bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of stochastic motion of bacteria propelled spherical microbeads
Authors: Arabagi Veaceslav , Behkam Bahareh , Cheung Eugene , Sitti Metin
Published: June 2011

This work proposes a stochastic dynamic model of bacteria propelled spherical microbeads as potential swimming microrobotic bodies. Small numbers of S. marcescens bacteria are attached with their bodies to surfaces of spherical microbeads. Average-behavior stochastic models that are normally adopted when studying such biological systems are generally not effective for cases in which a small number of agents are interacting in a complex manner, hence a stochastic model is proposed to simulate the behavior of 8-41 bacteria assembled on a curved surface. Flexibility of the flagellar hook is studied via comparing simulated and experimental results for scenarios of increasing bead size and the number of attached bacteria on a bead. Although requiring more experimental data to yield an exact, certain flagellar hook stiffness value, the examined results favor a stiffer flagella. The stochastic model is intended to be used as a design and simulation tool for future potential targeted drug delivery and disease diagnosis applications of bacteria propelled microrobots.
Transport and magnetic properties of Fe/GaAs Schottky junctions for spin polarimetry applications
Authors: Tereshchenko O. E. , Lamine D. , Lampel G. , Lassailly Y. , Li X. , Paget D. , Peretti J.
Published: June 2011

The electrical, magnetic and spin-filtering properties of Pd/Fe/GaAs(001) junctions are investigated. The Pd/Fe thin layers are deposited on GaAs(001) surfaces both clean and passivated by a thin oxide layer. The surface composition, structure and electronic properties of the starting surfaces are studied by means of XPS, LEED, EELS and photoreflectance. The Fe layer magnetic properties are characterized by magneto-optical Kerr effect (MOKE) measurements, while the electronic properties of the junctions are characterized by current-voltage (I-V) and photoreflectance measurements. For both types of substrate surfaces, the magnetization of the Fe layers is found close to that of a bulk Fe slice of equivalent thickness. For the oxide interface, the I-V curve exhibits almost an ideal Schottkylike behavior, since it can be very well interpreted by the thermoionic equation, using the ideality factor of n = 1.02 and surface barrier ϕb = 0.7 eV. For junctions prepared on the reconstructed GaAs(001) surface, the ideality factor and barrier heights are found in the range of 1.06–1.2 and 0.60–0.75 eV, respectively. Both structures give rise to similar spin filter effects under injection of spin-polarized electrons.
Enhanced small-angle scattering connected to the Widom line in simulations of supercooled water
Authors: Wikfeldt K. T. , Huang C. , Nilsson A. , Pettersson L. G. M.
Published: June 2011

We present extensive simulations on the TIP4P/2005 water model showing significantly enhanced small-angle scattering (SAS) in the supercooled regime. The SAS is related to the presence of a Widom line (TW) characterized by maxima in thermodynamic response functions and Ornstein-Zernike correlation length. Recent experimental small-angle x-ray scattering data [Huang et al., J. Chem. Phys. 133, 134504 (2010)]10.1063/1.3495974 are excellently reproduced, albeit with an increasing temperature offset at lower temperatures. Assuming the same origin of the SAS in experiment and model this suggests the existence of a Widom line also in real supercooled water. Simulations performed at 1000 bar show an increased abruptness of a crossover from dominating high-density (HDL) to dominating low-density (LDL) liquid and strongly enhanced SAS associated with crossing TW, consistent with a recent determination of the critical pressure of TIP4P/2005 at 1350 bar. Furthermore, good agreement with experimental isothermal compressibilities at 1000, 1500, and 2000 bar shows that the high pressure supercooled thermodynamic behavior of water is well described by TIP4P/2005. Analysis of the tetrahedrality parameter Q reveals that the HDL-LDL structural transition is very sharp at 1000 bar, and that structural fluctuations become strongly coupled to density fluctuations upon approaching TW. Furthermore, the tetrahedrality distribution becomes bimodal at ambient temperatures, an observation that possibly provides a link between HDL-LDL fluctuations and the structural bimodality in liquid water indicated by x-ray spectroscopic techniques. Computed x-ray absorption spectra are indeed found to show sensitivity to the tetrahedrality parameter.
Measuring polarizability anisotropies of rare gas diatomic molecules by laser-induced molecular alignment technique
Authors: Minemoto Shinichirou , Sakai Hirofumi
Published: June 2011

The polarizability anisotropies of homonuclear rare gas diatomic molecules, Ar2, Kr2, and Xe2, are investigated by utilizing the interaction of the induced electric dipole moment with a nonresonant, nanosecond laser pulse. The degree of alignment, which depends on the depth of the interaction potential created by the intense laser field, is measured, and is found to increase in order of Ar2, Kr2, and Xe2 at the same peak intensity. Compared with a reference I2 molecule, Ar2, Kr2, and Xe2 are found to have the polarizability anisotropies of 0.45 ± 0.13, 0.72 ± 0.13, and 1.23 ± 0.21 Å3, respectively, where the uncertainties (one standard deviation) in the polarizability anisotropies are carefully evaluated on the basis of the laser intensity dependence of the degree of alignment. The obtained values are compared with recent theoretical calculations and are found to agree well within the experimental uncertainties.
Nonmagnetic B-site substitution induced two-phase coexistence in multiferroic manganites: Monte Carlo simulation
Authors: Tao Y. M. , Qin M. H. , Dong S. , Gao X. S. , Liu J.-M.
Published: June 2011

The influence of B-site nonmagnetic substitution on the spiral spin ordering in multiferroic manganites is investigated by Monte Carlo simulation within the framework of classical Heisenberg model. It is revealed that the nonmagnetic substitution significantly suppressed the multiferroic phase transitions, consistent with experimental results. The boundary between ab-cycloidal phase and bc-cycloidal phase in the temperature-substitution phase diagram becomes faint gradually with increasing substitution level. A coexistence of two cycloidal spin phases is identified when the substitution level surpassed a threshold. The physical origin for the two-phase coexistence induced by the nonmagnetic B-site substitution is discussed.
Neutral gas dynamics in fireballs
Authors: Stenzel R. L. , Ionita C. , Schrittwieser R.
Published: June 2011

Fireballs are local discharge phenomena on positively biased electrodes in partially ionized plasmas. Electrons, energized at a double layer, heat neutral gas which expands. The gas pressure exceeds the plasma pressure, hence becomes important to the stability and transport in fireballs. The flow of gas moves the electrode and sensors similar to a mica pendulum. Flow speed and directions are measured. A fireball gun has been developed to partially collimate the flow of hot gas and heat objects in its path. New applications of fireballs are suggested.
3D-Heisenberg ferromagnetic characteristics in CuCr2Se4
Authors: Zhang Lei , Ling Langsheng , Fan Jiyu , Li Renwen , Tan Shun , Zhang Yuheng
Published: June 2011

The critical properties of the spinel selenide CuCr2Se4 around TC have been investigated by the modified Arrott plot, Kouvel–Fisher method, and critical isotherm analysis. Reliable critical exponents β = 0.372±0.007, γ = 1.277±0.044, and δ = 4.749±0.016 with TC = 430 K are obtained. Based on these critical exponents, the magnetization-field-temperature (M-H-T) data around TC collapses into two independent curves obeying the single scaling equation M(H,ɛ)=ɛβf±(H/ɛβ+γ). Moreover, the critical exponents are confirmed by the field dependence of the magnetic entropy change relation ΔSM|T=TC∝Hn with n = 1 + (β-1)/(β+γ). The obtained critical exponents are in good agreement with the prediction of the 3D-Heisenberg model except that γ is smaller than the theoretical value. The smallness of γ may be due to the delocalization of holes produced by Se1-, which gives evidence for the model of the ferrimagnetic hybridization between localized electrons of the Cr3+ ions and delocalized holes of the Se 4p band proposed for CuCr2Se4.
Epitaxial growth of the high temperature ferromagnetic semiconductor Fe1.5Ti0.5O3 on silicon-compatible substrate
Authors: Hamie Ali , Popova Elena , Dumont Yves , Chikoidze Ekaterina , Warot-Fonrose Bénédicte , Berini Bruno , Keller Niels
Published: June 2011

The ilmenite-hematite (IH) solid solution Fe1.5Ti0.5O3 thin films with rhombohedral symmetry were epitaxially grown on silicon-compatible cubic SrTiO3(001) substrates. Ordered (R-3 symmetry) and disordered (R-3c symmetry) cation arrangement along the film c axis was obtained for different oxygen pressure during the IH growth. Drastic changes in magnetic properties of the films were observed as a function of the cation order. The IH thin films with R-3 symmetry have relatively high conductivity and saturation magnetization at 300 K (6 Ω−1 cm−1 and 0.4 μB/Fe respectively), and Curie temperature of 415 K, making IH a promising material for room-temperature spintronics applications.
Influence of intensity loss in the cavity of a folded Fabry-Perot interferometer on interferometric signals
Authors: Shyu Lih-Horng , Chang Chung-Ping , Wang Yung-Cheng
Published: June 2011

Fabry-Perot interferometer is often used for the micro-displacement, because of its common optical path structure being insensitive to the environmental disturbances. Recently, the folded Fabry-Perot interferometer has been investigated for displacement measurements in large ranges. The advantages of a folded Fabry-Perot interferometer are insensitive to the tilt angle and higher optical resolution. But the design of the optical cavity has become more and more complicated. For this reason, the intensity loss in the cavity will be an important parameter for the distribution of the interferometric intensity. To obtain a more accurate result of such interferometer utilized for displacement measurements, the intensity loss of the cavity in the fabricated folded Fabry-Perot interferometer and the modified equation of the folded Fabry-Perot interferometer will be described. According to the theoretical and experimental results, the presented model is available for the analysis of displacement measurements by a folded Fabry-Perot interferometer.
Observation of phase shifts in a vertical cavity quantum dot switch
Authors: Jin C. Y. , Kojima O. , Kita T. , Wada O. , Hopkinson M.
Published: June 2011

We have studied the possibility to utilize semiconductor quantum dots (QDs) as an optical phase shifter within a vertical geometry for ultrafast information processing. From theoretical analyses, an optical phase nonlinearity in QD structures has been predicted which can be enhanced through the use of an vertical optical cavity. Asymmetric cavity structures with 16/30 periods of GaAs/AlGaAs layers for the front/back mirrors have been fabricated to demonstrate a practical device with significant nonlinear characteristics for optical switching. A phase shift of 18° has been initially observed with a tilted pump scheme. This observation paves the way toward a Mach–Zehnder optical switch using QDs inside a vertical cavity.
Theoretical investigation of kinetics of a Cu2S-based gap-type atomic switch
Authors: Nayak Alpana , Tsuruoka Tohru , Terabe Kazuya , Hasegawa Tsuyoshi , Aono Masakazu
Published: June 2011

Atomic switch, operating by forming and dissolving a metal-protrusion in a nanogap, shows an exponentially large bias dependence and a faster switching with increasing temperature and decreasing off-resistance. These major characteristics are explained with a simple model where the electrochemical potential at the subsurface of solid-electrolyte electrode determines the precipitation rate of metal atoms and the electric-field in the nanogap strongly affects the formation of metal-protrusion. Theoretically calculated switching time, based on this model, well reproduced the measured properties of a Cu2S-based atomic switch as a function of bias, temperature and off-resistance, providing a significant physical insight into the mechanism.
Single InGaN nanodisk light emitting diodes as full-color subwavelength light sources
Authors: Lu Yu-Jung , Lin Hon-Way , Chen Hung-Ying , Yang Yu-Chen , Gwo Shangjr
Published: June 2011

Subwavelength electroluminescent sources with spatial, spectral, and polarization controlling capabilities are critical elements for optical imaging and lithography beyond the diffraction limit. Here, we show that the electroluminescence from single, strain-free InGaN nanodisks embedded in self-assembled GaN p-n nanorods can span the entire visible spectrum with a large linear polarization ratio (∼0.85). Furthermore, this unique nanodisk-in-nanorod geometry enables the realization of the ultrasmall footprint light-emitting diodes (LEDs) to be used as subwavelength light sources. Using these nano-LEDs, we are able to demonstrate near-field, subwavelength photolithography by controlling the exposure time and light intensity from single InGaN nanodisks at chosen wavelengths.
Spectroscopic charge pumping investigation of the amphoteric nature of Si/SiO2 interface states
Authors: Ryan J. T. , Yu L. C. , Han J. H. , Kopanski J. J. , Cheung K. P. , Zhang F. , Wang C. , Campbell J. P. , Suehle J. S.
Published: June 2011

The amphoteric nature of Si/SiO2 interface states in submicron sized metal-oxide-silicon-field-effect-transistors is observed using an enhanced spectroscopic charge pumping method. The method’s simplicity and high sensitivity makes it a powerful tool for interrogating the true nature of electrically measured interface states in samples which exhibit extremely low defect densities. The spectroscopic results obtained clearly illustrate a signature “double peak” density of states consistent with amphoteric Pb center data obtained from electron spin resonance measurements. Since the method is a hybrid of the commonly used charge pumping methodology, it should find widespread use in electronic device characterization.
Impact of carbon coimplantation on boron behavior in silicon: Carbon–boron coclustering and suppression of boron diffusion
Authors: Shimizu Y. , Takamizawa H. , Inoue K. , Toyama T. , Nagai Y. , Okada N. , Kato M. , Uchida H. , Yano F. , Tsunomura T. , Nishida A. , Mogami T.
Published: June 2011

Coimplantation of heterogeneous dopants in materials can be used to control the principal dopant distribution. We used atom probe tomography (APT) and secondary ion mass spectrometry (SIMS) to investigate the impact of coimplanted carbon on boron diffusion in silicon. After annealing, three-dimensional APT analysis of dopant distributions revealed the presence of carbon–boron coclusters around the projection range of boron. In addition, SIMS depth profiles revealed enhanced boron concentration around the projection range of carbon. These results suggest that the carbon–boron interaction suppresses boron diffusion in silicon.
Significant spin polarization of Co2MnGa Heusler thin films on MgO(100) measured by ultraviolet photoemission spectroscopy
Authors: Hahn Michaela , Schönhense Gerd , Jorge Elena Arbelo , Jourdan Martin
Published: June 2011

The spin dependent valence band structure of the Heusler compound Co2MnGa grown on MgO(100) is investigated by spin resolved ultraviolet photoemission spectroscopy (SRUPS). Using a vacuum suitcase, epitaxial thin film samples are transferred from a deposition chamber into an SRUPS chamber with a highly efficient spin detector. The transport results only in weak oxidation of the moderately reactive compound Co2MnGa. A spin polarization of 34% is obtained at the Fermi energy. The energy dependence of the spin polarization including a sign change at E−EF=−0.6 eV is in good agreement with theoretical predictions of the bulk properties of the Heusler compound.
Thermal evaporation furnace with improved configuration for growing nanostructured inorganic materials
Authors: Joanni E. , Savu R. , Valadares L. , Cilense M. , Zaghete M. A.
Published: June 2011

A tubular furnace specifically designed for growing nanostructured materials is presented in this work. The configuration allows an accurate control of evaporation temperature, substrate temperature, total pressure, oxygen partial pressure, volumetric flow and source-substrate distance, with the possibility of performing both downstream and upstream depositions. In order to illustrate the versatility of the equipment, the furnace was used for growing semiconducting oxide nanostructures under different deposition conditions. Highly crystalline indium oxide nanowires with different morphologies were synthesized by evaporating mixtures of indium oxide and graphite powders with different mass ratios at temperatures between 900 ºC and 1050 ºC. The nanostructured layers were deposited onto oxidized silicon substrates with patterned gold catalyst in the temperature range from 600 ºC to 900 ºC. Gas sensors based on these nanowires exhibited enhanced sensitivity towards oxygen, with good response and recovery times.
Finite tunnel magnetoresistance at the compensation point of Sm1−xGdxAl2, a ferromagnetic electrode with zero magnetization
Authors: Da Silva M. , Dumesnil K. , Dufour C. , Hehn M. , Pierre D. , Lacour D. , Montaigne F. , Lengaigne G. , Robert S.
Published: June 2011

A tunnel magnetoresistance effect is observed in magnetic tunnel junctions with an original zero magnetization ferromagnetic electrode composed of Sm1−xGdxAl2. A finite tunnel magnetoresistance is measured when the Sm1−xGdxAl2 electrode is in a magnetic compensated state proving that Sm1−xGdxAl2 with zero magnetization is able to give rise to a spin-polarized current. The temperature dependence of tunnel magnetoresistance reveals that this effect is related to the relative orientation of spin contributions to magnetic moment in both electrodes and that the tunnel polarization of the Sm1−xGdxAl2 electrode is negative.
Novel geminate recombination channel after indirect photoionization of water
Authors: Fischer Martin K. , Rossmadl Hubert , Iglev Hristo
Published: June 2011

We studied the photolysis of neat protonated and heavy water using pump-probe and pump-repump-probe spectroscopy. A novel recombination channel is reported leading to ultrafast quenching (0.7 ± 0.1 ps) of almost one third of the initial number of photo-generated electrons. The efficiency and the recombination rate of this channel are lower in heavy water, 27 ± 5% and (0.9 ± 0.1 ps)−1, respectively. Comparison with similar data measured after photodetachment of aqueous hydroxide provides evidence for the formation of short-lived OH:e− (OD:e−) pairs after indirect photoionization of water at 9.2 eV.
Electrostatic charging and charge transport by hydrated amorphous silica under a high voltage direct current electrical field
Authors: Perles Carlos Eduardo , Volpe Pedro Luiz Onófrio
Published: June 2011

This work was initially based on the casual observation of an electrostatic phenomenon, in which particles of amorphous silica were attracted by a dc electrical field. The first observations were recently shown in a communication in this journal. To explain the electrical charge transport process observed in this work, all forces acting on silica particles were estimated and the significant ones were used to formulate a model made up of three elementary steps. Analyzing the experimental observations using this model, it was possible to suggest that electrons can be introduced into and removed from electronic bands of water.
Reduced leakage current in BiFeO3 thin films with rectifying contacts
Authors: Shuai Yao , Zhou Shengqiang , Streit Stephan , Reuther Helfried , Bürger Danilo , Slesazeck Stefan , Mikolajick Thomas , Helm Manfred , Schmidt Heidemarie
Published: June 2011

BiFeO 3 thin films were grown on Pt/c-sapphire substrates by pulsed laser deposition with different growth rates. With increasing growth rate the leakage current is decreased and the conduction mechanism changes from bulk-limited Poole–Frenkel emission to interface-limited Schottky emission. In the present letter, we show that only the growth rate of the BiFeO3 films close to the metal contacts has to be increased in order to reduce the leakage current and to observe saturated polarization-electric field hysteresis loops.
Synthesis of TiO2 nanoscale rods with MHz femtosecond laser irradiation of single crystal surface and characterisation
Authors: Sivakumar M. , Tan Bo , Venkatakrishnan Krishnan
Published: June 2011

Growth of nanoscale rods on single crystal rutile TiO2 surface irradiated by MHz pulse repetition rate femtosecond laser in nitrogen environment without a catalyst or template is reported. The rods are of 100 nm in width to 1 micron length. Microraman analysis of the laser irradiated surface shows only a decrease in the intensity of active modes as compared to untreated surface. The growth of TiO2 nanorods can be explained by a method combining nanoparticles formation due to expulsion of molten material from laser irradiated spot and their subsequent growth by vapor-liquid-solid process.
Martian icecap hosts a massive CO2 deposit
Authors: Miller Johanna L.
Published: June 2011

Radar data reveal a solid reservoir that contains almost as much carbon dioxide as the planet’s entire atmosphere.
Caribbean Science Foundation sets sail
Authors: Matthews Jermey N. A.
Published: June 2011

Initial investment for the funding agency will come largely from the region’s diaspora scientists, from corporate sponsors, and from development banks.
US budget pact signals end to R&D growth
Authors: Kramer David
Published: June 2011

Additional spending cuts loom as lawmakers consider competing budget blueprints from Obama and the Republicans.
Painting with drops, jets, and sheets
Authors: Herczyński Andrzej , Cernuschi Claude , Mahadevan L.
Published: June 2011

A fluid dynamics analysis of Jackson Pollock’s technique opens his and other artists’ work to quantitative exploration.
The beam business: Accelerators in industry
Authors: Hamm Robert W. , Hamm Marianne E.
Published: June 2011

Particle acceleration techniques originally developed for physics research have found a dazzling variety of uses in manufacturing and commerce.
Bees, Beekeepers, and Bureaucrats: Parasitism and the Politics of Transgenic Life
Authors: Lezaun Javier
Published: June 2011

Over the last decade the flying patterns and foraging behavior of bees have become a matter of public policy in the European Union. Determined to establish a system where transgenic crops can ‘coexist’ with conventional and organic farming, the EU has begun to erect a system of demarcations and separations designed to minimize the extent of ‘gene flow’ from genetically modified plants. As the European landscape is regimented through the introduction of isolation distances and buffer zones, bees and other pollinating insects have become vectors of ‘genetic pollution’, disrupting the project of cohabitation and purification devised by European authorities. Drawing on the work of Michel Serres on parasitism, this paper traces the emergence of bees as an object of regulatory scrutiny and as an interruptor of the ‘coexistence’ project. Along with bees, however, another uninvited guest arrived unexpectedly on the scene: The beekeeper, who came to see his traditional relationship to bees, crops, and consumers at risk. The figure of the parasite connects the two essential dynamics described in this paper: an escalation of research and the intensification of political attributes.
Generation of a unique small molecule peptidomimetic that neutralizes lupus autoantibody activity
Authors: Bloom Ona , Cheng Kai Fan , He Mingzhu , Papatheodorou Angelos , Volpe Bruce T. , Diamond Betty , Al-Abed Yousef
Published: June 2011

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the presence of pathogenic autoantibodies, many of which are directed against nuclear antigens, in particular double-stranded (ds) DNA. Both clinical studies and animal models have shown that anti-dsDNA antibodies contribute to kidney disease, which is present in 50% of lupus patients and is a major cause of mortality. We previously demonstrated that a subset of nephrotoxic anti-dsDNA antibodies also recognizes the pentapeptide consensus sequence D/E W D/E Y S/G (DWEYS) present in the NR2A and NR2B subunits of theN-methyl-d-aspartate receptor (NMDAR). Autoantibodies with this specificity are present in ≈40% of lupus patient sera and are both nephrotoxic and neurotoxic. Elevated titers are present in cerebrospinal fluid of patients with central nervous system manifestations of SLE. Administration of the nonnaturally occurring D form of the DWEYS pentapeptide prevents these antibodies from depositing in glomeruli and from mediating neuronal excitotoxicity. To craft a more useful therapeutic, we used the structural features of the DWEYS peptide to design a unique, selective, and potent small molecule peptidomimetic, FISLE-412, which neutralizes anti-dsDNA/NMDAR lupus autoantibodies and prevents their pathogenic interaction with tissue antigens. This compound, or others derived from it, may provide a unique strategy for the development of lupus therapeutics.
Genetic Structure, Evolutionary History, and Conservation Units of Bull Trout in the Coterminous United States
Authors: Ardren William R. , DeHaan Patrick W. , Smith Christian T. , Taylor Eric B. , Leary Robb , Kozfkay Christine C. , Godfrey Lindsay , Diggs Matthew , Fredenberg Wade , Chan Jeffrey , Kilpatrick C. William , Small Maureen P. , Hawkins Denise K.
Published: June 2011

The bull trout Salvelinus confluentus is a broadly distributed char in northwestern North America that has undergone significant population declines. This species is currently protected under the Endangered Species Act across its range in the coterminous United States. To clarify patterns of phylogenetic structure and to assist with identification of conservation units, we examined genetic variation within and among 75 representative bull trout populations sampled throughout the USA. Genealogies from a 520‐base‐pair portion of the mitochondrially encoded NADH dehydrogenase 1 gene (ND‐1) revealed reciprocal monophyly between coastal and interior lineages that differed by 1.34% in DNA sequence. The geographic distribution of the two lineages was divided by the Cascade Mountains, a pattern that likely reflects postglacial dispersal from separate glacial refugia. Analysis of microsatellite variation revealed that 76% of populations had an estimated effective population size less than 50 and indicated high divergence among populations caused by genetic drift (average genetic differentiation index FST = 0.32) and mutation (average genetic differentiation index RST = 0.58). Concordant phylogeographic and phylogenetic patterns observed with microsatellite and mitochondrial DNA analyses provided evidence for two to six bull trout lineages that largely reflect historic patterns of gene flow and isolation among populations. These lineages can be further subdivided into finer‐scale units due to the extremely low dispersal among populations and small effective population sizes. In fact, Bayesian analysis of population structure identified an optimal solution of 69 genetically different groups. Based on these results, we believe that conservation efforts should ideally be focused on the 118 bull trout core areas originally identified in the draft Endangered Species Act recovery plan, which are broadly defined as metapopulations. We provide examples of how other data, such as unique life history forms and ecological setting, can be used in combination with our genetic results to refine the U.S. Fish and Wildlife Service's hierarchical conservation strategy for bull trout.
New ways to turn on NKT cells
Authors: Godfrey Dale Ian , Rossjohn Jamie
Published: June 2011

Natural killer T (NKT) cells are CD1d-restricted, lipid antigen–reactive T cells with powerful immunoregulatory potential. The prototypic antigen for NKT cells is a marine sponge–derived glycolipid, α-galactosylceramide (α-GalCer), but this is not normally encountered in the mammalian environment. Thus, there is great interest in the identification of more physiological stimuli for NKT cells, and numerous studies have shown that NKT cells are capable of responding to a range of microbial lipid-based antigens. Two new studies expand our understanding of environmental NKT cell stimuli, with one showing that CD1d-restricted NKT cell antigens are present within common house dust extract (HDE), whereas the other shows that NKT cells can respond to innate stimuli irrespective of the presence of foreign microbial antigens. Collectively, these two investigations indicate that NKT cells are far more likely to encounter foreign antigens, or innate activating signals, than previously recognized, suggesting a more central role for these cells in the immune system.
A note on the join property
Authors: Lewis Andrew
Published: June 2011

A Turing degree

a
\boldsymbol {a}

satisfies the join property if, for every non-zero

b
>
a

\boldsymbol {b}>\boldsymbol {a}

, there exists

c
>
a

\boldsymbol {c}>\boldsymbol {a}

with

b
∨
c
=
a

\boldsymbol {b} \vee \boldsymbol {c}= \boldsymbol {a}

. It was observed by Downey, Greenberg, Lewis and Montalbán that all degrees which are non-GL

2

_2

satisfy the join property. This, however, leaves open many questions. Do all a.n.r. degrees satisfy the join property? What about the PA degrees or the Martin-Löf random degrees? A degree

b
\boldsymbol {b}

satisfies the cupping property if, for every

a
>
b

\boldsymbol {a}>\boldsymbol {b}

, there exists

c
>
a

\boldsymbol {c}>\boldsymbol {a}

with

b
∨
c
=
a

\boldsymbol {b}\vee \boldsymbol {c}=\boldsymbol {a}

. Is satisfying the cupping property equivalent to all degrees above satisfying join? We answer all of these questions by showing that above every low degree there is a low degree which does not satisfy join. We show, in fact, that all low fixed point free degrees

a
\boldsymbol {a}

fail to satisfy join and, moreover, that the non-zero degree below

a
\boldsymbol {a}

without any joining partner can be chosen to be a c.e. degree.
Convex integration for a class of active scalar equations
Authors: Shvydkoy R.
Published: June 2011

We show that a general class of active scalar equations, including porous media and certain magnetostrophic turbulence models, admits non-unique weak solutions in the class of bounded functions. The proof is based upon the method of convex integration recently implemented for equations of fluid dynamics.
Melampsora larici-populina Transcript Profiling During Germination and Timecourse Infection of Poplar Leaves Reveals Dynamic Expression Patterns Associated with Virulence and Biotrophy
Authors: Duplessis Sébastien , Hacquard Stéphane , Delaruelle Christine , Tisserant Emilie , Frey Pascal , Martin Francis , Kohler Annegret
Published: June 2011

Melampsora larici-populina is responsible for poplar leaf rust disease and causes severe epidemics in poplar plantations in Europe. The poplar rust genome has been recently sequenced and, in order to find the genetic determinants associated with its biotrophic lifestyle, we generated a whole-genome custom oligoarray and analyzed transcript profiles of M. larici-populina during the infection timecourse in poplar leaves. Different stages were investigated during the asexual development of the rust fungus, including resting and germinating urediniospores and seven in planta stages in the telial host. In total, 76% of the transcripts were detected during leaf infection as well as in urediniospores, whereas 20% were only detected in planta, including several transporters and many small secreted proteins (SSP). We focused our analysis on gene categories known to be related to plant colonization and biotrophic growth in rust pathogens, such as SSP, carbohydrate active enzymes (CAZymes), transporters, lipases, and proteases. Distinct sets of SSP transcripts were expressed all along the infection process, suggesting highly dynamic expression of candidate rust effectors. In contrast, transcripts encoding transporters and proteases were mostly expressed after 48 h postinoculation, when numerous haustoria are already formed in the leaf mesophyll until uredinia formation, supporting their role in nutrient acquisition during biotrophic growth. Finally, CAZymes and lipase transcripts were predominantly expressed at late stages of infection, highlighting their importance during sporulation.
Quark confinement and the renormalization group
Authors: Ogilvie Michael C.
Published: June 2011

Recent approaches to quark confinement are reviewed, with an emphasis on their connection to renormalization group (RG) methods. Basic concepts related to confinement are introduced: the string tension, Wilson loops and Polyakov lines, string breaking, string tension scaling laws, centre symmetry breaking and the deconfinement transition at non-zero temperature. Current topics discussed include confinement on
R
3
×
S
1
, the real-space RG, the functional RG and the Schwinger–Dyson equation approach to confinement.
The density-matrix renormalization group: a short introduction
Authors: Schollwöck Ulrich
Published: June 2011

The density-matrix renormalization group (DMRG) method has established itself over the last decade as the leading method for the simulation of the statics and dynamics of one-dimensional strongly correlated quantum lattice systems. The DMRG is a method that shares features of a renormalization group procedure (which here generates a flow in the space of reduced density operators) and of a variational method that operates on a highly interesting class of quantum states, so-called matrix product states (MPSs). The DMRG method is presented here entirely in the MPS language. While the DMRG generally fails in larger two-dimensional systems, the MPS picture suggests a straightforward generalization to higher dimensions in the framework of tensor network states. The resulting algorithms, however, suffer from difficulties absent in one dimension, apart from a much more unfavourable efficiency, such that their ultimate success remains far from clear at the moment.
Renormalization group aspects of graphene
Authors: Vozmediano María A. H.
Published: June 2011

Graphene is a two-dimensional crystal of carbon atoms with fascinating electronic and morphological properties. The low-energy excitations of the neutral, clean system are described by a massless Dirac Hamiltonian in (2+1) dimensions, which also captures the main electronic and transport properties. A renormalization group analysis sheds light on the success of the free model: owing to the special form of the Fermi surface that reduces to two single points in momentum space, short-range interactions are irrelevant and only gauge interactions such as long-range Coulomb or effective disorder can play a role in the low-energy physics. We review these features and briefly discuss other aspects related to disorder and to the bilayer material along the same lines.
Renormalization group for non-relativistic fermions
Authors: Shankar R.
Published: June 2011

A brief introduction is given to the renormalization group for non-relativistic fermions at finite density. It is shown that Landau’s theory of the Fermi liquid arises as a fixed point (with the Landau parameters as marginal couplings) and its instabilities as relevant perturbations. Applications to related areas, nuclear matter, quark matter and quantum dots, are briefly discussed. The focus will be on explaining the main ideas to people in related fields, rather than addressing the experts.
Renormalization group flow equations with full momentum dependence
Authors: Blaizot Jean-Paul
Published: June 2011

After a short elementary introduction to the exact renormalization group for the effective action, I discuss a particular truncation of the hierarchy of flow equations that allows for the determination of the full momentum of the
n
-point functions. Applications are then briefly presented, to critical
O
(
N
) models, to Bose–Einstein condensation and to finite-temperature field theory.
Functional renormalization for the Bardeen–Cooper–Schrieffer to Bose–Einstein condensation crossover
Authors: Scherer Michael M. , Floerchinger Stefan , Gies Holger
Published: June 2011

We review the functional renormalization group (RG) approach to the Bardeen–Cooper–Schrieffer to Bose–Einstein condensation (BCS–BEC) crossover for an ultracold gas of fermionic atoms. Formulated in terms of a scale-dependent effective action, the functional RG interpolates continuously between the atomic or molecular microphysics and the macroscopic physics on large length scales. We concentrate on the discussion of the phase diagram as a function of the scattering length and the temperature, which is a paradigm example for the non-perturbative power of the functional RG. A systematic derivative expansion provides for both a description of the many-body physics and its expected universal features as well as an accurate account of the few-body physics and the associated BEC and BCS limits.
Renormalization group and the Planck scale
Authors: Litim Daniel F.
Published: June 2011

I discuss the renormalization group approach to gravity, and its link to Weinberg’s asymptotic safety scenario, and give an overview of results with applications to particle physics and cosmology.
New applications of the renormalization group method in physics: a brief introduction
Authors: Meurice Y. , Perry R. , Tsai S.-W.
Published: June 2011

The renormalization group (RG) method developed by Ken Wilson more than four decades ago has revolutionized the way we think about problems involving a broad range of energy scales such as phase transitions, turbulence, continuum limits and bifurcations in dynamical systems. The Theme Issue provides articles reviewing recent progress made using the RG method in atomic, condensed matter, nuclear and particle physics. In the following, we introduce these articles in a way that emphasizes common themes and the universal aspects of the method.
Rituximab monotherapy with eight weekly infusions for relapsed or refractory patients with indolent B cell non‐Hodgkin lymphoma mostly pretreated with rituximab: A multicenter phase II study
Authors: Tobinai Kensei , Igarashi Tadahiko , Itoh Kuniaki , Kurosawa Mitsutoshi , Nagai Hirokazu , Hiraoka Akira , Kinoshita Tomohiro , Uike Naokuni , Ogura Michinori , Nawano Shigeru , Mori Shigeo , Ohashi Yasuo ,   the IDEC‐C2B8 Study Group
Published: June 2011

Information regarding rituximab monotherapy with eight weekly infusions for relapsed or refractory indolent B cell non‐Hodgkin lymphoma (B‐NHL), in particular for patients pretreated with rituximab, is limited. To evaluate the efficacy and safety of eight doses of rituximab monotherapy, 52 patients with relapsed or refractory indolent B‐NHL were enrolled in the present study. Forty of 45 eligible patients (89%) had follicular lymphoma and 24 (53%) were at intermediate or high risk group according to the Follicular Lymphoma International Prognostic Index. The median number of prior chemotherapy regimens was 1 (range 1–7). At the median follow‐up of 12.2 months, the overall response rate (ORR), complete response rate (%CR), and median progression‐free survival (PFS) were 69% (95% confidence interval [CI] 53%–82%), 47% (95% CI 32%–62%), and 15.6 months (95% CI 10.6– months), respectively. In the 33 patients pretreated with rituximab, the ORR, %CR, and median PFS were inferior compared with values for the 12 patients who had not received rituximab previously (64%vs 83% for ORR; 39%vs 67% for %CR; and 13.8 vs 17.5 months for median PFS, respectively). All mild‐to‐moderate infusion‐related toxicities were reversible. Grade 3/4 non‐hematologic adverse events occurred in six of the 52 patients. Two patients developed Grade 4 late‐onset neutropenia and a decrease (>50%) in serum immunoglobulin was observed in six patients. In conclusion, rituximab monotherapy with eight weekly infusions is effective in relapsed patients with indolent B‐NHL, with acceptable toxicities, including in patients pretreated with rituximab; however, careful monitoring is recommended for infections associated with late‐onset neutropenia and hypogammaglobulinemia. (University Hospital Medical Information Network no. UMIN000002974.) (Cancer Sci 2011; 102: 1698–1705)
Adalimumab sustains steroid‐free remission after 3 years of therapy for Crohn’s disease
Authors: Kamm M. A. , Hanauer S. B. , Panaccione R. , Colombel J.‐F. , Sandborn W. J. , Pollack P. F. , Zhou Q. , Robinson A. M.
Published: June 2011

Aliment Pharmacol Ther 2011; 34: 306–317

Background  Treatments that achieve sustainable steroid‐free clinical remission in Crohn’s disease are needed; however, long‐term steroid‐sparing efficacy data are limited.

Aim  To evaluate steroid‐sparing efficacy and the impact of steroid discontinuation on adverse events during treatment of Crohn's disease with adalimumab in the phase III randomised, double‐blind 1‐year CHARM trial and for an additional 2 years in its open‐label extension ADHERE.

Methods  Steroid‐free remission and response and steroid‐sparing (≥50% steroid dose reduction) remission rates were evaluated over 3 years in patients who were taking corticosteroids at CHARM baseline.

Results  Of 778 patients randomised in CHARM (including those who did not achieve clinical response to open‐label induction therapy), 313 patients (40%) were on corticosteroids at baseline. In the 206 patients randomised to adalimumab, rates of steroid‐free remission at 1 year and 3 years were 26% and 23% respectively; corresponding rates were 29% and 25% for steroid‐sparing remission and 32% and 28% for steroid‐free response. Although the incidence of serious infections with adalimumab treatment during CHARM was higher in patients taking steroids at baseline than those who were not, the rates of overall adverse events, serious infections and opportunistic infections were lower in patients who were able to discontinue corticosteroids than those who remained on steroids.

Conclusion  Adalimumab therapy resulted in modest but clinically meaningful rates of steroid‐free remission, sustained over 3 years of treatment, in a heavily pretreated population of patients with Crohn's disease receiving steroids at the start of therapy (http://www.clinicaltrials.gov number: NCT00077779).
Plasma IL‐6 concentration correlates with clinical disease activity and serum C‐reactive protein concentration in chronic urticaria patients
Authors: Kasperska‐Zajac A. , Sztylc J. , Machura E. , Jop G.
Published: June 2011

Background Our previous study was the first to demonstrate enhanced plasma IL‐6 concentrations in chronic urticaria (CU). It is known that C‐reactive protein (CRP) is a sensitive marker of an underlying systemic inflammation, triggered mainly as a response to IL‐6.

Objective To evaluate plasma IL‐6 concentration in CU patients relating to the clinical disease activity and serum CRP concentration.

Methods Serum CRP and plasma IL‐6 concentrations were measured in 58 CU patients and 30 healthy subjects. Ten CU patients were evaluated twice, during the active period as well as upon the spontaneous clinical remission of the disease. CU activity was assessed with the use of the symptom scores recommended by EAACI/GALEN/EDF guidelines.

Results IL‐6 and CRP concentrations were significantly increased in CU patients as compared with the healthy subjects, whereas they decreased remarkably upon the spontaneous remission. IL‐6 concentration was associated with weekly urticaria activity scores and also significant differences were found between patients showing different degrees of urticarial activity. Significant correlation was observed between IL‐6 and CRP concentrations.

Conclusions and Clinical Relevance This study reinforces evidence that, apart from a local cutaneous inflammation, CU is associated with a systemic inflammatory response. Such acute‐phase response is manifested by increased circulating IL‐6, which varies along with CRP changes and may be related to the urticarial activity.

Cite this as: A. Kasperska‐Zajac, J. Sztylc, E. Machura and G. Jop, Clinical & Experimental Allergy, 2011 (41) 1386–1391.
Basic mechanisms of itch
Authors: Potenzieri C. , Undem B. J.
Published: June 2011

Chronic itch represents a burdensome clinical problem that can originate from a variety of aetiologies. Pruriceptive itch originates following the activation of peripheral sensory nerve endings following damage or exposure to inflammatory mediators and ascends to the brain through the spinal thalamic tract. Much insight has been gained into the understanding of the mechanisms underlying pruriceptive itch through studies using humans and experimental animals. More than one sensory nerve subtype is thought to subserve pruriceptive itch which includes both unmyelinated C‐fibres and thinly myelinated Aδ nerve fibres. There are a myriad of mediators capable of stimulating these afferent nerves leading to itch, including biogenic amines, proteases, cytokines, and peptides. Some of these mediators can also evoke sensations of pain and the sensory processing underlying both sensations overlaps in complex ways. Studies have demonstrated that both peripheral and central sensitization to pruritogenic stimuli occur during chronic itch.

Cite this as: C. Potenzieri and B. J. Undem, Clinical & Experimental Allergy, 2012 (42) 8–19.
Unacylated ghrelin is associated with changes in insulin sensitivity and lipid profile during an exercise intervention
Authors: Cederberg Henna , Koivisto Vesa‐Matti , Jokelainen Jari , Surcel Heljä‐Marja , Keinänen‐Kiukaanniemi Sirkka , Rajala Ulla
Published: June 2011

Objective  Ghrelin has been implicated in energy homeostasis, body weight regulation and glucose metabolism. Level of unacylated ghrelin (UAG), but not acylated ghrelin (AG), has been suggested to increase during long‐term exercise. However, the association of the level of UAG with exercise‐induced changes of insulin sensitivity and lipid metabolism has not been previously investigated. We hypothesized that an increase in UAG level in response to a long‐term exercise programme improves insulin sensitivity and associated lipid profile, independently of weight loss.

Design, patients and measurements  A prospective study of 552 young men (mean age 19·3 and range 19–28 years) undergoing military service with structured 6‐month exercise training programme. Exercise performance, clinical and biochemical measurements were obtained at baseline and follow‐up. Association between UAG level and fasting glucose, insulin, insulin sensitivity and lipid levels were evaluated.

Results  An overall increase in the level of UAG was observed during the 6‐month follow‐up (P < 0·001), which was largest among those with weight loss ≥ 2·5% or among those whose reduction in waist circumference was largest (P = 0·007 and P < 0·001, respectively). A change in UAG level correlated inversely with a change in fasting glucose and insulin levels, HOMA‐IR, total cholesterol and total triglyceride levels (P < 0·001 for all). The association between change in the UAG level and the change in insulin sensitivity was independent of weight loss or reduction in waist circumference.

Conclusions  Increase in UAG level was associated with improved insulin sensitivity via mechanisms independent of weight loss during an intensive, long‐term exercise intervention in young healthy men.