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Plane thermal transpiration of a slightly rarefied gas that flows horizontally in the presence of weak gravitation is studied based on the fluid-dynamic-type equation and the slip-type boundary condition derived from the Boltzmann equation. We consider the situation where the Knudsen number (the mean free path divided by the channel width) is small and the dimensionless gravity (the channel width divided by the ascent height of the molecules against gravity) is of the order of the square of the Knudsen number. The fluid-dynamic equation is studied by the asymptotic analysis for the slow variation in the longitudinal direction, and the nontrivial leading order solution is obtained analytically. Due to the combination of gravity and the temperature gradient imposed along the channel, a pressure gradient is produced in both the vertical and the horizontal directions. The horizontal pressure gradient induces the flow even in the absence of the gradient of the sectionally averaged pressure. Although the pressure gradient produced is of the higher order of the Knudsen number, the flow induced by the gradient is of the order of the Knudsen number and thus has a relatively finite effect on the thermal transpiration. The velocity profile is considerably different from that of the conventional thermal transpiration due to the effect of weak gravitation. A direct numerical analysis of a flow through a long channel is conducted based on the model Boltzmann equation, and the mechanism of this phenomenon is demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: In order to understand the effect of the wall permeability on the turbulent vortex structure near porous walls, based on PIV experimental data, a probability density analysis of fluctuating velocities, statistical quadrant and quadrant-hole analyses of the Reynolds shear stress are performed. The investigated flow fields are turbulent channel flows whose bottom walls are made of porous media. The porous media used are three kinds of foamed ceramics which have almost the same porosity (∼0.8) but different permeability. From the discussions on those analyses, a conceptual scenario of the development of the vortex structure near a permeable wall is proposed for a moderate permeability Reynolds number case. It explains the reason why the near-wall long streaky structure tends to vanish near a porous wall with increasing wall permeability. [Copyright &y& Elsevier]

Abstract: In order to understand the effects of the wall permeability on turbulence near a porous wall, flow field measurements are carried out for turbulent flows in a channel with a porous bottom wall by a two-component particle image velocimetry (PIV) system. The porous media used are three kinds of foamed ceramics which have almost the same porosity (∼0.8) but different permeability. It is confirmed that the flow becomes more turbulent over the porous wall and tends to be turbulent even at the bulk Reynolds number of in the most permeable wall case tested. Corresponding to laminar to turbulent transition, the magnitude of the slip velocity on the porous wall is found to increase drastically in a narrow range of the Reynolds number. To discuss the effects of the wall roughness and the wall permeability, detailed discussions are made of zero-plane displacement and equivalent wall roughness for porous media. The results clearly indicate that the turbulence is induced by not only the wall roughness but the wall permeability. The measurements have also revealed that as or the wall permeability increases, the wall normal fluctuating velocity near the porous wall is enhanced due to the effects of the wall permeability. This leads to the increase of the turbulent shear stress resulting in higher friction factors of turbulence over porous walls. [ABSTRACT FROM AUTHOR]

Abstract: In order to provide a practical strategy for solving mass transfer fields across air–water interfaces, an extended version of the analytical wall-function (AWF) is presented. (This wall-function is designed for Reynolds averaged Navier Stokes simulations.) By considering exact near-surface limiting profiles of turbulence quantities such as the eddy viscosity and the turbulent scalar flux, the prescribed turbulent diffusivity profile, which is a core assumption of the AWF, is modelled to have the correct limiting behaviour. The resultant AWF performs well to predict surface mass transfer rates and turbulent concentration fields across undeformable air–water interfaces at Schmidt numbers of 1⩽ Sc ⩽1000. [Copyright &y& Elsevier]

Purpose: Tc-99m-Technegas-MAA single photon emission computed tomography (SPECT)-derived ventilation (V)/perfusion (Q) quotient SPECT was used to assess lung V-Q imbalance in patients with pulmonary emphysema. Methods: V/Q quotient SPECT and V/Q profile were automatically built in 38 patients with pulmonary emphysema and 12 controls, and V/Q distribution and V/Q profile parameters were compared. V/Q distribution on V/Q quotient SPECT was correlated with low attenuation areas (LAA) on density-mask computed tomography (CT). Parameters of V/Q profile such as the median, standard deviation (SD), kurtosis and skewness were proposed to objectively evaluate the severity of lung V-Q imbalance. Results: In contrast to uniform V/Q distribution on V/Q quotient SPECT and a sharp peak with symmetrical V/Q distribution on V/Q profile in controls, lung areas showing heterogeneously high or low V/Q and flattened peaks with broadened V/Q distribution were frequently seen in patients with emphysema, including lung areas with only slight LAA. V/Q distribution was also often asymmetric regardless of symmetric LAA. All the proposed parameters of V/Q profile in entire lungs of patients with emphysema showed large variations compared with controls; SD and kurtosis were significantly different from controls (P < 0.0001 and P < 0.001, respectively), and a significant correlation was found between SD and A-aDO2 (P < 0.0001). Conclusions: V/Q quotient SPECT appears to be more sensitive to detect emphysematous lungs compared with morphologic CT in patients with emphysema. SD and kurtosis of V/Q profile can be adequate parameters to assess the severity of lung V-Q imbalance causing gas-exchange impairment in patients with emphysema. [ABSTRACT FROM AUTHOR]

We performed high-field magnetization measurements, M( H), on the Ni5(TeO3)4Br2 by using a pulse magnet. The Ni2+ ions ( S = 1) of this compound form a two dimensional distorted spin frustrated system (distorted kagome lattice), and undergo a Neel transition at T N∼29 K, due to the anisotropy. Below T N, a complex spin arrangement which contains ten spin sub-lattices was suggested by neutron scattering and electron spin resonance studies. We observed a step-like transition at H c∼11 T when T< T N. By contrast, at T> T N, the field-dependent magnetization curves behaved like a straight line. The H c is close to those obtained by previous spin resonance studies of Ni5(TeO3)4Br2 and Ni5(TeO3)4Cl2 in which a spin-flop-like transition was proposed to explain the field-dependent resonance spectra. Interestingly, the observed change in magnetization (Δ M) at H c corresponds to nearly one-half of the magnetic moment of Ni2+ ion, suggesting that the observed step-like behavior possibly corresponds to a spin-flip-like transition (i.e. from antiferromagnetic state to ferrimagnetic state). In addition, in the high-field region ( H> H c), the M( H) curves did not show plateau behavior, but exhibited the straight lines having finite slopes without any sign of saturation up to 55 T. [ABSTRACT FROM AUTHOR]

We performed high-field magnetization measurements, M( H), on the Ni5(TeO3)4Br2 by using a pulse magnet. The Ni2+ ions ( S = 1) of this compound form a two dimensional distorted spin frustrated system (distorted kagome lattice), and undergo a Neel transition at T N∼29 K, due to the anisotropy. Below T N, a complex spin arrangement which contains ten spin sub-lattices was suggested by neutron scattering and electron spin resonance studies. We observed a step-like transition at H c∼11 T when T< T N. By contrast, at T> T N, the field-dependent magnetization curves behaved like a straight line. The H c is close to those obtained by previous spin resonance studies of Ni5(TeO3)4Br2 and Ni5(TeO3)4Cl2 in which a spin-flop-like transition was proposed to explain the field-dependent resonance spectra. Interestingly, the observed change in magnetization (Δ M) at H c corresponds to nearly one-half of the magnetic moment of Ni2+ ion, suggesting that the observed step-like behavior possibly corresponds to a spin-flip-like transition (i.e. from antiferromagnetic state to ferrimagnetic state). In addition, in the high-field region ( H> H c), the M( H) curves did not show plateau behavior, but exhibited the straight lines having finite slopes without any sign of saturation up to 55 T. [ABSTRACT FROM AUTHOR]

Abstract: We have measured a pulsed laser induced transient Nernst-Ettingshausen (TNE) effect for semimetal Bi and for nearly gapless materials Bi-Sb and Bi-Te alloy single crystals at 4.2 K and under magnetic fields up to 4 T. We have found the giant longitudinal-TNE (-TNE) and transverse-TNE (-TNE) signals for all materials. The -TNE signals show a quite unusual antisymmetric magnetic field dependence, which suggests a mechanism of bipolar state caused by breakdown of space inversion symmetry. [Copyright &y& Elsevier]

Abstract: We have measured magnetoresistance (MR) for semimetals Bi and graphite, nearly gapless materials Bi-Sb and Bi-Te alloys, and narrow gap semiconductor Ag2Se single crystals at 4.2 K and up to 4 T. We have observed a giant MR for Bi, a giant linear MR (LMR) for Bi-Sb alloy and Ag2Se single crystals. Anomalous completely linear weak-field LMR has been found for nearly gapless materials: this is transferred into the ordinal MR or other LMR in relatively strong field range. It suggests the linear band dispersion in nearly gapless materials as proposed by Abrikosov. [Copyright &y& Elsevier]

Objective: To clarify the difference of (18)F-FDG uptake kinetics between FDG-avid metastatic lymph nodes (LNs) in patients with non-small-cell lung cancer (NSCLC) and FDG-avid benign LNs associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation. Methods: The subjects were 134 FDG-avid metastatic LNs in 67 patients with NSCLC and 62 FDG-avid benign LNs in 61 patients with various lung disorders including NSCLC. PET/CT scan was performed at 2 time points (at 60 min and at 120 min) after intravenous injection of 4.4 MBq/kg (18)F-FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) were measured at each FDG-avid LN. The optimal parameter for differentiation was determined by the receiver-operating characteristic analysis. Results: Delayed SUVmax was increased compared with early SUVmax in 114 (85.0%) FDG-avid metastatic LNs and 42 (67.7%) FDG-avid benign LNs, with significant higher delayed SUVmax than early values (7.0 +/- 5.0 vs. 5.9 +/- 3.4; P < 0.0001, and 3.0 +/- 1.3 vs. 2.8 +/- 1.0; P < 0.05, respectively). Early and delayed SUVmax and %DeltaSUVmax in metastatic LNs were significantly higher than those in benign LNs (P < 0.0001). The optimal parameter for the differentiation was the combined use of early SUVmax > 3.0 or delayed SUVmax > 4.0, yielding sensitivity of 88.8%, specificity of 80.6%, accuracy of 86.2%, negative predictive value of 76.9%, and positive predictive value of 90.6%. It provided better results than the use of early SUVmax > 3.0 alone (P = 0.019) or the optimal parameter for %DeltaSUVmax (>5%) (P = 0.012). However, 12 (19.3%) benign LNs were indistinguishable from metastatic LNs. Conclusions: Although dual-time point PET/CT scan enhances the difference of FDG uptake between FDG-avid metastatic and benign LNs and improves the differentiation when compared with a single scan, biopsy procedure may be still required for accurate assessment of LN status in patients with NSCLC and possible etiologies showing intensive FDG uptake in benign LNs. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study is to clarify the difference of F-18 FDG uptake kinetics between FDG-avid non-small-cell lung cancer (NSCLC) and benign lesions associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation. Materials and Methods: The materials were 76 FDG-avid solitary NSCLC in 76 patients and 57 FDG-avid solitary benign lesions associated with various etiologies in 61 patients. FDG PET/CT scan was performed at 60 and 120 min after intravenous injection of 4.4 MBq/kg F-18 FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis and evaluation of diagnostic accuracy. Results: The mean +/- SD of early SUV max, delayed SUVmax and %DeltaSUVmax were 8.3 +/- 5.2, and 10.2 +/- 6.5, and 21.9% +/- 18.9 in FDG-avid NSCLC, and 3.8 +/- 3.2, 4.0 +/- 3.7, and 11.3% +/- 26.0 in FDG-avid benign lesions, respectively. Delayed SUVmax in NSCLC was significantly higher than early SUVmax (P < 0.0001); while not different in benign lesions. Percent change of SUVmax in NSCLC was also significantly higher than that in benign lesions (P < 0.01). The optimal parameter for the differentiation was delayed SUVmax > 5.5 and yielded sensitivity of 77.6%, specificity of 80.7% and accuracy of 78.9%, which provided better differentiation than the use of %DeltaSUVmax or the traditional parameter of early SUVmax > 2.5. However, 11 (19.2%) benign lesions were indistinguishable from NSCLC. Conclusion: Although delayed PET/CT scan enhances the difference of FDG uptake between FDG-avid NSCLC and benign lesions, and the use of delayed SUVmax > 5.5 appears to improve the differentiation of these hypermetabolic lesions compared with an early scan, careful interpretation and management for correct differentiation are still required. [ABSTRACT FROM AUTHOR]

Background: The functional mechanism of lung mosaic computed tomography attenuation (MCA) in pulmonary vascular disease (PVD) and obstructive airway disease (OAD) has not yet been fully clarified. Purpose: To clarify the mechanism of MCA in these diseases by assessing the relationship between regional lung function and CT attenuation change at MCA sites with the use of automated deep-inspiratory breath-hold (DIBrH) perfusion single-photon emission computed tomography (SPECT)-CT fusion images and non-breath-hold Technegas SPECT. Material and Methods: Subjects were 42 PVD patients (31 pulmonary thromboembolism, four primary/two secondary pulmonary hypertension, and five Takayasu arteritis), 12 OAD patients (five acute asthma, four obliterative bronchiolitis, and three bronchiectasis), and 12 normal controls, all of whom had MCA on DIBrH CT. The relationship between regional lung function and CT attenuation change at the lung slices with MCA was assessed using DIBrH perfusion SPECT-CT fusion images and non-breath-hold Technegas SPECT. The severity of perfusion defects with or without MCA was quantified by regions-of-interest analysis. Results: On DIBrH CT and perfusion SPECT, in contrast to no noticeable CT attenuation abnormality and fairly uniform perfusion in controls, 60 MCA and 274 perfusion defects in PVD patients, and 18 MCA and 61 defects in OAD patients were identified, with a total of 77 ventilation defects on Technegas SPECT in all patients. SPECT-CT correlation showed that, throughout the 78 MCA sites of all patients, lung perfusion was persistently decreased at low CT attenuation and preserved at intervening high CT attenuation, while lung ventilation was poorly correlated with CT attenuation change. The radioactivity ratios of reduced perfusion and the intervening preserved perfusion at the 78 perfusion defects with MCA were significantly lower than those at the remaining 257 defects without MCA (P<0.0001). Conclusion: Although further validation is required, our results indicate that heterogeneous pulmonary arterial perfusion may be a dominant mechanism of MCA in PVD and OAD. [ABSTRACT FROM AUTHOR]