Critical values for unit root and cointegration test statistics - the use of response surface equations

This note considers the value of surface response equations which can be used to calculate critical values for a range of unit root and cointegration tests popular in applied economic research.

Simulation and optimization of heated, inviscid flows in scramjet ducts

A space-marching code for the simulation and optimization of inviscid supersonic flow in three dimensions is described. The now in a scramjet module with a relatively complex three-dimensional geometry is examined and wall-pressure estimates are compared with experimental data. Given that viscous effects are not presently included, the comparison is reasonable. The thermodynamic compromise of adding heat in a diverging combustor is also examined. The code is then used to optimize the shape of a thrust surface for a simpler (box-section) scramjet module in the presence of uniform and nonuniform heat distributions. The optimum two-dimensional profiles for the thrust surface are obtained via a perturbation procedure that requires about 30-50 now solutions. It is found that the final shapes are fairly insensitive to the details of the heat distribution.

Effects of medium thermoelasticity on high Rayleigh number steady-state heat transfer and mineralization in deformable fluid-saturated porous media heated from below

In this paper, a solution method is presented to deal with fully coupled problems between medium deformation, pore-fluid flow and heat transfer in fluid-saturated porous media having supercritical Rayleigh numbers. To validate the present solution method, analytical solutions to a benchmark problem are derived for some special cases. After the solution method is validated, a numerical study is carried out to investigate the effects of medium thermoelasticity on high Rayleigh number steady-state heat transfer and mineralization in fluid-saturated media when they are heated from below. The related numerical results have demonstrated that: (1) medium thermoelasticity has a little influence on the overall pattern of convective pore-fluid flow, but it has a considerable effect on the localization of medium deformation, pore-fluid flow, heat transfer and mineralization in a porous medium, especially when the porous medium is comprised of soft rock masses; (2) convective pore-fluid flow plays a very important role in the localization of medium deformation, heat transfer and mineralization in a porous medium. (C) 1999 Elsevier Science S.A. All rights reserved.

Turn up the HEAT

The recently determined crystal structure of the PR65/A subunit of protein phosphatase 2A reveals the architecture of proteins containing HEAT repeats, The structural properties of this solenoid protein explain many functional characteristics and account for the involvement of solenoids as scaffold, anchoring and adaptor proteins.

Whole-body pre-cooling and heat storage during self-paced cycling performance in warm humid conditions

The aim of this study was to establish the effect that pre-cooling the skin without a concomitant reduction in core temperature has on subsequent self-paced cycling performance under warm humid (31 degrees C and 60% relative humidity) conditions. Seven moderately trained males performed a 30 min self-paced cycling trial on two separate occasions. The conditions were counterbalanced as control or whole-body pre-cooling by water immersion so that resting skin temperature was reduced by approximate to 5-6 degrees C. After pre-cooling, mean skin temperature was lower throughout exercise and rectal temperature was lower (P < 0.05) between 15 and 25 min of exercise. Consequently, heat storage increased (P < 0.003) from 84.0 +/- 8.8 W . m(-2) to 153 +/- 13.1 W . m(-2) (mean +/- s((x) over bar)) after pre-cooling, while total body sweat fell from 1.7 +/- 0.1 1 . h(-1) to 1.2 +/- 0.1 1 . h(-1) (P < 0.05). The distance cycled increased from 14.9 +/- 0.8 to 15.8 +/- 0.7 km (P < 0.05) after pre-cooling. The results indicate that skin pre-cooling in the absence of a reduced rectal temperature is effective in reducing thermal strain and increasing the distance cycled in 30 min under warm humid conditions.

Changes in quantum efficiency of Photosystem II of symbiotic dinoflagellates of corals after heat stress, and of bleached corals sampled after the 1998 Great Barrier Reef mass bleaching event Ross J. Jones , Selina Ward, Affendi Yang Amri and Ove Hoegh-Guldberg

Pulse-amplitude-modulation chlorophyll fluorometry was used to examine changes in dark-adapted F-v/F-m of endosymbiotic dinoflagellate microalgae within the tissues of the temperate coral Plesiastrea versipora exposed to elevated seawater temperature. The F-v/F-m was markedly reduced following exposure of corals to 28 degrees C for 48 h. When corals were returned to ambient (24 degrees C) conditions, F-v/F-m increased in an initial rapid and then secondary slower phase. Tissue discolouration (coral bleaching), caused by a significant decrease in the density of algae, was observed during the first 2-3 days of the recovery period. After 14 days, F-v/F-m was still significantly lower than in control corals. The recovery of F-v/F-m is discussed in terms of repair processes within the symbiotic algae, division of healthy algae and also the selective removal of photo-damaged dinoflagellates. Under field conditions, bleached corals sampled at Heron Island Reef during a bleaching event had significantly lower F-v/F-m than non-bleached colonies; four months after the bleaching event, there were no differences in F-v/F-m or algal density in corals marked as having bleached or having shown no signs of colour loss. The results of this laboratory and field study are consistent with the hypothesis that an impairment of photosynthesis occurs during heat-stress, and is the underlying cause of coral bleaching.

Finite element analysis of heat transfer and mineralization in layered hydrothermal systems with upward throughflow

We use the finite element method to solve the coupled problem between convective pore-fluid flow, heat transfer and mineralization in layered hydrothermal systems with upward throughflow. In particular, we present the improved rock alteration index (IRAI) concept for predicting the most probable precipitation and dissolution regions of gold (Au) minerals in the systems. To validate the numerical method used in the computation, analytical solutions to a benchmark problem have been derived. After the numerical method is validated, it is used to investigate the pattern of pore-fluid Aom, the distribution of temperature and the mineralization pattern of gold minerals in a layered hydrothermal system with upward throughflow. The related numerical results have demonstrated that the present concept of IRAI is useful and applicable for predicting the most probable precipitation and dissolution regions of gold (Au) minerals in hydrothermal systems. (C) 2000 Elsevier Science S.A. All rights reserved.

Finite element modeling of fluid-rock interaction problems in pore-fluid saturated hydrothermal/sedimentary basins

In order to use the finite element method for solving fluid-rock interaction problems in pore-fluid saturated hydrothermal/sedimentary basins effectively and efficiently, we have presented, in this paper, the new concept and numerical algorithms to deal with the fundamental issues associated with the fluid-rock interaction problems. These fundamental issues are often overlooked by some purely numerical modelers. (1) Since the fluid-rock interaction problem involves heterogeneous chemical reactions between reactive aqueous chemical species in the pore-fluid and solid minerals in the rock masses, it is necessary to develop the new concept of the generalized concentration of a solid mineral, so that two types of reactive mass transport equations, namely, the conventional mass transport equation for the aqueous chemical species in the pore-fluid and the degenerated mass transport equation for the solid minerals in the rock mass, can be solved simultaneously in computation. (2) Since the reaction area between the pore-fluid and mineral surfaces is basically a function of the generalized concentration of the solid mineral, there is a definite need to appropriately consider the dependence of the dissolution rate of a dissolving mineral on its generalized concentration in the numerical analysis. (3) Considering the direct consequence of the porosity evolution with time in the transient analysis of fluid-rock interaction problems; we have proposed the term splitting algorithm and the concept of the equivalent source/sink terms in mass transport equations so that the problem of variable mesh Peclet number and Courant number has been successfully converted into the problem of constant mesh Peclet and Courant numbers. The numerical results from an application example have demonstrated the usefulness of the proposed concepts and the robustness of the proposed numerical algorithms in dealing with fluid-rock interaction problems in pore-fluid saturated hydrothermal/sedimentary basins. (C) 2001 Elsevier Science B.V. All rights reserved.

Human cyclophilin 40 is a heat shock protein that exhibits altered intracellular localization following heat shock

The unactivated steroid receptors are chaperoned into a conformation that is optimal for binding hormone by a number of heat shock proteins, including Hsp90, Hsp70, Hsp40, and the immunophilin, FKBP52 (Hsp56). Together with its partner cochaperones, cyclophilin 40 (CyP40) and FKBP51, FKBP52 belongs to a distinct group of structurally related immunophilins that modulate steroid receptor function through their association with Hsp90. Due to the structural similarity between the component immunophilins, FKBP52 and cyclophilin 40, we decided to investigate whether CyP40 is also a heat shock protein. Exposure of MCF-7 breast cancer cells to elevated temperatures (42 degreesC for 3 hours) resulted in a 75-fold increase in CyP40 mRNA levels, but no corresponding increase in CyP40 protein expression, even after 7 hours of heat stress. The use of cycloheximide to inhibit protein synthesis revealed that in comparison to MCF-7 cells cultured at 37 degreesC, those exposed to heat stress (42 degreesC for 3 hours) displayed an elevated rate of degradation of both CyP40 and FKBP52 proteins. Concomitantly, the half-life of the CyP40 protein was reduced from more than 24 hours to just over 8 hours following heat shock. As no alteration in CyP40 protein levels occurred in cells exposed to heat shock, an elevated rate of degradation would imply that CyP40 protein was synthesized at an increased rate. hence the designation of human CyP40 as a heat shock protein. Application of heat stress elicited a marked redistribution of CyP40 protein in MCF-7 cells from a predominantly nucleolar localization, with some nuclear and cytoplasmic staining, to a pattern characterized by a pronounced nuclear accumulation of CyP40, with no distinguishable nucleolar staining. This increase in nuclear CyP40 possibly resulted from a redistribution of cytoplasmic and nucleolar CyP40, as no net increase in CyP40 expression levels occurred in response to stress. Exposure of MCF-7 cells to actinomycin D for 4 hours resulted in the translocation of the nucleolar marker protein, B23, from the nucleolus, with only a small reduction in nucleolar CyP40 levels. Under normal growth conditions, MCF-7 cells exhibited an apparent colocalization of CyP40 and FKBP52 within the nucleolus.

Finite element modelling of heat transfer through permeable cracks in hydrothermal systems with upward throughflow

We use the finite element method to model the heat transfer phenomenon through permeable cracks in hydrothermal systems with upward throughflow. Since the finite element method is an approximate numerical method, the method must be validated before it is used to soh,e any new, kind of problem. However, the analytical solution, which can be used to validate the finite element method and other numerical methods, is rather limited in the literature, especially, for the problem considered here. Keeping this in mind, we have derived analytical solutions for the temperature distribution along the vertical axis of a crack in a fluid-saturated porous layer. After the finite element method is validated by comparing the numerical solution with the analytical solution for the same benchmark problem, it is used to investigate the pore-fluid flow and heat transfer in layered hydrothermal systems with vertical permeable cracks. The related analytical and numerical results have demonstrated that vertical cracks are effective and efficient members to transfer heat energy from the bottom section to the top section in hydrothermal systems with upward throughflow.

Phase and microstructural evolution during the heat treatment of Sm-Ca-alpha-sialon ceramics

The phase and microstructural evolution of multi-cation Sm-Ca-alpha-sialon ceramics was investigated. Six samples were prepared, ranging from a pure Sm-sialon to a pure Ca-sialon, with calcium replacing samarium in 20 eq% increments, thus maintaining an equivalent design composition in all samples. After pressureless sintering at 1820 degreesC for 2 It, all samples were subsequently heat treated up to 192 h at 1450 and 1300 degreesC. The amount of grain boundary glass in the samples after sintering was observed to decrease with increasing calcium levels. A M-ss' or M-ss',-gehlenite solid solution was observed to form during the 1450 degreesC heat treatment of all Sm-containing samples, and this phase forms in clusters in the high-Sm samples. The thermal stability of the alpha-sialon phase was improved in the multi-cation systems. Heat treatment at 1300 degreesC produces SmAlO3 in the high-Sm samples, a M-ss',-gehlenite solid solution in the high-Ca samples, and a Sm-Ca-apatite phase in some intermediate samples. (C) 2002 Elsevier Science Ltd. All rights reserved.

Analysis of steady-state heat transfer through mid-crustal vertical cracks with upward throughflow in hydrothermal systems

We conduct a theoretical analysis of steady-state heat transfer problems through mid-crustal vertical cracks with upward throughflow in hydrothermal systems. In particular, we derive analytical solutions for both the far field and near field of the system. In order to investigate the contribution of the forced advection to the total temperature of the system, two concepts, namely the critical Peclet number and the critical permeability of the system, have been presented and discussed in this paper. The analytical solution for the far field of the system indicates that if the pore-fluid pressure gradient in the crust is lithostatic, the critical permeability of the system can be used to determine whether or not the contribution of the forced advection to the total temperature of the system is negligible. Otherwise, the critical Peclet number should be used. For a crust of moderate thickness, the critical permeability is of the order of magnitude of 10(-20) m(2), under which heat conduction is the overwhelming mechanism to transfer heat energy, even though the pore-fluid pressure gradient in the crust is lithostatic. Furthermore, the lower bound analytical solution for the near field of the system demonstrates that the permeable vertical cracks in the middle crust can efficiently transfer heat energy from the lower crust to the upper crust of the Earth. Copyright (C) 2002 John Wiley Sons, Ltd.

Polydnavirus particle proteins with similarities to molecular chaperones, heat-shock protein 70 and calreticulin

Multipartite nucleic acid-containing virus-like particles, known as polydnaviruses, are special structures produced by female parasitoid wasps to deliver wasp components into the body of their host at oviposition. The particles confer protection for the developing parasitoid by passive and active means. Although several genes expressed from the circular DNA of these particles have been identified from various host-parasitoid systems, there is not much known about the structural proteins of these particles. Here we report on two genes encoding Cotesia rubecula particle proteins with similarities to molecular chaperones, calreticulin and heat-shock protein 70.

Effects of hot intrusions on pore-fluid flow and heat transfer in fluid-saturated rocks

We use the finite element method to solve coupled problems between pore-fluid flow and heat transfer in fluid-saturated porous rocks. In particular, we investigate the effects of both the hot pluton intrusion and topographically driven horizontal flow on the distributions of the pore-flow velocity and temperature in large-scale hydrothermal systems. Since general mineralization patterns are strongly dependent on distributions of both the pore-fluid velocity and temperature fields, the modern mineralization theory has been used to predict the general mineralization patterns in several realistic hydrothermal systems. The related numerical results have demonstrated that: (1) The existence of a hot intrusion can cause an increase in the maximum value of the pore-fluid velocity in the hydrothermal system. (2) The permeability of an intruded pluton is one of the sensitive parameters to control the pore-fluid flow, heat transfer and ore body formation in hydrothermal systems. (3) The maximum value of the pore-fluid velocity increases when the bottom temperature of the hydrothermal system is increased. (4) The topographically driven flow has significant effects on the pore-fluid flow, temperature distribution and precipitation pattern of minerals in hydrothermal systems. (5) The size of the computational domain may have some effects on the pore-fluid flow and heat transfer, indicating that the size of a hydrothermal system may affect the pore-fluid flow and heat transfer within the system. (C) 2003 Elsevier Science B.V. All rights reserved.