Fluid flow and heat transfer of natural convection at a slightly inclined,upward‐facing,heated plate

Natural convective flows over upward‐facing, inclined plates were investigated experimentally, with an emphasis on the role of opposing flows that appear over the plates inclined slightly from the horizontal line. The flow fields over the plates and the surface temperatures of the heated plates were visualized with both dye and a liquid‐crystal thermometry. The results showed that both the descending and ascending flows appeared over the plates when the inclination angles of the plates were less than 15°. The two flows collided with each other at a certain distance from the plate edge, and then detached from the plate to become a thermal plume. It was found that the above distance was determined solely by the inclination angles and was independent of sizes and heat fluxes of the plates. The local heat transfer coefficients of the plates were also measured. The results showed that the heat transfer from the plate was enhanced by the occurrence of the descending flows. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(5): 362–375, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10036     

Characterization of a new Bacillus subtilis peptidoglycan hydrolase gene, yvcE (named cwlO), and the enzymatic properties of its encoded protein

Bacillus subtilis yvcE (named cwlO) encodes a polypeptide consisting of 473 amino acid residues, and the N-terminal region contains a putative signal sequence and the C-terminal region exhibits high similarity to those of the NLPC/P60 superfamily (DL-endopeptidase family II). Northern blotting and cwlO-lacZ fusion analyses indicated that the cwlO gene is expressed as a monocistronic mRNA during the vegetative growth phase. The C-terminal region of CwlO was cloned into an Escherichia coli histidine-tagged vector and the protein, C-CwlO-6His, was produced in E. coli. The purified C-CwlO-6His protein exhibited cell wall hydrolase activity and the substrate bond specificity indicated that it is a DL-endopeptidase. The cell wall hydrolytic activity which seems to be derived from partially degraded CwlO (YvcE) was found in the culture supernatant of B. subtilis, but not in the cell wall binding fraction. The disruption of cwlO did not result in any difference in cell growth, morphology, or motility.     

Flame synthesis of graphene films in open environments

Few-layer graphene is grown on copper and nickel substrates at high rates using a novel flame synthesis method in open-atmosphere environments. Transmittance and resistance properties of the transferred films are similar to those grown by other methods, but the concentration of oxygen, as assessed by X-ray photoelectron spectroscopy, is actually less than that for graphene grown by chemical vapor deposition under near vacuum conditions. The method involves utilizing a multi-element inverse-diffusion-flame burner, where post-flame species and temperatures are radially-uniform upon deposition at a substrate. Advantages of the specific flame synthesis method are scalability for large-area surface coverage, increased growth rates, high purity and yield, continuous processing, and reduced costs due to efficient use of fuel as both heat source and reagent. Additionally, by adjusting local growth conditions, other carbon nanostructures (i.e. nanotubes) are readily synthesized.     

Estimating a change point in the long memory parameter

We propose an estimator of change point in the long memory parameter d of an ARFIMA(p, d, q) process using the sup Wald test. We derive the consistency and the rate of convergence of the estimator for the time of change. The convergence rate of our change point estimator depends on the magnitude of a shift. Furthermore, we obtain the limiting distribution of our change point estimator without depending on the distribution of the process. Therefore, we can construct confidence intervals for the change point. Simulations show the validity of the asymptotic theory of our estimator if the sample size is large enough. We apply our change point estimator to the yearly Nile river minimum water level.     

The POLARBEAR-2 Experiment

We present an overview of the design and development of the POLARBEAR-2 experiment. The POLARBEAR-2 experiment is a cosmic microwave background polarimetry experiment, which aims to characterize the small angular scale B-mode signal due to gravitational lensing and search for the large angular scale B-mode signal from inflationary gravitational waves. The experiment will have a 365 mm diameter multi-chroic focal plane filled with 7,588 polarization sensitive antenna-coupled Transition Edge Sensor bolometers and will observe at 95 and 150 GHz. The focal plane is cooled to 250 mK. The bolometers will be read-out by SQUIDs with \(32\times \) frequency domain multiplexing. The experiment will utilize high purity alumina lenses and thermal filters to achieve the required high optical throughput. A continuously rotating, cooled half-wave plate will be used to give stringent control over systematic errors. The experiment is designed to achieve a noise equivalent temperature of 5.7  \(\mu \) K \(\sqrt{s}\) , and this allows us to constrain the signal from the inflationary primordial gravitational corresponding to a tensor-to-scalar ratio of \(r = 0.01\) ( \(2\sigma \) ). POLARBEAR-2 will also be able to put a constraint on the sum of neutrino masses to 90 meV ( \(1\sigma \) ) with POLARBEAR-2 data alone and 65 meV ( \(1\sigma \) ) when combined with the Planck satellite. We plan to start observations in 2014 in the Atacama Desert in Chile.     

Hydrodynamic interaction between two red blood cells in simple shear flow: its impact on the rheology of a semi-dilute suspension

Blood is a suspension of red blood cells (RBCs) and its rheology is important when discussing the physiology of the cardiovascular system. In this study, we performed a numerical investigation of the rheological properties of an RBC suspension from the dilute to semi-dilute regime. RBCs were modelled as a capsule with a two-dimensional hyperelastic membrane. Large deformation of the thin membrane was calculated by a finite element method. Due to the small size of the RBC, fluid motion around the RBC was assumed to follow Stokes flow and was solved by a boundary element method. In the dilute limit, cell–cell interactions were omitted and the bulk stress of the suspension was calculated by the stresslet generated on a single RBC. Interestingly, the effective shear viscosity of the dilute suspension decreased with increasing viscosity of the internal liquid. In the semi-dilute regime, cells can be considered as showing pairwise interactions. The effective shear viscosity of the semi-dilute suspension shows a quadratic increase with respect to the volume fraction. These findings are important for understanding the complex phenomena of blood rheology.     

Overview of Advanced Spaceborne Thermal Emission and ReflectionRadiometer (ASTER)

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a research facility instrument provided by the Ministry of International Trade and Industry (MITI), Tokyo, Japan to be launched on NASA's Earth Observing System morning (EOS-AM1) platform in 1998. ASTER has three spectral hands in the visible near-infrared (VNIR), six bands in the shortwave infrared (SWIR), and five bands in the thermal infrared (TIR) regions, with 15-, 30-, and 90-m ground resolution, respectively. The VNIR subsystem has one backward-viewing band for stereoscopic observation in the along-track direction. Because the data will have wide spectral coverage and relatively high spatial resolution, it will be possible to discriminate a variety of surface materials and reduce problems in some lower resolution data resulting from mixed pixels. ASTER will, for the first time, provide high-spatial resolution multispectral thermal infrared data from orbit and the highest spatial resolution surface spectral reflectance temperature and emissivity data of all of the EOS-AM1 instruments. The primary science objective of the ASTER mission is to improve understanding of the local- and regional-scale processes occurring on or near the Earth's surface and lower atmosphere, including surface-atmosphere interactions. Specific areas of the science investigation include the following: (1) land surface climatology; (2) vegetation and ecosystem dynamics; (3) volcano monitoring; (4) hazard monitoring; (5) aerosols and clouds; (6) carbon cycling in the marine ecosystem; (7) hydrology; (8) geology and soil; and (9) land surface and land cover change. There are three categories of ASTER data: a global map, regional monitoring data sets, and local data sets to be obtained for requests from individual investigators     

Simulation and two-dimensional analytical modeling of subthresholdslope in ultrathin-film SOI MOSFETs down to 0.1 μm gate length

The subthreshold slope in ultra-thin-film fully depleted SOI MOSFETs is investigated for channel lengths from the long channel region down to 0.1 μm. A doping effect is found which allows improvement of the S-factor by increasing the channel doping concentration. In order to explain this phenomenon and to clarify the mechanism of S -factor degradation at short gate lengths, a two-dimensional analytical model is developed. A modified boundary condition for the two-dimensional Poisson equation is introduced to account for the nonlinear potential distribution inside the buried oxide. It is found that the S-factor short-channel degradation is governed by three mechanisms: the rise of capacitances at the channel source and drain ends due to the two-dimensional potentional distribution; the subthreshold current flow at the back channel surface; and the modulation of the effective current channel thickness during the gate voltage swing in the subthreshold region. The analytical model results are compared to those of numerical device simulation, and a good agreement is found