bluuebunny/crossref_metadata_2025 huggingface dataset:
A Threshold Phenomenon for Random Independent Sets in the Discrete Hypercube
Authors: GALVIN DAVID
Published: July 2010

Let I be an independent set drawn from the discrete d-dimensional hypercube Qd = {0, 1}d according to the hard-core distribution with parameter λ > 0 (that is, the distribution in which each independent set I is chosen with probability proportional to λ|I|). We show a sharp transition around λ = 1 in the appearance of I: for λ > 1, min{|I ∩ Ɛ|, |I ∩ |} = 0 asymptotically almost surely, where Ɛ and are the bipartition classes of Qd, whereas for λ < 1, min{|I ∩ Ɛ|, |I ∩ |} is asymptotically almost surely exponential in d. The transition occurs in an interval whose length is of order 1/d.

A key step in the proof is an estimation of Zλ(Qd), the sum over independent sets in Qd with each set I given weight λ|I| (a.k.a. the hard-core partition function). We obtain the asymptotics of Zλ(Qd) for $\gl>\sqrt{2}-1$, and nearly matching upper and lower bounds for $\gl \leq \sqrt{2}-1$, extending work of Korshunov and Sapozhenko. These bounds allow us to read off some very specific information about the structure of an independent set drawn according to the hard-core distribution.

We also derive a long-range influence result. For all fixed λ > 0, if I is chosen from the independent sets of Qd according to the hard-core distribution with parameter λ, conditioned on a particular v ∈ Ɛ being in I, then the probability that another vertex w is in I is o(1) for w ∈ but Ω(1) for w ∈ Ɛ.
Study of the Changes in Insoluble Polysaccharides during Pollen Development in Rice (Oryza sativa L.) by Microscopic Multispectral Imaging
Authors: Liu Shunan , Pan Lei , Wu Qiongshui , Hu Yaojun , Chen Xiaojun , Ding Yi
Published: July 2010

Multispectral analysis combined with the Periodic Acid-Schiff method was used to investigate cytological features of insoluble polysaccharides and changes in total insoluble polysaccharide content (TPC) during pollen development in rice, including four cytoplasmic male sterility lines (MSLs) and their corresponding fertility-maintaining lines (FMLs). The multispectral curves of the relative transmittance value (RTV) and the images of developing pollen cells were obtained across a range of successive wavelengths (400–720 nm). A minimum RTV was found near 550 nm indicating an absorption peak of the TPC. Thus, the TPC was measured using the RTV of 550 nm. In the four FMLs, the minimum TPC of developing pollen cells occurred at the late microspore stage, while the maximum TPC occurred at the mature pollen grain stage. The TPC levels of pollen cells were significantly higher in the four FMLs than in their corresponding MSLs during and after pollen abortion. Notably, a steep decrease of multispectral curves at 420 nm appeared before the occurrence of abortion, implying a marker associated with pollen abortion in rice. Our results will be helpful for exploring the changes in TPC during pollen ontogenesis in rice and provide a novel method for the study of bio-macromolecules.
Imaging, Core-Loss, and Low-Loss Electron-Energy-Loss Spectroscopy Mapping in Aberration-Corrected STEM
Authors: Lazar Sorin , Shao Yang , Gunawan Lina , Nechache Riad , Pignolet Alain , Botton Gianluigi A.
Published: July 2010

High-angle annular dark-field and annular bright-field imaging experiments were carried out on an aberration-corrected transmission electron microscope. These techniques have been demonstrated on thin films of complex oxides Ba3.25La0.75Ti3O12 and on LaB6. The results show good agreement between theory and experiments, and for the case of LaB6 they demonstrate the detection of contrast from the B atoms in the annular bright-field images. Elemental mapping with electron-energy-loss spectroscopy has been used to deduce the distribution of Cr and Fe in a thin film of the complex oxide Bi2(Fe1/2Cr3/2)O6 at the unit cell level and the changes in the near-edge structure within the inequivalent regions in the crystalline unit cell. Energy-filtered images in the low-loss region of the energy-loss spectrum show contrast and resolution consistent with the modulation of the signals from elastic scattering. High-resolution contrast, mediated by phonon scattering, is observed for interband transitions. The limitations in terms of detection and signal are discussed.
Institutional Patterns in the New Democracies of Asia: Forms, Origins and Consequences
Authors: CROISSANT AUREL , SCHÄCHTER TERESA
Published: July 2010

This article analyzes the institutional patterns of eight young democracies in Asia. The analysis originates from Lijphart's majoritarian-consensus framework. It illustrates that neither Lijphart's two-dimensional democracy pattern, nor an alternative pattern exists in Asia. Instead, the review of possible causes for the lack of conformity between Lijphart's patterns of democracy and the reality of the situation in Asia support the criticism in existing research literature regarding some of Lijphart's main assumptions and major conclusions. Furthermore, Asian realities provide only partial support for Lijphart's advice that the consensus option is the more attractive option for countries that designed their first democratic constitutions.
Development Assistance, Strategic Interests, and the China Factor in Japan's Role in ASEAN Integration
Authors: YOSHIMATSU HIDETAKA , TRINIDAD DENNIS D.
Published: July 2010

In this article, we have examined how Japan has supported ASEAN's economic integration through ODA and other diplomatic measures, and showed how Japan's engagements in ASEAN economic integration evolved over time. In addressing these issues, we took into account the growing influence of China's ascent in Southeast Asia, and assumed that Japan's China policy of mixed ‘accommodation and balance’ became explicit in Japan's ASEAN policy. The pronouncement of support for ASEAN integration, disbursement of aid to the region, forging of bilateral and regional FTAs/EPAs with ASEAN, and its recent initiatives and proactive involvement in the Mekong regional development are indicative of Japan's reactive posture on China's growing influence in the region. Japanese diplomatic initiatives in ASEAN are intended, in part, to accommodate and balance China's increasing prominence in Southeast Asia. This explains the simultaneous existence of competitive and cooperative initiatives of the two countries with ASEAN.
Phylogeographic separation of marine and soil myxobacteria at high levels of classification
Authors: Jiang De-Ming , Kato Chiaki , Zhou Xiu-Wen , Wu Zhi-Hong , Sato Takako , Li Yue-Zhong
Published: July 2010

Microorganisms are globally dispersed and are able to proliferate in any habitat that supports their lifestyles, which, however, has not yet been explored in any specific microbial taxon. The social myxobacteria are considered typical soil bacteria because they have been identified in various terrestrial samples, a few in coastal areas, but none in other oceanic environments. To explore the prevalence of marine myxobacteria and to investigate their phylogenetic relationships with their terrestrial counterparts, we established myxobacteria-enriched libraries of 16S rRNA gene sequences from four deep-sea sediments collected at depths from 853 to 4675 m and a hydrothermal vent at a depth of 204 m. In all, 68 different myxobacteria-related sequences were identified from randomly sequenced clones of the libraries of different samples. These myxobacterial sequences were diverse but phylogenetically similar at different locations and depths. However, they were separated from terrestrial myxobacteria at high levels of classification. This discovery indicates that the marine myxobacteria are phylogeographically separated from their terrestrial relatives, likely because of geographic separation and environment selection.
Communication Development and Differences in Children Adopted From China and Eastern Europe
Authors: Hwa-Froelich Deborah A. , Matsuo Hisako
Published: July 2010

Purpose

The communication development of children adopted from China and Eastern Europe was compared by region of origin at 6 and 12 months after adoption.

Method

Twenty children, recruited before or immediately following their adoption, participated in the study. Measures were collected between 2 and 6 months after adoption (Time 1) and between 12 and 14 months after adoption (Time 2). The children’s ages ranged between 11–22 months and 22–34 months, respectively. Parent-reported vocabulary comprehension and expression and behavioral communication assessments were administered.

Results

No significant differences between region of origin were found at Time 1. At Time 2, significant group differences in expressive language performance were found, with children adopted from China and Eastern Europe demonstrating different patterns of English language development.

Conclusion

Early prelinguistic measures may provide prognostic indicators for later English language development. Children adopted from different countries where they are initially exposed to different birth languages may acquire English differently.
High temperature stress-induced “double loop-like” phase transitions in Bi-based perovskites
Authors: Webber K. G. , Zhang Y. , Jo Wook , Daniels J. E. , Rödel J.
Published: July 2010

Polycrystalline 0.94(Bi1/2Na1/2)TiO3–0.06BaTiO3 samples were tested under uniaxial mechanical compression at various temperatures in the vicinity of the polar tetragonal to nonpolar tetragonal phase boundary. They are shown to display double loop-like stress-strain behavior, marked by a closed ferroelastic hysteresis loop. Thus, it forms a mechanical analog to the polarization-electric field hysteresis behavior of barium titanate above the Curie temperature. As temperature is increased there is an apparent loss of macroscopically observable ferroelasticity, despite the persistence of tetragonality. Macroscopic experimental results are discussed in conjunction with temperature-dependent and stress-dependent high-energy x-ray diffraction data. This reveals a phase transition below the Curie temperature, marked by a discontinuous change in lattice parameters and octahedral tilting during compressive mechanical loading.
A deformation quantization theory for noncommutative quantum mechanics
Authors: Dias Nuno Costa , de Gosson Maurice , Luef Franz , Prata João Nuno
Published: July 2010

We show that the deformation quantization of noncommutative quantum mechanics previously considered by Dias and Prata [“Weyl–Wigner formulation of noncommutative quantum mechanics,” J. Math. Phys. 49, 072101 (2008)] and Bastos, Dias, and Prata [“Wigner measures in non-commutative quantum mechanics,” e-print arXiv:math-ph/0907.4438v1; Commun. Math. Phys. (to appear)] can be expressed as a Weyl calculus on a double phase space. We study the properties of the star-product thus defined and prove a spectral theorem for the star-genvalue equation using an extension of the methods recently initiated by de Gosson and Luef [“A new approach to the ⋆-genvalue equation,” Lett. Math. Phys. 85, 173–183 (2008)].
Evaluating luminescence based voltage images of silicon solar cells
Authors: Glatthaar M. , Haunschild J. , Zeidler R. , Demant M. , Greulich J. , Michl B. , Warta W. , Rein S. , Preu R.
Published: July 2010

In this paper we give a mathematical derivation of how luminescence images of silicon solar cells can be calibrated to local junction voltage. We compare two different models to extract spatially resolved physical cell parameters from voltage images. The first model is the terminal connected diode model, where each pixel is regarded as a diode with a certain dark saturation current, which is connected via a series resistance with the terminal. This model is frequently used to evaluate measurement data of several measurement techniques with respect to local series resistance. The second model is the interconnected diode model, where the diode on one pixel is connected with the neighbor diodes via a sheet resistance. For each model parameter at least one image is required for a coupled determination of the parameters. We elaborate how also the voltage calibration can be added as an unknown parameter into the models, and how the resulting system of equations can be solved analytically. Finally the application of the models and the different ways of voltage calibration are compared experimentally.
Detection of mechanical resonance of a single-electron transistor by direct current
Authors: Pashkin Yu. A. , Li T. F. , Pekola J. P. , Astafiev O. , Knyazev D. A. , Hoehne F. , Im H. , Nakamura Y. , Tsai J. S.
Published: July 2010

We have suspended an Al based single-electron transistor (SET) whose island can resonate freely between the source and drain leads forming the clamps. In addition to the regular side gate, a bottom gate with a larger capacitance to the SET island is placed underneath to increase the SET coupling to mechanical motion. The device can be considered as a doubly clamped Al beam that can transduce mechanical vibrations into variations in the SET current. Our simulations based on the orthodox model, with the SET parameters estimated from the experiment, reproduce the observed transport characteristics in detail.
Mechanical properties of rippled structure in suspended stacks of graphene
Authors: Lee Hyunsoo , Yong HyeonDeuk , Kim K. B. , Seo Yongho , Yun Hoyeol , Lee SangWook
Published: July 2010

We studied the mechanical properties of a suspended graphene layers which have ripples with stripe pattern, by using an atomic force spectroscopy. The local spring constant of the rippled graphene layer has larger value at concave region and smaller at convex region. The attractive force and pull-off force between a tip and the sample also have larger values at the concave region. A local spring constant mapping on the suspended graphene with ripple was obtained and nonlinear behavior of the force-distance curve was analyzed regarding local deformation of the sample.
Effects of single-layer Shockley stacking faults on the transport properties of high-purity semi-insulating 4H–SiC
Authors: Fabbri F. , Cavallini A.
Published: July 2010

The electrical properties of high-purity 4H–SiC epitaxial layers are investigated. The current density versus applied voltage curves shows that some specimens have space charge limited transport behavior. Lampert–Mark model for trap-controlled electron transport in semi-insulating materials demonstrated the presence of an intragap state at 0.26 eV below the conduction band. Photodeep level transient spectroscopy has confirmed the presence of a deep level at about 0.3 eV below the conduction band only in samples with non-Ohmic behavior. Cathodoluminescence imaging has revealed the presence of high luminescent areas related to stacking faults (SFs) under the devices showing non-Ohmic behavior. The presence of single-layer SFs was detected by cathodoluminescence spectroscopy due to the typical emission at 2.95 eV. Thus, we demonstrated that the SFs modified the charge transport from Ohmic conduction to space charge limited conduction of the affected samples.
Infrared study of the absorption edge of β-InN films grown on GaN/MgO structures
Authors: Pérez-Caro M. , Rodríguez A. G. , Vidal M. A. , Navarro-Contreras H.
Published: July 2010

Infrared optical studies were carried out in a group of cubic InN samples grown by gas source molecular beam epitaxy on MgO (001) substrates. Room temperature (RT) reflectance and low-temperature (LT) transmittance measurements were performed by using fast Fourier transform infrared spectrometry. Reflectance fittings allowed to establish that β-InN films have large free-carrier concentrations present (>1019 cm−3), a result that is corroborated by Hall effect measurements. Each sample explored exhibited a different optical absorption edge. The Varshni parameters that describe adequately the optical absorption edge responses with temperature are obtained for the set of samples studied. The observed temperatures changes, from LT to RT, are the lowest reported for III-V semiconductor binary compounds. The temperature coefficient of the conduction band depends on the strength of the electron–phonon interaction (e-ph-i), as well as on the thermal expansion. It has been predicted that cubic InN has one of the smallest e-ph-i of all III-V compounds, which is corroborated by these results. The variation in values of absorption edges is clearly consistent with the Burstein–Moss and band renormalization effects, produced by high free electron concentrations. It is shown that the conduction band in β-InN, analogous to wurtzite InN, follows a nonparabolic behavior.
Adsorption-controlled growth of BiMnO3 films by molecular-beam epitaxy
Authors: Lee J. H. , Ke X. , Misra R. , Ihlefeld J. F. , Xu X. S. , Mei Z. G. , Heeg T. , Roeckerath M. , Schubert J. , Liu Z. K. , Musfeldt J. L. , Schiffer P. , Schlom D. G.
Published: July 2010

We have developed the means to grow BiMnO3 thin films with unparalleled structural perfection by reactive molecular-beam epitaxy and determined its band gap. Film growth occurs in an adsorption-controlled growth regime. Within this growth window bounded by oxygen pressure and substrate temperature at a fixed bismuth overpressure, single-phase films of the metastable perovskite BiMnO3 may be grown by epitaxial stabilization. X-ray diffraction reveals phase-pure and epitaxial films with ω rocking curve full width at half maximum values as narrow as 11 arc sec (0.003°). Optical absorption measurements reveal that BiMnO3 has a direct band gap of 1.1±0.1 eV.
Spatially resolved ultrafast transport current in GaAs photoswitches
Authors: Prechtel L. , Manus S. , Schuh D. , Wegscheider W. , Holleitner A. W.
Published: July 2010

We apply a pump- and probe-scheme to coplanar stripline circuits to investigate the photocurrent response of GaAs photoswitches in time and space. We find a displacement current pulse, as reported earlier. We interpret a time-delayed second pulse as a transport current. In a time-of-flight analysis we determine the velocity of the photogenerated charge carriers in the transport current. It exceeds the Fermi and the single-particle quantum velocities. This suggests that the excitation of an electron-hole plasma and not single charge-carriers dominates the ultrafast transport current in GaAs photoswitches.
Phonon wave-packet interference and phonon tunneling based energy transport across nanostructured thin films
Authors: Tian Z. T. , White B. E. , Sun Y.
Published: July 2010

The molecular dynamics based phonon wave-packet technique is used to study phonon transport across mass-mismatched fcc thin films. Transport behavior of normally incident longitudinal acoustic phonon wave packets with wave vectors ranging in magnitude from 2% to 50% of the ⟨100⟩ first Brillouin zone boundary is examined as a function of thin film thickness when the phonon mean free path exceeds film thickness. The results indicate that for thin film to bulk solid mass ratios up to a factor of 6, the transmission of energy through the thin film can be well described by treating the thin film as a bulk solid.
Direct-write, focused ion beam-deposited, 7 K superconducting C–Ga–O nanowire
Authors: Dhakal Pashupati , McMahon G. , Shepard S. , Kirkpatrick T. , Oh J. I. , Naughton M. J.
Published: July 2010

We have fabricated C–Ga–O nanowires by gallium focused ion beam-induced deposition from the carbon-based precursor phenanthrene. The electrical conductivity of the nanowires is weakly temperature dependent below 300 K and indicates a transition to a superconducting state below Tc=7 K. We have measured the temperature dependence of the upper critical field Hc2(T) and estimate a zero temperature critical field of 8.8 T. The Tc of this material is approximately 40% higher than that of any other direct write nanowire, such as those based on C–W–Ga, expanding the possibility of fabricating direct-write nanostructures that superconduct above liquid helium temperatures.
Crystallographic orientation engineering in silicon-on-insulator substrates
Authors: Signamarcheix T. , Biasse B. , Papon A.-M. , Nolot E. , Mazen F. , Leveneur J. , Faynot O. , Clavelier L. , Ghyselen B.
Published: July 2010

A bilayer silicon-on-insulator film was engineered to locally convert the crystallographic orientation from (100) to (110). The initial bilayer film is composed of a first 50 nm thick (110) oriented Si surface layer, above a second 20 nm thick (100) oriented Si underlayer. The bilayer film was elaborated using hydrophobic bonding to ensure an atomic contact between the two layers without any intermediate oxide. A local and deep-amorphization was developed by ion implantation to amorphize the (100) oriented Si underlayer, conserving also a partially crystalline (110) oriented surface layer. After such a deep amorphization, a solid phase epitaxy regrowth was performed at 900 °C. Transmission electron microscopy observations confirm that the partially crystalline surface layer acts as a seed for the epitaxial regrowth of the amorphized areas through the hydrophobic bonding interface. Thus, the orientation is locally converted from (100) to (110) in the underlayer, which could lead to the elaboration of hybrid films over a continuous insulating oxide that are mandatory for high performance electronic devices.
Directional dependence of the second harmonic response in two-dimensional nonlinear photonic crystals
Authors: Molina P. , Ramírez M. O. , García B. J. , Bausá L. E.
Published: July 2010

A two-dimensional periodic arrangement of alternating ferroelectric domains in LiNbO3, with asymmetric domain duty cycle has been used to demonstrate that counterpropagating beams along the polar axis can generate disparate second harmonic patterns, which are nonsymmetrical with respect to the source and the point of observation. These findings provide alternative routes to generate dissimilar light-matter interaction processes in two-dimensional structures assembled onto polar surfaces, including metals for plasmonics or biological compounds.
Different nonvolatile memory effects in epitaxial Pt/PbZr0.3Ti0.7O3/LSCO heterostructures
Authors: Choi Jinsik , Kim Jin-Soo , Hwang Inrok , Hong Sahwan , Byun Ik-Su , Lee Seung-Woong , Kang Sung-Oong , Park Bae Ho
Published: July 2010

We found different nonvolatile memory effects between ferroelectric and resistive switching in Pt/PbZr0.3Ti0.7O3(PZT)/La0.5Sr0.5CoO3 (LSCO) heterostructures, depending on thickness of epitaxial PZT films. As the film thickness decreased below 34 nm, leakage and/or tunneling currents increased and hindered ferroelectric switching of films; alternatively, bipolar resistive switching was observed. Analysis using fitting plot on resistive switching behaviors suggested that variable Schottky barrier at the interface between Pt electrode and the film may be responsible for the different nonvolatile memory switching.
The response of barley to salinity stress differs between hydroponic and soil systems
Authors: Tavakkoli Ehsan , Rengasamy Pichu , McDonald Glenn K.
Published: July 2010

Many studies on salinity stress assume that responses in hydroponics mimic those in soil. However, interactions between the soil solution and the soil matrix can affect responses to salinity stress. This study compared responses to salinity in hydroponics and soil, using two varieties of barley (Hordeum vulgare L.). The responses to salinity caused by high concentrations of Na+ and Cl– were compared to assess any consistent differences between hydroponics and soil associated with a cation and an anion that contribute to salinity stress. Concentrated nutrient solutions were also used to assess the effects of osmotic stress. The effects of salinity differed between the hydroponic and soil systems. Differences between barley cultivars in growth, tissue moisture content and ionic composition were not apparent in hydroponics, whereas significant differences occurred in soil. Growth reductions were greater under hydroponics than in soil at similar electrical conductivity values, and the uptake of Na+ and Cl– was also greater. The relative importance of ion exclusion and osmotic stress varied. In soil, ion exclusion tended to be more important at low to moderate levels of stress (EC at field capacity up to 10 dS m–1) but osmotic stress became more important at higher stress levels. High external concentrations of Cl– had similar adverse effects as high concentrations of Na+, suggesting that Cl– toxicity may reduce growth. Fundamental differences in salinity responses appeared between soil and solution culture, and the importance of the different mechanisms of damage varies according to the severity and duration of the salt stress.
Dynamic quantitative trait loci for salt stress components on chromosome 1 of rice
Authors: Ul Haq Tanveer , Gorham John , Akhtar Javaid , Akhtar Nasim , Steele Katherine A.
Published: July 2010

Rice varieties Co39 and Moroberekan differ for leaf Na+ concentrations when grown at moderate salinity (100–150 mol m–3 NaCl; 10 : 1 or 20 : 1 Na+ to Ca2+ ratio). Recombinant inbred lines (RILs) from a cross between them were used to map quantitative trait loci (QTL) under salt stress over several weeks. Two experiments (conducted with 170 and 96 RILs, and a linkage map of 126 RFLP markers) identified a major effect on QTL for leaf Na+ concentration and K+ : Na+ ratio on chromosome 1 in a region corresponding to 11.07–14.6 Mbp. No leaf Cl– QTL were detected. In a third experiment, leaves and sheaths were harvested after 7 and 21 days at 100 mol m–3 NaCl. The linkage map of chromosome 1 was improved by the addition of 28 microsatellite markers, which resolved distinct QTL for Na+ and K+ concentrations, and K+ : Na+ ratio. After 7 days’ stress, the most significant QTL were in the region of 11.56–12.66 Mbp. The highest Na+ concentrations were recorded in the sheaths. Na+ concentration QTL were detected for leaves, but not for sheaths. After 21 days’ stress, the region containing the most significant QTL extended to 11.07 Mbp in leaves and in sheaths. A QTL for the ratio of leaf Na+ to sheath Na+ concentrations was found at 11.39–12.39 Mbp. These findings suggest that multiple genes in this region are involved in the response to salinity, and their impact is dynamic according to stress duration, and leaf age and type.
The effect of saline hypoxia on growth and ion uptake in Suaeda maritima
Authors: Wetson Anne M. , Flowers Timothy J.
Published: July 2010

The widely occurring annual halophyte Suaeda maritima experiences fluctuating salt and oxygen concentration during tidal cycles in salt marshes and shows tolerance of extreme hypoxia. The effect of saline waterlogging on growth and ion accumulation was investigated in tanks in a glasshouse where tidal flow was simulated, and in an aerated and hypoxic saline nutrient solution in a controlled environment cabinet. Laboratory data were compared with data from a survey of growth in two salt marshes. Plants in the nutrient solution grew equally well in the alternative nitrogen sources, NO3– and NH4+. Hypoxia, produced in the nutrient solution by nitrogen bubbling in the absence of turbulence and using stagnant agar, reduced root growth; hypoxia in waterlogged pot media in the glasshouse also reduced shoot growth and net K+ uptake but increased net uptake of Na+ and Cl–. 22Na+ influx into shoots was only significantly reduced by hypoxia when combined with a sudden increase in salt concentration to 200 mM NaCl. S. maritima appears to be well adapted to tolerate severely hypoxic growth conditions.
Hormonal regulation of source - sink relations to maintain crop productivity under salinity: a case study of root-to-shoot signalling in tomato
Authors: Pérez-Alfocea Francisco , Albacete Alfonso , Ghanem Michel E. , Dodd Ian C.
Published: July 2010

Salinity decreases crop yield first by reducing growth of assimilate-consuming sink organs and, second, by decreasing assimilate production in photosynthetically active source tissues. Although much work has focussed on controlling the accumulation of toxic ions (mainly Na+ and Cl–), the search for primary growth limiting factor(s) continues. The root, by sensing environmental constraints of the soil, may influence root-to-shoot signalling to control shoot growth and physiology, and ultimately agricultural productivity. Hormonal signals, such as cytokinins, ABA, the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and the auxin indole-3-acetic acid may coordinate assimilate production and usage in competing sinks (biomass partitioning). Hormonal regulation of source–sink relations during the osmotic phase of salinity (independent of specific ions) affects whole-plant energy availability to prolong the maintenance of growth, root function and ion homeostasis, and could be critical to delay the accumulation of Na+ or any other ion to toxic levels. This viewpoint emphasises that simultaneously maintaining growth and delaying early leaf senescence is necessary to increase crop yield in salt-affected soils.
Scaling up: the essence of effective agricultural research
Authors: Passioura J. B.
Published: July 2010

Successful scaling up from laboratory research to application in the field depends on practitioners being aware of the constraints and other interactions that arise as scaling up proceeds. Although exploration of promising ideas are often of intrinsic scientific interest, such ideas fail the test of utility if they do not get adopted by agronomists or plant breeders, and if practices and cultivars based on such ideas do not get adopted by farmers. This notion of scaling up is explored here using salinity tolerance of crops as a case study, with examples drawn from gene expression, tissue culture, controlled environment studies of plants grown in hydroponics and in pots, and the behaviour of plants at the field scale. The most effective research in this arena has resulted from a culture of collegiate dialogue between scientists working at different scales.
Multivariate polynomial approximation for equidistant data
Authors: Mond B.
Published: July 2010

The theory of polynomial approximation for evenly spaced points is extended to multivariate polynomial approximation. It is also shown how available tables prepared for univariate approximation can be used in the multivariate case.
A map-folding problem
Authors: Lunnon W. F.
Published: July 2010

An algorithm is described to compute the number of ways of folding a one-dimensional map, and a table of values given.
A family of variable-metric methods derived by variational means
Authors: Goldfarb Donald
Published: July 2010

A new rank-two variable-metric method is derived using Greenstadt’s variational approach [Math. Comp., this issue]. Like the Davidon-Fletcher-Powell (DFP) variable-metric method, the new method preserves the positive-definiteness of the approximating matrix. Together with Greenstadt’s method, the new method gives rise to a one-parameter family of variable-metric methods that includes the DFP and rank-one methods as special cases. It is equivalent to Broyden’s one-parameter family [Math. Comp., v. 21, 1967, pp. 368–381]. Choices for the inverse of the weighting matrix in the variational approach are given that lead to the derivation of the DFP and rank-one methods directly.
Maximum norm stability of difference approximations to the mixed initial boundary-value problem for the heat equation
Authors: Varah J. M.
Published: July 2010

We consider the heat equation

u
t

=

u

x
x

{u_t} = {u_{xx}}

in the quarter-plane

x
≧
0

x \geqq 0

,

t
≧
0

t \geqq 0

with initial condition

u
(
x
,
0
)
=
f
(
x
)

u(x,0) = f(x)

and boundary condition

α
u
(
0
,
t
)
+

u
x

(
0
,
t
)
=
0

\alpha u(0,t) + {u_x}(0,t) = 0

. We are concerned with the stability of difference approximations

υ
ν

n
+
1

=
Q

υ
ν

n

{\upsilon _\nu }^{n + 1} = Q{\upsilon _\nu }^n

to this problem. Using the resolvent operator

(
Q
−
z
I

)

−
1

{(Q - zI)^{ - 1}}

, we give sufficient conditions for consistent, onestep explicit schemes to be stable in the maximum norm.
Computing invariant subspaces of a general matrix when the eigensystem is poorly conditioned
Authors: Varah J. M.
Published: July 2010

The problem of calculating the eigensystem of a general complex matrix is well known. In many cases, however, the eigensystem is poorly determined numerically in the sense that small changes in the matrix can cause large changes in the eigensystem. For these matrices, a decomposition into higher-dimensional invariant subspaces is desirable. In this paper we define a class of matrices where this is true, and propose a technique for calculating bases for these invariant subspaces. We show that for this class the technique provides basis vectors which are accurate and span the subspaces well.
Mammalian cell growth versus biofilm formation on biomaterial surfaces in an in vitro post-operative contamination model
Authors: Subbiahdoss Guruprakash , Kuijer Roel , Busscher Henk J. , van der Mei Henny C.
Published: July 2010

Biomaterial-associated infections are the major cause of implant failure and can develop many years after implantation. Success or failure of an implant depends on the balance between host tissue integration and bacterial colonization. Here, we describe a newin vitromodel for the post-operative bacterial contamination of implant surfaces and investigate the effects of contamination on the balance between mammalian cell growth and bacterial biofilm formation. U2OS osteosarcoma cells were seeded on poly(methyl methacrylate) in different densities and allowed to grow for 24 h in a parallel-plate flow chamber at a low shear rate (0.14 s−1), followed by contamination withStaphylococcus epidermidisATCC 35983 at a shear rate of 11 s−1. The U2OS cells and staphylococci were allowed to grow simultaneously for another 24 h under low-shear conditions (0.14 s−1). Mammalian cell growth was severely impaired when the bacteria were introduced to surfaces with a low initial cell density (2.5×104cells cm−2), but in the presence of higher initial cell densities (8.2×104cells cm−2and 17×104cells cm−2), contaminating staphylococci did not affect cell growth. This study is believed to be the first to show that a critical coverage by mammalian cells is needed to effectively protect a biomaterial implant against contaminating bacteria.
Resources and transgenesis techniques for functional genomics in Xenopus
Authors: Ogino Hajime , Ochi Haruki
Published: July 2010

Recent developments in genomic resources and high‐throughput transgenesis techniques have allowed Xenopus to ‘metamorphose’ from a classic model for embryology to a leading‐edge experimental system for functional genomics. This process has incorporated the fast‐breeding diploid frog, Xenopus tropicalis, as a new model‐system for vertebrate genomics and genetics. Sequencing of the X. tropicalis genome is nearly complete, and its comparison with mammalian sequences offers a reliable guide for the genome‐wide prediction of cis‐regulatory elements. Unique cDNA sets have been generated for both X. tropicalis and X. laevis, which have facilitated non‐redundant, systematic gene expression screening and comprehensive gene expression analysis. A variety of transgenesis techniques are available for both X. laevis and X. tropicalis, and the appropriate procedure may be chosen depending on the purpose for which it is required. Effective use of these resources and techniques will help to reveal the overall picture of the complex wiring of gene regulatory networks that control vertebrate development.
Quantitative diffusion tensor tractography of the motor and sensory tract in children with cerebral palsy
Authors: YOSHIDA SHOKO , HAYAKAWA KATSUMI , YAMAMOTO AKIRA , OKANO SOUZO , KANDA TOYOKO , YAMORI YURIKO , YOSHIDA NAOKO , HIROTA HARUYO
Published: July 2010

Aim  The aim of this study was to compare the findings of quantitative diffusion tensor tractography of the motor and sensory tracts in children with cerebral palsy (CP) and typically developed comparison individuals, and also to evaluate the correlation with gross motor function.

Method  Thirty‐four children with CP (mean age 2y 2.mo, SD 2y 0mo; 19 with spastic diplegia, eight with hemiplegia, six with spastic quadriplegia, and one with spastic triplegia) and 21 healthy comparison children (mean 2y 1.68mo, SD 2y 8.64mo) were evaluated. The distribution of Gross Motor Function Classification System (GMFCS) levels in the CP group was as follows: level I, 7; level II, 14; level III, 5; level IV, 3; and level V, 5. The following three diffusion tensor imaging (DTI) parameters including tractography were evaluated for each tract (corticospinal tract [CST] and posterior thalamic radiation [PTR]): number of fibres, tract‐based fractional anisotropy, and region of interest (ROI)‐based fractional anisotropy. We compared each value between the two groups, and correlated each value with the GMFCS level.

Results  The number of fibres and ROI‐based fractional anisotropy values of both tracts were significantly lower in children with CP than in the comparison group (p<0.05–0.001). Additionally, there was significant negative correlation between GMFCS level and motor–sensory parameters (p<0.001–0.05).

Interpretation  DTI parameters of the CST and PTR in children with CP were significantly lower than in comparison children. In addition, these parameters were significantly correlated with GMFCS level.
Genetic Signatures of Exceptional Longevity in Humans
Authors: Sebastiani Paola , Solovieff Nadia , Puca Annibale , Hartley Stephen W. , Melista Efthymia , Andersen Stacy , Dworkis Daniel A. , Wilk Jemma B. , Myers Richard H. , Steinberg Martin H. , Montano Monty , Baldwin Clinton T. , Perls Thomas T.
Published: July 2010

Healthy aging is thought to reflect the combined influence of environmental factors (lifestyle choices) and genetic factors. To explore the genetic contribution, we undertook a genome-wide association study of exceptional longevity (EL) in 1055 centenarians and 1267 controls. Using these data, we built a genetic model that includes 150 single-nucleotide polymorphisms (SNPs) and found that it could predict EL with 77% accuracy in an independent set of centenarians and controls. Further in silico analysis revealed that 90% of centenarians can be grouped into 19 clusters characterized by different combinations of SNP genotypes—or genetic signatures—of varying predictive value. The different signatures, which attest to the genetic complexity of EL, correlated with differences in the prevalence and age of onset of age-associated diseases (e.g., dementia, hypertension, and cardiovascular disease) and may help dissect this complex phenotype into subphenotypes of healthy aging.
Functional Modules and Structural Basis of Conformational Coupling in Mitochondrial Complex I
Authors: Hunte Carola , Zickermann Volker , Brandt Ulrich
Published: July 2010

Complex I Under Scrutiny

Mitochondrial complex I is a large macromolecular membrane complex that couples electron transfer to proton pumping across the mitochondrial membrane and helps to drive adenosine 5′-triphosphate synthesis.

Hunte
et al.

(p.
448
, published online 1 July) now describe the structure of complex 1 from the aerobic yeast,
Yarrowia lipolytica
. The sites involved in redox chemistry are distant from those that pump protons, and the structure suggests that a 60-angstrom-long helix is involved in transducing energy to the proton-pumping elements.
Peripheral Protein Quality Control Removes Unfolded CFTR from the Plasma Membrane
Authors: Okiyoneda Tsukasa , Barrière Hervé , Bagdány Miklós , Rabeh Wael M. , Du Kai , Höhfeld Jörg , Young Jason C. , Lukacs Gergely L.
Published: July 2010

Peripheral Quality Control

Protein misfolding diseases often lead to the retention and degradation of important proteins within the endoplasmic reticulum (ER). Strategies to reduce the stringency of ER quality control that allow the proteins to carry on through the secretory pathway to reach their destination at the cell surface have shown some promise.

Okiyoneda
et al.

(p.
805
, published online 1 July; see the Perspective by

Hutt and Balch

) wanted to understand how, even if a protein reaches its destination, it may still be subjected to a second level of quality control and be cleared from the plasma membrane. Using functional small-interfering RNA screens in cells expressing the common cystic fibrosis mutation F508CFTR, the authors identified a pair of chaperones that promoted clearance of defective proteins from the plasma membrane. This peripheral quality-control step will also need to be overcome to increase the effectiveness of strategies to overcome protein misfolding disorders.
Soils, geomorphology, landscape evolution, and land use in the Virginia Piedmont and Blue Ridge
Authors: Sherwood W. Cullen , Hartshorn Anthony S. , Eaton L. Scott
Published: July 2010

The object of this field trip is to examine the geology, landforms, soils, and land use in the eastern Blue Ridge and western Piedmont geologic provinces in Orange County in central Virginia. A complex mix of igneous, sedimentary, and metamorphic bedrocks, ranging in age from Mesoproterozoic to Triassic (possibly some Jurassic) underlie the area. Soils are equally varied with a total of 62 series mapped in Orange County alone. The area being relatively stable tectonically, landforms generally reflect the resistance to weathering of the bedrock. Area landforms range from a low ridge over Catoctin greenstone to a gently rolling Triassic basin. Soils examined on the trip represent three orders: Ultisols, Alfisols, and Inceptisols. Residual soils clearly reflect the compositions of the parent rocks and saprolites are common. Map patterns of forested versus nonforested lands bear a striking resemblance to the distribution patterns of the different soil and bedrock types. Our work has shown that the vast majority of the land in central Virginia, even that forested today, shows evidence of past clearing and cultivation. However, the harsh demands of growing tobacco wore out the less fertile and more erodible soils by the mid-nineteenth century resulting in their abandonment and the subsequent regeneration of the vast tracts of hardwood forests we see today. Only the most productive soils remain in agriculture.
Stratigraphy, structure, and tectonics
Authors: Fichter Lynn S. , Whitmeyer Steven J. , Bailey Christopher M. , Burton William
Published: July 2010

This field guide covers a two-day east-to-west transect of the Blue Ridge and Valley and Ridge provinces of northwestern Virginia and eastern West Virginia, in the context of an integrated approach to teaching stratigraphy, structural analysis, and regional tectonics. Holistic, systems-based approaches to these topics incorporate both deductive (stratigraphic, structural, and tectonic theoretical models) and inductive (field observations and data collection) perspectives. Discussions of these pedagogic approaches are integral to this field trip.

Day 1 of the field trip focuses on Mesoproterozoic granitoid basement (associated with the Grenville orogeny) and overlying Neoproterozoic to Early Cambrian cover rocks (Iapetan rifting) of the greater Blue Ridge province. These units collectively form a basement-cored anticlinorium that was thrust over Paleozoic strata of the Valley and Ridge province during Alleghanian contractional tectonics. Day 2 traverses a foreland thrust belt that consists of Cambrian to Ordovician carbonates (Iapetan divergent continental margin), Middle to Upper Ordovician immature clastics (associated with the Taconic orogeny), Silurian to Lower Devonian quartz arenites and carbonates (inter-orogenic tectonic calm), and Upper Devonian to Lower Mississippian clastic rocks (associated with the Acadian orogeny). Alleghanian structural features include the Little North Mountain thrust, Cacapon Mountain anticlinorium, Broad Top synclinorium, and Wills Mountain anticlinorium. Within the road log of this field guide we include both planned and optional stops, so that readers can explore the pedagogic concepts discussed herein in more detail, if desired.
Steel-Based Composites: Driving Forces and Classifications
Authors: Embury David , Bouaziz Olivier
Published: July 2010

In this overview of steel-based composites, consideration is given to conventional metal-matrix composites, in which steel is combined with another metal, ceramic, or polymer. In addition, we define fully steel composites, in which both components of the structure are developed within the steel. These approaches are integrated by discussing a series of macroscopic, mesoscopic, and microscopic examples. This review provides an integrated view of steel composites and allows modeling of the mechanical response to be considered both at the continuum level and in terms of dislocation mechanisms depending on the length scale and the degree of mechanical contrast between the constituent phases. In the context of fully steel composites, consideration is given to static systems in which the volume fraction of the strengthening phase is constant and the length scale is varied by heat treatment or imposed plastic strain. Moreover, we discuss dynamic systems in which a phase transition occurs concomitantly with plastic strain, resulting in an increase in the density of planar barriers that control the plasticity. A discussion of classical works that describe materials such as Damascus steels is used as a template to consider a variety of ways of producing ultrahigh-strength steel composites. Examples of applications are cited and linked to the important issue of developing appropriate fabrication methods for the production of current and future steel composites.
Curcumin prevents cardiac remodeling secondary to chronic renal failure through deactivation of hypertrophic signaling in rats
Authors: Ghosh Siddhartha S. , Salloum Fadi N. , Abbate Antonio , Krieg Richard , Sica Domenic A. , Gehr Todd W. , Kukreja Rakesh C.
Published: July 2010

The prevalence of left ventricular hypertrophy (LVH) is frequent in patients with end-stage renal disease following chronic renal failure (CRF). We investigated the therapeutic efficacy of curcumin, the principal curcuminoid of the Indian curry spice turmeric, in attenuation of LVH and sought to delineate the associated signaling pathways in blunting the hypertrophic response in nephrectomized rats. Adult Sprague-Dawley rats underwent nephrectomy (Nx) by removal of 5/6 of the kidneys. Four groups were studied for 7 wk: 1) control (sham), 2) Nx, 3) Nx + curcumin (150 mg/kg bid), and 4) Nx + enalapril (15 mg/kg bid) as positive control. Subtotal nephrectomy caused renal dysfunction, as evidenced by a gradual increase in proteinuria and elevation in blood urea nitrogen and plasma creatinine. Nx rats showed a significant hypertrophic response and increased diameter of inferior vena cava at inspiration, which was inhibited by treatment with curcumin or enalapril. Moreover, the Nx rats demonstrated changes in the signaling molecules critically involved in the hypertrophic response. These include increased glycogen synthase kinase-3β phosphorylation, β-catenin expression, calcineurin, phosphorylated (p) nuclear factor of activated T cells, pERK, and p-cAMP-dependent kinase. Both curcumin and enalapril variably but effectively deactivated these pathways. Curcumin attenuates cardiac hypertrophy and remodeling in nephrectomized rats through deactivation of multiple hypertrophic signaling pathways. Considering the safety of curcumin, these studies should facilitate future clinical trials in suppressing hypertrophy in patients with CRF.