bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlated growth of organic material tris (8-hydroxyquinoline) aluminum (Alq3) and its relation to optical properties
Authors: Kanchibotla Bhargava R. , Garre K. , Aurongzeb Deeder
Published: November 2009

We report slow correlated growth mode in energetic cluster vapor deposited organic light emissive material tris(8-hydroxyquinoline) aluminum from 5 to 100 nm. Phase modulated atomic force microscopy shows very slow grain growth with thickness, with very small phase differences within the film. Fractal dimension calculated from correlation function shows growth process above 10 nm consistent with diffusion-limited aggregation. For low thickness (5 nm), photoluminescence measurement shows the emission peak is shifted by ∼0.4 eV toward lower wavelength.
Coengineering of ferroelectric and exchange bias properties in BiFeO3 based heterostructures
Authors: Allibe J. , Infante I. C. , Fusil S. , Bouzehouane K. , Jacquet E. , Deranlot C. , Bibes M. , Barthélémy A.
Published: November 2009

The magnetoelectric coupling existing in some multiferroics may allow the low-power electrical control of spintronics devices. However, room temperature magnetoelectric multiferroics are extremely rare, an exception being BiFeO3, a ferroelectric antiferromagnet. To be used for electrically controllable spintronics, BiFeO3 has to be coupled with a ferromagnetic material through an interfacial exchange interaction, and carefully engineered to show minimum leakage. Here, we propose a Mn doped/undoped bilayer strategy that allows obtaining large exchange bias as well as low leakage. This is an important step toward the manipulation of a magnetization by an electric field in a vertical geometry.
An open-source, extensible system for laboratory timing and control
Authors: Gaskell Peter E. , Thorn Jeremy J. , Alba Sequoia , Steck Daniel A.
Published: November 2009

We describe a simple system for timing and control, which provides control of analog, digital, and radio-frequency signals. Our system differs from most common laboratory setups in that it is open source, built from off-the-shelf components, synchronized to a common and accurate clock, and connected over an Ethernet network. A simple bus architecture facilitates creating new and specialized devices with only moderate experience in circuit design. Each device operates independently, requiring only an Ethernet network connection to the controlling computer, a clock signal, and a trigger signal. This makes the system highly robust and scalable. The devices can all be connected to a single external clock, allowing synchronous operation of a large number of devices for situations requiring precise timing of many parallel control and acquisition channels. Provided an accurate enough clock, these devices are capable of triggering events separated by one day with near-microsecond precision. We have achieved precisions of ∼0.1 ppb (parts per 109) over 16 s.
The friction of a mesh-like super-hydrophobic surface
Authors: Davis Anthony M. J. , Lauga Eric
Published: November 2009

When a liquid droplet is located above a super-hydrophobic surface, it only barely touches the solid portion of the surface, and therefore slides very easily on it. More generally, super-hydrophobic surfaces have been shown to lead to significant reduction in viscous friction in the laminar regime, so it is of interest to quantify their effective slipping properties as a function of their geometric characteristics. Most previous studies considered flows bounded by arrays of either long grooves, or isolated solid pillars on an otherwise flat solid substrate, and for which therefore the surrounding air constitutes the continuous phase. Here we consider instead the case where the super-hydrophobic surface is made of isolated holes in an otherwise continuous no-slip surface, and specifically focus on the mesh-like geometry recently achieved experimentally. We present an analytical method to calculate the friction of such a surface in the case where the mesh is thin. The results for the effective slip length of the surface are computed, compared to simple estimates, and a practical fit is proposed displaying a logarithmic dependence on the area fraction of the solid surface.
Convective instabilities in liquid layers with free upper surface under the action of an inclined temperature gradient
Authors: Mizev A. I. , Schwabe D.
Published: November 2009

We present the results of an experimental study of convective instabilities in a horizontal liquid layer with free upper surface under the action of an inclined temperature gradient, i.e., when horizontal and vertical temperature gradients are applied at the same time. Silicone oil of 10 cSt (Prandtl number Pr=102) was employed as the test fluid. We investigated the layers with different thicknesses to examine the influence of gravity on the formation of the convective patterns. It is found out that the system behavior appreciably depends on the dynamic Bond number, which shows a relation of buoyancy and thermocapillary forces. In the case of small dynamic Bond numbers, when the influence of buoyancy is minimal, four different flow patterns, according to the combination of the vertical and horizontal Marangoni numbers, have been found: steady parallel flow, Bénard–Marangoni cells, drifting Bénard–Marangoni cells, and longitudinal rolls. At larger dynamic Bond number, when the influence of buoyancy becomes considerable, new convective structures, named by us the “surface longitudinal rolls” and the “surface drifting cells,” appear in addition to the patterns listed above. These instabilities exist only in the surface part of the thermocapillary flow, whereas the return flow remains stable. Under large enough dynamic Bond number these patterns become the dominating ones, forcing out the classical Bénard–Marangoni instability. We give a phenomenological description of the obtained convective patterns and present the stability diagram in the plane of the vertical and the horizontal Marangoni numbers.
Dielectric discontinuity effects on the adsorption of a linear polyelectrolyte at the surface of a neutral nanoparticle
Authors: Seijo Marianne , Pohl Martin , Ulrich Serge , Stoll Serge
Published: November 2009

The formation of complexes between nanoparticles and polyelectrolytes is a key process for the control of the reactivity of manufactured nanoparticles and rational design of core shell nanostructures. In this work, we investigate the influence of the nanoparticle dielectric constant on the adsorption of a linear charged polymer (polyelectrolyte) at the surface of a neutral nanoparticle. The polyelectrolyte linear charge density, as well as the image charges in the nanoparticle due to the dielectric discontinuity, is taken into account. Monte Carlo simulations are used to predict the adsorption/desorption limits and system properties. Effects of the nanoparticle size and polyelectrolyte length are also investigated. The polyelectrolyte is found adsorbed on the nanoparticle when the dielectric constant of the nanoparticle is greater than the dielectric constant of the medium. Attractive interactions induced by the presence of opposite sign image charges are found strong enough to adsorb the polyelectrolyte showing that the reaction field contribution has to be considered. The affinity between the polyelectrolyte and the nanoparticle is found to increase in magnitude by increasing the nanoparticle size and dielectric constant. The reaction field magnitude is also found to depend in a nonlinear way from the polyelectrolyte length.
Improving Levine model for dielectric constants of transition metal compounds
Authors: Li C. , Li J. C. , Lian J. S. , Jiang Q.
Published: November 2009

The density of states and optical properties of several transition metal compounds have been simulated using local density approximations+U. Results show that s electrons of nontransition elements in the compounds cannot be considered to have the same contribution on the number of valence electrons. In light of this observation, the parameter Γ in the Levine model is improved, which leads to better prediction for dielectric constants of transition metal compounds.
Platinum Schottky contacts on single-crystal ZnO with hydrogen peroxide treatment
Authors: Tsai Chia-Hung , Lin Shi-Xiong , Hung Chen-I , Liu Chien-Chih , Houng Mau-Phon
Published: November 2009

Platinum (Pt) Schottky contacts (SCs) on hydrothermal grown Zn-terminated (0001) ZnO substrates with the different hydrogen peroxide (H2O2) treatment time are investigated. Under the treatment in room temperature, effective SCs are made for 45 min and longer time and the electrical characteristics show the dependence on treatment time. The irregular humps on ZnO surface with roughness measured by atomic force microscope differ as the treatment time and roughness exhibits the large variation between 0.368 and 3.566 nm, indicating the etching effect and near-surface defects related to the lattice imperfections. The evaluated barrier height has the value at 0.89–0.96 eV with the saturation current density in the range of 2.21×10−10–3.31×10−9 A/cm2. The effective donor concentration calculated from capacitance-voltage (C-V) measurement decreases as treatment time, implying the widening of the space charge region after H2O2 treatment. The improved SC characteristics are attributed to the product of the wider bandgap and low-conductivity ZnO2 via grazing-incidence x-ray diffraction analysis. The rectifying behavior has the threshold dependence on the treatment time and has the reverse trend toward the surface asperities.
Vibrational circular dichroism signal enhancement using self-heterodyning with elliptically polarized laser pulses
Authors: Helbing Jan , Bonmarin Mathias
Published: November 2009

Vibrational circular dichroism (VCD) spectra were recorded using elliptically polarized ultrashort laser pulses, produced with the help of a photoelastic modulator. The short polarization axis of the elliptical light acts as a phase-locked local oscillator field, heterodyning the chiral signal generated by the field along the long polarization axis. This leads to VCD signals that increase linearly with the ellipticity of the probe pulses and enhanced signal to noise, which is expected to improve recently reported transient VCD scans. An analogous scheme allows for vibrational optical rotary dispersion measurements. The techniques are compared with similar approaches using both a linear response picture and the Jones matrix calculus.
Single-shot measurement of terahertz temporal waveform using pulse-front tilting by a direct vision dispersion prism
Authors: Kawada Yoichi , Yasuda Takashi , Nakanishi Atsushi , Takahashi Hironori , Aoshima Shin-ichiro
Published: November 2009

We demonstrated a single-shot measurement of terahertz temporal waveform using pulse-front tilting by a direct vision dispersion prism (DVDP). An advantage of this technique is the simplicity with which an electro-optic terahertz imaging optical system can be changed into a single-shot measurement system by inserting a DVDP in the probe beam path. In this technique, control of the angle of pulse-front tilting is very important. We precisely designed DVDP and measured the angle of the pulse-front tilting by interference measurement. We obtained a terahertz temporal waveform with a single shot with a time window of 3.2 ps.
A unified sweep-stick mechanism to explain particle clustering in two- and three-dimensional homogeneous, isotropic turbulence
Authors: Coleman S. W. , Vassilicos J. C.
Published: November 2009

Our work focuses on the sweep-stick mechanism of particle clustering in turbulent flows introduced by Chen et al. [L. Chen, S. Goto, and J. C. Vassilicos, “Turbulent clustering of stagnation points and inertial particles,” J. Fluid Mech. 553, 143 (2006)] for two-dimensional (2D) inverse cascading homogeneous, isotropic turbulence (HIT), whereby heavy particles cluster in a way that mimics the clustering of zero-acceleration points. We extend this phenomenology to three-dimensional (3D) HIT, where it was previously reported that zero-acceleration points were extremely rare. Having obtained a unified mechanism we quantify the Stokes number dependency of the probability of the heavy particles to be at zero-acceleration points and show that in the inertial range of Stokes numbers, the sweep-stick mechanism is dominant over the conventionally proposed mechanism of heavy particles being centrifuged from high vorticity regions to high strain regions. Finally, having a clustering coincidence between particles and zero-acceleration points, both in 2D and 3D HIT, motivates us to demonstrate the sweep and stick parts of the mechanism in both dimensions. The sweeping of regions of low acceleration regions by the local fluid velocity in both flows is demonstrated by introducing a velocity of the acceleration field. Finally, the stick part is demonstrated by showing that heavy particles statistically move with the same velocity as zero-acceleration points, while moving away from any nonzero-acceleration region, irrespective of their Stokes number. These results explain the clustering of inertial particles given the clustering of zero-acceleration points.
Comparison of the resonance-enhanced multiphoton ionization spectra of pyrrole and 2,5-dimethylpyrrole: Building toward an understanding of the electronic structure and photochemistry of porphyrins
Authors: Beames Joseph M. , Nix Michael G. D. , Hudson Andrew J.
Published: November 2009

The photophysical properties of porphyrins have relevance for their use as light-activated drugs in cancer treatment and sensitizers in solid-state solar cells. However, the appearance of their UV-visible spectra is usually explained inadequately by qualitative molecular-orbital theories. We intend to gain a better insight into the intense absorption bands, and excited-state dynamics, that make porphyrins appropriate for both of these applications by gradually building toward an understanding of the macrocyclic structure, starting with studies of smaller pyrrolic subunits. We have recorded the (1+1) and (2+1) resonance-enhanced multiphoton ionization (REMPI) spectra of pyrrole and 2,5-dimethylpyrrole between 25 600 cm−1 (390 nm) and 48 500 cm−1 (206 nm). We did not observe a (1+1) REMPI signal through the optically bright B12 (ππ∗) and A11 (ππ∗) states in pyrrole due to ultrafast deactivation via conical intersections with the dissociative A12 (πσ∗) and B11 (πσ∗) states. However, we did observe (2+1) REMPI through Rydberg states with a dominant feature at 27 432 cm−1 (two-photon energy, 54 864 cm−1) assigned to a 3d←π transition. In contrast, 2,5-dimethylpyrrole has a broad and structured (1+1) REMPI spectrum between 36 000 and 42 500 cm−1 as a result of vibronic transitions to the B12 (ππ∗) state, and it does not show the 3d←π Rydberg transition via (2+1) REMPI. We have complemented the experimental studies by a theoretical treatment of the excited states of both molecules using time-dependent density functional theory (TD-DFT) and accounted for the contrasting features in the spectra. TD-DFT modeled the photochemical activity of both the optically dark π1σ∗ states (dissociative) and optically bright π1π∗ states well, predicting the barrierless deactivation of the B12 (ππ∗) state of pyrrole and the bound minimum of the B12 (ππ∗) state in 2,5-dimethylpyrrole. However, the quantitative agreement between vibronic transition energies and the excited-state frequencies calculated by TD-DFT was hampered by inaccurate modeling of Rydberg orbital mixing with the valence states, caused by the lack of an asymptotic correction to the exchange-correlation functionals used.
Fragmentation properties of three-membered heterocyclic molecules by partial ion yield spectroscopy: C2H4O and C2H4S
Authors: Stolte W. C. , Dumitriu I. , Yu S.-W. , Öhrwall G. , Piancastelli M. N. , Lindle D. W.
Published: November 2009

We investigated the photofragmentation properties of two three-membered ring heterocyclic molecules, C2H4O and C2H4S, by total and partial ion yield spectroscopy. Positive and negative ions have been collected as a function of photon energy around the C 1s and O 1s ionization thresholds in C2H4O, and around the S 2p and C 1s thresholds in C2H4S. We underline similarities and differences between these two analogous systems. We present a new assignment of the spectral features around the C K-edge and the sulfur L2,3 edges in C2H4S. In both systems, we observe high fragmentation efficiency leading to positive and negative ions when exciting these molecules at resonances involving core-to-Rydberg transitions. The system, with one electron in an orbital far from the ionic core, relaxes preferentially by spectator Auger decay, and the resulting singly charged ion with two valence holes and one electron in an outer diffuse orbital can remain in excited states more susceptible to dissociation. A state-selective fragmentation pattern is analyzed in C2H4S which leads to direct production of S2+ following the decay of virtual-orbital excitations to final states above the double-ionization threshold.
Composition-dependent dielectric properties of RbTiOPO4 single crystals
Authors: Gavaldà Jna. , Carvajal J. J. , Mateos X. , Aguiló M. , Díaz F.
Published: November 2009

We measured the ionic conductivity for two single crystals of RbTiOPO4 grown in self-fluxes with different chemical composition. Ionic conductivity depended on the composition of the self-flux solution in which the crystal was grown. One of the samples showed an anisotropic behavior along the three crystallographic axes while the other showed a nearly isotropic behavior of the ac conductivity.
Minority electron unipolar photodetectors based on type II InAs/GaSb/AlSb superlattices for very long wavelength infrared detection
Authors: Nguyen B.-M. , Bogdanov S. , Pour S. Abdollahi , Razeghi M.
Published: November 2009

We present a hybrid photodetector design that inherits the advantages of traditional photoconductive and photovoltaic devices. The structure consists of a barrier layer blocking the transport of majority holes in a p-type semiconductor, resulting in an electrical transport due to minority carriers with low current density. By using the M-structure superlattice as a barrier region, the band alignments can be experimentally controlled, allowing for the efficient extraction of the photosignal with less than 50 mV bias. At 77 K, a 14 μm cutoff detector exhibits a dark current 3.3 mA/cm2, a photoresponsivity of 1.4 A/W, and the associated shot noise detectivity of 4×1010 Jones.
Shaping site-controlled uniform arrays of SiGe/Si(001) islands by in situ annealing
Authors: Zhang J. J. , Rastelli A. , Groiss H. , Tersoff J. , Schäffler F. , Schmidt O. G. , Bauer G.
Published: November 2009

We investigate the effect of in situ annealing on the shape, size, and chemical composition of ordered SiGe islands grown on pit-patterned Si(001) substrates. In contrast to planar substrates, intermixing with substrate material occurs symmetrically during annealing because the substrate patterning pins the island position and suppresses lateral motion. The results are consistent with surface-mediated intermixing and demonstrate that annealing is an effective method to tune the island properties with no appreciable deterioration of the ensemble homogeneity.
Erratum: “A partial synchronization theorem” [Chaos 18, 037107 (2008)]
Authors: Pogromsky Alexander Yu.
Published: November 2009

This erratum corrects a mistake previously published by the author [A. Y. Pogromsky, Chaos 18, 037107 (2008)].
Learning by observation requires an early sleep window
Authors: Van Der Werf Ysbrand D. , Van Der Helm Els , Schoonheim Menno M. , Ridderikhoff Arne , Van Someren Eus J. W.
Published: November 2009

Numerous studies have shown that sleep enhances memory for motor skills learned through practice. Motor skills can, however, also be learned through observation, a process possibly involving the mirror neuron system. We investigated whether motor skill enhancement through prior observation requires sleep to follow the observation, either immediately or after a delay, to consolidate the procedural memory. Sequence-specific fingertapping performance was tested in 64 healthy subjects in a balanced design. Electromyography verified absence of overt or subliminal hand muscle activations during observation. The results show that immediate sleep is necessary for the enhancement of a motor skill through prior observation. Immediate sleep improved the speed of subsequent performance by 22 ± 11% (mean ± SEM) (
P
= 0.04) and reduced the error rate by 42 ± 19% (
P
= 0.02). In contrast, no performance gains occurred if sleep was initiated more than 12 h after observation. A second study on 64 subjects ruled out explicit familiarity with the sequence or the spatiotemporal rhythm of the sequence to underlie performance improvements. The sleep-dependent observational motor learning enhancement is at least similar to that previously reported for implicit and declarative memory. The apparent prerequisite of observing real movements indicates that subjects transfer experience obtained through observation of movements to subsequent self-initiated movements, in the absence of practice. Moreover, the consolidation of this transfer requires an early sleep window. These findings could improve learning new motor skills in athletes and children, but also in patients having to remaster skills following stroke or injury.
Cooperation and individuality among man-eating lions
Authors: Yeakel Justin D. , Patterson Bruce D. , Fox-Dobbs Kena , Okumura Mercedes M. , Cerling Thure E. , Moore Jonathan W. , Koch Paul L. , Dominy Nathaniel J.
Published: November 2009

Cooperation is the cornerstone of lion social behavior. In a notorious case, a coalition of two adult male lions from Tsavo, southern Kenya, cooperatively killed dozens of railway workers in 1898. The “man-eaters of Tsavo” have since become the subject of numerous popular accounts, including three Hollywood films. Yet the full extent of the lions' man-eating behavior is unknown; estimates range widely from 28 to 135 victims. Here we use stable isotope ratios to quantify increasing dietary specialization on novel prey during a time of food limitation. For one lion, the δ
13
C and δ
15
N values of bone collagen and hair keratin (which reflect dietary inputs over years and months, respectively) reveal isotopic changes that are consistent with a progressive dietary specialization on humans. These findings not only support the hypothesis that prey scarcity drives individual dietary specialization, but also demonstrate that sustained dietary individuality can exist within a cooperative framework. The intensity of human predation (up to 30% reliance during the final months of 1898) is also associated with severe craniodental infirmities, which may have further promoted the inclusion of unconventional prey under perturbed environmental conditions.
Sustained delivery of thermostabilized chABC enhances axonal sprouting and functional recovery after spinal cord injury
Authors: Lee Hyunjung , McKeon Robert J. , Bellamkonda Ravi V.
Published: November 2009

Chondroitin sulfate proteoglycans (CSPGs) are a major class of axon growth inhibitors that are up-regulated after spinal cord injury (SCI) and contribute to regenerative failure. Chondroitinase ABC (chABC) digests glycosaminoglycan chains on CSPGs and can thereby overcome CSPG-mediated inhibition. But chABC loses its enzymatic activity rapidly at 37 °C, necessitating the use of repeated injections or local infusions for a period of days to weeks. These infusion systems are invasive, infection-prone, and clinically problematic. To overcome this limitation, we have thermostabilized chABC and developed a system for its sustained local delivery in vivo, obviating the need for chronically implanted catheters and pumps. Thermostabilized chABC remained active at 37 °C in vitro for up to 4 weeks. CSPG levels remained low in vivo up to 6 weeks post-SCI when thermostabilized chABC was delivered by a hydrogel-microtube scaffold system. Axonal growth and functional recovery following the sustained local release of thermostabilized chABC versus a single treatment of unstabilized chABC demonstrated significant differences in CSPG digestion. Animals treated with thermostabilized chABC in combination with sustained neurotrophin-3 delivery showed significant improvement in locomotor function and enhanced growth of cholera toxin B subunit–positive sensory axons and sprouting of serotonergic fibers. Therefore, improving chABC thermostability facilitates minimally invasive, sustained, local delivery of chABC that is potentially effective in overcoming CSPG-mediated regenerative failure. Combination therapy with thermostabilized chABC with neurotrophic factors enhances axonal regrowth, sprouting, and functional recovery after SCI.
Glacier loss on Kilimanjaro continues unabated
Authors: Thompson L. G. , Brecher H. H. , Mosley-Thompson E. , Hardy D. R. , Mark B. G.
Published: November 2009

The dramatic loss of Kilimanjaro's ice cover has attracted global attention. The three remaining ice fields on the plateau and the slopes are both shrinking laterally and rapidly thinning. Summit ice cover (areal extent) decreased ≈1% per year from 1912 to 1953 and ≈2.5% per year from 1989 to 2007. Of the ice cover present in 1912, 85% has disappeared and 26% of that present in 2000 is now gone. From 2000 to 2007 thinning (surface lowering) at the summits of the Northern and Southern Ice Fields was ≈1.9 and ≈5.1 m, respectively, which based on ice thicknesses at the summit drill sites in 2000 represents a thinning of ≈3.6% and ≈24%, respectively. Furtwängler Glacier thinned ≈50% at the drill site between 2000 and 2009. Ice volume changes (2000–2007) calculated for two ice fields reveal that nearly equivalent ice volumes are now being lost to thinning and lateral shrinking. The relative importance of different climatological drivers remains an area of active inquiry, yet several points bear consideration. Kilimanjaro's ice loss is contemporaneous with widespread glacier retreat in mid to low latitudes. The Northern Ice Field has persisted at least 11,700 years and survived a widespread drought ≈4,200 years ago that lasted ≈300 years. We present additional evidence that the combination of processes driving the current shrinking and thinning of Kilimanjaro's ice fields is unique within an 11,700-year perspective. If current climatological conditions are sustained, the ice fields atop Kilimanjaro and on its flanks will likely disappear within several decades.
Sodium shortage as a constraint on the carbon cycle in an inland tropical rainforest
Authors: Kaspari Michael , Yanoviak Stephen P. , Dudley Robert , Yuan May , Clay Natalie A.
Published: November 2009

Sodium (Na) is uncommon in plants but essential to the metabolism of plant consumers, both decomposers and herbivores. One consequence, previously unexplored, is that as Na supplies decrease (e.g., from coastal to inland forests), ecosystem carbon should accumulate as detritus. Here, we show that adding NaCl solution to the leaf litter of an inland Amazon forest enhanced mass loss by 41%, decreased lignin concentrations by 7%, and enhanced decomposition of pure cellulose by up to 50%, compared with stream water alone. These effects emerged after 13–18 days. Termites, a common decomposer, increased 7-fold on +NaCl plots, suggesting an agent for the litter loss. Ants, a common predator, increased 2-fold, suggesting that NaCl effects cascade upward through the food web. Sodium, not chloride, was likely the driver of these patterns for two reasons: two compounds of Na (NaCl and NaPO4) resulted in equivalent cellulose loss, and ants in choice experiments underused Cl (as KCl, MgCl2, and CaCl2) relative to NaCl and three other Na compounds (NaNO3, Na3PO4, and Na2SO4). We provide experimental evidence that Na shortage slows the carbon cycle. Because 80% of global landmass lies >100 km inland, carbon stocks and consumer activity may frequently be regulated via Na limitation.
Adoptive therapy with redirected primary regulatory T cells results in antigen-specific suppression of arthritis
Authors: Wright Graham P. , Notley Clare A. , Xue Shao-An , Bendle Gavin M. , Holler Angelika , Schumacher Ton N. , Ehrenstein Michael R. , Stauss Hans J.
Published: November 2009

Regulatory T cells (Tregs) can suppress a wide range of immune cells, making them an ideal candidate for the treatment of autoimmunity. The potential clinical translation of targeted therapy with antigen-specific Tregs is hampered by the difficulties of isolating rare specificities from the natural polyclonal T cell repertoire. Moreover, the initiating antigen is often unknown in autoimmune disease. Here we tested the ability of antigen-specific Tregs generated by retroviral gene transfer to ameliorate arthritis through linked suppression and therefore without cognate recognition of the disease-initiating antigen. We explored two distinct strategies: T cell receptor (TCR) gene transfer into purified CD4+CD25+ T cells was used to redirect the specificity of naturally occurring Tregs; and co-transfer of FoxP3 and TCR genes served to convert conventional CD4+T cells into antigen-specific regulators. Following adoptive transfer into recipient mice, the gene-modified T cells engrafted efficiently and retained TCR and FoxP3 expression. Using an established arthritis model, we demonstrate antigen-driven accumulation of the gene modified T cells at the site of joint inflammation, which resulted in a local reduction in the number of inflammatory Th17 cells and a significant decrease in arthritic bone destruction. Together, we describe a robust strategy to rapidly generate antigen-specific regulatory T cells capable of highly targeted inhibition of tissue damage in the absence of systemic immune suppression. This opens the possibility to target Tregs to tissue-specific antigens for the treatment of autoimmune tissue damage without the knowledge of the disease-causing autoantigens recognized by pathogenic T cells.
HDAC6 is a target for protection and regeneration following injury in the nervous system
Authors: Rivieccio Mark A. , Brochier Camille , Willis Dianna E. , Walker Breset A. , D'Annibale Melissa A. , McLaughlin Kathryn , Siddiq Ambreena , Kozikowski Alan P. , Jaffrey Samie R. , Twiss Jeffery L. , Ratan Rajiv R. , Langley Brett
Published: November 2009

Central nervous system (CNS) trauma can result in tissue disruption, neuronal and axonal degeneration, and neurological dysfunction. The limited spontaneous CNS repair in adulthood and aging is often insufficient to overcome disability. Several investigations have demonstrated that targeting HDAC activity can protect neurons and glia and improve outcomes in CNS injury and disease models. However, the enthusiasm for pan-HDAC inhibition in treating neurological conditions is tempered by their toxicity toward a host of CNS cell types –a biological extension of their anticancer properties. Identification of the HDAC isoform, or isoforms, that specifically mediate the beneficial effects of pan-HDAC inhibition could overcome this concern. Here, we show that pan-HDAC inhibition not only promotes neuronal protection against oxidative stress, a common mediator of injury in many neurological conditions, but also promotes neurite growth on myelin-associated glycoprotein and chondroitin sulfate proteoglycan substrates. Real-time PCR revealed a robust and selective increase in HDAC6 expression due to injury in neurons. Accordingly, we have used pharmacological and genetic approaches to demonstrate that inhibition of HDAC6 can promote survival and regeneration of neurons. Consistent with a cytoplasmic localization, the biological effects of HDAC6 inhibition appear transcription-independent. Notably, we find that selective inhibition of HDAC6 avoids cell death associated with pan-HDAC inhibition. Together, these findings define HDAC6 as a potential nontoxic therapeutic target for ameliorating CNS injury characterized by oxidative stress-induced neurodegeneration and insufficient axonal regeneration.
Telomere capping proteins are structurally related to RPA with an additional telomere-specific domain
Authors: Gelinas Amy D. , Paschini Margherita , Reyes Francis E. , Héroux Annie , Batey Robert T. , Lundblad Victoria , Wuttke Deborah S.
Published: November 2009

Telomeres must be capped to preserve chromosomal stability. The conserved Stn1 and Ten1 proteins are required for proper capping of the telomere, although the mechanistic details of how they contribute to telomere maintenance are unclear. Here, we report the crystal structures of the C-terminal domain of the
Saccharomyces cerevisiae
Stn1 and the
Schizosaccharomyces pombe
Ten1 proteins. These structures reveal striking similarities to corresponding subunits in the replication protein A complex, further supporting an evolutionary link between telomere maintenance proteins and DNA repair complexes. Our structural and in vivo data of Stn1 identify a new domain that has evolved to support a telomere-specific role in chromosome maintenance. These findings endorse a model of an evolutionarily conserved mechanism of DNA maintenance that has developed as a result of increased chromosomal structural complexity.
Genetic variations in peroxisome proliferator-activated receptor γ expression affect blood pressure
Authors: Tsai Yau-Sheng , Xu Lonquan , Smithies Oliver , Maeda Nobuyo
Published: November 2009

Metabolic syndrome, a clustering of conditions including obesity, insulin resistance, and hypertension, is a risk factor for cardiovascular morbidity and mortality. Because peroxisome proliferator-activated receptor γ (PPARγ) regulates adipocyte differentiation and lipid metabolism and is the molecular target of a class of insulin sensitizers, genetic variants that alter
Pparg
gene expression are potential contributors to the metabolic syndrome. To test this possibility, we generated mice having 182% of the normal steady-state level of PPARγ mRNA by replacing the 3′-UTR of the natural
Pparg
gene with that of the β-globin gene, thereby stabilizing the
Pparg
transcripts. This increase in PPARγ mRNA level had no apparent consequences in various physiological parameters, except that the mice repeatedly showed a trend toward lower blood pressures (by about 3 mm Hg) than their WT littermates. In contrast, the opposite trend, toward increased blood pressure, was observed in mice with genetically reduced levels of PPARγ mRNA as a consequence of insertion of an allele with an mRNA-destabilizing sequence into the endogenous 3′-UTR of the
Pparg
gene. By combining 12 sets of blood pressure measurements in more than 350 mutant mice having PPARγ expression levels varying from 28% to 182% and more than 280 WT littermates, we show that a 2-fold genetic increase (or decrease) in PPARγ expression levels decreases (or increases) blood pressure by about 2.8 mm Hg. Thus, our experiments demonstrate that quantitative variants causing decreased
Pparg
expression are a potential causative risk factor for essential hypertension.
Geographic patterns of
Plasmodium falciparum
drug resistance distinguished by differential responses to amodiaquine and chloroquine
Authors: Sá Juliana Martha , Twu Olivia , Hayton Karen , Reyes Sahily , Fay Michael P. , Ringwald Pascal , Wellems Thomas E.
Published: November 2009

Chloroquine (CQ) resistance (CQR) in
Plasmodium falciparum
originated from at least six foci in South America, Asia, and Oceania. Malaria parasites from these locations exhibit contrasting resistance phenotypes that are distinguished by point mutations and microsatellite polymorphisms in and near the CQR transporter gene,
pfcrt
, and the multidrug resistance transporter gene,
pfmdr1
. Amodiaquine (AQ), a 4-aminoquinoline related to CQ, is recommended and often used successfully against CQ-resistant
P. falciparum
in Africa, but it is largely ineffective across large regions of South America. The relationship of different
pfcrt
and
pfmdr1
combinations to these drug-resistant phenotypes has been unclear. In two
P. falciparum
genetic crosses, particular
pfcrt
and
pfmdr1
alleles from South America interact to yield greater levels of resistance to monodesethylamodiaquine (MDAQ; the active metabolite of AQ) than to CQ, whereas a
pfcrt
allele from Southeast Asia and Africa is linked to greater CQ than MDAQ resistance with all partner
pfmdr1
alleles. These results, together with (
i
) available haplotype data from other parasites; (
ii
) evidence for an emerging focus of AQ resistance in Tanzania; and (
iii
) the persistence of 4-aminoquinoline-resistant parasites in South America, where CQ and AQ use is largely discontinued, suggest that different histories of drug use on the two continents have driven the selection of distinct suites of
pfcrt
and
pfmdr1
mutations. Increasing use of AQ in Africa poses the threat of a selective sweep of highly AQ-resistant, CQ-resistant parasites with
pfcrt
and
pfmdr1
mutations that are as advantaged and persistent as in South America.
Niche recycling through division-independent egress of hematopoietic stem cells
Authors: Bhattacharya Deepta , Czechowicz Agnieszka , Ooi A.G. Lisa , Rossi Derrick J. , Bryder David , Weissman Irving L.
Published: November 2009

Hematopoietic stem cells (HSCs) are thought to reside in discrete niches through stable adhesion, yet previous studies have suggested that host HSCs can be replaced by transplanted donor HSCs, even in the absence of cytoreductive conditioning. To explain this apparent paradox, we calculated, through cell surface phenotyping and transplantation of unfractionated blood, that ∼1–5% of the total pool of HSCs enters into the circulation each day. Bromodeoxyuridine (BrdU) feeding experiments demonstrated that HSCs in the peripheral blood incorporate BrdU at the same rate as do HSCs in the bone marrow, suggesting that egress from the bone marrow to the blood can occur without cell division and can leave behind vacant HSC niches. Consistent with this, repetitive daily transplantations of small numbers of HSCs administered as new niches became available over the course of 7 d led to significantly higher levels of engraftment than did large, single-bolus transplantations of the same total number of HSCs. These data provide insight as to how HSC replacement can occur despite the residence of endogenous HSCs in niches, and suggest therapeutic interventions that capitalize upon physiological HSC egress.
Implementation of device therapy (cardiac resynchronization therapy and implantable cardioverter defibrillator) for patients with heart failure in Europe: changes from 2004 to 2008
Authors: van Veldhuisen Dirk J. , Maass Alexander H. , Priori Silvia G. , Stolt Pelle , van Gelder Isabelle C. , Dickstein Kenneth , Swedberg Karl
Published: November 2009

Aims

Heart failure (HF) patients increasingly receive device therapy, either an implantable cardioverter defibrillator (ICD) or a biventricular pacemaker, also called cardiac resynchronization therapy (CRT), or a CRT device with an ICD (CRT‐D). However, epidemiological data on the use of device therapy in Europe are limited.

Methods and results

Data on implantation rates for conventional pacemakers, ICD, CRT, and CRT‐D in 15 Western European countries were obtained from the Eucomed Registry for the 5‐year period 2004–2008. Implantation of conventional pacemakers increased by 9% in Europe over the 5 years (reaching 907/million in 2008) and there were significant differences between countries. Implantable cardioverter defibrillator implantations increased by 75% from 80/million in 2004 to 140/million in 2008, and differences between countries were larger than those for conventional pacemakers. Implantation rates for CRT‐P alone increased slightly from 2004 to 2006, but remained at 25/million thereafter in Europe overall. The total number of CRT implants (CRT‐P and ‐D) markedly increased from 46/million in 2004 to 99/million in 2008 (115%), but this was mainly due to more CRT‐D implants, i.e. an increase in the proportion of CRT‐D (from 55% in 2004 to 75% in 2008). Implantation rates for ICD, CRT, and CRT‐D remained markedly different throughout the study period between countries.

Conclusion

Implantation rates of devices for HF, in particular ICD and CRT‐D, have increased significantly between 2004 and 2008 in Europe, but there remain major differences between countries.
The biological impact of overflowing sands around a marine aggregate extraction site: Dieppe (eastern English Channel)
Authors: Desprez M. , Pearce B. , Le Bot S.
Published: November 2009

Desprez, M., Pearce, B., and Le Bot, S. 2010. The biological impact of overflowing sands around a marine aggregate extraction site: Dieppe (eastern English Channel). – ICES Journal of Marine Science, 67: 270–277. The study investigates the physical impact of sediment deposition associated with aggregate dredging at a site off Dieppe, and the consequences for benthic fauna. Sampling stations were sited across potential zones of impact classified as high, moderate, and low deposition, depending on their proximity to dredging activities and their position relative to the net sediment transport route. Samples were also taken west of the dredge site outside the zone of likely impact (no deposition). A strong gradient was observed from the sediments dominated by fine sands in the high and moderate deposition zones, through to coarse sands and gravels in the low and no deposition zones. The benthic fauna sampled from the deposits of fine sand in the high and moderate deposition zones were sparse compared with the coarser deposits sampled from the low and no deposition zones. There was a strong correspondence between the distribution of different sediment fractions and the associated benthic fauna, with a weighted Spearman rank correlation of 0.638, higher than reported in related studies. This suggests that in deposition areas such as this, biological interactions play a less important role in shaping communities than the changes in the physical environment, which may have a greater impact on the biological communities.
Correction for Holloway and Harrison, Algal morphogenesis: modelling interspecific variation in
Micrasterias
with reaction–diffusion patterned catalysis of cell surface growth
Authors: Holloway D. M. , Harrison L. G.
Published: November 2009

Correction for ‘Algal morphogenesis: modelling interspecific variation in
Micrasterias
with reaction–diffusion patterned catalysis of cell surface growth’ by D. M. Holloway and L. G. Harrison (Phil. Trans. R. Soc. Lond. B
354
, 417–433.
(doi:
10.1098/rstb.1999.0395
)).

On page 417, the footnotes indicated by the asterisk and dagger were mistakenly reversed.
Correction for Okada, Historical overview of research on the tobacco mosaic virus genome: genome organization, infectivity and gene manipulation
Authors: Okada Y.
Published: November 2009

Correction for ‘Historical overview of research on the tobacco mosaic virus genome: genome organization, infectivity and gene manipulation–diffusion patterned catalysis of cell surface growth’ by Y. Okada (Phil. Trans. R. Soc. Lond. B
354
, 569–582.
(doi:
10.1098/rstb.1999.0408
)).

In the abstract (p. 569) mitochondrial DNA was incorrectly printed insead of mRNA.
Addendum for Uğurbil
et al.
, Functional mapping in the human brain using high magnetic fields
Authors: Uğurbil K. , Wei Chen X. H. , Zhu X.-H. , Kim S.-G. , Georgopoulos A.
Published: November 2009

Addendum for ‘Functional mapping in the human brain using high magnetic fields’ by K. Uğurbil, X. H. Wei Chen, X.-H. Zhu, S.-G. Kim and A. Georgopoulos (Phil. Trans. R. Soc. Lond. B
354
, 1195–1213.
(doi:
10.1098/rstb.1999.0474
)).

In the acknowledgements (p. 1210), the authors have requested that NIH grant number NS 32919 be added.
Correction for Mesulam, Spatial attention and neglect: parietal, frontal and cingulate contributions to the mental representation and attentional targeting of salient extrapersonal events
Authors: Mesulam M.-M.
Published: November 2009

Correction for ‘Spatial attention and neglect: parietal, frontal and cingulate contributions to the mental representation and attentional targeting of salient extrapersonal events’ by M.-M. Mesulam (Phil. Trans. R. Soc. Lond. B
354
, 1325–1346.
(doi:
10.1098/rstb.1999.0482
)).

In the legend to figure 3 (p. 1332), the words left and right were mistakenly transposed.
Sporolactobacillus putidus sp. nov., an endospore-forming lactic acid bacterium isolated from spoiled orange juice
Authors: Fujita Rieko , Mochida Kaoru , Kato Yuko , Goto Keiichi
Published: November 2009

A Gram-positive, endospore-forming, lactic acid bacterium was isolated from spoiled orange juice. The organism, strain QC81-06T, grew microaerobically or anaerobically at 30–45 °C (optimum 35 °C) and pH 3.5–5.5 (optimum pH 4.5), and produced acid from various sugars. d-Lactic acid was produced. It contained menaquinone-7 as the major isoprenoid quinone. The G+C content of the genomic DNA was 47.5 mol%. The predominant cellular fatty acids of the strain were iso-C16 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. Phylogenetic analyses based on the 16S rRNA gene and gyrB gene (DNA gyrase B subunit gene) revealed that strain QC81-06T clustered with Sporolactobacillus species but the strain was clearly distinct from other Sporolactobacillus species with significant bootstrap values. The levels of 16S rRNA gene and gyrB gene sequence similarities between strain QC81-06T and the other strains of the cluster were 96.0–97.0 % and 75.1–77.2 %, respectively. On the basis of these results, strain QC81-06T should be classified as a novel Sporolactobacillus species for which the name Sporolactobacillus putidus is proposed. The type strain is strain QC81-06T (=DSM 21265T=JCM 15325T).
Desulfitobacterium aromaticivorans sp. nov. and Geobacter toluenoxydans sp. nov., iron-reducing bacteria capable of anaerobic degradation of monoaromatic hydrocarbons
Authors: Kunapuli Umakanth , Jahn Michael K. , Lueders Tillmann , Geyer Roland , Heipieper Hermann J. , Meckenstock Rainer U.
Published: November 2009

Dissimilatory iron reduction plays a significant role in subsurface environments. Currently, it is assumed that members of the genusGeobacterconstitute the majority of the iron-reducing micro-organisms that oxidize aromatic compounds in contaminated subsurface environments. Here, we report the isolation of two phylogenetically distinct pure cultures of iron-reducing degraders of monoaromatic hydrocarbons, strain TMJ1T, which belongs to the genusGeobacterwithin theDeltaproteobacteria, and strain UKTLT, belonging to the genusDesulfitobacteriumwithin theClostridia. Both strains utilize a wide range of substrates as carbon and energy sources, including the aromatic compounds toluene, phenol andp-cresol. Additionally, strain UKTLTutilizeso-xylene and TMJ1Tutilizesm-cresol. Anaerobic degradation of toluene in both strains ando-xylene in strain UKTLTis initiated by activation with fumarate addition to the methyl group. The genomic DNA G+C contents of strains TMJ1Tand UKTLTare 54.4 and 47.7 mol%, respectively. Based on a detailed physiological characterization and phylogenetic analysis of the 16S rRNA genes of both strains, we propose the namesDesulfitobacterium aromaticivoranssp. nov. (type strain UKTLT=DSM 19510T=JCM 15765T) andGeobacter toluenoxydanssp. nov. (type strain TMJ1T=DSM 19350T=JCM 15764T) to accommodate these strains. To the best of our knowledge, strain UKTLTis the first described spore-forming, iron-reducing bacterium that can degrade aromatic hydrocarbons.