bluuebunny/crossref_metadata_2025 huggingface dataset:
New Lagrangian diagnostics for characterizing fluid flow mixing
Authors: Mundel Ruty , Fredj Erick , Gildor Hezi , Rom-Kedar Vered
Published: December 2014

A new kind of Lagrangian diagnostic family is proposed and a specific form of it is suggested for characterizing mixing: the extreme (maximal/minimal) extent of a trajectory and some of its variants. It enables the detection of coherent structures and their dynamics in two- (and potentially three-) dimensional unsteady flows in both bounded and open domains. Its computation is simple and provides new insights regarding the mixing properties on both short and long time scales and on both spatial plots and distribution diagrams. We demonstrate its applicability to two dimensional flows using two toy models and a data set of surface currents from the South Atlantic.
Finite amplitude electroconvection induced by strong unipolar injection between two coaxial cylinders
Authors: Wu Jian , Vázquez Pédro A. , Traoré Philippe , Pérez Alberto T.
Published: December 2014

We perform a theoretical and numerical study of the Coulomb-driven electroconvection flow of a dielectric liquid between two coaxial cylinders. The specific case, where the inner to outer diameter ratio is 0.5, is analyzed. A strong unipolar injection of ions either from the inner or outer cylinder is considered to introduce free charge carriers into the system. A finite volume method is used to solve all governing equations including Navier-Stokes equations and a simplified set of Maxwell’s equations. The flow is characterized by a subcritical bifurcation in the finite amplitude regime. A linear stability criterion and a nonlinear one that correspond to the onset and stop of the flow motion, respectively, are linked with a hysteresis loop. In addition, we also explore the behavior of the system for higher values of the stability parameter. For inner injection, we observe a transition between the patterns made of 7 and 8 cells, before an oscillatory regime is attained. Such a transition leads to a second finite amplitude stability criterion. A simple modal analysis reveals that the competition of different modes is at the origin of this behavior. The charge density, as well as velocity field distributions is provided to help understand the bifurcation behavior.
Near-field flow structures about subcritical surface roughness
Authors: Doolittle Charles J. , Drews Scott D. , Goldstein David B.
Published: December 2014

Laminar flow over a periodic array of cylindrical surface roughness elements is simulated with an immersed boundary spectral method both to validate the method for subsequent studies and to examine how persistent streamwise vortices are introduced by a low Reynolds number roughness element. Direct comparisons are made with prior studies at a roughness-based Reynolds number Rek (=U(k) k/ν) of 205 and a diameter to spanwise spacing ratio d/λ of 1/3. Downstream velocity contours match present and past experiments very well. The shear layer developed over the top of the roughness element produces the downstream velocity deficit. Upstream of the roughness element, the vortex topology is found to be consistent with juncture flow experiments, creating three cores along the recirculation line. Streamtraces stemming from these upstream cores, however, have unexpectedly little effect on the downstream flowfield as lateral divergence of the boundary layer quickly dissipates their vorticity. Long physical relaxation time of the recirculating wake behind the roughness remains a prominent issue for simulating this type of flowfield.
Two new constraints for the cumulant matrix
Authors: Ramos-Cordoba Eloy , Salvador Pedro , Piris Mario , Matito Eduard
Published: December 2014

We suggest new strict constraints that the two-particle cumulant matrix should fulfill. The constraints are obtained from the decomposition of \documentclass[12pt]{minimal}\begin{document}$\langle \hat{S}^{\,2}\rangle$\end{document}⟨Ŝ2⟩, previously developed in our laboratory, and the vanishing number of electrons shared by two non-interacting fragments. The conditions impose stringent constraints into the cumulant structure without any need to perform an orbital optimization procedure thus carrying very small or no computational effort. These constraints are tested on the series of Piris natural orbital functionals (PNOF), which are among the most accurate ones available in the literature. Interestingly, even though all PNOF cumulants ensure correct overall \documentclass[12pt]{minimal}\begin{document}$\langle \hat{S}^{\,2}\rangle$\end{document}⟨Ŝ2⟩ values, none of them is consistent with the local spin structure of systems that dissociate more than one pair of electrons. A careful analysis of the local spin components reveals the most important missing contributions in the cumulant expression thus suggesting a means to improve PNOF5. The constraints provide an inexpensive tool for the construction and testing of cumulant structures that complement previously known conditions such as the N-representability or the square of the total spin angular momentum, \documentclass[12pt]{minimal}\begin{document}$\langle \hat{S}^{\,2}\rangle$\end{document}⟨Ŝ2⟩.
Lattice Monte Carlo simulations of polymer melts
Authors: Hsu Hsiao-Ping
Published: December 2014

We use Monte Carlo simulations to study polymer melts consisting of fully flexible and moderately stiff chains in the bond fluctuation model at a volume fraction 0.5. In order to reduce the local density fluctuations, we test a pre-packing process for the preparation of the initial configurations of the polymer melts, before the excluded volume interaction is switched on completely. This process leads to a significantly faster decrease of the number of overlapping monomers on the lattice. This is useful for simulating very large systems, where the statistical properties of the model with a marginally incomplete elimination of excluded volume violations are the same as those of the model with strictly excluded volume. We find that the internal mean square end-to-end distance for moderately stiff chains in a melt can be very well described by a freely rotating chain model with a precise estimate of the bond-bond orientational correlation between two successive bond vectors in equilibrium. The plot of the probability distributions of the reduced end-to-end distance of chains of different stiffness also shows that the data collapse is excellent and described very well by the Gaussian distribution for ideal chains. However, while our results confirm the systematic deviations between Gaussian statistics for the chain structure factor Sc(q) [minimum in the Kratky-plot] found by Wittmer et al. [EPL 77, 56003 (2007)] for fully flexible chains in a melt, we show that for the available chain length these deviations are no longer visible, when the chain stiffness is included. The mean square bond length and the compressibility estimated from collective structure factors depend slightly on the stiffness of the chains.
How to efficiently select an arbitrary Clifford group element
Authors: Koenig Robert , Smolin John A.
Published: December 2014

We give an algorithm which produces a unique element of the Clifford group on n qubits (Cn) from an integer 0≤i<Cn (the number of elements in the group). The algorithm involves O(n3) operations and provides, in addition to a canonical mapping from the integers to group elements g, a factorization of g into a sequence of at most 4n symplectic transvections. The algorithm can be used to efficiently select random elements of Cn which are often useful in quantum information theory and quantum computation. We also give an algorithm for the inverse map, indexing a group element in time O(n3).
Existence of the Stark-Wannier quantum resonances
Authors: Sacchetti Andrea
Published: December 2014

In this paper, we prove the existence of the Stark-Wannier quantum resonances for one-dimensional Schrödinger operators with smooth periodic potential and small external homogeneous electric field. Such a result extends the existence result previously obtained in the case of periodic potentials with a finite number of open gaps.
Simulated two-dimensional electronic spectroscopy of the eight-bacteriochlorophyll FMO complex
Authors: Yeh Shu-Hao , Kais Sabre
Published: December 2014

The Fenna-Matthews-Olson (FMO) protein-pigment complex acts as a molecular wire conducting energy between the outer antenna system and the reaction center; it is an important photosynthetic system to study the transfer of excitonic energy. Recent crystallographic studies report the existence of an additional (eighth) bacteriochlorophyll a (BChl a) in some of the FMO monomers. To understand the functionality of this eighth BChl, we simulated the two-dimensional electronic spectra of both the 7-site (apo form) and the 8-site (holo form) variant of the FMO complex from green sulfur bacteria, Prosthecochloris aestuarii. By comparing the spectrum, it was found that the eighth BChl can affect two different excitonic energy transfer pathways: (1) it is directly involved in the first apo form pathway (6 → 3 → 1) by passing the excitonic energy to exciton 6; and (2) it facilitates an increase in the excitonic wave function overlap between excitons 4 and 5 in the second pathway (7 → 4,5 → 2 → 1) and thus increases the possible downward sampling routes across the BChls.
Induced photoemission from driven nonadiabatic dynamics in an avoided crossing system
Authors: Arasaki Yasuki , Mizuno Yuta , Scheit Simona , Takatsuka Kazuo
Published: December 2014

When vibrational dynamics on an ionic state (large dipole moment) is coupled to that on a neutral state (small dipole moment) such as at an avoided crossing in the alkali halide system, the population transfer between the states cause oscillation of the molecular dipole, leading to dipole emission. Such dynamics may be driven by an external field. We study how the coupled wavepacket dynamics is affected by the parameters (intensity, frequency) of the driving field with the aim of making use of the photoemission as an alternative detection scheme of femtosecond and subfemtosecond vibrational and electronic dynamics or as a characteristic optical source.
An ion mobility mass spectrometer for investigating photoisomerization and photodissociation of molecular ions
Authors: Adamson B. D. , Coughlan N. J. A. , Markworth P. B. , Continetti R. E. , Bieske E. J.
Published: December 2014

An ion mobility mass spectrometry apparatus for investigating the photoisomerization and photodissociation of electrosprayed molecular ions in the gas phase is described. The device consists of a drift tube mobility spectrometer, with access for a laser beam that intercepts the drifting ion packet either coaxially or transversely, followed by a quadrupole mass filter. An ion gate halfway along the drift region allows the instrument to be used as a tandem ion mobility spectrometer, enabling mobility selection of ions prior to irradiation, with the photoisomer ions being separated over the second half of the drift tube. The utility of the device is illustrated with photoisomerization and photodissociation action spectra of carbocyanine molecular cations. The mobility resolution of the device for singly charged ions is typically 80 and it has a mass range of 100-440 Da, with the lower limit determined by the drive frequency for the ion funnels, and the upper limit by the quadrupole mass filter.
Digitized detection of gamma-ray signals concentrated in narrow time windows for transient positron annihilation lifetime spectroscopy
Authors: Kinomura A. , Suzuki R. , Oshima N. , O’Rourke B. E. , Nishijima T. , Ogawa H.
Published: December 2014

A pulsed slow-positron beam generated by an electron linear accelerator was directly used for positron annihilation lifetime spectroscopy without any positron storage devices. A waveform digitizer was introduced to simultaneously capture multiple gamma-ray signals originating from positron annihilation events during a single accelerator pulse. The positron pulse was chopped and bunched with the chopper signals also sent to the waveform digitizer. Time differences between the annihilation gamma-ray and chopper peaks were calculated and accumulated as lifetime spectra in a computer. The developed technique indicated that positron annihilation lifetime spectroscopy can be performed in a 20 μs time window at a pulse repetition rate synchronous with the linear accelerator. Lifetime spectra of a Kapton sheet and a thermally grown SiO2 layer on Si were successfully measured. Synchronization of positron lifetime measurements with pulsed ion irradiation was demonstrated by this technique.
Quantitative prediction of radio frequency induced local heating derived from measured magnetic field maps in magnetic resonance imaging: A phantom validation at 7 T
Authors: Zhang Xiaotong , Van de Moortele Pierre-Francois , Liu Jiaen , Schmitter Sebastian , He Bin
Published: December 2014

Electrical Properties Tomography (EPT) technique utilizes measurable radio frequency (RF) coil induced magnetic fields (B1 fields) in a Magnetic Resonance Imaging (MRI) system to quantitatively reconstruct the local electrical properties (EP) of biological tissues. Information derived from the same data set, e.g., complex numbers of B1 distribution towards electric field calculation, can be used to estimate, on a subject-specific basis, local Specific Absorption Rate (SAR). SAR plays a significant role in RF pulse design for high-field MRI applications, where maximum local tissue heating remains one of the most constraining limits. The purpose of the present work is to investigate the feasibility of such B1-based local SAR estimation, expanding on previously proposed EPT approaches. To this end, B1 calibration was obtained in a gelatin phantom at 7 T with a multi-channel transmit coil, under a particular multi-channel B1-shim setting (B1-shim I). Using this unique set of B1 calibration, local SAR distribution was subsequently predicted for B1-shim I, as well as for another B1-shim setting (B1-shim II), considering a specific set of parameter for a heating MRI protocol consisting of RF pulses plaid at 1% duty cycle. Local SAR results, which could not be directly measured with MRI, were subsequently converted into temperature change which in turn were validated against temperature changes measured by MRI Thermometry based on the proton chemical shift.
Development of a reduced model of formation reactions in Zr-Al nanolaminates
Authors: Vohra Manav , Winokur Justin , Overdeep Kyle R. , Marcello Paul , Weihs Timothy P. , Knio Omar M.
Published: December 2014

A computational model of anaerobic reactions in metallic multilayered systems with an equimolar composition of zirconium and aluminum is developed. The reduced reaction formalism of M. Salloum and O. M. Knio, Combust. Flame 157(2): 288–295 (2010) is adopted. Attention is focused on quantifying intermixing rates based on experimental measurements of uniform ignition as well as measurements of self-propagating front velocities. Estimates of atomic diffusivity are first obtained based on a regression analysis. A more elaborate Bayesian inference formalism is then applied in order to assess the impact of uncertainties in the measurements, potential discrepancies between predictions and observations, as well as the sensitivity of predictions to inferred parameters. Intermixing rates are correlated in terms of a composite Arrhenius law, which exhibits a discontinuity around the Al melting temperature. Analysis of the predictions indicates that Arrhenius parameters inferred for the low-temperature branch lie within a tight range, whereas the parameters of the high-temperature branch are characterized by higher uncertainty. The latter is affected by scatter in the experimental measurements, and the limited range of bilayers where observations are available. For both branches, the predictions exhibit higher sensitivity to the activation energy than the pre-exponent, whose posteriors are highly correlated.
Occupied and unoccupied electronic structure of Na doped MoS2(0001)
Authors: Komesu Takashi , Le Duy , Zhang Xin , Ma Quan , Schwier Eike F. , Kojima Yohei , Zheng Mingtian , Iwasawa Hideaki , Shimada Kenya , Taniguchi Masaki , Bartels Ludwig , Rahman Talat S. , Dowben P. A.
Published: December 2014

The influence of sodium on the band structure of MoS2(0001) and the comparison of the experimental band dispersion with density functional theory show excellent agreement for the occupied states (angle-resolved photoemission) and qualitative agreement for the unoccupied states (inverse photoemission spectroscopy). Na-adsorption leads to charge transfer to the MoS2 surface causing an effect similar to n-type doping of a semiconductor. The MoS2 occupied valence band structure shifts rigidly to greater binding with little change in the occupied state dispersion. Likewise, the unoccupied states shift downward, approaching the Fermi level, yet the amount of the shift for the unoccupied states is greater than that of the occupied states, effectively causing a narrowing of the MoS2 bandgap.
Synchronizing femtosecond laser with x-ray synchrotron operating at arbitrarily different frequencies
Authors: Jo Wonhyuk , Lee Sooheyong , Eom Intae , Landahl Eric C.
Published: December 2014

The ability to synchronize a femtosecond laser to x-ray pulses is crucial for performing ultrafast time-resolved x-ray scattering experiments at synchrotrons. Conventionally, the task has been achieved by locking a harmonic frequency of the laser oscillator to the storage ring master radio-frequency (RF). However, when the frequency mismatch between the two sources cannot be compensated by small adjustments to the laser cavity length, synchronization to a harmonic frequency requires modifying the optical components of the laser system. We demonstrate a novel synchronization scheme, which is a flexible alternative for synchronizing these two sources operating at arbitrarily different frequencies. First, we find the greatest common divisor (GCD) of the two frequencies that is still within the limited tuning range of the laser cavity length. The GCD is generated by dividing down from the storage ring RF, and is separately multiplied up to provide a feedback signal for synchronizing the laser cavity. Unique to our scheme, the GCD also serves as a harmonic RF source for the laser amplifier such that only laser oscillator pulses at fixed integer multiples of the storage ring RF are selected for amplification and delivery to experiments. Our method is implemented at the Photon Test Facility beamline of Pohang Light Source where timing-jitter less than 4 ps (r.m.s.) is measured using a new shot-to-shot method.
Confocal shift interferometry of coherent emission from trapped dipolar excitons
Authors: Repp J. , Schinner G. J. , Schubert E. , Rai A. K. , Reuter D. , Wieck A. D. , Wurstbauer U. , Kotthaus J. P. , Holleitner A. W.
Published: December 2014

We introduce a confocal shift-interferometer based on optical fibers. The presented spectroscopy allows measuring coherence maps of luminescent samples with a high spatial resolution even at cryogenic temperatures. We apply the spectroscopy onto electrostatically trapped, dipolar excitons in a semiconductor double quantum well. We find that the measured spatial coherence length of the excitonic emission coincides with the point spread function of the confocal setup. The results are consistent with a temporal coherence of the excitonic emission down to temperatures of 250 mK.
Graphene on nanoscale gratings for the generation of terahertz Smith-Purcell radiation
Authors: Tantiwanichapan Khwanchai , Wang Xuanye , Swan Anna K. , Paiella Roberto
Published: December 2014

Generation of THz radiation based on the Smith-Purcell effect in graphene is investigated numerically. The specific device geometry considered involves an electrically biased single-layer sheet of graphene deposited on a periodic array of holes in a solid substrate. Rigorous electrodynamic simulations combined with a basic model of charge transport are presented, showing that technologically significant output power levels can be obtained at geometrically tunable THz frequencies. These results suggest that graphene is a uniquely suited materials platform for the demonstration of THz electron-beam radiation mechanisms in compact solid-state systems.
Generation of metal ions in the beam plasma produced by a forevacuum-pressure electron beam source
Authors: Tyunkov A. V. , Yushkov Yu. G. , Zolotukhin D. B. , Savkin K. P. , Klimov A. S.
Published: December 2014

We report on the production of metal ions of magnesium and zinc in the beam plasma formed by a forevacuum-pressure electron source. Magnesium and zinc vapor were generated by electron beam evaporation from a crucible and subsequently ionized by electron impact from the e-beam itself. Both gaseous and metallic plasmas were separately produced and characterized using a modified RGA-100 quadrupole mass-spectrometer. The fractional composition of metal isotopes in the plasma corresponds to their fractional natural abundance.
Engineering the microstructure and magnetism of La2CoMnO6−δ thin films by tailoring oxygen stoichiometry
Authors: Galceran R. , Frontera C. , Balcells Ll. , Cisneros-Fernández J. , López-Mir L. , Roqueta J. , Santiso J. , Bagués N. , Bozzo B. , Pomar A. , Sandiumenge F. , Martínez B.
Published: December 2014

We report on the magnetic and structural properties of ferromagnetic-insulating La2CoMnO6−δ thin films grown on top of (001) SrTiO3 substrates by means of RF sputtering technique. Careful structural analysis, by using synchrotron X-ray diffraction, allows identifying two different crystallographic orientations that are closely related to oxygen stoichiometry and to the features (coercive fields and remanence) of the hysteresis loops. Both Curie temperature and magnetic hysteresis turn out to be dependent on the oxygen stoichiometry. In situ annealing conditions allow tailoring the oxygen content of the films, therefore controlling their microstructure and magnetic properties.
Strain release management in SiGe/Si films by substrate patterning
Authors: Mondiali V. , Bollani M. , Chrastina D. , Rubert R. , Chahine G. , Richard M. I. , Cecchi S. , Gagliano L. , Bonera E. , Schülli T. , Miglio L.
Published: December 2014

The nucleation and the evolution of dislocations in SiGe/Si(001) films can be controlled and confined along stripes aligned along pits carved in the substrate, leaving micrometric coherent areas free of dislocations. In this work, we have addressed the stability of such metastable areas versus, film thickness, different Ge contents (xGe = 10%–30%) and larger pit-pattern periods, revealing the flexibility and effectiveness of this method even for coherent areas of about 64 μm2. The thermal stability of such configuration has been finally verified by post-growth annealing treatment, in order to simulate device processing. Finally, μRaman spectroscopy and X-ray nanodiffraction have been used to characterize the periodic strain variations across the pattern.
Morphology and aspect ratio of bismuth nanoparticles embedded in a zinc matrix
Authors: Song Tae Eun , Wilde Gerhard , Peterlechner Martin
Published: December 2014

Nanoscale Bi particles embedded in a Zn matrix were obtained by casting and melt-spinning, resulting in quenching rate-dependent sizes and shapes. With decreasing Bi particle size, an increasing aspect ratio was observed. Due to high resolution transmission electron microscopy performed for different orientations of the nanoparticles and the matrix, the three-dimensional shape and the respective crystallographic orientations of the Bi nanoparticles as well as the orientation relationship with the matrix have been evaluated. It is suggested that the size-dependence of the nanoparticle morphologies has a strong impact on their thermal stabilities thus affecting the size dependence of the melting temperature.
Secondary compounds attenuation in Acacia macracantha leaves and its effect on intake, digestibility, plasma and productive variables by incorporating them in rations for rabbits
Authors: Espejo-Díaz M. A. , Nouel-Borges G. E.
Published: December 2014

A trial was conducted to evaluate the attenuation of secondary compounds in Uveda (Acacia macracantha) leaves at Animal Production Research Unit, Lisandro Alvarado University, Lara, Venezuela. A factorial design was used involving three water temperatures (25°C, 45°C and 65°C) × five water immersion times (0, 6, 12, 24 and 48 h). The best treatment was selected to prepare a balanced diet for rabbits with 30% inclusion of this material, to determine its effect on food intake and digestibility, plasma and productive variables compared with a basal diet especially for rabbits. Twelve New Zealand × Californian rabbits (969 ± 48 g liveweight) housed in individual cages were used for a total of 24 experimental units on a completely randomised experiment. Treatment to remove most secondary compounds involved soaking the foliage for 6 h at 25°C with led to reductions of initial total content: 70.9% total polyphenols, 77.8% simple phenols, 67.6% in total tannins, 90.4% tannins and 68.8% condensable tannins that precipitate proteins. The differences were significant for all variables (P < 0.05). Food intake was higher than the basal diet (134.9 ± 3.2 vs 107.4 ± 3.7 g/rabbit/day, P < 0.01), cell wall and hemicellulose digestibility was higher in the basal diet, whereas the apparent digestibility of dry matter, protein and energy was higher in the basal than in the Uveda diet (P < 0.01). Total cholesterol, LDL, glucose, urea and triglycerides were similar between diets, and HDL and transaminases were lower in the rabbits that consumed Uveda. The weight gain was similar between treatments (32.0 ± 1.5 g/day baseline vs 30.2 ± 1.0 g/day Uveda diet) although feed conversion was higher in the basal diet compared to the Uveda diet (3.1 ± 0.1 vs 4.1 ± 0.2, P < 0.01), with similar hot carcass weights (1294 ± 46 g vs 1206 ± 35 g). The results showed that it is feasible to include 30% of attenuated Uveda leaf in rabbit diets, resulting in weight gain and yields similar to those obtained from commercial diets and maintenance of animal health.
Effect of body mass index at parturition on goat milk quality and yield
Authors: Randby Åshild T. , Borodina Svetlana , Dønnem Ingjerd
Published: December 2014

A hypothesis that goats in high body condition (BC) at kidding produce milk with lower free fatty acid (FFA) concentrations than do goats in poor condition was tested. Dry goats were measured for neck height and bodyweight 103 days prepartum, and body mass index (BMI) was calculated as bodyweight/height2, and used as a measure of BC. One-third of the goats with the highest BMI were allocated to the ‘high-BMI’ group, and the remaining two-thirds were allocated to ‘increased-BMI’ and ‘low-BMI’ groups. Until kidding, the high and low BMI groups were offered a low-energy diet, whereas the increased-BMI group was offered a high-energy diet. After parturition, all animals were offered the same diet. The goats that attained high BMI through feeding, but not those with inherent high BMI, mobilised body fat during early lactation, and increased milk yield. Milk FFA concentrations were reduced in multiparous goats, but not in yearling goats that had another genetic status and therefore were less susceptible to high milk-FFA concentrations.
Sexual risk and healthcare seeking behaviour in young Aboriginal and Torres Strait Islander people in North Queensland
Authors: Scott Robert , Foster Regina , Oliver Lisa N. , Olsen Anna , Mooney-Somers Julie , Mathers Bradley , Micallef Joanne M. , Kaldor John , Maher Lisa
Published: December 2014

Background
Compared with non-Indigenous Australians, Aboriginal and Torres Strait Islander people have higher rates of sexually transmissible infections (STI). The identification of the sexual risk and healthcare seeking behaviours of young Aboriginal and Torres Strait Islander people in a regional Australian setting was sought. Methods: A cross-sectional survey of 155 young Aboriginal and Torres Strait Islander people (16–24 years) in Townsville was conducted. Results: Most participants (83%) reported ever having had sex, with a median age of 15 years at first sex and a range from 9 to 22 years. While young men reported more sexual partners in the last 12 months than young women, they were also more likely to report condom use at the last casual sex encounter (92% vs 68%, P = 0.006). Young women were significantly more likely than young men to report never carrying condoms (35% vs 16%); however, they were more likely to have had STI testing (53% vs 28%, P = 0.004). Of those reporting previous STI testing, 29% reported ever being diagnosed with an STI. Conclusions: The sample of young Aboriginal and Torres Strait Islander people reported an early age at first sex, variable condom use and low uptake of STI testing. The high prevalence of self-reported STI diagnoses indicate a need for opportunistic sexual health education and efforts designed to promote the uptake of STI screening in this group.
Development and validation of the Measure of Initial Attraction (MIA) / Elaboración y validación de la Medida de Atracción Inicial (MAI)
Authors: Rodrigues David , Lopes Diniz
Published: December 2014

Unilateral Initial Attraction (UIA) is a first unilateral awareness towards an unknown person and can be the starting point of an interest in voluntarily initiating an interaction or relationship. In order to create a measure tapping this feeling, Study 1 asked individuals to indicate attributes characterizing UIA (Phase 1), and to rate their centrality (Phase 2). These were used to develop the Measure of Initial Attraction (MIA) comprising one component of arousal and another of unilateral interest. While the former is shared with the love construct, the latter differentiates from measures of passion. The MIA proved to be a valid and reliable instrument with the capacity to discriminate UIA across different relationships (Study 2) and targets (Study 3), with good convergent validity (Study 3). Results are discussed within the framework of personal relationships.
Autophagy regulates the stability of sialin, a lysosomal sialic acid transporter
Authors: Huang Chengcheng , Seino Junichi , Wang Li , Haga Yoshimi , Suzuki Tadashi
Published: December 2014

Macroautophagy plays a critical role in catabolizing cytosolic components via lysosomal degradation. Recent findings from our studies indicate that basal autophagy is required for the efficient lysosomal catabolism of sialyloligosaccharides, and that the downregulation of sialin, a lysosomal transporter of sialic acids can cause a significant delay in the cytosolic accumulation of such glycans. The findings reported herein show that the sialin protein level was increased when the autophagy process was inhibited. This effect appears to be specific to sialin, since the amount of LAMP1, another lysosomal membrane protein, remains constant under the same conditions. Our results suggest that autophagy may regulate the stability of sialin, and it could lead to the cytosolic accumulation of sialyloligosaccharides in autophagy-defective cells.
Lignans from the stems and leaves of Brandisia hancei and their effects on VEGF-induced vascular permeability and migration of HRECs and DLAV formation in zebrafish
Authors: Lee Ik-Soo , Kim Young Sook , Jung Seung-Hyun , Yu Song Yi , Kim Joo-Hwan , Sun Hang , Kim Jin Sook
Published: December 2014

In our continuing search for novel antiangiogenic agents, a new lignan glycoside, (7R,8R)-1-(4-O-β-d-glucopyranosyl-3-methoxyphenyl)-2-{2-methoxy-4-[1-(E)-propene-3-ol]-phenoxyl}-propane-1,3-diol (1), along with three known lignans (2–4), were isolated from the 80% EtOH extract of Brandisia hancei stems and leaves. These isolates (1–4) were subjected to an in vitro bioassay to evaluate their effects on vascular endothelial growth factor (VEGF)-induced vascular permeability and migration of human retinal endothelial cells (HRECs). Of the compounds tested, compound 1 resulted in the greatest reduction in VEGF-induced vascular permeability by about 31.5% at 10 μM compared to the VEGF-treated control. In the migration assay, compounds 1 and 2 significantly decreased VEGF-induced HREC migration. Furthermore, zebrafish embryos treated with compounds 1 and 2 showed mild reductions of dorsal longitudinal anastomotic vessel (DLAV) formation.
Pyroglutamic acid stimulates DNA synthesis in rat primary hepatocytes through the mitogen-activated protein kinase pathway
Authors: Inoue Shinjiro , Okita Yoichi , de Toledo Andreia , Miyazaki Hiroyuki , Hirano Eiichi , Morinaga Tetsuo
Published: December 2014

We purified pyroglutamic acid from human placental extract and identified it as a potent stimulator of rat primary hepatocyte DNA synthesis. Pyroglutamic acid dose-dependently stimulated DNA synthesis, and this effect was inhibited by PD98059, a dual specificity mitogen-activated protein kinase kinase 1 (MAP2K1) inhibitor. Therefore, pyroglutamic acid stimulated DNA synthesis in rat primary hepatocytes via MAPK signaling.
Initial Characterization of Embryonic Development in North American Burbot
Authors: Egan Joshua P , Johnson Ryan D , Anders Paul J , Cain Kenneth D
Published: December 2014

Declining wild populations and increasing commercial interest are encouraging development of aquaculture methods for the North American Burbot Lota lota maculosa. A current focus of Burbot aquaculture research is reducing high mortality that is typically associated with culture of Burbot embryos and larvae. However, no Burbot embryonic or larval staging systems are currently available to provide a comparative baseline for studies of these life stages. To help address this gap, we examined Burbot embryonic development from egg fertilization until the onset of the larval period at first feeding. Ontogeny was characterized using diagnostic morphological features visible with stereo microscopy. Six developmental periods were characterized (cleavage, blastula, gastrula, segmentation, swim bladder inflation, and first feeding), along with 15 developmental stages. Water temperature ranged from 3°C to 5°C for the duration of this study. Cleavage cycles were approximately 8 h/division. Segmentation began at 12 d postfertilization (DPF) and continued until first hatch at 33 DPF. First feeding was observed at 45 DPF, 12 d after first hatch. Results presented here are expected to help refine Burbot culture methodology and research efforts aimed at conservation, management, and commercial production. Future research should use additional cohorts and expose embryos to a range of culture conditions to better understand the factors governing embryonic survival and variability in the timing of events during development.
Effect of Air Exposure and Resubmersion on the Behavior and Oxidative Stress of Pacific White Shrimp Litopenaeus vannamei
Authors: Liu Hui-Ling , Yang Shi-Ping , Wang Cheng-Gui , Chan Siu-Ming , Wang Wang-Xiong , Feng Zhen-Hua , Sun Cheng-Bo
Published: December 2014

The effect of air exposure on antioxidant activities in Pacific white shrimp Litopenaeus vannamei was studied. The behavioral changes in the shrimp and the levels of superoxide dismutase (SOD), malondialdehyde (MDA), and total antioxidant competence (T-AOC) in the muscles and hepatopancreas were determined after the shrimp were exposed to air and then resubmersed in water. Results showed that the duration of air exposure significantly influenced shrimp survival. The maximum air exposure period during which the shrimp could remain alive was 30 min. After 10 min of air exposure, the shrimp could survive when they were resubmersed in water. The T-AOC in the hepatopancreas and muscles was significantly decreased in shrimp that were exposed to air for 20 min. The MDA content in the hepatopancreas was significantly higher for the 20-, 30-, and 40-min air exposure groups than for the control group. During the resubmersion period, the MDA content in the shrimp hepatopancreas and muscles increased. For shrimp that were exposed to air for 10 min, SOD activities in the hepatopancreas and muscles were restored after 3 h of resubmersion in water. Our results indicate that air exposure can cause oxidative damage to Pacific white shrimp, but the damage can be reversed after the shrimp are resubmersed.
Task instructions determine the visuospatial and verbal–spatial nature of number–space associations
Authors: Georges Carrie , Schiltz Christine , Hoffmann Danielle
Published: December 2014

Evidence for number–space associations comes from the spatial–numerical association of response codes (SNARC) effect, consisting in faster reaction times to small/large digits with the left/right hand, respectively. Two different proposals are commonly discussed concerning the cognitive origin of the SNARC effect: the visuospatial account and the verbal–spatial account. Recent studies have provided evidence for the relative dominance of verbal–spatial over visuospatial coding mechanisms, when both mechanisms were directly contrasted in a magnitude comparison task. However, in these studies, participants were potentially biased towards verbal–spatial number processing by task instructions based on verbal–spatial labels. To overcome this confound and to investigate whether verbal–spatial coding mechanisms are predominantly activated irrespective of task instructions, we completed the previously used paradigm by adding a spatial instruction condition. In line with earlier findings, we could confirm the predominance of verbal–spatial number coding under verbal task instructions. However, in the spatial instruction condition, both verbal–spatial and visuospatial mechanisms were activated to an equal extent. Hence, these findings clearly indicate that the cognitive origin of number–space associations does not always predominantly rely on verbal–spatial processing mechanisms, but that the spatial code associated with numbers is context dependent.
Recognizing products of surfaces and simply connected 4-manifolds
Authors: Hambleton Ian , Kreck Matthias
Published: December 2014

We give necessary and sufficient conditions for a closed smooth

6
6

-manifold

N
N

to be diffeomorphic to a product of a surface

F
F

and a simply connected

4
4

-manifold

M
M

in terms of basic invariants like the fundamental group and cohomological data. Any isometry of the intersection form of

M
M

is realized by a self-diffeomorphism of

M
×
F

M \times F

.
Computing the Maslov index for large systems
Authors: Beck Margaret , Malham Simon
Published: December 2014

We address the problem of computing the Maslov index for large linear symplectic systems on the real line. The Maslov index measures the signed intersections (with a given reference plane) of a path of Lagrangian planes. The natural chart parameterization for the Grassmannian of Lagrangian planes is the space of real symmetric matrices. Linear system evolution induces a Riccati evolution in the chart. For large order systems this is a practical approach as the computational complexity is quadratic in the order. The Riccati solutions, however, also exhibit singularites (which are traversed by changing charts). Our new results involve characterizing these Riccati singularities and two trace formulae for the Maslov index as follows. First, we show that the number of singular eigenvalues of the symmetric chart representation equals the dimension of intersection with the reference plane. Second, the Cayley map is a diffeomorphism from the space of real symmetric matrices to the manifold of unitary symmetric matrices. We show the logarithm of the Cayley map equals the arctan map (modulo

2

i

2\mathrm {i}

) and its trace measures the angle of the Langrangian plane to the reference plane. Third, the Riccati flow under the Cayley map induces a flow in the manifold of unitary symmetric matrices. Using the natural unitary action on this manifold, we pullback the flow to the unitary Lie algebra and monitor its trace. This avoids singularities, and is a natural robust procedure. We demonstrate the effectiveness of these approaches by applying them to a large eigenvalue problem. We also discuss the extension of the Maslov index to the infinite dimensional case.
Culled males, infant mortality and reproductive success in a pre-industrial Finnish population
Authors: Bruckner Tim A. , Helle Samuli , Bolund Elisabeth , Lummaa Virpi
Published: December 2014

Theoretical and empirical literature asserts that the sex ratio (i.e. M/F) at birth gauges the strength of selection
in utero
and cohort quality of males that survive to birth. We report the first individual-level test in humans, using detailed life-history data, of the ‘culled cohort’ hypothesis that males born to low annual sex ratio cohorts show lower than expected infant mortality and greater than expected lifetime reproductive success. We applied time-series and structural equation methods to a unique multigenerational dataset of a natural fertility population in nineteenth century Finland. We find that, consistent with culled cohorts, a 1 s.d. decline in the annual cohort sex ratio precedes an 8% decrease in the risk of male infant mortality. Males born to lower cohort sex ratios also successfully raised 4% more offspring to reproductive age than did males born to higher cohort sex ratios. The offspring result, however, falls just outside conventional levels of statistical significance. In historical Finland, the cohort sex ratio gauges selection against males
in utero
and predicts male infant mortality. The reproductive success findings, however, provide weak support for an evolutionarily adaptive explanation of male culling
in utero
.
Diversification practices reduce organic to conventional yield gap
Authors: Ponisio Lauren C. , M'Gonigle Leithen K. , Mace Kevi C. , Palomino Jenny , de Valpine Perry , Kremen Claire
Published: December 2014

Agriculture today places great strains on biodiversity, soils, water and the atmosphere, and these strains will be exacerbated if current trends in population growth, meat and energy consumption, and food waste continue. Thus, farming systems that are both highly productive and minimize environmental harms are critically needed. How organic agriculture may contribute to world food production has been subject to vigorous debate over the past decade. Here, we revisit this topic comparing organic and conventional yields with a new meta-dataset three times larger than previously used (115 studies containing more than 1000 observations) and a new hierarchical analytical framework that can better account for the heterogeneity and structure in the data. We find organic yields are only 19.2% (±3.7%) lower than conventional yields, a smaller yield gap than previous estimates. More importantly, we find entirely different effects of crop types and management practices on the yield gap compared with previous studies. For example, we found no significant differences in yields for leguminous versus non-leguminous crops, perennials versus annuals or developed versus developing countries. Instead, we found the novel result that two agricultural diversification practices, multi-cropping and crop rotations, substantially reduce the yield gap (to 9 ± 4% and 8 ± 5%, respectively) when the methods were applied in only organic systems. These promising results, based on robust analysis of a larger meta-dataset, suggest that appropriate investment in agroecological research to improve organic management systems could greatly reduce or eliminate the yield gap for some crops or regions.
Concurrent modulation of neuronal and behavioural olfactory responses to sex and host plant cues in a male moth
Authors: Kromann Sophie H. , Saveer Ahmed M. , Binyameen Muhammad , Bengtsson Marie , Birgersson Göran , Hansson Bill S. , Schlyter Fredrik , Witzgall Peter , Ignell Rickard , Becher Paul G.
Published: December 2014

Mating has profound effects on animal physiology and behaviour, not only in females but also in males, which we show here for olfactory responses. In cotton leafworm moths,Spodoptera littoralis, odour-mediated attraction to sex pheromone and plant volatiles are modulated after mating, producing a behavioural response that matches the physiological condition of the male insect. Unmated males are attracted by upwind flight to sex pheromone released by calling females, as well as to volatiles of lilac flowers and green leaves of the host plant cotton, signalling adult food and mating sites, respectively. Mating temporarily abolishes male attraction to females and host plant odour, but does not diminish attraction to flowers. This behavioural modulation is correlated with a response modulation in the olfactory system, as shown by electro-physiological recordings from antennae and by functional imaging of the antennal lobe, using natural odours and synthetic compounds. An effect of mating on the olfactory responses to pheromone and cotton plant volatiles but not to lilac flowers indicates the presence of functionally independent neural circuits within the olfactory system. Our results indicate that these circuits interconnect and weigh perception of social and habitat odour signals to generate appropriate behavioural responses according to mating state.
Dispersal and the transition to sympatry in vertebrates
Authors: Pigot Alex L. , Tobias Joseph A.
Published: December 2014

Under allopatric speciation models, a key step in the build-up of species richness is population dispersal leading to the co-occurrence of previously geographically isolated forms. Despite its central importance for community assembly, the extent to which the transition from spatial segregation (allopatry or parapatry) to coexistence (sympatry) is a predictable process, or alternatively one governed by chance and the vagaries of biogeographic history, remains poorly understood. Here, we use estimated divergence times and current patterns of geographical range overlap among sister species to explore the evolution of sympatry in vertebrates. We show that rates of transition to sympatry vary predictably according to ecology, being faster in marine or strongly dispersive terrestrial clades. This association with organism vagility is robust to the relative frequency of geographical speciation modes and consistent across taxonomic scales and metrics of dispersal ability. These findings reject neutral models of dispersal assembly based simply on evolutionary age and are not predicted by the main alternative view that range overlap is primarily constrained by biotic interactions. We conclude that species differences in dispersal limitation are fundamental in organizing the assembly of ecological communities and shaping broad-scale patterns of biodiversity over space and time.
Effects of bottom trawling on fish foraging and feeding
Authors: Johnson Andrew Frederick , Gorelli Giulia , Jenkins Stuart Rees , Hiddink Jan Geert , Hinz Hilmar
Published: December 2014

The effects of bottom trawling on benthic invertebrates include reductions of biomass, diversity and body size. These changes may negatively affect prey availability for demersal fishes, potentially leading to reduced food intake, body condition and yield of fishes in chronically trawled areas. Here, the effect of trawling on the prey availability and diet of two commercially important flatfish species, plaice (
Pleuronectes platessa
) and dab (
Limanda limanda
), was investigated over a trawling intensity gradient in the Irish Sea. Previous work in this area has shown that trawling negatively affects the condition of plaice but not of dab. This study showed that reductions in local prey availability did not result in reduced feeding of fish. As trawling frequency increased, both fish and prey biomass declined, such that the ratio of fish to prey remained unchanged. Consequently, even at frequently trawled sites with low prey biomass, both plaice and dab maintained constant levels of stomach fullness and gut energy contents. However, dietary shifts in plaice towards energy-poor prey items were evident when prey species were analysed individually. This, together with a potential decrease in foraging efficiency due to low prey densities, was seen as the most plausible cause for the reduced body condition observed. Understanding the relationship between trawling, benthic impacts, fish foraging and resultant body condition is an important step in designing successful mitigation measures for future management strategies in bottom trawl fisheries.