bluuebunny/crossref_metadata_2025 huggingface dataset:
A model for wet aggregation of ash particles in volcanic plumes and clouds: 2. Model application
Authors: Folch A. , Costa A. , Durant A. , Macedonio G.
Published: August 2010

The occurrence of particle aggregation has a dramatic effect on the transport and sedimentation of volcanic ash. The aggregation process is complex and can occur under different conditions and in multiple regions of the plume and in the ash cloud. In the companion paper, Costa et al. develop an aggregation model based on a fractal relationship to describe the rate particles are incorporated into ash aggregates. The model includes the effects of both magmatic and atmospheric water present in the volcanic cloud and demonstrates that the rate of aggregation depends on the characteristics of the initial particle size distribution. The aggregation model includes two parameters, the fractal exponent Df, which describes the efficiency of the aggregation process, and the aggregate settling velocity correction factor ψe, which influences the distance at which distal mass deposition maxima form. Both parameters are adjusted using features of the observed deposits. Here this aggregation model is implemented in the FALL3D volcanic ash transport model and applied to the 18 May 1980 Mount St. Helens and the 17–18 September 1992 Crater Peak eruptions. For both eruptions, the optimized values for Df (2.96–3.00) and ψe (0.27–0.33) indicate that the ash aggregates had a bulk density of 700–800 kg m−3. The model provides a higher degree of agreement than previous fully empirical aggregation models and successfully reproduces the depositional characteristics of the deposits investigated over a large range of scales, including the position and thickness of the secondary maxima.
Deconstructing the precipitation susceptibility construct: Improving methodology for aerosol‐cloud precipitation studies
Authors: Sorooshian Armin , Feingold Graham , Lebsock Matthew D. , Jiang Hongli , Stephens Graeme L.
Published: August 2010

It is generally thought that an increase in aerosol particles suppresses precipitation in warm clouds. The nature and magnitude of this effect are highly uncertain owing to numerous microphysical and macrophysical processes that influence clouds over a wide range of spatial and temporal scales. This work addresses the need to improve the evidence for and quantification of aerosol effects on precipitation by using observational data. Previous work introduced the concept of precipitation susceptibility as a metric for changes in precipitation that result from aerosol perturbations. Motivated by the difficulty in obtaining statistically significant aerosol measurements in the vicinity of clouds, this study explores breaking up the precipitation susceptibility construct into separate components: an aerosol‐cloud interaction component and a cloud‐precipitation component. These are used to quantify precipitation susceptibility, while also accounting for meteorological factors that could obfuscate the response of clouds to aerosol perturbations. The utility of this technique is demonstrated using a diverse set of tools, including data from NASA's A‐Train constellation of satellites, aircraft measurements, and models of various complexities. Employing this method results in increased confidence in causal relationships between aerosol perturbations and precipitation.
Field evidence of pore pressure diffusion in clayey soils prone to landsliding
Authors: Berti Matteo , Simoni Alessandro
Published: August 2010

The hydrologic behavior of shallow weathered soils commonly determines the propensity for slope failure. Here we use laboratory data and field data collected by an automated monitoring system to assess the character of pore water pressure responses in a natural clay slope subject to intermittent rainfall. Although we did not measure pore pressure distributions that triggered slope failure, we obtained three years of field data that provided reliable and largely reproducible documentation of transient pore pressure responses. At depths of tens of centimeters to a few meters below the ground surface, moisture and pressure sensors recorded relatively fast, transient responses to precipitation. The speeds of pore pressure pulses advancing downward in the saturated zone were much larger than those of advective fronts driven by gravity, and the amplitudes of the pulses attenuated with depth. Statistical assessment of 129 pressure head responses demonstrates that this behavior is consistent with predictions of a linear, one‐dimensional pore pressure diffusion model. However, the model best simulates measurements if diffusivity is treated as a calibration parameter and if initial moisture conditions match model assumptions. For regional assessment of slope stability, the predictive accuracy of the linear‐diffusion model is limited by inherent uncertainties in defining the initial conditions and in assigning the values of hydraulic parameters.
Forest recovery and river discharge at the regional scale of Guangdong Province, China
Authors: Zhou Guoyi , Wei Xiaohua , Luo Yan , Zhang Mingfang , Li Yuelin , Qiao Yuna , Liu Haigui , Wang Chunlin
Published: August 2010

Information on how large‐scale forest changes affect water resources is important in China as country‐wide reforestation programs are being implemented and concerns have arisen over possible water reduction. In this study, water budget analysis and statistical methods were used to assess the effects of significant forest recovery on river discharge at Guangdong Province based on 50 years of data. We used realized water yield (RWY) as a balance term between the outflows from and inflows to the province to represent the river discharge produced solely in Guangdong Province. The relationship between forest recovery and RWY was inferred after quantitatively examining other contributing variables including precipitation, potential evapotranspiration, development of impervious areas, human water consumption, and reservoir constructions. We applied time series analysis to test the statistical relationship between forest recovery and RWYs at annual, wet season, and dry season intervals. Both approaches showed that large‐scale forest recovery did not cause significant water reduction over the past 50 years. This finding is contrary to the widely held perception of the trade‐off relationship between carbon (reforestation) and water. There were no significant trends in precipitation or in RWY annually and in the wet season, but there was a significant increase of RWY in the dry season over the past 50 years. It is estimated that forest recovery may play a positive role in redistributing water from the wet season to the dry season and, consequently, in increasing water yield in the dry season. The implication of those research findings for future reforestation programs and water resource protection is also discussed.
New Imprint for AGU Books
Authors: Aldred Maxine
Published: August 2010

AGU is reinvigorating its books program as geo press. The new imprint for AGU books brings renewed enthusiasm to that portion of the Union's publishing program. For more than 85 years, AGU books have provided access to the work of scientists worldwide. The new imprint will lead the way for AGU to publish increasing numbers of single‐ and multiple‐author scientific works.
Routine determination of the plasmapause based on COSMIC GPS total electron content observations of the midlatitude trough
Authors: Pedatella N. M. , Larson K. M.
Published: August 2010

Observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) GPS precise orbit determination (POD) antennae are used to create a database of vertical total electron content (VTEC) measurements between roughly 800 and 20,200 km. Owing to the correlation between the midlatitude trough and the plasmapause, the COSMIC GPS VTEC observations are used to determine the plasmapause location throughout 2008. The COSMIC observations of the plasmapause during 2008 are used to illustrate the variations with local time and geomagnetic activity as well as to reveal periodic behavior of the plasmapause. The plasmapause variation with geomagnetic activity obtained by the COSMIC observations is found to be consistent with previous results based on different observation methods. The similarity to prior results demonstrates the effectiveness of using the COSMIC POD observations for determining the plasmapause. The COSMIC observations further reveal that the plasmapause exhibits significant variability and is, on average, primarily invariant in local time. The plasmapause is also found to oscillate at periods of 9 and 13.5 days during 2008 in connection with recurrent geomagnetic activity due to high‐speed solar wind streams. This is the first time that multiday oscillations have been observed in the plasmapause. The presence of a periodic modulation of the plasmapause further demonstrates the importance of periodic high‐speed streams in the Earth's upper atmosphere and inner magnetosphere during the current solar minimum.
Plasma conditions and the structure of the Jovian ring
Authors: Horányi Mihály , Juhász Antal
Published: August 2010

We explore the dynamics of small charged dust particles in Jupiter's innermost magnetosphere and show that the systematic charge variation of the grains results in surprisingly short lifetimes. Assuming a constant production of small dust particles via continual micrometeoroid bombardment of the larger parent bodies of the main ring, this model reproduces remote sensing observations of the ring/halo region at Jupiter made by Voyager, Galileo, Cassini, and New Horizons spacecraft and observations from the ground by the Keck telescope during ring plane crossings. We use this model to make predictions for the dust impact rates for the JUNO mission, which is expected to traverse this region multiple times starting in 2016.
Comparative study of ecohydrological streamflow probability distributions
Authors: Ceola Serena , Botter Gianluca , Bertuzzo Enrico , Porporato Amilcare , Rodriguez‐Iturbe Ignacio , Rinaldo Andrea
Published: August 2010

We run a comparative study of ecohydrological models of streamflow probability distributions (pdfs), p(Q), derived by Botter et al. (2007a, 2009), against field data gathered in different hydrological contexts. Streamflows measured in several catchments across various climatic regions of northeastern Italy and the United States are employed. The relevance of the work stems from the implied analytical predictive ability of hydrologic variability, whose role on stream and riparian ecological processes and large‐scale management schemes is fundamental. The tools employed are analytical models of p(Q) (and of the related flow duration curve, D(Q)) derived by coupling suitable storage‐discharge relations with a stochastic description of streamflow production through soil moisture dynamics, and are expressed as a function of few macroscopic rainfall, soil, vegetation and geomorphological parameters. In this work we compare the performances of a recent version of the model (which includes the effects of nonlinear subsurface storage‐discharge relations) to those provided by the linear version through the application of the models to 13 test catchments belonging to various climatic and geomorphic contexts. A general agreement between predicted and observed daily streamflows pdfs is shown, though differences emerge between the linear and the nonlinear approaches. In particular, by including the effects of a nonlinear storage‐discharge relation the model accuracy is shown to increase with respect to the linear scheme in most examined cases. We show that this is not simply attributable to the added parameter but corresponds to a proper likelihood increase. The nonlinear model is shown to exhibit three basic forms for p(Q) (monotonically decreasing with an atom of probability in Q = 0, bell‐shaped with the mode close to zero, bell‐shaped with the mode close to the mean), corresponding to different hydrologic regimes which are clearly detectable in field data. Inferences on the nonlinear character of the relation between subsurface storage and discharge from observed p(Q) are finally drawn.
The psycho gene
Authors: Hunter Philip
Published: August 2010

The notion of ‘the criminal gene’ is now dead and buried. Yet there is growing evidence that some psychopathic behaviour is indeed grounded in our genes and has an evolutionary origin
The lymphoid chemokine CCL21 triggers LFA‐1 adhesive properties on human dendritic cells
Authors: Eich Christina , de Vries I Jolanda M , Linssen Peter CM , de Boer Annemiek , Boezeman Jan B , Figdor Carl G , Cambi Alessandra
Published: August 2010

Dendritic cells (DCs) are the most potent APCs, involved in the induction of immunity and tolerance. Recently we showed that during differentiation of human DCs from monocyte precursors, Lymphocyte function‐associated antigen‐1 (LFA‐1)‐binding capacity is lost, although integrin expression levels were maintained constant, suggesting a different regulation mechanism of this integrin on different cell types. However, the exact role of LFA‐1 in DC adhesion and migration remains obscure. Chemokines are potent regulators of integrin function, influencing migratory and adhesive properties of leukocytes. Here, we show that upon vaccination of cancer patients with human DCs, cells that have migrated in vivo into the lymph nodes upregulated the active form of LFA‐1. We further show that exposure of human DCs to the lymphoid chemokine CCL21 specifically restores the high‐affinity form of LFA‐1 and induces binding to its ligand ICAM‐1 under low shear stress. Our data indicate that on DCs LFA‐1 may function as an inducible anchor during lymphatic transmigration or within the lymph nodes. A thorough understanding of the adhesive events during the DC life cycle will help to improve the outcome of DC‐based antitumor clinical trials.
The role of vicinal tyrosine residues in the function of Haemophilus influenzae ferric-binding protein A
Authors: Khambati Husain K. , Moraes Trevor F. , Singh Jagroop , Shouldice Stephen R. , Yu Rong-hua , Schryvers Anthony B.
Published: August 2010

The periplasmic FbpA (ferric-binding protein A) from Haemophilus influenzae plays a critical role in acquiring iron from host transferrin, shuttling iron from the outer-membrane receptor complex to the inner-membrane transport complex responsible for transporting iron into the cytoplasm. In the present study, we report on the properties of a series of site-directed mutants of two adjacent tyrosine residues involved in iron co-ordination, and demonstrate that, in contrast with mutation of equivalent residues in the N-lobe of human transferrin, the mutant FbpAs retain significant iron-binding affinity regardless of the nature of the replacement amino acid. The Y195A and Y196A FbpAs are not only capable of binding iron, but are proficient in mediating periplasm-to-cytoplasm iron transport in a reconstituted FbpABC pathway in a specialized Escherichia coli reporter strain. This indicates that their inability to mediate iron acquisition from transferrin is due to their inability to compete for iron with receptor-bound transferrin. Wild-type iron-loaded FbpA could be crystalized in a closed or open state depending upon the crystallization conditions. The synergistic phosphate anion was not present in the iron-loaded open form, suggesting that initial anchoring of iron was mediated by the adjacent tyrosine residues and that alternate pathways for iron and anion binding and release may be considered. Collectively, these results demonstrate that the presence of a twin-tyrosine motif common to many periplasmic iron-binding proteins is critical for initially capturing the ferric ion released by the outer-membrane receptor complex.
A family of norms with applications in quantum information theory
Authors: Johnston Nathaniel , Kribs David W.
Published: August 2010

We consider a family of vector and operator norms defined by the Schmidt decomposition theorem for quantum states. We use these norms to tackle two fundamental problems in quantum information theory: the classification problem for k-positive linear maps and entanglement witnesses, and the existence problem for nonpositive partial transpose bound entangled states. We begin with an analysis of the norms, showing that the vector norms can be explicitly calculated, and we derive several inequalities in order to bound the operator norms and compute them in special cases. We then use the norms to establish what appears to be the most general spectral test for k-positivity currently available, showing how it implies several other known tests as well as some new ones. Building on this work, we frame the nonpositive partial transpose bound entangled problem as a concrete problem on a specific limit, specifically that a particular entangled Werner state is bound entangled if and only if a certain norm inequality holds on a given family of projections.
Influence of period and amplitude of microwaviness on KH2PO4 crystal’s laser damage threshold
Authors: Chen Mingjun , Li Mingquan , Jiang Wei , Xu Qiao
Published: August 2010

The laser induced damage threshold (LIDT) has become a technical bottleneck which restricts the application and development of the inertial confinement fusion. Using single point diamond turning method to process KH2PO4 (KDP) crystals, the periodic microwaviness will be left on the machined surface which has a significant impact on the LIDT. In this paper, after acquiring the frequency information of machined surface of KDP crystals with the power spectral density method, we analyze quantitatively the influence of microwaviness on the LIDT of KDP crystal with the Fourier modal theory. Research results indicate that: the surface morphology of KDP crystal is consisted of the subwaviness with different characteristic spatial frequencies; and the reduced amount of the LIDT of KDP crystal leaded by such subwaviness is different; the experimental results of the LIDT are consistent with the theoretical calculations basically; for the machine tool and the processing technology we used, the leading frequency of microwaviness which caused the LIDT decreasing is between (350 μm)−1 and (30 μm)−1, especially between (90 μm)−1 and (180 μm)−1.
Electronic-resonance-enhanced coherent anti-Stokes Raman scattering of nitric oxide: Saturation and Stark effects
Authors: Chai Ning , Lucht Robert P. , Kulatilaka Waruna D. , Roy Sukesh , Gord James R.
Published: August 2010

A theoretical analysis of electronic-resonance-enhanced (ERE) coherent anti-Stokes Raman scattering (CARS) of NO is described. The time-dependent density-matrix equations for the nonlinear ERE-CARS process are derived and manipulated into a form suitable for direct numerical integration. In the ERE-CARS configuration considered in this paper, the pump and Stokes beams are far from electronic-resonance. The visible 532 and 591 nm laser beams are used to excite Q-branch Raman resonances in the vibrational bands of the X Π2 electronic state of NO. An ultraviolet probe beam at 236 nm is used to excite P-, Q-, or R-branch transitions in the (v′=0, v″=1) band of the A Σ2+−X Π2 electronic system of NO molecule. Experimental spectra are obtained either by scanning the ultraviolet probe beam while keeping the Stokes frequency fixed (probe scans) or by scanning the Stokes frequency while keeping the probe frequency fixed (Stokes scans). The calculated NO ERE-CARS spectra are compared with experimental spectra, and good agreement is observed between theory and experiment in terms of spectral peak locations and relative intensities. The effects of saturation of the two-photon Raman-resonant Q-branch transitions, the saturation of a one-photon electronic-resonant P-, Q-, or R-branch transitions in the A Σ2+−X Π2 electronic system, and the coupling of these saturation processes are investigated. The coupling of the saturation processes for the probe and Raman transitions is complex and exhibits behavior similar to that observed in the electromagnetic induced transparency process. The probe scan spectra are significantly affected by Stark broadening due to the interaction of the pump and Stokes radiation with single-photon resonances between the upper vibration-rotation probe level in the A Σ2+ electronic levels and vibration-rotation levels in higher lying electronic levels. The ERE-CARS signal intensity is found to be much less sensitive to variations in the collisional dephasing rates under saturation conditions.
Drive frequency dependent phase imaging in piezoresponse force microscopy
Authors: Bo Huifeng , Kan Yi , Lu Xiaomei , Liu Yunfei , Peng Song , Wang Xiaofei , Cai Wei , Xue Ruoshi , Zhu Jinsong
Published: August 2010

The drive frequency dependent piezoresponse (PR) phase signal in near-stoichiometric lithium niobate crystals is studied by piezoresponse force microscopy. It is clearly shown that the local and nonlocal electrostatic forces have a great contribution to the PR phase signal. The significant PR phase difference of the antiparallel domains are observed at the contact resonances, which is related to the electrostatic dominated electromechanical interactions of the cantilever and tip-sample system. Moreover, the modulation voltage induced frequency shift at higher eigenmodes could be attributed to the change of indention force depending on the modulation amplitude with a piezoelectric origin. The PR phase of the silicon wafer is also measured for comparison. It is certificated that the electrostatic interactions are universal in voltage modulated scanning probe microscopy and could be extended to other phase imaging techniques.
Piezoresponse force microscopy investigations of Aurivillius phase thin films
Authors: Keeney Lynette , Zhang Panfeng F. , Groh Claudia , Pemble Martyn E. , Whatmore Roger W.
Published: August 2010

The sol-gel synthesis and characterization of n≥3 Aurivillius phase thin films deposited on Pt/Ti/SiO2–Si substrates is described. The number of perovskite layers, n, was increased by inserting BiFeO3 into three layered Aurivillius phase Bi4Ti3O12 to form compounds such as Bi5FeTi3O15 (n=4). 30% of the Fe3+ ions in Bi5FeTi3O15 were substituted with Mn3+ ions to form the structure Bi5Ti3Fe0.7Mn0.3O15. The electromechanical responses of the materials were investigated using piezoresponse force microscopy and the results are discussed in relation to the crystallinity of the films as measured by x-ray diffraction.
Pyroelectric response of ferroelectric nanowires: Size effect and electric energy harvesting
Authors: Morozovska A. N. , Eliseev E. A. , Svechnikov G. S. , Kalinin S. V.
Published: August 2010

The size effect on pyroelectric response of ferroelectric nanowires is analyzed. The pyroelectric coefficient strongly increases with the wire radius decrease and diverges at critical radius Rcr corresponding to the size-driven transition into paraelectric phase. Size-driven enhancement of pyroelectric coupling leads to the giant pyroelectric current and voltage generation by the polarized ferroelectric nanoparticles in response to the temperature fluctuation. The maximum efficiency of the pyroelectric energy harvesting and bolometric detection is derived, and is shown to approach the Carnot limit for low temperatures.
Young’s modulus and density measurements of thin atomic layer deposited films using resonant nanomechanics
Authors: Ilic B. , Krylov S. , Craighead H. G.
Published: August 2010

Material properties of atomic layer deposited (ALD) thin films are of interest for applications ranging from wear resistance to high-k dielectrics in electronic circuits. We demonstrate the ability to simultaneously measure Young’s modulus (E) and density (ρ) of 21.2–21.5 nm ALD hafnia, alumina, and aluminum nitride ultrathin films by observing vibrations of nanomechanical cantilever beams. The nanomechanical structures were fabricated from a 250 nm thick single crystal silicon layer with varying length and width ranging from 6 μm to 10 μm and 45 nm to 1 μm, respectively. Our approach is based on an optical excitation and interferometric detection of in-plane and out-of plane vibrational spectra of single crystal silicon cantilevers before and after a conformal coating deposition of an ALD thin film. In conjunction with three-dimensional numerical finite element analysis, measurements of resonance carried out prior to the ALD revealed that while the influence of clamping compliance arising from the undercut of the sacrificial layer is significant for wider beams, the effect is less pronounced for both, narrower cantilevers and the in-plane vibrational response. Following the deposition, higher stiffness alumina films (E>ESi) showed an increase in the resonant frequency whereas lower stiffness (E<ESi) hafnia and aluminum nitride films decreased the natural frequency. From the measured spectral response, material properties were extracted using simple expressions for E and ρ in terms of measured in-plane and out-of-plane frequencies shifts. The derived model was based on an ideally clamped Euler–Bernoulli beam with effective bending stiffness and effective mass per unit length. In-plane and out-of-plane frequency measurements provided two equations that enabled simultaneous extraction of E and ρ. Three-dimensional finite element analysis showed that residual stress, nonideal clamping conditions, and the mismatch in the Poisson’s ratio between the deposited film and the nanomechanical oscillator have minor influence on the determined material properties. Experimental results obtained for the measured films were in excellent agreement with finite element simulations incorporating the geometric undercut caused by release of the suspended structures.
High homogeneity 25 cm low-energy rf ion source with inherent electron compensation
Authors: Dudin S. V. , Rafalskyi D. V. , Zykov A. V.
Published: August 2010

A 25 cm single-grid low-energy rf ion source with inherent electron compensation is described and characterized. Measurements were carried out using Ar and CF4 filling gas. The dependence of the ion beam current to the target as well as the current partition between the beam fast and slow ions on the rf discharge pressure for both filling gases is discussed. The unique ability of generation of coinciding ion and electron flows is demonstrated and the measured ion and electron energy distribution functions are presented as well. The developed broad ion beam source is able of providing 0.5–5 mA/cm2 current density in the low ion energy range of 50–250 eV, with possibility of independent current density and energy control. It is shown that complementing the rf plasma source with a profiling electrode allows for CF4 ion source operation attaining ±5% ion beam uniformity over 250 mm in diameter. The presented CF4 etching test results exhibit the possibility of highly directional anisotropic Si and SiO2 etching utilizing the developed single grid rf ion source.
Note: Fixture for characterizing electrochemical devices in-operando in traditional vacuum systems
Authors: Whaley Josh A. , McDaniel Anthony H. , El Gabaly Farid , Farrow Roger L. , Grass Michael E. , Hussain Zahid , Liu Zhi , Linne Mark A. , Bluhm Hendrik , McCarty Kevin F.
Published: August 2010

We describe a fixture that allows electrochemical devices to be studied under electrical bias in the type of vacuum systems commonly used in surface science. Three spring-loaded probes provide independent contacts for device operation and the characterization in vacuum or under in situ conditions with reactive gases. We document the robustness of the electrical contacts over large temperature changes and their reliability for conventional electrochemical measurements such as impedance spectroscopy. The optical access provided to the device enables the analysis by many techniques, as we demonstrate using x-ray photoelectron spectroscopy to measure local electrical potentials on a solid-oxide electrolyte device operating at high temperature in near-ambient pressure.
Multidimensional effects on relativistic electrons in an oblique shock wave
Authors: Shikii Kenta , Toida Mieko
Published: August 2010

Multidimensional effects on electron motion in a magnetosonic shock wave propagating obliquely to an external magnetic field are studied by means of a two-dimensional (two space coordinates and three velocities) relativistic, electromagnetic particle code. The simulations demonstrate that after trapping and energization in the main pulse of the shock wave, electrons can be detrapped from it keeping their ultrarelativistic energies. This detrapping is caused by magnetic fluctuations propagating along the wave front. Furthermore, some of the detrapped electrons can be accelerated to much higher energies by the shock wave because they can enter and exit the shock wave as a result of their gyromotions.
Enhancement of optical quality in metamorphic quantum wells using dilute nitride buffers
Authors: Song Yuxin , Wang Shumin , Lai Zonghe , Sadeghi Mahdad
Published: August 2010

Strong enhancement of optical quality in quantum wells by incorporating nitrogen in metamorphic InGaAs buffers grown on GaAs substrates is demonstrated. This has resulted in 3.7 or 5.4 times enhancement of photoluminescence intensity from the metamorphic quantum wells when using dilute nitride superlattice alone or adding nitrogen in a strain compensated GaAs/In0.3Al0.7As superlattice, respectively. This study shows great potentials by incorporating N in metamorphic buffers to further improve the quality of metamorphic optoelectronic devices.
Bioeconomic modelling to identify the relative importance of a range of critical control points for prime lamb production systems in south-west Victoria
Authors: Young J. M. , Thompson A. N. , Kennedy A. J.
Published: August 2010

Whole-farm decision making is complex as many factors influence the profitability of pasture-based lamb production systems and other influences such as skills and attitudes also affect the behaviours of individual farmers. In this paper we used bioeconomic modelling to identify the relative importance of manipulating components of lamb production systems in south-west Victoria and quantified their likely impacts on whole-farm profitability. Four lamb production systems that varied in relation to the genotype of the ewes and the time of sale of the lambs were examined in the analysis. Two ‘systems’ were based on first-cross Border Leicester × Merino ewes that were mated to a terminal sire and the lambs were either sold as finished slaughter lambs at 45 kg liveweight or as stores at weaning at 30 kg liveweight. The other two ‘systems’ were based on a self-replacing composite breed (Romney × Coopworth base) and the lambs were sold as finished slaughter lambs or stores.
Based on the assumptions used the analysis highlighted that the potential economic gain per unit change was high for several factors examined and the relative importance of these critical control points differed between production systems. Matching lamb turn-off (finished or store) to existing ewe genotype improved profitability by more than $100/ha or 50% and optimising pasture utilisation was also important regardless of production system. A 20% increase in pasture utilisation up to the optimum increased whole-farm profit by more than $100/ha. The impacts of improving pasture growth just after the break of season and through early winter on whole-farm profit were even greater. An extra 20 kg of pasture growth per day at this time of the year is potentially worth about $200/ha due to increases in whole-farm stocking rate. Extra pasture growth in early summer also has significant value for later lambing flocks. When farmers have optimised these factors the second-order control points were cost of replacement ewes for the first-cross system, age at first mating and reproduction efficiency in adult ewes.
The management and production factors that will provide the greatest return on effort for individual farmers will depend on the potential economic gain per unit change in the target factor, their current management and production levels and the ease with which the management change or increase in production potential can be achieved in the farming system.
Sheep category can be classified using machine learning techniques applied to fatty acid profiles derivatised as trimethylsilyl esters
Authors: Watkins P. J. , Clifford D. , Rose G. , Allen D. , Warner R. D. , Dunshea F. R. , Pethick D. W.
Published: August 2010

Eruption of permanent incisors (dentition) is used as a proxy for age for defining meat quality in Australian sheep meat. However, this approach may not be reliable. While not presently available, an objective method could be used to determine sheep age, and thus sheep category, which would then potentially remove any inaccuracies that may occur in classifying sheep meat product. Statistical classification algorithms have been successfully used in bioinformatics. In this paper we review the performance of three algorithms (support vector machines, recursive partitioning and random forests) for determining sheep age. The algorithms were applied to the measured fatty acid profiles of fat samples from 533 carcasses; 254 lamb (<1 year old), 131 hogget (~1–2 years old) and 148 mutton (>2 years old) samples. Three data pretreatments (range transformation, column mean centering and range transformation with mean centering) were also examined to determine their impact on the performance of the algorithms. The random forests algorithm, when applied to mean-centred data, gave 100% predictive accuracy when classifying sheep category. This approach could be used for the development of an objective test for determining sheep age and category.
A new classification for subtribe Pterostylidinae (Orchidaceae), reaffirming Pterostylis in the broad sense
Authors: Janes Jasmine K. , Duretto Marco F.
Published: August 2010

A new classification for subtribe Pterostylidinae (Orchidaceae) is formally described in which there is one genus, Pterostylis R.Br., two subgenera and 10 sections. Five new combinations are made for this classification at the ranks of subgenus and section, viz. Pt. subg. Oligochaetochilus (Szlach.) Janes & Duretto, Pt. sect. Parviflorae (Benth.) Janes & Duretto, Pt. sect. Pharochilum (D.L.Jones & M.A.Clem.) Janes & Duretto, Pt. sect. Stamnorchis (D.L.Jones & M.A.Clem.) Janes & Duretto and Pt. sect. Urochilus (D.L.Jones & M.A.Clem.) Janes & Duretto. Pt. ser. Parviflorae Benth. is lectotypified. To complete the revision, seven new species-level combinations are made for two species from Western Australia, one from New South Wales and four from Queensland, viz. Pt. anaclasta (D.L.Jones) Janes & Duretto, Pt. extranea (D.L.Jones) Janes & Duretto, Pt. pearsonii (D.L.Jones) Janes & Duretto, Pt. pedina (D.L.Jones) Janes & Duretto, Pt. sinuata (D.L.Jones) Janes & Duretto, Pt. timothyi (D.L.Jones) Janes & Duretto and Pt. thulia (D.L.Jones) Janes & Duretto.
Ancient DNA reveals extreme egg morphology and nesting behavior in New Zealand’s extinct moa
Authors: Huynen Leon , Gill Brian J. , Millar Craig D. , Lambert David M.
Published: August 2010

New Zealand's extinct flightless moa radiated rapidly into a large number of morphologically diverse species, which produced an equally large range of egg morphologies. The exact number of moa species, as well as the characteristics of the eggs they laid, remains contentious. Moreover, like most extinct species, we understand little about their nesting and incubation habits. We used a modified ancient DNA extraction procedure to recover exogenous mitochondrial and nuclear DNA from the inside and outside surfaces of moa eggs. We used sequences from the inside of 69 eggshells to directly assign these remains to seven of the 10 currently recognized moa species. In addition we were able to assign, to the species level, six of the rare reconstructed “whole” eggs. These molecular results enabled us to identify two distinct lineages within the genusEuryapteryx.Members of these lineages differed in eggshell thickness, with one lineage being characterized by a relatively thin eggshell. Unexpectedly, several thin-shelled eggs were also shown to belong to the heaviest moa of the generaDinornis, EuryapteryxandEmeus, making these, to our knowledge, the most fragile of all avian eggs measured to date. Moreover, sex-specific DNA recovered from the outer surfaces of eggshells belonging to species ofDinornisandEuryapteryxsuggest that these very thin eggs were likely to have been incubated by the lighter males. The thin nature of the eggshells of these larger species of moa, even if incubated by the male, suggests that egg breakage in these species would have been common if the typical contact method of avian egg incubation was used.
Embryonic gonadotropin-releasing hormone signaling is necessary for maturation of the male reproductive axis
Authors: Wen Shuping , Ai Wei , Alim Zahara , Boehm Ulrich
Published: August 2010

Gonadotropin-releasing hormone (GnRH) signaling regulates reproductive physiology in mammals. GnRH is released by a subset of hypothalamic neurons and binds to GnRH receptor (GnRHR) on gonadotropes in the anterior pituitary gland to control production and secretion of gonadotropins that in turn regulate the activity of the gonads. Central control of reproduction is well understood in adult animals, but GnRH signaling has also been implicated in the development of the reproductive axis. To investigate the role of GnRH signaling during development, we selectively ablated GnRHR-expressing cells in mice. This genetic strategy permitted us to identify an essential stage in male reproductive axis development, which depends on embryonic GnRH signaling. Our experiments revealed a striking dichotomy in the gonadotrope population of the fetal anterior pituitary gland. We show that luteinizing hormone-expressing gonadotropes, but not follicle-stimulating hormone-expressing gonadotropes, express the GnRHR at embryonic day 16.75. Furthermore, we demonstrate that an embryonic increase in luteinizing hormone secretion is needed to promote development of follicle-stimulating hormone-expressing gonadotropes, which might be mediated by paracrine interactions within the pituitary. Moreover, migration of GnRH neurons into the hypothalamus appeared normal with appropriate axonal connections to the median eminence, providing genetic evidence against autocrine regulation of GnRH neurons. Surprisingly, genetic ablation of GnRHR expressing cells significantly increased the number of GnRH neurons in the anterior hypothalamus, suggesting an unexpected role of GnRH signaling in establishing the size of the GnRH neuronal population. Our experiments define a functional role of embryonic GnRH signaling.
Early evidence (
ca.
12,000 B.P.) for feasting at a burial cave in Israel
Authors: Munro Natalie D. , Grosman Leore
Published: August 2010

Feasting is one of humanity's most universal and unique social behaviors. Although evidence for feasting is common in the early agricultural societies of the Neolithic, evidence in pre-Neolithic contexts is more elusive. We found clear evidence for feasting on wild cattle and tortoises at Hilazon Tachtit cave, a Late Epipaleolithic (12,000 calibrated years B.P.) burial site in Israel. This includes unusually high densities of butchered tortoise and wild cattle remains in two structures, the unique location of the feasting activity in a burial cave, and the manufacture of two structures for burial and related feasting activities. The results indicate that community members coalesced at Hilazon to engage in special rituals to commemorate the burial of the dead and that feasts were central elements in these important events. Feasts likely served important roles in the negotiation and solidification of social relationships, the integration of communities, and the mitigation of scalar stress. These and other social changes in the Natufian period mark significant changes in human social complexity that continued into the Neolithic period. Together, social and economic change signal the very beginning of the agricultural transition.
Insulin-like growth factor 1 treatment extends longevity in a mouse model of human premature aging by restoring somatotroph axis function
Authors: Mariño Guillermo , Ugalde Alejandro P. , Fernández Álvaro F. , Osorio Fernando G. , Fueyo Antonio , Freije José M. P. , López-Otín Carlos
Published: August 2010

Zmpste24 (also called FACE-1) is a metalloproteinase involved in the maturation of lamin A, an essential component of the nuclear envelope. Zmpste24-deficient mice exhibit multiple defects that phenocopy human accelerated aging processes such as Hutchinson–Gilford progeria syndrome. In this work, we report that progeroid

Zmpste24
-/

−
mice present profound transcriptional alterations in genes that regulate the somatotroph axis, together with extremely high circulating levels of growth hormone (GH) and a drastic reduction in plasma insulin-like growth factor 1 (IGF-1). We also show that recombinant IGF-1 treatment restores the proper balance between IGF-1 and GH in

Zmpste24
-/

−
mice, delays the onset of many progeroid features, and significantly extends the lifespan of these progeroid animals. Our findings highlight the importance of IGF/GH balance in longevity and may be of therapeutic interest for devastating human progeroid syndromes associated with nuclear envelope abnormalities.
In utero exposure to dioxin causes neocortical dysgenesis through the actions of p27
Kip1
Authors: Mitsuhashi Takayuki , Yonemoto Junzo , Sone Hideko , Kosuge Yasuhiro , Kosaki Kenjiro , Takahashi Takao
Published: August 2010

Dioxins have been reported to exert various adverse effects, including cell-cycle dysregulation in vitro and impairment of spatial learning and memory after in utero exposure in rodents. Furthermore, children born to mothers who are exposed to dioxin analogs polychlorinated dibenzofurans or polychlorinated biphenyls have developmental impairments in cognitive functions. Here, we show that in utero exposure to dioxins in mice alters differentiation patterns of neural progenitors and leads to decreased numbers of non-GABAergic neurons and thinner deep neocortical layers. This reduction in number of non-GABAergic neurons is assumed to be caused by accumulation of cyclin-dependent kinase inhibitor p27
Kip1
in nuclei of neural progenitors. Lending support to this presumption, mice lacking p27
Kip1
are not susceptible to in utero dioxin exposure. These results show that environmental pollutants may affect neocortical histogenesis through alterations of functions of specific gene(s)/protein(s) (in our case, dioxins), exerting adverse effects by altering functions of p27
Kip1
.
Elr-type proteins protect
Xenopus Dead end
mRNA from miR-18-mediated clearance in the soma
Authors: Koebernick Katja , Loeber Jana , Arthur Patrick Kobina , Tarbashevich Katsiaryna , Pieler Tomas
Published: August 2010

Segregation of the future germ line defines a crucial cell fate decision during animal development. In
Xenopus
, germ cells are specified by inheritance of vegetally localized maternal determinants, including a group of specific mRNAs. Here, we show that the vegetal localization elements (LE) of
Xenopus Dead end (XDE)
and of several other germ-line-specific, vegetally localized transcripts mediate germ cell-specific stabilization and somatic clearance of microinjected reporter mRNA in
Xenopus
embryos. The part of
XDE
-LE critical for somatic RNA clearance exhibits homology to zebrafish
nanos1
and appears to be targeted by
Xenopus
miR-18 for somatic mRNA clearance.
Xenopus
Elr-type proteins of the vegetal localization complex can alleviate somatic RNA clearance of microinjected
XDE
-LE and endogenous
XDE
mRNA. ElrB1 synergizes with
Xenopus
Dead end protein in the stabilization of
XDE
-LE mRNA. Taken together, our findings unveil a functional link of vegetal mRNA localization and the protection of germ-line mRNAs from somatic clearance.
Central serotonin neurons are required for arousal to CO
2
Authors: Buchanan Gordon F. , Richerson George B.
Published: August 2010

There is a long-standing controversy about the role of serotonin in sleep/wake control, with competing theories that it either promotes sleep or causes arousal. Here, we show that there is a marked increase in wakefulness when all serotonin neurons are genetically deleted in mice hemizygous for ePet1-Cre and homozygous for floxed
Lmx1b
(

Lmx1b
f/f/p

). However, this only occurs at cool ambient temperatures and can be explained by a thermoregulatory defect that leads to an increase in motor activity to generate heat. Because some serotonin neurons are stimulated by CO
2
, and serotonin activates thalamocortical networks, we hypothesized that serotonin neurons cause arousal in response to hypercapnia. We found that

Lmx1b
f/f/p

mice completely lacked any arousal response to inhalation of 10% CO
2
(with 21% O
2
in balance N
2
) but had normal arousal responses to hypoxia, sound, and air puff. We propose that serotonin neurons mediate the potentially life-saving arousal response to hypercapnia. Impairment of this response may contribute to sudden unexpected death in epilepsy, sudden infant death syndrome, and sleep apnea.
The serine/arginine-rich protein SF2/ASF regulates protein sumoylation
Authors: Pelisch Federico , Gerez Juan , Druker Jimena , Schor Ignacio E. , Muñoz Manuel J. , Risso Guillermo , Petrillo Ezequiel , Westman Belinda J. , Lamond Angus I. , Arzt Eduardo , Srebrow Anabella
Published: August 2010

Protein modification by conjugation of small ubiquitin-related modifier (SUMO) is involved in diverse biological functions, such as transcription regulation, subcellular partitioning, stress response, DNA damage repair, and chromatin remodeling. Here, we show that the serine/arginine-rich protein SF2/ASF, a factor involved in splicing regulation and other RNA metabolism-related processes, is a regulator of the sumoylation pathway. The overexpression of this protein stimulates, but its knockdown inhibits SUMO conjugation. SF2/ASF interacts with Ubc9 and enhances sumoylation of specific substrates, sharing characteristics with already described SUMO E3 ligases. In addition, SF2/ASF interacts with the SUMO E3 ligase PIAS1 (protein inhibitor of activated STAT-1), regulating PIAS1-induced overall protein sumoylation. The RNA recognition motif 2 of SF2/ASF is necessary and sufficient for sumoylation enhancement. Moreover, SF2/ASF has a role in heat shock-induced sumoylation and promotes SUMO conjugation to RNA processing factors. These results add a component to the sumoylation pathway and a previously unexplored role for the multifunctional SR protein SF2/ASF.
Spontaneous EEG oscillations reveal periodic sampling of visual attention
Authors: Busch Niko A. , VanRullen Rufin
Published: August 2010

An important effect of sustained attention is the facilitation of perception. Although the term “sustained” suggests that this beneficial effect endures continuously as long as something is attended, we present electrophysiological evidence that perception at attended locations is actually modulated periodically. Subjects detected brief light flashes that were presented peripherally at locations that were either attended or unattended. We analyzed the correlation between detection performance for attended and unattended stimuli and the phase of ongoing EEG oscillations, which relate to subsecond fluctuations of neuronal excitability. Although on average, detection performance was improved by attention—indicated by reduced detection thresholds at attended locations—we found that detection performance for attended stimuli actually fluctuated over time along with the phase of spontaneous oscillations in the θ (≈7 Hz) frequency band just before stimulus onset. This fluctuation was absent for unattended stimuli. This pattern of results suggests that “sustained” attention in fact exerts its facilitative effect on perception in a periodic fashion.