bluuebunny/crossref_metadata_2025 huggingface dataset:
Katarakt – Grauer Star
Authors: Stürmer Jörg
Published: March 2009

Die Katarakt ist die häufigste Erblindungsursache weltweit (20 Millionen Blinde/Sehbehinderte). Die häufigste Form der Katarakt ist die altersabhängige Katarakt. Die einzige mögliche Behandlung ist die Operation, die in den industrialisierten Ländern die häufigste Operation überhaupt darstellt. Indikation für eine Kataraktoperation ist, dass die Sehkraft den Bedürfnissen des Patienten nicht mehr entspricht. Die heutige Operationstechnik ist die Verflüssigung des harten Anteils der getrübten Linse mittels Phakoemulsifikation und die Implantation einer faltbaren Kunstlinse durch einen < 3 mm groβen selbstdichtenden Schnitt. Bei einem Groβteil der Patienten kann diese Operation ambulant in Lokalanästhesie (meist Tropfen) durchgeführt werden. Schwere Komplikationen sind selten (< 1%), können aber im Extremfall zum Verlust der Sehkraft führen (< 1‰). Neue Entwicklungen spielen sich heute praktisch ausschlieβlich im Bereich des Designs und von Zusatzfunktionen der Intraokularlinsen ab.
Wissenswertes aus der Neuro-Ophthalmologie
Authors: Landau Klara
Published: March 2009

Als interdisziplinäres Gebiet zwischen der Augenheilkunde und der Neurologie befasst sich die Neuro-Ophthalmologie mit Erkrankungen, welche das afferente oder das efferente visuelle System betreffen und deren Urachen im weitesten Sinn in Funktionsstörungen des Nervensystems liegen. Das sich immer weiter entwickelnde Instrumentarium der bildgebenden Verfahren und deren breite Verfügbarkeit erleichtern in der Regel die Diagnostik. Trotz dieser enormen technischen Fortschritte spielt die Kenntnis der Symptome und der klinischen Befunderhebung eine entscheidende Rolle, um zielgerichtet und patientengerecht zur richtigen Diagnose zu kommen und die best mögliche Therapie einzuleiten. In der nachfolgenden Abhandlung werden die in der Praxis relevanten neuroophthalmologischen Krankheitsbilder vor allem im Hinblick auf das initiale Management und die Indikation und Dringlichkeit der Zuweisung in eine spezialisierte Klinik beleuchtet.
Chronische Kreuzschmerzen – Ein gefürchteter Circulus vitiosus!
Authors: Gautschi  , Cadosch  , Bauer  , Land  , Fournier  , Hildebrandt
Published: March 2009

Bei bis zu 10% der Patienten mit «Low Back Pain» kommt es zu chronischen Kreuzschmerzen, welche per definitionem über einen Zeitraum von mindestens drei Monaten bestehen. Dieses Krankheitsbild hat gravierende Auswirkungen auf die psycho-soziale und physische Integrität der betroffenen Personen. Schmerzsyndrome der Lendenwirbelsäule verursachen jährlich direkte und indirekte Kosten von 150–250 Milliarden Schweizer Franken. Trotz intensiver Behandlung bleiben einige Patienten symptomatisch. Daraus resultiert eine beschwerdebedingte funktionelle Unterbelastung, welche zu einer Verminderung der Leistungsfähigkeit und einer verstärkten Inaktivität führt – der Beginn eines Teufelskreislaufs. Ein multimodales Behandlungskonzept mit physio- und psychotherapeutischer Behandlung, welches von einer gezielten medikamentösen Therapie unterstützt wird, verbessert die körperlichen Funktionen und bewirkt eine deutliche Beschwerdereduktion. Bei länger andauernder Therapieresistenz ist es sinnvoll, frühzeitig minimal-invasive oder invasive Therapieoptionen in Erwägung zu ziehen.
Empirical orthogonal function analysis of the diurnal cycle of precipitation in a multi‐scale climate model
Authors: Pritchard Michael S. , Somerville Richard C. J.
Published: March 2009

Long‐term variability in the hydrologic cycle is poorly simulated by current generation global climate models (GCMs), partly due to known climatological biases at shorter timescales. We demonstrate that a prototype Multi‐scale Modeling Framework (MMF) provides a superior representation of the spatial and temporal structure of precipitation at diurnal timescales than a GCM. Results from empirical orthogonal function (EOF) decomposition of the boreal summer climatological composite diurnal cycle of precipitation in an MMF are compared to a GCM and satellite data from the Tropical Rainfall Measuring Mission. The eigenspectrum, principal component time series, and the spatial structure of leading EOFs in an eigenmode decomposition of the MMF composite day are a much better match to observations than the GCM. Regional deficiencies in the MMF diurnal cycle are manifest as localized anomalies in the spatial structures of the first two leading EOFs.
Satellite microwave observations of the interannual variability of snowmelt on sea ice in the Southern Ocean
Authors: Willmes Sascha , Haas Christian , Nicolaus Marcel , Bareiss Jörg
Published: March 2009

Snowmelt processes on Antarctic sea ice are examined. We present a simple snowmelt indicator based on diurnal brightness temperature variations from microwave satellite data. The method is validated through extensive field data from the western Weddell Sea and lends itself to the investigation of interannual and spatial variations of the typical snowmelt on Antarctic sea ice. We use in‐situ measurements of physical snow properties to show that despite the absence of strong melting, the summer period is distinct from all other seasons with enhanced diurnal variations of snow wetness. A microwave emission model reveals that repeated thawing and refreezing cause the typical microwave emissivity signatures that are found on perennial Antarctic sea ice during summer. The proposed melt indicator accounts for the characteristic phenomenological stages of snowmelt in the Southern Ocean and detects the onset of diurnal snow wetting. An algorithm is presented to map large‐scale snowmelt onset based on satellite data from the period between 1988 and 2006. The results indicate strong meridional gradients of snowmelt onset with the Weddell, Amundsen, and Ross Seas showing earliest (beginning of October) and most frequent snowmelt. Moreover, a distinct interannual variability of melt onset dates and large areas of first‐year ice where no diurnal freeze thawing occurs at the surface are determined.
Analysis of the summertime buildup of tropospheric ozone abundances over the Middle East and North Africa as observed by the Tropospheric Emission Spectrometer instrument
Authors: Liu Jane J. , Jones Dylan B. A. , Worden John R. , Noone David , Parrington Mark , Kar Jay
Published: March 2009

We use the GEOS‐Chem chemical transport model to interpret observations of tropospheric ozone from the Tropospheric Emission Spectrometer (TES) satellite instrument in summer 2005. Observations from TES reveal elevated ozone in the middle troposphere (500–400 hPa) across North Africa and the Middle East. Observed ozone abundances in the middle troposphere are at a maximum in summer and a minimum in winter, consistent with the previously predicted summertime “Middle East ozone maximum.” This summertime enhancement in ozone is associated with the Arabian and Sahara anticyclones, centered over the Zagros and Atlas Mountains, respectively. These anticyclones isolate the middle troposphere over northeast Africa and the Middle East, with westerlies to the north and easterlies to the south, facilitating the buildup of ozone. Over the Middle East, we find that in situ production and transport from Asia provides comparable contributions of 30–35% to the ozone buildup. Over North Africa, in situ production is dominant (at about 20%), with transport from Asia, North America, and equatorial Africa each contributing about 10–15% to the total ozone. We find that although the eastern Mediterranean is characterized by strong descent in the middle and upper troposphere in summer, transport from the boundary layer accounts for about 25% of the local Middle Eastern contribution to the ozone enhancement in the middle troposphere. This upward transport of boundary layer air is associated with orographic lifting along the Zagros Mountains in Iran and the Asir and Hijaz Mountain ranges in Saudi Arabia, and is consistent with TES observations of deuterated water.
Chlorella virus ATCV-1 encodes a functional potassium channel of 82 amino acids
Authors: Gazzarrini Sabrina , Kang Ming , Abenavoli Alessandra , Romani Giulia , Olivari Claudio , Gaslini Daniele , Ferrara Giuseppina , van Etten James L. , Kreim Michael , Kast Stefan M. , Thiel Gerhard , Moroni Anna
Published: March 2009

Chlorella virus PBCV-1 (Paramecium bursaria chlorella virus-1) encodes the smallest protein (94 amino acids, named Kcv) previously known to form a functional K+ channel in heterologous systems. In this paper, we characterize another chlorella virus encoded K+ channel protein (82 amino acids, named ATCV-1 Kcv) that forms a functional channel in Xenopus oocytes and rescues Saccharomyces cerevisiae mutants that lack endogenous K+ uptake systems. Compared with the larger PBCV-1 Kcv, ATCV-1 Kcv lacks a cytoplasmic N-terminus and has a reduced number of charged amino acids in its turret domain. Despite these deficiencies, ATCV-1 Kcv accomplishes all the major features of K+ channels: it assembles into a tetramer, is K+ selective and is inhibited by the canonical K+ channel blockers, barium and caesium. Single channel analyses reveal a stochastic gating behaviour and a voltage-dependent conductance that resembles the macroscopic I/V relationship. One difference between PBCV-1 and ATCV-1 Kcv is that the latter is more permeable to K+ than Rb+. This difference is partially explained by the presence of a tyrosine residue in the selective filter of ATCV-1 Kcv, whereas PBCV-1 Kcv has a phenylalanine. Hence, ATCV-1 Kcv is the smallest protein to form a K+ channel and it will serve as a model for studying structure–function correlations inside the potassium channel pore.
High-resolution and high-coercivity FePtL1 magnetic force microscopy nanoprobes to study next-generation magnetic recording media
Authors: Amos Nissim , Lavrenov Andrey , Fernandez Robert , Ikkawi Rabee , Litvinov Dmitri , Khizroev Sakhrat
Published: March 2009

A cylindrical probe with almost perfectly flat plateaulike surface was focused ion beam (FIB) milled from an atomic force microscopy probe in order to create the required surface conditions for thin film deposition with finely controlled deposition/growth parameters. A composition of Pd(5 nm)/MgO(8 nm)/FePt(10 nm)/MgO(8 nm) was sputter deposited on the plateau probe, followed by deposition of a Pd (5 nm) protective layer. The plateau probe was then FIB-milled to produce a tip with a curvature radius of ∼25 nm. After annealing the probe at 650 °C for ∼15 min to generate an ultrahigh anisotropy L10 phase, magnetic force microscopy (MFM) imaging was performed with the probe on magnetic tracks with linear densities ranging from 200 to 1200 KFCI. The results show sub-20-nm lateral resolution in ambient conditions and magnetic tracks, which are otherwise invisible to standard MFM probes, are clearly evident with the FIB-fabricated FePt probe. With relatively high spatial resolution and coercivity values higher than 1 T, among other applications, this type of probe may be ideal for high-quality MFM study of next-generation recording media.
Layer resolved magnetization dynamics in coupled magnetic films using time-resolved x-ray magnetic circular dichroism with continuous wave excitation
Authors: Martin T. , Woltersdorf G. , Stamm C. , Dürr H. A. , Mattheis R. , Back C. H. , Bayreuther G.
Published: March 2009

Time-resolved x-ray magnetic circular dichroism was used to investigate ferromagnetically coupled CoFe/Ru/NiFe bilayers. The magnetization dynamics was driven by a continuous wave excitation. The precessional motion of the individual layers was detected separately by tuning the x-ray photon energy to the L3 absorption edge of either Ni or Co. Using two different waveguide stack geometries in-phase and antiphase excitation could be selected showing its effect in the measured precessional signal of the individual layers. In exchange-coupled bilayer two precessional modes were observed for each layer. The relative phase angles of the magnetic response between the two layers were found to be 8° and 133°, for the two modes revealed their quasiacoustic and quasioptic character.
Nonlithographic fabrication of 25 nm magnetic nanodot arrays with perpendicular anisotropy over a large area
Authors: Rahman M. Tofizur , Shams Nazmun N. , Lai Chih-Huang
Published: March 2009

A simple method is demonstrated to fabricate 25 nm magnetic nanodot arrays with perpendicular anisotropy over 10 cm2 coverage area. The nanodot arrays are fabricated by depositing Co/Pt multilayers (MLs) onto the SiO2 dot arrays formed on a Si wafer. At first, arrays of the SiO2 dots are fabricated on a Si wafer by anodizing a thin Al film deposited on it. The SiO2 dots are formed at the base of the anodized alumina (AAO) pores due to the selective oxidation of the Si through the AAO pores during over anodization of the Al film. The average diameter, periodicity, and height of the SiO2 dots are about 24, 43, and 17 nm, respectively. Then {Co(0.4 nm)/Pt(0.08 nm)}8 MLs with a 3 nm Pt buffer layer is deposited onto the SiO2 dot arrays by sputtering. The average diameter and periodicity of the Co/Pt nanodot arrays are 25.4 and 43 nm, respectively, with narrow distribution. The nanodot arrays exhibit strong perpendicular anisotropy with a squareness ratio of unity and negative nucleation fields. The coercivity of the nanodot arrays is about one order higher than that of the continuous film, i.e., the same structure deposited on the SiO2 substrate. The magnetization reversal of the continuous film is governed by domain-wall motion, while the magnetization reversal of the nanodot arrays is dominated by the Stoner–Wohlfarth-like rotation. These results indicate that the fabricated structure can be considered as an isolated nanodot array.
Finite element computations of resonant modes for small magnetic particles
Authors: Forestiere C. , d’Aquino M. , Miano G. , Serpico C.
Published: March 2009

The oscillations of a chain of ferromagnetic nanoparticles around a saturated spatially uniform equilibrium are analyzed by solving the linearized Landau–Lifshitz–Gilbert (LLG) equation. The linearized LLG equation is recast in the form of a generalized eigenvalue problem for suitable self-adjoint operators connected to the micromagnetic effective field, which accounts for exchange, magnetostatic, anisotropy, and Zeeman interactions. The generalized eigenvalue problem is solved numerically by the finite element method, which allows one to treat accurately complex geometries and preserves the structural properties of the continuum problem. The natural frequencies and the spatial distribution of the mode amplitudes are computed for chains composed of several nanoparticles (sphere and ellipsoid). The effects of the interaction between the nanoparticles and the limit of validity of the point dipole approximation are discussed.
Nonlinear interaction of dispersive Alfvén waves and magnetosonic waves in space plasma
Authors: Sharma R. P. , Kumar Sanjay , Singh H. D.
Published: March 2009

This paper presents the model equations governing the nonlinear interaction between dispersive Alfvén wave (DAW) and magnetosonic wave in the low-β plasmas (β⪡me/mi; known as inertial Alfvén waves) applicable to solar corona and intermediate-β plasmas (me/mi⪡β⪡1; known as kinetic Alfvén waves) applicable to solar wind in Earth’s magnetosphere. When the ponderomotive nonlinearities are incorporated in the DAW dynamics, the model equations of DAW and magnetosonic wave turn out to be a modified Zakharov system of equations. Numerical solution of the problem has been obtained when the incident pump kinetic Alfvén wave/inertial Alfvén wave is having a small perturbation.
Size-dependent solvation of p-H2 in H4e clusters: A quantum Monte Carlo analysis
Authors: Coccia E. , Bodo E. , Gianturco F. A.
Published: March 2009

Variable-size H4eN clusters doped with a single p-H2 molecule are studied here using variational and diffusion Monte Carlo calculations that show the highly quantum nature of the dopant and the solvent. Energetic and structural features extracted from our analysis reveal that the p-H2 molecule behaves as a gentle perturber: The He droplets remain essentially liquidlike, with no evident structural change with respect to the pure ones. The p-H2 dopant represents a kind of “competitor” for helium in the smaller droplets because it can replace the solvent adatoms; it also remains immersed in the cluster as N increases although located off-center within the droplet, while, finally, getting fully solvated in the larger droplets. The calculations are carried out up to N=100 as the largest number of solvent H4e atoms and clearly show no evidence of either shell structuring or of “magic” numbers in the size of the smaller droplets.
Structural, optical, and magnetic properties of Cu-implanted GaN films
Authors: Yang X. L. , Chen Z. T. , Wang C. D. , Zhang Y. , Pei X. D. , Yang Z. J. , Zhang G. Y. , Ding Z. B. , Wang K. , Yao S. D.
Published: March 2009

The structural, optical, and magnetic properties of Cu-implanted GaN films have been investigated. No secondary phase was found within the resolution limit of the instrument but the lattice defects such as vacancies were present in the film. Room temperature ferromagnetism was observed with saturation magnetization of 0.3μB/Cu atom. The field-cooled magnetization curves can be well fitted by a Curie-Weiss model and a standard three-dimensional spin-wave model in the low and high temperature ranges, respectively. Our findings indicate that the vacancylike defects should be considered in understanding the observed magnetic properties of the Cu-implanted GaN films.
A modified ansatz for explicitly correlated coupled-cluster wave functions that is suitable for response theory
Authors: Köhn Andreas
Published: March 2009

A modified ansatz for explicitly correlated coupled-cluster wave functions with a single correlation factor is set forward. It is based on the fixed amplitude ansatz of Ten-no [Chem. Phys. Lett. 398, 56 (2004)] to which an extra term is added that allows for the explicitly correlated description of singly excited configurations. The new approach has been implemented for coupled-cluster singles and doubles with the aid of automated techniques. Numerical results are presented for vertical excitation energies, and ground and excited state equilibrium distances and harmonic frequencies of diatomics. The new approach is shown to provide a nearly unbiased description of ground and predominantly singly exited states, and the improvements seen for explicitly correlated treatments of ground states, as compared to conventional orbital expansions, carry over to excited states. In addition, a correction for contributions from one-electron terms—which are not improved by the correlation factor—is suggested, again with focus on applicability to a response formalism.
Dynamic resistive crossbar memory based on conjugated polymer composite
Authors: Zhao Jun Hui , Thomson Douglas J. , Pillai Rajesh G. , Freund Michael S.
Published: March 2009

A semiconducting polypyrrole composite was designed to exhibit electric field dependent charge carrier distributions. Junctions were grown electrochemically on gold crossbars. Application of fields results in the drift of mobile cations, creating regions with higher conductivity and increased current. The field induced carrier redistribution results in field- and time-dependent current with good junction-to-junction repeatability. The electrical transport dominated by space charge limited current will have better scaling behavior than surface dominated and Ohmic devices as the dimensions are reduced to the nanometer scale.
Ballistic and snowplow regimes in J×B plasma acceleration
Authors: Thoma C. , Welch D. R. , Hughes T. P.
Published: March 2009

The J×B acceleration of a one-dimensional uniform plasma slab is analyzed using fully electromagnetic particle-in-cell simulations. Two different regimes of ion dynamics are observed. At relatively high magnetic field values, the ions are accelerated nearly ballistically in a thin sheath at the plasma-vacuum interface and then form a beam which propagates through the downstream bulk plasma. This behavior can be explained by a simple collisionless thin-sheath model. At lower field values the sheath becomes thicker and the ions are collisional at the interface. This leads to “snowplowing” of ion density at the interface. From the electron transport equations for a simple magnetized plasma we can estimate the temperature and effective collisionality in the sheath as a function of magnetic field strength. From this theory we can qualitatively explain the existence of the two regimes. In the simulations the plasma sheath thickness is found to scale somewhat more weakly with magnetic field strength than is predicted by the simple transport theory. We propose that a high Mach number plasma slab may be obtained by the combination of a short accelerator and a strong magnetic field in the collisionless regime.
Preparation and characterization of planar deuterium cryotargets
Authors: Lei Haile , Li Jun , Tang Yongjian , Liu Yuanqiong
Published: March 2009

Using a planar-cryotarget system with the cooling power provided by a Gifford–McMahon cryocooler, the deuterium vapor is condensed to form liquid in a cylinder target cell. The liquefaction processes of deuterium are examined by the Mach–Zehnder interference and infrared spectra. The infrared-absorption spectra of deuterium show a strong absorption peak around 3040 nm at 19 K. The thickness distribution of the condensed deuterium in the target cell is determined from Mach–Zehnder interference images by developing a new mathematical treatment method in combination with the digital-image processing technique.
Intra- and intermolecular electrostatic interactions and their significance for the structure, acidity, and tautomerization behavior of trinitromethane
Authors: Murray Jane S. , Lane Pat , Göbel Michael , Klapötke Thomas M. , Politzer Peter
Published: March 2009

We have addressed several interesting issues related to trinitromethane: the propellerlike arrangement of its nitro groups, its lower-than-predicted (although still high) acidity, its aci tautomerization, and the absence of expected very short C–H•••O intermolecular bridges in the crystal. A combination of crystallographic and computed data was used in our analysis. The structural features mentioned and the anomalous acidity can be attributed to intra- and/or intermolecular electrostatic interactions. Decomposition via C–NO2 bond scission may occur before aci tautomerization can take place.
Time dependent dc resistance degradation in lead-based perovskites: 0.7 Pb(Mg1/3Nb2/3)O3−0.3 PbTiO3
Authors: Zhao S. , Zhang S. J. , Liu W. , Donnelly N. J. , Xu Z. , Randall C. A.
Published: March 2009

Highly accelerated lifetime tests (HALTs), thermally stimulated depolarization current (TSDC), and impedance spectroscopy (IS) measurements were performed on 0.7 Pb(Mg1/3Nb2/3)O3−0.3 PbTiO3 (PMN-PT) single crystal to investigate time dependent dc resistance degradation under a dc bias. A low activation energy of 0.61±0.04 eV which controls the degradation process in PMN-PT single crystal is determined from the characteristic degradation time tC in HALT. Meanwhile, in a complementary TSDC investigation, a broad depolarization peak with an activation energy of 0.6±0.03 eV is observed in virgin PMN-PT single crystal having the characteristics of ionic space charge. Finally, impedance spectra of degraded PMN-PT single crystal exhibited three relaxations in contrast to two relaxations in virgin PMN-PT single crystal. In terms of equivalent circuit, an element combination R-ZCPE corresponding to ionic conduction is common to both virgin and degraded single crystals, and an activation energy about 0.64 eV, attributed to the ionic transport, is also obtained. This value is low compared to similar studies on alkaline-earth titanate perovskites, such as Fe-doped SrTiO3, however, here we suggest the activation energy about 0.6 eV from three independent measurements is attributed to the migration of oxygen vacancies in this particular lead-based single crystal, and besides this apparent ionic conduction, band electronic conduction is also discussed in both virgin and degraded single crystals in this paper.
The disparate impact of the ion temperature gradient and the density gradient on edge transport and the low-high transition in tokamaks
Authors: Kleva Robert G. , Guzdar Parvez N.
Published: March 2009

Steepening of the ion temperature gradient in nonlinear fluid simulations of the edge region of a tokamak plasma causes a rapid degradation in confinement. As the density gradient steepens, there is a continuous improvement in confinement analogous to the low (L) to high (H) transition observed in tokamaks. In contrast, as the ion temperature gradient steepens, there is a rapid increase in the particle and energy fluxes and no L-H transition. For a given pressure gradient, confinement always improves when more of the pressure gradient arises from the density gradient, and less of the pressure gradient arises from the ion temperature gradient.
Portable UV-visible spectrometer for measuring absorbance and dichroism of Langmuir monolayers at air-water interfaces.
Authors: Tronin Andrey , Strzalka Joseph , Krishnan Venkata , Kuzmenko Ivan , Fry H. Christopher , Therien Michael , Blasie J. Kent
Published: March 2009

An UV-visible spectrometer for measuring absorbance and dichroism of Langmuir monolayers under in situ conditions is described. The spectrometer utilizes a stand-alone multipass sensor, which is placed in a Langmuir trough and coupled with light source and spectrometer head via fiber optics. Implementation of the multipass scheme in the absorbance sensor makes it possible to obtain reliable quantitative spectroscopic data of the Langmuir monolayers with absorbance as low as 1 mOD. Such high sensitivity makes the developed sensor very useful for UV-visible spectral studies of a wide variety of chromophores. The new technique was applied to several model systems: fatty acid monolayers containing amphiphilic dyes DiI or BODIPY and also a monolayer of a synthetic amphiphilic porphyrin-binding peptide BBC16. Implementation of UV-visible absorbance spectroscopy measurements in situ together with x-ray scattering technique was used to confirm the bound state of the chromophore, and determine the exact position of the latter in the peptide matrix. Fiber optics design of the spectrometer provides portability and compatibility with other experimental techniques making it possible to study samples with a geometry unsuitable for conventional spectroscopic measurements and located in experimental environments with spatial limitations, such as synchrotron x-ray scattering stations.
The correlation between shear elastic modulus and glass transition temperature of bulk metallic glasses
Authors: Lu Zhibin , Li Jiangong , Shao Hang , Gleiter H. , Ni Xia
Published: March 2009

Based on Varshni equation, the shear elastic modulus at the glass transition temperature [G(Tg)] and the shear elastic modulus at 0 K [G(0)] were calculated from the elastic modulus measured at room temperature for various bulk metallic glasses (BMGs). The G(Tg)/G(0) ratios for various BMGs are almost the same and have a value around 0.85. This unique correlation implies that the glass transition occurs when the shear modulus of a BMG decreases to about 85% of G(0). This correlation between shear modulus and glass transition is of significance in understanding the glass transition of BMGs.
Hybrid waveguides for optically pumped amplifiers
Authors: Saini S. , Hong C.-Y. , Bernardis S. , Pfaff N. , Kimerling L. C. , Michel J.
Published: March 2009

A hybrid waveguide based on simultaneous propagation of photonic crystal (PC) and total internal reflection confined optical modes is introduced for a scheme to uniformly pump waveguide optical amplifiers (WOAs). Planar one-dimensional PC structures were deposited by plasma enhanced chemical vapor deposition and characterized by reflectivity as a function of angle, confirming the existence of PC defect states. Two design trade-offs, angular acceptance and critical coupling, are modeled to demonstrate optimization of optically pumped gain within the PC defect state. The advantage of uniform pumping on the WOA gain profile is briefly discussed.
Edge elastic properties of defect-free single-layer graphene sheets
Authors: Reddy C. D. , Ramasubramaniam A. , Shenoy V. B. , Zhang Yong-Wei
Published: March 2009

An energetic model is proposed to describe the edge elastic properties of defect-free single-layer graphene sheets. Simulations with the adaptive intermolecular reactive empirical bond order potential are used to extract the edge stress and edge moduli for different edges structures, namely, zigzag and armchair edges, zigzag and armchair edges terminated with hydrogen, and reconstructed zigzag and armchair edges. It is found that the properties of graphene are sensitively dependent on the edge structures; armchair and zigzag edges with and without hydrogen termination are in compression, while reconstructed edges are in tension.
Nanostructural origin of the spin and orbital contribution to the magnetic moment in Fe3−xO4 magnetite nanoparticles
Authors: Pérez N. , Bartolomé F. , García L. M. , Bartolomé J. , Morales M. P. , Serna C. J. , Labarta A. , Batlle X.
Published: March 2009

5 nm Fe3−xO4 nanoparticles were synthesized either by high-temperature decomposition in organic phase or in low-temperature aqueous conditions. In the first case oleic acid was covalently bonded to the nanoparticles; in the second case polyvinyl alcohol (PVA) yielded a protective coating without chemical bond. Magnetization measurements and x-ray magnetic circular dichroism showed a saturation magnetization close to bulk magnetite and an orbital moment effectively quenched in covalently bonded nanoparticles. PVA-coated nanoparticles showed a reduced value of the magnetization and ∼3 fold increase in the orbital moment. High resolution electron microscopy suggested that this was related to the nanostructure of the samples.
Stability, electronic, and magnetic behaviors of Cu adsorbed graphene: A first-principles study
Authors: Wu M. , Liu En-Zuo , Ge M. Y. , Jiang J. Z.
Published: March 2009

Stable configurations, electronic structures, and magnetic behaviors for Cu single atom and dimer adsorption on graphene have been investigated by first-principles calculations, using both gradient generalized approximation (GGA) and GGA+U methods. It is found that Cu single atom, sitting above a carbon atom, is the most stable configuration, while the most stable configuration for Cu dimer is perpendicular to the graphene plane above the bridge site. In both calculations, magnetic moments were detected in Cu single-atom-adsorbed graphene, which is mainly caused by the unsaturated s-electrons of the Cu atom. No magnetic moment was observed in Cu dimer-adsorbed graphene in both cases, but a band gap was observed in the GGA+U calculation, while a metallic system was observed in the GGA calculation. This demonstrates that the electronic structure of graphene can be modified via Cu adsorption. The Cu dimer, sitting parallel to the graphene plane above the C atoms, offers the possibility for the formation of Cu atom chain or wire on graphene, which might have potential nanoelectronic applications.
Dynamic changes in paternal X-chromosome activity during imprinted X-chromosome inactivation in mice
Authors: Patrat Catherine , Okamoto Ikuhiro , Diabangouaya Patricia , Vialon Vivian , Le Baccon Patricia , Chow Jennifer , Heard Edith
Published: March 2009

In mammals, X-chromosome dosage compensation is achieved by inactivating one of the two X chromosomes in females. In mice, X inactivation is initially imprinted, with inactivation of the paternal X (Xp) chromosome occurring during preimplantation development. One theory is that the Xp is preinactivated in female embryos, because of its previous silence during meiosis in the male germ line. The extent to which the Xp is active after fertilization and the exact time of onset of X-linked gene silencing have been the subject of debate. We performed a systematic, single-cell transcriptional analysis to examine the activity of the Xp chromosome for a panel of X-linked genes throughout early preimplantation development in the mouse. Rather than being preinactivated, we found the Xp to be fully active at the time of zygotic gene activation, with silencing beginning from the 4-cell stage onward. X-inactivation patterns were, however, surprisingly diverse between genes. Some loci showed early onset (4–8-cell stage) of X inactivation, and some showed extremely late onset (postblastocyst stage), whereas others were never fully inactivated. Thus, we show that silencing of some X-chromosomal regions occurs outside of the usual time window and that escape from X inactivation can be highly lineage specific. These results reveal that imprinted X inactivation in mice is far less concerted than previously thought and highlight the epigenetic diversity underlying the dosage compensation process during early mammalian development.
Identification of IL-17-producing FOXP3+regulatory T cells in humans
Authors: Voo Kui Shin , Wang Yui-Hsi , Santori Fabio R. , Boggiano Cesar , Wang Yi-Hong , Arima Kazuhiko , Bover Laura , Hanabuchi Shino , Khalili Jahan , Marinova Ekaterina , Zheng Biao , Littman Dan R. , Liu Yong-Jun
Published: March 2009

IL-17–producing CD4+T helper (Th17) cells have recently been defined as a unique subset of proinflammatory helper cells whose development depends on signaling initiated by IL-6 and TGF-β, autocrine activity of IL-21, activation of STAT3, and induction of the orphan nuclear receptor RORγt. The maintenance, expansion, and further differentiation of the committed Th17 cells depend on IL-1β and IL-23. IL-17 was originally found produced by circulating human CD45RO+memory T cells. A recent study found that human Th17 memory cells selectively express high levels of CCR6. In this study, we report that human peripheral blood and lymphoid tissue contain a significant number of CD4+FOXP3+T cells that express CCR6 and have the capacity to produce IL-17 upon activation. These cells coexpress FOXP3 and RORγt transcription factors. The CD4+FOXP3+CCR6+IL-17–producing cells strongly inhibit the proliferation of CD4+responder T cells. CD4+CD25high-derived T-cell clones express FOXP3, RORγt, and IL-17 and maintain their suppressive function via a cell-cell contact mechanism. We further show that human CD4+FOXP3+CCR6−regulatory T (Treg) cells differentiate into IL-17 producer cells upon T-cell receptor stimulation in the presence of IL-1β, IL-2, IL-21, IL-23, and human serum. This, together with the finding that human thymus does not contain IL-17–producing Treg cells, suggests that the IL-17+FOXP3+Treg cells are generated in the periphery. IL-17–producing Treg cells may play critical roles in antimicrobial defense, while controlling autoimmunity and inflammation.
A P-type ATPase importer that discriminates between essential and toxic transition metals
Authors: Lewinson Oded , Lee Allen T. , Rees Douglas C.
Published: March 2009

Transition metals, although being essential cofactors in many physiological processes, are toxic at elevated concentrations. Among the membrane-embedded transport proteins that maintain appropriate intracellular levels of transition metals are ATP-driven pumps belonging to the P-type ATPase superfamily. These metal transporters may be differentiated according to their substrate specificities, where the majority of pumps can extrude either silver and copper or zinc, cadmium, and lead. In the present report, we have established the substrate specificities of nine previously uncharacterized prokaryotic transition-metal P-type ATPases. We find that all of the newly identified exporters indeed fall into one of the two above-mentioned categories. In addition to these exporters, one importer,
Pseudomonas aeruginosa
Q9I147, was also identified. This protein, designated HmtA (heavy metal transporter A), exhibited a different substrate recognition profile from the exporters. In vivo metal susceptibility assays, intracellular metal measurements, and transport experiments all suggest that HmtA mediates the uptake of copper and zinc but not of silver, mercury, or cadmium. The substrate selectivity of this importer ensures the high-affinity uptake of essential metals, while avoiding intracellular contamination by their toxic counterparts.
Programmed assembly of 3-dimensional microtissues with defined cellular connectivity
Authors: Gartner Zev J. , Bertozzi Carolyn R.
Published: March 2009

Multicellular organs comprise differentiated cell types with discrete yet interdependent functions. The cells' spatial arrangements and interconnectivities, both critical elements of higher-order function, derive from complex developmental programs in vivo and are often difficult or impossible to emulate in vitro. Here, we report the bottom-up synthesis of microtissues composed of multiple cell types with programmed connectivity. We functionalized cells with short oligonucleotides to impart specific adhesive properties. Hybridization of complementary DNA sequences enabled the assembly of multicellular structures with defined cell–cell contacts. We demonstrated that the kinetic parameters of the assembly process depend on DNA sequence complexity, density, and total cell concentration. Thus, cell assembly can be highly controlled, enabling the design of microtissues with defined cell composition and stoichiometry. We used this strategy to construct a paracrine signaling network in isolated 3-dimensional microtissues.
Identification of the phosphorylation sites on the E3 ubiquitin ligase Pellino that are critical for activation by IRAK1 and IRAK4
Authors: Smith Hilary , Peggie Mark , Campbell David G. , Vandermoere Franck , Carrick Emma , Cohen Philip
Published: March 2009

The E3 ubiquitin ligase Pellino can be activated by phosphorylation in vitro, catalyzed by IL-1 receptor-associated kinase 1 (IRAK1) or IRAK4. Here, we show that phosphorylation enhances the E3 ligase activity of Pellino 1 similarly with any of several E2-conjugating enzymes (Ubc13-Uev1a, UbcH4, or UbcH5a/5b) and identify 7 amino acid residues in Pellino 1 whose phosphorylation is critical for activation. Five of these sites are clustered between residues 76 and 86 (Ser-76, Ser-78, Thr-80, Ser-82, and Thr-86) and decorate a region of antiparallel β-sheet, termed the “wing,” which is an appendage of the forkhead-associated domain that is thought to interact with IRAK1. The other 2 sites are located at Thr-288 and Ser-293, just N-terminal to the RING-like domain that carries the E3 ligase activity. Unusually, the full activation of Pellino 1 can be achieved by phosphorylating any one of several different sites (Ser-76, Thr-86, Thr-288, or Ser-293) or a combination of other sites (Ser-78, Thr-80, and Ser-82). These observations imply that dephosphorylation of multiple sites is required to inactivate Pellino 1, which could be a device for prolonging Pellino's E3 ubiquitin ligase activity in vivo.
Heterojunctions between metals and carbon nanotubes as ultimate nanocontacts
Authors: Rodríguez-Manzo Julio A. , Banhart Florian , Terrones Mauricio , Terrones Humberto , Grobert Nicole , Ajayan Pulickel M. , Sumpter Bobby G. , Meunier Vincent , Wang Mingsheng , Bando Yoshio , Golberg Dmitri
Published: March 2009

We report the controlled formation and characterization of heterojunctions between carbon nanotubes and different metal nanocrystals (Fe, Co, Ni, and FeCo). The heterojunctions are formed from metal-filled multiwall carbon nanotubes (MWNTs) via intense electron beam irradiation at temperatures in the range of 450–700 °C and observed in situ in a transmission electron microscope. Under irradiation, the segregation of metal and carbon atoms occurs, leading to the formation of heterojunctions between metal and graphite. Metallic conductivity of the metal–nanotube junctions was found by using in situ transport measurements in an electron microscope. Density functional calculations show that these structures are mechanically strong, the bonding at the interface is covalent, and the electronic states at and around the Fermi level are delocalized across the entire system. These properties are essential for the application of such heterojunctions as contacts in electronic devices and vital for the fabrication of robust nanotube–metal composite materials.
CX3CR1+ CD115+ CD135+ common macrophage/DC precursors and the role of CX3CR1 in their response to inflammation
Authors: Auffray Cedric , Fogg Darin K. , Narni-Mancinelli Emilie , Senechal Brigitte , Trouillet Celine , Saederup Noah , Leemput Julia , Bigot Karine , Campisi Laura , Abitbol Marc , Molina Thierry , Charo Israel , Hume David A. , Cumano Ana , Lauvau Gregoire , Geissmann Frederic
Published: March 2009

CX3CR1 expression is associated with the commitment of CSF-1R+ myeloid precursors to the macrophage/dendritic cell (DC) lineage. However, the relationship of the CSF-1R+ CX3CR1+ macrophage/DC precursor (MDP) with other DC precursors and the role of CX3CR1 in macrophage and DC development remain unclear. We show that MDPs give rise to conventional DCs (cDCs), plasmacytoid DCs (PDCs), and monocytes, including Gr1+ inflammatory monocytes that differentiate into TipDCs during infection. CX3CR1 deficiency selectively impairs the recruitment of blood Gr1+ monocytes in the spleen after transfer and during acute Listeria monocytogenes infection but does not affect the development of monocytes, cDCs, and PDCs.
Circulating and gut-resident human Th17 cells express CD161 and promote intestinal inflammation
Authors: Kleinschek Melanie A. , Boniface Katia , Sadekova Svetlana , Grein Jeff , Murphy Erin E. , Turner Scott P. , Raskin Lisa , Desai Bela , Faubion William A. , de Waal Malefyt Rene , Pierce Robert H. , McClanahan Terrill , Kastelein Robert A.
Published: March 2009

The C-type lectin-like receptor CD161, which has recently been described to promote T cell expansion, is expressed on a discrete subset of human CD4 T cells. The function of such cells, however, has remained elusive. We now demonstrate that CD161+ CD4 T cells comprise a circulating and gut-resident T helper 17 (Th17) cell population. During Crohn's disease (CD), these CD161+ cells display an activated Th17 phenotype, as indicated by increased expression of interleukin (IL)-17, IL-22, and IL-23 receptor. CD161+ CD4 T cells from CD patients readily produce IL-17 and interferon γ upon stimulation with IL-23, whereas, in healthy subjects, priming by additional inflammatory stimuli such as IL-1β was required to enable IL-23–induced cytokine release. Circulating CD161+ Th17 cells are imprinted for gut homing, as indicated by high levels of CC chemokine receptor 6 and integrin β7 expression. Supporting their colitogenic phenotype, CD161+ Th17 cells were found in increased numbers in the inflammatory infiltrate of CD lesions and induced expression of inflammatory mediators by intestinal cells. Our data identify CD161+ CD4 T cells as a resting Th17 pool that can be activated by IL-23 and mediate destructive tissue inflammation.
Critical role of phospholipase Cγ2 in integrin and Fc receptor-mediated neutrophil functions and the effector phase of autoimmune arthritis
Authors: Jakus Zoltán , Simon Edina , Frommhold David , Sperandio Markus , Mócsai Attila
Published: March 2009

β2 integrins and Fcγ receptors are critically involved in neutrophil activation at the site of inflammation. Both receptor types trigger a receptor-proximal tyrosine phosphorylation cascade through Src family kinases and Syk, but further downstream signaling events are poorly understood. We show that phospholipase C (PLC) γ2 is phosphorylated downstream of Src family kinases and Syk during integrin or Fc receptor-mediated activation of neutrophils. PLCγ2−/− neutrophils are completely defective in β2 integrin or Fcγ receptor-mediated functional responses such as respiratory burst, degranulation, or cell spreading in vitro and show reduced adhesion/spreading in inflamed capillary venules in vivo. However, PLCγ2−/− neutrophils respond normally to various other agonists, including chemokines, bacterial formyl peptides, Toll-like receptor ligands, or proinflammatory cytokines, and migrate normally both in vitro and in vivo. To confirm the in vivo relevance of these observations, the effect of the PLCγ2−/− mutation was tested in the K/B×N serum transfer arthritis model, which is known to require β2 integrins, Fcγ receptors, and neutrophils. PLCγ2 deficiency completely protected mice from clinical signs and histological features of arthritis as well as from arthritis-induced loss of articular function. These results identify PLCγ2 as a critical player of integrin and Fc receptor-mediated neutrophil functions and the neutrophil-mediated effector phase of autoimmune arthritis.
MULTIPOLE FORMULAE FOR GRAVITATIONAL LENSING SHEAR AND FLEXION
Authors: Bernstein Gary M. , Nakajima Reiko
Published: March 2009

The gravitational lensing equations for convergence, potential, shear, and flexion are simple in polar coordinates and separate under a multipole expansion once the shear and flexion spinors are rotated into a “tangential” basis. We use this to investigate whether the useful monopole aperture–mass shear formulae generalize to all multipoles and to flexions. We re-derive the result of Schneider and Bartelmann that the shear multipole m at radius R is completely determined by the mass multipole at R, plus specific moments Q
(m)
in and Q
(m)
out of the mass multipoles internal and external, respectively, to R. The m ⩾ 0 multipoles are independent of Q
out. But in contrast to the monopole, the m < 0 multipoles are independent of Q
in. These internal and external mass moments can be determined by shear (and/or flexion) data on the complementary portion of the plane, which has practical implications for lens modeling. We find that the ease of E/B separation in the monopole aperture moments does not generalize to m ≠ 0: the internal monopole moment is the only nonlocal E/B discriminant available from lensing observations. We have also not found practical local
E/B discriminants beyond the monopole, though they could exist. We show also that the use of weak-lensing data to constrain a constant shear term near a strong-lensing system is impractical without strong prior constraints on the neighboring mass distribution.
Conservation and variation of the parapoxvirus GM-CSF-inhibitory factor (GIF) proteins
Authors: Deane D. , Ueda N. , Wise L. M. , Wood A. R. , Percival A. , Jepson C. , Inglis N. F. , Fleming S. B. , Mercer A. A. , McInnes C. J.
Published: March 2009

The GIF protein of orf virus (ORFV) binds and inhibits the ovine cytokines granulocyte–macrophage colony-stimulating factor (GM-CSF) and interleukin-2 (IL-2). An equivalent protein has so far not been found in any of the other poxvirus genera and we therefore investigated whether it was conserved in the parapoxviruses. The corresponding genes from both the bovine-specific pseudocowpox virus (PCPV) and bovine papular stomatitis virus (BPSV) were cloned and sequenced. The predicted amino acid sequences of the PCPV and BPSV proteins shared 88 and 37 % identity, respectively, with the ORFV protein. Both retained the six cysteine residues and the WSXWS-like motif that are required for biological activity of the ORFV protein. However, an analysis of the biological activity of the two recombinant proteins revealed that, whilst the PCPV GIF protein bound to both ovine and bovine GM-CSF and IL-2 with very similar binding affinities to the ORFV GIF protein, no GM-CSF- or IL-2-binding activity was found for the BPSV protein.