bluuebunny/crossref_metadata_2025 huggingface dataset:
Resolving the mystery of the quasars?
Authors: Morrison Philip
Published: December 2012

The quasar continues to rank both as one of the most baffling objects in the universe and one most capable of inspiring heated argument. But it is going on 10 years since we first became aware of the unusual properties of quasars and, although no one is foolhardy enough to claim to have solved the mystery, we have over this time accumulated a fair amount of information about quasars. My thesis is that the available data can be fitted by a relatively conventional picture of quasars as the condensed central cores of galaxies occuring at a certain point in their evolution. Although others share this view, a number of my colleagues and critics in the business of quasar theories do not. I ask their indulgence for this simplified and undocumented presentation of physical arguments and encourage them to seek—if they have not already used up—equal time.
Gravitational waves—a progress report
Authors: Logan Jonothan L.
Published: December 2012

For over ten years Joseph Weber has conducted a search for the gravitational radiation predicted by general relativity. His recent results indicate an apparent powerful source of radiation at the galactic center. More than a dozen groups have now joined the effort, and several have reported preliminary results; so far no one has reproduced Weber's findings. The pace of research is accelerating, and this appears to be a good time to discuss the current experiments and those planned for the next few years.
Low-temperature anomalies in the thermal conductivity of plastically deformed crystals caused by phonon-kink scattering
Authors: van Ostaay J. A. M. , Mukhin S. I. , Mezhov-Deglin L. P.
Published: December 2012

Previous experimental studies of plastically deformed lead crystals in the superconducting state have revealed strong anomalies in its thermal conductivity. Similar effects have also been found for the thermal conductivity of bent 4He samples. Until now, a theoretical explanation for these results has been lacking. In this paper we introduce the process of phonon-kink scattering and show that it qualitatively explains the experimentally observed anomalies.
Possibility of large superconducting gaps in the presence of quantum fluctuations
Authors: Zhilyaev I. N.
Published: December 2012

According to the BCS model, the probability vk2 of filling electronic states as a function of kinetic energy is smeared out. A modified mechanism for formation of vk2 that includes fluctuations near quantum phase transitions is proposed. The superconducting gap Δ for materials with parameters close to those of HTSC materials is estimated when fluctuations are present and the result is comparable to actual observations. The major characteristics of the proposed model resemble those of the model used to describe HTSC materials.
Method of trial distribution function for quantum turbulence
Authors: Nemirovskii Sergey K.
Published: December 2012

In order to study quantum turbulence it is necessary to calculate the various characteristics of the vortex tangle (VT). Some of the "crude" quantities can be expressed directly via the total length of vortex lines (per unit of volume) or the vortex line density L (t) and the structure parameters of the VT. Other more “subtle” quantities require knowledge of the vortex line configurations {s(ξ, t)}. Usually, the corresponding calculations are carried out with the use of more or less truthful speculations concerning arrangement of the VT. In this paper we review other ways of solving this problem. It is based on the trial distribution functional (TDF) in the space of vortex loop configurations. The TDF is constructed on the basis of well established properties of the vortex tangle. It is designed to calculate various averages taken over stochastic vortex loop configurations. In this paper we also review several applications of the use of this model to calculate some important characteristics of the vortex tangle. In particular, we discussed the average superfluid mass current J induced by vortices, and its dynamics. We also describe the diffusion-like processes in the nonuniform vortex tangle and the propagation of turbulent fronts.
Determination of optical and microstructural parameters of ceria films
Authors: Oh Tae-Sik , Tokpanov Yury S. , Hao Yong , Jung WooChul , Haile Sossina M.
Published: December 2012

Light-matter interactions are of tremendous importance in a wide range of fields from solar energy conversion to photonics. Here the optical dispersion behavior of undoped and 20 mol. % Sm doped ceria thin films, both dense and porous, were evaluated by UV-Vis optical transmission measurements, with the objective of determining both intrinsic and microstructural properties of the films. Films, ranging from 14 to 2300 nm in thickness, were grown on single crystal YSZ(100) and MgO(100) using pulsed laser deposition (both dense and porous films) and chemical vapor deposition (porous films only). The transmittance spectra were analyzed using an in-house developed methodology combining full spectrum fitting and envelope treatment. The index of refraction of ceria was found to fall between 2.65 at a wavelength of 400 nm and 2.25 at 800 nm, typical of literature values, and was relatively unchanged by doping. Reliable determination of film thickness, porosity, and roughness was possible for films with thickness ranging from 500 to 2500 nm. Physically meaningful microstructural parameters were extracted even for films so thin as to show no interference fringes at all.
Spin-glass-like freezing in spin-chain compounds Ca3Co2−xMnxO6: Effect of disorder
Authors: Ouyang Z. W. , Sheng S. S. , Chen J. , Shi X. M. , Ruan M. Y. , Xia Z. C. , Li L.
Published: December 2012

We have illustrated the presence of spin-glass-like freezing in the Mn-doped spin-chain compounds Ca3Co2−xMnxO6, which was not reported previously. With increasing Mn composition, the magnetic relaxation due to spin freezing is gradually suppressed. Interestingly, the magnetization in the intermediate Mn compositions relaxes more slowly (characteristic time is significantly enhanced) than those in x = 0.0 and 1.0. This could be understood within the framework of disorder with randomness or imperfections, which plays an important role in the formation of spin-glass-like feature in intermediate Mn compositions, quite different from the cases in x = 0.0 with strong spin frustration and in x ∼ 1.0 with perfect Co/Mn ionic order.
Effects of two transversal finite dimensions in long microchannel: Analytical approach in slip regime
Authors: Méolans J. G. , Hadj Nacer M. , Rojas M. , Perrier P. , Graur I.
Published: December 2012

An analytical approach has been developed to take account of the influence of the lateral walls on a stationary isothermal gas flow through a rectangular microchannel. The study concerns pressure-gradient-driven flows in channels where the length is large compared to the critical smallest dimension, namely, the channel height. The calculation of the bulk velocity is based on the Stokes equation treatment and uses the property of the Laplace operator. This novel method remains very easy to use when the second order term with respect to the Knudsen number is taken into account in the wall boundary conditions. The method is notably of high practical interest when applied to rectangular-cross-section microchannels that connect upstream and downstream high capacity reservoirs. The mass flow rates measured along such systems are fitted to first or second order polynomial forms following the mean Knudsen number of the flow. The present calculation also leads to a completely explicit second order expression for the mass flow rate. Thus, the first and second order experimental and theoretical coefficients can be identified immediately, allowing direct evaluations of physical gas-wall interaction features, in particular, the first, second order slip and the accommodation coefficients. An example of the implementation of the proposed technique is given. The slip and accommodation coefficients are extracted from the measurements of the mass flow rate through microchannels of rectangular cross-section.
Stability and reconstruction of inverse gravity films (Review Article)
Authors: Kolmakov G. , Kono K. , Levchenko A. , Leiderer P. , Shikin V.
Published: December 2012

The paper traces retrospectively the development of the concept of stability of liquid films formed on downward facing surfaces (inversed gravity films). The original scenario of the instability development proposed by Rayleigh does not contain the concept of a critical state, after reaching which the flat stable inversed gravity film transforms into a corrugated modification whereas the film thickness is slightly increased. Both the general understanding of the events which occurred at the critical point, and the possibility of discussing the full-scale instability including its definition and various scenarios of inversed gravity films reconstructions, have been developed only recently. The aim of this study is to outline a consistent picture of droplet instability at its different stages starting from the threshold point and up to the formation of a stationary corrugation (surface shape reconstruction). The computational part of the paper is complemented with a series of specially performed experiments, which confirm the main predictions of the theory.
Ab initio quartic force field of stannane and rotational analysis of the ν1 infrared band of H120SnD3
Authors: Fusina Luciano , Nivellini Gian Domenico , Salzillo Tommaso , Lamarra Manuele , Tarroni Riccardo
Published: December 2012

Stannane, SnH4, has been studied both theoretically, using high-level ab initio methods, and experimentally, using high-resolution spectroscopy to analyze the Sn−H stretching fundamental band of the H120SnD3 isotopologue. The geometry and the anharmonic force field of the molecule have been calculated ab initio, using the coupled-cluster with single, double, and perturbative triple excitations level of theory. H120SnD3, present as minor isotopologue in 120SnD4, has been studied by Fourier transform spectroscopy at an effective resolution of ca. 0.005 cm−1 near 1900 cm−1 and the ν1 band was identified. About 360 ro−vibration transitions with J′ up to 18 and K up to 10 have been assigned. Since the spectrum evidenced the existence of some perturbations, the transitions were analyzed either neglecting, or including in the model A1/E Coriolis−type interactions with nearby dark states. The standard deviation of the fits, ca. 1.5 × 10−3 cm−1, is about one order of magnitude larger than the estimated experimental precision, and is only slightly dependent on the adopted model. The spectroscopic parameters obtained from this and from previous analyses of stannane isotopologues have been compared with the theoretical results. The theoretical force field is also used to obtain semi-experimental harmonic frequencies and the equilibrium geometry.
Stable glasses of indomethacin and α,α,β-tris-naphthylbenzene transform into ordinary supercooled liquids
Authors: Sepúlveda A. , Swallen Stephen F. , Kopff Laura A. , McMahon Robert J. , Ediger M. D.
Published: December 2012

Secondary ion mass spectrometry has been used to characterize translational motion in vapor-deposited glasses of indomethacin (IMC) and α,α,β-tris-naphthylbenzene (TNB). Vapor deposition onto substrates at ∼0.99 Tg produced ordinary glasses that evolve according to Fickian diffusion during annealing. The resulting self-diffusion coefficients for the supercooled liquids are in good agreement with previous reports. Deposition onto substrates at 0.85 Tg produced highly stable glasses that transform with a propagating front mechanism. In contrast to previous reports, the liquid produced by this transformation has the same translational mobility as the ordinary supercooled liquid; we associate this result with lower impurity levels in the current samples. The front velocities for both TNB and IMC stable glasses are very similar functions of the translational self-diffusion coefficients of the supercooled liquids, consistent with view that the growth front velocity is controlled by mobility in the liquid adjacent to the stable glass.
Electronic spectroscopy of ytterbium in a neon matrix
Authors: Lambo R. , Buchachenko A. A. , Wu L. , Tan Y. , Wang J. , Sun Y. R. , Liu A.-W. , Hu S.-M.
Published: December 2012

The low-lying electronic states of Yb isolated in a solid Ne matrix are characterized through absorption and emission spectroscopy. The absorption spectra of matrix isolated Yb while pumped into its triplet states have been recorded for the first time and the 6s6p 3PJ → 5d6s 3D1, 2 transition frequencies obtained. Under matrix conditions, the structure of these states is found to be qualitatively the same as in the free atom, but the intersystem crossing rate is observed to be several orders of magnitude greater. A proposed explanation for this is curve crossings between the bound potential energy surface correlated to the 6s6p 1P1 state and the potential energy surfaces correlated to the 5d6s 3D1, 2 states in isolation. The potentials of the Yb·Ne dimer in its lowest electronic states are computed ab initio and used in a pairwise cluster model to explicitly demonstrate these curve crossings.
Physics of a magnetic filter for negative ion sources. I. Collisional transport across the filter in an ideal, 1D filter
Authors: Boeuf J. P. , Chaudhury B. , Garrigues L.
Published: December 2012

Magnetic filters are used in negative ion sources for neutral beam injection in fusion devices to reduce the electron temperature in the extraction region in order to limit negative ion destruction by fast electrons. The drop in electron temperature through the filter is due to the enhanced residence time and collisional energy losses of electrons trapped in the magnetic field. The mechanisms controlling particle and energy transport through the magnetic filter in negative ion sources of the ITER type are still not clear and the aim of this paper is to clarify and quantify these mechanisms. A particle-in-cell Monte Carlo simulation is used to revisit and analyze the role and operation of the magnetic filter in an “ideal” one-dimensional configuration and to study the stability of the one-dimensional solution in a two-dimensional configuration with periodic boundary conditions. The roles of collisions and instabilities on electron transport through the filter are discussed. The influence of a more realistic geometry on electron transport through the filter is analyzed in the companion paper [Boeuf et al., Phys. Plasmas 19, 113510 (2012)].
Single electron transport through site-controlled InAs quantum dots
Authors: Cha K. M. , Shibata K. , Hirakawa K.
Published: December 2012

We have grown site- and size-controlled InAs quantum dots (QDs) in shallow nanoholes prepared using atomic force microscope-assisted anodic nano-oxidation and subsequent etching, and investigated their transport properties by depositing metal nanogap electrodes on a single QD. We have observed clear diamond-like patterns in Coulomb stability diagrams, indicating that the fabricated single QD transistors operate as single electron transistors and that the site-controlled QDs have a good crystalline quality. Furthermore, we show that the charging energies and the orbital quantization energies can be controlled over a wide range by controlling the size of the QDs.
Low-power resistive switching in Au/NiO/Au nanowire arrays
Authors: Brivio S. , Tallarida G. , Perego D. , Franz S. , Deleruyelle D. , Muller C. , Spiga S.
Published: December 2012

Arrays of vertical nanowires structured in Au/NiO/Au segments with 50 nm diameter are characterized by conductive atomic force microscopy to investigate unipolar resistive switching in NiO at the nanoscale. The switching cycles are characterized by extremely low power consumption down to 1.3 nW, which constitutes a significant improvement in nanowire-based resistive switching memory devices. The trend of the reset current as a function of the set resistance, typical of unipolar memories, is extended to a much wider current range than what is reported in literature, confirming the role of Joule heating in the reset process for very low reset currents.
Parametric excitation of a micro Coriolis mass flow sensor
Authors: Droogendijk H. , Groenesteijn J. , Haneveld J. , Sanders R. G. P. , Wiegerink R. J. , Lammerink T. S. J. , Lötters J. C. , Krijnen G. J. M.
Published: December 2012

We demonstrate that a micro Coriolis mass flow sensor can be excited in its torsional movement by applying parametric excitation. Using AC-bias voltages for periodic electrostatic spring softening, the flow-filled tube exhibits a steady vibration at suitable voltage settings. Measurements show that the sensor for this type of excitation can be used to measure water flow rates within a range of 0 ± 500 μl/h with an accuracy of 1% full scale error.
Characteristics of ion acoustic solitary waves in a negative ion plasma with superthermal electrons
Authors: Rouhani M. R. , Ebne Abbasi Z.
Published: December 2012

The behavior of ion acoustic solitons in a plasma including positive and negative ions and kappa distributed electrons is studied, using both small amplitude and arbitrary amplitude approaches. The existence regions of compressive and rarefactive solitons will depend on negative to positive ion density ratio (ν) and kappa parameter as well as positive to negative ion mass ratio (Q). The numerical analysis of Sagdeev potential shows that for a chosen plasma with fixed Q, the existence regime of compressive solitons is decreased (increased) by increasing density ratio (kappa parameter), while for rarefactive solitons these conditions are quite opposite. Additionally, the possibility of propagation of both compressive and rarefactive subsonic solitons is investigated. It is found that by increasing negative ions, the existence domains of subsonic solitons are decreased, so that in excess of negative ions subsonic solitons will not propagate even at the presence of superthermal electrons. Indeed, there is a critical negative ion density ratio for all values of kappa, above that only supersonic solitons are observed. Furthermore, in addition to the previous results based on Cairns-distributed electrons [R. A. Cairns et al., Geophys. Res. Lett. 22, 2709 (1995)], which predicted that both compressive and rarefactive solitons can coexist simultaneously, we have also found the regions of ν and κ in which either positive or negative potentials are permitted (i.e., not together). This research will be helpful in understanding the properties of space and laboratory plasmas containing negative ions with energetic electrons.
Raman shifted third harmonic generation of upper hybrid radiation in a plasma
Authors: K. K. Magesh Kumar , Singh Ranjeet , Tripathi V. K.
Published: December 2012

Raman shifted third harmonic generation of upper hybrid radiation is proposed and studied. In the presence of ambient magnetic field, the plasma wave present in the system produces electron density ripple (perturbation) which couples with the velocity imparted by the nonlinear ponderomotive force at twice the laser frequency producing the Raman shifted third harmonic field. The wave vector of the plasma wave provides the uncompensated momentum necessary for phase matching condition. The applied magnetic field can be adjusted to have the phase matching for the given plasma frequency. The energy conversion ratio from pump to the Raman shifted third harmonic generation of upper hybrid radiation is analyzed.
Study of fast electron jet produced from interaction of intense laser beam with solid target at oblique incidence
Authors: Sanyasi Rao Bobbili , Arora Vipul , Anant Naik Prasad , Dass Gupta Parshotam
Published: December 2012

Fast electrons generated along target normal direction from the interaction of intense ultrashort Ti:sapphire laser pulses (λ0 = 800 nm) with planar copper target at 45° incidence angle have been experimentally studied under different interaction conditions. Angular spread and energy spectrum of the fast electrons was measured for both p- and s-polarized laser irradiation at intensities in the range 4 × 1016 – 4 × 1017 W/cm2 (for a fixed pulse duration of 45 fs) and for pulse duration in the range 45 fs–1.2 ps (for a fixed laser fluence of 1.8 × 104 J/cm2). The fast electrons were observed consistently along the target normal direction over the entire range of interaction conditions in the form of a collimated jet, within a half cone angle of 20°. The fast electrons have continuous energy spectrum with effective temperature 290 keV and 160 keV, respectively, for p- and s-polarized 45 fs laser pulse irradiation at intensity 4 × 1017 W/cm2. Scaling laws for temperature of fast electrons with laser intensity and pulse duration were obtained. The experimental results have been explained on the basis of laser absorption and fast electron generation through the resonance absorption mechanism.
The hidden cost of private health insurance in Australia
Authors: Seah Davinia S. E. , Cheong Timothy Z. , Anstey Matthew H. R.
Published: December 2012

The provision of health services in Australia currently is primarily financed by a unique interaction of public and private insurers. This commentary looks at a loophole in this framework, namely that private insurers have to date been able to avoid funding healthcare for some of their policy holders, as it is not a requirement to use private insurance when treatment occurs in Australian public hospitals.
Dynamic Cleavages of ‘Welfare Rights and Duties’ in Public Attitude Towards Old-age Pensions
Authors: Ahn Sang-Hoon , Kim Soo-Wan
Published: December 2012

This study investigated public attitudes towards pension spending in welfare states. By utilising a dataset covering 21 different Western European countries and conducting a multi-level analyses, three main findings resulted. First, as the welfare status model suggests, the status of welfare duties as well as the status of welfare rights proved to play a key role in shaping the political cleavages over public pensions at both macro- and micro-levels. Second, age and gender also seem to be significant sources of cleavage in addition to class-related variables. Finally, the study examined empirically the interaction effect of age and class-related factors to reveal that class-based interests offset generational interests.
The evolution of a visual-to-auditory sensory substitution device using interactive genetic algorithms
Authors: Wright Thomas , Ward Jamie
Published: December 2012

Sensory substitution is a promising technique for mitigating the loss of a sensory modality. Sensory substitution devices (SSDs) work by converting information from the impaired sense (e.g., vision) into another, intact sense (e.g., audition). However, there are a potentially infinite number of ways of converting images into sounds, and it is important that the conversion takes into account the limits of human perception and other user-related factors (e.g., whether the sounds are pleasant to listen to). The device explored here is termed “polyglot” because it generates a very large set of solutions. Specifically, we adapt a procedure that has been in widespread use in the design of technology but has rarely been used as a tool to explore perception—namely, interactive genetic algorithms. In this procedure, a very large range of potential sensory substitution devices can be explored by creating a set of “genes” with different allelic variants (e.g., different ways of translating luminance into loudness). The most successful devices are then “bred” together, and we statistically explore the characteristics of the selected-for traits after multiple generations. The aim of the present study is to produce design guidelines for a better SSD. In three experiments, we vary the way that the fitness of the device is computed: by asking the user to rate the auditory aesthetics of different devices (Experiment 1), and by measuring the ability of participants to match sounds to images (Experiment 2) and the ability to perceptually discriminate between two sounds derived from similar images (Experiment 3). In each case, the traits selected for by the genetic algorithm represent the ideal SSD for that task. Taken together, these traits can guide the design of a better SSD.
Rho and NusG suppress pervasive antisense transcription in Escherichia coli
Authors: Peters Jason M. , Mooney Rachel A. , Grass Jeffrey A. , Jessen Erik D. , Tran Frances , Landick Robert
Published: December 2012

Despite the prevalence of antisense transcripts in bacterial transcriptomes, little is known about how their synthesis is controlled. We report that a major function of the Escherichia coli termination factor Rho and its cofactor, NusG, is suppression of ubiquitous antisense transcription genome-wide. Rho binds C-rich unstructured nascent RNA (high C/G ratio) prior to its ATP-dependent dissociation of transcription complexes. NusG is required for efficient termination at minority subsets (∼20%) of both antisense and sense Rho-dependent terminators with lower C/G ratio sequences. In contrast, a widely studied nusA deletion proposed to compromise Rho-dependent termination had no effect on antisense or sense Rho-dependent terminators in vivo. Global colocalization of the histone-like nucleoid-structuring protein (H-NS) with Rho-dependent terminators and genetic interactions between hns and rho suggest that H-NS aids Rho in suppression of antisense transcription. The combined actions of Rho, NusG, and H-NS appear to be analogous to the Sen1–Nrd1–Nab3 and nucleosome systems that suppress antisense transcription in eukaryotes.
In Vivo Two-Photon Imaging of Neurons and Glia in the Mouse Spinal Cord
Authors: Steffens Heinz , Nadrigny Fabien , Kirchhoff Frank
Published: December 2012

Two-photon imaging of the nervous system is now used extensively for visualizing brain dynamics and signal activities. To date, scientists have focused on the analysis either of gray matter forebrain structures, such as the cortex and cerebellum, or they have investigated muscle innervation of peripheral nerves. The spinal cord is an ideal structure to use for imaging central nervous system white matter. The dorsal columns formed by myelinated sensory axons are located directly at the surface of the spinal cord underneath the pia mater. This protocol describes a method for imaging neuronal fibers and neighboring glial cells in transgenic mice using cell type-specific fluorescent protein expression and two-photon laser-scanning microscopy (2pLSM). Depending on how the mice are prepared, single imaging can be performed, or the spinal cord can be imaged repetitively over multiple days, with time for the mouse to recover between imaging sessions.
Selective Precipitation of Large RNAs
Authors: Nilsen Timothy W.
Published: December 2012

For reasons that are somewhat mysterious, “large” RNAs ≥100 nucleotides long can be selectively separated from small RNAs <100 nucleotides long by precipitation with either LiCl or PEG/NaCl. These methods are very straightforward, and are valuable for enriching for very small RNAs (i.e., miRNAs) in unprecipitated material while retaining all other RNAs in the precipitate.
Measuring Intrinsic Optical Signals from Mammalian Nerve Terminals
Authors: Salzberg Brian M. , Muschol Martin , Kosterin Paul , Obaid Ana Lia
Published: December 2012

Intrinsic optical changes (light scattering signals) occur in mammalian nerve terminals during and immediately following the arrival of the action potential. In the neurohypophysis (posterior pituitary gland), the action potential is coupled to calcium-mediated secretion of the neuropeptides oxytocin and vasopressin. This excitation–secretion coupling is intimately related to extremely rapid changes in light scattering. These optical signals provide a millisecond–time-resolved monitor of events in the terminals that follow the arrival of the action potential and the entry of calcium. Light scattering procedures are designed to measure intrinsic optical signals from mammalian nerve terminals. In practice, these signals are remarkably simple to record from any of the mammalian neurohypophyses that have been studied. To date, this approach has been used successfully in mouse, rat, and guinea pig. This protocol provides instrumentation requirements and a method for preparation of the neurohypophysis so that intrinsic optical signals can be measured from nerve terminals. It also includes a discussion of the interpretation of the signals that are obtained.
Pancreatic Tumor Preparation in Mice
Authors: Jain Rakesh K. , Munn Lance L. , Fukumura Dai
Published: December 2012

Pancreatic cancer has a poor prognosis, and treatment strategies conducted from preclinical research have not succeeded in extending a patient's survival appreciably. This protocol describes how to prepare an abdominal window in mice. This allows both direct intravital microscopy and chronic observation during pancreas tumor growth and the response to treatment.
Vertebrate herbivore‐induced changes in plants and soils: linkages to ecosystem functioning in a semi‐arid steppe
Authors: Chen Dima , Zheng Shuxia , Shan Yumei , Taube Friedhelm , Bai Yongfei
Published: December 2012

Large grazing herbivores have been reported to determine the structure and function of grassland ecosystems. However, the ecological linkages between structure and functioning components have yet been thoroughly explored.

Here, we test the hypothesis of the impact of grazing on soil nematode community (e.g. structure and composition) and linkages to ecosystem functioning (e.g. soil N mineralization and ANPP) via changes in pathways of plant community, soil nutrients and soil environment using a field experiment maintained for 5 years with seven levels of grazing intensity in the Inner Mongolian grassland.

A structural equation model (SEM) with nematode abundances as response variables showed that plant‐feeding and fungal‐feeding nematodes were driven by changes in the plant community, and bacterial‐feeding nematodes were affected by soil abiotic nutrients and environment, while omnivorous + carnivorous nematodes were altered by soil environment and bacterial‐feeding nematodes. This indicates that the top‐down control by grazing leads to bottom‐up control in the soil food web.

We found that grazing affected the ecosystem functioning via different pathways. Grazing effects soil N mineralization by changing plant community, soil nutrients, soil environment and nematodes community structure, while it affects ANPP by altering soil N mineralization and soil environment.

Our findings could provide a better understanding of the responses of plants and soils to grazing and the linkages between structure and functioning of above‐ground and below‐ground in the semi‐arid steppe.
Gauging recovery of zooplankton from historical acid and metal contamination: the influence of temporal changes in restoration targets
Authors: Palmer Michelle E. , Keller Wendel (Bill) , Yan Norman D.
Published: December 2012

Clearly defined restoration targets are necessary to judge the effectiveness of management actions in restoring damaged ecosystems. However, the identification of appropriate targets is difficult in a rapidly changing world. Historical reference conditions commonly provide recovery targets, but they may not be appropriate if present‐day environments have shifted in response to regional or global drivers. Such shifts may need to be incorporated into restoration targets to avoid erroneous conclusions about the recovery of ecosystems damaged by localized stressors. No previous study has examined whether the selection of historical vs. present‐day reference conditions alters judgments of the recovery of historically damaged ecosystems.

We examined 35‐year trends in the zooplankton communities of four lakes polluted by smelter emissions in Sudbury, Ontario, Canada. Recovery was assessed by comparing the Sudbury lakes to both historical (1983–1984) and present‐day (2004–2006) conditions in a set of minimally impacted reference lakes in south‐central Ontario.

Sudbury zooplankton communities improved substantially over time when compared with both the historical and present‐day recovery targets. However, recovery occurred later, and improvements differed quantitatively when judged against the present‐day vs. historical targets. These differences were attributable to regional shifts in zooplankton communities that happened after the historical sampling period but were reflected in the present‐day data.

Species richness in two Sudbury lakes met recovery targets and communities in all four lakes became more similar to those in the reference lakes. However, the continued absence of many daphniids, cyclopoids and large calanoids indicated that the lakes had not fully recovered and further monitoring is needed.

Synthesis and applications. Our results show that the choice of reference condition can alter recovery assessments. This finding emphasizes the importance of establishing clearly defined restoration goals to ensure appropriate choice of reference conditions. Restoration is unlikely to be judged as successful if an historical reference point is used to guide management actions meant to restore an ecosystem to present‐day regional conditions.
Tips and tricks for the assembly of a Corynebacterium pseudotuberculosis genome using a semiconductor sequencer
Authors: Ramos Rommel Thiago Jucá , Carneiro Adriana Ribeiro , Soares Siomar de Castro , Santos Anderson Rodrigues dos , Almeida Sintia , Guimarães Luis , Figueira Flávia , Barbosa Eudes , Tauch Andreas , Azevedo Vasco , Silva Artur
Published: December 2012

New sequencing platforms have enabled rapid decoding of complete prokaryotic genomes at relatively low cost. The Ion Torrent platform is an example of these technologies, characterized by lower coverage, generating challenges for the genome assembly. One particular problem is the lack of genomes that enable reference‐based assembly, such as the one used in the present study, Corynebacterium pseudotuberculosis biovar equi, which causes high economic losses in the US equine industry. The quality treatment strategy incorporated into the assembly pipeline enabled a 16‐fold greater use of the sequencing data obtained compared with traditional quality filter approaches. Data preprocessing prior to the de novo assembly enabled the use of known methodologies in the next‐generation sequencing data assembly. Moreover, manual curation was proved to be essential for ensuring a quality assembly, which was validated by comparative genomics with other species of the genus Corynebacterium. The present study presents a modus operandi that enables a greater and better use of data obtained from semiconductor sequencing for obtaining the complete genome from a prokaryotic microorganism, C. pseudotuberculosis, which is not a traditional biological model such as Escherichia coli.
Bio‐based production of organic acids with Corynebacterium glutamicum
Authors: Wieschalka Stefan , Blombach Bastian , Bott Michael , Eikmanns Bernhard J.
Published: December 2012

The shortage of oil resources, the steadily rising oil prices and the impact of its use on the environment evokes an increasing political, industrial and technical interest for development of safe and efficient processes for the production of chemicals from renewable biomass. Thus, microbial fermentation of renewable feedstocks found its way in white biotechnology, complementing more and more traditional crude oil‐based chemical processes. Rational strain design of appropriate microorganisms has become possible due to steadily increasing knowledge on metabolism and pathway regulation of industrially relevant organisms and, aside from process engineering and optimization, has an outstanding impact on improving the performance of such hosts. Corynebacterium glutamicum is well known as workhorse for the industrial production of numerous amino acids. However, recent studies also explored the usefulness of this organism for the production of several organic acids and great efforts have been made for improvement of the performance. This review summarizes the current knowledge and recent achievements on metabolic engineering approaches to tailor C. glutamicum for the bio‐based production of organic acids. We focus here on the fermentative production of pyruvate, l‐ and d‐lactate, 2‐ketoisovalerate, 2‐ketoglutarate, and succinate. These organic acids represent a class of compounds with manifold application ranges, e.g. in pharmaceutical and cosmetics industry, as food additives, and economically very interesting, as precursors for a variety of bulk chemicals and commercially important polymers.
The methylation landscape of tumour metastasis
Authors: Cock‐Rada Alicia , Weitzman Jonathan B.
Published: December 2012

The metastatic cascade which leads to the death of cancer patients results from a multi‐step process of tumour progression caused by genetic and epigenetic alterations in key regulatory molecules. It is, therefore, crucial to improve our understanding of the regulation of genes controlling the metastatic process to identify predictive biomarkers and to develop more effective therapies to treat advanced disease. The study of epigenetic mechanisms of gene regulation offers a novel approach for innovative diagnosis and treatment of cancer patients. Recent discoveries provide compelling evidence that the methylation landscape (changes in both DNA methylation and histone post‐translational modifications) is profoundly altered in cancer cells and contributes to the altered expression of genes regulating tumour phenotypes. However, the impact of methylation events specifically on the advanced metastatic process is poorly understood compared with the initial oncogenic events. Moreover, the characterisation of a large number of histone‐modifying enzymes has revealed their active roles in cancer progression, via the regulation of specific target genes controlling different metastatic phenotypes. Here, we discuss two main methylating events (DNA methylation and histone‐tail methylation) involved in oncogenesis and metastasis formation. The potential reversibility of these molecular events makes them promising biomarkers of metastatic potential and potential therapeutic targets.
α‐Substitution Effects on the Ease of S→N‐Acyl Transfer in Aminothioesters
Authors: El‐Gendy Bahaa El‐Dien M. , Ghazvini Zadeh Ebrahim H. , Sotuyo Ania C. , Pillai Girinath G. , Katritzky Alan R.
Published: December 2012

In S‐acylcysteines and homocysteines, the efficacy and rate of S→N‐acyl transfer (5 and 6 cyclic TSs) vary with the size of S‐acyl group. Conformational and quantum chemical calculations indicate that the spatial distance, b(N‐C), between the terminal amine and the thioester carbon is shortened by α‐C(O)X (X = OH, OMe, NH2) substituents.
The role of belataceptin transplantation: results and implications of clinical trials in the context of other new biological immunosuppressant agents
Authors: Heemann Uwe , Viklicky Ondrej
Published: December 2012

Although conventional immunosuppressive agents such as calcineurin inhibitors, have substantially reduced the risk of acute rejection, they have had less impact on the long‐term survival. This is likely to be related to the adverse effects of such agents in terms of impaired renal function, hypertension, and dyslipidemia. These pitfalls of the currently available agents stimulated the research for biologic agents. Several biologic agents are now in development and hold promise for improved long‐term outcomes in renal transplant recipients, particularly in those who receive sub‐optimal organs. This article gives an overview of these new biological agents with particular emphasis on belatacept and their possible impact on short‐ and long‐term outcomes, notably on marginal organs.
The sexually dimorphic on the Y‐chromosome gene (sdY) is a conserved male‐specific Y‐chromosome sequence in many salmonids
Authors: Yano Ayaka , Nicol Barbara , Jouanno Elodie , Quillet Edwige , Fostier Alexis , Guyomard René , Guiguen Yann
Published: December 2012

All salmonid species investigated to date have been characterized with a male heterogametic sex‐determination system. However, as these species do not share any Y‐chromosome conserved synteny, there remains a debate on whether they share a common master sex‐determining gene. In this study, we investigated the extent of conservation and evolution of the rainbow trout (Oncorhynchus mykiss) master sex‐determining gene, sdY (sexually dimorphic on the Y‐chromosome), in 15 different species of salmonids. We found that the sdY sequence is highly conserved in all salmonids and that sdY is a male‐specific Y‐chromosome gene in the majority of these species. These findings demonstrate that most salmonids share a conserved sex‐determining locus and also strongly suggest that sdY may be this conserved master sex‐determining gene. However, in two whitefish species (subfamily Coregoninae), sdY was found both in males and females, suggesting that alternative sex‐determination systems may have also evolved in this family. Based on the wide conservation of sdY as a male‐specific Y‐chromosome gene, efficient and easy molecular sexing techniques can now be developed that will be of great interest for studying these economically and environmentally important species.
The English ‘Proto‐Gentry’ in the Reigns of Edward I and Edward II
Authors: Simpkin David
Published: December 2012

Recent research suggests that the 13th and 14th centuries were key to the development and formation of gentry identity in later medieval England. Notions of gentility certainly existed in this period; yet the term ‘gentry’ as used by modern historians is a construct and the divergent historiographical traditions within gentry studies make it difficult to ascertain with any certitude who the gentry were, how they perceived themselves and the world around them, and their influence on and interaction with their surroundings. In short, there is little agreement on the essence of gentry identity and the stages by which that identity became more precisely defined. In this paper an attempt is made to survey the main schools of thought in gentry studies over the last two to three decades, the extent to which these schools of thought diverge or intersect, and where this leaves gentry studies going forward. The focus is primarily on the reigns of Edward I and Edward II, a time when according to the researches of Professor Peter Coss, a ‘proto‐gentry’ began to materialise in England.
Effect of koji fermentation on generation of volatile compounds in soy sauce production
Authors: Feng Yunzi , Cui Chun , Zhao Haifeng , Gao Xianli , Zhao Mouming , Sun Weizheng
Published: December 2012

The generation of aroma compounds and the changes in sensory characteristics through the soy sauce koji fermentation were investigated to evaluate the crucial impact of the koji fermentation on soy sauce aroma. The sensory analysis showed a marked increase in ‘musty’ and ‘soy sauce‐like’ odours, whereas the beany attribute decreased significantly during koji fermentation. Aldehydes and alcohols were the major volatile classes present in the koji samples. Gas chromatography–olfactometry was used to identify the aroma‐active compounds in harvested koji, and the results showed that 1‐octen‐3‐ol, 3‐octanol, (E)‐2‐octenal, di‐epi‐α‐cedrene, benzeneacetaldehyde and 3‐(methylthio)‐propanal exhibited the greatest aroma intensities in harvest koji. Moreover, relative contents of (E)‐2‐octenal, benzeneacetaldehyde, 3‐(methylthio)‐propanal and 2‐phenylpropenal were found to be positively related to ‘musty’ and ‘soy sauce‐like’ odours. Results from principal component analysis showed that the growth and sporulation of Aspergillus oryzae had the important impacts on the volatile evolution.
Effect of the dry ice maceration and oak cask fermentation on colour parameters and sensorial evaluation of Tempranillo wines
Authors: Puertas Belén , Jiménez María J. , Cantos‐Villar Emma , Piñeiro Zulema
Published: December 2012

The impact of dry ice maceration (DIM) and oak cask fermentation (OCF) on characteristics of Tempranillo wines elaborated in a warm climate has been studied as an alternative procedure to traditional red winemaking (CT) to obtain highly coloured wines. Oenological and colour parameters were measured to determine the influence of these techniques on wines along the winemaking process. DIM and OCF techniques were found significantly different to CT for colour intensity and percentage of blue. Moreover, both induced easily perceptible changes in CIELAB coordinates (lower L*, higher a* and values) than CT and also affect main wine's sensory attributes (e.g. increased polyphenols extraction in DIM and to a lesser extent OCF, and therefore produced wines with higher colour than CT). Although differences tend to decrease with ageing, these practices seem feasible alternatives to improve quality characteristics of young red wines from grapes grown in warm climates.
A CLEAR AND PRESENT MINORITY: HETEROGENEITY IN THE SOURCE OF ENDOWMENTS AND THE PROVISION OF PUBLIC GOODS
Authors: OXOBY ROBERT J. , SPRAGGON JOHN
Published: December 2012

We conduct public goods experiments in which participant groups are heterogeneous in regards to the source of their endowments. We find that this dimension of heterogeneity significantly reduces contributions to the public good, yielding strong support for the Nash prediction of minimal contributions. These minimal contributions arise in environments in which there exists a clear minority in terms of source of endowments. We discuss these results in light of current research on the influence of heterogeneous populations on public goods provision and redistributive policies. (JEL C9, D63, H4, J15)
DIFFERENTIATED ASSETS: AN EXPERIMENTAL STUDY ON BUBBLES
Authors: CHAN KENNETH S. , LEI VIVIAN , VESELY FILIP
Published: December 2012

In this paper, we study if and how having two differentiated assets affects bubble formation. We consider differences in assets' intrinsic characteristics as well as trading regulations that help differentiate two otherwise identical assets. We find that, compared to trading regulations, differences in assets' intrinsic characteristics encourage more arbitrage across assets and thus help reduce mispricing significantly. We also find that short‐term speculation does not depend on how assets or markets are being differentiated. As a result, short‐term speculation cannot be used to explain why bubbles are smaller when two assets are intrinsically different than when they are not. (JELC91, F34)
TRADE COSTS AND TRADE COMPOSITION
Authors: MILNER CHRIS , McGOWAN DANNY
Published: December 2012

In this paper, we investigate whether countries' trade costs act like other national endowments by affecting the composition of countries' exports. Using an econometric approach that controls for endogeneity by accounting for potentially relevant omitted variables, we find strong evidence for a sample of 37 industrialized and transition countries that national trade costs systematically affect the composition of trade and can be viewed therefore as a source of comparative advantage. Industries located in countries with low trade costs capture significantly higher shares of world exports, where this effect is stronger in trade cost intensive industries. (JEL F11, F14)
The Capital Asset Pricing Model (CAPM): The History of a Failed Revolutionary Idea in Finance?
Authors: Dempsey Mike
Published: December 2012

The capital asset pricing model (CAPM) states that assets are priced commensurate with a trade‐off between undiversifiable risk and expectations of return. The model underpins the status of academic finance, as well as the belief that asset pricing is an appropriate subject for economic study. Notwithstanding, our findings imply that in adhering to the CAPM we are choosing to encounter the market on our own terms of rationality, rather than the market's.