bluuebunny/crossref_metadata_2025 huggingface dataset:
Biased diffusion in three-dimensional comb-like structures
Authors: Berezhkovskii Alexander M. , Dagdug Leonardo , Bezrukov Sergey M.
Published: April 2015

In this paper, we study biased diffusion of point Brownian particles in a three-dimensional comb-like structure formed by a main cylindrical tube with identical periodic cylindrical dead ends. It is assumed that the dead ends are thin cylinders whose radius is much smaller than both the radius of the main tube and the distance between neighboring dead ends. It is also assumed that in the main tube, the particle, in addition to its regular diffusion, moves with a uniform constant drift velocity. For such a system, we develop a formalism that allows us to derive analytical expressions for the Laplace transforms of the first two moments of the particle displacement along the main tube axis. Inverting these Laplace transforms numerically, one can find the time dependences of the two moments for arbitrary values of both the drift velocity and the dead-end length, including the limiting case of infinitely long dead ends, where the unbiased diffusion becomes anomalous at sufficiently long times. The expressions for the Laplace transforms are used to find the effective drift velocity and diffusivity of the particle as functions of its drift velocity in the main tube and the tube geometric parameters. As might be expected from common-sense arguments, the effective drift velocity monotonically decreases from the initial drift velocity to zero as the dead-end length increases from zero to infinity. The effective diffusivity is a more complex, non-monotonic function of the dead-end length. As this length increases from zero to infinity, the effective diffusivity first decreases, reaches a minimum, and then increases approaching a plateau value which is proportional to the square of the particle drift velocity in the main tube.
Natural scaling of size distributions in homogeneous and heterogeneous rate equations with size-linear capture rates
Authors: Dubrovskii V. G. , Berdnikov Yu. S.
Published: April 2015

We obtain exact solutions of the rate equations for homogeneous and heterogeneous irreversible growth models with linear size dependences of the capture rates. In the limit of high ratios of diffusion constant over deposition rate, both solutions yield simple analytical scaling functions with the correct normalizations. These are given by the cumulative distribution function and the probability density function of the gamma-distribution in homogeneous and heterogeneous cases, respectively. Our size distributions depend on the value of the capture rate a in the reaction of joining two mobile monomers A1 (A1 + A1 → A2) or the monomer attachment to the reactive defect B (A1 + B → AB). In homogeneous cases, the size distribution is monotonically decreasing regardless of a. In heterogeneous growth, the distribution is monotonically decreasing when a ≤ 1 and monomodal when a > 1. The obtained solutions describe fairly well the experimental data on the length distributions of Al, Ga, In, and Mn adatom chains on Si(100)-2 × 1 surfaces.
Estimation of channel mismatches in time-interleaved analog-to-digital converters based on fractional delay and sine curve fitting
Authors: Guo Lianping , Tian Shulin , Jiang Jun
Published: April 2015

This paper proposes an algorithm to estimate the channel mismatches in time-interleaved analog-to-digital converter (TIADC) based on fractional delay (FD) and sine curve fitting. Choose one channel as the reference channel and apply FD to the output samples of reference channel to obtain the ideal samples of non-reference channels with no mismatches. Based on least square method, the sine curves are adopted to fit the ideal and the actual samples of non-reference channels, and then the mismatch parameters can be estimated by comparing the ideal sine curves and the actual ones. The principle of this algorithm is simple and easily understood. Moreover, its implementation needs no extra circuits, lowering the hardware cost. Simulation results show that the estimation accuracy of this algorithm can be controlled within 2%. Finally, the practicability of this algorithm is verified by the measurement results of channel mismatch errors of a two-channel TIADC prototype.
Simulation of the elementary evolution operator with the motional states of an ion in an anharmonic trap
Authors: Santos Ludovic , Justum Yves , Vaeck Nathalie , Desouter-Lecomte M.
Published: April 2015

Following a recent proposal of L. Wang and D. Babikov [J. Chem. Phys. 137, 064301 (2012)], we theoretically illustrate the possibility of using the motional states of a Cd+ ion trapped in a slightly anharmonic potential to simulate the single-particle time-dependent Schrödinger equation. The simulated wave packet is discretized on a spatial grid and the grid points are mapped on the ion motional states which define the qubit network. The localization probability at each grid point is obtained from the population in the corresponding motional state. The quantum gate is the elementary evolution operator corresponding to the time-dependent Schrödinger equation of the simulated system. The corresponding matrix can be estimated by any numerical algorithm. The radio-frequency field which is able to drive this unitary transformation among the qubit states of the ion is obtained by multi-target optimal control theory. The ion is assumed to be cooled in the ground motional state, and the preliminary step consists in initializing the qubits with the amplitudes of the initial simulated wave packet. The time evolution of the localization probability at the grids points is then obtained by successive applications of the gate and reading out the motional state population. The gate field is always identical for a given simulated potential, only the field preparing the initial wave packet has to be optimized for different simulations. We check the stability of the simulation against decoherence due to fluctuating electric fields in the trap electrodes by applying dissipative Lindblad dynamics.
A phase match based frequency estimation method for sinusoidal signals
Authors: Shen Yan-Lin , Tu Ya-Qing , Chen Lin-Jun , Shen Ting-Ao
Published: April 2015

Accurate frequency estimation affects the ranging precision of linear frequency modulated continuous wave (LFMCW) radars significantly. To improve the ranging precision of LFMCW radars, a phase match based frequency estimation method is proposed. To obtain frequency estimation, linear prediction property, autocorrelation, and cross correlation of sinusoidal signals are utilized. The analysis of computational complex shows that the computational load of the proposed method is smaller than those of two-stage autocorrelation (TSA) and maximum likelihood. Simulations and field experiments are performed to validate the proposed method, and the results demonstrate the proposed method has better performance in terms of frequency estimation precision than methods of Pisarenko harmonic decomposition, modified covariance, and TSA, which contribute to improving the precision of LFMCW radars effectively.
Surveying the free energy landscapes of continuum models: Application to soft matter systems
Authors: Kusumaatmaja Halim
Published: April 2015

A variety of methods are developed for characterising the free energy landscapes of continuum, Landau-type free energy models. Using morphologies of lipid vesicles and a multistable liquid crystal device as examples, I show that the methods allow systematic study of not only the most relevant minimum energy configurations, but also the transition pathways between any two minima, as well as their corresponding energy barriers and transition state configurations. A global view of the free energy landscapes can then be visualized using either a disconnectivity graph or a network representation. Different forms of free energy functionals and boundary conditions can be readily implemented, thus allowing these tools to be utilised for a broad range of problems.
Functional differentiability in time-dependent quantum mechanics
Authors: Penz Markus , Ruggenthaler Michael
Published: April 2015

In this work, we investigate the functional differentiability of the time-dependent many-body wave function and of derived quantities with respect to time-dependent potentials. For properly chosen Banach spaces of potentials and wave functions, Fréchet differentiability is proven. From this follows an estimate for the difference of two solutions to the time-dependent Schrödinger equation that evolve under the influence of different potentials. Such results can be applied directly to the one-particle density and to bounded operators, and present a rigorous formulation of non-equilibrium linear-response theory where the usual Lehmann representation of the linear-response kernel is not valid. Further, the Fréchet differentiability of the wave function provides a new route towards proving basic properties of time-dependent density-functional theory.
Investigations of interface spin asymmetry and interfacial resistance in FexCo100−
x/Ag interface
Authors: Jung J. W. , Jin Z. , Shiokawa Y. , Sahashi M.
Published: April 2015

We investigated current-perpendicular-to-plane (CPP) magnetotransport parameters of FexCo100−x/Ag interfaces: interface specific resistance (ARF/N), extended interface resistance (AR*F/N), and spin scattering asymmetry (γ). We also investigated the dependence of interfacial parameters on the giant magnetoresistance effect with CPP geometry. For measuring these parameters, we prepared magnetic multilayers and pseudo spin valves (PSVs), combining the ferromagnetic (F) alloys Fe, Co, Fe50Co50, and Fe30Co70 with the nonmagnetic (N) metal Ag. In all cases, the largest ARF/N value was found to be ∼0.68 mΩ μm2 with an enhanced AR*F/N value of ∼1.9 mΩ μm2 for a (001)-oriented Fe/Ag interface, which suggests that spin-up and spin-down electrons on the Fermi surface have very different transmission probabilities. Such an interface can act as a spin filter through which only one type of electrons can pass.
Magnetic properties of Sm-Fe-N bulk magnets prepared from Sm2Fe17N3 melt-spun ribbons
Authors: Saito Tetsuji , Nishio-Hamane Daisuke
Published: April 2015

Sm-Fe-N bulk magnets were prepared from Sm2Fe17N3 melt-spun ribbon using the spark plasma sintering method. The bulk materials thus obtained had high densities of 90%–94%. The Sm-Fe-N bulk magnets produced at 723 K or lower retained the Sm2Fe17N3 phase of the melt-spun ribbon and exhibited a high coercivity. In contrast, the Sm2Fe17N3 phase decomposed during sintering at 773 K or higher, resulting in Sm-Fe-N bulk magnets with a lower coercivity. The Sm-Fe-N bulk magnets prepared from the Sm2Fe17N3 melt-spun ribbons sintered at 673 K exhibited an attractively high coercivity of 16.9 kOe with a remanence of 94.4 emu/g.
Emission properties of body-centered cubic elemental metal photocathodes
Authors: Li Tuo , Rickman Benjamin L. , Schroeder W. Andreas
Published: April 2015

A first principles analysis of photoemission is developed to explain the lower than expected rms transverse electron momentum measured using the solenoid scan technique for the body-centered cubic Group Vb (V, Nb, and Ta) and Group VIb (Cr, Mo, and W) metallic photocathodes. The density functional theory based analysis elucidates the fundamental role that the electronic band structure (and its dispersion) plays in determining the emission properties of solid-state photocathodes and includes evaluation of work function anisotropy using a thin-slab method.
Dynamic heterogeneity in the folding/unfolding transitions of FiP35
Authors: Mori Toshifumi , Saito Shinji
Published: April 2015

Molecular dynamics simulations have become an important tool in studying protein dynamics over the last few decades. Atomistic simulations on the order of micro- to milliseconds are becoming feasible and are used to study the state-of-the-art experiments in atomistic detail. Yet, analyzing the high-dimensional-long-temporal trajectory data is still a challenging task and sometimes leads to contradictory results depending on the analyses. To reveal the dynamic aspect of the trajectory, here we propose a simple approach which uses a time correlation function matrix and apply to the folding/unfolding trajectory of FiP35 WW domain [Shaw et al., Science 330, 341 (2010)]. The approach successfully characterizes the slowest mode corresponding to the folding/unfolding transitions and determines the free energy barrier indicating that FiP35 is not an incipient downhill folder. The transition dynamics analysis further reveals that the folding/unfolding transition is highly heterogeneous, e.g., the transition path time varies by ∼100 fold. We identify two misfolded states and show that the dynamic heterogeneity in the folding/unfolding transitions originates from the trajectory being trapped in the misfolded and half-folded intermediate states rather than the diffusion driven by a thermal noise. The current results help reconcile the conflicting interpretations of the folding mechanism and highlight the complexity in the folding dynamics. This further motivates the need to understand the transition dynamics beyond a simple free energy picture using simulations and single-molecule experiments.
Morphotropic phase boundary and magnetoelastic behaviour in ferromagnetic Tb1−xGdxFe2 system
Authors: Adil Murtaza , Yang Sen , Mi Meng , Zhou Chao , Wang Jieqiong , Zhang Rui , Liao Xiaoqi , Wang Yu , Ren Xiaobing , Song Xiaoping , Ren Yang
Published: April 2015

Morphotropic phase boundary (MPB), separating two ferroic phases of different crystal symmetries, has been studied extensively for its extraordinary enhancement of piezoelectricity in ferroelectrics. Based on the same mechanism, we have designed a magnetic MPB in the pseudobinary ferromagnetic system of Tb1−xGdxFe2 and the corresponding crystal structure, magnetic properties, and magnetostriction are explored. With the synchrotron x-ray diffractometry, the structure symmetry of TbFe2-rich compositions is detected to be rhombohedral (R) and that of GdFe2-rich compositions is tetragonal (T) below Tc. With the change of concentration, the value of magnetostriction of the samples changes monotonously, while the MPB composition Tb0.1Gd0.9Fe2, which corresponds to the coexistence of R and T phases, exhibits the maximum magnetization among all available compositions and superposition of magnetostriction behaviour of R and T phases. Our result of MPB phenomena in ferromagnets may provide an effective route to design functional magnetic materials with exotic properties.
Anisotropic magneto-optical hysteresis of permalloy slanted columnar thin films determined by vector magneto-optical generalized ellipsometry
Authors: Briley Chad , Schmidt Daniel , Hofmann Tino , Schubert Eva , Schubert Mathias
Published: April 2015

We present magneto-optical dielectric function tensor data of permalloy slanted columnar thin films obtained by vector magneto-optical generalized ellipsometry. Room-temperature hysteresis magnetization measurements were performed in transverse, longitudinal, and polar configurations, and at three different sample in plane azimuth orientations. We observe strongly anisotropic hysteresis behaviors, which depend on the nanocolumn and magnetizing field orientations. We present a model dielectric function approach by implementing vectorial magneto-optical magnetization hysteresis functions with major axes coincident with the major optical polarizability axes of the nanocolumns. Our approach provides excellent match with experimental data and reveals strongly anisotropic coercive field and ferromagnetic model parameters for the permalloy slanted columnar thin films. Ferromagnetic coupling is strongest parallel to the nanocolumn direction and substantially weaker perpendicular to the nanocolumns.
Tailoring functional properties of Ni nanoparticles-acrylic copolymer composites with different concentrations of magnetic filler
Authors: Kurlyandskaya G. V. , Safronov A. P. , Bhagat S. M. , Lofland S. E. , Beketov I. V. , Prieto L. Marcano
Published: April 2015

Magnetic composites with nickel nanoparticles synthesized by the method of the electrical explosion of wire were prepared with acrylic copolymer containing 95 wt. % of butylacrylate and 5 wt. % of methacrylic acid. Two series of composites were made with Ni content covering the range from 5 to 90 wt. % and differing in the degree of aggregation. In one series of composites, the aggregates were irregularly shaped globules with dimensions varying in 1–40 μm range. In the other, chain-like fragments were observed. As expected, the saturation magnetization value of the composites showed a linear dependence on concentration but the coercive field was slightly higher for the aggregated case for a given concentration. Microwave absorption studies of the composites showed both strong zero field absorption and ferromagnetic resonance (FMR). The FMR results were different for the two types of samples; however, each set can be explained by taking into account the distribution of local magnetic fields due to random positions of the particles.
Repetition frequency scaling of an all-polarization maintaining erbium-doped mode-locked fiber laser based on carbon nanotubes saturable absorber
Authors: Sotor J. , Sobon G. , Jagiello J. , Lipinska L. , Abramski K. M.
Published: April 2015

We demonstrate an all-polarization maintaining (PM), mode-locked erbium (Er)-doped fiber laser based on a carbon nanotubes (CNT) saturable absorber (SA). The laser resonator was maximally simplified by using only one passive hybrid component and a pair of fiber connectors with deposited CNTs. The repetition frequency (Frep) of such a cost-effective and self-starting mode-locked laser was scaled from 54.3 MHz to 358.6 MHz. The highest Frep was obtained when the total cavity length was shortened to 57 cm. The laser allows ultrashort pulse generation with the duration ranging from 240 fs to 550 fs. Because the laser components were based on PM fibers the laser was immune to the external perturbations and generated laniary polarized light with the degree of polarization (DOP) of 98.7%.
Influence of Cr on the nanoclusters formation and superferromagnetic behavior of Fe-Cr-Nb-B glassy alloys
Authors: Chiriac H. , Whitmore L. , Grigoras M. , Ababei G. , Stoian G. , Lupu N.
Published: April 2015

High resolution imaging and electron diffraction confirm that in the as-quenched state the structure of Fe79.7−xCrxNb0.3B20 (x = 11–13 at. %) melt-spun ribbons is completely amorphous, independent of the Cr content. Energy-dispersive X-ray spectroscopy mapping emphasizes clearly the presence of Fe and Cr clusters varying from approximately 1 to 2–3 nm in size with the increase of Cr content from 11 to 13 at. %. The Fe and Cr atoms segregate the atomic scale to form nanometer sized clusters, influencing strongly the macroscopic magnetic behavior. The Curie temperature of the system, TCsystem, confirmed by the magnetic susceptibility versus temperature measurements, gives the strength of the magnetic interactions between clusters. The inter-cluster interactions are much stronger for lower contents of Cr, the microstructure is less uniform, and TCsystem increases from 290 K for 13 at. % Cr to 330 K for 11.5 at. % Cr. The whole system transforms to a ferromagnetic state through interactions between the clusters. Zero-field cooling and field cooling curves confirm the cluster behavior with a blocking temperature, Tb, of about 250 K. Above Tb, the ribbons behave as a superferromagnetic system, whilst below the blocking temperature a classical ferromagnetic behavior is observed.
Synchronization and optimization of semiconductor ring lasers with self-feedback
Authors: Xue Ping-Ping , Zhang Jian-Zhong , Yang Ling-Zhen
Published: April 2015

This paper deals with the problem of synchronization and optimization of semiconductor ring lasers. When the frequency mismatch is −20 GHz and the injection coefficient is greater than 2.5, the semiconductor ring lasers in two different configurations (open and closed loops) can all achieve good synchronizations with cross correlation coefficients above 0.95. The robustness of two configurations to frequency detuning are discussed and the results show the synchronization quality of open loop strategy are superior to that of closed loop. Effects of internal parameter mismatches on synchronization quality are also studied. Through modulating internal parameters of semiconductor ring lasers the synchronization quality of two configurations can be optimized. The correlation coefficient of closed loop strategy increases from 0.97 to 0.99, (0.95 to 0.96 about open loop).
Analysis of the scintillation mechanism in a pressurized 4He fast neutron detector using pulse shape fitting
Authors: Kelley R.P. , Murer D. , Ray H. , Jordan K.A.
Published: April 2015

An empirical investigation of the scintillation mechanism in a pressurized 4He gas fast neutron detector was conducted using pulse shape fitting. Scintillation signals from neutron interactions were measured and averaged to produce a single generic neutron pulse shape from both a 252Cf spontaneous fission source and a (d,d) neutron generator. An expression for light output over time was then developed by treating the decay of helium excited states in the same manner as the decay of radioactive isotopes. This pulse shape expression was fitted to the measured neutron pulse shape using a least-squares optimization algorithm, allowing an empirical analysis of the mechanism of scintillation inside the 4He detector. A further understanding of this mechanism in the 4He detector will advance the use of this system as a neutron spectrometer. For 252Cf neutrons, the triplet and singlet time constants were found to be 970 ns and 686 ns, respectively. For neutrons from the (d,d) generator, the time constants were found to be 884 ns and 636 ns. Differences were noted in the magnitude of these parameters compared to previously published data, however the general relationships were noted to be the same and checked with expected trends from theory. Of the excited helium states produced from a 252Cf neutron interaction, 76% were found to be born as triplet states, similar to the result from the neutron generator of 71%. The two sources yielded similar pulse shapes despite having very different neutron energy spectra, validating the robustness of the fits across various neutron energies.
Band gap engineering of Si-Ge alloys for mid-temperature thermoelectric applications
Authors: Pulikkotil J. J. , Auluck S.
Published: April 2015

The viability of Si-Ge alloys in thermoelectric applications lies in its high figure-of-merit, non-toxicity and earth-abundance. However, what restricts its wider acceptance is its operation temperature (above 1000 K) which is primarily due to its electronic band gap. By means of density functional theory calculations, we propose that iso-electronic Sn substitutions in Si-Ge can not only lower its operation to mid-temperature range but also deliver a high thermoelectric performance. While calculations find a near invariance in the magnitude of thermopower, empirical models indicate that the materials thermal conductivity would also reduce, thereby substantiating that Si-Ge-Sn alloys are promising mid-temperature thermoelectrics.
Window-assisted nanosphere lithography for vacuum micro-nano-electronics
Authors: Li Nannan , Pang Shucai , Yan Fei , Chen Lei , Jin Dazhi , Xiang Wei , Zhang De , Zeng Baoqing
Published: April 2015

Development of vacuum micro-nano-electronics is quite important for combining the advantages of vacuum tubes and solid-state devices but limited by the prevailing fabricating techniques which are expensive, time consuming and low-throughput. In this work, window-assisted nanosphere lithography (NSL) technique was proposed and enabled the low-cost and high-efficiency fabrication of nanostructures for vacuum micro-nano-electronic devices, thus allowing potential applications in many areas. As a demonstration, we fabricated high-density field emitter arrays which can be used as cold cathodes in vacuum micro-nano-electronic devices by using the window-assisted NSL technique. The details of the fabricating process have been investigated. This work provided a new and feasible idea for fabricating nanostructure arrays for vacuum micro-nano-electronic devices, which would spawn the development of vacuum micro-nano-electronics.
South Dakota begins to reap benefits of underground lab
Authors: Feder Toni
Published: April 2015

The boon to the state’s education and economy will be amplified if the Long-Baseline Neutrino Facility is realized.
President Obama’s FY 2016 R&D budget would surpass spending caps
Authors: Kramer David
Published: April 2015

The Department of Energy and NSF would get healthy increases while basic research programs at the Department of Defense and NASA would see reductions.
Butterflies that trick ants with sound
Authors: Barbero Francesca , Casacci Luca Pietro
Published: April 2015

Larvae of parasitic Maculinea butterflies use acoustic mimicry to induce host ants to adopt and care for them.
Using growth and body composition to determine weight at maturity in Nellore cattle
Authors: Marcondes Marcos Inacio , Tedeschi Luís Orlindo , Filho Sebastião de Campos Valadares , Costa e Silva Luiz Fernando , Lopes da Silva Alex
Published: April 2015

The aim of the present study was to estimate the relationships among water, crude protein (CP), ether extract (EE) and ash in the empty bodyweight (EBW), and the soft tissue and bone and, moreover, to determine an objective method to define weight at maturity in Nellore cattle. A dataset containing carcass and body compositions of 249 animals from 11 experiments was developed. There were 63 bulls, 105 steers, and 81 heifers where all animals were purebred Nellore, aged between zero and 24 months. The contents of water, CP and ash in the EBW were predicted by non-linear regressions, whereas an exponential model was used to predict EE. In addition, the content of CP was predicted on a fat-free dry matter (FFDM) basis, and maturity was defined as the point when no significant accretion of CP in the FFDM was observed. The soft tissue water (STW) was regressed on logistic Gompertz functions, and segmented regression models, whereas the analysis of bone chemical composition in the EBW was conducted using an exponential model. The gender effect was not significant (P > 0.05) for EBW and EE; therefore, this effect was not included in the analysis of FFDM. The exponential model suggests that Nellore cattle reached maturity at ~445 kg and the segmented regression model suggested that maturity was reached at 429 kg. A significant relationship between the concentration of STW and soft tissue EE (STEE) was observed (STEE = 0.920 – 1.147 × STW; r2 = 0.96, mean square error = 1.01), but the soft tissue was not a good predictor of maturity, because it is dependent on the diet. Analysis of bone chemical composition showed that EE, water and ash become constant between 400 and 500 kg of EBW, and that CP in bones was constant at 19.1% of EBW. These data also suggested that bone composition could be a good predictor of maturity; however, with the high variability in our dataset, it was not possible to determine an EBW at which these components became constant with a reliable precision. We concluded that Nellore cattle reach maturity at ~437 kg of EBW and that CP in the FFDM and CP, water and ash in bones are good predictors of maturity, whereas soft tissue composition is not a useful predictor of maturity.
Response of two broiler strains to four feeding regimens under hot climate
Authors: Attia Youssef A. , Al-Tahawy Waleed S. , de Oliveira Maria C. , Al-Harthi Mohammed A. , El-Din Abd Alrazk. E. Tag , Hassan Mohamed I.
Published: April 2015

In total, 392 male broilers were randomly distributed in a factorial arrangement of 2 × 4, with two commercial broiler strains (Arbor Acres (AA) and Hubbard (Hub)) and four (NRC, Degussa, CVB, and strain guides) different feeding regimens (FR), totaling eight treatments and seven replicates, with seven broilers in each one. The following parameters were evaluated: bodyweight gain (BWG), feed intake (FI), feed conversion ratio (FCR), carcass yield, meat quality, nutrient intake, and its correlation with BWG. Interaction strain type × FR was significant for BWG, FI, and FCR, with the AA broilers showing higher BWG and FI and lower FCR than the Hub broilers. There was no difference in BWG, FI, and FCR of the AA broilers regardless of FR they were on, but the Hub broilers had lower BWG when they were fed according to the Degussa and CVB regimens; BWG and FCR were negatively affected. During the starter phase, BWG of the AA broilers was significantly correlated with feed, metabolisable energy (ME), lysine, and sulfur amino acids (SAA) intake. However, BWG was correlated with feed and ME intake and feed intake from 1 to 31 and from 1 to 42 days of age, respectively. In the Hub chicks, ME and crude protein intake and lysine and SAA intake were inversely correlated with BWG from 1 to 31 days and from 1 to 42 days of age, respectively. There was no significant effect of FR on dressed carcass weight or relative gizzard, pancreas, and liver weights and on intestinal weight; however, abdominal fat and spleen differed significantly with FR. Strain type significantly affected the relative weight of the intestines. There was no significant effect of FR and/or strain type on meat moisture, crude protein, lipid and ash content, or pH, colour, meat juiciness and tenderness (meat softness). In conclusion, AA strain of broiler performed better than the Hub strain under the different FR in all the evaluated production phases, but neither FR nor strain type affected carcass characteristics.
Effect of timing and height of defoliation on the grain yield of barley, wheat, oats and canola in Western Australia
Authors: Seymour Mark , England Jonathan H. , Malik Raj , Rogers David , Sutherland Andrew , Randell Allen
Published: April 2015

Winter cropping in Western Australia (WA) is dominated by spring-type cereals and canola (Brassica napus L.) with no vernalisation requirement that are sown in late autumn (late April and May). With limited earlier sowing opportunities for later maturing winter-type crops in early autumn, farmers aiming to obtain some benefit from the grazing of crops (i.e. dual-purpose) must consider the grazing potential of spring types sown in late autumn. The aim of this study was to develop grazing guidelines for spring-type crops in WA that will limit the potential for grain yield losses. In order to determine the recovery response of spring-type crops to grazing intensity and timing, 59 time-of-cutting × height-of-cutting experiments were conducted throughout the south-western region of WA in 2012. Experiments were conducted on spring types of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), canola and oats (Avena sativa L.). Multi-site analysis showed that treatments simulating high-intensity ‘crash’ grazing to ground level or to a height of 5 cm reduced grain yield unless conducted early in vegetative growth before reproductive stages. Treatments simulating ‘clip’ grazing by removing only the top 5–10 cm of crop foliage reduced grain yield to a lesser extent than crash grazing, and in several instances could extend the safe cutting period past hollow stem (Zadoks growth stage 30) and/or the end of July for cereals, or past mid-July for spring canola, provided the developing reproductive parts of all crops were not damaged. On average, the amounts of biomass removed by clip grazing without yield penalty were 0.4, 0.3, 0.5 and 0.3 t ha–1 for barley, wheat, oats and canola and were similar to those removed by earlier, safe crash grazing. These represent significant amounts of forage and suggest that clip grazing of spring-type crops may be an approach suited to WA cropping and grazing systems.
Integrating dual-purpose wheat and canola into high-rainfall livestock systems in south-eastern Australia. 2. Pasture and livestock production
Authors: Dove H. , Kirkegaard J. A. , Kelman W. M. , Sprague S. J. , McDonald S. E. , Graham J. M.
Published: April 2015

In south-eastern Australia, low winter temperatures often reduce pasture growth and thus winter herbage supply relative to livestock requirements. Grazing of vegetative grain crops in winter is one strategy that might overcome this feed gap. In a study with young sheep over two seasons near Canberra, ACT, we compared pasture-only grazing with three separate crop–livestock systems in which the sheep grazed long-season wheat, winter canola or a combination of these, for intervals over the period May–August. We measured forage biomass, sheep grazing days (SGD) and liveweight accumulated per ha. Crop-grazing treatments resulted in much more winter forage for grazing sheep (t DM ha–1): in 2010, one crop 2.5–3.0, two crops 3.5 v. pasture only 1; in 2011, one crop 2, two crops 3 v. pasture only 1.4. In the first season, grazing one crop resulted in ~2000 extra SGD ha–1 and the accumulation of more liveweight per ha than in the pasture-only treatment; grazing of two crops resulted in >3500 extra SGD ha–1. Equivalent values in the second, drier season were: one crop, ~1000 extra SGD ha–1; two crops, 2600 extra SGD ha–1. Spelling of pastures during crop grazing led to extra pasture growth, such that in each of the two seasons, 40% of the total benefit in extra SGD per ha came from the extra pasture.
The results indicate that, like grazed wheat, grazed canola can provide valuable winter forage, especially when used together with wheat. The data also provide the first quantification of the effect of crop grazing on pasture spelling and subsequent pasture supply, and suggest value in the incorporation of grazing wheat and canola into grazing systems in the high-rainfall zone.
Forage and grain yield of grazed or defoliated spring and winter cereals in a winter-dominant, low-rainfall environment
Authors: Frischke Alison. J. , Hunt James R. , McMillan Dannielle K. , Browne Claire J.
Published: April 2015

In the Mallee region of north-western Victoria, Australia, there is very little grazing of crops that are intended for grain production. The success of dual-purpose crops in other regions in south-eastern Australia with higher and more evenly distributed rainfall has driven interest in assessing the performance of dual-purpose cereals in the region. Five experiments were established in five consecutive years (2009–13) in the southern Mallee to measure the forage production and grain yield and quality response in wheat and barley to grazing by sheep or mechanical defoliation. The first three experiments focused on spring cultivars sown from late April to June, and the last two on winter cultivars planted from late February to early March. Cereal crops provided early and nutritious feed for livestock, with earlier sowing increasing the amount of dry matter available for winter grazing, and barley consistently produced more dry matter at the time of grazing or defoliation than wheat. However, the grain-production response of cereals to grazing or defoliation was variable and unpredictable. Effects on yield varied from –0.7 to +0.6 t/ha, with most site × year × cultivar combinations neutral (23) or negative (14), and few positive (2). Changes in grain protein were generally consistent with yield dilution effects. Defoliation increased the percentage of screenings (grains passing a 2-mm sieve) in three of five experiments. Given the risk of reduced grain yield and quality found in this study, and the importance of grain income in determining farm profitability in the region, it is unlikely that dual-purpose use of current cereal cultivars will become widespread under existing grazing management guidelines for dual-purpose crops (i.e. that cereal crops can be safely grazed once anchored, until Zadoks growth stage Z30, without grain yield penalty). It was demonstrated that early-sown winter wheat cultivars could produce more dry matter for grazing (0.4–0.5 t/ha) than later sown spring wheat and barley cultivars popular in the region (0.03–0.21 t/ha), and development of regionally adapted winter cultivars may facilitate adoption of dual-purpose cereals on mixed farms.
Pharmaceuticals and personal care products alter growth and function in lentic biofilms
Authors: Shaw Lawton , Phung Chuyen , Grace Michael
Published: April 2015

Environmental context Pharmaceuticals and personal care products are routinely found in waters discharged from treatment plants and in surrounding aquatic ecosystems. Despite the widespread occurrence of these biologically active agents, there is limited understanding of their potential effects on key ecosystem processes such as primary production, ecosystem respiration and algal growth. This paper examines the effects of five common pharmaceuticals on the rates of these fundamental processes. Abstract Pharmaceutical diffusing substrates were used to study in situ responses of aquatic biofilms in an urbanised lentic ecosystem to five pharmaceutical and personal care products (PPCPs; caffeine, cimetidine, ciprofloxacin, diphenhydramine and metformin). The pharmaceutical diffusing substrates consisted of porous biofilm substrates placed atop a mass of agar amended with 2.5mM of the PPCP compound of interest. Over 21 days, biofilms growing on the substrata were exposed to slow diffusion of the PPCP through the agar and porous substrate. Algal biomass was suppressed by exposure to diphenhydramine (–81%) and ciprofloxacin (–50%). Gross primary production was completely suppressed by diphenhydramine exposure but stimulated by caffeine (+39%) and cimetidine (+46%). For heterotroph biofilms, community respiration was suppressed by exposure to diphenhydramine (–24%). To characterise PPCP exposure, rates of diffusion from the pharmaceutical diffusing substrates were measured at 10, 20 and 30°C. Diffusion was Fickian for all compounds and all temperatures. Diffusion coefficients, D, were in the range 1.5×10–10 to 1.1×10–9m2s–1. From diffusion data, average release rates over 21 days were typically 30–50ngmin–1cm–2 at 20°C. The results show that PPCPs can dramatically affect rates of key ecological processes, and the relationship between release rate and ambient concentration of PPCPs is discussed.
Sea-surface temperature used to predict the relative density of giant Pacific octopuses (Enteroctopus dofleini) in intertidal habitats of Prince William Sound, Alaska
Authors: Scheel D.
Published: April 2015

Productivity linked to upwelling strength is an important environmental factor affecting the production and dynamics of octopus populations. This often takes the form of a negative relationship between octopus abundance and sea-surface temperatures (SST). Enteroctopus dofleini (giant Pacific octopuses) is caught as by-catch in several fisheries, but management for octopuses is data-poor. Visual surveys (in Prince William Sound (PWS) and Puget Sound) showed significant negative correlations of octopus counts with winter SST over the previous 30 months in the waters of eastern Gulf of Alaska, as expected on the basis of life-history parameters. In PWS, local octopus densities varied more than six-fold during the study, and correlations with SST accounted for 48–61% of the variance in counts. Octopus by-catch datasets were not similarly significantly correlated with SST. The negative correlation with SST suggests that octopus populations are influenced by factors regulating marine productivity during larval stages of life history far from the site of recruitment to benthic habitats. Targeted visual surveys for E. dofleini may be more predictable than by-catch statistics, and may be better estimators of variation in octopus abundance.
Eluding catastrophic shifts
Authors: Villa Martín Paula , Bonachela Juan A. , Levin Simon A. , Muñoz Miguel A.
Published: April 2015

Significance

Catastrophic shifts such as desertification processes, massive extinctions, or stock market collapses are ubiquitous threats in nature and society. In these events, there is a shift from one steady state to a radically different one, from which recovery is exceedingly difficult. Thus, there is a huge interest in predicting and eventually preventing catastrophic shifts. Here we explore the influence of key mechanisms such as demographic fluctuations, heterogeneity, and diffusion, which appear generically in real circumstances. The mechanisms we study could ideally be exploited to smooth abrupt shifts and to make transitions progressive and easier to revert. Thus, our findings could be of potential importance for ecosystem management and biodiversity conservation.
α-Synuclein, a chemoattractant, directs microglial migration via H2O2-dependent Lyn phosphorylation
Authors: Wang Shijun , Chu Chun-Hsien , Stewart Tessandra , Ginghina Carmen , Wang Yifei , Nie Hui , Guo Mingri , Wilson Belinda , Hong Jau-Shyong , Zhang Jing
Published: April 2015

Significance

α-Synuclein (α-syn) aggregates released from neurons activate microglia, leading to chronic neuroinflammation that causes damage to neurons in brains with synucleinopathies, such as Parkinson’s disease (PD). However, little is known about the mechanism by which α-syn affects microglial activity, especially motility, and why microglia migrate toward the injured neurons and preferentially accumulate along with α-syn aggregates in the affected areas, e.g., in the substantia nigra of PD brains. Here we show that neuron-derived α-syn aggregates are chemoattractants that direct microglial migration by acting on NADPH oxidase and several specific downstream proteins. Blocking the targets involved in α-syn–mediated microglial directional migration may represent a therapeutic strategy to protect against progressive neuronal loss in PD and related synucleinopathies.
Sphingomyelin distribution in lipid rafts of artificial monolayer membranes visualized by Raman microscopy
Authors: Ando Jun , Kinoshita Masanao , Cui Jin , Yamakoshi Hiroyuki , Dodo Kosuke , Fujita Katsumasa , Murata Michio , Sodeoka Mikiko
Published: April 2015

Significance

Phase separation in lipid rafts has been observed with fluorescently labeled lipids, but they are often excluded from the ordered domain because of the steric effect of the bulky fluorophore on lipid packing, making it difficult to analyze the interior of the raft domain. Here, we synthesized an analog of sphingomyelin tagged with a small Raman active diyne moiety, which provides high chemical selectivity without affecting the membrane properties. Raman microscopy successfully visualized, at single lipid-layer sensitivity, a heterogeneous spatial distribution of this probe within raft-like ordered domains, which was different from the generally accepted raft model. This approach provides both chemical selectivity and quantitative imaging capability and is useful for functional studies of lipid rafts.
Alternative splicing of the androgen receptor in polycystic ovary syndrome
Authors: Wang Fangfang , Pan Jiexue , Liu Ye , Meng Qing , Lv Pingping , Qu Fan , Ding Guo-Lian , Klausen Christian , Leung Peter C. K. , Chan Hsiao Chang , Yao Weimiao , Zhou Cai-Yun , Shi Biwei , Zhang Junyu , Sheng Jianzhong , Huang Hefeng
Published: April 2015

Significance

Excess androgens and abnormal follicle development, largely due to ovarian granulosa cell (GC) dysfunction, characterize polycystic ovary syndrome (PCOS), a common endocrinopathy of women predisposing to infertility. Thus, it is important to understand GC dysfunction. The androgen receptor (AR) is widely believed to be an essential regulator of GC biology. High expression of AR in GCs is primarily considered to associate with PCOS. However, we show that AR alternative splice variants in GCs disturb androgen metabolism and follicle growth, leading to PCOS because of impaired transcription factor function. These data considerably change our understanding of the role of AR in the etiology of PCOS, and inform the development of clinical diagnostic and classification tests as well as novel therapeutic interventions.
Coding of envelopes by correlated but not single-neuron activity requires neural variability
Authors: Metzen Michael G. , Jamali Mohsen , Carriot Jérome , Ávila-Ǻkerberg Oscar , Cullen Kathleen E. , Chacron Maurice J.
Published: April 2015

Significance

We provide the first experimental evidence (to our knowledge) that correlated population activity can serve as an extra channel to encode second-order features of sensory input in both the electrosensory and vestibular systems. Through further experiments and mathematical modeling, we show that such coding not only requires but is also optimally tuned to a nonzero level of variability. Finally, we demonstrate that only physiologically realistic decoding circuits that explicitly include the contributions of pairwise neural activity can reliably be used to reconstruct the envelope. Our results reveal new functional roles for correlated activity and neural variability that are generally applicable across systems and species.
Plethora of transitions during breakup of liquid filaments
Authors: Castrejón-Pita José Rafael , Castrejón-Pita Alfonso Arturo , Thete Sumeet Suresh , Sambath Krishnaraj , Hutchings Ian M. , Hinch John , Lister John R. , Basaran Osman A.
Published: April 2015

Significance

Fluid flows, governed by nonlinear equations, permit formation of singularities. Often, singularities are artifacts of neglecting physical effects. However, free-surface flows exhibit observable singularities including filament pinch-off. As filaments thin, slightly (highly) viscous filaments are expected from theory to transition from an inertial (viscous) regime where viscosity (density) is negligible to an inertial–viscous regime where viscous and inertial effects are important. Previous works show this transition either does not occur or occurs for filament radii well below theoretical predictions. We demonstrate that thinning filaments unexpectedly pass through a number of intermediate transient regimes, thereby delaying onset of the final regime. The findings raise the question if similar dynamical transitions arise in problems that are not necessarily hydrodynamic in nature.
Rate and mechanism of the photoreduction of birnessite (MnO
2
) nanosheets
Authors: Marafatto Francesco Femi , Strader Matthew L. , Gonzalez-Holguera Julia , Schwartzberg Adam , Gilbert Benjamin , Peña Jasquelin
Published: April 2015

Significance

The photoreductive dissolution of Mn oxides governs the biogeochemical cycle of Mn and the fate of organic and inorganic species associated with Mn oxides in the euphotic zones of marine and freshwater systems. Mn oxide minerals also have garnered interest as water oxidation catalysts inspired by the Mn
4
CaO
4
cluster of photosystem II. However, the mechanism of water oxidation by MnO
2
and the rate limiting steps for this reaction are unknown. In this study, we couple flow-through experiments and ultrafast pump–probe optical and X-ray absorption spectroscopy to develop a photoreduction model that includes the mechanism and timescales for the initial electron transfer steps in the oxidation of water by MnO
2
.