bluuebunny/crossref_metadata_2025 huggingface dataset:
MicroRNA-34a regulates the longevity-associated protein SIRT1 in coronary artery disease: effect of statins on SIRT1 and microRNA-34a expression
Authors: Tabuchi Tsuyoshi , Satoh Mamoru , Itoh Tomonori , Nakamura Motoyuki
Published: February 2012

Endothelial senescence is thought to play a role in CAD (coronary artery disease). miR-34a (microRNA-34a) and other SIRT1 (silent information regulator 1)-related miRs have recently been found to target SIRT1 leading to endothelial senescence. In the present study, we investigated whether SIRT1-related miRs, including miR-9, miR-34a, miR-132, miR-181a, miR-195, miR-199a, miR-199b and miR-204, and SIRT1 were expressed in EPCs (endothelial progenitor cells) obtained from patients with CAD, and whether statins (atorvastatin or rosuvastatin) affected these levels. To determine the effects of miR-34a on SIRT1, cultured EPCs transfected with miR-34a were analysed for total SIRT1 protein levels. EPCs were obtained from 70 patients with CAD and 48 subjects without CAD. Patients with CAD were randomized to 8 months of treatment with atorvastatin or rosuvastatin. EPCs were obtained from peripheral blood at baseline and after 8 months of statin therapy. Levels of miRs and SIRT1 in EPCs were measured by real-time RT–PCR (reverse transcription–PCR) and FACS. Functional approaches to miR-34a have shown that transfection of miR-34a into EPCs resulted in regulation of SIRT1 expression. Levels of miR-34a were higher in the CAD group than in the non-CAD group, whereas levels of SIRT1 protein were lower in the CAD group than in the non-CAD group. There were no significant differences in other miRs (miR-9, miR-132, miR-181a, miR-195, miR-199a, miR-199b and miR-204) between the two groups. Levels of miR-34a were mildly negatively correlated with SIRT1 protein levels. A randomized clinical study has shown that the atorvastatin group had markedly decreased miR-34a levels and increased SIRT1 levels, whereas the rosuvastatin group showed no change in these levels. Levels of other miRs remained unchanged in the atorvastatin and rosuvastatin groups. In conclusion the results of the present study suggest that miR-34a may regulate SIRT1 expression in EPCs and that atorvastatin up-regulates SIRT1 expression via inhibition of miR-34a, possibly contributing to the beneficial effects of atorvastatin on endothelial function in CAD.
Correlation of spin and structure in doped bismuth ferrite nanoparticles
Authors: Lin J. W. , Tite Teddy , Tang Y. H. , Lue C. S. , Chang Y. M. , Lin J. G.
Published: February 2012

The mutiferroic Bi1−xEuxFeO3 nanoparticles with x = 0 to 0.4 are studied by x-ray diffraction (XRD), Raman spectra and electron spin resonance (ESR) with X-band (9.53 GHz), in order to investigate the doping effect on crystalline and spin structures. Both XRD and Raman spectrum reveal a structural transformation at x = 0.15, which is associated with the shortening of Bi—O bond length. These structural data are further related to the variation of ESR peak position and peak area, providing evidence for the enhancement of ferromagnetic coupling as x < 0.3.
Inelastic neutron scattering study of UPd2Sn
Authors: Magnani N. , Gofryk K. , Adroja D. T. , Colineau E. , Griveau J.-C. , McEwen K. A. , Kaczorowski D. , Caciuffo R.
Published: February 2012

We performed inelastic neutron scattering spectroscopy on the Heusler intermetallic compound UPd2Sn. The presence of a clear intramultiplet transition between the two lowest-lying 5f electronic states of uranium was clarified, and is consistent with predictions made in the framework of a localized-electron model. The excess molar specific heat is well reproduced by a Schottky curve corresponding to the experimentally measured energy gap if a moderately enhanced electronic contribution is taken into account.
Crystal field excitations in CeCu2Ge2: Revisited employing a single crystal and inelastic neutron scattering
Authors: Loewenhaupt Michael , Faulhaber Enrico , Schneidewind Astrid , Deppe Micha , Hradil Klaudia
Published: February 2012

The intermetallic compound, CeCu2Ge2, is the counterpart of the heavy-fermion superconductor CeCu2Si2. CeCu2Ge2 is a magnetically ordering (TN = 4.1K) Kondo lattice with a moderate Sommerfeld coefficient of 140 mJ/ molK2. Earlier inelastic neutron measurements on a polycrystalline sample revealed a doublet ground state and a quasi-quartet excited state at 16.5 meV, although a splitting of the 4f1 (J = 5/2) ground state multiplet into 3 doublets is expected from the point symmetry of the Ce3+ ions. We performed detailed inelastic neutron scattering experiments on a single crystal at the thermal triple-axis spectrometer PUMA at FRM II for different crystallographic directions. From our results we infer that the quasi-quartet, in fact, consists of two doublets at 17.0 and 18.3 meV which exhibit a strong directional dependence of their transition matrix elements to the ground state doublet. Finally, we will present a new set of crystal field parameters.
Magnetic monopole in spin pumping systems
Authors: Takeuchi Akihito , Tatara Gen
Published: February 2012

We analytically demonstrate that a magnetic monopole emerges in the spin pumping systems with the spin-orbit interaction. The magnetic monopole is a conservative quantity and is written in Maxwell’s equations in contrast with a spin current. Since the magnetic monopole current can be electrically detected via Ampere’s law for the magnetic monopole, it is a very useful concept in electromagnetically understanding spintronics.
Magnetization reversal mechanisms in 35-nm diameter Fe1-xGax/Cu multilayered nanowires
Authors: Madhukar Reddy Sai , Jin Park Jung , Maqableh Mazin M. , Flatau Alison B. , Stadler Bethanie J. H.
Published: February 2012

In this work, magnetization reversal mechanisms in various 35 nm diameter Fe80Ga20/Cu multilayered nanowire arrays were studied by a vibrating sample magnetometer (VSM) equipped with vector coils, making it possible to monitor both x- and y-components of the sample moment during reversal. When reversal fields were applied in the low angular range (0 – 60°), all nanowire structures, irrespective of Fe80Ga20 or Cu aspect ratios, experienced reversal by nucleation and propagation of a vortex domain wall. However, when fields were applied in the high angular range of 60–90°, reversal occurred by coherent rotation. Using vector-VSM, it was further shown that in structures with pancake-like Fe80Ga20 segments, the extent to which moments in adjacent segments rotate cooperatively decreased as the Cu thickness increased.
Delay detection of frequency modulation signal from a spin-torque oscillator under a nanosecond-pulsed magnetic field
Authors: Nagasawa Tazumi , Suto Hirofumi , Kudo Kiwamu , Yang Tao , Mizushima Koichi , Sato Rie
Published: February 2012

A read head composed of a spin-torque oscillator (STO) has been proposed for a hard disk drive (HDD). The STO read head senses the media field as modulation in its oscillation frequency, enabling high signal-transfer rate beyond the limit of ferromagnetic relaxation. Although frequency stability of STOs is poor because of their frequency nonlinearity, the problem of poor stability is expected to be overcome by employing delay detection. In this study, we demonstrate delay detection of the STO signals frequency-modulated by nanosecond-pulsed magnetic fields. For pulses with duration time of 1, 3, and 5 ns, we show that the phase shifts Δφ of the STO signals induced by the pulsed magnetic field are approximately proportional to the pulse area. Furthermore, output signals of delay detection are calculated using the single-shot waveforms, which show distinct pulsed forms corresponding to the respective pulsed magnetic fields.
Extraction of short time intrinsic switching field distributions in perpendicular media
Authors: Florez S. H. , Boone C. T. , Ikeda Y. , Zhu F. Q. , Takano K. , Terris B. D.
Published: February 2012

The effects of thermal fluctuations are characterized in granular perpendicular media of two different grain sizes. We extract short time switching fields Ho and intrinsic switching field distributions and find that after correcting for thermal effects and the demagnetizing fields, the switching field distributions are almost independent of grain size, in contrast to the long time scale behavior with broader distributions observed for the small grain media. In addition, the shape anisotropy fields of the magnetic clusters are shown to decrease the observed Ho and are more significant as grain size is reduced.
Quantum modification of dust shear Alfvén wave in plasmas
Authors: Jamil M. , Shahid M. , Zeba I. , Salimullah M. , Shah H. A. , Murtaza G.
Published: February 2012

The low frequency, long wavelength electromagnetic waves, viz., shear Alfvén waves in quantum dusty magnetoplasmas, have been examined using quantum magnetohydrodynamic model. The magnetized electrons and ions, quantized electrons and magnetized/unmagnetized dust give rise to a modified dispersion relation of the shear Alfvén wave. This modification is significant which is also depicted through graphical representation. The importance and relevance of the present work to the space dusty plasma environments is also pointed out.
High 5.2 peak-to-valley current ratio in Si/SiGe resonant interband tunnel diodes grown by chemical vapor deposition
Authors: Ramesh Anisha , Berger Paul R. , Loo Roger
Published: February 2012

Si/SiGe resonant interband tunnel diodes were fabricated using chemical vapor deposition (CVD) on 200-mm diameter p-doped silicon wafers. The resonant interband tunnel diode structure consists of a p+-i-n+ diode that incorporates vapor phase doped δ-doping to enhance quantum mechanical tunneling probability. The tunneling barrier thickness is varied from 2 nm to 8 nm, and a record peak-to-valley current ratio of 5.2 for a CVD process is reported for a 6 nm barrier thickness with a room temperature peak tunneling current of 20 A/cm2. The current density increases exponentially with spacer thickness reduction with a maximum value of 280 A/cm2 for a 2 nm barrier.
Non-linear plasma effects on laser-induced terahertz emission from the atmosphere
Authors: Shin J.-H. , Zhidkov A. , Jin Z. , Hosokai T. , Kodama R.
Published: February 2012

Power, spectral characteristics, and angle distribution of terahertz (THz) radiation from air irradiated by a single (ω) or coupled (ω, 2ω) femtosecond laser pulses are analyzed for higher intensities, for which non-linear plasma effects on the pulse propagation become essential, by means of multidimensional particle-in-cell simulations exploiting the self-consistent plasma kinetics. THz radiation is shown to be a result of beat waves generated at ionization front with fundamental and second harmonic waves. At lower intensities, the THz power growth is far faster than the linear; at pulse intensities over I > 1015 W/cm2, the power increases slower than the linear. Along with the forward emission, strong power in around 30o angles occurs at high intensities. Ionization of air results in poor focusing of laser pulses and, therefore, lower efficiency of THz emission.
The structure of the magnetic reconnection exhaust boundary
Authors: Liu Yi-Hsin , Drake J. F. , Swisdak M.
Published: February 2012

The structure of shocks that form at the exhaust boundaries during collisionless reconnection of anti-parallel fields is studied using particle-in-cell (PIC) simulations and modeling based on the anisotropic magnetohydrodynamic equations. Large-scale PIC simulations of reconnection and companion Riemann simulations of shock development demonstrate that the pressure anisotropy produced by counterstreaming ions within the exhaust prevents the development of classical Petschek switch-off-slow shocks (SSS). The shock structure that does develop is controlled by the firehose stability parameter ɛ=1-μ0(P‖-P⊥)/B2 through its influence on the speed order of the intermediate and slow waves. Here, P‖ and P⊥ are the pressure parallel and perpendicular to the local magnetic field. The exhaust boundary is made up of a series of two shocks and a rotational wave. The first shock takes ɛ from unity upstream to a plateau of 0.25 downstream. The condition ɛ=0.25 is special because at this value, the speeds of nonlinear slow and intermediate waves are degenerate. The second slow shock leaves ɛ=0.25 unchanged but further reduces the amplitude of the reconnecting magnetic field. Finally, in the core of the exhaust, ɛ drops further and the transition is completed by a rotation of the reconnecting field into the out-of-plane direction. The acceleration of the exhaust takes place across the two slow shocks but not during the final rotation. The result is that the outflow speed falls below that expected from the Walén condition based on the asymptotic magnetic field. A simple analytic expression is given for the critical value of ɛ within the exhaust below which SSSs no longer bound the reconnection outflow.
Interface states at the SiN/AlGaN interface on GaN heterojunctions for Ga and N-polar material
Authors: Yeluri Ramya , Swenson Brian L. , Mishra Umesh K.
Published: February 2012

Dielectric passivation is important to improve the stability and reliability of gallium nitride based semiconductor devices. We need to characterize various dielectrics and their interfaces to nitrides accurately to be able to exploit the benefits efficiently. Earlier, B. L. Swenson and U. K. Mishra [J. Appl. Phys. 106, 064902 (2009)] have detailed a photo-assisted high frequency CV characterization technique for the Ga-polar SiN/GaN interface that gives an accurate value of interface state density (Dit) across the bandgap of the dielectric. In this work, we extend the technique to study the interface states at the SiN/AlGaN interface on GaN for Ga and N polar material. This simulates the AlGaN/GaN HEMT structure. A MIS-type structure comprised of a metal on SiN on an AlGaN/GaN heterojunction was used for the study. For a structure with 1 nm AlGaN interlayer, a peak interface state density of 2.8 × 1012 cm−2 eV−1 was measured. For Ga polar devices, the measured Dit decreases with increasing AlGaN thickness. In the N-polar case, the measured Dit increases with increasing AlGaN thickness. The variations of measured Dit with AlGaN thickness, in both cases, can be explained by screening from the accumulation charge at the AlGaN/GaN interface.
Compact terahertz passive spectrometer with wideband superconductor-insulator-superconductor mixer
Authors: Kikuchi K. , Kohjiro S. , Yamada T. , Shimizu N. , Wakatsuki A.
Published: February 2012

We developed a compact terahertz (THz) spectrometer with a superconductor-insulator-superconductor (SIS) mixer, aiming to realize a portable and highly sensitive spectrometer to detect dangerous gases at disaster sites. The receiver cryostat which incorporates the SIS mixer and a small cryocooler except for a helium compressor has a weight of 27 kg and dimensions of 200 mm × 270 mm × 690 mm. In spite of the small cooling capacity of the cryocooler, the SIS mixer is successfully cooled lower than 4 K, and the temperature variation is suppressed for the sensitive measurement. By adopting a frequency sweeping system using photonic local oscillator, we demonstrated a spectroscopic measurement of CH3CN gas in 0.2–0.5 THz range.
Canonical transcorrelated theory with projected Slater-type geminals
Authors: Yanai Takeshi , Shiozaki Toru
Published: February 2012

An effective Hamiltonian perturbed with explicit interelectronic correlation is derived from similarity transformation of Hamiltonian using a unitary operator with Slater-type geminals. The Slater-type geminal is projected onto the excitation (and deexcitation) component as in the F12 theory. Simplification is made by truncating higher-body operators, resulting in a correlated Hamiltonian which is Hermitian and has exactly the same complexity as the original Hamiltonian in the second quantized form. It can thus be easily combined with arbitrary correlation models proposed to date. The present approach constructs a singularity-free Hamiltonian a priori, similarly to the so-called transcorrelated theory, while the use of the canonical transformation assures that the effective Hamiltonian is two-body and Hermite. Our theory is naturally extensible to multireference calculations on the basis of the generalized normal ordering. The construction of the effective Hamiltonian is non-iterative. The numerical assessments demonstrate that the present scheme improves the basis set convergence of the post-mean-field calculations at a similar rate to the explicitly correlated methods proposed by others that couple geminals and conventional excitations.
A family of Liouville integrable lattice equations with a parameter and its two symmetry constraints
Authors: Xu Xi-Xiang
Published: February 2012

A two-by-two matrix spectral problem with an arbitrary constant is introduced, a family of integrable lattice equations involving a parameter is derived by the technique of Lax pairs. The typical lattice equation in the obtained family is a deformed Toda lattice system. The bi-Hamiltonian structure of the obtained family of integrable lattice equations is established by using the discrete trace identity. And we prove the Liouville integrability of obtained family of integrable lattice equations. Then, Bargmann symmetry constraint and an implicit symmetry constraint of the obtained family are presented by binary nonlinearization method. Under these two symmetry constraints, we obtain two series of integrable symplectic maps and two sequences of completely integrable finite-dimensional Hamiltonian systems in Liouville sense, and every integrable lattice equation in the obtained family is decomposed by an integrable symplectic map and a completely integrable finite-dimensional Hamiltonian system. As a special case, two integrable decompositions of the deformed Toda lattice equation are given.
Spin transport in a quantum ring in the presence of Rashba spin–orbit interaction using the S-matrix method
Authors: Fallah Farhang , Esmaeilzadeh Mahdi
Published: February 2012

We study spin-dependent electron transport in a quantum ring with three leads in the presence of Rashba spin–orbit interaction using the S-matrix method. The effects of coupling between the leads and the ring on spin transport properties are taken into account. The conditions needed for perfect spin polarization, including the value of electron energy, the angles between the leads, the coupling constant of the leads and the Rashba constant are calculated, using contour maps. It is shown that total spin filtering with zero reflection is possible for low coupling constant as well as high coupling constant. In addition, we obtain the maximum value of the lead coupling constant at which perfect spin polarization can take place.
Over 100 ns intrinsic radiative recombination lifetime in type II InAs/GaAs1−xSbx quantum dots
Authors: Nishikawa Kazutaka , Takeda Yasuhiko , Yamanaka Ken-ichi , Motohiro Tomoyoshi , Sato Daisuke , Ota Junya , Miyashita Naoya , Okada Yoshitaka
Published: February 2012

We report very long intrinsic radiative recombination lifetime τrad in type II InAs quantum dots embedded in GaAs1−xSbx. The dependence of photoluminescence (PL) decay time τPL on both the Sb composition (x = 0–0.18) and excitation intensity (38–460 mW/cm2) was systematically investigated by time-resolved PL measurements with a time-correlated single-photon counting method. All PL decay curves exhibited non-exponential profiles, and τPL was strongly dependent on the excitation intensity. These properties were well explained by solving rate equations of carrier density with neglecting nonradiative process, in which τrad is inversely proportional to carrier density. The 18% Sb sample exhibited a τPL of over 100 ns under weak excitation, which is longer than twice the previously reported values. We evaluated the value of τrad in InAs/GaAs1−xSbx QDs relative to that in type I InAs/GaAs QDs based on an effective mass approximation and found that the observed extremely long τPL corresponds to τrad.
Linear and nonlinear behaviors of gyrotron backward wave oscillators
Authors: Chen Shih-Hung , Chen Liu
Published: February 2012

Linear and nonlinear behaviors of gyrotron backward wave oscillators (gyro-BWO) were investigated by both analytical theories and direct numerical calculations. Employing two-scale-length expansion, an analytical linear dispersion relation corresponding to absolute instabilities in a finite-length system has been derived. Detuning from the beam-wave resonance condition due to the finite amplitude radiation fields, meanwhile, was found to play the crucial roles in the nonlinear physics. Near the start oscillation of the gyro-BWO, the radiation field amplitude saturates when the resonance broadening is comparable to the linear growth rate. Far beyond the start oscillation threshold, the beam-wave resonance detuning effectively shortens the interaction length toward that corresponding to the critical oscillation length for the given beam current. The theoretically predicted scaling laws for the linear stability properties and nonlinear stationary states of the gyro-BWO are in good agreement with numerical results.
Study of focused-ion-beam–induced structural and compositional modifications in nanoscale bilayer systems by combined grazing incidence x ray reflectivity and fluorescence
Authors: Arac Erhan , Burn David M. , Eastwood David S. , Hase Thomas P. A. , Atkinson Del
Published: February 2012

A detailed analysis of the structural and compositional changes in NiFe/Au bilayers induced by a focused ion beam (FIB) is presented. NiFe/Au bilayers with different thickness were irradiated with a focused 30 keV Ga+ ion beam, and the evaluation of the individual layers and interfaces were investigated systematically as a function of a broad range of irradiation fluence using grazing incidence x ray reflectivity (GIXRR) and angular dependent x ray fluorescence (ADXRF) techniques carried out at synchrotron radiation sources. Experimental data were collected from 1.3 mm × 4.5 mm structures, and irradiation of such a broad areas with a 100-nm-wide focused ion beam is a challenging task. Two irradiation regimes were identified: For Ga+ fluences < 15.6 × 1014 ion/cm2 (low dose regime), the main influence of the focused ion beam is on the interface and, beyond this dose (high dose regime), sputtering effects and ion implantation becomes significant, eventually causing amorphization of the bilayer system. The broadening of the NiFe/Au interface occurs even at the lowest dose, and above a critical fluence (Φ = 1.56 × 1014 ion/cm2) can be represented by an interfacial-intermixed layer (NixFeyAu(1-x-y); x = 0.5-0.6, y = 0.1-0.15) formed between the NiFe and Au layers. The thickness of this layer increases with irradiation fluence in the low dose regime. A linear relationship is found between the squared intermixing length and irradiation fluence, indicating that FIB-induced mixing is diffusion controlled. The ballistic model fails to describe FIB-induced intermixing, indicating that thermodynamical factors, which might be originated from FIB specific features, should be taken into account. Despite the complexity of the chemical and structural formation, good agreement between the experiment and theory highlights the functionality of the combined GIXRR and ADXRF techniques for studying intermixing in high resolution.
Serpentine thermal coupling between a stream and a conducting body
Authors: Kobayashi H. , Lorente S. , Anderson R. , Bejan A.
Published: February 2012

Here we document the effect of flow configuration on the heat transfer performance of a serpentine shaped stream embedded in a conducting solid. Several configurations with fixed volume of fluid are considered: U-shaped with varying spacing between the parallel portions of the U, serpentine shapes with three elbows, and conducting soil with several parallelepipedal shapes. We show that the spacing must be greater than a critical value in order for the heat transfer density of the stream-solid configuration to be the highest that it can be. Spacings larger than this critical value do not yield improvements in heat transfer density. We also show that even though the heat transfer is time dependent, the stream-solid configuration has an effective number of heat transfer units Ntu that is nearly constant in time. The larger Ntu values correspond to the configurations with greater heat transfer density.
Self-similarity of trailing vortices
Authors: Birch David M.
Published: February 2012

Trailing vortices have been repeatedly shown to exhibit a remarkably robust self-similarity independent of the Reynolds number and upstream boundary conditions. The collapse of the inner-scaled circulation profiles of a trailing vortex has even been previously demonstrated for the cases of highly unsteady and turbulent vortex systems, as well as for vortices which were incompletely developed. A number of factors which contribute to and may artificially promote this self-similarity are discussed. It is shown that the amplitude of vortex “wandering” (or the random modulations in the vortex trajectory) observed in some experimental measurements are of sufficient amplitude to cause any arbitrary finite and axisymmetric flow structure to collapse with an idealized trailing vortex when scaled on inner parameters. It is further shown that, for the case of an incompletely developed wing-tip vortex, similarity in the outer core region may be an artefact of the rate of roll-up of the vortex sheet. Great care must, therefore, be taken when interpreting experimental measurements of vortex flows.
A new ab initio intermolecular potential energy surface and predicted rotational spectra of the Ar−H2S complex
Authors: Lei Jinping , Zhou Yanzi , Xie Daiqian
Published: February 2012

We report a reliable three-dimensional ab initio intermolecular potential energy surface for the Ar−H2S complex with H2S monomer fixed at its experimental average structure. The potential energies were evaluated using the supermolecular approach at the coupled-cluster level with a large basis set including bond functions. The full counterpoise procedure was used to correct the basis set superposition error. The potential has a planar T-shaped global minimum with a well depth of 177.48 cm−1 at the intermolecular distance of 3.72 Å. An additional planar local minimum is also found and is separated from the global minimum with an energy barrier with a height of 47.46 cm−1. The combined radial discrete variable representation/angular finite basis representation method and the Lanczos algorithm were employed to calculate the rovibrational energy levels for three isotopic species of Ar−H2S complexes (Ar−H232S, Ar−H233S, and Ar−H234S). The rotational transition frequencies and structural parameters for the three isotopomers were also determined for the ground and the first excited states, which are all in good agreement with the available experimental values.
Refractive index of sodium iodide
Authors: Jellison G. E. , Boatner L. A. , Ramey J. O. , Kolopus J. A. , Ramey L. A. , Singh D. J.
Published: February 2012

The refractive index of sodium iodide, an important scintillator material that is widely used for radiation detection, is based on a single measurement made by Spangenberg at one wavelength using the index-matching liquid immersion method (Z. Kristallogr. 57, 494 (1923)). In the present paper, we present new results for the refractive index of sodium iodide as measured by the minimum deviation technique at six wavelengths between 436 nm (n = 1.839 ± 0.002) and 633 nm (n = 1.786 ± 0.002). These six measurements can be fit to a Sellmeier model, resulting in a χ2 of 1.02, indicating a good fit to the data. In addition, we report on ellipsometry measurements, which suggest that the near-surface region of the air sensitive NaI crystal seriously degrades, even in a moisture-free environment, resulting in a significantly lower value of the refractive index near the surface. First-principles theoretical calculations of the NaI refractive index that agree with the measured values within 0.025-0.045 are also presented and discussed.
Enhanced thermoelectric performance of graphene nanoribbons
Authors: Zheng H. , Liu H. J. , Tan X. J. , Lv H. Y. , Pan L. , Shi J. , Tang X. F.
Published: February 2012

The thermoelectric properties of a series of armchair and zigzag graphene nanoribbons with narrow width are examined using nonequilibrium Green function method and molecular dynamics simulations. It is found that these nanoribbons are rather stable when the edge atoms are passivated by hydrogen and those with armchair edges exhibit much better thermoelectric performance than their zigzag counterparts. Moreover, the corresponding ZT value increases with decreasing ribbon width. By optimizing the doping level, a room temperature ZT of 6.0 can be achieved for the narrowest armchair nanoribbon. The significantly enhanced ZT value makes armchair graphene nanoribbon a promising candidate for thermoelectric applications.
Controlled electroporation of the plasma membrane in microfluidic devices for single cell analysis
Authors: Shah Duoaud , Steffen Milan , Lilge Lothar
Published: February 2012

Chemical cytometry on a single cell level is of interest to various biological fields ranging from cancer to stem cell research. The impact chemical cytometry can exert in these fields depends on the dimensionality of the retrievable analytes content. To this point, the number of different analytes identifiable and additionally their subcellular localization is of interest. To address this, we present an electroporation based approach for selective lysis of only the plasma membrane, which permits analysis of the dissolved cytoplasm, while reducing contributions from the nucleus and membrane bound fractions of the cell analytes. The use of 100 μs long pulse and a well defined DC electric field gradient of ∼4.5 kV·cm−1 generated by 3D electrodes initiates release of a cytoplasm marker in ≪1 s, while retaining nuclear fluorescence markers.
Stokes flow paths separation and recirculation cells in X-junctions of varying angle
Authors: Cachile M. , Talon L. , Gomba J. M. , Hulin J. P. , Auradou H.
Published: February 2012

Fluid and solute transfer in X-junctions between straight channels is shown to depend critically on the junction angle α in the Stokes flow regime. Experimentally, water and a water-dye solution are injected at equal flow rates in two facing channels of the junction. Planar laser induced fluorescence (PLIF) measurements show that the largest part of each injected fluid “bounces back” preferentially into the outlet channel at the lowest angle to the injection; this is opposite to the inertial case and requires a high curvature of the corresponding streamlines. The proportion of this fluid in the other channel decreases from 50% at α = 90° to 0% at a threshold angle. These counterintuitive features reflect the minimization of energy dissipation for Stokes flows. Finite elements numerical simulations of a 2D Stokes flow of equivalent geometry confirm these results and show that, below the threshold angle αc = 33.8°, recirculation cells are present in the center part of the junction and separate the two injected flows of the two solutions. Reducing further α leads to the appearance of new recirculation cells with lower flow velocities.
Do smoke-free environment policies reduce smoking on hospital grounds? Evaluation of a smoke-free health service policy at two Sydney hospitals
Authors: Poder Natasha , Carroll Therese , Wallace Cate , Hua Myna
Published: February 2012

Objective.
To evaluate the compliance of hospital staff, inpatients and visitors with Sydney South West Area Health Service’s Smoke-free Environment Policy.

Methods.
Six sites were observed at two Sydney hospitals 2 weeks before implementation of the policy and at 2 weeks, 6 months, 12 months, 18 months and 2 years after implementation.

Results.
There was an overall significant 36% (P ≤ 0.05) reduction in observed smoking incidents on hospital grounds 2 years after implementation. Two years after implementation, observed smoking incidents reduced by 44% (P ≤ 0.05) in staff, 37% (P ≤ 0.05) in visitors and remained unchanged among inpatients.

Conclusions and implications.
The Smoke-free Environment Policy was effective in reducing visitors and staff observed smoking on hospital grounds, but had little effect on inpatients’ smoking. Identifying strategies to effectively manage nicotine addiction and promote cessation amongst hospital inpatients remains a key priority.

What is known about the topic?
Smoke-free environment policies have been developed and introduced worldwide. These policies reduce tobacco use and protect the community from environmental tobacco smoke.

What does this paper add?
This paper focusses on a method used to monitor compliance of a smoke-free environment policy in a healthcare setting. The paper tracks what happened over 2 years before and after the policy was implemented. Among staff, there was evidence of compliance with the policy; however, there was no apparent change in policy compliance amongst inpatients.

What are the implications for practitioners?
Policy makers and staff implementing smoke-free policies should ensure adequate support for staff and inpatients are available, with continued promotion and enforcement of the policy. Further investigations are needed into multi-strategic cessation interventions for inpatients who smoke.
Nutritional strategies affect carcass and pork quality but have no effect on intramuscular fat content of pork
Authors: D'Souza D. N. , Mullan B. P. , Pethick D. W. , Pluske J. R. , Dunshea F. R.
Published: February 2012

Fifty crossbred (Large White × Landrace × Duroc) female finisher pigs were used to determine the effect of nutritional strategies on intramuscular fat content. The dietary treatments were (A) Control: commercial grower and finisher diet, (Day 68–166), (B) –15% P : E and –vitamin A: a 15% reduced protein : energy grower diet with no supplemental vitamin A (Day 68–110), followed by a commercial finisher diet (Day 111–166), (C) sugar: a grower diet supplemented with 10% sugar (Day 68–110), followed by a commercial finisher diet (Day 111–166), (D) zinc: a grower diet supplemented with 250 ppm zinc (Day 68–110), followed by a commercial finisher diet (Day 111–166), and (E) lecithin: a diet supplemented with 3 g/kg lecithin in the grower and finisher diet (Day 68–166). The effects of lecithin supplementation on compression characteristics of the M. semitendinosus were also studied. These data indicate that there were no significant effects of dietary manipulations on intramuscular fat content. During the grower phase (Day 68–110) pigs offered the low protein : energy and vitamin A-deficient diet had a poorer feed : gain compared with those offered diet containing supplemental sugar. Dietary lecithin supplementation decreased (P < 0.05) hardness and chewiness values for the M. semitendinosus compared with pigs offered the Control diet. Pigs offered the lecithin-supplemented diet also tended (P = 0.090) to have lower cook loss compared with pigs offered the Control diet. Dietary zinc supplementation during the grower phase improved (P < 0.05) the carcass dressing % compared with pigs offered the other diets. Dietary sugar or zinc increased (P < 0.05) the amount of lean in the belly and may be a means to control the rapid rise in the ratio of fat to lean in the belly during the finisher phase. These data indicate that dietary lecithin supplementation has the potential to improve the tenderness of pork but that intramuscular fat is difficult to manipulate nutritionally from an already moderate amount.
The quest for the function of 'Hass' avocado carbohydrates: clues from fruit and seed development as well as seed germination
Authors: Tesfay S. Z. , Bertling I. , Bower J. P. , Lovatt Carol
Published: February 2012

D-Mannoheptulose (D-manno-2-heptulose) and perseitol (D-glycero-D-manno-heptose) are unusual seven-carbon (C7) sugars that have been postulated to act as storage and transport sugars in avocado. However, thus far, there is no published evidence that satisfactorily explains the physiological functions of these carbohydrates. Various tissues at different stages of the avocado life-cycle were therefore analysed for C7 carbohydrates to derive clues on the function of the six-carbon (C6) and C7 sugars. Adult reproductive tissues (flower buds and fruit) contained significantly greater concentrations of C7 than C6 sugars, whereas in juvenile avocado tissue, the classic C6 storage carbohydrate, starch, was found only in developing and mature seeds, predominatly in the cotyledons. The dramatic increase in shoot and cotyledon C7-sugar concentrations, together with a reduction of starch reserves in the cotyledons as a result of lack of light during germination, suggests that the C6 storage carbohydrate (CHO) starch can be converted to fuel the C7 metabolism. Therefore, a changeover from C6 carbohydrate to C7 sugar metabolism characterises the progression from juvenility to maturity in avocado. Avocado seems to mirror its evolutionary development characterised by a switch-over from the common C6- to a specialised C7-sugar metabolism in the juvenile versus adult tissue. The dominance of C7 carbohydrates over C6 in adult tissues is, therefore, due to the fact that C7 sugars have multifunctional roles as a source of energy and anti-oxidants.
Genetic differentiation of the dominant perennial grass Cenchrus ciliaris L. contributes to response to water deficit in arid lands
Authors: Kharrat-Souissi Amina , Baumel Alex , Torre Franck , Chaieb Mohamed
Published: February 2012

Perennial herbaceous plants are a key element of the vegetation cover in arid lands, during a long period of the year, but their persistence depends on their ability to cope with acute drought. This characteristic could become very important with the predicted climatic changes in arid lands because the persistence of perennial plants will be a key element countering the process of desertification. The aim of the present study was to compare experimentally the response to water deficit of different genotypes of the perennial grass Cenchrus ciliaris L. (buffelgrass). We analysed the impact of water deficit on productivity, time span of the vegetative growth and leaf traits. Overall, there was highly heritable variation in the responses to applied water deficit for the measured attributes, and five different groups of genotypes responded differently to water deficit. These groups of genotypes differently invested their energy to alter their phenotype in response to water deficit. Consequently, some genotypes were more strongly affected by the water deficit and their aboveground biomass showed the largest decrease. The group of genotypes which showed the smallest decrease of their aboveground biomass was characterised by less increase of leaf hairiness, a strong decrease of leaf area and also the strongest decrease of stomatal density on the abaxial epidermis. The current study provides evidence that the capacity of C. ciliaris to regulate its growth as an adaptive mechanism under water deficit is dependent on strong genetic variation that could affect its productivity and in consequence the vegetation cover of arid ecosystems.
Calcium influx-mediated signaling is required for complete mouse egg activation
Authors: Miao Yi-Liang , Stein Paula , Jefferson Wendy N. , Padilla-Banks Elizabeth , Williams Carmen J.
Published: February 2012

Mammalian fertilization is accompanied by oscillations in egg cytoplasmic calcium (Ca
2+
) concentrations that are critical for completion of egg activation. These oscillations are initiated by Ca
2+
release from inositol 1,4,5-trisphosphate (IP
3
)-sensitive intracellular stores. We tested the hypothesis that Ca
2+
influx across the plasma membrane was a requisite component of egg activation signaling, and not simply a Ca
2+
source for store repletion. Using intracytoplasmic sperm injection (ICSI) and standard in vitro fertilization (IVF), we found that Ca
2+
influx was not required to initiate resumption of meiosis II. However, even if multiple oscillations in intracellular Ca
2+
occurred, in the absence of Ca
2+
influx, the fertilized eggs failed to emit the second polar body, resulting in formation of three pronuclei. Additional experiments using the Ca
2+
chelator, BAPTA/AM, demonstrated that Ca
2+
influx is sufficient to support polar body emission and pronucleus formation after only a single sperm-induced Ca
2+
transient, whereas BAPTA/AM-treated ICSI or fertilized eggs cultured in Ca
2+
-free medium remained arrested in metaphase II. Inhibition of store-operated Ca
2+
entry had no effect on ICSI-induced egg activation, so Ca
2+
influx through alternative channels must participate in egg activation signaling. Ca
2+
influx appears to be upstream of CaMKIIγ activity because eggs can be parthenogenetically activated with a constitutively active form of CaMKIIγ in the absence of extracellular Ca
2+
. These results suggest that Ca
2+
influx at fertilization not only maintains Ca
2+
oscillations by replenishing Ca
2+
stores, but also activates critical signaling pathways upstream of CaMKIIγ that are required for second polar body emission.
Climate change, adaptive cycles, and the persistence of foraging economies during the late Pleistocene/Holocene transition in the Levant
Authors: Rosen Arlene M. , Rivera-Collazo Isabel
Published: February 2012

Climatic forcing during the Younger Dryas (∼12.9–11.5 ky B.P.) event has become the theoretical basis to explain the origins of agricultural lifestyles in the Levant by suggesting a failure of foraging societies to adjust. This explanation however, does not fit the scarcity of data for predomestication cultivation in the Natufian Period. The resilience of Younger Dryas foragers is better illustrated by a concept of adaptive cycles within a theory of adaptive change (resilience theory). Such cycles consist of four phases: release/collapse (Ω); reorganization (α), when the system restructures itself after a catastrophic stimulus through innovation and social memory—a period of greater resilience and less vulnerability; exploitation (r); and conservation (K), representing an increasingly rigid system that loses flexibility to change. The Kebarans and Late Natufians had similar responses to cold and dry conditions vs. Early Natufians and the Pre-Pottery Neolithic A responses to warm and wet climates. Kebarans and Late Natufians (α-phase) shifted to a broader-based diet and increased their mobility. Early Natufian and Pre-Pottery Neolithic A populations (r- and K-phases) had a growing investment in more narrowly focused, high-yield plant resources, but they maintained the broad range of hunted animals because of increased sedentism. These human adaptive cycles interlocked with plant and animal cycles. Forest and grassland vegetation responded to late Pleistocene and early Holocene climatic fluctuations, but prey animal cycles reflected the impact of human hunting pressure. The combination of these three adaptive cycles results in a model of human adaptation, showing potential for great sustainability of Levantine foraging systems even under adverse climatic conditions.
Cyprus as a degraded landscape or resilient environment in the wake of colonial intrusion
Authors: Harris Sarah E.
Published: February 2012

Concerns about global warming, degradation of fragile ecosystems, and environmental and societal collapse have increased interest for lessons and/or solutions for today's environmental issues. Popular writers have turned to a classic degradation thesis of deforestation and presumed desertification within the Eastern Mediterranean as a cautionary tale of how past societies have committed ecological suicide. However, degradation and/or collapse is far more complex than the thesis permits, and uncritical adoption of such simplified stories encourages continued use of inaccurate assumptions about human–environment interaction. In Cyprus, such a degradation story materialized 150 y ago, and its promoters aimed to impress on readers their responsibility to reverse past environmental mistakes. Both the British Colonial authorities (1878–1960) and the post-Independence Cypriot government used it to justify their environmental policies. Unfortunately, this thesis was formed around several misunderstandings about Cypriot environments and society: (i) judgment of degradation without appropriate consideration of the difference between degradation and change; (ii) oversimplified representation of ruling powers and those people ruled; and (iii) denigration of the shepherd lifestyle and its presumed environmental impact. A multimethod approach using archival and field research offers a more nuanced understanding of the complexity of human–environment interaction, the underappreciated environmental and societal resilience of areas classified as degraded, and the importance of placing events within changing socioeconomic and political contexts. This study of natural resource management and environmental resilience illustrates that the practices that the colonial government viewed as unsustainable likely were sustainable.
Collapse, environment, and society
Authors: Butzer Karl W.
Published: February 2012

Historical collapse of ancient states poses intriguing social-ecological questions, as well as potential applications to global change and contemporary strategies for sustainability. Five Old World case studies are developed to identify interactive inputs, triggers, and feedbacks in devolution. Collapse is multicausal and rarely abrupt. Political simplification undermines traditional structures of authority to favor militarization, whereas disintegration is preconditioned or triggered by acute stress (insecurity, environmental or economic crises, famine), with breakdown accompanied or followed by demographic decline. Undue attention to stressors risks underestimating the intricate interplay of environmental, political, and sociocultural resilience in limiting the damages of collapse or in facilitating reconstruction. The conceptual model emphasizes resilience, as well as the historical roles of leaders, elites, and ideology. However, a historical model cannot simply be applied to contemporary problems of sustainability without adjustment for cumulative information and increasing possibilities for popular participation. Between the 14th and 18th centuries, Western Europe responded to environmental crises by innovation and intensification; such modernization was decentralized, protracted, flexible, and broadly based. Much of the current alarmist literature that claims to draw from historical experience is poorly focused, simplistic, and unhelpful. It fails to appreciate that resilience and readaptation depend on identified options, improved understanding, cultural solidarity, enlightened leadership, and opportunities for participation and fresh ideas.