bluuebunny/crossref_metadata_2025 huggingface dataset:
Online simulations of global aerosol distributions in the NASA GEOS‐4 model and comparisons to satellite and ground‐based aerosol optical depth
Authors: Colarco Peter , da Silva Arlindo , Chin Mian , Diehl Thomas
Published: August 2010

We have implemented a module for tropospheric aerosols (GOCART) online in the NASA Goddard Earth Observing System version 4 model and simulated global aerosol distributions for the period 2000–2006. The new online system offers several advantages over the previous offline version, providing a platform for aerosol data assimilation, aerosol‐chemistry‐climate interaction studies, and short‐range chemical weather forecasting and climate prediction. We introduce as well a methodology for sampling model output consistently with satellite aerosol optical thickness (AOT) retrievals to facilitate model‐satellite comparison. Our results are similar to the offline GOCART model and to the models participating in the AeroCom intercomparison. The simulated AOT has similar seasonal and regional variability and magnitude to Aerosol Robotic Network (AERONET), Moderate Resolution Imaging Spectroradiometer, and Multiangle Imaging Spectroradiometer observations. The model AOT and Angstrom parameter are consistently low relative to AERONET in biomass‐burning‐dominated regions, where emissions appear to be underestimated, consistent with the results of the offline GOCART model. In contrast, the model AOT is biased high in sulfate‐dominated regions of North America and Europe. Our model‐satellite comparison methodology shows that diurnal variability in aerosol loading is unimportant compared to sampling the model where the satellite has cloud‐free observations, particularly in sulfate‐dominated regions. Simulated sea salt burden and optical thickness are high by a factor of 2–3 relative to other models, and agreement between model and satellite over‐ocean AOT is improved by reducing the model sea salt burden by a factor of 2. The best agreement in both AOT magnitude and variability occurs immediately downwind of the Saharan dust plume.
Variations of net ecosystem CO2 exchange in a tidal inundated wetland: Coupling MODIS and tower‐based fluxes
Authors: Yan Yan‐Er , Guo Hai‐Qiang , Gao Yu , Zhao Bin , Chen Ji‐Quan , Li Bo , Chen Jia‐Kuan
Published: August 2010

Tidal activity is a major factor determining the distribution of plant species and ecosystem functions, including carbon fluxes. To explore the spatial variations of net ecosystem CO2 exchange (NEE) and related regulatory mechanisms along the tidal inundation gradient (i.e., middle or low tidal flat), an NEE estimation model using piecewise regression analysis was developed by coupling the Moderate Resolution Imaging Spectroradiometer (MODIS)‐ and tower‐based measurements. The results showed that our model achieved an adequate NEE estimation (slope = 0.70, R2 = 0.78). Then the model was applied to estimate NEE variation along a transect with a tidal inundation gradient. The average NEE was −1.75 g C m−2 d−1, varying from −2.02 g C m−2 d−1 to −1.42 g C m−2 d−1 from island‐ to oceanside. Generally, our empirical model captured the spatiotemporal patterns of NEE and the variation of the regulatory factors along the gradient. The sensitivity analysis of various regulatory variables showed that the variations of NEE near the islandside were primarily caused by seasonal shift and annual cycle of vegetation, whereas at the oceanside, NEE was more influenced by tidal activity with no clear phenological influence. In the middle area, NEE seemed to be subjected to both phenological changes of vegetation and tidal activity. In conclusion, this study illustrates that the estimates derived from MODIS‐ and tower‐based flux data are reliable for quantifying the spatiotemporal variations of NEE and reflecting the effect of tidal activity on NEE.
Observation of surface seismic activity changes of an Alpine glacier during a glacier‐dammed lake outburst
Authors: Roux P.‐F. , Walter F. , Riesen P. , Sugiyama S. , Funk M.
Published: August 2010

During the 2004 outburst flood of Gornersee, Switzerland, we observed surface microseismic activity (so‐called icequakes) near the glacier‐dammed lake on Gornergletscher. Using surface waves, we located near‐surface tensile fracturing events by inverting time delays using a quasi‐Newton scheme. We located 8520 near‐surface events with uncertainties of less than 10 m. Seismic activity increased during the lake drainage, and the icequake epicenters migrated downglacier. Furthermore, we identified events whose fault plane orientations are nearly perpendicular to the local pattern of surface crevassing. These observations can be explained by the rotation of principal strains at the glacier surface deduced from local ice flow measurement which occurred during the flotation of the ice dam at the onset of the lake drainage. In general, we suggest that our technique is a useful tool to locate large data sets of microseismic events and can be used to monitor the temporal evolution of fracture processes and their dependence on glacier flow and glacier hydrology.
Probability distributions of bed load transport rates: A new derivation and comparison with field data
Authors: Turowski Jens M.
Published: August 2010

It has been known for a long time that sediment transport rates can vary strongly even if the ambient hydraulic conditions remain steady. In this article, a new approach is described to derive probability distributions of bed load transport rates, starting from the waiting time between the arrivals of individual sediment particles. The formalism should be valid when transport is not dominated by bed form motion. Without any assumptions about the distribution of interarrival times, the approach yields the Birnbaum‐Saunders distribution, a two‐parameter distribution previously used in lifetime modeling. Observed dependence of mean transport rates on the sampling time and multiscaling are predicted by the distribution. Assuming exponentially and Poisson‐distributed interarrival times, the same approach yields the Poisson and the gamma distributions. Using a high‐resolution bed load transport data set from the Pitzbach, Austria, the distribution functions are tested on field data. The gamma distribution best describes the data, with maximum deviations of ∼5%. However, the Birnbaum‐Saunders distribution may be more useful in certain applications, as it is a general approximation in the proposed formalism and no debated assumptions are necessary for its derivation.
Participatory development of a Bayesian network model for catchment‐based water resource management
Authors: Chan T. , Ross H. , Hoverman S. , Powell B.
Published: August 2010

A participatory approach was used to develop a Bayesian network model for assisting integration of water resource management in the Kongulai catchment in the Solomon Islands. This catchment provides 40–60% of the water for Honiara, the capital, and management is complex, with sparse data and many competing uses including drinking, domestic, agricultural, and industrial uses for both water and land in the catchment, as well as a range of threats from pollution, increasing population, changing land use, and variable hydrogeology. There are socioeconomic considerations including customary landownership and overlapping institutional responsibilities. A participatory process involving representative stakeholders of three main groups, the customary landowners, the government, and nongovernmental organizations, was central to analyzing the system and building trust in the model development process and model outcomes, and additionally facilitated relationship building between the different groups affecting, and affected by, the catchment. A conceptual model of the Kongulai system with respect to water was developed with all stakeholders. Further elicitation of quantitative aspects took place with a subset of water management professionals for development into a working Bayesian network model. Stakeholder representatives were then presented with the model, some analysis, and scenarios for discussion and feedback. The model provided a number of recommendations that support local management decision making, which were accepted by the wider stakeholder group. The process demonstrates the worth of a well‐designed participatory approach to enhance stakeholder contributions and confirms the appropriateness of Bayesian networks for use in developing country contexts where capacity and data may be scarce.
Hydrologic evaluation of Multisatellite Precipitation Analysis standard precipitation products in basins beyond its inclined latitude band: A case study in Laohahe basin, China
Authors: Yong Bin , Ren Li‐Liang , Hong Yang , Wang Jia‐Hu , Gourley Jonathan J. , Jiang Shan‐Hu , Chen Xi , Wang Wen
Published: August 2010

Two standard Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) products, 3B42RT and 3B42V6, were quantitatively evaluated in the Laohahe basin, China, located within the TMPA product latitude band (50°NS) but beyond the inclined TRMM satellite latitude band (36°NS). In general, direct comparison of TMPA rainfall estimates to collocated rain gauges from 2000 to 2005 show that the spatial and temporal rainfall characteristics over the region are well captured by the 3B42V6 estimates. Except for a few months with underestimation, the 3B42RT estimates show unrealistic overestimation nearly year round, which needs to be resolved in future upgrades to the real‐time estimation algorithm. Both model‐parameter error analysis and hydrologic application suggest that the three‐layer Variable Infiltration Capacity (VIC‐3L) model cannot tolerate the nonphysical overestimation behavior of 3B42RT through the hydrologic integration processes, and as such the 3B42RT data have almost no hydrologic utility, even at the monthly scale. In contrast, the 3B42V6 data can produce much better hydrologic predictions with reduced error propagation from input to streamflow at both the daily and monthly scales. This study also found the error structures of both RT and V6 have a significant geo‐topography‐dependent distribution pattern, closely associated with latitude and elevation bands, suggesting current limitations with TRMM‐era algorithms at high latitudes and high elevations in general. Looking into the future Global Precipitation Measurement (GPM) era, the Geostationary Infrared (GEO‐IR) estimates still have a long‐term role in filling the inevitable gaps in microwave coverage, as well as in enabling sub‐hourly estimates at typical 4‐km grid scales. Thus, this study affirms the call for a real‐time systematic bias removal in future upgrades to the IR‐based RT algorithm using a simple scaling factor. This correction is based on MW‐based monthly rainfall climatologies applied to the combined monthly satellite‐gauge research products.
Uncertainties of global warming metrics: CO2 and CH4
Authors: Reisinger Andy , Meinshausen Malte , Manning Martin , Bodeker Greg
Published: August 2010

We present a comprehensive evaluation of uncertainties in the Global Warming Potential (GWP) and Global Temperature Change Potential (GTP) of CH4, using a simple climate model calibrated to AOGCMs and coupled climate‐carbon cycle models assessed in the IPCC Fourth Assessment Report (AR4). In addition, we estimate uncertainties in these metrics probabilistically by using a method that does not rely on AOGCMs but instead builds on historical constraints and uncertainty estimates of current radiative forcings. While our mean and median GWPs and GTPs estimates are consistent with previous studies, our analysis suggests that uncertainty ranges for GWPs are almost twice as large as estimated in the AR4. Relative uncertainties for GTPs are larger than for GWPs, nearly twice as high for a time horizon of 100 years. Given this uncertainty, our results imply the possibility for substantial future adjustments in best‐estimate values of GWPs and in particular GTPs.
Global climate changes recorded in coastal wetland sediments: Empirical observations linked to theoretical predictions
Authors: Kolker Alexander S. , Kirwan Matthew L. , Goodbred Steven L. , Cochran J. Kirk
Published: August 2010

Whether coastal areas are experiencing, and responding to, an accelerated rate of global sea‐level rise (GSLR) is critically important for the ∼2 billion people living near Earth's oceans. Accretion rates from a suite of physiographically diverse coastal wetlands surrounding Long Island, NY accelerated during the 20th century at 2.3 ± 0.2 × 10−2 mm yr−2, which is comparable to reported rates of GSLR acceleration and global temperature changes. Wetlands varied in tidal range, salinity and geomorphic setting, and were located in embayments with limited human impacts in a region with limited and constant rates of subsidence. From geochronologies with temporal resolutions of 2–5 yr, we constructed new composite histories of sediment accretion and mineral deposition. Wetland dynamics are consistent with predictions from sedimentology and a numerical model of ecogeomorphic response, suggesting that these systems, and likely others worldwide, are responding to accelerated GSLR and related climatic changes.
Estimates of global ocean volume transports during 1960 through 2001
Authors: Wang Weiqiang , Köhl Armin , Stammer Detlef
Published: August 2010

An estimate of global time‐varying ocean volume transports is provided for the period 1960–2001 as it results from the German ECCO (GECCO) synthesis. Results confirm previously discussed mean‐state ocean circulation systems, encompassing an upper meridional cell in the Atlantic with sinking in the North Atlantic connected to a lower meridional cell with sinking around Antarctica in the Pacific and Atlantic. Decadal to interdecadal variability as well as long‐term trends of global ocean transport, analyzed over the course of the 42 years, appear as a reorganization of time‐mean circulation structures, including the layer transports in the Antarctic Circumpolar Current (ACC) and the circulation involving the Indo‐Pacific exchange.
Theory and observation of electromagnetic ion cyclotron triggered emissions in the magnetosphere
Authors: Omura Yoshiharu , Pickett Jolene , Grison Benjamin , Santolik Ondrej , Dandouras Iannis , Engebretson Mark , Décréau Pierrette M. E. , Masson Arnaud
Published: August 2010

We develop a nonlinear wave growth theory of electromagnetic ion cyclotron (EMIC) triggered emissions observed in the inner magnetosphere. We first derive the basic wave equations from Maxwell's equations and the momentum equations for the electrons and ions. We then obtain equations that describe the nonlinear dynamics of resonant protons interacting with an EMIC wave. The frequency sweep rate of the wave plays an important role in forming the resonant current that controls the wave growth. Assuming an optimum condition for the maximum growth rate as an absolute instability at the magnetic equator and a self‐sustaining growth condition for the wave propagating from the magnetic equator, we obtain a set of ordinary differential equations that describe the nonlinear evolution of a rising tone emission generated at the magnetic equator. Using the physical parameters inferred from the wave, particle, and magnetic field data measured by the Cluster spacecraft, we determine the dispersion relation for the EMIC waves. Integrating the differential equations numerically, we obtain a solution for the time variation of the amplitude and frequency of a rising tone emission at the equator. Assuming saturation of the wave amplitude, as is found in the observations, we find good agreement between the numerical solutions and the wave spectrum of the EMIC triggered emissions.
Role of different Escherichia coli hydrogenases in H+ efflux and F1Fo-ATPase activity during glycerol fermentation at different pH values
Authors: Blbulyan Syuzanna , Avagyan Arev , Poladyan Anna , Trchounian Armen
Published: August 2010

Escherichia coli is able to ferment glycerol and produce H2 by different Hyds (hydrogenases). Wild-type whole cells were shown to extrude H+ through the F1Fo-ATPase and by other means with a lower rate compared with that under glucose fermentation. At pH 7.5, H+ efflux was stimulated in fhlA mutant (with defective transcriptional activator of Hyd-3 or Hyd-4) and was lowered in hyaB or hybC mutants (with defective Hyd-1 or Hyd-2) and hyaB hybC double mutant; DCCD (dicyclohexylcarbodi-imide)-sensitive H+ efflux was observed. At pH 5.5, H+ efflux in wild-type was lower compared with that at pH 7.5; it was increased in fhlA mutant and absent in hyaB hybC mutant. Membrane vesicle ATPase activity was lower in wild-type glycerol-fermented cells at pH 7.5 compared with that in glucose-fermented cells; 100 mM K+ did not stimulate ATPase activity. The latter at pH 7.5, compared with that in wild–type, was lower in hyaB and less in hybC mutants, stimulated in the hyaB hybC mutant and suppressed in the fhlA mutant; DCCD inhibited ATPase activity. At pH 5.5, the ATPase activities of hyaB and hybC mutants had similar values and were higher compared with that in wild-type; ATPase activity was suppressed in hyaB hybC and fhlA mutants. The results indicate that during glycerol fermentation, H+ was expelled also via F1Fo. At pH 7.5 Hyd-1 and Hyd-2 but not FhlA or Hyd-4 might be related to F1Fo or have their own H+-translocating ability. At pH 5.5, both Hyd-1 and Hyd-2 more than F1Fo might be involved in H+ efflux.
On the structure and dynamics of sheared and rotating turbulence: Anisotropy properties and geometrical scale-dependent statistics
Authors: Jacobitz Frank G. , Schneider Kai , Bos Wouter J. T. , Farge Marie
Published: August 2010

This study is based on a series of nine direct numerical simulations of homogeneous turbulence, in which the rotation ratio f/S of Coriolis parameter to shear rate is varied. The presence of rotation stabilizes the flow, except for a narrow range of rotation ratios 0<f/S<1. The main mechanism for the flow’s destabilization is an increased turbulence production due to increased anisotropy. Reynolds stress and the dissipation rate anisotropy tensors have been evaluated and provide a reference for newly defined anisotropy measures. Wavelet-based directional energies capture the properties of velocity gradients. The intermittency of the flow in different directions is quantified with scale-dependent directional flatness. Scale-dependent helicity probability distribution functions allow one to statistically characterize the geometry of the motion at different scales. Small scales are found locally to be predominantly helical, while large scales are not since they tend to two-dimensionalization for cases with growing turbulent kinetic energy. Joint probability distribution functions show that the signs of velocity helicity and vorticity helicity are strongly correlated. This indicates that vorticity helicity tends to diminish velocity helicity.
Enhancement of white light emission from novel Ca3Y2Si3O12:Dy3+ phosphors with Ce3+ ion codoping
Authors: Bandi Vengala Rao , Nien Yung-Tang , Chen In-Gann
Published: August 2010

The luminescent properties of the Ce3+ or Dy3+ singly doped and Ce3+/Dy3+ codoped in Ca3Y2Si3O12 novel phosphors were investigated, which are prepared by a sol-gel method. Ce3+ doped phosphor showed a brighter and broader violet-blue color emission band with a maximum peak centered at 389 nm, which is attributed to the parity and spin allowed 5d–4f transition. Photoluminescence spectra reveals that the white color emission is originated from the mixtures of two characteristic emission bands of Dy3+ ion, viz., the 473 nm blue emission (F49/2-H615/2) and the 580 nm yellow emission (F49/2-H613/2). codoping of Ce3+ has enhanced the luminescence of Dy3+ quite significantly upon the UV excitation wavelength (242 nm) and the optimized codopant concentration of Ce3+ is found to be 3 mol %. The mechanism involved in the energy transfer between Ce3+ and Dy3+ has been elucidated by an energy level diagram. The structure and morphology of the prepared samples have been analyzed by x-ray diffraction and transmission electron microscope.
In situ growth of superconducting NdFeAs(O,F) thin films by molecular beam epitaxy
Authors: Kawaguchi T. , Uemura H. , Ohno T. , Tabuchi M. , Ujihara T. , Takenaka K. , Takeda Y. , Ikuta H.
Published: August 2010

Superconducting NdFeAs(O,F) thin films were grown on GaAs substrates by molecular beam epitaxy. Films grown with a sufficiently long growth time exhibited a clear superconducting transition with an onset temperature up to 48 K and zero resistance temperature up to 42 K without the need of an ex situ annealing process. Electron probe microanalysis and Hall coefficient measurements indicated that the superconducting films are doped with fluorine, and depth-profile analysis by Auger electron spectroscopy revealed the formation of a NdOF layer near the surface, which is probably connected with the fluorine doping.
A semiclassical correction for quantum mechanical energy levels
Authors: Kaledin Alexey L. , McCurdy C. William , Miller William H.
Published: August 2010

We propose a semiclassical method for correcting molecular energy levels obtained from a quantum mechanical variational calculation. A variational calculation gives the energy level (i.e., eigenvalue) as the expectation value of the molecular Hamiltonian ⟨ϕ|Ĥ|ϕ⟩, where |ϕ⟩ is the trial wave function. The true (i.e., exact) eigenvalue E can thus be expressed as this variational result plus a correction, i.e., E=⟨ϕ|Ĥ|ϕ⟩+ΔE, the correction being due to the lack of exactness of the trial wave function. A formally exact expression for ΔE is usually given (via Löwdin partitioning methodology) in terms of the Greens function of the Hamiltonian projected onto the orthogonal complement of |ϕ⟩. Formal treatment of this expression (using Brillouin–Wigner perturbation theory to infinite order) leads to an expression for ΔE that involves matrix elements of the Greens function for the unprojected, i.e., full molecular Hamiltonian, which can then be approximated semiclassically. (Specifically, the Greens function is expressed as the Fourier transform of the quantum mechanical time evolution operator, e−iĤt/ℏ, which in turn is approximated by using an initial value representation of semiclassical theory.) Calculations for several test problems (a one dimensional quartic potential, and vibrational energy levels of H2O and H2CO) clearly support our proposition that the error in the total eigenvalue E arises solely due to the semiclassical error in approximating ΔE, which is usually a small fraction of the total energy E itself.
Cross sections for rotational decoherence of perturbed nitrogen measured via decay of laser-induced alignment
Authors: Owschimikow N. , Königsmann F. , Maurer J. , Giese P. , Ott A. , Schmidt B. , Schwentner N.
Published: August 2010

We quantitatively determine cross sections for rotational decoherence from the decay of nonadiabatic laser-induced alignment in nitrogen and nitrogen-foreign gas mixtures in a temperature range between 80 K and room temperature. The cross section for rotational decoherence in pure nitrogen decreases from 102 Å2 at 80 K to 48 Å2 at 295 K, leading to long-lived coherences even at high temperatures. Comparison with the broadening of the transition lines of the Raman Q-branch reported in the literature shows that the decay of rotational coherence proceeds at the same rate as rotational depopulation. This is verified also for mixtures of nitrogen with hydrogen, helium, argon, and krypton. We discuss limits posed by a possible J-dependence of the cross sections and strategies for state resolved determination from the time-dependent alignment signal.
Flame-made niobium doped zinc oxide nanoparticles in bulk heterojunction solar cells
Authors: Kruefu Viruntachar , Peterson Eric , Khantha Chanitpa , Siriwong Chawarat , Phanichphant Sukon , Carroll David L.
Published: August 2010

We report fabrication and measurement of bulk heterojunction solar cells utilizing a poly(3-hexylthiophene) (P3HT), phenyl-C61-butyric acid methyl ester (PCBM) composite loaded with different concentrations of niobium doped zinc oxide (Nb/ZnO) nanoparticles produced by flame spray pyrolysis. Nanoparticles with different niobium concentrations were compared, along with devices without Nb/ZnO nanoparticles and with undoped ZnO nanoparticles. It was found that niobium doping leads to a slight increase in open circuit voltage and an increase in short circuit current that scales with niobium concentration. Additional comparison was made between the nanoparticles with 3% niobium by weight to unloaded devices. These also showed a similar open circuit voltage increase and an increase in current that scales with Nb/ZnO nanoparticle concentration to 30% by volume and drops off at 33% Nb/ZnO by volume. Possible mechanisms for these improvements are discussed.
Local structure and site substitution in amorphous and quasicrystalline Zr–Ti–Ni–(Cu) alloys
Authors: Mechler S. , Schumacher G. , Koteski V. , Riesemeier H. , Schäfers F. , Mahnke H.-E.
Published: August 2010

Local structures of amorphous and quasicrystalline phases in Zr–Ti–Ni and Zr–Ti–Ni–Cu alloys have been studied by means of x-ray absorption spectroscopy. The amorphous phases show a high degree of icosahedral short-range order. In all investigated systems local order around Cu and Ni atoms was found to be nearly identical pointing to site substitution of Ni by Cu as the reason for an improved glass forming ability when Ni is partly substituted by Cu. The results strengthen an icosahedral cluster based approach for the structure of metallic glasses and indicate the importance of the medium-range order on glass formation.
Imaging of microwave fields using ultracold atoms
Authors: Böhi Pascal , Riedel Max F. , Hänsch Theodor W. , Treutlein Philipp
Published: August 2010

We report a technique that uses clouds of ultracold atoms as sensitive, tunable, and noninvasive probes for microwave field imaging with micrometer spatial resolution. The microwave magnetic field components drive Rabi oscillations on atomic hyperfine transitions whose frequency can be tuned with a static magnetic field. Readout is accomplished using state-selective absorption imaging. Quantitative data extraction is simple and it is possible to reconstruct the distribution of microwave magnetic field amplitudes and phases. While we demonstrate two-dimensional imaging, an extension to three-dimensional imaging is straightforward. We use the method to determine the microwave near-field distribution around a coplanar waveguide integrated on an atom chip.
Dielectric barrier discharge control of a turbulent boundary layer in a supersonic flow
Authors: Im S. , Do H. , Cappelli M. A.
Published: August 2010

We demonstrate effective manipulation of a turbulent boundary layer at Mach 4.7 conditions using a surface dielectric barrier discharge (DBD) actuator. The freestream conditions of low static pressure (1 kPa) and temperature (60 K) are conducive to the visualization of flow features using Rayleigh scattering from condensed CO2 particles. The boundary layer thinning is observed when spanwise momentum is induced by the low power (6.8 W), low frequency (28 kHz) single actuator pair oriented parallel to the freestream flow.
Observation of the forbidden doublet optical phonon in Raman spectra of strained Si for stress analysis
Authors: Poborchii Vladimir , Tada Tetsuya , Kanayama Toshihiko
Published: August 2010

Using high numerical aperture lenses, we detected doublet optical phonon, forbidden by selection rules, in Raman spectra of Si strained in the (001) plane (bulk Si as well as strained Si device structure grown on SiGe). This allowed us to quantitatively determine stress and its distribution in strained Si with the ∼10% accuracy, assuming symmetric biaxial stress. At the same time, we demonstrate some deviations of the real stress from the assumed model. For better accuracy, one has to consider these deviations as well as a possibility of improvement of available Si phonon deformation potential values.
Magnetization reversal and anisotropic magnetoresistance behavior in bicomponent antidot nanostructures
Authors: Tripathy D. , Vavassori P. , Porro J. M. , Adeyeye A. O. , Singh N.
Published: August 2010

We report on the magnetic properties and anisotropic magnetoresistance behavior of engineered bicomponent array of “holes” with alternating diameters embedded in a continuous permalloy film. We observed that the magnetization reversal is significantly altered when compared to a homogeneous array of antidots, and exhibits strong dependence on the permalloy thickness. Our results demonstrate that the use of two antidot sublattices greatly enhances the parameters available for engineering the behavior of antidot nanostructures.
Symmetry and electronic states of Mn2+ in ZnS nanowires with mixed hexagonal and cubic stacking
Authors: Chen Li , Kirilenko Demid , Stesmans Andre , Nguyen Xuan Sang , Binnemans Koen , Goderis Bart , Vanacken Johan , Lebedev Oleg , Van Tendeloo Gustaaf , Moshchalkov Victor V.
Published: August 2010

Electron spin resonance and electronic spectroscopy techniques were used to study the symmetry and electronic structure of Mn2+ dopants in solvothermally synthesized ZnS nanowires. The average diameter of ∼5 nm leads to the observable quantum confinement effects in the photoluminescence excitation spectra. The results clearly demonstrate the three symmetry locations of Mn2+ incorporation. Together with the inferred Mn2+ center densities, these data indicate a much higher efficiency of Mn2+ substitution in the nanowire sample with about two times larger diameter.
Photoinduced charge transfer and photovoltaic energy conversion in self-assembled N,N′-dioctyl-3,4,9,10-perylenedicarboximide nanoribbons
Authors: Karak S. , Ray S. K. , Dhar A.
Published: August 2010

One-dimensional nanostructures like nanowires, nanoribbons, or nanobelts are attractive building blocks for optoelectronic device applications. Here we report the self-assembly of several micrometer long n-type organic nanoribbons with 100–200 nm of width from N,N′-dioctyl-3,4,9,10-perylenedicarboximide molecules. Significant change in absorption spectra above 550 nm indicates strong π-π stacking along the long axis of nanoribbons. Photovoltaic properties were investigated by mixing them with two well studied donor materials. Strong photoluminescence (PL) quenching and significant decrease in PL life time surmise efficient photoinduced charge transfer and exciton dissociation between nanostructures and donor materials, which leads to a power conversion efficiency of about 1%.
Multiwavelength micro-Raman analysis of strain in nanopatterned ultrathin strained silicon-on-insulator
Authors: Moutanabbir O. , Reiche M. , Hähnel A. , Oehme M. , Kasper E.
Published: August 2010

We developed a heterostructure to assess accurately the strain evolution upon nanopatterning of 15 nm thick tensile strained silicon-on-insulator (SSOI). Here the long-standing concern of substrate background in micro-Raman analysis was circumvented by the introduction of a Ge layer underneath the buried oxide. Unprecedented insights into the strain behavior in SSOI nanostructures were obtained by combining deep UV and visible micro-Raman probes. We found that the formation of edges results in a strong relaxation near the surface parallel to an increase in the strain at the Si/oxide interface. This disparity in the strain evolution between surface and interface leads to the coexistence of compressive and tensile strained regions within the same structure at a lateral dimension of 50 nm. This heterogeneous distribution of strain should be taken into account in the design and fabrication of SSOI-based nanodevices.
Electrically controlled magnetization switching in a multiferroic heterostructure
Authors: Chen Yajie , Fitchorov Trifon , Vittoria Carmine , Harris V. G.
Published: August 2010

A demonstration of magnetization reversal via the application of electric field across a multiferroic heterostructure, consisting of a FeCoV ribbon bonded to a lead magnesium niobate-lead titanate crystal, is presented. The magnetization switching occurs by an abrupt change in magnetization near ferromagnetic coercivity, coinciding with an electrical field-induced magnetic anisotropy field. Experiments reveal a converse magnetoelectric coupling of α=μ0(dM/dE)=1.6×10−7 s m−1 upon magnetization reversal in the strain-mediated heterostructure. The frequency dependence of magnetization switching is presented and explained within the framework of a relaxation model for the multiferroic heterostructure.
Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa
Authors: De Filippo Carlotta , Cavalieri Duccio , Di Paola Monica , Ramazzotti Matteo , Poullet Jean Baptiste , Massart Sebastien , Collini Silvia , Pieraccini Giuseppe , Lionetti Paolo
Published: August 2010

Gut microbial composition depends on different dietary habits just as health depends on microbial metabolism, but the association of microbiota with different diets in human populations has not yet been shown. In this work, we compared the fecal microbiota of European children (EU) and that of children from a rural African village of Burkina Faso (BF), where the diet, high in fiber content, is similar to that of early human settlements at the time of the birth of agriculture. By using high-throughput 16S rDNA sequencing and biochemical analyses, we found significant differences in gut microbiota between the two groups. BF children showed a significant enrichment in Bacteroidetes and depletion in Firmicutes (
P
< 0.001), with a unique abundance of bacteria from the genus
Prevotella
and
Xylanibacter
, known to contain a set of bacterial genes for cellulose and xylan hydrolysis, completely lacking in the EU children. In addition, we found significantly more short-chain fatty acids (
P
< 0.001) in BF than in EU children. Also,
Enterobacteriaceae
(
Shigella
and
Escherichia)
were significantly underrepresented in BF than in EU children (
P
< 0.05). We hypothesize that gut microbiota coevolved with the polysaccharide-rich diet of BF individuals, allowing them to maximize energy intake from fibers while also protecting them from inflammations and noninfectious colonic diseases. This study investigates and compares human intestinal microbiota from children characterized by a modern western diet and a rural diet, indicating the importance of preserving this treasure of microbial diversity from ancient rural communities worldwide.
CARMEN: a practical approach to metadata management
Authors: Jessop Mark , Weeks Mike , Austin Jim
Published: August 2010

The Code Analysis Repository & Modelling for E-Neuroscience (CARMEN) project aims to enable broad sharing of resources, through the provision of a secure, online environment for storage and curation of data, analysis code and experimental protocols, together with the ability to execute data analysis. While the CARMEN system is initially focused on electrophysiology data, it is equally applicable to many domains outside neuroscience.

Metadata are essential for a system such as CARMEN that has the potential to store thousands of data collections and analysis codes; without metadata, resource discovery, interpretation, evaluation and re-use would be severely impeded. Therefore, when any resource (data, service or workflow) is added to the system, users must provide adequate descriptions. These descriptions form a metadata repository that is searchable to allow users to find any kind of resource held in the system, assuming that the user has appropriate access rights.

This paper discusses and explores the project’s approach to implementing such a metadata repository that meets both system requirements and user expectations. Initial approaches were refined after user evaluations, and a more practical approach was followed that better aligned with the aims of the users and the project as a whole.
Adoption and use of Web 2.0 in scholarly communications
Authors: Procter Rob , Williams Robin , Stewart James , Poschen Meik , Snee Helene , Voss Alex , Asgari-Targhi Marzieh
Published: August 2010

Sharing research resources of different kinds, in new ways, and on an increasing scale, is a central element of the unfolding e-Research vision. Web 2.0 is seen as providing the technical platform to enable these new forms of scholarly communications. We report findings from a study of the use of Web 2.0 services by UK researchers and their use in novel forms of scholarly communication. We document the contours of adoption, the barriers and enablers, and the dynamics of innovation in Web services and scholarly practices. We conclude by considering the steps that different stakeholders might take to encourage greater experimentation and uptake.
A new application for the Grid: muon ionization cooling for a Neutrino Factory
Authors: Forrest David , Soler F. J. P.
Published: August 2010

The muon ionization cooling experiment (MICE) will demonstrate a new technique for reducing the transverse emittance of a beam of muon particles, which are a species of lepton heavier than the electron species, essential for the realization of a future Neutrino Factory research facility. The first use of the Grid within MICE was to run thousands of Monte Carlo simulations to determine the alignment and statistical errors associated with measurements in MICE, which are made at two points in space on a similar sample of particles. The results of this study quantified the effect of correlations between emittance measurements. As a consequence, it has been determined that an order of magnitude less muons are required to achieve the required statistical accuracy than assuming uncorrelated measurements. This first application of the Grid within the MICE experimental domain has yielded results that could significantly impact upon the necessary running time of the experiment.
On the psychology of cooperation in humans and other primates: combining the natural history and experimental evidence of prosociality
Authors: Jaeggi Adrian V. , Burkart Judith M. , Van Schaik Carel P.
Published: August 2010

In any given species, cooperation involves prosocial acts that usually return a fitness benefit to the actor. These acts are produced by a set of psychological rules, which will be similar in related species if they have a similar natural history of cooperation. Prosocial acts can be (i)reactive, i.e. in response to specific stimuli, or (ii)proactive, i.e. occur in the absence of such stimuli. We propose that reactive prosocial acts reflect sensitivity to (i) signals or signs of need and (ii) the presence and size of an audience, as modified by (iii) social distance to the partner or partners. We examine the evidence for these elements in humans and other animals, especially non-human primates, based on the natural history of cooperation, quantified in the context of food sharing, and various experimental paradigms. The comparison suggests that humans share with their closest living relatives reactive responses to signals of need, but differ in sensitivity to signs of need and cues of being watched, as well as in the presence of proactive prosociality. We discuss ultimate explanations for these derived features, in particular the adoption of cooperative breeding as well as concern for reputation and costly signalling during human evolution.
Cooperation beyond the dyad: on simple models and a complex society
Authors: Connor Richard C.
Published: August 2010

Players in Axelrod and Hamilton's model of cooperation were not only in a Prisoner's Dilemma, but by definition, they were also trapped in a dyad. But animals are rarely so restricted and even the option to interact with third parties allows individuals to escape from the Prisoner's Dilemma into a much more interesting and varied world of cooperation, from the apparently rare ‘parcelling’ to the widespread phenomenon of market effects. Our understanding of by-product mutualism, pseudo-reciprocity and the snowdrift game is also enriched by thinking ‘beyond the dyad’. The concepts of by-product mutualism and pseudo-reciprocity force us to think again about our basic definitions of cooperative behaviour (behaviour by a single individual) and cooperation (the outcome of an interaction between two or more individuals). Reciprocity is surprisingly rare outside of humans, even among large-brained ‘intelligent’ birds and mammals. Are humans unique in having extensive cooperative interactions among non-kin and an integrated cognitive system for mediating reciprocity? Perhaps, but our best chance for finding a similar phenomenon may be in delphinids, which also live in large societies with extensive cooperative interactions among non-relatives. A system of nested male alliances in bottlenose dolphins illustrates the potential and difficulties of finding a complex system of cooperation close to our own.
Hormonal mechanisms of cooperative behaviour
Authors: Soares Marta C. , Bshary Redouan , Fusani Leonida , Goymann Wolfgang , Hau Michaela , Hirschenhauser Katharina , Oliveira Rui F.
Published: August 2010

Research on the diversity, evolution and stability of cooperative behaviour has generated a considerable body of work. As concepts simplify the real world, theoretical solutions are typically also simple. Real behaviour, in contrast, is often much more diverse. Such diversity, which is increasingly acknowledged to help in stabilizing cooperative outcomes, warrants detailed research about the proximate mechanisms underlying decision-making. Our aim here is to focus on the potential role of neuroendocrine mechanisms on the regulation of the expression of cooperative behaviour in vertebrates. We first provide a brief introduction into the neuroendocrine basis of social behaviour. We then evaluate how hormones may influence known cognitive modules that are involved in decision-making processes that may lead to cooperative behaviour. Based on this evaluation, we will discuss specific examples of how hormones may contribute to the variability of cooperative behaviour at three different levels: (i) within an individual; (ii) between individuals and (iii) between species. We hope that these ideas spur increased research on the behavioural endocrinology of cooperation.
The interplay of cognition and cooperation
Authors: Brosnan Sarah F. , Salwiczek Lucie , Bshary Redouan
Published: August 2010

Cooperation often involves behaviours that reduce immediate payoffs for actors. Delayed benefits have often been argued to pose problems for the evolution of cooperation because learning such contingencies may be difficult as partners may cheat in return. Therefore, the ability to achieve stable cooperation has often been linked to a species' cognitive abilities, which is in turn linked to the evolution of increasingly complex central nervous systems. However, in their famous 1981 paper, Axelrod and Hamilton stated that in principle even bacteria could play a tit-for-tat strategy in an iterated Prisoner's Dilemma. While to our knowledge this has not been documented, interspecific mutualisms are present in bacteria, plants and fungi. Moreover, many species which have evolved large brains in complex social environments lack convincing evidence in favour of reciprocity. What conditions must be fulfilled so that organisms with little to no brainpower, including plants and single-celled organisms, can, on average, gain benefits from interactions with partner species? On the other hand, what conditions favour the evolution of large brains and flexible behaviour, which includes the use of misinformation and so on? These questions are critical, as they begin to address why cognitive complexity would emerge when ‘simple’ cooperation is clearly sufficient in some cases. This paper spans the literature from bacteria to humans in our search for the key variables that link cooperation and deception to cognition.
Apoptosis of leukocytes triggered by acute DNA damage promotes lymphoma formation
Authors: Labi Verena , Erlacher Miriam , Krumschnabel Gerhard , Manzl Claudia , Tzankov Alexandar , Pinon Josephina , Egle Alexander , Villunger Andreas
Published: August 2010

Apoptosis triggered by p53 upon DNA damage secures removal of cells with compromised genomes, and is thought to prevent tumorigenesis. In contrast, we provide evidence that p53-induced apoptosis can actively drive tumor formation. Mice defective in p53-induced apoptosis due to loss of its proapoptotic target gene, puma, resist γ-irradiation (IR)-induced lymphomagenesis. In wild-type animals, repeated irradiation injury-induced expansion of hematopoietic stem/progenitor cells (HSCs) leads to lymphoma formation. Puma−/− HSCs, protected from IR-induced cell death, show reduced compensatory proliferation and replication stress-associated DNA damage, and fail to form thymic lymphomas, demonstrating that the maintenance of stem/progenitor cell homeostasis is critical to prevent IR-induced tumorigenesis.
miR-451 protects against erythroid oxidant stress by repressing 14-3-3ζ
Authors: Yu Duonan , dos Santos Camila O. , Zhao Guowei , Jiang Jing , Amigo Julio D. , Khandros Eugene , Dore Louis C. , Yao Yu , D'Souza Janine , Zhang Zhe , Ghaffari Saghi , Choi John , Friend Sherree , Tong Wei , Orange Jordan S. , Paw Barry H. , Weiss Mitchell J.
Published: August 2010

The bicistronic microRNA (miRNA) locusmiR-144/451is highly expressed during erythrocyte development, although its physiological roles are poorly understood. We show thatmiR-144/451ablation in mice causes mild erythrocyte instability and increased susceptibility to damage after exposure to oxidant drugs. This phenotype is deeply conserved, as miR-451 depletion synergizes with oxidant stress to cause profound anemia in zebrafish embryos. At least some protective activities of miR-451 stem from its ability to directly suppress production of 14-3-3ζ, a phospho-serine/threonine-binding protein that inhibits nuclear accumulation of transcription factor FoxO3, a positive regulator of erythroid anti-oxidant genes. Thus, inmiR-144/451−/−erythroblasts, 14-3-3ζ accumulates, causing partial relocalization of FoxO3 from nucleus to cytoplasm with dampening of its transcriptional program, including anti-oxidant-encoding genesCatandGpx1. Supporting this mechanism, overexpression of 14-3-3ζ in erythroid cells and fibroblasts inhibits nuclear localization and activity of FoxO3. Moreover, shRNA suppression of 14-3-3ζ protectsmiR-144/451−/−erythrocytes against peroxide-induced destruction, and restores catalase activity. Our findings define a novel miRNA-regulated pathway that protects erythrocytes against oxidant stress, and, more generally, illustrate how a miRNA can influence gene expression by altering the activity of a key transcription factor.
Defective erythroid differentiation in miR-451 mutant mice mediated by 14-3-3ζ
Authors: Patrick David M. , Zhang Cheng C. , Tao Ye , Yao Huiyu , Qi Xiaoxia , Schwartz Robert J. , Jun-Shen Huang Lily , Olson Eric N.
Published: August 2010

Erythrocyte formation occurs throughout life in response to cytokine signaling. We show that microRNA-451 (miR-451) regulates erythropoiesis in vivo. Mice lacking miR-451 display a reduction in hematrocrit, an erythroid differentiation defect, and ineffective erythropoiesis in response to oxidative stress. 14-3-3ζ, an intracellular regulator of cytokine signaling that is repressed by miR-451, is up-regulated inmiR-451−/−erythroblasts, and inhibition of 14-3-3ζ rescues their differentiation defect. These findings reveal an essential role of 14-3-3ζ as a mediator of the proerythroid differentiation actions of miR-451, and highlight the therapeutic potential of miR-451 inhibitors.
Antisense oligonucleotides and spinal muscular atrophy: skipping along: Figure 1.
Authors: Burghes Arthur H.M. , McGovern Vicki L.
Published: August 2010

Antisense oligonucleotides (ASOs) can be used to alter the splicing of a gene and either restore production of a required protein or eliminate a toxic product. In this issue of Genes & Development, Hua and colleagues (pp. 1634–1644) show that ASOs directed against an intron splice silencer (ISS) in the survival motor neuron 2 (SMN2) gene alter the amount of full-length SMN transcript in the nervous system, restoring SMN to levels that could correct spinal muscular atrophy (SMA).