bluuebunny/crossref_metadata_2025 huggingface dataset:
Does a text messaging intervention improve knowledge, attitudes and practice regarding iodine deficiency and iodized salt consumption?
Authors: Mehran Ladan , Nazeri Pantea , Delshad Hossein , Mirmiran Parvin , Mehrabi Yadollah , Azizi Fereidoun
Published: July 2012

Objective

To determine the effectiveness of implementation of a prevention programme via mobile phone text messaging in enhancing knowledge, attitudes and practice concerning iodine deficiency and iodized salt consumption.

Design

In a randomized controlled trial, participants were subjected to a brief tele-educational support regarding iodine deficiency and the importance of iodized salt consumption. The intervention group received daily text messages via mobile phone for 6 weeks. Knowledge, attitude and practice scores, urinary iodine concentration and salt iodine content were assessed at baseline and 8 weeks after the intervention.

Setting

Participants were recruited from health-care centres in Tehran, the capital city of Iran.

Subjects

For the present study 205 females aged ≥18 years were randomly assigned to the intervention (n 95) and control (n 110) groups.

Results

A significant difference was found in median knowledge scores between the intervention and control groups at follow-up (P = 0·004). There was also a significant difference in median attitude scores between the intervention and control groups (P = 0·02). The intervention group did not differ significantly in median practice score, urinary iodine concentration and salt iodine content from the control group.

Conclusions

Text messaging interventions are effective in improving individuals’ knowledge and attitudes regarding preventive health-care topics.
Convergent validity of the International Physical Activity Questionnaire (IPAQ): meta-analysis
Authors: Kim Youngdeok , Park Ilhyeok , Kang Minsoo
Published: July 2012

Objective

The purpose of the present study was to use a meta-analytic approach to examine the convergent validity of the International Physical Activity Questionnaire (IPAQ).

Design

Systematic review by meta-analysis.

Setting

The relevant studies were surveyed from five electronic databases. Primary outcomes of interest were the product-moment correlation coefficients between IPAQ and other instruments. Five separate meta-analyses were performed for each physical activity (PA) category of IPAQ: walking, moderate PA (MPA), total moderate PA (TMPA), vigorous PA (VPA) and total PA (TPA). The corrected mean effect size (ESρ) unaffected by statistical artefacts (i.e. sampling error and reliability) was calculated for each PA category. Selected moderator variables were length of IPAQ (i.e. short and long form), reference period (i.e. last 7 d and usual week), mode of administration (i.e. interviewer and self-reported), language (i.e. English and translated) and instruments (i.e. accelerometer, pedometer and subjective measure).

Subjects

A total of 152 ESρ across five PA categories were retrieved from twenty-one studies.

Results

The results showed small- to medium-sized ESρ (0·27–0·49). The highest value was observed in VPA while the lowest value was found in MPA. The ESρ were differentiated by some of the moderator variables across PA categories.

Conclusions

The study shows the overall convergent validity of IPAQ within each PA category. Some differences in degree of convergent validity across PA categories and moderator variables imply that different research conditions should be taken into account prior to deciding on use of the appropriate type of IPAQ.
Spiritual Capital and Economies of Grace: Redefining the Relationship between Religion and the Welfare State
Authors: Baker Christopher
Published: July 2012

This article traces the trajectory of UK government social policy since World War Two, with particular reference to the shifts in the past 10 to 15 years towards concepts such as multi-level governance, localism, the Third Way and the Big Society. It describes the shifting relationships between institutional religion and the State during that period, tracking the ‘return of faith’ in government policy and social welfare as it seeks to address a number of intractable social and economic issues related to cohesion and inequality, as well as a perceived absence of moral and ethical norms within public life. The article proposes a set of new analytical concepts (based on recent empirical research from the US and the UK) which seek to describe and evaluate this new ‘post-secular’ relationship between faith and government. The article concludes that the new ‘post-welfare’ landscape will continue to play well to the existing strengths and positionalities of religion, faith and spirituality in the UK as the twenty-first century moves into its second decade.
Making markets with active labor market policies: the influence of political parties, welfare state regimes, and economic change on spending on different types of policies
Authors: Nelson Moira
Published: July 2012

Active labor market policies consist of a diverse set of policy tools with which to address joblessness and the degree to which governments invest in various policies as a response to rising unemployment varies widely. Fleshing out the determinants by policy type holds the promise of illuminating more clearly contestation over activation. To this end, this study analyzes the role of partisanship as well as welfare state regimes and the economy on spending patterns. We begin by detailing a theoretical framework for understanding variation in active labor market policies. Bonoli categorizes active labor market policies according to their market orientation and emphasis on human capital investment. In a study of social service reforms, Gingrich explains how all parties employ market-based reforms to empower some groups over others. These theories are then used to derive partisan hypotheses for direct job creation, training, labor market services, and employment incentives. Hypotheses for the four main types of active labor market policies are tested with regression analysis of 22 countries between 1985 and 2008. High spending on direct job creation, a non-market oriented policy type, is marginally significantly higher in the social democratic regime and by left governments prior to the activation turn. Left parties spend significantly more than other parties on training policies and after the activation turn these policies also become a distinct feature of the social democratic welfare state regime. The same trend exists for employment incentives. Center-right parties and those within the Christian democratic regime also spend marginally significantly higher on training policies before the activation turn, which is explained by results for deindustrialization. No partisan or regime effects are found for labor market services, which supports the view that all countries rely on these policies. The literature also suggests that a composite measure masks political conflict since this policy type encompasses diverse policies.
Gravity wave occurrence statistics derived from paired COSMIC/FORMOSAT3 observations
Authors: McDonald A. J.
Published: July 2012

The analysis presented provides statistical information on the occurrence of gravity waves using the dense sampling geometry provided by the COSMIC/FORMOSAT3 constellation. This is achieved by deriving profiles of the gravity wave temperature perturbations from satellite observation and then identifying profile pairs; the magnitude of the cross S‐transform derived from normalized profile pairs is then compared with Monte Carlo simulations to determine whether the same wave can be observed in both profiles. This procedure allows the percentage of paired observations which contain the same wave packet to be derived at a given significance level. This study shows that the occurrence of coherent waves varies strongly as a function of latitude and season. The latitudinal variation observed is demonstrated to be at least partially related to the preferential occurrence of long horizontal wavelength gravity waves at the equator. However, other factors obviously also have an impact, for example seasonal variations in the occurrence in the subtropics seem to be linked to critical level filtering above the subtropical winter jet. The use of the discussed methodology in identifying profile pairs which should be used in the calculation of gravity wave characteristics, such as horizontal wavelength, is also considered. Application of this technique as a quality control step seems to reduce biases introduced into the horizontal wavelength distribution when uncorrelated profile pairs are used to derive phase information. Thus, it is highly recommended to apply some statistical technique to identify profile pairs which include the same wave before applying schemes to derive horizontal wavelength and/or momentum fluxes.
Long‐term trends of hail‐related weather types in an ensemble of regional climate models using a Bayesian approach
Authors: Kapsch M.‐L. , Kunz M. , Vitolo R. , Economou T.
Published: July 2012

This paper investigates the long‐term variability of specific weather types that are associated with damaging hailstorms in Germany for past (1971–2000) and future (2011–2050) time periods. Forty large‐scale weather types are determined by the objective weather type classification scheme of German Weather Service. This scheme is applied to both reanalyses (ERA‐40) and eight different regional climate model (RCM) simulations. It is shown that the RCMs are able to approximately reproduce the distribution of weather type occurrences obtained from the reference of ERA‐40. Using additional insurance loss data, the weather types are further identified as hail‐related or hail‐unrelated. Hailstorms are neither captured comprehensively by existing observation systems nor can they be modeled reliably and the large‐scale weather types are here considered as proxies for hail occurrence. Four weather types that are most likely associated with damaging hailstorms show a slight increase both during the past and future period according to the RCM simulations. A novel statistical model is developed for the probabilistic prediction of the fraction of hail damage days conditional on the weather types. The model is Bayesian and uses a Markov Chain Monte Carlo approach. For the ERA‐40 reanalysis the model prediction agrees well with fraction of hail damage days observed in the insurance data. For most of the RCM projections, the statistical model predicts a slight increase in the number of hail days in the future (2031–2045), with relative changes between 7 and 15% compared to the period 1971–2000.
Understanding North Pacific sea level trends
Authors: Bromirski Peter D. , Miller Arthur J. , Flick Reinhard E.
Published: July 2012

Rising sea level poses significant challenges to infrastructure and populations, particularly for coastal [Heberger et al., 2009] and island communities [Webb and Kench, 2010] in the North Pacific where population density at or near coastal waters is high. A significant portion of the United States' security, commerce, and ecosystem assets are located at or near the coast, making them vulnerable to sea level rise. Although global mean sea level (MSL) rise is a fundamental consideration, regional mean sea level (RSL) height variability within ocean basins and along their boundaries can be more critical, particularly in the North Pacific where the amplitude of inter‐annual variability is high.
Space station astronauts discuss life in space during AGU interview
Authors: Showstack Randy
Published: July 2012

Just one day after China's Shenzhou‐9 capsule, carrying three Chinese astronauts, docked with the Tiangong‐1 space lab on 18 June, Donald Pettit, a NASA astronaut on the International Space Station (ISS), said it is “a step in the right direction” that more people are in space. “Before they launched, there were six people in space,” he said, referring to those on ISS, “and there are 7 billion people on Earth.” The astronauts were “like one in a billion. Now there are nine people in space,” Pettit said during a 19 June interview that he and two other astronauts onboard ISS had with AGU. Pettit continued, “So the gradient of human beings going into space is moving in the right direction. We need to change these numbers so that more and more human beings can call space their home so we can expand off of planet Earth and move out into our solar system.”
Vegetation affects hillslope hydrodynamics
Authors: Balcerak Ernie
Published: July 2012

Hillslopes are an important part of the hydrological cycle because water from rainfall or snowmelt runs downhill to networks of streams. Understanding hillslope hydrological dynamics is important for flood and debris flow prediction. However, because hillslopes are highly varied, developing general frameworks for analyzing them is difficult.Bachmair et al. compared three hillslopes to try to synthesize understanding of subsurface flow processes at the hillslope scale, focusing on the effect of vegetation.
Modeling evolution of the San Andreas Fault system in northern and central California
Authors: Popov Anton A. , Sobolev Stephan V. , Zoback Mark D.
Published: July 2012

We present a three‐dimensional finite element thermomechanical model idealizing the complex deformation processes associated with evolution of the San Andreas Fault system (SAFS) in northern and central California over the past 20 Myr. More specifically, we investigate the mechanisms responsible for the eastward (landward) migration of the San Andreas plate boundary over time, a process that has largely determined the evolution and present structure of SAFS. Two possible mechanisms had been previously suggested. One mechanism suggests that the Pacific plate first cools and captures uprising mantle in the slab window, subsequently causing accretion of the continental crustal blocks. An alternative scenario attributes accretion to the capture of plate fragments (microplates) stalled in the ceased Farallon‐North America subduction zone. Here we test both these scenarios numerically using a recently developed lithospheric‐scale code, SLIM3D, that employs free surface, nonlinear temperature‐ and stress‐dependent elastoviscoplastic rheology and allows for self‐generation of faults. Modeling suggests that microplate capture is the primary driving mechanism for the eastward migration of the plate boundary, while the slab window cooling mechanism alone is incapable of explaining this phenomenon. We also show that the system evolves to the present day structure of SAFS only if the coefficient of friction at mature faults is low (0.08 for the best fit model). Thus, our model provides an independent constraint supporting the “weak fault in a strong crust” hypothesis for SAFS.
Evidence for El Niño–Southern Oscillation (ENSO) influence on Arctic CO interannual variability through biomass burning emissions
Authors: Monks S. A. , Arnold S. R. , Chipperfield M. P.
Published: July 2012

A global chemical transport model is used in conjunction with measurements from surface stations to study the importance of biomass burning and meteorology in driving Arctic carbon monoxide (CO) interannual variability (IAV). Simulations with yearly varying fire emissions capture 66%–93% of CO IAV and a simulation with yearly varying meteorology but fixed fire emissions captures 0–25%, showing that biomass burning variability is the dominant driver of surface CO IAV. Observed CO anomalies are found to be significantly correlated with El Niño (0.58 < r < 0.64, 99% confidence level (CL)) and results indicate that this is due to ENSO's influence on fire emissions. Boreal Alaska, Canada and north‐east Siberia are found to contribute 59% to total Arctic fire CO and 67% to Arctic fire CO IAV. Analysis of meteorological fire drivers in these regions suggests that ENSO affects winter/spring precipitation, driving the Arctic/ENSO relationship.
Evolution of chorus waves and their source electrons during storms driven by corotating interaction regions
Authors: Li Wen , Thorne Richard , Bortnik Jacob , McPherron Robert , Nishimura Yukitoshi , Angelopoulos Vassilis , Richardson Ian G.
Published: July 2012

During Corotating Interaction Region (CIR)‐driven storms, relativistic electron fluxes in the outer radiation belt decrease in the main phase, followed by a gradual increase in the recovery phase. Recent studies have shown that whistler mode chorus waves play an important role in accelerating the seed electron population to relativistic energies in the outer radiation belt. However, the evolution of chorus waves and their source electrons responsible for the wave excitation during storm various phases is not well understood. In this study we select 72 CIR‐driven storm periods over the interval 2007–2011 to perform superposed epoch analysis of the evolution of chorus waves and source electrons in the L* and MLT range extensively observed by THEMIS during various phases of CIR‐driven storms. The wave amplitudes and the occurrence of chorus waves substantially increase and peak in the main phase and gradually decrease in the following recovery phase at L* < ∼7. The phase space density of source electrons at L* < ∼7 also increases in the main phase followed by a gradual decay in the recovery phase, showing a remarkable consistency with the evolution of chorus waves. Importantly, the evolution of the chorus wave activity and source electron population is highly dependent on the preceding interplanetary magnetic field (IMF)Bzorientation. Our results suggest that the increased activity of chorus waves and source electrons may contribute to the enhanced radiation belt electron flux in the recovery phase of CIR‐driven storms, but an additional mechanism is probably required to explain the main phase dropout.
The Stokes drift and wave induced‐mass flux in the North Pacific
Authors: Tamura Hitoshi , Miyazawa Yasumasa , Oey Lie‐Yauw
Published: July 2012

Stokes drift and wave induced‐mass flux in realistic wavefields and ocean currents in the North Pacific Ocean are studied using a third generation wave model with ambient geostrophic currents estimated from satellite altimetry data to directly estimate the Stokes drift for random directional waves. Comparison with in situ buoy data shows that the model performed well in representing the Stokes drift field and total wave momentum. In the North Pacific, the annual mean surface Stokes drift ranges from 2 to 10 cm/s and the mean Stokes e‐folding depth is 1 to 2 m. The Stokes drift fields estimated using bulk wave parameters compare poorly against buoy data, and are shown to overestimate (underestimate) the Stokes e‐folding depth (the surface Stokes drift) computed directly from wave spectra by as much as 5–20 times larger (2–10 times smaller). The spatial distributions of mean wave height and mass transport approximately follow the synoptic scale associated with atmospheric forcing, and the divergence of wave induced‐mass flux is significantly modified by local fetch, the coast and ocean currents. Due to strong wave refraction along the Kuroshio extension, surface vertical velocity induced by Stokes divergence is comparable to the Ekman velocity, and may alter the meso‐scale dynamics of the front.
Evolution of the Yiwulushan metamorphic core complex from distributed to localized deformation and its tectonic implications
Authors: Zhang Bilong , Zhu Guang , Jiang Dazhi , Li Changcheng , Chen Yin
Published: July 2012

The Yiwulushan metamorphic core complex (YSMCC) is situated in the northern part of the eastern North China Craton (NCC) that experienced significant lithospheric thinning in an extensional regime during the Late Mesozoic. We present structural and geochronological evidence to show that the YSMCC underwent NNE‐SSW extension in the Late Jurassic and WNW‐ESE extension in the Early Cretaceous. We show that the YSMCC started with a sub‐horizontal shear zone referred to as the Yiwulushan detachment shear zone (YDSZ) in the Late Jurassic between 157 and 147 Ma with a top‐to‐the‐SSW shear sense. The YDSZ was subjected to limited doming probably toward the end of its formation. The NNE‐striking, WNW‐dipping Waziyu normal shear zone (WZYSZ) was formed along the western margin of the core complex during the Early Cretaceous, and truncates the earlier YDSZ. The whole core complex underwent doming in a rolling‐hinge manner in the end of the latest Early Cretaceous. Thereafter, the YSMCC was overprinted by brittle normal faults along its western margin in the Late Cretaceous. Development of the initially flat‐lying YDSZ is associated with diffuse mid‐crustal flow whereas the formation of the rolling‐hinge type WZYSZ is characterized by localized deformation. The Late Jurassic more diffuse deformation has a rather constant top‐to‐the‐SSW shearing and produced a variety of shear‐related structures such as recumbent isoclinal folds and transposition foliation. The YSMCC evolution also demonstrates that the Late Mesozoic extension along the northern part of the eastern NCC started as early as the Late Jurassic rather than the previously proposed Early Cretaceous.
Coupling hydrodynamic models and value of information for designing stage monitoring networks
Authors: Alfonso Leonardo , Price Roland
Published: July 2012

Because the collection of data in water systems is important for making informed decisions, monitoring networks are designed and installed in such systems. Traditionally, the design of hydrometric monitoring networks has been concentrated on measuring streamflow/precipitation at particular key (gauged) sites so that streamflow/precipitation can be estimated accurately at ungauged sites. Although many methods take into account a set of final users of the information, there appears to be no method that explicitly considers them in the mathematical formulation of the decision‐making process. This paper presents a novel approach for designing monitoring networks in a water system using the concept of value of information (VOI). This concept takes into account three main factors: (1) the belief that the decision maker has about the state of the water system before having any information; (2) the consequences associated with the decision of having to choose among several possible management actions given the state of the water system; and (3) the evaluation and update of new information when it becomes available. The methodology uses a water level time series generated by a hydrodynamic model at every computational point, each one being a potential monitor site. The method is tested in a polder system in the Netherlands, where monitoring is required to make informed decisions about the operation of a set of hydraulic structures to reduce flood impacts.
Anticipating, complete and lag synchronizations in RC phase-shift network based coupled Chua’s circuits without delay
Authors: Srinivasan K. , Senthilkumar D. V. , Raja Mohamed I. , Murali K. , Lakshmanan M. , Kurths J.
Published: July 2012

We construct a new RC phase shift network based Chua’s circuit, which exhibits a period-doubling bifurcation route to chaos. Using coupled versions of such a phase-shift network based Chua’s oscillators, we describe a new method for achieving complete synchronization (CS), approximate lag synchronization (LS), and approximate anticipating synchronization (AS) without delay or parameter mismatch. Employing the Pecora and Carroll approach, chaos synchronization is achieved in coupled chaotic oscillators, where the drive system variables control the response system. As a result, AS or LS or CS is demonstrated without using a variable delay line both experimentally and numerically.
Spectrally selective ultra-high temperature ceramic absorbers for high-temperature solar plants
Authors: Sani Elisa , Mercatelli Luca , Sansoni Paola , Silvestroni Laura , Sciti Diletta
Published: July 2012

Ultra-high temperature ceramics are the ideal materials for extreme conditions owing to their very high melting points and good thermo-mechanical properties at high temperatures. For these reasons, they are widely known as materials for aerospace applications. This paper presents a comparative spectral characterization of zirconium, hafnium, and tantalum carbides ultra-high temperature ceramics for concentrating solar power applications. Room-temperature reflectance spectra have been measured from the ultraviolet wavelength region to the mid-infrared band. Using these spectral properties, the ceramics were evaluated as sunlight absorbers in receivers for high-temperature thermodynamic solar plants.
Route to chaos for combustion instability in ducted laminar premixed flames
Authors: Kabiraj Lipika , Saurabh Aditya , Wahi Pankaj , Sujith R. I.
Published: July 2012

Complex thermoacoustic oscillations are observed experimentally in a simple laboratory combustor that burns lean premixed fuel-air mixture, as a result of nonlinear interaction between the acoustic field and the combustion processes. The application of nonlinear time series analysis, particularly techniques based on phase space reconstruction from acquired pressure data, reveals rich dynamical behavior and the existence of several complex states. A route to chaos for thermoacoustic instability is established experimentally for the first time. We show that, as the location of the heat source is gradually varied, self-excited periodic thermoacoustic oscillations undergo transition to chaos via the Ruelle-Takens scenario.
Aeroacoustic power generated by multiple compact axisymmetric cavities: Effect of hydrodynamic interference on the sound production
Authors: Nakiboğlu G. , Hirschberg A.
Published: July 2012

Aeroacoustic sound generation due to self-sustained oscillations by a series of compact axisymmetric cavities exposed to a grazing flow is studied both experimentally and numerically. The driving feedback is produced by the velocity fluctuations resulting from a coupling of vortex sheddings at the upstream cavity edges with acoustic standing waves in the coaxial pipe. When the cavities are separated sufficiently from each other, the whistling behavior of the complete system can be determined from the individual contribution of each cavity. When the cavities are placed close to each other there is a strong hydrodynamic interference between the cavities which affects both the peak amplitude attained during whistling and the corresponding Strouhal number. This hydrodynamic interference is captured successfully by the proposed numerical method.
Quality improvement of ZnO thin layers overgrown on Si(100) substrates at room temperature by nitridation pretreatment
Authors: Wang Peng , Jin Changlian , Wu Xuefeng , Zhan Huahan , Zhou Yinghui , Wang Huiqiong , Kang Junyong
Published: July 2012

To improve the quality of ZnO thin film overgrown on Si(100) substrate at RT (room temperature), the Si(100) surface was pretreated with different methods. The influence of interface on the overgrown ZnO layers was investigated by atomic force microscopy, photoluminescence and X-ray diffraction. We found that the nitridation pretreatment could significantly improve the quality of RT ZnO thin film through two-fold effects: one was to buffer the big lattice mismatch and ease the stress resulted from heterojunction growth; the other was to balance the interface charge, block the symmetric inheritance from the cubic Si (100) substrate and thus restrain the formation of zincblende phase.
Excitation of electromagnetic waves by a pulsed loop antenna in a magnetoplasma
Authors: Kudrin Alexander V. , Shmeleva Natalya M. , Ferencz Orsolya E. , Zaboronkova Tatyana M.
Published: July 2012

A study is made of the radiation from a pulsed loop antenna immersed in a cold collisionless magnetoplasma. Using a rigorous solution for the total field of such an antenna, the energy characteristics of its radiation are determined. The radiated energy and its distribution over the spatial and frequency spectra of the excited waves are analyzed as functions of the antenna and plasma parameters. Numerical results referring to the case where the frequency spectrum of the antenna current is concentrated in the whistler frequency range are reported. The results obtained can be useful in understanding the basic features of wave excitation by pulsed sources in a magnetoplasma.
Electrometric direct current I/V converter with wide bandwidth
Authors: Holt S. , Skyba P.
Published: July 2012

A principle of operation and electrical characteristics of a high frequency current-to-voltage (I/V) converter are presented. The I/V converter measures the electric current with selectable gains of 105, 104, and 103 V/A in the frequency range from DC to 500 kHz, 1.2 MHz, and 2.4 MHz, respectively. These properties make this I/V converter suitable for wide range of applications such as tuning forks, torsion oscillators, ultrasound transducers measurements, detection of the piezoelectric transducers used in STM techniques, etc., in low temperature physics. The influence of the input impedance of a I/V converter on the precision of alternating current measurements is also discussed.
Dynamic mode decomposition analysis of detonation waves
Authors: Massa L. , Kumar R. , Ravindran P.
Published: July 2012

Dynamic mode decomposition is applied to study the self-excited fluctuations supported by transversely unstable detonations. The focus of this study is on the stability of the limit cycle solutions and their response to forcing. Floquet analysis of the unforced conditions reveals that the least stable perturbations are almost subharmonic with ratio between global mode and fundamental frequency λi/ωf = 0.47. This suggests the emergence of period doubling modes as the route to chaos observed in larger systems. The response to forcing is analyzed in terms of the coherency of the four fundamental energy modes: acoustic, entropic, kinetic, and chemical. Results of the modal decomposition suggest that the self-excited oscillations are quite insensitive to vortical forcing, and maintain their coherency up to a forcing turbulent Mach number of 0.3.
Measurements of gas/oil free surface deformation caused by parallel gas flow
Authors: Matsunaga T. , Mialdun A. , Nishino K. , Shevtsova V.
Published: July 2012

Flow-induced dynamic free-surface deformations are experimentally studied in a confined liquid volume of 5cSt silicone oil (Prandtl number Pr = 68). The geometry of the problem is a liquid column concentrically surrounded by an annular gas channel. A gas stream entering the duct from the top or bottom entrains the motionless liquid. The dynamic deformation of the gas–liquid interface is caused by a steady axisymmetric shear-driven flow. The experiments are performed in normal gravity conditions and the static deformation of a liquid bridge interface is unavoidable. The magnitude and shape of the dynamic surface deformation are analyzed using optical measurements with a comprehensive treatment of the images. The deviation of the free surface shape from the corresponding equilibrium profile is determined with an uncertainty of about 0.1 μm. The order of magnitude of the interface deformation is proportional to the capillary number, which is defined as the ratio of the viscous force per unit area to the capillary pressure. The study is performed for a large range of volumes and aspect ratios as well as for different gas velocities. As a general trend, the dynamic deformation grows with the gas velocity, which plays the role of a driving force, but a linear dependence is not observed for all volume ratios, despite the small Reynolds numbers, 280 < Reg < 560. The dynamic deformation displays a strong dependence on the liquid volume ratio and the direction of the gas stream parallel to the interface. When the gas flow is directed against gravity, the largest interface deformations are observed at the smallest volumes among the analyzed ones. In contrast, when the gas stream is aligned with gravity, then the deformations decrease with a decrease in the volume ratio, at a certain value attaining zero (vanishing) and then changing sign.
Observation of magnetic fluctuations and rapid density decay of magnetospheric plasma in Ring Trap 1
Authors: Saitoh H. , Yoshida Z. , Morikawa J. , Yano Y. , Mikami H. , Kasaoka N. , Sakamoto W.
Published: July 2012

The Ring Trap 1 device, a magnetospheric configuration generated by a levitated dipole field magnet, has created high-β (local β ∼ 70%) plasma by using electron cyclotron resonance heating (ECH). When a large population of energetic electrons is generated at low neutral gas pressure operation, high frequency magnetic fluctuations are observed. When the fluctuations are strongly excited, rapid loss of plasma was simultaneously observed especially in a quiet decay phase after the ECH microwave power is turned off. Although the plasma is confined in a strongly inhomogeneous dipole field configuration, the frequency spectra of the fluctuations have sharp frequency peaks, implying spatially localized sources of the fluctuations. The fluctuations are stabilized by decreasing the hot electron component below approximately 40%, realizing stable high-β confinement.
Real-time inverse hysteresis compensation of piezoelectric actuators with a modified Prandtl-Ishlinskii model
Authors: Gu Guo-Ying , Yang Mei-Ju , Zhu Li-Min
Published: July 2012

This paper presents a novel real-time inverse hysteresis compensation method for piezoelectric actuators exhibiting asymmetric hysteresis effect. The proposed method directly utilizes a modified Prandtl-Ishlinskii hysteresis model to characterize the inverse hysteresis effect of piezoelectric actuators. The hysteresis model is then cascaded in the feedforward path for hysteresis cancellation. It avoids the complex and difficult mathematical procedure for constructing an inversion of the hysteresis model. For the purpose of validation, an experimental platform is established. To identify the model parameters, an adaptive particle swarm optimization algorithm is adopted. Based on the identified model parameters, a real-time feedforward controller is implemented for fast hysteresis compensation. Finally, tests are conducted with various kinds of trajectories. The experimental results show that the tracking errors caused by the hysteresis effect are reduced by about 90%, which clearly demonstrates the effectiveness of the proposed inverse compensation method with the modified Prandtl-Ishlinskii model.
An accurate system for onsite calibration of electronic transformers with digital output
Authors: Zhi Zhang , Li Hong-Bin
Published: July 2012

Calibration systems with digital output are used to replace conventional calibration systems because of principle diversity and characteristics of digital output of electronic transformers. But precision and unpredictable stability limit their onsite application even development. So fully considering the factors influencing accuracy of calibration system and employing simple but reliable structure, an all-digital calibration system with digital output is proposed in this paper. In complicated calibration environments, precision and dynamic range are guaranteed by A/D converter with 24-bit resolution, synchronization error limit is nanosecond by using the novelty synchronization method. In addition, an error correction algorithm based on the differential method by using two-order Hanning convolution window has good inhibition of frequency fluctuation and inter-harmonics interference. To verify the effectiveness, error calibration was carried out in the State Grid Electric Power Research Institute of China and results show that the proposed system can reach the precision class up to 0.05. Actual onsite calibration shows that the system has high accuracy, and is easy to operate with satisfactory stability.
Etch induced microwave losses in titanium nitride superconducting resonators
Authors: Sandberg Martin , Vissers Michael R. , Kline Jeffrey S. , Weides Martin , Gao Jiansong , Wisbey David S. , Pappas David P.
Published: July 2012

We have investigated the correlation between the microwave loss and patterning method for coplanar waveguide titanium nitride resonators fabricated on silicon wafers. Three different methods were investigated: fluorine- and chlorine-based reactive ion etches and an argon-ion mill. At high microwave probe powers, the reactive etched resonators showed low internal loss, whereas the ion-milled samples showed dramatically higher loss. At single-photon powers, we found that the fluorine-etched resonators exhibited substantially lower loss than the chlorine-etched ones. We interpret the results by use of numerically calculated filling factors and find that the silicon surface exhibits a higher loss when chlorine-etched than when fluorine-etched. We also find from microscopy that re-deposition of silicon onto the photoresist and side walls is the probable cause for the high loss observed for the ion-milled resonators.
Role of stable modes in zonal flow regulated turbulence
Authors: Makwana K. D. , Terry P. W. , Kim J.-H.
Published: July 2012

Zonal flows are shown to regulate ion temperature gradient turbulence by enabling efficient energy transfer from the instability to a damped eigenmode in the unstable wavenumber range. The damped mode also saturates turbulence when zonal flows are not active in saturation dynamics, for example, in electron temperature gradient turbulence, but the transfer from unstable to stable mode is less efficient and requires a larger amplitude to balance the instability drive. From numerical solutions of a fluid model with a single damped eigenmode, an eigenmode decomposition of the nonlinear evolution shows that the dominant energy transfer involves the triplet correlation of the unstable mode, the zonal flow, and the stable mode at three wavenumbers satisfying k=k′+k″. In this triplet, nearly all of the energy from the instability goes to the damped mode. The very small fraction going to the zonal flow is balanced by small zonal flow damping. This combination of unstable mode, zonal flow, and stable mode minimizes the nonlinear frequency mismatch and avails itself of large coupling strengths associated with the zonal flow.
Exploring the importance of quantum effects in nucleation: The archetypical Nen case
Authors: Unn-Toc Wesley , Halberstadt Nadine , Meier Christoph , Mella Massimo
Published: July 2012

The effect of quantum mechanics (QM) on the details of the nucleation process is explored employing Ne clusters as test cases due to their semi-quantal nature. In particular, we investigate the impact of quantum mechanics on both condensation and dissociation rates in the framework of the microcanonical ensemble. Using both classical trajectories and two semi-quantal approaches (zero point averaged dynamics, ZPAD, and Gaussian-based time dependent Hartree, G-TDH) to model cluster and collision dynamics, we simulate the dissociation and monomer capture for Ne8 as a function of the cluster internal energy, impact parameter and collision speed. The results for the capture probability Ps(b) as a function of the impact parameter suggest that classical trajectories always underestimate capture probabilities with respect to ZPAD, albeit at most by 15%–20% in the cases we studied. They also do so in some important situations when using G-TDH. More interestingly, dissociation rates kdiss are grossly overestimated by classical mechanics, at least by one order of magnitude. We interpret both behaviours as mainly due to the reduced amount of kinetic energy available to a quantum cluster for a chosen total internal energy. We also find that the decrease in monomer dissociation energy due to zero point energy effects plays a key role in defining dissociation rates. In fact, semi-quantal and classical results for kdiss seem to follow a common “corresponding states” behaviour when the proper definition of internal and dissociation energies are used in a transition state model estimation of the evaporation rate constants.
Can density functional theory describe the NO(X2Π)-Ar and NO(A2Σ+)-Ar van der Waals complexes?
Authors: Ershova Olga V. , Besley Nicholas A.
Published: July 2012

The interaction of nitric oxide (NO) in its ground state X2Π and the first excited Rydberg state A2Σ+ with an argon (Ar) atom has been studied using density functional theory. A number of exchange-correlation functionals that account for dispersion interactions have been considered, including functionals with both empirical and non-empirical treatments of dispersion. To study NO in the excited state, the recently developed maximum overlap method was used. Potential energy surfaces for interaction of NO with Ar have been constructed and parameters describing their minima, such as NO-Ar distance, orientation angle, and binding energy, have been determined. A comparison with combined experimental and accurate theoretical data has been made in terms of these parameters and the overall shape of the surfaces. For the ground state, several of the functionals give very good results. Treatment of the excited state is more problematic. None of the functionals considered provides completely satisfactory results. Several reasons for this failure have been identified: an incorrect description of the non-dispersion component of the interaction and the damping of the dispersion interaction at small interatomic distances.
A comprehensive study of diffusion, thermodiffusion, and Soret coefficients of water-isopropanol mixtures
Authors: Mialdun A. , Yasnou V. , Shevtsova V. , Königer A. , Köhler W. , Alonso de Mezquia D. , Bou-Ali M. M.
Published: July 2012

We report on the measurement of diffusion (D), thermodiffusion (DT), and Soret (ST) coefficients in water-isopropanol mixtures by three different instrumental techniques: thermogravitational column in combination with sliding symmetric tubes, optical beam deflection, and optical digital interferometry. All the coefficients have been measured over the full concentration range. Results from different instruments are in excellent agreement over a broad overlapping composition (water mass fraction) range 0.2 < c < 0.7, providing new reliable benchmark data. Comparison with microgravity measurements (SODI/IVIDIL (Selected Optical Diagnostic Instrument/Influence of VIbration on DIffusion in Liquids)) onboard the International Space Station and with literature data (where available) generally gives a good agreement. Contrary to theoretical predictions and previous experimental expectations we have not observed a second sign change of ST at low water concentrations.
High resolution x-ray diffraction methodology for the structural analysis of one-dimensional nanostructures
Authors: Martínez-Tomás M. C. , Montenegro D. N. , Sallet V. , Muñoz-Sanjosé V.
Published: July 2012

We present a systematic high-resolution x-ray diffraction (HRXRD) methodology for the analysis of one-dimensional nanostructures, in order to give answer to some of the frequently found problems in the literature. Regarding the assessment of structural properties, it is well known that high resolution x-ray diffraction measurements can provide qualitative and quantitative information on several intrinsic parameters of the material. However when nanostructures are present, the difficulties in analyzing the diffracted signals coming from nanostructures and the homolayer on which they usually grow have led to a reduced use of this technique, one of the most powerful methods for structural analysis. The aim of this paper is to develop a methodology for the analysis of one-dimensional structures based on the mosaic model similar to the one used in the x-ray diffraction methods for layers and films. On this basis, it has been possible by making a careful and systematic application of HRXRD to obtain separated structural information of nanostructures and the layer/block/grain underneath. In addition, the existence of a long-range ordering of nanostructures has been studied from the detection and analysis of forbidden reflections. The HRXRD experimental work has been particularized on ZnO nanorods grown by catalyst-free metal organic chemical deposition on c-sapphire substrates.
Amyloid peptide Aβ40 inhibits aggregation of Aβ42: Evidence from molecular dynamics simulations
Authors: Viet Man Hoang , Li Mai Suan
Published: July 2012

Effects of amyloid beta (Aβ) peptide Aβ40 on secondary structures of Aβ42 are studied by all-atom simulations using the GROMOS96 43a1 force field with explicit water. It is shown that in the presence of Aβ40 the beta-content of monomer Aβ42 is reduced. Since the fibril-prone conformation N* of full-length Aβ peptides has the shape of beta strand-loop-beta strand this result suggests that Aβ40 decreases the probability of observing N* of Aβ42 in monomer state. Based on this and the hypothesis that the higher is the population of N* the higher fibril formation rates, one can expect that, in agreement with the recent experiment, Aβ40 inhibit fibril formation of Aβ42. It is shown that the presence of Aβ40 makes the salt bridge D23–K28 and fragment 18–33 of Aβ42 more flexible providing additional support for this experimental fact. Our estimation of the binding free energy by the molecular mechanics-Poisson-Boltzmann surface area method reveals the inhibition mechanism that Aβ40 binds to Aβ42 modifying its morphology.
Aqueous tert-butanol mixtures: A model for molecular-emulsions
Authors: Kežić Bernarda , Perera Aurélien
Published: July 2012

By analogy with micro-emulsion, we introduce the molecular-emulsion picture to describe particular aqueous mixtures. The analogy is set by introducing the equivalent of the Teubner-Strey structure factor, the latter which is traditionally used to describe the structure of micro-emulsions. The main difference resides in the fact that the size of the oil and water domains are not in the micrometer, but in the nanometer scale. This implies that the molecular size and the molecular geometry cannot be neglected anymore. The introduction of this analogy is used to settle the problem of properly describing with computer simulations highly micro-heterogeneous aqueous mixtures. In particular, the issue of whether or not the Kirkwood-Buff integrals represent solely concentration fluctuations is settled by showing the contribution of the micro-heterogeneity to these integrals through the presence of an associated pre-peak in the structure factors. Both the Optimized Potentials for Liquid State (OPLS) and Transferable Potential for Phase Equilibria–United Atoms (TraPPE-UA) force fields for tert-butanol turn out to be remarkably good in describing the structure of the corresponding aqueous mixtures, when the above-mentioned analogy with micro-emulsion is introduced to correct for the computational artifacts in the Kirkwood-Buff integrals.
A very sensitive ion collection device for plasma-laser characterization
Authors: Cavallaro S. , Torrisi L. , Cutroneo M. , Amato A. , Sarta F. , Wen L.
Published: July 2012

In this paper a very sensitive ion collection device, for diagnostic of laser ablated-target plasma, is described. It allows for reducing down to few microvolts the signal threshold at digital scope input. A standard ion collector is coupled to a transimpedance amplifier, specially designed, which increases data acquisition sensitivity by a gain ≈1100 and does not introduce any significant distortion of input signal. By time integration of current intensity, an amount of charge as small as 2.7 × 10−2 pC can be detected for photopeak events.