bluuebunny/crossref_metadata_2025 huggingface dataset:
No trend in volume of Antarctic snowmelt
Authors: Balcerak Ernie
Published: March 2012

A new study that measured Antarctic snowmelt volume found no significant trend over the past 31 years. Kuipers Munneke et al. used satellite microwave sensors, which can detect meltwater, combined with a regional climate model that includes snow physics to determine the Antarctic snowmelt volume for the period from 1979 to 2010. They found a mean continent‐wide meltwater volume of about 90 gigatons per year. Although they observed large interannual variability, they found no significant trend in continent‐ wide or regional meltwater volume over the study period. Although almost all of the snow that melts in Antarctica refreezes and therefore does not contribute directly to sea level rise, it is useful to quantify snowmelt because meltwater can contribute to the weakening of ice shelves. (Geophysical Research Letters, doi:10.1029/2011GL050207, 2012)
Spontaneous formation and degradation of pool‐riffle morphology and sediment sorting using a simple fractional transport model
Authors: de Almeida Gustavo Adolfo Mazza , Rodríguez José F.
Published: March 2012

Many gravel bed streams have a typical bed morphology consisting of pool‐riffle sequences, which provides important habitat diversity both in terms of flow and substrate. A complete explanation of pool‐riffle genesis and self‐maintenance remains elusive and, despite advances in understanding the effects of flow spatial and temporal variability, the key sediment processes have been only marginally explored. Here we use a 1D unsteady multi‐fraction morphodynamic model to explain the formation and degradation of pool‐riffle sequences. Using a 1‐year time series of measured flows below bankfull on a stream in which we have removed initial bedforms and sediment sorting our model spontaneously generates pools with finer substrate at narrow sections and riffles with coarser sediment at wider sections, closely resembling the natural bed morphology. Additional experiments show that under our modelling assumptions a variable flow regime is fundamental for development and self‐maintenance of the longitudinal grain sorting characteristic of pool‐riffle sequences, which could not be obtained or maintained with discharges held constant over relatively long periods.
The Nedd4-like ubiquitin E3 ligases target angiomotin/p130 to ubiquitin-dependent degradation
Authors: Wang Chenji , An Jian , Zhang Pingzhao , Xu Chen , Gao Kun , Wu Di , Wang Dejie , Yu Hongxiu , Liu Jun O. , Yu Long
Published: March 2012

AMOT (angiomotin) is a membrane-associated protein that is expressed in ECs (endothelial cells) and controls migration, TJ (tight junction) formation, cell polarity and angiogenesis. Recent studies have revealed that AMOT and two AMOT-like proteins, AMOTL1 and AMOTL2, play critical roles in the Hippo pathway by regulating the subcellular localization of the co-activators YAP (Yes-associated protein) and TAZ (transcriptional co-activator with PDZ-binding motif). However, it has been unclear how AMOT is regulated. In the present study, we report that AMOT undergoes proteasomal degradation. We identify three members of Nedd4 (neural-precursor-cell-expressed developmentally down-regulated)-like ubiquitin E3 ligases, Nedd4, Nedd4-2 and Itch, as the ubiquitin E3 ligases for the long isoform of AMOT, AMOT/p130. We demonstrate that Nedd4, Nedd4-2 and Itch mediate poly-ubiquitination of AMOT/p130 in vivo. Overexpression of Nedd4, Nedd4-2 or Itch leads to AMOT/p130 proteasomal degradation. Knockdown of Nedd4, Nedd4-2 and Itch causes an accumulation of steady-state level of AMOT/p130. We also show that three L/P-PXY motifs of AMOT/p130 and the WW domains of Nedd4 mediate their interaction. Furthermore, Nedd4-like ubiquitin E3 ligases might compete with YAP for the binding to AMOT/p130, and subsequently targeting AMOT/p130 for ubiquitin-dependent degradation. Together, these observations reveal a novel post-translational regulatory mechanism of AMOT/p130.
The Bcl-2 proteins Noxa and Bcl-xL co-ordinately regulate oxidative stress-induced apoptosis
Authors: Eno Colins O. , Zhao Guoping , Olberding Kristen E. , Li Chi
Published: March 2012

Because the detailed molecular mechanisms by which oxidative stress induces apoptosis are not completely known, we investigated how the complex Bcl-2 protein network might regulate oxidative stress-induced apoptosis. Using MEFs (mouse embryonic fibroblasts), we found that the endogenous anti-apoptotic Bcl-2 protein Bcl-xL prevented apoptosis initiated by H2O2. The BH3 (Bcl-2 homology 3)-only Bcl-2 protein Noxa was required for H2O2-induced cell death and was the single BH3-only Bcl-2 protein whose pro-apoptotic activity was completely antagonized by endogenous Bcl-xL. Upon H2O2 treatment, Noxa mRNA displayed the greatest increase among BH3-only Bcl-2 proteins. Expression levels of the anti-apoptotic Bcl-2 protein Mcl-1 (myeloid cell leukaemia sequence 1), the primary binding target of Noxa, were reduced in H2O2-treated cells in a Noxa-dependent manner, and Mcl-1 overexpression was able to prevent H2O2-induced cell death in Bcl-xL-deficient MEF cells. Importantly, reduction of the expression of both Mcl-1 and Bcl-xL caused spontaneous cell death. These studies reveal a signalling pathway in which H2O2 activates Noxa, leading to a decrease in Mcl-1 and subsequent cell death in the absence of Bcl-xL expression. The results of the present study indicate that both anti- and pro-apoptotic Bcl-2 proteins co-operate to regulate oxidative stress-induced apoptosis.
Probing the magnetization reversal in epitaxial Fe/IrMn exchange biased bilayers using angle-dependent anisotropic magnetoresistance
Authors: Zhang Wei , Krishnan Kannan M.
Published: March 2012

We investigated the detailed magnetotransport properties of epitaxial Fe/IrMn exchange biased bilayers by angle-dependent anisotropic magnetoresistance measurements over a wide temperature range. Irreversible resistance jumps and smooth transitions are observed when measuring along different angles with respect to the bias at certain temperatures. The angular dependence of the switching fields shows good agreement with a domain wall (DW) nucleation model. The exchange bias, the induced uniaxial anisotropy, and the intrinsic 90° DW nucleation energy are further extracted from the angle-dependent measurements. A linear temperature dependence is observed for both the exchange bias and the induced uniaxial anisotropy, while the intrinsic 90° DW nucleation energy is independent of the temperature.
Tunable positive magnetoresistance effect of Co-doped amorphous carbon films
Authors: Jiang Y. C. , Wu Z. P. , Bao W. , Xu S. J. , Gao J.
Published: March 2012

Co-doped amorphous carbon (a-C:Co) films were deposited on n-type Si substrates by pulsed-laser deposition method. A positive magnetoresistance (PMR) effect has been observed after Co doped into a-C films. Such a PMR is tuned by the bias voltage and reaches a peak at a particular voltage, as observed from the Current-voltage relations of the a-C:Co/Si junctions at various magnetic fields. MR-H characteristics were further studied at the temperatures of 65 K, which showed that under the reverse electric field the a-C:Co/Si junctions had a colossal PMR (over 100%). Raman spectra results demonstrate that Co doping favors the formation of graphitic sp2 sites. The mechanism of the PMR effect is attributed to the interactions between the applied magnetic field and Co ions, which leads to the transition from sp2 sites to sp3 sites and increase the resistance.
Solution to the problem of E-cored coil above a layered half-space using the method of truncated region eigenfunction expansion
Authors: Sakkaki Fahimeh , Bayani Hossein
Published: March 2012

In eddy current non-destructive testing, using ferrite cores with different shapes produce interesting and very important predictions on locating underneath cracks, corrosions and flaws in conductive layers. This paper describes a method of calculating magnetic vector potential for an E-cored eddy current probe above a layered half space. The coil impedance variation with frequency and eddy currents are determined. The results of the calculations are in very good agreement with results from COMSOL.
Large reversible magnetocaloric effect in TmTiO3 single crystal
Authors: Su Yantao , Sui Yu , Cheng Jinguang , Wang Xianjie , Wang Yang , Liu Pan , Tang Jinke
Published: March 2012

The magnetic properties and magnetocaloric effect (MCE) of TmTiO3 single crystal were studied by magnetization and heat capacity measurements. A large reversible MCE was observed at the Curie temperature TC of 65 K, which is related to a second-order magnetic transition from paramagnetic to ferrimagnetic state. The values of maximum magnetic entropy change can reach 7.2 and 13.5 J kg−1 K−1 for a field change of 2 and 5 T, respectively, with no obvious hysteresis loss in the vicinity of the Curie temperature. The corresponding maximum adiabatic temperature changes are found to be 3.5 and 6.8 K. The magnetic transition and the origin of large MCE in TmTiO3 single crystal are discussed.
Control of magnetic properties of MnBi and MnBiCu thin films by Kr+ ion irradiation
Authors: Xu Qianqian , Kanbara Ryutarou , Kato Takeshi , Iwata Satoshi , Tsunashima Shigeru
Published: March 2012

Mn52Bi48 (15 nm) and Mn54Bi24Cu21 (15 nm) thin films were prepared by the magnetron sputtering and vacuum annealing at 350 °C, and the variations of their structures and magnetic properties with 30 keV Kr+ ion irradiation were studied. The MnBi and MnBiCu films exhibited saturation magnetizations Ms of 180 emu/cc and 210 emu/cc, the coercivities Hc of 10 kOe and 3.4 kOe, respectively. The Ms and Hc of the MnBi abruptly vanished by the irradiation of ion dose at 3 × 1014 ions/cm2, while those of the MnBiCu film gradually decreased with increasing the ion dose and became zero at 5 × 1013 ions/cm2. The different trend on the ion irradiation between MnBi and MnBiCu films is understood by the surface structure of the film, i.e., the MnBi has convex islands on its surface, which protect the underneath NiAs-type MnBi from the irradiation, while the MnBiCu has rather flat surface, and its crystal structure was uniformly modified by the irradiation. From the surface flatness and the uniformity of the MnBiCu film, as well as the low annealing temperature of 350 °C, it was concluded that the MnBiCu film is one of the attractive materials for high-density ion irradiation bit patterned media.
Magnetic and charge ordering properties of Bi0.6-x(RE)xCa0.4MnO3 (0.0 ≤ x ≤ 0.6) perovskite manganites
Authors: Yadav Kamlesh , Singh M. P. , Singh H. K. , Razavi F. S. , Varma G. D.
Published: March 2012

In this work, we studied structural, magnetic, and charge ordering properties of polycrystalline Bi0.6−x (RE)x Ca0.4MnO3 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) samples, synthesized via solid state reaction route and by taking RE = La, Pr, and Nd, separately. The temperature dependence magnetization measurement reveals that the x = 0.0 compound (BCMO) exhibits a charge ordered (CO) and antiferromagnetic (AFM) phase with the charge ordering temperature (TCO) ∼289 K and the antiferromagnetic ordering temperature (TN) ∼136 K. Only a small fraction of La-dopant in BCMO is sufficient to destroy the CO completely, whereas a large concentration of La (viz., x = 0.2 to x = 0.6) promotes ultimately a paramagnetic to ferromagnetic (PM-FM) transition, and the PM-FM transition temperature (TC) decreases progressively from 241 K to 203 K as x increases from 0.2 to 0.5. In contrast, systematic substitution of Pr or Nd at Bi site induces an intriguing interplay between the charge ordering and antiferromagnetism. Our results demonstrate that the value of TCO decreases with increasing value of “x” and the value of TN increases sharply at both the extremes; however, it remains nearly constant from x = 0.2 to 0.4. In our samples, a glassy magnetic states are also observed at far below the TN.
Influence of interface termination on the magneto-Seebeck effect in MgO based tunnel junctions
Authors: Czerner Michael , Heiliger Christian
Published: March 2012

On an ab initio level, we investigate the recently observed magneto-Seebeck effect in MgO based tunnel junctions. In particular, we considered ordered CoFe alloys as lead material. Next to the MgO barrier, there are different possible terminations of the CoFe alloy due to the assumed ordered alloy. These results show a strong influence of the termination on the temperature dependence of the magneto-Seebeck effect. In addition, we use a simple model to account for randomly ordered alloys. We propose, that by a controlled treatment of the CoFe/MgO interface the magneto-Seebeck effect can be tuned experimentally.
Oxygen-vacancy effect on structural, magnetic, and ferroelectric properties in multiferroic YMnO3 single crystals
Authors: Chen D. P. , Du Y. , Wang X. L. , Cheng Z. X. , Dou S. X. , Lin Z. W. , Zhu J. G. , Xu B.
Published: March 2012

We have investigated the structural, magnetic, and ferroelectric properties of magnetically frustrated multiferroic YMnO3 single crystals. The ferroelectric domain structures of YMnO3 samples were studied by piezoresponse force microscopy. Instead of domain vortex structure in stoichiometric crystals, YMnO3−δ exhibits a random domain configuration with straight domain walls. In magnetic measurements, the YMnO3−δ crystal shows typical antiferromagnetic behavior with higher Néel temperature and lower magnetization compared to the stoichiometric sample. The ordered oxygen vacancies dominate multiferroicity through tailoring the domain wall structure.
de Haas–van Alphen effect and Fermi surface properties in rare earth and actinide compounds (Review Article)
Authors: Ōnuki Yoshichika , Settai Rikio
Published: March 2012

Fermi surface properties in rare earth (R) and actinide (An) compounds of RX3 (X: Al, Ga, In, Si, Ge, Sn, Pb), AnX3, RTIn5 (T: transition metal), and AnTGa5 are clarified as a function of the number of valence electrons. The electronic state can be changed by applying pressure and magnetic field. A change of Fermi surface properties associated with the metamagnetic behavior and the quantum critical point is also clarified precisely, together with the split Fermi surfaces in the non-centrosymmetric crystal structure, and the de Haas–van Alphen oscillations in the superconducting mixed state. In the quantum critical point region, the conduction electrons, or quasi-particles, are of an f-electron character, with heavy effective masses of 10–100 m0 (m0 is the rest mass of an electron) and condense into the unconventional (anisotropic) superconducting state.
Polaritons in the ferromagnetic material TbMnO3 at a boundary with a metal in a magnetic field
Authors: Chupis I. E.
Published: March 2012

The spectrum of surface polaritons in an antiferromagnetic material with a spiral magnetic structure and spin-induced electrical polarization at a boundary with a metal in a magnetic field is analyzed. The manganite TbMnO3 in its ferroelectromagnetic and paraelectric phases is considered as an example. The resulting spectrum is characterized by a strong nonreciprocity and depends substantially on the directions of the magnetic field and of the spontaneous electrical polarization, as well as on the ratio of these quantities. Estimates for TbMnO3 show that a strong nonreciprocity, such that polaritons with a given frequency propagate only in one direction, can be created by a magnetic field of a few kOe.
Effect of plastic deformation on the low-temperature minimum of the thermal emf of copper
Authors: Svetlov V. N.
Published: March 2012

The effect of plastic deformation on the thermal emf and electrical resistance of polycrystalline copper is studied at low temperatures. Primary attention is devoted to the minimum in the thermal emf near 15 K and the changes in it during plastic deformation on the order of and less than 100%. These studies offer the prospect of deeper understanding of the mechanisms of electron scattering in metals with defects.
Quasi first-principles Monte Carlo modeling of energy dissipation by low-energy electron beams in multi-walled carbon nanotube materials
Authors: Emfietzoglou Dimitris , Kyriakou Ioanna , Garcia-Molina Rafael , Abril Isabel , Kostarelos Kostas
Published: March 2012

The energy dissipation pattern of low-energy electron beams (0.3–30 keV) in multi-walled carbon nanotube (MWCNT) materials is studied by Monte Carlo simulation taking into account secondary-electron cascade generation. A quasi first-principles discrete-energy-loss model deduced from a dielectric response function description of electronic excitations in MWCNTs is employed whereby both single-particle and plasmon excitations are included in a unified and self-consistent manner. Our simulations provide practical analytical functions for computing depth-dose curves and charged-carrier generation volumes in MWCNT materials under low-energy electron beam irradiation.
Valence band structure in boron-zinc oxide films characterized by secondary electron emission
Authors: Uhm Han S. , Choi Joon H. , Yoo Ha J. , Kwon Gi C. , Choi Eun H.
Published: March 2012

Properties of the valence band structure in boron-zinc oxide (BZO) films were investigated using the secondary electron emission due to the Auger neutralization of helium ions, with respect to the application of BZO films to the development of solar cells, in which the conductivity of the BZO films plays a critical role in improving cell performance. The characteristic energy ɛ0 corresponding to the peak density of states in the valence band showed that BZO film prepared with a 3000 SCCM B2H6 gas flow rate (SCCM denotes cubic centimeters per minute at standard temperature and pressure) had a shallow characteristic energy ɛ0 = 5 eV, whereas film without boron doping had a deep characteristic energy ɛ0 = 8.2 eV, suggesting that a high concentration of boron impurity in BZO films might enhance the transition of electrons and holes through the bandgap from the valence to the conduction band in zinc oxide crystals, thereby improving the conductivity of the film. The measurement method developed here demonstrates that the secondary electron emission is very useful in the determination of the band structure in various synthetic films.
Anisotropic capillary instability of silicon nanostructures under hydrogen anneal
Authors: Barwicz T. , Cohen G. M. , Reuter K. B. , Bangsaruntip S. , Sleight J. W.
Published: March 2012

Anneal in reduced pressure hydrogen ambient is known to induce morphological changes in silicon microstructures via markedly increased surface self-diffusivity on exposed silicon surfaces. Here, we investigate the capillary instability of silicon nanostructures under hydrogen anneal. We demonstrate that a surface diffusion mask can significantly improve stability by isolating vulnerable segments from large mass reservoirs. In addition, we find that Plateau-Rayleigh instability shows strong crystallographic dependence, which is explained by the surface energy anisotropy of silicon. We observe that nanowires are the least stable when their axial orientation corresponds to 〈100〉 and are increasingly stable for 〈111〉, 〈112〉, and 〈110〉.
Robust generation of bright two-color entangled optical beams from a phase-insensitive optical parametric amplifier
Authors: Guo Xiaomin , Zhao Junjun , Li Yongmin
Published: March 2012

Bright two-color continuous variable (CV) entangled optical beams at 0.8 and 1.5 μm are generated by utilizing a phase-insensitive optical parametric amplifier with only 1.5 μm signal field injected. Without locking the relative phase between the signal and pump fields, the amplitude quadrature difference squeezing of 3.30 dB and phase quadrature sum squeezing of 3.35 dB are observed, which satisfy the entanglement criterion. The demonstrated scheme here eliminates the necessity of precise phase control between the signal and pump fields and enables robust generation of two-color CV entangled states.
Bi-induced p-type conductivity in nominally undoped Ga(AsBi)
Authors: Pettinari G. , Patanè A. , Polimeni A. , Capizzi M. , Lu Xianfeng , Tiedje T.
Published: March 2012

We report p-type conductivity in nominally undoped GaAs1–xBix epilayers for a wide range of Bi-concentrations (0.6% ≤ x ≤ 10.6%). The counterintuitive increase of the conductivity with increasing x is paralleled by an increase in the density of free holes by more than three orders of magnitude in the investigated Bi-concentration range. The p-type conductivity results from holes thermally excited from Bi-induced acceptor levels lying at 26.8 meV above the valence band edge of GaAs1−xBix with concentration up to 2.4 × 1017 cm−3 at x = 10.6%.
Nano-lithography free formation of high density Ge-on-insulator network for epitaxial template
Authors: Yokoyama Hiroyuki , Toko Kaoru , Sadoh Taizoh , Miyao Masanobu
Published: March 2012

High-quality Ge-on-insulator (GOI) structures are essential for integrating multi-functional devices onto the Si-platform. We develop the nano-lithography free method for single-crystalline GOI networks by combining partial Ge evaporation and rapid-melting growth techniques. This realizes chip size GOI with high Ge coverage fractions (>75%), which is crisscrossed with nano-spacing (∼100 nm width). Over-epitaxy of Ge on the GOI network is also examined, which achieves single-crystalline GOI uniform-plane by covering the nano-spacing. This proves the validity of high-density GOI networks as the epitaxial template. This method will facilitate the heterogeneous integration of Ge, III-V semiconductors, and magnetic materials on the Si-platform.
Women’s knowledge, attitudes and practice about breast cancer screening in the region of Monastir (Tunisia)
Authors: El Mhamdi Sana , Bouanene Ines , Mhirsi Amel , Sriha Asma , Ben Salem Kamel , Soltani Mohamed Soussi
Published: March 2012

Breast cancer remains a worldwide public health problem. In Tunisia, it is considered to be the primary women’s cancer and causes high morbidity and mortality. This study aimed to investigate female knowledge, attitudes and practice of breast cancer screening in the region of Monastir (Tunisia). We conducted a descriptive cross-sectional design exploring knowledge, attitudes and practices of women in the region of Monastir on breast cancer screening. The study was conducted in health centres of this region from 1 March 2009 to 30 June 2009. Data were collected via a structured questionnaire containing 15 items on demographic status, knowledge of risk factors and screening methods and attitudes towards the relevance and effectiveness of breast cancer screening. A scoring scheme was used to score women’s responses. A total of 900 women agreed to take part in the study. Their mean age was 41.6 ± 12.4 years and 64% did not exceed the primary level of education. According to the constructed scores, 92% of participants had poor knowledge of the specific risk factors for breast cancer and 63.2% had poor knowledge of the screening methods. Proper practice of breast cancer screening was observed in 14.3% of cases. Multiple logistic regression analysis showed that good knowledge of risk factors and screening methods, higher level of education and positive family history of breast cancer were independently correlated with breast cancer screening practice. This study revealed poor knowledge of breast cancer and the screening methods as well as low levels of practice of breast cancer screening among women in the region of Monastir. Results justify educational programs to raise women’s adherence to breast cancer screening programs in Tunisia.
Rapid diversification of coevolving marine
Synechococcus
and a virus
Authors: Marston Marcia F. , Pierciey Francis J. , Shepard Alicia , Gearin Gary , Qi Ji , Yandava Chandri , Schuster Stephan C. , Henn Matthew R. , Martiny Jennifer B. H.
Published: March 2012

Marine viruses impose a heavy mortality on their host bacteria, whereas at the same time the degree of viral resistance in marine bacteria appears to be high. Antagonistic coevolution—the reciprocal evolutionary change of interacting species—might reconcile these observations, if it leads to rapid and dynamic levels of viral resistance. Here we demonstrate the potential for extensive antagonistic coevolution between the ecologically important marine cyanobacterium
Synechococcus
and a lytic virus. In a 6-mo-long replicated chemostat experiment,
Synechococcus
sp. WH7803 and the virus (RIM8) underwent multiple coevolutionary cycles, leading to the rapid diversification of both host and virus. Over the course of the experiment, we detected between 4 and 13 newly evolved viral phenotypes (differing in host range) and between 4 and 11 newly evolved
Synechococcus
phenotypes (differing in viral resistance) in each chemostat. Genomic analysis of isolates identified several candidate genes in both the host and virus that might influence their interactions. Notably, none of the viral candidates were tail fiber genes, thought to be the primary determinants of host range in tailed bacteriophages, highlighting the difficulty in generalizing results from bacteriophage infecting γ-Proteobacteria. Finally, we show that pairwise virus–host coevolution may have broader community consequences; coevolution in the chemostat altered the sensitivity of
Synechoccocus
to a diverse suite of viruses, as well as the virus’ ability to infect additional
Synechococcus
strains. Our results indicate that rapid coevolution may contribute to the generation and maintenance of
Synechococcus
and virus diversity and thereby influence viral-mediated mortality of these key marine bacteria.
Agonism/antagonism switching in allosteric ensembles
Authors: Motlagh Hesam N. , Hilser Vincent J.
Published: March 2012

Ligands for several transcription factors can act as agonists under some conditions and antagonists under others. The structural and molecular bases of such effects are unknown. Previously, we demonstrated how the folding of intrinsically disordered (ID) protein sequences, in particular, and population shifts, in general, could be used to mediate allosteric coupling between different functional domains, a model that has subsequently been validated in several systems. Here it is shown that population redistribution within allosteric systems can be used as a mechanism to tune protein ensembles such that a given ligand can act as both an agonist and an antagonist. Importantly, this mechanism can be robustly encoded in the ensemble, and does not require that the interactions between the ligand and the protein differ when it is acting either as an agonist or an antagonist. Instead, the effect is due to the relative probabilities of states prior to the addition of the ligand. The ensemble view of allostery that is illuminated by these studies suggests that rather than being seen as switches with fixed responses to allosteric activation, ensembles can evolve to be “functionally pluripotent,” with the capacity to up or down regulate activity in response to a stimulus. This result not only helps to explain the prevalence of intrinsic disorder in transcription factors and other cell signaling proteins, it provides important insights about the energetic ground rules governing site-to-site communication in all allosteric systems.
The use of trees in phytoremediation.
Authors: Azzarello E. , Pandolfi C. , Pollastri S. , Masi E. , Mugnai S. , Mancuso S.
Published: March 2012

Trees can be successfully used in phytoremediation because of their ability to grow on nutrient-poor soil, deep root system, fast rate of growth, metal-resistance traits and economically viable secondary use. Thanks to these features, trees are able to stabilize, extract, degrade or volatilize soil contaminants. The paper offers a comprehensive review of the role of trees in the phytoremediation of soils contaminated by heavy metals or organic pollutants. Transgenic approaches to enhance the aforementioned processes, together with the use of chelating agents to improve the bioavailability of pollutants for plants uptake, are also reviewed and discussed.
Using selective insecticides in sustainable IPM.
Authors: Hardy M. C.
Published: March 2012

Best agricultural practices advocate the use of selective insecticides, but the practicalities of applying novel technologies can be unclear. The aim of this review is to synthesize the existing literature on novel and selective insecticides that are appropriate for use in integrated pest management (IPM) programmes, in tandem with biological control agents or as a more sustainable form of conventional chemical control of insect pests. An overview and definition of selective, non-persistent insecticides are followed by a brief introduction to recent advances in formulation chemistry and genetic engineering and nanotechnology. With the increasing popularity of 'organic' produce, it is critical that the insecticides that are allowed for use in the accredited programmes are in fact the most environmentally sensitive and have the least impact on non-target organisms. Increased emphasis on appropriate residue testing and continued monitoring of pest populations and the selection pressure for resistance are also considered. Regulatory bodies must move in a responsible manner towards approval of environmentally responsible, non-persistent insecticides that can be important components of IPM and sustainable agriculture.
Common methods used in the analysis of farming systems.
Authors: Nuthall P. L.
Published: March 2012

Ever since humans moved from simple hunting and gathering, man has contemplated how to produce food and fibre. Today with most western farms having large investments, careful consideration of the 'what, how and when' decisions embodied in a farming system is necessary. Among other objectives, profitability and, when debt levels are high, survivability are important. In the less developed world, analysis is just as important to ensure the greatest output for the minimum resources. This review considers the analytical methods used by farm management professionals in developing practical farming systems. Despite their large investment, most farmers, however, still use the simplest of analytical methods questioning the usefulness of the available tools for other than professionals who provide guiding analyses. Over the last century of both economic and analytical thought, a wide range of theories and techniques have been devised to assist determining farm systems. Any analyst involved in farm management and systems analysis should be fully familiar with the range of available practical tools and theories as this familiarity enables selecting the right tool for each analysis. To help this decision, this review considers the practicality of the tools and methods commonly used. Included are farm surveys, budgeting, cost-benefit analysis, linear (LP) and dynamic (DP) programming, systems simulation and various other operations research techniques. Bench-marking and risk analysis are also important, as are production functions (and estimation methods) and data envelopment analysis (DEA). The use of expert systems as a decision support system is also mentioned.
Epigenetics and plant breeding.
Authors: Rival A. , Jaligot E.
Published: March 2012

The amazing ability of epigenetic mechanisms to respond to a wide range of developmental and environmental signals in eukaryotes has earned them a lot of attention. Indeed, epigenetically regulated gene expression (variations in gene expression obtained without permanent alteration of the DNA sequence) is involved in differentiation, organogenesis and acclimation, and, as such, is hypothesized to participate in both phenotypic diversity and the plasticity of living organisms. While the importance of epigenetic mechanisms in the understanding of such vital processes is now widely recognized, many questions remain to be elucidated. Foremost is the point of transmission of epigenetic marks on (methylated cytosines) and around (modified histone tails) DNA, since research is still needed to explain the inheritance of an epigenetic character and which mechanisms are involved. The present review is aimed at illustrating key concepts when considering the exploitation of epigenetic changes for plant breeding, through both its environmentally responsive character and its potential heritability. In doing so, we have avoided developments relating to complex molecular pathways so as to give a glimpse to the interested but non-expert reader on the current debates and on the experimental challenges still ahead.
Options for control of scolytid beetles that attack pines.
Authors: Glare T. R. , Reay S. D. , Etxebeste I.
Published: March 2012

Scolytid beetles (Coleoptera: Curculionidae: Scolytinae) are a large group of beetles associated with many tree species. Some species consume dead wood and vector an array of fungi which contribute to recycling of organic material, so are often an important component of forest ecology. However, populations can increase to pest levels. In this review, we look at options for control of scolytid pests of
Pinus
spp. Pines, valued for their softwood and pulp, are grown commercially in many countries. Both indigenous and exotic species of bark beetle are pests of pines. There have been numerous approaches to reducing the impact of bark beetle attack on pines. Management strategies have included thinning stands and timing of harvesting and planting, through to efforts to predict outbreaks. Bark beetles use semiochemicals to locate hosts and attract conspecifics and these have been used to trap or repel beetles, or disrupt their behaviour. Chemical pesticides have been used, especially for protection of high-value trees. Pesticides can be effective in some situations, but the commonly used actives such as organophosphates and pyrethroids have non-target and other health and safety concerns. There have been few successful introductions or applications of natural enemies (predators, parasitoids and microbial pathogens) reported for scolytid pests of pines. The cryptic, within-tree, habitats used for much of the bark beetle life cycle provide significant protection against most forms of control. Successful control will require novel approaches and will likely involve multiple agents and strategies.
The role of urban green space and trees in relation to climate change.
Authors: Fryd O. , Pauleit S. , Bühler O.
Published: March 2012

Urban areas are particularly susceptible to climate change. For instance, effects of increasing temperatures on public health and energy demands for cooling of buildings are further intensified by the urban heat island effect, and the current sewer infrastructure is not designed to handle predicted rainstorm events. Urban green spaces can play a role in climate change
mitigation
approaches, but in particular with regard to climate change
adaptation
. This includes moderation of urban temperatures as well as linking green spaces and stormwater management. However, climate change also influences the growth conditions of urban vegetation, and as beneficial effects depend on vital and lush plants, establishment and management practices of urban plantings have to adapt to climate change challenges as well. While environmental, social and economic benefits of urban green space are well established, there is still a significant lack of knowledge for the site adapted planning and design of a green infrastructure in a given location to meet the challenges of climate change.
Downstream Movement of Fall Chinook Salmon Juveniles in the Lower Snake River Reservoirs during Winter and Early Spring
Authors: Tiffan Kenneth F. , Kock Tobias J. , Connor William P. , Mullins Frank , Steinhorst R. Kirk
Published: March 2012

We conducted a 3‐year radiotelemetry study in the lower Snake River to (1) determine whether juvenile fall Chinook salmon Oncorhynchus tshawytscha pass dams during winter, when bypass systems and structures designed to prevent mortality are not operated; (2) determine whether downstream movement rate varies annually, seasonally, and from reservoir to reservoir; and (3) identify some of the factors that contribute to annual, seasonal, and spatial variation in downstream movement rate. Fall Chinook salmon juveniles moved downstream up to 169 km and at a sufficiently fast rate (7.5 km/d) such that large percentages (up to 93%) of the fish passed one or more dams during the winter. Mean downstream movement rate varied annually (9.2–11.3 km/d), increased from winter (7.5 km/d) to spring (16.4 km/d), and increased (from 6.9 to 16.8 km/d) as fish moved downstream from reservoir to reservoir. Fish condition factor at tagging explained some of the annual variation in downstream movement rate, whereas water particle velocity and temperature explained portions of the seasonal variation. An increase in migrational disposition as fish moved downstream helped to explain the spatial variation. The potential cost of winter movement might be reduced survival due to turbine passage at a time when the bypass systems and spillway passage structures are not operated. Efforts to understand and increase passage survival of winter migrants in large impoundments might help to rehabilitate some imperiled anadromous salmonid populations.
Quantitative Analysis of Intestinal Bacterial Populations From Term Infants Fed Formula Supplemented With Fructo‐oligosaccharides
Authors: Xia Qing , Williams Timberly , Hustead Deborah , Price Pamela , Morrison Mark , Yu Zhongtang
Published: March 2012

Objectives:

Previous studies of infant formulas supplemented with oligosaccharides reported mixed results regarding the impact on intestinal microbial populations. The objective of this study was to examine the effect of supplementation of an infant formula with fructo‐oligosaccharides (FOS) on select groups of intestinal bacteria in term infants.

Methods:

Four groups of infants were enrolled and fed human milk, a commercially available milk‐based infant formula, or infant formula supplemented with 2.0 or 3.0 g/L FOS. Dietary intake, stool, and tolerance events were recorded. Fresh stool samples were collected approximately 27 days after feeding the diets (approximately 32 days after birth). Total bacteria, Bacteroides (as commensal bacteria), Bifidobacterium and Lactobacillus, and Clostridium difficile and Escherichia coli were quantified using respective specific real‐time PCR assays.

Results:

The formula feeding groups did not differ in stool consistency and stool frequency or frequency of spit‐up or vomit during the entire study. The formula‐fed infants tended to have more total bacteria in their stool samples than the human milk–fed infants. The formula‐fed infants harbored a greater abundance of C difficile and E coli than the human milk–fed infants, but had a similar abundance of Bacteroides, Bifidobacterium, and Lactobacillus. The FOS supplementation at either dose did not significantly increase the bifidobacterial or lactobacilli populations, or decrease the populations of C difficile, E coli, or Bacteroides.

Conclusions:

The milk‐based formula used in this study supported bifidobacterial and lactobacilli populations comparable with the human milk group; however, this formula did not suppress E coli or C difficile as effectively as human milk.
On the open sea propagation of water waves generated by a moving bed
Authors: Constantin Adrian , Germain Pierre
Published: March 2012

Within the framework of linear theory, applicable far from the shore, we investigate the two-dimensional propagation of waves generated in the ocean by a sudden seabed deformation.
Experimental study of the particle paths in solitary water waves
Authors: Hsu Hung-Chu , Chen Yang-Yih , Hwung Hwung-Hweng
Published: March 2012

We provide experiments that had been conducted to investigate the particle trajectory beneath a solitary water wave. Experimental results show that the surface drift is larger than the bottom drift. Meanwhile, the ratio of the net horizontal displacement to the total height of the trajectory at the free surface and subsurface will decrease with the initial vertical position and increase with the relative wave height.
Note on the velocity and related fields of steady irrotational two-dimensional surface gravity waves
Authors: Clamond Didier
Published: March 2012

The velocity and other fields of steady two-dimensional surface gravity waves in irrotational motion are investigated numerically. Only symmetric waves with one crest per wavelength are considered, i.e. Stokes waves of finite amplitude, but not the highest waves, nor subharmonic and superharmonic bifurcations of Stokes waves. The numerical results are analysed, and several conjectures are made about the velocity and acceleration fields.
Rhodopseudomonas pentothenatexigens sp. nov. and Rhodopseudomonas thermotolerans sp. nov., isolated from paddy soils
Authors: Kumar B. Vinay , Ramprasad E. V. V. , Sasikala Ch. , Ramana Ch. V.
Published: March 2012

Two strains (JA575T and JA576T) of orange- to pink-pigmented, rod-shaped, motile and budding phototrophic bacteria were isolated from paddy soils. Both strains contained bacteriochlorophyll a and carotenoids of spirilloxanthin series. Both strains had C18 : 1ω7c as the major cellular fatty acid, ubiquinone-10 (Q10) as the main quinone, and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine as polar lipids. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that both strains clustered with species of the genus

Rhodopseudomonas

in the class

Alphaproteobacteria

. Strains JA575T and JA576T were genotypically (<35 % DNA–DNA relatedness) and phenotypically distinct from each other. Further, both strains showed less than 48 % DNA–DNA relatedness with the type strains of all recognized species of the genus

Rhodopseudomonas

. The molecular evidence is supported by phenotypic evidence. It is proposed that strains JA575T and JA576T be classified as representing two novel species of the genus

Rhodopseudomonas

with the species names Rhodopseudomonas pentothenatexigens sp. nov. and Rhodopseudomonas thermotolerans sp. nov., respectively. The type strains of the proposed novel species are JA575T ( = NBRC 108862T = KCTC15143T) and JA576T ( = NBRC 108863T = KCTC 15144T), respectively.
Transfer of

Wautersia numazuensis

to the genus

Cupriavidus

as Cupriavidus numazuensis comb. nov.
Authors: Martínez-Aguilar Lourdes , Caballero-Mellado Jesús , Estrada-de los Santos Paulina
Published: March 2012

Phylogenetic analysis of the 16S rRNA gene sequences of strains TE26T and K6 belonging to

Wautersia numazuensis

Kageyama et al. 2005 showed the strains to be deeply intermingled among the species of the genus

Cupriavidus

. The comparison showed that strain TE26T was closely related to the type strains of

Cupriavidus pinatubonensis

(99.1 % 16S rRNA gene sequence similarity),

C. basilensis

(98.7 %),

C. necator

(98.7 %) and

C. gilardii

(98.0 %). However, DNA–DNA hybridization experiments (less than 20 % relatedness) demonstrated that strain TE26T is different from these

Cupriavidus

species. A comparative phenotypic and chemotaxonomic analysis (based on fatty acid profiles) in combination with the 16S rRNA gene sequence phylogenetic analysis and the DNA–DNA hybridization results supported the incorporation of

Wautersia numazuensis

into the genus

Cupriavidus

as Cupriavidus numazuensis comb. nov.; the type strain is TE26T ( = LMG 26411T  = DSM 15562T  = CIP 108892T).
Reclassification of

Koreibacter algae

as a later heterotypic synonym of

Paraoerskovia marina

and emended descriptions of the genus

Paraoerskovia

Khan et al. 2009 and of

Paraoerskovia marina

Khan et al. 2009
Authors: Schumann P. , Pukall R. , Spröer C. , Stackebrandt E.
Published: March 2012

16S rRNA gene sequences deposited for the type strains of

Paraoerskovia marina

(CTT-37T; GenBank accession no. AB445007) and

Koreibacter algae

(DSW-2T; FM995611) show a similarity of 100 %. Consequently, the type strains were subjected to a polyphasic recharacterization under direct comparison in order to clarify their taxonomic position. PvuII RiboPrint patterns and quantitative ratios of cellular fatty acids revealed strain-specific differences between

P. marina

DSM 21750T ( = CTT-37T) and

K. algae

DSM 22126T ( = DSW-2T). The percentage of DNA–DNA binding of 94 % indicated that the two type strains belong to the same genomospecies. Agreement in the peptidoglycan structure and polar lipid pattern, highly similar fatty acid profiles and MALDI-TOF mass spectra, the ability to produce acid from the same carbon sources, corresponding enzymic activities and DNA G+C contents of 70.8±0.3 mol%, in addition to the consistent characteristics reported in the original descriptions, support the view that the two strains should be affiliated to the same species. According to Rules 38 and 42 of the Bacteriological Code,

Koreibacter algae

should be reclassified as later heterotypic synonym of

Paraoerskovia marina

, and the descriptions of the genus

Paraoerskovia

Khan et al. 2009 and of

Paraoerskovia marina

Khan et al. 2009 are emended accordingly.
Smooth and near time‐optimal trajectory planning of industrial robots for online applications
Authors: Xiao Yongqiang , Du Zhijiang , Dong Wei
Published: March 2012

Purpose

The purpose of this paper is to propose a new smooth online near time‐optimal trajectory planning approach to reduce the consuming time compared to the conventional dynamics trajectory planning methods.

Design/methodology/approach

In the proposed method, the robot path is expressed by a scalar path coordinate. The joints torque boundary and speed boundary are transformed into the plane, which can generate the limitation curves of pseudo‐velocity. The maximum pseudo‐velocity curve that meets the limits of torque and speed is built up through the feature points and control points in the plane by using cubic polynomial fitting method. Control points used for cubic polynomial construction are optimized by the Golden‐Section method.

Findings

The proposed method can avoid Range's phenomenon and also guarantee the continuity of torque.

Practical implications

The algorithm designed in this paper is used for the controller of a new industrial robot which will be equipped for the welding automatic lines of Chery Automobile Co. Ltd.

Originality/value

Compared to the five‐order polynomial trajectory optimization method proposed by Macfarlane and Croft, the approach described in this paper can effectively take advantage of joints maximum speed, and the calculation time of this method is shorter than conventional dynamics methods.
Knowledge creation and flexibility of distribution of information
Authors: Mihi Ramírez Antonio , Jesús García Morales Víctor , Arias Aranda Daniel
Published: March 2012

Purpose

The purpose of this paper is to increase knowledge about the four modes of knowledge conversion (SECI model: Socialization, Externalization, Combination, Internalization) and their impact on flexibility of distribution of information and performance.

Design/methodology/approach

Based on a survey of 284 Spanish firms, the paper performs an empirical analysis using structural equation modelling.

Findings

The results of the research confirm that the four modes of knowledge conversion have positive direct and indirect influences on the flexibility of distribution of information in the organization and therefore improve the company's performance.

Practical implications

The structural equation model provides useful information for managers and researchers concerning how knowledge creation enhances flexibility and performance of the organization. Through better processes and tools for updating the organization's concepts or methods, flexibility programs, cross functional and self‐directed teams, autonomy, participation, cooperation and coordination in the firm improve the flow of information and performance and reduce uncertainty in changing environments.

Originality/value

The paper illustrates the effects of the four modes of knowledge creation on flexibility of distribution of information and demonstrates that these four modes of knowledge creation affect flexibility of distribution of information positively, thereby improving organizational performance.