bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal and mechanical response of PBX 9501 under contact excitation
Authors: Mares J. O. , Miller J. K. , Sharp N. D. , Moore D. S. , Adams D. E. , Groven L. J. , Rhoads J. F. , Son S. F.
Published: February 2013

The thermal and mechanical responses of a cyclotetramethylene-tetranitramine-based explosive (PBX 9501) and two non-energetic mock materials (900-21 and PBS 9501) under high-frequency mechanical excitation are presented. Direct contact ultrasound transducers were used to excite samples through a frequency range of 50 kHz to 40 MHz. The mechanical response of each sample was approximated from a contact receiving transducer and trends were confirmed via laser Doppler vibrometry. The steady-state thermal response of the samples was measured at discrete excitation frequencies via infrared thermography. A maximum temperature rise of approximately 15 K was observed in PBX 9501, and the mock materials exhibited similar thermal characteristics. Temperature gradients were calculated to estimate the total heat generated within the samples due to the mechanical excitation. The active heating mechanisms were found to be highly dependent on the frequency of excitation. Possible mechanisms of heating at frequencies below 1 MHz are likely related to bulk motion. Above this frequency, the active heating mechanisms are likely related to particle-scale processes. The observed phenomena may prove useful in the aid of current trace vapor detection methods for explosives.
Effects of FeCo magnetic nanoparticles on microstructure of Sn-Ag-Cu alloys
Authors: Xu Siyang , Habib Ashfaque H. , Prasitthipayong Anya , McHenry Michael E.
Published: February 2013

Sn-Ag-Cu (SAC) alloys have been regarded as the most promising candidates for lead-free solders in the electronic packaging industry. We prepared SAC solder-FeCo magnetic nanoparticles (MNPs) composite paste with different MNP concentration and used AC magnetic fields localized heating to cause their reflow. Differential scanning calorimetry results show a reduced undercooling of the composite paste with the addition of MNPs. Transmission electron microscope prove that the FeCo MNPs are distributed in Sn matrix of the reflowed solder composites. Optical micrographs show a decrease in the amount of primary Ag3Sn and β-Sn dendrites, and an increase in the amount of eutectic microconstituents with increasing MNPs. The addition of FeCo MNPs is considered to promote the solidification of β-Sn by providing more heterogeneous nucleation sites at a relatively low undercooling, which results in the microstructural refinement in the as-prepared solder joints.
Electric-voltage control of magnetism in Fe/BaTiO3 heterostructured multiferroics
Authors: Venkataiah G. , Wada E. , Taniguchi H. , Itoh M. , Taniyama T.
Published: February 2013

Electric field (E) control of the magnetic anisotropy and coercivity (HC) of a Fe film in Fe/BaTiO3 (BTO) is demonstrated at room temperature in the tetragonal phase of BTO. Polarizing microscopy and x-ray diffraction analysis of BTO (001) surface show distinctly two different regions; one with a1, a2 and c domains separated by 180° and 90° domain boundaries (DBs) (region 1) and the other with a1 domains separated by 180° DBs (region 2). The Fe film on region 1 shows complex magnetic anisotropy with the net magnetic easy axis in between [100] and [110] directions of BTO, while the magnetic anisotropy in region 2 exhibits two fold symmetry with an easy axis along [100]. In applied electric field (±10 kV/cm), the magnetic easy axis of the Fe film in region 1 is switched to the [110] direction of BTO, whereas in region 2 it stays unaffected. The HC versus E curves in region 1 show a butterfly-like behavior, while in region 2 no changes are observed. Also, the HC measured in E = ±10 kV/cm at different magnetic field orientations shows dramatic changes in region 1 compared to region 2. The observed electric field dependent magnetic response in both regions can be understood based on the DBs modifications and associated strain effects.
A neutron spin echo resolved grazing incidence scattering study of crystallites in organic photovoltaic thin films
Authors: Parnell A. J. , Dalgliesh R. M. , Jones R. A. L. , Dunbar A. D. F.
Published: February 2013

Neutron spin echo resolved grazing incidence scattering (SERGIS) was used to probe crystallites of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) produced by extensive thermal annealing of a poly(3-hexylthiophene-2,5-diyl)(P3HT):PCBM organic photovoltaic layer. After annealing a thin film of P3HT:PCBM, PCBM crystallites appear on the sample surface, and a strong SERGIS signal is observed superimposed on the specular reflection. Features in the data can be readily correlated with length scales of the crystallites determined using atomic force microscopy and indicate that in such cases the SERGIS signal may be interpreted as a form of small angle neutron scattering.
Macroscale refrigeration by nanoscale electron transport
Authors: Lowell Peter J. , O'Neil Galen C. , Underwood Jason M. , Ullom Joel N.
Published: February 2013

We demonstrate a general-purpose solid-state refrigerator for sub-Kelvin temperatures based on the tunneling of hot electrons through normal-metal/insulator/superconductor (NIS) junctions. Previous devices using this cooling principle fell short of general-purpose refrigerators since they could not be coupled to arbitrary payloads. To create a viable refrigerator, we developed optimized NIS structures and techniques to couple multiple such structures to arbitrary objects. Using three linked NIS devices, we reduced the temperature of a 1.9 cm3 copper stage from 290 mK to 256 mK with 700 pW of cooling power at 290 mK. We present plans to achieve base temperatures near 100 mK.
Gate voltage induced phase transition in magnetite nanowires
Authors: Gooth Johannes , Zierold Robert , Gluschke Jan G. , Boehnert Tim , Edinger Stefan , Barth Sven , Nielsch Kornelius
Published: February 2013

Since its discovery in 1939 the origin of the phase transition in magnetite (Fe3O4) has been an object of intensive research and great controversy. Here, electrical resistance measurements as a function of gate voltage have been performed on single-crystalline Fe3O4 nanowires, showing that high electric fields trigger the breakdown of the insulating phase into a highly conductive state. Furthermore, the Verwey transition itself is suppressed by the gate voltage.
Direct measurement of force exerted during single microbubble generation
Authors: Deguchi Shinji , Takahashi Satoshi , Hiraki Hidenori , Tanimura Syuhei
Published: February 2013

While there has been progress in the understanding of microbubble mechanics, the force associated with their formation has not previously been measured. Here we directly measure the force exerted during microbubble generation. We illuminate a carbon microfiber immersed in distilled water by using an infrared laser to produce individual bubbles. The fiber is elastically deformable and acts as a force sensor. A force of several nano-Newtons was detected on generation of each bubble. We show that water vaporization is responsible for the primary formation of the bubbles, and their subsequent expansion is caused by the diffusion of dissolved gases.
Negative gate-bias temperature stability of N-doped InGaZnO active-layer thin-film transistors
Authors: Raja Jayapal , Jang Kyungsoo , Balaji Nagarajan , choi Woojin , Thuy Trinh Thanh , Yi Junsin
Published: February 2013

Stability of negative bias temperature stress (NBTS) of nitrogen doped amorphous InGaZnO (a-IGZO) thin-film transistor (TFT) is investigated. Undoped a-IGZO TFT stressed at 333 K exhibit a larger negative ΔVTH (−3.21 V) with an unpredictable sub-threshold swing (SS) of hump shaped transfer curve due to the creation of meta-stable traps. Defects related hump formation has disappeared with small ΔVTH (−1.13 V) and ΔSS (0.018 V/dec) in nitrogen doped a-IGZO TFT. It is observed that nitrogen doping enhances device stability by well controlled oxygen vacancy and trap sites in channel and channel/dielectric interface.
Conjugate feedback induced suppression and generation of oscillations in the Chua circuit: Experiments and simulations
Authors: Mandal Tirtha , Singla Tanu , Rivera M. , Parmananda P.
Published: February 2013

We study the suppression (amplitude death) and generation of oscillations (rhythmogenesis) in the Chua circuit using a feedback term consisting of conjugate variables (conjugate feedback). When the independent Chua circuit (without feedback) is placed in the oscillatory domain, this conjugate feedback induces amplitude death in the system. On the contrary, introducing the conjugate feedback in the system exhibiting fixed point behavior results in the generation of rhythms. Furthermore, it is observed that the dynamics of the Chua circuit could be tuned efficiently by varying the strength of this feedback term. Both experimental and numerical results are presented.
First principles study of magnetic anisotropy and magnetoelectric effect of FePd/MgO(001) ultrathin films
Authors: He K. H. , Chen J. S.
Published: February 2013

The magnetic anisotropy and magnetoelectric effect of FePd/MgO(001) ultrathin films were studied by first principles calculations. The calculation results showed that the magnetization easy axis was in the film normal and the magnetic anisotropy energy (MAE) was reduced with the film thickness. Furthermore, the MAE of FePd reached maximum at the lattice constant of 4.05 Å. The MAE of FePd/MgO films decreased with increasing applied electric field, and the magnitude of the interfacial magnetoelectric coefficient was about 1.4 × 10−12 G cm2/V, which was larger than that in previous reports of Fe/MgO. The calculations also suggested that the MAE was largely dependent on the difference in the orbital moment between [001] and [100] magnetization directions.
Magnetic state and exchange interaction in GdScGe: Ab initio study
Authors: Liu X. B. , Altounian Z. , Han Xianghua , Poudyal Narayan , Ping Liu J.
Published: February 2013

The electronic structure and magnetic properties for GdScGe system have been studied via a first-principles density functional calculation. The energy band structure has been calculated in a generalized gradient approximation, plus Hubbard U approach. For Gd atoms, seven spin-up 4f bands are fully occupied and situated at the bottom of Ge 4s-like states, while the spin-down 4f hole levels are completely unoccupied and well above the Fermi level. The calculated magnetic moment is 7.6 μB per formula unit and is not sensitive to the change of the unit cell volume. The exchange interaction increases with decreasing unit cell volume, which results in a pressure induced enhancement of the Curie temperature (TC). TC increases from about 345 K to 410 K as external pressure increases from 0 to 18 GPa. With the experimental lattice constants, the calculated TC is 353 K, which is in good agreement with the experimental value (TCexp.=349K).
High efficiency, modular, optical pulse shaping technique for tunable terahertz generation from InAs
Authors: Adipa Samuel , Lytle Amy L. , Gagnon Etienne
Published: February 2013

We demonstrate a high energy throughput, modular optical laser pulse shaping technique for generating tunable, narrowband, terahertz radiation from the surface of InAs. We achieve a frequency selectivity (Δf/f) of 0.10 at 1.18 THz and demonstrate an energy throughput of up to 98% using two etalons to create a sequence of optical pulses. In contrast with previously reported schemes, our technique does not rely on interferometry or involve diffractive optical elements, making it robust and relatively inexpensive to implement. This technique can be expanded with additional etalons in order to achieve greater frequency selectivity without sacrificing efficiency.
A full-color reflective display using polymer-stabilized blue phase liquid crystal
Authors: Yan Jin , Wu Shin-Tson , Cheng Kung-Lung , Shiu Jyh-Wen
Published: February 2013

We demonstrate a full-color-capability reflective display using red, green, and blue sub-pixels of polymer-stabilized blue phase liquid crystal (BPLC) with different pitch lengths. Vivid colors originate from three-dimensional BPLC photonic crystalline structure. Surface alignment plays a key role to generate uniform and saturated colors in the voltage-off state. Analogous grayscale is achieved by the electric-field-induced unwinding of double-twist structure. This working principle is drastically different from the phase retardation effect of conventional liquid crystal displays. Moreover, the submillisecond response time enables crisp video displays without image blurring. Potential applications for reflective 3D display are also analyzed.
Atomic layer-by-layer oxidation of Ge (100) and (111) surfaces by plasma post oxidation of Al2O3/Ge structures
Authors: Zhang Rui , Huang Po-Chin , Lin Ju-Chin , Takenaka Mitsuru , Takagi Shinichi
Published: February 2013

The ultrathin GeOx/Ge interfaces formed on Ge (100) and (111) surfaces by applying plasma post oxidation to thin Al2O3/Ge structures are characterized in detail using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy. It is found that the XPS signals assigned to Ge 1+ and the 2+ states in the GeOx layers by post plasma oxidation have oscillating behaviors on Ge (100) surfaces in a period of ∼0.3 nm with an increase in the GeOx thickness. Additionally, the oscillations of the signals assigned to Ge 1+ and 2+ states show opposite phase to each other. The similar oscillation behaviors are also confirmed on Ge (111) surfaces for Ge 1+ and 3+ states in a period of ∼0.5 nm. These phenomena can be strongly regarded as an evidence of the atomic layer-by-layer oxidation of GeOx/Ge interfaces on Ge (100) and (111) surfaces.
Creation of diffraction-limited non-Airy multifocal arrays using a spatially shifted vortex beam
Authors: Lin Han , Gu Min
Published: February 2013

Diffraction-limited non-Airy multifocal arrays are created by focusing a phase-modulated vortex beam through a high numerical-aperture objective. The modulated phase at the back aperture of the objective resulting from the superposition of two concentric phase-modulated vortex beams allows for the generation of a multifocal array of cylindrically polarized non-Airy patterns. Furthermore, we shift the spatial positions of the phase vortices to manipulate the intensity distribution at each focal spot, leading to the creation of a multifocal array of split-ring patterns. Our method is experimentally validated by generating the predicted phase modulation through a spatial light modulator. Consequently, the spatially shifted circularly polarized vortex beam adopted in a dynamic laser direct writing system facilitates the fabrication of a split-ring microstructure array in a polymer material by a single exposure of a femtosecond laser beam.
Bicyclic Guanidinates in Mono- and Di-Valent Metal Complexes, Including Group 1/2 and Group 1/12 Heterometallic Systems
Authors: Coles Martyn P. , Hitchcock Peter B.
Published: February 2013

Complexes containing mono-, di-, and mixed mono-/di-valent metal centres supported by the [hpp]– anion (hppH = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) are reported. Amine elimination from Mn(N{SiMe3}2)2 using the neutral guanidine is a clean route to the heteroleptic compound [Mn(hpp)(N{SiMe3}2)]2. Addition of 18-crown-6 to a solution of the hpp– potassium salt (hppK) enables the first potassium derivative of [hpp]– to be structurally analysed, showing that the crown ether restricts aggregation to afford a monometallic structure. Mixed lithium–magnesium and lithium–zinc compounds of general formula Li2M2(hpp)6 (M = Mg, Zn) have been characterised crystallographically showing the guanidinate anions to be present in two different coordination modes, bridging two- or four-metal centres. Spectroscopic measurements suggest a robust framework that is maintained in solution.
Green-up dates in the Tibetan Plateau have continuously advanced from 1982 to 2011
Authors: Zhang Geli , Zhang Yangjian , Dong Jinwei , Xiao Xiangming
Published: February 2013

As the Earth’s third pole, the Tibetan Plateau has experienced a pronounced warming in the past decades. Recent studies reported that the start of the vegetation growing season (SOS) in the Plateau showed an advancing trend from 1982 to the late 1990s and a delay from the late 1990s to 2006. However, the findings regarding the SOS delay in the later period have been questioned, and the reasons causing the delay remain unknown. Here we explored the alpine vegetation SOS in the Plateau from 1982 to 2011 by integrating three long-term time-series datasets of Normalized Difference Vegetation Index (NDVI): Global Inventory Modeling and Mapping Studies (GIMMS, 1982–2006), SPOT VEGETATION (SPOT-VGT, 1998–2011), and Moderate Resolution Imaging Spectroradiometer (MODIS, 2000–2011). We found GIMMS NDVI in 2001–2006 differed substantially from SPOT-VGT and MODIS NDVIs and may have severe data quality issues in most parts of the western Plateau. By merging GIMMS-based SOSs from 1982 to 2000 with SPOT-VGT–based SOSs from 2001 to 2011 we found the alpine vegetation SOS in the Plateau experienced a continuous advancing trend at a rate of ∼1.04 d·y
−1
from 1982 to 2011, which was consistent with observed warming in springs and winters. The satellite-derived SOSs were proven to be reliable with observed phenology data at 18 sites from 2003 to 2011; however, comparison of their trends was inconclusive due to the limited temporal coverage of the observed data. Longer-term observed data are still needed to validate the phenology trend in the future.
Syllabic discrimination in premature human infants prior to complete formation of cortical layers
Authors: Mahmoudzadeh Mahdi , Dehaene-Lambertz Ghislaine , Fournier Marc , Kongolo Guy , Goudjil Sabrina , Dubois Jessica , Grebe Reinhard , Wallois Fabrice
Published: February 2013

The ontogeny of linguistic functions in the human brain remains elusive. Although some auditory capacities are described before term, whether and how such immature cortical circuits might process speech are unknown. Here we used functional optical imaging to evaluate the cerebral responses to syllables at the earliest age at which cortical responses to external stimuli can be recorded in humans (28- to 32-wk gestational age). At this age, the cortical organization in layers is not completed. Many neurons are still located in the subplate and in the process of migrating to their final location. Nevertheless, we observed several points of similarity with the adult linguistic network. First, whereas syllables elicited larger right than left responses, the posterior temporal region escaped this general pattern, showing faster and more sustained responses over the left than over the right hemisphere. Second, discrimination responses to a change of phoneme (ba vs. ga) and a change of human voice (male vs. female) were already present and involved inferior frontal areas, even in the youngest infants (29-wk gestational age). Third, whereas both types of changes elicited responses in the right frontal region, the left frontal region only reacted to a change of phoneme. These results demonstrate a sophisticated organization of perisylvian areas at the very onset of cortical circuitry, 3 mo before term. They emphasize the influence of innate factors on regions involved in linguistic processing and social communication in humans.
Forces shaping a Hox morphogenetic gene network
Authors: Sotillos Sol , Aguilar Mario , Castelli-Gair Hombría James
Published: February 2013

The Abdominal-B selector protein induces organogenesis of the posterior spiracles by coordinating an organ-specific gene network. The complexity of this network begs the questions of how it originated and what selective pressures drove its formation. Given that the network likely formed in a piecemeal fashion, with elements recruited sequentially, we studied the consequences of expressing individual effectors of this network in naive epithelial cells. We found that, with exception of the Crossveinless-c (Cv-c) Rho GTPase-activating protein, most effectors exert little morphogenetic effect by themselves. In contrast, Cv-c expression causes cell motility and down-regulates epithelial polarity and cell adhesion proteins. These effects differ in cells endogenously expressing Cv-c, which have acquired compensatory mechanisms. In spiracle cells, the down-regulation of polarity and E-cadherin expression caused by Cv-c–induced Rho1 inactivation are compensated for by the simultaneous spiracle up-regulation of guanine nucleotide exchange factor (GEF) proteins, cell polarity, and adhesion molecules. Other epithelial cells that have coopted Cv-c to their morphogenetic gene networks are also resistant to Cv-c’s deleterious effects. We propose that cooption of a novel morphogenetic regulator to a selector cascade causes cellular instability, resulting in strong selective pressure that leads that same cascade to recruit molecules that compensate it. This experimental-based hypothesis proposes how the frequently observed complex organogenetic gene networks are put together.
Spatial extent of an outbreak in animal epidemics
Authors: Dumonteil Eric , Majumdar Satya N. , Rosso Alberto , Zoia Andrea
Published: February 2013

Characterizing the spatial extent of epidemics at the outbreak stage is key to controlling the evolution of the disease. At the outbreak, the number of infected individuals is typically small, and therefore, fluctuations around their average are important: then, it is commonly assumed that the susceptible–infected–recovered mechanism can be described by a stochastic birth–death process of Galton–Watson type. The displacements of the infected individuals can be modeled by resorting to Brownian motion, which is applicable when long-range movements and complex network interactions can be safely neglected, like in the case of animal epidemics. In this context, the spatial extent of an epidemic can be assessed by computing the convex hull enclosing the infected individuals at a given time. We derive the exact evolution equations for the mean perimeter and the mean area of the convex hull, and we compare them with Monte Carlo simulations.
Recruitment of oriens-lacunosum-moleculare interneurons during hippocampal ripples
Authors: Pangalos Maria , Donoso José R. , Winterer Jochen , Zivkovic Aleksandar R. , Kempter Richard , Maier Nikolaus , Schmitz Dietmar
Published: February 2013

Sharp wave-associated ∼200-Hz ripple oscillations in the hippocampus have been implicated in the consolidation of memories. However, knowledge on mechanisms underlying ripples is still scarce, in particular with respect to synaptic involvement of specific cell types. Here, we used cell-attached and whole-cell recordings in vitro to study activity of pyramidal cells and oriens-lacunosum-moleculare (O-LM) interneurons during ripples. O-LM cells received ripple-associated synaptic input that arrived delayed (3.3 ± 0.3 ms) with respect to the maximum amplitude of field ripples and was locked to the ascending phase of field oscillations (mean phase: 209 ± 6°). In line, O-LM cells episodically discharged late during ripples (∼6.5 ms after the ripple maximum), and firing was phase-locked to field oscillations (mean phase: 219 ± 9°). Our data unveil recruitment of O-LM neurons during ripples, suggesting a previously uncharacterized role of this cell type during sharp wave-associated activity.
Model-free forecasting outperforms the correct mechanistic model for simulated and experimental data
Authors: Perretti Charles T. , Munch Stephan B. , Sugihara George
Published: February 2013

Accurate predictions of species abundance remain one of the most vexing challenges in ecology. This observation is perhaps unsurprising, because population dynamics are often strongly forced and highly nonlinear. Recently, however, numerous statistical techniques have been proposed for fitting highly parameterized mechanistic models to complex time series, potentially providing the machinery necessary for generating useful predictions. Alternatively, there is a wide variety of comparatively simple model-free forecasting methods that could be used to predict abundance. Here we pose a rather conservative challenge and ask whether a correctly specified mechanistic model, fit with commonly used statistical techniques, can provide better forecasts than simple model-free methods for ecological systems with noisy nonlinear dynamics. Using four different control models and seven experimental time series of flour beetles, we found that Markov chain Monte Carlo procedures for fitting mechanistic models often converged on best-fit parameterizations far different from the known parameters. As a result, the correctly specified models provided inaccurate forecasts and incorrect inferences. In contrast, a model-free method based on state-space reconstruction gave the most accurate short-term forecasts, even while using only a single time series from the multivariate system. Considering the recent push for ecosystem-based management and the increasing call for ecological predictions, our results suggest that a flexible model-free approach may be the most promising way forward.
Folding and ligand recognition of the TPP riboswitch aptamer at single-molecule resolution
Authors: Haller Andrea , Altman Roger B. , Soulière Marie F. , Blanchard Scott C. , Micura Ronald
Published: February 2013

Thiamine pyrophosphate (TPP)-sensitive mRNA domains are the most prevalent riboswitches known. Despite intensive investigation, the complex ligand recognition and concomitant folding processes in the TPP riboswitch that culminate in the regulation of gene expression remain elusive. Here, we used single-molecule fluorescence resonance energy transfer imaging to probe the folding landscape of the TPP aptamer domain in the absence and presence of magnesium and TPP. To do so, distinct labeling patterns were used to sense the dynamics of the switch helix (P1) and the two sensor arms (P2/P3 and P4/P5) of the aptamer domain. The latter structural elements make interdomain tertiary contacts (L5/P3) that span a region immediately adjacent to the ligand-binding site. In each instance, conformational dynamics of the TPP riboswitch were influenced by ligand binding. The P1 switch helix, formed by the 5′ and 3′ ends of the aptamer domain, adopts a predominantly folded structure in the presence of Mg
2+
alone. However, even at saturating concentrations of Mg
2+
and TPP, the P1 helix, as well as distal regions surrounding the TPP-binding site, exhibit an unexpected degree of residual dynamics and disperse kinetic behaviors. Such plasticity results in a persistent exchange of the P3/P5 forearms between open and closed configurations that is likely to facilitate entry and exit of the TPP ligand. Correspondingly, we posit that such features of the TPP aptamer domain contribute directly to the mechanism of riboswitch-mediated translational regulation.
KCNJ2
mutation in short QT syndrome 3 results in atrial fibrillation and ventricular proarrhythmia
Authors: Deo Makarand , Ruan Yanfei , Pandit Sandeep V. , Shah Kushal , Berenfeld Omer , Blaufox Andrew , Cerrone Marina , Noujaim Sami F. , Denegri Marco , Jalife José , Priori Silvia G.
Published: February 2013

We describe a mutation (E299V) in
KCNJ2
, the gene that encodes the strong inward rectifier K
+
channel protein (Kir2.1), in an 11-y-old boy. The unique short QT syndrome type-3 phenotype is associated with an extremely abbreviated QT interval (200 ms) on ECG and paroxysmal atrial fibrillation. Genetic screening identified an A896T substitution in a highly conserved region of
KCNJ2
that resulted in a de novo mutation E299V. Whole-cell patch-clamp experiments showed that E299V presents an abnormally large outward I
K1
at potentials above −55 mV (
P
< 0.001 versus wild type) due to a lack of inward rectification. Coexpression of wild-type and mutant channels to mimic the heterozygous condition still resulted in a large outward current. Coimmunoprecipitation and kinetic analysis showed that E299V and wild-type isoforms may heteromerize and that their interaction impairs function. The homomeric assembly of E299V mutant proteins actually results in gain of function. Computer simulations of ventricular excitation and propagation using both the homozygous and heterozygous conditions at three different levels of integration (single cell, 2D, and 3D) accurately reproduced the electrocardiographic phenotype of the proband, including an exceedingly short QT interval with merging of the QRS and the T wave, absence of ST segment, and peaked T waves. Numerical experiments predict that, in addition to the short QT interval, absence of inward rectification in the E299V mutation should result in atrial fibrillation. In addition, as predicted by simulations using a geometrically accurate three-dimensional ventricular model that included the His–Purkinje network, a slight reduction in ventricular excitability via 20% reduction of the sodium current should increase vulnerability to life-threatening ventricular tachyarrhythmia.
Hypothalamic ventromedial COUP-TFII protects against hypoglycemia-associated autonomic failure
Authors: Sabra-Makke Lina , Maritan Micol , Planchais Julien , Boutant Marie , Pégorier Jean-Paul , Even Patrick C. , Vasseur-Cognet Mireille , Bossard Pascale
Published: February 2013

The nuclear receptor Chicken Ovalbumin Upstream Promoter–Transcription Factor II (COUP-TFII) is an important coordinator of glucose homeostasis through its function in different organs such as the endocrine pancreas, adipose tissue, skeletal muscle, and liver. Recently we have demonstrated that COUP-TFII expression in the hypothalamus is restricted to a subpopulation of neurons expressing the steroidogenic factor 1 transcription factor, known to play a crucial role in glucose homeostasis. To understand the functional significance of COUP-TFII expression in the steroidogenic factor 1 neurons, we generated hypothalamic ventromedial nucleus-specific COUP-TFII KO mice using the cyclization recombination/locus of X-overP1 technology. The heterozygous mutant mice display insulin hypersensitivity and a leaner phenotype associated with increased energy expenditure and similar food intake. These mutant mice also present a defective counterregulation to hypoglycemia with altered glucagon secretion. Moreover, the mutant mice are more likely to develop hypoglycemia-associated autonomic failure in response to recurrent hypoglycemic or glucopenic events. Therefore, COUP-TFII expression levels in the ventromedial nucleus are keys in the ability to resist the onset of hypoglycemia-associated autonomic failure.
Direct involvement of DprA, the transformation-dedicated RecA loader, in the shut-off of pneumococcal competence
Authors: Mirouze Nicolas , Bergé Mathieu A. , Soulet Anne-Lise , Mortier-Barrière Isabelle , Quentin Yves , Fichant Gwennaele , Granadel Chantal , Noirot-Gros Marie-Françoise , Noirot Philippe , Polard Patrice , Martin Bernard , Claverys Jean-Pierre
Published: February 2013

Significance

This article concerns the control of competence for bacterial genetic transformation. Competence is transient in the human pathogen
Streptococcus pneumoniae
, involving the specific expression of ∼100 genes that are turned ON suddenly and OFF almost as abruptly. Although the mechanism rendering all cells in a culture simultaneously competent is well understood, how competence stops has remained unknown. Here, we unravel the mechanism of shut-off, describing the discovery that a key recombination protein, DprA, exerts a negative control on competence through direct, physical interaction with the master regulator of competence, the response regulator ComE, to abolish transcription from ComE-activated promoters.
Onchocerca volvulus
-neurotransmitter tyramine is a biomarker for river blindness
Authors: Globisch Daniel , Moreno Amira Y. , Hixon Mark S. , Nunes Ashlee A. K. , Denery Judith R. , Specht Sabine , Hoerauf Achim , Janda Kim D.
Published: February 2013

Onchocerciasis, also known as “river blindness”, is a neglected tropical disease infecting millions of people mainly in Africa and the Middle East but also in South America and Central America. Disease infectivity initiates from the filarial parasitic nematode
Onchocerca volvulus
, which is transmitted by the blackfly vector
Simulium
sp. carrying infectious third-stage larvae. Ivermectin has controlled transmission of microfilariae, with an African Program elimination target date of 2025. However, there is currently no point-of-care diagnostic that can distinguish the burden of infection—including active and/or past infection—and enable the elimination program to be effectively monitored. Here, we describe how liquid chromatography-MS–based urine metabolome analysis can be exploited for the identification of a unique biomarker,
N
-acetyltyramine-
O
,β-glucuronide (NATOG), a neurotransmitter-derived secretion metabolite from
O. volvulus
. The regulation of this tyramine neurotransmitter was found to be linked to patient disease infection, including the controversial antibiotic doxycycline treatment that has been shown to both sterilize and kill adult female worms. Further clues to its regulation have been elucidated through biosynthetic pathway determination within the nematode and its human host. Our results demonstrate that NATOG tracks
O. volvulus
metabolism in both worms and humans, and thus can be considered a host-specific biomarker for onchocerciasis progression. Liquid chromatography-MS–based urine metabolome analysis discovery of NATOG not only has broad implications for a noninvasive host-specific onchocerciasis diagnostic but provides a basis for the metabolome mining of other neglected tropical diseases for the discovery of distinct biomarkers and monitoring of disease progression.
Stereochemical evidence for stabilization of a nitrogen cation by neighboring chlorine or bromine
Authors: Ohwada Tomohiko , Tani Norihiko , Sakamaki Yuko , Kabasawa Yoji , Otani Yuko , Kawahata Masatoshi , Yamaguchi Kentaro
Published: February 2013

Neighboring group participation is one of the fundamental interactions in organic reactions and can influence the reaction rate, stereoselectivity, and reaction pathway through transient carbon-carbon or carbon-heteroatom bond formation. The latter category includes cyclic three- and five-membered bromonium ions, wherein lone-pair electrons of the monovalent bromine atom stabilize a trigonal carbocation. Although similar nucleophilic interactions of monovalent halogen atoms with non–carbon atom-centered cations have long been predicted, we know of no experimental evidence of such an interaction. Here, we demonstrate a nucleophilic interaction of neighboring monovalent halogen to stabilize an imino sp
2
nitrogen cation. This interaction has an overwhelming impact on the reaction pathway, completely altering the migratory preference under acid-catalyzed Beckmann rearrangement conditions. In sharp contrast to the general case of
anti
-migration,
peri
-chloro– and
peri
-bromo–substituted O-tosyl oximes of 1-tetralone substructures and their derivatives undergo
syn
-migration under Beckmann rearrangement conditions (i.e., migration of the group on the
syn
side of the leaving group). The
peri
-chloro or
peri
-bromo neighboring group turned out to provide strong anchimeric assistance for
syn
-migration via transient formation of a cyclic five-membered imino-halonium cation with dissociation of tosylic acid. Thus, formation of the
syn
-migration products can be attributed to a reaction mechanism that is different from the conventional Beckmann rearrangement mechanism. That is, the positively charged imino nitrogen atom can be stabilized by, or interact with, a chloro or bromo group in close spatial proximity, and this interaction dramatically changes the reaction pathway, selectively affording regioisomeric lactams from closely related starting materials.
A study of the dynamics of sex differences in adulthood
Authors: Trofimova Irina
Published: February 2013

Studies of gender differences using primarily young individuals show that males, on average, perform better than females in physical activities but worse than females on tests of verbal abilities. There is however a controversy about the existence of these sex differences in adulthood. Our study used 1271 participants from four cultural backgrounds (Chinese, multi‐generation Canadians, Indu‐Canadians, and European‐Canadians) divided in five age groups. We measured sex differences in the time required for participants to complete a lexical task experiment, and also assessed their verbal tempo and physical endurance using a validated temperament test (Structure of Temperament Questionnaire). We found a significant female advantage in time on the lexical task and on the temperament scale of social–verbal tempo, and a male advantage on the temperament scale of physical endurance. These sex differences, however, were more pronounced in young age groups (17–24), fading in older groups. This “middle age–middle sex” phenomenon suggests that sex differences in these two types of abilities observed in younger groups might be “a matter of age,” and should not be attributed to gender in general. A one‐dimensional approach to sex differences (common in meta‐analytic studies) therefore overlooks a possible interaction of sex differences with age.
The relationship between cognitive errors, coping strategies, and clients' experiences in session: An exploratory study
Authors: Antunes-Alves Sara , Thompson Katherine , Kramer Ueli , Drapeau Martin
Published: February 2013

Aim: Cognitive errors (CE) and coping strategies (CS) can bear weight on how individuals relate to others and perceive interpersonal relationships. However, there is little research into how clients' erroneous beliefs and maladaptive coping strategies can interfere with the therapeutic process. This study utilised a sample of healthy clients to explore the relationship between their CEs and CSs and their evaluation of therapy. Method: Therapy sessions of undergraduate student clients (N =26) were rated using the Cognitive Error Rating Scale (CERS – 3rd edition), the Coping Patterns Rating Scale (CPRS;), the Session Evaluation Questionnaire (SEQ) and the Session Impact Scale (SIS). Results: Clients who engaged in dichotomous thinking endorsed problem solving less and were more likely to feel unsupported and misunderstood by the therapist. Clients who discounted the positive tended to feel more pressured and judged by therapists. Conversely, those who engaged in problem solving were more likely to find sessions deeper and more valuable as compared to those who reacted to stressful events by submission, escape, or opposition. Implications: Better understanding how and when a client's cognitive errors and coping mechanisms are at play during therapy can help clinicians to address them and intervene appropriately.
Comparison of Traditional and Fermented Soybean Meals as Alternatives to Fish Meal in Hybrid Striped Bass Feeds
Authors: Rombenso Artur , Crouse Curtis , Trushenski Jesse
Published: February 2013

Soybean meal is one of the most common fish meal alternatives used in aquafeeds because of its high protein density, favorable amino acid profile, comparatively low price, and widespread availability. However, palatability issues and antinutritional factors limit soybean meal inclusion, particularly in feeds for carnivorous fishes. Various processing strategies, including fermentation, may offer some advantage in terms of reducing or eliminating antinutritional factors while enhancing protein content, improving protein absorption rate, and feed intake. Accordingly, we assessed production performance of juvenile hybrid Striped Bass (White Bass Morone chrysops × Striped Bass M. saxatilis) fed diets containing 30% menhaden fish meal, or reduced or fish-meal-free feeds (0, 5, or 10% fish meal) containing traditional soybean meal (47.5% crude protein) or PepSoyGen fermented soybean meal (52.0% crude protein) as the principal sources of dietary protein. Each dietary treatment was fed to quadruplicate tanks of fish (10 fish/tank; average individual weight = 18.1 ± 0.2 g [mean ± SE], n = 4) in a recirculation system for 8 weeks. Production performance tended to decline among fish fed diets containing less than 10% fish meal; however, this effect was less overt among those fed the fermented soybean meal-based feeds. At each level of fish meal replacement, fish fed the fermented soybean meal treatment outgrew those fed the corresponding traditional soybean meal feed, though differences at the 5% fish meal level were not statistically significant. Fermentation appears to increase the acceptability and biological value of soybean meal in hybrid Striped Bass feeds, and PepSoyGen shows promise as a fish meal alternative for aquafeeds for carnivorous fishes.
Both endonucleolytic and exonucleolytic cleavage mediate ITS1 removal during human ribosomal RNA processing
Authors: Sloan Katherine E. , Mattijssen Sandy , Lebaron Simon , Tollervey David , Pruijn Ger J.M. , Watkins Nicholas J.
Published: February 2013

Human ribosome production is up-regulated during tumorogenesis and is defective in many genetic diseases (ribosomopathies). We have undertaken a detailed analysis of human precursor ribosomal RNA (pre-rRNA) processing because surprisingly little is known about this important pathway. Processing in internal transcribed spacer 1 (ITS1) is a key step that separates the rRNA components of the large and small ribosomal subunits. We report that this was initiated by endonuclease cleavage, which required large subunit biogenesis factors. This was followed by 3′ to 5′ exonucleolytic processing by RRP6 and the exosome, an enzyme complex not previously linked to ITS1 removal. In contrast, RNA interference–mediated knockdown of the endoribonuclease MRP did not result in a clear defect in ITS1 processing. Despite the apparently high evolutionary conservation of the pre-rRNA processing pathway and ribosome synthesis factors, each of these features of human ITS1 processing is distinct from those in budding yeast. These results also provide significant insight into the links between ribosomopathies and ribosome production in human cells.
Arp2/3 complex ATP hydrolysis promotes lamellipodial actin network disassembly but is dispensable for assembly
Authors: Ingerman Elena , Hsiao Jennifer Ying , Mullins R. Dyche
Published: February 2013

We examined the role of ATP hydrolysis by the Arp2/3 complex in building the leading edge of a cell by studying the effects of hydrolysis defects on the behavior of the complex in the lamellipodial actin network of Drosophila S2 cells and in a reconstituted, in vitro, actin-based motility system. In S2 cells, nonhydrolyzing Arp2 and Arp3 subunits expanded and delayed disassembly of lamellipodial actin networks and the effect of mutant subunits was additive. Arp2 and Arp3 ATP hydrolysis mutants remained in lamellipodial networks longer and traveled greater distances from the plasma membrane, even in networks still containing wild-type Arp2/3 complex. In vitro, wild-type and ATP hydrolysis mutant Arp2/3 complexes each nucleated actin and built similar dendritic networks. However, networks constructed with Arp2/3 hydrolysis-defective mutants were more resistant to disassembly by cofilin. Our results indicate that ATP hydrolysis on both Arp2 and Arp3 contributes to dissociation of the complex from the actin network but is not strictly necessary for lamellipodial network disassembly.
Visualizing Samsonfish (Seriola hippos) with a Reson 7125 Seabat multibeam sonar
Authors: Parsons Miles J. G. , Parnum Iain M. , McCauley Robert D.
Published: February 2013

Parsons, M. J. G., Parnum, I. M., and McCauley, R. D. 2013. Visualizing Samsonfish (Seriola hippos) with a Reson 7125 Seabat multibeam sonar – ICES Journal of Marine Science, 70: 665–674. In Western Australia, aggregations of Samsonfish (Seriola hippos) form each summer to spawn in waters west of Rottnest Island. In this study, a Reson 7125 Seabat multibeam sonar (400 kHz) was pole mounted aboard a 21.6 m vessel, conducting acoustic transects to acquire acoustic backscatter simultaneously from a midwater aggregation of S. hippos and the wreck it surrounded. The processed backscatter produced high-resolution visualizations of both the fish and seabed. During a 15 min period, the centroid of the aggregation moved 91 m around the eastern and northeastern side of the wreck and probably exhibited lateral vessel avoidance behaviour from the survey vessel. Additionally, a northeasterly current at the site was inferred from subtle habitat features, suggesting that at the time of the survey the aggregation preferred to remain upcurrent of the wreck. These findings confirmed that the S. hippos aggregations do not necessarily remain directly above the wrecks and do not always remain sedentary. Aggregation acoustic density packing at the survey site was observed at 12.7 ± 2.4 m3 per fish, equivalent to ∼1.6 ± 0.1 body lengths nearest-neighbour distance.
Hard White Versus Hard Red Wheats: Taste Tests and Milling and Baking Properties
Authors: Talbert Luther E. , Hofer Petrea , Nash Deanna , Martin John M. , Lanning Susan P. , Sherman Jamie D. , Giroux Michael J.
Published: February 2013

Molecular markers for the red grain color (R) loci controlling seed color and the polyphenol oxidase (Ppo‐A1) locus controlling polyphenol oxidase (PPO) activity in seed have recently been developed. These markers provided the opportunity to convert the hard red spring wheat cultivars Choteau and Hank to white‐seeded versions with high and low PPO levels, respectively. These sets of near‐isogenic lines provided material to test the effects of seed color and PPO activity on a range of end‐use quality traits. We tested recurrent parents Choteau and Hank, along with near‐isogenic derivatives with white seed, in two replicated trials in Bozeman, Montana, for end‐use quality parameters. The white‐seeded lines consisted of both high‐ and low‐PPO near‐isogenic lines. The primary impact of white seed was the production of whole wheat bread with a perceived sweeter taste relative to the red‐seeded lines. Noodle color was not consistently impacted by the level of PPO variation despite relatively large reductions in PPO level. The alleles for white seed color did not appear to impact agronomic traits. These results suggested that hard white low‐PPO hard spring wheat would be advantageous in terms of conferring brighter color to Asian noodles and a sweeter taste to whole wheat bread.
Host-Induced Gene Silencing in Barley Powdery Mildew Reveals a Class of Ribonuclease-Like Effectors
Authors: Pliego Clara , Nowara Daniela , Bonciani Giulia , Gheorghe Dana M. , Xu Ruo , Surana Priyanka , Whigham Ehren , Nettleton Dan , Bogdanove Adam J. , Wise Roger P. , Schweizer Patrick , Bindschedler Laurence V. , Spanu Pietro D.
Published: February 2013

Obligate biotrophic pathogens of plants must circumvent or counteract defenses to guarantee accommodation inside the host. To do so, they secrete a variety of effectors that regulate host immunity and facilitate the establishment of pathogen feeding structures called haustoria. The barley powdery mildew fungus Blumeria graminis f. sp. hordei produces a large number of proteins predicted to be secreted from haustoria. Fifty of these Blumeria effector candidates (BEC) were screened by host-induced gene silencing (HIGS), and eight were identified that contribute to infection. One shows similarity to β-1,3 glucosyltransferases, one to metallo-proteases, and two to microbial secreted ribonucleases; the remainder have no similarity to proteins of known function. Transcript abundance of all eight BEC increases dramatically in the early stages of infection and establishment of haustoria, consistent with a role in that process. Complementation analysis using silencing-insensitive synthetic cDNAs demonstrated that the ribonuclease-like BEC 1011 and 1054 are bona fide effectors that function within the plant cell. BEC1011 specifically interferes with pathogen-induced host cell death. Both are part of a gene superfamily unique to the powdery mildew fungi. Structural modeling was consistent, with BEC1054 adopting a ribonuclease-like fold, a scaffold not previously associated with effector function.