bluuebunny/crossref_metadata_2025 huggingface dataset:
Gender, War and Militarism: Making and Questioning the Links
Authors: Segal Lynne
Published: April 2008

The gender dynamics of militarism have traditionally been seen as straightforward, given the cultural mythologies of warfare and the disciplining of ‘masculinity’ that occurs in the training and use of men's capacity for violence in the armed services. However, women's relation to both war and peace has been varied and complex. It is women who have often been most prominent in working for peace, although there are no necessary links between women and opposition to militarism. In addition, more women than ever are serving in many of today's armies, with feminists rather uncertain on how to relate to this phenomenon. In this article, I explore some of the complexities of applying gender analyses to militarism and peace work in sites of conflict today, looking most closely at the Israeli feminist group, New Profile, and their insistence upon the costs of the militarized nature of Israeli society. They expose the very permeable boundaries between the military and civil society, as violence seeps into the fears and practices of everyday life in Israel. I place their work in the context of broader feminist analysis offered by researchers such as Cynthia Enloe and Cynthia Cockburn, who have for decades been writing about the ‘masculinist’ postures and practices of warfare, as well as the situation of women caught up in them. Finally, I suggest that rethinking the gendered nature of warfare must also encompass the costs of war to men, whose fundamental vulnerability to psychological abuse and physical injury is often downplayed, whether in mainstream accounts of warfare or in more specific gender analysis. Feminists need to pay careful attention to masculinity and its fragmentations in addressing the topic of gender, war and militarism.
Female Fighters in the Sierra Leone War: Challenging the Assumptions?
Authors: Coulter Chris
Published: April 2008

This article looks at how the category of female fighters in the Sierra Leone civil war (1991–2002) was interpreted by the local population and by the international humanitarian community. The category of the female fighter both challenges and confuses the gendered stereotypes of ‘woman the victim’ and ‘man the perpetrator’ on multiple levels. Most research on ‘women and war’ focuses on women either as inherently more peaceful or merely as victims, and often unwittingly reproduces in ‘war-affected women’ a corresponding lack of ‘agency’. In this article, I criticize such theorizing by demonstrating the diversity and specificity of Sierra Leonean women's war experiences, while also examining how the notion of and discourse about war itself is gendered. While it has become necessary to expand the inquiries into what women do in war and to critically analyse women's roles as perpetuators and perpetrators of war and conflict, this article maintains that in situations where one can talk about the violence of women, as in the example of female combatants, one often finds violence against women as well.
A sparse matrix based full-configuration interaction algorithm
Authors: Rolik Zoltán , Szabados Ágnes , Surján Péter R.
Published: April 2008

We present an algorithm related to the full-configuration interaction (FCI) method that makes complete use of the sparse nature of the coefficient vector representing the many-electron wave function in a determinantal basis. Main achievements of the presented sparse FCI (SFCI) algorithm are (i) development of an iteration procedure that avoids the storage of FCI size vectors; (ii) development of an efficient algorithm to evaluate the effect of the Hamiltonian when both the initial and the product vectors are sparse. As a result of point (i) large disk operations can be skipped which otherwise may be a bottleneck of the procedure. At point (ii) we progress by adopting the implementation of the linear transformation by Olsen et al. [J. Chem Phys. 89, 2185 (1988)] for the sparse case, getting the algorithm applicable to larger systems and faster at the same time. The error of a SFCI calculation depends only on the dropout thresholds for the sparse vectors, and can be tuned by controlling the amount of system memory passed to the procedure. The algorithm permits to perform FCI calculations on single node workstations for systems previously accessible only by supercomputers.
Effect of the CoFe2O4 thin film thickness on multiferroic property of (00l)-oriented Pb(Zr0.5Ti0.5)O3∕CoFe2O4∕Pb(Zr0.5Ti0.5)O3 trilayer structure
Authors: Lin Rueijer , Liao Jeng-hwa , Hung Lung-jie , Wu Tai-bor
Published: April 2008

In this study, we have fabricated (00l)-oriented Pb(Zr0.5Ti0.5)O3∕CoFe2O4∕Pb(Zr0.5Ti0.5)O3 (PZT/CFO/PZT) trilayer thin films on LaNiO3 coated substrates by dual-cathode rf sputtering system. The thicknesses of top and bottom PZT thin films were fixed at 100nm but those of the CFO interlayer were 40, 80, and 120nm, respectively. The x-ray diffraction showed well-defined PZT and CFO peaks with (00l) orientation, and large grains with columnar structure were observed by field-emission scanning electron microscopy. Hard-magnetic M-H loop with a saturation magnetization of ∼235emu∕cm3 and ferroelectric hysteresis curve with saturation polarization of ∼40.1μC∕cm2 were measured at room temperature for the PZT/CFO (120 nm)/PZT trilayer thin films. Due to the low-resistance CFO interlayer in series with the PZT layers, the ferroelectric property does not significantly vary with the CFO interlayer thickness. In contrast, the possibility of the existence of nonmagnetic interfacial layer at the CFO/PZT interface causes the reduction of the magnetization. Both of the good magnetic and ferroelectric responses suggest that the (00l)-oriented PZT/CFO/PZT trilayer thin film is a promising magnetoeletric material for study.
Effects of shear flow and transverse magnetic field on Richtmyer–Meshkov instability
Authors: Cao Jintao , Wu Zhengwei , Ren Haijun , Li Ding
Published: April 2008

The effects of shear flow and transverse magnetic field on Richtmyer–Meshkov instability are examined and the expression of the interface perturbation is obtained by analytically solving the linear ideal magnetohydrodynamics equations. It shows that the perturbation evolves exponentially rather than linearly in the presence of shear flow and magnetic field when va<1−AT2δu∕2, where va is the modified Alfvén velocity, AT is the Atwood number, and δu is the relative shear velocity, respectively. The shear flow acts as a destabilizing source, while the magnetic field is a stabilizing mechanism of the shocked corrugated interface problem. The whole analysis is based on the assumption that the fluid is incompressible.
An improved analytical solution for predicting magnetic forces in permanent magnet motors
Authors: Liu Z. J. , Li J. T. , Jiang Q.
Published: April 2008

This paper describes an analytical model for analyzing magnetic forces developed in permanent magnet motors of radial field topology. The slotting effect is taken into consideration by solving the boundary value problem of the air gap field. The solution is expressed in the form of Fourier series with which the analysis of the harmonic contents in the magnetic forces can be readily performed. In particular, the curvature effect or the flux focusing effect in the slot opening regions is taken into consideration. The results of magnetic forces obtained from this model are verified with numerical simulations using the finite element method and experimental results.
The influence of ion binding and ion specific potentials on the double layer pressure between charged bilayers at low salt concentrations
Authors: Bostrom M. , Lima E. R. A. , Tavares F. W. , Ninham B. W.
Published: April 2008

Measurements of surface forces between double-chained cationic bilayers adsorbed onto molecularly smooth mica surfaces across different millimolar salt solutions have revealed a large degree of ion specificity [Pashley et al., J. Phys. Chem. 90, 1637 (1986)]. This has been interpreted in terms of highly specific anion binding to the adsorbed bilayers. We show here that inclusion in the double layer theory of nonspecific ion binding and ion specific nonelectrostatic potentials acting between ions and the two surfaces can account for the phenomenon. It also gives the right Hofmeister series for the double layer pressure.
Adsorption geometry variation of 1,4-benzenedimethanethiol self-assembled monolayers on Au(111) grown from the vapor phase
Authors: Pasquali L. , Terzi F. , Seeber R. , Doyle B. P. , Nannarone S.
Published: April 2008

1,4-benzenedimethanethiol was chemisorbed from the vapor phase onto Au(111). The chemisorption geometry, molecular orientation, and bonding properties were studied at different degrees of surface coverage by photoelectron spectroscopy, metastable deexcitation spectroscopy, and near-edge x-ray absorption fine structure spectroscopy at the carbon K edge. Two main chemisorption regimes were identified: at low coverage the molecules adopt a flat configuration, then, as the molecular density of the first layer increases, the reduction of the available chemisorption sites induces the newly bonded molecules to assume a vertical alignment, with only one of the sulphur head groups interacting with the substrate. Experimental results were interpreted on the basis of theoretical calculations that we performed on the free molecule concerning the molecular orbitals’ density of states and simulated x-ray absorption.
Interactions of the 3pπucΠu1(v=2) Rydberg-complex member in isotopic N2
Authors: Vieitez M. O. , Ivanov T. I. , de Lange C. A. , Ubachs W. , Heays A. N. , Lewis B. R. , Stark G.
Published: April 2008

The 3pπucΠu1−XΣg+1(2,0) Rydberg and b′Σu+1−XΣg+1(7,0) valence transitions of N214, N14N15, and N215 are studied using laser-based 1 extreme ultraviolet (XUV)+1′ UV two-photon-ionization spectroscopy, supplemented by synchrotron-based photoabsorption measurements in the case of N214. For each isotopomer, effective rotational interactions between the c(v=2) and b′(v=7) levels are found to cause strong Λ-doubling in c(v=2) and dramatic P∕R-branch intensity anomalies in the b′−X(7,0) band due to the effects of quantum interference. Local perturbations in energy and predissociation line width for the c(v=2) Rydberg level are observed and attributed to a spin-orbit interaction with the crossing, short-lived CΠu3(v=17) valence level.
Gel-like behavior in aggrecan assemblies
Authors: Horkay Ferenc , Basser Peter J. , Hecht Anne-Marie , Geissler Erik
Published: April 2008

Aggrecan, a large biological polyelectrolyte molecule with a bottlebrush shape, forms complexes with hyaluronic acid (HA) that provide compressive resistance in cartilage. In solutions of aggrecan alone, the concentration dependence of the osmotic pressure Π is marked by self-assembly of the molecules into aggregates. When HA is added to the solution at low aggrecan concentration c, the osmotic pressure is reduced, but in the physiological concentration range this trend is reversed. The osmotic modulus c∂Π∕∂c, which determines load bearing resistance, is enhanced in the HA-containing solutions. Dynamic light scattering (DLS) measurements show that the aggregates behave like microgels and that they become denser as the aggrecan concentration increases. The degree of densification is greatest at large distance scales in the microgels, but decreases at short distance scales. Measurements at higher resolution, involving small angle neutron scattering and small angle x-ray scattering (SAXS), confirm that at length scales shorter than 1000Å, the density is independent of the concentration and that the individual bottlebrushes in the microgels retain their identity. The absence of collective diffusion modes in the relaxation spectrum, measured by DLS and neutron spin echo, corroborates the lack of interpenetration among the aggrecan subunits in the microgel. Complexation with HA modifies the long-range spatial organization of the microgels. Comparison of the scattering pattern of the individual aggrecan molecules obtained from SAXS measurements with that of the complexes measured by DLS shows that the aggrecan-HA structure is denser and is more uniform than the random microgels. This enhanced space-filling property allows higher packing densities to be attained, thus, optimizing resistance to osmotic compression.
Electrical transport and ferromagnetism in Ga1−xMnxAs synthesized by ion implantation and pulsed-laser melting
Authors: Scarpulla M. A. , Farshchi R. , Stone P. R. , Chopdekar R. V. , Yu K. M. , Suzuki Y. , Dubon O. D.
Published: April 2008

We present a detailed investigation of the magnetic and magnetotransport properties of thin films of ferromagnetic Ga1−xMnxAs synthesized using ion implantation and pulsed-laser melting (II-PLM). The field and temperature-dependent magnetization, magnetic anisotropy, temperature-dependent resistivity, magnetoresistance, and Hall effect of II-PLM Ga1−xMnxAs films have all of the characteristic signatures of the strong p-d interaction of holes and Mn ions observed in the dilute hole-mediated ferromagnetic phase. The ferromagnetic and electrical transport properties of II-PLM films correspond to the peak substitutional Mn concentration meaning that the nonuniform Mn depth distribution is unimportant in determining the film properties. Good quantitative agreement is found with films grown by low temperature molecular beam epitaxy and having the similar substitutional MnGa composition. Additionally, we demonstrate that II-PLM Ga1−xMnxAs films are free from interstitial MnI because of the high-temperature processing. At high Mn implantation doses, the kinetics of solute redistribution during solidification alone determine the maximum resulting MnGa concentration. Uniaxial anisotropy between in-plane [1¯10] and [110] directions is present in II-PLM Ga1−xMnxAs giving evidence for this being an intrinsic property of the carrier-mediated ferromagnetic phase.
On the structure and dynamics of sheared and rotating turbulence: Direct numerical simulation and wavelet-based coherent vortex extraction
Authors: Jacobitz Frank G. , Liechtenstein Lukas , Schneider Kai , Farge Marie
Published: April 2008

The influence of rotation on the structure and dynamics of sheared turbulence is investigated using a series of direct numerical simulations. Five cases are considered: turbulent shear flow without rotation, with moderate rotation, and with strong rotation, where the rotation configuration is either parallel or antiparallel. For moderate rotation rates an antiparallel configuration increases the growth of the turbulent kinetic energy, while the parallel case reduces the growth as compared to the nonrotating case. For strong rotation rates decay of the energy is observed, linear effects dominate the flow, and the vorticity probability density functions tend to become Gaussian. Visualizations of vorticity show that the inclination angle of the vortical structures depends on the rotation rate and orientation. Coherent vortex extraction, based on the orthogonal wavelet decomposition of vorticity, is applied to split the flow into coherent and incoherent parts. It was found that the coherent part preserves the vortical structures using only a few percent of the degrees of freedom. The incoherent part was found to be structureless and of mainly dissipative nature. With increasing rotation rates, the number of wavelet modes representing the coherent vortices decreases, indicating an increased coherency of the flow. Restarting the direct numerical simulation with the filtered fields confirms that the coherent component preserves the temporal dynamics of the total flow, while the incoherent component is of dissipative nature.
Structural motifs, mixing, and segregation effects in 38-atom binary clusters
Authors: Paz-Borbón Lauro Oliver , Johnston Roy L. , Barcaro Giovanni , Fortunelli Alessandro
Published: April 2008

Thirty eight–atom binary clusters composed of elements from groups 10 and 11 of the Periodic Table mixing a second-row with a third-row transition metal (TM) (i.e., clusters composed of the four pairs: Pd–Pt, Ag–Au, Pd–Au, and Ag–Pt) are studied through a combined empirical-potential (EP)/density functional (DF) method. A “system comparison” approach is adopted in order to analyze a wide diversity of structural motifs, and the energy competition among different structural motifs is studied at the DF level for these systems, mainly focusing on the composition 24-14 (the first number refers to the second-row TM atom) but also considering selected motifs with compositions 19-19 (of interest for investigating surface segregation effects) and 32-6 (also 14-24 and 6-32 for the Pd–Au pair). The results confirm the EP predictions about the stability of crystalline structures at this size for the Au–Pd pair but with decahedral or mixed fivefold-symmetric/closed-packed structures in close competition with fcc motifs for the Ag–Au or Ag–Pt and Pd–Pt pairs, respectively. Overall, the EP description is found to be reasonably accurate for the Pd–Pt and Au–Pd pairs, whereas it is less reliable for the Ag–Au and Ag–Pt pairs due to electronic structure (charge transfer or directionality) effects. The driving force to core-shell chemical ordering is put on a quantitative basis, and surface segregation of the most cohesive element into the core is confirmed, with the exception of the Ag–Au pair for which charge transfer effects favor the segregation of Au to the surface of the clusters.
Computed lifetimes of metastable states of the NO2+ dication
Authors: Baková R. , Fišer J. , Šedivcová-Uhlíková T. , Špirko V.
Published: April 2008

Based on the ab initio potential energy, spin-orbit coupling, electronic transition dipole moment, and radial nonadiabatic coupling functions, the energy level positions, lifetimes, and radiative transition probabilities (Einstein A coefficients) have been determined for the lowest electronic states of NO2+ using the log-amplitude-phase, stabilization, and complex-scaling methods. The calculated characteristics are in reasonable agreement to the available experimental data, thus, evidencing the reliability of the theoretical predictions for the characteristics unobserved to date. With the exception of the v⩽2 vibrational states of the BΣ+2 electronic state, the calculated radiative lifetimes of the excited electronic states are longer than their predissociation lifetimes, hence, accounting for the failure of the attempts which have been made so far to observe any emission from the latter states.
Finite amplitude envelope surface solitons
Authors: Moslem W. M. , Lazar M. , Shukla P. K.
Published: April 2008

Known results on the nonlinear coupling of surface plasma waves with quasistationary ion density perturbations are generalized to include finite amplitude density modulations. A more rigorous analytical criterion is provided for the existence of the surface soliton, by using the pseudopotential formalism. Finite amplitude solutions are obtained numerically and their characteristics are discussed. The present results are useful in understanding the nonlinear dynamics and the periodic oscillatory structures on plasma surfaces.
Performance enhancement under bending of Nb3Sn strands with untwisted filaments
Authors: Muzzi L. , Corato V. , Viola R. , della Corte A.
Published: April 2008

We report on the effect of bending strain on the transport properties of multifilamentary Nb3Sn strands having twisted or untwisted superconducting filaments in order to clarify some aspects of the current transfer process within the wire cross section. Critical current measurements were performed on internal tin Nb3Sn strands, which were inserted and compacted inside thin stainless steel tubes before the heat treatment. With the application of a maximum bending strain of 0.5%, the strands with twisted filaments present a degradation of the critical current and of the n-index, while an enhancement of the performances is observed for the untwisted strands. The experimental results are interpreted in relation to the predictions of Ekin’s model.
Magnetic force microscopy of helical states in multilayer nanomagnets
Authors: Fraerman A. A. , Gribkov B. A. , Gusev S. A. , Klimov A. Yu. , Mironov V. L. , Nikitushkin D. S. , Rogov V. V. , Vdovichev S. N. , Hjorvarsson B. , Zabel H.
Published: April 2008

We have used magnetic force microscopy (MFM) to investigate noncollinear helical states in multilayer nanomagnets, consisting of a stack of single domain ferromagnetic disks separated by insulating nonmagnetic spacers. The nanomagnets were fabricated from a [Co∕Si]×3 multilayer thin film structure by electron beam lithography and ion beam etching. The structural parameters (Co layer and spacer thicknesses) were optimized to obtain a clear spiral signature in the MFM contrast, taking into account the magnetostatic interaction between the layers. MFM contrast corresponding to the helical states with different helicities was observed for the optimized structure with Co layer thicknesses of 16, 11, and 8nm, and with 3nm Si spacer thickness.
Tin (IV) phthalocyanine oxide: An air-stable semiconductor with high electron mobility
Authors: Song De , Zhu Feng , Yu Bo , Huang Lizhen , Geng Yanhou , Yan Donghang
Published: April 2008

Air-stable n-type field effect transistors were fabricated with an axially oxygen substituted metal phthalocyanine, tin (IV) phthalocyanine oxide (SnOPc), as active layers. The SnOPc thin films showed highly crystallinity on modified dielectric layer, and the electron field-effect mobility reached 0.44cm2V−1s−1. After storage in air for 32days, the mobility and on/off ratio did not obviously change. The above results also indicated that it is an effective approach of seeking n-type semiconductor by incorporating the appropriate metal connected with electron-withdrawing group into π-π conjugated system.
Three-photon absorption saturation in ZnO and ZnS crystals
Authors: Gu Bing , He Jun , Ji Wei , Wang Hui-Tian
Published: April 2008

We reported the observation of the saturation of interband three-photon absorption (3PA) in wide-gap semiconductors under intense femtosecond laser excitation. Theoretically, we developed a 3PA saturation model that is in agreement with the Z-scan experimental results. The characteristic saturation intensities were determined to be 44 and 210GW∕cm2 for ZnO and ZnS crystals, respectively. The 3PA saturation model is also consistent with the ultrafast dynamics of 3PA-generated charge carriers in ZnO and ZnS crystals, obtained from the femtosecond transient absorption measurements.
Effect of band gap on the red luminescence capability of Pr-doped InGaN layers grown by molecular beam epitaxy
Authors: Romanyuk Yaroslav E. , Kranz Lukas D. , Leone Stephen R.
Published: April 2008

The effect of In concentration on the red photoluminescence (PL) from trivalent Pr rare-earth (RE) ions in InGaN layers is investigated. A series of Pr-doped InxGa1−xN thin layers with 0⩽x⩽0.15 is grown by radio-frequency plasma-assisted molecular beam epitaxy on GaN∕sapphire templates. Photoexcitation with a He–Cd laser results in characteristic red emission at 652nm, corresponding to the P03−F23 transition of Pr3+. The Pr PL is the highest for samples grown under slightly N-rich conditions, but the “yellow luminescence” caused by Ga vacancies is also present. The intensity of the characteristic Pr PL in InxGa1−xN:Pr decreases by one order of magnitude when increasing the In content from x=0 to 0.15, even though the matching of the band gap to the Pr3+ energy states is better. Low-temperature PL measurements show that the de-excitation energy backtransfer process from excited Pr3+ ions is more severe for In-richer samples, although the amount of backtransfer cannot be the sole reason for the significant drop of the Pr3+ emission with the band gap reduction. The dissociation of bound excitons from Pr-related traps as well as the presence of In-related exciton localization centers are also likely to decrease the excitation of the Pr3+ ions. In view of ongoing efforts to search for efficient RE-doped III-V emitters, the results indicate that the formation∕dissociation rate of RE-bound excitons is one of the key factors that determine the RE emission yield.
Morphological instability of Cu nanolines induced by Ga+-ion bombardment: In situ scanning electron microscopy and theoretical model
Authors: Wei Qiangmin , Li Weixing , Sun Kai , Lian Jie , Wang Lumin
Published: April 2008

The morphological evolution of copper nanolines induced by focused ion beam at normal bombardment has been investigated by in situ scanning electron microscopy. A periodic array of particles is observed when the width of lines reaches a certain value. The stability of a nanoline is studied in terms of a model based on Nichols and Mullins [Trans. Metall. Soc. AIME 233, 1840 (1965)] instability and curvature-dependent sputtering yield. A critical line width is found by linear analysis. When the line width is below this value, unstable mode whose wave vector is parallel to the line axis develops and a chain of periodic particles forms. When the width is above this critical value, the sputtering etching only leads to the decrease of width. The flux and temperature dependence of wavelength is measured and explained based on this model. The predictions of the model are in good agreement with the experimental results.
Improved transport and photostability of poly(methoxy-ethylexyloxy-phenylenevinilene) polymer thin films by boron doped freestanding silicon nanocrystals
Authors: Švrček Vladimir , Fujiwara Hiroyuki , Kondo Michio
Published: April 2008

We report on an improvement of optoelectrical properties of poly(methoxy-ethylexyloxy-phenylenevinilene) (MEH-PPV) polymer by incorporation of boron doped freestanding silicon nanocrystals (Si-ncs). The photoluminescence (PL) behavior of blended Si-ncs could be assigned to quantum confinement of excitons in nanocrystallites with the energy band gap around ∼2.2eV. Low temperature PL at low excitation intensities reveals the presence of boron in Si-ncs. The photoconductivity measurements showed that the light absorption in the Si-nc/MEH-PPV films lead to a charge separation. The presence of the Si-ncs in the film increases the carrier transport, avoids oxygen diffusion, and significantly improves the photostability of the composite.
Tuning of biased domain wall depinning fields at Permalloy nanoconstrictions
Authors: Faulkner C. C. , Allwood D. A. , Cowburn R. P.
Published: April 2008

The propagation of a transverse domain wall (DW) through single asymmetric nanoconstrictions is investigated in continuous ferromagnetic planar wire structures, by localized magneto-optical Kerr effect magnetometry. Using focused ion beam (FIB) milled planar Permalloy nanowires, we propagate a DW in opposite directions through single asymmetric nanoconstriction. The DW depinning field from an asymmetric nanoconstriction strongly depends on the direction of motion of the DW relative to the trap. A depinning field bias effect is tuned by varying the constriction width from 50to200nm in 300nm wide nanowires. FIB milled nanoconstrictions, with a width as narrow as 50nm, demonstrate a bias effect. Narrowing the width of the constriction enhances the depinning field bias effect.
Improvement of light extraction from GaN-based thin-film light-emitting diodes by patterning undoped GaN using modified laser lift-off
Authors: Bao Kui , Kang Xiang Ning , Zhang Bei , Dai Tao , Sun Yong Jian , Fu Qiang , Lian Gui Jun , Xiong Guang Cheng , Zhang Guo Yi , Chen Yong
Published: April 2008

To improve light extraction from GaN-based light-emitting diodes (LEDs), we demonstrated an approach of modified laser lift-off (M-LLO) technique for patterning undoped GaN (u-GaN). The M-LLO consists in sequentially forming a two-dimensional triangular lattice pattern with a 4μm period on a polymer layer over a sapphire substrate backplane by UV imprint and delivering the pattern onto u-GaN accompanied with the removal of the sapphire substrate. The enhancement of light extraction from GaN-based M-LLO LED with a reflective Ag film on the 120nm deep u-GaN pattern was about 31% and 100% compared to that of a LLO-LED with a reflective film and a conventional LED with a sapphire substrate, respectively.
Line-narrowed, compact, and coherent source of widely tunable terahertz radiation
Authors: Stothard D. J. M. , Edwards T. J. , Walsh D. , Thomson C. L. , Rae C. F. , Dunn M. H. , Browne P. G.
Published: April 2008

We report a technique for line-narrowing terahertz radiation produced through parametric generation. By incorporating an etalon within the idler-wave cavity of the parametric oscillator, radiation is generated with a linewidth of 1GHz (freerunning linewidth 50–100GHz) and with a center frequency continuously tunable over a band >50GHz, settable anywhere within the coarse tuning range of the device (1–3THz). When implemented within an intracavity cavity geometry, pulses of terahertz radiation of duration ∼10ns and energy ∼30nJ are generated at repetition rates up to 400Hz (implying mean powers of >10μW and peak powers of ∼3W) in a compact device.
Steady state photoinduced absorption of PbS quantum dots film
Authors: Zhang Jian , Jiang Xiaomei
Published: April 2008

We have measured steady state photoinduced absorption (PIA) of PbS quantum dot (QD) film in an energy range of interband electronic transitions at low temperature. PIA spectra show both positive and negative PIAs corresponding to five consecutive interband transitions. The close resemblance between PIA spectrum and the second derivative of the linear optical absorption strongly suggests that these steady state PIAs may be caused by photoinduced local electric field, i.e., the linear Stark effect. We postulate this local electric field be generated by the trapped charges under laser excitations.
Piezoelectric properties and structural phase transitions of naturally polarized (Na0.75K0.25Bi)0.5TiO3 crystal
Authors: Zhao M. L. , Yi X. J. , Wang C. L. , Zhang J. L. , Wang J. F. , Li J. C.
Published: April 2008

Electrical properties of a naturally polarized (Na0.75K0.25Bi)0.5TiO3 crystal have been investigated over a broad range of temperatures. Noticeable piezoelectric resonance signals have been observed up to 540°C. Based on the piezoelectric measurement, we suggest a R3c-P4bm-Pm3¯m sequence of structural phase transitions in this crystal. Moreover, at temperatures above 520°C, mobile sodium ions in the crystal are proposed to contribute to the electrical conduction; they have an activation energy of 2.06eV. This migration of Na+ at high temperatures can explain the naturally generated piezoelectricity in (Na0.75K0.25Bi)0.5TiO3 crystal.
Field emission enhancement by the quantum structure in an ultrathin multilayer planar cold cathode
Authors: Wang R. Z. , Yan H. , Wang B. , Zhang X. W. , Hou X. Y.
Published: April 2008

Field electron emission (FE) from an ultrathin multilayer planar cold cathode (UMPC) including a quantum well structure has been both experimentally and theoretically investigated. We found that by tuning the energy levels of UMPC, the FE characteristic can be evidently improved, which is unexplained by conventional FE mechanism. FE emission mechanism, dependent on the quantum structure effect, which supplies a favorable location of electron emission and enhances tunneling ability, has been presented to expound the notable amelioration. An approximate formula, brought forward, can predict the quantum FE enhancement, in which the theoretical prediction is close to the experimental result.
Desorption-induced first-order phase transition in a cyano-bridged compound
Authors: Moritomo Y. , Nakada F. , Kamioka H. , Kim J. E. , Takata M.
Published: April 2008

The guest-host interaction is one of the promising tools to control the material state. Here, we found that a cyano-bridged compound Na0.50Co[Fe(CN)6]0.723.8H2O shows a first-order structural phase transition below a critical pressure Pc (150Pa) at 300K. Judging from suppression of the OH stretching mode in the infrared spectra, we ascribed the phase transition to desorption of the ligand waters. The phase transition accompanies a significant change of the visible absorption spectra, reflecting the strong hybridization between the Coeg state and the CNσ states.
High crop productivity with high water use in winter and summer on the Liverpool Plains, eastern Australia
Authors: Young R. R. , Derham P.-J. , Dunin F. X. , Bernardi A. L. , Harden S.
Published: April 2008

We report exceptional productivity and associated water-use efficiency across seasons for commercial crops of rainfed spring wheat and grain sorghum growing on stored soil water in Vertosols on the Liverpool Plains, central-eastern Australia. Agreement between the independently measured terms of evapotranspiration (ET) and the soil water balance (in-crop rainfall + δsoil water) was achieved within acceptable uncertainty across almost all measurement intervals, to provide a reliable dataset for the analysis of growth and water-use relationships without the confounding influence of water outflow either overland or within the soil. Post-anthesis intrinsic transpiration efficiency (kc
) values of 4.7 and 7.2 Pa for wheat and sorghum, respectively, and grain yields of 8 and 7 t/ha from ET of 450 and 442 mm (1.8 and 1.6 g/m2.mm), clearly demonstrate the levels of productivity and water-use efficiency possible for well-managed crops within an intensive and productive response cropping sequence. The Vertosols in which the crops were grown enabled rapid and apparently unconstrained delivery of significant quantities of subsoil water (34% and 51% of total available) after anthesis, which enabled a doubling of pre-anthesis standing biomass and harvest indices of almost 50%. Durum wheat planted into only 0.30 m of moist soil and enduring lower than average seasonal rainfall, yielded less biomass and grain (2.3 t/ha) with lower water-use efficiency (0.95 g/m2.mm) but larger transpiration efficiency, probably due to reduced stomatal conductance. We argue that crop planting in response to stored soil water and management for high water-use efficiency to achieve high levels of average productivity of crop sequences over time can have a significant effect on both increased productivity and enhanced hydrological stability across alluvial landscapes.
Use of garden organic compost in vegetable production under contrasting soil P status
Authors: Chan K. Y. , Dorahy C. , Wells T. , Fahey D. , Donovan N. , Saleh F. , Barchia I.
Published: April 2008

Little research has been carried out on the agronomic value of compost produced from garden organics for vegetable production. A field experiment was established in Camden, near Sydney, Australia, to (i) evaluate the effect of the compost on vegetable production and soil quality relative to conventional practice, (ii) compare vegetable production under high and low soil P status, and (iii) monitor the changes in soil P concentration under two compost treatments relative to conventional farmers’ practice. After three successive crops (broccoli, eggplant and cabbage), results indicate that compost (120 dry t/ha) and half-compost (60 dry t/ha supplemented by inorganic fertilisers) treatments can produce similar yield to the conventional practice of using a mixture of poultry manure and inorganic fertiliser. Furthermore, similar yields were achieved for three different crops grown under high and low P soil conditions, clearly demonstrating that the high extractable soil P concentrations currently found in the vegetable farms of Sydney are not necessary for maintaining productivity. The compost treatments also significantly increased soil organic carbon and soil quality including soil structural stability, exchangeable cations, and soil biological properties. Importantly, the compost treatment was effective in reducing the rate of accumulation of extractable soil P compared with the conventional vegetable farming practice. Our results highlight the potential for using compost produced from source separated garden organics in reversing the trend of soil degradation observed under current vegetable production, without sacrificing yield.
Dual-purpose canola—a new opportunity in mixed farming systems
Authors: Kirkegaard J. A. , Sprague S. J. , Dove H. , Kelman W. M. , Marcroft S. J. , Lieschke A. , Howe G. N. , Graham J. M.
Published: April 2008

The term dual-purpose canola describes the use of a canola crop for forage before seed production. It could potentially provide a profitable and flexible break-crop option for mixed farms, but there have been no studies to test the concept in Australia. We investigated the feasibility of using canola in this way in field experiments near Canberra, Australia, from 2004 to 2006, using European winter and mid–late maturing Australian spring canola varieties. Winter varieties sown from early March to mid-April produced 2.5–5.0 t/ha of biomass providing 0.3–3.5 t/ha of high-quality forage grazed by sheep in winter. The spring varieties produced similar amounts of vegetative biomass from April sowing but were unsuited to the earlier March sowing as they flowered in early winter and did not recover from grazing. The canola forage was readily eaten by sheep; alkane-based estimates of diet composition indicated that >85% of the organic matter intake consisted of canola. Canola forage was also highly digestible (86–88%) and Merino hoggets grew at 210 g/day from a dry matter intake of 1530 g DM/day. The canola generally recovered well when grazed in winter before bud elongation. Delays in flowering associated with heavy grazing ranged from 0 to 4 days when grazed before buds were visible, to 28 days if the crop had commenced flowering. Significant delays in flowering (>14 days) associated with winter grazing did not reduce seed yield or oil content when favourable spring conditions allowed compensatory growth. Yield loss was observed when winter and spring conditions were unfavourable for compensatory growth, or if grazing continued too late into spring (late September) irrespective of seasonal conditions. The yield loss was more than offset by the value of the grazed forage and the mean gross margin for dual-purpose canola over the four experiments was $240 to $500 higher than for grain-only canola depending on the value assumed for the forage. The study indicates there is considerable scope to capture value from grazing early-sown canola crops during winter without significant, uneconomic trade-offs with seed yield. Further investigations in other medium to high rainfall environments in southern Australia are warranted.
Testing the primer-plant concept: wheat yields can be increased on alkaline sodic soils when an effective primer phase is used
Authors: Nuttall J. G. , Davies S. L. , Armstrong R. A. , Peoples M. B.
Published: April 2008

The primer-plant concept was tested for wheat (Triticum aestivum) grown on an alkaline sodic soil taken from the southern Mallee of Victoria. This concept relates to use of species of plants with high natural adaptation to hostile subsoils, being able to modify the soil environment and leave biopores for the benefit of subsequent annual crops. For the experiment reported here, wheat was sown into large (0.3 m diam. by 1.0 m length) intact soil cores (collected from a cropping paddock near Birchip in the southern Mallee region of Victoria, Australia) following either birdsfoot trefoil (Lotus corniculatus), canola (Brassica napus), chicory (Cichorium intybus), lucerne (Medicago sativa), safflower (Carthamus tinctorius), sulla (Hedysarum coronarium), or tall wheatgrass (Thinopyrum ponticum). At the conclusion of the priming phase [270 days after sowing (DAS)], all the different crops extracted c. 145 mm of stored water, the exception being canola (120 mm). Lucerne and birdsfoot trefoil produced the least above-ground biomass (26 g/pot), and safflower the most (115 g/pot). Greater early vigour and water extraction (49 mm) occurred for subsequent wheat crops after birdsfoot trefoil than with wheat after all other species (39 mm). This translated to a 15% yield advantage for wheat after birdsfoot trefoil compared with lucerne. Wheat after sulla yielded 12% more due to increased grain number and kernel size compared with wheat after lucerne. It was proposed that the difference in yield related to the root systems of species tested. Birdsfoot trefoil and sulla were characterised by intensive branching, which potentially produced a fine mosaic of residual biopores. Lucerne, in contrast, which was assumed to have similar break-crop effects, had a large taproot with fewer branches leaving fewer, larger residual root channels than either of the other legumes. It is believed that the fine biopores allowed more rapid and thorough exploration of the bulk soil by the crop roots.
Acute corticosterone treatment is sufficient to induce anxiety and amygdaloid dendritic hypertrophy
Authors: Mitra Rupshi , Sapolsky Robert M.
Published: April 2008

Stress is known to induce dendritic hypertrophy in the basolateral amygdala (BLA) and to enhance anxiety. Stress also leads to secretion of glucocorticoids (GC), and the BLA has a high concentration of glucocorticoid receptors. This raises the possibility that stress-induced elevation in GC secretion might directly affect amygdaloid neurons. To address the possible effects of GC on neurons of amygdala and on anxiety, we used rats treated either acutely with a single dose or chronically with 10 daily doses of high physiological levels of corticosterone (the rat-specific glucocorticoid). Behavior and morphological changes in neurons of BLA were measured 12 days after the initiation of treatment in both groups. A single acute dose of corticosterone was sufficient to induce dendritic hypertrophy in the BLA and heightened anxiety, as measured on an elevated plus maze. Moreover, this form of dendritic hypertrophy after acute treatment was of a magnitude similar to that caused by chronic treatment. Thus, plasticity of BLA neurons is sufficiently sensitive so as to be saturated by a single day of stress. The effects of corticosterone were specific to anxiety, as neither acute nor chronic treatment caused any change in conditioned fear or in general locomotor activity in these animals.
Complex interplays among population dynamics, environmental forcing, and exploitation in fisheries
Authors: Rouyer T. , Fromentin J.-M. , Ménard F. , Cazelles B. , Briand K. , Pianet R. , Planque B. , Stenseth N. C.
Published: April 2008

The patterns of variations in fisheries time series are known to result from a complex combination of species and fisheries dynamics all coupled with environmental forcing (including climate, trophic interactions, etc.). Disentangling the relative effects of these factors has been a major goal of fisheries science for both conceptual and management reasons. By examining the variability of 169 tuna and billfish time series of catch and catch per unit effort (CPUE) throughout the Atlantic as well as their linkage to the North Atlantic Oscillation (NAO), we find that the importance of these factors differed according to the spatial scale. At the scale of the entire Atlantic the patterns of variations are primarily spatially structured, whereas at a more regional scale the patterns of variations were primarily related to the fishing gear. Furthermore, the NAO appeared to also structure the patterns of variations of tuna time series, especially over the North Atlantic. We conclude that the patterns of variations in fisheries time series of tuna and billfish only poorly reflect the underlying dynamics of these fish populations; they appear to be shaped by several successive embedded processes, each interacting with each other. Our results emphasize the necessity for scientific data when investigating the population dynamics of large pelagic fishes, because CPUE fluctuations are not directly attributable to change in species' abundance.
Cytidine deamination induced HIV-1 drug resistance
Authors: Mulder Lubbertus C. F. , Harari Ariana , Simon Viviana
Published: April 2008

The HIV-1 Vif protein is essential for overcoming the antiviral activity of DNA-editing apolipoprotein B mRNA editing enzyme, catalytic polypeptide 3 (APOBEC3) cytidine deaminases. We show that naturally occurring HIV-1 Vif point mutants with suboptimal anti-APOBEC3G activity induce the appearance of proviruses with lamivudine (3TC) drug resistance-associated mutations before any drug exposure. These mutations, ensuing from cytidine deamination events, were detected in >40% of proviruses with partially defective Vif mutants. Transfer of drug resistance from hypermutated proviruses via recombination allowed for 3TC escape under culture conditions prohibitive for any WT viral growth. These results demonstrate that defective hypermutated genomes can shape the phenotype of the circulating viral population. Partially active Vif alleles resulting in incomplete neutralization of cytoplasmic APOBEC3 molecules are directly responsible for the generation of a highly diverse, yet G-to-A biased, proviral reservoir, which can be exploited by HIV-1 to generate viable and drug-resistant progenies.
Calcium sensitivity of the cross-bridge cycle of Myo1c, the adaptation motor in the inner ear
Authors: Adamek Nancy , Coluccio Lynne M. , Geeves Michael A.
Published: April 2008

The class I myosin Myo1c is a mediator of adaptation of mechanoelectrical transduction in the stereocilia of the inner ear. Adaptation, which is strongly affected by Ca
2+
, permits hair cells under prolonged stimuli to remain sensitive to new stimuli. Using a Myo1c fragment (motor domain and one IQ domain with associated calmodulin), with biochemical and kinetic properties similar to those of the native molecule, we have performed a thorough analysis of the biochemical cross-bridge cycle. We show that, although the steady-state ATPase activity shows little calcium sensitivity, individual molecular events of the cross-bridge cycle are calcium-sensitive. Of significance is a 7-fold inhibition of the ATP hydrolysis step and a 10-fold acceleration of ADP release in calcium. These changes result in an acceleration of detachment of the cross-bridge and a lengthening of the lifetime of the detached M–ATP state. These data support a model in which slipping adaptation, which reduces tip-link tension and allows the transduction channels to close after an excitatory stimulus, is mediated by Myo1c and modulated by the calcium transient.
Hybrid alphavirus–rhabdovirus propagating replicon particles are versatile and potent vaccine vectors
Authors: Rose Nina F. , Publicover Jean , Chattopadhyay Anasuya , Rose John K.
Published: April 2008

Self-propagating, infectious, virus-like particles are generated in animal cell lines transfected with a Semliki Forest virus RNA replicon encoding a single viral structural protein, the vesicular stomatitis virus (VSV) glycoprotein. We show here that these infectious particles, which we call propagating replicons, are potent inducers of neutralizing antibody in animals yet are nonpathogenic. Mice vaccinated with a single dose of the particles generated high titers of VSV-neutralizing antibody and were protected from a subsequent lethal challenge with VSV. Induction of antibody required RNA replication. We also report that additional genes (including an HIV-1 envelope protein gene) expressed from the propagating replicons induced strong cellular immune responses to the corresponding proteins after a single inoculation. Our studies reveal the potential of these particles as simple and safe vaccine vectors inducing strong humoral and cellular immune responses.