechanisms, a ballistic rectifier relies on asymmetric scattering of energy carriers, as has been suggested for phonon transport in a sawtooth nanowire [S. Saha, L. Shi, & R. Prasher, IMECE 2006] or nanowire with special surface specularity function [N.A. Roberts and D.G. Walker, ITherm 2008]. We have used a Landauer-Buttiker method as well as a Monte Carlo method to model the asymmetric heat transport in such nanostructures, with careful attention to boundary conditions that satisfy the 2nd Law of Thermodynamics. The calculations show that ballistic rectification is only significant at relatively large “thermal bias,” which causes significant anisotropy in the distribution function of energy carriers emitted at each of the two thermal contacts. We also propose experiments to observe this phenomenon using either phonons or photons.
Prediction of the Effective Thermal Diffusivity of Discretely Inhomogeneous Media
Authors: Mackowski Daniel W. , Ramos Mario
Published: June 2010

An extended definition of the effective thermal diffusivity is posed via an analogy to acoustic and EM wave propagation in discretely inhomogeneous media. Specifically, the propagation of a periodic, plane thermal wave of frequency ω, through an inhomogeneous medium consisting of spherical particles embedded in a continuous matrix, is theoretically examined. An exact solution for the time–harmonic conduction equation, for the multiple sphere system, is developed by use of the scalar wave harmonic functions and the addition theorem for the harmonics. An effective medium model, which is based on the Quasi–Crystalline approximation (QCA) for acoustic and EM wave propagation, is developed, and a formulation for the frequency–dependent effective thermal diffusivity is derived. In the limit of x = Rω/α0→0, where R is the sphere radius and α0 the matrix thermal diffusivity, it is shown that formulation reduces to that derived from a static model.
A Near-Wall Interfacial Area Concentration Model to Predict Departure From Nucleate Boiling Critical Heat Flux Based on High Speed Video From Boiling Water Flows
Authors: Hurlburt Evan T. , Krenitsky Helene A. , Bauer Richard C.
Published: June 2010

In nucleate boiling as the heat flux from the wall to the fluid is increased the heat transfer coefficient initially increases. At a sufficiently high heat flux called the critical heat flux (CHF) the heat transfer mechanism suddenly becomes less effective resulting in a rapid jump in wall temperature. In bubbly subcooled (or near-subcooled) conditions the CHF mechanism is referred to as departure from nucleate boiling. Departure from nucleate boiling (DNB) refers to the transition from nucleate boiling where liquid contacts the wall to film boiling in which a vapor layer contacts the wall. Various hypotheses have been used in modeling and predicting CHF. High speed video images of boiling water flows taken at Bettis Laboratory at the critical heat flux visually captured sufficient evidence of the DNB mechanism that improved insight into DNB modeling may be possible. This paper summarizes high speed video image analysis and the development of a new DNB critical heat flux model based on the image analysis findings. Using short window averages of image data, a significant increase in transmitted light intensity is seen near the wall just prior to CHF. The increase suggests that at CHF there is a transient reduction in the interfacial area concentration, ai, or bubble number density near the wall. This is believed to be the result of a sudden increase in bubble coalescence rates near the wall. The increase in coalescence rates results in a reduction in the interfacial area concentration causing it to reach a maximum at CHF. This near-wall maximum in ai at CHF under flow boiling conditions is consistent with recent pool boiling data in the literature. The image based observations motivated development of an interfacial area based CHF model to predict the maximum in the interfacial area concentration at CHF. The model predicts that a critical nucleation site density or a near-wall critical void fraction can be used as a DNB CHF criterion. This is a valuable simplification that can be directly implemented in three-dimensional thermal hydraulic codes. The critical nucleation site density result was used as an input to a simple wall heat transfer partition model to predict the critical heat flux. The model relies on correlation based estimates for the superheat temperature, bubble departure diameter, and bubble departure frequency. Model predictions are compared to CHF values taken from Groeneveld’s 2006 CHF look-up table.
Calibration of the Sandia One-Dimensional Direct and Inverse Thermal (SODDIT) Code for Estimating Heat Flux to a Large Pipe Calorimeter in a Jet Fuel Fire
Authors: Bullard Tim , Greiner Miles
Published: June 2010

Industry and safety standards demand the knowledge of the thermal behavior of systems subjected to fire, particularly for the transportation of radioactive materials for spent nuclear fuel disposal and reprocessing. Experimentally benchmarked fire test data from Container Analysis Fire Environment (CAFE) are used to calibrate the Sandia One Dimensional Direct and Inverse Thermal (SODDIT) code by optimizing number of future times (NFT) at 11 and identifying a linear correlation and uncertainty range between the SODDIT input and output. The calibration is then used to predict the heat flux to a large pipe calorimeter in a jet fuel fire, for which the result is an 11 second window average of the actual heat flux. The maximum heat flux occurred at the beginning of the fire and was found to be 195 ± 37.3 kW/m2 at a 95% confidence level.
Theoretical Investigation of Tip-Based Nanoscale Infrared Spectroscopy
Authors: Dipippo William , Lee Bong Jae , Park Keunhan
Published: June 2010

The ability to conduct the chemical analysis of materials with the nanoscale spatial resolution has been a long term thrust in many science and engineering communities. Although several techniques such as chemical force microscopy [1] and tip-enhanced Raman spectroscopy [2] have been developed for the nanoscale chemical analysis, there still exist technical challenges in routinely achieving a full spectrum of chemical information at the nanoscale. The main objective of this study is to propose a novel tip-based nanoscale infrared (IR) spectroscopy by combining the atomic force microscopy (AFM) and the Fourier-transformed infrared (FT-IR) spectroscopy.
Interfacial Thermal Transport in Carbon Nanotubes
Authors: Kumar Satish , Murthy Jayathi Y.
Published: June 2010

There is significant amount of research to analyze the thermal, electrical and other physical properties of carbon nanotubes (CNTs). However, the energy transport mechanism at the contact of two tubes is still not well understood. This study investigates the interfacial thermal interaction between two carbon nanotubes using molecular dynamics simulation and wavelet methods. We place the tubes in a crossed configuration and pass a high temperature pulse along one of the CNTs while keeping other ends fixed, and analyze the interaction of this pulse with other nanotube. We apply this technique for nanotubes of chirality in the range of (5,0) to (10,0) to observe the response of tubes with changing diameter. This thermal pulse analysis shows that the coupling between the two tubes is very weak and may be dominated by the slow moving phonon modes with high energy. We perform a wavelet analysis of thermal pulse propagation along a CNT and its impact on another CNT in cross contact. Wavelet transformations of the heat pulse show how different phonon modes are excited and how they evolve and propagate along the tube axis depending on its chirality.
Laminar Natural Convection in an Air-Filled Square Cavity With Partitions on the Top Wall
Authors: Wu Wenjiang , Ching Chan Y.
Published: June 2010

The laminar natural convection in an air-filled square cavity with a partition on the top wall was experimentally investigated. Temperature measurements and flow visualizations were performed for cases with heated and cooled vertical walls (corresponding to a global Grashof number GrH of approximately 1.3 × 108) and non-dimensional top wall temperatures θT of 0.56 (insulated) to 2.3. Experiments were performed with an aluminum partition with non-dimensional height HP/H of 0.0625 and 0.125 attached to the top wall at x/H = 0.1, 0.2, 0.4 and 0.6. The blockage effect and/or the thermal effect of the partition resulted in changes to the temperature and flow fields, but were mainly limited to the vicinity of the partition. The partition on the heated top wall resulted in a recirculating flow between the partition and the heated vertical wall. For a given partition height, the structure of this recirculating flow was dependent on the partition location and θT. A thermal boundary layer developed along the rear surface of the partition due to the thermal effect of the partition. The ambient temperature outside the boundary layer and Nu near the corner region were affected by the partition height due to the changes in the recirculating flow and due to the thermal effect on the rear surface of the partition.
Effect of Size and Slip Coefficient of a Porous Manifold on Thermal Stratification in Storage Tanks
Authors: Brown N. M. , Lai F. C.
Published: June 2010

Numerical simulations have been performed to study the effects of size and slip coefficient of a porous manifold on the thermal stratification in a storage tank. The model is used to predict the development of flow and temperature fields during a charging process. Computations have covered a wide range of the Grashof number (1.8 × 105 < Gr < 1.8 × 108) and Reynolds number (10 ≤ Re ≤ 104), or in terms of the Richardson number, 10−2 < Ri < 105. The results obtained compare favorably well with the experimental data. In addition, the present results have confirmed the effectiveness of porous manifold in the promotion of thermal stratification and provide useful information for the design of such system.
Natural Convection Heat Transfer From Vertical Triangular Ducts
Authors: Ali Mohamed E. , Al-Ansary Hany
Published: June 2010

Experimental investigations have been reported on steady state natural convection from the outer surface of vertical triangular cross section ducts in air. Three ducts have been used with equilateral side length of 0.044, 0.06 and 0.08 m. The ducts are heated using internal constant heat flux heating elements. The temperatures along the vertical surface and the peripheral directions of the duct wall are measured. Axial (perimeter averaged) heat transfer coefficients along the side of each duct are obtained for laminar and transition to turbulent regimes of natural convection heat transfer. Axial (perimeter averaged) Nusselt numbers are evaluated and correlated using the modified Rayleigh numbers for laminar and transition regime using the vertical axial distance as a characteristic length. Critical values of the modified Rayleigh numbers are obtained for transition to turbulent. Furthermore, total overall averaged Nusselt numbers are correlated with the modified Rayleigh numbers for all ducts. The local axial (perimeter averaged) heat transfer coefficients are observed to decrease in the laminar region and increase in the transition region. Laminar regimes are obtained at the lower half of the ducts and its chance to appear decreases as the heat flux increases.
The Impact of Supercooling on the Effective Cooling Storage Capacity of Phase-Change Materials in Natural Cooling Application
Authors: Niu Jianlei , Zhang Shuo
Published: June 2010

Ice storage is currently the dominant cooling energy storage method. To more effectively utilize natural, renewable cooling sources, such as evaporative cooling and sky-radiative cooling, diurnal storage media operated on daily basis at the temperate range between 10 and 20 °C are the most desirable. In this paper, we presented our experimental investigation of micro-encapsulated paraffin slurry as cooling storage media for building cooling applications. The water slurry of micro-encapsulated N-hexadecane with a melting temperature of 18 °C were cooled to 5 °C and heated to 25 °C cyclically in a storage tank of 230 litre, and it was observed that full latent heat storage can only be realized at 5 °C due to supercooling, and the effective cooling storage capacity at the cooling temperature between 5 and 18 °C are obtained, which can be used to for cooling storage system design with various passive cooling possibilities.
The Effect of Conductive and Non-Conductive Flow Diverters on Free Convection Heat Transfer From a Vertical Array of Horizontal Isothermal Cylinders
Authors: Razi Pooyan , Moghadassian Behnam , Shokouhmand Hossein
Published: June 2010

In this paper, a numerical solution method (finite volume) has been applied to investigate the effect of conductive and non-conductive flow diverters on free convection heat transfer from a vertical array of horizontal isothermal cylinders. Cylinder vertical spacings (center to center distance = S) of 2D, 3D and 4D has been investigated, which D is the cylinder diameter. Rectangular plate diverters have been placed between cylinders. Diverters are tilted at different angels with respect to horizon. The calculation has been done for various Rayleigh numbers based on the cylinder-diameter in the range between 103 and 104. The results show that in the case of 2D cylinder spacing, both conductive and non-conductive flow diverters decrease the heat transfer rate of cylinders at low Rayleigh numbers. However, as the distance between the cylinders increases to 3D and 4D, adding flow diverters leads to an increase in the heat transfer rate of the array. Also, in the cases of 3D and 4D spacing, the use of non-conductive flow diverters results in more increase in heat transfer rate in comparison with the rate of heat transfer resulted by applying conductive diverters.
Using Infrared Thermography for Detecting Defects on Surfaces With Low and Variable Emissivity
Authors: Dalton Christopher , Olson Brandon , Lai Feng C.
Published: June 2010

Currently infrared scanning technology has been successfully applied for the detection of a wide variety of defects in many applications provided that the surfaces have a high emissivity that doesn’t reflect radiation from outside sources. However, surfaces with low and variable emissivity present a challenge for the application of this technology because infrared cameras and sensors cannot differentiate between the emitted radiation from the surface of interest and those reflected from outside sources. The system presented is an attempt to reduce and/or remove the effects of reflected radiation to increase the system’s applicability beyond the limit of high emissivity surfaces. Physical hardware and computer software are used in concert with radiative heat transfer equations to first determine the emissivity of each point on the surface, then use that information obtained to accurately depict the surface temperature. While this newest iteration of the system development has addressed many important issues regarding accuracy, efficiency as well as performance enhancement in the removal of the artifacts of reflected radiation, the technique still has difficulties to be applied to most surfaces with variable emissivity.
A randomised controlled trial of subcutaneous sodium salicylate therapy for osteoarthritis of the thumb
Authors: Smith A S , Doré C J , Dennis L , Julius A , Mackworth-Young C G
Published: June 2010

Background

Current treatment for osteoarthritis (OA) is limited. Many patients with OA of the hand have areas of tender subcutaneous thickening in the forearm and upper scapular region. A pilot study showed an improvement in pain from OA at the first carpometacarpal joint after injection of such areas with 0.5% sodium salicylate or saline, an inexpensive treatment that can be administered by general practitioners and nurses. The study indicated that a randomised, sham-controlled trial was justified.

Methods

40 patients with OA of the first carpometacarpal joint were randomised to receive either injections of sodium salicylate into tender, thickened areas of subcutaneous tissue on the forearm (baseline) and upper scapular region (week 1) or sham injections consisting of pressure without skin penetration. Blinded assessments were made at weeks 3, 7 and 13 after baseline.

Results

Pain and tenderness during follow-up were both significantly lower in the active treatment group compared with the sham group: 19% and 14% greater reduction in mean visual analogue scale (VAS) score, respectively (p=0.007 and 0.02, baseline mean 5.65 and 5.35 cm, average difference in change from baseline VAS 1.9 and 1.4 cm, 95% CI 0.6 to 3.2 and 0.2 to 2.5). Active and sham injections were painful, the former significantly more so; however, there was no significant correlation between the pain of active injections and response.

Conclusion

The data show that subcutaneous sodium salicylate injections are an effective symptomatic treatment for OA of the thumb. The results provide a basis for further physiological and therapeutic research in this area.
Should there be a visual standard for ophthalmologists and other surgeons?
Authors: Wong Newton W K , Stokes John , Foss Alexander J E , McGraw Paul V
Published: June 2010

A number of professions have a visual standard but there is no standard for surgeons, including surgeons such as ophthalmologists who operate with the aid of a microscope. We review which professions do have a visual standard, the evidence addressing the issue of a visual standard in medicine and surgery, and an international survey of what visual standards other countries apply to ophthalmologists, and performed a survey of the views of the member of the British Royal College of Ophthalmologists. A number of professions, where public safety is an issue, do have a visual standard without compelling supporting evidence. By contrast, all but two countries do not have a visual standard for their ophthalmic surgeons. The survey of members of the British Royal College of Ophthalmologists supported the adoption of such a standard, which would include minimum requirements for both visual acuity and stereoacuity. Good vision is clearly essential for ophthalmologists, as well as for other surgeons and practioners of some other branches of medicine. While there is no evidence to support a specific visual standard, we conclude that one should be adopted until there is definitive evidence to settle the issue on the basis of the precautionary principle as patient safety is involved.
A reappraisal of the role of ‘mindbody’ factors in chronic urticaria
Authors: Broom Brian C
Published: June 2010

Chronic spontaneous urticaria (CSU) is a very common skin condition that causes considerable suffering and is often poorly responsive to drug treatment regimens. Most clinicians accept that multiple factors play a role in the aetiology of CSU, but there is a widespread reluctance to accept a significant role for ‘mindbody’ factors, despite a large number of clinical reports and studies over many decades suggesting their relevance. This reluctance has multiple origins. A primary influence is the flawed dualistic model of mind and body relatedness underpinning much of modern medical care. In this view, if a pathophysiological mechanism can be discerned, then ‘mind’ factors can be largely ignored. Recent evidence demonstrating intimate structural and functional relations between peripheral nerves and mast cells, and local skin secretion of mast cell-influencing neuropeptides by nerves, provides an argument for discarding old ‘organic’ and dualistic conceptualisations of CSU. A sound, integrative, multifactorial approach requires a unitive ‘mindbody’ model in which physical and subjective dimensions of personhood are seen as coexisting and equally deserving of exploration and management. Another influence is the tendency for ‘psychosomatic’ research studies in CSU to focus on patient experience using broad group-based diagnostic categories, such as anxiety and depressive disorders, and generic measures of stress. Two case examples are given, illustrating that CSU arises in relation to highly individual and relevant ‘stories’, which would not usually be picked up by these generic measures. It is suggested that an appropriate ‘mindbody’ management programme leading to good clinical outcomes for CSU is dependent on clinicians discerning unique patient ‘stories’. Finally, a lack of formal studies comparing drug and ‘mindbody’ treatment outcomes will continue to negatively influence the adoption of ‘mindbody’ approaches in CSU. There is an urgent need for properly structured comparative studies, and the essential elements of a suitable ‘mindbody’ approach appropriate to such research are briefly outlined.
Enhancing base-metal exploration with seismic imagingThis article is one of a series of papers published in this Special Issue on the themeLithoprobe — parameters, processes, and the evolution of a continent.
Authors: Eaton David W. , Adam Erick , Milkereit Bernd , Salisbury Matthew , Roberts Brian , White Don , Wright James
Published: June 2010

Commencing in 1988 and continuing for 5 years, Lithoprobe acquired a series of high-resolution seismic experiments within and near base-metal mining camps in Canada, including the Abitibi subprovince of Quebec and Ontario, the world-class Sudbury Ni–Cu mining district, the Buchans mine in Newfoundland, and the Thompson Ni belt in Manitoba. This work, undertaken in close cooperation with the Geological Survey of Canada and major Canadian mining companies, stimulated an intensive and broadened series of followup studies with the common objective of assessing potential applications of multichannel seismic (MCS) imaging for deep mineral exploration and mine development. This research was motivated by a widely recognized disparity between the depths from which ores can be profitably mined (up to 2 km or more) and the resolving depths (typically <500 m) of commonly used geophysical methods for mineral exploration. Initial rock-property studies established that the expected contrast in acoustic impedance between ores and host rocks should be sufficient to generate observable reflections and (or) scattered waves. For an ore deposit to be directly detectable with MCS, however, it is also necessary for it to meet geometrical criteria including a minimum thickness of 1/8 wavelenth (typically ∼5 m) and a lateral extent similar to the Fresnel radius (typically ∼100 m). Both Lithoprobe and followup seismic studies, calibrated with borehole data, reveal that lithologic contacts that are characterized by large impedance contrast and significant lateral continuity, such as igneous intrusive contacts between mafic and felsic rocks, are the most likely features to be imaged with the MCS techniques. In some camps such as Buchans, however, faults and shear zones are better imaged than lithologic contacts. In either case, these studies show that well-designed and carefully processed seismic profiles can provide a valuable geophysical tool for interpreting the stratigraphic and structural framework of mineral systems and, more rarely, direct-detection capabilities for deep ore deposits.
Mantle plume – volcanic arc interaction: consequences for magmatism, metallogeny, and cratonization in the Abitibi and Wawa subprovinces, CanadaThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.
Authors: Wyman Derek , Kerrich Robert
Published: June 2010

The Abitibi and Wawa subprovinces of the southern Superior Province differ in terms of the extent of pre-existing 2750 Ma sialic crust and relationships between mantle plume type (tholeiitic basalt – komatiite) and arc type (tholeiite to calc-alkaline basalt – andesite – dacite – rhyolite) volcanic successions but evolved in close proximity to each other. Isotopic data, evidence from the Kapuskasing uplift, continuation of major structures associated with large gold deposits from the Abitibi into the Wawa subprovince and the related occurrence of diamonds in lamprophyric rocks in both subprovinces point to a common evolution prior to and during orogeny. Differences preserved in supracrustal sequences of the two subprovinces suggest that the main petrogenetic controls on orogenic gold deposits and lamprophyre-hosted diamond deposits lay in the lower crust and upper mantle. Similar processes must also have been active where gold and diamonds are associated on other Archean cratons, such as the Slave and possibly the Kaapvaal craton. Based on evidence preserved in the Abitibi–Wawa orogen, rapid crustal growth at ∼2.7 Ga was linked to the interplay between plate tectonics and mantle plumes. Key indicators in the model developed for the Abitibi–Wawa arc are the co-existence of plume-related rock types, modern-style adakites, major gold deposits, and lamprophyre-hosted diamond occurrences, at least in cases where shoshonitic host magmas can ascend rapidly through the crust. All of these indicators are now identified on the Kaapvaal craton by 3.1 Ga and many recur together in Paleoproterzoic and younger terranes, suggesting a common mechanism for rapid crustal growth through much of Earth’s history. The variety of granitoid types found within the Abitibi–Wawa orogen demonstrates that local tectonic factors, rather than a hotter average upper mantle, were important in controlling the type of magmas formed. Based on the geodynamic history of the subprovince, mantle plume interaction with an existing volcanic arc and the subduction of oceanic plateau crust played an important role in the formation of magmas similar to Cenozoic adakites. Flat subduction beneath a mantle wedge was probably responsible for the generation of the adakites and also promoted diamond stability at shallow depths while enhancing the reservoirs for subsequent orogenic gold deposits. The history of magmatism and mineralization in the Abitibi and Wawa subprovinces precludes an early or gradual development of a cratonic keel, which instead must have coupled with crust during the latest stages of orogeny.
Protracted continental collision — evidence from the Grenville OrogenThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.
Authors: Hynes Andrew , Rivers Toby
Published: June 2010

The Grenville Orogen in North America is interpreted to have resulted from collision between Laurentia and another continent, probably Amazonia, at ca. 1100 Ma. The exposed segment of the orogen was derived largely from reworked Archean to Paleoproterozoic Laurentian crust, products of a long-lived Mesoproterozoic continental-margin arc and associated back arc, and remnants of one or more accreted mid-Mesoproterozoic island-arc terranes. A potential suture, preserved in Grenvillian inliers of the southeastern USA, may separate rocks of Laurentian and Amazonian affinities. The Grenvillian Orogeny lasted more than 100 million years. Much of the interior Grenville Province, with peak metamorphism at ca. 1090–1020 Ma, consists of uppermost amphibolite- to granulite-facies rocks metamorphosed at depths of ca. 30 km, but areas of lower crustal, eclogite-facies nappes metamorphosed at 50–60 km depth also occur and an orogenic lid that largely escaped Grenvillian metamorphism is preserved locally. Overall, deformation and regional metamorphism migrated sequentially to the northwest into the Laurentian craton, with the youngest contractional structures in the northwestern part of the orogen at ca. 1000–980 Ma. The North American lithospheric root extends across part of the Grenville Orogen, where it may have been produced by depletion of sub-continental lithospheric mantle beneath the long-lived Laurentian-margin Mesoproterozoic subduction zone. Both the Grenville Orogen and the Himalaya–Tibet Orogen have northern margins characterized by long-lived subduction before continental collision and protracted convergence following collision. Both exhibit cratonward-propagating thrusting. In the Himalaya–Tibet Orogen, however, the pre-collisional Eurasian-margin arc is high in the structural stack, whereas in the Grenville Orogen, the pre-collisional continental-margin arc is low in the structural stack. We interpret this difference as due to subduction reversal in the Grenville case shortly before collision, so that the continental-margin arc became the lower plate during the ensuing orogeny. The structurally low position of the warm, extended Laurentian crust probably contributed significantly to the ductility of lower and mid-crustal Grenvillian rocks.
The consequences of Canadian Cordillera thermal regime in recent tectonics and elevation: a reviewThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.Geological Survey of Canada Contribution 20090195.
Authors: Hyndman R. D.
Published: June 2010

The crust and upper mantle thermal regime of the Canadian Cordillera and its tectonic consequences were an important part of the Cordillera Lithoprobe program and related studies. This article provides a review, first of the thermal constraints, and then of consequences in high surface elevation and current tectonics. Cordillera and adjacent craton temperatures are well constrained by geothermal heat flow, mantle tomography velocities, upper mantle xenoliths, and the effective elastic thickness, Te. Cordillera temperatures are very high and laterally uniform, explained by small scale convection beneath a thin lithosphere, 800–900 °C at the Moho, contrasted to 400–500 °C for the craton. The high temperatures provide an explanation for why the Cordillera has high elevation in spite of a generally thin crust, ∼33 km, in contrast to low elevation and thicker crust, 40–45 km, for the craton. The Cordillera is supported ∼1600 m by lithosphere thermal expansion. In the Cordillera only the upper crust has significant strength; Te ∼ 15 km, in contrast to over 60 km for the craton. The Cordillera is tectonically active because the lithosphere is sufficiently weak to be deformed by plate boundary and gravitational forces; the craton is too strong. The Canadian Cordillera results have led to new understandings of processes in backarcs globally. High backarc temperatures and weak lithospheres explain the tectonic activity over long geological times of mobile belts that make up about 20% of continents. They also have led to a new understanding of collision orogenic heat in terms of incorporation of already hot backarcs.
AGE PROBLEM IN HOLOGRAPHIC DARK ENERGY
Authors: GRANDA L. N. , OLIVEROS A. , CARDONA W.
Published: June 2010

We study the age problem of the universe with the holographic dark energy (DE) model introduced in Ref. 37, and test the model with some known old high redshift objects (OHRO). The parameters of the model have been constrained using the SNIa, CMB and BAO data set. We found that the age of the old quasar APM 08 279+5255 at z = 3.91 can be described by the model.
DIBARYONS WITH STRANGENESS IN QUARK MODELS
Authors: CHEN MEI , GONG FANG , HUANG HONGXIA , PING JIALUN
Published: June 2010

The extended quark delocalization color screening model, which incorporates Goldstone–boson-exchange with soft cutoff, and chiral quark model are employed to do a systematic dynamical calculation of six-quark systems with strangeness. The two models give similar results, although they have different attraction mechanisms. Comparing with the previous calculation of the extended quark delocalization color screening model, in which the Goldstone–bosons are introduced with hard cutoff, the present calculation obtains a little large binding energies for most of the states. However, the conclusions are the same. The calculations show that NΩ state with IJ = 1/2, 2 is a good dibaryon candidate with narrow width, and ΩΩ state with IJ = 00 is a stable dibaryon against the strong interaction. The calculations also reveal several other possible dibaryon candidates with high angular momentum, ΔΣ*(1/2, 3), ΔΞ*(1, 3), etc. These states may have too wide width to be observed experimentally.
TYPICAL-MEDIUM THEORY OF MOTT–ANDERSON LOCALIZATION
Authors: Dobrosavljević V.
Published: June 2010

The Mott and the Anderson routes to localization have long been recognized as the two basic processes that can drive the metal–insulator transition (MIT). Theories separately describing each of these mechanisms were discussed long ago, but an accepted approach that can include both has remained elusive. The lack of any obvious static symmetry distinguishing the metal from the insulator poses another fundamental problem, since an appropriate static order parameter cannot be easily found. More recent work, however, has revisited the original arguments of Anderson and Mott, which stressed that the key diference between the metal end the insulator lies in the dynamics of the electron. This physical picture has suggested that the "typical" (geometrically averaged) escape rate [Formula: see text] from a given lattice site should be regarded as the proper dynamical order parameter for the MIT, one that can naturally describe both the Anderson and the Mott mechanism for localization. This article provides an overview of the recent results obtained from the corresponding Typical-Medium Theory, which provided new insight into the the two-fluid character of the Mott–Anderson transition.
TOPOLOGICAL PRINCIPLES IN THE THEORY OF ANDERSON LOCALIZATION
Authors: Pruisken A. M. M.
Published: June 2010

Scaling ideas in the theory of the quantum Hall effect are fundamentally based on topological principles in Anderson localization theory. These concepts have a very general significance and are not limited to replica field theory or disordered systems alone. In this chapter, we will discuss these ideas in several distinctly different physical contexts. We start with a brief overview that spans two and a half decades of experimental research on quantum criticality in strong magnetic fields. Secondly, we address the new understanding of universality that has emerged from the theory of Anderson localization and interaction phenomena. In the last part we show how the experimentally observed quantum phenomena fundamentally alter the way in which strong coupling problems in theoretical physics are perceived.
QUANTUM NETWORK MODELS AND CLASSICAL LOCALIZATION PROBLEMS
Authors: Cardy John
Published: June 2010

A review is given of quantum network models in class C which, on a suitable 2d lattice, describe the spin quantum Hall plateau transition. On a general class of graphs, however, many observables of such models can be mapped to those of a classical walk in a random environment, thus relating questions of quantum and classical localization. In many cases it is possible to make rigorous statements about the latter through the relation to associated percolation problems, in both two and three dimensions.