bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime
Authors: Hu H. , Koochesfahani M. M.
Published: October 2011

The thermal effects on the wake flow behind a heated circular cylinder operating in the mixed convection regime were investigated experimentally in the present study. The experiments were conducted in a vertical water channel with the heated cylinder placed horizontally and the flow approaching the cylinder downwards. With such a flow arrangement, the direction of the thermally induced buoyancy force acting on the fluid surrounding the heated cylinder would be opposite to the approach flow. During the experiments, the temperature and Reynolds number of the approach flow were held constant. By adjusting the surface temperature of the heated cylinder, the corresponding Richardson number ($\mathit{Ri}= \mathit{Gr}/ {\mathit{Re}}^{2} $) was varied between 0.0 (unheated) and 1.04, resulting in a change in the heat transfer process from forced convection to mixed convection. A novel flow diagnostic technique, molecular tagging velocimetry and thermometry (MTV&T), was used for qualitative flow visualization of thermally induced flow structures and quantitative, simultaneous measurements of flow velocity and temperature distributions in the wake of the heated cylinder. With increasing temperature of the heated cylinder (i.e. Richardson number), significant modifications of the wake flow pattern and wake vortex shedding process were clearly revealed. When the Richardson number was relatively small ($\mathit{Ri}\leq 0. 31$), the vortex shedding process in the wake of the heated cylinder was found to be quite similar to that of an unheated cylinder. As the Richardson number increased to${\ensuremath{\sim} }0. 50$, the wake vortex shedding process was found to be ‘delayed’, with the wake vortex structures beginning to shed much further downstream. As the Richardson number approached unity ($\mathit{Ri}\geq 0. 72$), instead of having ‘Kármán’ vortices shedding alternately at the two sides of the heated cylinder, concurrent shedding of smaller vortex structures was observed in the near wake of the heated cylinder. The smaller vortex structures were found to behave more like ‘Kelvin–Helmholtz’ vortices than ‘Kármán’ vortices, and adjacent small vortices would merge to form larger vortex structures further downstream. It was also found that the shedding frequency of the wake vortex structures decreased with increasing Richardson number. The wake closure length and the drag coefficient of the heated cylinder were found initially to decrease slightly when the Richardson number was relatively small ($\mathit{Ri}\lt 0. 31$), and then to increase monotonically with increasing Richardson number as the Richardson number became relatively large ($\mathit{Ri}\gt 0. 31$). The average Nusselt number ($ \overline{\mathit{Nu}} $) of the heated cylinder was found to decrease almost linearly with increasing Richardson number.
Posterior glottic gap and age as factors predicting voice outcome of injection laryngoplasty in patients with unilateral vocal fold paralysis
Authors: Choi J , Son Y-I , So Y K , Byun H , Lee E-K , Yun Y-S
Published: October 2011

Objectives:

This study aimed to analyse demographic profiles and pre-injection stroboscopic findings for patients with unilateral vocal fold paralysis, to investigate possible predictive factors for voice outcomes of injection laryngoplasty.

Materials and methods:

Fifty-nine unilateral vocal fold paralysis patients underwent vocal fold augmentation, using transcutaneous Artecoll (polymethyl methacrylate microspheres plus bovine collagen) injection into the paralysed vocal fold via the cricothyroid space. Three months later, patients were divided into improved (n = 44) and unimproved (n = 15) groups, using the perceptual grade-roughness-breathiness-asthenia-strain scale, and their clinical characteristics and pre-operative stroboscopic findings compared.

Results:

The improved group were significantly younger than the unimproved group (p = 0.000). The size of the posterior gap on phonation was closely associated with the outcome of injection laryngoplasty (p = 0.015).

Conclusion:

Younger patients with a smaller posterior glottic gap on phonation can be expected to have a more favourable outcome following injection laryngoplasty for correction of glottic insufficiency due to unilateral vocal fold paralysis.
Bacterial meningitis secondary to stapes footplate malformation in a child with an auditory brainstem implant
Authors: Mandalà M , Colletti L
Published: October 2011

Objective:

We report a rare presentation of otogenic bacterial meningitis secondary to a stapes footplate malformation in a paediatric patient with an auditory brainstem implant.

Case report:

A patient with Mondini's dysplasia developed meningitis six years after auditory brainstem implantation. The aetiology was believed to be otogenic, secondary to stapes footplate malformation.

Conclusion:

To our best knowledge, this is the first report of otogenic bacterial meningitis secondary to stapes footplate malformation in a paediatric patient with an auditory brainstem implant. Subjects with inner ear malformations, especially Mondini's dysplasia, need to be carefully evaluated pre-operatively to reduce or eliminate any anatomical conditions which may predispose to meningitis. In children with an auditory brainstem implant and suspected ear malformation, we recommend pre-operative radiological investigation to look for the ‘bulging oval window’ sign. When radiological signs are positive, bilateral exploratory tympanotomy should be performed to detect any undiagnosed anatomical stapes footplate defects, which may predispose to bacterial meningitis.
Advantages of the two-step embryo transfer strategy in human IVF/ICSI cycles
Authors: Yazbeck Chadi , Jamaa Nadia Ben , Hazout André , Cohen-Bacrie Paul , Junca Anne-Marie , Rougier Nathalie
Published: October 2011

The aim of this study was to evaluate the advantages of the two-step embryo transfer (ET) strategy combining a day 2/3 ET with a day 5/6 blastocyst transfer. In an observational comparative study, 400 infertile women were enrolled from two assisted reproductive technology (ART) units according to inclusion criteria: age below 42 years and at least three embryos obtained on day 2 thus allowing an extended in vitro culture. Two groups were defined according to the ET strategy adopted: group 1 had a two-step ET; and group 2 had a day 2/3 ET with (subgroup 2a) or without (subgroup 2b) blastocysts cryopreserved on day 5/6. Live birth rate was significantly higher in group 1 than in subgroups 2a and 2b (36.5% versus 29.4% and 13.4%, respectively; p < 10−3). Multiple pregnancy rates were comparable between groups. After adjusting on major prognostic factors, the two-step ET strategy was still associated with a significantly higher live birth rate than the day 2/3 ET (OR = 2.23; 95% CI: 1.32–3.77). The two-step ET provides better live birth rates than the cleavage-stage ET. It does not increase multiple pregnancy rates if the number of embryos transferred is limited. It also prevents cycle loss when embryos fail to develop into blastocysts.
Treatment of Selective Eating and Dysphagia Using Pre-Chaining and Food Chaining© Therapy Programs
Authors: Fraker Cheri , Walbert Laura
Published: October 2011

Pre-Chaining and Food Chaining© are child-specific intervention programs used to treat pediatric patients with dysphagia and selective eating. Pre-Chaining programs are designed primarily for infants with severe dysphagia. The focus of treatment is rehabilitation of the swallow and pro-active care to keep the infant's feeding development on track as much as possible through the critical periods of the first year of life. At each stage of development, the infant nervous system is ready to acquire new motor skills. The medically fragile infant may not have adequate feeding exposure during these periods of development. This lack of experience may result in great difficulty mastering the skills later in life. Pre-Chaining helps the infant with dysphagia acquire skills with very minimal amounts of food and liquid. Volume is increased only as swallow function and oral skills improve. Food Chaining© has been developed as a systematic method for the treatment of children with food selectivity and aversive eating behaviors. Food Chaining is an individualized, multidisciplinary, home-based feeding program designed to expand food repertoire by emphasizing similar features between accepted and targeted food items. This paper will discuss Pre-Chaining and Food Chaining therapy as methods to treat dysphagia and aversive feeding disorders.
SOS Approach to Feeding
Authors: Toomey Kay A. , Ross Erin Sundseth
Published: October 2011

The Sequential Oral Sensory Approach to Feeding (The SOS Approach) is a transdisciplinary program designed to assess and address the reasons why a child is struggling to eat. Assessment occurs across seven different areas of human function involved in the process of learning to eat: organs, muscles, sensory, learning, development, nutrition, and environment. The SOS Approach uses a whole child perspective, integrating sensory, motor, oral-motor, behavioral/learning, medical, and nutritional factors for both assessment and intervention, resulting in strategies to comprehensively evaluate and manage children with feeding/growth problems. Success is determined by (a) intrinsically motivated and sustained interest in trying new foods, (b) enjoyment in and appropriate skills for eating and drinking a wide range of age-appropriate foods and fluids; (c) consumption of sufficient calories for optimal growth along a child's own percentile line on a growth curve, and (d) improved family understanding and functioning during mealtimes for the development of healthy relationships with food and each other.
Natural media with negative index of refraction: Perspectives of complex transition metal oxides (Review Article)
Authors: Fertman E. L. , Beznosov A. B.
Published: October 2011

The capabilities of perovskite-like compounds with the effect of colossal magnetoresistance (CMR) and some other complex oxides to have a negative index of refraction (NIR) are considered. Physical properties of these compounds are also analyzed from the standpoint of designing tunable metamaterials on their base. Of particular interest are temperature and magnetic field driven first-order transformations in oxides with perovskite structure and in spinels. These transformations give rise to nanophase separated states, using which the properties of negative refraction can be affected. The magnetic-field controlled metamaterials with CMR oxides as a boundary NIR media for a photonic crystal are discussed.
Quartz tuning-fork oscillations in He II and drag coefficient
Authors: Gritsenko I. A. , Zadorozhko A. A. , Neoneta A. S. , Chagovets V. K. , Sheshin G. A.
Published: October 2011

The temperature dependencies of drag coefficient for quartz tuning forks of various geometric dimensions, immersed in the He II, were determined experimentally in the temperature range 0.1–3 K. It is identified, that these dependencies are similar, but the values of drag coefficient are different for tuning forks with different geometric dimensions. It is shown, that the obtained specific drag coefficient depends only on the temperature and frequency of vibrations, when the value of drag coefficient is normalized to the surface area of moving tuning-fork prong. The temperature dependencies of normalized drag coefficient for the tuning forks of various dimensions, wire, and microsphere, oscillating in the Не II, are compared. It is shown, that in the ballistic regime of scattering of quasiparticles, these dependencies are identical and have a slope proportional to T4, which is determined by the density of thermal excitations. In the hydrodynamic regime at T > 0.5 K, the behavior of the temperature dependence of specific drag coefficient is affected by the size and frequency of vibrating body. The empirical relation, which allows to describe the behavior of specific drag coefficient for vibrating tuning forks, microsphere, and wire everywhere over the temperature region and at various frequencies, is proposed.
Green’s function method to the ground state properties of a two-component Bose–Einstein condensate
Authors: Liang Chen , Wei Kong , Ye B. J. , Wen H. M. , Zhou X. Y. , Han R. D.
Published: October 2011

The elementary excitation spectrum of a two-component Bose–Einstein condensate is obtained by Green’s function method. It is found to have two branches. In the long-wave limit, the two branches of the excitation spectrum are reduced to one phonon excitation and one single-particle excitation. With the obtained excitation spectrum and the Green’s functions, the depletion of the condensate and the ground state energy have also been calculated in this paper.
Structural evolution and stabilities of neutral and anionic clusters of lead sulfide: Joint anion photoelectron and computational studies
Authors: Koirala Pratik , Kiran Boggavarapu , Kandalam Anil K. , Fancher Charles. A. , de Clercq Helen L. , Li Xiang , Bowen Kit. H.
Published: October 2011

The geometric and electronic structures of both neutral and negatively charged lead sulfide clusters, (PbS)n/(PbS)n− (n = 2–10) were investigated in a combined anion photoelectron spectroscopy and computational study. Photoelectron spectra provided vertical detachment energies (VDEs) for the cluster anions and estimates of electron affinities (EA) for their neutral cluster counterparts, revealing a pattern of alternating EA and VDE values in which even n clusters exhibited lower EA and VDE values than odd n clusters up until n = 8. Computations found neutral lead sulfide clusters with even n to be thermodynamically more stable than their immediate (odd n) neighbors, with a consistent pattern also being found in their HOMO–LUMO gaps. Analysis of neutral cluster dissociation energies found the Pb4S4 cube to be the preferred product of the queried fragmentation processes, consistent with our finding that the lead sulfide tetramer exhibits enhanced stability; it is a magic number species. Beyond n = 10, computational studies showed that neutral (PbS)n clusters in the size range, n = 11–15, prefer two-dimensional stacking of face-sharing lead sulfide cubical units, where lead and sulfur atoms possess a maximum of five-fold coordination. The preference for six-fold coordination, which is observed in the bulk, was not observed at these cluster sizes. Taken together, the results show a preference for the formation of slightly distorted, fused cuboids among small lead sulfide clusters.
Superfluidity of electron-hole pairs in randomly inhomogeneous bilayer systems
Authors: Bezuglyj A. I. , Shevchenko S. I.
Published: October 2011

In bilayer systems, electron-hole (e–h) pairs with spatially separated components can exhibit a transition to a superfluid state. An influence of random inhomogeneities on superfluid properties of bilayer systems is considered. It is shown that ionized impurities and distortions of conducting layers reduce the density of superfluid current of e–h-pairs. In the case when the interlayer distance is less than or of the order of magnetic length, the fluctuations of the interlayer distance lead to a significant decrease of the superfluid transition temperature.
Matrix isolation study of the formation of methanol cluster structures in the spectral region of C–O and O–H stretch vibrations
Authors: Doroshenko I. Yu.
Published: October 2011

Infrared absorption spectra of methyl alcohol isolated in an argon matrix are recorded experimentally. The transformation of the structure of the spectral bands with rising matrix temperature is analyzed in the spectral region of the C–O and O–H stretch deformation vibrations (1000–1100 and 3000–3800 cm−1). The experimental data are interpreted using quantum-chemical modelling of an optimal spatial structure and of the vibrational spectra of different nano-sized methyl alcohol clusters. The structure of the clusters changes gradually as the temperature of the argon matrix is raised from 10 to 50 K.
Polaron effects and electric field dependence of the charge carrier mobility in conjugated polymers
Authors: Jakobsson Mattias , Stafström Sven
Published: October 2011

Charge transport in conjugated polymers has been investigated using Monte Carlo simulations implemented on top of the Marcus theory for donor-acceptor transition rates. In particular, polaron effects and the dependency of the mobility on the temperature and the applied electric field have been studied. The conclusions are that while the qualitative temperature dependence is similar to that predicted by Miller-Abrahams theory in the Gaussian disorder model (GDM), the electric field dependence is characterized by a crossover into the Marcus inverted region, not present in the GDM. Furthermore, available analytical approximations to describe the electric field dependence of the mobility in Marcus theory fail to fit the simulation data and hence cannot be used to directly draw conclusions about the importance of polaron effects for charge transport in conjugated polymers.
Ionizing radiation induced degradation of poly (2-methoxy-5-(2’-ethyl-hexyloxy) -1,4-phenylene vinylene) in solution
Authors: Bronze-Uhle E. S. , Batagin-Neto A. , Lavarda F. C. , Graeff C. F. O.
Published: October 2011

In this paper we investigate the causes of the chromatic alteration observed in chloroform solutions of poly (2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) after gamma ray irradiation. Structural and chemical changes were analyzed by gel permeation chromatography, fourier transform infrared spectroscopy, and proton nuclear magnetic resonance techniques and complemented by electronic structure calculations. The results indicate chlorine incorporation in the polymer structure and main chain scission after irradiation. Based on our findings we propose that the main mechanism for the blue-shifts, observed in the UV-Vis absorption spectra of MEH-PPV after irradiation, is the result of a radical attack on the polymer main chain. Gamma rays generate radicals, •Cl and •CHCl2 from chloroform radiolysis that attack preferentially the vinyl double bonds of the polymer backbone, breaking the electronic conjugation and eventually the chain. Our results indicate that oxygen does not play a major role in the effect. Electronic spectra simulations were performed based on these assumptions reproducing the UV-Vis experimental results.
Schottky barrier height tuning of silicides on p-type Si (100) by aluminum implantation and pulsed excimer laser anneal
Authors: Koh Shao-Ming , Wang Xincai , Thanigaivelan Thirumal , Henry Todd , Erokhin Yuri , Samudra Ganesh S. , Yeo Yee-Chia
Published: October 2011

We investigate the tuning of Schottky barrier height (SBH) of nickel silicide formed by pulsed excimer laser anneal of nickel on silicon implanted with aluminum (Al). A wide range of laser fluence was investigated, and it has been found that laser fluence influences the distribution of Al within the silicide and at the silicide/silicon interface. This in turn affects the effective whole SBH (ΦBp) at the silicide/silicon junction. High Al concentration at the silicide/silicon interface and high temperature for nano-second duration to achieve Al activation while keeping the Al concentration within the silicide low is vital for achieving low ΦBp. We demonstrate the achievement of one of the lowest reported ΦBp of ∼0.11 eV. This introduces a new option for forming nickel silicide contacts with reduced contact resistance at low thermal budget for possible adoption in future metal-oxide-semiconductor transistor technologies.
Multi-channel terahertz grating spectrometer with quantum-cascade laser and microbolometer array
Authors: Eichholz R. , Richter H. , Pavlov S. G. , Wienold M. , Schrottke L. , Hey R. , Grahn H. T. , Hübers H.-W.
Published: October 2011

We report on a terahertz absorption spectrometer, which combines a grating monochromator, a quantum-cascade laser (QCL), and a microbolometer camera. The emission modes of the laser are spectrally resolved by the monochromator and imaged onto the camera. An absorption cell is placed between the QCL and the monochromator, and the absorption spectrum of methanol around 3.4 THz is measured by integrating simultaneously the signal of each of its Fabry-Pérot modes as a function of the laser driving current. The frequency coverage of the spectrometer is about 20 GHz.
Multi-component nanocomposite for all-optical switching applications
Authors: Zhang Yingbo , Hu Xiaoyong , Yang Hong , Gong Qihuang
Published: October 2011

We report a multi-component nanocomposite material with large and ultrafast third-order nonlinearity, made of poly(3-hexylthiophene) doped with 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C61 and silver nanoparticles. Large nonlinear refractive index of the order of 10−7 cm2/W is reached by combining surface plasmon resonance enhancing nonlinearity and local-field enhancing nonlinearity. An ultrafast response time of 33.6 ps is achieved due to the enhanced charge transfer and exciton-exciton annihilation associated with surface plasmon resonance. An ultrafast photonic crystal all-optical switching with an ultralow pump intensity of 70 KW/cm2 is also realized.
Oxygen-enhanced wet thermal oxidation of GaAs
Authors: Bauters J. F. , Fenlon R. E. , Seibert C. S. , Yuan W. , Plunkett J. S. B. , Li J. , Hall D. C.
Published: October 2011

An oxygen-enhanced wet thermal oxidation process is used to grow smooth, uniform, insulating native oxides of GaAs. At 420 °C, a maximum linear growth rate of 4.8 nm/min is observed for oxidation in water vapor with 2000 ppm O2 added relative to the N2 carrier gas, with growth ceasing by 7000 ppm. Films as thick as 800 nm with surface roughness as low as 0.2 nm are demonstrated. In fabricated metal-oxide-semiconductor capacitors, a 412 nm thick native oxide film exhibits a factor of ∼2700 reduction in leakage current density at 1 V relative to a direct metal (Au:Ti) to GaAs contact.
Ultra-fast switching in solution processed quantum dot based non-volatile resistive memory
Authors: Kannan V. , Rhee J. K.
Published: October 2011

In this letter, we report a facile quantum dot based non-volatile resistive memory device with a switching speed of 10 ns and ON/OFF ratio of 10 000. The device showed excellent endurance characteristics for 100 000 switching cycles. Retention tests showed good stability and the devices are reproducible. Memory operating mechanism is proposed based on charge trapping in quantum dots with AlOx acting as barrier. This mechanism is supported by marked variation in capacitance value in ON and OFF states.
High efficiency resonance-based spectrum filters with tunable transmission bandwidth fabricated using nanoimprint lithography
Authors: Kaplan Alex F. , Xu Ting , Jay Guo L.
Published: October 2011

We propose a nanostructured color filter based on a metallic resonant waveguide structure capable of extremely high transmission efficiency. As an experimental demonstration, a blue and a red device were fabricated over a large area using nanoimprint lithography. Achieving transmission as high as 90% with a variable transmission bandwidth, these devices exhibit desirable features for numerous color filter applications.
Numerical calculation of fully-developed laminar flows in arbitrary cross-sections using finite difference method
Authors: Fukuchi Tsugio
Published: October 2011

The finite difference method has adequate accuracy to calculate fully-developed laminar flows in regular cross-sectional domains, but in irregular domains such flows are solved using the finite element method or structured grids. However, it has become apparent that we can use the finite difference method freely even if domains are complex. The non-slip condition on the wall must be imposed. Even in irregular domains, this boundary condition can be introduced indirectly by adding a single procedure to set the boundary condition. The calculations have similar accuracy as in regular domains. The proposed method has a wide range of applications; as a first step, fully-developed laminar flows are investigated in the paper.
Physiological and morphological factors influencing leaf, rhizome and stolon tensile strength in C4 turfgrass species
Authors: Lulli Filippo , Guglielminetti Lorenzo , Grossi Nicola , Armeni Roberto , Stefanini Sara , Volterrani Marco
Published: October 2011

The intrinsic resistance of plant tissue to several biomechanical stresses, including tensile stress, is a decisive factor in determining the wear resistance of a turfgrass species. Lignin, dry matter, starch, sugars and silica are some of the tissue constituents that have been associated with leaf and stem mechanical resistance, whereas little information is available concerning stolons and rhizomes. These organs not only enable C4 turfgrass species lateral growth, soil colonisation and injury recovery, but are also key constituents of mature swards. This study consisted in an extensive investigation on the effective leaf, stolon and rhizome tensile strength of Cynodon dactylon (L.) Pers. var. dactylon × C. transvaalensis Burt-Davy cv. Tifway 419, Zoysia matrella (L.) Merr. cv. Zeon and Paspalum vaginatum Swartz. cv. Salam, as measured with a Fédération Internationale de Football Association (FIFA)-approved dynamometer and correlating the results with laboratory investigations on key tissue constituents. Tensile strength per unit area was influenced by both tissue constituents and tissue dimension. In rhizomes and stolons, tissue breakage usually occurred in the area at the intercalary meristem at the apical zone in the immediate proximity of a node. Older tissues had higher tensile strength owing to their higher levels of lignification. Lignin was the principal constituent determining tissue tensile strength and as such it could be used as a turfgrass wear resistance predictor in the cultivar breeding stages. Stolon total soluble sugars were generally inversely proportional to lignin content and, therefore, can also be considered clear markers of tissue mechanical strength. Silica was found to have no influence on the mechanical properties tissues.
The making of autobiographical memory: Intersections of culture, narratives and identity
Authors: Fivush Robyn , Habermas Tilmann , Waters Theodore E.A. , Zaman Widaad
Published: October 2011

Autobiographical memory is a uniquely human form of memory that integrates individual experiences of self with cultural frames for understanding identities and lives. In this review, we present a theoretical and empirical overview of the sociocultural development of autobiographical memory, detailing the emergence of autobiographical memory during the preschool years and the formation of a life narrative during adolescence. More specifically, we present evidence that individual differences in parental reminiscing style are related to children's developing autobiographical narratives. Parents who structure more elaborated coherent personal narratives with their young children have children who, by the end of the preschool years, provide more detailed and coherent personal narratives, and show a more differentiated and coherent sense of self. Narrative structuring of autobiographical remembering follows a protracted developmental course through adolescence, as individuals develop social cognitive skills for temporal understanding and causal reasoning that allows autobiographical memories to be integrated into an overarching life narrative that defines emerging identity. In addition, adolescents begin to use culturally available canonical biographical forms, life scripts, and master narratives to construct a life story and inform their own autobiographical narrative identity. This process continues to be socially constructed in local interactions; we present exploratory evidence that parents help adolescents structure life narratives during coconstructed reminiscing and that adolescents use parents and families as a source for their own autobiographical content and structure. Ultimately, we argue that autobiography is a critical developmental skill; narrating our personal past connects us to our selves, our families, our communities, and our cultures.
Nse1-dependent recruitment of Smc5/6 to lesion-containing loci contributes to the repair defects of mutant complexes
Authors: Tapia-Alveal Claudia , O'Connell Matthew J.
Published: October 2011

Of the three structural maintenance of chromosomes (SMC) complexes, Smc5/6 remains the most poorly understood. Genetic studies have shown that Smc5/6 mutants are defective in homologous recombination (HR), and consistent with this, Smc5/6 is enriched at lesions. However, Smc5/6 is essential for viability, but HR is not, and the terminal phenotype of null Smc5/6 mutants is mitotic failure. Here we analyze the function of Nse1, which contains a variant RING domain that is characteristic of ubiquitin ligases. Whereas deletion of this domain causes DNA damage sensitivity and mitotic failure, serine mutations in conserved cysteines do not. However, these mutations suppress the DNA damage sensitivity of Smc5/6 hypomorphs but not that of HR mutants and remarkably decrease the recruitment of Smc5/6 to loci containing lesions marked for HR-mediated repair. Analysis of DNA repair pathways in suppressed double mutants suggests that lesions are channeled into recombination-dependent and error-free postreplication repair. Thus the HR defect in Smc5/6 mutants appears to be due to the presence of dysfunctional complexes at lesions rather than to reflect an absolute requirement for Smc5/6 to complete HR.
Membrane fusion catalyzed by a Rab, SNAREs, and SNARE chaperones is accompanied by enhanced permeability to small molecules and by lysis
Authors: Zucchi Paola C. , Zick Michael
Published: October 2011

The fusion of sealed biological membranes joins their enclosed aqueous compartments while mixing their membrane bilayers. Reconstituted fusion reactions are commonly assayed by lipid mixing, which can result from either true fusion or from lysis and its attendant reannealing of membranes. Fusion is also frequently assayed by the mixing of lumenal aqueous compartments, using probes of low molecular weight. With several probes (biotin, methylumbelliferyl-N-acetyl-α-d-neuraminic acid, and dithionite), we find that yeast vacuolar SNAREs (SNAP [Soluble NSF attachment protein] Receptors) increase the permeability of membranes to small molecules and that this permeabilization is enhanced by homotypic fusion and vacuole protein sorting complex (HOPS) and Sec17p/Sec18p, the vacuolar tethering and SNARE chaperone proteins. We now report the development of a novel assay that allows the parallel assessment of lipid mixing, the mixing of intact lumenal compartments, any lysis that occurs, and the membrane permeation of small molecules. Applying this assay to an all-purified reconstituted system consisting of vacuolar lipids, the four vacuolar SNAREs, the SNARE disassembly chaperones Sec17p and Sec18p, the Rab Ypt7p, and the Rab effector/SM protein complex HOPS, we show that true fusion is accompanied by strongly enhanced membrane permeability to small molecules and a measurable rate of lysis.
Fusion of a fluorescent protein to the pUL25 minor capsid protein of pseudorabies virus allows live-cell capsid imaging with negligible impact on infection
Authors: Bohannon Kevin P. , Sollars Patricia J. , Pickard Gary E. , Smith Gregory A.
Published: October 2011

In order to resolve the location and activity of submicroscopic viruses in living cells, viral proteins are often fused to fluorescent proteins (FPs) and visualized by microscopy. In this study, we describe the fusion of FPs to three proteins of pseudorabies virus (PRV) that allowed imaging of capsids in living cells. Included in this study are the first recombinant PRV strains expressing FP–pUL25 fusions based on a design applied to herpes simplex virus type 1 by Homa and colleagues. The properties of each reporter virus were compared in both in vitro and in vivo infection models. PRV strains expressing FP–pUL25 and FP–pUL36 preserved wild-type properties better than traditional FP–pUL35 isolates in assays of plaque size and virulence in mice. The utility of these strains in studies of axon transport, nuclear dynamics and viral particle composition are documented.
Cooperation of Escherichia coli Hfq hexamers in DsrA binding
Authors: Wang Weiwei , Wang Lijun , Zou Yang , Zhang Jiahai , Gong Qingguo , Wu Jihui , Shi Yunyu
Published: October 2011

Hfq is a bacterial post-transcriptional regulator. It facilitates base-pairing between sRNA and target mRNA. Hfq mediates DsrA-dependent translational activation of rpoS mRNA at low temperatures. rpoS encodes the stationary-phase σ factor σS, which is the central regulator in general stress response. However, structural information on Hfq–DsrA interaction is not yet available. Although Hfq is reported to hydrolyze ATP, the ATP-binding site is still unknown. Here, we report a ternary crystal complex structure of Escherichia coli Hfq bound to a major Hfq recognition region on DsrA (AU6A) together with ADP, and a crystal complex structure of Hfq bound to ADP. AU6A binds to the proximal and distal sides of two Hfq hexamers. ADP binds to a purine-selective site on the distal side and contacts conserved arginine or glutamine residues on the proximal side of another hexamer. This binding mode is different from previously postulated. The cooperation of two different Hfq hexamers upon nucleic acid binding in solution is verified by fluorescence polarization and solution nuclear magnetic resonance (NMR) experiments using fragments of Hfq and DsrA. Fluorescence resonance energy transfer conducted with full-length Hfq and DsrA also supports cooperation of Hfq hexamers upon DsrA binding. The implications of Hfq hexamer cooperation have been discussed.
TNF-stimulated MAP kinase activation mediated by a Rho family GTPase signaling pathway
Authors: Kant Shashi , Swat Wojciech , Zhang Sheng , Zhang Zhong-Yin , Neel Benjamin G. , Flavell Richard A. , Davis Roger J.
Published: October 2011

The biological response to tumor necrosis factor (TNF) involves activation of MAP kinases. Here we report a mechanism of MAP kinase activation by TNF that is mediated by the Rho GTPase family members Rac/Cdc42. This signaling pathway requires Src-dependent activation of the guanosine nucleotide exchange factor Vav, activation of Rac/Cdc42, and the engagement of the Rac/Cdc42 interaction site (CRIB motif) on mixed-lineage protein kinases (MLKs). We show that this pathway is essential for full MAP kinase activation during the response to TNF. Moreover, this MLK pathway contributes to inflammation in vivo.
WUSCHEL protein movement mediates stem cell homeostasis in the Arabidopsis shoot apex
Authors: Yadav Ram Kishor , Perales Mariano , Gruel Jérémy , Girke Thomas , Jönsson Henrik , Reddy G. Venugopala
Published: October 2011

WUSCHEL (WUS) is a homeodomain transcription factor produced in cells of the niche/organizing center (OC) of shoot apical meristems. WUS specifies stem cell fate and also restricts its own levels by activating a negative regulator, CLAVATA3 (CLV3), in adjacent cells of the central zone (CZ). Here we show that the WUS protein, after being synthesized in cells of the OC, migrates into the CZ, where it activates CLV3 transcription by binding to its promoter elements. Using a computational model, we show that maintenance of the WUS gradient is essential to regulate stem cell number. Migration of a stem cell-inducing transcription factor into adjacent cells to activate a negative regulator, thereby restricting its own accumulation, is a theme that is unique to plant stem cell niches.
Expression of ArabidopsisSHORT INTERNODES/STYLISHFamily Genes in Auxin Biosynthesis Zones of Aerial Organs Is Dependent on a GCC Box-Like Regulatory Element
Authors: Eklund D. Magnus , Cierlik Izabela , Ståldal Veronika , Claes Andrea R. , Vestman Daniel , Chandler John , Sundberg Eva
Published: October 2011

Auxin/indole-3-acetic acid (IAA) biosynthesis in Arabidopsis (Arabidopsis thaliana) plays a major role in growth responses to developmental and genetic signals as well as to environmental stimuli. Knowledge of its regulation, however, remains rudimentary, and few proteins acting as transcriptional modulators of auxin biosynthesis have been identified. We have previously shown that alteration in the expression level of the SHORT INTERNODES/STYLISH (SHI/STY) family member STY1 affects IAA biosynthesis rates and IAA levels and that STY1 acts as a transcriptional activator of genes encoding auxin biosynthesis enzymes. Here, we have analyzed the upstream regulation of SHI/STY family members to gain further insight into transcriptional regulation of auxin biosynthesis. We attempted to modulate the normal expression pattern of STY1 by mutating a putative regulatory element, a GCC box, located in the proximal promoter region and conserved in most SHI/STY genes in Arabidopsis. Mutations in the GCC box abolish expression in aerial organs of the adult plant. We also show that induction of the transcriptional activator DORNRÖSCHEN-LIKE (DRNL) activates the transcription of STY1 and other SHI/STY family members and that this activation is dependent on a functional GCC box. Additionally, STY1 expression in the strong drnl-2 mutant or the drn drnl-1 puchi-1 triple mutant, carrying knockdown mutations in both DRNL and its close paralogue DRN as well as one of their closest homologs, PUCHI, was significantly reduced, suggesting that DRNL regulates STY1 during normal plant development and that several other genes might have redundant functions.
Human leucocyte antigen‐G: expression and function in airway allergic disease
Authors: White S. R.
Published: October 2011

Human leucocyte antigen‐G (HLA‐G) is a non‐classical HLA class I molecule demonstrated originally in placental trophoblast cells. Recognition of the importance of HLA‐G to the maternal immune accommodation of the semi‐allogeneic fetus has led to investigations of its role in the suppression of immune responses and induction of tolerance. More recently, HLA‐G has been shown to have increased expression in several immunological diseases including asthma and allergic rhinitis. The focus of this review is the potential role of HLA‐G in immunological airway diseases.
Arbuscule‐containing and non‐colonized cortical cells of mycorrhizal roots undergo extensive and specific reprogramming during arbuscular mycorrhizal development
Authors: Gaude Nicole , Bortfeld Silvia , Duensing Nina , Lohse Marc , Krajinski Franziska
Published: October 2011

Most vascular plants form a mutualistic association with arbuscular mycorrhizal (AM) fungi, known as AM symbiosis. The development of AM symbiosis is an asynchronous process, and mycorrhizal roots therefore typically contain several symbiotic structures and various cell types. Hence, the use of whole‐plant organs for downstream analyses can mask cell‐specific variations in gene expression. To obtain insight into cell‐specific reprogramming during AM symbiosis, comparative analyses of various cell types were performed using laser capture microdissection combined with microarray hybridization. Remarkably, the most prominent transcriptome changes were observed in non‐arbuscule‐containing cells of mycorrhizal roots, indicating a drastic reprogramming of these cells during root colonization that may be related to subsequent fungal colonization. A high proportion of transcripts regulated in arbuscule‐containing cells and non‐arbuscule‐containing cells encode proteins involved in transport processes, transcriptional regulation and lipid metabolism, indicating that reprogramming of these processes is of particular importance for AM symbiosis.
Evolution of the genetic variability of eight French dairy cattle breeds assessed by pedigree analysis
Authors: Danchin‐Burge C. , Leroy G. , Brochard M. , Moureaux S. , Verrier E.
Published: October 2011

A pedigree analysis was performed on eight French dairy cattle breeds to assess their change in genetic variability since a first analysis completed in 1996. The Holstein, Normande and Montbéliarde breeds are selected internationally with over hundreds of thousands cows registered in the performance recording system. Three breeds are internationally selected but with limited numbers of cows in France (Brown Swiss, French Simmental and French Red Pied). The last two remaining breeds (Abondance and Tarentaise) are raised at regional level. The effective numbers of ancestors of cows born between 2004 and 2007 varied between 15 (Abondance and Tarentaise) and 51 (French Red Pied). The effective population sizes (classical approach) varied between 53 (Abondance) and 197 (French Red Pied). This article also compares the genetic variability of the ex situ (collections of the French National Cryobank) and in situ populations. The results were commented in regard to the recent history of gene flows in the different breeds as well as the existence of more or less stringent bottlenecks. Our results showed that whatever the size of the breeds, their genetic diversity impoverished quite rapidly since 1996 and they all could be considered as quite poor from a genetic diversity point of view. It shows the need for setting up cryobanks as gene reservoirs as well as sustainable breeding programmes that include loss of genetic diversity as an integrated control parameter.
Effects of fire and water availability on the emergence and recruitment of grasses, forbs and woody species in a semiarid Chaco savanna
Authors: CASILLO JOAQUÍN , KUNST CARLOS , SEMMARTIN MARÍA
Published: October 2011

In the semiarid Chaco savannas, the balance between herbaceous and woody species affects landscape configuration and ecosystem services such as forage production. Therefore, understanding the factors that control this balance is crucial for management. In a factorial experiment, we assessed the effects of fire and water availability on the emergence and recruitment of grasses, forbs and woody species. The results showed that the effects of fire and water availability on early regeneration stages differed among the three functional groups. For grasses, fire and water addition enhanced emergence when acted solely, but only the positive effects of fire were translated into a greater recruitment, irrespective of the water availability. For forbs, only water addition, when acted solely, promoted the emergence, although this effect was not translated into a greater recruitment. Lastly, in the case of woody species, both fire and water addition reduced emergence and recruitment. Our results support the notion that both fire and greater water availability would contribute to the maintenance and recovery of a grass‐dominated state of vegetation through a positive effect of fire on grasses recruitment and a general negative effect of fire and water on woody species emergence and recruitment.
Metformin‐associated lactic acidosis following acute kidney injury. Efficacious treatment with continuous renal replacement therapy
Authors: Dichtwald S. , Weinbroum A. A. , Sorkine P. , Ekstein M. P. , Dahan E.
Published: October 2011

Diabet. Med. 29, 245–250 (2012)

Introduction  Metformin is a biguanide anti‐hyperglycaemic drug. Metformin‐associated lactic acidosis may sometimes be life‐threatening. Continuous renal replacement therapy has been suggested as a method for resolving this extremely dangerous metabolic state. We describe the history of six patients admitted to the intensive care unit over a 28‐month period in pre‐shock conditions because of severe lactic acidosis, attributed to metformin‐associated lactic acidosis, and successfully treated.

Methods  We reviewed the charts of six patients admitted to our intensive care unit between January 2008 and May 2010. After initial assessment, all patients were treated with continuous renal replacement therapy. Admission serum lactate and creatinine levels, pH, need for ventilatory and cardiovascular support, as well as continuous renal replacement therapy details and length of stay were reviewed.

Results  Admission pH levels of the six patients ranged between pH 6.63 and 7.0 and their serum lactate levels ranged between 12 and 27 mmol/l; the estimated creatinine clearance ranged between 6 and 24 ml min−1 1.73 m−2. All patients required vasoactive support and five required ventilatory support. Lactate levels decreased to near zero with continuous renal replacement therapy within 7–19 h in five of the patients whose intensive care unit length of stay ranged between 1 and 5 days. One patient’s length of stay reached 11 days because of pneumonia, one died from multi‐organ failure and another suffered permanent neurological damage following prolonged cardiopulmonary resuscitation before continuous renal replacement therapy was administered. All other patients recovered without sequellae.

Conclusions  Accurate recognition of metformin‐associated lactic acidosis and prompt initiation of haemodialysis are paramount steps towards rapid recovery. Large series reports and controlled studies may better determine the optimal duration and best dialysis technique in these patients.
Physical exercise performed before bedtime improves the sleep pattern of healthy young good sleepers
Authors: Flausino Noler Heyden , Da Silva Prado Juliana Martuscelli , de Queiroz Sandra Souza , Tufik Sergio , de Mello Marco Túlio
Published: October 2011

To investigate the influence of different intensities and durations of exercise before bedtime on the sleep pattern and core body temperature of individuals considered good sleepers, we selected 17 healthy males and all underwent 5 nonconsecutive days of study. Measurements of polysomnographic parameters and core body temperature were taken at baseline and after each experimental protocol, performed at night. We found increased sleep efficiency (p = .016) among all protocols compared with baseline data and increase in REM sleep latency (p = .047) between two experiments; there was decrease in the percentage of stage 1 sleep (p = .046) and wake after sleep onset (p = .003). Core body temperature did not change significantly during the nights following exercise. Exercise performed before sleep does not impair sleep quality; rather, its practice improves sleep in good sleepers who are nonathletes, and may be considered to improve sleep pattern.
Post‐Earnings Announcement Drift: Bounds on Profitability for the Marginal Investor
Authors: Battalio Robert H. , Mendenhall Richard R.
Published: October 2011

The persistence of the post‐earnings announcement drift (PEAD) leads many to believe that trading barriers prevent investors from eliminating it. We examine two factors that have not been adequately addressed by the literature: the exact timing of earnings announcements and liquidity costs. Under a wide range of timing and cost assumptions, our results leave little doubt that over our sample period the PEAD was highly profitable after trading costs. An additional incremental investor could have earned hedged‐portfolio returns of at least 14% per year after trading costs. Over our sample period, investors did indeed leave money on the table.