bluuebunny/crossref_metadata_2025 huggingface dataset:
The Misinterpretation of Women's Status in the Muslim World
Authors: Al‐Mannai Salah S.
Published: May 2010

Spiritual equality, responsibility, and accountability for both men and women are well‐developed themes in the Qur'an. Spiritual equality between men and women in the sight of God is not limited purely to religious issues, but is the basis for equality in all aspects of human endeavor. This article's main interest is in the woman's status, and her role within the Arab countries. Islam is the main religion—its principles, values, and practices are dominant in the region. Therefore, this article introduces and discusses the misinterpretation of women in Islam, with special consideration of Muslim women's rights and their roles within the Muslim society. This will help to enhance future discussions of social behavior, values, and attitudes toward women in Islam.

In the last few decades there has been a great misunderstanding in many aspects of public consciousness about the role of women in Arabic society. There is a significant gap between the status of males and females. However, this gap is more evident in rural areas. The level of women's rights and roles in many Arabic countries prevents women from improving their economic growth and development. This gender gap is the result of social, religious, cultural, and gender inequality. More specifically, it results from structural constraints faced by women.

Gender inequality is not a new issue, nor is it only Muslim women who are suffering from this inequality. There is gender discrimination almost everywhere.

The Qur'an is the basis of Islam, and encompasses rules, legislation, examples, advice, history, and system of the universe. It draws a picture of the earth and describes the roles of human beings. The Qur'an is the answer to the spiritual and material needs of the Islamic society, and is an exposition and an explanation of all aspects of life.
On reducibility and ergodicity of population projection matrix models
Authors: Stott Iain , Townley Stuart , Carslake David , Hodgson David J.
Published: May 2010

1. Population projection matrices (PPMs) are probably the most commonly used empirical population models. To be useful for predictive or prospective analyses, PPM models should generally be irreducible (the associated life cycle graph contains the necessary transition rates to facilitate pathways from all stages to all other stages) and therefore ergodic (whatever initial stage structure is used in the population projection, it will always exhibit the same stable asymptotic growth rate).

2. Evaluation of 652 PPM models for 171 species from the literature suggests that 24·7% of PPM models are reducible (parameterized transition rates do not facilitate pathways from all stages to all other stages). Reducible models are sometimes ergodic but may be non‐ergodic (the model exhibits two or more stable asymptotic states with different asymptotic stable growth rates, which depend on the initial stage structure used in the population projection). In our sample of published PPMs, 15·6% are non‐ergodic.

3. This presents a problem: reducible–ergodic models often defy biological rationale in their description of the life cycle but may or may not prove problematic for analysis as they often behave similarly to irreducible models. Reducible–non‐ergodic models will usually defy biological rationale in their description of the both the life cycle and population dynamics, hence contravening most analytical methods.

4. We provide simple methods to evaluate reducibility and ergodicity of PPM models, present illustrative examples to elucidate the relationship between reducibility and ergodicity and provide empirical examples to evaluate the implications of these properties in PPM models.

5. As a prevailing tool for population ecologists, PPM models need to be as predictive as possible. However, there is a large incidence of reducibility in published PPMs, with significant implications for the predictive power of such models in many cases. We suggest that as a general rule, reducibility of PPM models should be avoided. However, we provide a guide to the pertinent analysis of reducible matrix models, largely based upon whether they are ergodic or not.
Flow and Dipole Source Evaluation of a Generic SUV
Authors: Ask Jonas , Davidson Lars
Published: May 2010

Accurately predicting both average flow quantities and acoustic sources at the front window of today’s ground vehicles are still a considerable challenge to automotive companies worldwide. One of the most important aspects in terms of obtaining not only trustworthy results but also the most tedious one and therefore perhaps overlooked, is the control and outcome of the mesh generation process. Generating unstructured volume meshes suitable for large eddy simulations with high level representation of geometrical details is both a time consuming and an extremely computer demanding activity. This work investigates two different mesh generation processes with its main aim to evaluate their outcome with respect to the prediction of the two dominating dipole sources in a temporal form of the Curle’s equation. Only a handful of papers exists that report a high level representation of the vehicle geometry and the aim of predicting the fluctuating exterior noise sources. To the author’s knowledge no studies have been conducted in which both these source terms are evaluated quantitatively against measurements. The current paper investigates the degree to which the amplitude of these two source terms can be predicted by using the traditional law-of-the-wall and hex-dominant meshes with isotropic resolution boxes for a detailed ground vehicle geometry. For this purpose, the unstructured segregated commercial FLUENT finite volume method code is used. The flow field is treated as incompressible and the Smagorinsky–Lilly model is used to compute the subgrid stresses. Mean flow quantities are measured with a 14 hole probe for 14 rakes downstream of the side mirror. The dynamic pressure sensors are distributed at 16 different positions over the side window to capture the fluctuating pressure signals. All measurements in this work were conducted at Ford’s acoustic wind tunnel in Cologne. All three simulations accurately predict the velocity magnitude closest to the window and downstream of the mirror head recirculation zone. Some variations in the size and shape of this recirculation zone are found between the different meshes, most probably caused by differences in the detachment of the mirror head boundary layer. The Strouhal number of the shortest simulation was computed from the fundamental frequency of the drag force coefficient. The computed Strouhal number agrees well with the corresponding results from similar objects and gives an indication of an acceptable simulation time. The dynamic pressure sensors at 16 different locations at the vehicle side window were also used to capture the levels of the two dipole source terms. These results are compared with the three simulations. With the exception of three positions, at least one of the three simulations accurately captures the levels of both source terms up to about 1000 Hz. The three positions with less agreement as compared with measurements were found to be in regions sensitive to small changes in the local flow direction.
Shape Optimization of a Multi-Element Foil Using an Evolutionary Algorithm
Authors: Lee Yu-Tai , Ahuja Vineet , Hosangadi Ashvin , Ebert Michael
Published: May 2010

A movable flap with a NACA foil cross section serves as a common control surface for underwater marine vehicles. To augment the functionality of the control surface, a tab assisted control (TAC) surface was experimentally tested to improve its performance especially at large angles of operation. The advantage of the TAC foil could be further enhanced with shape memory alloy (SMA) actuators to control the rear portion of the control surface to form a flexible tab (or FlexTAC) surface. Hybrid unstructured Reynolds averaged Navier–Stokes (RANS) based computational fluid dynamics (CFD) calculations were used to understand the flow physics associated with the multi-element FlexTAC foil with a stabilizer, a flap, and a flexible tab. The prediction results were also compared with the measured data obtained from both the TAC and the FlexTAC experiments. The simulations help explain subtle differences in performance of the multi-element airfoil concepts. The RANS solutions also predict the forces and moments on the surface of the hydrofoil with reasonable accuracy and the RANS procedure is found to be critical for use in a design optimization framework because of the importance of flow separation/turbulent effects in the gap region between the stabilizer and the flap. A systematic optimization study was also carried out with a genetic algorithm (GA) based design optimization procedure. This procedure searches the complex design landscape in an efficient and parallel manner. The fitness evaluations in the optimization procedure were performed with the RANS based CFD simulations. The mesh regeneration was carried out in an automated manner through a scripting process within the grid generator. The optimization calculation is performed simultaneously on both the stabilizer and the nonflexible portion of the flap. Shape changes to the trailing edge of the stabilizer strongly influence the secondary flow patterns that set up in the gap region between the stabilizer and the flap. They were found to have a profound influence on force and moment characteristics of the multi-element airfoil. A new control surface (OptimTAC) was constructed as a result of the design optimization calculation and was shown to have improved lift, drag, and torque characteristics over the original FlexTAC airfoil at high flap angles.
LES of the Slipstream of a Rotating Train
Authors: Hemida Hassan , Gil Nahia , Baker Chris
Published: May 2010

The slipstream of a high-speed train was investigated using large-eddy simulation (LES). The subgrid stresses were modeled using the standard Smagorinsky model. The train model consisted of a four-coach of a 1/25 scale of the ICE2 train. The model was attached to a 3.61 m diameter rotating rig. The LES was made at two Reynolds numbers of 77,000 and 94,000 based on the height of the train and its speed. Three different computational meshes were used in the simulations: course, medium and fine. The coarse, medium, and fine meshes consisted of 6×106, 10×106, and 15×106 nodes, respectively. The results of the fine mesh are in fairly agreement with the experimental data. Different flow regions were obtained using the LES: upstream region, nose region, boundary layer region, intercarriage gap region, tail region, and wake region. Localized velocity peak was obtained near the nose of the train. The maximum and minimum pressure values are also noticed near to the nose tip. Coherent structures were born at the nose and roof of the train. These structures were swept by the radial component of the velocity toward the outer side of the train. These structures extended for a long distance behind the train in the far wake flow. The intercarriage gaps and the underbody complexities, in the form of supporting cylinders, were shown to have large influences on the slipstream velocity. The results showed that the slipstream velocity is linearly proportional to the speed of the train in the range of our moderate Reynolds numbers.
A Method for Three-Dimensional Navier–Stokes Simulations of Large-Scale Regions of the Human Lung Airway
Authors: Walters D. Keith , Luke William H.
Published: May 2010

A new methodology for CFD simulation of airflow in the human bronchopulmonary tree is presented. The new approach provides a means for detailed resolution of the flow features via three-dimensional Navier–Stokes CFD simulation without the need for full resolution of the entire flow geometry, which is well beyond the reach of available computing power now and in the foreseeable future. The method is based on a finite number of flow paths, each of which is fully resolved, to provide a detailed description of the entire complex small-scale flowfield. A stochastic coupling approach is used for the unresolved flow path boundary conditions, yielding a virtual flow geometry that allows accurate statistical resolution of the flow at all scales for any set of flow conditions. Results are presented for multigenerational lung models based on the Weibel morphology and the anatomical data of Hammersley and Olson (1992, “Physical Models of the Smaller Pulmonary Airways,” J. Appl. Physiol., 72(6), pp. 2402–2414). Validation simulations are performed for a portion of the bronchiole region (generations 4–12) using the flow path ensemble method, and compared with simulations that are geometrically fully resolved. Results are obtained for three inspiratory flowrates and compared in terms of pressure drop, flow distribution characteristics, and flow structure. Results show excellent agreement with the fully resolved geometry, while reducing the mesh size and computational cost by up to an order of magnitude.
Analysis and Prevention of Vortex Breakdown in the Simplified Discharge Cone of a Francis Turbine
Authors: Susan-Resiga Romeo , Muntean Sebastian , Hasmatuchi Vlad , Anton Ioan , Avellan François
Published: May 2010

We perform a numerical analysis of the decelerated swirling flow into the discharge cone of a model Francis turbine operated at variable discharge and constant head, using an axisymmetric turbulent swirling flow model and a corresponding simplified computational domain. Inlet boundary conditions correspond to velocity and turbulent kinetic energy profiles measured downstream the Francis runner. Our numerical results are validated against experimental data on a survey section further downstream in the cone, showing that the Reynolds stress turbulence model with a quadratic pressure-strain term correctly captures the flow field. It is shown that the diffuser performance quickly deteriorates as the turbine discharge decreases, due to the occurrence and development of vortex breakdown, with a central quasistagnant region. We investigate a novel flow control technique, which uses a water jet injected from the runner crown tip along the axis. It is shown that the jet discharge can be optimized for minimum overall losses, while the vortex breakdown is eliminated. This flow control method is useful for mitigating the Francis turbine flow instabilities when operating at partial discharge.
Separation of a Two-Phase Slug Flow in Branched 90 deg Elbows
Authors: Sanchez-Silva F. , Hernandez-Perez V. , Carvajal-Mariscal I. , Barbosa-Saldaña J. G. , Cruz-Maya J. A.
Published: May 2010

Novel experimental data for phase separation of air-water mixtures in horizontal 90 deg branched elbows are presented in this work. The branched elbows were formed by attaching a pipe to a 90 deg elbow on the side of maximum radius of curvature, and halfway between the inlet and outlet sections of the elbow. All three arms coming from the junction were in the horizontal plane. Both the branch orientation and branch diameter were varied. Three different branch/elbow diameter ratios were tested, as well as three different branch inclination angles. In addition, the static pressure was monitored at different points along the ramified elbow using a set of pressure transducers in order to analyze and associate the pressure drop with the phase separation. At the inlet section of the elbow, the two-phase flow pattern was mainly slug flow. Based on the experimental data, a correlation for the liquid phase separation is proposed. Finally, the volume-weighted phase separation in the branched elbow was compared with the phase separations on the T-junction, and it was found that in some cases the branched elbows have a similar performance to that of the T-junctions.
Microbubble Drag Reduction Downstream of Ventilated Partial Cavity
Authors: Amromin Eduard
Published: May 2010

The effect of air flux from ventilated partial cavities on drag of bodies was studied. An integral equation method for estimation of air bubble effects on drag was employed and validated with earlier known experimental data for flat plates and bodies. The qualitative difference in the effects of flow speed and air supply rate on drag of flat plates and bodies was numerically confirmed and explained as a combined effect of the boundary layer density decrease and the increase in its displacement thickness. The numerical analysis shows reduction in the total drag of ventilated bodies with increasing air flux rate up to an optimum, but the drag rise for greater rates. A synergy of friction reduction under attached ventilated cavity and microbubble drag reduction downstream of it was shown.
Spectral Linear Stochastic Estimation of the Turbulent Velocity in a Square Three-Dimensional Wall Jet
Authors: Hall Joseph W. , Ewing Daniel
Published: May 2010

The instantaneous turbulent velocity field in a three-dimensional wall jet was estimated from the fluctuating wall pressure using a spectral linear stochastic estimation technique. The wall jet investigated issued from a long square channel with Reynolds number of 90,000. Two downstream positions in the intermediate field were examined, x/h=10 and x/h=20, owing to the rapid changes in wall jet development over this region. The results indicate that the passage of the large-scale structures cause large, coherent lateral sweeps of fluid across the entire span of the wall jet. These sweeps are caused by the passage of half horseshoe-like structures and appear to be responsible for the larger lateral development of this flow.
Flow Characteristics of Microglass Fiber Suspension in Polymeric Fluids in Spherical Gaps
Authors: Yamaguchi Hiroshi , Zhang Xin-Rong , Niu Xiao-Dong , Ito Yuta
Published: May 2010

An experimental study is carried out to investigate the effects of microglass fiber suspensions in the non-Newtonian fluids in a gap between an inner rotating sphere and an outer whole stationary sphere. In the experiments, the microglass fibers with different aspect ratios are mixed with a macromolecule polymeric fluid to obtain different suspension fluids. For comparison, a Newtonian fluid and the non-Newtonian polymeric fluid are also studied. The stationary torques of the inner sphere that the test fluids acted on are measured under conditions of various concentric spherical gaps and rotational Reynolds numbers. It is found that the polymeric fluid could be governed by the Couette flow at a gap ratio of less than 0.42 and the Reynolds number of less than 100, while the fiber-suspended polymeric fluids could expand the Couette flow region more than the Reynolds number of 100 at the same gap ratios.
Shape Optimization of Symmetric Cylinder Shape on Buoyancy Using Fourier Series Approximation
Authors: Kim Hyeongkeun , Choi Dongmin , Kim Youngjin , Baik Seunghyun , Moon Hyungpil
Published: May 2010

The hydrophobicity of water striders and fisher spiders shows the geometrical property of microsetae with elaborate nanogrooves. Studying such geometrical morphology naturally leads to the question: what is an optimal shape for buoyancy? In this paper, we present a methodology to find suboptimal shapes for star-shaped cross-sectional rods, which maximizes the buoyant force by modeling the cross-sectional shapes with Fourier series representation in the polar coordinate. We provide four suboptimal cross-sectional shapes and their experimental results. Our results support the importance of the geometrical shape for buoyant force and might be helpful in designing water repelling devices.
Axial Flow Fan Tip Leakage Flow Control Using Tip Platform Extensions
Authors: Aktürk Ali , Camci Cengiz
Published: May 2010

Performance of an axial flow fan unit is closely related to its tip leakage mass flow rate and level of tip/casing interactions. The present experimental study uses a stereoscopic particle image velocimeter to quantify the three dimensional mean flow observed near the blade tip, just downstream of a ducted fan unit. After a comprehensive description of the exit flow from the baseline fan, a number of novel tip treatments based on custom designed pressure side extensions are introduced. Various tip leakage mitigation schemes are introduced by varying the chordwise location and the width of the extension in the circumferential direction. The current study shows a proper selection of the pressure side bump location and width are the two critical parameters influencing the success of each tip leakage mitigation approach. Significant gains in the axial mean velocity component are observed when a proper pressure side tip extension is used. It is also observed that a proper tip leakage mitigation scheme significantly reduces the tangential velocity component near the tip of the axial fan blade. Reduced tip clearance related flow interactions are essential in improving the energy efficiency of ducted fan systems. A reduction or elimination of the momentum deficit in tip vortices is also essential to reduce the adverse performance effects originating from the unsteady and highly turbulent tip leakage flows rotating against a stationary casing.
Flows and Their Stability in Rotating Cylinders With a Porous Lining
Authors: Subotic M. , Lai F. C.
Published: May 2010

Flow fields in an annulus between two rotating cylinders with a porous lining have been numerically examined in this study. While the outer cylinder is stationary, the inner cylinder is rotating with a constant angular speed. A homogeneous and isotropic porous layer is press-fit to the inner surface of the outer cylinder. The porous sleeve is saturated with the fluid that fills the annulus. The effects of porous sleeve thickness and its properties on the flows and their stability in the annulus are numerically investigated. Three-dimensional momentum equations for the porous and fluid layers are formulated separately and solved simultaneously in terms of velocity and vorticity. The solutions have covered a wide range of the governing parameters (10−5≤Da≤10−2,  2000≤Ta≤5000,  0.8≤b¯≤0.95). The results obtained show that the presence of a porous sleeve generally has a stabilizing effect on the flows in the annulus.
Prediction of the Nonuniform Tip Clearance Effect on the Axial Compressor Flow Field
Authors: Kang Young-Seok , Kang Shin-Hyoung
Published: May 2010

It is well-known that nonuniform tip clearance in an axial compressor induces pressure and velocity perturbations along the circumferential direction. This study develops a numerical modeling to predict perturbed flows in an axial compressor with a nonuniform tip clearance and presents a mechanism of the flow redistribution in the axial compressor at design and off-design conditions. The modeling results are compared with CFD results (2006, “Prediction of the Fluid Induced Instability Force of an Axial Compressor,” ASME FEDSM 2006, Miami, FL) not only to validate the present modeling, but also to investigate more detailed flow fields. In an axial compressor, nonuniform tip clearance varies local flow passage area and resultant axial velocity along the circumferential direction. There are small axial velocity differences between maximum and minimum clearances near the design condition, while large pressure differences are investigated according to local locations. However, contribution of the main flow region overrides the tip clearance effect as the flow coefficient deviates from the design condition. Moreover, the flow field redistribution becomes noticeably strong when the off-design effects are incorporated. In case of high flow coefficients, the low relative flow angle near the minimum clearance regions results in a large negative incidence angle and forms a large flow recirculation region and a corresponding large amount of loss occurs near the blade pressure surface. It further promotes strong flow field perturbations at the off-design conditions. The integration of these pressure and blade loading perturbations with a control volume analysis leads to the well-known Alford’s force. Alford’s force is always negative near the design condition; however, it reverses its sign to positive at the high flow coefficients. At the high flow coefficients, tip leakage flow effects lessen, while increased off-design effects amplify blade loading perturbations and a steep increase in Alford’s force. This study enables that nonuniform flow field, and the resultant Alford’s force, which may result in an unstable rotor-dynamic behavior, can be easily evaluated and assessed during the compressor, fan, or blower design process.
A Study of Cycle-to-Cycle Variations and the Influence of Charge Motion Control on In-Cylinder Flow in an IC Engine
Authors: Mittal Mayank , Schock Harold J.
Published: May 2010

An experimental study is performed to investigate the cycle-to-cycle variations and the influence of charge motion control on in-cylinder flow measurement inside an internal combustion engine assembly. Molecular tagging velocimetry (MTV) is used to obtain the multiple point measurement of the instantaneous velocity field. MTV is a molecular counterpart of particle-based techniques, and it eliminates the use of seed particles. A two-component velocity field is obtained at various crank angle degrees for tumble and swirl measurement planes inside an optical engine assembly (1500 rpm and 2500 rpm engine speeds). Effects of charge motion control are studied considering different cases of: (i) charge motion control valve (CMCV) deactivated and (ii) CMCV activated. Both the measurement planes are used in each case to study the cycle-to-cycle variability inside an engine cylinder. Probability density functions of the normalized circulation are calculated from the instantaneous planar velocity to quantify the cycle-to-cycle variations of in-cylinder flows. In addition, the turbulent kinetic energy of flow is calculated and compared with the results of the probability density function. Different geometries of CMCV produce different effects on the in-cylinder flow field. It is found that the charge motion control used in this study has a profound effect on cycle-to-cycle variations during the intake and early compression; however, its influence reduces during the late compression. Therefore, it can be assumed that CMCV enhances the fuel-air mixing more than the flame speed.
Experimental Study of Turbulence Transport in a Dilute Surfactant Solution Flow Investigated by PIV
Authors: Gu Weiguo , Kawaguchi Yasuo , Wang Dezhong , Akihiro Saito
Published: May 2010

Drag-reducing flow of dilute surfactant solution in the two-dimensional channel is investigated experimentally by using particle image velocimetry (PIV) system. Five hundred instantaneous velocity frames of u-v in the x-y plane are taken by PIV for every condition. Fluctuation intensity and instantaneous velocity distributions are discussed in order to study the turbulence transport in the drag-reducing flow. As compared with water, the results show that wall-normal velocity fluctuations in the drag-reducing flow are suppressed significantly, and instantaneous velocity distributions display different features. Moreover, the drag-reducing flow exhibits the reduced inclination angle of turbulence transport and appearance of “zero Reynolds shear stress.” High shear dissipation also appears in some solutions. Based on the analysis of the balance of mean and mean turbulent kinetic energies, it is found that the complex rheology, i.e., the elasticity and viscosity of the solution, is considered as the main factor that change the characteristics of turbulence transport.
Prion Strain Mutation Determined by Prion Protein Conformational Compatibility and Primary Structure
Authors: Angers Rachel C. , Kang Hae-Eun , Napier Dana , Browning Shawn , Seward Tanya , Mathiason Candace , Balachandran Aru , McKenzie Debbie , Castilla Joaquín , Soto Claudio , Jewell Jean , Graham Catherine , Hoover Edward A. , Telling Glenn C.
Published: May 2010

CWD Strain Variation

So-called prion diseases are fatal neurogenerative disorders that include chronic wasting disease (CWD) found in deer and other cervids. Prion diseases are thought to be caused by infectious proteins (prions) in the absence of associated infectious DNA. Nevertheless, prion strains have been isolated that can mutate in the absence of nucleic acids, and these strain properties control the ability of prions to cross species barriers.

Angers
et al.

(p.
1154
, published online 13 May; see the Perspective by

Collinge

) address the issue of strain variation in the context of CWD. Whereas the host range of this contagious disease continues to expand, the prevalence of CWD strains has not been determined. Understanding CWD strain variation may be important in predicting and preventing any future risks to human health.
Collective Lamb Shift in Single-Photon Superradiance
Authors: Röhlsberger Ralf , Schlage Kai , Sahoo Balaram , Couet Sebastien , Rüffer Rudolf
Published: May 2010

All Together Now

An atom, when excited, will typically decay with a characteristic decay time. An ensemble of atoms, collectively coupled together with just one of the atoms excited will conspire to decay much faster than the single atom case. This enhancement of light-matter interaction is known as superradiance.

Röhlsberger
et al.

(p.
1248
, published online 13 May; see the cover; see the Perspective by

Scully and Svidzinsky

) present the realization of an artificial superradiant system comprising resonant iron atoms embedded in a semiconductor cavity and excited by synchrotron radiation and report the signature collective Lamb shift expected from the cooperative interaction and enhanced decay rate. The availability of such a controlled system to look closer at this effect should shed light on its role in natural and complex light-harvesting systems, and possibly allow the production of more efficient solar cells.
Mirid Bug Outbreaks in Multiple Crops Correlated with Wide-Scale Adoption of Bt Cotton in China
Authors: Lu Yanhui , Wu Kongming , Jiang Yuying , Xia Bing , Li Ping , Feng Hongqiang , Wyckhuys Kris A. G. , Guo Yuyuan
Published: May 2010

Collateral Damage

Cotton crops that have been bioengineered to express the insecticidal toxin derived from
Bacillus thuringiensis
(Bt) carry their own insect control, particularly against the cotton bollworm, and are less dependent on externally applied pesticides.

Lu
et al.

(p.
1151
, published online 13 April) now show that reduction in general pesticide use in cotton-growing regions of northern China has shifted the balance of regional pest populations. Bt-expressing cotton now serves as a source of herbivorous insects of the Miridae family, rather than the sink that nonengineered cotton was when less specific pesticides were used. Because these insects will eat a variety of plants, they are emerging as a threat to other crops, including grape, apple, peach, and pear.
MicroRNA-33 and the SREBP Host Genes Cooperate to Control Cholesterol Homeostasis
Authors: Najafi-Shoushtari S. Hani , Kristo Fjoralba , Li Yingxia , Shioda Toshi , Cohen David E. , Gerszten Robert E. , Näär Anders M.
Published: May 2010

miR-33 in Cholesterol Control

With the well-established link between serum cholesterol levels and cardiovascular disease and the availability of effective cholesterol-lowering drugs, cholesterol screening has rapidly become a routine part of health care. Yet, much remains to be learned about how cholesterol levels are regulated at the cellular level (see the Perspective by

Brown
et al.

). Now,

Najafi-Shoushtari
et al.

(p.
1566
, published online 13 May) and

Rayner
et al.

(p.
1570
, published online 13 May) have discovered a new molecular player in cholesterol control—a small noncoding RNA that, intriguingly, is embedded within the genes coding for sterol regulatory element-binding proteins (SREBPs), transcription factors already known to regulate cholesterol levels. This microRNA, called miR-33, represses expression of the adenosine triphosphate–binding cassette transporter A1, a protein that regulates synthesis of high-density lipoprotein (HDL, or “good” cholesterol) and that helps to remove “bad” cholesterol from the blood. Reducing the levels of miR-33 in mice boosted serum HDL levels, suggesting that manipulation of this regulatory circuit might be therapeutically useful.
Genetic Evidence for High-Altitude Adaptation in Tibet
Authors: Simonson Tatum S. , Yang Yingzhong , Huff Chad D. , Yun Haixia , Qin Ga , Witherspoon David J. , Bai Zhenzhong , Lorenzo Felipe R. , Xing Jinchuan , Jorde Lynn B. , Prchal Josef T. , Ge RiLi
Published: May 2010

No Genetic Vertigo

Peoples living in high altitudes have adapted to their situation (see the Perspective by

Storz

). To identify gene regions that might have contributed to high-altitude adaptation in Tibetans,

Simonson
et al.

(p.
72
, published online 13 May) conducted a genome scan of nucleotide polymorphism comparing Tibetans, Han Chinese, and Japanese, while

Yi
et al.

(p.
75
) performed comparable analyses on the coding regions of all genes—their exomes. Both studies converged on a gene,
endothelial Per-Arnt-Sim domain protein 1
(also known as
hypoxia-inducible factor 2
α), which has been linked to the regulation of red blood cell production. Other genes identified that were potentially under selection included adult and fetal hemoglobin and two functional candidate loci that were correlated with low hemoglobin concentration in Tibetans. Future detailed functional studies will now be required to examine the mechanistic underpinnings of physiological adaptation to high altitudes.
SPECTRAL SHIFT FUNCTION FOR OPERATORS WITH CROSSED MAGNETIC AND ELECTRIC FIELDS
Authors: DIMASSI MOUEZ , PETKOV VESSELIN
Published: May 2010

We obtain a representation formula for the derivative of the spectral shift function ξ(λ; B, ∊) related to the operators [Formula: see text] and H(B, ∊) = H0(B, ∊) + V(x, y), B > 0, ∊ > 0. We establish a limiting absorption principle for H(B, ∊) and an estimate [Formula: see text] for ξ′(λ; B, ∊), provided λ ∉ σ(Q), where [Formula: see text].
EXCITON STATES AND INTERBAND TRANSITIONS IN THE DIRECT-GAP Ge/SiGe QUANTUM DOT
Authors: XIA CONGXIN , LIU YAMING , WEI SHUYI
Published: May 2010

The ground-state exciton binding energy and interband emission wavelength in the direct-gap Ge / SiGe quantum dot (QD) are investigated by means of a variational approach, within the framework of effective-mass approximation. Numerical results show that the ground-state exciton binding energy has a maximum value with increasing quantum size of the direct-gap Ge / SiGe QD. The interband emission wavelength is increased when the QD size is increased. Our results indicate the direct-gap Ge / SiGe QD can be applied for long wavelength optoelectronic devices.
SIMULATION AND ANALYSIS OF ASYMMETRIC METAMATERIAL RESONATOR-ASSISTED MICROWAVE SENSOR
Authors: YANG JINGJING , HUANG MING , XIAO ZHE , PENG JINHUI
Published: May 2010

Based on the field enhancement principle of trapped modes, two new asymmetric metamaterial resonators are presented. Transmission response (S21) of the rectangular wave-guide filled with an asymmetric metamaterial resonator is simulated. Results show that the asymmetric resonator possesses high Q-factor and improved sensitivity. The microwave sensor based on the asymmetric resonator can be flexibly tailored to design requirement by varying the asymmetry parameter or the topological structure of the resonator. The asymmetric metamaterial resonator-assisted microwave sensor will have potential applications in biosensor and chemosensor fields for sensing minute amounts of dielectric sample substance.
A NEW ANALYTICAL MODEL FOR HEAT TRANSFER IN POOL BOILING
Authors: XIAO BOQI
Published: May 2010

In this paper, dependence of active nucleation site density on boiling surfaces are developed. For pool boiling heat transfer, a mathematical model is derived based on statistical treatment using the probability density function of the cavity mouth radius and existing correlation for active nucleation site density, the volume of single bubble at departure, the bubble departure diameter and the bubble departure frequency. The proposed model is expressed as a function of wall superheat, the contact angle, maximum and minimum active cavities, and physical properties of fluid. It is shown that the wall heat flux can be determined by the consideration of the variation of the cavity mouth radius. A good agreement between the proposed model predictions and experimental data is found for different contact angles. It also turns out that the present model explains well the mechanism on how wettability affects the pool boiling.
THE TRANSPORT PROPERTIES OF GRAPHENE T-TYPE STRUCTURE
Authors: YIN HUIQIONG
Published: May 2010

The transport properties of graphene T-type structure (GTS), both armchair-edged and zigzag-edged, are studied systematically within Landauer formalism in terms of tight binding Green's function method. For armchair-edged GTS (AGTS), a phase diagram of conductance in parameter space of Fermi energy and the stub width is presented. When a gate voltage is applied in the stub, a perfect linear dependence of the gap position shift of conductance on the gate voltage is found. The origin of the conductance gap as well as such linear behavior is explained. For the zigzag-edged GTS (ZGTS), it is found that the dependence of the transport properties on the stub height can be classified into two groups that tightly depend on whether the stub width equals 3n-1 or not.
FROM BECQUEREL TO NANOTECHNOLOGY: ONE CENTURY OF DECLINE OF SCIENTIFIC DISSEMINATION, PUBLISHING AND TECHNOLOGY TRANSFER
Authors: MARGARITONDO G.
Published: May 2010

2008 marks the 100th anniversary of Henri Becquerel's death, the discoverer of radioactivity and a leading contributor to the birth of modern physics. In addition to well-deserved celebrations, this offers a chance for a sobering look at scientific dissemination then and now and at the evolution of technology transfer. The facts are shocking: both dissemination and technology transfer were much faster and effective at the time of Becquerel, in spite of all the new communication techniques. I briefly speculate on the causes of these dismal failures, arguing that they are primarily rooted in society, academic management and industrial management — and therefore very difficult to reverse.
Segregation of Na/H exchanger-3 and Cl/HCO3exchanger SLC26A3 (DRA) in rodent cecum and colon
Authors: Talbot Colleen , Lytle Christian
Published: May 2010

The colon is believed to absorb NaCl via the coupled operation of apical Na/H exchanger-3 (NHE3) and Cl/HCO3exchanger SLC26A3 (DRA). Efficient coupling requires that NHE3 and DRA operate in close proximity within common luminal and cytosolic microenvironments. Thus we examined whether these proteins coexist along the apical margin of surface enterocytes by quantitative immunofluorescence microscopy in consecutive colon segments from nonfasted mice and rats. The cecocolonic profiles of NHE3 and DRA expression were roughly inverse; NHE3 was highest in proximal colon (PC) and negligible in distal colon, whereas DRA was absent in early PC and highest in the late midcolon, and DRA was prominent in the cecum whereas NHE3 was not. NHE3 and DRA coexisted only in the middle third of the colon. The consequences of unpaired NHE3/DRA expression on mucosal surface (subscript MS) pH and Na+concentration ([Na+]) were assessed in nonfasted rats in situ using miniature electrodes. In the cecum, where only DRA is expressed, pHMSwas ∼7.5, markedly higher than underlaying stool (6.3), consistent with net HCO3−secretion. In the early PC, where NHE3 is not expressed with DRA, pHMSwas acidic (6.2), consistent with unopposed H+secretion. [Na+]MSwas ∼60 mM in the cecum, decreased along the PC to ∼20 mM, and declined further to ∼10 mM distally. Cl−was secreted into the PC, then reabsorbed distally. Our results suggest a model in which 1) unpaired DRA activity in the cecum maintains an alkaline mucosal surface that could neutralize fermentative H+; 2) unpaired NHE3 activity in the early PC preserves an acidic mucosal surface that could energize short-chain fatty acid absorption; and 3) coupled NHE3/DRA activities in the midcolon allow for vigorous NaCl absorption at a neutral pHMS.
Characterization of apical and basal thiol-disulfide redox regulation in human colonic epithelial cells
Authors: Mannery Yanci O. , Ziegler Thomas R. , Hao Li , Shyntum Yvonne , Jones Dean P.
Published: May 2010

Control of extracellular thiol-disulfide redox potential (Eh) is necessary to protect cell surface proteins from external oxidative and reductive stresses. Previous studies show that human colonic epithelial Caco-2 cells, which grow in cell culture with the apical surface exposed to the medium, regulate extracellular cysteine/cystine Ehto physiological values (approximately −80 mV) observed in vivo. The present study tested whether extracellular Ehregulation occurs on the basal surface of Caco-2 cells and investigated relevant mechanisms. Experiments were performed with confluent, differentiated cells grown on a permeable membrane surface. Cells were exposed to an oxidizing potential (0 mV) using a fixed cysteine-to-cystine ratio, and culture medium was sampled over time for change in Eh. Regulation of extracellular thiol-disulfide Ehon the basal domain was faster, and the extent of change at 24 h was greater than on the apical surface. Mechanistic studies showed that redox regulation on the basal surface was partially sodium dependent and inhibited by extracellular lysine, a competitive inhibitor of cystine transport by the y+L system and by quisqualic acid, an inhibitor of the xc−system. Studies using the thiol-reactive alkylating agent 4-acetamido-4′-maleimidylstilbene-2,2′-disulfonic acid and the glutathione synthesis inhibitor buthionine sulfoximine showed that extracellular redox regulation was not attributable to plasma membrane cysteine/cystine interconversion or intracellular glutathione, respectively. Thus the data show that redox regulation occurs at different rates on the apical and basal surfaces of the polarized Caco-2 epithelial cell line and that the y+L and xc−systems function in extracellular cysteine/cystine redox regulation on the basal surface.
Microbiota matures colonic epithelium through a coordinated induction of cell cycle-related proteins in gnotobiotic rat
Authors: Cherbuy Claire , Honvo-Houeto Edith , Bruneau Aurélia , Bridonneau Chantal , Mayeur Camille , Duée Pierre-Henri , Langella Philippe , Thomas Muriel
Published: May 2010

Previous studies have suggested that intestinal microbiota modulates colonic epithelium renewal. The objective of our work was to study the effects of microbiota on colonic epithelium structure and cell cycle-related proteins by using gnotobiotic rats. Colonic crypts and amount of cell cycle-related proteins were compared between germ-free (GF), conventional (CV), and conventionalized rats by histochemistry and Western blot. Ki67 and proliferating cell nuclear antigen (PCNA) were used as surrogates for proliferative cells; p21cip1and p27kip1were markers of cell cycle arrest; anti- and proapoptotic proteins, Bcl2 and Bax, respectively, were also studied. We observed 40% increase of the crypt proliferative area 2 days after inoculation of GF rats with a complex microbiota. This recruitment of proliferative cells may account for the 30% increase of crypt depth observed between CV and GF rats. The hyperproliferative boost induced by microbiota was compensated by a fourfold increase of p21cip1and p27kip1involved in cell cycle arrest and a 30% drop of antiapoptotic Bcl2 protein while Bax was unchanged. Inductions of p21cip1, p27kip1, and PCNA protein were not paralleled by an increase of the corresponding mRNA. We also showed that p21cip1induction by microbiota was partially restored by Bacteroides thetaiotaomicron , Ruminococcus gnavus , and Clostridium paraputrificum . Colonization of the colon by a complex microbiota increases the crypt depth of colon epithelium. This event takes place in conjunction with a multistep process: a hyperproliferative boost accompanied by compensatory events as induction of p21cip1and p27kip1and decrease of Bcl2.
Transgenic overexpression of pregnancy-associated plasma protein-A in murine arterial smooth muscle accelerates atherosclerotic lesion development
Authors: Conover Cheryl A. , Mason Megan A. , Bale Laurie K. , Harrington Sean C. , Nyegaard Mette , Oxvig Claus , Overgaard Michael T.
Published: May 2010

Pregnancy-associated plasma protein-A (PAPP-A) increases local IGF-I bioavailability through cleavage of inhibitory IGF binding protein (IGFBP)-4 in a variety of systems, including the cardiovascular system. To test the hypothesis that expression of PAPP-A promotes the development of atherosclerotic lesions, we generated transgenic mice that express human PAPP-A in arterial smooth muscle. Four founder lines were characterized for transgenic human PAPP-A mRNA and protein expression, IGFBP-4 protease activity, and tissue specificity. In study I, apolipoprotein E knockout (ApoE KO) mice, a well-characterized mouse model of atherosclerosis, and ApoE KO mice expressing the human PAPP-A transgene at relatively high levels (ApoE KO/Tg) were fed a high-fat diet. At harvest, aortas were dissected and opened longitudinally for en face staining of lipid-rich lesions. Lesion area was increased 3.5-fold in aortas from ApoE KO/Tg compared with ApoE KO mice ( P < 0.001), but no significant difference was seen in lesion number. In study II, replacement of PAPP-A expression in arterial smooth muscle of double ApoE KO/PAPP-A KO mice resulted in a 2.5-fold increase in lesion area ( P = 0.002), without an effect on lesion number. PAPP-A transgene expression was associated with a significant increase in an IGF-responsive gene ( P < 0.001), suggesting increased local IGF-I action. We therefore conclude that expression of human PAPP-A localized to arterial smooth muscle accelerates lesion progression in a mouse model of atherosclerosis. These data provide further evidence for the importance of PAPP-A in the cardiovascular system and suggest PAPP-A as a potential therapeutic target in the control of atherosclerosis.
β-Catenin regulates airway smooth muscle contraction
Authors: Jansen Sepp R. , Van Ziel Anna M. , Baarsma Hoeke A. , Gosens Reinoud
Published: May 2010

β-Catenin is an 88-kDa member of the armadillo family of proteins that is associated with the cadherin-catenin complex in the plasma membrane. This complex interacts dynamically with the actin cytoskeleton to stabilize adherens junctions, which play a central role in force transmission by smooth muscle cells. Therefore, in the present study, we hypothesized a role for β-catenin in the regulation of smooth muscle force production. β-Catenin colocalized with smooth muscle α-actin (sm-α-actin) and N-cadherin in plasma membrane fractions and coimmunoprecipitated with sm-α-actin and N-cadherin in lysates of bovine tracheal smooth muscle (BTSM) strips. Moreover, immunocytochemistry of cultured BTSM cells revealed clear and specific colocalization of sm-α-actin and β-catenin at the sites of cell-cell contact. Treatment of BTSM strips with the pharmacological β-catenin/T cell factor-4 (TCF4) inhibitor PKF115-584 (100 nM) reduced β-catenin expression in BTSM whole tissue lysates and in plasma membrane fractions and reduced maximal KCl- and methacholine-induced force production. These changes in force production were not accompanied by changes in the expression of sm-α-actin or sm-myosin heavy chain (MHC). Likewise, small interfering RNA (siRNA) knockdown of β-catenin in BTSM strips reduced β-catenin expression and attenuated maximal KCl- and methacholine-induced contractions without affecting sm-α-actin or sm-MHC expression. Conversely, pharmacological (SB-216763, LiCl) or insulin-induced inhibition of glycogen synthase kinase-3 (GSK-3) enhanced the expression of β-catenin and augmented maximal KCl- and methacholine-induced contractions. We conclude that β-catenin is a plasma membrane-associated protein in airway smooth muscle that regulates active tension development, presumably by stabilizing cell-cell contacts and thereby supporting force transmission between neighboring cells.