bluuebunny/crossref_metadata_2025 huggingface dataset:
Remarks on the regularity criteria of three-dimensional magnetohydrodynamics system in terms of two velocity field components
Authors: Yamazaki Kazuo
Published: March 2014

We study the three-dimensional magnetohydrodynamics system and obtain its regularity criteria in terms of only two velocity vector field components eliminating the condition on the third component completely. The proof consists of a new decomposition of the four nonlinear terms of the system and estimating a component of the magnetic vector field in terms of the same component of the velocity vector field. This result may be seen as a component reduction result of many previous works [C. He and Z. Xin, “On the regularity of weak solutions to the magnetohydrodynamic equations,” J. Differ. Equ. 213(2), 234–254 (2005); Y. Zhou, “Remarks on regularities for the 3D MHD equations,” Discrete Contin. Dyn. Syst. 12(5), 881–886 (2005)].
Direct numerical simulation of multiple cycles in a valve/piston assembly
Authors: Schmitt Martin , Frouzakis Christos E. , Tomboulides Ananias G. , Wright Yuri M. , Boulouchos Konstantinos
Published: March 2014

The dynamics and multiple-cycle evolution of the incompressible flow induced by a moving piston through the open valve of a motored piston-cylinder assembly was investigated using direct numerical simulation. A spectral element solver, adapted for moving geometries using an Arbitrary Lagrange/Eulerian formulation, was employed. Eight cycles were simulated and the ensemble- and azimuthally-averaged data were found to be in good agreement with experimentally determined means and fluctuations at all measured points and times. During the first half of the intake stroke the flow field is dominated by the dynamics of the incoming jet and the vortex rings it creates. With decreasing piston speed a large central ring becomes the dominant flow feature until the top dead center. The flow field at the end of the previous cycle is found to have a dominant effect on the jet breakup and the vortex ring dynamics below the valve and on the observed significant cyclic variations. Based on statistical averaging, the evolution of the turbulent flow field during the first half of the intake stroke is dominated by the jet breakup process leading to a strongly anisotropic behavior. In the second part of the intake stroke, the decrease of the incoming jet velocity results in a more isotropic behavior.
Quantification of the strength of inertial waves in a rotating turbulent flow
Authors: Clark di Leoni P. , Cobelli P. J. , Mininni P. D. , Dmitruk P. , Matthaeus W. H.
Published: March 2014

We quantify the strength of the waves and their impact on the energy cascade in rotating turbulence by studying the wave number and frequency energy spectrum, and the time correlation functions of individual Fourier modes in numerical simulations in three dimensions in periodic boxes. From the spectrum, we find that a significant fraction of the energy is concentrated in modes with wave frequency ω ≈ 0, even when the external forcing injects no energy directly into these modes. However, for modes for which the period of the inertial waves τω is faster than the turnover time \documentclass[12pt]{minimal}\begin{document}$\tau _\textrm {NL}$\end{document}τ NL , a significant fraction of the remaining energy is concentrated in the modes that satisfy the dispersion relation of the waves. No evidence of accumulation of energy in the modes with \documentclass[12pt]{minimal}\begin{document}$\tau _\omega = \tau _\textrm {NL}$\end{document}τω=τ NL is observed, unlike what critical balance arguments predict. From the time correlation functions, we find that for modes with \documentclass[12pt]{minimal}\begin{document}$\tau _\omega < \tau _\textrm {sw}$\end{document}τω<τ sw (with \documentclass[12pt]{minimal}\begin{document}$\tau _\textrm {sw}$\end{document}τ sw the sweeping time) the dominant decorrelation time is the wave period, and that these modes also show a slower modulation on the timescale \documentclass[12pt]{minimal}\begin{document}$\tau _\textrm {NL}$\end{document}τ NL as assumed in wave turbulence theories. The rest of the modes are decorrelated with the sweeping time, including the very energetic modes with ω ≈ 0.
Electronic band gap reduction and intense luminescence in Co and Mn ion-implanted SiO2
Authors: Green R. J. , Zatsepin D. A. , St. Onge D. J. , Kurmaev E. Z. , Gavrilov N. V. , Zatsepin A. F. , Moewes A.
Published: March 2014

Cobalt and manganese ions are implanted into SiO2 over a wide range of concentrations. For low concentrations, the Co atoms occupy interstitial locations, coordinated with oxygen, while metallic Co clusters form at higher implantation concentrations. For all concentrations studied here, Mn ions remain in interstitial locations and do not cluster. Using resonant x-ray emission spectroscopy and Anderson impurity model calculations, we determine the strength of the covalent interaction between the interstitial ions and the SiO2 valence band, finding it comparable to Mn and Co monoxides. Further, we find an increasing reduction in the SiO2 electronic band gap for increasing implantation concentration, due primarily to the introduction of Mn- and Co-derived conduction band states. We also observe a strong increase in a band of x-ray stimulated luminescence at 2.75 eV after implantation, attributed to oxygen deficient centers formed during implantation.
Electrical conductivity anomaly and X-ray photoelectron spectroscopy investigation of YCr1−xMnxO3 negative temperature coefficient ceramics
Authors: Zhang Bo , Zhao Qing , Chang Aimin , Li Yiyu , Liu Yin , Wu Yiquan
Published: March 2014

Electrical conductivity anomaly of perovskite-type YCr1−xMnxO3 negative temperature coefficient (NTC) ceramics produced by spark plasma sintering (SPS) has been investigated by using defect chemistry theory combination with X-ray photoelectron spectroscopy (XPS) analysis. From the results of the lnρ-1/T curves and the XPS analysis, it can be considered that YCr1−xMnxO3 ceramics exhibit the hopping conductivity. The major carriers in YCrO3 are holes, which are compensated by the oxygen vacancies produced due to the introduction of Mn ions. The Mn4+ ion contents increase monotonically in the range of 0.2 ≤ x ≤ 0.5. The resistivity increases at first and then decreases with increasing Mn contents, which has the same varying tendency with activation energy. The electrical conductivity anomaly appearing in these ceramics may be due to the variation of Cr4+ and Mn4+ ions concentration as Mn content changes.
Thermal conductivity of simple liquids: Origin of temperature and packing fraction dependences
Authors: Ishii Yoshiki , Sato Keisuke , Salanne Mathieu , Madden Paul A. , Ohtori Norikazu
Published: March 2014

The origin of both weak temperature dependence and packing fraction dependence of T1/4η3/2 in the thermal conductivity of the simple Lennard-Jones (LJ) liquid is explored. In order to discuss the relative contributions from attractive or repulsive part of the interaction potential separately, the thermal conductivity of a series of Weeks-Chandler-Anderson (WCA) fluids is calculated by molecular dynamics simulations. The results show that the repulsive part plays the main role in the heat conduction, while the attractive part has no direct effect on the thermal conductivity for a given packing fraction. By investigating WCA fluids with potentials of varying softness, we explain the difference observed between the LJ liquids such as argon and Coulombic liquids such as NaCl.
Thermoelectric study of crossroads material MnTe via sulfur doping
Authors: Xie Wenjie , Populoh Sascha , Gałązka Krzysztof , Xiao Xingxing , Sagarna Leyre , Liu Yufei , Trottmann Matthias , He Jian , Weidenkaff Anke
Published: March 2014

Here, we report thermoelectric study of crossroads material MnTe via iso-electronic doping S on the Te-site. MnTe1-xSx samples with nominal S content of x = 0.00, 0.05, and 0.10 were prepared using a melt-quench method followed by pulverization and spark plasma sintering. The X-ray powder diffraction, scanning electron microscopy, and ZAF-corrected compositional analysis confirmed that S uniformly substitutes Te up to slightly over 2%. A higher content of S in the starting materials led to the formation of secondary phases. The thermoelectric properties of MnTe1-xSx samples were characterized by means of Seebeck coefficient, electrical conductivity, and thermal conductivity measurements from 300 K to 773 K. Furthermore, Hall coefficient measurements and a single parabolic band model were used to help gain insights on the effects of S-doping on the scattering mechanism and the carrier effective mass. As expected, S doping not only introduced hole charge carriers but also created short-range defects that effectively scatter heat-carrying phonons at elevated temperatures. On the other hand, we found that S doping degraded the effective mass. As a result, the ZT of MnTe0.9S0.1 was substantially enhanced over the pristine sample near 400 K, while the improvement of ZT became marginal at elevated temperatures. A ZT ∼ 0.65 at 773 K was obtained in all three samples.
A 2-in. mosaic wafer made of a single-crystal diamond
Authors: Yamada H. , Chayahara A. , Mokuno Y. , Kato Y. , Shikata S.
Published: March 2014

We synthesized a mosaic diamond wafer 2 in. in size (40 × 60 mm2), which consisted of 24 single-crystal diamond (SCD) plates 10 × 10 mm2 in area, by using microwave plasma chemical vapor deposition. Even by using a cloning technique, cracking frequently occurred and the non-uniformity was remarkable for wafers that were larger than 1 in. in size. This has not been observed in smaller samples before. Appropriate crystallographic directions could avoid the cracking and is one of the predominant factors in fabricating large area SCD wafers. Comparison with numerical simulations highlighted the importance of uniformity of the substrate temperature distribution on the uniformity of the growth.
Numerical simulation of the sustaining discharge in radio frequency hollow cathode discharge in argon
Authors: Jiang Xin-Xian , He Feng , Chen Qiang , Ge Teng , Ouyang Ji-Ting
Published: March 2014

In this paper, a two-dimensional fluid model was developed to study the radio frequency (RF) hollow cathode discharge (HCD) in argon at 1 Torr. The evolutions of the particle density distribution and the ionization rate distribution in RF HCD at 13.56 MHz indicate that the discharge mainly occurs inside the hollow cathode. The spatio-temporal distributions of the ionization rate and the power deposition within the hollow cathode imply that sheath oscillation heating is the primary mechanism to sustain the RF HCD, whereas secondary electron emission plays a negligible role. However, as driving frequency decreases, secondary electron heating becomes a dominant mechanism to sustain the discharge in RF hollow cathode.
Nonreciprocal dispersion of spin waves in ferromagnetic thin films covered with a finite-conductivity metal
Authors: Mruczkiewicz M. , Krawczyk M.
Published: March 2014

We study the effect of one-side metallization of a uniform ferromagnetic thin film on its spin-wave dispersion relation in the Damon–Eshbach geometry. Due to the finite conductivity of the metallic cover layer on the ferromagnetic film, the spin-wave dispersion relation may be nonreciprocal only in a limited wave-vector range. We provide an approximate analytical solution for the spin-wave frequency, discuss its validity, and compare it with numerical results. The dispersion is analyzed systematically by varying the parameters of the ferromagnetic film, the metal cover layer and the value of the external magnetic field. The conclusions drawn from this analysis allow us to define a structure based on a 30 nm thick CoFeB film with an experimentally accessible nonreciprocal dispersion relation in a relatively wide wave-vector range.
A test for a conjecture on the nature of attractors for smooth dynamical systems
Authors: Gottwald Georg A. , Melbourne Ian
Published: March 2014

Dynamics arising persistently in smooth dynamical systems ranges from regular dynamics (periodic, quasiperiodic) to strongly chaotic dynamics (Anosov, uniformly hyperbolic, nonuniformly hyperbolic modelled by Young towers). The latter include many classical examples such as Lorenz and Hénon-like attractors and enjoy strong statistical properties. It is natural to conjecture (or at least hope) that most dynamical systems fall into these two extreme situations. We describe a numerical test for such a conjecture/hope and apply this to the logistic map where the conjecture holds by a theorem of Lyubich, and to the 40-dimensional Lorenz-96 system where there is no rigorous theory. The numerical outcome is almost identical for both (except for the amount of data required) and provides evidence for the validity of the conjecture.
Distinguishing triplet energy transfer and trap-assisted recombination in multi-color organic light-emitting diode with an ultrathin phosphorescent emissive layer
Authors: Xue Qin , Xie Guohua , Liu Shouyin , Chen Ping , Zhao Yi , Liu Shiyong
Published: March 2014

An ultrathin layer of deep-red phosphorescent emitter tris(1-phenylisoquinoline) iridium (III) (Ir(piq)3) is inserted within different positions of the electron blocking layer fac-tris (1-phenylpyrazolato-N,C2′)-iridium(III) (Ir(ppz)3) to distinguish the contribution of the emission from the triplet exciton energy transfer/diffusion from the adjacent blue phosphorescent emitter and the trap-assisted recombination from the narrow band-gap emitter itself. The charge trapping effect of the narrow band-gap deep-red emitter which forms a quantum-well-like structure also plays a role in shaping the electroluminescent characteristics of multi-color organic light-emitting diodes. By accurately controlling the position of the ultrathin sensing layer, it is considerably easy to balance the white emission which is quite challenging for full-color devices with multiple emission zones. There is nearly no energy transfer detectable if 7 nm thick Ir(ppz)3 is inserted between the blue phosphorescent emitter and the ultrathin red emitter.
Effect of ambient gas pressure and nature on the temporal evolution of aluminum laser-induced plasmas
Authors: Dawood M. S. , Margot Joëlle
Published: March 2014

Time-resolved analysis of emission spectra, electron densities and excitation temperatures of Aluminum laser induced plasmas produced in argon, nitrogen and helium at different pressures have been studied experimentally. The plasma emission intensity is found to be strongly affected by the plume confinement and differs with the nature of the ambient gas and its pressure. Our observations show that both electron density and excitation temperature increase with the ambient gas pressure. In addition, Argon was found to produce the highest plasma density and temperature and Helium the lowest, while Nitrogen yields intermediate values.
Effects of obliqueness and strong electrostatic interaction on linear and nonlinear propagation of dust-acoustic waves in a magnetized strongly coupled dusty plasma
Authors: Shahmansouri M. , Mamun A. A.
Published: March 2014

Linear and nonlinear propagation of dust-acoustic waves in a magnetized strongly coupled dusty plasma is theoretically investigated. The normal mode analysis (reductive perturbation method) is employed to investigate the role of ambient/external magnetic field, obliqueness, and effective electrostatic dust-temperature in modifying the properties of linear (nonlinear) dust-acoustic waves propagating in such a strongly coupled dusty plasma. The effective electrostatic dust-temperature, which arises from strong electrostatic interactions among highly charged dust, is considered as a dynamical variable. The linear dispersion relation (describing the linear propagation characteristics) for the obliquely propagating dust-acoustic waves is derived and analyzed. On the other hand, the Korteweg-de Vries equation describing the nonlinear propagation of the dust-acoustic waves (particularly, propagation of dust-acoustic solitary waves) is derived and solved. It is shown that the combined effects of obliqueness, magnitude of the ambient/external magnetic field, and effective electrostatic dust-temperature significantly modify the basic properties of linear and nonlinear dust-acoustic waves. The results of this work are compared with those observed by some laboratory experiments.
Piezoelectric energy harvester converting strain energy into kinetic energy for extremely low frequency operation
Authors: Kwon Dae-Sung , Ko Hee-Jin , Kim Min-Ook , Oh Yongkeun , Sim Jaesam , Lee Kyounghoon , Cho Kyung-Ho , Kim Jongbaeg
Published: March 2014

In this study, we developed a flexible energy harvester that uses the frequency up-conversion mechanism. The harvester is composed of a flexible piezoelectric cantilever and substrate, and it can scavenge energy from deformation or strain by converting it into a mechanical vibration of the cantilever. We found experimentally that the output voltage of the harvester not affected by an input frequency as long as the strain was large enough, and there was no lower limit of the input frequency. The critical strain, i.e., the threshold radius of curvature of the harvester, could be modulated by adjusting magnetic force; therefore, it is possible to optimally apply the harvester to various deformation ranges. The maximum and average power density at 0.5 Hz of input frequency was measured to be 320 μW/cm2 and 6.8 μW/cm2 for a resistive load of 10 MΩ.
Fabrication of silicon nanotip arrays with high aspect ratio by cesium chloride self-assembly and dry etching
Authors: Zhang Xinshuai , Liu Jing , Wang Bo , Zhang Tianchong , Yi Futing
Published: March 2014

Nanotip arrays with high aspect ratio, which have attracted much attention due to their potential applications, have been fabricated by many methods. Dry etching combined with self-assembly masks is widely used because of the convenience of dry etching and high throughput of self-assembly. In this paper, we report a method combining Cesium Chloride (CsCl) self-assembly with inductively coupled plasma (ICP) dry etching to fabricate silicon nanotip arrays with high aspect ratio and silicon nanotip arrays with aspect ratio 15 have been achieved after optimization of all parameters.
High resolution capacitance detection circuit for rotor micro-gyroscope
Authors: Ren Ming-Yuan , Zhang Hai-Feng , Liu Xiao-Wei , Mao Zhi-Gang
Published: March 2014

Conventional methods for rotor position detection of micro-gyroscopes include common exciting electrodes (single frequency) and common sensing electrodes (frequency multiplex), but they have encountered some problems. So we present a high resolution and low noise pick-off circuit for micro-gyroscopes which utilizes the time multiplex method. The detecting circuit adopts a continuous-time current sensing circuit for capacitance measurement, and its noise analysis of the charge amplifier is introduced. The equivalent output noise power spectral density of phase-sensitive demodulation is 120 nV/Hz1/2. Tests revealed that the whole circuitry has a relative capacitance resolution of 1 × 10−8.
Mouse ovarian tissue vitrification on copper electron microscope grids versus slow freezing: a comparative ultrastructural study
Authors: Topal-Celikkan Ferda , Ozkavukcu Sinan , Balci Deniz , Serin-Kilicoglu Sibel , Atabenli-Erdemli Esra
Published: March 2014

There are many reasons, including cancer therapy, for premature ovarian failure and infertility. Oocyte, embryo and ovarian cryopreservation are current options for fertility preservation. Ovarian tissue cryopreservation is essential in patients whose cancer therapy cannot be delayed, including prepubertal girls, and is mostly performed using slow freezing. In the present study, mouse ovarian tissues were vitrified on copper electron microscope grids (n = 18) or conventionally slow frozen (n = 18). Post-thaw tissues were examined histologically using light and electron microscopy and compared with the control group. According to light microscopy observations, antral follicles were found to be better preserved with the slow freezing technique rather than vitrification. Electron microscopy revealed swollen mitochondria in the oocyte cytoplasm, condensations in the zona pellucida, breakages in the junctions of granulosa cells and vacuolisation in the extracellular space in pathologic follicles, which were relatively more frequent, in the vitrification group after thawing. These results indicate that ovarian slow freezing is preferable than vitrification on copper electron microscope grids, especially for larger follicles. Conversely, vitrification of ovarian pieces using cooper grids is user-friendly and provided good protection for primordial follicles and stromal cells. There is a need for further studies into advanced tissue vitrification techniques and carriers.
Lexical semantics of transitivizer light verbs in Telugu
Authors: Balusu Rahul
Published: March 2014

This chapter examines the kind of meanings that are uniformly present in constructions involving a certain variety of light verbs in Telugu – transitivizer light verbs. The meanings that are inalienably constant in both the verbal and the nominal complex predicates that these light verbs form are the inceptual meanings- emphasizing inception or beginning, continuation or progression, and completion or end-point. These meanings can be directly linked, and are further evidence for the structural decomposition of the verbal domain into 3 subparts or projections (First Phase Syntax, Ramchand 2008) – initP (introduces causation), procP (specifies the process), and resP (gives the result state). The semantics of this structure is what I claim gives rise to the inceptual meanings.
PK10453, a Nonselective Platelet‐Derived Growth Factor Receptor Inhibitor, Prevents the Progression of Pulmonary Arterial Hypertension
Authors: Medarametla Venkatrao , Festin Stephen , Sugarragchaa Chuluunbaatar , Eng Alexander , Naqwi Amir , Wiedmann Timothy , Zisman Lawrence S.
Published: March 2014

The platelet‐derived growth factor (PDGF) signaling pathway has been found to be activated in human pulmonary arterial hypertension (PAH) and in animal models of the disease. Our study tested the hypothesis that a novel, nonselective inhaled PDGF receptor inhibitor, PK10453, would decrease pulmonary hypertension both in the rat monocrotaline (MCT) model and the rat MCT plus pneumonectomy (MCT+PN) model of PAH. PK10453, delivered by inhalation for 4 (D4)‐ and 8 (D8)‐minute exposures 3 times a day for 2 weeks, decreased right ventricular systolic pressure (RVSP) in both the rat MCT and rat MCT+PN models: RVSP was 80.4 ± 2.6 mmHg in the vehicle MCT group (n = 6), 44.4 ± 5.8 mmHg in the D4 MCT group (n = 6), and 37.1 ± 4.5 mmHg in the D8 MCT group (n = 5; P < 0.001 vs. vehicle); RVSP was 75.7 ± 7.1 mmHg in the vehicle MCT+PN group (n = 9), 40.4 ± 2.7 mmHg in the D4 MCT+PN group (n = 10), and 43.0 ± 3.0 mmHg in the D8 MCT+PN group (n = 8; P < 0.001). In the rat MCT+PN model, continuous telemetry monitoring of pulmonary artery pressures also demonstrated that PK10453 prevented the progression of PAH. Imatinib given by inhalation was equally effective in the MCT model but was not effective in the MCT+PN model. Immunohistochemistry demonstrated increased activation of the PDGFβ receptor compared to the PDGFα receptor in neointimal and perivascular lesions found in the MCT+PN model. We show that imatinib is selective for the PDGFα receptor, whereas PK10453 has a lower half‐maximal inhibitor concentration (IC50) for inhibition of kinase activity of both the PDGFα and PDGFβ receptors compared to imatinib. In conclusion, PK10453, when delivered by inhalation, significantly decreased the progression of PAH in the rat MCT and MCT+PN models. Nonselective inhibition of both the PDGFα and PDGFβ receptors may have a therapeutic advantage over selective PDGFα receptor inhibition in PAH.
Multiple inputs control sulfur-containing amino acid synthesis inSaccharomyces cerevisiae
Authors: Sadhu Meru J. , Moresco James J. , Zimmer Anjali D. , Yates John R. , Rine Jasper
Published: March 2014

In Saccharomyces cerevisiae, transcription of the MET regulon, which encodes the proteins involved in the synthesis of the sulfur-containing amino acids methionine and cysteine, is repressed by the presence of either methionine or cysteine in the environment. This repression is accomplished by ubiquitination of the transcription factor Met4, which is carried out by the SCF(Met30) E3 ubiquitin ligase. Mutants defective in MET regulon repression reveal that loss of Cho2, which is required for the methylation of phosphatidylethanolamine to produce phosphatidylcholine, leads to induction of the MET regulon. This induction is due to reduced cysteine synthesis caused by the Cho2 defects, uncovering an important link between phospholipid synthesis and cysteine synthesis. Antimorphic mutants in S-adenosyl-methionine (SAM) synthetase genes also induce the MET regulon. This effect is due, at least in part, to SAM deficiency controlling the MET regulon independently of SAM's contribution to cysteine synthesis. Finally, the Met30 protein is found in two distinct forms whose relative abundance is controlled by the availability of sulfur-containing amino acids. This modification could be involved in the nutritional control of SCF(Met30) activity toward Met4.
Selective mRNA translation during eIF2 phosphorylation induces expression of IBTKα
Authors: Baird Thomas D. , Palam Lakshmi Reddy , Fusakio Michael E. , Willy Jeffrey A. , Davis Christopher M. , McClintick Jeanette N. , Anthony Tracy G. , Wek Ronald C.
Published: March 2014

Disruption of protein folding in the endoplasmic reticulum (ER) triggers the unfolded protein response (UPR), a transcriptional and translational control network designed to restore protein homeostasis. Central to the UPR is PKR-like ER kinase (PERK/EIF2AK3) phosphorylation of the α subunit of eIF2 (eIF2α∼P), which represses global translation coincident with preferential translation of mRNAs, such as activating transcription factor 4 (ATF4) and C/EBP-homologous protein (CHOP), that serve to implement UPR transcriptional regulation. In this study, we used sucrose gradient ultracentrifugation and a genome-wide microarray approach to measure changes in mRNA translation during ER stress. Our analysis suggests that translational efficiencies vary over a broad range during ER stress, with the majority of transcripts being either repressed or resistant to eIF2α∼P, whereas a notable cohort of key regulators are subject to preferential translation. From the latter group, we identified the α isoform of inhibitor of Bruton's tyrosine kinase (IBTKα) as being subject to both translational and transcriptional induction during eIF2α∼P in both cell lines and a mouse model of ER stress. Translational regulation of IBTKα mRNA involves stress-induced relief of two inhibitory upstream open reading frames in the 5′-leader of the transcript. Depletion of IBTKα by short hairpin RNA reduced viability of cultured cells coincident with increased caspase 3/7 cleavage, suggesting that IBTKα is a key regulator in determining cell fate during the UPR.
The Role of Migration in the Evolution of Phenotypic Switching
Authors: Carja Oana , Furrow Robert E. , Feldman Marcus W.
Published: March 2014

Stochastic switching is an example of phenotypic bet-hedging, where an individual can switch between different phenotypic states in a fluctuating environment. Although the evolution of stochastic switching has been studied when the environment varies temporally, there has been little theoretical work on the evolution of phenotypic switching underbothspatially and temporally fluctuating selection pressures. Here we use a population genetic model to explore the interaction of temporal and spatial variation in the evolutionary dynamics of phenotypic switching. We find that spatial variation in selection is important; when selection pressures are similar across space, migration can decrease the rate of switching, but when selection pressures differ spatially, increasing migration between demes can facilitate the evolution of higher rates of switching. These results may help explain the diverse array of non-genetic contributions to phenotypic variability and phenotypic inheritance observed in both wild and experimental populations.
Mpl expression on megakaryocytes and platelets is dispensable for thrombopoiesis but essential to prevent myeloproliferation
Authors: Ng Ashley P. , Kauppi Maria , Metcalf Donald , Hyland Craig D. , Josefsson Emma C. , Lebois Marion , Zhang Jian-Guo , Baldwin Tracey , Di Rago Ladina , Hilton Douglas J. , Alexander Warren S.
Published: March 2014

Thrombopoietin (TPO) acting via its receptor Mpl is the major cytokine regulator of platelet number. To precisely define the role of specific hematopoietic cells in TPO dependent hematopoiesis, we generated mice that express the Mpl receptor normally on stem/progenitor cells but lack expression on megakaryocytes and platelets (MplPF4cre/PF4cre).MplPF4cre/PF4cremice displayed profound megakaryocytosis and thrombocytosis with a remarkable expansion of megakaryocyte-committed and multipotential progenitor cells, the latter displaying biological responses and a gene expression signature indicative of chronic TPO over-stimulation as the underlying causative mechanism, despite a normal circulating TPO level. Thus, TPO signaling in megakaryocytes is dispensable for platelet production; its key role in control of platelet number is via generation and stimulation of the bipotential megakaryocyte precursors. Nevertheless, Mpl expression on megakaryocytes and platelets is essential to prevent megakaryocytosis and myeloproliferation by restricting the amount of TPO available to stimulate the production of megakaryocytes from the progenitor cell pool.

Significance statement

Blood platelets, the small circulating cells that co-ordinate hemostasis, are produced by specialized bone marrow cells called megakaryocytes. The cytokine thrombopoietin (TPO) is a key regulator of platelet production acting via its specific cell receptor, Mpl. Via genetic modification of theMplallele in mice, we precisely define the bone marrow cells that express Mpl and, by genetically removing Mpl from megakaryocytes and platelets, we show TPO signaling via Mpl is not required in megakaryocytes for their expansion, maturation or platelet production. Rather, Mpl expression on megakaryocytes is essential for regulating TPO availability in the bone marrow microenvironment to prevent myeloproliferation, a model we suggest is important for human disease.
Hypoosmotic Expression of Dunaliella bardawil ζ-Carotene Desaturase Is Attributed to a Hypoosmolarity-Responsive Element Different from Other Key Carotenogenic Genes
Authors: Lao Yong-Min , Xiao Lan , Luo Li-Xin , Jiang Jian-Guo
Published: March 2014

Some key carotenogenic genes (crts) in Dunaliella bardawil are regulated in response to salt stress partly due to salt-inducible cis-acting elements in their promoters. Thus, we isolated and compared the ζ-carotene desaturase (Dbzds) promoter with other crts promoters including phytoene synthase (Dbpsy), phytoene desaturase (Dbpds), and lycopene β-cyclase1 (DblycB1) to identify salt-inducible element(s) in the Dbzds promoter. In silico analysis of the Dbzds promoter found several potential cis-acting elements, such as abscisic acid response element-like sequence, myelocytomatosis oncogene1 recognition motif, AGC box, anaerobic motif2, and activation sequence factor1 binding site. Remarkably, instead of salt-inducible elements, we found a unique regulatory sequence architecture in the Dbzds promoter: a hypoosmolarity-responsive element (HRE) candidate followed by a potential hypoosmolarity-inducible factor GBF5 binding site. Deletion experiments demonstrated that only HRE, but not the GBF5 binding site, is responsible for hypoosmotic expression of the fusion of Zeocin resistance gene (ble) to the enhanced green fluorescent protein (egfp) chimeric gene under salt stress. Dbzds transcripts were in accordance with those of ble-egfp driven by the wild-type Dbzds promoter. Consequently, Dbzds is hypoosmotically regulated by its promoter, and HRE is responsible for this hypoosmotic response. Finally, the hypoosmolarity mechanism of Dbzds was studied by comparing transcript profiles and regulatory elements of Dbzds with those of Dbpsy, Dbpds, DblycB1, and DblycB2, revealing that different induction characteristics of crts may correlate with regulatory sequence architecture.
Threonine 57 is required for the post-translational activation ofEscherichia coliaspartate α-decarboxylase
Authors: Webb Michael E. , Yorke Briony A. , Kershaw Tom , Lovelock Sarah , Lobley Carina M. C. , Kilkenny Mairi L. , Smith Alison G. , Blundell Tom L. , Pearson Arwen R. , Abell Chris
Published: March 2014

Aspartate α-decarboxylase is a pyruvoyl-dependent decarboxylase required for the production of β-alanine in the bacterial pantothenate (vitamin B5) biosynthesis pathway. The pyruvoyl group is formedviathe intramolecular rearrangement of a serine residue to generate a backbone ester intermediate which is cleaved to generate an N-terminal pyruvoyl group. Site-directed mutagenesis of residues adjacent to the active site, including Tyr22, Thr57 and Tyr58, reveals that only mutation of Thr57 leads to changes in the degree of post-translational activation. The crystal structure of the site-directed mutant T57V is consistent with a non-rearranged backbone, supporting the hypothesis that Thr57 is required for the formation of the ester intermediate in activation.
miR‐424 levels in hair shaft are increased in psoriatic patients
Authors: Tsuru Yasuo , Jinnin Masatoshi , Ichihara Asako , Fujisawa Akihiko , Moriya Chikako , Sakai Keisuke , Fukushima Satoshi , Ihn Hironobu
Published: March 2014

Objective diagnostic markers have not been in clinical use for psoriasis. In this study, we investigated the levels of miR‐424 in hair roots and hair shafts in psoriatic patients, and evaluated the possibility that miR‐424 can be a biomarker of the disease. A single hair root and five pieces of hair shafts (~5 cm in length) were obtained from the non‐lesional occiput of each individual of 26 psoriatic patients. Control hair samples were collected from nine normal subjects. Samples from 10 atopic dermatitis patients were also included as the disease control. miR‐424 levels were determined by quantitative real‐time polymerase chain reaction. Hair shaft miR‐424 levels were significantly upregulated only in patients with psoriasis compared with normal controls and those with atopic dermatitis. By receiver–operator curve analysis of hair shaft miR‐424 to distinguish psoriatic patients from normal subjects, the area under the curve was 0.77. However, relative miR‐424 levels were not correlated with disease activity markers including disease duration, body surface area and Psoriasis Area and Severity Index. Hair root miR‐424 was not useful for evaluating both diagnosis and severity of the disease. Our results indicated hair shaft miR‐424 levels may be useful as a diagnostic marker of psoriasis.
Optimizing study design for multi‐species avian monitoring programmes
Authors: Sanderlin Jamie S. , Block William M. , Ganey Joseph L.
Published: March 2014

Many monitoring programmes are successful at monitoring common species, whereas rare species, which are often of highest conservation concern, may be detected infrequently. Study designs that increase the probability of detecting rare species at least once over the study period, while collecting adequate data on common species, strengthen programme ability to address community‐wide hypotheses about how an ecosystem functions or responds to management actions. Study design guidelines exist for single‐species occupancy models, but practical guidance for monitoring species communities is needed. Single‐species population‐level designs are necessarily optimal for targeted species, whereas community study designs may be optimal for the assemblage of species, but not for every species within the community. Our objective was to provide a general optimization tool for multi‐species models and to illustrate this tool using data from two avian community studies.

We conducted a simulation study with a Bayesian hierarchical model to explore design and cost trade‐offs for avian community monitoring programmes. We parameterized models using two long‐term avian studies from Arizona, USA and evaluated bias and accuracy for different combinations of species in the regional species pool and sampling design combinations of number of sites and sampling occasions. We optimized for maximum accuracy of species richness, detection probability and occupancy probability of rare species, given a fixed budget.

Statistical properties for species richness and detection probability of species within the community were driven more by sampling occasions, whereas rare species occupancy probability was influenced more by percentage of area sampled. These results are consistent with results from single‐species models, suggesting some similarities between community‐level and single‐species models with occupancy and detection.

Synthesis and applications. Study designs must be cost‐efficient while providing reliable knowledge. Researchers and managers have limited funds for collecting data. Our template can be used by researchers and managers to evaluate trade‐offs and efficiencies for allocating samples between the number of occasions and sites in multi‐species studies, and allow them to identify the optimal study design in order to achieve specific study objectives.
Polyphenols from olive mill waste affect biofilm formation and motility in Escherichia coli K‐12
Authors: Carraro Lisa , Fasolato Luca , Montemurro Filomena , Martino Maria Elena , Balzan Stefania , Servili Maurizio , Novelli Enrico , Cardazzo Barbara
Published: March 2014

Olive mill wastes are sources of phenolic compounds with a wide array of biological activities, including antimicrobial effects. A potential option for bioremediation to overcome ecological problems is the reutilization of these natural compounds in food production. The aim of this work was to gain a better understanding of the antimicrobial mode of action of a phenols extract from olive vegetation water (PEOVW) at molecular level by studying Escherichia coli as a model microorganism. Genome‐wide transcriptional analysis was performed on E. coli K‐12 exposed to PEOVW. The repression of genes for flagellar synthesis and the involvement of genes linked to biofilm formation and stress response were observed. Sub‐inhibitory concentrations of PEOVW significantly decreased biofilm formation, swarming and swimming motility, thus confirming the gene expression data. This study provides interesting insights on the molecular action of PEOVW on E. coli K‐12. Given these anti‐biofilm properties and considering that biofilm formation is a serious problem for the food industry and human health, PEOVW has proved to be a high‐value natural product.
Effect of Telmisartan on Atrial Fibrillation Recurrences in Patients with Hypertension: A Systematic Review and Meta‐Analysis
Authors: Pan Gaofeng , Zhou Xuefeng , Zhao Jinping
Published: March 2014

Background

The systematic review and meta‐analysis are to evaluate the effect of t Telmisartan on atrial fibrillation (AF) recurrences in hypertensive patients with paroxysmal AF.

Methods

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched. Random controlled trials (RCTs) were conducted in which telmisartan was compared to other antihypertensive drugs for AF recurrences prevention in hypertensive patients with paroxysmal AF. A systematic review and meta‐analysis based on aggregate data extracted from the included studies were carried out to assess the telmisartan in preventing AF relapse. The efficacy outcome was the incidence of AF recurrences. Hazard ratios (HRs) were calculated from published summary statistics and combined to give pooled estimates of efficacy.

Results

This meta‐analysis comprised four studied including 1050 hypertensive patients (537 men and 513 women; mean age 63; mean blood pressure (BP) 156/94 mmHg). With the similar BP control, the AF recurrences rate was significantly lower in the telmisartan‐treated patients than in the other antihypertensive drugs‐treated patients (HR 0.54, CI 0.34–0.86, P < 0.05).

Conclusion

The results of this review and meta‐analysis indicate that telmisartan seems to be more effective than other antihypertensive drugs in preventing AF recurrences among hypertensive patients with paroxysmal AF.
Privatisation and Franchising of British Train Operations
Authors: Li Carmen A. , Stittle John
Published: March 2014

TheRailways Act 1993privatised the British railways industry resulting in the separation of ownership and control of the railway infrastructure (track, signals and stations) from that of passenger train operations. The Great North Eastern Railway (GNER), a major train operator, was unable to meet its contractual obligations shortly after successfully re‐tendering for its second franchise. By referring to the organisational form and structure of the franchising process, this paper discusses the main financial and operational problems that specifically contributed to the collapse of GNER. In particular, the paper argues that the fragmented structure of privatised train operations, the lack of industry coordination and the inherent problems of franchising an essential transport service explain the demise of GNER and have undermined the general objectives of railway privatisation. Overall, the paper highlights that privatisation of train services has failed to deliver both travelling benefits for the public and financial benefits to the state.
An Experimental Study on the Effect of Budget Information on Balanced Scorecard Preparer Individual Learning
Authors: Khalifeh Chadi Joseph , Sivabalan Prabhu
Published: March 2014

We examine whether budgets affect individual learning in balanced scorecard (BSC) preparers for the purposes of scorecard target setting. Control systems research has called for studies examining the impact of multiple controls on common decision‐making phenomena. Given this, are there other cybernetic controls (budgets) that might influence the decisions of BSC preparers? From an experimental study involving 235 postgraduate university candidates, our findings suggest that the awareness of progressively greater budget information amongst BSC users in high uncertainty environments engenders greater individual learning about the organisation, altering BSC preparer target‐setting choices. Interestingly, this learning does not necessarily lead to better budget‐actual outcomes, but informs BSC preparers of the constraints facing the organisation from a funding ‘supply side’ perspective. The oft‐criticised budget, even within high uncertainty conditions, facilitates learning in a BSC system originally purported to replace or advance the traditional system. Finally, we contribute more broadly to a growing literature evidencing the appropriateness of budgets in flexible environments, by arguing for its impact on other performance management systems.
A longitudinal examination of emotion regulation: pathways to anxiety and depressive symptoms in urban minority youth
Authors: Folk Johanna B. , Zeman Janice L. , Poon Jennifer A. , Dallaire Danielle H.
Published: March 2014

Background

Difficulty regulating emotions is a symptom of many psychological disorders yet little research has examined the longitudinal relations of particular facets of emotion regulation (ER) that may differentiate between internalizing symptoms.

Method

At‐risk youth (n = 102; 44.1% boys, 77.5% Black; Mage = 9.65) and caregivers (n = 74; 87.1% mothers) participated in a 2‐year longitudinal study. Children reported on their ER, and children and caregivers on symptomatology.

Results

Different patterns, varying by emotion facet (dysregulation, inhibition, coping) and type (anger, sadness, worry), predicted anxiety and depression symptoms.

Conclusions

Anxiety and depression are entities with distinct patterns of emotion‐related antecedents.
Structure–Function Relationship of Val/Arg‐rich Peptides: Effects of Net Charge and Pro on Activity
Authors: Ma Qingquan , Jiao Wenjing , Lv Yinfeng , Dong Na , Zhu Xin , Shan Anshan
Published: March 2014

Our previous study reported Val/Arg‐rich peptides, and the relationship was linear between hydrophobicity and antimicrobial potency within a certain range. Here, we further develop a new series of analogs to investigate the effect of net charge and Pro residue on activity. Replacement of Gly with Ala or Pro led to the decrease in antimicrobial activity. The substitution of Gly with Ala retained its hemolytic activity, while the substitution with Pro significantly decreased the toxicity, suggesting positive effect of Pro on hemolytic activity. The increase in net charge from +4 to +6 significantly improved antimicrobial activity and decreased the hemolysis. However, antibacterial and hemolytic activities were not affected by increasing the net charge from +6 to +8, indicating a moderate net positive charge. The peptides produced larger blue shifts in PE/PG than in PC/cholesterol, suggesting a stronger affinity with negatively charged membrane over zwitterionic membrane. Lowering the net charge or insert of Pro led to the lack of α‐helical structure in SDS micelles, which may be correlated with weakened antimicrobial potency. This study indicated that Val/Arg‐rich peptides should have moderate net charge and Pro may play a role in reducing the toxicity against red blood cells.
Are foster children's schools of origin always best? School quality in birth vs. foster parent neighbourhoods
Authors: Fries Lauren , Klein Sacha , Ballantyne Molly
Published: March 2014

Research has documented that foster children have high rates of school mobility, and it is widely believed that this contributes to their poor educational outcomes. Recent US policies address this by attempting to minimize schools transfers for foster children; however, these policies have largely ignored the issue of school quality. The current study uses descriptive statistics and mixed factor analysis of variance to assess (i) the quality of schools attended by elementary‐aged US foster children living in a large, urban school district (n = 683); (ii) their rates of school mobility; and (iii) differences between the quality of schools located in their birth parent vs. foster placement neighbourhoods. Results indicate that these foster children were attending poor performing schools and had high rates of school transfers. For the sample as a whole and specifically for African‐Americans and Hispanics, schools located in placement neighbourhoods were higher performing than schools in birth parent neighbourhoods. For white children, however, birth parent schools outperformed placement schools. These findings highlight the importance of considering school quality, not just continuity, when making educational decisions for children in out‐of‐home care.
SATO: Surface Area Traversal Order for Shadow Ray Tracing
Authors: Nah Jae‐Ho , Manocha Dinesh
Published: March 2014

We present the surface area traversal order (SATO) metric to accelerate shadow ray traversal. Our formulation uses the surface area of each child node to compute the TO. In this metric, we give a traversal priority to the child node with the larger surface area to quickly find occluders. Our algorithm reduces the pre‐processing overhead significantly, and is much faster than other metrics. Overall, the SATO is useful for ray tracing large and complex dynamic scenes (e.g. a few million triangles) with shadows.