Molecular modeling of human neutral sphingomyelinase provides insight into its molecular interactions.

Science.gov (United States)

Dinesh; Goswami, Angshumala; Suresh, Panneer Selvam; Thirunavukkarasu, Chinnasamy; Weiergräber, Oliver H; Kumar, Muthuvel Suresh

2011-01-01

The neutral sphingomyelinase (N-SMase) is considered a major candidate for mediating the stress-induced production of ceramide, and it plays an important role in cell-cycle arrest, apoptosis, inflammation, and eukaryotic stress responses. Recent studies have identified a small region at the very N-terminus of the 55 kDa tumour necrosis factor receptor (TNF-R55), designated the neutral sphingomyelinase activating domain (NSD) that is responsible for the TNF-induced activation of N-SMase. There is no direct association between TNF-R55 NSD and N-SMase; instead, a protein named factor associated with N-SMase activation (FAN) has been reported to couple the TNF-R55 NSD to N-SMase. Since the three-dimensional fold of N-SMase is still unknown, we have modeled the structure using the protein fold recognition and threading method. Moreover, we propose models for the TNF-R55 NSD as well as the FAN protein in order to study the structural basis of N-SMase activation and regulation. Protein-protein interaction studies suggest that FAN is crucially involved in mediating TNF-induced activation of the N-SMase pathway, which in turn regulates mitogenic and proinflammatory responses. Inhibition of N-SMase may lead to reduction of ceramide levels and hence may provide a novel therapeutic strategy for inflammation and autoimmune diseases. Molecular dynamics (MD) simulations were performed to check the stability of the predicted model and protein-protein complex; indeed, stable RMS deviations were obtained throughout the simulation. Furthermore, in silico docking of low molecular mass ligands into the active site of N-SMase suggests that His135, Glu48, Asp177, and Asn179 residues play crucial roles in this interaction. Based on our results, these ligands are proposed to be potent and selective N-SMase inhibitors, which may ultimately prove useful as lead compounds for drug development.

Charge-Neutral Constant pH Molecular Dynamics Simulations Using a Parsimonious Proton Buffer.

Science.gov (United States)

Donnini, Serena; Ullmann, R Thomas; Groenhof, Gerrit; Grubmüller, Helmut

2016-03-08

In constant pH molecular dynamics simulations, the protonation states of titratable sites can respond to changes of the pH and of their electrostatic environment. Consequently, the number of protons bound to the biomolecule, and therefore the overall charge of the system, fluctuates during the simulation. To avoid artifacts associated with a non-neutral simulation system, we introduce an approach to maintain neutrality of the simulation box in constant pH molecular dynamics simulations, while maintaining an accurate description of all protonation fluctuations. Specifically, we introduce a proton buffer that, like a buffer in experiment, can exchange protons with the biomolecule enabling its charge to fluctuate. To keep the total charge of the system constant, the uptake and release of protons by the buffer are coupled to the titration of the biomolecule with a constraint. We find that, because the fluctuation of the total charge (number of protons) of a typical biomolecule is much smaller than the number of titratable sites of the biomolecule, the number of buffer sites required to maintain overall charge neutrality without compromising the charge fluctuations of the biomolecule, is typically much smaller than the number of titratable sites, implying markedly enhanced simulation and sampling efficiency.

Crystal Structure Analysis of Electromagnetic Wave Absorber Material BaFe12-xTix/2Znx/2O19Based

Science.gov (United States)

Delina, M.; Nenni, N.; Adi, W. A.

2018-04-01

The optimization of BaFe12-xTix/2Znx/2O19 (x=2.2; 2.4; 2.6; 2.8)single phase composition have been performed. The materials were synthesized by solid state reaction method through mechanical milling technique.The materials were made from the mixture of oxide materials, which are BaCO3, Fe2O3, TiO2 and ZnO. The mixture was milled for five hours using a High Energy Milling (HEM), was dried at 100°C in the Oven and then was sintered at 1000°C for five hours in the Furnace. The phase identification of BaFe12-xTix/2Znx/2O19 (x=2.2; 2.4; 2.6; 2.8) were carried out by using a Match Program while the crystal structure analysis were investigated by using a General Structure Analysis System (GSAS) program. The refinement results of x-ray diffraction pattern showed that the sample of x ≤ 2.4 have a BaFe12O19 single phase while the sample of x> 2.4 have two phases, which are BaFe12O19 and ZnFe2O4 phases. The surface morphology of sample and the element of sample were identified through an analysis of Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) data.

The nearly neutral and selection theories of molecular evolution under the fisher geometrical framework: substitution rate, population size, and complexity.

Science.gov (United States)

Razeto-Barry, Pablo; Díaz, Javier; Vásquez, Rodrigo A

2012-06-01

The general theories of molecular evolution depend on relatively arbitrary assumptions about the relative distribution and rate of advantageous, deleterious, neutral, and nearly neutral mutations. The Fisher geometrical model (FGM) has been used to make distributions of mutations biologically interpretable. We explored an FGM-based molecular model to represent molecular evolutionary processes typically studied by nearly neutral and selection models, but in which distributions and relative rates of mutations with different selection coefficients are a consequence of biologically interpretable parameters, such as the average size of the phenotypic effect of mutations and the number of traits (complexity) of organisms. A variant of the FGM-based model that we called the static regime (SR) represents evolution as a nearly neutral process in which substitution rates are determined by a dynamic substitution process in which the population's phenotype remains around a suboptimum equilibrium fitness produced by a balance between slightly deleterious and slightly advantageous compensatory substitutions. As in previous nearly neutral models, the SR predicts a negative relationship between molecular evolutionary rate and population size; however, SR does not have the unrealistic properties of previous nearly neutral models such as the narrow window of selection strengths in which they work. In addition, the SR suggests that compensatory mutations cannot explain the high rate of fixations driven by positive selection currently found in DNA sequences, contrary to what has been previously suggested. We also developed a generalization of SR in which the optimum phenotype can change stochastically due to environmental or physiological shifts, which we called the variable regime (VR). VR models evolution as an interplay between adaptive processes and nearly neutral steady-state processes. When strong environmental fluctuations are incorporated, the process becomes a selection model

Electron-impact dissociation of molecular hydrogen into neutral fragments

Science.gov (United States)

Scarlett, Liam H.; Tapley, Jonathan K.; Fursa, Dmitry V.; Zammit, Mark C.; Savage, Jeremy S.; Bray, Igor

2018-02-01

We present convergent close-coupling calculations of electron-impact dissociation of the ground state of molecular hydrogen into neutral fragments over the range of impact energies from 6 to 300 eV. The calculations account for dissociative excitation, excitation radiative decay dissociation, and predissociation through all bound electronic triplet states, and singlet states up to the D' 1 Π u state. An estimate is given for the contribution from the remaining bound electronic singlet states. Our results are in agreement with the recommended data of Yoon et al. [J. Phys. Chem. Ref. Data 37, 913 (2008)] in the low (6-12 eV) and high (60-70 eV) energy regions, but somewhat lower at the intermediate energies.

Molecular evolution of broadly neutralizing Llama antibodies to the CD4-binding site of HIV-1.

Science.gov (United States)

McCoy, Laura E; Rutten, Lucy; Frampton, Dan; Anderson, Ian; Granger, Luke; Bashford-Rogers, Rachael; Dekkers, Gillian; Strokappe, Nika M; Seaman, Michael S; Koh, Willie; Grippo, Vanina; Kliche, Alexander; Verrips, Theo; Kellam, Paul; Fassati, Ariberto; Weiss, Robin A

2014-12-01

To date, no immunization of humans or animals has elicited broadly neutralizing sera able to prevent HIV-1 transmission; however, elicitation of broad and potent heavy chain only antibodies (HCAb) has previously been reported in llamas. In this study, the anti-HIV immune responses in immunized llamas were studied via deep sequencing analysis using broadly neutralizing monoclonal HCAbs as a guides. Distinct neutralizing antibody lineages were identified in each animal, including two defined by novel antibodies (as variable regions called VHH) identified by robotic screening of over 6000 clones. The combined application of five VHH against viruses from clades A, B, C and CRF_AG resulted in neutralization as potent as any of the VHH individually and a predicted 100% coverage with a median IC50 of 0.17 µg/ml for the panel of 60 viruses tested. Molecular analysis of the VHH repertoires of two sets of immunized animals showed that each neutralizing lineage was only observed following immunization, demonstrating that they were elicited de novo. Our results show that immunization can induce potent and broadly neutralizing antibodies in llamas with features similar to human antibodies and provide a framework to analyze the effectiveness of immunization protocols.

Synthesis of a Neutral Mixed-Valence Diferrocenyl Carborane for Molecular Quantum-Dot Cellular Automata Applications.

Science.gov (United States)

Christie, John A; Forrest, Ryan P; Corcelli, Steven A; Wasio, Natalie A; Quardokus, Rebecca C; Brown, Ryan; Kandel, S Alex; Lu, Yuhui; Lent, Craig S; Henderson, Kenneth W

2015-12-14

The preparation of 7-Fc(+) -8-Fc-7,8-nido-[C2 B9 H10 ](-) (Fc(+) FcC2 B9 (-) ) demonstrates the successful incorporation of a carborane cage as an internal counteranion bridging between ferrocene and ferrocenium units. This neutral mixed-valence Fe(II) /Fe(III) complex overcomes the proximal electronic bias imposed by external counterions, a practical limitation in the use of molecular switches. A combination of UV/Vis-NIR spectroscopic and TD-DFT computational studies indicate that electron transfer within Fc(+) FcC2 B9 (-) is achieved through a bridge-mediated mechanism. This electronic framework therefore provides the possibility of an all-neutral null state, a key requirement for the implementation of quantum-dot cellular automata (QCA) molecular computing. The adhesion, ordering, and characterization of Fc(+) FcC2 B9 (-) on Au(111) has been observed by scanning tunneling microscopy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Excited Electronic States Calculated for Cd1−xZnxS Quantum Dots Grown by the Sol-Gel Technique

Directory of Open Access Journals (Sweden)

A. Sakly

2010-01-01

Full Text Available The present paper is aimed to investigate theoretically the quantum confinement in Cd1−xZnxS-related quantum dots with x the atomic fraction of Zn. For both electrons and holes, we have calculated the excited bound states with use of the spherical geometry model and assuming a finite potential at the boundary. For electrons, calculations were made by using Bessel function as an orthonormal basis. However, for holes, the confined subbands have been calculated based on squared quantum well envelope wave functions. The subband energies were evaluated for both electrons and holes versus zinc composition as well.

Effects of sulfurization on the optical properties of Cu2ZnxFe1-xSnS4 thin films

Science.gov (United States)

Hannachi, A.; Oueslati, H.; Khemiri, N.; Kanzari, M.

2017-10-01

In order to prepare thin films of novel semiconductor materials that contain only earth abundant, low cost and nontoxic elements, Cu2ZnxFe1-xSnS4 ingots were successfully synthesized by direct fusion method. Crushed powders of these ingots were used as raw materials for the thermal evaporation. Cu2ZnxFe1-xSnS4 (with x = 0, 0.25, 0.5, 0.75 and 1) thin films were deposited on non-heated glass substrates by vacuum evaporation method. The as deposited films were sulfurized for 30 min at sulfurization temperature Ts = 400 °C. The effects of the sulfurization on the structural and optical properties of CZFTS films were realized by X-ray diffraction (XRD) and UV-Vis spectroscopy. XRD patterns show that all sulfurized CZFTS films were polycrystalline in nature with a preferential orientation along the (112) plane. CFTS films exhibit a stannite structure while CZTS films had a kesterite structure. Optical measurements showed that CZFTS films sulfurized at 400 °C exhibited an optical transmittance between 60 and 80% and all materials had relatively high absorption coefficients in the range of 104-105 cm-1. The band gap energies of sulfurized CZFTS films decreased from 1.71 to 1.50 eV with the increase of the Zn content. The dispersion of the refractive index was discussed in terms of the single oscillator model proposed by Wemple and DiDomenico and the optical parameters such as refractive index, extinction coefficient, oscillator energy and dispersion energy were calculated. The electrical free carrier susceptibility and the carrier concentration on the effective mass ratio were evaluated according to the model of Spitzer and Fan. The hot probe analysis showed that all sulfurized CZFTS films are p-type conductivity.

Origin of CH+ in diffuse molecular clouds. Warm H2 and ion-neutral drift

Science.gov (United States)

Valdivia, Valeska; Godard, Benjamin; Hennebelle, Patrick; Gerin, Maryvonne; Lesaffre, Pierre; Le Bourlot, Jacques

2017-04-01

Context. Molecular clouds are known to be magnetised and to display a turbulent and complex structure where warm and cold phases are interwoven. The turbulent motions within molecular clouds transport molecules, and the presence of magnetic fields induces a relative velocity between neutrals and ions known as the ion-neutral drift (vd). These effects all together can influence the chemical evolution of the clouds. Aims: This paper assesses the roles of two physical phenomena which have previously been invoked to boost the production of CH+ under realistic physical conditions: the presence of warm H2 and the increased formation rate due to the ion-neutral drift. Methods: We performed ideal magnetohydrodynamical (MHD) simulations that include the heating and cooling of the multiphase interstellar medium (ISM), and where we treat dynamically the formation of the H2 molecule. In a post-processing step we compute the abundances of species at chemical equilibrium using a solver that we developed. The solver uses the physical conditions of the gas as input parameters, and can also prescribe the H2 fraction if needed. We validate our approach by showing that the H2 molecule generally has a much longer chemical evolution timescale compared to the other species. Results: We show that CH+ is efficiently formed at the edge of clumps, in regions where the H2 fraction is low (0.3-30%) but nevertheless higher than its equilibrium value, and where the gas temperature is high (≳ 300 K). We show that warm and out of equilibrium H2 increases the integrated column densities of CH+ by one order of magnitude up to values still 3-10 times lower than those observed in the diffuse ISM. We balance the Lorentz force with the ion-neutral drag to estimate the ion-drift velocities from our ideal MHD simulations. We find that the ion-neutral drift velocity distribution peaks around 0.04 km s-1, and that high drift velocities are too rare to have a significant statistical impact on the

Molecular-beam sampling of a hollow-cathode discharge in argon as a plasma diagnostic and a source for fast neutrals

International Nuclear Information System (INIS)

Theuws, P.G.A.; Beijerinck, H.C.W.; Schram, D.C.; Verster, N.F.

1977-01-01

Velocity analysis of the molecular beam is done with a time-of-flight method. The measured velocity distribution of the fast neutral atoms is described by the sum of two Maxwell-Boltzmann distributions with temperatures on the order of 0.25 and 1 eV, respectively. This bimodal distribution is attributed to an overpopulation of the high-energy tail of the ion velocity distribution. The measured intensities of the fast neutrals vary between 5 x 10 14 and 7 x 10 15

Anomalous Hall effect in ZnxFe3-xO4: Universal scaling law and electron localization below the Verwey transition

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N. Jedrecy

2016-08-01

Full Text Available We show that the well-established universal scaling σxyAHE ∼ σxx1.6 between anomalous Hall and longitudinal conductivities in the low conductivity regime (σxx < 104 Ω−1 cm−1 transforms into the scaling σxyAHE ∼ σxx2 at the onset of strong electron localization. The crossover between the two relations is observed in magnetite-derived ZnxFe3-xO4 thin films where an insulating/hopping regime follows a bad metal/hopping regime below the Verwey transition temperature Tv. Our results demonstrate that electron localization effects come into play in the anomalous Hall effect (AHE modifying significantly the scaling exponent. In addition, the thermal evolution of the anomalous Hall resistivity suggests the existence of spin polarons whose size would decrease below Tv.

Epistasis increases the rate of conditionally neutral substitution in an adapting population.

Science.gov (United States)

Draghi, Jeremy A; Parsons, Todd L; Plotkin, Joshua B

2011-04-01

Kimura observed that the rate of neutral substitution should equal the neutral mutation rate. This classic result is central to our understanding of molecular evolution, and it continues to influence phylogenetics, genomics, and the interpretation of evolution experiments. By demonstrating that neutral mutations substitute at a rate independent of population size and selection at linked sites, Kimura provided an influential justification for the idea of a molecular clock and emphasized the importance of genetic drift in shaping molecular evolution. But when epistasis among sites is common, as numerous empirical studies suggest, do neutral mutations substitute according to Kimura's expectation? Here we study simulated, asexual populations of RNA molecules, and we observe that conditionally neutral mutations--i.e., mutations that do not alter the fitness of the individual in which they arise, but that may alter the fitness effects of subsequent mutations--substitute much more often than expected while a population is adapting. We quantify these effects using a simple population-genetic model that elucidates how the substitution rate at conditionally neutral sites depends on the population size, mutation rate, strength of selection, and prevalence of epistasis. We discuss the implications of these results for our understanding of the molecular clock, and for the interpretation of molecular variation in laboratory and natural populations.

Targeting N-Glycan Cryptic Sugar Moieties for Broad-Spectrum Virus Neutralization: Progress in Identifying Conserved Molecular Targets in Viruses of Distinct Phylogenetic Origins

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Denong Wang

2015-03-01

Full Text Available Identifying molecular targets for eliciting broadly virus-neutralizing antibodies is one of the key steps toward development of vaccines against emerging viral pathogens. Owing to genomic and somatic diversities among viral species, identifying protein targets for broad-spectrum virus neutralization is highly challenging even for the same virus, such as HIV-1. However, viruses rely on host glycosylation machineries to synthesize and express glycans and, thereby, may display common carbohydrate moieties. Thus, exploring glycan-binding profiles of broad-spectrum virus-neutralizing agents may provide key information to uncover the carbohydrate-based virus-neutralizing epitopes. In this study, we characterized two broadly HIV-neutralizing agents, human monoclonal antibody 2G12 and Galanthus nivalis lectin (GNA, for their viral targeting activities. Although these agents were known to be specific for oligomannosyl antigens, they differ strikingly in virus-binding activities. The former is HIV-1 specific; the latter is broadly reactive and is able to neutralize viruses of distinct phylogenetic origins, such as HIV-1, severe acute respiratory syndrome coronavirus (SARS-CoV, and human cytomegalovirus (HCMV. In carbohydrate microarray analyses, we explored the molecular basis underlying the striking differences in the spectrum of anti-virus activities of the two probes. Unlike 2G12, which is strictly specific for the high-density Man9GlcNAc2Asn (Man9-clusters, GNA recognizes a number of N-glycan cryptic sugar moieties. These include not only the known oligomannosyl antigens but also previously unrecognized tri-antennary or multi-valent GlcNAc-terminating N-glycan epitopes (Tri/m-Gn. These findings highlight the potential of N-glycan cryptic sugar moieties as conserved targets for broad-spectrum virus neutralization and suggest the GNA-model of glycan-binding warrants focused investigation.

Spotting high-z molecular absorbers using neutral carbon. Results from a complete spectroscopic survey with the VLT

Science.gov (United States)

Noterdaeme, P.; Ledoux, C.; Zou, S.; Petitjean, P.; Srianand, R.; Balashev, S.; López, S.

2018-04-01

While molecular quasar absorption systems provide unique probes of the physical and chemical properties of the gas as well as original constraints on fundamental physics and cosmology, their detection remains challenging. Here we present the results from a complete survey for molecular gas in thirty-nine absorption systems selected solely upon the detection of neutral carbon lines in Sloan Digital Sky Survey (SDSS) spectra, without any prior knowledge of the atomic or molecular gas content. H2 is found in all twelve systems (including seven new detections) where the corresponding lines are covered by the instrument setups and measured to have logN(H2) ≳ 18, indicating a self-shielded regime. We also report seven CO detections (7/39) down to logN(CO) 13.5, including a new one, and put stringent constraints on N(CO) for the remaining 32 systems. N(CO) and N(C I) are found to be strongly correlated with N(CO)/N(C I) 1/10. This suggests that the C I-selected absorber population is probing gas deeper than the H I–H2 transition in which a substantial fraction of the total hydrogen in the cloud is in the form of H2. We conclude that targeting C I-bearing absorbers is a very efficient way to find high-metallicity molecular absorbers. However, probing the molecular content in lower-metallicity regimes as well as high-column-density neutral gas remains to be undertaken to unravel the processes of gas conversion in normal high-z galaxies. Based on observations and archival data from the European Southern Observatory (ESO) prog. IDs 060.A-9024, 072.A-0346, 278.A-5062, 080.A-0482, 080.A-0795, 081.A-0242, 081.A-0334, 082.A-0544, 082.A-0569, 083.A-0454, 084.A-0699, 086.A-0074 and 086.A-0643 using the Ultraviolet and Visual Echelle Spectrograph (UVES) and X-shooter at the Very Large Telescope (VLT), on Cerro Paranal, Chile.

Molecular Doping the Topological Dirac Semimetal Na3Bi across the Charge Neutrality Point with F4-TCNQ.

Science.gov (United States)

Edmonds, Mark T; Hellerstedt, Jack; O'Donnell, Kane M; Tadich, Anton; Fuhrer, Michael S

2016-06-29

We perform low-temperature transport and high-resolution photoelectron spectroscopy on 20 nm thin film topological Dirac semimetal Na3Bi grown by molecular beam epitaxy. We demonstrate efficient electron depletion ∼10(13) cm(-2) of Na3Bi via vacuum deposition of molecular F4-TCNQ without degrading the sample mobility. For samples with low as-grown n-type doping (1 × 10(12) cm(-2)), F4-TCNQ doping can achieve charge neutrality and even a net p-type doping. Photoelectron spectroscopy and density functional theory are utilized to investigate the behavior of F4-TCNQ on the Na3Bi surface.

Inertia-Centric Stability Analysis of a Planar Uniform Dust Molecular Cloud with Weak Neutral-Charged Dust Frictional Coupling

Science.gov (United States)

K. Karmakar, P.; Borah, B.

2014-05-01

This paper adopts an inertia-centric evolutionary model to study the excitation mechanism of new gravito-electrostatic eigenmode structures in a one-dimensional (1-D) planar self-gravitating dust molecular cloud (DMC) on the Jeans scale. A quasi-neutral multi-fluid consisting of warm electrons, warm ions, neutral gas and identical inertial cold dust grains with partial ionization is considered. The grain-charge is assumed not to vary at the fluctuation evolution time scale. The neutral gas particles form the background, which is weakly coupled with the collapsing grainy plasma mass. The gravitational decoupling of the background neutral particles is justifiable for a higher inertial mass of the grains with higher neutral population density so that the Jeans mode frequency becomes reasonably large. Its physical basis is the Jeans assumption of a self-gravitating uniform medium adopted for fiducially analytical simplification by neglecting the zero-order field. So, the equilibrium is justifiably treated initially as “homogeneous”. The efficacious inertial role of the thermal species amidst weak collisions of the neutral-charged grains is taken into account. A standard multiscale technique over the gravito-electrostatic equilibrium yields a unique pair of Korteweg-de Vries (KdV) equations. It is integrated numerically by the fourth-order Runge-Kutta method with multi-parameter variation for exact shape analyses. Interestingly, the model is conducive for the propagation of new conservative solitary spectral patterns. Their basic physics, parametric features and unique characteristics are discussed. The results go qualitatively in good correspondence with the earlier observations made by others. Tentative applications relevant to space and astrophysical environments are concisely highlighted.

Simultaneous ion and neutral evaporation in aqueous nanodrops: experiment, theory, and molecular dynamics simulations.

Science.gov (United States)

Higashi, Hidenori; Tokumi, Takuya; Hogan, Christopher J; Suda, Hiroshi; Seto, Takafumi; Otani, Yoshio

2015-06-28

We use a combination of tandem ion mobility spectrometry (IMS-IMS, with differential mobility analyzers), molecular dynamics (MD) simulations, and analytical models to examine both neutral solvent (H2O) and ion (solvated Na(+)) evaporation from aqueous sodium chloride nanodrops. For experiments, nanodrops were produced via electrospray ionization (ESI) of an aqueous sodium chloride solution. Two nanodrops were examined in MD simulations: a 2500 water molecule nanodrop with 68 Na(+) and 60 Cl(-) ions (an initial net charge of z = +8), and (2) a 1000 water molecule nanodrop with 65 Na(+) and 60 Cl(-) ions (an initial net charge of z = +5). Specifically, we used MD simulations to examine the validity of a model for the neutral evaporation rate incorporating both the Kelvin (surface curvature) and Thomson (electrostatic) influences, while both MD simulations and experimental measurements were compared to predictions of the ion evaporation rate equation of Labowsky et al. [Anal. Chim. Acta, 2000, 406, 105-118]. Within a single fit parameter, we find excellent agreement between simulated and modeled neutral evaporation rates for nanodrops with solute volume fractions below 0.30. Similarly, MD simulation inferred ion evaporation rates are in excellent agreement with predictions based on the Labowsky et al. equation. Measurements of the sizes and charge states of ESI generated NaCl clusters suggest that the charge states of these clusters are governed by ion evaporation, however, ion evaporation appears to have occurred with lower activation energies in experiments than was anticipated based on analytical calculations as well as MD simulations. Several possible reasons for this discrepancy are discussed.

Effect of Zn addition on structural, magnetic properties, antistructural modeling of Co1-xZnxFe2O4 nano ferrite

Science.gov (United States)

Raghuvanshi, S.; Kane, S. N.; Tatarchuk, T. R.; Mazaleyrat, F.

2018-05-01

Effect of Zn addition on cationic distribution, structural properties, magnetic properties, antistructural modeling of nanocrystalline Co1-xZnxFe2O4 (0.08 ≤ x ≤ 0.56) ferrite is reported. XRD confirms the formation of single phase cubic spinel nano ferrites with average grain diameter ranging between 41.2 - 54.9 nm. Coercivity (Hc), anisotropy constant (K1) decreases with Zn addition, but experimental, theoretical saturation magnetization (Ms, Ms(t)) increases upto x = 0.32, then decreases, attributed to the breaking of collinear ferrimagnetic phase. Variation of magnetic properties is correlated with cationic distribution. A new antistructural modeling for describing active surface centers is discussed to explain change in concentration of donor's active centers Zn'B, Co'B, acceptor's active centers Fe*A are explained.

Nearly Neutral Evolution Across the Drosophila melanogaster Genome

DEFF Research Database (Denmark)

Esteve, David Castellano; James, Jennifer; Eyre-Walker, Adam

2017-01-01

Under the nearly neutral theory of molecular evolution the proportion of effectively neutral mutations is expected to depend upon the effective population size (Ne). Here we investigate whether this is the case across the genome of Drosophila melanogaster using polymorphism data from 128 North...

Theoretical study of a neutral, doubly protonated, and doubly deprotonated porphyrin dithiolate used as a molecular switch

International Nuclear Information System (INIS)

Girard, Yvan; Kondo, Masakazu; Yoshizawa, Kazunari

2006-01-01

The zero-bias conductance of the neutral, doubly protonated, and doubly deprotonated porphyrin molecules used as molecular junctions between gold electrodes is investigated by using a Green's function formalism combined with density functional theory calculations. The probability for an electron to scatter through the porphyrin is predicted to be significantly increased by the protonation or the deprotonation, and the molecule could be used as a switch controlled by the pH. The shapes and energies of the frontier orbitals are used to rationalize these results

Synthesis and growth mechanism of Zn0.5Cd0.5S nanohexagon dendrite

Science.gov (United States)

Yu, Wen; Fang, Pengfei; Wang, Shaojie

2014-12-01

Hierarchical Zn0.5Cd0.5S nanohexagon dendrites were synthesized by a one-step hydrothermal method. The Zn0.5Cd0.5S nanohexagon dendrites were made up of nanohexagons with a side length of about 90 nm. The nanohexagons were regularly arranged forming as embranchments which were parallel to each other along certain hexagonal directions. Furthermore, these embranchments made up primary trunks shaping as dendrites. The growth mechanism of Zn0.5Cd0.5S nanohexagon dendrites was proposed in which molecular soft template and lowest energy principle played key roles. By adjusting the composition of the reactants, a series of ZnxCd1-xS solid solutions could be obtained. The morphology of the synthesized ZnxCd1-xS depended much on the x value. The UV-vis spectra absorb edges of the ZnxCd1-xS samples continuously shifted indicating the changes of the band gap.

Monte Carlo neutral density calculations for ELMO Bumpy Torus

International Nuclear Information System (INIS)

Davis, W.A.; Colchin, R.J.

1986-11-01

The steady-state nature of the ELMO Bumpy Torus (EBT) plasma implies that the neutral density at any point inside the plasma volume will determine the local particle confinement time. This paper describes a Monte Carlo calculation of three-dimensional atomic and molecular neutral density profiles in EBT. The calculation has been done using various models for neutral source points, for launching schemes, for plasma profiles, and for plasma densities and temperatures. Calculated results are compared with experimental observations - principally spectroscopic measurements - both for guidance in normalization and for overall consistency checks. Implications of the predicted neutral profiles for the fast-ion-decay measurement of neutral densities are also addressed

Mg1-xZnxFe2O4 nanoparticles: Interplay between cation distribution and magnetic properties

Directory of Open Access Journals (Sweden)

S. Raghuvanshi

2018-04-01

Full Text Available Correlation between cationic distribution, magnetic properties of Mg1-xZnxFe2O4 (0.0 ≤ x ≤ 1.0 ferrite is demonstrated, hardly shown in literature. X-ray diffraction (XRD confirms the formation of cubic spinel nano ferrites with grain diameter between 40.8 to 55.4 nm. Energy dispersive spectroscopy (EDS confirms close agreement of Mg/Fe, Zn/Fe molar ratio, presence of all elements (Mg, Zn, Fe, O, formation of estimated ferrite composition. Zn addition (for Mg shows: i linear increase of lattice parameter aexp, accounted for replacement of an ion with higher ionic radius (Zn > Mg; ii presence of higher population of Fe3+ ions on B site, and unusual occurrence of Zn, Mg on A and B site leads to non-equilibrium cation distribution where we observe inverse to mixed structure, and is in contrast to reported literature where inverse to normal transition is reported; iii effect on A-A, A-B, B-B exchange interactions, affecting coercivity Hc, Ms. A new empirical relation is also obtained showing linear relation between saturation magnetization Ms – inversion parameter δ, oxygen parameter u4¯3m. Non-zero Y-K angle (αYK values implies Y-K type magnetic ordering in the studied samples.

Reversible Masking Using Low-Molecular-Weight Neutral Lipids to Achieve Optimal-Targeted Delivery

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Nancy Smyth Templeton

2012-01-01

Full Text Available Intravenous injection of therapeutics is required to effectively treat or cure metastatic cancer, certain cardiovascular diseases, and other acquired or inherited diseases. Using this route of delivery allows potential uptake in all disease targets that are accessed by the bloodstream. However, normal tissues and organs also have the potential for uptake of therapeutic agents. Therefore, investigators have used targeted delivery to attempt delivery solely to the target cells; however, use of ligands on the surface of delivery vehicles to target specific cell surface receptors is not sufficient to avoid nonspecific uptake. PEGylation has been used for decades to try to avoid nonspecific uptake but suffers from many problems known as “The PEGylation Dilemma.” We have solved this dilemma by replacing PEGylation with reversible masking using low-molecular-weight neutral lipids in order to achieve optimal-targeted delivery solely to target cells. Our paper will focus on this topic.

Applying ecological models to communities of genetic elements: the case of neutral theory.

Science.gov (United States)

Linquist, Stefan; Cottenie, Karl; Elliott, Tyler A; Saylor, Brent; Kremer, Stefan C; Gregory, T Ryan

2015-07-01

A promising recent development in molecular biology involves viewing the genome as a mini-ecosystem, where genetic elements are compared to organisms and the surrounding cellular and genomic structures are regarded as the local environment. Here, we critically evaluate the prospects of ecological neutral theory (ENT), a popular model in ecology, as it applies at the genomic level. This assessment requires an overview of the controversy surrounding neutral models in community ecology. In particular, we discuss the limitations of using ENT both as an explanation of community dynamics and as a null hypothesis. We then analyse a case study in which ENT has been applied to genomic data. Our central finding is that genetic elements do not conform to the requirements of ENT once its assumptions and limitations are made explicit. We further compare this genome-level application of ENT to two other, more familiar approaches in genomics that rely on neutral mechanisms: Kimura's molecular neutral theory and Lynch's mutational-hazard model. Interestingly, this comparison reveals that there are two distinct concepts of neutrality associated with these models, which we dub 'fitness neutrality' and 'competitive neutrality'. This distinction helps to clarify the various roles for neutral models in genomics, for example in explaining the evolution of genome size. © 2015 John Wiley & Sons Ltd.

Neutralizing Activity of Broadly Neutralizing Anti-HIV-1 Antibodies against Clade B Clinical Isolates Produced in Peripheral Blood Mononuclear Cells.

Science.gov (United States)

Cohen, Yehuda Z; Lorenzi, Julio C C; Seaman, Michael S; Nogueira, Lilian; Schoofs, Till; Krassnig, Lisa; Butler, Allison; Millard, Katrina; Fitzsimons, Tomas; Daniell, Xiaoju; Dizon, Juan P; Shimeliovich, Irina; Montefiori, David C; Caskey, Marina; Nussenzweig, Michel C

2018-03-01

Recently discovered broadly neutralizing antibodies (bNAbs) against HIV-1 demonstrate extensive breadth and potency against diverse HIV-1 strains and represent a promising approach for the treatment and prevention of HIV-1 infection. The breadth and potency of these antibodies have primarily been evaluated by using panels of HIV-1 Env-pseudotyped viruses produced in 293T cells expressing molecularly cloned Env proteins. Here we report on the ability of five bNAbs currently in clinical development to neutralize circulating primary HIV-1 isolates derived from peripheral blood mononuclear cells (PBMCs) and compare the results to those obtained with the pseudovirus panels used to characterize the bNAbs. The five bNAbs demonstrated significantly less breadth and potency against clinical isolates produced in PBMCs than against Env-pseudotyped viruses. The magnitude of this difference in neutralizing activity varied, depending on the antibody epitope. Glycan-targeting antibodies showed differences of only 3- to 4-fold, while antibody 10E8, which targets the membrane-proximal external region, showed a nearly 100-fold decrease in activity between published Env-pseudotyped virus panels and PBMC-derived primary isolates. Utilizing clonal PBMC-derived primary isolates and molecular clones, we determined that the observed discrepancy in bNAb performance is due to the increased sensitivity to neutralization exhibited by 293T-produced Env-pseudotyped viruses. We also found that while full-length molecularly cloned viruses produced in 293T cells exhibit greater sensitivity to neutralization than PBMC-derived viruses do, Env-pseudotyped viruses produced in 293T cells generally exhibit even greater sensitivity to neutralization. As the clinical development of bNAbs progresses, it will be critical to determine the relevance of each of these in vitro neutralization assays to in vivo antibody performance. IMPORTANCE Novel therapeutic and preventive strategies are needed to contain the

An Efficient and Stable Hydrophobic Molecular Cobalt Catalyst for Water Electro-oxidation at Neutral pH

KAUST Repository

Chen, Ba-Tian

2016-06-14

The synthesis of a library of molecular water oxidation catalysts based on the Co complex of tris(2-benzimidazolylmethyl)amine is described. Hydrophobicity was identified as the key variable in mediating the catalytic competence of the complexes. The change in this parameter correlates with both the conformational mobility of the ligand core and the structural changes in the local solvent environment around the metal site. The optimal Co complex identified is hydrophobic, because of three semifluorinated side chains. It catalyzes water electro-oxidation efficiently at neutral pH, with an overpotential of 390 mV and a turnover frequency (TOF) of 1.83 s-1 in the absence of soluble Co salts. The catalyst can be immobilized through physisorption, and it remains stable in prolonged electrolysis experiments. © 2016 American Chemical Society.

An Efficient and Stable Hydrophobic Molecular Cobalt Catalyst for Water Electro-oxidation at Neutral pH

KAUST Repository

Chen, Batian; Morlanes, Natalia Sanchez; Adogla, Enoch; Takanabe, Kazuhiro; Rodionov, Valentin

2016-01-01

The synthesis of a library of molecular water oxidation catalysts based on the Co complex of tris(2-benzimidazolylmethyl)amine is described. Hydrophobicity was identified as the key variable in mediating the catalytic competence of the complexes. The change in this parameter correlates with both the conformational mobility of the ligand core and the structural changes in the local solvent environment around the metal site. The optimal Co complex identified is hydrophobic, because of three semifluorinated side chains. It catalyzes water electro-oxidation efficiently at neutral pH, with an overpotential of 390 mV and a turnover frequency (TOF) of 1.83 s-1 in the absence of soluble Co salts. The catalyst can be immobilized through physisorption, and it remains stable in prolonged electrolysis experiments. © 2016 American Chemical Society.

Neutralizing Antibodies and Pathogenesis of Hepatitis C Virus Infection

Directory of Open Access Journals (Sweden)

Françoise Stoll-Keller

2012-10-01

Full Text Available Hepatitis C virus (HCV infection is a major cause of chronic liver disease worldwide. The interplay between the virus and host innate and adaptive immune responses determines the outcome of infection. There is increasing evidence that host neutralizing responses play a relevant role in the resulting pathogenesis. Furthermore, viral evasion from host neutralizing antibodies has been revealed to be an important contributor in leading both to viral persistence in acute liver graft infection following liver transplantation, and to chronic viral infection. The development of novel model systems to study HCV entry and neutralization has allowed a detailed understanding of the molecular mechanisms of virus-host interactions during antibody-mediated neutralization. The understanding of these mechanisms will ultimately contribute to the development of novel antiviral preventive strategies for liver graft infection and an urgently needed vaccine. This review summarizes recent concepts of the role of neutralizing antibodies in viral clearance and protection, and highlights consequences of viral escape from neutralizing antibodies in the pathogenesis of HCV infection.

TWO-FLUID MAGNETOHYDRODYNAMICS SIMULATIONS OF CONVERGING H I FLOWS IN THE INTERSTELLAR MEDIUM. II. ARE MOLECULAR CLOUDS GENERATED DIRECTLY FROM A WARM NEUTRAL MEDIUM?

International Nuclear Information System (INIS)

Inoue, Tsuyoshi; Inutsuka, Shu-ichiro

2009-01-01

Formation of interstellar clouds as a consequence of thermal instability is studied using two-dimensional two-fluid magnetohydrodynamic simulations. We consider the situation of converging, supersonic flows of warm neutral medium in the interstellar medium that generate a shocked slab of thermally unstable gas in which clouds form. We find, as speculated in Paper I, that in the shocked slab magnetic pressure dominates thermal pressure and the thermal instability grows in the isochorically cooling, thermally unstable slab that leads to the formation of H I clouds whose number density is typically n ∼ -3 , even if the angle between magnetic field and converging flows is small. We also find that even if there is a large dispersion of magnetic field, evolution of the shocked slab is essentially determined by the angle between the mean magnetic field and converging flows. Thus, the direct formation of molecular clouds by piling up warm neutral medium does not seem to be a typical molecular cloud formation process, unless the direction of supersonic converging flows is biased to the orientation of mean magnetic field by some mechanism. However, when the angle is small, the H I shell generated as a result of converging flows is massive and possibly evolves into molecular clouds, provided gas in the massive H I shell is piled up again along the magnetic field line. We expect that another subsequent shock wave can again pile up the gas of the massive shell and produce a larger cloud. We thus emphasize the importance of multiple episodes of converging flows, as a typical formation process of molecular clouds.

Neutral hydrogen in the post-reionization universe

Science.gov (United States)

Padmanabhan, Hamsa

2018-05-01

The evolution of neutral hydrogen (HI) across redshifts is a powerful probe of cosmology, large scale structure in the universe and the intergalactic medium. Using a data-driven halo model to describe the distribution of HI in the post-reionization universe (z ~ 5 to 0), we obtain the best-fitting parameters from a rich sample of observational data: low redshift 21-cm emission line studies, intermediate redshift intensity mapping experiments, and higher redshift Damped Lyman Alpha (DLA) observations. Our model describes the abundance and clustering of neutral hydrogen across redshifts 0 - 5, and is useful for investigating different aspects of galaxy evolution and for comparison with hydrodynamical simulations. The framework can be applied for forecasting future observations with neutral hydrogen, and extended to the case of intensity mapping with molecular and other line transitions at intermediate redshifts.

Midplane neutral density profiles in the National Spherical Torus Experiment

Energy Technology Data Exchange (ETDEWEB)

Stotler, D. P., E-mail: dstotler@pppl.gov; Bell, R. E.; Diallo, A.; LeBlanc, B. P.; Podestà, M.; Roquemore, A. L.; Ross, P. W. [Princeton Plasma Physics Laboratory, Princeton University, P. O. Box 451, Princeton, New Jersey 08543-0451 (United States); Scotti, F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2015-08-15

Atomic and molecular density data in the outer midplane of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] are inferred from tangential camera data via a forward modeling procedure using the DEGAS 2 Monte Carlo neutral transport code. The observed Balmer-β light emission data from 17 shots during the 2010 NSTX campaign display no obvious trends with discharge parameters such as the divertor Balmer-α emission level or edge deuterium ion density. Simulations of 12 time slices in 7 of these discharges produce molecular densities near the vacuum vessel wall of 2–8 × 10{sup 17 }m{sup −3} and atomic densities ranging from 1 to 7 × 10{sup 16 }m{sup −3}; neither has a clear correlation with other parameters. Validation of the technique, begun in an earlier publication, is continued with an assessment of the sensitivity of the simulated camera image and neutral densities to uncertainties in the data input to the model. The simulated camera image is sensitive to the plasma profiles and virtually nothing else. The neutral densities at the vessel wall depend most strongly on the spatial distribution of the source; simulations with a localized neutral source yield densities within a factor of two of the baseline, uniform source, case. The uncertainties in the neutral densities associated with other model inputs and assumptions are ≤50%.

Crystal engineering of a zwitterionic drug to neutral cocrystals: a general solution for floxacins.

Science.gov (United States)

Gunnam, Anilkumar; Suresh, Kuthuru; Ganduri, Ramesh; Nangia, Ashwini

2016-10-18

The transformation of zwitterionic Sparfloxacin (SPX) to the neutral form is achieved by cocrystallization. Neutral forms of drugs are important for higher membrane permeability, while zwitterions are more soluble in water. The twin advantages of higher solubility/dissolution rate and good stability of neutral SPX are achieved in a molecular cocrystal compared to its zwitterionic SPX hydrate. The amine-phenol supramolecular synthon drives cocrystal formation, with the paraben ester acting as a "proton migrator" for the ionic to neutral transformation.

Production and transformation of dissolved neutral sugars and amino acids by bacteria in seawater

DEFF Research Database (Denmark)

Jørgensen, Linda; Lechtenfeld, O.J.; Benner, R.

2014-01-01

production and degradation processes. This study provides insight into the bioavailability of biomolecules as well as the chemical composition of DOM produced by bacteria. The molecular compositions of combined neutral sugars and amino acids were investigated in DOM produced by bacteria and in DOM remaining...... degradation are not strongly influenced by the initial substrate or bacterial community. The molecular composition of neutral sugars released by bacteria was characterized by a high glucose content (47 mol %) and heterogeneous contributions from other neutral sugars (3–14 mol %). DOM remaining after bacterial...... degradation was characterized by a high galactose content (33 mol %), followed by glucose (22 mol %) and the remaining neutral sugars (7–11 mol %). The ratio of D-amino acids to L-amino acids increased during the experiments as a response to bacterial degradation, and after 32 days, the D/L ratios of aspartic...

Are "Market Neutral" Hedge Funds Really Market Neutral?

OpenAIRE

Andrew J. Patton

2009-01-01

Using a variety of different definitions of "neutrality," this study presents significant evidence against the neutrality to market risk of hedge funds in a range of style categories. I generalize standard definitions of "market neutrality," and propose five different neutrality concepts. I suggest statistical tests for each neutrality concept, and apply these tests to a database of monthly returns on 1423 hedge funds from five style categories. For the "market neutral" style, approximately o...

Magnetohydrodynamic shocks in molecular clouds

International Nuclear Information System (INIS)

Chernoff, D.F.

1985-01-01

Part one develops the mathematical and physical theory of one-dimensional, time-independent subalfvenic flow in partially ionized gas with magnetic fields, for application to shocks in molecular clouds. Unlike normal gas-dynamic shocks, the neutral flow may be continuous and cool if the gas radiates efficiently and does not self-ionize. Analytic solutions are given in the limit that the neutral gas is either adiabatic or isothermal (cold). Numerical techniques are developed and applied to find the neutral flow under general circumstances. Part two extends the theory and results of part one in three ways: (1) to faster, superalfvenic flow, (2) to complex gases containing heavy charged particles (grains) in addition to ions, containing heavy charged particles (grains) in addition to ions, electrons and neutrals, and (3) to the entire range in (Omega tau), the ratio of charged particle damping time to gyroperiod, expected in gas flows in molecular clouds

ZnO nanoparticles sensitized by CuInZnxS2+x quantum dots as highly efficient solar light driven photocatalysts

Directory of Open Access Journals (Sweden)

Florian Donat

2017-05-01

Full Text Available Alloyed CuInZnxS2+x (ZCIS quantum dots (QDs were successfully associated to ZnO nanoparticles by a thermal treatment at 400 °C for 15 min. The ZnO/ZCIS composite was characterized by TEM, SEM, XRD, XPS and UV–vis absorption spectroscopy. ZCIS QDs, with an average diameter of ≈4.5 nm, were found to be homogeneously distributed at the surface of ZnO nanoparticles. ZCIS-sensitized ZnO nanoparticles exhibit a high photocatalytic activity under simulated solar light irradiation for the degradation of Orange II dye (>95% degradation after 180 min of irradiation at an intensity of 5 mW/cm2. The heterojunction built between the ZnO nanoparticle and ZCIS QDs not only extends the light adsorption range by the photocatalyst but also acts to decrease electron/hole recombination. Interestingly, the ZnO/ZCIS composite was found to produce increased amounts of H2O2 and singlet oxygen 1O2 compared to ZnO, suggesting that these reactive oxygen species play a key role in the photodegradation mechanism. The activity of the ZnO/ZCIS composite is retained at over 90% of its original value after ten successive photocatalytic runs, indicating its high stability and its potential for practical photocatalytic applications.

Biomolecule-assisted synthesis of defect-mediated Cd1-xZnxS/MoS2/graphene hollow spheres for highly efficient hydrogen evolution.

Science.gov (United States)

Du, Ruifeng; Zhang, Yihe; Li, Baoying; Yu, Xuelian; Liu, Huijuan; An, Xiaoqiang; Qu, Jiuhui

2016-06-28

Moderate efficiency and the utilization of noble metal cocatalysts are the key factors that restrict the large-scale application of photocatalytic hydrogen production. To develop more efficient photocatalysts based on earth abundant elements, either a new material strategy or a fundamental understanding of the semiconductor/cocatalyst interfaces is highly desirable. In this paper, we studied the feasibility of in situ formation of defect-rich cocatalysts on graphene-based photocatalysts. A facile biomolecule-assisted strategy was used to self-assmble Cd1-xZnxS/MoS2/graphene hollow spheres. The defect-mediated cocatalyst and synergetic charge transfer around heterostructured interfaces exhibit a significant impact on the visible-light-driven photocatalytic activity of multicomponent solid solutions. With engineered interfacial defects, Cd0.8Zn0.2S/MoS2/graphene hollow spheres exhibited a 63-fold improved H2 production rate, which was even 2 and 3.8 times higher than those of CdS/MoS2/graphene hollow spheres and Cd0.8Zn0.2S/Pt. Therefore, our research provides a promising approach for the rational design of high-efficiency and low-cost photocatalysts for solar fuel production.

Functional conservation of nucleosome formation selectively biases presumably neutral molecular variation in yeast genomes.

Science.gov (United States)

Babbitt, Gregory A; Cotter, C R

2011-01-01

One prominent pattern of mutational frequency, long appreciated in comparative genomics, is the bias of purine/pyrimidine conserving substitutions (transitions) over purine/pyrimidine altering substitutions (transversions). Traditionally, this transitional bias has been thought to be driven by the underlying rates of DNA mutation and/or repair. However, recent sequencing studies of mutation accumulation lines in model organisms demonstrate that substitutions generally do not accumulate at rates that would indicate a transitional bias. These observations have called into question a very basic assumption of molecular evolution; that naturally occurring patterns of molecular variation in noncoding regions accurately reflect the underlying processes of randomly accumulating neutral mutation in nuclear genomes. Here, in Saccharomyces yeasts, we report a very strong inverse association (r = -0.951, P < 0.004) between the genome-wide frequency of substitutions and their average energetic effect on nucleosome formation, as predicted by a structurally based energy model of DNA deformation around the nucleosome core. We find that transitions occurring at sites positioned nearest the nucleosome surface, which are believed to function most importantly in nucleosome formation, alter the deformation energy of DNA to the nucleosome core by only a fraction of the energy changes typical of most transversions. When we examined the same substitutions set against random background sequences as well as an existing study reporting substitutions arising in mutation accumulation lines of Saccharomyces cerevisiae, we failed to find a similar relationship. These results support the idea that natural selection acting to functionally conserve chromatin organization may contribute significantly to genome-wide transitional bias, even in noncoding regions. Because nucleosome core structure is highly conserved across eukaryotes, our observations may also help to further explain locally elevated

Spatial structure of morphological and neutral genetic variation in Brook Trout

Science.gov (United States)

Kazyak, David C.; Hilderbrand, Robert H.; Keller, Stephen R.; Colaw, Mark C.; Holloway, Amanda E.; Morgan, Raymond P.; King, Timothy L.

2015-01-01

Brook Trout Salvelinus fontinalis exhibit exceptional levels of life history variation, remarkable genetic variability, and fine-scale population structure. In many cases, neighboring populations may be highly differentiated from one another to an extent that is comparable with species-level distinctions in other taxa. Although genetic samples have been collected from hundreds of populations and tens of thousands of individuals, little is known about whether differentiation at neutral markers reflects phenotypic differences among Brook Trout populations. We compared differentiation in morphology and neutral molecular markers among populations from four geographically proximate locations (all within 24 km) to examine how genetic diversity covaries with morphology. We found significant differences among and/or within streams for all three morphological axes examined and identified the source stream of many individuals based on morphology (52.3% classification efficiency). Although molecular and morphological differentiation among streams ranged considerably (mean pairwise FST: 0.023–0.264; pairwise PST: 0.000–0.339), the two measures were not significantly correlated. While in some cases morphological characters appear to have diverged to a greater extent than expected by neutral genetic drift, many traits were conserved to a greater extent than were neutral genetic markers. Thus, while Brook Trout exhibit fine-scale spatial patterns in both morphology and neutral genetic diversity, these types of biological variabilities are being structured by different ecological and evolutionary processes. The relative influences of genetic drift versus selection and phenotypic plasticity in shaping morphology appear to vary among populations occupying nearby streams.

Neutralization of HIV-1: a paradox of humoral proportions

NARCIS (Netherlands)

Nara, P. L.; Garrity, R. R.; Goudsmit, J.

1991-01-01

The production of immunoglobulin capable of neutralizing the infectivity of a virus represents one of the most remarkable molecular accomplishments of the host's available immune defenses. It should be no surprise that a virus that has existed in the parenchyma of the immune system has evolved as an

On becoming neutral: effects of experimental neutralizing reconsidered.

Science.gov (United States)

van den Hout, M; van Pol, M; Peters, M

2001-12-01

Behaviour Research and Therapy 34 (1996) 889-898 found that writing out a negative thought produced anxiety and an urge to neutralize the thought, that instructing participants to neutralize the thought reduced anxiety/neutralization urge in the short run (i.e. within 2 min), but that in the control group 20 min without instruction was attended by the same reduction in anxiety/urge to neutralize ("natural decay"). The observations were made with pariticipants who scored high on "thought action fusion" and the experiment was set up as exerimental model of obsessions. We repeated the study with participants that were not selected on thought action fusion. All the findings reported by Behaviour Research and Therapy 34 (1996) 889-898 were replicated. Correlational analysis indicated that the strength of the effect was not related to scores on scales measuring "thought action fusion". Behaviour Research and Therapy 34 (1996) 889-898 did not assess whether non-neutralizing was followed by immediate reductions in distress. We did assess this and found that the larger part of the immediate reduction of distress after neutralization also occurs when no neutralization instruction is given. The effects of neutralization instructions in the present type of experiment are considerably less powerful than suggested earlier.

Free energy landscape of siRNA-polycation complexation: Elucidating the effect of molecular geometry, polymer flexibility, and charge neutralization.

Directory of Open Access Journals (Sweden)

Gianvito Grasso

Full Text Available The success of medical threatments with DNA and silencing interference RNA is strongly related to the design of efficient delivery technologies. Cationic polymers represent an attractive strategy to serve as nucleic-acid carriers with the envisioned advantages of efficient complexation, low cost, ease of production, well-defined size, and low polydispersity index. However, the balance between efficacy and toxicity (safety of these polymers is a challenge and in need of improvement. With the aim of designing more effective polycationic-based gene carriers, many parameters such as carrier morphology, size, molecular weight, surface chemistry, and flexibility/rigidity ratio need to be taken into consideration. In the present work, the binding mechanism of three cationic polymers (polyarginine, polylysine and polyethyleneimine to a model siRNA target is computationally investigated at the atomistic level. In order to better understand the polycationic carrier-siRNA interactions, replica exchange molecular dynamic simulations were carried out to provide an exhaustive exploration of all the possible binding sites, taking fully into account the siRNA flexibility together with the presence of explicit solvent and ions. Moreover, well-tempered metadynamics simulations were employed to elucidate how molecular geometry, polycation flexibility, and charge neutralization affect the siRNA-polycations free energy landscape in term of low-energy binding modes and unbinding free energy barriers. Significant differences among polymer binding modes have been detected, revealing the advantageous binding properties of polyarginine and polylysine compared to polyethyleneimine.

Integral Transport Analysis Results for Ions Flowing Through Neutral Gas

Science.gov (United States)

Emmert, Gilbert; Santarius, John

2017-10-01

Results of a computational model for the flow of energetic ions and neutrals through a background neutral gas will be presented. The method models reactions as creating a new source of ions or neutrals if the energy or charge state of the resulting particle is changed. For a given source boundary condition, the creation and annihilation of the various species is formulated as a 1-D Volterra integral equation that can quickly be solved numerically by finite differences. The present work focuses on multiple-pass, 1-D ion flow through neutral gas and a nearly transparent, concentric anode and cathode pair in spherical, cylindrical, or linear geometry. This has been implemented as a computer code for atomic (3He, 3He +, 3He + +) and molecular (D, D2, D-, D +, D2 +, D3 +) ion and neutral species, and applied to modeling inertial-electrostatic connement (IEC) devices. The code yields detailed energy spectra of the various ions and energetic neutral species. Calculations for several University of Wisconsin IEC and ion implantation devices will be presented. Research supported by US Dept. of Homeland Security Grant 2015-DN-077-ARI095, Dept. of Energy Grant DE-FG02-04ER54745, and the Grainger Foundation.

Neutral evolution of proteins: The superfunnel in sequence space and its relation to mutational robustness

Science.gov (United States)

Noirel, Josselin; Simonson, Thomas

2008-11-01

Following Kimura's neutral theory of molecular evolution [M. Kimura, The Neutral Theory of Molecular Evolution (Cambridge University Press, Cambridge, 1983) (reprinted in 1986)], it has become common to assume that the vast majority of viable mutations of a gene confer little or no functional advantage. Yet, in silico models of protein evolution have shown that mutational robustness of sequences could be selected for, even in the context of neutral evolution. The evolution of a biological population can be seen as a diffusion on the network of viable sequences. This network is called a "neutral network." Depending on the mutation rate μ and the population size N, the biological population can evolve purely randomly (μN ≪1) or it can evolve in such a way as to select for sequences of higher mutational robustness (μN ≫1). The stringency of the selection depends not only on the product μN but also on the exact topology of the neutral network, the special arrangement of which was named "superfunnel." Even though the relation between mutation rate, population size, and selection was thoroughly investigated, a study of the salient topological features of the superfunnel that could affect the strength of the selection was wanting. This question is addressed in this study. We use two different models of proteins: on lattice and off lattice. We compare neutral networks computed using these models to random networks. From this, we identify two important factors of the topology that determine the stringency of the selection for mutationally robust sequences. First, the presence of highly connected nodes ("hubs") in the network increases the selection for mutationally robust sequences. Second, the stringency of the selection increases when the correlation between a sequence's mutational robustness and its neighbors' increases. The latter finding relates a global characteristic of the neutral network to a local one, which is attainable through experiments or molecular

Statistical theory of neutral protein evolution by random site mutations

Indian Academy of Sciences (India)

Administrator

Understanding the features of the protein conformational space represents a key component to characterize ... Neutral evolution; protein design; mutations; foldability criteria. 1. Introduction ... analysis of the vast evolutionary landscape is re- ... intra-molecular interactions in the protein which may not be ... This is the main in-.

Analysis of particle species evolution in neutral beam injection lines

International Nuclear Information System (INIS)

Kim, J.; Haselton, H.H.

1978-07-01

Analytic solutions to the rate equations describing the species evolution of a multispecies positive ion beam of hydrogen due to charge exchange and molecular dissociation are derived as a function of the background gas (H 2 ) line density in the neutralizing gas cell and in the drift tube. Using the solutions, calculations are presented for the relative abundance of each species as a function of the gas cell thickness, the reionization loss rates in the drift tube, and the neutral beam power as a function of the beam energy and the species composition of the original ion beam

Ethambutol neutralizes lysosomes and causes lysosomal zinc accumulation.

Science.gov (United States)

Yamada, Daisuke; Saiki, Shinji; Furuya, Norihiko; Ishikawa, Kei-Ichi; Imamichi, Yoko; Kambe, Taiho; Fujimura, Tsutomu; Ueno, Takashi; Koike, Masato; Sumiyoshi, Katsuhiko; Hattori, Nobutaka

2016-02-26

Ethambutol is a common medicine used for the treatment of tuberculosis, which can have serious side effects, such as retinal and liver dysfunction. Although ethambutol has been reported to impair autophagic flux in rat retinal cells, the precise molecular mechanism remains unclear. Using various mammalian cell lines, we showed that ethambutol accumulated in autophagosomes and vacuolated lysosomes, with marked Zn(2+) accumulation. The enlarged lysosomes were neutralized and were infiltrated with Zn(2+) accumulations in the lysosomes, with simultaneous loss of acidification. These results suggest that EB neutralizes lysosomes leading to insufficient autophagy, implying that some of the adverse effects associated with EB in various organs may be of this mechanism. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Human genomic disease variants: a neutral evolutionary explanation.

Science.gov (United States)

Dudley, Joel T; Kim, Yuseob; Liu, Li; Markov, Glenn J; Gerold, Kristyn; Chen, Rong; Butte, Atul J; Kumar, Sudhir

2012-08-01

Many perspectives on the role of evolution in human health include nonempirical assumptions concerning the adaptive evolutionary origins of human diseases. Evolutionary analyses of the increasing wealth of clinical and population genomic data have begun to challenge these presumptions. In order to systematically evaluate such claims, the time has come to build a common framework for an empirical and intellectual unification of evolution and modern medicine. We review the emerging evidence and provide a supporting conceptual framework that establishes the classical neutral theory of molecular evolution (NTME) as the basis for evaluating disease- associated genomic variations in health and medicine. For over a decade, the NTME has already explained the origins and distribution of variants implicated in diseases and has illuminated the power of evolutionary thinking in genomic medicine. We suggest that a majority of disease variants in modern populations will have neutral evolutionary origins (previously neutral), with a relatively smaller fraction exhibiting adaptive evolutionary origins (previously adaptive). This pattern is expected to hold true for common as well as rare disease variants. Ultimately, a neutral evolutionary perspective will provide medicine with an informative and actionable framework that enables objective clinical assessment beyond convenient tendencies to invoke past adaptive events in human history as a root cause of human disease.

VLA observations of circumnebular neutral hydrogen in IC 418

International Nuclear Information System (INIS)

Taylor, A.R.; Gussie, G.T.; Goss, W.M.

1989-01-01

Neutral hydrogen images of the planetary nebula IC 418 have been made with the Very Large Array. These images show H I emission and absorption in close association with the nebula. Assuming a distance of 1 kpc, the total mass of circumnebular neutral hydrogen is 0.35 + or - 0.05 solar mass. Model fits to the data indicate that the neutral gas falls as a 1/r-squared density distribution, with outflow velocity about 5 km/s less than the expansion rate of the ionized gas. The observations also indicate that there is a region devoid of H I emission between the outer edge of the H II nebula and the inner edge of the H I shell. It is suggested that this gap is comprised of molecular hydrogen and that the surrounding H I shell is produced by photodissociation of H2 by the interstellar radiation field. Physical parameters of the H I gas are derived. 25 refs

Plasma-neutral gas interaction in a tokamak divertor: effects of hydrogen molecules and plasma recombination

International Nuclear Information System (INIS)

Krasheninnikov, S.I.; Pigarov, A.Yu.; Soboleva, T.K.; Sigmar, D.J.

1997-01-01

We investigate the influence of hydrogen molecules on plasma recombination using a collisional-radiative model for multispecies hydrogen plasmas and tokamak detached divertor parameters. The rate constant found for molecular activated recombination of a plasma can be as high as 2 x 10 -10 cm 3 /s, confirming our pervious estimates. We investigate the effects of hydrogen molecules and plasma recombination on self-consistent plasma-neutral gas interactions in the recycling region of a tokamak divertor. We treat the plasma flow in a fluid approximation retaining the effects of plasma recombination and employing a Knudsen neutral transport model for a 'gas box' divertor geometry. For the model of plasma-neutral interactions we employ we find: (a) molecular activated recombination is a dominant channel of divertor plasma recombination; and (b) plasma recombination is a key element leading to a decrease in the plasma flux onto the target and substantial plasma pressure drop which are the main features of detached divertor regimes. (orig.)

Structures of phlebovirus glycoprotein Gn and identification of a neutralizing antibody epitope.

Science.gov (United States)

Wu, Yan; Zhu, Yaohua; Gao, Feng; Jiao, Yongjun; Oladejo, Babayemi O; Chai, Yan; Bi, Yuhai; Lu, Shan; Dong, Mengqiu; Zhang, Chang; Huang, Guangmei; Wong, Gary; Li, Na; Zhang, Yanfang; Li, Yan; Feng, Wen-Hai; Shi, Yi; Liang, Mifang; Zhang, Rongguang; Qi, Jianxun; Gao, George F

2017-09-05

Severe fever with thrombocytopenia syndrome virus (SFTSV) and Rift Valley fever virus (RVFV) are two arthropod-borne phleboviruses in the Bunyaviridae family, which cause severe illness in humans and animals. Glycoprotein N (Gn) is one of the envelope proteins on the virus surface and is a major antigenic component. Despite its importance for virus entry and fusion, the molecular features of the phleboviruse Gn were unknown. Here, we present the crystal structures of the Gn head domain from both SFTSV and RVFV, which display a similar compact triangular shape overall, while the three subdomains (domains I, II, and III) making up the Gn head display different arrangements. Ten cysteines in the Gn stem region are conserved among phleboviruses, four of which are responsible for Gn dimerization, as revealed in this study, and they are highly conserved for all members in Bunyaviridae Therefore, we propose an anchoring mode on the viral surface. The complex structure of the SFTSV Gn head and human neutralizing antibody MAb 4-5 reveals that helices α6 in subdomain III is the key component for neutralization. Importantly, the structure indicates that domain III is an ideal region recognized by specific neutralizing antibodies, while domain II is probably recognized by broadly neutralizing antibodies. Collectively, Gn is a desirable vaccine target, and our data provide a molecular basis for the rational design of vaccines against the diseases caused by phleboviruses and a model for bunyavirus Gn embedding on the viral surface.

Ro-vibrational laser spectroscopy of ESD neutrals from chemisorbed species

International Nuclear Information System (INIS)

Burns, A.R.; Stechel, E.B.; Jennison, D.R.

1987-01-01

Ever since the introduction of intense tunable laser radiation, the fields of molecular spectroscopy and dynamics have expanded tremendously. Indeed, with each technical improvement in laser resolution and output power, new applications have emerged with correspondingly increased levels of sophistication and information. In the field of electron-stimulated desorption (ESD), not only has the utilization of lasers resulted in the detection of neutral species, which were previously difficult to observe without specially-designed analyzers, but also the quantum-specific nature of the resonant laser interaction with the neutrals has yielded valuable information concerning internal energies. In this article, we will discuss some of the experimental methods in the application of laser resonance-ionization spectroscopy (RIS) to the study of the ESD of neutrals, in particular, chemisorbed NO and CO desorption from Pt(111). We will also show how the detailed information obtained in these experiments has identified a new desorption mechanism

Life History Traits, Protein Evolution, and the Nearly Neutral Theory in Amniotes.

Science.gov (United States)

Figuet, Emeric; Nabholz, Benoît; Bonneau, Manon; Mas Carrio, Eduard; Nadachowska-Brzyska, Krystyna; Ellegren, Hans; Galtier, Nicolas

2016-06-01

The nearly neutral theory of molecular evolution predicts that small populations should accumulate deleterious mutations at a faster rate than large populations. The analysis of nonsynonymous (dN) versus synonymous (dS) substitution rates in birds versus mammals, however, has provided contradictory results, questioning the generality of the nearly neutral theory. Here we analyzed the impact of life history traits, taken as proxies of the effective population size, on molecular evolutionary and population genetic processes in amniotes, including the so far neglected reptiles. We report a strong effect of species body mass, longevity, and age of sexual maturity on genome-wide patterns of polymorphism and divergence across the major groups of amniotes, in agreement with the nearly neutral theory. Our results indicate that the rate of protein evolution in amniotes is determined in the first place by the efficiency of purifying selection against deleterious mutations-and this is true of both radical and conservative amino acid changes. Interestingly, the among-species distribution of dN/dS in birds did not follow this general trend: dN/dS was not higher in large, long-lived than in small, short-lived species of birds. We show that this unexpected pattern is not due to a more narrow range of life history traits, a lack of correlation between traits and Ne, or a peculiar distribution of fitness effects of mutations in birds. Our analysis therefore highlights the bird dN/dS ratio as a molecular evolutionary paradox and a challenge for future research. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Influence of nonlinear effects on the neutral gas transport in tokamaks

International Nuclear Information System (INIS)

Behringer, T.

1992-06-01

The linear Monte Carlo computer code EIRENE for calculation of free molecular flow of neutral gases through a background plasma has been extended to the non-linear transition flow regime (Knudsen number 0.1-10). Motivation arose from higher gas densities in the range of 10 13 -10 15 cm -3 appearing in the srape-off layer and in parts of the vacuum system of advanced tokamak experiments. To treat the problem, the Direct Monte Carlo Simulation Method after Bird, a kinetic approach, was chosen, since the conditions for application of continuum theory are not met. First results with the extended code were obtained in calculating the conductance of plasma-free short cylindrical ducts and elbows. A steady increase in conductance with decreasing Knudsen number was found, which is in good agreement with experimental data. Further calculations for transition flows through fixed background plasmas were made. In these, solutions obtained were represented as differences from solutions obtained by linear calculations. Simulation of a 1-D plasma slab configuration (related to the gaseous divertor concept) revealed markedly varying neutral gas profiles due to neutral-neutral collisions. In addition, in these runs neutral-neutral inelastic collision processes turned out to be negligible. Finally, neutral gas behaviour at higher densities in pump limiter geometries was studied, related to experiments on the tokamak TEXTOR. An increase in conductance in the direction to the pumps of up to 25% relative to linear results was found. Recently obtained experimental data on the impact of non-linear neutral effects upon conductance could be confirmed. (orig.) [de

Detection of electrically neutral and nonpolar molecules in ionic solutions using silicon nanowires

Science.gov (United States)

Wu, Ying-Pin; Chu, Chia-Jung; Tsai, Li-Chu; Su, Ya-Wen; Chen, Pei-Hua; Moodley, Mathew K.; Huang, Ding; Chen, Yit-Tsong; Yang, Ying-Jay; Chen, Chii-Dong

2017-04-01

We report on a technique that can extend the use of nanowire sensors to the detection of interactions involving nonpolar and neutral molecules in an ionic solution environment. This technique makes use of the fact that molecular interactions result in a change in the permittivity of the molecules involved. For the interactions taking place at the surface of nanowires, this permittivity change can be determined from the analysis of the measured complex impedance of the nanowire. To demonstrate this technique, histidine was detected using different charge polarities controlled by the pH value of the solution. This included the detection of electrically neutral histidine at a sensitivity of 1 pM. Furthermore, it is shown that nonpolar molecules, such as hexane, can also be detected. The technique is applicable to the use of nanowires with and without a surface-insulating oxide. We show that information about the changes in amplitude and the phase of the complex impedance reveals the fundamental characteristics of the molecular interactions, including the molecular field and the permittivity.

Neutralization of feline immunodeficiency virus by polyclonal cat antibody: Simultaneous involvement of hypervariable regions 4 and 5 of the surface glycoprotein.

NARCIS (Netherlands)

C.H.J. Siebelink (Kees); W. Huisman (Willem); J.A. Karlas (Jos); G.F. Rimmelzwaan (Guus); M.L. Bosch (Marnix); A.D.M.E. Osterhaus (Albert)

1995-01-01

textabstractSites involved in antibody-mediated neutralization of feline immunodeficiency virus were mapped by reciprocal exchange of envelope fragments or amino acids between molecular clones of feline immunodeficiency virus with different susceptibilities to neutralization by a polyclonal cat

Search for an explanation for neutralization rates of atomic ion-ion reactions

Science.gov (United States)

Miller, Thomas M.; Wiens, Justin P.; Shuman, Nicholas S.; Viggiano, Albert A.

2016-09-01

We have measured well over a hundred rate coefficients k for cation-anion mutual neutralization reactions at thermal energies. For molecular ions, the k at 300 K tend not to vary more than a factor of two or three, presumably because a great many neutral states cross the incoming Coulombic potential energy curve. Atomic-atomic systems, for which there are few favorable curve crossings between the neutral and Coulombic curves, show variation of at least a factor of 60 in the measured k values at 300 K. For reactions involving the noble-gas cations, we assume that the final state is the lowest excited state of the neutral, plus the ground state of the neutralized anion, because otherwise the crossing distance R is so small that the curve-crossing probability is nil. We plotted measured k values (in cm3/s) vs the distance R (in bohr) at which the neutral and Coulombic curves cross, the found that the data are fairly well fit by a power law for k, 10-4R - 2 . 8 . The question is, is there a physical explanation for the observed dependence on R? We will discuss the data and the expectations of Landau-Zener theory. Supported by Air Force Office of Scientific Research (AFOSR-2303EP).

Climate Neutral Campus Key Terms and Definitions | Climate Neutral Research

Science.gov (United States)

Campuses | NREL Neutral Campus Key Terms and Definitions Climate Neutral Campus Key Terms and Definitions The term climate neutral evolved along with net zero and a number of other "green" and accuracy in these areas lets research campuses know exactly how close they are to climate

Evolution on neutral networks accelerates the ticking rate of the molecular clock.

Science.gov (United States)

Manrubia, Susanna; Cuesta, José A

2015-01-06

Large sets of genotypes give rise to the same phenotype, because phenotypic expression is highly redundant. Accordingly, a population can accept mutations without altering its phenotype, as long as the genotype mutates into another one on the same set. By linking every pair of genotypes that are mutually accessible through mutation, genotypes organize themselves into neutral networks (NNs). These networks are known to be heterogeneous and assortative, and these properties affect the evolutionary dynamics of the population. By studying the dynamics of populations on NNs with arbitrary topology, we analyse the effect of assortativity, of NN (phenotype) fitness and of network size. We find that the probability that the population leaves the network is smaller the longer the time spent on it. This progressive 'phenotypic entrapment' entails a systematic increase in the overdispersion of the process with time and an acceleration in the fixation rate of neutral mutations. We also quantify the variation of these effects with the size of the phenotype and with its fitness relative to that of neighbouring alternatives. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Neutrality Versus Materiality: A Thermodynamic Theory of Neutral Surfaces

Directory of Open Access Journals (Sweden)

Rémi Tailleux

2016-09-01

Full Text Available In this paper, a theory for constructing quasi-neutral density variables γ directly in thermodynamic space is formulated, which is based on minimising the absolute value of a purely thermodynamic quantity J n . Physically, J n has a dual dynamic/thermodynamic interpretation as the quantity controlling the energy cost of adiabatic and isohaline parcel exchanges on material surfaces, as well as the dependence of in-situ density on spiciness, in a description of water masses based on γ, spiciness and pressure. Mathematically, minimising | J n | in thermodynamic space is showed to be equivalent to maximising neutrality in physical space. The physics of epineutral dispersion is also reviewed and discussed. It is argued, in particular, that epineutral dispersion is best understood as the aggregate effect of many individual non-neutral stirring events (being understood here as adiabatic and isohaline events with non-zero buoyancy, so that it is only the net displacement aggregated over many events that is approximately neutral. This new view resolves an apparent paradox between the focus in neutral density theory on zero-buoyancy motions and the overwhelming evidence that lateral dispersion in the ocean is primarily caused by non-zero buoyancy processes such as tides, residual currents and sheared internal waves. The efficiency by which a physical process contributes to lateral dispersion can be characterised by its energy signature, with those processes releasing available potential energy (negative energy cost being more efficient than purely neutral processes with zero energy cost. The latter mechanism occurs in the wedge of instability, and its source of energy is the coupling between baroclinicity, thermobaricity, and density compensated temperature/salinity anomalies. Such a mechanism, which can only exist in a salty ocean, is speculated to be important for dissipating spiciness anomalies and neutral helicity. The paper also discusses potential

Structure-function analyses reveal the molecular architecture and neutralization mechanism of a bacterial HEPN-MNT toxin-antitoxin system.

Science.gov (United States)

Jia, Xuanyan; Yao, Jianyun; Gao, Zengqiang; Liu, Guangfeng; Dong, Yu-Hui; Wang, Xiaoxue; Zhang, Heng

2018-05-04

Toxin-antitoxin (TA) loci in bacteria are small genetic modules that regulate various cellular activities, including cell growth and death. The two-gene module encoding a HEPN (higher eukaryotes and prokaryotes nucleotide-binding) domain and a cognate MNT (minimal nucleotidyltransferase) domain have been predicted to represent a novel type II TA system prevalent in archaea and bacteria. However, the neutralization mechanism and cellular targets of the TA family remain unclear. The toxin SO_3166 having a HEPN domain and its cognate antitoxin SO_3165 with an MNT domain constitute a typical type II TA system that regulates cell motility and confers plasmid stability in the bacterium Shewanella oneidensis Here, we report the crystal structure and solution conformation of the SO_3166-SO_3165 pair, representing the first complex structures in this TA family. The structures revealed that SO_3165 and SO_3166 form a tight heterooctamer (at a 2:6 ratio), an organization that is very rare in other TA systems. We also observed that SO_3166 dimerization enables the formation of a deep cleft at the HEPN-domain interface harboring a composite R X 4-6H active site that functions as an RNA-cleaving RNase. SO_3165 bound SO_3166 mainly through its two α-helices (α2 and α4), functioning as molecular recognition elements. Moreover, their insertion into the SO_3166 cleft sterically blocked the R X 4-6H site or narrowed the cleft to inhibit RNA substrate binding. Structure-based mutagenesis confirmed the important roles of these α-helices in SO_3166 binding and inhibition. Our structure-function analysis provides first insights into the neutralization mechanism of the HEPN-MNT TA family. © 2018 Jia et al.

Understanding Molecular-Ion Neutral Atom Collisions for the Production of Ultracold Molecular Ions

Science.gov (United States)

2014-02-03

SECURITY CLASSIFICATION OF: This project was superseded and replaced by another ARO-funded project of the same name, which is still continuing. The goal...cooled atoms," IOTA -COST Workshop on molecular ions, Arosa, Switzerland. 5. E.R. Hudson, "Sympathetic cooling of molecules with laser cooled

Modeling of the lithium based neutralizer for ITER neutral beam injector

Energy Technology Data Exchange (ETDEWEB)

Dure, F., E-mail: franck.dure@u-psud.fr [LPGP, Laboratoire de Physique des Gaz et Plasmas, CNRS-Universite Paris Sud, Orsay (France); Lifschitz, A.; Bretagne, J.; Maynard, G. [LPGP, Laboratoire de Physique des Gaz et Plasmas, CNRS-Universite Paris Sud, Orsay (France); Simonin, A. [IRFM, Institut de Recherche sur la Fusion Magnetique, CEA Cadarache, 13108 Saint-Paul lez Durance (France); Minea, T. [LPGP, Laboratoire de Physique des Gaz et Plasmas, CNRS-Universite Paris Sud, Orsay (France)

2012-04-04

Highlights: Black-Right-Pointing-Pointer We compare different lithium based neutraliser configurations to the deuterium one. Black-Right-Pointing-Pointer We study characteristics of the secondary plasma and the propagation of the 1 MeV beam. Black-Right-Pointing-Pointer Using lithium increases the neutralisation effiency keeping correct beam focusing. Black-Right-Pointing-Pointer Using lithium also reduces the backstreaming effect in direction of the ion source. - Abstract: To achieve thermonuclear temperatures necessary to produce fusion reactions in the ITER Tokamak, additional heating systems are required. One of the main method to heat the plasma ions in ITER will be the injection of energetic neutrals (NBI). In the neutral beam injector, negative ions (D{sup -}) are electrostatically accelerated to 1 MeV, and then stripped of their extra electron via collisions with a target gas, in a structure known as neutralizer. In the current ITER specification, the target gas is deuterium. It has been recently proposed to use lithium vapor instead of deuterium as target gas in the neutralizer. This would allow to reduce the gas load in the NBI vessel and to improve the neutralization efficiency. A Particle-in-Cell Monte Carlo code has been developed to study the transport of the beams and the plasma formation in the neutralizer. A comparison between Li and D{sub 2} based neutralizers made with this code is presented here, as well as a parametric study on the geometry of the Li based neutralizer. Results demonstrate the feasibility of a Li based neutralizer, and its advantages with respect to the deuterium based one.

Molecular Basis for the Neutralization of Tumor Necrosis Factor α by Certolizumab Pegol in the Treatment of Inflammatory Autoimmune Diseases

Directory of Open Access Journals (Sweden)

Jee Un Lee

2017-01-01

Full Text Available Monoclonal antibodies against TNFα, including infliximab, adalimumab, golimumab, and certolizumab pegol, are widely used for the treatment of the inflammatory diseases such as rheumatoid arthritis and inflammatory bowel disease. Recently, the crystal structures of TNFα, in complex with the Fab fragments of infliximab and adalimumab, have revealed the molecular mechanisms of these antibody drugs. Here, we report the crystal structure of TNFα in complex with the Fab fragment of certolizumab pegol to clarify the precise antigen-antibody interactions and the structural basis for the neutralization of TNFα by this therapeutic antibody. The structural analysis and the mutagenesis study revealed that the epitope is limited to a single protomer of the TNFα trimer. Additionally, the DE loop and the GH loop of TNFα play critical roles in the interaction with certolizumab, suggesting that this drug exerts its effects by partially occupying the receptor binding site of TNFα. In addition, a conformational change of the DE loop was induced by certolizumab binding, thereby interrupting the TNFα-receptor interaction. A comprehensive comparison of the interactions of TNFα blockers with TNFα revealed the epitope diversity on the surface of TNFα, providing a better understanding of the molecular mechanism of TNFα blockers. The accumulation of these structural studies can provide a basis for the improvement of therapeutic antibodies against TNFα.

Natural selection constrains neutral diversity across a wide range of species.

Science.gov (United States)

Corbett-Detig, Russell B; Hartl, Daniel L; Sackton, Timothy B

2015-04-01

The neutral theory of molecular evolution predicts that the amount of neutral polymorphisms within a species will increase proportionally with the census population size (Nc). However, this prediction has not been borne out in practice: while the range of Nc spans many orders of magnitude, levels of genetic diversity within species fall in a comparatively narrow range. Although theoretical arguments have invoked the increased efficacy of natural selection in larger populations to explain this discrepancy, few direct empirical tests of this hypothesis have been conducted. In this work, we provide a direct test of this hypothesis using population genomic data from a wide range of taxonomically diverse species. To do this, we relied on the fact that the impact of natural selection on linked neutral diversity depends on the local recombinational environment. In regions of relatively low recombination, selected variants affect more neutral sites through linkage, and the resulting correlation between recombination and polymorphism allows a quantitative assessment of the magnitude of the impact of selection on linked neutral diversity. By comparing whole genome polymorphism data and genetic maps using a coalescent modeling framework, we estimate the degree to which natural selection reduces linked neutral diversity for 40 species of obligately sexual eukaryotes. We then show that the magnitude of the impact of natural selection is positively correlated with Nc, based on body size and species range as proxies for census population size. These results demonstrate that natural selection removes more variation at linked neutral sites in species with large Nc than those with small Nc and provides direct empirical evidence that natural selection constrains levels of neutral genetic diversity across many species. This implies that natural selection may provide an explanation for this longstanding paradox of population genetics.

Constraints on extra dimensions from precision molecular spectroscopy

NARCIS (Netherlands)

Salumbides, E.J.; Schellekens, A.N.; Gato-Rivera, B.; Ubachs, W.M.G.

2015-01-01

Accurate investigations of quantum-level energies in molecular systems are shown to provide a testing ground to constrain the size of compactified extra dimensions. This is made possible by recent progress in precision metrology with ultrastable lasers on energy levels in neutral molecular hydrogen

Transient currents in a molecular photo-diode

OpenAIRE

Petrov, E. G.; Leonov, V. O.; May, V.; Hänggi, P.

2012-01-01

Light-induced charge transmission through a molecular junction (molecular diode) is studied in the framework of a HOMO-LUMO model and in using a kinetic description. Expressions are presented for the sequential (hopping) and direct (tunneling) transient current components together with kinetic equations governing the time-dependent populations of the neutral and charged molecular states which participate in the current formation. Resonant and off-resonant charge transmission processes are ana...

New concepts for molecular magnets

Science.gov (United States)

Pilawa, Bernd

1999-03-01

Miller and Epstein (1994) define molecular magnets as magnetic materials which are prepared by the low-temperature methods of the preparative chemistry. This definition includes molecular crystals of neutral radicals, radical salts and charge transfer complexes as well as metal complexes and polymers with unpaired spins (Dormann 1995). The challenge of molecular magnets consists in tailoring magnetic properties by specific modifications of the molecular units. The combination of magnetism with mechanical or electrical properties of molecular compounds promise materials of high technical interest (Gatteschi 1994a and 1994b, Möhwald 1996) and both the chemical synthesis of new molecular materials with magnetic properties as well as the physical investigation and explanation of these properties is important, in order to achieve any progress. This work deals with the physical characterization of the magnetic properties of molecular materials. It is organized as follows. In the first part molecular crystals of neutral radicals are studied. After briefly discussing the general magnetic properties of these materials and after an overview over the physical principles of exchange interaction between organic radicals I focus on the interplay between the crystallographic structure and the magnetic properties of various derivatives of the verdazyl and nitronyl nitroxide radicals. The magnetic properties of metal complexes are the subject of the second part. After an overview over the experimental and theoretical tools which are used for the investigation of the magnetic properties I shortly discuss the exchange coupling of transition metal ions and the magnetic properties of complexes of two and three metal ions. Special emphasis is given to spin cluster compounds. Spin cluster denote complexes of many magnetic ions. They are attractive as building blocks of molecular magnets as well as magnetic model compounds for the study of spin frustration, molecular super

Neutral mutation as the source of genetic variation in life history traits.

Science.gov (United States)

Brcić-Kostić, Krunoslav

2005-08-01

The mechanism underlying the maintenance of adaptive genetic variation is a long-standing question in evolutionary genetics. There are two concepts (mutation-selection balance and balancing selection) which are based on the phenotypic differences between alleles. Mutation - selection balance and balancing selection cannot properly explain the process of gene substitution, i.e. the molecular evolution of quantitative trait loci affecting fitness. I assume that such loci have non-essential functions (small effects on fitness), and that they have the potential to evolve into new functions and acquire new adaptations. Here I show that a high amount of neutral polymorphism at these loci can exist in real populations. Consistent with this, I propose a hypothesis for the maintenance of genetic variation in life history traits which can be efficient for the fixation of alleles with very small selective advantage. The hypothesis is based on neutral polymorphism at quantitative trait loci and both neutral and adaptive gene substitutions. The model of neutral - adaptive conversion (NAC) assumes that neutral alleles are not neutral indefinitely, and that in specific and very rare situations phenotypic (relative fitness) differences between them can appear. In this paper I focus on NAC due to phenotypic plasticity of neutral alleles. The important evolutionary consequence of NAC could be the increased adaptive potential of a population. Loci responsible for adaptation should be fast evolving genes with minimally discernible phenotypic effects, and the recent discovery of genes with such characteristics implicates them as suitable candidates for loci involved in adaptation.

Study of neutral particles

International Nuclear Information System (INIS)

Bartel, W.; Bulos, F.; Eisner, A.

1975-01-01

The range of physics problems for which a detector emphasizing neutrals is most suitable is discussed. The primary goals are the all neutrals cross section, sigma/sub o/ (e + e - → neutrals), the characterization of the neutral energy in multi-hadronic events, the search for monoenergetic photons, and good sensitivity in the difficult region of low energy photons. Those features of multi-hadronic events which are most relevant to a neutral detector were calculated using a jet model with parameters extrapolated from SPEAR energies. These distributions are presented and discussed

A novel mutation in PNPLA2 leading to neutral lipid storage disease with myopathy.

Science.gov (United States)

Ash, Daniel B; Papadimitriou, Dimitra; Hays, Arthur P; Dimauro, Salvatore; Hirano, Michio

2012-09-01

Mutations in PNPLA2, a gene encoding adipose triglyceride lipase, lead to neutral lipid storage disease with myopathy. To report the clinical and molecular features of a case of neutral lipid storage disease with myopathy resulting from a novel mutation in PNPLA2. Case report. University hospital. A 65-year-old man with progressive muscle weakness and high serum creatine kinase levels. Direct sequencing of the PNPLA2 gene. Identification of a novel homozygous mutation in the patient's PNPLA2 gene confirmed the suspected diagnosis of neutral lipid storage disease with myopathy. Screening of the PNPLA2 gene should be considered for patients presenting with high levels of creatine kinase, progressive muscle weakness, and systemic lipid accumulation. The presence of Jordans anomaly can be a strong diagnostic clue.

Neutral beam monitoring

International Nuclear Information System (INIS)

Fink, J.H.

1979-01-01

A neutral beam generated by passing accelerated ions through a walled cell containing a low energy neutral gas, such that charge exchange partially neutralizes the high energy beam, is monitored by detecting the current flowing through the cell wall produced by low energy ions which drift to the wall after the charge exchange. By segmenting the wall into radial and longitudinal segments various beam conditions are identified. (U.K.)

Bunched beam neutralization

International Nuclear Information System (INIS)

Gammel, G.M.; Maschke, A.W.; Mobley, R.M.

1979-01-01

One of the steps involved in producing an intense ion beam from conventional accelerators for Heavy Ion Fusion (HIF) is beam bunching. To maintain space charge neutralized transport, neutralization must occur more quickly as the beam bunches. It has been demonstrated at BNL that a 60 mA proton beam from a 750 kV Cockcroft--Walton can be neutralized within a microsecond. The special problem in HIF is that the neutralization must occur in a time scale of nanoseconds. To study neutralization on a faster time scale, a 40 mA, 450 kV proton beam was bunched at 16 MHz. A biased Faraday cup sampled the bunched beam at the position where maximum bunching was nominally expected, about 2.5 meters from the buncher. Part of the drift region, about 1.8 meters, was occupied by a series of Gabor lenses. In addition to enhancing beam transport by transverse focussing, the background cloud of electrons in the lenses provided an extra degree of neutralization. With no lens, the best bunch factor was at least 20. Bunch factor is defined here as the ratio of the distance between bunches to the FWHM bunch length. With the lens, it was hoped that the increased plasma frequency would decrease the neutralization time and cause an increase in the bunch factor. In fact, with the lens, the instantaneous current increased about three times, but the bunch factor dropped to about 10. Even with the lens, the FWHM of the bunches at the position of maximum bunching was still comparable to or less than the oscillation period of the surrounding electron plasma. Thus, the electron density in the lens must increase before neutralization could be effective in this case, or bunching should be done at a lower frequency

Understanding Molecular Ion-Neutral Atom Collisions for the Production of Ultracold Molecular Ions

Science.gov (United States)

2016-06-06

2012): 0. doi: 10.1103/PhysRevLett.109.223002 Kuang Chen, Scott T. Sullivan, Wade G. Rellergert, Eric R. Hudson. Measurement of the Coulomb Logarithm...or fellowships for further studies in science, mathematics, engineering or technology fields: Student Metrics This section only applies to graduating...clouds of Ba+ ions and Ca atoms. Due to the strong Coulomb interaction, the Ba+ ions quickly cool the molecular ion translation motion, while the

Electron-impact excitation of molecular ions

International Nuclear Information System (INIS)

Neufeld, D.A.; Dalgarno, A.

1989-01-01

A simple expression is derived that relates the rate coefficient for dipole-allowed electron-impact excitation of a molecular ion in the Coulomb-Born approximation to the Einstein A coefficient for the corresponding radiative decay. Results are given for several molecular ions of astrophysical interest. A general analytic expression is obtained for the equilibrium rotational level populations in the ground vibrational state of any molecular ion excited by collisions with electrons. The expression depends only upon the electron temperature, the electron density, and the rotational constant of the molecular ion. A similar expression is obtained for neutral polar molecules

An electrostatic elliptical mirror for neutral polar molecules.

Science.gov (United States)

González Flórez, A Isabel; Meek, Samuel A; Haak, Henrik; Conrad, Horst; Santambrogio, Gabriele; Meijer, Gerard

2011-11-14

Focusing optics for neutral molecules finds application in shaping and steering molecular beams. Here we present an electrostatic elliptical mirror for polar molecules consisting of an array of microstructured gold electrodes deposited on a glass substrate. Alternating positive and negative voltages applied to the electrodes create a repulsive potential for molecules in low-field-seeking states. The equipotential lines are parallel to the substrate surface, which is bent in an elliptical shape. The mirror is characterized by focusing a beam of metastable CO molecules and the results are compared to the outcome of trajectory simulations.

Mössbauer spectroscopy of ZnxMg1-x Fe2O4 (0 ≤ x ≤ 0.74) nanostructures crystallized from borate glasses

Science.gov (United States)

El Shabrawy, S.; Miglierini, M.; Schaaf, P.; Tzankov, D.; Georgieva, M.; Harizanova, R.; Rüssel, C.

2018-03-01

Glasses in the system 51.7 B2O3/9.3 K2O/1 P2O5/10.4 Fe2O3/(27.6 - y) MgO/y ZnO (with y = 0, 1, 2.5, 5, 7.5, 10, 13.8, and 20) were prepared by the conventional melt quenching method. The glass samples were thermally treated at 560 °C for 3 h in ambient conditions. Using 57Fe Mössbauer spectroscopy, the effect of the substitution of MgO by ZnO in the glass network and the effect on the precipitated crystallized phase was studied. The results showed that the ratio of Zn2+:Mg2+ in the precipitated crystals increases with the ZnO concentration in the glass. The isomer shift values indicated that iron occurs as Fe3+, which is distributed at the tetrahedral (A) and the octahedral [B] sites. Introducing ZnO leads to a relative increase of the Fe3+ concentration at the B sites at the expense of that occupying the A sites. This indicates the precipitation of ZnxMg1-x Fe2O4 nanoparticles, where Zn2+ ions favorably occupy the A sites. The average hyperfine field of the samples showed a strong dependence on the Zn concentration. At the highest Zn concentration of 13.8 and 20 mol%, the samples are paramagnetic, while for the smaller ones, the samples are superparamagnetic.

Estimating Collisionally-Induced Escape Rates of Light Neutrals from Early Mars

Science.gov (United States)

Gacesa, M.; Zahnle, K. J.

2016-12-01

Collisions of atmospheric gases with hot oxygen atoms constitute an important non-thermal mechanism of escape of light atomic and molecular species at Mars. In this study, we present revised theoretical estimates of non-thermal escape rates of neutral O, H, He, and H2 based on recent atmospheric density profiles obtained from the NASA Mars Atmosphere and Volatile Evolution (MAVEN) mission and related theoretical models. As primary sources of hot oxygen, we consider dissociative recombination of O2+ and CO2+ molecular ions. We also consider hot oxygen atoms energized in primary and secondary collisions with energetic neutral atoms (ENAs) produced in charge-exchange of solar wind H+ and He+ ions with atmospheric gases1,2. Scattering of hot oxygen and atmospheric species of interest is modeled using fully-quantum reactive scattering formalism3. This approach allows us to construct distributions of vibrationally and rotationally excited states and predict the products' emission spectra. In addition, we estimate formation rates of excited, translationally hot hydroxyl molecules in the upper atmosphere of Mars. The escape rates are calculated from the kinetic energy distributions of the reaction products using an enhanced 1D model of the atmosphere for a range of orbital and solar parameters. Finally, by considering different scenarios, we estimate the influence of these escape mechanisms on the evolution of Mars's atmosphere throughout previous epochs and their impact on the atmospheric D/H ratio. M.G.'s research was supported by an appointment to the NASA Postdoctoral Program at the NASA Ames Research Center, administered by Universities Space Research Association under contract with NASA. 1N. Lewkow and V. Kharchenko, "Precipitation of Energetic Neutral Atoms and Escape Fluxes induced from the Mars Atmosphere", Astroph. J., 790, 98 (2014) 2M. Gacesa, N. Lewkow, and V. Kharchenko, "Non-thermal production and escape of OH from the upper atmosphere of Mars", arXiv:1607

Subauroral Ion-neutral Coupling During the March 2015 Superstorm

Science.gov (United States)

Zhang, S.; Erickson, P. J.; Foster, J. C.; Holt, J. M.; Coster, A. J.; Makela, J. J.; Noto, J.; Meriwether, J. W.; Otsuka, Y.; Nicolls, M. J.; McCready, M. A.

2015-12-01

The arrival of solar Coronal Mass Ejection materials overlapping a high-speed solar wind stream originated from a nearby coronal hole caused huge magnetic disturbances during March 17-18, 2015. We have coordinated an international campaign to monitor their geospace effects using ground-based facilities, including incoherent scatter radars and Fabry-Perot Interferometers in the America sectors and other instruments in East Asia sectors, forming an observational network along approximately the 60W/120E meridional circle. The presentation will provide highlights of these observations, with a focus on the ion-neutral coupling processes at subauroral and mid-latitudes. One of the most stiking findings is the northward neutral wind surge, observed in multiple sites, accompanying strong westward winds developed at earlier times. We ascribe this unexpected wind disturbances to Subauroal Polarization Stream (SAPS) asscoated strong plasma flows driving ion-neutral coupling. SAPS and strong ion flow were observed by Millstone Hill ISR and DMSP in situ measurements. We will also report the Millstone Hill ISR observations of a significant enhancement in the storm-time molecular ion composition in the F1-region height. This enhancement appears to be caused by strong vertical ion drift due to penetration electric fields.

Neutralized transport experiment

International Nuclear Information System (INIS)

Roy, P.K.; Yu, S.S.; Eylon, S.; Henestroza, E.; Anders, A.; Gilson, E.P.; Bieniosek, F.M.; Greenway, W.G.; Logan, B.G.; Waldron, W.L.; Shuman, D.B.; Vanecek, D.L.; Welch, D.R.; Rose, D.V.; Thoma, C.; Davidson, R.C.; Efthimion, P.C.; Kaganovich, I.; Sefkow, A.B.; Sharp, W.M.

2005-01-01

Experimental details on providing active neutralization of high brightness ion beam have been demonstrated for Heavy Ion Fusion program. A K + beam was extracted from a variable-perveance injector and transported through 2.4 m long quadrupole lattice for final focusing. Neutralization was provided by a localized cathode arc plasma plug and a RF volume plasma system. Effects of beam perveance, emittance, convergence focusing angle, and axial focusing position on neutralization have been investigated. Good agreement has been observed with theory and experiment throughout the study

A neutral sampling formula for multiple samples and an `exact' test of neutrality

NARCIS (Netherlands)

Etienne, R.S.

2007-01-01

As the utility of the neutral theory of biodiversity is increasingly being recognized, there is also an increasing need for proper tools to evaluate the relative importance of neutral processes (dispersal limitation and stochasticity). One of the key features of neutral theory is its close link to

A neutral sampling formula for multiple samples and an 'exact' test of neutrality

NARCIS (Netherlands)

Etienne, Rampal S.

As the utility of the neutral theory of biodiversity is increasingly being recognized, there is also an increasing need for proper tools to evaluate the relative importance of neutral processes (dispersal limitation and stochasticity). One of the key features of neutral theory is its close link to

Search for neutral leptons

International Nuclear Information System (INIS)

Perl, M.L.

1984-12-01

At present we know of three kinds of neutral leptons: the electron neutrino, the muon neutrino, and the tau neutrino. This paper reviews the search for additional neutral leptons. The method and significance of a search depends upon the model used for the neutral lepton being sought. Some models for the properties and decay modes of proposed neutral leptons are described. Past and present searches are reviewed. The limits obtained by some completed searches are given, and the methods of searches in progress are described. Future searches are discussed. 41 references

Neutral currents

International Nuclear Information System (INIS)

Paschos, E.A.

1977-01-01

It is stated that over the past few years considerable progress has been made in the field of weak interactions. The existence of neutral currents involving leptons and hadrons has been established and some of the questions concerning their detailed structure have been answered. This imposes constraints on the gauge theories and has eliminated large classes of models. New questions have also been raised, one of which concerns the conservation laws obeyed by neutral currents. The wide range of investigations is impressive and is expected to continue with new results from particle, nuclear, and atomic physics. Headings include - various aspects of a gauge theory (choice of group, the symmetry breaking scheme, representation assignments for fermion fields); space-time structure; isospin structure; leptonic neutral currents; and atomic experiments. (U.K.)

Molecules in the cold environment of a supersonic free-jet beam: from spectroscopy of neutral-neutral interactions to a test of Bell's inequality

International Nuclear Information System (INIS)

Koperski, J; Fry, E S

2006-01-01

The supersonic free-jet expansion technique has been used in different fields of research in physics, physical chemistry and chemistry to study vibrational and rotational molecular structures in ground and excited electronic energy states as well as in cold chemistry to study chemical reactions in a unique environment. The supersonic beam technique, as a widely used method in laser spectroscopy of molecules, exploits a source of monokinetic, rotationally and vibrationally cold molecules, that are very weakly bound in their ground electronic states (van der Waals molecules). In experiments at Jagiellonian University the supersonic free-jet beam serves as a source of ground-state van der Waals objects in studies of neutral-neutral interactions between group 12 metal (M = Zn, Cd, Hg) and noble gas (NG) atoms. Recently, the method has been applied as a source of entangled 199 Hg atom pairs in order to test Bell's inequality in an experiment at Texas A and M University

Fixations of the HIV-1 env gene refute neutralism: New evidence for pan-selective evolution

Directory of Open Access Journals (Sweden)

Carlos Y Valenzuela

2010-01-01

Full Text Available We examined 103 nucleotide sequences of the HIV-1 env gene, sampled from 35 countries and tested: I the random (neutral distribution of the number of nucleotide changes; II the proportion of bases at molecular equilibrium; III the neutral expected homogeneity of the distribution of new fxated bases; IV the hypothesis of the neighbor infuence on the mutation rates in a site. The expected random number of fxations per site was estimated by Bose-Einstein statistics, and the expected frequencies of bases by matrices of mutation-fxation rates. The homogeneity of new fxations was analyzed using χ2 and trinomial tests for homogeneity. Fixations of the central base in trinucleotides were used to test the neighbor infuence on base substitutions. Neither the number of fxations nor the frequencies of bases ftted the expected neutral distribution. There was a highly signifcant heterogeneity in the distribution of new fxations, and several sites showed more transversions than transitions, showing that each nucleotide site has its own pattern of change. These three independent results make the neutral theory, the nearly neutral and the neighbor infuence hypotheses untenable and indicate that evolution of env is rather highly selective.

Comparative measurement of the neutral density and particle confinement time in EBT

International Nuclear Information System (INIS)

Glowienka, J.C.; Richards, R.K.

1985-11-01

The neutral density and particle confinement time in the ELMO Bumpy Torus-Scale Experiment (EBT-S) have been determined by two different techniques. These involve a spectroscopic measurement of molecular and atomic hydrogen emissions and a time-decay measurement of a fast-ion population using a diagnostic neutral beam. The results from both diagnostics exhibit identical trends for either estimate, although the absolute values differ by a factor of 2 to 3. The observed variations with fill gas pressure and microwave power from either technique are consistent with measurements of electron density and temperature. In this paper, the measurement techniques are discussed, and the results are compared in the context of consistency with independently observed plasma behavior. 6 refs., 7 figs

Two different mutations in the envelope protein of feline immunodeficiency virus allow the virus to escape from neutralization by feline serum antibodies.

NARCIS (Netherlands)

C.H.J. Siebelink (Kees); M.L. Bosch (Marnix); G.F. Rimmelzwaan (Guus); R.H. Meloen; A.D.M.E. Osterhaus (Albert)

1995-01-01

textabstractViral progeny of two molecular clones of feline immunodeficiency virus (FIV), 19k1 and 19k32, were tested in a virus neutralization assay. In this assay the infection of thymocytes with FIV19k1 was neutralized by serum S1422, derived from an SPF cat 22 weeks after infection with FIV19k1.

STABILIZATION OF THE NEUTRAL PROTEASE OF BACILLUS-STEAROTHERMOPHILUS BY REMOVAL OF A BURIED WATER MOLECULE

NARCIS (Netherlands)

VRIEND, G; BERENDSEN, HJC; VANDERZEE, [No Value; VANDENBURG, B; VENEMA, G; EIJSINK, VGH

1991-01-01

Using site-directed mutagenesis, Ala166 in the neutral protease of Bacillus stearothermophilus was changed into Ser. Model building and molecular dynamics simulations of the mutant enzyme indicated that the Ser hydroxyl group fits well in a cavity which contains a water molecule in the wild-type

Atomic and molecular hydrogen gas temperatures in a low-pressure helicon plasma

Science.gov (United States)

Samuell, Cameron M.; Corr, Cormac S.

2015-08-01

Neutral gas temperatures in hydrogen plasmas are important for experimental and modelling efforts in fusion technology, plasma processing, and surface modification applications. To provide values relevant to these application areas, neutral gas temperatures were measured in a low pressure (radiofrequency helicon discharge using spectroscopic techniques. The atomic and molecular species were not found to be in thermal equilibrium with the atomic temperature being mostly larger then the molecular temperature. In low power operation (measurements near a graphite target demonstrated localised cooling near the sample surface. The temporal evolution of the molecular gas temperature during a high power 1.1 ms plasma pulse was also investigated and found to vary considerably as a function of pressure.

Protein Nanopore-Based Discrimination between Selected Neutral Amino Acids from Polypeptides.

Science.gov (United States)

Asandei, Alina; Rossini, Aldo E; Chinappi, Mauro; Park, Yoonkyung; Luchian, Tudor

2017-12-19

Nanopore probing of biological polymers has the potential to achieve single-molecule sequencing at low cost, high throughput, portability, and minimal sample preparation and apparatus. In this article, we explore the possibility of discrimination between neutral amino acid residues from the primary structure of 30 amino acids long, engineered peptides, through the analysis of single-molecule ionic current fluctuations accompanying their slowed-down translocation across the wild type α-hemolysin (α-HL) nanopore, and molecular dynamics simulations. We found that the transient presence inside the α-HL of alanine or tryptophan residues from the primary sequence of engineered peptides results in distinct features of the ionic current fluctuation pattern associated with the peptide reversibly blocking the nanopore. We propose that α-HL sensitivity to the molecular exclusion at the most constricted region mediates ionic current blockade events correlated with the volumes that are occluded by at least three alanine or tryptophan residues, and provides the specificity needed to discriminate between groups of neutral amino acids. Further, we find that the pattern of current fluctuations depends on the orientation of the threaded amino acid residues, suggestive of a conformational anisotropy of the ensemble of conformations of the peptide on the restricted nanopore region, related to its relative axial orientation inside the nanopore.

Plasma neutralizer for H- beams

International Nuclear Information System (INIS)

Grossman, M.W.

1977-01-01

Neutralization of H - beams by a hydrogen plasma is discussed. Optimum target thickness and maximum neutralization efficiency as a function of the fraction of the hydrogen target gas ionized is calculated for different H - beam energies. Also, the variation of neutralization efficiency with respect to target thickness for different H - beam energies is computed. The dispersion of the neutralized beam by a magnetic field for different energies and different values of B . z is found. Finally, a type of plasma jet is proposed, which may be suitable for a compact H - neutralizer

Glycosylation analysis of recombinant neutral protease I from Aspergillus oryzae expressed in Pichia pastoris.

Science.gov (United States)

Lei, Da; Xu, Yang; He, Qinghua; Pang, Yifeng; Chen, Bo; Xiong, Liang; Li, Yanping

2013-12-01

Neutral protease I from Aspergillus oryzae 3.042 was expressed in Pichia pastoris and its N-glycosylation properties were analyzed. After purification by nickel-affinity chromatography column, the recombinant neutral protease (rNPI) was confirmed to be N-glycosylated by periodicacid/Schiff's base staining and Endo H digestion. Moreover, the deglycosylated protein's molecular weight decreased to 43.3 kDa from 54.5 kDa analyzed by SDS-PAGE and MALDI-TOF-MS, and the hyperglycosylation extent was 21 %. The N-glycosylation site of rNPI was analyzed by nano LC-MS/MS after digesting by trypsin and Glu-C, and the unique potential site Asn41 of mature peptide was found to be glycosylated. Homology modeling of the 3D structure of rNPI indicated that the attached N-glycans hardly affected neutral protease's activity due to the great distance away from the active site of the enzyme.

Neutralization escape mutants define a dominant immunogenic neutralization site on hepatitis A virus

International Nuclear Information System (INIS)

Stapleton, J.T.; Lemon, S.M.

1987-01-01

Hepatitis A virus is an hepatotrophic human picornavirus which demonstrates little antigenic variability. To topologically map immunogenic sites on hepatitis A virus which elicit neutralizing antibodies, eight neutralizing monoclonal antibodies were evaluated in competition immunoassays employing radiolabeled monoclonal antibodies and HM-175 virus. Whereas two antibodies (K3-4C8 and K3-2F2) bound to intimately overlapping epitopes, the epitope bound by a third antibody (B5-B3) was distinctly different as evidenced by a lack of competition between antibodies for binding to the virus. The other five antibodies variably blocked the binding of both K3-4C8-K3-2F2 and B5-B3, suggesting that these epitopes are closely spaced and perhaps part of a single neutralization immunogenic site. Several combinations of monoclonal antibodies blocked the binding of polyclonal human convalescent antibody by greater than 96%, indicating that the neutralization epitopes bound by these antibodies are immunodominant in humans. Spontaneously arising HM-175 mutants were selected for resistance to monoclonal antibody-mediated neutralization. Neutralization resistance was associated with reduced antibody binding. These results suggest that hepatitis A virus may differ from poliovirus in possessing a single, dominant neutralization immunogenic site and therefore may be a better candidate for synthetic peptide or antiidiotype vaccine development

INCREASING THE THERMOSTABILITY OF THE NEUTRAL PROTEINASE OF BACILLUS-STEAROTHERMOPHILUS BY IMPROVEMENT OF INTERNAL HYDROGEN-BONDING

NARCIS (Netherlands)

EIJSINK, VGH; VRIEND, G; VANDERZEE, [No Value; VANDENBURG, B; VENEMA, G

1992-01-01

In an attempt to increase the thermostability of the neutral proteinase of Bacillus stearothermophilus the buried Ala-170 was replaced by serine. Molecular-dynamics simulations showed that Ser-170 stabilizes the enzyme by formation of an internal hydrogen bond. In addition, the hydroxy group of

On neutral plasma oscillations

International Nuclear Information System (INIS)

Shadwick, B.A.; Morrison, P.J.

1993-06-01

We examine the conditions for the existence of spectrally stable neutral modes in a Vlasov-Poisson plasma and show that for stable equilibria of systems that have unbounded spatial domain, the only possible neutral modes are those with phase velocities that correspond to stationary inflection points of the equilibrium distribution function. It is seen that these neutral modes can possess positive or negative free energy

On neutral plasma oscillations

International Nuclear Information System (INIS)

Shadwick, B.A.; Texas Univ., Austin; Morrison, P.J.; Texas Univ., Austin

1994-01-01

We examine the conditions for the existence of spectrally stable neutral modes in a Vlasov-Poisson plasma and show that for stable equilibria of systems that have unbounded spatial domain, the only possible neutral modes are those with phase velocities that correspond to stationary inflection points of the equilibrium distribution function. It is seen that these neutral modes can posses positive or negative free energy. (orig.)

Automated Facial Coding Software Outperforms People in Recognizing Neutral Faces as Neutral from Standardized Datasets

Directory of Open Access Journals (Sweden)

Peter eLewinski

2015-09-01

Full Text Available Little is known about people’s accuracy of recognizing neutral faces as neutral. In this paper, I demonstrate the importance of knowing how well people recognize neutral faces. I contrasted human recognition scores of 100 typical, neutral front-up facial images with scores of an arguably objective judge – automated facial coding (AFC software. I hypothesized that the software would outperform humans in recognizing neutral faces because of the inherently objective nature of computer algorithms. Results confirmed this hypothesis. I provided the first-ever evidence that computer software (90% was more accurate in recognizing neutral faces than people were (59%. I posited two theoretical mechanisms, i.e. smile-as-a-baseline and false recognition of emotion, as possible explanations for my findings.

First observations of partially neutralized and quasineutral plasmas in the Columbia Non-neutral Torus

Science.gov (United States)

Sarasola, Xabier; Brenner, Paul; Hahn, Michael; Pedersen, Thomas

2009-11-01

The Columbia Non-neutral Torus (CNT) is the first stellarator devoted to the study of pure electron, partially neutralized and positron-electron plasmas. To date, CNT usually operates with electron rich plasmas (with negligible ion density) [1], but a stellarator can also confine plasmas of arbitrary degree of neutralization. In CNT the accumulation of ions alters the equilibrium of electron plasmas and a global instability has been observed when the ion fraction exceeds 10 %. A characterization of this instability is presented in [2], analyzing its parameter dependence and spatial structure (non- resonant with rational surfaces). A new set of experiments is currently underway studying plasmas of arbitrary degree of neutralization, ranging from pure electron to quasineutral plasmas. Basic observations show that the plasma potential decouples from emitter bias when we increase the degree of the neutralization of our plasmas. Partially neutralized plasmas are also characterized by multiple mode behavior with dominant modes between 20 and 200 kHz. When the plasma becomes quasineutral, it reverts to single mode behavior. The first results on partially neutralized plasmas confined on magnetic surfaces will be presented. [1] J. Kremer, PRL 97, (2006) 095003 [2] Q. Marksteiner, PRL 100 (2008) 065002

Plasma/Neutral-Beam Etching Apparatus

Science.gov (United States)

Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

1989-01-01

Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

Neutral theory and the species abundance distribution: recent developments and prospects for unifying niche and neutral perspectives

Science.gov (United States)

Matthews, Thomas J; Whittaker, Robert J

2014-01-01

Published in 2001, The Unified Neutral Theory of Biodiversity and Biogeography (UNTB) emphasizes the importance of stochastic processes in ecological community structure, and has challenged the traditional niche-based view of ecology. While neutral models have since been applied to a broad range of ecological and macroecological phenomena, the majority of research relating to neutral theory has focused exclusively on the species abundance distribution (SAD). Here, we synthesize the large body of work on neutral theory in the context of the species abundance distribution, with a particular focus on integrating ideas from neutral theory with traditional niche theory. First, we summarize the basic tenets of neutral theory; both in general and in the context of SADs. Second, we explore the issues associated with neutral theory and the SAD, such as complications with fitting and model comparison, the underlying assumptions of neutral models, and the difficultly of linking pattern to process. Third, we highlight the advances in understanding of SADs that have resulted from neutral theory and models. Finally, we focus consideration on recent developments aimed at unifying neutral- and niche-based approaches to ecology, with a particular emphasis on what this means for SAD theory, embracing, for instance, ideas of emergent neutrality and stochastic niche theory. We put forward the argument that the prospect of the unification of niche and neutral perspectives represents one of the most promising future avenues of neutral theory research. PMID:25360266

Neutral theory and the species abundance distribution: recent developments and prospects for unifying niche and neutral perspectives.

Science.gov (United States)

Matthews, Thomas J; Whittaker, Robert J

2014-06-01

Published in 2001, The Unified Neutral Theory of Biodiversity and Biogeography (UNTB) emphasizes the importance of stochastic processes in ecological community structure, and has challenged the traditional niche-based view of ecology. While neutral models have since been applied to a broad range of ecological and macroecological phenomena, the majority of research relating to neutral theory has focused exclusively on the species abundance distribution (SAD). Here, we synthesize the large body of work on neutral theory in the context of the species abundance distribution, with a particular focus on integrating ideas from neutral theory with traditional niche theory. First, we summarize the basic tenets of neutral theory; both in general and in the context of SADs. Second, we explore the issues associated with neutral theory and the SAD, such as complications with fitting and model comparison, the underlying assumptions of neutral models, and the difficultly of linking pattern to process. Third, we highlight the advances in understanding of SADs that have resulted from neutral theory and models. Finally, we focus consideration on recent developments aimed at unifying neutral- and niche-based approaches to ecology, with a particular emphasis on what this means for SAD theory, embracing, for instance, ideas of emergent neutrality and stochastic niche theory. We put forward the argument that the prospect of the unification of niche and neutral perspectives represents one of the most promising future avenues of neutral theory research.

On plasma-neutral gas interaction

International Nuclear Information System (INIS)

Venkataramani, N.; Mattoo, S.K.

1980-01-01

The importance of plasma-neutral gas interaction layer has been emphasized by pointing out its application to a wide variety of physical phenomena. The interaction of a magnetised plasma stream penetrating a neutral gas cloud is discussed in the light of Alfven's critical velocity and Varma's threshold velocity on the ionising interaction. Interaction of a moving magnetised plasma with a stationary neutral gas has been studied and described. The device comprises of a plasma gun and an interaction region where neutral gas cloud is injected. The interaction region is provided with a transverse magnetic field of upto 1000 G. Several diagnostics deployed at the interaction region to make measurements on the macroscopic parameters of plasma and neutral gas are described. The parameters of discharge circuits are measured with high current and voltage probes. An interaction between a magnetised plasma stream and a neutral gas cloud is demonstrated. It is shown that this interaction does not have Varma's threshold on their relative velocity. The Alfven's critical velocity phenomenon is shown to depend on the integrated column neutral gas density that a plasma stream encounters while penetrating through it and not on the neutral gas density in the range of 10 17 -10 21 m -3 . (auth.)

Subcellular localization of human neutral ceramidase expressed in HEK293 cells

International Nuclear Information System (INIS)

Hwang, Young-ha; Tani, Motohiro; Nakagawa, Tetsuto; Okino, Nozomu; Ito, Makoto

2005-01-01

We previously reported that rat and mouse neutral ceramidases were mainly localized to plasma membranes as a type II integral membrane protein and partly detached from the cells via processing of the N-terminal/anchor sequence when expressed in HEK293 cells [M. Tani, H. Iida, M. Ito, O-glycosylation of mucin-like domain retains the neutral ceramidase on the plasma membranes as a type II integral membrane protein, J. Biol. Chem. 278 (2003) 10523-10530]. In contrast, the human homologue was exclusively detected in mitochondria when expressed in HEK293 and MCF7 cells as a fusion protein with green fluorescent protein at the N-terminal of the enzyme [S.E. Bawab, P. Roddy, T. Quian, A. Bielawska, J.J. Lemasters, Y.A. Hannun, Molecular cloning and characterization of a human mitochondrial ceramidase, J. Biol. Chem. 275 (2000) 21508-21513]. Given this discrepancy, we decided to clone the neutral ceramidase from human kidney cDNA and re-examine the intracellular localization of the enzyme when expressed in HEK293 cells. The putative amino acid sequence of the newly cloned enzyme was identical to that reported for human neutral ceramidase except at the N-terminal; the new protein was 19 amino acids longer at the N-terminal. We found that the putative full-length human neutral ceramidase was transported to plasma membranes, but not to mitochondria, possibly via a classical ER/Golgi pathway and localized mainly in plasma membranes when expressed in HEK293 cells. The N-terminal-truncated mutant, previously reported as a human mitochondrial ceramidase, was also weakly expressed in HEK293 cells but mainly released into the medium possibly due to the insufficient signal/anchor sequence

Neutralization of methyl cation via chemical reactions in low-energy ion-surface collisions with fluorocarbon and hydrocarbon self-assembled monolayer films.

Science.gov (United States)

Somogyi, Arpád; Smith, Darrin L; Wysocki, Vicki H; Colorado, Ramon; Lee, T Randall

2002-10-01

Low-energy ion-surface collisions of methyl cation at hydrocarbon and fluorocarbon self-assembled monolayer (SAM) surfaces produce extensive neutralization of CH3+. These experimental observations are reported together with the results obtained for ion-surface collisions with the molecular ions of benzene, styrene, 3-fluorobenzonitrile, 1,3,5-triazine, and ammonia on the same surfaces. For comparison, low-energy gas-phase collisions of CD3+ and 3-fluorobenzonitrile molecular ions with neutral n-butane reagent gas were conducted in a triple quadrupole (QQQ) instrument. Relevant MP2 6-31G*//MP2 6-31G* ab initio and thermochemical calculations provide further insight in the neutralization mechanisms of methyl cation. The data suggest that neutralization of methyl cation with hydrocarbon and fluorocarbon SAMs occurs by concerted chemical reactions, i.e., that neutralization of the projectile occurs not only by a direct electron transfer from the surface but also by formation of a neutral molecule. The calculations indicate that the following products can be formed by exothermic processes and without appreciable activation energy: CH4 (formal hydride ion addition) and C2H6 (formal methyl anion addition) from a hydrocarbon surface and CH3F (formal fluoride addition) from a fluorocarbon surface. The results also demonstrate that, in some cases, simple thermochemical calculations cannot be used to predict the energy profiles because relatively large activation energies can be associated with exothermic reactions, as was found for the formation of CH3CF3 (formal addition of trifluoromethyl anion).

Is an inequality-neutral flat tax reform really neutral?

OpenAIRE

Juan Prieto Rodríguez; Juan Gabriel Rodríguez; Rafael Salas

2004-01-01

. Let us assume a revenue- and inequality-neutral flat tax reform shifting from a graduated-rate tax. Is this reform really neutral in terms of the income distribution? Traditionally, there has been a bias toward the inequality analysis, forgetting other relevant aspects of the income distribution. This kind of reforms implies a set of composite transfers, both progressive and regressive, even though inequality remains unchanged. This paper shows that polarization is a useful tool for charact...

Deleterious alleles in the human genome are on average younger than neutral alleles of the same frequency

NARCIS (Netherlands)

Kiezun, Adam; Pulit, Sara L.; Francioli, Laurent C.; van Dijk, Freerk; Swertz, Morris; Boomsma, Dorret I.; van Duijn, Cornelia M.; Slagboom, P. Eline; van Ommen, G. J. B.; Wijmenga, Cisca; de Bakker, Paul I. W.; Sunyaev, Shamil R.

Large-scale population sequencing studies provide a complete picture of human genetic variation within the studied populations. A key challenge is to identify, among the myriad alleles, those variants that have an effect on molecular function, phenotypes, and reproductive fitness. Most non-neutral

Ionized and Neutral Outflows in the QUEST QSOs

Science.gov (United States)

Veilleux, Sylvain

2011-10-01

The role of galactic winds in gas-rich mergers is of crucial importance to understand galaxy and SMBH evolution. In recent months, our group has had three major scientific breakthroughs in this area: {1} The discovery with Herschel of massive molecular {OH-absorbing} outflows in several ULIRGs, including the nearest quasar, Mrk 231. {2} The independent discovery from mm-wave interferometric observations in the same object of a spatially resolved molecular {CO-emitting} wind with estimated mass outflow rate 3x larger than the star formation rate and spatially coincident with blueshifted neutral {Na ID-absorbing} gas in optical long-slit spectra. {3} The unambiguous determination from recent Gemini/IFU observations that the Na ID outflow in this object is wide-angle, thus driven by a QSO wind rather than a jet. This powerful outflow may be the long-sought "smoking gun" of quasar mechanical feedback purported to transform gas-rich mergers. However, our Herschel survey excludes all FIR-faint {UV-bright} "classic" QSOs by necessity. So here we propose a complementary FUV absorption-line survey of all FIR-bright -and- FIR-faint QSOs from the same parent sample. New {19 targets} and archival {11} spectra will be used to study, for the first time, the gaseous environments of QSOs as a function of host properties and age across the merger sequence ULIRG -> QSO. These data will allow us to distinguish between ionized & neutral quasar-driven outflows, starburst-driven winds, and tidal debris around the mergers. They will also be uniquely suited for a shallow but broad study of the warm & warm-hot intergalactic media, complementary to on-going surveys that are deeper but narrower.

Sensing the Worst: Neurophenomenological Perspectives on Neutral Stimuli Misperception in Schizophrenia Spectrum

Directory of Open Access Journals (Sweden)

Mariateresa Sestito

2017-06-01

Full Text Available While investigating social cognitive impairments in schizophrenia, prominent evidence has been found that patients with schizophrenia show a tendency to misclassify neutral stimuli as negatively valenced. Within this population, patients presenting delusions are more prone to this phenomenon. In a previous study, Schizophrenia spectrum (SzSp patients rated positive, negative and neutral stimuli that were multimodally presented, while assessed with a checklist exploring anomalous subjective experiences and evaluated for positive and negative symptomatology. In the present work, we aimed to further explore the relationship between neutral stimuli misperception, anomalous experiences and positive/negative symptoms in SzSp patients. To this end, we adopted a dimensional approach by reconstructing from available data: (1 four a priori scales representing essential dimensions of SzSp experiential pathology following Parnas et al. (2005; and (2 five clinically meaningful factors to describe illness severity derived by Toomey et al. (1997. Results showed that although overall patients correctly recognized the target emotions, those who misinterpreted neutral auditory cues as negatively valenced also presented higher scores in Perplexity (PY, Bizarre Delusions (BD and Disorganization (Di dimensions. Moreover, a positive association between BD and both PY and Self-Disorder (SD dimensions emerged, suggesting that psychotic symptoms may be directly linked to patients’ subjectivity. In an attempt to comprehensively capture the multilayered neutral stimuli misperception phenomenon in SzSp, we aimed at bridging phenomenology and neurobiology by connecting the levels of molecular neurochemistry (i.e., altered dopaminergic neurotransmission, system neuroscience (aberrant salience of perceptual details and psychopathology (the chain involving hyper-reflexivity, self-disorders and the emergence of delusions.

Electrochemical corrosion behaviour of lead-free Sn-8.5 Zn-X Ag-0.1 Al-0.5 Ga solder in 3.5% NaCl solution

International Nuclear Information System (INIS)

Mohanty, Udit Surya; Lin, K.-L.

2005-01-01

The electrochemical corrosion behaviour of Pb-free Sn-8.5 Zn-X Ag-0.1 Al-0.5 Ga solder in 3.5% NaCl solution was investigated by using potentiodynamic polarization methods, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) analysis. The results obtained from polarization studies showed that an increase in the Ag content from 0.1 to 1.5 wt% decreased the corrosion current density (I corr ) and shifted the corrosion potential (E corr ) towards more noble values. These changes were also reflected in the linear polarization resistance (LPR), corrosion rate, anodic Tafel slope (b A ) and the cathodic Tafel slope (b c ) values, respectively. Passivation behaviour was noted in the Sn-Zn-X Ag-Al-Ga solders with Ag content > 0.1 wt%. The oxides and hydroxides of zinc were responsible for the formation of passive film. Presence of Ag atoms in the oxide layer also improved the passivation behaviour of solders to a certain extent. X-ray photoelectron spectroscopy revealed that two different oxygen species were formed on the surface films, one was assigned to OH - in Zn(OH) 2 and the other to O 2 - in ZnO. XPS depth profile results revealed that the two species had different depth distribution in the films. SEM and EDX analyses confirmed SnCl 2 as the major corrosion product formed after the electrochemical experiments

Gas utilization in TFTR [Tokamak Fusion Test Reactor] neutral beam injectors

International Nuclear Information System (INIS)

Kamperschroer, J.H.; Gammel, G.M.; Kugel, H.W.; Grisham, L.R.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

1987-08-01

Measurements of gas utilization in a test TFTR neutral beam injector have been performed to study the feasibility of running tritium neutral beams with existing ion sources. Gas consumption is limited by the restriction of 50,000 curies of T 2 allowed on site. It was found that the gas efficiency of the present long-pulse ion sources is higher than it was with previous short-pulse sources. Gas efficiencies were studied over the range of 35 to 55%. At the high end of this range the neutral fraction of the beam fell below that predicted by room temperature molecular gas flow. This is consistent with observations made on the JET injectors, where it has been attributed to beam heating of the neutralizer gas and a concomitant increase in conductance. It was found that a working gas isotope exchange from H 2 to D 2 could be accomplished on the first beam shot after changing the gas supply, without any intermediate preconditioning. The mechanism believed responsible for this phenomenon is heating of the plasma generator walls by the arc and a resulting thermal desorption of all previously adsorbed and implanted gas. Finally, it was observed that an ion source conditioned to 120 kV operation could produce a beam pulse after a waiting period of fourteen hours by preceding the beam extraction with several hi-pot/filament warm-up pulses, without any gas consumption. 18 refs., 7 figs., 2 tabs

Neutral forces acting on intragenomic variability shape the Escherichia coli regulatory network topology.

Science.gov (United States)

Ruths, Troy; Nakhleh, Luay

2013-05-07

Cis-regulatory networks (CRNs) play a central role in cellular decision making. Like every other biological system, CRNs undergo evolution, which shapes their properties by a combination of adaptive and nonadaptive evolutionary forces. Teasing apart these forces is an important step toward functional analyses of the different components of CRNs, designing regulatory perturbation experiments, and constructing synthetic networks. Although tests of neutrality and selection based on molecular sequence data exist, no such tests are currently available based on CRNs. In this work, we present a unique genotype model of CRNs that is grounded in a genomic context and demonstrate its use in identifying portions of the CRN with properties explainable by neutral evolutionary forces at the system, subsystem, and operon levels. We leverage our model against experimentally derived data from Escherichia coli. The results of this analysis show statistically significant and substantial neutral trends in properties previously identified as adaptive in origin--degree distribution, clustering coefficient, and motifs--within the E. coli CRN. Our model captures the tightly coupled genome-interactome of an organism and enables analyses of how evolutionary events acting at the genome level, such as mutation, and at the population level, such as genetic drift, give rise to neutral patterns that we can quantify in CRNs.

Predicting HIV-1 transmission and antibody neutralization efficacy in vivo from stoichiometric parameters.

Directory of Open Access Journals (Sweden)

Oliver F Brandenberg

2017-05-01

Full Text Available The potential of broadly neutralizing antibodies targeting the HIV-1 envelope trimer to prevent HIV-1 transmission has opened new avenues for therapies and vaccines. However, their implementation remains challenging and would profit from a deepened mechanistic understanding of HIV-antibody interactions and the mucosal transmission process. In this study we experimentally determined stoichiometric parameters of the HIV-1 trimer-antibody interaction, confirming that binding of one antibody is sufficient for trimer neutralization. This defines numerical requirements for HIV-1 virion neutralization and thereby enables mathematical modelling of in vitro and in vivo antibody neutralization efficacy. The model we developed accurately predicts antibody efficacy in animal passive immunization studies and provides estimates for protective mucosal antibody concentrations. Furthermore, we derive estimates of the probability for a single virion to start host infection and the risks of male-to-female HIV-1 transmission per sexual intercourse. Our work thereby delivers comprehensive quantitative insights into both the molecular principles governing HIV-antibody interactions and the initial steps of mucosal HIV-1 transmission. These insights, alongside the underlying, adaptable modelling framework presented here, will be valuable for supporting in silico pre-trial planning and post-hoc evaluation of HIV-1 vaccination or antibody treatment trials.

Neutral Buoyancy Laboratory (NBL)

Data.gov (United States)

Federal Laboratory Consortium — The Neutral Buoyancy Laboratory (NBL) is an astronaut training facility and neutral buoyancy pool operated by NASA and located at the Sonny Carter Training Facility,...

Electrophoretic mobilities of neutral analytes and electroosmotic flow markers in aqueous solutions of Hofmeister salts

Czech Academy of Sciences Publication Activity Database

Křížek, T.; Kubíčková, A.; Hladílková, Jana; Coufal, P.; Heyda, J.; Jungwirth, Pavel

2014-01-01

Roč. 35, č. 5 (2014), s. 617-624 ISSN 0173-0835 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : EOF markers * ion-specific effects * ion-specific mobilization * molecular dynamics simulations * neutral analytes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.028, year: 2014

3D-Printed Beam Splitter for Polar Neutral Molecules

Science.gov (United States)

Gordon, Sean D. S.; Osterwalder, Andreas

2017-04-01

We describe a macroscopic beam splitter for polar neutral molecules. A complex electrode structure is required for the beam splitter which would be very difficult to produce with traditional manufacturing methods. Instead, we make use of a nascent manufacturing technique: 3D printing of a plastic piece, followed by electroplating. This fabrication method opens a plethora of avenues for research, since 3D printing imposes practically no limitations on possible shapes, and the plating produces chemically robust, conductive construction elements with an almost free choice of surface material. It has the added advantage of dramatically reduced production cost and time. Our beam splitter is an electrostatic hexapole guide that smoothly transforms into two bent quadrupoles. We demonstrate the correct functioning of this device by separating a supersonic molecular beam of ND3 into two correlated fractions. It is shown that this device can be used to implement experiments with differential detection wherein one of the fractions serves as a probe and the other as a reference. Reverse operation would allow the merging of two beams of polar neutral molecules.

Neutral wind and density perturbations in the thermosphere created by gravity waves observed by the TIDDBIT sounder

Science.gov (United States)

Vadas, Sharon L.; Crowley, Geoff

2017-06-01

In this paper, we study the 10 traveling ionospheric disturbances (TIDs) observed at zobs˜283 km by the TIDDBIT ionospheric sounder on 30 October 2007 at 0400-0700 UT near Wallops Island, USA. These TIDs propagated northwest/northward and were previously found to be secondary gravity waves (GWs) from tropical storm Noel. An instrumented sounding rocket simultaneously measured a large neutral wind peak uH' with a similar azimuth at z ˜ 325 km. Using the measured TID amplitudes and wave vectors from the TIDDBIT system, together with ion-neutral theory, GW dissipative polarization relations and ray tracing, we determine the GW neutral horizontal wind and density perturbations as a function of altitude from 220 to 380 km. We find that there is a serious discrepancy between the GW dissipative theory and the observations unless the molecular viscosity, μ, decreases with altitude in the middle to upper thermosphere. Assuming that μ∝ρ¯q, where ρ¯ is the density, we find using GW dissipative theory that the GWs could have been observed at zobs and that one or more of the GWs could have caused the uH' wind peak at z≃325 km if q ˜ 0.67 for z≥220 km. This implies that the kinematic viscosity, ν=μ/ρ¯, increases less rapidly with altitude for z≥220 km: ν∝1/ρ¯0.33. This dependence makes sense because as ρ¯→0, the distance between molecules goes to infinity, which implies no molecular collisions and therefore no molecular viscosity μ.

International network for comparison of HIV neutralization assays: the NeutNet report.

Science.gov (United States)

Fenyö, Eva Maria; Heath, Alan; Dispinseri, Stefania; Holmes, Harvey; Lusso, Paolo; Zolla-Pazner, Susan; Donners, Helen; Heyndrickx, Leo; Alcami, Jose; Bongertz, Vera; Jassoy, Christian; Malnati, Mauro; Montefiori, David; Moog, Christiane; Morris, Lynn; Osmanov, Saladin; Polonis, Victoria; Sattentau, Quentin; Schuitemaker, Hanneke; Sutthent, Ruengpung; Wrin, Terri; Scarlatti, Gabriella

2009-01-01

Neutralizing antibody assessments play a central role in human immunodeficiency virus type-1 (HIV-1) vaccine development but it is unclear which assay, or combination of assays, will provide reliable measures of correlates of protection. To address this, an international collaboration (NeutNet) involving 18 independent participants was organized to compare different assays. Each laboratory evaluated four neutralizing reagents (TriMab, 447-52D, 4E10, sCD4) at a given range of concentrations against a panel of 11 viruses representing a wide range of genetic subtypes and phenotypes. A total of 16 different assays were compared. The assays utilized either uncloned virus produced in peripheral blood mononuclear cells (PBMCs) (virus infectivity assays, VI assays), or their Env-pseudotyped (gp160) derivatives produced in 293T cells (PSV assays) from molecular clones or uncloned virus. Target cells included PBMC and genetically-engineered cell lines in either a single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs that included extracellular or intracellular p24 antigen detection, RNA quantification and luciferase and beta-galactosidase reporter gene expression. PSV assays were generally more sensitive than VI assays, but there were important differences according to the virus and inhibitor used. For example, for TriMab, the mean IC50 was always lower in PSV than in VI assays. However, with 4E10 or sCD4 some viruses were neutralized with a lower IC50 in VI assays than in the PSV assays. Inter-laboratory concordance was slightly better for PSV than for VI assays with some viruses, but for other viruses agreement between laboratories was limited and depended on both the virus and the neutralizing reagent. The NeutNet project demonstrated clear differences in assay sensitivity that were dependent on both the neutralizing reagent and the virus. No single assay was capable of detecting the entire spectrum of neutralizing

Neutral currents

International Nuclear Information System (INIS)

Aubert, B.

1994-11-01

The evidence for the existence of weak neutral current has been a very controverted topics in the early 1970's, as well as the muon did in the 1930's. The history is very rich considering the evolution of the experimental techniques in high energy particle physics. The history of the discovery and the study of weak neutral current is reviewed. Later the quest of the intermediate vector boson continues with the decision of the community to build a large proton antiproton collider. (K.A.). 14 refs., 1 fig

Effect of the molecular weight of a neutral polysaccharide on soy protein gelation.

Science.gov (United States)

Monteiro, Sónia R; Lopes-da-Silva, José A

2017-12-01

The effects of galactomannans with different molecular weights on the heat-induced gelation characteristics of soybean protein were investigated using dynamic small-strain rheometry, under conditions where the proteins carry a net negative charge (pH7). Microstructure of the resulting gels was investigated by confocal laser scanning microscopy. Phase-separated systems were obtained with different morphologies and degree of phase separation, depending on both biopolymer concentrations and polysaccharide molecular weight. In general, a gelling enhancing effect on soy proteins was verified, despite extensive phase-separation processes observed at the higher polysaccharide molecular weight. This effect was demonstrated by an increase of the gelation rate, a decrease in the temperature at the onset of gelation, and an increase of gel stiffness and elastic character, with the length of polysaccharide chains. Overall, the results obtained established that the judicious selection of the galactomannan molecular weight may be used to modify the structure and gelation properties of soy proteins, originating a diversity of rheological characteristics and microstructures that will impact on the design of novel food formulations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Semiclassical neutral atom as a reference system in density functional theory.

Science.gov (United States)

Constantin, Lucian A; Fabiano, E; Laricchia, S; Della Sala, F

2011-05-06

We use the asymptotic expansions of the semiclassical neutral atom as a reference system in density functional theory to construct accurate generalized gradient approximations (GGAs) for the exchange-correlation and kinetic energies without any empiricism. These asymptotic functionals are among the most accurate GGAs for molecular systems, perform well for solid state, and overcome current GGA state of the art in frozen density embedding calculations. Our results also provide evidence for the conjointness conjecture between exchange and kinetic energies of atomic systems.

Atomic and molecular processes in fusion plasmas

Energy Technology Data Exchange (ETDEWEB)

Janev, R.K. [International Atomic Energy Agency, Vienna (Austria)

1997-01-01

The role of atomic and molecular processes in achieving and maintaining the conditions for thermonuclear burn in a magnetically confined fusion plasma is described. Emphasis is given to the energy balance and power and particle exhaust issues. The most important atomic and molecular processes which affect the radiation losses and impurity transport in the core plasma, the neutral particle transport in the plasma edge and the radiative cooling of divertor plasmas are discussed in greater detail. (author)

Chimeric rhinoviruses displaying MPER epitopes elicit anti-HIV neutralizing responses.

Directory of Open Access Journals (Sweden)

Guohua Yi

Full Text Available The development of an effective AIDS vaccine has been a formidable task, but remains a critical necessity. The well conserved membrane-proximal external region (MPER of the HIV-1 gp41 glycoprotein is one of the crucial targets for AIDS vaccine development, as it has the necessary attribute of being able to elicit antibodies capable of neutralizing diverse isolates of HIV.Guided by X-ray crystallography, molecular modeling, combinatorial chemistry, and powerful selection techniques, we designed and produced six combinatorial libraries of chimeric human rhinoviruses (HRV displaying the MPER epitopes corresponding to mAbs 2F5, 4E10, and/or Z13e1, connected to an immunogenic surface loop of HRV via linkers of varying lengths and sequences. Not all libraries led to viable chimeric viruses with the desired sequences, but the combinatorial approach allowed us to examine large numbers of MPER-displaying chimeras. Among the chimeras were five that elicited antibodies capable of significantly neutralizing HIV-1 pseudoviruses from at least three subtypes, in one case leading to neutralization of 10 pseudoviruses from all six subtypes tested.Optimization of these chimeras or closely related chimeras could conceivably lead to useful components of an effective AIDS vaccine. While the MPER of HIV may not be immunodominant in natural infection by HIV-1, its presence in a vaccine cocktail could provide critical breadth of protection.

Fluorescein isothiocyanate: Molecular characterization by theoretical calculations

Energy Technology Data Exchange (ETDEWEB)

Casanovas, Jordi [Departament de Quimica, Escola Politecnica Superior, Universitat de Lleida, c/Jaume II No 69, Lleida E-25001 (Spain); Jacquemin, Denis [Laboratoire de Chimie Theorique Appliquee, Facultes Universitaires Notre-Dame de la Paix, rue de Bruxelles, 61, B-5000 Namur (Belgium)], E-mail: denis.jacquemin@fundp.ac.be; Perpete, Eric A. [Laboratoire de Chimie Theorique Appliquee, Facultes Universitaires Notre-Dame de la Paix, rue de Bruxelles, 61, B-5000 Namur (Belgium); Aleman, Carlos [Departament d' Enginyeria Quimica, E. T. S. d' Enginyeria Industrial de Barcelona, Universitat Politecnica de Catalunya, Diagonal 647, Barcelona E-08028 (Spain)], E-mail: carlos.aleman@upc.edu

2008-12-10

Quantum mechanical calculations have been used to investigate the conformation, molecular geometry, basicity and spectroscopic properties of fluorescein isothiocyanate in both the gas-phase and aqueous solution. Specifically, calculations have been performed considering the neutral, monoanionic and dianionic forms of this important fluorescent compound. Results reveal that for the neutral form multiple conformational states are possible, all them with significant contributions, and the stability of the different conformers is similar in the gas-phase and aqueous solution. Calculation of the excitation energies revealed that spectroscopic properties are very sensitive to the relaxation effect in solution. A good agreement has been reached obtained between the experimental and theoretical values derived from time-dependent density functional theory methods for the neutral form, whereas for charged species the calculations fail to accurately reproduce the measured trends.

Structural Basis for Escape of Human Astrovirus from Antibody Neutralization: Broad Implications for Rational Vaccine Design

Energy Technology Data Exchange (ETDEWEB)

Bogdanoff, Walter A.; Perez, Edmundo I.; López, Tomás; Arias, Carlos F.; DuBois, Rebecca M. (UNAM-Mexico); (UCSC)

2017-10-25

Human astroviruses are recognized as a leading cause of viral diarrhea worldwide in children, immunocompromised patients, and the elderly. There are currently no vaccines available to prevent astrovirus infection; however, antibodies developed by healthy individuals during previous infection correlate with protection from reinfection, suggesting that an effective vaccine could be developed. In this study, we investigated the molecular mechanism by which several strains of human astrovirus serotype 2 (HAstV-2) are resistant to the potent HAstV-2-neutralizing monoclonal antibody PL-2 (MAb PL-2). Sequencing of the HAstV-2 capsid genes reveals mutations in the PL-2 epitope within the capsid's spike domain. To understand the molecular basis for resistance from MAb PL-2 neutralization, we determined the 1.35-Å-resolution crystal structure of the capsid spike from one of these HAstV-2 strains. Our structure reveals a dramatic conformational change in a loop within the PL-2 epitope due to a serine-to-proline mutation, locking the loop in a conformation that sterically blocks binding and neutralization by MAb PL-2. We show that mutation to serine permits loop flexibility and recovers MAb PL-2 binding. Importantly, we find that HAstV-2 capsid spike containing a serine in this loop is immunogenic and elicits antibodies that neutralize all HAstV-2 strains. Taken together, our results have broad implications for rational selection of vaccine strains that do not contain prolines in antigenic loops, so as to elicit antibodies against diverse loop conformations.

IMPORTANCEHuman astroviruses (HAstVs) infect nearly every person in the world during childhood and cause diarrhea, vomiting, and fever. In this study, we investigated how several strains of HAstV are resistant to a virus-neutralizing monoclonal antibody. We determined the crystal structure of the capsid protein spike domain from one of these HAstV strains and found that

Phenomenology of neutral current interactions

International Nuclear Information System (INIS)

Sakurai, J.J.

1978-01-01

Neutral-current interactions are discussed within a rather general phenomenological framework without commitment to any particular theoretical model. Three points are kept in mind: what various experiments really measure; the performing of complete experiments to determine the neutral-current couplings; and the testing of models in an objective, emotionally uninvolved manner. The following topics are considered: neutrino-electron scattering, hadronic currents and models, neutrino-induced inclusive hadronic reactions, neutrino-induced exclusive hadronic reactions, and neutral-current phenomena without neutrinos. In conclusion, what has actually been learned about neutral-current interactions is summarized. 9 figures, 2 tables

Structural basis for the binding of the neutralizing antibody, 7D11, to the poxvirus L1 protein

International Nuclear Information System (INIS)

Su, Hua-Poo; Golden, Joseph W.; Gittis, Apostolos G.; Hooper, Jay W.; Garboczi, David N.

2007-01-01

Medical countermeasures to prevent or treat smallpox are needed due to the potential use of poxviruses as biological weapons. Safety concerns with the currently available smallpox vaccine indicate a need for research on alternative poxvirus vaccine strategies. Molecular vaccines involving the use of proteins and/or genes and recombinant antibodies are among the strategies under current investigation. The poxvirus L1 protein, encoded by the L1R open reading frame, is the target of neutralizing antibodies and has been successfully used as a component of both protein subunit and DNA vaccines. L1-specific monoclonal antibodies (e.g., mouse monoclonal antibody mAb-7D11, mAb-10F5) with potent neutralizing activity bind L1 in a conformation-specific manner. This suggests that proper folding of the L1 protein used in molecular vaccines will affect the production of neutralizing antibodies and protection. Here, we co-crystallized the Fab fragment of mAb-7D11 with the L1 protein. The crystal structure of the complex between Fab-7D11 and L1 reveals the basis for the conformation-specific binding as recognition of a discontinuous epitope containing two loops that are held together by a disulfide bond. The structure of this important conformational epitope of L1 will contribute to the development of molecular poxvirus vaccines and also provides a novel target for anti-poxvirus drugs. In addition, the sequence and structure of Fab-7D11 will contribute to the development of L1-targeted immunotherapeutics

Divergence times in Caenorhabditis and Drosophila inferred from direct estimates of the neutral mutation rate.

Science.gov (United States)

Cutter, Asher D

2008-04-01

Accurate inference of the dates of common ancestry among species forms a central problem in understanding the evolutionary history of organisms. Molecular estimates of divergence time rely on the molecular evolutionary prediction that neutral mutations and substitutions occur at the same constant rate in genomes of related species. This underlies the notion of a molecular clock. Most implementations of this idea depend on paleontological calibration to infer dates of common ancestry, but taxa with poor fossil records must rely on external, potentially inappropriate, calibration with distantly related species. The classic biological models Caenorhabditis and Drosophila are examples of such problem taxa. Here, I illustrate internal calibration in these groups with direct estimates of the mutation rate from contemporary populations that are corrected for interfering effects of selection on the assumption of neutrality of substitutions. Divergence times are inferred among 6 species each of Caenorhabditis and Drosophila, based on thousands of orthologous groups of genes. I propose that the 2 closest known species of Caenorhabditis shared a common ancestor <24 MYA (Caenorhabditis briggsae and Caenorhabditis sp. 5) and that Caenorhabditis elegans diverged from its closest known relatives <30 MYA, assuming that these species pass through at least 6 generations per year; these estimates are much more recent than reported previously with molecular clock calibrations from non-nematode phyla. Dates inferred for the common ancestor of Drosophila melanogaster and Drosophila simulans are roughly concordant with previous studies. These revised dates have important implications for rates of genome evolution and the origin of self-fertilization in Caenorhabditis.

Neutral Polymeric Micelles for RNA Delivery

Science.gov (United States)

Lundy, Brittany B.; Convertine, Anthony; Miteva, Martina; Stayton, Patrick S.

2013-01-01

RNA interference (RNAi) drugs have significant therapeutic potential but delivery systems with appropriate efficacy and toxicity profiles are still needed. Here, we describe a neutral, ampholytic polymeric delivery system based on conjugatable diblock polymer micelles. The diblock copolymer contains a hydrophilic poly[N-(2-hydroxypropyl) methacrylamide-co-N-(2-(pyridin-2- yldisulfanyl)ethyl)methacrylamide) (poly[HPMA-co-PDSMA]) segment to promote aqueous stability and facilitate thiol-disulfide exchange reactions, and a second ampholytic block composed of propyl acrylic acid (PAA), dimethylaminoethyl methacrylate (DMAEMA), and butyl methacrylate (BMA). The poly[(HPMA-co-PDSMA)-b-(PAA-co-DMAEMA-co-BMA)] was synthesized using Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization with an overall molecular weight of 22,000 g/mol and a PDI of 1.88. Dynamic light scattering and fluorescence measurements indicated that the diblock copolymers self-assemble under aqueous conditions to form polymeric micelles with a hydrodynamic radius and critical micelle concentration of 25 nm and 25 μg/mL respectively. Red blood cell hemolysis experiments show that the neutral hydrophilic micelles have potent membrane destabilizing activity at endosomal pH values. Thiolated siRNA targeting glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was directly conjugated to the polymeric micelles via thiol exchange reactions with the pyridal disulfide groups present in the micelle corona. Maximum silencing activity in HeLa cells was observed at a 1:10 molar ratio of siRNA to polymer following a 48 h incubation period. Under these conditions 90 % mRNA knockdown and 65 % and protein knockdown of at 48 h was achieved with negligible toxicity. In contrast the polymeric micelles lacking a pH-responsive endosomalytic segment demonstrated negligible mRNA and protein knockdown under these conditions. The potent mRNA knockdown and excellent biocompatibility of the neutral siRNA conjugates

Method for the elucidation of the elemental composition of low molecular mass chemicals using exact masses of product ions and neutral losses: application to environmental chemicals measured by liquid chromatography with hybrid quadrupole/time-of-flight mass spectrometry.

Science.gov (United States)

Suzuki, Shigeru; Ishii, Tetsuko; Yasuhara, Akio; Sakai, Shinichi

2005-01-01

A method for elucidating the elemental compositions of low molecular weight chemicals, based primarily on mass measurements made using liquid chromatography (LC) with time-of-flight mass spectrometry (TOFMS) and quadrupole/time-of-flight mass spectrometry (LC/QTOFMS), was developed and tested for 113 chemicals of environmental interest with molecular masses up to approximately 400 Da. As the algorithm incorporating the method is not affected by differences in the instrument used, or by the ionization method and other ionization conditions, the method is useful not only for LC/TOFMS, but also for all kinds of mass spectra measured with higher accuracy and precision (uncertainties of a few mDa) employing all ionization methods and on-line separation techniques. The method involves calculating candidate compositions for intact ionized molecules (ionized forms of the sample molecule that have lost or gained no more than a proton, i.e., [M+H](+) or [M-H](-)) as well as for fragment ions and corresponding neutral losses, and eliminating those atomic compositions for the molecules that are inconsistent with the corresponding candidate compositions of fragment ions and neutral losses. Candidate compositions were calculated for the measured masses of the intact ionized molecules and of the fragment ions and corresponding neutral losses, using mass uncertainties of 2 and 5 mDa, respectively. Compositions proposed for the ionized molecule that did not correspond to the sum of the compositions of a candidate fragment ion and its corresponding neutral loss were discarded. One, 2-5, 6-10, 11-20, and >20 candidate compositions were found for 65%, 39%, 1%, 1%, and 0%, respectively, for the 124 ionized molecules formed from the 113 chemicals tested (both positive and negative ions were obtained from 11 of the chemicals). However, no candidate composition was found for 2% of the test cases (i.e., 3 chemicals), for each of which the measured mass of one of the product ions was in

Structural basis for the antibody neutralization of Herpes simplex virus

Energy Technology Data Exchange (ETDEWEB)

Lee, Cheng-Chung; Lin, Li-Ling [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Chan, Woan-Eng [Development Center for Biotechnology, New Taipei City 221, Taiwan (China); Ko, Tzu-Ping [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Lai, Jiann-Shiun [Development Center for Biotechnology, New Taipei City 221, Taiwan (China); Ministry of Economic Affairs, Taipei 100, Taiwan (China); Wang, Andrew H.-J., E-mail: ahjwang@gate.sinica.edu.tw [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Taipei Medical University, Taipei 110, Taiwan (China)

2013-10-01

The gD–E317-Fab complex crystal revealed the conformational epitope of human mAb E317 on HSV gD, providing a molecular basis for understanding the viral neutralization mechanism. Glycoprotein D (gD) of Herpes simplex virus (HSV) binds to a host cell surface receptor, which is required to trigger membrane fusion for virion entry into the host cell. gD has become a validated anti-HSV target for therapeutic antibody development. The highly inhibitory human monoclonal antibody E317 (mAb E317) was previously raised against HSV gD for viral neutralization. To understand the structural basis of antibody neutralization, crystals of the gD ectodomain bound to the E317 Fab domain were obtained. The structure of the complex reveals that E317 interacts with gD mainly through the heavy chain, which covers a large area for epitope recognition on gD, with a flexible N-terminal and C-terminal conformation. The epitope core structure maps to the external surface of gD, corresponding to the binding sites of two receptors, herpesvirus entry mediator (HVEM) and nectin-1, which mediate HSV infection. E317 directly recognizes the gD–nectin-1 interface and occludes the HVEM contact site of gD to block its binding to either receptor. The binding of E317 to gD also prohibits the formation of the N-terminal hairpin of gD for HVEM recognition. The major E317-binding site on gD overlaps with either the nectin-1-binding residues or the neutralizing antigenic sites identified thus far (Tyr38, Asp215, Arg222 and Phe223). The epitopes of gD for E317 binding are highly conserved between two types of human herpesvirus (HSV-1 and HSV-2). This study enables the virus-neutralizing epitopes to be correlated with the receptor-binding regions. The results further strengthen the previously demonstrated therapeutic and diagnostic potential of the E317 antibody.

Generation time, life history and the substitution rate of neutral mutations.

Science.gov (United States)

Lehtonen, Jussi; Lanfear, Robert

2014-11-01

Our understanding of molecular evolution is hampered by a lack of quantitative predictions about how life-history (LH) traits should correlate with substitution rates. Comparative studies have shown that neutral substitution rates vary substantially between species, and evidence shows that much of this diversity is associated with variation in LH traits. However, while these studies often agree, some unexplained and contradictory results have emerged. Explaining these results is difficult without a clear theoretical understanding of the problem. In this study, we derive predictions for the relationships between LH traits and substitution rates in iteroparous species by using demographic theory to relate commonly measured life-history traits to genetic generation time, and by implication to neutral substitution rates. This provides some surprisingly simple explanations for otherwise confusing patterns, such as the association between fecundity and substitution rates. The same framework can be applied to more complex life histories if full life-tables are available. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Is a neutral expression also a neutral stimulus? A study with functional magnetic resonance.

Science.gov (United States)

Carvajal, Fernando; Rubio, Sandra; Serrano, Juan M; Ríos-Lago, Marcos; Alvarez-Linera, Juan; Pacheco, Lara; Martín, Pilar

2013-08-01

Although neutral faces do not initially convey an explicit emotional message, it has been found that individuals tend to assign them an affective content. Moreover, previous research has shown that affective judgments are mediated by the task they have to perform. Using functional magnetic resonance imaging in 21 healthy participants, we focus this study on the cerebral activity patterns triggered by neutral and emotional faces in two different tasks (social or gender judgments). Results obtained, using conjunction analyses, indicated that viewing both emotional and neutral faces evokes activity in several similar brain areas indicating a common neural substrate. Moreover, neutral faces specifically elicit activation of cerebellum, frontal and temporal areas, while emotional faces involve the cuneus, anterior cingulated gyrus, medial orbitofrontal cortex, posterior superior temporal gyrus, precentral/postcentral gyrus and insula. The task selected was also found to influence brain activity, in that the social task recruited frontal areas while the gender task involved the posterior cingulated, inferior parietal lobule and middle temporal gyrus to a greater extent. Specifically, in the social task viewing neutral faces was associated with longer reaction times and increased activity of left dorsolateral frontal cortex compared with viewing facial expressions of emotions. In contrast, in the same task emotional expressions distinctively activated the left amygdale. The results are discussed taking into consideration the fact that, like other facial expressions, neutral expressions are usually assigned some emotional significance. However, neutral faces evoke a greater activation of circuits probably involved in more elaborate cognitive processing.

Molecular Population Genetics.

Science.gov (United States)

Casillas, Sònia; Barbadilla, Antonio

2017-03-01

Molecular population genetics aims to explain genetic variation and molecular evolution from population genetics principles. The field was born 50 years ago with the first measures of genetic variation in allozyme loci, continued with the nucleotide sequencing era, and is currently in the era of population genomics. During this period, molecular population genetics has been revolutionized by progress in data acquisition and theoretical developments. The conceptual elegance of the neutral theory of molecular evolution or the footprint carved by natural selection on the patterns of genetic variation are two examples of the vast number of inspiring findings of population genetics research. Since the inception of the field, Drosophila has been the prominent model species: molecular variation in populations was first described in Drosophila and most of the population genetics hypotheses were tested in Drosophila species. In this review, we describe the main concepts, methods, and landmarks of molecular population genetics, using the Drosophila model as a reference. We describe the different genetic data sets made available by advances in molecular technologies, and the theoretical developments fostered by these data. Finally, we review the results and new insights provided by the population genomics approach, and conclude by enumerating challenges and new lines of inquiry posed by increasingly large population scale sequence data. Copyright © 2017 Casillas and Barbadilla.

An overview of atomic and molecular processes in critical velocity ionization

International Nuclear Information System (INIS)

Lai, S.T.; Murad, E.; McNeil, W.J.

1989-01-01

Alfven's critical ionization velocity (CIV) is a multistep process involving plasma physics and plasma chemistry. The authors present an overview of the time development of some atomic and molecular processes in CIV. In the pre-onset stage, metastable states play an important role: They provide an energy pooling mechanism allowing low energy electrons to participate in the ionization processes; they may explain the low energy threshold as well as the fast time scale in the onset of CIV. For a sustaining CIV to occur, Townsend's criterion has to be satisfied. The kinetic energies of the neutrals are transformed to plasma wave energies via beam-plasma instabilities, and the plasma waves that heat the electrons result in a tail formation. Excitation of neutrals with subsequent radiation is an important energy loss mechanism. Finite beam size also limits the instability growth rate. In the propagation of CIV, ion-molecule reactions and molecular dissociative recombination are important. Ion-molecule reactions change the temporal chemical composition in a CIV process and help explain some results in CIV experiments. Molecular dissociative recombination reduces the plasma density, lowers the effective neutral mass, and loses energy via excitation and radiation; it tends to quench the propagation of CIV. Depending on various parameters, oscillatory behavior of CIV may occur

ORNL positive ion neutral beam program

International Nuclear Information System (INIS)

Whealton, J.H.; Haselton, H.H.; Barber, G.C.

1978-01-01

The neutral beam group at Oak Ridge National Laboratory has constructed neutral beam generators for the ORMAK and PLT devices, is presently constructing neutral beam devices for the ISX and PDX devices, and is contemplating the construction of neutral beam systems for the advanced TNS device. These neutral beam devices stem from the pioneering work on ion sources of G. G. Kelley and O. B. Morgan. We describe the ion sources under development at this Laboratory, the beam optics exhibited by these sources, as well as some theoretical considerations, and finally the remainder of the beamline design

Genetic signatures in the envelope glycoproteins of HIV-1 that associate with broadly neutralizing antibodies.

Directory of Open Access Journals (Sweden)

S Gnanakaran

Full Text Available A steady increase in knowledge of the molecular and antigenic structure of the gp120 and gp41 HIV-1 envelope glycoproteins (Env is yielding important new insights for vaccine design, but it has been difficult to translate this information to an immunogen that elicits broadly neutralizing antibodies. To help bridge this gap, we used phylogenetically corrected statistical methods to identify amino acid signature patterns in Envs derived from people who have made potently neutralizing antibodies, with the hypothesis that these Envs may share common features that would be useful for incorporation in a vaccine immunogen. Before attempting this, essentially as a control, we explored the utility of our computational methods for defining signatures of complex neutralization phenotypes by analyzing Env sequences from 251 clonal viruses that were differentially sensitive to neutralization by the well-characterized gp120-specific monoclonal antibody, b12. We identified ten b12-neutralization signatures, including seven either in the b12-binding surface of gp120 or in the V2 region of gp120 that have been previously shown to impact b12 sensitivity. A simple algorithm based on the b12 signature pattern was predictive of b12 sensitivity/resistance in an additional blinded panel of 57 viruses. Upon obtaining these reassuring outcomes, we went on to apply these same computational methods to define signature patterns in Env from HIV-1 infected individuals who had potent, broadly neutralizing responses. We analyzed a checkerboard-style neutralization dataset with sera from 69 HIV-1-infected individuals tested against a panel of 25 different Envs. Distinct clusters of sera with high and low neutralization potencies were identified. Six signature positions in Env sequences obtained from the 69 samples were found to be strongly associated with either the high or low potency responses. Five sites were in the CD4-induced coreceptor binding site of gp120, suggesting an

Gas cell neutralizers (Fundamental principles)

International Nuclear Information System (INIS)

Fuehrer, B.

1985-06-01

Neutralizing an ion-beam of the size and energy levels involved in the neutral-particle-beam program represents a considerable extension of the state-of-the-art of neutralizer technology. Many different mediums (e.g., solid, liquid, gas, plasma, photons) can be used to strip the hydrogen ion of its extra electron. A large, multidisciplinary R and D effort will no doubt be required to sort out all of the ''pros and cons'' of these various techniques. The purpose of this particular presentation is to discuss some basic configurations and fundamental principles of the gas type of neutralizer cell. Particular emphasis is placed on the ''Gasdynamic Free-Jet'' neutralizer since this configuration has the potential of being much shorter than other type of gas cells (in the beam direction) and it could operate in nearly a continuous mode (CW) if necessary. These were important considerations in the ATSU design which is discussed in some detail in the second presentation entitled ''ATSU Point Design''

Fluorescent and Colorimetric Molecular Recognition Probe for Hydrogen Bond Acceptors

OpenAIRE

Pike, Sarah Jane; Hunter, Christopher Alexander

2018-01-01

The association constants for formation of 1 : 1 complexes between a H-bond donor, 1-naphthol, and a diverse range of charged and neutral H-bond acceptors have been measured using UV/vis absorption and fluorescence emission titrations. The performance of 1-naphthol as a dual colorimetric and fluorescent molecular recognition probe for determining the H-bond acceptor (HBA) parameters of charged and neutral solutes has been investigated in three solvents. The data were employed to establish sel...

New Modulation Strategy to Balance the Neutral-Point Voltage for Three-Level Neutral-Clamped Inverter Systems

DEFF Research Database (Denmark)

Choi, Uimin; Lee, June-Seok; Lee, Kyo-Beum

2014-01-01

This paper proposes a new modulation strategy that balances the neutral-point voltage for three-level neutral-clamped inverter systems. The proposed modulation replaces the P-type or N-type small switching states with other switching states that do not affect the neutral-point voltage. The zero...... and medium switching states are employed to help the neutral-point voltage balancing. This method little bit increases the switching events and output total harmonic distortion. However, this method has a strong balancing ability at all regions. Further, it is very simple to implement in both space vector...

Electrostatic self-assembly in polyelectrolyte-neutral block copolymers and oppositely charged surfactant solutions

International Nuclear Information System (INIS)

Berret, J.-F.Jean-Francois; Oberdisse, Julian

2004-01-01

We report on small-angle neutron scattering (SANS) of colloidal complexes resulting from the electrostatic self-assembly of polyelectrolyte-neutral copolymers and oppositely charged surfactants. The polymers are double hydrophilic block copolymers of low molecular weight (between 5000 and 50 000 g/mol). One block is a polyelectrolyte chain, which can be either positively or negatively charged, whereas the second block is neutral and in good solvent conditions. In aqueous solutions, surfactants with an opposite charge to that of the polyelectrolyte interact strongly with these copolymers. The two species associate into stable 100 nm-colloidal complexes which exhibit a core-shell microstructure. For different polymer/surfactant couples, we have shown that the core is constituted from densely packed surfactant micelles connected by the polyelectrolyte chains. The outer part of the complex is a corona formed by the neutral soluble chains. Using a model of aggregation based on a Monte-Carlo algorithm, we have simulated the internal structure of the aggregates. The model assumes spherical cages containing one to several hundreds of micelles in a closely packed state. The agreement between the model and the data is remarkable

International network for comparison of HIV neutralization assays: the NeutNet report.

Directory of Open Access Journals (Sweden)

Eva Maria Fenyö

Full Text Available Neutralizing antibody assessments play a central role in human immunodeficiency virus type-1 (HIV-1 vaccine development but it is unclear which assay, or combination of assays, will provide reliable measures of correlates of protection. To address this, an international collaboration (NeutNet involving 18 independent participants was organized to compare different assays.Each laboratory evaluated four neutralizing reagents (TriMab, 447-52D, 4E10, sCD4 at a given range of concentrations against a panel of 11 viruses representing a wide range of genetic subtypes and phenotypes. A total of 16 different assays were compared. The assays utilized either uncloned virus produced in peripheral blood mononuclear cells (PBMCs (virus infectivity assays, VI assays, or their Env-pseudotyped (gp160 derivatives produced in 293T cells (PSV assays from molecular clones or uncloned virus. Target cells included PBMC and genetically-engineered cell lines in either a single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs that included extracellular or intracellular p24 antigen detection, RNA quantification and luciferase and beta-galactosidase reporter gene expression.PSV assays were generally more sensitive than VI assays, but there were important differences according to the virus and inhibitor used. For example, for TriMab, the mean IC50 was always lower in PSV than in VI assays. However, with 4E10 or sCD4 some viruses were neutralized with a lower IC50 in VI assays than in the PSV assays. Inter-laboratory concordance was slightly better for PSV than for VI assays with some viruses, but for other viruses agreement between laboratories was limited and depended on both the virus and the neutralizing reagent.The NeutNet project demonstrated clear differences in assay sensitivity that were dependent on both the neutralizing reagent and the virus. No single assay was capable of detecting the entire spectrum of

How Objective a Neutral Word Is? A Neutrosophic Approach for the Objectivity Degrees of Neutral Words

Directory of Open Access Journals (Sweden)

Mihaela Colhon

2017-11-01

Full Text Available In the latest studies concerning the sentiment polarity of words, the authors mostly consider the positive and negative constructions, without paying too much attention to the neutral words, which can have, in fact, significant sentiment degrees. More precisely, not all the neutral words have zero positivity or negativity scores, some of them having quite important nonzero scores for these polarities. At this moment, in the literature, a word is considered neutral if its positive and negative scores are equal, which implies two possibilities: (1 zero positive and negative scores; (2 nonzero, but equal positive and negative scores. It is obvious that these cases represent two different categories of neutral words that must be treated separately by a sentiment analysis task. In this paper, we present a comprehensive study about the neutral words applied to English as is developed with the aid of SentiWordNet 3.0: the publicly available lexical resource for opinion mining. We designed our study in order to provide an accurate classification of the so-called “neutral words” described in terms of sentiment scores and using measures from neutrosophy theory. The intended scope is to fill the gap concerning the neutrality aspect by giving precise measurements for the words’ objectivity.

Neutral-beam-heating applications and development

International Nuclear Information System (INIS)

Menon, M.M.

1981-01-01

The technique of heating the plasma in magnetically confined fusion devices by the injection of intense beams of neutral atoms is described. The basic principles governing the physics of neutral beam heating and considerations involved in determining the injection energy, power, and pulse length required for a fusion reactor are discussed. The pertinent experimental results from various fusion devices are surveyed to illustrate the efficacy of this technique. The second part of the paper is devoted to the technology of producing the neutral beams. A state-of-the-art account o the development of neutral injectors is presented, and the prospects for utilizing neutral injection to heat the plasma in a fusion reactor are examined

Interplay of electronic and geometry shell effects in properties of neutral and charged Sr clusters

DEFF Research Database (Denmark)

Lyalin, Andrey; Solov'yov, Ilia; Solov'yov, Andrey V.

2007-01-01

that the size evolution of structural and electronic properties of strontium clusters is governed by an interplay of the electronic and geometry shell closures. Influence of the electronic shell effects on structural rearrangements can lead to violation of the icosahedral growth motif of strontium clusters......The optimized structure and electronic properties of neutral, singly, and doubly charged strontium clusters have been investigated using ab initio theoretical methods based on density-functional theory. We have systematically calculated the optimized geometries of neutral, singly, and doubly...... charged strontium clusters consisting of up to 14 atoms, average bonding distances, electronic shell closures, binding energies per atom, the gap between the highest occupied and the lowest unoccupied molecular orbitals, and spectra of the density of electronic states (DOS). It is demonstrated...

Neutral-point current modeling and control for Neutral-Point Clamped three-level converter drive with small DC-link capacitors

DEFF Research Database (Denmark)

Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, Sergio

2011-01-01

A Neutral-Point-Clamped (NPC) three-level inverter with small DC-link capacitors is presented in this paper. This inverter requires zero average neutral-point current for stable neutral-point potential. A simple carrier based modulation strategy is proposed for achieving zero average neutral...... drive with only 14 μF DC-link capacitors. A fast and stable performance of the neutral-point voltage controller is achieved and verified by experiments....

Adsorption and Aqueous Lubricating Properties of Charged and Neutral Amphiphilic Diblock Copolymers at a Compliant, Hydrophobic Interface

DEFF Research Database (Denmark)

Røn, Troels; Javakhishvili, Irakli; Jankova Atanasova, Katja

2013-01-01

We have investigated the adsorption and lubricating properties of neutral and charged amphiphilic diblock copolymers at a hydrophobic polydimethylsiloxane (PDMS) interface in an aqueous environment. The diblock copolymers consist of a hydrophilic block of either neutral poly(ethylene glycol) (PEG......) or negatively charged poly(acrylic acid) (PAA) and of a hydrophobic block of polystyrene (PS) or poly(2-methoxyethyl acrylate) (PMEA), thus generating PEG-b-X or PAA-b-X, where X block is either PS or PMEA. The molecular weight ratios were roughly 1:1 with each block ca. 5 kDa. Comparing the neutral PEG...... effective adsorption only when PMEA was employed as the anchoring block. For PAA-b-PS, the poor adsorption properties are chiefly attributed to micellization due to the high interfacial tension between the PS core and water. The poor lubricating properties of PAA-b-PS diblock copolymer for a PDMS...

Fluorescent and colorimetric molecular recognition probe for hydrogen bond acceptors.

Science.gov (United States)

Pike, Sarah J; Hunter, Christopher A

2017-11-22

The association constants for formation of 1 : 1 complexes between a H-bond donor, 1-naphthol, and a diverse range of charged and neutral H-bond acceptors have been measured using UV/vis absorption and fluorescence emission titrations. The performance of 1-naphthol as a dual colorimetric and fluorescent molecular recognition probe for determining the H-bond acceptor (HBA) parameters of charged and neutral solutes has been investigated in three solvents. The data were employed to establish self-consistent H-bond acceptor parameters (β) for benzoate, azide, chloride, thiocyanate anions, a series of phosphine oxides, phosphate ester, sulfoxide and a tertiary amide. The results demonstrate both the transferability of H-bond parameters between different solvents and the utility of the naphthol-based dual molecular recognition probe to exploit orthogonal spectroscopic techniques to determine the HBA properties of neutral and charged solutes. The benzoate anion is the strongest HBA studied with a β parameter of 15.4, and the neutral tertiary amide is the weakest H-bond acceptor investigated with a β parameter of 8.5. The H-bond acceptor strength of the azide anion is higher than that of chloride (12.8 and 12.2 respectively), and the thiocyanate anion has a β value of 10.8 and thus is a significantly weaker H-bond acceptor than both the azide and chloride anions.

Topological structure of the space of phenotypes: the case of RNA neutral networks.

Directory of Open Access Journals (Sweden)

Jacobo Aguirre

Full Text Available The evolution and adaptation of molecular populations is constrained by the diversity accessible through mutational processes. RNA is a paradigmatic example of biopolymer where genotype (sequence and phenotype (approximated by the secondary structure fold are identified in a single molecule. The extreme redundancy of the genotype-phenotype map leads to large ensembles of RNA sequences that fold into the same secondary structure and can be connected through single-point mutations. These ensembles define neutral networks of phenotypes in sequence space. Here we analyze the topological properties of neutral networks formed by 12-nucleotides RNA sequences, obtained through the exhaustive folding of sequence space. A total of 4(12 sequences fragments into 645 subnetworks that correspond to 57 different secondary structures. The topological analysis reveals that each subnetwork is far from being random: it has a degree distribution with a well-defined average and a small dispersion, a high clustering coefficient, and an average shortest path between nodes close to its minimum possible value, i.e. the Hamming distance between sequences. RNA neutral networks are assortative due to the correlation in the composition of neighboring sequences, a feature that together with the symmetries inherent to the folding process explains the existence of communities. Several topological relationships can be analytically derived attending to structural restrictions and generic properties of the folding process. The average degree of these phenotypic networks grows logarithmically with their size, such that abundant phenotypes have the additional advantage of being more robust to mutations. This property prevents fragmentation of neutral networks and thus enhances the navigability of sequence space. In summary, RNA neutral networks show unique topological properties, unknown to other networks previously described.

Net neutrality and audiovisual services

OpenAIRE

van Eijk, N.; Nikoltchev, S.

2011-01-01

Net neutrality is high on the European agenda. New regulations for the communication sector provide a legal framework for net neutrality and need to be implemented on both a European and a national level. The key element is not just about blocking or slowing down traffic across communication networks: the control over the distribution of audiovisual services constitutes a vital part of the problem. In this contribution, the phenomenon of net neutrality is described first. Next, the European a...

Electromagnetic trapping of neutral atoms

International Nuclear Information System (INIS)

Metcalf, H.J.

1986-01-01

Cooling and trapping of neutral atoms is a new branch of applied physics that has potential for application in many areas. The authors present an introduction to laser cooling and magnetic trapping. Some basic ideas and fundamental limitations are discussed, and the first successful experiments are reviewed. Trapping a neutral object depends on the interaction between an inhomogeneous electromagnetic field and a multiple moment that results in the exchange of kinetic for potential energy. In neutral atom traps, the potential energy must be stored as internal atomic energy, resulting in two immediate and extremely important consequences. First, the atomic energy levels will necessarily shift as the atoms move in the trap, and, second, practical traps for ground state neutral atoms atr necessarily very shallow compared to thermal energy. This small depth also dictates stringent vacuum requirements because a trapped atom cannot survive a single collision with a thermal energy background gas molecule. Neutral trapping, therefore, depends on substantial cooling of a thermal atomic sample and is inextricably connected with the cooling process

Plasma neutralizers for H- or D- beams

International Nuclear Information System (INIS)

Berkner, K.H.; Pyle, R.V.; Savas, S.E.; Stalder, K.R.

1980-10-01

Plasma neutralizers can produce higher conversion efficiencies than are obtainable with gas neutralizers for the production of high-energy neutral beams from negative hydrogen ions. Little attention has been paid to experimental neutralizer studies because of the more critical problems connected with the development of negative-ion sources. With the prospect of accelerating ampere dc beams from extrapolatable ion sources some time next year, we are re-examining plasma neutralizers. Some basic considerations, two introductory experiments, and a next-step experiment are described

Ion-beam Plasma Neutralization Interaction Images

Energy Technology Data Exchange (ETDEWEB)

Igor D. Kaganovich; Edward Startsev; S. Klasky; Ronald C. Davidson

2002-04-09

Neutralization of the ion beam charge and current is an important scientific issue for many practical applications. The process of ion beam charge and current neutralization is complex because the excitation of nonlinear plasma waves may occur. Computer simulation images of plasma neutralization of the ion beam pulse are presented.

Ion-beam Plasma Neutralization Interaction Images

International Nuclear Information System (INIS)

Igor D. Kaganovich; Edward Startsev; S. Klasky; Ronald C. Davidson

2002-04-01

Neutralization of the ion beam charge and current is an important scientific issue for many practical applications. The process of ion beam charge and current neutralization is complex because the excitation of nonlinear plasma waves may occur. Computer simulation images of plasma neutralization of the ion beam pulse are presented

New insights on the collisional escape of light neutrals from Mars

Science.gov (United States)

Gacesa, Marko; Zahnle, Kevin

2017-04-01

Photodissociative recombination (PDR) of atmospheric molecules on Mars is a major mechanism of production of hot (suprathermal) atoms with sufficient kinetic energy to either directly escape to space or to eject other atmospheric species. This collisional ejection mechanism is important for evaluating the escape rates of all light neutrals that are too heavy to escape via Jeans escape. In particular, it plays a role in estimating the total volume of escaped water constituents (i.e., O and H) from Mars, as well as influences evolution of the atmospheric [D]/[H] ratio1. We present revised estimates of total collisional escape rates of neutral light elements including H, He, and H2, based on recent (years 2015-2016) atmospheric density profiles obtained from the NASA Mars Atmosphere and Volatile Evolution (MAVEN) mission. We also estimate the contribution to the collisional escape from Energetic Neutral Atoms (ENAs) produced in charge-exchange of solar wind H+ and He+ ions with atmospheric gases2,3. Scattering of hot oxygen and atmospheric species of interest is modeled using fully-quantum reactive scattering formalism1,3. The escape rates are evaluated using a 1D model of the atmosphere supplemented with MAVEN measurements of the neutrals. Finally, new estimates of contributions of these non-thermal mechanisms to the estimated PDR escape rates from young Mars4 are presented. [1] M. Gacesa and V. Kharchenko, "Non-thermal escape of molecular hydrogen from Mars", Geophys. Res. Lett., 39, L10203 (2012). [2] N. Lewkow and V. Kharchenko, "Precipitation of Energetic Neutral Atoms and Escape Fluxes induced from the Mars Atmosphere", Astroph. J., 790, 98 (2014). [3] M. Gacesa, N. Lewkow, and V. Kharchenko, "Non-thermal production and escape of OH from the upper atmosphere of Mars", Icarus 284, 90 (2017). [4] J. Zhao, F. Tian, Y. Ni, and X. Huang, "DR-induced escape of O and C from early Mars", Icarus 284, 305 (2017).

Evolutionary constraints and the neutral theory. [mutation-caused nucleotide substitutions in DNA

Science.gov (United States)

Jukes, T. H.; Kimura, M.

1984-01-01

The neutral theory of molecular evolution postulates that nucleotide substitutions inherently take place in DNA as a result of point mutations followed by random genetic drift. In the absence of selective constraints, the substitution rate reaches the maximum value set by the mutation rate. The rate in globin pseudogenes is about 5 x 10 to the -9th substitutions per site per year in mammals. Rates slower than this indicate the presence of constraints imposed by negative (natural) selection, which rejects and discards deleterious mutations.

Tax Neutrality on International Capital Investments

Directory of Open Access Journals (Sweden)

Gizem KAPUCU

2017-07-01

Full Text Available The tax policies which states follow with regard to developing technology and capital investments with raising mobility due to globalism are need to be discussed in its legal basis. The principle of tax neutrality has the aim of being legal foundation for these policies. According to this, the neutrality principle in taxation of international capital investments is provided with two measures, namely; not effecting the investment decision and not discriminate between investments. In this paper, initially focused on the conceptual framework and the foundations of the tax neutrality principle and later capital export neutrality and capital import neutrality are considered and explained with regard to international capital movements. Moreover, conformity and diversion to the principle of the current situation and regulations in OECD, EU and Turkey are examined.

Extended Lagrangian formulation of charge-constrained tight-binding molecular dynamics.

Science.gov (United States)

Cawkwell, M J; Coe, J D; Yadav, S K; Liu, X-Y; Niklasson, A M N

2015-06-09

The extended Lagrangian Born-Oppenheimer molecular dynamics formalism [Niklasson, Phys. Rev. Lett., 2008, 100, 123004] has been applied to a tight-binding model under the constraint of local charge neutrality to yield microcanonical trajectories with both precise, long-term energy conservation and a reduced number of self-consistent field optimizations at each time step. The extended Lagrangian molecular dynamics formalism restores time reversal symmetry in the propagation of the electronic degrees of freedom, and it enables the efficient and accurate self-consistent optimization of the chemical potential and atomwise potential energy shifts in the on-site elements of the tight-binding Hamiltonian that are required when enforcing local charge neutrality. These capabilities are illustrated with microcanonical molecular dynamics simulations of a small metallic cluster using an sd-valent tight-binding model for titanium. The effects of weak dissipation on the propagation of the auxiliary degrees of freedom for the chemical potential and on-site Hamiltonian matrix elements that is used to counteract the accumulation of numerical noise during trajectories was also investigated.

The Net Neutrality Debate: The Basics

Science.gov (United States)

Greenfield, Rich

2006-01-01

Rich Greenfield examines the basics of today's net neutrality debate that is likely to be an ongoing issue for society. Greenfield states the problems inherent in the definition of "net neutrality" used by Common Cause: "Network neutrality is the principle that Internet users should be able to access any web content they choose and…

Neutral particle kinetics in fusion devices

International Nuclear Information System (INIS)

Tendler, M.; Heifetz, D.

1986-05-01

The theory of neutral particle kinetics treats the transport of mass, momentum, and energy in a plasma due to neutral particles which themselves are unaffected by magnetic fields. This transport affects the global power and particle balances in fusion devices, as well as profile control and plasma confinement quality, particle and energy fluxes onto device components, performance of pumping systems, and the design of diagnostics and the interpretation of their measurements. This paper reviews the development of analytic, numerical, and Monte Carlo methods of solving the time-independent Boltzmann equation describing neutral kinetics. These models for neutral particle behavior typically use adaptations of techniques developed originally for computing neutron transport, due to the analogy between the two phenomena, where charge-exchange corresponds to scattering and ionization to absorption. Progress in the field depends on developing multidimensional analytic methods, and obtaining experimental data for the physical processes of wall reflection, the neutral/plasma interaction, and for processes in fusion devices which are directly related to neutral transport, such as H/sub α/ emission rates, plenum pressures, and charge-exchange emission spectra

Neutral particle kinetics in fusion devices

Energy Technology Data Exchange (ETDEWEB)

Tendler, M.; Heifetz, D.

1986-05-01

The theory of neutral particle kinetics treats the transport of mass, momentum, and energy in a plasma due to neutral particles which themselves are unaffected by magnetic fields. This transport affects the global power and particle balances in fusion devices, as well as profile control and plasma confinement quality, particle and energy fluxes onto device components, performance of pumping systems, and the design of diagnostics and the interpretation of their measurements. This paper reviews the development of analytic, numerical, and Monte Carlo methods of solving the time-independent Boltzmann equation describing neutral kinetics. These models for neutral particle behavior typically use adaptations of techniques developed originally for computing neutron transport, due to the analogy between the two phenomena, where charge-exchange corresponds to scattering and ionization to absorption. Progress in the field depends on developing multidimensional analytic methods, and obtaining experimental data for the physical processes of wall reflection, the neutral/plasma interaction, and for processes in fusion devices which are directly related to neutral transport, such as H/sub ..cap alpha../ emission rates, plenum pressures, and charge-exchange emission spectra.

ORNL neutral gas shielding model for pellet-plasma interactions

International Nuclear Information System (INIS)

Milora, S.L; Foster, C.A.

1977-05-01

A revised neutral molecule ablation model is derived to describe the evaporation of a solid hydrogen pellet in a tokamak plasma. The approach taken is based on the theory of Parks, Turnbull, and Foster who postulate that a cloud of molecular hydrogen surrounding the pellet shields the surface from incoming energetic electrons and, in so doing, regulates the evaporation rate. This treatment differs from an earlier model in that the hydrodynamic behavior of the molecular cloud is treated in a self-consistent manner. Numerical solutions of the fluid dynamic equations, which include the effects of strong electron heating locally in the gas, reveal that the flow of material away from the pellet is initially retarded by the heating and then rapidly accelerated and rarefied. This behavior is more pronounced for higher temperature plasmas and the net effect is that pellet lifetimes are prolonged slightly by including the heating effects. A comparison is made with the results of the recent pellet injection experiments on ORMAK and a simple injection depth scaling law is derived

Neutral beam program

International Nuclear Information System (INIS)

Anon.

1979-01-01

The structure of the beam injection program for the Doublet-3 device is discussed. The design considerations for the beam line and design parameters for the Doublet-3 ion souce are given. Major components of the neutral beam injector system are discussed in detail. These include the neutralizer, magnetic shielding, reflecting magnets, vacuum system, calorimeter and beam dumps, and drift duct. The planned location of the two-injector system for Doublet-3 is illustrated and site preparation is considered. The status of beamline units 1 and 2 and the future program schedule are discussed

Role of neutral ceramidase in colon cancer.

Science.gov (United States)

García-Barros, Mónica; Coant, Nicolas; Kawamori, Toshihiko; Wada, Masayuki; Snider, Ashley J; Truman, Jean-Philip; Wu, Bill X; Furuya, Hideki; Clarke, Christopher J; Bialkowska, Agnieszka B; Ghaleb, Amr; Yang, Vincent W; Obeid, Lina M; Hannun, Yusuf A

2016-12-01

Alterations in sphingolipid metabolism, especially ceramide and sphingosine 1-phosphate, have been linked to colon cancer, suggesting that enzymes of sphingolipid metabolism may emerge as novel regulators and targets in colon cancer. Neutral ceramidase (nCDase), a key enzyme in sphingolipid metabolism that hydrolyzes ceramide into sphingosine, is highly expressed in the intestine; however, its role in colon cancer has not been defined. Here we show that molecular and pharmacological inhibition of nCDase in colon cancer cells increases ceramide, and this is accompanied by decreased cell survival and increased apoptosis and autophagy, with minimal effects on noncancerous cells. Inhibition of nCDase resulted in loss of β-catenin and inhibition of ERK, components of pathways relevant for colon cancer development. Furthermore, inhibition of nCDase in a xenograft model delayed tumor growth and increased ceramide while decreasing proliferation. It is noteworthy that mice lacking nCDase treated with azoxymethane were protected from tumor formation. Taken together, these studies show that nCDase is pivotal for regulating initiation and development of colon cancer, and these data suggest that this enzyme is a suitable and novel target for colon cancer therapy.-García-Barros, M., Coant, N., Kawamori, T., Wada, M., Snider, A. J., Truman, J.-P., Wu, B. X., Furuya, H., Clarke, C. J., Bialkowska, A. B., Ghaleb, A., Yang, V. W., Obeid, L. M., Hannun, Y. A. Role of neutral ceramidase in colon cancer. © FASEB.

Neutral Loss Scan - Based Strategy for Integrated Identification of Amorfrutin Derivatives, New Peroxisome Proliferator-Activated Receptor Gamma Agonists, from Amorpha Fruticosa by UPLC-QqQ-MS/MS and UPLC-Q-TOF-MS.

Science.gov (United States)

Chen, Chu; Xue, Ying; Li, Qing-Miao; Wu, Yan; Liang, Jian; Qing, Lin-Sen

2018-04-01

Amorfrutins with a 2-hydroxybenzoic acid core structure are promising natural PPARγ agonists with potent antidiabetic activity. Owing to the complex matrix and low concentration in botanical material, the identification of unknown amorfrutins remains a challenge. In the present study, a combined application of UPLC-Q-TOF-MS and UPLC-QqQ-MS was developed to discover unknown amorfrutins from fruits of Amorpha fruticosa. First, reference compounds of amorfrutin A (AA), amorfrutin B (AB), and 2-carboxy-3,5-dihydroxy-4-geranylbibenzyl (AC) were analyzed using UPLC-Q-TOF-MS to reveal the characteristic fragment ions and the possible neutral loss. Second, the extract of A. fruticosa was separated and screened by UPLC-QqQ-MS using neutral loss scan to find out suspect compounds associated with the specified neutral fragment Δm/z 44. Third, the extract was re-analyzed by UPLC-Q-TOF-MS to obtain the exact mass of quasi-molecular ion and fragment ions of each suspect compound, and to subsequently calculate their corresponding molecular formulas. Finally, according to the molecular formula of suspect compound and its fragment ions and comparing with literature data, structure elucidation of four unidentified amorfrutins was achieved. The results indicated that the combination of QqQ-MS neutral loss scan and Q-TOF-MS molecular formula calculation was proven to be a powerful tool for unknown natural product identification, and this strategy provides an effective solution to discover natural products or metabolites of trace content. Graphical Abstract ᅟ.

ORNL neutral-beam program in 1978

International Nuclear Information System (INIS)

Whealton, J.H.

1982-12-01

This report was presented at the ion source workshop held at Culham Laboratory, Abingdon, Oxfordshire, in 1978. Because the proceedings of that conference are unavailable, and because the material in this report is still not to be found elsewhere, it is issued as a laboratory report. The neutral beam group at Oak Ridge National Laboratory has constructed neutral beam generators for the ORMAK and PLT devices, is presently constructing neutral beam devices for the ISX and PDX devices, and is contemplating the construction of neutral beam systems for the advanced TNS device. These neutral beam devices stem from the pioneering work on ion sources of G.G. Kelley and O.B. Morgan. We describe the ion sources under development at this laboratory, the beam optics exhibited by these sources, as well as some theoretical considerations, and finally the remainder of the beamline design

Molecular beam kinetics

International Nuclear Information System (INIS)

Behrens, R. Jr.

1975-11-01

The design of a crossed molecular beam ''supermachine'' for neutral--neutral collisions is discussed. The universal electron bombardment ionizer, mass filter, and ion detection system of the detector, the supersonic nozzle sources, the differential pumping arrangement for the sources and detector, the time-of-flight detection of scattered products, and the overall configuration of the apparatus are described. The elastic scattering of two systems, CH 4 + Ar and NH 3 + Ar, has been measured using the supermachine with two supersonic nozzle sources. The rainbow structure and the interference oscillations are seen in each system. The best fit to the data was found using a Morse--Spline--Van der Waals (MSV) potential. The three potential parameters epsilon, r/sub m/, and β were found to be 2.20(+-0.04) x 10 -14 ergs, 3.82(+-0.04)A, and 7.05 +- 0.20 for CH 4 + Ar, and 2.21(+-0.04) x 10 -14 ergs 3.93 (+-0.05)A, and 8.45 +- 0.30 for NH 3 + Ar. A new phenomenon in crossed molecular beams of condensation of a molecule on a cluster to form a complex was observed. A bromine molecule condensed on clusters of chlorine (Cl 2 )/sub chi/ and ammonia (NH 3 )/sub chi/. The value of chi for measurements in these experiments ranges from 7 to 40 for chlorine clusters and from 10 to 70 ammonia clusters

Overview of the JET Neutral Beam Enhancement Project

International Nuclear Information System (INIS)

Ciric, D.

2006-01-01

Three objectives of the JET Neutral Beam Enhancement (NBE) are a) to increase the NB power delivered to JET from 25 MW to >34 MW; b) to extend the beam pulse duration from 10 to 20 seconds and c) to improve availability and reliability of the JET NB system. The project is based on the upgrade of the two existing JET neutral injectors, each equipped with eight positive ion neutral injectors (PINIs). The main increase of the NB power will come from the rearrangement of the ion source permanent magnets from the present supercusp to pure chequerboard configuration, thus eliminating the magnetic filter used to limit primary electrons reaching the extraction region. This modification considerably increases the fraction of molecular ions, which leads to higher neutralisation efficiency. Further increase in the injected neutral beam power will result from higher beam transmission, the consequence of high uniformity and superior properties of the beams extracted from chequerboard ion sources. Finally, the maximum extracted deuterium ion current will be increased from the present ∼ 55 A to ∼ 65 A. This will be accomplished by the minor modification of the extraction aperture diameter and the accelerator gap. All PINIs will be operated at the same acceleration voltage (125 kV). The increase of the beam pulse length from 10 to 20 seconds requires modification or replacement of inter-pulse water cooled beamline components. The most challenging among these tasks is the replacement the duct liner, which protects the vessel from re-ionised beam power at the beam entry into the torus. It will be replaced with an actively cooled liner based on proven hypervapotron technology. To improve the overall reliability of the JET neutral beam system and to allow extraction of 65 A of deuterium ion current, eight existing 80 kV/60 A high voltage power supplies (HVPS) will be replaced with four new 130 kV/130 A units. This means that, after the completion of the NBE project, 75% of the JET

Protonation-induced ultrafast torsional dynamics in 9-anthrylbenzimidazole: a pH activated molecular rotor.

Science.gov (United States)

Nandi, Amitabha; Kushwaha, Archana; Das, Dipanwita; Ghosh, Rajib

2018-03-07

We report the photophysical properties and excited state dynamics of 9-anthrylbenzimidazole (ANBI) which exhibits protonation-induced molecular rotor properties. In contrast to the highly emissive behavior of neutral ANBI, protonation of the benzimidazole group of ANBI induces efficient nonradiative deactivation by ultrafast torsional motion around the bond connecting the anthracene and benzimidazole units, as revealed by ultrafast transient absorption and fluorescence spectroscopy. Contrary to viscosity-independent fluorescence of neutral dyes, protonated ANBI is shown to display linear variation of emission yield and lifetime with solvent viscosity. The protonation-induced molecular rotor properties in the studied system are shown to be driven by enhanced charge transfer and are corroborated by quantum chemical calculations. Potential application as a microviscosity sensor of acidic regions in a heterogeneous environment by these proton-activated molecular rotor properties of ANBI is discussed.

Neutral-beam current drive in tokamaks

International Nuclear Information System (INIS)

Devoto, R.S.

1986-01-01

The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500 to 700 keV are needed for this device

Neutral-beam current drive in tokamaks

International Nuclear Information System (INIS)

Devoto, R.S.

1987-01-01

The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500-700 keV are needed for this device

Neutral beam in ALVAND IIC tokamak

International Nuclear Information System (INIS)

Ghrannevisse, M.; Moradshahi, M.; Avakian, M.

1992-01-01

Neutral beams have a wide application in tokamak experiments. It used to heat; fuel; adjust electric potentials in plasmas and diagnose particles densities and momentum distributions. It may be used to sustain currents in tokamaks to extend the pulse length. A 5 KV; 500 mA ion source has been constructed by plasma physics group, AEOI and it used to produce plasma and study the plasma parameters. Recently this ion source has been neutralized and it adapted to a neutral beam source; and it used to heat a cylindrical DC plasma and the plasma of ALVAND IIC Tokamak which is a small research tokamak with a minor radius of 12.6 cm, and a major radius of 45.5 cm. In this paper we report the neutralization of the ion beam and the results obtained by injection of this neutral beam into plasmas. (author) 2 refs., 4 figs

Structural Basis for Differential Neutralization of Ebolaviruses

Directory of Open Access Journals (Sweden)

John M. Dye

2012-04-01

Full Text Available There are five antigenically distinct ebolaviruses that cause hemorrhagic fever in humans or non-human primates (Ebola virus, Sudan virus, Reston virus, Taï Forest virus, and Bundibugyo virus. The small handful of antibodies known to neutralize the ebolaviruses bind to the surface glycoprotein termed GP1,2. Curiously, some antibodies against them are known to neutralize in vitro but not protect in vivo, whereas other antibodies are known to protect animal models in vivo, but not neutralize in vitro. A detailed understanding of what constitutes a neutralizing and/or protective antibody response is critical for development of novel therapeutic strategies. Here, we show that paradoxically, a lower affinity antibody with restricted access to its epitope confers better neutralization than a higher affinity antibody against a similar epitope, suggesting that either subtle differences in epitope, or different characteristics of the GP1,2 molecules themselves, confer differential neutralization susceptibility. Here, we also report the crystal structure of trimeric, prefusion GP1,2 from the original 1976 Boniface variant of Sudan virus complexed with 16F6, the first antibody known to neutralize Sudan virus, and compare the structure to that of Sudan virus, variant Gulu. We discuss new structural details of the GP1-GP2 clamp, thermal motion of various regions in GP1,2 across the two viruses visualized, details of differential interaction of the crystallized neutralizing antibodies, and their relevance for virus neutralization.

Identification and validation of a linear protective neutralizing epitope in the β-pore domain of alpha toxin.

Science.gov (United States)

Oscherwitz, Jon; Cease, Kemp B

2015-01-01

The plethora of virulence factors associated with Staphylococcus aureus make this bacterium an attractive candidate for a molecularly-designed epitope-focused vaccine. This approach, which necessitates the identification of neutralizing epitopes for incorporation into a vaccine construct, is being evaluated for pathogens where conventional approaches have failed to elicit protective humoral responses, like HIV-1 and malaria, but may also hold promise for pathogens like S. aureus, where the elicitation of humoral immunity against multiple virulence factors may be required for development of an effective vaccine. Among the virulence factors employed by S. aureus, animal model and epidemiological data suggest that alpha toxin, a multimeric β-pore forming toxin like protective antigen from Bacillus anthracis, is particularly critical, yet no candidate neutralizing epitopes have been delineated in alpha toxin to date. We have previously shown that a linear determinant in the 2β2-2β3 loop of the pore forming domain of B. anthracis protective antigen is a linear neutralizing epitope. Antibody against this site is highly potent for neutralizing anthrax lethal toxin in vitro and for protection of rabbits in vivo from virulent B. anthracis. We hypothesized that sequences in the β-pore of S. aureus alpha toxin that share structural and functional homology to β-pore sequences in protective antigen would contain a similarly critical neutralizing epitope. Using an in vivo mapping strategy employing peptide immunogens, an optimized in vitro toxin neutralization assay, and an in vivo dermonecrosis model, we have now confirmed the presence of this epitope in alpha toxin, termed the pore neutralizing determinant. Antibody specific for this determinant neutralizes alpha toxin in vitro, and is highly effective for mitigating dermonecrosis and bacterial growth in a mouse model of S. aureus USA300 skin infection. The delineation of this linear neutralizing determinant in alpha

Identification and validation of a linear protective neutralizing epitope in the β-pore domain of alpha toxin.

Directory of Open Access Journals (Sweden)

Jon Oscherwitz

Full Text Available The plethora of virulence factors associated with Staphylococcus aureus make this bacterium an attractive candidate for a molecularly-designed epitope-focused vaccine. This approach, which necessitates the identification of neutralizing epitopes for incorporation into a vaccine construct, is being evaluated for pathogens where conventional approaches have failed to elicit protective humoral responses, like HIV-1 and malaria, but may also hold promise for pathogens like S. aureus, where the elicitation of humoral immunity against multiple virulence factors may be required for development of an effective vaccine. Among the virulence factors employed by S. aureus, animal model and epidemiological data suggest that alpha toxin, a multimeric β-pore forming toxin like protective antigen from Bacillus anthracis, is particularly critical, yet no candidate neutralizing epitopes have been delineated in alpha toxin to date. We have previously shown that a linear determinant in the 2β2-2β3 loop of the pore forming domain of B. anthracis protective antigen is a linear neutralizing epitope. Antibody against this site is highly potent for neutralizing anthrax lethal toxin in vitro and for protection of rabbits in vivo from virulent B. anthracis. We hypothesized that sequences in the β-pore of S. aureus alpha toxin that share structural and functional homology to β-pore sequences in protective antigen would contain a similarly critical neutralizing epitope. Using an in vivo mapping strategy employing peptide immunogens, an optimized in vitro toxin neutralization assay, and an in vivo dermonecrosis model, we have now confirmed the presence of this epitope in alpha toxin, termed the pore neutralizing determinant. Antibody specific for this determinant neutralizes alpha toxin in vitro, and is highly effective for mitigating dermonecrosis and bacterial growth in a mouse model of S. aureus USA300 skin infection. The delineation of this linear neutralizing

The merits of neutral theory

NARCIS (Netherlands)

Alonso, D.; Etienne, R.S.; McKane, A.J.

2006-01-01

Hubbell's neutral theory of biodiversity has challenged the classic niche-based view of ecological community structure. Although there have been many attempts to falsify Hubbell's theory, we argue that falsification should not lead to rejection, because there is more to the theory than neutrality

Mutation exposed: a neutral explanation for extreme base composition of an endosymbiont genome.

Science.gov (United States)

Wernegreen, Jennifer J; Funk, Daniel J

2004-12-01

The influence of neutral mutation pressure versus selection on base composition evolution is a subject of considerable controversy. Yet the present study represents the first explicit population genetic analysis of this issue in prokaryotes, the group in which base composition variation is most dramatic. Here, we explore the impact of mutation and selection on the dynamics of synonymous changes in Buchnera aphidicola, the AT-rich bacterial endosymbiont of aphids. Specifically, we evaluated three forms of evidence. (i) We compared the frequencies of directional base changes (AT-->GC vs. GC-->AT) at synonymous sites within and between Buchnera species, to test for selective preference versus effective neutrality of these mutational categories. Reconstructed mutational changes across a robust intraspecific phylogeny showed a nearly 1:1 AT-->GC:GC-->AT ratio. Likewise, stationarity of base composition among Buchnera species indicated equal rates of AT-->GC and GC-->AT substitutions. The similarity of these patterns within and between species supported the neutral model. (ii) We observed an equivalence of relative per-site AT mutation rate and current AT content at synonymous sites, indicating that base composition is at mutational equilibrium. (iii) We demonstrated statistically greater equality in the frequency of mutational categories in Buchnera than in parallel mammalian studies that documented selection on synonymous sites. Our results indicate that effectively neutral mutational pressure, rather than selection, represents the major force driving base composition evolution in Buchnera. Thus they further corroborate recent evidence for the critical role of reduced N(e) in the molecular evolution of bacterial endosymbionts.

Crystallographic and magnetic properties of the spinel-type ferrites ZnxCo1-xFe2O4 (0.0 ≤ x ≤ 0.75)

Science.gov (United States)

Azad, A. K.; Zakaria, A. K. M.; Jewel, Md. Yusuf; Khan, Abu Saeed; Yunus, S. M.; Kamal, I.; Datta, T. K.; Eriksson, S.-G.

2015-05-01

Ultrahigh frequencies (UHF) have applications in signal and power electronics to minimize product sizes, increase production quantity and lower manufacturing cost. In the UHF range of 300 MHz to 3 GHz, ferrimagnetic iron oxides (ferrites) are especially useful because they combine the properties of a magnetic material with that of an electrical insulator. Ferrites have much higher electrical resistivity than metallic ferromagnetic materials, resulting in minimization of the eddy current losses, and total penetration of the electromagnetic (EM) field. Hence ferrites are frequently applied as circuit elements, magnetic storage media like read/write heads, phase shifters and Faraday rotators. The electromagnetic properties of ferrites are affected by operating conditions such as field strength, temperature and frequency. The spinel system ZnxCo1-xFe2O4 (x=0.0, 0.25, 0.50 and 0.75) has been prepared by the standard solid state sintering method. X-ray and neutron powder diffraction measurements were performed at room temperature. Neutron diffraction data analysis confirms the cubic symmetry corresponding to the space group Fd3m. The distribution of three cations Zn2+, Co2+ and Fe3+ over the spinel lattice and other crystallographic parameters like lattice constant, oxygen position parameter, overall temperature factor and occupancies of different ions in different lattice sites for the samples have been determined from the analysis of neutron diffraction data. The lattice constant increases with increasing Zn content in the system. The magnetic structure was found to be ferrimagnetic for the samples with x≤0.50. Magnetization measurements show that with the increase of Zn content in the system the value of saturation magnetization first increases and then decreases. The variation of the magnetic moment with Zn substitution has been discussed in terms of the distribution of magnetic and non-magnetic ions over the A and B sub-lattices and their exchange coupling.

Investigation of fundamental physical properties of CdSiP{sub 2} and its application in solar cell devices by using (ZnX; X = Se, Te) buffer layers

Energy Technology Data Exchange (ETDEWEB)

Verma, A.S., E-mail: ajay_phy@rediffmail.com [Department of Physics, Banasthali Vidyapith, Rajasthan 304022 (India); Gautam, Ruchita; Singh, Pravesh [Department of Physics, Banasthali Vidyapith, Rajasthan 304022 (India); Department of Electronics and Communication, Krishna Institute of Engineering and Technology, Ghaziabad, Uttar Pradesh 201206 (India); Sharma, Sheetal [Department of Physics, Swami Premanand Mahavidyalaya, Mukerian, Punjab 144211 (India); Kumari, Sarita [Department of Physics, University of Rajasthan, Jaipur 302004 (India)

2016-03-15

Graphical abstract: - Highlights: • FP-LAPW method has been used to compute the solid state properties of CdSiP{sub 2}. • Electronic and optical properties reported by WIEN2K with recently developed mBJ potential. • The elastic and thermal properties were evaluated by first principles calculations. • Hardness was calculated for the first time at different temperature and pressure. • Solar cell devices with ZnSe/ZnTe buffer layers by simulated work. - Abstract: The first principles calculations were performed by the linearized augmented plane wave (LAPW) method as implemented in the WIEN2K code within the density functional theory to obtain the structural, electronic and optical properties of CdSiP{sub 2} in the body centered tetragonal (BCT) phase. The six elastic constants (C{sub 11}, C{sub 12}, C{sub 13}, C{sub 33}, C{sub 44} and C{sub 66}) and mechanical parameters were presented and compared with the available experimental data. The thermodynamic calculations within the quasi-harmonic approximation is used to give an accurate description of the pressure-temperature dependence of the thermal-expansion coefficient, bulk modulus, specific heat, Debye temperature, entropy Grüneisen parameters and hardness. Further, CdSiP{sub 2} solar cell devices have been modeled; device physics and performance parameters are analyzed for zinc chalcogenide (ZnX; X = Se, Te) buffer layers. Simulation results for CdSiP{sub 2} thin layer solar cell show the maximum efficiency (25.7%) with ZnSe as the buffer layer.

Neutral evolution of mutational robustness

NARCIS (Netherlands)

Nimwegen, Erik van; Crutchfield, James P.; Huynen, Martijn

1999-01-01

We introduce and analyze a general model of a population evolving over a network of selectively neutral genotypes. We show that the population s limit distribution on the neutral network is solely determined by the network topology and given by the principal eigenvector of the network

Nitrogen-neutrality: a step towards sustainability

Science.gov (United States)

Leip, Adrian; Leach, Allison; Musinguzi, Patrick; Tumwesigye, Trust; Olupot, Giregon; Tenywa, John Stephen; Mudiope, Joseph; Hutton, Olivia; Cordovil, Claudia M. d. S.; Bekunda, Mateete; Galloway, James

2014-11-01

We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, N-neutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US 3050 was collected from the participants and used to offset the conference’s N footprint by supporting the UN Millennium Village cluster Ruhiira in South-Western Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates.

Nitrogen-neutrality: a step towards sustainability

International Nuclear Information System (INIS)

Leip, Adrian; Leach, Allison; Hutton, Olivia; Galloway, James; Musinguzi, Patrick; Tumwesigye, Trust; Olupot, Giregon; Stephen Tenywa, John; Mudiope, Joseph; Cordovil, Claudia M d S; Bekunda, Mateete

2014-01-01

We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, N-neutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US$ 3050 was collected from the participants and used to offset the conference’s N footprint by supporting the UN Millennium Village cluster Ruhiira in South-Western Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates. (paper)

Heavy neutral leptons at FASER

Science.gov (United States)

Kling, Felix; Trojanowski, Sebastian

2018-05-01

We study the prospects for discovering heavy neutral leptons at Forward Search Experiment (FASER), the newly proposed detector at the LHC. Previous studies showed that a relatively small detector with ˜10 m length and ≲1 m2 cross sectional area can probe large unconstrained parts of parameter space for dark photons and dark Higgs bosons. In this work, we show that FASER will also be sensitive to heavy neutral leptons that have mixing angles with the active neutrinos that are up to an order of magnitude lower than current bounds. In particular, this is true for heavy neutral leptons produced dominantly in B -meson decays, in which case FASER's discovery potential is comparable to the proposed SHiP detector. We also illustrate how the search for heavy neutral leptons at FASER will be complementary to ongoing searches in high-pT experiments at the LHC and can shed light on the nature of dark matter and the process of baryogenesis in the early Universe.

The Neutral Interest Rate: Estimates for Chile

OpenAIRE

Rodrigo Fuentes S; Fabián Gredig U.

2008-01-01

To estimate the neutral real interest rate for Chile, we use a variety of methods that can be classified into three categories: those derived from economic theory, the neutral rate implicit in financial assets, and statistical procedures using macroeconomic data. We conclude that the neutral rate is not constant over time, but it is closely related with—though not equivalent to—the potential GDP growth rate. The application of the different methods yields fairly similar results. The neutral r...

BEAMS3D Neutral Beam Injection Model

Energy Technology Data Exchange (ETDEWEB)

Lazerson, Samuel

2014-04-14

With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.

Modeling Secondary Neutral Helium in the Heliosphere

International Nuclear Information System (INIS)

Müller, Hans-Reinhard; Möbius, Eberhard; Wood, Brian E.

2016-01-01

An accurate, analytic heliospheric neutral test-particle code for helium atoms from the interstellar medium (ISM) is coupled to global heliospheric models dominated by hydrogen and protons from the solar wind and the ISM. This coupling enables the forward-calculation of secondary helium neutrals from first principles. Secondaries are produced predominantly in the outer heliosheath, upwind of the heliopause, by charge exchange of helium ions with neutral atoms. The forward model integrates the secondary production terms along neutral trajectories and calculates the combined neutral helium phase space density in the innermost heliosphere where it can be related to in-situ observations. The phase space density of the secondary component is lower than that of primary neutral helium, but its presence can change the analysis of primaries and the ISM, and can yield valuable insight into the characteristics of the plasma in the outer heliosheath. (paper)

Neutral particle beam alternative concept for ITER

International Nuclear Information System (INIS)

Sedgley, D.; Brook, J.; Luzzi, T.; Deutsch, L.

1989-01-01

An analysis of an ITER neutral particle beam system is presented. The analysis covers the neutralizer, ion dumps, pumping, and geometric aspects. The US beam concept for ITER consists of three or four clusters of beamlines delivering approximately 80 MW total of 1.6-MeV deuterium to three or four reactor ports. Each cluster has three self-contained beamlines featuring plasma neutralizers and electrostatic ion dumps. In this study, each of the beamlines has two source assemblies with separate gas neutralizers and magnetic ion dumps. Deuterium is injected into the gas neutralizers by a separate system. Saddle-shaped copper coils augment the tokamak poloidal field to turn the charged particles into the ion dumps. The gas flow from the source, neutralizer, and ion dump is pumped by regenerable cryopanels. The effect of the port between the TF coils and the beam injection angle on the plasma footprint was studied

An experimenter's history of neutral currents

International Nuclear Information System (INIS)

Sciulli, F.

1979-01-01

The history of the experimental study of neutral currents, defined as the class of weak interactions engaged in by lepton pairs of net zero charge, is traced under the headings; historical motivations, experimental searches, first positive indications, neutral currents corroborated, neutrino experiments on neutral currents and some general experimental comments. It is concluded that the neutral current does exist and predicted on the basis of gauge theory ideas, and though to connect the weak and electromagnetic interactions, its very general experimental properties are quite consistent with those ideas. Among these are flavor conserving complicated isospin structure, complicated V, A structure and a structure which depends on the type (or quantum numbers) of the target. 50 references. (UK)

Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant

Directory of Open Access Journals (Sweden)

Hale Jennifer R

2011-05-01

Full Text Available Abstract Background Directed protein evolution has been used to modify protein activity and research has been carried out to enhance the production of high quality mutant libraries. Many theoretical approaches suggest that allowing a population to undergo neutral selection may be valuable in directed evolution experiments. Findings Here we report on an investigation into the value of neutral selection in a classical model system for directed evolution, the conversion of the E. coli β-glucuronidase to a β-galactosidase activity. We find that neutral selection, i.e. selection for retaining glucuronidase activity, can efficiently identify the majority of sites of mutation that have been identified as beneficial for galactosidase activity in previous experiments. Each variant demonstrating increased galactosidase activity identified by our neutral drift experiments contained a mutation at one of four sites, T509, S557, N566 or W529. All of these sites have previously been identified using direct selection for beta galactosidase activity. Conclusions Our results are consistent with others that show that a neutral selection approach can be effective in selecting improved variants. However, we interpret our results to show that neutral selection is, in this case, not a more efficient approach than conventional directed evolution approaches. However, the neutral approach is likely to be beneficial when the resulting library can be screened for a range of related activities. More detailed statistical studies to resolve the apparent differences between this system and others are likely to be a fruitful avenue for future research.

Computational study of the first stage of hypersonic ion beam neutralization: The cross neutralization stage

International Nuclear Information System (INIS)

Pomot, C.; Dolique, J.M.

1975-01-01

A study is made of the first stage of evolution of a hypersonic ion beam in which thermoelectrons are emitted by a heated grid, known as the neutralizer. Downstream from the neutralizer there appears successively as a sheath a range of periodic and quasi-stationary electric field and a front where the electric field oscillates with the plasma frequency. The sheath is self-regulated. Some electrons are trapped in the periodic and stationary electric field. The characteristics of the periodic, quasi-stationary range correspond to those of both an experimental study and one-dimensional time-independent macroscopic theory. This quasi-stationary regime builds up in a time smaller than ω/subp/e -1 and is studied for a few periods ω/subP//sube/ -1 . The subsequent evolution of this state of nonequilibrium is not investigated. The experimental study has shown that, as for the neutralization of a subsonic ion beam, it leads to a field-free, homogeneous medium: a ''synthesized plasma.'' The importance of the first stage described herein, which may be called the gross neutralization stage, is due to the properties of mean neutrality in the current and in the charge insured by the regulating sheath, properties which will be preseved downstream

Net neutrality and audiovisual services

NARCIS (Netherlands)

van Eijk, N.; Nikoltchev, S.

2011-01-01

Net neutrality is high on the European agenda. New regulations for the communication sector provide a legal framework for net neutrality and need to be implemented on both a European and a national level. The key element is not just about blocking or slowing down traffic across communication

Energizing and depletion of neutrals by a collisional plasma

International Nuclear Information System (INIS)

Fruchtman, A

2008-01-01

Neutral depletion can significantly affect the steady state of low temperature plasmas. Recent theoretical analyses predicted previously unexpected effects of neutral depletion in both collisional and collisionless regimes. In this paper we address the effect of the energy deposited in the neutral gas by a collisional plasma. The fraction of power deposited in the neutrals is shown to be independent of the amount of power. The first case we address is of a thermalized neutral gas. It is shown that a low heat conductivity of the neutral gas is followed by a high neutral temperature that results in a high neutral depletion even if the plasma pressure is small. In the second case neutrals are accelerated through charge exchange with ions leading to what we call neutral pumping, which is equivalent to ion pumping in a collisionless plasma. Neutral depletion is found in the second case for both a closed system (no net mass flow) and an open system (a finite mass flow). A thruster that employs a collisional plasma and pumped neutrals is compared with the thruster analyzed before that employs collisionless plasma.

Net Neutrality: Media Discourses and Public Perception

Directory of Open Access Journals (Sweden)

Christine Quail

2010-01-01

Full Text Available This paper analyzes media and public discourses surrounding net neutrality, with particular attention to public utility philosophy, from a critical perspective. The article suggests that further public education about net neutrality would be beneficial. The first portion of this paper provides a survey of the existing literature surrounding net neutrality, highlighting the contentious debate between market-based and public interest perspectives. In order to contextualize the debate, an overview of public utility philosophy is provided, shedding light on how the Internet can be conceptualized as a public good. Following this discussion, an analysis of mainstream media is presented, exploring how the media represents the issue of net neutrality and whether or not the Internet is discussed through the lens of public utility. To further examine how the net neutrality debate is being addressed, and to see the potential impacts of media discourses on the general public, the results of a focus group are reported and analyzed. Finally, a discussion assesses the implications of the net neutrality debate as presented through media discourses, highlighting the future of net neutrality as an important policy issue.

On implicit abstract neutral nonlinear differential equations

Energy Technology Data Exchange (ETDEWEB)

Hernández, Eduardo, E-mail: lalohm@ffclrp.usp.br [Universidade de São Paulo, Departamento de Computação e Matemática, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto (Brazil); O’Regan, Donal, E-mail: donal.oregan@nuigalway.ie [National University of Ireland, School of Mathematics, Statistics and Applied Mathematics (Ireland)

2016-04-15

In this paper we continue our developments in Hernández and O’Regan (J Funct Anal 261:3457–3481, 2011) on the existence of solutions for abstract neutral differential equations. In particular we extend the results in Hernández and O’Regan (J Funct Anal 261:3457–3481, 2011) for the case of implicit nonlinear neutral equations and we focus on applications to partial “nonlinear” neutral differential equations. Some applications involving partial neutral differential equations are presented.

A Measurement of Coherent Neutral Pion Production in Neutrino Neutral Current Interactions in NOMAD experiment

CERN Document Server

Kullenberg, C T

2009-01-01

We present a study of exclusive neutral pion production in neutrino-nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to $1.44 \\times 10^6$ muon-neutrino Charged Current interactions in the energy range $2.5 \\leq E_{\

Recent work with fast molecular-ion beams at Argonne National Laboratory

International Nuclear Information System (INIS)

Cooney, P.J.; Gemmell, D.S.; Groeneveld, K.O.; Kanter, E.P.; Pietsch, W.J.; Vager, Z.; Zabransky, B.J.

1979-01-01

Research in these areas during 1979 is summarized: (a) studies of molecular-ion dissociation in gaseous targets, (b) developing an understanding of the origins of central peaks and of the two phenomena of the transmission of fast molecular ions through thin foil targets and of the production of neutral fragments from collision-induced dissociation of fast molecular projectiles, (c) studies exploring the extent to which high-resolution measurements on dissociation fragments can be used to determine the stereochemical structures of the molecular ions in the incident beam, (d) extensive modifications to the beam-line and apparatus at the 4-MV Dynamitron so as to permit a wide variety of coincidence measurements on fragments from collision-induced molecular-ion dissociation

Design of the ITER Neutral Beam injectors

International Nuclear Information System (INIS)

Hemsworth, R.S.; Feist, J.; Hanada, M.; Heinemann, B.; Inoue, T.; Kuessel, E.; Kulygin, V.; Krylov, A.; Lotte, P.; Miyamoto, K.; Miyamoto, N.; Murdoch, D.; Nagase, A.; Ohara, Y.; Okumura, Y.; Pamela, J.; Panasenkov, A.; Shibata, K.; Tanii, M.

1996-01-01

This paper describes the Neutral Beam Injection system which is presently being designed in Europe, Japan and Russia, with co-ordination by the Joint Central Team of ITER at Naka, Japan. The proposed system consists of three negative ion based neutral injectors, delivering a total of 50 MW of 1 MeV D 0 to the ITER plasma for pulse length of ≥1000 s. The injectors each use a single caesiated volume arc discharge negative ion source, and a multi-grid, multi-aperture accelerator, to produce about 40 A of 1 MeV D - . This will be neutralized in a sub-divided gas neutralizer, which has a conversion efficiency of about 60%. The charged fraction of the beam emerging from the neutralizer is dumped in an electrostatic residual ion dump. A water cooled calorimeter can be moved into the beam path to intercept the neutral beam, allowing commissioning of the injector independent of ITER. copyright 1996 American Institute of Physics

Developing a molecular platform for potential carbon dioxide fixing

DEFF Research Database (Denmark)

Mikkelsen, Mette; Jørgensen, Mikkel; Krebs, Frederik C

2010-01-01

This paper presents an attempt to develop a new system for fixing carbon dioxide from the atmosphere. The proposed molecular system has been designed to have the capacity to spontaneously bind CO2 from the atmosphere with high affinity. The molecular system is furthermore designed to have...... the ability to liberate CO2 at a later stage in the process, i.e., in a separate compartment. The liberated CO2 presents a carbon neutral way of obtaining pure CO2. The proposed molecular system is based on a small stable organic molecule that potentially have two forms: one without bound CO2 and one...

Weak neutral-current interactions

International Nuclear Information System (INIS)

Barnett, R.M.

1978-08-01

The roles of each type of experiment in establishing uniquely the values of the the neutral-current couplings of u and d quarks are analyzed together with their implications for gauge models of the weak and electromagnetic interactions. An analysis of the neutral-current couplings of electrons and of the data based on the assumption that only one Z 0 boson exists is given. Also a model-independent analysis of parity violation experiments is discussed. 85 references

Transport of neutral atoms and molecules in TFCX

International Nuclear Information System (INIS)

Boley, C.D.

1984-09-01

The distribution of neutrals in the proposed reactor TFCX has been modeled by the 3-D Monte Carlo neutral transport code DEGAS, which has been run in conjunction with the 1-1/2-D time-dependent plasma transport code WHIST. The former code contains the best available treatment of neutral-particle physics, including a selection of wall reflection models. The latter code has a comprehensive set of plasma transport coefficients, an MHD equilibrium package, and provision for source terms such as those involving neutrals. It has a simple scrape-off model involving sound-speed flow to the neutralizer plates. The codes are run in iteration, so that the flux-surface averaged particle and energy sources due to interactions with neutrals are consistent with the plasma profiles. The design considered here has a bottom limiter with a pumping plenum. Results are given for the power balance, the mutually consistent plasma and neutral distributions set up in the edge region, the neutral density in the plenum, and the charge-exchange power deposition and erosion along the limiter

Divergence at neutral and non-neutral loci in Drosophila buzzatii populations and their hybrids

DEFF Research Database (Denmark)

Andersen, Ditte Holm; Pertoldi, Cino; Loeschcke, Volker

2008-01-01

The impact of intraspecific hybridisation on fitness and morphological traits depends on the history of natural selection and genetic drift, which may have led to differently coadapted gene-complexes in the parental populations. The divergence at neutral and non-neutral loci between populations can...... populations of Drosophila buzzatii, one between populations from Argentina and the Canary Islands (separated for 200 years), and the other between populations from Argentina and Australia (separated for 80 years). We observed the highest divergence at neutral loci between the Argentinean and Canary Island...

Intense ion beam neutralization using underdense background plasma

Energy Technology Data Exchange (ETDEWEB)

Berdanier, William [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Roy, Prabir K. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kaganovich, Igor [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

2015-01-15

Producing an overdense background plasma for neutralization purposes with a density that is high compared to the beam density is not always experimentally possible. We show that even an underdense background plasma with a small relative density can achieve high neutralization of intense ion beam pulses. Using particle-in-cell simulations, we show that if the total plasma electron charge is not sufficient to neutralize the beam charge, electron emitters are necessary for effective neutralization but are not needed if the plasma volume is so large that the total available charge in the electrons exceeds that of the ion beam. Several regimes of possible underdense/tenuous neutralization plasma densities are investigated with and without electron emitters or dense plasma at periphery regions, including the case of electron emitters without plasma, which does not effectively neutralize the beam. Over 95% neutralization is achieved for even very underdense background plasma with plasma density 1/15th the beam density. We compare results of particle-in-cell simulations with an analytic model of neutralization and find close agreement with the particle-in-cell simulations. Further, we show experimental data from the National Drift Compression experiment-II group that verifies the result that underdense plasma can neutralize intense heavy ion beams effectively.

Money neutrality: Rethinking the myth

Directory of Open Access Journals (Sweden)

Issaoui Fakhri

2015-01-01

Full Text Available Considered as an axiomatic basis of classical, neoclassical, and monetarist theories, the long-run money neutrality assumption does not always seem to be verified. Indeed, in our view, the money, in the sense of M2, can constitute a long-run channel of growth transmission. Thus, this paper examines the long-term relationship among money supply (M2, income (GDP, and prices (CPI. The subprime crisis in 2007 has shown that the demand for money does not only meet motives of transaction, precaution, and speculation but also of fictional or quasi-fictional future demands due to the fact that they are created without real counterparts. The capacity of production systems in developed countries to respond to increases in money supply by creating more wealth, involves the assumption of money neutrality in the long-run. However, in developing countries, the excess of money supply may lead to inflation trends. The present study has confirmed the long-term non-neutrality of money supply in the USA, and its neutrality in Gabon and Morocco.

Controllability Problem of Fractional Neutral Systems: A Survey

Directory of Open Access Journals (Sweden)

Artur Babiarz

2017-01-01

Full Text Available The following article presents recent results of controllability problem of dynamical systems in infinite-dimensional space. Generally speaking, we describe selected controllability problems of fractional order systems, including approximate controllability of fractional impulsive partial neutral integrodifferential inclusions with infinite delay in Hilbert spaces, controllability of nonlinear neutral fractional impulsive differential inclusions in Banach space, controllability for a class of fractional neutral integrodifferential equations with unbounded delay, controllability of neutral fractional functional equations with impulses and infinite delay, and controllability for a class of fractional order neutral evolution control systems.

Composition and strain effects in Type I and Type II heterostructure ZnSe/Cd(Zn)S and ZnSe/Cd1-xZnxS core/shell quantum dots

Science.gov (United States)

Gheshlaghi, Negar; Pisheh, Hadi Sedaghat; Ünlü, Hilmi

2017-11-01

We investigated the effect of ternary shell alloy composition on the bandgap and diameter of core of ZnSe / Cd1 - x Znx S heterostructure core/shell quantum dots, which were synthesized by using a simple colloidal technique. Characterization by using the x-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis absorption and fluorescence emission spectroscopic techniques indicate that (i) there is a transition of ZnSe / Cd0.6 Zn0.4 S Type-I heterostructure (electrons and holes tend to localize in core) to ZnSe / Cd0.75 Zn0.25 S quasi-Type-II heterostructures (holes tend to localized in the core and electrons are delocalized) and (ii) then after large red shift and Stock-shift in PL emission spectra but not a distinct absorption peak in UV spectra become noticeable in ZnSe/Cd0.75Zn0.25 S quasi-Type II and ZnSe/CdS Type II heterostructures (electrons are localized in core and holes are localized in shell). Furthermore, the increase of Cd:S ratio in shell alloy composition shifts the XRD peaks to lower 2θ degrees which corresponds to tensile strain in the ZnSe core. Finally, the hydrostatic interfacial strain has effect on the squeezing or stretching the capped core: A decrease of compressive force on core from ZnSe/ZnS to tensile force in ZnSe/CdS with increase in Cd:S ratio indicates that transition of compressive strain to tensile strain takes place with the transition from Type-I to II heterostructure.

Method to Minimize the Low-Frequency Neutral-Point Voltage Oscillations With Time-Offset Injection for Neutral-Point-Clamped Inverters

DEFF Research Database (Denmark)

Choi, Ui-Min; Blaabjerg, Frede; Lee, Kyo-Beum

2015-01-01

time of small- and medium-voltage vectors. However, if the power factor is lower, there is a limitation to eliminate neutral-point oscillations. In this case, the proposed method can be improved by changing the switching sequence properly. Additionally, a method for neutral-point voltage balancing......This paper proposes a method to reduce the low-frequency neutral-point voltage oscillations. The neutral-point voltage oscillations are considerably reduced by adding a time offset to the three-phase turn-on times. The proper time offset is simply calculated considering the phase currents and dwell...

LIAD-fs: A novel method for studies of ultrafast processes in gas phase neutral biomolecules

International Nuclear Information System (INIS)

Calvert, C R; Kelly, O; Duffy, M J; Belshaw, L; King, R B; Williams, I D; Greenwood, J B

2012-01-01

A new experimental technique for femtosecond (fs) pulse studies of gas phase biomolecules is reported. Using Laser-Induced Acoustic Desorption (LIAD) to produce a plume of neutral molecules, a time-delayed fs pulse is employed for ionisation/fragmentation, with subsequent products extracted and mass analysed electrostatically. By varying critical laser pulse parameters, this technique can be used to implement control over molecular fragmentation for a range of small biomolecules, with specific studies of amino acids demonstrated.

Neutrality in mediation: an ambiguous ethical value

OpenAIRE

Bailey, Paul

2014-01-01

Mediator neutrality would appear, by definition, to be a necessary and required ethical principle for all mediators to practice. But what is meant by neutrality in mediation? Is it practically possible to be completely neutral between parties in mediation while at the same time being fair to both of them? This paper attempts to answer these two questions.

Neutral-beam development plan, FY 1982-1987

International Nuclear Information System (INIS)

1981-09-01

The following chapters are included: (1) status of BNL negative ion source development, (2) source development program plan, (3) status of beam transport and acceleration, (4) accelerator development program plan, (5) neutralizer concepts, (6) neutralization program plan, (7) neutral beam systems, (8) test facilities, (9) program milestones and time schedules, (10) organization and Grumman participation, and (11) funding tables

ITER neutral beam system US conceptual design

International Nuclear Information System (INIS)

Purgalis, P.

1990-09-01

In this document we present the US conceptual design of a neutral beam system for International Thermonuclear Experimental Reactor (ITER). The design incorporates a barium surface conversion D - source feeding a linear array of accelerator channels. The system uses a dc accelerator with electrostatic quadrupoles for strong focusing. A high voltage power supply that is integrated with the accelerator is presented as an attractive option. A gas neutralizer is used and residual ions exiting the neutralizer are deflected to water-cooled dumps. Cryopanels are located at the accelerator exit to pump excess gas from the source and the neutralizer, and in the ion dump cavity to pump re-neutralized ions and neutralizer gas. All the above components are packaged in compact identical, independent modules which can be removed for remote maintenance. The neutral beam system delivers 75 MW of DO at 1.3 MeV, into three ports with a total of 9 modules arranged in stacks of three modules per port . To increase reliability each module is designed to deliver up to 10 MW; this allows eight modules operating at partial capacity to deliver the required power in the event one module is out of service, and provides 20% excess capacity to improve availability. Radiation protection is provided by shielding and by locating critical components in the source and accelerator 46.5 m from the torus centerline. Neutron shielding in the drift duct and neutralizer provides the added feature of limiting conductance and thus reducing gas flow to and from the torus

Hydro-chemical study of the evolution of interstellar pre-biotic molecules during the collapse of molecular clouds

International Nuclear Information System (INIS)

Majumdar, Liton; Das, Ankan; Chakrabarti, Sandip K.; Chakrabarti, Sonali

2012-01-01

One of the stumbling blocks for studying the evolution of interstellar molecules is the lack of adequate knowledge about the rate coefficients of various reactions which take place in the interstellar medium and molecular clouds. Some theoretical models of rate coefficients do exist in the literature for computing abundances of complex pre-biotic molecules. So far these have been used to study the abundances of these molecules in space. However, in order to obtain more accurate final compositions in these media, we have calculated the rate coefficients for the formation of some of the most important interstellar pre-biotic molecules by using quantum chemical theory. We use these rates inside our hydro-chemical model to examine the chemical evolution and final abundances of pre-biotic species during the collapsing phase of a proto-star. We find that a significant amount of various pre-biotic molecules could be produced during the collapse phase of a proto-star. We thoroughly study the formation of these molecules via successive neutral-neutral and radical-radical/radical-molecular reactions. We present the time evolution of the chemical species with an emphasis on how the production of these molecules varies with the depth of a cloud. We compare the formation of adenine in interstellar space using our rate-coefficients and using those obtained from existing theoretical models. Formation routes of the pre-biotic molecules are found to be highly dependent on the abundances of the reactive species and the rate coefficients involved in the reactions. The presence of grains strongly affects the abundances of the gas phase species. We also carry out a comparative study between different pathways available for the synthesis of adenine, alanine, glycine and other molecules considered in our network. Despite the huge abundances of the neutral reactive species, production of adenine is found to be strongly dominated by the radical-radical/radical-molecular reaction pathways

Neutral lipid-storage disease with myopathy and extended phenotype with novel PNPLA2 mutation.

Science.gov (United States)

Massa, Roberto; Pozzessere, Simone; Rastelli, Emanuele; Serra, Laura; Terracciano, Chiara; Gibellini, Manuela; Bozzali, Marco; Arca, Marcello

2016-04-01

Neutral lipid-storage disease with myopathy is caused by mutations in PNPLA2, which produce skeletal and cardiac myopathy. We report a man with multiorgan neutral lipid storage and unusual multisystem clinical involvement, including cognitive impairment. Quantitative brain MRI with voxel-based morphometry and extended neuropsychological assessment were performed. In parallel, the coding sequences and intron/exon boundaries of the PNPLA2 gene were screened by direct sequencing. Neuropsychological assessment revealed global cognitive impairment, and brain MRI showed reduced gray matter volume in the temporal lobes. Molecular characterization revealed a novel homozygous mutation in exon 5 of PNPLA2 (c.714C>A), resulting in a premature stop codon (p.Cys238*). Some PNPLA2 mutations, such as the one described here, may present with an extended phenotype, including brain involvement. In these cases, complete neuropsychological testing, combined with quantitative brain MRI, may help to characterize and quantify cognitive impairment. © 2016 Wiley Periodicals, Inc.

Active ion temperature measurement with heating neutral beam

International Nuclear Information System (INIS)

Miura, Yukitoshi; Matsuda, Toshiaki; Yamamoto, Shin

1987-03-01

When the heating neutral-beam (hydrogen beam) is injected into a deuterium plasma, the density of neutral particles is increased locally. By using this increased neutral particles, the local ion temperature is measured by the active charge-exchange method. The analyzer is the E//B type mass-separated neutral particle energy analyzer and the measured position is about one third outside of the plasma radius. The deuterium energy spectrum is Maxwellian, and the temperature is increased from 350 eV to 900 eV during heating. Since the local hydrogen to deuterium density concentration and the density of the heating neutral-beam as well as the ion temperature can be obtained good S/N ratio, the usefulness of this method during neutral-beam heating is confirmed by this experiment. (author)

Electron attenuation in free, neutral ethane clusters.

Science.gov (United States)

Winkler, M; Myrseth, V; Harnes, J; Børve, K J

2014-10-28

The electron effective attenuation length (EAL) in free, neutral ethane clusters has been determined at 40 eV kinetic energy by combining carbon 1s x-ray photoelectron spectroscopy and theoretical lineshape modeling. More specifically, theory is employed to form model spectra on a grid in cluster size (N) and EAL (λ), allowing N and λ to be determined by optimizing the goodness-of-fit χ(2)(N, λ) between model and observed spectra. Experimentally, the clusters were produced in an adiabatic-expansion setup using helium as the driving gas, spanning a range of 100-600 molecules in mean cluster size. The effective attenuation length was determined to be 8.4 ± 1.9 Å, in good agreement with an independent estimate of 10 Å formed on the basis of molecular electron-scattering data and Monte Carlo simulations. The aggregation state of the clusters as well as the cluster temperature and its importance to the derived EAL value are discussed in some depth.

Feline Immunodeficiency Virus (FIV Neutralization: A Review

Directory of Open Access Journals (Sweden)

Margaret J. Hosie

2011-10-01

Full Text Available One of the major obstacles that must be overcome in the design of effective lentiviral vaccines is the ability of lentiviruses to evolve in order to escape from neutralizing antibodies. The primary target for neutralizing antibodies is the highly variable viral envelope glycoprotein (Env, a glycoprotein that is essential for viral entry and comprises both variable and conserved regions. As a result of the complex trimeric nature of Env, there is steric hindrance of conserved epitopes required for receptor binding so that these are not accessible to antibodies. Instead, the humoral response is targeted towards decoy immunodominant epitopes on variable domains such as the third hypervariable loop (V3 of Env. For feline immunodeficiency virus (FIV, as well as the related human immunodeficiency virus-1 (HIV-1, little is known about the factors that lead to the development of broadly neutralizing antibodies. In cats infected with FIV and patients infected with HIV-1, only rarely are plasma samples found that contain antibodies capable of neutralizing isolates from other clades. In this review we examine the neutralizing response to FIV, comparing and contrasting with the response to HIV. We ask whether broadly neutralizing antibodies are induced by FIV infection and discuss the comparative value of studies of neutralizing antibodies in FIV infection for the development of more effective vaccine strategies against lentiviral infections in general, including HIV-1.

Kinetics of neutralization of Po-218

International Nuclear Information System (INIS)

Chu, K.D.

1987-01-01

In a well-defined experimental system the neutralization of polonium-218 ions was investigated as a function of the physical and chemical properties of the controlled composition atmosphere. The mobilities of Po + and PoO 2 + are determined by combining experimental results with a computer model of the system. Three neutralization mechanisms were individually studied. The small ion recombination rate has been found to be proportional to the square root of radon concentration. The electron scavenging mechanism is responsible for the neutralization of Po + in NO 2 or H 2 O in nitrogen. When PoO 2 + is formed, the electron transfer mechanism dominates the neutralization process. The electron is transferred to PoO 2 + from molecules with lower ionization potentials. The ionization potential of PoO 2 + is also determined to be 10.44 +/- 0.05 eV

Neutral and Non-Neutral Evolution of Duplicated Genes with Gene Conversion

Directory of Open Access Journals (Sweden)

Jeffrey A. Fawcett

2011-02-01

Full Text Available Gene conversion is one of the major mutational mechanisms involved in the DNA sequence evolution of duplicated genes. It contributes to create unique patters of DNA polymorphism within species and divergence between species. A typical pattern is so-called concerted evolution, in which the divergence between duplicates is maintained low for a long time because of frequent exchanges of DNA fragments. In addition, gene conversion affects the DNA evolution of duplicates in various ways especially when selection operates. Here, we review theoretical models to understand the evolution of duplicates in both neutral and non-neutral cases. We also explain how these theories contribute to interpreting real polymorphism and divergence data by using some intriguing examples.

Neutral signature Walker-VSI metrics

International Nuclear Information System (INIS)

Coley, A; McNutt, D; Musoke, N; Brooks, D; Hervik, S

2014-01-01

We will construct explicit examples of four-dimensional neutral signature Walker (but not necessarily degenerate Kundt) spaces for which all of the polynomial scalar curvature invariants vanish. We then investigate the properties of some particular subclasses of Ricci flat spaces. We also briefly describe some four-dimensional neutral signature Einstein spaces for which all of the polynomial scalar curvature invariants are constant. (paper)

Fast Neutral Pressure Measurements in NSTX

International Nuclear Information System (INIS)

R. Raman; H.W. Kugel; T. Provost; R. Gernhardt; T.R. Jarboe; M.G. Bell

2002-01-01

Several fast neutral pressure gauges have been installed on NSTX [National Spherical Torus Experiment] to measure the vessel and divertor pressure during inductive and coaxial helicity injected (CHI) plasma operations. Modified, PDX [Poloidal Divertor Experiment]-type Penning gauges have been installed on the upper and lower divertors. Neutral pressure measurements during plasma operations from these and from two shielded fast Micro ion gauges at different toroidal locations on the vessel mid-plane are described. A new unshielded ion gauge, referred to as the In-vessel Neutral Pressure (INP) gauge is under development

Design of a neutral three-dimensional electro-Fenton system with foam nickel as particle electrodes for wastewater treatment

International Nuclear Information System (INIS)

Liu, Wei; Ai, Zhihui; Zhang, Lizhi

2012-01-01

Highlights: ► Remove RhB by a novel 3D-E-Fenton system using foam nickel as particle electrodes. ► The 3D-E-Fenton system exhibit much higher RhB removal efficiency than the counterpart 3D-E and E-Fenton system. ► Foam nickel as a particle electrode displays good oxygen reduction activity. ► The performance of RhB removal was optimized by some operating parameters and the optimization pH was the neutral. - Abstract: In this work, we demonstrate a novel three-dimensional electro-Fenton system (3D-E-Fenton) for wastewater treatment with foam nickel, activated carbon fiber and Ti/RuO 2 –IrO 2 as the particle electrodes, the cathode, and the anode respectively. This 3D-E-Fenton system could exhibit much higher rhodamine B removal efficiency (99%) than the counterpart three-dimensional electrochemical system (33%) and E-Fenton system (19%) at neutral pH in 30 min. The degradation efficiency enhancement was attributed to much more hydroxyl radicals generated in the 3D-E-Fenton system because foam nickel particle electrodes could activate molecular oxygen to produce ·O 2 − via a single-electron transfer pathway to subsequently generate more H 2 O 2 and hydroxyl radicals. This is the first observation of molecular oxygen activation over the particle electrodes in the three-dimensional electrochemical system. These interesting findings could provide some new insight on the development of high efficient E-Fenton system for wastewater treatment at neutral pH.

Edge momentum transport by neutrals: an interpretive numerical framework

Science.gov (United States)

Omotani, J. T.; Newton, S. L.; Pusztai, I.; Viezzer, E.; Fülöp, T.; The ASDEX Upgrade Team

2017-06-01

Due to their high cross-field mobility, neutrals can contribute to momentum transport even at the low relative densities found inside the separatrix and they can generate intrinsic rotation. We use a charge-exchange dominated solution to the neutral kinetic equation, coupled to neoclassical ions, to evaluate the momentum transport due to neutrals. Numerical solutions to the drift-kinetic equation allow us to cover the full range of collisionality, including the intermediate levels typical of the tokamak edge. In the edge there are several processes likely to contribute to momentum transport in addition to neutrals. Therefore, we present here an interpretive framework that can evaluate the momentum transport through neutrals based on radial plasma profiles. We demonstrate its application by analysing the neutral angular momentum flux for an L-mode discharge in the ASDEX Upgrade tokamak. The magnitudes of the angular momentum fluxes we find here due to neutrals of 0.6-2 \\text{N} \\text{m} are comparable to the net torque on the plasma from neutral beam injection, indicating the importance of neutrals for rotation in the edge.

Neutralization of wastewater from nitrite passivation

International Nuclear Information System (INIS)

Pawlowski, L.; Mientki, B.; Wasag, H.

1982-01-01

A method for neutralization of wastewater formed in nitrite passivation has been presented. The method consists of introducing urea into wastewater and acidifying it with sulphuric acid. Wastewater is neutralized with lime. After clarification, wastewater can be drained outside the plant

Effect of neutral atoms on tokamak edge plasmas

International Nuclear Information System (INIS)

Fueloep, T.; Catto, Peter J.; Helander, P.

2001-01-01

Neutral atoms can significantly influence the physics of tokamak edge plasmas, e.g., by affecting the radial electric field and plasma flow there, which may, in turn, be important for plasma confinement. Earlier work [Fueloep et al., Phys. Plasmas 5, 3969 (1998)], assuming short mean-free path neutrals and Pfirsch-Schlueter ions, has shown that the ion-neutral coupling through charge-exchange affects the neoclassical flow velocity significantly. However, the mean-free path of the neutrals is not always small in comparison with the radial scale length of densities and temperatures in the edge pedestal. It is therefore desirable to determine what happens in the limit when the neutral mean-free path is comparable with the scale length. In the present work a self-similar solution for the neutral distribution function allowing for strong temperature and density variation is used, following the analysis of Helander and Krasheninnikov [Phys. Plasmas 3, 226 (1995)]. The self-similar solution is possible if the ratio of the mean-free path to the temperature and density scale length is constant throughout the edge plasma. The resulting neutral distribution function is used to investigate the neutral effects on the ion flow and electrostatic potential as this ratio varies from much less than one to order unity

The value of Network Neutrality for the Internet of Tomorrow : Report of the Dynamic Coalition on Network Neutrality

OpenAIRE

Belli , Luca; De Filippi , Primavera

2013-01-01

The report explores some of the most crucial facets of Network Neutrality, underscoring its close relationship with the full enjoyment of end-users fundamental rights. The report also includes a proposal for a Model Framework on Network Neutrality that has been elaborated by the Dynamic Coalition through an open, inclusive and multi-stakeholder effort, in order to promote an efficient safeguard of the Net Neutrality principle in accordance with international human rights standards.

Recent DIII-D neutral beam calibration results

International Nuclear Information System (INIS)

Wight, J.; Hong, R.M.; Phillips, J.

1991-10-01

Injected DIII-D neutral beam power is estimated based on three principle quantities: the fraction of ion beam that is neutralized in the neutralizer gas cell, the beamline transmission efficiency, and the fraction of beam reionized in the drift duct. System changes in the past few years have included a new gradient grid voltage operating point, ion source arc regulation, routine deuterium operations and new neutralizer gas flow controllers. Additionally, beam diagnostics have been improved and better calibrated. To properly characterize the beams the principle quantities have been re-measured. Two diagnostics are primarily used to measure the quantities. The beamline waterflow calorimetry system measures the neutralization efficiency and the beamline transmission efficiency, and the target tile thermocouples measure the reionization loss. An additional diagnostic, the target tile pyrometer, confirmed the reionization loss measurement. Descriptions and results of these measurements will be presented. 4 refs., 5 figs., 2 tabs

Negative ion based neutral beams for plasma heating

International Nuclear Information System (INIS)

Prelec, K.

1978-01-01

Neutral beam systems based on negative ions have been considered because of a high expected power efficiency. Methods for the production, acceleration and neutralization of negative ions will be reviewed and possibilities for an application in neutral beam lines explored

Targets for high power neutral beams

International Nuclear Information System (INIS)

Kim, J.

1980-01-01

Stopping high-power, long-pulse beams is fast becoming an engineering challenge, particularly in neutral beam injectors for heating magnetically confined plasmas. A brief review of neutral beam target technology is presented along with heat transfer calculations for some selected target designs

Neutralizing antibodies against two HIV-1 strains in consecutively collected serum samples: cross neutralization and association to HIV-1 related disease

DEFF Research Database (Denmark)

Arendrup, M; Nielsen, C M; Hansen, J E

1992-01-01

97 sera collected during a 10-year period from 10 HIV-1 infected individuals were tested for neutralizing capacity against a virus isolate FICPH-22 obtained from a Danish AIDS patient, and the laboratory strain HTLV-IIIB. Three patterns of serum neutralizing activity were demonstrated: (a) patients...... developing high neutralizing activity against both HIV strains; (b) patients developing high neutralizing activity against the Danish virus isolate; and (c) patients developing only low titers of neutralizing antibodies (NA) against both HIV strains. The HTLV-IIIB strain was less sensitive to serum...... neutralization than the FICPH-22 isolate and the appearance of NA against HTLV-IIIB was typically lacking several years behind that against FICPH-22 indicating a broadening of the NA response over time. No difference in clinical outcome was observed comparing patients reaching high titers of NA and patients...

Improved numerical calculation of the generation of a neutral beam by charge transfer between chlorine ions/neutrals and a graphite surface

International Nuclear Information System (INIS)

Kubota, Tomohiro; Samukawa, Seiji; Watanabe, Naoki; Ohtsuka, Shingo; Iwasaki, Takuya; Ono, Kohei; Iriye, Yasuroh

2014-01-01

The charge transfer process between chlorine particles (ions or neutrals) and a graphite surface on collision was investigated by using a highly stable numerical simulator based on time-dependent density functional theory to understand the generation mechanism of a high-efficiency neutral beam developed by Samukawa et al (2001 Japan. J. Appl. Phys. 40 L779). A straightforward calculation was achieved by adopting a large enough unit cell. The dependence of the neutralization efficiency on the incident energy of the particle was investigated, and the trend of the experimental result was reproduced. It was also found that doping the electrons and holes into graphite could change the charge transfer process and neutralization probability. This result suggests that it is possible to develop a neutral beam source that has high neutralization efficiency for both positive and negative ions. (paper)

Molecular signatures of hemagglutinin stem-directed heterosubtypic human neutralizing antibodies against influenza A viruses.

Directory of Open Access Journals (Sweden)

Yuval Avnir

2014-05-01

Full Text Available Recent studies have shown high usage of the IGHV1-69 germline immunoglobulin gene for influenza hemagglutinin stem-directed broadly-neutralizing antibodies (HV1-69-sBnAbs. Here we show that a major structural solution for these HV1-69-sBnAbs is achieved through a critical triad comprising two CDR-H2 loop anchor residues (a hydrophobic residue at position 53 (Ile or Met and Phe54, and CDR-H3-Tyr at positions 98±1; together with distinctive V-segment CDR amino acid substitutions that occur in positions sparse in AID/polymerase-η recognition motifs. A semi-synthetic IGHV1-69 phage-display library screen designed to investigate AID/polη restrictions resulted in the isolation of HV1-69-sBnAbs that featured a distinctive Ile52Ser mutation in the CDR-H2 loop, a universal CDR-H3 Tyr at position 98 or 99, and required as little as two additional substitutions for heterosubtypic neutralizing activity. The functional importance of the Ile52Ser mutation was confirmed by mutagenesis and by BCR studies. Structural modeling suggests that substitution of a small amino acid at position 52 (or 52a facilitates the insertion of CDR-H2 Phe54 and CDR-H3-Tyr into adjacent pockets on the stem. These results support the concept that activation and expansion of a defined subset of IGHV1-69-encoded B cells to produce potent HV1-69-sBnAbs does not necessarily require a heavily diversified V-segment acquired through recycling/reentry into the germinal center; rather, the incorporation of distinctive amino acid substitutions by Phase 2 long-patch error-prone repair of AID-induced mutations or by random non-AID SHM events may be sufficient. We propose that these routes of B cell maturation should be further investigated and exploited as a pathway for HV1-69-sBnAb elicitation by vaccination.

Mechanical design criteria for continuously operating neutral beams

International Nuclear Information System (INIS)

Vosen, S.R.; Bender, D.J.; Fink, J.H.; Lee, J.D.

1977-01-01

A schematic of a neutral beam injector is shown. Neutral gas is injected into the ion source, where a discharge ionizes the gas. The ions are drawn from the source by an extractor grid and then accelerated to full energy by the accel grids. After acceleration the ions pass through the neutralizer cell. Once through the neutralizer cell, the beam consists of neutrals and ions. The ions traveling with the beam are space charge neutralized by background electrons. The grid which precedes the direct converter is negatively charged and acts to separate the electrons from the rest of the beam. As a result of the beam's uncompensated space charge the remaining ions spread out from the beam to be collected at the direct converter. This paper presents a generalized analysis which will be useful in determining effects of energy and particle fluxes on the long-term performance of the grids

Optimization and validation of a neutralizing antibody assay for HIV-1 in A3R5 cells.

Science.gov (United States)

Sarzotti-Kelsoe, Marcella; Daniell, Xiaoju; Todd, Christopher A; Bilska, Miroslawa; Martelli, Amanda; LaBranche, Celia; Perez, Lautaro G; Ochsenbauer, Christina; Kappes, John C; Rountree, Wes; Denny, Thomas N; Montefiori, David C

2014-07-01

A3R5 is a human CD4(+) lymphoblastoid cell line that was engineered to express CCR5 and is useful for the detection of weak neutralizing antibody responses against tier 2 strains of HIV-1. Here we describe the optimization and validation of the HIV-1 neutralizing antibody assay that utilizes A3R5 cells, performed in compliance with Good Clinical Laboratory Practice (GCLP) guidelines. The assay utilizes Renilla luciferase-expressing replication competent infectious molecular clones (IMC) encoding heterologous env genes from different HIV-1 clades. Key assay validation parameters tested included specificity, accuracy, precision, limit of detection and quantitation, specificity, linearity and range, and robustness. Plasma samples demonstrated higher non-specific activity than serum samples in the A3R5 assay. This assay can tolerate a wide range of virus input but is more sensitive to cell concentration. The higher sensitivity of the A3R5 assay in neutralization responses to tier 2 strains of HIV-1 makes it complementary to, but not a substitute for the TZM-bl assay. The validated A3R5 assay is employed as an endpoint immunogenicity test for vaccine-elicited neutralizing antibodies against tier 2 strains of HIV-1, and to identify correlates of protection in HIV-1 vaccine trials conducted globally. Copyright © 2014 Elsevier B.V. All rights reserved.

Sputtering of neutral and ionic indium clusters

International Nuclear Information System (INIS)

Ma, Z.; Coon, S.R.; Calaway, W.F.; Pellin, M.J.; Gruen, D.M.; Von Nagy-Felsobuki, E.I.

1993-01-01

Secondary neutral and secondary ion cluster yields were measured during the sputtering of a polycrystalline indium surface by normally incident ∼4 keV Ar + ions. In the secondary neutral mass spectra, indium clusters as large as In 32 were observed. In the secondary ion mass spectra, indium clusters up to In 18 + were recorded. Cluster yields obtained from both the neutral and ion channel exhibited a power law dependence on the number of constituent atoms, n, in the cluster, with the exponents measured to be -5.6 and -4. 1, respectively. An abundance drop was observed at n=8, 15, and 16 in both the neutral and ion yield distributions suggesting that the stability of the ion (either secondary ion or photoion) plays a significant role in the observed distributions. In addition, our experiments suggest that unimolecular decomposition of the neutral cluster may also plays an important role in the measured yield distributions

Inhibition of Neutral Red Photolysis with Different Antioxidants

Directory of Open Access Journals (Sweden)

Zlatan Rimpapa

2007-02-01

Full Text Available Neutral red is a dye the azine structure which has been used as an acido-base indicator and a dye in histochemistry. In 1960 Goldhaber introduced Neutral red into the medium of resorbing bone cultures to localize the osteoclast in the living cultures. Using time-lapse microcinematography in order to follow the osteoclasts, he reported excellent contrast could be obtained with Neutral red due to the avidity of osteoclasts for this dye. Unfortunately, however, the photodynamic effect resulting from subsequent exposure of these cultures to light precluded this approach, and again in 1963. it was observed that the death of the osteoclasts was probably due to a photodynamic effect related to the dye in the cell, the presence of oxygen and the frequent exposure of light by our time-lapse photography. VIS and UV irradiation induced photolysis of Neutral red, and from Neutral red cation produced with photons a Neutral red radical. This Neutral red radical can be inhibited with action of an antioxidant, such as melatonin, glutathione, ascorbic acid, E vitamin, etc. We developed an assay with Neutral redphotolysis which utilizes a VIS and UV irradiation technique for quantification the inhibition of photolysis with action of an antioxidant. In this method Neutral red acts double, as a free radical generator and as a photosensitizer.

Soviet exoatmospheric neutral particle beam research

International Nuclear Information System (INIS)

Leiss, J.E.; Abrams, R.H.; Ehlers, K.W.; Farrell, J.A.; Gillespie, G.H.; Jameson, R.A.; Keefe, D.; Parker, R.K.

1988-02-01

This technical assessment was performed by a panel of eight U.S. scientists and engineers who are familiar with Soviet research through their own research experience, their knowledge of the published scientific literature and conference proceedings, and personal contacts with Soviet scientists and other foreign colleagues. Most of the technical components of a neutral particle beam generating system including the ion source, the accelerator, the accelerator radio frequency power supply, the beam conditioning and aiming system, and the beam neutralizer system are addressed. It does not address a number of other areas important to an exoatmospheric neutral beam system

Two dimensional neutral transport analysis in tokamak plasma

International Nuclear Information System (INIS)

Shimizu, Katsuhiro; Azumi, Masafumi

1987-02-01

Neutral particle influences the particle and energy balance, and play an important role on sputtering impurity and the charge exchange loss of neutral beam injection. In order to study neutral particle behaviour including the effects of asymmetric source and divertor configuration, the two dimensional neutral transport code has been developed using the Monte-Carlo techniques. This code includes the calculation of the H α radiation intensity based on the collisional-radiation model. The particle confinement time of the joule heated plasma in JT-60 tokamak is evaluated by comparing the calculated H α radiation intensity with the experimental data. The effect of the equilibrium on the neutral density profile in high-β plasma is also investigated. (author)

Temporal behavior of neutral particle fluxes in TFTR [Tokamak Fusion Test Reactor] neutral beam injectors

International Nuclear Information System (INIS)

Kamperschroer, J.H.; Gammel, G.M.; Roquemore, A.L.

1989-09-01

Data from an E parallel B charge exchange neutral analyzer (CENA), which views down the axis of a neutral beamline through an aperture in the target chamber calorimeter of the TFTR neutral beam test facility, exhibit two curious effects. First, there is a turn-on transient lasting tens of milliseconds having a magnitude up to three times that of the steady-state level. Second, there is a 720 Hz, up to 20% peak-to-peak fluctuation persisting the entire pulse duration. The turn-on transient occurs as the neutralizer/ion source system reaches a new pressure equilibrium following the effective ion source gas throughput reduction by particle removal as ion beam. Widths of the transient are a function of the gas throughput into the ion source, decreasing as the gas supply rate is reduced. Heating of the neutalizer gas by the beam is assumed responsible, with gas temperature increasing as gas supply rate is decreased. At low gas supply rates, the transient is primarliy due to dynamic changes in the neutralizer line density and/or beam species composition. Light emission from the drift duct corroborate the CENA data. At high gas supply rates, dynamic changes in component divergence and/or spatial profiles of the source plasma are necessary to explain the observations. The 720 Hz fluctuation is attributed to a 3% peak-to-peak ripple of 720 Hz on the arc power supply amplified by the quadratic relationship between beam divergence and beam current. Tight collimation by CENA apertures cause it to accept a very small part of the ion source's velocity space, producing a signal linearly proportional to beam divergence. Estimated fluctuations in the peak power density delivered to the plasma under these conditions are a modest 3--8% peak to peak. The efffects of both phenomena on the injected neutral beam can be ameliorated by careful operion of the ion sources. 21 refs., 11 figs., 2 tabs

Charge-leveling and proper treatment of long-range electrostatics in all-atom molecular dynamics at constant pH.

Science.gov (United States)

Wallace, Jason A; Shen, Jana K

2012-11-14

Recent development of constant pH molecular dynamics (CpHMD) methods has offered promise for adding pH-stat in molecular dynamics simulations. However, until now the working pH molecular dynamics (pHMD) implementations are dependent in part or whole on implicit-solvent models. Here we show that proper treatment of long-range electrostatics and maintaining charge neutrality of the system are critical for extending the continuous pHMD framework to the all-atom representation. The former is achieved here by adding forces to titration coordinates due to long-range electrostatics based on the generalized reaction field method, while the latter is made possible by a charge-leveling technique that couples proton titration with simultaneous ionization or neutralization of a co-ion in solution. We test the new method using the pH-replica-exchange CpHMD simulations of a series of aliphatic dicarboxylic acids with varying carbon chain length. The average absolute deviation from the experimental pK(a) values is merely 0.18 units. The results show that accounting for the forces due to extended electrostatics removes the large random noise in propagating titration coordinates, while maintaining charge neutrality of the system improves the accuracy in the calculated electrostatic interaction between ionizable sites. Thus, we believe that the way is paved for realizing pH-controlled all-atom molecular dynamics in the near future.

Net Neutrality and Inflation of Traffic

NARCIS (Netherlands)

Peitz, M.; Schütt, F.

2015-01-01

Under strict net neutrality Internet service providers (ISPs) are required to carry data without any differentiation and at no cost to the content provider. We provide a simple framework with a monopoly ISP to evaluate different net neutrality rules. Content differs in its sensitivity to delay.

Global panel of HIV-1 Env reference strains for standardized assessments of vaccine-elicited neutralizing antibodies.

Science.gov (United States)

deCamp, Allan; Hraber, Peter; Bailer, Robert T; Seaman, Michael S; Ochsenbauer, Christina; Kappes, John; Gottardo, Raphael; Edlefsen, Paul; Self, Steve; Tang, Haili; Greene, Kelli; Gao, Hongmei; Daniell, Xiaoju; Sarzotti-Kelsoe, Marcella; Gorny, Miroslaw K; Zolla-Pazner, Susan; LaBranche, Celia C; Mascola, John R; Korber, Bette T; Montefiori, David C

2014-03-01

Standardized assessments of HIV-1 vaccine-elicited neutralizing antibody responses are complicated by the genetic and antigenic variability of the viral envelope glycoproteins (Envs). To address these issues, suitable reference strains are needed that are representative of the global epidemic. Several panels have been recommended previously, but no clear answers have been available on how many and which strains are best suited for this purpose. We used a statistical model selection method to identify a global panel of reference Env clones from among 219 Env-pseudotyped viruses assayed in TZM-bl cells with sera from 205 HIV-1-infected individuals. The Envs and sera were sampled globally from diverse geographic locations and represented all major genetic subtypes and circulating recombinant forms of the virus. Assays with a panel size of only nine viruses adequately represented the spectrum of HIV-1 serum neutralizing activity seen with the larger panel of 219 viruses. An optimal panel of nine viruses was selected and augmented with three additional viruses for greater genetic and antigenic coverage. The spectrum of HIV-1 serum neutralizing activity seen with the final 12-virus panel closely approximated the activity seen with subtype-matched viruses. Moreover, the final panel was highly sensitive for detection of many of the known broadly neutralizing antibodies. For broader assay applications, all 12 Env clones were converted to infectious molecular clones using a proviral backbone carrying a Renilla luciferase reporter gene (Env.IMC.LucR viruses). This global panel should facilitate highly standardized assessments of vaccine-elicited neutralizing antibodies across multiple HIV-1 vaccine platforms in different parts of the world. An effective HIV-1 vaccine will need to overcome the extraordinary genetic variability of the virus, where most variation occurs in the viral envelope glycoproteins that are the sole targets for neutralizing antibodies. Efforts to elicit

Mechanism of the Glycosidic Bond Cleavage of Mismatched Thymine in Human Thymine DNA Glycosylase Revealed by Classical Molecular Dynamics and Quantum Mechanical/Molecular Mechanical Calculations.

Science.gov (United States)

Kanaan, Natalia; Crehuet, Ramon; Imhof, Petra

2015-09-24

Base excision of mismatched or damaged nucleotides catalyzed by glycosylase enzymes is the first step of the base excision repair system, a machinery preserving the integrity of DNA. Thymine DNA glycosylase recognizes and removes mismatched thymine by cleaving the C1'-N1 bond between the base and the sugar ring. Our quantum mechanical/molecular mechanical calculations of this reaction in human thymine DNA glycosylase reveal a requirement for a positive charge in the active site to facilitate C1'-N1 bond scission: protonation of His151 significantly lowers the free energy barrier for C1'-N1 bond dissociation compared to the situation with neutral His151. Shuttling a proton from His151 to the thymine base further reduces the activation free energy for glycosidic bond cleavage. Classical molecular dynamics simulations of the H151A mutant suggest that the mutation to the smaller, neutral, residue increases the water accessibility of the thymine base, rendering direct proton transfer from the bulk feasible. Quantum mechanical/molecular mechanical calculations of the glycosidic bond cleavage reaction in the H151A mutant show that the activation free energy is slightly lower than in the wild-type enzyme, explaining the experimentally observed higher reaction rates in this mutant.

ITER Neutral Beam Injection System

International Nuclear Information System (INIS)

Ohara, Yoshihiro; Tanaka, Shigeru; Akiba, Masato

1991-03-01

A Japanese design proposal of the ITER Neutral Beam Injection System (NBS) which is consistent with the ITER common design requirements is described. The injection system is required to deliver a neutral deuterium beam of 75MW at 1.3MeV to the reactor plasma and utilized not only for plasma heating but also for current drive and current profile control. The injection system is composed of 9 modules, each of which is designed so as to inject a 1.3MeV, 10MW neutral beam. The most important point in the design is that the injection system is based on the utilization of a cesium-seeded volume negative ion source which can produce an intense negative ion beam with high current density at a low source operating pressure. The design value of the source is based on the experimental values achieved at JAERI. The utilization of the cesium-seeded volume source is essential to the design of an efficient and compact neutral beam injection system which satisfies the ITER common design requirements. The critical components to realize this design are the 1.3MeV, 17A electrostatic accelerator and the high voltage DC acceleration power supply, whose performances must be demonstrated prior to the construction of ITER NBI system. (author)

Net neutrality and inflation of traffic

NARCIS (Netherlands)

Peitz, M.; Schütt, Florian

Under strict net neutrality Internet service providers (ISPs) are required to carry data without any differentiation and at no cost to the content provider. We provide a simple framework with a monopoly ISP to evaluate the short-run effects of different net neutrality rules. Content differs in its

Theoretical Studies of Electron Interaction with Molecular Ions and Mutual Neutralization - HeH and BeH

International Nuclear Information System (INIS)

Larson, Asa

2012-01-01

Reactions driven through electronic resonant states of HeH and BeH are discussed. These reactions are dissociative recombination (DR), resonant vibrational excitations (VE) and resonant dissociative excitations (DE). Another process is mutual neutralization (MN). HeH: The electronic resonant states of HeH are calculated using the full Configuration Interaction (CI) method with a large basis set. To obtain the autoionization widths electron scattering calculations are carried out using the Complex-Kohn variational method. The target ion is then described with a multi- reference CI wave function. Non-adiabatic couplings between the resonant states are computed using a method developed by V. Sidis. Cross sections for VE and DE of HeH in different vibrational states are computed by solving a driven Schroedinger equation and including autoionization using a local model. The non-adiabatic couplings between the resonant states are neglected. The cross sections become large when the energy is high enough to capture into the resonant states. The computed cross section for DE with the ion in the ground vibrational state is in very good agreement with measurement. The MN reaction, He + + H - →He*+ H, will be studied using strictly diabatic states. Autoionization will be included using the local model and the cross section will be computed by numerically solving a Matrix-Riccati equation for the radial wave function. BeH: We have previously studied DR of BeH + including the capture into electronic resonant states. Electronic couplings between the neutral states were included using a quasidiabatization procedure. Using the multi-channel quantum defect theory, the non-adiabatic couplings to the Rydberg states are now also incorporated. The indirect process results in sharp oscillations in the cross section and it influences the low temperature thermal rate coefficient for the reaction. Resonant VE and DE of BeH + in different vibrational states are investigated. The cross

Gas utilization in the Tokamak Fusion Test Reactor neutral beam injectors

International Nuclear Information System (INIS)

Kamperschroer, J.H.; Gammel, G.M.; Kugel, H.W.; Grisham, L.R.; Stevenson, T.N.; von Halle, A.; Williams, M.D.; Jones, T.T.C.

1989-01-01

Measurements of gas utilization were performed using hydrogen and deuterium beams in the Tokamak Fusion Test Reactor (TFTR) neutral beam test beamline to study the feasibility of operating tritium beams with existing ion sources under conditions of minimal tritium consumption. (i) It was found that the fraction of gas molecules introduced into the TFTR long-pulse ion sources that are converted to extracted ions (i.e., the ion source gas efficiency) was higher than with previous short-pulse sources. Gas efficiencies were studied over the range 33%--55%, and its effect on neutralization of the extracted ions was studied. At the high end of the gas efficiency range, the neutral fraction of the beam fell below that predicted from room-temperature molecular gas flow (similar to observations at the Joint European Torus). (ii) Beam isotope change studies were performed. No extracted hydrogen ions were observed in the first deuterium beam following a working gas change from H 2 to D 2 . There was no arc conditioning or gas injection preceding the first beam extraction attempt. (iii) Experiments were also performed to determine the reliability of ion source operation during the long waiting periods between pulses that are anticipated during tritium operation. It was found that an ion source conditioned to 120 kV could produce a clean beam pulse after a waiting period of 14 h by preceding the beam extraction with several acceleration voltage/filament warm-up pulses. It can be concluded that the operation of up to six ion sources on tritium gas should be compatible with on-site inventory restrictions established for D--T, Q = 1 experiments on TFTR

Molecular basis for endotoxin neutralization by amphipathic peptides derived from the alpha-helical cationic core-region of NK-lysin.

Science.gov (United States)

Brandenburg, Klaus; Garidel, Patrick; Fukuoka, Satoshi; Howe, Jörg; Koch, Michel H J; Gutsmann, Thomas; Andrä, Jörg

2010-08-01

An analysis of the interaction of the NK-lysin derived peptide NK-2 and of analogs thereof with bacterial lipopolysaccharide (LPS, endotoxin) was performed to determine the most important biophysical parameters for an effective LPS neutralization. We used microcalorimetry, FTIR spectroscopy, Zeta potential measurements, and small-angle X-ray scattering to analyze the peptide:LPS binding enthalpy, the accessible LPS surface charge, the fluidity of the LPS hydrocarbon chains, their phase transition enthalpy change, the aggregate structure of LPS, and how these parameters are modulated by the peptides. We conclude that (i) a high peptide:LPS binding affinity, which is facilitated by electrostatic and hydrophobic interactions and which leads to a positive Zeta potential, (ii) the formation of peptide-enriched domains, which destabilize the lipid packing, demonstrated by a drastic decrease of phase transition enthalpy change of LPS, and (iii) the multilamellarization of the LPS aggregate structure are crucial for an effective endotoxin neutralization by cationic peptides.

Molecular structure investigation of neutral, dimer and anion forms of 3,4-pyridinedicarboxylic acid: a combined experimental and theoretical study.

Science.gov (United States)

Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

2015-01-25

In this study, the structural and vibrational analysis of 3,4-pyridinedicarboxylic acid (3,4-PDCA) are presented using experimental techniques as FT-IR, FT-Raman, NMR, UV and quantum chemical calculations. FT-IR and FT-Raman spectra of 3,4-pyridinedicarboxylic acid in the solid phase are recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1), respectively. The geometrical parameters and energies of all different and possible monomer, dimer, anion(-1) and anion(-2) conformers of 3,4-PDCA are obtained from Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) basis set. There are sixteen conformers (C1C16) for this molecule (neutral form). The most stable conformer of 3,4-PDCA is the C1 conformer. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with scaled quantum mechanics (SQM) method. (1)H and (13)C NMR spectra are recorded and the chemical shifts are calculated by using DFT/B3LYP methods with 6-311++G(d,p) basis set. The UV absorption spectrum of the studied compound is recorded in the range of 200-400 nm by dissolved in ethanol. The optimized geometric parameters were compared with experimental data via the X-ray results derived from complexes of this molecule. In addition these, molecular electrostatic potential (MEP), thermodynamic and electronic properties, HOMO-LUMO energies and Mulliken atomic charges, are performed. Copyright © 2014 Elsevier B.V. All rights reserved.

Neutral currents, supernovae neutrinos, and nucleosynthesis

International Nuclear Information System (INIS)

Haxton, W.C.

1988-01-01

The inelastic interactions of neutrinos during stellar collapse and neutron star cooling are discussed. The primary mechanism for dissipative neutrino reactions is nuclear excitation by neutral current scattering, a process not included in standard descriptions of supernovae. Charge-current and neutral current ''preheating'' of iron lying outside the shock front appears to be significant in the few milliseconds near shock breakout. This could help produce a more energetic shock. During the cooling phase, the neutral current interactions of muon and taon neutrinos appear to be responsible for some interesting nucleosynthesis. I discuss two examples the production of fluorine and neutrino-induced r-process nucleosynthesis. 26 refs., 1 fig., 3 tabs

Impact of neutral density fluctuations on gas puff imaging diagnostics

Science.gov (United States)

Wersal, C.; Ricci, P.

2017-11-01

A three-dimensional turbulence simulation of the SOL and edge regions of a toroidally limited tokamak is carried out. The simulation couples self-consistently the drift-reduced two-fluid Braginskii equations to a kinetic equation for neutral atoms. A diagnostic neutral gas puff on the low-field side midplane is included and the impact of neutral density fluctuations on D_α light emission investigated. We find that neutral density fluctuations affect the D_α emission. In particular, at a radial distance from the gas puff smaller than the neutral mean free path, neutral density fluctuations are anti-correlated with plasma density, electron temperature, and D_α fluctuations. It follows that the neutral fluctuations reduce the D_α emission in most of the observed region and, therefore, have to be taken into account when interpreting the amplitude of the D_α emission. On the other hand, higher order statistical moments (skewness, kurtosis) and turbulence characteristics (such as correlation length, or the autocorrelation time) are not significantly affected by the neutral fluctuations. At distances from the gas puff larger than the neutral mean free path, a non-local shadowing effect influences the neutral density fluctuations. There, the D_α fluctuations are correlated with the neutral density fluctuations, and the high-order statistical moments and measurements of other turbulence properties are strongly affected by the neutral density fluctuations.

32 CFR 644.323 - Neutral language.

Science.gov (United States)

2010-07-01

... 32 National Defense 4 2010-07-01 2010-07-01 true Neutral language. 644.323 Section 644.323 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Disposal § 644.323 Neutral language. Wherever the words “man”, “men”, or their related...

Toxicity of binary chemical munition destruction products: methylphosphonic acid, methylphosphinic acid, 2-diisopropylaminoethanol, DF neutralent, and QL neutralent.

Science.gov (United States)

Watson, Rebecca E; Hafez, Ahmed M; Kremsky, Jonathan N; Bizzigotti, George O

2007-01-01

This paper reports the toxicity and environmental impact of neutralents produced from the hydrolysis of binary chemical agent precursor chemicals DF (methylphosphonic difluoride) and QL (2-[bis(1-methylethyl)amino]ethyl ethyl methylphosphonite). Following a literature review of the neutralent mixtures and constituents, basic toxicity tests were conducted to fill data gaps, including acute oral and dermal median lethal dose assays, the Ames mutagenicity test, and ecotoxicity tests. For methylphosphonic acid (MPA), a major constituent of DF neutralent, the acute oral LD(50) in the Sprague-Dawley rat was measured at 1888 mg/kg, and the Ames test using typical tester strains of Salmonella typhimurium and Escherichia coli was negative. The 48-h LC(50) values for pH-adjusted DF neutralent with Daphnia magna and Cyprinodon variegatus were > 2500 mg/L and 1593 mg/L, respectively. The acute oral LD(50) values in the rat for QL neutralent constituents methylphosphinic acid (MP) and 2-diisopropylaminoethanol (KB) were both determined to be 940 mg/kg, and the Ames test was negative for both. Good Laboratory Practice (GLP)-compliant ecotoxicity tests for MP and KB gave 48-h D. magna EC(50) values of 6.8 mg/L and 83 mg/L, respectively. GLP-compliant 96-h C. variegatus assays on MP and KB gave LC(50) values of 73 and 252 mg/L, respectively, and NOEC values of 22 and 108 mg/L. QL neutralent LD(50) values for acute oral and dermal toxicity tests were both > 5000 mg/kg, and the 48-h LD(50) values for D. magna and C. variegatus were 249 and 2500 mg/L, respectively. Using these data, the overall toxicity of the neutralents was assessed.

Fine- and hyperfine-structure effects in molecular photoionization. II. Resonance-enhanced multiphoton ionization and hyperfine-selective generation of molecular cations

Energy Technology Data Exchange (ETDEWEB)

Germann, Matthias; Willitsch, Stefan, E-mail: stefan.willitsch@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland)

2016-07-28

Resonance-enhanced multiphoton ionization (REMPI) is a widely used technique for studying molecular photoionization and producing molecular cations for spectroscopy and dynamics studies. Here, we present a model for describing hyperfine-structure effects in the REMPI process and for predicting hyperfine populations in molecular ions produced by this method. This model is a generalization of our model for fine- and hyperfine-structure effects in one-photon ionization of molecules presented in Paper I [M. Germann and S. Willitsch, J. Chem. Phys. 145, 044314 (2016)]. This generalization is achieved by covering two main aspects: (1) treatment of the neutral bound-bound transition including the hyperfine structure that makes up the first step of the REMPI process and (2) modification of our ionization model to account for anisotropic populations resulting from this first excitation step. Our findings may be used for analyzing results from experiments with molecular ions produced by REMPI and may serve as a theoretical background for hyperfine-selective ionization experiments.

Serbia's Military Neutrality: Origins, effects and challenges

Directory of Open Access Journals (Sweden)

Ejdus Filip

2014-10-01

Full Text Available Serbia is the only state in the Western Balkans that is not seeking NATO membership. In December 2007, Serbia declared military neutrality and in spite of its EU membership aspirations, developed very close relations with Moscow. The objective of this paper is threefold. First, I argue that in order to understand why Serbia declared military neutrality, one has to look both at the discursive terrain and domestic power struggles. The key narrative that was strategically used by mnemonic entrepreneurs, most importantly by the former Prime Minister Vojislav Koštunica, to legitimize military neutrality was the trauma of NATO intervention in 1999 and the ensuing secession of Kosovo. In the second part of the paper, I discuss the operational consequences of the military neutrality policy for Serbia's relations with NATO and Russia, as well as for military reform and EU accession. Finally, I spell out the challenges ahead in Serbia's neutrality policy and argue that its decision makers will increasingly be caught between pragmatic foreign policy requirements on the one hand and deeply entrenched traumatic memories on the other.

Modeling neutralization kinetics of HIV by broadly neutralizing monoclonal antibodies in genital secretions coating the cervicovaginal mucosa.

Directory of Open Access Journals (Sweden)

Scott A McKinley

Full Text Available Eliciting broadly neutralizing antibodies (bnAb in cervicovaginal mucus (CVM represents a promising "first line of defense" strategy to reduce vaginal HIV transmission. However, it remains unclear what levels of bnAb must be present in CVM to effectively reduce infection. We approached this complex question by modeling the dynamic tally of bnAb coverage on HIV. This analysis introduces a critical, timescale-dependent competition: to protect, bnAb must accumulate at sufficient stoichiometry to neutralize HIV faster than virions penetrate CVM and reach target cells. We developed a model that incorporates concentrations and diffusivities of HIV and bnAb in semen and CVM, kinetic rates for binding (kon and unbinding (koff of select bnAb, and physiologically relevant thicknesses of CVM and semen layers. Comprehensive model simulations lead to robust conclusions about neutralization kinetics in CVM. First, due to the limited time virions in semen need to penetrate CVM, substantially greater bnAb concentrations than in vitro estimates must be present in CVM to neutralize HIV. Second, the model predicts that bnAb with more rapid kon, almost independent of koff, should offer greater neutralization potency in vivo. These findings suggest the fastest arriving virions at target cells present the greatest likelihood of infection. It also implies the marked improvements in in vitro neutralization potency of many recently discovered bnAb may not translate to comparable reduction in the bnAb dose needed to confer protection against initial vaginal infections. Our modeling framework offers a valuable tool to gaining quantitative insights into the dynamics of mucosal immunity against HIV and other infectious diseases.

Modeling neutralization kinetics of HIV by broadly neutralizing monoclonal antibodies in genital secretions coating the cervicovaginal mucosa.

Science.gov (United States)

McKinley, Scott A; Chen, Alex; Shi, Feng; Wang, Simi; Mucha, Peter J; Forest, M Gregory; Lai, Samuel K

2014-01-01

Eliciting broadly neutralizing antibodies (bnAb) in cervicovaginal mucus (CVM) represents a promising "first line of defense" strategy to reduce vaginal HIV transmission. However, it remains unclear what levels of bnAb must be present in CVM to effectively reduce infection. We approached this complex question by modeling the dynamic tally of bnAb coverage on HIV. This analysis introduces a critical, timescale-dependent competition: to protect, bnAb must accumulate at sufficient stoichiometry to neutralize HIV faster than virions penetrate CVM and reach target cells. We developed a model that incorporates concentrations and diffusivities of HIV and bnAb in semen and CVM, kinetic rates for binding (kon) and unbinding (koff) of select bnAb, and physiologically relevant thicknesses of CVM and semen layers. Comprehensive model simulations lead to robust conclusions about neutralization kinetics in CVM. First, due to the limited time virions in semen need to penetrate CVM, substantially greater bnAb concentrations than in vitro estimates must be present in CVM to neutralize HIV. Second, the model predicts that bnAb with more rapid kon, almost independent of koff, should offer greater neutralization potency in vivo. These findings suggest the fastest arriving virions at target cells present the greatest likelihood of infection. It also implies the marked improvements in in vitro neutralization potency of many recently discovered bnAb may not translate to comparable reduction in the bnAb dose needed to confer protection against initial vaginal infections. Our modeling framework offers a valuable tool to gaining quantitative insights into the dynamics of mucosal immunity against HIV and other infectious diseases.

Total aerobic destruction of azo contaminants with nanoscale zero-valent copper at neutral pH: promotion effect of in-situ generated carbon center radicals.

Science.gov (United States)

Dong, Guohui; Ai, Zhihui; Zhang, Lizhi

2014-12-01

In this study, nanoscale zero-valent copper (nZVC) was synthesized with a facile solvothermal method and used for the aerobic removal of azo contaminants at neutral pH for the first time. We found that both Cu(I) and OH generated during the nZVC induced molecular oxygen activation process accounted for the rapid total destruction of azo contaminants in the nZVC/Air system, where nZVC could activate molecular oxygen to produce H2O2, and also release Cu(I) to break the -NN- bond of azo contaminants via the sandmeyer reaction for the generation of carbon center radicals. The in-situ generated carbon center radicals would then react with OH produced by the Cu(I) catalyzed decomposition of H2O2, resulting in the generation of low molecular weight organic acids and their subsequent mineralization. The indispensible role of Cu(I) catalyzed sandmeyer reaction and the promotion effect of in-situ generated carbon center radicals on the rapid total destruction of azo contaminants in the nZVC/Air system were confirmed by gas chromatography-mass spectrometry analysis. This study can deepen our understanding on the degradation of organic pollutant with molecular oxygen activated by zero valent metal, and also provide a new method to remove azo contaminants at neutral pH. Copyright © 2014 Elsevier Ltd. All rights reserved.

A charge-driven molecular water pump.

Science.gov (United States)

Gong, Xiaojing; Li, Jingyuan; Lu, Hangjun; Wan, Rongzheng; Li, Jichen; Hu, Jun; Fang, Haiping

2007-11-01

Understanding and controlling the transport of water across nanochannels is of great importance for designing novel molecular devices, machines and sensors and has wide applications, including the desalination of seawater. Nanopumps driven by electric or magnetic fields can transport ions and magnetic quanta, but water is charge-neutral and has no magnetic moment. On the basis of molecular dynamics simulations, we propose a design for a molecular water pump. The design uses a combination of charges positioned adjacent to a nanopore and is inspired by the structure of channels in the cellular membrane that conduct water in and out of the cell (aquaporins). The remarkable pumping ability is attributed to the charge dipole-induced ordering of water confined in the nanochannels, where water can be easily driven by external fields in a concerted fashion. These findings may provide possibilities for developing water transport devices that function without osmotic pressure or a hydrostatic pressure gradient.

Assessing Date Palm Genetic Diversity Using Different Molecular Markers.

Science.gov (United States)

Atia, Mohamed A M; Sakr, Mahmoud M; Adawy, Sami S

2017-01-01

Molecular marker technologies which rely on DNA analysis provide powerful tools to assess biodiversity at different levels, i.e., among and within species. A range of different molecular marker techniques have been developed and extensively applied for detecting variability in date palm at the DNA level. Recently, the employment of gene-targeting molecular marker approaches to study biodiversity and genetic variations in many plant species has increased the attention of researchers interested in date palm to carry out phylogenetic studies using these novel marker systems. Molecular markers are good indicators of genetic distances among accessions, because DNA-based markers are neutral in the face of selection. Here we describe the employment of multidisciplinary molecular marker approaches: amplified fragment length polymorphism (AFLP), start codon targeted (SCoT) polymorphism, conserved DNA-derived polymorphism (CDDP), intron-targeted amplified polymorphism (ITAP), simple sequence repeats (SSR), and random amplified polymorphic DNA (RAPD) to assess genetic diversity in date palm.

Corrosion protection method by neutral treatment for boilers

International Nuclear Information System (INIS)

Ishikawa, Hisashige

1978-01-01

The corrosion protection method by neutral treatment has been applied in Europe mainly for boilers and nuclear reactors instead of existing all volatile treatment. The cause of corrosion of steel and copper in water and the effect of neutral treatment, that is the effect of protection film of magnetite in steel and cuprous oxide in copper alloy, are explained with the characteristic figure of PH, electromotive force and chemical formula. The experience of applying this neutral treatment to the Wedel thermal power plant and the system flow sheet, the water treatment equipment, relating instrumentations and the water examination are described in detail. Hydrogen peroxide is injected in this neutral treatment. The comparison between the existing water treatment and the neutral treatment and their merits and demerits are explained. (Nakai, Y.)

The Myth of Neutral Judge: Overcoming Neutrality by the Cognition Theory And the Pursuit of Legal Certainty

Directory of Open Access Journals (Sweden)

Alyane Almeida de Araújo

2016-11-01

Full Text Available The  Law  scientific-rational  character  created  the  image  of  a  neutral  judge;  however, Neuroscience currently shows that the decision-making process involves activations in the prefrontal cortex along with emotions management areas. The aim of this work is to check the subsistence of the neutral judge after the cognition theory, with points of reflexion in post- positivist hermeneutics. Using the comprehensive method on bibliographic prospection, we conclude that despite the neutrality has been overcome, the search for legal certainty continues, which will be achieved through values and social purposes of the onwn normative system.

Somatic populations of PGT135-137 HIV-1-neutralizing antibodies identified by 454 pyrosequencing and bioinformatics

Directory of Open Access Journals (Sweden)

Jiang eZhu

2012-09-01

Full Text Available Select HIV-1-infected individuals develop sera capable of neutralizing diverse viral strains. The molecular basis of this neutralization is currently being deciphered by the isolation of HIV-1-neutralizing antibodies. In one infected donor, three neutralizing antibodies, PGT135-137, were identified by assessment of neutralization from individually sorted B cells and found to recognize an epitope containing an N-linked glycan at residue 332 on HIV-1 gp120. Here we use deep sequencing and bioinformatics methods to interrogate the B cell record of this donor to gain a more complete understanding of the humoral immune response. PGT135-137-gene family-specific primers were used to amplify heavy and light chain-variable domain sequences. 454 pyrosequencing produced 141,298 heavy-chain sequences of IGHV4-39 origin and 87,229 light-chain sequences of IGKV3-15 origin. A number of heavy and light chain sequences of ~90% identity to PGT137, several to PGT136, and none of high identity to PGT135 were identified. After expansion of these sequences to include close phylogenetic relatives, a total of 202 heavy-chain sequences and 72 light-chain sequences were identified. These sequences were clustered into populations of 95% identity comprising 15 for heavy chain and 10 for light chain, and a select sequence from each population was synthesized and reconstituted with a PGT137-partner chain. Reconstituted antibodies showed varied neutralization phenotypes for HIV-1 clade A and D isolates. Sequence diversity of the antibody population represented by these tested sequences was notably higher than observed with a 454 pyrosequencing-control analysis on 10 antibodies of defined sequence, suggesting that this diversity results primarily from somatic maturation. Our results thus provide an example of how pathogens like HIV-1 are opposed by a varied humoral immune response, derived from intrinsic mechanisms of antibody development, and embodied by somatic populations

Neutral beam development plan

International Nuclear Information System (INIS)

Staten, H.S.

1980-08-01

The national plan is presented for developing advanced injection systems for use on upgrades of existing experiments, and use on future facilities such as ETF, to be built in the late 1980's or early 90's where power production from magnetic fusion will move closer to a reality. Not only must higher power and longer pulse length systems be developed , but they must operate reliably; they must be a tool for the experimenter, not the experiment itself. Neutral beam systems handle large amounts of energy and as such, they often are as complicated as the plasma physics experiment itself. This presents a significant challenge to the neutral beam developer

Photoproduction of neutral pions off protons

NARCIS (Netherlands)

Crede, V.; Sparks, N.; Wilson, A.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, R.; Bartholomy, O.; Bayadilov, D.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Funke, Chr; Gregor, R.; Gridnev, A.; Gutz, E.; Hillert, W.; Hoffmeister, P.; Jaegle, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Klein, Frank; Klein, Friedrich; Klempt, E.; Kotulla, M.; Krusche, B.; Löhner, H.; Lopatin, I. V.; Lugert, S.; Menze, D.; Mertens, T.; Messchendorp, J. G.; Metag, V.; Nanova, M.; Nikonov, V. A.; Novinski, D.; Novotny, R.; Ostrick, M.; Pant, L. M.; van Pee, H.; Pfeiffer, M.; Roy, A.; Sarantsev, A. V.; Schadmand, S.; Schmidt, C.; Schmieden, H.; Schoch, B.; Shende, S.; Sokhoyan, V.; Suele, A.; Sumachev, V. V.; Szczepanek, T.; Thoma, U.; Trnka, D.; Varma, R.; Walther, D.; Wendel, Ch

2011-01-01

Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction gamma p -> p pi(0) for photon energies between 0.85 and 2.50 GeV. The pi(0) mesons are observed in their dominant neutral decay mode: pi(0) -> gamma gamma. For the first time, the differential cross

Gender Neutrality: Women's Friend or Foe?

Science.gov (United States)

Steuernagel, Trudy

Gender neutral public policies are those that are either silent on the question of the existence of significant gender differences or incorporate a perspective which mandates that such differences be ignored. Prominent voices today contend that gender neutrality favors males and have held the male standard as the one for which women should aspire.…

A safe and reliable neutralization assay based on pseudovirus to measure neutralizing antibody titer against poliovirus.

Science.gov (United States)

Liu, Shaohua; Song, Dongmei; Bai, Han; Lu, Weiwei; Dai, Xinxian; Hao, Chunsheng; Zhang, Zhongyang; Guo, Huijie; Zhang, Yue; Li, Xiuling

2017-12-01

With the promotion of inactivated poliomyelitis vaccine (IPV) and live attenuated oral poliomyelitis vaccine (OPV), the global reported cases of poliomyelitis have reduced sharply from 0.35 million in 1988 to 74 in 2015. The Polio Eradication & Endgame Strategic Plan published by WHO in 2013 included the strategy of implementation of poliovirus safe handling and containment measures to minimize the risks of facility-associated reintroduction of virus into the polio-free community to prevent the re-import of poliovirus. Toward this strategy, we produced replication-incompetent pseudovirus of poliovirus type 1, 2, 3 attenuated strains by constructing poliovirus capsid expression vectors and poliovirus replicon then transfecting HEK293T cells and developed a pseudovirus-based neutralization assay (pNA) to determine neutralizing antibody titer which is more secure, time-saving and reliable than conventional neutralization assay (cNA). By using anti-poliovirus rat serum, we demonstrated excellent correlation between neutralizing antibody titers measured by cNA and pNA. It was concluded that pNA can be a potential alternative to replace cNA as a safe and time-saving system for titer determination after live poliovirus's safekeeping. © 2017 Wiley Periodicals, Inc.

ICAN: High power neutral beam generation

International Nuclear Information System (INIS)

Moustaizis, S.D.; Lalousis, P.; Perrakis, K.; Auvray, P.; Larour, J.; Ducret, J.E.; Balcou, P.

2015-01-01

During the last few years there is an increasing interest on the development of alternative high power new negative ion source for Tokamak applications. The proposed new neutral beam device presents a number of advantages with respect to: the density current, the acceleration voltage, the relative compact dimension of the negative ion source, and the coupling of a high power laser beam for photo-neutralization of the negative ion beam. Here we numerically investigate, using a multi- fluid 1-D code, the acceleration and the extraction of high power ion beam from a Magnetically Insulated Diode (MID). The diode configuration will be coupled to a high power device capable of extracting a current up to a few kA with an accelerating voltage up to MeV. An efficiency of up to 92% of the coupling of the laser beam, is required in order to obtain a high power, up to GW, neutral beam. The new high energy, high average power, high efficiency (up to 30%) ICAN fiber laser is proposed for both the plasma generation and the photo-neutralizer configuration. (authors)

Are Moral Disengagement, Neutralization Techniques, and Self-Serving Cognitive Distortions the Same? Developing a Unified Scale of Moral Neutralization of Aggression

Directory of Open Access Journals (Sweden)

Denis Ribeaud

2010-12-01

Full Text Available

Quantum chemical study of the interaction of elemental Hg with small neutral, anionic and cationic Aun (n = 1–6) clusters

International Nuclear Information System (INIS)

Siddiqui, Shamoon Ahmad; Bouarissa, Nadir; Rasheed, Tabish; Al-Assiri, M.S.

2013-01-01

Graphical abstract: Binding energies as a function of cluster size for Au n Hg, Au n Hg + and Au n Hg − complexes. Highlights: ► Hg adsorption of neutral and charged Au n (n = 1–6) clusters has been discussed. ► Size and charged state of cluster significantly affect the Hg adsorption. ► Transfer of electron mainly found from s orbital of Hg to s orbital of Au. - Abstract: Adsorption of elemental mercury (Hg) on small neutral, cationic and anionic gold clusters (Au n , n = 1–6) has been studied by using the density functional theory (DFT). Results of this investigation show that frontier molecular orbital theory is a useful tool to predict the selectivity of Hg adsorption. It is found that adsorption of Hg on neutral, cationic and anionic Au n (n = 1–6) clusters are thermodynamically favorable. The binding energies of Hg on the cationic Au n clusters are greater than those on the neutral and anionic clusters. Natural bond orbital (NBO) analysis indicates that the flow of electrons in the neutral and charged clusters is mainly due to the s orbitals of Hg and Au. Results of NBO analysis also indicate that the binding energy of Hg with Au n clusters is directly proportional to the charge transfer, i.e. greater is the charge transfer, higher is the binding energy

Negative ion formation and neutralization processes, (2)

International Nuclear Information System (INIS)

Sugiura, Toshio

1982-09-01

This review is 2nd part of the report published at January 1982 (JAERI-M-9902). A compilation includes the survey of the data of the cross sections of H - and D - ion formations and the neutralization of these ions. This is also presented new information about the photosensitization by laser beam in dissociative-resonance electron capture of sulfur hexafluoride reported by Chen et al., for reference to enhancement of D - ions in discharge. For neutralization, the data of mutual neutralization and photodetachment are also presented. (author)

Dust in the Diffuse Neutral Interstellar Medium

Science.gov (United States)

Sofia, Ulysses J.

2008-05-01

Studies of interstellar dust have always relied heavily upon Laboratory Astrophysics for interpretation. Laboratory values, in the broad sense that includes theory, are needed for the most basic act of measuring interstellar abundances, to the more complex determination of what grains are responsible for particular extinction. The symbiotic relationship between astronomical observations and Laboratory Astrophysics has prompted both fields to move forward, especially in the era of high-resolution ultraviolet spectroscopy when new elemental species could be interpreted and observations were able to show the limits of laboratory determinations. Thanks to this synergy, we currently have a good idea of the quantity of the most abundant elements incorporated into dust in diffuse neutral interstellar clouds: carbon, oxygen, iron, silicon and magnesium. Now the task is to figure out how, chemically and physically, those elements are integrated into interstellar grains. We can do this by comparing extinction curves to grain populations in radiative transfer models. The limitation at the present time is the availability of optical constants in the infrared through ultraviolet for species that are likely to exist in dust, i.e., those that are easy to form in the physical environments around stars and in molecular clouds. Extinction in some lines of sight can be fit within current abundance limits and with the optical constants that are available. However the inability to reproduce other extinction curves suggests that optical constants can be improved, either in quality for compounds that have been measured, or quantity in the sense of providing data for more materials. This talk will address the current state and the future of dust studies in the diffuse neutral interstellar medium. This work is supported by the grant HST-AR-10979.01-A from the Space Telescope Science Institute to Whitman College.

Atomic and molecular physics of controlled thermonuclear fusion

International Nuclear Information System (INIS)

Joachain, C.J.; Post, D.E.

1983-01-01

This book attempts to provide a comprehensive introduction to the atomic and molecular physics of controlled thermonuclear fusion, and also a self-contained source from which to start a systematic study of the field. Presents an overview of fusion energy research, general principles of magnetic confinement, and general principles of inertial confinement. Discusses the calculation and measurement of atomic and molecular processes relevant to fusion, and the atomic and molecular physics of controlled thermonuclear research devices. Topics include recent progress in theoretical methods for atomic collisions; current theoretical techniques for electron-atom and electronion scattering; experimental aspects of electron impact ionization and excitation of positive ions; the theory of charge exchange and ionization by heavy particles; experiments on electron capture and ionization by multiply charged ions; Rydberg states; atomic and molecular processes in high temperature, low-density magnetically confined plasmas; atomic processes in high-density plasmas; the plasma boundary region and the role of atomic and molecular processes; neutral particle beam production and injection; spectroscopic plasma diagnostics; and particle diagnostics for magnetic fusion experiments

The neural fate of neutral information in emotion-enhanced memory.

Science.gov (United States)

Watts, Sarah; Buratto, Luciano G; Brotherhood, Emilie V; Barnacle, Gemma E; Schaefer, Alexandre

2014-07-01

In this study, we report evidence that neural activity reflecting the encoding of emotionally neutral information in memory is reduced when neutral and emotional stimuli are intermixed during encoding. Specifically, participants studied emotional and neutral pictures organized in mixed lists (in which emotional and neutral pictures were intermixed) or in pure lists (only-neutral or only-emotional pictures) and performed a recall test. To estimate encoding efficiency, we used the Dm effect, measured with event-related potentials. Recall for neutral items was lower in mixed compared to pure lists and posterior Dm activity for neutral items was reduced in mixed lists, whereas it remained robust in pure lists. These findings might be caused by an asymmetrical competition for attentional and working memory resources between emotional and neutral information, which could be a major determinant of emotional memory effects. Copyright © 2014 Society for Psychophysiological Research.

Neutral axis as damage sensitive feature

International Nuclear Information System (INIS)

Sigurdardottir, D H; Glisic, B

2013-01-01

Structural health monitoring (SHM) is the process of continuously or periodically measuring structural parameters and the transformation of the collected data into information on real structural conditions. The centroid of stiffness is a universal parameter and its position in a cross-section can be evaluated for any load-carrying beam structure as the position of the neutral axis under conveniently chosen loads. Thus, a change in the position of the neutral axis within a cross-section can indicate a change in the position of the centroid of stiffness, i.e., unusual structural behaviors. This paper proposes a novel monitoring method based on deterministic and probabilistic determination of the position of the neutral axis under conveniently chosen conditions. Therefore, the method proposed in this paper is potentially applicable to a large variety of beam-like structures. Data from two existing structures were used to validate the method and assess its performance: Streicker Bridge at Princeton University and the US202/NJ23 highway overpass in Wayne, NJ. The results show that the neutral axis location is varying even when damage is not present. Reasons for this variation are determined and the accuracy in the evaluation assessed. This paper concludes that the position of the neutral axis can be evaluated with sufficient accuracy using static and dynamic strain measurements performed on appropriate time-scales and indicates its potential to be used as a damage sensitive feature. (paper)

Neutral axis as damage sensitive feature

Science.gov (United States)

Sigurdardottir, D. H.; Glisic, B.

2013-07-01

Structural health monitoring (SHM) is the process of continuously or periodically measuring structural parameters and the transformation of the collected data into information on real structural conditions. The centroid of stiffness is a universal parameter and its position in a cross-section can be evaluated for any load-carrying beam structure as the position of the neutral axis under conveniently chosen loads. Thus, a change in the position of the neutral axis within a cross-section can indicate a change in the position of the centroid of stiffness, i.e., unusual structural behaviors. This paper proposes a novel monitoring method based on deterministic and probabilistic determination of the position of the neutral axis under conveniently chosen conditions. Therefore, the method proposed in this paper is potentially applicable to a large variety of beam-like structures. Data from two existing structures were used to validate the method and assess its performance: Streicker Bridge at Princeton University and the US202/NJ23 highway overpass in Wayne, NJ. The results show that the neutral axis location is varying even when damage is not present. Reasons for this variation are determined and the accuracy in the evaluation assessed. This paper concludes that the position of the neutral axis can be evaluated with sufficient accuracy using static and dynamic strain measurements performed on appropriate time-scales and indicates its potential to be used as a damage sensitive feature.

Evolutionary advantage via common action of recombination and neutrality

Science.gov (United States)

Saakian, David B.; Hu, Chin-Kun

2013-11-01

We investigate evolution models with recombination and neutrality. We consider the Crow-Kimura (parallel) mutation-selection model with the neutral fitness landscape, in which there is a central peak with high fitness A, and some of 1-point mutants have the same high fitness A, while the fitness of other sequences is 0. We find that the effect of recombination and neutrality depends on the concrete version of both neutrality and recombination. We consider three versions of neutrality: (a) all the nearest neighbor sequences of the peak sequence have the same high fitness A; (b) all the l-point mutations in a piece of genome of length l≥1 are neutral; (c) the neutral sequences are randomly distributed among the nearest neighbors of the peak sequences. We also consider three versions of recombination: (I) the simple horizontal gene transfer (HGT) of one nucleotide; (II) the exchange of a piece of genome of length l, HGT-l; (III) two-point crossover recombination (2CR). For the case of (a), the 2CR gives a rather strong contribution to the mean fitness, much stronger than that of HGT for a large genome length L. For the random distribution of neutral sequences there is a critical degree of neutrality νc, and for μmutations affect the mean-field-like and fluctuation-like factors similarly. Consequently, recombination can accelerate the non-mean-field (fluctuation) type dynamics without considerably affecting the mean-field-like factors.

Heavy-atom neutral beams for tandem-mirror end plugs

International Nuclear Information System (INIS)

Post, D.E.; Grisham, L.R.; Santarius, J.F.; Emmert, G.A.

1981-05-01

The advantages of neutral beams with Z greater than or equal to 3 formed from negative ions, accelerated to 0.5 to 1.0 MeV/amu, and neutralized with high efficiency, are investigated for use in tandem mirror reactor end plugs. These beams can produce Q's of 20 to 30, and thus can replace the currently proposed 200 to 500 keV neutral proton beams presently planned for tandem mirror reactors. Thus, these Z greater than or equal to 3 neutral beams increase the potential attractiveness of tandem mirror reactors by offering a substitute for difficult high energy neutral hydrogen end plug beams

Neutral beams for magnetic fusion

International Nuclear Information System (INIS)

Hooper, B.

1977-01-01

Significant advances in forming energetic beams of neutral hydrogen and deuterium atoms have led to a breakthrough in magnetic fusion: neutral beams are now heating plasmas to thermonuclear temperatures, here at LLL and at other laboratories. For example, in our 2XIIB experiment we have injected a 500-A-equivalent current of neutral deuterium atoms at an average energy of 18 keV, producing a dense plasma (10 14 particles/cm 3 ) at thermonuclear energy (14 keV or 160 million kelvins). Currently, LLL and LBL are developing beam energies in the 80- to 120-keV range for our upcoming MFTF experiment, for the TFTR tokamak experiment at Princeton, and for the Doublet III tokamak experiment at General Atomic. These results increase our long-range prospects of producing high-intensity beams of energies in the hundreds or even thousands of kilo-electron-volts, providing us with optimistic extrapolations for realizing power-producing fusion reactors

Charge neutralization of small ion beam clumps

Energy Technology Data Exchange (ETDEWEB)

Welch, D R [Mission Research Corp., Albuquerque, NM (United States); Olson, C L; Hanson, D L [Sandia National Labs., Albuquerque, NM (United States)

1997-12-31

The mega-ampere currents associated with light ion fusion (LIF) require excellent charge neutralization to prevent divergence growth. As the size and space-charge potential of a beam clump or `beamlet` become small (submillimeter size and kilovolt potentials), the neutralization becomes increasingly difficult. Linear theory predicts that plasma electrons cannot neutralize potentials < {phi}{sub crit} = (1/2)m{sub e}v{sub i}{sup 2}/e, where m{sub e} is the electron mass and v{sub i} is the ion beam velocity. A non-uniform beam would, therefore, have regions with potentials sufficient to add divergence to beam clumps. The neutralization of small beamlets produced on the SABLE accelerator and in numerical simulation has supported the theory, showing a plateau in divergence growths as the potential in the beamlet exceeds {phi}{sub crit}. (author). 1 tab., 2 figs., 4 refs.

Measurement of plasma production and neutralization in gas neutralizers

International Nuclear Information System (INIS)

Maor, D.; Meron, M.; Johnson, B.; Jones, K.; Agagu, A.; Hu, B.

1986-01-01

In order to satisfy the need of experimental data for the designing of gas neutralizers we have started a project aimed at measuring all relevant cross sections for the charge exchange of H - , H 0 and H + projectiles, as well as the cross sections for the production of ions in the target. The expected results of these latter measurements are shown schematically

Neutral Transport Simulations of Gas Puff Imaging Experiments on Alcator C-Mod

International Nuclear Information System (INIS)

Stotler, D.P.; LaBombard, B.; Terry, J.L.; Zweben, S.J.

2002-01-01

Visible imaging of gas puffs has been used on the Alcator C-Mod tokamak to characterize edge plasma turbulence, yielding data that can be compared with plasma turbulence codes. Simulations of these experiments with the DEGAS 2 Monte Carlo neutral transport code have been carried out to explore the relationship between the plasma fluctuations and the observed light emission. By imposing two-dimensional modulations on the measured time-average plasma density and temperature profiles, we demonstrate that the spatial structure of the emission cloud reflects that of the underlying turbulence. However, the photon emission rate depends on the plasma density and temperature in a complicated way, and no simple scheme for inferring the plasma parameters directly from the light emission patterns is apparent. The simulations indicate that excited atoms generated by molecular dissociation are a significant source of photons, further complicating interpretation of the gas puff imaging results.Visibl e imaging of gas puffs has been used on the Alcator C-Mod tokamak to characterize edge plasma turbulence, yielding data that can be compared with plasma turbulence codes. Simulations of these experiments with the DEGAS 2 Monte Carlo neutral transport code have been carried out to explore the relationship between the plasma fluctuations and the observed light emission. By imposing two-dimensional modulations on the measured time-average plasma density and temperature profiles, we demonstrate that the spatial structure of the emission cloud reflects that of the underlying turbulence. However, the photon emission rate depends on the plasma density and temperature in a complicated way, and no simple scheme for inferring the plasma parameters directly from the light emission patterns is apparent. The simulations indicate that excited atoms generated by molecular dissociation are a significant source of photons, further complicating interpretation of the gas puff imaging results

Evaluation of smallpox vaccines using variola neutralization.

Science.gov (United States)

Damon, Inger K; Davidson, Whitni B; Hughes, Christine M; Olson, Victoria A; Smith, Scott K; Holman, Robert C; Frey, Sharon E; Newman, Frances; Belshe, Robert B; Yan, Lihan; Karem, Kevin

2009-08-01

The search for a 'third'-generation smallpox vaccine has resulted in the development and characterization of several vaccine candidates. A significant barrier to acceptance is the absence of challenge models showing induction of correlates of protective immunity against variola virus. In this light, virus neutralization provides one of few experimental methods to show specific 'in vitro' activity of vaccines against variola virus. Here, we provide characterization of the ability of a modified vaccinia virus Ankara vaccine to induce variola virus-neutralizing antibodies, and we provide comparison with the neutralization elicited by standard Dryvax vaccination.

The innovation-enhancing effects of network neutrality

NARCIS (Netherlands)

Kocsis, V.; Weda, J.

2013-01-01

In the past decade, economists, legal experts, and policy makers have been discussing the effects of neutral network structures on - among others - innovations by content and application providers. Does network neutrality - the open and non-discriminatory functioning of the internet - provide

The Framing of Network Neutrality Governance

DEFF Research Database (Denmark)

Perry, James

The neutrality of the internet with regard to applications (e.g. search, social networking, email, to mention only three) has been central to innovation and growth in the knowledge-economy over the past two decades. Until recently, neutrality was built into the internet's design via its core stan...... with a critical analysis of their respective operational paradigms, the paper seeks to understand who is framing the debate, how they are doing so, and to what (systemic) effect....... generative: Useful innovations in applications of the internet could take hold easily, and it was difficult – or indeed impossible - for incumbent business interests to disrupt or sabotage them. However, this neutrality is now under threat. New technologies have given incumbent businesses the ability...

Current neutralization of converging ion beams

International Nuclear Information System (INIS)

Mosher, D.

1978-01-01

It is desired to consider the problem of current neutralization of heavy ion beams traversing gas backgrounds in which the conductivity changes due to beam heating and beam convergence. The procedure is to determine Green's-function solutions to the magnetic-diffusion equation derived from Maxwell's equations and an assumed scaler-plasma conductivity sigma for the background-electron current density j/sub e/. The present calculation is more general than some previously carried out in that arbitrary time variations for the beam current j/sub b/ and conductivity are allowed and the calculation is valid for both weak and strong neutralization. Results presented here must be combined with an appropriate energy-balance equation for the heated background in order to obtain the neutralization self-consistently

Truly neutral microobjects and oscillations in particle physics

International Nuclear Information System (INIS)

Bilenky, S.M.; Pontecorvo, B.

1982-01-01

Oscillation phenomena between different states of neutral elementary particles are discussed. The known kaon oscillation and the proposed neutrino, neutron and other kinds of oscillations are analysed. The proper bound states of neutral objects (neutrinos, neutrons, hydrogen atoms) are investigated in the case of small and strong violation of CP symmetry. Consequences concerning the observable masses and quantum numbers of such neutral objects are drawn. (D.Gy.)

Neutral currents in semileptonic reactions

International Nuclear Information System (INIS)

Paschos, E.A.

1975-05-01

The evidence for weak neutral currents is analyzed in semileptonic reactions with special emphasis on their Lorentz and internal symmetry structure. It is found that present observations are consistent with the expectations of gauge theories, but other possibilities can not be ruled out. Of particular interest in this respect is the presence of a large isoscalar component. The excitation of the Δ-resonance by neutral currents is analyzed, and pion-nucleon mass distributions are presented. Charge asymmetries sensitive to isoscalar-isovector interferences are discussed. (U.S.)

Long-Run Neutrality and Superneutrality in an ARIMA Framework.

OpenAIRE

Fisher, Mark E; Seater, John J

1993-01-01

The authors formalize long-run neutrality and long-run superneutrality in the context of a bivariate ARIMA model; show how the restrictions implied by long-run neutrality and long-run superneutrality depend on the orders of integration of the variables; apply their analysis to previous work, showing how that work is related to long-run neutrality and long-run superneutrality; and provide some new evidence on long-run neutrality and long-run superneutrality. Copyright 1993 by American Economic...

Research on Stress Neutral Layer Offset in the Straightening Process

Directory of Open Access Journals (Sweden)

Hailian Gui

2015-01-01

Full Text Available The stress neutral layer offset is analyzed by theoretical and numerical calculation methods. In traditional straightening theory, the stress neutral layer was consistent with the geometric central layer. However, there is a phenomenon that the stress neutral layer has some offset with the geometric neutral layer. This offset is a very important factor for improving the precision of the straightening force. The formula of the stress neutral layer offset is obtained by a theoretical method and the change law is given by numerical calculation method. The neutral layer offset theory provides the theoretical basis for establishing the model of straightening force precisely.

A General Nonlinear Fluid Model for Reacting Plasma-Neutral Mixtures

Energy Technology Data Exchange (ETDEWEB)

Meier, E T; Shumlak, U

2012-04-06

A generalized, computationally tractable fluid model for capturing the effects of neutral particles in plasmas is derived. The model derivation begins with Boltzmann equations for singly charged ions, electrons, and a single neutral species. Electron-impact ionization, radiative recombination, and resonant charge exchange reactions are included. Moments of the reaction collision terms are detailed. Moments of the Boltzmann equations for electron, ion, and neutral species are combined to yield a two-component plasma-neutral fluid model. Separate density, momentum, and energy equations, each including reaction transfer terms, are produced for the plasma and neutral equations. The required closures for the plasma-neutral model are discussed.

Auditors' Professional Skepticism: Neutrality versus Presumptive Doubt

NARCIS (Netherlands)

Groot, T.L.C.M.; Quadackers, L.M.; Wright, A.

2014-01-01

Although skepticism is widely viewed as essential to audit quality, there is a debate about what form is optimal. The two prevailing perspectives that have surfaced are "neutrality" and "presumptive doubt." With neutrality, auditors neither believe nor disbelieve client management. With presumptive

Neutral theory of chemical reaction networks

International Nuclear Information System (INIS)

Lee, Sang Hoon; Holme, Petter; Minnhagen, Petter; Bernhardsson, Sebastian; Kim, Beom Jun

2012-01-01

To what extent do the characteristic features of a chemical reaction network reflect its purpose and function? In general, one argues that correlations between specific features and specific functions are key to understanding a complex structure. However, specific features may sometimes be neutral and uncorrelated with any system-specific purpose, function or causal chain. Such neutral features are caused by chance and randomness. Here we compare two classes of chemical networks: one that has been subjected to biological evolution (the chemical reaction network of metabolism in living cells) and one that has not (the atmospheric planetary chemical reaction networks). Their degree distributions are shown to share the very same neutral system-independent features. The shape of the broad distributions is to a large extent controlled by a single parameter, the network size. From this perspective, there is little difference between atmospheric and metabolic networks; they are just different sizes of the same random assembling network. In other words, the shape of the degree distribution is a neutral characteristic feature and has no functional or evolutionary implications in itself; it is not a matter of life and death. (paper)

Acquired copy-neutral loss of heterozygosity of chromosome 1p as a molecular event associated with marrow fibrosis in MPL-mutated myeloproliferative neoplasms.

Science.gov (United States)

Rumi, Elisa; Pietra, Daniela; Guglielmelli, Paola; Bordoni, Roberta; Casetti, Ilaria; Milanesi, Chiara; Sant'Antonio, Emanuela; Ferretti, Virginia; Pancrazzi, Alessandro; Rotunno, Giada; Severgnini, Marco; Pietrelli, Alessandro; Astori, Cesare; Fugazza, Elena; Pascutto, Cristiana; Boveri, Emanuela; Passamonti, Francesco; De Bellis, Gianluca; Vannucchi, Alessandro; Cazzola, Mario

2013-05-23

We studied mutations of MPL exon 10 in patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF), first investigating a cohort of 892 consecutive patients. MPL mutation scanning was performed on granulocyte genomic DNA by using a high-resolution melt assay, and the mutant allele burden was evaluated by using deep sequencing. Somatic mutations of MPL, all but one involving codon W515, were detected in 26/661 (4%) patients with ET, 10/187 (5%) with PMF, and 7/44 (16%) patients with post-ET myelofibrosis. Comparison of JAK2 (V617F)-mutated and MPL-mutated patients showed only minor phenotypic differences. In an extended group of 62 MPL-mutated patients, the granulocyte mutant allele burden ranged from 1% to 95% and was significantly higher in patients with PMF or post-ET myelofibrosis compared with those with ET. Patients with higher mutation burdens had evidence of acquired copy-neutral loss of heterozygosity (CN-LOH) of chromosome 1p in granulocytes, consistent with a transition from heterozygosity to homozygosity for the MPL mutation in clonal cells. A significant association was found between MPL-mutant allele burden greater than 50% and marrow fibrosis. These observations suggest that acquired CN-LOH of chromosome 1p involving the MPL location may represent a molecular mechanism of fibrotic transformation in MPL-mutated myeloproliferative neoplasms.

Efficient Means of Detecting Neutral Atoms in Space

Science.gov (United States)

Zinicola, W. N.

2006-12-01

This summer, The Society of Physics Students granted me the opportunity to participate in an internship for The National Aeronautics and Space Administration (NASA) and The University of Maryland. Our chief interest was analyzing low energy neutral atoms that were created from random interactions of ions in space plasma. From detecting these neutrals one can project a image of what the plasma's composition is, and how this plasma changes through interactions with the solar wind. Presently, low energy neutral atom detectors have poor efficiency, typically in the range of 1%. Our goal was to increase this efficiency. To detect low energy neutrals we must first convert them from neutral molecules to negatively charged ions. Once converted, these "new" negatively charged ions can be easily detected and completely analyzed giving us information about their energy, mass, and instantaneous direction. The efficiency of the detector is drastically affected by the surface used for converting these neutrals. My job was first to create thin metal conversion surfaces. Then, using an X-ray photoelectron spectrometer, analyze atomic surface composition and gather work function values. Once the work function values were known we placed the surfaces in our neutral detector and measured their conversion efficiencies. Finally, a relation between the work function of the metal surface an its conversion efficiency was generated. With this relationship accurately measured one could use this information to help give suggestions on what surface would be the best to increase our detection efficiency. If we could increase the efficiency of these low energy neutral atom detectors by even 1% we would be able to decrease the size of the detector therefore making it cheaper and more applicable for space exploration.* * A special thanks to Dr. Michael Coplan of the University of Maryland for his support and guidance through all my research.

Detection of extensive cross-neutralization between pandemic and seasonal A/H1N1 Influenza Viruses using a pseudotype neutralization assay.

Directory of Open Access Journals (Sweden)

Béatrice Labrosse

Full Text Available BACKGROUND: Cross-immunity between seasonal and pandemic A/H1N1 influenza viruses remains uncertain. In particular, the extent that previous infection or vaccination by seasonal A/H1N1 viruses can elicit protective immunity against pandemic A/H1N1 is unclear. METHODOLOGY/PRINCIPAL FINDINGS: Neutralizing titers against seasonal A/H1N1 (A/Brisbane/59/2007 and against pandemic A/H1N1 (A/California/04/2009 were measured using an HIV-1-based pseudovirus neutralization assay. Using this highly sensitive assay, we found that a large fraction of subjects who had never been exposed to pandemic A/H1N1 express high levels of pandemic A/H1N1 neutralizing titers. A significant correlation was seen between neutralization of pandemic A/H1N1 and neutralization of a standard seasonal A/H1N1 strain. Significantly higher pandemic A/H1N1 neutralizing titers were measured in subjects who had received vaccination against seasonal influenza in 2008-2009. Higher pandemic neutralizing titers were also measured in subjects over 60 years of age. CONCLUSIONS/SIGNIFICANCE: Our findings reveal that the extent of protective cross-immunity between seasonal and pandemic A/H1N1 influenza viruses may be more important than previously estimated. This cross-immunity could provide a possible explanation of the relatively mild profile of the recent influenza pandemic.

46 CFR 120.376 - Grounded distribution systems (Neutral grounded).

Science.gov (United States)

2010-10-01

....376 Section 120.376 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150 PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS... distribution system having a neutral bus or conductor must have the neutral grounded. (c) The neutral or each...

Rare decays of neutral π and eta

International Nuclear Information System (INIS)

Poutissou, J.M.

1983-09-01

The decays of the pseudoscalar neutral mesons π degree and eta degree have provided a test of fundamental principles. The main branch, π degree → 2γ, was investigated in the late 60's in the context of current algebra and the decay rate calculated from the singular triangle diagram is in excellent agreement with experiment. Rare leptonic decays of the neutral pseudoscalar mesons are of interest because of the information they reveal about neutral currents or other exotic interactions between leptons and quarks. The author discusses recent information on the π degree → e + e - decay

46 CFR 183.376 - Grounded distribution systems (neutral grounded).

Science.gov (United States)

2010-10-01

....376 Section 183.376 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER... propulsion, power, lighting, or distribution system having a neutral bus or conductor must have the neutral... generator to ground before the generator is connected to the bus, except the neutral of an emergency power...

Analysis of variola and vaccinia virus neutralization assays for smallpox vaccines.

Science.gov (United States)

Hughes, Christine M; Newman, Frances K; Davidson, Whitni B; Olson, Victoria A; Smith, Scott K; Holman, Robert C; Yan, Lihan; Frey, Sharon E; Belshe, Robert B; Karem, Kevin L; Damon, Inger K

2012-07-01

Possible smallpox reemergence drives research for third-generation vaccines that effectively neutralize variola virus. A comparison of neutralization assays using different substrates, variola and vaccinia (Dryvax and modified vaccinia Ankara [MVA]), showed significantly different 90% neutralization titers; Dryvax underestimated while MVA overestimated variola neutralization. Third-generation vaccines may rely upon neutralization as a correlate of protection.

Atomic and molecular processes in JT-60U divertor plasmas

Energy Technology Data Exchange (ETDEWEB)

Takenaga, H.; Shimizu, K.; Itami, K. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment] [and others

1997-01-01

Atomic and molecular data are indispensable for the understanding of the divertor characteristics, because behavior of particles in the divertor plasma is closely related to the atomic and molecular processes. In the divertor configuration, heat and particles escaping from the main plasma flow onto the divertor plate along the magnetic field lines. In the divertor region, helium ash must be effectively exhausted, and radiation must be enhanced for the reduction of the heat load onto the divertor plate. In order to exhaust helium ash effectively, the difference between behavior of neutral hydrogen (including deuterium and tritium) and helium in the divertor plasma should be understood. Radiation from the divertor plasma generally caused by the impurities which produced by the erosion of the divertor plate and/or injected by gas-puffing. Therefore, it is important to understand impurity behavior in the divertor plasma. The ions hitting the divertor plate recycle through the processes of neutralization, reflection, absorption and desorption at the divertor plates and molecular dissociation, charge-exchange reaction and ionization in the divertor plasma. Behavior of hydrogen, helium and impurities in the divertor plasmas can not be understood without the atomic and molecular data. In this report, recent results of the divertor study related to the atomic and molecular processes in JT-60U were summarized. Behavior of neural deuterium and helium was discussed in section 2. In section 3, the comparisons between the modelling of the carbon impurity transport and the measurements of C II and C IV were discussed. In section 4, characteristics of the radiative divertor using Ne puffing were reported. The new diagnostic method for the electron density and temperature in the divertor plasmas using the intensity ratios of He I lines was described in section 5. (author)

Molecular electron affinities

International Nuclear Information System (INIS)

Fukuda, E.K.

1983-01-01

Molecular electron affinities have historically been difficult quantities to measure accurately. These difficulties arise from differences in structure between the ion and neutral as well as the existence of excited negative ion states. To circumvent these problems, relative electron affinities were determined in this dissertation by studying equilibrium electron transfer reactions using a pulsed ion cyclotron resonance (ICR) spectrometer. Direct measurement of ion and neutral concentrations for reactions of the general type, A - + B = B - + A, allow calculation of the equilibrium constant and, therefore, the free energy change. The free energy difference is related to the difference in electron affinities between A and B. A relative electron affinity scale covering a range of about 45 kcal/mol was constructed with various substituted p-benzoquinones, nitrobenzenes, anhydrides, and benzophenones. To assign absolute electron affinities, various species with accurately known electron affinities are tied to the scale via ion-cyclotron double resonance bracketing techniques. After the relative scale is anchored to these species with well-known electron affinities, the scale is then used as a check on other electron affinity values as well as generating new electron affinity values. Many discrepancies were found between the electron affinities measured using the ICR technique and previous literature determinations

Conversion of Syngas-Derived C2+ Mixed Oxygenates to C3-C5 Olefins over ZnxZryOz Mixed Oxides Catalysts

Energy Technology Data Exchange (ETDEWEB)

Smith, Colin D.; Lebarbier, Vanessa M.; Flake, Matthew D.; Ramasamy, Karthikeyan K.; Kovarik, Libor; Bowden, Mark E.; Onfroy, Thomas; Dagle, Robert A.

2016-04-01

In this study we report on a ZnxZryOz mixed oxide type catalyst capable of converting a syngas-derived C2+ mixed oxygenate feedstock to isobutene-rich olefins. Aqueous model feed comprising of ethanol, acetaldehyde, acetic acid, ethyl acetate, methanol, and propanol was used as representative liquid product derived from a Rh-based mixed oxygenate synthesis catalyst. Greater than 50% carbon yield to C3-C5 mixed olefins was demonstrated when operating at 400-450oC and 1 atm. In order to rationalize formation of the products observed feed components were individually evaluated. Major constituents of the feed mixture (ethanol, acetaldehyde, acetic acid, and ethyl acetate) were found to produce isobutene-rich olefins. C-C coupling was also demonstrated for propanol feedstock - a minor constituent of the mixed oxygenate feed - producing branched C6 olefins, revealing scalability to alcohols higher than ethanol following an analogous reaction pathway. Using ethanol and propanol feed mixtures, cross-coupling reactions produced mixtures of C4, C5, and C6 branched olefins. The presence of H2 in the feed was found to facilitate hydrogenation of the ketone intermediates, thus producing straight chain olefins as byproducts. While activity loss from coking is observed complete catalyst regeneration is achieved by employing mild oxidation. For conversion of the mixed oxygenate feed a Zr/Zn ratio of 2.5 and a reaction temperature of 450oC provides the best balance of stability, activity, and selectivity. X-ray diffraction and scanning transmission electron microscopy analysis reveals the presence of primarily cubic phase ZrO2 and a minor amount of the monoclinic phase, with ZnO being highly dispersed in the lattice. The presence of ZnO appears to stabilize the cubic phase resulting in less monoclinic phase as the ZnO concentration increases. Infrared spectroscopy shows the mixed oxide acid sites are characterized as primarily Lewis type acidity. The direct relationship between

Development of KSTAR Neutral Beam Heating System

Energy Technology Data Exchange (ETDEWEB)

Oh, B. H.; Song, W. S.; Yoon, B. J. (and others)

2007-10-15

The prototype components of a neutral beam injection (NBI) system have been developed for the KSTAR, and a capability of the manufactured components has been tested. High power ion source, acceleration power supply, other ion source power supplies, neutralizer, bending magnet for ion beam separation, calorimeter, and cryo-sorption pump have been developed by using the domestic technologies and tested for a neutral beam injection of 8 MW per beamline with a pulse duration of 300 seconds. The developed components have been continuously upgraded to achieve the design requirements. The development technology of high power and long pulse neutral beam injection system has been proved with the achievement of 5.2 MW output for a short pulse length and 1.6 MW output for a pulse length of 300 seconds. Using these development technologies, the domestic NB technology has been stabilized under the development of high power ion source, NB beamline components, high voltage and current power supplies, NB diagnostics, NB system operation and control.

International Thermonuclear Experimental Reactor (ITER) neutral beam design

International Nuclear Information System (INIS)

Myers, T.J.; Brook, J.W.; Spampinato, P.T.; Mueller, J.P.; Luzzi, T.E.; Sedgley, D.W.

1990-10-01

This report discusses the following topics on ITER neutral beam design: ion dump; neutralizer and module gas flow analysis; vacuum system; cryogenic system; maintainability; power distribution; and system cost

(IAM Series No 005) Are “Market Neutral” Hedge Funds Really Market Neutral?

OpenAIRE

Andrew Patton

2004-01-01

One can consider the concept of market neutrality for hedge funds as having breadth and depth: breadth reflects the number of market risks to which a fund is neutral, while depth reflects the completeness of the neutrality of the fund to market risks. We focus on market neutrality depth, and propose five different neutrality concepts. Mean neutrality nests the standard correlation-based definition of neutrality. Variance neutrality, Value-at-Risk neutrality and tail neutrality all relate to t...

Steady state neutral beam injector

International Nuclear Information System (INIS)

Mattoo, S.K.; Bandyopadhyay, M.; Baruah, U.K.; Bisai, N.; Chakbraborty, A.K.; Chakrapani, Ch.; Jana, M.R.; Bajpai, M.; Jaykumar, P.K.; Patel, D.; Patel, G.; Patel, P.J.; Prahlad, V.; Rao, N.V.M.; Rotti, C.; Singh, N.P.; Sridhar, B.

2000-01-01

Learning from operational reliability of neutral beam injectors in particular and various heating schemes including RF in general on TFTR, JET, JT-60, it has become clear that neutral beam injectors may find a greater role assigned to them for maintaining the plasma in steady state devices under construction. Many technological solutions, integrated in the present day generation of injectors have given rise to capability of producing multimegawatt power at many tens of kV. They have already operated for integrated time >10 5 S without deterioration in the performance. However, a new generation of injectors for steady state devices have to address to some basic issues. They stem from material erosion under particle bombardment, heat transfer > 10 MW/m 2 , frequent regeneration of cryopanels, inertial power supplies, data acquisition and control of large volume of data. Some of these engineering issues have been addressed to in the proposed neutral beam injector for SST-1 at our institute; the remaining shall have to wait for the inputs of the database generated from the actual experience with steady state injectors. (author)

Γ-source Neutral Point Clamped Inverter

DEFF Research Database (Denmark)

Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede

Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress...... and better output performance comparing with traditional two-level inverters. Integrating these two types of configurations can help neutral point inverters achieve enhanced votlage buck-boost capability....

Plasma heating with multi-MeV neutral atom beams

International Nuclear Information System (INIS)

Grisham, L.R.; Post, D.E.; Mikkelsen, D.R.; Eubank, H.P.

1981-10-01

We explore the utility and feasibility of neutral beams of greater than or equal to 6 AMU formed from negative ions, and also of D 0 formed from D - . The negative ions would be accelerated to approx. 1 to 2 MeV/AMU and neutralized, whereupon the neutral atoms would be used to heat and, perhaps, to drive current in magnetically confined plasmas. Such beams appear feasible and offer the promise of significant advantages relative to conventional neutral beams based on positive deuterium ions at approx. 150 keV

Net neutrality towards a co-regulatory solution

CERN Document Server

Marsden, Christopher T

2010-01-01

In considering market developments and policy responses to some of the most heated net-neutrality debates in Europe and the United States, Net Neutrality is the first, fully comprehensive overview of the subject. This book is also unique in providing readers with a supplementary outline of recommended policy prescriptives.

Energy spectrum of neutrals formed in an ion accelerator

International Nuclear Information System (INIS)

Fink, J.H.

1982-01-01

This work presents an estimate of the energy distribution of the neutrals formed in the ion beam accelerator. However it does not determine the fraction of those neutrals which leave the neutral beam injector and go on into the reactor. To do that, more details of the beam line performance are needed

Method to minimize the low-frequency neutral-point voltage oscillations with time-offset injection for neutral-point-clamped inverters

DEFF Research Database (Denmark)

Choi, Uimin; Lee, Kyo-Beum; Blaabjerg, Frede

2013-01-01

This paper proposes a method to reduce the low-frequency neutral-point voltage oscillations. The neutral-point voltage oscillations are considerably reduced by adding a time-offset to the three phase turn-on times. The proper time-offset is simply calculated considering the phase currents and dwell...

Coupled plasma-neutral transport model for the scrape-off region

International Nuclear Information System (INIS)

Galambos, J.D.; Peng, Y.K.M.; Heifetz, D.

1985-03-01

Analysis of the scrape-off region requires treatment of the plasma transport along and across the field lines and inclusion of the neutral transport effects. A method for modeling the scrape-off region that is presented here uses separate models for each of these aspects that are coupled together through an iteration procedure that requires only minimal numerical effort. The method is applied here to estimate the neutral pumping rates in the pump-limiter and divertor options for a proposed deuterium-tritium (D-T) ignition experiment. High neutral recycling in the vicinity of the neutralizer plate dramatically affects pumping rates for both the pump-limiter and divertor. In both cases, the plasma flow into the channel surrounding the neutralizer plate is greatly reduced by the neutral recycling. The fraction of this flow that is pumped can be large (> 50%), but in general it is dependent on the particular geometry and plasma conditions. It is estimated that pumping speeds approximately greater than 10 5 L/s are adequate for the exhaust requirements in the pump-limiter and the divertor cases. Also, high neutral recycling on the front surface of the limiter tends to increase the neutral pumping rate

Economic Features of the Internet and Network Neutrality

OpenAIRE

Nicholas Economides

2015-01-01

We discuss the issue of a possible abolition of network neutrality and the introduction of paid prioritization by residential broadband access networks.We show that, in short run analysis where bandwidth is fixed, and in the absence of congestion, network neutrality tends to maximize total surplus. When an ISP violates network neutrality and invests the extra profits to bandwidth expansion, the presence of more bandwidth alleviates the allocative distortion, and can even reverse it. We also d...

International bulletin on atomic and molecular data for fusion. No. 22

International Nuclear Information System (INIS)

Katsonis, K.

1983-05-01

This bulletin deals with atomic and molecular data for fusion. Work in progress is briefly reported (charge exchange of slow ionized ions with neutral gases, cross section for electron impact ionization of Alt). The bulletin contains a list of references covering the years 1981, 1982 and 1983 for publications on controlled thermonuclear fusion and plasma physics

Vendor neutral archive in PACS

International Nuclear Information System (INIS)

Agarwal, Tapesh Kumar; Sanjeev

2012-01-01

An archive is a location containing a collection of records, documents, or other materials of historical importance. An integral part of Picture Archiving and Communication System (PACS) is archiving. When a hospital needs to migrate a PACS vendor, the complete earlier data need to be migrated in the format of the newly procured PACS. It is both time and money consuming. To address this issue, the new concept of vendor neutral archive (VNA) has emerged. A VNA simply decouples the PACS and workstations at the archival layer. This is achieved by developing an application engine that receives, integrates, and transmits the data using the different syntax of a Digital Imaging and Communication in Medicine (DICOM) format. Transferring the data belonging to the old PACS to a new one is performed by a process called migration of data. In VNA, a number of different data migration techniques are available to facilitate transfer from the old PACS to the new one, the choice depending on the speed of migration and the importance of data. The techniques include simple DICOM migration, prefetch-based DICOM migration, medium migration, and the expensive non-DICOM migration. “Vendor neutral” may not be a suitable term, and “architecture neutral,” “PACS neutral,” “content neutral,” or “third-party neutral” are probably better and preferred terms. Notwithstanding this, the VNA acronym has come to stay in both the medical IT user terminology and in vendor nomenclature, and radiologists need to be aware of its impact in PACS across the globe

International network for comparison of HIV neutralization assays: the NeutNet report II.

Directory of Open Access Journals (Sweden)

Leo Heyndrickx

Full Text Available BACKGROUND: Neutralizing antibodies provide markers for vaccine-induced protective immunity in many viral infections. By analogy, HIV-1 neutralizing antibodies induced by immunization may well predict vaccine effectiveness. Assessment of neutralizing antibodies is therefore of primary importance, but is hampered by the fact that we do not know which assay(s can provide measures of protective immunity. An international collaboration (NeutNet involving 18 different laboratories previously compared different assays using monoclonal antibodies (mAbs and soluble CD4 (Phase I study. METHODS: In the present study (Phase II, polyclonal reagents were evaluated by 13 laboratories. Each laboratory evaluated nine plasmas against an 8 virus panel representing different genetic subtypes and phenotypes. TriMab, a mixture of three mAbs, was used as a positive control allowing comparison of the results with Phase I in a total of nine different assays. The assays used either uncloned virus produced in peripheral blood mononuclear cells (PBMCs (Virus Infectivity Assays, VIA, or Env (gp160-pseudotyped viruses (pseudoviruses, PSV produced in HEK293T cells from molecular clones or from uncloned virus. Target cells included PBMC and genetically engineered cell lines in either single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs including extra- or intra-cellular p24 antigen detection, luciferase, beta-galactosidase or green fluorescent protein (GFP reporter gene expression. FINDINGS: Using TriMab, results of Phase I and Phase II were generally in agreement for six of the eight viruses tested and confirmed that the PSV assay is more sensitive than PBMC (p = 0.014. Comparisons with the polyclonal reagents showed that sensitivities were dependent on both virus and plasma. CONCLUSIONS: Here we further demonstrate clear differences in assay sensitivities that were dependent on both the neutralizing reagent and the virus

International network for comparison of HIV neutralization assays: the NeutNet report II.

Science.gov (United States)

Heyndrickx, Leo; Heath, Alan; Sheik-Khalil, Enas; Alcami, Jose; Bongertz, Vera; Jansson, Marianne; Malnati, Mauro; Montefiori, David; Moog, Christiane; Morris, Lynn; Osmanov, Saladin; Polonis, Victoria; Ramaswamy, Meghna; Sattentau, Quentin; Tolazzi, Monica; Schuitemaker, Hanneke; Willems, Betty; Wrin, Terri; Fenyö, Eva Maria; Scarlatti, Gabriella

2012-01-01

Neutralizing antibodies provide markers for vaccine-induced protective immunity in many viral infections. By analogy, HIV-1 neutralizing antibodies induced by immunization may well predict vaccine effectiveness. Assessment of neutralizing antibodies is therefore of primary importance, but is hampered by the fact that we do not know which assay(s) can provide measures of protective immunity. An international collaboration (NeutNet) involving 18 different laboratories previously compared different assays using monoclonal antibodies (mAbs) and soluble CD4 (Phase I study). In the present study (Phase II), polyclonal reagents were evaluated by 13 laboratories. Each laboratory evaluated nine plasmas against an 8 virus panel representing different genetic subtypes and phenotypes. TriMab, a mixture of three mAbs, was used as a positive control allowing comparison of the results with Phase I in a total of nine different assays. The assays used either uncloned virus produced in peripheral blood mononuclear cells (PBMCs) (Virus Infectivity Assays, VIA), or Env (gp160)-pseudotyped viruses (pseudoviruses, PSV) produced in HEK293T cells from molecular clones or from uncloned virus. Target cells included PBMC and genetically engineered cell lines in either single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs including extra- or intra-cellular p24 antigen detection, luciferase, beta-galactosidase or green fluorescent protein (GFP) reporter gene expression. Using TriMab, results of Phase I and Phase II were generally in agreement for six of the eight viruses tested and confirmed that the PSV assay is more sensitive than PBMC (p = 0.014). Comparisons with the polyclonal reagents showed that sensitivities were dependent on both virus and plasma. Here we further demonstrate clear differences in assay sensitivities that were dependent on both the neutralizing reagent and the virus. Consistent with the Phase I study, we recommend

Material failures observed in Doublet III neutral beamlines

International Nuclear Information System (INIS)

Bailey, E.W.; Colleraine, A.; Doll, D.; Grunloh, H.; Kim, J.; Langhorn, A.; Thurgood, B.

1983-12-01

The Doublet III neutral beam injectors consist of three separable spools two meters in diameter by four meters long overall when assembled. Contained within these spools are the neutralizers, ion dumps, deflecting magnet, calorimeter dumps, cryogenic panels and beam scraping collimators 3,7. To date three beamlines are in operation on Doublet III, and the beams have accumulated operating time of approximately 32 months, with the oldest having been in operation for 18 months. During this time operation of DIII with the neutral beam sources has demonstrated the following: 7.8 MW injected neutrals from three beamlines (6 sources), high β (4.5%), and non-circular plasma shape. The sources have also exhibited a very reliable injected shot history 4, 5, 6, 8. Material failures encountered during the operation of DIII N.B. injectors and the solutions to these failures are described. Failures include cracking of the neutralizer exit collimator due to heating cycles, failure of cyropanel support rods due to cooling cycles, failure of the sliding drive of the moveable calorimeter due to friction

Fault detection and protection system for neutral beam generators on the Neutral Beam Engineering Test Facility (NBETF)

International Nuclear Information System (INIS)

deVries, G.J.; Chesley, K.L.; Owren, H.M.

1983-12-01

Neutral beam sources, their power supplies and instrumentation can be damaged from high voltage sparkdown or from overheating due to excessive currents. The Neutral Beam Engineering Test Facility (NBETF) in Berkeley has protective electronic hardware that senses a condition outside a safe operating range and generates a response to terminate such a fault condition. A description of this system is presented in this paper. 8 references, 2 figures, 2 tables

42 CFR 412.352 - Budget neutrality adjustment.

Science.gov (United States)

2010-10-01

... 42 Public Health 2 2010-10-01 2010-10-01 false Budget neutrality adjustment. 412.352 Section 412.352 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 412.352 Budget neutrality adjustment. For FY 1992 through FY 1995, CMS will determine an adjustment to...

Neutral-particle-beam production and injection

International Nuclear Information System (INIS)

Post, D.; Pyle, R.

1982-07-01

This paper is divided into two sections: the first is a discussion of the interactions of neutral beams with confined plasmas, the second is concerned with the production and diagnosis of the neutral beams. In general we are dealing with atoms, molecules, and ions of the isotopes of hydrogen, but some heavier elements (for example, oxygen) will be mentioned. The emphasis will be on single-particle collisions; selected atomic processes on surfaces will be included

Network Neutrality : A Survey of the Economic Literature

NARCIS (Netherlands)

Schuett, F.

2010-01-01

This paper reviews the small but growing economic literature on network neutrality. It considers a number of possible departures from network neutrality, in particular termination fees, second-degree price discrimination, and vertical foreclosure.

Cooling and trapping neutral atoms with radiative forces

International Nuclear Information System (INIS)

Bagnato, V.S.; Castro, J.C.; Li, M.S.; Zilio, S.C.

1988-01-01

Techniques to slow and trap neutral atoms at high densities with radiative forces are discussed in this review articles. Among several methods of laser cooling, it is emphasized Zeeman Tuning of the electronic levels and frequency-sweeping techniques. Trapping of neutral atoms and recent results obtained in light and magnetic traps are discussed. Techniques to further cool atoms inside traps are presented and the future of laser cooling of neutral atoms by means of radiation pressure is discussed. (A.C.A.S.) [pt

Hydrogen ion species analysis and related neutral beam injection power assessment in the Heliotron E neutral beam injection system

International Nuclear Information System (INIS)

Sano, Fumimichi; Obiki, Tokuhiro; Sasaki, Akihiko; Iiyoshi, Atsuo; Uo, Koji

1982-01-01

The hydrogen ion species in a Heliotron E neutral beam injection system of maximum electric power 6.3 MW were analyzed in order to assess the neutral beam power injected into the torus. The masimum p roton ratio of the cylindrical bucket type ion source used was observed to be more than 90 percent assuming that the angular divergences for the respective species in the beam are the same. The experimental data are compared with calculations using a particle balance model. The analysis indicates that the net injection power reaches nearly 2.7 MW at the optimal conditions of the system considering the geometrical limitation of the neutral beam path. (author)

Naturally selected hepatitis C virus polymorphisms confer broad neutralizing antibody resistance.

Science.gov (United States)

Bailey, Justin R; Wasilewski, Lisa N; Snider, Anna E; El-Diwany, Ramy; Osburn, William O; Keck, Zhenyong; Foung, Steven K H; Ray, Stuart C

2015-01-01

For hepatitis C virus (HCV) and other highly variable viruses, broadly neutralizing mAbs are an important guide for vaccine development. The development of resistance to anti-HCV mAbs is poorly understood, in part due to a lack of neutralization testing against diverse, representative panels of HCV variants. Here, we developed a neutralization panel expressing diverse, naturally occurring HCV envelopes (E1E2s) and used this panel to characterize neutralizing breadth and resistance mechanisms of 18 previously described broadly neutralizing anti-HCV human mAbs. The observed mAb resistance could not be attributed to polymorphisms in E1E2 at known mAb-binding residues. Additionally, hierarchical clustering analysis of neutralization resistance patterns revealed relationships between mAbs that were not predicted by prior epitope mapping, identifying 3 distinct neutralization clusters. Using this clustering analysis and envelope sequence data, we identified polymorphisms in E2 that confer resistance to multiple broadly neutralizing mAbs. These polymorphisms, which are not at mAb contact residues, also conferred resistance to neutralization by plasma from HCV-infected subjects. Together, our method of neutralization clustering with sequence analysis reveals that polymorphisms at noncontact residues may be a major immune evasion mechanism for HCV, facilitating viral persistence and presenting a challenge for HCV vaccine development.

Ballistic-neutralized chamber transport of intense heavy ion beams

International Nuclear Information System (INIS)

Rose, D.V.; Welch, D.R.; Oliver, B.V.; Clark, R.E.; Sharp, W.M.; Friedman, A.

2001-01-01

Two-dimensional particle-in-cell simulations of intense heavy ion beams propagating in an inertial confinement fusion (ICF) reactor chamber are presented. The ballistic-neutralized transport scheme studied uses 4 GeV Pb +1 ion beams injected into a low-density, gas-filled reactor chamber and the beam is ballistically focused onto an ICF target before entering the chamber. Charge and current neutralization of the beam is provided by the low-density background gas. The ballistic-neutralized simulations include stripping of the beam ions as the beam traverses the chamber as well as ionization of the background plasma. In addition, a series of simulations are presented that explore the charge and current neutralization of the ion beam in an evacuated chamber. For this vacuum transport mode, neutralizing electrons are only drawn from sources near the chamber entrance

Is the stoichiometry of the europium nitrate complexes with neutral organophosphorus extractants be anticipated?

International Nuclear Information System (INIS)

Beudaert, Ph.; Lamare, V.; Wipff, G.

2001-01-01

Molecular dynamics simulations have been performed in water on europium nitrate complexes with three neutral organophosphorus extractants (TBP, TPPO and CMPO) in order to determine on what criteria it is possible to obtain by simulations the experimental 1:3 stoichiometry in organic solution. This stoichiometry was investigated by progressive saturation of the cation coordination sphere. When the nitrate counter-ions are bidentate, the 1:3 stoichiometry corresponds to the degree of saturation where the interaction energy between europium and water becomes repulsive. Beyond this stoichiometry, complexes with TPPO and CMPO are unstable, although a 1:4 complex with TBP may exist but its formation appears to be energetically unfavored. (author)

On the role of neutral flow in field-aligned currents

Science.gov (United States)

Mannucci, Anthony J.; Verkhoglyadova, Olga P.; Meng, Xing; McGranaghan, Ryan

2018-01-01

In this brief note we explore the role of the neutral atmosphere in magnetosphere-ionosphere coupling. We analyze momentum balance in the ion rest frame to form hypotheses regarding the role of neutral momentum in the lower ionosphere during geomagnetic storms. Neutral momentum that appears in the ion rest frame is likely the result of momentum imparted to ionospheric ions by solar wind flow and the resultant magnetospheric dynamics. The resulting ion-neutral collisions lead to the existence of an electric field. Horizontal electron flow balances the momentum supplied by this electric field. We suggest a possible role played by the neutral atmosphere in generating field-aligned currents due to local auroral heating. Our physical interpretation suggests that thermospheric neutral dynamics plays a complementary role to the high-latitude field-aligned currents and electric fields resulting from magnetospheric dynamics.

Design of a negative ion neutral beam system for TNS

International Nuclear Information System (INIS)

Easoz, J.R.

1978-05-01

A conceptual design of a neutral beam line based on the neutralization of negative deuterium ions is presented. This work is a detailed design of a complete neutral beam line based on using negative ions from a direct extraction source. Anticipating major technological advancements, beam line components have been scaled including the negative ion sources and components for the direct energy recovery of charged beams and high speed cryogenic pumping. With application to the next step in experimental fusion reactors (TNS), the neutral beam injector system that has been designed provides 10 MW of 200 keV neutral deuterium atoms. Several arms are required for plasma ignition

Neutral heavy lepton production in e+-e- collisions

International Nuclear Information System (INIS)

Ragiadakos, C.

1977-01-01

The cross-sections of the weak production of different kinds of neutral heavy leptons in e + -e - collisions are calculated and their signatures are studied. A possible electromagnetic production of neutral heavy leptons is also considered

Catalytic copolymerization of CO and ethylene with a charge neutral palladium(II) zwitterion.

Science.gov (United States)

Lu, Connie C; Peters, Jonas C

2002-05-15

The synthesis of a zwitterionic Pd(II) complex supported by an anionic bis(phosphino)borate ligand, Ph(2)B(CH(2)PPh(2))(2) (abbreviated as [Ph(2)BP(2)]), is reported. The new complex, [Ph(2)BP(2)]PdMe(THF), is active for CO and ethylene copolymerization. The copolymerization activity and polyketone molecular weight for the neutral, zwitterionic system are compared with those for the cationic systems [R(2)E(CH(2)PPh(2))(2)PdMe(THF)][B(C(6)F(5))(4)] where ER(2) = SiPh(2) and CH(2). Surprisingly, the more electron rich zwitterionic system is a catalyst of activity comparable to that of the more conventional cationic systems.

DnaSAM: Software to perform neutrality testing for large datasets with complex null models.

Science.gov (United States)

Eckert, Andrew J; Liechty, John D; Tearse, Brandon R; Pande, Barnaly; Neale, David B

2010-05-01

Patterns of DNA sequence polymorphisms can be used to understand the processes of demography and adaptation within natural populations. High-throughput generation of DNA sequence data has historically been the bottleneck with respect to data processing and experimental inference. Advances in marker technologies have largely solved this problem. Currently, the limiting step is computational, with most molecular population genetic software allowing a gene-by-gene analysis through a graphical user interface. An easy-to-use analysis program that allows both high-throughput processing of multiple sequence alignments along with the flexibility to simulate data under complex demographic scenarios is currently lacking. We introduce a new program, named DnaSAM, which allows high-throughput estimation of DNA sequence diversity and neutrality statistics from experimental data along with the ability to test those statistics via Monte Carlo coalescent simulations. These simulations are conducted using the ms program, which is able to incorporate several genetic parameters (e.g. recombination) and demographic scenarios (e.g. population bottlenecks). The output is a set of diversity and neutrality statistics with associated probability values under a user-specified null model that are stored in easy to manipulate text file. © 2009 Blackwell Publishing Ltd.

Evidence for parity nonconservation in the weak neutral current

International Nuclear Information System (INIS)

Benvenuti, A.; Cline, D.; Messing, F.; Ford, W.; Imlay, R.; Ling, T.Y.; Mann, A.K.; Reeder, D.D.; Rubbia, C.; Stefanski, R.; Sulak, L.; Wanderer, P.

1976-01-01

Measurements of R/sup nu/ and R/sup nu-bar/, the ratios of neutral current to charged current ν and nu-bar cross sections, yield neutral current rates for ν and nu-bar that are consistent with a pure V-A interaction but 3 standard deviations from pure V or pure A, indicating the presence of parity nonconservation in the weak neutral current

Neutral currents without gauge theory prejudices

International Nuclear Information System (INIS)

Sakurai, J.J.

1976-01-01

The measurement of weak neutral current processes allows a determination of the space-time structure and the isospin structure of these currents. The inclusive production data and the elastic neutrino electron scattering rules out a pure V or A structure of the current. A pure isoscalar current is in disagreement with the experimental data for the one pion production off neutrinos. Further aspects of the neutral current can be determined in neutrino-nucleus-scattering experiments. (BJ) [de

The control of powerful neutral beams

International Nuclear Information System (INIS)

Theil, E.; Jacobson, V.

1986-01-01

While significant progress has been made in the development of neutral beams for the heating and sustaining of plasmas in large fusion experiments, the control of such devices has largely been a matter of hardware interlocks and operator experience. The need for computer-assisted control becomes more evident, however, with the initiation of multi-beamline experiments. This paper describes a software system that incorporates simple mathematical models coupled to Kalman filters for control of the high power (6 to 8 MW) beams currently under development at Lawrence Berkeley Laboratory's Neutral Beam Engineering Test Facility. Among the principal features of the system are: reduction of a large number of operator variables to just a few (usually one or two); the ability to describe most of the major neutral beams in use and under development; a foundation resting on statistical data analysis and control system principles rather than rules-of-thumb

Compression and ablation of the photo-irradiated molecular cloud the Orion Bar.

Science.gov (United States)

Goicoechea, Javier R; Pety, Jérôme; Cuadrado, Sara; Cernicharo, José; Chapillon, Edwige; Fuente, Asunción; Gerin, Maryvonne; Joblin, Christine; Marcelino, Nuria; Pilleri, Paolo

2016-09-08

The Orion Bar is the archetypal edge-on molecular cloud surface illuminated by strong ultraviolet radiation from nearby massive stars. Our relative closeness to the Orion nebula (about 1,350 light years away from Earth) means that we can study the effects of stellar feedback on the parental cloud in detail. Visible-light observations of the Orion Bar show that the transition between the hot ionized gas and the warm neutral atomic gas (the ionization front) is spatially well separated from the transition between atomic and molecular gas (the dissociation front), by about 15 arcseconds or 6,200 astronomical units (one astronomical unit is the Earth-Sun distance). Static equilibrium models used to interpret previous far-infrared and radio observations of the neutral gas in the Orion Bar (typically at 10-20 arcsecond resolution) predict an inhomogeneous cloud structure comprised of dense clumps embedded in a lower-density extended gas component. Here we report one-arcsecond-resolution millimetre-wave images that allow us to resolve the molecular cloud surface. In contrast to stationary model predictions, there is no appreciable offset between the peak of the H 2 vibrational emission (delineating the H/H 2 transition) and the edge of the observed CO and HCO + emission. This implies that the H/H 2 and C + /C/CO transition zones are very close. We find a fragmented ridge of high-density substructures, photoablative gas flows and instabilities at the molecular cloud surface. The results suggest that the cloud edge has been compressed by a high-pressure wave that is moving into the molecular cloud, demonstrating that dynamical and non-equilibrium effects are important for the cloud evolution.

Solvent extraction of cerium (III) with high molecular weight amines

International Nuclear Information System (INIS)

Chatterjee, A.; Basu, S.

1992-01-01

The use of high molecular weight amines in the extraction of cerium (III) as EDTA complex from neutral aqueous medium is reported. The extraction condition was optimised from the study of effects of several variables like concentration of amine and EDTA pH nature of diluents etc. The method has been applied for the determination of cerium in few mineral samples. (author). 7 refs., 5 tabs

3He neutral current detectors at SNO

International Nuclear Information System (INIS)

Elliott, S.R.; Browne, M.C.; Doe, P.J.

1998-01-01

The flux of solar neutrinos measured via charged and neutral current interactions can provide a model independent test of neutrino oscillations. Since the Sudbury Neutrino Observatory uses heavy water as a target, it has a large sensitivity to both interactions. A technique for observing the neutral current breakup of the deuteron using 3 He proportional counters is described

Solvent dielectric effect and side chain mutation on the structural stability of Burkholderia cepacia lipase active site: a quantum mechanical/molecular mechanics study.

Science.gov (United States)

Tahan, A; Monajjemi, M

2011-12-01

Quantum mechanical and molecular dynamics methods were used to analyze the structure and stability of neutral and zwitterionic configurations of the extracted active site sequence from a Burkholderia cepacia lipase, histidyl-seryl-glutamin (His86-Ser87-Gln88) and its mutated form, histidyl-cysteyl-glutamin (His86-Cys87-Gln88) in vacuum and different solvents. The effects of solvent dielectric constant, explicit and implicit water molecules and side chain mutation on the structure and stability of this sequence in both neutral and zwitterionic forms are represented. The quantum mechanics computations represent that the relative stability of zwitterionic and neutral configurations depends on the solvent structure and its dielectric constant. Therefore, in vacuum and the considered non-polar solvents, the neutral form of the interested sequences is more stable than the zwitterionic form, while their zwitterionic form is more stable than the neutral form in the aqueous solution and the investigated polar solvents in most cases. However, on the potential energy surfaces calculated, there is a barrier to proton transfer from the positively charged ammonium group to the negatively charged carboxylat group or from the ammonium group to the adjacent carbonyl oxygen and or from side chain oxygen and sulfur to negatively charged carboxylat group. Molecular dynamics simulations (MD) were also performed by using periodic boundary conditions for the zwitterionic configuration of the hydrated molecules in a box of water molecules. The obtained results demonstrated that the presence of explicit water molecules provides the more compact structures of the studied molecules. These simulations also indicated that side chain mutation and replacement of sulfur with oxygen leads to reduction of molecular flexibility and packing.

Stability of Neutral Fractional Neural Networks with Delay

Institute of Scientific and Technical Information of China (English)

LI Yan; JIANG Wei; HU Bei-bei

2016-01-01

This paper studies stability of neutral fractional neural networks with delay. By introducing the definition of norm and using the uniform stability, the sufficient condition for uniform stability of neutral fractional neural networks with delay is obtained.

Modelling of neutral particle transport in divertor plasma

International Nuclear Information System (INIS)

Kakizuka, Tomonori; Shimizu, Katsuhiro

1995-01-01

An outline of the modelling of neutral particle transport in the diverter plasma was described in the paper. The characteristic properties of divertor plasma were largely affected by interaction between neutral particles and divertor plasma. Accordingly, the behavior of neutral particle should be investigated quantitatively. Moreover, plasma and neutral gas should be traced consistently in the plasma simulation. There are Monte Carlo modelling and the neutral gas fluid modelling as the transport modelling. The former need long calculation time, but it is able to make the physical process modelling. A ultra-large parallel computer is good for the former. In spite of proposing some kinds of models, the latter has not been established. At the view point of reducing calculation time, a work station is good for the simulation of the latter, although some physical problems have not been solved. On the Monte Carlo method particle modelling, reducing the calculation time and introducing the interaction of particles are important subjects to develop 'the evolutional Monte Carlo Method'. To reduce the calculation time, two new methods: 'Implicit Monte Carlo method' and 'Free-and Diffusive-Motion Hybrid Monte-Carlo method' have been developing. (S.Y.)

Are Synonymous Substitutions in Flowering Plant Mitochondria Neutral?

Science.gov (United States)

Wynn, Emily L; Christensen, Alan C

2015-10-01

Angiosperm mitochondrial genes appear to have very low mutation rates, while non-gene regions expand, diverge, and rearrange quickly. One possible explanation for this disparity is that synonymous substitutions in plant mitochondrial genes are not truly neutral and selection keeps their occurrence low. If this were true, the explanation for the disparity in mutation rates in genes and non-genes needs to consider selection as well as mechanisms of DNA repair. Rps14 is co-transcribed with cob and rpl5 in most plant mitochondrial genomes, but in some genomes, rps14 has been duplicated to the nucleus leaving a pseudogene in the mitochondria. This provides an opportunity to compare neutral substitution rates in pseudogenes with synonymous substitution rates in the orthologs. Genes and pseudogenes of rps14 have been aligned among different species and the mutation rates have been calculated. Neutral substitution rates in pseudogenes and synonymous substitution rates in genes are significantly different, providing evidence that synonymous substitutions in plant mitochondrial genes are not completely neutral. The non-neutrality is not sufficient to completely explain the exceptionally low mutation rates in land plant mitochondrial genomes, but selective forces appear to play a small role.

Neutral and plasma shielding model for pellet ablation

International Nuclear Information System (INIS)

Houlberg, W.A.; Milora, S.L.; Attenberger, S.E.

1987-10-01

The neutral gas shielding model for ablation of frozen hydrogenic pellets is extended to include the effects of an initial Maxwelliam distribution of incident electron energies; a cold plasma shield outside the neutral shield and extended along the magnetic field; energetic neutral beam ions and alpha particles; and self-limiting electron ablation in the collisionless plasma limit. Including the full electron distribution increases ablation, but adding the cold ionized shield reduces ablation; the net effect is a modest reduction in pellet penetration compared with the monoenergetic electron neutral shielding model with no plasma shield. Unlike electrons, fast ions can enter the neutral shield directly without passing through the cold ionized shield because their gyro-orbits are typically larger than the diameter of the cold plasma tube. Fast alpha particles should not enhance the ablation rate unless their population exceeds that expected from local classical thermalization. Fast beam ions, however, may enhance ablation in the plasma periphery if their population is high enough. Self-limiting ablation in the collisionless limit leads to a temporary distortion of the original plasma electron Maxwellian distribution function through preferential depopulation of the higher-energy electrons. 23 refs., 9 figs

Confinement of pure electron plasmas in the Columbia Non-neutral Torus

International Nuclear Information System (INIS)

Berkery, John W.; Pedersen, Thomas Sunn; Kremer, Jason P.; Marksteiner, Quinn R.; Lefrancois, Remi G.; Hahn, Michael S.; Brenner, Paul W.

2007-01-01

The Columbia Non-neutral Torus (CNT) [T. S. Pedersen, J. P. Kremer, R. G. Lefrancois, Q. Marksteiner, N. Pomphrey, W. Reiersen, F. Dahlgreen, and X. Sarasola, Fusion Sci. Technol. 50, 372 (2006)] is a stellarator used to study non-neutral plasmas confined on magnetic surfaces. A detailed experimental study of confinement of pure electron plasmas in CNT is described here. Electrons are introduced into the magnetic surfaces by placing a biased thermionic emitter on the magnetic axis. As reported previously, the insulated rods holding this and other emitter filaments contribute to the radial transport by charging up negatively and creating ExB convective transport cells. A model for the rod-driven transport is presented and compared to the measured transport rates under a number of different conditions, finding good agreement. Neutrals also drive transport, and by varying the neutral pressure in the experiment, the effects of rod-driven and neutral-driven transport are separated. The neutral-driven electron loss rate scales linearly with neutral pressure. The neutral driven transport, presumably caused by electron-neutral collisions, is much greater than theoretical estimates for neoclassical diffusion in a classical stellarator with strong radial electric fields. In fact the confinement time is on the order of the electron-neutral collision time. Ion accumulation, electron attachment, and other effects are considered, but do not explain the observed transport rates

PDX neutral-beam reionization losses

International Nuclear Information System (INIS)

Kugel, H.W.; Dylla, H.F.; Eubank, H.P.; Kozub, T.A.; Moore, R.; Schilling, G.; Stewart, L.D.; von Halle, A.; Williams, M.D.

1982-02-01

Reionization losses for 1.5 MW H 0 and 2 MW D 0 neutral beams injected into the PDX tokamak were studied using pressure gauges, photo-transistors, thermocouples, surface shielding, and surface sample analysis. Considerable outgassing of conventionally prepared 304SS ducts occurred during initial injections and gradually decreased with the cumulative absorption of beam power. Reionization power losses are presently about 5% in the ducts and about 12% total for a beamline including the duct. Present duct pressures are attributed primarily to gas from the ion source and neutralizer with much smaller contributions from residual wall desorption. Physical mechanisms for the observed duct outgassing are discussed

On the role of neutral flow in field-aligned currents

Directory of Open Access Journals (Sweden)

A. J. Mannucci

2018-01-01

Full Text Available In this brief note we explore the role of the neutral atmosphere in magnetosphere–ionosphere coupling. We analyze momentum balance in the ion rest frame to form hypotheses regarding the role of neutral momentum in the lower ionosphere during geomagnetic storms. Neutral momentum that appears in the ion rest frame is likely the result of momentum imparted to ionospheric ions by solar wind flow and the resultant magnetospheric dynamics. The resulting ion-neutral collisions lead to the existence of an electric field. Horizontal electron flow balances the momentum supplied by this electric field. We suggest a possible role played by the neutral atmosphere in generating field-aligned currents due to local auroral heating. Our physical interpretation suggests that thermospheric neutral dynamics plays a complementary role to the high-latitude field-aligned currents and electric fields resulting from magnetospheric dynamics.

Kinetic Properties of the Neutral Solar Wind

International Nuclear Information System (INIS)

Florinski, V.; Heerikhuisen, J.

2017-01-01

Charge-exchange collisions between the solar wind protons and interstellar hydrogen produce a distinctive population of neutral hydrogen streaming radially at nearly the solar-wind speed. This tenuous population, known as the neutral solar wind (NSW) is thought to play a key role in the appearance of the Interplanetary Boundary EXplorer ribbon, a bright circular band in the sky that is the source of neutral hydrogen with energies near 1 keV. According to the leading model of the ribbon, the velocity distribution of NSW hydrogen is imparted on the pickup ions (PUIs) generated via charge exchange with the interstellar protons beyond the heliopause, and in this way controls the stability of the resulting ring distribution of PUIs against hydromagnetic wave generation. In this paper, we examine the velocity distributions of the NSW atoms in the heliosphere and the outer heliosheath regions by following the phase-space trajectories of the Boltzmann equation. It is demonstrated that these distributions are highly anisotropic, with the parallel (radial) temperature greatly exceeding the perpendicular temperature. Ions picked up near 90° from the anisotropic NSW would form a stable ring distribution capable of generating the ribbon flux. We also discuss a second population of neutrals born in charge transfer collisions with interstellar PUIs, the so-called neutralized pickup ion (NPI) component. Their high thermal velocities translate into large parallel velocity spread of the daughter ribbon PUIs, which would adversely affect plasma stability in local interstellar space.

Kinetic Properties of the Neutral Solar Wind

Science.gov (United States)

Florinski, V.; Heerikhuisen, J.

2017-03-01

Charge-exchange collisions between the solar wind protons and interstellar hydrogen produce a distinctive population of neutral hydrogen streaming radially at nearly the solar-wind speed. This tenuous population, known as the neutral solar wind (NSW) is thought to play a key role in the appearance of the Interplanetary Boundary EXplorer ribbon, a bright circular band in the sky that is the source of neutral hydrogen with energies near 1 keV. According to the leading model of the ribbon, the velocity distribution of NSW hydrogen is imparted on the pickup ions (PUIs) generated via charge exchange with the interstellar protons beyond the heliopause, and in this way controls the stability of the resulting ring distribution of PUIs against hydromagnetic wave generation. In this paper, we examine the velocity distributions of the NSW atoms in the heliosphere and the outer heliosheath regions by following the phase-space trajectories of the Boltzmann equation. It is demonstrated that these distributions are highly anisotropic, with the parallel (radial) temperature greatly exceeding the perpendicular temperature. Ions picked up near 90° from the anisotropic NSW would form a stable ring distribution capable of generating the ribbon flux. We also discuss a second population of neutrals born in charge transfer collisions with interstellar PUIs, the so-called neutralized pickup ion (NPI) component. Their high thermal velocities translate into large parallel velocity spread of the daughter ribbon PUIs, which would adversely affect plasma stability in local interstellar space.

Neutralization of positive particle beams by electron trapping

International Nuclear Information System (INIS)

Mobley, R.M.; Irani, A.A.; LeMaire, J.L.; Maschke, A.W.

1977-01-01

Initial results are presented of a planned series of experimental tests of positive ion beam neutralization, involving transverse space charge studies of a 720 keV 60mA H + beam in a drift region of 4.6 meters. Two conclusions drawn from the data are: (1) the change in transmission observed is consistent with complete neutralization in the drift pipe for grounded or negative electrodes, and with complete de-neutralization in the case of greater than +240 V electrodes; and (2) background gas ionization cannot be the main source of electrons

Neutral beam systems for the magnetic fusion program

International Nuclear Information System (INIS)

Beal, J.W.; Staten, H.S.

1977-01-01

The attainment of economic, safe fusion power has been described as the most sophisticated scientific problem ever attacked by mankind. The presently established goal of the magnetic fusion program is to develop and demonstrate pure fusion central electric power stations for commercial applications. Neutral beam heating systems are a basic component of the tokamak and mirror experimental fusion plasma confinement devices. The requirements placed upon neutral beam heating systems are reviewed. The neutral beam systems in use or being developed are presented. Finally, the needs of the future are discussed

Appropriate materials and preparation techniques for polycrystalline-thin-film thermophotovoltaic cells

Science.gov (United States)

Dhere, Neelkanth G.

1997-03-01

Polycrystalline-thin-film thermophotovoltaic (TPV) cells have excellent potential for reducing the cost of TPV generators so as to address the hitherto inaccessible and highly competitive markets such as self-powered gas-fired residential warm air furnaces and energy-efficient electric cars, etc. Recent progress in polycrystalline-thin-film solar cells have made it possible to satisfy the diffusion length and intrinsic junction rectification criteria for TPV cells operating at high fluences. Continuous ranges of direct bandgaps of the ternary and pseudoternary compounds such as Hg1-xCdxTe, Pb1-xCdxTe, Hg1-xZnxTe, and Pb1-xZnxS cover the region of interest of 0.50-0.75 eV for efficient TPV conversion. Other ternary and pseudoternary compounds which show direct bandgaps in most of or all of the 0.50-0.75 eV range are Pb1-xZnxTe, Sn1-xCd2xTe2, Pb1-xCdxSe, Pb1-xZnxSe, and Pb1-xCdxS. Hg1-xCdxTe (with x~0.21) has been studied extensively for infrared detectors. PbTe and Pb1-xSnxTe have also been studied for infrared detectors. Not much work has been carried out on Hg1-xZnxTe thin films. Hg1-xCdxTe and Pb1-xCdxTe alloys cover a wide range of cut-off wavelengths from the far infrared to the near visible. Acceptors and donors are introduced in these materials by excess non-metal (Te) and excess metal (Hg and Pb) respectively. Extrinsic acceptor impurities are Cu, Au, and As while and In and Al are donor impurities. Hg1-xCdxTe thin films have been deposited by isothermal vapor-phase epitaxy (VPE), liquid phase epitaxy (LPE), hot-wall metalorganic chemical vapor deposition (MOCVD), electrodeposition, sputtering, molecular beam epitaxy (MBE), laser-assisted evaporation, and vacuum evaporation with or without hot-wall enclosure. The challenge in the preparation of Hg1-xCdxTe is to provide excess mercury incidence rate, to optimize the deposition parameters for enhanced mercury incorporation, and to achieve the requisite stoichiometry, grain size, and doping. MBE and MOCVD

Dynamics of ion beam charge neutralization by ferroelectric plasma sources

Energy Technology Data Exchange (ETDEWEB)

Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C. [Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)

2016-04-15

Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar{sup +} beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established ∼5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-μs surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of μs after the high voltage pulse is applied. It is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.

HIV-1 binding and neutralizing antibodies of injecting drug users

Directory of Open Access Journals (Sweden)

E.P. Ouverney

2005-09-01

Full Text Available Previous studies have demonstrated a stronger seroreactivity against some synthetic peptides responsible for inducing neutralizing antibodies in injecting drug users (IDU compared to that of individuals sexually infected with HIV-1 (S, but the effectiveness in terms of the neutralizing ability of these antibodies has not been evaluated. Our objective was to study the humoral immune response of IDU by determining the specificity of their antibodies and the presence of neutralizing antibodies. The neutralization capacity against the HIV-1 isolate MN (genotype B, the primary HIV-1 isolate 95BRRJ021 (genotype F, and the seroreactivity with peptides known to induce neutralizing antibodies, from the V2 and V3 loops of different HIV-1 subtypes, were analyzed. Seroreactivity indicates that IDU plasma are more likely to recognize a broader range of peptides than S plasma, with significantly higher titers, especially of V3 peptides. Similar neutralization frequencies of the MN isolate were observed in plasma of the IDU (16/47 and S (20/60 groups in the 1:10 dilution. The neutralization of the 95BRRJ021 isolate was more frequently observed for plasma from the S group (15/23 than from the IDU group (15/47, P = 0.0108. No correlation between neutralization and seroreactivity with the peptides tested was observed. These results suggest that an important factor responsible for the extensive and broad humoral immune response observed in IDU is their infection route. There was very little difference in neutralizing antibody response between the IDU and S groups despite their differences in seroreactivity and health status.

New insights into heat induced structural changes of pectin methylesterase on fluorescence spectroscopy and molecular modeling basis

Science.gov (United States)

Nistor, Oana Viorela; Stănciuc, Nicoleta; Aprodu, Iuliana; Botez, Elisabeta

2014-07-01

Heat-induced structural changes of Aspergillus oryzae pectin methylesterase (PME) were studied by means of fluorescence spectroscopy and molecular modeling, whereas the functional enzyme stability was monitored by inactivation studies. The fluorescence spectroscopy experiments were performed at two pH value (4.5 and 7.0). At both pH values, the phase diagrams were linear, indicating the presence of two molecular species induced by thermal treatment. A red shift of 7 nm was observed at neutral pH by increasing temperature up to 60 °C, followed by a blue shift of 4 nm at 70 °C, suggesting significant conformational rearrangements. The quenching experiments using acrylamide and iodide demonstrate a more flexible conformation of enzyme with increasing temperature, especially at neutral pH. The experimental results were complemented with atomic level observations on PME model behavior after performing molecular dynamics simulations at different temperatures. The inactivation kinetics of PME in buffer solutions was fitted using a first-order kinetics model, resulting in activation energy of 241.4 ± 7.51 kJ mol-1.

Apparatus for neutralization of accelerated ions

International Nuclear Information System (INIS)

Fink, J.H.; Frank, A.M.

1979-01-01

Apparatus is described for neutralization of a beam of accelerated ions, such as hydrogen negative ions (H - ), using relatively efficient strip diode lasers which emit monochromatically at an appropriate wavelength (lambda = 8000 A for H - ions) to strip the excess electrons by photodetachment. A cavity, formed by two or more reflectors spaced apart, causes the laser beams to undergo multiple reflections within the cavity, thus increasing the efficiency and reducing the illumination required to obtain an acceptable percentage (approx. 85%) of neutralization

STATISTICAL ANALYSIS OF THE HEAVY NEUTRAL ATOMS MEASURED BY IBEX

International Nuclear Information System (INIS)

Park, Jeewoo; Kucharek, Harald; Möbius, Eberhard; Galli, André; Livadiotis, George; Fuselier, Steve A.; McComas, David J.

2015-01-01

We investigate the directional distribution of heavy neutral atoms in the heliosphere by using heavy neutral maps generated with the IBEX-Lo instrument over three years from 2009 to 2011. The interstellar neutral (ISN) O and Ne gas flow was found in the first-year heavy neutral map at 601 keV and its flow direction and temperature were studied. However, due to the low counting statistics, researchers have not treated the full sky maps in detail. The main goal of this study is to evaluate the statistical significance of each pixel in the heavy neutral maps to get a better understanding of the directional distribution of heavy neutral atoms in the heliosphere. Here, we examine three statistical analysis methods: the signal-to-noise filter, the confidence limit method, and the cluster analysis method. These methods allow us to exclude background from areas where the heavy neutral signal is statistically significant. These methods also allow the consistent detection of heavy neutral atom structures. The main emission feature expands toward lower longitude and higher latitude from the observational peak of the ISN O and Ne gas flow. We call this emission the extended tail. It may be an imprint of the secondary oxygen atoms generated by charge exchange between ISN hydrogen atoms and oxygen ions in the outer heliosheath

A Study of Charge-Exchange Neutrals from a Rotating Plasma

DEFF Research Database (Denmark)

Jørgensen, L. W.; Sillesen, Alfred Hegaard

1980-01-01

Measurements of charge-exchange neutrals leaving a rotating plasma (a puffatron device) are reported. Neutrals are observed only during the breakdown phase (2-3 mu s) indicating that the created plasma is fully ionized. Several energy spectra of the neutrals for different plasma parameters are ob....... Neutral particle measurements at different distances from the puffatron midplane show ionization velocities parallel with the magnetic field of about 2*104 ms-1 and plasma expansion velocities of about 5-6*104 ms-1 corresponding to an electron temperature of about 25 eV.......Measurements of charge-exchange neutrals leaving a rotating plasma (a puffatron device) are reported. Neutrals are observed only during the breakdown phase (2-3 mu s) indicating that the created plasma is fully ionized. Several energy spectra of the neutrals for different plasma parameters...... are obtained. These spectra are grossly explained using a single-particle orbit model of the plasma ions. Assuming a Maxwellian distribution for the spread in the ion Larmor energy for the central part of the measured energy spectra, it is possible to determine the ion energy during the breakdown phase...

Neutralized drift compression experiments with a high-intensity ion beam

International Nuclear Information System (INIS)

Roy, P.K.; Yu, S.S.; Waldron, W.L.; Anders, A.; Baca, D.; Barnard, J.J.; Bieniosek, F.M.; Coleman, J.; Davidson, R.C.; Efthimion, P.C.; Eylon, S.; Friedman, A.; Gilson, E.P.; Greenway, W.G.; Henestroza, E.; Kaganovich, I.; Leitner, M.; Logan, B.G.; Sefkow, A.B.; Seidl, P.A.; Sharp, W.M.; Thoma, C.; Welch, D.R.

2007-01-01

To create high-energy density matter and fusion conditions, high-power drivers, such as lasers, ion beams, and X-ray drivers, may be employed to heat targets with short pulses compared to hydro-motion. Both high-energy density physics and ion-driven inertial fusion require the simultaneous transverse and longitudinal compression of an ion beam to achieve high intensities. We have previously studied the effects of plasma neutralization for transverse beam compression. The scaled experiment, the Neutralized Transport Experiment (NTX), demonstrated that an initially un-neutralized beam can be compressed transversely to ∼1 mm radius when charge neutralization by background plasma electrons is provided. Here, we report longitudinal compression of a velocity-tailored, intense, neutralized 25 mA K + beam at 300 keV. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhances the beam peak current by a factor of 50 and produces a pulse duration of about 3 ns. The physics of longitudinal compression, experimental procedure, and the results of the compression experiments are presented

Theoretical Study of near Neutrality. II. Effect of Subdivided Population Structure with Local Extinction and Recolonization

Science.gov (United States)

Ohta, T.

1992-01-01

There are several unsolved problems concerning the model of nearly neutral mutations. One is the interaction of subdivided population structure and weak selection that spatially fluctuates. The model of nearly neutral mutations whose selection coefficient spatially fluctuates has been studied by adopting the island model with periodic extinction-recolonization. Both the number of colonies and the migration rate play significant roles in determining mutants' behavior, and selection is ineffective when the extinction-recolonization is frequent with low migration rate. In summary, the number of mutant substitutions decreases and the polymorphism increases by increasing the total population size, and/or decreasing the extinction-recolonization rate. However, by increasing the total size of the population, the mutant substitution rate does not become as low when compared with that in panmictic populations, because of the extinction-recolonization, especially when the migration rate is limited. It is also found that the model satisfactorily explains the contrasting patterns of molecular polymorphisms observed in sibling species of Drosophila, including heterozygosity, proportion of polymorphism and fixation index. PMID:1582566

Characterization of the alkaline/neutral invertase gene in Dendrobium officinale and its relationship with polysaccharide accumulation.

Science.gov (United States)

Gao, F; Cao, X F; Si, J P; Chen, Z Y; Duan, C L

2016-05-06

Dendrobium officinale is one of the most well-known traditional Chinese medicines, and polysaccharide is its main active ingredient. Many studies have investigated the synthesis and accumulation mechanisms of polysaccharide, but until recently, little was known about the molecular mechanism of how polysaccharide is synthesized because no related genes have been cloned. In this study, we cloned an alkaline/neutral invertase gene from D. officinale (DoNI) by the rapid amplification of cDNA ends (RACE) method. DoNI was 2231 bp long and contained an open reading frame that predicted a 62.8-kDa polypeptide with 554-amino acid residues. An alkaline/neutral invertase conserved domain was predicted from this deduced amino acid sequence, and DoNI had a similar deduced amino acid sequence to Setaria italica and Oryza brachyantha. We also found that DoNI expression in different tissues was closely related to DoNI activity, and more importantly, polysaccharide level. Our results indicate that DoNI is associated with polysaccharide accumulation in D. officinale.

Neutralization kinetics of charged polymer surface

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, S. [Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Mukherjee, M. [Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India)], E-mail: manabendra.mukherjee@saha.ac.in

2008-04-15

In case of photoemission spectroscopy of an insulating material the data obtained from the charged surface are normally distorted due to differential charging. Recently, we have developed a controlled surface neutralization technique to study the kinetics of the surface charging. Using this technique and the associated data analysis scheme with an effective charging model, quantitative information from the apparently distorted photoemission data from PTFE surfaces were extracted. The surface charging was controlled by tuning the electron flood current as well as the X-ray intensity. The effective model was found to describe the charging consistently for both the cases. It was shown that the non-linear neutralization response of differential charging around a critical neutralizing electron flux or a critical X-ray emission current was due to percolation of equipotential surface domains. The obtained value of the critical percolation exponent {gamma} close to unity indicates a percolation similar to that of avalanche breakdown or chain reaction.

Antibody neutralization of retargeted measles viruses

Science.gov (United States)

Lech, Patrycja J.; Pappoe, Roland; Nakamura, Takafumi; Tobin, Gregory J.; Nara, Peter L.; Russell, Stephen J.

2014-01-01

The measles virus (MV) vaccine lineage is a promising oncolytic but prior exposure to the measles vaccine or wild-type MV strains limits treatment utility due to the presence of anti-measles antibodies. MV entry can be redirected by displaying a polypeptide ligand on the Hemagglutinin (H) C-terminus. We hypothesized that retargeted MV would escape neutralization by monoclonal antibodies (mAbs) recognizing the H receptor-binding surface and be less susceptible to neutralization by human antisera. Using chimeric H proteins, with and without mutations that ablate MV receptor binding, we show that retargeted MVs escape mAbs that target the H receptor-binding surface by virtue of mutations that ablate infection via SLAM and CD46. However, C-terminally displayed domains do not mediate virus entry in the presence of human antibodies that bind to the underlying H domain. In conclusion, utility of retargeted oncolytic measles viruses does not extend to evasion of human serum neutralization. PMID:24725950

The reactions of neutral iron clusters with D2O: Deconvolution of equilibrium constants from multiphoton processes

International Nuclear Information System (INIS)

Weiller, B.H.; Bechthold, P.S.; Parks, E.K.; Pobo, L.G.; Riley, S.J.

1989-01-01

The chemical reactions of neutral iron clusters with D 2 O are studied in a continuous flow tube reactor by molecular beam sampling and time-of-flight mass spectrometry with laser photoionization. Product distributions are invariant to a four-fold change in reaction time demonstrating that equilibrium is attained between free and adsorbed D 2 O. The observed negative temperature dependence is consistent with an exothermic, molecular addition reaction at equilibrium. Under our experimental conditions, there is significant photodesorption of D 2 O (Fe/sub n/(D 2 O)/sub m/ + hν → Fe/sub n/ + m D 2 O) along with ionization due to absorption of multiple photons from the ionizing laser. Using a simple model based on a rate equation analysis, we are able to quantitatively deconvolute this desorption process from the equilibrium constants. 8 refs., 1 fig

On the possible eigenoscillations of neutral sheets

International Nuclear Information System (INIS)

Almeida, W.A.; Costa, J.M. da; Aruquipa, E.G.; Sudano, J.P.

1974-12-01

A neutral sheet model with hyperbolic tangent equilibrium magnetic field and hyperbolic square secant density profiles is considered. It is shown that the equation for small oscillations takes the form of an eigenvalue oscillation problem. Computed eigenfrequencies of the geomagnetic neutral sheet were found to be in the range of the resonant frequencies of the geomagnetic plasma sheet computed by other authors

Assaying Cellular Viability Using the Neutral Red Uptake Assay.

Science.gov (United States)

Ates, Gamze; Vanhaecke, Tamara; Rogiers, Vera; Rodrigues, Robim M

2017-01-01

The neutral red uptake assay is a cell viability assay that allows in vitro quantification of xenobiotic-induced cytotoxicity. The assay relies on the ability of living cells to incorporate and bind neutral red, a weak cationic dye, in lysosomes. As such, cytotoxicity is expressed as a concentration-dependent reduction of the uptake of neutral red after exposure to the xenobiotic under investigation. The neutral red uptake assay is mainly used for hazard assessment in in vitro toxicology applications. This method has also been introduced in regulatory recommendations as part of 3T3-NRU-phototoxicity-assay, which was regulatory accepted in all EU member states in 2000 and in the OECD member states in 2004 as a test guideline (TG 432). The present protocol describes the neutral red uptake assay using the human hepatoma cell line HepG2, which is often employed as an alternative in vitro model for human hepatocytes. As an example, the cytotoxicity of acetaminophen and acetyl salicylic acid is assessed.

Impaired acid neutralization in the duodenum in pancreatic insufficiency.

Science.gov (United States)

Dutta, S K; Russell, R M; Iber, F L

1979-10-01

The influence of severe exocrine pancreatic disease on the acid-neutralizing capacity of the duodenum was studied in five patients with pancreatic insufficiency (PI) and six control subjects using duodenal perfusion-marker technique. Hydrochloric acid (0.1 N containing 1% PEG) was infused at constant rates (1.2, 4.5 and 7.0 ml/min) into the duodenum just distal to the duodenal bulb. Samples were aspirated from the tip of the duodenal perfusion tube located at the ligament of Treitz. All samples were analyzed for volume, pH, titrable acidity, PEG and [14C]PEG (gastric marker) determination. Patients with PI demonstrated significantly diminished ability to neutralize various acid loads as compared to controls who virtually completely neutralized acid loads in the range of maximal gastric acid secretion. Exogenous secretin did not significantly improve percent acid neutralized in PI. These data clearly indicate that patients with PI have significantly impaired ability to neutralize even small loads of acid in the duodenum.

Neutral Community Dynamics and the Evolution of Species Interactions.

Science.gov (United States)

Coelho, Marco Túlio P; Rangel, Thiago F

2018-04-01

A contemporary goal in ecology is to determine the ecological and evolutionary processes that generate recurring structural patterns in mutualistic networks. One of the great challenges is testing the capacity of neutral processes to replicate observed patterns in ecological networks, since the original formulation of the neutral theory lacks trophic interactions. Here, we develop a stochastic-simulation neutral model adding trophic interactions to the neutral theory of biodiversity. Without invoking ecological differences among individuals of different species, and assuming that ecological interactions emerge randomly, we demonstrate that a spatially explicit multitrophic neutral model is able to capture the recurrent structural patterns of mutualistic networks (i.e., degree distribution, connectance, nestedness, and phylogenetic signal of species interactions). Nonrandom species distribution, caused by probabilistic events of migration and speciation, create nonrandom network patterns. These findings have broad implications for the interpretation of niche-based processes as drivers of ecological networks, as well as for the integration of network structures with demographic stochasticity.

Neutral Atom Diffusion in a Partially Ionized Prominence Plasma

Science.gov (United States)

Gilbert, Holly

2010-01-01

The support of solar prominences is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force. Because the prominence plasma is only partially ionized. it is necessary to consider in addition the support of the neutral component of the prominence plasma. This support is accomplished through a frictional interaction between the neutral and ionized components of the plasma, and its efficacy depends strongly on the degree of ionization of the plasma. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a sufficiently weakly ionized plasma, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma, and consider the observational evidence for cross-field diffusion of neutral prominence material,

Physiochemical Characteristics and Molecular Structures for Digestible Carbohydrates of Silages.

Science.gov (United States)

Refat, Basim; Prates, Luciana L; Khan, Nazir A; Lei, Yaogeng; Christensen, David A; McKinnon, John J; Yu, Peiqiang

2017-10-18

The main objectives of this study were (1) to assess the magnitude of differences among new barley silage varieties (BS) selected for varying rates of in vitro neutral detergent fiber (NDF) digestibility (ivNDFD; Cowboy BS with higher ivNDFD, Copeland BS with intermediate ivNDFD, and Xena BS with lower ivNDFD) with regard to their carbohydrate (CHO) molecular makeup, CHO chemical fractions, and rumen degradability in dairy cows in comparison with a new corn silage hybrid (Pioneer 7213R) and (2) to quantify the strength and pattern of association between the molecular structures and digestibility of carbohydrates. The carbohydrate-related molecular structure spectral data was measured using advanced vibrational molecular spectroscopy (FT/IR). In comparison to BS, corn silage showed a significantly (P carbohydrates were significantly (P carbohydrate content of the silages. In conclusion, the univariate approach with only one-factor consideration (ivNDFD) might not be a satisfactory method for evaluating and ranking BS quality. FT/IR molecular spectroscopy can be used to evaluate silage quality rapidly, particularly the digestible fiber content.

Reactive formulations for a neutralization of toxic industrial chemicals

Science.gov (United States)

Tucker, Mark D [Albuqueruqe, NM; Betty, Rita G [Rio Rancho, NM

2006-10-24

Decontamination formulations for neutralization of toxic industrial chemicals, and methods of making and using same. The formulations are effective for neutralizing malathion, hydrogen cyanide, sodium cyanide, butyl isocyanate, carbon disulfide, phosgene gas, capsaicin in commercial pepper spray, chlorine gas, anhydrous ammonia gas; and may be effective at neutralizing hydrogen sulfide, sulfur dioxide, formaldehyde, ethylene oxide, methyl bromide, boron trichloride, fluorine, tetraethyl pyrophosphate, phosphorous trichloride, arsine, and tungsten hexafluoride.

Neutral particle dynamics in the Alcator C-Mod tokamak

Energy Technology Data Exchange (ETDEWEB)

Niemczewski, Artur P. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

1995-08-01

This thesis presents an experimental study of neutral particle dynamics in the Alcator C-Mod tokamak. The primary diagnostic used is a set of six neutral pressure gauges, including special-purpose gauges built for in situ tokamak operation. While a low main chamber neutral pressure coincides with high plasma confinement regimes, high divertor pressure is required for heat and particle flux dispersion in future devices such as ITER. Thus we examine conditions that optimize divertor compression, defined here as a divertor-to-midplane pressure ratio. We find both pressures depend primarily on the edge plasma regimes defined by the scrape-off-layer heat transport. While the maximum divertor pressure is achieved at high core plasma densities corresponding to the detached divertor state, the maximum compression is achieved in the high-recycling regime. Variations in the divertor geometry have a weaker effect on the neutral pressures. For otherwise similar plasmas the divertor pressure and compression are maximum when the strike point is at the bottom of the vertical target plate. We introduce a simple flux balance model, which allows us to explain the divertor neutral pressure across a wide range of plasma densities. In particular, high pressure sustained in the detached divertor (despite a considerable drop in the recycling source) can be explained by scattering of neutrals off the cold plasma plugging the divertor throat. Because neutrals are confined in the divertor through scattering and ionization processes (provided the mean-free-paths are much shorter than a typical escape distance) tight mechanical baffling is unnecessary. The analysis suggests that two simple structural modifications may increase the divertor compression in Alcator C-Mod by a factor of about 5. Widening the divertor throat would increase the divertor recycling source, while closing leaks in the divertor structure would eliminate a significant neutral loss mechanism.

Neutral particle dynamics in the Alcator C-Mod tokamak

International Nuclear Information System (INIS)

Niemczewski, A.P.

1995-08-01

This thesis presents an experimental study of neutral particle dynamics in the Alcator C-Mod tokamak. The primary diagnostic used is a set of six neutral pressure gauges, including special-purpose gauges built for in situ tokamak operation. While a low main chamber neutral pressure coincides with high plasma confinement regimes, high divertor pressure is required for heat and particle flux dispersion in future devices such as ITER. Thus we examine conditions that optimize divertor compression, defined here as a divertor-to-midplane pressure ratio. We find both pressures depend primarily on the edge plasma regimes defined by the scrape-off-layer heat transport. While the maximum divertor pressure is achieved at high core plasma densities corresponding to the detached divertor state, the maximum compression is achieved in the high-recycling regime. Variations in the divertor geometry have a weaker effect on the neutral pressures. For otherwise similar plasmas the divertor pressure and compression are maximum when the strike point is at the bottom of the vertical target plate. We introduce a simple flux balance model, which allows us to explain the divertor neutral pressure across a wide range of plasma densities. In particular, high pressure sustained in the detached divertor (despite a considerable drop in the recycling source) can be explained by scattering of neutrals off the cold plasma plugging the divertor throat. Because neutrals are confined in the divertor through scattering and ionization processes (provided the mean-free-paths are much shorter than a typical escape distance) tight mechanical baffling is unnecessary. The analysis suggests that two simple structural modifications may increase the divertor compression in Alcator C-Mod by a factor of about 5. Widening the divertor throat would increase the divertor recycling source, while closing leaks in the divertor structure would eliminate a significant neutral loss mechanism. 146 refs., 82 figs., 14 tabs

The zero-sum assumption in neutral biodiversity theory

NARCIS (Netherlands)

Etienne, R.S.; Alonso, D.; McKane, A.J.

2007-01-01

The neutral theory of biodiversity as put forward by Hubbell in his 2001 monograph has received much criticism for its unrealistic simplifying assumptions. These are the assumptions of functional equivalence among different species (neutrality), the assumption of point mutation speciation, and the

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1-xZnxFe2O4/NBR Composites over 2-12.4 GHz: A Strategic Material System for Stealth Applications

Science.gov (United States)

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-03-01

The gel to carbonate precipitate route has been used for the synthesis of Ni1-xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications.

Intra and Interspecific Variations of Gene Expression Levels in Yeast Are Largely Neutral: (Nei Lecture, SMBE 2016, Gold Coast).

Science.gov (United States)

Yang, Jian-Rong; Maclean, Calum J; Park, Chungoo; Zhao, Huabin; Zhang, Jianzhi

2017-09-01

It is commonly, although not universally, accepted that most intra and interspecific genome sequence variations are more or less neutral, whereas a large fraction of organism-level phenotypic variations are adaptive. Gene expression levels are molecular phenotypes that bridge the gap between genotypes and corresponding organism-level phenotypes. Yet, it is unknown whether natural variations in gene expression levels are mostly neutral or adaptive. Here we address this fundamental question by genome-wide profiling and comparison of gene expression levels in nine yeast strains belonging to three closely related Saccharomyces species and originating from five different ecological environments. We find that the transcriptome-based clustering of the nine strains approximates the genome sequence-based phylogeny irrespective of their ecological environments. Remarkably, only ∼0.5% of genes exhibit similar expression levels among strains from a common ecological environment, no greater than that among strains with comparable phylogenetic relationships but different environments. These and other observations strongly suggest that most intra and interspecific variations in yeast gene expression levels result from the accumulation of random mutations rather than environmental adaptations. This finding has profound implications for understanding the driving force of gene expression evolution, genetic basis of phenotypic adaptation, and general role of stochasticity in evolution. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

MP-4 Contributes to Snake Venom Neutralization by Mucuna pruriens Seeds through an Indirect Antibody-mediated Mechanism.

Science.gov (United States)

Kumar, Ashish; Gupta, Chitra; Nair, Deepak T; Salunke, Dinakar M

2016-05-20

Mortality due to snakebite is a serious public health problem, and available therapeutics are known to induce debilitating side effects. Traditional medicine suggests that seeds of Mucuna pruriens can provide protection against the effects of snakebite. Our aim is to identify the protein(s) that may be important for snake venom neutralization and elucidate its mechanism of action. To this end, we have identified and purified a protein from M. pruriens, which we have named MP-4. The full-length polypeptide sequence of MP-4 was obtained through N-terminal sequencing of peptide fragments. Sequence analysis suggested that the protein may belong to the Kunitz-type protease inhibitor family and therefore may potentially neutralize the proteases present in snake venom. Using various structural and biochemical tools coupled with in vivo assays, we are able to show that MP-4 does not afford direct protection against snake venom because it is actually a poor inhibitor of serine proteases. Further experiments showed that antibodies generated against MP-4 cross-react with the whole venom and provide protection to mice against Echis carinatus snake venom. This study shows that the MP-4 contributes significantly to the snake venom neutralization activity of M. pruriens seeds through an indirect antibody-mediated mechanism. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Controlled Folding, Motional, and Constitutional Dynamic Processes of Polyheterocyclic Molecular Strands.

Science.gov (United States)

Barboiu, Mihail; Stadler, Adrian-Mihail; Lehn, Jean-Marie

2016-03-18

General design principles have been developed for the control of the structural features of polyheterocyclic strands and their effector-modulated shape changes. Induced defined molecular motions permit designed enforcement of helical as well as linear molecular shapes. The ability of such molecular strands to bind metal cations allows the generation of coiling/uncoiling processes between helically folded and extended linear states. Large molecular motions are produced on coordination of metal ions, which may be made reversible by competition with an ancillary complexing agent and fueled by sequential acid/base neutralization energy. The introduction of hydrazone units into the strands confers upon them constitutional dynamics, whereby interconversion between different strand compositions is achieved through component exchange. These features have relevance for nanomechanical devices. We present a morphological and functional analysis of such systems developed in our laboratories. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

WHEELS OF FIRE. IV. STAR FORMATION AND THE NEUTRAL INTERSTELLAR MEDIUM IN THE RING GALAXY AM0644-741

International Nuclear Information System (INIS)

Higdon, James L.; Higdon, Sarah J. U.; Rand, Richard J.

2011-01-01

We combine data from the Australia Telescope National Facility and Swedish ESO Submillimeter Telescope to investigate the neutral interstellar medium (ISM) in AM0644-741, a large and robustly star-forming ring galaxy. The galaxy's ISM is concentrated in the 42 kpc diameter starburst ring, but appears dominated by atomic gas, with a global molecular fraction (f mol ) of only 0.062 ± 0.005. Apart from the starburst peak, the gas ring appears stable against the growth of gravitational instabilities (Q gas = 3-11). Including the stellar component lowers Q overall, but not enough to make Q 2 content. AM0644-741's star formation law is highly peculiar: H I obeys a Schmidt law while H 2 is uncorrelated with star formation rate density. Photodissociation models yield low volume densities in the ring, especially in the starburst quadrant (n ∼ 2 cm -3 ), implying a warm neutral medium dominated ISM. At the same time, the ring's pressure and ambient far-ultraviolet radiation field lead to the expectation of a predominantly molecular ISM. We argue that the ring's high SFE, low f mol and n, and peculiar star formation law follow from the ISM's ∼> 100 Myr confinement time in the starburst ring, which amplifies the destructive effects of embedded massive stars and supernovae. As a result, the ring's molecular ISM becomes dominated by small clouds, causing M H 2 to be significantly underestimated by 12 CO line fluxes: in effect, X CO >> X Gal despite the ring's ≥solar metallicity. The observed H I is primarily a low-density photodissociation product, i.e., a tracer rather than a precursor of massive star formation. Such an 'over-cooked' ISM may be a general characteristic of evolved starburst ring galaxies.

Toward Understanding the Cold, Hot, and Neutral Nature of Chinese Medicines Using in Silico Mode-of-Action Analysis.

Science.gov (United States)

Fu, Xianjun; Mervin, Lewis H; Li, Xuebo; Yu, Huayun; Li, Jiaoyang; Mohamad Zobir, Siti Zuraidah; Zoufir, Azedine; Zhou, Yang; Song, Yongmei; Wang, Zhenguo; Bender, Andreas

2017-03-27

One important, however, poorly understood, concept of Traditional Chinese Medicine (TCM) is that of hot, cold, and neutral nature of its bioactive principles. To advance the field, in this study, we analyzed compound-nature pairs from TCM on a large scale (>23 000 structures) via chemical space visualizations to understand its physicochemical domain and in silico target prediction to understand differences related to their modes-of-action (MoA) against proteins. We found that overall TCM natures spread into different subclusters with specific molecular patterns, as opposed to forming coherent global groups. Compounds associated with cold nature had a lower clogP and contain more aliphatic rings than the other groups and were found to control detoxification, heat-clearing, heart development processes, and have sedative function, associated with "Mental and behavioural disorders" diseases. While compounds associated with hot nature were on average of lower molecular weight, have more aromatic ring systems than other groups, frequently seemed to control body temperature, have cardio-protection function, improve fertility and sexual function, and represent excitatory or activating effects, associated with "endocrine, nutritional and metabolic diseases" and "diseases of the circulatory system". Compounds associated with neutral nature had a higher polar surface area and contain more cyclohexene moieties than other groups and seem to be related to memory function, suggesting that their nature may be a useful guide for their utility in neural degenerative diseases. We were hence able to elucidate the difference between different nature classes in TCM on the molecular level, and on a large data set, for the first time, thereby helping a better understanding of TCM nature theory and bridging the gap between traditional medicine and our current understanding of the human body.

Neutrino properties and neutral currents with their participation

International Nuclear Information System (INIS)

Tsukerman, I.S.

1979-01-01

Data on the neutrino properties and neutral current with their participation, published in 1977-78 are presented in the lecture. Experimental and cosmological limitations on mass, life time and neutrino oscillations are discussed. Heavy lepton properties and their relation to neutrino are considered. Neutral current data in neutrino-electron, neutrino-proton interactions and in anti νsub(μ)N interactions on nuclei are analyzed. Results of investigations of neutral currents in processes with π meson and strange particle production are given. The lecture material is based on the results presented at the last four international comferences on high energy physics

Policies and Initiatives for Carbon Neutrality in Nordic

DEFF Research Database (Denmark)

Wu, Qiuwei; Møller, Jakob Glarbo; Østergaard, Jacob

2013-01-01

Policies and initiatives promoting carbon neutrality in the Nordic heating and transport systems are presented. The focus within heating systems is the promotion of HPs (heat pumps) while the focus within transport systems is initiatives regarding EVs (electric vehicles). It is found...... for the future heating and transport systems with the ambition of realizing carbon neutrality...... that the conversion to HPs in the Nordic region relies on both private economic and national economic incentives. Initiatives toward carbon neutrality in the transport system are mostly concentrated on research, development and demonstration for deployment of a large number of EVs. All Nordic countries have plans...

Design and development of neutral beam module components

International Nuclear Information System (INIS)

Holl, P.M.; Bulmer, R.H.; Dilgard, L.W.; Horvath, J.A.; Molvik, A.W.; Porter, G.D.; Shearer, J.W.; Slack, D.S.; Colonias, J.S.

1979-01-01

The Mirror Fusion Test Facility (MFTF) injection system consists of twenty 20 keV start-up, and twenty-four 80 keV sustaining neutral beam source modules. The neutral beam modules are mounted in four clusters equally spaced around the waist of the vacuum vessel which contains the superconducting magnets. A module is defined here as an assembly consisting of a beam source and the interfacing components between that beam source and the vacuum chamber. Six major interfacing components are the subject of this paper. They are the magnetic shield, the neutralizer duct, the isolation valve, mounting gimbals, aiming bellows and actuators

Population growth enhances the mean fixation time of neutral mutations and the persistence of neutral variation.

Science.gov (United States)

Waxman, D

2012-06-01

A fundamental result of population genetics states that a new mutation, at an unlinked neutral locus in a randomly mating diploid population, has a mean time of fixation of ∼4N(e) generations, where N(e) is the effective population size. This result is based on an assumption of fixed population size, which does not universally hold in natural populations. Here, we analyze such neutral fixations in populations of changing size within the framework of the diffusion approximation. General expressions are derived for the mean and variance of the fixation time in changing populations. Some explicit results are given for two cases: (i) the effective population size undergoes a sudden change, representing a sudden population expansion or a sudden bottleneck; (ii) the effective population changes linearly for a limited period of time and then remains constant. Additionally, a lower bound for the mean time of fixation is obtained for an effective population size that increases with time, and this is applied to exponentially growing populations. The results obtained in this work show, among other things, that for populations that increase in size, the mean time of fixation can be enhanced, sometimes substantially so, over 4N(e,0) generations, where N(e,0) is the effective population size at the time the mutation arises. Such an enhancement is associated with (i) an increased probability of neutral polymorphism in a population and (ii) an enhanced persistence of high-frequency neutral variation, which is the variation most likely to be observed.

COMPARISON THEOREMS AND APPLICATIONS OF OSCILLATION OF NEUTRAL DIFFERENTIAL EQUATIONS

Institute of Scientific and Technical Information of China (English)

燕居让

1991-01-01

We first establish comparison theorems of the oscillation for a higher-order neutral delaydifferential equation. By these comparison theorems, the criterion of oscillation propertiesof neutral delay differential equation is reduced to that of nonneutral delay differential equa-tion, from which we give a series of oscillation theorems for neutral delay differentialequation.

Comparison of kinetic and fluid neutral models for attached and detached state

International Nuclear Information System (INIS)

Furubayashi, M.; Hoshino, K.; Toma, M.; Hatayama, A.; Coster, D.; Schneider, R.; Bonnin, X.; Kawashima, H.; Asakura, N.; Suzuki, Y.

2009-01-01

Neutral behavior has an important role in the transport simulations of the edge plasma. Most of the edge plasma transport codes treat neutral particles by a simple fluid model or a kinetic model. The fluid model allows faster calculations. However, the applicability of the fluid model is limited. In this study, simulation results of JT-60U from kinetic neutral model and fluid neutral model are compared under the attached and detached state, using the 2D edge plasma code package, SOLPS5.0. In the SOL region, no significant differences are observed in the upstream plasma profiles between kinetic and fluid neutral models. However, in the divertor region, large differences are observed in plasma and neutral profiles. Therefore, further optimization of the fluid neutral model should be performed. Otherwise kinetic neutral model should be used to analyze the divertor region.

Escape from neutralization by the respiratory syncytial virus-specific neutralizing monoclonal antibody palivizumab is driven by changes in on-rate of binding to the fusion protein

International Nuclear Information System (INIS)

Bates, John T.; Keefer, Christopher J.; Slaughter, James C.; Kulp, Daniel W.; Schief, William R.; Crowe, James E.

2014-01-01

The role of binding kinetics in determining neutralizing potency for antiviral antibodies is poorly understood. While it is believed that increased steady-state affinity correlates positively with increased virus-neutralizing activity, the relationship between association or dissociation rate and neutralization potency is unclear. We investigated the effect of naturally-occurring antibody resistance mutations in the RSV F protein on the kinetics of binding to palivizumab. Escape from palivizumab-mediated neutralization of RSV occurred with reduced association rate (K on ) for binding to RSV F protein, while alteration of dissociation rate (K off ) did not significantly affect neutralizing activity. Interestingly, linkage of reduced K on with reduced potency mirrored the effect of increased K on found in a high-affinity enhanced potency palivizumab variant (motavizumab). These data suggest that association rate is the dominant factor driving neutralization potency for antibodies to RSV F protein antigenic site A and determines the potency of antibody somatic variants or efficiency of escape of viral glycoprotein variants. - Highlights: • The relationship of affinity to neutralization for virus antibodies is uncertain. • Palivizumab binds to RSV escape mutant fusion proteins, but with reduced affinity. • Association rate (K on ) correlated well with the potency of neutralization

Escape from neutralization by the respiratory syncytial virus-specific neutralizing monoclonal antibody palivizumab is driven by changes in on-rate of binding to the fusion protein

Energy Technology Data Exchange (ETDEWEB)

Bates, John T. [The Vanderbilt Vaccine Center, Departments of Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States); Keefer, Christopher J. [The Vanderbilt Vaccine Center, Departments of Pediatrics, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States); Slaughter, James C. [The Vanderbilt Vaccine Center, Departments of Biostatistics and Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States); Kulp, Daniel W. [IAVI Neutralizing Antibody Center and Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA (United States); Schief, William R. [IAVI Neutralizing Antibody Center and Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA (United States); Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA (United States); Crowe, James E., E-mail: james.crowe@vanderbilt.edu [The Vanderbilt Vaccine Center, Departments of Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States); The Vanderbilt Vaccine Center, Departments of Pediatrics, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States)

2014-04-15

The role of binding kinetics in determining neutralizing potency for antiviral antibodies is poorly understood. While it is believed that increased steady-state affinity correlates positively with increased virus-neutralizing activity, the relationship between association or dissociation rate and neutralization potency is unclear. We investigated the effect of naturally-occurring antibody resistance mutations in the RSV F protein on the kinetics of binding to palivizumab. Escape from palivizumab-mediated neutralization of RSV occurred with reduced association rate (K{sub on}) for binding to RSV F protein, while alteration of dissociation rate (K{sub off}) did not significantly affect neutralizing activity. Interestingly, linkage of reduced K{sub on} with reduced potency mirrored the effect of increased K{sub on} found in a high-affinity enhanced potency palivizumab variant (motavizumab). These data suggest that association rate is the dominant factor driving neutralization potency for antibodies to RSV F protein antigenic site A and determines the potency of antibody somatic variants or efficiency of escape of viral glycoprotein variants. - Highlights: • The relationship of affinity to neutralization for virus antibodies is uncertain. • Palivizumab binds to RSV escape mutant fusion proteins, but with reduced affinity. • Association rate (K{sub on}) correlated well with the potency of neutralization.

TFTR neutral beam injection system conceptual design

International Nuclear Information System (INIS)

1975-01-01

Three subsystems are described in the following chapters: (1) Neutral Beam Injection Line; (2) Power Supplies; and (3) Controls. Each chapter contains two sections: (1) Functions and Design Requirements; this is a brief listing of the requirements of components of the subsystem. (2) Design Description; this section describes the design and cost estimates. The overall performance requirements of the neutral beam injection system are summarized. (MOW)

Modeling and experimental studies of the DIII-D neutral beam system

Energy Technology Data Exchange (ETDEWEB)

Crowley, B., E-mail: crowleyb@fusion.gat.com; Rauch, J.; Scoville, J.T.

2015-10-15

Highlights: • The issues surrounding proposals to increase neutral beam power are evaluated. • A tetrode version of the DIII-D ion source is modeled. • A neutralization efficiency of the DIII-D neutral beam is measured. • A power loading model of the neutral beam line is presented. - Abstract: In this paper, we present the results of beam physics experimental and modeling efforts aimed at learning from and building on the experience of the DIII-D off-axis neutral beam upgrade and other neutral beam system upgrades such as those at JET. The modeling effort includes electrostatic accelerator modeling (using a Poisson solver), gas dynamics modeling for the neutralizer and beam transport models for the beamline. Experimentally, spectroscopic and calorimetric techniques are used to evaluate the system performance. We seek to understand and ameliorate problems such as anomalous power deposition, originating from misdirected or excessively divergent beam particles, on a number of beamline components. We qualitatively and quantitatively evaluate possible project risks such as neutralization efficiency deficit and high voltage hold off associated with increasing the beam energy up to 105 keV.

A dirty window diffuse and translucent molecular gas in the interstellar medium

CERN Document Server

Magnani, Loris

2017-01-01

This book provides an introduction to the physics of interstellar gas in the Galaxy. It deals with the diffuse interstellar medium which supplies a complex environment for exploring the neutral gas content of a galaxy like the Milky Way and the techniques necessary for studying this non-stellar component. After an initial exposition of the phases of the interstellar medium and the role of gas in a spiral galaxy, the authors discuss the transition from atomic to molecular gas. They then consider basic radiative transfer and molecular spectroscopy with particular emphasis on the molecules useful for studying low-density molecular gas. Observational techniques for investigating the gas and the dust component of the diffuse interstellar medium throughout the electromagnetic spectrum are explored emphasizing results from the recent Herschel and Planck missions. A brief exposition on dust in the diffuse interstellar medium is followed by a discussion of molecular clouds in general and high-latitude molecular clouds...

Real time neutral beam power control on MAST

Energy Technology Data Exchange (ETDEWEB)

Homfray, David A., E-mail: david.homfray@ccfe.ac.uk [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon (United Kingdom); Benn, A.; Ciric, D.; Day, I.; Dunkley, V.; Keeling, D.; Khilar, S.; King, D.; King, R. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon (United Kingdom); Kurutz, U. [Department of Experimental Plasma Physics, University of Augsburg, Augsburg (Germany); Payne, D.; Simmonds, M.; Stevenson, P.; Tame, C. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon (United Kingdom)

2011-10-15

Real time power control of neutral beam provides an excellent tool for many different plasma physics studies. Power control at a better resolution than the level of a single injector is usually achieved by modulating individual power supplies. However, the short beam slowing down time on MAST is such that the plasma would be sensitive to modulating the neutral beam using this 100% on-off pulse-width modulation method. A novel alternative method of power control has been demonstrated, where the arc current, and hence beam current, has been controlled in real time allowing variations in neutral beam power. This has been demonstrated in a MAST plasma with almost no loss of transmission as a consequence of the optical properties of the high perveance MAST neutral beam system. This paper will detail the methodology, experiment and results and discuss the full implementation of this method that will allow MAST to control the beam power in real time.

Identification of neutral tumor evolution across cancer types

Science.gov (United States)

Barnes, Chris P; Graham, Trevor A; Sottoriva, Andrea

2016-01-01

Despite extraordinary efforts to profile cancer genomes, interpreting the vast amount of genomic data in the light of cancer evolution remains challenging. Here we demonstrate that neutral tumor evolution results in a power-law distribution of the mutant allele frequencies reported by next-generation sequencing of tumor bulk samples. We find that the neutral power-law fits with high precision 323 of 904 cancers from 14 types, selected from different cohorts. In malignancies identified as neutral, all clonal selection occurred prior to the onset of cancer growth and not in later-arising subclones, resulting in numerous passenger mutations that are responsible for intra-tumor heterogeneity. Reanalyzing cancer sequencing data within the neutral framework allowed the measurement, in each patient, of both the in vivo mutation rate and the order and timing of mutations. This result provides a new way to interpret existing cancer genomic data and to discriminate between functional and non-functional intra-tumor heterogeneity. PMID:26780609

C-X neutral spectra from ZT-40M

International Nuclear Information System (INIS)

Munson, C.; Carolan, P.G.; Bunting, C.A.

1988-01-01

A series of experiments have recently been completed on the ZT-40M Reversed Field Pinch at Los Alamos for which Neutral Charge Exchange (C-X) spectra have been measured using both the previously reported Time-of-Flight (TOF) system, and a 5 channel electrostatic Neutral Particle Analyzer (NPA). The experiments involved measurements of ion and electron temperatures for a variety of discharge conditions including scans of flat-top current levels, different values of the toroidal field reversal parameter (F = B phi (a)/ phi >), ramped current discharges, discharges with a movable graphite paddle limiter inserted into the edge of the plasma from above, and discharges with Deuterium pellet injection. Both the TOF and NPA systems view the plasma along chords from the outside midplane, and are separated by 60 0 toroidally. Core ion temperatures are obtained by examining the asymptotic tail of the neutral particle efflux spectrum. Detailed comparisons of the neutral particle spectra obtained with these two systems for the various operating conditions will be presented

Three-dimensional calculations of charge neutralization by neutral gas release

International Nuclear Information System (INIS)

Mandell, M.J.; Jongeward, G.A.; Katz, I.

1993-01-01

There have been numerous observations of high rocket or spacecraft potentials, both positive and negative, and both naturally and artificially induced, being neutralized during thruster firings. Two current studies, CHARGE-2B (positive polarity) and SPEAR3 (negative polarity), attempt a more systematic exploration of this phenomenon. The authors present here calculations performed in support of the SPEAR-3 program. (1) Conventional phenomenology of breakdown is applied to the three-dimensional system formed by the electrostatic potential and plume density fields. Using real cross sections, they calculate the paths along which the nozzle plume can support breakdown. This leads to a recommendation that the higher flow rate on SPEAR-3 be 2 g/s of argon, equal to the CHARGE-2B flow rate. (2) In a laboratory chamber, conditions (pressure of ∼ 2 x 10 - 5 torr) favor breakdown of the positive (electron-collecting) sheath for SPEAR-3 geometry. Three-dimensional calculations illustrate the evolution of the space charge and potential structure during the breakdown process. These calculations demonstrate the ability to apply accepted phenomenology to real systems with three dimensional electrostatic potential fields, space charge fields, and neutral density fields, including magnetic field effects and real cross-section data

Greenhouse gas neutral Germany in 2050

International Nuclear Information System (INIS)

Benndorf, Rosemarie; Bernicke, Maja; Bertram, Andreas

2014-01-01

In order to answer the question how a greenhouse gas neutral Germany would look like an interdisciplinary process was started by the Federal Environmental Agency. It was clear from the beginning of this work that a sustainable regenerative energy supply could not be sufficient. Therefore all relevant emission sources were included into the studies: traffic, industry, waste and waste water, agriculture, land usage, land usage changes and forestry. The necessary transformation paths to reach the aim of a greenhouse gas neutral Germany in 2050, economic considerations and political instruments were not part of this study.

Neutral beam injection in 2XIIB

International Nuclear Information System (INIS)

Hibbs, S.M.

1975-01-01

Integrated into the operation of the 2XIIB controlled fusion experiment is a 600-A, 20-keV neutral injection system: the highest neutral-beam current capacity of any existing fusion machine. This paper outlines the requirements of the injection system and the design features to which they led. Both mechanical and electrical aspects are discussed. Also included is a brief description of some operational aspects of the system and some of the things we have learned along the way, as well as a short history of the most significant developments

The net neutrality debate on Twitter

Directory of Open Access Journals (Sweden)

Wolf J. Schünemann

2015-12-01

Full Text Available The internet has been seen as a medium that empowers individual political actors in relation to established political elites and media gatekeepers. The present article discusses this “net empowerment hypothesis” and tests it empirically by analysing Twitter communication on the regulation of net neutrality. We extracted 503.839 tweets containing #NetNeutrality posted between January and March 2015 and analysed central developments and the network structure of the debate. The empirical results show that traditional actors from media and politics still maintain a central role.

Neutral particle transport modeling with a reflective source in the plasma edge

International Nuclear Information System (INIS)

Valenti, M.E.

1992-01-01

A reflective source term is incorporated into the Boltzmann neutral particle transport equation to account for boundary reflection. This reflective neutral model is integrated over a uniform axis and subsequently discretized. The discrete two-dimensional equations are solved iteratively with a computer code. The results of the reflective neutral model computer code are benchmarked with the neutral particle transport code ONEDANT. The benchmark process demonstrates the validity of the reflective neutral model. The reflective neutral model is coupled to the Braams plasma particle and energy transport code. The coupled system generates self-consistent plasma edge transport solutions. These solutions, which utilize the transport equation are similar to solutions which utilize simple plasma edge neutral models when high recycle divertors are modeled. In the high recycle mode, the high electron density at the divertor plate reduces the mean free path of plate neutrals. Hence, the similarity in results. It is concluded that simple neutral models are sufficient for the analysis of high recycle power reactor edge plasmas. Low recycle edge plasmas were not examined

Ion Flux Measurements in Electron Beam Produced Plasmas in Atomic and Molecular Gases

Science.gov (United States)

Walton, S. G.; Leonhardt, D.; Blackwell, D. D.; Murphy, D. P.; Fernsler, R. F.; Meger, R. A.

2001-10-01

In this presentation, mass- and time-resolved measurements of ion fluxes sampled from pulsed, electron beam-generated plasmas will be discussed. Previous works have shown that energetic electron beams are efficient at producing high-density plasmas (10^10-10^12 cm-3) with low electron temperatures (Te < 1.0 eV) over the volume of the beam. Outside the beam, the plasma density and electron temperature vary due, in part, to ion-neutral and electron-ion interactions. In molecular gases, electron-ion recombination plays a significant role while in atomic gases, ion-neutral interactions are important. These interactions also determine the temporal variations in the electron temperature and plasma density when the electron beam is pulsed. Temporally resolved ion flux and energy distributions at a grounded electrode surface located adjacent to pulsed plasmas in pure Ar, N_2, O_2, and their mixtures are discussed. Measurements are presented as a function of operating pressure, mixture ratio, and electron beam-electrode separation. The differences in the results for atomic and molecular gases will also be discussed and related to their respective gas-phase kinetics.

MAVEN Pickup Ion Constraints on Mars Neutral Escape

Science.gov (United States)

Rahmati, A.; Larson, D. E.; Cravens, T.; Lillis, R. J.; Dunn, P.; Halekas, J. S.; McFadden, J. P.; Mitchell, D. L.; Thiemann, E.; Connerney, J. E. P.; DiBraccio, G. A.; Espley, J. R.; Eparvier, F. G.

2017-12-01

Mars is currently losing its atmosphere mainly due to the escape of neutral hydrogen and oxygen. Directly measuring the rate of escaping neutrals is difficult, because the neutral density in the Mars exosphere is dominated, up to several Martian radii, by atoms that are gravitationally bound to the planet. Neutral atoms in the Martian exosphere, however, can get ionized, picked up, and accelerated by the solar wind motional electric field and energized to energies high enough for particle detectors to measure them. The MAVEN SEP instrument detects O+ pickup ions that are created at altitudes where the escaping part of the exosphere is dominant. Fluxes of these ions reflect neutral densities in the distant exosphere of Mars, allowing us to constrain neutral oxygen escape rates. The MAVEN SWIA and STATIC instruments measure pickup H+ and O+ created closer to Mars; comparisons of these data with models can be used to constrain exospheric hot O and thermal H densities and escape rates. In this work, pickup ion measurements from SEP, SWIA, and STATIC, taken during the first 3 Earth years of the MAVEN mission, are compared to the outputs of a pickup ion model to constrain the variability of neutral escape at Mars. The model is based on data from six MAVEN instruments, namely, MAG providing magnetic field used in calculating pickup ion trajectories, SWIA providing solar wind velocity as well as 3D pickup H+ and O+ spectra, SWEA providing solar wind electron spectrum used in electron impact ionization rate calculations, SEP providing pickup O+ spectra, STATIC providing mass resolved 3D pickup H+ and O+ spectra, and EUVM providing solar EUV spectra used in photoionization rate calculations. A variability of less than a factor of two is observed in hot oxygen escape rates, whereas thermal escape of hydrogen varies by an order of magnitude with Mars season. This hydrogen escape variability challenges our understanding of the H cycle at Mars, but is consistent with other

Emotional and neutral scenes in competition: orienting, efficiency, and identification.

Science.gov (United States)

Calvo, Manuel G; Nummenmaa, Lauri; Hyönä, Jukka

2007-12-01

To investigate preferential processing of emotional scenes competing for limited attentional resources with neutral scenes, prime pictures were presented briefly (450 ms), peripherally (5.2 degrees away from fixation), and simultaneously (one emotional and one neutral scene) versus singly. Primes were followed by a mask and a probe for recognition. Hit rate was higher for emotional than for neutral scenes in the dual- but not in the single-prime condition, and A' sensitivity decreased for neutral but not for emotional scenes in the dual-prime condition. This preferential processing involved both selective orienting and efficient encoding, as revealed, respectively, by a higher probability of first fixation on--and shorter saccade latencies to--emotional scenes and by shorter fixation time needed to accurately identify emotional scenes, in comparison with neutral scenes.

Multigroup calculations of low-energy neutral transport in tokamak plasmas

International Nuclear Information System (INIS)

Gilligan, J.G.; Gralnick, S.L.; Price, W.G. Jr.; Kammash, T.

1978-01-01

Multigroup discrete ordinates methods avoid many of the approximations that have been used in previous neutral transport analyses. Of particular interest are the neutral profiles generated as an integral part of larger plasma system simulation codes. To determine the appropriateness of utilizing a particular multigroup code, ANISN, for this purpose, results are compared with the neutral transport module of the Duechs code. For a typical TFTR plasma, predicted neutral densities differ by a maximum factor of three on axis and outfluxes at the plasma boundary by approximately 40%. This is found to be significant for a neutral transport module. Possible sources of the observed discrepancies are indicated from an analysis of the approximations used in the Duechs model. Recommendations are made concerning the future application of the multigroup method. (author)

CFD Modeling of Non-Neutral Atmospheric Boundary Layer Conditions

DEFF Research Database (Denmark)

Koblitz, Tilman

model results. A method is developed how to simulate the time-dependant non-neutral ABL flow over complex terrain: a precursor simulation is used to specify unsteady inlet boundary conditions on complex terrain domains. The advantage of the developed RANS model framework is its general applicability...... characteristics of neutral and non-neutral ABL flow. The developed ABL model significantly improves the predicted flow fields over both flat and complex terrain, when compared against neutral models and measurements....... cost than e.g. using large-eddy simulations. The developed ABL model is successfully validated using a range of different test cases with increasing complexity. Data from several large scale field campaigns, wind tunnel experiments, and previous numerical simulations is presented and compared against...

Broadly-Reactive Neutralizing and Non-neutralizing Antibodies Directed against the H7 Influenza Virus Hemagglutinin Reveal Divergent Mechanisms of Protection.

Directory of Open Access Journals (Sweden)

Gene S Tan

2016-04-01

Full Text Available In the early spring of 2013, Chinese health authorities reported several cases of H7N9 influenza virus infections in humans. Since then the virus has established itself at the human-animal interface in Eastern China and continues to cause several hundred infections annually. In order to characterize the antibody response to the H7N9 virus we generated several mouse monoclonal antibodies against the hemagglutinin of the A/Shanghai/1/13 (H7N9 virus. Of particular note are two monoclonal antibodies, 1B2 and 1H5, that show broad reactivity to divergent H7 hemagglutinins. Monoclonal antibody 1B2 binds to viruses of the Eurasian and North American H7 lineages and monoclonal antibody 1H5 reacts broadly to virus isolates of the Eurasian lineage. Interestingly, 1B2 shows broad hemagglutination inhibiting and neutralizing activity, while 1H5 fails to inhibit hemagglutination and demonstrates no neutralizing activity in vitro. However, both monoclonal antibodies were highly protective in an in vivo passive transfer challenge model in mice, even at low doses. Experiments using mutant antibodies that lack the ability for Fc/Fc-receptor and Fc/complement interactions suggest that the protection provided by mAb 1H5 is, at least in part, mediated by the Fc-fragment of the mAb. These findings highlight that a protective response to a pathogen may not only be due to neutralizing antibodies, but can also be the result of highly efficacious non-neutralizing antibodies not readily detected by classical in vitro neutralization or hemagglutination inhibition assays. This is of interest because H7 influenza virus vaccines induce only low hemagglutination inhibiting antibody titers while eliciting robust antibody titers as measured by ELISA. Our data suggest that these binding but non-neutralizing antibodies contribute to protection in vivo.

LADEE Neutral Mass Spectrometer Data

Data.gov (United States)

National Aeronautics and Space Administration — This bundle contains the data collected by the Neutral Mass Spectrometer (NMS) instrument aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE)...

Characterization of human monoclonal antibodies that neutralize multiple poliovirus serotypes.

Science.gov (United States)

Puligedda, Rama Devudu; Kouiavskaia, Diana; Al-Saleem, Fetweh H; Kattala, Chandana Devi; Nabi, Usman; Yaqoob, Hamid; Bhagavathula, V Sandeep; Sharma, Rashmi; Chumakov, Konstantin; Dessain, Scott K

2017-10-04

Following the eradication of wild poliovirus (PV), achieving and maintaining a polio-free status will require eliminating potentially pathogenic PV strains derived from the oral attenuated vaccine. For this purpose, a combination of non-cross-resistant drugs, such as small molecules and neutralizing monoclonal antibodies (mAbs), may be ideal. We previously isolated chimpanzee and human mAbs capable of neutralizing multiple PV types (cross-neutralization). Here, we describe three additional human mAbs that neutralize types 1 and 2 PV and one mAb that neutralizes all three types. Most bind conformational epitopes and have unusually long heavy chain complementarity determining 3 domains (HC CDR3). We assessed the ability of the mAbs to neutralize A12 escape mutant PV strains, and found that the neutralizing activities of the mAbs were disrupted by different amino acid substitutions. Competitive binding studies further suggested that the specific mAb:PV interactions that enable cross-neutralization differ among mAbs and serotypes. All of the cloned mAbs bind PV in the vicinity of the "canyon", a circular depression around the 5-fold axis of symmetry through which PV recognizes its cellular receptor. We were unable to generate escape mutants to two of the mAbs, suggesting that their epitopes are important for the PV life cycle. These data indicate that PV cross-neutralization involves binding to highly conserved structures within the canyon that binds to the cellular receptor. These may be facilitated by the long HC CDR3 domains, which may adopt alternative binding configurations. We propose that the human and chimpanzee mAbs described here could have potential as anti-PV therapeutics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mapping Determinants of Virus Neutralization and Viral Escape for Rational Design of a Hepatitis C Virus Vaccine

Directory of Open Access Journals (Sweden)

Mei-Le Keck

2018-05-01

Full Text Available Hepatitis C virus (HCV continues to spread worldwide with an annual increase of 1.75 million new infections. The number of HCV cases in the U.S. is now greater than the number of HIV cases and is increasing in young adults because of the opioid epidemic sweeping the country. HCV-related liver disease is the leading indication of liver transplantation. An effective vaccine is of paramount importance to control and prevent HCV infection. While this vaccine will need to induce both cellular and humoral immunity, this review is focused on the required antibody responses. For highly variable viruses, such as HCV, isolation and characterization of monoclonal antibodies mediating broad virus neutralization are an important guide for vaccine design. The viral envelope glycoproteins, E1 and E2, are the main targets of these antibodies. Epitopes on the E2 protein have been studied more extensively than epitopes on E1, due to higher antibody targeting that reflects these epitopes having higher degrees of immunogenicity. E2 epitopes are overall organized in discrete clusters of overlapping epitopes that ranged from high conservation to high variability. Other epitopes on E1 and E1E2 also are targets of neutralizing antibodies. Taken together, these regions are important for vaccine design. Another element in vaccine design is based on information on how the virus escapes from broadly neutralizing antibodies. Escape mutations can occur within the epitopes that are involved in antibody binding and in regions that are not involved in their epitopes, but nonetheless reduce the efficiency of neutralizing antibodies. An understanding on the specificities of a protective B cell response, the molecular locations of these epitopes on E1, E2, and E1E2, and the mechanisms, which enable the virus to negatively modulate neutralizing antibody responses to these regions will provide the necessary guidance for vaccine design.

Report on neutral particle detectors and QED: PEP summer study

International Nuclear Information System (INIS)

Bloom, E.D.; Bulos, F.; Buschhorn, G.

1974-08-01

The exploration of the neutral particle final states in e + e/sup /minus// annihilation using a 4π neutral particle detector is discussed. Charge particle final state physics is also considered in the context of a neutral detector. Design criteria are discussed, and a possible detector design is presented. 15 refs., 13 figs., 2 tabs

Manufacturing of neutral beam sources at Lawrence Livermore Laboratory

International Nuclear Information System (INIS)

Baird, E.D.; Duffy, T.J.; Harter, G.A.; Holland, E.D.; Kloos, W.A.; Pastrone, J.A.

1979-01-01

Over 50 neutral beam sources (NBS) of the joint Lawrence Berkeley Laboratory (LBL)/Lawrence Livermore Laboratory (LLL) design have been manufactured, since 1973, in the LLL Neutral Beam Source Facility. These sources have been used to provide start-up and sustaining neutral beams for LLL mirror fusion experiments, including 2XIIB, TMX, and Beta II. Experimental prototype 20-kV and 80-kV NBS have also been designed, built, and tested for the Mirror Fusion Test Facility (MFTF)

Status of HEP neutral net research in the USA

International Nuclear Information System (INIS)

Denby, B.; Linn, S.L.

1989-01-01

Progress on tracking with recurrent neutral networks is presented. Applications of feed-forward networks to high energy physics are discussed. The situation regarding hardware implementations of neutral networks is assessed. (orig.)

Adaptive evolutionary walks require neutral intermediates in RNA fitness landscapes.

Science.gov (United States)

Rendel, Mark D

2011-01-01

In RNA fitness landscapes with interconnected networks of neutral mutations, neutral precursor mutations can play an important role in facilitating the accessibility of epistatic adaptive mutant combinations. I use an exhaustively surveyed fitness landscape model based on short sequence RNA genotypes (and their secondary structure phenotypes) to calculate the minimum rate at which mutants initially appearing as neutral are incorporated into an adaptive evolutionary walk. I show first, that incorporating neutral mutations significantly increases the number of point mutations in a given evolutionary walk when compared to estimates from previous adaptive walk models. Second, that incorporating neutral mutants into such a walk significantly increases the final fitness encountered on that walk - indeed evolutionary walks including neutral steps often reach the global optimum in this model. Third, and perhaps most importantly, evolutionary paths of this kind are often extremely winding in their nature and have the potential to undergo multiple mutations at a given sequence position within a single walk; the potential of these winding paths to mislead phylogenetic reconstruction is briefly considered. Copyright © 2010 Elsevier Inc. All rights reserved.

Hexon and fiber of adenovirus type 14 and 55 are major targets of neutralizing antibody but only fiber-specific antibody contributes to cross-neutralizing activity.

Science.gov (United States)

Feng, Ying; Sun, Xikui; Ye, Xianmiao; Feng, Yupeng; Wang, Jinlin; Zheng, Xuehua; Liu, Xinglong; Yi, Changhua; Hao, Mingli; Wang, Qian; Li, Feng; Xu, Wei; Li, Liang; Li, Chufang; Zhou, Rong; Chen, Ling; Feng, Liqiang

2018-05-01

Re-emerging human adenoviruses type 14 (HAdV14) and 55 (HAdV55) represent two highly virulent adenoviruses. The neutralizing antibody (nAb) responses elicited by infection or immunization remain largely unknown. Herein, we generated hexon-chimeric HAdV14 viruses harboring each single or entire hexon hyper-variable-regions (HVR) from HAdV55, and determined the neutralizing epitopes of human and mouse nAbs. In human sera, hexon-targeting nAbs are type-specific and mainly recognize HVR2, 5, and 7. Fiber-targeting nAbs are only detectable in sera cross-neutralizing HAdV14 and HAdV55 and contribute substantially to cross-neutralization. Penton-binding antibodies, however, show no significant neutralizing activities. In mice immunized with HAdV14 or HAdV55, a single immunization mainly elicited hexon-specific nAbs, which recognized HAdV14 HVR1, 2, and 7 and HAdV55 HVR1 and 2, respectively. After a booster immunization, cross-neutralizing fiber-specific nAbs became detectable. These results indicated that hexon elicits type-specific nAbs whereas fiber induces cross-neutralizing nAbs to HAdV14 and HAdV55, which are of significance in vaccine development. Copyright © 2018 Elsevier Inc. All rights reserved.

Trapping neutral molecules in a traveling potential well

NARCIS (Netherlands)

Bethlem, H. L.; G. Berden,; van Roij, A. J. A.; Crompvoets, F. M. H.; Meijer, G.

2000-01-01

A series of pulsed electric fields can be arranged such that it creates a traveling potential well in which neutral dipolar molecules can be confined. This provides a method to transport, to decelerate, and to cool a sample of neutral molecules while maintaining the initial phase-space density. This

Neutral injection experiments on the ISX-B tokamak

International Nuclear Information System (INIS)

Scott, S.D.

1983-01-01

The following topics are described: (1) review of confinement scaling in ISX-B with strong neutral injection in clean plasmas, (2) discussion of observed energy confinement improvement in slightly contaminated discharges (factor less than or equal to 2), and (3) preliminary evaluation of confinement with balanced neutral beam injection

Material failures observed in the Doublet III neutral beamlines

International Nuclear Information System (INIS)

Bailey, E.W.; Colleraine, A.; Doll, D.; Grunloh, H.; Kim, J.; Langhorn, A.; Thurgood, B.

1983-01-01

The Doublet III neutral beam injectors consist of three separable spools two meters in diameter by four meters long overall when assembled. Contained within these spools are the neutralizers, ion dumps, deflecting magnet, calorimeter dumps, cryogenic panels and beam scraping collimators. To date three beamlines are in operation on Doublet III, and the beams have accumulated operating time of approximately 32 months, with the oldest having been in operation for 18 months. During this time operation of DIII with the neutral beam sources has demonstrated the following: 7.8 MW injected neutrals from three beamlines (6 sources), high β (4.5%), and non-circular plasma shape. The sources have also exibited a very reliable injected shot history. Material failures encountered during the operation of DIII N.B. injectors and the solutions to these failures are described. Failures include cracking of the neutralizer exit collimator due to heating cycles, failure of cyropanel support rods due to cooling cycles, failure of the sliding drive of the moveable calorimeter due to friction

Antihypertensive neutral lipid

Science.gov (United States)

Snyder, F.L.; Blank, M.L.

1984-10-26

The invention relates to the discovery of a class of neutral acetylated either-linked glycerolipids having the capacity to lower blood presure in warm-blooded animals. This physiological effect is structure sensitive requiring a long chain alkyl group at the sn-1 position and a short carbon chain acyl group (acetyl or propionyl) at the sn-2 position, and a hydroxyl group at the sn-3 position.

Applications of neutral beam and rf technologies

International Nuclear Information System (INIS)

Haselton, H.H.

1987-04-01

This presentation provides an update on the applications of neutral beams and radiofrequency (rf) power in the fusion program; highlights of the ion cyclotron heating (ICH) experiments now in progress, as well as the neutral beam experiments; and heating requirements of future devices and some of the available options. Some remarks on current drive are presented because this area of technology is one that is being considered for future devices

Using self-consistent Gibbs free energy surfaces to calculate size distributions of neutral and charged clusters for the sulfuric acid-water binary system

Science.gov (United States)

Smith, J. A.; Froyd, K. D.; Toon, O. B.

2012-12-01

We construct tables of reaction enthalpies and entropies for the association reactions involving sulfuric acid vapor, water vapor, and the bisulfate ion. These tables are created from experimental measurements and quantum chemical calculations for molecular clusters and a classical thermodynamic model for larger clusters. These initial tables are not thermodynamically consistent. For example, the Gibbs free energy of associating a cluster consisting of one acid molecule and two water molecules depends on the order in which the cluster was assembled: add two waters and then the acid or add an acid and a water and then the second water. We adjust the values within the tables using the method of Lagrange multipliers to minimize the adjustments and produce self-consistent Gibbs free energy surfaces for the neutral clusters and the charged clusters. With the self-consistent Gibbs free energy surfaces, we calculate size distributions of neutral and charged clusters for a variety of atmospheric conditions. Depending on the conditions, nucleation can be dominated by growth along the neutral channel or growth along the ion channel followed by ion-ion recombination.

Molecular dynamics simulation of siderite-hematite-quartz flotation with sodium oleate

Science.gov (United States)

Li, Lixia; Hao, Haiqing; Yuan, Zhitao; Liu, Jiongtian

2017-10-01

Models of sodium oleate adsorption on siderite, hematite and quartz were investigated by molecular dynamic simulation, respectively. Surface energy was calculated to confirm the cleavage plan of hematite and quartz. Both natural cleavage plane of siderite and calculated plane were used to investigate the flotation of the three minerals. Based on the molecular simulation in solution with water as medium, adsorption quantity and interaction capability of oleate ions on the three minerals indicated that siderite could be collected efficiently by sodium oleate at neutral pH. Results of flotation experiments were further demonstrated by analysis of relative concentration of carbon atoms and oxygen atoms.

Asymmetry in species regional dispersal ability and the neutral theory.

Directory of Open Access Journals (Sweden)

Jiajia Liu

Full Text Available The neutral assumption that individuals of either the same or different species share exactly the same birth, death, migration, and speciation probabilities is fundamental yet controversial to the neutral theory. Several theoretical studies have demonstrated that a slight difference in species per capita birth or death rates can have a profound consequence on species coexistence and community structure. Whether asymmetry in migration, a vital demographic parameter in the neutral model, plays an important role in community assembly still remains unknown. In this paper, we relaxed the ecological equivalence assumption of the neutral model by introducing differences into species regional dispersal ability. We investigated the effect of asymmetric dispersal on the neutral local community structure. We found that per capita asymmetric dispersal among species could reduce species richness of the local community and result in deviations of species abundance distributions from those predicted by the neutral model. But the effect was moderate compared with that of asymmetries in birth or death rates, unless very large asymmetries in dispersal were assumed. A large difference in species dispersal ability, if there is, can overwhelm the role of random drift and make local community dynamics deterministic. In this case, species with higher regional dispersal abilities tended to dominate in the local community. However, the species abundance distribution of the local community under asymmetric dispersal could be well fitted by the neutral model, but the neutral model generally underestimated the fundamental biodiversity number but overestimated the migration rate in such communities.

Neutral-beam performance analysis using a CCD camera

International Nuclear Information System (INIS)

Hill, D.N.; Allen, S.L.; Pincosy, P.A.

1986-01-01

We have developed an optical diagnostic system suitable for characterizing the performance of energetic neutral beams. An absolutely calibrated CCD video camera is used to view the neutral beam as it passes through a relatively high pressure (10 -5 Torr) region outside the neutralizer: collisional excitation of the fast deuterium atoms produces H/sub proportional to/ emission (lambda = 6561A) that is proportional to the local atomic current density, independent of the species mix of accelerated ions over the energy range 5 to 20 keV. Digital processing of the video signal provides profile and aiming information for beam optimization. 6 refs., 3 figs

Buried Volume Analysis for Propene Polymerization Catalysis Promoted by Group 4 Metals: a Tool for Molecular Mass Prediction

KAUST Repository

Falivene, Laura; Cavallo, Luigi; Talarico, Giovanni

2015-01-01

A comparison of the steric properties of homogeneous single site catalysts for propene polymerization using the percentage of buried volume (%VBur) as molecular descriptor is reported. The %VBur calculated on the neutral precursors of the active species seems to be a reliable tool to explain several experimental data related to the propene insertion and to the monomer chain transfer. Interestingly, a linear correlation between the buried volume calculated for a large set of neutral precursors and the energetic difference between propagation and termination steps calculated by DFT methods is found for Group 4 metal catalysts. The “master curves” derived for Ti, Zr and Hf confirm not only that the %VBur is an appropriate molecular descriptor for the systems considered but also that it could be used as tool for a large computational screening of new ligands.

Buried Volume Analysis for Propene Polymerization Catalysis Promoted by Group 4 Metals: a Tool for Molecular Mass Prediction

KAUST Repository

Falivene, Laura

2015-10-02

A comparison of the steric properties of homogeneous single site catalysts for propene polymerization using the percentage of buried volume (%VBur) as molecular descriptor is reported. The %VBur calculated on the neutral precursors of the active species seems to be a reliable tool to explain several experimental data related to the propene insertion and to the monomer chain transfer. Interestingly, a linear correlation between the buried volume calculated for a large set of neutral precursors and the energetic difference between propagation and termination steps calculated by DFT methods is found for Group 4 metal catalysts. The “master curves” derived for Ti, Zr and Hf confirm not only that the %VBur is an appropriate molecular descriptor for the systems considered but also that it could be used as tool for a large computational screening of new ligands.

Effects of stream topology on ecological community results from neutral models

Science.gov (United States)

While neutral theory and models have stimulated considerable literature, less well investigated is the effect of topology on neutral metacommunity model simulations. We implemented a neutral metacommunity model using two different stream network topologies, a widely branched netw...

Five second helium neutral beam injection using argon-frost cryopumping techniques

International Nuclear Information System (INIS)

Phillips, J.C.; Kellman, D.H.; Hong, R.; Kim, J.; Laughon, G.M.

1995-01-01

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. The DIII-D neutral beam system has routinely provided up to 20 MW of deuterium neutral beam heating in support of experiments on the DIII-D tokamak. Operation of neutral beams with helium has historically presented a problem in that pulse lengths have been limited to 500 ms due to reliance solely on volume pumping of the helium gas. Helium is not condensed on the cryopanels. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

Effect of Thermospheric Neutral Density upon Inner Trapped-belt Proton Flux

Science.gov (United States)

Wilson, Thomas L.; Lodhi, M. A. K.; Diaz, Abel B.

2007-01-01

We wish to point out that a secular change in the Earth's atmospheric neutral density alters charged-particle lifetime in the inner trapped radiation belts, in addition to the changes recently reported as produced by greenhouse gases. Heretofore, changes in neutral density have been of interest primarily because of their effect on the orbital drag of satellites. We extend this to include the orbital lifetime of charged particles in the lower radiation belts. It is known that the charged-belt population is coupled to the neutral density of the atmosphere through changes induced by solar activity, an effect produced by multiple scattering off neutral and ionized atoms along with ionization loss in the thermosphere where charged and neutral populations interact. It will be shown here that trapped-belt flux J is bivariant in energy E and thermospheric neutral density , as J(E,rho). One can conclude that proton lifetimes in these belts are also directly affected by secular changes in the neutral species populating the Earth s thermosphere. This result is a consequence of an intrinsic property of charged-particle flux, that flux is not merely a function of E but is dependent upon density rho when a background of neutrals is present.

Characterizing Peptide Neutral Losses Induced by Negative Electron-Transfer Dissociation (NETD)

Science.gov (United States)

Rumachik, Neil G.; McAlister, Graeme C.; Russell, Jason D.; Bailey, Derek J.; Wenger, Craig D.; Coon, Joshua J.

2012-01-01

We implemented negative electron-transfer dissociation (NETD) on a hybrid ion trap/Orbitrap mass spectrometer to conduct ion/ion reactions using peptide anions and radical reagent cations. In addition to sequence-informative ladders of a•- and x-type fragment ions, NETD generated intense neutral loss peaks corresponding to the entire or partial side-chain cleavage from amino acids constituting a given peptide. Thus, a critical step towards the characterization of this recently introduced fragmentation technique is a systematic study of synthetic peptides to identify common neutral losses and preferential fragmentation pathways. Examining 46 synthetic peptides with high mass accuracy and high resolution analysis permitted facile determination of the chemical composition of each neutral loss. We identified 19 unique neutral losses from 14 amino acids and three modified amino acids, and assessed the specificity and sensitivity of each neutral loss using a database of 1542 confidently identified peptides generated from NETD shotgun experiments employing high-pH separations and negative electrospray ionization. As residue-specific neutral losses indicate the presence of certain amino acids, we determined that many neutral losses have potential diagnostic utility. We envision this catalogue of neutral losses being incorporated into database search algorithms to improve peptide identification specificity and to further advance characterization of the acidic proteome. PMID:22290482

Issues in neutral currents

International Nuclear Information System (INIS)

Sehgal, L.M.

1980-01-01

The experimental results on low energy confirming the structure of the effective Lagrangian of the weak neutral current processes as predicted by the Salam-Weinberg model are reviewed. Some possible modifications of the effective Lagrangian and the feasibility of their experimental verification are also considered. (P.L.)

Weak neutral currents discovery: a giant step for particle physics

International Nuclear Information System (INIS)

Pullia, A.; Vialle, J.P.

2010-01-01

Subatomic particles interact with different kinds of forces (strong, electromagnetic, weak and gravitational). In case of the weak force, the interaction is due to the exchange of intermediate charged (W +,- ) and neutral (Z 0 ) bosons. These cases are referred as 'charged currents' and 'neutral currents', respectively. The evidence for such weak neutral currents appeared in the Gargamelle international collaboration whose aim was to study in-depth neutrino interactions (and thus weak interactions) through the use of a giant heavy liquid bubble chamber at CERN. In a collaboration meeting in March 1972, the Milan team showed the first hints of neutral currents in neutrino interactions with at least one pion outgoing. In 1974, 2 new leptonic neutral current candidate events were found in Gargamelle films and the Fermilab team confirmed the result a few months later. (A.C.)

Generation of intense polarized beams by selective neutralization of negative ions

International Nuclear Information System (INIS)

Hershcovitch, A.I.; Hinds, E.A.

1983-01-01

A novel scheme is proposed. This method is based on selective neutralization by laser negative hydrogen ions in a magnetic field. This selectivity is based on the fact that the final state of the neutralized atom depends on nuclear polarization in the magnetic field. A two-scenario approach is to be followed: one in which the resulting neutral atom is in the ground state, and in the other the neutral atom is in the n = 2 level. Limiting factors are discussed. The main advantages of this scheme are the availability of multi-ampere negative ion sources and the possibility to neutralize negative ions with very high efficiency. 15 references, 2 figures

Development of a Submillimeter Multipass Spectrometer for the Study of Molecular Ions

Science.gov (United States)

Carroll, A.; Rocher, B.; Laas, J. C.; Deprince, B. A.; Hays, B.; Weaver, S. L. Widicus; Lang, S.

2012-06-01

We have developed a multipass spectrometer for the submillimeter spectral region that is being used to study molecular ions through gas phase spectroscopy. The optical configuration is based on the design of Perry and coworkers that was implemented in the optical regime. To our knowledge, this is the first implementation of this optical configuration at long wavelengths. The setup involves two nearly concentric spherical mirrors that focus the multiple beam passes into a small area, or ``waist'', in the middle of the sample chamber. A supersonic molecular beam is coupled to the setup so that the molecular beam crosses the optical path at the waist. Initial studies have focused on neutral test molecules to probe the physical properties of the molecular beam under various arrangements of the molecular source relative to the optical path. Current studies focus on coupling a plasma discharge source to the setup to enable the study of molecular ions. Here we present the design of this instrument, compare the spectrometer capabilities to a traditional single pass spectrometer, and discuss the results of initial spectroscopic studies.

Active neutral particle diagnostics for high temperature plasma

International Nuclear Information System (INIS)

Tobita, Kenji

1993-01-01

This paper describes experimental studies related to active neutral particle diagnostics in the JT-60 tokamak. Detection efficiencies of a micro-channel plate (MCP), which has widely used in plasma diagnostics, were determined for ions and neutrals. Multi-step processes for a neutral beam is predicted to enhance the beam stopping cross section in a plasma. In order to confirm the predictions, shine-through for a hydrogen and for a helium beam was measured in the JT-60 ohmic plasmas. The measurements for a hydrogen beam resulted in the cross sectional enhancement in the beam stopping. The same experiment using a helium beam indicated that the cross sectional enhancement for helium was much smaller than that for hydrogen at almost same plasma parameters. Ion temperature diagnostic using active beam scattering was developed in data processing technique, in consideration of the device function of a neutral particle analyzer and in estimation of the effect of beam ion component. Fundamental experiments for detecting helium ions in a plasma were performed using two-electron transfer reaction between a helium atomic beam and helium ions, and the energy distribution and the density of the helium ions were determined. These experiments demonstrated promise of the two-electron transfer reaction as an alpha ash detection in a burning plasma. A parasitic neutral efflux accompanied by active beam injection was investigated. (J.P.N.)

Disruption Neutral Point Experiment on Alcator C-Mod

Science.gov (United States)

Granetz, R. S.; Nakamura, Y.

2000-10-01

Disruptions of single-null elongated plasmas generally result in loss of vertical position control, leading to a current quench occurring at the top or bottom of the machine, with all the attendant problems of halo and eddy currents flowing in divertor structures. On JT-60U, it has been found that if the plasma is operated with its magnetic axis at a particular height, called the neutral point, the initial vertical drift after a thermal quench is significantly slower than usual, and sometimes can even be arrested, thereby avoiding a current quench in the divertor region entirely. In an ongoing collaboration between MIT and JAERI, the neutral point concept is being tested in Alcator C-Mod, which has a significantly higher plasma elongation than JT-60U (1.65 vs 1.3). Calculations using TSC predict a neutral point at z~=+1 cm above the midplane (a=22 cm). The existence of a neutral point has now been experimentally confirmed, albeit at a height of z=+2.7 cm. The plasma has remained vertically stable for up to 9 ms after the disruption thermal quench, which in principle, is long enough for the PF control system to respond, if programmed appropriately. In addition, the physics of the neutral point stability on C-Mod appears to be somewhat different than that on JT-60U.

Empirical evaluation of neutral interactions in host-parasite networks.

Science.gov (United States)

Canard, E F; Mouquet, N; Mouillot, D; Stanko, M; Miklisova, D; Gravel, D

2014-04-01

While niche-based processes have been invoked extensively to explain the structure of interaction networks, recent studies propose that neutrality could also be of great importance. Under the neutral hypothesis, network structure would simply emerge from random encounters between individuals and thus would be directly linked to species abundance. We investigated the impact of species abundance distributions on qualitative and quantitative metrics of 113 host-parasite networks. We analyzed the concordance between neutral expectations and empirical observations at interaction, species, and network levels. We found that species abundance accurately predicts network metrics at all levels. Despite host-parasite systems being constrained by physiology and immunology, our results suggest that neutrality could also explain, at least partially, their structure. We hypothesize that trait matching would determine potential interactions between species, while abundance would determine their realization.

Factsheet on Energy Neutral Housing Construction; Infoblad Energieneutrale woningbouw

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-08-15

A brief overview is given of all aspects of energy-neutral building and renovating homes. Besides technique, also attention is given to process, financing, management and maintenance. This factsheet is part of a series of three factsheets on energy neutral construction of houses and buildings. The other two are: 'Factsheet on Energy Neutral Building : Definition and ambition' and 'Factsheet Energy Neutral schools and offices' [Dutch] Een kort overzicht wordt gegeven van alle aspecten van energieneutraal bouwen en renoveren van woningen. Naast techniek komen ook proces, financiering en beheer en onderhoud aan de orde. Dit Infoblad maakt deel uit van een serie van drie Infobladen over energieneutraal bouwen voor woningen en gebouwen. De andere twee zijn: 'Infoblad Energieneutraal bouwen: definitie en ambitie' en 'Infoblad Energieneutrale scholen en kantoren'.

Soluble HIV-1 envelope immunogens derived from an elite neutralizer elicit cross-reactive V1V2 antibodies and low potency neutralizing antibodies.

Directory of Open Access Journals (Sweden)

Sara Carbonetti

Full Text Available We evaluated four gp140 Envelope protein vaccine immunogens that were derived from an elite neutralizer, subject VC10042, whose plasma was able to potently neutralize a wide array of genetically distinct HIV-1 isolates. We sought to determine whether soluble Envelope proteins derived from the viruses circulating in VC10042 could be used as immunogens to elicit similar neutralizing antibody responses by vaccination. Each gp140 was tested in its trimeric and monomeric forms, and we evaluated two gp140 trimer vaccine regimens in which adjuvant was supplied at all four immunizations or at only the first two immunizations. Interestingly, all four Envelope immunogens elicited high titers of cross-reactive antibodies that recognize the variable regions V1V2 and are potentially similar to antibodies linked with a reduced risk of HIV-1 acquisition in the RV144 vaccine trial. Two of the four immunogens elicited neutralizing antibody responses that neutralized a wide array of HIV-1 isolates from across genetic clades, but those responses were of very low potency. There were no significant differences in the responses elicited by trimers or monomers, nor was there a significant difference between the two adjuvant regimens. Our study identified two promising Envelope immunogens that elicited anti-V1V2 antibodies and broad, but low potency, neutralizing antibody responses.

HLA DNA sequence variation among human populations: molecular signatures of demographic and selective events.

Directory of Open Access Journals (Sweden)

Stéphane Buhler

2011-02-01

Full Text Available Molecular differences between HLA alleles vary up to 57 nucleotides within the peptide binding coding region of human Major Histocompatibility Complex (MHC genes, but it is still unclear whether this variation results from a stochastic process or from selective constraints related to functional differences among HLA molecules. Although HLA alleles are generally treated as equidistant molecular units in population genetic studies, DNA sequence diversity among populations is also crucial to interpret the observed HLA polymorphism. In this study, we used a large dataset of 2,062 DNA sequences defined for the different HLA alleles to analyze nucleotide diversity of seven HLA genes in 23,500 individuals of about 200 populations spread worldwide. We first analyzed the HLA molecular structure and diversity of these populations in relation to geographic variation and we further investigated possible departures from selective neutrality through Tajima's tests and mismatch distributions. All results were compared to those obtained by classical approaches applied to HLA allele frequencies.Our study shows that the global patterns of HLA nucleotide diversity among populations are significantly correlated to geography, although in some specific cases the molecular information reveals unexpected genetic relationships. At all loci except HLA-DPB1, populations have accumulated a high proportion of very divergent alleles, suggesting an advantage of heterozygotes expressing molecularly distant HLA molecules (asymmetric overdominant selection model. However, both different intensities of selection and unequal levels of gene conversion may explain the heterogeneous mismatch distributions observed among the loci. Also, distinctive patterns of sequence divergence observed at the HLA-DPB1 locus suggest current neutrality but old selective pressures on this gene. We conclude that HLA DNA sequences advantageously complement HLA allele frequencies as a source of data used

Net Neutrality and Its Implications to Online Learning

Science.gov (United States)

Yamagata-Lynch, Lisa C.; Despande, Deepa R.; Do, Jaewoo; Garty, Erin; Mastrogiovanni, Jason M.; Teagu, Stephanie J.

2017-01-01

In this article, we studied net neutrality as a complex sociocultural phenomenon that can affect the works of distance education scholars and online learners. We decided to take part in this research because many distance education scholars and learners take net neutrality for granted. We engaged in a qualitative investigation of US public…

The nature and role of the gold-krypton interactions in small neutral gold clusters.

Science.gov (United States)

Mancera, Luis A; Benoit, David M

2015-03-26

We investigate the nature and role of krypton embedding in small neutral gold clusters. For some of these clusters, we observe a particular site-dependent character of the Kr binding that does not completely follow the criterion of binding at low-coordinated sites, widely accepted for interaction of a noble gas with closed-shell metal systems such as metal surfaces. We aim at understanding the effect of low dimensionality and open-shell electronic structure of the odd-numbered clusters on the noble gas-metal cluster interaction. First, we investigate the role of attractive and repulsive forces, and the frontier molecular orbitals. Second, we investigate the Au-Kr interaction in terms of reactivity and bonding character. We use a reactivity index derived from Fukui formalism, and criteria provided by the electron localization function (ELF), in order to classify the type of bonding. We carry out this study on the minimum energy structures of neutral gold clusters, as obtained using pseudo potential plane-wave density functional theory (DFT). A model is proposed that includes the effect of attractive electrostatic, van der Waals and repulsive forces, together with effects originating from orbital overlap. This satisfactorily explains minimum configurations of the noble gas-gold cluster systems, the site preference of the noble gas atoms, and changes in electronic properties.

Disposal of leached residual in heap leaching by neutralization

International Nuclear Information System (INIS)

Wang Jingmin

1993-01-01

The disposal results of leached residual with lime are described. Using the ratio of residual to lime being 100 : 1 the ideal disposal results were obtained with the effluent of the neutralized residual close to neutral

Adsorption of molecular brushes with polyelectrolyte backbones onto oppositely charged surfaces: A self-consistent field theory

NARCIS (Netherlands)

Feuz, L.; Leermakers, F.A.M.; Textor, M.; Borisov, O.V.

2008-01-01

The two-gradient version of the Scheutjens¿Fleer self-consistent field (SF-SCF) theory is employed to model the interaction between a molecular bottle brush with a polyelectrolyte backbone and neutral hydrophilic side chains and an oppositely charged surface. Our system mimics graft-copolymers with

Water absorption in neutralized Nafion membranes

International Nuclear Information System (INIS)

Rodmacq, B.; Roche, E.; Pineri, M.; Escoubez, M.; Duplessix, R.; Eisenberg, A.

1979-01-01

In this paper some results are reported about the interactions between water and Nafion neutralized with different cations. The energy of water absorption have been measured in the whole range of relative humidity pressures. Moessbauer spectra permit to get information about the change of environment of the iron atoms during the hydration. Small angle neutron and X ray scattering experiments have then been performed to define a possible phase segregation. From these results a model of clustering in the Nafion membranes is proposed. The neutralized Nafion samples have been obtained by soaking the acid samples in solutions containing the different salts

Neutral Naturalness from Orbifold Higgs Models

Science.gov (United States)

Craig, Nathaniel; Knapen, Simon; Longhi, Pietro

2015-02-01

We present a general class of natural theories in which the Higgs boson is a pseudo-Goldstone boson in an orbifolded gauge theory. The symmetry protecting the Higgs boson at low energies is an accidental global symmetry of the quadratic action, rather than a full continuous symmetry. The lightest degrees of freedom protecting the weak scale carry no standard model (SM) quantum numbers and interact with visible matter principally through the Higgs portal. This opens the door to the systematic study of "neutral naturalness": natural theories with SM-neutral states that are as yet untested by the LHC.

Net Neutrality: Background and Issues

National Research Council Canada - National Science Library

Gilroy, Angele A

2006-01-01

.... The move to place restrictions on the owners of the networks that compose and provide access to the Internet, to ensure equal access and nondiscriminatory treatment, is referred to as "net neutrality...

Consumer Ethical Decision Making: Intensity, Self-Consciousness and Neutralization Techniques

Directory of Open Access Journals (Sweden)

Syed Afzal Moshadi Shah

2017-03-01

Full Text Available The purpose of the study is to examine the effect of moral intensity on self-conscious emotions and neutralization techniques in the context of ethical decision making among consumers. A sample of 388 shopping mall retail consumers was recruited through self-administered survey technique. Descriptive statistics, exploratory factor analysis, correlation was carried out in SPSS whereas the measurement model and structural relationships were estimated using AMOS. Results indicate that moral intensity positively influences consumer’s self-consciousness, neutralization techniques and behavioural intention. Self-consciousness negatively influence consumer’s defence mechanism i.e. neutralization techniques. Neither self-consciousness nor neutralization techniques is found to have an impact on consumers’ behavioural intention. Only self-consciousness is found to complementary mediate the relationship of moral intensity and neutralization. The limitations associated with field survey and crosssectional research design are inevitable. The study offers some relevant practical implications for government, marketing professionals and academia. The study is among the pioneer studies that theoretically links and empirically examines Issue Contingent Model, theory of neutralization and self-consciousness. The study develops and tested an Urdu language version of the questionnaire for retail consumers.

Testing the Neutral Theory of Biodiversity with Human Microbiome Datasets.

Science.gov (United States)

Li, Lianwei; Ma, Zhanshan Sam

2016-08-16

The human microbiome project (HMP) has made it possible to test important ecological theories for arguably the most important ecosystem to human health-the human microbiome. Existing limited number of studies have reported conflicting evidence in the case of the neutral theory; the present study aims to comprehensively test the neutral theory with extensive HMP datasets covering all five major body sites inhabited by the human microbiome. Utilizing 7437 datasets of bacterial community samples, we discovered that only 49 communities (less than 1%) satisfied the neutral theory, and concluded that human microbial communities are not neutral in general. The 49 positive cases, although only a tiny minority, do demonstrate the existence of neutral processes. We realize that the traditional doctrine of microbial biogeography "Everything is everywhere, but the environment selects" first proposed by Baas-Becking resolves the apparent contradiction. The first part of Baas-Becking doctrine states that microbes are not dispersal-limited and therefore are neutral prone, and the second part reiterates that the freely dispersed microbes must endure selection by the environment. Therefore, in most cases, it is the host environment that ultimately shapes the community assembly and tip the human microbiome to niche regime.

Novel neutralized-beam intense neutron source for fusion technology development

International Nuclear Information System (INIS)

Osher, J.E.; Perkins, L.J.

1983-01-01

We describe a neutralized-beam intense neutron source (NBINS) as a relevant application of fusion technology for the type of high-current ion sources and neutral beamlines now being developed for heating and fueling of magnetic-fusion-energy confinement systems. This near-term application would support parallel development of highly reliable steady-state higher-voltage neutral D 0 and T 0 beams and provide a relatively inexpensive source of fusion neutrons for materials testing at up to reactor-like wall conditions. Beam-target examples described incude a 50-A mixed D-T total (ions plus neutrals) space-charge-neutralized beam at 120 keV incident on a liquid Li drive-in target, or a 50-A T 0 + T + space-charge-neutralized beam incident on either a LiD or gas D 2 target with calculated 14-MeV neutron yields of 2 x 10 15 /s, 7 x 10 15 /s, or 1.6 x 10 16 /s, respectively. The severe local heat loading on the target surface is expected to limit the allowed beam focus and minimum target size to greater than or equal to 25 cm 2

Auger vs resonance neutralization in low energy He+ ion scattering

International Nuclear Information System (INIS)

Woodruff, D.P.

1983-01-01

He + ions incident on a metal surface can neutralize either by an Auger or resonant charge exchange. While the Auger process has always been thought to be dominant, recent theoretical interest in the simpler one-electron resonance process has led to suggestions that this alone can account for the neutralization seen in low energy He + ion scattering. In this paper this assertion is analysed by looking at the wider information available on charge exchange processes for He + ion scattering through comparison with Li + ion scattering, the importance of multiple scattering in both these scattering experiments and the results of ion neutralization spectroscopy. These lead to the conclusion that while resonance neutralization to produce metastable He* may well occur at a substantial rate in He + ion scattering, the dominant process leading to loss of ions from the final scattered signal is Auger neutralization as originally proposed. (author)

Component design description of the neutral beam injectors for PLT

International Nuclear Information System (INIS)

Johnson, R.L.; Baer, M.B.; Dagenhart, W.K.; Haselton, H.H.; Mann, T.L.; Queen, C.C.; Stirling, W.L.; Whitfield, P.W.

1977-01-01

Plasma heating by injection of high energy neutrals is one of the experiments to be carried out on Princeton Large Torus (PLT). A four unit neutral beam injection system has been designed, built and tested which should inject a total of 3 MW of neutrals into PLT with a 200 millisecond pulse length. A typical system unit is described where the major components are identified. The following discussion describes each of these items along with some details of the design and fabrication problems encountered. Some early design considerations addressed the problems of separation and dumping of residual ions from the neutral beam, calorimetry of the neutrals with incident fuxes of 25 KW/cm 2 , and pumping speeds of several hundred thousand liters per second for hydrogen gas. Solutions were found for these problems while also resolving the complex dilemma of interfacing four large systems to a tokamak

The edge of neutral evolution in social dilemmas

Energy Technology Data Exchange (ETDEWEB)

Cremer, Jonas; Frey, Erwin [Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, D-80333 Muenchen (Germany); Reichenbach, Tobias [Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, Rockefeller University, 1230 York Avenue, New York, NY 10065 (United States)], E-mail: jonas.cremer@physik.uni-muenchen.de

2009-09-15

The functioning of animal as well as human societies fundamentally relies on cooperation. Yet, defection is often favorable for the selfish individual, and social dilemmas arise. Selection by individuals' fitness, usually the basic driving force of evolution, quickly eliminates cooperators. However, evolution is also governed by fluctuations that can be of greater importance than fitness differences, and can render evolution effectively neutral. Here, we investigate the effects of selection versus fluctuations in social dilemmas. By studying the mean extinction times of cooperators and defectors, a variable sensitive to fluctuations, we are able to identify and quantify an emerging 'edge of neutral evolution' that delineates regimes of neutral and Darwinian evolution. Our results reveal that cooperation is significantly maintained in the neutral regimes. In contrast, the classical predictions of evolutionary game theory, where defectors beat cooperators, are recovered in the Darwinian regimes. Our studies demonstrate that fluctuations can provide a surprisingly simple way to partly resolve social dilemmas. Our methods are generally applicable to estimate the role of random drift in evolutionary dynamics.

The edge of neutral evolution in social dilemmas

International Nuclear Information System (INIS)

Cremer, Jonas; Frey, Erwin; Reichenbach, Tobias

2009-01-01

The functioning of animal as well as human societies fundamentally relies on cooperation. Yet, defection is often favorable for the selfish individual, and social dilemmas arise. Selection by individuals' fitness, usually the basic driving force of evolution, quickly eliminates cooperators. However, evolution is also governed by fluctuations that can be of greater importance than fitness differences, and can render evolution effectively neutral. Here, we investigate the effects of selection versus fluctuations in social dilemmas. By studying the mean extinction times of cooperators and defectors, a variable sensitive to fluctuations, we are able to identify and quantify an emerging 'edge of neutral evolution' that delineates regimes of neutral and Darwinian evolution. Our results reveal that cooperation is significantly maintained in the neutral regimes. In contrast, the classical predictions of evolutionary game theory, where defectors beat cooperators, are recovered in the Darwinian regimes. Our studies demonstrate that fluctuations can provide a surprisingly simple way to partly resolve social dilemmas. Our methods are generally applicable to estimate the role of random drift in evolutionary dynamics.

Neutral pumping rates for a next step tokamak ignition device

International Nuclear Information System (INIS)

Galambos, J.D.; Peng, Y.K.M.; Heifetz, D.

1985-01-01

Neutral pumping rates are calculated for pump-limiter and divertor options of a next step tokamak ignition device using a method that accounts for the coupled effects of neutral transport and plasma transport. For both pump limiters and divertors the plasma flow into the channel surrounding the neutralizer plate is greatly reduced by the neutral recycling. The fraction of this flow that is pumped can be large (>50%) but in general is dependent on the particular geometry and plasma conditions. It is estimated that pumping speeds greater than or approximately 10 5 L/s are adequate for the exhaust requirements in the pump-limiter and the divertor cases

Understanding of Neutral Gas Transport in the Alcator C-Mod Tokamak Divertor

International Nuclear Information System (INIS)

Stotler, D.P.; Pitcher, C.S.; Boswell, C.J.; LaBombard, B.; Terry, J.L.; Elder, J.D.; Lisgo, S.

2002-01-01

A series of experiments on the effect of divertor baffling on the Alcator C-Mod tokamak provides stringent tests on models of neutral gas transport in and around the divertor region. One attractive feature of these experiments is that a trial description of the background plasma can be constructed from experimental measurements using a simple model, allowing the neutral gas transport to be studied with a stand-alone code. The neutral-ion and neutral-neutral elastic scattering processes recently added to the DEGAS 2 Monte Carlo neutral transport code permit the neutral gas flow rates between the divertor and main chamber to be simulated more realistically than before. Nonetheless, the simulated neutral pressures are too low and the deuterium Balmer-alpha emission profiles differ qualitatively from those measured, indicating an incomplete understanding of the physical processes involved in the experiment. Some potential explanations are examined and opportunities for future exploration a re highlighted. Improvements to atomic and surface physics data and models will play a role in the latter

Performance of the PDX neutral beam wall armor

International Nuclear Information System (INIS)

Kugel, H.W.; Eubank, H.P.; Kozub, T.A.; Williams, M.D.

1985-02-01

The PDX wall armor was designed to function as an inner wall thermal armor, a neutral beam diagnostic, and a large area inner toroidal plasma limiter. In this paper we discuss its thermal performance as wall armor during two years of PDX neutral beam heating experiments. During this period it provided sufficient inner wall protection to permit perpendicular heating injections into normal and disruptive plasmas as well as injections in the absence of plasma involving special experiments, calibrations, and tests important for the optimization and development of the PDX neutral beam injection system. Many of the design constraints and performance issues encountered in this work are relevant to the design of larger fusion devices

Thermospheric neutral temperatures derived from charge-exchange produced N{sub 2}{sup +} Meinel (1,0) rotational distributions

Energy Technology Data Exchange (ETDEWEB)

Mutiso, C.K.; Zettergren, M.D.; Hughes, J.M.; Sivjee, G.G. [Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States). Space Physics Research Lab.

2013-06-01

Thermalized rotational distributions of neutral and ionized N{sub 2} and O{sub 2} have long been used to determine neutral temperatures (T{sub n}) during auroral conditions. In both bright E-region (molecular emissions employed to determine T{sub n} in the E-region cannot likewise be used to obtain T{sub n} in the F-region. Nevertheless, charge-exchange reactions between high-altitude (>or similar 130 km) species provide an exception to this situation. In particular, the charge-exchange reaction O{sup +}({sup 2}D)+N{sub 2}(X) {yields}N{sub 2}{sup +} (A{sup 2}{Pi}{sub u}, {nu}' = 1) + O({sup 3}P) yields thermalized N{sub 2}{sup +} Meinel (1,0) emissions, which, albeit weak, can be used to derive neutral temperatures at altitudes of {proportional_to} 130 km and higher. In this work, we present N{sub 2}{sup +} Meinel (1,0) rotational temperatures and brightnesses obtained at Svalbard, Norway, during various auroral conditions. We calculate T{sub n} at thermospheric altitudes of 130-180 km from thermalized rotational populations of N{sub 2}{sup +} Meinel (1,0); these emissions are excited by soft electron (neutral atmosphere, although certain limiting conditions are necessary. These include precipitation of low-energy electrons, and a non-sunlit emitting layer. (orig.)

Negative Charge Neutralization in the Loops and Turns of Outer Membrane Phospholipase A Impacts Folding Hysteresis at Neutral pH.

Science.gov (United States)

McDonald, Sarah K; Fleming, Karen G

2016-11-08

Hysteresis in equilibrium protein folding titrations is an experimental barrier that must be overcome to extract meaningful thermodynamic quantities. Traditional approaches to solving this problem involve testing a spectrum of solution conditions to find ones that achieve path independence. Through this procedure, a specific pH of 3.8 was required to achieve path independence for the water-to-bilayer equilibrium folding of outer membrane protein OmpLA. We hypothesized that the neutralization of negatively charged side chains (Asp and Glu) at pH 3.8 could be the physical basis for path-independent folding at this pH. To test this idea, we engineered variants of OmpLA with Asp → Asn and Glu → Gln mutations to neutralize the negative charges within various regions of the protein and tested for reversible folding at neutral pH. Although not fully resolved, our results show that these mutations in the periplasmic turns and extracellular loops are responsible for 60% of the hysteresis in wild-type folding. Overall, our study suggests that negative charges impact the folding hysteresis in outer membrane proteins and their neutralization may aid in protein engineering applications.

A New Neutral-pH Low-GDP Peritoneal Dialysis Fluid

Science.gov (United States)

Himmele, Rainer; Jensen, Lynn; Fenn, Dominik; Ho, Chih-Hu; Sawin, Dixie-Ann; Diaz-Buxo, Jose A.

2012-01-01

♦ Background: Conventional peritoneal dialysis fluids (PDFs) consist of ready-to-use solutions with an acidic pH. Sterilization of these fluids is known to generate high levels of glucose degradation products (GDPs). Although several neutral-pH, low-GDP PD solutions have been developed, none are commercially available in the United States. We analyzed pH and GDPs in Delflex Neutral pH (Fresenius Medical Care North America, Waltham, MA, USA), the first neutral-pH PDF to be approved by the US Food and Drug Administration. ♦ Methods: We evaluated whether patients (n = 26; age range: 18 - 78 years) could properly mix the Delflex Neutral pH PDF after standardized initial training. We further analyzed the concentrations of 10 different glucose degradation products in Delflex Neutral pH PDF and compared the results with similar analyses in other commercially available biocompatible PDFs. ♦ Results: All pH measurements (n = 288) in the delivered Delflex Neutral pH solution consistently fell within the labeled range of 7.0 ± 0.4. Analysis of mixing errors showed no significant impact on the pH results. Delflex Neutral pH, Balance (Fresenius Medical Care, Bad Homburg, Germany), BicaVera (Fresenius Medical Care), and Gambrosol Trio (Gambro Lundia AB, Lund, Sweden) exhibited similar low total GDP concentrations, with maximums in the 4.25% solutions of 88 μmol/L, 74 μmol/L, 74 μmol/L, and 79 μmol/L respectively; the concentration in Physioneal (Baxter Healthcare Corporation, Deerfield, IL, USA) was considerably higher at 263.26 μmol/L. The total GDP concentration in Extraneal (Baxter Healthcare Corporation) was 63 μmol/L, being thus slightly lower than the concentrations in the 4.25% glucose solutions, but higher than the concentrations in the 1.5% and 2.5% glucose solutions. ♦ Conclusions: The new Delflex Neutral pH PDF consistently delivers neutral pH with minimal GDPs. PMID:22383632

Beam profile effects on NPB [neutral particle beam] performance

International Nuclear Information System (INIS)