bluuebunny/crossref_metadata_2025 huggingface dataset:
Wireless data encoding and decoding using OAM modes
Authors: Allen B. , Tennant A. , Bai Qiang , Chatziantoniou E.
Published: January 2014

A means of encoding and decoding data using wireless orbital angular momentum (OAM) modes is proposed and analysed. Source data symbols are used to select an OAM mode, which is generated using an 8‐element circular array. A 2‐element array is used to detect the mode by estimating the phase gradient of the received signal, and hence identifying the transmitted data symbol. The results are presented in terms of mode estimation error.
Highly enhanced avalanche probability using sinusoidally-gated silicon avalanche photodiode
Authors: Suzuki Shingo , Namekata Naoto , Tsujino Kenji , Inoue Shuichiro
Published: January 2014

We report on visible light single photon detection using a sinusoidally-gated silicon avalanche photodiode. Detection efficiency of 70.6% was achieved at a wavelength of 520 nm when an electrically cooled silicon avalanche photodiode with a quantum efficiency of 72.4% was used, which implies that a photo-excited single charge carrier in a silicon avalanche photodiode can trigger a detectable avalanche (charge) signal with a probability of 97.6%.
Modelling of micro-Hall sensors for magnetization imaging
Authors: Manzin A. , Nabaei V.
Published: January 2014

This paper presents a numerical model for the study of micro-Hall magnetometry applications, aiming at evaluating the sensitivity of semiconductor miniaturized devices to the stray field of permalloy nanostructures with ring and disk geometry. The procedure couples a micromagnetic code, for the calculation of the stray field generated by the nanomagnet, to a 2D classical transport model for the determination of the electric potential distribution inside the Hall plate. The model is applied to study the sensitivity of a micro-Hall device in the detection of magnetization switching processes characterized by vortex state, focusing on the influence of magnetic nanostructure position.
Green's function for a spherical dielectric discontinuity and its application to simulation
Authors: Linse Per , Lue Leo
Published: January 2014

We present rapidly convergent expressions for the Green's function of the Poisson equation for spherically symmetric systems where the dielectric constant varies discontinuously in the radial direction. These expressions are used in Monte Carlo simulations of various electrolyte systems, and their efficiency is assessed. With only the leading term of the expansion included, a precision of the polarization energy of 0.01 kJ mol−1 or better was achieved, which is smaller than the statistical uncertainty of a typical simulation. The inclusion of the dielectric inhomogeneity leads to a 2.5-fold increase of the computational effort, which is modest for this type of model. The simulations are performed on six types of systems having either (i) a uniform surface charge distribution, (ii) a uniform volume charge distribution, or (iii) mobile ions, which were neutralized by mobile counterions. The ion density distributions are investigated for different dielectric conditions. These spatial distributions are discussed in terms of the importance of (i) the direct mean-field Coulomb interaction, (ii) the surface charge polarization at the dielectric discontinuity, and/or (iii) the change in the attractive Coulomb correlations.
Distributed feedback gallium nitride nanowire lasers
Authors: Wright Jeremy B. , Campione Salvatore , Liu Sheng , Martinez Julio A. , Xu Huiwen , Luk Ting S. , Li Qiming , Wang George T. , Swartzentruber Brian S. , Lester Luke F. , Brener Igal
Published: January 2014

Achieving single-mode laser operation in nanowire lasers remains a challenge due to a lack of mode selection approaches. We have implemented single-mode lasing using distributed feedback by externally coupling gallium nitride nanowires to a dielectric grating to achieve mode-control. The effective periodicity of the grating experienced by the nanowire was altered using nanomanipulation to change the angular alignment between the nanowire and the grating. The effective periodicity controls the spectral location of the distributed feedback stop-band. Single-mode emission was achieved at an alignment, where the designed periodicity of the grating was experienced by the nanowire.
Design study of electron cyclotron resonance-ion plasma accelerator for heavy ion cancer therapy
Authors: Inoue T. , Hattori T. , Sugimoto S. , Sasai K.
Published: January 2014

Electron Cyclotron Resonance-Ion Plasma Accelerator (ECR-IPAC) device, which theoretically can accelerate multiple charged ions to several hundred MeV with short acceleration length, has been proposed. The acceleration mechanism is based on the combination of two physical principles, plasma electron ion adiabatic ejection (PLEIADE) and Gyromagnetic Autoresonance (GYRAC). In this study, we have designed the proof of principle machine ECR-IPAC device and simulated the electromagnetic field distribution generating in the resonance cavity. ECR-IPAC device consisted of three parts, ECR ion source section, GYRAC section, and PLEIADE section. ECR ion source section and PLEIADE section were designed using several multi-turn solenoid coils and sextupole magnets, and GYRAC section was designed using 10 turns coil. The structure of ECR-IPAC device was the cylindrical shape, and the total length was 1024 mm and the maximum diameter was 580 mm. The magnetic field distribution, which maintains the stable acceleration of plasma, was generated on the acceleration center axis throughout three sections. In addition, the electric field for efficient acceleration of electrons was generated in the resonance cavity by supplying microwave of 2.45 GHz.
Symmetry-adapted perturbation theory with Kohn-Sham orbitals using non-empirically tuned, long-range-corrected density functionals
Authors: Lao Ka Un , Herbert John M.
Published: January 2014

The performance of second-order symmetry-adapted perturbation theory (SAPT) calculations using Kohn-Sham (KS) orbitals is evaluated against benchmark results for intermolecular interactions. Unlike previous studies of this “SAPT(KS)” methodology, the present study uses non-empirically tuned long-range corrected (LRC) functionals for the monomers. The proper \documentclass[12pt]{minimal}\begin{document}$\mbox{v{}_{\rm xc}}(r)\rightarrow 0$\end{document}v xc (r)→0 asymptotic limit is achieved by tuning the range separation parameter in order to satisfy the condition that the highest occupied KS energy level equals minus the molecule's ionization energy, for each monomer unit. Tests for He2, Ne2, and the S22 and S66 data sets reveal that this condition is important for accurate prediction of the non-dispersion components of the energy, although errors in SAPT(KS) dispersion energies remain unacceptably large. In conjunction with an empirical dispersion potential, however, the SAPT(KS) method affords good results for S22 and S66, and also accurately predicts the whole potential energy curve for the sandwich isomer of the benzene dimer. Tuned LRC functionals represent an attractive alternative to other asymptotic corrections that have been employed in density-functional-based SAPT calculations, and we recommend the use of tuned LRC functionals in both coupled-perturbed SAPT(DFT) calculations and dispersion-corrected SAPT(KS) calculations.
Time-harmonic dynamic Green's functions for two-dimensional functionally graded magnetoelectroelastic materials
Authors: Wang Yi-Ze , Kuna Meinhard
Published: January 2014

In this study, for two-dimensional functionally graded magnetoelectroelastic materials, the explicit solutions of time-harmonic dynamic Green's functions are derived. With the coupling of the mechanical-electric-magnetic fields and material gradient properties of exponentially varying, the governing equations are presented. Different conditions on the wave number and material gradient characteristics are discussed, separately. In the numerical results, the effects of both dynamic and gradient properties on the Green's functions are presented. It is also found that the time-harmonic dynamic Green's functions tend to zero with the distance increasing.
Field-current phase diagrams of in-plane spin transfer torque memory cells with low effective magnetization storage layers
Authors: San Emeterio Alvarez L. , Lacoste B. , Rodmacq B. , Nistor L. E. , Pakala M. , Sousa R. C. , Dieny B.
Published: January 2014

Field-current phase diagrams were measured on in-plane anisotropy Co60Fe20B20 magnetic tunnel junctions to obtain the spin transfer torque (STT) field-current switching window. These measurements were used to characterise junctions with varying free layer thicknesses from 2.5 down to 1.1 nm having a reduced effective demagnetizing field due to the perpendicular magnetic anisotropy at CoFeB/MgO interface. Diagrams were obtained with 100 ns current pulses, of either same or alternating polarity. When consecutive pulses have the same polarity, it is possible to realize the STT switching even for conditions having a low switching probability. This was evidenced in diagrams with consecutive pulses of alternating polarity, with 100% switching obtained at 4.7 MA/cm2, compared to the lower 3.4 MA/cm2 value for same polarity pulses. Although the low level of the current density window is higher in alternating polarity diagrams, the field window in both diagrams is the same and therefore independent of the pulse polarity sequence.
Photodegradation of luminescence in organic-ligand-capped Eu3+:LaF3 nano-particles
Authors: King Gavin G. G. , Taylor Luke R. , Clarke David J. , Quilty J. W. , Longdell Jevon J.
Published: January 2014

The luminescence from europium doped lanthanum trifluoride (Eu3+:LaF3) nano-crystals can be greatly enhanced by capping with β-diketonate organic ligands. Here, we report on photo-stability measurements for the case of nano-crystals capped with thenoyltrifluroacetone (TTA) and compared with those capped with an inactive ligand, oleic acid. With exposure to UV pump light, we observed significant decrease in fluorescence and change in emission spectrum of the TTA-capped nano-particles whilst the fluorescence lifetime remained approximately constant. After a dose of order 70 kJ cm−2, the luminescence level was similar to that of oleic acid capped nano-crystals. We discuss possible mechanisms.
Optical isolation via unidirectional resonant photon tunneling
Authors: Moccia Massimo , Castaldi Giuseppe , Galdi Vincenzo , Alù Andrea , Engheta Nader
Published: January 2014

We show that tri-layer structures combining epsilon-negative and magneto-optical material layers can exhibit unidirectional resonant photon tunneling phenomena that can discriminate between circularly polarized (CP) waves of given handedness impinging from opposite directions, or between CP waves with different handedness impinging from the same direction. This physical principle, which can also be interpreted in terms of a Fabry-Perot-type resonance, may be utilized to design compact optical isolators for CP waves. Within this framework, we derive simple analytical conditions and design formulae, and quantitatively assess the isolation performance, also taking into account the unavoidable imperfections and nonidealities.
Influence of the carrier density in disordered organics with Gaussian density of states on organic field-effect transistors
Authors: Scheinert Susanne , Paasch Gernot
Published: January 2014

Transport states in disordered organic semiconductors are widely accepted to be Gaussian distributed with a rather narrow variance (width) of the order of roughly 100–150 meV. This is a result of intensive analysis of experimental data and theoretical work using different model assumptions on hopping transport. For this transport mechanism, the dependencies of the carrier mobility on temperature, carrier density, and field are described by analytical approximations, which can be implemented in advanced device simulation programs. However, also the carrier density itself is determined by the Gaussian density of states (GDOS) and the energy integral over the product of the GDOS and the Fermi distribution function can only be calculated numerically. But meanwhile the published [G. Paasch and S. Scheinert, J. Appl. Phys. 107, 104501 (2010)] analytical approximation for the charge carrier density of organics with GDOS is implemented in the Sentaurus Device simulator. We present here results of detailed numerical simulations of organic field-effect transistors applying this model. It turns out that an important parameter is the distance of the GDOS maximum from the band edge, which is not directly accessible from experiment since the measured DOS shows a much larger band width (the narrow transport GDOS might be the tail). Only for a special case, depending on the variance, the deviations from a non-degenerate inorganic semiconductor are rather small. Furthermore, the results are affected by the properties of the source/drain contacts (Ohmic or Schottky type). Inclusion of both the calculation of the carrier concentration assuming the GDOS and the dependence of the mobility on this concentration shows that the influence of the latter is much larger. Nevertheless, the deviations from simulations for an inorganic semiconductor show that the carrier density for the GDOS should be taken into account in device simulations.
Effect of substitution of In for Co on magnetostructural coupling and magnetocaloric effect in MnCo1-xInxGe compounds
Authors: Wu R. R. , Bao L. F. , Hu F. X. , Wang J. , Zheng X. Q. , Liu Y. , Sun J. R. , Shen B. G.
Published: January 2014

Effect of replacement of Co by In with larger atomic radius but fewer valence numbers on magnetostructural coupling and magnetocaloric effect is studied in MnCo1-xInxGe compounds. The substitution of Co by a small amount of In (1.5%–2%) can shift martensitic transformation Tstru to lower temperature and make it overlap with Curie temperature TC. As a result, magnetostructural coupling is created and large entropy change (ΔS) takes place. Further increasing In content to x = 0.03 leads to decoupling, but the martensitic transition (Tstru ∼ 249 K) is still close to the magnetic transition (TcA ∼ 269 K). As a result, two close ΔS peaks appear. Mechanism related to different large entropy change in the coupled and decoupled samples are discussed.
Infrared spectroscopy of large scale single layer graphene on self assembled organic monolayer
Authors: Woo Kim Nak , Youn Kim Joo , Lee Chul , Jin Kim Sang , Hee Hong Byung , Choi E. J.
Published: January 2014

We study the effect of self-assembled monolayer (SAM) organic molecule substrate on large scale single layer graphene using infrared transmission measurement on Graphene/SAM/SiO2/Si composite samples. From the Drude weight of the chemically inert CH3-SAM, the electron-donating NH2-SAM, and the SAM-less graphene, we determine the carrier density doped into graphene by the three sources—the SiO2 substrate, the gas-adsorption, and the functional group of the SAM's—separately. The SAM-treatment leads to the low carrier density N ∼ 4 × 1011 cm−2 by blocking the dominant SiO2- driven doping. The carrier scattering increases by the SAM-treatment rather than decreases. However, the transport mobility is nevertheless improved due to the reduced carrier doping.
Weak antilocalization and conductance fluctuation in a single crystalline Bi nanowire
Authors: Kim Jeongmin , Lee Seunghyun , Brovman Yuri M. , Kim MinGin , Kim Philip , Lee Wooyoung
Published: January 2014

We present the low temperature transport properties of an individual single-crystalline Bi nanowire grown by the on-film formation of nanowire method. The temperature dependent resistance and magnetoresistance of Bi nanowires were investigated. The phase coherence length was obtained from the fluctuation pattern of the magnetoresistance below 40 K using universal conductance fluctuation theory. The obtained temperature dependence of phase coherence length and the fluctuation amplitude indicates that the transport of electrons shows 2-dimensional characteristics originating from the surface states. The temperature dependence of the coherence length derived from the weak antilocalization effect using the Hikami–Larkin–Nagaoka model is consistent with that from the universal conductance fluctuations theory.
Trapping of electrons in troughs of self generated electromagnetic standing waves in a bounded plasma column
Authors: Bhattacharjee Sudeep , Dey Indranuj , Roy Chowdhury Krishanu , Sahu Debaprasad , Pandey Shail , Chatterjee Sanghomitro
Published: January 2014

Observations and measurements are reported on electron trapping in troughs of self-generated electromagnetic standing waves in a bounded plasma column confined in a minimum-B field. The boundaries are smaller than the free space wavelength of the waves. Earlier work of researchers primarily focused upon electron localization effects induced by purely electrostatic perturbation. We demonstrate the possibility in the presence of electromagnetic standing waves generated in the bounded plasma column. The electron trapping is verified with electrostatic measurements of the plasma floating potential, electromagnetic measurements of the wave field profile, and optical intensity measurements of Argon ionic line at 488 nm. The experimental results show a reasonably good agreement with predictions of a Monte Carlo simulation code that takes into account all kinematical and dynamical effects in the plasma in the presence of bounded waves and external fields.
Excess carrier generation in femtosecond-laser processed sulfur doped silicon by means of sub-bandgap illumination
Authors: Guenther Kay-Michael , Gimpel Thomas , Tomm Jens W. , Winter Stefan , Ruibys Augustinas , Kontermann Stefan , Schade Wolfgang
Published: January 2014

With Fourier-transform photocurrent spectroscopy and spectral response measurements, we show that silicon doped with sulfur by femtosecond laser irradiation generates excess carriers, when illuminated with infrared light above 1100 nm. Three distinct sub-bandgap photocurrent features are observed. Their onset energies are in good agreement with the known sulfur levels S+, S0, and S20. The excess carriers are separated by a pn-junction to form a significant photocurrent. Therefore, this material likely demonstrates the impurity band photovoltaic effect.
Amodal Completion as Reflected by Gaze Durations
Authors: Plomp Gijs , Nakatani Chie , Bonnardel Valérie , van Leeuwen Cees
Published: January 2014

In two experiments amodal completion of partly occluded shapes was investigated by recording eye movements in a directed visual-search task. Participants searched arrays of shapes in a prescribed order for target figures that could partly be occluded. Longer gaze durations were found on occlusion patterns than on truncated control patterns for targets but not for non-targets. This effect of occlusion was restricted to a subset of the stimuli. A second experiment was carried out to establish whether this restriction resulted from structural properties of the stimuli or their familiarity. Occlusion patterns in this experiment were ambiguous with respect to structure, allowing both local and global completions. One of the completions was always less familiar than the other. The results showed longer gazes only for the less familiar completions, irrespective of whether they were local or global.
Formation and HERON Reactivity of Cyclic N,N-Dialkoxyamides
Authors: Glover Stephen A. , Rosser Adam A. , Taherpour Avat (Arman) , Greatrex Ben W.
Published: January 2014

Cyclic N,N-dialkoxyamides have been made, for the first time, by hypervalent iodine oxidation of β- and γ-hydroxyhydroxamic esters 17, 19, and 21. The fused γ-lactam products, N-butoxy- and N-benzyloxybenzisoxazolones (22a and 22b), are stable while alicyclic γ-lactam and δ-lactam products, 24 and 25, although observable by NMR spectroscopy and ESI-MS are unstable at room temperature, undergoing HERON reactions. The γ-lactam 24 undergoes exclusive ring opening to give a butyl ester-functionalised alkoxynitrene 28. The δ-lactam 25, instead, undergoes a HERON ring contraction to give butyrolactone (27). The structures of model γ- and δ-lactams 6, 7, and 8 have been determined at the B3LYP/6-31G(d) level of theory and the γ-lactams are much more twisted than the acyclic N,N-dimethoxyacetamide (5) resulting in a computed amidicity for 6 of only 25 % that of N,N-dimethylacetamide (3). The HERON reactions of N,N-dimethoxyacetamide (5) and alicyclic models 6 and 8 have been modelled computationally. The facile ring opening of 6 (EA = 113 kJ mol–1) and ring contraction of 8 (EA = 145 kJ mol–1) are predicted well, when compared with the HERON rearrangement of 5 (EA = 178 kJ mol–1).
Assessment of phloem mobility of xenobiotics in Triticum aestivum and Brachypodium distachyon
Authors: Zhivotovsky Castello Olena , Bowling Andrew J. , Deboer Gerrit , Adelfinskaya Yelena
Published: January 2014

Due to evolved resistance and environmental regulations, there is a particular need in the agricultural market for a new graminicide. An essential requirement of a novel, foliar applied graminicide is sufficient phloem mobility in the plant to reach meristematic tissues for the expression of activity leading to the desired control of unwanted vegetative growth. A robust and reliable phloem bioassay utilising a monocot species is highly desirable for early stage experimental compounds. Vascular tissues and translocation patterns of organic compounds in purple false brome (Brachypodium distachyon L. P. Beauv.), a model organism for temperate grasses, were studied and compared with those of wheat (Triticum aestivum L.). Microscopic studies with tracer dyes were used to determine if B. distachyon has a xylem discontinuity between the developing seed and the rachilla xylem, the same as found in T. aestivum. Based on 14C-radiolabelled and non-radiolabelled studies using known xylem and phloem mobile pesticidal compounds, there was a significant difference in the amount of the xylem mobile compounds in the chaff and stem as compared with the phloem mobile compounds found in the grain. The findings described in this report show a clear evidence of xylem discontinuity in B. distachyon, and provide a novel system for a rapid screening of phloem mobility of herbicides in monocot species.
Is the differential response of riparian plant performance to extreme drought and inundation events related to differences in intraspecific trait variation?
Authors: van der Knaap Yasmijn A. M. , Aerts Rien , van Bodegom Peter M.
Published: January 2014

Previous research on the impacts of extreme events has focussed mainly on plant performance. Selective effects of extremes suggests that appropriate traits to withstand extremes, or the ability to modulate traits, may increase the competitive advantage and survival of a species. We tested how multiple extreme events affect riparian plant performance, and whether this relates to intraspecific trait variation. We hypothesised that species tolerant to extreme environmental conditions would show highest intraspecific trait variation. We conducted a greenhouse experiment where 25 wet to drought-tolerant species (grasses and herbs) were subjected to single and double 10 day drought and inundation events, and all combinations thereof. We measured plant performance and multiple traits. Performance was severely reduced, with clear synergistic, non-additive effects of extreme events. Adverse effects were stronger for wet-tolerant than drought-tolerant species and for grasses than herbs. Three traits were identified as predictors of species responses to extremes. Despite known trait variation for these species, no variation occurred under these conditions, indicating that responses are difficult to explain from impacts of mean environmental conditions. Our results indicate that multiple events may lead to quantitatively different impacts than single events, which hampers predicting plant response to a future climate.
Shotgun proteomics of rainbow trout ovarian fluid
Authors: Nynca Joanna , Arnold Georg J. , Fröhlich Thomas , Ciereszko Andrzej
Published: January 2014

In the present study we used a shotgun proteomic approach to identify 54 proteins of rainbow trout ovarian fluid. The study has unravelled the identity of several proteins not previously reported in fish ovarian fluid. The proteome of trout ovarian fluid consists of diverse proteins participating in lipid binding and metabolism, carbohydrate and ion transport, innate immunity, maturation and ovulation processes. Most trout ovarian fluid proteins correspond to follicular fluid proteins of higher vertebrates, but 15% of the proteins were found to be different, such as those related to the immune system (precerebellin-like protein), proteolysis (myeloid cell lineage chitinase), carbohydrate and lipid binding and metabolism (vitellogenins), cell structure and shape (vitelline envelope protein gamma) and a protein with unknown functions (UPF0762 protein C6orf58 homologue). The present study could help in the decoding of the biological function of these proteins and in the discovery of potential biomarkers of oocyte quality.
Assessing mucociliary transport of single particles in vivo shows variable speed and preference for the ventral trachea in newborn pigs
Authors: Hoegger Mark J. , Awadalla Maged , Namati Eman , Itani Omar A. , Fischer Anthony J. , Tucker Alexander J. , Adam Ryan J. , McLennan Geoffrey , Hoffman Eric A. , Stoltz David A. , Welsh Michael J.
Published: January 2014

Significance

Mucociliary transport (MCT) defends lungs by removing particulates, and defective MCT is hypothesized to contribute to the onset of lung diseases such as asthma, chronic bronchitis, and cystic fibrosis. However, testing those hypotheses has been limited by current MCT assays and mouse models of human disease. We developed an in vivo MCT assay in newborn pigs, which share physiological and anatomical features with humans. The X-ray–computed tomographic-based method provided high spatial and temporal resolution. We discovered that particles preferentially travel up the ventral airway surface. We also discovered substantial heterogeneity in rates of individual particle movement, indicating that MCT does not likely involve homogeneous mucus blankets. The granularity of the data may aid understanding of MCT and disease pathogenesis.
Continued Emergence of USA300 Methicillin-ResistantStaphylococcus aureusin the United States: Results from a Nationwide Surveillance Study
Authors: Diekema Daniel J. , Richter Sandra S. , Heilmann Kristopher P. , Dohrn Cassie L. , Riahi Fathollah , Tendolkar Shailesh , McDanel Jennifer S. , Doern Gary V.
Published: January 2014

Background.

The epidemiology of methicillin-resistantStaphylococcus aureus(MRSA) is changing, with USA300 emerging first in community and then in healthcare settings. We performed nationwide surveillance to assess recent trends in the molecular epidemiology of MRSA.

Methods.

One hundred consecutive unique clinically significantS. aureusisolates were recovered from patients at each of 43 US centers between July 1, 2011, and December 31, 2011. Susceptibility testing, pulsed-field gel electrophoresis (PFGE), staphylococcal protein A gene (spa) and staphylococcal cassette chromosome mec typing, and Panton-Valentine leukocidin detection were performed on all MRSA isolates.

Results.

Of 4,131 isolates collected, 2,093 (51%) were MRSA. Specimen sources of MRSA isolates included wound or abscess (54%), blood (24%), lower respiratory tract (11%), and other sterile site (10%). Thirty percent were isolated more than 48 hours after hospital admission (ie, were associated with nosocomial acquisition of infection). USA300 was the most common PFGE type (1,269 isolates; 61%), overall and in all regions, followed by USA100 (368 isolates; 18%). Among 173spatypes found, the most common were t008 (51%) and t002 (18%); no otherspatype accounted for more than 2% of isolates. One strain type (USA300/t008/IV) constituted almost half of all MRSA isolates (1,005 isolates; 48%) and was the most common at all body sites, causing 37% of MRSA bloodstream infections (BSIs) and 38% of nosocomial MRSA infections. Multidrug-resistant phenotypes were found among 34 USA300 isolates (3%) from 18 states.

Conclusions.

The USA300 PFGE type continues to advance nationwide. A single strain type (USA300/t008/IV) predominates in all regions and infection sites and is now more common than USA 100 as a cause of MRSA BSI and nosocomial infections. Although most USA300 retain typical susceptibility profiles, multidrug-resistant phenotypes are emerging.
Sendov conjecture for high degree polynomials
Authors: Dégot Jérôme
Published: January 2014

Sendov’s conjecture says that if all zeros of a complex polynomialPPlie in the closed unit disk andaadenotes one of them, then the closed disk of centeraaand radius11contains a critical point ofPP(i.e. a zero of its derivativeP′P’). The main result of this paper is to prove that, for eachaa, there exists an integerNNsuch that the disk|ζ−a|≤1|\zeta - a|\leq 1contains a critical point ofPPwhen the degree ofPPis larger thanNN. We obtain this by studying the geometry of the zeros and critical points of a polynomial which would eventually contradict Sendov’s conjecture.
First Report of QOI-insensitive Powdery Mildew (Erysiphe polygoni) on Sugar Beet in the United States
Authors: Bolton M. D. , Neher O. T.
Published: January 2014

The $2.1 billion United States sugar beet (Beta vulgaris L.) industry is the primary provider of domestic sucrose. Sugar beet powdery mildew is caused by Erysiphe polygoni DC and occurs principally in sugar beet growing regions in the western United States. In these regions, the quinone outside inhibitor (QOI) fungicides pyraclostrobin (Headline, BASF, NC) and trifloxystrobin (Gem, Bayer Crop Science, NC) have been important tools to manage powdery mildew since registration in 2002 and 2005, respectively. However, researchers in Idaho reported poor disease management despite QOI application starting in 2011. In 2013, a research plot near Parma, ID, containing natural powdery mildew infection received treatments of pyraclostrobin, trifloxystrobin, or was untreated (control). Since there was no significant reduction in disease levels between QOI-treated blocks and untreated control blocks, experiments were conducted to clone a partial fragment of the E. polygoni cytochrome b (cytb) gene to gain insight into the molecular basis of QOI resistance in this pathosystem. The primers MDB-920 (5′-CACATCGGAAGAGGTTTATA-3′) and MDB-922 (5′-GGTATAGATCTTAATATAGCATAG-3′) were designed based on consensus sequences of several fungal cytb genes obtained from GenBank (data not presented) and used to amplify a 575-bp fragment of the E. polygoni cytb gene using DNA isolated from 12 infected leaf samples collected in September 2013 from the Parma research plot. Each sample consisted of three leaves harvested from three plants (one leaf per plant) in an experimental block. All DNA extraction, PCR, and sequencing procedures were as described previously (1). PCR products derived from six QOI-treated samples and six untreated samples were sequenced directly. Without exception, all QOI-treated samples harbored a point mutation at nucleotide position 143 that encoded a G143A mutation compared with cytb sequence from untreated samples. The two identified cytb haplotypes have been deposited in GenBank under accession numbers KF925325 and KF925326. This is the first report of QOI resistance and the associated cytb G143A mutation in E. polygoni. The G143A mutation has been reported in most QOI-resistant pathogens to date (2). When the G143A mutation dominates in a pathogen population, there is a consistent association with a loss of disease management despite QOI application (3). Careful monitoring and judicious use of QOI fungicides will be necessary to ensure QOI fungicides remain efficacious for sugar beet powdery mildew management in the United States.

References: (1) M. D. Bolton et al. Pest Manag. Sci. 69:35, 2013. (2) N. Fisher and B. Meunier. FEMS Yeast Res. 8:183, 2008. (3) U. Gisi et al. Pest Manag. Sci. 58:859, 2002.
Genetic Diversity and Population Structure of Fusicladium effusum on Pecan in the United States
Authors: Bock C. H. , Wood B. W. , Stevenson K. L. , Arias R. S.
Published: January 2014

Fusicladium effusum causes pecan scab, which is the most destructive disease of pecan orchards in the United States. Conidia of the pathogen are spread by rain splash and wind. The fungus is pathogenically diverse; yet there is no information on its genetic diversity or population genetics. Universally primed polymerase chain reaction (UP-PCR) was used to investigate the genetic diversity and population structure on a hierarchical sample of 194 isolates collected from 11 orchard locations from Florida to Texas, consisting of three to four isolates from each of five to six trees at each location. Genetic variation was high throughout the region, with all but nine of the multilocus haplotypes being unique. Nei's average gene diversity ranged from 0.083 for a population from Mississippi to 0.160 for a population from Kansas. An analysis of molecular variance of the hierarchically sampled populations found that the majority of the genetic variability (82.6%) occurred at the scale of the individual tree and only relatively small amounts among populations in trees from an orchard (5.0%) or within groups (i.e., orchard location populations) (12.5%). The results suggest little population differentiation in F. effusum in the southeastern United States, although φpt values of genetic distance for pairwise comparisons indicated some populations could be differentiated from others. There was evidence of linkage disequilibrium in certain populations, and the common occurrence of asexual reproduction in F. effusum could lead to measurable linkage disequilibrium under certain circumstances. However, the degree of genetic diversity and the scale over which diversity is distributed is evidence that F. effusum undergoes regular recombination despite no known sexual stage.
Clonal Expansion of Verticillium dahliae in Lettuce
Authors: Gurung S. , Short D. P. G. , Atallah Z. K. , Subbarao K. V.
Published: January 2014

Few studies in population biology have documented how structure and diversity of pathogens evolve over time at local scales. With the historical samples of Verticillium dahliae available from lettuce, we investigated the structure and diversity of this pathogen in time and space. Three hundred twenty-nine V. dahliae isolates from lettuce fields collected over 18 years were characterized with polymorphic microsatellite markers and polymerase chain reaction tests for race and mating type. Genetic variation within and among commercial lettuce fields in a single season was also investigated using an additional 146 isolates. Sixty-two haplotypes (HTs) were observed among the 329 isolates. A single HT was frequently observed over multiple years and locations (61.40%). Genetic diversity, allelic richness, and private allelic richness suggested a relatively recent clonal expansion. Race 1 (93.63%) and MAT1-2-1 (99.69%) were overwhelmingly represented among the isolates. Linkage disequilibrium was significant (P < 0.001) for all populations, suggesting limited sexual recombination in the sampled populations from lettuce. Populations from 2006, 2009, and 2010 had higher numbers of unique HTs, implying a recent introduction of novel HTs. We conclude that V. dahliae population from lettuce evaluated in this study is expanding clonally, consistent with an asexually reproducing pathogen, and the movement of clonal genotypes locally occurs over time.
Minimally Invasive Segmental Artery Coil Embolization for Preconditioning of the Spinal Cord Collateral Network before One-Stage Descending and Thoracoabdominal Aneurysm Repair
Authors: Luehr Maximilian , Salameh Aida , Haunschild Josephina , Hoyer Alexandro , Girrbach Felix F. , von Aspern Konstantin , Dhein Stefan , Mohr Friedrich-Wilhelm , Etz Christian D.
Published: January 2014

Objective

Paraplegia remains the most devastating complication after thoracic and thoracoabdominal aortic aneurysm (TAA/A) repair. The collateral network (CN) concept of spinal cord perfusion suggests segmental artery (SA) occlusion to mobilize redundant intraspinal and paraspinal arterial sources and ultimately trigger arteriogenesis, leading to spinal cord blood flow restoration within 96 to 120 hours. This principle is used by the two-staged approach to TAA/A-repair—which has lead to an elimination of paraplegia in an experimental model. However, the clinical implementation of a two-staged surgical procedure is challenging, particularly in the absence of an appropriate vascular segment for a “staged” open anastomosis or an appropriate endovascular landing zone. Selective, transfemoral minimally invasive SA coil embolization (MISACE) could provide the solution for one-stage repair of extensive aortic pathologies by triggering arteriogenic CN preconditioning and thereby allowing for recruitment of otherwise redundant arterial collaterals to the spinal cord.

Methods

The feasibility of MISACE was explored in a single animal using an established piglet model. A 6F sheet was introduced via the femoral artery, and a 4F standard Judkins catheter was used for selective angiography and coil insertion. All thoracic and lumbar aortic SAs (15 pairs; Th4–L5) were successfully identified by dye injection. Pediatric platinum endovascular coils (Trufill Pushable Coils, 3 × 20 mm; Cordis, Waterloo, Belgium) were deployed to serially occlude the SA mimicking a CN preconditioning procedure.

Results

All intercostal (thoracic) and lumbar aortic SAs (Th4–L5) were successfully identified and occluded by coil embolization. Successful SA coil embolization was verified intraoperatively by selective dye injection on angiography. No intraoperative coil dislodgement occurred. Autopsy revealed complete occlusion of all embolized SAs enhanced by early local thrombus formation. Thrombotic material was found only distally to the coils. No SA dissection was observed at the aortic SA origins.

Conclusions

The MIS ACE technique allows for rapid serial endovascular occlusion of all thoracic and lumbar SAs. This new innovative approach bares the potential to CN preconditioning at the respective level of aortic pathology—to allow for adequate perioperative spinal cord blood supply—before conventional open or endovascular surgery. Selective, transarterial MISACE might lead to a dramatic reduction of ischemic spinal cord injury after open and endovascular TAA/A repair in the future.
Hidden altruism in a real-world setting
Authors: Raihani N. J.
Published: January 2014

Concerns for reputation can promote cooperative behaviour. Individuals that behave cooperatively stand to benefit if they gain in influence, status or are more likely to be chosen as interaction partners by others. Most theoretical and empirical models of cooperation predict that image score will increase with cooperative contributions. Individuals are therefore expected to make higher contributions when observed by others and should opt to make contributions publicly rather than privately, particularly when contributions are higher than average. Here, however, I find the opposite effect. Using data from an online fundraising website, I show that donors are more likely to opt for anonymity when making extremely low and extremely high donations. Mid-range donations, on the other hand, are typically publicized. Recent work has shown that extremely generous individuals may be ostracized or punished by group members. The data presented here suggest that individuals may hide high donations to avoid these repercussions.
Sir Maurice Vincent Wilkes. 26 June 1913 — 29 November 2010
Authors: Campbell-Kelly Martin
Published: January 2014

Maurice Wilkes was head of the Mathematical Laboratory (later Computer Laboratory) at Cambridge University from 1945 until his retirement in 1980. He led the construction of the EDSAC (Electronic Delay Storage Automatic Calculator), the world’s first practical stored-program computer, completed in May 1949. In 1951 he invented microprogramming, a fundamental technique of computer design. He subsequently led the construction of the EDSAC 2 and the Titan computers; he then established the CAP computer project, the Cambridge Digital Ring, and the Cambridge Distributed Computer System. Beyond Cambridge University, he was founding president of the British Computer Society. He was knighted in 2000 for services to computing.
Novel biological strategies for treatment of wear particle-induced periprosthetic osteolysis of orthopaedic implants for joint replacement
Authors: Goodman S. B. , Gibon E. , Pajarinen J. , Lin T.-H. , Keeney M. , Ren P.-G. , Nich C. , Yao Z. , Egashira K. , Yang F. , Konttinen Y. T.
Published: January 2014

Wear particles and by-products from joint replacements and other orthopaedic implants may result in a local chronic inflammatory and foreign body reaction. This may lead to persistent synovitis resulting in joint pain and swelling, periprosthetic osteolysis, implant loosening and pathologic fracture. Strategies to modulate the adverse effects of wear debris may improve the function and longevity of joint replacements and other orthopaedic implants, potentially delaying or avoiding complex revision surgical procedures. Three novel biological strategies to mitigate the chronic inflammatory reaction to orthopaedic wear particles are reported. These include (i) interference with systemic macrophage trafficking to the local implant site, (ii) modulation of macrophages from an M1 (pro-inflammatory) to an M2 (anti-inflammatory, pro-tissue healing) phenotype in the periprosthetic tissues, and (iii) local inhibition of the transcription factor nuclear factor kappa B (NF-κB) by delivery of an NF-κB decoy oligodeoxynucleotide, thereby interfering with the production of pro-inflammatory mediators. These three approaches have been shown to be viable strategies for mitigating the undesirable effects of wear particles in preclinical studies. Targeted local delivery of specific biologics may potentially extend the lifetime of orthopaedic implants.
Radiative energy budget reveals high photosynthetic efficiency in symbiont-bearing corals
Authors: Brodersen Kasper Elgetti , Lichtenberg Mads , Ralph Peter J. , Kühl Michael , Wangpraseurt Daniel
Published: January 2014

The light field on coral reefs varies in intensity and spectral composition, and is the key regulating factor for phototrophic reef organisms, for example scleractinian corals harbouring microalgal symbionts. However, the actual efficiency of light utilization in corals and the mechanisms affecting the radiative energy budget of corals are underexplored. We present the first balanced light energy budget for a symbiont-bearing coral based on a fine-scale study of the microenvironmental photobiology of the massive coral
Montastrea curta
. The majority (more than 96%) of the absorbed light energy was dissipated as heat, whereas the proportion of the absorbed light energy used in photosynthesis was approximately 4.0% under an irradiance of 640 µmol photons m
−2
s
−1
. With increasing irradiance, the proportion of heat dissipation increased at the expense of photosynthesis. Despite such low energy efficiency, we found a high photosynthetic efficiency of the microalgal symbionts showing high gross photosynthesis rates and quantum efficiencies (QEs) of approximately 0.1 O
2
photon
−1
approaching theoretical limits under moderate irradiance levels. Corals thus appear as highly efficient light collectors with optical properties enabling light distribution over the corallite/tissue microstructural canopy that enables a high photosynthetic QE of their photosynthetic microalgae
in hospite
.
Unlocking the secrets of multi-flagellated propulsion: drawing insights fromTritrichomonas foetus
Authors: Lenaghan Scott C. , Nwandu-Vincent Stefan , Reese Benjamin E. , Zhang Mingjun
Published: January 2014

In this work, a high-speed imaging platform and a resistive force theory (RFT) based model were applied to investigate multi-flagellated propulsion, usingTritrichomonas foetusas an example. We discovered thatT. foetushas distinct flagellar beating motions for linear swimming and turning, similar to the ‘run and tumble’ strategies observed in bacteria andChlamydomonas. Quantitative analysis of the motion of each flagellum was achieved by determining the average flagella beat motion for both linear swimming and turning, and using the velocity of the flagella as inputs into the RFT model. The experimental approach was used to calculate the curvature along the length of the flagella throughout each stroke. It was found that the curvatures of the anterior flagella do not decrease monotonically along their lengths, confirming the ciliary waveform of these flagella. Further, the stiffness of the flagella was experimentally measured using nanoindentation, allowing for calculation of the flexural rigidity ofT. foetus's flagella, 1.55×10−21N m2. Finally, using the RFT model, it was discovered that the propulsive force ofT. foetuswas similar to that of sperm andChlamydomonas, indicating that multi-flagellated propulsion does not necessarily contribute to greater thrust generation, and may have evolved for greater manoeuvrability or sensing. The results from this study have demonstrated the highly coordinated nature of multi-flagellated propulsion and have provided significant insights into the biology ofT. foetus.
Testing optimal foraging theory in a penguin–krill system
Authors: Watanabe Yuuki Y. , Ito Motohiro , Takahashi Akinori
Published: January 2014

Food is heterogeneously distributed in nature, and understanding how animals search for and exploit food patches is a fundamental challenge in ecology. The classic marginal value theorem (MVT) formulates optimal patch residence time in response to patch quality. The MVT was generally proved in controlled animal experiments; however, owing to the technical difficulties in recording foraging behaviour in the wild, it has been inadequately examined in natural predator–prey systems, especially those in the three-dimensional marine environment. Using animal-borne accelerometers and video cameras, we collected a rare dataset in which the behaviour of a marine predator (penguin) was recorded simultaneously with the capture timings of mobile, patchily distributed prey (krill). We provide qualitative support for the MVT by showing that (i) krill capture rate diminished with time in each dive, as assumed in the MVT, and (ii) dive duration (or patch residence time, controlled for dive depth) increased with short-term, dive-scale krill capture rate, but decreased with long-term, bout-scale krill capture rate, as predicted from the MVT. Our results demonstrate that a single environmental factor (i.e. patch quality) can have opposite effects on animal behaviour depending on the time scale, emphasizing the importance of multi-scale approaches in understanding complex foraging strategies.
Metabolic ‘engines’ of flight drive genome size reduction in birds
Authors: Wright Natalie A. , Gregory T. Ryan , Witt Christopher C.
Published: January 2014

The tendency for flying organisms to possess small genomes has been interpreted as evidence of natural selection acting on the physical size of the genome. Nonetheless, the flight–genome link and its mechanistic basis have yet to be well established by comparative studies within a volant clade. Is there a particular functional aspect of flight such as brisk metabolism, lift production or maneuverability that impinges on the physical genome? We measured genome sizes, wing dimensions and heart, flight muscle and body masses from a phylogenetically diverse set of bird species. In phylogenetically controlled analyses, we found that genome size was negatively correlated with relative flight muscle size and heart index (i.e. ratio of heart to body mass), but positively correlated with body mass and wing loading. The proportional masses of the flight muscles and heart were the most important parameters explaining variation in genome size in multivariate models. Hence, the metabolic intensity of powered flight appears to have driven genome size reduction in birds.