bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of an increase in the incidence of odontogenic sinusitis over the last decade in the UK
Authors: Hoskison E , Daniel M , Rowson J E , Jones N S
Published: September 2011

Background:

Dental disease is a recognised cause of sinusitis. We perceived an increased incidence of sinusitis secondary to dental disease in recent years. This study reviews the incidence of odontogenic sinusitis, its clinical features and treatment.

Methods:

Medical records of patients with odontogenic sinusitis were identified using the senior author's clinical database and Hospital Information Support System data (January 2004 to December 2009).

Results:

Twenty-six patients were identified, nine females and 17 males (age range, 17–73 years). Rhinorrhoea and cacosmia were the commonest symptoms (81 and 73 per cent, respectively), with presence of pus the commonest examination finding (73 per cent). Causative dental pathology included periapical infection (73 per cent), oroantral fistula (23 per cent) and a retained root (4 per cent). In all 26 cases, treatment resulted in complete resolution of symptoms; 21 (81 per cent) required sinus surgery. The number of patients with odontogenic sinusitis undergoing surgery has steadily increased, from no cases in 2004 to 10 in 2009 (accounting for 8 per cent of all patients requiring sinus surgery). Reduced access to dental care may be responsible.

Conclusion:

The incidence of odontogenic sinusitis appears to be increasing. The importance of assessing the oral cavity and dentition in patients with rhinosinusitis is therefore emphasised.
‘Phases and stages, circles and cycles’: Willie Nelson and the concept album
Authors: Stimeling Travis D.
Published: September 2011

While many rock artists explored the compositional possibilities of the concept album in the 1960s and 1970s, Nashville's country music community largely ignored the format. But a few artists working on the fringes of country music – and who, notably, aligned themselves with the countercultural images and attitudes of the time – did begin to experiment with the format in the first years of the 1970s. Chief among them was country songwriter and recording artist Willie Nelson who, by the dawn of the 1970s, was on the verge of breaking away from Music Row to seek more lucrative opportunities in Texas. This article explores the role that Nelson's experimentation with the concept album played in his efforts to adopt a countercultural image, develop a younger audience and challenge the hegemony of the country music industry. Moreover, close examination of Nelson's compositional approach to three albums –Yesterday's Wine(1971),Phases and Stages(1974) andRed Headed Stranger(1975) – reveals that Nelson consciously blended the singles-based approach to songwriting that predominated in 1960s and 1970s Nashville and the extended narrative and musical forms of contemporaneous rock music to create musical products that suited the needs of country radio and rock fans alike.
THE CONSEQUENCES OF TAXATION
Authors: Slemrod Joel
Published: September 2011

The consequences of taxation matter for the optimal design of the tax
system. Those consequences depend on behavioral responses to taxation, as
summarized by the elasticity of taxable income. Although this elasticity
depends on characteristics of preferences, such as the elasticity of
substitution between goods and leisure, it also depends on the avoidance
technology, and on the response of government to avoidance behavior. It
depends on the size of states, and the amount of tax coordination and
harmonization. To some degree the elasticity of response can be affected
by government policies, and the government need not accept it passively,
but rather should put in place policies that optimally determine it.
Reference values for echocardiographic measurements of healthy newborns
Authors: Güzeltaş Alper , Eroğlu Ayşe Güler
Published: September 2011

Objective

To assess the reference values of M-mode echocardiographic measurements in healthy newborns according to body weight.

Methods

From January, 2008 to June, 2008, a total of 250 – 130 female and 120 male – term healthy newborns were included in the study. M-mode echocardiographic measurements were recorded by a paediatric cardiologist in accordance with the American Society of Echocardiography recommendations. Right ventricular anterior wall end-diastolic thickness, right ventricular end-diastolic diameter, interventricular septum end-diastolic thickness, left ventricular end-diastolic diameter, left ventricular posterior wall end-diastolic thickness, interventricular septum end-systolic thickness, left ventricular end-systolic diameter, left ventricular posterior wall end-systolic thickness, aortic root dimension, left atrium dimension, left ventricular ejection, and shortening fraction were measured.

Results

The values of echocardiographic measurements revealed a good correlation with body weight. When body weight increased, the measured values also increased in parallel. The measured values were not influenced by gender. Ejection and shortening fraction parameters did not change with body weight and gender.

Conclusion

In this study, normative values related to body weight for cardiac chambers and wall thickness were determined in healthy newborns. These reference values can be used to evaluate whether newborns have normal or abnormal echocardiographic measurement.
Three-dimensional transoesophageal echocardiography to evaluate surgical removal of subaortic membrane
Authors: Séguéla Pierre-Emmanuel , Alacoque Xavier , Acar Philippe
Published: September 2011

Transoesophageal echocardiography is a useful tool for the intra-operative assessment of surgical repair in children with congenital cardiac malformations. We report the case of a subaortic membrane removal in a nine-year-old boy. Three-dimensional transoesophageal echocardiography revealed a mitral perforation created during the procedure.
Evaluating and predicting lifetime in capacitive MEMS switches
Authors: Goldsmith Charles L. , O'Brien Sean , Molinero David , Hwang James C. M.
Published: September 2011

An empirical model has been proposed which provides an excellent fit to the drift of pull-in and release voltages of a MEMS capacitive switch due to bulk dielectric charging. This model correctly fits the linear time dependence over short time spans and transitions to a logarithmic dependence over longer time spans. Using this model to fit measured data enables a quick and efficient determination of the rate of dielectric charging, as well as providing a worst-case prediction of when the switch will fail due to dielectric charging. This model has been used to explore the impact of applied voltage, temperature, and duty factor on switch lifetime.
Recent and Upcoming Events for Prospective Memory Researchers
Authors: Smith Rebekah E.
Published: September 2011

This section contains short contributions involving the following aspects of prospective memory research: Recent and upcoming symposia on prospective memory (including a symposium in honor of Richard Marsh to be held at the 5th International Conference on Memory, York, UK, August 2011) / Special journal issues on prospective memory (2000-2011) / Fourth International Conference on Prospective Memory (Naples, Italy, 2013) / The Prospective Memory Group (web discussion group)
Dynamics of North Atlantic Deep Water masses during the Holocene
Authors: Hoogakker Babette A. A. , Chapman Mark R. , McCave I. Nick , Hillaire‐Marcel Claude , Ellison Christopher R. W. , Hall Ian R. , Telford Richard J.
Published: September 2011

High resolution flow speed reconstructions of two core sites located on Gardar Drift in the northeast Atlantic Basin and Orphan Knoll in the northwest Atlantic Basin reveal a long‐term decrease in flow speed of Northeast Atlantic Deep Water (NEADW) after 6,500 years. Benthic foraminiferal oxygen isotopes of sites currently bathed in NEADW show a 0.2‰ depletion after 6,500 years, shortly after the start of the development of a carbon isotope gradient between NEADW and Norwegian Sea Deep Water. We consider these changes in near‐bottom flow vigor and benthic foraminiferal isotope records to mark a significant reorganization of the Holocene deep ocean circulation, and attribute the changes to a weakening of NEADW flow during the mid to late Holocene that allowed the shoaling of Lower Deep Water and deeper eastward advection of Labrador Sea Water into the northeast Atlantic Basin.
A simulation analysis of the advective effect on evaporation using a two‐phase heat and mass flow model
Authors: Zeng Yijian , Su Zhongbo , Wan Li , Wen Jun
Published: September 2011

The concept of enhanced vapor transfer in unsaturated soils has been questioned for its reliance on soil temperature gradient, which leads to consideration of other mechanisms of vapor transfer, e.g., advective vapor transfer due to soil air pressure gradient. Although the advective flux is an important portion of evaporation, there is a lack of knowledge of its effect on evaporation. In order to assess the dependence of evaporation on the soil air pressure gradient, a vertical one‐dimensional two‐phase heat and mass flow model is developed that fully considers diffusion, advection, and dispersion. The proposed model is calibrated with field measurements of soil moisture content and temperature in the Badain Jaran Desert. The proposed model is then used to investigate the advective effect in both low‐ and high‐permeability soils. The advective effect is reflected by underestimating evaporation when the airflow is neglected and is more evident in the low‐permeability soil. Neglecting airflow causes an underestimation error of 53.3% on the day right after a rainfall event in the low‐permeability soil (7.9 × 10−4 cm s−1) and 33.3% in the high‐permeability soil (2 × 10−3 cm s−1). The comparisons of driving forces and conductivities show that the isothermal liquid flux, driven by the soil matric potential gradient, is the main reason for the underestimation error.
Altered Postnatal Development of Cortico—Hippocampal Neuronal Electric Activity in Mice Deficient for the Mitochondrial Aspartate—Glutamate Transporter
Authors: Gómez-Galán Marta , Makarova Julia , Llorente-Folch Irene , Saheki Takeyori , Pardo Beatriz , Satrústegui Jorgina , Herreras Oscar
Published: September 2011

The deficiency in the mitochondrial aspartate/glutamate transporter Aralar/AGC1 results in a loss of the malate-aspartate NADH shuttle in the brain neurons, hypomyelination, and additional defects in the brain metabolism. We studied the development of cortico/hippocampal local field potential (LFP) in Aralar/AGC1 knockout (KO) mice. Laminar profiles of LFP, evoked potentials, and unit activity were recorded under anesthesia in young (P15 to P22) Aralar-KO and control mice as well as control adults. While LFP power increased 3 to 7 times in both cortex and hippocampus of control animals during P15 to P22, the Aralar-KO specimens hardly progressed. The divergence was more pronounced in the CA3/hilus region. In parallel, spontaneous multiunit activity declined severely in KO mice. Postnatal growth of hippocampal-evoked potentials was delayed in KO mice, and indicated abnormal synaptic and spike electrogenesis and reduced output at P20 to P22. The lack of LFP development in KO mice was accompanied by the gradual appearance of epileptic activity in the CA3/hilus region that evolved to status epilepticus. Strikingly, CA3 bursts were poorly conducted to the CA1 field. We conclude that disturbed substrate supply to neuronal mitochondria impairs development of cortico—hippocampal LFPs. Aberrant neuronal electrogenesis and reduced neuron output may explain circuit dysfunction and phenotype deficiencies.
Weight, Length, and Growth in Cutbow Trout (Oncorhynchus mykiss x clarkii)
Authors: Parker David , Avers Thomas , Courtney Michael
Published: September 2011

Background:

The cutbow trout (Oncorhynchus mykiss x clarkii) is a fertile hybrid of rainbow and cutthroat trout. Little published length-weight data is available for this hybrid, and a standard weight curve is not established. Eleven Mile Reservoir is a clear mountain reservior in Colorado with a surface area of 13.4 square kilometers, an average depth of 10 m, and a maximum depth of 41 m. 80,000 cutbow trout were stocked through the ice in late winter before samples were taken.

Materials and Methods:

Angling provided 171 samples which were weighed and measured (total length and fork length). Dressed weight was also determined with the scales, head, and entrails removed. Estimates of parameters a and b in the model, W(L) = aLb, were obtained by both linear least-squares (LLS) regression (log(W) = log(a) + b log(L)) and non-linear least-squares (NLLS) regression, where W is weight in kg and L is length in cm. Parameter estimates of an improved model, W(L) = (L/L1)b, were also determined by NLLS regression; the parameter L1 is the typical length of a fish weighing 1 kg. The resulting best-fit parameters, parameter standard errors, and covariances are compared between the two models. Average weight and length are considered for each month from June through October to estimate growth rates for fish stocked over the winter. Standard weights (relative to the rainbow trout and cutthroat trout standard weight curves) are also determined, along with the ratio of total length to fork length and typical dressed weight percentage.

Results:

The improved model parameter estimates were b = 2.662 and L1 = 45.32 cm, with correlation coefficient r = 0.969. From June to October, mean relative weight decreased from 101.5% to 93.6% relative to the rainbow trout standard weight and 114.5% to 103.2% relative to the cutthroat trout standard weight as mean total lengths increased from 34.4 cm to 41.9 cm and the mean weights increased from 0.505 kg to 0.830 kg. Typical dressed weight is 71% of the total weight.Conclusion: Eleven mile reservoir is an excellent trout fishery, capable of producing large numbers of cutbow trout in good condition. The cutbow trout is well suited to this kind of mountain reservoir and grows fast. As might be expected, the weights of cutbow trout of a given length tend to fall between the standard weights of the rainbow and the cutthroat. For the season, the average relative weight was 97.0% relative to the rainbow trout, and 108.3% relative to cutthroat trout.
Comment on "Embryological evidence identifies wing digits in birds as digits 1, 2, and 3."
Authors: Xu Xing , Choiniere Jonah , Sullivan Corwin , Han Fenglu
Published: September 2011

Tamura et al. (Science, 11 Febuary 2011, p. 753) claim that the three avian wing digits should be identified as digits I-III based on new embryological data and suggest that these identifications help to remove the conflict between the paleontological data and developmental data concerning the homology of the avian digits. However, their results are not novel, and the authors fail to address the critical problems relating to this interesting issue.
SBGN-ED – working with the Systems Biology Graphical Notation
Authors: Czauderna Tobias , Schreiber Falk
Published: September 2011

The Systems Biology Graphical Notation - SBGN [1] provides a standard for the visual representation of biochemical and cellular processes. SBGN aims to improve information exchange and to support the collaborative creation of large maps based on individual modules. The language contains three views of biological processes covering different levels of detail:(1) Process Description (PD): this sublanguage provides a detailed presentation of the temporal dependencies of biological interactions in a network;(2) Entity Relationship (ER): this sublanguage displays the relationships in which a given entity can participate in a network; and(3) Activity Flow (AF): this sublanguage shows the flow of information between biological entities in an abstract way.SBGN aims to support a more efficient and accurate communication of biological knowledge between different research communities. However, to increase its usage, tools for editing, validating, layouting and translating SBGN maps are desirable.We present novel developments in SBGN-ED [2], a tool which allows the creation of all three types of SBGN maps from scratch or the editing of existing maps, the validation of these maps for syntactical and semantical correctness, the translation of networks from databases such as KEGG into SBGN and the export of SBGN maps into several file and image formats. SBGN-ED is based on the Vanted system [3] for the integration, analysis and visualisation of experimental data within biological networks and functional hierarchies. We furthermore present some applications based on SBGN-ED such as RIMAS [4].SBGN-ED is freely available from http://www.sbgn-ed.org. The web site contains also tutorials and example files.[1] N. Le Novère et al. (2009) The systems biology graphical notation. Nature Biotechnology, 27: 735–741.[2] B.H. Junker, C. Klukas and F. Schreiber (2006) VANTED: a system for advanced data analysis and visualization in the context of biological networks. BMC Bioinformatics, 7: 109.1–109.13.[3] T. Czauderna, C. Klukas and F. Schreiber (2010) Editing, validating, and translating of SBGN maps. Bioinformatics, 26(18): 2340-2341.[3] A. Junker, A. Hartmann, F. Schreiber, H. Bäumlein (2010) An engineers view on regulation of seed development. Trends in Plant Science 15(6): 303-307.
The magnetic-distortion probe: Velocimetry in conducting fluids
Authors: Miralles Sophie , Verhille Gautier , Plihon Nicolas , Pinton Jean-François
Published: September 2011

A new type of velocimeter, capable of local velocity measurements in conducting fluids, is introduced. The principle of the “magnetic-distortion probe” is based on the measurement of the induced magnetic field by the flow of a conducting fluid in the vicinity of a localized magnetic field. The new velocimeter has no moving parts, and can be enclosed in a sealed cap, easing the implementation in harsh environments, such as liquid metals. The proposed method allows one to probe both the continuous part and fluctuations of the velocity, the temporal and spatial resolution being linked to the actual geometric configuration of the probe. A prototype probe has been tested in a gallinstan pipe flow and in a fully turbulent flow of liquid gallium generated by the counter rotation of two coaxial impellers in a cylinder. The signals have been compared to a reference potential probe and show very good agreement both for time-averaged velocities and turbulent fluctuations. The prototype is shown to detect motion from a few cm s−1 to a few m s−1. Moreover, the use of the magnetic-distortion probe with large-scale applied magnetic field is discussed.
Effect of the microstructure closed pore content on the acoustic behavior of polyurethane foams
Authors: Doutres Olivier , Atalla Noureddine , Dong Kevin
Published: September 2011

The present paper proposes to investigate the links between the microstructure of polyurethane foams and their sound absorbing efficiency, and more specifically the effect of membranes closing the cells. This study is based on the complete characterization of 15 polyurethane foam with various cell sizes and reticulation rates (i.e., open pore content): (i) characterization of the microstructure properties (cell size Cs, strut thickness t, reticulation rate Rw…) from SEM pictures, (ii) characterization of nonacoustic parameters (porosity Φ, airflow resistivity σ, tortuosity α∞…) from direct and indirect methods. Existing analytical links between microstructure properties and nonacoustic parameters are first applied to fully reticulated materials. Then, they are improved empirically to account for the presence of the closed pore content. The proposed expressions associated to the Johnson-Champoux-Allard porous model allow a good estimation of the sound absorbing behavior of all polyurethane foams, fully reticulated or not. This paper also demonstrates the important effect of the presence of cell membranes: increase of the airflow resistivity, tortuosity, and the ratio between the thermal and viscous characteristic lengths while decreasing these two characteristic lengths. Thus, the sound absorption efficiency at low frequencies is improved but can be worsened in some higher frequency bands.
Computer simulation of electron thermalization in CsI and CsI(Tl)
Authors: Wang Zhiguo , Xie YuLong , Cannon Bret D. , Campbell Luke W. , Gao Fei , Kerisit Sebastien
Published: September 2011

A Monte Carlo (MC) model was developed and implemented to simulate the thermalization of electrons in inorganic scintillator materials. The model incorporates electron scattering with both longitudinal optical and acoustic phonons. In this paper, the MC model was applied to simulate electron thermalization in CsI, both pure and doped with a range of thallium concentrations. The inclusion of internal electric fields was shown to increase the fraction of recombined electron-hole pairs and to broaden the thermalization distance and thermalization time distributions. The MC simulations indicate that electron thermalization, following γ-ray excitation, takes place within approximately 10 ps in CsI and that electrons can travel distances up to several hundreds of nanometers. Electron thermalization was studied for a range of incident γ-ray energies using electron-hole pair spatial distributions generated by the MC code NWEGRIM (NorthWest Electron and Gamma Ray Interaction in Matter). These simulations revealed that the partition of thermalized electrons between different species (e.g., recombined with self-trapped holes or trapped at thallium sites) vary with the incident energy. Implications for the phenomenon of nonlinearity in scintillator light yield are discussed.
Resistive switching characteristics and mechanism of thermally grown WOx thin films
Authors: Biju Kuyyadi P. , Liu Xinjun , Siddik Manzar , Kim Seonghyun , Shin Jungho , Kim Insung , Ignatiev Alex , Hwang Hyunsang
Published: September 2011

Resistive switching characteristics of thermally oxidized tungsten thin films and their switching mechanism were investigated, modifying thickness of the active layer (WOx) by varying oxidation conditions. Two types of switching were observed in Pt/WOx/W memory devices. Thinner film (t ≤ 15 nm) exhibits clockwise switching (CWS) with filamentary characteristics, whereas thicker film (t ≥ 25 nm) exhibits counter-clockwise switching (CCWS) with more homogeneous conduction. Both switching modes are highly reliable and show good cycling endurance. The conduction phenomena in two different switching modes were examined. In the case of CWS, the conduction mechanism changes from Schottky emission to ohmic conduction due to the local bypass of Schottky barrier formed at Pt/WOx interface by oxygen vacancies. Contrary to CWS, CCWS showed a completely different conduction mechanism. The high resistance state is dominated by the Schottky emission at low electric field and by Poole–Frenkel emission at high electric field, whereas the low resistance state exhibits the Schottky emission. Different types of switching behavior might be attributed to the non-homogenous defect distribution across the active layer. A possible conduction sketch for two types switching behaviors is also discussed.
Nonadiabatic quantum dynamics of C(1D)+H2→CH+H: Coupled-channel calculations including Renner-Teller and Coriolis terms
Authors: Defazio Paolo , Bussery-Honvault Béatrice , Honvault Pascal , Petrongolo Carlo
Published: September 2011

The Renner-Teller (RT) coupled-channel dynamics for the ${\rm C}( {{}^1D} )+{\rm H}_{\rm 2} ( {X{}^{\rm 1}{\rm \Sigma }_g^ + } ) \to {\rm CH}( {X^2 \Pi } )\break + {\rm H}( {{}^2S} )$C(D1)+H2(XΣg+1)→ CH (X2Π)+H(S2) reaction has been investigated for the first time, considering the first two singlet states $\tilde a{}^1A^{\rm \prime }$ã1A′ and $\tilde b{}^1A^{\prime \prime }$b̃1A′′ of CH2 dissociating into the products and RT couplings, evaluated through the ab initio matrix elements of the electronic angular momentum. We have obtained initial-state-resolved probabilities, cross sections and thermal rate constants via the real wavepacket method for both coupled electronic states. In contrast to the ${\rm N}( {{}^2D} ) + {\rm H}_{\rm 2} ( {X{}^{\rm 1}{\rm \Sigma }_g^ + } )$N(D2)+H2(XΣg+1) system, RT effects tend to reduce probabilities, cross sections, and rate constants in the low energy range compared to Born-Oppenheimer (BO) ones, due to the presence of a repulsive RT barrier in the effective potentials and to long-lived resonances. Furthermore, contrary to BO results, the rate constants have a positive temperature dependence in the 100–400 K range. The two-state RT rate constant at 300 K, lower than the BO one, remains inside the error bars of the experimental value.
Magnetic properties of single 3d transition metals adsorbed on graphene and benzene: A density functional theory study
Authors: Sargolzaei Mahdi , Gudarzi Farideh
Published: September 2011

We have demonstrated magnetic properties of single 3d transition metal (TM) atom (from Sc to Ni) adsorbed on the surface of graphene and benzene in the framework of relativistic density functional theory. Binding energies, spin and orbital magnetic moments, and magnetic anisotropy energies (MAE) of the TM-graphene and TM-benzene structures were determined. Our calculations show that magnetic moments of most 3d TM atoms added to the surface of graphene and benzene are partially quenched when compared to their free atomic state. We found very robust orbital moments for Co adatom on graphene and benzene and Cr adatom on benzene compared to the almost quenched orbital moments for the other 3d TM adatoms. It is also found that Co-graphene and Co-benzene show very large magnetic anisotropy energies, with easy axis perpendicular to the graphene plane and aligned to the C6 rotation axis of the benzene molecule, whereas the other 3d TM adatoms behave like a soft magnet.
Distribution-function approach to free energy computation
Authors: Sakuraba Shun , Matubayasi Nobuyuki
Published: September 2011

Connections are explored between the free energy difference of two systems and the microscopic distribution functions of the energy difference. On the basis of a rigorous relationship between the energy distribution functions and the free energy, the scheme of error minimization is introduced to derive accurate and simple methods of free energy computation. A set of distribution-function approaches are then examined against model systems, and the newly derived methods exhibit state-of-art performance. It is shown that the notion of error minimization is powerful to improve the free energy calculation using distribution functions.
Dynamic in situ chromosome immobilisation and DNA extraction using localized poly(N-isopropylacrylamide) phase transition
Authors: Eriksen Johan , Thilsted Anil Haraksingh , Marie Rodolphe , Lüscher Christopher James , Nielsen Lars Bue , Svendsen Winnie Edith , Szabo Peter , Kristensen Anders
Published: September 2011

A method of in situ chromosome immobilisation and DNA extraction in a microfluidic polymer chip was presented. Light-induced local heating was used to induce poly(N-isopropylacrylamide) phase transition in order to create a hydrogel and embed a single chromosome such that it was immobilised. This was achieved with the use of a near-infrared laser focused on an absorption layer integrated in the polymer chip in close proximity to the microchannel. It was possible to proceed to DNA extraction while holding on the chromosome at an arbitrary location by introducing protease K into the microchannel.
Thermoreversible gelation of isotactic-rich poly(N-isopropylacrylamide) in water
Authors: Nakano Shinya , Ogiso Takao , Kita Rio , Shinyashiki Naoki , Yagihara Shin , Yoneyama Masaru , Katsumoto Yukiteru
Published: September 2011

We report the experimentally determined phase diagram for an aqueous solution of isotactic-rich poly(N-isopropylacrylamide) (PNiPAM) composed of the sol-gel transition curve and the cloud-point curve. The meso diad content of isotactic-rich PNiPAM is 64%, and it is soluble in water at low temperatures, but undergoes a sol-to-gel transition with increasing temperature in the investigated concentration range of 1.8 wt. %–6.0 wt. %. With a further increase in temperature, the system becomes turbid. The gel formation and clouding behavior are thermally reversible. This is the first observation of thermoreversible gelation under the cloud-point temperature for an aqueous solution of PNiPAM. On the basis of the determined phase diagram, we carried out light scattering experiments to characterize the sol-gel transition behavior as a function of temperature.
First-principles calculations of 17O nuclear magnetic resonance chemical shielding in Pb(Zr1/2Ti1/2)O3 and Pb(Mg1/3Nb2/3)O3: Linear dependence on transition-metal/oxygen bond lengths
Authors: Pechkis Daniel L. , Walter Eric J. , Krakauer Henry
Published: September 2011

First-principles density functional theory oxygen chemical shift tensors were calculated for A(B,B′)O3 perovskite alloys Pb(Zr1/2Ti1/2)O3 (PZT) and Pb(Mg1/3Nb2/3)O3 (PMN). Quantum chemistry methods for embedded clusters and the gauge including projector augmented waves (GIPAW) method [C. J. Pickard and F. Mauri, Phys. Rev. B 63, 245101 (2001)]10.1103/PhysRevB.63.245101 for periodic boundary conditions were used. Results from both methods are in good agreement for PZT and prototypical perovskites. PMN results were obtained using only GIPAW. Both isotropic δiso and axial δax chemical shifts were found to vary approximately linearly as a function of the nearest-distance transition-metal/oxygen bond length, rs. Using these results, we argue against Ti clustering in PZT, as conjectured from recent 17O NMR magic-angle-spinning measurements. Our findings indicate that 17O NMR measurements, coupled with first-principles calculations, can be an important probe of local structure in complex perovskite solid solutions.
Infrared spectroscopy of endohedral HD and D2 in C60
Authors: Ge Min , Nagel U. , Hüvonen D. , Rõõm T. , Mamone S. , Levitt M. H. , Carravetta M. , Murata Y. , Komatsu K. , Lei Xuegong , Turro N. J.
Published: September 2011

We report on the dynamics of two hydrogen isotopomers, D2 and HD, trapped in the molecular cages of a fullerene C60 molecule. We measured the infrared spectra and analyzed them using a spherical potential for a vibrating rotor. The potential, vibration-rotation Hamiltonian, and dipole moment parameters are compared with previously studied H2@C60 parameters [M. Ge, U. Nagel, D. Hüvonen, T. Rõõm, S. Mamone, M. H. Levitt, M. Carravetta, Y. Murata, K. Komatsu, J. Y.-C. Chen, and N. J. Turro, J. Chem. Phys. 134, 054507 (2011)10.1063/1.3535598]. The isotropic part of the potential is similar for all three isotopomers. In HD@C60, we observe mixing of the rotational states and an interference effect of the dipole moment terms due to the displacement of the HD rotation center from the fullerene cage center.
Tuning the thermal relaxation of transition-metal ferrite nanoparticles through their intrinsic magnetocrystalline anisotropy
Authors: Vargas José M. , Srivastava Abhishek , Yourdkhani Amin , Zaldivar Luis , Caruntu Gabriel , Spinu Leonard
Published: September 2011

Monodispersed ferrite nanoparticles of Fe3O4, MnFe2O4, and CoFe2O4 (near to 10 nm), were synthesized by organometallic synthesis, showing the same homogeneous chemical, morphological, and crystalline characteristics. The study and correlation of the thermal relaxation processes were analyzed through static and dynamic measurements. Due to the intrinsic chemical characteristics and magnetocrystalline anisotropy of the ferrite nanoparticles, the energy barrier can be tuned to a range between 1100 K ≤ EB ≤ 7300 K, showing an alternative approach for tuning the magnetic dynamic properties, in contrast to the well-known mechanism through particle-size-effects. Specific loss power efficiencies were evaluated for the three ferrite samples. Comparing the three samples at the maximum ac frequency of ν = 10 kHz, MnFe2O4 exhibits the single-peak maximum of loss with the value of 273 erg/s · g at T = 65 K, whereas for the CoFe2O4, a maximum of 132 erg/s · g (T = 217 K) was determined. A considerable drop in the efficiency was determined for the Fe3O4 nanoparticles, with the value of 20 erg/s · g at T = 43.5 K.
Scaling laws for thermal conductivity of crystalline nanoporous silicon based on molecular dynamics simulations
Authors: Fang Jin , Pilon Laurent
Published: September 2011

This study establishes that the effective thermal conductivity keff of crystalline nanoporous silicon is strongly affected not only by the porosity fν and the system’s length Lz but also by the pore interfacial area concentration Ai. The thermal conductivity of crystalline nanoporous silicon was predicted using non-equilibrium molecular dynamics simulations. The Stillinger-Weber potential for silicon was used to simulate the interatomic interactions. Spherical pores organized in a simple cubic lattice were introduced in a crystalline silicon matrix by removing atoms within selected regions of the simulation cell. Effects of the (i) system length ranging from 13 to 130 nm, (ii) pore diameter varying between 1.74 and 5.86 nm, and (iii) porosity ranging from 8% to 38%, on thermal conductivity were investigated. A physics-based model was also developed by combining kinetic theory and the coherent potential approximation. The effective thermal conductivity was proportional to (1 − 1.5fν) and inversely proportional to the sum (Ai/4 + 1/Lz). This model was in excellent agreement with the thermal conductivity of nanoporous silicon predicted by molecular dynamics simulations for spherical pores (present study) as well as for cylindrical pores and vacancy defects reported in the literature. These results will be useful in designing nanostructured materials with desired thermal conductivity by tuning their morphology.
Sharp constants in the Sobolev embedding theorem and a derivation of the Brezis-Gallouet interpolation inequality
Authors: Bartuccelli Michele V. , Gibbon John D.
Published: September 2011

Sharp estimates are obtained for the constants appearing in the Sobolev embedding theorem on the two-dimensional torus. Furthermore, a version of the Brezis-Gallouet interpolation inequality is obtained with an explicit but not necessarily optimal constant in the leading term, namely, the logarithmic term. The constants are expressed in terms of the Riemann zeta-function and the Dirichlet beta-series.
Synthesis and magnetic reversal of bi-conical Ni nanostructures
Authors: Biziere N. , Lassalle Ballier R. , Clochard M. C. , Viret M. , Wade T. L. , Balanzat E. , Wegrowe J. E.
Published: September 2011

Template synthesis in polyethylene terephthalate (PET) membranes has been used to grow hour glass shaped nickel nanowires with a constriction in the range of tens of nanometers at the center. Anisotropic magnetoresistance measurements have been performed on a single nanowire to follow magnetization reversal of the structure. The results are explained via 3D micromagnetic simulations showing the appearance of a complex vortex state close to the constriction whose propagation depends on the angle between the cone axis and the applied field. The interest of this original growth process for spintronics is discussed.
Electrical conduction processes in ZnO in a wide temperature range 20–500 K
Authors: Lien Chien-Chi , Wu Chih-Yuan , Li Zhi-Qing , Lin Juhn-Jong
Published: September 2011

We have investigated the electrical conduction processes in as-grown and thermally cycled ZnO single crystal as well as as-grown ZnO polycrystalline films over the wide temperature range 20–500 K. In the case of ZnO single crystal between 110 and 500 K, two types of thermal activation conduction processes are observed. This is explained in terms of the existence of both shallow donors and intermediately deep donors that are consecutively excited to the conduction band as the temperature increases. By measuring the resistivity ρ(T) of a given single crystal after repeated thermal cycling in vacuum, we demonstrate that oxygen vacancies play an important role in governing the shallow donor concentrations but leave the activation energy (≈ 27±2 meV) largely intact. In the case of polycrystalline films, two types of thermal activation conduction processes are also observed between ~150 and 500 K. Below ~150 K, we found an additional conductionprocess due to the nearest-neighbor-hopping conduction mechanism, which takes place in the shallow impurity band. As the temperature further decreases below ~80 K, a crossover to the Mott variable-range-hopping conduction process is observed. Taken together with our previous measurements on ρ(T) of ZnO polycrystalline films in the temperature range 2–100 K [Y. L. Huang et al., J. Appl. Phys. 107, 063715 (2010)], this work establishes a quite complete picture of the overall electrical conduction mechanisms in the ZnO material from liquid-helium temperatures up to 500 K.
Monte-Carlo simulation of ternary blends of block copolymers and homopolymers
Authors: Pike Darin Q. , Müller Marcus , de Pablo Juan J.
Published: September 2011

We perform a theoretically informed coarse grain Monte-Carlo simulation in the nPT-ensemble and the Gibbs ensemble on symmetric ternary mixtures of AB-diblock copolymers with the corresponding homopolymers. We study the lamellar period by varying the length and amount of homopolymers. The homopolymer distribution within the lamellar morphology is determined as is the maximum amount of homopolymer within the lamellae. Gibbs ensemble simulations are used to locate the three-phase coexistence between two homopolymer-rich phases and a lamellar phase.
Terahertz propagation properties of free-standing woven-steel-mesh metamaterials: Pass-bands and signatures of abnormal group velocities
Authors: Sabah Cumali , Thomson Mark D. , Meng Fanzhen , Tzanova Slava , Roskos Hartmut G.
Published: September 2011

We explore steel-mesh structures, which are commercially available as insets of chemical particle filters, in terms of their metamaterial properties below 1 THz, including both single- and multi-layer structures. Their pass-band characteristics are very similar to those reported for hole arrays in metal films, exhibiting power transmission as high as 88% for the lowest transmission band of single-layer structures. The transmission minima are explained in terms of the Rayleigh-Wood anomaly. The phase properties of the transmitted THz pulses reveal negative group delays of several picoseconds, i.e., abnormal group velocities, in spectral regions between pass-bands.
Enhanced microwave magnetic and attenuation properties for Z-type barium ferrite composites with flaky fillers
Authors: Li Z. W. , Yang Z. H. , Kong L. B.
Published: September 2011

Microwave attenuation characteristics and magnetic and dielectric properties have been studied for Ba3CoxZn2-xFe24O41 with x = 0.8 and 2.0 ferrite flaky-filler composites. Results show that μ0′ and μmax″ are enhanced by >150 and >70%, respectively, and ɛ′ and ɛ″ are almost the same, as compared to conventional composites. Therefore, the percentage bandwidth WP is expanded from 110% to 150% for reflectivity RL ≤−10 dB for the flaky-filler composites, which achieves 75% of the theoretically maximum bandwidth. For all composites, two matching frequencies are found. The first matching frequency is attributed to the quarter-wavelength resonator and the second matching frequency is mainly determined by the values of both μ′ and ɛ′. At the second matching thickness, the flaky-filler composites also exhibit good attenuation characteristics with low reflectivity of RL <−20 dB and WP= 40% at L band.
Growth of a Richtmyer-Meshkov turbulent layer after reshock
Authors: Thornber B. , Drikakis D. , Youngs D. L. , Williams R. J. R.
Published: September 2011

This paper presents a numerical study of a reshocked turbulent mixing layer using high-order accurate Implicit Large-Eddy-Simulations (ILES). Existing theoretical approaches are discussed, and the theory of Youngs (detailed in Ref. 1) is extended to predict the behaviour of a reshocked mixing layer formed initially from a shock interacting with a broadband instability. The theory of Mikaelian2 is also extended to account for molecular mixing in the single-shocked layer prior to reshock. Simulations are conducted for broadband and narrowband initial perturbations and results for the growth rate of the reshocked layer and the decay rate of turbulent kinetic energy show excellent agreement with the extended theoretical approach. Reshock causes a marginal decrease in mixing parameters for the narrowband layer, but a significant increase for the broadband initial perturbation. The layer properties are observed to be very similar post-reshock, however, the growth rate exponent for the mixing layer width is higher in the broadband case, indicating that the reshocked layer still has a dependence (although weakened) on the initial conditions. These results have important implications for Unsteady Reynolds Averaged Navier Stokes modelling of such instabilities.
Mechanical exfoliation of graphene for the passive mode-locking of fiber lasers
Authors: Martinez Amos , Fuse Kazuyuki , Yamashita Shinji
Published: September 2011

Graphene exhibits wavelength-independent, saturable optical absorption with fast response time, and large modulation depth. Thus, it is an attractive material for the saturable absorption of fiber lasers. In this paper, we report a simple method for the in-situ monitoring of the deposition of few-layers graphene in an optical fiber end by mechanical exfoliation. Saturable absorbers with different number of graphene layers (from 4 layers of graphene to few 10 s of layers) are prepared and low threshold, self-starting passive mode-locked operation of a fiber laser with sub-picosecond pulse duration is demonstrated.
Carbon tips as electrodes for single-molecule junctions
Authors: Castellanos-Gomez Andres , Bilan Stefan , Zotti Linda A. , Arroyo Carlos R. , Agraït Nicolás , Carlos Cuevas Juan , Rubio-Bollinger Gabino
Published: September 2011

We study electron transport through single-molecule junctions formed by an octanethiol molecule bonded with the thiol anchoring group to a gold electrode and the opposing methyl endgroup to a carbon tip. Using the scanning tunneling microscope based break junction technique, we measure the electrical conductance of such molecular junctions. We observe the presence of well-defined conductance plateaus during the stretching of the molecular bridge, which is the signature of the formation of a molecular junction.
Effects of climate change on fish reproduction and early life history stages
Authors: Pankhurst Ned W. , Munday Philip L.
Published: September 2011

Seasonal change in temperature has a profound effect on reproduction in fish. Increasing temperatures cue reproductive development in spring-spawning species, and falling temperatures stimulate reproduction in autumn-spawners. Elevated temperatures truncate spring spawning, and delay autumn spawning. Temperature increases will affect reproduction, but the nature of these effects will depend on the period and amplitude of the increase and range from phase-shifting of spawning to complete inhibition of reproduction. This latter effect will be most marked in species that are constrained in their capacity to shift geographic range. Studies from a range of taxa, habitats and temperature ranges all show inhibitory effects of elevated temperature albeit about different environmental set points. The effects are generated through the endocrine system, particularly through the inhibition of ovarian oestrogen production. Larval fishes are usually more sensitive than adults to environmental fluctuations, and might be especially vulnerable to climate change. In addition to direct effects on embryonic duration and egg survival, temperature also influences size at hatching, developmental rate, pelagic larval duration and survival. A companion effect of marine climate change is ocean acidification, which may pose a significant threat through its capacity to alter larval behaviour and impair sensory capabilities. This in turn impacts on population replenishment and connectivity patterns of marine fishes.
Detecting range shifts among Australian fishes in response to climate change
Authors: Booth David J. , Bond Nick , Macreadie Peter
Published: September 2011

One of the most obvious and expected impacts of climate change is a shift in the distributional range of organisms, which could have considerable ecological and economic consequences. Australian waters are hotspots for climate-induced environmental changes; here, we review these potential changes and their apparent and potential implications for freshwater, estuarine and marine fish. Our meta-analysis detected <300 papers globally on ‘fish’ and ‘range shifts’, with ~7% being from Australia. Of the Australian papers, only one study exhibited definitive evidence of climate-induced range shifts, with most studies focussing instead on future predictions. There was little consensus in the literature regarding the definition of ‘range’, largely because of populations having distributions that fluctuate regularly. For example, many marine populations have broad dispersal of offspring (causing vagrancy). Similarly, in freshwater and estuarine systems, regular environmental changes (e.g. seasonal, ENSO cycles – not related to climate change) cause expansion and contraction of populations, which confounds efforts to detect range ‘shifts’. We found that increases in water temperature, reduced freshwater flows and changes in ocean currents are likely to be the key drivers of climate-induced range shifts in Australian fishes. Although large-scale frequent and rigorous direct surveys of fishes across their entire distributional ranges, especially at range edges, will be essential to detect range shifts of fishes in response to climate change, we suggest careful co-opting of fisheries, museum and other regional databases as a potential, but imperfect alternative.
Using species distribution models to infer potential climate change-induced range shifts of freshwater fish in south-eastern Australia
Authors: Bond Nick , Thomson Jim , Reich Paul , Stein Janet
Published: September 2011

There are few quantitative predictions for the impacts of climate change on freshwater fish in Australia. We developed species distribution models (SDMs) linking historical fish distributions for 43 species from Victorian streams to a suite of hydro-climatic and catchment predictors, and applied these models to explore predicted range shifts under future climate-change scenarios. Here, we present summary results for the 43 species, together with a more detailed analysis for a subset of species with distinct distributions in relation to temperature and hydrology. Range shifts increased from the lower to upper climate-change scenarios, with most species predicted to undergo some degree of range shift. Changes in total occupancy ranged from –38% to +63% under the lower climate-change scenario to –47% to +182% under the upper climate-change scenario. We do, however, caution that range expansions are more putative than range contractions, because the effects of barriers, limited dispersal and potential life-history factors are likely to exclude some areas from being colonised. As well as potentially informing more mechanistic modelling approaches, quantitative predictions such as these should be seen as representing hypotheses to be tested and discussed, and should be valuable for informing long-term strategies to protect aquatic biota.