bluuebunny/crossref_metadata_2025 huggingface dataset:
What Do People Infer from Social Comparisons? Bridges between Social Comparison and Person Perception
Authors: Hoorens Vera , Damme Carolien Van
Published: August 2012

Human judgment is basically comparative, with self‐judgments in particular being based on social comparison. Not surprisingly, much research has focused on how self‐comparisons shape comparers’ self‐views on the specific comparison dimension. We argue that both comparers and observers may, and do, draw various other inferences and that they do so from both self‐comparisons and other‐comparisons. In both cases they may draw inferences from (a) the fact that social comparison has taken place, (b) the allocation of the target and referent roles, and (c) the stated relationship between the target and the referent. In order to show how exploring these inferences may lead social comparison research into new and exciting directions, we point out some unanswered questions about them.
Provincialising Lakatoro: Orienting sociality through a state institution in Vanuatu
Authors: Rousseau Benedicta
Published: August 2012

Focusing on Lakatoro, a provincial centre in Vanuatu, this article explores the ways in which a state institution may allow kastom‐based sociality to proceed for the local population. Rather than considering kastom and the state as necessarily separate, it is demonstrated that the institutions of the state can provide the objective forms needed for kastom to exist in urban space. The article discusses three ways in which this happened—through a staff handbook, daily prayer meetings, and a court case—arguing that ‘the province’s’ polyvalence provided a means by which Lakatoro could be experienced as a place. And that this, in turn, provided a way in which the local population could understand the town to be imbued with appropriate sociality, as measured by kastom.
Assessing the Existing Information on the Efficacy of Bovine Vaccination against Escherichia coli O157:H7 – A Systematic Review and Meta‐analysis
Authors: Varela N. P. , Dick P. , Wilson J.
Published: August 2012

The objective of this study was to conduct a systematic review and meta‐analysis to evaluate the existing information on the efficacy of commercial vaccination to reduce the prevalence of Escherichia coli O157:H7 in weaned cattle in beef feedlot finishing systems under commercial conditions. Currently, only two commercial vaccines exist, and thus, only publications reporting the use of vaccines targeting type III secreted proteins and/or siderophore receptor and porin proteins (SRP) were considered relevant. A total of 18 studies reporting 45 comparisons were included in this review. Meta‐analyses were conducted variously on (i) pre‐harvest outcomes, (ii) at‐harvest outcomes and (iii) both pre‐harvest and at‐harvest outcomes combined. Overall, efficacy of vaccination was consistently observed. Efficacy and homogeneity of the results was demonstrated for the two‐dose regimen, allowing us to conclude with confidence that the two‐dose approach is efficacious. For pre‐harvest outcomes and two‐dose regimens, the odds ratios (OR) were 0.53 (95% CI = 0.45–0.62) for the two vaccines combined and 0.49 (95% CI = 0.40–0.60) for vaccine targeting type III secreted proteins. The test for heterogeneity among studies yielded a Q test P = 0.354 for the two vaccines combined and Q test P = 0.269 for the vaccine targeting type III secreted proteins, indicating homogeneity in both cases. For pre‐ and at‐harvest outcomes combined and two‐dose regimens, the odds ratios (OR) were 0.52 (95% CI = 0.44–0.61) for the two vaccines combined and 0.45 (95% CI = 0.34–0.60) for vaccine targeting type III secreted proteins. The test for heterogeneity among studies yielded a Q test P = 0.134 for the two vaccines combined indicating homogeneity and Q test P = 0.089 for the vaccine targeting type III secreted proteins indicating heterogeneity. Based on this meta‐analysis, bovine vaccination appears to be an effective approach to the pre‐harvest control of E. coli O157:H7.
Complementary and alternative medicine for diabetes mellitus: an overview of systematic reviews
Authors: Posadzki Paul , Lee Myeong Soo , Ernst Edzard
Published: August 2012

Background  Many patients with diabetes mellitus report the use of CAM.

Objectives  To summarise and critically evaluate systematic reviews of any type of CAM for the treatment of diabetes.

Methods  Four electronic databases were searched to identify all relevant systematic reviews published between January 2000 and May 2011.

Results  Twelve systematic reviews met the inclusion criteria. These reviews evaluated the effectiveness of any type of CAM, herbal medicine, qi gong, tai chi, massage, moxibustion and yoga for the treatment and/or management of diabetes mellitus. Reviews also assessed the effectiveness of: pharmacological and lifestyle interventions to prevent or delay the onset of the disease; the effectiveness of herbal remedies and dietary supplements for glucose control; and the effectiveness of yoga‐based programmes on physiologic and anthropometrical risk profiles and related clinical outcomes. Six reviews were of high quality and six indicated high risk of bias. Eleven reviews arrived at cautious or negative conclusions. One systematic review of massage reported positive conclusions.

Conclusions  Evidence supporting the effectiveness of CAM as a treatment option for diabetes is scarce.
Ageratina pichinchensis extract for chronic venous leg ulcers
Authors: Chrubasik S
Published: August 2012

Romero‐Cerecero O, Zamilpa‐Álvarez A, Jiménez‐Ferrer E, Tortoriello J.

Exploratory study on the effectiveness of a standardized extract from Ageratina pichinchensis in patients with chronic venous leg ulcers.

Planta Med 2012; 78: 304–10.
Integrative medicine and cancer therapy – another missed opportunity
Authors: Baum M
Published: August 2012

Judson PL, Dickson EL, Argenta PA, Xiong Y, Geller MA, Carson LF, et al.

A prospective, randomised trial of integrative medicine for women with ovarian cancer.

Gynecol Oncol 2011; 123: 346–50
Nonclassical Heat Transfer Models for Laser-Induced Thermal Damage in Biological Tissues
Authors: Zhou Jianhua , Chen J. K. , Zhang Yuwen
Published: August 2012

To ensure personal safety and improve treatment efficiency in laser medical applications, one of the most important issues is to understand and accurately assess laser-induced thermal damage to biological tissues. Biological tissues generally consist of nonhomogeneous inner structures, in which heat flux equilibrates to the imposed temperature gradient via a thermal relaxation mechanism which cannot be explained by the traditional parabolic heat conduction model based on Fourier’s law. In this article, two non-Fourier heat conduction models, hyperbolic thermal wave model and dual-phase-lag (DPL) model, are formulated to describe the heat transfer in living biological tissues with blood perfusion and metabolic heat generation. It is shown that the non-Fourier bioheat conduction models could predict significantly different temperature and thermal damage in tissues from the traditional parabolic model. It is also found that the DPL bioheat conduction equations can be reduced to the Fourier heat conduction equations only if both phase lag times of the temperature gradient (τT) and the heat flux (τq) are zero. Effects of laser parameters and blood perfusion on the thermal damage simulated in tissues are also studied. The result shows that the overall effects of the blood flow on the thermal response and damage are similar to those of the time delay τT. The two-dimensional numerical results indicate that for a local heating with the heated spot being smaller than the tissue bulk, the variations of the non-uniform distributions of temperature suggest that the multi-dimensional effects of thermal wave and diffusion not be negligible.
Understanding Why Codes and Standards Fail
Authors: Batzer Stephen A. , Morse John S. , Lee Dong Y. Don
Published: August 2012

The enduring issues regarding codes and standards for consumer products and corporate behavior are discussed in this paper. It has been frequently asserted that the adherence of a product to a recognized government or private standard ensures that the product has a minimal level of safety, and that said product is therefore presumably non-defective. The agencies which promulgate these codes and standards are ostensibly impartial and informed, and have the public’s best interests in mind. This conviction is undoubtedly true in some instances, but is also unquestionably false in others. The issues regarding codes and standards and their impact upon products and the trusting public include, but are not limited to, asymmetric information, cost concerns, ethics, foreseeable misuses, non-alignment of interests, and technological advancements after the standards were adopted. In short, the adherence to the letter, rather than the spirit, of individual codes and standards is a manifestation of the Principal-Agent conflict, in which the agent, acting on behalf of the principal, has a different set of incentives than does the principal. This conflict and the underlying issues listed above are discussed. Case studies of numerous products with possible, known, and unforeseen adverse impacts upon public health and safety will be used as illustrations of products that were within the letter of the code or standard, but manifestly defective.
Gerotor Fuel Pump Performance and Leakage Study
Authors: Ruvalcaba Mario Alberto , Hu Xiao
Published: August 2012

Gerotor pumps are utilized in a number of automotive applications such as fuel lift. Volumetric efficiency and leakage are causes of concern in gerotor pumps. To optimize pump performance and reduce leakage, it is fundamental to comprehend the fluid dynamics inside the pump passageways. In this paper, a three-dimensional CFD methodology has been developed and applied to predict the pump performance, to understand pump flow dynamics and to investigate pump leakage for gerotor pumps equipped in automotive fuel systems. The methodology is based in the commercial code ANSYS FLUENT and the analytical focal points are the pump performance and leakage over a range of motor speeds and output pressures, 4000 RPM and 5400 RPM, also 450 kPa and 600 kPa. The CFD results are first contrasted with the experimental data and a very good agreement has been achieved. Extensive CFD simulations are then conducted to study the effect of the tip clearance on pump flow performance and leakage.
Thermal Performance Evaluation of Seawater Cooling Towers
Authors: Sharqawy Mostafa H. , Husain Iqbal S. , Zubair Syed M. , Lienhard John H.
Published: August 2012

Seawater has been used for long time as a cooling fluid in heat exchangers to reduce fresh water usage in industry and power plants. The thermophysical properties of seawater are different from those of fresh water due to the salt content or salinity. This difference is sufficient to affect the heat and mass transfer processes which in turn change the thermal performance. Thermal design of fresh water cooling towers is described in detail in many textbooks and handbooks. However, only a rule of thumb is frequently used for designing of seawater cooling towers. This rule recommends degrading the tower performance by approximately 1% for every 10,000 ppm of salts in the feed water. In this paper, the thermal performance of seawater cooling towers is presented using a detailed model of counterflow wet cooling towers which takes into consideration the coupled simultaneous heat and mass transfer processes and uses state-of-the-art seawater properties from the literature. The model governing equations are solved numerically and the validity of this model is checked using new experimental data that has been measured using a bench top counterflow seawater cooling tower. The effect of the variation of seawater salinity as well as other operating conditions on the effectiveness and Merkel number is investigated.
Stack Effect Correlation for Rooftop Solar Chimneys
Authors: Naraghi Mohammad H. , du Sordet Romain Cellard
Published: August 2012

A correlation for calculating flow rate of air in solar chimneys is developed. This correlation is based on the variables that have the most direct influence on the volume flow rate of air through a solar chimney. These variables include: the spacing between the absorbing wall and glass (chimney depth), absorbing wall temperature, inlet air temperature and height of chimney. The slope of the rooftop solar chimney, for the range of typical roofs (30°–60°) has very little influence on the flow rate. The solution of energy balance equations for various components of the solar chimney along with the newly developed correlation shows a significant improvement of the results compared to the existing stack effect correlation.
Numerical Investigation of an Impingement Flow due to a Free Surface Axisymmetric Long Water Jet
Authors: Seraj M. M. , Gadala M. S.
Published: August 2012

The hydrodynamics of impingement flow is a key partner of heat transfer analysis of run-out table (ROT) cooling. The long circular free-surface water jets with industrial parameters (e.g. Re = 16,000–50,000) were numerically simulated by laminar and two variants of turbulent k-ε and k-ω models where the effect of gravity is significant. The development of water impingement film was computed and compared with the experimental data which obtained from the ROT facility. The propagation of water flow over the impingement surface is better simulated by Shear Stress transition k-ω (SST) model. The impingement flow features such as jet deceleration before hitting wall and velocity and pressure profiles were compared with short jet data to explore common flow characteristics between the short and long jets. The effect of target surface on retardation of long turbulent liquid jet before incident is pronouncing as jet Reynolds number increased. However, the velocity reduction is not noticeable until where the speed of short jet starts decreasing. In impingement zone, the flow radial velocity varies linearly similar to short liquid jets which gravity effect is neglected. But, the velocity gradient was found higher which shows enhanced heat transfer for a long turbulent water jet. The dimension of impingement zone as an influential region in boiling heat transfer analysis is found smaller respect to the estimation which used in ROT modeling. The effect of local impingement pressure on saturation temperature is found important in stagnation zone which influences the prediction of heat fluxes by boiling heat transfer correlations up to 9%. This has to be considered in ROT modeling where the heat flux can be as high as 10 Mw/m2.
Experimental Study on Biaxial Ratcheting of SS316LN Steel Pipes Used in Fast Breeder Reactor Structures
Authors: Athmanathan S. , Dandu Bharath Kumar , Lakshmana Rao C. , Krishnan Santhana , Suresh Kumar R. , Pandi Chella
Published: August 2012

SS316LN is the primary material used for critical components in fast breeder reactors. Piping systems play a vital role in the operation of any reactor. Fast breeder reactor piping system carries sodium at high temperatures. These systems are operated for long durations. Under normal operating conditions, these piping systems are under tensile stress due to internal pressure and self weight. In case of any seismic excitations, these piping systems are subjected to cyclic torsion along with the constant tensile stress. The combination of static axial tension and large magnitude of cyclic torsion leads to accumulation of plastic strains in axial direction. This accumulation of plastic strain in the axial direction due to cyclic torsion is called ratcheting. This paper discusses about the experimental investigations carried to simulate ratcheting behavior of the SS316L (N) pipe specimen. Many specimens tested under various loading combinations of constant axial tension and cyclic shear strain. The ratcheting for the material SS316LN has been observed experimentally. Axial strain variation with number of cycles is obtained for various loading cases. All these experiments have been conducted in room temperature.
Impedance Control of Gyroscopic Power Generator
Authors: Takahashi Tomoyuki , Iwasaki Jun , Hosaka Hiroshi
Published: August 2012

The gyroscopic power generator produces a high-speed rotation of magnets from low-frequency vibrations and supplies electric power to information and communication devices that use human vibrations in daily life. In this paper, in order to increase the stability and the output power of the generator, a simple equation that indicates the steady state approximate solution of the phase difference is derived. From the derived solution, a control method for the steady state is verified by the simulations. In order to maintain the stability and high power generation for variable input vibrations, the impedance control method using the phase difference is developed and verified experimentally.
Generation of Nonthermal Atmospheric Pressure Plasma in Microchannel Reactor and Induction of Cell Death by an Electric Field of Plasma
Authors: Park Hyoun-Hyang , Song Young-Hoon , Lee Seung S. , Lee Dae Hoon
Published: August 2012

This paper reports the construction of a microchannel reactor that eliminates arc transitions and streamer generation under atmospheric conditions. The micromachined dielectric barrier discharge reactor suppresses streamer generation resulting in homogeneous discharges even in a high electric field of 170kV/cm. Only electric field without discharge exists in the microchannel reactor when cells suspended in a fluid are passed through the reactor. The electric field of NTAP induces cell death.
Simulations and Measurements of Water Vapor Flow and Ice Dynamics in a Freeze-Dryer Condenser
Authors: Ganguly Arnab , Alexeenko Alina , DeMarco Frank
Published: August 2012

Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of pharmaceuticals for removal of solvents by sublimation. The performance of a freeze-dryer condenser is largely dependent on the vapor and ice dynamics in the low-pressure environment. The main objective of this work is to develop a modeling and computational framework for analysis of vapor flow and ice dynamics in such freeze-dryer condensers. The direct Simulation Monte Carlo (DSMC) technique is applied to model the relevant physical processes that accompany the vapor flow in the condenser chamber. Low-temperature water vapor and nitrogen molecular model is applied in the DSMC solver SMILE to simulate the bulk vapor transport. The developing ice front on the coils of the condenser is tracked based on the steady state mass flux computed at the nodes of the DSMC surface mesh. Verification of ice accretion simulations has been done by comparison with the solution for analytical free-molecular flow over a circular cylinder. The developed model has also been validated with measurements of ice growth in a laboratory and production scale freeze-dryer using time-lapse imaging. To illustrate the application of the ice accretion algorithm in the area of bio-pharmaceutical freeze-drying, the current work discusses the effect of the condenser geometry and non-condensable gas on non-uniformity of mass flux in a laboratory scale and production scale freeze-dryer condenser. In addition, the simulations are used to predict the ice formation on the coils of the condenser. It was found that in the laboratory scale dryer, the presence of a duct connecting the product chamber and condenser increased non-uniformity by 65% at a sublimation rate of 5 g/hr. The measured ice thickness on the coils of the condenser was found to increase non-linearly. This non-linearity was captured within an accuracy of 1% compared to the measurements towards the end of a 24 hour cycle using an unsteady icing model while that using a steady model was within 14%. In the production dryer, while the steady model predicted the iced coil diameter within an accuracy of 2–5% with respect to the measurements, the unsteady model captured this within an accuracy of 1–6%. The DSMC simulations demonstrate that by augmenting its capabilities with the icing model, it is possible to predict the performance of a freeze-dryer condenser with any arbitrary design.
An Experimental Investigation of Steam Ejector Refrigeration Systems
Authors: Dong J. M. , Pounds D. A. , Cheng P. , Ma H. B. , Pan X. X.
Published: August 2012

A steam ejector refrigeration system with a movable primary nozzle was developed in order to determine the nozzle exit position (NXP) effect on the coefficient of performance (COP). Experimental results show that an optimum NXP exists for the ejector system investigated herein. In addition, the effects of the operation temperature, diffuser size, nozzle throat diameter, and structure of mixing chamber on the COP and cooling capacity were conducted experimentally. It was found that the critical condenser pressure and COP can be increased by increasing the low-temperature-evaporator (LTE) temperature and pressure. Although an increase of the high-temperature-evaporator (HTE) can increase the critical condenser pressure, the system COP did not increase as the HTE temperature increased. While the diffuser size significantly affected the critical back pressure, it had almost no effect on the system COP. A finned mixing chamber was tested at NXP = 0mm and NXP = 36mm. Compared with the regular mixing chamber, the finned mixing chamber can increase the critical back pressure. The results provide a better understanding of heat transfer and fluid flow mechanisms occurring in a steam ejector refrigeration system.
Adhesion of Chlorella vulgaris on Hydrophilic and Hydrophobic Surfaces
Authors: Ozkan Altan , Berberoglu Halil
Published: August 2012

This experimental study reports the adhesion rate and adhesion density of Chlorella vulgaris on hydrophilic glass, and hydrophobic indium tin oxide (ITO) surfaces at constant shear rate. Cultivation of algae as biofilms offers an energy and water efficient method for algal biofuel production. In order to design algal biofilm cultivation systems, algal adhesion and biofilm formation on substrates with different surface properties must be known. To assess this, a parallel plate flow chamber was used to quantify the adhesion rate of the commonly used algae Chlorella vulgaris to the surfaces under controlled shear rates. The contact angle and zeta potential measurements were made both for the algal cells and the adhesion surfaces to model adhesion. The experimental results were compared with the predictions of the Derjaguin, Landau, Verwey, Overbeek (DLVO), extended DLVO (XDLVO) theories, and the thermodynamic model. The experiments showed that the rate of adhesion over the hydrophobic surface was 81 cells mm−2min−1 which was 3 times larger than that of the hydrophilic surface for the first forty minutes of the adhesion experiments. Moreover, the final adhesion density over the hydrophobic surface was 6182 mm−2 after an experimental duration of 320 minutes which was 2.7 times that of the hydrophilic surface. Detachment studies done with increased shear rates showed that the adhesion strength of algae was also higher over the hydrophobic surface. The experimental results fit best with the results from the XDLVO theory. However, the model was inaccurate in predicting high detachment rate from the hydrophilic surface with increased shear rates. Results show the importance of surface material selection for the initial adhesion of cells. These results can be used for selection and design of surface materials for optimizing initial adhesion of algae cells in algal biofilm photobioreactors. Furthermore, the results can also be used for the design of planktonic photobioreactors to avoid biofouling.
Convective Heat Transfer Enhancement on a Channel Wall With a High Frequency, Oscillating Agitator
Authors: Yeom Taiho , Simon Terrence W. , Yu Youmin , North Mark T. , Cui Tianhong
Published: August 2012

Convective heat transfer enhancement on a wall of a narrow channel enhanced by high-frequency, translational oscillation of a thin agitator plate is described. The oscillation is realized using a piezoelectric stack actuator. Small amplitudes of the piezoelectric stack actuator were amplified through oval loop shell structures so that large translational amplitudes are provided to the thin plate agitator. Heat transfer tests were conducted with three operating frequencies resulting from three oval loop shell structures operating at their resonance frequencies. For each operating frequency, four different amplitudes (corresponding to different applied voltages to the piezoelectric stacks) were investigated. Three channel flow rates were tested. They represent laminar, transition, and turbulent flow regimes for a non-agitated channel. Running with agitation and channel flow allows a study of the agitation effect with different channel flow rates. The results show that the oscillating plate with a frequency of about 1,140 Hz raises the convective heat transfer coefficient on the heated surface by 93%, compared to a case with channel flow only. The flow rate was 45 LPM, corresponding to the transitional flow regime in an un-agitated channel. The amplitude of oscillation was about 1.1 mm, peak-to-peak. It was found that the effect of cross flow is minimized with high oscillation frequency agitation regardless of channel flow velocity and flow regime of the un-agitated flow. In addition, numerical simulations were performed to support the experimental results and understand underlying phenomena of translational agitation. Numerical simulation results match well with the experiments and provided good explanations of heat transfer enhancement from the translational agitator. The piezoelectrically-driven oscillating agitator plate coupled with traditional fan cooling shows promising potential for advanced air cooling applications.
An In Situ Mechanism for the Optimal Cooling of Oil-Lubricated Rolling Element Bearings and Planetary Gear Systems
Authors: Wornyoh E. Y. A. , Patel D. K. , Schuessler L. D.
Published: August 2012

A major detriment to reliable and sustainable operation of rotational equipment has been extensively linked to high thermal loads from frictional dissipation. Frictional dissipation in critical tribological components such as bearings and gears results in lubricant degradation and subsequent subpar thermal performance. In this study, a novel in situ lubricant cooling system is used to provide a continuous cooling of these critical tribo-components. Experiments were conducted using rolling element bearing (REB) and planetary gear system (PGS) sets. The stationary outer race of a REB was used to accommodate a cooling coil in a heat exchange-like arrangement. Similarly, the stationary outer ring of the PGS housed a cooling coil in another heat exchanger-like arrangement. Use of the heat exchanger arrangements assured continuous in situ cooling to remove the heat generated in the tribological REB and PGS. Water was used as the coolant while Amsoil 75W-90 Severe Gear® oil was the lubricant used. Highly conductive copper coils surrounded the REB or PGS and the coolant was circulated through the coils to remove the heat from the outer bearing race and ring gear. The hot lubricant rejects heat by convection into the outer race thereby limiting lubricant degradation. The incidence of wear and premature failure are also minimized. So far results from this experimental study show that heat generation is significantly minimized in bearings and gears when cooled in situ. This preliminary study has offered important insight for more rigorous follow-on studies.
Shock Wave Propagation as a Mechanism of Injury in Nonlinear Viscoelastic Soft Tissues
Authors: Laksari Kaveh , Shafieian Mehdi , Darvish Kurosh , Sadeghipour Keyanoush
Published: August 2012

This study investigates the propagation of shock waves and self-preserving waves in soft tissues such as brain as a mechanism of injury in high rate loading conditions as seen in blast-induced neurotrauma (BINT). The derived mathematical models indicate that whereas linear viscoelastic models predict only decaying waves, instances of such phenomena as shock can be achieved in nonlinear media. In this study, a nonlinear viscoelastic material model for brain tissue was developed in compression. Furthermore, nonlinear viscoelastic wave propagation in brain tissue was studied and a criterion for the development of shock waves was formulated. It was shown that discontinuities in the acceleration that happen in blast loading conditions may evolve to shock waves, resulting in large discontinuities in strain and stress at the wave front leading to tissue injuries.
Quantifying Thermal Transport of High-Temperature Ceramics From First Principle Calculations
Authors: Kouchmeshky Babak , Kroll Peter
Published: August 2012

We provide virtual testing capabilities of materials at temperatures where actual testing encounters many and severe technical difficulties. Combining ab-initio molecular dynamics simulation and kinetic theory we compute and analyze thermal transport of refractory ceramics at (ultra-) high temperatures ranging from 1000K to 2200 K. Most of our results are agreeable with available experimental data, though we find and examine discrepancies in selected cases. Our approach also catches the anisotropic behavior in thermal transport of some (single crystalline) materials. Since contributions of individual phonon modes on thermal transport are quantified, we suggest avenues for control and design of thermal conductivity in these materials.
Droplet Shapes on Superhydrophobic Surfaces Under Electrowetting Actuation
Authors: Annapragada S. Ravi , Murthy Jayathi Y. , Garimella Suresh V.
Published: August 2012

Droplet behavior on structured surfaces has recently generated a lot of interest due to its application to self-cleaning surfaces and in microfluidic devices. In this paper, the droplet shape and the droplet state on superhydrophobic surfaces are predicted using the Volume of Fluid (VOF) approach. Various structured surfaces are considered and the apparent contact angles are extracted from the predicted droplet shapes. Droplet dynamics under electrowetting are also modeled, including contact line friction. The model is validated against in-house experiments and experiments from the literature. The droplet state, droplet shape and apparent contact angles match well with the experimental measurements. The Cassie and Wenzel states on structured surfaces are also accurately predicted. Further, the electrowetting-induced transition from the Cassie to the Wenzel state and the reversal to the Cassie state is predicted for two different superhydrophobic surfaces. The transient wetting process, intermediate energy states and droplet shapes during electrowetting are simulated. The effective contact line friction coefficient on pillared surfaces is predicted to be 0.14 Ns/m2, consistent with published values.
Numerical Model for Storage Systems Based on Phase-Change Materials
Authors: Sciacovelli Adriano , Verda Vittorio , Colella Francesco
Published: August 2012

Phase-change materials (PCM) are particularly promising for thermal storage in various energy plants as solar plants, district heating, heat pumps, etc. mainly because of the possibility to reduce the volume of storage tanks, but also because the problems related with thermal stratification are considerably reduced. On the other hand, research is necessary in order to address technical problems, mainly related to the heat transfer in the medium, which needs to be enhanced in order to achieve reasonable charging and discharging processes. The present paper describes the application of computational fluid-dynamics (CFD) for the analysis of PCM thermal storage systems. The numerical analysis is directed at understanding the role of buoyancy-driven convection during constrained solidification and melting inside a shell-and-tube geometry. The 2D model is based on a finite-volume numerical procedure that adopts the enthalpy method to take in account the phase change phenomenon. The time-dependent simulations show the melting phase front and melting fraction of the PCM and incorporate the fluid flow in the liquid phase. The obtained temperature profiles are compared to a set of experimental data available in the literature. The results show that during the melting process natural convection within the PCM has non negligible effects on the behavior of the system. The numerical simulations of the solidification process show that the increasing solid fraction of the PCM inhibits the buoyancy in the remaining liquid portion of the phase-change-material. Furthermore, the paper discusses the effects on the phase-change processes of the main operating conditions, including inlet temperature and mass flow rate of the heat transfer fluid.
Effect of Indoor Air Ventilation on Particulate Pollutant Concentration Distribution, Including Nucleation, Coagulation and Surface Growth
Authors: Tavakoli Behtash , Ahmadi Goodarz
Published: August 2012

Typical furniture inside residential or office buildings is made from materials that emit terpenes. Terpenes react with ozone in the air, and produce secondary organic aerosols (SOA). During summer the concentration of SOAs may exceed by a factor of two to five times the concentration in outdoor air. The high concentration of SOA could adversely influence the human health. The air ventilation inside the room as well as the particles’ Brownian motion causes the particles to mix and coagulate. The coagulation of SOAs due to their collision leads to an increase in sizes in time. Coagulation, surface growth and nucleation of particles are the mechanisms which change the particle size and concentration distribution. The particle size distribution is important as large particles sediment rapidly and they are not a health threat for residents while fine and ultra fine particles stay suspended in the air and could enter the human respiratory system. A typical office room with furniture and a manikin was modeled in this study. The indoor airflow was simulated and was followed by the analysis of dispersion and coagulation of particles using the moment method. Two types of ventilation systems were modeled, and the results were compared discussed.
Comparison of Lithium-Ion Battery Cathode Materials and the Internal Stress Development
Authors: Wang Yixu , Huang Hsiao-Ying Shadow
Published: August 2012

The need for development and deployment of reliable and efficient energy storage devices, such as lithium-ion rechargeable batteries, is becoming increasingly important due to the scarcity of petroleum. Lithium-ion batteries operate via an electrochemical process in which lithium ions are shuttled between cathode and anode while electrons flowing through an external wire to form an electrical circuit. The study showed that the development of lithium-iron-phosphate (LiFePO4) batteries promises an alternative to conventional lithium-ion batteries, with their potential for high energy capacity and power density, improved safety, and reduced cost. However, current prototype LiFePO4 batteries have been reported to lose capacity over ∼3000 charge/discharge cycles or degrade rapidly under high discharging rate. In this study, we report that the mechanical and structural failures are attributed to dislocations formations. Analytical models and crystal visualizations provide details to further understand the stress development due to lithium movements during charging or discharging. This study contributes to the fundamental understanding of the mechanisms of capacity loss in lithium-ion battery materials and helps the design of better rechargeable batteries, and thus leads to economic and environmental benefits.
Phase Field Method for Simulation of Multiphase Flow
Authors: Ganapathy Harish , Al-Hajri Ebrahim , Ohadi Michael M.
Published: August 2012

The present paper reports a comprehensive study on the numerical simulation of Taylor flow in microchannels by the phase field method. Additionally, a comparative study was also performed against an alternative volume of fluid model based on which the phase field method was found to be more advantageous in key aspects such as the absence of unphysical interfacial pressure oscillations and the ability to account for variations in the surface tension force and thus predict several bubble lengths under constant flow conditions while observing the physics of homogeneous two-phase flow. Different bubble formation mechanisms were simulated and compared against experimental findings in literature. The simulation of a thin liquid film at the channel wall was found to be a limitation of most works pertaining to Taylor flow, including the present. This was ascribed to be more likely due to limited dimensional and spatial resolution as well as inaccurate contact angle dynamics rather than limitations of the modeling approach itself. The effect of wall adhesion was studied with respect to the flow and pressure field in the channel. A validation of the model was achieved through a favorable comparison of the numerically predicted gas void fraction and bubble lengths with existing models and correlations. On the whole, the phase field method was concluded to have improved predictive accuracy with respect to certain aspects as compared to conventional multiphase flow models.
Technical Note: Comparison between single and multiview simulated DXA configurations for reconstructing the 3D shape and bone mineral density distribution of the proximal femur
Authors: Humbert Ludovic , Whitmarsh Tristan , de Craene Mathieu , del Río Barquero Luis Miguel , Frangi Alejandro F.
Published: August 2012

Purpose:

Dual‐energy x‐ray absorptiometry (DXA) is used in clinical routine to provide a two‐dimensional (2D) analysis of the bone mineral density (BMD). 3D reconstruction methods from 2D DXA images could improve the BMD analysis. To find the optimal configuration that should be used in clinical routine, this paper relies on a 3D reconstruction method from DXA images to compare the accuracy that can be obtained from one single‐view and from multiview DXA images (two to four projections).

Methods:

The 3D reconstruction method uses a statistical model and a nonrigid registration technique to recover in 3D the shape and the BMD distribution of the proximal femur. The accuracy was evaluatedin vivo by comparing 3D reconstructions obtained from simulated DXA images of 30 patients (using between one and four DXA views) with quantitative computed tomography reconstructions.

Results:

This comparison showed that the use of one single DXA provides accurate 3D reconstructions (mean shape accuracy of 1.0 mm and BMD distribution errors of 7.0%). Among the multiview configurations, the use of two views (0° and 45°) was the best compromise, increasing the accuracy of pose (mean accuracy of 0.7°/1.2°/0.9° against 1.0°/3.5°/3.3° for the single view), reducing slightly the BMD errors (5.7%) while maintaining the same shape accuracy.

Conclusions:

The use of two views constitutes an interesting configuration when multiview DXA devices are available in clinical routine. However, the use of only one single view remains an accurate solution to recover the shape and the BMD distribution in 3D, with the advantage of a higher potential for clinical translation.
Aerosols from Overseas Rival Domestic Emissions over North America
Authors: Yu Hongbin , Remer Lorraine A. , Chin Mian , Bian Huisheng , Tan Qian , Yuan Tianle , Zhang Yan
Published: August 2012

Particles Without Borders

Aerosols have important and often adverse impacts on atmospheric composition, air quality, and climate. However, aerosols can be transported long distances, limiting the efficacy of local regulations.

Yu
et al.

(p.
566
) used satellite data to estimate how much of the aerosol load in the atmosphere above North America originates overseas. Approximately half of the dust and pollution over North America comes from Asia, Europe, Africa, and the Middle East. Asian dust is the largest fraction of this total. Furthermore, potential increases in dust emissions in response to climate change might overwhelm any reductions in pollution from emerging Asian economies.
Opening and Closing of the Bacterial RNA Polymerase Clamp
Authors: Chakraborty Anirban , Wang Dongye , Ebright Yon W. , Korlann You , Kortkhonjia Ekaterine , Kim Taiho , Chowdhury Saikat , Wigneshweraraj Sivaramesh , Irschik Herbert , Jansen Rolf , Nixon B. Tracy , Knight Jennifer , Weiss Shimon , Ebright Richard H.
Published: August 2012

Clamping Down

Crystal structures of RNA polymerase show that a “clamp” region which surrounds the DNA binding site can adopt conformations ranging from a closed to an open state.

Chakraborty
et al.

(p.
591
) used single-molecule fluorescence energy transfer experiments to detect the clamp's conformational changes in solution during the transcription cycle. The results support a model in which a clamp opening allows DNA to be loaded into the active-center cleft and unwound. Direct interactions with DNA likely trigger clamp closure upon formation of a catalytically competent transcription initiation complex.
Transformation Optics and Subwavelength Control of Light
Authors: Pendry J. B. , Aubry A. , Smith D. R. , Maier S. A.
Published: August 2012

Transforming Optical Transformations

Recent developments in optics and materials have seen interactions between light and matter move to the subwavelength regime.

Pendry
et al.

(p.
549
) review how transformation optics has provided a general platform for controlling and manipulating light, literally transforming the field of optics. The coordinate system that the electric and magnetic components of the light field “feel” can be transformed through materials design by giving rise to exotic optical phenomena such as cloaking, negative refraction, and energy harvesting.
Unraveling the Life History of Successful Invaders
Authors: Sol Daniel , Maspons Joan , Vall-llosera Miquel , Bartomeus Ignasi , García-Peña Gabriel E. , Piñol Josep , Freckleton Robert P.
Published: August 2012

Successful Invaders

Invasive species have been integrated into ecosystems worldwide, and in many cases can cause significant ecological and economic damage. Not all non-native species, however, become invasive species; thus there has been much effort put toward understanding what makes a non-native “colonizer” an invader. It has been thought that, in general, successful invaders tend to be those that produce a large amount of offspring over a very short period of time, however, this pattern is absent in many successful invaders.

Sol
et al.

(p.
580
) looked at over 2700 invasions by bird species across the world and found no relationship between population growth rate and invasion success, although rapidly reproducing species could have an advantage when the new environment resembled their native environment. Furthermore, in many cases, those species that could prioritize survival, and delay reproduction, were much more successful than those forced to reproduce regardless of environmental conditions.
Quantum Mechanics of Black Holes
Authors: Witten Edward
Published: August 2012

The popular conception of black holes reflects the behavior of the massive black holes found by astronomers and described by classical general relativity. These objects swallow up whatever comes near and emit nothing. Physicists who have tried to understand the behavior of black holes from a quantum mechanical point of view, however, have arrived at quite a different picture. The difference is analogous to the difference between thermodynamics and statistical mechanics. The thermodynamic description is a good approximation for a macroscopic system, but statistical mechanics describes what one will see if one looks more closely.
Stellar-Mass Black Holes and Ultraluminous X-ray Sources
Authors: Fender Rob , Belloni Tomaso
Published: August 2012

We review the likely population, observational properties, and broad implications of stellar-mass black holes and ultraluminous x-ray sources. We focus on the clear empirical rules connecting accretion and outflow that have been established for stellar-mass black holes in binary systems in the past decade and a half. These patterns of behavior are probably the keys that will allow us to understand black hole feedback on the largest scales over cosmological time scales.
Left and Right, Right and Wrong
The Righteous Mind
Why Good People Are Divided by Politics and Religion

by Jonathan Haidt

Pantheon, New York, 2012. 441 pp. $28.95, C$33. ISBN 9780307377906. Allen Lane, London. £20. ISBN 9781846141812.
Authors: Jost John T.
Published: August 2012

Haidt offers a provocative account of the psychological foundations of morality and how they lead to political conflicts.
A 200-Second Quasi-Periodicity After the Tidal Disruption of a Star by a Dormant Black Hole
Authors: Reis R. C. , Miller J. M. , Reynolds M. T. , Gültekin K. , Maitra D. , King A. L. , Strohmayer T. E.
Published: August 2012

Oscillating Black Hole

The massive black holes that reside in the centers of galaxies can occasionally capture and tidally disrupt stars that wander too close. One such tidal disruption event was detected last year by the Swift satellite. Follow-up x-ray observations analyzed by

Reis
et al.

(p.
949
, published online 2 August; see the Perspective by

McKinney

) show quasi-periodic oscillations that suggest that an accretion disk formed around the black hole shortly after the tidal disruption event. This type of oscillation is commonly seen in the x-ray light from the much lighter black holes that result from the gravitational collapse of stars, but has been seen only once in a massive black hole residing in the center of a galaxy.
Lineage Tracing Reveals Lgr5
+
Stem Cell Activity in Mouse Intestinal Adenomas
Authors: Schepers Arnout G. , Snippert Hugo J. , Stange Daniel E. , van den Born Maaike , van Es Johan H. , van de Wetering Marc , Clevers Hans
Published: August 2012

Cancer Stem Cells in Color

One of the liveliest debates in contemporary cancer research centers on whether cancer stem cells (CSCs) exist and, if so, how these cells are defined phenotypically. CSCs are hypothesized to be a small population of cells within a tumor that are endowed with the unique capacity to drive tumor growth—a scenario that in principle would offer important therapeutic opportunities. By studying mice expressing multicolor reporter genes,

Schepers
et al.

(p.
730
, published online 1 August) were able to visualize and monitor the fate of a candidate stem cell for intestinal adenomas, an early stage of cancer. This “lineage tracing” analysis suggests that tumor cells expressing the intestinal crypt stem cell marker Lgr5 (leucine-rich repeat containing G protein–coupled receptor 5) are the cells that fuel the growth of intestinal adenomas.
Classical Black Holes: The Nonlinear Dynamics of Curved Spacetime
Authors: Thorne Kip S.
Published: August 2012

Numerical simulations have revealed two types of physical structures, made from curved spacetime, that are attached to black holes: tendexes, which stretch or squeeze anything they encounter, and vortexes, which twist adjacent inertial frames relative to each other. When black holes collide, their tendexes and vortexes interact and oscillate (a form of nonlinear dynamics of curved spacetime). These oscillations generate gravitational waves, which can give kicks up to 4000 kilometers per second to the merged black hole. The gravitational waves encode details of the spacetime dynamics and will soon be observed and studied by the Laser Interferometer Gravitational Wave Observatory and its international partners.
On Our Biocultural Nature
Race, Monogamy, and Other Lies They Told You
Busting Myths About Human Nature

by Agustín Fuentes

University of California Press, Berkeley, 2012. 290 pp. $27.50, £19.95. ISBN 9780520269712.
Authors: Jenkins Antoinette
Published: August 2012

Fuentes dissects various widely held but scientifically unsupported beliefs about human sex, aggression, and race.
F. Herbert Bormann (1922–2012)
Authors: Hedin Lars O.
Published: August 2012

An ecologist's relentless focus on large-scale studies of watersheds played a key role in identifying human impacts on forests.
Outsourcing Genome Protection
Authors: Xiol Jordi , Pillai Ramesh S.
Published: August 2012

Small RNAs repress transposons by triggering the formation of another class of small RNAs that silence transposon targets.