bluuebunny/crossref_metadata_2025 huggingface dataset:
Synoptic classification of lower troposphere profiles for dust days
Authors: Ganor E. , Stupp A. , Osetinsky I. , Alpert P.
Published: June 2010

The goal of this research is to identify meteorological characteristics distinguishing dust storm days from no‐dust days. During this pioneering research, the vertical profiles of temperature, wind components, and humidity for days with dust and with no dust were compared and analyzed in order to identify features accompanying dusty conditions. Three data sets, all for the 49 year period of 1958–2006, were used. The first was the daily dust observations at Tel Aviv, Israel. The second was the eastern Mediterranean daily surface synoptic classification. The third was the vertical data over the eastern Mediterranean grid point closest to Tel Aviv at 32.5°N, 35°E. The two latter data sets were based on the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis. The meteorological parameters were averaged over the 49 year period by season, pressure level, synoptic‐type, and dust and no‐dust days. Prominent differences between dust and no‐dust days were found for relative humidity and wind components during fall, winter, and spring at 700, 600, and 500 hPa levels. Relative humidity was found to be higher during dust episodes. This result, linking dust and humidity, looks promising for future research on connection between desert dust, ice nuclei, and precipitation. The governing eastern Mediterranean synoptic systems are low‐pressure systems. For these systems, vertical velocity (Omega) values are negative. It was found that absolute Omega values were higher on dust days than on days with no dust. Southerly and westerly components of wind were found to have higher values during dust days. It was found that for most synoptic systems, temperature below the 700 hPa level was equal or higher during dust days. Thus, during dust days the lower troposphere is unstable.
Influence of initial CMB temperature and other parameters on the thermal evolution of Earth's core resulting from thermochemical spherical mantle convection
Authors: Nakagawa Takashi , Tackley Paul J.
Published: June 2010

Here we present a wide‐ranging parameter study of the effects of initial core‐mantle boundary (CMB) temperature, concentration of radioactive potassium in the core, and density difference between harzburgite and mid‐ocean ridge basalt (MORB) in a coupled spherical model of thermochemical mantle convection and parameterized core heat balance. The initial CMB temperature is expected to be much higher than the solidus temperature of silicates at the base of the mantle. The results indicate that as with previous, purely thermal convection models, the final state of the system is only weakly dependent on initial CMB temperature unless the CMB becomes blanketed by a global layer of dense material. Fully 3‐D spherical cases have a very similar core evolution to cases in a 2‐D spherical annulus, giving confidence in the applicability of 2‐D spherical annulus geometry for modeling Earth's evolution. Obtaining a successful thermal evolution, in the sense of obtaining the correct present‐day inner core size and maintaining a geodynamo over geological time, is helped by the accumulation of piles of dense material at the CMB (subducted MORB in the present calculations) and a concentration of radiogenic K in the core in the range 400–800 ppm. The present‐day CMB heat flow is predicted to be around 9 TW. While this is lower than estimates based on calculating temperature gradients in regions where the postperovskite transition is seismically imaged, these tend to be areas of higher than average heat flux and thus likely overestimate the global heat flow.
Location for direct access to subglacial Lake Ellsworth: An assessment of geophysical data and modeling
Authors: Woodward J. , Smith A. M. , Ross N. , Thoma M. , Corr H. F. J. , King E. C. , King M. A. , Grosfeld K. , Tranter M. , Siegert M. J.
Published: June 2010

Subglacial Lake Ellsworth has been proposed as a candidate for direct measurement and sampling, to identify microbial life and extract sedimentary climate records. We present a detailed characterization of the physiography of this subglacial lake from geophysical surveys, allowing bathymetry and geomorphic setting to be established. Lake Ellsworth is 14.7 km × 3.1 km with an area of 28.9 km2. Lake depth increases downlake from 52 m to 156 m, with a water body volume of 1.37 km3. The ice thickness suggests an unusual thermodynamic characteristic, with the critical pressure boundary intersecting the lake. Numerical modeling of water circulation has allowed accretion of basal ice to be estimated. We collate this physiographic and modeling information to confirm that Lake Ellsworth is ideal for direct access and propose an optimal drill site. The likelihood of dissolved gas exchange between the lake and the borehole is also assessed.
First results from the Venetia Burney Student Dust Counter on the New Horizons mission
Authors: Poppe Andrew , James David , Jacobsmeyer Brian , Horányi Mihály
Published: June 2010

The Venetia Burney Student Dust Counter (SDC) onboard the New Horizons mission is an impact‐based dust detector designed to map the size and spatial variability of the interplanetary dust population throughout the solar system. SDC consists of fourteen permanently polarized polyvinylidene fluoride detectors that register a charge upon impact by hypervelocity dust grains. SDC can resolve the masses of grains with 10−12 < m < 10−9 g and measurements to date extend from 2.6 to 15.5 AU. SDC dust flux measurements taken inside the orbit of Jupiter are compared to previous measurements by the Ulysses and Galileo dust detectors to validate the instrument. Measurements taken outside Jupiter's orbit, spanning 6.8 AU to 15.5 AU, are also reported and compared with measurements by the Pioneer 10 and 11 meteoroid detectors and the Voyager 1 and 2 plasma wave instruments.
Role of Rossby wave breaking in the west Pacific teleconnection
Authors: Rivière G.
Published: June 2010

The dynamical link between the west Pacific (WP) teleconnection and Rossby wave breaking (RWB) events is analyzed during winter months using ERA40 reanalysis data from 1957 to 2002. The WP pattern which is characterized by latitudinal fluctuations of the Pacific jet is closely linked to variations in the nature of RWB, similarly to the North Atlantic Oscillation. More anticyclonic (cyclonic) RWBs than usual occur in the Central Pacific during the positive (negative) WP phase when the Pacific jet is more to the north (south) than usual. Time lag daily composites show that before the occurrence of an anticyclonic RWB event, WP anomalies close to the positive phase preexist that are then reinforced during the breaking leading to an increase of the WP index even few days after the peak of the event. Cyclonic RWB events have similar but opposite effects on the WP pattern since they trigger and maintain the negative phase. Finally, a comparison with the RWB anomalies of the Pacific‐North American (PNA) teleconnection is provided.
Is bigger better?
Authors: van Helden Paul
Published: June 2010

To close the gap between research and development, a number of funding organizations focus their efforts on large, translations research projects rather than small research teams and individual scientists. Yet, as Paul van Helden argues, if the support for small, investigator‐driven research decreases, there will soon be a dearth of novel discoveries for large research groups to explore.
The future of molecular evolution
Authors: Dean Antony M
Published: June 2010

Antony Dean explores the past, present and future of evolutionary theory and our continuing efforts to explain biological patterns in terms of molecular processes and mechanisms.
(Corrected) Osmotic stress and water isotope effects in kinesin-1 gliding motility assays
Authors: Koch Steven , Maloney Andy , Herskowitz Lawrence
Published: June 2010

The osmotic pressure and kinetic properties of water play important roles in biomolecular interactions. As pointed out by Parsegian, Rand, and Rau, these crucial roles are often overlooked[1]. In some fields, osmotic stress and isotope effects have been exploited for probing the role water plays in binding interactions of biomolecules. To our knowledge, there have been no studies of osmotic stress and water isotope effects for kinesin, and only a handful for myosin. We're currently using the gliding motility assay to see whether we can extract new information about kinesin-1 / microtubule interactions by changing osmotic stress and water isotopes. We will describe our open-source, automated analysis platform for extracting microtubule gliding speeds from image series. We will also show our preliminary analyses of the changes seen in gliding assays when done in heavy water (either heavy-hydrogen or heavy-oxygen) or osmolytes (betaine). We will discuss whether osmotic stress and isotopes, particularly heavy-oxygen water, might be an important tool for probing effects of water on binding interactions between kinesin and microtubules. We will also discuss potential applications of deuterium water for stabilizing microtubules and kinesin for lab or device applications.[1] Parsegian, V. A., Rand, R. P., & Rau, D. C. (1995). Macromolecules and water: probing with osmotic stress. Methods in Enzymology, 259.This work was supported by the DTRA CB Basic Research Program under Grant No. HDTRA1-09-1-008 in collaboration with Dr. Susan Atlas lab (UNM).CORRECTIONS: At the workshop, Erik Schaffer pointed out to us that some of our speed differences (casein data) were surely due to microscope increasing in temperature. I’ve edited the poster to correct for this. Thanks, Erik!
Grofit: Fitting biological growth curves
Authors: Kahm Matthias , Hasenbrink Guido , Lichtenberg-Frate Hella , Ludwig Jost , Kschischo Maik
Published: June 2010

Growth experiments are routinely used to analyze basic properties of a given organism or cellular model. Similarly, within the TRANSLUCENT project the characterization of cellular growth and particularly under conditions of high extra cellular potassium or sodium is an important task. Any growth analysis should ideally reveal a relationship between the concentration of a compound/substrate and its effect on a particular growth parameter. In view of the quite labor intensive analysis of hundreds of growth curves - sometimes not revealing ideal relationships - the Grofit-software was developed to support biologists and such approaches. Within the software package, specifically tailored regression and bootstrapping techniques are utilized to statistically estimate the effect of different growth conditions. Grofit was implemented in R, an open source statistical software environment. A complete description of the Grofit software and information about the implemented methods is given in a manuscript published by the Journal of Statistical Software. In addition the software is available from CRAN repositories or the developers homepage http://www.rheinahrcampus.de/Research-Group-of-Maik-Kschisc.2452.0.html
Evidence of mitochondrial dysfunction in fragile X-associated tremor/ataxia syndrome
Authors: Ross-Inta Catherine , Omanska-Klusek Alicja , Wong Sarah , Barrow Cedrick , Garcia-Arocena Dolores , Iwahashi Christine , Berry-Kravis Elizabeth , Hagerman Randi J. , Hagerman Paul J. , Giulivi Cecilia
Published: June 2010

FXTAS (fragile X-associated tremor/ataxia syndrome) is a late-onset neurodegenerative disorder that affects individuals who are carriers of premutation expansions (55–200 CGG repeats) in the 5′ untranslated region of the FMR1 (fragile X mental retardation 1) gene. The role of MD (mitochondrial dysfunction) in FXTAS was evaluated in fibroblasts and brain samples from premutation carriers with and without FXTAS symptoms, with a range of CGG repeats. This study resulted in several important conclusions: (i) decreased NAD- and FAD-linked oxygen uptake rates and uncoupling between electron transport and synthesis of ATP were observed in fibroblasts from premutation carriers; (ii) a lower expression of mitochondrial proteins preceded both in age and in CGG repeats the appearance of overt clinical involvement; (iii) the CGG repeat size required for altered mitochondrial protein expression was also smaller than that required to produce brain intranuclear inclusions from individuals with the premutation who died, suggesting that MD is an incipient pathological process occurring in individuals who do not display overt features of FXTAS; and (iv) on the basis of the CGG repeats, MD preceded the increase in oxidative/nitrative stress damage, indicating that the latter is a late event. MD in carriers of small CGG repeats, even when the allele size is not sufficient to produce FXTAS, may predispose them to other disorders (e.g. Parkinson's disease) that are likely to involve MD, and to environmental stressors, which may trigger the development of FXTAS symptoms. Detection of MD is of critical importance to the management of FXTAS, since it opens up additional treatment options for this disorder.
Wnt‐3 and Wnt‐3a play different region‐specific roles in neural crest development in avians
Authors: Dongkyun Kim , Jinsoo Song , Jin Eun‐Jung
Published: June 2010

Wnt signalling regulates cell proliferation and cell fate determination during embryogenesis. However, little is known about the developmental role of one Wnt family member, Wnt‐3, during avian development. To investigate the possible functions of Wnt‐3, its expression pattern was determined using whole‐mount in situ hybridization. Wnt‐3 is expressed in important signalling centres, including the dorsal neural tube, Hensen's node and the AER (apical ectodermal ridge). Most interestingly, Wnt‐3 is expressed in the dorsal neural tube as a gradient, with the strongest expression anterior in the trunk. Furthermore, this study showed that Wnt‐3 and Wnt‐3a play a different role in neural crest lineages derived from different axial level of neural tube. Wnt‐3 might be involved in proliferation of neural crest lineages, whereas Wnt‐3a plays an important role in melanogenesis in vagal. However, both Wnt‐3 and Wnt‐3a cause a significant increase in melanogenesis in the trunk neural crest lineage.
Cleft Lip Repair: Technical Refinements for the Wide Cleft
Authors: Meyer Eric , Seyfer Alan
Published: June 2010

Clefts of the lip and palate are among the most common congenital malformations. A unilateral deformity is the most common type of cleft, but even within this subgroup there is a great deal of variety due to the accompanying severe distortion of the upper lip, cheek, nose, and maxilla. To repair such a variety of clefts with good aesthetic results, several general incisional approaches should be mastered along with a variety of subtle techniques that improve the end product. The most common repair utilized in America is the Millard rotation-advancement technique. This is partly due to the perceived superiority in results compared with other repairs and the ease with which this repair can be taught to residents. This repair places the scar along an artificial philtral column and is often quite sufficient in small clefts. Unfortunately, adoption of this “one size fits all” approach can limit the arsenal of the surgeon facing the vast array of differing cleft lip deformities. For example, the modified triangular flap, or Tennison-Randall repair, can be of value when presented with the wider unilateral cleft lip. In an effort to not only demonstrate that excellent results can be achieved when incisional patterns (Millard and Tennison) are used appropriately (small versus large clefts), we compared the results of two types of repairs, performed by a single surgeon over a period of 30 years. In addition, a variety of subtle techniques are reviewed to assist in obtaining excellent aesthetic results for any size repair.
Treatment of Pseudoaneurysm of Internal Maxillary Artery: A Case Report
Authors: Barbalho Jimmy Charles Melo , Santos Eliardo Silveira , Menezes José Maria Sampaio , Gonçalves Fabricio Rocha , Chagas Otacilio Luiz
Published: June 2010

Pseudoaneurysms are rare lesions secondary to blunt or penetrating trauma, temporomandibular joint surgery, or orthognathic surgery. Nonsurgical interventions are the treatment of choice for pseudoaneurysms. In the case reported here, endovascular injection of acrylic glue was successful in the treatment of a pseudoaneurysm of the internal maxillary artery secondary to fracture of the zygomatic bone.
Bifocal Distraction to Regenerate Segmental Mandibular Defects Using a Custom Made Device: A Report of Two Cases
Authors: Krishnan Sriram , Subramaniam Ramkumar
Published: June 2010

Background and objective: Mandibular reconstruction following tumor ablative surgery had been a challenge. It has gone through days of temporary stabilization with k-wire, stainless steel reconstruction plate to avascularized and vascularized bone grafts with varying degree of success and failure. Reconstruction with vascularized bone grafts, though most definitive, requires special expertise, expensive equipment, and long operative time. It also produces donor site morbidity and requires a significant learning curve. With the development of transport distraction techniques there has been a paradigm shift from “reconstructive” to “regenerative” surgery. The objective of this study was to identify the feasibility of an internal device for reconstruction of extensive mandibular defects. Methods and material: This article is to highlight a process of attempted mandibular regeneration in two cases using an indigenously designed distractor device. In individuals with extensive post ablative mandibular defects who were unwilling to have a secondary surgical site or were medically unfit for a long reconstructive procedure, the distraction technique can be used to reconstruct the lost mandibular structures. Conclusion: A satisfactory amount of regenerate was achieved using a bifocal distraction osteogenesis technique for extensive defects of the mandible. The custom made device which was used for this purpose was moderately satisfactory and requires further evaluation and refinement.
Management of Temporal Bone Trauma
Authors: Patel Alpen , Groppo Eli
Published: June 2010

The temporal bones are paired structures located on the lateral aspects of the skull and contribute to the skull base. Trauma is usually the result of blunt head injury and can result in damage to the brain and meninges, the middle and internal ear, and the facial nerve. Complications can include intracranial hemorrhage, cerebral contusion, CSF leak and meningitis, hearing loss, vertigo, and facial paralysis. To prevent these complications, diagnosis followed by appropriate medical and surgical management is critical. Diagnosis relies primarily on physical signs and symptoms as well as radiographic imaging. Emergent intervention is required in situations involving herniation of the brain into the middle ear cavity or hemorrhage of the intratemporal carotid artery. Patients with declining facial nerve function are candidates for early surgical intervention. Conductive hearing loss can be corrected surgically as an elective procedure, while sensorineural hearing loss carries a poor prognosis, regardless of management approach. Children generally recover from temporal bone trauma with fewer complications than adults and experience a markedly lower incidence of facial nerve paralysis.
Experiments in DIII-D toward achieving rapid shutdown with runaway electron suppression
Authors: Hollmann E. M. , Commaux N. , Eidietis N. W. , Evans T. E. , Humphreys D. A. , James A. N. , Jernigan T. C. , Parks P. B. , Strait E. J. , Wesley J. C. , Yu J. H. , Austin M. E. , Baylor L. R. , Brooks N. H. , Izzo V. A. , Jackson G. L. , van Zeeland M. A. , Wu W.
Published: June 2010

Experiments have been performed in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] toward understanding runaway electron formation and amplification during rapid discharge shutdown, as well as toward achieving complete collisional suppression of these runaway electrons via massive delivery of impurities. Runaway acceleration and amplification appear to be well explained using the zero-dimensional (0D) current quench toroidal electric field. 0D or even one-dimensional modeling using a Dreicer seed term, however, appears to be too small to explain the initial runaway seed formation. Up to 15% of the line-average electron density required for complete runaway suppression has been achieved in the middle of the current quench using optimized massive gas injection with multiple small gas valves firing simultaneously. The novel rapid shutdown techniques of massive shattered pellet injection and shell pellet injection have been demonstrated for the first time. Experiments using external magnetic perturbations to deconfine runaways have shown promising preliminary results.
Strength and elastic moduli of TiN from radial x-ray diffraction under nonhydrostatic compression up to 45 GPa
Authors: Chen Haihua , Peng Fang , Mao Ho-kwang , Shen Guoyin , Liermann Hanns-Peter , Li Zuo , Shu Jinfu
Published: June 2010

The high pressure behavior of titanium nitride (TiN) was investigated using synchrotron radial x-ray diffraction (RXRD) under nonhydrostatic compression up to 45.4 GPa in a diamond-anvil cell. We obtained the hydrostatic compression equation of state of TiN. Fitting to the third-order Birch–Murnaghan equation of state, the bulk modulus derived from nonhydrostatic compression data varies from 232 to 353 GPa, depending on angle ψ, the orientation of the diffraction planes with respect to the loading axis. The RXRD data obtained at ψ=54.7° yield a bulk modulus K0=282±9 GPa with pressure derivative K0′ fixed at 4. We have analyzed the deformation mechanisms by analyzing the (111), (200), (220), (311), and (222) peaks in the x-ray diffraction under pressures. The ratio of uniaxial stress component to shear modulus t/G ranges from 0.007–0.027 at the pressure of 6.4–45.4 GPa. It was found that the TiN sample could support a maximum uniaxial stress component t of 8.6 GPa, when it started to yield at 45.4 GPa under uniaxial compression. And the aggregate elastic moduli of TiN at high pressure were determined from the synchrotron RXRD measurements.
Vibrational properties of (Gd1−xYx)3Ga5O12 solid solutions
Authors: Papagelis K. , Arvanitidis J. , Vinga E. , Christofilos D. , Kourouklis G. A. , Kimura H. , Ves S.
Published: June 2010

The vibrational properties of the (Gd1−xYx)3Ga5O12 (0≤x≤1) mixed garnet crystals are investigated at normal conditions by Raman and reflectivity infrared (IR)-spectroscopy while the end members of the series have been theoretically investigated by means of a rigid ion model. The IR experimental spectra were analyzed by means of the Kramers–Kronig relations and the Lorentz oscillator model. The obtained results are compared and discussed in detail with the theory, providing useful parameters for estimating and understanding the IR optical properties of mixed garnets. The majority of the expected Raman peaks is resolved and their symmetry assignment has been elucidated. The clear one mode behavior of the observed Raman and IR modes as a function of x confirms the formation of solid solutions, resulting from the replacement of the cations at the dodecahedral lattice sites. A softening of almost all Raman and IR modes is found as the unit cell volume increases (x decreases). Finally, the small dispersion of the Grüneisen parameters γi (ω) indicates that the binding forces are of the same nature and order of magnitude and that the binding strength between the various molecular units is quite comparable.
Terahertz radiation from a magnetoplasma wave excited by ultrashort optical pulses
Authors: Sumikura Hisashi , Nagashima Takeshi , Hangyo Masanori , Tani Masahiko
Published: June 2010

We have studied terahertz (THz) emission from InAs excited by femtosecond optical pulses in magnetic fields. The time-domain measurements of the THz radiation from n-InAs show that the polarity of the THz waveform is reversed at B∼±5 T, where the minimum of the radiation intensity is observed. We have analyzed the emission characteristics including the excitation and the propagation of a magnetoplasma wave. As a result, we have concluded that the transverse electric field component of the magnetoplasma wave is emitted into the air as THz radiation at high magnetic fields (|B|>5 T). In contrast, at low magnetic fields (|B|<5 T) the THz emission is dominated by the dipole radiation from the transient surface polarization that is driven by the longitudinal electric field component of the magnetoplasma wave. The crossover between these contributions to the THz emission results in the power minima and the polarity reversals of the THz radiation.
Driven magnetic reconnection near the Dreicer limit
Authors: Roytershteyn V. , Daughton W. , Dorfman S. , Ren Y. , Ji H. , Yamada M. , Karimabadi H. , Yin L. , Albright B. J. , Bowers K. J.
Published: June 2010

The influence of Coulomb collisions on the dynamics of driven magnetic reconnection in geometry mimicking the Magnetic Reconnection eXperiment (MRX) [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)] is investigated using two-dimensional (2D) fully kinetic simulations with a Monte Carlo treatment of the collision operator. For values of collisionality typical of MRX, the reconnection mechanism is shown to be a combination of collisionless effects, represented by off-diagonal terms in the electron stress tensor, and collisional momentum exchange between electrons and ions. The ratio of the reconnection electric field ER to the critical runaway field Ecrit provides a convenient measure of the relative importance of these two mechanisms. The structure of electron-scale reconnection layers in the presence of collisions is investigated in light of the previously reported [S. Dorfman et al., Phys. Plasmas 15, 102107 (2008)] discrepancy in the width of the electron reconnection layers between collisionless simulations and experimental observations. It is demonstrated that the width of the layer increases in the presence of collisions, but does not substantially deviate from its collisionless values, given by the electron crossing orbit width, unless ER⪡Ecrit. Comparison with MRX observations demonstrates that the layer width in 2D simulations with Coulomb collisions is substantially smaller than the value observed in the low-density experiments with ER≲Ecrit, indicating that physical mechanisms beyond those included in the simulations control the structure of the electron layers in these experiments.
Orientation-dependent phase switching process and strains of Pb0.97La0.02(Zr0.85Sn0.13Ti0.02)O3 antiferroelectric thin films
Authors: Hao Xihong , Zhai Jiwei , Shang Fei , Zhou Jing , An Shengli
Published: June 2010

Highly (100) and (111)-oriented Pb0.97La0.02(Zr0.85Sn0.13Ti0.02)O3 antiferroelectric (AFE) thin films were fabricated through a sol-gel processing. The effects of orientation on phase transformation behaviors and strains of the AFE thin films were studied systemically. As compared to (100)-preferred AFE thin films, the (111)-oriented films showed a smaller forward phase switching field of 250 kV/cm and higher stains of 0.79%. It is therefore concluded that AFE thin films with (111)-preferred orientation are more suitable to be used as microactuators.
Direct conversion of light-polarization information into electric voltage using photoinduced inverse spin-Hall effect in Pt/GaAs hybrid structure: Spin photodetector
Authors: Ando K. , Morikawa M. , Trypiniotis T. , Fujikawa Y. , Barnes C. H. W. , Saitoh E.
Published: June 2010

The direct conversion of light-polarization information into electric voltage has been demonstrated using the photoinduced inverse spin-Hall effect in a Pt/GaAs hybrid structure. In the GaAs layer, spin-polarized carriers are generated by the illumination of circularly polarized light, which induces a pure-spin current in the Pt layer through the interface. The pure-spin current is converted into an electromotive force using the inverse spin-Hall effect (ISHE) in the Pt layer. The electromotive force due to the photoinduced ISHE was found to be proportional to the degree of circular polarization of the illuminated light outside the sample in spite of the presence of the Pt top layer, which is consistent with a calculation based on the analysis for light propagation in multilayer structures. This conversion of light-polarization information into electric voltage works at room temperature without bias voltage and magnetic fields, and thus can be used as a spin photodetector.
Efficient micromixing of a highly viscous biosample with water using orbital shaking and microchannels
Authors: Yuan Liang , Zheng Yuan F. , Chen Weidong
Published: June 2010

Micromixing of a highly viscous biosample with water using orbital shaking and microchannels is considered. Existing methods mix biosamples by only shaking microwells or by specially designed microstirrers which are ineffective or inapplicable for highly viscous materials, let alone small volumes at microliter or nanoliter levels. Our method mixes a viscous biosample with water in microwells using orbital shaking plus an innovative block which divides the microwells into two compartments and is built in with microchannels. The mixing method with the block in the microwell is efficient compared to mixing in the microwell without the block. In this paper, the design of the block is presented, the model of the flow of the biosamples in the microchannel is developed, the Reynolds number of the flow in the microchannel is calculated, and the dynamics of the mixing process is analyzed. Furthermore, a miniature wireless video sensor system is used to observe the mixing process which verifies the model of the flow in the analysis. Finally, x-ray diffraction experiments on mixing monoolein with water are presented. In each trial, x-ray diffraction is used to evaluate the results of mixing which confirms that the proposed approach is effective for mixing a highly viscous biosample with water.
On the computation of fundamental measure theory in pores with cylindrical symmetry
Authors: Mariani Néstor J. , Mocciaro Clarisa , Campesi María A. , Barreto Guillermo F.
Published: June 2010

Classical density functional theories usually separate the formulation of the excess Helmholtz free energy in hard-body and energetic contributions. Fundamental measure theories (FMTs) have emerged as the preferred choice to account for the former contribution. The evaluation of geometrically weighted densities (convolutions) arisen in FMT for hard spheres in long cylindrical cavities is addressed in this paper. Previously, Malijevský [J. Chem. Phys. 126, 134710 (2007)] reported expressions containing elliptic integrals for the kernels of the convolutions involving scalar and vectorial weights. Here, the set of kernels is extended to second and third order tensorial weights that introduce desirable dimensional crossover properties to the evaluation of the excess free energy. An alternative formulation for the convolutions, which greatly facilitates their computation, is also proposed. Integrals of the original kernels arise in this way and a set of expressions for them, again expressed in terms of elliptic integrals, is presented here. With the aim of providing a computationally simple framework to evaluate equilibrium density profile with cylindrical symmetry, a procedure based on direct minimization of the discretized grand potential energy, rather than employing the Euler–Lagrange equilibrium conditions, is discussed and used to identify differences between two FMT formulations, including or not second order tensorial kernels in very narrow cylindrical pores.
Analysis of dual-mode thin film bulk acoustic resonators based on polar c-axis tilted wurtzite gallium nitride
Authors: Qin Lifeng , Wang Qing-Ming
Published: June 2010

We present the analytical study of dual-mode thin film bulk acoustic resonators (FBARs) based on wurtzite gallium nitride (GaN) thin films with tilted c-axis orientation. The normal-plane and in-plane electric polarization vector components caused by the titled c-axis orientation induce the coexistence of the thickness longitudinal and thickness shear modes in the thin film resonator. Due to the c-axis orientation dependency of material properties including elastic stiffness, dielectric constants, and piezoelectric coefficients, bulk wave properties of FBARs including acoustic velocity and electromechanical coupling coefficient, and electrical impedance spectra are greatly affected by the tilt angle. It is found that the pure longitudinal mode occurs at θ=0° and 66.4°, and the pure shear mode occurs at θ=42.8° and 90°. In addition, the electromechanical coupling coefficient for thickness shear mode has a maximum value 3.18% at θ=34.2°, which is larger than the maximum value for pure thickness longitudinal mode 2.44% at θ=0°. The calculation results show that FBARs based on tilted c-axis wurtzite GaN thin films are promising for frequency control device design and applications.
A new calibration code for the JET polarimeter
Authors: Gelfusa M. , Murari A. , Gaudio P. , Boboc A. , Brombin M. , Orsitto F. P. , Giovannozzi E. ,   JET EFDA Contributors
Published: June 2010

An equivalent model of JET polarimeter is presented, which overcomes the drawbacks of previous versions of the fitting procedures used to provide calibrated results. First of all the signal processing electronics has been simulated, to confirm that it is still working within the original specifications. Then the effective optical path of both the vertical and lateral chords has been implemented to produce the calibration curves. The principle approach to the model has allowed obtaining a unique procedure which can be applied to any manual calibration and remains constant until the following one. The optical model of the chords is then applied to derive the plasma measurements. The results are in good agreement with the estimates of the most advanced full wave propagation code available and have been benchmarked with other diagnostics. The devised procedure has proved to work properly also for the most recent campaigns and high current experiments.
Electron attachment to sulfur oxyhalides: SOF2, SOCl2, SO2F2, SO2Cl2, and SO2FCl attachment rate coefficients, 300–900 K
Authors: Miller Thomas M. , Friedman Jeffrey F. , Caples Connor M. , Shuman Nicholas S. , Van Doren Jane M. , Bardaro Michael F. , Nguyen Pho , Zweiben Cindy , Campbell Matthew J. , Viggiano A. A.
Published: June 2010

Electron attachment to SOF2, SOCl2, SO2F2, SO2FCl, and SO2Cl2 was studied with two flowing-afterglow Langmuir-probe apparatuses over the temperature range 300–900 K. Attachment rate coefficients at 300 K are ka=2.6±0.8×10−10(SOF2), 1.8±0.5×10−8(SOCl2), 4.8±0.7×10−10(SO2F2), 2.4±0.7×10−9(SO2Cl2), and 2.0±0.6×10−7 cm3 s−1(SO2FCl). Arrhenius plots of the data imply activation energies of 56±22 meV(SOF2), 92±40(SO2F2), 44±22 meV(SOCl2), and 29±15 meV(SO2Cl2). The rate coefficients for SO2FCl decrease slightly with temperature, commensurate with the decrease in the capture rate coefficient. Electron attachment to SOF2 and SO2F2 is nondissociative, while reaction with SOCl2, SO2FCl, and SO2Cl2 is dissociative. Dissociative attachment is dominated by channels arising from S–Cl bond cleavage but also includes a minor channel forming a dihalide product ion. Branching fraction data are reported for the dissociative attachment channels.
Upconversion luminescence in Er3+ doped and Er3+/Yb3+ codoped zirconia and hafnia nanocrystals excited at 980 nm
Authors: Gómez Luis A. , Menezes Leonardo de S. , de Araújo Cid B. , Gonçalves Rogeria R. , Ribeiro Sidney J. L. , Messaddeq Younes
Published: June 2010

Frequency upconversion (UC) luminescence in nanocrystalline zirconia (ZrO2) and hafnia (HfO2) doped with Er3+ and Yb3+ was studied under continuous-wave excitation at 980 nm. Samples of ZrO2:Er3+, ZrO2:Er3+/Yb3+, and HfO2:Er3+/Yb3+ were prepared by the sol-gel technique and characterized using x-ray diffraction and electron microscopy. A study of the infrared-to-green and infrared-to-red UC processes was performed including the analysis of the spectral and the temporal behavior. The mechanisms contributing to the UC luminescence were identified as excited state absorption and energy transfer among rare-earth ions.
Transportable high-energy high-power generator
Authors: Novac B. M. , Smith I. R. , Senior P. , Parker M. , Louverdis G.
Published: June 2010

High-power applications sometimes require a transportable, simple, and robust gigawatt pulsed power generator, and an analysis of various possible approaches shows that one based on a twin exploding wire array is extremely advantageous. A generator based on this technology and used with a high-energy capacitor bank has recently been developed at Loughborough University. An H-configuration circuit is used, with one pair of diagonally opposite arms each comprising a high-voltage ballast inductor and the other pair exploding wire arrays capable of generating voltages up to 300 kV. The two center points of the H configuration provide the output to the load, which is coupled through a high-voltage self-breakdown spark gap, with the entire autonomous source being housed in a metallic container. Experimentally, a load resistance of a few tens of Ohms is provided with an impulse of more than 300 kV, having a rise time of about 140 ns and a peak power of over 1.7 GW. Details of the experimental arrangement and typical results are presented and diagnostic measurements of the current and voltage output are shown to compare well with theoretical predictions based on detailed numerical modeling. Finally, the next stage toward developing a more powerful and energetic transportable source is outlined.
Persistent template effect in InAs/GaAs quantum dot bilayers
Authors: Clarke E. , Howe P. , Taylor M. , Spencer P. , Harbord E. , Murray R. , Kadkhodazadeh S. , McComb D. W. , Stevens B. J. , Hogg R. A.
Published: June 2010

The dependence of the optical properties of InAs/GaAs quantum dot (QD) bilayers on seed layer growth temperature and second layer InAs coverage is investigated. As the seed layer growth temperature is increased, a low density of large QDs is obtained. This results in a concomitant increase in dot size in the second layer, which extends their emission wavelength, reaching a saturation value of around 1400 nm at room temperature for GaAs-capped bilayers. Capping the second dot layer with InGaAs results in a further extension of the emission wavelength, to 1515 nm at room temperature with a narrow linewidth of 22 meV. Addition of more InAs to high density bilayers does not result in a significant extension of emission wavelength as most additional material migrates to coalesced InAs islands but, in contrast to single layers, a substantial population of regular QDs remains.
Natural constructal emergence of vascular design with turbulent flow
Authors: Cetkin E. , Lorente S. , Bejan A.
Published: June 2010

Here, we show that vascular design emerges naturally when a volume is bathed by a single stream in turbulent flow. The stream enters the volume, spreads itself to bathe the volume, and then reconstitutes itself as a single stream before it exits the volume. We show that in the pursuit of a smaller global flow resistance and larger volumes, the flow architecture changes stepwise from a stack of identical elements bathed in parallel flow (like a deck of cards) to progressively more complex structures configured as trees matched canopy to canopy. The transition from one architecture to the next occurs at a precise volume size, which is identified. Each transition marks a decrease in the rate at which the global flow resistance increases with the volume size. This decrease accelerates as the volume size increases. The emergence of such vasculatures for turbulent flow is compared with the corresponding phenomenon when the flow is laminar. To predict this design generation phenomenon is essential to being able to scale up the designs of complex flow structures, from small scale models to life size models. The constructal law is a bridge between the principles of physics and biology.
Oxygen-vacancy-related high-temperature dielectric relaxation in SrTiO3 ceramics
Authors: Wang Xiaofei , Lu Xiaomei , Zhang Chao , Wu Xiaobo , Cai Wei , Peng Song , Bo Huifeng , Kan Yi , Huang Fengzhen , Zhu Jinsong
Published: June 2010

Quantum paraelectric SrTiO3 has resulted in many investigations because of the anomalous properties. Here, using the conventional solid-state reaction method, we fabricated polycrystalline SrTiO3 ceramics with pure cubic perovskite structure. A dielectric loss peak is observed at around 450 K and 100 Hz and it shifts to higher temperature with increasing frequency. The typical high-temperature dielectric relaxation process is confirmed to be related to the oxygen vacancies (OVs) inside ceramics. More interestingly, a Cole–Cole fitting to loss peaks reveals a weaker correlation among OVs for such dielectric materials compared with that of ferroelectrics.
Complex micelles from the self-assembly of amphiphilic triblock copolymers in selective solvents
Authors: He Pengtao , Li Xuejin , Kou Dazhi , Deng Mingge , Liang Haojun
Published: June 2010

The self-assembled microstructures of amphiphilic block copolymers depend on the selectivity of solvents for each block. By changing the selectivity of solvents, defined in terms of the repulsive interactions between the solvent and the hydrophilic/hydrophobic particles, an extensive simulation study on the spontaneous formation of complex micelles from amphiphilic triblock copolymers in a dilute solution is presented. The dynamic pathways in the formation of these assemblies have been investigated using a particle-based dissipative particle dynamics approach. In addition, the potential mechanism behind the formation of these microstructures has also been studied, which may be helpful in explaining how these aggregates are formed and in understanding the general principle of amphiphilic molecules.
Effect of hydrostatic pressure on magnetic phase transition and magnetocaloric properties of (Sm0.8Nd0.2)0.52Sr0.48MnO3
Authors: Arumugam S. , Sarkar P. , Mandal P. , Murugeswari A. , Matsubayashi K. , Ganguli C. , Uwatoko Y.
Published: June 2010

We have investigated the effect of hydrostatic pressure (P) on ferromagnetic (FM) phase transition and magnetocaloric properties of (Sm0.8Nd0.2)0.52Sr0.48MnO3 single crystal. At ambient pressure, the system undergoes a first order FM transition associated with large magnetic entropy change (ΔSM). The temperature distribution of ΔSM exhibits an asymmetric behavior with respect to TC. The application of pressure increases magnetization, shifts the FM transition to higher temperature, and weakens the metamagnetism. As a result, |ΔSM| decreases and its thermal distribution becomes more symmetric as compared to P=0.
Energy upconversion in holmium doped lead–germano–tellurite glass
Authors: Kamma Indumathi , Reddy B. Rami
Published: June 2010

Holmium doped lead–germano–tellurite glass was prepared by the melt quenching technique. The Judd–Ofelt intensity parameters were estimated as Ω2=7.6×10−20, Ω4=12.9×10−20, and Ω6=2.5×10−20 cm2. Radiative transition probabilities and lifetimes were also determined for some of the levels. Room temperature upconversion emissions have been observed from Ho3+ at 497 nm under 532 nm laser excitation, and at 557 and 668 nm under 762 nm laser excitation. The upconversion emission mechanisms were found to be due to a step wise excitation process. Upconversion emission intensity enhanced in a heat treated glass.
Cholesky decomposition-based definition of atomic subsystems in electronic structure calculations
Authors: Sánchez de Merás Alfredo M. J. , Koch Henrik , Cuesta Inmaculada García , Boman Linus
Published: June 2010

Decomposing the Hartree–Fock one-electron density matrix and a virtual pseudodensity matrix, we obtain an orthogonal set of normalized molecular orbitals with local character to be used in post-Hartree–Fock calculations. The applicability of the procedure is illustrated by calculating CCSD(T) energies and CCSD molecular properties in reduced active spaces.
Electro-osmotic flows over highly polarizable dielectric surfaces
Authors: Yariv Ehud , Davis Anthony M. J.
Published: June 2010

A thin-Debye-layer macroscale model is developed and analyzed for electrokinetic flows about dielectric surfaces, wherein solid polarization modifies the zeta-potential distribution. The harmonic electric potential within the solid is governed by a nonlinear boundary condition, which constitutes a generalization of the linear Robin-type condition of Yossifon et al. [Phys. Fluids 19, 068105 (2007)] to voltages comparable with the thermal scale. The resulting polarization model is demonstrated in the classical context of spherical-particle electrophoresis, where the electrophoretic mobility—now a function of applied-field magnitude and solid permittivity—is evaluated using both eigenfunction series expansions and asymptotic approximations. For strong polarization, the mobility saturates at a field-dependent value which is lower than the comparable Smoluchowski slope. At strongly applied fields, the mobility diminishes at a rate that corresponds to a logarithmic increase of particle velocity with applied-field magnitude.
Convergent flow in a two-layer system and mountain building
Authors: Perazzo Carlos Alberto , Gratton Julio
Published: June 2010

With the purpose of modeling the process of mountain building, we investigate the evolution of the ridge produced by the convergent motion of a system consisting of two layers of liquids that differ in density and viscosity to simulate the crust and the upper mantle that form a lithospheric plate. We assume that the motion is driven by basal traction. Assuming isostasy, we derive a nonlinear differential equation for the evolution of the thickness of the crust. We solve this equation numerically to obtain the profile of the range. We find an approximate self-similar solution that describes reasonably well the process and predicts simple scaling laws for the height and width of the range as well as the shape of the transversal profile. We compare the theoretical results with the profiles of real mountain belts and find an excellent agreement.
Neutral dissociation of the I, I′, and I″ vibronic progressions of O2
Authors: Demekhin Ph. V. , Sukhorukov V. L. , Schmoranzer H. , Ehresmann A.
Published: June 2010

It is suggested that the main mechanism for neutral dissociation of the I, I′, and I″ vibronic progressions in O2 is due to their interaction with the vibrational continuum of the 1πu−1(A Π2u)3sσg Π3u(vε) Rydberg state (J state) leading to the formation of the O(2p4 P3)+O∗(2p3(S4)3s S3) fragments. In order to justify this, the O I 2p3(S4)3s S3→2p4 P3 fluorescence emission cross section following the neutral dissociation of the O2 1πu−1(a Π4u)4sσg/3dδg/3dσg Π3u(v) Rydberg states is simulated in the exciting-photon energy range of 14.636–16.105 eV. The results of high-resolution measurements (H. Liebel et al., J. Phys. B 34, 2581 (2001)) can be reproduced if a small adjustment of the computed potential curve of the J state is applied. Non-Franck–Condon resonant intensity distributions of the I, I′, and I″ progressions observed in the experiment are qualitatively explained by the presence of the O2 1πg−1(X Π2g)npσu/nfσu/nfδu Π3u perturber states. Present calculations allow to decide between two different assignments of the I, I′, and I″ states available in literature.
Spin-orbit interaction effects on magnetoresistance in graphene-based ferromagnetic double junctions
Authors: Bai Chunxu , Wang Juntao , Jia Shuanwen , Yang Yanling
Published: June 2010

Based on the transfer-matrix method, the spin polarized transport properties through a ballistic graphene-based quantum tunneling junctions with the spin-orbit interaction have been investigated. It is found that the magnetoresistance (MR) oscillates with the Rashba spin-orbit interaction (RSOI) and the intrinsic spin-orbit interaction (ISOI). In addition, when the RSOI is present, the negative MR can be observed due to the spin-flip effect, whereas for the ISOI alone no such negative MR can be found. It is anticipated to apply such a phenomenon to design the electron devices based on the graphene.